Safety assessment of nylon as used in cosmetics.

The Cosmetic Ingredient Review Expert Panel (Panel) reviewed the safety of nylon polymers, which function in cosmetics primarily as bulking and opacifying agents. The Panel reviewed relevant animal and human data related to these large polymers and determined that they are not likely to penetrate the skin. Whatever residual monomers may be present were not present at a sufficient level to cause any reactions in test subjects at the maximum ingredient use concentration. Accordingly, the Panel concluded that these ingredients are safe in the present practices of use and concentration.

Choice of hemostatic agent influences adhesion formation in a rat cecal adhesion model.

INTRODUCTION: Hemostatic agents are frequently used during abdominal surgery and some are linked to adhesion formation. We sought to evaluate the impact of several commonly used hemostatic agents on adhesion formation in a rat peritoneal model. METHODS: In our study, Wister outbred rats underwent laparotomy and excision of a portion of their peritoneum to initiate adhesion formation process. One of six different hemostatic agents, namely, activated starch microspheres (Arista AH; Medafor Inc., Minneapolis, MN), glutaraldehyde activated collagen (BioGlue; Cryolife Inc., Kennesaw, GA), thrombin coated collagen microspheres (FloSeal; Baxter Inc., Deerfield, IL), thrombin activated fibrin polymer (Tisseel, Baxter), polyethylene glycol polymer (CoSeal, Baxter), or oxidized cellulose (Surgicel; Ethicon Inc., Somerville, NJ), was placed in the area of peritoneal defect. All animals were sacrificed on post-op day 7 and strength and extent of adhesion formation was determined. Histopathological examination of rat caecum was also performed. RESULTS: Arista and CoSeal showed significantly lower adhesion formation than controls (P < 0.05). Higher adhesion scores were seen in BioGlue (P < 0.05) treated rats. Additionally, histopathologic examination showed that BioGlue caused statistically more inflammation and necrosis than controls (P < 0.05). Total adhesion score increased with residual amount of agent present at 7 d. CONCLUSIONS: Use of Arista and CoSeal may help in reducing peritoneal adhesions after intra-abdominal surgeries. Furthermore, there appears to be a relationship between the creation of inflammation and necrosis in tissues and the eventual formation of adhesions. This could aid in improving the design of these agents in the future.

Comparison of a chymase inhibitor and hyaluronic acid/carboxymethylcellulose (Seprafilm) in a novel peritoneal adhesion model in rats.

Adhesion formation that occurred after alkali-induced injury of the cecum was used as a novel adhesion model in rats, and it was compared with that of a common adhesion model after abrading the cecum. Using the novel adhesion model, inhibition of adhesion formation by a chymase inhibitor, Suc-Val-Pro-PheP(OPh)2, and by sodium hyaluronate/carboxymethylcellulose (Seprafilm) was evaluated, and their mechanisms were assessed. The degree of adhesion formation was more severe and more stable in the alkali-induced injury model than in the abrasion-induced injury model. Both the chymase inhibitor and Seprafilm showed significant attenuation of the degree of adhesion 14 days after alkali-induced injury. Chymase activity in the cecum was significantly increased after alkali-induced injury, but it was significantly attenuated by the chymase inhibitor and Seprafilm. Myeloperoxidase and transforming-growth factor (TGF)-ß levels were significantly increased after alkali-induced injury, but they were attenuated by both the chymase inhibitor and Seprafilm. At the level of the adhesions, the numbers of both chymase-positive cells and TGF-ß-positive cells were significantly increased, but their numbers were reduced by the chymase inhibitor and Seprafilm. In conclusion, a chymase inhibitor attenuated the degree of adhesions to the same degree as Seprafilm in a novel peritoneal adhesion model that was more severe and more stable than the common adhesion model, and not only the chymase inhibitor, but also Seprafilm reduced the chymase increase at the adhesions.

An experimental, non-uremic rabbit model of peritoneal dialysis.

Peritoneal dialysis (PD) is a well established method of depuration in uremic patients. Standard dialysis solutions currently in use are not biocompatible with the peritoneal membrane. Studying effects of dialysate on peritoneal membrane in humans is still a challenge. There is no consensus on the ideal experimental model so far. We, therefore, wanted to develop a new experimental non-uremic rabbit model of peritoneal dialysis, which would be practical, easy to conduct, not too costly, and convenient to investigate the long-term effect of dialysis fluids. The study was done on 17 healthy Chinchilla male and female rabbits, anesthetized with Thiopental in a dose of 0.5 mg/kg body mass. A catheter, specially made from Tro-soluset (Troge Medical GMBH, Hamburg, Germany) infusion system, was then surgically inserted and tunneled from animals' abdomen to their neck. The planned experimental procedure was 4 weeks of peritoneal dialysate instillation. The presented non-uremic rabbit model of peritoneal dialysis is relatively inexpensive, does not require sophisticated technology and was well tolerated by the animals. Complications such as peritonitis, dialysis fluid leakage, constipation and catheter obstruction were negligible. This model is reproducible and can be used to analyze the effects of different dialysis solutions on the rabbit peritoneal membrane.

