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R Sardana

Publications and source records attributed to R Sardana.

9 recordsLinked to original sources
PubMed2001

Sorting of glycoprotein B from human cytomegalovirus to protein storage vesicles in seeds of transgenic tobacco.

As part of ongoing studies into the use of plant expression systems for making human therapeutic proteins, we have successfully expressed the major glycoprotein, gB, of human cytomegalovirus (HCMV) in transgenic tobacco plants. Viral glycoprotein was detectable in the protein extracts of mature tobacco seeds using neutralizing and non-neutralizing monoclonal antibodies specific for gB. Although several mammalian proteins have been expressed in tobacco, localization of these proteins in transgenic tobacco tissue has not been extensively examined. The objective of this study was to identify the site(s) of recombinant gB deposition in mature tobacco seeds. Using immunogold labelling and electron microscopy, we found specific labelling for gB in the endosperm of transgenic seeds, with gB localized almost exclusively in protein storage vesicles (PSV). This occurred in seeds that were freshly harvested and in seeds that had been stored for several months. These data indicate that gB behaves like a plant storage protein when expressed in tobacco seeds, and provide further support for the suitability of plants for producing recombinant proteins of potential clinical relevance.

Humans↗
PubMed1999

Development of biopharmaceuticals in plant expression systems: cloning, expression and immunological reactivity of human cytomegalovirus glycoprotein B (UL55) in seeds of transgenic tobacco.

Plant seeds offer unique opportunities for the production and delivery of oral subunit vaccines. We have used the immunodominant glycoprotein B complex of human cytomegalovirus (HCMV), introduced into tobacco plants, as a model system for studying the merit of this promising approach. Given the advantages of expressing proteins in seeds, a novel expression vector was developed incorporating regulatory sequences of glutelin, the major rice seed storage protein, to direct synthesis of recombinant glycoprotein B. Analysis of genomic DNA of 28 selected tobacco transformants by PCR amplification showed that 71% harboured the gB cDNA, a finding further documented by Southern blotting. Specific immunoassays of protein extracts from seeds of positive plants showed that all were producing antigenic glycoprotein B at levels ranging from 70-146 ng/mg extracted protein. In addition, similarity with native glycoprotein B produced in HCMV-infected cells was also demonstrated by inhibition of immunofluorescence on HCMV-infected human fibroblasts. These data are the first to report the expression of an immunodominant antigen of HCMV in plant tissues, indicating the fidelity with which this very large heterologous viral glycoprotein can be synthesized in this model system.

Animals↗
PubMed1998

Agrobacterium-transformed rice plants expressing synthetic cryIA(b) and cryIA(c) genes are highly toxic to striped stem borer and yellow stem borer.

Over 2,600 transgenic rice plants in nine strains were regenerated from >500 independently selected hygromycin-resistant calli after Agrobacterium-mediated transformation. The plants were transformed with fully modified (plant codon optimized) versions of two synthetic cryIA(b) and cryIA(c) coding sequences from Bacillus thuringiensis as well as the hph and gus genes, coding for hygromycin phosphotransferase and beta-glucuronidase, respectively. These sequences were placed under control of the maize ubiquitin promoter, the CaMV35S promoter, and the Brassica Bp10 gene promoter to achieve high and tissue-specific expression of the lepidopteran-specific delta-endotoxins. The integration, expression, and inheritance of these genes were demonstrated in R0 and R1 generations by Southern, Northern, and Western analyses and by other techniques. Accumulation of high levels (up to 3% of soluble proteins) of CryIA(b) and CryIA(c) proteins was detected in R0 plants. Bioassays with R1 transgenic plants indicated that the transgenic plants were highly toxic to two major rice insect pests, striped stem borer (Chilo suppressalis) and yellow stem borer (Scirpophaga incertulas), with mortalities of 97-100% within 5 days after infestation, thus offering a potential for effective insect resistance in transgenic rice plants.

Bacillus thuringiensis↗
PubMed1993

Correlation between the size of the intergenic regulatory region, the status of cytosine methylation of rRNA genes and nucleolar expression in wheat.

