Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction

Histamine is a transmitter in the nervous system and a signaling molecule in the gut, the skin, and the immune system. Histaminergic neurons in mammalian brain are located exclusively in the tuberomamillary nucleus of the posterior hypothalamus and send their axons all over the central nervous system. Active solely during waking, they maintain wakefulness and attention. Three of the four known histamine receptors and binding to glutamate NMDA receptors serve multiple functions in the brain, particularly control of excitability and plasticity. H1 and H2 receptor-mediated actions are mostly excitatory; H3 receptors act as inhibitory auto- and heteroreceptors. Mutual interactions with other transmitter systems form a network that links basic homeostatic and higher brain functions, including sleep-wake regulation, circadian and feeding rhythms, immunity, learning, and memory in health and disease.

Histamine in the Nervous System

The prevalence of the metabolic syndrome, a cluster of cardiovascular risk factors associated with obesity and insulin resistance, is dramatically increasing in Western and developing countries. This disorder consists of a cluster of metabolic conditions, such as hypertriglyceridemia, hyper-low-density lipoproteins, hypo-high-density lipoproteins, insulin resistance, abnormal glucose tolerance and hypertension, that-in combination with genetic susceptibility and abdominal obesity-are risk factors for type 2 diabetes, vascular inflammation, atherosclerosis, and renal, liver and heart diseases. One of the defects in metabolic syndrome and its associated diseases is excess of reactive oxygen species. Reactive oxygen species generated by mitochondria, or from other sites within or outside the cell, cause damage to mitochondrial components and initiate degradative processes. Such toxic reactions contribute significantly to the aging process. In this article we review current understandings of oxidative stress in metabolic syndrome related disease and its possible contribution to accelerated senescence.

Metabolic Syndrome, Aging and Involvement of Oxidative Stress

How to investigate drug use in health facilities : selected drug use indicators

Polymeric micelles represent an effective delivery system for poorly water-soluble anticancer drugs. With small size (10–100 nm) and hydrophilic shell of PEG, polymeric micelles exhibit prolonged circulation time in the blood and enhanced tumor accumulation. In this review, the importance of rational design was highlighted by summarizing the recent progress on the development of micellar formulations. Emphasis is placed on the new strategies to enhance the drug/carrier interaction for improved drug-loading capacity. In addition, the micelle-forming drug-polymer conjugates are also discussed which have both drug-loading function and antitumor activity.

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Polymeric Micelles: Nanocarriers for Cancer-Targeted Drug Delivery

This study was designed to examine the antioxidant defense by ethanolic extract of Embelia ribes on streptozotocin-(40 mg/kg, intravenously, single-injection) induced diabetes in Wistar rats. Forty days of oral feeding the extract (100 mg/kg and 200 mg/kg) to diabetic rats resulted in significant ( P .01 ) decrease in blood glucose, blood glycosylated haemoglobin, serum lactate dehydrogenase, creatine kinase, and increase in blood glutathione levels as compared to pathogenic diabetic rats. Further, the extract also significantly ( P .01 ) decreased the pancreatic thiobarbituric acid-reactive substances (TBARS) levels and significantly ( P .01 ) increased the superoxide dismutase, catalase, and glutathione levels as compared to above levels in pancreatic tissue of pathogenic diabetic rats. The islets were shrunken in diabetic rats in comparison to normal rats. In the drug-treated diabetic rats, there was expansion of islets. The results of test drug were comparable to gliclazide (25 mg/kg, daily), a standard antihyperglycemic agent. The study concludes that Embelia ribes enhances the antioxidant defense against reactive oxygen species produced under hyperglycemic condition and this protects β -cells against loss, and exhibit antidiabetic property.

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Further studies on antioxidant potential and protection of pancreatic beta-cells by Embelia ribes in experimental diabetes.

Diabetes mellitus has been treated orally with herbal remedies based on folk medicine since ancient times. Embelia ribes burm (Myrsinaceae), known commonly as vidanga, was used in Ayurveda for its anthelmintic activity. Ayurveda describes vidanga as pungent, causes increase in digestive fire, and cures flatulence and colic. A single study reported the antihyperglycemic activity of decoction of E. ribes in glucose-induced hyperglycemic albino rabbits. In the present study, the lipid-lowering and antioxidant potential of ethanolic extract of E. ribes burm was investigated in streptozotocin (40 mg/kg, IV, single injection)-induced diabetes in rats. Twenty days of orally feeding the extract (200 mg/kg) to diabetic rats resulted in significant (P < 0.01) decrease in blood glucose, serum total cholesterol, and triglycerides, and increase in HDLcholesterol levels when compared to pathogenic diabetic rats. Further, the extract also lowered the liver and pancreas thiobarbituric acid–reactive substances (TBARSs) values (P < 0.01) when compared to TBARS values of liver and pancreas of pathogenic diabetic rats. The results of test drug were comparable to gliclazide (25 mg/kg, orally), a standard antihyperglycemic agent. This is the first pilot study to provide biochemical evidence of potential of E. ribes in diabetic dyslipidemia.

