Showing papers by "Universidade Federal de Minas Gerais published in 1994"
TL;DR: This paper presented a theoretical perspective on teaching and learning science in the social setting of classrooms, informed by a view of scientific knowledge as socially constructed and by a perspective on the learning of science as knowledge construction involving both individual and social processes.
Abstract: The view that knowledge cannot be transmitted but must be constructed by the mental activity of learners underpins contemporary perspectives on science education. This article, which presents a theoretical perspective on teaching and learning science in the social setting of classrooms, is informed by a view of scientific knowledge as socially constructed and by a perspective on the learning of science as knowledge construction involving both individual and social processes. First, we present an overview of the nature of scientific knowledge. We then describe two major traditions in explaining the process of learning science: personal and social constructivism. Finally, we illustrate how both personal and social perspectives on learning, as well as perspectives on the nature of the scientific knowledge to be learned, are necessary in interpreting science learning in formal settings.
2,143 citations
TL;DR: Results show that A-779 is a potent and selective antagonist for Ang-(1-7), and data indicate that specific angiotensin receptors mediate the central and peripheral actions of Ang-( 1-7).
290 citations
TL;DR: The structural framework of the Quadrilatero Ferrifero is the result of two main deformational events as mentioned in this paper : the Transamazonian Event and the Pan-African/Brasiliano Event.
183 citations
TL;DR: The results of this study suggest that socioeconomic and nutritional factors should be considered in the prognostic evaluation of children with leukaemia in developing countries.
Abstract: One hundred and twenty eight Brazilian children with lymphoblastic leukaemia were intensively treated with a Berlin-Frankfurt-Munich based protocol. More children had a white cell count above 50 x 10(9)/l (31%) then observed in developed countries. After a median follow up of 31 months (11-58 months), the estimated probability of relapse free survival was 41% (7%) for the whole group. After adjustment in the Cox's multivariate model, malnutrition was the most significant adverse factor affecting duration of complete remission. Age above 8 years and high peripheral white cell count were also significant adverse factors. Among the nutritional indices, the height for age and weight for age z scores were both significant, whether the cut off points of z-2 or z = -1.28 were chosen to define malnutrition. A strong statistical association between the two indices was found; the contribution of height for age z score to the prediction of relapse free survival was more significant. Children with height for age z score -2. The results of this study suggest that socioeconomic and nutritional factors should be considered in the prognostic evaluation of children with leukaemia in developing countries.
160 citations
TL;DR: The results indicate that, although Ang II acts in the VLM through an AT1 receptor subtype, the cardiovascular effects produced by microinjection of Ang-(1-7) into the RVLM and CPA are mediated by a specific angiotensin receptor (AT5?).
153 citations
TL;DR: A total of 3866 patients stung by Tityus serrulatus scorpion was admitted to Hospital João XXIII, in Belo Horizonte, Brazil, over a 16-year period, with the presence of air bronchograms and a peripheral distribution suggesting that a noncardiogenic factor is also involved in the genesis of lung oedema.
149 citations
Journal Article•
TL;DR: It is demonstrated that in Belo Horizonte, Brazil, as also reported in other developing countries, H. pylori infection occurs early and increases with age, and there was no significant difference with regard to nutritional status or the presence of sewage.
116 citations
TL;DR: Paternity can be efficiently and effectively tested using multi-allelic variable number of tandem repeat (VNTR) polymorphisms and the informativeness of these hypervariable loci is so high that paternity disputes can be resolved with certainty in virtually every case.
115 citations
01 Jul 1994
TL;DR: In this article, the authors proposed to bracket the age of the Minas Supergroup with reasonable precision between about 2580 Ma and 2050 Ma on the basis of precisezircon U-Pb age determinations from both granitic rocks of the basement and detrital zircons from quartzitesand graywackes of the Proterozoic metasedimentary sequences of the Quadrilatero Ferrifero.
