In vitro antibacterial activity and acute toxicity studies of aqueous-methanol extract of Sida rhombifolia Linn. (Malvaceae)

<p>Abstract</p> <p>Background</p> <p>Many bacteria among the Enterobacteria family are involved in infectious diseases and diarrhoea. Most of these bacteria become resistant to the most commonly used synthetic drugs in Cameroon. Natural substances seem to be an alternative to this problem. Thus the aim of this research was to investigate the <it>in vitro </it>antibacterial activity of the methanol and aqueous-methanol extracts of <it>Sida rhombifolia </it>Linn (Malvaceae) against seven pathogenic bacteria involved in diarrhoea. Acute toxicity of the most active extract was determined and major bioactive components were screened.</p> <p>Methods</p> <p>The agar disc diffusion and the agar dilution method were used for the determination of inhibition diameters and the Minimum Inhibitory Concentration (MICs) respectively. The acute toxicity study was performed according WHO protocol.</p> <p>Results</p> <p>The aqueous-methanol extract (1v:4v) was the most active with diameters of inhibition zones ranging from 8.7 - 23.6 mm, however at 200 μg/dic this activity was relatively weak compared to gentamycin. The MICs of the aqueous-methanol extract (1v:4v) varied from 49.40 to 78.30 μg/ml. <it>Salmonella dysenteriae </it>was the most sensitive (49.40 μg/ml). For the acute toxicity study, no deaths of rats were recorded. However, significant increase of some biochemical parameters such as aspartate amino-transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and creatinine (CRT) were found. The phytochemical analysis of the aqueous methanol extract indicated the presence of tannins, polyphenols, alkaloids, glycosides, flavonoids and saponins</p> <p>Conclusion</p> <p>The results showed that the aqueous-methanol extract of <it>S. rhombifolia </it>exhibited moderate antibacterial activity. Some toxic effects were found when rats received more than 8 g/kg bw of extract.</p> <p><it>Antibacterial; Enterobacteria; Acute toxicity; Phytochemical analysis</it></p

Does dietary tocopherol level affect fatty acid metabolism in fish?

Fish are a rich source of the n-3 polyunsaturated fatty acids (PUFA), particularly the highly unsaturated fatty acids (HUFA), eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 22:6n-3) acids, which are vital constituents for cell membrane structure and function, but which are also highly susceptible to attack by oxygen and other organic radicals. Resultant damage to PUFA in membrane phospholipids can have serious consequences for cell membrane structure and function, with potential pathological effects on cells and tissues. Physiological antioxidant protection involves both endogenous components, such as free radical scavenging enzymes, and exogenous dietary micronutrients including tocopherols and tocotrienols, the vitamin E-type compounds, widely regarded as the primary lipid soluble antioxidants. The antioxidant activities of tocopherols are imparted by their ability to donate their phenolic hydrogen atoms to lipid (fatty acid) free radicals resulting in the stabilisation of the latter and the termination of the lipid peroxidation chain reaction. However, tocopherols can also prevent PUFA peroxidation by acting as quenchers of singlet oxygen. Recent studies on marine fish have shown correlations between dietary and tissue PUFA/tocopherol ratios and incidence of lipid peroxidation as indicated by the levels of TBARS and isoprostanes. These studies also showed that feeding diets containing oxidised oil significantly affected the activities of liver antioxidant defence enzymes and that dietary tocopherol partially attenuated these effects. However, there is evidence that dietary tocopherols can affect fatty acid metabolism in other ways. An increase in membrane PUFA was observed in rats deficient in vitamin E. This was suggested to be due to over production of PUFA arising from increased activity of the desaturation/elongation mechanisms responsible for the synthesis of PUFA. Consistent with this, increased desaturation of 18:3n-3 and 20:5n-3 in hepatocytes from salmon fed diets deficient in tocopherol and/or astaxanthin has been observed. Although the mechanism is unclear, tocopherols may influence biosynthesis of n-3PUFA through alteration of cellular oxidation potential or “peroxide tone”

Molecular biology of the blood-brain and the blood-cerebrospinal fluid barriers: similarities and differences

