Rol del sistema kallicreína kinina y su interrelación con sistemas vasoactivos durante la preñez / Role of the kallikrein kinin system and its interrelationship with vasoactive systems in pregnancy

La hiperfiltración glomerular y el aumento de la reabsorción de sodio son factores fundamentales para el desarrollo de la unidad feto placentaria. Dichos factores resultan de adaptaciones hemodinámicas y renales en las que participan sistemas vasoactivos. Se pudo demostrar en ratas que la activación del sistema kallicreína kinina (SKK) precede a la instalación de la hiperfiltración glomerular, dado que su inhibición por aprotinina previene el aumento del filtrado glomerular. Además, la inhibición individual o asociada de los efectores específicos del SKK, las prostaglandinas (PGs) y el óxido nítrico (ON), confirman la dependencia del filtrado glomerular del SKK durante la preñez. Encontramos también que el sistema renina angiotensina (SRA) participa en la generación de la hiperfiltración glomerular dado que ésta es afectada por la administración de bloqueantes del SRA. La inhibición máxima sobre el pico de hiperfiltración se obtuvo con el bloqueo de ambos sistemas (SKK y SRA). Además, estrategias para alterar la hiperfiltración glomerular y la reabsorción de sodio de la preñez evidenciaron alteraciones en el desarrollo de la unidad feto placentaria, menor número de crías, mayor cantidad de reabsorciones intrauterinas y retardo en el crecimiento. El tratamiento combinado de inhibidores del SKK asociados a bloqueantes del SRA o de óxido nítrico mostraron los mayores efectos. En consecuencia, demostramos que el SKK juega un rol central en los fenómenos de adaptación que acompañan la preñez normal. La interrelación del SKK con varios sistemas vasoactivos parecería formar una red que participa en las adaptaciones hemodinámicas para un adecuado desarrollo de la gestación y de la unidad feto-placentaria.

Glomerular hyperfiltration and increased sodium reabsorption are key factors for the development of the fetus and placenta in pregnancy. These adjustments result from hemodynamic and renal factors involving vasoactive systems. It was demonstrated in rats that activation of KKS precedes the installation of glomerular hyperfiltration as aprotinin prevents the increase in glomerular filtration. In addition, individual or associated inhibition of specific kallikrein kinin system effectors, prostaglandins (PGs) and nitric oxide (NO), confirm the glomerular filtration rate dependence of KKS during pregnancy. It was also found that the renin-angiotensin system (RAS) contributes to glomerular hyperfiltration as this is affected by the administration of RAS blockers. The peak of hyperfiltration maximum inhibition was obtained by the blockade of both systems (KKS and RAS). In addition, strategies used to alter the glomerular hyperfiltration and increased sodium reabsorption during pregnancy, showed abnormalities in the development of the fetus and placenta, fewer offspring, more fetus resorptions and intrauterine growth retardation. KKS inhibitors associated with RAS or nitric oxide blockers showed the greatest impact. As a consequence, it was demonstrated that KKS plays a central role in the adaptation phenomenom that accompanies normal pregnancy. The interplay of KKS with several vasoactive systems, seem to arrange a network involved in the hemodynamic adaptations to allow the proper development of pregnancy and the fetus and placenta.

Avaliação da aprotinina na redução da resposta inflamatória sistêmica em crianças operadas com circulação extracorpórea / Assessment of aprotinin in the reduction of inflammatory systemic response in children undergoing surgery with cardiopulmonary bypass

