Antimicrobial effect of Dinoponera quadriceps (Hymenoptera: Formicidae) venom against Staphylococcus aureus strains.

AIMS: Dinoponera quadriceps venom (DqV) was examined to evaluate the antibacterial activity and its bactericidal action mechanism against Staphylococcus aureus. METHODS AND RESULTS: DqV was tested against a standard strain of methicillin-sensitive Staphylococcus aureus (MSSA), Staph. aureus ATCC 6538P and two standard strains of methicillin-resistant Staphylococcus aureus (MRSA), Staph. aureus ATCC 33591 and Staph. aureus CCBH 5330. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), the rate of kill and pH sensitivity of the DqV were determined by microdilution tests. Bactericidal and inhibitory concentrations of DqV were tested to check its action on Staph. aureus membrane permeability and cell morphology. The MIC and MBC of DqV were 6·25 and 12·5 µg ml(-1) for Staph. aureus ATCC 6538P, 12·5 and 50 µg ml(-1) for Staph. aureus CCBH 5330 and 100 and 100 µg ml(-1) for Staph. aureus ATCC 33591, respectively. Complete bacterial growth inhibition was observed after 4 h of incubation with the MBC of DqV. A lowest MIC was observed in alkaline pH. Alteration in membrane permeability was observed through the increase in crystal violet uptake, genetic material release and morphology in atomic force microscopy. CONCLUSIONS: The results suggest antibacterial activity of DqV against Staph. aureus and that the venom acts in the cell membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: Alteration in membrane permeability may be associated with the antimicrobial activity of hymenopteran venoms.

Renal- and calcium-dependent vascular effects of Polybia paulista wasp venom

In the present study, the effects of Polybia paulista venom (PPV) on renal and vascular tissues were investigated. Isolated kidneys perfused with PPV (1 and 3 ìg/mL) had increased perfusion pressure, renal vascular resistance, urinary flow, and glomerular filtration rate; and reduced sodium tubular transport. Histological evaluation demonstrated deposits of proteins in Bowman's space and tubular lumen, and focal areas of necrosis. The venom promoted a cytotoxic effect on Madin-Darby canine kidney (MDCK) cells. A significant increase in lactic dehydrogenase levels was observed in response to venom exposure. In isolated mesenteric vascular beds, pressure and vascular resistance augmented in a dose-dependent manner. PPV increased the contractility of aortic rings maintained under basal tension. This contractile response was inhibited when preparations were maintained in Ca2+-free medium. Likewise, verapamil, a voltage-gated calcium channel blocker, also inhibited the contractile response. In this study, phentolamine, a blocker of á-adrenergic receptor blocker, significantly reduced the contractile effect of PPV in the aortic ring. In conclusion, PPV produced nephrotoxicity, which suggests a direct effect on necrotic cellular death in renal tubule cells. The vascular contractile effect of PPV appears to involve calcium influx through voltage-gated calcium channels via adrenergic regulation.

Renal and vascular effects of Crotalus durissus cumanensis venom and its crotoxin fraction

In this study, we evaluated the actions of Crotalus durissus cumanensis venom (CDCmV), and its crotoxin (Crtx) fraction, on renal and vascular functions in Wistar rats. In isolated perfused kidneys, CDCmV (10 µg/mL) significantly increased the perfusion pressure (PP) from 110.7 ± 2.4 to 125.3 ± 2.8 mmHg after 30 minutes. This effect was accompanied by an increased renal vascular resistance (RVR) from 5.4 ± 0.1 to 6.2 ± 0.2 mmHg/mL.g-1.min-1. We observed decreases in urinary flow (UF) from 0.13 ± 0.01 to 0.05 ± 001 mL.g-1.min-1 and glomerular filtration rate (GFR) from 0.66 ± 0.06 to 0.18 ± 0.02 mL.g-1.min-1. Crtx did not change PP or RVR, but diminished GFR (from 0.65 ± 0.05 to 0.26 ± 003 mL.g-1.min-1) and UF (from 0.11 ± 0.008 to 0.09 ± 0.008 mL.g-1.min-1). Both CDCmV and Crtx reduced the percentage of tubular transport of sodium, chloride and potassium. The cytotoxicity of these substances against MDCK cells was tested by the MTT method: only CDCmV caused a decrease in the cell viability with an IC50 of 5.4 µg/mL. In endothelium-intact isolated aortic rings, CDCmV (0.1 to 30 µg/mL) increased the sustained phenylephrine-induced contraction to a value of 130.0 ± 6.6 percent of its corresponding control, but showed a relaxant effect in endothelium-denuded preparations. Similar results were observed in aortic rings contracted with potassium (40 mM). Crtx was ineffective in aortic ring assays. Thus, it is reasonable to suggest that the renal effects induced by the CDCmV may be due to its influence on the endothelium's ability to release factors that can alter the contractile behavior of vascular smooth muscle. In conclusion, CDCmV is toxic to kidney cells. It changes parameters of the renal function including the glomerular filtration rate, renal vascular resistance and tubular transport. The actions induced by CDCmV also involve endothelium-dependent vasoactive properties. Their effects may be only partially attributed to Crtx.

