lonnie empey | UNR - Academia.edu (original) (raw)

Papers by lonnie empey

Research paper thumbnail of Prostaglandins in Inflammatory Bowel Disease Therapy

Canadian Journal of Gastroenterology, 1993

Research paper thumbnail of Vitamin E Prevents Cold Wrap Restraint Stress-Induced Intestinal Fluid Transport Alterations in Rats

Canadian Journal of Gastroenterology, 1994

Psychological stress may alter gastrointestinal absorptive function by increasing the quantity of... more Psychological stress may alter gastrointestinal absorptive function by increasing the quantity of intestinal free radicals or by lowering endogenous intestinal free radical scavenging capacity. Vitamin E has been shown to be a potent endogenous antioxidant and free radical scavenger under both physiological and pathological conditions. The purpose of this study was to determine whether cold wrap restraint stress altered in vivo intestinal fluid absorption in rats, and whether vitamin E administration prior to the induction of cold wrap restraint stress could prevent such changes in intestinal secretion. Jejunal, ileal and colonic fluid and electrolyte transport rates were measured in vivo using an isolated loop technique. Cold wrap restraint stress reduced in vivo fluid absorption in the ileum and colon, but not in the jejunum. Administration of vitamin E prior to the cold wrap restraint stress procedure completely prevented this alteration of ileal and colonic fluid absorption.

Research paper thumbnail of Effect of misoprostol in preventing stress-nduced intestinal fluid secretion in rats

Prostaglandins Leukotrienes and Essential Fatty Acids, 1989

Research paper thumbnail of Effect of misoprostol in preventing stress-induced intestinal fluid secretion in rats

Prostaglandins, Leukotrienes and Essential Fatty Acids, 1989

Research paper thumbnail of Misoprostol provides a colonic mucosal protective effect during acetic acid-induced colitis in rats

Gastroenterology, 1990

This study determined if intracolonically applied prostaglandin E1 analogue (misoprostol) had a m... more This study determined if intracolonically applied prostaglandin E1 analogue (misoprostol) had a mucosal protective effect in rats with 4% acetic acid-induced colitis. The effects of misoprostol were compared with those of 5-aminosalicylic acid and betamethasone. A ...

Research paper thumbnail of Fish oil-enriched diet is mucosal protective against acetic acid-induced colitis in rats

Canadian journal of …, 1991

Products of arachidonic acid metabolism are elevated in patients with inflammatory bowel disease ... more Products of arachidonic acid metabolism are elevated in patients with inflammatory bowel disease and this elevation is correlated with disease activity. Eicosapentaenoic acid competes with arachidonic acid and alters eicosanoid biosynthesis. In this experiment, the possibility that eicosapentaenoic acid could be used in the treatment of inflammatory bowel disease was investigated by determining the effect of 6 weeks of a fish oil-supplemented diet, enriched in eicosapentaenoic acid, on colonic and ileal morphology, histology, and in vivo fluid absorption in rats with 4% acetic acid-induced colitis. The results of an eicosapentaenoic acid-enriched diet were compared with results of saturated and polyunsaturated fatty acid-enriched diets. In rats with misoprostol pretreated acetic acid-induced colitis, an eicosapentaenoic acid-enriched diet reversed net colonic fluid secretion to absorption and prevented macroscopic and histologic injury, compared with saturated and polyunsaturated fatty acid-enriched diets, which did not. The fish oil mucosal protective effect occurred in the presence of a 30-fold enhancement of PGE2 synthesis. In rats with non-misoprostol pretreated acetic acid-induced colitis, an eicosapentaenoic acid-enriched diet returned ileal fluid absorption to control levels, as compared with saturated and polyunsaturated fatty acid-enriched diets, which did not. In conclusion, a fish oil (eicosapentaenoic acid)-enriched diet, but not a saturated-or a polyunsaturated-enriched diet, protected colonic and ileal net fluid absorption in an experimental model of inflammatory bowel disease.Key words: eicosapentaenoic acid, fish oil, colitis, inflammatory bowel disease, leukotrienes, prostaglandins, misoprostol.

