Cardiovascular actions of rattlesnake bradykinin ([Val(1), Thr(6)] bradykinin) in the anesthetized South American rattlesnake Crotalus durissus terrificus

Incubation of heat-denatured plasma from the rattlesnake Crotalus atrox with trypsin generated a bradykinin (BK) that contained two amino acid substitutions (Arg(1) --> Val and Ser(6) --> Thr) compared with mammalian BK. Bolus intra-arterial injections of synthetic rattlesnake BK (0.01-10 nmol/kg) into the anesthetized rattlesnake, Crotalus durissus terrificus, produced a pronounced and concentration-dependent increase in systemic vascular conductance (Gsys). This caused a fall in systemic arterial blood pressure (Psys) and an increase in blood flow. Heart rate and stroke volume also increased. This primary response was followed by a significant rise in Psys and pronounced tachycardia (secondary response). Pretreatment with N-G-nitro-L-arginine methyl ester reduced the NK-induced systemic vasodilatation, indicating that the effect is mediated through increased NO synthesis. The tachycardia associated with the late primary and secondary response to BK was abolished with propranolol and the systemic vasodilatation produced in the primary phase was also significantly attenuated by pretreatment, indicating that the responses are caused, at least in part, by release of cathecholamines and subsequent stimulation of beta-adrenergic receptors. In contrast, the pulmonary circulation was relatively unresponsive to BK.

Causas de variação nos preços de bovinos nelore elite no Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Molecular characterization of bacterial populations of different soils

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Stochastic stability for Markovian jump linear systems associated with a finite number of jump times

This paper deals with a stochastic stability concept for discrete-time Markovian jump linear systems. The random jump parameter is associated to changes between the system operation modes due to failures or repairs, which can be well described by an underlying finite-state Markov chain. In the model studied, a fixed number of failures or repairs is allowed, after which, the system is brought to a halt for maintenance or for replacement. The usual concepts of stochastic stability are related to pure infinite horizon problems, and are not appropriate in this scenario. A new stability concept is introduced, named stochastic tau-stability that is tailored to the present setting. Necessary and sufficient conditions to ensure the stochastic tau-stability are provided, and the almost sure stability concept associated with this class of processes is also addressed. The paper also develops equivalences among second order concepts that parallels the results for infinite horizon problems. (C) 2003 Elsevier B.V. All rights reserved.

EBNA-1 gene sequences in Brazilian and American patients with Hodgkin's disease

We examined the types of Epstein-Barr virus-associated nuclear antigen-1 (EBNA-1) gene carboxy (C)-terminal mutations occurring in Hodgkin's disease (HD) and reactive tissues from two different geographic regions. Previously reported EBNA-1 C-terminal region amino acid sequence variants, based on the amino acid at codon 487, include Prototype (P)-ala, which is found in the B95.8-derived prototype virus, P-thr, Variant (V)-leu, V-val, and V-pro. Using polymerase chain reaction (PCR) to amplify portions of the EBNA-1 gene, followed by DNA sequencing, we found a single EBNA-1 gene sequence variant in each tissue, whether reactive or neoplastic and whether from Brazil or the United States. Variant EBNA-1 gene sequences were more common in both neoplastic and non-neoplastic tissues from different geographic areas than the so-called prototype sequence. In the 17 Brazilian HD cases, 4 cases had P-thr variants and 13 had V-leu variants. In the six reactive tissues from Brazil, one had a P-ala variant, two had P-thr variants, and three had V-leu variants. In the 12 American HD cases, 2 had P-ala variants, 6 had P-thr variants, and 4 had V-leu variants. The 11 American reactive tissues included 2 P ala variants, 5 P-thr variants, and 4 V-leu variants. In both countries, there were similar variant EBNA-1 sequences present in normal tissues and HD cases. Compared with the P ala and P-thr cases, the V-leu cases were more likely to have the 30-bp latent membrane protein 1 (LMP1) gene deletion (P = 0.0075). In addition, cases of HD with the V-leu were statistically associated with a substitution of asparagine for glutamine at codon 322 of the C-terminal portion of the LMP1 gene. Our results suggest that any variation in EBNA-1 gene sequence is caused by a polymorphism present in pre-existing viral strains in the underlying population, and not a mutation occurring during oncogenesis. (C) 1999 by the American Society of Hematology.

Interaction between arginine vasopressin and angiotensin II receptors in the central regulation of sodium balance

We speculated that the influence of lateral preoptic area (LPO) in sodium balance, involves arginine(8)-vasopressin (AVP) and angiotensin (ANG II) on Na+ uptake in LPO. Therefore, the present study investigated the effects of central administration of specific AVP and ANG 11 antagonists (d(CH2)(5)-Tyr (Me)-AVP (AAVP) and [Adamanteanacetyl(1), 0-ET-D-Tyr(2), Val(4), Aminobutyryl(6), Arg(8.9)]-AVP (ATAVP) antagonists of V-1 and V-2 receptors of AVP. Also the effects of losartan and CGP42112A (selective ligands of the AT(1) and AT(2) angiotensin receptors, respectively), was investigated on Na+ uptake and renal fluid and electrolyte excretion. After an acclimatization period of 7 days, the animals were maintained under tribromoethanol (200 mg/kg body weight, intraperitonial) anesthesia and placed in a Kopf stereotaxic instrument. Stainless guide cannula was implanted into the LPO. AAVP and ATAVP injected into the LPO prior to AVP produced a reduction in the NaCl intake. Both the AT(1) and AT(2) ligands administered into the LPO elicited a decrease in the NaCl intake induced by AVP injected into the LPO. AVP injection into the LPO increased sodium renal excretion, but this was reduced by prior AAVP administration. The ATAVP produced a decreased in the natriuretic effect of AVP. The losartan injected into LPO previous to AVP decreased the sodium excretion and the CGP 421122A also decreased the natriuretic effect of AVP. The AVP produced an antidiuresis effect that was inhibited by prior administration into LPO of the ATAVP. The AAVP produced no change in the antidiuretic effect of AVP. These results suggest that LPO are implicated in sodium balance that is mediated by V-1, V-2, AT(2) and AT(2) receptors. (c) 2005 Elsevier B.V All rights reserved.

