Determinação da 2,5-hexanodiona em amostras de urina submetidas à hidrólise ácida: importância da coluna cromatográfica e do pH do meio

Acidic hydrolysis of samples is frequent in urinary 2,5-hexanodione determination. This hydrolysis should be performed under proper conditions, in order to avoid interference, such as the presence of 2,5-dimethylfurane and 2-acetylfurane. The results of the present work, as well as data from the literature, show that the use of non-polar or slightly polar chromatographic columns of 30 m length is an essential condition for 2,5-HD determination in an acid hydrolysed urine sample. In the same way the pH should be kept between 0.3 and 0.5. The mean concentrations of 2,5-HD in samples submitted to hydrolysis (0.50 ± 0.28 mg/g of creatinine) was about 3 times higher than those found in the samples without acid hydrolysis (0.19 ± 0.3 mg/g of creatinine).

Urinary 2,5-hexanedione in workers exposed to n-hexane: influence of the sample treatment

The aim of the present study was to determine 2,5-hexanedione (2,5-HD), a metabolite of n-hexane, by gas chromatography/flame ionization detection in 31 workers exposed to n-hexane after two types of sample pretreatment, i.e., with (total 2,5-HD) and without (free 2,5-HD) acid hydrolysis. The mean urinary 2,5-HD was 0.52 mg/L (free) and 2.88 mg/L (total), this difference being significant (Student t-test, p < 0.05). The differences in the results according to the sample treatment support the need to modify the current Brazilian legislation, which proposes the analysis of 2,5-HD without indicating whether it is the free or total metabolite.

Importância das variáveis altura dominante e altura total em equaçõea hipsométricas e volumétricas

Este estudo foi conduzido, visando avaliar as seguintes hipóteses: a) equações hipsométricas devem ser obtidas por parcela, apenas em função do dap; e b) equações volumétricas devem ser locais, em função apenas do dap. Foram utilizados dados de quatro parcelas distribuídas ao acaso em um povoamento de eucalipto de 67,81 ha e de 50 parcelas distribuídas ao acaso em um povoamento de 121,3 ha, da mesma espécie. Em uma análise inicial, a fim de obter valores reais de altura total e de volume sólido, realizou-se uma cubagem rigorosa de todas as árvores das quatro parcelas. Foram utilizados, ainda, dados de 277 árvores cubadas rigorosamente nos povoamentos. Para avaliar a exatidão das estimativas e as hipóteses formuladas, empregou-se o procedimento estatístico proposto por Leite & Oliveira (2002). Com base nos resultados, as hipóteses a e b foram rejeitadas a 1% de probabilidade. Concluiu-se, portanto, que em um inventário florestal a variável Hd deve ser considerada e que as equações volumétricas devem ser regionais.

Uso de traçadores para avaliação da hidrodinâmica de sistemas alagados construídos operando sob condições climáticas tropicais

Sistemas alagados construídos (SACs) são, atualmente, importante opção para o tratamento de resíduos e controle da poluição pontual e difusa. O uso de SACs tem aumentado ano a ano, entretanto o nível de entendimento da hidrodinâmica do processo não tem crescido na mesma proporção. Traçadores fluorescentes apresentam-se como opção na determinação de curvas de distribuição de tempos de residência (DTR) e de parâmetros hidrodinâmicos, como número de dispersão e eficiência hidráulica. A pesquisa foi realizada com o objetivo de avaliar dois corantes (rodamina WT e fluoresceína sódica) na determinação das características hidrodinâmicas de SACs com escoamento subsuperficial, operando em região de clima tropical. Os tempos de residência experimentais (τR) para os SACs variaram entre 4,5 e 5,0 dias, e os parâmetros de modelos teóricos foram obtidos para cada sistema, indicando dispersões muito pequenas. Os SACs, que apresentavam relação comprimento/largura (L/B) de 24/1, comportaram-se como sistemas de escoamento próximo ao pistonado. Embora a massa total adicionada não tenha sido recuperada (a adsorção é um dos mecanismos de perda), a pesquisa indicou que a rodamina WT pode ser utilizada com resultados satisfatórios na avaliação do comportamento hidrodinâmico de SACs.

