Kinetics of the reaction of alkylamines with 7,7,8,8-tetracyanoquinodimethane (TCNQ) in organic solvents

The following sequence of substitution reactions was studied spectrophotometrically in organic solvents: RNH2 + TCNQ →-HCN 7-substituted TCNQ →-HCN +RNH2 7.7-disubstituted TCNQ where R = butyl, octyl, dodecyl, and hexadecyl. The production of 7-(alkylamino)-7,7,8-tricyanoquinodimethanes proceeds via the formation of the anion radical of TCNQ (TCNQ-·) whose rate of appearance was found to be a function of the chain length of R, reaching a maximum for octylamine. The formation of TCNQ-· was sensitive to the solvent polarity and electron-donor power and was associated with a small enthalpy and a highly negative entropy of activation. Above a certain [C8H17NH2] the rate of disappearance of TCNQ-· was independent of the amine concentration, and the reaction had a much higher enthalpy and entropy of activation. The occurrence of tautomerism precluded an investigation of the conversion of 7-(octylamino)-7,8,8-tricyanoquinodimethane into 7,7-bis(octylamino)-8,8-dicyanoquinodimethane. A study of the reaction of octylamine with 7-morpholino-7,8,8-tricyanoquinodimethane (which does not exist in tautomeric forms) showed that the second substitution step proceeds with the same mechanism as the first one. The only difference between the two compounds (TCNQ and its monosubstituted morpholino derivative) is one of reactivity. © 1985 American Chemical Society.

Interstitial long-arm deletion of chromosome 7 and ectrodactyly

An interstitial deletion of 7q21 was found in a boy with mental retardation, microcephaly, convergent strabismus, micrognathia, genital anomalies, and other findings, including ectrodactyly.

SISTEMAS QUIMILUMINESCENTES COM PEROXIDASE (EC:1.11.1.7) E SUAS APLICACOES EM ANALISES CLINICAS

The enzyme horseradish peroxidase HRP (EC:1.11.1.7), has both acid and basic isoenzymes, catalyses a wide range of reactions (acting as an oxiredutase or an oxidase) and is thought capable of one- or two-electrons oxidations depending on the substrate employed. Today, the methodology for these assay can be chemiluminescent reactions and enhanced chemiluminescent. The enhanced chemiluminescent assay with system HRP, luminol, peroxide and an enhancer has provided the basis for a convenient and sensitive assay for peroxidase and peroxidase conjugates, DNA probe and blotting assay. It is particularly more advantageous than the others, because is very rapid, more sensitive (attomoles), easy to do and technically simple, and is relatively specific for HRP (reduces the effect of the interference).

Papel da regiao AV3V no choque septico experimental em ratos tratados com NaCl 7,5%

The effect of intravenous infusion of hypertonic saline (HS) on the recovery of mean arterial pressure (MAP) during septic shock was studied in sham-operated rats and in rats with electrolytic lesion in the anteroventral third ventricle (AV3V) region. Our results show that intravenous HS infusion in rats treated with endotoxin (Etx) partially restores MAP, but when we have a severe shock produced by Etx, HS was not able to reverse the hypotension. We also show that the integrity of the AV3V region is essential for the protective action of HS in endotoxin shock. It is possible that NO production contributes to the deleterious effect of endotoxin. So, the unraveling of the release of NO by the vascular endothelium and their role as regulators of vascular tone is increasing our understanding of the physiology and pathophysiology of the cardiovascular system and will therefore enhance the possibilities of preventing and treating endotoxin shock.

Adenocarcinoma in females detected in serous effusions: Cytomorphologic aspects and immunocytochemical reactivity to cytokeratins 7 and 20

