Platelet-activating Factor Content Research Articles

Impacts of high-voltage electrical burn on serum platelet-related factors and platelet aggregation number in rats and the interventive effect of Xuebijing

Objective: To explore the effect of high-voltage electrical burn on platelet function and rheological behavior in rats and the interventive effect of Xuebijing. Methods: A total of 280 Sprague Dawley rats of clean grade (aged 8-10 weeks, male and female unlimited) were divided into sham injury group, simple electrical burn group, electrical burn+ saline group, and electrical burn+ Xuebijing group according to the random number table, with 70 rats in each group. Rats in sham injury group were not conducted with electrical current to cause sham injury. Rats in the other three groups were given electrical current with output voltage of 2 kV and current intensity of (1.92 ± 0.24) A for 3 s, which caused high-voltage electrical burn wounds, each with an area of 1 cm×1 cm distributed in the left forelimb at the current inlet and the right hindlimb at the current outlet respectively. Rats in sham injury group and simple electrical burn group were not treated after injury. At post injury minute 2 and on post injury day (PID) 1, 2, 3, 4, 5, and 6, rats in electrical burn+ saline group and electrical burn+ Xuebijing group were intraperitoneally injected with 6 mL/kg saline and 6 mL/kg Xuebijing, respectively. Survival conditions of rats were recorded during the experiment. At 15 min before injury and at post injury hour (PIH) 1, 8, 24, 48, 72, and on PID 7, 10 rats in each group were respectively selected according to the random number table to sacrifice after collection of 5 mL blood under the direct vision of heart. Blood in the volume of 0.05 mL from each rat was taken to make blood smear, and platelet aggregation number was counted under 400 fold field of view using multiple projection microscope. The remaining blood samples were centrifuged to collect supernatant, and the content of platelet-derived growth factor (PDGF), thrombopoietin (TPO), and platelet activating factor (PAF) was detected by enzyme-linked immunosorbent assay. Data were statistically analyzed with analysis of variance for factorial design and Student-Newman-Keuls method. Results: All rats in sham injury group and simple electrical burn group survived during the experiment. One rat in electrical burn+ saline group died on PID 6, and one rat on PID 5 and one rat on PID 6 died in electrical burn+ Xuebijing group. The levels of all indexes among the 4 groups were close at 15 min before injury. The serum content of PDGF, TPO, and PAF and platelet aggregation number of rats in the three electrical burn groups at all time points after injury were higher or more than those in sham injury group, and the first three indexes reached the peak at PIH 8. The serum platelet aggregation number of rats in simple electrical burn group reached the peak at PIH 48, and that in electrical burn+ saline group and electrical burn+ Xuebijing group reached the peak at PIH 72. Among them, the serum content of PDGF of rats in electrical burn+ Xuebijing group at PIH 48, 72 and on PID 7 ((12.8±4.0), (11.6±4.4), (11.0±3.6) ng/mL, respectively) was close to that in sham injury group ((10.4±2.0), (10.4±2.5), (9.8±3.3) ng/mL, respectively, P>0.05). The serum content of TPO of rats in electrical burn+ Xuebijing group at PIH 24, 72 and on PID 7 ((200±52), (192±36), (193±32) ng/mL, respectively) was close to that in sham injury group ((182±30) , (184±41), (183±33) ng/mL, respectively, P>0.05). The serum content of PDGF, TPO, and PAF and platelet aggregation number of rats in electrical burn+ Xuebijing group at every time point after injury was generally lower or less than that in electrical burn+ saline group and simple electrical burn group. Conclusions: Application of Xuebijing treatment after high-voltage electrical burn can decrease the content of PDGF, TPO, and PAF in the serum and reduce the number of platelet aggregation, thereby inhibit platelet activation and improve platelet rheology.

