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Biomedical subjects

G Reddy

Publications and source records attributed to G Reddy.

At least 37 records · Page 2Linked to original sources
PubMed1999

Impact of mid day meal program on educational and nutritional status of school children in Karnataka.

OBJECTIVE: To assess the effect of the Mid Day Meal (MDM) Program on enrollment, attendance, dropout rate and retention rate in the schools and its impact on nutritional status as well as on school performance. DESIGN: Comparison by multistage random sampling. SUBJECTS: Primary school children, who are attending the school in the MDM and non-MDM areas. RESULTS: A total of 2,694 children (MDM: 1361; Non-MDM : 1333) from 60 schools were covered in the study. Results of the study indicated better enrollment (p<0.05) and attendance (p<0.001), higher retention rate with reduced dropout rate (p<0.001) a marginally higher scholastic performance and marginally higher growth performance of MDM children. CONCLUSION: MDM program is associated with a better educational and nutritional status of school children in Karnataka.

Child↗
PubMed1998

The beta protein of phage lambda promotes strand exchange.

Bacteriophage lambda encodes a 28 kDa protein called beta that binds to single-stranded DNA and promotes the renaturation of complementary single strands. beta Protein fails to bind directly to duplex DNA but remains bound to the DNA product of renaturation that beta itself catalyzes. These observations led to an examination of the ability of beta protein to promote strand exchange. beta Protein caused the replacement of a 43-mer oligonucleotide annealed to M13 circular single-stranded DNA by a homologous 63-mer whose 20 extra nucleotide residues were complementary to the adjacent 3' region of M13 DNA. The role of beta protein in this reaction was manifested in several ways: beta protein pushed the exchange through four to eight mismatches, which blocked exchange mediated by spontaneous renaturation and branch migration; beta imposed a polarity on the strand exchange that was lacking in the spontaneous reaction; and beta remained bound to the heteroduplex product of strand exchange. These observations reveal a mechanism by which a protein can drive strand exchange in one direction without using ATP or any other exogenous source of energy.

Bacteriophage M13↗
PubMed1998

The beta protein of phage lambda binds preferentially to an intermediate in DNA renaturation.

Phage lambda encodes two recombination proteins that are required for homologous recombination in a recA- host strain. Of these two recombination proteins, one is an exonuclease whose action on double-stranded DNA produces 3' single-stranded ends; the other, called beta protein, is a DNA binding protein that promotes the renaturation of complementary single strands. The enzymes of phage lambda provide a model for understanding a recombination pathway called "single-strand annealing". Further investigation of the binding of beta protein to DNA has revealed a new mechanism of renaturation. As reported before, beta protein binds directly to single-stranded DNA, but not to double-stranded DNA. However, in the experiments reported here, we observed that beta protein bound more strongly to a presumed intermediate in the renaturation reaction that beta itself catalyzed, and beta thereby protected all of a renatured duplex 83-mer oligonucleotide from nuclease digestion.

Bacteriophage lambda↗
PubMed1998

Horner's syndrome following internal jugular vein cannulation.

We present two cases of Horner's syndrome occurring following uncomplicated internal jugular venous cannulation. An awareness of this potential complication will reduce confusion over the aetiology of anisocoria in critically ill patients. This consideration is important, since lesions in the central nervous system or carotid dissection following trauma might otherwise be suspected.

Adult↗
PubMed1998

Is eye padding routinely necessary after uncomplicated phacoemulsification?

PURPOSE: To investigate the value of eye padding following uncomplicated phacoemulsification under peribulbar anaesthesia. METHODS: A prospective randomised controlled study was conducted to compare the effect of a conventional eye pad and shield with that of a clear eye shield applied without a pad in 83 patients undergoing routine phacoemulsification under peribulbar anaesthesia without lid block. The primary outcome measures were corneal fluorescein staining, discomfort, diplopia and mobility. RESULTS: Moderate or severe corneal fluorescein staining on the first post-operative day was significantly more common in the pad and shield group (39%) than in the clear shield group (19%) (p < 0.01). There was no significant difference in post-operative pain as measured either by visual analogue scale or by categorical pain scale. Forty per cent of the clear shield group reported transient post-operative diplopia during the immediate post-operative period compared with 7% of the pad and shield group (p < 0.001). There was no significant difference in reported mobility between the two groups. CONCLUSIONS: Following phacoemulsification under peribulbar anaesthesia, the use of a gauze eye pad is associated with greater corneal fluorescein staining than a clear plastic shield without pad and offers no reduction in discomfort. A clear shield protects the globe against direct trauma, is associated with reduced moderate to severe corneal staining and facilitates vision in the early post-operative period. Transient diplopia reported by some patients given a clear shield is not disabling and would not be expected to occur in patients with one seeing eye. The use of a clear shield alone is a safe alternative to eye padding and offers important advantages in patients with one seeing eye.

