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Biomedical subjects

C G Clark

Publications and source records attributed to C G Clark.

At least 109 records · Page 6Linked to original sources
PubMed1985

Post-gastrectomy nutrition: methods of outpatient screening for early osteomalacia.

A cohort of 227 patients treated by partial gastrectomy between 1955-1960 has been followed up regularly for evidence of osteomalacia. Of these, 10 developed clinical or subclinical osteomalacia as proven by bone biopsy. The diagnosis of early asymptomatic osteomalacia in bone biopsies presented many difficulties. As an alternative, patients with a rising serum alkaline phosphatase (SAP) were screened for liver disease, Paget's disease, osteoporotic crush fractures and bony secondaries. In the absence of these a therapeutic trial of eight Calcium and Vitamin D tablets BPC daily was given. In 5 out of 11 patients the SAP fell to normal and these were given a maintenance daily dose of six tablets. These patients were presumed to have had subclinical osteomalacia. This approach, involving regular monitoring of the SAP, is recommended as the most applicable for routine screening of a gastrectomy population, particularly in District Hospitals.

Alkaline Phosphatase↗
PubMed1984

Xenopus laevis 28S ribosomal RNA: a secondary structure model and its evolutionary and functional implications.

Based upon the three experimentally derived models of E. coli 23S rRNA (1-3) and the partial model for yeast 26S rRNA (4), which was deduced by homology to E. coli, we derived a secondary structure model for Xenopus laevis 28S rRNA. This is the first complete model presented for eukaryotic 28S rRNA. Compensatory base changes support the general validity of our model and offer help to resolve which of the three E. coli models is correct in regions where they are different from one another. Eukaryotic rDNA is longer than prokaryotic rDNA by virtue of introns, expansion segments and transcribed spacers, all of which are discussed relative to our secondary structure model. Comments are made on the evolutionary origins of these three categories and the processing fates of their transcripts. Functionally important sites on our 28S rRNA secondary structure model are suggested by analogy for ribosomal protein binding, the GTPase center, the peptidyl transferase center, and for rRNA interaction with tRNA and 5S RNA. We discuss how RNA-RNA interactions may play a vital role in translocation.

Animals↗
PubMed1984

Is colonoscopy necessary in diverticular disease?

Colonoscopy was carried out in 65 patients in whom double-contrast barium enemas for bowel symptoms had shown sigmoid diverticular disease. In 19 of these, barium enemas had shown neoplastic lesions--polyps in 17 and carcinoma in 2; but colonoscopy showed no polyps in 9 of the 17. In 1 a carcinoma not a polyp was found, and of the 2 carcinomas only 1 was confirmed. In 46 patients the barium enemas showed diverticular disease only, but colonoscopy revealed polyps in 8 and carcinoma in 3. Thus in 23 patients (35%) the barium enema was inaccurate. 13 of 20 patients with neoplasia but only 11 of 45 without had rectal bleeding, but the numbers in the two groups who had abdominal pain or change in bowel habit were similar in the two groups. Colonoscopy revealed neoplastic lesions in 20 of the 65 patients (31%), an incidence great enough to recommend routine colonoscopy in patients with symptomatic diverticular disease, especially those with rectal bleeding.

Aged↗
PubMed1984

Laser recanalization of obstructing foregut cancer.

Palliative treatment of upper gastrointestinal tract obstruction was undertaken by endoscopic laser therapy in 6 patients with carcinoma of the oesophagus or stomach. All had dysphagia for solids on admission and were considered unsuitable for surgery or radiotherapy. Three were in sites unsuitable for placement of an endoscopic prosthesis. The tumours occluded up to 90 per cent of the lumen (2 squamous and 4 adenocarcinomas). Treatment was carried out under direct vision, the laser wave guide being passed through the biopsy channel of a standard endoscope. Superficial tumour vaporized immediately using energies of 2-10 000 J per session, whereas deeper layers sloughed over the succeeding 2-3 days. Two to six treatments were required to relieve dysphagia and there were no major complications. Quantitative barium studies before and after treatment showed a significant increase in luminal diameter. These patients could eat solid food after treatment and all were able to go home.

Adenocarcinoma↗
PubMed1984

Preference for proximal gastric vagotomy combined with cholecystectomy.

The incidence and severity of postvagotomy diarrhoea has been studied in 32 patients who had undergone both vagotomy and cholecystectomy. Sixteen of these patients had had a proximal gastric vagotomy and 16 a truncal vagotomy and pyloroplasty. Diarrhoea was present in 68 per cent of patients in whom the vagotomy was truncal and in 31 per cent of those in whom it was proximal gastric. Matched groups of patients with truncal vagotomy with pyloroplasty and proximal gastric vagotomy without cholecystectomy were also compared. The possible mechanisms of this diarrhoea following combined vagotomy and cholecystectomy have been discussed.

Adult↗
PubMed1984

Is chronic detergent ingestion harmful to the gut?

