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Biomedical subjects

C A Hart

Publications and source records attributed to C A Hart.

At least 145 records · Page 8Linked to original sources
PubMed1999

Increased prevalence of malaria in HIV-infected pregnant women and its implications for malaria control.

OBJECTIVES: To examine in pregnant women the relationship between HIV infection and malaria prevalence and to determine, in relation to HIV infection, the effectiveness of sulphadoxine-pyrimethamine in clearing P. falciparum infection. METHOD: Descriptive cross-sectional analysis of P. falciparum prevalence in pregnant women at first antenatal visit and of women at delivery who had received two sulphadoxine-pyrimethamine treatments for malaria. HIV status was assessed in 621 women who attended for antenatal care and for delivery at two rural hospitals in southern Malawi in 1993-94. Information was collected on maternal age, parity and gestational age. Prevalence of P. falciparum was measured at first antenatal visit and delivery. Women were given two routine treatment doses of sulphadoxine-pyrimethamine (SP), at first antenatal visit and between 28 and 34 weeks gestation, conforming to Malawi government policy on antimalarial control during pregnancy. RESULTS: Prevalence of HIV infection was 25.6% and all infections were HIV type-1. In primigravidae malaria prevalence at recruitment was 56.3% in HIV-infected and 36.5% in HIV-uninfected women (P=0.04). The corresponding figures for multigravidae were 23.8% and 11.0%, respectively (P<0.01). HIV-infected primigravidae had increased malaria prevalence at all gestational ages. Peak parasite prevalence occurred earlier in gestation in HIV-infected primigravidae (16-19 weeks if HIV-infected; 20-23 weeks if HIV-uninfected). The relative risk for parasitaemia in HIV-infected compared to HIV-uninfected women was significantly increased in three of five parity groups, including the two highest ones (parity>3), indicating parity-specific immunity to malaria was impaired. Malaria prevalence at delivery remained high in HIV-infected women despite prior routine treatment with sulphadoxine-pyrimethamine in pregnancy There was no significant difference in parasite prevalence at delivery between women who did or did not use sulphadoxine-pyrimethamine. CONCLUSIONS: HIV infection is associated with a significant increase in malaria prevalence in pregnant women of all parities with the effect apparent from early in gestation. Two treatment doses of sulphadoxine-pyrimethamine were inadequate to clear parasitaemia in many women by the time of delivery and this occurred independently of HIV status and despite high sensitivity to SP in this area. There is a need to undertake longitudinal studies to determine the incidence of P. falciparum infection in HIV-infected and uninfected pregnant women and to reassess the frequency and timing of sulphadoxine-pyrimethamine treatment doses in these women. Late pregnancy re-infections with P. falciparum probably explain the high parasite prevalence at delivery following sulphadoxine-pyrimethamine treatment at 28-34 weeks gestation.

AIDS-Related Opportunistic Infections↗
PubMed1999

The influence of prematurity and low birthweight on transplacental antibody transfer in Sri Lanka.

The influence of gestational age, the neonate's birthweight, and maternal age, weight, height and parity on transplacental antibody transfer was assessed in 141 mothers from Sri Lanka and their neonates. Paired blood samples were collected from the mothers and the umbilical cords of the newborns. The sera separated from these samples were categorized as: preterm but adequate birthweight (< 37 weeks' gestation and birthweight > or = 2500 g); term but low birthweight (> or = 37 weeks' gestation and birthweight < 2500 g); or term and adequate birthweight (> or = 37 weeks' gestation and birthweight > or = 2500 g). Neonatal and maternal sera were assessed, in ELISA, for specific IgG antibodies against measles virus (MeV), herpes simplex virus type-1 (HSV1), respiratory syncytial virus (RSV), varicella-zoster virus (VZV), tetanus toxoid (TT), diphtheria toxoid (DT), and Streptococcus pneumoniae (Pn) and Haemophilus influenzae type-b (Hib) capsular antigens. Placental antibody transfer to certain antibody specificities was significantly lower in preterm neonates than term neonates. Thus the ratios between geometric mean cord antibody levels and geometric mean maternal antibody levels (the antibody-transfer ratios) were lower in preterm sera than term sera, for MeV (1.51 v. 2.03; P = 0.03), HSV1 (1.29 v. 1.76; P = 0.04), VZV (0.96 v. 2.50; P = 0.01), TT (1.13 v. 1.33; P = 0.04), DT (1.03 v. 2.39; P = 0.02), Pn (0.68 v. 0.98; P = 0.01) and Hib (0.58 v. 0.98; P = 0.00). Geometric mean levels of antibody to MeV, VZV, TT, DT and Pn were also significantly lower in preterm neonates than term. Compared with the values for 'adequate-birthweight' sera, low birthweight was independently associated with significantly lower levels of antibody transfer, for MeV (with antibody-transfer ratios of 1.51 v. 2.03; P = 0.02), VZV (0.99 v. 2.50; P = 0.03), TT (1.01 v. 1.33; P = 0.04) and DT (1.16 v. 2.39; P = 0.04) and significantly lower levels of antibodies to MeV, HSV1, VZV, TT, DT and Pn in the neonates. Maternal age, weight, height and parity had no independent influence on placental IgG transfer for antibodies to any of the pathogens investigated. These results demonstrate that prematurity and low birthweight may influence the level of maternally acquired immunity in Sri Lankan neonates.

