Showing papers by "Federal University of Rio de Janeiro published in 1982"
TL;DR: In this article, simple relations are established between isotropic functions and anisotropic functions through some vectors or tensors which characterized the anisotropy group, and the results enable us to obtain representations of anisoustropy functions using the much well-known tables for representations of isotropics.
181 citations
TL;DR: Benznidazole (a nitroimidazoles derivative used for the treatment of Chagas' disease) is reduced by rat liver microsomes to the nitro anion radical, as indicated by ESR spectroscopy.
98 citations
TL;DR: An integral formulation for solving two-and three-dimensional problems governed by the scalar wave equation is presented in this paper, where the authors focus on finding an integral expression for the two-dimensional case, involving source density, initial and boundary conditions, which can be used for time stepping numerical analysis.
97 citations
TL;DR: The cyclic AMP level of 17‐day‐old chick embryo retina increased from 20 to 331 pmol/mg protein when the tissue was incubated for 20 min in the presence of 4‐(3‐butoxy‐4‐methoxybenzyl‐2‐imidozolinone) (RO 20‐1724) and the effect was observed in cultured retina cells.
Abstract: The cyclic AMP level of 17-day-old chick embryo retina increased from 20 to 331 pmol/mg protein when the tissue was incubated for 20 min in the presence of 4-(3-butoxy-4-methoxybenzyl-2-imidozolinone) (RO 20-1724). The addition of 0.5 mM-3-isobutyl-1-methylxanthine (IBMX) or 0.5 units/ml of adenosine deaminase (EC 3.5.4.4) to the medium reduced the increase of cyclic AMP content from 20 to 100 pmol/mg protein. Dipyridamole did not interfere with the rise of the retinal cyclic AMP level observed with RO 20-1724. The EC50 of 6-amino-2-chloropurine riboside (2-chloroadenosine)-elicited accumulation of cyclic AMP of retinas incubated in the presence of RO 20-1724 plus adenosine deaminase was approximately 1 microM. When retina incubation was carried out in the presence of 0.5 mM-IBMX, the 2-chloroadenosine dose-response curve was shifted to the right two orders of magnitude. Maximal stimulation of the cyclic AMP level of 17-day-old chick embryo retina incubated in the presence of 0.5 mM-IBMX was observed at 1 mM-adenosine concentration. This effect was not blocked by dopamine antagonists. Guanosine and adenine did not affect the retinal cyclic AMP level. AMP and ATP had a slight stimulatory effect. Adenosine response of embryonic retina increased sharply from the 14th to the 17th embryonic day. A similar, but not identical adenosine effect was observed in cultured retina cells.
69 citations
TL;DR: Results suggest that endocytosis is the principal mechanism of internalization of T. cruzi by macrophages, and show also that epimastigote and trypomastigotes forms ofT.cruzi have a different rate of adhesion to the macrophage surface.
Abstract: Chicken macrophages, obtained by cultivation of blood monocytes, were infected with epimastigote and bloodstream trypomastigote forms ofTrypanosoma cruzi strain Y. The percentage of macrophages containing parasites within parasitophorous vacuoles and of flagellates attached to cell surfaces was determined. By incubation of the macrophages at 4°C or in the presence of cytochalasin B it was possible to dissociate the attachment from the internalization phases in the process of infection of macrophages. Both treatments had a marked effect on the internalization of epimastigote and trypomastigote forms. Cytochalasin B treatment and placement of the macrophages at 4° C before infection inhibited this process by about 99 and 96%, respectively. These results suggest that endocytosis is the principal mechanism of internalization ofT. cruzi by macrophages. They show also that epimastigote and trypomastigote forms ofT. cruzi have a different rate of adhesion to the macrophage surface.
65 citations
TL;DR: In this article, the well-posedness of the Cauchy problem and the asymptotic behavior of solutions of the nonlinear wave equation u tt − Δu + m 2 + u(V ∗ u 2 ) = 0 in Euclidean space were studied.