OBJECTIVE: To investigate the usefulness of assessing the immunoreactivity of cytokeratins 7 (CK7) and 20 (CK20) as well as several cytomorphologic parameters in effusions with metastatic adenocarcinomas in the search for the primary site of the tumor. STUDY DESIGN: From the files of the Pathology Department, A. C. Camargo Hospital, we studied cytologic smears from 73 metastatic adenocarcinomas originally from the breast, 63 from the ovary, 40 from the lung and 32 from the stomach, looking for morphologic parameters that could have discriminant potential in suggesting the primary site in a routine situation, including intranuclear inclusions, prominent nucleoli, mitosis, signet-ring cells, psammoma bodies, nuclear crease, binucleation and multinucleation, papillary features, acinar profile (including ball cells) and single cells. Immunoreactions were performed with monoclonal antibodies to CK7 (OV-TL 12/30 and CK20 (Ks 20.8) and included morphologic analysis. Both analyses were studied in a blind fashion regarding the primary site of the tumors. RESULTS: Positivity ratios for breast, ovary, stomach and lung cases were 67.6%, 63.5%, 29.7% and 45.5%, respectively, for CK7 and 17.2%, 15.8%, 13.5% and 32.2%, respectively, for CK20. Discriminant analysis of morphologic and immunocytochemical parameters had an error rate of 42.9% in recognizing the primary site and a Wilk's lambda of .7290. CONCLUSION: The more efficient parameter with discriminant function was the papillary appearance showed by CK7, which should be used in further studies with a similar scope. The set of parameters used in this study were insufficient to discriminate the primary site of female adenocarcinomas in effusions with significant accuracy.

Preparation of N2, N2,7-trimethylguanosine affinity columns

2,2,7-trimethylguanosine (TMG) binding proteins from human cells were purified through TMG-affinity columns. TMG synthesis was improved and the TMG obtained was shown to be similar to the TMG in the 5' cap of the UsnRNAs. The eluates obtained with TMG-affinity chromatographies were very different from those isolated with m7G-affinity columns, thus suggesting that specific TMG- binding proteins were obtained. The fraction may be enriched with factors associated with import and/or hypermethylation of UsnRNPs.

Aryltetralone lignans and 7,8-seco-lignans from Holostylis reniformis

Aryltetralone lignans and two 7,8-seco-lignans were isolated from the acetone and hexane extracts of the roots of Holostylis reniformis, together with (-)-galbacin. Their structures were determined by spectroscopic methods. © 2004 Elsevier Ltd. All rights reserved.

Kinetics and crystal structure of human purine nucleoside phosphorylase in complex with 7-methyl-6-thio-guanosine

Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of nucleosides and deoxynucleosides, generating ribose 1-phosphate and the purine base, which is an important step of purine catabolism pathway. The lack of such an activity in humans, owing to a genetic disorder, causes T-cell impairment, and drugs that inhibit this enzyme may have the potential of being utilized as modulators of the immunological system to treat leukemia, autoimmune diseases, and rejection in organ transplantation. Here, we describe kinetics and crystal structure of human PNP in complex with 7-methyl-6-thio-guanosine, a synthetic substrate, which is largely used in activity assays. Analysis of the structure identifies different protein conformational changes upon ligand binding, and comparison of kinetic and structural data permits an understanding of the effects of atomic substitution on key positions of the synthetic substrate and their consequences to enzyme binding and catalysis. Such knowledge may be helpful in designing new PNP inhibitors. © 2005 Elsevier Inc. All rights reserved.

Peroxidase enzyme (EC.1.11.1.7) activity as an indicator of water stress in sweet pepper plants

The present work was carried out at the Faculdade de Ciências Agronômicas - UNESP, Botucatu, SP. The purpose of the study was to evaluate the physiological and biochemical behavior of sweet pepper (Capsicum annuum L.) plants under different soil water availability conditions and the efficiency of the peroxidase (EC. 1.11.1.7) activity as an indicator of water stress in plants. Sweet pepper plants were grown for 230 days after transplanting of seedlings. The experiment was arranged in a completely randomized experimental design with 4 treatments, two irrigation managements (50 and 1500 kPa) and two soil surface managements (presence or absence of black polyethylene covering), and six replications. Physiological activities, such as stomatal transpiration and resistance to water vapor diffusion, were evaluated, as well as biochemical activities, such as peroxidase activity and total soluble protein in foliar tissues. It was observed that soil water availability may lead to physiological and biochemical alterations in plants. Successive water stress cycles may promote the development of characteristics responsible for improving the plant tolerance to periods of low water availability. The peroxidase enzyme activity showed to be an efficient indicator of water stress in sweet pepper plants.