bluuebunny/crossref_metadata_2025 huggingface dataset:
Forskolin Potentiates the Stimulation of Rat Striatal Adenylate Cyclase Mediated by D‐1 Dopamine Receptors, Guanine Nucleotides, and Sodium Fluoride
Authors: Battaglia George , Norman Andrew B. , Hess Ellen J. , Creese Ian
Published: October 2006

Abstract: We report here that forskolin acts in a synergistic manner with dopaminergic agonists, guanine nucleotides, or sodium fluoride to potentiate the stimulation of rat striatal adenylate cyclase mediated by these reagents. In the presence of 100 μM GTP, 100 μM guanyl‐5′‐yl imidodiphosphate [Gpp(NH)p], or 10 mM NaF, there is a greater than additive increase in forskolin‐stimulated enzyme activity as well as a concomitant decrease (two‐to fourfold) in the EC50 value for forskotin stimulation of striatal enzyme activity. In the presence of various concentrations of forskolin (10 nM–100 μM), the stimulation of adenylate cyclase elicited by GTP, Gpp(NH)p, and NaF is potentiated 194–1,825%, 122–1,141%, and 208–938%, respectively, compared with the stimulation by these agents above basal activity in the absence of forskolin. With respect to 3,4‐dihydroxyphenylethylamine (dopamine) receptor‐mediated stimulation of striatal enzyme activity, the stimulation of enzyme activity by dopaminergic agonists, in the absence or presence of forskolin, was GTP‐dependent and could be antagonized by the selective D‐1 antagonist SCH23390 (100 nM), indicating that these effects are mediated by D‐1 dopamine receptors. In the presence of 100 μM GTP, forskolin at various concentrations markedly potentiates the stimulation elicited by submaximal as well as a maximally effective concentrations of dopamine (100 μM) and SKF38393 (1 μM). At higher concentrations of forskolin (10–100 μM) the stimulation elicited by the partial agonist SKF38393 is comparable to that of the full agonist dopamine. In contrast to the effects observed with GTP, in the presence of 100 μM Gpp(NH)p there was no significant stimulation by dopaminergic agonists in the absence or presence of forskolin. These data demonstrate that in rat striatal homogenates forskolin can stimulate adenylate cyclase by (1) its direct action at the catalytic subunit, (2) by potentiating the stimulation elicited by the guanine nucleotide regulatory protein (Ns), and (3) by markedly potentiating the stimulation elicited by partial and full dopaminergic agonists acting at D‐1 dopamine receptors.
Changes in Levels of Purine and Pyrimidine Nucleotides During Acute Hypoxia and Recovery in Neonatal Rat Brain
Authors: Hisanaga Kinya , Onodera Hiroshi , Kogure Kyuya
Published: October 2006

AbstractNeonatal rat brains were examined for changes in levels of ATP, ADP, AMP, cyclic AMP, GTP, GDP, UTP, UDP, UMP, and CTP during exposure to 100% nitrogen for 20 min and subsequent recovery in air. During hypoxia, ATP, GTP, UTP, and CTP levels and the GTP/GDP ratio decreased to 38, 50, 26,21, and 21%, respectively, of control levels. No significant change in cyclic AMP level was observed. The decrease in the total uridine nucleotide pool during hypoxia was markedly greater (to 53% of control levels) than that in the total adenine nucleotide pool (to 92% of control levels). During recovery, ATP and GTP levels were rapidly and almost completely restored. On the other hand, CTP levels returned slowly to control values after a 2‐h recovery period. Restoration of the UTP level was slow and incomplete (87% of the control value even after a 3‐h recovery period). The GTP/GDP ratio also did not return to normal. These data suggest that hypoxic insult to the neonate may have an effect on the synthesis of nucleotidyl sugars, phospholipids, and proteins in the brain, resulting in significant problems with developmental processes of the brain. The present study also showed that the delayed restorations of the UTP level and the GTP/GDP ratio were not seen in the brains of adult rats subjected to acute severe hypoxic insult.
Glucose Transporter in Plasma Membranes of Cultured Neural Cells, as Characterized by Cytochalasin B Binding
Authors: Keller K. , Lange K. , Malkewitz J.
Published: October 2006

Abstract Identification of hexose transporter sites by cytochalasin B binding was conducted with a centrifugation assay. The determination of KD and Bmax values by LIGAND computer analysis provided binding data that are similar in primary astrocytes (238 nM and 14 pmol/mg protein) and neuroblastoma cells (179 nM and 13.6 pmol/mg protein). In contrast, only an insignificant number of transporter sites was detectable in C6 glioma cells, irrespective of whether membrane fractions were obtained by a two‐phase polymer system or by a latex phagocytosis technique yielding insideout plasma membranes. The latter membrane preparation was utilized to identify and quantitate the transporter molecules at the inner membrane surface of primary astrocytes, i.e., 160 nM (KD) and 5.8 pmol/mg protein (Bmax), respectively.
Stimulatory Effect of the D2 Antagonist Sulpiride on Glucose Utilization in Dopaminergic Regions of Rat Brain
Authors: Pizzolato Gilberto , Soncrant Timothy T. , Larson Denise M. , Rapoport Stanley I.
Published: October 2006

