Depurination of ribosomal RNA and inhibition of viral RNA translation by an antiviral protein of Celosia cristata.

An antiviral protein (25 kD) isolated from leaves of Celosia cristata (CCP 25) was tested for depurination study on ribosomal RNA from yeast. Ribosomal RNA yielded 360 nucleotide base fragment after treatment with CCP 25 indicating that CCP 25 was a ribosome inactivating protein. CCP 25 also inhibited translation of brome mosaic virus (BMV) and pokeweed mosaic virus (PMV) RNAs in rabbit reticulocyte translation system. The radioactive assay showed that incorporation of [35S]-methionine was less in translation proteins of BMV nucleic acid when CCP 25 was added to translation system. This indicated that antiviral protein from Celosia cristata not only depurinated ribosomal RNA but also inhibited translation of viral RNA in vitro.

Purification and properties of antiviral proteins from the leaves of Bougainvillea xbuttiana.

A non-phytotoxic, resistance inducing, proteinaceous antiviral principle was purified by ammonium sulphate fractionation, ion exchange chromatography and gel filtration from the leaves of Bougainvillea xbuttiana. It imparted resistance against tobacco mosaic virus (TMV) and sunnhemp rosette virus (SRV) in their respective test hosts viz. Nicotiana glutinosa, N. tabacum var. Samsun NN, and Cyamopsis tetragonoloba, respectively. The purified principle eluted as a single peak upon gel filtration, but exhibited two polypeptides on SDS-PAGE with Mr 28,000 and 24,000. The two polypeptides were found to be highly basic, rich in lysine with pI around 10.0 and 10.5, respectively. Since this principle effected local lesion inhibition in both treated and untreated top leaves of test host, it might be acting in the initial stages of virus infection as a systemic inducer.

Purification and characterization of a 29 kDa poly(A)-binding protein from chickpea (Cicer arietinum) epicotyl.

A poly(A)-binding protein (PABP) with mol wt 29,000 has been purified from chickpea (Cicer arietinum) epicotyl by ammonium sulfate fractionation and Cibacron blue F3-GA chromatography, making a complex with poly(A) and elution of PABP-poly(A) complex at 45 degrees C from oligo d(T)-cellulose. The elution pattern and binding properties show that the purified protein is different from the PABP (mol. wt 72,000) reported earlier from our laboratory.

A systemic resistance inducing antiviral protein with N-glycosidase activity from Bougainvillea xbuttiana leaves.

An antiviral protein from Bougainvillea xbuttiana leaves induced systemic resistance in host plants N. glutinosa and Cyamopsis tetragonoloba against TMV and SRV, respectively which was reversed by actinomycin D, when applied immediately or shortly after antiviral protein treatment. When the inhibitor was applied to the host plant leaves post inoculation, it was effective if applied upto 4 h after virus infection. It also delayed the expression of symptoms in systemic hosts of TMV. The inhibitor showed characteristic N-glycosidase activity on 25S rRNA of tobacco ribosomes, suggesting that it could also be interfering with virus multiplication through ribosome-inactivation process.

Auxin regulated poly(A)polymerase activity in Cicer arietinum epicotyls.

There was a linear increase in poly (A+) polymerase activity in the C. arietinum epicotyls during germination. Six-day-old auxin treated seedlings showed about 3-4 fold stimulation in enzyme activity, accompanied with 3- fold rise in the relative abundance of poly (A+) RNA levels. Actinomycin D, cycloheximide, cordycepin and amino acid analogues caused dramatic decline in poly (A+) polymerase as well as poly (A+) RNA levels. It seems that auxin induced a de novo synthesis of this enzyme.

Purification and characterization of a poly(A)-binding protein from chickpea (Cicer arietinum) epicotyl.

A poly(A)-binding protein (PABP) with mol wt 72,000 has been purified from chickpea (Cicer arietinum) epicotyls by ammonium sulfate fractionation, Cibacron blue F3-GA and poly(A) agarose chromatography. The binding properties and the specificity of binding show that the purified protein is an analogue of PABPs in other eukaryotes. This PABP is highly susceptible to proteolysis and upon degradation forms a polypeptide fragment of mol wt 21,000 which has an independent poly(A) binding activity.

Spectrum of antibiogram against pathogens related to respiratory tract infections with a special reference to ceftibuten: a multicentric study.

In a multicentric study at several leading hospitals of this country, microbiological assessment was carried out in 500 specimens from patients suffering from respiratory tract infections (RTIs; both upper and lower) for a period of 6 months from January, 1999 to June, 1999. The antibiotic sensitivity study was done in 201 isolates from 500 different specimens of throat swab, postpharyngeal swab, sinusitis drainage fluid, sputum, broncho-alveolar lavage (BL), etc. Ceftibuten, an orally active third generation cephalosporin showed encouraging results when compared with seven other selected antibiotics used for RTI. The majority of the patients with acute or chronic RTIs showed an excellent in vitro response to ceftibuten in the analysis of the isolates. Seventy to ninety per cent of the isolated respiratory pathogens were found to be sensitive to ceftibuten in vitro; which offers a promising alternative to other antibiotics included in this study.

Evaluation of efficacy of Dettol-H in hospital use.

A study was conducted at Safdarjang Hospital, New Delhi, to elucidate the bactericidal effect of a new disinfectant having benzalkonium chloride (40%) + disodium edetate (1.5%) and commercially available as Dettol-H, in comparison with that of a disinfectant already in-use in this hospital and having chlorhexidine gluconate (7.5%) + cetrimide (15%) + isopropyl alcohol (commercially available as Alpilon). The modified Capacity test of Kelsey-Sykes and In-use test of Kelsey-Maurer were carried out using control strains and random gram positive and gram negative bacterial isolates from clinical specimens. The two disinfectant solutions were analysed at three dilutions viz. weak, recommended and strong. From the study it could be inferred that both Dettol-H and Alpilon were equally effective in recommended and strong dilutions against the organisms tested. Weak dilutions were not effective in both and hence Dettol-H and Alpilon are effective only if used in prescribed concentrations.

Resistance to quinolones in pathogens causing urinary tract infections.

157 bacterial isolates from cases with urinary tract infections (UTI) were studied for their susceptibility to some of the available quinolones as compared to other commonly used antimicrobial agents in UTI. Resistance to nalidixic acid was observed in 62.4% of isolates whereas for pefloxacin, norfloxacin, ciprofloxacin and lomifloxacin it was 54.7%, 52.5%, 51.5% and 50.3% respectively. Aminoglycosides and third generation cephalosporins showed resistance in fewer isolates. Gentamicin resistance was observed in 21% and corresponding figure for amikacin, cefotaxime and ceftriaxone was 7%, 8.9% and 12.1% respectively. Nitrofurantoin showed resistance in 36.3% of isolates and 48% isolates were resistant to cephalexin. The minimum inhibitory concentration (MIC) of quinolones was more than 64 mcg/ml which is > 8 times in resistant strains as compared to sensitive isolates.

Blackgram mottle virus RNA and its in vitro translation.

In vitro translation of blackgram mottle virus RNA in rabbit reticulocyte lysate resulted in synthesis of five major virus specific polypeptides with mol wt 90,000(p90), 82,000(p82), 42,000(p42), 39,000(p39) and 32,000(p32), respectively. The polypeptide p39 was identified as coat protein based on its electrophoretic mobility and immunoprecipitation with BMoV-antiserum.