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Biomedical subjects

D Roy

Publications and source records attributed to D Roy.

At least 19 recordsLinked to original sources
PubMed2007

Observations on juvenile myoclonic epilepsy amongst ethnic Bengalees in West Bengal--an Eastern Indian State.

BACKGROUND: Juvenile myoclonic epilepsy (JME) is not too uncommonly encountered in Indian neurological practice. A number of reports from different parts of India have documented the clinical phenomenology and EEG characteristics of this genetically determined epileptic syndrome. However, no study has yet been reported from the Eastern part of India and none done so far in patients in a specific ethnic group. Furthermore therapy response and follow up data are not available in detail in the Indian studies. OBJECTIVE: To study disease expression, EEG characteristics and therapy response of JME patients in ethnic Bengalees in West Bengal, an Eastern Indian State, in a clinic based study. MATERIAL AND METHODS: 200 patients with JME attending the Neurology Department of the Institute have been followed up for 5 years and different parameters of disease expression as outlined above have been studied. RESULTS: Overall clinical disease expression has been found to be similar in this clinic based study in ethnic Bengalees as compared to other reports from India and elsewhere. About 16% of patients showed a relative resistance to Valproate therapy. Hundred percent of patients in whom therapy withdrawal was attempted, relapsed within<1-2 years. Amongst female patients (132), 16 developed features of polycystic ovarian syndrome while on Valproate therapy. In over half of them, the symptoms regressed after successful switch over from Valproate to Clobazam. 12/132 female patients became pregnant during follow up and while on Valproate; teratogenic effect was evident in only one such patient. CONCLUSIONS: Phenotypic variations in disease expression including therapy response have been noted within a single ethnic group of patients attending the clinic and might account for genetic heterogeneity noted in molecular genetic studies. JME cannot really be called a very 'benign' epileptic syndrome; recurrence after therapy withdrawal almost invariably occurs.

Abnormalities, Drug-Induced↗
PubMed2006

Effects of KI encapsulation in single-walled carbon nanotubes by Raman and optical absorption spectroscopy.

The effect of KI encapsulation in narrow (HiPCO) single-walled carbon nanotubes is studied via Raman spectroscopy and optical absorption. The analysis of the data explores the interplay between strain and structural modifications, bond-length changes, charge transfer, and electronic density of states. KI encapsulation appears to be consistent with both charge transfer and strain that shrink both the C-C bonds and the overall nanotube along the axial direction. The charge transfer in larger semiconducting nanotubes is low and comparable with some cases of electrochemical doping, while optical transitions between pairs of singularities of the density of states are quenched for narrow metallic nanotubes. Stronger changes in the density of states occur in some energy ranges and are attributed to polarization van der Waals interactions caused by the ionic encapsulate. Unlike doping with other species, such as atoms and small molecules, encapsulation of inorganic compounds via the molten-phase route provides stable effects due to maximal occupation of the nanotube inner space.

Journal Article↗
PubMed2006

Combining impedance spectroscopy with cyclic voltammetry: measurement and analysis of kinetic parameters for faradaic and nonfaradaic reactions on thin-film gold.

The technique of time-resolved impedance spectroscopy can be combined with dc cyclic voltammetry (CV) to study mechanisms and kinetics of electrochemical reactions at solid-liquid interfaces. Utilization of these techniques in a combined framework, however, is based on a number of specific considerations of measurement procedures and data analysis. The present work discusses certain essential elements of this topic, focusing primarily on the analysis of time-resolved impedance spectra where interdependent dc and ac effects of parallel faradaic and nonfaradaic reactions are present under potentiodynamic conditions. A thin gold film is used as a model experimental system where oxidation and reduction of the sample surface is voltage-controlled both in the presence and in the absence of specifically adsorbing Cl- ions in neutral background electrolytes of NaF. Impedance spectra are recorded under transient conditions of CV, and kinetic parameters based on electrode-equivalent circuit models are obtained as functions of CV scans.

Gold↗
PubMed2006

SKCG-1: a new candidate growth regulatory gene at chromosome 11q23.2 in human sporadic Wilms tumours.

