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ScienceWeek
SCIENCE-WEEK
SCIENCE-WEEK - Part 1/3
A Free Weekly Digest of the News of Science
April 24, 1998
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One thing I have learned in a long life: that all our science,
measured against reality, is primitive and childlike -- and yet
it is the most precious thing we have.
-- Albert Einstein
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Contents of This Issue:
Part 1:
1. Criticism of Undergraduate Education at Research Universities
2. Mathematician Alberto Calderon Dead at 77
3. Cosmic Rays and the Origin of the Light Elements
4. Birth and Early Evolution of a Planetary Nebula
5. Details of a Proposal for a Quantum Theory Without Observers
Part 2:
6. Light-Driven Enzyme Production of ATP in Artificial Membrane
7. Rotation of Myosin Light Chain Domain on Muscle Contraction
8. On Heterochrony as a Dominant Mode of Developmental Evolution
9. Free Calcium Level Changes Induced by Elastin Peptides
10. Evidence for Intact Synaptic Vesicles in Endocytotic Cycle
Part 3:
11. Functional Anatomy of Human Music Processing
12. Classical Conditioning and Brain Systems: Role of Awareness
13. Red Cell Viability in Red Cell Aging and Hemolytic Anemia
14. Centrosome Hypertrophy in Human Breast Tumors
15. Risks to the Fetus of Prescription and Over-the-Counter Drugs
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1. CRITICISM OF UNDERGRADUATE EDUCATION AT RESEARCH UNIVERSITIES
A new report by the Carnegie Foundation for the Advancement of
Teaching (US) criticizes the leading research universities in the
US as shortchanging their undergraduate students by consigning
undergraduates to classes taught by graduate assistants and by
failing to provide students with "a coherent body of knowledge"
by the time they graduate. The report calls for an end to the
division between teaching and research, and for the involvement
of undergraduates in research beginning in their first university
year. The report was prepared by an 11-member commission from the
National Academy of Sciences, the Carnegie Foundation, the
American Council on Education, the Corporation for Public
Broadcasting, and 5 different research universities. Milton
Glaser, a designer and graphic artist, is also listed as a member
of the commission. The title of the report is "Reinventing
Undergraduate Education: A Blueprint for America's Research
Universities". Among the proposals in the report: 1) rewarding
faculty members more for good teaching; 2) using technology more
creatively; 3) fostering more interdisciplinary work; 4) placing
freshmen in small groups where they live together and take
courses together; 5) getting undergraduate students involved in
research with senior faculty members; 6) requiring undergraduate
students to conduct original research. Shirley Strum Kenny (State
University of New York Stony Brook), chairwoman of the
commission, says, "What we need to do is create a culture of
enquirers rather than a culture of receivers."
(New York Times 20 Apr 98) (Science-Week 24 Apr 98)
2. MATHEMATICIAN ALBERTO CALDERON DEAD AT 77
Alberto Calderon, a leading mathematician specializing in
mathematical analysis, died on April 16th in Chicago at the age
of 77. Calderon was a protege of Antoni Zygmund, with whom he
founded what is called the Chicago school of analysis, from which
emerged the Calderon-Zygmund theory of singular integrals and
development of the link between Fourier analysis and partial
differential equations, a link that has been of considerable
significance in the study of many physical systems. A "singular
integral" is a non-generic solution to a differential equation,
i.e., a solution not obtainable from the general solution. Many
mathematicians consider the work of the Calderon-Zygmund school
"one of the most important developments in analysis in the 20th
century." Calderon received the Wolf Prize, the highest award in
mathematics, in 1989.
(New York Times 20 Apr 98) (Science-Week 24 Apr 98)
3. COSMIC RAYS AND THE ORIGIN OF THE LIGHT ELEMENTS
Cosmic rays are highly energetic particles moving at close to the
speed of light and continuously bombarding the Earth's atmosphere
from all directions. The energies of the particles are enormous
and range from 10^(8) to over 10^(19) electronvolts. The term
"highest energy cosmic rays" refers to cosmic rays with energies
of the order of 10^(20) electronvolts or greater, apparently from
extra-galactic sources, but the origins are not clear. Gamma rays
are extremely high energy electromagnetic radiations with wave-
lengths approximately 0.01 nanometers or less. Supernovas are
stellar explosions of stars with original masses greater than
about 3 solar masses, the explosions of great brilliance and
occurring in the end stages of a star's evolution. The halo stars
of our Galaxy are spherically distributed stars associated with
the Galaxy but external to the flattened spiralized Galactic
disk. The halo stars are evidently old stars that formed early in
the history of the Galaxy. ... ... Ramaty et al (3 authors at 3
installations, US IL) review the involvement of cosmic rays and
nuclear gamma rays in the origin of the light elements. The fact
that the early Galaxy was almost totally devoid of carbon and
heavier elements, containing mostly hydrogen and helium produced
in the Big Bang, has very important implications for the origin
of both early and contemporary cosmic rays. Recent observations
of lithium, beryllium, and boron abundances in halo stars formed
in the early Galaxy have shed new light on the source of cosmic
rays, and the data support the idea that the bulk of carbon and
heavier elements in cosmic rays are particles accelerated from
the ejecta of supernovas.
