bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxoplasma gondii
: Transmission through Feces in Absence of
Toxocara cati
Eggs
Authors: Sheffield Harley G. , Melton Marjorie L.
Published: October 2006

When incubated at room temperature (23°C) for 3 to 14 days, feces from cats infected 4 to 8 days with
Toxoplasma gondii
, and free of
Toxocara cati
eggs, produced toxoplasmosis in mice. Results indicate that the nematode egg is not necessary for transmission of the parasite.
Sex Differences in Verbal and Performance IQ's of Children Undergoing Open-Heart Surgery
Authors: Honzik Marjorie P. , Collart Donna S. , Robinson Saul J. , Finley Knox H.
Published: October 2006

Boys with congenital heart defects had essentially normal Verbal and Performance IQ's on preoperative and postoperative tests; but girls' Verbal IQ's were significantly lower than those of boys, and significantly lower than girls' own Performance IQ's. This sex difference among congenital heart cases reverses the usual finding that girls excel on Verbal tests.
Silicate Spherules from Tunguska Impact Area: Electron Microprobe Analysis
Authors: Glass Billy P.
Published: October 2006

The major oxide composition of four silicate spherules from the area of forest devastated by the explosion of the Tunguska meteorite has been determined by electron microprobe analysis. In general, the spherules have compositions similar to that of igneous glass except for the low iron and the high calcium oxide content of the three spherules that have a low content of silicon dioxide. None of the spherules seem to have compositions similar to the silicate portion of any major meteorite group.
Glucagon-Sensitive Adenyl Cyclase in Plasma Membrane of Hepatic Parenchymal Cells
Authors: Pohl Stephen L. , Birnbaumer Lutz , Rodbell Martin
Published: October 2006

The plasma membrane of hepatic parenchymal cells contains an adenyl cyclase system that is stimulated by glucagon. Adrenocorticotropin and epinephrine do not stimulate this adenyl cyclase, and very little cyclic phosphodiesterase activity is present in the membrane. These findings support the concept that glucagon exerts its regulatory action in the liver by stimulating adenyl cyclase activity in the plasma membrane.
Translocation in Perennial Monocotyledons
Authors: Heyser Wolfgang , Eschrich Walter , Evert Ray F.
Published: October 2006

Gross autoradiography, historadiography, and electron microscopy provide evidence that enucleate sieve elements in basal internodes of relatively old
Tradescantia
plants are still functional.
Lysergic Acid Diethylamide: Effects on the Developing Mouse Lens
Authors: Hanaway J. K.
Published: October 2006

High doses (5 × 10-
6
gram) of LSD-25 given to Swiss-Webster females on gestation days 6, 7, 8, or 9 caused a high incidence of anterior subcapsular lens abnormalities. Accompanying this, the lens epithelium was often hyperplastic, and the lens bow was widened posteriorly in a fashion similar to cataracts induced by x-radiation. Confirmation of this effect of LSD-25 was obtained by a (duplicate) experiment 1 year after the observations reported.
Elements 112 to 119: Were They Present in Meteorites?
Authors: Anders Edward , Heymann Dieter
Published: October 2006

Chondrites contain a small fission xenon component of unexplained origin. Evidence on the geochemical behavior of this component suggests that it was not derived from an actinide element (
Z
= 89 to 103), or from a transition metal between
Z
= 104 and 111, but from a more volatile progenitor. The most likely candidates are the superheavy elements between
Z
= 112 and 119, whose lighter congeners (mercury, tellurium, lead, and the like) are known to be strongly fractionated in meteorites.
Scanning Electron Microscopy of Cells
Authors: Stroud Agnes N. , Welter Leonard M. , Resh Dorothy A. , Habeck Duane A. , Crewe A. V. , Wall J.
Published: October 2006

The scanning electron energy-analyzing microscope uses characteristic energy losses to provide picture contrast. At different levels of energy loss particular structures are distinguished with high contrast in an unstained section of a cell.
Cyclic and Geographic Trends in Seawater Temperature and Abundance of American Lobster
Authors: Dow Robert L.
Published: October 2006

In Maine, fluctuations in the abundance of American lobster (
Homarus americanus
) and in seawater temperature have correlated well during the years since the first temperature measurements were made in 1905. Recent record catches in chronological sequence from the northern limit of range in Newfoundland to New York, while temperatures measured in Maine declined from higher to lower than optimum, suggest that at the present rate optimum conditions should reach the southern limit of the lobster's range by the mid-1970's.
Basic Ferric Phosphates: A Crystallochemical Principle
Authors: Moore Paul B.
Published: October 2006

A polyatomic complex of iron-oxygen octahedral face-sharing triplets corner-linked to four other octahedra occurs in the atomic arrangements of the basic iron phosphates dufrenite, rockbridgeite, beraunite, and laubmannite. This complex is further knit together by the phosphate tetrahedra. The family of basic ferric phosphates arises from the variety of ways in which the complexes can be linked along a third "variable" crystallographic axis.
Inv(1) Allotype: Effect of Immunoglobulin G Heavy Chain Subtype on Its Expression
Authors: Steinberg Arthur G. , Rostenberg Israel
Published: October 2006

More protein is required to detect the Inv(1) antigen carried in the light chain of immunoglobulin G molecules when the light chain is combined with a γ2 heavy chain than when it is combined with a γ1 or γ3 heavy chain. One of the four γ2 heavy chains used in the experiment, however, was as efficient as the γ1 and γ3 chains, indicating that there may be two subtypes of γ2. Inv(1) was more easily detected in one of the two light chains used in the experiment. This difference may be associated with the subtypes of the kappa chain derived from studies of the variable portion of the chain.
Dihydroorotic Acid Dehydrogenase: Introduction into Erythrocyte by the Malaria Parasite
Authors: Krooth Robert S. , Wuu Kuang-dong , Ma Raymond
Published: October 2006

