Biomedical subjects

R Bandyopadhyay

Publications and source records attributed to R Bandyopadhyay.

At least 19 recordsLinked to original sources

PubMed2006

Microscopic dynamics of recovery in sheared depletion gels.

We report x-ray photon correlation spectroscopy and diffusing wave spectroscopy studies of depletion gels formed from nanoscale silica colloids in solutions of nonabsorbing polymer following the cessation of shear. The two techniques provide a quantitatively coherent picture of the dynamics as ballistic or convective motion of colloidal clusters whose internal motion is arrested. While the dynamics possesses features characteristic of nonergodic soft solids, including a relaxation time that grows linearly with the time since shear, comparison with behavior of quenched supercooled liquids indicates that this evolution is not directly related to traditional aging phenomena in glasses.

Journal Article↗

PubMed2006

Isolated massive thyroid metastasis in lung cancer.

Metastasis to the thyroid gland is rare despite its rich vascular supply. Among the pulmonary malignancies metastasising to the thyroid, adenocarcinomas are the commonest. The appearance of metastatic disease in lung carcinoma indicates a poor prognosis and the average survival is two months. We report a 62-year-old woman with squamous cell carcinoma of lung metastatic to the thyroid that produced massive enlargement of the gland. The appearance of the secondary preceded the diagnosis of the primary malignancy by a few months. Ultimately, the patient succumbed to her disease.

Carcinoma, Squamous Cell↗

PubMed2006

Correlation of lipid profile and carotid artery plaque as detected by Doppler ultrasound in ischaemic stroke patients--A hospital-based study.

Stroke is one of the leading causes of morbidity and mortality all over the world. Carotid plaque formation and intima media thickness can be a predictor of ischaemic stroke. In this regard studies from our country, are few and far between. This is a small hospital-based study to look in to this matter. We have assessed the intima media thickness of the common carotid as well as the internal and external carotid arteries by the ultrasound method. The lipid profiles were estimated and correlated with the intima media thickness. Results indicate that in the common as well as in the internal and external carotid arteries, the intima media thickness is a good predictor of ischaemic stroke. This thickness is also well correlated with the lipid levels in blood. Hence this non-invasive method can be used successfully to identify the high risk patients, prone to develop stroke.

Adult↗

PubMed2005

Risk factor analysis in ischaemic stroke: a hospital-based study.

Stroke represents a major health burden in our country. Ischaemic stroke has got several risk factors associated with increased chance of atherosclerosis. A small hospital-based study was done to look into the risk factors associated with ischaemic stroke. Forty patients with CT-confirmed cerebral infarction were taken for the study and detailed history and clinical findings were obtained. Investigations like complete haemogram, fasting blood glucose, urea, creatinine, lipid profile, serum Lp(a), homocysteine, fibrinogen, ECG, chest x-ray, echocardiography, MRI/MRA where indicated, were done to identify the risk factors as well. Results indicated that hypertension was the most prevalent (87.5%) risk factor followed by ischaemic heart disease (35%) and diabetes. Dyslipidaemia was also found in a significant number of cases, mostly elevated LDL, low HDL and elevated Lp(a). Fibrinogen and homocysteine were of less significance.

Adult↗

PubMed2004

Evolution of particle-scale dynamics in an aging clay suspension.

Multispeckle x-ray photon correlation spectroscopy was employed to characterize the slow dynamics of a suspension of highly charged, nanometer-sized disks. At wave vectors q corresponding to interparticle length scales, the dynamic structure factor follows a form f(q,t) approximately exp([-(t/tau)(beta)], where beta approximately 1.5. The relaxation time tau increases with the sample age t(a) approximately as tau approximately t(1.8)(a) and decreases with q as tau approximately q(-1). Such behavior is consistent with models that describe the dynamics in disordered elastic media in terms of strain from random, local structural rearrangements. The measured amplitude of f(q,t) varies with q in a manner that implies caged particle motion. The decrease in the range of this motion and an increase in suspension conductivity with increasing t(a) indicate a growth in interparticle repulsion as the mechanism for internal stress development implied by these models.

Aluminum Silicates↗

PubMed2004

Insulin in type 2 diabetes: promises to keep.