Synthetic detergents are used in large quantities as household and industrial cleaners. Because of the common practice of leaving dishes washed in detergent solutions to dry without rinsing these compounds are ingested. We have calculated that an adult takes in about 1 mg/kg detergent a day and babies can be administered between seven and 10 mg/kg a day. Rats were fed a dose of 100 mg/kg a day in a pilot experiment and gross abnormalities were found in the gastrointestinal tract, the most striking being subtotal villous atrophy of the small bowel mucosa and glandular atrophy in the colon. These changes were not reversible 12 weeks after cessation of detergent administration.

Animals↗
PubMed1984

An investigation into the mechanism of co-carcinogenesis of dietary cholesterol during the induction of colon cancer in rats by 1,2 dimethylhydrazine.

The mechanism by which dietary cholesterol facilities colon carcinogenesis was investigated in the dimethylhydrazine-induced rat colon cancer model. Fifty female Wistar rats received a standard course of dimethylhydrazine (DMH) injections (40 mg/kg/week subcutaneously for ten weeks) while being fed Vivonex, a cholesterol-free elemental diet. Animals were allocated to one of five dietary regimens. One control group received Vivonex with added cholesterol (10 mg/100 ml Vivonex/rat/day) throughout the experiment, while another group received Vivonex alone. The remaining three groups received added cholesterol exclusively before, during or after the ten week DMH induction period. The experiment continued for over 500 days, and was evaluated by comparing, between groups, the time taken for the development of objective signs of colonic disease (time to tumour presentation or TTP). Animals either died spontaneously or were killed and autopsied. Colon cancers were confirmed histologically in every animal. The results showed that cholesterol feeding throughout the experiment or during the DMH induction period reduced the TTP compared to controls (p less than 0.05). Cholesterol prefeeding had no such effect. In the after group, the TTP was correspondingly delayed (p less than 0.05). Cholesterol-fed controls and groups receiving cholesterol during or after the DMH induction had more colon tumours and/or a greater incidence of metastases than cholesterol-free controls or those pre-fed cholesterol. The findings indicate a direct relationship between timing of cholesterol exposure and signs of colon cancer, and demonstrate that dietary cholesterol has promoter-like characteristics.

1,2-Dimethylhydrazine↗
PubMed1983

Sequence analysis of 28S ribosomal DNA from the amphibian Xenopus laevis.

We have determined the complete nucleotide sequence of Xenopus laevis 28S rDNA (4110 bp). In order to locate evolutionarily conserved regions within rDNA, we compared the Xenopus 28S sequence to homologous rDNA sequences from yeast, Physarum, and E. coli. Numerous regions of sequence homology are dispersed throughout the entire length of rDNA from all four organisms. These conserved regions have a higher A + T base composition than the remainder of the rDNA. The Xenopus 28S rDNA has nine major areas of sequence inserted when compared to E. coli 23S rDNA. The total base composition of these inserts in Xenopus is 83% G + C, and is generally responsible for the high (66%) G + C content of Xenopus 28S rDNA as a whole. Although the length of the inserted sequences varies, the inserts are found in the same relative positions in yeast 26S, Physarum 26S, and Xenopus 28S rDNAs. In one insert there are 25 bases completely conserved between the various eukaryotes, suggesting that this area is important for eukaryotic ribosomes. The other inserts differ in sequence between species and may or may not play a functional role.

Animals↗
PubMed1983

Nonspecific ulcerative colitis as a sequel to amebic dysentery.

In two patients, treatment of amebic dysentery was followed (despite the disappearance of the infecting organism) by an illness with the clinical, pathological, and radiological characteristics of nonspecific ulcerative colitis. Their case histories indicate that in addition to persistent or recurrent amebic infection, the irritable colon syndrome, and ulcerative postdysenteric colitis, nonspecific ulcerative colitis should be kept in mind in the evaluation and therapy of continuing symptoms in patients with treated amebic dysentery.

Adult↗
PubMed1983

Effect of sodium taurocholate on gastric secretion in patients with duodenal ulceration.

The effect of sodium taurocholate instillation on the stimulated stomachs of patients with duodenal ulceration has been investigated. Instillation into the stomach of sodium taurocholate significantly reduced pentagastrin stimulated volume and outputs of both acid and sodium, with no change in the calculated volume of duodenogastric reflux. These observations are not consistent with the back-diffusion theory, but suggest direct parietal cell inhibition of gastric secretion by sodium taurocholate.

Duodenal Ulcer↗
PubMed1983

Histochemical changes in mucus in duodenal ulceration.

In duodenal ulceration the Alcian blue staining acid mucosubstances in goblet cells are reduced and the goblet cells themselves disappear. At the same time periodic acid-Schiff (PAS) staining neutral mucosubstances appear in the cells of the surface epithelium. These changes have been measured quantitatively with the help of a Vickers M86/0010 Scanning and Integrated Microdensitometer. During healing the changes are reversed. It is suggested that these changes suggest a metaplasia towards a gastric type mucosa as a protective response to the presence of ulceration.

Cell Count↗