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Biomedical subjects

P Vijayan

Publications and source records attributed to P Vijayan.

At least 19 recordsLinked to original sources
PubMed2004

Antiviral activity of medicinal plants of Nilgiris.

BACKGROUND & OBJECTIVES: Medicinal plants have been traditionally used for different kinds of ailments including infectious diseases. There is an increasing need for substances with antiviral activity since the treatment of viral infections with the available antiviral drugs often leads to the problem of viral resistance. Herpes simplex virus (HSV) causes a variety of life threatening diseases. Since the chemotherapeutic agents available for HSV infections are either low in quality or limited in efficiency, there is a need to search for new and more effective antiviral agents for HSV infections. Therefore in the present study 18 plants with ethnomedical background from different families were screened for antiviral activity against HSV-1. METHODS: Different parts of the plants collected from in and around Ootacamund, Tamil Nadu were extracted with different solvents to obtain crude extracts. These extracts were screened for their cytotoxicity against Vero cell line by assay microculture tetrazolium (MTT) trypan blue dye exclusion, proteins estimation and 3H labeling. Antiviral properties of the plant extracts were determined by cytopathic effect inhibition assay and virus yield reduction assay. RESULTS: Three plant extracts Hypericum mysorense, Hypericum hookerianum and Usnea complanta exhibited significant antiviral activity at a concentration non toxic to the cell line used. The extracts of Melia dubia, Cryptostegia grandiflora and essential oil of Rosmarinus officinalis showed partial activity at higher concentrations. INTERPRETATION & CONCLUSION: Some of the medicinal plants have shown antiviral activity. Further research is needed to elucidate the active constituents of these plants which may be useful in the development of new and effective antiviral agents.

Animals↗
PubMed2003

Antitumor activity of total alkaloid fraction of solanum pseudocapsicum leaves.

The total alkaloid fraction of the methanolic extract of Solanum pseudocapsicum leaves was tested for its in-vivo antitumor activity against Dalton's Lymphoma Ascites model in mice. The total alkaloid fraction at 2.5 and 5.0 mg/kg body weight doses exhibited antitumor activity as revealed by the significant increase in the mean survival time and the percentage increase in life span of tumor bearing mice. The antitumor activity observed may be due to its cytotoxic properties. However the treatment caused a significant decrease in the body weight below the normal indicating the toxicity of the treatment.

Alkaloids↗
PubMed2003

In vitro cytotoxicity and antitumour properties of Hypericum mysorense and Hypericum patulum.

The methanol extracts of the aerial parts of Hypericum mysorense and Hypericum patulum were tested for in vitro cytotoxicity on HEp-2, RD and Vero cell lines and antitumour activity using DLA and HEp-2 cell lines. The cell viability and morphological changes were assessed. Of these extracts, Hypericum patulum (stem) extract showed strong cytotoxicity against all the cell lines used. The CTC50 of the Hypericum patulum (stem) extract was 1.71 microg/mL for HEp-2, 1.53 microg/mL for RD and 2.23 microg/mL for Vero cell lines. The Hypericum patulum (leaves) and Hypericum mysorense (aerial parts) extracts showed moderate cytotoxicity and Hypericum patulum (aerial parts) extract did not show any cytotoxicity up to 1,000 microg/mL concentration. In the clonogenic assay, no colony formation was observed at a concentration of 300 micro g/mL and above for Hypericum mysorense (aerial parts), 400 microg/mL and above for Hypericum patulum (leaves) and 500 microg/mL and above for Hypericum patulum (stem) extracts. In the short term antitumour studies using DLA cells, 50% viability was observed in the concentration range 100-200 microg/mL for Hypericum patulum (leaves and stem) and 200-400 microg/mL for Hypericum mysorense (aerial) extract. In the long term antitumour activity using the HEp-2 cell line, no colony formation was observed over a concentration of 1.6 microg/mL for the Hypericum patulum (stem) extract.

