bluuebunny/crossref_metadata_2025 huggingface dataset:
Hindered Diffusion in Microporous Membranes with Known Pore Geometry
Authors: Beck Robert E. , Schultz Jerome S.
Published: October 2006

The hindrance effect on the aqueous diffusion rate of solutes within membrane pores of molecular size has been accurately determined. Mica membranes, 3 to 5 micrometers thick, were prepared with uniform, straight pores from 90 to 600 angstroms in diameter. With these membranes a direct estimation was possible of the interaction between pore size and molecular diffusion rates. There were no uncertainties due to wide pore size distributions or nonuniform tortuous channels as in previously used model microporous materials such as dialysis tubing or gels. Aqueous diffusion rates through these mica membranes were measured for a series of compounds with molecular diameters from 5.2 to 43 angstroms and were corrected for "liquid film resistances" adjacent to the membrane-solution interface to obtain estimates of molecular diffusivities within the micropores of the membrane. Definite evidence is presented showing that, even when molecular size is a small fraction of pore size, diffusion rates decrease markedly. The apparent reduction in solute diffusivity in the microporous membrane can be quantitatively estimated by means of the Renkin equation for hindered diffusion.
Reduced Catechol-
O
-Methyltransferase Activity in Red Blood Cells of Women with Primary Affective Disorder
Authors: Cohn Cal K. , Dunner David L. , Axelrod Julius
Published: October 2006

Red blood cell catechol-
O
-methyltransferase, histamine-
N
-methyltransferase, and a methanol-forming enzyme were examined in a number of subjects with mental diseases. Catechol-
O
-methyltransferase activity was significantly reduced in female subjects with primary affective disorder (depression) as compared to normal women and men, men with primary affective disorder, and schizophrenic men and women. In depressed women, histamine-
N
-methyltransferase activity was elevated and the methanol-forming enzyme was unchanged.
Galaxies and the Universe
Authors: Oort J. H.
Published: October 2006

A brief review is given of what the study of galaxies has taught us about properties of the universe. It is assumed that the universe started from a general "explosion," and that the general expansion observed today, as well as the 3°K blackbody radiation, are consequences of this explosion. The present average density in the universe is probably close to the critical value of 10
-29
g/cm
3
. Only about 3 percent of this is contained in galaxies; the rest consists probably of intergalactic gas at a temperature between 10
5
and 10
6
°K. Observations in our own galaxy indicate that this intergalactic gas is still flowing into it.
Specificity of Antigen Recognition by Human Lymphocytes in vitro
Authors: Zoschke David C. , Bach Fritz H.
Published: October 2006

Delayed hypersensitivity reactions in vivo are exquisitely specific, in terms of both a lack of response after induction of tolerance and a response after sensitization. These studies in vitro demonstrate that this specificity, at least at the level of antigen recognition, is probably derived from different populations of cells, each responding to different antigens.
Tongue Cooling: A New Reward for Thirsty Rodents
Authors: Mendelson Joseph , Chillag Dana
Published: October 2006

Thirsty rodents will persistently lick a stream of dry air pumped through a standard drinking tube. This air-licking is attenuated by experimental manipulations which reduce the evaporative cooling of the tongue and mouth produced by the airstream. This suggests that such cooling is itself an effective reward for thirsty rodents. We tested this hypothesis by presenting thirsty rodents with a piece of cold, dry metal. Different species spent from 9 to 40 percent of their session time licking the cold metal. When deprived of water hamsters reared from birth without access to drinking water licked cold metal in preference to metal maintained at room or body temperature. This preference was approximately equal to that of littermates reared normally. We conclude that tongue cooling is a primary reward for thirsty rodents.
Superior Colliculus: Single Unit Responses to Stimulation of Visual Cortex in the Cat
Authors: McIlwain James T. , Fields Howard L.
Published: October 2006

Electrical stimulation of area 18 of the cat visual cortex produces intense excitation of neurons in the superior colliculus. Excitation is followed by a period of decreased collicular responsiveness to light stimulation. These effects are seen in both directionally selective and nonselective units. The corticocollicular projection is retinotopically organized.
Kinetics of Gramicidin Channel Formation in Lipid Bilayers: Transmembrane Monomer Association
Authors: O'Connell Anne M. , Koeppe Roger E. , Andersen Olaf S.
Published: October 2006

Conducting gramicidin channels form predominantly by the transmembrane association of monomers, one from each side of a lipid bilayer. In single-channel experiments in planar bilayers the two gramicidin analogs, [Val
1
]gramicidin A (gA) and [4,4,4-F
3
-Val
1
]gramicidin A (F
3
gA), form dimeric channels that are structurally equivalent and have characteristically different conductances. When these gramicidins were added asymmetrically, one to each side of a preformed bilayer, the predominant channel type was the hybrid channel, formed between two chemically dissimilar monomers. These channels formed by the association of monomers residing in each half of the membrane. These results also indicate that the hydrophobic gramicidins are surprisingly membrane impermeant, a conclusion that was confirmed in experiments in which gA was added asymmetrically and symmetrically to preformed bilayers.
Ca2
+
Permeability of KA-AMPA—Gated Glutamate Receptor Channels Depends on Subunit Composition
Authors: Hollmann Michael , Hartley Melissa , Heinemann Stephen
Published: October 2006

