Finger Prosthesis Driven by DEA Pairs as Agonist-Antagonist Artificial Muscles.

Loss of an upper limb exerts a negative influence on an individual's ability to perform their activities of daily living (ADLs), reducing quality of life and self-esteem. A prosthesis capable of performing basic ADLs functions has the capability of restoring independence and autonomy to amputees. However, current technologies present in robotic prostheses are based on rigid actuators with several drawbacks, such as high weight and low compliance. Recent advances in robotics have allowed for the development of flexible actuators and artificial muscles to overcome the limitations of rigid actuators. Dielectric elastomer actuators (DEAs) consist of a thin elastomer membrane arranged between two compliant electrodes capable of changing dimensions when stimulated with an electrical potential difference. In this work, we present the design and testing of a finger prosthesis driven by two DEAs arranged as agonist-antagonist pairs as artificial muscles. The soft actuators are designed as fiber-constrained dielectric elastomers (FCDE), enabling displacement in just one direction as natural muscles. The finger prosthesis was designed and modeled to show bend movement using just one pair of DEAs and was made of PLA in an FDM 3D printer to be lightweight. The experimental results show great agreement with the proposed model and indicate that the proposed finger prosthesis is promising in overcoming the limitations of the current rigid based actuators.

Nutritional intervention in acute diarrhea: is a lactose-free formula essential?

A prospective study was done to determine the incidence of disaccharide intolerance among 3-36 month-old patients with acute watery diarrhea who were on breast feeding and/or lactose-containing formula. The effect of feeding intervention on the outcome was investigated. Significant disaccharide intolerance was defined as one with (1) biochemical derangements: stool pH < 6.0 (Riedel de Haen pH paper) and reducing substances > or = 0.5 mg% (Clinitest) on two consecutive determinations and (2) clinical evidence: high purging rate (> 10 gm/kg/hour) and reappearance of dehydration and/or weight loss while on a lactose containing milk. Seven of 92 patients (7.8%) had biochemical evidence of disaccharide malabsorption on admission. Subsequent monitoring of the study population showed absence of disaccharide intolerance. Despite a lactose containing formula, a significant (p < 0.05) reduction in stool output from the first to the second day (145.85 +/- 130.26 vs 115.43 +/- 95.65 g/kg admission weight) was noted. Likewise, weight gain from admission to discharge (4.56 +/- 3.44%) was observed. The mean total duration of illness (4.75 +/- 2.84 days) was well within the usual course of five to seven days. This study supports the current recommendation of continued breast feeding and/or use of lactose containing formula during acute watery diarrhea.

Effect of vitamin A deficiency on the adherence of fimbriated and nonfimbriated Salmonella typhimurium to isolated small intestinal enterocytes.

In vitamin A-deficient children, increased rates of bacterial infections in the intestine have been observed. The adherence of bacteria is a prerequisite for invasion. Thus, the effect of vitamin A deficiency on the adherence of fimbriated and nonfimbriated Salmonella typhimurium to isolated small intestinal enterocytes was studied. Male weanling rats matched by weight were divided into three groups: one group was fed a vitamin A-free diet for 8-12 weeks; another was given the same diet supplemented with retinol acetate; a third group matched for age served as controls. The vitamin A-deficient group showed a significantly lower growth rate and lower serum retinol levels than either the retinol acetate-supplemented or control groups. In all the groups, S. typhimurium possessing mannose-sensitive fimbriae adhered to enterocytes in significantly larger numbers than the nonfimbriated strains. The number of fimbriated S. typhimurium bound to enterocytes from the proximal small intestine was significantly higher in the vitamin A-deficient rats than in the pair-fed vitamin A-supplemented group (19.3 +/- 14.9 versus 7.8 +/- 5.0; p less than 0.05) or the control group (19.3 +/- 14.9 versus 8.7 +/- 3.5, p = 0.01). The specific activities of the enterocytes lactase, sucrase, and maltase and the protein content in the vitamin A-deficient rats were similar to those in the controls. These results demonstrate that vitamin A deficiency in rats is associated with the increased ability of S. typhimurium to adhere to proximal small intestinal enterocytes. However, the possible changes in the membrane of the enterocyte do not include decreases in brush border disaccharidases or protein content.