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Biomedical subjects

N T Constantine

Publications and source records attributed to N T Constantine.

72 records · Page 4Linked to original sources
PubMed1989

Observations on sexually transmitted diseases in promiscuous males in Djibouti.

Observations are reported on 7 sexually transmitted diseases in a heterosexual population of 105 promiscuous males in Djibouti, East Africa. Neisseria gonorrhoeae was cultured from urethral swabs from 34 subjects. Six isolates were beta lactamase positive (18%). High levels of resistance to antimicrobials were noted with penicillin, spectinomycin and cotrimoxazole, while tetracyclines and erythromycin were unvariably effective. Six patients had Chlamydia urethritis, one of whom had concomitant gonococcal urethritis. Half of the sera reacted positive for antibodies to Chlamydia. A total of 31 subjects had a positive treponemal FTA-Abs test; of these, only 14 had a reactive RPR test. Nineteen individuals were positive for HBsAg. One subject had a western blot confirmed HIV-1 infection, while none had antibodies to HIV-2 or HTLV-I.

AIDS Serodiagnosis↗
PubMed1988

Viral hepatitis markers in Djibouti: an epidemiological survey.

A serosurvey involving 656 individuals revealed that hepatitis A infection was virtually universal in Djibouti in 1987, and more than half of the people investigated had serum markers of hepatitis B infection. The rate of chronic HBsAg carriers was 7.3% and was higher for males than for females. Both HBsAg and anti-HBs positivity rates were directly related to increasing age. No uniform mechanism could be found to account for transmission of the hepatitis B virus, and no correlation was noted between HBV-marker status and sexual promiscuity or the classic blood exposure risks. However, a significant association existed between the abuse of khat and the chronic HBsAg carrier state.

Adult↗
PubMed1983

Antigenic differentiation of the kinetoplastids Leishmania braziliensis and Trypanosoma cruzi by means of monoclonal antibodies.

BALB/c mice were hyperimmunized with non-infectious extracts of either Leishmania braziliensis promastigotes or Trypanosoma cruzi epimastigotes. When spleen cells from these mice were fused with P3X63Ag8 plasmacytoma cells, the resultant hybridomas synthesized monoclonal antibodies which displayed specific reactivity by indirect immunofluorescence with distinct subcellular components of the parasites. These studies revealed that antigens associated with the flagellum and with a nongranular component of the cytoplasm would account for much of the serologic cross-reactivity observed between the two species. Conversely, antigens associated with surface and/or cytoplasmic granules and with an intracellular organelle believed to be the kinetoplast appeared to be species-specific.

Animals↗
PubMed1981

Antigenic differentiation of Trypanosoma cruzi and Trypanosoma rangeli by means of monoclonal-hybridoma antibodies.

Sera from Balb/c mice, hyperimmunized with ruptured epimastigotes of either Trypanosoma cruzi or Trypanosoma rangeli, lacked species-specificity when assayed for antibodies by indirect immunofluorescent microscopy and by the enzyme-linked immunosorbent assay. However, when plasma cells from those mice were fused with syngeneic mouse plasmacytoma cells, many of the resultant hybridomas synthesized antibodies which were species-specific. Four clones are synthesizing antibodies specific for antigens of T. rangeli. These antigens are associated with the cytoplasm, plasma membrane and flagellum. One clone is synthesizing a specific anti-T. rangeli antibody which appears to be reactive with the entire surface of the epimastigote. Another clone is reactive with a subpopulation of epimastigotes, thus suggesting some antigenic variability among cultured forms. Two clones are synthesizing antibody specific for antigens of T. cruzi, one of which is confined to the cytoplasm.

Animals↗
PubMedDate not supplied

Low prevalence of HIV infection in Djibouti--has the AIDS epidemic come to a stop at the Horn of Africa?

To determine if the HIV-epidemic had reached Djibouti by autumn 1987, we investigated 645 subjects belonging to various risk groups; 150 were patients with a disease compatible with acquired immune deficiency or with a mycobacterial infection, 115 were young males having a sexually transmitted disease, 295 were female prostitutes, and 69 were villagers from a rural area; the remaining 16 belonged to other groups. All subjects answered an epidemiological questionnaire and had their serum tested for evidence of HIV antibodies. Eight sera were HIV-antibody positive by both ELISA and Western blot. Of these, 2 were from young men while 6 were from young women who admitted to prostitution. This accounts for an HIV seropositivity rate of 2.0% +/- 1.6% in the prostitute population. Also, one antibody-positive subject was positive for circulating HIV antigen. Seven of the seropositive individuals had no general complaints or abnormal clinical signs. The eighth subject was a 28 year old man in hospital for pneumonia. We conclude that in Djibouti, in late 1987, the prevalence of both AIDS and HIV infection in high risk individuals was much lower than that reported from other East African countries.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

HHV-6 in Djibouti--an epidemiological survey in young adults.

