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Biomedical subjects

A Roy

Publications and source records attributed to A Roy.

At least 37 records · Page 2Linked to original sources
PubMed2003

Association of deletion in the chromosomal 8p21.3-23 region with the development of invasive head & neck squamous cell carcinoma in Indian patients.

BACKGROUND & OBJECTIVES: Deletions in chromosome 8 (chr.8) have been shown to be necessary for the development of head and neck squamous cell carcinoma (HNSCC). Attempts have been made in this study to detect the minimal deleted region in chr.8 associated with the development of HNSCC in Indian patients and to study the association of clinicopathological features with the progression of the disease. METHODS: The deletion mapping of chr.8 was done in samples from 10 primary dysplastic lesions and 43 invasive squamous cell carcinomas from the head and neck region of Indian patients to detect allelic alterations (deletion or size alteration) using 12 highly polymorphic microsatellite markers. The association of the highly deleted region was correlated with the tumour node metastasis (TNM) stages, nodal involvement, tobacco habit and human papilloma virus (HPV) infection of the samples. RESULTS: High frequency (49%) of loss of heterozygosity (LOH) was seen within 13.12 megabase (Mb) region of chromosomal 8p21.3-23 region in the HNSCC samples, whereas the dysplastic samples did not show any allelic alterations in this region. The highest frequency (17%) of microsatellite size alterations (MA) was observed in the chr.8p22 region. The loss of short arm or normal copy of chr.8 and rare bi-allelic alterations were seen in the stage II-IV tumours (939, 5184, 2772, 1319 and 598) irrespective of their primary sites. The highly deleted region did not show any significant association with any of the clinical parameters. However, HPV infection was significantly associated (P < 0.05) with the differentiation grades and overall allelic alterations (LOH/MA) of the samples. INTERPRETATION & CONCLUSION: Our data indicate that the 13.12 Mb deleted region in the chromosomal 8p21.3-23 region could harbour candidate tumour suppressor gene(s) (TSGs) associated with the progression anti invasion of HNSCC tumours in Indian patients.

Alleles↗
PubMed2002

Design and development of an immunosensor for the detection of malaria in field conditions.

Eradication of malaria in Southeast Asian countries is still a distant goal, due to the absence of a simple, rapid and inexpensive diagnostic technique. Here, an immunosensor for the photometric detection of malaria, the malaria-detecting immunosensor (MDI), is developed to detect Plasmodium falciparum malarial antibodies in human blood. The method uses the principle of laser light-scattering by latex bead agglutinates in media monitored by a light-detecting device. Agglutination is induced by mixing antigen-coated latex beads with serum antibodies. Immunoreactions are measured in terms of the Tyndall effect in the transmitted beam detected by photodiodes. MDI sensitivity and specificity are compared with the results of enzyme-linked immunoabsorbent assay and laser light-scattering immunoassay techniques, which show that it is a good and sensitive monitoring device.

Agglutination Tests↗
PubMed2002

Mapping of the candidate tumor suppressor genes' loci on human chromosome 3 in head and neck squamous cell carcinoma of an Indian patient population.

The candidate tumor suppressor genes' (TSG) loci on human chromosome 3 (chr.3) were mapped in six dysplastic lesions and 51 primary squamous cell carcinoma from head and neck region of an Indian patient population by using 20 highly polymorphic microsatellite markers. The two chromosomal regions 3p12-13 and 3p21.2-22 have shown the highest losses of heterozygosity (LOHs) of 34.6-38% and 37-46%, respectively with statistically significant clinical correlation's with tobacco habit, positive lymph node and tumor stages. In addition, high frequencies of microsatellite size alterations (MAs) of 16.2-28.5% and 23.8-28.2% were observed in the chromosomal 3p11-13 and 3p21.2-22 regions, respectively, with significant above-mentioned clinical correlation only in the 3p11-13 region. In the dysplastic lesions, the prevalence of LOHs compared to the MAs had indicated that LOHs might be the early events. Five tumors at stage-III/IV seemed to have lost an entire normal copy of chr.3. It was of particular note that 17% (10/57) of the samples showed rare bi-allelic alterations mainly in and around the high LOHs regions. Thus, (1) the gradual increase of LOHs/MAs during progression of the tumor, (2) high frequencies of MAs, (3) rare bi-allelic alterations in and around high LOHs regions and (4) loss of wild type chr.3 in the later stages of tumor development have suggested that such alterations might provide selective growth advantage to the tumors. Also, we propose from our data that the high LOHs regions (3p12-13 and 3p21.2-22) could harbour putative TSG(s), responsible for the development of head and neck squamous cell carcinoma.