Exposure to Cigarette Smoke is Linked to Platelet‐Activating Factor Accumulation in Myocardial Tissue

Smoking is a lifestyle risk factor for heart disease and is responsible for one‐third of all cardiovascular deaths. Although many studies have investigated the correlation between smoking and coronary artery disease, there are few studies examining the direct effect of smoking on the myocardium. In this study, we examined the effect of smoking on myocardial accumulation of platelet‐activating factor (PAF), a phospholipid mediator that causes a negative inotropic effect, arrhythmias, apoptosis and is involved in inflammation and atherosclerosis. Ventricular samples from mice exposed up to six months of cigarette smoke (48 min/day, 5 days/week), and human right atrial samples from smokers and nonsmokers scheduled for coronary artery bypass graft surgery were analyzed for biochemical and histochemical changes using activity assays, ELISA, immunoblot, and immunohistochemistry. Mice exposed to cigarette smoke showed a decrease in PAF‐acetylhydrolase (PAF‐AH, the enzyme responsible for PAF metabolism) activity that was significant after 1 month and decreased progressively over the 6 month period (5.8 ± 0.3 to 3.2 ± 0.5 nmol/mg protein/min, p<0.01, n=6). This inhibition in PAF‐AH activity was accompanied by increased myocardial PAF content (0.23 ± 0.04 to 0.35 ± 0.03 at 6 months smoking, p<0.05, n=6). In humans, smoking was associated with an increase in PAF content (3.19 ± 0.28 vs 4.29 ± 0.37 nmol/mg protein, p<0.05, n=18) and inhibition of PAF‐AH activity (30.7 ± 2.0 vs 23.2 ± 1.8 nmol/mg protein/min, p<0.01, n=18) when comparing atrial tissue from never smokers to current smokers. We did not detect a change in phospholipase A2 activity (the enzyme responsible for PAF production) in human or mouse myocardium exposed to cigarette smoke or room air. Thus, we hypothesize that the increase in PAF content in the myocardium is likely a result of smoking‐induced inhibition of PAF‐AH activity. The inhibition of PAF‐AH and subsequent accumulation of PAF in the myocardium of cigarette smokers may play a role in the pathogenesis of heart disease in this population.Support or Funding InformationLottie Caroline Hardy Foundation (to J.McH.)

Urinary Platelet‐Activating Factor as an Indicator of Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic inflammatory bladder disease with multiple etiological contributors and risk factors associated with its development, including cigarette smoking. In a recently published manuscript, we have shown that smoking is associated with bladder wall inflammation and accumulation of platelet activating factor (PAF), a potent inflammatory mediator that facilitates transendothelial inflammatory cell migration and reduction in tight junction protein expression, which could contribute to urothelial cell dysfunction. PAF accumulation in response to cigarette smoking is primarily the result of the inhibition of PAF acetylhydrolase (PAF‐AH, the enzyme responsible for PAF hydrolysis and inactivation). The present study was designed to determine whether urine content of PAF or PAF‐AH activity can be used as an indicator of IC/BPS. For stability studies, voided urine specimens were collected from patients with and without a diagnosis of IC/BPS. Samples were stored at room temperature and frozen in liquid nitrogen at intervals up to 60 mins following voiding. PAF content and PAF‐AH activity were measured and normalized to creatinine. Measurement of PAF and PAF‐AH was consistent at all time intervals up to 60 mins, demonstrating stability following voiding. Addition of PAF internal standard to urine samples prior to analysis indicated a recovery of >96% PAF. PAF content in the urine of IC/BPS patients (1.16 ± 0.16 PAF:creatinine ratio, n=6, p<0.05) was significantly greater than that for non‐IC/BPS patients (0.37 ± 0.18 PAF:creatinine ratio, n=5). PAF content was also greater in IC/BPS patients who smoke (1.19 + 0.36 PAF:creatinine ratio, n=4, p<0.05) when compared to non‐IC/BPS patients. PAF‐AH activity was decreased in the urine of IC/BPS patients who were smokers (48.3 ± 2.4 PAF‐AH: creatinine ratio, n=4, p<0.05) or non‐smokers (40.0 ± 7.0 PAF‐AH: creatinine ratio, n=6, p<0.05) when compared to non‐smokers with no IC/BPS (64.6 ± 2.2 PAF‐AH:creatinine ratio, n=5). Our data demonstrate that urine content of PAF and/or PAF‐AH is stable at up to 60 mins storage at room temperature following voiding. Urinary PAF is increased in IC/BPS patients, and is likely the result of PAF‐AH inhibition. Future studies are required to determine the effect of cigarette smoking on the incidence and severity of IC/BPS.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effects of senna and its active compounds rhein and rhein-anthrone on PAF formation by rat colon.