50 citations
TL;DR: The influence of pressure on the behavior of different particles fluidized by nitrogen was experimentally investigated in this article, where the powders used were mostly in Geldart's group B and the pressure was varied in the range 100 to 3500 kPa.
38 citations
TL;DR: The Modulation Transfer Function (MTF) of the visual system of the opossum, D. marsupialis aurita, was determined using the amplitude of Visually Evoked Cortical Potentials (VECP) as response indicator and the average acuity value obtained was 1.25 c/deg.
36 citations
35 citations
TL;DR: Freeze-fracture techniques reveal differences in fine structure between the anterior three flagella of Tritrichomonas foetus and its recurrent flagellum and numerous fenestrations in the membrane of the Golgi complex and about 24 pores per micron2 in the nuclear membrane.
Abstract: Freeze-fracture techniques reveal differences in fine structure between the anterior three flagella of Tritrichomonas foetus and its recurrent flagellum. The anterior flagella have rosettes of 9-12 intramembranous particles on both the P and E faces. The recurrent flagellum lacks rosettes but has ribbon-like arrays of particles along the length of the flagellum, which may be involved in the flagellum's attachment to the cell body. This flagellum is attached to the membrane of the cell body along a distinct groove that contains few discernible particles. Some large intramembranous particles are visible on the P face of the cell body membrane at the point where the flagellum emerges from the cell body. The randomly distributed particles on the P and E faces of the plasma membrane have a particle density of 919/micron2 and 468/micron2 respectively, and there are areas on both faces that are devoid of particles. Freeze-fracture techniques also reveal numerous fenestrations in the membrane of the Golgi complex and about 24 pores per micron2 in the nuclear membrane.
34 citations
TL;DR: Results suggest that the hydrogenosome may be involved in the control of the intracellular concentration of Ca 2+ in T. foetus.
TL;DR: Analyses of chromium concentrations in waters, suspended particles, bottom sediments, fish (Poecilia reticulata), plants (Paspalum vaginatum, Sesuvium portulacastrum, Philoxeros vermicularis), soils and barnacles (Balanus sp.) were performed from August 1976 to September 1980 in samples collected from the Iraja River and inside its estuary in Guanabara Bay.
TL;DR: Results indicate that maltose specifically induces the production of the MAL gene-product, which, in turn, would stimulate the formation (or activation) of system II, which produces trehalose by trans-glucosylation.
Abstract: A pattern of active accumulation of trehalose during growth on glucose medium, TAC(+) phenotype, is controlled by a polymeric series of maltose fermentation (MAL) genes. An essential requirement for expression of the TAC(+) phenotype is that the MAL gene be in the constitutive state, MALc. Mutation of a constitutive MAL allele to a maltose- inducible or nonfermenting (mal) state, alters the pattern of trehalose metabolism so that little or no trehalose accumulation occurs during growth on glucose medium. The TAC(+) phenotype is obtained in MALc strains whether or not α-glucosidase formation is sensitive or resistant to carbon catabolite repression. However, trehalose accumulation is sensitive to glucose levels even in MALc strains in which α-glucosidase formation is insensitive to catabolite repression. The effects of constitutive MAL genes on trehalose accumulation cannot be accounted for by an increase in trehalose-6 phosphate synthase or a decrease in trehalase as determined in vitro. A mechanism is proposed in which the gene-product of a MAL gene serves as a common positive regulator for expression of four genes coding respectively for maltose permease, maltase, α-methylglucosidase and a component of the trehalose accumulation system.
TL;DR: The natural pyran-naphthoquinone (I,II) has been reported as an agent against Trypanosoma Cruzi and some kinds of tumors as discussed by the authors.
TL;DR: The induction and distribution of chromosomal transcripts in the polytene chromosomes of D. melanogaster and D. hydei has been investigated by indirect immunofluorescence using an antiserum directed against DNA/RNA hybrids, suggesting that in order to hybridize the RNA has to be located in its transcriptional compartment.