QY: Reuven Ramaty, Goddard Space Flight Cntr, Greenbelt, MD (US)
(Physics Today April 1998) (Science-Week 24 Apr 98)
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Related Background:
ENERGETIC COSMIC RAYS MAY BE IRON NUCLEI
The cosmic microwave background is black-body radiation (the
emission radiation of a perfect absorber of radiation) at a
present temperature of 2.73 degrees Kelvin, and has an almost
equal intensity in all directions in space. (The deviations from
isotropic intensity, however, are of extreme importance in
theoretical cosmology.) Infrared radiation is electromagnetic
radiation lying between the radio and the visible bands of the
spectrum (and intermediate in energy between these bands), and
important sources of cosmic infrared radiation are the shells of
dust grains surrounding stars, the shells heated by the star's
visible and ultraviolet radiation. Cosmic rays are particles with
a distant and often extra-galactic origin; they strike the
Earth's atmosphere and produce a shower of new particles detected
on the Earth's surface. One important question in cosmic ray
physics is why there should be so many events with total energies
above 10^(20) eV. The problem is that if a primary particle were
journeying from a distant galaxy, the energy of the particle
ought to be sapped by interactions with cosmic microwave
background photons or with infrared background radiation. There
is the additional problem of how cosmic rays with even higher
energies could have been accelerated to such initial energies in
the first place. ... ... Now Floyd Stecker (Goddard Space Flight
Center, US) has evidently determined that a particle with an
energy of 2 x 10^(20) eV that started out as an iron nucleus
could indeed negotiate a 300-million-light-year journey through
the infrared background radiation. The nucleus would partially
disintegrate en route, but would still arrive at Earth with the
energy of cosmic rays. QY: Floyd Stecker, Goddard Space Flight
Center, US.
(Phys. Rev. Lett. 2 Mar 98) (Amer. Inst. Phys. Bulletin #364)
(Science-Week 10 Apr 98)
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Related Background:
ON HIGHEST ENERGY COSMIC RAYS
... Pions (or pi-mesons) are subatomic particles with masses
approximately 270 times the mass of the electron. The term "pion
production losses" refers to the losses of energy of cosmic rays
particles as they interact with the Earth's atmosphere at about
20 kilometers to produce pions and the subsequent pion decay
products of electrons and photons. The term "grand unification
energy" refers to the energy above which (according to the grand
unification theories) the fundamental forces are related through
symmetry, with the fundamental forces comprising the
gravitational force, the electromagnetic force, the nuclear
strong force, and the nuclear weak force. O'Halloran et al (3
authors at 3 installations, US JP), in a review of current work
in highest energy cosmic ray physics, outline the various
projects planned for the near future at various installations,
and predict the next decade will provide important data in this
field. The authors suggest that if the observed cosmic energy
spectrum is not cut off by pion- production losses, but instead
the spectrum continues on to energies approaching the grand
unification energy of the order of 10^(23) eV, "twists and turns
in astrophysical theory" will be required to explain the results.
QY: Thomas O'Halloran, Univ. Illinois Urbana-Champaign
217-333-3090.
(Physics Today January 1998) (Science-Week 16 Jan 98)
4. BIRTH AND EARLY EVOLUTION OF A PLANETARY NEBULA
White dwarf stars are extremely dense and compact stars that have
undergone gravitational collapse. White dwarfs are of great
interest to cosmologists, because it is believed their masses and
luminosities have little variance and they can thus be used as
"standard candles" to estimate distances. The final expulsion of
a gas by a star as it forms a planetary nebula (the ionized shell
of gas often observed surrounding a young white dwarf star) is
one of the most poorly understood stages of stellar evolution.