OBJETIVO: Avaliar se a aprotinina em altas doses hemostáticas pode reduzir o processo inflamatório após circulação extracorpórea (CEC) em crianças. MÉTODOS: Estudo prospectivo randomizado em crianças de 30 dias a 4 anos de idade, submetidas à correção de cardiopatia congênita acianogênica, com CEC e divididas em dois grupos, um denominado Controle (n=9) e o outro, Aprotinina (n=10). Neste, o fármaco foi administrado antes e durante a CEC. A resposta inflamatória sistêmica e disfunções hemostática e multiorgânicas foram analisadas por marcadores clínicos e bioquímicos. Foram consideradas significantes as diferenças com P<0,05. RESULTADOS: Os grupos foram semelhantes quanto às variáveis demográficas e intra-operatórias, exceto por maior hemodiluição no Grupo Aprotinina. Não houve benefício quanto aos tempos de ventilação pulmonar mecânica, permanência no CTIP e hospitalar, nem quanto ao uso de inotrópicos e função renal. A relação PaO2/FiO2 (pressão parcial de oxigênio arterial/fração inspirada de oxigênio) apresentou queda significativa com 24 h pós-operatório, no Grupo Controle. As perdas sanguíneas foram semelhantes nos dois grupos. No grupo Aprotinina surgiu leucopenia significativa, em CEC, seguida de leucocitose. Fator de necrose tumoral alfa (TNF-α), Interleucinas (IL)-6, IL-8, IL-10, proporção IL-6/IL-10 não apresentaram diferenças marcantes intergrupos. A proporção IL-6/IL-10 PO aumentou no grupo Controle. Não houve complicações com o uso da aprotinina. CONCLUSÃO: Nesta casuística, a Aprotinina em altas doses hemostáticas não minimizou as manifestações clínicas e os marcadores séricos de resposta inflamatória sistêmica.

OBJECTIVE: To evaluate if the hemostatic high-dose aprotinin seems to reduce the inflammatory process after extracorporeal circulation (ECC) in children. METHODS: A prospective randomized study was conducted on children aged 30 days to 4 years submitted to correction of acyanogenic congenital heart disease with ECC and divided into two groups: Control (n=9) and Aprotinin (n=10). In the Aprotinin Group the drug was administered before and during ECC and the systemic inflammatory response and hemostatic and multiorgan dysfunctions were analyzed on the basis of clinical and biochemical markers. Differences were considered to be significant when P<0.05. RESULTS: The groups were similar regarding demographic and intraoperative variables, except for a greater hemodilution in the Aprotinin Group. The drug had no benefit regarding time of mechanical pulmonary ventilation, permanence in the postoperative ICU and length of CONCLUSION: In this series, hemostatic high-dose aprotinin did not minimize the clinical manifestations or serum markers of the inflammatory systemic response.

Purification of elastase-like chymotrypsin from cardamom shoot and Capsule borer [corrected]

An elastase-like chymotrypsin was purified by aprotinin-agarose affinity chromatography from the midgut extract of cardamom shoot and capsule borer, Conogethes punctiferalis. The purified enzyme had a Vmax of 687.6 +/- 22.1 nmole pNA released/min/mg protein, Km of 0.168 +/- 0.012 mM with SAAPLpNA as substrate and gave a single band on SDS-PAGE with a molecular mass of 72.1 kDa. Casein zymogram revealed one clear zone of proteolytic activity, which corresponded to the band obtained with SDS-PAGE indicating that this could be a single-polypeptide enzyme.

Subcellular localization of an intracellular serine protease of 68 kDa in Leishmania (Leishmania) amazonensis promastigotes

Here we report the subcellular localization of an intracellular serine protease of 68 kDa in axenic promastigotes of Leishmania (Leishmania) amazonensis, using subcellular fractionation, enzymatic assays, immunoblotting, and immunocytochemistry. All fractions were evaluated by transmission electron microscopy and the serine protease activity was measured during the cell fractionation procedure using a-N-r-tosyl-L-arginine methyl ester (L-TAME) as substrate, phenylmethylsulphone fluoride (PMSF) and L-1-tosylamino-2-phenylethylchloromethylketone (TPCK) as specific inhibitors. The enzymatic activity was detected mainly in a membranous vesicular fraction (6.5-fold enrichment relative to the whole homogenate), but also in a crude plasma membrane fraction (2.0-fold). Analysis by SDS-PAGE gelatin under reducing conditions demonstrated that the major proteolytic activity was found in a 68 kDa protein in all fractions studied. A protein with identical molecular weight was also recognized in immunoblots by a polyclonal antibody against serine protease (anti-SP), with higher immunoreactivity in the vesicular fraction. Electron microscopic immunolocalization using the same polyclonal antibody showed the enzyme present at the cell surface, as well as in cytoplasmic membranous compartments of the parasite. Our findings indicate that the internal location of this serine protease in L. amazonensis is mainly restricted to the membranes of intracellular compartments resembling endocytic/exocytic elements.

