Hyponatraemia: biochemical and clinical perspectives.
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Hyponatraemia is a common bio-chemical abnormality, occurring in about 15% of hospital inpatients. It is often associated with severe illness and relatively poor outcome. Pathophysiologically, hyponatraemia may be spurious, dilutional, depletional or redistributional. Particularly difficult causes and concepts of hyponatraemia are the syndrome of inappropriate antidiuresis and the sick cell syndrome, which are discussed here in detail. Therapy should always be targeted at the underlying disease process. 'Hyponatraemic symptoms' are of doubtful importance, and may be more related to water overload and/or the causative disease, than to hyponatraemia per se. Artificial elevation of plasma sodium by saline infusion carries the risk of induction of osmotic demyelination (central pontine myelinolysis). (+info)
Malaria infection and morbidity in infants in relation to genetic polymorphisms in Tanzania.
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To investigate the effects of host polymorphisms on malaria morbidity and infection, the frequency distributions of TNF alpha promotor gene and sickle cell trait were studied in infants in an area highly endemic for Plasmodium falciparum transmission in Tanzania. Differences in parasite prevalence, density, febrile episodes with and without parasitaemia, PCV levels and the frequencies of different MSP-2 parasite infections were assessed by genotype. The frequency of the TNF alpha promotor allele 2 was 0.09, and the trait was in Hardy-Weinberg equilibrium. There were no differences in malariametric indices between infants with the normal TNF alpha promoter gene and those who were heterozygous for this trait. Infants heterozygous for the TNF alpha promotor gene appeared to have fewer febrile episodes when they were free of parasites. The two infants homozygous for the TNF alpha promoter allele 2 had both a much higher incidence of fever, independently of parasitaemia, than the average for the other genotypes. The frequency of the sickle cell allele S was 0.06 and the trait was also in Hardy-Weinberg equilibrium. Infants heterozygous for the sickle cell trait had significantly lower parasite densities, but similar prevalence, and MSP-2 infections compared to infants with normal haemoglobin. PCV levels, and the incidence of febrile episodes both with and without parasitaemia were also similar. In contrast to the sickle cell trait, the TNF alpha promotor polymorphism appeared not to have any protective effect on malaria in this study, and its importance in other unspecified fever-causing diseases in this population needs further investigation. (+info)
Longitudinal study of Plasmodium falciparum infection and immune responses in infants with or without the sickle cell trait.
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BACKGROUND: Individuals may be homozygous (SS) or heterozygous (AS) sickle cell gene carriers or have normal adult haemoglobin (AA). Haemoglobin S could have a protective role against malaria but evidence is sparse and the operating mechanisms are poorly known. METHODS: We followed two cohorts of children. The first was enrolled at birth (156 newborn babies) and the second at 24-36 months old (84 children). Both cohorts were followed for 30 months; monthly for parasitological data and half yearly for immunological data. RESULTS: In the first cohort, 22%, and in the second 13% of children were AS. Whatever their age parasite prevalence rates were similar in AA and AS individuals. Mean parasite densities increased less rapidly with age in AS than in AA children, and were significantly lower in AS than in AA children >48 months old. The AA children tended to be more often admitted to hospital than AS children (22% versus 11%, NS). Both anti-Plasmodium falciparum and anti-Pfl55/RESA antibody rates increased more rapidly in AA than in AS children. Conversely, the prevalence rate of cellular responders to the Pfl55/RESA antigen was similar in AA and AS children during the first 2 years of life, then it was higher in AS than in AA children. CONCLUSIONS: Sickle cell trait related antimalarial protection varies with age. The role of the modifications of the specific immune response to P. falciparum in explaining the protection of AS children against malaria is discussed. (+info)
Pallister-Hall syndrome: clinical and MR features.
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A 4-month-old boy with polydactyly and bifid epiglottis was found to have a large sellar and suprasellar mass. When the diagnosis of Pallister-Hall syndrome was made, conservative management was elected. When the patient was 2 years old, the tumor had grown proportionally with the patient, and he was developing appropriately. Although rare, this entity is important to recognize not only for clinical diagnosis but also for appropriate management and genetic counseling. (+info)
Effectiveness of pneumococcal polysaccharide vaccine for preschool-age children with chronic disease.
