Search PubMed⌕ Search

Biomedical subjects

A D Fleming

Publications and source records attributed to A D Fleming.

At least 37 records · Page 2Linked to original sources
PubMed1990

The contribution of symptomatology and/or uterine activity to the incidence of unscheduled visits.

Home uterine activity monitoring and perinatal nursing support have been shown to be associated with a decrease in preterm births with no increase in the number of unscheduled patient visits. This prospective, randomized multicenter study compared the frequency of unscheduled visits in patients receiving home uterine activity monitoring and perinatal nursing support with that of patients receiving education regarding the detection and reporting of preterm labor symptomatology. The contribution of patient-reported signs and symptoms versus objective uterine activity data to unscheduled visits is assessed. The overall frequency of unscheduled visits was similar in both groups. In the home uterine activity monitoring and perinatal nursing support group, the contributions of uterine activity versus signs and symptoms to the diagnosis of preterm labor were equal, with 36% of patients diagnosed with preterm labor sent to the physician for increased uterine activity and 36% for signs and symptoms. The sensitivity for the group receiving monitoring and nursing support in detecting preterm labor was 93%. The majority of false-positive visits were associated with patient symptoms. These data show that this combination service does not lead to a clinically significant increase in unscheduled visits. Further, the visits resulting from the combination service provide a sensitive predictive method to aid physicians in detecting early labor.

Clinical Trials as Topic↗
PubMed1990

Relationship of uterine contractility to preterm labor.

An increased uterine contraction rate is associated with preterm labor. The contraction rate in individual patients, however, has not been evaluated critically as to its predictive value in forecasting early labor. In this randomized multicenter study, 105 patients at high risk for preterm delivery monitored their contraction rate at home on a daily basis. An analysis was conducted to determine the association of at least four contractions per hour on a routine strip followed by at least four contractions per hour on a repeat tracing with subsequent preterm labor. Using this threshold, 70% of the patients were correctly classified. This contraction rate resulted in a sensitivity of 57%, a specificity of 80%, a positive predictive value of 72%, and a negative predictive value of 68%. A threshold rate of at least four contractions per hour on a remonitor strip identifies a patient at increased risk for preterm labor (P = .003).

Cardiotocography↗
PubMed1990

Perinatal outcomes of twin pregnancies at term.

A review of a two-year experience in our community disclosed that 57% of twin pregnancies (118/207) deliver at term. Little attention has been focused on perinatal outcomes of twin pregnancies remaining undelivered after 36 completed weeks. Therefore, we reviewed our experience to determine whether our practice should change to maximize perinatal care. Nearly all the study pregnancies (115/117, or 97.5%) delivered by the estimated date of confinement. Fetal malpresentation, failure to progress and the patient's lack of desire for a vaginal birth after cesarean delivery were common reasons for the high cesarean rate (62/117, or 52%). The neonatal outcomes were favorable regardless of the route or interval between deliveries. Discordant fetal growth was found in only eight cases (6.8%). No perinatal deaths occurred, and five-minute Apgar scores less than 7 (2/234, or 0.9%) and rates of anomalies (5/234, or 2.1%) were not different from those in singleton pregnancies delivering during the same period. Using the principles of obstetric practice used in our community, we would expect the perinatal outcomes in term twin gestations to be favorable.

Cesarean Section↗
PubMed1990

Home uterine activity monitoring is associated with a reduction in preterm birth.

The value of home uterine activity monitoring plus perinatal nursing support in the prevention of preterm birth among high-risk patients has been demonstrated by several studies. Other reports with less stringent guidelines and less intensive nursing contact have questioned the contribution of home uterine activity monitoring and perinatal nursing support to a preterm birth prevention program. In this large, prospective, randomized multicenter study, patients were assigned to receive either daily monitoring and nursing contact or a preterm birth prevention program including intensive education and more frequent prenatal visits. Among the monitored patients, there was a significant increase in early detection of preterm labor (2 cm or less), successful tocolysis, and prolongation of pregnancy to term. Thirty-one percent of these diagnoses of preterm labor resulted from evaluation of increased uterine activity without associated patient-perceived symptoms. We conclude that a program of daily uterine activity monitoring and perinatal nursing support results in earlier diagnosis of preterm labor and subsequently more effective tocolysis.

