Protein kinase CK2 activities in human prostatic and seminal-vesicle secretions and seminal plasma

Human prostatic secretion and seminal plasma contain certain protein kinase activities. Protein kinases play important roles in regulating a vast variety of cellular functions. The objective of this study was to determine whether one of these protein kinase activities in human prostatic secretion and seminal plasma is due to CK2, a messenger-independent, serine/threonine protein kinase that has considerable potential as a regulatory enzyme. By employing an anti-CK2 antibody and a CK2-specific peptide substrate, we have established that CK2 is present in these secretions. Approximately 70% of the CK2 activity present in seminal plasma of normozoospermic men (n = 49) is correlated to the number of sperm originally present in the semen. Further, both the prostate gland and the seminal vesicles are sources of CK2 activity in the seminal plasma of vasectomized men (n = 38). Although there was considerable variation between individuals in CK2 activity, the variation in repeat semen samples of the same vasectomized men (n = 6) was within 21%. There was no correlation of CK2 activity in seminal plasma with age for vasectomized (27-48 years, n = 38), oligozoospermic (28-43 years, n = 24), or normozoospermic men (26-48 years, n = 49). These data suggest that the majority of CK2 activity in the seminal plasma of normozoospermic men originates from sperm but that the prostate and seminal vesicles are accessory sex-gland sources of this enzyme.     

The role of repeat transplantation of haemopoietic stem cells and adoptive immunotherapy in treatment of leukaemia relapsing following allogeneic transplantation

Extracellular mobilization of Group IIA 14-kD phospholipase A2 (PLA2) in glycogen-induced rabbit inflammatory peritoneal exudates is responsible for the potent bactericidal activity of the inflammatory fluid toward Staphylococcus aureus (1996. J. Clin. Invest. 97:250-257). Because similar levels of PLA2 are induced in plasma during systemic inflammation, we have tested whether this gives rise to plasma bactericidal activity not present in resting animals. Baboons were injected intravenously (i.v.) with a lethal dose of Escherichia coli and plasma or serum was collected before and at hourly intervals after injection. After infusion of bacteria, PLA2 levels in plasma and serum rose > 100-fold over 24 h to approximately 1 microg PLA2/ml. Serum collected at 24 h possessed potent bactericidal activity toward S. aureus, Streptococcus pyogenes, and encapsulated E. coli not exhibited by serum collected from unchallenged animals. Bactericidal activity toward S. aureus and S. pyogenes was nearly completely blocked by a monoclonal antibody to human Group IIA PLA2 and addition of purified human Group IIA PLA2 to prechallenge serum conferred potent antistaphylococcal and antistreptococcal activity equal to that of the 24 h post-challenge serum. PLA2-dependent bactericidal activity was enhanced approximately 10x by factor(s) present constitutively in serum or plasma. Bactericidal activity toward encapsulated E. coli was accompanied by extensive bacterial phospholipid degradation mediated, at least in part, by the mobilized Group IIA PLA2 but depended on the action of other bactericidal factors in the 24-h serum. These findings further demonstrate the contribution of Group IIA PLA2 to the antibacterial potency of biological fluids and suggest that mobilization of this enzyme during inflammation may play an important role in host defense against invading bacteria.     

Isolation and characterization of a cytosolic phospholipase A2 from bovine adrenal medulla

We have recently demonstrated that bovine adrenal medulla contains a soluble phospholipase A2 (PLA2), which is localized in the cytosol. In the present study, this PLA2 was purified 1,097-fold using sequential concanavalin A, hydrophobic interaction, anion exchange, gel filtration, and an additional anion exchange chromatography. The enzyme is activated over the range of 20-1,000 microM Ca2+ and has a pH optimum near 8.0. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protein has a molecular mass of 26 kDa and an isoelectric point of 4.6 as revealed by isoelectric focusing. The cytosolic PLA2 is not inhibited by NaCl, and the enzymatic activity is stimulated at low concentrations of Triton X-100 (0.01%) and deoxycholate (1 mM) but inhibited at higher concentrations (0.1% and 3 mM, respectively) of these detergents. Furthermore, heat treatment (57 degrees C, 5 min) reduced the enzymatic activity by 80%, whereas glycerol (30%) increased the activity. p-Bromophenacylbromide, a frequently used irreversible inhibitor of type II PLA2, has little effect until 100 microM, and 2-10 mM dithiothreitol totally inactivated the enzyme. The purified PLA2 displays a preference for phosphatidylcholine as a substrate but hydrolyzes phospholipid substrates with arachidonic acid or linoleic acid esterified at the sn-2 position to the same extent. It is concluded that the chromaffin cell cytosolic PLA2, which was isolated and characterized in this study, represents a type of PLA2 that has not been formerly reported in chromaffin cells. Additional research on the chromaffin cell cytosolic PLA2 will help to reveal whether the enzyme is important for exocytosis.     