Local cerebral glucose utilization (LCGU) was measured, using the quantitative autoradiographic [14C]2‐deoxy‐d‐glucose method, in 56 brain regions of 3‐month‐old, awake Fischer‐344 rats, after intraperitoneal administration of sulpiride (SULP) 100 mg/kg. SULP, an “atypical” neuroleptic, is a selective antagonist of D2 dopamine receptors. LCGU was reduced in a few nondopaminergic regions at 1 h after drug administration. Thereafter, SULP progressively elevated LCGU in many other regions. At 3 h, LCGU was elevated in 23% of the regions examined, most of which are related to the CNS dopaminergic system (caudate‐putamen, nucleus accumbens, olfactory tubercle, lateral habenula, median eminence, paraventricular hypothalamic nucleus). Increases of LCGU were observed also in the suprachiasmatic nucleus, lateral geniculate, and inferior olive. These effects of SULP on LCGU differ from the effects of the “typical” neuroleptic haloperidol, which produces widespread decreases in LCGU in the rat brain. Selective actions on different subpopulations of dopamine receptors may explain the different effects of the two neuroleptics on brain metabolism, which correspond to their different clinical and behavioral actions.
Lead Enters Bovine Adrenal Medullary Cells Through Calcium Channels
Authors: Simons T. J. B. , Pocock G.
Published: October 2006

Abstract: Agents that stimulate secretion also accelerate the rate of Pb uptake into adrenal medullary cells. For example, when cells are suspended in a medium containing 5 μM Pb2+, depolarization by 77 mM K increases the rate of Pb uptake from 12 ± 1 to 47 ± 5 μmol/(L cells × min). K‐induced Pb uptake has an apparent Km for Pb2+ of 2.6 μM, and is antagonized by Ca2+ with a K0.5 of 1.4 mM. The Ca channel blocker D‐600 inhibits Pb entry with a K0.5 of 0.4 μM. Pb uptake is also stimulated by the Ca channel agonist BAY K 8644. These observations suggest that Pb passes through Ca channels. The permeability of the channels to Pb appears to be at least 10 times the permeability to Ca.
Role of Thyroid Hormone and Nerve Growth Factor in the Development of Choline Acetyltransferase and Other Cell‐Specific Marker Enzymes in the Basal Forebrain of the Rat
Authors: Patel Ambrish J. , Hayashi Masao , Hunt Anthony
Published: October 2006

The effects of treatment with l‐thyroxine (subcu‐taneously 0.3 μg/g body weight daily from birth, i.e., day 1) and 2.5S nerve growth factor (NGF; intraventricularly 2 μg on 1, 3, 5, 7, and 9 postnatal days), separately and together, were studied on the biochemical development of different cell types in the basal forebrain of 10‐day‐old rats. The development of cholinergic, γ‐aminobutyric acid‐ergic (GABAergic), and glutamatergic neurons was monitored respectively in terms of choline acetyltransferase (ChAT), glutamate decarboxylase (GAD), and glutaminase activities, whereas glutamine synthetase (GS) and 2′,3′‐cyclic nu‐cleotide‐3′‐phosphohydrolase (CNPase) activities were used to judge the maturation of astroglial and oligodendroglial cells. Treatment with either thyroid hormone or NGF from birth significantly increased the expression of ChAT activity in the basal forebrain of neonatal rats. When both agents were administered to the same animal, in agreement with our earlier in vitro findings, the stimulation in ChAT activity was much greater than the sum of the individual effects. In hypothyroid rats, significant effects of NGF at the low doses used were not detectable, although the increase of ChAT activity induced by thyroxine was potentiated by NGF in these animals. Under the present experimental conditions neither thyroxine nor NGF treatment had an appreciable effect on the activities of glutaminase, GS, and lactate dehydrogenase. However, the administration of thyroxine markedly increased CNPase activity in normal rats, whereas in hypothyroid rats the effect on both CNPase and GAD was also significant. Similar elevations in CNPase and GAD activities were not observed after NGF treatment, suggesting that the effect of NGF was specific to the cholinergic cells. The observations provide further support for our proposal that subcortical cholinergic neurons are subject to regulation by an interaction between thyroid hormone and local humoural factors such as NGF.
Ascorbate Modulates 5‐[3H]Hydroxytryptamine Binding to Central 5‐HT3 Sites in Bovine Frontal Cortex
Authors: Todd Richard D. , Bauer Paul A.
Published: October 2006

Abstract: Ascorbate is present in millimolar concentrations in mammalian brain and can be released from cellular stores by membrane depolarization. We report here that physiologically relevant concentrations of ascorbate modulate 5‐[3H]hydroxytryptamine ([3H]5‐HT) binding to bovine frontal cortex membranes. Under conditions where [3H]5‐HT binding is reversible and saturable, ascorbate causes a concentration‐dependent increase in the affinity of [3H]5‐HT for central 5‐HT3 binding sites. At pH 7.4, increasing ascorbate from 0 to 5.7 mM changes the equilibrium affinity constant (KD) of binding to 5‐HT3 sites from 125 nM to 30 nM, without affecting binding site number. These ascorbate‐induced effects are pH dependent. At pH 7.1 binding to central 5‐HT3 sites is essentially eliminated in the presence of ascorbate. These studies suggest that ascorbate and hydrogen ion concentration interactions may modulate serotonergic function.
Effects of Picrotoxin Treatment on GABAA Receptor Supramolecular Complexes in Rat Brain
Authors: Ito Yoshihisa , Lim Dong Koo , Nabeshima Toshitaka , Ho Ing K.
Published: October 2006

