Genetic and biochemical analyses of sensor kinase A in Bacillus subtilis sporulation.

Temporal and spatial regulation of gene expression during endospore formation in Bacillus subtilis prompted us to investigate the molecular mechanisms that coordinate the phosphorelay. We targeted KinA for random mutagenesis. In addition, we constructed KinA-GFP transcriptional fusions for verification, via fluorescence. Four distinct types of sporulation-defective mutants were identified as inactive (no sporulation), hypoactive (low sporulation efficiency), isoactive (same efficiency as wild-type), and hyperactive (high efficiency) mutants. Surprisingly, the beta-galactosidase activity of hyperactive mutants was barely greater than that of the wild-type strain; the only noticeable difference was early synthesis of KinA, which could allow them to activate Spo0A precociously, undergo sporulation earlier, and yield more spores. There was no fluorescence emission by the spore-defective mutant, which confirmed the presence of a truncated KinA (nonsense mutation) in inactive strains; other mutants harbored missense or silent mutations. We determined the nucleotide sequences of KinA mutants and found a conserved C-terminus region; more variability was observed in the N-terminus region, involving the PAS-A and PAS-C domains. We speculate that PAS-A, notwithstanding its ATPase activity, has only a minor role in KinA activity, whereas PAS-B was found to be indispensable. Our results emphasize the importance of temporal coordination of gene expression during the sporulation process and corroborate the necessity of Spo0A phosphorylation by KinA, which stimulates SpoIIG expression. We further propose a novel hypothetical model that purposely dubbed the "C-shaped intertwined model", which requires both homodimerization and spatial proximity between PAS-A and histidine H(405) of two different KinA molecules.

[Fetal distress: Information provided by lactate levels and antioxidant status, compared with the Apgar score]. / Souffrance foetale: pouvoir informant des lactates et du statut antioxydant versus le score d'Apgar.

The multitude of criteria used to assess fetal distress and the subjective character of the Apgar score led us to compare the information it provides with that from measurements of lactate and two principal antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx). We measured plasma lactates, SOD, and GPX from the umbilical cord blood of live-born children whose mothers had had at least three prenatal consultations. The correlation of these measurements with the 5-minute Apgar score was tested with the Spearman correlation coefficient. Lactate levels were correlated with the baby's blood glucose (r=0.212; p=0.0084), and GPx activity (r=0.179; p=0.0061), the Apgar score (r=0.258; p=0.001) and the mother's blood glucose (r=0.167; p=0.035). GPx was correlated not only with the lactate level but also with birth weight (r=0.205; p=0.000) and height (r=0.316; p=0.0056), while SOD was correlated only with the mother's blood glucose (r=0.161; p=0.046). In multivariate analysis, followed by stepwise analysis, lactate was the main variable associated with the Apgar score. It thus seems better able to replace the Apgar score than the antioxidant enzyme levels. GPx was higher in children of high birth weight and may make them better able to combat the free radicals due to anoxia or hypoxia.

Metabolic complications of severe malaria.

Metabolic complications of malaria are increasingly recognized as contributing to severe and fatal malaria. Disorders of carbohydrate metabolism, including hypoglycaemia and lactic acidosis, are amongst the most important markers of disease severity both in adults and children infected with Plasmodium falciparum. Amino acid and lipid metabolism are also altered by malaria. In adults, hypoglycaemia is associated with increased glucose turnover and quinine-induced hyperinsulinaemia, which causes increased peripheral uptake of glucose. Hypoglycaemia in children results from a combination of decreased production and/or increased peripheral uptake of glucose, due to increased anaerobic glycolysis. Patients with severe malaria should be monitored frequently for hypoglycaemia and treated rapidly with intravenous glucose if hypoglycaemia is detected. The most common aetiology of hyperlactataemia in severe malaria is probably increased anaerobic glucose metabolism, caused by generalized microvascular sequestration of parasitized erythrocytes that reduces blood flow to tissues. Several potential treatments for hyperlactataemia have been investigated, but their effect on mortality from severe malaria has not been determined.

Comparison of methods for the rapid laboratory assessment of children with malaria.

Rapid diagnosis and accurate quantification of Plasmodium falciparum parasitemia are important for the management of malaria. The assessment of disease severity also depends on evaluation of metabolic indexes such as blood glucose and lactate concentrations. Here we describe an accurate and rapid alternative to conventional thick film examination (Lambaréné method). We also assess near-patient methods for measuring blood glucose (OneTouch) and lactate (Accusport). The accuracy of the Lambaréné method is similar to that of thin films. Results from the OneTouch glucose meter also are in good agreement with a YSI 2300 reference meter. Overall, the Accusport lactate meter agrees poorly with the YSI 2300 reference meter. However, the sensitivity and specificity to detect hyperlactatemia (blood lactate > or = 5 mmol/L) are 0.94 and 0.98, respectively.