The prevention of peritoneal adhesions by in situ cross-linking hydrogels of hyaluronic acid and cellulose derivatives.

Post-operative peritoneal adhesions can cause pelvic pain, infertility, and potentially lethal bowel obstruction. We have designed and synthesized injectable hydrogels that are formed by mixing hydrazide-modified hyaluronic acid (HA) with aldehyde-modified versions of cellulose derivatives such as carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), and methylcellulose (MC). Gelation of these hydrogels occurred in less than 1 min, and had higher shear moduli than that of HA-HA gel (HAX). Hydrogels degraded in the presence of hyaluronidase in vitro, with HA-MC and HA-HPMC degrading more slowly than HAX and HA-CMC. The aldehyde-modified cellulose derivatives showed dose-dependent mild-to-moderate cytotoxicity to mesothelial cells and macrophages in vitro, but all were biocompatible in the murine peritoneum, causing no adhesions for 3 weeks. All the cellulose-derived gels showed efficacy in reducing the area of adhesion formation in a rabbit sidewall defect-bowel abrasion model.

Tranexamic acid-associated ligneous conjunctivitis with gingival and peritoneal lesions.

A considerable number of agents have been proposed as causing ligneous conjunctivitis. We report the first case to arise as a side effect of tranexamic acid (Cyclokapron), an anti-fibrinolytic drug used in the treatment of menorrhagia. In addition to the typical conjunctival changes our patient had lesions affecting the gingiva and the peritoneum the last causing considerable protein loss into the peritoneal cavity.

What's new in intraperitoneal test on Kevlar (asbestos substitute)?

The intraperitoneal test is a suitable experimental method for studying the different patterns of morphological reaction to foreign body substances of various kinds and concentrations as well as their transport within and elimination from the organism, Kevlar fibres are synthetic aromatic polyamid (aramid) fibres which, investigated by means of the intraperitoneal test in Wistar rats, show distinct pathogenetic reaction patterns: 1. In the early stage after application, the formation of multinucleated giant cells with phagocytosis of the amber-coloured Kevlar fibres, and an inflammatory reaction are foremost features. 2. The typical feature of the second stage is the development of granulomas with central necrosis indicating the cytotoxic nature of Kevlar fibres. 3. The third stage is dominated by the mesenchymal activation with capsular structures of collagenous fibres. Besides granulomatous foci, a slight submesothelial fibrosis is observed. 4. Fragments of Kevlar fibres are drained through lymphatic pathways and stored in lymph nodes where they lead to inflammatory reactions. 5. The reactive granulomatous changes in the greater omentum of rats are accompanied by proliferative mesothelial changes which, in one cases, even led to the development of a multilocular mesothelioma.

Rat models in peritoneal dialysis.

BACKGROUND: It is widely accepted that the currently used dialysis solutions are not biocompatible with the peritoneal membrane. Therefore, animal studies have been performed to study different aspects of peritoneal dialysis. However, representative models mimicking the human situation are not yet available. METHODS: The effect of a single injection of peritoneal dialysis (PD) fluid on the cellular composition was studied. Thereafter, the effect of a single injection of PD fluid on bacterial clearing was tested over time. Finally, an in vivo rat model was established to study the effects of long-term exposure to PD fluid on the peritoneal membrane and the local host defence (peritoneal cells). RESULTS: In the rat model, long-term daily exposure is possible. The 'drop-out' after 9-10 weeks on the most commonly used PD fluid Dianeal 3.86%, however, is approximately 50% due to omental wrapping. In the remaining study group, large differences were observed (as compared with controls), especially with respect to morphological parameters. CONCLUSIONS: The rat peritoneal continuous exposure model seems to have potential for intervention studies, since it uses no additions, no antibiotics and no omentomectomy, and gives continuous long-term exposure to PD fluid. However, problems still remain: 'drop-out' is quite often seen and this non-uraemic exposure model does not totally mimic the situation present in continuous ambulatory PD patients.