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Effect of ethanolic extract of Embelia ribes on dyslipidemia in diabetic rats.

Ethanolic Z. officinale (ZO) extract (200 mg/kg) pretreatment for 20 days in isoproterenol (ISO)-treated rats significantly increased the levels of endogenous myocardial antioxidants (catalase, superoxide dismutase and tissue glutathione), decreased the levels of serum marker enzymes (lactate dehydrogenase, creatine kinase, aspartate transaminase and alanine transaminase) and increased myocardial lipid peroxides. Histological examination of rat's heart section confirmed myocardial injury with ISO administration and near normal pattern with ethanolic ZO extract pretreatment. The results of the present study, for the first time, provide clear evidence that the ethanolic ZO extract pretreatment enhances the antioxidant defense against ISO-induced oxidative myocardial injury in rats and exhibit cardioprotective property.

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Ethanolic Zingiber officinale R. extract pretreatment alleviates isoproterenol-induced oxidative myocardial necrosis in rats.

The interaction of selective histamine H3-receptor agonist R(alpha)-methyl-histamine (RAMH) and antagonist thioperamide (THP) with some antiepileptic drugs [AED; phenytoin (PHT), carbamazepine (CBZ), sodium valproate (SVP), and gabapentin (GBP)] was studied on seizures induced by maximal electroshock (MES) and pentylenetetrazole (PTZ) in mice. It was found that subeffective dose of THP in combination with the subeffective doses of PHT and GBP provided protection against MES and/or PTZ-induced seizures. Further, RAMH reversed the protection afforded by either PHT or GBP on MES and/or PTZ seizures. In another set of experiments, the histamine content was measured in the whole brain and in different brain regions including cerebral cortex, hypothalamus, brain stem and cerebellum following convulsant (MES and PTZ) and AED treatment. It was seen that while MES exhibited a tendency to enhance brain histamine levels, PTZ showed the opposite effect. AEDs either increased (PHT and GBP) or decreased (SVP) brain histamine content in different regions to varying degrees. The results indicate a role for histamine in seizures and in the action of AEDs and suggest that selective H3-receptor antagonists may prove to be of value as adjuncts to conventional AEDs.

Histamine and selective H3-receptor ligands: a possible role in the mechanism and management of epilepsy.

Summary
Background: India has witnessed a rapidly exploding epidemic of diabetes in recent years and currently leads the world with the largest number of diabetic subjects in a single country. World Health Organization estimates that in 2000, 31·7 million individuals were affected by diabetes in India and these numbers will rise to 79·4 millions by the year 2030. In view of the above situation, drug utilization review of antidiabetic medicines in Indian healthcare settings has a valid significance to promote rational drug use in diabetics.

Objective:  The present study is aimed to determine the drug utilization patterns in type 2 diabetic patients on oral hypoglycemic agents in the Medicine Outpatient Department (OPD) and Inpatient Department (IPD) of Majeedia Hospital, a teaching hospital of Hamdard University, New Delhi.

Methods:  Patients with established type 2 diabetes (n = 218) visiting the OPD and IPD were interviewed using a structured questionnaire during the period January–May 2006.

Results:  A majority of the type 2 diabetic patients in this setting were treated with multiple antidiabetic drug therapy. The most commonly prescribed antidiabetic drug class was biguanides (metformin) followed by sulphonylureas (glimepiride), thiazolidinediones (pioglitazone), insulin and alpha-glucosidase inhibitors (miglitol). As monotherapy insulin was the most common choice followed by metformin. The most prevalent multiple therapy was a three-drug combination of glimepiride + metformin + pioglitazone. More than half of the type 2 diabetic patients showed poor adherence (compliance) to the prescribed therapy.

Conclusion:  This study strongly highlights the need for patient education or counselling on use of antidiabetic and concomitant drugs, monitoring of blood glucose and glycosylated haemoglobin (HbA1c) levels, diet control, and correction of diabetic complications. Metabolic control was poor and HbA1c monitoring was underutilized. Clinical monitoring of patients’ adherence to prescribed treatments is recommended and measures should be taken to improve it.

K. K. Pillai

Papers

Further studies on antioxidant potential and protection of pancreatic beta-cells by Embelia ribes in experimental diabetes.

Effect of ethanolic extract of Embelia ribes on dyslipidemia in diabetic rats.

Ethanolic Zingiber officinale R. extract pretreatment alleviates isoproterenol-induced oxidative myocardial necrosis in rats.

Histamine and selective H3-receptor ligands: a possible role in the mechanism and management of epilepsy.

Drug utilization of oral hypoglycemic agents in a university teaching hospital in India