ScienceWeek

SCIENCE-WEEK

A Weekly Email Digest of the News of Science

A journal devoted to the improvement of communication
between the scientific disciplines, and between scientists,
science educators, and science policy-makers.

May 19, 2000 -- Vol. 4 Number 20

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In physics, instead of saying, I have explained
such and such a phenomenon, one might say, I have
determined causes for it the absurdity of which
cannot be conclusively proved.
-- Georg Christoph Lichtenberg (1742-1799)


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Contents of This Issue:

1. History of Science:
The Puzzle of the Bohr-Heisenberg Copenhagen Meeting
----------------------------------------------------
In 1941, during the German occupation of Europe, Werner
Heisenberg traveled to Denmark to meet with Niels Bohr. What was
said at that meeting has been debated for half a century and is
now the focus of a new London and New York play, and also the
focus of new attention by physicists and the media.
(Includes related background material.)

2. Earth Science:
On the Origins of the Great Ice Ages
------------------------------------
The periodicities of the great Pleistocene ice ages have long
been considered to be related to the periodicities of certain
changes in the orbit of Earth around the Sun. Now new evidence
more accurately dating the next to the last great ice age
suggests that a rethinking of current models of the origin of ice
ages may be required. (Includes related background material.)

3. Physiology:
On Biological Clocks
--------------------
Within individual cells of the suprachiasmatic nucleus of the
mammalian brain, specialized clock genes are switched on and off
by the proteins they encode in a feedback loop that has a 24-hour
rhythm. (Includes related background material.)

4. Zoology:
Emerging Infectious Diseases of Wildlife
----------------------------------------
Many wildlife species are reservoirs of pathogens that threaten
domestic animal and human health, and emerging infectious
diseases of wildlife pose a substantial threat to the
conservation of global diversity.

5. Medical Biology:
A Revival of Electroshock Therapy
---------------------------------
Although in disfavor for several decades, electroconvulsive
therapy is currently applied to approximately 100,000 patients
each year in the US, and many more worldwide, and there is
apparently a renewed interest in the procedure as a treatment for
certain types of mental dysfunction.

6. Public Health:
Prevention of Mother-to-Child HIV Transmission
----------------------------------------------
Recent clinical trial results from international settings suggest
that short-course antiretroviral drug therapy regimens could
significantly reduce perinatal HIV transmission worldwide if
research results could be translated into practice.
(Includes related background material.)