Utilização de lisímetros de pesagem para a determinação dos coeficientes de cultura do meloeiro (Cucumis melo L.) para cultivo em estufa agrícola na região de Araras - SP

Esta pesquisa foi conduzida em uma estufa agrícola instalada na área experimental do Centro de Ciências Agrárias da Universidade Federal de São Carlos, localizado em Araras - SP. O solo da área experimental é um Latossolo Vermelho-Escuro, distrófico, de horizonte A moderado e textura argilosa. Os meloeiros estudados foram os híbridos Louis e HD 90. O experimento foi irrigado por gotejamento, e o controle da irrigação, realizado por meio de dois lisímetros de pesagem instalados dentro da estufa. A umidade do solo foi monitorada com uma sonda de TDR e mantida próxima de sua capacidade de campo. As informações climatológicas relevantes ao projeto foram coletadas em estações meteorológicas automáticas, instaladas dentro e fora da estufa. A evapotranspiração de referência (ETo) foi estimada pelos modelos agroclimáticos de Penman-Monteith, Penman, Makkink e do Tanque Classe A. Os consumos totais de água medidos nos lisímetros foram de 254,5 mm e 188,6 mm, respectivamente, para os meloeiros Louis e HD 90, os quais correspondem ao consumo médio diário de 3,18 mm e 2,35 mm. Todos os modelos agroclimáticos avaliados subestimaram a evapotranspiração de referência estimada pelo modelo padrão de Penman-Monteith, variando de um mínimo de 26,9%, no caso do modelo de Penman, até um máximo de 74,3%, no caso do modelo de Makkink. Os coeficientes de cultura determinados pelo modelo padrão de Penman-Monteith, considerando-se aqui o valor médio dos dois tipos de meloeiros estudados, foram os seguintes: estádio inicial: 0,20; estádio intermediário: 1,10, e estádio final: 0,50.

Associação entre o escore do International Consultation on Incontinence Questionaire: Urinary Incontinence/Short Form e a Avaliação Urodinâmica em mulheres com incontinência urinária

OBJETIVO: Avaliar a correlação entre o International Consultation on Incontinence Questionnaire - Urinary Incontinence/Short Form (ICIQ-UI/SF) e a Avaliação Urodinâmica (AU) em mulheres com incontinência urinária (IU). MÉTODOS: Foram analisados retrospectivamente dados clínicos, AU e escore do ICIQ-UI/SF de 358 mulheres com IU atendidas em clínica privada. O teste de correlação entre ICIQ-UI/SF e os parâmetros urodinâmicos foi o teste de Spearman. Foi utilizada a curva ROC, com os valores de sensibilidade e especificidade dos escores do ICIQ-UI/SF apresentados pelas pacientes, para identificar o valor do questionário que determinasse a presença da alteração urodinâmica estudada. Para o cálculo do valor p foi utilizado o teste do c² ou exato de Fisher. O nível de significância foi de 5% e o software utilizado para análise foi o SAS versão 9.2. RESULTADOS: As pacientes com IU aos Esforços segundo a AU - IUE urodinâmica - representaram 67,3% do total; aquelas com IUE na AU e Hiperatividade Detrusora (HD) - IUM urodinâmica - 16,2%, e as pacientes com HD isolada - HD - 7,3% do total. As pacientes com AU normal representaram 9,2% do total da amostra. Houve associação significativa entre escore ³14 no ICIQ-UI/SF e as pacientes com IUE urodinâmica e IUM urodinâmica. Pacientes com Pressão de Perda ao Esforço (PPE) £90 cmH2O apresentaram escore ao ICIQ-UI/SF³15. O teste de Spearman mostrou correlação inversa fraca entre o escore e a PPE, porém não mostrou correlação entre esse escore e a Capacidade Cistométrica Máxima (CCM) ou com o volume vesical no primeiro desejo miccional. CONCLUSÃO: Houve associação entre o escore do ICIQ-UI/SF e IUE urodinâmica (isolada ou associada à HD); porém não houve associação com a HD isolada. Quanto menor o valor da PPE, maior o escore total do ICIQ-UI/SF. O ICIQ-UI/SF não foi capaz de discriminar o tipo de IU na população estudada.

