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J S Alexander

Publications and source records attributed to J S Alexander.

85 records · Page 5Linked to original sources
PubMed1988

Phalloidin enhances endothelial barrier function and reduces inflammatory permeability in vitro.

Phalloidin, a potent microfilament toxin, induces polymerization of actin in vitro and in vivo. In a permeability assay, bovine aortic endothelial cell cultured on microcarrier beads exclude significantly more serum albumin after 30 min treatment with 10(-6), 10(-8), and 10(-10) M phalloidin than controls. Furthermore, pretreatment of microcarriers with 10(-8) M phalloidin significantly reduces permeability increases by histamine, bradykinin, thromboxane A2 mimetic, and cytochalasin B, (all at 10(-6) M). Phalloidin also causes significant surface area and perimeter increases in cultured endothelial cells. The cells also display increased acting stress fibers and show a weblike cytoskeletal pattern of microfilaments. These data suggest that in vitro the endothelial junctional barrier may be enhanced in part by assembly of actin filaments.

Animals↗
PubMed1988

Detection and titration of class-specific antisperm antibodies in serum using an enzyme-linked immunosorbent assay.

An antisperm antibody enzyme-linked immunosorbent assay (ELISA) that uses whole unfixed sperm and detects immunoglobulin G (IgG) and IgA antibodies in serum was developed. Donor sperm were washed and plated on poly-L-lysine-treated microtiter plates. The patient's sera were diluted to concentrations of 1:4 to 1:256 and incubated with sperm. Positive and negative sera had been previously tested for IgG antisperm antibody activity with a radiolabeled antiglobulin assay. Samples were considered positive when the mean absorbance of triplicate wells was greater than 2 SD above the pooled negative mean. Intra-assay variation was 7.9 and 9.6% for pooled negative and positive controls, respectively. Identical titers of control positive serum were consistently detected. A correlation of 0.83 was observed between ELISA IgG serum titers and radiolabeled antiglobulin results (N = 12). All negative samples tested negative in both assays (N = 21). Some serum samples showed IgA antisperm antibodies. Determination and titration of class-specific antibodies in serum should facilitate initial screening and follow-up of patients at risk for antisperm antibodies.

Enzyme-Linked Immunosorbent Assay↗
PubMed1987

Serotonin induced actin polymerization and association with cytoskeletal elements in cultured bovine aortic endothelium.

Serotonin, (5-hydroxytryptamine, 5-HT) binds to cultured endothelial cell stress fibers as identified by fluorescence microscopy and in vitro induces actin polymerization as measured by DNase 1 inhibition and differential centrifugation; the structural change in actin in the presence of 5-HT resembles actin paracrystals as visualized by negative staining under electron microscopy. These observations indicate that 5-HT, which is taken up by endothelium by a non-mediated diffusion, may interact directly with actin to affect cytoskeletal changes.

Actins↗
PubMed1985

Gonadotrophic regulation of prolactin mediated progesterone secretion in vitro.

The effects of preincubating rat granulosa cells with FSH, LH, and Prl on subsequent Prl mediated progesterone secretion were investigated. Granulosa cells were isolated from ovarian follicles 50 h after injection of 5 IU PMSG and were then plated on poly-L-lysine coated coverslips in serum supplemented medium. Cells were preincubated for 24 h in the absence of hormones (control) or with the addition of either 0.25, 2.5, 25 ng/ml rat FSH or rat LH, or 1 microgram/ml rat Prl. Following the preincubation period, cells were maintained for an additional 6 or 8 days in the presence or absence of 1 microgram/ml Prl. When cells were preincubated with FSH or LH, only the two higher concentrations (2.5 and 25 ng/ml) stimulated significantly more progesterone secretion than control cultures during the 24 h preincubation period. For each series of preincubations, cells cultured for 6 or 8 days in the presence of Prl secreted significantly more progesterone at each day of culture than cells cultured without Prl. Cells preincubated and cultured with Prl secreted only 3-7-fold more progesterone than cells preincubated in control medium and then cultured with Prl. Preincubation with FSH or LH promoted a 20-45-fold increase in Prl mediated progesterone secretion compared to control preincubation cultures that also subsequently were cultured with Prl. The magnitude of Prl mediated progesterone secretion observed through 6 days of culturing was dose dependent on the preincubation concentration of FSH or LH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Modulation of prolactin mediated progesterone secretion by gonadotrophin subunits.

