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Biomedical subjects

P A Kumar

Publications and source records attributed to P A Kumar.

At least 19 recordsLinked to original sources
PubMed2005

Isolation and characterization of a green tissue-specific promoter from pigeonpea [Cajanus cajan (L.) Millsp.].

Expression of rbcS genes encoding small subunit of rubisco, most abundant protein in green tissue, is regulated by at least three parameters--tissue type, light conditions and stage of development. One of the green tissue-specific promoters of rbcS gene family was isolated from pigeonpea by PCR. Expression of uidA gene encoding beta-glucuronidase in the transgenic tobacco plants under the control of pigeonpea rbcS promoter, clearly showed that this promoter was as strong as pea rbcS3A promoter characterized earlier. Study of the sequence similarity with pea rbcS3A promoter, especially the region (boxes I and III) that is required for rbcS3A expression, showed more than 50% divergence. In contrast, pigeonpea promoter sequence isolated in the present study was more similar to that of spinach and rice rbcS promoters.

Base Sequence↗
PubMed2002

Genotoxicity evaluation of polluted ground water in human peripheral blood lymphocytes using the comet assay.

This paper presents the genotoxicity experiments with the ground water collected from an area under the influence of textile dyeing and bleaching industries in Tirupur, Tamilnadu, India. The alkaline single cell gel electrophoresis (SCGE) assay was performed in vitro with human peripheral blood lymphocytes. The cells were exposed to two doses of non-volatile organic agents extracted from ground water samples. Ground water samples were collected from 12 locations distributed in and around Tirupur and extracts were taken at different pHs (without pH adjustment and acidic pH 2.0). The persistence of the DNA damage after exposure to the organic extracts was also studied. All the samples were found to contain substances capable of inducing DNA damage in human lymphocytes. Extracts from acidified waters (pH=2.0) were found to induce more DNA damage than extracts from without pH adjustment (natural pH). The DNA damage was not fully repaired after incubation for 2h at 37 degrees C. The chemical characterization of the sub-fractions revealed the existence of aromatic amines in the extracts, which may be responsible for the DNA damaging activity of the water samples. The results of this investigation demonstrate the application of the comet assay in environmental monitoring studies.

Adult↗
PubMed2001

Expression of type I adenylyl cyclase in intrinsic pathways of the hippocampal formation of the macaque (Macaca nemestrina).

The mossy fiber pathway of the hippocampal formation and type 1 adenylyl cyclase (AC1) have been implicated in long-term potentiation and memory function. Using immunohistochemical labeling and light microscopy we demonstrated intense labeling of AC1 in the mossy fibers and less intense labeling in the molecular layers of both the dentate gyrus and fields CA1, CA2 and CA3 of the hippocampus, i.e. in terminal fields of the perforant pathway. These findings indicate that, in the non-human primate, AC1 is found in the mossy fibers and in terminal fields of the perforant pathway where it may play a role in long term potentiation similar to that demonstrated in the rodent.

Adenylyl Cyclases↗
PubMed2001

Genotoxicity of some sulfur dyes on tadpoles (Rana hexadactyla) measured using the comet assay.

This report presents the results of a genotoxicity study to evaluate the DNA damage caused by four sulfur dyes used in the textile and tannery industries. Alkaline single-cell gel electrophoresis assay (SCGE) was performed on erythrocytes from Rana hexadactyla tadpoles following whole-body exposure to increasing concentrations of the dyes. The dyes, along with their active ingredients, were Sandopel Basic Black BHLN, Negrosine, Dermapel Black FNI, and Turquoise Blue. The dye-treated tadpoles showed significant DNA damage, measured as mean DNA length:width ratio, when compared with unexposed control animals. Among the four tested dyes Sandopel Basic Black BHLN appears to be highly genotoxic, Dermapel Black FNI was least genotoxic, and Negrosine and Turquoise Blue were moderately toxic to R. hexadactyla tadpoles. The tadpoles showed a significant reduction in DNA damage when placed in dechlorinated tap water after exposure for a 24-hr period to the dye solutions.

