bluuebunny/crossref_metadata_2025 huggingface dataset:
Ganglioside Treatment of Streptozotocin‐Diabetic Rats Prevents Defective Axonal Transport of 6‐Phosphofructokinase Activity
Authors: Calcutt N. A. , Tomlinson D. R. , Willars G. B.
Published: October 2006

Abstract: This study measured axonal transport of 6‐phosphofructokinase (PFK) and aldolase activities in the sciatic nerves of rats with short‐term streptozotocin‐induced diabetes. The diabetic rats showed deficits in anterograde (69% of controls; p < 0.001) and retrograde (33% of controls; p < 0.01) accumulations of PFK activity as well as its content per unit length of unconstricted sciatic nerve (86% of controls; p < 0.05). There were no accumulation deficits in aldolase activity in the nerves of the diabetic rats, although the activity per unit length of unconstricted nerve was deficient (81% of controls; p < 0.05). Treatment of diabetic rats with mixed bovine brain gangliosides (10 mg/kg of body weight/day, i.p.) did not affect the deficit in PFK activity in unconstricted nerve (84% of ganglioside‐treated controls; p < 0.01), but all the other defects in enzyme activities were prevented completely. The diabetic rats also showed a reduction of 7% (p < 0.01) in sciatic nerve dry weight per unit length, which was prevented by ganglioside treatment. In contrast, the reduced motor nerve conduction velocity, accumulation of polyol pathway metabolites, and depletion of myo‐inositol. characteristic of untreated short‐term diabetes, were unaffected by ganglioside treatment.
Formation of the Neurotransmitter Glycine from the Anticonvulsant Milacemide Is Mediated by Brain Monoamine Oxidase B
Authors: de Varebeke Philippe Janssens , Cavalier Robert , David‐Remacle Michèle , Youdim Moussa B. H.
Published: October 2006

Abstract: Milacemide (2‐n‐pentylaminoacetamide) is a secondary monoamine that in the brain is converted to glycinamide and glycine. This oxidative reaction was suspected to involve the reaction of monoamine oxidase (MAO). Using mitochondrial preparations from tissues that contain MAO‐A and ‐B (rat brain and liver), MAO‐A (human placenta), and MAO‐B (human platelet and bovine adrenal chromaffin cell), it has been established that mitochondria containing MAO‐B rather than MAO‐A oxidize (H2O2 production and glycinamide formation) milacemide. The apparent Km (30–90 μM) for milacemide oxidation by mitochondrial MAO‐B preparations is significantly lower than that for milacemide oxidation by mitochondrial MAO‐A (approximately 1.300 μM). In vitro MAO‐B (/‐deprenyl and AGN 1135) rather than MAO‐A (clorgyline) selectively inhibited the oxidation of milacemide. These in vitro data are matched by ex vivo experiments where milacemide oxidation was compared to oxidation of serotonin (MAO‐A) and β‐phenylethylamine (MAO‐B) by brain mitochondria prepared from rats pre‐treated with clorgyline (0.5–10 mg/kg) and /‐deprenyl (0.5–10 mg/kg). Furthermore in vivo experiment demonstrated that /‐deprenyl selectively increased the urinary excretion of [14C]milacemide and the total radioactivity with a concomitant decrease of [14C]glycinamide. Such changes were not observed after clorgyline treatment, but were evident only at doses beyond clorgyline selectivity. The present data therefore demonstrate that milacemide is a substrate for brain MAO‐B, and its conversion to glycinamide, further transformed to the inhibitory neurotransmitter, glycine, mediated by this enzyme may contribute to its pharmacological activities.
Effects of Systemic Administration of 1‐Methyl‐4‐Phenyl‐1,2,3,6‐Tetrahydropyridine to Mice on Tyrosine Hydroxylase, l‐3,4‐Dihydroxyphenylalanine Decarboxylase, Dopamine β‐Hydroxylase, and Monoamine Oxidase Activities in the Striatum and Hypothalamus
Authors: Mogi Makio , Harada Minoru , Kojima Kohichi , Kiuchi Kazutoshi , Nagatsu Toshiharu
Published: October 2006

Abstract: The effects of 1‐methyl‐4‐phenyl‐l,2,3,6‐tetrahydropyridine (MPTP) (30 mg/kg subcutaneously per day for 8 days) to C57BL/6N mice were studied on tyrosine hydroxylase (TH), l‐3,4‐dihydroxyphenylalanine decarboxylase (DDC), and monoamine oxidase (MAO) activities in the striatum, and TH, DDC, dopamine‐β‐hydroxylase (DBH), and MAO activities in the hypothalamus. Treatment with MPTP led to a large decrease in TH activity and a parallel decrease in DDC activity in the striatum, as compared with the saline controls. In contrast, MPTP administration did not cause a decrease of the activities of TH, DDC, and DBH in the hypothalamus. There was also no reduction in MAO activities of striatum and hypothalamus. These data indicate that MPTP administration to mice results in specific degeneration of the dopaminergic nigrostriatal pathway and that DDC in the mouse striatum may mainly be localized in the dopaminergic neurons with TH.
Effect of Lithium and of Other Drugs Used in the Treatment of Manic Illness on the Cation‐Transporting Properties of Na+, K+‐ATPase in Mouse Brain Synaptosomes
Authors: Wood A. J. , Elphick M. , Grahame‐Smith D. G.
Published: October 2006

Abstract We have developed and used a novel technique to investigate the effects of lithium and other psychotropic drugs on the cation‐transporting properties of the sodium‐ and potassium‐activated ATPase enzyme (Na+, K+‐ATPase) in intact synaptosomes. Rubidium‐86 uptake into intact synaptosomes is an active process and is inhibited by ∼75% in the presence of the Na+, K+‐ATPase inhibitor acetylstrophanthidin. In vitro addition of lithium to synaptosomes prepared from untreated mice causes a progressive inhibition of acetylstrophanthidin‐sensitive 86Rb uptake, but only at concentrations higher than the clinical therapeutic range. However, pretreatment of mice for 14 days in vivo with lithium, carbamazepine, and haloperidol, but not phenytoin, causes a significant stimulation of 86Rb uptake into synaptosomes via Na+, K+‐ATPase.
ATP‐Evoked Ca2+ Mobilisation and Prostanoid Release from Astrocytes: P2‐Purinergic Receptors Linked to Phosphoinositide Hydrolysis
Authors: Pearce Brian , Murphy Sean , Jeremy James , Morrow Christine , Dandona Paresh
Published: October 2006