Cardiotocography↗
PubMed1990

Preventing preterm birth in twin gestation: home uterine activity monitoring and perinatal nursing support.

In this investigation, 45 women with twin gestations in four centers were randomly assigned to either daily home uterine activity monitoring and perinatal nursing support (19) or an education group (26). Patients in the home uterine activity monitoring and perinatal nursing support group monitored uterine activity twice daily, transmitted the data each day, and had 24 hour-a-day access to nursing support. Education patients were counseled regarding the common signs and symptoms of preterm labor. Both groups had scheduled prenatal visits at least every 2 weeks. Sixteen (62%) of the education group and 14 (74%) of the home uterine activity monitoring and perinatal nursing support group developed preterm labor, values that were not significantly different. Of the monitored group who experienced preterm labor, all 14 were dilated 3 cm or less at diagnosis of the first preterm labor, compared with ten of 16 in the education group (P = .01; one-tailed Fisher test). The mean cervical dilatation at the first preterm labor episode in the group receiving daily monitoring and contact (1.6 cm) was significantly less (P = .01) than that in the education group (2.9 cm). Thus, fewer preterm births were recorded in the home uterine activity monitoring and perinatal nursing support group and significantly fewer patients delivered because of failed tocolysis (P = .03).

Adult↗
PubMed1990

Management of preterm labor patients at home: does daily uterine activity monitoring and nursing support make a difference?

Daily home uterine activity monitoring and perinatal nursing support were compared with standard care in managing patients with recurrent preterm labor during the current pregnancy in an effort to reduce preterm birth. Sixty-seven successfully treated preterm labor patients were randomly assigned in this multicenter study to daily home uterine activity monitoring and perinatal nursing support or to a standard-care group. Recurrent preterm labor occurred in 15 (45%) of monitored patients and 19 (56%) of standard-care patients. The risk of preterm birth (before 37 weeks) for patients with recurrent preterm labor was significantly reduced (P = .025) in the monitored group (seven, or 47%) compared with the standard-care group (16, or 84%). The relative risk of delivering because of failed tocolysis was 2.8 for the standard-care group versus the monitored group. There were no patients in the monitored group who delivered at the first recurrence of preterm labor for failed tocolysis. The data suggest that home uterine activity monitoring and perinatal nursing support are helpful in achieving term birth through earlier detection and treatment of recurrent preterm labor.

Adult↗
PubMed1989

Is a Ca2+ -ATPase involved in Ca2+ regulation during capacitation and the acrosome reaction of guinea-pig spermatozoa?

The Ca2+-ATPase antagonists quercetin and ethacrynic acid accelerated the onset of the acrosome reaction in guinea-pig spermatozoa incubated in the continuous presence of Ca2+, whereas furosemide had no effect, and sodium orthovanadate only affected sperm motility. When spermatozoa were preincubated in a 'Ca2+-free' medium, quercetin and ethacrynic acid shortened capacitation time: spermatozoa incubated for 1 h in 100-200 microM-ethacrynic acid showed 60-80% acrosome reactions when Ca2+ was added. Such spermatozoa were able to fertilize zona-free hamster eggs. Our results therefore point to the possible involvement of a Ca2+-ATPase in the regulation of intracellular Ca2+ in spermatozoa. Cysteine and dithiothreitol, both disulphide reducing agents, prevented the effects of quercetin and ethacrynic acid, suggesting that sulphydryl groups may be important for the expression of Ca2+-ATPase activity. Lysophosphatidylserine (LS) also prevented the stimulatory effect of ethacrynic acid, an effect similar to that shown by LS on lysophosphatidylcholine (LC). It is argued that both LS and LC could exert their action through an effect on the Ca2+-ATPase.

