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Biomedical subjects

N T Constantine

Publications and source records attributed to N T Constantine.

At least 19 recordsLinked to original sources
PubMed2001

Assessment of the performance of a rapid, lateral flow assay for the detection of antibodies to HIV.

Rapid HIV assays have recently been shown to have important applications for various testing situations, including early identification of infected individuals, to allow intervention strategies in a clinically relevant time frame. A rapid, lateral flow, HIV-1/2/O assay was evaluated using 2,000 serum or plasma samples from various risk groups and geographic locations, including HIV-1 and HIV-2 positive sera from five countries. Two U.S. Food and Drug Administration (FDA)-licensed screening assays and a FDA-licensed confirmatory assay were used as reference tests. The rapid assay exhibited a near-perfect sensitivity (99.2%) and an excellent specificity (99.9%). Moreover, its analytical sensitivity was found to be better than most FDA-licensed enzyme-linked immunosorbent assays (ELISAs), detecting infection at the same time as the most sensitive ELISA in two of five seroconversion panels, and at the same time or earlier than four of five ELISAs in all five panels. We conclude that this rapid assay is a suitable test for the detection of HIV infection that could be particularly useful in developing countries where facilities may not support the use of instrumentation.

AIDS Serodiagnosis↗
PubMed2001

The incidence of GB virus C / hepatitis G virus infection in Brazilian patients who received blood transfusion during cardiac surgery.

The incidence of GBV-C/hepatitis G virus (GBV-C/HGV) infection after blood transfusion is unknown in Brazil. Many studies have so far addressed its relationship with blood transfusion, but its association with liver disease was not confirmed. A prospective study was carried out between 1996 and 1999 in Rio de Janeiro. Ninety three patients who received blood transfusion during cardiac surgery were followed for six months and blood samples were drawn before and after surgery to determine antibodies to GBV-C/hepatitis G virus (anti-HGenv) using a step sandwich immunoassay and GBV-C/HGV-RNA using reverse transcriptase polymerase chain reaction. The alanine aminotransferase (ALT) levels were serially determined as well as clinical data compiled related to hepatitis. Prior to surgery, anti-HGenv was present in 35.5% (33/93) of patients and 4.3%(4/93) were found to be viremic. Seroconversion following transfusion was observed in 9 patients and 4 additional individuals became viremic for a total incidence of 23% (13/56). Six months after blood transfusion, only 4 of those nine patients previously antibody positive still had anti-HGenv detectable in serum. No patients had clinical or laboratory evidence of acute hepatitis and no correlation was found with GBV-C/HGV infection and number of blood units transfused (p = 0.37). This study highlights the importance of using both HGV-RNA PCR and anti-HGenv to accurately estimate the magnitude of GBV-C/HGV infection. The observed high prevalence and incidence rates show that this infection is common in Brazil; however, no clinical or biochemical evidence of liver disease was demonstrated in the period of study and longer longitudinal observation is needed to define any pathogenic effect.

Adolescent↗
PubMed2001

Prevalence of HIV-1 and oral lesions in pregnant women in rural Malawi.

OBJECTIVE: Whether oral lesions were associated with human immunodeficiency virus-type 1 (HIV-1) status in a cohort of pregnant Malawian women was studied. STUDY DESIGN: Six hundred thirty-eight women participated in a randomized prospective study at 3 prenatal clinics in a rural area of southern Malawi. Oral examinations, followed by collection of oral fluid specimens with an HIV-1 oral specimen collection device, were performed. The specimens were tested for antibodies against HIV-1. RESULTS: Sixty-one oral lesions were found in 60 participants. While traditional HIV-1 associated lesions were rare, benign migratory glossitis was unexpectedly common (6%). Oral hairy leukoplakia was significantly more common among women who were HIV-1 positive than among women who were HIV-1 negative. An HIV-1 prevalence rate of 21.8% was estimated among the women, with the highest rate of HIV-1 infection (34.1%) among women aged 25 to 29 years. CONCLUSION: Stratifying lesions showed a small number of oral hairy leukoplakia to be markers for HIV-1. A high seroprevalence was found in this rural cohort, but there were unexpectedly few oral lesions. The relatively few oral lesions diagnosed may indicate a recent infection with HIV.

