Search PubMed⌕ Search

Biomedical subjects

V Sundararaman

Publications and source records attributed to V Sundararaman.

16 recordsLinked to original sources
PubMed1997

In vivo induction of sister chromatid exchange in mouse bone marrow following oral exposure to commercial formulations of alpha-cyano pyrethroids.

In vivo genetic toxicity potential of cypermethrin and deltamethrin, two alpha-cyano pyrethroid insecticides was evaluated through induction of sister chromatid exchange in mouse bone marrow cells. Groups of four healthy, adult, male albino mice were each administered with a single oral dose of 10.6, 21.1 and 32 mg cypermethrin a.i./kg b.w. or 6.6, 13.2 and 20 mg deltamethrin a.i./kg b.w. in peanut oil. For reference, a peanut-oil vehicle control and cyclophosphamide (20 mg/kg, i.p.) positive control group of animals were run in parallel. Sister chromatid exchange (SCE) analysis in bone marrow metaphase chromosomes, 24 h post-treatment, revealed modest induction with statistical significance at the highest test dose of both insecticides as compared to the vehicle control group. Further, the SCE induction by cypermethrin was more prominent than by deltamethrin. Marked induction of SCE frequency by exposure to cyclophosphamide, an alkylating mutagen, lent authenticity to these observations which, together with earlier evidence of mitotic and chromosomal abnormalities by these pyrethroids, substantiated their genetic toxicity potential and susceptibility of mammals to consequent risks.

Administration, Oral↗
PubMed1994

Cytogenetic effects of deltamethrin on rat bone marrow.

Deltamethrin, a synthetic pyrethroid insecticide, was administered to adult female albino rats as a single i.p., s.c., or oral dose of 5.6, 8.4, or 11.2 mg/kg b.w. or repeated i.p. doses of 2.24 mg/kg b.w. for five consecutive days (cumulative dose 11.2 mg/kg b.w.). This treatment inhibited the mitotic index in a dose-dependent manner and increased the frequency of chromosome aberrations in the bone marrow at 24 h post exposure. The parenterally (i.p. and s.c.) administered deltamethrin appeared more effective than the oral gavage for eliciting its cytotoxicity and genetic toxicity potential. The frequency of micronucleated erythrocytes in the bone marrow was also increased at 30 h following a single i.p. dose of 5.6, 8.4, or 11.2 mg/kg b.w. The most prevalent abnormality observed in this study was endomitotic reduplication of chromosomes which, along with mitotic inhibition and micronucleus induction, indicated microtubular/mitotic spindle poisoning by deltamethrin. The increased frequency of chromosome aberrations and micronucleated erythrocytes also suggests a clastogenic potential of deltamethrin. These observations indicate the in vivo susceptibility of mammals to the genetic toxicity potential of deltamethrin.

Animals↗
PubMed1983

Antigenic variation during cellular aging in Paramecium tetraurelia.

Clones of Paramecium tetraurelia undergoing cellular aging were exposed to two antisera, anti-32 and anti-25, raised against surface antigen isolated from cells grown at 32 degrees C or 25 degrees C. When young clones were exposed to the two antisera about 50% were immobilized by anti-32 while others were not immobilized by either antisera. These clones were grouped as group A or B depending upon their sensitivity or nonsensitivity to the two antisera. Young cells of group A were immobilized by anti-32 and during aging these cells either maintained the same antigenic type or transformed to another. Young group B clones were not immobilized by either antisera but gradually became sensitive to anti-32. Some clones from both groups showed sensitivity to both antisera. The possible mechanism of antigenic variation during fission age is discussed.

Animals↗
PubMed1979

The ultrastructure of the striated muscle of the tail of Cercaria chackai, nadakal et al., 1969.

The electron microscopic study of the tail of Cercaria chackai reveals that it contains four sets of striated muscle bundles located central to the nonstriated circular and longitudinal muscles. The striated muscle consists of longitudinally oriented lamellar myofibres. Each myofibre contains a single "U" shaped myofibril. The banding pattern is analogous to that of vertebrate striated muscle. The sarcolemma is a simple surface membrane. There are no transverse tubular extensions of sarcolemma. The sarcoplasmic reticulum (SR) is very well developed with cisternae, tubules, and vesicles. SR cisternae form dyadic couplings with the sarcolemma. There is a set of flattened tubules of SR origin traversing the myofibril exactly at the Z region. These tubules are unique to the striated muscle of the cercarian tail and may have functional significance. A diagrammatic reconstruction of the myofibre is presented.

Animals↗
PubMed1975

Dose distributions and mean doses in cylindrical cavities of bone marrow on X-ray irradiation.

Dose distributions as well as mean doses to cylindrical cavities of bone marrow on X-ray irradiation have been calculated using (a) Monte Carlo method and (b) a simplified straight line approximation method. The results are compared with earlier published ones. Point doses differ appreciably from the earlier results by as much as 40 percent at some points, whereas mean doses agree to within 10 percent for all the three methods.

Bone Marrow↗
PubMedDate not supplied

Morphological changes in aging cell lines of Paramecium aurella. I. Alterations in the cytoplasm.

Electron microscopical examination of aging P. aurelia revealed that definitive changes occur in the cytoplasm of old cells. There was an increase in the number of mitochondria and lysosomal bodies as well as the appearance of large dense bodies and autophagous vacuoles. The mitochondria were altered morphologically and many appeared to be coalesced with lysosome-like bodies and were also observed to be degenerating within autophagous vacuoles. The large dense bodies were considered to be similar to the lipofuscin or age pigments reported in other aging cells. The relationship of the large dense bodies to the lipofuscin pigments and their probable origin are discussed as is the involvement of the cytoplasm in the aging death process in P. aurelia.

Aging↗
PubMedDate not supplied

Morphological changes in aging cell lines of Paramecium aurelia. II. Macronuclear alterations.

Electron microscopic examination of aging P. aurelia showed that the macronucleus undergoes characteristic structural changes. The surface of the aging macronucleus was highly invaginated. Compared with young macronuclei, the chromatin bodies appeared to be smaller and condensed, and were fewer per unit area of the aging macronucleus. The nucleolar bodies also showed morphological alterations. In many aging macronuclei the nucleolar bodies appeared to be aggregated. Large ring-shaped or coiled loops of nucleoli were also observed. These changes in the ultrastructure of macronucleus in the aging paramecia suggest that the macronucleus in the aging cells is less active in the synthesis of macromolecules and transport of material to the cytoplasm.

Animals↗
PubMedDate not supplied

Morphological changes in aging cell lines of Paramecium aurelia. III. The effects of emetine on polysome formation.

The effect of emetine, an inhibitor of cellular protein synthesis, on young and old cell lines of Paramecium aurelia was studied. Emetine treatment resulted in the accumulation of ribosomal aggregates in the form of helices or rosettes. In treated young cells, large patches of endoplasmic reticulum with clusters of ribosomes were frequently observed. These structures were smaller in treated aging cells. Owing to the association of these ribosomal clusters with endoplasmic structures, they were called "ribosomal complexes". In young cells the polysome helices were more numerous, compared to those of old cells. The difference in the number of polysomes between the young and old cells appeared to be related to the number of ribosomes. The results suggested that in aging cells there were fewer ribosomes and less RNA. In very old cells the ribosomal particles appeared to be altered morphologically.

Animals↗