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Biomedical subjects

Madhu Sharma

Publications and source records attributed to Madhu Sharma.

7 recordsLinked to original sources
PubMed2006

Crystal structure of a highly acidic neurotoxin from scorpion Buthus tamulus at 2.2A resolution reveals novel structural features.

The crystal structure of a highly acidic neurotoxin from the scorpion Buthus tamulus has been determined at 2.2A resolution. The amino acid sequence determination shows that the polypeptide chain has 64 amino acid residues. The pI measurement gave a value of 4.3 which is one of the lowest pI values reported so far for a scorpion toxin. As observed in other alpha-toxins, it contains four disulphide bridges, Cys12-Cys63, Cys16-Cys36, Cys22-Cys46, and Cys26-Cys48. The crystal structure reveals the presence of two crystallographically independent molecules in the asymmetric unit. The conformations of two molecules are identical with an r.m.s. value of 0.3A for their C(alpha) tracings. The overall fold of the toxin is very similar to other scorpion alpha-toxins. It is a betaalphabetabeta protein. The beta-sheet involves residues Glu2-Ile6 (strand beta1), Asp32-Trp39 (strand beta3) and Val45-Val55 (strand beta4). The single alpha-helix formed is by residues Asn19-Asp28 (alpha2). The structure shows a trans peptide bond between residues 9 and 10 in the five-membered reverse turn Asp8-Cys12. This suggests that this toxin belongs to classical alpha-toxin subfamily. The surface features of the present toxin are highly characteristic, the first (A-site) has residues, Phe18, Trp38 and Trp39 that protrude outwardly presumably to interact with its receptor. There is another novel face (N-site) of this neurotoxin that contains several negatively charged residues such as, Glu2, Asp3, Asp32, Glu49 and Asp50 which are clustered in a small region of the toxin structure. On yet another face (P-site) in a triangular arrangement, with respect to the above two faces there are several positively charged residues, Arg58, Lys62 and Arg64 that also protrude outwardly for a potentially potent interaction with other molecules. This toxin with three strong features appears to be one of the most toxic molecules reported so far. In this sense, it may be a new subclass of neurotoxins with the largest number of hot spots.

Amino Acid Sequence↗
PubMed2005

Extra thin alginate film: an efficient technique for protoplast culture.

This paper reports an efficient protoplast culture technique, the "extra thin alginate film" technique. The development of this improved method of protoplast culture was an outcome of an assessment of the efficiency and shortcomings of various protoplast culture techniques. The efficiency of this technique was evaluated with two model plant systems, viz., Nicotiana tabacum and Lotus corniculatus, and a comparison was made with the "thin alginate layer" technique, another efficient protoplast culture system. Results indicate that the culture technique with extra thin alginate film is as efficient as the technique with thin alginate layer, with many additional advantages. The present innovation overcomes most of the limitations of protoplast culture techniques described so far and can now be applied to a wide variety of crops to check its general applicability.

Alginates↗
PubMed2005

In vitro propagation of rose--a review.

In vitro propagation of rose has played a very important role in rapid multiplication of cultivars with desirable traits and production of healthy and disease-free plants. During the last several years, different approaches have been made for in vitro propagation of rose. Micropropagation using apical buds or nodal segments and understanding the specific requirements at different stages has been comprehensively covered in literature. New challenges for refinements of protocols for high rate of shoot multiplication and development of cost effective methods has gained importance in the recent past. Importance of liquid static culture for shoot proliferation and root induction for rose is also discussed in the present review. Further, the development of protocol for in vitro plant regeneration which is considered as most important step for successful implementation of various biotechnological techniques used for plant improvement programmes has been adequately addressed in literature. In rose, there are several reports which indicate rapid regeneration and multiplication through organogenesis or somatic embryogenesis. On the whole, the present review gives a consolidated account of in vitro propagation in rose.

Agriculture↗
PubMed2004

Starch deposition and amylase accumulation during somatic embryogenesis in bamboo (Dendrocalamus hamiltonii).

In monocots, the zygotic embryo is protected and nourished by an endosperm. In the present study starch deposition and amylase accumulation was noticed during somatic embryogenesis in stem callus of a bamboo, Dendrocalamus hamiltonii. SEM studies revealed that starch grains were clearly visible in the scutellum during the maturation stage of the somatic embryo. As the somatic embryo developed further, the scutellum got reduced with corresponding increase in amylase. The amylase activity was tested periodically at different developmental stages of embryos. The role of scutellum in somatic embryos for starch deposition and amylase accumulation is discussed.

Amylases↗
PubMed2003

C-reactive proteins as an indicator of sub-clinical infection in cases of premature rupture of membranes.

The present study was conducted on 25 cases of preterm, premature rupture of membranes and 25 patients preterm with intact membranes, between 28-36 weeks of gestation, admitted in the maternity ward of Obstetrics and Gynecology, PGIMS, Rohtak. The sensitivity and specificity of CRP determination was found to be 80% each as an early predictor of subclinical chorioamnionitis. TLC had a low sensitivity of 20% and specificity of 60% in detecting histopathological chorioamnionitis. So CRP estimation is a reliable marker for detection of early choriamnionitis, at the same time, it is quite affordable and reasonably simple.

C-Reactive Protein↗
PubMed2002

Bacteraemia in children.

OBJECTIVES: (i)To know the etiology of bacteraemia in children, (ii) To learn the antibiotic sensitivity pattern of the isolates. METHOD: Over the period of thirteen months 4,368 blood samples (for blood culture) were collected from children in the age group of 0 day-14 years, suspected of having fever and sepsis. Blood samples were collected for blood culture from each case. Organisms were isolated and identified by conventional methods. Antibiotic susceptibility for each isolate was determined by using modified Stokes method. RESULT: 1,001 cases (22.9%) were culture positive. Incidence of bacteraemia in neonates was 521(33.94%). Gram negative organisms were the most predominant isolates (88.8%). Commonest was Klebsiella 471 (47.1%) followed by Salmonella sp. 162 (16.2%) and Pseudomonas 80 (8%) whereas in gram positive, Staphylococcus aureus 76 (7.6%) was the most common. Maximum sensitivity was seen by sulbactum/cefaperazone combination-969 (98.2%) by all isolates. Linezolid 97 (99.0%) was the most sensitive drug for gram positive isolates. CONCLUSION: Gram negative multidrug resistant organisms were the main cause of septicemia in all the age groups. Therefore great caution is required in selection of antibiotic therapy.

Adolescent↗