Mature, circulating mammalian erythrocytes lack dihydroorotic acid dehydrogenase activity. However, we have detected activity, which appears to reside in an enzyme, in malaria parasites purified from mammalian blood.
Postsynaptic Membrane Response Predicted from Presynaptic Input Pattern in Lobster Cardiac Ganglion
Authors: Hartline Daniel K. , Cooke Ian M.
Published: October 2006

Given the pattern of impulses impinging on a neuron, it should be possible to predict its output firing pattern if enough is known about pre- and postsynaptic properties. A quantitative reproduction of the first part of this input-output conversion is reported, namely the translation of input pattern into a sequence of postsynaptic membrane potential variations.
Photochemical Decomposition of DDT by a Free-Radical Mechanism
Authors: Mosier A. R. , Guenzi W. D. , Miller L. L.
Published: October 2006

Both as a pure solid and in hexane solution, DDT readily decomposed when irradiated with ultraviolet light (2537 angstroms). Principal products identified by gas-liquid and thin-layer chromatography from irradiations of the solid phase were 1,1-dichloro-2,2-bis (
p
-chlorophenyl) ethane, 1,1-dichloro-2,2-bis(
p
-chlorophenyl) ethylene, and 4,4′-dichlorobenzophenone. 1,1-Dichloro-2,2-bis(
p
-chlorophenyl) ethane and hydrochloric acid were identified from irradiated solutions of DDT in hexane. On the basis of products obtained, quantum yields, scavenger experiments, and other chemical tests, a nonchain, free-radical mode of degradation is proposed.
Vocal Tract Limitations on the Vowel Repertoires of Rhesus Monkey and other Nonhuman Primates
Authors: Lieberman Philip H. , Klatt Dennis H. , Wilson William H.
Published: October 2006

The vowel repertoire of a rhesus monkey (
Macaca mulatta
) was explored by means of a computer program that calculated formant frequencies from the area function of the animal's supralaryngeal vocal tract, which was systematically varied within the limits imposed by anatomical constraints. The resulting vowels were compared with those of humans and with recorded vocalizations of nonhuman primates. The computer model indicates that the acoustic "vowel space" of a rhesus monkey is quite restricted compared to that of the human. This limitation results from the lack of a pharyngeal region that can change its cross-sectional area. These animals thus lack the output mechanism necessary for production of human speech. Man's speech output mechanism is apparently species-specific.
Lesch-Nyhan Mutation: Prenatal Detection with Amniotic Fluid Cells
Authors: Demars Robert , Sarto Gloria , Felix Jeanette S. , Benke Paul
Published: October 2006

Cells cultured from the amniotic fluid of a 22-week fetus in a heterozygote for the X-linked Lesch-Nyhan mutation, which results in neurological and developmental disorders, lacked sex chromatin and were unable to incorporate hypoxanthine. The diagnosis of a mutant male was confirmed upon birth of enzyme-deficient, hyperuricemic twin boys whose amniotic membrane cells failed to incorporate hypoxanthine.
Generation of an Artificial Aurora
Authors: Hess Wilmot N.
Published: October 2006

On 26 January 1969 an Aerobee 350 rocket was fired from Wallops Island, Virginia, carrying an electron accelerator. Above 230 kilometers the electron guns put out a beam of 0.5 ampere of 10 kev electrons in pulses of 1-second duration aimed downward along the earth's magnetic field lines. The interaction of electron beam with the atmosphere at an altitude of about 100 kilometers generated enough light so that the auroral rays produced could be photographed on the ground by television camera systems.
Fission Track Age of Magnetic Anomaly 10: A New Point on the Sea-Floor Spreading Curve
Authors: Luyendyk Bruce P. , Fisher David E.
Published: October 2006

A portion of basaltic glass retrieved from an abyssal hill in the northeast Pacific has been dated by the fission track method. The sample location corresponds to magnetic anomaly 10 believed to have resulted from sea-floor spreading. The age of this sample is 35 ± 5 million years, which is in agreement with the previously proposed age of 31 to 32 million years based on linear extrapolation of measured recent spreading rates. This observation upholds the suggestions of other authors on the time variation of sea-floor spreading for the last 30 million years in various parts of the world ocean basin.
High-Resolution Autoradiography of Intracellular Plutonium
Authors: Lindenbaum Arthur , Smoler Martin H.
Published: October 2006

Intracellular incorporation of polymeric plutonium injected into mice was demonstrated in liver and spleen by electron-microscopic autoradiography. The observations are not inconsistent with other evidence indicating the association of plutonium with lysosomal components. Early results with a quantitative electron-microscopic technique may lead to microdosimetry of cells and cellular components.
Fossil Maize from Panama
Authors: Bartlett Alexandra S. , Barghoorn Elso S. , Berger Rainer
Published: October 2006

Wild maize, agricultural maize, and associated
Manihot
fossil pollen indicative of early agriculture after about 7300 years ago have been discovered in the Gatun basin, Panama. The course of rising sea level in the Canal Zone during the past 11,300 years is calculated.
Chemical Weathering in Central Iceland: An Analog of Pre-Silurian Weathering
Authors: Cawley J. L. , Burruss R. C. , Holland H. D.
Published: October 2006

The rate of chemical weathering in central Iceland is two to three times more rapid in areas with plant cover than in barren areas. This relatively small difference in chemical weathering rates suggests that atmospheric CO
2
pressures no greater than five times the present value were needed to sustain present-day rates of chemical weathering before the development of higher land plants in the Silurian.
Isopentenyladenosine Stimulates and Inhibits Mitosis of Human Lymphocytes Treated with Phytohemagglutinin
Authors: Gallo Robert C. , Whang-Peng Jacqueline , Perry Seymour
Published: October 2006

