Complex methylene-blue-sensitized polyvinyl chloride: a polymer matrix for hologram recording

A new polymer matrix sensitized with methylene blue for use as an optical recording material is described here. The characterization is done to determine the optimal recording conditions. These films need no chemical development and are found to be stable for several months. The matrix has excellent shelf life and needs an exposure only as short as 20 s. Direct imaging was done on this material.

Optimization of pH and direct imaging conditions of complexed methylene blue sensitized poly(vinyl chloride) films

Significant results of our experimental investigations on the dependence of pH on real time transmission characteristics on recording media fabricated by doping PVC with complexed methylene blue are presented. The optimum pH value for faster bleaching was found to be 4 . 5. In typical applications, the illumination from one side, normal to the surface of this material, initiates a chemical sequence that records the incident light pattern in the polymer. Thus direct imaging can be successfully done on this sample. The recorded letters were very legible with good contrast and no scattering centres. Diffraction efficiency measurements were also carried out on this material.

MUSCARINIC M1 AND M3 RECEPTOR GENE EXPRESSION DURING PANCREATIC REGENERATION AND INSULIN SECRETION IN RATS

The present work is an attempt to understand the role of acetylcholine muscarinic M1 and M3 receptors during pancreatic regeneration and insulin secretion. The work focuses on the changes in the muscarinic M1 and M3 receptors in brain and pancreas during pancreatic regeneration. The effect of these receptor subtypes on insulin secretion and pancreatic P-cell proliferation were studied in vitro using rat primary pancreatic islet culture. Muscarinic Ml and M3 receptor kinetics and gene expression studies during pancreatic regeneration and insulin secretion will help to elucidate the role of acetylcholine functional regulation of pancreatic u-cell proliferation and insulin secretion.The cholinergic system through muscarinic M1 and M3 receptors play an important role in the regulation of pancreatic (3-cell proliferation and insulin secretion . Cholinergic activity as indicated by acetylcholine esterase, a marker for cholinergic system, decreased in the brain regions - hypothalamus, brain stem, corpus striatum, cerebral cortex and cerebellum during pancreatic regeneration. Pancreatic muscarinic M1 and M3 receptor activity increased during proliferation indicating that both receptors are stimulatory to (3-cell division. Acetylcholine dose dependently increase EGF induced DNA synthesis in pancreatic islets in vitro, which is inhibited by muscarinic antagonist atropine confirming the role of muscarinic receptors. Muscarinic M1 and M3 receptor antagonists also block acetycholine induced DNA synthesis suggesting the importance of these receptors in regeneration. Acetylcholine also stimulated glucose induced insulin secretion in vitro which is inhibited by muscarinic M1 and M3 receptor antagonists. The muscarinic receptors activity and their functional balance in the brain and pancreas exert a profound influence in the insulin secretion and also regeneration of pancreas

Dopamine Receptor Gene Expression In Streptozotocin Induced Diabetic Rats And Its Role In Insulin Secretion

Diabetes Mellitus is a metabolic disorder associated with insulin deficiency, which not.only affects the carbohydrate metabolism but also is associated with various central and peripheral complications. Chronic hyperglycemia during diabetes mellitus is a major initiator of diabetic microvascular complications like retinopathy, neuropathy, The central nervous system (CNS) neurotransmitters play an important role in the regulation of glucose homeostasis. These neurotransmitters mediate rapid intracellular communications not only within the central nervous system but also in the peripheral tissues. They exert their function through receptors present in both neuronal and non neuronal cell surface that trigger second messenger signaling pathways. Dopamine is a neurotransmitter that has been implicated in various central neuronal degenerative disorders like Parkinson's disease and behavioral diseases like Schizophrenia. Dopamine is synthesised from tyrosine, stored in vesicles in axon terminals and released when the neuron is depolarised. Dopamine interacts with specific membrane receptors to produce its effect. Dopamine plays an important role both centrally and peripherally. The recent identification of five dopamine receptor subtypes provides a basis for understanding dopamine's central and peripheral actions . Dopamine receptors are classified into two major groups : DA D1 like and DA D2 like. Dopamine D1 like receptors consists of DA D1 and DA D5 receptors . Dopamine D2 like receptors consists of DA D2, DA D3 and DA D4 receptors. Stimulation of the DA D1 receptor gives rise to increased production of cAMP. Dopamine D2 receptors inhibit cAMP production, but activate the inositol phosphate second messenger system . Impairment of central dopamine neurotransmission causes muscle rigidity, hormonal regulation , thought disorder and cocaine addiction. Peripheral dopamine receptors mediate changes in blood flow, glomerular filtration rate, sodium excretion and catecholamine release. The dopamine D2 receptors increased in the corpus striatum and cerebral cortex but decreased in the hypothalamus and brain stem indicating their involvement in regulating insulin secretion. Dopamine D2 receptor which has a stimulatory effecton insulin secretion decreased in the pancreatic islets during diabetes. Our in vitro studies confirmed the stimulatory role of dopamine D2 receptors in stimulation of glucose induced insulin secretion. A detailed study at the molecular level on the mechanisms involved in the role of dopamine in insulin secretion, its functional modification could lead to therapeutic interventions that will have immense clinical importance.

