ABSTRACT:Raltegravir is a potent human immunodeficiency virus 1 (HIV-1) integrase strand transfer inhibitor that is being developed as a novel anti-AIDS drug. The absorption, metabolism, and excretion of raltegravir were studied in healthy volunteers after a single oral dose of 200 mg (200 Ci) of [ 14 C]raltegravir. Plasma, urine, and fecal samples were collected at specified intervals up to 240 h postdose, and the samples were analyzed for total radioactivity, parent compound, and metabolites. Radioactivity was eliminated in substantial amounts in both urine (32%) and feces (51%). The elimination of radioactivity was rapid, since the majority of the recovered dose was attributable to samples collected through 24 h. In extracts of urine, two components were detected and were identified as raltegravir and the glucuronide of raltegravir (M2), and each accounted for 9% and 23% of the dose recovered in urine, respectively. Only a single radioactive peak, which was identified as raltegravir, was detected in fecal extracts; raltegravir in feces is believed to be derived, at least in part, from the hydrolysis of M2 secreted in bile, as demonstrated in rats. The major entity in plasma was raltegravir, which represented 70% of the total radioactivity, with the remaining radioactivity accounted for by M2. Studies using cDNA-expressed UDP-glucuronosyltransferases (UGTs), form-selective chemical inhibitors, and correlation analysis indicated that UGT1A1 was the main UGT isoform responsible for the formation of M2. Collectively, the data indicate that the major mechanism of clearance of raltegravir in humans is UGT1A1-mediated glucuronidation.HIV-1 is the etiologic agent of AIDS. HIV infection continues to be a major problem with more than 40 million individuals currently infected with the virus worldwide ([UNAIDS] Joint United Nations Programme on HIV/AIDS 2006 Report on the global AIDS epidemic. http://www.unaids.org). The current standard of care for treating HIV infection, called HAART, is a regimen typically consisting of three or more drugs from two or more available classes. Current HAART medications (of which there are Ͼ20) include members from four classes of drugs: nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, protease inhibitors, and fusion inhibitors. Although the advent of HAART has significantly reduced AIDS-related morbidity and mortality, it has been estimated that 78% of treatment-naive patients harbor viruses that are resistant to one or more of the three classes (nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, and protease inhibitors) (Richman, 2001;Little et al., 2002). Because of this factor and issues of tolerability, toxicity, and patient noncompliance due to the rigorous drug administration schedules, there is a critical need for new HIV therapies capable of addressing the deficiencies inherent with currently used drugs.Integrase is one of the three HIV-1 enzymes required for viral replication (Esposito and Cr...

A number of issues have remained unanswered in the design of "thorough QT"(TQT) studies. In this randomized, placebo-controlled, two-period crossover study in 20 healthy subjects, replicate electrocardiograms (ECGs) were recorded on a digital 12-lead Holter recorder, extracted in a core ECG laboratory, and interpreted manually by a cardiologist. The observed within-subject variability was slightly greater when time-matched baselines were employed than when predose baselines were employed, whereas the magnitude of the increase in QTc was similar for both. Moxifloxacin 400 mg was associated with an observed 7.5-12.5 ms increase in the mean placebo- and baseline-corrected QTc interval. A PK-QTc model estimated a 3.9 ms increase in the QTc interval for every 1,000 ng/ml increase in moxifloxacin concentration. The QTc increases associated with moxifloxacin support the appropriateness of its use as a positive control in TQT studies. This crossover study failed to justify the use of time-matched baselines rather than the less resource-intensive predose definition of baseline.

In the present study, rat cardiac myocytes were used as an in vitro ischemia/reperfusion injury model to delineate the role of c-Jun N-terminal kinase (JNK) 1 and JNK2 isoforms in ischemia/reoxygenation-induced apoptosis using an antisense approach. Exposure of rat cardiac myocytes to ischemia did not induce apoptosis as detected by staining with either acridine orange/ethidium bromide or annexin-V-fluorescein/propidium iodide. In contrast, a time-dependent increase in the number of apoptotic cells was noted after reoxygenation of ischemic myocytes, whereas the level of necrotic cells remained unaltered. Reoxygenation, but not ischemia alone, also caused a time-dependent increase in JNK activation that preceded apoptosis induction. Treatment of cardiac myocytes with antisense (AS) oligonucleotides that specifically targeted either JNK1 or JNK2 significantly reduced both mRNA and protein expression of the target isoform but had no effect on the expression of the alternate isoform. Pretreatment of cardiac myocytes with JNK1 AS, but not JNK2 AS, resulted in almost complete attenuation of reoxygenation-induced apoptosis. Furthermore, control oligonucleotides for JNK1 AS or JNK2 AS had no effect on JNK mRNA or protein expression or reoxygenation-induced apoptosis, indicating a sequence-specific mode of action. Additional studies revealed that apoptosis induced by other JNK-activating stimuli, including ceramide, heat shock, and UV irradiation, was partly suppressed after treatment with JNK1 AS but not JNK2 AS. These findings demonstrate that the JNK1 isoform plays a preferential role in apoptosis induced by ischemia/reoxygenation as well as diverse JNK-activating cellular stresses.

