bluuebunny/crossref_metadata_2025 huggingface dataset:
Tachykinin Receptors of the NK1 Type (Substance P) Coupled Positively to Phospholipase C on Cortical Astrocytes from the Newborn Mouse in Primary Culture
Authors: Torrens Y. , De Montety M. C. Daguet , El Etr M. , Beaujouan J. C. , Glowinski J.
Published: October 2006

Abstract: Specific 125I‐Bolton‐Hunter substance P (125I‐BHSP) binding sites are present on intact cortical astrocytes of the newborn mouse in primary culture. Therefore, these cells were used to ascertain the existence of functional substance P (SP) receptors coupled positively to phospholipase C. SP stimulated phosphoinositide breakdown with an EC50 value (4.5 × 10−10M) similar to its IC50 value (3.8 × 10−10M) for inhibiting 125I‐BHSP binding. The maximal response (to 10−6M SP for 60 min) obtained was ∼500% of control values. The rank order of potency of tachykinins was SP > neurokinin (NK) A > NKB. Long SP C‐terminal fragments were more potent than shorter ones in stimulating the accumulation of 3H‐inositol phosphates. SP free acid and SP N‐terminal fragments were without effect. [L‐Pro9]SP and SP methyl ester, two selective agonists of NK1 receptors, were almost as potent as SP. An excellent correlation was found when the abilities of tachykinins and their analogs for stimulating phosphoinositide breakdown and for inhibiting 125I‐BHSP binding were compared. Finally, when used at a concentration of 3 × 10−6M, spantide ([D‐Arg1, D‐Trp7,9, Leu11]SP), an SP antagonist, competitively reduced the stimulatory effect of SP on accumulation of 3H‐inositol phosphates. These results demonstrate the presence of functional SP receptors (NK1) on cortical astrocytes from the newborn mouse in primary culture.
Low‐Density Lipoprotein Receptor on Endothelium of Brain Capillaries
Authors: Méresse Stéphane , Delbart Christiane , Fruchart Jean‐Charles , Cecchelli Roméo
Published: October 2006

Abstract: The presence of lipoproteins, apolipoproteins, and their receptors in the brain could provide a system for cholesterol homeostasis, as they do in other tissues. This study was undertaken to determine whether plasma low‐density lipoprotein, the major carrier of cholesterol, is involved in the delivery of lipids through the blood‐brain barrier. 125I‐Labeled low‐density lipoprotein bound to a specific receptor on the endothelium of brain capillaries when it was injected immediately postmortem into bovine brain circulation. In contrast, no specific binding of 125I‐low density lipoprotein was found when the incubations were performed with isolated capillaries. Incubations of endothelial or basement membranes of brain capillaries with 125I‐low density lipoprotein demonstrated a high‐affinity association of low‐density lipoprotein with the membranes of bovine cerebral endothelial cells. The specificity of the low‐density lipoprotein binding was determined in several ways using a dot blot assay. This receptor shows the same characteristics as the low‐density lipoprotein receptor on human fibroblasts. The molecular weight of the bovine brain capillary low‐density lipoprotein receptor (132,000) was determined by ligand blotting. These results demonstrated the occurrence of a low‐density lipoprotein receptor on the endothelial cells of brain capillaries.
Relationship Between Plasma and Cerebrospinal Fluid Norepinephrine and Dopamine Metabolites in a Nonhuman Primate
Authors: Greene Karl A. , Faull Kym F.
Published: October 2006

Abstract: Major and minor pathways of metabolism in the mammalian CNS result in the formation of 3‐methoxy‐4‐hydroxyphenylethylene glycol (MHPG) and normetane‐phrine (NMN) from norepinephrine (NE), and homovanillic acid (HVA) and 3‐methoxytyramine (3‐MT) from dopamine (DA), respectively. The correlational relationships between HVA and 3‐MT and between MHPG and NMN in primate CSF and plasma have not been described. These relationships may help to elucidate the usefulness of CSF and plasma metabolites as indices of CNS NE and DA activity. In addition, because NMN is unlikely to cross the blood‐brain barrier, CSF NMN concentrations would not be confounded by contributions from plasma, which is a major issue with CSF MHPG. We have obtained repeated samples of plasma and CSF from drug‐naive male squirrel monkeys and have measured the concentrations of MHPG, HVA, NMN, and 3‐MT to define their correlational relationships. For the NE me‐tabolites, significant correlations were obtained for CSF MHPG and NMN (r = 0.806, p < 0.001), plasma MHPG and CSF NMN (r= 0.753, p < 0.001), and plasma and CSF MHPG (r= 0.776, p< 0.001). These results suggest that CSF and plasma MHPG and CSF NMN may reflect gross changes in whole brain steady‐state noradrenergic metabolism. Only a single significant relationship was demonstrated for the DA metabolites, with CSF 3‐MT correlating with plasma HVA (r= 0.301, p < 0.025). The results for the DA metabolites probably reflect regional differences in steady‐state brain dopaminergic metabolism.
Inhibition of Amino Acid Transport and Protein Synthesis by HgCl2 and Methylmercury in Astrocytes: Selectivity and Reversibility
Authors: Brookes N. , Kristt D. A.
Published: October 2006