Desenvolvimento de um modelo experimental de hemodiálise em cães

Com o objetivo de desenvolver um modelo de hemodiálise (HD) em cães, foram estudados 18 animais, sem raça definida, machos, clinicamente sadios, com peso corporal variando entre sete e 14 kg. O acesso vascular foi obtido através de implantação do cateter de duplo lúmen em veia jugular externa. As sessões de HD, em número de cinco por animal, com até três horas de duração, foram realizadas em hemodialisadora de sistema proporcional com ultrafiltração (UF) controlada, com solução dialisante padrão e tampão bicarbonato. A UF foi ajustada para HD isovolêmica, utilizou-se perfil de sódio, e para anticoagulação heparina sódica. Os animais foram mantidos anestesiados com cloridrato de levomepromazina e propofol. Foram avaliados dados hematológicos, bioquímicos, hemogasometria, pressão arterial sistêmica e tempo de coagulação ativado. Foi observada diminuição do número global de hemácias, volume globular, hemoglobina e leucócitos. Em relação aos exames bioquímicos, houve manutenção nos níveis de sódio sérico, e quanto à hemogasometria, a manutenção da SO2. A pressão arterial sistêmica manteve-se constante. Os resultados obtidos no presente trabalho permitiram concluir que foi possível o desenvolvimento do modelo proposto e mostrou que a HD em cães é um método viável e seguro, que poderá contribuir para o tratamento clínico da insuficiência renal nesta espécie.

Oral tolerance induction with altered forms of ovalbumin

As a T cell-dependent phenomenon, oral tolerance is not expected to depend necessarily on native configuration of antigens. We investigated the induction of oral tolerance with modified ovalbumin (Ova). Oral administration of heat-denatured (HD-Ova) and cyanogen bromide-degraded ovalbumin was less effective than native Ova in inducing oral tolerance in B6D2F1 mice. HD-Ova was effective in suppressing delayed-type hypersensitivity (DTH) reactions but did not suppress specific antibody formation. Injection of Ova directly into the stomach, but not into the ileum or cecum, suppressed subsequent immunization to DTH reactions. Gavage with protease inhibitors (aprotinin or ovomucoid) before gavage with Ova was ineffective in blocking tolerance induction. Treatment with hydroxyurea to destroy cycling cells 24 h before gavage with Ova blocked oral tolerance induction and also the possibility to passively transfer tolerance to naive recipients with the serum of mice gavaged with Ova 1 h before. The implications of these findings about oral tolerance induction are discussed

Prevalence and risk factors for HBV, HCV and HDV infections among injecting drug users from Rio de Janeiro, Brazil

Viral hepatitis constitutes a major health issue, with high prevalence among injecting drug users (IDUs). The present study assessed the prevalence and risk determinants for hepatitis B, C and D viruses (HBV, HCV and HDV) infections among 102 IDUs from Rio de Janeiro, Brazil. Serological markers and HCV-RNA were detected by enzyme immunoassay and nested PCR, respectively. HCV genotyping was determined by restriction fragment length polymorphism analysis (RFLP). HBsAg, anti-HBc and anti-HBs were found in 7.8, 55.8 and 24.7% of IDUs, respectively. In the final logistic regression, HBV infection was independently associated with male homosexual intercourse within the last 5 years (odds ratio (OR) 3.1; 95% confidence interval (CI) 1.1-8.8). No subject presented anti-delta (anti-HD). Anti-HCV was detected in 69.6% of subjects, and was found to be independently associated with needle sharing in the last 6 months (OR 3.4; 95% CI 1.3-9.2) and with longer duration of iv drug use (OR 3.1; 95% CI 1.1-8.7). These data demonstrate that this population is at high risk for both HBV and HCV infection. Among IDUs from Rio de Janeiro, unprotected sexual intercourse seems to be more closely associated with HBV infection, whereas HCV is positively correlated with high risk injecting behavior. Comprehensive public health interventions targeting this population and their sexual partners must be encouraged.

The compulsive-like aspect of the head dipping emission in rats with chronic electrolytic lesion in the area of the median raphe nucleus

