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M D Mitchell

Publications and source records attributed to M D Mitchell.

At least 91 records · Page 5Linked to original sources
PubMed1996

Regulation of cultured human chorion cell chemokine production by group B streptococci and purified bacterial products.

PROBLEM: To determine if different strains of group B streptococci (GBS) and purified bacterial products regulate chemokine production by cultured human chorion cells. METHOD OF STUDY: Primary cultures of human chorion cells were established from placentae isolated from normal women at term gestation having repeat cesarean section. Five different strains of heat-killed GBS were incubated with confluent chorion cells at 10(7) bacteria/ml for 16 hours at 37 degrees C. In separate experiments, lipoteichoic acid and sialic acid at various concentrations were incubated with chorion cells for 16 hours at 37 degrees C. Culture supernatants were collected and then assayed to determine concentrations of interleukin-8 (IL-8) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) by ELISA. RESULTS: We found that GBS stimulated chorion cell production of MIP-1 alpha in a strain-specific fashion. We also found that both lipoteichoic acid and sialic acid stimulated concentration-dependent increases in chorion cell IL-8 production. Chorion cells, however, did not increase MIP-1 alpha production in response to either lipoteichoic acid or sialic acid. Two strains of GBS tested induced concentration-dependent increases in both IL-8 and MIP-1 alpha, but both stimulated IL-8 production to a greater extent. Similarly, IL-1 beta also caused chorion cells to produce more IL-8 than MIP-1 alpha. CONCLUSIONS: Our data are the first to show that GBS and purified bacterial products can stimulate chemokine production by fetal gestational tissues. We suggest that chorion cells may produce specific types of chemokines to attract different types of inflammatory cells and thus may participate in the pathophysiology of infection-mediated preterm labor by directing specific inflammatory responses.

Amniotic Fluid↗
PubMed1995

The regulation of arachidonate lipoxygenase metabolite formation in cells derived from intrauterine tissues.

Products of arachidonic acid (AA) metabolism via the lipoxygenase pathways may have key roles in the maintenance of pregnancy and the onset of labor. We have determined whether calcium ionophores can modulate the rate of biosynthesis within the uterus of five important arachidonate lipoxygenase metabolites, i.e. leukotriene B4 (LTB4), LTC4, 5-hydroxyeicosatetraenoic acid (5-HETE), 12-HETE, and 15-HETE. Amnion, chorion, and decidual cells were isolated, grown to confluence and incubated with ionomycin. The production of LTB4, LTC4, 5-HETE, 12-HETE, and 15-HETE was determined using specific radioimmunoassays. Cell-specific, concentration-related stimulatory actions of ionomycin on 5-HETE, 12-HETE, 15-HETE, and LTC4 but not LTB4 production were found. A23187 had effects similar to ionomycin. Hence elevation of intracellular calcium levels can result in enhanced intrauterine production of arachidonate lipoxygenase metabolites that may affect pregnancy outcome.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1995

Prostaglandins and parturition.

It seems likely that prostaglandins play a significant part in the mechanisms of parturition both at term and preterm. Concentrations of prostaglandins are increased in the blood, urine and amniotic fluid during labour. There are differences in the concentrations of prostaglandins in amniotic fluid from the forebag and hindbag. Nevertheless, if liquor is sampled only from the hindbag a highly significant increase in prostaglandin concentrations occurs throughout labour. Furthermore, we now have evidence that prostaglandin concentrations in amniotic fluid increase before the onset of labour. Prostaglandins are synthesized by uterine tissues and increased rates of production occur during labour. The amnion, chorion and decidua all contain mRNA for the newly-discovered inducible form of prostaglandin H synthase (PGHS-2) as well as mRNA for the constitutive form (PGHS-1). Using the reverse transcription polymerase chain reaction (RT-PCR) both mRNAs can be detected during late pregnancy whether women are in labour or not. PGHS-2 protein is detected by Western blot analysis in cells derived from all three tissues. There is regulation of PGHS-2 protein amounts by cytokines, phorbol esters and growth factors. For example, in amnion cells interleukin-1 beta induces a rapid increase in PGHS-2 mRNA levels followed by a decrease to undetectable levels within 4 h of treatment; PGHS-2 protein amounts are also elevated by this treatment. Administration of prostaglandins will induce labour and delivery, whereas inhibition of prostaglandin biosynthesis will delay labour and delivery. Hence, increased prostaglandin production is likely to be a key determinant of the onset and progression of the parturient process.