Abstract: Astrocyte cultures prelabelled with either [3H]‐inositol or 45Ca2+ were exposed to ATP and its hydrolysis products. ATP and ADP, but not AMP and adenosine, produced increases in the accumulation of intracellular 3H‐labelled inositol phosphates (IP), efflux of 45Ca2+, and release of thromboxane A2 (TXA2). Whereas ATP‐stimulated 3H‐IP accumulation was unaffected, its ability to promote TXA2 release was markedly reduced by mepacrine, an inhibitor of phospholipase A2 (PLA2). ATP‐evoked 3H‐IP production was also spared following treatment with the cyclooxygenase inhibitor, indomethacin. We conclude that ATP‐induced phosphoinositide (PPI) breakdown and 45Ca2+ mobilisation occurred in parallel with, if not preceded, the release of TXA2. Following depletion of intracellular Ca2+ with a brief preexposure to ATP in the absence of extracellular Ca2+, the release of TXA2 in response to a subsequent ATP challenge was greatly reduced when compared with control. These results suggest that mobilisation of cytosolic Ca2+ may be the stimulus for PLA2 activation and, thus, TXA2 release. Stimulation of α‐adrenoceptors also caused PPI breakdown and 45Ca2+ efflux but not TXA2 release. The effects of ATP and noradrenaline (NA) on 3H‐IP accumulation were additive, but their combined ability to increase 45Ca2+ efflux was not. Interestingly, in the presence of NA, ATP‐stimulated TXA2 release was reduced. Our data provide evidence that functional P2‐purinergic receptors are present on astrocytes and that ATP is the first physiologically relevant stimulus found to initiate prostanoid release from these cells.
Pharmacological and Functional Heterogeneity of Astrocytes: Regional Differences in Phospholipase C Stimulation by Neuromediators
Authors: El‐Etr M. , Cordier J. , Torrens Y. , Glowinski J. , Prémont J.
Published: October 2006

Abstract: Carbamylcholine stimulated phospholipase C activity in astrocytes in primary culture from the mesencephalon but not from the striatum or cerebral cortex of the mouse embryo. An α1‐adrenergic‐mediated response was observed in all astrocyte populations. 2‐Chloroadenosine potentiated the α1‐adrenergic response in mesencephalic and striatal astrocytes but not in cortical astrocytes. It also stimulated the carbamylcholine‐evoked response in mesencephalic astrocytes. Through cell‐cell cooperation, 2‐chloroadenosine potentiated the neuronal carbamylcholine‐evoked activation of phospholipase C in homotopic cocultures (neuroglial) from the striatum but not in homotopic cocultures (neuroglial) from the cerebral cortex or in heterotopic cocultures (cortical astrocytes‐striatal neurons; striatal astrocytes‐cortical neurons).
Stimulation of D‐2 Dopamine Receptors Decreases the Evoked In Vitro Release of [3H] Acetylcholine from Rat Neostriatum: Role of K+ and Ca2+
Authors: Drukarch B. , Schepens E. , Schoffelmeer A. N. M. , Stoof J. C.
Published: October 2006

Abstract: Reportedly, stimulation of D‐2 dopamine receptors inhibits the depolarization‐induced release of acetylcholine from the neostriatum in a cyclic AMP‐independent manner. In the present study, we investigated the role of K+ and Ca2+ in the D‐2 receptor‐mediated inhibition of evoked [3H]acetylcholine release from rat striatal tissue slices. It is shown that the D‐2 receptor‐mediated decrease of K+‐evoked [3H]acetylcholine release is not influenced by the extracellular Ca2+ concentration. However, increasing extracellular K+, in the presence and absence of Ca2+, markedly attenuates the effect of D‐2 stimulation on the K+‐evoked [3H]acetylcholine release. Furthermore, it is shown that activation of D‐2 receptors in the absence of Ca2+ also inhibits the veratrine‐evoked release of [3H]acetylcholine from rat striatum. These results suggest that the D‐2 dopamine receptor mediates the decrease of depolarization‐induced [3H]acetylcholine release from rat striatum primarily by stimulation of K+ efflux (opening of K+ channels) and inhibition of intracellular Ca2+ mobilization.
Biosynthesis, Development, and Regulation of Neuropeptide Y in Superior Cervical Ganglion Culture
Authors: Marek Kenneth L. , Mains Richard E.
Published: October 2006

Abstract: The biosynthesis of neuropeptide Y (NPY) and norepinephrine (NE) has been examined in dissociated neuronal cultures from newborn rat superior cervical ganglion (SCG). NPY synthetic rate was measured by immunoprecipitation and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis after incubation in medium containing a labeled amino acid. The authenticity of the NPY was confirmed by reverse‐phase HPLC analyses of tryptic peptides. The NPY synthetic rate in cultures grown in complete serum free medium increased 30‐fold after plating, in parallel to catecholamine synthesis; both NPY and the catecholamines reached the rate for adult SCG neurons. This development in culture is seen without spinal cord input, target organs, or significant numbers of glial cells. NPY synthesis was maintained in the face of a major decrease in the rate of NE production after cholinergic induction.
Formal Demonstration of the Phosphorylation of Rat Brain Tryptophan Hydroxylase by Ca2+/Calmodulin‐Dependent Protein Kinase
Authors: Ehret Mireille , Cash Christopher D. , Hamon Michel , Maitre Michel
Published: October 2006

