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Biomedical subjects

S P Kale

Publications and source records attributed to S P Kale.

At least 19 recordsLinked to original sources
PubMed2006

Correct anatomical location of entry point for antegrade femoral nailing.

Closed intramedullary nailing is a well-accepted method of treatment for femoral shaft fractures. The issue of the correct entry point for antegrade nailing remains a matter of controversy, and the literature is confusing. We reviewed the opinions of 100 orthopaedic surgeons by means of questionnaires. Only four surgeons were able to identify and label their respective entry points for femoral nailing correctly, possibly because of incorrect illustration in publications or errors in terminology. Although the piriformis fossa appears to be the ideal entry point, the importance of exact localisation in the sagittal plane, centered over the axis of medullary canal, cannot be overlooked.

Bone Nails↗
PubMed2006

Adsorption-desorption of HCH and endosulfan on a soil.

Sorption - desorption of HCH (1,2,3,4,5,6 - Hexachlorocyclohexane) and Endosulfan (1,2,3,4,7,7 - Hexachlorobicyclo [2,2,1] -2 - heptene - 5,6 - bisoxy methylene sulfite) on soil was studied using the batch equilibration technique with initial concentrations for the two chemicals ranging from 0.03 to 340 microg ml(-1), which corresponds to a field application rate of 0.1 2.0 kg m(-2). Calculated slopes of the Freundlich sorption isotherms were near to 1. The Kf, Kd, and Koc values determined for endosulfan were at least an order of magnitude greater than that determined for HCH. Kf values were 209 and 8035 for HCH and Endosulfan respectively. Hysteresis was observed for desorption of both the chemicals. Studies showed that Endosulfan and HCH binding to soil was strong and desorption cannot be predicted from adsorption isotherms only.

Adsorption↗
PubMed2002

Uptake of 14C-chlorpyrifos by clams.

The uptake of 14C-chlorpyrifos by clams (Katalysia opima) was studied to determine the bioaccumulation potential over a period of five days. Chlorpyrifos was applied to a model ecosystem in beakers at the rate of 3 mg l(-1) of seawater. Clams showed a maximum uptake of 14C-chlorpyrifos in the first 8 hours of exposure. Subsequently these residues decreased significantly and at the end of 5 days about 1.5% of the applied activity could be recovered from the clam samples. The half-life of chlorpyrifos in this marine water system was about a day. However, after 5 days about 28% of the applied 14C-activity was present in water. This may be significant and could possibly play a role in finding the residue of this insecticide in water bodies. Clams brought about rapid degradation of chlorpyrifos in the first 48 hours. The stabilised residues in water were reflected later in clams.

Animals↗
PubMed2002

Metabolism of 14C-naphthalene in marine sediments.

Metabolism of 14C-naphthalene was studied in aerobic and anaerobic marine sediments from the Mumbai coast, India using a continuous flow-through system for 5 weeks. There was no volatilisation of naphthalene from anaerobic sediment. Naphthalene underwent more extensive mineralization in aerobic sediment (31.6% of the applied activity) than in anaerobic sediment (5% of the applied activity). No metabolite of naphthalene was present in sediments at the end of the incubation period.

Bacteria, Aerobic↗
PubMed2001

Monitoring of organochlorine pesticide residues in the Indian marine environment.

Organochlorine pesticide residues in sediment and fish samples collected from the east and west coasts of India are presented. HCH isomers and DDT and its metabolites are the predominantly identified compounds in most of the samples. Despite the higher quantity of consumption, HCH and DDT levels in fish in India were lower than those in temperate countries suggesting a lower accumulation in tropical fish, which could be due to rapid volatilization and degradation of these insecticides in the tropical environment. The predominance of alpha- and beta-HCH reflect the use of technical grade HCH in India. The high temperature in the tropics also enhances the elimination rate of chemicals in fish, as the biological half-lives of semivolatile compounds such as DDT are short at high temperature.

Animals↗
PubMed2001

Degradation of 14C-carbofuran in soil using a continuous flow system.

14C-carbofuran underwent considerable mineralization (approximately 30% of the applied activity) in Vertisol soil under moist and flooded conditions during 60 days incubation. Bound residues were formed under both the conditions, the extent being more in moist soils (approximately 55% of the applied activity) than under flooded conditions (approximately 41% of the applied activity). 3-Keto carbofuran was the only significant metabolite observed under flooded conditions.

Carbofuran↗
PubMed2001

Bioremediation of DDT in soil by genetically improved strains of soil fungus Fusarium solani.