Plasma glutamine and glutamate concentrations in Gabonese children with Plasmodium falciparum infection.

BACKGROUND: Low plasma glutamine levels in critical illness, neonates and burns patients are associated with poor outcome and increased risk of intercurrent infection. AIM: To investigate the relationship between plasma glutamine/glutamate levels and severity/outcome of malaria. DESIGN: Two-hospital prospective study, with both febrile and healthy controls. METHODS: We measured plasma glutamine and glutamate concentrations in 239 Gabonese patients: 145 children with malaria (86 with severe, 36 with moderate and 23 with uncomplicated disease), 42 healthy children, 44 febrile controls and eight healthy adults, and related findings to conventional markers of disease severity such as plasma lactate. RESULTS: Median (IQR) plasma glutamine was lower in uncomplicated falciparum malaria and in moderate malaria than in healthy controls: 353 (287-474) and 379 (293-448) vs. 485 (428-531) micromol/l, respectively; p<0.01 for both malaria groups vs. controls. In contrast, plasma glutamine was within the normal range in those with severe malaria and in febrile control children: 431 (342-525) and 472 (338-547) micromol/l, respectively. Furthermore, plasma glutamine was significantly higher in the children who died with malaria than in survivors: 514 (374-813) (n=12) vs. 399 (316-475) micromol/l (n=133), respectively; p=0.001. There were no significant differences in plasma glutamate concentrations between any of the study groups. DISCUSSION: In severe malaria, there was a positive correlation between plasma glutamine and lactate levels (p=0.009, r=0.281). This correlation may reflect impaired gluconeogenesis. Glutamine supplementation is probably not justified in severe P. falciparum infection.

Recent advances in the fight against leishmaniasis with natural products.

The active compounds obtained from some medicinal plants used traditionally worldwide for the treatment of leishmaniasis are reviewed. Among these active molecules, described in recent literature are quinoline alkaloids such as alkyl-2 quinoline and aryl-2 quinoline from Galipea longiflora, isoquinoline alkaloids such as isoguattouregidine from Guatteria foliosa, indole alkaloids such as conodurine and gabunine from Pescheiera van heurkii, terpenes such as jatrogrossidione from Jatropha grossidentata, acetogenins such as senegalene from Annona senegalensis and lignans such as (+)nyasol from Asparagus africanus. Other natural compounds with antileishmanial activity are coumarins, chalcones, lactones, tetralones and saponins. Some of them are known antiprotozoal natural products. These compounds could be used as templates to discover new and effective drugs against leishmaniasis.

[Selection criteria for the establishment of reference values in tropical zones. Application to specific proteins: C-reactive protein, haptoglobin, transferrin in gabonese children]. / Critères de sélection pour l'établissement des valeurs de référence en zone tropicale. Application aux protéines spécifiques CRP, HPT, TRF chez l'enfant gabonais.

About 220 children (110 boys and 110 girls) aged 18 months to 10 years, 65.9% have been selected from anamnesis, clinical, and biological criteria to produce reference values on specific proteins dependent inflammatory, anemia and hemolysis (C-reactive protein = CRP; Transferrin = TRF and Haptoglobin: HPT). Specimens have been analysed by Nephelometric immuno-chemical method. For the two groups, A1 [18 months-5 years] and A2 [5-10 years], the reference values of the whole study population are reported: CRP (A1 3.35 +/- 3 mg/l: A2 2.40 +/- 2.30 g/l, with a significant difference at Student Fisher "t" test p < 0.03); TRF (A1 4.05 +/- 1.5 g/l; A2 4.50 +/- 1.4 g/l; NS, p > 0.05) HPT (A1 2.55 +/- 2.0 g/l: A2 1.20 +/- 1.10 g/l; S(r) p < 10(-5)). Furthermore, for TRF, HPT we must consider the sex in the results meaning because of significant difference into boys and girls.

[Variation of cholostase enzymes (5'-nucleotidase and alkaline phosphatase) during a specific treatment for malaria in the Gabonese child]. / Variation des enzymes de la cholostase (5'nucléotidase et phosphatase alcaline) au cours d'une thérapeutique curative spécifique du paludisme infection et maladie chez l'enfant Gabonais.

Biological variations of 5'nucleotidase (5'NU) and alkaline phosphatase (AP) in 102 Gabonese children with malaria features (MF) and malaria infection (MI) receiving treatment are reported. [formula: see text] During the therapeutic assay, 5'NU rate decreases faster than AP'S; Fourteen days after the beginning of treatment, difference between AP MF and AP M1 is still significant. Enzymes decrease is an indication of the malaria drugs tolerance (MSP (*)).

[Distribution of glycosylated hemoglobin (HbA1) in an internal medicine service in Gabon]. / Distribution de l'hémoglobine glyquée (HbA1) en médecine interne au Gabon.

