Browsing by Author "Bhuvaneshwar, GS"

Now showing 1 - 17 of 17
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    Chitra heart valve: Results of a multicenter clinical study
    (JOURNAL OF HEART VALVE DISEASE, 2001)
    Background and aim of the study: The Chitra tilting disc valve was developed in India to meet the need for a low-cost cardiac valve. The valve has an integrally machined cobalt-based alloy cage, an ultrahigh molecular-weight polyethylene disc, and a polyester suture ring. An important feature of this valve is its soft closing sound, by virtue of a plastic occluder.Methods: Between December 1990 and January 1995, 306 patients underwent isolated aortic MR, n = 101) or mitral valve replacement (MVR, n = 205) at six institutions in India. The early mortality rate was 6.9% (seven after AVR; 14 after MVR). A total of 285 survivors was followed up until September 1998; total follow up was 1212 patient-years (pt-yr) (AVR, 445 pt-yr; MVR, 767 pt-yr).Results: There were 52 late deaths (4.3%/pt-yr; AVR 2.2%/pt-yr; MVR 5.5%/pt-yr). Thirty-five deaths were valve-related (23 were due to unknown causes). One AVR patient (0.2%/pt-yr) and 12 MVR patients (1.6%/pt-yr) developed valve thrombosis, and embolic episodes occurred in 25 patients (seven after AVR, 1.6%/pt-yr; 18 after MVR, 2.4%/pt-yr). Bleeding events and infectious endocarditis occurred infrequently (AVR 0.9 and 0.7%/pt-yr; MVR 0.4 and 0.5%/pt-yr, respectively). There was no incidence of paravalvular leak or structural dysfunction of the valve. Actuarial survival rates at seven. years were 82.4 +/- 4.0% for AVR and 65.2 +/- 5.0% for MVR. During the same interval, thrombus-free and embolism-free survival after AVR and MVR occurred in 98.9 +/- 1.1% and 94.1 +/- 1.9%, and 92.3 +/- 2.8% and 82.1 +/- 5.7% of patients, respectively. Freedom from all valve-related mortality and morbidity at seven years was 81.5 +/- 4.1% after AVR, and 64.2 +/- 5.1% after MVR.Conclusion: The Chitra valve appears to be safe and to have performance comparable with that of other currently used tilting disc valves. This valve costs substantially less than other valves, and is therefore within reach of a larger subset of Indian patients.
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    Development of an in-vitro Pyrogen test kit: Evaluation of pyrogenicity using human whole blood ( Project - 7030 )
    (SCTIMST, 2006-06-30) Mohanan, PV; Lissy K, Krishnan; Muraleedharan, CV; Bhuvaneshwar, GS
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    Development of National GLP Guidelines & Identification and selection of National Regulatory Guidelines for Testing and Evaluation of Medical Devices ( Project - 8027 )
    (SCTIMST, 2022-03-31) Mohanan, PV; Muraleedharan, CV; Nagesh, DS; Maya Nandakumar, A; Lissy K, Krishnan; Kumary, TV; Mira, Mohanty; Sreenivasan, K; Bhuvaneshwar, GS
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    Development of the chitra tilting disc heart valve prosthesis
    (JOURNAL OF HEART VALVE DISEASE, 1996) Bhuvaneshwar, GS; Muraleedharan, CV; Vijayan, GA; Kumar, RS; Valiathan, MS
    Background nun aims of the study: The high prevalence of rheumatic valvular disease in the young population and the high cost of imports necessitated the development of an Indian valve. The development of a tilting disc prosthesis was successfully concluded in February 1995, when the third model completed its clinical trial. The tilting disc valve has an integrally machined cobalt alloy cage, an ultra high molecular weight polyethylene disc and a polyester suture ring. The choice of design was based on its superior hydrodynamics and the age distribution of patients, the majority of whom were below 30 years. The polymer-metal combination was selected for its extremely low wear rate and proven durability in the human body. Materials and methods: The hydrodynamic performance was tested under steady and pulsatile flow conditions. The accelerated durability of nine test valves was evaluated at 800-840 cycles/min for over 350 million cycles each. Size 23mm valves mere implanted in the mitral position of five sheep. In a clinical trial, 306 patients with isolated mitral or aortic valve replacements were followed up for a total of 371 patient years (mean 1.37 years and range 0-4 years). Results: The hydrodynamic performance was comparable to that of proven clinical models. The accelerated testing indicated lifetimes in excess of 50 years and the animal trials showed the valve to be safe. In the clinical trial, there was no incidence of structural failure or paravalvular leak. The linearized rate of late thromboembolism was 6.2 %/patient-year (pty), anticoagulant related hemorrhage 0.54 %/pty and infective endocarditis 0.54 %/pty. At two years, the total actuarial survival was 89.5%. The higher incidence of thromboembolism and the very low incidence of anticoagulant related hemorrhage illustrate the difficulty in the management of anticoagulant therapy in a developing country, while the low incidence of endocarditis reflects their greater resistance to infection. Conclusion: These data clearly showed the valve to be safe and comparable to other similar valves in clinical use.
