Publications by authors named "Noel Sam"

Steroid-responsive encephalopathy, also known as Hashimoto's encephalopathy, is an uncommon autoimmune neuroendocrine disorder linked to thyroiditis. It presents a variable range of clinical symptoms, making it challenging to diagnose. SREAT (steroid-responsive encephalopathy associated with autoimmune thyroiditis) is considered a diagnosis of exclusion.

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Methotrexate (MTX) is a commonly used immunosuppressant and chemotherapeutic agent, widely prescribed for autoimmune diseases such as psoriasis, rheumatoid arthritis, and certain malignancies. It functions by inhibiting dihydrofolate reductase, leading to impaired DNA synthesis and cell proliferation. While generally well-tolerated, MTX has a narrow therapeutic index, and its adverse effects can be severe, including hepatotoxicity, pulmonary toxicity, and hematological complications such as pancytopenia.

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The third variable (V3) loop and the CD4 binding site (CD4bs) of the HIV-1 envelope are frequently targeted by neutralizing antibodies (nAbs) in infected individuals. In chronic infection, HIV-1 escape mutants repopulate the plasma, and V3 and CD4bs nAbs emerge that can neutralize heterologous tier 1 easy-to-neutralize but not tier 2 difficult-to-neutralize HIV-1 isolates. However, neutralization sensitivity of autologous plasma viruses to this type of nAb response has not been studied.

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A national ART program was launched in Tanzania in October 2004. Due to the existence of multiple HIV-1 subtypes and recombinant viruses co-circulating in Tanzania, it is important to monitor rates of drug resistance. The present study determined the prevalence of HIV-1 drug resistance mutations among ART-naive female bar and hotel workers, a high-risk population for HIV-1 infection in Moshi, Tanzania.

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The study estimated the prevalence of HIV-1 intra-subtype recombinant variants among female bar and hotel workers in Tanzania. While intra-subtype recombination occurs in HIV-1, it is generally underestimated. HIV-1 env gp120 V1-C5 quasispecies from 45 subjects were generated by single-genome amplification and sequencing (median (IQR) of 38 (28-50) sequences per subject).

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This study analyzed the distribution and prevalence of HIV-1 subtypes, multiplicity of HIV-1 infection, and frequency of inter-subtype recombination among HIV-1-infected female bar and hotel workers in Moshi, Kilimanjaro Region, Tanzania, from 2004 to 2007. The HIV-1 viral sequences spanning the V1-C5 region of HIV-1 env gp120 were analyzed from 50 subjects by single genome amplification and sequencing (SGA/S) technique. A total of 1740 sequences were amplified and sequenced from the HIV-1 proviral DNA template.

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Plasma from a small subset of subjects chronically infected with HIV-1 shows remarkable magnitude and breadth of neutralizing activity. From one of these individuals (CH0219), we isolated two broadly neutralizing antibodies (bnAbs), CH01 and VRC-CH31, from two clonal lineages of memory B cells with distinct specificities (variable loop 1 and 2 [V1V2] conformational specificity and CD4-binding site specificity, respectively) that recapitulate 95% of CH0219 serum neutralization breadth. These data provide proof of concept for an HIV-1 vaccine that aims to elicit bnAbs of multiple specificities.

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Variable regions 1 and 2 (V1/V2) of human immunodeficiency virus-1 (HIV-1) gp120 envelope glycoprotein are critical for viral evasion of antibody neutralization, and are themselves protected by extraordinary sequence diversity and N-linked glycosylation. Human antibodies such as PG9 nonetheless engage V1/V2 and neutralize 80% of HIV-1 isolates. Here we report the structure of V1/V2 in complex with PG9.

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Antibody VRC01 is a human immunoglobulin that neutralizes about 90% of HIV-1 isolates. To understand how such broadly neutralizing antibodies develop, we used x-ray crystallography and 454 pyrosequencing to characterize additional VRC01-like antibodies from HIV-1-infected individuals. Crystal structures revealed a convergent mode of binding for diverse antibodies to the same CD4-binding-site epitope.

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V2/V3 conformational epitope antibodies that broadly neutralize HIV-1 (PG9 and PG16) have been recently described. Since an elicitation of previously known broadly neutralizing antibodies has proven elusive, the induction of antibodies with such specificity is an important goal for HIV-1 vaccine development. A critical question is which immunogens and vaccine formulations might be used to trigger and drive the development of memory B cell precursors with V2/V3 conformational epitope specificity.

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Anaemia during pregnancy is associated with negative maternal and neonatal outcomes. However, there is limited data regarding prevalence and effects of anaemia during pregnancy in northern Tanzania. The objective of this study was to determine the prevalence and possible risk factors for anaemia and its effect on perinatal outcomes among pregnant women attending antenatal care in Moshi Municipality in northern Tanzania.

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There is limited information on alcohol problem drinking, which has been associated with sexually transmitted infections (STIs), including HIV, among female bar/hotel workers in Africa. This paper aimed to identify the individual- and facility-level determinants of alcohol problem drinking in this setting. Problem drinking was defined based on the CAGE alcohol screening scale.

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Background: Substantial heterogeneity in HIV prevalence has been observed within sub-Saharan Africa. It is not clear which factors can explain these differences. Our aim was to identify risk factors that could explain the large differences in HIV-1 prevalence among pregnant women in Harare, Zimbabwe, and Moshi, Tanzania.

