Search PubMed⌕ Search

Biomedical subjects

J C Hall

Publications and source records attributed to J C Hall.

At least 289 records · Page 16Linked to original sources
PubMed1984

Identification of a cholinergic synapse in the giant fiber pathway of Drosophila using conditional mutations of acetylcholine synthesis.

Temperature-sensitive mutations of the choline acetyltransferase (Cha) gene, which lead to reduced choline acetyltransferase (ChAT) activity and acetylcholine (ACh) levels, have been used in an attempt to identify the neurotransmitter at a chemical synapse in the giant fiber pathway (GFP) of Drosophila melanogaster. Prolonged incubation of adult mutant flies at non-permissive temperatures blocked the response of this pathway to brain stimulation, whereas shorter incubation times disturbed various parameters of the normal response. Even at permissive temperature subnormal responses were still evident. These defects in the giant fiber pathway's function suggest a specific cholinergic synapse within the pathway, the first synapse of this type implicated in Drosophila. When the function of this synapse was experimentally stressed, disruptions of GFP function paralleling decreased ChAT activity began to appear at enzyme levels estimated to be approximately 80% of wild-type.

Acetylcholine↗
PubMed1984

The cholesterol saturation of bile and its reduction by chenodeoxycholic acid in massively obese patients.

Massively obese patients are at high risk for developing cholesterol gallstones. The objectives of this study were to determine the influence of massive obesity on the cholesterol saturation of bile, and to examine the effect of massive obesity on the ability of chenodeoxycholic acid to decrease biliary cholesterol saturation. Gallbladder bile collected at surgery from massively obese patients was significantly more saturated with cholesterol than bile from non-obese patients who were matched for age, sex and gallstone status (P less than 0.01). Median biliary cholesterol saturation index values for groups of subjects were: no gallstones-not obese (0.83); no gallstones-obese (1.14); gallstones-not obese (1.08); gallstones-obese (1.37). Furthermore, a 5-week course of chenodeoxycholic acid (6 mg/kg/day) was less effective in reducing biliary cholesterol saturation in massively obese patients. The bile of 4 of 10 obese patients remained supersaturated, compared to only one of 10 non-obese patients. These results indicate that biliary cholesterol saturation is raised in massive obesity and that in this condition, the biliary lipid response to chenodeoxycholic acid is diminished. This may explain why obese patients have a relatively poor response to gallstone dissolution therapy with this bile acid.

Adult↗
PubMed1984

Effect of infusion of nutrient solutions into the ileum on gastrointestinal transit and plasma levels of neurotensin and enteroglucagon.

The small bowel transit time of 100 ml of lactulose solution infused at the ligament of Treitz was measured by breath hydrogen excretion in paired studies carried out in 43 healthy volunteers during infusion (1.2 ml/min) of equal volumes (100 ml) of isotonic solutions of either fat emulsion (Intralipid, Prosparol, or Calogen), protein hydrolysate, glucose, or saline into either the jejunum (90 cm from the teeth), ileum (205 cm from the teeth), or colon (350 or 400 cm from the teeth). Ileal infusion of Intralipid or protein hydrolysate resulted in significant delays in small bowel transit time (125 +/- 21 min and 71 +/- 11 min, respectively) compared with infusion of saline (50 +/- 3 min; p less than 0.02 and p less than 0.05). These delays were not associated with any significant alteration in plasma levels of neurotensin or enteroglucagon. Small bowel transit time was unaffected by infusion of nutrients into the colon or jejunum, although jejunal infusion of Intralipid increased the plasma levels of enteroglucagon and neurotensin (p less than 0.01 and p less than 0.02, respectively) after the start of lactulose infusion. In a separate series of paired experiments, infusion of Intralipid into the ileum in 5 volunteers significantly delayed the transit of a solid test meal labeled with 25 microCi of 99mTc-sulfur colloid through both the stomach and small intestine. These data support the existence of a mechanism whereby the presence of unabsorbed food in the ileum may enhance absorption by delaying the passage of food through the small intestine.