Abstract: It is now possible to bracket the age of the Minas Supergroup with reasonable precision between about2580 Ma. (base of the Moeda Formation) and 2050 Ma. (top of the Sabara Formation) on the basis of precisezircon U-Pb age determinations from both granitic rocks of the basement and detrital zircons from quartzitesand graywackes of the Proterozoic metasedimentary sequences of the Quadrilatero Ferrifero.Three major unconformities subdivide the stratigraphic column into three sequences. The first sequencecomprises the Moeda, Batatal, Caue and Gandarela Formations from 2580 to 2400 Ma.. The second sequencecomprises the Cercadinho, Fecho do Funil, Tabooes and Barreiro Formations (the Piracicaba Group) datedat 2400 to 2150 Ma.. The third sequence contains only the synorogenic sediments of the Sabara Formation,deposited during the Transamazonian Event between 2150 and 2050 Ma.. This event folded andmetamorphosed the Minas Supergroup for the first time.The Sabara Formation of the Piracicaba Group has very different sedimentological characteristics fromthe other formations of this group and is exceptionally thick (about 3500 m), we therefore propose to upgradeit to the rank of a Group.Zircon age histograms of the Moeda quartzite (sample QF-1) and Sabara graywacke are similar, indicatinga common Archean source, i.e. the Belo Horizonte Complex north of the Quadrilatero Ferrifero. This impliesthat sedimentation of the Minas Supergroup in the western Quadrilatero Ferrifero is autochthonous.Periods of carbonate and Iron Formation platform sedimentation (Caue, Gandarela and partly Fecho doFunil Formations) coincide with minor frequency of age plots of detrital zircons, indicating also a stabletectonic environment.Comparison of the Minas Supergroup with the Transvaal Sequence of South Africa revealscorrespondence not only in age but also in thickness, position of the major unconformities, lithologicalcompositions and in the position of gold and pyrite bearing quartz-pebble conglomerates.
110 citations
TL;DR: In this paper, social networks and daily activities of children and adolescents living and/or working on the streets of a large Brazilian city were examined, drawing on data collected through structured surveys, in-depth interviews, focus group discussions, and field observations.
Abstract: Social networks and daily activities of children and adolescents living and/or working on the streets of a large Brazilian city were examined. Drawing on data collected through structured surveys, in-depth interviews, focus group discussions, and field observations, we described street youths' family situation, social resources, institutional experiences, survival activities, and problem behaviors and investigated differences attributable to age, gender, and living situation (at home or on the street). Youngsters who lived at home and worked on the street appeared to be experiencing orderly development despite their impoverished circumstances. Youngsters who lived on the street showed hallmarks of psychological and physical risk, including parental loss, diminished social support, substance abuse, and early onset of sexual activity. Possible implications of these contextual differences for development are discussed, and directions for future research are suggested.
104 citations
TL;DR: Increased levels of activated T cells and CD5+ B cells are present in the circulation of people with chronic Chagas' disease, which are cell phenotypes that have been associated in other conditions with autoimmune, polyclonal, and hyperimmune responses.
Abstract: Whole blood preparations from patients with either the indeterminate (asymptomatic) or cardiac clinical forms of chronic Trypanosoma cruzi infection were analyzed by flow cytometry using double-labeling to identify subsets of circulating lymphocytes. Several significant differences were demonstrated between the blood lymphocyte profiles of chagasic patients and non-chagasic controls. Clear increase in the percentages and actual numbers of double-positive cells of the phenotype CD3+/HLA-DR+, as well as decrease in the percentage of CD45RA+/CD4+ and CD45RA+/CD8+ T cells, indicate greater numbers of activated T cells circulating in the blood of infected patients. Consistent parallel increases were seen also in the B lymphocyte subset which stained double-positive for CD19/CD5. There were no significant differences in the circulation of these chronic chagasic patients in the CD4:CD8 ratios. Also, no substantive phenotypic differences were observed in the lymphocyte populations between the two ends of the clinical spectrum (indeterminate versus cardiac) in chronic human Chagas' disease. These observations demonstrate that increased levels of activated T cells and CD5+ B cells are present in the circulation of people with chronic Chagas' disease. These are cell phenotypes that have been associated in other conditions with autoimmune, polyclonal, and hyperimmune responses. The specificities of these activated cells and the roles they may play in resistance or pathogenesis during chronic Chagas' disease need now to be determined.