Measurement of glycated hemoglobin (HbA1) concentration is commonly recommended to monitor diabetes, but the relevance of this parameter in some black African populations is questionable. To assess the suitability of this test and study factors affecting HbA1 concentration, we measured HbA1 concentration in 297 consecutive patients (185 men and 112 women) hospitalized in the Internal Medicine Department of the Libreville Hospital Center in Gabon. Distribution of HbA1 was asymmetric with a median at 7.2% (IC95: 6.8-7.6%). Metabolic abnormalities associated with diabetes, renal insufficiency, hyper-bilirubinemia and hypertriglyceridemia were not preferentially correlated with a distribution of HbA1 concentration above the normal threshold of 7.5 %. Elevated concentration were observed in 81 patients presenting no abnormalities. These findings was not due ro technical problems, alcohol abuse, or aspirin intake or to congenital hematologic abnormalities that have been documented in Gabon. On the other hand, an increase in glycation secondary to latent infection which is frequent in tropical areas may partially explain these findings. Regardless of the explanation, HbA1 appears to be unsuitable for monitoring diabetes in this population group.

[Types of sugar diabetes encountered in internal medicine in Gabon]. / Typologie des diabètes sucrés rencontrés en medecine interne au Gabon.

In the 108 patients with diabetes (75 men and 33 women between the ages of 15 and 86 years) hospitalized in the Internal Medicine Department of the Libreville Hospital Center between January 1, 1989 and December 31, 1991, 53 were easily classified, 12 being due to alcohol-induced chronic calcific pancreatitis, two to insulin-dependent diabetes, and 39 to non-insulin-dependent diabetes. Fifty-five patients treated with insulin were not immediately classifiable including 11 who were obese and probably should not have required insulin. In the remaining 44 patients who were not overweight, the youngest often presented features comparable to those observed in patients with chronic calcific pancreatitis except with regard to calcification. Most of the older patients were women in whom diagnosis was coincidental. These findings indicate that authentic insulin-dependent diabetes is uncommon, that non-insulin-dependent diabetes are frequent, and that the endocrine pancreas is particularly susceptible to alcohol abuse.

[Lipid profile during specific malaria therapy in Gabonese children]. / Profil lipidique au cours d'une thérapeutique curative spécifique du paludisme maladie chez l'enfant gabonais.

We report specific dyslipidemia in Gabonese children aged 18 months to 4 years old treated with Halfan for malaria. This is observed in addition to the hypoglycemia typically associated with malaria. C-HDL (high density lipoprotein) fell on day 0 (D0), then increased during the treatment. Triglycerides (TG), total cholesterol (TC) and non-esterified fatty acids (NEFA) rose on D0. CT continued to rise evenly throughout the treatment, whereas TG declined. The differences with respect to normal values are significantly different as assessed by the Student test. We report metabolic variation and tolerance to Halfan.

Protein C activity in Gabonese children with sickle cell disease.

Protein C levels were determined in 40 Gabonese children with sickle cell disease, in the steady state and during vasoocclusive crisis. In comparison with 40 healthy controls matched for age and sex, there was a significant decrease in protein C activity in the patients, although no difference was found between protein C levels in the steady state and during crisis.

Antiplasmodial activity of Uvaria klaineana.

Crude extracts of Uvaria klaineana Engler and Diels (Annonaceae) stems showed in vitro activity against chloroquine-resistant K1 strain of Plasmodium falciparum. The most active extract was the basic dichloromethane extract containing crude alkaloids (IC50 = 3.55 microg/mL). The bioassay-guided fractionation of this extract led to the isolation of the major alkaloid crotsparine (1) which showed an antiplasmodial activity against the chloroquine-sensitive Thai strain of P. falciparum and the chloroquine-resistant K1 and FcB1 strains of P. falciparum. Two minor alkaloids were also identified as crotonosine (2) and zenkerine (3). Their structures were elucidated using 2D-NMR techniques.

Acaricidal activity of Uvaria versicolor and Uvaria Klaineana (Annonaceae).

Three Uvaria species, namely U. klaineana, U. mocoli and U. versicolor were tested in vitro against Dermatophagoides pteronyssinus, the European house dust mite. The most active extracts were the Uvaria versicolor stems crude methanol and hexane extracts with EC(50) values of 0.095 g/m(2 )and 0.12 g/m(2), respectively. The bioassay-guided fractionation of the hexane extract led to the isolation of benzyl benzoate (1). which exhibited an EC(50) value of 0.045 g/m(2). A new fl avanone, versuvanone (2). and the known oxoaporphine liriodenine (3). were also isolated from this species and showed EC(50) values > 1.5 g/m(2). A weak acaricidal activity (0.85 g/m(2)) was observed for the dichloromethane extract of Uvaria klaineana, due to the presence of benzyl benzoate. Uvaria mocoli was inactive. The structures of compounds were elucidated using 2D-NMR techniques.