M Mohanty

Publications of M Mohanty

• Evaluation of an in situ forming hydrogel wound dressing based on oxidized alginate and gelatin.

  Authors: Biji Balakrishnan, M Mohanty, P R Umashankar, A Jayakrishnan

  Biomaterials. 12/2005; 26(32):6335-42.

  Wound dressings that can be formed in situ offer several advantages over the use of preformed dressings such as conformability without wrinkling or fluting in the wound bed, ease of application andWound dressings that can be formed in situ offer several advantages over the use of preformed dressings such as conformability without wrinkling or fluting in the wound bed, ease of application and improved patient compliance and comfort. Here we describe such an in situ forming hydrogel wound dressing from gelatin, oxidized alginate and borax. Periodate oxidized alginate rapidly cross-links proteins such as gelatin in the presence of borax to give in situ forming hydrogels that are both non-toxic and biodegradable. The composite matrix has the haemostatic effect of gelatin, the wound healing-promoting feature of alginate and the antiseptic property of borax to make it a potential wound dressing material. The hydrogel was found to have a fluid uptake of 90% of its weight which would prevent the wound bed from accumulation of exudates. The water vapour transmission rate (WVTR) of the hydrogel was found to be 2686+/-124 g/m2/day indicating that the hydrogel can maintain a moist environment over wound bed in moderate to heavily exuding wound which would enhance epithelial cell migration during the healing process. The wound healing efficacy of hydrogel was evaluated in experimental full thickness wounds using a rat model which demonstrated that within 2 weeks, the wound covered with gel was completely filled with new epithelium without any significant adverse reactions. These in situ forming hydrogels fulfil many critical elements desirable in a wound dressing material.

• Long term tissue response to titanium coated with diamond like carbon.

  Authors: M Mohanty, T V Anilkumar, P V Mohanan, C V Muraleedharan, G S Bhuvaneshwar, F Derangere, Y Sampeur, R Suryanarayanan

  Biomolecular engineering. 09/2002; 19(2-6):125-8.

  Diamond like carbon (DLC) coatings were deposited on to Ti substrates by plasma enhanced chemical vapor deposition technique. Ti and DLC/Ti samples were implanted in skeletal muscle of rabbits. TheDiamond like carbon (DLC) coatings were deposited on to Ti substrates by plasma enhanced chemical vapor deposition technique. Ti and DLC/Ti samples were implanted in skeletal muscle of rabbits. The samples were explanted after 1, 3, 6 and 12 months and the tissue-cell interaction was studied. Our data indicate both DLC/Ti and bare Ti to be compatible with skeletal muscle.

• The influence of photodynamic therapy on the wound healing process in rats.

  Authors: R S Jayasree, A K Gupta, K Rathinam, P V Mohanan, M Mohanty

  Journal of biomaterials applications. 02/2001; 15(3):176-86.

  In photodynamic therapy (PDT), photosensitisers (PS) are used along with lasers for the treatment of tumors. The combined effect of photosensitisers and lasers on the wound healing process is studiedIn photodynamic therapy (PDT), photosensitisers (PS) are used along with lasers for the treatment of tumors. The combined effect of photosensitisers and lasers on the wound healing process is studied using delta-aminolevulinic acid (ALA) (5 mg/kg) and hematoporphyrin derivative (HPD) (5 mg/kg) as photosensitisers in the open excision wounds of rats. The lasers used were He-Ne laser (3 J/cm2) and Nd:YAG laser (30 J/cm2). This study is important for understanding the healing process involved after PDT. Open excision wounds treated with He-Ne lasers in animals that received ALA as photosensitiser showed complete wound closure at the earliest by 13 +/- 1 days, and with results obtained for HPD and the combination of lasers with complete closing by 14 +/- 1 days. However, the control group of animals that received ALS or HPD with no laser treatment showed wound healing on the twentieth and eighteenth days with a deviation of one day and two days, respectively. ALA with the combination of Nd:YAG and He-Ne lasers and HPD with He-Ne laser alone does not show quicker wound healing effects. Histopathological results also gave similar results. Tensile strength measurements do not vary significantly from control group to the test group. ALA along with He-Ne laser of HPD along with the combination of He-Ne and low power Nd-YAG lasers are found to be ideal methods for quickening the wound healing process in rat.

• Synergistic effect of released aspirin/heparin for preventing bovine pericardial calcification.

  Authors: S C Vasudev, T Chandy, C P Sharma, M Mohanty, P R Umasankar

  Artificial organs. 03/2000; 24(2):129-36.