Adult↗
PubMed2001

Fourth-generation enzyme-linked immunosorbent assay for the simultaneous detection of human immunodeficiency virus antigen and antibody.

The VIDAS HIV DUO Ultra, a fourth-generation immunoassay under development for the simultaneous detection of human immunodeficiency virus type 1 (HIV-1) p24 antigen and antibodies to HIV-1 and HIV-2, was evaluated. The enzyme-linked fluorescence immunoassay, performed on the automated VIDAS instrument, is claimed to detect early and established HIV infection. The assay was challenged with a total of 2,847 samples that included 74 members of 10 seroconversion panels, 9 p24 antigen-only-reactive members of a panel of group M clades, 503 consecutively collected samples from individuals seeking care in the University of Maryland Medical System, 1,010 samples from U.S. blood donors, 1,141 samples from patients in a high-incidence population in Trinidad, 83 samples from a clinic for sexually transmitted diseases in the Bahamas, 10 confirmed HIV-1 group O samples, and 16 confirmed HIV-2 samples from the Cote d'Ivoire. Reference tests were U.S. Food and Drug Administration-licensed HIV antibody screening, p24 antigen tests, HIV confirmatory assays, and the Roche Diagnostics Amplicor HIV-1 Monitor. The VIDAS HIV DUO Ultra demonstrated 100% sensitivity and 99.5% specificity overall, with a 99.7% specificity in low-risk individuals. The analytical sensitivity, as assessed by seroconversion panels and p24 antigen in samples, was equivalent to the sensitivity of the reference assays used to characterize these panels. The VIDAS HIV DUO Ultra is accurate, offers potential advantages over conventional HIV testing for time and cost savings, has walk-away capability, and correctly identifies both early and established HIV infections.

Enzyme-Linked Immunosorbent Assay↗
PubMed2001

Prevalence of HIV, hepatitis B, and hepatitis C in people with severe mental illness.

OBJECTIVES: This study assessed seroprevalence rates of HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) among individuals with severe mental illness. METHODS: Participants (n = 931) were patients undergoing inpatient or outpatient treatment in Connecticut, Maryland, New Hampshire, or North Carolina. RESULTS: The prevalence of HIV infection in this sample (3.1%) was approximately 8 times the estimated US population rate but lower than rates reported in previous studies of people with severe mental illness. Prevalence rates of HBV (23.4%) and HCV (19.6%) were approximately 5 and 11 times the overall estimated population rates for these infections, respectively. CONCLUSIONS: Elevated rates of HIV, HBV, and HCV were found. Of particular concern are the high rates of HCV infection, which are frequently undetected. Individuals with HCV infection commonly fail to receive appropriate treatment to limit liver damage and unknowingly may be a source of infection to others.

Adolescent↗
PubMed2000

Detection of Kaposi's sarcoma-associated herpesvirus in oral and genital secretions of Zimbabwean women.

Kaposi's sarcoma-associated herpesvirus (KSHV) in oral and genital secretions of women may be involved in horizontal and vertical transmission in endemic regions. Nested polymerase chain reaction assays were used to detect KSHV DNA sequences in one-third of oral, vaginal, and cervical specimens and in 42% of peripheral blood mononuclear cell (PBMC) specimens collected from 41 women infected with human immunodeficiency virus type 1 who had Kaposi's sarcoma (KS). KSHV DNA was not detected in specimens from 100 women without KS, 9 of whom were seropositive for KSHV. A positive association was observed between KSHV DNA detection in oral and genital mucosa, neither of which was associated with KSHV DNA detection in PBMC. These data suggest that KSHV replicates in preferred anatomic sites at levels independent of PBMC viremia. Detection of genital-tract KSHV only among relatively immunosuppressed women may provide an explanation for infrequent perinatal transmission of KSHV.