The plant cytokinin isopentenyladenosine, a component of yeast and mammalian transfer ribonucleic acid, is both a potent inhibitor and stimulator of DNA synthesis, transformation, and mitosis of the phytohemagglutinin-stimulated lymphocyte. The stage of the cell cycle and the concentrations used are critical for these effects. The addition of isopentenyladenosine within the first 12 hours after phytohemagglutinin at a concentration above 10
-6
molar results in inhibition, while lower concentrations (between 10
-7
and 10
-6
molar), added at 24 hours or later, have a stimulatory effect.
Potentially Lethal Radiation Damage: Repair by Mammalian Cells in Culture
Authors: Belli James A. , Shelton Merijean
Published: October 2006

Less than optimum conditions with regard to cell division after x-irradiation provide the necessary environment in which mammalian cells can repair potentially lethal radiation damage. The kinetics of repair suggest that, during the repair process, a transient, unstable cellular state occurs which prevents cell division in complete growth medium. The capacity for repair appears to be dependent on cell age.
Toad Urinary Bladder: Intercellular Spaces
Authors: DiBona D. R. , Civan M. M.
Published: October 2006

Vasopressin causes dilation of the intercellular spaces of the mucosal epithelium in toad bladder, an effect previously thought to result from enhanced net transepithelial water transport. Under conditions of zero net fluid transport, vasopressin exerted the same effect in seven tissues, which indicates that the width of the intercellular spaces cannot be taken as a reliable index of net transepithelial fluid transport.
Energized Configurations of Heart Mitochondria
in situ
Authors: Harris Robert A. , Williams Charles H. , Caldwell Monya , Green David E. , Valdivia Enrique
Published: October 2006

Changes in the configurational state of the cristal membranes of rat heart mitochondria within the living cell can be induced by imposing energizing conditions. An exact correlation has been established between the configurational states of the cristal membrane and the energy states of the mitochondrion. The configurational changes observed in mitochondria
in situ
are comparable to those established for beef heart mitochondria in vitro and are consistent with the postulate of the conformational basis of energy transductions in membrane systems. The formation of paracrystalline arrays is one of the noteworthy features of configurational changes of mitochondria
in situ
.
Blastocladia
and
Aqualinderella
: Fermentative Water Molds with High Carbon Dioxide Optima
Authors: Held Abraham A. , Emerson Ralph , Fuller Melvin S. , Gleason Frank H.
Published: October 2006

The uniflagellate aquatic phycomycete
Blastocladia ramosa
appears to be a facultative anaerobe.
Blastocladia pringsheimii
requires traces of oxygen. Growth of both species is no greater or only slightly greater at normal atmospheric oxygen pressure than under 0.2 percent oxygen pressure, but their growth is enhanced by the addition of 5 or 20 percent carbon dioxide. The cells of both species lack typical cristate mitochondria and contain only traces of cytochrome.
Blastocladia
resembles the biflagellate
Aqualinderella fermentans
in adaptation to an environment poor in oxygen and rich in carbon dioxide.
Erythropoiesis in the Dog: The Periodic Nature of the Steady State
Authors: Morley Alec , Stohlman Frederick
Published: October 2006

In at least six of 11 normal dogs serial measurement of reticulocyte counts showed oscillation with a period of approximately 14 days. The phase of oscillation could be altered by bleeding followed by retransfusion. The observations suggest that canine erythropoiesis is an example of a physiological rhythm which has its origin in homeostatic control.
Diorites from the Mid-Atlantic Ridge at 45°N
Authors: Aumento F.
Published: October 2006

Diorites, associated with basalts, basalt breccias, and serpentinized peridotites, occur in situ on the faulted scarps of two seamounts from the western High Fractured Plateau of the Mid-Atlantic Ridge at 45°N.
Heterogeneity of Presumably Homogeneous Protein Preparations
Authors: Susor Walter A. , Kochman Marion , Rutter William J.
Published: October 2006

Some highly purified glycolytic enzymes have been subjected to isoelectric focusing and found to contain a number of enzymatically active species. Crystalline aldolase A and glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle were resolved into five components, crystalline aldolase from yeast was resolved into three components, pyruvate kinase from rabbit muscle yielded four components, and yeast enolase was resolved into two components. Rabbit muscle lactate dehydrogenase (M
4
) gave one major peak of protein and enzymatic activity. The profiles of aldolase, glyceraldehyde-3-phosphate dehydrogenase, and yeast aldolases suggest random combinations of two closely related subunits into tetramers and dimers, respectively. The molecular heterogeneity of the other enzymes is not so easily related to subunit structure.
Mechanism of Assembly of the Tyrosyl Radical-Dinuclear Iron Cluster Cofactor of Ribonucleotide Reductase
Authors: Bollinger J. M. , Edmondson D. E. , Huynh B. H. , Filley J. , Norton J. R. , Stubbe J.
Published: October 2006

