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Publications and source records attributed to A R Silva.
The authors provide a brief report on the historical evolution of visceral leishmaniasis in the State of Maranhão, Brazil, evaluating possible factors for growth of the disease in the State and control measures by the Brazilian Ministry of Health to integrate health services into the maintenance of control programs.
Glycerol is the cryoprotector most frequently used to freeze semen from different species. The objective of the present study was to compare the effect of single and fractionated glycerol addition on canine semen quality after thawing. Sperm fractions from 12 stud dogs were collected, evaluated, extended in Tris plus egg-yolk and separated into two aliquots to which glycerol was added in one step (single) or in three steps at 5-min intervals (fractionated). Semen was frozen and stored in liquid nitrogen and thawed after 1 week. A thermoresistance test was performed over a period of 120 min at 37-39 degrees C to evaluate the percentage of mobile spermatozoa (motility) and the status of motility (vigor) after thawing. There were no significant differences between the two methods of glycerol addition-immediately after thawing, and during the thermoresistance test-in sperm motility, vigor or morphology. A significant reduction in motility and vigor was found at 15 min after thawing and these parameters continued to decline until 120 min. In conclusion, glycerol can be added to canine semen in single or fractionated manner, but the single addition method is the easiest and the most practical to use.
The aim of this study was to assess the influence of biological markers of infection and antiretroviral therapy on the survival rate and quality of life in children with vertically-acquired HIV infection. This retrospective study was performed between August and October 2000. Outcome measures were presence of neurological disease, CD4 cell count, cranial computerized tomography (CT), electroencephalogram (EEG), use of antiretroviral agents, and mortality. The presence of neurological disease and of pathological findings in cranial computed tomography, and the lack of biological monitoring are associated with poor prognosis. Follow-up of this population should continue to allow long-term assessment of the social and biological impact of vertically-transmitted HIV.
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OBJECTIVE: The mechanisms involved in bone marrow eosinophil emigration and recruitment to inflammatory sites are not fully understood. The involvement of CD11b/CD18 in marrow eosinophil release induced by lipopolysaccharide (LPS) or allergen was investigated in mice. METHODS: Eosinophil and neutrophil counts in the pleural cavity, blood and bone marrow were performed at different time intervals after the intrathoracic injection of LPS (250 ng/cavity) or ovalbumin (OVA, 12 microg/cavity; into actively sensitized mice) and compared to anti-CD11b/CD 18 (5C6, 1 mg/mouse) or anti-IL-5 (TRFK-5, 500 microg/kg) treated mice. RESULTS: LPS induced local eosinophil influx, that peaked within 24 h and that was preceded by a decrease in marrow eosinophils at 4 h. Antigenic challenge induced a decrease in marrow eosinophils within 4 h, followed by a long lasting pleural eosinophil accumulation and a persistent increase in marrow eosinophil numbers. Pretreatment with anti-CD11b/CD18 abolished LPS-induced neutrophil and eosinophil accumulation in the pleural cavity at 4 and 24 h, respectively. This pretreatment failed to modify neutrophil emigration from bone marrow, but significantly inhibited marrow eosinophil release at 4 h post-LPS or OVA challenge. Anti-IL-5 pretreatment failed to inhibit LPS-induced pleural eosinophil accumulation and mobilization from bone marrow, but it abolished allergen-induced effects, indicating a role for IL-5 in marrow eosinophil mobilization induced by antigen, but not by LPS challenge. CONCLUSIONS: Our results suggest that eosinophil migration induced by antigen or LPS into the pleural cavity is preceded by bone marrow eosinophil release through a mechanism that depends on CD11b/CD18.
