Cytotoxicity-associated effects of reactive oxygen species on endothelin-1 secretion by pulmonary endothelial cells

In this study bovine pulmonary artery endothelial cells (BPAEC) were used as a model system to investigate the effects of the hypoxanthine-xanthine oxidase (HXXO) oxygen radical donor system on ET-1 secretion into pulmonary vasculature. Incubation of BPAEC with HXXO for 4 h caused a significant reduction in ET-1 secretion, which was significantly offset by allopurinol or catalase, but not by Cu/Zn superoxide dismutase (SOD). ET-1 secretion was also reduced by H2O2, and this effect was again significantly offset by catalase. XO alone also reduced ET-1 secretion, but to a significantly lesser degree than did HXXO, and this effect was not offset by allopurinol, catalase, or SOD. None of the oxidant treatments were associated with a loss of immunoreactive ET-1 from endothelial cell medium containing synthetic peptide. The HXXO- and H2O2-mediated reductions in ET-1 secretion were accompanied by evidence of reduced cell viability. This loss of viability was absent when cells were treated with HXXO + catalase, allopurinol, or mercaptopropionyl glycine, but not when SOD was present. We conclude that under conditions of oxidative stress, the pulmonary vascular endothelium responds by secreting less ET-1. This may be relevant to its vasodilator functions in the pulmonary vasculature, which would therefore be compromised when the endothelium is exposed to oxidant stress.     

Elevated plasma endothelin-1 level in streptozotocin-induced diabetic rats and responsiveness of the mesenteric arterial bed to endothelin-1

Acute swimming stress destroyed the circadian rhythm of motility in rats. Bilateral electrolytic lesion of the dorsal hippocampus increased the night activity and resistance of animals to stress. Pinealectomy did not affect the circadian locomotion but increased rats' sensitivity to dysrhythmic stress effect.     

Inhibition of plasma endothelin-1 concentration by captopril in patients with essential hypertension

The aim of this study was to determine whether captopril has any effect on plasma endothelin-1 (ET-1) concentration in patients with essential hypertension. Nine normotensives and eleven hypertensives were included in this study. Blood pressure and pulse rate were monitored before and at 60 min after captopril ingestion (25 mg). Simultaneously, blood samples for plasma ET-1 and plasma renin activity (PRA) determination were obtained. In the normotensives, captopril treatment resulted in a significant rise in PRA, but without statistical changes in blood pressure and plasma ET-1. By contrast, in the hypertensives, although PRA elevated similarly after captopril, both blood pressure and plasma ET-1 decreased significantly compared with their respective preloading level. These data suggest that the blood pressure-lowering effect of captopril in essential hypertension may be at least in part, mediated by its inhibition of ET-1 production from the vascular endothelium.     

Increased concentrations of endothelin-1 messenger RNA in tissues and endothelin-1 peptide in plasma in septic pigs: modulation by betamethasone

OBJECTIVES: To study the expression of preproendothelin-1 messenger RNA (mRNA) in tissue after Escherichia coli lipopolysaccharide challenge and to evaluate the possible effects of betamethasone both regarding endothelin-1 production as well as hemodynamic and vascular effects during E. coli lipopolysaccharide infusion in pigs in vivo. DESIGN: Prospective trial. SETTING: Laboratory at a university medical center. SUBJECTS: Ten domestic pigs, weighing 18 to 25 kg. INTERVENTIONS: Anesthetized pigs were given continuous infusions of E. coli lipopolysaccharide (15 micrograms/kg/hr for 3 hrs), with or without prior treatment with betamethasone (0.5 mg/kg im 12 hrs before the start of the surgical preparation and 0.5/kg iv at the start of the preparation). MEASUREMENTS AND MAIN RESULTS: The E. coli lipopolysaccharide infusion evoked the characteristic cardiovascular changes observed in septic shock: decreased mean arterial pressure and cardiac output; increased heart rate and increased pulmonary vascular resistance. Large increases in both arterial plasma concentrations of endothelin-1-like immunoreactivity, as well as preproendothelin-1 mRNA concentrations in tissues, were also observed during the E. coli lipopolysaccharide infusion. Treatment with betamethasone significantly attenuated the E. coli lipopolysaccharide-induced increase in endothelin-1 plasma concentrations, whereas the increased mRNA concentrations were only slightly affected. Furthermore, betamethasone treatment also affected cardiovascular parameters, with significant attenuation of the E. coli lipopolysaccharide-induced increase in heart rate and a higher cardiac output after 60 mins of the E. coli lipopolysaccharide infusion. The urine production, which was markedly decreased during the E. coli lipopolysaccharide infusion, was significantly higher in the betamethasone-treated group compared with the control group. CONCLUSIONS: The present results indicate that the increased concentrations of endothelin-1-like immunoreactivity that are observed in septic shock may have negative effects on both cardiovascular parameters as well as renal function, which is in agreement with a possible role for endothelin-1 in the pathogenesis of septic shock.     