Aged↗
PubMed1997

Assessment of environmental hazards of 1,3,5-trinitrobenzene.

The remedial investigation/feasibility studies conducted at certain Army installations showed a need to clean up contaminated sites, where high levels of ammunition chemicals such as 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), 1,3-dinitrobenzene (DNB), and their degradation products/metabolites were detected in surface soil and groundwater. TNB is a photodegradation product of TNT; it is not easily degraded, and persists in the environment. The toxicity data on TNB are scanty. Hence the U.S. Environmental Protection Agency in 1988 (U.S. EPA, 1997) developed a reference dose (RfD) for TNB (0.00005 mg/kg/d for chronic toxicity) based on the toxicity of DNB, which is structurally similar to TNB. Since then we have completed acute, subacute, subchronic, chronic, reproductive, and developmental toxicity studies and toxicokinetics studies. We have reviewed the mammalian toxicity data for TNB and have determined the no observed adverse effect levels (NOAEL) and low observed adverse effect levels (LOAEL) for subchronic, chronic, reproductive, and developmental toxicity. Based on the newly determined NOAEL and LOAEL values, we have now developed a new RfD for TNB (0.03 mg/kg/d), based on the chronic toxic effects on hematology and histopathological changes in testes and kidney.

Administration, Oral↗
PubMed1997

Human Rad52 protein promotes single-strand DNA annealing followed by branch migration.

In the yeast, Saccharomyces cerevisiae, the Rad52 gene is important for both mitotic and meiotic recombination. Homologs of the Rad52 gene have been identified in several eukaryotic organisms, ranging from yeast to man. As reported here, human Rad52 protein binds to both single- and double-stranded DNA; and acting on a pair of single-stranded and partially duplex substrates it promotes annealing of complementary strands of DNA, which is followed by branch migration.

Cloning, Molecular↗
PubMed1997

Testicular effects of 1,3,5-trinitrobenzene (TNB). I. Dose response and reversibility studies.

Testicular effects of TNB were characterized after single and multiple oral doses of TNB at 0, 35.5, and 71 mg/kg. Male Fischer 344 (F344) rats were killed after a single dose or after 4 and 10 daily doses of TNB. Testicular effects were not evident at the light microscope level in rats killed after a single dose of TNB or after 4 daily doses at 35.5 mg/kg of TNB. Rats receiving 4 daily doses of TNB at 71 mg/kg had the earliest evidence of testicular damage, with necrosis and degeneration of pachytene spermatocytes including a significant decrease in testicular weight. Rats dosed at 35.5 mg/kg for 10 d had severe testicular lesions, in addition to the decrease in testicular weight. There was degeneration of round and elongate spermatids, and formation of multinucleate syncytial cells. The epididymis was devoid of sperm, instead containing exfoliated syncytial spermatids. Rats dosed at 71 mg/kg of TNB for 10 d had testicular atrophy and cessation of spermatogenesis. These rats also had apoptic cells in the ventral prostate. To assess the extent of reversibility in these atrophied testis, rats were allowed to recover for 10 or 30 d after 10 doses of TNB (71 mg/kg). A significant regenerative attempt with proliferating spermatocytes were present at 10 d and elongate spermatids were evident at 30 d. These reversibility studies indicate testicular effects of TNB are at least partially reversible.

Animals↗
PubMed1997

Testicular effects of 1,3,5-trinitrobenzene (TNB). II. Immunolocalization of germ cells using proliferating cell nuclear antigen (PCNA) as an endogenous marker.