Aniline Compounds↗
PubMed2001

Characterization of genetic diversity of some serovars of Bacillus thuringiensis by RAPD.

RAPD based fingerprinting of 21 serovars of Bacillus thuringiensis (Bt) representing different serotypes was performed using 19 random decamer primers. A total of 172 polymorphic fragments, ranging in size from 161-2789 bp, were amplified from 13 of the 19 primers. Pairwise genetic similarity analysis revealed very low similarity values, ranging from 3-68%, among the serovars of Bt, indicating high genetic divergence. Nineteen serovars of Bt fell in two major clusters and remaining two formed solitary clusters in the dendogram. Clustering of Bt strains established genetic relatedness between serovars and serotypes. It has been suggested that RAPD analysis can be used for genotypic characterization of Bt to complement flagellar serotyping.

Bacillus thuringiensis↗
PubMed1999

Amino acid substitution in alpha-helix 7 of Cry1Ac delta-endotoxin of Bacillus thuringiensis leads to enhanced toxicity to Helicoverpa armigera Hubner.

Insecticidal proteins or delta-endotoxins of Bacillus thuringiensis are highly toxic to a wide range of agronomically important pests. The toxins are formed of three structural domains. The N-terminal domain is a bundle of eight alpha-helices and is implicated in pore formation in insect midgut epithelial membranes. All the delta-endotoxins share a common hydrophobic motif of eight amino acids in alpha-helix 7. A similar motif is also present in fragment B of diphtheria toxin (DT). Site-directed mutagenesis of Cry1Ac delta-endotoxin of B. thuringiensis was carried out to substitute its hydrophobic motif with that of DT fragment B. The mutant toxin was shown to be more toxic to the larvae of Helicoverpa armigera (cotton bollworm) than the wild-type toxin. Voltage clamp analysis with planar lipid bilayers revealed that the mutant toxin opens larger ion channels and induces higher levels of conductance than the wild-type toxin.

Amino Acid Substitution↗
PubMed1998

Effect of immunostimulation on cytotoxic activity of intestinal intraepithelial lymphocytes of chickens in infectious bursal disease and Eimeria tenella infections.

In chickens, intestinal intraepithelial lymphocytes (iIELs) exhibit spontaneous natural killer (NK) cell like activity, by which they are active in the first line of defence on gut epithelial linings. In the present study, the cytotoxic activity of iIELs was found to be drastically suppressed in chickens experimentally infected with infectious bursal disease (IBD) virus at the age of 5 weeks and also in chickens experimentally infected with Eimeria tenella oocysts at the age of 8 weeks (p < 0.01). As nonspecific immunostimulation is gaining importance, immunostimulants such as immunostimulating Mycobacterium phlei (ISMP) and bone marrow culture supernatant (BMCS) were tested for their influence on the functional activity of iIELs of chickens in IBD and E. tenella infections. In chickens primed with ISMP a week prior to respective experimental infections, it was found that the cytotoxic activity of iIELs was restored (p < 0.01) in both IBD and E. tenella infections. At the same time, in chickens primed with BMCS a week prior to respective experimental infections, the cytotoxic activity of iIELs was restored to a certain extent (p < 0.01) in E. tenella but not at all in IBD infection. These results showed that application of immunostimulation helped potentiate and restore the functional activity of iIELs of chickens in IBD and E. tenella infections.

Animals↗
PubMed1997

Zinc status of breastfed and formula-fed infants of different gestational ages.