Abstract: The induction and distribution of chromosomal transcripts in the polytene chromosomes of D. melanogaster and D. hydei has been investigated by indirect immunofluorescence using an antiserum directed against DNA/RNA hybrids. The fluorescence was intense and occurred in most of the chromosomal subdivisions when the chromosomes were exposed to denaturing conditions and then allowed to reanneal. The extent of hybrid formation depended both on the extent of DNA denaturation and on the maintenance of RNA integrity. Fluorescence was absent from chromosomes treated with pancreatic RNase before denaturation. The velocity of the chromosomal DNA/RNA hybridization reaction and the effects of the initiation inhibitor of RNA synthesis, DRB, suggest that in order to hybridize the RNA has to be located in its transcriptional compartment. Even though overall patterns of fluorescence seem to be similar during a developmental stage, variations were observed, particularly some correlated with puff induction after ecdysone stimulation.
TL;DR: The author finds that the first metatarso-sesamoid joint is assymmetrical both in children and adults, the medial surface being larger than the lateral.
Abstract: The first metatarso-sesamoid joint is separately identified from the first metatarso-phalangeal joint and its anatomical characteristics are described from a study of one hundred anatomical specimens of normal adult and children's feet and two hundred radiographs of patients' feet.
TL;DR: Differences in the size of the constitutive heterochromatic regions were frequently found in many chromosome pairs in animals of different geographic origin, although the possibility that they are maintained as chromosome polymorphisms could not be reled out.
TL;DR: Vieira''-^ was a pioneer in the study of the clinical and epidemiologic features of BPF, and today there is no doubt that the disease was not tokelau but BPF.
Abstract: The term pemphigus brasiliensis was first introduced by Sauvages' in 1768, although the entire group of pemphigus studied by him was not true pemphigus. The true entity, pemphigus foliaceus, was described by Cazenave^ in 1844. In 1903 Paes Leme^ published a thesis on tokelau; today there is no doubt, however, that the disease was not tokelau but BPF. \"Wild fire\" is old and popular name for BPF. Vieira''-^ was a pioneer in the study of the clinical and epidemiologic features of BPF.
TL;DR: It is suggested that the trypanosomatids possess an organelle that can be considered to be a peroxisome, similar to that of Leptomonas samueli.
Abstract: Leptomonas samueli possesses in its cytoplasm a membrane-bounded organelle which can reach a length of 2.8 microns and a diameter of 0.2 microns. Catalase activity, which is inhibited by 3-amino-1, 2, 4-triazole, was detected at the ultrastructural level in the matrix of the organelle by using an alkaline diaminobenzidine medium. Freeze-fracture studies showed the presence of a large number of intramembranous particles on both the P and the E faces of the membrane of the organelle. Based on these data as well as on previous observations, it is suggested that the trypanosomatids possess an organelle that can be considered to be a peroxisome.
TL;DR: Study of the distribution of DNA·RNA hybrids on polytene chromosomes with the aid of a goat antibody against DNA· RNA hybrids using the immunofluorescence technique shows that hybrid fluorescence is confined to transcriptionally active regions.
Abstract: We have studied the distribution of DNA·RNA hybrids on polytene chromosomes with the aid of a goat antibody against DNA· RNA hybrids using the immunofluorescence technique. Fixed polytene chromosomes of the sciarid Trichosia pubescens (Diptera) show distinct, stage-specific labelling patterns throughout larval development. Controls for the staining procedure — including preincubation with hybrid-specific endoribonuclease H — prove that DNA·RNA hybrids are present on fixed chromosomes. They are revealed only under mild fixation conditions which do not efficiently immobilise all chromosomal proteins, indicating that some proteins have to be removed to make the antigens accessible to antibody. Certain fixation conditions may also cause local denaturation of chromosomal DNA, and some hybrids may possibly form during specimen preparation. After incorporation of radioactive uridine, a combination of phase contrast, fluorescent, and autoradiographic images of one and the same chromosomal preparation demonstrates that hybrid fluorescence is confined to transcriptionally active regions. Two puff classes can be distinguished. The first binds antibody and includes most RNA puffs and all DNA puffs so far studied; the second, comprising some RNA puffs, does not show bright fluorescence in spite of the fact that RNA synthesis is high as revealed by 3H-uridine incorporation. DNA·RNA hybrids are not found at DNA puff sites during the DNA amplification period; these sites contain detectable hybrids only when transcription is taking place. — Combination of the fluorescent technique with its excellent resolution and autoradiography should be helpful in studying detailed topological aspects of transcriptionally active chromosomal regions.
