Field-based performance of three pre-market rapid hepatitis C virus antibody assays in STAHR (Study to Assess Hepatitis C Risk) among young adults who inject drugs in San Diego, CA.

BACKGROUND: Approximately 4.1 million Americans are estimated to have been infected with hepatitis C virus (HCV), 45-85% of whom are unaware of their infection. Persons who inject drugs (PWID) account for 55.8% of all persons with HCV antibody (anti-HCV) in the U.S. PWID have limited access to healthcare and are infrequently tested for anti-HCV using conventional laboratory assays. OBJECTIVE: To evaluate performance characteristics (sensitivity and specificity) of three, pre-market rapid point-of-care tests (one oral fluid and two finger-stick assays) from two manufacturers (Chembio and MedMira) in settings providing services to young adult PWID in San Diego, CA. STUDY DESIGN: Behavioral risk assessment surveys and testing for HCV were conducted among persons who reported injection drug use (IDU) within the past 6 months as part of the Study to Assess Hepatitis C Risk (STAHR) among PWID aged 18-40 years in 2009-2010. Sensitivity and specificity of the rapid anti-HCV assays were evaluated among STAHR participants, using two commonly used testing algorithms. RESULTS: Variability in sensitivity (76.6-97.1%) and specificity (99.0-100.0%) was found across assays. The highest sensitivity achieved for the Chembio finger-stick blood, Chembio oral fluid and MedMira finger-stick blood tests was 97.1%, 85.4% and 80.0% respectively; the highest specificity was 99.0%, 100.0% and 100.0%, respectively. In multivariate analysis false negative anti-HCV results were associated with female sex for the MedMira blood assay. CONCLUSIONS: Sensitive anti-HCV rapid assays are appropriate and feasible for high-prevalence, high-risk populations such as young PWID.

Hepatitis C testing practices and prevalence in a high-risk urban ambulatory care setting.

Approximately 3.2 million persons are chronically infected with the hepatitis C virus (HCV) in the U.S.; most are not aware of their infection. Our objectives were to examine HCV testing practices to determine which patient characteristics are associated with HCV testing and positivity, and to estimate the prevalence of HCV infection in a high-risk urban population. The study subjects were all patients included in the baseline phase of the Hepatitis C Assessment and Testing Project (HepCAT), a serial cross-sectional study of HCV screening strategies. We examined all patients with a clinic visit to Montefiore Medical Center from 1/1/08 to 2/29/08. Demographic information, laboratory data and ICD-9 diagnostic codes from 3/1/97-2/29/08 were extracted from the electronic medical record. Risk factors for HCV were defined based on birth date, ICD-9 codes and laboratory data. The prevalence of HCV infection was estimated assuming that untested subjects would test positive at the same rate as tested subjects, based on risk-factors. Of 9579 subjects examined, 3803 (39.7%) had been tested for HCV and 438 (11.5%) were positive. The overall prevalence of HCV infection was estimated to be 7.7%. Risk factors associated with being tested and anti-HCV positivity included: born in the high-prevalence birth-cohort (1945-64), substance abuse, HIV infection, alcohol abuse, diagnosis of cirrhosis, end-stage renal disease, and alanine transaminase elevation. In a high-risk urban population, a significant proportion of patients were tested for HCV and the prevalence of HCV infection was high. Physicians appear to use a risk-based screening strategy to identify HCV infection.

Community-based hepatitis B screening programs in the United States in 2008.

The Centers for Disease Control and Prevention (CDC) recommends hepatitis B surface antigen (HBsAg) testing to identify hepatitis B virus (HBV) infection for foreign-born persons from areas with HBsAg prevalence of > or = 2%. Currently, most HBsAg screening in the United States is performed by independent community organizations. For these HBsAg screening programs, we collected information about the location, number of people screened, other services beyond screening provided, the population/ethnicity groups targeted for screening, and the prevalence of HBsAg among those screened. We identified programs offering screening by contacting programs known to us, from interviews with identified programs, and from structured Internet searches, and collected information using a simple e-mail survey with follow-up phone calls. We identified 55 possible community HBsAg screening programs, of which we successfully contacted 31 programs. In the past year, contacted programs screened an estimated 21 817 patients with an 8.1% average HBsAg prevalence. The majority of programs screened persons born in Asia and their children, and a small number of programs screened persons from Africa or Eastern Europe; very few programs screened U.S.-born persons at risk of HBV infection due to behavioural factors. We identified few or no programs in the American Southeast, the Midwest, and the Southwest outside of California and the Houston area. The HBsAg screening programs that we contacted were effective in identifying and screening patients at risk of HBV as evidenced by the high prevalence observed among those screened. However, their efforts alone are likely insufficient to meet the need for screening recommended by CDC.

Hepatitis B vaccination rate of homeless children in Baltimore.