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    Developments in mechanical heart valve prosthesis
    (SADHANA-ACADEMY PROCEEDINGS IN ENGINEERING SCIENCES, 2003) Nair, K; Muraleedharan, CV; Bhuvaneshwar, GS
    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the performance of mechanical heart valves. The clinical performance of mechanical heart valves is also addressed. Efforts made in India in the development of mechanical heart valves are also discussed.
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    Engineering of a polymer layered bio-hybrid heart valve scaffold
    (MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS, 2015) Jahnavi, S; Kumary, TV; Bhuvaneshwar, GS; Natarajan, TS; Verma, RS
    Current treatment strategy for end stage valve disease involves either valvular repair or replacement with homograft/mechanical/bioprosthetic valves. In cases of recurrent stenosis/ regurgitation, valve replacement is preferred choice of treatment over valvular repair. Currently available mechanical valves primarily provide durability whereas bioprosthetic valves have superior tissue compatibility but both lack remodelling and regenerative properties making their utility limited in paediatric patients. With advances in tissue engineering, attempts have been made to fabricate valves with regenerative potential using various polymers, decellularized tissues and hybrid scaffolds. To engineer an ideal heart valve, decellularized bovine pericardium extracellular matrix (DBPECM) is an attractive biocompatible scaffold but has weak mechanical properties and rapid degradation. However, DBPECM can be modified with synthetic polymers to enhance its mechanical properties. In this study, we developed a Bio-Hybrid scaffold with non-cross linked DBPECM in its native structure coated with a layer of Polycaprolactone-Chitosan (PCL-CH) nanofibers that displayed superior mechanical properties. Surface and functional studies demonstrated integration of PCL-CH to the DBPECM with enhanced bio and hemocompatibility. This engineered Bio-Hybrid scaffold exhibited most of the physical, biochemical and functional properties of the native valve that makes it an ideal scaffold for fabrication of cardiac valve with regenerative potential. (C) 2015 Elsevier B.V. All rights reserved.
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    Failure mode and effect analysis of Chitra Heart Valve Prosthesis
    (PROCEEDING OF THE FIRST REGIONAL CONFERENCE - IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY AND 14TH CONFERENCE OF THE BIOMEDICAL ENGINEERING SOCIETY OF INDIA, 1995) Muraleedharan, CV; Bhuvaneshwar, GS
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    Hemocompatible curcumin dextran micelles as pH sensitive pro-drugs for enhanced therapeutic efficacy in cancer cells
    (CARBOHYDRATE POLYMERS, 2016) Raveendran, R; Bhuvaneshwar, GS; Sharma, CP
    Curcumin, a component in spice turmeric, is renowned to possess anti-cancer therapeutic potential. However, low aqueous solubility and instability of curcumin which subsequently affects its bioavailability pose as major impediments in its translation to clinical application. In this regard, we focused on conjugating hydrophobic curcumin to the hydrophilic backbone of dextran via succinic acid spacer to design a pro-drug. The structural confirmation of the conjugates was carried out using FTIR and H-1 NMR spectroscopy. Critical micelle measurement affirmed the micelle formation of the pro-drug in aqueous media. The size distribution and zeta potential of the curcumin-dextran (Cur-Dex) micelles were determined using dynamic light scattering technique. The micellar architecture bestowed curcumin negligible susceptibility to degradation under physiological conditions along with enhanced aqueous solubility. Biocompatibility of the micelles was proved by the blood component aggregation and plasma protein interaction studies. In vitro release studies demonstrated the pH sensitivity release of curcumin which is conducive to the tumour micro environment. Profound cytotoxic effects of Cur-Dex micelles in C6 glioma cells were observed from MU and Live/Dead assay experiments. Moreover, enhanced cellular internalization of the Cur-Dex micelles compared to free curcumin in the cancer cells was revealed by fluorescence microscopy. Our study focuses on the feasibility of Cur-Dex micelles to be extrapolated as promising candidates for safe and efficient cancer therapy. (C) 2015 Elsevier Ltd. All rights reserved.
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    Impedance measurement system for concentric needle electrodes
    (PROCEEDING OF THE FIRST REGIONAL CONFERENCE - IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY AND 14TH CONFERENCE OF THE BIOMEDICAL ENGINEERING SOCIETY OF INDIA, 1995) Khambete, ND; Shashidhara, J; Bhuvaneshwar, GS; Sivakumar, R
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    In vitro cytocompatibility studies of Diamond Like Carbon coatings on titanium
    (BIO-MEDICAL MATERIALS AND ENGINEERING, 2002)
    Diamond Like Carbon (DLC) films were deposited on to titanium (Ti) substrates by Plasma Enhanced Chemical Vapour Deposition (PECVD) process. The quality of the films were checked by Raman spectra and nano-hardness tests. The cytocompatibility of titanium and DLC coated titanium were studied using continuous cell lines of mouse fibroblast cells (L-929), Human Osteoblast cells (HOS) and primary human umbilical cord vein endothelial cells (HUVEC). The cellular responses to the materials were assessed both quantitatively and qualitatively. The adhesion and spreading of cells on materials were compared using Ti as a control. Present study indicates an improved cytocompatibility of DLC coated Ti in comparison to bare Ti.
