Thrombogenic effects of a nonthrombin-based fibrin sealant compared with thrombin-based fibrin sealant on microvenous anastomoses in a rat model.

The efficacy and safety of tissue adhesives needs to be clearly defined. A thrombin-based preparation of fibrin sealant has recently been shown to have deleterious effects on microvascular anastomoses in an animal model. The authors found that fibrin sealant constructed with a high concentration of bovine thrombin (1,000 IU per milliliter) was detrimental to microvascular patency when applied to the anastomosis in a rat free flap model. The microvenous anastomosis had the highest rate of thrombosis and failure in this model. A nonthrombin-based fibrin sealant has recently become available for experimental investigation. This study examined the thrombogenic effect of this nonthrombin-based fibrin sealant on microvenous anastomoses in a rat free flap model compared with the effect of traditionally prepared fibrin sealant with varying concentrations of thrombin. The conclusions reveal that flap survival with application of the nonthrombin-based fibrin sealant to the anastomosis was comparable with flap survival of the control animals. Flap survival with application of the traditionally prepared thrombin-based fibrin sealant was also comparable with flap survival of the control animals when a concentration of 500 IU per milliliter of thrombin was used. However, flap survival decreased significantly (p <0.005) when a concentration of 1,000 IU per milliliter of thrombin was used in the construct of the fibrin adhesive. These results support the previous findings of the harmful effects of thrombin when used in high concentrations and applied to the microvenous anastomosis of this free flap model. Moreover, this initial investigation with a nonthrombin-based fibrin sealant did not show any deleterious effects on the microvenous anastomosis compared with control animals.

Increased abundance of terrestrial isopod populations in terrestrial ecosystems contaminated with petrochemical wastes.

Arthropods are integral components of the food chain, and because many reside in close association to the soil and its contaminants, their communities may be sensitive indicators of ecotoxicity. We examined the influence of petrochemical contaminants on the abundance of several taxonomic groups of macroarthropods, with an emphasis on isopods, residing on two reference sites and three petrochemical-contaminated sites at an abandoned oil refinery site in southwestern Oklahoma. Relative densities of surface-dwelling macroarthropod assemblages were significantly greater on contaminated sites than reference sites. Differences in terrestrial isopod populations were particularly remarkable and consistent across study sites, with densities approaching 180-fold greater on contaminated than reference sites. Similarity comparisons indicated that abundances and composition of macroarthropod assemblages sampled on the contaminated sites were more similar to one another than to the communities residing on reference sites. Although preliminary, these initial results support the hypothesis that macroarthropod assemblages, in particular isopods, are sensitive to soil contaminants and could be a valuable approach to evaluating the effects of petrochemical contamination of soils on terrestrial ecosystems.

Ecotoxicity revealed in parasite communities of Sigmodon hispidus in terrestrial environments contaminated with petrochemicals.

Several studies have documented contaminant-induced alterations in host-parasite relationships of vertebrate hosts in aquatic environments, suggesting this functional relationship may be useful for monitoring community-level effects of stressors in terrestrial systems. We hypothesized that gastrointestinal helminth communities of hispid cotton rat (Sigmodon hispidus) hosts would be sensitive to exposure to complex mixtures of petrochemicals in soils of tallgrass prairie habitats contaminated with oil refinery wastes. Parasite communities were surveyed (1993-95) on three contaminated and two reference sites on an oil refinery complex in Oklahoma. Abundance of Schizotaenia sigmodontis infections was two-fold higher in hosts from reference than contaminated sites. Strongyloides sigmodontis exhibited pronounced seasonal differences in prevalence and abundance in host populations from reference sites, with much higher seasonal variation compared to hosts from contaminated sites. Other helminth species, including Schizotaenia sigmodontis, Protospirura muris, Longistriata adunca, also exhibited seasonal fluctuations in abundance. Differences in species richness and composition were also observed, with hosts from the reference sites consistently supporting a higher mean number of species compared to those from contaminated sites. Differences in community structure indicate that host-parasite relationships can provide another useful method for monitoring community-level impacts of contamination in a terrestrial system.

Evaluation of the developmental toxicity of caffeine and caffeine metabolites using the frog embryo teratogenesis assay--Xenopus (FETAX).

The developmental toxicities of caffeine and 13 metabolites, including theophylline, and paraxanthine and a synthetic methylxanthine analogue 3-isobutyl-methylxanthine (IBMX) were evaluated using the Frog Embryo Teratogenesis Assay Xenopus (FETAX). Young X. laevis embryos were exposed to these compounds in each of two separate concentration-response experiments with and without an exogenous metabolic activation system (MAS). Results obtained from these studies indicated that relative teratogenic potencies of caffeine and each of its di- and monomethylxanthine metabolites were similar. Representatives of both the substituted uric and uracil metabolites were less developmentally toxic on an equimolar basis than the methylxanthines, suggesting that they may have represented detoxification metabolites. IBMX, a phosphodiesterase inhibitor also known to be an adenosine receptor antagonist, was the most potent developmental toxicant of the materials evaluated. In conclusion, none of the caffeine metabolites tested was found to be significantly more potent than caffeine itself in the FETAX assay.