AIDS-Related Opportunistic Infections↗
PubMed2000

Specifics on the refinement and application of two serological assays for the detection of antibodies to HHV-8.

BACKGROUND: Serologic assays for the detection of antibodies to human herpesvirus type 8 (HHV-8) are important for epidemiological studies and to further investigate the proposed pathogenesis of the virus in cancer. Although a variety of assays are available, a lack of optimization and standardization makes their usefulness uncertain, and may be responsible for the controversy concerning the prevalence of infection. OBJECTIVES: To refine an indirect immunofluorescent assay (IFA) for the detection of latent antibodies and a recombinant ORF 65 ELISA for the detection of lytic antibodies in order to increase their ability to differentiate individuals at higher and lower risk for HHV-8 infection. STUDY DESIGN: Sera from Kaposi's sarcoma (KS) patients and blood donors (BDs) were used to modify assay parameters in an attempt to better discriminate between the two populations. Modifications included methods of substrate fixation, incubation times, sample dilution, and antigen/conjugate concentrations. RESULTS: Optimal modifications to the latent IFA included acetone fixation of substrate, and dilution of sera to 1:64 which enhanced detection of HHV-8 antibodies from 68 to 92% in the KS population. Similarly, successful refinement of the ORF 65 ELISA to increase the signal-to-noise ratio included the use of 88 ng of ORF 65 antigen per well and serum dilutions of 1:50. Optical density-to-cut-off ratios directly correlated with titers, thereby introducing a strategy to predict antibody concentrations. The ORF 65 ELISA and the latent IFA were both able to discriminate between the two populations but with different efficiencies. CONCLUSIONS: Although neither the latent IFA nor the ORF 65 ELISA produced perfect test indices, improvement in their performances was noted following the optimization strategies. The ELISA produced better detection of antibodies to the virus than the IFA and permitted prediction of sample titers, thus improving cost and time effectiveness.

Antibodies, Viral↗
PubMed1998

Hepatitis E virus infection in eastern India.

Most cases of enterically transmitted non-A, non-B hepatitis in India have so far been attributed to hepatitis E virus (HEV) infection. Most of the documented studies of hepatitis have focused on the incidence of this disease in northern, western, and south central India. A small seroprevalence study was conducted in the eastern Indian city of Patna to assess the degree of HEV infection among acute sporadic hepatitis cases. Forty-two percent (24 of 57) of the cases of acute sporadic hepatitis were positive for anti-HEV antibodies. Absence of any serologic markers of hepatitis A, B, or E in 58% (33 of 57) of the cases with symptoms of acute hepatitis suggest that there may be as yet unidentified enterically transmitted viruses in this area.

Adult↗
PubMed1997

Use of renal allografts from donors positive for hepatitis B core antibody confers minimal risk for subsequent development of clinical hepatitis B virus disease.