Incubation of the apoB2 subunit of
Escherichia coli
ribonucleotide reductase with Fe
2+
and O
2
produces native B2, which contains the tyrosyl radical-dinuclear iron cluster cofactor required for nucleotide reduction. The chemical mechanism of this reconstitution reaction was investigated by stopped-flow absorption spectroscopy and by rapid freeze-quench EPR (electron paramagnetic resonance) spectroscopy. Two novel intermediates have been detected in the reaction. The first exhibits a broad absorption band centered at 565 nanometers. Based on known model chemistry, this intermediate is proposed to be a μ-peroxodiferric complex. The second intermediate exhibits a broad absorption band centered at 360 nanometers and a sharp, isotropic EPR signal with
g
= 2.00. When the reaction is carried out with
57
Fe
2+
, this EPR signal is broadened, demonstrating that the intermediate is an iron-coupled radical. Variation of the ratio of Fe
2+
to B2 in the reaction and comparison of the rates of formation and decay of the intermediates to the rate of formation of the tyrosyl radical (⋅Y122) suggest that both intermediates can generate ⋅Y122. This conclusion is supported by the fact that both intermediates exhibit an increased lifetime in a mutant B2 subunit (B2-Y122F) lacking the oxidizable Y122. Based on these kinetic and spectroscopic data, a mechanism for the reaction is proposed. Unlike reactions catalyzed by heme-iron peroxidases, oxygenases, and model complexes, the reconstitution reaction appears not to involve high-valent iron intermediates.
Regulation of Kainate Receptors by cAMP-Dependent Protein Kinase and Phosphatases
Authors: Wang Lu-Yang , Salter M. W. , MacDonald J. F.
Published: October 2006

In the mammalian central nervous system, receptors for excitatory amino acid neurotransmitters such as the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-kainate receptor mediate a large fraction of excitatory transmission. Currents induced by activation of the AMPA-kainate receptor were potentiated by agents that specifically stimulate adenosine 3′,5′-monophosphate (cAMP)-dependent protein kinase A (PKA) activity or were supported by intracellular application of the catalytic subunit of PKA by itself or in combination with cAMP. Furthermore, depression of these currents by a competitive inhibitor of PKA indicates that AMPA-kainate receptors are regulated by endogenous PKA. Endogenous protein phosphatases also regulate these receptors because an inhibitor of cellular phosphatases enhanced kainate currents. Modulation of PKA and phosphatases may regulate the function of these receptors and thus contribute to synaptic plasticity in hippocampal neurons.
Cloning, Expression, and Gene Structure of a G Protein-Coupled Glutamate Receptor from Rat Brain
Authors: Houamed Khaled M. , Kuijper Joseph L. , Gilbert Teresa L. , Haldeman Betty A. , O'Hara Patrick J. , Mulvihill Eileen R. , Almers Wolfhard , Hagen Frederick S.
Published: October 2006

A complementary DNA encoding a G protein-coupled glutamate receptor from rat brain, Glu
G
R, was cloned by functional expression in
Xenopus
oocytes. The complementary DNA encodes a protein of 1199 amino acids containing a seven-transmembrane motif, flanked by large amino- and carboxyl-terminal domains. This receptor lacks any amino acid sequence similarity with other G protein-coupled receptors, suggesting that it may be a member of a new subfamily. The presence of two introns flanking the central core suggests that Glu
G
R may have evolved by exon shuffling. Expressed in oocytes, Glu
G
R is activated by quisqualate > glutamate > ibotenate >
trans
-1-aminocyclopentyl-1,3-dicarboxylate, and it is inhibited by 2-amino-3-phosphonopropionate. Activation is blocked by
Bordella pertussis
toxin. These properties are typical of some metabotropic glutamate receptors.
Energy Transfer Between Two Peptides Bound to One MHC Class II Molecule
Authors: Tampé Robert , Clark Brian R. , McConnell Harden M.
Published: October 2006

The 17-amino acid peptide from chicken ovalbumin, Ova(323-339), was labeled at the amino terminus with fluorescein [FOva(323-339)] and near the carboxyl terminus with Texas Red [AcOva(323-338)KTR]. Fluorescence spectroscopy was carried out on resolved electrophoretic bands on nonreducing polyacrylamide gels derived from incubation mixtures containing major histocompatibility complex (MHC) class II molecules IA
d
and the FOva(323-339)- and AcOva(323-338)KTR-labeled peptides. Energy transfer between fluorescein and Texas Red was observed in the "floppy" αβ heterodimer band, but not in the "compact" αβ heterodimer band. Energy transfer was detected between the truncated peptides FOva(323-328)CONH2 and AcOva(331-338)KTR in both the compact αβ and floppy αβ gel bands. The energy-transfer data suggest that the two binding sites of floppy αβ arise from splitting apart a putative large, single binding site region in compact αβ.
Viruses in Human Cancers
Authors: zur Hausen Harald
Published: October 2006

Viruses may contribute to the development of human tumors by different mechanisms: indirectly by inducing immunosuppression or by modifying the host cell genome without persistence of viral DNA; directly by inducing oncoproteins or by altering the expression of host cell proteins at the site of viral DNA integration. Human cancers associated with papillomavirus, hepatitis B virus, Epstein-Barr virus, and human T cell leukemia-lymphoma virus infections are responsible for approximately 15 percent of the worldwide cancer incidence. Cancer of the cervix and hepatocellular carcinoma account for about 80 percent of virus-linked cancers. Because experimental and epidemiologic data imply a causative role for viruses, particularly in cervical and liver cancer, viruses must be thought of as the second most important risk factor for cancer development in humans, exceeded only by tobacco consumption.
Visceral and Behavioral Responses to Intraduodenal Fat
Authors: Fara John W. , Rubinstein Eduardo H. , Sonnenschein Ralph R.
Published: October 2006

Introduction of milk or corn oil into the duodenum of the cat evokes an increase in superior mesenteric blood flow (blocked by atropine), an inhibition of gastric and duodenal motility, and sedation. Cholecystokinin-pancreozymin mimics the mesenteric vascular effect of intraduodenal fat and seems to have a sedating action.
Spectrographic Detection of Topographic Features on Mars
Authors: Belton Michael J. S. , Hunten Donald M.
Published: October 2006

