Crosslinking characteristics and mechanical properties of a bovine pericardium fixed with a naturally occurring crosslinking agent.

Currently available crosslinking agents used in fixing bioprostheses are all highly (or relatively highly) cytotoxic, which may induce an adverse inflammatory reaction in vivo. It is therefore desirable to provide a crosslinking agent that is of low cytotoxicty and may form stable and biocompatible crosslinked products. To achieve this goal, a naturally occurring crosslinking agent-genipin-was used by our group to fix biological tissues. Genipin may be obtained from its parent compound, geniposide, which may be isolated from the fruits of Gardenia jasminoides Ellis. In our previous studies, it was found that the cytotoxicity of genipin is significantly lower than both glutaraldehyde and an epoxy compound. Also, it was shown that genipin can form stable and biocompatible crosslinked products. The present study further investigates the crosslinking characteristics and mechanical properties of a genipin-fixed bovine pericardium. Fresh and glutaraldehyde- and epoxy-fixed counterparts were used as controls. It was found that the denaturation temperatures of the glutaraldehyde- and genipin-fixed tissues were significantly greater than the epoxy-fixed tissue, although their fixation indices were comparable. The mechanical properties of fresh bovine pericardium are anisotropic. However, fixation tended to eliminate tissue anisotropy. The tendency in the elimination of tissue anisotropy for the genipin-fixed tissue was more remarkable than for the glutaraldehyde- and epoxy-fixed tissues. In addition, the genipin-fixed tissue had the greatest ultimate tensile strength and toughness among all the fixed tissues. Distinct patterns in rupture were observed in the study: The torn collagen fibers of the genipin- and glutaraldehyde-fixed tissues appeared to be bound together, while those of fresh and the epoxy-fixed tissues stayed loose. The results obtained in the study suggests that tissue fixation in glutaraldehyde, epoxy compound, and genipin may produce distinct crosslinking structures. The differences in crosslinking structure may affect the crosslinking characteristics and mechanical properties of the fixed tissues.

Comparison of P6 acupoint injection with 50% glucose in water and intravenous droperidol for prevention of vomiting after gynecological laparoscopy.

Postoperative vomiting causes patients distress and delays discharge after outpatient surgery. Although P6 electroacupuncture is recognized as having an antiemetic effect, its inconvenient instrumentation may limit its clinical applicability. The purpose of this study was to explore a simple and effective alternative method for control of postoperative vomiting in outpatient surgery. We prospectively compared the effect of P6 acupoint injection with 0.2 ml 50% glucose in water (G/W) and intravenous injection of 20 micrograms/kg droperidol for prevention of vomiting in 120 consecutive outpatients undergoing gynecological laparoscopy with general anesthesia. Patients were randomly allocated to receive P6 acupoint injection, i.v. droperidol, or nothing as control group. Both P6 acupoint injection and i.v. droperidol 20 micrograms/kg were found to have a significant antiemetic effect when compared with the control group. We conclude that P6 acupoint injection with 50% G/W is a simple and effective method for reducing the incidence of postoperative emesis in outpatient surgery.

Noninvasive temperature imaging using diffusion MRI.

Efficacy and safety considerations for cancer therapy with hyperthermia require accurate temperature measurements throughout the heated volume. We report the use of molecular diffusion, whose temperature dependence is well known. A dedicated hyperthermia applicator was built, combining a MRI gradient coil and a rf coil. Diffusion and derived temperature images were obtained with a 1 x 2 mm pixel size on a polyacrylamide gel phantom using a clinical 1.5-T whole body MRI system. Temperatures determined from these images using 1 cm2 regions of interest were found to be within 0.2 degrees C of those recorded from the thermocouples and fiber-optic probes placed inside the gel.