BACKGROUND: The risk associated with transplantation of renal allografts from hepatitis B virus core antibody-positive (HBcAb(+)), hepatitis B virus surface antigen-negative (HBsAg(-)) donors is not well defined. METHODS: Over 4 years, we performed 45 kidney transplants from IgG HBcAb(+), IgM HBcAb(-), HBsAg(-) donors into recipients with a history of prior hepatitis B virus (HBV) infection or reported vaccination. We examined HBV-related outcomes in these 45 patients, in comparison with 45 recipients of allografts from HBcAb(-) donors (matched for transplant type, date, and pretransplant HBV antibodies). We sought evidence for HBV transmission by testing posttransplant sera for the presence of HBcAb, hepatitis B virus surface antibody, and HBsAg. Additionally, we analyzed alanine aminotransferase profiles and allograft survival rates for all patients. RESULTS: No patient receiving an allograft from an HBcAb(+) donor developed clinical HBV infection. No patient receiving an allograft from an HBcAb(+) donor had HBsAg detected through retrospective testing of stored sera or through prospective routine clinical evaluation and care. However, among the HBcAb(+) kidney recipients, 27% developed new HBcAb and/or hepatitis B virus surface antibody after transplant; in contrast, only 4% of control patients developed new antibody responses (relative risk=4.94; confidence interval 1.07-22.83). Among the recipients of HBcAb(+) organs, 18% developed elevated transaminases after transplant, in comparison with 36% of the controls. No association was found between "seroconverter" status and elevated alanine aminotransferase profiles in either group. CONCLUSIONS: Transplantation of renal allografts from HBcAb(+), HBsAg(-) donors was not associated with clinically detectable HBV disease or antigenemia. However, recipients had a significantly increased risk of HBV seroconversion, consistent with exposure to HBV antigen. These results suggest that HBcAb(+) kidneys can be safely used if transplanted into appropriate recipients, but highlight the need for effective HBV vaccination and vaccine-response monitoring in potential recipients.

Adult↗
PubMed1997

Evaluation of two novel immunoassays designed to detect HIV antibodies in oral fluids.

The testing of oral fluid samples for the detection of HIV antibodies offers several advantages over the testing of blood. Our objective was to evaluate a new generation of rapid and simple assays designed specifically to detect HIV-1 and HIV-2 antibodies in oral fluids (saliva). Serum and oral fluid pairs were collected from 615 high- and low-risk individuals in the United States, Peru, and the ivory Coast. Two different oral fluid collection devices and rapid assay systems included: (1) the Orapette/SalivaCard HIV-1/ HIV-2 and (2) the Omni-Sal/ImmunoCcmb II HIV-1 and HIV-2. The corresponding serum pairs were analyzed by conventional ELISAs, and all reactive sera were confirmed with HIV-1 and HIV-2 Western blots. The results indicated a 100% sensitivity for both rapid oral fluid assays, including successful detection of HIV-2 antibodies. Specificities ranged from 99.8% to 100%. One sample produced a reactive result by the SalivaCard while being nonreactive by the other assays including the Western blots. Both assays performed excellently, indicating that antibodies to HIV can be detected reliably in oral fluids by simple and rapid assays. This combination of rapid testing technology and the use of easily collected oral fluid samples offers an efficient and accurate alternative to conventional testing and can be appropriately applied to a variety of testing situations for the laboratory diagnosis of HIV infection.

Blotting, Western↗
PubMed1997

Clinical applications of two detection systems for HIV using saliva.

The purpose of this research was to determine if the accuracy of HIV saliva and serum test results were influenced by changes in collection sites. In order to do so, serum and saliva samples were collected from 615 subjects in eight different geographic settings. The oral fluid collection/testing systems utilized were the Orapette SalivaCard HIV-1/HIV-2 antibody test (Trinity Biotech, Ireland) and the Omni-SAL/ImmunoComb II HIV 1 & 2 Saliva Test (Orgenics Ltd, Israel). For comparison, serum samples were tested by ELISA (Ortho) with reactive results confirmed via HIV-1 and HIV-2 Western blots (Biotech/Dupont, Institute Pasteur). The HIV serum and oral fluid collections were conducted in numerous test sites, which provided a great diversity in temperature, lighting and physical layout. The tests proved to be 99.8% and 100% specific, and both were 100% sensitive, regardless of the physical setting of the collections. While these systems are not currently available in the US, this study clearly demonstrates they can accurately be utilized in a variety of clinical settings, providing great promise for future applications.

AIDS Serodiagnosis↗
PubMed1996

Rapid and simple hepatitis assays: encouraging results from a blood donor population in Zimbabwe.