Animals↗
PubMed2000

Discrepancies in Epstein-Barr virus association at presentation and relapse of classical Hodgkin's disease: impact on pathogenesis.

BACKGROUND: Though Epstein-Barr virus (EBV) has been linked to classical Hodgkin's disease (cHD), only a proportion of cHD cases show EBV-association. While there has been evidence to suggest a crucial role for EBV in the early phase of cHD evolution, we are unclear whether continued presence of EBV is essential for the maintenance of the neoplasm. We have addressed this issue by investigating the EBV-association in paired samples of cHD obtained at presentation and relapse. MATERIALS AND METHODS: We have analysed lymph node biopsy samples from 23 cases of cHD at presentation and relapse. In situ hybridization with EBER-1 probe and immunostaining with anti latent membrane protein-1 (LMP-1) antibody was performed on the paraffin sections. PCR for EBNA 3C gene was performed for EBV subtype analysis on the DNA extracted from paraffin sections. RESULTS: EBV-association was documented in both the presentation and relapse samples of 14 cases. One case showed loss of EBV-association at relapse. PCR analysable DNA was obtained from both presentation and relapse samples in four of the EBV-associated cases. The EBNA 3C amplimer corresponded to type A strain of EBV in all the samples. CONCLUSION: Loss of EBV-association between presentation and relapse seen in one case implies a hit and run mechanism in EBV-induced lymphomagenesis. Though EBV may be essential early in the evolution of cHD, it may not be required for maintenance of the neoplastic clone. Our study also brings out a speculation that a proportion of EBV-negative cHD could represent loss of EBV in the tumour prior to clinical presentation. Alternatively, an unidentified lymphotropic virus other than EBV might play a pathogenetic role in EBV-negative cHD.

Burkitt Lymphoma↗
PubMed1999

Studies on the antibacterial potential of Cryptostegia grandiflora R. Br. (Asclepiadaceae) extract.

Different extracts of Cryptostegia grandiflora (Roxb) Rbr. leaves were investigated for their antibacterial potential against Pseudomonus cepacia NCIM-2106, Bacillus megatorium NCIM-2087, Staphylococcus aureus NCIM-2492, Escherichia coli NCIM-2345, Bacillus subtilis NCIM-2349 and Bacillus coagulans NCIM 2323. Almost all the extracts produced significant antibacterial activity against all the microorganisms being tested and the effect so produced was comparable to the standard antibiotic, tetracycline hydrochloride. The petroleum ether (60 degrees-80 degrees C) extract showed maximum efficacy.

Africa↗
PubMed1998

A role for jasmonate in pathogen defense of Arabidopsis.

To investigate the role of jasmonate in the defense of plants against fungal pathogens, we have studied a mutant of Arabidopsis, fad3-2 fad7-2 fad8, that cannot accumulate jasmonate. Mutant plants were extremely susceptible to root rot caused by the fungal root pathogen Pythium mastophorum (Drechs.), even though neighboring wild-type plants were largely unaffected by this fungus. Application of exogenous methyl jasmonate substantially protected mutant plants, reducing the incidence of disease to a level close to that of wild-type controls. A similar treatment with methyl jasmonate did not protect the jasmonate-insensitive mutant coi1 from infection, showing that protective action of applied jasmonate against P. mastophorum was mediated by the induction of plant defense mechanisms rather than by a direct antifungal action. Transcripts of three jasmonate-responsive defense genes are induced by Pythium challenge in the wild-type but not in the jasmonate-deficient mutant. Pythium species are ubiquitous in soil and root habitats world-wide, but most (including P. mastophorum) are considered to be minor pathogens. Our results indicate that jasmonate is essential for plant defense against Pythium and, because of the high exposure of plant roots to Pythium inoculum in soil, may well be fundamental to survival of plants in nature. Our results further indicate that the fad3-2 fad7-2 fad8 mutant is an appropriate genetic model for studying the role of this important signaling molecule in pathogen defense.

