Universidade Federal De Minas Gerais Research Articles

Bistability double-crossing curve effect in a polariton-laser semiconductor microcavity

Departamento de Fisica, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil(Dated: February 1, 2008)We report an experimental observation of polaritonic optical bistability of the laser emission ina planar semiconductor microcavity with a 100˚A GaAs single quantum well in the strong-couplingregime. The bistability curves show crossings that indicate a competition between a Kerr-like effectinduced by the polariton population and thermal effects. Associated with the bistability, laser-likeemission occurs at the bare cavity mode.

Characterization of Heme as Activator of Toll-like Receptor 4

Heme is an ancient and ubiquitous molecule present in organisms of all kingdoms, composed of an atom of iron linked to four ligand groups of porphyrin. A high amount of free heme, a potential amplifier of the inflammatory response, is a characteristic feature of diseases with increased hemolysis or extensive cell damage. Here we demonstrate that heme, but not its analogs/precursors, induced tumor necrosis factor-alpha (TNF-alpha) secretion by macrophages dependently on MyD88, TLR4, and CD14. The activation of TLR4 by heme is exquisitely strict, requiring its coordinated iron and the vinyl groups of the porphyrin ring. Signaling of heme through TLR4 depended on an interaction distinct from the one established between TLR4 and lipopolysaccharide (LPS) since anti-TLR4/MD2 antibody or a lipid A antagonist inhibited LPS-induced TNF-alpha secretion but not heme activity. Conversely, protoporphyrin IX antagonized heme without affecting LPS-induced activation. Moreover, heme induced TNF-alpha and keratinocyte chemokine but was ineffective to induce interleukin-6, interleukin-12, and interferon-inducible protein-10 secretion or co-stimulatory molecule expression. These findings support the concept that the broad ligand specificity of TLR4 and the different activation profiles might in part reside in its ability to recognize different ligands in different binding sites. Finally, heme induced oxidative burst, neutrophil recruitment, and heme oxygenase-1 expression independently of TLR4. Thus, our results presented here reveal a previous unrecognized role of heme as an extracellular signaling molecule that affects the innate immune response through a receptor-mediated mechanism.

Outcomes of radiofrequency in advanced keratoconus

To evaluate the use of radiofrequency energy to correct advanced keratoconus. Universidade Federal de Minas Gerais, Belo Horizonte, and Universidade de Ciências da Saúde de Alagoas, Maceió, Brazil. In this prospective comparative study, radiofrequency was applied to 25 eyes of 21 consecutive patients. One group comprised patients with a K-reading between 54.0 diopters (D) and 58.0 D; 8 thermal spots were placed at the 4.0 mm optical zone. The other group comprised patients with a K-reading greater than 58.0 D; 16 spots were applied at the 4.0 mm and 5.0 mm optical zones. The minimum follow-up was 18 months in all patients. Differences between preoperative and postoperative uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), manifest refraction, and K-readings were clinically and statistically evaluated. At end of the 18-month follow-up, the mean BSCVA in the 8-spot group improved from 20/100 (0.71+/-0.25 logMAR) preoperatively to 20/40 (0.32+/-0.11 logMAR) and in the 16-spot group, from 20/200 (1.03+/-0.30 logMAR) to 20/60 (0.62+/-0.22 logMAR). The mean manifest refractive spherical equivalent (MRSE) improved from -7.70 D+/-5.20 (SD) preoperatively to -6.82+/-4.41 D after 18 months in the 8-spot group and from -11.33+/-6.70 to -8.38+/-5.12 D, respectively, in the 16-spot group. The mean best contact lens-corrected visual acuity was 20/30 (0.18+/-0.24 logMAR) in the 8-spot group and 20/40 (0.31+/-0.19 logMAR) in the 16-spot group. A dense corneal scar was seen in 1 patient in the 16-spot group at the 6-month follow-up. Radiofrequency appeared safe for the treatment of advanced keratoconus. Contact lens fitting was stable in all cases.

