Resumo Estudos epidemiológicos recentes mostraram que os padrões alimentares podem ter um impacto mais persistente sobre o risco de formação de cálculos do que apenas os nutrientes da dieta. A dieta DASH (Dietary Approaches to Stop Hypertension), uma dieta pobre em sódio e rica em frutas/vegetais, tem sido associada a um menor risco de nefrolitíase, devido às alterações metabólicas urinárias. Este estudo observacional teve como objetivo investigar se o padrão alimentar de pacientes litiásicos (Lit) se assemelhava a uma dieta estilo DASH e sua influência nos parâmetros litogênicos urinários. Dados antropométricos, amostra de soro em jejum, amostras de urina de 24 horas e um registro de ingestão alimentar de 3 dias sob dieta irrestrita foram obtidos de 222 Lit e comparados com 136 indivíduos não-Lit (controles). As porções de alimentos do padrão de dieta DASH foram determinadas a partir dos registros alimentares, enquanto a ingestão de cloreto de sódio (NaCl) e proteína (Equivalente Protéico do Aparecimento de Nitrogênio Urinário, PNA) foram estimadas a partir da uréia e sódio urinários de 24 horas. Um perfil alimentar próximo a uma dieta estilo DASH não foi observado em nenhum dos grupos. A ingestão de NaCl e PNA foram significativamente maiores nos Lit versus não-Lit (12,0 ± 5,2 v.s. 10,1 ± 3,4 g/dia, p = 0,01 e 1,8 ± 0,1 v.s. 1,4 ± 0,1 g/kg/dia, p = 0,03). Os Lit exibiram uma correlação positiva entre a ingestão de NaCl e PNA com cálcio, oxalato e ácido urinários, e de PNA com sódio urinário. Os Lit consumiram mais vegetais e leguminosas, mas menos frutas e lácteos com teor reduzido de gordura do que os não-Lit. A presente série apresentou um padrão alimentar caracterizado por reduzido consumo de cálcio e elevado em sal e proteínas, não refletindo um padrão ideal de dieta DASH.

Abstract Recent epidemiological studies have shown that dietary patterns may have a more persistent impact on the risk of stone formation than single nutrients of the diet. Dietary Approaches to Stop Hypertension (DASH), a low-sodium and fruits/vegetables-rich diet, has been associated with a lower risk of nephrolithiasis, due to altered urinary biochemistry. This observational study aimed to investigate whether the dietary pattern of stone formers (SF) resembled a DASH-diet and its influence on urinary lithogenic parameters. Anthropometric data, fasting serum sample, 24-h urine samples, and a 3-day food intake record under an unrestricted diet were obtained from 222 SF and compared with 136 non-SF subjects (controls). The DASH-diet food portions were determined from the food records whereas intakes of sodium chloride (NaCl) and protein (protein equivalent of nitrogen appearance, PNA) were estimated from 24-hr urinary sodium and urea. A dietary profile close to a DASH-diet was not observed in any of the groups. NaCl intake and PNA were significantly higher in SF versus non-SF (12.0 ± 5.2 v.s. 10.1 ± 3.4 g/day, p = 0.01 and 1.8 ± 0.1 v.s. 1.4 ± 0.1 g/kg/day, p = 0.03). SF exhibited a positive correlation of NaCl intake and PNA with urinary calcium, oxalate and uric acid, and of PNA with urinary sodium. SF consumed more vegetables and legumes, but less fruits and low-fat dairy items than non-SF. The present series presented a dietary profile characterized by low calcium and high salt and protein contents, not reflecting an ideal DASH-style diet pattern.

ABSTRACT Expansive clay soils are a problem for agriculture and engineering because they are susceptible to change in volume due to seasonal variation in water content and temperature. One of its morphological properties is slickensides, which result from the ability to contract and crack when dry and expand by wetting. The objective of this study was to evaluate the processes of expansion and formation and propagation of cracks due to the change in water content over time. The expansion process was evaluated through simple edometric tests with different external stress values applied to undisturbed soil samples. To evaluate the shrinking process, a device was developed to monitor the process of crack propagation. The mechanisms through which cracks begin and develop were studied using molded soil samples at the liquidity limit and at 1.25 times the liquidity limit with a drying and wetting cycle. Crack initiation conditions and development of geometric crack indices were measured with the water content and drying time. The soil presented medium to high expansion that depends on the overburden and suction applied, and the swelling stress was found to increase as suction increases. The changes in volume due to wetting and the propagation of cracks due to drying developed in three stages: initial, primary, and secondary. In the initial stage, few cracks or swelling occur with gradual variation in water content. As the water content approaches the limit of soil contraction (in the drying process) or the limit of soil saturation (in the wetting process), cracks and expansion developed slowly and approach a secondary stage. In the primary stage, cracks and expansion occurred rapidly with drying or wetting, respectively. Drying and wetting cycles showed similar crack patterns with the appearance of new micro-cracks during each new drying cycle.