PubMed Health⌕ Search

Biomedical subjects

N Shukla

Publications and source records attributed to N Shukla.

At least 37 records · Page 2Linked to original sources
PubMed1996

Determination of lead, zinc, potassium, calcium, copper and sodium in human cataract lenses.

Concentrations of Pb, Zn, K, Ca, Cu and Na were determined in several human cataract and clear lenses, obtained from patients from two contrasting environmental regions in India, and the values were compared. When compared with the results obtained for samples of clear lenses, the mean concentration values of cataract lenses showed significant changes on the basis of the Mann-Whitney test. In cataract lenses, Pb and Zn showed an inverse correlation of r = -0.83; y = -1.64x + 457. Ca and K also showed an inverse correlation of r = -0.71; y = -0.34x + 3.6. No significant correlations were found between any other elements. The distribution of Pb, Zn, Ca and K were studied and their importance in ocular tissues is discussed. The molecules present in the eye lens lattice have undergone some conformational alterations due to intrusion of Pb and Ca ions and extrusion of Zn and K ions through the process of ion-exchange, thereby influencing the transparency of the lens.

Aged↗
PubMed1996

Human liver cancer cells and endothelial cells incorporate iodised oil.

Iodised oil (lipiodol) administered via the hepatic artery localises selectively in primary liver cell cancers (hepatocellular carcinomas or HCCs) for prolonged periods and has been used as a vehicle for cytotoxic agents. Despite clinical use, the mechanism of lipiodol retention by tumours has remained unclear, embolisation of oil droplets in the tumour vasculature being the prevailing hypothesis. We have investigated the role of tumour and endothelial cells in lipiodol retention. Human liver tumour (Hep G2) cells and human umbilical vein endothelial cells in culture were exposed to lipiodol. Light microscopy using selective silver impregnation stains and transmission electron microscopy revealed lipiodol incorporation by both cell types, probably by pinocytosis. This was not associated with cellular injury in terms of cell lysis, cell replication or radio-labelled leucine uptake. Histological analysis of 24 HCCs either surgically resected or discovered incidentally at liver transplantation (with prior arterial injection of lipiodol) revealed vesicles of lipiodol in the cytoplasm of tumour cells and endothelial cells lining tumour vessels. Thus, lipiodol is likely to deliver cytotoxic agents directly into tumour cells and endothelial cells, both in vitro and in vivo. This may also apply to other lipids and to other human tumours. These findings have significant therapeutic implications.

Carcinoma, Hepatocellular↗
PubMed1996

A study of peripheral nerve function in neonates and infants.

Motor and sensory nerve conduction velocity, H-reflex and F-response have been studied in the age group showing maximum changes i.e. neonates and infants. The nerve conduction velocity in upper and lower limbs was 25 M/S and 23.75 M/S respectively in neonate age group; 34.4 M/S and 32.4 M/S respectively in infant group. A significant relationship of age with nerve conduction parameters (velocity, terminal latency) has been observed in infants group but not so in neonate group. H-reflex (late response) was elicited in both Abductor Pollicis Brevis and Soleus. It was present in small muscles of hand (i.e. APB) in all the neonates and 55% of the infants only. This could be attributed to immaturity of nervous system. However, in the lower limb, H-reflex could be elicited in 100% of infants and neonates. In the present study, the relationship of age and height with different nerve conduction parameters as well as H-reflex (latency) has been highlighted.

Aging↗
PubMed1995

Pulmonary function tests in normal Indian children and changes in respiratory disorders.

To document the normal values of pulmonary function tests in children and changes occurring in their values with various respiratory disorders, a study was carried over a period of one year in 95 healthy controls (39 females and 56 males) of 8-13 years of age and 51 cases with respiratory disorders (bronchial asthma-31, pneumonia-10, empyema-10) of matched age, sex and height distribution. The lung functions studied were FVC, FEV1, FEV1/FVC, PEFR and FEF25-75%. In children with bronchial asthma, the FEV1/FVC%, PEFR and FEF25-75% were reduced in accordance with the severity of the disease. A typical restrictive pattern of equivalent decrease in FVC and FEV1 along with insignificant lowering of flow rates, i.e., PEFR and FEF25-75% was observed in pneumonia whereas in patients of empyema a combined pattern of significantly decreased FVC and FEV1 along with mildly reduced FEV1/FVC%, PEFR and FEF 25 75% was observed.

