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Biomedical subjects

Kaushal Kumar

Publications and source records attributed to Kaushal Kumar.

10 recordsLinked to original sources
PubMed2006

Enhancement of luminescence properties in Er3+ doped TeO2-Na2O-PbX (X=O and F) ternary glasses.

An enhancement of luminescence properties in Er3+ doped ternary glasses is observed on the addition of PbO/PbF2. The infrared to visible upconversion emission bands are observed at 410, 525, 550 and 658 nm, due to the 2H9/2-->4I15/2, 2H11/2-->4I15/2, 4S3/2-->4I15/2, 4F9/2-->4I15/2 transitions respectively, on excitation with 797 nm laser line. A detailed study reveals that the 2H9/2-->4I15/2 transition arises due to three step upconversion process while other transitions arise due to two step absorption. On excitation with 532 nm radiation, ultraviolet and violet upconversion bands centered at 380, 404, 410 and 475 nm wavelengths are observed along with one photon luminescence bands at 525, 550, 658 and 843 nm wavelengths. These bands are found due to the 4G11/2-->4I15/2, 2P3/2-->4I13/2, 2H9/2-->4I15/2, 2P3/2-->4I11/2, 2H11/2-->4I15/2, 4S3/2-->4I15/2, 4F9/2-->4I15/2 and 4S3/2-->4I13/2 transitions, respectively. Though incorporation of PbO and PbF2 both enhances fluorescence intensities however, PbF2 content has an important influence on upconversion luminescence emission. The incorporation of PbF2 enhances the red emission (658 nm) intensity by 1.5 times and the violet emission (410 nm) intensity by 2.0 times. A concentration dependence study of fluorescence reveals the rapid increase in the red (4F9/2-->4I15/2) emission intensity relative to the green (4S3/2-->4I15/2) emission with increase in the Er3+ ion concentration. This behaviour has been explained in terms of an energy transfer by relaxation between excited ions.

Erbium↗
PubMed2005

Comparative analysis of chromatin landscape in regulatory regions of human housekeeping and tissue specific genes.

BACKGROUND: Global regulatory mechanisms involving chromatin assembly and remodelling in the promoter regions of genes is implicated in eukaryotic transcription control especially for genes subjected to spatial and temporal regulation. The potential to utilise global regulatory mechanisms for controlling gene expression might depend upon the architecture of the chromatin in and around the gene. In-silico analysis can yield important insights into this aspect, facilitating comparison of two or more classes of genes comprising of a large number of genes within each group. RESULTS: In the present study, we carried out a comparative analysis of chromatin characteristics in terms of the scaffold/matrix attachment regions, nucleosome formation potential and the occurrence of repetitive sequences, in the upstream regulatory regions of housekeeping and tissue specific genes. Our data show that putative scaffold/matrix attachment regions are more abundant and nucleosome formation potential is higher in the 5' regions of tissue specific genes as compared to the housekeeping genes. CONCLUSION: The differences in the chromatin features between the two groups of genes indicate the involvement of chromatin organisation in the control of gene expression. The presence of global regulatory mechanisms mediated through chromatin organisation can decrease the burden of invoking gene specific regulators for maintenance of the active/silenced state of gene expression. This could partially explain the lower number of genes estimated in the human genome.

Cell Nucleus↗
PubMed2004

SPAAN: a software program for prediction of adhesins and adhesin-like proteins using neural networks.

MOTIVATION: The adhesion of microbial pathogens to host cells is mediated by adhesins. Experimental methods used for characterizing adhesins are time-consuming and demand large resources. The availability of specialized software can rapidly aid experimenters in simplifying this problem. We have employed 105 compositional properties and artificial neural networks to develop SPAAN, which predicts the probability of a protein being an adhesin (Pad). RESULTS: SPAAN had optimal sensitivity of 89% and specificity of 100% on a defined test set and could identify 97.4% of known adhesins at high Pad value from a wide range of bacteria. Furthermore, SPAAN facilitated improved annotation of several proteins as adhesins. Novel adhesins were identified in 17 pathogenic organisms causing diseases in humans and plants. In the severe acute respiratory syndrome (SARS) associated human corona virus, the spike glycoprotein and nsps (nsp2, nsp5, nsp6 and nsp7) were identified as having adhesin-like characteristics. These results offer new lead for rapid experimental testing. AVAILABILITY: SPAAN is freely available through ftp://203.195.151.45 CONTACT: ramu@igib.res.in.

Adhesins, Bacterial↗
PubMed2004

Comparative analysis of protein unfoldedness in human housekeeping and non-housekeeping proteins.

Absence of any regular structure is increasingly being observed in structural studies of proteins. These disordered regions or random coils, which have been observed under physiological conditions, are indicators of protein plasticity. The wide variety of interactions possible due to the flexibility of these 'natively disordered' regions confers functional advantage to the protein and the organism in general. This concept is underscored by the increasing proportion of intrinsically unstructured proteins seen with the ascension in the complexity of the organisms. The 'natively unfolded/disordered' state of the protein can be predicted utilizing Uversky's or Dunker's algorithm. We utilized Uversky's prediction scheme and based on the unique position of a protein in the charge-hydrophobicity plot, a derived net score was used to predict the overall disorder of the human housekeeping and non-housekeeping proteins. Substantial numbers of proteins in both the classes were predicted to be unfolded. However, comparative genomic analysis of predicted unfolded Homo sapiens proteins with homologues in Caenorhabditis elegans, Drosophila melanogaster and Mus musculus revealed significant increase in unfoldedness in non-housekeeping proteins in comparison with housekeeping proteins. Our analysis in the evolutionary context suggests addition or substitution of amino acid residues which favour unfoldedness in non-housekeeping proteins compared to housekeeping proteins.

