bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphorylation of the GABAa/Benzodiazepine Receptor α Subunit by a Receptor‐Associated Protein Kinase
Authors: Sweetnam Paul M. , Lloyd Jack , Gallombardo Peter , Malison Robert T. , Gallager Dorothy W. , Tallman John F. , Nestler Eric J.
Published: October 2006

Abstract: Partially purified preparations of GABAa/benzodiazepine receptor from rat brain were found to contain high levels of a protein kinase activity that phosphorylated a small number of proteins in the receptor preparations, including a 50‐kilodalton (kD) phosphoprotein that comigrated on two‐dimensional electrophoresis with purified, immunolabeled, and photolabeled receptor α subunit. Further evidence that the comigrating 50‐kD phosphoprotein was, in fact, the receptor α subunit was obtained by peptide mapping analysis: the 50‐kD phosphoprotein yielded one‐dimensional peptide maps identical to those obtained from iodinated, purified α subunit. Phosphoamino acid analysis revealed that the receptor α subunit is phosphorylated on serine residues by the protein kinase activity present in receptor preparations. Preliminary characterization of the receptor‐associated protein kinase activity suggested that it may be a second messenger‐independent protein kinase. Protein kinase activity was unaltered by cyclic AMP, cyclic GMP, calcium plus calmodulin, calcium plus phosphatidylserine, and various inhibitors of these protein kinases. Examination of the substrate specificity of the receptor‐associated protein kinase indicated that the enzyme preferred basic proteins as substrates. Endogenous phosphorylation experiments indicated that the receptor α subunit may also be phosphorylated in crude membranes by a protein kinase activity present in those membranes. As with phosphorylation of the receptor in purified preparations, its phosphorylation in crude membranes also appeared to be unaffected by activators and inhibitors of second messenger‐dependent protein kinases. These findings raise the possibility that the phosphorylation of the α subunit of the GABAa/ benzodiazepine receptor by a receptor‐associated protein kinase plays a role in modulating the physiological activity of the receptor in vivo.
ADP‐Ribosylation with Pertussis Toxin Modulates the GTP‐Sensitive Opioid Ligand Binding in Digitonin‐Soluble Extracts of Rat Brain Membranes
Authors: Wong Yung H. , Demoliou‐Mason Catherine D. , Barnard Eric A.
Published: October 2006

Pertussis toxin‐catalyzed ADP‐ribosylation of the guanine nucleotide‐binding proteins Gi and Go is shown to proceed in Mg2+‐digitonin extracts from rat brain; the Mr 41,000 and Mr 39,000 peptides are labelled there as in the membranes. The ADP‐ribosylation in detergent solution retains the differential sensitivity to guanine nucleotide analogues. This reaction also removes the partial inhibition by the guanine nucleotides of the binding of opioid agonists, as does the same treatment in the membranes. The partial inhibition of agonist binding by Na+, however, is left unchanged. The binding of the antagonist naloxone is little affected by Na+ or by guanine nucleotides in the treated membranes, but the treated soluble receptors show an enhanced binding in high‐Na+ medium, although still guanine nucleotide insensitive. The data suggest that the toxin reaction in the absence of guanine nucleotides and agonist stabilizes the opioid receptor in a receptor‐G‐protein coupled state which is no longer sensitive to guanine nucleotides but retains its sensitivity to the Na+ ions.
Acidosis, Acetazolamide, and Amiloride: Effects on 22Na Transfer Across the Blood‐Brain and Blood‐CSF Barriers
Authors: Murphy Vincent A. , Johanson Conrad E.
Published: October 2006

Abstract Sprague‐Dawley rats were given treatments, known to decrease 22Na movement into choroid plexus and CSF, to investigate their effect on 22Na transfer across the cerebral capillaries. Acidic salts, acetazolamide, or amiloride was injected intraperitoneally into bilaterally nephrectomized rats, and the rate of 22Na uptake into parietal cortex, pons‐medulla, and CSF was determined at 12, 18, and 24 min. Severe acidosis (arterial pH 7.2), produced by HCl injection, decreased the rate of 22Na entry into both brain regions and CSF by 25%, whereas mild acidosis (pH 7.3) from NH.,C1 injection reduced brain entry by 18%, but CSF entry by only 10%. Like HCl acidosis, amiloride reduced transport into both brain and CSF by 22%. Penetration of 22Na into parietal cortex was unchanged by acetazolamide, but that into CSF was slowed 30%. Since uptake of 22Na into cortical regions is primarily movement of tracer across the cerebral capillaries when tracer uptake time is <30 min, the results indicate that both metabolic acidosis and amiloride decrease Na+ permeativity at the cerebral capillaries as well as at the choroid plexus. Acetazolamide, on the other hand, alters Na+ movement only across the choroidal epithelium.
Lipid Metabolism During Early Stages of Wallerian Degeneration in the Rat Sciatic Nerve
Authors: White Frances V , Toews Arrel D. , Goodrum Jeffry F. , Novicki Deborah L. , Bouldin Thomas W. , Morell Pierre
Published: October 2006