Research paper thumbnail of Indomethacin worsens and a leukotriene biosynthesis inhibitor accelerates mucosal healing in rat colitis

Canadian Journal of …, 1992

The implication of leukotrienes as mediators of inflammation and recent evidence that prostagland... more The implication of leukotrienes as mediators of inflammation and recent evidence that prostaglandin analogues provide a beneficial effect during experimental colitis led to the speculation that (i) leukotrienes may be injurious and (ii) prostaglandins may be protective to colonic mucosa. Using a 2% acetic acid induced rat colitis model, we administered specific cyclooxygenase (indomethacin) and leukotriene biosynthesis inhibitors (MK-886) to examine the effect of endogenous prostaglandins and leukotrienes on colonic macroscopic injury, mucosal inflammation as measured by myeloperoxidase activity, net in vivo intestinal fluid absorption, and colonic PGE2 and LTB4 levels as measured by in vivo rectal dialysis. Indomethacin treatment prior to induction of colitis reduced endogenous mucosal PGE2 levels and exacerbated macroscopic ulceration and net fluid absorption. Addition of the exogenous PGE1 analogue misoprostol to the indomethacin-exacerbated colitis completely healed colonic macroscopic ulceration and inflammation but only partially improved fluid absorptive injury. The specific leukotriene biosynthesis inhibitor MK-886 administered prior to induction of colitis healed macroscopic ulceration and inflammation but not fluid absorptive injury. This mucosal reparative effect of MK-886 occurred at a dose that reduced colonic LTB4 synthesis while concomitantly enhancing PGE2 levels. Combining MK-886 with misoprostol treatment improved not only macroscopic ulceration and inflammation but also provided a synergistic effect that maintained net colonic fluid absorption at noncolitic control levels. These studies suggest that, during the induction of experimental colitis, endogenous prostaglandins play a pivotal role in providing a mucosal healing effect, and that leukotriene biosynthesis inhibitor may manifest part of its beneficial effect by shifting arachidonic acid metabolism towards production of prostaglandins.Key words: cyclooxygenase, eicosanoids, indomethacin, inflammatory bowel disease, leukotrienes, lipoxygenase, MK-886, misoprostol, prostaglandins.

Research paper thumbnail of Acetic acid-induced colitis results in bystander ileal injury

Inflammation Research, 1993

Research paper thumbnail of Mucosal protective effects of vitamin E and misoprostol during acute radiation-induced enteritis in rats

Digestive diseases and …, 1992

Cytotoxic effects of ionizing radiation on gastrointestinal epithelium may be mediated by oxygen ... more Cytotoxic effects of ionizing radiation on gastrointestinal epithelium may be mediated by oxygen free radicals. Therapeutic intervention directed toward oxidant scavenging and increasing tissue oxygen tension may provide a novel approach to management. We investigated the effects of a nonenzymatic oxygen radical scavenger (vitamin E) and an exogenous PGE1 analog known to increase mucosal blood flow (misoprostol) on acute radiation enteritis. Rats were pretreated with: (1) vitamin E, (2) misoprostol, or (3) a combination of both agents prior to 10 Gy abdominal radiation. Three days following irradiation, net fluid absorption using in vivo isolated loops, mucosal histology, and mucosal morphometry using a computerized videoplan were determined in jejunum, ileum, and colon. Nonirradiated control intestine demonstrated net fluid absorption in all segments, which was not altered by vitamin E and/or misoprostol treatment. Irradiation significantly reduced net fluid absorption in jejunum, ileum, and colon. Vitamin E administered prior to irradiation maintained jejunal, ileal, and colonic fluid absorption near control levels. In contrast misoprostol or a combination of vitamin E and misoprostol did not provide protection against the injury caused by abdominal irradiation. Alterations in intestinal fluid absorption occurred without significant changes in histologic or morphometric appearance. In conclusion, ionizing radiation reduces in vivo intestinal fluid absorption without significant changes in histologic or morphometric appearance. Treatment with vitamin E, but not misoprostol, protects gastrointestinal mucosa against radiation-induced absorptive injury.

Research paper thumbnail of Misoprostol therapy following trinitrobenzene sulfonic acid-induced colitis accelerates healing

Prostaglandins, Leukotrienes and Essential Fatty Acids, 1992

Prostaglandins have been demonstrated to have a mucosal protective effect when administered prior... more Prostaglandins have been demonstrated to have a mucosal protective effect when administered prior to the experimental induction of colitis in animals. We here determined whether prostaglandins would have a beneficial therapeutic effect when administered after colitis had been established. Diffuse, chronic, trinitrobenzene sulfonic acid-induced colitis was established in rats, and misoprostol was administered daily for up to 10 days following the induction of colitis. The effects of misoprostol therapy were compared to those obtained by treatment with 5-aminosalicylic acid and betamethasone. Misoprostol therapy following trinitrobenzene sulfonic acid-induced colitis accelerated colonic healing, as measured in terms of macroscopic ulceration area and fluid absorption, whereas 5-aminosalicylic acid and betamethasone therapy did not. Ileal fluid absorption impairment was repaired by betamethasone but not by misoprostol or 5-aminosalicylic acid therapy.