A Chloride Ion-Selective Potentiometric Sensor Based on a Polymeric Schiff Base Complex

This paper describes the fabrication of an ion-selective electrode in which a polymeric Schiff base complex of cobalt(II) is used as the ionophore.The main advantage of the electrode is that it is mechanically stable upto 3 months..The electrode shows a linear response in the range of 2.5 × 10-5-0.5 × 10-1 mol dm-3. The response time of the electrode is 30 s.The pH range at which the electrode works is 3.8 to 6.8. The electrode was found to be selective towards chloride ion in the presence of ions like Na+, Ca2+, Mn2+, ,Fe3+, Co2+, Ni2+, Cu2+, Zn2+, CH3COO-, NO3-, SO42- ,Br- and NO2-.

Studies on Metallocene Polyolefin and Polyvinyl Chloride for Blood and Blood Component Storage Applications

Plasticized poly(vinyl chloride) (pPVC), although a major player in the medical field, is at present facing lot of criticism due to some of its limitations like the leaching out of the toxic plasticizer, di ethylhexyl phthalate (DEHP) to the medium and the emission of an environmental pollutant,dioxin gas,at the time of the post use disposal of PVC Products by incineration. Due to these reasons, efforts are on to reduce the use of pPVC considerably in the medical field and to find viable alternative materials. The present study has been undertaken in this context to find a suitable material for the manufacture of medical aids in place of pPVC. The main focus of this study has been to find out a non-DEHP material as plasticizer for pPVC and another suitable material for the complete repalcement of pPVC for blood/ blood component storage applications.Two approaches have been undertaken for this purpose-(1)the controversial plasticizer, DEHP has been partially replaced by polymeric plasticizers(2) an alternative material, namely, metallocene polyolefin (mPO) has been used and suitably modified to match the properties of flexible PVC used for blood and blood component storage applications.

Second Order Fit for Mercuric Chloride Catalysed Solvolysis of Alkyl Chlorides in Aqueous DMSO Solvents

Kinetics of mercuric chloride catalysed solvolysis of l-butyl chloride, benzyl chloride. p-methylbenzyl chloride, l-phenylethyl chloride and triethylcarbinyl chloride have been studied in aq. DMSO, aq. acetonitrile and aq. ethanol. The kinetic data fit a second order rate equation in aq. DMSO. The calculated values of the second order rate coefficients increase in the case of aq. acetonitrile and aq. ethanol. The order in catalyst in 95%(v/v) aq. DMSO is less than unity.

Mercuric Chloride Catalysed Solvolysis of Benzyl Chloride in Water & Highly Aqueous Organic Solvent Systems

Kinetics of mercuric chloride catalysed solvolysis of benzyl chloride have been studied in water. 10% aq. ethanol, 10,20 and 30% aq. acetone and 20% aq. DMSO. The results confirm the operation of a mass law effect.

GABAA and GABAB Receptor Gene Expression and Functional Regulation During Pancreatic Regeneration and Insulin Secretion in Rats