Neutral alpha-glucosidase, a specific marker for epididymal secretion in seminal pathology]

Semen samples were obtained from 153 patients attending the Centre de recherche en Reproduction Humaine et en Démographie (CRRHD, Bénin) and seminal neutral alpha glucosidase activity was evaluated. Semen contains testicular and accessory gland secretions. Oligozoospernia asthenozoospernia and leucospermia are involved in reducing the fertilizing ability of the spermatozoa. The present work was undertaken to evaluate the variations of seminal alpha glucosidase activity as a specific epididymal enzyme marker in these diseases. A significant positive correlation was demonstrated (P < 0.01) between alpha glucosidase activity and (1) number of spermatozoa in oligozoospermic and normozoospermic men (2) motility of spermatozoa in asthenozoospermic men. No correlation occurred between alpha glucosidase activity and leucospermia. The results of the present study suggest that alpha glucosidase specific activity of the semen was involved in the maturation and acquisition of motility by the germ cells. Otherwise, in our sample, epididymis is scarcely involved in various inflammatory diseases of the reproductive tract.     

A phospholipase A2-related snake venom (from Crotalus durissus terrificus) stimulates neuroendocrine and immune functions: determination of different sites of action

Immune neuroendocrine interactions are vital for the individual's survival in certain physiopathological conditions, such as sepsis and tissular injury. It is known that several animal venoms, such as those from different snakes, are potent neurotoxic compounds and that their main component is a specific phospholipase A type 2 (PLA2). It has been described recently that the venom from Crotalus durissus terrificus [snake venom (SV), in the present study] possesses some cytotoxic effect in different in vitro and in vivo animal models. In the present study, we investigated whether SV and its main component, PLA2 (obtained from the same source), are able to stimulate both immune and neuroendocrine functions in mice, thus characterizing this type of neurotoxic shock. For this purpose, several in vivo and in vitro designs were used to further determine the sites of action of SV-PLA2 on the hypothalamo-pituitary-adrenal (HPA) axis function and on the release of the pathognomonic cytokine, tumor necrosis factor alpha (TNF alpha), of different types of inflammatory stress. Our results indicate that SV (25 microg/animal) and PLA2 (5 microg/animal), from the same origin, stimulate the HPA and immune axes when administered (i.p.) to adult mice; both preparations were able to enhance plasma glucose, ACTH, corticosterone (B), and TNF alpha plasma levels in a time-related fashion. SV was found to activate CRH- and arginine vasopressin-ergic functions in vivo and, in vitro, SV and PLA2 induced a concentration-related (0.05-10 microg/ml) effect on the release of both neuropeptides. SV also was effective in changing anterior pituitary ACTH and adrenal B contents, also in a time-dependent fashion. Direct effects of SV and PLA2 on anterior pituitary ACTH secretion also were found to function in a concentration-related fashion (0.001-1 microg/ml), and the direct corticotropin-releasing activity of PLA2 was additive to those of CRH and arginine vasopressin; the corticotropin-releasing activity of both SV and PLA2 were partially reversed by the specific PLA2 inhibitor, manoalide. On the other hand, neither preparation was able to directly modify spontaneous and ACTH-stimulated adrenal B output. The stimulatory effect of SV and PLA2 on in vivo TNF alpha release was confirmed by in vitro experiments on peripheral mononuclear cells; in fact, both PLA2 (0.001-1 microg/ml) and SV (0.1-10 microg/ml), as well as concavalin A (1-100 microg/ml), were able to stimulate TNF alpha output in the incubation medium. Our results clearly indicate that PLA2-dependent mechanisms are responsible for several symptoms of inflammatory stress induced during neurotoxemia. In fact, we found that this particular PLA2-related SV is able to stimulate both HPA axis and immune functions during the acute phase response of the inflammatory processes.     