Journal Article↗
PubMed1998

Chloroplast development at low temperatures requires a homolog of DIM1, a yeast gene encoding the 18S rRNA dimethylase.

Poikilothermic organisms require mechanisms that allow survival at chilling temperatures (2 to 15 degreesC). We have isolated chilling-sensitive mutants of Arabidopsis, a plant that is very chilling resistant, and are characterizing them to understand the genes involved in chilling resistance. The T-DNA-tagged mutant paleface1 (pfc1) grows normally at 22 degrees C but at 5 degrees C exhibits a pattern of chilling-induced chlorosis consistent with a disruption of chloroplast development. Genomic DNA flanking the T-DNA was cloned and used to isolate wild-type genomic and cDNA clones. The PFC1 transcript is present at a low level in wild-type plants and was not detected in pfc1 plants. Wild-type Arabidopsis expressing antisense constructs of PFC1 grew normally at 22 degrees C but showed chilling-induced chlorosis, confirming that the gene is essential for low-temperature development of chloroplasts. The deduced amino acid sequence of PFC1 has identity with rRNA methylases found in bacteria and yeast that modify specific adenosines of pre-rRNA transcripts. The pfc1 mutant does not have these modifications in the small subunit rRNA of the plastid.

Acclimatization↗
PubMed1993

Developmental and tissue-specific expression of a tomato anionic peroxidase (tap1) gene by a minimal promoter, with wound and pathogen induction by an additional 5'-flanking region.

The tomato anionic peroxidase genes (tap1 and tap2) are induced by wounding and pathogen attack. The 5'-flanking region of tap1 confers wound- and pathogen-inducible beta-glucuronidase (GUS) expression in tobacco plants transformed with a tap1/GUS chimeric fusion gene construct. A series of nested 5' promoter deletions in the tap1/GUS fusion gene construct was created, and introduced into tobacco protoplasts via polyethylene glycol-mediated DNA transfer. A -202 construct (where the transcriptional start site is denoted +1) and larger tap1 promoter constructs showed constitutive GUS expression. A 2-fold increase in GUS expression over the high constitutive levels was observed with -358 bp and larger tap1 constructs when protoplasts were incubated with elicitor preparations from Verticillium albo-atrum. In tobacco plants transformed with the tap1 promoter deletion/GUS fusion gene constructs, wounding caused induction of GUS expression by 20 h that increased 6- to 18-fold by 72 h. The region between -202 and -358 of the tap1 promoter conferred wound responsiveness. GUS was also found to be expressed in the epidermis and trichomes in the aerial parts of transgenic plants. High-level GUS expression was observed in the nodal region of stems that was associated with the leaf traces. GUS that was absent in very young flower buds was found in the subsequent developmental stages in the pistils, ovaries and anthers. The developmentally regulated tissue-specific expression of GUS was found with all constructs containing the -202 and larger promoters whereas wound and pathogen induction required -358 or larger promoter. These results suggest that the tap1 gene, which was heretofore thought to be expressed only upon wounding or pathogen attack, plays a role in normal developmental processes of the plant and this gene acquired additional 5'-flanking promoter for the purpose of responding to wounding and fungal attack.

Base Sequence↗
PubMed1992

Inhibition of the cation-induced reversible changes in excitation energy distribution in thylakoids of BASF 13.338-grown plants.

Measurements of relative quantum yields of Photosystem II and Photosystem I partial reactions and room-temperature chlorophyll a fluorescence of thylakoids in high- and low-salt media showed that the cation-induced changes in the excitation energy distribution were inhibited in the thylakoids isolated from pea plants grown in the presence of sublethal concentration of the pyridazinone herbicide BASF 13.338. Simultaneous measurement of Photosystem II and Photosystem I fluorescence emission kinetics at 77 K showed that the ability of cations to regulate excitation energy spillover from Photosystem II to Photosystem I was inhibited in thylakoids of the BASF-grown plants. Cation regulation of the absorption cross-section of the photosystems was not affected. Electron microscope data revealed that the proportion of stroma membranes relative to grana membranes was markedly less in the thylakoids of the BASF-grown plants. Furthermore, when the thylakoids were resuspended in low-salt medium, no unstacking of the grana was detected. The observed inhibition of cation-induced spillover change was presumably due to loss of ability of these photosynthetic membranes to undergo unstacking in low-salt medium.