Head dipping (HD) is a behavioral pattern considered to have a risk assessment or an exploratory role and is used as a complementary parameter to evaluate anxiety in experimental animals. Since rats with electrolytic lesion in the area of the median raphe nucleus displayed high frequencies of HD in a previous study, the present investigation was undertaken to confirm this observation and to determine its anxiety-related origin. HD episodes were counted in adult male Wistar rats (270-350 g) with electrolytic lesion (N = 11) and sham-lesioned controls (N = 12). When HD was measured for 60 min on an elevated open platform, lesioned rats emitted 13 times more HD than controls (264.7 ± 93.3 vs 20.3 ± 7.6 episodes), with the difference being statistically significant (P < 0.05). HD counts during 10-min sessions held 7, 14, 21, 27, and 63 days after lesion showed significantly higher means (range: 28.14 ± 5.38 to 62.85 ± 9.48) compared to sham-lesioned controls (range: 7.37 ± 1.13 to 8.5 ± 1.45). Normal rats stepped down into their home cages when the vertical distance between them and the cage was short (16 cm), and the step-down latencies increased with increasing depths (36.7 ± 7.92 to 185.87 ± 35.44 s). Lesioned rats showed a similar behavior when facing the shortest depth, but had a significantly increased number (23.28 ± 2.35 episodes) and latency (300 ± 0.00 s) of HD compared to normal rats (9.25 ± 1.37 episodes and 185.87 ± 35.44 s) when facing the greatest depth (30 cm). This suggests that HD may be a depth-measuring behavior related to risk assessment.

Effect of hepatitis C serology on C-reactive protein in a cohort of Brazilian hemodialysis patients

Hepatitis C (HCV) is not an uncommon feature in hemodialysis (HD) patients and may be a cause of systemic inflammation. Plasma cytokine interleukin-6 (IL-6) is mainly produced by circulating and peripheral cells and induces the hepatic synthesis of C-reactive protein (CRP), which is the main acute phase reactant. The aim of this study was to investigate the influence of HCV on two markers of systemic inflammation, serum CRP and IL-6, in HD patients. The study included 118 HD patients (47% males, age 47 ± 13 years, 9% diabetics) who had been treated by standard HD for at least 6 months. The patients were divided into two groups depending on the presence (HCV+) or absence (HCV-) of serum antibodies against HCV. Serum albumin (S-Alb), plasma high sensitivity CRP (hsCRP), IL-6, and alanine aminotransferase (ALT) were measured and the values were compared with those for 22 healthy controls. Median hsCRP and IL-6 values and hsCRP/IL-6 ratio were: 3.5 vs 2.1 mg/l, P < 0.05; 4.3 vs 0.9 pg/ml, P < 0.0001, and 0.8 vs 2.7, P < 0.0001, for patients and controls, respectively. Age, gender, S-Alb, IL-6 and hsCRP did not differ between the HCV+ and HCV- patients. However, HCV+ patients had higher ALT (29 ± 21 vs 21 ± 25 IU/l) and had been on HD for a longer time (6.1 ± 3.0 vs 4.0 ± 2.0 years, P < 0.0001). Moreover, HCV+ patients had a significantly lower median hsCRP/IL-6 ratio (0.7 vs 0.9, P < 0.05) compared to the HCV- group. The lower hsCRP/IL-6 ratio in HCV+ patients than in HCV- patients suggests that hsCRP may be a less useful marker of inflammation in HCV+ patients and that a different cut-off value for hsCRP for this population of patients on HD may be required to define inflammation.

Prevalence of hepatitis C virus (HCV) infection and HCV genotypes of hemodialysis patients in Salvador, Northeastern Brazil

Hepatitis C virus (HCV) infection has been identified as the major cause of chronic liver disease among patients on chronic hemodialysis (HD), despite the important reduction in risks obtained by testing candidate blood donors for anti-HCV antibodies and the use of recombinant erythropoietin to treat anemia. A cross-sectional study was performed to estimate the prevalence of HCV infection and genotypes among HD patients in Salvador, Northeastern Brazil. Anti-HCV seroprevalence was determined by ELISA in 1243 HD patients from all ten different dialysis centers of the city. HCV infection was confirmed by RT-PCR and genotyping was performed by restriction fragment length polymorphism. Anti-HCV seroprevalence among HD patients was 10.5% (95% CI: 8.8-12.3) (Murex anti-HCV, Abbott Murex, Chicago, IL, USA). Blood samples for qualitative HCV detection and genotyping were collected from 125/130 seropositive HD patients (96.2%). HCV-RNA was detected in 92/125 (73.6%) of the anti-HCV-positive patients. HCV genotype 1 (77.9%) was the most prevalent, followed by genotype 3 (10.5%) and genotype 2 (4.6%). Mixed infections of genotypes 1 and 3 were found in 7.0% of the total number of patients. The present results indicate a significant decrease in anti-HCV prevalence from 23.8% detected in a study carried out in 1994 to 10.5% in the present study. The HCV genotype distribution was closely similar to that observed in other hemodialysis populations in Brazil, in local candidate blood donors and in other groups at risk of transfusion-transmitted infection.