Hypersensitivity to chironomid larvae

BACKGROUND: The aim of this study was to identify the proteolytic activity which triggers the transformation of human alpha2-macroglobulin (alpha2-M) in seminal fluid and its binding to its receptor. METHODS: Measurement of the concentrations of total and transformed alpha2-M in seminal fluid was accomplished by ELISA. Zymography of seminal plasma was performed in SDS-polyacrylamide gels containing casein as proteolytic substrate. Rate electrophoresis, SDS-PAGE, and Western blotting were applied to study the complex formation of prostate-specific antigen (PSA) with alpha-M. Ligand-binding analysis of sperm cells was performed using [125I] labeled proteins. Detection of receptor on sperm cells was achieved by immunofluorescence. RESULTS: The mean concentration of total alpha2-M in a random collection of seminal plasma was 4.6 microg/ml. On average, between 33-98% of the inhibitor was found to be transformed. Zymography of seminal plasma revealed a proteolytic activity which is associated with a 33-kDa protein identified as PSA. Its proteolytic activity could be inhibited by 0.2-M. Both purified PSA and seminal plasma were capable of transforming native alpha2-M. Binding of PSA to alpha2-M triggers the exposition of receptor binding sites in the inhibitor molecule, which causes binding of the complex to alpha2-M-R/LRP identified on spermatozoa. CONCLUSIONS: PSA, the main proteinase in seminal fluid, is responsible for the transformation of alpha2-M and for its binding to alpha2-M-R/LRP present on spermatozoa. The binding of alpha2-M-PSA complexes to the spermatozoa receptor may exert an impact on normal sperm-cell functions.     

Inhibition of Trimeresurus flavoviridis phospholipase A2 by lung surfactant protein A (SP-A)

A marked sequence homology has been noted between lung surfactant protein A (SP-A) and an inhibitor of phospholipase A2 (PLA2) isolated from the serum of Trimeresurus flavoviridis (Habu snake). This study evaluated the effect of SP-A on PLA2 activity from several sources. SP-A was isolated from bovine or rat lung surfactant by extraction with 1-butanol and octyl beta-D-glucopyranoside. The addition of SP-A produced a concentration-dependent inhibition of T. flavoviridis PLA2 that indicated non-competitive kinetics with Ki 5 micrograms/ml. Inhibition was reversed by heat inactivation, disulfide bond reduction or alkylation of SP-A, or by the presence of anti-SP-A antibody. Treatment of SP-A with endoglycosidase F or the presence of variation monosaccharides or lectins did not alter SP-A inhibition. Binding of PLA2 to SP-A was shown by ultrafiltration and was abolished by SP-A alkylation or the presence of SDS. The SP-A/PLA2 complex recovered from the ultrafilter had essentially no enzymatic activity, but activity was restored by treatment with mercaptoethanol. SP-A had no effect on activity of PLA2 from Naja naja, Crotalus atrox, or bovine pancreas. These results indicate that surfactant protein A selectively inhibits Trimeresurus phospholipase A2 activity and suggest that binding to the enzyme is the mechanism for inhibition.     

Follistatin and activin A production by the male reproductive tract

Follistatin is a binding protein for the activin and inhibin family of hormones, regulating their biological activity. In the male reproductive tract, the interaction of these factors is likely to be involved in the regulation of the proliferation of several cell types. We have investigated the presence of follistatin and activin A in seminal plasma using specific immunoassays and have localized follistatin and activin/inhibin subunits in the adult human testis, prostate and seminal vesicle to establish their likely sources. High concentrations of immunoreactive follistatin were present in seminal plasma in normal men (mean 97.9 ng/ml; 1.43 ng/ml in peripheral plasma) and were similar in men with oligo/azoospermia and following vasectomy. Follistatin immunoreactivity was localized to both Leydig and Sertoli cells of the testis, and to epithelial cells of the prostate gland and seminal vesicle, which are likely to be the predominant sources of the hormone in seminal plasma. Activin A was also present in seminal plasma in normal men but was undetectable following vasectomy, thus deriving from the testis. Consistent with this finding, the betaA-subunit was immunolocalized in Sertoli and Leydig cells but was not present in seminal vesicle or prostate gland. The functional significance of the high concentrations of follistatin secreted into seminal plasma by the prostate gland and/or seminal vesicle is uncertain, but they may regulate the biological activity of testis-derived activin A and inhibin B.     