Bioremediation of DDT in soil by genetically improved recombinants of the soil fungus Fusarium solani was studied. The parent strains were isolated from soil enriched with DDD or DDE (immediate anaerobic and aerobic degradation products of DDT), as further degradation of these products are slow processes compared to the parent compound. These naturally occurring strains isolated from soil, however, are poor degraders of DDT and differed in their capability to degrade its metabolites such as DDD, DDE, DDOH and DBP and other organochlorine pesticides viz. kelthane and lindane. Synergistic effect was shown by some of these strains, when grown together in the medium containing DDD and kelthane under mixed culture condition. No synergism in DDE degradation was observed with the strains isolated from enriched soil. DDD-induced proteins extracted from individual culture filtrate (exo-enzyme) when subjected to SDS-Polyacrylamide Gel Electrophoresis (SDS-PAGE) showed complementary polypeptide bands in these strains i.e., each strain produced distinct DDD degrading polypeptide bands and the recombinant or hybrid strains produced all of the bands of the two parents and degraded DDD better than the parental strains. Recombinant hybrid strains with improved dehalogenase activity were raised by parasexual hybridisation of two such complementary isolates viz. isolate 1(P-1) and 4(P-2) showing highest complementation and are compatible for hyphal fusion inducing heterokaryosis. These strains are genetically characterised as Kel+Ben(R)DBP-Lin- and Kel-Ben(r)DBP+Lin+ respectively. Recombinants with mixed genotype, i.e., Kel+Ben(R)DBP+Lin+ showing superior degradation quality for DDT were selected for bioremediation study. Recombination was confirmed by polypeptide band analysis of DDD induced exo-proteins from culture filtrate using SDS-Polyacrylamide Gel Electrophoresis (PAGE) and RAPD (Random Amplified Polymorphic DNA) of genomic DNA using PCR (Polymerase Chain Reaction) technique. SDS-PAGE showed combination of DDD induced polypeptide bands characteristic of both the parents in the recombinants or the hybrids. PCR study showed the parent specific bands in the recombinant strains confirming gene transformation.

Biodegradation, Environmental↗
PubMed1999

Studies on degradation of 14C-DDT in the marine environment.

Degradation of 14C-DDT was studied in a marine ecosystem for 60 days and in marine sediments under moist and flooded conditions using a continuous flow system for a period of 130 days. 14C-DDT residues were recovered in sediments of the marine ecosystem at uniform level of 60-65% of the applied 14C-activity throughout the incubation period. DDD was a major metabolite in sediments while DDMU was a major metabolite in clams. Clams brought about substantial degradation of DDT. However, 14C-residues recovered form clams are not suggestive of significant bioaccumulation. In the continuous flow experiment, under both moist and flooded conditions, DDT underwent degradation and about 22% of the applied 14C-activity was recovered as volatiles under both conditions. In sediments, extractable 14C-residues accounted for about 30 and 19% under moist and flooded conditions, respectively. DDT was the major compound in extractable residues as identified by TLC-autoradiographic procedures. More bound residues were formed under flooded than under moist conditions.

Animals↗
PubMed1999

Studies on degradation of 14C-chlorpyrifos in the marine environment.

Degradation of 14C-chlorpyrifos was studied in a marine ecosystem for 60 days and in marine sediment under moist and flooded conditions using a continuous flow system allowing a total 14C-mass balance for a period of 40 days. In the marine ecosystem, 14C-chlorpyrifos underwent rapid degradation and very little (1-2%) 14C-residues of the applied activity were detected after two months in sediments. Clams were major component of the ecosystem and played a significant role in degradation of the insecticide. In the continuous flow system chlorpyrifos did not undergo substantial mineralization. Volatilization accounted for 0.8-1% loss during first ten days of application. The amounts of extractable 14C-activity were higher in flooded sediments than in moist sediment. More bound residues were formed under moist conditions. TCP (3,5,6-trichloro-2-pyridinol) was the major degradation product formed under both moist and flooded conditions, its formation being higher in the latter conditions. These studies underline the role of clams in degradation of chlorpyrifos and lack of microbial degradation. In absence of clams, chlorpyrifos underwent abiotic degradation in marine sediment with formation of bound residues.

Animals↗
PubMed1999

Caffeine protects mice against whole-body lethal dose of gamma-irradiation.

Administration of caffeine (1,3,7-trimethylxanthine), a major component of coffee, to Swiss mice at doses of 80 or 100 mg/kg body weight 60 min prior to whole-body lethal dose of gamma-irradiation (7.5 Gy) resulted in the survival of 70 and 63% of animals, respectively, at the above doses in contrast to absolutely no survivors (LD-100/25 days) in the group exposed to radiation alone. Pre-treatment with a lower concentration of caffeine (50 mg/kg) did not confer any radioprotection. The protection exerted by caffeine (80 mg/kg), however, was reduced from 70 to 50% if administered 30 min prior to irradiation. The trend statistics reveal that a dose of 80 mg/kg administered 60 min before whole-body exposure to 7.5 Gy is optimal for maximal radioprotection. However, caffeine (80 mg/kg) administered within 3 min after irradiation offered no protection. While there is documentation in the literature that caffeine is an antioxidant and radioprotector against the oxic pathway of radiation damage in a wide range of cells and organisms, this is the first report demonstrating unequivocally its potent radioprotective action in terms of survival of lethally whole-body irradiated mice.

Animals↗
PubMed1996

Differential response to UV stress and DNA damage during the yeast replicative life span.

