Biomedical subjects

M J Angle

Publications and source records attributed to M J Angle.

11 recordsLinked to original sources

PubMed1993

Effect of platelet-activating factor (PAF) on human spermatozoa-oocyte interactions.

The effect of exogenous platelet-activating factor (PAF) on human spermatozoa was examined by monitoring acrosomal status and hamster oocyte penetration. Induction of the acrosome response by PAF was dose, and time, dependent and required capacitated spermatozoa. Addition of 10(-14) mol PAF l-1 enhanced the acrosome reaction eightfold compared with controls treated with human serum albumin (HSA). Similar concentrations of lyso-PAF failed to induce acrosomal loss and preincubation of spermatozoa with CV3988, an inhibitor of PAF, prevented PAF induction of the acrosome reaction. PAF significantly increased the number of zona-free hamster oocytes penetrated compared with controls (9.8 +/- 0.5 of 25 oocytes were penetrated by control spermatozoa compared with 23.3 +/- 0.8 out of 25 oocytes penetrated after incubation of spermatozoa with 10(-14) mol PAF l-1; 93% of all oocytes were penetrated by at least one spermatozoon following incubation with PAF), and also increased the number of decondensed spermatozoa found per egg during the sperm penetration assay (from 1.7 +/- 0.3 spermatozoa/egg with control spermatozoa to 3.3 +/- 0.5 spermatozoa/egg with PAF-treated spermatozoa). PAF-induced increases in acrosome reaction and sperm penetration assay values were similar to effects obtained with human follicular fluid and were calcium dependent. Induction of the acrosome reaction by physiological concentrations of PAF appeared to be morphologically similar to the response induced by follicular fluid as assessed by electron microscopy.

Acrosome↗

PubMed1991

Platelet-activating factor induces progesterone secretion and changes in morphological appearance in luteinizing granulosa cells in vitro.

OBJECTIVE: Recent evidence indicates the involvement of platelet-activating factor (PAF) in ovarian periovulatory processes. The objective of this study was to investigate the influence of PAF on ovarian follicular cellular function. DESIGN AND INTERVENTIONS: We examined the effects of PAF on progesterone (P) secretion by cultured human luteinizing granulosa cells obtained from women undergoing in vitro fertilization. Follicular cells were cultured in serum-free conditions for 12 to 36 hours with and without PAF (at dosages of 10(-8) to 10(-14) M). RESULTS: Progesterone secretion was significantly increased at 12 and 36 hours after treatment with 10(-8) M PAF (170% +/- 40% and 210% +/- 40%, respectively) and with 10(-10) M PAF (170% +/- 30% and 180% +/- 10%, respectively). Smaller increases were seen with 10(-12) and 10(-14) M PAF. Maximal increases in P secretion in 10(-10) M PAF-treated wells occurred at 3 to 12 hours. At 36 hours, distinct morphological differences between cells in control wells and those containing PAF were noted. CONCLUSIONS: These results indicate that PAF may influence follicular cell function during ovulation and corpus luteum formation.

Cells, Cultured↗

PubMed1991

Platelet-activating factor in sperm from fertile and subfertile men.

STUDY OBJECTIVE: To examine the proposed role of platelet-activating factor (PAF) as a mediator of sperm function first by quantitating the concentration of PAF in sperm and second by incubating sperm with PAF and assessing the change in sperm motion parameters with a computerized motion analysis system. DESIGN: Retrospective, case-control study. SETTING: University hospital urology clinic. PATIENTS: Concentrations of PAF were measured in sperm from 6 randomly chosen normal donors and 8 asthenozoospermic patients. The change in sperm motion parameters was assessed in sperm from 10 randomly chosen normal donors and 7 asthenozoospermic patients. RESULTS: Platelet-activating factor concentrations were significantly higher (P less than 0.05) in spermatozoa from asthenozoospermic patients (149 +/- 18.0 fmol/10(6) sperm) than in sperm from normal donors (91.9 +/- 13.0 fmol/10(6) sperm). Exogenous PAF did not enhance the percent motility of precapacitated or capacitated sperm from either patients or donors, and computerized semen analysis revealed no enhancement of sperm motion parameters in asthenozoospermic patients after addition of PAF to either precapacitated or capacitated sperm. CONCLUSION: Platelet-activating factor does not appear to have therapeutic value as a means of enhancing sperm motility.