Abstract The effects of acute and chronic administration of a subconvulsive dose of picrotoxin on t‐[35S]butylbieyclophosphorothionate ([35S]TBPS), [3H]muscimol, and [3H]flunitrazepam binding characteristics in various regions and on the convulsant potency of picrotoxin in Sprague‐Dawley rats were examined. Acute administration of a sub‐convulsive dose of picrotoxin (3 mg/kg, i. p.) significantly increased [35S]TBPS and [3H]muscimol binding in cerebellum (CB) with no change in frontal cortex (FC). In rats treated chronically with picrotoxin (3 mg/kg, i.p., daily for 10 days), the Bmax of [35S]TBPS binding site was significantly decreased in the FC., striatum (ST), and CB with no change in KD values. Neither [3H]muscimol binding in the FC and CB nor [3H]fiunitrazepam binding in the FC was affected in these rats. In addition, the potency of pentobarbital to inhibit [35S]TBPS binding in vitro was not altered following acute or chronic treatment of picrotoxin. Chronic administration of picrotoxin did not affect convulsive ED50 or LD50 of picrotoxin; however, it delayed the onset of convulsions and increased the time to death. These results suggest that treatment with picrotoxin at a subconvulsive dose for 10 days causes down‐regulation of [35S]TBPS binding sites and that this down‐regulation might be related, at least in part, to the decreased extent of convulsant potency of picrotoxin. In addition, the results indicate possible interaction between convulsant binding sites and GABAA receptor sites in the CB following picrotoxin treatment.
Content of Mitochondrial DNA and of Three Mitochondrial RNAs in Developing and Adult Rat Cerebellum
Authors: Renis M. , Cantatore P. , Polosa P. Loguercio , Fracasso F. , Gadaleta M. N.
Published: October 2006

Abstract: The content of DNA and of 16S rRNA and of two mRNAs, i.e., the mRNA for the cytochrome c oxidase subunit I and the mRNA for one subunit of the NADH dehydrogenase (ND4), in free (nonsynaptic) mitochondria of developing and adult rat cerebellum has been determined. During postnatal development, DNA content of free (nonsynaptic) mitochondria increases 10 times from 1 to 30 days of age whereas, in adult rats, it is about 60% compared to that found in 30‐day‐old rats. The total content of each RNA species studied also increases during development. However, when the content of each RNA is expressed per mtDNA molecule, rRNAs and mRNAs behave differently: 16S rRNA level does not change during development and it is not significantly different from that of the adult rat, whereas the level of mRNAs is higher during development than in the adult rat and changes with age. These results are discussed in light of mitochondrial biogenesis in rat cerebellum during development and of the regulation of the mitochondrial DNA transcription process.
Increase in Kynurenic Acid in Huntington's Disease Motor Cortex
Authors: Connick J. H. , Carlà V. , Moroni F. , Stone T. W.
Published: October 2006

Abstract: Huntington's disease is a neurological disorder characterised by a progressive chorea and dementia. Recent evidence has suggested that dysfunction involving endogenous excitatory amino acids may be important in the pathogenesis of this disease. Following the recent demonstration that kynurenic acid is present in the brain, we examined the levels in various areas of brain from patients who died with Huntington's disease and from age/sex‐matched controls. Blocks (100–500 mg) of cortex (Brodmann's areas 4 and 10) and caudate nucleus and globus pallidus (lateral and medial parts) were obtained from the Cambridge Brain Bank. The tissue was then processed for the extraction and analysis of kynurenic acid. Whereas no differences in the content of kynurenic acid were observed in the caudate nucleus, lateral or medial globus pallidus, or prefrontal cortex (area 10) between controls' brains and those from patients who died with Huntington's disease, there was a 94% (p < 0.01; n = 5) increase in the kynurenic acid content in the motor cortex (area 4) from Huntington's disease brains, relative to those of controls. Some time ago we suggested that a subtle change in the relative concentrations of quinolinic and kynurenic acids might be important in the pathogenesis of neurodegeneration. It is possible that the observation of raised kynurenic acid levels supports this supposition. Further work is now in progress to determine whether the change in kynurenic acid is a primary effect or a compensatory response to an increase in excitatory activity.
Molecular Interaction of S‐100 Proteins with Microtubule Proteins In Vitro
Authors: Donatq Rosario , Giambanco Ileana , Aisa Maria Cristina
Published: October 2006

Abstract: Several procedures were employed to examine the in vitro interaction between S‐100 proteins and microtubule proteins. Binding of S‐100 to τ factors was observed under all experimental conditions. S‐100 binding to microtubule‐associated protein 2 (MAP2) was best detected by exposing nitrocellulose‐immobilized MAP2 or MAPs to either 125I‐labeled S‐100 or biotinylated S‐100. S‐100 binding to tubulin was detected when the two protein fractions were first incubated with each other followed by exposure to the Afunctional cross‐linker disuccinimidylsuberate, and then separated by sodium dodecyl sulfate‐polyacrylamide gel [electrophoresis (SDS‐PAGE) and transfered onto nitrocellulose paper. By this procedure, complex formation between S‐100 and tubulin, as well as between S‐100 and a relatively low‐molecular‐weight MAP, was evidenced by immunoblotting using an anti‐S‐100 antiserum. Alternatively, complex formation between biotinylated S‐100 and either tubulin or MAPs was visualized by means of avidin‐peroxidase, after SDS‐PAGE of the complex mixtures and transfer of the separated proteins onto nitrocellulose. The interaction between S‐100 and tubulin was strictly Ca2+ dependent, and resistant to high concentrations of KC1, colchicine, or vinblastine.
Antidepressant Treatments, Including Sibutramine Hydrochloride and Electroconvulsive Shock, Decrease β1 but Not β2‐Adrenoceptors in Rat Cortex
Authors: Heal D. J. , Butler S. A. , Hurst E. M. , Buckett W. R.
Published: October 2006

