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S Misra

Publications and source records attributed to S Misra.

At least 55 records · Page 3Linked to original sources
PubMed2000

Regulation of NADPH-cytochrome P450 reductase expressed during Douglas-fir germination and seedling development.

NADH-cytochrome P450 is a key enzyme that transfers electrons from NADPH to the cytochrome P450 family of enzymes. To begin to determine the regulation of CPR gene expression and enzyme activity in Douglas-fir a full-length cDNA was isolated from a seedling lambda ZAP cDNA library and the ORF was used to develop a synthetic CPR-peptide-based antiserum. Northern blot analysis indicated CPR expression was regulated both developmentally prior to seed maturation and during germination, and differentially in the cotyledons, radicle and megagametophyte of seed and seedling tissues. The CPR-peptide antiserum detected a single CPR in seed and seedling microsomes analyzed by western blot of two-dimensional SDS-polyacrylamide gels. In microsomal extracts from whole seeds and seedlings, the amount of CPR protein remained constant while NADPH:cytochrome c reductase activity increased during stratification, germination and early seedling development. In contrast to cotyledons and megagametophyte, the level of CPR protein detected in radicles was higher than expected when compared to the amount of CPR transcript.

Amino Acid Sequence↗
PubMed2000

Transgenic plants expressing cationic peptide chimeras exhibit broad-spectrum resistance to phytopathogens.

Here we describe a strategy for engineering transgenic plants with broad-spectrum resistance to bacterial and fungal phytopathogens. We expressed a synthetic gene encoding a N terminus-modified, cecropin-melittin cationic peptide chimera (MsrA1), with broad-spectrum antimicrobial activity. The synthetic gene was introduced into two potato (Solanum tuberosum L.) cultivars, Desiree and Russet Burbank, stable incorporation was confirmed by PCR and DNA sequencing, and expression confirmed by reverse transcription (RT)-PCR and recovery of the biologically active peptide. The morphology and yield of transgenic Desiree plants and tubers was unaffected. Highly stringent challenges with bacterial or fungal phytopathogens demonstrated powerful resistance. Tubers retained their resistance to infectious challenge for more than a year, and did not appear to be harmful when fed to mice. Expression of msrA1 in the cultivar Russet Burbank caused a striking lesion-mimic phenotype during leaf and tuber development, indicating its utility may be cultivar specific. Given the ubiquity of antimicrobial cationic peptides as well as their inherent capacity for recombinant and combinatorial variants, this approach may potentially be used to engineer a range of disease-resistant plants.

Amino Acid Sequence↗
PubMed2000

A topographic study of Helicobacter pylori density, distribution and associated gastritis.

BACKGROUND AND AIMS: The topographic distribution and density of Helicobacter pylori and associated gastritis in the stomach were studied in order to determine which biopsy sites are likely to provide the maximum yield so as to reduce the fallacious results due to sampling error. METHODS: Fifty patients with upper gastrointestinal symptoms were studied. Eleven gastric biopsies from predetermined sites were obtained and subjected to ultra-rapid urease test, imprint cytology and histology. Haematoxylin and eosin stain was used for defining gastritis and other associated histopathological details. Loeffler's methylene blue stain was used to confirm the presence of H. pylori in imprint smears and histological sections. RESULTS: All 50 patients had H. pylori infection and evidence of chronic gastritis at one or more of the 11 biopsy sites. Maximum and minimum percentage positivity were observed at A3 (antral lesser curvature) and B4 (corpus greater curvature), respectively. Various sites in decreasing order of percentage positivity were A3 > A2 > A1 > A4 > B3 > B1 > A5 > B6 > B5 > B2 > B4. Among the biopsies obtained from the corpus, B3 (corpus lesser curvature) was the site with maximum positivity. A3 and B4 had a statistically significant difference in percentage positivity (P < 0.0001) for H. pylori and gastritis. The maximum and minimum density scores of H. pylori and gastritis were found in A3 and the B4, respectively. A3 had a significantly higher (P < 0.0001) mean density score than any other site in the stomach. The difference in the grading of H. pylori between A3 and B3 (sites of maximum positivity in antrum and corpus) was statistically significant (P < 0.0001). A statistically significant (P < 0.001) positive correlation between increasing grades of H. pylori and gastritis was observed at the site of maximum density. Eighty per cent of the patients had antral predominant gastritis and in 82%, H. pylori was predominantly observed in antral biopsies. CONCLUSION: It is concluded that two biopsies taken from A3 are sufficient for confirmation of presence of H. pylori and associated gastritis for initiation of treatment. However, additional biopsies from B3 will help in deciding the topographic pattern of gastritis.