The effects of preincubating rat granulosa cells with porcine LH, and its dissociated alpha and beta subunits on subsequent Prl mediated progesterone secretion were examined. Granulosa cells were isolated from ovarian follicles 50 h after injection of 5 IU PMSG and were then cultured as monolayers in serum supplemented medium. Cells were preincubated for 24 h with medium alone (control) or with 0.1 or 1 microgram/ml of LH, LH alpha, LH beta, or both LH alpha and LH beta. Cells were also preincubated with 50 ng/ml LH alpha and 50 ng/ml LH alpha that had been further purified with immunoaffinity chromatography. Following the preincubation period, cells were maintained an additional 6 days in the presence or absence of 1 microgram/ml Prl. Preincubation with LH or its individual subunits markedly increased the responsiveness to Prl stimulation through 6 days of culture, whereas cells cultured in the absence of Prl secreted decreasing amounts of progesterone. Preincubation with the dissociated subunits increased Prl mediated progesterone secretion approximately two-thirds as much as preincubation with intact pLH. Immunopurified pLH alpha increased the responsiveness to Prl to the same degree as non-purified pLH alpha, suggesting that the stimulatory effects of the subunits are not due to contamination by intact LH. The magnitude of Prl mediated progesterone secretion was dependent upon the preincubation concentration of LH or its dissociated subunits in most, but not all treatments. The increased responsiveness to Prl suggests that in the proper endocrine environment, individual subunits of gonadotrophins may functionally interact with target cells.

Animals↗
PubMed1981

Optimal conditions for the study of surface topography of granulosa cell cultures.

The purpose of this study was to define optimal substrate conditions for permitting correlation of cell surface morphology with progesterone secretion by luteinized granulosa cells in vitro. Some 3-5 x 10(5) granulosa cells were obtained from preovulatory follicles of PMS-LH treated rats and plated upon carbon, poly-L-lysine or collagen-coated glass coverslips within plastic multiwells or upon Cytodex, Biosilon or poly-L-lysine coated Sephadex beads within siliconized glass roller tubes. Cells were maintained at 36.5 degrees C in 1.0 ml medium with and without 1.0 microgram purified prolactin (r, bPRL). Spent medium was assayed for progesterone by RIA. Cultures were processed for SEM observation of cell surface features. Results indicate that: 1) cells cultured in multiwells upon carbon, poly-L-lysine or glass grow as flattened monolayers but demonstrate considerable tearing distortion following routine processing for SEM, 2) cells cultured upon collagen-coated coverslips or microcarriers within roller tubes maintain a more spherical shape, exhibit the least distortion of surface fine structure and secrete increased amounts of progesterone in the presence of PRL. It is concluded that the use of Cytodex microcarriers for culturing granulosa cells permits optimal conditions for both progesterone secretion and maintenance of surface morphology.

Animals↗
PubMedDate not supplied

Protease chymotrypsin mediates the endothelial expression of P- and E-selectin, but not ICAM and VCAM, induced by placental trophoblasts from pre-eclamptic pregnancies.