A single or a prolonged oral administration of senna (60 mg kg-1) to rats did not increase either colonic PAF (platelet activating factor) content or intraluminal release of acid phosphatase. A similar result was observed in the colonic tissue of rats perfused in-vitro with rhein (1-300 micrograms mL-1) or rhein-anthrone (1-300 micrograms mL-1). A single or prolonged administration of castor oil (2 mL) to rats increased both colonic PAF content and intraluminal release of acid phosphatase. Colonic tissue of rats perfused in-vitro with calcium ionophore A23187 (1 and 10 micrograms mL-1) formed large amounts of PAF and acid phosphatase. Since PAF can mediate intestinal damage and acid phosphatase is a marker of cellular injury, we conclude that senna and its derivatives, rhein and rhein-anthrone, are well tolerated in rats.

Relationship between in vitro sperm functional tests and in vivo fertility of rams following cervical artificial insemination of ewes with frozen-thawed semen

Several procedures have been proposed to assess structural and functional characteristics of cryopreserved ram semen but none so far have yielded consistent relationships with in vivo fertility. The objectives of this study were to evaluate several sperm function tests as potential markers of in vivo ram fertility (determined by pregnancy rate in ewes) using frozen-thawed semen. In experiment 1, frozen-thawed straws ( n = 3 per ram) of semen from three high and three low fertility rams were assessed using fluorescent microscopy for (1) progressive motility, (2) viability and, (3) acrosomal status. In experiment 2, frozen-thawed straws ( n = 3 per ram) of semen from 18 rams of known fertility were analysed using either computer-assisted sperm analysis (CASA) for eight motion characteristics or flow cytometric staining for: (1) viability and acrosomal status, (2) plasma membrane status and capacitation-like changes, and (3) live cells following an osmotic resistance test (ORT). In experiment 3, platelet-activating factor (PAF) was isolated from straws ( n = 2 per ram) of semen using high-pressure liquid chromatography (HPLC) and quantified using HPLC–tandem mass spectrometry for 18 rams. In experiment 1, no association was found between motility, viability (% live) or acrosomal status (% damaged, % intact and % reacted) and in vivo fertility. In experiment 2, no correlation was found between motility (CASA), viability (% live), acrosomal status (% live, % live intact and % reacted), capacitation status (% capacitated, % non-capacitated), plasma membrane stability (% dead) and % live cells following ORT and ram in vivo fertility. In experiment 3, there was no relationship between PAF content in spermatozoa and ram fertility. In conclusion, we were unable to relate the in vivo fertility of rams with in vitro functional tests of their frozen-thawed semen and suggest that the fertility of a given semen sample cannot easily be quantified using available in vitro tests.

DIETARY GANGLIOSIDE INHIBITS ACUTE INFLAMMATORY SIGNALS IN INTESTINAL MUCOSA AND BLOOD INDUCED BY SYSTEMIC INFLAMMATION OF ESCHERICHIA COLI LIPOPOLYSACCHARIDE

Our previous study demonstrated that feeding ganglioside increased total ganglioside content while decreasing cholesterol and caveolin-1 content in developing rat intestinal lipid microdomains. Cholesterol or caveolin depletion in membranes inhibits inflammatory signaling by disrupting microdomain structure. We hypothesized that dietary ganglioside-induced reduction in cholesterol content will reduce proinflammatory mediators in the intestinal mucosa after acute exposure to bacterial endotoxin. Weanling rats were fed semipurified diets with 0.1% (wt/wt of total fat) gangliosides (treatment) or without ganglioside (control). After 2 weeks of feeding, half of animals from each diet group were injected with saline or lipopolysaccharide (LPS) endotoxin (Escherichia coli serotype O111:B4, intraperitoneal, 3 mg/kg body weight) to induce acute gut inflammation. Intestinal mucosa and blood were collected after 6 h. The effect of dietary ganglioside on proinflammatory mediators including cholesterol, platelet-activating factor, prostaglandin E2, leukotriene B4 (LTB4), interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNF-alpha) was determined in inflamed mucosa and blood. Feeding animals the control diet increased cholesterol content in intestinal lipid microdomains by 92% after LPS injection compared with saline injection. Animals fed the ganglioside diet significantly decreased cholesterol content in lipid microdomains by 60% compared with animals fed the control diet. Feeding animals the ganglioside diet increased total ganglioside content by 90% while decreasing platelet-activating factor content by 45% in the inflamed mucosa by acute systemic exposure to LPS compared with animals fed the control diet. When animals were fed the ganglioside diet, the levels of prostaglandin E2, LTB4, IL-1beta, and TNF-alpha were lower in inflamed mucosa, and LTB4, IL-1beta, and TNF-alpha were decreased in plasma by 41%, 58%, and 55% compared with control animals, respectively. The present study demonstrates that dietary gangliosides inhibit proinflammatory signals in the intestine and blood induced by acute inflammation of LPS and suggests therapeutic potential in the treatment and management of acute local and systemic inflammatory diseases.