A rapid assay to detect antibodies to hepatitis C virus (HCV) in serum and two rapid/simple assays to detect hepatitis B surface antigen (HBsAg) in whole blood/serum were evaluated for their accuracy and suitability at the National Blood Transfusion Service, Harare, Zimbabwe. For this purpose, a total of 206 sera (196 routinely collected and 10 frozen) were tested using the HCV-SPOT (Genelabs Diagnostics), the SimpliRED HBsAg test (AGEN), and the Dipstick-HBsAg (PATH/Immuno-Chemical Laboratories). The results were compared with those obtained using a routine HBsAg enzyme immunoassay (EIA) (Auszyme, Abbott) and an HCV IgG second-generation EIA (Abbott). An HCV IgM test (Abbott) was used for samples that produced discordant results, and all HCV-reactive samples were confirmed using the INNO-LIA HCV Ab III synthetic peptide assay (Innogenetics). Overall, the concordance between the HCV-SPOT and the HCV EIA was 97.6% (201/206). For the 193 sera that were true HCV negatives, the number of false positives was six with the HCV-SPOT test, while the HCV EIA produced three (specificity = 97.0% and 98.5%, resp.). Of these false positives, two were so in both tests. None of the false positives contained IgM antibodies to HCV, and there were no false negatives in the two HCV tests. The concordance between the two rapid HBsAg tests and the HBsAg EIA was 99.5% (205/206). All the rapid/simple tests were easy to perform and interpret, required no (or minimal) laboratory equipment, and could be taught easily to local laboratory personnel. The cost of these tests is equivalent to or less than that of routine EIA methods.

Blood Donors↗
PubMed1995

Seroprevalence of human immunodeficiency virus, hepatitis B virus, hepatitis C virus, and rapid plasma reagin in a trauma population.

We evaluated the presence of human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), and rapid plasma reagin (RPR) among patients admitted to our trauma unit from April 15 to June 30, 1993. Of 984 patients tested, we found 255 (26%) had evidence of exposure to one or more of these agents: HIV, 4%; HBV, 20%; HCV, 14%; and RPR, 1%. Thirty-eight percent of patients had more than one positive serology, 75% of the HIV patients, 49% of the HBV patients, and 66% of the HCV patients. There was no difference between penetrating and nonpenetrating trauma with respect to any of the viruses. The risk factors for HIV-positive patients were non-White race, positive drug screen, positive alcohol screen, and city resident. Risk factors for HBV patients were non-White race, positive drug screen, and city resident. Risk factors for HBC patients were male sex, non-White race, positive alcohol screen, positive drug screen, and city resident. The risk of blood-borne infections in this group of patients is substantial.

Cross-Sectional Studies↗
PubMed1994

Successful use of two rapid HCV assays in a high prevalence Romanian population.

Hepatitis C virus (HCV) infection is of significant concern for recipients of blood and for patients who share resources such as hemodialysis machines. In many developing countries and in small peripheral laboratories, facilities and capabilities to perform ELISA assays may not be available. We evaluated two newly marketed rapid HCV serologic assays to determine their ability and suitability to detect antibodies to HCV in hemodialysis patients in Bucharest, Romania. Results indicated that both the Rapid HCV Ab assay (Clonatec, Paris, France) and the HCV-SPOT (Diagnostic Biotechnology, Singapore) detected HCV antibody in 23 of 27 patients. All 23 samples were also reactive by a routine HCV ELISA and were confirmed using a supplemental assay (HCV blot, Diagnostic Biotechnology, Singapore). Only one sample produced equivocal result by the Rapid HCV Ab assay. In this high prevalence population (90%), the use of recombinant or synthetic peptide rapid HCV assays has been successful in detecting confirmed positive cases of HCV and has shown excellent correlation with an ELISA screening assay. The tests are simple to perform, can be performed by individuals with minimal training, and have built-in quality control measures. We conclude that these tests may have important applicability in certain testing situations.

Enzyme-Linked Immunosorbent Assay↗
PubMed1994

Application of commercial assays to detect IgG antibodies to hepatitis C virus in urine: a pilot study from autopsy cases.

