BACKGROUND Ovarian failure is a common toxic effect of chemotherapy. Studies of the use of gonadotropin-releasing hormone (GnRH) agonists to protect ovarian function have shown mixed results and lack data on pregnancy outcomes. METHODS We randomly assigned 257 premenopausal women with operable hormone-receptor–negative breast cancer to receive standard chemotherapy with the GnRH agonist goserelin (goserelin group) or standard chemotherapy without goserelin (chemotherapy-alone group). The primary study end point was the rate of ovarian failure at 2 years, with ovarian failure defined as the absence of menses in the preceding 6 months and levels of follicle-stimulating hormone (FSH) in the postmenopausal range. Rates were compared with the use of conditional logistic regression. Secondary end points included pregnancy outcomes and disease-free and overall survival. RESULTS At baseline, 218 patients were eligible and could be evaluated. Among 135 with complete primary end-point data, the ovarian failure rate was 8% in the goserelin group and 22% in the chemotherapy-alone group (odds ratio, 0.30; 95% confidence interval, 0.09 to 0.97; two-sided P = 0.04). Owing to missing primary end-point data, sensitivity analyses were performed, and the results were consistent with the main findings. Missing data did not differ according to treatment group or according to the stratification factors of age and planned chemotherapy regimen. Among the 218 patients who could be evaluated, pregnancy occurred in more women in the goserelin group than in the chemotherapy-alone group (21% vs. 11%, P=0.03); women in the goserelin group also had improved disease-free survival (P = 0.04) and overall survival (P=0.05). CONCLUSIONS Although missing data weaken interpretation of the findings, administration of goserelin with chemotherapy appeared to protect against ovarian failure, reducing the risk of early menopause and improving prospects for fertility. (Funded by the National Cancer Institute and others; POEMS/S0230 ClinicalTrials.gov number, NCT00068601.)

NDIVIDUALS WITH MODERATE TOsevere renal disease have an impaired ability to excrete phosphorus. As a result, they tend to develop hyperphosphatemia, especially in settings of high phosphorus intake. Elevated serum phosphorus levels are independently associated with increased mortality and morbidity. For example, serum phosphorus levels greater than the 5.5-mg/dL level recommended by practice guidelines are independently associated with a 20% to 40% increase in mortality risk among patients with end-stage renal disease (ESRD). [1][2][3][4][5][6][7][8][9] In addition, hyperphosphatemia appears to be involved in the development of atherosclerotic heart disease, secondary hyperparathyroidism, and bone disease among renal patients. [10][11][12] High phosphorus intake may also be detrimental for the general public. The dietary phosphorus intake of individuals in the United States has been in-creasing, while intake of calcium has been decreasing. 13 There is evidence to suggest that these intake patterns in-terfere with the normal process of calcium regulation and affect both peak bone mass and rate of bone loss, even See also Patient Page.

The helicase domain of hepatitis C virus NS3 (genotype 1b) was expressed in Escherichia coli and purified to homogeneity. The purified protein catalyzed the hydrolysis of nucleoside triphosphates (NTP) and the unwinding of duplex RNA in the presence of divalent metal ion. The enzyme was not selective for the NTP substrate. For example, UTP and acyclovir triphosphate were hydrolyzed efficiently by the enzyme. The rate of NTP hydrolysis was stimulated up to 27-fold by oligomeric nucleic acids (NA). Furthermore, NA bound to the enzyme with concomitant quenching of the intrinsic protein fluorescence. The dissociation constants of the enzyme for selected NA in the absence of NTP were between 10 and 35 M at pH 7.0 and 25°C. ؊1 ), respectively. These data were consistent with a random kinetic mechanism. Hepatitis C virus (HCV)1 is the principle agent responsible for non-A, non-B hepatitis (1, 2). Approximately 1% of the human population is infected with HCV. Standard interferon therapies are effective for some patients, but the majority do not clear the virus, resulting in relapse (3). Consequently, an urgent medical need for an effective antiviral agent exists.Development of an effective therapeutic agent has been hindered by the lack of reliable cell culture systems for propagating HCV. Consequently, efforts to characterize potential therapeutic agents have relied on surrogate expression systems and the techniques of molecular biology. For example, the NS3 protein of hepatitis C virus has several enzymatic activities necessary for viral replication that make it an attractive antiviral target. The N-terminal 20 kDa of NS3 is a serine proteinase that cleaves the HCV-encoded polyprotein at a minimum of four specific sites (4). The C-terminal 50 kDa of NS3 has NTPase (5) and RNA helicase activity (6). A detailed understanding of either of these enzymatic activities could facilitate identification of potent antiviral agents. Consequently, we have initiated a program to characterize the interaction of the HCV helicase domain with nucleoside triphosphates (NTP) and polymeric nucleic acids (NA). HCV helicase catalyzes the three reactions shown in Scheme I.dsNA ϩ NTP 3 ssNA ϩ NDP ϩ P i (c) SCHEME I. Reactions catalyzed by HCV helicase where NA is single stranded (ss) or double stranded (ds) polynucleic acid and NTP is a nucleoside triphosphate.The physiologically relevant reaction for viral replication is probably unwinding of double-stranded NA (reaction c). The kinetic studies presented herein, which represent the first comprehensive kinetic analysis of a RNA helicase, have focused on the NTPase activities of the HCV helicase in the presence or absence of NA (reactions a and b in Scheme I). We have chosen to work with HCV genotype 1b, which is a major subtype found in both the Japanese and American populations (7). In summary, we found that 1) the NTPase activity was nonselective for the nucleobase and sugar of the NTP substrate, 2) the NTPase activity was stimulated up to 25-fold by selected NA in a reaction that was rela...

Human immunodeficiency virus type 1 (HIV-1) Gag protease cleavage sites (CS) undergo sequence changes during the development of resistance to several protease inhibitors (PIs). We have analyzed the association of sequence variation at the p7/p1 and p1/p6 CS in conjunction with amprenavir (APV)-specific protease mutations following PI combination therapy with APV. Querying a central resistance data repository resulted in the detection of significant associations (P < 0.001) between the presence of APV protease signature mutations and Gag L449F (p1/p6 LP1F) and P453L (p1/p6 PP5L) CS changes. In population-based sequence analyses the I50V mutant was invariably linked to either L449F or P453L. Clonal analysis revealed that both CS mutations were never present in the same genome. Sequential plasma samples from one patient revealed a transition from I50V M46L P453L viruses at early time points to I50V M46I L449F viruses in later samples. Various combinations of the protease and Gag mutations were introduced into the HXB2 laboratory strain of HIV-1. In both single-and multiple-cycle assay systems and in the context of I50V, the L449F and P453L changes consistently increased the 50% inhibitory concentration of APV, while the CS changes alone had no measurable effect on inhibitor sensitivity. The decreased in vitro fitness of the I50V mutant was only partially improved by addition of either CS change (I50V M46I L449F mutant replicative capacity Ϸ 16% of that of wild-type virus). Western blot analysis of Pr55 Gag precursor cleavage products from infected-cell cultures indicated accumulation of uncleaved Gag p1-p6 in all I50V viruses without coexisting CS changes. Purified I50V protease catalyzed cleavage of decapeptides incorporating the L449F or P453L change 10-fold and 22-fold more efficiently than cleavage of the wild-type substrate, respectively. HIV-1 protease CS changes are selected during PI therapy and can have effects on both viral fitness and phenotypic resistance to PIs.