Adult↗
PubMed2002

Evaluation of the 3D BacT/ALERT automated culture system for the detection of microbial contamination of platelet concentrates.

Bacterial transmission remains the major component of morbidity and mortality associated with transfusion-transmitted infections. Platelet concentrates are the most common cause of bacterial transmission. The BacT/ALERT 3D automated blood culture system has the potential to screen platelet concentrates for the presence of bacteria. Evaluation of this system was performed by spiking day 2 apheresis platelet units with individual bacterial isolates at final concentrations of 10 and 100 colony-forming units (cfu) mL-1. Fifteen organisms were used which had been cited in platelet transmission and monitoring studies. BacT/ALERT times to detection were compared with thioglycollate broth cultures, and the performance of five types of BacT/ALERT culture bottles was evaluated. Sampling was performed immediately after the inoculation of the units, and 10 replicates were performed per organism concentration for each of the five types of BacT/ALERT bottles. The mean times for the detection of these 15 organisms by BacT/ALERT, with the exception of Propionibacterium acnes, ranged from 9.1 to 48.1 h (all 10 replicates were positive). In comparison, the time range found using thioglycollate was 12.0-32.3 h (all 10 replicates were positive). P. acnes' BacT/ALERT mean detection times ranged from 89.0 to 177.6 h compared with 75.6-86.4 h for the thioglycollate broth. BacT/ALERT, with the exception of P. acnes, which has dubious clinical significance, gave equivalent or shorter detection times when compared with the thioglycollate broth system. The BacT/ALERT system detected a range of organisms at levels of 10 and 100 cfu mL-1. This study validates the BacT/ALERT microbial detection system for screening platelets. Currently, the system is the only practically viable option available for routinely screening platelet concentrates to prevent bacterial transmission.

Aerobiosis↗
PubMed2001

Effects of voluntary ethanol intake on the expression of Ca(2+) /calmodulin-dependent protein kinase IV and on CREB expression and phosphorylation in the rat nucleus accumbens.

To define the molecular basis of alcohol drinking behaviors, the effects of voluntary ethanol intake on the expression of Ca(2+)/calmodulin-dependent protein kinase IV (CaM kinase IV) and on the expression and phosphorylation of cAMP responsive element binding protein (CREB) [corrected] in the nucleus accumbens (NAc), central amygdala, and frontal cortex of rats were investigated. Voluntary ethanol intake significantly decreased the expression of CaM kinase IV and CREB phosphorylation but not of CREB protein levels [corrected], specifically in the shell of NAc. These changes were not observed in the core of NAc, central amygdala and frontal cortex. Mianserin treatment significantly attenuated ethanol intake and antagonized the voluntary ethanol-induced reduction in expression of CaM kinase IV and CREB phosphorylation in the shell of NAc. This is the first evidence to suggest that decreased CaM kinase IV-dependent CREB phosphorylation in the shell region of NAc may play a role in the reward mechanisms of alcohol drinking.

Alcohol Drinking↗
PubMed2001

Distinguishability of Bell states.

More than two multipartite orthogonal states cannot always be discriminated if only local operations and classical communication (LOCC) are allowed. We show that four Bell states cannot be discriminated by LOCC, even probabilistically, using the separability properties of a four-party unlockable bound entangled state. Using an existing inequality among the measures of entanglement, we show that any three Bell states cannot be discriminated with certainty by LOCC. Exploiting the inequality, we calculate the distillable entanglement of a certain class of 4 multiply sign in circle 4 mixed states.

Journal Article↗
PubMed2001

Ryanodine receptor-mediated [Ca(2+)](i) release in glomus cells is independent of natural stimuli and does not participate in the chemosensory responses of the rat carotid body.

The hypothesis that intracellular calcium ([Ca(2+)](i)) release in glomus cells via ryanodine receptor (RyR) activation by caffeine may be independent of natural stimuli and chemosensory discharge was tested in the rat carotid body (CB). CB type I cells were isolated, plated and preloaded with calcium-sensitive fluorescent probe, Indo-1AM. With the increase of caffeine dose (0-50 mM) cytosolic calcium ([Ca(2+)](c)) increased from 85+/-15 nM to 1933+/-190 nM (n=6) at normoxia (PO(2)=125-130 Torr, PCO(2)=25-30 Torr, pH 7.30-7.35). Hypoxia (PO(2)=10-15 Torr) increased and hypocapnia (PCO(2)=7-9 Torr) decreased the cytoplasmic calcium [Ca(2+)](c) levels, independent of caffeine. Caffeine-related [Ca(2+)](c) increase was the same in the presence and the absence of extracellular calcium ([Ca(2+)](o)), indicating the source of Ca(2+) ions is the cellular store. Permeabilization of the cell membrane with saponin (25 microg/ml) retained the caffeine response. Additional treatment of the cells with 50 microM ryanodine (an inhibitor of the caffeine-activated RyR site) abolished caffeine-stimulated response. In vitro CB chemosensory (carotid sinus nerve, CSN) responses to hypoxia (PO(2)=35-40 Torr) were not altered by caffeine. These results suggest that [Ca(2+)](i) stores in CB cells, mobilized by RyR activation, do not participate in the CSN responses to natural stimuli.