Antibodies, Bacterial↗
PubMed1999

Laryngeal swabs for diagnosing tuberculosis.

The value of smear and culture of laryngeal swabs as a method of confirming pulmonary tuberculosis was investigated in Indian children. A total of 116 children with 'suspected' tuberculosis had a Mantoux test and chest X-ray. Of these, 51 had a positive Mantoux and/or chest X-ray compatible with tuberculosis, and this group had two laryngeal swabs taken on each of 3 consecutive days. The Mantoux test was positive in 37 (73%) of the 51 'probable' cases. Chest X-ray was abnormal in 36 (71%) cases and compatible with tuberculosis in 20 (39.7%). Mycobacterium tuberculosis was cultured from laryngeal swabs in 14 (28%) children and in another three children smears were positive but culture-negative. The overall confirmation rate for tuberculosis was 33%. Laryngeal swabs are a simple method of confirming tuberculosis and may be undertaken in out-patients.

Adolescent↗
PubMed1999

Viral gastroenteritis.

A large number of viruses can be found in the human intestine. Some (bacteriophages) infect the bacteria present as normal flora and others use the gut as a portal of entry. This review examines the virology, pathogenesis, immunology, epidemiology, clinical features, treatment and prevention of the viral enteropathogens. Rotavirus is undoubtedly the most important, causing an estimated 800,000 deaths each year, especially in developing countries. Recently, an oral live quadrivalent rhesus rotavirus vaccine has been licensed for use in the USA. It has great potential but there are a number of hurdles to be overcome before it can be given to infants in developing countries. Molecular techniques are revolutionizing our understanding of rotavirus pathogenesis, and the tremendous diversity of Caliciviridae and Astroviridae, as well as producing new diagnostic techniques and vaccines.

Journal Article↗
PubMed1999

Nitric oxide production in meningococcal disease is directly related to disease severity.

OBJECTIVES: Meningococcal disease is a homogeneous and well-characterized form of sepsis. Cardiovascular collapse is prominent in severe meningococcal disease. Nitric oxide overproduction may be a mediator of cardiovascular collapse. We relate the level of nitric oxide metabolites, nitrates and nitrites, to disease severity in meningococcal disease. DESIGN: Prospective, nonrandomized study. SETTING: Tertiary referral pediatric intensive care unit. PATIENTS: Children admitted with a clinical diagnosis of meningococcal disease. INTERVENTIONS: Blood was sampled from children with meningococcal disease. Disease severity was scored using the Glasgow meningococcal septicemia prognostic score and pediatric risk of mortality score. Plasma nitrates and nitrites were measured in stored plasma using the Greiss reaction after conversion of all the nitrate to nitrite. MEASUREMENTS AND MAIN RESULTS: Twenty-two children were studied. In 19, the final diagnosis was meningococcal disease. Of the 19 children with meningococcal disease, 7 had a Glasgow meningococcal septicemia prognostic score of <8 (mild) and 12 had a Glasgow meningococcal septicemia prognostic score > or = 8 (severe). Three children died, all of these being in the severely affected group. Higher levels of nitrates and nitrites were seen in the more severely affected children (median admission nitrates and nitrites, 27.5 vs. 59.7 nmol/mL; p = 0.063; median peak nitrates and nitrites, 49.9 vs. 114 nmol/mL; p = .01) or those with an increased predicted mortality using pediatric risk of mortality (Spearman's p 0.742; p = .0003). CONCLUSIONS: Higher levels of nitrates and nitrites are seen in sicker children with meningococcal disease.

Child↗
PubMed1999

Admission cortisol and adrenocorticotrophic hormone levels in children with meningococcal disease: evidence of adrenal insufficiency?