TL;DR: This study evaluated production of interferon gamma in vitro by schistosome antigen-stimulated peripheral blood mononuclear cells from asymptomatic patients, and by PBMCs from apparently uninfected, untreated persons living in areas endemic for Schistosoma mansoni ('endemic normals').
Abstract: During human schistosomiasis host responses to antigens of various parasite life-cycle stages may contribute to whether the severe, hepatosplenic state develops or the patient remains relatively asymptomatic throughout infection, and may play a role in resistance. This study evaluated production of interferon gamma (IFN-gamma) in vitro by schistosome antigen-stimulated peripheral blood mononuclear cells (PBMCs) from asymptomatic patients, and by PBMCs from apparently uninfected, untreated persons living in areas endemic for Schistosoma mansoni ('endemic normals'). IFN-gamma production parallels PBMC proliferation in that schistosomal egg antigens stimulate patent patients' cells poorly, but strongly stimulate PBMCs from 'endemic normals'. This is proportionally true for antigens from adult worms and cercariae. Although asymptomatic patent patients' cells produced little or no IFN-gamma in response to the 3 schistosomal antigenic extracts, their PBMCs, and PBMCs from 'endemic normals', produced expected amounts of IFN-gamma when exposed to phytohaemagglutinin. This implies that persons with patent infections have schistosome antigen-specific defects in their ability to respond to IFN-gamma production that are not exhibited by putatively resistant 'endemic normals'.
TL;DR: In salt-loaded rats, increases in plasma angiotensin II levels in response to hemorrhage in normal rats were severely blunted, whereas ang Elliotensin plasma levels increased proportionately to the loss of blood volume.
TL;DR: It is demonstrated that TRMA is consistently associated with a state of thiamin deficiency, which is presumably secondary to reducedThiamin cellular transport and absorption, and to impaired intracellular pyrophosphorylation.
Abstract: Erythrocyte thiamin metabolism and transport were investigated in 7 patients from Brazil, Israel and Italy suffering from thiamin-responsive megaloblastic anaemia (TRMA) associated with diabetes mellitus and sensorineural deafness. All patients discontinued thiamin therapy for 4–7 days before the investigation. TRMA patients showed invariably reduced total thiamin levels in erythrocytes (percentage reduction compared with healthy controls, −46.8±3%; mean±SEM). The proportions of individual thiamin compounds, expressed as a percentage of total thiamin content, were within the normal range, whereas their absolute amounts were significantly decreased in the following order: thiamin monophosphate > thiamin pyrophosphate > thiamin. Thiamin pyrophosphokinase activity was also reduced as compared with controls (mean reduction±SEM, −25.9±1%). The saturable, specific component of thiamin uptake, which normally prevails at physiological concentrations of thiamin (<2µmol/L), was absent in erythrocytes obtained from TRMA patients, while the non-saturable (diffusive) component of uptake was normally present. These results confirm observations made previously in two patients and demonstrate that TRMA is consistently associated with a state of thiamin deficiency, which is presumably secondary to reduced thiamin cellular transport and absorption (caused by lack of a membrane-specific carrier), and to impaired intracellular pyrophosphorylation.
Journal Article•
TL;DR: The data presented here reinforce the hypothesis of the existence of complex site-specific interactions between multiple angiotensins and multiple receptors in the mediation of important central and peripheral effects of the RAS.
