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Biomedical subjects

P Piot

Publications and source records attributed to P Piot.

At least 55 records · Page 3Linked to original sources
PubMed1995

Risk factors for mother-to-child transmission of human immunodeficiency virus-1 infection.

OBJECTIVE: Our aim was to examine maternal, obstetric, and infant characteristics of mother-to-child transmission of human immunodeficiency virus-1 in Nairobi, Kenya. STUDY DESIGN: Proviral human immunodeficiency virus-1 was detected by polymerase chain reaction in peripheral blood samples taken between 6 weeks and 3 months of age from 107 children born to human immunodeficiency virus-1 seropositive women. The association of maternal, infant, and obstetric variables with human immunodeficiency virus-1 transmission was examined. RESULTS: The mother-to-child transmission rate was 31% (95% confidence interval 21.6 to 40.2) as defined by the presence of proviral human immunodeficiency virus-1 in the infant. Variables associated with transmission in a univariate analysis included placental inflammation (7/12 in the transmitting group as compared with 2/22 in nontransmitters, p = 0.006), low maternal CD4 and high CD8 percentages (21% and 52%, respectively, in transmitting mothers and 32% and 40% in nontransmitting mothers; p = 0.001), and the gender of the neonate (20/29 infected neonates were female as compared with 26/65 noninfected children, p = 0.02). Sexually transmitted diseases were found more often in transmitting mothers but the differences were not significant. Birth weight and gestational age were not related to vertical transmission of human immunodeficiency virus-1. CONCLUSION: Risk factors for mother-to-child transmission of human immunodeficiency virus-1 included chorioamnionitis, an impaired maternal immune status, and female gender.

Adult↗
PubMed1995

Evaluation and comparison of the Amplicor HIV-1 PCR kit with an 'in-house' nested PCR.

BACKGROUND: The polymerase chain reaction (PCR), a powerful gene amplification technique, is moving rapidly from the research laboratory into routine clinical use. OBJECTIVES: To evaluate the specificity and sensitivity of a commercially available PCR kit, the Amplicor HIV-1 PCR kit (AMP) and to compare it with an in-house nested PCR, which amplified part of the POL gene (POL(n)). STUDY DESIGN: A total of 517 samples were tested by AMP, including 159 fresh whole blood specimens from HIV-1 antibody positive Europeans and 358 archival samples (338 seropositive and 20 seronegative individuals) originating from 35 different countries in Africa and Europe. We compared the performance of AMP on the archival samples with POL(n). RESULTS: The overall sensitivity and specificity as compared to HIV-1 serology were 93% and 100%, and 96% and 100%, for AMP and the in-house PCR, respectively. Repeat testing on co-cultured lymphocytes increased the sensitivity of AMP to 95%. CONCLUSIONS: AMP is a rapid, and easy to use commercially available PCR kit, since only one amplification of the test sample is required. Moreover, the use of radioactivity is omitted, and reading of the test can be done with a spectrophotometer. The use of at least one additional primer pair may increase confidence in distinguishing a positive and negative sample by both PCR techniques.

Journal Article↗
PubMed1995

Correlation between genetic and biological properties of biologically cloned HIV type 1 viruses representing subtypes A, B, and D.

The relationship between the genetic variability in the V3 loop and the biological characteristics of 38 biological clones from 5 European and 7 African HIV-1 isolates belonging to 3 different subtypes (subtype A, B, and D) was investigated. Seventeen of 19 clones displaying a syncytium-inducing (SI) capacity had a positively charged amino acid located at position 11 and/or 25 in the V3 loop sequence. All 19 non-syncytium-inducing (NSI) virus clones lacked such a positive charge at the same positions (p < 0.001). The mean of net charge in the overall V3 loop sequences of the SI clones was higher than that of the NSI clones (p < 0.001). Within the same strains, the SI clones replicated faster/higher than the NSI clones in peripheral blood mononuclear cells (p < 0.01), but not in CD4+ T cell cultures (p > 0.1). All SI clones but only 5 of 19 NSI clones could replicate in human continuous T cell and monocytic cell lines (p < 0.001). A higher number of positively charged amino acid substitutions was found among the subtype D SI clones. Only one of eight autologous sera tested had the ability to neutralize the contemporaneously isolated NSI clones, but not the SI clones. This study indicates that the V3 loop amino acid sequences of HIV-1 biological clones from different origins belonging to different genetic subtypes are clearly correlated with viral syncytium-inducing capacity, cell tropism, and replication rate.