Abstract: The previously reported observation that submi‐cromolar concentrations of HgCl2 inhibit glutamate uptake reversibly in astrocytes, without effect on 2‐deoxyglucose uptake, suggested that elemental mercury vapor, which is oxidized to mercuric mercury in the brain, might cause neurodegenerative change through the mediation of glutamate excitotoxicity. Here, selectivity is explored further by measuring the inhibition of other amino acid transporters and protein synthesis as a function of HgCl2 concentration. The properties of MeHgCl were compared under identical conditions, and some morphological correlates of function were examined. Inhibition of amino acid transport by HgCl2 was selective, whereas MeHgCl was nonselective. The 50% inhibitory concentrations of HgCl2 for uptake of α‐aminoiso‐butyric acid by system A, uptake of α‐aminoisobutyric acid or kynurenine by a system L variant, and uptake of γ‐ami‐nobutyric acid were all two‐ to fourfold greater than that for uptake of glutamate. The submicromolar concentrations of HgCl2 that inhibited glutamate transport also inhibited protein synthesis, but in a rapidly reversible fashion, and elicited only discrete ultrastructural changes (heterochromatin. increased numbers of lysosomal bodies, and increased complexity of cell surface). In contrast, inhibition of protein synthesis by MeHgCl was acutely (1‐h) irreversible and became marked only at concentrations higher than those that elicited gross morphologic change in the form of “bleb”‐like swellings. The results lend support to the proposed excitotoxic mediation of mercury vapor neurotoxicity and reveal a sharp contrast between the effects of HgCl2 and MeHgCl on astrocytes.
Creatine Transport in Cultured Cells of Rat and Mouse Brain
Authors: Möller Andreas , Hamprecht Bernd
Published: October 2006

Abstract: Astroglia‐rich cultures derived from brains of newborn rats or mice use a transport system for the uptake of creatine. The uptake system is saturable, Na+‐dependent, and highly specific for creatine and Na+. Kinetic studies on rat cells revealed a Km value for creatine of 45 μM, a Vmax of 17 nmol X h−1 X (mg of protein)−1, and a Km value of 55 mM for Na+. The carrier is competitively inhibited by guanidinopropionate (Ki= 15 μM). No such transport system was found in neuron‐rich primary cultures from embryonic rat brain. It is hypothesized that creatine transport is an astroglial rather than a neuronal function.
Effect of 6‐Phosphogluconate on Phosphoglucose Isomerase in Rat Brain In Vitro and In Vivo
Authors: Gaitonde M. K. , Murray Elizabeth , Cunningham Vincent J.
Published: October 2006

Abstract: The activity of phosphoglucose isomerase, its kinetic properties, and the effect of 6‐phosphogluconate on its activity in the forward (glucose 6‐phosphate ± fructose 6‐phosphate) and the reverse (fructose 6‐phosphate ± glucose 6‐phosphate) reactions were determined in adult rat brain in vitro. The activity of phosphoglucose isomerase (in nmol/min/mg of whole brain protein) was 1,865 ± 20 in the forward reaction and 1,756 ± 32 in the reverse reaction at pH 7.5. It was 1,992 ± 28 and 2,620 ± 46, respectively, at pH 8.5. The apparent Km and Vmax of phosphoglucose isomerase were 0.593 ± 0.031 mM and 2,291 ± 61 nmol/min/mg of protein, respectively, for glucose 6‐phosphate and 0.095 ± 0.013 mM and 2,035 ± 98 nmol/min/mg of protein, respectively, for fructose 6‐phosphate. The activity of phosphoglucose isomerase was inhibited intensely and competitively by 6‐phosphogluconate, with an apparent Ki of 0.048 ± 0.005 mM for glucose 6‐phosphate and 0.042 ± 0.004 mM for fructose 6‐phosphate as the substrate. With glucose 6‐phosphate as the substrate, at concentrations from 0.05 to 0.5 mM, the activity of the enzyme was inhibited completely in the presence of 0.5–2.0 nM 6‐phosphogluconate. With 0.05–0.2 nM fructose 6‐phosphate as the substrate, it was inhibited ∼85% at the same concentrations of the inhibitor. No significant changes were observed in the values of Km, Vmax, and Ki; for phosphoglucose isomerase in the brain of 6‐aminonicotinamide‐treated rats. These findings in vitro and the results of previous experiments, showing an increase from negligible levels to 1.5 mM 6‐phosphogluconate in the brain after administration of 6‐aminonicotinamide to rats, were discussed in support of the view that the two pathways of glucose metabolism—the Embden‐Meyerhof pathway and the hexose monophosphate shunt—occur in distinct compartments in the brain in vivo.
Dopamine Release in Rat Striatum: Physiological Coupling to Tyrosine Supply
Authors: During Matthew J. , Acworth Ian N. , Wurtman Richard J.
Published: October 2006

Abstract: Intracerebral microdialysis was used to monitor dopamine release in rat striatal extracellular fluid following the intraperitoneal administration of dopamine's precursor amino acid, l‐tyrosine. Dopamine concentrations in dialysates increased transiently after tyrosine (50–100 mg/kg) administration. Pretreatment with haloperidol or the partial lesioning of nigrostriatal neurons enhanced the effect of tyrosine on dopamine release, and haloperidol also prolonged this effect. These data suggest that nigrostriatal dopaminergic neurons are responsive to changes in precursor availability under basal conditions, but that receptor‐mediated feedback mechanisms limit the magnitude and duration of this effect.
Phosphorylation of B‐50 (GAP43) Is Correlated with Neurotransmitter Release in Rat Hippocampal Slices
Authors: Dekker L. V. , De Graan P. N. E. , Versteeg D. H. G. , Oestreicher A. B. , Gispen W. H.
Published: October 2006

