Toxicity of Chlorpyrifos to the fish Oreochromis mossambicus.
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Agriculture↗
Biomedical subjects
R N Rao
Publications and source records attributed to R N Rao.
Determination of cis and trans isomers of monocrotophos in technical products by reversed-phase column liquid chromatography.
A simple reversed-phase column liquid chromatographic method for the determination of cis and trans isomers of monocrotophos (MCP) using a C18 column, aqueous acetonitrile as eluent and UV detection at 218 nm was developed. The method was used for quality assurance and to study the relative stabilities of cis and trans isomers in technical products of MCP.
Chromatography, Liquid↗
Separation, identification and determination of sanguinarine in argemone and other adulterated edible oils by reversed-phase high-performance liquid chromatography.
A simple, rapid and reliable reversed-phase high-performance liquid chromatographic method for the separation and determination of sanguinarine in argemone and other edible oils has been developed. The separation has been achieved on a C18 column with CH3OH-CH3CN-tetrahydrofuran-water as mobile phase using diode array detection at 280 nm. The minimum detection limit of sanguinarine in the adulterated edible oils is 5 microg/g.
Alkaloids↗
Gas chromatographic-mass spectrometric separation, identification and determination of C6-C12 cyclic imides in thermally treated epoxy and alkyd resins to locate hot spots inside large electricity generators.
A simple and rapid GC-MS method for separation, identification and quantitative determination of long-chain cyclic imides in the 300 degrees C thermally treated epoxy and alkyd resins has been developed. The method provides a positive means of identifying C6-C12 cyclic imide derivatives by GC-MS and enables the specific area of overheating to be identified, thereby averting catastrophic failures of power generators in service.
Cyclization↗
Conditional transformation of rat embryo fibroblast cells by a cyclin D1-cdk4 fusion gene.
Cyclin D1 gene overexpression is a frequent event in a number of human cancers. These observations have led to the suggestion that cyclin D1 alterations might play a role in the etiology of cancer. This possibility is supported by the finding that transfection of mammalian cells with cyclin D1 can accelerate progression through the G1 phase of the cell cycle. Moreover, cyclin D1 can function as an oncogene by cooperating with activated Ha-ras to transform primary rat embryo fibroblasts (REFs). In addition, cyclin D1 transgenics develop hyperplasia and neoplasia of the thymus and mammary gland. We have constructed a novel fusion gene consisting of full-length human cyclin D1 and cdk4 genes. This fusion gene was expressed in insect cells and the fusion protein was shown to be enzymatically active. The fusion gene was expressed in mammalian cells under the control of tet-repressor. This fusion gene immortalized primary REFs, and cooperated with activated Ha-ras to transform primary REFs, in terms of anchorage-independent growth in vitro and formation of tumors in vivo. Utilizing a tet-regulated gene expression system, we have shown that proliferation of stably transfected primary REFs in vitro and in vivo is dependent on the continued expression of the cyclin D1-cdk4 fusion gene. These cell lines could be useful in the discovery of novel cancer therapeutics to modulate cyclin D1.cdk4 activity.
Animals↗
Casein kinase 2 binds to and phosphorylates BRCA1.
The BRCA1 gene encodes a complex protein that appears to be involved in some aspects of DNA repair, transcription, or cell cycle regulation. The phosphorylation of BRCA1 is enhanced following episodes of DNA damage or during cell cycle progression, indicating that phosphorylation may be an important regulatory mechanism. Through a yeast two hybrid assay, we found that the beta-subunit of casein kinase 2 (CK2) associated with a carboxy-terminal region of BRCA1. This association was much weaker with the same fragment bearing a missense mutation (M1775R) that has been identified in breast tumors. The interaction was also evident in Sf9 cells. Subsequent studies showed that BRCA1 was phosphorylated in vitro by CK2. An analysis by site directed mutagenesis of BRCA1 showed that in vitro phosphorylation by CK2 required a serine at aa1572. These data implicate CK2 as a potential mediator of BRCA1 activity.
Alkaline Phosphatase↗
Purification, characterization, and kinetic mechanism of cyclin D1. CDK4, a major target for cell cycle regulation.
The cyclin D1.CDK4-pRb (retinoblastoma protein) pathway plays a central role in the cell cycle, and its deregulation is correlated with many types of cancers. As a major drug target, we purified dimeric cyclin D1.CDK4 complex to near-homogeneity by a four-step procedure from a recombinant baculovirus-infected insect culture. We optimized the kinase activity and stability and developed a reproducible assay. We examined several catalytic and kinetic properties of the complex and, via steady-state kinetics, derived a kinetic mechanism with a peptide (RbING) and subsequently investigated the mechanistic implications with a physiologically relevant protein (Rb21) as the phosphoacceptor. The complex bound ATP 130-fold tighter when Rb21 instead of RbING was used as the phosphoacceptor. By using staurosporine and ADP as inhibitors, the kinetic mechanism of the complex appeared to be a "single displacement or Bi-Bi" with Mg2+.ATP as the leading substrate and phosphorylated RbING as the last product released. In addition, we purified a cyclin D1-CDK4 fusion protein to homogeneity by a three-step protocol from another recombinant baculovirus culture and observed similar kinetic properties and mechanisms as those from the complex. We attempted to model staurosporine in the ATP-binding site of CDK4 according to our kinetic data. Our biochemical and modeling data provide validation of both the complex and fusion protein as highly active kinases and their usefulness in antiproliferative inhibitor discovery.