Abstract We examined changes in biosynthetic capacity of sciatic nerve during the early stages of Wallerian degeneration, utilizing a model that permits exclusion of nonresident cells from degenerating nerve. Sciatic nerve segments were placed in either 5‐μm pore (allowing infiltration of nonresident cells) or 0.22‐μm pore (excluding nonresident cells) Millipore diffusion chambers and then implanted in the peritoneal cavity of the same 32‐34‐day‐old rat. At times up to 7 days post‐surgery, nerve segments from the chambers, as well as control segments from the contralateral sciatic nerve, were removed and their capacity to incorporate radioactive precursors into lipids and proteins assayed in vitro. In nerve segments from both the 0.22‐ and 5‐μm pore chambers, incorporation of [14C]acetate into total lipids was decreased relative to control by 50% at 12 h postsurgery and by 85% at day 3. This decreased incorporation of [14C]acetate reflects primarily decreased de novo synthesis of cholesterol and of fatty acyl residues incorporated into glycerolipids and sphingolipids. There was a preferentially decreased synthesis of cerebrosides and cholesterol (components enriched in myelin) relative to other lipids, while cholesterol esters and free fatty acids (products of membrane degradation) accounted for a greater proportion of the greatly reduced levels of total lipid label. In contrast to [14C]acetate, incorporation of [3H]glycerol into lipids was increased up to fourfold, relative to control, 1 day after nerve transection. This increased incorporation of [3H]glycerol does not reflect de novo synthesis of lipids (which is decreased), but rather removal of toxic fatty acyl residues derived from degradation of myelin lipids; these toxic compounds must be removed by resynthesis into nonmyelin glycerolipids and cholesterol esters. The inhibition of de novo synthesis of myelin lipids in Schwann cells during the early stages of Wallerian degeneration occurs independently of hematogenously‐derived cells. We suggest that Wallerian degeneration rapidly results in some breakdown of myelin, and that the increased free fatty acid levels resulting from degradation of myelin lipids inhibit the de novo synthesis of new myelin lipid.
Effect of Dichloroacetate on Regional Energy Metabolites and Pyruvate Dehydrogenase Activity During Ischemia and Reperfusion in Gerbil Brain
Authors: Katayama Yasuo , Welsh Frank A.
Published: October 2006

Abstract: The objective of this study was to determine whether administration of dichloroacetate (DCA), an activator of pyruvate dehydrogenase (PDH), improves recovery of energy metabolites following transient cerebral ischemia. Gerbils were pretreated with DCA, and cerebral ischemia was produced using bilateral carotid artery occlusion for 20 min, followed by reperfusion up to 4 h. DCA had no effect on the accumulation of lactic acid and the decrease in ATP and phosphocreatine (PCr) during the 20‐min insult, nor on the recovery of these metabolites measured at 20 and 60 min reperfusion. However, at 4 h reperfusion, levels of ATP and PCr were significantly higher in DCA‐treated animals than in controls, as PCr exhibited a secondary decrease in caudate nucleus of control animals. PDH was markedly inhibited at 20 min reperfusion in both groups, but was reactivated to a greater extent in DCA‐treated animals at 60 min and 4 h reperfusion. These results demonstrate that DCA had no effect on the initial recovery of metabolites following transient ischemia. However, later in reperfusion, DCA enhanced the postischemic reactivation of PDH and prevented the secondary failure of energy metabolism in caudate nucleus. Thus, inhibition of PDH may limit the recovery of energy metabolism following cerebral ischemia.
Thymopoietin, a Thymic Polypeptide, Specifically Interacts at Neuronal Nicotinic α‐Bungarotoxin Receptors
Authors: Quik M. , Afar R. , Audhya T. , Goldstein G.
Published: October 2006

Abstract: α‐Bungarotoxin (α‐BGT), a snake venom polypeptide, interacts potently and specifically with a nicotinic receptor population in neuronal tissue. However, the identity of this site is unclear, because, unlike at the neuromuscular junction and in electroplax, in nervous tissue the toxin does not block nicotinic cholinergic responses. Therefore, we sought endogenous compounds other than acetylcholine that could interact with the neuronal α‐BGT site. In the present experiments, thymopoietin, a polypeptide isolated from the thymus, is shown to inhibit potently α‐BGT binding to brain membranes in a dose‐dependent manner (IC50= 3.1 nM). This effect was not shared by a wide variety of other peptides, including thysplenin, a closely related polypeptide. Thymopoietin did not inhibit the binding of other radioligands known to interact with different populations of cholinergic receptors, such as [3H]nicotine and [3H]methylcarbachol, which bind to nicotinic receptors, or [3H]quinuclidinylbenzilate, which binds to muscarinic receptors. These results show that thymopoietin potently and specifically affects l25I‐α‐BGT binding to brain membranes and suggest that thymopoietin might be an endogenous ligand for α‐BGT receptors in neuronal tissue.
γ‐Hydroxybutyrate Stimulation of the Formation of Cyclic GMP and Inositol Phosphates in Rat Hippocampal Slices
Authors: Vayer Philippe , Maitre Michel
Published: October 2006

Abstract: The presence of γ‐hydroxybutyrate (GHB) (300–600 μM) in the incubation medium of rat hippocampal slices led to an increase of intracellular cyclic GMP and inositol phosphates. This phenomenon is dependent on the time and the dose of GHB used and might be the result of the stimulation of GHB receptor sites which are abundant in rat hippocampus. The increase of cyclic GMP and inositol phosphates is blocked by some anticonvulsants and opiate antagonists. These results seems to indicate that, like many substances inducing epileptic phenomena, GHB provokes neuronal depolarization in hippocampus which is accompanied by formation of cyclic GMP and inositol phosphates. The effect of opiate antagonists can be explained by the possible implication of an opiate synapse which mediates GHB effects in rat hippocampus.
Most Synaptic Vesicles Isolated from Rat Brain Carry Three Membrane Proteins, SV2, Synaptophysin, and p65
Authors: Floor E. , Feist B. E.
Published: October 2006

