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Biomedical subjects

P Roy

Publications and source records attributed to P Roy.

At least 73 records · Page 4Linked to original sources
PubMed2000

A thyrotropin-like molecule from the pituitary of an Indian freshwater murrel: comparison of its biological activity with other thyrotropins.

Murrel pituitary thyrotropin-like molecule (mTSH) was purified to homogeneity with the help of a convenient and sensitive in vitro assay system where addition of this material to the thyroid follicle incubation stimulated thyroxine (T(4)) secretion into the medium. Pituitary extract of a freshwater murrel, Channa punctatus, was solvent extracted to obtain glycoprotein enriched fraction. This was subjected to Sephadex G-100 gel filtration and eluate of void volume (peak I) showed strong TSH activity (as reflected from T(4) secretion) which was further purified by using concanavalin A-Sepharose, FPLC Mono Q and immunoaffinity chromatography. Purified mTSH gave a single band in PAGE, and SDS PAGE revealed two dissimilar subunits, alpha and beta. Addition of increasing concentrations of mTSH, Indian carp TSH (cTSH) and bovine TSH (bTSH) to in vitro murrel thyroid follicle incubations caused a linear increase in thyroxine (T(4)) release into the medium, effect was highest with mTSH and lowest with bTSH. However, in in vivo experiments, injections of increasing doses of mTSH to murrel elevated plasma T(4) level in a linear manner while bTSH gave a biphasic response. Addition of mTSH and bTSH to rat or goat thyroid epithelial cell incubations equally stimulated T(4) release into the medium, while cTSH had significantly less effect. Binding affinity (K(a)) and receptor occupancy (B(max)) of mTSH to murrel thyroid follicular membrane preparation was considerably higher in comparison to cTSH or bTSH whereas both mTSH and bTSH had nearly similar K(a) and B(max) with rat thyroid epithelial cell membrane preparation. Findings indicate that mTSH is a more potent TSH as compared to carp and bovine TSH in murrel and has equipotent biological activity as bTSH on rat and goat thyroid.

Animals↗
PubMed2000

Long-term survival in Hodgkin's disease patients. A comparison of relative survival in patients in trials and those recorded in population-based cancer registries.

The prognosis of Hodgkins disease (HD) has improved during the last 30 years. This study was planned to analyse long-term survival of LID patients and to compare survival rates estimated from clinical trials and population-based data. Individual data were analysed on 2,755 adult HD patients entering randomised clinical trials of the British National Lymphoma Investigation BN LI) between 1970 and 1987, and 5,064 patients with HD incident 1978-1984 recorded in the UK population-based cancer registries participating in the EUROCARE study. Relative survival of Hodgkins disease patients allowing for mortality expected from general population rates was analysed by a proportional hazards regression model including covariates. Although relative mortality decreased with longer follow-up, it was still significantly positive at 9-10 years after diagnosis in both the clinical trials and the population-based data sets. Relative mortality was worse for late stage than for early stage patients even at 10-15 years after first treatment (BNLI data). Whereas 10-year relative survival was identical in trials and population-based patients at ages under 45 years (> 69%), it was much higher in BNLI older patients than in the population-based patients. In the older age group (65-74 years) the BNLI patients had 39% relative survival whilst for the population-based patients it was only 27%, Generalisation of clinical trials results to the general population must be done with caution, especially for older patients.

Adolescent↗
PubMed2000

Antigenetically unusual Newcastle disease virus from racing pigeons in India.

Newcastle disease virus isolated from an outbreak in racing pigeons in India was found to be velogenic, based on the mean time to death in 10-day-old embryonated hen's eggs, the intravenous pathogenicity index in 6-week-old chickens and the pathogenesis in chickens and pigeons. The virus induced disease in chickens without prior adaptation in chickens. The virus was antigenically unusual since it could not be grouped with the available panel of monoclonal antibodies at the World Reference Laboratory for Newcastle disease, UK. However, commercially available lentogenic and mesogenic vaccines provided 100% protection to chickens against this antigenically unusual NDV.

Animals↗
PubMed2000

Characterization of Newcastle disease viruses isolated from chickens and ducks in Tamilnadu, India.

During 1993, outbreaks of Newcastle disease occurred on many farms in Tamilnadu, India. Six Newcastle disease virus (NDV) isolates were obtained from the chickens on five different farms and from the birds on one duck farm during outbreaks of the disease. All the isolates were characterized as velogenic, based on the mean death time, intravenous pathogenicity index, intracerebral pathogenicity index (ICPI), stability of haemagglutinin at 56 degrees C, agglutination of equine erythrocytes, haemagglutination elution pattern and adsorption of haemagglutinin by chick brain cells. The isolate obtained from ducks resembled a group D strain, based on its ICPI and its reaction with a panel of monoclonal antibodies. The other five NDV isolates obtained from chickens were placed in groups B(1), C1(2) and D(2) on the basis of their binding patterns with the panel of monoclonal antibodies. In challenge experiments, it was found that LaSota vaccine provided 100% protection against each of these field isolates and against a local NDV strain obtained from the Institute of Veterinary Preventive Medicine, Tamilnadu, India, while unvaccinated chickens succumbed to challenge. The possible origin of epizootic viruses causing outbreaks in vaccinated flocks is discussed.