Abstract: 1. In this article we review the physiological actions of the heptapeptide angiotensin-(1-7) [Ang-(1-7)] at the periphery and on central pathways involved in the control of arterial pressure. Peripherally Ang-(1-7) has been shown to present a potent antidiuretic effect on water-loaded rats. Microinjection of pmol amounts of Ang-(1-7) into the dorsomedial or ventrolateral medulla (VLM) of anesthetized rats produces cardiovascular effects comparable to Ang II. In addition, in vitro experiments have shown that Ang-(1-7) has a potent vasopressin and prostaglandin releasing activity and excites neuronal activity in the hypothalamus and medulla. 2. Evidence for the existence of a new angiotensin receptor subtype that mediates the central cardiovascular actions of this active peptide of the renin-angiotensin system (RAS) is also provided. Neither the AT1 receptor antagonist DUP 753 or the AT2 receptor antagonist CGP 42112A blocked the pressor response produced by microinjection of Ang-(1-7) into the rostral VLM. However, the effect of Ang-(1-7) on VLM was completely abolished by the non-specific angiotensin receptor antagonist, Sar1-Thr8-Ang II. 3. The data presented here reinforce the hypothesis of the existence of complex site-specific interactions between multiple angiotensins and multiple receptors in the mediation of important central and peripheral effects of the RAS.
TL;DR: The results indicate that dipyrone reduced the hyperalgesia and edema in arthritic rats by a mechanism not involving release of prostaglandin-like substances, which supports the use of dipyr one as an alternative choice drug for the treatment of pain associated with arthritislike diseases in selected cases.
Abstract: Dipyrone, a pirazolone derivative, is a known analgesic drag with minor toxic effects associated with its administration. The aim of the present study was to determine the analgesic and antiinflammatory effects of dipyrone in a model of chronic inflammation (adjuvant-induced arthritis in rats). Hind-paw hyperalgesia was detected in arthritic rats from the 10th to the 16th day of observation. Edema development was maximum (twofold increase) at the 14th day of observation compared to control animals and reduced at the 16th day of observation. Dipyrone (1–50 mg/kg) dose-dependently reduced both hind-paw hyperalgesia and edema from arthritic rats. However, it was shown to be more potent as analgesic than antiinflammatory in the present model. In contrast, indomethacin (2 mg/kg) and dexamethasone (0.4 mg/kg) completely inhibited hind-paw hyperalgesia and edema development. Our results indicate that dipyrone reduced the hyperalgesia and edema in arthritic rats by a mechanism not involving release of prostaglandin-like substances. The possibility of dipyrone inducing analgesia in arthritic rats through a peripheral action supports the use of dipyrone as an alternative choice drug for the treatment of pain associated with arthritislike diseases in selected cases.
TL;DR: The patient showed evidence of cardiac dysfunction and damage, an increase in tracheobronchial aspirate/plasma protein concentration, light microscopic features of the lung compatible with the adult respiratory distress syndrome and electron microscopic findings compatible with acute lung injury and increased alveolocapillary membrane permeability.
TL;DR: The authors suggested that rhyme detection may be best described in terms of a sensitivity to some sort of global phonological similarity and that whether rhyme perception involves some level of analysis may, to a large extent, depend on the subject's reading level.
TL;DR: In this paper, the authors used LCAO (linear combination of atomic orbitals) calculations for the ground state of the Yukawa potential V(r) to obtain the best variational result so far.