Acrosome↗
PubMed1986

Labelling of living mammalian spermatozoa with the fluorescent thiol alkylating agent, monobromobimane (MB): immobilization upon exposure to ultraviolet light and analysis of acrosomal status.

Living spermatozoa of seven mammalian species were treated with the thiol-alkylating fluorescent labelling compound, monobromobimane (MBBR). MB-labelling alone had no effect on sperm motility, nor on the time course or ability of golden hamster spermatozoa to undergo the acrosome reaction when capacitated in vitro. Exposure of MB-labelled spermatozoa to ultraviolet (UV) light and excitation of the MB fluorochrome resulted in virtually immediate immobilization of the spermatozoa without affecting acrosomal status. UV exposure of unlabelled spermatozoa for up to 30 sec had no effect upon motility. Immobilization of MB-labelled spermatozoa depended on the midpiece being irradiated, as irradiation of the head alone, or of the more distal parts of the principal piece, had little or no effect upon motility. Labelling with MB followed by immobilization of individually selected spermatozoa was most useful for detailing the course and site of occurrence of the acrosome reaction during penetration of the cumulus oophorus by golden hamster spermatozoa in vitro. In these often hyperactivated spermatozoa, precise determination of the acrosomal status could not often otherwise be made due to the difficulty in visualizing the acrosomal region of a vigorously thrashing, hyperactivated spermatozoon. This technique should prove valuable in a variety of studies on sperm motility, capacitation and fertilization, and could also be extended to other cell systems.

Acrosome↗
PubMed1986

Normal development of hamster and rabbit eggs fertilized by spermatozoa labelled with the fluorescent thiol alkylating agent, monobromobimane.

Cauda epididymal spermatozoa of the golden hamster were labelled with the thiol-alkylating reagent, monobromobimane (MB). Female hamsters underwent uterine insemination with labelled spermatozoa at laparotomy under metofane anesthesia. All 12 females examined between 5 and 54 h postinsemination yielded a total of 83/100 (83%) eggs in the process of fertilization or embryos. Under ultraviolet (UV) exposure all exhibited a fluorescent tail which, in the 4- and 8-cell embryos, could be seen to be fraying or disintegrating. As cleavage progressed, labelled tail components came to be restricted among the blastomeres such that at the 4- and 8-cell stage the tail could be seen in only one to three blastomeres. To study complete development and pregnancy another 12 females received uterine insemination. After recovery from anesthesia (approximately equal to 4 h) these females were mated with a vasectomized male bearing a dominant genetic marker (black eyes) to allow unequivocal determination of paternity in the fetuses and young produced. Seven became pregnant with one female losing her pregnancy about Day 7 of gestation. Two females sacrificed on Day 13 produced 17 normal fetuses and one resorption. Four females delivered 16 young, all normal at birth and in subsequent growth and fertility. In addition, insemination of female rabbits with MB-labelled spermatozoa yielded normal embryos (50/52 96%) from 3 does on Day 2 and (38/64 60%) from 4 does on Days 4 or 5. Two normal litters (9 bunnies) have delivered from 3 does allowed to carry to term.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Effects of polyamines upon capacitation and fertilization in the guinea pig.

The effects of polyamines upon the ability of guinea pig spermatozoa to undergo the acrosome reaction and upon sperm-egg fusion were investigated. All of the polyamines (polyarginines and compound 48/80) stimulated the occurrence of the acrosome reaction, although differences in the duration of the preincubation period required were noted. The stimulatory effect of the polyarginines could not be reversed by washing, while that of 48/80 was abolished by its removal prior to induction of the acrosome reaction. Polyarginine-treated spermatozoa were fully capable of fertilizing intact guinea pig eggs. In contrast, 48/80 completely blocked sperm-egg fusion at only 5-10 micrograms/ml. This inhibition was reversible by washing either treated gamete. The ability of polyamines which may also be present at the time and site of fertilization, in vivo, to inhibit or stimulate gamete functions or interactions is discussed.