In Focus: On Evolutionary Theory and the Social Sciences

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1. HISTORY OF SCIENCE:
THE PUZZLE OF THE BOHR-HEISENBERG COPENHAGEN MEETING
     Niels Bohr (1885-1962) and Werner Heisenberg (1901-1976),
two monumental figures in the history of physics in the 20th
century, are currently the focus of an interesting convergence of
science and the humanities as the result of the new play
_Copenhagen_ by Michael Frayn, the play originally presented in
London two years ago and now also on stage in New York.
     Bohr worked in the fields of atomic structure and nuclear
fission, and he proposed the doctrine of complementarity. As
director of the Institute of Theoretical Physics in Copenhagen
from 1920 on, Bohr was the head of what came to be called the
Copenhagen School of Quantum Mechanics, which produced the so-
called "Copenhagen orthodoxy" view of the implications of quantum
mechanics as applied in general to theoretical physics. Bohr was
awarded the Nobel Prize in Physics in 1922.
     Heisenberg developed one form of quantum theory (matrix
quantum mechanics) in the late 1920s and formulated the
uncertainty principle, which concerns matter, radiation, and
their reactions, and which places absolute limits on the
achievable accuracy of measurement of physical phenomena in the
quantum domain. Heisenberg was awarded the Nobel Prize in Physics
in 1932.
     Bohr was Danish and the son of a professor of physiology;
Heisenberg was German and the son of a professor of Byzantine
history. Early in his career, Heisenberg worked under Bohr in
Copenhagen as a research assistant, and the two men developed a
lasting friendship and an intimate working relationship --
lasting, that is, until 1941, when something happened during a
meeting of the two men in Copenhagen, and the friendship and
working relationship collapsed and was never recovered.
     The break between the two men occurred against a background
of political turmoil and war, and what happened during the break
has never been clarified and remains a puzzle. Certain background
facts are salient: a) Germany occupied Denmark in 1940 and
remained in Denmark until 1945. b) The Nazi campaign to
exterminate the Jews was in full swing all over Europe but moved
relatively slowly in Denmark; Niels Bohr, in fact, was half-
Jewish and he remained working at his institute in Copenhagen
until 1943, when he escaped to Sweden. (During the war in
Denmark, and afterward while in Sweden, Bohr helped arrange the
rescue of nearly every Danish Jew.) c) As for Heisenberg, he
remained in Germany during the entire Nazi period, and by 1940 he
was in charge of German research on the atomic bomb. d) In
September 1941, Heisenberg traveled to Copenhagen to meet with
Bohr, and that meeting apparently resulted in the termination of
their friendship.
     Physics in the 20th century benefitted especially from
personal interactions of physicists, and the causes and
consequences of a break between two physicists of the stature of
Bohr and Heisenberg are of interest. Indeed, there have been
breaks between other scientists, both in and out of physics, but
this one has been brought to the theatrical stage and it is now
under intense scrutiny.
... ... Bertram M. Schwarzchild (Physics Today, US) presents a
report of a recent symposium of physicists and others held at the
City University of New York, the symposium devoted to the
historical events surrounding the 1941 meeting between Bohr and
Heisenberg and to the theatrical interpretation of these events
by the play _Copenhagen_. Schwarzchild makes the following
points:
     1) After the war, during their next meeting in 1947, Bohr
and Heisenberg offered conflicting recollections of the meeting
in 1941. Was Heisenberg, as Bohr remembered it, trying to ferret
out information about Allied efforts to build fission weapons? Or
was Heisenberg, as Heisenberg later claimed, trying to suggest to
the physicists in Britain and America, through Bohr, that both
sides should abandon the search for the means to develop the atom
bomb?
     2) At the symposium at the City University of New York, Hans
Bethe, 93 years old and a former member of the Los Alamos team
(he left Germany in 1933), noted in an address that the Germans
failed to realize that graphite was the appropriate moderator for
a uranium reaction because Walter Bothe, the acknowledged German
authority, claimed graphite was unsuitable and, Bethe stated, the
Germans of that era did not challenge authority. In America,
Hungarian refugee Leo Szilard, talking in 1942 to the chemical
engineers who manufactured commercial graphite, discovered that
the offending impurity was boron, and that enough boron could be
removed to make graphite bricks sufficiently pure for reactors.
In his New York address, Bethe asserted that in the Germany of
that time, with its hierarchical culture, "no physicist would
have deigned to consult a chemical engineer."
     3) Schwarzchild concludes his report with a note about a
1947 letter from the physicist Max Born (1882-1970) to his son
Gustav. In this letter, Born describes a postwar conversation
with Heisenberg, Born writing of Heisenberg: "His philosophy of
life is definitely somewhat infected by Nazi ideas. He has a kind
of 'biological' creed, 'survival of the fittest', applied to
human relations, and seems to regret more that the Germans have
not turned out to be the fittest, than what we regard to be the
sad and regrettable things."
... ... In a detailed essay on the play _Copenhagen_ in the New
York Review of Books, Thomas Powers, author of a recent biography
of Heisenberg, makes the following points:
     1) At the time of the Bohr-Heisenberg meeting in 1941, the
German military, during the first weeks of the war in 1939, had
placed Heisenberg in charge of theoretical work on the
feasibility of atomic bombs, and Heisenberg remained a principal
director of uranium research "until the last shots were fired".
When the war ended, Heisenberg was in southern Germany working on
a small experimental nuclear reactor which never achieved a self-
sustaining chain reaction. It was a tiny program without
scientific or military significance.
     2) Powers points out that concerning almost every detail of
the 1941 Bohr-Heisenberg meeting there is more than one opinion,
and long books have been written attempting to sort it all out.
"Frayn [the author of the play] is not trying to establish what
really happened; it is what might, could, or should have happened
that interests him and gives the play its power as a work of
ideas."
     3) Powers states that it is possible that in 1941 Heisenberg
wanted to talk to Bohr about the one question posed twice in the
play (at the beginning and at the end): "Does one as a physicist
have the moral right to work on the practical exploitation of
atomic energy?" Powers concludes: "For the scientists who
succeeded where Heisenberg failed, and for the historians who
have recounted their efforts, answering Heisenberg's question is
no simple matter. But once the question is posed there are only
two possible responses -- to ignore the question and to dismiss
his [Heisenberg's] visit to Copenhagen as somehow safe and self-
serving, or to grant him [Heisenberg] the courtesy of an attempt
to reply." [*Note #1].
-----------
Bertram Schwarzchild: Bohr-Heisenberg Symposium Marks Broadway
Opening of _Copenhagen_.
(Physics Today May 2000)
QY: Bertram Schwarzchild [postmaster@aip.org]
-----------
Thomas Powers: The Unanswered Question
(New York Review of Books 25 May 2000)
QY: Thomas Powers [mail@nybooks.com]
-----------
Text Notes:
... ... *Note #1: The question posed by Powers (and posed in the
play), "Does one as a physicist have the moral right to work on
the practical exploitation of atomic energy?" should probably be
replaced by the question "Does one as a physicist have the moral
right to work on the _military_ exploitation of atomic energy?",
since that is what was and remains actually involved. This
revised question has been debated for more than half a century in
our time, and the debate goes on. But it is important to
distinguish this question from the related question, "Does one as
a physicist have the moral right to work on the _science_
underlying the "practical" (or military) exploitation of atomic
energy? The view of the Editor is that the most cogent answer to
this related question was provided by the physicist J. Robert
Oppenheimer (1904-1967), and the following statement by
Oppenheimer appears on the masthead of the ScienceWeek website:
"If you are a scientist you believe that it is good to find out
how the world works, that it is good to find out what the
realities are, that it is good to turn over to mankind at large
the greatest possible power to control the world... It is not
possible to be a scientist unless you believe that the knowledge
of the world, and the power which this gives, is a thing which is
of intrinsic value to humanity, and that you are using it to help
in the spread of knowledge, and are willing to take the
consequences."
-------------------
Summary & Notes by SCIENCE-WEEK http://scienceweek.com 19May00
For more information: http://scienceweek.com/swfr.htm
-------------------
Related Background:
THEORETICAL PHYSICS: ON PASCUAL JORDAN AND NAZI PHYSICS
The individual human brain is an extremely complex natural
system, and the individual human mind, the manifestation of the
dynamics of that system, is at least of an equal order of
complexity and also a domain where paradox is commonplace.
(Ernst) Pascual Jordan (1902-1980) was one of the great
theoretical physicists of this century, the principal architect
of the Born-Heisenberg-Jordan matrix quantum mechanics (see Note
#1 below), the essential inventor of *quantum field theory, and a
20th century tour de force in mathematical physics -- but he was
also an ardent Nazi storm trooper, "complete with brown uniform,
jackboots, and swastika armband..." And if that paradox is not
enough, add to it the fact that Jordan not only defended the
physics of Albert Einstein to the Nazi regime which despised
Einstein because Einstein was a Jew, but also devoted
considerable effort to developing the details of Einstein's
general theory of relativity.
... ... Engelbert L. Schucking (New York University, US),
theoretical physicist and a former student of Pascual Jordan
(beginning in 1952), presents a biographical essay on Jordan,
with Schucking making the following points:
     1) Pascual Jordan was the originator of the quantum theory
of fields, "which we now take to be the basis of all physics." He
was the first to realize that all things in the Universe --
photons, electrons, protons, atoms, and elephants -- are field
quanta. Of the triumvirate Pascual Jordan, *Max Born, and *Werner
Heisenberg that formulated matrix quantum mechanics in 1925,
Jordan was the principal architect of the theory. But in spite of
his revolutionary contributions, Jordan never achieved the
acclaim of his colleagues Heisenberg and *Wolfgang Pauli, perhaps
because Jordan was looked down upon by Pauli and Heisenberg as
more of a mathematician than a physicist.
     2) Schucking points out that Jordan also made the first
formulation of what is now called *Fermi-Dirac statistics. The
story is that in 1925 Max Born, who was then editor of the
_Zeitschrift fur Physik_ was given a paper by Jordan for
publication in the journal. Born put the paper in his briefcase
and then left for the US to give lectures at MIT. Born forgot
about the paper, and when he returned to Germany six months
later, he found the paper at the bottom of the suitcase.
According to Max Born: "It contained what came to be known as the
Fermi-Dirac statistics. In the meantime, it had been discovered
by Enrico Fermi and, independently, by Paul Dirac. But Jordan was
the first."
     3) In May 1933, Jordan joined the Nazi party. But even
before the Nazis came to power in January 1933, Jordan had been a
conservative nationalist, and under the pseudonym "Domeier" he
had published his elitist views in the right-wing journal
_Deutsches Volkstum_ (_German Heritage_). In November 1933,
Jordan joined an SA (Sturmabteilung) unit and became a storm
trooper. He volunteered for the Luftwaffe in 1939, worked mostly
as a meteorologist at airfields, and also at the notorious
Peenemunde rocket center. In 1953, thanks to the intercession of
Wolfgang Pauli, Jordan was "rehabilitated" and advanced from
visiting to full professor at the University of Hamburg.
     4) The Schucking article includes an amusing extract from a
play by *Bertolt Brecht (_Fright and Misery in the Third Reich_)
in which Brecht satirizes Nazi physics in a scene in which two
physicists execute tortuous verbalizations in an attempt to avoid
mentioning the dangerous "E-word" (Einstein). In fact, most
German physicists, when writing about relativity during the Nazi
era, shunned the dangerous E-word. Schucking notes: "A
circumspect Heisenberg managed to avoid it." Jordan, however, did
use Einstein's name when writing about relativity.
     5) Schucking notes that the contributions of Pascual Jordan
are for the most part still widely unknown. "The bulk of the
monumental 1925 Born-Jordan paper 'Zur Quantenmechanik' was
written by Jordan [*Note #1]." It has also been argued that
Jordan's habilitation lecture was crucial for Heisenberg's
discovery of the uncertainty principle. "Even Jordan's pioneering
work in quantum field theory was not immediately appreciated. His
formalism of *creation and annihilation operators, now the basic
language of physics, was still viewed with suspicion by Pauli in
1933." In a seminal paper in 1935, Jordan showed how his
formalism could treat the physics of multiparticle systems -- now
the standard treatment in condensed matter physics -- and
generate the representations that are now used in particle
physics.
     6) In 1979, *Eugene Wigner proposed Jordan for the Nobel
Prize in Physics, but the Swedish Academy awarded the prize that
year to *Sheldon Glashow, Abdus Salam, and Steven Weinberg --
according to Schucking, "three practitioners of the art that
Jordan had invented." Less than a year later, Jordan died at the
age of 78 while filling in formulae in a manuscript at his
kitchen table.
-----------
[Editor's note: The 1997 edition of _Chambers Biographical
Dictionary_ contains a short paragraph on "(Ernst) Pascual Jordan
(1902-  ) German theoretical physicist". Evidently, 17 years
after Jordan's death, the editors of the dictionary were not
aware of it. Several current popular biographical dictionaries of
scientists contain no mention of Pascual Jordan at all. David
Bohm's 1951 textbook _Quantum Theory_ does not mention Jordan at
all. The 1958 4th edition of Paul Dirac's _The Principles of
Quantum Mechanics_ does not mention Jordan at all. Jordan is also
not mentioned anywhere in Richard Feynman's _Lectures on Physics_
(1965). Additional note: Pascual Jordan (1902-1980) should not be
confused with the noted mathematician Camille Jordan (1838-1922).
Camille Jordan was the foremost specialist in algebra of his
time, publishing research in topology, analysis, and particularly
in group theory. The so-called "Jordan curve" in analysis is the
curve of Camille Jordan.]
-----------
Engelbert L. Schucking: Jordan, Pauli, politics, Brecht, and a
variable gravitational constant.
(Physics Today October 1999)
QY: Engelbert L. Schucking, Dept. of Physics, New York
University, US.
-----------
Text Notes:
... ... *quantum field theory: The mathematical fusion of quantum
mechanics with special relativity theory. It is now the overall
theory of fundamental particles and their interactions, with each
type of particle represented by appropriate operators which obey
specific algebraic commutation laws.
... ... *Max Born: (1882-1970) Nobel Prize in Physics 1954. Born
did fundamental work in quantum theory, particularly work linking
the wave function of the electron to electron distribution
probability. It was Born who apparently coined the term "quantum
mechanics". Heisenberg was one of Born's students.
... ... *Werner Heisenberg: (1901-1976) Nobel Prize in Physics
1932. Developed quantum theory (matrix quantum mechanics) and
formulated the uncertainty principle, which concerns matter,
radiation, and their reactions, and which places absolute limits
on the achievable accuracy of measurement of physical phenomena
in the quantum domain.
... ... *Wolfgang Pauli: (1900-1958) Nobel Prize in Physics 1945.
Originated the exclusion principle, which states that in a given
system no two fermions (electrons, protons, neutrons, or other
elementary particles of half-integral spin) can be characterized
by the same set of quantum numbers. He also predicted the
existence of neutrinos.
... ... *Fermi-Dirac statistics: The statistics of an assembly of
identical half-integer spin particles. Such particles satisfy the
Pauli exclusion principle, i.e., no two particles of the same
kind in the system may simultaneously occupy the same quantum
state.
... ... *Bertolt Brecht: (1898-1956) Considered by many to be
Germany's greatest dramatist, Brecht presented his plays as
instruments of sociological analysis. When Hitler came to power
in 1933, Brecht left Germany and in 1941 finally settled in
Hollywood (US). The play in question, _Fright and Misery under
the Third Reich_, is also called _Fear and Loathing under the
Third Reich_ (Furcht und Elend des dritten Reiches, 1945). In
1948, Brecht moved to East Berlin to direct a theater. Always in
conflict with bureaucratic authority, Brecht's years in East
Germany proved difficult for both himself and the East German
government.
... ... *Note #1: What is known as "Heisenberg's matrix
mechanics" (matrix quantum mechanics) is a particular formulation
of quantum mechanics in which the vector aspect of quantum theory
is emphasized, whereas the wave aspects of quantum phenomena play
a secondary role. Although wave quantum mechanics (subsequently
developed by Schroedinger, see below) and matrix quantum
mechanics appear superficially to be very different, the two
theories are in fact completely equivalent and lead to the same
physical predictions. Werner Heisenberg's first paper on the
subject appeared in 1925, and in this paper matrix theory is not
mentioned explicitly because Heisenberg did not realize yet that
his mathematical operations had a matrix theory interpretation.
The connection with matrix theory was demonstrated the same year
in the already mentioned important paper by Max Born and Pascual
Jordan (Z. fur Physik 1925 34:858). In a second paper a short
time later, Born and Jordan and Heisenberg all published together
and clarified the principles of matrix quantum mechanics (Z. fur
Physik 1926 35:557). The wave quantum mechanics of Erwin
Schroedinger was not published until 1926 (Annalen der Physik
1926 79:361), so that historically matrix mechanics was invented
and developed before Schroedinger invented wave mechanics. Given
wave mechanics, the invention of matrix mechanics might be viewed
as inevitable, since the set of all solutions of a linear
differential equation can be regarded as a vector space. The fact
that matrix mechanics was invented _without_ wave mechanics is
considered by some physicists to be an astounding theoretical
accomplishment.
... ... *creation and annihilation operators: These are quantum
mechanical operators which increase or reduce, respectively, the
occupation of a single quantum state by one. For example, an
annihilation operator applied to a state of one particle yields
the vacuum. In this context, "operators" are abstract
representations of certain specific mathematical operations, and
consideration of the various algebras of such operators has
proved to be of immense importance in theoretical physics.
... ... *Eugene Wigner: (1902-1995) He introduced the idea of
parity, or symmetry theory, into nuclear physics. He shared the
1963 Nobel Prize for Physics with Maria Goeppert-Mayer
(1906-1972) and Hans Jensen (1907-1973).
... ... *Sheldon Glashow, Abdus Salam, and Steven Weinberg:
Shared the 1979 Nobel Prize in Physics for the unified theory of
weak and electromagnetic fundamental forces, and for the
prediction of the existence of the weak neutral current. Abdus
Salam (1926-1996).
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 19Nov99
[For more information: http://scienceweek.com/swfr.htm]

