Browsing by Author "Rathinam, K"
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Item Assessment of in vivo chromosomal aberrations - Potency of zinc mercapto benzo thiazole(JOURNAL OF BIOMATERIALS APPLICATIONS, 2000)Chromosomal aberrations are microscopically visible changes in the chromosome structure. The double-stranded breaks are the ultimate DNA lesions for chromosomal aberrations. The purpose of the present study was to evaluate the induction of chromosomal aberrations by the rubber accelerator zinc mercapto benzo thiazole (ZMBT). The experiment was designed with five groups, each composed of four Swiss albino mice. The first three groups received ZMBT at 1920, 960, and 483 mu g/20 g animal. The remaining two groups were the vehicle (cotton seed oil) and positive (methyl methane sulphonate) controls. Animals were given a single dose of test; and control samples by IP injection. Colchicine (20 mu g/animal) was administered 90 minutes before sacrificing the animals. All the animals were sacrificed at the end of 36 h by cervical dislocation. Bone marrow preparations were made, stained with Giemsa stain, and examined for chromosomal abnormalities. The results indicated a lack of incidence of chromosomal abnormalities in the test and control groups. However, significant chromosomal abnormalities such as gaps, breaks, and translocations were observed in the positive control group. Hence, the study concluded that ZMBT at different concentrations fails to induce structural chromosomal aberrations in bone marrow cells.Item Biocompatibility studies on silicone rubber(PROCEEDING OF THE FIRST REGIONAL CONFERENCE - IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY AND 14TH CONFERENCE OF THE BIOMEDICAL ENGINEERING SOCIETY OF INDIA, 1995) Mohanan, PV; Rathinam, KItem Cerium stimulates protein biosynthesis in rat heart in vivo(BIOLOGICAL TRACE ELEMENT RESEARCH, 1995)The aim of the study was to ascertain whether Ce, a lanthanide that has been implicated in the pathogenesis of tropical endomyocardial fibrosis, interferes with the biosynthetic repertoire of the cardiac muscle in vivo. Female Sprague-Dawley rats received Ce chloride iv at 1.3 mg/kg body wt.; controls received an equal volume of physiological saline. Rates of protein synthesis and transcription in cardiac muscle, measured in terms of incorporation of (H-3)-phenylalanine and (H-3)-uridine, respectively, into trichloroacetic acid-insoluble material were found to be significantly higher in Ce-treated animals. As low levels of Ce were earlier shown to stimulate collagen as well as noncollagen protein synthesis in cardiac fibroblasts in vitro, the stimulatory effect of the element in vivo reported here supports the speculation that it may influence the expression of proteins Like collagen in the heart and contribute to their accumulation as in endomyocardial fibrosis.Item Development of artificial skin (Template) and influence of different types of sterilization procedures on wound healing pattern in rabbits and guinea pigs(JOURNAL OF BIOMATERIALS APPLICATIONS, 1995)Different types of sterilization procedures have been applied onto artificial skin (Template) developed in our laboratory from polyetherurethane, chitosan and polyvinyl alcohol, etc Studies have been performed to investigate the differences in the wound healing pattern. It appears that quickened wound healing takes place in the rabbit model despite different types of samples and sterilization methods.Item Development of silastic polyurethane (Angioflex) materials with antibacterial agent(JOURNAL OF BIOMATERIALS APPLICATIONS, 1996)Bioimplants incorporated with antimicrobial agents are needed to control Foreign Body Associated Infection (FBAI) in clinical settings. Attempts are made here to develop five different types of polyurethane (Angioflex), viz., (1) bare polymer, (2) bare polymer glow discharged, (3) bare polymer coated with chlorhexidine, (4) chlorhexidine coated polymer glow discharged, and (5) material (4) recoated with another layer of chlorhexidine digluconate. These materials are tested for their in vitro antibacterial effects using disc diffusion technique against five different standard clinical staphylococcus strains, viz., Wood 46 (Staph. aureus), A 182 (Staph. epidermidis), A 313 (Staph. epidermidis), A 61 (Staph. epidermidis), and A 72 (Staph. epidermidis). Maximum antibacterial effects (zone of inhibition) are observed with polyurethanes incorporated with chlorhexidine digluconate (3) and chlorhexidine incorporated and glow discharged (4). Findings of this study indicate that glow discharge does not seem to produce either additive or synergistic antibacterial effects with chlorhexidine digluconate coated Angioflex material.Item Effect of bone wax extract on the frequency of bone marrow erythrocyte micronuclei in mice(VETERINARY AND HUMAN TOXICOLOGY, 1996)The present study evaluated the induction of micronuclear potency of indigenously developed bone wax saline extract. The experiment was designed with 2 batches, each consisting of 8 groups with 3 male Swiss albino mice each. In each batch, the first 3 groups received Chitra's bone wax saline extract and the second 3 groups received Johnson & Johnson bone wax saline extract at 12.5, 25.0 or 50.0 ml/kg body weight ip for 2 d. The remaining 2 groups were vehicle (saline) and positive (cyclophosphamide) controls. Animals were sacrificed 24 and 36 h after the second dosing and bone marrow smears were prepared and evaluated for micronuclei. The Chitra's and Johnson & Johnson's bone wax extracts failed to induce micronuclei in bone marrow erythrocytes of mice.Item Effects of biostability and morphology on host response of polyurethane-based soft tissue implants.