Showing papers by "University of São Paulo published in 1988"

Fractionation of Bothrops jararacussu snake venom: Partial chemical characterization and biological activity of bothropstoxin

Abstract: A myotoxin, bothropstoxin (BthTX), showing no detectable phospholipase A2 activity, was purified to homogeneity from the venom of the Brazilian snake Bothrops jararacussu by a combination of gel filtration on Sephadex G-75 and ion-exchange chromatography on SP-Sephadex C-25. Four phospholipases (SIII-SPI to SIII-SPIV) were also isolated, the latter showing, similarly to BthTX (SIII-SPV) myonecrotic activity. Approximate mol. wts, as determined by SDS-PAGE, and pI of SIII-SPI to SIII-SPIV are: 22,400−4.2; 15,500−4.8; 13,800−6.9; and 13,200−7.7, respectively. BthTX is a single chain protein, approximate mol. wt 13,000, with 16 half-cystine residues, pI = 8.2 and LD50 = 7.5 mg/kg (i.p.) and 4.8 mg/kg (i.v.) for 20 g mice. The ten first N-terminal amino acid residues show a significant homology to other toxins with phospholipase structure. BthTX is specifically myotoxic, contrary to crude B. jararacussu venom which, although also myotoxic, affects intramuscular arteries and veins leading to thrombosis. BthTX and SIII-SPIV also differ from toxins isolated from the venom of other Brazilian snakes which are strongly hemorrhagic.

Genotoxicity of active oxygen species in mammalian cells.

Abstract: Revue des processus chimiques conduisant a la production d'oxygene capable d'endommager l'ADN, revue des lesions de l'ADN ainsi produites et de leur reparation, des processus biologiques resultant de ces processus. La plupart des experiences ont ete realisees sur des cellules en culture de mammifere

The right to health

Abstract: No fim do seculo XX a simples declaracao de direitos nao satisfaz ao povo. Busca-se delimita-los determinando seu conteudo, para se construirem estruturas que possam garantir o direito declarado. Nessa linha analisou-se a conceituacao de saude e de direito a saude para procurar na organizacao do Brasil, Estado federal e capitalista, meios para garantir o direito a saude. A municipalizacao das acoes de saude somada a necessidade de aprovacao legislativa do Plano de Saude e a organizacao judiciaria local foram considerados elementos importantes para a efetivacao do direito a saude.

Effects of Ovarian Steroids on Vaginal Smears in the Rat

Abstract: A correspondence between the appearance of vaginal smears and the layers of the epithelium from which the cells had desquamated was established in untreated rats during the estrous cycle, in control o

Physiology and biochemistry of insect digestion: an evolutionary perspective.

Abstract: This review primarily considers those papers which provide a full description of the steps by which the ingested food is hydrolyzed in the different regions of the insect gut. It is organized on the basis of major physiological topics and evolutionary hypotheses are used to integrate the data. A comprehensive proposal on the evolution of digestive systems in insects is provided.

Recognizable Sets with Multiplicities in the Tropical Semiring

Abstract: The last ten years saw the emergence of some results about recognizable subsets of a free monoid with multiplicities in the Min-Plus semiring. An interesting aspect of this theoretical body is that its discovery was motivated throughout by applications such as the finite power property, Eggan's classical star height problem and the measure of the nondeterministic complexity of finite automata. We review here these results, their applications and point out some open problems.

A general age replacement model with minimal repair

Abstract: A general age replacement is introduced which incorporates minimal repair, planned and unplanned replacements, and costs which depend on time. Finite and infinite horizon results are obtained. Various special cases are considered. Furthermore, a shock model with general cost structure is considered.

An extended Weyl-Wigner transformation for special finite spaces

Abstract: We extend the Weyl-Wigner transformation to those particular degrees of freedom described by a finite number of states using a technique of constructing operator bases developed by Schwinger. Discrete transformation kernels are presented instead of continuous coordinate-momentum pair system and systems such as the one-dimensional canonical continuous coordinate-momentum pair system and the two-dimensional rotation system are described by special limits. Expressions are explicitly given for the spin one-half case.

Cardiovascular effects of berberine in patients with severe congestive heart failure

Abstract: Berberine, an alkaloid of the protoberberine family, has been shown to have strong positive inotropic and peripheral resistance-lowering effects in dogs with and without heart failure. To determine the acute cardiovascular effects of berberine in humans, 12 patients with refractory congestive heart failure were studied before and during berberine intravenous infusion at rates of 0.02 and 0.2 mg/kg per min for 30 minutes. The lower infusion dose produced no significant circulatory changes, apart from a reduction in heart rate (14%). The 0.2 mg/kg per min dose elicited several significant changes: (a) Decreases in systemic (48%, p less than 0.01) and pulmonary vascular resistance (41%, p less than 0.01), and in right atrium (28%, p less than 0.05) and left ventricular end-diastolic pressures (32%, p less than 0.01). (b) Increases in cardiac index (45%, p less than 0.01), stroke index (45%, p less than 0.01), and LV ejection fraction measured by contrast angiography (56%, p less than 0.01). (c) Increases in hemodynamic and echocardiographic indices of LV performance: peak measured velocity of shortening (45%, p less than 0.01), peak shortening velocity at zero load (41%, p less than 0.01), rate of development of pressure at developed isovolumic pressure of 40 mmHg (20%, p less than 0.01), percent fractional shortening (50%, p less than 0.01), and the mean velocity of circumferential fiber shortening (54%, p less than 0.01). (d) Decrease of arteriovenous oxygen difference (28%, p less than 0.05) with no changes in total body oxygen uptake, arterial oxygen tension, or hemoglobin dissociation properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Baroreceptor reflex modulation by vasopressin microinjected into the nucleus tractus solitarii of conscious rats.