Influence of the Preimplantation Embryo Development (Ped) Gene on Embryonic Platelet-Activating Factor (PAF) Levels

A major gene responsible for the control of preimplantation cleavage rate is the Ped gene, the product of which is the Qa-2 protein. Fast, but not slow developing mouse embryos express the Qa-2 protein. Platelet-activating factor (PAF) is a novel and potent signaling phospholipid that has unique pleiotropic properties in addition to platelet activation. PAF plays a significant role in virtually every reproductive event, including ovulation, fertilization, implantation, and parturition. The role of the Ped gene in PAF production by preimplantation embryos is yet to be established. The presence of this gene provides embryos with a reproductive advantage over those that are Ped negative, and may also serve as a regulator of PAF synthesis. The study hypothesis is that the amount of PAF produced is dependent upon the presence or absence of the Ped gene. B6.K1 (Ped negative) and B6.K2 (Ped positive) mouse embryo-conditioned culture media were assayed for PAF content by a PAF-specific radioimmunoassay. There was a significant (p < 0.001) difference in blastocyst development rates between the Ped+ B6.K2 (61.0%) and the Ped- B6.K1 (25.3%) embryo culture groups. There was a significant difference (p < 0.05) in PAF production between the Ped+ B6.K2 (4.70+/-0.46 pmol per embryo) embryo culture group and the Ped- B6.K1 (10.02+/-3.49 pmol per embryo) embryo group. The B6.K1 (Ped-) embryo group produced >2x more PAF than did the B6.K2 (Ped+) group. The Ped gene plays a role in PAF production and release in preimplantation stage embryos. The use of two mouse identical strains, except for the Ped gene, show that its presence is associated with an increase in developmental potential. Embryos where the Ped gene was absent produced significantly higher levels of PAF, which may aid in their survival.

Dietary ganglioside decreases cholesterol content, caveolin expression and inflammatory mediators in rat intestinal microdomains

Membrane microdomains rich in cholesterol and sphingolipids, including gangliosides (GGs), are known to be important regions for cell signaling and binding sites for various pathogens. Cholesterol depletion inhibits the cellular entry of pathogens and also reduces inflammatory signals by disrupting microdomain structure. Our previous study showed that dietary gangliosides increased total ganglioside incorporation while decreasing cholesterol in the intestinal mucosa. We hypothesized that diet-induced reduction in cholesterol content in the intestinal mucosa disrupts microdomain structure resulting in reduced pro-inflammatory signals. Male weanling Sprague-Dawley rats were fed semipurified diets for 2 weeks. Experimental diets were formulated to include either ganglioside-enriched lipid (GG diet, 0.02% gangliosides [w/w of diet] ) or polyunsaturated fatty acid (PUFA diet, 1% arachidonic acid and 0.5% docosahexaenoic acid, w/w of total fat), in a control diet containing 20% fat. Levels of cholesterol, GG, caveolin, platelet activating factor (PAF), and diglyceride (DG) were measured in the microdomain isolated from the intestinal brush border. The GG diet increased total gangliosides by 50% with a relative increase in GD3 and a relative decrease in GM3. Cholesterol content was also reduced by 23% in the intestinal microdomain. These changes resulted in a significant decrease in the ratio of cholesterol to ganglioside. The GG diet and the PUFA diet were both associated with reduction in caveolin, PAF, and DG content in microdomains, whereas no change occurred in the ganglioside profile of animals fed the PUFA diet. Dietary gangliosides decrease the cholesterol/ganglioside ratio, caveolin, PAF and DG content in microdomains thus exerting a potential anti-inflammatory effect during gut development.