Using arbitrary primed-PCR (AP-PCR), we have identified a novel genetic alteration located at chromosome 11q23.2 and this genetic alteration was common in 38% of the human Wilms tumour samples analysed. Further characterisation by cloning and sequencing of this genomic region revealed that it represents a part of an uncharacterised gene. We have named this gene as Sporadic Kidney Cancer Gene-1 (SKCG-1). Using fluorescence in situ hybridisation (FISH) approach, we established its localisation on the chromosome 11q23.2. Northern analysis revealed the transcript size of SKCG-1 of 2.09 kb and this was further confirmed by full-length cDNA sequence. Sequence analysis revealed an active translation start site (ATG sequence), a polyadenylation signal sequence (AATAAA), and an open reading frame (ORF) encoding a peptide of 124 amino acids in the cDNA sequence of SKCG-1. Analysis of genomic sequence of SKCG-1 revealed a promoter region containing TATA box located at -13 bp upstream of transcription start site. The AP-PCR, SCAR, and Southern blot analyses indicated genomic loss of SKCG-1 in Wilms tumours. The transcript of SKCG-1 was abundantly present in brain, kidney, liver, testis, salivary gland, foetal brain, foetal liver, whereas relatively lower expression in heart, stomach, prostate and no expression in spleen, colon, lung, small intestine, muscle, adrenal gland, uterus, skin, PBL, and bone marrow was detected. The expression of this gene transcript was either very less or undetectable in Wilms and breast tumours compared to their matched uninvolved tissues. Inhibition of SKCG-1 by siRNA resulted in increased cell proliferation of kidney epithelial cells. Based on the presence of two transmembrane regions in its peptide, SKCG-1 has been predicted as a transmembrane protein. Thus, the findings of this study revealed (i) SKCG-1, a new gene located at 11q23.2 and harbouring genetic alteration in Wilms tumours, (ii) the presence of SKCG-1 gene transcripts in various human normal tissues and its lower expression or absence in Wilms and breast tumours indicate that it may be associated with tumour growth suppressor activity, (iii) the presence of an open reading frame in the cDNA sequence of SKCG-1 indicates that it has potential to encode a protein, (iv) increased cell growth by silencing this gene in HEK293 cells further supports a potential role of this gene in growth of kidney epithelial cells. Our findings suggest that SKCG-1 may have a tumour suppressor role, and implicate genetic alteration in this gene as a potential oncogenic pathway and therapeutic target in kidney and breast cancer.

Amino Acid Sequence↗
PubMed2006

Compositions of maple sap microflora and collection system biofilms evaluated by scanning electron microscopy and denaturing gradient gel electrophoresis.

The bacterial microflora of maple sap and biofilms in collection system tubing were studied through the use of bacterial counts, scanning electron microscopy (SEM) of surfaces and the analysis of 16S rRNA gene by denaturing gradient gel electrophoresis (DGGE). Samples were taken at five times during the 2002 and 2003 seasons in order to follow the changes in the microflora of this complex ecosystem. Bacterial counts showed the growth of bacterial populations as the season advanced. These populations were mainly composed of psychrotrophic bacteria and Pseudomonas spp. SEM results confirmed the suspected presence of biofilms on the inner surfaces of tubing samples. Bacterial colonization and biofilm formation progressively increased during the season for both lateral and main line surfaces, and biofilms were mainly composed of rod shape bacteria. The bacterial microflora profiles obtained for sap and corresponding biofilm by DGGE showed up to 12 major bands. The Shannon-Weaver index of diversity (H) calculated from DGGE bands were statistically higher for sap samples compared to biofilm. The diversity index was relatively stable or increasing for lateral line sap and biofilm samples during the season while the diversity index for sap and biofilm samples of the main line showed a decreasing profile as the season progressed. Sequence analysis of major DGGE bands revealed the predominance of bacteria from the genera Pseudomonas, Rahnella and another, unidentified genus. The results describe the composition of sap collection system microflora as well as the formation of biofilms and will be useful for further studies on factors affecting maple product quality.