Abstract: Tryptophan hydroxylase is activated in a crude extract by addition of ATP and Mg2+. This activation is reversible and requires in addition both Ca2+ and calmodulin. Thus, phosphorylation by an endogenous calmodulin‐dependent protein kinase has long been suspected. Now that we have prepared a specific polyclonal antibody to rat brain tryptophan hydroxylase, we have been able to prove that this hypothesis is correct. After incubation of purified tryptophan hydroxylase with Ca2+/calmodulin‐dependent protein kinase together with [γ‐32P]ATP, Mg2+, Ca2+, and calmodulin, followed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and blotting of the enzymes onto nitrocellulose sheets, we could label the band of tryptophan hydroxylase by the antiserum and the peroxidase technique and show by autoradiography that 32P was incorporated into this band. By measuring the radioactivity, we calculated that about 1 mol of phosphate was incorporated per 8 mol of subunits of the enzyme (2 mol of native enzyme). Because the concentration of ATP which we employed (50μM) gives about half‐maximal activation in crude extract compared to saturating ATP conditions (about 1 mM), this result indicates that the incorporation of at least 1 mol of phosphate/mol of tetramer of native tryptophan hydroxylase is required for maximal activation.
Modification of Gs‐Stimulated Adenylate Cyclase in Brain Membranes by Low pH Pretreatment: Correlation with Altered Guanine Nucleotide Exchange
Authors: Rasenick Mark M. , Childers Steven R.
Published: October 2006

Abstract: Pretreatment of rat brain membranes at pH 4.5 before assay at pH 7.4 modifies the function of GTP‐binding proteins (G‐proteins) by eliminating Gs‐stimulated adenylate cyclase activity while increasing opiate‐inhibited adenylate cyclase activity. To help characterize the molecular nature of the low pH effect, we labeled Gs and Gi a‐subunits in both control and low pH‐pretreated membranes with the GTP photoaffinity analog [32P]P3(4‐azidoanilido)‐P1‐5′‐GTP ([32P]AAGTP). When membranes were preincubated with unlabeled AAGTP, a persistent inhibitory state of adenylate cyclase was produced, which was overcome in untreated membranes with high (< 1 μM) concentrations of guanylyl‐5′‐imidodiphosphate [Gpp(NH)p]. In low pH‐pretreated membranes, this inhibition could not be overcome, and stimulation by Gpp(NH)p was eliminated. Maximal inhibition of adenylate cyclase achieved by incubation with AAGTP was not altered by low pH pretreatment. Incorporation of [32P]AAGTP into Gs (42 kilodaltons) or Gi/G (40 kilodaltons) was unaffected by low pH pretreatment; however, transfer of 32P from Gi/o to Gs, which occurs with low (10 nM) concentrations of Gpp(NH)p in untreated membranes, was severely retarded in low pH‐pretreated membranes. Both the potency and efficacy of Gpp(NH)p in producing exchange of [32P]AAGTP from Gi/0 to Gs were markedly reduced by low pH pretreatment. These results correlate the loss of Gs‐stimulated adenylate cyclase with a loss of transfer of nucleotide from Gi/0 to Gsα‐subunits and suggest that the nucleotide exchange participates in the modulation of neuronal adenylate cyclase.
The Novel Neuropsychotropic Agent Milacemide Is a Specific Enzyme‐Activated Inhibitor of Brain Monoamine Oxidase B
Authors: de Varebeke Philippe Janssens , Pauwels Gilbert , Buyse Corinne , David‐Remacle Michele , Mey Jo De , Roba Josd , Youdim Moussa B. H.
Published: October 2006

Abstract: The novel neuropsychotropic agent milacemide hydrochloride (2‐n‐pentylaminoacetamide HCl) is a highly selective substrate of the B form of monoamine oxidase (EC 1.4.3.4; MAO). Under the in vitro conditions used in the present study, milacemide acts as an enzyme‐activated, par‐tially reversible inhibitor of MAO‐B. A reversible inhibition of MAO‐A activity is also observed at high concentrations. The inhibitory activity of milacemide is significantly greater for MAO‐B. In vivo, after single or repeated oral administration, a specific inhibition of MAO‐B is apparent in brain and liver, with a lack of inhibition of the MAO‐A Activity. In contrast to the irreversible inhibitory action of L‐deprenyl, the recovery of MAO‐B activity in vivo after milacemide administration is significantly faster, a result suggesting that it is a partially reversible inhibitor. The selective inhibitory effect of milacemide for MAO‐B in vivo is confirmed by its potentiation of phenylethylamine‐induced stereotyped behavior, whereas vasopressor responses to tyramine were not affected. These observations suggest that milacemide could enhance dopaminergic activity in the brain and could be used as therapy for Parkinson's disease in association with L‐3,4‐dihydroxyphenylalanine.
Actions of Excitatory Amino Acids on Somatostatin Release from Cortical Neurons in Primary Cultures
Authors: Tapia‐Arancibia Lucia , Astier Helene
Published: October 2006

Abstract: L‐Glutamate, N‐methyl‐D‐aspartic acid (NMDA), quisqualate, and kainate were found to increase endogenous somatostatin release from primary cultures of rat cortical neurons in a dose‐dependent manner. The rank order of potency calculated from the dose‐response curves was quisqualate > glutamate = NMDA > kainate, with EC50 values of 0.4, 20, and 40 μM, respectively. Alanine, glutamine, and glycine did not modify the release of somatostatin. The stimulation of somatostatin release elicited by L‐glutamate was Ca2+ dependent, was decreased by Mg2+, and was blocked by DL‐amino‐5‐phosphonovaleric acid (APV) and thienyl‐phencyclidine (TCP), two specific antagonists of NMDA receptors. The NMDA stimulatory effect was strongly inhibited by APV in a competitive manner (IC50= 50 μM) and by TCP in a noncompetitive manner (IC50= 90 nM). The release of somatostatin induced by the excitatory amino acid agonists was not blocked by tetrodotoxin (1 μM), a result suggesting that tetrodotoxin‐sensitive, sodium‐dependent action potentials are not involved in the effect. Somatostatin release in response to NMDA was potentiated by glycine, but the inhibitory strychnine‐sensitive glycine receptor did not appear to be involved. Our data suggest that glutamate exerts its stimulatory action on somatostatin release essentially through an NMDA receptor subtype.
Protein Phosphorylation in Astrocytes Mediated by Protein Kinase C: Comparison with Phosphorylation by Cyclic AMP‐Dependent Protein Kinase
Authors: Harrison Beth C. , Mobley Philip L.
Published: October 2006

