Factors associated with COVID-19 vaccine uptake in a US/Mexico border community: demographics, previous influenza vaccination, and trusted sources of health information.

Background: COVID-19 vaccine uptake has been uneven, particularly across racial/ethnic and age groups. This study seeks to understand factors associated with COVID-19 vaccine uptake in a large cross-sectional sample of predominantly Latinos/Latinas individuals living near the US/Mexico border. Methods: Data are extracted from a 176-item survey conducted as part of a parent study focused on the co-creation of a COVID-19 testing program for underserved communities developed through a partnership between an academic institution and a Federally Qualified Health Center. The following participant variables were examined: health history, COVID-19 symptoms, COVID-19 testing and vaccine experiences, and perceptions of sources of health information. Participant characteristics were compared using chi-square tests. Multivariate logistic regressions were used for the final statistical model. Results: From 1 May 2021 to 30 April 2022, 4,964 adults, 66% of whom were identified as women, completed the survey. Approximately 80% of participants reported having received at least one COVID-19 vaccine. Female sex, older age, Hispanic/Latino(a) ethnicity, previous influenza vaccination, advanced education, and perceived elevated risk of COVID-19 were significantly (p < 0.05) associated with having received a COVID-19 vaccine. Regarding sources of health information, individuals who indicated they trust their doctor, healthcare provider, or the US government "a great deal" were more likely to have received a COVID-19 vaccine compared to individuals who indicated that they trusted these sources "not at all." In contrast, those who reported having "a great deal" of trust in their faith leader or their social media contacts were significantly less likely to have received a COVID-19 vaccine than those who reported that they trusted these sources "not at all." Conclusion: Sex, education, past influenza vaccination, perceived risk of COVID-19 infection, and trust in specific sources of information were correlated with the uptake of COVID-19 vaccination. Additional research is needed to better understand why this confluence of factors, particularly the unique findings about trusted sources of information, are associated with vaccine uptake. Understanding these associations, specifically within underserved, Latino/Hispanic communities, is an important first step to inform efforts aimed at increasing and sustaining COVID-19 vaccine uptake and adoption of other public health interventions.

Upregulated expression of human membrane type-5 matrix metalloproteinase in kidneys from diabetic patients.

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade the extracellular matrix (ECM). The membrane-type matrix metalloproteinases (MT-MMPs) are a new family of MMPs that differ from other MMPs in that they have a transmembrane domain that anchors them to the cell surface. MT-MMPs have been shown to function as receptors and activators for other MMPs and to localize extracellular matrix proteolysis at the pericellular region. Here we report on mRNA and protein expression of the fifth human MT-MMP (MT5-MMP), a 64-kDa protein that is capable of converting pro-MMP-2 to its active form, in human kidney as well as its upregulation in diabetes. We also demonstrate upregulation of the active form of MMP-2 in kidney samples from patients with diabetes. Through immunohistochemistry, MT5-MMP expression was localized to the epithelial cells of the proximal and distal tubules, the collecting duct, and the loop of Henle. Furthermore, the tubular epithelial cells that expressed MT5-MMP were associated with tubular atrophy. Because renal tubular atrophy is a significant factor in the pathogenesis of diabetic nephropathy and renal failure and the molecular mechanisms regulating this process remain unknown, it is hypothesized that the elevated expression of MT5-MMP contributes to the activation of pro-MMP-2, which participates in the remodeling of the proximal and distal tubules as well as in the collecting duct. These results provide the first evidence of the expression of a MT-MMP in diabetes and suggest a novel role for MT5-MMP in the pathogenesis of renal tubular atrophy and end-stage renal disease.

Factor XIIIa cross-links lipoprotein(a) with fibrinogen and is present in human atherosclerotic lesions.

