Search PubMed⌕ Search

Biomedical subjects

P Lepage

Publications and source records attributed to P Lepage.

At least 73 records · Page 4Linked to original sources
PubMed1993

Neurodevelopmental testing of children born to human immunodeficiency virus type 1 seropositive and seronegative mothers: a prospective cohort study in Kigali, Rwanda.

OBJECTIVE: The results of developmental testing of 218 children born to human immunodeficiency virus (HIV)-seropositive mothers and infected or uninfected themselves were compared with those of 218 children born to HIV-seronegative mothers in an ongoing cohort study in Kigali, Rwanda. METHODS: When the children were 6, 12, 18, and 24 months of age, a specific neurodevelopmental examination was performed blindly by study physicians assessing gross motor development, fine motor development, language acquisition, and social contacts. RESULTS: Only one acute severe HIV-related encephalopathy was identified among the 50 infected children. The proportion of abnormal neurologic examinations in HIV-infected children varied from 15% to 40% according to age and was always higher than in HIV-uninfected children born to HIV-seropositive and seronegative mothers (< or = 5% or less of abnormal examinations at each time period). After excluding those children with clinical acquired immunodeficiency syndrome (AIDS) from the analysis, the proportion of abnormal examinations in infected children was 12.5% at 6 months, 16% at 12 months, 20% at 18 months, and 9% at 24 months of age and was still more frequent than in HIV-uninfected children. The developmental delay was principally due to significantly lower gross motor scores. CONCLUSIONS: HIV-1-infected children are more frequently developmentally delayed than uninfected children during the first 2 years of life in this African population. This developmental delay is related to the AIDS stage of pediatric HIV infection.

Child Development↗
PubMed1992

Isolation of the leucine aminopeptidase gene from Aeromonas proteolytica. Evidence for an enzyme precursor.

The leucine aminopeptidase of Aeromonas proteolytica (EC 3.4.11.10) is a monomeric metalloenzyme having the capacity to bind two Zn2+ atoms in the active site. Structural information of this relatively small aminopeptidase that could illuminate the catalytic mechanism of the metal ions is lacking; hence, we have obtained sequences from the purified enzyme, cloned the corresponding gene, and expressed the recombinant protein in Escherichia coli. The deduced primary amino acid sequence of this secreted protease suggests a potential signal peptide at the NH2 terminus. Expression of the recombinant and native proteins in E. coli and in extracts of culture media of A. proteolytica indicates that the aminopeptidase is secreted as an active and thermosensitive 43-kDa protein that is rapidly transformed to thermostable forms of 30 and 32 kDa. Comparison of the deduced amino acid sequence of the A. proteolytica leucine aminopeptidase with other Zn(2+)-binding metalloenzymes failed to show homologies to the consensus binding sequence His-Glu-X-X-His for the metal ion.

Aeromonas↗
PubMed1992

Safety and immunogenicity of high-dose Edmonston-Zagreb measles vaccine in children with HIV-1 infection. A cohort study in Kigali, Rwanda.

OBJECTIVE: To compare the reactogenicity and immunogenicity of high-dose Edmonston-Zagreb (EZ) measles vaccine in children with and without human immunodeficiency virus, type 1 (HIV-1), infection. DESIGN: Prospective cohort study. SETTING: General pediatric clinic and home visits in Kigali, the capital of Rwanda. PARTICIPANTS: Infants born to HIV-1-seropositive and -seronegative mothers were vaccinated with a 10(5.0) 50% tissue culture infective dose of EZ measles vaccine at 6 months of age. Control visits were made 10 and 14 days later to monitor local and general reactions. Measles serum antibodies were measured by an enzyme-linked immunosorbent assay technique at birth and at 6 and 9 months of age. Three groups were compared: infected children (n = 43), uninfected children born to seropositive mothers (n = 135), and uninfected children born to seronegative mothers (n = 194). RESULTS: Three hundred twenty-three children (86.8%) were available for the reactogenicity study. No statistically significant difference between the three groups was found in the occurrence of minor adverse reactions. No severe adverse reaction was observed. One hundred ninety children (51.1%) were available for the immunogenicity study. The percentage of infants negative for measles antibody at 6 months was significantly higher (P = .021) in HIV-infected children (85%) and in uninfected children born to seropositive mothers (90%) than in uninfected children born to seronegative mothers (75%). The overall seroconversion rate at 9 months was 90% (95% confidence interval, 85.7% to 94.3%), without any statistically significant difference between the three groups. CONCLUSION: High-dose EZ vaccine administered at 6 months of age is safe and highly immunogenic in both HIV-infected and uninfected children.