Abstract: We have prepared highly purified synaptic vesicles from rat brain by subjecting vesicles purified by our previous method to a further fractionation step, i.e., equilibrium centrifugation on a Ficoll gradient. Monoclonal antibodies to three membrane proteins enriched in synaptic vesicles—SV2, synaptophysin, and p65—each were able to immunoprecipitate specifically ∼90% of the total membrane protein from Ficoll‐purified synaptic vesicle preparations. Anti‐SV2 precipitated 96% of protein, anti‐synaptophysin 92%, and antip65 83%. These results demonstrate two points: (1) Ficollpurified synaptic vesicles appear to be >90% pure, i.e., < 10% of membranes in the preparation do not carry synaptic vesicleassociated proteins. These very pure synaptic vesicles may be useful for direct biochemical analyses of mammalian synaptic vesicle composition and function. (2) SV2, synaptophysin, and p65 coexist on most rat brain synaptic vesicles. This result suggests that the functions of these proteins are common to most brain synaptic vesicles. However, if SV2, synaptophysin, or p65 is involved in synaptic vesicle dynamics, e.g., in vesicle trafficking or exocytosis, separate cellular systems are very likely required to modulate the activity of such proteins in a temporally or spatially specific manner.
Activation of Glutamate Dehydrogenase by Leucine and Its Nonmetabolizable Analogue in Rat Brain Synaptosomes
Authors: Erecińska Maria , Nelson David
Published: October 2006

Leucine and β‐(±)‐2‐aminobicyclo[2.2.1]heptane‐2‐carboxylic acid (BCH) stimulated, in a dose‐dependent manner, reductive amination of 2‐oxoglutarate in rat brain synaptosomes treated with Triton X‐100. The concentration dependence curves were sigmoid, with 10–15‐fold stimulations at 15 mM leucine (or BCH); oxidative deamination of glutamate also was enhanced, albeit less. In intact synaptosomes, leucine and BCH elevated oxygen uptake and increased ammonia formation, consistent with stimulation of glutamate dehydrogenase (GDH). Enhancement of oxidative deamination was seen with endogenous as well as exogenous glutamate and with glutamate generated inside synaptosomes from added glutamine. With endogenous glutamate, the stimulation of oxidative deamination was accompanied by a decrease in aspartate formation, which suggests a concomitant reduction in flux through aspartate aminotransferase. Activation of reductive amination of 2‐oxoglutarate by BCH or leucine could not be demonstrated even in synaptosomes depleted of internal glutamate. It is suggested that GDH in synaptosomes functions in the direction of glutamate oxidation, and that leucine may act as an endogenous activator of GDH in brain in vivo.
Manipulating Kv4.2 identifies a specific component of hippocampal pyramidal neuron A‐current that depends upon Kv4.2 expression
Authors: Lauver Aaron , Yuan Li‐Lian , Jeromin Andreas , Nadin Brian M. , Rodríguez José J. , Davies Heather A. , Stewart Michael G. , Wu Gang‐Yi , Pfaffinger Paul J.
Published: October 2006

The somatodendritic A‐current, ISA, in hippocampal CA1 pyramidal neurons regulates the processing of synaptic inputs and the amplitude of back propagating action potentials into the dendritic tree, as well as the action potential firing properties at the soma. In this study, we have used RNA interference and over‐expression to show that expression of the Kv4.2 gene specifically regulates the ISAcomponent of A‐current in these neurons. In dissociated hippocampal pyramidal neuron cultures, or organotypic cultured CA1 pyramidal neurons, the expression level of Kv4.2 is such that the ISAchannels are maintained in the population at a peak conductance of approximately 950 pS/pF. Suppression of Kv4.2 transcripts in hippocampal pyramidal neurons using an RNA interference vector suppresses ISAcurrent by 60% in 2 days, similar to the effect of expressing dominant‐negative Kv4 channel constructs. Increasing the expression of Kv4.2 in these neurons increases the level of ISAto 170% of the normal set point without altering the biophysical properties. Our results establish a specific role for native Kv4.2 transcripts in forming and maintaining ISAcurrent at characteristic levels in hippocampal pyramidal neurons.
Caribbean Transnational Return Migrants as Agents of Change
Authors: Conway Dennis , Potter Robert B.
Published: October 2006

This article challenges several of the firmly held convictions drawn from extant research on return migration to the Caribbean. For many contemporary small island societies undergoing rapid change and transformation, modernization and integration into the wider global economy, today's younger and more youthful return migrants are no longer an ineffective demographic cohort. Despite their numerically small size, many are demonstrating they can be influential “agents of change.” No longer merely returning retirees, they are more diverse, in terms of age, life‐course transitions, class and gendered social positions, family networks, and migration histories. Multiple identities are the rule, rather than the exception, as returnees of different ages choose to live, work (and play) in island society, to give something back to the island home of their parents or of their youth. Many embrace transnational strategies to live in and between two worlds, or more if their family network's reach is multilocal.
Recovery of Equine Encephalomyelitis Virus (Western Type) from Chicken Mites
Authors: Sulkin S. Edward
Published: October 2006

The Western type of equine encephalomyelitis virus has been isolated from chicken mites (
Dermanyssus gallinae
) in nature during an outbreak of the equine disease in the Southwest.
Method for the Detection of Indole
Authors: Jacobs Morris B. , Pincus Sol
Published: October 2006

A simple and sensitive method for the detection of indole in cultures, urine, sewage, etc., is presented. The indole is extracted with chloroform and is then treated with a modified Ehrlich reagent. The possibility of use for the detection of water pollution is indicated.
Control and Evaluation of Blood Serum Assays for Penicillin
Authors: Chandler Velma L. , Price Clifford W. , Randall William A.
Published: October 2006

A method for adequate control and evaluation of blood serum assays for penicillin is given and the effectiveness of the method for controlling the several types of penicillin is shown.
Penicillin Blood-Level Determinations With a
Streptococcus dysgalactiae
Resistant to Normal Blood Inhibitors
Authors: Kakavas J. C. , Scott E. G.
Published: October 2006

A strain of
Str. dysgalactiae
was found to be an effective test organism for penicillin blood-level determinations. This organism, although inhibited by penicillin in concentrations of 0.006-0.008 unit/ml., is resistant to the natural inhibiting substances of blood sera. The latter characteristic is very significant, since the test organisms (
Str. pyogenes
C-203 and
B. subtilis
) that are now employed for penicillin assay of body fluids are inhibited by a large percentage of human sera.