Abstract: We perform LCAO (linear combination of atomic orbitals) calculations for the ground state of the Yukawa potential V(r)=-(${\mathit{e}}^{2}$/r)${\mathit{e}}^{\mathrm{\ensuremath{-}}\mathit{q}\mathit{r}}$ as a function of the screening parameter q. We obtain the best variational result so far for the ground-state energy ${\mathit{E}}_{0}$ as a function of q. We also obtain the critical exponents of both the probability density at the origin and the ground-state energy as functions of (q-${\mathit{q}}_{\mathit{c}}$), where ${\mathit{q}}_{\mathit{c}}$ is the critical q above which V(r) does not have a bound state. The use of the critical exponents permits the so far most precise determination of ${\mathit{q}}_{\mathit{c}}$, ${\mathit{q}}_{\mathit{c}}$=1.190 612 27\ifmmode\pm\else\textpm\fi{}0.000 000 04. We also show that it is possible to use the LCAO calculations as a tool to determine the analytical form of very precise variational wave functions. We obtain, in such a way, the wave function \ensuremath{\psi}=(${\mathit{e}}^{\mathrm{\ensuremath{-}}\mathit{a}\mathit{r}}$-${\mathit{e}}^{\mathrm{\ensuremath{-}}\mathit{b}\mathit{r}}$)/r+${\mathit{e}}^{\mathrm{\ensuremath{-}}\mathit{b}\mathit{r}}$/(r+\ensuremath{\alpha}). This variational wave function has a bound-unbound transition at ${\mathit{q}}_{\mathit{c}}$=1.190 610 74.
TL;DR: It is confirmed that street youths are at higher risk for HIV infection than their home-based peers and indicates a need for HIV prevention programs targeting this population.
TL;DR: In this article, two heptacoordinated organotin complexes, [MeSnCl(Hdaptsc)]Cl·MeOH (1) and [MeClCl2(H2dapsc)]- Cl2·2H2O (2), were obtained from MeSnCl3 and Me2SnCl2, respectively.
TL;DR: Os dados da declaracao de obito fornecem indicacao razoavel das principais causas de mortes infantis, principalmente quando se considera o grupamento diarreia-pneumonia-desnutricao, composto de patologias evitaveis e ainda de grande relevância como causa of mortalidade infantil na regiao.
Abstract: A partir de dados coletados para um estudo sobre a mortalidade infantil na regiao metropolitana de Belo Horizonte, MG, Brasil, foi selecionada uma amostra aleatoria de obitos infantis ocorridos em 1989, para avaliar a concordância da causa basica de morte registrada na declaracao de obito e a obtida apos revisao detalhada do prontuario hospitalar da crianca. Verificou-se que 11,7% dos obitos neonatais nao tiveram a causa basica registrada no atestado, confirmada pela investigacao nos prontuarios medicos (kappa = 0,61), o mesmo ocorrendo em 44,0% dos pos-neonatais (kappa = 0,47). Esta maior discordância no grupo pos-neonatal provavelmente se deveu a maior dificuldade de definicao das causas contribuintes e da causa basica dos obitos por diarreias, pneumonias e desnutricao, principais causas de mortalidade nesse grupo. Em relacao aos obitos por desnutricao e diarreia, observou-se associacao entre ambas em 76,9% das vezes em que a diarreia foi selecionada como causa basica, mostrando que essas patologias podem ser destacadas como um mesmo grupamento em saude publica. As discordâcias encontradas demonstram que os medicos ainda dao pouca importância ao seu papel como agentes geradores de informacao de saude. Os dados da declaracao de obito fornecem indicacao razoavel das principais causas de mortes infantis, principalmente quando se considera o grupamento diarreia-pneumonia-desnutricao, composto de patologias evitaveis e ainda de grande relevância como causa de mortalidade infantil na regiao.
TL;DR: Angiostrongylus vasorum infection was detected for the first time in eight foxes captured in the south of the State of Minas Gerais, Brazil and two crossbred dogs were successfully infected orally with larvae from the foxes' faeces.
Abstract: Angiostrongylus vasorum infection was detected for the first time in eight foxes (Dusicyon vetulus) captured in the south of the State of Minas Gerais, Brazil. Two crossbred dogs were successfully infected orally with larvae from the foxes' faeces.
TL;DR: BIC can be administered on an outpatient basis and seems to be effective in inducing tumor response and palliation in patients with disseminated squamous cell carcinoma of cervix, with a possible survival benefit for previously nonirradiated patients, with an acceptable toxicity profile.