Antibodies, Viral↗
PubMed1992

Biological markers associated with prolonged survival in African children maternally infected by the human immunodeficiency virus type 1.

Sixteen children over the age of 5 years (Group 1) have been identified out of 537 children infected by human immunodeficiency virus and born to HIV-infected mothers, in Kigali, Rwanda. They were followed up for 2 years and compared with 16 younger AIDS patients (Group 2) and with 16 age- and gender-matched HIV-1 seronegative children (Group 3). Fourteen Group 1 subjects had anti-HIV-1 IgM which persisted during the entire study period, in 11 cases directed to HIV-1 envelope proteins. In vitro, immortalization of B lymphocytes by the Epstein-Barr virus confirmed a high production of IgM to envelope proteins. All these patients had anti-p 17 IgG which was not observed in 7 patients from Group 2. All 16 children mounted significant titers of neutralizing antibodies to HTLV-IIIB, and, in 8 patients tested, against two other HIV-1 strains, RII and MN. HIV-1-specific major histocompatibility complex (MHC)-restricted cytotoxic T cells were demonstrated in 3 of 5 of the subgroup who were tested. Prolonged survival over 5 years in children with maternally acquired HIV-1 infection is associated with a high titer of neutralizing antibodies, a persistent production of IGM to HIV-1 envelope proteins and of IgG to p 17.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1992

Mother-to-infant transmission of human immunodeficiency virus by breast milk: presumed innocent or presumed guilty?

This article reviews the virological and epidemiological data available on transmission of the human immunodeficiency virus type 1 (HIV-1) by breast milk. Colostrum and breast milk are considered major modes of transmission for many animal retroviruses as well as human T-cell leukemia virus, mainly as the consequence of ingestion of infected cells. Several cases that strongly suggest transmission of HIV-1 through breast-feeding have now been reported. In addition, recent evidence suggests that postpartum HIV-1 seroconversion of a mother may be associated with a high risk of postnatal transmission to offspring via breast milk. Preventive measures such as pasteurization of breast milk have not been fully examined. While the World Health Organization continues to promote breast-feeding in areas where no safe alternative exists, the Centers for Disease Control recommends that American women who are infected by HIV-1 not practice breast-feeding if a safe alternative is available. Large-scale, carefully controlled, prospective studies of the risk of HIV-1 infection associated with breast-feeding are of the utmost priority. Feasible and ethically acceptable feeding alternatives should be developed for countries where formula feeding has a strong negative effect on child morbidity and mortality.

Animals↗
PubMed1992

Estimating the incubation period of paediatric AIDS in Rwanda.

OBJECTIVE: To estimate the distribution of the incubation period of paediatric AIDS in Rwanda. DESIGN: Data were collected between February 1984 and December 1990 at the Centre Hospitalier de Kigali (CHK), the capital city of Rwanda, Central Africa. PATIENTS: We used a sample of 685 AIDS cases registered consecutively in the Department of Paediatrics of the CHK, in which the proportion of perinatally acquired HIV-1 infection was estimated to be 98.6%. METHODS: We performed both non-parametric and parametric analyses. The methods of estimation were adapted to truncated data, using essentially the same methods as Auger et al. in their analysis of data from the New York City and the New York State AIDS case registries in 1988. RESULTS: We found that a double Weibull model fitted the data very well and that the risk of developing AIDS was high for subjects under 18 months of age, but lower for older subjects. CONCLUSIONS: Our results were qualitatively similar to those of Auger et al.. There were quantitative differences between the two studies, but it was not possible to compare median survival periods. Parameters such as median or mean survival times cannot be validly estimated using only data from registers because these data exclude infected subjects who have not yet developed AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The secondary structure of echistatin from 1H-NMR, circular-dichroism and Raman spectroscopy.