During the development of atherosclerotic lesions, lipoprotein(a) [Lp(a)], a highly atherogenic lipoprotein, accumulates within fibrin clots attached to blood vessel walls. As Lp(a) accumulates within the fibrin clot with time, fatty streaks are formed that develop into occlusive atherosclerotic plaques. It is not understood, however, which mechanisms are involved in the binding of Lp(a) to fibrin and, hence, the stable incorporation of Lp(a) into the fibrin clot. The results of the present study demonstrate that factor XIIIa, a transglutaminase that catalyzes the formation of amide bonds between endo-gamma-glutaminyl and endo-epsilon-lysyl residues of proteins, is capable of cross-linking Lp(a) to fibrinogen, the soluble precursor of fibrin. Biochemical assays were conducted to demonstrate that factor XIIIa cross-links Lp(a) with fibrinogen in a time- and concentration-dependent manner. Additionally, immunohistochemical studies revealed that factor XIII protein expression colocalizes with Lp(a) expression in human atherosclerotic plaques. It is proposed that factor XIIIa-mediated cross-linking of Lp(a) to fibrin effectively increases the local concentration of Lp(a) within a fibrin clot. The accumulation of Lp(a) within the blood vessel promotes an antifibrinolytic environment, foam cell formation, the generation of a fatty streak, and an increase in smooth muscle cell content, all of which may contribute to the pathogenesis of atherosclerosis.

Matrix metalloproteinase expression increases after cerebral focal ischemia in rats: inhibition of matrix metalloproteinase-9 reduces infarct size.

BACKGROUND AND PURPOSE: Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade the extracellular matrix and are implicated in numerous pathological conditions including atherosclerosis, inflammation, and tumor growth and metastasis. In the brain, the endothelial cell wall, strengthened by tight junctions, defines the blood-brain barrier (BBB). The extracellular matrix molecules constitute the basement membrane underlying the vasculature and play a critical role in maintaining the integrity of the BBB. After focal stroke, there is a breakdown of the BBB with an associated increase in vascular permeability, inflammatory cell influx, and neuronal cell death. The present study was designed to investigate the effects of MMP expression after stroke. METHODS: Focal stroke was produced by permanent middle cerebral artery occlusion (MCAO) in the rat, and MMP protein expression was measured by Western blot and zymogram analysis over a time course ranging from 6 hours to 30 days (n=32). Immunohistochemistry at 1 and 5 days (n=8 and 6, respectively) was also utilized to characterize the expression of several MMPs and related proteins after stroke, including their cellular source. To test the hypothesis that early increased MMP-9 expression is involved in ischemic brain injury, a neutralizing monoclonal antibody directed against MMP-9 was administered intravenously (n=7 per group) 1 hour before MCAO, and infarct size was measured 24 hours later. RESULTS: MMP expression increased progressively over time after stroke. After 12 hours, significant (P<0.05) MMP-9 activity was observed that reached maximum levels by 24 hours (P<0.001), then persisted for 5 days at this level and returned to basal (zero) levels by 15 days. On the basis of morphological criteria, MMP-9 appeared to stain with endothelial cells and neutrophils identified both within and at the periphery of the infarct within 24 hours of focal ischemia. After 5 days, MMP-9 appeared to stain with macrophages present within the infarcted brain. MMP-2 activity was significantly (P<0.001) increased by 24 hours and was maximum after 5 days following MCAO. MMP-2 appeared to stain with macrophages present within the infarcted region. Unlike MMP-9 and MMP-2, tissue inhibitor of metalloproteinase-1 was identified at comparable levels in both control and ischemic tissue after MCAO. MMP-1 and MMP-3 could not be detected in the brain after focal stroke. When an MMP-9-neutralizing monoclonal antibody was administered systemically, animals exhibited significantly reduced infarct size (ie, a 30% reduction compared with non-immune antibody controls; P<0.05). CONCLUSIONS: These results demonstrate that early increased MMP-9 expression in endothelial cells and infiltrating neutrophils is a significant response to cerebral focal ischemia and that selective inhibition of MMP-9 activity can significantly reduce brain injury after stroke.

Carvedilol inhibits endothelin-1 biosynthesis in cultured human coronary artery endothelial cells.