Abstract: Recent studies have demonstrated that phorbol diesters enhance the release of various neurotransmitters. It is generally accepted that activation of protein kinase C (PKC) is the mechanism by which phorbol diesters act on neurotransmitter release. The action of PKC in neurotransmitter release is very likely mediated by phosphorylation of substrate proteins localized in the presynaptic nerve terminal. An important presynaptic substrate of PKC is B‐50. To investigate whether B‐50 mediates the actions of PKC in neurotransmitter release, we have studied B‐50 phosphorylation in intact rat hippocampal slices under conditions that stimulate or inhibit PKC and neurotransmitter release. The slices were labelled with [32P]orthophosphate. After treatment, the slices were homogenized, B‐50 was immunoprecipitated from the slice homogenate, and the incorporation of 32P into B‐50 was determined. Chemical depolarization (30 μM K+) and the presence of phorbol diesters, conditions that stimulate neurotransmitter release, separately and in combination, also enhance B‐50 phosphorylation. Polymyxin B, an inhibitor of PKC and neurotransmitter release, decreases concentration dependently the depolarization‐induced stimulation of B‐50 phosphorylation. The effects of depolarization are not detectable at low extracellular Ca2+ concentrations. It is concluded that in rat hippocampal slices B‐50 may mediate the action of PKC in neurotransmitter release.
Blood–Brain Barrier Breakdown in Cold‐Injured Brain Is Linked to a Biphasic Stimulation of Ornithine Decarboxylase Activity and Polyamine Synthesis: Both Are Coordinately Inhibited by Verapamil, Dexamethasone, and Aspirin
Authors: Koenig Harold , Goldstone Alfred D. , Lu Chung Y.
Published: October 2006

Abstract: An early increase in ornithine decarboxylase (ODC) activity and polyamine levels in rat cerebral capillaries was previously implicated in the mediation of blood–brain barrier (BBB) breakdown in cold‐injured brain. A time course study in rat cerebrum indicated that cold injury evokes a biphasic increase in ODC activity and polyamine levels in perilesional cortex. ODC activity rose sharply (fourfold) within 1 min, remained elevated for 5 min, and then returned to the basal level by 10 min. A transient rise in polyamine concentration followed in the rank order of putrescine > spermidine > spermine. A secondary rise in ODC activity commenced in perilesional tissue at 2–6 h and peaked (8.8‐fold) at 48 h. Major increases in the content of putrescine (330%), spermidine (103%), and spermine (50%) developed at 48–72 h. α‐Difluoromethylornithine (DFMO), a specific irreversible inhibitor of ODC, suppressed the evoked increase in ODC activity and abolished the associated increase in content of polyamines, findings indicating that the accumulation of polyamines in cryoinjured brain reflects enhanced synthesis resulting from an ODC‐mediated increase in putrescine content. Cycloheximide and actinomycin D were without effect on the early increase in ODC activity but inhibited the delayed increase in ODC activity, an observation suggesting that the initial increase in activity reflects an activation of a cryptic ODC via a posttranslational process, whereas the delayed increase in activity results from ODC synthesis mainly under transcriptional control. Because membrane phospholipid degradation, release of diacylglycerol and free arachidonic acid, and prostaglandin formation are early events in cold‐injured brain, we assessed the effects of verapamil (a calcium channel blocker), dexamethasone (which inhibits arachidonic acid release), and aspirin (a cyclooxygenase inhibitor). These agents resembled DFMO in that they inhibited the early (2‐min) and delayed (24‐h) increase in ODC activity and polyamine concentrations and concurrently attenuated BBB breakdown in the perilesional cortex, as monitored by fluorescein transport. Exogenous putrescine nullified the protective effect of verapamil, dexamethasone, and aspirin on BBB breakdown following cryogenic injury. These results implicate Ca2+ influx via calcium channels, phospholipid hydrolysis, and prostaglandin synthesis in cryogenically induced stimulation of ODC activity and further strengthen the evidence linking polyamines to BBB breakdown. Changes in ODC‐regulated polyamine synthesis in brain cells may play an important role in other aspects of the pathophysiology of cerebral injury.
Light‐Induced Dopamine Release from Teleost Retinas Acts as a Light‐Adaptive Signal to the Retinal Pigment Epithelium
Authors: Dearry Allen , Burnside Beth
Published: October 2006

In the retinal pigment epithelium (RPE) of lower vertebrates, melanin pigment granules migrate in and out of the cells' long apical projections in response to changes in light condition. When the RPE is in its normal association with the retina, light onset induces pigment granules to disperse into the apical projections; dark onset induces pigment granules to aggregate into the cell bodies. However, when the RPE is separated from the retina, pigment granule movement in the isolated RPE is insensitive to light onset. It thus seems likely that a signal from the retina communicates light onset to the RPE to initiate pigment dispersion. We have examined the nature of this retina‐to‐RPE signal in green sunfish, Le‐pomis cyanellus. In isolated retinas with adherent RPE, light‐induced pigment dispersion in the RPE is blocked by treatments known to block Ca2+‐dependent transmitter release in the retina. In addition, the medium obtained from incubating previously dark‐adapted retinas in the light induces light‐adaptive pigment dispersion when added to isolated RPE. In contrast, the medium obtained from incubating dark‐adapted retinas in constant darkness does not affect pigment distribution when added to isolated RPE. These results are consistent with the idea that RPE pigment dispersion is triggered by a substance that diffuses from the retina at light onset. The capacity of the conditioned medium from light‐incubated retinas to induce pigment dispersion in isolated RPE is in hibited by a D2 dopamine antagonist, but not by D! or α‐adrenergic antagonists. Light‐induced pigment dispersion in whole RPE‐retinas is also blocked by a D2 dopamine antagonist. These results suggest that the diffusible substance is dopamine and that retinal dopamine stimulates pigment dispersion by interacting with D2 dopaminergic receptors on the RPE cell surface. Direct measurement of the endogenous catecholamine content of isolated dark‐adapted retinas and of the medium surrounding isolated retinas incubated in the dark or in the light demonstrates that dopamine is the predominant catecholamine of green sunfish retinas, and that light onset stimulates the overflow of endogenous dopamine—but not that of norepinephrine or epinephrine—from isolated retinas. These results suggest that illumination increases dopamine release in teleost retinas. Together, our findings are consistent with the idea that dopamine acts as a paracrinic messenger of light‐adaptive stimuli by diffusing from its site of release in the retina to distant nonsynaptic receptors on RPE cells.
Two Affinity States for [3H]Imipramine Binding to the Human Platelet 5‐Hydroxytryptamine Carrier: An Explanation for the Allosteric Interaction Between 5‐Hydroxytryptamine and Imipramine
Authors: O'Riordan Catherine , Phillips Orla M. , Williams D. Clive
Published: October 2006

