RESUMO Rhipicephalus (Boophilus) microplus (Canestrini) é um dos parasitas que mais impactam a pecuária de países tropicais e subtropicais, incluindo o Brasil, com perdas em torno de US$ 3,24 bilhões por ano. Ocorrências de populações resistentes a diferentes classes de acaricidas e suas associações têm sido amplamente diagnosticadas em todo o Brasil. Para isso, bioensaios utilizando o teste de pacote larval (LPT) impregnado com cipermetrina e diazinon em diferentes concentrações foram realizados para caracterizar a resistência fenotípica (nível de resistência, RL), a resistência molecular (mutação no domínio III - S6 T2134A) e o metabolismo enzimático do diazinon e da cipermetrina em algumas populações de R. (Boophilus) microplus coletadas em diferentes regiões do estado de São Paulo. Dentre as 40 propriedades analisadas, 18 delas apresentaram fatores de resistência à cipermetrina, sendo RL I (53%) e RL II (47%). A mutação do domínio III T2134A foi encontrada pela primeira vez no Brasil, em sete fazendas. Larvas heterozigotas foram constatadas em seis delas, e larvas homozigotas resistentes em quatro. Nenhuma diferença (P>0,05) na atividade enzimática de α-esterase e β-esterase foi observada em testes com larvas vivas e mortas em uma concentração de cipermetrina de 409,6μg/cm2. Noventa por cento das propriedades apresentaram resistência ao agente ativo diazinon: RL I em 6%, RL II em 30% e RL III em 64%. Houve diferenças significativas (P<0,05) na atividade enzimática na concentração mais elevada (3,2μg/cm2) entre os grupos de larvas vivas e mortas.

ABSTRACT Rhipicephalus (Boophilus) microplus is one of the parasites that has an impact on livestock farming in Brazil. Bioassays using the larval packet test (LPT) impregnated with cypermethrin and diazinon at different concentrations were performed to characterize phenotypic resistance (resistance level, RL), molecular resistance (mutation in domain III - S6 T2134A) and enzymatic metabolism of diazinon and cypermethrin in some populations of R. microplus that were collected in different regions of the state of São Paulo. Among the 40 farms analyzed, 18 of them presented resistance factors for cypermethrin, with RL I (53%) and RL II (47%). Mutation of domain III T2134A was found for the first time in Brazil, on seven farms. Heterozygous larvae were found on six of them and resistant homozygous larvae on four. No differences (p>0.05) in enzymatic activity of α-esterase and β-esterase were found in tests with live and dead larvae at a cypermethrin concentration of 409.6μg/cm2. Ninety percent of the farms showed resistance to the active agent diazinon: RL I in 6%, RL II in 30% and RL III in 64%. There were significant differences (p<0.05) in enzymatic activity at the highest concentration (3.2μg/cm2).

We evaluated changes in glucose tolerance of 17 progressors and 62 non-progressors for 9 years to improve our understanding of the pathogenesis of type 2 diabetes mellitus. Changes in anthropometric measurements and responses to an oral glucose tolerance test (OGTT) were analyzed. We identified 14 pairs of individuals, one from each group, who were initially normal glucose tolerant and were matched for gender, age, weight, and girth. We compared initial plasma glucose and insulin curves (from OGTT), insulin secretion (first and second phases) and insulin sensitivity indices (from hyperglycemic clamp assay) for both groups. In the normal glucose tolerant phase, progressors presented: 1) a higher OGTT blood glucose response with hyperglycemia in the second hour and a similar insulin response vs non-progressors; 2) a reduced first-phase insulin secretion (2.0 ± 0.3 vs 2.3 ± 0.3 pmol/L; P < 0.02) with a similar insulin sensitivity index and a lower disposition index (3.9 ± 0.2 vs 4.1 ± 0.2 µmol·kg-1·min-1 ; P < 0.05) vs non-progressors. After 9 years, both groups presented similar increases in weight and fasting blood glucose levels and progressors had an increased glycemic response at 120 min (P < 0.05) and reduced early insulin response to OGTT (progressors, 1st: 2.10 ± 0.34 vs 2nd: 1.87 ± 0.25 pmol/mmol; non-progressors, 1st: 2.15 ± 0.28 vs 2nd: 2.03 ± 0.39 pmol/mmol; P < 0.05). Theses data suggest that β-cell dysfunction might be a risk factor for type 2 diabetes mellitus.