Human herpesvirus type six (HHV-6), previously called human B-cell lymphotropic virus (HBLV), was first isolated in 1986 from patients with various lymphoproliferative disorders, some related to the acquired immunodeficiency syndrome. In order to investigate the epidemiology of HHV-6 in the Horn of Africa, we studied 281 young adults living in the city of Djibouti during June 1988. Of these, 181 belonged to various groups at risk for human immunodeficiency virus (HIV), while 100 represented the normal young adult population. Sera were screened and titrated for antibodies against HHV-6 by an indirect fluorescent antibody assay. The percentage seropositivity for HHV-6 was 71 in the normal population, 75 in the population at risk for HIV, and 93 in the population of subjects with a confirmed positive HIV Western blot. Mean titres of positive sera were similar in all population groups. No correlation existed between HHV-6 seropositivity and age, sex, tribe, habitat, and risk factors for HIV. A positive correlation was noted between HHV-6 and patients complaining of fatigue.

Antibodies, Viral↗
PubMedDate not supplied

Low prevalence of infection by HTLV-I in populations at risk for HIV in Djibouti.

In order to determine whether HTLV-I (a recently discovered retrovirus causing T-cell leukaemias and lymphomas, as well as tropical spastic paraparesis) was present in Djibouti in 1988, we investigated 576 subjects belonging to various groups at risk of acquiring HIV, a related retrovirus transmitted analogously to HTLV-I. Sera were screened by a commercial agglutination assay and confirmation of repeatedly reactive sera was performed by specific Western blot analysis. Four sera were strongly positive for HTLV-I by Western blotting, while one serum displayed equivocal reactivity. All positive sera came from young women who engaged in prostitution. This accounted for an HTLV-I seropositivity rate of 0.7% (95% CI, 0.03-1.4%) in the total study population and 1.2% (95% CI, 0.02-2.4%) in the population engaged in prostitution. We concluded that in Djibouti in June 1988, HTLV-I was present but that the prevalence of infection in high risk individuals was very low.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Multiple blood-borne and sexually transmitted infections in sexually transmitted disease clinic and hospital emergency room patient populations.

The degree of coinfections with blood-borne or sexually transmitted pathogens (HIV-1, HTLV-I/II, HBV, HCV, HDV, and Treponema pallidum) were assessed in individuals attending sexually transmitted diseases (STD) clinic and patients admitted to a hospital through the emergency room in Baltimore. Enzyme-linked immunosorbent assays (ELISA), immunoblots, and card tests were used to screen the sera. Nearly one third of the individuals in both populations were infected with one or more pathogens. With some minor exceptions, all individuals with dual or multiple infections had antibodies reactive with the HBV core antigen. There was a strong overall association between the presence of antibodies to HIV-1 and the presence of antibodies to HBV core and HCV in both populations. Additionally, the presence of HIV-1 antibodies was significantly associated with the presence of HTLV-I/II antibodies and HBV surface antigen in the STD population and with a positive RPR test result in the H/ER population. We suggest that HIV-1 and/or HTLV-I/II infected individuals in STD clinic and emergency rooms are highly likely to have had past infections with HBV or HCV.

Adolescent↗
PubMedDate not supplied

Diagnostic challenges for rapid human immunodeficiency virus assays. Performance using HIV-1 group O, HIV-1 group M, and HIV-2 samples.

OBJECTIVE: We sought to determine the ability of seven rapid assays for human immunodeficiency virus (HIV) to detect antibodies in a panel of sera from individuals infected with different types and groups of HIV. STUDY DESIGN/METHODS: Sixty-eight well-characterized samples, including HIV-1 group O (24), several HIV-1 group M clades (21), HIV-1/2 (10), HIV-2 (10), and samples with indeterminate results (3), were tested by the following rapid HIV assays: HIV-Spot, HIVCHEK System 3, A/Q Rapid HIV, Genie II HIV-1/HIV-2, Quix HIV-1-2-O, ImmunoComb II HIV-1+2 BiSpot, and the Serodia HIV-1+2. RESULTS: All tests successfully detected the HIV-1 group M clades and the HIV-1/2-positive samples. Of the HIV-2 stand-alone samples, four tests missed the same sample, and three tests missed another sample. Of the HIV-1 group O samples, four samples were missed by at least one test, and another sample was missed by three tests. The sensitivity of the seven rapid assays in detecting each group of sera was between 83% and 100%, with only one test having a sensitivity of 100% for all groups of sera. Three samples proved to be problematic because they were misclassified by more than one assay. CONCLUSIONS: The performance of rapid HIV assays is variable when testing sera from individuals infected with HIV-1 group O and HIV-2.