5‐Hydroxytryptamine (5‐HT) showed a biphasic effect on the dissociation rate of [3H]imipramine from human platelet membranes: At low concentrations (EC50, ∼ 2.5 μM), 5‐HT stimulated the rate, as expected for mutually exclusive binding of 5‐HT and imipramine; at higher concentrations (EC50, ∼ 40 μM), 5‐HT reduced this stimulated rate, a result consistent with 5‐HT binding at a site that is physically distinct from both the imipramine binding site and the 5‐HT transport recognition site of the 5‐HT carrier. This modulatory effect could be mimicked by tryptamine, was saturable and independent of Na+ concentration, and could also be demonstrated for detergent‐solubilized carriers. Monophasic association kinetics for [3H]imipramine binding were found. Heat stability experiments showed biphasic thermal inactivation curves. These results are consistent with [3H]imipramine binding to two classes of binding sites at the 5‐HT carrier on human platelet membranes, with affinities three‐ to fivefold different. 5‐HT can convert the lower‐affinity state into the higher‐affinity state.
Interleukin‐1α and tumor necrosis factor‐α expression during the early phases of orthodontic tooth movement in rats
Authors: Bletsa Athanasia , Berggreen Ellen , Brudvik Pongsri
Published: October 2006

Remodelling of the periodontium after application of mechanical forces constitutes the basis of clinical orthodontics and various immunoregulatory molecules are involved in this process. The aim of this study was to investigate the expression of the cytokines interleukin‐1α (IL‐1α) and tumor necrosis factor‐α (TNF‐α) in dental tissues during the early phases of orthodontic tooth movement. Eightteen male Wistar rats were used. All maxillary right first molars were moved orthodontically, with a force of 0.5 N, for 3 h, 1 d, and 3 d. The contralateral sides served as untreated controls. Parasagittal sections of the maxillary molars and the surrounding tissues were subjected to immunohistochemical staining for IL‐1α or TNF‐α, and were evaluated with light microscopy. IL‐1α and TNF‐α were expressed in the bone and periodontal ligament (PDL) along the roots of the orthodontically moved molars and in the gingiva. Increased expression of both cytokines was observed in the aforementioned areas after 1 and 3 d of tooth movement. The pulp tissue exhibited only minor changes in cytokine expression during tooth movement. The results suggest that mechanical stress results in almost immediate inflammatory reactions in various dental tissues.
Field Focusing Nuclear Magnetic Resonance (FONAR): Visualization of a Tumor in a Live Animal
Authors: Damadian Raymond , Minkoff Lawrence , Goldsmith Michael , Stanford Michael , Koutcher Jason
Published: October 2006

A nuclear magnetic resonance (NMR) image of a tumor in a live animal is reported. The field focusing NMR method or FONAR process that now achieves the tumor outline is described.
Production of Immunity to Dengue with Virus Modified by Propagation in Mice
Authors: Sabin Albert B. , Schlesinger R. Walter
Published: October 2006

It has been demonstrated that dengue virus can be propagated by intracerebral inoculation in mice. Although initial adaptation to the mouse is a tedious and difficult process, 16 consecutive passages have been achieved already in one series and further passages are in progress. The virus propagated in mice produced dengue in human volunteers, but was not pathogenic for cotton rats, hamsters, guinea pigs or rabbits. Although it was evident that even after 2 serial passages in mice the virus produced a modified type of disease in human beings, tests with the 7th, 9th and 10th passage material indicated that the modification had become so marked that it could be used as a vaccine for the production of immunity against dengue.
Calcium Entry Leads to Inactivation of Calcium Channel in
Paramecium
Authors: Brehm Paul , Eckert Roger
Published: October 2006

Under depolarizing voltage clamp of
Paramecium
an inward calcium current developed and subsequently relaxed within 10 milliseconds. The relaxation was substantially slowed when most of the extracellular calcium was replaced by either strontium or barium. Evidence is presented that the relaxation is not accounted for by a drop in electromotive force acting on calcium, or by activation of a delayed potassium current. Relaxation of the current must, therefore, result from an inactivation of the calcium channel. This inactivation persisted after a pulse, as manifested by a reduced calcium current during subsequent depolarization. Inactivation was retarded by procedures that reduce net entry of calcium, and was independent of membrane potential. The calcium channel undergoes inactivation as a consequence of calcium entry during depolarization. In this respect, inactivation of the calcium channel departs qualitatively from the behavior described in the Hodgkin-Huxley model of the sodium channel.
Ultrasensitive Chemosensory Responses by a Protozoan to Epinephrine and Other Neurochemicals
Authors: Hauser Donald C. R. , Levandowsky M. , Glassgold Judith M.
Published: October 2006

