Geographical distribution of biomedical publications from the Gulf Corporation Council countries.

OBJECTIVE: It was our purpose to perform a geographical analysis for the number of biomedical and clinical research publications from the six countries of the Gulf Cooperation Council over the past decade (1990-1999). METHODS: Medline was searched with the aid of the Internet provider PubMed. By using the advanced search option, entries were based on the country name for each of the Gulf Cooperation Council countries and the time period considered. RESULTS: The number of Medline-listed biomedical research papers published in the Gulf Cooperation Council countries over the last 10 years totaled 6,960 and increased by 14% over the past decade. The Kingdom of Saudi Arabia followed by Kuwait was by far the most prolific and accounted for 67 and 16% of publications. The research output from the United Arab Emirates and Oman grew steadily over the past decade, while it appeared to plateau for both Bahrain and Qatar. CONCLUSION: Taking into account that Gulf Cooperation Council countries have a relatively short history of research, the data show that the Gulf Cooperation Council countries are very prolific in terms of Medline-indexed biomedical research publications.

Gastric carcinoma in the Sultanate of Oman: Incidence and distribution.

Gastric carcinoma has always been considered a major problem in the Sultanate of Oman. This study was conducted to document the cases in Oman over a two-year period, in order to determine incidence, age, sex and geographical distribution of the condition. All cases of gastric carcinoma in Omani nationals presenting to the medical facilities throughout Oman from November 1987 to November 1989 were reviewed from pathology records, surgical database records and by personal communication with surgeons at regional hospitals. Specimens taken at surgery or endoscopic biopsy were examined and classified according to Lauren's criteria. Over the two-year period, 104 cases of gastric carcinoma were observed. This represented an annual incidence of 4.2/100,000 population, but when adjusted to the standard European population age distribution (in the Oman population, 51% are under 15 years of age), the incidence was 8.6/100,000. The male:female ratio was 1.6:1 and the peak age group was 60-69. All tumors were advanced and most were located in the antral part of the stomach. There were more intestinal types of tumors than diffuse and a preponderance of intestinal metaplasia. This first survey of stomach carcinoma in Oman will provide a reference for future studies and indicates the need for earlier detection.

Weight loss induced by gastric implant in rats. Effects of capsaicin sensory denervation.

To study the efficacy and mechanism of action of the intragastric bubble, 1- to 5-ml silicone bubbles were surgically implanted into the stomachs of 10- to 12-week-old female rats. To test the hypothesis that the satiety effects of the implant are mediated by visceral sensory nerves, a subgroup was treated as neonates with the sensory neurotoxin capsaicin, 50 mg/kg subcutaneously. In control animals, the implants caused a transient decrease in body weight, compared to sham-implanted animals, most evident at three days and abolished by 18 days after operation. In contrast, capsaicin-treated animals did not lose weight in response to gastric implantation. Substance P was decreased in the vagus nerves of capsaicin-treated animals, confirming sensory denervation. At autopsy, all gastric implanted rats had enlarged stomachs. We conclude that intact sensory innervation is essential for weight loss in response to the gastric bubble.

Piroxicam decreases postirradiation colonic neoplasia in the rat.

This study evaluated the effects of the nonsteroidal antiinflammatory agent piroxicam on chronic radiation proctitis in the rat. Forty female Wistar rats received a 2250-cGy dose of irradiation to the distal 2 cm of the colon. Twenty received piroxicam 8.0 mg/kg orally 30 minutes before exposure and 24 hours after exposure; 20 rats served as irradiated controls. All animals were evaluated by colonoscopy 1 and 3 weeks postexposure and every third week until death or killing at 1 year. At killing, colons were removed for light microscopic examination. One year postirradiation results showed no differences in mortality, vascular changes, acute inflammation, colitis cystica profunda, or rectal stricture between the control and piroxicam-treated groups. However, at 1 year postirradiation the control group demonstrated neoplasia in 15 of 19 animals compared with eight of 20 animals in the piroxicam-treated group. The first endoscopic appearance of colonic neoplasm occurred at 15 weeks postirradiation in one control irradiated rat whereas the first evidence of endoscopic neoplasm in the piroxicam-treated group did not occur until 36 weeks postirradiation. Histologic examination documented a tendency toward a greater presence of adenocarcinomas in the control group compared with the piroxicam-treated group. The authors conclude that piroxicam treatment significantly decreased the incidence of colonic neoplasia in general as well as delayed the endoscopic appearance of colonic neoplasia in rats after pelvic irradiation.

Radiation-induced proctitis cystica profunda in the rat.