Minimal daily variations of plasma and urinary endothelin-1 in healthy subjects

The daily profiles of both the plasma level and the urinary excretion rate of endothelin-1 were examined in 13 healthy volunteers (9 males and 4 females, aged 22 +/- 1 [SEM]). Plasma endothelin-1 (PET) was measured after a one-hour recumbency every 6 hours at 8 a.m., 2 p.m., 8 p.m. and 2 a.m. and the urinary excretion rate of endothelin-1 (UET) was determined in the urine collected every 6 hours. PET was found to be quite stable throughout the day, being 1.57 +/- 0.25 pg/ml at 8 a.m., 1.88 +/- 0.21 at 2 p.m., 2.2 +/- 0.24 at 8 p.m. and 1.90 +/- 0.20 at 2 a.m. After a one-hour ambulation, PET showed no statistical difference. UET also remained unchanged for each 6-hour collecting period, measuring 4.61 +/- 0.69, 3.98 +/- 0.46, 4.63 +/- 0.73 and 3.42 +/- 0.49 ng/hr, respectively. The absence of any daily variations in either PET or UET thus suggests that apparently no specific considerations need be applied regarding the time of taking samples to measure the plasma and urinary endothelin-1.     

Color Doppler imaging and plasma levels of endothelin-1 in low-tension glaucoma

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide produced by vascular endothelin cells There are reports in the literature that ET-1 plasma levels are raised in low tension glaucoma (LTG). ET-1 plasma concentration and Color Doppler Imaging (CDI) evaluation in ophthalmic and posterior ciliary arteries were measured in 15 LTG patients and in 15 healthy subjects. The blood flow index recorded for the ophthalmic artery in normal subjects was a PSV of 36.646 +/- 6.611 cm/sec with RI of 0.717 +/- 0.019 while in the LTG patients it was 32.961 +/- 3.045 cm/sec (p < 0.003) with RI of 0.789 +/- 0.018 (p < 0.001). For the posterior ciliary arteries in the same two groups, we obtained a PSV of 13.878 +/- 4.149 cm/sec vs 8.720 +/- 1.645 cm/sec (p < 0.001) and an RI of 0.679 +/- 0.039 vs 0.722 +/- 0.024 (p < 0.001). The plasma ET-1 level in normal subjects was 1.720 +/- 0.174 pg while in LTG patients it was 2.947 +/- 0.217 pg (p < 0.001). On the basis of our experience, we think that GON and the visual field damage found in LTG can be attributed to an alteration in the endothelial self-regulating sections and consequent vascular insufficiency, particularly pronounced in the posterior ciliary arteries which, since it is these that provide the blood supply to the optic nerve head, leads to irreversible functional damage.     

Raised plasma endothelin-1 concentrations in patients with primary hypercholesterolemia without evidence of atherosclerosis

This study investigated the Psychosocial adjustment in 40 patients who received orthotopic liver transplantation (OLT) for several endstage liver diseases. Twenty patients were grafted because they suffered from liver Cancer as well as cirrhosis. Particular attention was paid to evaluating whether cancer could affect recipients' coping with transplant. Each patient underwent a semi-structured interview to obtain information on their psychosocial life, relationship with the donor, organ acceptance and life expectancy. Interview was performed I year after transplantation. A psychodiagnostic evaluation was also performed using a Minnesota Multiphasic Personality Inventory (MMPI) and a Human Figure Test. Psychosocial adaptation in everyday life following liver transplantation seemed good in most of the patients, whatever the indication for transplantation might be. It can he seen that by replacing the diseased organ a high percentage of oncological patients overcame their fear of cancer.     

Ultrastructural study of plasma membrane GM1 in neuroectodermal cells using cholera-peroxidase

Cholera toxin was coupled to peroxidase to yield a highly specific marker for GM1 gangliosides. Study of embryonic brain cells in culture revealed intense binding of cholera-peroxidase by plasma membranes of both neurons and glial cells. In contrast, long-term monolayer glioblastoma cultures, including one producing C-type virus, revealed virtually no labelling of their plasma membranes. Such cells were shown to be capable of incorporating exogenously applied GM1 into their plasma membranes. Studies with fixed brain and synaptosomal fractions were in accord with results on embryonic brain cells in culture, and autoradiographic findings with 125I cholera supported observations made utilizing cholera-peroxidase. From our studies there is some indication that long-term propagation in vitro alters the plasma membrane GM1.     

