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Biomedical subjects

G M Fraser

Publications and source records attributed to G M Fraser.

At least 55 records · Page 3Linked to original sources
PubMed1993

Hyperplastic polyp and colonic neoplasia. Is there an association?

Hyperplastic polyps are regarded as non-neoplastic lesions with no malignant potential. However, several case reports and a clustering phenomenon suggest that they may arise in abnormal colonic that is predisposed to develop neoplastic lesions. The hyperplastic polyp also displays markers associated with colorectal cancer. In addition, several recent articles have addressed the question of hyperplastic polyp in the distal colon as a marker of more proximal adenomatous polyp. Many endoscopists discovering a distal hyperplastic polyp will wish to ensure the absence of a proximal neoplastic lesion.

Colonic Neoplasms↗
PubMed1992

[Screening for colorectal cancer and polyps].

Screening programs for the early detection of colorectal neoplasms may prevent cancer or improve its prognosis. We screened 1101 individuals (89% of whom were asymptomatic) using 3 methods. The fecal occult blood test, done in 96% of those screened, was positive in only 1.9% and was low in both sensitivity (2.1%) and positive predictive value (6.7%). However, flexible sigmoidoscopy, performed in 48%, gave positive results in 7.8% of those screened, revealing 41 cases of polyps and 1 of cancer. Colonoscopy was performed in 8% and 37 cases of polyps and 1 of cancer were detected. Of the 3 screening methods tested, sigmoidoscopy appeared to be the best because of its high diagnostic yield. The risk of colorectal neoplasm was shown for the first time to be equal in Jews of oriental and occidental origin.

Colonoscopy↗
PubMed1991

Theta, a new class of glutathione transferases purified from rat and man.

Glutathione transferases (GSTs) of a novel class, which it is proposed to term Theta, were purified from rat and human liver. Two, named GST 5-5 and GST 12-12, were obtained from the rat, and one, named GST theta, was from the human. Unlike other mammalian GSTs they lack activity towards 1-chloro-2,4-dinitrobenzene and are not retained by GSH affinity matrices. Only GST 5-5 retains full activity during purification, and its activities towards the substrates 1,2-epoxy-3-(p-nitrophenoxy)propane, p-nitrobenzyl chloride, p-nitrophenethyl bromide, cumene hydroperoxide, dichloromethane and DNA hydroperoxide are 185, 86, 67, 42, 11 and 0.03 mumol/min per mg of protein respectively. Earlier preparations of GST 5-5 or GST E were probably a mixture of GST 5-5 and GST 12-12, which was largely inactive, and may also have been contaminated by less than 1% with another GSH peroxidase of far greater activity. Partial analysis of primary structure shows that subunits 5, 12 and theta are related to each other, particularly at the N-terminus, where 25 of 27 residues are identical, but have little relationship to the Alpha, Mu and Pi classes of mammalian GSTs. They do, however, show some relatedness to subunit I of Drosophila melanogaster [Toung, Hsieh & Tu (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 31-35] and the dichloromethane dehalogenase of Methylobacterium DM4 [La Roche & Leisinger (1990) J. Bacteriol, 172, 164-171].

Amino Acid Sequence↗
PubMed1991

Inflammatory bowel disease in the Bedouin Arabs of southern Israel: rarity of diagnosis and clinical features.

A prospective epidemiological and clinical study of ulcerative colitis and Crohn's disease was undertaken in the Bedouin Arabs of southern Israel between 1981 and 1990. There were six patients with ulcerative colitis and the prevalence rate in 1990 was calculated to be 9.8/10(5) (95% confidence intervals 3.6-17.4) in the total population, or 6.2/10(5) (0.8-22.5) in men and 13.7/10(5) (3.7-35.0) in women. Two cases of Crohn's disease occurred, both in women; the prevalence rate was 3.2/10(5) (0.4-11.8) in the entire population, and 6.8/10(5) (0.8-17.5) in women. The prevalence rates (age adjusted) in Arabs were significantly lower (p less than 0.01) than the corresponding rates in the local Jewish populations. The Bedouin patients were aged mean (SD) 34.0 (16.4) years at time of diagnosis. The clinical features of both diseases resembled those in the Jewish and other reported populations. It is suggested that the exposure of the Bedouin Arabs to the environmental causative factors of ulcerative colitis and Crohn's disease has hitherto been limited and thereby accounts for the rarity of these diseases in this population.

Adolescent↗
PubMed1990

Effect of cimetidine on hepatic vitamin D metabolism in humans.

Cimetidine inhibits the action of vitamin D-hydroxylase (a hepatic mixed-function oxidase) in the rat. Therefore, the hypothesis was tested that this H2 receptor antagonist would affect vitamin D metabolism in humans. Nine adult patients were treated with 400 mg cimetidine orally twice daily during a period from winter to summer, when days were becoming longer. Serum levels of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D and 1,25-dihydroxyvitamin D were monitored before treatment, after 4 weeks of treatment, and 1 month after cessation of treatment. No seasonal increase in the level of 25-hydroxyvitamin D was observed during the period of treatment, but the level rose significantly after withdrawal of the drug. The other hydroxylates of vitamin D were not affected. Levels of albumin, total calcium, phosphorus and alkaline phosphatase remained normal. The data suggest that short-term treatment with cimetidine could potentially perturb vitamin D metabolism in man.