Amino Acid Sequence↗
PubMed1995

Failure of treatment for chancroid in Rwanda is not related to human immunodeficiency virus infection: in vitro resistance of Haemophilus ducreyi to trimethoprim-sulfamethoxazole.

A comparative open study was performed to evaluate the efficacy of single doses of ciprofloxacin (500 mg) and trimethoprim-sulfamethoxazole (TMP-SMZ; 640 mg/3,200 mg) for the treatment of culture-proven chancroid. Clinical cure or improvement was observed 7 days after treatment in 32 (76.2%) of the 42 patients who received ciprofloxacin and 21 (52.5%) of the 40 patients who received TMP-SMZ (P = .04). Cultures for one (4.5%) of 22 patients not cured with ciprofloxacin and 16 (59.3%) of 27 patients not cured with TMP-SMZ were still positive for Haemophilus ducreyi 7 days after treatment (P < .001). Although 77 (71.3%) of the 108 patients tested were seropositive for HIV-1 antibody, HIV infection and the degree of CD4+ lymphocyte depletion had no effect on clinical and bacteriologic outcome. All isolates of H. ducreyi were highly susceptible to ciprofloxacin (MIC, 0.004-0.06 mg/L). In contrast, resistance to TMP-SMZ (MIC, > or = 4/76 micrograms/mL) was observed in 48.9% of isolates (22 of 45) and was significantly associated with treatment failure. Therefore, the administration of TMP-SMZ, in single or multiple doses, is no longer indicated for the treatment of chancroid in Rwanda.

Adult↗
PubMed1995

Frequent use of menfegol spermicidal vaginal foaming tablets associated with a high incidence of genital lesions.

Menfegol is a spermicide with in vitro activity against human immunodeficiency virus (HIV). A randomized placebo-controlled safety study covered the use of menfegol foaming tablets for 14 days at increasing frequencies of insertion by 125 prostitutes in Dakar, Senegal. The frequencies of colposcopically diagnosed genital lesions were 5.0%, 11.8%, 27.8%, 49.7%, and 29.4% among menfegol recipients when tablets were used once every other day or 1, 2, 4, or 8 times a day, respectively (P < .05). Among placebo recipients, frequencies were 11.1% and 23.5% when tablets were used < 8 times daily and 8 times daily, respectively. There was no association between subjective genital symptoms and the incidence of colposcopically detected lesions. The high incidence of genital lesions when menfegol foaming tablets were used more than once daily suggests that their frequent use should not be recommended to prevent HIV transmission. In use at low frequency, the tablets' toxicity might be balanced by anti-HIV properties. Safety studies on vaginal microbicides should use objective methods, such as colposcopy, to assess the incidence of lesions.

Adult↗
PubMed1995

In vitro stimulation of peripheral blood mononuclear cells (PBMC) from HIV- and HIV+ chancroid patients by Haemophilus ducreyi antigens.

The cellular immune responses to fractionated Haemophilus ducreyi antigens, coated on latex beads, were assessed in patients with chancroid and in controls, using an in vitro lymphocyte proliferation assay. Several fractions of H. ducreyi antigen revealed stimulating activity. However, only the molecular size ranges 91-78 kD, 59-29 kD, and 25-21 kD induced proliferation that may be specifically related to H. ducreyi infection. Lymphocytes from four HIV- patients, successfully treated for chancroid, were not stimulated by H. ducreyi antigen. In general, lymphocytes from HIV+ chancroid patients were less responsive to H. ducreyi antigen compared with those from HIV- chancroid patients. However, two HIV-infected patients showed exceptionally strong responses to high molecular weight fractions. To our knowledge this is the first report demonstrating that H. ducreyi contains specific T cell-stimulating antigens. Based on this work, further identification and purification of the T cell antigens is feasible.

Antigens, Bacterial↗
PubMed1995

Monoclonal antibodies against Haemophilus lipopolysaccharides: clone DP8 specific for Haemophilus ducreyi and clone DH24 binding to lacto-N-neotetraose.