Case-Control Studies↗

PubMed1990

Insulin-like growth factor I (IGF-I) levels in follicular fluid from human preovulatory follicles: correlation with serum IGF-I levels.

Insulin-like growth factor I (IGF-I) levels were measured in both serum and fluid of preovulatory follicles (n = 156) in 43 women undergoing in vitro fertilization (IVF). The mean IGF-I level in follicular fluid (FF) was significantly lower than in serum (0.52 +/- 0.02 IU/L versus 0.66 +/- 0.23 IU/L), and FF levels were significantly correlated with individual serum IGF-I levels as well as with follicular size and FF volume but not with oocyte maturity, granulosa cell appearance, or IVF. This suggests that FF IGF-I levels cannot serve as a clinical indicator for the degree of oocyte/granulosa cell differentiation or a predictor for IVF. Serum IGF-I levels were inversely correlated with the number of human menopausal gonadotropin ampules administered during treatment, suggesting that IGF-I might enhance ovarian gonadotropic stimulation.

Estradiol↗

PubMed1988

Selective hydrolysis of ether-containing glycerophospholipids by phospholipase A2 in rabbit lung.

The role of phospholipase A2 (PLA2) in the simultaneous generation of lyso-platelet-activating factor and arachidonic acid was investigated by examining the calcium dependency and substrate specificity of PLA2 activities in rabbit lung microsomes. Alkylarachidonoylglycerophosphocholine (alkylarachidonoyl-GPC) was preferentially hydrolyzed as compared to acylarachidonoyl-GPC, and both arachidonate-containing substrates were cleaved to a greater extent as compared to alkyl- and acyl-substrates with oleate at the sn-2 position. Hydrolysis of alkylacyl-GPC substrates was not dependent on calcium in the presence of EGTA (1 mM); however, addition of calcium (2 mM) increased hydrolysis of acylarachidonoyl-GPC 2-fold and hydrolysis of acyloleoyl-GPC 10-fold. Substitution of an alkenyl group in the sn-1 position further enhanced calcium-independent PLA2 hydrolysis, and another substitution of arachidonic acid at the sn-2 position of the plasmalogen substrates substantially increased hydrolysis as compared to hydrolysis of substrates containing oleic acid. Hydrolysis of the choline plasmalogen was 3-fold greater than hydrolysis of the ethanolamine plasmalogen containing arachidonate. Preferential calcium-independent hydrolysis of alkylacyl-GPC substrates was observed in several tissues, including adult and fetal rabbit lung and adult rabbit kidney and human amnion. PLA2 substrate specificity may account for the preferential hydrolysis of arachidonoyl-containing alkyl-GPC in several cell types and explain the simultaneous generation of the precursors of two potent autacoids, platelet-activating factor and eicosanoids.

Aging↗

PubMed1988

Platelet-activating factor induces glycogen degradation in fetal rabbit lung in utero.