Increased plasma endothelin-1 concentrations in E. coli septic peritonitis rats with diabetes mellitus

To study the diabetic mellitus (DM) patient's reaction to sepsis, we investigated the survival rate, the bacteremia, plasma endotoxin and plasma endothelin-1 levels in E. coli septic peritonitis rats with or without streptozotocin-induced DM. No significant difference could be detected between the DM and nondiabetic rats in the survival rate, the bacteremia level or the plasma endotoxin level. The DM rat manifested a significant increase compared to the nondiabetic rat in the plasma endothelin-1 level four hours after the outbreak of peritonitis. Endothelin-1 may thus play some role in the E. coli septic peritonitis rat with DM.     

Isometric handgrip exercise increases endothelin-1 plasma levels in patients with chronic congestive heart failure

This study demonstrated an immediate and short-lasting endothelin-1 release in the circulation of patients with severe chronic congestive heart failure during isometric handgrip exercise, but not in normal subjects. Our data suggest that endothelin-1 levels may increase transiently during daily physical activity, thus contributing to progressive deterioration of left ventricular function.     

Modulation by endothelin-1 of tissue plasminogen activator and plasminogen activator inhibitor-1 release from cultured human vascular endothelial cells: interaction of endothelin-1 with cytokines

The interaction of endothelin-1 (ET-1) with either interleukin-1 beta (IL-1 beta) or tumor necrosis factor alpha (TNF alpha) on the release of tissue plasminogen activator antigen (t-PA:Ag) and plasminogen activator inhibitor-1 antigen (PAI-1:Ag) was investigated in a culture system of vascular endothelial cells derived from human umbilical vein. The t-PA:Ag release was significantly decreased by either IL-1 beta or TNF alpha; ET-1 intensified the suppressive effect of the cytokines. In contrast, PAI-1:Ag release was significantly increased by either IL-1 beta or TNF alpha; ET-1 significantly reduced the stimulatory effect of the cytokines. The data suggest that endothelial cell-mediated fibrinolysis may be modulated by ET-1.     

Comparable potent coronary constrictor effects of endothelin-1 and big endothelin-1 in humans

BACKGROUND: Endothelin-1 (ET-1) is a potent vasoconstrictor produced from the precursor big ET-1 in endothelial cells. The coronary effects of these peptides in humans in vivo are unknown. Therefore, the effects of ET-1 and big ET-1 on coronary blood flow in relation to plasma ET-1 and big ET-1 levels were compared in healthy subjects. METHODS AND RESULTS: The peptides were infused intravenously at the rates of 0.2, 1, and 8 pmol/kg per minute. Each dose administered for 20 minutes except the highest dose of ET-1, which was administered for 10 minutes. ET-1 and big ET-1 evoked dose-related increases in mean arterial blood pressure from 93 +/- 4 to 107 +/- 4 mm Hg and from 89 +/- 2 to 122 +/- 5 mm Hg, respectively, at the highest dose. ET-1 and big ET-1 reduced coronary sinus blood flow, measured with thermodilution by a maximum of 25 +/- 4% and 28 +/- 8% and increased coronary vascular resistance by 50 +/- 9% and 107 +/- 26%, respectively. Coronary sinus, but not arterial, oxygen saturation was reduced in parallel with the coronary sinus blood flow. The effects of ET-1 and big ET-1 were similar at corresponding time points. During infusion of ET-1, a 19 +/- 5% extraction of ET-1 was observed over the coronary vascular bed (P < .05). Administration of big ET-1 elevated arterial plasma ET-1 levels by 2.4-fold, and after correction for the local extraction of ET-1, a myocardial production of ET-1 was observed. CONCLUSIONS: ET-1 and big ET-1 induce comparable increases in blood pressure and coronary constriction in humans in vivo. The results also suggest a net local removal of circulating ET-1 and big ET-1 and a local conversion of big ET-1 into ET-1 within the coronary vascular bed.     

The composition of individual molecular species of plasma phosphatidylcholine in human pregnancy

The role of medical informatics in telemedicine is dependent on using the power of the computerized database to not only feed patient specific information to the health care providers, but to use the epidemiological and statistical information in the data base to improve decision making and ultimately care. The computer is also a powerful tool to facilitate standardizing and monitoring of care and when applied in continuous quality improvement methodology it can enhance the improvement process well beyond what can be done by hand. The coupling of medical informatics with telemedicine allows sophisticated medical informatics systems to be applied in low population density and remote areas.     

Detection and quantification of apoptosis in transiently transfected adherent cells

Apoptosis is a highly conserved form of cell death present in all eukaryotic cell types and controlled by multiple genes. Several methods have been developed to quantify apoptosis, but none is adapted for all cell types. It is particularly difficult to reliably assay apoptosis of adherent cells. We describe a new, rapid and reliable flow cytometric method which can be used for quantifiying apoptosis in a sub-population of transiently transfected adherent cells. This technique is based on the detection of transfected cells and the apoptotic sub-population by immunofluorescence and Annexin-V labelling, respectively.     

