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Biomedical subjects

S Roy

Publications and source records attributed to S Roy.

At least 73 records · Page 4Linked to original sources
PubMed2003

The benefit of the retrofitting of a conventional LC system to micro LC: a practical evaluation in the field of bioanalysis with fluorimetric detection.

The interests in liquid micro-chromatography (higher column efficiencies, increase in sensitivity) are now well established. The enhancement of fluorimetric response induced by the reduction of the inner diameter of columns (4.6, 3.0, 1.0 and 0.3 mm respectively) coupled with adapted detection cells to control the loss of efficiency (8 micro L for the two first columns and 100 nL for the two smaller ones) has been studied in the bioanalytical field, using the plasma determination of native fluorescent antibacterial agents: fluoroquinolones. Ten-fold enhancement of the signal can easily be obtained when substituting a 0.3 mm i.d. column and 100 nL detection cell for a 4.6 mm i.d. column, and 8 micro L detection cell. In addition to inner diameter reduction, the detection cell geometry appears to be an essential parameter to obtain the best enhancement of the recorded signal. Hence, the enhancement of signal with micro-chromatography with fluorimetric detection appears to be a compromise between column inner diameter and flow cell volume reduction.

Chromatography, Liquid↗
PubMed2003

Evaluation of antipyretic potential of Vernonia cinerea extract in rats.

The methanol extract of the whole plant of Vernonia cinerea (MEVC) was evaluated for its antipyretic potential on normal body temperature and yeast-induced pyrexia in rats. MEVC significantly reduced the normal body temperature at doses of 250 and 500 mg/kg body weight p.o. MEVC also lowered the elevated body temperature in the case of yeast-induced pyrexia in a dose dependent manner. The antipyretic effect of the extract at a dose of 500 mg/kg was identical to that of the standard drug paracetamol.

Administration, Oral↗
PubMed2003

Antimicrobial activity of Andrographis paniculata.

The antimicrobial activity of aqueous extract, andrographolides and arabinogalactan proteins from Andrographis paniculata were evaluated. The aqueous extract showed significant antimicrobial activity, which may be due to the combined effect of the isolated arabinogalactan proteins and andrographolides.

Andrographis↗
PubMed2003

Silicon dermabrasion tools for skin resurfacing applications.

Miniature abrasion tools for potential skin resurfacing applications are created using microelectromechanical systems (MEMS) fabrication technology. The abrading microstructures are formed on silicon wafers by a bulk micromachining process based on isotropic xenon difluoride etching. The micromachined abraders (microdermabraders) are packaged and applied to human cadaveric skin to assess abrasion quality. Plastic (acrylic) microreplicated structures, non-coated and aluminum-coated versions, are also used in a similar fashion. Non-textured silicon and plastic samples are used as study controls. Dermabraded and intact skin regions are analyzed qualitatively and quantitatively by light microscopy, image processing techniques, and histology. The microdermabraders exhibit a cleaner, more uniform abrading pattern on the cadaveric skin compared to the plastic microreplicated structures. Furthermore, the microdermabraders provide a consistently uniform cut through the epidermal layer, leaving little debris and minimal pitting. In contrast, the plastic microreplicated structures exhibit non-uniform abrading patterns and leave behind more debris and eccentric pits. The results suggest micromachined dermabraders can successfully abrade fine dermatological flaws in human skin.

Cadaver↗
PubMed2003

Molecular analysis of Huntington's disease and linked polymorphisms in the Indian population.

OBJECTIVES: To understand the population variation and haplotypes of Huntington's disease (HD) in India we have analysed CAG repeats at the HD locus together with closely linked polymorphisms in both HD patients and normal controls. MATERIALS AND METHODS: The CAG repeat and linked polymorphisms were analysed in 30 Indian HD families together with 250 ethnically matched controls using fluorescent polymerase chain reaction (PCR) based size estimation. RESULTS: CAG repeats at the HD locus in the normal population showed a mean size of 17.99 +/- 2.66 repeats (range nine to 33 repeats). The HD mutation in our families did not show any significant association with either the (CCG)7 or (CCG)10 allele while haplotype analysis suggested the over-representation of the 7-2-I (CCG-D4s127-Delta 2642 loci) haplotype in a subset of families. CONCLUSION: The distribution of CAG repeats in the normal population suggests a higher prevalence of HD, closer to that seen in Western Europe. Haplotype analysis suggests the presence of a founder mutation in a subset of families and provides evidence for multiple and geographically distinct origins for the HD mutation in India.

Female↗
PubMed2003

Urolithiasis in pediatric patients with acute lymphoblastic leukemia.