Particularly puzzling is how a spherical star can produce a
highly asymmetric nebula with collimated outflows (outflows
aligned parallel to a particular axis). ... ... Bobrowsky et al
(4 authors at 4 installations, US IN ES) now report optical
observations of the nebula surrounding the star He3-1357 (called
by the authors the "Stingray nebula"), a nebula that has
evidently become an ionized planetary nebula within the past few
decades. The authors find that the collimated outflows are
already evident, and they have identified the nebular structure
that focuses the outflows, and have also found a companion star,
which reinforces previous suspicions that binary companions play
an important role in shaping planetary nebulas and in changing
the direction of successive outflows. The authors suggest the
Stingray nebula demonstrates how far the nebular structure can
develop by the time the nebula becomes ionized, and that no other
planetary nebula in this phase of its evolution has been
previously identified.
QY: Matthew Bobrowsky (mattb@cta.com)
EMAIL
(Nature 2 Apr 98) (Science-Week 24 Apr 98)
5. DETAILS OF A PROPOSAL FOR A QUANTUM THEORY WITHOUT OBSERVERS
S. Goldstein, in the second part of a review of the current state
of the development of a quantum theory without observers, makes
the following points: 1) Several current quantum theories without
observers are completely well defined and hence provide a
conclusive refutation of Bohr's claim that such a theory is
impossible. 2) The paradoxes of quantum theory can be resolved in
a surprisingly simple way: by insisting that particles always
have positions and that they move in a manner naturally suggested
by the Schroedinger equation (e.g., the quantum mechanics of
David Bohm as amplified by John Bell). 3) The possibility of a
deterministic reformulation of quantum theory has been regarded
by many physicists as having been conclusively refuted,
particularly by the 1932 refutation of John von Neumann, but the
von Neumann proof is false, and subsequent "refutations" are not
convincing. 4) Bohmian mechanics is by far the simplest and
clearest version of quantum theory. 5) Although none of the
quantum theories without observers is Lorentz invariant, the
author believes such a theory is possible, and that the three
approaches of decoherent histories (which assumes the wave
function is not a complete description of a physical system),
spontaneous localization (which assumes spontaneous and random
collapse of wave functions), and Bohmian mechanics (which assumes
the wave function provides only an incomplete description of a
system and governs the motion of more fundamental variables) have
much to teach us about finding such a theory. QY: Sheldon
Goldstein, Dept. of Mathematics, Rutgers University New Brunswick
908-932-8789.
(Physics Today April 1998 v51:n4:p38) (Science-Week 24 Apr 98)
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Related Background:
ON QUANTUM THEORY WITHOUT OBSERVERS
One of the fundamental questions of physics is whether pure
states (i.e., states undisturbed by avoidable noise) are states
such that the outcome of every measurement can be exactly
predicted. Classical physics is based on the proposition that the
answer to the question is yes. Orthodox quantum mechanics is a
theory based on the proposition that the answer is no, and that
we can only make precise quantitative statements about probab-
ilities, the limitation due to an essential interaction between
the observer and that which is being measured.
... ... S. Goldstein (Rutgers University New Brunswick, US), in
the first of a two-part review, discusses the idea of quantum
theory without observers, and suggests that despite the claims of
most of the originators of quantum theory, the appeal at a fund-
amental level to observers and measurement, which is so prominent
in orthodox quantum theory, is not needed to account for quantum
phenomena. Referring to the classical Bohr-Einstein debate,
Goldstein says the debate has already been resolved in favor of
Einstein. What Einstein desired and Bohr held impossible -- an
observer-free formulation of quantum mechanics in which the
process of measurement can be analyzed in terms of more fund-
amental concepts, does in fact exist, and there are many such
formulations, several of which have the potential to become a
serious program for the construction of a quantum theory without
observers. QY: Sheldon Goldstein, Rutgers University New
Brunswick 908-932-8789.
(Physics Today March 1998) (Science-Week 20 Mar 98)
(continued in Part 2)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
SCIENCE-WEEK - Part 2/3
A Free Weekly Digest of the News of Science
April 24, 1998
Contents of Part 2:
6. Light-Driven Enzyme Production of ATP in Artificial Membrane
7. Rotation of Myosin Light Chain Domain on Muscle Contraction
8. On Heterochrony as a Dominant Mode of Developmental Evolution
9. Free Calcium Level Changes Induced by Elastin Peptides
10. Evidence for Intact Synaptic Vesicles in Endocytotic Cycle
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6. LIGHT-DRIVEN ENZYME PRODUCTION OF ATP IN ARTIFICIAL MEMBRANE
Energy transducing membranes of living organisms couple
spontaneous to non-spontaneous processes via a protonmotive
force, an imbalance in electrochemical potential of protons
across the membrane. In most organisms, this protonmotive force
is generated by redox reactions that are either photochemically
driven (e.g., photosynthetic reaction centers) or intrinsically
spontaneous (e.g., oxidative phosphorylation in mitochondria).