NMDA (
N
-methyl -D-aspartate) receptors and non-NMDA receptors represent the two major classes of ion channel-linked glutamate receptors. Unlike the NMDA receptor channels, non-NMDA receptor channels have usually been thought to conduct monovalent cations only. Non-NMDA receptor ion channels that can be gated by kainic acid (KA) and α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) are formed by the glutamate receptor subunits GluR1, GluR2, and GluR3. These subunits were expressed in various combinations in
Xenopus
oocytes so that their permeability to divalent cations could be studied. At physiological resting potentials, KA and AMPA elicited inward calcium currents in oocytes expressing GluR1, GluR3, and GluR1 plus GluR3. In contrast, oocytes expressing GluR1 plus GluR2 or GluR3 plus GluR2 showed no such permeability. Thus, in neurons expressing certain KA-AMPA receptor subunits, glutamate may trigger calcium-dependent intracellular events by activating non-NMDA receptors.
Paleotemperature Variations across the Plio-Pleistocene Boundary
Authors: Emiliani Cesare
Published: October 2006

Strong variations in the O
18
/O
16
and C
13
/C
12
ratios occur through the type section for the Plio-Pleistocene boundary, but the boundary itself is not characterized by unusual isotopic gradients.
Pulmonary Compliance: Alteration during Infection
Authors: Somerson Norman L. , Kontras Stella B. , Pollack J. Dennis , Weiss Harold S.
Published: October 2006

Lungs excised from rats infected with
Mycoplasma pulmonis
are more difficult to inflate with air than those from uninfected animals; they show no significant differences from controls inflated with saline. The altered pulmonary function in lungs from infected rats is attributed to an increase in surface forces, implying disruption of the lung surfactant system.
Pinocytosis and Membrane Dilation in Uranyl-Treated Plant Roots
Authors: Wheeler Harry , Hanchey Penelope
Published: October 2006

Electron-dense crystals formed in plant roots exposed to uranyl acetate have been used to identify binding sites and to follow the pinocytotic uptake of uranyl in the oat rootcap. Before uranyl enters the protoplast, the plasmalemma is greatly dilated. After uranyl is sequestered in vacuoles, the tonoplast is similarly dilated.
Scanpaths in Eye Movements during Pattern Perception
Authors: Noton David , Stark Lawrence
Published: October 2006

Subjects learned and recognized patterns which were marginally visible, requiring them to fixate directly each feature to which they wished to attend. Fixed "scanpaths," specific to subject and pattern, appeared in their saccadic eye movements, both intermittently during learning and in initial eye movements during recognition. A proposed theory of pattern perception explains these results.
Parthenogenesis: Does It Occur Spontaneously in Mice?
Authors: Whitten W. K.
Published: October 2006

If parthenogenesis occurred in bisexual organisms, it would produce an excess of females and depress the sex ratio. The phenotypes of female mice, from matings that produce an excess of females, were examined for evidence of the presence of marker genes of paternal origin. All proved to be hybrids of the maternal and paternal strains, thus excluding parthenogenesis as the cause of the low sex ratio.
Electrical Activity of the Hypothalamus: Effects of Intraventricular Catecholamines
Authors: Weiner Richard I. , Blake Charles A. , Rubinstein Lidia , Sawyer Charles H.
Published: October 2006

The injection of epinephrine into the third ventricle of the rat brain causes a biphasic elevation and depression in the integrated multiple-unit electrical activity of the median eminence. Activity in the arcuate nucleus decreases after the injection of the catecholamines. These changes in the integrated multiple-unit electrical activity may be related to the secretion of hormones by the anterior pituitary gland.
Endogenetic Craters Interpreted from Crater Counts on the Inner Wall of Copernicus
Authors: Greeley Ronald , Gault Donald E.
Published: October 2006

Collapse craters formed in terrestrial basalt flows exhibit size-frequency distributions that are similar to distributions for craters located in terraces in the inner wall of the lunar crater Copernicus. These distributions and surface morphology suggest that the interior terraces are basalt lava flows containing collapse craters as well as impact craters.
Chromatid Breakage: Cytosine Arabinoside-Induced Lesions Inhibited by Ultraviolet Irradiation
Authors: Benedict William F. , Karon Myron
Published: October 2006

Exposure to ultraviolet light can reduce the frequency of chromatid breaks induced by cytosine arabinoside in the DNA synthetic and post-DNA synthetic phases of the cell cycle. This effect can be correlated temporally with a decrease in the uptake of tritiated thymidine after ultraviolet treatment, implying that the genesis of such breakage is intimately related to DNA synthesis and that such synthesis is not confined to the DNA synthetic phase.
Neural Pathways Associated with Hypothalamically Elicited Attack Behavior in Cats
Authors: Chi Carl Chungming , Flynn John P.
Published: October 2006

Small electrolytic lesions were made in cats through electrodes, which, when stimulated, elicited either quiet biting attack or affective paw strike attack upon rats. The Nauta method for impregnating degenerating axoplasm was used to reveal that degeneration resulting from lesions at quiet attack sites followed largely along the course of the medial forebrain bundle, while the degeneration after lesions of affective attack sites was concentrated more heavily in the periventricular system.
Receptors: Localization and Specificity of Binding of Serotonin in the Central Nervous System
Authors: Alivisatos Spyridon G. A. , Ungar Frieda , Seth Prahlad K. , Levitt Leroy P. , Geroulis Anthony J. , Meyer Thomas S.
Published: October 2006

Formation of a Schiff base between the ethylamine residue of serotonin and an appropriate carbonyl residue at the receptor site may be among the forces holding serotonin onto the receptor. Reduction of this imine may provide a means of permanently labeling receptors as a preliminary to their isolation.
Vitamin B
12
Authors: Stadtman Thressa C.
Published: October 2006