Mouse monoclonal antibodies (MAbs) DP8 [immunoglobulin G1(kappa)] and DH24 [immunoglobulin M(kappa)], which are specific for Haemophilus ducreyi lipopolysaccharide (LPS), were generated by fusing mouse myeloma NS0 cells with spleen cells of BALB/c mice immunized with a total membrane preparation of H. ducreyi. MAb DP8 reacted in whole-cell enzyme immunoassay (EIA) and colony dot immunoblotting with all 50 strains of H. ducreyi but not with any other bacteria tested, which suggests an exposed and species-specific epitope on the H. ducreyi cell surface. This conclusion was supported by the finding that DP8 bound to all six H. ducreyi LPSs tested but not to any of the Haemophilus influenzae or enterobacterial LPSs or synthetic glycoconjugates. The MAb DH24 bound to 43 of 50 strains of H. ducreyi and to few strains of H. influenzae, Neisseria gonorrhoeae, and Neisseria meningitidis, as evaluated by whole-cell EIA and colony dot immunoblotting. The MAb DH24 reacted with five of the six H. ducreyi LPSs tested and with the lacto-N-neotetraose (Gal beta 1-->4GlcNAc beta 1-->3Gal beta 1-->4Glc) series of synthetic glycoconjugates, as determined by EIA. By using polysaccharides obtained after both mild acidic hydrolysis and strong alkali treatment and dephosphorylated samples as inhibitors of the MAbs binding to H. ducreyi LPS antigens, it could be shown that phosphate groups were essential for the binding of DP8 to LPS but that they did not affect antigenic recognition by DH24. None of the MAbs bound to isolated lipid A, but aggregation caused by the fatty acids of lipid A was essential for epitope recognition.

Animals↗
PubMed1995

Similar serological response to conventional therapy for syphilis among HIV-positive and HIV-negative women.

OBJECTIVES: To compare characteristics of syphilis serological reactivity in HIV positive (+) and HIV negative (-) female sex workers, as well as the serological response to therapy after treatment with intramuscular benzathine penicillin, 2.4 million U weekly, for three consecutive weeks. METHODS: Rapid plasma reagin (RPR) and Treponema pallidum haemagglutination assay (TPHA) results of 72 HIV-positive and 121 HIV-negative women reactive in both tests were assessed. The response to therapy was prospectively monitored with quantitative RPR serology in 47 HIV-positive and 73 HIV-negative patients. Cumulative probabilities of becoming nonreactive by RPR were compared at six months, one and two years after therapy. RESULTS: At enrolment, the geometric mean titres of RPR and TPHA were lower in HIV-positive patients (RPR, 1:2.6) than in HIV-negative patients (RPR, 1:3.8; p < 0.01). The evolution over time of RPR titres was similar among HIV-positive patients as compared to HIV-negative patients. Among patients with an initial RPR titre of < 1:8, 53% of HIV-positive and 44% of HIV-negative patients became RPR negative two years after therapy. Among patients with an RPR titre of 1:8 or greater at enrolment, 83% of HIV-positive and 90% of HIV-negative patients had reached at least a fourfold decline of RPR titres two years after therapy. CONCLUSIONS: Syphilis serology findings (both RPR and TPHA) may be altered in the presence of HIV infection, but the serological response to therapy was similar in HIV-positive and HIV-negative patients.

Adult↗
PubMed1995

Community survey of diarrhoea in children under 5 years in Kinshasa, Zaire.

This community based survey was undertaken to assess the prevalence, characteristics and risk factors of diarrhoea in children < 5 years of age in an urban zone, at Kinshasa, Zaire. 155 community cases selected by cluster sampling, 155 age-matched controls, and 18 children with diarrhoea seen at a health centre (HC) were examined. The diarrhoea prevalence rate was 6.5%. The highest risk of persistent diarrhoea was in children of 2 to 3 years, non breast-fed, with more than one enteric agent in their stools and living in households without electricity. The rates of detection of Strongyloides stercoralis, Entamoeba histolytica and Salmonella, and heavy infections of Trichuris trichiura and Trichomonas hominis were significantly higher in cases (p < 0.05). The rate of detection of Cryptosporidium was rather high, specially in HC cases (22.2%). It was also found in both diarrhoeal (14.8%) and non-diarrhoeal specimens (12.9%). There was a lack of association between the presence of faecal white blood cells and enteric bacteria, and also between the presence of faecal red blood cells and E. histolytica, which might be due to the frequent practice of rectal injections and suppositories. A mother's perception of fever and stool aspect was fairly in agreement (respectively 70% and 53%) with that of the investigators. The high rate of dehydrated children (50.9%) may be due to the dehydration definition applied at the HC. The survey's results were used to improve the local case management flow chart and to adjust educational activities directed at mothers.