The significance of platelet‐activating factor and fertility in the male primate: a review

Since its discovery nearly 30 years ago platelet-activating factor (PAF) has emerged as one of the more important lipid mediators known. PAF (1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphorylcholine) exists endogenously as a mixture of molecular species with structural variants of the alkyl moiety. PAF is a novel potent signaling phospholipid that has unique pleiotropic biological properties in addition to platelet activation. PAF also plays a significant role in reproduction and is present in the sperm of a number of primate species. PAF content in squirrel monkey sperm is significantly higher during the breeding season than the non-breeding season. PAF content in rhesus sperm has a significant relationship with sperm motility. PAF content in human sperm has a positive correlation with seminal parameters and pregnancy outcomes. The enzymes (lyso-PAF-acetyltransferase and PAF-acetylhydrolase) necessary for PAF activation and deactivation are present in primate sperm. PAF-acetylhydrolase may act as a "decapacitation factor". Removal of this enzyme during capacitation promotes PAF synthesis increasing primate motility and fertilization. PAF also plays a significant role in the fertilization process, enhancing the fertilization rates of oocytes. Enhanced embryo development has also been reported in oocytes fertilized with PAF-treated sperm. Exogenous PAF will also significantly improve primate artificial insemination pregnancy outcomes. PAF antagonists inhibit sperm motility, acrosome reaction, and fertilization thus suggesting the presence of receptors for PAF. The PAF-receptor is present on primate sperm, with altered transcript levels and distribution patterns on abnormal cells. Whereas, the exact mechanism of PAF in sperm function and reproduction is uncertain, its importance in normal primate fertility is substantial.

291PRESENCE OF PLATELET-ACTIVATING FACTOR (PAF) RECEPTOR IN BULL SPERM AND POSITIVE CORRELATION OF SPERM PAF CONTENT WITH FERTILITY

Male fertility involves the capacity to obtain viable pregnancy and offspring after insemination. Currently, the most common way to measure bull fertility is through non-return rates (NRR) calculated after insemination of many females. However, this method is time-consuming and expensive. A number of biochemical molecules in sperm have been proposed as potential predictors of male fertility, e.g. platelet-activating factor (PAF). Platelet-activating factor (1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphorylcholine) is a ubiquitous phospholipid that is implicated in the mediation of a wide variety of reproductive processes. The mechanism of PAF’s action is a receptor-mediated event reported to affect intracellular calcium levels. Bull sperm contain PAF and its content has a positive relationship with motility. While the PAF-receptor has been reported in other species, it has not been demonstrated in bull sperm. Therefore, our objectives were to determine: 1. the relationship between PAF content in bull sperm and Estimated Relative Conception Rates (ERCR, a 3-year rolling average of NRR); and 2. the presence of the PAF-receptor in bull sperm. Sperm PAF content for bulls (n=8) with different ERCR was determined by radioimmunoassay. PAF-receptor expression was determined as follows: total RNA was purified by acid phenol extraction and ethanol precipitation. Complementary DNAs were synthesized by reverse transcriptase with dNTPs and random primers at 37°C, 60min; followed by 65°C, 5min. Reverse transcription (cDNA) products were amplified with Taq polymerase, dNTP, and PAF receptor primer pair (upper, 5′-AATCCAGTCACCCTGGTTGTAG-3′; lower, 5′-TGGACTCAGAGTTCCGATACAC-3′) at 94°C, 1min; 55°C, 1min; 72°C, 1min for 35 cycles followed by 72°C, 7min. RT-PCR products were analyzed by 2% agarose gel electrophoresis. PAF-receptor protein was determined as follows: PBS-washed bull sperm was exposed to human PAF-receptor antibody at 4°C for 3h, washed in PBS, then exposed to fluorescein isothiocyanate-conjugated anti-IgG for 90min at 37°C, and again washed in PBS. Specimens were examined by epifluorescence microscopy at 400×. PAF content in bull sperm ranged from 1.39ng/106 sperm cells to 13.68ng/106 sperm cells. There was a positive correlation (P&amp;lt;0.05) between PAF content and ERCR. Presence of PAF-receptors in bull sperm was confirmed by immunofluorescence. However, distribution of PAF-receptors in bull sperm was not uniform within or between specimens. A cDNA clone containing the coding region for PAF-receptor was isolated from bull sperm using a reverse transcription-polymerase chain reaction protocol. There is a positive correlation (R=0.40; P&amp;lt;0.05) between PAF content in sperm and in vivo fertility of individual bulls as determined by NRR. Molecular and immunofluorescence data confirm the presence of PAF-receptor (mRNA and protein) in bull sperm. Additional studies are warranted to elucidate the mechanism of PAF’s action in sperm. Early selection for fertility in bulls represents a potentially valuable application to enhance efficiency in cattle breeding.

