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Biomedical subjects

W A Bennett

Publications and source records attributed to W A Bennett.

31 records · Page 2Linked to original sources
PubMed1993

Parturitional factors associated with membrane stripping.

OBJECTIVE: Our purpose was to determine what factors occurring after digital separation of the chorionic membranes from the lower uterine segment (membrane stripping) are involved in observed clinical changes compared with patients not so treated. STUDY DESIGN: Thirty patients were randomly divided among a study population and two control groups to assess uterine contractions and microbiologic, histologic, and biochemical markers associated with parturitional events over a 7-hour time frame. RESULTS: Clinically, an increased frequency of uterine contractile activity was observed among patients in the membrane-stripped group (p < 0.03). There was a significant increase in plasma 13,14-dihydro-15-keto-prostaglandin F2 alpha (p < 0.001) and endocervical phospholipase A2 activity (p < 0.04) among those who underwent membrane stripping. Blood leukocyte counts, sedimentation rates, prostaglandin E2 metabolite concentrations, and fibronectin levels revealed no significant change during the 7-hour study session. CONCLUSION: Membrane stripping was associated with increases in phospholipase A2 activity and prostaglandin F2 alpha concentrations, indicating a possible correlation with initiation of the cascade of parturitional events.

Amnion↗
PubMed1990

Hydatidiform mole pregnancy trophoblast extracts differentially suppress interleukin-2-induced proliferation of human T-lymphocytes and PHA-blasts.

Immunoregulatory factors of trophoblast origin may partially abrogate maternal immune responses to the fetus during pregnancy. We have previously shown that soluble factors extracted from hydatidiform mole trophoblast suppress interleukin-2 (IL-2)-dependent proliferation of a cloned murine cytotoxic T cell line (CTLL-2). To characterize human T cell responses to this trophoblast extract, we measured the effects of molar tissue extracts (HME) on IL-2-stimulated proliferation of human T-lymphocytes and mitogen (PHA) transformed T-cell blasts (PHA-blasts). HME significantly (P less than 0.05) suppressed T-lymphocyte proliferation in response to 5 and 10 units/ml of IL-2 at 500 and 250 micrograms/ml, while no effect was observed at the 100 micrograms/ml concentration. Suppression by HME of IL-2-stimulated T-cell proliferation was partially overcome by the addition of excess IL-2. HME also suppressed (P less than 0.05) IL-2-stimulated proliferation of PHA-blasts at 500 and 250 micrograms/well at both 5 and 10 units/ml of IL-2. As observed with resting T-cell responses, no suppression of PHA-blast proliferation was observed using 100 micrograms/ml of HME. In contrast to the response of the resting T-cells to excess IL-2, HME suppression of IL-2-stimulated blast proliferation was not affected by increasing the concentration of IL-2. These results indicate that extracts from hydatidiform mole trophoblast contain immunosuppressive factors that block human T-cell clonal expansion by inhibiting the utilization and/or production of IL-2. Furthermore, the effects of HME are not reversed by excess IL-2 when PHA-blasts are reacted compared to resting T-cell responses, which are partially reversed in the presence of excess IL-2.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Survival↗
PubMed1989

Suppression of lymphocyte proliferation in vitro by macromolecules in the vesicle fluid and tissue extracts of hydatidiform mole.

This study examines the effects of vesicle fluid and tissue extracts from hydatidiform mole trophoblast on lymphocyte proliferation in vitro. Samples were obtained by direct aspiration of vesicles (hydatidiform mole vesicle fluid (HMF] or homogenization of molar tissues (hydatidiform mole extract (HME] following therapeutic uterine evacuation of hydatidiform mole. Dialyzed and lyophylized HMF pooled from two patients exhibited a 30% suppression (P less than 0.05) of mitogen-induced lymphocyte proliferation at a concentration of 12.5 micrograms protein/ml. Similarly, lymphocyte transformation was significantly suppressed (P less than 0.05) by HME at concentrations of 500 and 250 micrograms/ml. Molecular weight chromatography of HME resolved 4 protein fractions. Fraction 3 (35--50 kDa) and fraction 4 (less than 35 kDa) significantly suppressed mitogen-induced lymphocyte transformation while fractions 1 and 2 demonstrated no immunosuppression. Heat treatment (56 degrees C, 30 min) abolished the immunosuppressive activity of HME as well as fractions 3 and 4. These results suggest that hydatidiform mole trophoblast contains heat-labile macromolecules which suppress mitogen-mediated lymphocyte transformation. Such trophoblast-derived factors may interfere with maternal rejection of the allograft.

