Search PubMed⌕ Search

Biomedical subjects

M Globus

Publications and source records attributed to M Globus.

At least 55 records · Page 3Linked to original sources
PubMed1983

Chronic L-dopa administration decreases striatal accumulation of dopamine from exogenous L-dopa in rats with intact nigrostriatal projections.

To examine whether chronic administration of L-dopa can affect its own utilization in striatum, rats were injected once daily for 30 days with L-dopa and carbidopa or with saline. On day 31, saline and L-dopa animals were sacrificed 1, 2, or 3 hours after L-dopa injection. In rats given long-term L-dopa, the elevations in striatal dopamine concentrations induced by L-dopa administration were smaller and of shorter duration than those in controls. Such changes did not occur in animals pretreated with L-dopa for only 10 days. Results suggest that prolonged L-dopa therapy may decrease striatal accumulation of dopamine from exogenous L-dopa even when the nigrostriatal projections are intact. Therefore, it is possible that declining efficacy of L-dopa in parkinsonism may be due to effects of the drug itself and not only to disease progression.

Animals↗
PubMed1982

Studies of mitosis in excised limb regenerates of the newt, Notophthalmus viridescens.

Subsequent to excision and explantation of the limb blastema into culture medium, there is an abrupt reduction in mitotic index lasting several hours. Coincident with the disappearance of mitosis, abnormal mitotic figures (AMFs), lacking the condensed chromosomal nature of normal figures, are seen. These persist until normal levels of mitotic activity are restored approximately 6 hr later. The transient loss of mitotic activity is observed in both ganglionated and nonganglionated explants. The large number of prophase figures observed at time zero were sharply reduced within minutes, without concomitant increases in the later phases. The possibility that some cells, without completing mitosis, become temporarily indistinguishable as mitotic figures, is discussed in terms of chromosomal decondensation and recondensation.

Animals↗
PubMed1982

The effect of chronic bromocriptine and L-dopa on spiperone binding and apomorphine-induced stereotypy.

Chronic treatment with dopamine (DA) agonists has been reported in various paradigms to cause supersensitivity of DA receptors or, contradictorily, subsensitivity of DA receptors. The present study administered 15 mg/kg bromocriptine for 7 days and measured both striatal spiperone binding and apomorphine (AP)-induced stereotypy. A significant decrease in AP-induced stereotypies was observed after chronic bromocriptine treatment, but without a significant parallel decrease in striatal spiperone binding. These results probably do not represent a true agonist-induced subsensitivity, but possibly show that residual bromocriptine in vivo may antagonize AP-induced stereotypy. Since some reports have suggested that L-Dopa may specifically reverse the increases in DA receptor number induced by chronic haloperidol, we also studied the effect of 7 days of L-Dopa treatment after 6-week chronic haloperidol treatment of mice. While chronic haloperidol significantly increased striatal spiperone binding, subsequent L-Dopa treatment did not reverse this biochemical supersensitivity. It is concluded that agonist induction of subsensitivity in the DA system is difficult to reproduce and may depend on highly specific dosage conditions and treatment schedules.

Animals↗
PubMed1982

Ictal hemiparesis.

2 cases of ictal hemiparesis in adults are presented. The clinical picture was recurrent transient hemiparesis with contralateral focal hemispheric discharge. The etiology in such cases seems to be a stimulation of the second somatosensory and/or the supplementary motor areas. Emphasis is placed on the fact that, while transient ischemic attacks in adults are readily diagnosed, some cases might be subject to misdiagnosis, being actually due to inhibitory fits.

Aged↗
PubMed1981

Promotion of mitosis in cultured newt limb regenerates by a diffusible nerve factor.

Regeneration blastemata of adult newt forelimbs were cultured transfilter to dorsal root ganglia on extremely low porosity (0.05 mu m) filters. Mitotic index profiles in these blastemata were compared with those obtained using filters of greater porosity (0.45 mu m). In the above experiments nerves and blastema tissue were separated by 5 or 25 mu m, i.e., the thickness of the respective filters. The results show that the transfilter mitogenic effect of the nerves was retained when the lower pore size filters were used. In addition, sensory ganglia grown at the bottom of a culture well, separated from the blastema explants by a distance of approximately 2 mm, were nevertheless able to promote blastema cell proliferation. The ganglia can thus be considered to be providing a "sustained conditioning" of the medium with neuromitogenic factor(s). This study also shows that nerves can promote blastema cell mitosis, although cell-to-cell contact between nerves and responding cells was precluded.

Animals↗
PubMed1978

Effect of maternally administered sodium nitrite on hepatic erythropoiesis in fetal CD-1 mice.

A commonly used food preservative, sodium nitrite, was administered to pregnant CD-1 mice at a concentration of 0.5 mg/mouse/day. Embryotoxic and teratogenic effects on the hemopoietic tissues and skeletons of their offspring, were evaluated. Fetal mortality, resorptions, the mean number of offspring per litter, the mean weight per embryo and the incidence of skeletal malformations, were not significantly different from controls. Hemopoietic cell suspensions, prepared from the livers of treated and control 14-, 16- and 18-day embryos, were cytocentrifuged onto microscope slides and differential counts were performed after staining with benzidine and Wright-Giemsa stain. The results indicate that maternally administered Na nitrite, stimulates fetal hepatic erythropoiesis. This was manifested in a statistically significant increase in the percentage of polychromatophilic erythroblasts and mature erythrocytes at 14 and 16 days of gestation, respectively. The possibility that Na nitrite may induce fetal methemoglobinemia is discussed and mechanisms responsible for the observed erythroid stimulation, are considered.

Animals↗
PubMed1977

Hormone control in regeneration: effects of somatostatin on appendage regeneration, blood glucose and liver glycogen in Diemictylus viridescens.

In the present communication, synthetic somatostatin, a hypothalamic factor which has a known inhibitory effect on the release of growth hormone, thyroid-stimulating hormone, prolactin, insulin and glucagon in man and other mammals, was found to have an inhibitory effect on limb and tail regeneration in adult Diemictylus viridescens, when the newts were treated with a daily dose of 3-5 or 15 microgram/animal for a period of 34 days post-amputation. At the higher dose, the animals exhibited total inhibition of appendage regeneration in a few cases and the remainder showed a considerable delay compared to the controls; none of the experimental animals reached the advanced four-digit stage achieved by the controls. Furthermore, the blood glucose and liver glycogen values in the somatostatin-treated animals were significantly lower than the control values. Mechanisms in the storage, mobilization and utilization of glucose (involving hormones) are discussed in relation to appendage regeneration in the newt and possible controls of regeneration at the level of the hypothalamus are suggested.

Animals↗
PubMed1976

An in vitro analogue of early chick limb bud outgrowth.

Our culture system appears to represent an in vitro analogue of early chick limb morphogenesis. Organized mesodermal cell accumulations resembling limb buds were derived from a monolayer of limb mesoderm cells when covered by limb ectoderm which included the apical ectodermal ridge (AER). The ridge retained its normal configuration when grown over a limb mesoderm monolayer and the mesoderm cells accumulated under the ridge to form a multilayered structure (10-25 cells in thickness) with the characteristic shape of a limb bud. Ectoderm which did not include the ridge failed to promote the formation of limb-like mesodermal accumulations thus the action of the ridge appears to be specific. The AER-elicited expression of mesodermal cell behaviour leading to early limb outgrowth is discussed in terms of possible morphogenetic mechanisms involved i.e. differential mitosis, cell migration, changes in cell shape and especially the adhesive properties of the cells.

Cell Division↗