Influence of arginine vasopressin receptors and angiotensin receptor subtypes on the water intake and arterial blood pressure induced by vasopressin injected into the lateral septal area of the rat

In this study we investigated the influence of d(CH2)(5)-Tyr(Me)-[Arg(8)]vasopressin (AAVP) and [adamanteanacetyl(1),0-ET-DTyr(2), Val(4), aminobutyryl(6), Arg(8,9)]-[Arg(8)]vasopressin (ATAVP), which are antagonists of vasopressin V-1 and V-2 receptors, and the effects of losartan, a selective angiotensin AT(1) receptor antagonist, and CGP42112A, a selective AT(2) receptor antagonist, injected into the lateral septal area (LSA) on thirst and hypertension induced by [Arg(8)]vasopressin (AVP). AAVP and ATAVP injected into the LSA reduced the drinking responses elicited by injecting AVP into the LSA. Both the AT(1) and AT(2) ligands administered into the LSA elicited a concentration-dependent decrease in the water intake induced by AVP injected into the LSA, but losartan was more effective than CGP42112A. The increase in MAP, due to injection of AVP into the LSA, was reduced by prior injection of AAVP from 18 +/- 1 to 6 +/- 1 mm Hg. Losartan injected into the LSA prior to AVP reduced the increase in MAP to 7 +/- 0.8 mm Hg. ATAVP and CGP42112A produced no changes in the pressor effect of AVP. These results suggest that the dipsogenic effects induced by injecting AVP into the LSA were mediated primarily by AT(1) receptors. However, doses of losartan were more effective when combined with CGP42112A than when given alone, suggesting that the thirst induced by AVP injections into LSA may involve activation of multiple AVP and angiotensin II receptor subtypes. The pressor response of AVP was reduced by losartan and by AAVP. CGP42112A and ATAVP did not change the AVP pressor response. These results suggest that facilitator effects of AVP on water intake are mediated through the activation of V-1 receptors and that the inhibitory effect requires V-2 receptors. The involvement of AT(1) and AT(2) receptors can be postulated. Based on the present findings, we suggest that the AVP in the LSA may play a role in the control of water and arterial blood pressure balance. (C) 2004 Elsevier B.V. All rights reserved.

Laurdan Spectrum Decomposition as a Tool for the Analysis of Surface Bilayer Structure and Polarity: a Study with DMPG, Peptides and Cholesterol

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

ZapA, a possible virulence factor from Proteus mirabilis exhibits broad protease substrate specificity

The opportunistic bacterium Proteus mirabilis secretes a metalloprotease, ZapA, considered to be one of its virulence factors due to its IgA-degrading activity. However, the substrate specificity of this enzyme has not yet been fully characterized. In the present study we used fluorescent peptides derived from bioactive peptides and the oxidized ß-chain of insulin to determine the enzyme specificity. The bradykinin- and dynorphin-derived peptides were cleaved at the single bonds Phe-Ser and Phe-Leu, with catalytic efficiencies of 291 and 13 mM/s, respectively. Besides confirming already published cleavage sites, a novel cleavage site was determined for the ß-chain of insulin (Val-Asn). Both the natural and the recombinant enzyme displayed the same broad specificity, demonstrated by the presence of hydrophobic, hydrophilic, charged and uncharged amino acid residues at the scissile bonds. Native IgA, however, was resistant to hydrolysis by ZapA.

Phylogenetic relationships within anuran clade Terrarana, with emphasis on the placement of Brazilian Atlantic rainforest frogs genus Ischnocnema (Anura: Brachycephalidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Richards growth model and viability indicators for populations subject to interventions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bioactive Metabolites Produced by Penicillium sp.1 and sp.2, Two Endophytes Associated with Alibertia macrophylla (Rubiaceae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bacterial diversity of soil under eucalyptus assessed by 16S rDNA sequencing analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Indicadores de desempenho em rebanho da raça Holandesa: curvas de crescimento e altura, características reprodutivas, produtivas e parâmetros genéticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alternativas para seleção de touros da raça Nelore considerando características múltiplas de importância econômica

Os dados são provenientes de 234 touros da raça Nelore participantes de um teste de progênie, no período de 1996 a 2003. A diferença esperada na progênie (DEP) de sete características: peso aos 120 e 210 dias, efeito materno (DMPP120 e DMPP210), peso e perímetro escrotal aos 365 e 450 dias, efeito direto (DDP365, DDP450, DDPE365 e DDPE450) e idade ao primeiro parto (DDIPP) foi utilizada para classificar os animais em três grupos, assim como identificar quais as características possuíram maior poder discriminatório na formação de cada grupo. Para tanto, foram utilizados procedimentos estatísticos multivariados de análise de agrupamentos k-médias e componentes principais. Os resultados evidenciaram que, dos três grupos formados, dois se destacaram quanto aos valores médios das DEPs. A importância desses dois grupos de touros foi confirmada pela análise de componentes principais, que associou a eles valores superiores de DEPs diretas de peso e perímetro escrotal. A quantidade da variabilidade original retida pelos dois primeiros componentes principais foi de 70,22%. Estes procedimentos mostraram-se eficientes e constituíram importantes ferramentas para classificar touros, discriminar variáveis, bem como resumir informações multivariadas, podendo ser usados como auxílio valioso na seleção de reprodutores para uso nos programas de melhoramento genético.