Showing papers by "Federal University of Rio de Janeiro published in 1985"

Dynamic Generalized Linear Models and Bayesian Forecasting

Abstract: Dynamic Bayesian models are developed for application in nonlinear, non-normal time series and regression problems, providing dynamic extensions of standard generalized linear models. A key feature of the analysis is the use of conjugate prior and posterior distributions for the exponential family parameters. This leads to the calculation of closed, standard-form predictive distributions for forecasting and model criticism. The structure of the models depends on the time evolution of underlying state variables, and the feedback of observational information to these variables is achieved using linear Bayesian prediction methods. Data analytic aspects of the models concerning scale parameters and outliers are discussed, and some applications are provided. Dynamic Bayesian models are developed for application in nonlinear, non-normal time series and regression problems, providing dynamic extensions of standard generalized linear models. A key feature of the analysis is the use of conjugate prior and...

Establishment of a continuous cell line from fibrotic schistosomal granulomas in mice livers

Abstract: A continuous murine cell line (GRX) was obtained from fibrotic granulomas induced in C3H/HeN mice liver by experimental infection withSchistosoma mansoni. This anchorage-dependent line produces composite connective tissue/extracellular matrix, displays morphological characteristics of myofibroblasts, and can, under appropriate conditions, accumulate fat droplets. GRX cells produce viral particles of retrovirus type. We consider GRX cell line to be representative of liver connective tissue cells, responsible for fibroplasia in liver fibrotic and granulomatous reactions.

Induced Release of γ-Aminobutyric Acid by a Carrier-Mediated, High-Affinity Uptake of L-Glutamate in Cultured Chick Retina Cells

Abstract: [3H]gamma-aminobutyric acid (GABA) was taken up by cultured embryonic retina cells during the initial stages of cell differentiation. The accumulated GABA was released in the bathing medium and a transient increase in the efflux of GABA was observed when cultures were pulse-stimulated (2 min) with 0.1 mM L-glutamate but not with D-glutamate. The EC50 for L-glutamate to evoke [3H]GABA release was approximately 15 microM. This value is close to the Km for high-affinity uptake of L-glutamate by retina cells. When Na+ ions were replaced by Li+ ions, L-glutamate-induced release of GABA was abolished. Moreover, L-[14C]glutamate uptake by retina cells was significantly reduced when NaCl was replaced by LiCl in the incubation medium. L-Glutamate elicited release of GABA was Ca2+ independent, and was observed when Ca2+ was replaced by Co2+ or when Mg2+ ions were increased to 10 mM concentration. D-Aspartate, which is taken up by the same high-affinity uptake mechanism as L-glutamate, induced an increase in [3H]GABA efflux comparable to L-glutamate. The addition of unlabeled GABA to the medium also promoted the release of accumulated [3H]GABA. However, GABA was twofold less effective than L-glutamate in eliciting [3H]GABA release. The addition of both GABA and L-glutamate to the incubation medium indicated that [3H]GABA efflux due to L-glutamate and GABA was additive. L-Aspartate also promoted an increase in the efflux of [3H]GABA accumulated by retina cells. However, L-aspartate effect was significantly decreased in the absence of Ca2+ or when Na+ ions were replaced by Li+. Our results indicate that at least three releasable pools of GABA are present in the chick embryo retina cells: (a) a GABA-promoted GABA release-homoexchange, (b) a Ca2+-dependent L-aspartate-promoted release, and (c) a Ca2+-independent, Na+-dependent L-glutamate-evoked release. In addition, our data strongly suggest that the L-glutamate-promoted GABA release is due to a process of exchange of L-glutamate with GABA, which may play a fundamental role in the fine control of the excitability of local circuits in the retina.

Platelet release reaction and aggregation induced by canatoxin, a convulsant protein: evidence for the involvement of the platelet lipoxygenase pathway.