A calorimetry system for metabolism trials

An indirect calorimetry system for rapid determination of CO2 and CH4 production and O2 consumption to estimate heat production of animals was built at Escola de Veterinária da Universidade Federal de Minas Gerais, Brazil. Procedures for determination of correction and calibration factors for gas analyzers and the whole system, using standard test gases were described. In addition, a metabolic trial was performed to evaluate heat production of lambs fed ad libitum. It is concluded that the system is suitable for heat production determinations in small and medium size animals.

Saturação por bases no crescimento inicial e na produção de flavonóides totais da fava-d'anta

Com o objetivo de estudar o efeito da calagem, mediante a elevação da saturação por bases, sobre o crescimento e a produção de flavonóides totais de fava-d'anta cultivada em um solo de Cerrado de Minas Gerais, foi conduzido um experimento no Instituto de Ciências Agrárias da Universidade Federal de Minas Gerais, no período de outubro/2003 a fevereiro/2004. O delineamento experimental utilizado foi inteiramente casualizado, sendo cinco valores de saturação por bases: 10 (saturação natural), 25; 40; 55 e 70%, com seis repetições. Os resultados obtidos mostraram que o aumento da saturação por bases diminuiu o crescimento e não influenciou o teor de flavonóides totais da fava-d'anta.

Histiocitose das células de Langerhans: experiência de 16 anos

OBJETIVOS: Descrever a apresentação clínica da histiocitose das células de Langerhans e comparar sua evolução de acordo com a idade, estadiamento e resposta ao tratamento. MÉTODOS: Análise retrospectiva dos dados referentes a 33 crianças com histiocitose das células de Langerhans acompanhadas no Hospital das Clínicas da Universidade Federal de Minas Gerais no período de 1988 a 2004. RESULTADOS: A idade ao diagnóstico variou de 2 meses a 16 anos (mediana: 2,5 anos). Dezessete crianças eram do sexo masculino. O tempo de seguimento variou de 21 dias a 16,2 anos (mediana: 3,4 anos). As manifestações clínicas mais comuns ao diagnóstico foram lesões osteolíticas, linfadenomegalia e lesões cutâneas. A sobrevida global para todo o grupo foi de 86,1% aos 16 anos (IC95% 66,6-94,6). Os óbitos ocorreram em pacientes com doença multissistêmica e disfunção orgânica ao diagnóstico. Os pacientes que apresentaram resposta "melhor" à sexta semana de tratamento apresentaram uma probabilidade estimada de sobrevida global significativamente maior em relação aos que apresentaram progressão da doença. A sobrevida global foi significativamente maior para os pacientes com doença em um único sistema. A probabilidade de sobrevida livre de eventos para todo o grupo foi de 30,9% aos 16 anos (IC95% 15,6-47,5), sendo significativamente maior para os portadores de doença em um único sistema. A idade não se associou com a sobrevida livre de eventos. A seqüela mais comum foi o diabetes insipidus. Não foram observados casos de neoplasias secundárias. CONCLUSÃO: A histiocitose das células de Langerhans apresenta uma grande variedade de manifestações clínicas, com alta taxa de recidivas e baixa taxa de mortalidade.