The method described can detect penicillin blood levels in concentration of 0.016 unit/ml. of blood sera. Since blood levels above 0.03 unit/ml. are considered to be therapeutically effective, this method of assay is adequately sensitive for routine clinical application.
Uncoupling Agents Distinguish Between the Effects of Metabolic Inhibitors and Transport Inhibitors
Authors: Weiner Michael W.
Published: October 2006

In studies with toad bladders, the uncoupling agent 2,4-dinitrophenol (DNP) reversed the inhibition of CO
2
production produced by direct inhibition of transport. In contrast, DNP did not reverse the inhibition of CO
2
production brought about by metabolic inhibitors. Therefore, the response to DNP distinguished between inhibition of transport and metabolism; this approach may be useful for the investigation of factors that regulate active transport.
Carbohydrate Deficiency of the Factor VIII/von Willebrand Factor Protein in von Willebrand's Disease Variants
Authors: Gralnick Harvey R. , Coller Barry S. , Sultan Yvette
Published: October 2006

Study of the normal human factor VIII/von Willebrand factor reveals a macromolecular glycoprotein composed of apparently identical subunits. This purified glycoprotein has procoagulant, antigen, and von Willebrand factor activities. In three patients with a variant of the von Willebrand's disease syndrome, their factor VIII/von Willebrand factor protein was present in normal amounts and had normal procoagulant and antigen activities; however, this protein was deficient in both carbohydrate and von Willebrand factor activity. The carbohydrate portion of the factor VIII/von Willebrand factor glycoprotein is of major importance in its interactions with platelets or the blood vessel wall, or both.
Nuclear Transcripts of Mouse Heavy Chain Immunoglobulin Genes Contain Only the Expressed Class of C-Region Sequences
Authors: Marcu K. B. , Schibler U. , Perry R. P.
Published: October 2006

In plasmacytoma cells producing IgG, IgA, or IgM immunoglobulin heavy chains, the large precursors of the heavy chain messenger RNA's contain nucleotide sequences that specify only the expressed class of constant region. This indicates that the switch from one class of heavy chain to another during B cell ontogeny does not occur by altered processing of a complex gene transcript.
Civil Liberties of Scientists
Authors:   Special Committee of the AAAS
Published: October 2006

On December 30, 1947 the AAAS Council passed a resolution instructing the President of the Association to appoint a Special Committee on Civil Liberties for Scientists. Maurice B. Visscher was named chairman, and with Philip Bard, Robert E. Cushman, Richard L. Meier, and James R. Newmen as members, and Walter Gellhorn as consultant, the Committee completed its investigations and submitted a 77-page report of findings and recommendations in December 1948. The full text was referred to the Council, which voted by an overwhelming majority to publicize the findings, and it is planned ultimately to make the complete report available at cost to those who want access to it. Announcement will be made in
Science
when Maurice B. Visscher and E. C. Stakman have concluded editorial revisions and the report is ready for distribution. Meanwhile, by vote of the Executive Committee at its meeting July 7, the conclusions and recommendations are published herewith.
Mapping of Functional Neural Pathways by Autoradiographic Survey of Local Metabolic Rate with [
14
C]Deoxyglucose
Authors: Kennedy C. , Des Rosiers M. H. , Jehle J. W. , Reivich M. , Sharpe F. , Sokoloff L.
Published: October 2006

If sufficient time has elapsed following an intravenous pulse of [
14
C]deoxyglucose, the carbon-14 contents of the tissues of the central nervous system represent mainly the accumulated phosphorylated derivative of [
14
C]deoxyglucose and reflect the rates of glucose consumption of the tissues. Altered functional activity alters metabolic activity and the uptake of [
14
C]deoxyglucose in the tissues. By autoradiographic survey of sections of the central nervous system it is then possible to map all the regions with altered functional and metabolic activities in response to experimentally induced changes in functional state.
Phototransduction in
Aplysia
Neurons: Calcium Release from Pigmented Granules Is Essential
Authors: Brown A. M. , Baur P. S. , Tuley F. H.
Published: October 2006

Increased free intracellular calcium mediates increased membrane potassium conductance in illuminated
Aplysia
giant neurons. The calcium source was examined by microprobe analysis of cytoplasmic pigmented granules. Illumination markedly depleted granules of calcium and altered them structurally. Release of calcium from granules is essential for phototransduction.
Antipsychotic Drugs: Direct Correlation Between Clinical Potency and Presynaptic Action on Dopamine Neurons
Authors: Seeman P. , Lee T.
Published: October 2006