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2. EARTH SCIENCE:
ON THE ORIGINS OF THE GREAT ICE AGES
Indirect data have for many years been used to reconstruct the
climate of the Earth for various periods back to the earliest
dated *sedimentary rocks, which formed approximately 3.7 billion
years ago. The more distant the time period, the more indirect is
the climatic evidence, but the record for the Pleistocene epoch
(the past 1.6 million years) is substantial enough to merit
detailed quantitative analysis and interpretation.
... ... Daniel P. Schrag (Harvard University, US) presents a
commentary on recent research concerning the periodicity of the
great Pleistocene ice ages, the author making the following
points:
     1) It was already suggested in the 1870s that ice ages were
caused by the amount of solar radiation received (irradiance) at
the poles as a result of changes in the shape of the Earth's
orbit around the Sun (such changes with a periodicity of
approximately 100,000 years), and as a result of changes in the
tilt and wobble of the orbit (with periodicities of 40,000 years
and 20,000 years, respectively). Despite the success of this
astronomical theory, some fundamental questions remain: We still
do not know how subtle changes in the pattern of solar irradiance
are amplified to produce such spectacular changes in climate --
cooling the deep ocean almost to the freezing point and extending
ice sheets thousands of kilometers towards the Equator. And we do
not understand why ice ages occur in both hemispheres
simultaneously when the changes in solar irradiance from orbital
variations have opposite effects in the north and south.
     2) Until now, analysis of the relevant geological record has
been based on oxygen isotope data from marine fossils, the data
reflecting the size of continental ice sheets. Based on this
method, the record for the past 500,000 years indicates that 10
major ice ages and warm periods occurred during this time.
Together these constitute 5 ice age cycles, which occur at
essentially the same frequency (approximately every 100,000
years) as changes in the shape of the Earth's orbit around the
Sun. For approximately the past 10,000 years, the Earth has been
experiencing a warm period (deglaciation).
     3) New evidence by G.M. Henderson and N.C. Slowey (Nature 2
Mar 2000 404:61), the evidence based on an improved method of
uranium-thorium isotope dating which allows accurate dating of
much older sediments than previous methods, provides a more
accurate date for the midpoint of the previous deglaciation
(approximately 135,000 years ago), and now the coincidence with
orbital changes is no longer so solid. The author (Schrag)
suggests that as a result of this new evidence, "we may need to
rethink our picture of what drives the ice ages."
-----------
Daniel P. Schrag: Of ice and elephants.
(Nature 2 Mar 00 404:23)
QY: Daniel P. Schrag [schrag@eps.harvard.edu]
-----------
Text Notes:
... ... *sedimentary rocks: These are rocks formed by the
hardening of accumulated particles (sediments) that were
transported by agents such as wind and water. Such rocks are the
prime source of fossils.
-------------------
Summary & Notes by SCIENCE-WEEK http://scienceweek.com 19May00
For more information: http://scienceweek.com/swfr.htm
-------------------
Related Background:
A SIMULATION MODEL FOR MODERN AND GLACIAL CLIMATES
In 1920, the meteorologist Milutin Milankovic proposed that small
changes in Earth's orbit, precession, and inclination affect the
heat balance and modify climate (the alterations called "solar
forcing"). The Milankovic hypothesis was not taken seriously
until 1976, when teams studying sediment cores from the ocean
floor constructed a history of ocean temperature that matched the
predictions of the Milankovic hypothesis, with two different
ocean cores providing similar results. Until now, simulation
models of Earth's climate history have been either ocean models
or atmosphere models, with no model accounting for the interact-
ions between the ocean and the atmosphere aside from adjustable
heat flux parameters that result in only a weak theory. In
general, complete solutions of these individual models have
involved prohibitive computation times. The term "glacial
maximum" refers to the time or position of the greatest extent of
glaciation, and the term "hydrologic cycle" refers to the
complete cycle through which water passes: from the ocean,
through the atmosphere, to the land, and back to the ocean.
... ... Ganopolski et al (4 authors at Potsdam Institute for
Climate Impact Research, DE) now report a moderately simplified
global coupled ocean-atmosphere model to simulate the equilibrium
climate of both the present and of the last glacial maximum, and
that the model successfully predicts the atmospheric and oceanic
circulations, temperature distribution, hydrologic cycle, and
sea-ice cover of both periods without using flux adjustments. The
authors suggest that changes in oceanic circulation, particularly
in the Atlantic Ocean, play an important role in glacial cooling,
and that ultimately the challenge is to produce a simulation of
glacial cycles driven only by the Milankovic cycles in solar
forcing.
QY: Stefan Rahmstorf 
(Nature 22 Jan 98) (Science-Week 6 Feb 98)
For more information: http://scienceweek.com/swfr.htm