TL;DR: The relative genome sizes and the proportions of X- and Y-chromosomal DNA in Drosophila hydei, D. neohydei and D. eohy dei were measured by microspectrophotometry and some implications of the results with respect to genome evolution in these species are discussed.
Abstract: The relative genome sizes and the proportions of X- and Y-chromosomal DNA in Drosophila hydei, D. neohydei and D. eohydei were measured by microspectrophotometry. Some implications of the results with respect to genome evolution in these species are discussed.
TL;DR: Yeasts were found concentrated at the sediment surface and with the highest counts at the most polluted site, and species like Rhodotorula rubra related to basidiomycetous fungi were found in relatively low numbers.
Abstract: Yeasts were found concentrated at the sediment surface and with the highest counts at the most polluted site. Candida krusei, Pichia membranaefaciens and similar species typically forming rugose colonies with radiating ridges were the prevalent yeasts in these sediments, and species like Rhodotorula rubra related to basidiomycetous fungi were found in relatively low numbers.
TL;DR: Growth and enterotoxin production by Staphylococcus aureus strain FRI-996, producer of enterotoxins A, B and D, were determined over a 24-h period.
TL;DR: Results indicate that the surface of T. foetus contains both negatively and positively charged dissociating groups.
Abstract: The surface charge of Tritrichomonas foetus was evaluated by means of the binding of colloidal iron hydroxide particles at pH 1.8 and cationized ferritin particles at pH 7.2 to the cell surface, as visualized by electron microscopy and by direct measurements of the electrophoretic mobility (EPM), of cells suspended in solutions of different ionic strength and pH. At pH 7.2, T. foetus has a negative surface charge with a mean EPM of -1.03 micrometer . s-1 . V-1 . cm. At lower pH, there is a decrease in the negative surface charge with an isoelectric point at pH 1.2. At higher pH (greater than 9.0), there is an increase in the surface charge reaching an EPM of -2.5 micrometers . s-1 . V-1 . cm. These results indicate that the surface of T. foetus contains both negatively and positively charged dissociating groups. Binding of colloidal iron hydroxide and cationized ferritin particles throughout the cell surface of the protozoon was observed. Treatment of T. foetus with neuraminidase or trypsin reduced significantly the EPM of the cells. Enzyme-treated cells recovered their normal EPM when incubated for 6 h in fresh culture medium by a process that is inhibited by puromycin.
TL;DR: In this article, it is proposed that the glc1 mutation affects a regulatory system, probably involving a protein kinase and/or protein phosphatase, which regulates glycogen synthase and trehalase.
Abstract: The recessive, nuclear gene mutation glc1, which causes glycogen deficiency in Saccharomyces cerevisiae, is highly plciotropic. Studies of the inheritance of glc1 revealed two classes of phenotypic characteristics: I. Traits invariably associated with the mutant gene and II. Traits whose expressions require the presence of glc1 and one or more additional genes. Class I traits include glycogen deficiency and the loss of capacity to accumulate trehalose in nonproliferating conditions. Traits in the second class include a decreased rate of growth on ethanol medium, a deficiency in cytochrome a.a
3 and an enhanced accumulation of pigment, probably a metalloporphyrin. Constructed strains containing both glc1 and the constitutive maltose fermentation gene MAL4
0
can accumulate trehalose but not glycogen during growth on glucose. However, accumulated trehalose is degraded when cells are exposed to nonproliferating conditions. It is proposed that the glc1 mutation affects a regulatory system, probably involving a protein kinase and/or protein phosphatase, which regulates glycogen synthase and trehalase. Independent regulation of trehalose synthesis by a system controlled by MAL4
0
is indicated.