Neuroleptic (antipsychotic) drugs inhibited the electrically stimulated release of [3H]dopamine from rat striatal slices. The concentrations for 50 percent inhibition (ranging from 11.5 nanomolar for spiroperidol to 800 nanomolar for thioridazine) correlated closely with the average daily dosages of 25 neuroleptic drugs used clinically for schizophrenia. The correlation includes butyrophenones, phenothiazines, reserpine, pimozide, clozapine, and (+)-butaclamol. Clinically inactive isomers [trans-thiothixene,trans-flupenthixol, and (-)-butaclamol] required 20 to 1000 times higher concentrations than the active isomers to inhibit release. Compared to the inhibition of [3H]dopamine release, much higher neuroleptic concentrations were needed to inhibit the electrically stimulated release of other neurotransmitters—[3H]acetylcholine, [3H]GABA (γ-aminobutyric acid). The neuroleptic drugs may block the presynaptic coupling between impulse and neurosecretion.
Water in SNC Meteorites: Evidence for a Martian Hydrosphere
Authors: Karlsson Haraldur R. , Clayton Robert N. , Gibson Everett K. , Mayeda Toshiko K.
Published: October 2006

The Shergotty-Nakhla-Chassigny (SNC) meteorites, purportedly of martian origin, contain 0.04 to 0.4 percent water by weight. Oxygen isotopic analysis can be used to determine whether this water is extraterrestrial or terrestrial. Such analysis reveals that a portion of the water is extraterrestrial and furthermore was not in oxygen isotopic equilibrium with the host rock. Lack of equilibrium between water and host rock implies that the lithosphere and hydrosphere of the SNC parent body formed two distinct oxygen isotopic reservoirs. If Mars was the parent body, the maintenance of two distinct reservoirs may result from the absence of plate tectonics on the planet.
Formaldehyde and Organic Molecule Production in Astrophysical Ices at Cryogenic Temperatures
Authors: Schutte W. A. , Allamandola L. J. , Sandford S. A.
Published: October 2006

Thermally promoted formaldehyde (H
2
CO) reactions in cryogenic ices have been studied to test their importance as a source of organic molecules in comets and interstellar ices. Ices containing H
2
CO, H
2
O, CH
3
OH, CO, and NH
3
were investigated by using infrared spectroscopy. Small traces of NH
3
(NH
3
/H
2
CO ≥ 0.005) are sufficient to convert significant fractions (≥ 40%) of the H
2
CO into more complex organics. However, H
2
CO reactions do not proceed without NH
3
. Spectral evidence for reaction onset appeared between 40 and 80 kelvin, depending on the ice. Five distinct products were formed. These principally consist of polyoxymethylene and related derivatives. Polyoxymethylene itself was not made in significant amounts in cometary analogs. These products differ from those produced by ultraviolet and particle irradiation. The nature and relative amounts of the products depend on the initial composition, making these materials excellent tracers of a comet's history. About 3% of the organics in p-Halley's coma could have been produced by thermal H
2
CO reactions.
Growth, Behavior, and Brain Catecholamines in Lead-Exposed Neonatal Rats: A Reappraisal
Authors: Golter Marianne , Michaelson I. Arthur
Published: October 2006

Daily oral administration of lead to newborn rats has no adverse effect on their body growth. Lead-treated rats were more active than age-matched controls. Endogenous levels of brain dopamine were unchanged, whereas norepinephrine was increased, suggesting a possible relationship between lead exposure during earliest developmental periods, increased motor activity, and brain norepinephrine, and not brain dopamine as previously postulated.
Pressure-Induced Depolymerization of Brain Microtubules in Vitro
Authors: Salmon E. D.
Published: October 2006

Microtubules, assembled in vitro from tubulin extracted from rabbit brain, were subjected to changes in hydrostatic pressure (200 to 10,000 pounds per square inch) and temperature (37° to 0°C). Increased pressure, like cooling, reversibly depolymerizes microtubules, as measured by changes in either turbidity, birefringence, or the number of microtubules seen in electron micrographs. The characteristic response of brain microtubules in vitro to pressure is similar to that of mitotic spindle microtubules in vivo.
Cross-cultural differences in simple taste preferences
Authors: Moskowitz HW , Kumaraiah V , Sharma KN , Jacobs HL , Sharma SD
Published: October 2006

A population of Indian laborers who show high preferences for sour and bitter tastes has been studied. Their judgments of taste intensity and pleasantness of sweet and salty stimuli are in accord with European population estimates, which suggests that dietary history may alter preferences for simple taste stimuli without affecting the gustatory system.
Antimitotic Activity of the Potent Tumor Inhibitor Maytansine
Authors: Remillard Stephen , Rebhun Lionel I. , Howie Gary A. , Kupchan S. Morris
Published: October 2006

Maytansine, at 6 × 10
-8
M
, irreversibly inhibits cell division in eggs of sea urchins and clams. It causes the disappearance of a mitotic apparatus or prevents one from forming if added at early stages. Maytansine does not affect formation of the mitotic organizing center but does inhibit in vitro polymerization of tubulin. Maytansine and vincristine inhibit in vitro polymerization of tubulin at about the same concentrations, but vincristine is about 100 times less effective as an inhibitor of cleavage in marine eggs.
Vitamin A: Not Required for Adrenal Steroidogenesis in Rats
Authors: Gruber Kenneth A. , O'Brien Laura V. , Gerstner Robert
Published: October 2006

Previous work supporting the vitamin A dependency of adrenal function in rats neglected to take into account a secondary effect of the deficiency, a decrease in hepatic ascorbic acid biosynthesis. Vitamin A-depleted rats maintained on a diet free of ascorbate had a decrease in the activity of adrenal 3 β-hydroxysteroid dehydrogenase, and extensive adrenocortical degeneration. The use of an ascorbate supplement prevented the symptoms. The results suggest that previous evidence for direct involvement of vitamin A in steroidogenesis may have been due to the production of a secondary deficiency, a chronic scorbutic condition.
Opsin Structure Probed by Raman Spectroscopy of Photoreceptor Membranes
Authors: Rothschild Kenneth J. , Andrew James R. , De Grip Willem J. , Stanley H. Eugene
Published: October 2006