Human autosomal dominant polycystic kidney disease (ADPKD) epithelia were grown in primary monolayer cultures and their properties compared with intact kidney epithelial cultures derived from individually microdissected normal human kidney proximal convoluted tubules (PCT), proximal straight tubules (PST), and cortical collecting tubules (CCT). In vivo, ADPKD cyst epithelia exhibited a thickened basement membrane, and immunofluorescence demonstrated the presence of laminin, fibronectin, type IV collagen, and heparan sulfate proteoglycan in basement membranes and type I collagen in the interstitium. ADPKD epithelia grown in culture synthesized and secreted basally a unique, extracellular matrix that took the form of proteinaceous spheroids when the cells were grown on dried, type I collagen. Incorporation of H2[S35O4] into basement membrane extracts was increased more than ten-fold in ADPKD epithelia by comparison to normal PST and CCT. In addition to incorporation into the normal tubular basement membrane 220 kD band, radioactivity was also seen at 175 kD and 150 kD in ADPKD extracts. Growth in culture of cyst-lining ADPKD epithelia was more rapid than normal tubules, and was abnormal since there was no absolute requirement for added extracellular matrix. However, when ADPKD epithelia were grown on different, exogenous matrix protein components, a profound influence on both structure and epithelial cell proliferation was seen. Growth on a complete basement membrane three-dimensional gel derived from the Engelbreth-Holm-Swarm (EHS) sarcoma led to a reduction in the numbers of spheroids and increase in amorphous filaments. Incorporation of [3H]-thymidine into ADPKD epithelia was greater than into normal PCT, PST, and CCT and was also greatly modified by the type of extracellular matrix components provided. In studies using single matrix components, the strongest proliferative response was seen when ADPKD epithelia were plated on type I collagen greater than type IV collagen greater than fibronectin greater than laminin. These findings suggest that the excessive growth of cyst-lining epithelia may be, at least in part, a result of abnormal basement membrane and extracellular matrix production by ADPKD cells.

Hydrogen peroxide (H2O2) may incite cardiac ischemia-reperfusion injury. We evaluate herein the influence of H2O2-induced oxidative stress on heart muscle hexose metabolism in cultured neonatal rat cardiomyocytes, which have a substrate preference for carbohydrate. Cardiomyocyte exposure to 50 microM-1.0 mM bolus H2O2 transiently activated the pentose phosphate cycle and thereafter inhibited cellular glucose oxidation and glycolysis. These metabolic derangements were nonperoxidative in nature (as assessed in alpha-tocopherol-loaded cells) and occurred without acute change in cardiomyocyte hexose transport or glucose/glycogen reserves. Glycolytic inhibition was supported by the rapid, specific inactivation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The degree of GAPDH inhibition correlated directly with the magnitude of the oxidative insult and was independent of both metal-catalyzed H2O2 reduction to free radicals and lipid peroxidation. Severe GAPDH inhibition was required for a rate-limiting effect on glycolytic flux. Cardiomyocyte pyruvate dehydrogenase was also inhibited by H2O2 overload, but to a lesser degree than GAPDH such that entry of hexose-derived acetyl units into the tricarboxylic acid cycle was not as restrictive as GAPDH inactivation to glycolytic ATP production. An increase in phosphofructokinase activity accompanied GAPDH inactivation, leading to the production and accumulation of glycolytic sugar phosphates at the expense of ATP equivalents. Cardiomyocyte treatment with iodoacetate or 2-deoxyglucose indicated that GAPDH inactivation/glycolytic blockade could account for approximately 50% of the maximal ATP loss following H2O2 overload. Partial restoration of GAPDH activity after a brief H2O2 "pulse" afforded some ATP recovery. These data establish that specific aspects of heart muscle hexose catabolism are H2O2-sensitive injury targets. The biochemical pathology of H2O2 overload on cardiomyocyte carbohydrate metabolism has implications for post-ischemic cardiac bioenergetics and function.