Abstract: To determine whether the central vasopressinergic system at the level of nucleus tractus solitarii (NTS) modulates the reflex control of heart rate, we employed a new method for microinjection into the brainstem of conscious, freely moving rats. Baroreceptor reflex function was assessed during pressure changes induced by intravenous administration of phenylephrine (0.25-8 micrograms/kg) and sodium nitroprusside (0.5-16 micrograms/kg) in rats microinjected, through a permanent cannula into the brainstem, with saline, arginine vasopressin (AVP), or an AVP blocker. Baseline levels of pressure and heart rate were not changed by either peptide pretreatment. Restricted injection of AVP (20 ng-0.2 microliter) into the NTS attenuated the reflex bradycardia during pressure increases, with an upward displacement of the baroreceptor reflex function line (p less than 0.01) without change in the sensitivity. Local blockade of endogenous AVP, d(CH2)5Tyr(Me)AVP (1 microgram-0.2 microliter), depressed baroreceptor reflex sensitivity with intense bradycardia to either small or large pressure increases. Baroreceptor reflex control of heart rate in response to decreases in pressure was preserved during pretreatment with AVP, whereas endogenous blockade of AVP increased baroreceptor reflex sensitivity. These effects were specific to the NTS, since in another four rats there were no effects when the injections were made 1 mm above, into the cerebellum. The changes in baroreceptor reflex control of heart rate in conscious, unrestrained rats caused by administration of AVP and its endogenous blockade provide evidence that central vasopressinergic synapses at the NTS are important physiological modulators of baroreceptor reflex function.

Cold exposure rapidly induces virtual saturation of brown adipose tissue nuclear T3 receptors

Abstract: Cold exposure induces a rapid increase in uncoupling protein (UCP) concentration in the brown adipose tissue (BAT) of euthyroid, but not hypothyroid, rats. To normalize this response with exogenous 3,5,3'-triiodothyronine (T3), it is necessary to cause systemic hyperthyroidism. In contrast, the same result can be obtained with just replacement doses of thyroxine (T4) and, in euthyroid rats, the normal response of UCP to cold occurs without hyperthyroid plasma T3 levels. Consequently, we explored the possibility that the cold-induced activation of the type II 5'-deiodinase resulted in high levels of nuclear T3 receptor occupancy in euthyroid rats. Studies were performed with pulse injections of tracer T3 or T4 in rats exposed to 4 degrees C for different lengths of time (1 h-3 wk). Within 4 h of cold exposure, we observed a significant increase in the nuclear [125I]T3 derived from the tracer [125I]T4 injections (T3[T4]) and a significant reduction in the nuclear [125I]T3 derived from [125I]T3 injections (T3[T3]). The number of BAT nuclear T3 receptors did not increase for up to 3 wk of observation at 4 degrees C. The mass of nuclear-bound T3 was calculated from the nuclear tracer [125I]T3[T3] and [125I]T3[T4] at equilibrium and the specific activity of serum T3 and T4, respectively. By 4 h after the initiation of the cold exposure, the receptors were greater than 95% occupied and remained so for the 3 weeks of observation. This effect of cold was hindered by prazosin, a drug that prevents the cold-induced activation of 5'-deiodinase. We conclude that the simultaneous activation of the deiodinase with adrenergic BAT stimulation serves the purpose of nearly saturating the nuclear T3 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemosystematics of the Rutaceae: suggestions for a more natural taxonomy and evolutionary interpretation of the family

Abstract: The chemosystematics ofRutaceae is reviewed on the basis of updated surveys of various secondary metabolites and their biosynthetic derivation. A comparison of these data with the morphological and geographical differentiation clearly shows that the current taxonomic arrangement of the family is to a large extent artificial and needs improvement. Starting from obviously “natural” groups of genera (or single genera) as “basic taxonomic entities” a new system with informal tribal names is suggested. In particular, the subfamilyToddalioideae is broken up altogether and its former members are rearranged among several of the 17 provisional tribes within the subfamilyRutoideae s. lat. Phylogenetic progressions can be recognized from parallel changes of morphological characters and biosynthetic pathways to secondary metabolites. As a general trend, a stepwise replacement of benzylisoquinolines by simple and complex anthranilic acid derived alkaloids, and eventually by coumarins and/or limonoids is confirmed. The available data are summarized in a discussion of the possible evolutionary relationships among theRutaceae, with theZanthoxylum- andEvodia-tribes in a central position.

