Glutamate decarboxylase activity in brain regions of differentially-housed mice; a difference in the olfactory bulb

Summary Glutamate decarboxylase (GAD) activities were determined in homogenates of 8 brain regions of mice that had been differentially housed (isolated vs grouped) for 4–9 weeks. GAD activity was lower in whole forebrains and in olfactory bulbs of isolated mice, changes which might be associated with their increased aggressiveness.     

Die Wirkung von Eiweissfraktionen normaler menschlicher Sera auf die Thrombocytenzahl der Maus

Summary We investigated the thrombocytosis-producing activity of different protein-fractions of human sera in mice. The whole sera, the albumin,- and-globulins were ineffective, whereas the-globulins caused a more or less exact thrombocytosis in mice. The effectiveness of the thrombopoetic activity present in normal human sera is probably inhibited by a factor connected with another protein-fraction.     

Neuronal nicotinic receptors: insights gained from gene knockout an knocking mutant mice

Neuronal nicotinic acetylcholine receptors are ligand-gated ion channels that subserve a range of functions in the brain and peripheral nervous system. They are pentamers variously composed of (₂– ₁₀) and subunits ( ₂– ₄). Pharmacological and ligand-binding studies have shown that the different subunits vary in their distribution and channel properties, but precise delineation of the in vivo function of individual subunits has been hampered by lack of subunit-specific antagonists. The development of transgenic mice with targeted deletions of specific subunits (knockout mice) or mutations in critical receptor domains (knockin mice) has extended understanding of nicotinic receptors, revealing that some subunits are necessary for viability, whereas others mediate modulatory effects on learning and memory, locomotion, anxiety, nociception, dopaminergic neurotransmission, seizure threshold, development of the visual system and autonomic function. In some cases, studies of transgenic mice have confirmed expectations derived from pharmacological and expression studies, but in other cases, compensation by related subunits has revealed a degree of functional redundancy not predicted by previous approaches.Received 19 September 2002; received after revision 12 November 2002; accepted 11 December 2002     

Refeeding of mice after fasting stimulates cell renewal in the gall bladder epithelium

Summary The effect of refeeding of mice after a fasting period on the uptake of 3H-thymidine and on mitotic activity in the gall bladder epithelium was studied by histoautoradiography. A significant increase in both DNA synthesis and mitotic activity was observed after 12 h of refeeding.Acknowledgments. This work was supported by the Fonds voor Geneeskundig Wetenschappelijk Onderzoek and by the Algemeene Spar-en Lijfrentekas.     

Glucan-induced enhancement of hemopoietic recovery in gamma-irradiated mice

Summary A single pre- or postirradiation application of -(13)-D-glucan, a potent reticuloendothelial stimulant, enhances hemopoietic recovery in sublethally gamma-irradiated mice. Pretreatment of mice with glucan significantly reduces lethal radiation effects.     

Inhibition of tumor promotion by a lecanoric acid analogue

Summary 3, 5-Dichloro-2,4-dihydroxybenzanilide, an inhibitor of histidine decarboxylase, inhibited skin tumor promotion induced by 12-O-tetradecanoylphorbol-13-acetate in mice.Acknowledgments. The authors wish to thank Miss H. Iwami for technical assistance and members of the Central Research Laboratory of Sanraku-Ocean Co., Ltd for supplying lecanoric acid analogues. This work was supported in part by the Grantsin-Aid for Cancer Research from the Ministry of Education, Science and Culture and the Ministry of Health and Welfare of Japan.     

Changes in mouse liver superoxide dismutase activity and lipid peroxidation during embryonic and postpartum development

Summary In inbred mice possessing high and low tissue superoxide dismutase (SOD) activity, it was observed that the difference in the SOD activities of the liver homogenates during development attains the maximum characteristic of the strain by about the 150th day. Subsequently, the SOD activity change displays a tendency in contrast with the age and the basic state. In the course of the development, a difference was also observed between the 2 mouse strains in the lipid peroxidation variation.Part XVIII of the series Properties of enzymes.     

Insulin secretion and (pro)insulin biosynthesis of cultured mice islets after glibenclamide loading in vitro

Summary Isolated islets from C57B1/6J mice exposed to 10 mmoles/1 glucose supplemented with 5 g/ml glibenclamide for 48 h released significantly less insulin in the subsequent short-time incubation thanuntreated controls (without glibenclamide), whereas insulin biosynthesis was not suppressed by glibenclamide treatment.Investigations were carried out as a part of the ForschungsprojektDiabetes mellitus und Fettstoffwechselstörungen, supported by the Ministry of Health of the GDR.     

Ultrastructural localization of catalase and D-amino acid oxidase in ‘normal’ fetal mouse liver

Summary In the hepatocytes of normal fetal mice from mothers which were carriers of muscular dysgenesis, catalase and D-amino acid oxidase (DAAO) positive as well as negative peroxisomes were observed. DAAO reaction product was occasionally localized in patches around cell membranes and DAAO-positive peroxisomes were frequently observed near mitochondria.     

Ethanol diminishes the toxicity of the mushroomAmanita phalloides

Summary Survival of mice after lethal doses of a lyophilizate fromAmanita phalloides (death cap) was markedly increased by single doses of ethanol applied 30 min before or 5 min after the mushroom. Hepatic histopathological damage (confluent necrosis) was largley prevented. Acute, but not chronic, consumption of ethanol may thus influence favorably the outcome of death cap poisoning and should be taken into consideration in the evaluation of therapeutic measures.     

Adenosine-5′-triphosphate levels in experimental CaNT and Fib/t tumours of varying volume and degree of hypoxia

Summary The variation of adenosine-5-triphosphate (ATP) content per unit mass of tumour, versus tumour volume was measured in vivo under normoxic conditions, using CaNT and Fib/t murine tumours grown in CBA and WHT mice respectively. A monotonically decreasing relation was found. Artificially induced tumour hypoxia resulting from 15 min of clamping was accompanied by reduced ATP levels.     