Adult↗
PubMed2000

Overexpression of p53 protein in gallbladder carcinoma in North India.

AIMS: p53 mutations are one of the most frequent genetic alterations in human cancers and are thought to play a role in pathogenesis of several malignancies. Overexpression of p53 in gallbladder cancer has not previously been reported from North India which has one of the highest incidence of this malignancy in the world. The present work is aimed at studying the overexpression of p53 in gallbladder carcinoma occurring in North India. METHODS: p53 overexpression by immunohistochemistry was studied in 20 operative specimens of gallbladder carcinoma. The clinico-pathological observations of these patients were correlated with the extent of p53 overexpression. RESULTS: Seventy per cent (14/20) of specimens of gallbladder carcinoma overexpressed p53 protein. There was a significant correlation between presence of gallstones, T stage, grade of tumour and liver invasion with p53 overexpression. There was no significant correlation with other factors studied viz. age, sex, nodal status and histological type. CONCLUSIONS: The results show a strong association between gallstones and p53 protein overexpression in gallbladder carcinoma. The causal relationship in this association, however, still remains unproven.

Adult↗
PubMed2000

Altered diurnal regulation of blood ionized calcium and serum parathyroid hormone concentrations during parenteral nutrition.

BACKGROUND: Little is known about parathyroid gland function in patients receiving total parenteral nutrition (TPN). OBJECTIVE: Our objective was to determine whether parathyroid gland function is abnormal in TPN recipients. DESIGN: Six patients with a mean (+/-1 SD) age of 45.5 +/- 8.0 y who had been receiving TPN for 18.7 +/- 2. 8 y underwent bone biopsy, bone mass measurements with dual-energy X-ray absorptiometry, and dynamic tests of parathyroid gland function. Diurnal variations in blood ionized calcium (iCa(2+)) and serum parathyroid hormone (PTH) concentrations were also assessed. Results were compared with those of healthy volunteers. RESULTS: Bone mass and bone formation were subnormal in all patients. Basal serum PTH concentrations were moderately higher in the TPN recipients than in healthy volunteers, and values obtained every 30 min over 24 h were significantly higher (P < 0.001) in TPN recipients (5.0 +/- 0.9 pmol/L) than in healthy volunteers (2.6 +/- 0.6 pmol/L). The percentage increase in serum PTH during citrate-induced hypocalcemia was lower in the TPN recipients, consistent with secondary hyperparathyroidism. Evening infusions of calcium-containing TPN eliminated the nocturnal rise in serum PTH, increased the amplitude of change for iCa(2+) and PTH over 24 h, increased the orderliness of change for iCa(2+) and PTH as measured by approximate entropy (ApEn), and enhanced the synchrony of change between iCa(2+) and PTH. Treatment for 10 d with calcium-free TPN restored the nocturnal rise in serum PTH and increased ApEn for PTH. ApEn for iCa(2+) remained low, suggesting that a component of nutrient solutions, but not calcium per se, enhances the regularity of PTH release in TPN recipients. CONCLUSION: Parathyroid gland function is abnormal in long-term TPN recipients, which may contribute to disturbances in bone metabolism.

Adult↗
PubMed2000

Signaling and subcellular targeting by membrane-binding domains.

Protein kinase C homology-1 and -2, FYVE, and pleckstrin homology domains are ubiquitous in eukaryotic signal transduction and membrane-trafficking proteins. These domains regulate subcellular localization and protein function by binding to lipid ligands embedded in cell membranes. Structural and biochemical analysis of these domains has shown that their molecular mechanisms of membrane binding depend on a combination of specific and nonspecific interactions with membrane lipids. In vivo studies of green fluorescent protein fusions have highlighted the key roles of these domains in regulating protein localization to plasma and internal membranes in cells.

Amino Acid Sequence↗
PubMed2000

Cytogenetic toxicity of cisplatin in bone marrow cells of Swiss mice.

The inorganic platinum compound cisplatin (CP) in Oncoplatin, an anticancer drug, as the test chemical and cyclophosphamide (CY) in Endoxan, another anticancer drug, as the positive control, were tested for their cytogenetic toxicity in bone marrow cells of Swiss mice. The end points selected were mitotic metaphase chromosomal aberration and mitotic index study at 24-hour post-treatment and micronucleus test at 30-hour post-treatment after a single intraperitoneal exposure. The doses of the chemicals tested were CP 2, 3 and 5 mg/kg and CY 40 mg/kg b.w. of mice. Each of the doses of CP induced a significant number of chromosomal aberrations, mostly chromatid breaks and fragments and a significant number of micronuclei. The mitotic index study indicated CP as nonmitotoxic. The female mice were found more sensitive to each of the doses of CP than the males by showing more chromosomal aberrations, a higher number of micronuclei and comparatively less percentages of dividing cells. CP was thus found to be highly clastogenic in bone marrow cells of Swiss mice.