Analysis of Variance↗
PubMed1994

Endothelial seeding of compliant polyurethane vascular graft material.

Compliance was measured in a new compliant polyurethane vascular graft material and in polytetrafluoroethylene (PTFE) graft material using an ultrasonic device; attachment of indium-111 oxine-labelled human endothelial cells to both surfaces with a range of surface coatings was assessed. Compliant polyurethane was six to eight times more compliant than PTFE (P < 0.01) at all pressures in the range 50-120 mmHg, and endothelial cell attachment to uncoated polyurethane was three times better than to uncoated PTFE at times up to 90 min (P < 0.01). Attachment to polyurethane was also better after blood clot, collagen and fibronectin treatment at times up to 30 min (P < 0.05). Endothelial seeding of compliant graft material may provide a prosthetic vascular substitute with characteristics similar to those of autologous vein.

Aged↗
PubMed1993

Examination stress in medical student: a study.

The present study was conducted on 40 male and 10 female students appearing for the 1st MBBS examination. Two readings of pulse rate, blood pressure and electro cardiogram were taken viz 6 months (control) and 10 minutes prior to the examination. A significant increase was seen in the pulse rate and blood pressure readings before the examination as compared to the control readings. However, no significant change was observed in electro cardiographic recordings.

Adolescent↗
PubMed1992

5-Hydroxytryptamine stimulates 45Ca2+ uptake by human umbilical vein endothelial cells in culture: mediation by 5-HT2 receptor subtypes.

In cultured human umbilical vein endothelial cells, 5-HT and alpha-methyl 5-HT stimulated [45Ca2+] uptake in concentration-dependent manner, whereas the 5-HT1 agonists, m-CPP (1-(3-chlorophenyl)piperazine and 2-MPP (1-(2-methoxyphenyl)piperazine), were without effect. In turn, 5-HT-stimulated [45Ca2+] uptake was inhibited in concentration-dependent manners by the 5-HT receptor antagonists ketanserin (5-HT2), LY 53,857 (5-HT2) and methiothepine (5-HT1/2) and to a lesser degeree by MDL 72222 (5-HT3) and BRL 43694 (5-HT3) whereas (+/-)-propranolol (5-HT1) was without effect. These data indicate that 5-HT stimulates Ca2+ uptake by endothelial cells via activation of a 5-HT2 receptor subtype. 5-HT was without effect on de novo prostacyclin (PGI2) synthesis over the concentration of 5-HT that elicited [45Ca2+] uptake. Since 5-HT did not stimulate PGI2, an event associated with an increase in levels of intracellular Ca2+, it is postulated that the uptake of 45Ca2+ reflects changes of Ca2+ at the level of the plasma membrane rather than on intracellular changes. 5-HT-stimulated Ca2+ uptake may be of relevance to endothelium-dependent relaxation, vascular permeability and endothelial repair and proliferation.

Biological Transport, Active↗
PubMed1991

Seeding of human microvascular endothelial cells onto polytetrafluoroethylene graft material.

Microvascular endothelial cells from human omental samples were isolated and grown. Adhesion to polytetrafluoroethylene vascular graft material was then studied using scanning electron microscopy and adhesion of cells labelled with indium-111. Grafts coated with fibronectin and type I collagen were found to promote the best adhesion of cells at times up to 90 min. A coating of blood clot matrix was less effective but still resulted in a threefold increase in cell adhesion compared with controls.

Blood Vessel Prosthesis↗
PubMed1991

Comparison of prostanoid synthesis in cultured human vascular endothelial cells derived from omentum and umbilical vein.