TL;DR: Analysis of chromosomes of the Rhesus monkey has shown that karyotype standardization in the primates should not follow an anthropomorphic criterium because this may lead to inevitable incongruities.
TL;DR: It is concluded that, with increasing wavelength, damage induced by solar UV radiations becomes increasingly less susceptible to repair systems induced by far‐UV (pyrimidine dimers) and that this type of inducible repair system is no longer induced by wavelengths longer than 313 nm.
Abstract: The susceptibility of bacteriophage damaged by solar-ultraviolet (UV, 290-380 nm) radiations at denned wavelengths and by radiation at a visible wavelength (405 nm) to the Weigle reactivation system induced by far-UV (254 nm) irradiation of the host cell has been studied in a repair competent strain of Escherichia coli. The sector of inducible repair diminishes with wavelength, being very small after 313 nm irradiation and absent after irradiation at longer wavelengths. However, irradiation of bacteria at wavelengths as long as 313 nm induces a bacteriophage reactivation system as effectively as radiation at 254 nm in both the repair competent and an excision deficient host cell. At longer wavelengths pre-irradiation of the repair competent host cell enhances reactivation of 254 nm irradiated bacteriophage but the reactivation is smaller and the process quite distinct from that induced in the 254-313 nm region. We conclude that, with increasing wavelength, damage induced by solar UV radiations becomes increasingly less susceptible to repair systems induced by far-UV (pyrimidine dimers) and that this type of inducible repair system is no longer induced by wavelengths longer than 313 nm.
TL;DR: The representation of the visual field in the upper layers of the opossum's superior colliculus was studied by recording the response of multi-units to visual stimulation and revealed that the rostral region contains a representation of 40 ° of the ipsilateral field.
Abstract: The representation of the visual field in the upper layers of the opossum's superior colliculus was studied by recording the response of multi-units to visual stimulation. Overall, the visual topography is similar to that of other non-primate mammals. Along the horizontal meridian the magnification factor decreases assymetrically about the vertical meridian, falling more abruptly in the region of the representation of the ipsilateral hemifield. The colliculus may be divided into three parts on the basis of the projections from the retina: a rostral region that does not receive any ipsilateral retinal afferents, a region that receives binocular retinal projections and a monocular region that receives only contralateral retinal input. Electrophysiological recording revealed that the rostral region contains a representation of 40 ° of the ipsilateral field. The representation of the vertical meridian forms the border between the rostral region and the binocular region and the representation of the 40–45 ° longitude meridian forms the border between the binocular and monocular regions.
TL;DR: In this paper, the authors present the solution of the field equations in the presence of a generalized dust cylinder under rigid rotation, where an equation of state Σ = eϱ is assumed.
Abstract: We present the solution of Einstein’s field equations in the presence of a generalized dust cylinder under rigid rotation. An equation of state Σ = eϱ is assumed. The properties of the solution are discussed.
DOI•
29 Jan 1982TL;DR: In this paper, a littoral sand transport expression is proposed, relating littral transport rate to surf similarity parameter and hence to wave energy dissipation rate, which indicates that the "constant" in the CERC formula is dependent on the mobile bed beach slope and on the breaker index.
Abstract: This paper is an analysis of two sets of experimental results on littoral sand transport. A littoral sand transport expression is proposed, relating littoral transport rate to surf similarity parameter and hence to wave energy dissipation rate. The expression indicates that the "constant' in the CERC formula is dependent on the mobile bed beach slope and on the breaker index. The expression is also compared with some of the few published field measurements.