Fertilization potential of human sperm is correlated with endogenous platelet-activating factor content.

Platelet-activating factor (PAF) is a potent signaling phospholipid that is found in mammalian sperm and has a positive correlation with fertility. Whereas PAF is present in human sperm, there are no relational reports on its content and the cells fertilization potential. Therefore, the study objective was to determine if PAF content in capacitated-induced sperm is related to fertilization potential as determined by the sperm penetration assay (SPA). Endogenous sperm lipids were measured for PAF content by a specific radioimmunoassay following insemination of zona pellucida-free hamster ova. Data were analyzed by regression analysis and Student's t test. Regression analysis revealed a positive and significant relation (R2 = 0.806; P < 0.05) between PAF content in human sperm and SPA outcome (pass: > or = 5.0; fail: < 5.0, penetrations/ova). Patients that passed (22.61 +/- 5.21 picomoles/10(6)) the SPA had significantly (P < 0.01) higher PAF levels in their sperm than patients that failed (12.91 +/- 1.76 picomoles/10(6) cells) the test. PAF content in capacitated-induced sperm has a significant and positive relationship with fertilization potential. Fertilization potential may be predicted by measuring PAF levels in capacitation-induced human sperm. Determining PAF content in capacitated human sperm may be a beneficial diagnostic tool for the infertility specialist.

Human spermatozoan platelet-activating factor content is related to motility and morphology

Objective: Platelet-activating factor (PAF; 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphorylcholine) is a ubiquitous phospholipid present in human sperm that is implicated in the mediation of a wide variety of reproductive processes. Angle et al. (1991) reported an inverse relationship between human sperm PAF content and motility. However, animal models demonstrate a positive relationship between PAF content and motility. Recent human data also suggest that pregnancy rates following intrauterine insemination are greater for sperm exposed to exogenous PAF. Further, endogenous sperm PAF content is greater in those specimens resulting in a pregnancy during in vitro fertilization than those not resulting in pregnancy. The objective of this study was to determine the relationship between PAF content in sperm and seminal parameters.

Embryonic platelet-activating factor: an indicator of embryo viability

A definitive need exists to identify a biomarker of embryonic viability. Platelet-activating factor (PAF) production by human embryos is related to pregnancy potential. Conditioned embryo culture media were obtained following conventional IVF on day 3, with PAF levels and pregnancy outcomes correlated. Overall pregnancy rate was 68% (17/25) with a mean of 84.1 (+/- 8.5) pmol/l/embryo PAF level. PAF levels ranged from a 216.4 pmol/l/embryo (pregnant) to a 3.7 pmol/l/embryo (not pregnant). There was a significant difference (P < 0.05) in PAF content between pregnant (92.1 +/- 9.5 pmol/l/embryo) and non-pregnant groups (52.5 +/- 16.6 pmol/l/embryo). Patients were categorized into three groups based upon PAF levels: low (< or= 5 pmol/l/embryo); medium (51-100 pmol/l/embryo) and high (>100 pmol/l/embryo). The low (60%) group had a significantly (P < 0.05) lower pregnancy rate than either the medium (85%) or high (89%) groups. A receiver-operator characteristic curve predicted a cut-off limit of 45 pmol/l/embryo for PAF content in human embryo conditioned culture media. The data demonstrate a correlation between PAF levels in human embryo conditioned culture media and pregnancy outcome. Additionally, as embryonic PAF levels increase so does the corresponding pregnancy rate. Therefore, PAF may be used as an indicator of embryo viability and for predicting pregnancy outcome.