Hepatitis C virus (HCV), the main cause of non-A, non-B hepatitis in the United States and possibly in the world, is believed to be transmitted primarily through parenteral exposure. Many screening and supplemental tests are available to detect antibodies to HCV in serum. The ability to use commercial assays to detect antibodies to HCV in urine was investigated in this study. A total of 229 serum/urine matched samples were collected sequentially from forensic autopsy cases examined at the Office of the Chief Medical Examiner, State of Maryland. Testing was performed using the Ortho, Innogenetics, and Abbott second generation HCV screening tests and the INNO-LIA HCV Ab supplemental assay. Sample volumes were increased for urine testing. Forty-six of 229 serum samples were positive by screening and confirmed by supplemental tests. The urine samples produced positive results on 44-45 of the same 46 by screening tests and all 46 positives by the supplemental test. There were no false positive samples using urine when compared with the serum pairs. The one false negative sample using urine was still nonreactive when the urine volume was increased to 200 microliters using the screening tests. Generally, five times the serum volume was required for the screening tests to be optimal for urine samples. The urine samples were stored under different conditions prior to testing to determine the influence on antibody stability in urine.

Adult↗
PubMed1994

Enhanced chemiluminescence as a means of increasing the sensitivity of western blot assays for HIV antibody.

Chemiluminescence indicator systems offer several advantages for diagnostic assays and have been used successfully to increase the sensitivity of antibody and antigen assays. A technique of enhanced chemiluminescence (ECL) was applied as a replacement for routine chromogenic substrates on HIV-1 Western blots. The results indicated that the enhanced chemiluminescence detection system increased the sensitivity by greater than 10-fold over routine chromogenic indicator systems when testing diluted, reactive sera. When testing 9 seroconversion panels, the use of ECL indicated that early detection of HIV infection was elicited in six panels up to 31 days (average 11.4 days) prior to detection by routine FDA-licensed Western blots, and could be detected in all panels up to 43 days (average 18.8 days) prior to detection by in-house Western blots. In no case was the ECL Western blot system less sensitive than any of the chromogenic Western blots, and in several cases the maximum potential of the ECL system for early detection of antibody could not be determined. The ECL system was capable of detecting antibodies to envelope antigens at a 20-fold increase over chromogenic Western blots. The time of detection of seropositivity by the ECL Western blot was equal to that of most ELISAs in 5 panels and was 31 days earlier than ELISA in one panel. Permanent documentation of Western blot profiles was accomplished using a simple instamatic camera system capable of detecting the chemiluminescence signal, and blots could be re-probed using a second sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Western↗
PubMed1994

Application of a rapid assay for detection of antibodies to human immunodeficiency virus in urine.

The use of rapid, simple tests to detect antibodies to human immunodeficiency virus (HIV) in urine could be valuable for several testing situations, such as in private offices, for epidemiologic surveys, and in developing countries. The authors evaluated the performance of the SUDS HIV type 1 test to detect antibody to HIV-1 peptides in urine. Test performance and applicability of the SUDS test were compared with a routine Food and Drug Administration-licensed enzyme-linked immunosorbent assay (ELISA) and Western blot using 139 serum and urine pairs collected from autopsy cases. Using a modified procedure when testing urine by the SUDS test, results indicated that a total of 15 serum/urine pairs were HIV-1 antibody positive by both the SUDS test and ELISA; all could be confirmed positive by Western blot. One sample produced discrepant results. The SUDS test produced no false-positive results when testing serum or urine, as compared with ELISA, and no false-negative results when compared with the Western blot. For optimal accuracy of detection of antibodies using urine, at least 100 microL of sample was required. By Western blot analysis, antibody profiles in urine were generally weaker than in serum, but confirmation of positivity was not compromised when larger volumes were used. The authors concluded that this rapid HIV-1 test, when used to detect antibodies to HIV-1 in urine, is accurate, easy to perform, and appropriate for use in certain testing situations.

Blotting, Western↗