Observations of the martian carbon dioxide band at 1.05 microns made with a three-channel multislit spectrophotometer indicate gross height variations in the vicinity of Syrtis Major and surrounding desert regions. Syrtis Major appears to be very high with essentially no detectable carbon dioxide above it. The data appear to confirm local trends and, in magnitude at least, the large variations of height found in earlier radar observations. A one-to-one correlation of height with albedo is not evident in the results. Elevated areas are found in both desert and dark regions. In several regions dark areas are associated with relatively steep slopes.
Current-Voltage Relations during Illumination: Photoreceptor Membrane of a Barnacle
Authors: Brown H. Mack , Meech Robert W. , Koike Hiroyuki , Hagiwara Susumu
Published: October 2006

In voltage clamped photoreceptor cells of the barnacle, light-induced membrane current varied nonlinearly with membrane potential and changed sign at about + 27 millivolts (reversal potential) independently of light intensity. Instantaneous current-voltage relations were linear and intersected the voltage axis at the reversal potential. Illumination increased membrane conductance that was dependent on membrane potential, light intensity, and time.
Luteinizing Hormone-Releasing Activity in Hypophysial Stalk Blood and Elevation by Dopamine
Authors: Kamberi Ibrahim A. , Mical Renon S. , Porter John C.
Published: October 2006

Pituitary halves incubated in pituitary stalk plasma release more luteinizing hormone than their opposite halves incubated in plasma from peripheral blood. Glands incubated in stalk plasma from dopamine-treated rats release more luteinizing hormone than glands incubated in stalk plasma from untreated controls. Luteinizing hormone-releasing activity in stalk plasma may be due to the luteinizing hormone-releasing factor, and the secretion of luteinizing hormone-releasing factor may be controlled by a dopaminergic mechanism.
Antiparkinsonian Drugs: Inhibition of Dopamine Uptake in the Corpus Striatum as a Possible Mechanism of Action
Authors: Coyle Joseph T. , Snyder Solomon H.
Published: October 2006

A variety of antiparkinsonian drugs are potent, noncompetitive inhibitors of dopamine uptake into synaptosomes in homogenates of rat corpus striatum. Inhibition of dopamine uptake may potentiate the synaptic actions of dopamine in the striatum and could explain the antiparkinsonian effects of these drugs. This hypothesis accounts for several clinical features of Parkinson's disease and predicts compounds which may be new therapeutic agents.
Changing Sensitivity of the Pubertal Gonadal Hypothalamic Feedback Mechanism in Man
Authors: Kulin Howard E. , Grumbach Melvin M. , Kaplan Selna L.
Published: October 2006

Clomiphene citrate in doses which stimulate gonadotropin production in the adult suppresses urinary follicle stimulating hormone (FSH) excretion and plasma testosterone concentration in prepubertal children. Such results indicate that feedback between gonad and hypothalamus is operative and highly sensitive in prepubertal humans. Puberty in man, as in the rat, is accompanied by a decrease in the sensitivity of the feedback mechanism.
Corticosterone Regulation of Tryptophan Hydroxylase in Midbrain of the Rat
Authors: Azmitia Efrain C. , McEwen Bruce S.
Published: October 2006

The tryptophan hydroxylase activity in the rat midbrain decreases after adrenalectomy and is restored by treatment with corticosterone. Cycloheximide, administered intracisternally, prevents the restoration of the enzyme activity by corticosterone. Cycloheximide administration to adrenalectomized rats results in a further decrease in the enzyme activity. an indication that the enzyme has a rapid turnover even in the absence of corticosterone.
Olfactory Stimuli and the "Pseudo-Extinction" Effect
Authors: Wasserman Edward A. , Jensen Donald D.
Published: October 2006

Continuously rewarded rats show a decrease in running speed on a runway recently traversed by other rats undergoing experimental extinction. This "pseudo-extinction" effect is caused by discriminable odors emitted by extinction subjects. These odors could be confounding variables in studies using forms of aversive stimulation.
Synthetic Juvenile Hormone: Induction of Sex Pheromone Production in
Ips confusus
Authors: Boriden John H. , Nair K. K. , Slater Catherine E.
Published: October 2006

Topical application of 25, 50, or 100 micrograms of 10,11-epoxyfarnesenic acid methyl ester in peanut oil induced male
Ips confusus
to produce sex pheromone in the hindgut Malpighian tubule region. Twenty-four hours after treatment of male beetles with 100 micrograms of hormone, their hindgut Malpighian tubule extract was more attractive to female beetles in a laboratory bioassay than was extract from males producing pheromone naturally in ponderosa pine logs.
Cockroach Leg Regeneration: Effects of Ecdysterone in vitro
Authors: Marks E. P. , Leopold R. A.
Published: October 2006

Regenerating epithelial tissue from the cockroach leg forms two cuticular coverings. The first of these consists of a protein-carbohydrate complex that is replaced before molting. The second covering represents the cuticle containing chitin. The deposition of the cuticle can be induced in vitro by adding ecdysterone to the culture medium.
Polyinosinic-Polycytidylic Acid Inhibits Chemically Induced Tumorigenesis in Mouse Skin
Authors: Gelboin H. V. , Levy H. B.
Published: October 2006

Polyinosinic-polycytidylic acid administered intraperitoneally inhibits (i) the formation of skin tumors induced by a single topical application of 9,10-dimethylbenzanthracene followed by weekly applications of croton oil and (ii) the formation of skin tumors induced by a single large application of 9,10-dimethylbenzanthracene.
Critical Flicker-Fusion of Solid and Annular Stimuli
Authors: Robinson Daniel N.
Published: October 2006