OBJECTIVES: Soluble endothelial-cell adhesion molecules (ICAM, VCAM and PECAM) are markers of endothelial activation, and are elevated in the maternal circulation during pregnancy and even further increased in pregnancies complicated by pre-eclampsia (PE). To identify possible sources of endothelial activators during pregnancy, we addressed whether factors released from placental trophoblast cells (TCs) activate endothelial cells (ECs) to enhance adhesion molecule expression on ECs. We also examined whether proteases released by placental cells induce the endothelial cell surface molecule expression in PE. METHODS: Confluent ECs were co-cultured with placental TCs derived from normal (n=9) or PE (n=8) pregnancies or with placental conditioned media (CM) derived from PE placental cultures (n=7). ICAM, VCAM, P-selectin and E-selectin were quantified using an enzyme-linked immunosorbent assay (ELISA). The protease inhibitors alpha(2)-macroglobulin (alpha(2)M), thrombin inhibitor (TI) and chymotrypsin inhibitor (CI) were tested in the co-culture system. mRNAs for ICAM, VCAM, P-selectin and E-selectin were determined by RNase protection assay (RPA). NF-kappaB activity in ECs was also determined. RESULTS: (1) ICAM and VCAM expression was significantly increased on ECs co-cultured with both normal-TCs and PE-TCs, compared to control ECs (P<0.01). ICAM and VCAM expression in ECs co-cultured with normal-TCs did not differ from ECs co-cultured with PE-TCs. (2) E-selectin expression was increased on ECs co-cultured with normal-TCs (P<0.05) and further increased in ECs co-cultured with PE-TCs (P<0.01). (3) P-selectin expression was increased on ECs co-cultured with PE-TCs, but not ECs co-cultured with normal-TCs compared to control ECs (P<0.05). (4) alpha(2)M and TI did not alter the ICAM, VCAM, P-selectin and E-selectin expression on ECs induced by PE-CM. (5) CI blocked the upregulation of P-selectin and E-selectin (P<0.05), but not ICAM and VCAM expression, in ECs cultured with PE-CM. (6) Changes in mRNA for ICAM, VCAM, P-selectin and E-selectin paralleled the increases in protein expression on ECs cultured with PE-CM. (7) NF-kappaB activity was also increased in cells challenged with PE-CM. CONCLUSIONS: (1) Factor(s) released from both normal-TCs and PE-TCs promote ICAM and VCAM expression on ECs. (2) Factor(s) released from PE-TCs significantly increase EC P-selectin and E-selectin expression. (3) CI blocks the upregulation of P-selectin and E-selectin on ECs induced by factors released from PE placental cells, suggesting that chymotrypsin is responsible for the increased endothelial expression of P-selectin and E-selectin in pre-eclampsia.

Cell Adhesion Molecules↗
PubMedDate not supplied

Activation of endothelial cells in preeclampsia: increased neutrophil-endothelial adhesion correlates with up-regulation of adhesion molecule P-selectin in human umbilical vein endothelial cells isolated from preeclampsia.

OBJECTIVE: Increased endothelial activation has been suggested to be important in the pathophysiology for preeclampsia. Our objective was to examine whether in preeclampsia neutrophil adherence to endothelial cells is increased and whether endothelial cell-surface adhesion molecule expression is up-regulated. METHODS: Endothelial cells were isolated from normal (n = 10) and preeclamptic (n = 9) human umbilical veins (HUVECs). Neutrophils were isolated from normal, healthy, nonpregnant female volunteers. Freshly isolated neutrophils were labeled with 51Cr, and labeled neutrophils were coincubated with confluent normal and preeclamptic endothelial monolayers. Adhesion assays were then performed. To determine whether in preeclampsia endothelial cellular-surface adhesion molecules are responsible for increased neutrophil-endothelial adhesion, cellular adhesion molecule expression of P-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1), and E-selectin were examined by an enzyme-linked binding assay. Furthermore, adhesion assays were also performed on HUVECs pretreated with antibodies against P-selectin, ICAM-1, VCAM-1, and E-selectin. RESULTS: Neutrophil adhesion to the HUVECs from preeclamptic pregnancies was significantly increased compared with neutrophil adhesion to the HUVECs from normal pregnancies (P < .01). Expression of cellular-surface adhesion molecule of P-selectin was significantly higher (P < .01) and ICAM-1 was significantly lower (P < .05) in HUVECs isolated from preeclampsia than from normal controls, whereas there was no difference for VCAM-1 and E-selectin expression between HUVECs from normal and preeclamptic pregnancies. No differences were found for neutrophil-endothelial adhesion on normal HUVECs pretreated with anti-P-selectin, anti-ICAM-1, anti-VCAM-1, and anti-E-selectin compared with the untreated cells. However, pretreatment of preeclampsia HUVECs with anti-P-selectin, anti-ICAM-1, anti-VCAM-1, and anti-E-selectin completely or partially blocked the neutrophil-endothelial adhesion compared to the untreated cells. CONCLUSION: There is a significant increase in neutrophil adhesion to HUVECs that are isolated from preeclamptic pregnancies compared with normal controls. This increase appears to be a result of up-regulation of the cell-surface adhesion molecule P-selectin. Elevated P-selectin expression may play a significant role in neutrophil-endothelial hyperadhesiveness and contribute to vascular complications associated with preeclampsia.