The present study demonstrate the functional alterations of the GABAA and GABAB receptors and the gene expression during the regeneration of pancreas following partial pancreatectomy. The role of these receptors in insulin secretion and pancreatic DNA synthesis using the specific agonists and antagonists also are studied in vitro. The alterations of GABAA and GABAR receptor function and gene expression in the brain stem, crebellum and hypothalamus play an important role in the sympathetic regulation of insulin secretion during pancreatic regeneration. Previous studies have given much information linking functional interaction between GABA and the peripheral nervous system. The involvement of specific receptor subtypes functional regulation during pancreatic regeneration has not given emphasis and research in this area seems to be scarce. We have observed a decreased GABA content, down regulation of GABAA receptors and an up regulation of GABAB receptors in the cerebral cortex, brain stem and hypothalamus. Real Time-PCR analysis confirmed the receptor data in the brain regions. These alterations in the GABAA and GABAB receptors of the brain are suggested to govern the regenerative response and growth regulation of the pancreas through sympathetic innervation. In addition, receptor binding studies and Real Time-PCR analysis revealed that during pancreatic regeneration GABAA receptors were down regulated and GABAB receptors were up regulated in pancreatic islets. This suggests an inhibitory role for GABAA receptors in islet cell proliferation i.e., the down regulation of this receptor facilitates proliferation. Insulin secretion study during 1 hour showed GABA has inhibited the insulin secretion in a dose dependent manner in normal and hyperglycaemic conditions. Bicuculline did not antagonize this effect. GABAA agonist, muscimol inhibited glucose stimulated insulin secretion from pancreatic islets except in the lowest concentration of 1O-9M in presence of 4mM glucose.Musclmol enhanced insulin secretion at 10-7 and 10-4M muscimol in presence of 20mM glucose- 4mM glucose represents normal and 20mM represent hyperglycaemic conditions. GABAB agonist, baclofen also inhibited glucose induced insulin secretion and enhanced at the concentration of 1O-5M at 4mM glucose and at 10-9M baclofen in presence of 20mM glucose. This shows a differential control of the GABAA and GABAB receptors over insulin release from the pancreatic islets. During 24 hours in vitro insulin secretion study it showed that low concentration of GABA has inhibited glucose stimulated insulin secretion from pancreatic islets. Muscimol, the GABAA agonist, inhibited the insulin secretion but, gave an enhanced secretion of insulin in presence of 4mM glucose at 10-7 , 10-5 and 1O-4M muscimol. But in presence of 20mM glucose muscimol significantly inhibited the insulin secretion. GABAB agonist, baclofen also inhibited glucose induced insulin secretion in presence of both 4mM and 20mM glucose. This shows the inhibitory role of GABA and its specific receptor subtypes over insulin synthesis from pancreatic bete-islets. In vitro DNA synthesis studies showed that activation of GABAA receptor by adding muscimol, a specific agonist, inhibited islet DNA synthesis. Also, the addition of baclofen, a specific agonist of GABAB receptor resulted in the stimulation of DNA synthesis.Thus the brain and pancreatic GABAA and GABAB receptor gene expression differentially regulates pancreatic insulin secretion and islet cell proliferation during pancreatic regeneration. This will have immense clinical significance in therapeutic applications in the management of Diabetes mellitus.

5-HT1A and -HT2c Receptor Gene Expression: Their Functional Role in Pancreatic Regeneration and Insulin Secretion in Rats

Department of Biotechnology, Cochin University of Science and Technology

Muscarinic M1 Receptor Gene Expression in Streptozotocin Induced Diabetic Rats: Regulation of Insulin Secretion By Aegle marmelose And Costus pictus Leaf Extracts

The present work is to understand the alterations of total Muscarinic and Muscarinic MI receptors in brain and pancreatic islets of Streptozotocin induced diabetic rats. The work focuses on the evaluation of the antihyperglycemic activity of aqueous extracts of Aegle marmelose and Costus pictus leaves in vivo and the changes in the total Muscarinic and Muscarinic MI receptors during diabetes and after the treatment with insulin. The insulin secretory activity of Aegle marmelose and Costus pictus leaf extracts and the effect of cholinergic receptor agonist were investigated in vitro using rat primary pancreatic islet culture. Muscarinic MI receptor kinetics and gene expression during diabetes and regulation of insulin secretion by Aegle marmelose and Costus pie/us leaf extracts will help us to elucidate the role of Muscarinic and Muscarinic MI receptors in hyperglycemia and the regulatory activity of these plant extracts on insulin secretion through Muscarinic receptors.

“Adrenergic receptors and monoamines in the brain and pancreatic islets of streptozotoein diabetic rats: Role in insulin secretion as a function of age”

I) To study the changes in the content of brain rrrorroamirres in streptozotocirr-irrduced tliabetes as a lirnction of age and to lirrd the role oliadrenal lrornroncs in diabetic state. 2) To assess the adrenergic receptor function in the brain stem ofstreptozotocin-induced diabetic rats ofdillerent ages. 3) To study the changes in the basal levels of second messenger cAMP in the brain stenr ofstreptozotocin-induced diabetic rats as a function of age. 4) To study the changes occurring in the content ofmorroamines and their metabolites in whole pancreas and isolated pancreatic islets of streptozotocin-diabetic rats as a function ofage and the effect of adrenal hormones. 5) To study the adrenergic receptors and basal levels of cAMP in isolated pancreatic islets in young and old streptozotoein-diabetic rats. 6) The in virro study of CAMP content in pancreatic islets of young and old rats and its ellect on glucose induced insulin secretion. 7) 'lhe in vitro study on the involvement of dopamine and corticosteroids in glucose induced insulin secretion in pancreatic islets as a function of age.