Adenosine Triphosphate↗
Malignant rhabdoid tumor of the duodenum.
A polypoid malignant rhabdoid tumor of the duodenum is presented. The pattern of metastatic spread in this 58-year-old man included multiple duodenal and small intestinal transmural tumor implants and a large peribronchial lymph node causing superior vena cava syndrome. Microscopically, the tumor was composed of a diffuse population of rhabdoid cells characterized by homogeneous globular cytoplasmic inclusions that tended to indent or displace eccentric, vesicular nuclei with nucleoli. No glandular features were noted. Immunohistochemical and ultrastructural evaluation revealed that these inclusions contained vimentin, an intermediate filament of the mesenchymal cytoskeleton. Phenotypic features of a rhabdoid tumor have been reported in 10 poorly differentiated malignancies of the gastrointestinal tract. This is the first case report of a malignant rhabdoid tumor of the small intestine. Regardless of the site of the lesion, tumors showing these features are generally associated with a poor prognosis.
Duodenal Neoplasms↗
Construction and characterization of a one-plasmid system for the controlled expression of genes in mammalian cells by tetracycline.
The two-plasmid system of Gossen and Bujard [Gossen and Bujard (1992) Proc. Natl. Acad. Sci. USA 89, 5547-5551] to express mammalian genes in a tetracycline-repressed fashion was combined into a single-plasmid system. Two variants of this single-plasmid system that differ in the multiple cloning site (MCS) region are described. These vectors were used to stably transfect raf kinase domain into the normal rat kidney epithelial cell line (NRKE) to obtain a conditionally transformed cell line. These vectors were also used to stably transfect wild-type and mutant human p53 into the human osteosarcoma cell line, SAOS-2. Tetracycline repressed gene expression in both cell lines; about 12-fold in NRKE and about 80-fold in SAOS-2 cell line.
Animals↗
Production of a novel polyketide through the construction of a hybrid polyketide synthase.
The lactone rings of the polyketides platenolide and tylactone are synthesized by condensation of acetate-, proprionate-, and butyrate-derived precursors. A hybrid tylactone/platenolide synthase was constructed to determine if the choice of substrate is programmed by the polyketide synthase and to ascertain if a substrate different than that normally used in the first step of platenolide synthesis could be incorporated into the final polyketide. In this work, we report the successful incorporation of a propionate in place of the acetate normally used in the first step of platenolide synthesis. This result demonstrates that polyketide synthases choose a particular substrate at defined steps and provides strong evidence that substrate choice is programmed by the acyl transferase domain of a large, multifunctional polyketide synthase.
Acyl Coenzyme A↗
Aflatoxin B1 contamination in groundnut samples collected from different geographical regions of India: a multicentre study.
Under a multicentre study conducted by the Indian Council of Medical Research, 2062 samples of groundnut were collected from rural and urban areas of 11 states representing different geographical regions of the country. These samples were analysed for aflatoxin B1 using the AOAC method. Analytical quality assurance between various participating laboratories was ensured through analysis of check-samples. Twenty-one per cent of groundnut samples collected from 11 states exceeded the permissible Indian regulatory limit of 30 micrograms/kg. No statistically significant difference in percentage of samples contaminated (> 30 micrograms/kg) were observed between pooled rural (22.9%) and urban (19.9%) data. Amongst the 11 states, the minimum and maximum per cent contamination respectively (> 30 micrograms/kg) was observed to be 15.2 in the state of Andhra Pradesh and 28.3 in the state of Haryana. The maximum level of contamination of 833 micrograms/kg was observed in the state of Gujarat. The median level of < 5 micrograms/kg was observed in the states of Gujarat, Haryana, Punjab, Andhra Pradesh and Karnataka. In all other states studied, the median level was found to vary between 10 and 20 micrograms/kg. The 90th percentile values were high in Andhra Pradesh (125 micrograms/kg), Gujarat (111 micrograms/kg) and Haryana (110 micrograms/kg). In the remaining states the 90th percentile value ranged from 60 to 93 micrograms/kg. Analysis of pooled data showed the percentages of samples exceeding the level of contamination of 5 micrograms/kg and 15 micrograms/kg, respectively were 44.9% and 37.4% which therefore, showed a marked increase when compared with the per cent of samples exceeding 30 micrograms/kg in the overall data.
Aflatoxin B1↗
Targets for cancer therapy in the cell cycle pathway.