Amniotic Fluid↗
PubMed1995

Regulation of human decidual cell macrophage inflammatory protein-1 alpha (MIP-1 alpha) production by inflammatory cytokines.

PROBLEM: Inflammation of human gestational tissues is a key pathophysiologic event in the genesis of infection-associated preterm labor. Human gestational tissues produce several inflammatory cytokines after stimulation with bacterial products. These include interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF alpha), and IL-6. Another class of cytokines includes chemokines of the "C-C" subclassification such as macrophage inflammatory protein-1 alpha (MIP-1 alpha). The purpose of this study was to determine whether cultured human decidual cells produce MIP-1 alpha in response to other inflammatory cytokines. METHODS: Various concentrations of IL-1 beta, TNF alpha, IL-6, and IL-4 were incubated with confluent monolayer cultures of decidual cells isolated from normal term placentae for 16 h at 37 degrees C, and MIP-1 alpha concentrations in culture supernatants were measured by ELISA. RESULTS: We found that incubation of decidual cells with IL-1 beta, TNF alpha, and IL-4 resulted in significant concentration-dependent increases in MIP-1 alpha production. IL-6 had no effect on MIP-1 alpha production. CONCLUSIONS: Our data are the first to show that human decidual cells in culture produce MIP-1 alpha in response to other inflammatory cytokines. We suggest that decidual cell production of MIP-1 alpha is an important early event in the pathophysiology of infection-associated preterm labor.

Cells, Cultured↗
PubMed1995

Bacterial lipopolysaccharide-mediated fetal death. Production of a newly recognized form of inducible cyclooxygenase (COX-2) in murine decidua in response to lipopolysaccharide.

Maternal infection is a cause of spontaneous abortion and preterm labor in humans, but the pathophysiology is unclear. We hypothesized that eicosanoids play an important role in infection-driven pregnancy loss. To investigate this hypothesis, we administered lipopolysaccharide (LPS) to pregnant C3H/HeN mice and found that LPS administration caused fetal death in a dose-dependent fashion. Pretreatment with indomethacin significantly decreased the proportion of fetal death from 83% to < 25% in mice injected with 10 micrograms of LPS. Also, decidual explants from LPS-treated mice produced significantly more inflammatory eicosanoids, including prostaglandins E2 and F2 alpha and thromboxane B2, than controls. We investigated the regulatory mechanisms responsible for increased decidual prostanoid production in response to LPS. Western and Northern blots demonstrated that decidual protein and mRNA levels of a recently recognized highly inducible form of cyclooxygenase, COX-2, were substantially increased in mice treated with LPS. Induction of COX-2 was rapid: mRNA was detected 30 min after LPS injection. In contrast, another form of cyclooxygenase, COX-1, was only minimally induced in response to LPS. Our data indicate that LPS induces decidual prostanoid production via increased COX-2 expression. Since LPS-mediated fetal death is markedly diminished by pretreatment with indomethacin, COX-2-mediated eicosanoid production is likely a key pathophysiologic event in LPS-mediated fetal death.

Abortion, Spontaneous↗
PubMed1994

Pre-eclampsia and serum antibodies to oxidised low-density lipoprotein.

Oxidised low-density lipoprotein (Ox-LDL) has been associated with arterial foam-cell formation, and autoantibodies to Ox-LDL are present in human serum. Lipid peroxidation is enhanced in pre-eclampsia. We assessed whether the titre of IgG autoantibody to an epitope of Ox-LDL, malondialdehyde-conjugated low-density lipoprotein (MDA-LDL), was increased in the sera of pre-eclamptic patients. 16 such patients had significantly higher mean titres of autoantibodies to MDA-LDL than healthy pregnant women (p = 0.028). In a multiple regression model, pre-eclamptic patients still had a significantly higher mean titre (p = 0.048). Enhanced lipid peroxidation may be involved in the foam-cell formation of decidua and in the pathogenesis of pre-eclampsia.