Animals↗
PubMed2000

Potential transmission of the cytogenetic effects of cisplatin in the male germline cells of Swiss mice.

Cisplatin (CP) (in Oncoplatin), a widely used drug in cancer chemotherapy, and cyclophosphamide (CY) (in Endoxan), another anticancer drug, were investigated as the test chemical and positive control, respectively, for their cytogenetic effects on spermatogonia of mice at 24 hours post-treatment after a single exposure. The different doses of the chemicals tested were CP 2, 3, 5 mg/kg and CY 40 mg/kg b.w. of mice. Each of the doses of CP induced a significant number of chromosomal aberrations, mostly chromatid breaks and fragments. The potential transmission of such cytogenetic effects of the chemicals from spermatogonia to spermatocytes was assessed at week 4 post-treatment from the primary spermatocytes, which showed a significant number of aberrant spermatocytes with atypical bivalents viz. spermatocytes with autosomal and/or XY univalents, tetravalents and with extra elements. The probable causes of the formation of univalents and tetravalents are discussed. The transmission of the cytogenetic effects of the chemicals from spermatogonia up to sperm was assessed at week 8 post-treatment from the morphology of sperm collected from vas. Quantitatively the transmission of such effects was found decreased substantially by the time the exposed spermatogonia became sperm. Still there was the occurrence of a few abnormal sperm at week 8 post-treatment. The probable causes of the quantitative decrease in the transmission of the effects from spermtogonia to sperm are discussed.

Animals↗
PubMed2000

Pathological laughter as heralding manifestation of left middle cerebral artery territory infarct: case report and review of literature.

Clinical, radiological and pathological studies in patients with stroke, presenting with pathological laughter as heralding manifestation, have shown lesions in the internal capsule and thalamus, basal ganglion, hypothalamus and ventral pons. In this report a patient with similar manifestation and having a cortical infarct in the territory supplied by superior division of middle cerebral artery is being presented. Our case suggests possible influence of dominant cerebral hemisphere, especially of Broca's area, on the motor control of laughter.

Dominance, Cerebral↗
PubMed2000

Cytogenetic toxicity of vincristine.

The anticancer drugs vincristine sulphate (VCR) and cyclophosphamide (CTX) were tested for their cytogenetic effects in the bone marrow cells of Swiss mice. The end points investigated were chromosomal aberrations and mitotic index at 24 hours posttreatment and micronuclei (MN) at 30 hours posttreatment in bone marrow cells of male and female mice after a single intraperitoneal exposure. The doses tested were VCR 0.25, 0.5, and 1.0 mg/kg and CTX 40 mg/kg b.w. of mice. Significant percentages of chromosomal aberrations and significant numbers of micronuclei per thousand polychromatic erythrocytes (PCEs) that were induced were recorded from bone marrow of each of the VCR-treated groups of mice. There were no significant differences between the percentages of dividing cells in the VCR-treated group and the vehicle control groups of mice. Peculiarly, in the chromosomal aberration study, the male mice were found to be more responsive to VCR than the females, and the aberrations per hundred metaphases were found to be decreased when the dose of VCR was increased. The percentage of dividing cells was also higher with the lowest dose of VCR tested. However, there was a dose-dependent, but nonlinear, increase in MN per thousand PCEs. The results were compared with the already available fragmentary and self-contradictory data on the genotoxicity of VCR in mice and in other mammalian test systems.

Animals↗
PubMed2000

Non-epileptic manifestations in patients with single enhancing computed tomography lesions.

OBJECTIVES AND METHODS: Single enhancing lesions are common computed tomographic (CT) abnormality in patients with epilepsy. In this series we are reporting 13 unusual cases with varied non-epileptic neurological manifestations in patients with ring or disk enhancing CT lesions. RESULTS: Acute, stroke like non-vascular focal neurological deficits (hemiparesis in four patients, and crural monoparesis, Broca's aphasia, homonymous hemianopia, hemichorea in one patient each) were frequent non-epileptic manifestations. Episodic vascular type of headache was seen in three patients, one patient had headache because of raised intracranial pressure. One patient presented with acute confusional state. All these patients were treated symptomatically, and with oral corticosteroids. CT lesions disappeared in 8-12 weeks time in all patients except in one patient with chorea where the lesion calcified. Significant clinical improvements were noted in all the patients. CONCLUSIONS: Several non-epileptic manifestations can also be associated with single enhancing CT lesions, and like epileptic disorders these disorders also have a benign course. Corticosteroids, probably, hasten the clinical improvement and produce early resolution of the CT lesions.