Analysis of Variance↗
PubMed1985

Effects of temperature upon capacitation of guinea pig spermatozoa.

Spermatogenesis in many mammalian species requires a temperature a few degrees below body core temperature. Upon ascent through the male tract and deposition in the female tract, the temperature of spermatozoa is increased to body core temperature. This report investigates the effects of temperatures above or below normal body core temperature, which is also the usual temperature of in vitro gamete incubations and fertilization, upon sperm acrosome reacting ability and fertility. Epididymal guinea pig spermatozoa were preincubated in a Ca2+-free medium at temperatures of 15 degrees C, 25 degrees C, 37 degrees C, or 44 degrees C for increasing periods of time. At 15 degrees C or 25 degrees C, no or very few spermatozoa acquired the ability to acrosome react upon exposure to Ca2+ even after 18 hr of culture or warming up to 37 degrees C. A known stimulator of acrosome-reacting ability, lysophosphatidylcholine, was ineffective in promoting acrosome-reacting ability in spermatozoa incubated at 15 degrees C or 25 degrees C. At 37 degrees C the percentage of acrosome reaction increased steadily over time, reaching about 65% after 18 hr. At 44 degrees C the time course of acquisition of acrosome-reacting ability was greatly accelerated with a percentage at 2 hr comparable to that achieved at 37 degrees C only after 18 hr of preincubation. This effect of incubation at 44 degrees C could be reversed by cooling the spermatozoa to 37 degrees C before they were exposed to Ca2+. Spermatozoa induced to undergo the acrosome reaction after preincubation at 44 degrees C were fully capable of fertilizing intact guinea pig eggs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Evidence suggesting the importance of fatty acids and the fatty acid moieties of sperm membrane phospholipids in the acrosome reaction of guinea pig spermatozoa.

When guinea pig spermatozoa were preincubated 1 hr in Ca2+-free medium containing dilysocardiolipin (100--125 micrograms/ml) then exposed to Ca2+, the majority underwent an immediate acrosome reaction. Monolysocardiolipin was much less effective and the native cardiolipin was totally ineffective. Some fatty acids added to the medium could also render the spermatozoa capable of undergoing their acrosome reactions, arachidonic acid in methyl ester form being most potent. It is known that sperm membrane contains phospholipase A which cleaves membrane phospholipids into lysophospholipids and fatty acids. Most lysophospholipids are known to be potent acrosome reaction-promoting agents. As some forms of fatty acids are also potent acrosome reaction-promoting agents, both products of membrane phospholipid hydrolysis by phospholipase A (i.e., both fatty acids and lysophospholipids) may work synergistically to effect the conversion of stable sperm membranes to a fusion competent state capable of engaging in the acrosome reaction.

Acrosome↗
PubMed1984

Successful fertilization in vitro of fresh intact oocytes by perivitelline (acrosome-reacted) spermatozoa of the rabbit.

The ability of supplementary rabbit spermatozoa recovered from the perivitelline space of fertilized eggs to penetrate and fertilize fresh oocytes was determined. One-cell cell embryos were recovered from superovulated does approximately 4 hours after ovulation. The perivitelline spermatozoa were released by rupturing the zona pellucida of mechanically and enzymatically denuded 1-cell embryos and then fresh cumulus-intact oocytes were added. Fertilization of fresh oocytes was evaluated by pronuclei and second polar body formation. Thirty-three of 143 oocytes (24%) were fertilized by perivitelline spermatozoa. Of these, eight (24%) progressed to normal 2-cell embryos in vitro. These data suggest that some completely acrosome-reacted perivitelline rabbit spermatozoa retain the ability to penetrate the cumulus, bind and penetrate the zona pellucida, and fuse with the vitellus of fresh intact unfertilized oocytes to initiate apparently normal embryonic development.

Animals↗
PubMed1983

Porcine follicular fluid does not inhibit maturation of rat oocytes in vitro.