The concept which has evolved in the management of type 2 diabetes mellitus is early insulin therapy. In type 2 diabetes mellitus first phase insulin response is grossly impaired on eventually absent, overburdening phase 2 responses which obviously fail to compensate in the long run. Perpetuation of the age old practice to continue OHA while almost all beta-cells are exhausted is only buying time for starting insulin. Preservation of beta-cell function by early insulin therapy yields two important benefits: (1) Better glycaemic control at lower medication dose and (2) relative freedom from hypoglycaemia because of well preserved glucagon response. To ensure and to translate the proper action of insulin in the target organs we are now talking about designer insulins which are basically insulin analogues (short and long acting). So type 2 diabetes is a growing menace and is responsible for severe morbidity, mortality and poor quality of life. Good glycaemic control from the very beginning of diabetes has shown to favourably influence all of these and is accepted as a cardinal goal of proper diabetes care.

Diabetes Mellitus, Type 2↗

PubMed2004

Glycaemic consequences of HIV and highly active antiretroviral therapy: a pilot study and review of literature.

The metabolic consequences of HIV and AIDS are accentuated in the setting of highly active antiretroviral therapy. Peripheral lipodystrophy, central adiposity, hyperlipidaemia, insulin resistance and diabetes mellitus are frequent associations of protease inhibitor containing highly active antiretroviral therapy regimens. Ninety patients aged 25-50 years (males 52, females 38), seropositive for HIV 1 and 2 or both were selected to see the glycaemic profiles in asymptomatic early HIV disease with CD4 counts > 100/microl and to compare this with the glycaemic profile of (a) advanced HIV disease (CD4 counts < 200/microl), not on highly active antiretroviral therapy and (b) advanced HIV disease (CD4 counts < 200/microl), on uninterrupted non-protease inhibitor highly active antiretroviral therapy > 6 months. All the patients were grouped into 3: (1) Group A: CD4 counts > 500/microl (n=37), highly active antiretroviral therapy naive, (2) group B: CD4 counts < 200/microl (n=21), not on highly active antiretroviral therapy, and (3) group C: CD4 counts < 200/microl, receiving uninterrupted non-protease inhibitor based highly active antiretroviral therapy for > 6 months (n=32). The fasting blood glucose, glycosylated Hb (HbA1c) levels, were measured in all the patients in 3 groups and significance of difference between means was calculated among various groups. Body weight and waist-hip ratio were also measured. The results were analysed and compared with other studies.

Adult↗

PubMed2001

Short-chain fatty acid derivatives stimulate cell proliferation and induce STAT-5 activation.

Current chemotherapeutic and butyrate therapeutics that induce fetal hemoglobin expression generally also suppress erythropoiesis, limiting the production of cells containing fetal hemoglobin (F cells). Recently, selected short-chain fatty acid derivatives (SCFADs) were identified that induce endogenous gamma-globin expression in K562 cells and human burst-forming units-erythroid and that increase proliferation of human erythroid progenitors and a multilineage interleukin-3-dependent hematopoietic cell line. In this report, gamma-globin inducibility by these SCFADs was further demonstrated in mice transgenic for the locus control region and the entire beta-globin gene locus in a yeast artificial chromosome and in 2 globin promoter-reporter assays. Conditioned media experiments strongly suggest that their proliferative activity is a direct effect of the test compounds. Investigation of potential mechanisms of action of these SCFADs demonstrates that these compounds induce prolonged expression of the growth-promoting genes c-myb and c-myc. Both butyrate and specific growth-stimulatory SCFADs induced prolonged signal transducer and activator of transcription (STAT)-5 phosphorylation and activation, and c-cis expression, persisting for more than 120 minutes, whereas with IL-3 alone phosphorylation disappeared within minutes. In contrast to butyrate treatment, the growth-stimulating SCFADs did not result in bulk histone H4 hyperacetylation or induction of p21(Waf/Cip), which mediates the suppression of cellular growth by butyrate. These findings suggest that the absence of bulk histone hyperacetylation and p21 induction, but prolonged induction of cis, myb, myc, and STAT-5 activation, contribute to the cellular proliferation induced by selected SCFADs.

Animals↗

PubMed2001

A new autotuning algorithm for PID controllers using dead-beat format.

A novel algorithm for PID controllers based on dead-beat control and fuzzy inference mechanism is presented in this paper. The proposition is an extension of the work by the authors where the PI form of the algorithm was presented. The inclusion of the derivative term makes the method suitable for application in all types of processes including the ones having high rate disturbances. The proposed algorithm seems to be a complete and generalized PID autotuner as can be seen by the simulated and experimental results. In all the cases the method shows substantial improvement over the controller tuned with Ziegler Nichol's formula and the PI controller proposed in R. Bandyopadhyay, D. Patranabis, A fuzzy logic based PI autotuner, ISA Transactions 37 (1998) 227-235.

Journal Article↗

PubMed2001

Identification and characterization of satellite III subfamilies to the acrocentric chromosomes.

