Modelling Amazonian forest eddy covariance data: a comparison of big leaf versus sun/shade models for the C-14 tower at Manaus I. Canopy photosynthesis

In this study, we concentrate on modelling gross primary productivity using two simple approaches to simulate canopy photosynthesis: "big leaf" and "sun/shade" models. Two approaches for calibration are used: scaling up of canopy photosynthetic parameters from the leaf to the canopy level and fitting canopy biochemistry to eddy covariance fluxes. Validation of the models is achieved by using eddy covariance data from the LBA site C14. Comparing the performance of both models we conclude that numerically (in terms of goodness of fit) and qualitatively, (in terms of residual response to different environmental variables) sun/shade does a better job. Compared to the sun/shade model, the big leaf model shows a lower goodness of fit and fails to respond to variations in the diffuse fraction, also having skewed responses to temperature and VPD. The separate treatment of sun and shade leaves in combination with the separation of the incoming light into direct beam and diffuse make sun/shade a strong modelling tool that catches more of the observed variability in canopy fluxes as measured by eddy covariance. In conclusion, the sun/shade approach is a relatively simple and effective tool for modelling photosynthetic carbon uptake that could be easily included in many terrestrial carbon models.

Quimiossensibilidade durante exercício na insuficiência cardíaca: respostas ventilatórias, cronotrópicas e neurohormonais

FUNDAMENTO: Insuficiência cardíaca (IC) está associada com aumento da quimio-sensibilidade periférica e central em repouso, que pode estar correlacionada com um aumento na resposta ventilatória durante exercício. Entretanto, SUS sensibilidade na IC durante o exercício ainda não foi reportada. OBJETIVO: Testar se o estímulo dos quimiorreceptores centrais e periféricos em pacientes com IC pode modular respostas ventilatórias, cronotrópicas e neurohormonais durante exercício submáximo. MÉTODOS: Investigamos a quimio-sensibilidade central e periférica em 15 pacientes com insuficiência cardíaca (IC) e 7 controles normais (C), comparando a resposta durante 3 testes de caminhada de 6 minutos (TC6M), realizado em esteira ergométrica com: ar ambiente, em hipóxia e em hipercapnia (em ordem randômica). RESULTADOS: FR em ar ambiente nos grupos C e IC foi 17±2 e 22±2 (p<,0001); em hipóxia, foi 17±1 e 23±2 (p<,02); com CO25% foi 20±2 e 22±5 (p<,02). Volume tidal (VT) ou corrente em ar ambiente foi 1,25±0,17 e 1,08±0,19 (p<,01); em hipóxia 1,65±0,34 e 1,2±0,2(p<,0001); com CO25% 1,55±0,46 e 1,29±0,39 (p<,0001). Em repouso, o aumento na IC foi maior para VE (C 33±40%, IC 62±94%, p<,01), FC(C 7±10%, IC 10±10%, p<0,05) em repouso. Durante a hipóxia, o aumento durante o exercício na IC foi maior para FR (C 1±4, IC 11±6,p<,05), FC (C 12±2, IC 14±3, p<,05), VE/VO2 (C -4±18%, IC 24±21%, p<,01), FC/VO2 (C -26±11%, IC 11±5%, p<,01), VE/DC (C 36±10%, 46±14, p<,05% ) and FC/DC (C 18±8%, HF 29±11, p<,01). Durante exercício em hipóxia no grupo IC, o NO diminuiu e os níveis de IL-6 e aldosterona aumentaram. Os níveis neurohormonais permaneceram inalterados no grupo C. CONCLUSÃO: A quimio-sensibilidade central e a periférica durante o exercício estão aumentadas na IC e podem modular padrões respiratórios, cronotrópicos cardíacos e atividade neurohormonal durante exercício.

Biomphalaria aff. tenagophila do Sítio Arqueológico do Corondo, São Pedro da Aldeia, RJ

O presente estudo levou-nos a identificar as conchas de planorbídeos provenientes do Sítio Arqueológico do Corondó, RJ, como Biomphalaria aff. tenagophila. O Sítio foi datado entre 3.000 e 4.000 anos (C-14). A localização dos restos conquiliológicos sugere transporte por parte dos caçadores-coletores que ocuparam a área. Medidas comparativas feitas entre as B. aff. tenagophila antigas e B. tenagophila atuais de regiões próximas, demonstraram que as primeiras são mais largas do que as últimas.