In spite of the considerable progress made in recent years toward the understanding of the chemistry and biological function of the cobalt-containing B
12
group of compounds, much of the information still is more descriptive than definitive in nature. In general terms, it is known that the free vitamin forms can function as methyl group carriers and that the 5′-deoxyadenosyl or coenzyme forms serve as hydrogen carriers; but the mechanism of these processes is not understood in detail. More systematic studies of the pure chemistry of these complex molecules containing a carbon-cobalt covalent bond are needed before the biochemist can interpret many of his observations on the enzyme-catalyzed reactions. Even in relatively simple solutions it is difficult to ascertain the state of oxidation of several of the vitamin forms, and these problems are compounded when the reactive thiol compounds and complex proteins of the biological systems also are present. For example, both vitamin B
12r
(the Co
2+
form) and corresponding analogs are known to disproportionate in solution to B
12s
(Co
1+
) and B
12a
(Co
3+
) under a variety of mild conditions. This means that in the biological systems it is exceedingly difficult to ascertain the chemical nature of many B
12
intermediates and reaction products. The role of the protein moiety of the various B
12
-linked enzymes in the catalytic processes is little known as is, also, the mode of binding of the B
12
derivative to the protein. These types of questions perhaps can be answered eventually by the crystallographers, whose art is becoming increasingly sophisticated.

Note added after preparation of manuscript.
In contrast to the values given in Table 4 for the molecular weights of the two dissimilar protein moieties of glycerol dehydrase, a recent report, gives a value of 188,000 for the molecular weight of a stable, catalytically inactive complex of 1 mole of hydroxocobalamin and 1 mole of the apoenzyme complex of glycerol dehydrase. The latter is presumed to contain one equivalent of each of the two dissimilar protein subunits. The original estimate of 240,000 as the molecular weight of the unstable sulfhydryl protein moiety was undoubtedly made on partially aggregated material.
Echolocation in Bats: Signal Processing of Echoes for Target Range
Authors: Simmons James A.
Published: October 2006

Echolocating bats
Eptesicus fuscus
and
Phyllostomus hastatus
can discriminate between the nearer and farther of two targets. Their errors in discrimination are predicted accurately by the autocorrelation functions of their sonar cries. These bats behave as though they have an ideal sonar system which cross correlates the transmitted cry with the returning echo to extract target-range information.
Perinatal Undernutrition: Accumulation of Catecholamines in Rat Brain
Authors: Shoemaker William J. , Wurtman Richard J.
Published: October 2006

Brains of rats undernourished from midgestation and killed at weaning contained 25 percent less norepinephrine than brains of adequately fed littermates. Perinatal undernutrition also suppressed the accumulation of brain dopamine. Paradoxically, the activity of tyrosine hydroxylase, the enzyme thought to be rate-limiting in catecholamine biosynthesis, was significantly increased in brains from undernourished animals.
Possible Etiology of Schizophrenia: Progressive Damage to the Noradrenergic Reward System by 6-Hydroxydopamine
Authors: Stein Larry , Wise C. David
Published: October 2006

Single or repeated intraventricular injections of 6-hydroxydopamine caused marked and long-lasting deficits in brain self-stimulation and other rewarded behaviors in the rat. The behavioral deficits, as well as the depletion of brain norepinephrine induced by 6-hydroxydopamine, were prevented by prior treatment with chlorpromazine. Episodic or continuous formation of endogenous 6-hydroxydopamine in man as a result of a genetically determined enzymatic error could selectively damage the binding capacity and, eventually, the structural integrity of the noradrenergic reward mechanism. Such damage might cause the fundamental symptoms and long-term downhill course of schizophrenia.
Late Pleistocene Paleotemperatures at Tongue of the Ocean, Bahamas
Authors: Lynts George W. , Judd James B.
Published: October 2006

Estimates of paleotemperatures, based upon paleoecological analysis of planktonic foraminiferal thanatocoenoses of three piston cores from Tongue of the Ocean, Bahamas, indicate a maximum mean variation between Late Pleistocene glacial and nonglacial stages of 3.6°C. The data also indicate that the Early Wisconsin glacial stage was 0.7°C warmer than the Late Wisconsin glacial stage.
DNA Synthesis in Differentiating Skeletal Muscle Cells: Initiation by Ultraviolet Light
Authors: Stockdale Frank E.
Published: October 2006

As skeletal muscle cells differentiate, they fail to initiate DNA synthesis. This rigid regulation, which persists even after cells are fully developed, does not extend to "repair" DNA synthesis, in that ultraviolet light initiates DNA synthesis in 99 percent of the muscle nuclei exposed. The rate of "repair" DNA synthesis in these nuclei, however, drops over 50 percent at the time of cell differentiation.
Conformational Equilibria in Spin-Labeled Hemoglobin
Authors: Deal Walter J. , Mohlman Susan G. , Sprang Marcia L.
Published: October 2006

A component characteristic of deoxyhemoglobin appears in the paramagnetic resonance spectrum of spin-labeled oxyhemoglobin, and vice versa, under conditions of
p
H and ionic strength consistent with the interpretation that the spectrum is sensitive to the conformational equilibrium of the carboxy-terminal histidines. The oxygenation-induced change in the resonance spectrum is discussed in terms of shifts in this equilibrium.
Synaptic Transmission in the Crayfish: Increased Release of Transmitter Substance by Bacterial Endotoxin
Authors: Parnas I. , Reinhold R. , Fine J.
Published: October 2006

