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Biomedical subjects

S Roy

Publications and source records attributed to S Roy.

At least 55 records · Page 3Linked to original sources
PubMed2005

An isolated osteochondroma with underlying non-Hodgkin's lymphoma of bone.

Osteochondroma is the most common benign bone tumour. The risk of sarcomatous change in an isolated lesion is approximately 1%. We report a case of an isolated osteochondroma which appeared benign on clinical and plain radiographic examination but routine histological analysis revealed non-Hodgkin's lymphoma in the underlying bone. This association has not previously been reported and the case emphasises the importance of routine histological analysis, even if a lesion appears benign.

Adult↗
PubMed2005

Identification of a heterodimer-specific epitope present in human chorionic gonadotrophin (hCG) using a monoclonal antibody that can distinguish between hCG and human LH.

Human chorionic gonadotrophin (hCG) is secreted during early pregnancy and is required for implantation and maintenance of the pregnancy. Active or passive immunoneutralization of hCG results in termination of pregnancy and this forms the basis of the hCG-based female contraceptive vaccine. However, the beta subunit of hCG possesses 85% sequence homology with the first 114 amino acids of the beta subunit of pituitary human LH (hLH), which is required for ovulation and maintenance of the corpus luteum function during the menstrual cycle. Immunization against hCG or its beta subunit leads to generation of antibodies that can neutralize hLH due to many shared epitopes and hence may cause abnormal menstrual cycles. Therefore, it is essential to identify epitopes that are different in the two hormones. In the present study, we report a monoclonal antibody (MAb) specific for hCG that shows no binding to the isolated subunits. Interestingly, the MAb also does not bind hLH at all. The epitope mapping analysis revealed that this antibody recognizes a unique discontinuous epitope present only in the heterodimeric hCG and is distinct from the unique C-terminal extension of hCG beta that is absent in hLH beta. The MAb, either as IgG or its recombinant single-chain variable region fragment, inhibited the response to hCG, but not to hLH. Thus, the epitope recognized by this MAb is an ideal candidate antigen for immunocontraception.

Amino Acid Sequence↗
PubMed2005

[Cultural diversity in Montreal: a range of public health challenges].

Increasing immigration to Quebec has brought to the surface the need for adapting its public health systems and services, particularly in the area of primary care. The challenge is to take the heterogeneous nature of the population into account and to integrate diverse values, experience and know-how into the development of programmes and delivery of services, whilst simultaneously respecting the values of the various care providers and the norms of the institutions in the host country. This article addresses the question of adaptation strategies for health services, and namely the development of prevention and heath promotion programmes in public health within the framework of primary health care services within the intercultural context of Montreal. The issue of adaptation falls within the perspective and mandate of the Quebec government's policy on health and well-being (La politique de santé et du bien-être, 1992). Furthermore, it is a response to frequent demands from various health professionals and groups concerned with the adaptation of public services with respect to intercultural relationships confronted with the emerging realities associated with immigration. The article provides a reflection on specific ways of adapting prevention and health promotion initiatives targeting cultural communities and those who are undergoing immigration procedures or transitions. It also examines the development of ethno-cultural or other indicators which make it possible to capture migration experiences and their health impact. Since the Quebec health and social services system is currently in the process of major reform, it is hoped that it will seize this opportunity in order to make health and social service centres accountable for the adaptation of their programmes and services to the diversity of the populations they serve.

Cultural Diversity↗
PubMed2005

Comparison of immunoreactive proteins of commonly circulating serogroups of Leptospira in Andaman Islands, India.