Armazenamento de pitanga sob atmosfera modificada e refrigeração: I-transformações químicas em pós-colheita

Este experimento teve como objetivo avaliar as transformações pós-colheita em pitangas colhidas nos estádios de maturação vermelho-alaranjado (VA) e vermelho predominante (VP) e mantidas sob atmosfera modificada (AM) por filme de cloreto de polivinila (PVC), a 10 ± 0,5 ºC, 14 ± 0,5ºC e (90 ± 1%UR) e a temperatura ambiente (23 ± 2°C e 85 ± 2%UR). O uso de AM associada à refrigeração permitiu manutenção dos sólidos solúveis, acidez titulável, dos açúcares solúveis totais e vitamina C, e também resultou em menor taxa de aumento nos carotenóides totais para frutos do estádio de maturação VA mantido a 10 e 14ºC. Em conjunto, pitangas colhidas no estádio vermelho-alaranjado foram as que apresentaram melhor manutenção das características intrínsecas durante oito dias de armazenamento sob atmosfera modificada a 10ºC.

Comparative analysis of the trypanocidal activity and chemical properties of E-lychnophoric acid and its derivatives using theoretical calculations

E-Lychnophoric acid 1, its derivative ester 2 and alcohol 3 killed 100% of trypomastigote blood forms of Trypanosoma cruzi at the concentrations of 13.86, 5.68, and 6.48 µg/mL, respectively. Conformational distribution calculations (AM1) of 1, 2 and 3 gave minimum energies for the conformers a, b, c, and d, which differ from each other only in the cyclononene ring geometry. Calculations (DFT/BLYP/6-31G*) of geometry optimization and chemical properties were performed for conformers of 1, 2, and 3. The theoretical results were numerically compared to the trypanocidal activity. Calculated values of atomic charge, orbital population, and vibrational frequencies showed that the C-4-C-5 pi-endocyclic bond does not affect the trypanocidal activity of the studied compounds. Nevertheless, the structure of the group at C-4 strongly influences the activity. However, the theoretical results indicated that the intra-ring (C-1 and C-9) and pi-exocycle (C-8 and C-14) carbons of caryophyllene-type structures promote the trypanocidal activity of these compounds.

Anandamide injected into the lateral ventricle of the brain inhibits submandibular salivary secretion by attenuating parasympathetic neurotransmission

Our objective was to determine the effect of arachidonylethanolamide (anandamide, AEA) injected intracerebroventricularly (icv) into the lateral ventricle of the rat brain on submandibular gland (SMG) salivary secretion. Parasympathetic decentralization (PSD) produced by cutting the chorda tympani nerve strongly inhibited methacholine (MC)-induced salivary secretion while sympathetic denervation (SD) produced by removing the superior cervical ganglia reduced it slightly. Also, AEA (50 ng/5 µL, icv) significantly decreased MC-induced salivary secretion in intact rats (MC 1 µg/kg: control (C), 5.3 ± 0.6 vs AEA, 2.7 ± 0.6 mg; MC 3 µg/kg: C, 17.6 ± 1.0 vs AEA, 8.7 ± 0.9 mg; MC 10 µg/kg: C, 37.4 ± 1.2 vs AEA, 22.9 ± 2.6 mg). However, AEA did not alter the significantly reduced salivary secretion in rats with PSD, but decreased the slightly reduced salivary secretion in rats with SD (MC 1 µg/kg: C, 3.8 ± 0.8 vs AEA, 1.4 ± 0.6 mg; MC 3 µg/kg: C, 14.7 ± 2.4 vs AEA, 6.9 ± 1.2 mg; P < 0.05; MC 10 µg/kg: C, 39.5 ± 1.0 vs AEA, 22.3 ± 0.5 mg; P < 0.001). We showed that the inhibitory effect of AEA is mediated by cannabinoid type 1 CB1 receptors and involves GABAergic neurotransmission, since it was blocked by previous injection of the CB1 receptor antagonist AM251 (500 ng/5 µL, icv) or of the GABA A receptor antagonist, bicuculline (25 ng/5 µL, icv). Our results suggest that parasympathetic neurotransmission from the central nervous system to the SMG can be inhibited by endocannabinoid and GABAergic systems.