Carvedilol, a multiple action neurohumoral antagonist, has been reported recently to significantly reduce mortality in congestive heart failure (CHF) patients. In addition to being a beta-adrenoceptor antagonist, one of the unique aspects of the biological effects of carvedilol is that it is also a potent antioxidant with antimitogenic properties. As there is a significant correlation between plasma immunoreactive endothelin-1 (ET-1) levels and the severity of CHF, the present study was designed to determine the effects of carvedilol on ET-1 biosynthesis in cultured human coronary artery endothelial cells (HCAECs). HCAECs were treated with carvedilol 15 min prior to the addition of serum and ET-1 levels were measured in the cell culture conditioned medium 24 h later. Carvedilol (10 microM) significantly inhibited basal ET-1 production in HCAECs by 62 +/- 8%. Carvedilol produced a concentration-dependent inhibition of serum-mediated stimulation of ET-1 biosynthesis with an IC50 = 1.2 microM. PreproET-1 mRNA expression was also inhibited by carvedilol. Other beta-adrenoceptor antagonists, such as propranolol (10 microM) or celiprolol (10 microM), did not effect ET-1 biosynthesis. Furthermore, the antioxidant probucol (10 microM) did not effect ET-1 production. Immunohistochemical analysis of HCAECs demonstrated that resting HCAECs have expression of ET-1 and can be inhibited by carvedilol. The results of the present study demonstrate that serum stimulation of HCAECs produced an increase in ET-1 expression, and carvedilol treatment caused a marked decrease in stimulated ET-1 expression as compared to serum-treated HCAECs. These data indicate that carvedilol directly inhibits the biosynthesis of ET-1 in HCAECs, and this effect may contribute to its vasodilating and antiproliferative actions. Furthermore, these effects may contribute to the ability of carvedilol to improve clinical outcome in CHF patients.

Carvedilol, a multiple-action neurohumoral antagonist, inhibits mitogen-activated protein kinase and cell cycle progression in vascular smooth muscle cells.

Recent findings that the multiple-action neurohumoral antagonist carvedilol inhibits the mitogenic effects of a broad variety of mitogens and produces marked protection against neointima formation after balloon angioplasty injury prompted further study into the molecular and biochemical mechanism of action. In the present study, the effects of carvedilol on mitogen-activated protein (MAP) kinase activity and cell cycle progression were evaluated. Carvedilol produced significant concentration-dependent inhibition of mitogen-induced MAP kinase activity in rat smooth muscle cells. Furthermore, when MAP kinase was purified from mitogen-stimulated cells by FPLC Mono Q chromatography, carvedilol produced direct enzyme inhibition. In the cell-free assay, carvedilol (10 microM) produced 50% inhibition of MAP kinase activity. Cell flow cytometry studies revealed that quiescent rat aortic smooth muscle cells showed 96% of the cell population in the G0/G1 phase of the cell cycle. The addition of serum (10%) increased the number of cells in S and G2/M phases 20% to 40%, respectively. Carvedilol (10 microM) significantly decreased (30-50%) the number of cells in S and G2/M phase. In addition, carvedilol significantly inhibited (>70%) serum-induced stimulation of the S phase-specific marker thymidine kinase. These data suggest that the antimitogenic actions of carvedilol on vascular smooth muscle may be in part due to the inhibition of MAP kinase activity and regulation of cell cycle progression.

Angiotensin type 1 receptors mediate smooth muscle proliferation and endothelin biosynthesis in rat vascular smooth muscle.

Angiotensin II (AII) has the potential to promote vascular smooth muscle (VSM) hypertrophy and hyperplasia; however, the mechanisms involved in AII stimulation of VSM growth are not fully understood. The AII receptor subtypes in VSM responsible for several biological events leading to cell proliferation have been evaluated. All-induced mitogenesis in explants of rat VSM cells was antagonized by the angiotensin type 1 (AT1)-selective receptor antagonists SK&F 108566 (IC50 = 5.3 +/- 0.96 nM) and DuP 753 (IC50 = 3.5 +/- 0.97 nM), but not by AT2 receptor antagonists. AII-stimulated endothelin (ET)-1 gene expression was antagonized by SK&F 108566 (50% at 1 microM), but not by selective AT2 receptor antagonists. Similarly, AII stimulated the release of immunoreactive ET (irET) from cultured VSM cells that was antagonized by 1 microM SK&F 108566 (72%) and DuP 753 (66%), but not by AT2 receptor antagonists. AII and growth factors that stimulated the release of irET down-regulated the number of ET receptor binding sites. AII (1-100 nM) markedly (6- to 10-fold) stimulated mitogen-activated protein kinase, an enzyme believed to be involved in the pathway for cell proliferation, and this stimulation was blocked (50-75%) by SK&F 108566 (1 nM-1 microM). Phosphoramidon (50 microM) inhibited (60%) both AII-induced irET release and cell proliferation. These data demonstrate that AII-mediated VSM growth is via AT1 receptors, and suggest that AII-induced ET production may contribute to the proliferative response in these cells.

