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P Vadas

Publications and source records attributed to P Vadas.

At least 73 records · Page 4Linked to original sources
PubMed1989

Multiple forms of phospholipase A2 in arthritic synovial fluid.

Phospholipase A2 (PLA2) has been purified to homogeneity from human arthritic synovial fluid. The activity resolved into multiple peaks by preparative HPLC. The most abundant peak (A) was present in synovial fluid from patients with rheumatoid arthritis, osteoarthritis, and psoriatic arthritis. A second major peak (B) was variable and lower in relative abundance, but was distinguishable from peak A by its stimulated activity in the presence of either 0.5 M Tris or 0.1% sodium deoxycholate (DOC), in addition to its longer HPLC column retention time. Both peaks required Ca2+ and showed optimal activity in DOC/phosphatidylcholine (PC) mixed micelle assays between pH 8.0 and 9.0. Both peaks showed higher activity with PC as substrate than with PI, however peak A exhibited higher activity with PE than PC. Upon preparative SDS-polyacrylamide gel electrophoresis, both peaks of PLA2 activity were resolved as proteins of approximately 14,000 Da. The N-terminal sequence obtained from purified peak A material matched that of a recent similar isolate (Hara et al. (1988) J. Biochem. 104, 326-328).

Animals↗
PubMed1989

The proinflammatory effect of intra-articular injection of soluble human and venom phospholipase A2.

The proinflammatory effects of intra-articular injection of purified phospholipase A2 from snake venom and rheumatoid synovial fluid were studied in rats. Purified soluble phospholipase A2 (PLA2) in concentrations ranging from 1000 to 20,000 units/ml, was injected intra-articularly. Histologic parameters examined were cell and protein content of synovial fluid, subsynovial cellular infiltration, synovial lining cell hyperplasia, bone erosion, and peri-articular soft tissue infiltration. Single intra-articular injections of PLA2 resulted in an acute inflammatory infiltrate of the subsynovium with maximal changes seen 2 to 6 hours after injection. Acute inflammatory changes were dose-dependent. Joints injected repeatedly at 24-hour intervals showed prominent synovial lining cell hyperplasia, maximal at 96 hours. Human synovial and snake venom PLA2s were equipotent at inducing both the acute and chronic articular changes. These changes were not seen in joints injected with inactivated PLA2. It is concluded that soluble PLA2 causes time- and dose-dependent acute inflammatory changes after a single intra-articular injection and synovial lining cell hyperplasia in response to repeated exposure to PLA2. The experimental proliferative synovitis in this model may correlate with features of acutely inflammed joints bathed in synovial fluids containing high levels of PLA2 in patients with rheumatoid arthritis.

Animals↗
PubMed1988

Pathogenesis of hypotension in septic shock: correlation of circulating phospholipase A2 levels with circulatory collapse.

Circulating phospholipase A2 (PLA2) has been recognized as a mediator of circulatory collapse in experimental endotoxic shock. To assess the role of serum PLA2 in septic shock in man, we determined serum PLA2 profiles in a prospective study in 12 patients with septic shock. During the hypotensive phase of sepsis, serum PLA2 levels were consistently elevated as high as 33,428 U/ml (normal range 115 +/- 12 [SE]; n = 101). In all 12 patients, PLA2 levels correlated directly with the magnitude and duration of circulatory collapse (p less than .001), with a progressive fall of serum PLA2 levels during convalescence. In contrast, serum PLA2 levels in patients with cardiogenic shock secondary to myocardial infarction remained low. In pancreatitis, PLA2 levels paralleled fluctuations of serum amylase and lipase, whereas in septic shock without pancreatic involvement, PLA2 changes were discordant with changes in pancreatic enzymes. As well, septic shock serum PLA2 failed to crossreact by radioimmunoassay with antiserum against human pancreatic PLA2. These data are consistent with an extrapancreatic source of intravascular PLA2 release during sepsis. Since endogenous serum PLA2 levels correlate directly with the magnitude of hypotension in both experimental endotoxic shock and clinical septic shock, and since parenteral administration of purified exogenous PLA2 reproduces hypotension in experimental models, we conclude that high levels of intravascular PLA2 may contribute similarly to the circulatory collapse in septic shock in man.