Serum proteins of mice with splenomegaly

Summary Our earlier serum electrophoretic study in lethargic mutant mice showed that the quantity of protein in 1 band is inversely related to the size of the spleen. In this study, we demonstrate that this protein band almost entirely disappears in mice with splenomegaly following spontaneous skin infection. The results suggest that this serum protein may play a role in regulating growth of lymphoid tissue.This study is made possible through support of Medical Research Service of the US Veterans Administration. We thank Dr Thomas B. Pool, Department of Anatomy, The University of Texas Health Science Center, for editorial assistance.     

Methyl cellosolve-induced sensitization of mice to bacterial endotoxin

Summary Treatment of mice with a sublethal dose of methyl cellosolve renders the animals 64-fold more sensitive to the toxic effects of bacterial endotoxin.Acknowledgments. I would like to thank Mr Larry Davis for his excellent technical assistance in these studies.This work was supported by the Naval Medical Research and Development Command, Research Work Unit No. MF585240013.1026. The opinions and assertions contained herein are the private ones of the writer and are not to be construed as official or reflecting the views of the Navy Department or the naval service at large. The experiments conducted herein were conducted according to the principles set forth in the Guide for the Care and Use of Laboratory Animals, Institute of Laboratory Resources, National Research Council.     

Muscular dystrophy in adult mice chronically treated with Δ9- THC at behavioural doses

Summary After chronic treatment with ₉-THC at behavioural doses, a muscular dystrophy was demonstrated in adult mice, on the basis of histological and biochemical data and of functional tests on muscle.Grant of the Italian Ministry of Health, Service of Social Medicine, and of C. N. R.     

Anti-phalloidine and anti-α-amanitine action of silybin in comparison with compounds similar to structural parts of silybin

Summary Silybin significantly antagonises the lethal poisoning of mice with -amanitine or phalloidine. In the same test, taxifolin, coniferyl alcohol, fisetin and (+)-catechin were not effective.     

Metabolism of 3β-hydroxycholest-5-en-26-oic acid in hamsters

Summary Metabolism of 26-hydroxycholesterol to 3-hydroxychol-5-en-24-oic acid and other C24-bile acids has been expected to occur by way of 3-hydroxycholest-5-en-26-oic acid in studies in vitro. 3-Hydroxycholest-5-en-26-oic acid was infused intravenously into bile fistula hamsters and the following C24-bile acids were identified: 3-hydroxychol-5-en-24-oic acid, lithocholic acid, chenodeoxycholic acid, and a small amount of cholic acid.     

Uptake of D-glucose anomers by rat retina

Summary Uptake ofd-glucose anomers by isolated rat retina was studied. After 3 min incubation at 37°C in the presence of or anomer (750 g/ml), a significantly greater uptake (1.32 mg/g wet tissue) of -anomer was observed compared with that of -d-glucose (1.11 mg/g wet tissue). This result and other data suggest that the carrier ford-glucose transport in the retina prefers the -anomer stereospecifically.Acknowledgment. The authors are grateful to Mr S. Suzuki for his technical assistance.     

Protein kinase C regulation of GABAA receptors

Pharmacological studies with drugs that activate or inhibit several protein kinase C (PKC) isozymes have identified the PKC family of serine-threonine kinases as important in the regulation of -aminobutyric acid type A (GABA_A) receptor function. PKC modulates GABA_A receptor surface density, chloride conductance and receptor sensitivity to positive allosteric modulators such as neurosteroids, ethanol, benzodiazepines and barbiturates. Recent studies using PKC isozyme-selective reagents and gene-targeted mice have begun to identify critical roles for three isozymes, PKCII, PKC and PKC, in various aspects of GABA_A receptor regulation. Progress in this field touches upon therapeutic areas that are of great clinical importance such as anxiety and addiction. Increased understanding of how PKC regulates GABA_A receptors and which PKC isozymes are involved holds promise for development of new treatments for diverse neuropsychiatric disorders.Received 2 August 2004; received after revision 17 August 2004; accepted 21 August 2004     

Evidence for the extranuclear localization of thymosins in thymus

A new radioimmunoassay has been developed for thymosin ₄ by generating rabbit polyclonal antibodies against the synthetic N-terminal peptide fragment 1–15 coupled to KLH. The synthetic analogue [Tyr¹²]-thymosin ₄ (1–15) was used as tracer. This radioimmunoassay, with a useful range of 10–1000 pmoles, showed cross-reactivity with the second homologous -thymosin of man and rat (thymosin ₁₀) but not of calf (thymosin ₉). This radioimmunoassay, together with an improved radioimmunoassay for the N-terminus of parathymosin , was employed for the measurement of the levels of thymosin ₄ and parathymosin in nuclear and extranuclear extracts of calf thymus. The bulk of these polypeptides was found in the extranuclear material whereas only traces were observed in the nuclear environment, which indicates the extranuclear localisation of - and -thymosins.     

Narcotic antagonism of seizures induced by a dopamine-derived tetrahydroisoquinoline alkaloid

Summary This paper describes experiments designed to evaluate whether the narcotic antagonist naloxone significantly interferes with seizures induced by tetrahydroisoquinolines (TIQs). In these experiments we found that naloxone significantly reduced seizure scores induced by intra-cranially infusing mice with 50 g of the dopamine-derived tetrahydroisoquinoline (TIQ) alkaloid, 6,7-dihydroxy TIQ. These findings support an opioid involvement in the actions of TIQs and may lead to further understanding of opioid-mediated novel excitatory receptors.