Zinc status in 186 full term and preterm infants was determined at birth, and 3, 6, 9, and 12 months of age along with determination of zinc levels in breast or formula milk to find out if routine zinc supplements are needed during infancy. The leukocyte and plasma zinc levels in all breastfed infants were high at birth and gradually declined reaching lowest values by 4-6 months of age, and improved to normal levels by 9 months following weaning. The preterm infants however, had significantly (P < 0.05) higher leukocyte zinc (213.6 +/- 46.91 micrograms/10(10) cells) at birth compared to term infants. Colostrum of all the mothers had higher zinc concentrations which declined to significantly lower levels in breastmilk by 4-6 months of lactation, corresponding to the age when the breastfed infants had lower zinc levels. The improvement of the levels to normal after weaning suggests that the fall in zinc status during early infancy could be a transient phenomenon which could be reversed by proper weaning, thus strengthening the plea for timely food supplements rather than the need for single nutrient supplements. Formula-fed full term infants had significantly lower leukocyte zinc levels (49.3 +/- 2.59 micrograms/10(10) cells) at 3 months of age compared to breastfed infants of the same age (92.8 +/- 14.04 micrograms/10(10) cells). Even these infants improved their zinc status after weaning on par with breastfed infants. The functional significance of their transient, but low zinc values during early infancy needs to be investigated.

Analysis of Variance↗
PubMed1996

A colorimetric assay to evaluate the cytotoxic activity of the intestinal intraepithelial lymphocytes of chickens.

After the successful use of 3-[4,5-(dimethylthiazol-2-yl)]-2,5-diphenyltetrazolium bromide (MTT) in cell proliferation assays, its use has been established by different workers in cytotoxicity assays and research on leukaemia. In the present study, a colorimetric assay using MTT was adopted to evaluate the cytotoxic activity of chicken intestinal intraepithelial lymphocytes (iIELs), which constitute an important cellular component of the gut-associated lymphoid tissue (GALT). These iIELs are found to exhibit natural killer (NK) cell-like cytotoxic activity, which is spontaneous, non-MHC-restricted, and does not need to be primed. Hitherto, conventional chromium-release assays have been used to evaluate the cytotoxic activity of iIELs, but these assays have disadvantages such as radiation hazards and loss of the cells in washing steps. The mean percentage cytotoxic activity of chicken iIELs evaluated by the colorimetric assay was 90.37 +/- 2.53 in a group of 5-week-old chickens and 80.2 +/- 3.45 in a group of 8-week-old chickens. These findings established the successful use of a colorimetric assay using MTT for evaluating the cytotoxic activity of chickens iIELs.

Animals↗
PubMed1995

Cross-face reanimation of the paralysed face, with a single stage microneurovascular gracilis transfer without nerve graft: a preliminary report.

This paper describes a method of cross-face reanimation of the paralysed face by a single stage transfer of gracilis. In this method, the nerve to the gracilis is kept long and tunnelled across the upper lip and joined directly to branches of the facial nerve on the normal side. The method avoids the need for a nerve graft and shortens the period of rehabilitation by 12 months. The results in 3 cases were good in 2 cases and fair in 1 case.

Adult↗
PubMed1993

Integration of a cyanobacterial protein involved in nitrate reduction (narB) into isolated Synechococcus but not into pea thylakoid membranes.

Chimeric genes comprised of Rubisco small subunit transit peptide fused in frame with full-length and truncated sequences of a nitrate reductase (narB) structural gene of Synechococcus were constructed. Fusion proteins were synthesized in a rabbit reticulocyte system. In thylakoido integration of synthetic proteins resulted in the association of the full-length narB-coded protein to the Synechococcus photosynthetic membranes. The membrane-associated protein was sensitive to trypsin treatment but could not be removed by washing in the presence of NaBr. Trypsin pretreatment of thylakoids abolished the capability for association. The association of the narB-coded protein with thylakoids might require another membrane protein whose identity is not known. It is proposed that the Synechococcus narB polypeptide is a peripheral, membrane bound protein anchored to the thylakoids via a short hydrophobic domain while the major part of the protein resides on the outer side of the thylakoid membranes. The chimeric narB proteins were processed and imported by intact pea chloroplasts in vitro; however, the mature proteins were found localized in the stroma and not in the thylakoid membrane fraction. Similarly, the attempt to integrate the protein in vitro into isolated pea thylakoid membranes failed although these membranes incorporate early light-inducible proteins.

