Search PubMed⌕ Search

Biomedical subjects

M Lyon

Publications and source records attributed to M Lyon.

At least 91 records · Page 5Linked to original sources
PubMed1982

Behavioral alterations during prolonged low level continuous amphetamine administration in a monkey family group (Cercopithecus aethiops).

The continuous presence of endogenous psychotomimetic compounds has frequently been hypothesized in human psychopathology. In related drug-based animal models it would be necessary to demonstrate accumulating behavioral abnormalities despite a low constant drug-level. Using subcutaneously implanted slow-release capsules containing a d-amphetamine base, we studied behavioral effects during 11-weeks of low level but continuous release of this psychotomimetic drug in a socially housed family group of monkeys (drugged father and mother with undrugged infant). Following implantation, locomotion was only slightly affected throughout the drug period. Among visual behaviors, staring gradually increased and, after 5-7 weeks, peaked at a level ten-fold higher than pre-implant levels. Except for infant/female contact, social behaviors were decreased throughout the drug period. Sleep during nights declined by about one-third for the first 8 weeks. In vitro measurements of this capsule type confirmed amphetamine release at 1st-week levels for ca. 8 weeks. Low level prolonged amphetamine intoxication apparently can lead to increasing behavioral abnormalities despite relatively stable drug-release levels.

Amphetamine↗
PubMed1981

A rapid purification of bovine testicular hyaluronidase by chromatography on dermatan sulphate-substituted 1,6-diaminohexane--sepharose 4B.

The binding of bovine testicular hyaluronidase to AH-Sepharose (1,6-diaminohexane--Sepharose) gels substituted with (1) dermatan sulphate, (2) desulphated dermatan sulphate, (3) heparin and (4) de-N/O-sulphated, re-N-acetylated heparin was investigated. Hyaluronidase was found to bind to (1) and (3), but not (2) and (4). On the basis of these observations a preparative scheme for the purification of testicular hyaluronidase was developed. This consisted of two steps: (i) chromatography on dermatan sulphate-substituted AH-Sepharose 4B; (ii) chromatography on acetylated AH-Sepharose 4B. This procedure gave hyaluronidase with a specific activity of 19.1 units (mumol/min)/mg in high yield. Polyacrylamide-gel electrophoresis at pH 4.3 revealed two components, both possessing hyaluronidase activity. Sodium dodecyl sulphate polyacrylamide-gel electrophoresis likewise revealed two close bands with approximate molecular weights of 61000 and 67200.

Animals↗
PubMed1979

Benzodiazepine receptors in the brain as affected by different experimental stresses: the changes are small and not undirectional.

Rats and mice were exposed to several different stress situations to investigate whether brain benzodiazepine receptors were sensitive to altered external or internal environmental circumstances. All stresses were applied for several days. Electrical foot shock and post-natal isolation of newborn pups resulted in small (7--25%; P less than 0.05--0.001) decreases in benzodiazepine receptor binding in some cerebral cortex or hippocampal areas while immobilization stress resulted in a small (9%; P less than 0.05) increase in frontal cortex. Other brain areas (i.e., striatum, cerebellum, pons-medulla, and occipital cortex) and other stress forms (isolation of male mice, forced swimming in cold water, or chronic amphetamine intoxication) did not change receptor binding. The effect of prolonged stress on benzodiazepine receptors is complex and not very pronounced.

Aggression↗
PubMed1978

Evidence for cell loss in corpus striatum after long-term treatment with a neuroleptic drug (flupenithixol) in rats.

The number of nerve cells in two different areas of the corpus striatum (i.e., ventrolateral and dorsomedial) was estimated in rat brain after long-term (36 weeks) treatment with the neuroleptic flupenthixol. Nine rats were given weekly injections of 4 mg/kg flupenthixol dissolved in Viscoleo i.m., and seven rats received Viscoleo alone. Fourteen to 18 weeks after the last drug injection, the animals were decapitated and half of each brain was fixated with formalin for cell-count analysis and the remaining half used for a biochemical analysis (Nielsen, 1977). Separate cell counts in the ventrolateral and dorsomedial corpus striatum yielded a significant cell loss of approximately 10%, but only in the ventrolateral striatum of treated animals. These results suggest at least one concrete anatomical basis for the behavioral and biochemical deficits found in the same animals, as reported earlier. The results further suggest that persistent irreversible anatomical changes can follow long-term neuroleptic treatment. The inconsistencies of results regarding cell loss in the corpus striatum may be due to neglect of dorsal-ventral structural differences in corpus striatum.