Female↗
PubMed1988

Estrogen induces estrus unaccompanied by a preovulatory surge in luteinizing hormone in suckled sows.

The objective was to determine if progressive changes occurred in incidence of estrus and patterns of luteinizing hormone (LH) after estradiol benzoate (EB) administration at three stages of lactation. Estradiol benzoate (800 micrograms) was injected at the beginning of the second (7.8 +/- 0.3 days, range 7-8, n = 4), third (15.6 +/- 0.3 days, range 15-16 days, n = 5), or fourth (23.3 +/- 0.5 days, range 22-24, n = 4) wk of lactation. Interval to estrus (h) and proportion in estrus (in parentheses) were 72 (1/4), 88.5 (4/5), and 99 (4/4; pooled SEM = 3.5) for the second, third, and fourth weeks, respectively. Only one animal ovulated during lactation (third week). This animal had a progesterone concentration of 17 ng/ml 1 wk after estrus and an LH concentration above 2.0 ng/ml for 72 through 90 h after EB. In other sows, LH remained less than 1.0 ng/ml after EB. Patterns of LH after EB in sows treated during the fourth week of lactation were increased to a maximum of 0.76 ng/ml by 120 h after EB, which was greater than for those treated during the second or third week (maxima of 0.38 and 0.32 ng/ml, respectively; pooled SEM = 0.07; p less than 0.05). Concentrations of LH in sows that exhibited estrus were greater both before and after treatment than in sows that did not exhibit estrus after EB (p less than 0.05). By 2 wk after weaning, 8 sows had ovulated (6 of these exhibited estrus), and there were no effects of stage of lactation on these responses. We concluded that the behavioral responsiveness to EB increased as lactation progressed. The increased LH in sows treated during the fourth week indicated a partial recovery of the positive feedback response to EB. These data suggested that separate mechanisms caused behavioral and gonadotropin responses to EB in lactating sows.

Animals↗
PubMed1988

Hydatidiform mole macromolecules inhibit interleukin-2-mediated murine lymphocyte proliferation in vitro.

Macromolecules extracted from hydatidiform mole trophoblast inhibit mitogen-induced lymphocyte proliferation. To characterize the mechanism of this immunomodulation, we determined the effects of hydatidiform mole vesicle fluid (HMF) and tissue extracts (HME) on lymphokine function in vitro. Utilization of interleukin-1 (IL-1) and interleukin-2 (IL-2) were determined by using a lymphoma cell line (LBRM-33-1A5) and a murine T cell line (CTLL2), respectively. HMF suppressed (P less than .05) IL-2-dependent CTLL2 cell proliferation at 500 (36.4% of controls) and 50 (74.9% of controls) micrograms/ml. HME also suppressed CTLL2 proliferation (P less than .05) at 500 (46.0% of controls), 100 (67.2% of controls), 50 (71.5% of controls), and 10 (85.4% of controls) micrograms/culture ml. In contrast, HMF exhibited no effect on IL-1-stimulated LBRM-33-1A5 production of IL-2. However, 500 micrograms/ml of HME inhibited (P less than .05) IL-2 production (63.0% of controls) in the IL-1 utilization assay. This suppressive effect was probably due to a carry over of HME from the LBRM-33-1A5 culture to the target cells (CTLL2) used to measure IL-2 production. Molecular weight chromatography of an HME sample eluted an IL-2 inhibitor in a low molecular weight (35-50 kd) and high molecular weight (greater than 250 kd) fraction. These data suggest that one way in which macromolecules derived from hydatidiform mole could interfere with in vitro immunologic responses is by modulating interleukin-2 function.

Animals↗
PubMed1988

Patterns of oviducal motility in the cow during the oestrous cycle.