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3. PHYSIOLOGY: ON BIOLOGICAL CLOCKS
In biology, a "circadian rhythm" is a daily cyclical process, be
it biochemical, or physiological, or behavioral. The human sleep-
wake cycle is the most familiar example. Circadian rhythms are
often described in terms of endogenous "biological clocks", with
the thrust of research to reduce some particular behavioral or
physiological circadian rhythm to biochemical events. These
clocks are usually set by environmental cues such as the light-
dark cycle, and what is characteristic of an endogenous clock is
that if one removes the environmental cue, keeps the organism in
constant light, for example, the endogenous rhythm will continue,
but will tend to drift out of phase with the outdoors
environmental light-dark cycle. Restoring the external light-dark
cue will reset the clock to its normal intrinsic rhythm.
... ... Michael W. Young (Rockefeller University, US) presents a
review of current research on circadian rhythms, the author
making the following points:
     1) In mammals, the master clock that dictates the day-night
cycle of activity known as circadian rhythm resides in a part of
the brain called the "suprachiasmatic nucleus". But cells
elsewhere also show clock activity.
     2) Within individual cells of the suprachiasmatic nucleus,
specialized clock genes are switched on and off by the proteins
they encode in a feedback loop that has a 24-hour rhythm. The
molecular rhythms of clock-gene activity do not depend on the
normal 24-hour cycle of light and darkness: these rhythms are
innate and self-sustaining, and they persist in the absence of
environmental cycles of day and night.
     3) Bright light absorbed by the retina during the day helps
to synchronize the rhythms of activity of the clock genes to the
prevailing environmental cycle. Exposure to bright light at night
resets circadian rhythms by changing the concentrations of
certain clock-gene products. The fluctuating proteins synthesized
by clock genes control additional genetic pathways that connect
the molecular clock to timed changes in physiology and behavior.
     4) The author concludes: "An exciting prospect for the
future involves the recovery of an entire system of clock-
regulated genes in organisms such as fruit flies and mice. It is
likely that previously uncharacterized gene products with
intriguing effects on behavior will be discovered within these
networks."
-----------
Michael W. Young: The tick-tock of the biological clock.
(Scientific American March 2000)
QY: Michael W. Young, Rockefeller University, 1230 York Avenue,
New York, NY 10021 US.
-------------------
Summary by SCIENCE-WEEK http://scienceweek.com 19May00
For more information: http://scienceweek.com/swfr.htm
-------------------
Related Background:
CIRCADIAN OSCILLATORS: RESETTING BY TEMPERATURE CHANGES
Many organisms exhibit daily (circadian) rhythms, cyclical
variations in various bodily functions, metabolisms, etc., the
variations having considerable endurance even in constant light
or constant darkness. Such biological clocks are most easily
studied in simple organisms. Recent research has resulted in the
identification of common elements in the molecular mechanisms of
circadian rhythms and in the ways that these mechanisms respond
to environmental cues such as light and temperature. Phase
resetting by light is understood in terms of rapid light-induced
responses of central clock biochemical components. However, a
description of how small, naturally occurring temperature cycles
can reset a clock is lacking. ... ... Liu et al (4 authors at
Dartmouth Medical School, US) now report a study of the clock
protein FRQ in *Neurospora. Levels of FRQ were measured at
various temperatures. At higher temperatures, the amount of FRQ
oscillated around higher levels. Absolute FRQ amounts thus
identified different times at different temperatures, so
temperature shifts corresponded to shifts in clock time without
immediate synthesis or turnover of components. Moderate
temperature changes could dominate light-to-dark shifts in the
influence of circadian timing. The authors suggest their results
provide insight into how physiologically and ecologically
relevant temperature steps and pulses act to reset a day-phase
circadian oscillator. They further suggest their results provide
another example in which highly conserved and plainly adaptive
behaviors of a circadian system can be understood in terms of the
straightforward responses of clock components to factors in the
environment of the organism.
QY: Jay C. Dunlap [jay.c.dunlap@dartmouth.edu]
(Science 7 Aug 98 281:825) (ScienceWeek 4 Sep 98)
-------------------
Related Background:
... ... *Neurospora: (pink bread mold) A genus of fungi grown in
culture and widely used in research in genetics and biochemistry.
-------------------
Related Background:
CIRCADIAN RHYTHMS IN HUMANS: EXTRA-VISUAL PHOTOTRANSDUCTION
... ... Campbell and Murphy (Cornell Univ., US) report
measurements of the response of the human circadian clock to
extraocular light exposure involving light pulses presented to
the popliteal region (the area behind the knee). They report a
systematic relation between the timing of the light pulse and the
magnitude and direction of clock phase shifts. The authors
suggest their findings challenge the belief that mammals are
incapable of extraretinal circadian phototransduction, and that
the findings also have implications for the development of more
effective treatments of sleep and circadian rhythm disorders.
QY: Scott S. Campbell, Cornell Univ. Medical College 212-746-1067
(Science 16 Jan 98) (ScienceWeek 30 Jan 98)
-------------------
Related Background:
DISSEMINATED INDEPENDENT CIRCADIAN CLOCKS IN THE FRUIT FLY
Drosophila melanogaster is a fruit fly that has been extensively
used in research in genetics, development, and molecular biology.
A transgenic Drosophila is a fruit fly into which genetic
material from another organism has been transferred, the
transferred and incorporated new genes then being expressed with
the resultant production of specific proteins. Bioluminescence is
the production of light in biological organisms, the process
usually involving the protein luciferin and the enzyme
luciferase. In molecular biology, a "promoter" is a DNA sequence
essential for the initiation of the transcription of RNA from a
particular gene sequence. Many organisms exhibit daily
(circadian) rhythms, cyclical variations in various bodily
functions, metabolisms, etc., even in constant light or constant
darkness. Such biological clocks are most easily studied in
simple organisms, but several clock genes have been identified
that have apparently been conserved in evolution and are present
in both simple organisms and higher forms such as mammals. Now
Plautz et al (4 authors at 2 installations, US) report that using
transgenic Drosophila expressing either luciferase or a green
fluorescent protein derived from the promotor of the clock gene
_period_ to monitor the circadian clock in various explanted body
parts reveals that such tissues show rhythmic bioluminescence
that can be reset by light. The authors suggest their results
show that autonomous circadian oscillators are present throughout
the body of Drosophila, that individual cells in Drosophila are
capable of supporting their own independent clocks, and that the
idea of a master oscillator controlling all other oscillators may
need to  be revised.
QY: Steve A. Kay, Scripps Research Inst. 619-784-1000
(Science 28 Nov 97) (ScienceWeek 19 Dec 97)
-------------------
Related Background:
IDENTIFICATION OF A MAMMALIAN CIRCADIAN RHYTHM GENE
Circadian rhythms are *biological rhythms based on a 24-hour
cycle apparently controlled by an endogenous biochemical clock.
The essential aspect is that if the environmental cues are
removed, the rhythm will continue for some time before the
periodicity degenerates. These rhythms are observed in both
primitive organisms and in mammals including humans, and in
primitive organisms as well as in insects, several genes have
been isolated that apparently are involved in the endogenous
clock process. Cheng-Chi Li et al (Baylor College of Medicine,
Houston TX US) have now isolated a gene in mice and humans that
is apparently similar to the "period" _per_ gene of the fruit fly
Drosophila melanogaster. Previous evidence shows the fruit fly
gene is switched on and off in a daily cycle, and with several
other genes produces the oscillating mechanism responsible for
the organism's diurnal clock. This is apparently the first
evidence that clock genes have been conserved through the course
of evolution.
QY: C-C. Li, Baylor College of Medicine (713) 798-4841
(Cell 19 Sep 97) (ScienceWeek 10 Oct 97)
-------------------
Related Background:
... ... *biological rhythms: Cyclic behaviors of various kinds
have been observed in organisms ranging from single-celled
protozoans and primitive plants to the most recently evolved
primates. In animals, an endogenous clock apparently exists in
the brain, and the light- sensitive production of the hormone
melatonin is evidently involved in this brain clock. Many
biologists believe primeval 13-hour tidal rhythms and monthly
lunar cycles influenced the clocks of primitive seashore
creatures, beginning the evolution of related biological clocks.
But of course the most significant periodicity to which the Earth
biosphere has always been exposed is the day-night light cycle,
and the term "circadian" technically applies only to this 24-hour
cycle.
-------------------
Related Background:
ANALYSIS OF MELATONIN ROLE IN HUMAN CIRCADIAN RHYTHMS
... In mammals, including humans, the biological clock apparently
resides in a group of neuron clusters in a part of the brain
called the hypothalamus, a region that responds to many chemical
inputs, including the hormone melatonin, an indole derived from
the metabolism of serotonin. Melatonin is secreted by another
hypothalamic brain structure, the pineal gland, which in turn is
stimulated by neurons in a nearby cluster (the suprachiasmatic
nucleus) that receives input from the retina of the eye. So this
is the apparent pathway in mammals: light on the retina,
electrical activity in the retino-hypothalamic tract, activity in
a hypothalamic region called the suprachiasmatic nucleus,
electrical signals to the pineal gland, secretion of the hormone
melatonin, action of melatonin on other neural structures in the
hypothalamus and elsewhere. In some insects, the biological clock
may be located in the optic lobes of the brain, and biological
clocks of one sort or another have been found at nearly all
levels of organism complexity. In humans, there is some evidence
that our biological clocks can be implicated in psychiatric
entities known as mood disorders, which is not surprising, since
the hypothalamus and nearby structures are known to play a key
role in emotions. But more generally, the biological clock is
apparent to anyone who has experienced jet-lag upon travelling
long distances east or west, the jet-lag effects resulting from
the body's biological clock being out of synch with the
light-dark cycle. The key question, of course, is that if
melatonin is involved in the workings of the human biological
clock, exactly how does it function? A number of laboratories
have been concerned with this problem, and this week Steven
Reppert et al (installations in MA, CT US) report that melatonin
apparently has two receptors, a major and a minor, and that the
result of binding to the minor receptor is a lowering of activity
in the suprachiasmatic nucleus, which seems to indicate a
chemical negative feedback loop. Identification of such feed-
back loops are the key to understanding brain function. The
studies were carried out on genetically altered mice lacking the
major melatonin receptor.
QY: S. Reppert, Harvard Med. School, Boston MA US (617) 432-1000
(Neuron 25 Jul 97) (ScienceWeek Reports 1 Aug 97)
-------------------
Related Background:
IDENTIFICATION OF A CLOCK GENE IN THE MOUSE
The unraveling of the molecular mechanisms of biorhythmicity
received new impetus recently. Two weeks ago Loros and Dunlap
reported the identification of two new clock genes in the bread
mold Neurospora, the genes chemically related to those already
known in Neurospora and also in the fruit fly, and now Joseph
Takahashi and his colleagues (Northwestern Univ., Evanston IL
US) report the identification of the first mammalian clock gene
in the mouse. Circadian rhythms in mice are precise, animals
kept in darkness beginning exercise on a treadmill each night
with a 23.7 hour cycle. The method used by Takahashi and his
group was to produce random chemical mutations of the entire
mouse genome until one mouse was found that had its clock
altered. Proceeding from there, the damaged gene was identified.
The gene's function was proved by repairing the clock in mutant
mice by substituting a correct piece of DNA. Of great interest
is the news that one domain of the mouse clock protein is the
same as a domain in the clock proteins of the fruit fly and
Neurospora, which supports the idea that circadian rhythms in
mammals have evolved from biochemical feedback loops in
primitive organisms.
(Cell 16 May) (Science-Week 22 May 97)
For more information: http://scienceweek.com/swfr.htm