Action Potentials↗
PubMed2001

Microsatellite instability in squamous cell carcinoma of head and neck from the Indian patient population.

Genomic instability in simple repeated sequences has been observed in several human cancers. We have analyzed 50 squamous cell carcinomas of the head and neck (SCCHN) and 5 pre-malignant severe dysplastic tissues from Indian patient populations for microsatellite instability in 18 different loci spread over eight different chromosomes. Among the tumors analyzed, 45% exhibited instability at two or more loci, and 15% exhibited instability at 40% of the markers tested. Similar analysis of SCCHN tumors from other populations (British, American and French) showed much less frequency of instability. SCCHN tumors in the present study did not show any instability in the mononucleotide repeat sequences. There is also a clear distinction in the nature of the instability in these tumors in comparison with colorectal tumors. These results suggest that the underlying mechanism generating this type of instability is different from those reported for colorectal tumors.

Adult↗
PubMed2001

Childhood trauma and hostility as an adult: relevance to suicidal behavior.

The objective of this study is to look for a relationship between childhood trauma and hostility as an adult. Toward this end, 294 recently abstinent cocaine or opiate dependent patients were asked to complete two questionnaires: the Childhood Trauma Questionnaire (CTQ) and the Hostility and Direction of Hostility Questionnaire (HDHQ). It was found that there were significant correlations between the HDHQ total hostility score and scores on the CTQ for childhood emotional abuse, physical abuse, sexual abuse, emotional neglect and physical neglect. Thus, these results suggest the possibility that childhood trauma may be a determinant of the personality dimension of hostility as an adult.

Adult↗
PubMed2001

Serum cholesterol, suicidal behavior and impulsivity in cocaine-dependent patients.

Relationships between serum cholesterol and suicidal behavior have been reported. As suicidal behavior is common in cocaine dependence, we looked for a relationship with serum cholesterol. To do this, we compared 57 cocaine-dependent patients who had attempted suicide with 111 cocaine-dependent patients who had never attempted suicide for their admission total serum cholesterol levels. We found that there were no significant differences between cocaine-dependent patients who had or had not attempted suicide in their total serum cholesterol levels. Also, there were no significant correlations between total serum cholesterol levels and scores on the Barratt Impulsivity Scale. Thus, admission total serum cholesterol does not appear to be clinically useful in the assessment of suicidal behavior in cocaine-dependent patients.

Adult↗
PubMed2001

Barium-stimulated chemosensory activity may not reflect inhibition of background voltage-insensitive K+ channels in the rat carotid body.

To test the hypothesis that the voltage-insensitive background leak K+ channel is responsible for the oxygen-sensitive properties of glomus cells in the rat carotid body (CB) we used Ba2+, a non-specific inhibitor of K+ currents. In vitro changes in cytosolic calcium ([Ca2+]c) and chemosensory discharge were studied to measure the effect of Ba2+. In normal Tyrode buffer, Ba2+ (3 and 5 mM) significantly increased carotid sinus nerve (CSN) discharge over baseline firing rates under normoxia (PO2 approximately 120 Torr) from approximately 150 to approximately 600 imp/0.5 s. However, addition of 200 microM Cd2+ which completely blocked increase in CSN activity stimulated by hypoxia (PO2 approximately 30 Torr), hypercapnia (PCO2 approximately 60 Torr, PO2 approximately 120 Torr) and high CO (PCO approximately 550 Torr, PO2 approximately 120 Torr) did not significantly inhibit Ba2+-stimulated CSN discharge. The response to hypoxia is abolished with Ca2+-free tyrode buffer containing 10 mM EGTA. Yet, in the same buffer, Ba2+ increased CSN discharge from approximately 2 to approximately 180 imp/0.5 s. With 200 microM Cd2+ and 10 mM EGTA, Ba2+ still increased CSN discharge from approximately 2 to approximately 150 imp/0.5 s. Oligomycin (2 microg) abolished the hypoxic response. However, in the presence of oligomycin CSN response to Ba2+ was significant. Since Ba2+ increased neural discharge under conditions where hypoxia stimulated CSN discharge is completely abolished, we suggest that the effect of Ba2+ on CSN discharge may not have anything to do with the oxygen sensing mechanism in the CB.

