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Biomedical subjects

D W Branch

Publications and source records attributed to D W Branch.

At least 91 records · Page 5Linked to original sources
PubMed1993

Induction of endothelial cell tissue factor activity by sera from patients with antiphospholipid syndrome: a possible mechanism of thrombosis.

OBJECTIVE: The hypothesis of our study is that antiphospholipid antibodies predispose to thrombosis by inducing endothelial cell tissue factor expression. STUDY DESIGN: Monolayers of cultured human umbilical vein endothelial cells were incubated for 8 hours in a medium containing 20% serum obtained either from patients with antiphospholipid antibodies (n = 11) or normal subjects (n = 8). Similar incubations were performed with immunoglobulin G fractions from either patients with antiphospholipid antibodies (n = 3) or normal subjects (n = 3). Endothelial cell tissue factor expression was measured with a tissue factor-specific chromogenic substrate assay. The results were analyzed with a two-tailed t test. RESULTS: The mean endothelial cell tissue factor expression induced by antiphospholipid sera was significantly greater than the controls (p < 0.02). Immunoglobulin experiments indicated that the factor(s) responsible for the induction of tissue factor expression resides in the immunoglobulin G fraction of the sera (p < 0.01). CONCLUSIONS: Endothelial cell tissue factor expression is induced by antiphospholipid sera, with activity residing at least in part in the immunoglobulin fraction. The induction of tissue factor by antiphospholipid sera may play a role in the thrombotic tendency observed in patients with antiphospholipid syndrome.

Antibodies, Antiphospholipid↗
PubMed1993

A murine model of preterm labor: inflammatory mediators regulate the production of prostaglandin E2 and interleukin-6 by murine decidua.

Inflammatory processes may be important in the initiation and propagation of uterine contractions and preterm labor in human pregnancies. Recently, a murine model of preterm labor has been described. The purpose of our study was to determine whether murine decidua responds to inflammatory mediators, such as lipopolysaccharide (LPS) and the inflammatory cytokines interleukin (IL)-1 beta and tumor necrosis factor (TNF). Allogeneic pregnant mice (C3H/Hen females mated with C57/B6 males) were killed at 12-14 days of pregnancy, decidual tissue was isolated, and explants were placed on the polycarbonate membrane of Costar Transwell inserts. Initial validation studies of this explant system, including biochemical and histologic evaluations, indicated that the decidual tissue remained intact, viable, and responsive to IL-1 beta for at least 5 days in explant culture. Treatment of murine decidual explants with LPS, IL-1 beta, and TNF resulted in significant increases in the production of prostaglandin E2 (PGE2) and IL-6. Thus the regulation of PGE2 and IL-6 production from murine decidua by LPS and inflammatory cytokines is similar to findings previously reported for human decidua. Our findings are consistent with the view that the pathophysiology of infection-induced preterm labor in the mouse may be similar to that in human pregnancy and supports the continued development of murine models of preterm labor.

Animals↗
PubMed1993

Are immunoglobulins with lupus anticoagulant activity specific for phospholipids?

Recent studies have suggested that the lupus anticoagulant (LA) may be specific for prothrombin, prothrombin-phospholipid complexes, or beta 2 glycoprotein 1 (beta 2GP1) rather than phospholipids. We performed a series of experiments to determine whether LA is indeed phospholipid specific. IgG was purified from sera of six patients with the antiphospholipid syndrome (APS) and 10 healthy controls. The six IgG-APS preparations had both LA and anticardiolipin (aCL) activity. Incubation of the six IgG-APS preparations with cardiolipin (CL), phosphatidylserine (PS), phosphatidylcholine (PC), or PS/PC (20:80) liposomes in Tris-buffered saline, resulted in loss of LA activity from the supernatant. We postulated that loss of activity might have resulted from absorption of IgG LA antibodies by phospholipids, a dilutional effect, or the presence of phospholipids in the supernatant causing 'by-pass' of IgG LA inhibitory activity. To distinguish between these possibilities, we re-isolated IgG from the supernatants and re-tested them for LA activity. IgG re-isolated from the PS. CL and PS/PC supernatants had no LA activity, but LA activity remained in the PC supernatant. This suggested that IgG with LA activity was absorbed by negatively charged but not by zwitterionic phospholipids. In like manner, PS, CL and PS/PC, but not PC liposomes, absorbed IgG with aCL activity. Mixtures of the phospholipid liposomes with beta 2GP1 did not modify the absorption of IgG with LA or aCL activity. Finally, we demonstrated that IgG eluted from immunoglobulin-cardiolipin liposome complexes had LA activity. Based on these findings, we conclude that at least one population of antibodies with LA activity is phospholipid specific.