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4. ZOOLOGY:
EMERGING INFECTIOUS DISEASES OF WILDLIFE
The past two decades have seen the emergence of pathogenic
infectious diseases, such as acquired immune deficiency syndrome
(AIDS), multi-drug resistant tuberculosis, and tick-borne
diseases, all of which represent a substantial global threat to
human health. Emergence is associated with a range of underlying
causal factors, including interactions with pathogens that infect
both animals and humans (zoonotic pathogens).
... ... P. Daszak et al (3 authors at 3 installations, US UK AU)
present a review of emerging infectious diseases that
predominantly affect wildlife, the authors making the following
points:
     1) Parallels between human and wildlife emerging infectious
diseases extend to early human colonization of the globe and the
dissemination of exotic pathogens. In the same way that Spanish
conquistadors introduced smallpox and measles to the Americas,
the movement of domestic and other animals during colonization
introduced their own suite of pathogens. The African *rinderpest
virus pandemic (*panzootic) of the late 1880s and 1890s is a
paradigm for the introduction, spread, and impact of virulent
exotic pathogens in wildlife populations. This highly pathogenic
*morbillivirus disease, endemic (enzootic) in Asia, was
introduced into Africa in 1889. The panzootic front traveled 5000
kilometers in 10 years, reaching the Cape of Good Hope by 1897,
killing more than 90 percent of Kenya's buffalo population and
causing secondary effects on predator populations dependent on
buffalo. Populations of some species remain depleted, and the
persistence of rinderpest in eastern Africa continues to threaten
bovid populations (cattle, antelopes, gazelles, goats, sheep,
etc.)
     2) Emerging infectious diseases of free-living wild animals
can be classified into three major groups on the basis of
epidemiological (epizootiological) criteria: a) Diseases
associated with "spill-over" from domestic animals to wildlife
populations living in proximity. b) Diseases related directly to
human intervention, via host or parasite translocations. c)
Diseases with no overt human or domestic animal involvement. The
authors suggest these phenomena have two major biological
implications: a) many wildlife species are reservoirs of
pathogens that threaten domestic animal and human health; and b)
wildlife emerging infectious diseases pose a substantial threat
to the conservation of global diversity.
     3) The authors tabulate the following emerging infectious
diseases that involve humans, domestic animals, and wildlife:
... ... a) Hendra virus disease: Hendra virus (*paramyxovirus)
infecting humans and horses, with a fruit bat reservoir. Emergent
in Australia and Papua New Guinea.
... ... b) Nipah virus disease: Nipah virus (paramyxovirus)
infecting humans, domestic pigs and domestic dogs, and fruit
bats. Emergent in Malaysia and Singapore.
... ... c) Cryptosporidiosis: Cryptosporidium parvum (a protozoan
parasite) infecting humans, cattle, wild rodents, and other
mammals. Emergent in Europe and US.
     4) The authors tabulate the following emerging infectious
diseases that involve only humans and wildlife:
... ... a) Hantavirus pulmonary syndrome: Various strains of
*hantavirus (bunyaviruses) infecting humans and rodents. Emergent
in Americas, especially southwestern US.
... ... b) Marburg virus and Ebola virus hemorrhagic fever:
Marburg and Ebola virus (*filoviruses) infecting humans and
nonhuman primates, with an insectivorous or fruit bat reservoir
suspected. Emergent in sub-Saharan Africa, Indonesia,
Philippines.
... ... c) Human *ehrlichiosis: Several species of tick-borne
*rickettsiae infecting humans, deer (Cervidae), horses, dogs, and
other animals. Emergent in US, Europe, Africa.
... ... d) Plague: *Yersinia pestis (bacterium) infecting humans
and a wide range of mammalian hosts (especially rodents).
Emergence is panglobal, especially India and southwestern US.
-----------
P. Daszak et al: Emerging infectious diseases of wildlife --
threats to biodiversity and human health.
(Science 21 Jan 00 287:443)
QY: Peter Daszak [daszak@uga.edu]
-----------
Text Notes:
... ... *rinderpest virus: "Rinderpest" is an acute, contagious,
and often fatal virus disease of cattle, sheep, and goats, the
disease characterized by fever and the appearance of ulcers in
the mucous membranes of the intestinal tract.
... ... *panzootic: The terms panzootic, epizootic, enzootic are
more or less synonymous with pandemic, epidemic, endemic,
respectively, but since the root of the latter group is the Greek
"demos", meaning "people", some authors choose to reserve the
-demic forms for descriptions of human diseases, and use the
-zootic forms for diseases of animals. Apart from this
difference, the respective meanings are in fact identical.
... ... *morbillivirus: The morbilliviruses are a subgroup of the
paramyxoviruses, the morbillivirus genus containing the measles
virus (rubella) of humans, as well as canine distemper virus,
rinderpest virus of cattle, and aquatic morbilliviruses that
infect marine mammals.
... ... *paramyxovirus: These viruses include the most important
agents of respiratory infections of infants and young children,
as well as the causative agents of mumps and measles. In general,
paramyxoviruses are 150 to 300 nanometers in diameter, the viral
genome a linear single-stranded RNA molecule of 16 to 20
kilobases.
... ... *hantavirus: (Hanta pulmonary syndrome; Sin Nombre virus)
Hantaviruses are classified as a subtype of bunyaviruses, which
are spherical particles containing a single-stranded RNA genome
11 to 21 kilobases in size. In general, the bunyaviruses are one
of several pathogens involved in rodent-borne hemorrhagic fevers
worldwide. The virus measures 80 to 120 nanometers. Hantavirus
pulmonary syndrome is newly recognized in the US, the pathogen
transmitted by deer mice, the disease apparently 60 percent
fatal.
... ... *filoviruses: These viruses are polymorphic (pleomorphic)
particles, appearing as long filamentous threads or as odd-shaped
forms. The known filoviruses are Marburg virus and Ebola virus.
The large genome is single-stranded RNA and contains 7 genes.
These viruses are highly virulent and infections usually end in
death.
... ... *ehrlichiosis: The ehrlichiae are obligate intracellular
bacteria which are taxonomically grouped with the rickettsiae.
The clinical manifestations of the various ehrlichioses are
similar to Rocky Mountain spotted fever without the rash. Most
ehrlichiae are pathogens of animals.
... ... *rickettsiae: In general, "rickettsiae" are a type of
small bacteria that usually occur in the cytoplasm of cells of
lice, fleas, ticks, and mites. Some species of rickettsiae are
parasitic in humans, causing epidemic typhus, murine typhus,
Rocky Mountain spotted fever, and other diseases.
... ... *Yersinia pestis: Plague, also called bubonic plague or
"Black Death", is a disease with a notorious history. It is
caused by the bacillus Yersinia pestis, which infects wild
rodents. The bubonic variant of the disease is transmitted to
humans from rodents by the bite of an infected flea. Human to
human transmission occurs by inhalation of respiratory droplets
spread by the cough of patients with plague who have developed
pulmonary lesions, and the result of this is "primary pneumonic
plague", which differs from "bubonic plague" in that bubonic
plague affects the lymph nodes, among other tissues (producing
"buboes", lymph node swellings). The last plague pandemic began
in Hong Kong in 1894 and spread throughout the world. Plague
still exists as an endemic disease in many parts of the world,
including the southwestern U.S.
-------------------
Summary & Notes by SCIENCE-WEEK http://scienceweek.com 19May00
For more information: http://scienceweek.com/swfr.htm

