Rat sciatic nerve regeneration in semipermeable artificial tubes

The regeneration of the sciatic nerve in Wistar rats across a 10-mm gap, within a semipermeable chamber was examined. The sequence of regeneration can be summarized as follows: (i) formation of a fibrin-containing matrix; (ii) invasion of this matrix by fibroblasts, forming two populations defined by their relative position within the matrix; (iii) the appearance of blood vessels; (iv) bridge formation; and (v) colonization of the bridge by nerve fibers. After 4 weeks, the number of myelinated fibers and the regenerate surface were studied at midtube level. Two and four weeks after the operation, both myelinated and unmyelinated leading fibers were detected and their distances from proximal stump measured. The results approach those reported in the literature for impermeable tubes, but not those obtained for fully permeable ones.     

Improvement of the nutritional condition with hypocaloric peripheral parenteral nutrition (HPPN) in the immediate postoperative period of elective abdominal surgery

Thirty-one patients scheduled for elective surgery for non-malignant abdominal disease were randomized during the first five postoperative days to two different schedules. Group I received water, electrolytes and glucose. Group II received a standard solution containing crystalline amino acids (3.8 g/l), xylitol (25 g/l) and sorbitol (25 g/l), accounting for a total of 900 cal/day. Evaluation was made with clinical, anthropometric and biochemical parameters. Among others, the following significant differences were observed at the end of the study: retinol bound protein: in group I, 4.25 +/- 1.3 and in group II, 5.38 +/- 1.53 (p less than 0.05); prealbumin: in group I, 18.7 +/- 6.24 and in group II, 24.51 +/- 7 (p less than 0.05). The significantly higher values of short-life plasma proteins observed in group II indicate that with HPPN a higher synthesis of visceral protein is promoted. These data demonstrate that HPPN improves the nutritional state during the postoperative period.     

Determination of adenosine effects and adenosine receptors in murine corpus cavernosum

This study tested the hypothesis that adenosine, in murine corpora cavernosa, produces direct relaxation of smooth muscle cells and inhibition of contractile responses mediated by sympathetic nerve stimulation. Penes were excised from anesthetized male C57BL/6 mice, dissected, and cavernosal strips were mounted to record isometric force. Adenosine, 2-chloroadenosine (stable analog of adenosine), and 2-phenylaminoadenosine (CV1808) (A2(A)/A2(B) agonist) produced concentration-dependent relaxations of phenylephrine-contracted tissues. Relaxation to 2-chloroadenosine was inhibited, in a concentration-dependent manner, by 2-(2-furanyl)-7-(2-phenylethyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine (SCH58261; A2(A) antagonist; 10(-9)-10(-6) M) and N-(4-acetylphenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)phenoxy]acetamida (MRS1706; A2(B) antagonist; 10(-8)-10(-6) M). The combination of both antagonists abrogated 2-chloroadenosine-induced relaxation. Electrical field stimulation (EFS; 1-32 Hz) of adrenergic nerves produced frequency-dependent contractions that were inhibited by compounds that increase adenosine levels, such as 5'-iodotubercidin (adenosine kinase inhibitor), erythro-9-(2-hydroxy-3-nonyl)adenine (adenosine deaminase inhibitor), and dipyridamole (inhibitor of adenosine transport). The adenosine A1 receptor agonist N(6)-cyclopentyladenosine (C8031) right-shifted contractile responses to EFS, with a significant inhibitory effect at 10(-6) M. Blockade of adenosine A1 receptors with 8-cyclopentyl-1,3-dipropylxanthine (C101) (10(-7) M) enhanced contractile responses to EFS and eliminated the inhibitory effects of 5'-iodotubercidin. Dipyridamole and 5'-iodotubercidin had no effect on adenosine-mediated relaxation. In summary, adenosine directly relaxes cavernosal smooth muscle cells, by the activation of A2(A)/A2(B) receptor subtypes. In addition, adenosine negatively modulates sympathetic neurotransmission, by A1 receptor subtype activation, in murine corpora cavernosa. Adenosine may subserve dual roles in modulating the physiological mechanisms of erection in mice.     

Vitamin D receptor gene polymorphisms and susceptibility M. tuberculosis in native Paraguayans

Tuberculosis (TB) is a significant health problem for most of the world's populations, and prevalence among indigenous groups is typically higher than among their nonindigenous neighbors. Native South Americans experience high rates of TB, but while research in several other world populations indicates that susceptibility is multifactorial, polygenic, and population-specific, little work has been undertaken to investigate factors involved in Native American susceptibility. We conducted a family-based association study to examine immunologically relevant polymorphisms of a candidate gene, the vitamin D receptor, in conjunction with three measures of TB status in two Native Paraguayan populations, the Aché and the Avá. This is the first large-scale genetic analysis of Native South Americans to examine susceptibility to both infection and disease following exposure to M. tuberculosis. These two types of susceptibility reflect differences in innate and acquired immunity that have proven difficult to elucidate in other populations. Our results indicate that among the Aché, the FokI F allele protects individuals from infection, while the TaqI t allele protects against active disease but not infection. In particular, FF homozygotes are 17 times more likely to test positive for exposure to TB, but no more likely to have ever been diagnosed with active TB. TT individuals are 42 times less likely to mount a delayed-type hypersensitivity response, and the T allele was significantly more likely to have been transmitted to offspring who have been diagnosed with active TB. This ongoing research is of vital importance to indigenous groups of the Americas, because if there is a population-specific component to TB susceptibility, it will likely prove most effective to incorporate this into future treatment and prevention strategies.