The applicability of PCNA as a tool for the analysis of germ cells in rats treated with 1,3,5-trinitrobenzene (TNB), a potent testicular toxicant, was evaluated. Male Fischer 344 (F344) rats were gavaged with TNB at 71 mg/kg or with corn oil (vehicle). Rats were killed after 10 daily oral doses or were allowed to recover for 10 or 30 d after the 10 doses. Testes from control rats, treated rats, and rats allowed to recover were immunohistochemically stained for PCNA. PCNA labeling in the control rats was confined to the nuclei of spermatogonia, pachytene spermatocytes, and nuclei of elongate spermatocytes. Conventional (hematoxylin and eosin) staining of testes from rats treated with TNB at 71 mg/kg for 10 d revealed loss of germ cells and cessation of spermatogenesis. Immunohistochemical staining of sections from these treated rats revealed only PCNA-positive spermatogonia. Rats allowed a 10-d recovery had both spermatogonial and spermatocytic staining, indicating partial restoration of germ-cell population. In rats allowed to recover for 30 d, the PCNA staining pattern was identical to the control rats. These results indicate that PCNA can be used to assess the proliferative status of spermatogonia (germ cells) in rodent testes exposed to testicular toxicants.

Animals↗
PubMed1996

Rad51 expression and localization in B cells carrying out class switch recombination.

Rad51 is a highly conserved eukaryotic homolog of the prokaryotic recombination protein RecA, which has been shown to function in both recombinational repair of DNA damage and meiotic recombination in yeast. In primary murine B cells cultured with lipopolysaccharide (LPS) to stimulate heavy chain class switch recombination, Rad51 protein levels are dramatically induced. Immunofluorescent microscopy shows that anti-Rad51 antibodies stain foci that are localized within the nuclei of switching B cells. Immunohistochemical analysis of splenic sections shows that clusters of cells that stain brightly with anti-Rad51 antibodies are evident within several days after primary immunization and that Rad51 staining in vivo is confined to B cells that are switching from expression of IgM to IgG antibodies. Following switch recombination, B cells populate splenic germinal centers, where somatic hypermutation and clonal proliferation occur. Germinal center B cells are not stained by anti-Rad51 antibodies. Rad51 expression is therefore not coincident with somatic hypermutation, nor does Rad51 expression correlate simply with cell proliferation. These data suggest that Rad51, or a highly related member of the conserved RecA family, may function in class switch recombination.

Amino Acid Sequence↗
PubMed1996

Extensive sequencing of tryptic peptides of a rabbit reticulocyte 66-kDa protein that promotes recycling of Hsp 70. Homology To stress-related proteins.

Trypsinization and sequence analysis of the 66-kDa rabbit reticulocyte protein (RF-hsp 70), shown in the preceding article to function as a recycling protein for hsp 70, demonstrates striking similarity to the transformation-sensitive human protein IEF SSP 3521 (Honoré, B., Leffers, H., Madsen, P., Rasmussen, H. H., Vandekerckhove, J., and Celis, J. E.(1992) J. Biol. Chem. 267, 8485-8491) and mouse extendin (Blatch, G. L., Lassle, M., Takatori, T., Gandhi, T., Kundra, V., and Zetter, B. R.(1995) Proc. Am. Assoc. Cancer Res. 36, 68). The human and mouse proteins share 97% sequence identity, and sequencing of 20 polypeptides (225 residues) from RF-hsp 70 reveals only 10 differences between the rabbit and human proteins and 13 differences between the rabbit and mouse proteins (96 and 94% identity, respectively). In addition, all three proteins are of similar size, and each contains 11 cysteines. These findings strongly suggest that these three proteins are homologs of the same activity. All differences (but one) between the human and mouse proteins occur within the amino-terminal half of the protein, and there is only one difference among 121 sequenced residues between RF-hsp 70 and the human or mouse protein which occurs within the carboxyl-terminal 70% of the molecule. In addition, where partial sequences of RF-hsp 70 and p60, a chick oviduct protein that shows 70% identity to the human protein (Smith, D. F., Sullivan, W. P., Marion, T. N., Zaitsu, K., Madden, B., McCormick, D. J., and Toft, D. O. (1993) Mol. Cell. Biol. 13, 869-876), overlap (a total of 54 residues), RF-hsp 70 and chick p60 show 78% sequence identity. Studies of the initial digestion of RF-hsp 70 by trypsin indicate that it is first converted to 58- and 54-kDa components, each of which is then converted to a 43-kDa polypeptide. This 43-kDa component is located in the human and mouse proteins at position 124 to about 470. It is converted subsequently to a 31-kDa polypeptide by trypsin hydrolysis at position 207. This 31-kDa component is finally split into 17- and 14-kDa polypeptides that are located at positions 208 to approximately 351 and 352 to approximately 470, respectively. The 14-kDa polypeptide is relatively resistant to further digestion with trypsin, and seven tryptic peptides from other parts of RF-hsp 70 contain internal lysine and/or arginine residues (as do several tryptic peptides produced from IEF SSP 3521 and chick p60). Both features may be due to interference with trypsin action by secondary structure in the protein, since trypsinization of reduced and carboxymethylated RF-hsp 70 results in hydrolysis of the 14-kDa polypeptide and reduces the level of peptides that contain internal lysine and/or arginine, although it does not eliminate them.