BACKGROUND & OBJECTIVE: Early diagnosis is the key to the treatment of leptospirosis. For development of rapid diagnostic kits, a thorough knowledge about the nature of the proteins expressed by the pathogen during infection is necessary. The present study was undertaken to understand the nature of immunoreactive proteins from commonly circulating serogroups of Leptospira in the endemic Andaman and Nicobar Islands, India. METHODS: Proteins were extracted from six strains of Leptospira representing five different serogroups following four different preparation methods, viz., whole cell lysis by sonication, detergent solubilization, outer and inner membrane isolations, and were subsequently characterized on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Immunoblots were made from the sonicated proteins using hyperimmune rabbit antisera, homologous and heterologous patient sera separately. RESULTS: The 67, 65, 45, 43, 35, 32 and 18 kDa major proteins in the whole cell lysate were common among all the five serogroups of Leptospira. The 67, 41, 35, 32, 28 and 22 kDa were the major outer membrane proteins, while 94, 32, 25 and 18 kDa protein were in inner membrane. Immunoblots with hyperimmune rabbit antisera detected 67, 65, 60, 45, 43, 41 and 32 kDa common proteins from the whole cell lysates of all strains while homologous and heterologous patient sera detected 32 kDa as the major immunoreactive protein in all pathogenic serogroups. This protein reacted against specific LipL32 antisera indicating that this protein was LipL32. INTERPRETATION & CONCLUSION: The circulating serogroups of Leptospira have common nature of expression of proteins during human infection. Among several immunoreactive proteins, three (67, 45 and 32 kDa) were recognized as major antigens by both rabbit hyperimmune sera and patients sera while the 32 kDa protein was recognized as the major immunoreactive protein by homologous and heterologous patient sera. These conserved immunoreactive proteins could be utilized in developing indigenous diagnostic tests for leptospirosis.

Animals↗
PubMed2004

Optimisation of the separation of four major neutral glycosphingolipids: application to a rapid and simple detection of urinary globotriaosylceramide in Fabry disease.

A simple method for the separation of the four major neutral glycosphingolipids, present in all human tissue, was developed. This gradient normal phase-HPLC method utilises a polyvinyl alcohol bonded stationary phase and an evaporative light-scattering detection (ELSD). Screening pure solvents in a binary gradient elution mode allowed, in a first step, to assess the behaviour of the studied solutes and to select the solvents for further mobile phase optimisation. The proportion of the remaining solvents was defined to reach a maximal resolution. The reduction of the analysis time and the enhancement of the signal were obtained by optimising the gradient slope and the flow-rate. Optimal levels of triethylamine and formic acid (TEA-FA) for the enhancement of the evaporative light scattering detector response were established at 0.1% (v/v). Thus, the optimal conditions for the separation of the four glycosphingolipids was obtained with a gradient elution from a 100% chloroform to a 100% acetone:methanol (90:10 (v/v)) mobile phase at 0.2 ml min-1, using a 10% min-1 gradient slope. Finally, this method was applied to detect the excess of one of the neutral sphingolipids, namely globotriaosylceramide (Gb3) in the urine of patients affected with Fabry disease. A liquid-liquid extraction of the sediments obtained from an aliquot of only ten ml of urine proved sufficient to detect the excess of Gb3 present in both hemizygote and heterozygote patients. In all, the ability of our method to detect abnormal amounts of Gb3 in urinary sediments could allow the diagnosis of weakly symptomatic Fabry patients in large screening programs

Chromatography, High Pressure Liquid↗
PubMed2004

Inactivation of dispatched 1 by the chameleon mutation disrupts Hedgehog signalling in the zebrafish embryo.

Searches of zebrafish EST and whole genome shotgun sequence databases for sequences encoding the sterol-sensing domain (SSD) protein motif identified two sets of DNA sequences with significant homology to the Drosophila dispatched gene required for release of secreted Hedgehog protein. Using morpholino antisense oligonucleotides, we found that inhibition of one of these genes, designated Disp1, results in a phenotype similar to that of the "you-type" mutants, previously implicated in signalling by Hedgehog proteins in the zebrafish embryo. Injection of disp1 mRNA into embryos homozygous for one such mutation, chameleon (con) results in rescue of the mutant phenotype. Radiation hybrid mapping localised disp1 to the same region of LG20 to which the con mutation was mapped by meiotic recombination analysis. Sequence analysis of disp1 cDNA derived from homozygous con mutant embryos revealed that both mutant alleles are associated with premature termination codons in the disp1 coding sequence. By analysing the expression of markers of specific cell types in the neural tube, pancreas and myotome of con mutant and Disp1 morphant embryos, we conclude that Disp1 activity is essential for the secretion of lipid-modified Hh proteins from midline structures.