A large number of wheat rRNA genes are methylated at all the CCGG sites that are present in the intergenic regions. A smaller number of rRNA genes are not methylated at one or more CCGG sites. A subset of genes was found unmethylated at a specific CCGG site just downstream of the array of 135 bp A repeats in the intergenic region. In all the genotypes studied, the rDNA loci with larger intergenic regions between their genes also possess a greater number of rRNA genes that are unmethylated at one or more CCGG sites in the intergenic regions than do the loci with shorter intergenic regions. In four genotypes (for which data were available), rDNA loci with longer intergenic regions had larger secondary constrictions on metaphase chromosomes, a measure of relative locus activity, than the loci with shorter intergenic regions. The results have been integrated into a model for the control of rDNA expression based on correlations between cytosine methylation patterns and the number of upstream 135 bp repeats in intergenic regions. According to this model the 135 bp repeats play a part in the control of gene activity by binding a protein(s) that is in limiting supply, thereby predisposing the neighbouring gene to become active preferentially.

Cell Nucleolus↗
PubMed1992

A Brassica napus gene family which shows sequence similarity to ascorbate oxidase is expressed in developing pollen. Molecular characterization and analysis of promoter activity in transgenic tobacco plants.

The genomic clone named Bp10 contains a member of a small pollen-specific gene family of B. napus. The expression of the Bp10 gene family is maximal in early binucleate microspores and declines considerably in mature trinucleate pollen. Homologues of the Bp10 genes are expressed in the pollen of other plant species. The pollen-specific expression of the gene contained in the genomic clone was confirmed in tobacco plants transformed with a chimeric Bp10 promoter/GUS construct. A promoter fragment of 396 bp is sufficient to direct a strong and correct spatial and temporal expression in transgenic plants. The Bp10 gene family codes for proteins of 62 kDa showing approximately 30% sequence identify to cucumber and pumpkin ascorbate oxidases (AAOs). However, the AAO active centres are not conserved in the Bp10 products, suggesting an evolutionary relationship but a different enzymatic activity for these proteins. Expression of a recombinant Bp10 protein in E. coli inhibits bacterial growth on minimal medium, suggesting the production of an enzymatically active polypeptide in bacteria. No AAO activity could be correlated with the expression of the recombinant protein. Moreover, substances affecting AAO activity do not appear to influence the inhibitory activity of the protein produced in bacteria. However, as indicated by the rescue of bacterial growth in the presence of sodium bicarbonate or gaseous CO2, the Bp10 protein activity could be modulated by CO2 levels.

Amino Acid Sequence↗
PubMedDate not supplied

Nutritional management of osteoporosis. To slow the advancement of osteoporosis, nurses must encourage their clients to increase their intake of calcium. For geriatric nurses, this may be a challenge.

In conclusion, no current effective therapy is available for the restoration of bone mass once osteoporosis has developed. Primary prevention is the best way to fight this problem. However, goals for the management of osteoporosis are (1) to maintain skeletal mass and integrity, (2) to slow bone resorption, and (3) to treat the symptomatic problem and its sequelae. Having a well-balanced diet containing adequate amounts of calcium, use of calcium supplements when necessary, reducing risk factors in life-style, and use of estrogen are therapeutic measures to reduce bone loss. Clients are also encouraged to exercise by walking or swimming and remain as active as possible. It is important to avoid strain on the spine, as occurs in lifting or bending, to prevent compression fractures on the vertebrae. For treating the symptoms of osteoporosis and its sequelae, it is necessary to relieve pain (by the use of analgesics), provide comfortable light mechanical support for the spine, if needed, arrange assistance in activities of daily living, coordinate a rehabilitation program, and provide emotional support and reassurance to the patient and family. This may be an area largely neglected in practice. Gerontologic nurses may be the first to take the time to thoroughly discuss osteoporosis with their elderly clients and help them to develop a comprehensive program. If through their efforts some falls and fractures can be prevented, this is nursing at its best.

Aged↗
PubMedDate not supplied

Catheter ablation of left free wall accessory pathway in a patient with inferior vena cava interruption.

Access to the right side of the heart for diagnostic and interventional procedures is usually obtained via the femoral vein and inferior vena cava. Anatomic variations or obstruction of the inferior vena cava can make this access difficult. In such cases, alternative routes to the right side of the heart such as the azygos vein and the superior vena cava can be used.

Azygos Vein↗