Adult↗
PubMed1988

Concordance of endogenous cortisol and phospholipase A2 levels in gram-negative septic shock: a prospective study.

Lipocortins, a group of corticosteroid-induced phospholipase-inhibitory proteins, are thought to play a prominent role in the mediation of the anti-inflammatory effects of steroids. The synthesis and release of these proteins may represent a major endogenous mechanism of regulation of extracellular phospholipase A2 (PLA2) activity. Because soluble PLA2 activity has been associated with circulatory collapse in hyperphospholipasemic conditions, such as septic shock and pancreatitis, we examined the relationship between circulating PLA2 activity and adrenocortical function. In a prospective study of 10 episodes of septic shock, serum PLA2 and cortisol levels correlated significantly in all survivors (p less than 0.0001), whereas such a correlation was absent in all nonsurvivors (p less than 0.07). No significant correlation of cortisol and adrenocorticotropic hormone (ACTH), or PLA2 and ACTH, was found in any patient, suggesting that the stimulus for cortisol release arises from outside the hypothalamic-pituitary axis. These data suggest that, in human beings, the regulation of soluble PLA2 activity may be mediated by adrenocortical hormones, perhaps through the intermediary action of lipocortins.

Adrenocorticotropic Hormone↗
PubMed1988

Phospholipase A2 activity associated with synovial fluid cells.

High activity of phospholipase A2 (PLA2) has been detected in synovial fluids (SF) in inflammatory arthritides. Since the source(s) of SF PLA2 has not been identified, we tested PLA2 content in SF cells obtained from 11 SF. Cell sonicates were prepared at 5 X 10(6) cells/ml. In the supernatants of the sonicated SF cells (n = 11), PLA2 activity ranged from 38-755 U/ml, mean 368 +/- 243 (SD) U/ml, compared to 5-64 U/ml, mean 31 +/- 15 (SD) U/ml in sonicates of normal peripheral blood PMN (n = 5) (p less than 0.0001). Spontaneous release of PLA2 from unstimulated SF cells ranged from 26-365 U/ml, mean 131 +/- 144 (SD) U/ml (n = 5), whereas spontaneous release from peripheral blood PMN was negligible. Neither 10(-8) M FMLP nor 5 X 10(-6) M dexamethasone altered extracellular PLA2 release. To assess whether PLA2 adsorbs passively to cell membranes through hydrophobic interaction, normal peripheral PMN were incubated in crude SF (n = 7) with PLA2 ranging from 4,000-24,300 U/ml, or with purified human SF PLA2 or Naja naja PLA2. We found that soluble PLA2 adsorbed to PMN membranes in a concentration dependent fashion. PLA2 activity in sonicates of PMN incubated in crude SF ranged from 185-358 U/ml compared to controls of 21-64 U/ml. Sonicates of PMN incubated with purified human SF PLA2 (5,000-30,000 U/ml) showed progressive concentration dependent increase in PLA2 from 7 +/- 4 to 212 +/- 11 (SD) U/ml (p less than 0.001). PMN incubated with Naja naja PLA2 also showed marked increase in the content of PLA2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1988

Serum phospholipase A2 correlates with disease activity in rheumatoid arthritis.

We previously demonstrated a marked elevation of the proinflammatory enzyme phospholipase A2 (PLA2) in all synovial fluids and some sera of patients with rheumatoid arthritis (RA). Since PLA2 was found to induce inflammatory changes in the skin and joints of experimental animals, we tested whether the serum level of PLA2 correlates with the clinical activity of RA. In the group of 51 patients with classical or definite RA, 13 (25%) had high serum levels of PLA2 (over 2 standard deviations above the normal mean). Comparison of clinical disease activity in patients with high levels of PLA2 with those with normal PLA2 levels showed that patients with high PLA2 levels had a significantly higher joint count, more swollen joints, much higher Landsbury index, lower functional class, lower hemoglobin, lymphopenia and higher erythrocyte sedimentation rate (ESR). To more accurately assess the relationship between the PLA2 level and disease activity in RA, we formulated 2 indices. Clinical index consisted of the Landsbury index, number of swollen joints and duration of morning stiffness. Laboratory index consisted of hemoglobin, absolute number of peripheral blood lymphocytes, platelet count and ESR. Our results showed that both indices correlated strongly with PLA2 activity (p less than 0.0001). The results support the hypothesis that PLA2 plays a pathogenetic role in RA and suggest that serum PLA2 levels may serve as an additional measure of disease activity.