Antimicrobial activity of an L-amino acid oxidase isolated from Bothrops leucurus snake venom

Some snake venom proteins present enzymatic activities, such as L-amino acid oxidase (LAAO). The aim of this paper was to investigate the effect of Bothrops leucurus total venom (BleuTV) and its fraction LAAO (BleuLAAO) on bacteria, yeast, and promastigote forms of Leishmania amazonensis and Leishmania chagasi, and epimastigote forms of Trypanosoma cruzi. BleuTV was isolated with a Protein Pack 5PW® (Waters Corporation, USA), and several fractions were obtained. BleuLAAO was purified to high molecular homogeneity, and its N-terminal amino acid sequence shared a high degree of amino acid conservation with other LAAOs. BleuTV inhibited Staphylococcus aureus growth in a dose-dependent manner, with a minimum inhibitory concentration (MIC) of 25 ìg/mL, which corresponded to its minimum lethal concentration (MLC). BleuTV also inhibited the growth of promastigote forms of L. chagasi and L. amazonensis, with respective IC50 values of 1.94 ìg/mL and 5.49 ìg/mL. Furthermore, it repressed T. cruzi growth with an IC50 of 1.14 ìg/mL. However, BleuLAAO did not inhibit the growth of the microorganisms studied and was not toxic to macrophages. BleuTV had low toxicity against macrophages at the concentrations studied. In conclusion, whole venom from Bothrops leucurus inhibited the growth of some microorganisms, including S. aureus, Leishmania sp., and T. cruzi.(AU)

Antimicrobial activity of an L-amino acid oxidase isolated from Bothrops leucurus snake venom

Some snake venom proteins present enzymatic activities, such as L-amino acid oxidase (LAAO). The aim of this paper was to investigate the effect of Bothrops leucurus total venom (BleuTV) and its fraction LAAO (BleuLAAO) on bacteria, yeast, and promastigote forms of Leishmania amazonensis and Leishmania chagasi, and epimastigote forms of Trypanosoma cruzi. BleuTV was isolated with a Protein Pack 5PW® (Waters Corporation, USA), and several fractions were obtained. BleuLAAO was purified to high molecular homogeneity, and its N-terminal amino acid sequence shared a high degree of amino acid conservation with other LAAOs. BleuTV inhibited Staphylococcus aureus growth in a dose-dependent manner, with a minimum inhibitory concentration (MIC) of 25 ìg/mL, which corresponded to its minimum lethal concentration (MLC). BleuTV also inhibited the growth of promastigote forms of L. chagasi and L. amazonensis, with respective IC50 values of 1.94 ìg/mL and 5.49 ìg/mL. Furthermore, it repressed T. cruzi growth with an IC50 of 1.14 ìg/mL. However, BleuLAAO did not inhibit the growth of the microorganisms studied and was not toxic to macrophages. BleuTV had low toxicity against macrophages at the concentrations studied. In conclusion, whole venom from Bothrops leucurus inhibited the growth of some microorganisms, including S. aureus, Leishmania sp., and T. cruzi.