Algorithms↗
PubMed2004

Quick control of bubonic plague outbreak in Uttar Kashi, India.

A localized outbreak of bubonic plague occurred in village Dangud (population 332), district Uttar Kashi, Uttaranchal, India in the second week of October 2004. 8 cases were considered outbreak associated based on their clinical and epidemiological characteristics; 3 (27.3%) of them died within 48 hours of developing illness. All the 3 fatal cases and five surviving cases had enlargement of inguinal lymph nodes. None of them had pneumonia. The age of the cases ranged from 23-70 years and both sexes were affected. No such illness was reported from adjoining villages. The outbreak was fully contained within two weeks of its onset by supervised comprehensive chemoprophylaxis using tetracycline. A total of approximately 1250 persons were given chemoprophylaxis in three villages. There was no clear history of rat fall in the village. No flea was found on rodents or animals. 16 animal serum samples were found to be negative for antibodies against F-1 antigen of Y. pestis. However, Y. pestis was isolated from two rodents (Rattus rattus and Mus musculus) trapped in the village. One case and three animal sera showed borderline sero-positivity against rickettsial infection. The diagnosis of plague was confirmed by detection of four fold rise of antibody titre against F-1 antigen of Yersinia pestis in paired sera of three cases (one of the WHO approved criteria of diagnosis of confirmed plague). This outbreak and the occurrence of earlier outbreaks of plague in Surat (Gujarat) and Beed (Maharashtra) in 1994 and in district Shimla (Himachal Pradesh) in 2002 confirm that plague infection continue to exist in sylvatic foci in many parts of India which is transmitted to humans occasionally. Thus, there is a strong need for the States to monitor the plague activity in known sylvatic foci regularly and have a system of surveillance to facilitate prompt diagnosis and treatment of cases to control the disease. This investigation highlights that with high index of suspicion the disease can be diagnosed early and mounting of supervised comprehensive response can prevent the disease to proceed to pneumonic stage where man to man transmission gets established and outbreak assumes larger dimensions.

Adult↗
PubMed2004

Outbreak investigation of scrub Typhus in Himachal Pradesh (India).

Scrub Typhus outbreak investigation was undertaken during September 2003 in the three worst affected districts Shimla, Solan and Sirmaur in Himachal Pradesh (India). A total of 113 cases and 19 deaths (17.27 percent case fatality rate) were reported from the eight districts, which were reporting cases. Cases were prevalent in all age groups and in both the sexes among the persons frequenting forest for occupational work. 35.7 percent of the patients serum samples showed a titer of > 1: 80 against OX 19 and OXK antigen is suggestive of Scrub Typhus. Entomologically Rattus rattus (39.5 per cent) was the most prevalent species followed by Suncus murinus (22.91 percent), Bandicoota bengalensis (29.16 percent) and Bandicoota indica and Mus musculus (4.16 percent each). Vector species Leptotrombidium deliense and Gahrliepia (schoengastilla) sp. were recorded. The chigger index 23.0 was found to be highest in Vill. Baldian and 5.0 in Vill. Bhatakuffer (Shimla) and 1.0 in Vill. Rebon (Solan), which is above the critical limit of 0.69 per rodents. Other mite species, ixodid ticks, fleas and lice have been recorded.

Adolescent↗
PubMed2002

Feeding pattern of anopheline and culicine mosquitoes in relation to biotopes and seasons in Delhi and environs.

In the studies to know the feeding pattern of various species of mosquitoes, a total of 7461 specimens comprising of Anopheles culicifacies (150), An. stephensi (61), An. subpictus (990), An. annularis (572), Culex quinquefasciatus (5217) and C. vishnui group (471) of mosquitoes were collected from different biotopes of selected localities in Delhi and environs during all the months of the year. The mosquito blood samples were processed by Gel diffusion technique to know the source of blood meal. Results of study revealed that the mosquito species tested in the study were by and large zoophilic and opportunistic feeders. The feeding behaviour was found to be highly influenced by biotopes from where the mosquitoes were collected, village and areas, different climatic seasons, sleeping behaviour of human beings and availability of alternative hosts particularly animal population. Overall anthropophilic index was found to be 24.66% for An. culicifacies, 20.96% for An. stephensi, 16.93% for An. subpictus, 9.96% for An. annularis, 26.33% for C. quinquefasciatus and 36.39% for C. vishnui group of mosquitoes. Feeding behaviour towards other animals viz: bovine, goat, dog, pig and bird for all these mosquito species in different months and biotopes e.g. human dwellings, cattle sheds and mixed dwellings; in different months and seasons of the year have been presented.

Animals↗
PubMed2002

Prevalence of ixodid ticks in Nilgiri district of Tamil Nadu state (India).

The Nilgiri hills provides favourable ecological conditions for the propagation of haematophagous arthropods due to its richness in vegetation and animal fauna. A study was undertaken by the NICD during August to November 1996 on the prevalence of ectoparasitic ticks from different localities of the Nilgiris district of Tamil Nadu state. The ticks were hand picked from various domestic animals of the study area and identified. A total of 1232 adults and immatures of ticks were collected from domestic animals which comprised of the various species in the order of abundance Boophilus microplus, Haemaphysalis bispinosa, Riphicephalus haemaphysaloides and Riphicephalus sanguineus. Studies carried out in the grass lands, meadows and areas adjoining to tea plantations by flagging method revealed mainly immature stages and few adults of Riphicephalus Spp. and Haemaphysalis Spp. The public health importance of the above species have been discussed.

Animals↗