A behavioral assay was developed based on differential tendency of a protozoan to attach to an agar gel containing the test substance. The heterotrophic marine dinoflagellate "
Crypthecodinium
(
Gyrodinium
)
cohnii
responded negatively (less tendency to attach) to epinephrine at concentrations above 5 × 10
-15
M
and to norepinephrine at concentrations above 5 × 10
-9
M
. Response to choline as choline H2 citrate, choline bitartrate, and choline chloride was negative above 10
-7
M
, but response to the choline analog carbachol was positive (greater tendency to attach) in the range 5 × 10
-6
to 5 × 10
-4
M
. Other responses to neurochemicals at comparable concentrations were: dopa, betaine, and glycine—positive; L-glutamic acid, tryptophan, putrescine, and taurine—negative. Serotonin was inert, responses to tyrosine and γ-aminobutyric acid were variable, and phenylalanine (6 × 10
-3
M
) and 5-hydroxytryptophan (5 × 10
-4
M
) were negative only at the highest concentrations tested.
Photoreceptor Shedding Is Initiated by Light in the Frog Retina
Authors: Basinger Scott , Hoffman Rosemary , Matthes Michael
Published: October 2006

Frogs maintained on a diurnal light-dark cycle (14 hours light and 10 hours darkness) shed their rod photoreceptor outer segment tips shortly after the onset of light. Shedding is synchronous and occurs in about 25 percent of the rod photoreceptors each day. Prolonged exposure to total darkness decreases the amount of shedding, after which exposure to light results in a large burst of synchronous shedding. Thus, in the frog retina, the synchronous shedding of rod outer segment tips is shown to be directly related to light stimulation.
Stimulation-produced Analgesia: Development of Tolerance and Cross-Tolerance to Morphine
Authors: Mayer David J. , Hayes Ronald L.
Published: October 2006

Analgesia resulting from focal electrical stimulation of the brain of the rat shows tolerance with repeated exposures; this tolerance dissipates after a period of nonstimulation. Addiction to morphine reduces greatly the analgesia produced by electrical stimulation of the brain, which demonstrates cross-tolerance between morphine analgesia and stimulation-produced analgesia. Recovery of the stimulation-produced analgesia is seen after discontinuing administration of morphine. These results suggest that morphine and electrical stimulation produce analgesia by common mechanisms. The fact that tolerance occurs to the analgesic effect of electrical stimulation indicates that tolerance may be an alteration of an endogenous neuronal process.
Subicular Input from Temporal Cortex in the Rhesus Monkey
Authors: Van Hoesen Gary W. , Rosene Douglas L. , Mesulam Marek-Marsel
Published: October 2006

The subicular cortices of the primate hippocampal formation form a physical and connectional link between the cortex of the temporal lobe and the hippocampus. Their direct connections with all classes of cortex in the temporal lobe except primary sensory cortex underscore the pivotal role of these areas in the potential interplay between the hippocampal formation and the association cortices.
Troponin and Parvalbumin Calcium Binding Regions Predicted in Myosin Light Chain and T4 Lysozyme
Authors: Tufty Robert M. , Kretsinger Robert H.
Published: October 2006

A computer search of available protein sequences and structures suggests that bacteriophage T4 lysozyme contains one region and that rabbit myosin light chains contain three regions similar, and supposedly homologous, to the calcium binding region of carp muscle calcium binding parvalbumin.
Symbolic Matching by Pigeons: Rate of Learning Complex Discriminations Predicted from Simple Discriminations
Authors: Carter David E. , Eckerman David A.
Published: October 2006

Pigeons had no greater difficulty learning a complex discrimination involving arbitrary interrelations among stimuli (symbolic matching) than one involving interrelations based on stimulus similarity (matching-to-sample). The relative rates of acquisition of matching and symbolic matching may be accounted for by the discriminability between sample stimuli and between comparison stimuli, with the former playing the more important role.
Neuronal excitability modulation over the sleep cycle: a structural and mathematical model
Authors: McCarley RW , Hobson JA
Published: October 2006

A model for control of the desynchronized phase of the sleep cycle postulates reciprocal interaction between cells in the pontine gigantocellular tegmental field (FTG cells) and cells in the nucleus locus coeruleus and nucleus subcoeruleus (LC cells). This physiological model leads to equations of the Lotka-Volterra type; the time course of activity predicted by the model is in good agreement with actual long-term recordings of FTG cells and single-cycle data for LC cells.
Lactosyl Ceramidosis: Normal Activity for Two Lactosyl Ceramide β-Galactosidases
Authors: Wenger David A. , Sattler Martha , Clark Cameron , Tanaka Harumi , Suzuki Kunihiko , Dawson Glyn
Published: October 2006

Lactosyl ceramide β-galactosidase activities in the fibroblasts from the previously described patient with so-called "lactosyl ceramidosis" were reexamined with the two recently developed assay methods which appear to measure two genetically distinct enzymes that can degrade this substrate. No deficiency of either of the lactosyl ceramide-cleaving enzymes was observed. In addition, sphingomyelinase activity was only one-sixth of normal, while all other enzymes examined were within the normal ranges.
Cometary Delivery of Organic Molecules to the Early Earth
Authors: Chyba Christopher F. , Thomas Paul J. , Brookshaw Leigh , Sagan Carl
Published: October 2006

It has long been speculated that Earth accreted prebiotic organic molecules important for the origins of life from impacts of carbonaceous asteroids and comets during the period of heavy bombardment 4.5 × 10
9
to 3.8 × 10
9
years ago. A comprehensive treatment of comet-asteroid interaction with the atmosphere, surface impact, and resulting organic pyrolysis demonstrates that organics will not survive impacts at velocities greater than about 10 kilometers per second and that even comets and asteroids as small as 100 meters in radius cannot be aerobraked to below this velocity in 1-bar atmospheres. However, for plausible dense (10-bar carbon dioxide) early atmospheres, we find that 4.5 × 10
9
years ago Earth was accreting intact cometary organics at a rate of at least ∼10
6
to 10
7
kilograms per year, a flux that thereafter declined with a half-life of ∼10
8
years. These results may be put in context by comparison with terrestrial oceanic and total biomasses, ∼3 × 10
12
kilograms and ∼6 × 10
14
kilograms, respectively.
Astronomical Observations with the FAUST Telescope
Authors: Bixler Jay , Bowyer Stuart , Deharveng Jean Michel , Courtès Georges , Malina Roger , Martin Chris , Lampton Michael
Published: October 2006

