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Biomedical subjects

W J Krause

Publications and source records attributed to W J Krause.

At least 73 records · Page 4Linked to original sources
PubMed1989

The cardiac, oxyntic and pyloric glands in the developing opossum (Didelphis virginiana).

In the opossum the fundic area of the gastric mucosa develops first, and oxyntic glands show early division into gastric pits and glandular components which then grow simultaneously. At 40 d postnatum the oxyntic glands are longer than the gastric pits but in the pyloric glands the pits still are longer than the glands and it is not until the 73rd postnatal day, that pyloric glands are longer than their pits. Development of the cardiac glands is delayed even more and the length of the gland does not surpass that of the pit until about 95 d postnatum. Argyrophil cells are concentrated in the cardia and fundus at birth and during early postnatal life, but the population of these cells shifts to the pylorus in the adult. Argyrophil cells of the cardiac, oxyntic and pyloric glands are concentrated in glandular regions with the highest mitotic activity.

Animals↗
PubMed1989

Enteroendocrine cells in the developing opossum small intestine and colon.

Enteroendocrine cells immunoreactive for gastrin, bovine pancreatic polypeptide (BPP), glucagon (glicentin), 5-hydroxytryptamine (5-HT), somatostatin, secretin, motilin, gastric inhibitory peptide (GIP) and cholecystokinin (CCK) are scattered throughout the small intestinal epithelium of the newborn opossum and in all later postnatal stages examined. The number of BPP- and glucagon-immunoreactive cells is relatively high in the newborn and rapidly decreases until only occasional cells are present after the first postnatal week. Cells immunoreactive for GIP, CCK, 5-HT, motilin, gastrin and secretin increase in number with development. Secretin-, motilin-, CCK- and GIP-immunoreactive cells generally are concentrated proximally in the small intestine and as they increase in number, differentiate in more distal regions. The number of gastrin-immunoreactive cells actually decreases just prior to weaning but then increases at and after, weaning. Neurotensin-immunoreactive cells are unusual in that they do not appear until about the 74th postnatal day and then are first encountered in the distal small intestine. As development progresses they increase in number and appear in the more proximal regions. Cells immunoreactive for 5-HT at first increase but then decrease sharply at weaning only to increase markedly again after this time. In contrast, somatostatin-immunoreactive cells gradually decrease in number until weaning then dramatically increase. If the total number of enteroendocrine cells in the small intestine is considered, there is a gradual decrease from birth until weaning when a dramatic increase occurs. Cells immunoreactive for neurotensin, 5-HT and somatostatin are also found in the intestinal epithelium of the developing colon and caecum. Somatostatin- and 5-HT-immunoreactive cells are found throughout the colon in the newborn whereas neurotensin-immunoreactive cells, although observed initially in the proximal colon, do not form a significant population until weaning and then are concentrated distally.

Animals↗
PubMed1988

Salicylate effects on a monolayer culture of gastric mucous cells from adult rats.

Aspirin, acetyl salicylic acid, damages gastric mucosal cells. This effect is considered related to its inhibition of prostaglandin synthesis. On the other hand, sodium salicylate has been reported to be cytoprotective against drug damage to gastric mucosa in vivo. One reason for this difference is that salicylic acid, unlike acetyl salicylic acid does not inhibit prostaglandin synthesis by gastric mucosa in vivo. Previous studies on tissue culture cells from our laboratory have required gastric mucosa from fetal rats; this was time consuming and expensive. The purpose of this study was to develop a primary cell culture of adult rat fundic epithelial cells and to test the effect of sodium salicylate on: (1) prostaglandin (PGE2) production, (2) cell viability, (3) reducing cell damage by sodium taurocholate. Gastric epithelial cells were isolated from adult rat stomachs and cultured on collagen gel. Cells reached confluency on day 4 at which stage fibroblasts were rarely seen (less than 1%). Autoradiographic study showed that cultured cells incorporated [3-H] thymidine into nuclei. In histochemical studies, 94% of the cells contained PAS positive granules (mucous cells). Mucous granules were observed in the cytoplasm of the majority of cells by electronmicroscopy. These cells synthesised prostaglandin E2 as determined by radioimmunoassay. Indomethacin 10(-4) M strongly suppressed PGE2 production after 30 minutes while 10(-3) and 10(-4)M sodium salicylate had no effect. Pharmacologic concentrations of 10 mM sodium salicylate had no effect on PGE2 production at 30 minutes and only weakly inhibited production after one hour incubation. Sodium salicylate up to 30 mM had no effect on cell viability, a concentration of 50 mM being necessary to produce significant cell damage. Sodium salicylate 10 mM significantly protected cells against damage induced by 10 mM sodium taurocholate. We conclude: (i) adult rat gastric mucous epithelial cells can be successfully cultured in vitro; (ii) prostaglandin synthesis is inhibited by indomethacin but not by low doses of sodium salicylate; (iii) sodium salicylate does not damage gastric mucosal cells except at very high concentrations; (iv) sodium salicylate protects against damage to cells induced by sodium taurocholate.