Efficient processing of information by the central nervous system (CNS) represents an important evolutionary advantage. Thus, homeostatic mechanisms have developed that provide appropriate circumstances for neuronal signaling, including a highly controlled and stable microenvironment. To provide such a milieu for neurons, extracellular fluids of the CNS are separated from the changeable environment of blood at three major interfaces: at the brain capillaries by the blood-brain barrier (BBB), which is localized at the level of the endothelial cells and separates brain interstitial fluid (ISF) from blood; at the epithelial layer of four choroid plexuses, the blood-cerebrospinal fluid (CSF) barrier (BCSFB), which separates CSF from the CP ISF, and at the arachnoid barrier. The two barriers that represent the largest interface between blood and brain extracellular fluids, the BBB and the BCSFB, prevent the free paracellular diffusion of polar molecules by complex morphological features, including tight junctions (TJs) that interconnect the endothelial and epithelial cells, respectively. The first part of this review focuses on the molecular biology of TJs and adherens junctions in the brain capillary endothelial cells and in the CP epithelial cells. However, normal function of the CNS depends on a constant supply of essential molecules, like glucose and amino acids from the blood, exchange of electrolytes between brain extracellular fluids and blood, as well as on efficient removal of metabolic waste products and excess neurotransmitters from the brain ISF. Therefore, a number of specific transport proteins are expressed in brain capillary endothelial cells and CP epithelial cells that provide transport of nutrients and ions into the CNS and removal of waste products and ions from the CSF. The second part of this review concentrates on the molecular biology of various solute carrier (SLC) transport proteins at those two barriers and underlines differences in their expression between the two barriers. Also, many blood-borne molecules and xenobiotics can diffuse into brain ISF and then into neuronal membranes due to their physicochemical properties. Entry of these compounds could be detrimental for neural transmission and signalling. Thus, BBB and BCSFB express transport proteins that actively restrict entry of lipophilic and amphipathic substances from blood and/or remove those molecules from the brain extracellular fluids. The third part of this review concentrates on the molecular biology of ATP-binding cassette (ABC)-transporters and those SLC transporters that are involved in efflux transport of xenobiotics, their expression at the BBB and BCSFB and differences in expression in the two major blood-brain interfaces. In addition, transport and diffusion of ions by the BBB and CP epithelium are involved in the formation of fluid, the ISF and CSF, respectively, so the last part of this review discusses molecular biology of ion transporters/exchangers and ion channels in the brain endothelial and CP epithelial cells

Le Calendrier de Vaccination Infantile: Mise a Jour

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Accelerated Death Kinetics of Aspergillus niger Spores under High-Pressure Carbonation

The death kinetics of Aspergillus niger spores under high-pressure carbonation were investigated with respect to the concentration of dissolved CO(2) (dCO(2)) and treatment temperature. All of the inactivation followed first-order death kinetics. The D value (decimal reduction time, or the time required for a 1-log-cycle reduction in the microbial population) in the saline carbonated at 10 MPa was 0.16 min at 52°C. The log D values were linearly related to the treatment temperature and the concentration of dCO(2), but a significant interaction was observed between them