Efficiency of methods to detect Sclerotinia sclerotiorum in commercial soybean seed lots

Most soybean pathogens are seed transmitted, deserving emphasis the fungus Sclerotinia sclerotiorum, which has been presenting worrying levels of field incidence in some soybean cropping areas in several Brazilian states. The objective of this study was to verify the efficiency of different methods for detecting S. sclerotiorum on soybean seeds artificially infected in the laboratory and from field production areas with a historical disease incidence. Seed samples of seven different cultivars collected from naturally infested fields, and one seed sample artificially inoculated in the laboratory were used. The following detection methods recommended in the literature were compared: Blotter test at 7 ºC, 14 ºC, and 21 ºC; Rolled Paper; and Neon-S. Results demonstrated that these methods showed no repeatability and had a low sensitivity for detecting the pathogen in seeds from areas with disease incidence. They were effective, however, for its detection on artificially inoculated seeds. In the Blotter test method at 7 ºC, there was a lower incidence of other fungi considered undesirable during seed analysis.

Atividade antibacteriana do Aspergillus niger van Tieghem, 1867; pesquisas em 14 amostras da National Collection of Type Cultures (M. R. C.)

1. Pesquisamos a atividade antibacteriana em 14 amostras de Aspergillus niger da National Collection of Type Cultures. 2. Em meio de Raulin e Mosseray, sete amostras apresentaram atividade total, nunca superior a 1:10, contra Staphylococcus aureus nº 553, sendo que as amostras 1.161 e 2.390 permaneceram ativas por mais de 40 dias. 3. A utilização do meio de Czapek-Dox com 5% de "corn-steep" não melhorou os resultados obtidos com o meio de Raulin e Mosseray. 4. No meio de levedo peptonado, todas as amostras apresentaram-se inativas.

Soroprevalência de anticorpos antivírus da hepatite C em doadores de sangue, Brasil

OBJETIVOS: Determinar a soroprevalência de anticorpos antivírus da hepatite C (VHC) em doadores de sangue e correlacionar os resultados obtidos nos testes sorológicos de triagem e no teste confirmatório. MÉTODOS: Foram analisados os registros epidemiológicos e laboratoriais de 10.090 doadores de sangue do Hemonúcleo de Apucarana, Paraná, Brasil, do período de janeiro de 1997 a dezembro de 1999. Utilizou-se o método enzimaimunoensaio (ELISA) para detecção de anticorpos anti-VHC no soro. As amostras de soro com reatividade no ELISA foram avaliadas pelo teste confirmatório RIBA (recombinant immunoblot assay). Para análise estatística, utilizaram-se os testes qui-quadrado, teste exato de Fisher e índice de Kappa. RESULTADOS: Os resultados mostraram que 2.461 (24,4%) pessoas da amostra eram do sexo feminino e 7.629 (75,6%), do sexo masculino, com idade variando de 18 a 65 anos. Das 10.090 amostras de soro analisadas pelo ELISA, 88 apresentaram positividade, revelando soroprevalência de 0,9%, não demonstrando associação com as diferentes faixas etárias (p=0,197) e com o sexo (p=0,323). Avaliadas pelo teste confirmatório RIBA, 11 amostras (12,5%) apresentaram resultado positivo; 14 (15,9%), resultado indeterminado; e 38 (43,2%), resultado negativo. A análise estatística revelou alta concordância (índice Kappa de 0,939) entre os resultados obtidos no teste de ELISA e os obtidos no teste confirmatório. Amostras que forneceram resultado fracamente reagente no teste de ELISA apresentaram alta concordância com resultado negativo no RIBA immunoblot, e amostras que forneceram resultado fortemente reagente no teste de ELISA apresentaram alta concordância com o resultado positivo no RIBA. CONCLUSÕES: Os resultados reforçam a necessidade de confirmação de todos os resultados reagentes nos testes de triagem sorológica para pesquisa de anticorpo anti-VHC, uma vez que a confirmação da infecção pelo VHC é de extrema importância para o acompanhamento clínico, laboratorial e histológico dos doadores de sangue.