The yeast Saccharomyces cerevisiae is mortal. Before they die, individual yeasts bud repeatedly producing a finite number of progeny, which have the capacity for a full life span. A feature of aging in many species is the waning of resistance to stress. To determine whether this is the case in yeast, we have examined the survival (viability) of age-synchronized populations of yeasts of various ages, spanning youth, midlife, and old age, after irradiation with ultraviolet light (UV). Resistance to UV was biphasic. There was an increase through midlife, followed by a precipitous decline. For comparison, another mutagenic agent, ethyl methanesulfonate (EMS), was tested in the same way. The response was very different. A uniphase decrease in resistance to this DNA-alkylating agent was found with a plateau later in life. The results argue that the increase in resistance to UV with age is an active process and not simply a monotonic age change. RAS2 is among the genes that determine yeast longevity. This gene is preferentially expressed in young cells and has a life span-extending effect on yeasts. One known function of RAS2 is to mount a protective response to irradiation by UV, which occurs independently of DNA damage. The distinction between UV and EMS found here is consistent with the notion that resistance to UV plays a role in yeast longevity in a manner not related to DNA damage. Furthermore, it suggests that RAS2 may participate in this response. We have found that RAS2 expression and UV resistance coincide in middle-aged yeasts bolstering this possibility. These data and the eclipse in activity of several longevity determining genes at midlife in yeasts also raise the possibility that active life maintenance processes function through this period, after which the organism operates on any remaining reserves until death.

DNA Damage↗
PubMed1996

Characterization of experimentally induced, nonaflatoxigenic variant strains of Aspergillus parasiticus.

Six previously isolated, nonaflatoxigenic variants of Aspergillus parasiticus, designated sec mutants, were characterized morphologically by electron microscopy, biochemically by biotransformation studies with an aflatoxin precursor, and genetically by Northern (RNA) hybridization analysis of aflatoxin biosynthetic gene transcripts. Scanning electron micrographs clearly demonstrated that compared with the parental sec+ forms, the variant sec forms had an abundance of vegetative mycelia, orders of magnitude reduced number of conidiophores and conidia, and abnormal metulae. Conidiospores were detected in sec cultures only at higher magnifications (x 500), in contrast to the sec+ (wild-type) strain, in which abundant conidiospores (masking the vegetative mycelia) were observed at even lower magnifications (x 300). All sec+ forms, but none of the sec forms, showed bioconversion of sterigmatocystin to aflatoxins. Northern blots probed with pathway genes demonstrated lack of expression of both the aflatoxin biosynthetic pathway structural (nor-1 and omtA) and regulatory (aflR) genes in the sec forms; PCR and Southern hybridization analysis confirmed the presence of the genes in the sec genomes. Thus, the loss of aflatoxigenic capabilities in the sec form is correlated with alterations in the conidial morphology of the fungus, suggesting that the regulation of aflatoxin synthesis and conidiogenesis may be interlinked.

Aflatoxins↗
PubMed1994

Divergent roles of RAS1 and RAS2 in yeast longevity.

Individual cells of the yeast Saccharomyces cerevisiae have a limited replicative life-span. The role of the genes RAS1 and RAS2 in yeast longevity was examined. Over-expression of RAS2 led to a 30% increase in the life-span on average and postponed the senescence-related increase in generation time seen during yeast aging. No life-span extension was obtained by overexpression of RAS1. However, deletion of RAS1 prolonged the life-span. These results suggest that RAS1 and RAS2 play reciprocal roles in determining yeast longevity. RAS1 and RAS2 mRNA and protein levels declined with replicative age, suggesting a diminishing impact on yeast longevity. The major known pathway through which Ras proteins function in yeast involves stimulation of adenylate cyclase. No evidence for a life-span-extending effect of elevated intracellular cAMP was found. Indeed, high intracellular cAMP was associated with curtailed life-span. A similar decrease in life-span was found on disruption of BCY1, which codes for the regulatory subunit of protein kinase A, the downstream target of cAMP. Importantly, overexpression of an effector domain mutant of RAS2, defective in stimulation of adenylate cyclase, prolonged life-span to the same extent as the wild-type gene, suggesting that the cAMP pathway is neither sufficient nor necessary for increased longevity.

Adenylyl Cyclases↗
PubMed1994

Cloning and characterization of LAG1, a longevity-assurance gene in yeast.

The yeast Saccharomyces cerevisiae has a finite life span that is measured by the number of times the individual cell divides. The gene coding for one of several transcripts that are differentially expressed during the replicative life span has been cloned. The nucleotide sequence revealed an open reading frame capable of encoding a transmembrane protein of 411 amino acids that displays no significant similarities to any known proteins. Nevertheless, sequences similar to this gene were found in several mammals, including humans. The transcript levels decreased with replicative age of yeast cells. A gene deletion in haploid cells resulted in a pronounced increase (approximately 50%) in mean and in maximum life span. These results indicate that this gene, which we call LAG1, plays a role in determining yeast longevity.

Amino Acid Sequence↗