Cimetidine↗
PubMed1988

Modifications to the gas-enhanced small bowel barium follow-through using gastrografin and compression.

The transit time of barium through the small bowel has been assessed in two groups of patients. In 52 patients who were given 300 ml 50% w/v baritop and effervescent tablets, the mean transit time was 78.4 min. In 61 patients who were given 300 ml 100% w/v baritop to which 10 ml of Gastrografin had been added, and who were also given effervescent tablets, the mean transit time was 60.2 min. This difference is highly significant (P less than 0.001). It is suggested that small quantities of Gastrografin act as an accelerator of barium transit by causing the release of serotonin (5-hydroxytryptamine) from the small intestinal mucosa. We believe that the distension of the small bowel lumen achieved by the administration of effervescent tablets improves the quality of the small bowel follow-through examination and also improves its accuracy particularly in the diagnosis of Crohn's disease and small bowel adhesions. The importance of performing the whole examination under fluoroscopic control and the value of compression films is stressed.

Barium Sulfate↗
PubMed1988

Differential distribution of protein kinases along the crypt-to-lumen regions of rat colonic epithelium.

The activity of cAMP-dependent and cAMP-independent protein kinases, a class of enzymes involved in the regulation of cell proliferation was measured in rat colonic epithelium. Sequential cell populations harvested by a stepwise scraping technique from colonic crypt regions were identified by histology and incorporation of [3H]-thymidine into DNA. cAMP-independent phosphorylation of casein, in the presence of [gamma-32P]ATP, was markedly suppressed by quercetin, a bioflavonoid known to inhibit G-type casein kinase, protein kinase-C and tyrosine protein kinase. Conversely, the cyclic nucleotide regulatable form requiring histone as substrate was responsive to the action of the heat stable protein kinase inhibitor. The protein kinase species were characterised and partially purified by DEAE-cellulose chromatography. The activity of cAMP-dependent protein kinase in colonic cytosols (pmol 32P/min/mg protein, means (SE)) increased from 129.4 (15.9) in superficial cell populations to 238.5 (31.4) in lower crypt cell fractions (p less than 0.01). Colonic cAMP-independent protein kinase activity increased from 87.3 (15.6) in surface cell preparations to 178.1 (30.0) in lower crypt cell populations (p less than 0.02). A comparable activity gradient was observed in membrane fractions. The activity gradient persisted when the results were expressed as a function of cellular DNA. These findings indicate that protein kinases display a defined topological segregation along the colonic crypt regions and that during migration to the lumen colonic cells attenuate enzyme signals supposedly related to tissue growth.

Animals↗
PubMed1987

Hepatitis B infections in a chronic hemodialysis unit in a country where hepatitis B is endemic: a prospective study.

Hepatitis B markers were determined in patients with chronic renal failure and in staff members prior to entry into the hemodialysis unit of a hospital in southern Israel, an area in which hepatitis B is endemic. Patients and staff who were negative for hepatitis B markers were followed for a mean of 26.7 and 29.2 months, respectively, between November 1975 and May 1984. New infections occurred in 25.9% of the patients and 17.3% of the staff; the difference was not statistically significant. Hepatitis B markers were found in 26% of the staff and 41% of the patients (p less than 0.05) prior to their entry into the hemodialysis unit. Furthermore, in the patients, a relatively high rate of carriers was detected (7% compared with 2% in the general population), while no carriers were detected among the staff members. Within the staff group, nurses were at particularly high risk for new infections, accounting for seven of the nine (78%) events recorded. The high risk for the nursing staff is probably due to greater exposure to blood among nurses compared with other staff members.

Carrier State↗
PubMed1983

The double-contrast barium meal: a correlation with endoscopy.

The radiological and endoscopic findings are described in 214 patients with 252 lesions in whom endoscopy had been requested by a radiologist either to confirm or clarify a radiological opinion. There was radiological and endoscopic agreement about the presence or absence of oesophagitis in 73% of patients, but there was agreement about the presence or absence of duodenitis in only 48%. There were only two cases of early gastric cancer, and no early gastric cancers were found in a group of 43 patients on whom endoscopy had been specifically requested because of an abnormal gastric mucosal pattern. Endoscopy failed to detect 13% of gastric ulcers at the initial endoscopic examination.

Barium Sulfate↗
PubMed1983

The small bowel barium follow-through enhanced with an oral effervescent agent.

A method is described for consistently improving the quality of the small bowel barium follow-through by enhancement with an oral effervescent agent. With this method, although satisfactory double-contrast views of the whole small bowel were obtained in less than half the patients, satisfactory distension of the small-bowel loops was achieved in 96% of examinations.

Barium Sulfate↗
PubMed1982

Extrinsic compression of the third part of the duodenum.

The clinical findings in 12 patients who exhibited marked to-and-fro peristalsis in the duodenum with extrinsic compression of the third part and proximal dilatation at barium meal examination are described. In nine cases the compression was thought to be due to the superior mesenteric artery and its mesentery. In two of these cases there was associated duodenal ulceration and in another patient there was evidence of chronic idiopathic intestinal pseudo-obstruction. In the remaining three cases, the duodenal compression was caused either by tumour or malignant glands in the root of the mesentery. It is emphasised that vigorous to-and-fro peristalsis in the proximal duodenum seen at fluoroscopy is an abnormal radiological feature which is associated in most cases with significant pathology.

Adolescent↗