Hepatitis C virus seroprevalence and risk factors among patients with HIV infection

The objective of this study was to evaluate the prevalence and risk factors associated with HCV infection in a group of HIV seropositive patients. We analyzed the medical records of 1,457 patients. All patients were tested for HCV infection by third generation ELISA. Whenever possible, a sample of the positive patients was also tested for HCV by PCR. HCV positive patients were analyzed according to their risk factors for both infections. The prevalence of anti-HCV positive patients was 17.7% (258 patients). Eighty-two (82) of these patients were also tested by PCR and 81 were positive for HCV virus (98%). One hundred fifty-one (58.5%) were intravenous drug users (IDU); 42 (16.3%) were sexual partners of HIV patients; 23 (8.9%) were homosexual males; 12 (4.7%) had received blood transfusion; 61 (17.5%) had promiscuous sexual habits; 14 (5.4%) denied any risk factor; 12 (4.7%) were sexual partners of IDU. Two hundred four patients mentioned only one risk factor. Among them, 28 (10.9%) were sexual partners of HIV-positive patients. Although intravenous drug use was the most important risk factor for co-infection, sexual transmission seemed to contribute to the high HCV seroprevalence in this group of patients.

Patients with chronic hepatitis C and normal transaminases

Hepatitis C virus infection evolves progressively persisting in the majority of patients (85%). Most patients have high ALT (alanine aminotransferase) levels and approximately 25% normal ALT. The latter are usually female and there is no association between genotype and severity of hepatic lesion. Histologic analysis usually shows small lesion and absence or low amount of fibrosis, despite cirrhosis having been reported. Aiming at assessing prevalence, demographic, genotypical and anatomopathological characteristics in patients with normal ALT levels, we have carried out a study of 68 chronic hepatitis C patients between January 1997 and April 2000. There was a prevalence of 13.8% chronic hepatitis C patients with normal ALT levels, 45.6% of which were male and 54.4% female, the mean age being 38 +/- 13 years. We found a predominance of genotype 1 in 84.7% of the patients, genotype 2 in 6.8% and genotype 3 in 10.7%. In 52.9% of the cases liver biopsies revealed liver reaction, periportal activity score 0-1 was observed in 85.3% of the patients and score 2-4 was seen in 14.7%. Structural activity score 0-1 was seen in 73.5% of the patients and score 2-4 in 26.5% of them. Periportal activity > 2 and structural activity > 1 was seen in 29%, but steatosis was not seen in 73.5%. Our results suggest the need to revisit for liver biopsy practice in patients with Chronic Hepatitis C and normal transaminases.

Fatores associados às formas evolutivas graves da infecção crônica pelo vírus da hepatite C

Com o objetivo de descrever os fatores epidemiológicos e clínicos-laboratoriais e avaliar os fatores associados ao desenvolvimento de fibrose moderada e grave, realizou-se a revisão de 426 prontuários médicos de pacientes com infecção crônica pelo vírus da hepatite C, atendidos na Clínica de Moléstias Infecciosas e Parasitárias da Faculdade de Medicina da Universidade de São Paulo, no período de 01/01 a 31/12/2000. Dos pacientes incluídos no estudo, 56,3% eram do sexo masculino e 43,7% do sexo feminino. A idade deles variou de 18 a 69 anos. A hemotransfusão foi a forma mais freqüente de transmissão do vírus da hepatite C, encontrada em 128 (30%) dos casos e em 187 (43,9%) pacientes não foi encontrado nenhum fator de risco. A distribuição dos pacientes quanto à alteração arquitetural visto na biópsia hepática foi: grau 0 (14,1%), grau 1 (51,2%), grau 2 (20,6%), grau 3 (8%) e grau 4 (6,1%). Na análise multivariada, encontramos associação positiva entre intensidade da fibrose e idade maior que 40 anos na data da biópsia hepática, níveis séricos de albumina abaixo do limite inferior normal, gama-glutamiltransferase maior ou igual a duas vezes o limite superior da normalidade, plaquetas em número menor que 150.000/mm³ e alta atividade necro-inflamatória. Os dados foram inconclusivos para testar a associação entre gravidade da fibrose e alcoolismo.