Abstract: The protein kinase C activator, phorbol 12‐myris‐tate 13‐acetate (PMA), has been found recently to transform cultured astrocytes from flat, polygonal cells into stellate‐shaped, process‐bearing cells. Studies were conducted to determine the effect of PMA on protein phosphorylation in astrocytes and to compare this pattern of phosphorylation with that elicited by dibutyryl cyclic AMP (dbcAMP), an activator of the cyclic AMP‐dependent protein kinase which also affects astrocyte morphology. Exposure to PMA increased the amount of32P incorporation into several phosphoproteins, including two cytosolic proteins with molecular weights of 30,000 (pI 5.5 and 5.7), an acidic 80,000 molecular weight protein (pI 4.5) present in both the cytosolic and membrane fractions, and two cytoskeletal proteins with molecular weights of 60,000 (pI 5.3) and 55,000 (pI 5.6), identified as vimentin and glial fibrillary acidic protein, respectively. Effects of PMA on protein phosphorylation were not observed in cells depleted of protein kinase C. In contrast to the effect observed with PMA, treatment with dbcAMP decreased the amount of 32P incorporation into the 80,000 protein. Like PMA, treatment with dbcAMP increased the 32P incorporation into the proteins with molecular weights of 60,000, 55,000 and 30,000, although the magnitude of this effect was different. The effect of dbcAMP on protein phosphorylation was still observed in cells depleted of protein kinase C. The results suggest that PMA, via the activation of protein kinase C, can alter the phosphorylation of a number of proteins in astrocytes, and some of these same phosphoproteins are also phosphorylated by the cyclic AMP‐dependent mechanisms.
Carrier‐Mediated Transport of Thyroid Hormones into Rat Glial Cells in Primary Culture
Authors: Francon Jacques , Chantoux Françoise , Blondeau Jean‐Paul
Published: October 2006

Abstract: The uptake of 3,3′,5‐[3′‐125I]triiodo‐L‐thyronine ([125I]L‐T3) and of L‐[3′,5′‐125I]thyroxine ([125I]L‐T4) by cultured rat glial cells was studied under initial velocity (Vi) conditions. Uptake of both hormones was carrier mediated and obeyed simple Michaelis‐Menten kinetics. The following respective values of Km (μM) and Vmax (fmol/min/μg of DNA) were obtained at 25°C: 0.52 ± 0.09 and 727 ± 55 for L‐T3 and 1.02 ± 0.21 and 690 ± 85 for L‐T4. Ki values (μM) for the inhibition of [125I]L‐T3 uptake by unlabeled analogues were as follows: L‐T4, 0.88; 3,3′,5′‐triiodo‐L‐thyronine, 1.4; 3,3′‐diiodo‐L‐thyronine, 2.9; 3,3′,5‐triiodo‐D‐thyronine, 4.8; and triiodothyroacetic acid, 5.3. These values indicate that the uptake system is stereospecific. Unlabeled L‐T3 was a better competitor than unlabeled L‐T4 for the uptake of [l25l]L‐T4, an observation suggesting that both hormones were taken up by a common carrier system. L‐T3 and L‐T4 uptake was pH dependent, a finding suggesting that the phenolic unionized form of the hormones was preferentially taken up. L‐T3 uptake was studied in the presence of various inhibitors; the results suggest that uptake was independent of the transmembrane Na+ gradient and of the cellular energy. Compounds that inhibited cellular uptake but were without effect on L‐T3 binding to isolated nuclei also inhibited L‐T3 nuclear binding in intact cells, an observation suggesting that uptake could be rate limiting for the access of L‐T3 to nuclear receptors when transport is severely inhibited.
Chronic Exposure of NG 108‐15 Cells to Opiate Agonists Does Not Alter the Amount of the Guanine Nucleotide‐Binding Proteins Gi and GO
Authors: Lang J. , Costa T.
Published: October 2006

Abstract: We have characterized the pertussis toxin substrate in NG 108–15 cell membranes using site‐specific antisera and ADP‐ribosylation. Cell membranes contain two pertussis toxin‐sensitive guanine nucleotide‐binding protein α‐subunits (Gα) whose Rf values in gel electrophoresis coincide with those of Gαo and Gαi2. The total quantity of Gi and Go im‐munoreactivity amounted to 24.3 ± 2.8 pmol/mg, whereas only 1.5 ± 0.2 pmol/mg are capable of undergoing ADP‐ribosylation catalyzed by pertussis toxin. Pretreatment of cells with the agonist [D‐Ala2,D‐Leu2]‐enkephalin (DADLE) for 24 h and DADLE or morphine for 72 h did not alter the incorporation of ADP‐ribose or the immunoreactive amount of Gi and Go subunits. However, pretreatment for 72 h with naloxone increased the incorporation of ADP‐ribose without an apparent change in affinity or in the immunochemically determined protein levels of Gi and Go. This indicates that the process of down‐regulation and desensitization of the γ‐opioid receptor neither requires quantitative alterations in the levels of Gi and Go nor changes in the degree of coupling among their subunits. In contrast, chronic exposure to antagonists seems to alter the degree of precoupling between α‐and β‐subunits of Gi and/or Go.
Purification and Characterization of Neutral and Acid Sphingomyelinases from Rat Brain
Authors: Maruyama Etsuko Noguchi , Arima Masataka
Published: October 2006

