The origin of finches on Tristan da Cunha and Gough Island, central South Atlantic ocean.

The Nesospiza finches of the Tristan da Cunha archipelago and Rowettia goughensis from Gough Island, 380 km distant, are both derived from tanager-finches (Thraupidae) that colonized the islands by crossing more than 3000 km of ocean from South America. Sequences from two mitochondrial and four nuclear genes indicate that the Patagonian bridled finches Melanodera are the closest relatives of the South Atlantic finches. Melanodera typically was sister to Rowettia, although some genes linked it more closely to Nesospiza. There was no evidence that Rowettia and Nesospiza are sister taxa, suggesting that the South Atlantic finches evolved from separate colonization events, as apparently was the case for moorhens Gallinula spp. at the two island groups. Genetic divergence between the two island finch genera thus provides an estimate of the maximum period of time they have been present at the islands, some 3-5 million years. A brief review of colonization histories suggests that island hopping by passerine birds is infrequent among islands more than 100-200 km apart.

A review of the one-year incidence of resistance to lamivudine in the treatment of chronic hepatitis B : Lamivudine resistance.

PURPOSE: The development of antiviral resistance is a recognized challenge to successful treatment of chronic hepatitis B (CHB), but it has been difficult to establish an accurate estimate of its incidence due to a number of factors: (a) lack of an accepted definition of antiviral resistance; (b) lack of a standardized assay to assess resistance; and (c) lack of consensus on patient selection criteria for resistance testing. Lamivudine, an effective and well-established antiviral agent, has been reported to show one-year resistance rates in CHB ranging from 6% to 32%, but methodologies used to calculate these rates vary considerably. This article reviews the clinical, statistical, and laboratory methodologies of clinical studies reporting one-year rates of antiviral resistance to lamivudine in CHB. METHODS: Studies reporting one-year resistance rates to lamivudine in CHB were analyzed for methodologic differences and their influence on reported resistance rates. RESULTS: Studies using only a genotypic definition of resistance reported one-year rates ranging from 14% to 32%. Studies assessing genotypic resistance in patients with evidence of virologic breakthrough reported much lower one-year resistance rates of 6.4-15.4%. CONCLUSIONS: It is important when comparing resistance rates to antiviral drugs in CHB to consider the methodology and definition of resistance used because this can dramatically influence the results.

A double-blind randomized trial of adefovir dipivoxil in Chinese subjects with HBeAg-positive chronic hepatitis B.

Four hundred and eighty Chinese subjects with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) were enrolled in a multicenter, double-blind, randomized, placebo-controlled study of adefovir dipivoxil (ADV) 10 mg once daily. There was a significant difference in reduction of serum hepatitis B virus (HBV) DNA after 12 weeks between subjects who received ADV and those who received the placebo (3.4 and 0.1 log10 copies/mL, respectively, P < .001). Further reductions in serum HBV DNA and increases in the proportion of subjects with an HBV DNA level of at most 10(5) copies/mL, with HBV DNA undetectable, and with ALT normalization were observed in ADV-treated subjects at week 52 (median HBV DNA reduction of 4.5 log(10) copies/mL, 67% with HBV DNA