Detailed biophysical studies have been carried out on echistatin, a member of the disintegrin family of small, cysteine-rich, RGD-containing proteins, isolated from the venom of the saw-scaled viper Echis carinatus. Analysis of circular-dichroism spectra indicates that, at 20 degrees C, echistatin contains no alpha-helix but contains mostly beta-turns and beta-sheet. Two isobestic points are observed as the temperature is raised, the conformational changes associated with that observed between 40 degrees C and 72 degrees C being irreversible. Raman spectra also indicate considerable beta-turn and beta-sheet (20%) structure and an absence of alpha-helical structure. Three of the four disulphide bridges are shown to be in an all-gauche conformation, while the fourth adopts a trans-gauche-gauche conformation. The 1H-NMR spectrum of echistatin has been almost fully assigned. A single conformation was observed at 27 degrees C with the four proline residues adopting only the trans conformation. A large number of backbone amide protons were found to exchange slowly, but no segments of the backbone were found to be in either alpha-helical or beta-sheet conformation. A number of turns could be characterised. An irregular beta-hairpin contains the RGD sequence in a mobile loop at its tip. Two of the four disulphide cross-links have been identified from the NMR spectra. The data presented in this paper will serve to define the structure of echistatin more closely in subsequent studies.

Amino Acid Sequence↗
PubMed1991

Purification and biochemical characterization of recombinant alpha 1-antitrypsin variants expressed in Escherichia coli.

Site-directed variants of alpha 1-antitrypsin (alpha 1AT) expressed in a recombinant strain of Escherichia coli have been isolated with an overall process yield of 50% following tangential flow ultrafiltration, anion-exchange, immobilized metal affinity, and hydrophobic interaction chromatography. The primary structure of the purified variants including the integrity of the N- and C-termini has been verified by electrospray mass spectrometry of the intact molecules (44 kDa) for two of the variants (alpha 1AT Leu-358 and alpha 1AT Ala-357, Arg-358). Complementary classical peptide mapping and automated amino acid sequencing have verified 75% of the primary sequence of alpha 1AT Ala-357, Arg-358. Isoelectric focusing in an immobilized pH gradient revealed some microheterogeneity which proved to be reproducible from one purification batch to another. The isolated variants of alpha 1AT did not show any signs of proteolytic degradation during the purification process and proved to be fully active against their target proteases. The described process also allowed the complete removal of endotoxins from the preparations, opening the possibility to evaluate these novel protease inhibitors for their in vivo efficacy in different animal models of human disease.

Amino Acid Sequence↗
PubMed1991

Determination of disulfide bridges in natural and recombinant insect defensin A.

The primary-structure comparison of natural insect defensin A from Phormia terranovae and recombinant insect defensin A from Saccharomyces cerevisiae has been accomplished using a combination of Edman degradation and liquid secondary ion mass spectrometry. The natural and recombinant proteins have the same primary structure with identical disulfide-bond designations (formula; see text) as determined from the peptides obtained after thermolysin digestion. The combined use of Edman degradation and mass spectometry allowed the disulfide-bridge structure to be determined with a total of only 40 micrograms (9.9 nmol) natural peptide. Mass spectrometry provides a rapid means of disulfide-bridge verification, requiring not more than 20 micrograms recombinant insect defensin A, which is compatible with use in batch analysis.

Amino Acid Sequence↗
PubMed1991

Thrombin cleavage analysis of a novel antihaemophilic factor variant, factor VIII delta II.

