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Biomedical subjects

E Urban

Publications and source records attributed to E Urban.

At least 37 records · Page 2Linked to original sources
PubMed1984

Copper absorption by remnant small bowel after extensive intestinal resection in the rat.

Rats were subjected to 50% proximal or 50% distal small bowel resection or sham operation. Four weeks later intestinal absorption of copper was measured in vivo using a recirculation technique. In each rat 10 cm in situ segments of duodenum, midgut, and ileum were perfused through the lumen for 2 h with 15 ml of an isotonic solution containing 2 micrograms/ml copper together with 14C-polyethylene glycol as volume marker. Absorption was expressed per g dry mucosa and per cm segment length. After proximal enterectomy absorption of copper per g mucosa decreased in the duodenum and midgut but remained unchanged in the ileum compared to sham-operated controls. However, there were adaptive increases in mucosal mass in all segments. Copper absorption per cm segment length in duodenum and midgut remained unchanged from controls and ileal absorption per cm increased in proportion to mucosal growth. After distal enterectomy absorption of copper per g mucosa remained unchanged in the duodenum but decreased in the midgut and ileum compared to sham-operated controls. Adaptive mucosal growth now occurred only in the midgut and ileum. In the ileum mucosal mass more than doubled. Copper absorption per cm segment length in the duodenum and midgut did not change from controls. However, in the ileum absorption per cm increased above that of controls because of the marked mucosal growth. Therefore, in response to either proximal or distal small bowel resection, the ileum was the site for adaptive copper absorption but adaptive mechanisms differed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1984

In vivo zinc transport by rat small intestine after extensive small bowel resection.

We studied the effects of intestinal resection on in vivo zinc transport and intestinal tissue zinc in remnant duodenum and ileum 4 wk after two-thirds small bowel enterectomy. In situ duodenal and ileal intestinal segments from resected and sham-operated control rats were perfused through the lumen with an isotonic solution containing 0.077 mM zinc with isotopic 65Zn as tracer. After resection there was significant mucosal growth in both segments, but segment transport specific activities (transport per gram mucosa) were unchanged. Therefore, increased segment transport capacities (transport per centimeter segment length) in both segments approximated increased mucosal mass. Comparisons with transport data from our earlier studies on other luminal substrates in rats after small bowel resection showed that adaptive transport mechanisms vary not only with the luminal substrate examined but may also differ in remaining proximal and distal small bowel. In the present study about 12% of the absorbed radiotracer zinc remained in the intestinal wall after perfusion of both duodenum and ileum of resected and control animals, and there were no effects of resection on tissue radiotracer 65Zn concentrations or specific activities in the mucosal fraction or underlying tissues. Calculations of mucosal entry and exit fluxes per centimeter segment length showed that the major effect of resection was to increase the zinc entry flux at the luminal surface of the mucosa. At the basal surface of the mucosa, both entry and exit fluxes increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1983

Morphologic and functional adaptations of large bowel after small-bowel resection in the rat.

Seventy percent small bowel was resected in rats. Two and four weeks later transport of sodium, chloride, and water was examined in cecum and more distal large bowel (colon) using a well-established in vivo luminal perfusion technique. Sham-operated and unoperated rats served as controls. In cecum mucosa grew 29% by two weeks after resection but transport remained unchanged. There were no further adaptive changes by four weeks after resection. Unexpectedly, cecum of all rats secreted water and electrolytes. The mechanism remains unclear. In colon there were no adaptive changes by two weeks after resection but by four weeks colon mucosa increased 14% and luminal absorption increased proportionately. Separate studies showed hexose transport could not be induced in cecum or colon, although we have previously demonstrated its induction in contiguous remnant ileum.

Animals↗
PubMed1983

Separation of adaptive mucosal growth and transport after small bowel resection.

In rats 70% of the small bowel was resected with preservation of duodenum and terminal ileum. Two and four weeks later transport of sodium, chloride, water, and galactose was studied in duodenum and ileum. Controls were sham-operated and unoperated rats. There was significant mucosal growth 2 and 4 wk after resection. By 2 wk postresection transport specific activities (transport per gram mucosa) were generally decreased. Mucosal growth compensated only sufficiently so that transport capacities (transport per centimeter segment length) remained unaltered from controls. By 4 wk postresection transport specific activities had either increased or were unchanged from controls. Therefore, in association with mucosal growth, transport capacities increased. The major adaptive increases for electrolytes and water occurred in duodenum; ileum was the site of increased galactose transport. The data indicate that 1) mucosal growth and functional transport changes occur as separate adaptive phenomena and 2) adaptive transport mechanisms are selectively localized to particular regions of the intestine.

Animals↗
PubMed1983

Permeability of polyethylene glycol in remnant small bowel after massive intestinal resection.

Studies were designed to determine if permeability of adapted (remnant) small bowel mucosa to polyethylene glycol (PEG) was altered after major intestinal resection. Rats underwent 50% small bowel resection with preservation of duodenum and terminal ileum. Sham-operated animals served as controls. Two and four weeks later we cannulated the portal vein and measured mucosal permeability to luminal [3H]PEG and [14C]PEG in isotonic Ringer solution in remnant proximal or distal in situ closed intestinal loops. A lumen-to-portal blood gradient of at least 1000/1 persisted throughout the one-hour experimental period in both resected and sham-operated animals. Thus the adapted remnant intestinal mucosa was highly impermeable to luminal radiotracer PEG. In separate experiments 2 and 4 weeks after 70% small bowel resection or sham operation, in vivo segments of proximal and distal small intestinal were perfused through the lumen for one hour with hypertonic (800 mOsm) mannitol or NaCl solution containing [3H]PEG. There was equal and almost total recovery of [3H]PEG at the end of the experimental period in resected and control animals. The combined data of all experiments indicate that radiotracer PEG may be confidently used as a luminal water phase marker in transport studies of remnant bowel following intestinal resection.

