Synergistic cytotoxic effect of azidothymidine and recombinant interferon alpha on normal human bone marrow progenitor cells

Azidothymidine (AZT) and interferon alpha (IFN-alpha) are among the drugs showing strong in vitro activity against the human immunodeficiency virus type-1 (HIV-1). Each drug, however, has significant toxicity against normal marrow progenitor cells that frequently proves dose-limiting in patients. In this study, AZT and recombinant IFN-alpha 2a (rIFN-alpha 2a) were tested as single agents and in combination against normal myeloid (CFU-GM) and erythroid (BFU- E) colony forming cells in a standard methylcellulose culture assay. The data were analyzed using a quantitative computerized analysis based on the median-effect principle and the isobologram equation as described by Chou and Talalay (Adv Enz Regul 22:27, 1984). The ED90 for BFU-E and CFU-GM inhibition was then compared with previously measured in vivo plasma levels of each drug and the ED90 for the anti-HIV-1 effect in vitro. We demonstrate that (a) the drugs are strongly synergistic in inhibiting marrow progenitor cell growth and that this synergism occurs at drug levels that are within the range of measured plasma levels in phase I clinical trials, (b) BFU-E are more sensitive than CFU-GM to the inhibiting effects of AZT, rIFN-alpha 2a or both drugs in combination, (c) the drug concentrations in combination that synergistically inhibit bone marrow progenitors are much higher than those required to inhibit HIV-1 replication in vitro, and (d) the anti- HIV-1 effect for the combination of AZT and rIFN-alpha 2a was clearly superior to the effect of AZT or rIFN-alpha 2a alone as indicated by the combination index and the dose-reduction index. These data suggest that substantially lower doses of AZT and rIFN-alpha than those currently being tested in clinical trials might not only maintain a strong synergistic anti-HIV-1 effect but might also avoid significant hematologic toxicity.     

Growth Hormone Releasing Hormone (GHRH) and the GHRH Receptor

Reviews in Endocrine and Metabolic Disorders -     

Association of vitiligo with HLA-A2: a meta-analysis

BACKGROUND: Linkage and association studies suggest that the human leucocyte antigen (HLA) region may be involved in the genetic susceptibility of vitiligo. HLA-A2 has been reported to be associated with vitiligo in some, but not all, studies. OBJECTIVE: To identify sources of the heterogeneity among studies and to quantify effect estimates, we examined the association of HLA-A2 with vitiligo in a meta-analysis of all observational studies comparing the frequencies of HLA-A2 between vitiligo individuals and controls during 1966-2005. METHODS: The summary odds ratio (OR) was calculated by using a fixed- or a random-effects model. Meta-regression analysis was undertaken to investigate the effects of study characteristics on the pooled OR. RESULTS: Eleven case-controlled studies fulfilled our inclusion criteria. The studies identified a total of 777 patients and 4820 controls. Meta-analysis showed a significantly increased frequency of HLA-A2 in vitiligo among cases [OR = 2.07, 95% confidence interval (CI) 1.67-2.58]. Heterogeneity was explained by the quality of the study and the ethnic background of the participants. Meta-regression analysis further showed that the percentage of familial vitiligo among the subjects had a significant effect on the pooled OR (P = 0.008). No study had a significant effect on the pooled OR and no publication bias presented in the studies analysed (P = 0.688). CONCLUSION: These findings strongly suggest an association between HLA-A2 and vitiligo.     

X-linked hypophosphatemia in adults: prevalence of skeletal radiographic and scintigraphic features

The radiologic studies of 38 essentially untreated adults with X-linked hypophosphatemia (XLH) were reviewed to determine the prevalence of radiologic features, to compare the findings in men and in women, and to elucidate the natural history of the disease by comparing the findings in young, intermediate-age, and older patients. Bone-reinforcement lines were common, but no characteristic mineral mass alteration was established. Looser zones were more prevalent in older subjects. Osteoarthritis was common, occurring in the ankles, knees, feet, sacroiliac joints, and wrists. Enthesopathy was infrequent in the younger group but was present in every member of the intermediate and older groups and was often accompanied by extra ossicles. Curvatures of the lower-extremity long bones were common in all age groups. Three new skeletal alterations in XLH were found to be common: flaring of the iliac wings, trapezoidal distal femoral condyles, and alterations in talar morphology, including shortening of the talar neck and flattening of the talar dome. Technetium-99m methylene diphosphonate scintigrams of 17 subjects were often abnormal, depicting bowing deformity and focal tracer accumulation in diaphyseal cortices and in periarticular and extraarticular regions. The mean metabolic index was moderately elevated (4.0). Both radiographic and scintigraphic findings were more severe in men, consistent with hemizygosity. The natural history of untreated XLH in both sexes is characterized by the development of a variety of age-related skeletal abnormalities during adulthood.