Bacterial endotoxin increases the frequency of miniature excitatory postsynaptic potentials, decreases facilitation, and increases the evoked excitatory postsynaptic potential without changing membrane resistance. These data indicate that endotoxin acts on the presynaptic nerve terminal by increasing the amount of transmitter substance released in response to an applied stimulus.
Alpha and Kappa Electroencephalogram Activity in Eyeless Subjects
Authors: Chapman Robert M. , Cavonius C. R. , Ernest J. Terry
Published: October 2006

Several reports have cast doubt on the cerebral origin of alpha and kappa electroencephalogram activity by charging that they are artifacts related to eye activity. Data are cited which eliminate the corneoretinal potential of the eyeball, tremor of the extraocular muscles, eye position, accommodation, and eye flutter as sources of alpha and kappa electroencephalogram activity. A subject with both eyes removed showed normal alpha and kappa electroencephalogram activity. Marked left-right differences in alpha activity were not found in one-eyed subjects whose eyes and extraocular muscles were completely removed on one side.
Lunar and Terrestrial Ilmenite Basalt
Authors: Goldich S. S.
Published: October 2006

A basalt hornfels from the Keweenawan Duluth complex in Minnesota contains 7 percent by weight of titanium dioxide and is similar in many respects to the Apollo 11 samples. Hornfels texture, as well as primary textures in lunar rocks, resemble those in Keweenawan rocks.
Taste Stimuli: Quality Coding Time
Authors: Halpern Bruce P. , Tapper Daniel N.
Published: October 2006

Rats conditioned to avoid drinking 300 millimolar NaCl recognized and rejected this solution within 250 to 600 milliseconds of onset of stimulus, a period containing the phasic portion of the peripheral neural response. They generalized to 500 millimolar NaCl but not to 500 millimolar sucrose. Rejection was based on quality identification neurally encoded within this brief period.
Transmitter Release During Repetitive Stimulation: Selective Changes Produced by Sr
2+
and Ba
2+
Authors: Zengel Janet E. , Magleby Karl L.
Published: October 2006

The addition of Sr
2+
or Ba
2+
to the solution bathing the frog neuromuscular junction leads to an increased release of transmitter by each nerve impulse during and following repetitive stimulation. The mechanisms by which Sr
2+
and Ba
2+
increase release are not the same. Each ion appears to act selectively on a different process involved in transmitter release.
In Vitro Demonstration of an Endothelial Proliferative Factor Produced by Neural Cell Lines
Authors: Suddith R. L. , Kelly P. J. , Hutchison H. T. , Murray E. A. , Haber B.
Published: October 2006

Cultured endothelial cells exhibit a six- to tenfold increase in thymidine labeling index in response to a soluble factor elaborated by clonal cell lines of neural origin. This factor, endothelial proliferation factor, appears to be a unique property of tumor cells and may mediate the vascularization of these neoplasms.
Cyclic AMP-Dependent Protein Kinase: Pivotal Role in Regulation of Enzyme Induction and Growth
Authors: Insel Paul A. , Bourne Henry R. , Coffino Philip , Tomkins Gordon M.
Published: October 2006

Dibutyryl cyclic adenosine 3′,5′-monophosphate (cyclic AMP) produces phosphodiesterase induction, growth arrest, and cytolysis in S49 lymphoma cells. The striking parallelism between protein kinase activity that is dependent on cytosol cyclic AMP and cellular responses to dibutyryl cyclic AMP in wild-type cells and three classes of clones resistant to cyclic AMP indicates that protein kinase mediates cyclic AMP regulation of growth and enzyme induction in S49 cells.
Suppression of the Immune Response by a Soluble Complement Receptor of B Lymphocytes
Authors: Hebell Thomas , Ahearn Joseph M. , Fearon Douglas T.
Published: October 2006

The CD19-CR2 complex of B lymphocytes contains proteins that participate in two host-defense systems, the immune and complement systems. The ligand for the subunit of the immune system, CD19, is not known, but the complement receptor subunit, CR2 (CD21), binds activation fragments of the C3 component of the complement system and may mediate immunopotentiating effects of complement. A recombinant, soluble CR2 was prepared by fusing the C3-binding region of the receptor to immunoglobulin G1 (IgG1). The (CR2)
2
-IgG1 chimera competed with cellular CR2 for C3 binding and suppressed the antibody response to a T cell-dependent antigen when administered to mice at the time of immunization. This inhibitory effect of (CR2)
2
-IgG1 demonstrates the B cell-activating function of the CD19-CR2 complex and suggests a new method for humoral immunosuppression.
A Bacterial System for Investigating Transport Effects of Cystic Fibrosis—Associated Mutations
Authors: Gibson Amy L. , Wagner Lois M. , Collins Francis S. , Oxender Dale L.
Published: October 2006

LIV-I, a high-affinity system that transports neutral, branched-chain amino acids into
Escherichia coli
, has two components, LivG and LivF, that are homologous to the cystic fibrosis (CF) transmembrane conductance regulator (CFTR). CF-associated mutations of human CFTR were introduced into corresponding regions of LivG, and their effects on leucine transport could be grouped into three classes. Mutations were found that (i) abolished LIV-I-directed transport, (ii) retained about a quarter of wild-type activity at the Michaelis-Menten constant (
K
M
), and (iii) had minimal activity at the
K
M
. A mutation equivalent to a benign polymorphism had no effect on transport. The correlation of these mutational phenotypes in LivG and CFTR suggests that the LIV-I prokaryotic transporter is functionally similar to the CF protein and that this similarity can be exploited to clarify the properties of the nucleotide-binding fold in this superfamily of proteins.
Mission-Oriented R & D
Authors: Nichols Rodney W.
Published: October 2006