Adult↗
PubMed1986

Influence of plasma proteins on activity of proinflammatory enzyme phospholipase A2.

The influence of plasma proteins on quantitation of the proinflammatory enzyme phospholipase A2 (PLA2) from rheumatoid synovial fluid was studied using two different assays. Human and bovine serum albumins increased the rate of PLA2 hydrolysis of membrane-associated phospholipid substrates. In contrast, albumin profoundly inhibited the PLA2 hydrolysis of synthetic phospholipids in micellar dispersion. Other plasma proteins (alpha, beta and gamma-globulins) had minimal effect on PLA2 activity in either assay system. Since the presence of albumin may compromise estimation of PLA2 and of phospholipase-inhibitory proteins, the appropriate selection of assay conditions is obligatory for the accurate quantitation of their respective activities.

Arthritis, Rheumatoid↗
PubMed1986

Potential therapeutic efficacy of inhibitors of human phospholipase A2 in septic shock.

Soluble phospholipase A2 has been implicated in the pathogenesis of local and systemic inflammatory reactions. Elevated levels of circulating phospholipase A2 (PLA2) correlate with the severity of circulatory collapse and pulmonary dysfunction in gram-negative septic shock. Characterization of septic shock serum PLA2 revealed a calcium-dependent enzyme with absolute 2-acyl specificity with a pH optimum of 7.5. We tested a number of therapeutic agents for their ability to inhibit PLA2 from human septic shock serum. Chloroquine, chlorpromazine, dexamethasone base, dexamethasone sodium phosphate, indomethacin, lidocaine, oleic acid, palmitic acid, promethazine, trans-retinoic acid, rutin and dl-alpha-tocopherol were all studied over the range of 10(-2) to 10(-7) M. All agents, with the sole exception of dexamethasone base, inhibited PLA2 activity at concentrations greater than 10(-3) M. PLA2 inhibition by dexamethasone sodium phosphate was factitious, due to the formation of calcium-phosphate complexes. Of the 11 agents studied, chlorpromazine was the most effective, with an IC50 of 7.5 X 10(-5) M, a membrane concentration achievable within its therapeutic range. Inhibition was non-competitive with an apparent Ki of 5 nM. Since serum PLA2 levels correlate with mortality in both experimental endotoxemia and clinical gram-negative septic shock, and chlorpromazine was previously shown to improve survival in these conditions, we postulate that its therapeutic efficacy resides at least in part in its PLA2-inhibitory activity.

Dexamethasone↗
PubMed1986

Purification of a soluble phospholipase A2 from synovial fluid in rheumatoid arthritis.

A soluble phospholipase A2 (PLA2) was purified 4,500-fold from human rheumatoid synovial fluid. Preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis yielded two bands of PLA2 activity of molecular weights 15,000 and 17,000 and pl 4.2-5.0. Purified PLA2 had absolute 2-acyl specificity, and hydrolyzed phosphatidylcholine with optimal activity at pH 7.5-8.0 and phosphatidylethanolamine with optimal activity at pH 7.0. Human synovial fluid PLA2 did not cross-react with anti-human pancreatic PLA2, as tested by radioimmunoassay.

Arthritis, Rheumatoid↗
PubMed1986

Inflammatory effect of intradermal administration of soluble phospholipase A2 in rabbits.

Extracellular phospholipase A2 (PLA2) has been found in association with inflamed sites in experimental animals and in humans. The tissue effects of soluble PLA2 have not been defined. We studied the development of inflammatory changes in rabbit skin subsequent to intradermal injection of active and inactivated venom and pancreatic PLA2, over a broad concentration range. PLA2, at concentrations encountered in human disease, caused acute inflammatory changes characterized grossly by erythema and induration, and histologically by inflammatory cell infiltration, vascular and tissue damage, and abscess formation. Extracellular PLA2 may be considered as one of the pathogenic factors in inflammatory reaction.

Acute Disease↗
PubMed1985

Characterization of extracellular phospholipase A2 in rheumatoid synovial fluid.