Cations↗
PubMed1991

Management of fracture of the penis in Qatar.

We present 21 patients with fracture of the penis treated between July 1982 and July 1990. Eighteen patients were treated surgically, with good functional and morphological recovery; 3 refused surgery, 1 of whom had penile deformity and pain on erection. The literature is reviewed with respect to the necessity of different diagnostic and therapeutic options.

Adult↗
PubMed1991

Percutaneous nephrolithotomy through an intercostal approach.

During a 5-year period percutaneous nephrolithotripsy through an intercostal space was performed in 56 of 231 procedures. Minimal thoracic complications were seen in 3 of 53 patients with 11th intercostal space tracts into a lower, middle, or upper pole calyx. A working sheath and a pyelostomy drainage catheter were used in all these cases. Hydro- and pneumothorax requiring treatment occurred in 2 of 3 patients with a 10th intercostal space approach into an upper pole calyx combined with improper use of the working sheath and/or the pyelostomy catheter. Review of the literature also indicates that an intercostal approach appears safe when performed via the 11th intercostal space into a lower or middle pole calyx. Thoracic complications occurred when punctures were made towards an upper pole calyx or above the 11th rib. The complications may be limited by identifying the posterior inferior lung border by fluoroscopy during puncture, and performing it under general anesthesia with controlled breath-holding. The use of a working sheath to seal the pleural opening during the procedure and an efficient pyelostomy drainage catheter to allow free drainage of urine and to tamponade the tract postoperatively are also recommended.

Adult↗
PubMed1990

Primary double pigtail stenting as a treatment of upper urinary tract leaks.

During a 5-year period 21 consecutive patients with iatrogenic or traumatic upper urinary tract leaks (nonmalignant) underwent treatment 5 to 28 days later with an indwelling double pigtail stent via an antegrade or retrograde approach. Six patients underwent initial nephrostomy drainage for relief of obstruction causing decreased renal function and/or septicemia. Stent placement was successful in 20 patients and complete healing occurred within 2 to 7 weeks in all 20. At followup 2 to 32 months later (median 3 months) no stricture formation or deterioration of kidney function was noted. There were no major complications and 85% of the patients were able to leave the hospital without any form of external drainage within 1 week after stent placement.

Adult↗
PubMed1989

Linitis plastica-like carcinoma of the urinary bladder.

Two cases of signet-ring cell adenocarcinoma of the urinary bladder with a linitis plastica pattern of infiltration were studied. Mucin histochemistry indicated the presence of neutral and acid mucopolysaccharides and absence of sulphomucin. Immunocytochemistry of the tumour cells was positive for keratin and carcinoembryonic antigen, but negative for prostatic specific antigen and vimentin. The relevance of these observations to the differentiation and histogenesis of these tumours is discussed.

Adenocarcinoma, Mucinous↗
PubMed1987

Balloon dilatation of bilharzial ureteric strictures.

Balloon dilatation was performed in nine patients with bilharzial ureteric strictures. In six patients a percutaneous, antegrade approach was used and in three a balloon catheter was introduced into the ureter via a cystoscope. In another four patients, negotiation of the strictured area with a guide wire failed. In all dilated patients, symptomatic and urographic relief of the obstruction was obtained during follow-up periods of 3 to 38 months (mean 19). One patient was re-dilated after 24 months and has remained symptom-free for a further 18 months. Balloon dilatation seems to be a promising method of treating this condition.

Adult↗