The first nonresonance Raman spectra of photoreceptor membranes are presented. Information about the membrane protein, opsin, and the membrane phospholipids can be deduced. Opsin appears to contain α-helical structure but little β structure. The tyrosine residues are predominantly hydrogen bonded, and disulfide bonds, if they are present, are not in the normal gauche-gauche configuration.
Human Y-Chromosome-Specific Reiterated DNA
Authors: Kunkel Louis M. , Smith Kirby D. , Boyer Samuel H.
Published: October 2006

Radiolabeled reiterated DNA specific for the human Y chromosome has been obtained by extensive reassociations between [
3
H]DNA prepared from men and excess DNA from women. These highly purified labeled sequences reassociate only with DNA from individuals with a Y chromosome. The percentage of Y-chromosome-specific DNA isolated from individuals with differing numbers of Y chromosomes is a function of the number of Y chromosomes present. The purified Y-chromosome-specific sequences may represent between 7 and 11 percent of the human Y chromosome.
Sex Differences in Cognition: A Function of Maturation Rate?
Authors: Waber Deborah P.
Published: October 2006

Regardless of sex, early maturing adolescents performed better on tests of verbal than spatial abilities, the late maturing ones showed the opposite pattern. Those maturing late were more lateralized for speech than those maturing early. Sex differences in mental abilities, it is argued, reflect differences in the organization of cortical function that are related to differential rates of physical maturation.
Ultrastructure of the Auditory Regions in the Inner Ear of the Lake Whitefish
Authors: Popper Arthur N.
Published: October 2006

Hair cell polarization patterns were investigated on the sensory macule of the sacculus and lagena of the lake whitefish. The saccular hair cells are divided into four groups, with all of the cells within a group having the same orientation. Saccular orientations are anterior, posterior, dorsal, and ventral with respect to the axis of the animal. Two groups, one dorsal and one ventral, are found on the lagena. The saccular orientations are significantly different from those in tetrapods. Since this organ appears to have different functions in fish and tetrapods it is likely that the orientation patterns in fish are adapted to some aspect of audition—perhaps directional localization of sound.
Coturnix
Quail as a Laboratory Research Animal
Authors: Padgett Carol Ann , Ivey William D.
Published: October 2006

The
Coturnix
quail is recommended to interested investigators, especially to embryologists and physiologists, for use in research because of its hardiness, ease of handling, precociousness, and great laying ability.
Low-Level Irradiation and Threshold Shift in the Visual Receptor
Authors: Dawson William W. , Smith James C.
Published: October 2006

Customary methods of stimulating and recording were used to examine threshold shifts of the single visual receptor in the lateral eye of
Limulus
in response to low-level x-irradiation. Marked visual sensitization was found and was most pronounced at the lowest dosage levels (1 to 25 r). Complete light adaptation apparently cancelled the effects of the irradiation.
Ablation of Transplanted HTLV-I Tax-Transformed Tumors in Mice by Antisense Inhibition of NF-κB
Authors: Kitajima Isao , Shinohara Toshiya , Bilakovics James , Brown David A. , Xu Xiao , Nerenberg Michael
Published: October 2006

Mice transgenic for the human T cell leukemia virus (HTLV-I) Tax gene develop fibroblastic tumors that express NF-κB-inducible early genes. In vitro inhibition of NF-κB expression by antisense oligodeoxynucleotides (ODNs) inhibited growth of these culture-adapted Tax-transformed fibroblasts as well as an HTLV-I-transformed human lymphocyte line. In contrast, antisense inhibition of Tax itself had no apparent effect on cell growth. Mice treated with antisense to NF-κB ODNs showed rapid regression of transplanted fibrosarcomas. This suggests that NF-κB expression may be necessary for the maintenance of the malignant phenotype and provides a therapeutic approach for HTLV-I-associated disease.
Sustained Swimming Speeds of Dolphins
Authors: Johannessen Carl L. , Harder James A.
Published: October 2006

Observations of four large groups of dolphins suggest that they are able to swim at a sustained speed of 14 to 18 knots. The blackfish are able to maintain speeds of about 22 knots, and one killer whale seemed able to swim somewhat faster. This implies that the apparent coefficient of surface friction remains approximately constant for dolphins from 6 to 22 ft long, as is the case for rigid bodies.
Estimation of Total Body Fat from Potassium-40 Content
Authors: Forbes Gilbert B. , Gallup James , Hursh John B.
Published: October 2006

On the assumption that the potassium content of the lean body mass is constant, it should be possible to estimate fat content in living man from a measurement of potassium-40 activity in the whole-body scintillation counter. A series of such measurements on children and young adults shows good correlations with skin-fold thickness and weight/height ratio as indices of fatness.
Effect of Deuterium Substitution in Sympathomimetic Amines on Adrenergic Responses
Authors: Belleau B. , Burba J. , Pindell M. , Reiffenstein J.
Published: October 2006

It was discovered that replacement of the α-hydrogens of tyramine and tryptamine by deuterium produces a marked intensification of the blood pressure effects and nictitating membrane contraction normally produced by these amines. The results are interpreted on the basis of kinetic isotope effects at the level of monoamine oxidase and clearly establish the importance of this enzyme in the limitation of responses when tyramine and tryptamine are involved. The observed deuterium isotope effects with α,α-bisdeuterotyramine (α,α-D
2
-tyramine) have been reproduced with only one of the optical isomers of monodeuterotyramine. This establishes that the enzyme displays a high degree of optical specificity. The use of
l
-bisdeuteronorepinephrine revealed that norepinephrine cannot be attacked by the enzyme at the effector cell level.
Production of Polydipsia in Normal Rats by an Intermittent Food Schedule
Authors: Falk John L.
Published: October 2006

