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Biomedical subjects

S A Cooke

Publications and source records attributed to S A Cooke.

At least 19 recordsLinked to original sources
PubMed2001

Pre-reactive complexes in mixtures of water vapour with halogens: characterisation of H2O...ClF and H2O...F2 by a combination of rotational spectroscopy and ab initio calculations.

Complexes H2O...ClF and H2O...F2 were detected by means of their ground-state rotational spectra in mixtures of water vapour with chlorine monofluoride and difluorine, respectively. A fast-mixing nozzle was used in conjunction with a pulsed-jet, Fourier-transform microwave spectrometer to preclude the vigorous chemical reaction that these dihalogen species undergo with water. The ground-state spectra of seven isotopomers (H2 16O...35ClF, H2 16O...ClF, H2 18O...35ClF, D2 16O... 35ClF, D2 16O...37ClF, HDO...35ClF and HDO...37ClF) of the ClF complex and five isotopomers (H2O...F2, H2 18O...F2, D2O...F2, D2 18O...Fi and HDO...F2) of the F2 complex were analysed to yield rotational constants, quartic centrifugal distortion constants and nuclear hyperfine coupling constants. These spectroscopic constants were interpreted with the aid of simple models of the complexes to give effective geometries and intermolecular stretching force constants. Isotopic substitution showed that in each complex the H2O molecule acts as the electron donor and either CIF or F2 acts as the electron acceptor, with nuclei in the order H2O...ClF or H2O...F2. For H2O...ClF, the angle phi between the bisector of the HOH angle and the O...Cl internuclear line has the value 58.9(16)degrees, while the distance r(O...Cl)= 2.6081(23) A. The corresponding quantities for H2O...F2 are phi = 48.5(21)degrees and r(O...Fi) = 2.7480(27) A, where Fi indicates the inner F atom. The potential energy V(phi) as a function of the angle phi was obtained from ab initio calculations at the aug-cc-pVDZ/MP2 level of theory for each complex by carrying out geometry optimisations at fixed values of phi in the range +/-80degrees. The global minimum corresponded to a complex of Cs symmetry with a pyramidal configuration at O in each. The function V(phi) was of the double-minimum type in each case with equilibrium values phie = +/-55.8degrees and +/-40.5degrees for H2O...ClF and H2O...F2, respectively. The barrier at the planar C2v conformation was V0= 174cm(-1) for H2O...ClF and 7cm(-1) for H2O...F2. For the latter complex, the zero-point energy level lies above the top of the barrier.

Journal Article↗
PubMed1981

The surgical treatment of the radiation-damaged rectum.

Details are given of 37 consecutive patients with radiation damage to the rectum. Twenty-eight presented with rectovaginal fistulas, 3 with haemorrhage from ulcerative proctitis, 3 with low rectal strictures, 2 with a painful rectal ulcer and 1 with a rectal carcinoma. Thirty-five of the 37 had been treated for carcinoma of the cervix, and of these, 30 were Black South African women in whom this disease forms approximately 70 per cent of all malignancies. Associated pathology in these patients included urinary fistulas, small bowel fistulas or stenoses and a variable degree of fibrosis of the pelvic cellular tissue. Treatment involved subtotal rectal resection with restoration of continuity by means of a peranal sleeve anastomosis between healthy colon and the rectal stump denuded of its mucosa. Technical success was achieved in 35 of the 37 patients, with no mortality. The functional results were assessed both subjectively and objectively in 31 patients followed up for more than 6 months. Full continence was achieved in 54 per cent initially, improving to 75 per cent (21 of 28) at 1 year postoperatively. At 1 year, variable degrees of incontinence for a liquid stool persisted in 7 of 9 patients who had low fistulas with a low anastomosis at dentate line level. Where anastomosis was possible at a higher level, all 19 patients cured of fistula, ulcer, stenosis or haemorrhagic proctitis were fully continent at 1 year.

Adult↗
PubMed1981

Polyps and colorectal cancer in South African Blacks.

This study reflects the fact that cancer of the large bowel is uncommon in South African Blacks, and that colorectal polyps do not appear to constitute a precursor to most colorectal cancers. Furthermore, it is shown that dietary factors associated with this cancer in Western populations are not evident in the Black population. In the South African White population, however, the disease behaves in a similar way to that observed in Western countries. Other definitive differences found were the absence of multiple synchronous cancers and diverticular disease in the Blacks with colorectal cancer. It is thus postulated that dietary factors are absent, or have not been present for a sufficient length of time to influence the development of polyps or polyp--cancer sequence in this population. It is also possible that the adenoma--carcinoma progression observed in Western countries may not be relevant to the development of all colorectal carcinomas in communities such as those reported here.

Adolescent↗
PubMed1978

Transanal anastomosis in the treatment of low rectal strictures due to tribal enemas.

