PubMed Health⌕ Search

Biomedical subjects

J Purkiss

Publications and source records attributed to J Purkiss.

7 recordsLinked to original sources
PubMed2000

Capsaicin-stimulated release of substance P from cultured dorsal root ganglion neurons: involvement of two distinct mechanisms.

Capsaicin, the pungent component of "hot" chili peppers, selectively activates a distinct population of primary sensory neurons responsive to noxious stimuli. Many of these fibres express neuropeptides including the tachykinin, substance P. Using cultured dorsal root ganglion neurons, we found that capsaicin (10 microM) stimulated a 2-fold increase in release of substance P in the absence of extracellular Ca(2+). Elevated potassium (75 mM) was unable to induce release under these conditions. The introduction of Ca(2+) enhanced capsaicin-induced release and brought about a robust response to potassium. Preincubation of cells with botulinum neurotoxin A (100 nM) completely blocked potassium-induced release but the capsaicin response, in the absence of Ca(2+), was unaffected. However, toxin treatment dramatically reduced capsaicin-stimulated release in the presence of Ca(2+). It is concluded that capsaicin induces release of substance P from dorsal root ganglion neurons via two mechanisms, one requiring extracellular Ca(2+) and the intact synaptosomal-associated protein 25 kDa (SNAP-25), and the other independent of extracellular Ca(2+) and not involving SNAP-25.

Animals↗
PubMed1999

Cervical cancer screening knowledge and practices among Korean-American women.

Cervical cancer is one of the most common cancers of American women. The Papanicolaou (Pap) smear test for cervical screening is a widely used and effective means to reduce the morbidity and mortality rate from cervical cancer through early detection. Despite these benefits, many women have never been screened or are not screened at regular intervals. The purpose of this study was to examine cervical cancer screening knowledge and practices of Korean-American women. The sample consisted of 159 Korean-American women, 40 to 69 years of age. The 1987 Cancer Control Supplement questionnaire was translated into Korean and used to collect data. Twenty-six percent of the respondents never heard of the Pap smear test. Only 34% of respondents reported having had a Pap smear test for screening. The most frequently cited reason for not having had a Pap smear test was absence of disease symptoms. Results indicate that education and usual sources of health care were significant factors related to having heard of or having had a Pap smear test. The findings from this study have important implications for health practitioners and policy makers who serve this ethnic population.

Adult↗
PubMed1994

Influence of differing classes of antihypertensive agents on mesangial kinetics following partial renal ablation in rats.

Mesangial kinetics were studied in six groups of rats. Rats were either sham operated or were subjected to 1 1/3 nephrectomy (4/6 Nx). Each group was either untreated or was treated with enalapril (EN) or the drug regimen of hydralazine, hydrochlorothiazide, and reserpine (HHR). Four weeks after surgery rats were injected with iodinated aggregated bovine serum albumin (I-aggBSA) and mesangial localization quantified 2, 4, or 8 h later. Mesangial kinetics in untreated 4/6 Nx rats were characterized by accumulation of I-aggBSA to 4 h after injection with rapid clearance over the 4-8-h period; i.e. mesangial trafficking was increased following 4/6 Nx. Mesangial trafficking in 4/6 Nx rats treated with EN was reduced by virtue of lesser uptake of I-aggBSA at 4 h and retarded clearance over 4-8 h when compared with untreated 4/6 Nx animals. Treatment of 4/6 Nx rats with HHR maintained the increased trafficking observed in untreated 4/6 Nx rats. At 30 weeks untreated 4/6 Nx rats had severe albuminuria and glomerulosclerosis. Both indices of renal damage were significantly less in 4/6 Nx rats treated with enalapril. Treatment with HHR did not prevent albuminuria and had only limited effectiveness in preventing glomerulosclerosis. The different effects of EN and HHR on mesangial trafficking and glomerulosclerosis provide further evidence for a relationship between mesangial trafficking following partial renal ablation and subsequent development of glomerulosclerosis.

Albuminuria↗
PubMed1993

Mesangial kinetics after partial nephrectomy in rats fed a normal or a low-protein diet.