Marked polydipsia was produced in all animals trained to press a bar for food pellets on a 1-minute variable-interval schedule. It is suggested that since this feeding arrangement produces a sustained, high fluid intake in the normal, unrestrained animal, it might serve as a useful tool in the study of renal function.
Facultative Heterotrophy in Some Chlorococcacean Algae
Authors: Parker Bruce C. , Bold Harold C. , Deason Temd R.
Published: October 2006

All known species of the genera
Bracteacoccus
,
Spongiochloris
, and
Dictyochloris
, and some of the species of
Neochloris
and
Spongiococcum
are capable of growing heterotrophically in darkness in a glucose-salts medium. In contrast, all known species of
Chlorococcum
are obligate photoautotrophs. Possible relationships between these results and certain morphological characteristics are discussed.
Ether-Induced Retrograde Amnesia for One-Trial Conditioning in Mice
Authors: Abt John P. , Essman Walter B. , Jarvik Murray E.
Published: October 2006

Mice were tested in a situation permitting them to step readily from a small, restrictive platform to a larger one. Conditioned avoidance was established by a single training trial when animals received a shock by stepping from one platform to another. At various intervals after the single punishing shock, subjects were anesthetized with diethyl ether. Interference with retention, tested 1 day later, was shown for intervals up to 24 minutes, at which time ether no longer appeared to influence the subsequent response.
New Arrangement of Interrenal and Chromaffin Tissues of Teleost Fishes
Authors: Nandi Jean
Published: October 2006

An unusual morphologic arrangement of interrenal and chromaffin tissues has been observed in two families of teleost fishes. In most teleosts in which these cell types occur together in association with the postcardinal veins and their branches, the chromaffin cells are located between the lumen of the vein and the interrenal cells. This typical relationship is reversed in some of the Labridae and Scaridae.
A Function for Tissue Mast Cells
Authors: Draper Laurence R. , Smith Douglas E.
Published: October 2006

Experimental elimination of mast cells from the peritoneal tissues of the rat by distilled water treatment inhibited the increase of vascular permeability which normally follows a passively induced antigen-antibody reaction in peritoneal tissue. Thus mast cells may contribute to the initiation of inflammation which follows antigen-antibody reactions.
Glucose-6-Phosphate Dehydrogenase and Detoxification of Hydrogen Peroxide in Human Erythrocytes
Authors: Cohen Gerald , Hochstein Paul
Published: October 2006

Human erythrocytes with deficient glucose-6-phosphate dehydrogenase levels are unable to maintain their levels of reduced glutathione in the presence of low-level, steady-state concentrations of hydrogen peroxide. This finding has bearing on the biochemical mechanisms of drug-induced hemolytic anemia.
Evidence of a Role for Heterotrimeric GTP-Binding Proteins in Endosome Fusion
Authors: Colombo Maria I. , Mayorga Luis S. , Casey Patrick J. , Stahl Philip D.
Published: October 2006

Guanosine triphosphate (GTP)-binding proteins are required for intracellular vesicular transport. Mastoparan is a peptide component of wasp venom that increases nucleotide exchange in some classes of Gα subunits of regulatory heterotrimeric GTP-binding proteins (G proteins). Mastoparan and other compounds that increase nucleotide exchange by G proteins inhibited endosome fusion in vitro and reversed the effects of guanosine 5′-
O
-(3-thiotriphosphate) (GTP-γ-S), a nonhydrolyzable GTP analog. Addition of βγ subunits of G proteins to the fusion assay antagonized the stimulatory effect of GTP-γ-S, confirming the participation of G proteins. These results indicate that GTP-binding proteins are required for endosome fusion and in particular that a G protein is involved. Given the function of G proteins in signal transduction, these findings may provide insight into the mechanism by which endosomal vesicles become competent for fusion after their formation at the cell surface.
The Human Y Chromosome: Overlapping DNA Clones Spanning the Euchromatic Region
Authors: Foote Simon , Vollrath Douglas , Hilton Adrienne , Page David C.
Published: October 2006

The human Y chromosome was physically mapped by assembling 196 recombinant DNA clones, each containing a segment of the chromosome, into a single overlapping array. This array included more than 98 percent of the euchromatic portion of the Y chromosome. First, a library of yeast artificial chromosome (YAC) clones was prepared from the genomic DNA of a human XYYYY male. The library was screened to identify clones containing 160 sequence-tagged sites and the map was then constructed from this information. In all, 207 Y-chromosomal DNA loci were assigned to 127 ordered intervals on the basis of their presence or absence in the YAC's, yielding ordered landmarks at an average spacing of 220 kilobases across the euchromatic region. The map reveals that Y-chromosomal genes are scattered among a patchwork of X-homologous, Y-specific repetitive, and single-copy DNA sequences. This map of overlapping clones and ordered, densely spaced markers should accelerate studies of the chromosome.
Reproductive Cycle of the California Leaf-Nosed Bat,
Macrotus californicus
Authors: Bradshaw Gordon VR.
Published: October 2006

Spermatogenesis is limited to summer and fall, and females are inseminated during the fall concurrent with ovulation and fertilization. While most of the embryonic development is deferred until March, there is slow growth of embryo and placenta during the winter. This sequence is termed "delayed development." Birth is in June, and the young bats are able to join the forage flights by August.
Secretion of Benzaldehyde and Hydrogen Cyanide by the Millipede
Pachydesmus crassicutis
(Wood))
Authors: Blum Murray S. , Woodring J. Porter
Published: October 2006

