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Biomedical subjects

S J Mitchell

Publications and source records attributed to S J Mitchell.

69 records · Page 4Linked to original sources
PubMed1981

Young mentally handicapped adults in three London boroughs: prevalence and degree of disability.

A survey of 282 young adults, mentally handicapped on an administrative definition, was undertaken in th London Boroughs of Hounslow, Hammersmith, and Ealing between October 1978 and April 1980. The prevalence of mental handicap in the age group born between 1958 and 1963 was calculated, and variations were shown between the three boroughs and within the borough of Ealing. The findings suggested that the prevalence of severe mental handicap in this area is not markedly different from rates found in other British studies, but the administrative prevalence is inflated because numbers of mildly handicapped school leavers subsequently use the services for the mentally handicapped. Subjects were classified according to behavioural disabilities: young people in residential care were more likely to be severely incontinent, not literate, and without speech, but overall there was no relationship between degree of disability and placement in residential care.

Adolescent↗
PubMed1980

Generation of theta rhythm in medial entorhinal cortex of freely moving rats.

A regular slow wave theta rhythm can be recorded in the medial entorhinal cortex (MEC) of freely moving rats during voluntary behaviors and paradoxical sleep. Electrode penetrations normal to the cortical layers proceeding from the deeper to the more superficial layers reveal a continuous theta rhythm in layers IV-III (deep MEC theta rhythm) with an amplitude maximum in layer III, a null between the outer one-third of layer III and the inner one-half of layer I, and a continuous phase-reversed theta rhythm in layers II-I (superficial MEC theta rhythm) with an amplitude maximum there. Deep MEC theta rhythm is similar in phase and wave shape to CA1 theta rhythm; superficial MEC theta rhythm is similar in phase to DG theta rhythm. Laminar profiles throughout MEC show that the theta rhythm is generated there; it is not volume conducted from hippocampus.

Animals↗
PubMed1978

Measurement of fasting and postprandial plasma VIP in man.

A specific radioimmunoassay has been developed capable of detecting 1.5 pmol VIP/l plasma with 95% confidence. The antisera employed reacted most avidly with whole VIP, partly with C terminal, but not with N terminal fragments. In 110 healthy fasting volunteers plasma VIP concentrations were estimated to lie between 0.5 and 21 pmol/l (median 1.7). No significant change was seen after ingestion of a standard test meal.

Adolescent↗
PubMed1978

Vasoactive intestinal peptide in man: pharmacokinetics, metabolic and circulatory effects.

Graded doses of 0.6, 1.3, and 3.3 pmol/kg/min of vasoactive intestinal peptide (VIP) were intravenously infused over 30 minute periods in four healthy volunteers and plasma VIP levels were measured by radioimmunoassay. Even with the smallest dose of VIP, plasma concentrations rose markedly above normal values. Infusion of higher VIP doses resulted in mean plateau levels of circulating VIP which were in the range of VIP values found in the Verner-Morrison syndrome. After cessation of the VIP infusions, plasma VIP levels fell strikingly by first order kinetics with an average disappearance half-time of one minute. The apparent metabolic clearance rate was about 9 ml/kg/min and the apparent volume of distribution for VIP was approximately 14 ml/kg. During infusion of the highest VIP dose, previously shown to induce one-fifth maximum pancreatic juice secretion, plasma concentrations of glucose, free fatty acids, and calcium were slightly but significantly raised, the pulse rate and the amplitude of blood pressure were increased, and cutaneous flushing occurred. The spectrum of effects accords well with some abnormalities seen in the Verner-Morrison syndrome. The present data, however, do not support a role for VIP as a circulating hormone, at least under physiological conditions.

Adult↗
PubMed1978

Experimental evidence for vasoactive intestinal peptide as the cause of the watery diarrhea syndrome.

We have infused pure porcine vasoactive intestinal peptide (VIP) into 8 healthy ambulant unsedated pigs. At plasma VIP levels closely comparable to those found in the human Verner-Morrison syndrome, gross watery diarrhea and hypokalemia were produced. When the VIP infusion was discontinued the water diarrhea ceased abruptly. This study therefore provides some evidence to implicate VIP as a possible causal agent in the pathogenesis of the human watery diarrhea syndrome.

Animals↗
PubMed1978

Release of VIP, secretin and motilin after duodenal acidification in man.

Plasma VIP, secretin and motilin were measured in 9 volunteers following intraduodenal instillation of 50 ml of 0.1 mol/1 HCl over 3 minutes. VIP rose from 1.7 +/- 0.7 pmol/1 to a peak at 6 minutes of 6.6 +/- 0.9 pmol/1 and was still significantly elevated at 30 minutes. By comparison the elevation of secretin was more transitory rising from a basal value of 2.5 +/- 0.4 pmol/1 to a peak of 10 +/- 1.5 pmol/1 at 3 minutes and returning to baseline by 10 minutes. The rise of motilin, from a higher baseline, was intermediate in pattern, from 23 +/- 7 pmol/1 basally to a 4 minute peak of 40 +/- 10 pmol/1. Thus the elevation of VIP was the most longlasting, and while probably not of sufficient magnitude to stimulate pancreatic bicarbonate secretion via the circulation, could reflect a significant local role in regulating the response of the intestinal mucosa to acid.

Bicarbonates↗
PubMed1975

Diagnosis of pregnancy in marmosets (Callithrix jacchus).

3 techniques for studying reproductive function in the marmoset are described. Abdominal palpation was found to be the most successful method for diagnosis of pregnancy. Vaginal cytology and urinary immunoassays met with limited success and were of supportive value only.

Animals↗