Acer↗
PubMed2006

Tamoxifen therapy in encapsulating sclerosing peritonitis in patients after kidney transplantation.

Sclerosing encapsulating peritonitis (SEP) is a serious complication of long-term continuous ambulatory peritoneal dialysis (CAPD) associated with obstructive symptoms and sclerosis of the peritoneal membrane. We present two cases that were successfully treated with tamoxifen and corticosteroids. Case 1: A 40-year-old patient developed end-stage renal failure (ESRF) and was managed with CAPD. He was hospitalized with symptoms of small bowel obstruction. He underwent laparotomy confirming the diagnosis of SEP. The patient was given tamoxifen 20 mg twice a day. Case 2: A 55-year-old patient with ESRF secondary to membranous glomerulonephritis. After having a cadaveric renal transplant in 1978 that failed 20 years later, the patient returned to CAPD. Six years later he had an uneventful kidney transplant and the peritoneal dialysis catheter was removed. However, 8 months later he presented with symptoms of small bowel obstruction and gross blood stained ascites. He also underwent a laparotomy that confirmed the diagnosis of SEP after biopsy. The patient was started on 20 mg of tamoxifen twice a day. Both patients' symptoms were improved gradually with an increase of serum albumin and body weight. Tamoxifen may be useful in the treatment of patients diagnosed with SEP.

Adult↗
PubMed2006

Growth factor biomarkers associated with estrogen- and radiation-induced breast cancer progression.

Breast cancer is the most common cancer in women worldwide. Transformation of a normal cell to a malignant one results from mutations in genes that encode key regulatory proteins. Growth factors are proteins secreted by a variety of transformed cells and tumors and function as autocrine regulators of growth. Biomarkers associated with cancer were examined in human breast epithelial cells transformed by high-LET radiation in the presence of 17beta-estradiol. An established cancer model was used in these studies. The MCF-10F cells that were irradiated with double doses of alpha-particles in the presence of estrogen (60 cGy + E/60 cGy + E, named Alpha 5) showed gradual phenotypic changes relative to control, including tumorigenicity in heterologous animals. Protein expression was determined by quantification of immunofluorescence staining coupled with confocal microscopy. The transforming growth factor alpha, epidermal growth factor, ERK1 and fibroblast growth factor-1 (Int2) protein expression was analyzed. Increased protein expression was observed in non-tumorigenic and tumorigenic alpha-irradiated and estrogen-treated cells. However, Stat-1alpha and pS2 protein expression was only increased in the tumorigenic Alpha 5 and Tumor 2 cell lines. It can be concluded that high-LET radiation in the presence of estrogen-induced changes in the proteins associated with growth factors and their overexpression may be a critical step in the cascade of events that characterize progression in breast cancer.

Biomarkers↗
PubMed2006

Allelic imbalance at 11q23-q24 chromosome associated with estrogen and radiation-induced breast cancer progression.

Multiple genetic alterations are common in cancers including those of the breast. The mechanisms leading to these alterations such as point mutations, gene amplifications, deletions and replication error are often associated with frequent and consistent loss of heterozygosity (LOH) or microsatellite instability (MSI). Several cytological and molecular studies have shown high frequency loss of genetic information on the long arm of chromosome 11 (i.e., 11q) in various primary breast cancers. In the present study allelic alterations in a refined position on the long arm of chromosome 11 were studied to identify the spectrum of induced damage at different stages of malignant transformation of MCF-10F cell lines after exposure to high-LET radiation using alpha-particles and exposure to estradiol by using PCR-single strand conformation polymorphism (SSCP) and fluorescence in situ hybridization (FISH) analysis. Microsatellite markers were selected from chromosome 11 (11q23-q24 loci) and it was found that frequency of allelic imbalance occurs at different stages of tumor progression with a range of 15-45% depending on the marker studied. These results strongly suggested the presence of several tumor suppressor genes in this critical region of chromosome 11 (11q23-q24). It also represents the first indication of allele loss at these loci in human breast epithelial cells induced by radiation and estrogen treatment suggesting a potential interventional target in breast carcinogenesis.