Factor VIII delta II is a genetically engineered deletion variant of factor VIII expressed by recombinant Chinese hamster ovary cells, in which a major portion of the central (B) domain and a part of the light chain (Pro771-Asp1666) are missing. After immunoaffinity purification, the kinetics of thrombin cleavage of the novel molecule was analysed by SDS/PAGE, Western blotting and N-terminal amino acid sequencing. Thrombin first cleaves factor VIII delta II at Arg740-Ser741 to generate the 90-kDa heavy chain and an 80-kDa fusion polypeptide consisting of the remaining portion of the B domain and the 73-kDa light chain. The 90-kDa fragment is further cleaved, giving rise to 50-kDa and 40-kDa fragments while the 80-kDa fragment generates a 71/73-kDa doublet. The 71/73-kDa doublet, 50-kDa and 40-kDa fragments were further analysed by N-terminal amino acid sequencing and found to correspond to the predicted amino acid sequences. Our study shows that, in spite of the 900 amino acid deletion present in factor VIII delta II, the essential structural elements required for thrombin activation are conserved.

Amino Acid Sequence↗
PubMed1991

Clinical and endocrinologic manifestations in perinatally human immunodeficiency virus type 1--Infected children aged 5 years or older.

Sixteen human immunodeficiency virus type 1 (HIV-1)-seropositive children aged 5 to 12 years (nine girls and seven boys), born to HIV-1-infected mothers, were diagnosed between 1984 and 1987 in Kigali, Rwanda. They were compared with a group of age- and sex-matched HIV-1-seronegative children consecutively selected from the outpatient department. Two subjects were asymptomatic. Chronic cough was the most frequent symptom (seven of 16 patients). The most common signs were short stature (12 of 16 patients), low weight for age (seven of 16 patients), chronic parotitis (eight of 16 patients), persistent generalized lymphadenopathy (seven of 16 patients), and pulmonary tuberculosis (four of 16 patients). Lymphoid interstitial pneumonitis was diagnosed on radiologic grounds in five of 16 patients. Evidence of perivasculitis in the fundus was noted in three of 16 patients. Two children died during the study period (mean duration of follow-up, 40 months; range, 27 to 62 months); none of the other children had life-threatening infection or loss of developmental milestones. Immunologic assessment in the 16 children revealed high levels of IgG, decreased CD4+/CD8+ ratio, and skin test anergy. Endocrinologic investigations revealed normal thyroid function and normal basal human growth hormone levels but low basal insulinlike growth factor I levels (0.21 +/- 0.07 vs 0.44 +/- 0.20 U/mL for controls). In Kigali, perinatally HIV-1-infected children surviving beyond 5 years of age often present with moderate signs and symptoms, principally pulmonary involvement, chronic parotitis, and persistent generalized lymphadenopathy. Short stature is the major clinical manifestation in these patients and may be due, in part, to low growth hormone secretion rather than to malnutrition.

Body Height↗
PubMed1991

Human immunodeficiency virus and malaria in a representative sample of childbearing women in Kigali, Rwanda.

In 1986-1987 a consecutive sample of 3702 women presenting to prenatal and pediatric clinics at the only hospital in Kigali, Rwanda, was screened for human immunodeficiency virus (HIV) and malaria infection. The prevalence of HIV antibodies was 29%, and that of malaria parasites was 9%. HIV antibodies were more prevalent in women from the urban center than in those from the outskirts (31% vs. 20%, P less than .001), and malaria parasites showed the opposite prevalence pattern (8% vs. 15%, P less than .001); after stratifying by location, there was no association between HIV and the presence or degree of malaria parasitemia. HIV prevalence was 45% in women who had received a blood transfusion between 1980-1985 (before screening of donated blood began), and 28% among the great majority (94%) who had never been transfused. HIV prevalence was 44% in single mothers. 34% in women in common law unions, and 20% in those in legal marriages. These high rates of infection in the general population of Kigali highlight the need to develop effective programs for preventing further spread of sexually transmitted HIV.

Adult↗