The millipede
Pachydesmus crassicutis
(Wood) secretes a mixture of benzaldehyde and hydrogen cyanide when it is disturbed. These compounds are secreted through paired glands located on 11 of the notal projections of adult millipedes. Experiments with the imported fire ant demonstrate that these natural products serve a defensive function.
Semilogarithmic Plots of Data Which Reflect a Continuum of Exponential Processes
Authors: Van Liew Hugh D.
Published: October 2006

A set of experimental data which describes a curve on semilogarithmic paper may reflect the operation of a continuum of exponential processes, particularly in biological systems where variability is expected. The "backward projection" technique for graphic separation of exponential processes is most misleading when applied to systems in which the processes are distributed so that the standard deviation of halftimes is large compared to the mean halftime.
Low-Energy Electron Diffraction
Authors: MacRae A. U.
Published: October 2006

This discussion of a few preliminary experiments with nickel points out some of the potential uses of low energy electron diffraction in improving our understanding of many types of surface phenomena. The first, and probably the most basic use, is in the study of clean surfaces. As illustrated in this article, the physical properties of the surface layer of atoms may be totally unlike those in the bulk of the crystal. It is necessary to understand such phenomena before a thorough understanding of chemical effects on surfaces can be achieved. The adsorption of gases, oxidation and corrosion, and the formation of epitaxial layers can all be studied in great detail by low energy electron diffraction.
Observation of Internal Structures of Teeth by Ultrasonography
Authors: Baum Gilbert , Greenwood Ivan , Slawski Stan , Smirnow Robert
Published: October 2006

Preliminary experiments with high-resolution intensity-modulated ultrasonography techniques developed for ophthalmological diagnosis have demonstrated that at a frequency of 15 megacycles per second some internal structures can be seen in vital teeth. A relationship between time, tooth vitality, and ultrasonic viewing was observed.
Polygonal Fracture and Fold Systems in the Salt Crust, Great Salt Lake Desert, Utah
Authors: Christiansen F. W.
Published: October 2006

Small folds and fractures (thrusts) up to 50 feet apart that have produced polygonal patterns in the Bonneville salt crust, western Utah, are believed to be caused by the annual expansion of the salt crust due to the growth of salt crystals within the salt layer plus the effect of increased summer temperature. It is suggested that these strain systems are caused by positive (compressional) isotropic planar stresses developed within the salt layers of the salt crust.
Xenon Tetrafluoride: Heat of Formation
Authors: Gunn Stuart R. , Williamson Stanley M.
Published: October 2006

Calorimetric measurements of the heat of reaction of xenon tetrafluoride with aqueous iodide solution give -60 kilocalories per mole for the standard heat of formation, or an average thermochemical bond energy of about 31 kilocalories.
Cadmium: Uptake by Vegetables from Superphosphate in Soil
Authors: Schroeder Henry A. , Balassa Joseph J.
Published: October 2006

Phosphates in fertilizers contain cadmium. When vegetables usually devoid of cadmium were grown in soil heavily fertilized with 20 percent superphosphate, they absorbed it. Vegetables normally containing cadmium absorbed larger quantities in the presence of superphosphate and little or none in its absence. The superphosphate showed 7.25 parts of cadmium per million. Five grains usually containing cadmium were grown in unfertilized soil poor in this element; four did not absorb it. Phosphate fertilizers may be a source of the cadmium in some vegetable foods.
Varying Sensitivity of C57BL/Crg1 Mice to Grouping
Authors: Thiessen D. D.
Published: October 2006

Mice responded differentially to increases in population size, depending on their prior experience. Compared to animals grouped prior to an increase in population size, animals housed as isolates responded to grouping with more fighting, a greater diminuation of testis weight, and a higher level of locomotor activity. They also had lower testis weight and higher locomotor activity than individually housed, nongrouped controls.
Interleukin-6 and Its Receptor: A Paradigm for Cytokines
Authors: Kishimoto Tadamitsu , Akira Shizuo , Taga Tetsuya
Published: October 2006

Many cytokines and cytokine receptors involved in the regulation of hematopoiesis, immune responses, and inflammation have been identified and characterized at the molecular level. Several characteristic features of cytokines, such as pleiotropy and redundancy, are now more clearly understood on the basis of their molecular structures. Accumulating evidence has demonstrated an intimate link between cytokines and various diseases such as allergy, autoimmune diseases, and cancer. The pathogenesis of these diseases and therapies to treat them will be discussed based on insights derived from cytokine research.
The Economics of Health Care in Japan
Authors: Ikegami Naoki
Published: October 2006

Japan's health care system balances universal coverage at reasonable cost. The government has taken on the responsibility of acting as insurer and subsidizing health care spending for the employees of small enterprises and the self-employed. Despite the fee-for-service form of payment, costs have been contained by the use of a nationally uniform fee schedule that is mandatory for all providers. However, the increasingly affluent and aging population is making new demands on the system that can only be met by a major restructuring.
Reticuloendothelial Function and the Immune Response
Authors: Wooles W. R. , Di Luzio N. R.
Published: October 2006

Hyperphagocytic activity of the reticuloendothelial system induced in mice by the injection of glucan is associated with a significant increase in the primary and secondary immune responsiveness of these animals to sheep erythrocytes. Conversely, the administration of an agent which reduces endothelial phagocytosis is associated with significant depression of both primary and secondary immune responsiveness.