Inhibition of tryptase release from human colon mast cells by histamine receptor antagonists.

The main objective of this study was to investigate the ability of histamine receptor antagonists to modulate tryptase release from human colon mast cells induced by histamine. Enzymatically dispersed cells from human colon were challenged with histamine in the absence or presence of the histamine receptor antagonists, and the tryptase release was determined. It was found that histamine induced tryptase release from colon mast cells was inhibited by up to approximately 61.5% and 24% by the H1 histamine receptor antagonist terfenadine and the H2 histamine receptor antagonist cimetidine, respectively, when histamine and its antagonists were added to cells at the same time. The H3 histamine receptor antagonist clobenpropit had no effect on histamine induced tryptase release from colon mast cells at all concentrations tested. Preincubation of terfenadine, cimetidine or clobenpropit with cells for 20 minutes before challenging with histamine did not enhance the ability of these antihistamines to inhibit histamine induced tryptase release. Apart from terfenadine at 100 microg/ml, the antagonists themselves did not stimulate tryptase release from colon mast cells following both 15 minutes and 35 minutes incubation periods. It was concluded that H1 and H2 histamine receptor antagonists were able to inhibit histamine induced tryptase release from colon mast cells. This not only added some new data to our hypothesis of self-amplification mechanisms of mast cell degranulation, but also suggested that combining these two types of antihistamine drugs could be useful for the treatment of inflammatory bowel disease (IBD).

Coupling of palmitate to ovalbumin inhibits the induction of oral tolerance

Oral tolerance is a phenomenon that may occur in animals exposed to protein antigens for the first time by the oral route. They become unable to produce immune responses at the levels normally observed when they are immunized parenterally with antigen in the presence of adjuvants. Lipids have been used as adjuvants for both parenteral and oral immunization. In the present study we coupled ovalbumin with palmitate residues by incubating the protein with the N-hydroxysuccinimide palmitate ester and tested the preparation for its ability to induce oral tolerance. This was performed by giving 20 mg of antigen to mice by the oral route 7 days prior to parenteral immunization in the presence of Al(OH)3. Mice were bled one week after receiving a booster that was given 2 weeks after primary immunization. Specific antibodies were detected by ELISA. Despite the fact that the conjugates are as immunogenic as the unmodified protein when parenterally injected in mice, they failed to induce oral tolerance. This discrepancy could be explained by differences in the intestinal absorption of the two forms of the antigen. In fact, when compared to the non-conjugated ovalbumin, a fast and high absorption of the lipid-conjugated form of ovalbumin was observed by "sandwich" ELISA.

Effects of antithrombin III and antivenom on procoagulant activity of Russell's viper venom in a whole blood model.

The procoagulant activities of Russell's viper venom were assessed in an in vitro whole blood model. Sequential samplings showed that the generation of fibrinopeptide A (FPA), a marker of thrombin activity, and platelet factor 4 (PF4), a marker of platelet activity, exhibited bi-phasic kinetics with an initial slow phase followed by a rapid phase of secretion. In the presence of Russell's viper venom, the generation of both FPA and PF4 was accelerated with the bi-phasic kinetics of PF4 being maintained while that of FPA completely disappeared. Administration of either antivenom (1,600 ng) or 10 IU antithrombin III (AT-III) had no antagonistic effect against the venom but combination of both resulted in a significant prolongation of both FPA and PF4 release (p < 0.05). High dose AT-III (20 IU) resulted in normalization of both FPA and PF4 kinetics and serial levels of both parameters were lower than those treated with the combined regimen, although these were not statistically significant. Unlike the untreated venom activated whole blood, there was no clot formation following treatment with either the combined regimen or high dose AT-III. The results of this study suggested that the effect of Russell's viper venom on the clotting cascade is more potent and direct than that on platelet activity. There were complementary effects between antivenom and AT-III is controlling of both FPA and PF4 release induced by the venom. Furthermore, in this in vitro experiment, AT-III alone when administered in a sufficient dose, abolished the procoagulant effects of Russell's viper venom.