Animals↗
PubMed1988

Indexes of vitamin D deficiency in Japanese quail embryos.

Effects of vitamin D deficiency (-D) on mineral homeostasis were investigated in Japanese quail embryos. The -D embryos from 1,25(OH)2D3-fed hens became progressively calcium deficient, as documented by hypocalcemia and reduced calcium accumulation by the skeleton, yolk sac, and allantoic fluid. Plasma phosphate was progressively elevated between days 11 and 15. Increased calcium accumulation by the skeleton, yolk sac, and allantoic fluid occurred between days 12 and 15 in +D embryos. Phosphate and adenosine 3',5'-cyclic monophosphate (cAMP) concentrations of allantoic fluid increased in +D embryos during the period of shell calcium mobilization. Further increases in phosphate and cAMP excretion into allantoic fluid occurred in -D embryos, although no calcium was absorbed from the shell. Renal 25(OH)D-1-hydroxylase activity increased between days 11 and 13, whereas the adenylate cyclase response to parathyroid hormone was lost in -D embryos by day 14. These changes in renal function are indicative of secondary hyperparathyroidism in the -D embryos. Differentiation of villus cavity and capillary covering cells occurred in the chorionic epithelium of -D embryos, but eggshell calcium was apparently not absorbed. In contrast, 75% of the total body calcium of newly hatched (+D) chicks was obtained from the eggshell. Thus the dissolution and/or transport of eggshell calcium is dependent on vitamin D in quail embryos.

Adenylyl Cyclases↗
PubMed1988

Receptors and cGMP signalling mechanism for E. coli enterotoxin in opossum kidney.

Receptors for the heat-stable enterotoxin produced by Escherichia coli were found in the kidney and intestine of the North American opossum and in cultured renal cell lines. The enterotoxin markedly increased guanosine 3',5'-cyclic monophosphate (cGMP) production in slices of kidney cortex and medulla, in suspensions of intestinal mucosa, and in the opossum kidney (OK) and rat kangaroo kidney (PtK-2) cell lines. In contrast, atrial natriuretic factor elicited much smaller increases in cGMP levels of kidney, intestine, or cultured kidney cell lines. The enterotoxin receptors in OK cells had a molecular mass of approximately 120 kDa when measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of receptors crosslinked with 125I-enterotoxin. The occurrence of receptors for the E. coli peptide in OK implies that these receptors may be involved in the regulation of renal tubular function in the opossum. E. coli enterotoxin caused a much larger increase in urine cGMP excretion (10- to 50-fold over control) than did atrial natriuretic factor when these peptides were injected intravenously into opossums. However, atrial natriuretic factor elicited a marked diuresis, natriuresis, and increased urinary excretion of calcium, phosphate, potassium, and magnesium. In contrast, the enterotoxin did not acutely influence OK fluid and electrolyte excretion. Thus the substantial increase in cGMP synthesis produced by the bacterial peptide in OK cortex and medulla in vitro and the increased renal excretion of cGMP in vivo were not associated with changes in electrolyte or water excretion. Whether cGMP represents a second messenger molecule in the kidney is an interesting question that was raised but not answered in this series of experiments.

Animals↗
PubMed1988

Prostaglandin protection of human isolated gastric glands against indomethacin and ethanol injury. Evidence for direct cellular action of prostaglandin.

