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Biomedical subjects

I C Talbot

Publications and source records attributed to I C Talbot.

At least 19 recordsLinked to original sources
PubMed1992

GB (guanidinobenzoatase) cell surface protease and serum inhibitors in colorectal neoplasia.

Cell surface proteases and their inhibitors are functionally related to the invasive properties and metastatic potential of tumour cells. Epithelial cells of the colorectal mucosa possess a cell surface protease referred to as guanidinobenzoatase (GB), which is similar, if not identical, to plasminogen activator. GB exists in isoenzymatic forms, one of which is associated with epithelial cells of normal colorectal mucosa and of adenomatous polyps, whilst another isoenzymatic form is associated with colorectal adenocarcinoma cells. Normal serum contains inhibitor proteins which recognize the isoenzymatic form of GB found on normal and adenomatous polyp epithelial cells but this inhibitor does not recognize the isoenzymatic form of GB associated with adenocarcinoma cells. The fluorescent probe 9-amino-acridine locates cells possessing active GB in frozen sections of colorectal mucosa. A technique is described which enables colorectal carcinoma cells to be highlighted by fluorescence microscopy whilst normal epithelial cells are distinguished by their lack of fluorescence. This is of biological and possibly diagnostic significance.

Adenocarcinoma↗
PubMed1992

Lafora disease: a progressive myoclonus epilepsy.

Lafora disease is a rare inborn error of metabolism resulting in storage of a polyglucosan in tissues including the brain, skin and liver. Four children are described with progressive myoclonus epilepsy and intellectual deterioration in whom this diagnosis was made. In two the diagnosis was confirmed by the presence of periodic acid schiff (PAS) positive, diastase resistant, colloidal iron staining inclusion material in the liver when they were referred to a paediatric gastroenterologist with abnormal liver function tests. In one, the diagnosis was made from cerebellar biopsy, although on retrospective review the liver biopsy performed at this time was abnormal. In a fourth child, whose sibling was affected, histological diagnosis was confirmed by skin biopsy, although clinical and EEG findings had been highly suggestive for several years. The disease has autosomal recessive inheritance, is progressive and the prognosis is poor. Paediatricians should be aware of this diagnosis, which is often delayed, as early histological diagnosis allows prognostic and genetic counselling and optimal treatment. Although the diagnosis was made by liver or brain biopsy in three cases, skin biopsy offers a reliable, less invasive means of diagnosis.

Adolescent↗
PubMed1992

Double blind, controlled trial of 4-aminosalicylic acid and prednisolone enemas in distal ulcerative colitis.

Corticosteroid or 5-aminosalicylic acid enemas are the treatment of choice for distal ulcerative colitis but up to one third of patients may be unresponsive. As an alternative therapy might be advantageous, the efficacy of six weeks' treatment with 2 g 4-aminosalicylic acid (4-ASA) (n = 24) and 20 mg prednisolone enemas (n = 21) were compared in a double blind, randomised trial in patients with acute distal (less than 30 cm from the anus) ulcerative colitis. Baseline demography and clinical severity were similar in both groups. Five of 24 patients receiving 4-ASA and 4 of 21 receiving prednisolone did not complete the trial because of deteriorating symptoms, failure to improve, or side effects. At the time of leaving the trial, 24 hour stool frequency, the presence of blood in the stools, and histological and sigmoidoscopic appearances were similar in both groups. Symptomatic improvement occurred in 17 of 24 patients receiving 4-ASA compared with 11 of 21 receiving prednisolone (chi 2 = 1.62, NS). Complete symptomatic improvement occurred in 9 of 24 patients receiving 4-ASA compared with 5 of 21 receiving prednisolone (chi 2 = 0.98, NS). Histological improvement was seen in 9 of 24 patients on 4-ASA compared with 7 of 21 on prednisolone (chi 2 = 0.08, NS). One patient receiving 4-ASA was considered to have an idiosyncratic reaction to the drug but other side effects were not considered to be drug related. Thus, 4-ASA, previously used in the treatment of tuberculosis (para-aminosalicyclic acid), is as good as prednisolone in the treatment of distal ulcerative colitis and should be considered in patients unresponsive to steroids or in whom steroid treatment is undesirable.

Aminosalicylic Acid↗
PubMed1992

Dietary and erythrocyte fatty acids in experimental colorectal carcinogenesis.