Mansfield's Section 203 has triggered a searching review by DOD of its research. Using the general budget constraints of the past few years as an effective springboard, Mansfield went on to question and then challenge all of the federal government's policies for R & D. The entire post-World War II institutional machinery and rhetoric for R & D are now in some disarray and, thus, are open to imaginative, constructive change. Mission-oriented R & D, still central to progress toward our national goals, must be comprehensively rethought in order to restore the public confidence necessary for adequate support of science and technology.
Activity of Δ
8
- and Δ
9
-Tetrahydrocannabinol and Related Compounds in the Mouse
Authors: Christensen H. D. , Freudenthal R. I. , Gidley J. T. , Rosenfeld R. , Boegli G. , Testino L. , Brine D. R. , Pitt C. G. , Wall M. E.
Published: October 2006

The 11-hydroxy metabolites of Δ
8
- and Δ
9
-tetrahydrocannabinol are more active than the parent compounds when administered to mice by either the intravenous or intracerebral route. Both Δ
8
- and Δ
9
-tetrahydrocannabinol are rapidly and extensively metabolized by the liver and not by the brain. The hypothesis that the 11-hydroxy metabolites may be the active form of tetrahydrocannabinol is discussed.
Microsomal Hydroxylase Induction in Liver Cell Culture by Phenobarbital, Polycyclic Hydrocarbons, and
p
,
p
′-DDT
Authors: Gielen J. E. , Nebert D. W.
Published: October 2006

Aryl hydrocarbon hydroxylase induction by phenobarbital, polycyclic hydrocarbons, and the insecticide, 2.2-bis(p-chlorophenyl)-1,1,1-trichloroethane (
p
,
p
′-DDT), occurs in rat fetal liver cell cultures. The maximum net rate at which the hydroxylase activity accumulates is about the same when phenobarbital, 3-methylcholanthrene, or benz[
a
]anthracene is in the growth medium at optimum concentrations. An additive effect is obtained when either phenobarbital or
p
,
p
′-DDT is present with a polycyclic hydrocarbon in the growth medium, but not when the cells are treated with phenobarbital plus
p
,
p
′-DDT or with the combination of two polycyclic hydrocarbons.
Whole Body Response of the Moon to Electromagnetic Induction by the Solar Wind
Authors: Sonett C. P. , Dyal P. , Parkin C. W. , Colburn D. S. , Mihalov J. D. , Smith B. F.
Published: October 2006

A comparison has been made of the interplanetary magnetic field as measured both by Apollo 12 on the lunar surface and by Explorer 35 in orbit around the moon. Two examples are given, one of a step change in the field vector and another of a sinusoidally varying field. A large response measured on the surface is attributed to confinement of the induced field lines between the streaming solar plasma and the high-conductivity interior. A steep bulk electrical conductivity gradient in the lunar crust is implied, with a confining layer roughly 100 kilometers deep.
Soft X-Rays from the Cygnus Loop: Interpretation
Authors: Tucker Wallace H.
Published: October 2006

Two possible interpretations of the recent soft x-ray observation of the Cygnus Loop are discussed. A synchrotron model requires a magnetic field less than 10
-6
gauss and electron energies in excess of 10
14
electron volts. These electrons must either have been reaccelerated or continuously injected into the source for about 50,000 years. The observations are also consistent with the radiation from a hot plasma having the cosmic abundances of the elements. A likely origin for the hot plasma is a blast wave produced by the explosion of a supernova in the interstellar medium. Fitting such a model to the observations implies a kinetic energy release in the explosion of 6 × 10
50
ergs, for an assumed distance of 770 parsec.
Striated Muscle Fibers: Facilitation of Contraction at Short Lengths by Caffeine
Authors: Rüdel Reinhardt , Taylor Stuart R.
Published: October 2006

One of the factors evidently responsible for decreasing the force of muscle contraction with shortening is inactivation of the myofibrils in the core of a muscle fiber. Caffeine antagonizes this inactivation and, correspondingly, changes the length-force relationship at short muscle lengths.
Summating Potential with Electrical Stimulation of Crossed Olivocochlear Bundles
Authors: Konishi T. , Slepian J.
Published: October 2006

Electrical stimulation of crossed olivocochlear bundles resulted in increase of the positive summating potential in response to high-frequency tone bursts when the summating potential was recorded in the basal turn of the cochlea in anesthetized and immobilized guinea pigs. Strychnine locally applied suppressed the changes of the summating potential.
Renin Secretion: An Anatomical Basis for Tubular Control
Authors: Barajas Luciano
Published: October 2006

By means of electron microscopy of serial sections and three-dimensional reconstruction of the juxtaglomerular apparatus a quantitative study has been made of the distribution of the areas of contact between the tubular and vascular components. Of the two arterioles the efferent is the only one consistently in contact with the distal tubule. The extraglomerular mesangium is also in contact with the distal tubule in all the apparatuses examined. Two morphologically distinct types of contact are described; one is thought to be permanent and the other reversible. An analysis of the cells of the juxtaglomerular apparatus for their position, granularity, and contact has revealed that the majority of granular cells are not in contact with the distal tubule. The anatomical findings are integrated in a model of the control of renin secretion based on variations in contact between the elements of the juxtaglomerular apparatus.
Unique Type of Angiosperm Pollen from the Family Annonaceae
Authors: Walker James W.
Published: October 2006

