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Biomedical subjects

M H Thompson

Publications and source records attributed to M H Thompson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Annular pancreas and obstructive jaundice.

Annular pancreas is a rare abnormality which, in some cases, will be an incidental finding. Recently, two case reports have highlighted the possibility that annular pancreas is responsible for extrahepatic biliary obstruction in the absence of pancreatitis. We present a case of obstructive jaundice in which an annular pancreas was noted at both ERCP and CT scanning, but in which the cause of the obstruction was a carcinoma of the ampulla of Vater. Obstructive jaundice should not be attributed to an annular pancreas until the alternative differential diagnoses have been positively excluded.

Adenocarcinoma↗
PubMed1996

Ethics committees: their share in the advocacy role.

In the wake of escalating health care costs and advances in technology, health care faces an ever-increasing number of ethical dilemmas. Never before has the need for advocacy been greater, and never before has the role of ethics committees as advocates for patients and families been as imperative.

Aged↗
PubMed1995

Hypermutability of mouse chromosome 2 during the development of x-ray-induced murine myeloid leukemia.

In an effort to identify the precise role of a deletion at regions D-E of mouse chromosome 2 [del2(D-E)] during the development of radiation-induced myeloid leukemia, we conducted a serial sacrifice study in which metaphase chromosomes were examined by the G-banding technique. Such metaphase cells were collected from x-irradiated mice during the period of transformation of some of the normal hematopoietic cells to the fully developed leukemic phenotype. A group of 250 CBA/Ca male mice (10-12 weeks old) were exposed to a single dose of 2 Gy of 250-kilovolt-peak x-rays; 42 age-matched male mice served as controls. Groups of randomly selected mice were sacrificed at 20 hr, 1 week, and then at intervals of 3 months up to 24 months after x-irradiation. Slides for cytogenetic, hematological, and histological examination were prepared for each animal at each sacrifice time. An expansion of cells with lesions on one copy of chromosome 2 was evident in 20-25% of treated mice at each sacrifice time. The majority of such lesions were translocations at 2F or 2H, strongly suggesting hypermutability of these sites on mouse chromosome 2. No lesions were found in control mice. The finding leads to the possibility that genomic lesions close to 2D and 2E are aberrants associated with radiation leukemogenesis, whereas a single clone of cells with a del2(D-E) may lead directly to overt leukemia. The data also indicate that leukemic transformation arises from the cumulative effects of multiple genetic events on chromosome 2, reinforcing the thesis that multiple steps of mutation occur in the pathogenesis of cancer.

Animals↗
PubMed1995

Prospective evaluation of ultrasonography and liver function tests for preoperative assessment of the bile duct.

Current means of predicting the presence of bile duct stones are sensitive but produce a large number of false-positive results, potentially leading to added morbidity from unnecessary invasive investigation. This study prospectively assessed 545 patients with gallbladder stones, including 55 patients with bile duct stones, to refine criteria for further investigation of the bile duct. The sensitivity, specificity, and positive and negative predictive values were calculated for bile duct dilatation (diameter abnormal if larger than 5 mm below age 50 years, normal value increasing by 1 mm per decade) and elevation of three liver function tests, singly or in combination. Depending on the number of abnormalities used the sensitivity ranged from 46 to 96 per cent and the positive predictive value from 35 to 77 per cent. All groupings gave at least 96 per cent negative predictive value for the absence of stones but none combined both high sensitivity and positive predictive value. The specificity was improved if the tests were done on the working day before operation. Refining criteria for predicting bile duct stones allows the selective use of cholangiography and may reduce the number of negative cholangiograms.

Adolescent↗
PubMed1995

Infection after laparoscopic cholecystectomy: are antibiotics really necessary?

OBJECTIVE: To establish the incidence of infection after laparoscopic cholecystectomy, and assess the need for antibiotic prophylaxis. DESIGN: Prospective open study. SETTING: University teaching hospital, United Kingdom. SUBJECTS: 253 consecutive patients undergoing laparoscopic cholecystectomy between September 1990 and January 1993. INTERVENTIONS: A single intravenous dose of cefuroxime 1.5 g at induction of general anaesthesia. MAIN OUTCOME MEASURES: Infective complications. RESULTS: Patients were reviewed at two weeks and 12 months. At two weeks there had been two wound infections (one resolved spontaneously and the other required removal of a gallstone from the subcutaneous tissue), two chest infections (treated with antibiotics orally and physiotherapy), and one subhepatic abscess (drained percutaneously under ultrasonographic control). No other complications were reported at 12 months. CONCLUSIONS: Routine antibiotic prophylaxis may be unnecessary during elective laparoscopic cholecystectomy, but a randomised controlled trial is necessary to confirm this.

Adolescent↗
PubMed1994

Assessment of the common bile duct before cholecystectomy using ultrasound and biochemical measurements: validation based on follow-up.

The selective use of operative cholangiography with cholecystectomy is controversial. We have combined measurement of the serum bilirubin, alkaline phosphatase and alanine aminotransferase with ultrasound measurement of the bile duct diameter to assess the common bile duct before cholecystectomy. Direct contrast cholangiography was not performed if the results of these measurements were normal on the day before operation. There were 253 patients assessed in this way before laparoscopic cholecystectomy. Patients with known bile duct stones were excluded, but those with a previous history of jaundice, pancreatitis or abnormal liver function tests were included. In 47 cases abnormalities were found and X-ray cholangiograms were performed; only six patients were found to have bile duct stones. Follow-up of all 253 patients, including repeating the preoperative measurements after 12 months in 93, found only two patients with evidence that common duct stones had been missed and these two stones passed spontaneously. No bile duct injuries have occurred. We conclude that preoperative assessment of the bile duct using ultrasound and liver function tests safely obviates the need for 'routine' operative cholangiography.