Animals↗
PubMed1982

Permeability of adolescent rat intestine to pancreatic ribonuclease.

There are indications that exocrine pancreatic enzymes may undergo an enteric recirculation. Ribonuclease (RNase) is present in considerable quantities in pancreatic exocrine secretions. Therefore we studied the intestinal transport of pancreatic RNase using everted gut sacs from duodenum, midgut, and ileum of young rats. Gut sacs were incubated aerobically at 37 degrees C, 22 degrees C, and 0 degrees C, and anaerobically at 37 degrees C. Measurable amounts of RNase crossed the intestinal barrier, but neither duodenum, midgut nor ileum absorbed RNase preferentially. The experimental data favor simple diffusion of RNase across rat small bowel. However, the amounts of pancreatic RNase absorbed were small. Thus, while our data do not negate the concept of an enteropancreatic recirculation in the rat, only a minor quantity of luminal, pancreatic RNase could recirculate.

Animals↗
PubMed1982

Calcium metabolism in young rats during early dietary phosphate deprivation.

A series of in vivo experiments were designed to study the early effects of phosphate depletion on calcium metabolism in young adult (8-10 week old) rats with intact thyroid--parathyroid glands. Hypercalciuria occurred within 24 h of dietary phosphate deprivation. It was the consequence of mobilization of calcium stores from the exchangeable calcium pool of the diaphysis of bone. Increased net intestinal absorption of calcium also occurred early. This was at least in part due to decreased net intestinal secretion of calcium into the gut lumen. Thus the early onset of hypercalciuria and hypercalcemia associated with Pi deprivation in normal growing young rats is the combined result of increased net intestinal calcium absorption and increased calcium mobilization from bone.

Age Factors↗
PubMed1982

In vivo absorption of pancreatic ribonuclease from the small intestine of young and mature rats.

It has been postulated that exocrine pancreatic enzymes may undergo an enteropancreatic recirculation as a mechanism for the conservation of digestive enzymes. Exocrine pancreatic secretions contain considerable amounts of ribonuclease (RNase). Therefore we examined the absorption of RNase from the small bowel of 4-week and 10-week-old rats by measuring concentration changes of the substrate in portal blood after instilling RNase into in vivo, in situ intestinal loops. Unphysiologically high intestinal luminal RNase concentrations were required for sufficient RNase to cross the mucosal barrier and raise portal vein blood RNase levels. A gradient of 1,000:1 existed between intestinal lumen and portal vein blood RNase concentrations in the 4-week-old rats. The gradient was 10 times greater in the mature animals. No significant differences in luminal absorption of RNase from duodenum or ileum were detected. The data indicate that RNase penetrates the intestinal mucosa in vivo but that only small amounts are absorbed. Therefore if an enteropancreatic recirculation of exocrine pancreatic RNase exists in the rat, only negligible quantities of RNase are included in such a recirculation.

Animals↗
PubMed1981

Ulcerative colitis complicated by autoimmune hemolytic anemia.

We have reported the rare association of severe autoimmune hemolytic anemia with active ulcerative colitis, and added to the sparse published recommendations concerning management. Although aggressive medical therapy resulted in only partial control of the inflammatory bowel disease and hemolysis, both disorders remitted rapidly after panproctocolectomy and splenectomy. Autologous red cells were safely transfused during surgery.

Adult↗
PubMed1981

Cell reorganization in vitro of heterosexual gonadal cocultures.

Male and female gonadal cells of newborn rats were cocultured in varying proportions. As low a proportion as 20% of male cells essentially yielded tubular structures. At lower quotas of testicular cells, however, only follicular structures occurred. Mixed structures were not observed except one experiment (20% male cells). When ovarian cells were cocultivated with male nongonadal cells, no conversion occurred. It is assumed that H-Y antigen secreted by male gonadal cells is bound by the ovarian receptor sites and induces conversion into tubular structures. H-Y antigen integrated into the cell membrane of nongonadal male cells does not seem to be able to exert this morphogenetic effect.

Animals↗
PubMed1981

An oocyte-specific antigen and its possible role in the organization of the ovarian follicle of the rat.

An oocyte-specific antigen was detected by an antiserum produced in isogenic Lewis rats. The antigen was sensitive to trypsin treatment. Dissociation-reorganization experiments in vitro, using ovarian cells demonstrated that the antigen is required for the interaction of germ cells and somatic cells. A physiologic role is suggested for this differentiation antigen in follicular morphogenesis and ovarian function.

Animals↗
PubMed1981

Reaggregation of rat gonadal cells in vitro: experiments on the function of H-Y antigen.

Dispersed cells of the gonads of newborn rats reaggregate histotypically in rotation culture. Ovarian cells form follicles, while testicular cells organize tubuli. When testis cell supernatant is added to ovarian cells, they form tubulus-like structures. This effect is impeded by simultaneous addition of monoclonal anti-H-Y antibody. It is concluded that H-Y antigen is the active factor of testis cell supernatant that induces sex-reversal of ovarian cells in vitro. The reverse experiment, i.e., exposure of testicular cells to anti-H-Y antiserum, does not result in the organization of follicular structures. These findings are consistent with the view that H-Y antigen is involved in testis differentiation by inducing testis cell-specific functions, rather than by cross-linking cells.

Animals↗