In the present study we investigated the effects of L-pyroglutamic acid (PGA), which predominantly accumulates in the inherited metabolic diseases glutathione synthetase deficiency (GSD) and gamma-glutamylcysteine synthetase deficiency (GCSD), on some in vitro parameters of energy metabolism and lipid biosynthesis. We evaluated the rates of CO2 production and lipid synthesis from [U-14C]acetate, as well as ATP levels and the activities of creatine kinase and of the respiratory chain complexes I-IV in cerebral cortex of young rats in the presence of PGA at final concentrations ranging from 0.5 to 3 mM. PGA significantly reduced brain CO2 production by 50% at the concentrations of 0.5 to 3 mM, lipid biosynthesis by 20% at concentrations of 0.5 to 3 mM and ATP levels by 52% at the concentration of 3 mM. Regarding the enzyme activities, PGA significantly decreased NADH:cytochrome c oxireductase (complex I plus CoQ plus complex III) by 40% at concentrations of 0.5-3.0 mM and cytochrome c oxidase activity by 22-30% at the concentration of 3.0 mM, without affecting the activities of succinate dehydrogenase, succinate:DCPIP oxireductase (complex II), succinate:cytochrome c oxireductase (complex II plus CoQ plus complex III) or creatine kinase. The results strongly indicate that PGA impairs brain energy production. If these effects also occur in humans, it is possible that they may contribute to the neuropathology of patients affected by these diseases.
2-Hydroxybutyric acid appears at high concentrations in situations related to deficient energy metabolism (e.g., birth asphyxia) and also in inherited metabolic diseases affecting the central nervous system during neonatal development, such as "cerebral" lactic acidosis, glutaric aciduria type II, dihydrolipoyl dehydrogenase (E3) deficiency, and propionic acidemia. The present study was carried out to determine the effect of 2-hydroxybutyric acid at various concentrations (1-10 mM) on CO2 production and lipid synthesis from labeled substrates in cerebral cortex of 30-day-old Wistar rats in vitro. CO2 production was significantly inhibited (30-70%) by 2-hydroxybutyric acid in cerebral cortex prisms, in total homogenates and in the mitochondrial fraction. We also demonstrated a significant inhibition of lipid synthesis (20-45%) in cerebral cortex prisms and total homogenates in the presence of 2-hydroxybutyric acid. However, no inhibition of lipid synthesis occurred in homogenates free of nuclei and mitochondria. The results indicate an impairment of mitochondrial energy metabolism caused by 2-hydroxybutyric acid, a fact that may secondarily lead to reduction of lipid synthesis. It is possible that these findings may be associated with the neuropathophysiology of the situations where 2-hydroxybutyric acid is accumulated.
Lysophosphatidylcholine is an abundant component of plasma and oxidized LDL that displays several biological activities, some of which may occur through the platelet-activating factor (PAF) receptor. We find that commercial lysophosphatidylcholine, its alkyl homolog (lyso-PAF), and PAF all induce inflammation in a murine model of pleurisy. Hydrolysis of PAF to lyso-PAF by recombinant PAF acetylhydrolase abolished this eosinophilic infiltration, implying that lyso-PAF should not have displayed inflammatory activity. Saponification of lyso-PAF or PAF acetylhydrolase treatment of lyso-PAF or lysophosphatidylcholine abolished activity; neither lysolipid should contain susceptible sn-2 residues, suggesting contaminants account for the bioactivity. Lyso-PAF and to a lesser extent lysophosphatidylcholine stimulated Ca(2+) accumulation in 293 cells stably transfected with the human PAF receptor, and this was inhibited by specific PAF receptor antagonists. Again, treatment of lyso-PAF or lysophosphatidylcholine with recombinant PAF acetylhydrolase, a nonselective phospholipase A(2), or saponification of lyso-PAF destroyed the PAF-like activity, a result incompatible with lyso-PAF or lysophosphatidylcholine being the actual agonist. We conclude that neither lyso-PAF nor lysophosphatidylcholine is a PAF receptor agonist, nor are they inflammatory by themselves. We suggest that PAF or a PAF-like mimetic accounts for inflammatory effects of lysophosphatidylcholine and lyso-PAF.