Research paper thumbnail of Prostaglandins in Inflammatory Bowel Disease Therapy

Canadian Journal of Gastroenterology, 1993

Research paper thumbnail of Vitamin E Prevents Cold Wrap Restraint Stress-Induced Intestinal Fluid Transport Alterations in Rats

Canadian Journal of Gastroenterology, 1994

Psychological stress may alter gastrointestinal absorptive function by increasing the quantity of... more Psychological stress may alter gastrointestinal absorptive function by increasing the quantity of intestinal free radicals or by lowering endogenous intestinal free radical scavenging capacity. Vitamin E has been shown to be a potent endogenous antioxidant and free radical scavenger under both physiological and pathological conditions. The purpose of this study was to determine whether cold wrap restraint stress altered in vivo intestinal fluid absorption in rats, and whether vitamin E administration prior to the induction of cold wrap restraint stress could prevent such changes in intestinal secretion. Jejunal, ileal and colonic fluid and electrolyte transport rates were measured in vivo using an isolated loop technique. Cold wrap restraint stress reduced in vivo fluid absorption in the ileum and colon, but not in the jejunum. Administration of vitamin E prior to the cold wrap restraint stress procedure completely prevented this alteration of ileal and colonic fluid absorption.

Research paper thumbnail of Effect of misoprostol in preventing stress-nduced intestinal fluid secretion in rats

Prostaglandins Leukotrienes and Essential Fatty Acids, 1989

Research paper thumbnail of Effect of misoprostol in preventing stress-induced intestinal fluid secretion in rats

Prostaglandins, Leukotrienes and Essential Fatty Acids, 1989

Research paper thumbnail of Misoprostol provides a colonic mucosal protective effect during acetic acid-induced colitis in rats

Gastroenterology, 1990

This study determined if intracolonically applied prostaglandin E1 analogue (misoprostol) had a m... more This study determined if intracolonically applied prostaglandin E1 analogue (misoprostol) had a mucosal protective effect in rats with 4% acetic acid-induced colitis. The effects of misoprostol were compared with those of 5-aminosalicylic acid and betamethasone. A ...

Research paper thumbnail of Fish oil-enriched diet is mucosal protective against acetic acid-induced colitis in rats

Canadian journal of …, 1991

Products of arachidonic acid metabolism are elevated in patients with inflammatory bowel disease ... more Products of arachidonic acid metabolism are elevated in patients with inflammatory bowel disease and this elevation is correlated with disease activity. Eicosapentaenoic acid competes with arachidonic acid and alters eicosanoid biosynthesis. In this experiment, the possibility that eicosapentaenoic acid could be used in the treatment of inflammatory bowel disease was investigated by determining the effect of 6 weeks of a fish oil-supplemented diet, enriched in eicosapentaenoic acid, on colonic and ileal morphology, histology, and in vivo fluid absorption in rats with 4% acetic acid-induced colitis. The results of an eicosapentaenoic acid-enriched diet were compared with results of saturated and polyunsaturated fatty acid-enriched diets. In rats with misoprostol pretreated acetic acid-induced colitis, an eicosapentaenoic acid-enriched diet reversed net colonic fluid secretion to absorption and prevented macroscopic and histologic injury, compared with saturated and polyunsaturated fatty acid-enriched diets, which did not. The fish oil mucosal protective effect occurred in the presence of a 30-fold enhancement of PGE2 synthesis. In rats with non-misoprostol pretreated acetic acid-induced colitis, an eicosapentaenoic acid-enriched diet returned ileal fluid absorption to control levels, as compared with saturated and polyunsaturated fatty acid-enriched diets, which did not. In conclusion, a fish oil (eicosapentaenoic acid)-enriched diet, but not a saturated-or a polyunsaturated-enriched diet, protected colonic and ileal net fluid absorption in an experimental model of inflammatory bowel disease.Key words: eicosapentaenoic acid, fish oil, colitis, inflammatory bowel disease, leukotrienes, prostaglandins, misoprostol.