Eficiência do óleo de nim (azadirachta indica a. juss) no controle de brevicoryne brassicae (linnaeus, 1758) e myzus persicae (sulzer, 1776) (hemiptera: aphididae) em couve-manteiga brassica oleracea linnaeus var. acephala

ABSTRACT The neem plant (Azadirachta indica A. Juss) possesses insecticide properties and has been used widely as an alternative in the control of a number of pest arthropods. As the aphids Brevicoryne brassicae (Linnaeus, 1758) and Myzus persicae (Sulzer, 1776) are important pests in the cultivation of kale, the present study was aimed to evaluate the efficiency of the extract of neem oil for the control of these insects. Ten adult aphids were put into Petri dishes 5 cm in diameter, containing leaf disk of kale on an agar gel layer. The insects were given the substances by means of a hand sprayer at the concentrations of 0.25%; 0.50%; 0.75%; 1.0% and 2.0%. As positive controls, 0.028% imidacloprid was utilized, while the negative control was only distilled water. The Petri dishes were maintained in an climatic chamber at 25 ± 2º C, relative humidity of 70 ± 10% and 12-hour photophase. The evaluations of mortality of the aphids and of the number of surviving nymphs from the treated adults were carried out at 1h, 6h, 12h, 24h, 48h and 72h after spraying of the compounds on the insects. Neem oil at all the tested concentrations is efficient in the control of B. brassicae, but for M. persicae it is toxic only at the concentrations of 1% and 2%.

RESUMO A planta de Nim (Azadirachta indica A. Juss) possui propriedades inseticidas e vem sendo amplamente utilizada como alternativa no controle de muitos artrópodes-praga. Sendo os pulgões Brevicoryne brassicae (Linnaeus, 1758) e Myzus persicae (Sulzer, 1776) pragas importantes para a cultura da couve-manteiga, avaliou-se neste trabalho a eficiência do extrato de óleo de Nim para o controle desses insetos. Dez pulgões adultos foram colocados em placas de Petri de 5 cm de diâmetro, contendo discos foliares de couve sobre uma camada de ágar-gel. Os insetos receberam as substâncias por meio de pulverizador manual, nas concentrações de 0,25%; 0,5%; 0,75%; 1,0% e 2,0%. Como testemunha positiva, utilizou-se imidaclopride 0,028% e negativa, apenas água destilada. As placas de Petri foram mantidas em câmara climatizada a 25 ± 2º C, umidade relativa de 70 ± 10% e fotofase de 12 horas. As avaliações da mortalidade dos pulgões e do número de ninfas sobreviventes oriundas de adultos tratados foram realizadas a 1h, 6h, 12h, 24h, 48h e 72h, após a pulverização dos compostos sobre os insetos. O óleo de Nim em todas as concentrações testadas foi eficiente no controle de B. brassicae, e para M. persicae somente nas concentrações de 1% e 2%.

Prothrombotic disorders in children with moyamoya syndrome.

BACKGROUND AND PURPOSE: Moyamoya syndrome is an uncommon chronic occlusive cerebrovascular disease in children. The origin of moyamoya syndrome remains undetermined. The role of the prothrombotic disorders contributing to its pathogenesis has not been completely elucidated. The purpose of this study was to determine the frequency of prothrombotic disorders in a pediatric population with moyamoya syndrome. METHODS: From May 1992 to April 2000, a prospective study of 10 consecutive children with moyamoya syndrome was carried out at a single center. Evaluation included the following assays: protein C, protein S, antithrombin, plasminogen, activated protein C resistance, factor V Leiden, and prothrombin gene mutations. Lupus anticoagulant, anticardiolipin antibodies, and anti-beta(2)-glycoprotein I antibodies assays were also performed. The clinical characteristics, underlying diseases, family history of thrombosis, radiological findings, treatment, and outcome were also recorded. RESULTS: In our series, prothrombotic disorders were detected in 4 patients (40%). Inherited protein S deficiency was found in 1 patient; lupus anticoagulant and anticardiolipin antibodies were detected in the remaining 3 patients. One presented persistent lupus anticoagulant for 2.7 years until his death. In the case of the other 2 patients, 1 has maintained lupus anticoagulant for 9 months, whereas the other has kept anticardiolipin/anti-beta(2)-glycoprotein I antibodies for 10 months. CONCLUSIONS: We report the hemostatic data of the largest prospective pediatric study carried out at a single center in the western hemisphere. In 4 patients (40%), a prothrombotic disorder was detected. It is tempting to speculate that these hemostatic abnormalities may contribute to the pathogenesis of moyamoya syndrome in some of our patients.

Prothrombotic abnormalities in children with venous thromboembolism.