The role of platelet-activating factor (PAF, 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) in initiating glycogen breakdown in the fetal rabbit lung was assessed by intraperitoneal administration of this potent ether-linked glycerophospholipid. Forty-five min after in utero injection of PAF (2.5 X 10(-7) mol), fetal pulmonary and hepatic glycogen concentrations were reduced from 326 to 256 and from 9.8 to 6.6 micrograms of glycogen/mg protein, respectively. Glycolytic activity was similarly increased as judged by an elevation of lactate (2-fold) in lung, liver, and plasma upon PAF injection. These actions of PAF were dose- and time-dependent. The glycogenolytic response did not occur when an equimolar dose of the inactive enantiomer, D-PAF was injected. Pretreatment of the fetus with a specific PAF receptor antagonist, SRI-63-441, prevented the PAF response. We have previously demonstrated (Hoffman, D. R., Truong, C. T., and Johnston, J. M. (1986) Biochim. Biophys. Acta 879, 88-96) that PAF biosynthesis and PAF concentrations increase significantly on day 24 of fetal rabbit lung development. A concurrent decrease in pulmonary glycogen concentration at this point of gestation is potentially reflective of the PAF-induced action. Thus, these observations would suggest a role for PAF in the normal physiology of fetal lung maturation.

Animals↗

PubMed1988

Platelet-activating factor in the rabbit uterus during early pregnancy.

Platelet-activating factor (PAF) concentrations were low in the non-pregnant, oestrous uterus (mean +/- s.e.m.: 2.2 +/- 1.2 pmol/g, n = 3). However, uterine PAF increased dramatically during pregnancy to a maximum of 37.8 +/- 4.90 pmol/g (n = 7) on Day 5. By Day 7, PAF concentrations in the uteri of pregnant rabbits had returned to levels similar to those found at oestrus. In contrast, uterine PAF in pseudopregnant rabbits peaked at 30.6 +/- 2.8 pmol/g (n = 8) on Day 4, declined to 20.5 +/- 2.4 pmol/g (n = 8) on Day 5 and then remained at that concentration through Day 7. Uterine PAF co-migrated with synthetic PAF (1-O-hexadecyl-2-acetyl-sn-glycero-phosphocholine) in both thin-layer and normal-phase high-performance liquid chromatography. PAF activity in the uterus during pregnancy and pseudopregnancy was found almost exclusively in the endometrium; little or no PAF was found in myometrium, uterine flushings or blastocysts. While no PAF was detected in blastocysts on Days 5 and 6 of pregnancy, the presence of the embryo appears to modulate biosynthesis and/or degradation of PAF by the uterus, since PAF decreased significantly in uterine tissue apposed to the implanting embryo (but not in similar areas between such attachment sites). Increased concentrations of PAF in the preimplantation rabbit uterus followed by a dramatic decrease on the day of blastocyst attachment suggest that this potent inflammatory autacoid may play a vital role in implantation.

Animals↗

PubMed1987

Ontogeny of the responsiveness to intravenous platelet-activating factor.

Neonatal and young animals fail to develop antigen-induced, lethal, systemic anaphylactic reactions. Recent evidence has documented that, in the adult rabbit, an unusual phospholipid autacoid, platelet-activating factor, induces almost all of the physiologic events associated with IgE-induced anaphylaxis. Thus, in the present study, the intravascular alterations after intravenous infusion of synthetic platelet-activating factor (1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine; AGEPC) into young rabbits were examined. In comparison to 13-week-old, adult rabbits, the intravascular infusion of greater than 1.0 micrograms/kg AGEPC was not lethal in rabbits of 8 weeks of age or less. In dose-response studies, the amount of AGEPC required to induce a lethal response in 50% of the animals tested (LD50) was found to inversely correlate with age. In contrast, AGEPC-induced platelet aggregation in vitro was not affected by the age of the donor animal. Consistent with age-independent platelet responsiveness in vitro, AGEPC-induced thrombocytopenia and intravascular accumulation of platelet factor 4 and thromboxane B2 were also unaffected by animal age. Neutropenia and basopenia, as well as platelet and neutrophil sequestration in the pulmonary microvasculature after intravenous AGEPC infusion also were similarly unaffected by animal age. Although the mechanisms which modulate the profound and lethal physiologic responses following AGEPC infusion in the adult rabbit remain to be established, the current study clearly documents an age-dependent acquisition of systemic physiologic sensitivity to AGEPC and/or other mediators released as a result of intravascular AGEPC administration.

