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Biomedical subjects

C Dutta

Publications and source records attributed to C Dutta.

At least 19 recordsLinked to original sources
PubMed2006

Studies on commuters' exposure to BTEX in passenger cars in Kolkata, India.

Commuters' exposure to volatile organic compounds (VOCs) especially BTEX travelling in passenger cars in Kolkata, India were quantified in Phase I (2001-2002) and Phase II (2003-2004). Monitoring was made inside and in the immediate outside of passenger cars fitted with and without catalytic converters using different types of fuels, along two congested urban routes. During Phase I of the study, the benzene content in gasoline was 5% and the mean concentration of in-vehicle benzene in cars without catalytic converter was found to be as high as 721.2 microg/m3. In Phase II when the benzene content was reduced to <3% and with modified engine type, the mean in-vehicle benzene concentration was reduced to 112.4 microg/m3. The in-vehicle concentration varied with engine type and age of the vehicle. Roadside ambient mean concentration of benzene was 214.8 microg/m3 and 30.8 microg/m3 in Phase I and Phase II respectively.

Air Pollutants↗
PubMed2002

The differential role of spinal MHC class II and cellular adhesion molecules in peripheral inflammatory versus neuropathic pain in rodents.

The present study was designed to determine the role of central expression of immunoregulatory molecules in the development and maintenance of allodynia following a peripheral inflammatory insult or nerve transection. Differential spinal expression of major histocompatibility complex (MHC) class II, platelet-endothelial cellular adhesion molecule (PECAM), intercellular adhesion molecule (ICAM) and CD4 was observed in the two injury models. Intraplantar zymosan produced transient allodynia and only PECAM and ICAM immunoreactivity. In contrast, persistent mechanical allodynia and enhanced spinal PECAM, ICAM, MHC class II and CD4 immunoreactivity was observed following peripheral nerve transection. MHC class II knockout mice exhibited attenuated allodynia following spinal nerve transection as compared to wild-type control mice. These findings suggest that central neuroimmune activation may contribute to the maintenance of neuropathic pain following peripheral L5 spinal nerve transection but not following a peripheral inflammatory insult.

Animals↗
PubMed2000

Attachment of Toxoplasma gondii to a specific membrane fraction of CHO cells.

We have observed previously that attachment of Toxoplasma gondii to synchronized host cells is considerably increased at the mid-S phase (4 h postrelease). Synchronized CHO host cells at the mid-S phase were fractionated by molecular weight, and the antigens were used to produce a panel of polyclonal mouse antisera. The polyclonal antisera raised against fraction 4 with molecular mass ranging approximately from 18 to 40 kDa significantly reduced attachment to mid-S-phase host cells. Immunofluorescence assays demonstrated strong reactivity to mid-S-phase host cells and identified a number of potential receptors on Western blots. These data indicate that there is a specific host membrane receptor for parasite attachment that is upregulated during the mid-S phase of the host cell cycle.

Animals↗
PubMed1999

Kinetic asymmetry as a key source of functional diversity in biochemical networks.

From the analysis of the dynamic properties of various symmetric and asymmetric kinetic schemes, the present report demonstrates that all kinetic schemes, which can be hypothetically divided into two equal halves about an axis of mirror symmetry, are endowed with structural metastability under mass-closed conditions. In mass-closed symmetric schemes, absolute symmetry in reaction conditions in two halves is essential for the occurrence of ordered dynamic behaviour. Even an infinitesimal deviation from the symmetry relations instantaneously drives such systems from limit-cycles to turbulence. Reaction schemes with no axes of symmetry may exhibit a large variety of complex, structurally stable temporal order for wide ranges of values of system parameters and variables. Kinetic asymmetry, therefore, may confer to biochemical networks the functional diversity as well as stability against environmental perturbations.

Journal Article↗
PubMed1998

Codon usage in highly expressed genes of Haemophillus influenzae and Mycobacterium tuberculosis: translational selection versus mutational bias.