We evaluated the incidence, timing, and consequences of urolithiasis in children with acute lymphoblastic leukemia (ALL). A total of 20 patients with urolithiasis were identified from 2095 patients with ALL treated at St Jude Children's Research Hospital on consecutive protocols between 1968 and 1998. For remission induction therapy, all patients received daily prednisone; continuation chemotherapy regimens differed by protocol with some including pulses of prednisone or dexamethasone and others no glucocorticoid. Patients with urolithiasis were older at diagnosis of ALL than those without urolithiasis (median age, 7.5 vs 5.0 years; P=0.03) and less likely to be black (P=0.03) than white or Hispanic, but sex and treatment era did not differ. Presenting symptoms included abdominal or flank pain, hematuria, and dysuria. All stones analyzed biochemically were calcium stones. The incidence of urolithiasis after completion of therapy was 1.8 per 10 000 person-years. Compared to this baseline rate, the relative risk of urolithiasis was 45 (P<0.01) during induction therapy, 22 (P<0.01) during continuation therapy with glucocorticoids, and 5.1 (P>0.05) during continuation therapy without glucocorticoids. Urolithiasis occurred 4.5 times more often during continuation treatment with glucocorticoids than without (P<0.05). Seven patients (35%) had recurrent urolithiasis. Patients with ALL are at risk of developing calcium renal stones during chemotherapy, especially when a glucocorticoid is included.

Adolescent↗
PubMed2003

Infection of human mononuclear phagocytes and macrophage-like THP1 cells with Leishmania donovani results in modulation of expression of a subset of chemokines and a chemokine receptor.

The expression of chemokines and chemokine receptors was studied in Leishmania donovani (LD)-infected human mononuclear phagocytes and the human monocytic cell line THP1. Our studies showed that LD infection caused the upregulation of three beta chemokines (macrophage inflammatory protein-1 alpha (MIP-1alpha), MIP-1beta and RANTES (regulated on activation normal T cell expressed and secreted)), one alpha chemokine (interleukin-8 (IL-8)) and the CC chemokine receptor 5 (CCR5) but not CCR1, as evident from reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. The CCR5 upregulation in human mononuclear phagocytes and THP1 cells was also evident by confocal microscopy. The possible association of such upregulation in relation to Leishmania and human immunodeficiency virus (HIV) coinfection was discussed.

Animals↗
PubMed2003

Morphine inhibits VEGF expression in myocardial ischemia.

BACKGROUND: Vascular endothelial growth factor (VEGF) may contribute to the resolution of myocardial ischemia by stimulating collateral circulation. Morphine analgesia after myocardial ischemia is thought to increase infarct size. We hypothesize that morphine inhibits myocardial VEGF expression by inhibiting hypoxia-induced factor 1alpha (HIF-1alpha) and the signal transduction mechanisms involving Erk-1,2 MAP kinase (p42/p44), and PI3 kinase activity (phospho-Akt). METHODS: (1) In vitro: primary cultures of rat cardiac myocytes; (2) in vivo: rat coronary ligation model; (3) mRNA measurement: real-time reverse transcriptase-polymerase chain reaction; (4) protein measurements: enzyme-linked immunosorbent assay, Western immunoblot, electromobility shift assay (EMSA), and immunohistochemistry. RESULTS: Using rat cardiac myocytes in vitro, we show that morphine: (1) decreases hypoxia-induced VEGF(121) and VEGF(165) mRNA expression and VEGF protein concentration through an opioid receptor mechanism; (2) decreases HIF-1alpha protein expression (immunoblot) and nuclear protein binding to the VEGF HIF-1alpha DNA response element (EMSA); and (3) inhibits phospho-Erk-1,2 MAP kinase (immunoblot) and phospho-Akt kinase activity (immunoblot). Using a rat coronary ligation model, we show that morphine treatment: (1) decreases myocardial VEGF protein expression (immunohistochemistry); (2) decreases HIF-1alpha protein expression (immunoblot); and (3) decreases phospho-Erk-1,2 and phospho-Akt expression. CONCLUSIONS: (1) Morphine inhibits hypoxia-induced VEGF transcription, in part, through an HIF-1alpha-mediated mechanism and (2) morphine inhibition of hypoxia-induced HIF-1alpha may be mediated by inhibition of ERK 1,2 MAP kinase activity and PI3 kinase activity.

Animals↗
PubMed2003

Evaluation of anti-inflammatory activity of Vernonia cinerea Less. extract in rats.