Animals↗
PubMed2001

An expedient route to 2,3-substituted and fused benzo[a]quinolizine-4-thione framework via ring annulation with beta-oxodithioesters.

[figure: see text] An efficient highly convergent route to hitherto unreported 2,3-substituted and annulated benzo[a]quinolizine-4-thiones 3 has been developed. The methodology involves ring annulation of 3,4-dihydro-6,7-dimethoxy-1-methylisoquinoline 1 with a variety of readily accessible acyclic and cyclic beta-oxodithioesters 2 in the presence of triethylamine in refluxing benzene. These benzo[a]quinolizine-4-thiones can be readily converted to the corresponding benzo[a]quinolizine-4-ones 5 via dethiomethylative hydrolysis of the respective benzo[a]quinolizinium salts 4 obtained by alkylation of 3 with methyl iodide.

Alkaloids↗
PubMed2001

Reduced glutathione, dithiothreitol and cytochrome P-450 inhibitors do not influence hypoxic chemosensory responses in the rat carotid body.

Glomus cells and carotid sinus afferents are anatomically connected, and the chemical events in the glomus cells are expected to be conveyed reflexly as afferent signals. Accordingly, K(+) channel inhibition of the glomus cell membrane is expected to be followed by excitation of the afferents. In order to test the redox inhibition of K(+) channels of glomus cells by reduced glutathione (GSH), dithiothreitol (DTT) and by cytochrome P-450 inhibitors (clotrimazole and miconazole), we measured the carotid sinus nerve (CSN) discharge using an in vitro perfused adult rat carotid body (CB) in the presence and absence of these chemicals which are expected to excite the afferents. Our findings were that these agents did not stimulate the CSN activities during normoxia and kept the hypoxic responses intact. These results led us to conclude that the redox modulation of glomus cells was not conveyed to the afferents, and this functional disconnection did not support the redox hypothesis of O(2) chemoreception in the whole carotid body.

Animals↗
PubMed2001

Depressive symptoms in African-American type 1 diabetics.

This study examined depressive symptoms and their correlates in African-American patients with type 1 diabetes. Five-hundred eighty-one diabetics participated in a study on risk factors for retinopathy in African-Americans with type 1 diabetes. Evaluations included structured interview, ocular examination, blood test, and completion of the Beck Depression Inventory (BDI). Among the 581 diabetic patients, 159 (26.9%) had a BDI score > 14. Significantly more of these patients were unemployed, had less education, lower socio-economic status, and less personal and family income than those who had a BDI < or = 14. Also, significantly more patients with a BDI score > 14 had proliferative retinopathy and were receiving disability payments. In the multiple logistic regression, two factors that significantly and independently associated with the BDI score > 14 were unemployment or not working due to disability. Both socio-economic and diabetic variables are associated with depressive symptoms among African-American patients with type 1 diabetes.

Adult↗
PubMed2001

Nucleic acid microarray technology for toxicology: promise and practicalities.

Much ongoing research in toxicology focuses on a hypothesis-driven mechanism of action approach aimed at understanding the molecular events mediating the actions of the chemicals of interest. Using this approach, investigators develop hypotheses based on observations, which may be derived from a host of resources but most frequently have been made within their own laboratories, or uncovered by others and reported in the scientific literature. Although the bulk of current understanding ofbiochemical toxicology emerged using studies based on observations derived in this way, this process, which is essentially based on existing information, may often limit the expansion knowledge. More simply expressed, one only finds that which one seeks. Without a clear understanding of the processes targeted by a specific toxin the problem of making observations that globally and accurately reflect the events mediating pathology which have been induced by the toxic agent is challenging. Recently, the development of high-throughput technologies for biochemical analysis of gene expression has led to innovative approaches in addressing the problem of making broad-based observations that more accurately reflect the entire spectrum of molecular lesions induced by specific toxins. These strategies include the use of new techniques in analysis of gene expression to convey information on alterations in mRNA levels, one of the earliest cellular signs initiated in response to a potential toxin. Prior to this time studies on toxicant-induced altered gene expression were limited to single, or small numbers of identified genes chosen by an investigator who reasoned, based on an existing observations, that levels of the proteins encoded by these genes were likely to be altered during toxic injury. Now, using cDNA or oligonucleotide genome-wide arrays, toxin-induced alterations in gene expression of thousands of genes can be examined simultaneously. Using these tools, molecular toxicologists can for the first time employ reasoned strategies to make observations, and then formulate hypotheses based on these observations.

Animals↗