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Biomedical subjects

K Shanker

Publications and source records attributed to K Shanker.

At least 55 records · Page 3Linked to original sources
PubMed1991

Platelet norepinephrine efflux in thrombotic stroke.

Twenty CT proven patients of thrombotic stroke who were non-diabetic, non-hypertensive and non-hyperlipidemic were evaluated in acute phase (within 7 days of onset of neurological deficit) for platelet count and spontaneous platelet norepinephrine (NE) efflux, measured as the fraction (of initial total content) of 3H-NE released from platelets in 30 and 60 min. NE efflux was significantly greater (P less than 0.001) in stroke patients (34.09 +/- 4.92% at 30 min and 50.45 +/- 7.1% at 60 min) as compared to controls (23.27 +/- 4.16% at 30 min and 39.49 +/- 3.27% at 60 min). This excessive efflux may result in increased concentrations of NE in local plasma, which by causing enhanced platelet aggregation and damage to vascular endothelium and vasospasm, may contribute towards the development and progression of cerebral thrombosis.

Blood Platelets↗
PubMed1990

Platelet serotonergic mechanisms in ischaemic heart disease.

The uptake, basal content and efflux of serotonin (5-HT) from the platelets of patients of ischaemic heart disease (I.H.D.) was studied and compared with normal platelets. A significant increase in uptake and basal content of 5-HT as well as increase in 5-HT efflux was observed as compared to control. Our data indicate that I.H.D. is associated with platelet serotonergic dysfunction which seems to indicate that the platelets are preactivated in I.H.D.

Angina Pectoris↗
PubMed1990

Kinetics of serotonin in platelets in essential hypertension.

In a study of the kinetics of 5-hydroxytryptamine (5-HT) in platelets in 26 hypertensive subjects with a mean systolic and diastolic blood pressure of 153.9 +/- 26.9 and 106.9 +/- 9.1 mm Hg respectively, it has been observed that in hypertensive platelets there was a marked decrease in 5-HT uptake and content, an increase in 5-HT efflux and an accompanying increase in Plasma 5-HT and 5-HIAA levels. Regression analysis of the data indicated a significant correlation between rise in diastolic blood pressure and these changes in 5-HT kinetics.

Blood Platelets↗
PubMed1990

Platelet ionic calcium and serum total calcium in essential hypertension.

A total of 44 cases comprising hypertensive (31) and normotensive group (13) were studied. Serum total calcium concentrations remained unaltered in hypertensives. Platelet cytosolic calcium in hypertensive group was significantly higher as compared to the normotensive controls. Platelet cytosolic calcium correlated with systolic and diastolic blood pressure and mean arterial pressure significantly.

Blood Platelets↗
PubMed1989

Platelet serotonergic mechanisms and glomerulonephritis.

Proven cases (28) of glomerulonephritis (GN) were evaluated for clinico-biochemical profile, bleeding time, platelet count, platelet aggregation and platelet serotonergic mechanisms. Inordinate increase in platelet aggregation and altered platelet serotonergic mechanisms (reduced 5-HT, uptake, reduced intraplatelet 5-HT and increased plasma 5-HT) were demonstrated in some histopathological types of GN. The mechanisms and importance of these alterations have been discussed.

Bleeding Time↗
PubMed1987

Antiparkinsonian activity and behavioural effects of newer quinazolinones.

Sixteen new compounds 2-methylamino substituted phenyl-3-substituted anilino 4 (3H) quinazolinones (3-18) were prepared. All the compounds were evaluated for their antiparkinsonian activity and compared with bromocriptine. Compounds 10,15 and 18 showed better activity. These compounds also bind with the dopamine receptors in striatal membrane preparations of rat brain.

Animals↗
PubMed1987

Serotonin in tension headache.

Serotonin (5-hydroxytryptamine, 5-HT) is implicated in the pathogenesis of migraine; however, its role in tension headache has not yet been studied. The uptake of 5-HT by platelets in patients of tension headache was significantly higher compared with migraineurs as well as controls. The basal platelet 5-HT levels did not show a significant difference. The study implicates the role of serotonin in tension headache.