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Objectives: To determine the prevalence of sexually transmitted infections (STIs) and other reproductive tract infections (RTIs) among pregnant women in Moshi, Tanzania and to compare the occurrence of STIs/RTIs among human immunodeficiency virus (HIV)-infected and uninfected women.

Methods: Pregnant women in their 3rd trimester (N = 2654) were recruited from two primary health care clinics between June 2002 and March 2004. They were interviewed, examined and genital and blood samples were collected for diagnosis of STIs/RTIs and HIV.

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Background: Factors related to specific sexual encounters can influence condom use during these encounters. These situation-specific factors have not been adequately studied in resource-poor countries where HIV infection has in some areas reached epidemic levels. This study was undertaken to identify situation-specific factors associated with condom use among 465 female bar and hotel workers in Moshi, Tanzania.

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Entamoeba moshkovskii and Entamoeba dispar are microscopically indistinguishable from the pathogenic species Entamoeba histolytica. There are limited data on the prevalence of these commensal infections from Africa. We utilized PCR and antigen detection to evaluate the carriage rate of E.

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Objective: To investigate the magnitude of rural in-migration and the role of in-migrants in the observed increase in HIV-1 prevalence in rural Kilimanjaro, Tanzania.

Methods: A cross-sectional study involving the adult population aged 15-44 years residing in a rural village was conducted from March to May of 2005. Participants were interviewed regarding their risk behaviors and gave blood for HIV-1 and syphilis testing.

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Objectives: To examine the relationship between patterns of alcohol use and HIV infection and to assess the association between problem drinking and the prevalence of risk factors for HIV among a sample of high-risk African women.

Methods: Baseline data were collected between 2002 and 2003 during enrollment of 1050 women in a prospective cohort study designed to assess risk factors for HIV. Information about demographic and employment characteristics, sexual behaviors, and drinking patterns were obtained by interviews.

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Background: Trimethoprim-sulfamethoxazole (SXT) reduces morbidity and mortality among HIV-infected persons in Africa, but its impact on antimicrobial resistance is of concern.

Methods: HIV-uninfected (group A), HIV-infected but not requiring SXT (group B), and HIV-infected and eligible for SXT (group C) adults were recruited into a prospective observational cohort study in Moshi, Tanzania. Stool was examined for Escherichia coli nonsusceptible to SXT at baseline and at weeks 1, 2, 4, and 24.

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Clinical criteria are recommended to select HIV-infected patients for initiation of antiretroviral therapy when CD4 lymphocyte testing is unavailable. We evaluated the performance characteristics of WHO staging criteria, anthropometrics, and simple laboratory measurements for predicting CD4 lymphocyte count (CD4 count) <200 cells/mm(3) among HIV-infected patients in Tanzania. A total of 202 adults, diagnosed with HIV infection through community-based testing, underwent a detailed evaluation including staging history and examination, anthropometry, complete blood count, erythrocyte sedimentation rate (ESR), and CD4 count.

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Background: Tuberculosis (TB) in Africa is increasing because of the human immunodeficiency virus (HIV) epidemic, and in HIV/AIDS patients it presents atypically. Pulmonary tuberculosis (PTB) in Africa is mainly diagnosed clinically, by chest radiograph or by sputum smear for acid fast bacilli (AFB).

Methods: We evaluated in 120 HIV-infected patients with chest infection the diagnostic accuracy of AFB smear of sputum and bronchoalveolar lavage (BAL) fluid, sputum Mycobacterium tuberculosis (MTB) culture, real-time PCR and MycoDot serological test, using MTB culture of BAL fluid as gold standard.

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Background: Monitoring dynamics in HIV-1 infection and risk behaviours is important in evaluating, adjusting and scaling up prevention programmes. The objective of this study was to estimate trends in the prevalence of HIV-1 infection and risk behaviours over 15 years in a rural village population in Kilimanjaro region of Tanzania using repeated population-based cross-sectional surveys.

Methods: Four rounds of HIV-1 sero-epidemiological and behavioural surveys were completed during 1991 to 2005 in the study village.

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Background: Tuberculosis (TB) is a major health problem and HIV is the major cause of the increase in TB. Sub-Saharan Africa is endemic for both TB and HIV infection. Determination of the prevalence of M.

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Background: Variability in stages of the HIV-1 epidemic and hence HIV-1 prevalence exists in different areas in sub-Saharan Africa. The purpose of this study was to investigate the magnitude of HIV-1 infection and identify HIV-1 risk factors that may help to develop preventive strategies in rural Kilimanjaro, Tanzania.

Methods: A cross-sectional study was conducted between March and May of 2005 involving all individuals aged between 15-44 years having an address in Oria Village.

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Background: We examined the role of herpes simplex virus type 2 (HSV-2) and other genital infections on human immunodeficiency virus type 1 (HIV-1) incidence in a cohort study conducted between 2002 and 2005 among female bar/hotel workers in Moshi, Tanzania.

Methods: At baseline and every 3 months thereafter, participants were interviewed, and blood and genital samples were collected. Predictors of HIV-1 incidence were evaluated using a Cox proportional hazards regression model.

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