Adult↗
PubMed1994

Amniotic fluid prostanoid concentrations increase early during the course of spontaneous labor at term.

OBJECTIVE: The purpose of this study was to determine whether amniotic fluid concentrations of prostanoids increase during spontaneous labor at term. STUDY DESIGN: Amniotic fluid was retrieved transabdominally from 168 patients in spontaneous labor and from 82 patients not in labor. Prostaglandin E2, prostaglandin F2 alpha, 13, 14-dihydro-15-keto-prostaglandin F2 alpha, thromboxane B2, and 6-keto-prostaglandin F1 alpha concentrations were measured with sensitive and specific radioimmunoassays previously validated for amniotic fluid. Statistical analysis was conducted with Kruskal-Wallis analysis of variance, followed by Dunn's test for multiple comparisons. RESULTS: (1) Amniotic fluid concentrations of all prostanoids were significantly higher in patients in early labor (cervical dilatation of < or = 3 cm) than in patients not in labor. (2) The magnitude of the increase in amniotic fluid prostanoid concentrations during early labor was significantly greater for prostaglandin F2 alpha and 13,14-dihydro-15-keto-prostaglandin F2 alpha than for prostaglandin E2, thromboxane B2, and 6-keto-prostaglandin F1 alpha. (3) Patients in the active phase of labor with cervical dilatations between 4 and 7 cm did not have higher prostanoid concentrations than those in early labor (cervical dilatation of < or = 3 cm). (4) A significant increase in amniotic fluid concentrations of prostaglandin F2 alpha and 13,14-dihydro-15-keto-prostaglandin F2 alpha was found in patients with advanced cervical dilatation (8 to 10 cm) in comparison with those in early labor (< 3 cm). CONCLUSION: Amniotic fluid prostanoid concentrations increase early during the course of spontaneous labor at term.

Amniotic Fluid↗
PubMed1994

Protein kinase A interactions with prostaglandin biosynthesis at the chorio-decidual interface.

Activation of the enzyme adenylate cyclase or treatment with dibutyryl cyclic AMP (dbcAMP) stimulates prostaglandin biosynthesis in vitro and in vivo. Prior activation of adenylate cyclase has been shown to inhibit the stimulation of amnion cell prostaglandin E2 (PGE2) biosynthesis by substances such as epidermal growth factor (EGF) and phorbol 12-myristate 13-acetate (PMA). Little is known, however, concerning the effects of activation of the adenylate cyclase system on basal and stimulated prostaglandin biosynthesis in human chorion and decidual cells. Interleukin-1 beta (IL-1 beta), EGF, ionomycin (iono), and PMA are known to stimulate prostaglandin E2 production in human chorion and decidual cells. Hence, we have evaluated the effects of co-treatment of chorion and decidual cells with dbcAMP in the presence and absence of EGF, PMA, IL-1 beta, and iono on prostaglandin production. dbcAMP alone stimulated chorion and decidual PGE2 production. Coincubation of dbcAMP with all four test stimulants resulted in a further enhancement of decidual PGE2 production that was often more than additive. Thus activation of adenylate cyclase can have effects on prostaglandin production that have specificity with respect to tissue source, presence of other stimulants and relative time of exposure of the tissues to each of the substances involved.

Bucladesine↗
PubMed1994

Actions of interleukin-4 on prostaglandin biosynthesis by human amnion cells.