Aging↗

PubMed1986

Age-dependent differential development of leukotactic and vasoactive responsiveness to acute inflammatory mediators.

Age-associated development of increased cutaneous vascular permeability and neutrophil accumulation in response to several inflammatory mediators was examined in young rabbits. The development of increased cutaneous vascular permeability was mediator-, age- and dose-dependent and was potentiated by prostaglandin E2 (PGE2). While 4-week-old rabbits responded to bradykinin, they did not develop increased vascular permeability in response to histamine, acetyl glyceryl ether phosphocholine (AGEPC), N-formyl-methionyl-leucyl-phenylalanine, or zymosan-activated plasma at doses which induced significant increases in vascular permeability in 13-week-old rabbits. Dose-dependent increases in vascular permeability after intracutaneous injection of AGEPC and histamine were observed by 6 weeks of age although fewer animals responded to histamine as compared to AGEPC. In addition, coadministration of PGE2 allowed the expression of increased vascular permeability to AGEPC, N-formyl-methionyl-leucyl-phenylalanine and zymosan-activated plasma in all 4-week-old animals. Interstitial neutrophil accumulation as well as increased vascular permeability was also age-, time-, mediator- and dose-dependent. Compared to 13-week-old rabbits, fewer numbers of interstitial neutrophils were observed in 4-week-old animals for up to 4 hours after intracutaneous injection of AGEPC. PGE2 potentiated the neutrophil response to N-formyl-methionyl-leucyl-phenylalanine and zymosan-activated plasma in both young and adult rabbits; nevertheless, the response in young animals was never as extensive as in the adult animal with the exception of the neutrophil infiltrative response after administration of AGEPC and PGE2. These results suggest that PGE2 synthesis and/or reactivity in young animals may be significantly different from adult animals and in part may account for the lowered reactivity to acute inflammatory mediators in the young animal.

Aging↗

PubMed1983

Luminol-dependent chemiluminescence analysis of the variables of the phagocytic response by canine granulocytes.

Variables which influence the oxygen-dependent chemiluminescence (CL) response of canine polymorphonuclear leukocytes (PMN) to zymosan were examined in a luminol-dependent CL assay system. Maximal CL responses were obtained when 5 x 10(6) canine PMN, isolated from heparinized blood, were assayed at 37 degrees C in a Luminometer. The response was enhanced by the addition of 0.05 mM Luminol and inhibited by the addition of 0.06 mM sodium azide and 60 micrograms superoxide dismutase. Repeatability on a given day was very good; however, day to day variations in CL activity prevented direct comparison of phagocytic activity between days. Opsonization of zymosan in equine serum significantly reduced the CL response by canine PMN as compared to opsonization of zymosan in autologous or homologous canine serum and bovine serum. The present results show that luminol-dependent CL analysis can be used to measure phagocytosis by canine granulocytes in a luminometer and has potential use in clinical situations.

Animals↗

PubMed1979

The source of progesterone in preimplantation rabbit blastocysts.

In vitro and in vivo synthesis of progesterone, sequestration of progesterone from the surrounding medium, and its subsequent conversion to metabolites was investigated in 146 hr post coitus preimplantation rabbit blastocysts. No significant conversion of 3H-pregnenolone to 3H-progesterone was observed throughout the 8 hr incubation. Progesterone content in blastocysts and culture medium did not change during the course of an 8 hr incubation. This suggests that the failure to detect incorporation of label into progesterone was not due to the presence of a large endogenous pool of pregnenolone. Significant uptake (p less than 0.05) of 3H-progesterone from the incubation medium was observed as was significant conversion of the 3H-progesterone to unidentified metabolites. Therefore it would appear that the preimplantation rabbit blastocyst is not capable of de novo synthesis of progesterone from pregnenolone prior to implantation but sequesters progesterone from the surrounding medium and converts it to progesterone metabolites.

Animals↗