The centromeres and the short arms of the five pairs of acrocentric chromosomes in humans are composed of tandemly ordered repetitive DNA. Previous studies have suggested that the exchanges between acrocentric chromosomes have resulted in concerted evolution of different DNA sequences in their short arms. The acrocentric chromosomes are clinically relevant since they are involved in Robertsonian translocation formation and non-disjunction resulting in aneuploidy. Here we have identified seven new satellite III repetitive DNA subfamilies, determined their nucleotide sequences and established their chromosomal distributions on the short arms of the acrocentric chromosomes. Knowledge of these related sequences may help to elucidate the molecular basis of Robertsonian translocation formation.

Base Sequence↗

PubMed2001

Satellite III sequences on 14p and their relevance to Robertsonian translocation formation.

Robertsonian translocations (ROBs) are the most common rearrangements in humans, contributing significantly to genetic imbalance, fetal wastage, mental retardation and birth defects. Rob(14q21q) and rob(13q14q), which are formed predominantly during female meiosis, comprise the majority (approximately 85%) of all ROBs. Previous studies have shown that the breakpoints are consistently located within specific regions of the proximal short arms of chromosomes 13, 14, and 21. The high prevalence of these translocations, the consistent breakpoints found, and the fact that roughly 50% of cases occur sporadically suggest that the sequences at or near the breakpoints confer susceptibility to chromosome rearrangement and that the rearrangements occur through a specific mechanism. To investigate this hypothesis, we developed hamster-human somatic cell hybrids derived from de novo rob(14q21q) patients that contained the translocated chromosome segregated from the other acrocentric chromosomes. We determined the physical order of five satellite III subfamilies on 14p, and investigated their involvement in formation of these de novo translocations.

Abnormalities, Multiple↗

PubMed2001

Adrenal steroids act as inhibitory modulators of thyrofollicular cell morphology and proliferation in neonatal chicks (Gallus domesticus).

In the present study the effects of adrenal corticoids, both natural and synthetic, namely cortisol and dexamethasone respectively, was observed on the thyroid gland cell morphology and proliferation in neonatal male chicks (Gallus domesticus). Cortisol was injected at a dose of 4 mg/100 g body weight and dexamethasone at a dose of 1 mg/100 g b.w. subcutaneously daily for fifteen consecutive days. The control birds were similarly injected with normal saline at a daily dose of 0.2 ml per bird for the same time period. The results indicated that both cortisol and dexamethasone caused a significant decrease in thyrofollicular cell height. On the contrary, a significant increase in the ratio of the follicular diameter to the number of nuclei per follicle i.e. D/N value was observed in both cortisol and dexamethasone treated chicks. It was also observed that both cortisol and dexamethasone induced suppression of mitotic activity, as evidenced from a significant decrease in mitotic percentage compared with the control chicks. The present authors' studies thus indicate that adrenal corticoids act as inhibitory modulators of thyroid follicular activity as regards karyomorphology and cell proliferation.

Animals↗

PubMed2000

Observation of chaotic dynamics in dilute sheared aqueous solutions of CTAT.

The nonlinear flow behavior of a viscoelastic gel formed due to entangled, cylindrical micelles in aqueous solutions of the surfactant cetyl trimethylammonium tosilate (CTAT) has been studied. On subjecting the system to a step shear rate lying above a certain value, the shear and normal stresses show interesting time dependent behavior. The analysis of the measured time series shows the existence of a finite correlation dimension and a positive Lyapunov exponent, unambiguously implying that the dynamics can be described by that of a dynamical system with a strange attractor whose dimension increases with the increase in shear rate.

Journal Article↗

PubMed2000

Involvement of PL-D in the alternate signal tranduction pathway of macrophages induced by an external stimulus.

The alternate pathway of signal transduction via hydrolysis of phosphatidylcholine, the major cellular phospholipid, has been investigated in murine peritoneal macrophages. A sustained formation of diacylglycerol, is preceded by an enhanced production of phosphatidic acid, when the macrophages were given a stimulus with 12-O-tetradecanoyl phorbol-13-acetate for sixty minutes. Production of choline and choline metabolites are significantly increased too. Propranolol, which inhibits phosphatidate phosphohydrolase, the enzyme responsible for conversion of phosphatidic acid to diacylglycerol, can effectively block the formation of diacylglycerol. Inhibition of protein kinase C either by its inhibitors, staurosporine and H-7 or by depletion, apparently affect the generation of the lipid products. Moreover, based on the results of transphosphatidylation reaction, involvement of a phospholipase D in the phosphatidylcholine-hydrolytic pathway in macrophages is predicted. These observations support the view that probably the phorbol ester acting directly on protein kinase C of the macrophages activate their phosphatidylcholine-specific phospholipase D to allow a steady generation of second messengers, to enable them to participate in the cell signalling process in a more efficient manner than those generated in the phosphoinositide pathway of signal transduction.