Diagnostic markers of infection in curret pediatric practice

Diagnostic markers are useful biological indicators of infection. Confirmatory diagnostic tests may take time, so biologic markers are necessary to have a rapid indication of the infection status so that antibiotherapy can be rapidly instituted. They are also useful to follow-up the course of the infection with treatment. Some tests as the hematological profile indices (total leukocyte count, total neutrophil count, immature/total neutrophil ratio, platelet count and erythrocyte sedimentation rate) and some acute phase proteins as C-reactive protein are readily available in most clinical settings. Others as procalcitonin chemokines, cytokines, adhesion molecules, cell surface markers and polymerase chain reaction are expensive and available only in specialised research laboratories. Optimal benefit can be obtained from rational use of currently available markers either by multiple marker assays or serial measurements which increase sensitivity and specificity. What ever the clinical setting the decision to institute or stop antimicrobial therapy will depend on the clinical situation of the child, and these markers only confirming the clinical decision. We hope that procalcitonin measurement with a higher sensitivity and specificity than haematological profile indices, C- reactive protein and erythrocyte sedimentation rate, be readily available in low-resource settings at low cost to improve management of sick neonates.Les marqueurs biologiques sont des indicateurs utiles pour le diagnostic de l'infection. Le diagnostic de confirmation de certaines infections étant souvent retardé, les marqueurs biologiques constituent un outil nécessaire non seulement pour le diagnostic de présomption et la prise en charge thérapeutique précoce, mais aussi dans le suivi de l'évolution du traitement. Certains marqueurs comme les tests hématologiques (leucocytes totaux, neutrophiles totaux, rapport neutrophiles immatures/ totaux, taux de plaquettes et la vitesse de sédimentation), et les protéines de la phase aiguë de l'inflammation comme la protéine C-réactive sont souvent disponibles et utilisés dans la plupart des institutions sanitaires. Les autres comme la procalcitonine, les chemokines, les cytokines, les molécules d'adhésion et l'amplification par polymérisation en chaîne sont coûteux et ne sont disponibles que dans certains laboratoires de recherche. Un bénéfice optimal peut être obtenu par une utilisation rationnelle des marqueurs disponibles, soit en utilisant plusieurs marqueurs ou des dosages séquentiels qui augmenteront la sensibilité et la spécificité. Quelque soit le cas, la décision d'instituer ou d'arrêter l'antibiothérapie dépendra de la situation clinique de l'enfant et les marqueurs ne confirmeront que la décision clinique. Nous espérons que le dosage de procalcitonin qui a une sensibilité et une spécificité supérieure aux indices hématologiques, la protéine C- réactive et la vitesse de sédimentation soit disponible à moindre coût dans les pays en voie de développement pour améliorer la prise en charge des nouveaux-nés malades. Keywords: Diagnostic markers-Infection-Children.Clinics in Mother and Child Health Vol. 4 (1) 2007: pp. 671-67

Stroke in sickle cell anemia: New concepts in diagnosis and management

Stroke is a devastating and potentially fatal complication of sickle cell disease. The highest incidence of cerebrovascular disease is in the first 10 years and especially between 2 to 5 years. Two types of stroke occur in these patients – infarctive and hemorrhagic strokes. While infarctive strokes occur frequently in children, hemorrhagic strokes occur mostly in adults. Associated risk factors include: history of transient ischemic attacks, association of acute chest syndrome, severe anemia, a high leukocyte count and a genetic susceptibility. In the presence of stroke, the main investigations are computed tomography and magnetic resonance imaging. Primary prevention is the main axis of management. This consists of transcranial Doppler ultrasonography screening in sicklers as from 2 years of age every 6 months, and patients with abnormal velocities of or greater than 200cm/seconds should receive chronic transfusion therapy every 3 – 4 weeks. The decision to initiate transfusion should be based on careful consideration of the risks and benefits. This with the aim of averting the inherent motor and neuropsychogical impairments from stroke.L'accident vasculaire cérébral (AVC) chez le drépanocytaire est une complication grave greffée d'une mortalité élevée.L'incidence la plus élevée est dans la première décennie de la vie surtout entre 2 et 5 ans. Il existe deux types d'AVC chez le drépanocytaire – ischémique et hémorragique. Les accidents ischémiques surviennent surtout chez les enfants, et les accidents hémorragiques surtout chez les adultes. Les facteurs prédisposants sont : l'antécédent d'accident ischémique transitoire, le syndrome thoracique aiguë, l'anémie sévère, la leucocytose et une susceptibilité génétique. En présence d'AVC, les principaux examens sont : le scanner cérébral, et l'imagerie par résonance magnétique. La prévention primaire reste le principal axe du traitement. Ceci consiste à pratiquer un Doppler transcrânien chez les drépanocytaires dès l'âge de 2 ans et tous les 6 mois et les patients ayant des vitesses moyennes des artères du polygone de Willis supérieur ou égale à 200 cm/seconde bénéficieront d'un programme de transfusion périodique toutes les 3-4 semaines. La décision d'initier la transfusion ne doit être prise qu'après avoir évalué les risques et bénéfices des transfusions. Cette prise en charge permet de prévenir les séquelles motrices et neuropsychiques liées à cette affection. Keywords: Stroke - Sickle cell anemia - Risk factors - Clinical presentation - Diagnosis - Management Clinics in Mother and Child Health Vol. 3(2) 2006: pp. 585-59