Animals↗
PubMed1995

Non-response to a recombinant pre-S2-containing hepatitis B vaccine: association with the HLA-system.

In this study, the immunogenicity of a recombinant pre-S2 containing hepatitis B vaccine was determined in a cohort of 147 homosexual men. Both seroconversion rate and geometric mean titers indicated that pre-S2 was less immunogenic than HBsAg. Forty-eight subjects, including nine non-responders and seven high-responders to HBsAg, were tested for HLA Class I and II antigens to study a possible association between HLA-type and non-response. Both HLA-B8 and HLA-DR3 were clearly overrepresented in non-responders to HBsAg. Non-response to pre-S2, observed in 7/9 non responders and 6/39 responders to HBsAg, was not associated with any of the tested HLA markers.

Adult↗
PubMed1995

HIV-1 and immunological changes during pregnancy: a comparison between HIV-1-seropositive and HIV-1-seronegative women in Nairobi, Kenya.

OBJECTIVE: To assess changes in the proportion of CD4 and CD8 T-lymphocyte profiles during pregnancy, at delivery and postpartum, and to determine whether HIV-1 infection affects the normal profile. DESIGN AND METHODS: A total of 416 pregnant HIV-1-infected women and an age and parity-matched HIV-seronegative group of 407 pregnant women were enrolled into a prospective study on the impact of HIV-1 infection on pregnancy. Maternal blood was obtained for lymphocyte subset determination at enrollment, delivery and 6 weeks postpartum. Whole blood sample drawn in EDTA-containing tubes were used to determine T-helper/inducer (CD4) and T-suppressor/cytotoxic (CD8) cells by direct immunofluorescence using monoclonal antibodies. RESULTS: No relationship was found between gestational age and any immunological variable. The CD4 percentage was lower postpartum than antenatally, in both HIV-1-seropositive and seronegative women, but this was not true for absolute CD4 counts. CD8 absolute counts and percentages were significantly higher postpartum than antenatally. The differences between HIV-1-seropositive and seronegative women in changes over pregnancy in CD4 and CD8 cells and their ratio, were not statistically significant. CONCLUSION: Our findings do not support a short-term synergistic effect of HIV-1 and pregnancy on the immune function as determined by T-lymphocyte subsets.

Adult↗
PubMed1995

Simple algorithms for the management of genital ulcers: evaluation in a primary health care centre in Kigali, Rwanda.

A cross-sectional study was conducted among 395 patients presenting with genital ulcers at a primary health care centre in Kigali, Rwanda. Using clinical data and the results of a rapid plasma reagin (RPR) test, we simulated the diagnostic outcome of two simple WHO flowcharts for the management of genital ulcers. These outcomes and a clinical diagnosis were then compared with the laboratory diagnosis based on culture for genital herpes and Haemophilus ducreyi and serology for syphilis. The prevalence of HIV infection was high (73%) but there was no difference between HIV-positive and HIV-negative patients in the clinical presentation and etiology of genital ulcer disease. The proportion of correctly managed chancroid and/or syphilis cases was 99% using a syndromic approach, 82.1% using a hierarchical algorithm including an RPR test, and 38.3% with a clinical diagnosis. In situations where no laboratory support is available, a simple syndromic approach is preferable to the clinical approach for the management of genital ulcer. If an RPR test can be included in the diagnostic strategy, patients with a reactive RPR test should be treated for both syphilis and chancroid infection.

Algorithms↗
PubMed1994

Condom promotion, sexually transmitted diseases treatment, and declining incidence of HIV-1 infection in female Zairian sex workers.

