Search PubMed⌕ Search

Biomedical subjects

G Mitchell

Publications and source records attributed to G Mitchell.

At least 217 records · Page 12Linked to original sources
PubMed1976

Effects of sleep of restricted sleep. A cat case study.

One male cat was adapted to different schedules of restricted sleep. The cat was allowed to go to sleep during a certain number of hours per day. During the rest of the 24 h period, wakefulness was enforced by means of a treadmill. The following schedules of restricted sleep were run: 12 h sleep--12 h treadmill (12S--12T), 8S--16T, 4S--20T. The cat was also adapted to a 36 h day: 12S--24T. The sleep was investigated after at least 2 weeks on each schedule and compared to ad lib. sleep (24S--0T). As available sleep time bacame shorter, the composition of the sleep changed. LSWS (in % of available sleep time) decreased, while DSWS % and REM sleep % increased. The length of the DSWS and REM sleep episodes increased with decreasing sleep time, as did sleep cycle length.

Animals↗
PubMed1976

Evidence for a dual innervation affecting local blood flow in the hypothalamus of the conscious rabbit.

We have attempted to evaluate the role of adrenergic nerves which arise from the superior cervical ganglia or which are intracerebral throughout their course, in the control of local cerebral blood flow (CBF). Hypothalamic blood flow (HBF) was measured in the conscious rabbit by the 133Xe-clearance technique. Stimulation of the upper brainstem, using 5-Hz, 3-V, 1-msec, square wave pulses, increased by HBF by a mean of 7.6 ml/100 g per min (P less than 0.005). This effect was abolished by the intrahypothalamic injection of the beta-adrenoreceptor blocker, propranolol, and by chemical sympathectomy of the hypothalamus or of the upper brainstem with 6-hydroxydopamine, but was not altered by bilateral cervical ganglionectomy. Intrahypothalamic injection of 0.1 mug of tyramine caused a mean decrease in HBF of 15.6 ml/100 g per min (P less than 0.001). This effect of intrahypothalamic injection of tyramine was abolished by bilateral cervical sympathectomy but not by chemical sympathectomy of the upper brainstem. These results support the idea that local CBF, at least in the hypothalamus, is mediated by two distinct pathways. The first consists of the sympathetic nerves which arise in the cervical ganglia, and which activate intrahypothalamic alpha-receptors to cause constriction. The second is an entirely intracerebral noradrenergic pathway which stimulates beta-receptors to cause vasodilation.

Animals↗
PubMed1975

Physiological and DNA characterization of Candida maltosa, a hydrocarbon-utilizing yeast.

Selected yeast classified as Candida sake van Uden et Buckley were examined for their physiological, morphological and immunological properties and their DNA relatedness. Candida maltosa Komagata, Nakase et Katsuya is herein recognized as a species separate from C. sake, Candida maltosa was distinguished from C. sake and from C. tropicalis by insignificant DNA reassociation. In addition, C. maltosa was distinguished from C. sake by its higher maximal growth temperature and lower guanine plus cytosine content of its DNA and from C. tropicalis by its failure to utilize soluble starch for growth and its resistance to cycloheximide. The species C. cloacae and C. subtropicalis are placed in synonymy with C. maltosa.

Alkanes↗
PubMed1975

Initial heterosexual behavior of adolescent Rhesus monkeys (Macaca mulatta).

This report described the first heterosexual encounters of twelve 3-year-old rhesus monkeys, six of each sex. The subjects were all laboratory-born and were reared in wire cages for the first 8 months of life, accompanied only by their mothers. After these animals were weaned, each was placed in a cage with another animal of the same age and sex. The pairs formed in this way remained intact until the animals were 2 years old. When heterosexual dyads were formed, some of the subjects attached and bit the animal with which they had been paired, while the members of other pairs established almost immediate rapport as evidenced by mutual grooming and adequate sexual behavior. The initial sexual interactions of most pairs were uncoordinated, but all eventually demonstrated qualitatively species-typical patterns of sexual behavior. Despite their immaturity, two of these pairs succeeded in producing offspring, both of which were healthy.

Aggression↗
PubMed1975

Blood-lead levels of monkeys treated with a lead-containing (N2) root canal cement: a preliminary report.

The effect of a root canal filling material on the level of lead in blood of rhesus monkeys was examined by anodic stripping voltometry. Blood-lead levels after root canal treatment with N2 cement were elevated when compared to preoperative controls. Lead 210 was incorporated into the leadfree N2 cement to identify the source of lead. Analyses of blood samples for 210Pb indicated that the lead originated from the filling material.