OBJECTIVE: To investigate the hepatitis B vaccination rate in homeless children 2 to 18 years old living in Baltimore City. METHODS: During a 21-month period, 250 children from homeless shelters were enrolled. RESULTS: The percent of children who had received 3 or more doses of hepatitis B vaccine was inversely related to age; 90% in 2- to 5-year-olds and 29% in 13- to 18-year-olds (P<0.0001). Seventy percent of 2- to 5-year-olds had at least some of their vaccine history recorded in the Baltimore Immunization Registry Program but the history was complete in only half. Forty-two percent of 13- to 18-year-olds had no hepatitis B vaccine doses recorded in any source; 49 per cent of 10- to 18-year-olds were either not immunized or had received only one hepatitis B vaccine dose. CONCLUSIONS: Hepatitis B vaccine coverage is high in homeless children up to 9 years of age, whereas the majority of homeless children 10 years of age and older are unprotected against hepatitis B virus infection. Tracking the vaccine records in homeless children is labor intensive. Better public health strategies to deliver hepatitis B vaccine to older homeless children are urgently needed.

Lysine(164)alpha of protein farnesyltransferase is important for both CaaX substrate binding and catalysis.

Protein farnesyltransferase (FTase) catalyses the formation of a thioether linkage between proteins containing a C-terminal CaaX motif and a 15-carbon isoprenoid. The involvement of substrates such as oncogenic Ras proteins in tumour formation has led to intense efforts in targeting this enzyme for development of therapeutics. In an ongoing programme to elucidate the mechanism of catalysis by FTase, specific residues of the enzyme identified in structural studies as potentially important in substrate binding and catalysis are being targeted for mutagenesis. In the present study, the role of the positive charge of Lys(164) of the alpha subunit of FTase in substrate binding and catalysis was investigated. Comparison of the wild-type enzyme with enzymes that have either an arginine or alanine residue substituted at this position revealed unexpected roles for this residue in both substrate binding and catalysis. Removal of the positive charge had a significant effect on the association rate constant and the binding affinity of a CaaX peptide substrate, indicating that the positive charge of Lys(164)alpha is involved in formation of the enzyme (E).farnesyl diphosphate (FPP).peptide ternary complex. Furthermore, mutation of Lys(164)alpha resulted in a substantial decrease in the observed rate constant for product formation without alteration of the chemical mechanism. These and additional studies provide compelling evidence that both the charge on Lys(164)alpha, as well as the positioning of the charge, are important for overall catalysis by FTase.

Synthesis and evaluation of GGPP geometric isomers: divergent substrate specificities of FTase and GGTase I.

A stereocontrolled synthetic route has been used to prepare two of the geometric isomers of all-trans-GGPP. Neither of these isomers is effective substrates for mammalian GGTase I, but 3 is a potent inhibitor of this enzyme (IC(50)=100 nM). Surprisingly, both compounds are effective substrates for mammalian FTase.

Grignard-mediated synthesis and preliminary biological evaluation of novel 3-substituted farnesyl diphosphate analogues.

A series of substituents was installed at the 3 position of farnesyl diphosphate through a copper-cyanide mediated coupling of a vinyl triflate with various Grignard reagents. These novel FPP mimetics were then evaluated as inhibitors of or substrates for mammalian protein farnesyl transferase. The IC50 values for these compounds range from 18 to 10,100 nm, with the 3-isopropenyl analogue being one of the most potent FPP-mimetic mFTase inhibitors yet synthesized.

The epidemiology of tuberculosis in the United States.

After a dramatic increase in the incidence of TB in the United States from 1985 to 1992, the epidemiology of TB changed, with both the number of cases and the incidence of TB decreasing since 1992. The decreases have been focal, however, affecting only certain geographic areas (e.g., New York, California, and New Jersey) and certain populations (e.g., 25-44 year age group and people born in the United States). The factors responsible for the decrease in those areas and populations are multiple but the most important are thought to be improvements in TB control and treatment programs in communities serving populations at greatest risk for TB. Despite the overall decline in TB cases, the numbers of foreign-born people with TB continue to increase. Factors contributing to the increase in TB among foreign-born people include the prevalence of TB in the country of origin, duration of residence in the United States after immigration, inadequate screening for or treatment of TB before entering the United States, and inadequate follow-up of those who have entered the United States with noninfectious TB (i.e., abnormal chest radiograph with negative sputum smears). Control of TB among the foreign-born population is essential if the current downward trend in reported TB cases in the United States is to be maintained. The HIV epidemic had a significant impact on the increase in TB incidence in the United States in the late 1980s but improvements in measures to control transmission of TB appear to have been effective in reversing that trend. The current national decrease trend in TB morbidity can be sustained through organized efforts by federal and private agencies and state and local health departments to ensure that all people with TB are identified and treated promptly. Such efforts must be aimed at areas and populations identified as high risk for TB, especially foreign-born people and people who are infected with HIV.