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Biomedical subjects

M D Levitt

Publications and source records attributed to M D Levitt.

At least 163 records · Page 9Linked to original sources
PubMed1981

Prevalence and nature of hyperamylasemia in acute alcoholism.

Determination of serum amylase activity in 100 consecutive patients admitted to an alcohol detoxification unit revealed hyperamylasemia in 39 cases. Further clinical evaluation of 15 of the 39 alcoholic patients with hyperamylasemia was unremarkable except for bilateral enlargement of the parotid glands in two cases. Nine of the 15 patients demonstrated markedly low amylase to creatinine clearance ratio; however, macroamylase complexes were not detected in the sera of any patients. Serum isoamylase separation revealed that the mean salivary isoamylase for the 15 alcoholic patients was significantly (P less than 0.05) elevated as compared to the control values. Individually, the salivary-type isoamylase was clearly elevated in ten patients while pancreatic type isoamylase was elevated in four. These data indicate that elevated serum amylase activity occurs frequently in alcoholic patients. Hyperamylasemia in a large number of alcoholic patients is nonpancreatic in origin and may be related to the injurious effect of ethanol on salivary glands and other tissues.

Acute Disease↗
PubMed1981

Study of the possible enteropancreatic circulation of pancreatic amylase in the dog.

The possible existence of an enteropancreatic circulation of amylase was investigated in the dog. Endogenous amylase concentration in pancreatic venous blood was consistently greater than that in arterial blood, indicating a net flux of amylase from the pancreas to blood. Less than 0.02% of the metabolic clearance of 125I-amylase was accounted for by 125I-amylase in pancreatic secretions, indicating a minimal flux of amylase from the blood to pancreatic secretions. The venous-arterial amylase concentration across gut segments containing large quantities of amylase was not significantly different from 1.00, indicating absorption of less than 0.2% of the luminal amylase per hour. No 125I-amylase was detectable in serum after endoscopic instillation of labeled enzyme into the duodenum. These studies demonstrate negligible intestinal absorption of amylase and negligible pancreatic extraction of amylase, indicating negligible enteropancreatic circulation of pancreatic amylase in the dog.

Amylases↗
PubMed1980

Milk intolerance in Manitoba Indian school children.

The breath H2 test was used to determine the prevalence of milk intolerance in Indian schoolchildren, 5 to 19 years old. One hundred four children were randomly assigned to one of six groups: 1) reconstituted skimmed milk powder (SMP); 2) SMP and sandwich; 3) SMP and lactase; 4) diluted (1:1) evaporated whole milk (EM); 5) EM and sandwich; and 6) EM and lactase. Samples of expired air were collected 2 hr after ingestion of 245 ml of milk. Five children had H2 levels suggestive of appreciable lactose malabsorption; two had symptoms. The mean H2 excretion levels of the subjects on SMP were significantly higher than those on EM. The group on SMP alone excreted significantly more H2 than any other group except those receiving SMP and a sandwich. The relatively low prevalence of milk intolerance in this populatin group should not preclude continuation and promotion of milk programs in their schools. However, preference should be given to the use of EM rather than SMP. The needs of children who cannot hydrolyze lactose must also be considered in the planning of food supplement programs.

Adolescent↗
PubMed1980

Flatulence.

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Carbon Dioxide↗
PubMed1980

Effect of glucagon on gastrointestinal blood flow of dogs in hypovolemic shock.

A microsphere technique was used to study the effect of glucagon on blood flow to the different tissue layers of the stomach, small bowel, and colon of the dog in hypovolemic shock. In normal dogs, glucagon caused a twofold rise in flow to all layers of the stomach and colon, and a threefold increase to all layers of the small bowel. After administration of glucagon, a larger fraction of cardiac output was diverted to the gut microcirculation. In acute hypovolemic shock, intestinal perfusion was preserved relative to cardiac output inasmuch as cardiac output and gastric blood flow fell 75% and flow to the small bowel and colon fell by only about 50%. Glucagon markedly increased the fraction of cardiac output passing to the gut circulation in hypovolemic shock and, most importantly, sustained flow to the areas most prone to ischemic necrosis; gastric mucosa, colonic mucosa, and small intestinal villi. In more prolonged shock, however, glucagon precipitated fatal cardiovascular collapse unless part of the lost blood volume first was replaced. Glucagon, therefore, should not be used in patients in hypovolemic shock without prior replacement of at least part of the lost blood volume.

Animals↗
PubMed1980

Use of a model of small bowel mucosa to predict passive absorption.

The purpose of this study was to determine if the observed rate of passive absorption of inert gases from the canine small bowel could be predicted by the use of an anatomical model of the mucosa and measurements of villus blood flow and the diffusive barrier to absorption. Villus blood flow was measured with microspheres and the diffusive barrier separating bulk luminal contents and blood was estimated from CO absorption. The model predicts initial uptake of the inert gases (H2, He, CH4, and 133Xe) in blood at the villus tip, subsequent countercurrent exchange in the villus, and longitudinal diffusion of the gases down the villus to a subvillus blood flow. Observed absorption rates for each of these four gases were reasonably accurately predicted by the model at both basal villus blood flow and at low villus blood flow induced by hypotension. We suggest that this model can be used to predict passive absorption kinetics over a range of villus blood flows and to predict the influence of a variety of parameters on the rate of passive absorption of diffusible substances.

Animals↗
PubMed1980

Colonic conservation of malabsorbed carbohydrate.