Abstract: Neutral and acid sphingomyelinases were copurified from a rat brain P2 fraction by extraction with 1% Triton X‐100, followed by (NH4)2SO4 fractionation, acetone powdering, extraction with 1% Triton X‐100, (NH4)2SO4 fractionation, Sepharose CL‐6B chromatography, and chromatofocusing. The neutral sphingomyelinase was eluted with buffer containing 0.4 M NaCl after the acid sphingomyelinase had been eluted with Polybuffer at pH 5.3. The neutral sphingomyelinase exhibited specific activity of 48,300 nmol/h/mg of protein, with 254‐fold purification; the corresponding value for acid sphingomyelinase was 25,300 nmol/h/mg protein, with 668‐fold purification from the P2 fraction. The purified neutral sphingomyelinase had no acid sphingomyelinase activity, and vice versa. The properties of the two enzymes were examined. A single band corresponding to a molecular weight of 67,000 was obtained on sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) for both enzymes. The pI was estimated to be 5.5 for both on isoelectric focusing. The native molecular weights of the neutral and acid sphingomyelinases were found to be 434,000 and 284,000, respectively, on gel filtration with Sepharose CL‐6B. The single band obtained for each enzyme on SDS‐PAGE was identified as an antigen with antibody raised against the purified neutral sphingomyelinase. Their amino acid compositions were very similar. The neutral and acid sphingomyelinases probably consist of common polypeptides and are immunologically cross‐reactive.
Oxidation of Analogs of l‐Methyl‐4‐Phenyl‐1,2,3,6‐Tetrahydropyridine by Monoamine Oxidases A and B and the Inhibition of Monoamine Oxidases by the Oxidation Products
Authors: Youngster Stephen K. , McKeown Kathleen A. , Jin Yuan‐Zhen , Ramsay Rona R. , Heikkila Richard E. , Singer Thomas P.
Published: October 2006

Abstract: Twenty analogs of l‐methyl‐4‐phenyl‐l,2,3,6‐tet‐rahydropyridine (MPTP) were tested for their capacity to be xidized by pure monoamine oxidase‐A (MAO‐A) prepared from human placenta and pure monoamine oxidase‐B (MAO‐B) prepared from beef liver. Several of the MPTP analogs were very good substrates for MAO‐A, for MAO‐B, or for both and had low Km values and high turnover numbers. These values were similar to or even better than those of kynuramine and benzylamine, good substrates for MAO‐A and MAO‐B, respectively. MPTP had relatively low Km values for oxidation by both MAO‐A and MAO‐B. In contrast, the turnover number for MPTP oxidation by MAO‐B was considerably higher than the value for MAO‐A. The corresponding pyridinium species of MPTP and several of the MPTP analogs inhibited MAO‐A competitively with Ki values at micromolar concentrations; in contrast the pyridinium species inhibited MAO‐B competitively at considerably higher concentrations (i.e., 100 μM or greater Ki values). The data provide information concerning the structural requirements for the oxidation of tetrahydropyridines by MAO‐A and MAO‐B and the inhibition of these enzymes by pyridini‐ums
Molecular Size of the γ‐Aminobutyric AcidA Receptor Purified from Mammalian Cerebral Cortex
Authors: Mamalaki Cleanthi , Barnard Eric A. , Stephenson F. Anne
Published: October 2006

Abstract: The hydrodynamic behaviour of both the soluble and purified γ‐aminobutyric acidA (GABAA) receptor of bovine or rat cerebral cortex has been investigated in solution in Triton X‐100 or in 3‐[(3‐cholamidopropyl)‐dimethylammonio]‐1‐propanesulphonate (CHAPS). In all the hydrodynamic separations made, it was found that the binding activities for GABA, benzodiazepine, and (where detectable) t‐butylbicyclophosphorothionate comigrated. Conditions were established for gel exclusion chromatography and for sucrose density gradient velocity sedimentation that maintain the GABAA receptor in a nonaggregated form. Using these conditions, the molecular weight of the bovine GABAA receptor in the above‐mentioned detergents was calculated using the H2O/2H2O method. A value of Mr 230,000–240,000 was calculated for the bovine pure GABAA receptor purified in sodium deoxycholate/Triton X‐100 media. A value of Mr 284,000–290,000 was calculated for the nonaggregated bovine or rat cortex receptor in CHAPS, but the Stokes radius is smaller in the latter than in the former medium and the detergent binding in CHAPS is underestimated. Thus the deduced Mr, 240,000, is the best estimate by this method.
Regulation of Muscarinic Agonist‐Induced Activation of Phosphoinositidase C in Electrically Permeabilized SH‐SY5Y Human Neuroblastoma Cells by Guanine Nucleotides
Authors: Wojcikiewicz Richard J. H. , Lambert David G. , Nahorski Stefan R.
Published: October 2006

myo‐[3H]Inositol‐labelled SH‐SY5Y cells were permeabilized with electrical discharges. 3H‐Inositol phosphate formation in cells shown to be fully permeable was stimulated by the muscarinic agonist carbachol, by guanosine 5′‐(γ‐thio)triphosphate [GTP(S)], and by guanosine 5′‐(β‐thio)diphosphate (GppNHp). Synergism was observed on coincubation of these GTP analogues with carbachol. GTP was also stimulatory and guanosine 5′‐(β‐thio)diphosphate was inhibitory in the presence of agonist. Atropine blocked the effects of carbachol. Stimulation by GTP(S) (0.1 mM) occurred after a 1‐2‐min lag, whereas Ca2+ (0.5 mM), carbachol (1 mM), and carbachol plus GTP(S) stimulated without delay. The effects of carbachol plus GTP(S) but not those of Ca2+ were inhibited by spermine (4 mM). Accumulation of 3H‐inositol phosphates was enhanced by Li+ (4 mM) only in intact cells. In intact or permeabilized cells, the “partial” agonist arecoline was maximally 40–50% as efficacious as carbachol. In permeabilized cells, the maximal effects of carbachol and arecoline were enhanced 2.8‐ and 5.3‐fold, respectively, by 0.1 mM GTP(S), but only the EC50 for carbachol was substantially reduced. The binding affinity of carbachol but not that of arecoline in permeabilized cells was significantly reduced by 0.1 mM GppNHp. These data indicate that a guanine nucleotide‐binding regulatory protein is involved in coupling muscarinic receptors to phosphoinositidase C in SH‐SY5Y cells and that the activity of this protein influences the relationship between receptor occupation and phosphoinositide response.
Detection of pemphigus desmoglein 1 and desmoglein 3 autoantibodies and pemphigoid BP180 autoantibodies in saliva and comparison with serum values
Authors: Andreadis Dimitrios , Lorenzini Guido , Drakoulakos Drakoulis , Belazi Maria , Mihailidou Euaggelia , Velkos Georgios , Mourellou‐Tsatsou Olga , Antoniades Demetrios
Published: October 2006