Follicular fluid from small-(1-2 mm) or medium-(3-8 mm) sized pig follicles was collected under conditions designed to minimize possible alteration or degradation of native fluid components. The effects of follicular fluid with or without benzamidine, an inhibitor of proteolytic activity, on oocytes collected 20 or 44 h after PMSG treatment of rats were examined. A follicular fluid fraction of Mr less than 10 000 (PM-10 membrane filter) was also tested. Follicular fluid from small- and medium-sized follicles and control medium alone supported maturation of oocytes collected 20 or 44 h after PMSG, but follicular fluid (50%) from medium-sized follicles containing 5 X 0 mM-benzamidine significantly inhibited oocyte maturation. Comparable inhibition was also observed with medium containing 5 X 0 mM-benzamidine. The PM-10 filtrate failed to inhibit oocyte maturation as assessed by germinal vesicle breakdown but did significantly inhibit first polar body formation and therefore restricted the extent of maturation. The results indicate that native pig follicular fluid is unable to inhibit the initiation of maturation of rat oocytes in vitro.

Animals↗
PubMed1982

Fertile life of acrosome-reacted guinea pig spermatozoa.

To study the fertile life of acrosome-reacted guinea pig spermatozoa, spermatozoa were induced to undergo a synchronous acrosome reaction after which vigorously motile acrosome-reacted spermatozoa were isolated from acrosome-intact ones. Acrosome-reacted spermatozoa thus prepared were incubated in vitro for various periods of time before they were mixed with zona-intact and zona-free eggs. Such spermatozoa retained their ability to fertilize zona-intact eggs for at least 2 hours after the acrosome reaction; thereafter they rapidly lost this ability. There was a close correlation between the decline and loss of the ability to penetrate the zona and the loss of hyperactivated motility by spermatozoa, indicating the importance of vigorous motility in passing through the zona. The ability of acrosome-reacted spermatozoa to fertilize zona-free eggs was maintained for many hours even after the spermatozoa had completely lost their capacity to fertilize zona-intact eggs. As long as acrosome-reacted spermatozoa are "alive," they seem to retain the capacity to fuse with the egg plasma membrane regardless of the quality of their motility.

Acrosome↗
PubMed1982

A progesterone binding component in porcine ovarian follicular fluid.

Steroid hormone concentrations (progesterone, oestrone, oestradiol-17 beta) in porcine follicular fluids were measured by radioimmunoassay. In confirmation of several previous studies, as follicular maturation proceeded, the concentrations of all three steroids increased, although the relative amounts of the oestrogens decreased compared to progesterone. Analysis of fluids for steroid-binding components was undertaken using ion-exchange chromatography, gel filtration and steroid-binding assays. Evidence is presented in support of a labile binding component which exhibits high affinity and low capacity for progesterone and little or no affinity for oestadiol. Our findings are discussed in relationship to the known retention of progesterone within preovulatory follicles and to previous reports of steroid-binding components in follicular fluids.

Animals↗
PubMed1981

Only acrosome-reacted spermatozoa can bind to and penetrate zona pellucida: a study using the guinea pig.

We have examined the behavior of guinea pig spermatozoa towards the guinea pig zona pellucida in vitro. Experiments were designed to determine whether the state of capacitation or the acrosome reaction determined the ability of the spermatozoa to attach to the zona. Freshly collected cauda epididymal spermatozoa are acrosome-intact (AI) and, by definition, uncapacitated. These cells could not attach (at least persistently) to the zona. We then sampled spermatozoa from the progressively capacitating population at various time intervals. At no point did AI spermatozoa from such samples have the ability to attach to the zona. On the other hand, acrosome-reacted (AR) spermatozoa that appeared in increasing number during this capacitation period rapidly and firmly adhered to the zona. Adhesion by AR spermatozoa prepared in several ways culminated in successful zona penetration and fertilization of the ovum. The data provide unequivocal evidence that AR guinea pig spermatozoa attach to zonae and fertilize the ova. We find no evidence that AI spermatozoa firmly attach or bind to the zona, regardless of their state of capacitation.

Acrosome↗