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Biomedical subjects

N Walker

Publications and source records attributed to N Walker.

At least 91 records · Page 5Linked to original sources
PubMed1994

Pentoxifylline therapy for chronic claudication: are patients dependent on therapy?

BACKGROUND: The purpose of this study was to evaluate the efficacy of long-term pentoxifylline therapy. METHODS: Fifty consecutive patients on long-term pentoxifylline therapy entered a weaning program. The standard dose of 400 mg three times a day was reduced to 400 mg twice a day for 1 month, 400 mg daily for an additional month, and then withdrawn completely for 3 months. Subjective evaluation of each patient's symptoms and objective measurements (treadmill testing for initial claudication distance, maximum walking distance, and ankle/brachial indexes) were evaluated during treatment withdrawal. RESULTS: Twenty-seven patients tolerated withdrawal of therapy without symptomatic deterioration. Seven of nine patients who did not tolerate weaning had deterioration of treadmill ICD/MWD parameters; there was a significant absolute decrease (p = 0.016) in MWD from 430 +/- 78 to 221 +/- 23 feet. Patients with an initial low MWD were less likely to tolerate weaning. Sixty percent of the patients with successful weaning had clinically asymptomatic deterioration of treadmill ICD/MWD parameters. CONCLUSIONS: A substantial number of patients who have been on long-term successful pentoxifylline therapy for claudication can be weaned from the drug. Asymptomatic deterioration of treadmill test parameters is not an indication for resuming therapy.

Aged↗
PubMed1993

Activation and repression of Drosophila alcohol dehydrogenase distal transcription by two steroid hormone receptor superfamily members binding to a common response element.

Developmental activation of the Drosophila alcohol dehydrogenase (Adh) distal promoter is controlled by the Adh adult enhancer (AAE). Within this 150 bp, complex enhancer is a small (12 bp) positive cis-acting element that is required for high levels of distal transcription in adult flies and ADH-expressing tissue culture cells. We previously reported that the steroid receptor superfamily member FTZ-F1 binds to this site. We have identified a second steroid receptor superfamily member, DHR39, which also binds to this site. DHR39 is expressed throughout development in transcripts of several sizes. In situ hybridization to embryos has shown that DHR39 RNA is found primarily in the central nervous system, and not in embryonic tissues that express ADH. FTZ-F1 RNA, however, shows temporal-specific patterns similar to those of the distal promoter. FTZ-F1 and DHR39 have identical amino acids in the 'P-box' of the DNA binding domain, suggesting that they have identical DNA recognition characteristics. By electrophoretic mobility shift analysis we show that a DHR39 fusion protein binds specifically to two FTZ-F1 binding sites. By over expressing the full length DHR39 protein in a transient co-transfection assay we have shown that it represses distal Adh expression in a dosage- and binding site-dependent manner. Over expression of an alternative DHR39 open reading frame that lacks part of the putative ligand binding domain does not alter Adh expression. In contrast, over expression of FTZ-F1 specifically activates distal Adh expression.

Alcohol Dehydrogenase↗
PubMed1993

Hepatitis B virus infection in liver allografts.

Liver transplantation of hepatitis B surface antigen (HBsAg)-positive patients has been associated with high morbidity and mortality secondary to hepatitis B (HB) recurrence in the graft. Eight patients of the Queensland Liver Transplant Service were HBsAg positive pretransplant. Six acquired HB infection of the graft, one developed serological recurrence of HB before early death from sepsis, and one HB e antigen-negative patient permanently cleared the virus. HB-infected grafts showed early expression of viral antigen, acute hepatitis, fibrosing cholestatic hepatitis, chronic active hepatitis, cirrhosis, or minimal changes associated with a carrier state. Only in the latter case was HB mild and nonprogressive. Cases of fibrosing cholestatic hepatitis progressed rapidly to liver failure; they showed fibrosis and plates of ductular epithelium extending from portal tracts into lobules, cholestasis, ballooning of hepatocytes, and prominent hepatocyte expression of viral antigens. Perioperative HB immunoglobulin proved ineffective in preventing HB recurrence. One other patient became HBsAg positive for the first time after retransplantation; he developed severe acute hepatitis, then chronic active hepatitis. Our biopsy findings support the view that, in liver allografts, the HB virus may be directly cytopathic.

Acute Disease↗
PubMed1993

Use of 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside for the isolation of beta-galactosidase-positive bacteria from municipal water supplies.

A new medium, mX-Gal, has been developed for the membrane filter enumeration of beta-galactosidase-positive bacteria in municipal water supplies. mX-Gal medium contains the chromogenic beta-galactosidase substrate 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal). All Aeromonas, Citrobacter, and Enterobacter strains isolated from raw water on mX-Gal medium were beta-galactosidase positive. In contrast, only 10 to 20% of these strains produced a red colony with a metallic sheen on m-Endo agar LES medium. Of 674 chlorinated water samples analyzed for total coliforms on m-Endo agar LES medium and for beta-galactosidase-positive bacteria on mX-Gal medium, 18 that were negative for coliforms on m-Endo agar LES showed beta-galactosidase-positive bacteria on mX-Gal. Of a total of 50 beta-galactosidase-positive bacteria isolated from these samples, 76% were identified as Aeromonas hydrophila.

Aeromonas↗
PubMed1993

Aggregation bias and the use of regression in evaluating models of human performance.

Regression analyses are increasingly being used to provide confirmatory evidence for models of human performance. The amount of information made available to judge these models is reduced because clearly established standards in the techniques of performing and reporting regression analyses are lacking. This paper addresses two primary problems in regression analysis: aggregation of data and the aggregation of variables into composite models. We provide examples of the misuse of regression techniques and recommend ways in which the amount of information made available to evaluate the model being tested can be maximized in analysis and reporting.

Bias↗
PubMed1993

Spatial and temporal characteristics of rapid cursor-positioning movements with electromechanical mice in human-computer interaction.

This research examines how people make movements with pointing devices during human-computer interaction. It specifically concerns the perceptual-motor processes that mediate the speed and accuracy of cursor positioning with electromechanical mice. In three experiments we investigated the spatial and temporal characteristics of positioning movements made with a mouse, analyzing subjects' speed and accuracy as a function of the types of targets that the movements had to reach. Experiment 1 required rapid and accurate horizontal movements to targets that were vertical ribbons located at various distances from the mouse's starting location. The targets for Experiments 2 and 3, respectively, were vertical lines having various heights and rectangular boxes having various heights and widths. Constraints on movement distance along the primary (that is, horizontal) line of motion had the greatest effects on total positioning times. However, constraints on movement distance along a secondary (vertical) line of motion also affected total positioning times significantly. These effects may be localized in different phases of movements (e.g., movement execution and verification). The duration of movement execution (i.e., physical motion) depends primarily on the target distance, whereas the duration of movement verification (i.e., check for endpoint accuracy) depends primarily on target height and width. A useful account of movement execution is provided by stochastic optimized-submovement models, which have significant implications for designing mice and menu-driven displays.

Adult↗
PubMed1993

The new bedside manner: computer terminals--implementation issues.

Even with all the adventures Beaumont has gone through (and will yet encounter), there is no question in anyone's mind that having an integrated clinical information system is a much better way to treat patients than using the paper document. Data elements input by clinicians of different departments can be grouped together and presented in a format that becomes useful information for all the caregivers. Screens and reports can be designed and tailored for any one user, so that the same data elements can be presented differently for each user. William Beaumont Hospital is providing patient care more efficiently and quicker than ever before and is able to track and monitor information in ways that imaginative practitioners are only beginning to realize and appreciate.

Computer Security↗
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↗