Although there is much literature on the detection of pemphigus and pemphigoid autoantibodies by enzyme‐linked immunosorbent assay (ELISA) in serum, nothing is known about their presence in saliva. The aim of this study was to evaluate the salivary levels of these autoantibodies in pemphigus and pemphigoid patients. Autoantibodies against desmoglein3, desmoglein1, and BP180 were assayed, by ELISA, in serum and saliva samples of patients and healthy controls. The titres of autoantibodies against Dsg1/3 found in both serum and saliva of pemphigus patients showed a statistically significant correlation, suggesting that saliva may be a useful biological material for diagnostic purposes, in monitoring disease activity, as well as for the early detection of relapses. By contrast, the titres of autoantibodies against BP180 in the serum and saliva of bullous pemphigoid patients were not statistically related, and further study of the usefulness of the BP180 ELISA for saliva in this disease is needed. In addition, based on our results, the BP180 ELISA with a recombinant NC16a epitope failed to detect the autoantibodies against BP180 in the serum and saliva of mucous membrane pemphigoid patients.
Boosting effect of bisphosphonates on osteoconductive materials: a histologic in vivo evaluation
Authors: Houshmand B. , Rahimi H. , Ghanavati F. , Alisadr A. , Eslami B.
Published: October 2006

Background and Objective:  The effect on bone regeneration, of adding pamidronate disodium to bovine‐derived hydroxyapatite, was histologically evaluated, using the sheep bone model.

Material and Methods:  Twenty‐four intrabony defects were prepared in the lower jaw of eight sheep using trephine 6 mm burs. One cavity was left unfilled and the other two were filled with bovine‐derived hydroxyapatite (BioOss™) alone (control group) or with bovine‐derived hydroxyapatite mixed with pamidronate disodium (Aredia) (case group), respectively. After 6 wk, the animals were killed and the coded samples observed using an optical microscope. The percentage of regenerated bone, number of osteoclasts and amount of inflammation was recorded. Statistical analysis was carried out using chi‐square and Mann–Whitney U‐tests.

Results:  The results manifested a significant difference in the amount of bone formation, with the most being observed in the case group and the least in the negative‐control group (p < 0.001). Significantly fewer osteoclasts were observed in the case group than in the other groups (p < 0.001). The amount of inflammation did not seem to differ within the case and control groups (p > 0.05).

Conclusion:  Adding pamidronate disodium to bovine‐derived hydroxyapatite improves its osteoconductive and regenerative specifications. Further study should determine the systemic effects of a single local administration of these drugs, and their appropriate dose and type, with minimal risk.
HLA Antigens and Corticosteroid Response
Authors: Becker Bernard , Shin Dong H. , Palmberg Paul F. , Waltman Stephen R.
Published: October 2006

Compared with normal individuals, patients with primary open-angle glaucoma have increased prevalences of HLA-B12 and B7 antigens and are more responsive to glucocorticoids. Lymphocytes from both ocular normotensive and glaucomatous individuals with the HLA-B12 antigen require significantly (
P
< .02) lower concentrations of prednisolone to inhibit phytohemagglutinin-induced transformation.
The Site of Action of DDT in the Cockroach
Authors: Roeder Kenneth D. , Weiant Elizabeth A.
Published: October 2006

(1) Although DDT undoubtedly affects motor nerves and muscle fibers in concentrations greater than 1,000 ppm, this action cannot be directly responsible for the clonic tremors in the DDT-poisoned cockroach which can be produced by internal concentrations of the order of 5 ppm.

(2) DDT has no significant action on the cockroach central nervous system.

(3) DDT emulsion perfused through the leg of the cockroach in concentrations as low as 0.01 ppm causes the appearance of a series of high frequency trains of axon spikes in the afferent fibers.

(4) It is concluded that the tremors characteristic of DDT poisoning are due to an intense afferent bombardment of the motor neurons.
Lesions of the Pancreatic Islets Produced in Cats by Administration of Glucose
Authors: Dohan F. C. , Lukens F. D. W.
Published: October 2006

Hydropic degeneration of the islands of Langerhans and permanent severe diabetes mellitus have followed the prolonged injection of intraperitoneal glucose-saline solution in normal as well as in partially depancreatized cats. Positive results were associated with prolonged hyperglycemia. These findings add further evidence in support of the hypothesis that a sustained elevation of blood glucose may, under certain conditions, lead to the production of damage to the islands of Langerhans in this species. Besides hyperglycemia, other disturbances which might be responsible wholly or in part for the island lesions are under study.
Differentiation of Red Blood Cells in Vitro
Authors: Broyles Robert H. , Deutsch Michael J.
Published: October 2006

Differentiation of red blood cells occurs in organ cultures of both liver and kidney tissue from tadpoles of the bullfrog
Rana catesbeiana
. Our evidence indicates that different red blood cell lines are produced by the two tissues and that these different cell lines contain different tadpole hemoglobins.
Binding of C-Reactive Protein to Antigen-Induced But Not Mitogen-Induced T Lymphoblasts
Authors: Croft S. M. , Mortensen R. F. , Gewurz H.
Published: October 2006