Adult↗
PubMed1984

The nutritional knowledge scores of morbidly obese patients selected for gastric bypass surgery.

Repeated attempts at weight-reduction might be expected to coincide with an increase in nutritional knowledge. In this study a 30-item multiple choice test was used to compare the nutritional knowledge of 50 morbidly obese patients, selected for gastric bypass surgery, to that of 50 hospital control subjects prospectively matched for age, sex, educational experience, and socio-economic status. Morbidly obese patients knew less about general nutrition than subjects in the control group (P less than 0.005). In addition there was no significant correlation (rs = 0.10, n = 24) between the amount of weight lost one year after surgery and the nutritional knowledge scores. It seems that whilst morbidly obese patients have a relatively poor level of nutritional knowledge, this finding cannot be related to the extent of weight loss after gastric bypass surgery.

Adult↗
PubMed1983

A method for the rapid assessment of sample size in dietary studies.

Critical readers should be suspicious about the inability of a dietary study to discriminate between the energy intakes of two groups when small sample sizes have been used. The possibility of a false-negative (type II error) should be considered. This problem could be avoided if investigators used adequate sample sizes. A review of 26 dietary studies published in the American Journal of Clinical Nutrition between 1979 and 1981 revealed that the median "SD of energy intakes" was 525 kcal/day. This figure was used to illustrate a simple method for estimating appropriate sample sizes assuming type I and type II error probabilities of 0.05. Prospective use of this method should increase the reproducibility of conclusions drawn from dietary studies.

Calorimetry↗
PubMed1983

Patient well-being after gastric bypass surgery for morbid obesity.

The physical and psychosocial consequences of gastric bypass surgery were observed in 30 morbidly obese patients. Twenty-seven of these patients were satisfied with the results of surgery. Satisfaction was associated with improved health, a better self-image, and greater social activity. Dissatisfaction occurred when an appreciable amount of weight was not lost, or when the patient's expectations about the results of surgery were unrealistic.

Adult↗
PubMed1983

Serum and hepatic enzyme activity in rats treated with diethylnitrosamine.

Comparative studies of enzyme activities during the dedifferentiation of hepatic cells and through their development into overt hepatomas are few and contradictory. This study was designed to investigate the histochemical, biochemical and morphologic features of the altered liver cells with particular emphasis on the importance and validity of the histoenzymatic behavior of glucose-6-phosphatase (G6Pase) as a marker for the detection of precancerous hepatic cells. Serum and hepatic levels of G6Pase were analyzed and compared with the histoenzymatic behavior of this enzyme. The use of other enzymes, such as adenosine triphosphatase (ATPase) and gamma glutamyl-transpeptidase (GGT) as histochemical markers for malignancy was also tested. The activities of a variety of enzymes commonly used as diagnostic tools were also evaluated in both the liver homogenates and sera of rats treated with 2 mg diethylnitrosamine (DENA)/kg body weight for 2-28 weeks. Using G6Pase as a histoenzymatic marker, precancerous cells appeared after 4 weeks of exposure to DENA in the form of small islets devoid of G6Pase activity. These G6Pase free cells increased in number forming larger islands and finally appeared as tumor nodules after 28 weeks of treatment. The histoenzymatic behavior of ATPase was identical to that of G6Pase. The precancerous cells, as well as the tumor cells appeared devoid of ATPase activity. The application of GGT as a marker, showed significantly increased activity in the altered liver and tumor cells. Increased serum levels of G6Pase were noted after 10 weeks and were greatly elevated in the late stages of the evolution of the precancerous cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Cyclic AMP and gastric acid secretion in the dog.

Canine gastric secretions were collected for acid and cyclic AMP assay at zero, 15, 30, 45 and 60 minutes during intravenous infusion of zero, 2.5 and 5.0 micrograms/kg/hr of pentagastrin. A resulting brisk acid response was not accompanied by an elevation of cyclic AMP content. It is thereby suggested that cyclic AMP may not be an obligatory intermediary for gastric acid secretion.

Animals↗