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Biomedical subjects

I Cockburn

Publications and source records attributed to I Cockburn.

12 recordsLinked to original sources
PubMed2005

A complement receptor-1 polymorphism with high frequency in malaria endemic regions of Asia but not Africa.

Complement receptor-1 (CR1) is a ligand for rosette formation, a phenomenon associated with cerebral malaria (CM). Binding is dependent on erythrocyte CR1 copy number. In Caucasians, low CR1 expressors have two linked mutations. We determined the Q981H and HindIII RFLP distribution in differing population groups to ascertain a possible role in adaptive evolution. We examined 194 Caucasians, 180 Choctaw Indians, 93 Chinese-Taiwanese, 304 Cambodians, 89 Papua New Guineans (PNG) and 366 Africans. PCR/RFLP used HindIII for CR1 expression and BstNI for the Q981H mutation. DNA sequencing and pyrosequencing were performed to resolve inconclusive results. Gene frequencies for the L allele were 0.15 in Africans, 0.16 in Choctaws, 0.18 in Caucasians, 0.29 in Chinese-Taiwanese, 0.47 in Cambodians and 0.58 in PNG. Allelic frequency for 981H were 0.07 in Africans, 0.15 in Caucasians, 0.18 in Choctaws, 0.29 in Chinese-Taiwanese, 0.47 in Cambodians and 0.54 in PNG. The Q981H polymorphism correlates with the HindIII RFLP in most groups except West Africans and appears to be part of a low CR1 expression haplotype. The gene frequency for the haplotype is highest in the malaria-endemic areas of Asia, suggesting that this haplotype may have evolved because it protects from rosetting and CM.

Africa↗
PubMed1999

Review article: rabeprazole's tolerability profile in clinical trials.

Rabeprazole is a new member of a class of substituted benzimidazole drugs known as proton pump inhibitors. Comparative trials have demonstrated that it is at least as effective as omeprazole for the treatment of gastrooesophageal reflux disease (GERD), duodenal ulcers, or gastric ulcers. It is significantly more effective than histamine2-receptor antagonists for acid suppression, GERD healing and pain relief, and duodenal ulcer healing and pain relief. Adverse events reported during clinical trials provide an important indication of a medication's tolerability. We demonstrate that rabeprazole has a favourable adverse events profile. It is well tolerated in placebo-controlled studies and comparative trials with omeprazole and H2-receptor antagonists. Moreover, no dose adjustments are required for special populations, such as the elderly or patients with renal or mild-to-moderate hepatic disease. Adverse events data from clinical trials support the use of rabeprazole as a treatment for acid-related diseases.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1997

Characteristics of demand for pharmaceutical products: an examination of four cephalosporins.

We model demand for four cephalosporins and compute own- and cross-price elasticities between branded and generic versions of the four drugs. We model demand as a multistage budgeting problem, and we argue that such a model is appropriate to the multistage nature of the purchase of pharmaceutical products, in particular the prescribing and dispensing stages. We find quite high elasticities between generic substitutes and also significant elasticities between some therapeutic substitutes.

Cephalosporins↗
PubMed1996

Public-private interaction in pharmaceutical research.

We empirically examine interaction between the public and private sectors in pharmaceutical research using qualitative data on the drug discovery process and quantitative data on the incidence of coauthorship between public and private institutions. We find evidence of significant reciprocal interaction, and reject a simple "linear" dichotomous model in which the public sector performs basic research and the private sector exploits it. Linkages to the public sector differ across firms, reflecting variation in internal incentives and policy choices, and the nature of these linkages correlates with their research performance.

Academies and Institutes↗
PubMed1996

Scale, scope, and spillovers: the determinants of research productivity in drug discovery.

We examine the relationship between firm size and research productivity in the pharmaceutical industry. Using detailed internal firm data, we find that larger research efforts are more productive, not only because they enjoy economies of scale, but also because they realize economies of scope by sustaining diverse portfolios of research projects that capture internal and external knowledge spillovers. In pharmaceuticals, economies of scope in research are important in shaping the boundaries of the firm, and it may be worth tolerating the static efficiency loss attributable to the market power of large firms in exchange for their superior innovative performance.

Drug Industry↗
PubMed1996

Mixed Poisson regression models with covariate dependent rates.

This paper studies a class of Poisson mixture models that includes covariates in rates. This model contains Poisson regression and independent Poisson mixtures as special cases. Estimation methods based on the EM and quasi-Newton algorithms, properties of these estimates, a model selection procedure, residual analysis, and goodness-of-fit test are discussed. A Monte Carlo study investigates implementation and model choice issues. This methodology is used to analyze seizure frequency and Ames salmonella assay data.

Algorithms↗