Animals↗

PubMed2000

Influence of crystal habit on the surface free energy and interparticulate bonding of L-lysine monohydrochloride dihydrate.

The objective of the present study was to apply a technique to measure the surface energy of crystalline powders without changing the surface properties by compaction, and to relate such measurements to crystal habit and orientation. The surface free energy of uncompacted L-lysine monohydrochloride dihydrate (LH), determined using a modified sessile-drop method, reflected a combined value for the various faces, and was influenced by the relative size of the faces and the orientation of the crystals. The surface free energy values obtained from contact angle measurements were within the possible range calculated from the crystal structure. Discrepancies between the theoretical estimates of interparticulate cohesive strengths and those measured from the tensile strength of powder compacts were used to estimate the flaw sizes (or gaps between the particles) that act as stress concentrators and reduce the tensile strength of the compacts. The flaw sizes indicate packing and compressibility of the various crystal habits. In the absence of compressive load, compacts made out of the equidimensional crystals have the larger flaw sizes (wider cracks or wider gaps between the particles). At higher compaction pressures, the compacts from long rod-shaped crystals have longer crack lengths. The weakness of the compacts made from the long rods at the higher compaction pressures may be because of the longer crack length along the interparticulate boundary, which may result in a higher stress intensity at the crack tip and increased fracture propensity.

Chemistry, Pharmaceutical↗

PubMed1999

Contemporary global movement of emerging plant diseases.

Plant diseases are a significant constraint to agricultural productivity. Exotic plant diseases pose a continued threat to profitable agriculture in the United States. The extent of this threat has increased dramatically in the 1980s and 1990s due to the expansion of international trade in agricultural products and frequent movement of massive volume of people and goods across national boundaries. Introduction of new diseases has not only caused farm losses, but has also diminished export revenue since phytosanitary issues are linked to international commerce. Plant pathogens and their vectors have also moved across national boundaries, sometimes naturally and at other times influenced by the recent changes in trade practices. Sorghum ergot, Karnal bunt of wheat, potato late blight, and citrus tristeza are some of the most recent examples of enhanced importance of diseases due to the introduction of plant pathogens or vectors.

Agriculture↗

PubMed1996

Neither the homeodomain nor the activation domain of Bicoid is specifically required for its down-regulation by the Torso receptor tyrosine kinase cascade.

Bicoid (Bcd) is a maternal morphogen responsible for patterning the head and thorax of the Drosophila embryo. Correct specification of head structure, however, requires the activity of the Torso receptor tyrosine kinase cascade, which also represses expression of Bcd targets at the most anterior tip of the embryo. Here, we investigate the role of both the homeodomain (HD) and the activation domain of Bcd in the anterior repression of its targets. When a Bcd mutant protein whose HD has been replaced by the Gal4 DNA-binding domain is expressed in early embryos, a reporter gene driven by Gal4 DNA-binding sites is first activated in an anterior domain and then repressed from the anterior pole. The down-regulation of Bcd-Gal4 activity requires torso function but does not depend on endogenous bcd activity, indicating that the Bcd protein alone and none of its targets is required to mediate the effect of torso. Functional analysis of a chimeric protein, whose activation domain has been replaced by a generic activation domain, indicates that the activation domain of Bcd is also not specifically required for its down-regulation by Torso. We propose that Torso does not affect the ability of Bcd to bind DNA, but instead directs modification of Bcd or of a potential Bcd co-factor, which renders the Bcd protein unable to activate transcription.

Animals↗

PubMed1995

Camping with a friend. Helping adolescents cope with diabetes.

The Florida Camp for Children and Youth With Diabetes sponsored a weekend in which teenagers with diabetes invited a friend of the same sex without diabetes to participate in a two-day retreat. This program was designed to encourage friends to take an active role in motivating the teen with diabetes to perform his or her diabetes-related tasks in a responsible manner. Forty-six patients ranging in age from 12-17 years brought friends. Those with diabetes participated in rap sessions as well as educational sessions attempting to teach independence in self-care. The friends were taught the basics of diabetes as well as given an opportunity to inject saline and monitor their own blood glucose levels. A choice of activities was interspersed with education.

Adaptation, Psychological↗