Abstract: The β1 and β2‐adrenoceptor populations in rat cortex were individually quantified by labelling all of the receptors with [3H]dihydroalprenolol and displacing with iso‐prenaline (200 μM) or CGP 20712A (l‐{2‐[(3‐carbamoyl‐4‐hydroxy)phenoxy]ethylamino}‐3‐[4‐(l‐methyl‐4‐trifluoro‐methyl‐2‐imidazolyl)phenoxy]‐2‐propanol methanesul‐phonate; 100 nM) to define total β‐adrenoceptors and β1‐adrenoceptors, respectively. Binding parameters for β2‐adrenoceptors were calculated by the difference. Oral administration of the monoamine reuptake inhibitors sibutramine HC1 (3 mg/kg), amitriptyline (10 mg/kg), desipramine (10 mg/kg), or zimeldine (10 mg/kg) for 10 days decreased the total number of β‐adrenoceptors present in rat cortex. This effect was entirely due to a reduction in the number of β1‐adrenoceptors. Similarly, 10 days of treatment with the monoamine oxidase inhibitor tranylcypromine (10 mg/kg p.o.) or five electroconvulsive shocks (ECSs; 200 V, 2 s) spread over this period also down‐regulated β‐adrenoceptors by reducing the content of the βsubtype. By contrast, treatment with clenbuterol (5 mg/kg p.o.) for 10 days reduced the number of cortical β‐adrenoceptors by an effect on the β2‐adre‐noceptor population. The effects of short‐term treatment with these drugs were also investigated, and, using the doses shown above, the results of 3 days of administration or a single ECS were determined. Sibutramine HC1 and desipramine were alone in producing a reduction in number of β‐adrenoceptors after 3 days. Once again, this was exclusively due to a loss of β1‐adrenoceptors. Together, the results show that antidepressants with disparate pharmacological actions all down‐regulated β‐adrenoceptors through the neuronal β1‐adrenoceptor subtype. In addition, sibutramine HC1 and desipramine produced this attenuation very rapidly. However, clenbuterol treatment reduced the number of β2‐adrenoceptors, and its reported antidepressant activity is, therefore, unlikely to be mediated via this mechanism.
Adenosine Receptor Activation and the Regulation of Tyrosine Hydroxylase Activity in PC 12 and PC 18 Cells
Authors: Roskoski Robert , Roskoski Laura M.
Published: October 2006

Abstract: We compared the response of rat PC12 cells and a derivative PC 18 cell line to the effects of adenosine receptor agonists, antagonists, and adenine nucleotide metabolizing enzymes. We found that theophylline (an adenosine receptor antagonist), adenosine deaminase, and AMP deaminase all decreased basal cyclic AMP content and tyrosine hydroxylase activity in the PC12 cells, but not in PC18 cells. Both cell lines responded to the addition of 2‐chloroadenosine and 5′‐N‐ethylcarboxamidoadenosine, adenosine receptor agonists, by exhibiting an increase in tyrosine hydroxylase activity and cyclic AMP content. The latter finding indicates that both cell lines contained an adenosine receptor linked to adenylate cyclase. We found that the addition of dipyridamole, an inhibitor of adenosine uptake, produced an elevation of cyclic AMP and tyrosine hydroxylase activity in both cell lines. Deoxycoformycin, an inhibitor of adenosine deaminase, failed to alter the levels of cyclic AMP or tyrosine hydroxylase activity. This suggests that uptake was the primary inactivating mechanism of adenosine action in these cells. We conclude that both cell types generated adenine nucleotides which activate the adenosine receptor in an autocrine or paracrine fashion. We found that PC12 cells released ATP in a calcium‐dependent process in response to activation of the nicotinic receptor. We also measured the rates of degradation of exogenous ATP, ADP, and AMP by PC12 cells. We found that the rates of metabolism of the former two were at least an order of magnitude greater than that of AMP. Any released ATP would be rapidly metabolized to AMP and then more slowly degraded to adenosine. That this situation reflects metabolism in vivo in the PC12 cells is suggested by the finding that AMP deaminase was more effective than adenosine deaminase in decreasing basal cyclic AMP and tyrosine hydroxylase activity.
Accumulation of Arachidonic Acid Cyclo‐ and Lipoxygenase Products in Rat Brain During Ischemia and Reperfusion: Effects of Treatment with GM1‐Lactone
Authors: Petroni A. , Bertazzo A. , Sarti S. , Galli C.
Published: October 2006

The aim of our study was to investigate the changes of various biochemical parameters (concentrations of lactate, free arachidonate, cyclo‐ and lipoxygenase products) in rat brain after ischemia and reperfusion and the effects of pre‐treatment with the ganglioside derivative GM1‐lactone on the same parameters. Ischemia was induced by reversible occlusion of common carotid arteries for 20 min, which in‐cluded a final 5 min of respiration of 5% oxygen in nitrogen. Reperfusion was obtained by removing the occlusion. Pre‐ischemic conditions were obtained on sham‐operated animals. Animals were killed by microwave irradiation of their heads. Brain levels of lactate and of free arachidonate were markedly increased after ischemia and returned to normal values at 5 min of reperfusion. Levels of the cyclooxygenase metabolites prostaglandin F2α, 6‐keto‐prostaglandin F1α, and thromboxane B2 were increased after ischemia, whereas levels of the lipoxygenase metabolite leukotriene C, (LTC4) did not. change. After reperfusion, a very' marked increase of the cyclooxygenase products occurred but not of LTC4. Treatment with GM1‐lactone prevented the elevation of cyclo‐ and lipoxygenase metabolites especially during reperfusion, with limited effects on lactate and free arachidonate levels.
A Method for the Colorimetric Determination of Phosphorus
Authors: Sumner James B.
Published: October 2006

A method is described for the colorimetric determination of phosphorus, using ferrous sulfate as a reducing agent.

