RESUMO
Bacterial cell surface hydrophobicity is a relevant property in determining the ability of bacteria to adhere to inert surfaces. This property has been measured using the microbial adhesion to hydrocarbon (MATH) test. Several reports in the literature establish the percentage of adhesion to hydrocarbons (PoAtH) value produced by the MATH test for a broad variety of bacteria. Discrepancies in PoAtH values reported for the same strain of a specific microorganism suggest that some method-induced variation may exist, as different research teams employ different versions of the assay. The objective of the present study was to compare the performance of different versions of the MATH test as reported in the literature, to quantify the magnitude of the method-induced variation on PoAtH values. The study demonstrated that PoAtH values are influenced twice as much by variations in the employed assay than by actual differences in cell surface composition or architecture. The two L. reuteri strains studied responded differently to changes in assay conditions showing 40 and 70% method-dependent variation for strain ATCC 53609 and 55730, respectively. These results highlight the need to properly standardize the MATH test to enable comparison of PoAtH values produced by independent research teams.
Assuntos
Aderência Bacteriana , Bioensaio/métodos , Membrana Celular/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Humanos , Hidrocarbonetos/metabolismo , Limosilactobacillus reuteri , TemperaturaRESUMO
Abstract Objective: To compare the ways of evaluating arithmetic skills in Brazilian children with ADHD by combining three validated neuropsychological tests and determining whether they are sensitive to the methylphenidate treatment. Methods: Forty-two children (9‒12 years old) participated in the present study: 20 were children with ADHD (DSM-IV) and 22 were age-matched controls. A classification criterion was used for each test separately and one, for their combination to detect the presence of arithmetic difficulties at two time points: baseline (time 1); and when children with ADHD were taking 0.3‒0.5 mg/kg of methylphenidate (time 2). The study also assessed children's subtraction performance, combining parts of these tests. Results: Separately, the tests were only sensitive to differences between groups without medication. However, by combining the three neuropsychological tests, we observed a difference and detected a reduction in arithmetic difficulties associated with the methylphenidate treatment. The same effects were found in subtraction exercises, which require a borrowing procedure. Conclusions: The present study detected arithmetic difficulties in Brazilian children with ADHD and the effects of methylphenidate. Given this improvement in sensitivity, combining tests could be a promising alternative when working with limited samples.
Resumo Objetivo: Comparar as formas de avaliar as habilidades aritméticas em crianças brasileiras com TDAH, combinando três testes neuropsicológicos validados, e verificar se são sensíveis ao tratamento com metilfenidato. Métodos: Quarenta e duas crianças (9‒12 anos) participaram deste estudo: 20 eram crianças com TDAH (DSM-IV) e 22 eram controles pareados por idade. Usamos um critério de classificação para cada teste separadamente e outro para a combinação entre eles, visando detectar a presença de dificuldades aritméticas em dois momentos: início (tempo 1) e quando as crianças com TDAH estavam tomando 0,3‒0,5 mg/kg de metilfenidato (tempo 2). O estudo também avaliou o desempenho dessas crianças em operações de subtração, combinando partes desses testes. Resultados: Separadamente, os testes foram sensíveis apenas às diferenças entre os grupos sem medicação. Entretanto, ao combinar os três testes neuropsicológicos, foi possível observar uma diferença e detectar uma redução das dificuldades aritméticas associadas ao tratamento com metilfenidato. Os mesmos efeitos foram encontrados em exercícios de subtração que exigem o procedimento de empréstimo. Conclusões: O estudo foi capaz de detectar dificuldades aritméticas em crianças brasileiras com TDAH e os efeitos do metilfenidato. Dada essa melhora na sensibilidade, combinar testes poderia ser uma alternativa promissora ao trabalhar com amostras limitadas.