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5. MEDICAL BIOLOGY:
A REVIVAL OF ELECTROSHOCK THERAPY
     Electroshock (electroconvulsive therapy) in the treatment of
mental illness has had a checkered history. In 1934, clinical
psychiatrists discovered that the injection of certain drugs
produced convulsive seizures, and that after such seizures
certain mental patients often exhibited a remarkable amelioration
of symptoms. In 1938, electric current, instead of drugs, was
first used as therapy to induce such seizures, and since
undesirable physical effects were less with electrically induced
seizures than with drug-induced seizures, electroconvulsive
therapy became the procedure of choice. Between 1938 and the
1960s, electroshock was widely used in the treatment of
depression, mania, and other mental disorders. As was apparent
early on, when electroconvulsive therapy ameliorates symptoms in
a patient, it is the neurological seizure which produces the
amelioration, and not the electric current or the drug per se,
the neurological seizure characterized by simultaneous activation
of large groups of neurons in the brain and spinal cord. Until
recently, the most common unwanted side effect of electroshock
has been moderate to severe memory loss, with side effects in
general sometimes reversible and sometimes not reversible.
     In the 1960s, with the advent of psychotropic drugs in the
treatment of mental illness, and a developing negative public
attitude toward electroconvulsive therapy provoked by the media
and a growing number of mental health professionals who opposed
the procedure, electroconvulsive therapy rapidly went out of
fashion. In 1973, the California legislature banned the use of
electroconvulsive therapy. Currently, in California, Texas, and
Tennessee, electroconvulsive therapy is prohibited in children
and young adolescents, and in certain other states
electroconvulsive therapy may be used only after physicians and
independent consultants certify that all other methods of
treatment have been tried and have failed.
     In the view of a substantial segment of the public and of
many mental health professionals, the fundamental problem with
electroshock as a therapeutic procedure in mental illness is that
when the treatment works there is no satisfactory theory of why
it works, i.e., there is no rational basis for the treatment, and
since the treatment involves an intense and apparently violent
physical assault on the central nervous system, many people view
the treatment as equivalent to kicking, shaking, and slamming a
vending machine with a sledgehammer in order to get the machine
to behave -- a "treatment" that also sometimes works, but which
also often permanently damages the machine. And of course the
problem with electroshock is compounded by the fact that mental
patients are often not rational enough to provide informed
consent to such a treatment -- or to any other treatment of their
condition.
     Nevertheless, electroconvulsive therapy is currently applied
to approximately 100,000 patients each year in the US, and many
more worldwide, and there is apparently a renewed interest in the
procedure as a treatment for certain types of mental dysfunction.
... ... Max Fink (State University of New York Stony Brook, US),
author and editor of several textbooks and a journal devoted to
electroconvulsive therapy in mental illness, presents a review of
electroconvulsive therapy, the author making the following
points:
     1) The author states that the array of treatment
modifications that have been introduced in electroconvulsive
therapy -- muscle relaxation, anesthesia, continuous oxygenation,
brief-pulse currents, selected electrode placements, energy
dosing, and monitoring the body's physiology during each
treatment -- have changed the impact of electroshock on memory so
markedly that "when patients now recover from an illness, they
are usually able to recall the events that occurred before their
illness and to utilize the skills of their education and training
with the same ability as others of their age and experience." The
author suggests that in its present use electroconvulsive therapy
is considered as safe as psychotropic medicines, and that for the
elderly, for those weakened by systemic diseases, and for
pregnant women with severe mental illnesses, electroconvulsive
therapy is safer than the alternative treatments.
     2) The author points out that at present in the US there is
an uneven distribution of facilities providing electroconvulsive
therapy. Most university hospitals treat approximately 5 to 10
percent of their mentally ill adult patients with
electroconvulsive therapy, whereas the treatment rates at state,
federal, and Veterans Administration are much lower because few
have the facilities. Community and private hospitals vary widely
in their ability to offer the treatment.
     3) The author poses the question: "Why are seizures, which
are dangerous and damaging when they occur spontaneously,
beneficial when induced experimentally?" And the author answers
the question: "For the moment, scientists have no answer to this
question -- we simply don't understand how electroconvulsive
therapy has the restorative capacity that it does. For that
matter, no hypothesis for the mode of action of any psychiatric
treatment -- be it electroshock, psychotropic medicines, or the
'talk' therapies -- is satisfactory."
-----------
Max Fink: Electroshock revisited.
(American Scientist Mar-Apr 2000 88:162)
QY: Max Fink [fink@lij.edu]
-------------------
Summary by SCIENCE-WEEK http://scienceweek.com 19May00
For more information: http://scienceweek.com/swfr.htm