Endothelial seeding of vascular grafts may reduce thrombogenicity and significantly improve graft patency. For clinical studies endothelial cells derived from human omentum may be the ideal source of cells as they are obtainable in large numbers. This study was designed to assess their ability to produce the antithrombogenic substance prostacyclin (PGI2). Human omental microvascular endothelial cells (HOTMECs) were grown and their ability to produce prostacyclin (PGI2), PGE2, PGF2 alpha and thromboxane A2 (TXA2) in response to a range of agonists was measured by radioimmunoassay. Control experiments were performed using human umbilical vein endothelial cells (HUVECs). Both HUVECs and HOTMECs synthesised similar quantities of PGI2 basally and both increased production after adding A23187 (calcium ionophore), arachidonic acid, sodium fluoride and phorbol ester. In contrast, both thrombin and histamine were potent stimulators of PGI2 release in HUVECs but were without effect on HOTMECs. In both cell types serotonin, carbachol and noradrenaline were without effect. The pattern of release of PGE2, PGF2 alpha and TXA2 were identical to those of PGI2 in both cell types but the quantities released were lower. These results show that HOTMECs can produce the antithrombogenic agent PGI2 in significant quantities and that they do so by mechanisms similar to those of large vessel endothelium. This supports the proposal that they would be a suitable cell source for vascular graft seeding.

Cells, Cultured↗
PubMed1989

Influence of age and exercise training on lipid metabolism in Fischer-344 rats.

The influence of training on fatty acid and glyceride synthesis by liver and adipose tissue homogenates of young and old Fischer-344 rats was examined. Four groups of rats (10 animals/group) were studied: young untrained, young trained, old untrained, and old trained. Training of each group was for 10 wk at 75% maximal O2 uptake. Young rats were killed at 6 mo of age and old rats were killed at 27 mo of age. Fatty acid synthesis was assessed by measuring the activities of acetyl-CoA carboxylase, fatty acid synthase, ATP citrate-lyase, "malic" enzyme, and glucose-6-phosphate dehydrogenase. Glyceride synthesis was evaluated by determining the rate of incorporation of [14C]glycerol 3-phosphate into lipids. In addition, lipoprotein lipase activity was measured in acetone-ether powders of adipose tissue from the four groups of rats. In liver, training had no effect on fatty acid or glyceride synthesis in either group. However, aging caused a significant decrease in the activities of four of the lipogenic enzymes but had no effect on glyceride synthesis. Training caused an increase in fatty acid synthase and glyceride synthesis in adipose tissue, and aging decreased lipoprotein lipase activity. It was concluded that training enhances the synthetic capacity of lipids by adipose tissue but that aging had a more profound effect in that the activities of the enzymes involved in these processes were lower in the old rats. Furthermore, the decreased activity of lipoprotein lipase in the older rats may explain the higher plasma triglyceride levels that were observed in these animals.

ATP Citrate (pro-S)-Lyase↗
PubMed1989

Central actions of angiotensin II on heart rate and blood pressure in mongrel dogs.

Angiotensin II is produced physiologically in response to renal ischaemia due to hypotension. It's effect on heart rate and blood pressure were studied on anaesthetised mongrel dogs. Angiotensin II was given in different concentrations, by intravenous, intraarterial in carotid artery and intracerebroventricular routes. Cervical vagotomy and carotid sinus inactivation were done is abolish the reflex inhibition produced by baroreflexes. Rise of B.P. is due to mainly peripheral vasopressor action of angiotensin II, however it is shown to have a central component as well. This is demonstrated by ICV injections. Tachycardia due to central action is also demonstrated in this study. Both actions are significant. This study also confirm the earlier findings that angiotensin II passes the blood brain barrier.

Angiotensin II↗
PubMed1989

Role of dopaminergic system in opioid-induced cardiovascular responses in dogs.

A study was carried out to determine the involvement of dopaminergic system in opioid-induced cardiovascular responses in the dogs. The study population consisted of 32 mongrel dogs of either sexes. The results show that morphine given in small dose (2 mg/kg I.V.) causes significant fall in blood pressure. The results also show that there is involvement of dopaminergic system in opioid-induced vasomotor responses in dogs. Partial blockade of the parenterally induced hypotensive response of morphine by haloperidol given centrally induced hypotensive responses of morphine by haloperidol given centrally in doses, which are too low to be effective by the peripheral route, strongly favours the involvement of central dopaminergic system in the morphine-induced hypotensive responses. The results also show that the hypotensive response of morphine was almost completely blocked after naloxone pretreatment by central route.

Animals↗