Biases in the codon usage and base compositions at three codon sites in different genes of A+T-rich Gram-negative bacterium Haemophillus influenzae and G+C-rich Gram-positive bacterium Mycobacterium tuberculosis have been examined to address the following questions: (1) whether the synonymous codon usage in organisms having highly skewed base compositions is totally dictated by the mutational bias as reported previously (Sharp, P.M., Devine, K.M., 1989. Codon usage and gene expression level in Dictyostelium discoideum: highly expressed genes do 'prefer' optimal codons. Nucleic Acids Res. 17, 5029-5039), or is also controlled by translational selection; (2) whether preference of G in the first codon positions by highly expressed genes, as reported in Escherichia coli (Gutierrez, G., Marquez, L., Marin, A., 1996. Preference for guanosine at first codon position in highly expressed Escherichia coli genes. A relationship with translational efficiency. Nucleic Acids Res. 24, 2525-2527), is true in other bacteria; and (3) whether the usage of bases in three codon positions is species-specific. Result presented here show that even in organisms with high mutational bias, translational selection plays an important role in dictating the synonymous codon usage, though the set of optimal codons is chosen in accordance with the mutational pressure. The frequencies of G-starting codons are positively correlated to the level of expression of genes, as estimated by their Codon Adaptation Index (CAI) values, in M. tuberculosis as well as in H. influenzae in spite of having an A+T-rich genome. The present study on the codon preferences of two organisms with oppositely skewed base compositions thus suggests that the preference of G-starting codons by highly expressed genes might be a general feature of bacteria, irrespective of their overall G+C contents. The ranges of variations in the frequencies of individual bases at the first and second codon positions of genes of both H. influenzae and M. tuberculosis are similar to those of E. coli, implying that though the composition of all three codon positions is governed by a selection-mutation balance, the mutational pressure has little influence in the choice of bases at the first two codon positions, even in organisms with highly biased base compositions.

Animals↗
PubMed1997

Complex dynamics of mass-closed coupled autocatalytic systems in response to minute asymmetric perturbations.

The role of kinetic coupling in catering to a remote-control mechanism for the onset and regulation of self-organization phenomena in a multicompartmental biochemical system has been examined. Using two cyclic autocatalytic reaction networks operating in two chambers separated by a membrane and coupled through a common cofactor, it has been demonstrated that (i) in response to asymmetric perturbations, the coupled reaction networks exhibit a variety of temporal self-organization phenomena such as bistability, multiple periodicity, hard excitation and coexistence of aperiodic oscillation with limit cycle even in mass-closed conditions; (ii) without disturbing a network directly, its dynamic behaviour can be regulated by perturbing some other network kinetically coupled to it and (iii) the dynamics of two coupled networks can be made to flip-flop between oscillatory and steady-states simply by modulating the time of application of external perturbations. The extreme sensitivity of this model to minute asymmetric fluctuations in the environment can predict how the impact of local changes in physico-chemical conditions can be transmitted from one compartment to another through coupled biochemical pathways in a living cell.

Journal Article↗
PubMed1997

Chaos game representation of proteins.

The present report proposes a new method for the chaos game representation (CGR) of different families of proteins. Using concatenated amino acid sequences of proteins belonging to a particular family and a 12-sided regular polygon, each vertex of which represents a group of amino acid residues leading to conservative substitutions, the method can generate the CGR of the family and allows pictorial representation of the pattern characterizing the family. An estimation of the percentages of points plotted in different segments of the CGR (grid points) allows quantification of the nonrandomness of the CGR patterns generated. The CGRs of different protein families exhibited distinct visually identifiable patterns. This implies that different functional classes of proteins follow specific statistical biases in the distribution of different mono-, di-, tri-, or higher order peptides along their primary sequences. The potential of grid counts as the discriminative and diagnostic signature of a family of proteins is discussed.

Algorithms↗
PubMed1997

Significance of sarcopenia in the elderly.

At the present time, there is only limited understanding of the public health significance of sarcopenia. The well-recognized functional consequences of sarcopenia include gait and balance problems and increased risk for fall. Ultimately, these impairments can lead to the loss of physical functional independence. However, sarcopenia may also contribute to an increased risk for chronic diseases such as diabetes and osteoporosis. Future studies of the pathophysiologic significance of sarcopenia need to consider the contribution(s) of muscle properties (e.g., muscle fiber composition, muscle blood flow, fatigue characteristics, innervation) to alterations in physical performance, metabolism and physiology, and skeletal health. More comprehensive studies on the sequelae of sarcopenia are critical to an accurate assessment of the public health burden that sarcopenia poses to the elderly population.