Amino Acid Sequence↗
PubMed2004

Methylation of the asparagine synthetase promoter in human leukemic cell lines is associated with a specific methyl binding protein.

We have examined the methylation profiles of the asparagine synthetase (ASY) promoter in a number of human leukemic cell lines in relation to their asparagine (ASN) requirements in vitro. Cells in which the promoter is highly methylated are auxotrophs and express ASY at very low levels. Electromobility shift assays (EMSA) of nuclear extracts with oligomers from the promoting region show, in addition to recognized transcription factor binding, a novel methyl binding protein specific for a 12 base consensus sequence, which includes a single methylated CpG. This sequence overlaps that of the amino-acid response unit of the ASY promoter, which is activated byATF4 and C/EBP. Competition by the methyl binding protein could account for the observed failure of the methylated promoter to bind these transcription factors and consequently, although other mechanisms can also be operative, for the specific repression of the gene. The ASY methyl binding protein (ASMB) is present in leukemic lymphoid and myeloid cells irrespective of their methylation status, and in normal lymphocytes after phytohemagglutinin stimulation. It has been purified by affinity chromatography and has a molecular size of 40 kDa in 10% SDS-polyacrylamide gels.

Aspartate-Ammonia Ligase↗
PubMed2004

Simulation of the kinetics of a sphere attached to a fluctuating polymer: Implications for target search by DNA-binding proteins.

We simulate the dynamics of a sphere, bound with a certain probability onto the beads of a harmonic bead-spring polymer in a confined geometry. The sphere hops from ith to the spatially closest i+/-kth bead. There is a crossover between kinetics dominated by different mechanisms with increasing binding probability. We relate these observations to the context of a biologically important problem of target location by DNA-binding proteins within a genome.

Binding Sites↗
PubMed2004

Vaginal pH is similar to follicle-stimulating hormone for menopause diagnosis.

OBJECTIVE: This paper is intended to demonstrate whether vaginal pH value is associated with menopausal status and symptoms, to review the sensitivity of follicle-stimulating hormone or vaginal pH to diagnose menopause, to compare these findings to a group of practice patients, and to determine whether vaginal pH could be used in place of follicle-stimulating hormone as an initial screen to determine menopause. STUDY DESIGN: Sixteen studies regarding vaginal pH and menopausal symptoms before and after estrogen administration were analyzed. Two epidemiologic studies that reported follicle-stimulating hormone or vaginal pH with menopause were reviewed. These findings were compared with similar data from the practice of one of the authors (J.C.C.). RESULTS: Menopausal women who do not receive estrogen therapy have a weighted average vaginal pH of 6.0, which is reduced significantly to 4.5 with estrogen therapy. To diagnose menopause, follicle-stimulating hormone >or=15 or >or=20 mIU/mL in the Third National Health and Nutrition Examination Survey had a sensitivity of 65% to 68%. In a study in Costa Rica, where 3 definitions of menopause were used, a pH of >5.0 had a sensitivity of 64% to 67%. From the practice patients, the 95% confidence interval sensitivities and positive predictive values of vaginal pH and follicle-stimulating hormone to diagnose menopause overlapped, while a pH 4.5 indicates menopause, because it demonstrates a similar sensitivity as follicle-stimulating hormone in epidemiologic studies. In the practice patients, the sensitivity of follicle-stimulating hormone was no different than vaginal pH in the diagnosis of menopause. Furthermore, with estrogen therapy, a vaginal pH of <or=4.5 indicates a mid follicular phase estradiol.

Adult↗
PubMed2004

Effects of fimbria-fornix transection on calpain and choline acetyl transferase activities in the septohippocampal pathway.