OBJECTIVE: To measure admission cortisol and adrenocorticotrophic hormone (ACTH) levels in children with meningococcal disease to try and determine the prevalence of adrenal insufficiency. DESIGN: Prospective observational study. SETTING: Pediatric departments of four hospitals in Merseyside, United Kingdom. PATIENTS: Ninety-six children with meningococcal disease; 29 with hypotension, ten of whom died. MEASUREMENTS AND MAIN RESULTS: Admission cortisol, ACTH, and proinflammatory cytokine levels were measured. Serial cortisol levels also were measured during the first 48 hrs. Significantly lower cortisol levels were found in those who died compared with survivors. Significantly higher ACTH levels also were found in those who died. However, no child had a cortisol level <5 microg/dL (<138 nmol/L) implying definite adrenal insufficiency. Three of 29 children with hypotension had plasma cortisol levels implying possible adrenal insufficiency (<18 microg/dL [<497 nmol/L]), but high ACTH levels were only found in one of those three. Cortisol levels decreased significantly after antibiotic treatment, unless steroid therapy was administered. ACTH levels did not correlate with cortisol or proinflammatory cytokine levels. CONCLUSIONS: Children with meningococcal disease have a wide range of initial plasma cortisol levels, with lower levels found in those who die. Many factors may affect cortisol levels, but adrenal insufficiency is probably uncommon.

Adolescent↗
PubMed1999

Analysis of Salmonella enterica serotype Typhimurium by phage typing, antimicrobial susceptibility and pulsed-field gel electrophoresis.

Three typing methods commonly used for bacteria--phage typing, antimicrobial susceptibility and pulsed-field gel electrophoresis (PFGE)- were used to characterise 64 Salmonella enterica serotype Typhimurium isolates from individual adult patients from Nairobi, Kenya. The isolates encompassed 11 definitive phage types (DTs), which fell into eight PFGE clusters; 31.3% of isolates were either untypable or reacted nonspecifically with the phages used for typing and 26.6% were of DT 56. Plasmids of c. 100 kb were responsible for self-transferable multiresistance among the isolates. Analysis by PFGE and phage type demonstrated that multiresistant Typhimurium strains causing diarrhoea and invasive disease were multiclonal.

Adult↗
PubMed1999

Evidence for the presence in Burkholderia pseudomallei of a type III secretion system-associated gene cluster.

Burkholderia pseudomallei, the causative agent of melioidosis, contains a cluster of putative genes homologous to those encoding HpaP, HrcQ, HrcR, HrcS and HrpV in the plant pathogen Ralstonia solanacearum. In R. solanacearum, these genes form part of a type III secretion-associated pathogenicity island. The order of the genes in B. pseudomallei is directly equivalent to that found in R. solanacearum. The B. pseudomallei proteins share 49.5% (HpaP), 52.6% (HrcQ), 80.0% (HrcR), 72.1% (HrcS) and 46.7% (HrpV) similarity, respectively, with their equivalent R. solanacearum proteins. The presence of type III secretion-associated genes in B. pseudomallei pathogens suggests a possible role for type III secretion systems in the pathogenicity of this organism.

Amino Acid Sequence↗
PubMed1999

Donovanosis.

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Calymmatobacterium↗
PubMed1999

Bordetella bronchiseptica infection in the cat.

Feline Bordetella bronchiseptica infection had received little consideration until recent years when it has been increasingly documented in association with respiratory disease. This article reviews current knowledge on the organism; its epidemiology, pathogenesis, and clinical, diagnostic and therapeutic features.

Animals↗
PubMed1999

Genotype analysis of Escherichia coli strains isolated from children and chickens living in close contact.

Escherichia coli isolates from rectal swabs from 62 chickens and stools from 42 children living in close contact with chickens on the same farms in Kiambu district, Kenya, were compared for their genetic relatedness. Antibiotic susceptibility profiles broadly categorized isolates from the children and from the chickens into two separate clusters: the majority (144; 85.5%) of the E. coli isolates from children were multidrug resistant, while the majority (216; 87.1%) of the E. coli isolates from chickens were either fully susceptible or resistant only to tetracycline. Sixty- and 100- to 110-MDA plasmids were found to encode the transferable resistance to co-trimoxazole and tetracycline. HindIII restriction endonuclease digestion of the 60- and 100- to 110-MDA plasmids produced four distinct patterns for isolates from children and three distinct patterns for isolates from chickens. XbaI digestion of genomic DNA followed by pulsed-field gel electrophoresis (PFGE) analysis produced 14 distinct clusters. There were six distinct PFGE clusters among the isolates from children, while among the isolates from chickens there were seven distinct clusters. Only one PFGE cluster contained isolates from both children and chickens, with the isolates displaying an approximately 60% coefficient of similarity. This study showed that although several different genotypes of E. coli were isolated from children and chickens from the same farms, the E. coli strains from these two sources were distinct.