Adolescent↗
PubMed1993

Colonoscopic follow-up after resection for colorectal cancer: a selective policy.

A policy of selective colonoscopy after resection for colorectal cancer was evaluated to assess the benefit of detecting missed synchronous and metachronous tumours in patients under 70 years of age with a good prognosis, and the possible risk of missing such lesions in those not screened. With preoperative barium enema and palpation at laparotomy, synchronous cancers and adenomas were found in 2 and 28 per cent, respectively, of 275 consecutive patients undergoing resection. Eighty-five patients were selected for postoperative colonoscopy, which was repeated at least once in 32, there being a total of 60 repeat examinations. Adenomas, but no cancers, were found in 19 patients (22 per cent) on first screening, but on repeat colonoscopy early metachronous cancers were detected in three patients (9 per cent) and adenomas on 21 examinations (35 per cent). Only one of the patients followed by clinical examination developed a symptomatic tumour. This suggests that postoperative colonoscopy is unlikely to benefit the majority but may be extremely important for young fit patients with continuing polyp formation who are at high risk of developing metachronous cancer.

Adult↗
PubMed1993

A specific chromosomal deletion in murine leukemic cells induced by radiation with different qualities.

G-banded metaphase chromosomes prepared from 14 male CBA/Ca mice with histologically confirmed myeloid leukemia (ML) were studied in an effort to identify specific chromosomal changes associated with radiation leukemogenesis. The chromosome studies were undertaken as part of a larger investigation of radiation carcinogenesis, in which mice were exposed to radiation of several different qualities, i.e., x-rays, gamma-rays and "monoenergetic" fast neutrons of 5 mean energies ranging from 0.2 to 14 MeV. The 14 ML cases showed no histologically phenotypic differences and they were transplantable in syngeneic mice. We detected a specific chromosomal deletion in 1 copy of mouse chromosome 2 at regions D-E in all radiation-induced ML cells, regardless of radiation quality. Our results strongly implicate the involvement of genes within or close to regions D-E of chromosome 2 in radiation leukemogenesis. In addition to the specific deletion in chromosome 2, loss or gain of the Y chromosome was also detected in some cells from 6 ML cases. Because this hypo- or hyperploidy occurred in only a small fraction of leukemic cells, a causative role in radiation leukemogenesis appears unlikely.

Animals↗
PubMed1992

Faecal steroids and colorectal cancer: steroid profiles in subjects with adenomatous polyps of the large bowel.

In this necroscopy study the relation between carriage and size of colorectal polyps was correlated with luminal steroid concentrations in respect to malignant risk. Of the 92 subjects entered into the study, 68 had adenomatous polyps of the large bowel, of which 19 had adenomas > 0.9 cm in diameter (large adenomas), 26 in the range 0.5-0.9 cm in diameter (medium adenomas) and 23 of 0.4 cm or less in diameter (small adenomas). Sixty-three percent of subjects carrying large adenomas and 26% of persons carrying small adenomas had an abnormal ratio (> 1.0) of lithocholic acid to deoxycholic acid in intestinal contents as compared to 17% of the adenoma-free comparison group (n = 24). These findings support the suggestion that the ratio of lithocholic acid to deoxycholic acid as a faecal marker may be a useful adjunct to screening procedures for colorectal cancer.

Adenoma↗
PubMed1992

Six hundred patients with gallstones.

A total of 610 patients with gallstones were treated over an 8-year period in a single surgical unit. Of these patients, 384 had cholecystectomy, 86 surgical duct exploration and 140 endoscopic sphincterotomy. Four patients died after cholecystectomy (1%), but there were no deaths after the treatment of duct stones. The proportion of patients with duct stones having endoscopic sphincterotomy with the gallbladder in situ rose considerably during the 8-year period, from about 20% to 75%. Gallstones tend to present in the elderly as duct stones, and in the young as gallbladder stones. The majority of patients over 75 years of age had endoscopic sphincterotomy, whereas the younger patients were usually treated surgically.

Age Factors↗
PubMed1991

Inhibition of bacterially mediated N-nitrosation by ascorbate: therapeutic and mechanistic considerations.

Ascorbate is known to inhibit the acid-catalysed N-nitrosation reactions of nitrite in the normally acid stomach, suggesting a useful therapeutic application of this compound to reduce exposure to the carcinogenic products of such reactions. However, in the achlorhydric stomach, which is particularly predisposed to cancer, increased exposure to endogenous N-nitroso compounds may result from bacterially catalysed reactions. The mechanism of these bacterially mediated reactions is only just beginning to be understood, and, indeed, more than one such mechanism may exist. Despite its usual lack of reactivity towards nitrite at neutral pH, ascorbate proved to be a potent inhibitor of the bacterially mediated (Pseudomonas aeruginosa) nitrosation of morpholine, competing with morpholine for the nitrosating agent elaborated by the bacteria from nitrite (the kinetics of the inhibition were classically competitive). This and other data, particularly with regard to the dependence of the bacterially mediated reaction on amine pKa, are discussed in relation to the potential mechanisms of these bacterially mediated reactions.

Ascorbic Acid↗