The present study investigated the effects of glutaric acid (GA), which predominantly accumulates in glutaric acidemia type I (GA-I), on some in vitro parameters of energy metabolism in cerebral cortex of rats. We first evaluated CO2 production from [U-14C] acetate, as well as ATP levels in brain of young Wistar rats. The effect of the acid on the activities of the respiratory chain complexes were also investigated. GA was tested at final concentrations ranging from 0.5 to 5.0 mM. GA significantly reduced brain CO2 production by 50% at the concentrations of 0.5 to 3.0 mM, ATP levels by 25% at the concentration of 3.0 mM, succinate:cytochrome C oxireductase (complex II plus CoQ plus complex III) by 25% at 5 mM concentration, and NADH:cytochrome C oxireductase (complex I plus CoQ plus complex Ill) by 25% at 2.5 and 5 mM concentrations. The results strongly indicate that GA impairs brain energy production. If these effects also occur in humans, it is possible that they may contribute to the neuropathology of patients affected by GA-I.
Oxidation of human low density lipoprotein (LDL) generates proinflammatory mediators and underlies early events in atherogenesis. We identified mediators in oxidized LDL that induced an inflammatory reaction in vivo, and activated polymorphonuclear leukocytes and cells ectopically expressing human platelet-activating factor (PAF) receptors. Oxidation of a synthetic phosphatidylcholine showed that an sn-1 ether bond confers an 800-fold increase in potency. This suggests that rare ether-linked phospholipids in LDL are the likely source of PAF-like activity in oxidized LDL. Accordingly, treatment of oxidized LDL with phospholipase A(1) greatly reduced phospholipid mass, but did not decrease its PAF-like activity. Tandem mass spectrometry identified traces of PAF, and more abundant levels of 1-O-hexadecyl-2-(butanoyl or butenoyl)-sn-glycero-3-phosphocholines (C(4)-PAF analogs) in oxidized LDL that comigrated with PAF-like activity. Synthesis showed that either C(4)-PAF was just 10-fold less potent than PAF as a PAF receptor ligand and agonist. Quantitation by gas chromatography-mass spectrometry of pentafluorobenzoyl derivatives shows the C(4)-PAF analogs were 100-fold more abundant in oxidized LDL than PAF. Oxidation of synthetic alkyl arachidonoyl phosphatidylcholine generated these C(4)-PAFs in abundance. These results show that quite minor constituents of the LDL phosphatidylcholine pool are the exclusive precursors for PAF-like bioactivity in oxidized LDL.
4-Hydroxybutyric acid (4HB) is accumulated in succinic semialdehyde dehydrogenase deficiency, an inherited metabolic disease severely affecting the CNS during postnatal development. Thus, the present study was designed to evaluate the in vitro influence of 4HB on lipid synthesis and CO2 production from [U-14C] acetate in cerebral cortex of 30-day-old Wistar rats. In the presence of 4HB, there was an inhibition of lipid synthesis in cerebral cortex prisms and homogenates. However, no inhibition of lipid synthesis occurred in the homogenates free of nuclei and mitochondria. In addition, CO2 production was inhibited by 4HB in cerebral cortex prisms, and homogenates and in the mitochondrial fraction. These results might possibly be explained by an impairment of mitochondrial metabolism by 4HB which may secondarily inhibit lipid synthesis. The results reported here may help to better understand the neuropathophysiology of 4-hydroxybutyric aciduria.
1. The role of both exogenously administered and endogenously generated bradykinin (BK) on LPS-induced eosinophil accumulation in the mice pleural cavity was investigated by means of treatment with BK selective receptor agonists/antagonists and captopril. 2. Intrathoracic (i.t.) injection of LPS (250 ng cavity(-1)) induced eosinophil influx at 24 h as previously described (Bozza et al., 1993). Pretreatment with the B1 receptor antagonist des-Arg9-[leu-8]BK (0.025 and 0.25 nmol cavity(-1)) showed no effect on this phenomenon, whereas pretreatment with the B2 receptor antagonists, NPC 17731 (0.025 and 0.25 nmol cavity(-1)) or HOE 140 (2.5 nmol cavity(-1)), increased LPS-induced eosinophil influx. Accordingly, pretreatment with captopril at 10 mg kg(-1) i.p., inhibited eosinophil infiltration induced by LPS in the pleural cavity, suggesting that endogenous BK is down-regulating LPS-induced eosinophil accumulation. 3. BK administered at 15 and 25 nmol cavity(-1), i.t. or i.p. also inhibited LPS-induced eosinophil accumulation. BK alone had no effect on the basal number of leucocytes in the pleural or peritoneal cavity in doses up to 25 nmol cavity(-1). Nevertheless, when injected at doses of 50 and 100 nmol cavity(-1) BK induced leucocyte influx characterized by neutrophil and eosinophil accumulation at 24 h. 4. Similarly to what was observed with BK, a specific B2 receptor agonist, Tyr8BK, administered at 0.25 nmol cavity(-1) i.p., significantly inhibited the eosinophil influx induced by LPS. 5. The mechanism by which B2 receptor agonists inhibit LPS-induced eosinophil accumulation was investigated by pretreating the animals with indomethacin or a selective cyclooxygenase-2 inhibitor, NS-398. Pretreatment with either indomethacin or NS-398 had no effect on eosinophil influx induced by LPS alone, but those drugs were able to restore the LPS-induced eosinophil influx in Tyr8BK (0.25 nmol cavity(-1)) injected mice. 6. In conclusion, endogenously generated bradykinin seems to modulate, through activation of B2 receptors, eosinphil accumulation induced by LPS via a mechanism dependent on prostanoid synthesis.