  Calcification is a frequent cause of the clinical failure of bioprosthetic heart valves fabricated from glutaraldehyde pretreated bovine pericardium (GATBP). Aspirin, a potent antiplatelet drug, andCalcification is a frequent cause of the clinical failure of bioprosthetic heart valves fabricated from glutaraldehyde pretreated bovine pericardium (GATBP). Aspirin, a potent antiplatelet drug, and heparin, an anticoagulant, are commonly used for postimplant complications such as thrombosis and thromboembolism. Aspirin and heparin were embedded in chitosan/polyethylene vinylacetate co-matrix to develop a prolonged release form. The effect of these drugs towards the bioprosthetic calcification was investigated by in vitro and in vivo models. In vitro and in vivo evaluation suggest that the released aspirin/heparin from the co-matrix had a synergistic effect in inhibiting GATBP calcification. In vivo subcutaneous co-implantation was performed with PEG-20,000 grafted bovine pericardium (PEG-GABP), aspirin, and heparin. Biochemical, histological, and scanning electron microscopic evaluation of retrieved samples demonstrated a significant reduction in calcium deposition and alkaline phosphatase activity on PEG-GABP compared to GATBP. It seems that the aspirin/heparin combination synergistically inhibits the pericardial calcification in addition to their antithrombotic function.

• Effects of double cross-linking technique on the enzymatic degradation and calcification of bovine pericardia.

  Authors: S C Vasudev, T Chandy, C P Sharma, M Mohanty, P R Umasankar

  Journal of biomaterials applications. 02/2000; 14(3):273-95.

  The strength, resorption rates, and biocompatibility of collagenous biomaterials are profoundly influenced by the method of cross-linking. The in vitro and in vivo calcification and enzymaticThe strength, resorption rates, and biocompatibility of collagenous biomaterials are profoundly influenced by the method of cross-linking. The in vitro and in vivo calcification and enzymatic degradation of bovine pericardia (BP) after a series of surface modifications were studied as a function of exposure time. Collagenase degradations of modified BP were monitored by scanning electron microscopy and tensile strength measurements. Bovine pericardium was modified by a combination of different tissue fixatives such as glutaraldehyde (GA), carbodiimide (EDC), diisocyanate (HMDIC), and polyethylene glycol (PEG). GA-PEG-EDC-PEG and GA-PEG-HMDIC-PEG combination treated BP retained maximum stability in collagenase digestion compared to GATBP. In vitro calcification studies and in vivo rat subcutaneous implantations of modified pericardium have shown substantial reduction in the calcification of double cross-linked BP with PEG modification. Further, the biocompatibility aspects of pericardial tissues were established by platelet adhesion and octane contact angle. It seems that cross-links involving amino and carboxyl residues may provide new ways of controlling biodegradation and calcification.

• Structural studies on bovine bioprosthetic tissues and their in vivo calcification: prevention via drug delivery.

  Authors: T Chandy, M Mohanty, A John, S B Rao, R Sivakumar, C P Sharma, M S Valiathan

  Biomaterials. 04/1996; 17(6):577-85.

  Cardiovascular calcification, the formation of calcium phosphate deposits in cardiovascular tissue, is a common end-stage phenomenon affecting a wide variety of bioprostheses. To study the process ofCardiovascular calcification, the formation of calcium phosphate deposits in cardiovascular tissue, is a common end-stage phenomenon affecting a wide variety of bioprostheses. To study the process of calcification in tissue prosthetics, glutaraldehyde-treated bovine pericardium, dura mater and fascialata were implanted subcutaneously in rats and retrieved 21 days later and thereby morphological findings were correlated with biochemically determined levels of calcium. Transmission electron microscopy showed that calcification primarily involved the surface of collagen fibrils and the interfibrillar spaces. The deposition of calcium was higher with dura and fascia prostheses compared to pericardium. However, the release of Fe3+ ions from chitosan matrix had substantially inhibited the deposits of calcium in all implanted tissues. It seems that the structural and anatomical features of the tissue is one of the important factors for tissue-associated calcification. It is also confirmed that glutaraldehyde-preserved pericardium is the most suitable material for the development of cardiac prosthesis, with an appropriate drug combination therapy for prevention of pathological calcification.

• Cellular basis for failure of joint prosthesis.

  Authors: M Mohanty

  Bio-medical materials and engineering. 02/1996; 6(3):165-72.