Mesangial kinetics of aggregated BSA (aggBSA) were studied in rats subjected to 1 1/3 nephrectomy (4/6 Nx) fed either a normal (16%) or a low-protein (8%) diet. At 4 weeks postsurgery, ablated rats exhibited modest elevations in blood pressure but had neither significant proteinuria nor evidence of glomerular damage. Following injection of aggBSA into 4/6 Nx rats (16% diet) there was a marked increase in mesangial localization at 4 h compared with control animals, followed by rapid clearance over 4-8 h, in keeping with increased trafficking in this model. The increased trafficking was significantly reduced by dietary protein restriction with 4/6 Nx rats fed an 8% protein diet exhibiting mesangial kinetics not significantly different from control animals. Control animals exhibited identical kinetics irrespective of diet. In separate studies, the 8% protein diet significantly reduced proteinuria and glomerulosclerosis when compared with untreated animals when studied at 30 weeks postsurgery.

Animals↗
PubMed1992

Stimulation of phosphatidic acid synthesis in bovine aortic endothelial cells in response to activation of P2-purinergic receptors.

In this study we used the bovine thoracic aorta endothelial cell line AG 4762 and primary bovine aortic endothelial cells to investigate the formation of phosphatidic acid (PA) in response to activation of P2-purinergic receptors. 2-Methylthio ATP (2MeSATP) stimulated the formation of [32P]-PA in bovine aortic endothelial cells labelled with 32P(i) for 2.5 hr. A comparison of the response to other ATP analogues suggests that this was mediated via a P2Y-purinergic receptor. Using various agonists at 30 microM there was a correlation between the formation of [32P]PA and of total inositol phosphates in the presence of lithium. The 2MeSATP-stimulated accumulation of [32P]PA showed an initial high rate, followed by a more sustained slower rate. The initial response was independent of extracellular calcium while the later response was dependent on calcium influx. The protein kinase C stimulator phorbol myristate acetate (PMA) produced only a very small enhancement of [32P]PA accumulation compared to 2MeSATP. The 2MeSATP stimulation of both inositol phosphates and [32P]PA was almost eliminated by the presence of PMA. Using cells prelabelled with [3H]methylcholine 2MeSATP produced only a small non-significant enhancement of [3H]choline formation; PMA by contrast formed a much larger amount of [3H]choline. There was no evidence of a change in [3H]phosphocholine. The dissociation between phospholipase D (PLD) activation and [32P]PA accumulation and the correlation between stimulation of [32P]PA accumulation and phospholipase C (PLC) activation all suggest that, using this protocol for labelling cells, the principle route of the stimulation of formation of [32P]PA is via the activation of PLC followed by metabolism of diacylglycerol (DAG) by DAG kinase. These results show that activation of P2Y-purinergic receptors on aortic endothelial cells leads to the formation of phosphatidic acid and that both PLD and PLC pathways are likely to contribute to this response.

Animals↗
PubMed1991

Lack of phospholipase D activity in chromaffin cells: bradykinin-stimulated phosphatidic acid formation involves phospholipase C in chromaffin cells but phospholipase D in PC12 cells.

The role of lipid-bound second messengers in the regulation of neurotransmitter secretion is an important but poorly understood subject. Both bovine adrenal chromaffin cells and rat phoeochromocytoma (PC12) cells, two widely studied models of neuronal function, respond to bradykinin by generating phosphatidic acid (PA). This putative second messenger may be produced by two receptor-linked pathways: sequential action of phospholipase C (PLC) and diacylglycerol kinase (DAG kinase), or directly by phospholipase D (PLD). Here we show that bradykinin stimulation of chromaffin cells prelabelled (24 h) with 32Pi leads to production of [32P]PA which is not affected by 50 mM butanol. However, bradykinin stimulation of PC12 cells leads to [32P]PA formation, all of which is converted to phosphatidylbutanol in the presence of butanol. When chromaffin cells prelabelled with [3H]choline were stimulated with bradykinin there was no enhancement of formation of water soluble products of phosphatidylcholine hydrolysis. When chromaffin cells were permeabilised with pneumolysin and incubated in the presence of [gamma-32P]ATP, the formation of [32P]PA was still stimulated by bradykinin. These results show that, although both neuronal models synthesize PA in response to bradykinin, they do so by quite different routes: PLC/DAG kinase for chromaffin cells and PLD for PC12 cells. The observation that neither bradykinin nor tetradecanoyl phorbol acetate stimulate PLD in chromaffin cells suggests that these cells lack PLD activity. The conservation of PA formation, albeit by different routes, may indicate an essential role of PA in the regulation of cellular events by bradykinin.

Adrenal Gland Neoplasms↗