PubMed Health⌕ Search

Biomedical subjects

D B Morton

Publications and source records attributed to D B Morton.

At least 19 recordsLinked to original sources
PubMed1992

Pancreatic function following partial pancreatectomy and anastomosis of the pancreatic duct to the stomach or duodenum in dogs.

The effects of pancreatic duct anastomosis to stomach (stomach group) or duodenum (duodenal group) on pancreatic function were examined in dogs following two thirds pancreatectomy. Normal fasting blood glucose concentrations were maintained in both groups despite significant reductions in glucose tolerance in the stomach group, and reductions in fasting insulin and insulin peak response in both groups. Pancreatic exocrine function was significantly decreased in both groups, though plasma p-aminobenzoic acid (PABA) concentrations were generally higher in the duodenal group. A correlation was found between plasma trypsin-like immunoreactivity (TLI) and pancreatic weight. These results indicate that anastomosis of the pancreas to bowel can be undertaken with minimal postoperative complications and that the site of the anastomosis influences pancreatic function. They suggest that preservation of more than one third of the pancreas is required for optimal function. The complementary information provided by the PABA and TLI tests suggests their dual application will be clinically useful for the detection and characterisation of naturally occurring pancreatic diseases.

4-Aminobenzoic Acid↗
PubMed1992

Eclosion hormone stimulates cyclic GMP levels in Manduca sexta nervous tissue via arachidonic acid metabolism with little or no contribution from the production of nitric oxide.

The neuropeptide eclosion hormone acts directly on the nervous system of the tobacco hornworm, Manduca sexta, to trigger ecdysis behavior at the end of each molt. Previous studies have shown that the action of eclosion hormone is mediated via the intracellular messenger cyclic GMP. In the present study we have investigated the mechanisms involved in the eclosion hormone-stimulated increases in cyclic GMP. No stimulation of guanylate cyclase was seen in homogenized nervous tissue, suggesting that eclosion hormone does not directly stimulate a membrane-bound form of guanylate cyclase. Nitric oxide synthase inhibitors, N-methylarginine and nitroarginine, had no effect on eclosion hormone-stimulated cyclic GMP levels. By contrast, 4-bromophenacyl bromide, an inhibitor of arachidonic acid release, and nordihydroguaiaretic acid, an inhibitor of arachidonic acid metabolism, almost completely abolished the eclosion hormone-stimulated cyclic GMP increase. We hypothesize that eclosion hormone receptors are coupled to a lipase, activation of which causes the release of arachidonic acid. Either the arachidonic acid directly stimulates the soluble guanylate cyclase or further metabolism of arachidonic acid yields compounds that activate guanylate cyclase.

Animals↗
PubMed1992

The HID50 (hypothermia-inducing dose 50): an alternative to the LD50 for measurement of bacterial virulence.

A group of 40 mice involved in bacterial LD50 estimations was monitored over a period of 4 days by two teams of observers. One team measured the colonic temperature of the mice, the other assessed them clinically and killed those they judged terminally ill. The temperatures of all mice considered terminally ill dropped before this judgement was made. Measurement of such infection-induced hypothermia provides a more objective, reproducible, and earlier endpoint than that used in conventional LD50 estimation.

Animals↗
PubMed1991

Effect of pancreatectomy on plasma activities of amylase, isoamylase, lipase and trypsin-like immunoreactivity in dogs.

