Screening for Hepatitis C in injecting drug users: a cost utility analysis

BACKGROUND: Hepatitis C is a major public health problem of increasing importance among injecting drug users, among whom screening has been proposed. We therefore estimated the cost utility of screening for hepatitis C infection among people with a history of injecting drug use in contact with drug misuse services. METHODS: A spreadsheet-based model of screening using ELISA followed by polymerase chain reaction tests and treatment using combination therapy with interferon alpha and ribavirin was developed. Parameters were informed by literature review, expert opinion and a survey of current screening practice in England. A range of one-way sensitivity analyses were carried out to explore uncertainty in the results for cost effectiveness. RESULTS: Screening for HCV is likely to yield benefits in the population concerned at around 28,000 pounds per quality adjusted life year. This estimate is reasonably stable when explored in extensive one-way sensitivity analysis but appeared sensitive to the proportion of HCV positive people who accept biopsy or treatment and the utility gains associated with successful drug treatment. Important other areas of uncertainty include the effects of mortality from other causes on the cost effectiveness of screening in this population and the time at which symptoms would have led to presentation in the absence of a screening programme. CONCLUSION: Screening for HCV in this population is moderately cost effective, although some caution must remain in accepting this estimate given the current uncertainties in this field, and further research is required.     

Prolonged survival after complete resection of metastases from intraocular melanoma

BACKGROUND: The median survival time is only 2-6 months after a diagnosis of metastases from intraocular melanoma. Because complete resection of metastatic melanoma from a cutaneous primary tumor can prolong survival, the authors hypothesized that resection also might benefit patients with metastases from an intraocular site. METHODS: From 1971 to 1999, 112 patients with metastatic melanoma from an intraocular site were enrolled in various treatment protocols after informed consent was obtained. Prospectively recorded clinical variables and follow-up information were retrieved from the patient database. Survival curves were estimated using the Kaplan-Meier method. Univariate analysis was performed with the log-rank test. Multivariate analysis was performed using the Cox proportional hazards regression model. Propensity score analysis was used to reduce the imbalance between subgroups and to assess treatment effect. RESULTS: Seventy-eight patients (70%) presented with liver involvement. Twenty-four patients (21%) underwent resection of metastatic lesions. At a median follow-up time of 11 months (range, 1-97 months; > 36 months for survivors), the median survival period was 11 months and the 5-year survival rate was 7%. Univariate analysis showed that surgical resection, site of metastases, number of metastatic lesions, and disease-free interval were correlated significantly with survival (P < 0.001, P < 0.001, P < 0.001, and P = 0.031, respectively). Multivariate analysis showed that surgical resection was significant (P = 0.008) but that the site of metastases was not (P = 0.146). The median survival and the 5-year survival rate were 38 months and 39%, respectively, for surgical patients, versus 9 months and 0%, respectively, for nonsurgical patients. After adjusting for covariate imbalance by propensity score analysis, surgery remained significant (P = 0.021) on multivariate analysis. CONCLUSIONS: Complete resection may prolong survival in certain patients with distant metastases from intraocular primary melanoma. However, the overall unfavorable prognosis indicates an urgent need for more effective nonsurgical interventions.     

Allelic imbalance of 12q22-23 associated with APAF-1 locus correlates with poor disease outcome in cutaneous melanoma

Cutaneous melanoma is a highly aggressive tumor that is relatively resistant to chemotherapy and radiotherapy. This resistance may be in part due to inhibition of apoptosis. Apoptotic protease activating factor-1(APAF-1), a candidate tumor suppressor gene, mediates p53-induced apoptosis, and its loss promotes oncogenic transformation. To determine whether loss of the APAF-1 locus influences tumor progression, we assessed loss of heterozygosity microsatellites on the APAF-1 locus (12q22-23) in 62 primary and 112 metastatic melanomas. We discovered that frequency of allelic imbalance was significantly higher in metastatic tumors (n = 36 of 98; 37%) than in primary melanomas (n = 10 of 54; 19%; P = 0.02). In metastatic melanomas, APAF-1 loss significantly correlated with a worse prognosis (P < 0.05) in the patients, and its loss during melanoma tumor progression suggests that APAF-1 is a tumor suppressor gene. Furthermore, loss of heterozygosity was frequent in the 12q22-23 chromosome region centromeric to the APAF-1 locus suggesting that other tumor-related genes may be present in the 12q22-23 region. In summary, the study demonstrates that allelic imbalance in the 12q22-23 region is a genomic surrogate of poor disease outcome for cutaneous melanoma patients.     