In this work we study a transmission problem for the model of beams developed by S.P. Timoshenko [10]. We consider the case of mixed material, that is, a part of the beam has friction and the other is purely elastic. We show that for this type of material, the dissipation produced by the frictional part is strong enough to produce exponential decay of the solution, no matter how small is its size. We use the method of energy to prove exponential decay for the solution.

Hexane, ethanol and aqueous extracts and fractions from leaves of Pouteria torta (Mart.) Radlk (Sapotaceae), a perennial tree, widespread in the Brazilian Cerrado, were tested for cytotoxicity with the Artemia salina toxicity model. Only the aqueous crude extract and the MeCN:CHCl3 fraction of the ethanol extract presented toxicity (0.28 mg/mL and 0.27mg/mL, respectively). Lupeol acetate was isolated from the hexane extract. It is the first report of lupeol acetate from the genus Pouteria.

To identify early metabolic abnormalities in type 2 diabetes mellitus, we measured insulin secretion, sensitivity to insulin, and hepatic insulin extraction in 48 healthy normal glucose-tolerant Brazilians, first-degree relatives of type 2 diabetic patients (FH+). Each individual was matched for sex, age, weight, and body fat distribution with a person without history of type 2 diabetes (FH-). Both groups were submitted to a hyperglycemic clamp procedure (180 mg/dl). Insulin release was evaluated in its two phases. The first was calculated as the sum of plasma insulin at 2.5, 5.0, 7.5, and 10.0 min after the beginning of glucose infusion, and the second as the mean plasma insulin level in the third hour of the clamp procedure. Insulin sensitivity index (ISI) was the mean glucose infusion rate in the third hour of the clamp experiment divided by the mean plasma insulin concentration during the same period of time. Hepatic insulin extraction was determined under fasting conditions and in the third hour of the clamp procedure as the ratio between C-peptide and plasma insulin levels. FH+ individuals did not differ from FH- individuals in terms of the following parameters [median (range)]: a) first-phase insulin secretion, 174 (116-221) vs 207 (108-277) µU/ml, b) second-phase insulin secretion, 64 (41-86) vs 53 (37-83) µU/ml, and c) ISI, 14.8 (9.0-20.8) vs 16.8 (9.0-27.0) mg kg-1 min-1/µU ml-1. Hepatic insulin extraction in FH+ subjects was similar to that of FH- ones at basal conditions (median, 0.27 vs 0.27 ng/µU) and during glucose infusion (0.15 vs 0.15 ng/µU). Normal glucose-tolerant Brazilian FH+ individuals well-matched with FH- ones did not show defects of insulin secretion, insulin sensitivity, or hepatic insulin extraction as tested by hyperglycemic clamp procedures.

Mechanical ventilation with high tidal volumes (V T) has been shown to induce lung injury. We examined the hypothesis that this procedure induces lung injury with inflammatory features. Anesthetized male Wistar rats were randomized into three groups: group 1 (N = 12): V T = 7 ml/kg, respiratory rate (RR) = 50 breaths/min; group 2 (N = 10): V T = 21 ml/kg, RR = 16 breaths/min; group 3 (N = 11): V T = 42 ml/kg, RR = 8 breaths/min. The animals were ventilated with fraction of inspired oxygen of 1 and positive end-expiratory pressure of 2 cmH2O. After 4 h of ventilation, group 3, compared to groups 1 and 2, had lower PaO2 [280 (range 73-458) vs 517 (range 307-596), and 547 mmHg (range 330-662), respectively, P<0.05], higher wet lung weight [3.62 ± 0.91 vs 1.69 ± 0.48 and 1.44 ± 0.20 g, respectively, P<0.05], and higher wet lung weight/dry lung weight ratio [18.14 (range 11.55-26.31) vs 7.80 (range 4.79-12.18), and 6.34 (range 5.92-7.04), respectively, P<0.05]. Total cell and neutrophil counts were higher in group 3 compared to groups 1 and 2 (P<0.05), as were baseline TNF-alpha concentrations [134 (range <10-386) vs 16 (range <10-24), and 17 pg/ml (range <10-23), respectively, P<0.05]. Serum TNF-alpha concentrations reached a higher level in group 3, but without statistical significance. These results suggest that mechanical ventilation with high V T induces lung injury with inflammatory characteristics. This ventilatory strategy can affect the release of TNF-alpha in the lungs and can reach the systemic circulation, a finding that may have relevance for the development of a systemic inflammatory response.