Biomedical subjects

R Tu

Publications and source records attributed to R Tu.

40 records · Page 3Linked to original sources

PubMedDate not supplied

Mucoepidermoid tracheal adenoma during pregnancy.

A 30-year-old, 36-week pregnant, female was admitted to the hospital with progressive "asthma" and wheezing. She was markedly dyspneic and unable to lie down or to sleep for periods over an hour. Bronchoscopy demonstrated an endobronchial tumor just above the carina. Following ventilating tracheal bronchoscopy with dilatation of the trachea and establishment of an airway through the tumor, a cesarean section was performed with resultant delivery of a healthy, female, infant. A partial abruptio placentae was noted. Under the same anesthetic, a right posterior lateral thoracotomy with resection of the tracheal tumor was performed. Preoperative and operative considerations are described.

Adenoma↗

PubMedDate not supplied

A newly developed porcine heart valve bioprosthesis fixed with an epoxy compound. An experimental evaluation.

Concerns with currently available bioprostheses are calcification, long-term durability, and functional and hemodynamic performance. It has been well known that these concerns are all more or less related to the fixatives, glutaraldehyde or formaldehyde, used in preserving bioprostheses. To address these concerns, we undertook the development of a porcine bioprosthesis fixed with an epoxy compound. It was discovered that the porcine leaflets fixed with the epoxy compound appeared more natural than those preserved with glutaraldehyde. The performance of this newly developed epoxy compound bioprosthesis (three samples) was evaluated in a juvenile sheep model. The results were compared to those of its glutaraldehyde counterpart (three samples). Two-dimensional echocardiographic inspection of the valvular leaflet motion indicated that the epoxy compound leaflets were more pliable than their glutaraldehyde counterparts. In addition, the epoxy compound valve appeared to open more widely than the glutaraldehyde valve. Color Doppler flow mapping demonstrated that the blood flow distal to the epoxy compound valve was slightly broader than that observed distal to the glutaraldehyde valve. Moreover, at retrieval, less calcium and pannus ingrowth were observed in the epoxy compound valve than its glutaraldehyde counterpart. The results of this preliminary evaluation indicated that the performance of this newly developed epoxy compound valve was at least equivalent to its glutaraldehyde counterpart, if not better.

Animals↗

PubMedDate not supplied

Comparison of the cross-linking characteristics of porcine heart valves fixed with glutaraldehyde or epoxy compounds.

The concerns about currently available bioprosthetic heart valves are calcification, long-term durability, and functional and hemodynamic performance. These concerns are all more or less related to the cross-linking reagents, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, the authors undertook the development of a porcine heart valve cross-linked with an epoxy compound. This study compared the cross-linking characteristics, shrink temperature, and moisture content of porcine heart valves fixed with epoxy compounds or glutaraldehyde. Two types of epoxy compounds, Denacol EX-313 and EX-810, or a 0.625% glutaraldehyde were used to fix the porcine aortic valves procured from a slaughter house. Samples of each group were removed at various elapsed fixation times. The shrink temperature and moisture content of the valvular leaflet and distinct layers of aortic wall of each sample were measured. Fresh porcine aortic valve was used as a control. It was found that the shrink temperature of the glutaraldehyde leaflet was the highest, whereas the moisture content of the EX-313 leaflet was the greatest among the three test groups. No significant difference in shrink temperature was observed among the epoxy compound fixed inner, middle, outer, and entire aortic walls. This implied that the cross-linking density of the epoxy compound valve was uniform throughout the entire aortic wall. The same also was observed for the glutaraldehyde fixed aortic wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Evaluation of epoxy ether fixed bovine arterial grafts for mutagenic potential.

Two epoxy ether compounds [glycerol polyglycidyl ether (Denacol EX-313) and ethylene glycol diglycidyl ether (Denacol EX-810)] are under consideration as alternatives to glutaraldehyde for use in the processing of an arterial graft. The two are utilized as cross-linking and sterilant agents, respectively. Epoxy resins are multifunctional alkylating agents, and bifunctional alkylating epoxide solutions are known to be mutagenic. The correlation between mutagenic potential and carcinogenicity, in addition to evidence that diepoxides are carcinogenic in mice and rats, prompted the evaluation of the mutagenic potential of the epoxy treated, clinically rinsed graft. Ames and sister chromatid exchange (SCE) test procedures were used to assess mutagenic potential. Normal saline and distilled water were selected as the most physiologically representative and procedurally acceptable extraction mediums for the Ames and SCE tests, respectively. The results of the Ames and SCE tests in both the activated and non activated systems indicated that there were no statistically significant differences detected between various test article concentrates and the spontaneous mutation controls for both the activated and non activated systems. The epoxy treated graft was determined to be non mutagenic and demonstrated no dose related responses by these methods.

Animals↗