Therapeutic pelvic irradiation is notorious for the production of clinically significant sequela after a long latency. One of the rarest of these complications is proctitis cystica profunda (PCP). To study the histologic changes of chronic radiation proctitis, we evaluated 35 female Wistar rats that had received a single exposure of 22.5 Gy of radiation to the rectum and were then followed for one year. We identified PCP and its precursor lesions in 18 rats. The fully developed lesion consisted of a focal expansion of the submucosa by dilated cystic spaces lined by a single layer of benign epithelial cells. Usually, PCP evolved as glands herniated between small defects in the muscularis mucosae. Mitotic figures were not recognized in the cells lining the herniating glands. In two rats, the radiation had apparently caused large ulcers, which had subsequently reepithelialized, resulting in prominent submucosal glandular tissue. Although the number of goblet cells in the displaced epithelium was reduced, the cells had rather mature appearances ultrastructurally. Glands displaced into the submucosa were encased by an intact basal lamina but lacked in muscularis.

Effects of a gastric implant on body weight and gastrointestinal hormones in cafeteria diet obese rats.

In order to evaluate the effectiveness of a gastric implant in an animal model of dietary obesity, silicone implants (2.5 ml) were inserted into the stomachs of male rats maintained on a chow or "cafeteria" diet. At the time of implantation, the cafeteria fed rats weighed 14% more than chow fed controls. Overweight cafeteria fed animals lost weight in response to the gastric implant, whereas control chow fed animals did not. Both implant groups had significant increases in stomach weights in contrast to sham implant groups, but the increase was much less in the cafeteria diet group. The fasting plasma levels of the gastrointestinal hormones, gastrin and pancreatic polypeptide, and oxytocin (a marker of vagal afferent function) were measured by radioimmunoassay. Cafeteria fed sham or implanted animals had significantly higher fasting levels of plasma oxytocin and gastrin, and significantly lower plasma levels of pancreatic polypeptide than the chow fed groups. These studies demonstrate that the gastric implant has more effect on weight in overweight animals on a palatable mixed diet, perhaps related to both mechanical and neural factors.

Radiation proctitis in the rat. Sequential changes and effects of anti-inflammatory agents.

Female Wistar rats were treated with single exposure irradiation to 2 cm of distal colon to cause radiation proctitis. All animals were evaluated by examination, colonoscopy and histologic evaluation for changes post-irradiation. Exposures of 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5 and 30 Gy caused dose-related clinical and histologic changes peaking at 7 to 15 days post-exposure. Rats treated with 20 Gy were colonoscoped and biopsied daily and showed sequential post-irradiation endoscopic changes ranging from mucosal edema and mild inflammatory changes to erosion and ulcers. Histologically, crypt abscess and mural wall necrosis similar to changes found in the human rectum after radiotherapy were noted. Treatment with nonsteroidal anti-inflammatory agents, (aspirin, indomethacin, piroxicam), misoprostol (a prostaglandin E1 analogue), or sucralfate (an anti-ulcer agent) did not ameliorate nor exacerbate radiation proctitis in rats exposed to 22.5 Gy. We conclude from these data that the female Wistar rat is a good model for studying radiation proctitis because endoscopic, histologic, and clinical changes seen post-exposure closely resemble those found in man.

Antiinflammatory agents protect opossum esophagus during radiotherapy.

Eighteen opossums received 2250 rad 60Co to the entire esophagus and lower esophageal sphincter. Animals received treatment with 600 mg aspirin, 25 mg/kg hydrocortisone, or saline before irradiation and twice daily for 1 week after irradiation. At 10 days postirradiation, animals were evaluated for signs of acute esophagitis by esophagoscopy and barium esophagram. Each animal was then killed and the esophagus removed and evaluated histologically. Animals treated with either aspirin or hydrocortisone had significantly milder esophagitis than control irradiated animals.

Do prostaglandins cause gastrointestinal mucosal injury?