Amino Acid Sequence↗
PubMed1996

Presynaptic association of Rad51 protein with selected sites in meiotic chromatin.

Eukaryotic homologs of Escherichia coli Rec-A protein have been shown to form nucleoprotein filaments with single-stranded DNA that recognize homologous sequences in duplex DNA. Several recent reports in four widely diverse species have demonstrated the association of RecA homologs with meiotic prophase chromatin. The current immunocytological study on mouse spermatocytes and oocytes shows that a eukaryotic homolog, Rad5l, associates with a subset of chromatin sites as early as premeiotic S phase, hours before either the appearance of precursors of synaptonemal complexes or the initiation of synapsis. When homologous chromosomes do begin to pair, the Rad5l-associated sequences are sites of initial contact between homologues and of localized DNA synthesis. Distribution of Rad5l foci on the chromatin of fully synapsed bivalents at early pachynema corresponds to an R-band pattern of mitotic chromosomes. R-bands are known to be preferred sites of both synaptic initiation and recombination. The time course of appearance of Rad51 association with chromatin, its distribution, and its interaction with other Rad5l-associated sequences suggests that it plays an important role preselection of sequences and synaptic initiation.

Animals↗
PubMed1996

Loss of contrast intensity during systole in the left ventricular cavity with the use of the contrast agent Albunex. An analysis of its correlation with pressure and velocity.

RATIONALE AND OBJECTIVES: Several investigators have observed a decrease in video intensity in the left ventricular cavity during systole when using contrast echocardiography. It has been suggested that this phenomenon is related to microbubble instability. The authors propose that this phenomenon is, in part, related to the effects of pressure and velocity on the acoustic reflectance of ultrasound contrast agents. METHODS: Using an in vitro flow tube model and varying concentrations of Albunex contrast agent, the effects of pressure and velocity on microbubble video intensity were investigated. Velocity and pressure were varied independently and the imaging tube was scanned using three transducer frequencies at different concentrations of Albunex. Contrast video intensity was analyzed using high and low velocities (at constant pressure) and high and low pressures (at constant velocity). In addition, the fluid from the system was collected and imaged in a nonflowing reservoir tank to investigate the video intensity of the microbubbles when exposed to variable velocity and pressure. RESULTS: The video-intensity measurements were inversely and irreversibly related to ambient pressure changes (independent of velocity) in a tube model. However, video intensity varied inversely but reversibly with velocity (independent of pressure). This observation could not be explained simply by the "laminar flow" theory, by a change in transducer angulation, nor by a change in ultrasound imaging frame rate. This phenomenon was limited to Albunex microbubbles and was not observed with a contrast medium (corn starch) devoid of the acoustic properties of Albunex.

Albumins↗
PubMed1995

Lysine residues at positions 234 and 236 in yeast porin are involved in its assembly into the mitochondrial outer membrane.

Various point mutations of lysyl residues in yeast mitochondrial porin (283 residues) were tested for their ability to assemble in vitro into the outer membranes of intact yeast mitochondria. Assembly was evaluated by protection from proteinases. The extent of assembly of two of the mutants, K234E and K236E porins, was much less than for wild-type in either post-translational or co-translational assembly assays. Lysine to glutamate mutants at other positions and K234R porin assembled as well as wild-type, but K234Q porin was poorly inserted. When both Lys-234 and Lys-236 were mutated, K234R/K236R porin was inserted better than K234Q/K236Q porin, which was inserted better than K234E/K236E; however, none of these mutants assembled as well as wild-type porin. It was concluded that optimal assembly of yeast porin depended on the presence of positively charged residues at both positions 234 and 236 and a lysine at one of these positions. After undergoing the assembly reaction, mutants that were vulnerable to proteinase K (i.e. K234E, K234Q, and K236E porins) seemed to be incompletely digested and were, to varying degrees, resistant to extraction by Na2CO3 (pH 11.5). These experiments suggested that these mutants were incompletely inserted into the outer membrane. Both Lys-234 and Lys-236 are included in an internal pentapeptide, VKAKV, that is conserved in porins from protists, plants, and animals, and it is possible that, at least, the lysines in this tract are one of the signals for the membrane assembly of these proteins.