Critical flicker-fusion thresholds were measured with both solid disks and annular stimuli. The former subtended 1, 4, and 8 degrees of visual angle, and the latter subtended 4 and 8 degrees. The illuminated region of the 4-degree annulus provided the same area of stimulation as that of the 1-degree disk. The illuminated region of the 8-degree annulus provided the same area of stimulation as the 4-degree disk. Annular stimuli significantly reduced critical flicker-fusion thresholds relative to those obtained with disk stimuli of the same area. The effects are not explicable in terms of heterogeneous retinal sensitivity. Laws relating critical flicker-fusion to area seem to be valid only under the restricted condition of homogeneous stimulation.
Early Experience Effects upon Cortical Dendrites: A Proposed Model for Development
Authors: Schapiro Shawn , Vukovich Katherine R.
Published: October 2006

We studied the effects of environmental stimulation on the development of rat cortical pyramidal cell synaptic loci (dendritic spines) and the number of such cells staining by the rapid Golgi technique. Stimulation three to five times a day from the day of birth increased the number of spines per micrometer in 8-day-old animals and increased the number of neurons staining at 8 to 16 days of age. This effect of afferent input upon development of the dendritic spine may represent the neuroanatomical basis for the influence of early experience on subsequent behavior. The number of neurons staining by the rapid Golgi technique appears to be related to those that are functionally involved at the time of tissue preparation.
Passive Seismic Experiment
Authors: Latham Gary V. , Ewing Maurice , Press Frank , Sutton George , Dorman James , Nakamura Yosio , Toksöz Nafi , Wiggins Ralph , Derr John , Duennebier Frederick
Published: October 2006

Seismometer operation for 21 days at Tranquillity Base revealed, among strong signals produced by the Apollo 11 lunar module descent stage, a small proportion of probable natural seismic signals. The latter are long-duration, emergent oscillations which lack the discrete phases and coherence of earthquake signals. From similarity with the impact signal of the Apollo 12 ascent stage, they are thought to be produced by meteoroid impacts or shallow moonquakes. This signal character may imply transmission with high
Q
and intense wave scattering, conditions which are mutually exclusive on earth. Natural background noise is very much smaller than on earth, and lunar tectonism may be very low.
Rubidium-Strontium Age and Elemental and Isotopic Abundances of Some Trace Elements in Lunar Samples
Authors: Murthy V. Rama , Schmitt R. A. , Rey P.
Published: October 2006

Data on six lunar crystalline rocks give an apparent Rb-Sr isochron age of 4.42 ± 0.24 × 10
9
years (95 percent confidence limits) and initial
87
Sr/
86
Sr ratio similar to that in a basaltic achondrite. Relationships between K, Rb, Sr, and Ba and depletion of Eu in these samples point to plagioclase separation from the melts that produced these rocks. The abundance of
157
Gd in the three lunar samples is similar to terrestrial abundance within < 0.2 percent, thus setting a limit of < 6 × 10
15
neutrons per square centimeter for the integrated thermal neutron flux difference between lunar and terrestrial materials.
18
O/
16
O,
30
Si/
28
Si, D/H, and
13
C/
12
C Studies of Lunar Rocks and Minerals
Authors: Epstein Samuel , Taylor Hugh P.
Published: October 2006

The δ
18
O of minerals from lunar gabbros and basalts are: plagioclases +6.06 to +6.33), pyroxenes (+5.70 to +5.95), and ilmenites (+3.85 to +4.12). The uniformity of these results indicates isotopic equilibrium in the mineral assemblages. Estimated plagioclase-ilmenite temperautres range from 1150°C to 1340°C. The bulk
18
/
16
O and
30
Si/
28
Si ratios of these lunar rocks are identical with ratios of terrestrial basalts, but the lunar glass, breccia, and dust are slightly enriched in the heavier isotopes. The lunar hydrogen (formed from solar wind) has a δ D/H of less than—873 per mil and the value may be even lower, as it is probably contaminated with terrestrial hydrogen. The δ
13
C of lunar dust and breccia is unusually high relative to reduced carbon in meteorites or on earth.
Petrographic, Mineralogic, and X-Ray Fluorescence Analysis of Lunar Igneous-Type Rocks and Spherules
Authors: Brown G. Malcolm , Emeleus C. Henry , Holland J. Grenville , Phillips Roy
Published: October 2006

Three lunar rocks show almost identical mineralogy but grain sizes that vary from basaltic to gabbroic. Clinopyroxene is zoned from augite to subcalcic ferroaugite compositions and is accompanied by decrease in Cr, Al, and Ti. Plagioclase is zoned from 93 to 78 percent anorthite. Olivine (68 percent forsterite) is present in one rock and apatite is rare. Cristobalite, ilmenite with Ti-rich lamellae, ulvöspinel (often Cr-rich), troilite, and kamacite are low in trace elements. Glassy spherules are of basaltic or feldspathic (92 percent anorthite) composition but contain abundant iron spheres of taenite composition (13 percent Ni). Four rock analyses by x-ray fluorescence show affinity with terrestrial basalts but with anomalous amounts of Ti, Na, Cr, Zr, Y, Rb, Nb, Ni, Cu, and Zn.
Compositional Zoning and Its Significance in Pyroxenes from Three Coarse-Grained Lunar Samples
Authors: Hargraves R. B. , Hollister L. S. , Otalora G.
Published: October 2006

The calcium-rich pyroxenes in lunar samples 10047, 10058, and 10062 show pronounced sectoral and radial compositional variations which correlate with sharp to gradual variations in color and optical properties. The pyroxenes apparently grew as nearly euhedral crystals from melts of approximately the same composition as that of the samples. The coupled substitutions determined across sector boundaries suggest that Al is predominantly in the tetrahedral site and that Ti is predominantly quadrivalent. The pyroxene differentiation trend (unknown in terrestrial pyroxenes) is toward extreme enrichment in the ferrosilite molecule. The iron-enriched portions of the pyroxene grains may have grown with a triclinic pyroxenoid structure.
Striated Muscle Fibers: Inactivation of Contraction Induced by Shortening
Authors: Taylor Stuart R. , Rüdel Reinhardt
Published: October 2006