The primitive angiosperm family Annonaceae possesses a remarkable type of pollen that appears unique in its size (diameter up to 350 micrometers), lack of exine over nearly 50 percent of the grain surface at maturity, and proximalipolar aperture. This unique pollen is further distinguished by being in polyads which are compartmentalized individually within septate stamens.
Preavoidance Blood Pressure Elevations Accompanied by Heart Rate Decreases in the Dog
Authors: Anderson David E. , Brady Joseph V.
Published: October 2006

Blood pressure and heart rate were monitored continuously in five dogs for 1 hour before performance on a free-operant shock-avoidance task. Cardiovascular changes during the preavoidance hour were characterized by sustained and significant increases in blood pressure, and sustained and significant decreases in heart rate.
Computer Graphics as an Aid to Learning
Authors: Hammond Kenneth R.
Published: October 2006

Departing from the traditional model for teaching and learning, this article deals with the problem of teaching and learning the effective application of knowledge already acquired. To this end, a model for the process of exercising judgment was outlined, and the results of an empirical study of judgmental learning were employed to show the inadequacy of the traditional outcome feedback procedures. Computer graphics techniques were used to provide new forms of information to the learner; the results are promising for the rapid learning of a task that would otherwise be difficult to learn.
One-Trial Learning and Biphasic Time Course of Performance in the Goldfish
Authors: Riege Walter H. , Cherkin Arthur
Published: October 2006

Goldfish (
N
= 408) spontaneously swam against flowing water into a calm-water well. After a single trial punished by brief electric shock, the fish avoided the well, as indexed by increased latencies of reentry. Avoidance declined during the first minute after shock, then rose to a peak 1 hour later. The biphasic time course is compatible with the two-store theory of memory formation.
On-Transient of Insect Electroretinogram: Its Cellular Origin
Authors: Alawi Adnan A. , Pak William L.
Published: October 2006

Electrical responses to light stimuli were recorded intracellularly from the retinula cells and the laminar cells of the wild type and the x-7 mutant of
Drosophila melanogaster
in order to determine the cellular origin of the on-transient of the insect electroretinogram. The response of the retinula cell of the mutant x-7 closely resembles that of the wild type even though the on-transient is absent from the electroretinogram of x-7. Neither contains a spike-like component that can be identified with the on-transient of the electroretinogram. However, a spike-like response resembling the on-transient in latency and time course has been obtained from one of the several types of cells in the lamina of the wild type. Moreover, the same response could not be obtained from the laminar cells of the mutant x-7. Thus, the on-transient does not appear to originate from the retinula cell but probably from one or more of several types of cells in the lamina.
Salt Extraction of Soluble HL-A Antigens
Authors: Reisfeld R. A. , Pellegrino M. A. , Kahan B. D.
Published: October 2006

Extraction of cultured human lymphoid cells with hypertonic salt solutions (3 molar potassium chloride) resulted in high recoveries of membrane-associated histocompatibility (HL-A) antigens in soluble form with potent activity and marked immunologic specificity. The active principle was purified by preparative acrylamide-gel electrophoresis. Application of the hypertonic salt extraction method is now yielding sufficient HL-A antigen to begin the elucidation of the molecular basis of transplantation individuality.
Inhibition of Biogenic Amine Uptake by Hydrogen Peroxide: A Mechanism for Toxic Effects of 6-Hydroxydopamine
Authors: Heikkila Richard , Cohen Gerald
Published: October 2006

Hydrogen peroxide, dialuric acid, or 6-hydroxydopamine inhibited the uptake of dopamine, norepinephrine, and serotonin into rat brain synaptosomal preparations. The addition of catalase protected all systems, but catalase was only partially protective for 6-hydroxydopamine acting upon catecholamine uptake. The data show that 6-hydroxydopamine generates hydrogen peroxide and that hydrogen peroxide can damage the biogenic amine uptake systems. Part of the damage caused by the 6-hydroxydopamine that accumulates in the catecholamine nerve terminals in vivo may be attributed to the hydrogen peroxide.
Immunocompetent Cells among Mouse Thymocytes: A Minor Population
Authors: Leckband E. , Boyse E. A.
Published: October 2006

Suspensions prepared from thymuses of TL
+
mice contain a majority of TL
+
cells and a minority of TL
-
cells. The graft versus host reactivity of the TL
-
population is much greater than that of the whole population, as judged by the numbers of cells required to give splenic enlargements in Simonsen's assay. It is proposed that the TL
-
thymocyte represents a stage in the differentiation of TL
+
thymocytes into immunocompetent lymphocytes.
Phenylmercuric Acetate: Metabolic Conversion by Microorganisms
Authors: Matsumura Fumio , Gotoh Yoshiko , Boush G. Mallory
Published: October 2006

Phenylmercuric acetate, an organomercurial that has been widely used as a fungicide and slimicide, was found to be metabolized quickly by soil and aquatic microorganisms. One of the major metabolic products was identified to be diphenylmercury. In none of the cases has a methylmercury derivative been found among the microbial metabolic products of phenylmercuric acetate.
Quantitative Aspects of Plasma Membrane-Associated Immunoglobulin in Clones of Diploid Human Lymphocytes
Authors: Lerner Richard A. , McConahey Patricia J. , Dixon Frank J.
Published: October 2006