The far-ultraviolet space telescope (FAUST) was flown on Spacelab 1 to provide wide-field imaging in the wavelength range 1300 to 1800 angstroms. Most of the developed film showed high levels of background exposure. Frames with a lower background included exposures of the Cygnus Loop supernova remnant and an exposure in the direction of the galaxy cluster Abell 2634. Several exposures will be used in a search for hot white dwarf stars.
Sexual Cyclicity in Captive Lowland Gorillas
Authors: Nadler Ronald D.
Published: October 2006

Oppositely sexed pairs of gorillas exhibit some behavior indicative of higher cognitive functioning, such as individual partner preferences and varied copulatory positions, but also mate in a cyclic manner closely related to the degree of female genital swelling. The latter finding is contrary to predictions based on their advanced position in phylogeny.
Hyperbaric hydrogen Therapy: A Possible Treatment for Cancer
Authors: Dole Malcolm , Wilson F. Ray , Fife William P.
Published: October 2006

Hairless albino mice with squamous cell carcinoma were exposed to a mixture of 2.5 percent oxygen and 97.5 percent hydrogen at a total pressure of 8 atmospheres for periods up to 2 weeks in order to see if a free radical decay catalyzer, such as hydrogen, would cause a regression of the skin tumors. Marked regression of the tumors was found, leading to the possibility that hyperbaric hydrogen therapy might also prove to be of significance in the treatment of other types of cancer.
Genetic Control of Chloroform Toxicity in Mice
Authors: Hill Richard N. , Clemens Thomas L. , Liu Dai Kee , Vesell Elliot S. , Johnson W. Dean
Published: October 2006

Mouse strain differences suggest intermediate or multifactorial genetic control of chloroform-induced renal toxicity and death. The chloroform dose lethal to 50 percent of animals was four times higher in C57BL/6J males than in DBA/2J males. Twice as much chloroform accumulated in the kidneys of the sensitive as the resistant strain. First generation offspring were midway between parental strains for both parameters.
Morphine-Dependent Rats: Blockade of Precipitated Abstinence by Tetrahydrocannabinol
Authors: Hine B. , Friedman E. , Torrelio M. , Gershon S.
Published: October 2006

Male rats were implanted subcutaneously with a pellet containing 75 milligrams of morphine base or placebo, and naloxone hydrochloride (4 milligrams per kilogram of body weight) was administered 72 hours later. Treatment with Δ9-tetrahydrocannabinol (2, 5, or 10 milligrams per kilogram) 1 hour before naloxone administration significantly reduced the intensity of abstinence; the two higher doses blocked the appearance of wet shakes and escapes, diarrhea, and increased defecation. Δ9-Tetrahydrocannabinol did not induce abstinence itself, and prior treatment with cannabidiol was ineffective in reducing naloxoneprecipitated abstinence in animals with morphine pellets. These data suggest that Δ9-tetrahydrocannabinol may be of value in facilitating narcotic detoxification.
Polyspermy Block of
Spisula
Eggs Is Prevented by Cytochalasin B
Authors: Ziomek Carol Ann , Epel David
Published: October 2006

The eggs of the surf clam
Spisula solidissima
have a built-in mechanism that prevents polyspermy: the eggs show a 70 percent decrease in sperm receptivity 5 seconds after fertilization, and become completely resistant to sperm by 15 seconds. When the outer egg coat (vitelline layer) was removed, there was no change in fertilizability or the timing of the block to polyspermy. This suggests that the alteration occurs in or at the plasma membrane. Such changes in the egg surface were sensitive to low concentrations of cytochalasin B.
Ejaculatory Pattern in Female Rats Without Androgen Treatment
Authors: Emery Donna E. , Sachs Benjamin D.
Published: October 2006

Adult female rats receiving long-term estrogen treatment displayed the species-typical motor pattern of ejaculation during copulation. This hormone treatment produced pituitary hypertrophy and concomitant pressure damage to brain areas dorsal to the pituitary, but did not cause clitoral hypertrophy. The demonstration of the ejaculatory pattern in perinatally untreated female rats indicates that the potential for the expression of the ejaculatory or "orgasmic" pattern is not dependent on exogenous androgen at any stage of development and is more widely represented among female mammals than previously believed.
Arrhythmically Singing Crickets: Thermoperiodic Reentrainment After Bilobectomy
Authors: Rence Bradford , Loher Werner
Published: October 2006

The circadian control of the calling song of crickets is abolished by severance of the optic lobes. The arrhythmic singing activity of operated animals is unaffected by all possible light conditions, yet the singing can be reentrained by a daily temperature cycle. The characteristics of this reentrainment indicate that temperature is acting as an actual Zeitgeber. In light of these results the current hypothesis which ascribes a driving oscillator function to the optic lobes must be reevaluated.
Optical Holographic Three-Dimensional Ultrasonography
Authors: Baum Gilbert , Stroke George W.
Published: October 2006