Prostate specific origin of dipeptidylpeptidase IV (CD-26) in human seminal plasma

PURPOSE: A number of peptidases which can metabolize certain bioactive peptides and growth factors have been identified in seminal plasma. Our goal in this study was to determine molecular properties and the tissue source(s) for one of these peptidases, dipeptidylpeptidase IV (DPP IV), in human seminal plasma. MATERIALS AND METHODS: We measured the activities of DPP IV with the dipeptide glycylprolyl-p-nitroanalide and its molecular forms using immunoblotting of seminal plasmas of men who were vasectomized or with different sperm concentrations, and in prostatic and seminal vesicle secretions of men undergoing prostatic surgery. RESULTS: DPP IV in seminal plasma of vasectomized men was a membrane associated dimer comprised of subunits of approximately 110 kDa. Its activity did not differ in seminal plasmas of vasectomized, azoospermic, oligozoospermic and normozoospermic men indicating no correlation with the concentration of sperm originally present in the semen. The DPP IV antigen (CD -26) and enzymic activity were present in prostatic secretion, but absent from that of the seminal vesicles. These data indicate that the prostate gland is the primary source of DPP IV activity in seminal plasma. There was little variation in its activities in repeat seminal plasma samples from the same individual, and there was no change in its activity with age to 50 years. CONCLUSIONS: DPP IV in seminal plasma was derived from the prostate gland and it may be useful as a bioindicator of prostate function and/or disease with age in men.     

Simultaneous determinations of pancreatic phospholipase A2 and prophospholipase A2 in various pancreatic diseases

Pancreatic phospholipase A2 (PLA2) is secreted into the pancreatic juice by pancreatic acinar cells as a proenzyme (proPLA2), which is activated by trypsin. Radioimmunoassays with monoclonal antibodies to PLA2 and proPLA2 were used to examine the serum PLA2 and proPLA2 levels simultaneously in patients with various pancreatic diseases. In healthy subjects, proPLA2 proved to be the major form of the enzyme. The serum PLA2 level were found to be significantly increased in patients with acute pancreatitis, the active phase of chronic relapsing pancreatitis, and the early stage of pancreatic cancer. In the terminal stage of pancreatic cancer the serum PLA2 level became low. In patients with chronic pancreatitis, significant correlations were observed between the levels of factors evaluated by the secretin test and the serum total PLA2 and proPLA2 level, but not the PLA2 level. The serum PLA2 and proPLA2 concentrations, and the proportion of proPLA2 in the total, were within normal ranges in patients with liver cirrhosis, hepatocellular carcinoma, and chronic renal failure. These results suggest that simultaneous measurements of serum PLA2 and proPLA2 are clinically useful for diagnosis and monitoring of the active phase of pancreatitis.     

Plasma membrane phospholipid asymmetry precedes DNA fragmentation in different apoptotic cell models

Enhancing factor (EF) protein was initially purified as a modulator of epidermal growth factor from small intestines of mouse. The cDNA sequence, obtained by RT-PCR, revealed that EF belonged to the non-pancreatic, phospholipase A2 (PLA2) family. This was the first report of the mouse PLA2. In the present paper we report the complete cDNA sequence of EF gene, in which the 5' sequence has been obtained by RAcE-PCR. The predicted amino acid sequence was computer analysed and the putative sites for enzyme action, calcium binding and heparin binding have been identified. The complete protein sequence of EF along with 16 aligned sequences were used to infer a phylogenetic tree. From this data the mouse EF was grouped with other membrane associated PLA2 with a bootstrap value of 98% indicating that it belonged to this class.     

PLA2 activity regulates Ca2+ storage-dependent cellular proliferation

The objective of this study is to determine the role of arachidonic acid (AA) in cell proliferation by inhibiting AA synthetic enzyme phospholipase A2 (PLA2) and to determine its involvement in the role of the second messenger intracellular calcium (Ca2+). Methods used to determine the effects on proliferation of cell cultures of primary meningioma and astrocytoma U373-MG included treatment with micromolar concentrations of PLA2 inhibitors 4-bromophenacylbromide and quinacrine. Effects of these drugs on proliferation were further investigated by the application of concentrations that inhibit growth by 50% while antagonizing these agents with AA replacement. Free cytosolic Ca2+ was measured with the use of fluorescent dye Fura-2 during PLA2 agonist/antagonist studies. These Ca2+ measurements were performed in the absence of extracellular Ca2+ to identify the contribution of intracellular Ca2+ sources. PLA2 inhibition resulted in decreased growth of cultured astrocytoma and meningioma cells in a dose-dependent manner in the micromolar range. This inhibitory effect was antagonized by the addition of AA. PLA2 inhibition caused an elevation of basal-cytosolic-free [Ca2+] while depleting internal Ca2+ stores. These Ca2+ changes were also antagonized by the addition of AA. In conclusion, these results demonstrate that AA, a PLA2 enzyme product, is involved in regulating the growth rate of these cell types. The PLA2 pathway also regulates the maintenance of the internal Ca2+ stores. Ca2+ is known to be a growth-related intracellular second messenger. These results suggest that the growth regulatory functions of AA are mediated by Ca2+-dependent mechanisms.     