Evidence for involvement of protein kinase C in expression of intracellular adhesion molecule-1 (ICAM-1) by human vascular endothelial cells.

Potent activators of protein kinase C (PKC), such as phorbol dibutyrate and octylindolactam V, stimulated expression of intercellular adhesion molecule 1 (ICAM-1) by human umbilical vein endothelial cells (HUVEC) in a concentration-dependent manner. Expression of PKC activator-induced ICAM-1 in HUVEC was inhibited by the PKC inhibitor, H-7. Furthermore, cytokine (TNF alpha, LPS)-induced ICAM-1 expression was inhibited by the potent PKC inhibitor, H-7, and not by the cAMP-dependent protein kinase (PKA) specific inhibitor, H-89. These data suggest that PKC is involved in cytokine- and inflammatory agent-induced upregulation of ICAM-1 expression in HUVEC.

Carvedilol, a novel cardiovascular agent, inhibits development of vascular and ventricular hypertrophy in spontaneously hypertensive rats.

The effects of carvedilol, a novel cardiovascular agent, were evaluated in developing spontaneously hypertensive rats (SHR) for effects on hemodynamics, and the ability to effect the development of left ventricular, and vascular hypertrophy associated with chronic hypertension. Chronic oral administration of low dose carvedilol (20 mg/kg/day) was initiated when rats were 5 weeks of age, and experiments progressed until 14 weeks of age. Carvedilol-treated SHR had significantly reduced systolic blood pressures and heart rates throughout the duration of the experiment, and had significantly reduced ventricle/body weights by approximately 9.0%. Morphologic analysis of tertiary branches of the mesenteric artery revealed that carvedilol-treated SHR had significant reductions in medial cross-sectional area. Carvedilol produced concentration-dependent inhibition of basal [3H]thymidine incorporation in cultured SHR vascular smooth muscle cells, as well as by stimulation produced by PDGF (1 nM), EDGF (1 nM), thrombin (0.5 U/ml), or endothelin-1 (1 nM), indicating that carvedilol had direct anti-mitogenic activity. The present studies demonstrate that low dose carvedilol produced sustained reductions in blood pressure and heart rate in developing SHR that were accompanied by significant inhibition in the development of vascular and myocardial hypertrophy. The morphological changes induced by carvedilol may be mediated by a combination of hemodynamic effects, as well as by direct anti-mitogenic effects on vascular smooth muscle.

Carvedilol, a cardiovascular drug, prevents vascular smooth muscle cell proliferation, migration, and neointimal formation following vascular injury.

Carvedilol is a cardiovascular drug currently used for the treatment of hypertension. Clinical studies have recently demonstrated efficacy in angina and congestive heart failure. Recently, carvedilol has been shown to attenuate oxygen free radical-initiated lipid peroxidation and to inhibit vascular smooth muscle mitogenesis induced by a wide variety of growth factors. These findings are of interest since smooth muscle proliferation and abnormal lipid metabolism are proposed to play an important role in the pathogenesis of atherosclerotic plaque formation and in development of stenotic lesions following vascular injury by balloon angioplasty and coronary artery bypass grafting. On the basis of these observations, the antiproliferative actions of carvedilol have been explored in detail. In human cultured pulmonary artery vascular smooth muscle cells, carvedilol (0.1-10 microM) produced a concentration-dependent inhibition of the mitogenesis stimulated by platelet-derived growth factor, epidermal growth factor, thrombin, and serum, with IC50 values ranging from 0.3 to 2.0 microM. Carvedilol also produced a concentration-dependent inhibition of vascular smooth muscle cell migration induced by platelet-derived growth factor, with an IC50 value of 3 microM. The extensive neointimal formation that occurs following balloon angioplasty of rat carotid arteries was markedly attenuated by carvedilol (1 mg/kg, i.p.; twice daily starting 3 days before angioplasty and continuing until 14 days after angioplasty). Quantitative image analysis demonstrated that carvedilol reduced the neointimal growth following angioplasty by 84% without altering either medial or adventitial cross-sectional areas. These observations indicate that carvedilol may also be effective in the treatment of pathological disorders principally associated with abnormal vascular smooth muscle growth, such as atherosclerosis and acute vascular wall injury induced by angioplasty or coronary artery bypass grafting.

