Differential effects of insulin-sensitizers troglitazone and rosiglitazone on ion currents in rat vascular myocytes

Insulin-sensitizing thiazolidinediones such as troglitazone and pioglitazone have been shown to lower blood pressure in vivo and cause vasorelaxation in vitro. Rosiglitazone (BRL 49653) is a novel thiazolidinedione which has been reported not to cause vasoleraxation. We therefore compared the effects of troglitazone and rosiglitazone on Ca2+ and K+ currents in rat aorta and pulmonary artery smooth muscle cells. Currents were recorded with the conventional whole cell patch clamp technique. Both drugs reduced the voltage-gated (L-type) Ca2+ current in rat aorta cells, with half-maximal current inhibition by troglitazone and rosiglitazone at 2 and 10 microM, respectively. Troglitazone, 2 microM and rosiglitazone, 20 microM caused a similar hyperpolarizing shift of 12 mV in the potential-dependence of Ca2+ current availability. Troglitazone (20 microM) produced a marked block of the tetraethylammonium- and paxilline-sensitive Ca2+ activated K+ current, while rosiglitazone (20 microM and 60 microM) slightly enhanced this current. Rat pulmonary artery smooth muscle cells have a prominent delayed rectifier K+ current. Troglitazone produced a potent block of this current (half-maximal inhibition at <1 microM), while rosiglitazone caused a smaller inhibition at 10 and 60 microM. These results show that troglitazone has relatively potent blocking effects on a wide variety of ion currents in vascular smooth muscle cells. Rosiglitazone exerts less potent, but similar effects on the Ca2+ current and delayed rectifier K+ current, but it enhances the Ca2+ activated K+ current. reserved.     

Differential block by troglitazone and rosiglitazone of glibenclamide-sensitive K(+) current in rat aorta myocytes

Thiazolidinediones are insulin-sensitising agents effective in controlling type II diabetes. These compounds also cause vasodilation. We evaluated the effects of the thiazolidinediones troglitazone and rosiglitazone on the glibenclamide-sensitive K(+) current in freshly isolated rat aorta myocytes. Troglitazone inhibited this current in a concentration-dependent manner (IC(50) approximately 1 microM). Rosiglitazone had a similar, but much less potent (IC(50) approximately 20 microM) action. Block of the glibenclamide-sensitive K(+) channels, in particular by troglitazone, may potentially affect the response of arteries to hypoxia and to certain endogenous and exogenous vasodilators.     

Diagnostic significance of vestibular tests in posterior fossa tumefaction

Abnormal vestibular responses are observed more frequently in cerebellar and Brain stem lesions than in cerebello-pontine angle tumours. The direction of spontaneous, positional, positioning nystagmus or caloric induced directional preponderance are not quite reliable in topographical localisation of these lesions. Hyperreflexia and dysarhythmia of thermally induced nystagmus are reasonably reliable evidences of affections of cerebellum or its connections. The deficiency of the fast phase of nystagmus indicates a bulbopontine lesion.     

Modification of vascular response to synthetic oxytocin by oestrogen in rabbit

Intravenously administered oxytocin caused a dose-related fall in blood pressure of the rabbit. When oxytocin was administered in oestrogen-primed animals, the depressor response was converted to a pressor one "Oxytocin reversal". The "oxytocin reversal." was abolished after treatment with dihydroergotamine, hexamethonium or adrenalectomy. The "oxytocin reversal" did not appear in reserpinized animals.     

Telemedice in otolaryngology (An Indian Perspective)

Telemedicine is an upcoming concept in the modem world, It needs to be inculcated to improve the coordination amongst the health care providers in order, not only to update themselves but also to provide a coordinated approach far eatering masses in a developing country The various advantages and drawbacks are highlighted, and stress is made on starting a remote method of tetecommunication amongst us.     

Pharmacokinetics, in-situ absorption and protein binding studies of a new neuroleptic agent centbutindole in rats.

The present study reports the absorption kinetics, plasma protein binding and pharmacokinetic profile of the centbutindole (I) after i.v. and oral dosing in rats. In addition, an in-situ absorption study was carried out using a closed-loop technique at pH 2.6 and 7.4. The rate of absorption at pH 2.6 was 5-fold less compared to that observed at pH 7.4. In-vitro and in-vivo protein binding (ultra filtration technique) was independent of substrate concentration over a range of 1.25-10.0 microg/ml. Pharmacokinetic parameters of I were determined in male rats after administering a single 4 mg/kg oral dose and 2 mg/kg intravenous dose. The peak serum concentration of I was found to be 50.1 ng/ml at 30 min after oral administration followed by a secondary Cmax of 43.2 ng/ml at 180 min. For the hydroxy metabolite (II), a Cmax of 6.4 ng/ml was measured at 360 min after oral administration of I. After oral dosing an irregular concentration-time profile with secondary peaks was observed for both I and II. The terminal half-lives for I and II after oral dosing were 163 and 263 min, respectively. After intravenous dosing, the levels of I decreased biexponentially with a distribution (t(1/2) alpha) and elimination (t(1/2) beta) half-lives of 5.7 and 128 min, respectively. Comparison of the AUC after oral and intravenous dosing of I indicates that only about 24% of the oral dose reaches the systemic circulation. The limited bioavailability can either be due to the poor solubility of the compound and/or extensive first pass metabolism in the gastrointestinal (GI) tract. Co-administration of polyethylene glycol (PEG) at oral dosing improves solubilization and increases bioavailability.     

A farnesyltransferase inhibitor increases survival of mice with very advanced stage acute lymphoblastic leukemia/lymphoma caused by P190 Bcr/Abl.

Treatment of chronic myelogenous leukemia with a specific inhibitor of the Bcr/Abl tyrosine kinase, imatinib, has shown great promise. However, acute lymphoblastic leukemias that express Bcr/Abl only transiently respond to imatinib. Therefore, alternative treatments for this type of leukemia are urgently needed. Here, we examined the activity of the farnesyltransferase inhibitor SCH66336 as a single chemotherapeutic agent in a nude mouse model representative of very advanced stage Bcr/Abl P190-positive lymphoblastic leukemia/lymphoma. Our results show that oral administration of the inhibitor was able to significantly increase the survival of these mice compared to controls treated with vehicle (P<0.005), and caused marked regression of the tumor burden in the treated mice. Upon prolonged treatment, lymphomas re-emerged and a subset of cells from two of such lymphomas tested was able to survive in the presence of increased concentrations of SCH66336. The same cells, however, remained sensitive towards imatinib. A combination of the two drugs, preceded by a therapy to reduce the initial tumor burden, could be very effective in the treatment of Ph-positive ALL. We conclude that SCH66336, on its own, is remarkably effective in eradicating large numbers of lymphoblastic lymphoma cells and causing visible reduction in tumor size, with minimal toxicity.     

Myxoma of maxilla

A case of Myxoma involving left Maxilla, presenting as swelling of left side of face and Oral cavity with bilateral nasal obstruction is reported.