Adult↗
PubMed1986

Sulphinpyrazone and the platelet serotoninergic mechanism in ischaemic heart disease.

A double blind study in 25 patients with ischaemic heart disease and 20 matched healthy controls examined the effect of sulphinpyrazone on the uptake of serotonin by platelets and the basal concentrations of serotonin in platelets. Uptake was measured using tritium labelled serotonin and basal concentrations estimated spectrophotofluorometrically. Serotonin uptake was significantly increased both in the patients with chronic stable angina of effort and in those with a history of myocardial infarction six months or more previously. Sulphinpyrazone reduced serotonin uptake from 94.25 (SE 8.65) to 57.86 (5.37) cpm/10(8) platelets after 24 weeks of treatment in the group with stable angina and from 137.45 (16.26) to 68.08 (8.38) cpm/10(8) platelets in the myocardial infarction group. Raised basal concentrations in the two groups were also reduced by sulphinpyrazone. Placebo had no effect on serotonin uptake or basal concentrations in either group of patients. The ability of sulphinpyrazone to inhibit uptake and reduce basal concentrations of serotonin in patients with ischaemic heart disease may be yet another mechanism through which this drug exerts its beneficial antiplatelet effect.

Adult↗
PubMed1986

Endosulfan induced inhibition of 3H-5-hydroxytryptamine uptake in platelets.

Endosulfan, a chlorinated pesticide, is widely used to control various insect pests. Rats exposed to 1 mg and 3 mg endosulfan/kg for periods of 10, 30, and 60 days showed significant (P less than 0.05) inhibition of [3H]5-hydroxytryptamine (5-HT) uptake by platelet-rich plasma (PRP) in an ex vivo study. Rats treated with endosulfan (1 and 3 mg/kg) up to 60 days elucidated a marked inhibition of ADP-induced aggregatory responses of the platelets. Incubation of PRP with 10 microM and 100 microM endosulfan for 15 min at 37 degrees C also resulted in significant (P less than 0.05) inhibition of platelet aggregation in vitro. The paper discusses the use of rat blood platelets as a model for the study of neuro- and cardiovascular toxicity of endosulfan.

Animals↗
PubMed1985

Effect of alcohols on the permeability of blood-brain barrier.

Effect of alcohols on the permeability of blood-brain barrier was studied in anaesthetised dogs using sodium fluorescein as circulant. Entry of sodium fluorescein in the cerebrospinal fluid (CSF) was measured spectrophotofluorometrically. Methyl, ethyl, propyl and butyl alcohols were used in the study. Methyl alcohol did not increase the entry of sodium fluorescein in CSF compared to control. However, ethyl, propyl and butyl alcohols significantly increased the entry of sodium fluorescein. The increase was dependent upon the length of alkyl chain of alcohols. Longer was the aliphatic chain more marked was the effect. The increase in permeability was also dependent upon the concentration of the alcohol. Thus 90% ethyl alcohol was more effective than 30% and this effect was concentration-dependent. The increase in permeability of blood-brain barrier could be correlated to the lipid solubility of alcohols.

1-Propanol↗
PubMed1985

Involvement of catecholamines and serotonin in human hypertension.

Lumber cerebrospinal fluid (CSF) concentrations of metabolites of noradrenaline, adrenaline and serotonin were estimated in patients of sustained hypertension (n = 20), and healthy controls (n = 15). Platelet uptake of serotonin and its basal contents were also estimated in the same individuals. CSF 5-hydroxy indole acetic acid level (5-HIAA) (major metabolite of serotonin) was significantly higher in hypertensives than controls (p less than .01). CSF 3-methoxy, 5-hydroxy phenyl glycol (MHPG) (major metabolite of adrenaline and noradrenaline) level was also raised significantly in cases of hypertension (p less than .01). However, platelet uptake of serotonin as well as its basal contents in hypertension were significantly lower than controls (p less than .01). It can thus be postulated that there exists an increased central serotonergic and catecholaminergic activity in hypertension. Furthermore, alterations observed in platelet serotonin uptake and its basal content suggest the involvement of platelet serotonergic system in hypertension.

Adult↗