Aged↗
PubMed1995

The significance of sarcopenia in old age.

Our knowledge of the significance of sarcopenia in old age is limited by a lack of epidemiologic data, an incomplete assessment of the pathophysiologic consequences of age-related decrements in muscle mass and quality, and poor understanding of the underlying mechanisms responsible for these decrements. These gaps prevent us from fully appreciating the extent of the public health burden that sarcopenia poses, and present major obstacles to the elucidation of therapies to prevent or reverse sarcopenia in the elderly. The National Institute on Aging convened the Workshop on Sarcopenia to address these issues. The primary questions explored at the workshop included: (a) What research is needed to determine the clinical and functional significance of sarcopenia? (b) What research is needed to understand its etiology? and (c) What opportunities are there for determining the efficacy of current or potential interventions to prevent or retard the development of sarcopenia? The research recommendations from the workshop underscored the need for more dialogue between researchers in different fields (e.g., endocrinology, exercise physiology, bone biology) and for multidisciplinary approaches in order to gain greater insight into sarcopenia. The summary of the research directions which follows has been organized according to the primary questions of the workshop.

Aged↗
PubMed1992

Mathematical characterization of Chaos Game Representation. New algorithms for nucleotide sequence analysis.

Chaos Game Representation (CGR) can recognize patterns in the nucleotide sequences, obtained from databases, of a class of genes using the techniques of fractal structures and by considering DNA sequences as strings composed of four units, G, A, T and C. Such recognition of patterns relies only on visual identification and no mathematical characterization of CGR is known. The present report describes two algorithms that can predict the presence or absence of a stretch of nucleotides in any gene family. The first algorithm can be used to generate DNA sequences represented by any point in the CGR. The second algorithm can simulate known CGR patterns for different gene families by setting the probabilities of occurrence of different di- or trinucleotides by a trial and error process using some guidelines and approximate rules-of-thumb. The validity of the second algorithm has been tested by simulating sequences that can mimic the CGRs of vertebrate non-oncogenes, proto-oncogenes and oncogenes. These algorithms can provide a mathematical basis of the CGR patterns obtained using nucleotide sequences from databases.

Algorithms↗
PubMed1992

The cellular and molecular regulation of 1,25(OH)2D3 production.

The synthesis of 1,25(OH)2D3 is a critical control point in the regulation of calcium metabolism, and possibly in the growth and differentiation of a number of cell types. This paper reviews our current understanding of the regulation of this process at the cellular and molecular levels, with the emphasis on the mechanisms of feedback control 1,25(OH)2D3 itself, control of parathyroid hormone, the roles of cyclic AMP dependent protein kinase and protein kinase C, and the interaction between the various intracellular regulators of 1,25(OH)2D3 production.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1990

Detection of hemoprotein peroxidase activity on polyvinylidene difluoride membrane.

The feasibility of detecting hemoproteins after electroblotting was examined. Hemoproteins were subjected to lithium dodecyl sulfate-polyacrylamide gel electrophoresis (LDS-PAGE) and then electroblotted and peroxidase activity was detected with 3,3',5,5'-tetramethylbenzidine The sensitivity and specificity of tetramethylbenzidine staining of LDS-PAGE gels was retained when proteins were electroblotted. Subsequent staining of the membrane with Coomassie blue R-250 revealed a protein pattern similar to that in the polyacrylamide gel. Thus electroblotting of hemoproteins does not affect resolution of the electrophoretic pattern and heme-associated peroxidase activity. Additionally, the ability to stain hemoproteins on polyvinylidene difluoride membranes offers the advantage of utilizing the same membrane for further biochemical and immunological characterizations.

Animals↗
PubMed1989

In vitro effect of lorazepam on Mg2+ and (Na+,K+) ATPases of human foetal brain.

Lorazepam (LZ), a benzodiazepine group of drug, inhibits Mg2+ and (Na+,K+) ATPases (EC 3.6.1.3) activity of human foetal and adult brain. The inhibitory effect neither varied with respect to the region (i.e. cerebrum and cerebellum) nor with the age of the foetus. The inhibition of ATPases activity indicates that the neuronal transmission processes, may be affected and raises the possibility of developmental disturbances.

Brain↗