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Biomedical subjects

K Raghu

Publications and source records attributed to K Raghu.

At least 19 recordsLinked to original sources
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↗
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↗
PubMed1997

Effect of temperature on antagonistic and biocontrol potential of Trichoderma sp. on Sclerotium rolfsii.

Sclerotium rolfsii is a destructive soil-borne and post-harvest plant pathogen. Use of the antagonistic fungus Trichoderma sp. has been earlier reported by us to successfully control this pathogen under post-harvest conditions. In the present paper we report on the effects of temperature on the growth and biocontrol potential of Trichoderma sp. on S. rolfsii. Experimental results indicated that S. rolfsii and Trichoderma sp. have different temperature optima for growth: 30-35 degrees C for the pathogen and 25-30 degrees C for the antagonist. In dual culture, Trichoderma over-grew S. rolfsii at 25 degrees C and 30 degrees C, but at 35 degrees C and 37 degrees C, S. rolfsii over-grew the colony of Trichoderma. Trichoderma produced higher concentration of fungi-toxic metabolites in broth culture at higher temperatures. In bioassays using ginger slices and whole rhizomes, it has been demonstrated that Trichoderma is not very effective in suppressing S. rolfsii at temperatures above 30 degrees C. In light of these results, possible mechanisms of biocontrol of S. rolfsii as a post-harvest pathogen has been discussed. Storage temperature has been suggested as a critical factor in biocontrol of S. rolfsii.

Journal Article↗
PubMed1996

Novel polypeptides induced by the insecticide lindane (gamma-hexachlorocyclohexane) are required for its biodegradation by a Sphingomonas paucimobilis strain.

When exposed to the potent insecticide gamma-hexachlorocyclohexane or lindane, a Sphingomonas paucimobilis strain rapidly synthesized 7 novel polypeptides and concomitantly gained the ability to degrade lindane. Synthesis of these proteins was switched-off subsequent to the disappearance of lindane from the medium. Treatments which induced the synthesis of identical proteins also conferred on cells the ability to degrade lindane. In contrast, cells blocked in protein synthesis could not be induced to degrade lindane. The close correspondence observed between expression of lindane-induced proteins and gamma-hexachlorocyclohexane catabolism strongly implicates these novel proteins in lindane biodegradation.

Biodegradation, Environmental↗
PubMed1989

Effects of DDT on the growth of crop plants.

The effects of DDT on the germination and growth of plants were studied using many crop species. Of the species tested, oil-rich seeds of plants, such as peanut (Arachis hypogaea) and mustard (Brassica juncea), were more prone to DDT induced inhibition of germination and subsequent plant growth than cereals, pulses and fibre crops, like rice (Oryza sativa), barley (Hordeum vulgare), mung bean Vigna radiata), pigeon pea (Cajanus cajan) and cotton (Gossypium hirsutum). Studies with (14)C labelled DDT showed that insecticide uptake by seeds was directly proportional to seed size. However, there was no direct relationship between DDT uptake by the seeds and its subsequent translocation to the growing regions or the degree of growth inhibition. Data suggest that oil content of the seeds per se has a bearing on the susceptibility or tolerance of a plant to DDT. It is suggested that lipids of the plant cell solubilize and disperse DDT in the cytoplasm, which, in turn, affects normal metabolism within the cell.

Journal Article↗
PubMed1983

Fatal renal haemorrhage following haemodialysis in a patient with obstructive uropathy.

A 22-year-old male with obstructive uropathy and renal failure was given pre-operative haemodialysis. He collapsed five hours later. Autopsy revealed massive intrarenal haemorrhage and rupture of a dilated superior calyx intraperitoneally. Anticoagulation employed during haemodialysis was probably responsible for this spontaneous renal haemorrhage and subsequent calyceal rupture.

Adult↗
PubMed1981

Traumatic organized hematoma of the spermatic cord.

We report a case of an organized hematoma of the spermatic cord, resulting from direct blunt injury, and review the literature related to this condition. The probable factors accounting for the infrequent occurrence of this lesion in association with external genital trauma are discussed.

Adult↗