The effects of interleukin-4 (IL-4) on amnion prostaglandin (PG) production have been determined. Human amnion cells from term placentae were grown to confluence and incubated with IL-4 either alone or with various concentrations of epidermal growth factor (EGF) of ionomycin. PGE2 production was determined using a specific radioimmunoassay. IL-4 alone stimulated PGE2 production in amnion cells in a concentration-related manner. IL-4 significantly enhanced the stimulatory actions of ionomycin and EGF on amnion cell PGE2 production. Ionomycin and IL-4 acted synergistically in their effects on PGE2 production by amnion cells whereas EGF and IL-4 acted more additively in this respect. We suggest that IL-4 production by immune effector cells in gestational tissues may contribute to the mechanisms of labor at term and preterm.

Amnion↗
PubMed1994

Regulation of intrauterine prostaglandin biosynthesis: interactions between protein kinase C and interleukin 1 beta.

Activation of protein kinase C with phorbol esters stimulates prostaglandin (PG) biosynthesis in many cell types whereas down-regulation of protein kinase C can suppress stimulatory responses. Interleukin-1 beta (IL-1 beta) can stimulate PG production by intrauterine tissues and may play a significant part in the mechanisms of preterm labor associated with intrauterine infection. Hence we have evaluated the effects of staurosporine and H7 (inhibitors of protein kinase C) on IL-1 beta stimulation of amnion, chorion and decidual prostaglandin E2 (PGE2) production. Staurosporine and H7 alone were without effect on PGE2 production by any cell type. However with minor exceptions both protein kinase C inhibitors enhanced the stimulatory actions of IL-1 beta on PGE2 production by all three cell types. Hence we believe that protein kinase C is closely linked to the regulation of intrauterine PG biosynthesis and that these links may have multiple layers of complexity.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Topographic differences in amniotic fluid concentrations of prostanoids in women in spontaneous labor at term.

These studies were designated to determine if there are differences in prostanoid concentrations between amniotic fluid (AF) retrieved transvaginally from the membrane forebag (lower or forebag compartment) and fluid retrieved by transabdominal amniocentesis from the 'upper compartment' in women in labor. Fluid was retrieved from 53 women in active labor who underwent transabdominal and transvaginal amniocentesis. Fluid was assayed for prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha), 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM), thromboxane B2 (TXB2), and 6-keto-prostaglandin F1 alpha (6-k-PGF1 alpha) using sensitive and specific radioimmunoassays. Concentrations of all prostanoids measured were significantly higher in fluid retrieved by transvaginal than transabdominal amniocentesis; the magnitude of the increase (measured as the ratio of concentrations in the lower/upper compartment) was higher for PGF2 alpha and TXB2 than for the other prostanoids measured; for each prostanoid measured, there was a significant correlation between the concentration in the upper and lower compartment.

Amniocentesis↗
PubMed1994

Lipopolysaccharide-induced fetal death: the role of tumor-necrosis factor alpha.

Lipopolysaccharide (LPS) administration has been known to cause murine fetal death for over 50 years, but the responsible mechanism(s) remains unclear. We used the LPS-hyporesponsive murine strain, C3H/HeJ, to 1) establish whether LPS-induced fetal death is due to a maternal or fetal response to LPS and 2) to investigate the involvement of tumor necrosis factor alpha (TNF alpha) in fetal death caused by LPS. C3H/HeJ (LPS-hyporesponsive) or C3H/HeN (LPS-responsive) females were mated with C57B1/6 or C3H/HeN males (both LPS-responsive). Administration of 10 micrograms LPS caused fetal death in C3H/HeN mothers. However, up to 1000 micrograms LPS did not result in the death of LPS-responsive fetuses when administered to C3H/HeJ mothers. Systemic administration of TNF alpha was able to cause fetal death in both C3H/HeN and C3H/HeJ strains of mice. Pretreatment of pregnant C3H/HeN mice with anti-TNF alpha antibodies significantly reduced fetal death caused by LPS administration. The administration of a sublethal dose of TNF alpha plus 10 micrograms LPS to pregnant C3H/HeJ mice restored abortifacient activity. These results indicate that LPS-induced fetal death is due to a maternal response as opposed to a direct fetal response to LPS and that TNF alpha appears to be an important mediator of fetal death caused by LPS.