The influence of dietary fat on the erythrocyte stearic:oleic acid ratio was investigated in an experimental model of colorectal cancer. One hundred male Wistar rats were divided into four separate dietary groups: A (5% saturated fat), B (20% saturated fat), C (5% n-6 unsaturated fat) or D (20% n-6 unsaturated fat). Colorectal tumours were induced by intraperitoneal injection of azoxymethane (n = 60) and control animals received saline (n = 40). Animals were killed after 26 weeks and erythrocyte fatty acid profiles were determined by gas liquid chromatography. Although there were no differences in the incidence of adenoma formation in the four dietary groups, there was a significantly lower incidence of carcinomas in rats fed a 5% or 20% unsaturated fat diet when compared with either a 5% (P less than 0.05) or a 20% saturated fat diet (P less than 0.01). Multivariate analysis of fatty acid profiles demonstrated that both the type and quantity of dietary fat had a highly significant influence on the fatty acid profile of erythrocytes. The stearic:oleic acid ratio varied considerably between the four dietary groups but was only significantly lower in tumour bearing animals compared with controls in group B (20% saturated fat diet).

Animals↗
PubMed1991

Restriction enzyme analysis of mitochondrial DNA in colorectal tumours.

Total cellular DNA samples were isolated from 15 colorectal adenocarcinomas, 8 colon adenomas and their adjacent histologically normal colon mucosa. These DNA samples were digested separately with 13 different restriction endonucleases and analysed by Southern blot hybridization using a purified 32P-labelled human mtDNA probe. The fragment patterns from tumour mtDNA were compared to those from corresponding normal mtDNA. No evidence for large deletions, insertions, rearrangements or single base mutations in the detectable regions was detected. This suggests that other mechanisms may be responsible for the changes of colorectal tumour mitochondria.

Adenocarcinoma↗
PubMed1991

Increased cell membrane arachidonic acid in experimental colorectal tumours.

Tumour cell membrane fatty acid composition was investigated using an animal model of colorectal carcinogenesis. Eighty six male Wistar rats were fed experimental diets containing either 5% saturated fat or 20% saturated fat. Colorectal tumours were induced by intraperitoneal injection of azoxymethane, and control rats received saline. Animals were killed at intervals up to 26 weeks after the last injection of carcinogen for histology and lipid analysis. Cell membrane fatty acids in colonic mucosa and colorectal tumours were determined by gas liquid chromatography. Animals fed the 20% fat diet developed more carcinomas (28 cancers in 14 rats) than those fed the 5% fat diet (14 cancers in 15 rats; chi 2 = 8.03, p = 0.0046) but they did not develop significantly more adenomas (28 and 24 respectively). Cell membrane fatty acid analysis showed a considerable increase in the content of arachidonic acid (20:4, n-6) in the tumours (mean (SEM) 11.7 (1.5)%) compared with colonic mucosa (4.2 (0.4)%; p less than 0.05). Dietary fatty acid composition was also found to influence the profile of fatty acids in the colonic mucosa. This study suggests that a high saturated fat diet promotes the malignant transformation of colorectal adenomas. The colorectal tumours were characterised by an increased cell membrane arachidonic acid, the precursor of putative cancer promoting prostaglandins.

Animals↗
PubMed1991

Malignant colorectal polyps: venous invasion and successful treatment by endoscopic polypectomy.

We reviewed the pathology of 81 malignant colorectal polyps in 80 patients treated by endoscopic polypectomy and assessed the importance of carcinomatous invasion of veins in the stalk (submucosa). All the patients were followed up for at least five years. Venous invasion was present in 30 of the polyps (37%). The histological features of lymphatic invasion were considered too subjective to be of value. Most of the tumours were well or moderately differentiated adenocarcinomas, one was poorly differentiated, and one was a signet ring cell carcinoma. Seventy one patients were treated by polypectomy alone, and 58 of these were alive and well five years later, with no evidence of recurrence. Nine died of unrelated causes within five years, but four died of carcinomatosis: one with recurrent tumour, one with a possible metachronous caecal cancer, and in two patients there was late development of malignancy of uncertain nature. The remaining nine patients underwent surgical resection after initial endoscopic polypectomy because of incompleteness of excision, poor differentiation of the tumour, or a decision by the surgeon. Tumour was not present in the resection specimens apart from a single lymph node deposit in the patient with signet ring cell carcinoma. These nine patients were alive and well without evidence of recurrence five years later. The results reemphasize the necessity of good cooperation between endoscopist and pathologist, meticulous laboratory technique, strict histopathological criteria including examination of resection margins and degree of differentiation of the tumour, and regular endoscopic follow up. Endoscopic polypectomy of pedunculated and sessile malignant polyps is adequate treatment if the lesion can be removed in one piece, the tumour is well or moderately differentiated, and local excision is judged complete by endoscopic and histological criteria. Patients with histologically incompletely excised polyps, containing well or moderately differentiated carcinoma, can be safely managed by conservative treatment provided the endoscopist is certain there is no residual tumour. Venous invasion by tumour is a common finding in malignant colorectal polyps and seems to have no prognostic importance.