Striatal and extrastriatal atrophy in Huntington's disease and its relationship with length of the CAG repeat

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder that affects the striatum most severely. However, except for juvenile forms, relative preservation of the cerebellum has been reported. The objective of the present study was to perform MRI measurements of caudate, putamen, cerebral, and cerebellar volumes and correlate these findings with the length of the CAG repeat and clinical parameters. We evaluated 50 consecutive patients with HD using MRI volumetric measurements and compared them to normal controls. Age at onset of the disease ranged from 4 to 73 years (mean: 43.1 years). The length of the CAG repeat ranged from 40 to 69 (mean: 47.2 CAG). HD patients presented marked atrophy of the caudate and putamen, as well as reduced cerebellar and cerebral volumes. There was a significant correlation between age at onset of HD and length of the CAG repeat, as well as clinical disability and age at onset. The degree of basal ganglia atrophy correlated with the length of the CAG repeat. There was no correlation between cerebellar or cerebral volume and length of the CAG repeat. However, there was a tendency to a positive correlation between duration of disease and cerebellar atrophy. While there was a negative correlation of length of the CAG repeat with age at disease onset and with striatal degeneration, its influence on extrastriatal atrophy, including the cerebellum, was not clear. Extrastriatal atrophy occurs later in HD and may be related to disease duration.

Effect of chloride dialysate concentration on metabolic acidosis in aintenance hemodialysis patients

Hyperchloremia is one of the multiple etiologies of metabolic acidosis in hemodialysis (HD) patients. The aim of the present study was to determine the influence of chloride dialysate on metabolic acidosis control in this population. We enrolled 30 patients in maintenance HD program with a standard base excess (SBE) ≤2 mEq/L and urine output of less than 100 mL/24 h. The patients underwent dialysis three times per week with a chloride dialysate concentration of 111 mEq/L for 4 weeks, and thereafter with a chloride dialysate concentration of 107 mEq/L for the next 4 weeks. Arterial blood was drawn immediately before the second dialysis session of the week at the end of each phase, and the Stewart physicochemical approach was applied. The strong ion gap (SIG) decreased (from 7.5 ± 2.0 to 6.2 ± 1.9 mEq/L, P = 0.006) and the standard base excess (SBE) increased after the use of 107 mEq/L chloride dialysate (from -6.64 ± 1.7 to -4.73 ± 1.9 mEq/L, P < 0.0001). ∆SBE was inversely correlated with ∆SIG during the phases of the study (Pearson r = -0.684, P < 0.0001) and there was no correlation with ∆chloride. When we applied the Stewart model, we demonstrated that the lower concentration of chloride dialysate interfered with the control of metabolic acidosis in HD patients, surprisingly, through the effect on unmeasured anions.

Thalamic metabolic abnormalities in patients with Huntington's disease measured by magnetic resonance spectroscopy

Huntington's disease (HD) is a neurologic disorder that is not completely understood; its fundamental physiological mechanisms and chemical effects remain somewhat unclear. Among these uncertainties, we can highlight information about the concentrations of brain metabolites, which have been widely discussed. Concentration differences in affected, compared to healthy, individuals could lead to the development of useful tools for evaluating the progression of disease, or to the advance of investigations of different/alternative treatments. The aim of this study was to compare the thalamic concentration of metabolites in HD patients and healthy individuals using magnetic resonance spectroscopy. We used a 2.0-Tesla magnetic field, repetition time of 1500 ms, and echo time of 135 ms. Spectra from 40 adult HD patients and 26 control subjects were compared. Quantitative analysis was performed using the LCModel method. There were statistically significant differences between HD patients and controls in the concentrations ofN-acetylaspartate+N-acetylaspartylglutamate (NAA+NAAG; t-test, P<0.001), and glycerophosphocholine+phosphocholine (GPC+PCh;t-test, P=0.001) relative to creatine+phosphocreatine (Cr+PCr). The NAA+NAAG/Cr+PCr ratio was decreased by 9% and GPC+PCh/Cr+PCr increased by 17% in patients compared with controls. There were no correlations between the concentration ratios and clinical features. Although these results could be caused by T1 and T2 changes, rather than variations in metabolite concentrations given the short repetition time and long echo time values used, our findings point to thalamic dysfunction, corroborating prior evidence.