The C-reactive protein (CRP), an acute phase reactant which binds selectively to T (thymus-derived) lymphocytes, was found to bind to lymphoblasts formed upon stimulation with antigens but not with mitogens. Binding of CRP thus serves as a marker for antigen-reactive (-reacted) as opposed to mitogen-reactive (-reacted) T cells, suggesting that these represent separate subpopulations, and supports the developing concept that CRP plays an important role in the regulation of responses critical to inflammation, host defense, and tissue repair.
Complement-Mediated Bactericidal System: Evidence for a New Pathway of Complement Action
Authors: Moreau S. C. , Skarnes R. C.
Published: October 2006

The early components of human complement (C1, C4, and C2) plus certain serum euglobulins will kill pathogenic strains of
Shigella sonnei
. Serum from patients with hereditary C3 deficiencies and specific antiserums to C3, C5, and C6 were utilized to demonstrate the absence of requirements for late-acting complement components in this unusual bactericidal system.
Halogenated Hydrocarbons in New Orleans Drinking Water and Blood Plasma
Authors: Dowty Betty , Carlisle Douglas , Laseter John L. , Storer James
Published: October 2006

Volatile organics from New Orleans drinking water and pooled plasma were collected on a solid phenyl ether polymer and analyzed by gas chromatographic and mass spectrometric techniques. Thirteen halogenated hydrocarbons were identified in the drinking water. Five halogenated compounds were found in the plasma. Tetrachloroethylene and carbon tetrachloride were found in both the plasma and the drinking water. Considerable variation in the relative concentrations of the halogenated hydrocarbons was noted from day to day in the drinking water.
Self-Produced Locomotion Restores Visual Capacity After Striate Lesions
Authors: Dru Denise , Walker James Paul , Walker Judith Boas
Published: October 2006

Rats permitted unrestrained movement in a patterned visual environment during the interval between two-stage bilateral lesions of the visual cortex reacquire a preoperatively learned pattern discrimination. Rats passively transported through the identical visual environment do not. This is the first demonstration that interoperative self-produced locomotion is essential for recovery of function in the visual system.
Extreme Toxicity from Combustion Products of a Fire-Retarded Polyurethane Foam
Authors: Petajan J. H. , Voorhees K. J. , Packham S. C. , Baldwin R. C. , Einhorn I. N. , Grunnet M. L. , Dinger B. G. , Birky M. M.
Published: October 2006

The products from nonflaming combustion of wood and a trimethylolpropane-based rigid-urethane foam that was not fire-retarded produced elevated carboxyhemoglobin levels but no abnormal neurological effects. However, when this type of foam contained a reactive phosphate fire retardant, the combustion products caused grand mal seizures and death in rats. The toxic combustion product responsible for the seizures has been identified as 4-ethyl-1-phospha-2,6,7-trioxabicyclo(2.2.2.)octane-1-oxide.
Porphyrin Triplet State Probing the Diffusion of Oxygen in Hemoglobin
Authors: Alpert Bernard , Lindqvist Lars
Published: October 2006

Laser photolysis study of porphyrin-globin shows that the triplet state of the porphyrin is detectable by its light absorption and that it can be used to determine the rate of penetration of oxygen into the hemoglobin pocket in which the porphyrin is embedded. The oxygen penetration rate does not determine the binding rate of oxygen to iron in hemoglobin.
From
Whole Earth
to the Whole Web
Authors: Lieberman Henry
Published: October 2006

From Counterculture to Cyberculture
. Stewart Brand, the Whole Earth Network, and the Rise of Digital Utopianism.
By Fred Turner
. University of Chicago Press, Chicago, 2006. 353 pp. $29, £18.50. ISBN 9780226817415.

The author describes how interplay between cold war technology and hippie communalism led to the
Whole Earth Catalog
, the WELL,
Wired
, and the open world of the Internet.
Parasite Reproductive Strategy and Evolution of Castration of Hosts by Parasites
Authors: Obrebski Steven
Published: October 2006

A modification of the Euler equation is used to describe a simple parasite life history in which survival decreases with age at a rate determined by mortality of the parasitized host. The advantages of castration of hosts by parasites are discussed using the modified equation in which castration is equivalent to reducing parasite virulence in the host to near zero or zero. It is suggested that castrating parasites can infest a wider range of hosts with higher mortality rates and that within parasite groups having castrating and noncastrating species, the former should infest hosts with higher mortality rates and relatively larger gonads.
Microbial Trace-Fossil Formation, Biogenous, and Abiotic Weathering in the Antarctic Cold Desert
Authors: Friedmann E. Imre , Weed Rebecca
Published: October 2006

In the Antarctic cold desert (Ross Desert), the survival of the cryptoendolithic microorganisms that colonize the near-surface layer of porous sandstone rocks depends on a precarious equilibrium of biological and geological factors. An unfavorable shift of this equilibrium results in death, and this may be followed by formation of trace fossils that preserve the characteristic iron-leaching pattern caused by microbial activity. Similar microbial trace fossils may exist in the geological record. If life ever arose on early Mars, similar processes may have occurred there and left recognizable traces.
Ulysses Dust Measurements Near Jupiter
Authors: Grün Eberhard , Zook Herbert A. , Baguhl Michael , Fechtig Hugo , Hanner Martha S. , Kissel Jochen , Lindblad Bertil A. , Linkert Dietmar , Linkert Gudrun , Mann Ingrid B. , McDonnell J. Anthony M. , Morfill Gregor E. , Polanskey Carol , Riemann Reiner , Schwehm Gerhard , Siddique Nadeem
Published: October 2006