Animals↗
PubMed1994

Clinical value of amniotic fluid interleukin-6 determinations in the management of preterm labour.

OBJECTIVE: To ascertain whether the determination of amniotic fluid interleukin-6 (IL-6) concentrations would be a useful clinical test in the management of women with preterm contractions. SETTING: The labour and delivery unit and the Fetal Diagnostic Centre at the University of Utah. SUBJECTS: Pregnant women at various stages of gestation in the third trimester. DESIGN: Amniotic fluid samples were collected from women experiencing one of four clinical scenarios: 1. term pregnancy, not in labour with no evidence of intrauterine infection; 2. normal term labour with no evidence of infection; 3. preterm labour with no evidence of infection and undelivered within one week of sampling; and 4. preterm labour and delivered within seven days of sample collection. Amniotic fluid was obtained by amniocentesis or at the time of amniotomy or hysterotomy. IL-6 in each specimen was determined by a specific rapid ELISA. RESULTS: Amniotic fluid IL-6 levels, given as mean (SEM) in the four groups of women listed were: 1. term pregnancy, not in labour: 20.9 (7.2) pg/ml (n = 60); 2. normal term labour with no infection: 554 (90.7) pg/ml (n = 46); 3. preterm labour with no evidence of infection, undelivered: 47.0 (17.2) pg/ml (n = 35); and 4. preterm labour, delivered: 456.7 (101.7) pg/ml (n = 40). There was no significant difference in the means of amniotic fluid IL-6 for the term labour and preterm labour delivered groups. In general, amniotic fluid IL-6 levels during term labour increased with advancing cervical dilation. There was no correlation of cervical dilation and amniotic fluid IL-6 levels in women having preterm delivery. Receiver-operator curves revealed optimal IL-6 levels for discrimination of labour at term to be 50 pg/ml and for preterm delivery to be 200 pg/ml. CONCLUSIONS: IL-6 can readily be detected in the amniotic fluid of most women who are in active labour, regardless of gestational age. Our data suggest that amniotic fluid IL-6 determinations may be clinically useful in the management of preterm labour.

Adult↗
PubMed1994

Interleukin-1 receptor antagonist (IL-1ra) production by human amnion, chorion, and decidua.

PROBLEM: This study was conducted to determine whether (1) conditioned media from unstimulated primary cultures of human amnion, chorion, or decidua contain detectable concentrations of IL-1ra in vitro, and (2) bacterial endotoxin (LPS), tumor necrosis factor-alpha (TNF-alpha), or IL-1-beta (IL-1 beta) stimulate amnion, chorion, or decidua to produce increased amounts of IL-1ra. METHOD: Placentae were obtained from women at term with intact membranes before the onset of labor. Amnion, chorion, and decidual cells were isolated by standard procedures and grown to confluence. Cells were then cultured in quadruplicate for 16 h in tissue culture medium supplemented with 10% fetal calf serum or, additionally, with various concentrations of Escherichia coli LPS, TNF-alpha, or IL-1 beta. Culture supernatants were collected, and concentrations of IL-1ra were quantitated by a sensitive and specific enzyme-linked immunosorbent assay for IL-1ra. RESULTS: Results showed that primary cultures of amnion and chorion from 4 of 9 and decidua from 10 of 12 placentae had detectable rates of production of IL-1ra (ranges: 0.08-6.5, 0.42-12.1, and 1.55-96.5 pg IL-1ra/microgram protein/16 h, respectively). In addition, LPS (10-1,000 ng/ml) and IL-1 beta (0.1-10 ng/ml), but not TNF-alpha (0.01-100 ng/ml), stimulated decidual cells to release/secrete increased amounts of IL-1ra compared with media alone (range: 2.5-400 pg IL-1ra/microgram protein/16 h, P < 0.0001). In contrast, neither LPS, TNF-alpha, or IL-1 beta could stimulate amnion or chorion to release/secrete IL-1ra. CONCLUSIONS: These results indicate (1) that amnion, chorion, and predominantly decidua, can release or secrete IL-1ra in vitro, and (2) that LPS and IL-1 beta can stimulate decidual cells to produce increased amounts of IL-1ra.