The myofibrils in an isolated muscle fiber remain straight during the early part of a lightly loaded contraction initiated by membrane depolarization, but, as shortening continues, myofibrils in the core of the fiber become wavy, which suggests that their activation has been interrupted by shortening of the fiber. This may be a factor determining the length-tension relation at short muscle lengths.
Discrimination by Rats of Conspecific Odors of Reward and Nonreward
Authors: Morrison Robert R. , Ludvigson H. Wayne
Published: October 2006

The hypothesis that, after receiving reward and nonreward, rats excrete differential odors perceptible to other rats was tested by making the correct turn in a T-maze contingent on discrimination of any such odors. Clear evidence for an "odor of nonreward or frustration" was obtained, and there was the suggestion of a transistory odor after early reward trials.
Directional Hearing: Effect of Unilateral Change of the Sound Duration
Authors: Alexeenko N. Y.
Published: October 2006

Monaural change of the duration of a binaural acoustic stimulus within the range of 0.5 to 1.5 milliseconds caused a considerable shift of the sound image. This could be counterbalanced by a unilateral change of the signal intensity. Further unilateral lengthening of the stimulus did not affect the sound localization, but it revealed a masking aftereffect (4 to 10 milliseconds) of the binaural signal. The data define the temporal characteristics of binaural effect formation and the relative importance of duration and intensity parameters at different stages of binaural interaction.
Refractory Oxide-Metal Composites: Scanning Electron Microscopy and X-ray Diffraction of Uranium Dioxide-Tungsten
Authors: Gerdes R. J. , Chapman A. T. , Clark G. W.
Published: October 2006

Unidirectional solidification of a melt, consisting of uranium dioxide and 5 to 15 percent by weight of tungsten, formed well-ordered arrangements of tungsten fibers or platelets in the uranium dioxide matrix. Fiber shape and orientation relations of the components indicate the development of several dominant growth modes.
Magnetic Particles Extracted from Manganese Nodules: Suggested Origin from Stony and Iron Meteorites
Authors: Finkelman Robert B.
Published: October 2006

On the basis of x-ray diffraction and electron microprobe data, spherical and ellipsoidal particles extracted from manganese nodules were divided into three groups. Group I particles are believed to be derived from iron meteorites, and Group II particles from stony meteorites. Group III particles are believed to be volcanic in origin.
Fetal Response to Viral Infection: Interferon Production in Sheep
Authors: Overall James C. , Glasgow Lowell A.
Published: October 2006

When virus was inoculated intravenously during the third trimester, the gestating ewe produced only low amounts of serum interferon, whereas the fetal lamb had the capacity to produce extremely high amounts. There was no evidence of transplacental transfer of interferon between mother and fetus in either direction.
Mixed Lymphocyte Reactions and Tissue Transplantation Tolerance
Authors: Silvers Willys K. , Lubaroff David M. , Wilson Darcy B. , Fox Dianne
Published: October 2006

The induction of tolerance of Lewis histocompatibility antigens in BN rats inoculated at birth with BN/Lewis F
1
hybrid bone marrow cells, as revealed by the prolonged survival of Lewis skin grafts, is accompanied by markedly decreased reactivity in the mixed lymphocyte interaction. Blood lymphocytes from animals inoculated with lymph node cell suspensions also display diminished proliferative reactivity to hybrid BN/Lewis cells in the interaction. However, these recipients are not tolerant of Lewis skin grafts. Blood lymphocytes from BN rats inoculated neonatally with Lewis thymocytes fail to display any level of unresponsiveness in vitro, and such animals are not tolerant of Lewis skin grafts. The results suggest that in rats skin and marrow cells have histocompatibility antigens that are absent or poorly expressed on lymph node cells and thymocytes.
Viscosity of Lunar Lavas
Authors: Murase Tsutomu , McBirney Alexander R.
Published: October 2006

The viscosity of a synthetic silicate liquid with the composition of a lunar rock has been determined experimentally and found to be lower than that of any previously studied volcanic rock on earth. This fact suggests that lunar lava flows will be very thin and extensive unless they are ponded, and that lava tubes should be common and of larger dimensions than those on earth. Coarse crystallinity can be a feature of rapidly cooled surface lavas.
Line and Grade in the Extinct Medius Species Group of
Sigmodon
Authors: Martin Robert A.
Published: October 2006

Remains of
Sigmodon minor
and
Sigmodon medius
, extinct cotton rats comprising the
medius
species group, have been recovered from both Kansas and Arizona.
Sigmodon minor
evolved from
Sigmodon medius
, and the available evidence suggests that Kansas populations of
Sigmodon minor
were derived from Kansas populations of
Sigmodon medius
, while Arizona populations of
Sigmodon minor
were derived from Arizona populations of
Sigmodon medius
. This multiple origin of a single mammalian species is similar to the origin proposed by Carleton Coon for the races (subspecies) of
Homo sapiens
.
Tumbaga Object from the Early Classic Period, Found at Altun Ha, British Honduras (Belize)
Authors: Pendergast D. M.
Published: October 2006

Excavations at Altun Ha, British Honduras (Belize), have yielded a claw-shaped bead of tumbaga, a gold-copper alloy, occurring as part of an Early Classic offering. Stratigraphic evidence plus radiocarbon dates place the cache at or before A.D. 500, and stylistic elements indicate a source for the bead in the Coclé culture of central Panama.
Bradykinin Inhibition by Butylated Hydroxyanisole
Authors: Posati Linda P. , Pallansch Michael J.
Published: October 2006