Fluid resuscitation improves survival of endotoxemic or septicemic rats: possible contribution of tumor necrosis factor.

The present study was designed to investigate the effects of fluid administration on survival in endotoxemic or septicemic male Sprague-Dawley rats. Endotoxemia was induced by intravenous injection of Escherichia coli lipopolysaccharide (LPS), and septicemia produced by cecal ligation and puncture (CLP). In endotoxemic animals deprived of fluid resuscitation, 7-day survival following injection of LPS at doses of 1, 3, or 10 mg/kg LPS were 70% (n = 10), 30% (n = 10), and 0% (n = 10), respectively. In rats resuscitated with 3.3 ml/kg/h of 0.9% NaCl, the dose-response curve for survival was shifted 5-fold rightward in a parallel manner (p < 0.001, between the fluid-resuscitated and nonfluid resuscitated LPS groups), indicating a reduced sensitivity to the effects of LPS following fluid resuscitation. LPS increased serum tumor necrosis factor (TNF alpha) concentrations in fluid-resuscitated endotoxemic animals from a baseline value of 20 U/ml to 2,350 U/ml at 1 h, which returned to 200 U/ml at 2 h. In endotoxemic animals not receiving fluid resuscitation, serum TNF alpha levels at 1 and 2 h were 5-fold and 27-fold higher, respectively, than in fluid-resuscitated animals. There were no differences in arterial blood pressure or heart rate between the two groups of endotoxemic animals; total peripheral resistance was significantly lower at 1 h, and cardiac index was significantly greater at 3 h in the fluid-resuscitated LPS group; otherwise there were no further differences in hemodynamic parameters between the two groups. The survival rate at 4 days following CLP without fluid resuscitation was 14%, whereas CLP with fluid resuscitation improved survival to 74% (p < 0.01). TNF alpha was undetectable (i.e., < 20 U/ml) in the serum of animals subjected to CLP. The improvement in survival with fluid infusion in the LPS and CLP models cannot be attributed to catheter implantation, or to improved hemodynamic parameters in the LPS model. The improvement in survival in the LPS model with fluid infusion was associated with attenuated increases in TNF alpha levels. Furthermore, these studies illustrate that fluid-resuscitated and nonfluid-resuscitated experimental animal models should not be considered equivalent.

Carvedilol inhibits vascular smooth muscle cell proliferation.

The antiproliferative properties of carvedilol, a newly developed multiple-action antihypertensive agent, were evaluated in early passage cultured rat aortic vascular smooth muscle cells. Carvedilol (10(-7)-10(-5) M) produced concentration-dependent decreases in basal and endothelin-1-stimulated mitogenesis of rat aortic vascular smooth muscle cells. The IC50 for inhibition of [3H]thymidine incorporation by carvedilol in both basal and endothelin-1-stimulated rat aortic vascular smooth muscle cells was approximately 1 microM. Carvedilol (10 microM) inhibited basal mitogenesis by approximately 65%, and endothelin-1-stimulated mitogenesis by approximately 95%. Carvedilol (1-10 microM) also produced significant concentration-dependent inhibition of the mitogenic response mediated by thrombin (0.5 U/ml), epidermal growth factor (1 nM), platelet-derived growth factor (1 nM), and angiotensin II (5 nM). Endothelin-1- or PDGF A/B-induced increases in cell number were also significantly inhibited by carvedilol (10 microM). The antimitogenic effect of carvedilol on cell growth was reversible. The inhibitory effect of carvedilol was not shared by other beta-adrenoceptor antagonists such as labetalol (10 microM), celiprolol (10 microM), or sotalol (10 microM), which did not significantly affect [3H]thymidine incorporation in rat vascular smooth muscle cells. Propranolol (10 microM) was the only beta-adrenoceptor antagonist tested that inhibited [3H]thymidine incorporation, with effects of approximately 50 and 75% on basal and endothelin-1-mediated stimulation, respectively. In contrast, celiprolol (10 microM) produced significant stimulation of DNA synthesis (125% over basal). The calcium channel antagonist nifedipine (10 microM) inhibited basal and endothelin-1-mediated mitogenesis by 58 and 72%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