Isolated human gastric glands from surgical specimens were preincubated in an oxygenated medium with placebo or 16,16 dimethyl prostaglandin E2 (dmPGE2) and incubated at 37 degrees C in either medium alone, medium containing 4.43 mM indomethacin or medium containing 8% ethanol. We assessed the viability of gland cells with fast green exclusion, release of lactate dehydrogenase (LDH) into the medium, and ultrastructural damage by scanning and transmission electron microscopy. Both indomethacin and ethanol significantly reduced the viability of placebo-pretreated glands, increased LDH release into the medium, and produced prominent ultrastructural damage. DmPGE2 significantly reduced both indomethacin and ethanol-induced injury, increased the number of viable cells, reduced LDH release, and diminished the extent of ultrastructural damage. These studies indicate that PG protection of gastric mucosal cells has a direct cellular action that is not limited to replacement of depleted endogenous PGs. PG protection in our experiments did not depend on PG's previously described systemic actions, such as protection of the microvessels, preservation of the mucosal blood flow, or stimulation of bicarbonate and mucus secretion.

16,16-Dimethylprostaglandin E2↗
PubMed1988

Human cell line for study of damage to gastric epithelial cells in vitro.

UNLABELLED: We evaluated whether monolayers from a well-differentiated human gastric epithelial cell line (MKN 28) are suitable for studying the effect of drugs on gastric mucosa. MKN 28 monolayers and monolayers of human gastric epithelial cells from surgical specimens were studied morphologically and functionally. The protective effect of acetaminophen against taurocholate-induced damage was evaluated as was its effect on prostaglandin production. Both types of cultures showed similar morphologic and histochemical characteristics. Indomethacin inhibited and arachidonic acid stimulated prostaglandin production by both types of monolayers similarly. Both monolayers responded similarly to drug-induced damage. Acetaminophen decreased taurocholate-induced damage by 33% and 40% in MKN 28 cells and in primary human gastric cell culture, respectively. Indomethacin did not prevent acetaminophen protection nor did the amount of prostaglandin produced by cells increase after incubation with acetaminophen. IN CONCLUSION: (1) in the MKN 28 cell line model acetaminophen protected against taurocholate-induced damage; the percentage of protection was similar to that in primary cultures of human gastric epithelial cells; (2) acetaminophen protection in both models was not related to increased prostaglandin production; (3) the MKN 28 cell line is a suitable model to study damage to and protection of gastric epithelial cells in vitro.

Acetaminophen↗
PubMed1988

The effect of surgical ablation of Brunner's glands on the proximal duodenal mucosa.

Neither macroscopic nor microscopic lesions were observed in the gastrointestinal mucosa following the surgical removal of Brunner's glands. This observation leaves some doubt concerning the traditional view that Brunner's glands function primarily in the protection of the proximal duodenal mucosa from acid-pepsin entering from the stomach.

Animals↗
PubMed1988

The portal hypertensive gastric mucosa: histologic, ultrastructural, and functional analysis after aspirin-induced damage.

We assessed macroscopic, histologic, ultrastructural, and functional features of aspirin-induced gastric mucosal injury in portal hypertensive and sham-operated rats. Portal hypertension was produced by staged portal vein ligation. Four hours after intragastric acidified aspirin administration, intraluminal pH in portal hypertensive rats was 6.6 +/- 0.2 and 4.3 +/- 0.5 in sham-operated controls (p less than 0.01). Gross mucosal damage was significantly greater in portal hypertensive rats compared with controls (18 +/- 2 versus 7 +/- 1% of total mucosal area). Histologic deep necrosis involved 22 +/- 2% of mucosal section lengths in portal hypertensive rats compared with 7 +/- 1% in sham-operated rats (p less than 0.01). In portal hypertensive rats, histologic and ultrastructural evaluation demonstrated capillary endothelial abnormalities, arterialization of submucosal veins, and markedly greater severity of microvascular damage than in sham-operated controls. Neutralized aspirin (pH, 7.0) did not produce any significant damage detectable grossly, histologically, or by transmission electron microscopy in portal hypertensive rats. We conclude that acid-dependent aspirin-induced gastric mucosal damage is significantly increased in portal hypertension.

Animals↗
PubMed1987

Opossum adrenal medulla: I. Postnatal development and normal anatomy.