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6. PUBLIC HEALTH:
PREVENTION OF MOTHER-TO-CHILD HIV TRANSMISSION
Each year an estimated 590,000 infants acquire *human
immunodeficiency virus type 1 (HIV-1) infection from their
mothers, mostly in developing countries that are unable to
implement interventions now standard in the industrialized world.
In resource-poor settings, the HIV *pandemic has eroded modern
gains in infant and child survival. Recent clinical trial results
from international settings suggest that short-course
*antiretroviral drug therapy regimens could significantly reduce
perinatal HIV transmission worldwide if research results could be
translated into practice.
... ... K.M. De Cock et al (9 authors at 2 installations, US and
World Health Organization) present a review of current knowledge
of mother-to-child HIV transmission in developing countries, the
authors making the following points:
     1) By the end of 1998, approximately 33.4 million people
were living with HIV worldwide, including 22.5 million (67
percent) in sub-Saharan Africa. In 1998, 590,000 new pediatric
infections occurred (10 percent of total new infections), almost
all from mother-to-child transmission. Of these new pediatric
infections, 90 percent were in Africa. Of the 2.5 million
acquired immunodeficiency syndrome (AIDS) deaths in 1998,
approximately 510,000 (20 percent) occurred in children less than
age 15 years. Infant and child mortality rates in east and
southern Africa are now one-third to two-thirds higher than they
would have been in the absence of AIDS, contributing to the
progressive reduction in life expectancy in this region.
     2) The authors point out that the global epidemiology of
pediatric HIV infection reflects the epidemiology of HIV in
women: More than 80 percent of the 13.8 million women living with
HIV by the end of 1998 were African. In several urban centers in
eastern and southern Africa, HIV infection rates in pregnant
women now exceed 25 percent. In Africa and Asia, where
heterosexual transmission of HIV is the dominant mode of spread,
nearly 2 million children of HIV-infected parents are now
orphaned annually (having lost the mother or both parents).
Households headed by grandparents and children are the new
reality in areas of high HIV prevalence, and the physical and
social welfare of AIDS orphans in developing countries is now a
major problem.
     3) The authors point out that current treatment procedures
have resulted in two distinct HIV epidemics: In industrialized
countries, impressive reductions in HIV-related disease and death
have occurred, so virtual elimination of new pediatric infections
is feasible; in contrast, developing countries face increasing
levels of infection, disease, and death due to HIV. The authors
suggest that prevention of HIV infection in children requires HIV
and AIDS to be addressed as a disease of the family and
community, which leads to consideration of other interventions,
such as reproductive health care for women and support for
children orphaned by the epidemic.
     4) The authors conclude: "Few other aspects of HIV research
have demonstrated results as dramatic as the *perinatal
prevention trials. If international research is to serve any
purpose, then the results of the short-course antiretroviral
trials for preventing mother-to-child HIV transmission must lead
to public health action now."
-----------
Kevin M. De Cock et al: Prevention of mother-to-child HIV
transmission in resource-poor countries.
(J. Amer. Med. Assoc. 1 Mar 00 283:1175)
QY: Kevin M. De Cock [kmd2@cdc.gov]
-----------
Text Notes:
... ... *human immunodeficiency virus type 1 (HIV-1): HIV-1 is
the subtype of HIV (human immune-deficiency virus) that causes
most cases of AIDS in the Western Hemisphere, Europe, and
Central, South, and East Africa. HIV is a retrovirus (subclass
lentivirus), and retroviruses are single-stranded RNA viruses
that have an enzyme called reverse transcriptase. With this
enzyme the viral RNA is used as a template to produce viral DNA
from cellular material. This DNA is then incorporated into the
host cell's genome, where it codes for the synthesis of viral
components. HIV should be distinguished from AIDS. Acquired
immunodeficiency syndrome (AIDS) is a secondary immunodeficiency
syndrome resulting from HIV infection and characterized by
opportunistic infections, malignancies, neurologic dysfunction,
and a variety of other syndromes.
... ... *pandemic: In general, the term "pandemic" refers to any
extensive epidemic occurring over a wide geographic area and
affecting a relatively large proportion of the population.
... ... *antiretroviral drug therapy: HIV is a retrovirus (see
note above re HIV-1.)
... ... *perinatal: Referring to before, during, or immediately
after birth.
-------------------
Summary & Notes by SCIENCE-WEEK http://scienceweek.com 19May00
For more information: http://scienceweek.com/swfr.htm
-------------------
Related Background:
EPIDEMIOLOGY: ON THE AIDS EPIDEMIC
Although in the US the AIDS epidemic long ago lost its starring
role as a major media event, the epidemic is still a major
medical event in the US and elsewhere, and one with enormous
potential and actual consequences for entire populations of
people on the planet.
... ... Anthony S. Fauci (National Institutes of Health, US)
reviews the current situation concerning the international AIDS
epidemic, the author making the following points:
     1) Concerning infectious diseases, this century has
witnessed two unexpected cataclysmic events. The first, the
*influenza A *pandemic of 1918, was due to an old but reemerging
microbe. Influenza had been a problem for centuries, but in that
one winter of 1918-1919 it was responsible for the deaths of
approximately 25 million people worldwide and 550,000 people in
the US. The other pandemic, the acquired immunodeficiency
syndrome (AIDS), is due to a newly recognized microbe, the human
immunodeficiency virus (HIV). The world first became aware of
this new disease in the summer of 1981, and it has exploded in
successive waves in various regions of the world.
     2) Recent molecular epidemiological data have clearly
indicated that *HIV type 1 (HIV-1) evolved with the Pan
troglodytes troglodytes subspecies of chimpanzee and was present
in that subspecies for centuries. The virus apparently does not
readily cause disease in the chimpanzee.
     3) The most likely mechanism of transmission of HIV-1 from
chimpanzees to humans was by contamination of a person's open
wound with the infected blood of a chimpanzee, probably when the
chimpanzee was being butchered for the purposes of consumption.
Chimpanzees have traditionally served as a source of nutrition
for humans in certain parts of sub-Saharan Africa.
     4) AIDS continues to exact an enormous toll throughout the
world in both human and economic terms. In the US, an estimated
650,000 to 900,000 people are infected with HIV, of whom more
than 200,000 are unaware of their infection. Through 1998,
688,200 cumulative cases of AIDS and 410,800 AIDS related deaths
had been reported to the US Centers for Disease Control and
Prevention (CDC).
     5) The magnitude of the world epidemic is huge. As of the
end of 1998, there were more than 33 million people worldwide
with HIV infection or AIDS, with an estimated 43 percent of them
female. An estimated 5.8 million new HIV infections occurred
worldwide during 1998 -- approximately 16,000 each day. More than
95 percent of these new infections occurred in developing
countries. In 1998, HIV infection or AIDS was the 4th leading
cause of death worldwide, resulting in an estimated 2.3 million
deaths. If the current trend in the incidence of HIV infection
continues, more than 40 million people will be infected with HIV
as we enter the new millennium.
     6) In addition to the enormous human tragedy associated with
HIV and AIDS, the economic costs of the epidemic are staggering,
posing a serious impediment to the growth and economic stability
of many developing countries. It is also clear that this epidemic
will produce political instability in some nations and in
communities within these nations.
     7) The author concludes: "The HIV pandemic has posed a
formidable challenge to the biomedical research and public health
communities of the world. What began as a handful of recognized
cases among homosexual men in the United States has become a
global pandemic of such proportions that it clearly ranks as one
of the most destructive microbial scourges in history. We are at
pivotal point in the evolution of this historic event as we enter
the new millennium. Biomedical research has provided the tools
for the development of treatments as well as a still elusive
vaccine. It has become apparent over the past few years that
minimizing the destructive impact of this epidemic will require
partnerships between the public and private sectors as well as a
stronger political will among the nations of the world. Unless
methods of prevention, with or without a vaccine, are successful,
the worst of the global pandemic will occur in the 21st century."
-----------
Anthony S. Fauci: The AIDS epidemic: Considerations for the 21st
century.
(New England J. Med. 30 Sep 99 341:1046)
QY: Anthony S. Fauci [afauci@niaid.nih.gov]
-----------
Text Notes:
... ... *influenza A: The influenza viruses are of the group of
orthomyxoviruses, and all known orthomyxoviruses are influenza
viruses. There are 3 immunological types, known as A, B, and C.
The "myxovirus" name implies an affinity for certain glycoprotein
(mucin) cell surface receptors. Influenza virus particles are
usually spherical and approximately 100 nanometers in diameter.
The influenza A virus has a single-stranded RNA genome.
... ... *pandemic: See main report notes.
... ... *HIV type 1 (HIV-1): See main report notes.
-------------------
Summary & Notes by SCIENCE-WEEK http://scienceweek.com 5Nov99
For more information: http://scienceweek.com/swfr.htm