Evaluation Studies as Topic↗
PubMedDate not supplied

Optimization, assessment, and proposed use of a direct nested reverse transcription-polymerase chain reaction protocol for the detection of hepatitis C virus.

OBJECTIVES: To compare the performance of reverse transcription followed by the polymerase chain reaction (RT-PCR), without RNA purification, with the performance of classic protocols. STUDY DESIGN/METHODS: Direct and classic techniques were used to test three groups of samples: six hepatitis C virus (HCV) seroconversion panels (n = 90), a HCV RNA reference panel (n = 26), and serial dilutions of four HCV-positive sera (n = 24). These methods were then applied sequentially through a clinical diagnostic algorithm to test 268 samples from high-risk patients. RESULTS: For the three groups of samples, we found a 94% concordance between direct and purified RT-PCR methods. For the detection of HCV RNA in clinical samples, sensitivity was maximized and cost minimized using both protocols according to the proposed algorithm. CONCLUSIONS: The direct PCR method is reliable, sensitive, and can result in time and cost savings. The suggested testing algorithm can enhance sensitivity and time savings for populations with a high prevalence of infection.

Algorithms↗
PubMedDate not supplied

Hepatitis C in Peru: risk factors for infection, potential iatrogenic transmission, and genotype distribution.

A large seroepidemiologic and genotyping study of hepatitis C virus (HCV) was conducted in Lima, Peru, during the periods of 1986 to 1993 (cohort A) and 1994 (cohort B). Anti-HCV seroprevalence rates were 15.6% (216 of 1,389) and 11.7% (168 of 1,438), respectively. Low rates were seen among volunteer blood donors (1.1% and 0.8%). Anti-HCV rates were much higher among patients undergoing hemodialysis (43.7% and 59.3%), hemophiliacs (60.0% and 83.3%), in those more than 39 years old (18.2% and 26.0%), in females (25.0% and 27.4%), and in less-educated persons (16.9%). Age- and gender-adjusted risk factors in cohort B included blood transfusion history (adjusted odds ratio [AOR] = 29.8), prior organ transplantation (AOR = 9.1) or a history of hepatitis (AOR = 4.9), previous hospitalization (AOR = 3.7), a history of intravenous drug use (AOR = 3.5), prior major surgery (AOR = 2.6), a history of acupuncture (AOR = 2.1), previous dental procedures (AOR = 1.2), and prior medical injections (AOR = 1.04). The most prevalent HCV genotype was type 1 (86%), followed by type 3 (10%) and type 2 (2%). Transmission through unsafe injection-related and medical/dental procedures appears to play an important role in HCV infection among Peruvians.

Adolescent↗
PubMedDate not supplied

Assessment of a rapid HIV test strategy during labor: a pilot study from Rio de Janeiro, Brazil.

OBJECTIVES: To use two rapid human immunodeficiency virus (HIV) tests at labor, measure test acceptance and performance, and measure HIV prevalence in these women. METHODS: Between February and October 2000, two rapid tests (Determine; Abbott, Chicago, IL, U.S.A. and Double Check; Orgenics, Yavne, Israel) were used in three public maternities in Rio de Janeiro, Brazil. Enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) analysis confirmed positive and discordant results. RESULTS: Of the 858 patients who were enrolled, the mean gestational age was 36 weeks (median = 39, mode = 40) and 17 (2%) refused testing. Of the 841 patients tested, 13 were positive by both tests, which represents a 1.5% prevalence (95% confidence interval: 0.7%-2.3%); all were confirmed by ELISA and WB analysis. Seven samples gave discordant results by the rapid tests; of these, six were ELISA-negative/WB-negative and one was ELISA-negative/WB-indeterminate. The positive predictive value for samples that were positive by both rapid tests simultaneously was 100%. CONCLUSIONS: Two rapid HIV tests used at labor were well accepted (98%). When the combined results of the two rapid tests (but not a single rapid test) were analyzed, this strategy was as efficient as the standard ELISA and WB HIV strategy for correctly classifying individuals.

Blotting, Western↗