PURPOSE: The aim of this study was to determine the frequency of acquired or inherited prothrombotic disorders in a pediatric population with venous thromboembolism (VTE). PATIENTS AND METHODS: From May 1992 to April 1998, 56 consecutive children with VTE were prospectively studied at a single center. RESULTS: The median age was 8.4 years (range, 0.1-18 years). There was a male predominance. Fifty (89%) children had thrombosis in the lower venous system. Risk factors were detected in 54 (96%) children. Twenty-one (38%) thrombotic episodes were related to central venous lines. Family history of thrombosis was positive in 13 (23%) patients. In 26 (46%) patients, a prothrombotic disorder was detected. Nine of them had inherited disorders (protein C deficiency, 5 patients; protein S deficiency, 3 patients; Factor V Leiden mutation, 1 patient), and 13 children had acquired disorders (antiphospholipid antibodies, 5 patients; antithrombin deficiency, 8 patients). The remaining four showed combined abnormalities (Factor V Leiden mutation associated with inherited protein S deficiency, 1 patient; acquired antithrombin deficiency, 2 patients and inherited antithrombin deficiency, 1 patient). CONCLUSIONS: In the series, a high percentage of prothrombotic disorders was detected; thus, a complete hemostatic evaluation should be performed in all of the children with VTE whether the patients have one or more risk factors.

Prethrombotic disorders in children with arterial ischemic stroke and sinovenous thrombosis.

BACKGROUND: Arterial ischemic stroke (AIS) and sinovenous thrombosis (SVT) are relatively rare events in children. The contribution of prethrombotic disorders to the etiology of these entities has not been completely elucidated. OBJECTIVES: To determine the frequency of inherited and acquired prethrombotic disorders in a pediatric population with AIS and SVT and to report clinical and radiological features. METHODS: From May 1992 to April 1997, 30 consecutive children with AIS and 10 children with SVT were assisted at a single institution. Hemostatic evaluation was performed for all the children. Evaluation included the following assays: protein C, protein S, antithrombin, plasminogen, activated protein C resistance, factor V Leiden mutation, and the detection of antiphospholipid antibodies. Data concerning baseline demographics, risk factors, presenting features, family history of thrombosis, and radiological findings were also recorded. RESULTS: One or more prethrombotic disorders were present in 9 children (30%) with AIS (inherited protein S deficiency, 2 patients; inherited protein C deficiency, 1 patient; acquired antithrombin deficiency, 2 patients; antiphospholipid antibodies, 3 patients; and antiphospholipid antibodies and plaminogen deficiency, 1 patient) and in 5 children (50%) with SVT (inherited protein S deficiency, 1 patient; acquired antithrombin deficiency, 3 patients; and antiphospholipid antibodies, 1 patient). CONCLUSIONS: Most children studied presented both a variety of risk factors for thrombosis and concomitant prethrombotic disorders. Therefore, a complete hemostatic evaluation for all children with AIS and SVT should be performed, despite the presence of obvious clinical risk factors or lack of family history of thrombosis.

Familial idiopathic myelofibrosis and multiple hemangiomas.

Idiopathic myelofibrosis (MF) is a rare disease in childhood. The clinical spectrum is very variable. Familial idiopathic MF has been recorded exceptionally. In previous reports idiopathic MF in childhood has been described in association with congenital anomalies and with chromosome abnormalities, although neither of these features have been reported in a familial context. We report two sisters with idiopathic MF and multiple eruptive hemangiomas. Details of their clinical signs, laboratory findings, and histologic features are described.

Molecular characterization of beta-thalassemia genes in an Argentine population.

This study was designed to identify the beta-thalassemia mutations in an Argentine population. Seventy-one pediatric patients and 101 available relatives were studied (85 chromosomes). Diagnosis of beta-thalassemia was made by conventional hematological procedures. Molecular studies were carried out by dot-blot and restriction endonuclease analysis on amplified DNA to detect the eight most frequent mutations in the Mediterranean area. We were able to identify 95.3% of the beta-thalassemia mutations in the subjects under study. The four common defects (C-39, 47%; IVS-I nt 110, 22.4%; IVS-I nt 1, 9.4%; and IVS-I nt 6, 5.9%) account for 84.7% of the beta-thalassemia alleles. The alleles and their distributions showed a close similarity to the spectrum of alleles in Italy. The differences might represent the influence of other immigrations, especially from Spain. We conclude that beta-thalassemia in Argentina originated mainly from Italian immigrants. This study will enable us to design an adequate approach to genetic counseling and/or prenatal diagnosis for couples at risk.