Browsing by Author "CHANDA, J"

Now showing 1 - 5 of 5
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    ANTICALCIFICATION TREATMENT OF PERICARDIAL PROSTHESES
    (BIOMATERIALS, 1994)
    The aim of the present study was to:develop a chemical treatment to eliminate highly antigenic substances, to standardize the glutaraldehyde fixation procedure, to determine the dominant factors contributing to the calcification process and to understand the role of macromolecules like chitosan in the prevention of calcification of bioprosthetic heart valves. Bovine pericardium treated with 5% sodium chloride-trypsin-glutaraldehyde (GA)-chitosan did not calcify at 12 wk in the rat (calcium, 1.1 +/- 0.27 mg/g; von Kossa, O), Slow release of residual GA from the bioprosthesis and free aldehyde groups on that are still considered the dominant factors for enhancing calcification of GA-treated bioprostheses.
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    POSTTREATMENT WITH AMINO-COMPOUNDS EFFECTIVE IN PREVENTION OF CALCIFICATION OF GLUTARALDEHYDE TREATED PERICARDIUM
    (ARTIFICIAL ORGANS, 1994)
    An attempt has been made to compare the role of different amino compounds in prevention of calcification of glutaraldehyde (GA)-treated pericardium implanted subcutaneously in the rat for 12 weeks. GA pretreated pericardial samples were postfixed separately with glycine, albumin, gentamicin, glycine + gentamicin, and albumin + gentamicin. Severe calcification was noticed in animals undergoing albumin or gentamicin post-fixation. Mild calcification was observed in glycine and albumin + gentamicin postfixed materials whereas calcium was undetectable either chemically or morphologically in GA-pretreated pericardium postfixed with glycine + gentamicin (0.32 +/- 0.13 mg/g calcium, dry wt; von Kossa 0) at the 12th week of implantation in the rat.
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    PREVENTION OF CALCIFICATION OF HEART-VALVE BIOPROSTHESES - AN EXPERIMENTAL-STUDY IN RAT
    (ANNALS OF THORACIC SURGERY, 1995)
    To eliminate highly antigenic substances, bovine pericardium was washed in 5% sodium chloride (NaCl) for 24 hours, followed by incubation in trypsin for 40 minutes. To achieve adequate fixation, NaCl-trypsin-treated pericardium was preserved in glutaraldehyde (GA) solution with gradually increasing concentrations from 0.1% to 0.25%. To inactivate the free aldehyde groups and residual GA on the surface of the implant, NaCl-trypsin-GA-treated pericardial samples were posttreated separately with 1% lysine, 8% monosodium glutamate, and 4% chitosan. Fresh (untreated) and 0.1%, 0.2%, and 0.625% GA-treated and NaCl-trypsin-GA-treated pericardial specimens were prepared for comparative study. All samples were implanted subdermally in rats for 2, 4, 8, and 12 weeks for calcification studies. Morphologic and chemical analyses showed mild calcification in fresh pericardia (Ca, 10.5 +/- 1.25 mu g/mg, von Kossa +) and in glutamate-posttreated pericardia (Ca, 11.5 a 3.45 mu g/mg, von Kossa +). Calcium was practically undetectable in chitosan-posttreated implants (Ca, 1.1 +/- 0.27 mu g/mg, von Kossa 0), whereas severe calcification was noticed in the rest of the samples (mean Ca greater than 200.0 mu g/mg, von Kossa +++) at 12 weeks. This study suggests that posttreatment with an amino compound such as chitosan would prevent the calcification of GA-treated bioprostheses at an early implantation stage, but elimination of antigenic factors and adequate GA fixation would prevent tissue degeneration, thus enabling the prosthesis to function over a long period.
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    PREVENTION OF CALCIFICATION OF TISSUE VALVES
    (ARTIFICIAL ORGANS, 1994)
    In this study an attempt was made to find an optimum method of chemical treatment to prevent the calcification of bioprosthetic heart valves. Bovine pericardium was washed in a 5% sodium chloride solution followed by trypsin (Tr) treatment and was kept in 0.1% glutaraldehyde (GA) with a gradual increase in concentration up to 0.25% GA and finally posttreated with a 4% chitosan (Ch) solution. Fresh, 0.2% GA, 0.625% GA, and sodium chloride-Tr-GA treated pericardial samples were taken for comparative study. Tensile testing showed comparable strength and elongation at the breaking point for all groups. The thermal shrinkage studies indicated merit of the proposed treatment (5% sodium chloride-trypsin-glutaraldehyde treated pericardia with chitosan and without chitosan posttreatment). Collagenase assay showed that all differently treated (GA) materials were equally resistant to collagenase. All samples were implanted subcutaneously in rats for 2, 4, 8, or 12 weeks for calcification study. Morphological and mineral analyses showed complete prevention of calcification in sodium chloridetrypsin-GA-chitosan treated pericardium (Ca was 1.1 +/- 0.27 mg/g, von Kossa 0) at the 12th week of implantation.
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    USE OF GLUTARALDEHYDE-GENTAMICIN-TREATED BOVINE PERICARDIUM AS A WOUND DRESSING
    (BIOMATERIALS, 1994) CHANDA, J; RAO, SB; MOHANTY, M; Muraleedharan, CV; ARTHUR, VL; BHUVANESHWAR, GS; VALIATHAN, MS
    Glutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 x 4cm, each of full thickness skin, from the upper and lower parts down to, but not including, the panniculus carnosus were made from the back of the guinea pig. The skin excised from the upper part was placed on the wound bed of the lower part as an autograft, whereas the upper wound was closed using 5% sodium chloride-trypsin-0.1% GA-0.048% gentamicin-treated bovine percardium and sutured for comparative study. The wounds were inspected every 3-6 d for infection and exudation. Histopathological studies were performed at weekly intervals in the post-operative period. At the fifth week, a very thin linear scar on the epidermal aspect without remarkable contracture was observed and histopathology showed the completion of epithelization across the wounds in all cases. This study demonstrates that GA-pretreated, gentamicin-post-fixed bovine pericardium may be used as an alternative biological dressing in the case of large wounds.