I wish to express my gratitude to the Rockefeller Foundation for financial assistance.
Species-Specific Perceptual Processing of Vocal Sounds by Monkeys
Authors: Zoloth Stephen R. , Petersen Michael R. , Beecher Michael D. , Green Steven , Marler Peter , Moody David B. , Stebbins William
Published: October 2006

Monkeys of four species were trained to discriminate between sets of natural tonal calls of Japanese macaques (
Macaca fuscata
) by the position of a frequency-inflection peak or by initial pitch. The Japanese macaques consistently performed best on peak position and the other species on pitch. The results imply special strategies for perceptual processing of vocal sounds and suggest parallels with human speech perception.
Genetic Regulation: The Lac Control Region
Authors: Dickson Robert C. , Abelson John , Barnes Wayne M. , Reznikoff William S.
Published: October 2006

The nucleotide sequence of the lac promoter-operator region has been determined. The 122 base pairs comprising this region include the recognition sites for RNA polymerase, the positive regulatory protein, CAP, and the negative regulatory protein, the repressor. Identification of mutant variants of the sequence combined with the in vitro biochemical studies of others has allowed us to tentatively identify the recognition site for each of these proteins, and to suggest how CAP might act at a distance to affect the interaction of RNA polymerase with the promoter.
Induction by Soluble Factors of Organized Axial Structures in Chick Epiblasts
Authors: Mitrani Eduardo , Shimoni Yael
Published: October 2006

Inductive action of soluble factors was tested on isolated chick epiblasts. An assay was developed wherein conditioned medium derived from the
Xenopus
XTC cell line induced the formation of a full-length notochord and rows of bilaterally symmetric somites. Basic fibroblast growth factor, epidermal growth factor, retinoic acid, and transforming growth factor type β1 and β2 were not capable of inducing axial structures. Thus, soluble factors can elicit the development of polarity stored in the epiblast and behave as true morphogens since they can induce the formation of the organized complex structures that constitute the embryonic axis.
5-Methyltetrahydrofolic Acid Is Not a Methyl Donor for Biogenic Amines: Enzymatic Formation of Formaldehyde
Authors: Meller Emanuel , Rosengarten Helen , Friedhoff Arnold J. , Stebbins Robert D. , Silber Robert
Published: October 2006

Contrary to previous reports, 5-methyltetrahydrofolic acid does not mediate the methylation of dopamine to epinine. Instead, this methyl donor is degraded enzymatically to formaldehyde, which condenses with dopamine to form a tetrahydoisoquinoline derivative. The latter has chromatographic characteristics very similar to those of epinine, which likely accounts for the original misidentification of the product.
Ciliary Membrane Alterations Occurring in Experimental
Mycoplasma pneumoniae
Infection
Authors: Carson Johnny L. , Collier Albert M. , Clyde Wallace A.
Published: October 2006

Experimental infection of hamster ciliated tracheal epithelium in organ culture with virulent
Mycoplasma pneumoniae
resulted in the deterioration of ciliary necklaces and an altered distribution of membrane-associated particles on the shafts of the affected cilia. To our knowledge this is the first report of an altered disposition of ciliary membrane-associated particles in response to a specific infectious agent.
Seasonal Variations in the Stable Carbon Isotopic Signature of Biogenic Methane in a Coastal Sediment
Authors: Martens Christopher S. , Blair Neal E. , Green Carol D. , Des Marais David J.
Published: October 2006

Systematic seasonal variations in the stable carbon isotopic signature of methane gas occur in the anoxic sediments of Cape Lookout Bight, a lagoonal basin on North Carolina's Outer Banks. Values for the carbon isotope ratio (δ
13
C) of methane range from -57.3 per mil during summer to -68.5 per mil during winter in gas bubbles with an average methane content of 95%. The variations are hypothesized to result from changes in the pathways of microbial methane production and cycling of key substrates including acetate and hydrogen. The use of stable isotopic signatures to investigate the global methane cycle through mass balance calculations, involving various sediment and soil biogenic sources, appears to require seasonally averaged data from individual sites.
Color Vision and Brightness Discrimination in Two-Month-Old Human Infants
Authors: Peeles David R. , Teller Davida Y.
Published: October 2006

A red or white bar, embedded in a white screen, was systematically varied in intensity. Infants consistently located and stared at the white bar unless it closely matched the screen in intensity. They also stared at all intensities of the red bar, presumptively including the red-white brightness match, and hence must have some form of color vision.
Delivery of a Quaternary Pyridinium Salt Across the Blood-Brain Barrier by Its Dihydropyridine Derivative
Authors: Bodor N. , Shek E. , Higuchi T.
Published: October 2006

A dihydropyridine-pyridine type redox system was successfully applied for delivering a quaternary pyridinium salt,
N
-methylpyridinium-2-aldoxime chloride (2-PAM), through the blood-brain barrier. The dihydropyridine derivative of 2-PAM was quickly oxidized to 2-PAM after crossing the blood-brain barrier. As a result of this approach, the brain cholinesterase blocked by organophosphates could be reactivated. The new method should be useful in delivering numerous drugs which are otherwise inaccessible to the brain because of their polar ionic character.
Origin of Life: Clues from Relations Between Chemical Compositions of Living Organisms and Natural Environments
Authors: Banin Amos , Navrot Jerzy
Published: October 2006

When elemental enrichment factors in living organisms are plotted against the ionic potential of the elements, a strikingly similar pattern is found for different groups of organisms; the pattern is also similar, in its general features, to that found in seawater. These relationships support the idea that life began in a water-rich environment interfacing with the primitive atmosphere of the earth.
Direct Observation of Domains in Wet Lipid Bilayers
Authors: Hui S. W. , Parsons D. F.
Published: October 2006