Alpha Particles↗
PubMed2006

Biofilm formation and biocides sensitivity of Pseudomonas marginalis isolated from a maple sap collection system.

The susceptibility of planktonic and biofilm cells of Pseudomonas marginalis toward four commonly used biocides at different temperatures (15 and 30 degrees C) and biofilm growth times (24 and 48 h) was assessed. Using the MBEC biofilm device, biofilm production in maple sap was shown to be highly reproducible for each set of conditions tested. Biofilm formation was influenced by growth temperature and time. A temperature of 15 degrees C and incubation time of 24 h yielded fewer CFU per peg and showed fewer adhered cells and typical biofilm structures, based on scanning electron microscopy observations as compared with other conditions. Minimal biofilm eradication concentration values for P. marginalis were significantly greater (P. < 0.001) than were MBCs for planktonic cells and for every biocide tested, with the exception of minimal biofilm eradication concentration values for peracetic acid at 15 degrees C and 24 h. Sodium hypochlorite and peracetic acid sanitizers were able to eliminate P. marginalis biofilms at lower concentrations as compared with hydrogen peroxide- and quaternary ammonium-based sanitizers (P < 0.001). According to the results obtained, sodium hypochlorite and peracetic acid sanitizers would be more appropriate for maple sap collection system sanitation.

Acer↗
PubMed2005

Surface-enhanced infrared ellipsometry of self-assembled undecanethiol and dodecanethiol monolayers on disordered gold nanoisland substrates.

Infrared spectroscopic ellipsometry (IRSE) is a powerful optical probe of various chemical and physical properties of molecules adsorbed onto solid surfaces. In particular, IRSE can be useful for detecting adsorption-induced changes in the IR spectra of self-assembled monolayers (SAMs), and unlike traditional IR absorption spectroscopies, IRSE provides useful information about the phase of the reflected radiation from the SAMs. However, in the standard IRSE experimental geometry using flat substrates for SAMs, the detectable signal containing these phase data is considerably weaker than the corresponding absorbance data. In our present work, we demonstrate that enhancing the local optical fields at the sample surface through the use of a disordered Au nanoisland substrate can substantially increase both these absorbance and phase signals. We also demonstrate how this surface-enhanced infrared spectroscopic ellipsometry (SEIRSE) can be utilized for straightforward analysis of absorption peak widths, as well as to obtain information about the orientation of the terminal methyl on adsorbed SAMs. As model SAMs for this study, we use undecanethiol (UDT) containing 10 CH(2) units and a terminal CH(3) group, as well as dodecanethiol (DDT) containing 11 CH(2) units with its terminal CH(3) at a different orientation than UDT. We show that surface-enhanced IRSE is sensitive to subtle vibrational signatures of the differently oriented terminal methyls of these two homologous alkanethiol SAMs.

Journal Article↗
PubMed2005

Depopulated bovine ureteric xenograft for complex haemodialysis vascular access.

OBJECTIVES: To assess performance of a de-cellularised bovine ureter vascular graft for haemodialysis in patients for whom conventional access was not possible. METHODS: The Syner Graft Vascular Graft Model 100 (SGVG 100) is a bovine ureter modified by a tissue-engineering depopulation technology and uniquely it is not chemically cross-linked. SGVG 100 was implanted in patients with a failed fistula or vascular access grafts. Graft patency was the primary outcome; secondary outcomes included adverse events and associated treatments. RESULTS: 25 SGVG 100 were implanted in 23 patients; mean age was 59+/-14 years. Mean follow-up was 370 days. The mean time to occlusion (19 events) was 215+/-141 days with patency re-established in 14 of 18 surgical interventions. Thirty angioplasties were performed on 14 SGVG 100 for luminal/anastomotic stenosis. Two grafts demonstrated areas of dilation; however, both grafts continue to be usable at last reported follow-up (930 and 602 days) with no further changes in graft size. Primary patency, assisted primary patency, secondary patency, and freedom from infection were 29, 45, 81, and 95% at 1 year, respectively. CONCLUSIONS: This report demonstrates SGVG 100 is a stable vascular access conduit, providing a suitable graft alternative when autologous vein is not available.