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    In vitro cytotoxicity and cellular uptake of curcumin-loaded Pluronic/Polycaprolactone micelles in colorectal adenocarcinoma cells
    (JOURNAL OF BIOMATERIALS APPLICATIONS, 2013) Raveendran, R; Bhuvaneshwar, GS; Sharma, CP
    Clinical application of curcumin has been limited due to poor aqueous solubility and consequently minimal systemic bioavailability. We investigated the preparation of curcumin-loaded micelles based on amphiphilic Pluronic/Polycaprolactone (Pluronic/PCL) block copolymer, which proved to be efficient in enhancing curcumin's aqueous solubility. Curcumin-loaded micelles of size below 200 nm was characterized by dynamic light scattering and transmission electron microscopy. The critical micelle concentration (CMC) of the amphiphilic polymer was determined using pyrene as a fluorescent probe. Hemolysis and aggregation studies were investigated to evaluate the blood compatibility of the micelles. Sodium dodecyl sulphate polyacrylamide gel electrophoresis was performed to study the stability of the micelles toward plasma proteins. In vitro cytotoxicity and cellular uptake of the curcumin-loaded micelles were demonstrated in colorectal adenocarcinoma (Caco2) cells. The results indicated that Pluronic/PCL micelles could be a promising candidate for curcumin delivery to cancer cells.
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    Long term tissue response to titanium coated with diamond like carbon
    (BIOMOLECULAR ENGINEERING, 2002)
    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. 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. (C) 2002 Elsevier Science B.V. All rights reserved.
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    Materials for Chitra heart valve prosthesis - A review
    (METALS MATERIALS AND PROCESSES, 1995) Muraleedharan, CV; Bhuvaneshwar, GS; Valiathan, MS
    Materials used in an artificial heart valve, for that matter any implant device, has to be compatible to the biological environment apart from being suitable in terms of physical and engineering properties. This limits the spectrum of materials available for such applications. The course of development of Chitra Heart Valve Prosthesis at Sree Chitra Tirunal institute for Medical Sciences and Technology, Trivandrum was a fascinating study of various aspects of material science, processing and evaluation. A review of different materials tried at various stages of valve development, evaluation of these materials and problems encountered are outlined in this paper.
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    PC based instrumentation as an economic method for quality assurance - An experience based on development of hydrocephalus shunt test system
    (PROCEEDING OF THE FIRST REGIONAL CONFERENCE - IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY AND 14TH CONFERENCE OF THE BIOMEDICAL ENGINEERING SOCIETY OF INDIA, 1995) Nagesh, DS; Nair, SSK; Muraleedharan, CV; Bhuvaneshwar, GS
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    Pullulan-histone antibody nanoconjugates for the removal of chromatin fragments from systemic circulation
    (BIOMATERIALS, 2013) Rekha, MR; Pal, K; Bala, P; Shetty, M; Mittra, I; Bhuvaneshwar, GS; Sharma, CP
    The billions of cells that die in the adult human body daily release considerable amounts of fragmented chromatin in the form of mono- and oligonucleosomes into the circulation in normal individuals, and in higher quantities in many disease conditions. Recent results suggest that circulating chromatin fragments (Cfs) especially from abnormal cells can spontaneously enter into healthy cells to damage their DNA and induce genomic instability. Furthermore, Cfs isolated from cancer patients may induce oncogenic transformation in the recipients' cells. Thus, it follows that if such Cfs emanating from apoptotic cells could be prevented from reaching other cells, it could potentially inhibit pathological conditions, including cancer. Here we have developed pullulan based histone antibody nanoconjugates for the removal of Cfs. Nanoconjugates were developed and various physico-chemical characterizations were carried out. The efficacy of these nanoconjugates on removing Cfs was evaluated both in vitro and in vivo. Our results indicate that nanoconjugates may have therapeutic value in the efficient removal of Cfs, reducing inflammation and fatality in a mouse model of sepsis, and in preventing neutropenia following treatment with Adriamycin. (C) 2013 Elsevier Ltd. All rights reserved.
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    The toxicological quandary in the use of plasticizers in medical devices
    (INDIAN JOURNAL OF MEDICAL RESEARCH, 2004)
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    TTK-Chitra prosthetic heart valve for mitral replacement
    (JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY, 2004) Bhuvaneshwar, GS