Three-dimensional ultrasonograms prepared by superposition optical holography improves anatomical orientation and reduces the volume of data needed to study parenchymal organs such as breast, liver, kidney, spleen, and others. An optical hologram makes it possible to simultaneously view multiple planes of observations and see through and around structures without the superimposition of overlying structures. The use of pulse echo ultrasonograms results in better resolution and gray scale and permits multiplane viewing and eliminates the geometric distortions present in acoustical holography.
Changes in the Intensity and Pleasantness of Human Vaginal Odors During the Menstrual Cycle
Authors: Doty Richard L. , Ford Mary , Preti George , Huggins George R.
Published: October 2006

Men and women estimated (by the method of magnitude estimation) the pleasantness and intensity of the odors of vaginal secretions sampled from consecutive phases of 15 ovulatory menstrual cycles of four women. On the average, secretions from preovulatory and ovulatory phases were slightly weaker and less unpleasant in odor than those from menstrual, early luteal, and late luteal phases. However, considerable variation in odor patterns was present across cycles from the same donor, as well as across cycles from different donors. These results indicate that human vaginal odors change slightly in both pleasantness and intensity during the menstrual cycle, but do not support the notion that such odors are particularly attractive to humans in an in vitro test situation.
Rapid Oral Mixing of Glucose and Saccharin by Rats
Authors: Smith James C. , Williams Diane P. , Jue Sally Short
Published: October 2006

Within 5 minutes after initial contact rats show excessive consumption of a mixture of saccharin and glucose solutions. With a glucose solution in one bottle and the saccharin solution in another, a combination of which matches the above mixture, the rats also show large intakes. The pattern of drinking from the glucose and the saccharin bottles indicates that the rat mixes the solutions in rapid order, producing the preferred concentration of saccharin and glucose.
Perceptual Illusion of Rotation of Three-Dimensional Objects
Authors: Shepard Roger N. , Judd Sherryl A.
Published: October 2006

Perspective views of the same three-dimensional object in two orientations, when presented in alternation, produced an illusion of rigid rotation. The minimum cycle duration required for the illusion increased linearly with the angular difference between the orientations and at the same slope for rotations in depth and in the picture plane.
Mechanism of DNA Strand Transfer Reactions Catalyzed by HIV-1 Reverse Transcriptase
Authors: Peliska James A. , Benkovic Stephen J.
Published: October 2006

Two DNA strand transfer reactions occur during retroviral reverse transcription. The mechanism of the first, minus strand strong-stop DNA, transfer has been studied in vitro with human immunodeficiency virus 1 reverse transcriptase (HIV-1 RT) and a model template-primer system derived from the HIV-1 genome. The results reveal that HIV-1 RT alone can catalyze DNA strand transfer reactions. Two kinetically distinct ribonuclease (RNase) H activities associated with HIV-1 RT are required for removal of RNA fragments annealed to the nascent DNA strand. Examination of the binding of DNA⋅RNA duplex and single-stranded RNA to HIV-1 RT during strand transfer supports a model where the enzyme accommodates both the acceptor RNA template and the nascent DNA strand before the transfer event is completed. The polymerase activity incorporated additional bases beyond the 5′ end of the RNA template, resulting in a base misincorporation upon DNA strand transfer. Such a process occurring in vivo during retroviral homologous recombination could contribute to the hypermutability of the HIV-1 genome.
Antisense and Antigene Properties of Peptide Nucleic Acids
Authors: Hanvey Jeffery C. , Peffer Nancy J. , Bisi John E. , Thomson Stephen A. , Cadilla Rodolfo , Josey John A. , Ricca Daniel J. , Hassman C. Fred , Bonham Michele A. , Au Karin G. , Carter Stephen G. , Bruckenstein David A. , Boyd Ann L. , Noble Stewart A. , Babiss Lee E.
Published: October 2006

Peptide nucleic acids (PNAs) are polyamide oligomers that can strand invade duplex DNA, causing displacement of one DNA strand and formation of a D-loop. Binding of either a T
10
PNA or a mixed sequence 15-mer PNA to the transcribed strand of a G-free transcription cassette caused 90 to 100 percent site-specific termination of pol II transcription elongation. When a T
10
PNA was bound on the nontranscribed strand, site-specific inhibition never exceeded 50 percent. Binding of PNAs to RNA resulted in site-specific termination of both reverse transcription and in vitro translation, precisely at the position of the PNA ⋅ RNA heteroduplex. Nuclear microinjection of cells constitutively expressing SV40 large T antigen (T Ag) with either a 15-mer or 20-mer PNA targeted to the T Ag messenger RNA suppressed T Ag expression. This effect was specific in that there was no reduction in β-galactosidase expression from a coinjected expression vector and no inhibition of T Ag expression after microinjection of a 10-mer PNA.
Amelioration of Autoimmune Encephalomyelitis by Myelin Basic Protein Synthetic Peptide-Induced Anergy
Authors: Gaur Amitabh , Wiers Brook , Liu Angela , Rothbard Jonathan , Fathman C. Garrison
Published: October 2006

Experimental autoimmune encephalomyelitis (EAE), a demyelinating disease of the central nervous system that can be induced in susceptible strains of mice by immunization with myelin basic protein (MBP) or its immunodominant T cell determinants, serves as a model of human multiple sclerosis. Tolerance to MBP in adult mice was induced by intraperitoneal injection of synthetic peptides of immunodominant determinants of MBP and prevented MBP-induced EAE. Furthermore, tolerance-inducing regimens of peptides administered to mice after the disease had begun (10 days after induction with MBP) blocked the progression and decreased the severity of EAE. Peptide-induced tolerance resulted from the induction of anergy in proliferative, antigen-specific T cells.
Genetic and Somatic Effects of Carbon-14
Authors: Pauling Linus
Published: October 2006

