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Biomedical subjects

D Chowdhury

Publications and source records attributed to D Chowdhury.

At least 37 records · Page 2Linked to original sources
PubMed1995

Synaptotagmin I and 1B4 are identical: implications for synaptotagmin distribution in the primate brain.

We have determined that the human cDNA sequence of the previously described primate brain mRNA species 1B4 is nearly identical (99.95% similarity) to that of human Synaptotagmin I. The apparent identity of Synaptotagmin I with 1B4, whose distribution in the brain of the monkey Cynomolgous was determined previously by Northern blot and in situ hybridization (ISH) analyses, reveals the Synaptotagmin I is differentially expressed in the primate brain. Primate Synaptotagmin I mRNA is enriched in hindbrain structures relative to forebrain structures by Northern blot analysis. By ISH analysis, primate Synaptotagmin I mRNA is highly expressed in occipital cortex and lateral geniculate (visual system components) and differentially expressed across topographic cortical boundaries between inferior and superior temporal gyrus (a polymodal zone with visual, auditory and somatosensory inputs) and between areas 17 and 18 of the visual cortex (primary and secondary visual areas). Cortical expression is also enriched in layers V and VI, which contain large pyramidal projection neurons. Synaptotagmin I's greater association with large projection neurons and with some components of visual sensory transduction could reflect a requirement of these neural components for greater synaptic activity. Synaptotagmin I expression in the primate brain is also dissimilar to Synaptotagmin I expression in rodents. Thus, variation of Synaptotagmin I expression has occurred during mammalian evolution, perhaps as a consequence of the larger size and neurotransmitter requirements of primate neurons.

Base Sequence↗
PubMed1995

The role of bronchodilators in the management of bronchiolitis: a clinical trial.

A randomized clinical trial was conducted on young children with bronchiolitis admitted to hospital with moderate illness to determine the efficacy of the bronchodilators Salbutamol and ipratropium bromide, either as a single drug or in combination, given as a nebulized solution, compared with a normal saline placebo. Eighty-nine patients, aged from 23 days to 11 months, were randomized into four groups, depending on administered drug or placebo, as follows: group 1--Salbutamol (n = 20); group 2--ipratropium bromide (n = 23); group 3--combined Salbutamol and Ipratropium bromide (n = 24); group 4--normal saline (n = 22). The groups were identical with respect to age, sex, family history of atopy, respiratory syncytial virus (RSV) positivity and enrollment score. They were scored using the clinical parameters of wheezing, retractions and respiratory rate at enrollment, at 30 and 60 minutes after the first nebulization, and after 60 minutes following completion of subsequent nebulization at 6, 12, 24 and 36 hours. We did not find any significant difference in the rate of improvement and the final score (p = 0.49) in the four groups. The same finding was also noted in children aged more than 3 months (p = 0.35) and in those positive for RSV infection (p = 0.18). The lengths of hospitalization in the four groups were also similar (p = 0.79). It is concluded that there is no role for the nebulized bronchodilators Salbutamol and Ipratropium bromide, either as a single agent or in combination, compared with normal saline placebo in treating young children in hospital with bronchiolitis.

Administration, Inhalation↗
PubMed1993

A unified model of immune response. II: Continuum approach.

In an earlier paper in this journal (1990, J. theor. Biol. 145, 207-215) we developed a unified model for normal immune response, autoimmune response and AIDS, where the concentration of each type of cell involved in the immune response is represented by a discrete automaton and the population dynamics of the relevant cells are formulated in terms of dynamical maps in discrete time. In this paper we study the continuum version of this unified model where the cell concentrations are represented by real variables whose evolution with continuous time is described by differential equations. We discuss possible ways to extend this model incorporating new experimental results and to generalize it along the new emerging trends in network theories of immune response. Our work also illustrates some of the relative advantages and disadvantages of the discrete and continuum formulations of the models of immune response.

Autoimmunity↗
PubMed1991

A discrete model for immune surveillance, tumor immunity and cancer.

In this paper we propose a model of tumor immunity in terms of discrete automata where each automation describes the concentration of one particular type of cell involved in immune response. In contrast to the earlier models of normal immune response, there is more than one type of cell surface antigen in this model. As a consequence, the tumor can evade destruction through humoral response by changing its identity. However, the tumor can be killed by the killer cells through cell-mediated response unless protected by a high concentration of the suppressor T cells.

Computer Simulation↗
PubMed1990

A unified discrete model of immune response.

In this paper we propose a unified model of immune response in terms of discrete automata describing the concentrations of the cells constituting the immune network. The model of normal immune response proposed by Kaufman, Urbain and Thomas and that of auto-immune response proposed by Weisbuch, Atlan and Cohen are special cases of this unified model. Moreover, this model also describes the immune response in patients infected by the human immunodeficiency virus (HIV), the virus that is known to cause Acquired Immune Deficiency Syndrome (AIDS).

Antibody Formation↗
PubMed1989

Antifertility effect of Piper betle Linn. extract on ovary and testis of albino rats.

Chronic administration (sc) of the extract of the stalk of P. betle at 30 mg/kg body weight daily for 21 days produced significant decrease in oestrogen and androgen dependent target organ weights along with increase in cholesterol in adrenal, ovary and testis. Acid and alkaline phosphatase activities in serum, liver and kidney did not exhibit any toxic effect. There was marked change in morphology of testis and ovary. Vaginal smear showed prolonged dioestrus in treated female. The treated male showed decreased number and motility of sperm. Both male and female remained infertile after treatment suggesting antifertility activity of the extract on both sexes of albino rats.

Animals↗