Liposomes are artificial vesicles (spherules) in which lipid
molecules are spontaneously arranged into bilayers with hydro-
philic groups exposed to water molecules both outside the vesicle
and in the core. ... ... Steinberg-Yfrach et al (6 authors at 2
installations, US FR) report the incorporation of an ATP-synthase
into liposomes containing the components of the proton-pumping
photocycle, and that irradiation of this artificial membrane
system with visible light results in the synthesis of ATP against
an ATP chemical potential of approximately 12 kilocalories per
mole, with a quantum yield of more than 7%. The authors suggest
this system mimics the process by which photosynthetic bacteria
convert light energy into an ATP chemical potential, and that the
assembly of an artificial photosynthetic membrane that
demonstrates net energy conservation opens the door to the design
of systems in which energy-requiring biological and biomimetic
processes in model cell systems can be driven by a photocyclic
energy source.
QY: Thomas A. Moore (tmoore@asu.edu)
EMAIL
(Nature 2 Apr 98) (Science-Week 24 Apr 98)
7. ROTATION OF MYOSIN LIGHT CHAIN DOMAIN ON MUSCLE CONTRACTION
Actin is a family of ubiquitous structural proteins present in
all eukaryote cells, and myosin is the predominant structural
protein found in muscle and other contractile structures. In
muscle cells, myosin is in association with actin, and myosin
"heads" are essentially bridges between mysoin filaments and the
actin complex. Muscle contraction results from the relative
sliding between actin and myosin filaments, and most models
suggest that filament sliding is driven by a large structural
change of actin-bound myosin heads. However, resolving distinct
myosin structural states has been difficult, since active muscle
contains an apparently heterogeneous population of myosin heads
that independently cycle through different structural states.
... ... Baker et al (5 authors at University of Minnesota, US),
using electron paramagnetic resonance techniques, report
observing two distinct orientations of spin label attached
specifically to a single site on the light chain domain of myosin
in relaxed scallop muscle fibers. The results indicate that a
fraction of myosin heads undergoes a large (at least 30 deg.)
axial rotation of the myosin light chain domain upon force
generation and muscle contraction. The authors suggest the
resulting model helps explain why this observation has been so
elusive and provides insight into the mechanisms by which motor
protein structural transitions drive molecular motility. They
also suggest that these results support a new framework for
exploring energy transduction systems, in which molecular engines
work by modulating a distribution between existing structural
states through ligand binding and protein-protein interactions,
rather than by driving new structures that are directly coupled
to the bound ligand.
QY: David D. Thomas (ddt@ddt.biochem.umn.edu)
EMAIL
(Proc. Natl. Acad. Sci. US 17 Mar 98 v95:p2944)
(Science-Week 24 Apr 98)
-------------------
Related Background:
MOTOR PROTEINS AND ORGANELLE TRANSPORT
The interior of a living cell is a dynamic system involving a
dynamic supporting matrix, active synthesis and degradation of a
variety of small and large molecules, and the regulated transport
of various molecular species to local and remote sites within the
cell. Research during the past two decades has provided revel-
ations concerning the molecular biology of a variety of orchestr-
ated movements with the cell interior, particularly movements
producing the transport of cell organelles (organized subsyst-
ems). "Motor proteins" are mechanico-chemical enzymes involved in
locomotion or transport, and there are three families of such
proteins: kinesins, dyneins, and myosins. Kinesins and dyneins
are microtubule based motor proteins, while myosin is a micro-
filament based motor protein. In general, as mechanico-chemical
enzymes, motor proteins convert energy from hydrolysis of nucleo-
tides to mechanical force, and since they are involved in many
important cellular events, the molecular details are currently
the focus of intensive research. ... ... N. Hirokawa (University
of Tokyo, JP) reviews the molecular mechanisms of organelle
transport in cells, particularly the role of the motor proteins
kinesin and dynein. The author suggests that in the near future
we will fully understand how the cell sorts and transports
proteins and lipids to their appropriate intracellular
destinations. QY: Nobutaka Hirokawa
(Science 23 Jan 98) (Science-Week 6 Feb 98)
8. ON HETEROCHRONY AS A DOMINANT MODE OF DEVELOPMENTAL EVOLUTION
In developmental biology, heterochrony is the dissociation during
development of factors influencing shape and size from sexual
maturity. Recent advances in developmental genetics have made
possible new opportunities to test claims of character identity
and developmental individuality. In insects, for example, it has
been shown that the development of body segments and the
determination of segment identity is caused by different sets of
genes. This fact can be used to compare the identity of body
regions across large taxonomic gaps. Although there is no simple
one to one relationship between gene expression and structural
identity, comparison of gene expression patterns can be used to
test claims of character identity within a defined taxonomic
range of species. Blanco et al (3 authors at 2 installations, US
ES) report a study of gene expression in the African clawed toad
(Xenopus laevis), the data supporting the hypothesis that the
proximal tarsal elements of Xenopus laevis are of lower leg
identity rather than ankle/foot identity, and they suggest that a
heterochronic difference in gene expression contributes to a
change in the structural identity of tarsal elements in the hind
limb bud and that this underscores the importance of heterochrony
as a dominant mode of the evolution of development.