Phospholipase A2 (PLA2) activity has now been identified in rheumatoid synovial fluids. This PLA2 is a calcium-requiring protein of MW 11,000 with a neutral pH optimum. Its activity was inhibited by high concentrations of Mg2+, and by the active site-directed histidine reagent p-bromophenacyl bromide. Ionic and nonionic detergents, or the sulfhydryl reagent dithiothreitol caused loss of enzyme activity. Synovial fluid PLA2 did not interact with sulphated mucopolysaccharides such as heparin or chondroitin sulphate. Release and sequestration of PLA2 in the joint space may contribute to the characteristic rheumatoid inflammatory changes.

Acetophenones↗
PubMed1985

Phospholipase A2 activity in sera and synovial fluids in rheumatoid arthritis and osteoarthritis. Its possible role as a proinflammatory enzyme.

Phospholipase A2 (PLA2) activity was found in the sera and synovial fluids (SF) in rheumatoid arthritis (RA) and osteoarthritis (OA). PLA2 activity in RA SF was 6158 +/- 549 (SEM) U/ml (n = 48) and in RA sera 554 +/- 175 U/ml (normal sera-115 +/- 12 U/ml). In OA SF PLA2 activity was 5069 +/- 542 U/ml (n = 28), and in OA sera 268 +/- 55 U/ml. There was no significant difference between SF PLA2 activity in RA and OA. PLA2 activity in SF did not correlate with muramidase (lysozyme), beta-glucuronidase, total protein or white cell count, which were all significantly higher in RA SF than OA. A positive correlation between PLA2 in SF and matched sera was found in both RA and OA. It may be concluded that significant elevation of extracellular PLA2 occurs in both RA and OA, especially in the SF. The fact that high PLA2 did not correlate with other enzymes such as lysozyme and beta-glucuronidase, which are usually high in RA and low in OA SF, may mean that the handling of PLA2 in the joint space is different from other enzymes.

Arthritis, Rheumatoid↗
PubMed1984

Benefits of access to on-site acute and critical care for the residential section of a multi-level geriatric center.

Of 220 residents living in the residential unit of a multi-level geriatric center, 95 required a total of 131 transfers to other facilities over a one-year period. Fifty-three of these patients were transferred to the associated chronic-care hospital for short-term acute medical investigation or treatment. The average length of stay of 17 days was similar to that of patients of comparable age with comparable medical conditions admitted to an affiliated acute general hospital from the community. In addition to continuity of medical care and the social and psychologic advantages of remaining within the geriatric center, this transfer potential resulted in substantial financial savings. The cost of hospitalization in the general hospital would have been more than twice that of the geriatric unit.

Aged↗
PubMed1984

Elevated plasma phospholipase A2 levels: correlation with the hemodynamic and pulmonary changes in gram-negative septic shock.

High levels of circulating phospholipase A2 (PLA2) have been implicated in the pathogenesis of hypotension in experimental endotoxin shock. In an attempt to detect similar mechanisms in clinical gram-negative septic shock, plasma samples from 34 patients with hypotension and septicemia were collected and assayed for PLA2 activity. PLA2 levels in 100% of patients with septic shock were elevated (as high as 43-fold over control levels), and mean plasma PLA2 activity was increased 16-fold over control levels. Those patients with concurrent adult respiratory distress syndrome had a mean plasma PLA2 activity level 20.2-fold greater than did controls and 44% greater than patients whose clinical courses were not complicated by adult respiratory distress syndrome. In patients who survived the hypotensive episode, follow-up determinations during the convalescent phase showed a return in plasma PLA2 levels to baseline values. Using pooled plasma, preliminary molecular weight determination revealed the PLA2 to be a 14,000-dalton lipolytic enzyme with 2-acyl specificity. Our study composes the first demonstration of markedly elevated levels of plasma PLA2 during septic shock. Because circulating PLA2 had been shown experimentally to cause profound systemic hypotension and degradation of pulmonary surfactant, this suggests a mechanistic relationship between the massive release of PLA2 into the systemic circulation during the course of gram-negative septicemia, and the resultant hypotension and respiratory distress syndrome associated with gram-negative septic shock.

Adult↗