Langerhans cell histiocytosis: a 16-year experience

To describe the clinical course of Langerhans cell histiocytosis and to compare its outcome according to age, staging of the disease and treatment response. Retrospective analysis of data on 33 children with Langerhans cell histiocytosis followed at Hospital das Clínicas, Universidade Federal de Minas Gerais, Brazil, between 1988 and 2004. Age at diagnosis ranged from 2 months to 16 years (median: 2.5 years). Seventeen children were male. The follow-up period varied from 21 days to 16.2 years (median: 3.4 years). The most common clinical manifestations at diagnosis were osteolytic lesions, enlarged lymph nodes and skin lesions. The overall survival rate for the whole group was 86.1% at 16 years (95%CI 66.6-94.6%). Deaths occurred in patients with multisystem disease and organ dysfunction at diagnosis. Those patients who had a "better" response to treatment in the sixth week were likely to have a significantly higher overall survival rate than those who showed disease progression. Overall survival rate was significantly higher for patients with single-system disease. The disease-free survival rate for the whole group was 30.9% at 16 years (95%CI 15.6-47.5%), and was significantly higher for those with single-system disease. Age groups were not associated with different disease-free survival rates. Diabetes insipidus was the most common sequela. No cases of secondary neoplasms were observed. The clinical manifestations of Langerhans cell histiocytosis vary widely, with a high relapse rate and low mortality rate.

Evaluation of atopy among mouth-breathing pediatric patients referred for treatment to a tertiary care center

A mouth breather is someone who uses his/her oral cavity as the main airway during breathing. This is a syndrome with several etiologies, but allergic rhinitis plays a key role due to its high prevalence. The aim of this study was to assess the presence of atopy among mouth-breathing patients referred to a tertiary care center in the metropolitan region of Belo Horizonte, Brazil. Cross-sectional, descriptive study carried out at Hospital das Clínicas of Universidade Federal de Minas Gerais. Patients aged 2 to 12 years, admitted between November 2002 and April 2004, were included. Parents or surrogates completed a comprehensive questionnaire, and patients were submitted to a skin test for inhalant allergens. A total of 140 patients participated in the study. Those with a positive result for at least one allergen were regarded as atopic. The statistical analyses were made using SPSS, with univariate analyses followed by logistic regression. Of 140 patients, 44.3% (62/140) obtained positive results on the allergic test. Mites were the most predominant allergens, with a positive rate of 100% among atopic patients. In the multivariate analysis, atopy was significantly associated with the male sex (p = 0.05), presence of asthma (p = 0.014), lower number of people sleeping in the same room with the patient (p = 0.005), absence of passive smoking (p = 0.005) and absence of sleep apnea (p = 0.003). The high prevalence of positive results on the allergic test highlights the importance of allergologic investigation in mouth-breathers, since allergy has specific treatments that may reduce morbidity in these patients when properly used.

Avaliação de atopia em crianças respiradoras bucais atendidas em centro de referência

OBJETIVO: Respirador bucal é o indivíduo que utiliza a cavidade oral como principal via aérea durante a respiração. Trata-se de síndrome de múltiplas etiologias, dentre as quais a rinite alérgica merece destaque por sua alta prevalência. Este trabalho teve como objetivo avaliar a presença de atopia entre respiradores bucais encaminhados a serviço de referência da região metropolitana de Belo Horizonte. MÉTODOS: Estudo transversal e descritivo, realizado no Hospital das Clínicas da Universidade Federal de Minas Gerais. Foram incluídos pacientes de 2 a 12 anos de idade, com período de admissão entre novembro de 2002 e abril de 2004. Os responsáveis responderam a um questionário completo, e os pacientes foram submetidos a teste alérgico cutâneo para inalantes. Houve 140 participantes do estudo. Foram classificados como atópicos aqueles que apresentaram teste positivo para, no mínimo, um alérgeno. As análises estatísticas foram feitas no programa SPSS, usando análises univariadas seguidas pela regressão logística. RESULTADOS: Entre os 140 pacientes, 44,3% (62/140) tiveram teste alérgico positivo. Ácaros foram os alérgenos predominantes, apresentando positividade em 100% dos atópicos. Em análise multivariada, atopia esteve significativamente associada ao sexo masculino (p = 0,05), presença de asma (p = 0,014), menor número de pessoas dormindo no mesmo cômodo que o paciente (p = 0,005), ausência de tabagismo passivo (p = 0,005) e ausência de apnéia noturna (p = 0,003). CONCLUSÃO: A alta prevalência de positividade no teste alérgico enfatiza a importância da investigação alergológica em respiradores bucais, pois a alergia tem formas específicas de tratamento que podem reduzir a morbidade desses pacientes quando adequadamente utilizadas.