Domain structure and phase separation in hydrated lipid bilayers have been imaged directly by selected reflection dark-field electron microscopy. Domains in multicomponent bilayers are much smaller than those in single component bilayers, in agreement with results obtained by selected area electron diffraction.
Deficits in Binocular Depth Perception in Cats After Alternating Monocular Deprivation
Authors: Blake Randolph , Hirsch Helmut V. B.
Published: October 2006

Allowing very young kittens to see with only one eye at a time greatly reduces the proportion of binocular cortical cells. Compared to normal cats these specially reared animals suffer deficits in binocular depth perception while retaining normal acuity in the two eyes. Evidently, binocular cells play a crucial role in stereopsis.
Canadian Men of Science
Authors: Noble William J. , Haley K. D. C.
Published: October 2006

Even by American standards, the far western universities of British Columbia and Saskatchewan have been outstanding producers of scientists. Next have been the small Maritime Province universities of Acadia and Mount Allison. The larger universities in Ontario and Quebec were much lower in scientific productivity, and the Roman Catholic school slowest of all. Nearly half of the Canadian scientists have migrated to the United States, and, of those remaining in Canada, nearly half went to Ontario. Of the mathematicians, physicists, and psychologists, considerably more than half emigrated to the United States, whereas of the biologists, geologists, and chemists, considerably more than half remained in Canada. Two-thirds of Canada's future scientists go abroad for graduate training. Teaching remains the dominant profession for the top scientists, with some trend in evidence toward government and industry.
Instrumentation for Bioengineering
Authors: Frank Wallace E.
Published: October 2006

A tremendous range of physical science problems and techniques, from all branches of engineering, are involved in bioengineering instrumentation. The examples I have cited typify the problems that arise, but the techniques we have used represent only an infinitesimal fraction of the resources that we must exploit. The main challenge to the bioengineer is that of defining the problem in terms of what is useful and economically justified. One must understand the possibilities of engineering development and the probability that an effort will reach any assignable goal within a given time. Only then is it possible to work out a practical solution to the instrumentation problem. It is very easy to become so absorbed in the engineering development that we lose sight of the final goal and the purpose of the development. It is also easy, in working out an experiment, to become obsessed with the need for a particular bit of data, or of too great a degree of precision, without considering that the cost of obtaining these data might not be justified by their value to the full development. Thus, the only principles that can be generally applied to a bioengineering problem are those which would apply to making any decision that leans heavily on judgment.
Incentive Contrast in Honey Bees
Authors: Bitterman M. E.
Published: October 2006

Bees trained to come to the laboratory for a 20 percent sucrose solution accept it readily, but bees trained with a 40 percent sucrose solution and tested with the 20 percent solution show a pattern of interrupted feeding that may last for several minutes. Bees trained with 20 percent and tested with 40 percent sucrose are undisturbed. When the animals are offered two samples of the 20 percent solution simultaneously, they drink to repletion from whichever they first taste on each visit, but if both a 20 percent and a 40 percent drop are offered the 20 percent solution is rejected after a single experience of the 40 percent solution. Although these results are analogous in many respects to incentive contrast effects found in mammals, they can be understood in sensory terms and do not require the assumption of learning about reward.
Taste Thresholds for Phenylthiourea among Ashkenazic Jews
Authors: Saldanha P. H. , Beçak W.
Published: October 2006

Taste thresholds for phenylthiourea were measured for 244 Ashkenazic Jews. The frequency of nontasters was 27.86 percent. In the sample, 102 individuals were of pure Polish ancestry, and the frequency of nontasters among these was significantly different from the frequencies of nontasters among Europeans and Mongoloids.
Use of an Organic Carbon Dioxide Buffer in vivo
Authors: Nahas Gabriel G.
Published: October 2006

The compound 2-amino-2(hydroxymethyl)1,3-propane diol was administered intravenously to apneically oxygenated dogs over a 1-hour period. Arterial blood
p
H remained normal, and an estimated 18 to 28 percent of the CO
2
produced during apnea was recovered in the urine.
Interaction of Curare and Related Substances with Acetylcholine Receptor-Like Protein
Authors: Ehrenpreis Seymour
Published: October 2006

Existence of a receptor protein for acetylcholine has been postulated, and the hypothesis has been supported by experiments in intact cells. A protein from electric tissue has now been obtained in solution; there is striking parallelism between the ability of this protein to bind acetylcholine analogs and the effects of such analogs on electrical manifestations of intact electroplax.
Etiology of Keratogenic Metaplasia in the Chorioallantoic Membrane
Authors: Moscona A. , Carneckas Z. I.
Published: October 2006

The effects of elevated O
2
and CO
2
concentrations on the occurrence of experimental keratogenic metaplasia in the chorion of the chick embryo were examined. Exposure to oxygen resulted in advanced keratinization of the chorion; carbon dioxide at elevated concentrations, in mixtures with air or oxygen, repressed the appearance of metaplastic changes, and the chorion retained its respiratory characteristics. The evidence reported here suggests that reduction of the CO
2
content in the gaseous environment of the chorion is causally contributory to the onset of the metaplastic events.
Maximal Photosynthetic Rates in Nature
Authors: Verduin Jacob , Whitwer E. Eloise , Cowell Bruce C.
Published: October 2006