Adult↗
PubMed2005

Comparative analysis of the exopolysaccharide biosynthesis gene clusters from four strains of Lactobacillus rhamnosus.

The exopolysaccharide (EPS) biosynthesis gene clusters of four Lactobacillus rhamnosus strains consist of chromosomal DNA regions of 18.5 kb encoding 17 ORFs that are highly similar among the strains. However, under identical conditions, EPS production varies considerably among these strains, from 61 to 1611 mg l(-1). Fifteen genes are co-transcribed starting from the first promoter upstream of wzd. Nevertheless, five transcription start sites were identified by 5'-RACE PCR analysis, and these were associated with promoter sequences upstream of wzd, rmlA, welE, wzr and wzb. Six potential glycosyltransferase genes were identified that account for the assembly of the heptasaccharide repeat unit containing an unusually high proportion of rhamnose. Four genes involved in the biosynthesis of the sugar nucleotide precursor dTDP-L-rhamnose were identified in the EPS biosynthesis locus, which is unusual for lactic acid bacteria. These four genes are expressed from their own promoter (P2), as well as co-transcribed with the upstream EPS genes, resulting in coordinated production of the rhamnose precursor with the enzymes involved in EPS biosynthesis. This is believed to be the first report demonstrating that the sequence, original organization and transcription of genes encoding EPS production are highly similar among four strains of Lb. rhamnosus, and do not vary with the amount of EPS produced.

Base Sequence↗
PubMed2005

An excess of widespread pain among South Asians: are low levels of vitamin D implicated?

BACKGROUND: Anecdotal reports from rheumatologists in the United Kingdom suggest that patients from South Asian backgrounds are more likely to report widespread body pain. OBJECTIVE: To confirm the presence of an excess of widespread pain in South Asians, and to evaluate the relationship of their symptoms with levels of 25-OH vitamin D. METHODS: Two population studies involving over 3135 subjects were carried out in the North West and Midlands areas of England. RESULTS: The first study confirmed an excess of widespread pain among South Asians (OR = 1.6, 95% CI 1.3 to 2.1). The second smaller study conducted only among young women also showed a similar excess of widespread pain among South Asians (OR = 1.8, 95% CI 0.7 to 4.7) and found that low levels of 25-OH vitamin D (<10 ng/ml) were more common among those with widespread pain (OR = 3.5, 95% CI 0.4 to 31.0). CONCLUSIONS: Owing to the small numbers, the relationship between 25-OH vitamin D and widespread pain must be considered preliminary and requires further investigation. However, it may be one potentially treatable cause of widespread pain.

Adolescent↗
PubMed2005

Differential gene expression of sulindac-treated human breast epithelial cells.

Breast cancer is the most common malignancy and the second major cause of cancer-related deaths among women in the United States. Recent advances in the molecular genetics of breast cancer have identified various genes associated with tumorigenesis. There is evidence that non-steroidal anti-inflammatory drugs, e.g. sulindac, have some anti-proliferative effects on various tumors involving altered p53 function. Most of these studies have been performed with various human colon carcinoma cell lines and few of them focus on non-malignant proliferative human mammary epithelial cell lines. Therefore, the present study was undertaken to analyze the differentially expressed genes of the p53 signaling pathway by means of a gene array for the immortalized human breast epithelial cell line, MCF-10F, treated with sulindac. Out of the total 96 genes, only 17 were altered by the drug treatment. Among these 17 genes, 6 showed significant alteration (Q > 2.0), whereas 11 genes showed moderate alterations. Altered genes included BRCA1 associated protein-1 [ubiquitin carboxy-terminal hydrolase (bap1)]; cell division cycle 2, G1 to S and G2 to M [cdk1(cdc2)]; and DNA-damage-inducible transcript 1 (gadd45), which were down-regulated. However, N-myc gene 1 (rtp), promyelocytic leukemia (pml), and nuclear factor of kappa-light polypeptide gene enhancer in B-cell 3 and p65 [avian (rel A)] were up-regulated. Northern blot analysis confirmed some of these alterations. The alteration of p53 signaling pathway gene markers by sulindac treatment can give us valuable information about the response to drug treatments in a proliferative cell population.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Electricity and the heart.