Abstract: Canatoxin is a toxic protein isolated from Canavalia ensiformis seeds. It induces death preceded by convulsions of spinal cord origin and also produces in vitro aggregation of platelets in rabbit, human and guinea-pig plasma. The aggregating effect is dose-dependent at nanomolar concentrations. Rabbit platelets pretreated with canatoxin became refractory to a second exposure to this protein or to collagen, but were still responsive to ADP, Paf-acether or arachidonic acid. [14C]-5-hydroxytryptamine was released from pre-labelled platelets on stimulation with canatoxin. Washed rabbit platelets, but not thrombin-degranulated ones, aggregated on stimulation with canatoxin provided that fibrinogen was added before the toxin. Canatoxin's pro-aggregating activity was inhibited by mepacrine, EDTA, caffeine, prostacyclin, adenosine monophosphate and also by the ADP scavenger system, creatine phosphokinase/creatine phosphate. Furthermore, 3-amino-1-[m-(trifluoromethyl)-phenyl]-2-pyrazoline (BW 755C), eicosatetraynoic acid (ETYA) and nordihydroguaiaretic acid (NDGA) were potent inhibitors of canatoxin-induced aggregation. In contrast, no inhibition was seen with indomethacin. The data indicate that canatoxin is mainly a release-reaction-promoting agent, being devoid of any direct aggregating activity. Thus the aggregation is totally dependent on the release of ADP. Furthermore, canatoxin-induced platelet activation is probably dependent on platelet phospholipase A2 and lipoxygenase activity but is not dependent on cyclo-oxygenase products or the release of Paf-acether.

Chagas' disease: serodiagnosis with purified Gp25 antigen.

Abstract: Development of a highly specific test system for the diagnosis of Chagas' disease (CD) was sought using Gp25, a surface glycoprotein recently isolated from Trypanosoma cruzi culture forms. Radioimmunoprecipitation assays were performed to screen 567 sera for IgG antibodies to Gp25. Correct diagnosis was attained in 97.8% of the 321 sera collected from chagasic patients in several endemic areas of South America. Sera from patients with various clinical forms of chronic disease displayed similar levels of antibodies (Abs) to Gp25. Moreover, there was little cross-reactivity when assayed against 246 sera from non-chagasic individuals, including 105 samples from individuals infected with unrelated trypanosomatids. Cross-reactivity was found in two such sera; these were used to identify a minor protein contaminant as the nonspecific antigen. Residual cross-reactive molecules were eliminated from Gp25 by affinity purification on Concanavalin A (Con A) columns. We recommend this antigen-antibody system for use in routine screening of blood donors.

Leishmaniose visceral na cidade do Rio de Janeiro - Brasil

Abstract: A recente ocorrencia de casos humanos e caninos de leishmaniose visceral, autoctones de areas peri-urbanas da cidade do Rio de Janeiro, a partir de 1977, motivou pesquisadores da Escola Nacional de Saude Publica e do Instituto Oswaldo Cruz da Fundacao Oswaldo Cruz (FIOCRUZ), da Universidade Federal do Rio de Janeiro, da Universidade Federal Rural do Rio de Janeiro, da Secretaria Municipal da Saude do Rio de Janeiro e da Superintendencia das Campanhas do Ministerio da Saude (SUCAM-RJ), a participarem de um programa de estudo dessa zooantroponose, visando a uma abordagem ecologica, epidemiologica, parasitologica, imunologica, clinico-terapeutica e de avaliacao das medidas de controle adotadas. Resultados gerais dessas pesquisas sao apresentados na presente comunicacao.

Extended thermodynamics of fluids and virial equations of state

Abstract: Dans la theorie de thermodynamique generalisee de Liu et Muller en plus des densites de masse, de moment et d'energie, on prend le deviateur de contrainte et le flux thermique comme champs de base. Equations de champs en thermodynamique generalisee. Principes physiques de la theorie constitutive. Relation constitutives. Equations d'etat pour les gaz. Coefficients du viriel

The finding of Enterobius vermicularis eggs in pré-Columbian human coprolites

Abstract: Enterobius vermicularis eggs were found in human coprolites collected in the archaeological site of Caserones, Tarapaca Valley, Chile, dating from 400 BC to 800 AD. The human pinworm had already been found in other pre-historic archaeological sites in America, and its introduction in this continent is discussed.