Perfil das gestantes infectadas pelo HIV atendidas em pré-natal de alto risco de referência de Belo Horizonte

OBJETIVOS: identificar gestantes infectadas pelo HIV em centro de referência e investigar características refe-rentes à infecção e paridade. MÉTODOS: estudo transversal, que abrangeu toda a população de gestantes infectadas pelo HIV assistidas no Pré-Natal de Alto Risco do Hospital das Clínicas da Universidade Federal de Minas Gerais, em 2004. Foram coletados dados demográficos, epidemiologia da infecção pelo HIV e história obstétrica. Para análise estatística foi utilizado o SPSS 12.0. RESULTADOS: foram identificadas 85 mulheres com média de idade de 29,1 anos e 90 gestações. Em 55 gestações (61,1%), as mulheres tinham conhecimento prévio da infecção. Sessenta e quatro (71,1%) informavam união estável. Provavelmente, todas adquiriram o HIV em relações heterossexuais. Cinqüenta e quatro (60%) tiveram o diagnóstico durante alguma gravidez. A média global de gestações foi 3,5, sendo 1,71 após o diagnóstico. Pacientes com diagnóstico prévio apresentaram maior média de gestações, em relação àquelas com diagnóstico na gestação estudada (p = 0,002). Oitenta e seis gestantes usaram anti-retroviral, sendo 56,7% por indicação terapêutica. Não foram verificados casos de transmissão vertical. CONCLUSÕES: novas gestações em mulheres infectadas pelo HIV não são raras, apesar dos recursos de contracepção oferecidos. Assim, outras investigações são necessárias para a identificar suas dificuldades não abordadas durante a assistência médica de rotina.

Effectiveness of dual and triple antiretroviral therapy in the treatment of HIV-infected children

The use of antiretroviral therapy in HIV-infected children has been a widely discussed issue. The aim of this study was to compare the effectiveness of dual nucleoside analogue reverse transcriptase inhibitor (NRTI) regimens and three-drug regimens [2NRTI+ non-nucleoside reverse transcriptase inhibitor (NNRTI) or protease inhibitor (PI)] in a cohort of HIV-infected children. The study was carried out in a referral center for the management of infected children, which is affiliated with the School of Medicine of Universidade Federal de Minas Gerais (UFMG). Those children whose antiretroviral therapy was implemented between January 1998 and December 2000 and who were followed until December 2001 were included in the study. Therapeutic failure or death was regarded as the endpoint in our analysis. A total of 101 patients were assessed, 58 (57.4%) on dual therapy and 43 (42.6%) on triple therapy. No statistically significant difference was observed between the groups in terms of gender, age, CD4+ count and baseline viral load. The average duration of dual therapy was 26.3 months (95%CI 21.3-31.3) and that of triple therapy was 34.3 months (95%CI 29.2-39.5%). There was therapeutic failure in 33 (56.9%) patients on dual therapy and in 11 (25.6%) patients on triple therapy (log rank = 5.03; p = 0.025). The relative risk of therapeutic failure of the dual therapy was 2.2 times higher (95%CI 1.3-3.9). The percentage of initial CD4+ T cells was a predictor of risk for therapeutic failure (p = 0.001). Patients on triple therapy showed a more remarkable reduction in their viral load (p = 0.001). Triple therapy was efficient for a longer time period and showed better virologic response than dual therapy in this cohort of HIV-infected children. Therefore, triple therapy should be the treatment of choice.