The methanol extract of the whole plant of Vernonia cinerea Less. was evaluated for its anti-inflammatory activity in acute (carrageenin, histamine and serotonin induced rat paw edema) and a chronic model (cotton pouch induced granuloma). The methanol extract (250 and 500 mg/kg(-1) p.o.) exhibited significant activity (p < 0.001) against all phlogistic agents used in a dose dependant manner. In the chronic model (cotton pouch granuloma method) the methanol extract exhibited significant anti-inflammatory activity. All these effects were compared with standard drug phenylbutazone (100 mg/kg(-1) p.o.).

Animals↗
PubMed2003

Definition of a VR-based protocol to treat social phobia.

Social phobia is an anxiety disorder that is accessible to two forms of treatment yielding scientifically validated results: drugs and cognitive-behavioral therapies. Graded exposure to feared social situations is fundamental to obtain an improvement of the anxious symptoms. Traditionally, exposure therapies are done either in vivo or by imagining the situations. In vivo exposure is sometimes difficult to control and many patients have some difficulties in using imagination. Virtual reality (VR) seems to bring significant advantages. It allows exposures to numerous and varied situations. This paper reports the definition of a clinical protocol whose purpose is to assess the efficiency of a VR therapy compared to a CBT and to the absence of treatment for social phobic patients. It explains the illness' diagnosis and its usual treatments. It exposes all the architecture of the study, the assessment tools, the content and unfold of the therapy sessions. It finally reports first results of a clinical trial in a between-group design in 10 patients suffering from social phobia. The virtual environments used in the treatment reproduce four situations that social phobics feel the most threatening: performance, intimacy, scrutiny and assertiveness. With the help of the therapist, the patient learns adapted cognitions and behaviors with the aim of reducing her or his anxiety in the corresponding real situations. The novelty of our work is to address a group of situations that the phobic patient is most likely to experience and to treat patients according to a precise protocol.

Adult↗
PubMed2003

The VEPSY UPDATED Project: clinical rationale and technical approach.

More than 10 years ago, Tart (1990) described virtual reality (VR) as a technological model of consciousness offering intriguing possibilities for developing diagnostic, inductive, psychotherapeutic, and training techniques that can extend and supplement current ones. To exploit and understand this potential is the overall goal of the "Telemedicine and Portable Virtual Environment in Clinical Psychology"--VEPSY UPDATED--a European Community-funded research project (IST-2000-25323, www.cybertherapy.info). Particularly, its specific goal is the development of different PC-based virtual reality modules to be used in clinical assessment and treatment of social phobia, panic disorders, male sexual disorders, obesity, and eating disorders. The paper describes the clinical and technical rationale behind the clinical applications developed by the project. Moreover, the paper focuses its analysis on the possible role of VR in clinical psychology and how it can be used for therapeutic change.

Computer Simulation↗
PubMed2003

Infectivity and attenuation of Leishmania donovani promastigotes. II: Association of the loss of parasite infectivity with the terminal galactosylation of precursor acceptors present in virulent parasites by the developmentally regulated galactosyltransferase.

The beta1-4 galactosyltransferase enzyme of the Leishmania donovani promastigotes, was found to be developmentally regulated and expressed only in the attenuated parasites. The enzymatic product of soluble determinants of virulent promastigotes and the galactosyltransferase enzyme was found to stimulate the macrophage burst activity but inhibit in vitro intracellular parasitism. In contrast, removal of terminal galactose moieties from soluble determinants of attenuated parasites resulted in the inhibition of macrophage respiratory burst activity but did not now inhibit intracellular parasitism. We propose that the terminal galactosylation of acceptor substrates present in virulent parasites by the developmentally regulated galactosyltransferase is associated with loss of parasite virulence.

Animals↗
PubMed2003

Magnetic properties of iron nitride-silica nanocomposite materials prepared by high-energy ball milling.

Powder mixtures of (FexN)y and (SiO2)1-y, with x between 3 and 4 and y equal to 0.2 or 0.6, were ball-milled for 4, 8, 16, 32, and 64 h. X-ray diffraction, thermal analysis, and magnetization measurements allowed an investigation of structural and magnetic properties to be carried out. The samples consist of nanostructured Fe3N and Fe4N particles in a SiO2 matrix. As the milling time increases, the Fe4N phase is eliminated from the particles in favor of Fe3N. Coercive fields as high as 270 and 84 Oe are obtained for (FexN)0.2(SiO2)0.8 at 5 and 300 K, respectively. This higher coercive field, upon cooling, indicates the presence of small superparamagnetic particles. The coercive field also increases with milling time, which is due to the reduced particle size and induced stain. The saturation magnetization decreases with increased milling time as a consequence of an increase in the superparamagnetic fraction and increased strain. Hard and soft magnetic properties are observed for y = 0.2 and y = 0.6 samples, respectively.