Animals↗
PubMed2000

Methodological questions in sentinel lymph node analysis in breast cancer patients.

BACKGROUND: The sentinel lymph node (SLN) procedure has been proposed to women with breast cancer with clinically negative axillary lymph nodes, in order to avoid conventional axillary lymph node dissection and its associated side-effects. Methodological aspects of the validation of the SLN procedure are questioned here. MATERIALS AND METHODS: The results of relevant published studies are reviewed, with emphasis on pathological techniques. The ability of the SLN procedure to diagnose lymph node metastases, the extent to which axillary lymph node dissection contributes to treatment, apart from identification of the stage, and the effect of a modified staging procedure on treatment strategies are analyzed. RESULTS AND CONCLUSION: Both the sensitivity and the negative predictive value of the SLN procedure are overestimated if the probability of missing lymph node metastases is not taken into account, even when a complete axillary dissection is performed as a control. The SLN strategy and its effects on staging and treatment cannot be evaluated by comparison with conventional axillary lymph node dissection in a one-arm study but require carefully designed randomized trials.

Algorithms↗
PubMed2000

A soxA gene, encoding a diheme cytochrome c, and a sox locus, essential for sulfur oxidation in a new sulfur lithotrophic bacterium.

A mobilizable suicide vector, pSUP5011, was used to introduce Tn5-mob in a new facultative sulfur lithotrophic bacterium, KCT001, to generate mutants defective in sulfur oxidation (Sox(-)). The Sox(-) mutants were unable to oxidize thiosulfate while grown mixotrophically in the presence of thiosulfate and succinate. The mutants were also impaired in oxidizing other reduced sulfur compounds and elemental sulfur as evident from the study of substrate oxidation by the whole cells. Sulfite oxidase activity was significantly diminished in the cell extracts of all the mutants. A soxA gene was identified from the transposon-adjacent genomic DNA of a Sox(-) mutant strain. The sequence analysis revealed that the soxA open reading frame (ORF) is preceded by a potential ribosome binding site and promoter region with -10- and -35-like sequences. The deduced nucleotide sequence of the soxA gene was predicted to code for a protein of 286 amino acids. It had a signal peptide of 26 N-terminal amino acids. The amino acid sequence showed similarity with a putative gene product of Aquifex aeolicus, soluble cytochrome c(551) of Chlorobium limicola, and the available partial SoxA sequence of Paracoccus denitrificans. The soxA-encoded product seems to be a diheme cytochrome c for KCT001 and A. aeolicus, but the amino acid sequence of C. limicola cytochrome c(551) revealed a single heme-binding region. Another transposon insertion mutation was mapped within the soxA ORF. Four other independent transposon insertion mutations were mapped in the 4.4-kb soxA contiguous genomic DNA region. The results thus suggest that a sox locus of KCT001, essential for sulfur oxidation, was affected by all these six independent insertion mutations.

Amino Acid Sequence↗
PubMed2000

Functional dissection of the major structural protein of bluetongue virus: identification of key residues within VP7 essential for capsid assembly.

A lattice of VP7 trimers forms the surface of the icosahedral bluetongue virus (BTV) core. To investigate the role of VP7 oligomerization in core assembly, a series of residues for substitution were predicted based on crystal structures of BTV type 10 VP7 molecule targeting the monomer-monomer contacts within the trimer. Seven site-specific substitution mutations of VP7 have been created using cDNA clones and were employed to produce seven recombinant baculoviruses. The effects of these mutations on VP7 solubility, ability to trimerize and formation of core-like particles (CLPs) in the presence of the scaffolding VP3 protein, were investigated. Of the seven VP7 mutants examined, three severely affected the stability of CLP, while two other mutants had lesser effect on CLP stability. Only one mutant had no apparent effect on the formation of the stable capsid. One mutant in which the conserved tyrosine at residue 271 (lower domain helix 6) was replaced by arginine formed insoluble aggregates, implying an effect in the folding of the molecule despite the prediction that such a change would be accommodated. All six soluble VP7 mutants were purified, and their ability to trimerize was examined. All mutants, including those that did not form stable CLPs, assembled into stable trimers, implying that single substitution may not be sufficient to perturb the complex monomer-monomer contacts, although subtle changes within the VP7 trimer could destabilize the core. The study highlights some of the key residues that are crucial for BTV core assembly and illustrates how the structure of VP7 in isolation underrepresents the dynamic nature of the assembly process at the biological level.