Platelet-activating factor content in boar spermatozoa correlates with fertility

The objective of this study was to evaluate the level of platelet-activating factor [1- O-alkyl-2-acetyl- sn-glycero-3-phosphorylcholine; PAF] content in spermatozoa between two groups of boars that differ in farrow rate percentages. The boar farrow rate was defined as High if it was ≥70% and Low if it was <70%. Fresh, extended semen was collected from sexually mature boars and used in the PAF extractions. Platelet-activating factor was detected in all semen samples assayed. The amount of PAF detected in spermatozoa obtained from the High group ranged from 1.90 to 11.30 pM/10 6 cells. The level of PAF in the Low group ranged from 0.92 to 4.96 pM/10 6 cells. Regression analysis revealed a positive (R 2 = 0.369) and significant (P = 0.021) relationship between PAF content in boar spermatozoa and farrow rate. Spermatozoa-derived PAF levels (mean ± SEM) were significantly higher (P = 0.015) in the High-farrow group (6.75 ± 1.25 pM/10 6 cells) than in the Low-farrow group (2.45 ± 0.51 pM/10 6 cells). The PAF content in spermatozoa was significantly higher (P = 0.035) in the High-average (≥10.5/litter) number of piglets born group (5.78 ± 1.24 pM/10 6 cells) than in the Low-average (< 10.5/litter) number of piglets born group (3.34 ± 1.19 pM/10 6 cells). Additionally, PAF content in spermatozoa was significantly higher (P = 0.034) in the High-average (≥ 9/litter) number of piglets born alive group (6.82 ± 1.35 pM/10 6 cells) than the Low-average (< 9/litter) number of piglets born alive group (3.00 ± 0.87 pM/10 6 cells). The data demonstrate that PAF is present in boar spermatozoa and that levels are significantly higher in individuals with a high-farrow rate status and high-number of piglets born and born-alive.

Platelet-activating factor content in human spermatozoa and pregnancy outcome

Objective: To determine whether platelet-activating factor (PAF) content in human spermatozoa from an isolated population is related to fertilization and pregnancy outcome. Design: Prospective analysis of PAF content in human spermatozoa after a Percoll gradient wash and its relation to fertilization and pregnancy outcome. Setting: University-based reproductive genetics laboratory. Subject(s): Couples undergoing assisted reproduction. Intervention(s): Lipids extracted from Percoll gradient spermatozoa were quantitated for PAF content by a specific radioimmunoassay. Main Outcome Measure(s): The relation between spermatozoa-derived PAF levels and motility, concentration, morphology, and fertilization and pregnancy rates were determined by using regression analysis and the Student t-test. Result(s): Radioimmunoassay and regression analysis showed a significant and positive relation between PAF content in human spermatozoa and concentration and motility indices and implantation rate. Patients who became pregnant had a significantly higher PAF content in the spermatozoa used (7.285 pmol/10 6 cells) than did patients who did not become pregnant (2.990 pmol/10 6 cells). Conclusion(s): The PAF content in human spermatozoa has a significant and positive relation with motility and concentration indices and implantation rate. Pregnancy rates but not fertilization rates may be predicted by measuring PAF levels in an isolated subpopulation of human spermatozoa.

Mechanism for the isotype dependence of antibody-mediated toxicity in Cryptococcus neoformans-infected mice.

Ab-based therapies have undergone a renaissance in recent years, but infusion-related reactions are a significant clinical problem. Administration of certain mAbs to Swiss Webster mice infected with Cryptococcus neoformans can result in acute lethal toxicity (ALT) characterized by cardiovascular collapse. The ability of a mAb to produce ALT is isotype dependent and occurs with IgG1 but not IgG3. To investigate this phenomenon, we measured spleen and liver cytokine responses and platelet-activating factor (PAF) content in mice given C. neoformans glucuronoxylomannan (GXM) followed by specific Ab of IgG1 or IgG3 isotype. We found no evidence to suggest that the differences in IgG1 and IgG3 toxicity were due to differences in chemokine or cytokine response. In contrast, liver and spleen tissue PAF content was significantly greater in mice IgG1. Furthermore, our results show differences in the response to IgG1- and IgG3-GXM complexes regarding: 1) macrophage-inflammatory protein-1alpha and monocyte chemoattractant protein-1 regulation, 2) splenic and hepatic PAF content, and 3) hepatic PAF content in infected mice. IgG1-associated ALT appears to be the result of greater production of PAF in response to IgG1-GXM complex formation. The results are consistent with the view that IgG1 and IgG3 interact with different Fc receptors. Our findings strongly suggest that the mechanism for Ab-mediated ALT is different from the cytokine release syndrome described after administration of other therapeutic mAbs.

Interaction of platelet-activating factor, spleen and atrial natriuretic peptide in plasma volume regulation during endotoxaemia in rats.