Animals↗
PubMed1975

The lead content of teeth. Evidence establishing new minimal levels of exposure in a living preindustrialized human population.

Teeth were collected from populations differing in their degree of industrialization and from prehistoric populations. Lead analysis of dentine revealed that in contemporary teeth the lead level was related to the degree of industrialization and that in prehistoric teeth very low concentrations of lead were present. Because tooth lead reflects the body burden of lead, this result suggested that the prehistoric populations and modern nonindustrial populations were exposed to environments low in lead. Teeth from a contemporary population of nonindustrialized Indians of the Lacandon forest in Mexico contain lead in concentrations comparable with those of the prehistoric populations. Comparison of the Indian teeth with teeth from a modern industrial population reveals a 45-fold difference in median tooth lead level. This finding lends support to the hypothesis that high levels of urban lead pollution result in elevated body burdens of lead.

Adult↗
PubMed1975

Procaine in porcine malignant hyperthermia.

Serum creatine phosphokinase, rectal temperature and muscle pH at death were measured in three halothane-susceptible Landrace pigs. Two of the pigs were treated with procaine. Although the course of the syndrome was different in the treated pigs, procaine did not reverse the established malignant hyperthermia syndrome.

Animals↗
PubMed1975

Adrenoceptors in intracerebral resistance vessels.

1. The effects of tyramine and isoprenaline on hypothalamic blood flow (HBF) were measured in conscious rabbits. 2. Injections of small doses of tyramine caused an increase in HBF while larger doses caused a decrease in HBF. 3. Isoprenaline injections also produced an increase in HBF. 4. The vasodilatation induced by isoprenaline and the small dose of tyramine was blocked by propranolol. 5. The vasoconstriction induced by the larger doses of tyramine was abolished by phenoxybenzamine. 6. Chemical sympathectomy of the hypothalamus with 6-hydroxydopamine and depletion of biogenic amines by reserpine also abolished tyramine-induced vasocoonstriction. 7. These results suggest the presence of alpha- and beta-adrenoceptors in cerebral resistance vessels, and that these receptors may be activated by released (endogenous) noradrenaline.

Animals↗
PubMed1975

A fifteen-year review of female admissions to Carstairs State Hospital.

A survey was made of all female admissions to the State Hospital, Carstairs, between the time of the first female admission in 1959, and 31 December 1973. There were 66 female admissions, constituting 7-1 per cent of the total admissions over the same period. The females fall into two separate sub-groups. The first consists of persistently violent patients transferred from other hospitals, suffering from mental subnormality or personality disorder; they have a poorer prognosis than the second group, who are sent from Courts or prison because of single serious acts of violence often directed at a member of the family, and who suffer from a personality disorder or from schizophrenia. Some features of the two groups are compared and contrasted. There may be an increase in the proportion of pateints in the first group being admitted to the State Hospital, and some implications of this trend are discussed.

Adult↗
PubMed1975

A survey of female patients in Carstairs State Hospital.

The characteristics of the female population in Carstairs State Hospital are described. The patients were predominantly young, single and physically fit, with a history of significantly more previous psychiatric admissions than their male counterparts. Thwy showed a greater degree of violence towards both themselves and others before their admission to Carstairs; and their length of stay was much shorter. One third of the patients have an IQ of less than 70.

Adolescent↗
PubMed1975

On the toxicity of procaine for pigs.

Procaine caused respiratory arrest in halothane-anaesthetized normal Landrace pigs at a dose of 4,2 - 8,2 mg/kg. In some cases death due to respiratory failure occurred after giving 10 - 13 mg/kg. Because of its toxicity in pigs procaine is unsuitable for treating the porcine malignant hyperthermia syndrome.

Anesthesia, Inhalation↗
PubMed1975

Factors affecting serum creatine phosphokinase activity in pigs.

Serum creatine phosphokinase activity was determined in German Landrace and Landrace x Large White pigs from 11 weeks to 28 weeks of age. A very pronounced age dependence of enzyme activity was observed in both groups, peak activities occurring at 19 weeks of age for the German Landrace and at 15 weeks for the crosses. The large increase in serum creatine phosphokinase activity observed occurred during the rapid phase of growth after which enzyme levels returned close to initial values. Sedatives and the stress of handling while obtaining blood can also cause raised serum creatine phosphokinase levels and complicate the interpretation of the data in regard to the detection of the stress syndrome. Enzyme activity also displayed a diurnal variation thus introducing a further parameter in the use of creatine phosphokinase activity for detection of the stress syndrome. Certain limitations in the method of measurement of creatine phosphokinase are discussed.

Age Factors↗