Phospholipase A2 action on planar lipid bilayers generates a small, transitory current that is voltage independent

Addition of either bee venom or Trimeresurus flavoviridis phospholipase A2 (PLA2) to the solution bathing the front side of a voltage-clamped, planar lipid bilayer consistently produced a transitory current lasting approximately 100 s. This current is consistent with anions moving through the membrane to the rear side. The peak current is independent of holding potential. PLA2 activity on phospholipid membranes not only produced a current but also led to membrane rupture within 300 s. The current depends on Ca2+ and lipid type. Addition of PLA2 in the absence of Ca2+ or to membranes made of nonsubstrate lipids (e.g., glycerol monooleate or lysophosphatidylcholine) produced no current and did not break the bilayer. Peak current height, signal decay time, and time to membrane rupture all depended on PLA2 dose, whereas total charge produced was constant. This current does not flow through ion channels because there are no channels present and the current is not voltage dependent. The evidence is consistent with the hypothesis that the current is generated by the movement of ionized fatty acid produced by PLA2 action. These results demonstrate a simple method to measure enzyme activity in the presence of different substrates and varied environmental conditions.     

Possible involvement of mitogen-activated protein kinase in phospholipase D activation induced by H2O2, but not by carbachol, in rat pheochromocytoma PC12 cells

We have previously reported that hydrogen peroxide (H2O2) induced a considerable increase of phospholipase D (PLD) activity and phosphorylation of mitogen-activated protein (MAP) kinase in PC12 cells. H2O2-induced PLD activation and MAP kinase phosphorylation were dose-dependently inhibited by a specific MAP kinase kinase inhibitor, PD 098059. In contrast, carbachol-mediated PLD activation was not inhibited by the PD 098059 pretreatment whereas MAP kinase phosphorylation was prevented. These findings indicated that MAP kinase is implicated in the PLD activation induced by H2O2, but not by carbachol. In the present study, H2O2 also caused a marked release of oleic acid (OA) from membrane phospholipids in PC12 cells. As we have previously shown that OA stimulates PLD activity in PC12 cells, the mechanism of H2O2-induced fatty acid liberation and its relation to PLD activation were investigated. Pretreatment of the cells with methylarachidonyl fluorophosphonate (MAFP), a phospholipase A2 (PLA2) inhibitor, almost completely prevented the release of [3H]OA by H2O2 treatment. From the preferential release of OA and sensitivity to other PLA2 inhibitors, the involvement of a Ca2+-independent cytosolic PLA2-type enzyme was suggested. In contrast to OA release, MAFP did not inhibit PLD activation by H2O2. The inhibitory profile of the OA release by PD 098059 did not show any correlation with that of MAP kinase. These results lead us to suggest that H2O2-induced PLD activation may be mediated by MAP kinase and also that H2O2-mediated OA release, which would be catalyzed by a Ca2+-independent cytosolic PLA2-like enzyme, is not linked to the PLD activation in PC12 cells.     

Altered arachidonic acid metabolism contributes to the failure of dopamine to inhibit Na+,K(+)-ATPase in kidney of spontaneously hypertensive rats