QY: Guenter P. Wagner (gpwag@peaplant.biology.yale.edu)
EMAIL
(Devel. Genes and Evolution, in press) (Science-Week 24 Apr 98)
9. FREE CALCIUM LEVEL CHANGES INDUCED BY ELASTIN PEPTIDES
In animals, epithelial cells compose the cell layers that form
the interface between a tissue and the external environment, for
example, the cells of the skin, the lining of the intestinal
tract, and the lung airway passages. In contrast, endothelial
cells are cells that line vessels such as blood vessels,
lymphatic vessels, and the heart. Basement membranes are
amorphous extracellular layers closely applied to the basal
surface of epithelial cells, and laminin is a large multimeric
glycoprotein found in basement membranes and other extracellular
matrices. Elastic fibers in arteries, pulmonary alveolar septa
(lung air-sac partitions), certain ligaments, and skin are
normally subjected to stretching. In vascular walls, elastic
fibers organize into concentric sheets that endow the arteries
with resiliency. The extracellular matrix protein "elastin" is
the major component of elastic fibers present in the arterial
wall. Physiological degradation of elastin fibers, enhanced in
vascular pathologies, leads to the presence of circulating
elastin peptides that have been demonstrated to influence cell
migration and proliferation, and the elastin peptides also induce
vasorelaxation mediated by a subunit of an elastin-laminin
receptor. The "patch clamp" technique is an electrophysiological
micropipette technique for studying ion currents through a small
patch of cell membrane. ... ... Faury et al (5 authors at 2
installations, FR) report a study of circulating elastin peptides
and their effects on endothelial cells, using the techniques of
patch clamp, spectrofluorimetry, and confocal microscopy. The
authors observed that circulating concentrations of elastin
peptides activate low specificity calcium ion channels in human
umbilical venous endothelial cells, with a resultant increase in
cytoplasmic and nuclear free calcium concentrations. The authors
suggest that elastin peptide-induced signal transduction is
mediated by the elastin-laminin receptor via coupling of
cytoskeletal actin microfilaments to membrane channels and to the
cell nucleus. They also suggest that because vascular remodeling
and carcinogenesis are accompanied by extracellular matrix
modifications involving elastin, the elastin peptide processes
described could play a role in the elastin-laminin receptor-
mediated cellular migration, differentiation, and proliferation
in atherogenesis and carcinogenic metastasis.
QY: Ladislas Robert (lrobert1@compuserve.com)
EMAIL
(Proc. Natl. Acad. Sci. US 17 Mar 98 v95:p2967)
(Science-Week 24 Apr 98)
10. EVIDENCE FOR INTACT SYNAPTIC VESICLES IN ENDOCYTOTIC CYCLE
Neurotransmitters are chemical substances released at the
terminals of nerve axons in response to the propagation of an
impulse to the end of that axon. The neurotransmitter substance
diffuses into the synapse, the junction between the presynaptic
nerve ending and the postsynaptic neuron, and at the membrane of
the postsynaptic neuron the transmitter substance interacts with
a receptor. Depending on the type of receptor, the result may be
an excitatory or an inhibitory effect on the postsynaptic nerve
cell. Synaptic vesicles are the packets of neurotransmitter
substance formed in the presynaptic axon terminals, and when
transmitter substances are released, they are released as
packets, the vesicle membrane apparently fusing with the
presynaptic membrane to release the transmitter molecules. After
fusion of synaptic vesicles with the presynaptic membrane and
secretion of the contents of the vesicles into the synaptic cleft
("exocytosis"), the vesicular membrane is retrieved by
endocytosis (internalization) for re-use. ... ... Murthy and
Stevens (Salk Institute, US) used a fluoresent membrane dye with
quantitative fluorescence microscopy to test the classical model
of synaptic vesicle recycling, and they report that the amount of
dye per vesicle taken up by endocytosis equals the amount of dye
a vesicle releases on exocytosis. The authors therefore conclude
that the internalized vesicles do not, as the classical view
proposes, communicate with intermediate endosome-like intra-
cellular compartments during the recycling process. They suggest
their results are compatible with a model of vesicle recycling in
which endocytosis occurs mainly through internalization of
vesicle-size membrane patches that are exposed to the extra-
cellular space and which then remain intact throughout the
vesicle recycling pathway.