CGRP stimulates the adhesion of leukocytes to vascular endothelial cells.

Calcitonin gene-related peptide (CGRP) stimulates the adhesiveness of human umbilical vein endothelial cells for U937 cells and human neutrophils in a dose- and time-dependent manner. The onset of CGRP-induced adhesives of HUVEC was rapid (30 min), independent of protein synthesis, and lasted over 24 h in the continuous presence of the peptide. The stimulatory effect of CGRP was completely blocked by the CGRP antagonist, CGRP(8-37). The present study provides evidence in support of the potential role of sensory nerve-derived neuropeptides in the modulation of leukocyte adhesion to vascular endothelial cells.

The selective endothelin ETA receptor antagonist BQ123 antagonizes endothelin-1-mediated mitogenesis.

The mitogenic effects of endothelin isopeptides and the selective ETA receptor antagonist BQ123 were evaluated in rat aortic vascular smooth muscle cells. Endothelin-1 (ET-1) and endothelin-3 (ET-3) produced concentration-dependent increases in [3H]thymidine incorporation (EC50 = 0.1 and 25 nM, respectively). The ETB-selective agonist sarafotoxin 6c did not produce significant effects on [3H]thymidine incorporation. BQ123 produced selective and concentration-dependent inhibition of ET-1-mediated [3H]thymidine incorporation. These data demonstrate that ET-1-mediated mitogenesis in vascular smooth muscle is mediated by ETA receptors.

Evidence for the involvement of carbohydrate moieties in the adhesion of U937 cells to tumor necrosis factor-alpha (TNFalpha)-stimulated vascular endothelium in vitro.

Treatment of U937 cells with fructose 1-phosphate (P) and fucoidan dose-dependently inhibited the adhesion of these monocytic cells to TNF alpha-stimulated human umbilical vein endothelial cells (HUVEC) (IC50 = 1 mM and 10 micrograms/ml respectively). These carbohydrates (CHO) failed to inhibit U937 adhesion to unstimulated (basal) HUVEC or phorbol 12, 13 dibutyrate (PdBu)-stimulated HUVEC. At 10 mM concentration, both fucose 1-P and lactose 1-P inhibited TNF alpha-stimulated adhesion while the latter also inhibited basal adhesion. Fructose 6-P, fucose, galactose 1-P, glucose 1-P, glucose 6-P, glucuronic acid, beta-glycerol 1-P, mannose 1-P, mannose 6-P, ribose 1-P and ribose 5-P tested at 10 mM did not inhibit U937 cells adhesion to basal or TNF alpha-stimulated HUVEC. These data suggest that CHO may play an important role in modulating monocytes adhesion to cytokine-induced adhesion molecule(s) on the surface of HUVEC.

Neuropeptide Y upregulates the adhesiveness of human endothelial cells for leukocytes.