A role for catecholamines in the regulation of the blood neutrophilia induced by intravenous (i.v.) injection of lipopolysaccharide (LPS; 250 micrograms/kg) was examined in Wistar rats by means of surgical adrenalectomy or pretreatment with adrenergic and dopaminergic antagonists into naive animals. Treatment of animals with a single dose (250 micrograms/kg) of LPS caused a dramatic increase in the number of circulating neutrophils concomitant with a decrease in the number of these cells in the bone marrow. These effects were partially reversed when catecholamine stores were depleted with reserpine. It was found that neither adrenalectomy nor pretreatment with the dopaminergic antagonists, chlorpromazine and pimozide, affected the changes in neutrophil counts induced by LPS. The injection of the alpha 1/alpha 2-adrenoceptor antagonist, phentolamine, and the selective alpha 1-adrenoceptor antagonist, prazosin, significantly decreased blood neutrophilia induced by LPS. However, neither the selective alpha 2-adrenoceptor antagonist, yohimbine, nor the beta-adrenoceptor antagonist, propranolol, had any effect on LPS response. Taken together, these findings support the hypothesis that the catecholamine norepinephrine plays a role in the regulation of the LPS-induced neutrophilia through activation of alpha 1-adrenoceptors.
In the present work we review the existing evidence for a LPS-induced cytokine-mediated eosinophil accumulation in a model of acute inflammation. Intrathoracic administration of LPS into rodents (mice, rats or guinea pigs) induces a significant increase in the number of eosinophils recovered from the pleural fluid 24 hr later. This phenomenon is preceded by a neutrophil influx and accompanied by lymphocyte and monocyte accumulation. The eosinophil accumulation induced by LPs is not affected by inhibitors of cyclo or lipoxygenase nor by PAF antagonists but can be blocked by dexamethasone or the protein synthesis inhibitor cycloheximide. Transfer of cell-free pleural wash from LPS injected rats (LPS-PW) to naive recipient animals induces a selective eosinophil accumulation within 24 hr. The eosinophilotactic activity present on the LPS-PW has a molecular weight ranging between 10 and 50 kDa and its effect is abolished by trypsin digestion of the pleural wash indicating the proteic nature of this activity. The production of the eosinophilotactic activity depends on the interaction between macrophages and T-lymphocytes and its effect can not be blocked by anti-IL-5 monoclonal antibodies. Accumulated evidence suggest that the eosinophil accumulation induced by LPS is a consequence of a eosinophilotactic cytokine produced through macrophage and T-cell interactions in the site of a LPS-induced inflammatory reaction.