QY: Charles F. Stevens (cfs@salk.edu)
EMAIL
(Nature 2 Apr 98) (Science-Week 24 Apr 98)
(continued in Part 3)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
SCIENCE-WEEK - Part 3/3
A Free Weekly Digest of the News of Science
April 24, 1998
Contents of Part 3:
11. Functional Anatomy of Human Music Processing
12. Classical Conditioning and Brain Systems: Role of Awareness
13. Red Cell Viability in Red Cell Aging and Hemolytic Anemia
14. Centrosome Hypertrophy in Human Breast Tumors
15. Risks to the Fetus of Prescription and Over-the-Counter Drugs
----------------------------------------------------------------
11. FUNCTIONAL ANATOMY OF HUMAN MUSIC PROCESSING
The existence of special perceptuo-motor skills in certain
individuals presents many puzzling questions for the cognitive
neurosciences. One such ability whose cerebral substrate remains
essentially unknown is absolute pitch (also called "perfect
pitch"), a relatively rare ability that refers to a long-term
internal representation for the pitch of tones in the musical
scale, typically manifested behaviorally by the ability to
identify by the name of the musical note the pitch of any sound
without reference to another sound, or by the ability to produce
a given musical tone on demand. In contrast, relative pitch,
which is well-developed among most trained musicians, refers to
the ability to make pitch judgments about the relation between
notes, such as within a musical interval. The term "functional
brain imaging" refers to a number of different techniques for
mapping activity in the brain in response to external stimuli or
during sensory, perceptual, or cognitive events. Positron
emission tomography is a technique for producing cross-sectional
images of the body after ingestion and systemic distribution of
safely metabolized positron-emitting agents. The images are
essentially functional or metabolic, since the ingested agents
are metabolized in various tissues. Fluorodeoxyglucose and
H(sub2)O(sup15) are common agents used for cerebral applications,
and in cerebral applications of central importance to the
technique is the fact that changes in the cellular activity of
the brains of normal, awake humans and unanesthetized laboratory
animals are invariably accompanied by changes in local blood flow
and also changes in oxygen consumption. Magnetic resonance
imaging is a technique involving images produced by mobile
protons of a tissue excited by the application of a magnetic
field, and when used in functional cerebral imaging, the basis of
the technique is that it images very small metabolic, blood-flow,
and perfusion-diffusion changes in vivo, in real time, and with
no risk to the subject. ... ... Zatorre et al (5 authors at
McGill University, CA) report a study of the neural basis of
human absolute pitch using both structural and functional brain
imaging techniques (magnetic resonance imaging and positron
emission tomography). Although there were some localization
differences between absolute pitch possessors and control non-
absolute-pitch musicians when responding to musical tones, the
results as a whole bring the authors to suggest that absolute
pitch may not be associated with a unique pattern of cerebral
activity, but rather may depend on the recruitment of a
specialized network involved in the retrieval and manipulation of
verbal-tonal associations.
QY: Robert J. Zatorre (md37@musica.mcgill.ca)
EMAIL
(Proc. Natl. Acad. Sci. US 17 Mar 98 v95:p3172)
(Science-Week 24 Apr 98)
12. CLASSICAL CONDITIONING AND BRAIN SYSTEMS: ROLE OF AWARENESS
The classical delay conditioning paradigm involves presenting the
conditioned stimulus just before the unconditioned stimulus, and
then both stimuli terminating together. Trace conditioning is a
variant of the standard delay conditioning paradigm, involving a
short interval (0.5 to 1 sec.) interposed between the offset of
the conditioned stimulus and the onset of the unconditioned
stimulus. Animals with hippocampal lesions fail to acquire trace
conditioning, but they do acquire delay conditioning. Clark and
Squire (University of California San Diego, US) report a study of
amnesic human patients with damage to the hippocampal formation
and normal human volunteers. Subjects were tested on two versions
of classical delay conditioning and two versions of trace
conditioning, and then assessed for the extent to which they
became aware of the temporal relationship between the conditioned
stimulus and the unconditioned stimulus. Amnesic patients
acquired delay conditioning at a normal rate, but failed to
acquire trace conditioning. For normal volunteers, awareness was
unrelated to successful delay conditioning but was a prerequisite
for successful trace conditioning. The authors suggest trace
conditioning may provide a means for studying awareness in
nonhuman animals in the context of current ideas about multiple
memory systems and the function of the hippocampus.
