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Biomedical subjects

N Walker

Publications and source records attributed to N Walker.

At least 19 recordsLinked to original sources
PubMed1992

Regulation of the maize HRGP gene expression by ethylene and wounding. mRNA accumulation and qualitative expression analysis of the promoter by microprojectile bombardment.

The expression of the maize gene coding for a hydroxyproline-rich glycoprotein (HRGP) has been studied by measuring the mRNA accumulation after wounding or ethylene treatment. RNA blot and in situ hybridization techniques have been used. The temporal and tissue-specific expression has been observed: the cells related to the vascular system show the more intense HRGP mRNA accumulation. Transcriptional constructions of the maize HRGP promoter have been tested on different maize tissues by microbombarding. A 582 bp promoter is able to direct the expression of the gus gene on calli and young leaves. Constructions having shorter promoter sequences lose this ability. The 582 bp construction retains the general specificity of expression observed for the HRGP gene.

Ethylenes↗
PubMed1992

Bilateral scapular fractures secondary to electrical shock.

Fractures of the scapula are rare injuries. Usually the scapula requires a high-energy impact to sustain a fracture. Various fractures have been noted as a result of convulsive seizures. We report bilateral scapular fractures caused by electric shock and discuss their pathomechanical origin.

Electric Injuries↗
PubMed1992

Sclerosing peritonitis with gross peritoneal calcification: a case report.

We report the case of a patient on dialysis for 13 years, including continuous ambulatory peritoneal dialysis (CAPD) for 11 years, who developed sclerosing peritonitis with gross peritoneal calcification. The patient first presented with abdominal pain in January 1990, when peritoneal calcification was detected for the first time. Her symptoms settled spontaneously and 1 year later she presented with acute peritonitis and adynamic ileus. The peritonitis settled with antibiotics and Tenchkoff catheter removal, but the ileus persisted. She was commenced on long-term parenteral nutrition, but never recovered useful bowel function. After 8 weeks of hemodialysis and total parenteral nutrition, a further laparotomy for an acute abdomen showed what appeared to be extensive bowel infarction and peritoneal calcification. She died several days later. Of significance, peritoneal calcification was first noted on x-ray and computed tomography (CT) scan while the patient was still largely asymptomatic and before peritoneal ultrafiltration capacity was significantly impaired. Unlike other reported cases of calcifying peritonitis, sclerosing peritonitis was present and calcification was far more extensive. It was not associated with factors such as frequent infective peritonitis or acetate dialysate. Calciphylaxis was not present nor was there any abnormality of calcium-phosphate metabolism. The outcome of this case suggests that patients with recurrent or persistent bowel symptoms on long-term CAPD should have early abdominal x-ray or CT scanning to exclude sclerosing peritonitis or bowel calcification. If present, consideration should be given to transferring the patient to another therapeutic dialysis modality if possible.

Adult↗
PubMed1992

Piroxicam induced submassive necrosis of the liver.

Several widely used non-steroidal anti-inflammatory drugs have been reported as causing severe hepatitis. Three cases of severe acute hepatitis have been reported in association with piroxicam. A fatal submassive necrosis that occurred in a 68 year old lady who had received piroxicam for 15 months is described. A 48 year old man who developed submassive hepatic necrosis six weeks after beginning piroxicam but was successfully treated with orthotopic liver transplantation is also reported. Piroxicam may induce submassive necrosis of the liver, probably as an idiosyncratic reaction.

Aged↗
PubMed1991

Predicting cholangiocarcinoma in patients with primary sclerosing cholangitis before transplantation.

Patients with primary sclerosing cholangitis are at an increased risk of developing cholangiocarcinoma, which is difficult to diagnose because the biliary tree is already distorted. Eleven patients with primary sclerosing cholangitis who underwent orthotopic liver transplantation at this hospital were evaluated. Four patients had coincidental histologically proved cholangiocarcinoma. Patients with cholangiocarcinoma in contrast to patients without tumour presented with rapid onset of persistent jaundice, pruritus, and weight loss associated with an appreciable rise in bilirubin (8x v 2x) and alkaline phosphatase (3.5x v 1.2x) over one year. Cholangiography and computed tomography showed appreciably dilated intrahepatic bile ducts (3/4 v 0/7). The diagnosis of cholangiocarcinoma could only be established before operation in one patient by fine needle aspiration cytology. Tumour was recognised at operation in one other. Histological examination of hepatectomy specimens showed that patients with cholangiocarcinoma had less advanced histological features of primary sclerosing cholangitis. Multiple areas of carcinoembryonic antigen positive epithelial atypia and carcinoma in situ were found in all patients with cholangiocarcinoma. Cholangiocarcinoma recurred in two patients at 14 and 39 months after transplantation. Superimposed cholangiocarcinoma can be predicted in most patients with cholangitis before transplantation, although a definitive diagnosis is difficult to make. Their prognosis after successful transplantation is guarded.