We have reviewed various examples of the injurious effects of prostaglandins on the gastrointestinal tract along with evidence that, in certain disease states, nonsteroidal antiinflammatory agents may have a prophylactic or therapeutic effect. The most important areas in which these drugs may be useful are in treatment or prevention of esophagitis, food intolerance symptoms, cholera, radiation-induced diarrhea, and ulcerative colitis. Although these two sets of facts appear to be contradictory, they may actually represent two distinct phenomena. The examples of deleterious effects of prostaglandins on gastrointestinal mucosa are all examples of inflammatory changes. Many changes occur in acute inflammation, including leukocytosis and chemotaxis of neutrophils to the area of inflammation. Release of many substances, including prostaglandins, histamine and bradykinin, occurs into the inflamed site. The prostaglandins involved in inflammation of the gastrointestinal mucosa may be quite different in source, type, and quantity from endogenous prostaglandins which play a role in cytoprotection. In addition, because other substances in addition to prostaglandins are involved in inflammation, and nonsteroidal antiinflammatory agents do not act exclusively by inhibition of prostaglandin synthesis, the therapeutic benefit of antiinflammatory agents in gastrointestinal mucosa may be due to several mechanisms. Therefore, in spite of the strong evidence indicting nonsteroidal antiinflammatory drugs as occasionally harmful to the gastric, duodenal, and intestinal mucosa, we should not lose sight of their important potential therapeutic role in other areas of the gastrointestinal tract.

Stimulation of cholinergic nerves in dog intestine by adenine nucleotides.

ATP, ADP, adenosine and AMP, but not adenine, inosine, or GMP, caused dose-related intestinal contractions when injected as intra-arterial bolus doses in vascularly perfused isolated segments of dog small bowel. The stimulatory effects of these agents were decreased by receptor densitization during exposure to high concentrations of ATP. ATP-induced contractions were also decreased by tetrodotoxin or atropine and after depletion of neuroinal acetylcholine content by hemicholinium. Depolarizing doses of nicotine blocked responses to ATP, but nicotinic receptor blockade with tetraethylammonium did not. It is concluded that ATP stimulates dog intestine by release of endogenous acetylcholine from intramural neural elements as a result of actions upon non-nicotinic receptors.

Radiation esophagitis in the opossum: radioprotection with indomethacin.

Twenty-five opossums (Didelphis virginiana) were evaluated before irradiation by fiberoptic endoscopy and air-contrast barium esophagram examination. All animals received 2250 rad 60Co-irradiation in a single exposure to the entire esophagus and lower exophageal sphincter. Animals received treatment with indomethacin before and daily for 1 wk postirradiation of 16, 16-dimethylprostaglandin E2 before irradiation and every 4 hr for 24 hr postirradiation. Control animals received only injection vehicle. Acute esophagitis occurred 7--10 days postirradiation in control animals and was characterized by erythema, ulceration, and sloughing of esophageal mucosa as determined by air-contrast barium esophagram, endoscopy, and histology. Prostaglandin-treated animals showed more severe evidence of esophagitis than control animals. Indomethacin-treated animals showed no signs or only mild esophagitis posttreatment. It is concluded that indomethacin treatment may significantly reduce the severity of radiation esophagitis perhaps by blockade of prostaglandin synthesis.

Indirect intestinal stimulatory effects of heroin: direct action on opiate receptors.

The effects of bolus intra-arterial doses of heroin and other stimulant drugs were studied in vascularly perfused isolated segments of dog small intestine. Heroin caused dose-related increases in intraluminal pressure similar in appearance to those caused by morphine. Perfusion with Krebs bicarbonate solution containing naloxone selectively abolished intestinal responses to heroin. Perfusion with cinanserin, a 5-hydroxytryptamine (5-HT) antagonist, decreased intestinal responses to 5-HT and heroin without affecting responses to dimethylphenylpiperazinium (DMPP) or bethanechol (BeCh). Tetrodotoxin reduced responses to heroin, 5-HT and DMPP but not responses to BeCh. Atropine antagonized contractile responses to all 4 stimulatory agents. These data indicate that heroin interacts with a conventional opiate receptor in the intestine and that the intestinal stimulatory effect of heroin is mediated by the release of endogenous 5-HT which activates intramural cholinergic neurons.

A technique for barium esophagram in the opossum.

Single and double contrast barium esophagram examinations were performed on 42 opossums. Each animal was anesthetized with pentabarbital sodium, a catheter was placed in the esophagus, and barium or barium and air were injected into the esophagus. Two radiographs per second for 7 seconds were taken. The radiographs were reproducible and of high quality.

The opossum as an animal model for studying radiation esophagitis.

Six opossums were evaluated as a possible animal model of radiation esophagitis. In a single exposure to the esophagus, four animals received 60Co radiation of various doses; two served as controls. Pre- and postirradiation evaluations using fiberoptic endoscopy, mucosal biopsy, barium esophagography, and manometry were performed. Esophagitis developed at one week in irradiated animals. Opossums receiving 17.5, 20, and 22.5 Gy (1,750; 2,000; and 2,250 rad) became anorexic one week postirradiation, and abnormal motility subsequently developed. The controls and the animal receiving 15 Gy (1,500 rad) remained normal. Histological changes in the irradiated opossum esophagus resembled those found in humans.