The contribution of the pancreas to the plasma activities of amylase, isoamylase, lipase and the concentration of trypsin-like immunoreactivity (TLI) in the dog was examined by measuring the activities of these enzymes before and after total pancreatectomy. Pancreatectomy was followed by a decrease in the concentration of TLI (from 6.2 +/- 0.3 micrograms litre-1 to 1.2 +/- 0.3 micrograms litre-1; P less than 0.001) and activity of isoamylase peak 4 (from 1257 +/- 105 iu litre-1 to 894 +/- 171 iu litre-1; P less than 0.05). Though significantly reduced, the activities of peak 4 isoamylase were still within the normal range for control dogs. Pancreatectomy did not significantly alter the activities of amylase, lipase or isoamylase peaks 1, 2 and 3. These findings provide strong evidence that the pancreas is not the sole source of circulating amylase, isoamylase and lipase activities. In contrast the marked reductions in TLI to values close to the limits of assay sensitivity suggest that TLI is derived from the pancreas alone. The results indicate that assay of circulating TLI provides a more sensitive and specific indicator of pancreatic exocrine mass than plasma amylase, lipase or isoamylase activities.

Amylases↗
PubMed1990

Homoeopathy.

Explore the source record for details and available documents.

Animals↗
PubMed1990

Effects of exocrine pancreatic insufficiency and replacement therapy on the bacterial flora of the duodenum in dogs.

The influence of pancreatic secretions on the bacterial flora of the small intestine in 6 dogs was investigated by determining effects of exocrine pancreatic insufficiency on numbers and types of bacteria in duodenal juice, and by examining the subsequent response to dietary supplementation with bovine pancreatic extract. Exocrine pancreatic insufficiency was induced by ligation of pancreatic ducts and was confirmed by indirect assessment of exocrine pancreatic function. Duct ligation was followed by large increases (P less than 0.01) in total numbers of bacteria, reflecting increased numbers particularly of Lactobacillus spp and Streptococcus spp, in 3 dogs accompanied by obligate anaerobes. Total numbers of aerobes and anaerobes decreased markedly (P less than 0.05) after supplementation with bovine pancreatic extract to values that were not significantly different from those determined before duct ligation. Exocrine pancreatic insufficiency therefore resulted in small intestinal bacterial overgrowth that was reversed by pancreatic replacement therapy, indicating that pancreatic secretions can have an important influence on the small intestinal bacterial flora of dogs.

Animals↗
PubMed1989

The use of a biological adhesive to achieve sutureless epikeratophakia.

An adhesive made of concentrated human fibrinogen produced from samples of single donor blood by a simple cryoprecipitation method was tested for its ability to bond lamellar corneal buttons in vitro and found to have a bond strength of 140 gm/cm2. The adhesive was successfully used to attach experimental epikeratophakia grafts in a rabbit model. The results were similar to those reported from an earlier trial using a commercially available adhesive prepared from pooled multi-donor human plasma. This experimental trial of single-donor adhesive demonstrates the possibility of successful use of autologous fibrinogen adhesive in human epikeratophakia. Autologous adhesive would remove the possible threat of transmitted disease posed by multi-donor adhesive and avoid immune reactions to foreign proteins.

Animals↗
PubMed1989

DNA fingerprinting of spontaneously hypertensive and Wistar-Kyoto rats: implications for hypertension research.

Probes to hypervariable minisatellite regions of DNA identify multiple loci scattered over the autosomal chromosomes and produce a complex Southern blot pattern of fragments termed a DNA 'fingerprint'. As concern has been raised that different stocks of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) may not be biologically identical, we have compared the DNA of SHR and WKY from several sources using two such probes which identify different sets of minisatellite sequences. While the DNA fingerprints of SHR from the various sources were identical, variability was observed in those of WKY, indicating genetic heterogeneity between different WKY stocks. In animals from one of the commercial suppliers even inter-rat variability in DNA fingerprints was seen, suggesting genetic heterogeneity within that single colony. These observations indicate that experimental results obtained using WKY from different sources may not be directly comparable and could provide an explanation for some of the conflicting data that exist on the comparative characteristics of SHR and WKY. In separate studies, direct comparisons both of the DNA fingerprints of SHR and WKY and of SHR and stroke-prone spontaneously hypertensive rats (SHRSP) showed multiple differences between the strains. The polymorphisms seen could provide useful linkage markers in locating the chromosomal sites of the genetic loci responsible for raised blood pressure in the SHR and the propensity to strokes in the SHRSP.