Antibodies↗
PubMedDate not supplied

Increased neutrophil-endothelial adhesion induced by placental factors is mediated by platelet-activating factor in preeclampsia.

OBJECTIVE: Endothelial cell activation or dysfunction and neutrophil-endothelial cell adhesion have been suggested to be important in the pathophysiology of preeclampsia. However, the mechanisms that underlie the alteration of endothelial cell function in preeclampsia are unknown. Placenta from preeclamptic pregnancies produces mediators and autacoids, which may be released into the maternal circulation and modulate endothelial function. In this study, the effect of placental factor(s) on neutrophil-endothelial adhesion and the possible role of platelet-activating factor (PAF) in mediating the response have been examined. METHODS: Endothelial cells were isolated from human umbilical veins (HUVECs) from normal pregnancies. Confluent primary passage HUVECs were exposed to conditioned medium derived from normal and preeclamptic placental tissue cultures, with unconditioned medium as a control. Placental-conditioned medium was prepared by incubation of placental whole villous tissue in Dulbecco's Modified Eagle's Medium (DMEM) for 48 hours. Neutrophil-endothelial adhesion assays were performed to evaluate placental factors in mediating neutrophil-endothelial adhesion, and a PAF-3H scintillation proximity assay (SPA) system was used to determine endothelial PAF production. The PAF-receptor antagonist WEB 2086 was used to block placental factor-mediated increased neutrophil-endothelial adhesion induced by conditioned medium derived from preeclamptic placenta. RESULTS: Neutrophils were significantly more adherent to HUVECs treated with conditioned medium from preeclamptic placentas (28.44 +/- 2.47%) than to HUVECs treated with conditioned medium from normal placentas (18.95 +/- 1.57%) or with unconditioned medium (14.60 +/- 1.29%, P < .01). Also, HUVECs exposed to preeclamptic placental-conditioned medium produced more PAF than the cells exposed to normal conditioned medium and unconditioned medium, 416.18 +/- 17.14 pg/1 x 10(7) cells versus 330.90 +/- 35.70 and 296.43 +/- 44.40 pg/1 x 10(7) cells, P < .05, respectively. The PAF receptor antagonist WEB 2086 completely blocked increased neutrophil-endothelial adhesion induced by preeclamptic placental-conditioned medium (13.24 +/- 0.81% versus 31.31 +/- 4.75%, P < .01). CONCLUSION: In preeclampsia, the placenta releases one or more factors promoting neutrophil-endothelial adhesion. The increased neutrophil-endothelial adhesion thereby induced is a PAF-mediated event. It is suggested that if preeclamptic placentas release toxic factors into the maternal circulation in vivo, these factors may contribute to the altered vascular endothelial cell function in preeclampsia.

Azepines↗
PubMedDate not supplied

The Harlaxton experience: transcultural nursing education in the United Kingdom.

Studying nursing in the English countryside provides valuable insight for students taking community health nursing at the University of Evansville's Harlaxton College campus in Grantham, England. Students gain understanding of new, creative methods of nursing while learning to appreciate the value of time-honored approaches to health care delivery. This program can serve as a model particularly for those wishing to study transcultural nursing and alternative ways of delivering nursing and health care.

Community Health Nursing↗