  In recent times, loosening of joint prosthesis resulting in failure, is of grave concern to orthopedicians. It is estimated that 50% of total hip replacements become loose after 15 years, and most ofIn recent times, loosening of joint prosthesis resulting in failure, is of grave concern to orthopedicians. It is estimated that 50% of total hip replacements become loose after 15 years, and most of them require either revision surgery or resection orthoplasty. Neither, newer operative techniques, change in design, use of novel materials, nor surface modifications have helped to circumvent the problem. It is in this context, that attention has been focussed on the role of tissue surrounding the implant, in the loosening of the prosthesis. Tissue response around prosthesis results in either formation of a fibrous layer around the implant, ingrowth into fenestrations on implant or direct bone apposition on prosthesis. Long-term implantation results in implant debris being released into surrounding tissue. These particles initiate a chronic granulonatous inflammation with a significant number of activated macrophages and foreign body type of giant cells, all engaged in attempts to get rid of the debris. These features have been found to be invariably associated with peri-prosthetic lysis of bone. Since such bone resorption is also observed around non-cemented prosthesis, possibly causes other than cement are responsible for the osteolysis. Retrospective studies on failed implants suggest that peri-prosthetic osteolysis is mediated by activated macrophages. Cytokines are capable of stimulating bone resorbing cells, the osteoclasts. Bone resorption results in further loosening of the prosthesis, changes in stress, frictional wear, release of more wear debris and recruitment of more macrophages. Bone death and proliferation of macrophages, thus appear to be the cause for pain and loosening of prosthesis.

• Casein as a carrier matrix for 5-fluorouracil: drug release from microspheres, drug-protein conjugates and in-vivo degradation of microspheres in rat muscle.

  Authors: M S Latha, A Jayakrishnan, K Rathinam, M Mohanty

  The Journal of pharmacy and pharmacology. 12/1994; 46(11):858-62.

  Glutaraldehyde cross-linked casein microspheres were loaded with 5-fluorouracil (5-FU) from concentrated aqueous solutions of the drug after the microspheres were synthesized and cleaned. In-vitroGlutaraldehyde cross-linked casein microspheres were loaded with 5-fluorouracil (5-FU) from concentrated aqueous solutions of the drug after the microspheres were synthesized and cleaned. In-vitro release of the drug was examined in phosphate buffer in the absence and in the presence of protease at 37 degrees C. Drug release data showed that only about 20% of the drug is released in the absence of protease even after 5 days, while digestion of the matrix with protease released the entrapped drug completely in about 24 h. A protein-drug conjugate was synthesized via carbamoyl linkage using 6-(5-FU-1-yl)hexyl isocyanate and the drug release was examined in phosphate buffer at 37 degrees C. Release from the protein-5-FU conjugate was slower compared with the release from microspheres in the presence of protease. Implantation of placebo microspheres of different cross-linking densities in the gluteal muscle of rats showed no adverse tissue reactions over a one-year period. Histopathological examination of the tissues containing injected microspheres suggested that the biological life of casein microspheres in muscle is about 6 months, which is three times that of cross-linked albumin microspheres.

• Prevention of calcification of tissue valves.

  Authors: J Chanda, S B Rao, M Mohanty, A V Lal, C V Muraleedharan, G S Bhuvaneshwar, M S Valiathan

  Artificial organs. 11/1994; 18(10):752-7.

  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 chlorideIn 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 chloride-trypsin-GA-chitosan treated pericardium (Ca was 1.1 +/- 0.27 mg/g, von Kossa 0) at the 12th week of implantation.

• Use of glutaraldehyde-gentamicin-treated bovine pericardium as a wound dressing.

  Authors: J Chanda, S B Rao, M Mohanty, C V Muraleedharan, V L Arthur, G S Bhuvaneshwar, M S Valiathan

  Biomaterials. 02/1994; 15(1):68-70.

  Glutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 x 4 cm, each of full thickness skin, fromGlutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 x 4 cm, 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 pericardium 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.

• Evaluation of soft tissue response to a poly(urethane urea).

  Authors: M Mohanty, J A Hunt, P J Doherty, D Annis, D F Williams

  Biomaterials. 02/1992; 13(10):651-6.

  Variations in the performance of vascular prostheses constructed of polyurethanes, and some evidence which suggested that these variations could be due not to the properties of the polymer itself,Variations in the performance of vascular prostheses constructed of polyurethanes, and some evidence which suggested that these variations could be due not to the properties of the polymer itself, but to differences in the cellular response to the various microstructures of porous polyurethanes require investigation. Experiments were performed to evaluate quantitatively the extent of the cell behaviour adjacent to a series of polyurethane samples. It was shown that, with Biomer, a polyurethane urea, the profile of cell behaviour as a function of distance from the implant surface and of time following implantation, the response of cells in general and macrophages in particular, varied considerably with different internal microstructure. This supports the suggestion that the cellular response to different structures and susceptibility to degradation are related.

• Studies on the effect of degree of hydrophilicity on tissue response of polyurethane interpenetrating polymer networks.

  Authors: P D Nair, M Mohanty, K Rathinam, M Jayabalan, V N Krishnamurthy

  Biomaterials. 02/1992; 13(8):537-42.