The ability of fimbria-fornix bilateral axotomy to elicit calpain and caspase-3 activation in the rat septohippocampal pathway was determined using antibodies that selectively recognize either calpain- or caspase-cleaved products of the cytoskeletal protein alphaII-spectrin. Radioenzymatically determined choline acetyl transferase (ChAT) activity was elevated in the septum at day 5, but reduced in the dorsal hippocampus at days 3, 5 and 7, after axotomy. Prominent accumulation of calpain-, but not caspase-3-, cleaved spectrin proteolytic fragments was observed in both the septum and dorsal hippocampus 1-7 days after axotomy. ChAT-positive neuronal cell bodies in the septum also displayed calpain-cleaved spectrin indicating that calpain activation occurred in cholinergic septal neurons as a consequence of transection of the septohippocampal pathway. Calpain-cleaved alphaII-spectrin immunoreactivity was observed in cholinergic fibers coursing through the fimbria-fornix, but not in pyramidal neurons of the dorsal hippocampus, suggesting that degenerating cholinergic nerve terminals were the source of calpain activity in the dorsal hippocampus following axotomy. Accumulation of calpain-cleaved spectrin proteolytic fragments in the dorsal hippocampus and septum at day 5 after axotomy was reduced by i.c.v. administration of two calpain inhibitors. Calpain inhibition partially reduced the elevation of ChAT activity in the septum produced by transection but failed to decrease the loss of ChAT activity in the dorsal hippocampus following axotomy. These findings suggest that calpain activation contributes to the cholinergic cell body response and hippocampal axonal cytoskeletal degradation produced by transection of the septohippocampal pathway.

Animals↗
PubMed2004

A unique strain of Leptospira isolated from a patient with pulmonary haemorrhages in the Andaman Islands: a proposal of serovar portblairi of serogroup Sehgali.

Leptospirosis is endemic in the Andaman Islands, often occurring as outbreaks during the post-monsoon period. Pulmonary involvement is common and associated with high morbidity and mortality. During the investigation of an outbreak in North Andaman in 1996 an isolate was recovered from the blood of a patient with fever, headache, body aches and haemoptysis with respiratory distress as presenting symptoms. The isolate was characterized using the cross-agglutination absorption test (CAAT) and monoclonal antibodies (mAbs). The isolate showed typical morphology and characteristic motility of the genus Leptospira. Growth was inhibited at 13 degrees C and in the presence of 8-azaguanine. The isolate could not be identified with grouping sera representing 25 serogroups, CAAT and mAbs. A new serovar of a new serogroup is proposed. Genetic characterization using polymerase chain reaction (PCR) followed by sequencing of the PCR product and randomly amplified polymorphic DNA fingerprinting (RAPD) showed that the isolate was genetically similar to L. interrogans sensu stricto.

Adult↗
PubMed2004

Mast cells at the host-pathogen interface: host-protection versus immune evasion in leishmaniasis.

Infection of a susceptible host with Leishmania, a protozoan parasite, causes the disease leishmaniasis, which is characterized by neutrophil, eosinophil, macrophage, lymphocyte and mast cell infiltration into the infected tissue followed by parasite growth. Although the roles played by other cells in leishmaniasis are known, the role of mast cells remains to be ascertained. Here, we demonstrate that Leishmania regulates mast cell infiltration to the site of infection, mast cell production and mast cell function resulting in differential growth of the parasite in resistant (C57BL/6 or CBA/T6T6) and susceptible (BALB/c) macrophages. An interleukin-3-dependent augmentation in mast cell committed progenitors is observed in BALB/c but not in C57BL/6 mice during Leishmania infection. The mast cell supernatants inhibit IFN-gamma-dependent restriction of Leishmania growth in macrophages in BALB/c mice whereas the reverse phenomenon occurs in C57BL/6 mice. Our data reveals a different facet of host-pathogen interaction.

Animals↗
PubMed2004

Human immunodeficiency virus type 1-specific immune responses in primates upon sequential immunization with adenoviral vaccine carriers of human and simian serotypes.