Enema administration is common in Black tribal communities. In the urban environment, toxic and corrosive ingredients may be used which can lead to severe complications. The diagnosis and principles of treatment of complicated proctocolitis of enema origin are discussed. The management of 2 patients who developed long stricutres extending low into the rectum is described. After subtotal rectal and sigmoid resection, continuity was successfully restored using a transanal sleeve anastomosis. Subsequent continence was normal in both patients.

Adult↗
PubMed1978

Polyposis coli. The clinical spectrum in adults.

Four patients are reported, to illustrate the wide spectrum of colonic polyps which may occur in multiple form in adults. Included are unusual cases of metaplastic and juvenile polyposis. The subject is reviewed, and the need for accurate histological diagnosis is stressed. The possibility that the difference between familial adenomatous polyposis and Gardner's syndrome may lie merely in the degree of expressivity of the associated extracolonic features is discussed. Surveillance of these patients for peri-ampullary neoplasms in the duodenum is considered. The interrelationship between familial adenomatous polyposis, juvenile polyposis and colorectal cancer is discussed.

Adenocarcinoma↗
PubMed1977

Rectal resection for tumour with transanal anastomosis and sphincter preservation.

Resection of the rectum, with restoration of continuity by means of a primary, transanal, anocolic anastomosis, is a useful method in the treatment of certain rectal tumours. It particularly fills a need in the management of tumours of the lower rectum where anterior resection is indicated but is technically difficult and liable to complications, or where it is not possible and would be abandoned in favour of abdominoperineal excision of the rectum with a permanent colostomy. The pathological criteria, technical factors and functional results which justify the use of this procedure are discussed. The principles of the operation are described, and 2 illustrative cases are reported. The large size, low site and pathological nature of both the malignant carcinoid tumour and the leiomyoma were such that total rectal resection was obligatory, the object being palliation in the former and cure in the latter. Both patients were continent after the operation. The place of this operation in the treatment of adenocarcinoma of the rectum is discussed.

Adult↗
PubMed1977

Non-occlusive ischaemic colitis in a South African black. A case report.

A rare case of non-occlusive ischaemic colitis in a South African Black is described. The appearance of the bowel at an initial operation, and the histopathological changes demonstrated in the resected specimen after a subsequent operation, provide evidence for this diagnosis. The clinical presentation and radiological features which were also compatible with the diagnosis are presented. While the initiating mechanism remains obscure, it is suggested that ischaemia of the colon wall is likely to have been responsible for the final histopathological picture in this case.

Adult↗
PubMed1977

The significance of starch powder contamination in the aetiology of peritoneal adhesions.

The presence or absence of starch granulomas on the peritoneal surface or within peritoneal adhesions is reported in 20 patients subjected to a second laparotomy. Evidence is presented to show that starch granuloma formation is common in the early months following operation and that adhesions associated with starch granulomas cause intestinal obstruction. It is suggested that although starch is usually absorbed within 2 years, associated band adhesions may persist. Glove powder contamination of the peritoneal cavity may thus be a common cause of band adhesion obstruction.

Granuloma↗
PubMed1977

Perforated duodenal ulcer in the black population of Central Johannesburg.

The increasing incidence of perforated duodenal ulcer among Black patients admitted to the Johannesburg General Hospital between 1966 and 1976 is described against a background of the different forms of peptic ulcer disease seen in this hospital population. Admission for perforation during the years 1973-6 was as common among Black as among White patients. Perforation occurred principally in young (20-40 years) Black males (sex ratio 14 : 1), with a short history of preceding symptoms, and treatment was usually by simple closure. In the White group the age range was broader (20-70 years) and the male : female ratio only 2.7 : 1. Duodenal ulcer occurred predominantly in males (ratio 6 : 1), and the spectrum of the disease among the Black population in this urban environment resembled that among the White population in Johannesburg and in Western countries in the relative frequency of perforation and haemorrhage, rarity of stenosis and ratio of duodenal to gastric ulceration.

Adult↗
PubMed1977

Establishing a normal peer as a behavioral model for developmentally delayed toddlers.

The present investigation demonstrated a systematic teaching procedure for establishing a normal toddler as a peer-model for three children showing delayed development, each one under 27 mo. of age. For each delayed subject, training consisted of adult-directed prompting and social reinforcement contingent upon the delayed children's imitations of material use and motor responses emitted by a normal peer. Within-subjects multiple-baseline designs across responses were used to demonstrate intrasubject control over imitative responding. Indices of stimulus and response generalization were assessed through having the peer-model present the trained responses along with untrained responses in a situation free of adult prompting and social reinforcement for imitative responding. Results indicated that the training in peer-imitation was successful for establishing the peer-model's behavior in a stimulus control relationship with the imitative responding of the delayed children. Moreover, the findings generally demonstrated transfer of training across stimulus situations and responses. Implications for educational programming with developmentally delayed children are discussed.

Behavior Therapy↗