Tokenless Protocols for Fiber Optic Local Area Networks

Abstract: A family of LAN (Local Area Network) protocols is presented. The LAN consists of a pair of unidirectional fiber optic buses to which stations are connected via passive taps. The protocols provide round-robin bounded delay access to all stations. Contrary to most roundrobin access schemes, the protocols do not require transmission of special packets (tokens); rather, they simply rely on the detection of bus activity at each station. The performance of these protocols in various traffic conditions and system configurations is evaluated via analysis and simulation.

Epidemiology of neural tube defects in South America.

Abstract: We present data from the Latin American Collaborative Study of Congenital Malformations (ECLAMC) on prevalence rates and etiologic factor associations in neural tube defects. Two series of data are analyzed: the A series, including 740, 139 consecutive infants born in the 1967–1979 period suitable for secular trend analysis and case-control study of risk factors; and the B series, including 255, 834 consecutive stillborn and liveborn infants of the 1980–1982 period suitable for prevalence rate analysis. Anencephaly was registered in 6.0/10,000 births, spina bifida aperta in 6.2/10,000 births, and cephalocele in 2.4/10,000 births. A stable secular trend was observed for the frequency of all three neural tube defect types. Spina bifida was more frequent in Chile than in the rest of South America. No differences in prevalence rates were seen between tropical and non tropical areas. Parental consanguinity and environmental prenatal factors including maternal illnesses, drug intake, and radiation exposure were found in association with anencephaly and spina bifida.

Developmental genetics of the retina: evidence that the pearl mutation in the mouse affects the time course of natural cell death in the ganglion cell layer.

Abstract: The time course of natural cell death was studied postnatally in the ganglion cell and inner plexiform layers of the retina in the developing mouse. We examined congenic wild-type, albino and pearl mutants from birth to 12 days of age. In both wild-type and albino mice, natural cell death proceeded with an increasing rate from birth to a peak 6 days after birth, and with a decreasing rate thereafter. In contrast, cell death in pearl mutants proceeded with essentially a decreasing rate postnatally. The populations of neurones and glial cells in the ganglion cell and inner plexiform layers of the retina were also determined in adult mice. It was shown that pearl mutants had a slightly smaller number of cells in those layers than both wildtype and albino mice, and that the difference was probably due entirely to the numbers of neurones. We conclude that the pearl mutation in the mouse affects the timing of developmental cell death, but the effect is not directly related to the amount of pigment in the eye.

Estudo morfológico comparativo de ovos e ninfas de Triatoma maculata (Erichson, 1848) e Triatoma pseudomaculata Corrêa & Espínola, 1964 (Hemiptera, Reduviidae, Triatominae)

Abstract: As an aid in the identification of vectors of Chagas' disease we have studied the structure of the eggs and morphology of nymphs by optical microscopy (OM) and scanning electron microscopy (SEM). The eggs as seen by OM show the exochorion of the body doesn't have defined areas. In SEM the exochorion of the cap appears as upholstered polygonal areas with small irregular grooves and perforations spread at random in both species. The exochorion of the body in T. maculata is upholstered with more numerous perforations on the edge visualizing the rim of the shell, spermatic groove, pseudomicropyles and micropyles; in T. pseudomaculata there are flat areas with numerous perforations. The nymphs show differences cencerning the stridulatory groove and rostrum. The stridulatory groove when seen by OM shows differences in nymphs of 1st, 2nd and 3rd intars, while 4th and 5th are similar; in SEM the differences are clear. In OM the rostrum shows typical pilosity to each species from 3rd instar. In T. maculata the setae are short and scattered on the 1st and 2nd segments and are long and numerous on the 3rd. In T. pseudomaculata the setae are similar but are short on the 3rd segment.