Two triple immunization vaccine regimens with adenoviral vectors with E1 deleted expressing Gag of human immunodeficiency virus type 1 were tested for induction of T- and B-cell-mediated-immune responses in mice and in nonhuman primates. The vaccine carriers were derived from distinct serotypes of human and simian adenoviruses that fail to elicit cross-neutralizing antibodies expected to dampen the effect of booster immunizations. Both triple immunization regimens induced unprecedented frequencies of gamma interferon-producing CD8(+) T cells to Gag in mice and monkeys that remained remarkably stable over time. In addition, monkeys developed Gag-specific interleukin-2-secreting T cells, presumably belonging to the CD4(+) T-cell subset, and antibodies to both Gag and the adenoviral vaccine carriers.

AIDS Vaccines↗
PubMed2004

Blood usage in an Australian intensive care unit: have we met best practice goals?

The transfusion of blood products, especially red cell concentrates, in critically ill patients is controversial and benefits of red cell concentrate transfusion in these patients have not been clearly demonstrated. We performed a prospective observational study to compare best evidence to actual practice of red cell concentrate and other blood product administration in an intensive care unit (ICU) in a university-associated tertiary hospital. All primary admissions during a 28-day period were included in the study and data collected included transfusion of red cells and blood products, patient demographics and ICU and hospital outcome. One hundred and seventy-five admissions were studied; 44% followed cardiac surgery. Forty-one patients (23%) received red cell concentrates in ICU, with 120 units transfused in 61 separate episodes. Other blood product usage was minimal. One third (20/61) of red cell concentrate transfusion episodes were of a single unit. The mean (+/- SD) pre-transfusion haemoglobin was 7.9 +/- 1.1 g/dl. Despite transfusion, such patients left ICU with a lower haemoglobin concentration compared with untransfused ICU patients (9.5 +/- 1.0 versus 10.5 +/- 2.1 g/dl; P < 0.001). Cardiac surgical patients received similar red cell transfusion to general ICU patients. Univariate analysis showed no significant difference in mortality between patients who did or did not receive red cell concentrate transfusion (P = 0.17). However, red cell concentrate transfusion was associated with a reduced adjusted mortality both in ICU (OR 0.13, 95% CI 0.02-0.73) and in hospital at 28 days (OR 0.10, 95% CI 0.02-0.58). The low red cell concentrate and blood product usage in our ICU were consistent with restrictive transfusion practice and selective red cell concentrate transfusion was associated with reduced mortality.

APACHE↗
PubMed2004

Modulation of tumor induced angiogenesis in Ehrlich ascites tumor.

In this study the enzyme glutaminase, purified from the ascites fluid of ovarian cancer patients, was analysed for its antiangiogenic activity. Intraperitoneal administration of this enzyme reduces the number of tumor directed capillaries in solid and ascites tumor bearing Swiss mice induced by transplantation of Ehrlich ascites cells. The enzyme has a critical role in regulating the secretion of vascular endothelial growth factor (VEGF) from tumor cell and in turn tumor growth. Glutamine analogue like 6-diazo, 5- oxo L-norleucine (DON) is also found to be effective in regulating vascular endothelial growth factor (VEGF) secretion from tumor cells in vitro. Treatment with enzyme reduced serum VEGF levels of the tumor induced animals. In vitro VEGF production by EAC cells was reduced in a concentration dependent manner in presence of glutamine analogue.

Animals↗
PubMed2003

Pseudomonas putida as the dominant toluene-degrading bacterial species during air decontamination by biofiltration.

The microbial communities established in three laboratory-scale compost matrix biofilters fed with toluene were characterized. The biofilters were operated for 7 weeks at inlet concentrations of toluene ranging over 250-500 ppm with daily irrigation, using a nutrient solution containing variable concentrations of nitrogen, supplied as urea, and other inorganic salts. The indigenous microflora of the compost included toluene-degrading species, making inoculation unnecessary. The numerically predominant toluene-degrading strains were isolated from the most diluted positive wells of most-probable-number counts on mineral medium with toluene as sole carbon source and identified by rRNA 16S gene sequencing. On the basis of sequence similarity, all the isolated strains were assigned to the species Pseudomonas putida, although some variations were observed in their respective sequences. It is concluded that the mode of biofilter operation including a daily supply of non-carbon nutrients created an environment favoring the constant numerical predominance of this fast-growing toluene-degrading species.

Air Pollutants↗