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Biomedical subjects

L M Ryan

Publications and source records attributed to L M Ryan.

135 records · Page 8Linked to original sources

Renal proximal tubular dysfunction and paroxysmal nocturnal hemoglobinuria.

A patient with paroxysmal nocturnal hemoglobinuria, who required many blood transfusions for hemolytic episodes, had a persistent hyperchloremic metabolic acidosis. Bicarbonate infusion demonstrated a large fractional excretion of bicarbonate (28.6 per cent at a plasma bicarbonate level of 23 meq/liter) which was consistent with proximal renal tubular acidosis. Generalized aminoaciduria and decreased tubular reabsorption of phosphate were also present. Marked deposition of iron in renal proximal tubules was associated with these functional abnormalities. We believe that, as systemic acidosis can promote hemolysis in patients with paroxysmal nocturnal hemoglobinuria, hemolysis can lead, by way of iron deposition in renal tubules, to further acidosis. This cycle should be interrupted with appropriate doses of bicarbonate.

Acidosis, Renal Tubular↗

High prevalence of HLA-Cw1 and Cw2 antigens in spondylarthritis.

HLA-B27 is frequently, but not invariably, found in patients with spondylarthritic diseases. Recently it has been shown that HLA-C-locus antigens w1 and w2 (w1/2) are in linkage disequilibrium with B27. A group of 139 patients with seronegative arthritis or spondylitis has been studied to determine the clinical and radiographic features associated with these antigens. An increased frequency of spondylarthritis was present in HLA-B27-negative, Cw1/2-positive patients when compared with B27- and Cw1/2-negative patients (P less than 0.01). In addition, a large group of patients who did not fulfill accepted criteria for a specific spondylarthritic syndrome were identified; the frequency of both HLA-B27 and Cw1/2 was greater in these individuals than in healthy blood donors. Thus HLA-Cw1/2 are spondylitis-associated antigens. These findings suggest that the critical genetic locus is neither B27 nor Cw1/2 but is a closely linked gene.

Arthritis, Reactive↗

Issues of efficiency in combining proportions of deaths from several clinical trials.

The Mantel-Haenszel test provides a straightforward method to combine results from several clinical trials when only summary information, such as the proportion of deaths, is available for each trial. More efficient tests, such as the stratified logrank test, should be used if the survival and censoring times are known for all individuals, but in practice, the cost and effort of obtaining this information may be prohibitive. The purpose of this paper is to derive a general expression for the asymptotic relative efficiency (ARE) of the Mantel-Haenszel test with respect to the stratified logrank test, and to compute the ARE in situations which are likely to be of practical interest. The results show that under realistic assumptions about the survival distribution, losses to follow-up and duration of accrual, the ARE frequently exceeds 80 per cent. An example is given to show the usefulness of the approach when combining proportions of deaths from several cancer clinical trials.

Clinical Trials as Topic↗

PALA versus streptozotocin, doxorubicin, and MeCCNU in the treatment of patients with advanced pancreatic carcinoma.

Seventy-three eligible, chemotherapy-naive, ambulatory patients with advanced pancreatic carcinoma were allocated to one of two treatment regimens: 35 received PALA (1250 mg/m2 daily x 5 every 4 weeks) and 38 were given SAM (streptozotocin 400 mg/m2 i.v. daily x 5, doxorubicin 45 mg/m2 i.v. on day 1 and 22, and methyl CCNU 60 mg/m2 orally on days 1 and 22 every 6 weeks). Doses were modified for myelo-, gi-, or cardiotoxicity. Adequate organ, bone marrow and cardiac function; a measurable lesion; adequate caloric intake; and a life expectancy of 2 months were required for treatment on this trial. One patient on each regimen had a partial response for response rates of 3% (95% confidence intervals, 0.08 to 17%). Median survival on the PALA arm was 5 months and median time to treatment failure was 2.6 months. SAM patients experienced median overall and progression free survivals of 3.4 and 1.9 months, respectively. The severe toxicity observed was almost exclusively myelosuppression on both regimens. One patient receiving SAM had lethal leukopenic sepsis during the first cycle as the only treatment-related death. Neither PALA nor SAM offer any therapeutic utility to patients with advanced pancreatic cancer.

Adult↗

Polymorphisms in GSTT1 and p53 and urinary transitional cell carcinoma in south-western Taiwan: a preliminary study.

Little is known about the relevance of genetic polymorphisms to arsenic-related bladder cancer. A preliminary case-control study was conducted to explore the association between genetic polymorphisms of GSTT1, p53 codon 72 and bladder cancer in southern Taiwan, a former high arsenic exposure area. Fifty-nine urinary transitional cell carcinoma (TCC) patients from a referral centre in south-western Taiwan and 81 community controls matched on residence were recruited from 1996 to 1999. A questionnaire was administered to obtain arsenic exposure and general health information. Genotypes of p53 codon 72 and GSTT1 were analysed by polymerase chain reaction-restriction fragment length polymerase. The combined variant genotypes (heterozygous or homozygous variant) of p53 codon 72 and GSTT1 null were observed in 29% of cases and in 44% of controls, respectively. In this preliminary study, bladder cancer risk was slightly elevated for subjects carrying the variant genotype of p53 codon 72 or in subjects carrying the GSTT1 null genotype. Variants in p53 codon 72 increased the risk of bladder cancer among smokers. However, the results were not statistically significant and larger confirmatory studies are needed to clarify the role of candidate gene polymorphisms and bladder cancer risk in arsenic exposed populations.

Adult↗

Amyloid arthropathy: possible association with chondrocalcinosis.

Three patients with symptomatic articular or periarticular amyloidosis associated with chondrocalcinosis are reported. None of these patients had evidence of dysproteinemia which has been considered the primary predisposing factor in amyloid arthropathy. The clinical features of these patients are described and possible pathogenesis discussed.

Aged↗