Antibodies, Anticardiolipin↗
PubMed1992

Repeated fetal losses associated with antiphospholipid antibodies: a collaborative randomized trial comparing prednisone with low-dose heparin treatment.

OBJECTIVE: We attempted to compare the use of low-dose heparin with a standard dose of 40 mg prednisone daily (both plus low-dose aspirin) for treatment of pregnant women with antiphospholipid antibody-associated recurrent fetal loss with respect to maternal and perinatal morbidity and efficacy in prevention of fetal death. STUDY DESIGN: A multicenter randomized trial included 20 patients. Generalizability of results from randomized patients was evaluated by means of additional data from 13 women refusing and 12 women ineligible for randomization. Data from study groups were compared with Fisher's exact test, and generalizability was evaluated with a chi 2 test for trend. RESULTS: Live birth rates were the same (75%) with either treatment, but "serious" maternal morbidity and the frequency of preterm delivery were significantly higher among women randomly assigned to prednisone (p = 0.02 vs p = 0.006). Preterm delivery among prednisone-treated women was usually associated with premature rupture of the membranes or preeclampsia. These results could be generalized to the other groups of women ascertained during the course of the study. CONCLUSIONS: Low-dose heparin should be preferred to prednisone when treatment is indicated for high-risk pregnant women with antiphospholipid antibodies.

Abortion, Habitual↗
PubMed1992

A human endometrial explant system: validation and potential applications.

OBJECTIVE: Our objective was to describe an in vitro explant system to study the regulation of prostaglandin production by human endometrium. STUDY DESIGN: Segments of late-luteal-phase endometrium were obtained aseptically at the time of endometrial sampling. The endometrium was cut into 1 mm3 pieces and applied to the polycarbonate membrane of tissue-culture-well inserts for 12-well plates (Costar Transwell cell culture chamber inserts, 0.4 microns pore size). After placing the well inserts, culture medium was carefully applied. The explants were incubated at 37 degrees C in 5% carbon dioxide in air, and the culture medium was changed daily. RESULTS: Electron microscopic examination and lactate dehydrogenase determinations of the explants revealed cellular viability for < or = 5 days of culture. Endometrial explants responded to treatment with interleukin-1 beta and tumor necrosis factor by a concentration-dependent increase in the production of prostaglandin E2. Costimulation of late luteal endometrial explants with interleukin-1 beta (10 ng/ml) and progesterone (10(-6) mol/L) resulted in variable production of prostaglandin E2, suggesting that the histologic examination of the endometrium does not necessarily reflect the functional properties of the endometrium. CONCLUSIONS: Our data show that when used with human endometrial tissue this explant system maintains tissue viability and responsiveness for < or = 5 days. This approach to explant methods is simple and provides a flexible model to study the regulation of the production of bioactive substances by human endometrial tissue.

Culture Techniques↗
PubMed1992

Sera from preeclamptic patients contain factor(s) that stimulate prostacyclin production by human endothelial cells.

A relative decrease in endothelial cell prostacyclin production may be pivotal in the genesis of preeclampsia. We determined the effect of sera from preeclamptic women on prostacyclin production by monolayers of normal term human umbilical vein endothelial cells. Endothelial cells were incubated with media containing serum from patients with preeclampsia, non-hypertensive, gestational age-matched pregnant controls, or normal non-pregnant controls (N = 7, all groups). 6-Keto-prostaglandin F1 alpha, the stable metabolite of prostacyclin, was measured directly in the culture medium by radioimmunoassay. Treatment with preeclamptic sera, when associated with a statistically significant increase in prostacyclin metabolite production by endothelial cells. Thus, sera from women with preeclampsia stimulate rather than inhibit prostacyclin production by endothelial cells. We speculate that there is a factor in the sera of women with preeclampsia that functions to activate endothelial cells or which may play a role in the homeostatic mechanisms to balance reduced prostacyclin output in preeclampsia.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

The preparation of a sensitive partial thromboplastin reagent from bovine brain.

