Effect of weight gain during pregnancy on heart rate variability and hypotension during caesarean section under spinal anaesthesia.

The purpose of this study was to assess the effect of antenatal weight gain on baseline heart rate variability and incidence of hypotension in singleton parturients with a normal pre-pregnancy body mass index, presenting at term for elective caesarean section under spinal anaesthesia. Sixty-six parturients, of ASA physical status 1-2, were allocated to one of three groups according to their weight gain during pregnancy: < 11 kg; 11-16 kg; and > 16 kg. Mean (SD) approximate entropy of baseline heart rate was significantly higher in the < 11 kg group (0.27 (0.11)) compared with the 11-16 kg group (0.14 (0.08)) and the > 16 kg group (0.14 (0.07)) (both p < 0.001). The incidence of hypotension in the < 11 kg group (17/22; 77%) was significantly higher than in the 11-16 kg group (7/22; 32%) (p = 0.006) and the > 16 kg group (8/22; 36%) (p = 0.01). We conclude that weight gain < 11 kg during pregnancy is associated with increased baseline heart rate variability and a higher incidence of hypotension at the time of elective caesarean section under spinal anaesthesia.

Caquexia cancerosa em modelo experimental rato nude atímico/tumor humano KB / Cancerous cachexia in athymic nude rat experimental model/human tumor KB

1. Newborn anthymic nude rats, innoculated with KB human tumor, normally develop a great level of tumoral taken. With the augmentation in volume of the tumoral mass, animals may enter in a cachetic state that leads them to death. 2. However, proportionally to the total of days of observation, the number of rats that enter in cachexia was significantly greater than in the group that did not develop growth of tumoral mass post-innoculum. 3. This fact may suggest that any factor produced by the organism, in an excessive amount, with the aim to hinder the development of the tumoral mass, ha d a parallel effect strondgly cachetizing. 4. Relevant is the fact that the production of this substance may be thymus-independent, since these animals are congenitally athymic

Acylation of subtilisin A by aryl esters: contribution to rate limitation by a physical step preceding general acid-base catalysis.

The specificity ratios kc/Km = k for subtilisin A catalyzed hydrolysis of five aryl esters of N-(methoxycarbonyl)-L-Phe (McPhe) were determined at pH 7.03 and its pD equivalent. The ratios are independent of the electronic properties of the leaving group substituent. Kinetic solvent isotope effects, Dk, increase from about 0.9 to 1.3 as leaving group ability decreases from p-nitrophenolate to p-methoxyphenolate. The k of N-(methoxycarbonyl)-L-phenylalanine p-nitrophenyl ester (NPE) with native enzyme exhibits a strong temperature dependence; delta H* = 87 +/- 3 kJ mol-1 and delta S* = 148 +/- 14 J K-1 mol-1 at 25 degrees C (H2O). The Dk with this substrate is 1.36 at 13.6 degrees C, declines to 0.89 at 25 degrees C, and then increases to 1.04 at 39.4 degrees C. Above neutral pH(D), with McPhe NPE as substrate, the dependence of k is for the dissociated form of a single base of pKapp = 7.38 +/- 0.03 in H2O and 7.67 +/- 0.03 in D2O. The pKapp values are apparently those of the uncomplexed native protein. By contrast, k of 3-phenylpropanoic acid (Prop) p-nitrophenyl ester exhibits a weaker temperature dependence; delta H* = 20 kJ mol-1 and delta S* = -90 J K-1 mol-1 (H2O) at 25 degrees C. The Dk are larger than those for McPhe NPE, decreasing from 1.99 at 20.5 degrees C to 1.74 at 46.1 degrees C. These results, combined with those of previous studies, are consistent with limitation of k by at least two processes.(ABSTRACT TRUNCATED AT 250 WORDS)

Preparation and 13C NMR characterization of [[epsilon-13C] methionine-192]-alpha-chymotrypsin. The demethylation of [S-[13C] methylmethionine-192]-alpha-chymotrypsin by an active site-directed thiol.

Met-192 forms part of the binding crevice of alpha-chymotrypsin. The aim of this investigation was to find a nucleophile that would displace a methyl group from the sulfonium cation of [S-[13C]methylmethionine-192]-alpha-chymotrypsin without disrupting the five disulfide bridges of the protein, thereby producing [[epsilon-13C]methionine-192]-alpha-chymotrypsin, an isotopically enriched version of the native enzyme desirable for 13C NMR studies. Treatment of [S-methylmethionine-192]-alpha-chymotrypsin with mercaptoethanol and dithiothreitol failed to produce the latter protein, as deduced from elution profiles of reaction mixtures chromatographed on affinity columns of immobilized lima bean trypsin inhibitor. In contrast, when [S-methylmethionine-192]-alpha-chymotrypsin was incubated in a 3.0 mM solution of the active site-directed reagent 2-mercaptoacetyl-4'-methoxyanilide at pH 8.6 and 5 degrees C for 48 h, affinity chromatograms indicated the presence of a protein corresponding to native alpha-chymotrypsin. Upon repeating the experiment with [S-[13C]methylmethionine-192]-alpha chymotrypsin, we isolated in 40% yield a protein which was identified as [[epsilon-13C]methionine-192]-alpha-chymotrypsin by a combination of 13C NMR and chemical criteria. This work represents the first active site-directed demethylation of an S-[13C]methylmethionine residue at the binding site of an enzyme.

Residual esterase activity of lima bean inhibitor-binding anhydrochymotrypsin preparations.

A search for the source of the residual esterase activity of crude lima bean protease inhibitor-binding anhydrochymotrypsin preparations was undertaken. The preparations were found to contain about 40% of protein that possesses 1% (kc/Km) to 12% (kc) of the esterase activity of alpha-chymotrypsin. The active protein was isolated by affinity chromatography on soybean trypsin inhibitor-Sepharose. It appears to be an anhydroenzyme or a mixture of a limited number of anhydroenzymes in which a serine other than the catalytically essential serine-195 of the native enzyme has been converted to dehydroalanine.

Acylation of subtilisin Carlsberg by phenyl esters.

Approximate Hammett reaction constants rho calculated from k2/K8 values of several phenyl esters of N-acetyl-L-phenylalanine, hippuric acid, and beta-phenylpropionic acid are 0.0, 0.4, and 1.0 respectively. To determine whether the lack of substituent effect of k2/K8 with the N-acetyl-L-phenylalanine esters is a result of substituent-insensitive k2 or rate-limiting association of enzyme and substrate, pH-k2/K8 deependences and solvent deuterium isotope effects were determined for certain of the substrates and compared with those found with the corresponding hippurates and beta-phenylpropionates. In the pH range 5 to 8, k2/K8 of the phenyl and 4-nitrophenyl esters of each series is dependent upon the unprotonated form of an enzymatic base of apparent pKa approximately 7.4, identical with the pKa found for the free enzyme. With the phenyl esters of each substrate class, k2/K8 decreased by 2 to 3 times in deuterium oxide compared with water. The results suggest that a step involving a general base-catalyzed proton transfer, almost certainly k2, is rate-limiting with the N-acetyl-L-phenylalaninates, as well as the hippurates and beta-phenylpropionates. Attack by the protein on the latter substrates is prediminantly nucleophilic, judged by the similarity of rho in the enzymatic and reference hydroxide ion-catalyzed hydrolyses. The power rho values for the N-acetyl-L-phenylalaninates and hippurates could result from an electrophilic component in their hydrolytic mechanisms.