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To estimate the effectiveness of pneumococcal polysaccharide vaccine, we serotyped isolates submitted to the Pneumococcal Sentinel Surveillance System from 1984 to 1996 from 48 vaccinated and 125 unvaccinated children 2 to 5 years of age. Effectiveness against invasive disease caused by serotypes included in the vaccine was 63%. Effectiveness against serotypes in the polysaccharide vaccine but not in a proposed seven-valent protein conjugate vaccine was 94%. (+info)
The role of red blood cell polymorphisms in resistance and susceptibility to malaria.
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In regions highly endemic for Plasmodium falciparum malaria, red cell polymorphisms that confer resistance to severe disease are widespread. Sickle cell trait, alpha-thalassemia, glucose-6-phosphate dehydrogenase deficiency, and blood groups were determined in 100 children from Gabon with severe malaria who were matched with 100 children with mild malaria and followed up for evaluation of reinfections. The sickle cell trait was significantly associated with mild malaria and blood group A with severe malaria. During follow-up, the original severe cases had significantly higher rates of reinfection than the original mild cases, with higher parasitemia and lower hematocrit values. Incidence rates did not differ in the context of erythrocyte polymorphisms, but patients with sickle cell trait presented with markedly lower levels of parasitemia than those without. Thus, the severity of malaria is partly determined by the presence of blood group A and the sickle cell trait. The different presentation of reinfections in severe versus mild cases probably reflects different susceptibility to malaria. (+info)
Human genetic factors related to susceptibility to mild malaria in Gabon.
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Several human genetic factors, including red blood cell polymorphisms (ABO blood group, sickle-cell trait, G6PD deficiency) as well as point mutations in the mannose binding protein (MBP) and in the promoter regions of both the TNF-alpha and NOS2 genes, influence the severity of disease due to infection with Plasmodium falciparum. We assessed their impact on mild P. falciparum malaria, as part of a longitudinal investigation of clinical, parasitological and immunological parameters in a cohort of 300 Gabonese schoolchildren. We found the following frequencies: blood group O (0.54), sickle-cell trait (0.23), G6PD deficiency (0.09), MBP gene mutations (0.34), TNF-alpha promoter mutations (at positions -238: 0.17 and -308: 0.22) and NOS2 promoter mutation (0.18). Blood group O or hemoglobin AA were associated with protection against higher parasitemia. Girls with normal G6PD enzyme activity were protected against clinical malaria attacks. In addition, we demonstrated for the first time that the mutation at position -238 of the gene coding for the promoter region of TNF-alpha was positively correlated with the level of the antibody response specific for epitopes of the antigens MSA-2 and RAP-1 of P. falciparum. (+info)
Social information processing and magnetic resonance imaging in children with sickle cell disease.
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OBJECTIVE: To examine social information processing, social skills, and adjustment difficulties in children with sickle cell disease (SCD) as rated by caregivers, teachers, and the children themselves. Children were classified in two groups: cerebral vascular accidents (CVA) (n = 21) or without central nervous system (CNS) pathology (n = 20) on magnetic resonance imaging (MRI). Both groups had HbSS SCD. We compared these two groups and a third group of 11 children who had a milder type of SCD (HbSC). METHODS: Participants referred for evaluation of learning and behavior problems were administered MRIs to ascertain the presence of pathology and a series of measures designed to assess nonverbal emotional decoding abilities and ratings of social emotional functioning. RESULTS: Children with CVA displayed more errors on tasks of facial and vocal emotional decoding than did comparison controls without CVA. CONCLUSIONS: Acquired neurological impairments in children with SCD seemed to be associated with difficulties in the decoding of emotions of other children and adults. We recommend that future research integrate neuropsychological and psychosocial research programs for pediatric chronic illness groups. (+info)