Continental Flood Volcanism From the Paraná Basin (Brazil)

Abstract: In the past years study of the continental flood volcanism in the Parana basin had been mainly concentrated in the southern regions, where thick lava sequences are well exposed. Such research essentially concerned basic geology, petrography, radiometric dating and, subordinately, petrochemistry, isotope geochemistry and paleomagnetism (cf. Almeida, 1983; Amaral et al., 1966; Amaral and Crosta, 1983; Asmus and Baisch, 1983; Compston et al., 1968; Cordani et al., 1980; Creer et al., 1965; Ernesto, 1985; Ernesto et al., 1979; Fodor et al., 1985a, 1985b; Fulfaro et al., 1982; Halpern et al., 1974; Leinz et aL, 1966; McDougall and Ruegg, 1966; Mantovani et al., 1985a, 1985b; Marimon et al., 1983; Marques, 1983; Melfi, 1967; Minioli et al., 1971; Pacca and Hiodo, 1976; Pacca and Ernesto, 1982; Ruegg, 1976; Ruegg and Amaral, 1976; Sartori et al., 1975, 1982; Sartori and Gomes, 1980; Sartori and Filho, 1983; Souza, 1983).

Photochemistry and photobiology without light.

Abstract: — This review covers the literature since 1980 on chemically and enzymatically generated electronically excited species. The emphasis lies on triplet states of carbonyl products that are derived from dioxetanes and dioxetanones as precursors or from suitable enzymatic oxygenations. Singlet oxygen, an important excited state species in biological processes, is not explicitly treated. The utilization of triplet excited carbonyl products to promote photochemical and photobiological transformations by energy transfer are of primordial interest and not the photomechanistic behavior, photophysical properties and inherent photochemical reactions of such excited state species. Thus, the coverage concentrates on photodamage of DNA and RNA, the photochemistry of flavins, vitamin D, tryptophan, arachidonic acid, chlorophyll, lipid peroxidation, urocanase activation, excitation of chlorophlasts, and the aerobic oxidation of Schiff bases derived from amino acids and proteins. The potential perspectives of employing authentic dioxetanes and enzymatically generated dioxetane intermediates as effective photon equivalents in photochemotherapy, phototoxicity, photoaffinity labeling and photogenotoxicity are pointed out, in the hope of stimulating more intensive activity in this emerging and novel bioorganic and photobiological field.

Neutrophil migration induced by inflammatory stimuli is reduced by macrophage depletion.

Abstract: Previous experiments of our group have shown that neutrophil migration induced by inflammatory stimuli is reduced by agents which block the release from macrophages of a specific factor for neutrophil migration (MNCF, [1, 2]). The present paper evaluated the influence of macrophage depletion induced by lavage of the peritoneal cavity on neutrophil migration. In both normal and thioglycollate-stimulated peritoneal cavities, lavage with saline reduced the resident macrophage population by about 80% and significantly blocked neutrophil migration induced by inflammatory stimuli such as carrageenin, zymosan and E. coli endotoxin. Peritoneal lavage, however, did not affect neutrophil migration induced by MNCF. Thus, these results support the suggestion that macrophages participate in the control of neutrophil migration induced by acute inflammatory stimuli.

Parasitic load increases and myocardial inflammation decreases in Trypanosoma cruzi-infected mice after inactivation of helper T cells.

Abstract: In order to characterize the role played by CD4 + T lymphocytes in the immunopathology of acute Trypanosoma cruzi infection, we compared the numbers of blood and tissue parasites and the heart inflammatory reaction in normal and anti-CD4 antibody-treated C3H mice. Treatment of mice with anti-CD4 mAb during acute infection markedly inhibited T-helper-cell-dependent activities, as measured by peritoneal macrophage activation and immunoglobulin secretion by splenic B lymphocytes. After in vivo inactivation of helper T cells, the number of blood and tissue parasites significantly increased, while the inflammatory cellular infiltrates of heart muscles diminished. Our results indicate that CD4 + T lymphocytes play a dual role in the immunopathology of acute experimental Chagas' disease.

Ultrastructure of trophoblast giant cell transformation during the invasive stage of implantation of the mouse embryo

Abstract: The fine structure of abembryonic and mural trophoblast cells of mouse embryos was analyzed during the initial stages of invasion of the endometrial stroma by the embryo (days 6-8 of pregnancy). On day 6 of pregnancy, most trophoblastic cells are flat and have spindle-shaped nuclei. A few large, round trophoblastic cells (giant cells) are present at the abembryonic pole. As pregnancy proceeds through days 7 and 8, the area occupied by the trophoblast becomes larger because of an increase in the trophoblastic cell population, growth of giant cells, and rearrangement of the latter cells into a network containing maternal blood. As flat cells transform into giant cells, their content of ribosomes, granular endoplasmic reticulum, Golgi complexes, lysosomelike bodies, and heterophagosomes increases. Reichert's membrane is always lined by cell bodies or by laminar processes of trophoblastic cells that are provided with small pores. Transformation of flat cells into giant cells is associated with an activation of the giant cells and their acquisition of invasive behavior.