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IN FOCUS: ON EVOLUTIONARY THEORY AND THE SOCIAL SCIENCES
"At least since the time of Darwin, there has been a tradition of
borrowing between evolutionary theory and the social sciences.
Darwin himself owed a debt to the Scottish economists who showed
him how order can be produced without conscious design. Adam
Smith thought that socially beneficial characteristics can emerge
in a society as if by an 'invisible hand'; though each individual
acts only in his or her own narrow self-interest, the result,
Smith thought, would be a society of order, harmony, and
prosperity. The kind of theory Darwin aimed at -- in which
fitness improves in a population without any conscious guidance
-- found a suggestive precedent in the social sciences. The use
of game theory by Maynard Smith and others provides a
contemporary example in which an idea invented in the social
sciences finds application in evolutionary theory. Economists and
mathematicians were the first to investigate the payoffs that
would accrue to players following different strategies in games
of a given structure. Biologists were also to see that game
theory does not require that the players be rational or even that
they have minds. The behavior of organisms exhibits regularities;
this is enough for us to talk of them as pursuing strategies. The
payoffs of the behaviors that result from these strategies can be
measured in the currency of fitness -- i.e., in terms of their
consequences for survival and reproduction. This means that the
idea of payoffs within games allows us to describe evolution by
natural selection. Here again is a case in which a social
scientific idea has broader scope than its initial social science
applications might have suggested."
-----------
Elliot Sober: "Models of Cultural Evolution"
in: P. Griffiths (ed.): _Trees of Life: Essays in the Philosophy
of Biology_ (Australian Studies in the History and Philosophy of
Science) (Kluwer Academic Publishers, 1991, p.17)

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