Amino Acid Sequence↗
PubMed1995

Uptake and processing of duplex DNA by RecA nucleoprotein filaments: insights provided by a mixed population of dynamic and static intermediates.

In the polarized strand exchange that is promoted by Escherichia coli RecA protein, when the initiating end of a duplex DNA molecule is blocked by heterology, the homologous distal end nonetheless forms a joint with single-stranded DNA, but strand exchange in that joint cannot be completed because the strand that would otherwise be displaced lacks a free 5' end. Instead, 2/3 to 3/4 of such distal joints cyclically form and dissociate. Dissociation requires the hydrolysis of ATP (Burnett et al., 1994). Observations on DNase protection revealed that consistent with their dynamic nature, these joints were heterogeneous in length, extending from the labeled distal end of the duplex up to 600 base pairs within the homologous region. Switching of base pairs was undetectable in this fraction of distal joints. However, the other 1/3 to 1/4 of distal joints, which did not cycle, were as long as the entire homologous region (6 kb), and underwent complete switching of base pairs. The formation of these static joints occurred at a rate in excess of 100 bp per second, without requiring hydrolysis of ATP. These and earlier observations suggest that the RecA filament containing single-stranded DNA rapidly incorporates duplex DNA into a coaxial three-stranded helix by a passive process, whereas additional energy is required to convert the three-stranded intermediate into products or back into substrates, both of which involve the unwinding of many turns of three-stranded helix.

Adenosine Triphosphate↗
PubMed1995

Dinitrobenzene induces methemoglobin formation from deoxyhemoglobin in vitro.

The reaction of hemoglobin (Hb) with dinitrobenzenes (DNBs) was studied to develop a molecular-level understanding of such reactions that will enhance the development of toxicokinetic models that employ Hb adducts as biomarkers for exposure. Methemoglobin (metHb) is formed during the reaction and UV/VIS spectroscopy was used to follow the reaction of DNB isomers with deoxy-(dxHb), oxy-(HbO2) and carboncarboxy-(HbCO) hemoglobin. HPLC chromatography of dxHb treated with radiolabelled DNB was employed to detect possible adduct formation. Deconvolution of the spectra and the presence of well-defined isobestic points imply that DNB induces a direct conversion of dxHb to metHb, but little or no conversion occurs for either HbCO or HbO2. This implies that the reaction of DNB with Hb may require direct access to the heme and/or that the reaction is initiated by oxidation of the heme, which occurs more readily in the deoxy state. Labelled DNB formed no detectable covalent Hb adducts in the presence of dxHb, providing evidence that metHb formation is not linked to adduct formation.

Animals↗
PubMed1995

Nuclear foci of mammalian Rad51 recombination protein in somatic cells after DNA damage and its localization in synaptonemal complexes.

Rad51 protein of Saccharomyces cerevisiae is a structural homolog of the Escherichia coli recombination enzyme RecA. In yeast, the Rad51 protein is required for mitotic and meiotic recombination and for repair of double-strand breaks in DNA. We have used antibodies raised against the homologous human protein, HsRad51, expressed in E. coli, to visualize the spatial distribution of the protein in mammalian somatic and meiotic cells. In cultured human cells, the HsRad51 protein is concentrated in multiple discrete foci in the nucleoplasm; it is largely absent from cytoplasm and nucleoli. After treatment of cells with methyl methanesulfonate, ultraviolet irradiation, or 137Cs irradiation, the percentage of cells with HsRad51 protein immunofluorescence increases; the same cells show unscheduled DNA synthesis. Induction of Rad51 foci is blocked by inhibitors of transcription. In mouse pachytene spermatocytes, the mouse homolog of Rad51 protein is highly enriched in synaptonemal complexes that are formed between the paired homologous chromosomes during meiotic prophase. We conclude that the mammalian proteins homologous to yeast Rad51 are involved in repair of DNA damage and recombinational repair during meiosis.

Animals↗