The glutamatergic system is thought to contribute to the motor disturbances observed in Parkinson's disease. Blockade of glutamatergic activity by a selective antagonist of the NR2B subunit of the N-methyl-D-aspartate (NMDA) receptor is associated with improvement in motor symptoms in a preclinical model of Parkinson's disease. A randomized, double-blind, double-dummy, placebo-controlled, 3-period crossover study was conducted in patients with moderate Parkinson's disease to evaluate the pharmacologic activity of MK-0657, an NR2B-selective NMDA receptor antagonist. Patients (n=16) received single oral doses of MK-0657 7 mg, carbidopa/levodopa 25/250 mg (LD) as a positive control, and placebo, after which motor function was serially evaluated by means of the Unified Parkinson's Disease Rating Scale-Motor Examination (UPDRS-ME). LD administration resulted in significant improvement in the UPDRS-ME relative to placebo (P=.025), confirming the sensitivity of the test paradigm; however, the UPDRS-ME change following MK-0657 administration showed no improvement compared with placebo (P=.110) despite exceeding the target MK-0657 plasma concentration of 400 nM. Although the administration of MK-0657 was generally well tolerated, it was associated with increases in systolic and diastolic blood pressure relative to placebo. The results of this study do not support ongoing clinical development of MK-0657 as a novel monotherapy for Parkinson's disease.

Oxidative stress induced by hydrogen peroxide (H2O2) may contribute to the pathogenesis of ischemic-reperfusion injury in the heart. For the purpose of investigating directly the injury potential of H2O2 on heart muscle, a cellular model of H2O2-induced myocardial oxidative stress was developed. This model employed primary monolayer cultures of intact, beating neonatal-rat cardiomyocytes and discrete concentrations of reagent H2O2 in defined, supplement-free culture medium. Cardiomyocytes challenged with H2O2 readily metabolized it such that the culture content of H2O2 diminished over time, but was not depleted. The consequent H2O2-induced oxidative stress caused lethal sarcolemmal disruption (as measured by lactate dehydrogenase release), and cardiomyocyte integrity could be preserved by catalase. During oxidative stress, a spectrum of cellular derangements developed, including membrane phospholipid peroxidation, thiol oxidation, consumption of the major chain-breaking membrane antiperoxidant (alpha-tocopherol), and ATP loss. No net change in the protein or phospholipid contents of cardiomyocyte membranes accompanied H2O2-induced oxidative stress, but an increased turnover of these membrane constituents occurred in response to H2O2. Development of lethal cardiomyocyte injury during H2O2-induced oxidative stress did not require the presence of H2O2 itself; a brief "pulse" exposure of the cardiomyocytes to H2O2 was sufficient to incite the pathogenic mechanism leading to cell disruption. Cardiomyocyte disruption was dependent upon an intracellular source of redox-active iron and the iron-dependent transformation of internalized H2O2 into products (e.g., the hydroxyl radical) capable of initiating lipid peroxidation, since iron chelators and hydroxyl-radical scavengers were cytoprotective. The accelerated turnover of cardiomyocyte-membrane protein and phospholipid was inhibited by antiperoxidants, suggesting that the turnover reflected molecular repair of oxidized membrane constitutents. Likewise, the consumption of alpha-tocopherol and the oxidation of cellular thiols appeared to be epiphenomena of peroxidation. Antiperoxidant interventions coordinately abolished both H2O2-induced lipid peroxidation and sarcolemmal disruption, demonstrating that an intimate pathogenic relationship exists between sarcolemmal peroxidation and lethal compromise of cardiomyocyte integrity in response to H2O2-induced oxidative stress. Although sarcolemmal peroxidation was causally related to cardiomyocyte disruption during H2O2-induced oxidative stress, a nonperoxidative route of H2O2 cytotoxicity was also identified, which was expressed in the complete absence of cardiomyocyte-membrane peroxidation. The latter mode of H2O2-induced cardiomyocyte injury involved ATP loss such that membrane peroxidation and cardiomyocyte disruption on the one hand and cellular de-energization on the other could be completely dissociated.(ABSTRACT TRUNCATED AT 400 WORDS)

therapy vectormediated expression of insulin-like growth factors protects cardiomyocytes from apoptosis and enhances neovascularization.