The involvement of platelet-activating factor (PAF) in lipopolysaccharide (LPS)-induced leukocyte accumulation in the rat pleural cavity was investigated. Intrathoracic (i.t.) injection of LPS (250 ng/cavity) induced a marked increase in the number of neutrophils at 1 h, which was maximum within 6-12 h, reducing after 24 h. In parallel, an increase in blood neutrophil counts within 1-6 h, concomitantly with a reduction in the number of these cells in the bone marrow, was observed. The number of eosinophils recovered from LPS-injected pleural cavity increased at 12 h and was maximum within 24-48 h. No change in blood or bone marrow eosinophil counts was detected. The pretreatment with WEB 2086 or PCA 4248 (20 mg/kg) significantly inhibited pleural neutrophil accumulation, blood neutrophilia and the decrease in the marrow neutrophil content, but not eosinophil accumulation. The blood neutrophilia and the decrease in marrow neutrophil counts induced by the intravenous (i.v.) injection of LPS (250 ng) were significantly lower than those observed after i.t. injection. Furthermore, WEB 2086 and PCA 4248 were ineffective against the systemic alteration induced by i.v. LPS. it was concluded that LPS-induced neutrophil, but not eosinophil, accumulation in the pleural cavity is related to the mobilization of neutrophils from the bone marrow and involves PAF dependent mechanisms.
This work has evaluated the clastogenicity of six extracts (tea and aqueous extract of leaves, tea, aqueous and methanolic extracts of dried fruit, and tea of unripe fruit) obtained from Crotalaria retusa L. and three extracts (tea and methanolic extract of dried fruit, and tea of unripe fruit) obtained from Crotalaria mucronata Desv. The extracts were injected intraperitoneally into mice, and the animals were killed 24 h after treatment for preparation of bone marrow cells. The extracts obtained from fruits of Crotalaria retusa were found to cause a dose-dependent increase in the frequency of chromosomal aberrations in mice. On the other hand, no statistically significant increase in the frequency of aberrant cells was observed for the animals treated with leaf extracts obtained from Crotalaria retusa and with extracts from fruits of Crotalaria mucronata. The possibility that the pyrrolizidine alkaloid, monocrotaline, present in Crotalaria retusa exerts a clastogenic effect on mouse bone marrow cells is discussed. Our conclusion is based on studies using intraperitoneal treatments. Effects of oral exposure to extracts of Crotalaria retusa are unknown.
The inhibition of the haematological alterations and prevention of death due to systemic anaphylaxis after antigen challenge were investigated in rats after various drug treatments. The i.v. injection of ovalbumin (250 micrograms/kg) into actively sensitized rats induced marked thrombocytopenia and haemoconcentration within 5 min and significant leukocytosis within 30 min, lasting for 2 h after the challenge. Pretreatment with meclizine or terfenadine (15-30 mg/kg i.p.) inhibited antigen-induced haemoconcentration, whereas WEB 2086 (2-10 mg/kg i.p.) and PCA 4248 (5-10 mg/kg p.o.), two platelet-activating factor (PAF) antagonists, interfered with thrombocytopenia only. Azelastine (1-20 mg/kg p.o.) dose dependently inhibited antigen-induced haemoconcentration and thrombocytopenia but failed to block leukocytosis. Azelastine also inhibited the thrombocytopenia observed after the i.v. administration of PAF (4 micrograms/kg). Administration of ovalbumin at a dose of 1.5 mg/kg resulted in a lethal anaphylactic reaction in about 85% of the rats. Pretreatment with WEB 2086 (10 mg/kg i.p.), meclizine (30 mg/kg i.p.) or both increased the survival rate from 15 to 57, 68 and 87%, respectively. Azelastine alone (20 mg/kg p.o.) completely blocked the lethal reaction. It was concluded that the ability of azelastine to antagonize histamine and PAF is important for its effectiveness against anaphylactic shock.
Toxicological and toxicogenetic effects of aqueous (tea) and hexanic fruit extract of Indigofera suffruticosa Mill. and hydroalcoholic root extract of Solanum agrarium Stendt. were evaluated in Balb C male mice intraperitoneally exposed. A hepatotoxic effect was observed just for animals treated with aqueous fruit extract of I. suffruticosa. In relation to the toxicogenetic effect, just the group treated with 12.5% of toxic dose of aqueous fruit extract of I. suffruticosa showed a statistically significant increase in the frequency of cells with chromosome aberrations (cytogenetic effect), although a slight increase was also observed for the highest dose (25% of LD50) of hydroalcoholic root extract of S. agrarium. The results obtained show that before S. agrarium is used as medicine and before the wide use of I. suffruticosa in cattle food, careful evaluation must be done.