Abstract: PURPOSEA bleomycin, carboplatin, and ifosfamide (BIC) chemotherapy protocol was designed to evaluate tumor response and palliation in patients with advanced cervical cancer.PATIENTS AND METHODSForty patients with stage IV primary or recurrent squamous cell carcinoma of the cervix (19 previously irradiated and 21 nonirradiated) were assigned to treatment with six cycles of BIC: bleomycin, 30 mg bolus on day 1; carboplatin, 200 mg/m2 bolus on day 1; and ifosfamide, 2g/m2 for 3 consecutive days, infused over 2 hours. Mesna was administered as a bolus 15 minutes, and 4 and 8 hours after ifosfamide at 20% (intravenous [IV]), and 40% (orally, at home) of the ifosfamide dose, respectively.RESULTSThirty-five patients (27 stage IVA and eight stage IVB) were considered eligible for response and toxicity evaluation. After a median of four cycles (maximum of six in responders), we observed objective responses in 21 patients (60%), with eight complete responses (CRs; 23%), including two histologically documented by la...
TL;DR: It is reported that Trypanosoma rangeli, a non-pathogenic parasite of man, contains two distinct classes of kDNA, minicircles called KP1 and KP2, which differ in size and molecular organization.
TL;DR: Variations in the morphology and contents of the CA may be related to different mechanisms of polyspermy blockade as well as to many of the groups studies.
Abstract: Depending on the species, the teleost cortical alveolus (CA) has from one to several layers of small to large cortical vesicles forming a continuous or discontinuous collar in the peripheral ooplasm. The histochemical composition of the CA, which also varies among species, is made of neutral glycoprotein, carboxylated glycocon‐jugate, neutral glycoprotein plus carboxylated glycoconjugate, sulfated glycoconjugate, neutral glycoprotein plus sialic acid‐rich glycoprotein. The CA was sudanophobic in all species analyzed. The morphology and contents of the CA seem to express common characters among many of the groups studies. Variations in the morphology and contents of the CA may be related to different mechanisms of polyspermy blockade.
TL;DR: In this paper, the reactivation of a Proterozoic age ductile shear zone along the northeastern extremity of the Transbrazilian lineament in northwest Ceara can be well documented by the intense deformation of an early Devonian sandstone body, about 30 km long and 4 km wide.
TL;DR: The diagnostic value of real-time sonography in the study of portal hypertension was assessed in 66 patients with hepatosplenic schistosomiasis mansoni, all with Symmers's fibrosis and esophageal varices and there was no statistical difference in the frequency of visualization of splanchnic vessels by sonography or splenoportography.
Abstract: Sessenta e seis pacientes com esquistossomose mansoni hepatoesplenica foram examinados pela ultra-sonografia do abdomen. Trinta e sete tambem submeteram-se a esplenoportografia. Todos apresentavam fibrose de Symmers e varizes de esofago. Selecionaram-se setenta e um individuos sem esquistossomose como controles. Mediu-se o diâmetro dos vasos porta nos pacientes e controles. A pressao intra-esplenica encontrava-se acima de 30 cm de agua em 44 de 60 pacientes com esquistossomose. Os limites superiores da normalidade para os vasos do sistema porta foram definidos como 12 mm para a veia porta, 9 mm para a veia esplenica no hilo e 9 mm para a veia mesenterica superior. O aumento do diâmetro da veia esplenica mostrou-se a alteracao mais sensivel para o diagnostico de hipertensao porta, seguido pelo aumento do diâmetro da veia porta. Observou-se correlacao direta entre o diâmetro da veia esplenica e da pressao intra-esplenica. Nao houve diferenca significativa na frequencia de visualizacao dos vasos esplâncnicos quando se usou a sonografia ou a esplenoportografia, exceto para as veias paraumbilical e mesenterica, mais frequentemente diagnosticadas pela ultra-sonografia.