1. We studied endotoxin (lipopolysaccharide, LPS)-induced platelet-activating factor (PAF) production in various visceral organs, and the effect of PAF antagonists or splenectomy on LPS-induced changes. 2. PAF production in response to LPS was highest in the spleen, followed by ileum, heart, lung and kidneys. None was found in the liver. The splenic response was rapid, reaching 10 times the basal level at 30 min. The increased PAF content in each organ was unrelated to the enzyme activity of either macrophages or neutrophils. 3. LPS-induced hypotension and haemoconcentration were largely prevented by PAF antagonists and splenectomy. 4. Plasma volume fell, and plasma atrial natriuretic peptide (ANP) rose, after LPS administration. Splenectomy or pretreatment with PAF antagonists almost completely prevented these LPS-induced changes at 30 min, but only partially reversed them at 90 min. 5. These results suggest that during endotoxaemia: (a) the spleen is the site of the highest endogenous PAF production; (b) the initial release of ANP is dependent on the production of endogenous PAF, and a PAF-ANP interaction mediates the early plasma volume reduction; (c) plasma volume reduction as well as ANP release depend on the spleen; (d) PAF mediated the hypotensive response and its action in the spleen; and (e) sequestered neutrophils are probably not the main source of PAF in the spleen.

Correlation of desensitisation of platelet activating factor (PAF) receptors with intensity of inflammation and intestinal PAF content during experimental ileitis in guinea pig

Aim—To determine the kinetics of platelet activating factor (PAF) and prostaglandin E2 (PGE2) receptor desensitisation during intestinal inflammation induced by trinitrobenzenesulphonic acid (TNB) instillation and to study the relation between...

The platelet-activating factor receptor antagonist WEB 2170 prevents neonatal necrotizing enterocolitis in rats.

To evaluate the role of platelet-activating factor (PAF) in a neonatal rat model of necrotizing enterocolitis (NEC). NEC was reproduced in newborn rats following exposure to formula feeding, asphyxia, and bacterial colonization. The role of endogenous PAF in neonatal NEC was studied by pretreating animals with PAF receptor antagonists (WEB 2170 and WEB 2086) and by measuring intestinal PAF content in animals with NEC, WEB-treated animals, and controls. We found that WEB 2170 (dosed using 10 mg/kg in a.m. and 30 mg/kg in p.m.) markedly reduced the incidence of NEC (3/17 vs. 14/18 control: p < 0.001) and death (6/17 vs. 17/18 control; p < 0.001) compared with saline-treated animals. Although lower WEB 2170 doses prevented NEC, neither fourfold higher dosing with WEB 2170 nor similar dosing with WEB 2086 affected the incidence of disease in this study. PAF content in intestine was elevated in NEC animals (270 +/- 80 pg/g) compared with WEB 2170-treated animals (0 pg/g) and maternally fed controls (70 +/- 50 pg/g). The data support the role of PAF in the final common pathway of neonatal NEC.

The Platelet‐Activating Factor Receptor Antagonist WEB 2170 Prevents Neonatal Necrotizing Enterocolitis in Rats

Background:To evaluate the role of platelet‐activating factor (PAF) in a neonatal rat model of necrotizing enterocolitis (NEC).Methods:NEC was reproduced in newborn rats following exposure to formula feeding, asphyxia, and bacterial colonization. The role of endogenous PAF in neonatal NEC was studied by pretreating animals with PAF receptor antagonists (WEB 2170 and WEB 2086) and by measuring intestinal PAF content in animals with NEC, WEB‐treated animals, and controls.Results:We found that WEB 2170 (dosed using 10 mg/kg in a.m. and 30 mg/kg in p.m.) markedly reduced the incidence of NEC (3/17 vs. 14/18 control; p &lt; 0.001) and death (6/17 vs. 17/18 control; p &lt; 0.001) compared with saline‐treated animals. Although lower WEB 2170 doses prevented NEC, neither fourfold higher dosing with WEB 2170 nor similar dosing with WEB 2086 affected the incidence of disease in this study. PAF content in intestine was elevated in NEC animals (270 ± 80 pg/g) compared with WEB 2170‐treated animals (0 pg/g) and maternally fed controls (70 ± 50 pg/g).Conclusions:The data support the role of PAF in the final common pathway of neonatal NEC.