The anatomy and histology of the adrenal gland in the adult opossum were found to be typical for mammals. The development of the adrenal medulla was also found to follow the typical mammalian pattern. Primitive sympathetic cells were found in both intra- and extra-adrenal locations in the newborn at a time when chromaffin precursor cells were migrating to the adrenal anlage. Pheochromoblasts first appeared within the forming medulla where at a later stage chromaffin cells could be observed forming columns of cells between adjacent sinusoids. Unlike in other mammals, much of this development takes place postnatally when the neonate is in the mother's marsupium. The value of the developing opossum adrenal medulla as an experimental model is stressed, since a significant amount of development takes place in an environment that is accessible to experimental manipulation.

Adrenal Medulla↗
PubMed1987

Unique regional distribution of delta 4-3-ketosteroid-5 alpha-oxidoreductase and associated epididymal morphology in the marsupial, Didelphis virginiana.

The epididymal epithelial ultrastructure has been described in the adult male North American opossum, Didelphis virginiana. Morphological results have suggested that absorptive activity is prominent in the proximal epididymal region by virtue of numerous microvilli, an endocytotic complex, dense granules, and multivesicular bodies in the apical cytoplasm. In contrast, the middle and distal epididymal regions exhibit ultrastructural features indicative of protein synthesis such as large invaginated euchromatic nuclei, large nucleoli, and increased amounts of granular endoplasmic reticulum. It is in the middle and distal epididymal regions where sperm head rotation and sperm pairing take place. Epididymal delta 4-3-ketosteroid-5 alpha-oxidoreductase (5 alpha-reductase) activity also has been measured. It has been found that the level of enzyme activity differs significantly (p less than 0.01) between the proximal, middle, and distal epididymal regions. Enzyme-specific activity has been found to be highest in the middle region (47.6 +/- 5.4 picomoles 5 alpha-reduced androgens formed/b/mg protein), lower in the distal region (18.3 +/- 0.7 picomoles 5 alpha-reduced androgens formed/b/mg protein), with little activity (2.4 +/- 1.2 picomoles 5 alpha-reduced androgens formed/h/mg protein) found in the proximal epididymal region. This regional distribution of enzyme activity differs markedly from that reported for eutherian mammals. Both the suggested epididymal protein synthetic and secretory activity and the level of epididymal 5 alpha-reductase activity appear to correlate regionally with the morphological changes that occur in the opossum spermatozoa as they transit the epididymis.

Animals↗
PubMed1987

Immunocytochemical demonstration of gastric endocrine cells in the stomach gland patch of the koala, Phascolarctos cinerus.

The relative frequency and topographical distribution of endocrine cells containing gut hormones were studied by immunocytochemistry in the stomach gland patch of the koala. Numerous somatostatin- and a moderate number of bovine pancreatic polypeptide-immunoreactive cells were found primarily in the lower two-thirds of the oxyntic glands. 5-hydroxytryptamine-immunoreactive cells were few in number and scattered throughout these glands. Glucagon-immunoreactive cells were observed only rarely and then were confined to the basal region of the oxyntic glands.

Animals↗
PubMed1987

Distribution of fibre types in thirty-seven muscles of Didelphis virginiana.

The proportions of Type I and II fibers were determined in 37 muscles of Didelphis virginiana, representing 9 body regions. There was a distinct cranial/caudal gradation in the distribution of Type II fibers throughout the trunk musculature. Muscles of the fore- and hind-limbs showed a gradation of Type II fiber across the width of the muscle, being more prominent at the surface. The type II fibers in the tip of the tail showed peculiar staining properties in which the core of each fiber stained much more lightly than did the periphery.

Adenosine Triphosphatases↗
PubMed1987

16,16-Dimethyl prostaglandin E2 reduced chenodeoxycholate-induced small intestinal mucosal injury in the rat.