  Interpenetrating polymer networks of polyurethane and vinyl monomers such as polyacrylamide, polyvinyl pyrrolidone, poly(hydroxyethyl methacrylate) and poly(methyl methacrylate) were implantedInterpenetrating polymer networks of polyurethane and vinyl monomers such as polyacrylamide, polyvinyl pyrrolidone, poly(hydroxyethyl methacrylate) and poly(methyl methacrylate) were implanted intramuscularly in rabbits. Attempts were made to correlate the morphological aspects of the interpenetrating polymer networks to their histological response. A relatively increased hydrophilicity of hydrophobicity of the interpenetrating polymer networks as in the case of polyurethane-polyvinyl pyrrolidone and polyurethane-poly(methyl methacrylate) interpenetrating polymer networks, respectively, could elicit an inert response whilst degradation of materials promoted reactivity.

• Chronic arterial occlusion in a canine model: a novel technique.

  Authors: K Ravimandalam, V R Rao, S Kumar, S Joseph, A V Lal, M Mohanty

  AJR. American journal of roentgenology. 01/1991; 155(6):1348.

• Preparation and evaluation of radiopaque hydrogel microspheres based on PHEMA/iothalamic acid and PHEMA/iopanoic acid as particulate emboli.

  Authors: A Jayakrishnan, B C Thanoo, K Rathinam, M Mohanty

  Journal of biomedical materials research. 09/1990; 24(8):993-1004.

  Highly porous poly(2-hydroxyethyl methacrylate) (PHEMA) microspheres prepared by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) in presence of polymeric diluents such as poly(methylHighly porous poly(2-hydroxyethyl methacrylate) (PHEMA) microspheres prepared by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) in presence of polymeric diluents such as poly(methyl methacrylate) (PMMA) in toluene and poly(tetramethylene glycol) (PTMG) were made radiopaque by esterification of the reactive hydroxyl groups with iothalamic acid and iopanoic acid, two radiopaque substances clinically used. Of the various solvents and catalysts examined, tetrahydrofuran (THF) and N,N'-dimethyl paratoluidine (DMPT) were found to be best for obtaining a high degree of conversion. More than 30 wt% iodine could be bound to the microspheres which made them sufficiently radiopaque to be imaged radiographically. Microspheres retained their porosity, swelling ability, hydrophilicity, and surface morphology to a significant extent after iodination. Preliminary implantation studies of such microspheres subcutaneously in rats have shown no adverse tissue reactions over a 6-month period. It is suggested that these microspheres would prove to be useful as particulate emboli in endovascular embolization.

• Prevention of calcification of tissue valves

  Authors: J Chanda, S B Rao, M Mohanty, A V Lal, CV Muraleedharan, GS Bhuvaneshwar, MS Valiathan

  Artificial organs. 18(10):752-757.

• Use of glutaraldehyde-gentamicin-treated bovine pericardium as a wound dressing

  Authors: J. Chanda, S.B. Rao, M. Mohanty, C.V. Muraleedharan, V.L. Arthur, G.S. Bhuvaneshwar, M.S. Valiathan

  Biomaterials.

  Glutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 × 4cm, each of full thickness skin, fromGlutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 × 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.

• Evaluation of an in situ forming hydrogel wound dressing based on oxidized alginate and gelatin

  Authors: Biji Balakrishnan, M. Mohanty, P.R. Umashankar, A. Jayakrishnan

  Biomaterials.

  Wound dressings that can be formed in situ offer several advantages over the use of preformed dressings such as conformability without wrinkling or fluting in the wound bed, ease of application andWound dressings that can be formed in situ offer several advantages over the use of preformed dressings such as conformability without wrinkling or fluting in the wound bed, ease of application and improved patient compliance and comfort. Here we describe such an in situ forming hydrogel wound dressing from gelatin, oxidized alginate and borax. Periodate oxidized alginate rapidly cross-links proteins such as gelatin in the presence of borax to give in situ forming hydrogels that are both non-toxic and biodegradable. The composite matrix has the haemostatic effect of gelatin, the wound healing-promoting feature of alginate and the antiseptic property of borax to make it a potential wound dressing material. The hydrogel was found to have a fluid uptake of 90% of its weight which would prevent the wound bed from accumulation of exudates. The water vapour transmission rate (WVTR) of the hydrogel was found to be 2686±124 g/m2/day indicating that the hydrogel can maintain a moist environment over wound bed in moderate to heavily exuding wound which would enhance epithelial cell migration during the healing process. The wound healing efficacy of hydrogel was evaluated in experimental full thickness wounds using a rat model which demonstrated that within 2 weeks, the wound covered with gel was completely filled with new epithelium without any significant adverse reactions. These in situ forming hydrogels fulfil many critical elements desirable in a wound dressing material.