Commercial partial thromboplastin reagents markedly differ in their sensitivity to factor deficiency, heparin, or the lupus anticoagulant. These differences may be partly due to the variable phospholipid content of different commercially available reagents. For over 15 years, we have routinely used a partial thromboplastin prepared from human brain. In the past four years, we have been using a similarly prepared bovine partial thromboplastin reagent. This report describes the preparation of our partial thromboplastin reagent, as well as an analysis of the phospholipid composition of both the human and bovine thromboplastin reagents. Four separate brain preparations produced consistent percentages of the anionic phospholipids, phosphatidylserine, and phosphatidylinositol. The bovine reagent was also compared with commercial partial thromboplastin reagents in the detection of coagulation factor deficiency, heparin, and the lupus anticoagulant.

Animals↗
PubMed1992

The regulation of endothelin production in human umbilical vein endothelial cells: unique inhibitory action of calcium ionophores.

Endothelins (ETs) are a recently discovered family of small proteins that have potent long-lasting vasoconstrictive activities. Increased circulating concentrations of ETs have been found in hypertensive and renal disorders, including pregnancy-induced hypertension (PIH). PIH has been postulated to be the end result of endothelial cell damage and aberrant calcium metabolism. We evaluated the effects of calcium ionophores, calcium channel blockers, and two forms of cellular damage on ET production by human umbilical vein endothelial cells (HUVEC). Cells were grown to confluence and then incubated for 16 h with these treatments: physical trauma ("scratching"), oxidant damage (hydrogen peroxide, 1-20 mM), ionomycin (0.25-2.0 microM), A-23187 (10(-9)-10(-5) M), verapamil (0.22-22.0 microM), and nifedipine (2-200 micrograms/mL). ET production was determined using a commercial RIA that detects ET-1 and ET-2. Physical trauma enhanced ET production, whereas oxidant damage had the opposite effect. Both ionomycin and A-23187 caused concentration-dependent inhibition of ET production. Neither verapamil nor nifedipine consistently altered ET production. We conclude that specific forms of cellular damage can stimulate HUVEC ET production, although oxidant damage may be slightly inhibitory. Thus, enhanced ET levels in PIH may represent endothelial cell activation, rather than damage. HUVEC ET production is regulated in an inverse manner by intracellular calcium concentrations, suggesting a negative feedback from mediators of ET action on cells.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Outcome of children born to women treated during pregnancy for the antiphospholipid syndrome.

OBJECTIVE: To determine the rate of neonatal and childhood medical complications in the offspring of women with the antiphospholipid syndrome who are treated during pregnancy. METHODS: We compared 29 infants born to 23 mothers with antiphospholipid syndrome with a group of control children matched for year and gestational age at birth and route of delivery. During pregnancy, mothers with antiphospholipid syndrome were treated with accepted therapeutic regimens, including prednisone and low-dose aspirin, heparin and low-dose aspirin, and others. RESULTS: Neonatal complications in the study infants included hyperbilirubinemia (14), respiratory distress syndrome (three), bronchopulmonary dysplasia (two), necrotizing enterocolitis (two), intraventricular hemorrhage (two), neonatal sepsis (one), coarctation of the aorta (one), hypothyroidism (one), hypoglycemia (one), and death (one). Two children had feeding problems, four had delayed psychomotor development, and eight were small for their age. However, the overall rate of neonatal or childhood complications did not differ from that in the control children. CONCLUSIONS: Our data indicate that prematurity and neonatal problems are common, but the childhood course for these offspring is similar to that of other premature infants.

Antiphospholipid Syndrome↗
PubMed1992

Outcome of treated pregnancies in women with antiphospholipid syndrome: an update of the Utah experience.