Adult↗
PubMed1991

Diversion colitis: histological features in the colon and rectum after defunctioning colostomy.

Diversion of the faecal stream by ileostomy or colostomy leads to inflammation in the defunctioned segment, known as diversion colitis. The affected bowel is rapidly restored to normality by reanastomosis. Diversion colitis should not be mistaken for inflammatory bowel disease, for which reanastomosis would be inappropriate. Studies of biopsy material from patients with diversion colitis have shown a variety of histological features, but no consistent pattern. The histology in resection specimens of defunctioned large bowel from 15 patients with no pre-existing inflammatory bowel disease was studied. Nine patients had symptoms of abdominal pain or rectal discharge of blood or mucus that developed between 9 months and 17 years after diversion procedure. The histology was abnormal in all. Findings were similar in 14 patients, regardless of the duration of faecal diversion, and comprised diffuse mild chronic inflammation with or without mild crypt architectural abnormalities, crypt abscesses, or follicular lymphoid hyperplasia. One patient had more severe changes, resembling active ulcerative colitis. These features in biopsy specimens are unlikely to be diagnostic but should provide useful information in avoiding a mistaken diagnosis of inflammatory bowel disease in these patients.

Adolescent↗
PubMed1991

The Peutz-Jeghers syndrome. Case reports.

Two additional cases of Peutz-Jeghers syndrome are described. One of them, a 19 year-old female, is a sporadic case, whereas in the other case, also a 19 year-old female, there are two members of the family with the Peutz-Jeghers syndrome. A review of some salient features of this entity is made. These include clinical presentation, histopathological features, malignant potential and treatment.

Adult↗
PubMed1990

Incidence of dysplasia in the anorectal mucosa in patients having restorative proctocolectomy.

The incidence of dysplasia in the mucosal strippings from the anorectal stump was studied in 132 patients treated by restorative proctocolectomy with ileal reservoir for ulcerative colitis and familial adenomatosis. The anorectal mucosa was stripped from the level of division of the gut tube to the dentate line. Of 118 patients with ulcerative colitis, 12 (10.2 per cent) had dysplasia in some part of the large bowel. Mucosal strippings were examined histologically in 118 cases, of which only three (2.5 per cent) showed dysplasia. There was a correlation between dysplasia and the presence of carcinoma and the duration of the disease in the operative specimen of colon and rectum and also in the anorectal mucosal specimen although the number of patients with carcinoma (eight cases) in this analysis was small. All 14 patients with familial adenomatous polyposis showed large bowel mucosal dysplasia in the operative specimen which was severe in six cases. Anorectal mucosal strippings were examined in these patients and 12 showed dysplasia which was severe in three.

Adenomatous Polyposis Coli↗
PubMed1990

In situ and slot hybridization analysis of RNA in colorectal tumours and normal colon shows distinct distributions of mitochondrial sequences.

cDNA clones of mRNAs with an abnormal abundance in familial adenomatous polyposis were used to examine the levels and distribution of the mRNAs in tissues from 15 patients with colorectal cancer. Of 12 cloned sequences studied by slot hybridization, one was substantially reduced in tumours compared with normal tissue. Sequence analysis showed this to code for IgA. In situ hybridization was consistent with slot hybridization and immunohistochemistry. Two mitochondrially encoded sequences had distinct distributions detected by in situ hybridization but did not have detectable quantitative differences in whole tumour or mucosa extracts.

Adenocarcinoma↗
PubMed1990

Ultrastructural immunocytochemistry of the intact tissue cyst of Toxoplasma in the brains of mice with congenital toxoplasmosis.

Electron immunocytochemistry, using rabbit polyclonal anti-Toxoplasma IgG as the primary layer in immunogold staining, was used to assess the distribution of Toxoplasma antigen within, and in relation to, intact tissue cysts in brain tissue from mice with congenital toxoplasmosis. Toxoplasma antigen was widely distributed in the matrix of the cyst, being most concentrated in the proximity of the inner surface of the parasitophorous vacuole membrane (PVM). Relatively little Toxoplasma antigen was detected directly associated with cystozoites. Small amounts of antigen were detected within the host cell components exterior to the PVM and in the host neuropil immediately adjacent to the tissue cyst.

Animals↗