Choice of cardiac tissue plays an important role in the evaluation of drug-induced prolongation of the QT interval in vitro in rabbit

INTRODUCTION: Regulatory guidelines (CPMP/986/96, ICHS7B) recommend the use of isolated cardiac tissues, including Purkinje fibers, papillary muscles and ventricular trabeculae, for detecting potential drug-induced long QT. However, the differential sensitivity of these tissues in experimental drug-induced long QT is relatively unknown. We investigated the electrophysiological characteristics of these tissue types in vitro together with their different responses to drugs that are known to induce prolongation of the QT interval in man. METHODS: Electrophysiological parameters were measured in vitro using a micro-electrode technique. The isolated rabbit Purkinje fibers, papillary muscles or ventricular trabeculae were superperfused with Tyrode's solution and stimulated according to different stimulation protocols. The effects of dofetilide (1 x 10(-8) M), sertindole (1 x 10(-6) M), erythromycin (3 x 10(-4) M) and sparfloxacin (1 x 10(-4) M) were evaluated relative to solvent (n=8 to 12 for each group). RESULTS: In isolated Purkinje fibers, action potential duration at 90% repolarization (APD(90) at 1 Hz) was markedly prolonged by 55% (erythromycin), 103% (dofetilide), 118% (sertindole) and 88% (sparfloxacin) from baseline. The prolongation of APD(90) caused by these 4 compounds was associated with a 28% to 78% incidence of early afterdepolarizations (EADs) at 0.2 Hz only in the Purkinje fiber. In contrast, APD(90) was altered by erythromycin, dofetilide, sertindole and sparfloxacin only by +15%, +6%, -7% or +15%, respectively, in isolated papillary muscles, and by 33%, +28%, +4% or +16%, respectively, in ventricular trabeculae. EADs were not induced by these four compounds in papillary muscles or in trabeculae. Reducing the stimulation rate to 0.2 Hz resulted in a 33% prolongation of APD(90) in Purkinje fibers, while APD(90) was shortened by 10% in papillary muscles and by 20% in ventricular trabeculae. CONCLUSION: The present study demonstrates that the differential sensitivity of tissue types play an important role in the detection of drug-induced long APD and EADs. Indeed the Purkinje fiber was the only tissue type to display the well known phenomenon associated with I(kr) channel blockade (inverse-use dependence), when the stimulation rate was decreased below 1 Hz. Rabbit Purkinje fibers constitute the most sensitive tissue type for detecting drug-induced long action potential duration and EADs. As such the selection of tissue type needs to be taken into careful consideration in cardiac safety assessments when exploring drug induced long QT.     

Genome-wide screen identifies genes whose inactivation confer resistance to cisplatin in Saccharomyces cerevisiae

To identify novel genes that mediate cellular resistance to cisplatin, we have screened the collection of Saccharomyces cerevisiae deletion strains. We have found reproducibly 22 genes/open reading frames (ORF), which when deleted, confer resistance to cisplatin at a concentration that is lethal to wild-type cells. Complementation of individual deletion strains with the corresponding wild-type gene abolished cisplatin resistance, confirming that specific gene deletions caused the resistance. Twenty of the genes/ORFs identified have not been previously linked to cisplatin resistance and belong to several distinct functional groups. Major functional groups encode proteins involved in nucleotide metabolism, mRNA catabolism, RNA-polymerase-II-dependent gene regulation and vacuolar transport systems. In addition, proteins that function in ubiquitination, sphingolipid biogenesis, cyclic AMP-dependent signaling, DNA repair, and genome stability are also associated with cisplatin resistance. More than half of the identified genes are known to have sequences or functional homology to mammalian counterparts. Some deletion strains are cross-resistant to selected cytotoxic agents whereas hypersensitive to others. The sensitivity of certain resistant strains to other cytotoxic agents suggests that our findings may point to particular drug combinations that can overcome resistance caused by inactivation of specific genes.