Showing papers by "Federal University of Rio de Janeiro published in 1975"

The cardiac muscle in the pulmonary vein of the rat: A morphological and electrophysiological study

Abstract: The pulmonary veins of albino Wistar rats were studied by means of light and electron microscopy. The media of larger veins consists of cardiac muscle fibers which extend until the vessels attain about 100 mu in diameter. This coat consists of external longitudinal fibers and internal circular fibers. The vasa vasorum are well developed and the capillaries show pseudofenestrations. The numerous adrenergic and cholinergic nerve endings do not form typical motor end-plates as seen in skeletal muscles. The ultrastructure of these media muscle fibers is similar to that of the rat hearts. The smooth muscle layer of larger pulmonary veins is not continuous as it is in smaller veins where it forms cushions. Comparison of albino rats and other rodents reveal striking differences. Action potential shape and propagation velocity (0.5-1.2 m/s) along the myocardial coat of the pulmonary vein were similar to those observed in the left atrium and so was their sensitivity to locally applied acetylcholine. The physiological direction of propagation in rat pulmonary veins is toward the lung. This fingind lends support to the hypothesis of a rhythmic, valve-like action of the striated musculature of the pulmonary venous wall during the systole and a possible role in the capacitance of the pulmonary circulation.

An electron microscopic and cytochemical study of the cell coat of Trypanosoma cruzi in tissue cultures.

Abstract: Using the cytochemical method of Thiery, a polysaccharide surface coat was demonstrated with the electron microscope in the various developmental stages of Trypanosoma cruzi maintained in tissue cultures. The cell coat was observed on the whole surface membrane system of T. cruzi. A positive reaction, similar to that observed in the cell membrane, was also obtained in the membranes of some vacuoles in the cytoplasm of the parasites. No granules were found in the parasite which could represent reserve polysaccharides. The possible role of the cell coat in such phenomena as adhesion, agglutination, phago-and pinocytosis and antigenicity is discussed.

Trehalose synthesis during starvation of baker's yeast

Abstract: 1. Trehalose is synthesized in baker's yeast even in the absence of an exogenous carbon source. 2. Glycogen does not contribute substantially to trehalose synthesis. 3. The decrease in the amino acid pool during starvation as well as the requisite of fully derepressed mitochondria, point towards a gluconeogenic pathway of trehalose synthesis under these conditions. 4. The results contribute to the understanding of the “ripening” period which corresponds to the final stage of commercial baker's yeast production in which cells with an optimum balance of yeast properties are formed.

Anaemia in mice with concomitant Schistosoma mansoni and Plasmodium berghei yoelii infection.

Abstract: 1 1 The effect on anaemia in mice given Plasmodium berghei yoelii 3 and 5 weeks after exposure to Schistosoma mansoni cercariae, was investigated 2 2 Haematological criteria (PCV and haemoglobin levels), reticulocytosis, parasitaemia and splenomegaly were used as indices 3 3 Anaemia was severe in the animals given P b yoelii and in those with mixed infection ( P b yoelii + S mansoni ) Malaria was found to dominate the picture until the clearance of the parasitaemia The effect of the interaction between the diseases on the anaemia was nil 4 4 Toward the end of the experiment, moderate splenomegaly was observed in the mice with mixed infection

Helium adsorption on exfoliated graphite

Abstract: High precision adsorption isotherms of3He and4He on bare Grafoil and on Grafoil coated with a monolayer of argon have been measured in the temperature range 4–20 K, using a high resolution, pressure-sensitive capacitance gauge located at 4.2 K close to the sample chamber. This gauge obviated thermomolecular pressure effects and corrections. The isotherms yielded the following resultant data: The monolayer coverage Vm for4He on bare Grafoil was 0.42 cm3 (STP)/m2 and for3He on bare Grafoil was 0.395 cm3 (STP)/m2: the isosteric heat of adsorptionQst/R of the second layer of3He on bare Grafoil was 23.5 K andQst/R for3He on argon-coated Grafoil for the first layers was 47.5 K. Also, the data for3He and4He on bare Grafoil at and just aboveVm have been used by Novaco (see subsequent paper) for determination of the virial coefficients of the gas phase occuring in the early formation of the second layer.