Computer-Based Conformational Analysis of Acetylcholine and Muscarine Combined with an Overview of the Receptor-Ligand Interaction

Drug development is among the topics studied in the pharmaceutical chemistry course for pharmacy undergraduates of Universidade Federal de Minas Gerais, Brazil. Computational advances in the last 20 years together with the availability of user-friendly software have promoted the development of simple computer-assisted molecular-modeling experiments for bioactive molecules. The knowledge of the specific stereochemistry of active sites for enzymes and some receptor sites justifies the study of drug conformations capable of interacting with these sites. Only a single conformation from the many possible conformations of a flexible molecule can bind to the receptor site. We report a procedure to perform conformational analysis using the systematic search method and the superimposition of two bioactive molecules, acetylcholine and muscarine. The undergraduate students individually perform the proposed procedure using a personal computer.

The retention of Cryptosporidium sp. oocysts at varying depths in slow sand filters: A pilot study

Research Article| May 01 2006 The retention of Cryptosporidium sp. oocysts at varying depths in slow sand filters: A pilot study Léo Heller; Léo Heller 1Department of Sanitary and Environmental Engineering, School of Engineering, Universidade Federal de Minas Gerais, Brazil, Av. Contorno, 842/701 – 30.110-060,Belo Horizonte, Brazil, Tel.: 0055-31-3238-1958, Fax: 0055-31-3238-1879; E-mail: heller@desa.ufmg.br Search for other works by this author on: This Site PubMed Google Scholar Ludmila Ladeira Alves de Brito Ludmila Ladeira Alves de Brito 2IBAMA, Brazilian Institute of the Environment and Renewable Natural Resources, Ministry of the Environment, Brazil Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2006) 55 (3): 193–206. https://doi.org/10.2166/aqua.2006.0005 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Twitter LinkedIn Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Léo Heller, Ludmila Ladeira Alves de Brito; The retention of Cryptosporidium sp. oocysts at varying depths in slow sand filters: A pilot study. Journal of Water Supply: Research and Technology-Aqua 1 May 2006; 55 (3): 193–206. doi: https://doi.org/10.2166/aqua.2006.0005 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex The retention of protozoa cysts and oocysts at varying depths in slow sand filters is a subject still not completely understood. A better understanding may contribute to an improved assessment of the risk of infections in those populations that receive water treated by slow sand filtration and could also contribute to the improvement of the planning and design of slow sand filters. With these aims, this paper intends to communicate advances in the understanding of the retention of Cryptosporidium oocysts and microbiological indicators of water quality in the filter media. In the study, Cryptosporidium oocysts presented a similar behaviour for the higher filtration rate (6 m3 m−2 ·d) in both flows investigated. For lower filtration rates (3 m3 m−2 ·d), the penetration of these oocysts is higher in the downflow filter. In the upflow filter the retention is limited to the initial 0.45 m of the filter media. There was no accumulation of oocysts inside the filter media as the run progressed, suggesting the existence of some control mechanism. The schmutzdecke seems to play an effective role in the removal of protozoa only when it is well developed. A weak relationship was found between the Cryptosporidium oocysts and both water quality and treatment efficiency indicators. Cryptosporidium, microbiological indicators, schmutzdecke, slow sand filtration, turbidity This content is only available as a PDF. © IWA Publishing 2006 You do not currently have access to this content.

A new species of the spider genus Aculepeira Chamberlin & Ivie (Araneae: Araneidae) found in nests of Trypoxylon (Trypargilum) lactitarse Saussure (Hymenoptera: Sphecidae) from Minas Gerais, Brazil.

Aculepeira angeloi sp. n. is described based on specimens found in nests of Trypoxylon (Trypargilum) lactitarse Saussure from the Ecological Station of the Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.