Animals↗
PubMed1978

Interactions of Shope papilloma virus with some other DNA viruses.

The interactions of Shope papilloma virus (SPV) with primate and rabbit cells in tissue culture have been investigated. The rabbit cell cultures were derived from normal epidermis, from SPV-infected epidermis, from SPV-induced papillomas, and from an SPV-associated carcinoma. None of these cell cultures, whether infected in vitro with SPV or derived from tissues infected in vivo, ever produced infectious SPV or even detectable viral antigens. Some other DNA viruses behaved differently in cells which had been in previous contact with SPV either in vitro or in vivo. Adenovirus type 5 multiplies better in human cells infected 24 h previously with SPV than in the untreated controls. The production of infectious virions of either herpes simplex virus or Shope fibroma virus is reduced in cells derived from SPV-induced papillomas or carcinoma, due, apparently, to a defect in viral maturation. Of the rabbit cells, only those derived from in vivo infected tissue, or those previously infected in vitro with SPV, could be transformed by SV40. The rabbit cell lines derived from papillomas or carcinoma differed from their counterparts derived either from normal epidermis or from tissue infected 24 hrs before biopsy, in their karyotype, and in their ability to grow in soft agar. Similar karyotypic alterations were induced in cells derived from healthy epidermis by infection in vitro with SPV.

Adenoviruses, Human↗
PubMed1976

[Effects of colchicine, vinblastine and mercury p-hydroxybenzoate on the multiplication of adenovirus 5 in HeLa cells].

After 30 min incubation at 37 with 10(-4) M PHMB (p-hydroxymercuribenzoate), monolayers of HeLa cells are not affected; after 3 h exposure to 10(-5) M colchicin or 2.5 X 10(-5) M vinblastine, HeLa cells are not altered morphologically but the number of cells is decreasing between 1 and 2 days post treatment. When cells are kept in suspension after trypsinization, their ability to adhere to the Petri dishes is not altered with 10(-4) M PHMB but only 50% of the cells are able to attach after treatment with colchicine or vinblastine. Adenovirus type 5 is unsensitive to the effect of colchicine and vinblastine at various concentrations, after 3 h incubation at 37. With 10(-3) M PHMB, the virus is inactivated, infectivity and hemagglutinating activity are almost abolished but the particles are unsensitive to pancreatic DNase, so that the structure of the viral particle is intact. This effect is reduced with 10(-4) M PHMB. The adenovirus 5 multiplication is not affected when HeLa cells are treated with 10(-5) M colchicine or 2.5 X 10(-5) M vinblastine, before and during adsorption of the virus. The viral production decreases after 24 h treatment with colchicine or vinblastine. Treatment with 10(-4) M PHMB does not influence intra- or extracellular viral yield.

Adenoviridae↗
PubMed1975

[Immunofluorescence study of the migration of adenovirus 5 in HeLa cell cytoplasm during the penetration phase].

Using the indirect immunofluorescence technique in presence of anti-adenovirus-5 antibody, fluorescent spots were observed two hours after adsorption at 4 degrees C onto HeLa cells on the surface of the cells. The spots subsequently became intracytoplasmic and persisted about 7 to 8 h. Intense fluorescence was further observed in the whole cytoplasm and in the nucleus 12 h following the injection.

Adenoviridae↗
PubMed1975

A prospective evaluation of the lecithin/sphingomyelin ratio and the rapid surfactant test in relation to fetal pulmonary maturity.

Fetal lung maturity was correlated to the results of amniatic fluid analysis in 578 samples obtained over a 2 1/2 year interval. Lecithin/sphingomyelin (L/S) ratios obtained by planimetric and densitometric methods were compared to the rapid surfactant test (RST). Both the planimetric L/S ratio (P L/S) and the densitometric L/S ratio (D L/S) correlated positively in a highly significant fashion with the RST. Both RST and D L/S were reliable in predicting fetal lung maturity (99 to 100 per cent, respectively). The RST was the most reliable test for fetal lung immaturity (69 per cent). Therefore, this series indicates that the RST could be used as a primary method with the D L/S being useful as an additional indicator of fetal maturity when the RST was intermediate, or the sample contaminated with blood and/or meconium.

Amniotic Fluid↗