On the basis of information about carbon-14 given by Libby, calculations are made of the predicted genetic and somatic effects of the carbon-14 produced by the testing of nuclear weapons. It is concluded that 1 year of testing (30 megatons of fission plus fusion) is expected to cause in the world (estimated future number of births per year 5 times the present number) an estimated total of about 55,000 children with gross physical or mental defects, 170,000 stillbirths and childhood deaths, and 425,000 embryonic and neonatal deaths. (There is an unknown amount of overlap of these three categories.) These numbers are about 17 times the numbers usually estimated as the probable effects of the fallout fission products from 1 year of testing. In addition, the somatic effects of bomb-test carbon-14 are expected to be about equal to those of fission products, including strontium-90, with respect to leukemia and bone cancer and greater than those of fission products with respect to diseases resulting from radiation damage to tissues other than bone tissue and bone marrow. All of the estimated numbers are subject to great uncertainty; they may be as much as 5 times too high or 5 times too low. The uncertainty in the estimation of the relative effects of carbon-14 and fission products in world-wide fallout is not so great.
Fractional Escape and Avoidance on a Titration Schedule
Authors: Weiss Bernard , Laties Victor G.
Published: October 2006

Rats were shocked, continuously or intermittently, by an electrical stimulus whose intensity increased by one step every 20 seconds. Each time the rat depressed a lever in the experimental chamber, shock intensity was decreased by one step. Lever-pressing was maintained on such a program, with both continuous and intermittent delivery of shock.
Geochemical Scavenging of Strontium
Authors: Frondel Clifford
Published: October 2006

Crandallite, an abundant mineral belonging to the alunite structure type, is a geochemical host for ordinary strontium in the soil profile and the deeper ground-water circulation. It may be useful in the scavenging or storage of the radioisotopes of strontium and certain other elements.
Inferior Olive: Its Role in Motor Learning
Authors: Llinás Rodolfo , Walton Kerry , Hillman Dean E. , Sotelo Constantino
Published: October 2006

Specific chemical lesion of the rat inferior olive by intraperitoneal administration of 3-acetylpyridine prevents recuperation from motor abnormalities generated by unilateral labyrinthine lesion. Moreover, in animals that have recuperated from the labyrinthine lesion, 3-acetylpyridine produces a reversal of the symptoms within 2 hours of administration. These results indicate that the integrity of the olivo-cerebellar system is necessary for the acquisition and retention of this form of motor learning, but that the cerebellum itself is not the seat of such learning.
Antigens and Antibodies as Cell Phenotypes
Authors: Schultz Jack
Published: October 2006

The paradoxical features of transplantation specificity—its strict genetic control in transfers of tissue from strain to strain as compared with its malleability on tissue passage in foreign immunological environments where the host does not reject the implant (F
1
hybrid passage, tolerance actively acquired by immature hosts, and so on)—present a challenge to genetic interpretation. The attempt is made in this article to show parallels between this behavior and such changes as the transformation of serotypes in
Paramecium
, in which the activity of genetic units becomes fixed as a cytoplasmic state—a cellular heredity persistent under specified environmental conditions but capable of change to an alternative state—while the genetic structure of the cell remains constant. The reactions appear to differ from those in the
Paramecium
case in that the diverse loci control a mosaic of different specificities, which change relatively independently of each other, in contrast to mutual exclusion of cytoplasmic states influenced by the different loci in
Paramecium
.

The process of antibody formation is considered as a change in cellular phenotype from the same point of view. The primary response in the stem cells of the lymphoid tissues is interpretable as the establishment of a new cytoplasmic state in response to a nuclear stimulus by the foreign antigen. For the secondary response, the suggestion is made that a reaction of antigen with cellular antibody at the surface of stem cells exhibiting the primary response serves as the stimulus for specific proliferation of antibody-forming clones of cells. A parallel is drawn with the fertilization reaction, specifically with regard to the initiation of cleavage in eggs by antisera to them.

Finally, a general chromosomal mechanism is sought for these phenomena, on the basis of activities of specific chromosome regions in response to special developmental stimuli, such as the disproportionate local synthesis of deoxyribonucleic acid demonstrated in the giant chromosomes of the Diptera. By a correlation of such activities with the nucleocytoplasmic system of ribonucleic acid granules on membranes, a possible mechanism appears for the formation, in response to environmental stimuli, of cytoplasmic states which might supply the persistent pattern required for this type of cell heredity. The analogies made, it is believed, provide a framework for the design of test experiments.
Paper Coal in Indiana
Authors: Guennel G. K. , Neavel Richard C.
Published: October 2006

The foliated, papery texture of the upper third of an 18-inch coal seam in a strip mine near Rockville, Indiana, is attributable to matted plant cuticle. The cuticles of pinnules, pinnae, and rachides resemble
Sphenopteris bradfordii
Arnold and thus differ from the lycopsid stem cuticles of the Russian paper coal.
Spectrum of Venus in the Violet and Near-Ultraviolet
Authors: Heyden F. J. , Kiess C. C. , Kiess Harriet K.
Published: October 2006

Recent observations of the spectrum of the planet Venus, with spectrographs of low and high dispersion at the Georgetown College Observatory, show that a wide, continuous absorption band is present in the violet and near-ultraviolet. The band begins near wavelength 4500 A and extends to the short-wavelength limit of our spectrograms near 3800 A. It is similar in structure to the strong absorption, reported by others, for gaseous nitrogen tetroxide.
Enzymatic Basis of Mannose Toxicity in Honey Bees
Authors: Sols Alberto , Cadenas Eduardo , Alvarado Francisco
Published: October 2006

Honey bees have a negligible amount of phosphomannoseisomerase, together with a high content of a hexokinase which phosphorylates mannose more efficiently than fructose or glucose. Competition at the phosphorylation level plus accumulation of mannose-6-phosphate can fully account for the toxicity of mannose in honey bees.