The amount of κ and λ chains and Fc fragment associated with the plasma membrane and in the entire cell has been measured for eight lines of human lymphocytes and 21 clones derived from two diploid lines. There was considerable variation in the nature and amount of membrane-associated immunoglobulin and total immunoglobulin among different cell lines and clones. Cells with different phenotypes for membrane-associated immunoglobulin were utilized to show that it is not simply absorbed from the culture medium onto the plasma membrane. The methods are useful for selecting variants which lack or have altered membrane-associated immunoglobulin.
Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate
Authors: Rasool S. I. , Schneider S. H.
Published: October 2006

Effects on the global temperature of large increases in carbon dioxide and aerosol densities in the atmosphere of Earth have been computed. It is found that, although the addition of carbon dioxide in the atmosphere does increase the surface temperature, the rate of temperature increase diminishes with increasing carbon dioxide in the atmosphere. For aerosols, however, the net effect of increase in density is to reduce the surface temperature of Earth. Because of the exponential dependence of the backscattering, the rate of temperature decrease is augmented with increasing aerosol content. An increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5°K. If sustained over a period of several years, such a temperature decrease over the whole globe is believed to be sufficient to trigger an ice age.
Informal Contacts in Science: A Probabilistic Model for Communication Processes
Authors: Griffith Belver C. , Jahn Marilyn J. , Miller A. James
Published: October 2006

Significant contacts among scientists within research specialties are generally infrequent and are distributed as an essentially random process, the pattern of most contacts conforming to a Poisson distribution. Extremely productive persons in a specialty, however, seem to form a separate distribution; they have a considerably higher number of contacts.
Hybrid Ribosome Formation from
Escherichia coli
and Chloroplast Ribosome Subunits
Authors: Lee Sung Gue , Evans William R.
Published: October 2006

A 70
S
ribosome was prepared from a 30
S
ribosome subunit from
Euglena gracilis
chloroplasts and a 50
S
ribosome subunit from
Escherichia coli
. This hybrid ribosome was active in polyuridylic acid-directed polyphenylalanine synthesis.
Euglena gracilis
: Formation of Giant Mitochondria
Authors: Calvayrac Regis , Van Lente Fred , Butow Ronald A.
Published: October 2006

The addition of antimycin A (0.5 microgram per milliliter) to cultures of a bleached strain of
Euglena gracilis
in the logarithmic phase of growth on succinate as a carbon source results in (i) an interruption of growth for 24 hours and (ii) an increase in whole-cell respiration and the emergence of a novel succinoxidase activity within 2 to 4 hours. After 3 to 5 hours, the mitochondria enlarge, fuse, and form a sheathlike structure situated close to the periphery of the cell.
Genetic Aspects of Increase in Rat Liver Aldehyde Dehydrogenase Induced by Phenobarbital
Authors: Deitrich Richard A.
Published: October 2006

In the supernatant fraction of homogenized rat liver, the activity of aldehyde dehydrogenase that is dependent on nicotinamide adenine dinucleotide (E.C. 1.2.1.3) is increased up to tenfold after administration of phenobarbital for 3 days. The effect is genetically controlled and is inherited as an autosomal dominant characteristic. The mechanism is apparently unrelated to other drug-induced increases in enzyme activity such as that which occurs in the hepatic microsomal systems for drug metabolism.
Recovery of Function after Serial Ablation of Prefrontal Cortex in the Rhesus Monkey
Authors: Rosen Jeffrey , Stein Donald , Butters Nelson
Published: October 2006

Rhesus monkeys with one-stage or serial ablation of sulcus principalis (prefrontal association cortex) were compared on three spatial tasks. On all tests, the serial monkeys made fewer errors than did the monkeys with one-stage lesions. These results indicate that partial recovery of function can occur after extensive destruction of association cortex in the mature primate brain if the damage is distributed over a number of operations.
Long-Wavelength Ultraviolet Photoproduction of Amino Acids on the Primitive Earth
Authors: Sagan Carl , Khare Bishun N.
Published: October 2006

Amino acids are produced under possible primitive Earth conditions by irradiation of gas mixtures with long-wavelength ultraviolet light, representing the most abundant useful energy source for prebiological organic synthesis. Hydrogen sulfide is the initial photon acceptor in this work; superthermal atomic hydrogen photodissociation products appear to initiate reactions leading to amino acid synthesis with an overall quantum yield on the order of 5 × 10
-5
Reduction of Stratospheric Ozone by Nitrogen Oxide Catalysts from Supersonic Transport Exhaust
Authors: Johnston Harold
Published: October 2006

Although a great deal of attention has been given to the role of water vapor from supersonic transport (SST) exhaust in the stratosphere, oxides of nitrogen from SST exhaust pose a much greater threat to the ozone shield than does an increase in water. The projected increase in stratospheric oxides of nitrogen could reduce the ozone shield by about a factor of 2, thus permitting the harsh radiation below 300 nanometers to permeate the lower atmosphere.
Gulf Stream and Middle Atlantic Bight: Complex Thermal Structure as Seen from an Environmental Satellite
Authors: Rao P. K. , Strong A. E. , Koffler R.
Published: October 2006

High-resolution infrared imagery from the ITOS 1 satellite demonstrates the utility of synoptic sea-surface temperature information. The northern edge of the Gulf Stream, the slope waters, and the shelf waters display complex thermal characteristics with distinct temperature gradients separating these three water masses. This type of information can be very useful for increasing our understanding of many physical phenomena that occur over Earth's oceans.
Contraction of Granulation Tissue in vitro: Similarity to Smooth Muscle
Authors: Majno G. , Gabbiani G. , Hirschel B. J. , Ryan G. B. , Statkov P. R.
Published: October 2006