(Clinical materials, 1992)Polyurethane has been found to be one of the most successful polymers for soft tissue applications. We have investigated the effect of material biostability and morphology on the host response of polyurethane-based soft tissue implants in rabbits. The polyurethane containing allophanate linkage was prepared by using hexamethylene diisocyanate, polypropylene glycol (400) and 1,4-butane diol. Biuret-based biostable polyurethanes were prepared by using hexamethylene diisocyanate, polytetramethylene glycol and trimethylol propane and water. Samples of circular button and rectangular specimens were implanted subcutaneously in rabbits in the paravertebral region for a post-implantation period of 9 months. Relatively larger polyurethane samples with different morphology elicit a varied tissue response with our candidate polyurethane materials. A favorable tissue response was observed with rectangularly shaped thin polyurethane. Giant cell reaction, absence of fibrous tissue encapsulation and degradation were noticed for the rectangular smooth samples at the end of post-implantation period of 9 months. No malignant changes were noticed in any of these samples.Item Haemolytic potential of hydroxyapatite and beta-tricalcium phosphate bioceramic powders(PROCEEDING OF THE FIRST REGIONAL CONFERENCE - IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY AND 14TH CONFERENCE OF THE BIOMEDICAL ENGINEERING SOCIETY OF INDIA, 1995) Varma, HK; Mohanan, PV; Rathinam, K; Sivakumar, RItem Lack of micronucleus induction by 'Sobatum' in bone marrow erythrocytes of Swiss mice(MUTATION RESEARCH-ENVIRONMENTAL MUTAGENESIS AND RELATED SUBJECTS, 1996)The plant Solanum trilobatum is mainly used for asthma, chronic febrile affections and difficult parturition. The active principle (Sobatum) obtained from the petroleum ether extract of the plant was proved as an anticancer agent by in vitro and in vivo experiments. Here, an effort was made to evaluate the induction of micronucleus by the Sobatum in the bone marrow of swiss mice. The micronucleus assay was conducted after 24 and 72 h of second administration of the Sobatum. The first set of experiments (24 h after second administration) consisted of 4 groups with 3 male Swiss albino mice each. The first group (as control) received only dimethyl sulfoxide, the second, third and fourth groups received different doses of the Sobatum (100, 200, 400 mg/kg body weight), and the fifth group (as positive control) received cyclophosphamide (100 mg/kg body weight) by i.p. injection. In the second set of experiment (72 h after the second administration) consisting of 5 groups, the first, as control, received dimethyl sulfoxide, the second, third and fourth groups received different concentrations of the Sobatum (100, 200, 400 mg/kg body weight), and the fifth group as positive control received cyclophosphamide (100 mg/kg body weight). All the animals of the first and second sets of experiment were killed 24 and 72 h after the second medication (2 consecutive days), and bone marrow smears were prepared, stained with May-Grunwald and Giemsa stain, and evaluated for the evidence of micronucleus, The study concluded that the Sobatum fails to influence the induction of micronuclei in bone marrow erythrocytes of mice 24 and 72 h after the second administration, thereby proving that Sobatum to has no cytogenetic toxic potential.Item Levels of cerium in the tissues of rats fed a magnesium-restricted and cerium-adulterated diet(BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, 1996)Item Magnesium deficiency and cerium promote fibrogenesis in rat heart(BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, 1996)Cerium is a biologically active lanthanide and a major constituent of monazite. The observation that inhalation of particles of cerium causes pneumoconiosis had generated considerable interest in the toxicology of the element (Venugopal and Luckey 1978; Vocatura et al 1983). Cerium tartrate was found to produce cardiac injury and polycythaemia in small animals (Venugopal and Luckey 1978). More recently, tropical endomyocardial fibrosis (EMF), a restrictive cardiomyopathy, was postulated to be the cardiac expression of cerium toxicity in combination with magnesium deficiency (Valiathan et al 1989; Valiathan