Adolescent↗
PubMed1999

Crystal structure of a phosphatidylinositol 3-phosphate-specific membrane-targeting motif, the FYVE domain of Vps27p.

Phosphatidylinositol 3-phosphate regulates membrane trafficking and signaling pathways by interacting with the FYVE domains of target proteins. The 1.15 A structure of the Vps27p FYVE domain reveals two antiparallel beta sheets and an alpha helix stabilized by two Zn2+-binding clusters. The core secondary structures are similar to a rabphilin-3A Zn2+-binding domain and to the C1 and LIM domains. Phosphatidylinositol 3-phosphate binds to a pocket formed by the (R/K)(R/K)HHCR motif. A lattice contact shows how anionic ligands can interact with the phosphatidylinositol 3-phosphate-binding site. The tip of the FYVE domain has basic and hydrophobic surfaces positioned so that nonspecific interactions with the phospholipid bilayer can abet specific binding to phosphatidylinositol 3-phosphate.

Amino Acid Sequence↗
PubMed1999

Phosphoinositide 3-kinase lipid products regulate ATP-dependent transport by sister of P-glycoprotein and multidrug resistance associated protein 2 in bile canalicular membrane vesicles.

Bile acid transport and secretion in hepatocytes require phosphatidylinositol (PI) 3-kinase-dependent recruitment of ATP-dependent transporters to the bile canalicular membrane and are accompanied by increased canalicular PI 3-kinase activity. We report here that the lipid products of PI 3-kinase also regulate ATP-dependent transport of taurocholate and dinitrophenyl-glutathione directly in canalicular membranes. ATP-dependent transport of taurocholate and dinitrophenyl-glutathione in isolated canalicular vesicles from rat liver was reduced 50-70% by PI 3-kinase inhibitors, wortmannin, and LY294002, at concentrations that are specific for Type I PI 3-kinase. Inhibition was reversed by addition of lipid products of PI 3-kinase (PI 3,4-bisphosphate and, to a lesser extent, PI 3-phosphate and PI 3,4,5-trisphosphate) but not by PI 4, 5-bisphosphate. A membrane-permeant synthetic 10-mer peptide that binds polyphosphoinositides and leads to activation of PI 3-kinase in macrophages doubled PI 3-kinase activity in canalicular membrane vesicles and enhanced taurocholate and dinitrophenyl-glutathione transport in canalicular membrane vesicles above maximal ATP-dependent transport. The effect of the peptide was blocked by wortmannin and LY294002. PI 3-kinase activity was also necessary for function of the transporters in vivo. ATP-dependent transport of taurocholate and PI 3-kinase activity were reduced in canalicular membrane vesicles isolated from rat liver that had been perfused with taurocholate and wortmannin. PI 3,4-bisphosphate enhanced ATP-dependent transport of taurocholate in these vesicles above control levels. Our results indicate that PI 3-kinase lipid products are necessary in vivo and in vitro for maximal ATP-dependent transport of bile acid and nonbile acid organic anions across the canalicular membrane. Our results demonstrate regulation of membrane ATP binding cassette transporters by PI 3-kinase lipid products.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

Chloride binding regulates the Schiff base pK in gecko P521 cone-type visual pigment.

The binding of chloride is known to shift the absorption spectrum of most long-wavelength-absorbing cone-type visual pigments roughly 30 nm to the red. We determined that the chloride binding constant for this color shift in the gecko P521 visual pigment is 0.4 mM at pH 6.0. We found an additional effect of chloride on the P521 pigment: the apparent pKa of the Schiff base in P521 is greatly increased as the chloride concentration is increased. The apparent Schiff base pKa shifts from 8.4 for the chloride-free form to >10.4 for the chloride-bound form. We show that this shift is due to chloride binding to the pigment, not to the screening of the membrane surface charges by chloride ions. We also found that at high pH, the absorption maximum of the chloride-free pigment shifts from 495 to 475 nm. We suggest that the chloride-dependent shift of the apparent Schiff base pKa is due to the deprotonation of a residue in the chloride binding site with a pKa of ca. 8.5, roughly that of the Schiff base in the absence of chloride. The deprotonation of this site results in the formation of the 475 nm pigment and a 100-fold decrease in the pigment's ability to bind chloride. Increasing the concentration of chloride results in the stabilization of the protonated state of this residue in the chloride binding site and thus increased chloride binding with an accompanying increase in the Schiff base pK.