It seems likely that turbulence under natural conditions, both aquatic and terrestrial, is higher than it is in the bottles or leaf chambers used when photosynthesis is measured experimentally. Most of the maximal photosynthetic rates reported in the literature are probably lower than those which occur in nature.
Fat and Growth during Childhood
Authors: Garn Stanley M. , Haskell Joan A.
Published: October 2006

Fat thickness, size, and maturity status are significantly correlated from 1.5 through 11.5 years in both sexes. Children who are fatter than their contemporaries at 8.5 to 9.5 years reach menarche earlier and complete epiphysial union sooner.
In vitro Culture of Ehrlich Ascites Tumor Cells
Authors: Deschner Eleanor E. , Allen Bruce R.
Published: October 2006

The successful culturing and subculturing of ascites tumor cells for 80 odd days are described, as well as the growth pattern of these cells during this period. The cytological appearance of cells after 3 weeks in tissue culture and reinoculation into mice is also presented.
Suppression of Radiation-Induced Tumorization in Fern Prothalli
Authors: Partanen Carl R.
Published: October 2006

By quantitative techniques it has been shown that the expected tumor frequency after x-irradiation of spores of the fern
Pteridium aquilinum
can be reduced by the addition of casein hydrolyzate or amino acids to the medium upon which the spores are germinated and grown into either prothalli or tumors.
Species Differentiation of Insects by Hemolymph Electrophoresis
Authors: van Sande Marc , Karcher Denise
Published: October 2006

By means of microelectrophoresis in agar gel, we studied the hemolymph proteins of different species of the family Triatomidae (class Insecta) and different species of the families Ixodidae and Argasidae (class Arachnoidea). The results show a specific electrophoretic pattern for each species. Insects infected with pathogenic organisms have the same pattern as normal insects.
Connection between
Archaeopteris
and
Callixylon
Authors: Beck Charles B.
Published: October 2006

Characters of two Upper Devonian genera,
Archaeopteris
, often considered to be a fern, and
Callixylon
, classified with the gymnosperms, have been recognized in a single specimen.
Electrographic Evidence of Impaired Brain Function in Chronically Anxious Patients
Authors: Wells Charles E. , Wolff Harold G.
Published: October 2006

In a study of cerebral function by electroencephalographic techniques the following observations have been made. (i) In intact subjects, repeated stimulation with bright light causes a predictable change (alpha blocking) in the electroencephalogram, whereas repeated auditory stimulation does not. (ii) If, however, an auditory stimulus is presented repeatedly just before the visual stimulus, the sound temporarily but predictably acquires the property of the light to suppress the alpha activity. (iii) This linkage between sound and light occurs much less frequently in human subjects with known amounts of structural brain damage. (iv) A similar electrophysiological defect, implying impairment of brain function, occurs in patients showing severe anxiety during prolonged periods of difficulty in over-all adaptation.
Serial Lactic Dehydrogenase Activity in Plasma of Mice with Growing or Regressing Tumors
Authors: Riley Vernon , Wroblewski Felix
Published: October 2006

Close correlation has been observed between the serially tested plasma level of a glycolytic enzyme, lactic dehydrogenase, and the growth of several transplanted mouse tumors. The character of the lactic dehydrogenase curve determined by serial blood sampling of the animals during the development of such tumors is found to consist of five separate phases. The first three appear before any visible evidence of tumor growth. Inhibition or regression of tested tumors, induced by therapeutic compounds, was accurately reflected in a corresponding reduction of lactic dehydrogenase activity in the peripheral plasma of the host.
Immunological Technique for Protein Isolation
Authors: Sutherland G. Bonar
Published: October 2006

Carefully coagulated antibody or antigen-antibody complexes may be used as specific adsorbents for antigen, and the antigen may be released subsequently by increasing the acidity. No cross adsorption appears to take place. The procedure may prove useful for the isolation of tissue-specific proteins (including those in disease states), toxins, or viruses.
Color Phenomena
Authors: Pastore Nicholas
Published: October 2006

A procedure is described which leads to reports of hues for two black figures, one of which is shadowed. Typically, the shadowed figure is seen as blue, the other as black.
Long-Term Survival of Xenogeneic Pancreatic Islet Grafts Induced by CTLA4lg
Authors: Lenschow Deborah J. , Zeng Yijun , Thistlethwaite J. Richard , Montag Anthony , Brady William , Gibson Marylou G. , Linsley Peter S. , Bluestone Jeffrey A.
Published: October 2006

Antigen-specific T cell activation depends on T cell receptor-ligand interaction and costimulatory signals generated when accessory molecules bind to their ligands, such as CD28 to the B7 (also called BB1) molecule. A soluble fusion protein of human CTLA-4 (a protein homologous to CD28) and the immunoglobulin (Ig) G1 Fc region (CTLA4Ig) binds to human and murine B7 with high avidity and blocks T cell activation in vitro. CTLA4Ig therapy blocked human pancreatic islet rejection in mice by directly affecting T cell recognition of B7
+
antigen-presenting cells. In addition, CTLA4Ig induced long-term, donor-specific tolerance, which may have applications to human organ transplantation.
Biphasic Action of Reserpine and Isocarboxazid on Behavior and Serotonin Metabolism
Authors: Brune Guenter G. , Himwich Harold E.
Published: October 2006

In longitudal studies on psychiatric patients receiving therapeutic doses of reserpine and isocarboxazid, singly or in combination, we observed that the aggravation of psychotic symptoms sometimes occurring during treatment with reserpine was associated with a marked rise in urinary 5-hydroxyindoleacetic acid. Tranquilization was accompanied by a more moderate increase under the influence of reserpine, or by a reduction of 5-hydroxyindoleacetic acid excretion while on monoamineoxidase inhibitor medication. It is concluded that a moderate rise of free serotonin in the brain is associated with tranquilization, while a greater increase is accompanied by excitation.
Shear Rate Dependence of the Viscosity of Whole Blood and Plasma
Authors: Wells Roe E. , Merrill Edward W.
Published: October 2006