Strips of granulation tissue from three different experimental models contract in vitro when treated with substances that induce contraction of smooth muscle. Because the fibroblasts in such tissues have some ultrastructural features typical of smooth muscle, our findings indicate that fibroblasts are able to modulate toward a cell type that is morphologically and functionally close to smooth muscle.
Transplanted Precursors of Nerve Cells: Their Fate in the Cerebellums of Young Rats
Authors: Das Gopal D. , Altman Joseph
Published: October 2006

The multiplying cells of the external granular layer in 7-day-old rats were labeled with [
3
H]thymidine. Slabs of the cerebellum were transplanted into the same region of uninjected hosts of the same age. The transplanted, undifferentiated cells of the donors migrated actively in the cerebellar cortex of the hosts and apparently differentiated there into basket and granule cells.
Defense of Phalangid: Liquid Repellent Administered by Leg Dabbing
Authors: Eisner T. , Kluge A. F. , Carrel J. E. , Meinwald J.
Published: October 2006

The phalangid
Vonones sayi
has a pair of exocrine defensive glands that secrete quinones (2,3-dimethyl-1,4-benzoquinone and 2,3,5-trimethyl-1,4-benzoquinone). When distributed, the animal emits the secretion, dilutes it with aqueous regurgitated fluid, and effects dosaged delivery of the mixture by brushing it on the assailant with the tips of its forelegs. Predators such as ants are effectively repelled.
Cell Dissociation: Univalent Antibodies as a Possible Alternative to Proteolytic Enzymes
Authors: Beug H. , Gerisch G. , Müller E.
Published: October 2006

Univalent antibody fragments directed against special membrane antigens dissociate multicellular bodies of the cellular slime mold
Dictyostelium discoideum
completely into single cells. This provides a gentle method for cell dissociation and demonstrates that a nonenzyme protein can disintegrate a tissue by binding to specific cell surface sites.
Identification of Each Human Chromosome with a Modified Giemsa Stain
Authors: Patil Shivanand R. , Merrick Suzanne , Lubs Herbert A.
Published: October 2006

Differential staining of human chromosomes can be obtained when the
p
H of Giemsa stain is changed to 9.0 from the usual 6.8. Such staining permits identification of all homolog pairs and distinct regions within chromosome arms. In most instances, the pattern is quite similar to that obtained with quinacrine mustard fluorescence staining. Certain regions, such as the paracentric constrictions in chromosomes A1 and C9, and the distal end of the long arm of the Y chromosome stain differently with the Giemsa 9 technique. The technique is considerably simpler than the quinacrine mustard fluorescence technique and identification of homologs is also easier than in cells stained by the latter.
Orbitolina
, a Cretaceous Larger Foraminifer, from Flemish Cap: Paleoceanographic Implications
Authors: Sen Gupta Barun K. , Grant A. C.
Published: October 2006

The Tethyan larger foraminiferal genus
Orbitolina
has been found in the easternmost part of the western North Atlantic continental shelf at 46°30′N. All other known occurrences of the genus in North America are south of 33°N. The species is
Orbitolina conoidea
Gras; its abundance in a grain-supported limestone indicates a tropical neritic environment and precludes the influence of Arctic waters in the Flemish Cap region in Early or Middle Cretaceous times.
Vitamin A: Concentration in the Rat Liver Golgi Apparatus
Authors: Nyquist S. E. , Crane F. L. , Morré D. James
Published: October 2006

Vitamin A compounds (principally as retinyl esters) are concentrated in Golgi apparatus fractions from rat liver. The amounts vary with the vitamin A status of the liver and show an inverse relation to the concentration of ubiquinone. The results suggest a specific role of the Golgi apparatus in the mobilization or action, or both, of vitamin A compounds.
Auditory Evoked Potentials during Speech Perception
Authors: Wood Charles C. , Goff William R. , Day Ruth S.
Published: October 2006

Neural responses evoked by the same binaural speech signal were recorded from ten right-handed subjects during two auditory identification tasks. One task required analysis of acoustic parameters important for making a linguistic distinction, while the other task required analysis of an acoustic parameter which provides no linguistic information at the phoneme level. In the time interval between stimulus onset and the subjects' identification responses, evoked potentials from the two tasks were significantly different over the left hemisphere but identical over the right hemisphere. These results indicate that different neural events occur in the left hemisphere during analysis of linguistic versus nonlinguistic parameters of the same acoustic signal.
Circadian Periodicity in
Neurospora
: Alteration by Inhibitors of Cyclic AMP Phosphodiesterase
Authors: Feldman Jerry F.
Published: October 2006

Three methyl xanthine inhibitors of adenosine 3′,5′-monophosphate phosphodiesterase-theophylline, aminophylline, and caffeine-lengthen the period of the circadian conidiation rhythm of Neurospora. The effects are seen in wild-type strains and in three mutant strains with genetically altered period lengths. These results suggest the possible involvement of adenosine 3′,5′-monophosphate in the control of circadian rhythmicity.
Cyclic Guanosine Monophosphate and Cellular Growth
Authors: Miller Z. , Lovelace E. , Gallo M. , Pastan I.
Published: October 2006

The addition of serum to nongrowing cells decreases cyclic guanosine monophosphate and cyclic adenosine monophosphate levels and promotes cell growth.