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Biomedical subjects

A Newman

Publications and source records attributed to A Newman.

15 recordsLinked to original sources
PubMed1979

Shark heart mitochondria: effects of external osmolality on respiration.

Shark mitochondrial respiration was studied in media with osmolalities between 160 and 1500 milliosmoles. The respiratory control ratio, a marker for functional integrity of the isolated mitochondria, was maximal at 1000 millismoles and decreased during hypotonic or hypertonic exposure. Shark mitochondria function best at their native tonicity, a value that produces abnormal function in mammalian mitochondria.

Adenosine Diphosphate↗
PubMed1979

Bioenergetic pattern of turtle brain and resistance to profound loss of mitochondrial ATP generation.

The adaptations in the freshwater turtle that permit survival despite prolonged loss of mitochondrial ATP generation were investigated by comparing the bioenergetics of turtle brain slices with rat brain slices. Aerobic turtle brain shows no significant difference in basal levels of total ATP generation compared to rat brain; levels in turtle brain and rat brain were 18.4 +/- 2.8 (SD) and 19.4 +/- 2.2 mumol (100 mg of tissue)-1 hr-1, respectively. However, in turtle brain, a significantly greater fraction of ATP is derived from glycolysis both under aerobic and anaerobic conditions [aerobic turtle (24%) and rat (13%), P less than 0.02; anaerobic, turtle (28%) and rat (18%), P less than 0.05]. The increased glycolytic capacity is related to high levels of rate-limiting glycolytic enzymes, such as pyruvate kinase (EC 2.7.1.40). Turtle brain operates close to glycolytic capacity even under aerobic conditions, and no Pasteur effect can be demonstrated. Quantitatively, anaerobic glycolysis accounts for a maximum of 28% of basal aerobic ATP generation, suggesting that prolonged diving is also accompanied by a reduction in brain energy requirements. The adaptation subserving short-term (natural) diving is an increase in brain glycolytic capacity. The adaptation subserving prolonged diving (days to weeks) may be a reduction in the energy requirements of brain (and other cells).

Animals↗
PubMed1978

Normal findings in oral and cholecystokinin cholecystography.

Normal findings in oral cholecystography and normal response of the gallbladder to cholecystokinin are established in 200 normal controls. These include absence of right upper quadrant pain in 98.5%, absence of spasm of the body of the gallbladder and of severe spasm in the fundus, a common bile duct diameter of 6 mm or less in those 182 that were visualized, and gallbladder size of less than 11 cm in length in about 97% and less than 4 cm in width in about 97%. If normal contraction occurs after cholecystokinin (or sincalide), an unusually large gallbladder is of no importance. Little or no gallbladder contraction in the presence of normal concentration is probably of no importance.

Administration, Oral↗
PubMed1978

Radionuclide test for gastric bile reflux.

The authors conducted a study using radioactive endogenous bile to detect gastric bile reflux in healthy volunteers and patients suspected of having bile gastritis. When 7 muCi of pyridoxylideneglutamate of hydroxyiminodiacetic acid labelled with technetium-99m is injected intravenously it is excreted by hepatocytes, and sequential gamma camera images visualize the bile ducts and show subsequent activity in the gut. Following such an injection, the authors determined the presence of isotope-labelled bile in the stomach in fasting subjects by assaying count rates in serial gastric aspirates obtained by means of a nasogastric tube positioned in the antrum. The results were related to the clinical history and gastroscopic findings. In normal persons only extremely low counts were detected, possibly due to free activity; high counts (in excess of 50 000/min) indicated abnormal reflux. It is suggested that this test is a useful adjunct, and is more physiologic than endoscopy, in the assessment of bile reflux.

Bile↗
PubMed1976

Breath hydrogen in hyposucrasia.

A simple and reliable test for the diagnosis of hyposucrasia is required, since this may be an unsuspected cause of long-standing gastrointestinal disorder. Furthermore little has been done to define the epidemiology of this condition, possibly because of the limitations of multiple blood-sampling. Breath hydrogen (H2) production after lactose ingestion is a reliable test for hypolactasia, and has now been measured after sucrose ingestion in eleven patients with various gastrointestinal symptoms. Six who had normal sucrase activity on jejunal biopsy produced no H2 after taking 50 g of sucrose. No H2 was produced in three patients with borderline hyposucrasia, either after 50 g sucrose or when retested using 100 g sucrose (two patients). However, the two patients with low jejunal sucrase activity showed rises of breath H2, after only 25 g glucose. Breath H2 measurement is a simple, accurate, and non-invasive test for diagnosing gastrointestinal symptoms due to hyposucrasia.

Breath Tests↗
PubMed1975

Breath hydrogen as a diagnostic method for hypolactasia.

Breath hydrogen (H2), collected by end-expiratory sampling, was measured in twenty-five patients with abdominal symptoms or diarrhoea after ingesting 50 g. of lactose. This was compared with established tests of hypolactasia. Fifteen patients with a blood-glucose rise of more than 20 mg. per 100 ml. had less than 4 parts per million (p.p.m.) rise in breath H2 at 2 hours. In contrast, ten patients with blood-glucose rises of less than 20 mg. per 100 ml. had more than a 20 p.p.m. H2 rise (mean 85.8 p.p.m. plus or minus s.d. 44.3) at 2 hours. Similarly, two patients with normal jejunal lactase activity had no significant H2 production, whereas six patients with hypolactasia had more than a 20 p.p.m. rise in H2. Symptoms related to milk or lactose ingestion were found to be unreliable. End-expiratory sampling of breath H2 would seem to be a simple, non-invasive, and accurate method of diagnosing hypolactasia, which is also very acceptable to patients. This should make it a valuable tool both in diagnostic gastroenterology and in epidemiological surveys.

Biopsy↗