Epidemiological profile of hepatitis C in blood donors at the Uberaba Regional Blood Center

The aim of the present study was to outline the serological profile of hepatitis C among blood donors seen at the Uberaba Regional Blood Center, Hemominas Foundation, over the last 14 years. The frequency of hepatitis C was compared between first-time and repeat donors and the epidemiological characteristics of those with positive and indeterminate ELISA anti-HCV (third and fourth generation) were analyzed based on the donor histories kept in the archives of the Uberaba Regional Blood Center. The serological ineligibility rate was 0.3%, with higher prevalence in the group of first-time donors. We did not find any significant differences regarding age, skin color, marital status or place of residence between eligible and ineligible donors; however, the frequency of positive serology was higher among men. The lower (0.3%) rate of ineligibility due to hepatitis C that was observed at the Uberaba Regional Blood Center, in relation to most Brazilian blood centers, is probably due to the large number of repeat donors (83.3%). This reinforces the importance of achieving donor commitment for increasing transfusion safety.

Hepatitis C: sexual or intrafamilial transmission? Epidemiological and phylogenetic analysis of hepatitis C virus in 24 infected couples

The role of sexual or intrafamilial transmission of hepatitis C is controversial. A phylogenetic analysis was performed on the non-structural region 5B of the hepatitis C virus (NS5B-HCV). High percentages of homology (mean of 98.3%) were shown between the couples. Twenty (83.3%) of the 24 men but only two of the women (8.3%) reported having had sexually transmitted diseases during their lives. The risk factors for HCV acquisition were blood transfusion (10 couples), use of illegal injected drugs (17), use of inhalants (15), acupuncture (5) and tattoos (5). The shared use of personal hygiene items included toothbrushes between six couples (25%), razor blades between 16 (66.7%), nail clippers between 21 (87.5%) and manicure pliers between 14 (58.3%). The high degree of similarity of the hepatitis C virus genome supports the hypothesis of hepatitis C virus transmission between these couples. The shared use of personal hygiene items suggests the possibility of intrafamilial transmission of infection.

Indeterminate RIBA results were associated with the absence of hepatitis C virus RNA (HCV-RNA) in blood donors

Introduction: Hepatitis C virus (HCV) infection is diagnosed by the presence of antibodies and is supplemented by confirmatory testing methods, such as recombinant immunoblot assay (RIBA) and HCV-RNA detection. This study aimed to evaluate the efficacy of RIBA testing to diagnose HCV infection in blood donors positive for anti-HCV antibodies. Methods: A total of 102 subjects positive for anti-HCV determined by enzyme-linked immunosorbent assay (ELISA) at the Hematology and Hemotherapy Foundation of Bahia (HEMOBA) were later assessed with new samples using the Abbott Architect anti-HCV test (Abbott Diagnostics, Wiesbaden, Germany), the RIBA III test (Chiron RIBA HCV 3.0 SIA, Chiron Corp., Emeryville, CA, USA), the polymerase chain reaction (PCR; COBAS® AMPLICOR HCV Roche Diagnostics Corp., Indianapolis, IN, USA) and line probe assay (LiPA - Siemens, Tarrytown, NY, USA) genotyping for HCV diagnosis. Results: Of these new samples, 38.2% (39/102) were positive, 57.8% (59/102) were negative and 3.9% (4/102) were indeterminate for anti-HCV; HCV-RNA was detected in 22.5% (23/102) of the samples. RIBA results were positive in 58.1% (25/43), negative in 9.3% (4/43) and indeterminate in 32.6% (14/43) of the samples. The prevailing genotypes were 1 (78.3%, 18/23), 3 (17.4%, 4/23) and 2 (4.3%, 1/23). All 14 samples with indeterminate RIBA results had undetectable viral loads (detection limit ≤50 IU/mL). Of these samples, 71.4% (10/14) were reevaluated six months later. Eighty percent (8/10) of these samples remained indeterminate by RIBA, and 20% (2/10) were negative. Conclusions: In this study, individuals with indeterminate RIBA results had no detectable HCV-RNA.