Research paper thumbnail of Indomethacin worsens and a leukotriene biosynthesis inhibitor accelerates mucosal healing in rat colitis

Canadian Journal of …, 1992

The implication of leukotrienes as mediators of inflammation and recent evidence that prostagland... more The implication of leukotrienes as mediators of inflammation and recent evidence that prostaglandin analogues provide a beneficial effect during experimental colitis led to the speculation that (i) leukotrienes may be injurious and (ii) prostaglandins may be protective to colonic mucosa. Using a 2% acetic acid induced rat colitis model, we administered specific cyclooxygenase (indomethacin) and leukotriene biosynthesis inhibitors (MK-886) to examine the effect of endogenous prostaglandins and leukotrienes on colonic macroscopic injury, mucosal inflammation as measured by myeloperoxidase activity, net in vivo intestinal fluid absorption, and colonic PGE2 and LTB4 levels as measured by in vivo rectal dialysis. Indomethacin treatment prior to induction of colitis reduced endogenous mucosal PGE2 levels and exacerbated macroscopic ulceration and net fluid absorption. Addition of the exogenous PGE1 analogue misoprostol to the indomethacin-exacerbated colitis completely healed colonic macroscopic ulceration and inflammation but only partially improved fluid absorptive injury. The specific leukotriene biosynthesis inhibitor MK-886 administered prior to induction of colitis healed macroscopic ulceration and inflammation but not fluid absorptive injury. This mucosal reparative effect of MK-886 occurred at a dose that reduced colonic LTB4 synthesis while concomitantly enhancing PGE2 levels. Combining MK-886 with misoprostol treatment improved not only macroscopic ulceration and inflammation but also provided a synergistic effect that maintained net colonic fluid absorption at noncolitic control levels. These studies suggest that, during the induction of experimental colitis, endogenous prostaglandins play a pivotal role in providing a mucosal healing effect, and that leukotriene biosynthesis inhibitor may manifest part of its beneficial effect by shifting arachidonic acid metabolism towards production of prostaglandins.Key words: cyclooxygenase, eicosanoids, indomethacin, inflammatory bowel disease, leukotrienes, lipoxygenase, MK-886, misoprostol, prostaglandins.

Research paper thumbnail of Acetic acid-induced colitis results in bystander ileal injury

Inflammation Research, 1993

Research paper thumbnail of Mucosal protective effects of vitamin E and misoprostol during acute radiation-induced enteritis in rats

Digestive diseases and …, 1992

Cytotoxic effects of ionizing radiation on gastrointestinal epithelium may be mediated by oxygen ... more Cytotoxic effects of ionizing radiation on gastrointestinal epithelium may be mediated by oxygen free radicals. Therapeutic intervention directed toward oxidant scavenging and increasing tissue oxygen tension may provide a novel approach to management. We investigated the effects of a nonenzymatic oxygen radical scavenger (vitamin E) and an exogenous PGE1 analog known to increase mucosal blood flow (misoprostol) on acute radiation enteritis. Rats were pretreated with: (1) vitamin E, (2) misoprostol, or (3) a combination of both agents prior to 10 Gy abdominal radiation. Three days following irradiation, net fluid absorption using in vivo isolated loops, mucosal histology, and mucosal morphometry using a computerized videoplan were determined in jejunum, ileum, and colon. Nonirradiated control intestine demonstrated net fluid absorption in all segments, which was not altered by vitamin E and/or misoprostol treatment. Irradiation significantly reduced net fluid absorption in jejunum, ileum, and colon. Vitamin E administered prior to irradiation maintained jejunal, ileal, and colonic fluid absorption near control levels. In contrast misoprostol or a combination of vitamin E and misoprostol did not provide protection against the injury caused by abdominal irradiation. Alterations in intestinal fluid absorption occurred without significant changes in histologic or morphometric appearance. In conclusion, ionizing radiation reduces in vivo intestinal fluid absorption without significant changes in histologic or morphometric appearance. Treatment with vitamin E, but not misoprostol, protects gastrointestinal mucosa against radiation-induced absorptive injury.

Research paper thumbnail of Misoprostol therapy following trinitrobenzene sulfonic acid-induced colitis accelerates healing

Prostaglandins, Leukotrienes and Essential Fatty Acids, 1992

Prostaglandins have been demonstrated to have a mucosal protective effect when administered prior... more Prostaglandins have been demonstrated to have a mucosal protective effect when administered prior to the experimental induction of colitis in animals. We here determined whether prostaglandins would have a beneficial therapeutic effect when administered after colitis had been established. Diffuse, chronic, trinitrobenzene sulfonic acid-induced colitis was established in rats, and misoprostol was administered daily for up to 10 days following the induction of colitis. The effects of misoprostol therapy were compared to those obtained by treatment with 5-aminosalicylic acid and betamethasone. Misoprostol therapy following trinitrobenzene sulfonic acid-induced colitis accelerated colonic healing, as measured in terms of macroscopic ulceration area and fluid absorption, whereas 5-aminosalicylic acid and betamethasone therapy did not. Ileal fluid absorption impairment was repaired by betamethasone but not by misoprostol or 5-aminosalicylic acid therapy.