To determine whether prostaglandin may protect the small intestinal mucosa against bile acid-induced injury, we perfused in vivo rat jejunal segments with 5 mmol/L chenodeoxycholate with and without topical pretreatment with 2.6 mumol/L (1 microgram/ml) 16,16-dimethyl prostaglandin E2. Mucosal injury by chenodeoxycholate and its time sequence was assessed by using mannitol absorption and quantitative histology after 5, 15, 30, and 45 minutes of chenodeoxycholate perfusion. Forty-five-minute perfusion with chenodeoxycholate increased mannitol absorption from 0 to 0.9 nmol/min/cm, whereas prostaglandin pretreatment reduced this increase threefold (P less than 0.001). The increase in mannitol absorption coincided with progressive denudation of epithelial cells from intestinal villi. After 45 minutes exposure to chenodeoxycholate, an average of 50 micron of the cross-sectional surface of the villi tips was denuded of epithelial cells compared with only 25 micron denuded with prostaglandin pretreatment (P less than 0.01). These data indicate that topical administration of 16,16-dimethyl prostaglandin E2 reduces both the functional and morphologic small intestinal mucosal injury caused by chenodeoxycholate.

16,16-Dimethylprostaglandin E2↗
PubMed1987

An immunohistochemical survey of gastric proteinase (pepsinogen and prochymosin)-containing cells in the stomach of the developing opossum (Didelphis virginiana).

Cells immunoreactive to antisera of bovine pepsinogen and prochymosin are seen in the oxyntic glands but not the pyloric or cardiac glands of the opossum. Immunoreactivities to pepsinogen and prochymosin occur within the same cell and are restricted to an undifferentiated cell type prior to weaning. The undifferentiated cells producing these gastric proteinases decrease in number until just prior to weaning and disappear with the appearance of chief cells. Thereafter, immunoreactivities to both gastric proteinases are seen primarily in chief cells.

Animals↗
PubMed1986

Does sucralfate affect the normal gastric mucosa? Histologic, ultrastructural, and functional assessment in the rat.

Although the action of sucralfate on ulcerated mucosa has been demonstrated, its effect on the histology, ultrastructure, and function of normal gastric mucosa is unknown. We investigated the effect of acute administration of sucralfate on the gastric mucosal history, ultrastructure, mucosal potential difference, and luminal release of prostaglandin E2. At 15 min, 1 h, and 3 h after intragastric instillation of sucralfate, whitish incrustations of the drug were firmly adhering to the glandular mucosa. Mucosal histology after sucralfate administration demonstrated the following: disruption and exfoliation of some of the surface epithelial cells, mucosal hyperemia, prominent release of mucus from the surface epithelial cells, and edema of lamina propria and submucosa. These changes were most prominent in the areas where sucralfate was in contact with the mucosal surface. Scanning and transmission electron microscopy confirmed the above changes. Sucralfate produced a drop in gastric mucosal potential difference and a significant increase in luminal release of prostaglandin E2. Sucralfate produces distinct morphologic and functional changes in the normal gastric mucosa, which may account for its preventive and therapeutic efficacy.

Aluminum↗
PubMed1986

Enteroendocrine cells in the developing opossum stomach.

The distribution of enteroendocrine cells showing immunoreactivities to four peptides and one amine was examined in the gastric mucosa of the opossum during postnatal development using specific immunocytochemical methods. Gastrin-, BPP-, glucagon-, somatostatin- and 5-HT-immunoreactive cells were identified in the gastric mucosa of the newborn opossum. Gastrin-immunoreactive cells were restricted to the epithelial lining of the pylorus; glucagon-immunoreactive cells were seen only in the epithelium of the fundus. Somatostatin- and 5-HT-immunoreactive cells were found in the epithelium of both fundic and pyloric regions. BPP-immunoreactive cells were the most numerous endocrine cell type seen in the gastric epithelium of the newborn opossum and although found mainly at the confluence of the fundic and pyloric regions, were confined primarily to the fundus in the one week old opossum and all older animals. A marked increase in all five immunoreactive cell types was seen by the end of the first postnatal week. Gastrin-immunoreactive cells were the most numerous at this time and exceeded adult numbers. Both glucagon- and BPP-immunoreactive cells were confined to the fundic glands of older animals and showed the same pattern of decline with age. Somatostatin- and 5-HT-immunoreactive cells showed a shift in population from the fundus to the pylorus with age and together with gastrin-immunoreactive cells were restricted to a narrow zone at the bottoms of the gastric pits and the upper parts of the pyloric glands.

Animals↗