OBJECTIVE: To determine the outcome of treated pregnancies in women with well-characterized antiphospholipid syndrome. METHODS: We reviewed 82 consecutive pregnancies in 54 women with antiphospholipid syndrome who were treated during pregnancy with the following: 1) prednisone and low-dose aspirin; 2) heparin and low-dose aspirin; 3) prednisone, heparin, and low-dose aspirin; or 4) other combinations of these medications or immunoglobulin. RESULTS: The overall neonatal survival rate was 73%, excluding spontaneous abortions, but treatment failures (fetal and neonatal deaths) occurred in all treatment groups. Patients with successful treated pregnancies had fewer previous fetal deaths than those with unsuccessful treated pregnancies. There were no significant differences in outcome among the four treatment groups. Preeclampsia and fetal distress occurred in half of all pregnancies, and fetal growth impairment occurred in nearly one-third. Preterm delivery due to maternal or fetal indications was required in 37% of the pregnancies. Four pregnancies were also complicated by postpartum thrombosis during treatment. CONCLUSIONS: Pregnancy in women with antiphospholipid syndrome appears to be improved by treatment, but fetal loss may occur despite treatment. Preeclampsia, fetal distress, fetal growth impairment, and premature delivery are common. Because of the clinically significant risk of thrombotic episodes, thrombosis prophylaxis should be considered in these patients.

Antiphospholipid Syndrome↗
PubMed1991

Preliminary evidence for homoeostatic mechanism regulating endothelin production in pre-eclampsia.

To find out whether a serum factor in pre-eclamptic women is the cause of the raised serum endothelin concentrations associated with the disorder, the effect of serum from pre-eclamptic women on endothelin production by endothelial cells was compared with that of serum from pregnant and non-pregnant controls. The finding that pre-eclamptic serum suppresses endothelin production suggests that it contains a factor that might be part of a homoeostatic response to raised serum endothelin concentrations in pre-eclampsia.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Lymphokine production during term human pregnancy: differences between peripheral leukocytes and decidual cells.

Although the fetus is considered to be an "allograft" there is little information concerning the role of lymphokines in human pregnancy. Lymphokines are polypeptides secreted by stimulated lymphocytes that direct the immune response by enabling immune effector cells to communicate with each other. To characterize lymphokine production during normal human pregnancy, we isolated peripheral leukocytes and decidual lymphocyte-like cells from women undergoing repeat cesarean section at term. After stimulation with mitogen and paternal antigen for 24 hours, culture supernatants were assayed for granulocyte-macrophage colony-stimulating factor and interleukin-2 by enzyme-linked immunosorbent assay. There was no difference in the amount of interleukin-2 produced by stimulated peripheral and decidual cells. However, granulocyte-macrophage colony-stimulating factor production by stimulated decidual lymphocyte-like cells was significantly greater than granulocyte-macrophage colony-stimulating factor produced by peripheral lymphocytes. Decidual lymphocyte-like cells produced granulocyte-macrophage colony-stimulating factor both spontaneously and after stimulation with mitogen or paternal antigen, whereas peripheral leukocytes did not. This suggests that the decidua constitutes a distinct immunologic microenvironment.

Cells, Cultured↗
PubMed1990

Antiphospholipid antibodies and recurrent pregnancy loss: correlation between the activated partial thromboplastin time and antibodies against phosphatidylserine and cardiolipin.

Concordance was determined among the presence of the lupus anticoagulant measured by prolongation of the activated partial thromboplastin time and IgG and IgM antibodies against phosphatidylserine and cardiolipin in 47 patients selected for study because of histories of recurrent spontaneous pregnancy loss and a positive test for at least one antiphospholipid antibody. Forty-five of 47 patients (96%) had a prolonged activated partial thromboplastin time, ranging from 46 to 150 seconds. Elevated levels of IgG antiphosphatidylserine antibodies and IgM antiphosphatidylserine antibodies were present in 41 (87%) and in 19 (40%) of samples, respectively. Antibodies against cardiolipin were less commonly observed; IgG anticardiolipin antibodies in only 32 (68%) of 47 samples and IgM anticardiolipin antibodies in 15 (36%) of 42 samples. Neither the level of IgG antiphosphatidylserine antibodies nor the level of IgG anticardiolipin antibodies correlated well with the degree of prolongation of coagulation in the activated partial thromboplastin time (R = 0.312, p = 0.032 for IgG antiphosphatidylserine antibodies versus activated partial thromboplastin time; R = 0.251, p = 0.088 for IgG anticardiolipin antibodies versus activated partial thromboplastin time). Concordance with the activated partial thromboplastin time, however, was observed in 41 (87%) samples for IgG antiphosphatidylserine antibodies and in only 32 (68%) samples for IgG anticardiolipin antibodies. Our conclusion is that the antiphosphatidylserine assay correlates best, although not totally, with the presence of lupus anticoagulant and that the antiphosphatidylserine assay is more sensitive than testing for anticardiolipin.

Abortion, Habitual↗