Alloys↗
PubMed2003

Antileishmanial drugs cause up-regulation of interferon-gamma receptor 1, not only in the monocytes of visceral leishmaniasis cases but also in cultured THP1 cells.

Apparently for the first time, the peripheral blood monocytes of individuals with active visceral leishmaniasis (VL) have been found to show reduced expression of interferon gamma receptor-1 (IFNGR1). Since interferon gamma is the main cytokine responsible for defence against leishmanial parasites, it was thought possible that effective antileishmanial drugs may up-regulate IFNGR1. Confocal microscopy confirmed that monocytes from VL patients who had been treated, with sodium antimony gluconate (SAG), did display IFNGR1 up-regulation. To see if this effect could be mimicked in vitro, IFNGR1 expression was investigated using a human macrophage cell line (THP1), northern blotting and confocal microscopy. When the THP1 cells were treated with SAG or pentamidine, their expression of the receptor was increased. This drug-induced up-regulation was more intense if the macrophages were infected with Leishmania donovani than if they were left uninfected. The possibility that at least some antileishmanial drugs act by up-regulating IFNGR1 expression needs to be explored further. A good model for investigating the mechanisms of action of antileishmanial drugs might be based on the THP1 cell line.

Acute Disease↗
PubMed2003

Evaluation & management of clinically labeled carcinoma head of the pancreas--a prospective study of 60 patients.

Carcinoma head of the pancreas are assessed by clinical examination, imaging, Endoscopic Retrograde Cholangio Pancreatography (ERCP), Fine Needle Aspiration Cytology (FNAC) and finally by laparotomy. Nevertheless still there is a dilemma in labeling these patients as having inoperable cancer pancreas because operable lesions may be wrongly labeled as inoperable or benign lesion may be thought to be malignant. The aim of this study is to evaluate these patients who present with clinical features of inoperable carcinoma of pancreas and to assess their status of inoperability. Efforts were taken to explore the possibilities of curative resection. If found inoperable, then tissue or cytological sampling of the lesion and the alternative palliation therapy offered to them. Palliative surgery and respective analysis of data was done in 60 patients with clinically labeled carcinoma head of the pancreas. Laparotomy was done for--(i) Assessment of inoperability, (ii) tissue or cytological sampling and (iii) Bilioenteric and gastro enteric bypass. The tumor was considered to be inoperable by peroperative assessment & trial dissection when it invaded the surrounding vital structure. Histological confirmation was made by intraoperative core needle biopsy; shave biopsy, biopsy of hepatic and lymph node metastasis. Cytological sampling was done by transduodenal and intralesional FNAC. Hepaticojejunostomy or Cholecystojejunostomy, Gastrojejunostomy and enteroenterostomy were performed as palliative procedure in all patients. Chemical splanchinectomy was performed in 25 patients. Twenty patients were diagnosed to have carcinoma by Endoscopic biopsy. In remaining 40 patients, peroperative tissue biopsy and cytological sampling yielded pancreatic carcinoma in 16 (40.0%), chronic pancreatitis in 6 (15.0%), pancreatic tuberculosis in 5 (12.5%), pancreatic non Hodgkin's lymphoma in 3 (7.5%) and metastatic pancreatic cancer in 2 (5.0%). However, it failed to reveal any definitive diagnosis in 8 (20.0%) patients. These interesting findings changed the preoperative diagnosis and guided us to plan the surgical procedure for cancerous and non-cancerous patients accordingly.

Aged↗
PubMed2002

Domain closure and action of uracil DNA glycosylase (UDG): structures of new crystal forms containing the Escherichia coli enzyme and a comparative study of the known structures involving UDG.

The structures of a new crystal form of free Escherichia coli uracil DNA glycosylase (UDG), containing four molecules in the asymmetric unit, and two forms of its complex with the proteinaceous inhibitor Ugi, containing two and four crystallographically independent complexes, have been determined. A comparison of these structures and the already known crystal structures containing UDG shows that the enzyme can be considered to be made up of two independently moving structural entities or domains. A detailed study of free and DNA-bound human enzyme strengthens this conclusion. The domains close upon binding to uracil-containing DNA, whereas they do not appear to do so upon binding to Ugi. The comparative study also shows that the mobility of the molecule involves the rigid-body movement of the domains superposed on flexibility within domains.

Crystallography, X-Ray↗
PubMed2002

Antibacterial activity of Terminalia pallida.

The methanol extract of the dried fruit powder of Terminalia pallida was evaluated for antimicrobial activity. The methanol extract showed a broad spectrum of antibacterial activity.

Anti-Bacterial Agents↗