Animals↗
PubMed1989

Identification and characterization of a pancreatic intrinsic factor in the dog.

An intrinsic factor has been identified in the canine pancreas, and output and properties of this protein have been compared with those of gastric intrinsic factor in the dog. Mean concentrations of intrinsic factor and peak outputs per minute were approximately 5- to 10-fold higher in pure pancreatic juice after stimulation with secretin and cholecystokinin, respectively, than in pentagastrin-stimulated gastric juice. Purified gastric and pancreatic intrinsic factors had an identical molecular mass of 65 kDa, estimated by gel filtration on Sephacryl S-200, while sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated single bands corresponding to 53 kDa. Immunoblots showed that rabbit polyclonal antiserum to canine gastric intrinsic factor cross-reacted with canine pancreatic intrinsic factor. Gastric and pancreatic intrinsic factor-cyano[57Co]cobalamin complexes exhibited comparable association constants for ileal receptors in canine brush-border vesicles, while there was minimal binding to jejunal vesicles. These findings demonstrate that the canine pancreas is an important source of an intrinsic factor that closely resembles gastric intrinsic factor in the dog.

Animals↗
PubMed1989

Circulating concentrations of trypsin-like immunoreactivity and activities of lipase and amylase after pancreatic duct ligation in dogs.

The possibility that assay of circulating trypsin-like immunoreactivity (TLI) could assist in the diagnosis of acute pancreatitis in dogs has been examined by assaying plasma TLI concentrations after pancreatic duct ligation and comparing the results with plasma activities of lipase and amylase. Venous blood samples were obtained from 8 dogs before surgery, then daily for 5 days and at 14 days after ligation of pancreatic ducts. Plasma concentrations of TLI increased within 24 hours and tended to peak before and to decrease more rapidly than activities of lipase and amylase, remaining greater than the control range for 5 days in all but 2 dogs. Plasma lipase and amylase activities increased together and remained greater than the control range in all dogs for 5 days after surgery. Regression analysis of all postoperative data indicated significant correlations between concentration of TLI and lipase activity (r = 0.67, P less than 0.001), concentration of TLI and amylase activity (r = 0.53, P less than 0.001), and between lipase and amylase activities (r = 0.74, P less than 0.001). These findings suggested that assay of TLI may provide an early indication of acute pancreatitis in dogs. Because TLI is specifically pancreatic in origin, high plasma TLI concentration may prove a more reliable indicator of clinical pancreatitis than high activities of amylase or lipase, which may be derived from extrapancreatic tissues.

Amylases↗
PubMed1989

Biochemical changes in the jejunal mucosa of dogs with exocrine pancreatic insufficiency following pancreatic duct ligation.

The effects of exocrine pancreatic insufficiency on the small intestinal mucosa were examined in dogs following pancreatic duct ligation. There were no significant changes either in villus architecture or enterocyte height after duct ligation, but numbers of bacteria in duodenal juice increased then subsequently decreased following treatment with exogenous pancreatic enzymes. Pancreatic insufficiency resulted in a considerable increase in the proportion of microvillar membrane proteins of molecular mass over 200 kDa from 3.3 +/- 4 per cent (mean +/- SEM) to 13.6 +/- 7.2 per cent, and this decreased to 6.9 +/- 5.2 per cent following pancreatic enzyme supplementation. However, anticipated increases in activities of maltase and sucrase were not observed following duct ligation, and there was a reduction in lactase activity which was reversed by pancreatic supplementation. Activities of marker enzymes for the other subcellular organelles showed relatively minor or no changes throughout the study. These findings are consistent with a specific role for pancreatic enzymes in the post-translational processing of intestinal microvillar membrane proteins, and suggest that reduced degradation of brush border proteins in the absence of pancreatic secretions may be masked by quantitative and qualitative changes in the intestinal microflora.

Alkaline Phosphatase↗