QY: Larry R. Squire, Dept. of Neurosciences, Univ. of Calif. San
Diego 619-534-3880.
(Science 3 Apr 98) (Science-Week 24 Apr 98)
13. RED CELL VIABILITY IN RED CELL AGING AND HEMOLYTIC ANEMIA
Eukaryotic cells are cells that have membrane-bound organelles
such as a nucleus, and apoptosis is programmed cell death
produced by control mechanisms designed to destroy defective
cells or cells that must be eliminated in tissue development.
Macrophages are amoeba-like white blood cells of the immune
system that are able to surround and digest foreign entities such
as bacteria and protozoa. Phospholipids are asymmetrically
distributed in the membranes of normal eukaryotic cells, with the
inner leaflet of the bilayer that constitutes the cell membrane
containing phosphatidylserine (in addition to other
phospholipids), and phosphatidylserine not normally present in
the outer leaflet. This distribution is stable in normal cells,
but phosphatidylserine becomes exposed on the outer surface of
the cell membrane in abnormal or apoptotic cells, which signals
macrophages to ingest these cells. In this context, it has been
suggested that the removal of red blood cells from the circulat-
ion because of normal aging or in hemolytic anemias might be
triggered by phosphatidylserine exposure on the outer membrane
surface. ... ... Boas et al (3 authors Scripps Research
Institute, US) report a study of human red blood cells from
patients with hemolytic anemia and from normal controls, using a
chemical (fluorescein) method to tag red blood cells with exposed
phosphatidylserine on their surfaces. The authors report that
increased phosphatidylserine exposure occurs during normal red
cell aging, but occurs only in certain types of hemolytic anemia.
The authors suggest that exposure of phosphatidylserine at the
outer membrane surfaces of red cells apparently does not play a
detectable role in most cases of hemolytic anemia, and that the
search for signals that target macrophages to remove red cells in
most forms of hemolytic anemia must continue.
QY: Ernest Beutler (beutler@bolo.scripps.edu)
EMAIL
(Proc. Natl. Acad. Sci. US 17 Mar 98 v95:p3077)
(Science-Week 24 Apr 98)
14. CENTROSOME HYPERTROPHY IN HUMAN BREAST TUMORS
Microtubules are part of the cytoskeleton of biological cells,
the quasi-rigid matrix that among other things determines cell
shape. The microtubules are 25 nanometers in diameter, and
composed of the protein tubulin. They occur in regular arrays in
cilia, flagella, the mitotic spindle, and in the cytoplasm in
general, and they contribute not only to cell shape, but also to
cell motility. The centriole, an organelle in biological cells,
is associated with the assembly and organization of microtubules,
and the centrosome is one of many sites on the periphery of a
centriole from which microtubules radiate in the formation of the
spindle apparatus associated with cell division. The centrosome
plays an important role in the maintenance of cell polarity and
in progression through the cell cycle. An adenocarcinoma is a
malignant neoplasm of epithelial cells in a glandular or gland-
ular-like arrangement. ... ... Lingle et al (5 authors at Mayo
Clinic, US) in a study of 35 high grade human breast tumors,
report that centrosomes of adenocarcinoma cells generally display
abnormal structure, aberrant protein phosphorylation, and
increased microtubule nucleating capacity in comparison to
centrosomes of normal breast epithelial and stromal tissues. The
authors suggest these structural and functional centrosome
defects have important implications for understanding the
mechanisms by which genomic instability and loss of cell polarity
develop in solid tumors.