Amino Acid Sequence↗
PubMed2000

Institutional care: risk from family background or pattern of rearing?

Previous research has shown that children receiving substitute parental care tend to have high rates of emotional/behavioural disturbance, but uncertainty remains on the extent to which this derives from genetic risk, adverse experiences before receiving substitute care, or from risks associated with substitute care experiences. In order to examine the effects of institutional rearing (as a specific form of substitute care), two groups of primary school children reared in substitute care from before the age of 12 months were compared: 19 children in residential group (institutional) care and 19 in continuous stable foster family care (matched for age and gender). The two groups were similar in coming from biological families with high rates of psychopathology and social malfunctioning, but differed with respect to pattern of rearing. Both groups were compared with classroom controls, using teacher questionnaires, systematic classroom observations, and standardised cognitive testing. Parental questionnaires were also obtained for the two substitute care groups. As found previously, the combined substitute care groups differed from controls in showing a high level of hyperactivity/inattention. The observational measures showed a similar effect, indicating that the elevated rate was not attributable to rater bias. The teacher questionnaire and observational measures showed, however, that the increased level of hyperactivity/ inattention was substantially higher in the institutional group than the foster family group. Parental questionnaire ratings showed the same contrast between the groups, except that the main difference was on unsociability and emotional disturbance rather than hyperactivity/ inattention. It is concluded that, against a background of genetic and early environmental risk, institutional rearing predisposes to a pattern of hyperactivity/inattention.

Attention Deficit Disorder with Hyperactivity↗
PubMed2000

Meningococcal meningitis outbreak control strategies.

Meningococcal meningitis has been occurring worldwide in both endemic and epidemic forms. Serogroup A accounts for majority of cases of epidemic as well as endemic Meningococcal meningitis in developing nations, whereas group C and group B causes epidemic and endemic meningococcal meningitis in developed countries. Person to person spread of N. meningitides generally occurs through inhalation of droplets of infected nasopharyngeal secretions by direct or indirect oral contact. Incubation period varies from 2 to 10 days. N. meningitides typically causes acute infective illness characterized by sequential development of upper respiratory tract infection, meningococcemia, meningitis and focal neurological deficit. Over 90 per cent cases of adult meningococcal infections have cerebrospinal meningitis, whereas in children prevalence of meningitis is much lower (50 per cent). Acute meningitis manifests with fever, severe headache, vomiting and neck stiffness. Presentations may be non-specific in infants, elderly and in patients with fulminant meningococcemia. Diagnosis is confirmed with cerebrospinal fluid analysis. Overall mortality due to meningitis is usually around 10 per cent. In meningococcal septicemia, the case fatality rate may exceed 50 per cent. Preventive strategies include vaccination, chemoprophylaxis and early detection and treatment. Mass vaccination campaign, if appropriately carried out, has been documented to halt an epidemic of meningococcal disease due to serogroup A or C. In the present review we have discussed the available evidence with regards to prevention at primary, secondary and tertiary level. Public health approach to an outbreak of meningococcal meningitis in a community or an organization is also outlined.

Disease Outbreaks↗
PubMed1999

Bovine leukemia virus Gag particle assembly in insect cells: formation of chimeric particles by domain-switched leukemia/lentivirus Gag polyprotein.

A key stage in the life cycle of C-type retroviruses is the assembly of Gag precursor protein at the plasma membrane of infected cells. Here we report the assembly of bovine leukemia virus (BLV) gag gene product into virus-like particles (VLPs) using the baculovirus expression system. Expression of BLV Pr44(Gag) resulted in the assembly and release of VLPs, thereby confirming the ability of retroviral Gag polyprotein to assemble and bud from insect cells. Efficient particle formation required a myristoylation signal at the N-terminus of BLV Pr44(Gag). Recombinant baculoviruses expressing matrix (MA) or capsid-nucleocapsid (CA-NC) proteins of BLV were generated but neither of these domains was capable of assembling into particulate structures. To assess the compatibility of Gag domains between leukemia and lentivirus groups three different recombinant chimeras each expressing MA of one virus (e.g., simian immunodeficiency or BLV) and CA-NC of another (e.g., BLV or human T-cell leukemia virus type-I) were constructed. Each of the chimeric proteins assembled efficiently and budded as VLPs, suggesting that the MA and CA domains of these two evolutionary divergent retrovirus groups can be functionally exchanged without perturbation of Gag VLP formation. The lenti-leukemia chimeric Gag approach has potential for studying protein-protein interactions in other retroviruses.

Animals↗
PubMed1999

Efficacy of an inactivated oil emulsion vaccine against hydropericardium syndrome in broilers.