Amnion↗
PubMed1994

Arachidonate lipoxygenase metabolite formation in gestational tissues.

Products of arachidonic acid metabolism via the lipoxygenase pathways have a potential role in the onset of human labor. We have determined whether activation of protein kinase C can modulate the rate of biosynthesis within the uterus of five important arachidonate lipoxygenase metabolites, i.e., leukotriene B4 (LTB4), LTC4, 5-hydroxyeicosatetraenoic acid (5-HETE), 12-HETE and 15-HETE. Amnion, chorion laeve and decidual cells were isolated, grown to confluence and incubated with phorbol 12-myristate 13-acetate (PMA). PMA caused concentration-related stimulation of 5-HETE, 12-HETE and 15-HETE (but not LTB4) production; there were some stimulatory actions on decidual and amnion (but not chorion) LTC4 production. We postulate that activation of protein kinase C can result in enhanced production of arachidonate lipoxygenase metabolites that may have actions on the parturient process.

Amnion↗
PubMed1993

Adaptive immune responses during murine pregnancy: pregnancy-induced regulation of lymphokine production by activated T lymphocytes.

OBJECTIVE: We hypothesized that the lymphokine production by splenocytes and decidual lymphocytes would be altered because of changes in immunoregulation during pregnancy. STUDY DESIGN: Splenocytes and decidual lymphocytes were isolated from syngeneic and allogeneic pregnant mice at different times of gestation. The lymphocytes (10(7) cells/ml) were stimulated with anti-CD3 antibody, and culture supernatants were assayed for several lymphokines, including interleukin-2, interferon-gamma, interleukin-4, interleukin-6, granulocyte-macrophage colony-stimulating factor, and interleukin-3. Statistical analysis was by analysis of variance or paired t test. RESULTS: Activated splenocytes produced significantly less interleukin-2 and more interleukin-4, interleukin-6, and interleukin-3 as murine pregnancy advanced. Production of interferon-gamma and granulocyte macrophage colony-stimulating factor by activated splenocytes peaked in the first 8 to 14 days of pregnancy. Stimulated decidual lymphocytes produced modest amounts of interleukin-6, granulocyte-macrophage colony-stimulating factor, and interleukin-3 during pregnancy but no interleukin-2, interferon-gamma, or interleukin-4. Similar results were found for both syngeneic and allogeneic matings. CONCLUSIONS: Our findings indicate that splenocyte lymphokine production favors interleukin-4 production over interleukin-2 production. This finding suggests that antibody production would be enhanced and cytotoxic cellular immune responses inhibited during pregnancy. These changes occurred regardless of mating partner, suggesting that the specific antigenic stimulus during normal pregnancy does not regulate lymphokine production. Activated splenocytes and decidual lymphocytes were found to differ in their capacity to produce lymphokines, indicating that the decidua constitutes a distinct and unique immunologic microenvironment.

Animals↗
PubMed1993

Regulation of fetal fibronectin production in human chorion cells.

OBJECTIVE: Our purpose was to evaluate the role of human chorion in production of fetal fibronectin and to assess the regulation of fetal fibronectin production by inflammatory products and cytokines. STUDY DESIGN: Human chorion cells were grown in culture, and at confluence cells were incubated with and without lipopolysaccharide, interleukin-1 beta, tumor necrosis factor-alpha, and acetylsalicylic acid. Fetal fibronectin production was measured in the supernatants by means of enzyme-linked immunosorbent assay. RESULTS: Production of fetal fibronectin was increased by lipopolysaccharide, interleukin-1 beta, and tumor necrosis factor-alpha. Acetylsalicylic acid had no effect on fetal fibronectin biosynthesis. CONCLUSIONS: Fetal fibronectin production by human chorion cells in vitro is stimulated by inflammatory products and mediators, which are considered to be important in the initiation of some cases of preterm labor.

Cells, Cultured↗