Progression through the cell cycle is a complex process that is regulated at many levels by several proteins. We are just beginning to understand how these proteins accomplish this regulation. The p16-cyclin D1.cdk4-pRb pathway is one of the most important pathways, which is altered in a majority of cancers of different types. This review focuses on some of the proteins in this pathway that offer new opportunities for drug discovery. Some guidelines to evaluate the relevance of these proteins as targets for cancer therapy and the importance of developing a combination therapy targeting multiple pathways are also discussed.
Animals↗
Accidental acute fatal sodium nitrite poisoning.
An accidental food poisoning outbreak occurred resulting in the death of 14 of the 22 affected persons. Chemical analysis of food materials revealed the presence of sodium nitrite and potassium arsenate. Analysis of urine, gastric contents, liver and kidney, collected at the time of autopsy, confirmed the presence of these chemical substances in high concentrations. Epidemiological data indicated that the food poisoning occurred due to the accidental use of sodium nitrite and potassium arsenate instead of table salt in the preparation of tamarind (Tamarindus indica) soup.
Adolescent↗
Enantiomeric separation and determination of antiparkinsonian drugs by reversed-phase ligand-exchange high-performance liquid chromatography.
A simple and rapid high-performance liquid chromatographic method for the separation and determination of enantiomers of levodopa and carbidopa using a LiChrosper C18 column with aqueous copper-L-phenylalanine as mobile phase was developed. The separation between D- and L-enantiomers of levodopa and carbidopa was fairly good with separation factors of 1.63 and 2.38, respectively. The method was validated using synthetic mixtures and used for quality assurance of commercial formulations.
Carbidopa↗
Nonadenomatous thymic unencapsulated parathyroid tissue as a cause of persistent primary hyperparathyroidism.
Primary hyperparathyroidism may be caused by ectopic intrathymic parathyroid adenomas or hyperplastic parathyroid glands. The association of the ectopic inferior parathyroid glands and the thymus is due to their common embryologic origin from the third pharyngeal pouch. We report a case of primary hyperparathyroidism due to an unusual pathologic parathyroid gland formation: nonadenomatous thymic unencapsulated parathyroid tissue. Two unsuccessful neck exploration revealed only two normal parathyroid glands within the cervical area. Radiologic imaging studies failed to localize an ectopic parathyroid adenoma. Mediastinal exploration and thymectomy showed one small focus of unencapsulated hypercellular parathyroid tissue expanding peripherally along the septa of thymic adipose tissue. The hyperparathyroidism resolved with the surgical procedure.
Adipose Tissue↗
Plasmid cloning vectors for the conjugal transfer of DNA from Escherichia coli to Streptomyces spp.
We have constructed cloning vectors for the conjugal transfer of DNA from Escherichia coli to Streptomyces spp. All vectors contain the 760-bp oriT fragment from the IncP plasmid, RK2. Transfer functions need to be supplied in trans by the E. coli donor strain. We have incorporated into these vectors selectable antibiotic-resistance markers (AmR, ThR, SpR) that function in Streptomyces spp. and other features that should allow for: (i) integration via homologous recombination between cloned DNA and the Streptomyces spp. chromosome, (ii) autonomous replication, or (iii) site-specific integration at the bacteriophage phi C31 attachment site. Shuttle cosmids for constructing genomic libraries and bacteriophage P1 cloning vector capable of accepting approx. 100-kb fragments are also described. A simple mating procedure has been developed for the conjugal transfer of these vectors from E. coli to Streptomyces spp. that involves plating of the donor strain and either germinated spores or mycelial fragments of the recipient strain. We have shown that several of these vectors can be introduced into Streptomyces fradiae, a strain that is notoriously difficult to transform by PEG-mediated protoplast transformation.
Bacteriophages↗
Sequence similarity between macrolide-resistance determinants and ATP-binding transport proteins.
The three macrolide-resistance-encoding genes, tlrC from Streptomyces fradiae, srmB from Streptomyces ambofaciens, and carA from Streptomyces thermotolerans, encode proteins that possess significant sequence similarity to ATP-dependent transport proteins. The N-terminal and C-terminal halves of these proteins are very similar to each other and contain highly conserved regions that resemble ATP-binding domains typically present within the superfamily of ATP-dependent transport proteins. These observations suggest that the mechanism by which these genes confer resistance to macrolides is due to export of the antibiotics, a process that is driven by energy derived from ATP hydrolysis.
Adenosine Triphosphate↗
Cloning a replication function from the streptomycete bacteriophage FP43.
Streptomyces griseofuscus cells carrying a 4.4-kb SphI DNA fragment from bacteriophage FP43 inhibited plaque formation (Pin) by FP43, and the Pin function was localized to a 0.96-kb SacII fragment. The same 4.4-kb SphI fragment was able to replicate freely in several streptomycetes, including S. griseofuscus, and the replication (Rep) function was localized to a 1.2-kb SphI-FspI fragment. Plasmids with FP43 Rep function are unstable and are present at about 20-50 copies per chromosome. Plasmids with FP43 Rep function are compatible with SCP2* plasmids.
Bacteriophages↗