and Kartha 1990). The postulation was based upon the observation of elevated levels of cerium and depressed levels of magnesium in the cardiac tissue of patients with EMF (Valiathan et al 1989; Valiathan and Kartha 1990). Studies carried out in pursuance of the hypothesis showed that tissue levels of cerium are enhanced in magnesium deficiency (Eapen et al 1996) and that cerium and magnesium deficiency have a synergistic effect on cardiac metabolism (Gunther 1990; Shivakumar and Renuka Nair 1991). Importantly, recent observations on the mode of action of cerium at the molecular level suggested that the element may influence expression of matrix proteins like collagen in the heart and produce fibrosis (Prakash et al 1995; Shivakumar et al 1992). A sequel to these earlier investigations, the present study examined whether chronic ingestion of low doses of cerium would produce cardiac fibrosis in experimental animals. This communication presents evidence that cerium per se or in combination with magnesium deficiency produces subendocardial fibrosis and increase in interstitial cellularity and collagen content in rat heart. It also confirms the earlier observation from this laboratory that magnesium deficiency promotes accumulation of cerium in the cardiac tissue (Eapen el al 1996).Item Mandatory biological testing of Spictra Cardiotomy Reservoir.(Journal of biomaterials applications, 1992)Disposable rigid Spictra Cardiotomy Reservoir is one of the units used in the extracorporeal techniques during open-heart surgery. It was designed, developed, and tested by different groups of our Institute as an indigenous product to offset the prohibitive cost of the imported one. The finished device was subjected to mandatory biological tests, such as pyrogen (in vivo rabbits and in vitro Limulus Amebocyte Lysate test) and sterility tests. It can be concluded from the case study that the device deemed to have passed the test for apyrogenicity and sterility.Item Microtox system, a new approach to the safety evaluation of medical devices(JOURNAL OF BIOMATERIALS APPLICATIONS, 1998)Medical devices of both intra- and extra-corporeal applications may contain leachable toxicants that warrant routine testing using internationally recognized/practiced protocols. An in vitro Microtox system comprising a selected bioluminescence strain of bacteria-Photobacterium phosphorium which emits light as an end product of its respiration, is used to screen out toxicants from biomaterials/devices. A Microtox system was standardized and validated in our laboratory conditions. Our experiences with extract of pyrogenic cardiotomy reservoir, blood filter and systemically toxic (in mice) Barium methacrylate (monomer), and CIBA epoxy polymer materials established a positive correlation with Microtox system. Hence, the Microtox system gives adequate evidence as an alternative in vitro method to evaluate the toxicity of biomaterials and medical devices.Item Observation of Proteus mirabilis in rabbit conjunctivitis and its relation to Vitamin A deficiency(INDIAN VETERINARY JOURNAL, 1997) Ashokan, KK; Umashankar, PR; Lal, GAV; Rathinam, KItem SKIN SENSITIZATION STUDY OF A NEW BIS-GMA BASED DENTAL RESTORATIVE MATERIAL(BIOMATERIALS ARTIFICIAL CELLS AND IMMOBILIZATION BIOTECHNOLOGY, 1993)One of the criteria for the Dental Restorative Material is to not to evoke sensitization reaction when used clinically. The newly synthesized BIS-GMA based Chitra's Dental Material intended for such application was tested for skin sensitization as per the international protocol of test i.e. skin Maximization test in G.Pig. Result of this test showed conclusively that the material is devoid of sensitization potential and fit for clinical application.Item The influence of photodynamic therapy on the wound healing process in rats(JOURNAL OF BIOMATERIALS APPLICATIONS, 2001)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 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/cm(2)) and Nd: YAG laser (30 J/cm(2)). 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.Item THE TERATOGENIC POTENTIAL OF BONE WAX EXTRACT IN RATS(VETERINARY AND HUMAN TOXICOLOGY, 1994)This study evaluated the teratogenic defects of rat brain, eye, heart, urogenital and skeletal systems after po administration of bone wax saline extract on days 9-13 of gestation. The experiment involved 5 groups of 6 pregnant wistar rats each. The vehicle control group received only 50.0 ml distilled water/kg; 3 test groups received 12.5, 25.0 or 50.0 ml of bone wax saline extract/kg; and the last group received 100 mg caffeine/kg as positive control. On the 21st day of gestation all the animals were sacrificed under ether anesthesia and fetuses were collected for routine teratological evaluations. There was no significant change in maternal body weight or food consumption and no external, visceral, skeletal and histological abnormalities in the vehicle control and bone wax dosed groups. Abnormalities were observed in the positive control group.