Submicrometer- to micrometer-sized particles were recorded by the Ulysses dust detector within 40 days of the Jupiter flyby. Nine impacts were recorded within 50 Jupiter radii with most of them recorded after closest approach. Three of these impacts are consistent with particles on prograde orbits around Jupiter and the rest are believed to have resulted from gravitationally focused interplanetary dust. From the ratio of the impact rate before the Jupiter flyby to the impact rate after the Jupiter flyby it is concluded that interplanetary dust particles at the distance of Jupiter move on mostly retrograde orbits. On 10 March 1992, Ulysses passed through an intense dust stream. The dust detector recorded 126 impacts within 26 hours. The stream particles were moving on highly inclined and apparently hyperbolic orbits with perihelion distances of >5 astronomical units. Interplanetary dust is lost rather quickly from the solar system through collisions and other mechanisms and must be almost continuously replenished to maintain observed abundances. Dust flux measurements, therefore, give evidence of the recent rates of production from sources such as comets, asteroids, and moons, as well as the possible presence of interstellar grains.
Natural Abundances of Carbon Isotopes in Acetate from a Coastal Marine Sediment
Authors: Blair Neal E. , Martens Christopher S. , Des Marais David J.
Published: October 2006

Measurements of the natural abundances of carbon isotopes were made in acetate samples isolated from the anoxic marine sediment of Cape Lookout Bight, North Carolina. The typical value of the total acetate carbon isotope ratio (δ
13
C) was -16.1 ± 0.2 per mil. The methyl and carboxyl groups were determined to be -26.4 ± 0.3 and -6.0 ± 0.3 per mil, respectively, for one sample. The isotopic composition of the acetate is thought to have resulted from isotopic discriminations that occurred during the cycling of that molecule. Measurements of this type, which have not been made previously in the natural environment, may provide information about the dominant microbial pathways in anoxic sediments as well as the processes that influence the carbon isotopic composition of biogenic methane from many sources.
Drosophila
Hybrids in Nature: Proof of Gene Exchange Between Sympatric Species
Authors: Carson H. L. , Nair P. S. , Sene F. M.
Published: October 2006

Genetic studies of two closely related endemic Hawaiian species show that in one area of sympatry about 2 percent of the naturally occurring individuals are hybrids. More than 20 times this many would be expected if the population consisted of a single panmictic unit. Despite hybridization, natural selection appears to maintain the essential integrity of each separate gene pool.
Immunological Tolerance: Transmission from Mother to Offspring
Authors: Auerbach Robert , Clark Susan
Published: October 2006

Mice born and raised by mothers made specifically unresponsive to heterologous erythrocytes by prior treatment with soluble extracts of these cells become themselves tolerant. Tolerance is achieved through nursing since normal neonates fostered by tolerant animals become tolerant, while animals born to tolerant mothers but nursed by normal mice are fully responsive.
Science, Technology, and the Limits of Judicial Competence
Authors: Jasanoff Sheila , Nelkin Dorothy
Published: October 2006

Resolution of technological controversies occupies an increasingly important position in the judicial arena. It is widely believed that traditional processes of adjudication are no longer capable of handling many of the disputes engendered by a complex technological society. This article examines recent litigation based on disputes over science and technology, the burdens on the adjudicatory process, and some proposed reforms. It is argued that such proposals frequently misconceive the problems faced by the courts because they concentrate on the question of technical uncertainty rather than the conceptual and policy issues at stake.
Guidelines for Industry-Sponsored Research at Universities
Authors: Varrin Robert D. , Kukich Diane S.
Published: October 2006

As the number of cooperative research programs between universities and industries grows, the potential for problems that stem from the inherent differences between the two types of organizations increases as well. The key to success in such relationships lies in anticipating problems and developing guidelines for averting them or dealing effectively with them. Ten guidelines for successful university ties with industry are discussed. The topics covered include publication rights, patent ownership, copyrights, confidentiality agreements, research units, faculty consultants, faculty entrepreneurs, international agreements, the sharing of personnel and equipment, and model research agreements.
Food Preference and Length of Life
Authors: Ross M. H. , Bras G.
Published: October 2006

When random-bred rats were given freedom of dietary choice throughout postweaning life, their life-span correlated with the dietary practices before midlife, particularly those exhibited during early life.
Vibrational states of the biopolymer polyglycine II: theory and experiment
Authors: Fanconi Bruno , Finegold Leonard
Published: October 2006

The density of vibrational states, and hence the heat capacity, has been calculated for the parallel-chain hexagonal lattice of 3
1
helical polyglycine. The agreement with experimental results in the temperature range from 1 to 20 K, including an anomaly near 8 K, is the best obtained thus far for homopolypeptides.
Leukemia Virus-Induced Immunosuppression: Scanning Electron Microscopy of Infected Spleen Cells
Authors: Farber Paul , Specter Steven , Friedman Herman
Published: October 2006

Spleen cells from mice infected with Friend leukemia virus were examined by scanning electron microscopy. Whereas splenocytes from normal noninfected animals showed the expected morphologic classes of lymphocytes, including those with smooth surfaces and with numerous villous projections, an alteration of cell type was evident within a few days after infection. Friend leukemia virus caused a rapid decrease in the number of villous cells, with a concomitant increase in the number of cells with smoother surfaces. By the end of the first 1 to 2 weeks after infection the majority of cells were smooth, many showing distinct morphologic changes, including "holes" and a spongy appearance. Nearly all of the splenocytes were abnormal in appearance by days 17 to 30 after infection, with most showing a spongy topography. These changes paralleled the marked immunosuppression induced by Friend leukemia virus infection, as well as the appearance of virus-associated surface antigen on individual splenocytes. Topographic changes evident by examination with scanning electron microscopy were not readily apparent by either standard histology or transmission electron microscopy.
Focal Attention in the Frog: Behavioral and Physiological Correlates
Authors: Ingle David
Published: October 2006

The prey-catching response of frogs toward small moving objects can be facilitated by small movements of the same stimulus a few seconds earlier, even though initial movements seldom trigger the feeding response. This focal attention phenomenon may be related to the observation that one class of tectal unit continues to discharge for a few seconds following a brief stimulus motion. Together with anatomical data of other investigators, results of the present study suggest that self-exciting neural loops within the tectum mediate this type of selective attention.