Adenoma, Bile Duct↗
PubMed1991

Only patients with dysplasia progress to adenocarcinoma in Barrett's oesophagus.

Columnar lined oesophagus (Barrett's oesophagus) carries a risk for the development of adenocarcinoma. Epithelial dysplasia appears to be a precursor but the utility of this marker for predicting subsequent adenocarcinoma is unsettled. We therefore prospectively studied 81 patients with histologically proven columnar epithelium of at least the distal 3 cm of the tubular oesophagus with regular endoscopic biopsies for a total of 289.2 patient years (mean 3.6 years, range 0.5-8). Twenty three patients (28%) had epithelial dysplasia detected during follow up. Both patients with persistent high grade dysplasia present on initial biopsies developed adenocarcinoma after 2.6-4.5 years, despite the absence of gross macroscopic change. The initial single layer pleomorphic high grade dysplasia in one patient regressed to low grade dysplasia which has persisted for 1.5 years. Of 10 patients with initial low grade dysplasia, one progressed to adenocarcinoma in 4.3 years. The low grade dysplasia persisted unchanged in seven patients for 1.5-7 years and appears to have regressed in two patients after three to five years. Ten patients developed low grade dysplasia during the surveillance period. This has persisted unchanged in six patients from 0.5-5 years, regressed in three for 0.5-5 years and has appeared after the first yearly biopsy in one patient. No patient without dysplasia has developed adenocarcinoma. The incidence of adenocarcinoma in Barrett's oesophagus in this study is one case per 96 patient years. This is 61 times (95% confidence limits 12-176) the age adjusted incidence of oesophageal cancer in Australia. Persistent high grade dysplasia appears to be a sensitive indicator for the development of subsequent adenocarcinoma.

Adenocarcinoma↗
PubMed1991

Dangerous mistakes.

The shortening of the periods of detention for treatment, deterrence or retribution have made a live issue of whether (or when) it is justifiable to detain violent and sexual offenders solely for the protection of others. Anti-protectionist arguments have made 'dangerousness' a dirty word, but are based either on actuarial statistics of doubtful relevance or on confused moral reasoning. A typology of 'dangerousness' is tentatively offered, and the impossibility of adequately supervising some dangerous offenders in the community is emphasised. That said, offenders detained solely for the sake of others are entitled to more than merely 'humane containment'.

Commitment of Persons with Psychiatric Disorders↗
PubMed1990

Flucloxacillin induced delayed cholestatic hepatitis.

We report four cases of severe delayed cholestatic hepatitis induced by flucloxacillin. All patients presented with deep jaundice and pruritus which developed soon after ceasing flucloxacillin. Liver function tests were abnormal in all patients with markedly elevated serum bilirubin concentration, alkaline phosphatase and aspartate transaminase levels. Extrahepatic biliary obstruction and infective hepatitis were excluded in all cases. Liver biopsies showed centrilobular cholestasis with portal and lobular inflammation and eosinophil infiltration. Although symptoms resolved within six weeks in all patients, cholestatic liver function tests have persisted in two patients for more than six months. With the increasing usage of this drug and the delayed presentation of cholestasis, flucloxacillin needs to be considered in the differential diagnosis of all patients presenting with cholestatic jaundice.

Aged↗
PubMed1989

Life experiences, response styles and mental health among mothers and children in Beirut, Lebanon.

A sample of 152 women living in Beirut, Lebanon was studied to determine the relationship between life experiences, mothers' depression, and children's health and behavior. Measures of the perceived negative impact of both war and nonwar related events, measures of available social support, sociodemographic variables, coping or response strategies and displacement were used to predict mothers' depressive symptomatology and their children's health. The level of perceived negative impact of war-related events was found to be strongly associated with higher levels of depressive symptomatology among mothers. More surprising was the relative importance of experiences unrelated to the war in predicting higher levels of depressive symptoms. Among the most noteworthy of the findings was the association between the use of an emotional response style and the measure of psychological dysfunction. Finally, the level of a mother's depressive symptomatology was found to be the best predictor of her child's reported morbidity, with higher levels of symptoms associated with higher levels of morbidity.