The analysis of the shear stress/shear rate relationship, and thus the viscosity/shear rate relation, of blood and plasma shows that (i) freshly drawn whole blood has a large shear rate dependence on viscosity (viscosity falls as shear rate increases), and (ii) the shear rate dependence of viscosity of whole blood, or plasma, that has not been treated to prevent clotting is substantially greater than that of whole blood or plasma treated with anticoagulants. The influence of this phenomenon upon the fluid mechanics of the microcirculation is commented upon.
Active Transport of Calcium by Rat Duodenum in vivo
Authors: Wasserman R. H. , Kallfelz F. A. , Comar C. L.
Published: October 2006

In studies of the living rat, it was observed that ionic calcium is transferred against a concentration gradient and an electropotential gradient by the duodenal membrane; this would constitute evidence for the active transport of calcium in intestinal absorption and corroborates earlier observations made in vitro. The significance of this process in regard to total calcium absorption is unknown at present.
Transfėr of Allergic Encephalomyelitis by Lymph Node Cells in Inbred Guinea Pigs
Authors: Stone Sanford H.
Published: October 2006

Severe or lethal allergic encephalomyelitis was transferred between histocompatible guinea pigs by lymphoid cells capable of persistence in a viable state in the recipient. For optimum induction of passive disease, cells must be transferred before the day on which the disease becomes manifest in the donor.
Formation of the Periostracum in
Mercenaria mercenaria
Authors: Hillman Robert E.
Published: October 2006

A series of histochemical tests performed on the mantle of the northern quahog
Mercenaria mercenaria
L. suggest that the epithelium of the inner surface of the first fold and the underlying secretory cells function together in the formation of the periostracum in this mollusk. The secretory cells supply a phenolic substrate which, when oxidized, provides quinones capable of tanning the periostracum.
Culture and Cognition
Authors: Wallace Anthony F. C.
Published: October 2006

Anthropologists are turning their attention to the cognitive structures which are basic to customary behavior in society. In general, these studies work to expose the abstract calculus underlying the specific content of behavior by the use of a symbolic notation and the application of available logical-mathematical models as hypotheses. Particular attention has been paid to the semantic analysis of folk taxonomies, such as kinship terminologies, but formal analysis of other aspects of culture, such as values, the program of behavior released in particular situations, and folk science, is also a promising area of work. The principles of the metacalculi to which the diverse cognitive structures of individuals sum in stable social systems are, then, to be regarded as principles of sociocultural organization itself.
Iodine-125 as a Protein Label in Immunology
Authors: Fitch Frank W. , Winebright James , Harper Paul V.
Published: October 2006

Iodine-125 has the relatively long half-life of 60 days, and emits 27.3- to 35.5-kev photon radiation, permitting counting in an ordinary well crystal scintillation counter with 30 to 40 percent efficiency. The emission of low-energy electrons having the same general energy range as tritium beta radiation electrons allows high-resolution autoradiography. These properties, together with the other advantages of radioactive iodine, make this nuclide a particularly satisfactory label for immunologically active proteins.
"Productivity" of Undergraduate Institutions
Authors: Astin Alexander W.
Published: October 2006

A new method for evaluating the "Ph.D. productivity" of undergraduate institutions was applied to a sample of 265 institutions. It was found that a college's actual Ph.D. output can be predicted relatively accurately from an "expected" output based on the sex, major fields, and intelligence level of its students. Public institutions were found to be significantly overproductive, and eastern men's colleges and universities were found to be significantly underproductive. Previous findings indicating that the faculty had a causative effect on productivity were not confirmed. These results suggest that Ph.D. productivity may not be a sensitive measure of the effectiveness of undergraduate institutions.
Mechanism of Transduction by Retroviruses
Authors: Swain Amanda , Coffin John M.
Published: October 2006

Retroviruses can capture cellular sequences and express them as oncogenes. Capture has been proposed to be a consequence of the inefficiency of polyadenylation of the viral genome that allows the packaging of cellular sequences flanking the integrated provirus in virions; after transfer into virions, these sequences could be incorporated into the viral genome by illegitimate recombination during reverse transcription. As a test for this hypothesis, a tissue culture system was developed that mimics the transduction process and allows the analysis and quantitation of capture events in a single step. In this model, transduction of sequences adjacent to a provirus depends on the formation of readthrough transcripts and their transmission in virions and leads to various recombinant structures whose formation is independent of sequence similarity at the crossover site. Thus, all events in the transduction process can be attributed to the action of reverse transcriptase on readthrough transcripts without involving deletions of cellular DNA.
Context Dependence of Hydrogen Bond Free Energy Revealed by Substitutions in an RNA Hairpin
Authors: SantaLucia John , Kierzek Ryszard , Turner Douglas H.
Published: October 2006

Prediction and modeling of RNA structure requires knowledge of the free energy contributions of various interactions. Many unusual hydrogen bonds were recently proposed in the structure of a
GCAA
hairpin determined from nuclear magnetic resonance. The contributions of these hydrogen bonds to the folding stability of the hairpin formed by rGGC
GCAA
GCC have now been investigated through the use of functional group substitutions. These and previous results suggest a strong context dependence for the free energy of hydrogen bond formation. The results also suggest that the phylogenetic preference for GNRA (where N = A, C, G, or U and R = A or G) tetraloops may have a functional rather than thermodynamic basis.