The control of sexually transmitted diseases, including HIV-1, among sex workers and their clients in urban areas in developing countries, is considered a valuable and cost-effective intervention to contain the spread of HIV-1. The effect of a programme of STD treatment combined with condom promotion on HIV-1 incidence has so far not been measured. During an intervention including condom promotion, as well as monthly sexually transmitted disease screening and treatment among 531 initially HIV-1 negative female sex workers in Kinshasa, Zaire, 70 became infected with HIV-1 (incidence of 8.0 per 100 women-years [wy]). A decline of HIV-1 incidence was observed over time, from 11.7/100 wy during the first 6 months, to 4.4/100 wy over the last 6 months, 3 years later (p = 0.003). Simultaneously, regular use of condoms with clients went up from 11% to 52% and 68%, after 6 and 36 months of intervention, respectively. Risk factors for HIV-1 seroconversion after multivariate analysis included irregular condom use (RR 1.6 [95% Cl 1.1-2.8]), gonorrhoea (RR 2.5 [1.1-6.4]), trichomoniasis (RR 1.7 [1.1-2.8]), and genital ulcer disease (RR 2.5 [1.1-6.4]), during the probable period of acquisition of HIV-1. In women who attended more than 90% of their clinic appointments, the HIV-1 incidence was 2.7/100 wy compared to 7.1, 20.3, and 44.1 per 100 wy among women who attended 76-90%, 50-75%, and less than 50% of the monthly appointments, respectively (p < 0.0001). These trends remained after controlling for reported condom use and number of clients. This study confirms earlier findings that STDs facilitate transmission of HIV-1 and shows that a clinic-based intervention consisting of STD care and condom promotion can result in a major decline of HIV-1 incidence among female sex workers.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Design and evaluation of new, highly sensitive and specific primers for polymerase chain reaction detection of HIV-1 infected primary lymphocytes.

Primer pairs in the HIV-1 POL and ENV genes were evaluated by performing a PCR on lysed peripheral blood mononuclear cells (PBMCs) from 96 HIV-1 seropositive and 40 seronegative individuals originating from 16 different geographical localities in Africa, Europe and Haiti. A single PCR using primer pairs to the LTR, GAG and ENV regions and detection by radioactively labelled oligonucleotide probes was compared to a nested PCR scheme using newly designed POL and ENV primers which used ethidium-bromide staining of the amplified product on agarose gel. The newly designed POL nested primer pair was shown to be highly sensitive (93%) and specific (100%) for the detection of HIV-1 proviral DNA of very diverse geographical and genetic origin, including highly aberrant HIV-1 isolates. The sensitivity of the newly designed ENV primers was 68.7%, which does not differ significantly from the sensitivity of the classical primers, SK 68/69. Both ENV primers were unable to amplify two SIVcpz isolates from naturally infected chimpanzees.

Africa↗
PubMed1994

Effect of methodology on detection of HIV-1/HIV-2 dual infections in Côte d'Ivoire.

Dual seroreactivity to the human immunodeficiency virus (HIV) types 1 and 2 is common in Côte d'Ivoire. To assess whether dual infection is the reason for dual seroreactivity, different methods for detection of HIV-1 and HIV-2 viruses were compared. PCR on primary uncultured lymphocytes of 56 dually seropositive samples revealed the presence of both HIV-1 and HIV-2 proviral DNA in 23 (41%) cases. In 7 other dual seropositive persons, PCR was carried out on the primary lymphocytes as well as on lymphocytes after 3 and 6 weeks of cocultivation. More cultures, 5/7 (71%), were positive for both viruses at 3 weeks compared to 0/7 at 6 weeks post cultivation. Moreover, 2 out of 3 samples, where only HIV-1 was detected in uncultured cells, were positive for both viruses after 3 weeks of cultivation. These data indicate that the sensitivity of HIV-2 detection can be increased by stimulation of patients' lymphocytes. A higher number of dual seropositive individuals (10/23 (48%)) had antibodies able to neutralize simultaneously both HIV-1 and HIV-2 prototype viruses than did HIV-1 antibody-positive sera (5/21 (24%)) or HIV-2 antibody positive sera (3/18 (17%)). The prevalence of dual seropositives being infected with both viruses is highly dependent on the method used to detect infection. There is a need to standardize virological markers in order to gain a better insight into the relative proportions of HIV-1, HIV-2 and HIV-1/HIV-2 dually infected persons.

Antibody Specificity↗