Molten metal burns: further evidence of industrial foundries' failure to comply with Occupational Safety and Health Administration regulations.

The purpose of this report is to describe another case of a molten metal burn to the foot of a foundry worker. The foundry in which he worked failed to comply with Occupational Safety and Health Administration regulations with regard to protective apparel. This injury could have been prevented with annual, unscheduled inspections by the Occupational Safety and Health Administration and with enforcement of additional regulations regarding protective apparel.

Search for a scientific basis for continuous suture closure: a 30-yr odyssey.

Continuous percutaneous and dermal suture closures have an important role in the approximation of long, linear lacerations in the emergency department. This report documents the scientific basis for these continuous closure techniques. In addition, a detailed description of these surgical closure techniques is presented.

Technical considerations in knot construction. Part II. Interrupted dermal suture closure.

The purpose of this study was to identify the optimal knot construction for interrupted dermal sutures. A synthetic braided absorbable suture, sizes 3-0 and 5-0, was selected for this evaluation. With reproducible mechanical performance tests, we determined that the construction of secure knots without ears required one additional throw as compared with secure knots with 3-mm ears. The direction of applied tension did not alter knot security, with the exception of granny knots, which required an extra throw when tension was applied parallel to the suture loop. Because interrupted dermal knot construction is accomplished without knot ears and with an applied tension parallel to the wound, one additional throw must be added to the knot to ensure knot security.

A new stable pluronic F68 gel carrier for antibiotics in contaminated wound treatment.

Pluronic F68 was selected as the gel carrier for antimicrobial agents because of its extensive use as a wound cleanser in humans without discernable side effects. When the concentration of this surfactant is increased to 46%, it forms a water soluble gel that can serve as a carrier for antimicrobial agents. The stability of this gel can be enhanced by immediately cooling (-15 degrees C) the gel for 24 hours before storage and subsequent application. Immediate cooling of the gel causes hydration of the surfactant that is associated with gel strengthening and prolonged shelf life stability. In experimental animals, this stable gel carrier containing 0.2% nitrofurazone significantly reduces the bacterial concentration of Staphylococcus aureus in wounds to a greater degree than silver sulfadiazine. This antimicrobial gel has the same antimicrobial activity as polyethylene glycol carriers containing 0.2% nitrofurazone, but does not carry the potential risk of polyethylene glycol intoxication.

Knot performance of polypropylene sutures.

A mechanical performance test using an Instron Tensile Tester demonstrated the superior handling characteristics of Surgipro suture as compared to Prolene suture that facilitated knot construction without suture breakage. For both granny and square knots, the knot run down forces for the Surgipro sutures were significantly less than those encountered for comparable knots for Prolene sutures. This propensity of the two-throw knots of Surgipro sutures to advance without breakage considerably facilitated knot construction.

Biomechanical and clinical performance of a new synthetic monofilament absorbable suture.

The clinical and mechanical performance of a new, monofilament, synthetic absorbable suture (Biosyn) was evaluated and compared to that of a braided synthetic absorbable suture (Vicryl). The monofilament synthetic absorbable suture was significantly stronger than the braided synthetic absorbable suture over the 4 weeks of implantation. In addition, the monofilament suture potentiated less bacterial infection than did the braided suture. The handling characteristics of the monofilament suture were superior to the braided suture because the monofilament suture required fewer throws to achieve knot security, encountered lower drag forces in fascia and colon, and had a greater double-wrapped first-throw knot security. Evaluated independently in clinical settings, the monofilament sutures were found to have excellent strength, first-throw hold, knot security, passage through tissue, knot repositioning, and ease of handling.

Biomechanical performance of a braided absorbable suture.

Lactomer and Polyglactin 910 sutures are both made of copolymers of lactide and glycolide. Biomechanical performance tests demonstrated superior handling characteristics of the Lactomer sutures. Using sutures comparable in size and knot construction, the Lactomer sutures exhibited knot holding force superior to the Polyglactin 910. Moreover, the low knot rundown forces encountered by the Lactomer sutures facilitated construction of secure knots that failed by breakage rather than by slippage.

Influence of Biobrane construction on adherence.

Biobrane (standard adherence) and Biobrane L (light adherence) were compared for their degree of adherence to donor site wounds on rabbits at 1, 4, 7, and 9 days. Biobrane, which has more nylon fabric exposed to the wound surface, had significantly greater adherence levels to the wound at all time periods when compared with Biobrane L, which has less nylon fabric exposed to the wound.

Wound cleansing by irrigation for implant surgery.

Wound irrigation is an adjunct to all implant surgeries involving surgical incisions or arthroplasties. An understanding of the physics of wound irrigation provides a scientific basis for recommending wound irrigation systems for implant surgery. When inserting implants through surgical incisions, a low-pressure irrigation system is recommended for removing blood from the wound surface. In contrast, high-pressure irrigation systems are indicated to cleanse the intramedullary canal before cemented arthroplasty. With the advent of static and dynamic pressure transducers, irrigation systems can now be specifically designed to achieve these goals.