Dopamine decreases tubular sodium reabsorption in part by inhibition of Na+,K(+)-ATPase activity in renal proximal tubules. The signaling mechanism involved in dopamine-mediated inhibition of Na+,K(+)-ATPase is known to be defective in spontaneously hypertensive animals. The present study was designed to evaluate the role of phospholipase A2 (PLA2) and its metabolic pathway in dopamine-induced inhibition of Na+,K(+)-ATPase in renal proximal tubules from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). Renal proximal tubular suspensions were prepared and Na+,K(+)-ATPase activity was measured as ouabain-sensitive adenosine triphosphate hydrolysis. Dopamine inhibited Na+,K(+)-ATPase activity in a concentration (1 nM-10 microM)-dependent manner in WKY rats while it failed to inhibit the enzyme activity in SHR. Dopamine (10 microM)-induced inhibition of Na+,K(+)-ATPase activity in WKY rats was significantly blocked by mepacrine (10 microM), a PLA2 inhibitor, suggesting the involvement of PLA2 in dopamine-mediated inhibition of Na+,K(+)-ATPase. Arachidonic acid (a product released by PLA2 action) inhibited Na+,K(+)-ATPase in a concentration-dependent (1-100 microM) manner in WKY rats while the inhibition in SHR was significantly attenuated (IC50: 7.5 and 80 microM in WKY rats and SHR, respectively). Furthermore, lower concentrations of arachidonic acid stimulated (30% at 1 microM) Na+,K(+)-ATPase activity in SHR. This suggests a defect in the metabolism of arachidonic acid in SHR. Proadifen (10 microM), an inhibitor of cytochrome P-450 monoxygenase (an arachidonic acid metabolizing enzyme) significantly blocked the inhibition produced by arachidonic acid in WKY rats and abolished the difference in arachidonic acid inhibition of Na+,K(+)-ATPase between WKY rats and SHR. These data suggest that PLA2 is involved in dopamine-induced inhibition of Na+,K(+)-ATPase and altered arachidonic acid metabolism may contribute to reduced dopaminergic inhibition of Na+,K(+)-ATPase activity in spontaneously hypertensive rats.     

Regionalization and redistribution of membrane phospholipids and cholesterol in mouse spermatozoa during in vitro capacitation

Fracture-label, surface-replica, and routine freeze-fracture techniques were used in combination with phospholipase A2-colloidal gold (PLA2-CG) and filipin as probes to study changes in the distribution of phospholipids and cholesterol, respectively, in morphologically defined plasma membrane domains of mouse spermatozoa during in vitro capacitation. In noncapacitated spermatozoa, quantitative analysis revealed that the fractured plasma membrane overlying the equatorial segment carried the highest PLA2-CG labeling density. The next highest labeling densities were found in the anterior acrosome region and the post-acrosomal region. On the external surface of the plasma membrane revealed by surface replicas, a uniform distribution of PLA2-CG was confined mainly to the acrosomal region of the head. The plasma membrane of the sperm tail had a relatively low labeling density for PLA2-CG. In freeze-fracture replicas of filipin-treated spermatozoa, the labeling density of filipin/sterol complexes (FSCs) was high in the plasma membrane over the acrosomal region where the FSCs were uniformly distributed. The postacrosomal region was weakly labeled. After in vitro capacitation, the densities of PLA2-CG and FSCs were significantly reduced in the fractured plasma membrane of the sperm head and the middle piece of the tail. However, surface replicas revealed an increased PLA2-CG labeling on the external surface of the plasma membrane covering the postacrosomal region, the middle piece, and the principal piece. Another major change detected in capacitated spermatozoa was the presence of small aggregates and patches of elevated, membrane-associated particles on the surface-replicated plasma membrane in the upper portion of the postacrosomal domain. Here the PLA2-CG labeling density was found to be higher than in noncapacitated spermatozoa. These results provide new information with respect to the reorganization and redistribution of phospholipids in specific regions of the plasma membrane during capacitation and provide further support for the concept that removal or loss of antifusigenic sterol from the sperm plasma membrane constitutes an important step of the capacitation process.     

Relationships between plasma levels of type-II phospholipase A2, PAF-acetylhydrolase, leukotriene B4, complements, endothelin-1, and thrombomodulin in patients with sepsis