Concentrations of butylated hydroxyanisole as low as 8 × 10
-9
mole per liter can inhibit detectably the contraction of smooth muscle elicited by bradykinin. The mechanism of the inhibitory effect of this food grade anti-oxidant is apparently complex, and the effect is only partially reversible.
Recovery of Neuronal Function after Prolonged Cerebral Ischemia
Authors: Hossmann K. -A. , Sato K.
Published: October 2006

Cats were submitted to complete cerebral ischemia by clamping the innominate and subclavian arteries and simultaneously lowering the systemic blood pressure. Neuronal function was assessed by recording the electroencephalogram and the anti- and orthodromic activation of the pyramidal tract. A full recovery of the pyramidal response and even of evoked electroencephalographic activity occurred after ischemia of more than 1 hour's duration.
Hormone-Sensitive Adenyl Cyclase: Cytochemical Localization in Rat Liver
Authors: Reik Louis , Petzold Gary L. , Higgins Joan A. , Greengard Paul , Barrnett Russell J.
Published: October 2006

An electron microscopic procedure has been developed, using rat liver, for the localization of hormone-sensitive adenyl cyclase. Isoproterenol-sensitive adenyl cyclase is located almost exclusively in the parenchymal cells. In contrast, glucagon-sensitive adenyl cyclase is located primarily in the reticuloendothelial cells but is also present in parenchymal cells. Sodium fluoride-sensitive adenyl cyclase is found in both cell types.
Murine Sarcoma Virus: The Question of Defectiveness
Authors: Parkman Robertson , Levy Jay A. , Ting Robert C.
Published: October 2006

Infection of mouse and rat cells by the murine sarcoma virus (Moloney isolate) showed two-hit kinetics for focus production in mouse cells but one-hit kinetics in rat cells. Antiserum added to cultures after infection suppressed focus formation in mouse cells but not in rat cells. These studies suggest that, in rat cells infected with murine sarcoma virus, leukemia virus is not needed for focus formation and that these foci result from proliferation of the transformed rat cell; in mouse cells, on the other hand, leukemia virus is needed as "helper," and focus formation requires spread of virus. The term "defectiveness" then, if used, should not be applied to RNA tumor viruses without qualification for the viral function studied and the cell system employed.
Polywater: Possibility of
p
-Electron Delocalization
Authors: Messmer Richard P.
Published: October 2006

p
-Electron delocalization may be important in determining the stability of the symmetric hydrogen bonds in a recently proposed model of "polywater."
Coincidence of Climatic and Faunal Fluctuations in Pleistocene Bermuda
Authors: Gould Stephen Jay
Published: October 2006

As the climate of Pleistocene Bermuda oscillated during the last two glacial cycles, coincident variation occurred for a variety of independent events in the form and diversity of land snails. This variation was influenced primarily by the availability of calcium carbonate for shell construction.
Antennal Receptors: Reactions to Female Sex Attractant in
Periplaneta americana
Authors: Boeckh Jürgen , Sass Hinrich , Wharton Denis R. A.
Published: October 2006

In
Periplaneta americana
, olfactory receptors on the antennae of male adults and nymphs respond at low threshold to the specific natural odorous attractant produced by virgin females. There are no receptors for that odor on the antennae of female adults or nymphs of any instar.
Circadian Clock in Insect Photoperiodism
Authors: Saunders D. S.
Published: October 2006

Night-interruption experiments with the wasp
Nasonia vitripennis
maintained in 48- and 72-hour light: dark cycles reveal two and three peaks of light sensitivity (diapause inhibition), respectively. The first peak is 19 hours after lights-on in all regimes tested; the later peaks occur at 24-hour intervals thereafter, providing evidence for the circadian nature of the photoperiodic clock in this insect.
Retinoscopy and Eye Size
Authors: Glickstein Mitchell , Millodot Michel
Published: October 2006

Retinoscopy was performed on animals with different sized eyes, all of whom appeared hypermetropic. The data were well fitted by an equation of the form
y
=
kx
-2
where
y
is refractive error in diopters, and
x
is the corneo-retinal length of the eye. Apparent hypermetropia may be due to the reflection from the inner surface of the retina.
Filamentary Crystal Growth Associated with Impact Craters from Hypervelocity Microparticles
Authors: Berg Otto E. , McDonnell J. A. M.
Published: October 2006

A filamentary crystal growth is associated with impacts of hypervelocity microparticles upon copper foil. They are copper whiskers formed by the condensation of the target material vaporzied by the impact.
On the Apparent Homology of Actin and Tubulin
Authors: Stephens R. E.
Published: October 2006

Muscle actin and ciliary A-tubulin from
Pecten irradians
have molecular weights of 46,000 and 59,000, respectively, as measured by sodium lauryl sulfate—polyacrylamide-gel electrophoresis. Tryptic and chymotryptic peptides obtained from these proteins are very dissimilar, indicating that there is little significant homology.
Human Cystinosis: Intracellular Deposition of Cystine
Authors: Hummeler Klaus , Zajac Barbara A. , Genel Myron , Holtzapple Philip G. , Segal Stanton
Published: October 2006

Membrane-limited inclusions were found in the cytoplasm of cells of the rectal mucosa, leukocytes, and cultured fibroblasts from two humans with cystinosis. Most of the inclusions contained amorphous material, presumably cystine. In cells of the rectal mucosa the material appeared frequently crystallized. This was rarely seen in leukocytes, and never in cultured fibroblasts. The fact that acid phosphatase could be demonstrated consistently in the organelles responsible for sequestration of cystine indicates that they are lysosomes.