Child↗
PubMed1987

The heparin-induced thrombocytopenia syndrome: an update.

One hundred sixty-nine patients with heparin-induced thrombocytopenia are reported and compared with the 62 patients reported in 1983. Prompt recognition of heparin-induced thrombocytopenia and immediate cessation of heparin administration lowered the complication and death rates from 61% (38/62) to 22.5% (38/169) and from 23% (14/62) to 12% (21/169), respectively. Platlet count and duration of heparin administration were not useful in predicting the outcome of the heparin-induced thrombocytopenia syndrome. Patients who received heparin in therapeutic doses were at higher risk for developing complications than were patients receiving lower doses of heparin. Platelet aggregation tests became negative as early as 7 days after discontinuation of heparin but persisted as long as 28 months. Heparin reexposure (2 days to 34 months after positive aggregation studies) was uneventful in 13 of 15 patients, whereas two patients suffered devastating thrombotic complications. Five patients continued to receive heparin despite positive platelet aggregation tests. The serious complications suffered by two of these five patients illustrate the necessity to discontinue heparin as soon as the diagnosis of heparin-induced thrombocytopenia is established.

Adolescent↗
PubMed1985

Isolation of the gene encoding adenylate cyclase in Saccharomyces cerevisiae.

By complementation of the cyr1-1 mutation in Saccharomyces cerevisiae, we have isolated yeast genomic DNA containing the structural gene that encodes the catalytic unit of adenylate cyclase (EC 4.6.1.1). The isolated DNA restored adenylate cyclase activity to cyr1-1 mutants and directed integration at the CYR1 locus. Wild-type strains transformed with CYR1 DNA on the high copy number vector YEp24 contained 4- to 6-fold more adenylate cyclase activity than strains carrying the plasmid with no insert. This result suggests that expression of the CYR1 gene product, rather than that of other polypeptide components of the adenylate cyclase system, limits total adenylate cyclase activity in S. cerevisiae. CYR1-containing plasmids also complemented the temperature-sensitive growth defect of the cell division cycle mutation cdc35-1, which confers a phenotype under restrictive conditions similar to that of cyr1-1 and maps to the same locus. Further, cdc35-1 cam mutants, which contain mutations that enable them to take up cAMP from the medium, grew at the restrictive temperature in the presence of exogenous cAMP. These observations support the view that CDC35 and CYR1 are allelic and confirm the hypothesis that cAMP synthesis is required for cells to pass through the "start" position of the cell division cycle.

Adenylyl Cyclases↗
PubMed1979

[The possibility of isolated joint transplantation with microsurgery of the blood vessels].

The transplantation of isolated joints with intact blood supply and good biomechanic conditions is possible. Biomechanical and neurotropic disturbances lead eventually to progressive degenerative alterations. The regularly seen periarticular adhesions with reduced joint mobility may also reduce the clinical application. Considering our very good results of joint-replantation also good clinical results of the transplantation with vascular and neural anastomoses may be expected. Microsurgery has a proven place for bridging great bone defects with vascular bone fragments. Histological examinations show a prompt and regular bone metabolism in the transplanted bone.

Animals↗
PubMed1979

Single cilia in the articular cartilage of the cat.

Single cilia (SC) in the articular cartilage of the cat are described with regard to structure, frequency and intracellular location. Comparison is made with their occurrence in the cartilage of other species or in other tissues; special consideration is given to their developmental stages. In the 1-year-old cat examined, about 20% of the cells showed SC with a predominantly intracellular course and some of them did not reach the extracellular space at all. Cross-sections of the proximal region of SC reveal the familiary 9+0 pattern; towards the distal end, the number of doublets and the diameter of the shaft are decreasing. It is concluded that most of the SC encountered are undergoing involution.

Animals↗
PubMed1979

[On the surgical treatment of paraplegia (author's transl)].

We report on a modified dorso-ventral operation method for the treatment of unstable vertebral lesions in parapletic patients. We see the indication for ca. 10% of the paraplegics with unstable vertebral fractures and incomplete neurological pareses with a real of expected worsening of the neurological status. A real stabilisation can only be reached by combined dorsal and ventral fusioning, which only rectify the operative risks. The geometrical arguments for this method are presented.

Adult↗