The flow near the bow of a steadily turning ship

Abstract: The flow near the bow of a steadily turning ship is analysed using a modified slender-body theory. The rate of change of flow quantities in the longitudinal (x) direction is assumed to be greater than that implied by ‘conventional’ slender-body theory. As a consequence some features of high Froude number flow are apparent which cannot be predicted by the ‘conventional’ theory. The modified slender-body theory proposed requires the solution of a two-dimensional Laplace equation (in y and z) but its free-surface condition still involves an x derivative. A Fourier-transform method is used to solve this problem. A simple bow configuration of constant draft is analysed and numerical results for the free-surface elevation are presented.

On calculating maximal (A,B) invariant subspaces

Abstract: -Themaximal (A, B) invariantsubspacecontained in kernel C', where (A, B, C') is associatedwith the standard linear system (l), is shown to be equal,when (A, B, C') saW~es condition (6), to theintersec- tion of themaximal (A ,B ) invariant subspaces contained in kernel C;, i=l:-,m,C,'denotingtheithrowofC'

Structure and permeability of junctions in phytohemagglutinin stimulated human lymphocytes

Abstract: drogue de d6polym6riser les micro tubules cy top lasmiques est une cons6quence de son affinit6 envers les prot6ines microtubula i res 14,15. Nos r6sul ta ts i nd iquen t en outre une scission des p61es du fuseau dans des cellules ol\"1 la concent r a t i on de VLB n ' a t t e i n t pas le niveau n6cessaire k la comple te destructioi l de l ' appare i l m i to t ique (blocage en m6taphase) . La p roduc t ion d ' anaphases mul t ipola i res p e n d a n t le t e m p s qui suit la cessat ion du t r a i t eme l l t m o n t r e le progr~s des cellules mul t ipola i res au t ravers de la mi tose ;

Desnutrição experimental: resultados anátomo-patológicos e bioquímicos da administração de dietas hipoprotéicas a ratos albinos jovens

Abstract: Using a low protein diet (aproximately 2%), two experiments were performed trying to reproduce the morphologic and electrophoretic (serum proteins) findings known to ocurr in infantile malnutrition. The model shows in young albino rats the major lesion seen in humans, standing between kwashiorkor and marasmus. The consequence of the diet is well seen by the stationary body weight. Atrophic dermal lesions were seen after 30 days. The most striking lesion was a perilobular fatty liver. Hepatocellular regeneration was abortive appearing in the final stages with regressive changes. It was possible to stablish a gradation of pancreatic changes, from small zimogenic degranulation in the begining to severe acinar atrophy after 30 days of diet, with subversion of its normal frame. The intestinal changes which ended in atrophy not comparable with that of humans, correspnd to reduction in height of the mucous epithelium, hipocellularity of the lamina propria, small crypts, decreased number of mitoses, shortening of the villi giving them a resemblance of the "germ free" animals mucosal pattern. Besides this, the authors call attention for the important decrease in size and number of the goblet cells in the ileum and in the large bowel. The model also shows a lympho-histiocitic depletion, seen by the atrophy of Peyer's patches, decrease of Kuppfer cells, thymic, lumph node and spleen lymphoid depletion. The biochemical study of the serum, has revealed a low total protein and cholesterol. The electrophoretic study has shown a decrease o albumin, with A/G inversion. Alfa1 and Alfa2 globulins were increased in the deprived animals, while Beta and Gama did not show significant difference. These findings may be atributed to protein deficiency because the control groups, even those with caloric restriction, have not presented lesions or changes of the serum proteins.

Lactate dehydrogenase from the electric organ of Electrophorus electricus (L.)--isozyme analysis.

Abstract: 1. 1. Analysis of LDH isozymes from the electric organ of Electrophorus electricus (L.) was performed with Cellogel and disc electrophoresis. 2. 2. Several extracting media were employed for the enzyme analysis and only a single component with LDH activity was obtained, which had the same mobility as the muscle LDH of Electrophorus. 3. 3. Sucrose gradient ultracentrifugation analysis confirmed the presence of only one form of LDH in electric organ extracts. 4. 4. The identity of this form with muscle LDH confirms that the electric organ results from the differentiation of muscular tissue.

Compensator design based on the invariance principle

Abstract: A systematic procedure is presented for designing a compensator for a linear time-invariant multivariable system, in such a way that the resulting disturbance transfer function is nulled. The compensator is of combined feedforward and feedback type in that it is driven by the disturbances and the available system outputs.