The nervous system and the autonomic system in particular have been associated with stress-induced changes in host resistance to infections and inflammatory reactions. Since a key step in initiation of inflammation is adhesion of leukocytes to the endothelium, we hypothesized that neuron-derived factors might be involved in this process. Neuropeptide Y (NPY), a 36-amino acid neuropeptide that is colocalized and released with norepinephrine from sympathetic nerves, has already been implicated in inflammatory reactions via modulation of histamine release from mast cells. This study was undertaken to examine the potential role of NPY in proinflammatory processes via modulation of endothelium-leukocyte interaction. NPY (0.01-10 microM) increased the adhesion of 51Cr-labeled human neutrophils or the human monocytic U937 cell line to human umbilical vein endothelial cells in a dose- and time-dependent manner. The stimulation of human umbilical vein endothelial cell adhesiveness occurred as early as 30 minutes and lasted over 48 hours. The increase of leukocyte adhesion to human umbilical vein endothelial cells by NPY was not inhibited by protein synthesis inhibitor cycloheximide, nor was it associated with expression of intercellular adhesion molecule-1 on human umbilical vein endothelial cells; in contrast, strong expression of intercellular adhesion molecule-1 was induced by tumor necrosis factor alpha and lipopolysaccharide endotoxin. These data suggest that neuron-derived factors such as NPY may serve as modulators of not only the neuromuscular unit but also the interaction of endothelial cells with leukocytes. In this capacity, the sympathetic nervous system might play an important role in the regulation of proaggregatory and hemostatic activity of microvessels.

Modulation of U937 cell adhesion to vascular endothelial cells by cyclic AMP.

Adhesion of leukocytes to the endothelium is an essential event in inflammatory cell emigration from intravascular to extravascular compartment. While many mediators (e.g. cytokines) enhance cell adhesion through expression of adhesion molecules on endothelial cells the mechanism of this phenomenon is not known. In this study we examined the role of cAMP in mediation of the adhesion of monocytic cell line, U937 to human umbilical vein endothelial cells (HUVEC). Incubation of HUVEC with cholera toxin (10-500 ng/ml) for 4 hrs greatly enhanced the adhesiveness of HUVEC for U937 cells. The magnitude of adhesion stimulation produced by cholera toxin was comparable to that produced by the cytokines TNF alpha or IL-1 (2-3 folds). Upregulation of U937 cells adhesion to HUVEC was also achieved by short incubation (less than 1 hr) of HUVEC with cAMP elevating agents such as forskolin (10 microM), isoproterenol (0.3-30 microM), epinephrine (10-100 microM), norepinephrine (100 microM) as well as by endogenously added dibutyryl cAMP (0.05-2.0 mM). Dibutyryl cyclic GMP (0.05-2.0 mM) was ineffective in promoting adhesion. These data suggest that cAMP might be an important intracellular modulator of leukocyte adhesion to endothelium and therefore promoter of pro-inflammatory processes.

Biosynthesis and modulation of endothelin from bovine pulmonary arterial endothelial cells.

The biosynthesis and modulation of the vasoconstrictor peptide endothelin was studied in the conditioned medium from cultured bovine pulmonary artery endothelial (BPAE) cells. Conditioned medium from cultured BPAE cells produced contraction of isolated rabbit aortic rings. Incubation of BPAE cells with the protease inhibitors TPCK or isatoic anhydride attenuated the extent of conditioned medium-induced contractions. Incubation of BPAE cells with thrombin produced an enhancement of conditioned medium-induced contraction by approximately 25%. Endothelin levels in conditioned medium were measured by RIA and incubation of BPAE cells with TPCK or isatoic anhydride significantly reduced endothelin levels, whereas incubation with thrombin or transforming growth factor beta-1 stimulated the levels of endothelin in the conditioned medium. These data indicate that endothelin may be modulated by certain protease inhibitors and by platelet and immune cell mediators and suggest a potential new mode of vascular tone regulation.

Endothelial thromboxane receptors: biochemical characterization and functional implications.

We have identified thromboxane specific receptors in membrane preparations of bovine pulmonary artery endothelial cells using a potent thromboxane specific antagonist, [125I]-PTA-OH in a binding assay. The binding was specific and saturable. Neither thromboxane B2, prostaglandin D2 nor prostaglandin F2 alpha displaced the ligand (0.1 nM) at concentrations up to 10 microM. However, binding was displaced by IPTA-OH greater than SQ29548 greater than U46619. In addition, we observed that thromboxane mimetic U46619 significantly lowered the basal production of prostacyclin and also markedly suppressed bradykinin-stimulated prostacyclin released by endothelial cells. We propose that an important biological effect of thromboxane on vascular endothelial cells may be the suppression of prostacyclin production.