Animals↗
PubMed1999

The Berkeley Drosophila Genome Project gene disruption project: Single P-element insertions mutating 25% of vital Drosophila genes.

A fundamental goal of genetics and functional genomics is to identify and mutate every gene in model organisms such as Drosophila melanogaster. The Berkeley Drosophila Genome Project (BDGP) gene disruption project generates single P-element insertion strains that each mutate unique genomic open reading frames. Such strains strongly facilitate further genetic and molecular studies of the disrupted loci, but it has remained unclear if P elements can be used to mutate all Drosophila genes. We now report that the primary collection has grown to contain 1045 strains that disrupt more than 25% of the estimated 3600 Drosophila genes that are essential for adult viability. Of these P insertions, 67% have been verified by genetic tests to cause the associated recessive mutant phenotypes, and the validity of most of the remaining lines is predicted on statistical grounds. Sequences flanking >920 insertions have been determined to exactly position them in the genome and to identify 376 potentially affected transcripts from collections of EST sequences. Strains in the BDGP collection are available from the Bloomington Stock Center and have already assisted the research community in characterizing >250 Drosophila genes. The likely identity of 131 additional genes in the collection is reported here. Our results show that Drosophila genes have a wide range of sensitivity to inactivation by P elements, and provide a rationale for greatly expanding the BDGP primary collection based entirely on insertion site sequencing. We predict that this approach can bring >85% of all Drosophila open reading frames under experimental control.

Alleles↗
PubMed1999

An exploration of the sequence of a 2.9-Mb region of the genome of Drosophila melanogaster: the Adh region.

A contiguous sequence of nearly 3 Mb from the genome of Drosophila melanogaster has been sequenced from a series of overlapping P1 and BAC clones. This region covers 69 chromosome polytene bands on chromosome arm 2L, including the genetically well-characterized "Adh region." A computational analysis of the sequence predicts 218 protein-coding genes, 11 tRNAs, and 17 transposable element sequences. At least 38 of the protein-coding genes are arranged in clusters of from 2 to 6 closely related genes, suggesting extensive tandem duplication. The gene density is one protein-coding gene every 13 kb; the transposable element density is one element every 171 kb. Of 73 genes in this region identified by genetic analysis, 49 have been located on the sequence; P-element insertions have been mapped to 43 genes. Ninety-five (44%) of the known and predicted genes match a Drosophila EST, and 144 (66%) have clear similarities to proteins in other organisms. Genes known to have mutant phenotypes are more likely to be represented in cDNA libraries, and far more likely to have products similar to proteins of other organisms, than are genes with no known mutant phenotype. Over 650 chromosome aberration breakpoints map to this chromosome region, and their nonrandom distribution on the genetic map reflects variation in gene spacing on the DNA. This is the first large-scale analysis of the genome of D. melanogaster at the sequence level. In addition to the direct results obtained, this analysis has allowed us to develop and test methods that will be needed to interpret the complete sequence of the genome of this species. Before beginning a Hunt, it is wise to ask someone what you are looking for before you begin looking for it. Milne 1926

Alcohol Dehydrogenase↗
PubMed1999

Endoscopic treatment of the trapped fourth ventricle

OBJECTIVE: To propose endoscopic treatment as an effective initial alternative for patients with a trapped fourth ventricle. METHODS: We reviewed the records of the last 16 consecutive patients with a symptomatic trapped fourth ventricle seen at the Arkansas Children's Hospital. The first eight patients underwent a shunt procedure; the next eight had endoscopic procedures. The shunt procedures consisted of either separate shunts or combined supra- and infratentorial shunts with shared distal catheters. The endoscopic procedures consisted of either fenestration into the lateral ventricle or aqueductal plasty with or without a stent. RESULTS: All patients underwent successful procedures with good outcomes, although the patients with shunts appeared to have a higher-than-expected rate of revision (50%). Seven revisions were performed on four patients, with a complication rate of 25%. Of the patients who had endoscopic procedures, one eventually required a shunt. The overall complication rate for patients who had endoscopic procedures was also 25%. CONCLUSION: Endoscopic treatment of the trapped fourth ventricle is effective in most cases. In view of the higher-than-expected revision rate with fourth ventricular shunts and an equivalent complication rate, endoscopic treatment is a reasonable initial treatment option for patients with a trapped fourth ventricle.

Journal Article↗