QY: Jeffrey L. Salisbury (salisbury@mayo.edu)
EMAIL
(Proc. Natl. Acad. Sci. US 17 Mar 98 v95:p2950)
(Science-Week 24 Apr 98)
15. RISKS TO THE FETUS OF PRESCRIPTION AND OVER-THE-COUNTER DRUGS
Koren et al (3 authors at University of Toronto, CA) review the
use and dangers of prescription and over-the-counter drugs during
pregnancy. Teratogenesis is defined as the dysgenesis of fetal
organs as evidenced either structurally or functionally (e.g.,
brain function). The typical manifestations of teratogenesis are
restricted growth or death of the fetus, carcinogenesis, and
malformations. These abnormalities vary in severity, and major
malformations may be life-threatening and require major surgery
or may have serious cosmetic or functional effects. At the
present time, the following drugs have been proven to have
teratogenic effects in humans when used at clinically recommended
doses: aminopterin, methotrexate, angiotensin-converting enzyme
inhibitors, anticholinergic drugs, antithyroid drugs,
carbamazepine, cyclophosphamide, danazol and other androgenic
drugs, diethylstilbestrol, hypoglycemic drugs, lithium,
misoprostol, nonsteroidal anti-inflammatory drugs,
paramethadione, phenytoin, psychoactive drugs (e.g.,
barbiturates, opioids, benzodiazepines), systemic retinoids,
tetracycline, thalidomide, trimethadione, valproic acid,
warfarin. The authors point out that since half the pregnancies
in North America are unplanned, every year hundreds of thousands
of women expose their fetuses to drugs before they know they are
pregnant. The authors suggest that the medical community and drug
manufacturers make a concerted effort to protect women and their
unborn babies from teratogenic risks associated with over-the-
counter and prescription drugs. QY: Gideon Koren, Hospital for
Sick Children, 555 University Avenue, Toronto, ON M5G 1X8 CA.
(New England J. Med. 16 Apr 98) (Science-Week 24 Apr 98)
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BOOK NOTES:
Cold Spring Harbor Laboratory:
PATTERN FORMATION DURING DEVELOPMENT
Cold Spring Harbor, 1998, 570p, US250, paper US105
A CSHL Symposium volume. An authoritative survey of the induction
of axes, control of cell migration, development of the nervous
system, limbs, wings, and other organs. 61 authors. Nearly all
CSHL Symposium volumes become enduring classics, and this will be
no exception.
Benno Mueller-Hill: MURDEROUS SCIENCE
Elimination by Scientific Selection of Jews, Gypsies, and Others
in Germany 1933-1945
Cold Spring Harbor, 1998, 256p, US29
The author is a distinguished German geneticist, and this is an
English translation of his *Toedliche Wissenschaft*. A document-
ation of the collusion of eugenics and racist politics that
resulted in the mass murder of millions. In a new Afterword, the
author warns against the misuse of newly-emerging knowledge of
human heredity. In an accompanying essay, Nobel Laureate James D.
Watson describes a recent visit to Berlin and his impressions of
the legacy of eugenics in German science. This is certainly an
important volume for any library seeking a serious collection on
the subject.
Barry Parker: ALIEN LIFE
The Search for Extraterrestrials and Beyond
Plenum, 1998, 254p, US27.95 CA38.95
A journalistic nontechnical account by a retired astrophysicist,
this can serve the general reader as a useful antidote to the
reams of published nonsense on the subject. Parker leaves the
question of Martian nanofossils unresolved. Contains both an
index and a helpful bibliography of other nontechnical sources.
J.P. Robinson and G. Babcock: PHAGOCYTE FUNCTION
A Guide for Research and Clinical Evaluation
Wiley, 1998, 430p, 89.95
Explores various approaches to measuring phagocyte function in
both research and clinical settings. Flow cytometry, confocal
microscopy, functional abnormalities of phagocytes in patients
with AIDS, cancer, severe burns, neonates, etc.
Matthew F, Schlecht: MOLECULAR MODELING ON THE PC
Wiley, 1998, 784p, US125
A book/disk package. Explanations and techniques involving
current programs, particularly PCMODEL 5.13 and 6.0. Examples and
exercises, references to published computer experiments. The
disk
contains a structure input file library, and an HTML document
listing molecular modeling sites on the Internet.
Ursual E. Spichiger-Keller:
CHEMICAL SENSORS AND BIOSENSORS FOR MEDICAL AND BIOLOGICAL
APPLICATIONS
Wiley, 1998, 426p, US140
A reference for details on using sensors in a wide range of
medical and biological applications. Basic principles and
concepts of sensor technology, choosing or designing sensors for
specific purposes, analytical result interpretation, advantages
of chemical and biosensors over other methods.
Michael White: ISAAC NEWTON
The Last Sorcerer
Addison-Wesley, 1998, 320p, US27
A biography of Newton with some emphasis on Newton's
psychological aspects, explorations in alchemy, biblical
chronology, prophecy, magic, etc. Science-writer White is also
the author of a book about Stephen Hawking.
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