We determined the plasma levels of type-II phospholipase A2 (type II PLA2), platelet-activating factor acetylhydrolase (PAFAH) leukotriene B4 (LTB4) and of several complements (C3a, C4a, and C5a), which are considered to be among the cytokines and eicosanoids involved in vascular endothelial disorders and that vary in concentration during sepsis. We investigated the relationship between those levels and those of ET-1 and TM levels in plasma. Plasma levels of type II PLA2, PAFAH, LTB4, C3a, C4a, ET-1, and TM at the time that sepsis was diagnosed in 30 patients were 218.3 +/- 179.9 ng/ml, 23.92 +/- 9.66 nmol/min/ml, 90.35 +/- 31.49 pg/ml, 838.73 +/- 2.30 pg/ml, 1951.46 +/- 1697.78 pg/ml, 6.98 +/- 4.08 pg/ml and 7.80 +/- 3.34 ng/ml, respectively. The C5a plasma level was below the limit of detection in all cases. There were significant correlations between type II PLA2 and ET-1 plasma levels (r = 0.39, p = 0.032) and C3a and ET-1 plasma levels (r = 0.60, p = 0.03). There were also significant correlations between type II PLA2 and TM levels in plasma (r = 0.76, p = 0.0017), PAFAH and TM plasma levels (r = 0.53, p = 0.037), LTB4 and TM plasma levels (r = 0.46, p = 0.016) and C4a and TM plasma levels (r = 0.58, p = 0.037). Results suggest that the elevation of type II PLA2, PAFAH, LTB4 and complement in plasma is involved in vascular endothelial disorders in patients with sepsis.     

Activation of arachidonic acid-specific phospholipase A2 in human neuroblastoma cells after chronic alcohol exposure: prevention by GM1 ganglioside

Human neuroblastoma cells were exposed to ethanol (EtOH; 100 mM) in culture for various time periods. It was found that chronic EtOH exposure increased the arachidonyl-specific phospholipase A2 (PLA2) activity significantly in both cytosol (1.6-fold) and membrane (2.2-fold) fractions when 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine was used as a substrate. This arachidonyl-specific PLA2 activity progressively increased with increasing duration of EtOH exposure and reached peak level at 72-hr EtOH exposure (chronic). A significant amount of the PLA2 activity was associated with the membrane fraction. No significant difference in PLA2 activity was observed when 1-palmitoyl-2 oleoyl or linoleoyl-sn-glycero-3-phosphocholine was used as a substrate. It was also found that co-treatment of neuroblastoma cells with ganglioside GM1 reduced the EtOH-induced activation of arachidonyl-specific PLA2 activity. The present results indicate that arachidonic acid-specific PLA2 may play a role in adaptation mechanisms to chronic EtOH in cultured neuroblastoma cells. Ganglioside GM1, in part, may exert its neuroprotective effects by modulating arachidonyl-specific PLA2 activity in chronic EtOH-exposed neuroblastoma cells.     

Detection of antisperm antibodies in seminal plasma by flow cytometry: comparison with the indirect immunobead binding test

OBJECTIVE: To compare flow cytometry with the established indirect immunobead binding test (IBT) for the detection of antisperm antibodies in seminal plasma. DESIGN: A prospective, comparative study. SETTING: University-based andrology unit. PATIENT(S): One hundred and fifty-eight men with suspected male factor subfertility. INTERVENTION(S): Seminal plasma samples were incubated with antisperm antibody-negative donor sperm. Surface-bound antibody was detected with fluorescence-labeled antihuman antibody in the flow cytometry assay or with immunobead-labeled antihuman antibody in the IBT. MAIN OUTCOME MEASURE(S): The percentage of sperm that tested positive for surface-bound antibody was determined in the two assays. Seminal plasma was antisperm antibody-positive when > or = 20% of the sperm were antibody-bound, and clinically significant levels were present when > or = 50% of the sperm were antibody-bound. RESULT(S): Of 71 samples that were negative by the IMT, 66 (93%) also were negative by flow cytometry. Of 63 samples that had > or = 50% immunobead binding, 55 had equivalent results by flow cytometry. Overall statistical analysis showed a good correlation between the two assays. CONCLUSION(S): There is a good correlation between the indirect IBT and indirect flow cytometry for the detection of antisperm antibodies in seminal plasma.     

Inhibition of the oxidative metabolism of human spermatozoa by a heat-labile factor in seminal plasma

The effect of different media on the oxidative and glycolytic metabolism and on the motility of human spermatozoa has been investigated. Sperm resuspended in Ringer's solution produce more carbon dioxide than sperm in the original seminal plasma. In addition, sperm resuspended in heated seminal plasma have a higher carbon dioxide production and higher oxygen uptake than sperm in untreated seminal plasma. The mean lactic acid production was not significantly affected by different media. The motility of sperm in heated seminal plasma was poorer than that in untreated seminal plasma, although the percentage of cells that stained with eosin did not differ in the two media. After being heated, seminal plasma not only continued to take up oxygen but did so at a higher rate. The results of the present study suggest that seminal plasma contains a heat-labile component that inhibits the oxidative metabolism of human sperm but does not significantly alter sperm glycolysis.