Animals↗
PubMed1992

Radical microarteriolysis in the treatment of vasospastic disorders of the hand, especially scleroderma.

Arterial spasm due to exaggerated sympathetic response is an important mechanism for Raynaud's phenomenon in scleroderma associated often with periadventitial scarring. The results of cervical sympathectomy have been unsatisfactory in the upper limb because of additional sympathetic pathways. Flatt therefore devised a distal sympathectomy by stripping the vessels of their adventitia over a short length of artery. The results of this operation were found by Wilgis in a large series to be poor in patients with scleroderma. A radical distal microarteriolysis including adventitia and surrounding scar is described and the results in 13 patients, 11 with scleroderma, are reported. Minimum follow-up is one year. All patients had relief from pain at rest and healing of painful ulceration. Mild recurrence of small ulcers was seen in only four patients.

Adult↗
PubMed1991

Long term results of submandibular gland transfer for the management of xerophthalmia.

Free submandibular gland transfer is potentially the best surgical solution to total xerophthalmia. Experimentally, gland function has only previously been followed for 2 months. This study was designed to investigate the long term effects of free transfer on gland function. Simultaneous creation of experimental xerophthalmia and free microvascular transfer of the submandibular gland to the orbit was completed in 10 rabbits. Two died before the end of the experimental period and the study was based on the remaining eight. Six months after transfer, five of the eight transferred glands were histologically normal and contained healthy neurones and nerve terminals. In these animals, tear secretion in the transfer eye was significantly greater than that of the control eye at 2 (p less than 0.05) and 6 months (p less than 0.02) after transfer. In the transfer eye, tear secretion was also found to have significantly increased from preoperative levels at 2 (p less than 0.05) and 6 months (p less than 0.01). The observed innervation of the transferred glands may play a role in maintaining secretion in the long term.

Animals↗
PubMed1990

Microvascular submandibular gland transfer for the management of xerophthalmia; an experimental study.

Free submandibular salivary gland transfer was investigated as a method of treatment for xerophthalmia. Xerophthalmia was created in rabbits by surgical removal of the lacrimal gland and the incidence of corneal ulceration was seen to correlate with the decrease in tear secretion. Microvascular transfer of the submandibular salivary gland to drain saliva into the conjunctival fornix prevented the development of corneal ulceration in 63% of the cases.

Amylases↗
PubMed1990

Photorespiratory ammonia assimilation in the leaves of barley, sorghum and Moricandia arvensis.

Effects of methionine sulphoximine (MSX) on glutamine synthetase activity and ammonia accumulation in the leaves of barley, sorghum and Moricandia arvensis were studied. Glutamine synthetase activity of sorghum leaves was relatively resistant to MSX treatment during initial stages. All the three plant species exhibited considerable accumulation of ammonia arising from non-photorespiratory sources, in response to MSX treatment. Minimal estimates of the rate of glycine decarboxylation were made employing MSX and isonicotinyl hydrazide together in the treatment solution. Changes in the pool sizes of amino acids involved in photorespiratory nitrogen metabolism as affected by MSX have also been investigated.

Amino Acids↗
PubMed1989

Liposuction in the treatment of lymphoedema; a preliminary report.

Liposuction was used in the treatment of primary and secondary lymphoedema in 19 patients. Seven patients had no previous surgical treatment and 12 had previously been treated with microlymphaticovenous anastomoses and/or surgical reduction. There was subjective improvement in 11 of the 13 patients available for follow-up. There was objective improvement in 10 of the 11 patients with unilateral lymphoedema, with an average reduction of 23% of the excess volume. Seven of the 13 patients were on conservative treatment prior to liposuction. The average reduction in this group was 20.5%. The average follow-up time was 9.5 months. From this preliminary report it can be concluded that liposuction, either as a primary procedure or as an adjunct, can be a useful procedure in the treatment of both primary and secondary lymphoedema.

Arm↗