[14C]Sucrose absorption was studied in 4 healthy controls and 4 patients after jejunoileal bypass using an ileal perfusion technique which made it possible to distinguish 14C-absorption in the small bowel from that occurring in the colon. Healthy controls failed to absorb 2--4% of a 50-g dose of [14C]sucrose in the small bowel; however, virtually none of the [14C] appeared in feces in a dialyzable form with appreciable osmotic activity. In bypass patients, the small bowel failed to absorb 29--84% of the 50-g dose of [14C]sucrose. Approximately two-thirds of the nonabsorbed [14C] was in the form of sucrose and the remainder was nearly all present as monosaccharides. A mean of only 42% of the [14C] Not absorbed in the small bowel appeared in the feces and only about one-third of this fecal [14C] was in a dialyzable form with appreciable osmotic activity. Thus, the colon plays an important role in carbohydrate malabsorption by salvaging carbohydrate and reducing osmotic activity of the nonabsorbed sugar. This conlonic function appears to depend upon bacterial metabolism of the carbohydrate, and individual variations in diarrhea and weight loss associated with carbohydrate malabsorption could reflect individual differences in the bacterial flora of the colon.

Adult↗
PubMed1980

The effect of anesthesia and laparotomy on blood flow to the stomach, small bowel, and colon of the dog.

The effect of anesthesia and laparotomy on the distribution of blood flow to the different tissue layers of the stomach, small bowel, and colon of the dog was studied using a double-isotope, microsphere technique. In conscious dogs total jejunal flow significantly exceeded both ileal and colonic flow. Mucosal flow comprised about two thirds of total gastric and small bowel flow, but less than half of colonic flow. Fifteen minutes after induction of anesthesia, there was a marked increase in flow to all levels of the alimentary tract, as well as to each tissue layer. This increase was transient, since by 1 hour flow to all gut levels had decreased nearly to baseline levels. Laparotomy per se did not significantly alter blood flow to the full thickness or mucosal layer of either stomach, small bowel, or colon. These findings indicate that future studies of gut function or blood flow should be performed in conscious animals or in anesthetized animals only after complete cardiovascular stabilization. Neither laparotomy nor anesthesia caused a redistrubtion of flow away from the mucosal layers, and hence the observation that patients have often stopped bleeding at the time of operation for uncontrolled hemorrhage is unexplained.

Anesthesia, General↗
PubMed1979

Follow-up of a flatulent patient.

This paper describes a low-flatulence diet developed by an extremely flatulent patient. Based on meticulous recording of each passage of flatus, the patient employed an elimination diet to determine what foods were responsible for his gas production. The diet reduced the frequency of his gas passage from 34 +/- 7 to 17 +/- 5 times per day (normal: 14 +/- 6) and similar reductions were observed by two other flatulent patients during adherence to the diet. The rectal gas of each of these subjects largely consisted of two gases (CO2 and H2) which result from bacterial fermentation of carbohydrates. The diet, which is low in lactose and wheat products, presumably minimizes the quantity of carbohydrates delivered to the colonic bacteria.

Adult↗
PubMed1979

Use of microspheres to measure small intestinal villus blood flow in the dog.

The accuracy of using 7- to 10-micron microspheres to measure blood flow to dog small intestinal villi was studied. These spheres appear to pass unimpeded through the afferent arterioles of the villus and lodge at the villus tip because 1) virtually all villus spheres were located at the tip, 2) flow determined by visually counting spheres did not differ significantly from flow determined from radioactivity of the sheared-off villus layer, 3) the size distribution of spheres in the villus and subvillus layers was virtually identical to that administered, indicating no premature impaction of the larger spheres, and 4) spheres lodging in the submucosa during vasoconstriction did not subsequently migrate to the villi during vasodilatation. Studies with 25-micron spheres indicated that 28% of the 7- to 10-micron spheres shunted through vessels greater than 10 micron. Double isotope studies showed that lodges spheres do not migrate and that the injection of 2--4 X 10(6) spheres does not alter villus flow. Thus, 7- to 10-micron microspheres pass to and lodge in villus vessels in proportion to capillary flow and should provide an accurate estimate of villus nutrient blood flow.

Animals↗
PubMed1979

Clinical use of amylase clearance and isoamylase measurements.

Isoamylase determinations and measurements of the ratio of the renal clearance of amylase relative to creatinine (CAm/CCr) were employed in an attempt to improve the diagnostic accuracy of the standard amylase measurement. An elevated CAm/CCr reflects defective proximal tubular reabsorption of amylase which occurs in virtually all patients with clear-cut acute pancreatitis. However, other conditions that apparently are associated with acute defective tubular function, such as burns and diabetic acidosis, may cause an elevated ratio. Thus, elevations of CAm/CCr cannot be considered to be specific for acute pancreatitis. Pancreatic isoamylase represents, on the average, about 33% of the normal serum amylase activity, whereas about 66% is salivary-type isoamylase. Isoamylase measurements are useful in determining whether an elevated value for serum amylase activity is of pancreatic origin. However, this measurement is not useful for determining whether patients with normal serum amylase activity have pancreatitis.

Amylases↗
PubMed1979

Postoperative elevation of amylase/creatinine clearance ratio in patients without pancreatitis.

An elevated CAm/CCr ratio has been used as evidence for the frequent occurrence of acute pancreatitis in the postoperative period. We measured CAm/CCr pre and postoperatively in 28 patients undergoing extraperitoneal surgical procedures. None of the patients had clinical evidence of pancreatitis, although 2 of the 28 patients had elevated CAm/CCr ratios preoperatively. Mean CAm/CCr rose from a preoperative level of 2.3 +/- 0.3% (1 SE) to 3.2 +/- 0.3% on the first postoperative day (P less than 0.001). Of the 26 patients with normal preoperative CAm/CCr, 12% (3 of 26) developed a clearly abnormal ratio and 12% (3 of 26) developed borderline elevated values. An elevated CAm/CCr appears to be a nonspecific postoperative finding and cannot be used as evidence of acute pancreatitis during this period.

Amylases↗