Two inactivated vaccines were prepared against hydropericardium syndrome. The vaccine prepared from liver homogenate extracted with chloroform, inactivated with formalin and adjuvanted with liquid paraffin was highly effective against challenge in chickens aged three, five and seven weeks. Seroconversion following vaccination and challenge was assessed by the agar gel immunodiffusion test. The inactivated oil emulsion vaccine was highly effective against the syndrome in both experimental trials and field trials.

Adenoviridae Infections↗
PubMed1999

Efficacy of live adjuvanted mesogenic Newcastle disease vaccine in chickens.

120 white leghorn chickens primed with a lentogenic Newcastle disease (ND) live vaccine at 7 days of age were divided into three equal groups of 8 weeks of age and vaccinated with a live mesogenic ND vaccine (NDV). One group received only Newcastle disease mesogenic vaccine (RDVK) in normal saline, the second group received RDVK with groundnut oil as adjuvant and the third group received RDVK with liquid paraffin as adjuvant. Sera were collected at different time points for the assessment of antibody level against ND virus (NDV) by the haemagglutination inhibition (HI) test. The commonly used non-adjuvanted RDVK could not evince 100% protective HI titre beyond 11 weeks of age but in both the adjuvanted groups 100% protective HI titre was evident up to 20 weeks of age. On challenge at 20 weeks of age both the adjuvanted groups withstood challenge but in the non-adjuvanted group 80% of chickens withstood the challenge. A significant difference in immune response between the adjuvanted and non-adjuvanted groups was seen but not between both the adjuvanted groups. The advantage of vegetable oil (groundnut oil) as an adjuvant for live mesogenic ND vaccine has been discussed.

Adjuvants, Immunologic↗
PubMed1999

Exertion of tractional force requires the coordinated up-regulation of cell contractility and adhesion.

Although it is understood that cells exert mechanical forces on the extracellular matrix to promote structural organization, the exact mechanism of force transduction is not clearly understood. Using an in vitro force measurement assay, we evaluated two opposing conditions that inhibit or promote matrix organization by fibroblasts: serum deprivation and lysophosphatidic acid stimulation. Under serum deprivation, in spite of significant cell spreading and pseudopodial motility, rabbit corneal fibroblasts generated little or no force on the matrix within 2 h of observation. Lysophosphatidic acid stimulation of serum-starved cells caused dramatic cell contraction (within 2 min), which correlated temporally with a rapid increase in the tractional force generation on the matrix (0.52 x 10(-7) - 1.9 x 10(-7) N; n = 7 experiments). No cell translocation was observed during the period of force generation in response to lysophosphatidic acid-stimulation. These findings, taken together with a concomitant up-regulation of stress fibers in lysophosphatidic acid stimulated fibroblasts, indicate that contractility of non-motile cells involved in forming stress fibers and strong cell-matrix adhesion is the principal force-generating mechanism involved in matrix organization.

Actins↗
PubMed1999

Dot-enzyme linked immunosorbent assay for demonstration of Newcastle disease virus infection.

Dot-enzyme linked immunosorbent assay (ELISA) was standardised to detect Newcastle disease virus (NDV) specific antigen in chicken tissues, embryos and allantoic fluid samples. Samples positive by virus isolation were also found positive by haemagglutination (HA) and haemagglutination inhibition (HI) tests and by dot-ELISA but negative samples were found negative by all the serological tests used. Dot-ELISA was able to detect 0.25-0.50 HA units of virus. The emerging utility of dot-ELISA for diagnosis of Newcastle disease virus infection has been discussed.

Animals↗
PubMed1999

Effect of pressure on antigen-antibody complexes: modulation by temperature and ionic strength.

Changes in the equilibrium binding affinity of antigen-antibody complexes subjected to hydrostatic pressures of about 2000 bar provide a potential means for the separation and recovery under mild conditions of biological molecules from immunoadsorbents or immunosensors. We have investigated the ability of temperature and ionic strength to modulate the pressure sensitivity of several antigen-antibody complexes in solution. For two different protein:monoclonal antibody complexes (BSA:9.1 and HEWL:HyHEL-10) exhibiting pressure-induced dissociation (positive association volume), we find little temperature dependence to the association volume. For another complex (digoxigenin:26-10) exhibiting pressure-induced association, the association volume increases with temperature, which, via a Maxwell relation, indicates that enthalpic changes drive the pressure effect. An increase in ionic strength decreases the affinity of binding the HEWL:HyHEL-5 complex, which contains several salt bridges. At low ionic strengths (<0.3 M), no pressure dependence of the free energy of association is observed, but at higher ionic strengths, significant pressure-induced association is observed, suggesting that positive contributions to the association volume provided by the salt bridges are counterbalanced by other (e.g., aromatic stacking) interactions that lead to negative association volumes. These results suggest that ionic strength may be used to modulate the pressure sensitivity of antigen antibody complexes, which may be useful in designing processes that exploit this phenomenon for immunoseparations.

Animals↗