Odontogenic tumors: a study of 340 cases in a Brazilian population

The aim of this study was to determinate the relative frequency of odontogenic tumors (OTs) in a Brazilian population and to compare this data with previous reports. We reviewed the achieves of 19 123 specimens from oral pathology laboratory of Universidade Federal de Minas Gerais, from 1954 to 2004. Using the criteria of histologic typification published by the World Health Organization in 1992, we classified the OTs. A total of 340 OTs were found. The frequency of OTs comprises 1.78% of all pathologic specimens in our laboratory. The most frequent tumor was ameloblastoma (45.2%), followed by odontomas (24.91%), and myxomas (9.1%). Odontogenic tumors are uncommon lesions in this Brazilian population and malignant OTs are very rare. The relative frequency of various types of OTs, age, and gender distribution are similar to those reported in African, Asian but not to Chilean and North American series.

Testagem inicial e capacidade discriminatória da escala "UFMG Syedenha's Chorea Rating Scale (USCRS)"

Recently we developed and validated the Universidade Federal de Minas Gerais (UFMG) Sydenham's chorea Rating Scale (USCRS) to systematically assess SC patients. In this study, we assessed 97 children and adults with SC (mean age +/- SD, 15.5 +/- 5.9; male/female, 31/66) seen at the Movement Disorders Clinic at UFMG employing the USCRS. The patients were divided into 4 groups according to their clinical status: acute (n=19), recurrent (n=17), persistent (n=19) and remission (n=42). The mean +/- SEM USCRS scores for each group were: 47.7 +/- 4.7 for acute group, 29.5 +/- 2.6 for recurrent group, 17.6 +/- 3.1 for persistent group and 1.1 +/- 0.2 for remission group. All pair comparisons were statistically significant (p<0.05). Our results indicate that the USRSC can reasonably discriminate groups of SC patients in different clinical stages of the disease.

Cornifolin, a new bis-tetrahydrofuran Annonaceous acetogenin from Annona cornifolia

Seeds of Annona cornifolia A. St.eHil. were collected in Curvelo region, Minas Gerais State, from June to August 1998. The species was identified by M. C. R. Mello-Silva and a voucher specimen (BHCB 68114) deposited at the Instituto de Ciencias Biologicas Herbarium, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. We report here the isolation and structure elucidation of one novel C-37 adjacent bis-tetrahydrofuran acetogenin, named cornifolin (1) from the ethanolic extract. The structure and relative stereochemistry of the acetogenin were elucidated based on 1D

What are helicobacter doing in the hepatobiliary system?

What are helicobacter doing in the hepatobiliary system?

What are helicobacter doing in the hepatobiliary system?

What are helicobacter doing in the hepatobiliary system?

Hepatite auto-imune tipo 1 em crianças e adolescentes: avaliação da suspensão do tratamento imunossupressor

To assess treatment withdrawal in children and adolescents with autoimmune hepatitis, with clinical and laboratory remission for a minimum period of 24 months, determining the relapse rate after treatment withdrawal. This is a descriptive, retrospective and partially prospective study of 21 children and adolescents with type 1 autoimmune hepatitis treated at the Outpatient Division of Pediatric Hepatology, Teaching Hospital of Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil, between January 1986 and December 2001. We assessed 54 patients and selected 21, of whom 19 were female subjects (90.5%), aged between 5.7 and 17.6 years (median = 13.8 years), with a mean follow-up of 5.1+/-2.4 years (median = 4.4 years) and an average clinical and laboratory remission of 4.1+/-1.5 years (median = 4.1 years). Out of the 21 patients studied, 10 (47.6%) manifested some inflammatory activity that prevented the discontinuation of treatment, which was withdrawn in 11 patients (52.4%). Out of these, six patients (54.5%) presented reactivation of the disease and five maintained clinical and laboratory remission with a mean follow-up of 4+/-1 years (median = 3.9 years). The time interval between discontinuation of treatment and reactivation of the disease ranged from 29 days to 40.3 months (median = 2.2 months). We observed a high relapse rate (54.5%) in this group of patients with autoimmune hepatitis, which was more frequent within the first 12 months after treatment withdrawal, in addition to a high number of patients that presented some degree of inflammatory activity despite the long period of clinical and laboratory remission.