Microtransducers sensitive to changes in internal diameter were chronically implanted in the oviducts of 5 dairy cows. Motility patterns were recorded throughout 9 oestrous cycles. Cyclic variations in patterns of motility were observed and compared with circulating concentrations of plasma progesterone. Luteal-phase motility patterns were of low amplitude and frequency. The frequency and amplitude of motility increased 3-5 days before behavioural oestrus. This activity consisted primarily of longitudinal muscle contractions, with an interspacing of circular muscle activity occurring during oestrus. Patterns of activity after oestrus were similar to those before oestrus, with activity decreasing 3-5 days after oestrus. Transducers implanted bilaterally in 2 animals permitted observation of asynchronous patterns between right and left oviducts. Preliminary data suggested a higher level of activity in the oviduct ipsilateral to the active ovary. These variations may be due to a local effect, possibly mediated by the functional ovary or the ovum.

Animals↗
PubMed1987

Influence of season on estrous and luteinizing hormone responses to estradiol benzoate in ovariectomized sows.

The objective of this experiment was to determine whether seasonal differences existed in estrous and LH responses to estradiol benzoate (EB) in ovariectomized sows. Sows were ovariectomized after weaning their first litter, and treatment was begun 120 d after ovariectomy. Sows were given 400 mug EB intramuscularly (i.m.) on July 24, 1982 (summer), October 24, 1984 (fall), January 29, 1985 (winter), and March 27, 1985 (spring). Beginning 24 h after EB, sows were checked for estrus four times daily. Proportion in estrus was affected by season, with all sows exhibiting estrus within 5 d after EB in summer, winter, and spring. Only three of five sows exhibited estrus within 5 d after EB in fall. Interval (h) to estrus was delayed in fall (80 h) compared to other seasons (62.6 h; SEM = 4.5). Concentrations of LH were suppressed within 6 h after EB in all seasons but rebounded to pre-injection levels more slowly in fall and spring than in winter and summer. Frequency of LH peaks (3.2 +/- .4 4 h ) was not affected by season, but amplitude (1.9 vs 0.9 ng/ml) and baseline (2.7 vs 1.6 ng/ml) were greater (P < 0.05) for summer than for the other seasons combined. At 6 h after injection, concentrations of estradiol-17beta (pg/ml) were greater in summer (58.3) than in fall (19.0), winter (32.4), or spring (16.6; SEM = 10.4). We conclude that environmental factors associated with season alter responsiveness of the brain to estradiol, thereby controlling sexual behavior and LH secretion.

Journal Article↗
PubMed1987

Enhancement of ovulation rate in gilts by increasing dietary energy and administering insulin during follicular growth.

Two experiments were conducted to examine influences of dietary energy and insulin on ovulation rate and patterns of luteinizing hormone (LH), follicle stimulating hormone (FSH), glucose, insulin and estradiol in gilts during 6 d before estrus. In Exp. 1, 36 gilts were given altrenogest for 14 d to synchronize estrus. In a factorial arrangement, gilts were fed one of two levels of dietary energy (5,771 or 9,960 kcal metabolizable energy (ME)/d), and given one of two levels of porcine insulin (0 or .1 IU/kg body weight iv every 6 h). Dietary treatments began 4 d before and insulin treatments began 1 d after the last day of altrenogest, respectively, and lasted until 24 h after estrus. Main effect means for number of corpora lutea were 14.0 +/- 1.3 and 17.6 +/- .9 for 5,771 and 9,960 kcal ME (P less than .05), and 14.6 +/- 1.0 and 17.0 +/- .9 for 0 and .1 IU insulin (P less than .05). Number of LH peaks on d 3 was greater for gilts that received 9,960 kcal than 5,771 kcal (3.3 +/- .2 vs 2.7 +/- .2; P less than .05), and for .1 than 0 IU insulin (3.2 +/- .2 vs 2.7 +/- .2; P less than .05). During the first 24 h of sampling, concentrations of LH and FSH were greater (P less than .05) in gilts receiving 9,960 kcal ME plus insulin than for other treatment combinations. Concentrations of estradiol were not affected by treatments. In Exp. 2, two formulations of insulin were evaluated for influence on ovulation rate. All gilts received altrenogest and 9,960 kcal ME/d as in Exp. 1. Then on the first day after altrenogest, seven gilts each received short-acting insulin (as in Exp. 1), long-acting insulin (zinc suspension, 1.0 IU/kg body weight every 18 to 24 h), or served as controls. Ovulation rates were increased (P less than .05) by both insulin preparations (15.6, control; 19.1, short-acting; 18.5, long-acting; SE = 1.2). Concentrations of LH tended to be greater after short-acting insulin, but differences were not significant (P = .13). We conclude that increases in ovulation rate produced by dietary energy and insulin are not necessarily accompanied by changes in gonadotropins or estradiol.