Anisotropies of the E.S.R. spin-hamiltonian parameters of the radical H2CN in a KCl host lattice doped with K3Ir(CN)6

Abstract: One of the paramagnetic species formed by electron irradiation of KCl single crystals doped with K3Ir(CN)6 has been assigned to the radical H2CN. The electron spin resonance spectra are anisotropic, and the anisotropies in the g-factor and in the hyperfine interactions with the hydrogens and the nitrogen nuclei are measured. The results obtained are explained by supposing that the radical is rapidly rotating about the C-N axis located at the diagonal of the KCl cubic unit cell, probably occupying tetrahedral sites and associated with positive charge-compensating ion vacancies.

Nalidixic Acid and Macromolecular Metabolism in Tetrahymena pyriformis: Effects on Protein Synthesis

Abstract: A study on the effect of nalidixic acid on macromolecular metabolism, particularly of protein, in Tetrahymena pyriformis was performed. It was shown that the compound is a potent inhibitor of deoxyribonucleic acid, ribonucleic acid, and protein synthesis for this organism. A conspicuous breakdown of polysomes, accompanied by the accumulation of 80 S ribosomes, occurred in cells incubated for 10 min with the drug; polysome formation was prevented. The accumulating 80 S particles were shown to be run-off ribosomal units. The incorporation of amino acids by a cell-free system is not affected by nalidixic acid. In nonproliferating cells the incorporation was also not prevented, unless the cells were previously incubated with the drug. These results are discussed in terms of the possible mechanism of action of nalidixic acid in T. pyriformis .

Toxicity of 4-nitroquinoline 1-oxide for Crithidia fasciculata.

Abstract: SYNOPSIS Growth inhibition of Crithidia fasciculata by 4-nitroquinoline 1-oxide (NQO) was observed in defined and complex media at 28 C. Aromatic amino acids, cysteine, and nicotinic acid, among several other substances, were ineffective in overcoming NQO toxicity. Dicoumarol and bovine albumin reversed NQO inhibition. While bovine albumin probably acted by the extra-cellular binding of NQO, dicoumarol inhibited the activity of DT-diaphorase, which reduces NQO to 4-hydroxyaminonitroquinoline 1-oxide (HAQO). The DT-diaphorase from C. fasciculata had the same characteristics as the enzyme from rat liver. The specific protection by dicoumarol against NQO inhibition suggests that HAQO is the active toxic substance for C. fasciculata.

Cytogenetics of Triatominae: III - A study on male sterility induced through hybridization of Triatoma sórdida and Triatoma pseudomaculata

Abstract: Males from bilateral crosses between Triatoma sordida and Triatoma pseudomaculata were unable to give offspring, as shown by subsequent backcrosses (BC) between hybrid males and parental females. This kind of sterility indueed through interspecific hybridization seems to be due to lack of sperm migration from the bursa copulatrix to the spermateca, thus suggesting primarily failure on the part of hybrid males to produce and/or to incorporate male accessory secretions into the spermatophore bulb. Addicional proof that sterility induced in hybrid males is at the sperm level has been afforded by the spermatogenesis herein studied. The anomalous processes like; 1) prophases of spermatogonia with the chromosomes scattered in the cytoplasm, 2) first metaphases with unpaired tetrades, 3) spermatids differing in size and 4) spermatozoa of abnormal shape and generdlly of giant size, can be taken as an indicator of the degree of departure from the normal course of spermatogenesis.

Finite Moment Formulare of h-Statistics and Their Estimates.

Abstract: In this paper a method, using ordered partitions, for expressing powers and products of generalizedh-statistics as linear combination of such statistics is given. Some general formulae for obtaining moments ofh-statistics and their estimates, when sampling from a finite population, are given. Finite semiinvariant moment formulae and their estimates through weight 8 are tabulated.

Occurrence of lipoprotein lipase in the fat-body of Triatoma maculata.

Abstract: 1. 1. Lipoprotein lipase of fat-body was investigated in Triatoma maculata , a Chagas' disease vector. 2. 2. The enzyme showed to be activated by heparin, to be rat serum (lipoproteins) dependent and to require a free fatty acid acceptor (albumin). Characteristic inhibition by 1 M NaCl was also observed. 3. 3. The enzyme from T. maculata had all the characteristic features of lipoprotein lipase as compared with that from other organisms.