Understanding of cardiac rhythm requires application of physical principles governing electricity. Over a period of more than 100 years, application of the knowledge of electric current led to the gradual evolution of electrocardiogram, pacemaker, defibrillator, and ultimately electrophysiology. The discovery of electrocardiogram (ECG) by Einthoven in 1902 and that of pacing by Zoll in 1952 were two landmarks in this field.

Animals↗
PubMed2004

Ammonia emission and deposition in Scotland and its potential environmental impacts.

The main source of atmospheric ammonia (NH3) in Scotland is livestock agriculture, which accounts for 85% of emissions. The local magnitude of emissions therefore depends on livestock density, type, and management, with major differences occurring in various parts of Scotland. Local differences in agricultural activities therefore result in a wide range of NH3 emissions, ranging from less than 0.2 kg N ha(-1) year(-1) in remote areas of the Scottish Highlands to over 100 kg N ha(-1) year-1 in areas with intensive poultry farming. Scotland can be divided loosely into upland and lowland areas, with NH3 emission being less than and more than 5 kg N ha(-1) year(-1), respectively. Many semi-natural ecosystems in Scotland are vulnerable to nitrogen deposition, including bogs, moorlands, and the woodland ground flora. Because NH3 emissions occur in the rural environment, the local deposition to sensitive ecosystems may be large, making it essential to assess the spatial distribution of NH3 emissions and deposition. A spatial model is applied here to map NH3 emissions and these estimates are applied in atmospheric dispersion and deposition models to estimate atmospheric concentrations of NH3 and NH4+, dry deposition of NH3, and wet deposition of NHx. Although there is a high level of local variability, modelled NH3 concentrations show good agreement with the National Ammonia Monitoring Network, while wet deposition is largest at high altitude sites in the south and west of Scotland. Comparison of the modelled NHx deposition fields with estimated thresholds for environmental effects ("critical loads") shows that thresholds are exceeded across most of lowland Scotland and the Southern Uplands. Only in the cleanest parts of the north and west is nitrogen deposition not a cause for concern. Given that the most intense effects occur within a few kilometres of sources, it is suggested that local spatial abatement policies would be a useful complement to traditional policies that mitigate environmental effects based on emission reduction technologies.

Ammonia↗
PubMed2004

Toxicological effects of malachite green.

This review summarises the wide range of toxicological effects of malachite green (MG), a triarylmethane dye on various fish species and certain mammals. MG is widely used in aquaculture as a parasiticide and in food, health, textile and other industries for one or the other purposes. It controls fungal attacks, protozoan infections and some other diseases caused by helminths on a wide variety of fish and other aquatic organisms. However, the dye has generated much concern regarding its use, due to its reported toxic effects. The toxicity of this dye increases with exposure time, temperature and concentration. It has been reported to cause carcinogenesis, mutagenesis, chromosomal fractures, teratogenecity and respiratory toxicity. Histopathological effects of MG include multi-organ tissue injury. Significant alterations occur in biochemical parameters of blood in MG exposed fish. Residues of MG and its reduced form, leucomalachite green have been reported from serum, liver, kidney, muscles and other tissues as also from eggs and fry. Toxicity occurs in some mammals, including organ damage, mutagenic, carcinogenic and developmental abnormalities. However, despite the large amount of data on its toxic effects, MG is still used as a parasiticide in aquaculture and other industries. It is concluded that the potential of alternative parasiticides, like humic acid, chlorine dioxide and Pyceze, should be explored to replace MG. Until then, MG should be used with extreme care at suitable concentrations and at times when the temperature is low. Removal of residual MG in treatment ponds should also be considered.

Aniline Compounds↗