The role for the metabolism of hyaluronic acid in the repair process is uncertain. Fetal dermal wounds do not heal by scarring and have sustained high levels of hyaluronic acid. In contrast, adult dermis is repaired by scarring and has less hyaluronic acid. Initially after injury, hyaluronic acid is elevated in both adult and fetal wounds, and although it remains elevated in fetal repair, it is rapidly degraded in adult wounds. The chronic addition of hyaluronic acid or hyaluronidase to polyvinyl alcohol sponge implants in adult mice was investigated in this study. Polyvinyl alcohol sponge implants containing a central reservoir were placed subcutaneously in the dorsum of adult male CD-1 mice. Mice were divided into three groups: a phosphate-buffered saline control, a 20 microgram hyaluronic acid treatment group, and a 10 U hyaluronidase treatment group. The central reservoir of each sponge implant received appropriate compound every 3 days for 2 weeks via transdermal injection and were then evaluated histologically. At 2 weeks, the cellular density and the quantity of granulation tissue deposition were the greatest in the hyaluronidase group and were lowest in the hyaluronic acid group. In addition, the organization of collagen fiber bundles was the most dense in the hyaluronidase group and least in the hyaluronic acid group. In a second experiment, polyvinyl alcohol sponge implants in mice received either phosphate-buffered saline solution or 20 microgram hyaluronic acid every 3 days for 1 week. On day 5, an aliquot of fluorescently tagged native collagen was injected into the sponges. Sponges were harvested at day 7, cryosections made, and the presence of autofluorescent collagen fibers assessed. The autofluorescent collagen fiber bundles in the phosphate-buffered saline solution group were organized in thick parallel bundles, whereas the collagen bundles from hyaluronic acid-treated implants were organized in fine lacelike structures. Chronic addition of hyaluronic acid appears to mimic the fetal dermal connective tissue matrix in which repair proceeds with diminished collagen deposition, organized in finer collagen fiber bundles in granulation tissue. On the other hand, the removal of hyaluronic acid by the chronic administration of hyaluronidase increases the amount of granulation tissue. Elevated levels of hyaluronic acid in granulation tissue appear to modulate the ability of resident fibroblasts to organize collagen fiber bundles.

Adjuvants, Immunologic↗

PubMedDate not supplied

Ten trends in women's health.

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Consumer Advocacy↗

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Anemia severity and missed dialysis treatments in erythropoietin-treated hemodialysis patients.

Neither the sociodemographic correlates nor the biochemical/clinical consequences of missed dialysis treatments have been well defined. During a 10 week period, the authors enumerated missed dialysis treatments among 430 patients randomly selected from a pool of 1,395 hemodialysis patients. A forward logistic regression model was used to determine whether a relationship existed between missed dialysis treatments and the following independent variables: age, gender, race, renal diagnosis, length of time on maintenance hemodialysis, co-morbidity index, modified Karnofsky score, employment status, household residents, and laboratory indices. Forty-three (10%) of 430 patients missed a total of 96 treatments. Despite equivalent treatment with erythropoietin, patients who missed dialysis treatment(s) had a lower mean hematocrit (27 +/- 4.3%) at the end of the study than those patients who underwent all treatments (29 +/- 4.5%) (p = 0.0287). Mean serum albumin and creatinine levels were equivalent in compliant and noncompliant patients. Recent starts (p = 0.0048), and younger patients (p = 0.0424) were most likely to miss dialysis treatment(s). One of the major consequences of missed dialysis treatment(s) is exacerbation of anemia, and younger patients and freshly started patients are more likely to miss scheduled dialysis treatments than their respective counterparts.

Adult↗