Animals↗
PubMed1977

Primary plasmacytoma of the atrium. Report of a case with successful surgical management.

A 44-year-old woman with a superior caval syndrome was found to have an isolated plasmacytoma of the right atrium causing partial obstruction of the superior and inferior vena cavae. The tumor was excised locally, and after operation, irradiation was given. There has been no local recurrence or systemic disease demonstrated after 30 months. This is the first reported surgical excision of an intracardiac plasmacytoma.

Adult↗
PubMedDate not supplied

Reduced placental perfusion causes an increase in maternal serum leptin.

OBJECTIVE: We tested the hypothesis that the inadequately perfused placenta increases production of leptin, which can be detected in maternal serum. STUDY DESIGN: Sprague-Dawley rats (n=13), on day 14 of gestation, had placement of clips on the aorta and the ovarian arteries providing 35 per cent occlusion of the vessels. Eight rats had sham surgery and 14 rats served as non-surgical controls. All animals were sacrificed on day 19 of gestation. Maternal serum was obtained, and pups and placentae were weighed. RESULTS: Both placental weights and pup weights were reduced due to reduced uterine perfusion and were negatively correlated with maternal serum leptin (P=0.018 and 0.028, respectively). Maternal serum leptin was increased in the treatment group (2.21 ng/ml+/-64 ng/ml) compared to controls (1.66 ng/ml+/-38 ng/ml) (P=0.031). CONCLUSIONS: Our findings suggest that reduced placental perfusion results in an increase in maternal serum leptin. Further investigation is needed to determine if maternal serum leptin may be useful in identifying pregnancies with uteroplacental insufficiency.

Animals↗
PubMedDate not supplied

Secretory component in human amniotic fluid and gestational tissues: a potential endogenous phospholipase A2 inhibitor.

OBJECTIVES: Prostaglandins (PGs) are essential mediators of labor during human pregnancy. Phospholipase A2 (PLA2) provides the essential substrate for PG synthesis through the liberation of arachidonic acid from membrane phospholipid stores. Nonlaboring amniotic fluid (NL-AF) contains secretory component (SC)-like protein(s) that suppress in vitro PLA2 activity. This study characterizes the biologic activity, identity, and tissue distribution of these protein(s) in NL-AF and gestational tissues. METHODS: Third-trimester NL-AF was collected by amniocentesis, fractionated by ammonium sulfate precipitation, and submitted to an in vitro PLA2 assay. Identity of the PLA2 inhibitor in NL-AF was confirmed by Western blot and antibody neutralization studies. Secretory component-immunoreactive proteins were purified by immunoaffinity chromatography and visualized by sodium dodecyl sulfate-gel electrophoresis. Tissue distribution of SC in gestational tissues was determined by immunohistochemistry. RESULTS: The 100% pellet and supernatant fractions of NL-AF suppressed PLA2 activity, and this activity was neutralized by a polyclonal antibody to SC. Western blot studies revealed an SC-reactive protein in the 70-80-kD range in the 100% pellet fraction of NL-AF. Two SC-reactive proteins were detected in the 60-80-kD range in the eluate from the SC immunoaffinity column, along with minor proteins of 30 and greater than 100 kD. Immunohistochemical studies revealed SC in placental trophoblast, amniotic membranes, and decidual epithelium. CONCLUSIONS: These results demonstrate that proteins homologous to SC are present in human gestational tissues and possess anti-PLA2 activity. These proteins may contribute to the maintenance of pregnancy by suppressing local PG production.

Amniocentesis↗