Animals↗
PubMed1999

Comparison of flagellin genes from clinical and environmental Pseudomonas aeruginosa isolates.

Pseudomonas aeruginosa, an important opportunistic pathogen, was isolated from environmental samples and compared to clinically derived strains. While P. aeruginosa was isolated readily from an experimental mushroom-growing unit, it was found only rarely in other environmental samples. A flagellin gene PCR-restriction fragment length polymorphism analysis of the isolates revealed that environmental and clinical P. aeruginosa strains are not readily distinguishable. The variation in the central regions of the flagellin genes of seven of the isolates was investigated further. The strains used included two strains with type a genes (998 bp), four strains with type b genes (1,258 bp), and one strain, K979, with a novel flagellin gene (2,199 bp). The route by which flagellin gene variation has occurred in P. aeruginosa is discussed.

Agaricales↗
PubMed1999

Effects of staphylococcal enterotoxins on human neutrophil functions and apoptosis.

Staphylococcal enterotoxins have marked effects on the properties of T cells and monocytes and have recently been reported to affect neutrophil function. In this study, we investigated the abilities of staphylococcal enterotoxins A and B and toxic shock syndrome toxin 1 to affect respiratory burst activity and to delay apoptosis in human neutrophils. When cultures containing approximately 97% neutrophils were tested, the toxins all delayed neutrophil apoptosis in a dose-dependent manner and induced the expression of FcgammaRI on the neutrophil cell surface. These effects on apoptosis and expression of FcgammaRI were largely abrogated by the addition of a neutralizing anti-gamma interferon antibody. Similarly, the effects of these toxins on phorbol ester-induced chemiluminescence were decreased after neutralization of gamma interferon. These effects on neutrophil function were mimicked by the addition of conditioned medium from peripheral blood mononuclear cells incubated with the toxins, and again, neutralizing anti-gamma interferon antibodies largely negated the effects. However, when highly purified neutrophils prepared by immunodepletion of T cells and major histocompatibility complex class II-expressing cells were analyzed, the toxins were without effect on apoptosis and FcgammaRI expression, but granulocyte-macrophage colony-stimulating factor and gamma interferon could still delay apoptosis. These data indicate that these toxins have no direct effect on neutrophil apoptosis but can act indirectly via the production of T-cell-derived and monocyte-derived cytokines. It is noteworthy that such effects are detected in neutrophil suspensions containing only 3% contamination with T cells and other mononuclear cells.

Apoptosis↗
PubMed1999

Typing of Salmonella enterica serotype paratyphi C isolates from various countries by plasmid profiles and pulsed-field gel electrophoresis.

Pulsed-field gel electrophoresis (PFGE) of 61 Salmonella enterica serotype Paratyphi C isolates from six countries gave five distinct clusters. Twenty-four isolates from five countries were susceptible to 10 antimicrobials tested and gave similar restriction endonuclease digest patterns of the 38-MDa plasmid. In contrast, plasmid and PFGE profiles of 37 multidrug-resistant isolates from Zaire were different from those from other countries.

Africa, Eastern↗
PubMed1999

Endothelial cell adhesion molecules in meningococcal disease.

BACKGROUND: Endothelial damage is important in meningococcal disease. Cell adhesion molecules, including P selectin, E selectin, and intercellular cell adhesion molecule 1 (ICAM-1), are expressed by activated endothelium and then subsequently shed. METHODS: ICAM-1, P selectin, and E selectin were measured on admission to hospital in children with meningococcal infections. RESULTS: Concentrations of shed cell adhesion molecules are reported for 78 children. Eleven did not have meningococcal disease. Of the 67 with meningococcal disease, 40 had mild disease (Glasgow meningococcal septicaemia prognostic score (GMSPS) < 8) and 27 had severe disease (GMSPS > or = 8). E selectin and ICAM-1 values were higher in those with meningococcal disease. The E selectin values in those with severe disease were higher than in those with mild disease. P selectin concentrations were not altered in meningococcal disease, but those who died had lower concentrations. CONCLUSIONS: Endothelial activation in meningococcal disease is reflected by shed ICAM-1 and E selectin concentrations.

Adolescent↗
PubMed1999

Zoonoses.

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Animals↗