Immunoreactive endothelin-1, endothelin-2 and big endothelin-1 in follicular fluids of women undergoing ovulation induction for in-vitro fertilization

Atlantic cod (Gadus morhua) transferrin cDNAs were isolated from a liver cDNA library using a cod transferrin-derived polymerase chain reaction product as a hybridization probe. The composite nucleotide sequence of two overlapping clones was 2223 bp in length excluding the poly(A) sequence and was equivalent to 87% of the 3' end of the Atlantic salmon transferrin cDNA sequence. Comparison of the deduced amino acid sequence of cod, salmon, Xenopus and several mammalian transferrins revealed that the two fish sequences are more similar with respect to their amino acid sequence and the position of additions/deletions than to other vertebrate transferrins. Conservation of the iron-binding domains and cysteine residues involved in disulphide bridges indicates that all transferrins share similar tertiary structure and support the hypothesis that extant vertebrate transferrin genes were derived from a gene duplication before the divergence of fish, frogs and mammals. Cod transferrin mRNA was detected in both brain and liver RNA and to a much lesser extent in RNA isolated from kidney and heart in contrast to salmon and several other vertebrates in which the transferrin gene is not expressed in brain.     

Proliferative potentials of glioma cells and vascular components determined with monoclonal antibody MIB-1

We present four cases of esophageal rupture (three iatrogenic, one Boerhaave syndrome) to demonstrate the difficulty in diagnosis and therapy. The current literature is discussed and conclusions are drawn as regards the modus operandi. All our patients were operated on. The site of esophageal rupture was always closed with a primary suture and substantial irrigation and drainage were performed. In two cases the suture line was in addition covered with fibrin glue or by an omentum flap, respectively. All patients survived and recovered was unremarkable. Our own results and a subsequent analysis of literature allow the following conclusions. At an early stage of esophageal rupture surgical intervention is indicated. The method of choice is primary closure of the rupture site by suture, possibly combined with a muscle or omentum flap. In cases of delayed diagnosis with advanced mediastinitis, suture of the rupture site should also be striven for. Additional coverage is advisable in these cases. Resection procedures with or without reconstruction should be done only in exceptional cases before of the high surgical risk.     

Influence of intensive physical training on urinary nitrate elimination and plasma endothelin-1 levels in patients with congestive heart failure

The use of doxorubicin as an anticancer drug is limited by its cardiac toxicity. To examine the adverse effects of doxorubicin on cardiac function and ventricular-vascular coupling in piglets, eight piglets received five doses of intravenous doxorubicin, 1.5 mg/kg/dose, every 4-7 days starting at 3 weeks of age. A control group consisted of eight normal piglets. Using conductance and manometric catheters, indices of cardiac function, including end systolic elastance (Ees), preload-recruitable stroke work, dP/dtmax, tau, dP/dtmin, dV/dtmax, and end systolic stiffness, were calculated from volume and pressure measurements at rest and during infusion of isoproterenol. Ventricular-vascular coupling was examined by measuring arterial elastance (Ea) and Ea/Ees. Significant differences in relaxation were found between groups. Indices of diastolic stiffness and of contractile function were not different between groups. Baseline contractile efficiency was increased in the doxorubicin group. Ea and Ea/Ees were lower in the doxorubicin group. Ea/Ees was near 1 at baseline in the doxorubicin group, indicating that conditions were optimized for performance of external stroke work. Therefore, the reserve to increase external cardiac work was diminished. The finding of altered diastolic function suggests the importance of screening of diastolic indices to detect the earliest disturbances in cardiac function caused by doxorubicin.     

Effects of endothelin-1 on Ca2+ signaling and secretion in parathyroid cells

It has been previously reported that parathyroid cells express endothelin (ET) receptors and secrete ET-1 in an extracellular Ca2+ concentration ([Ca2+]e)-dependent manner. Here, we examined the effects of ET-1 on intracellular signaling and parathyroid hormone (PTH) secretion in dispersed bovine parathyroid (bPT) cells, which comprise several cell types including epithelial and endothelial cells, in two cell lines, the rat parathyroid epithelial (PT-r) and the bovine parathyroid endothelial (BPE-1) cells. An RNA-polymerase chain reaction analysis revealed that both ETA and ETB receptors are expressed in bovine parathyroid tissue and BPE-1 cells, and only the ETA receptor is expressed in PT-r cells. PT-r cells also expressed an inositol 1,4,5-trisphosphate (Ins[1,4,5]P3) receptor, and ionomycin induced an increase in the intracellular Ca2+ concentrations ([Ca2+]i) in a Ca(2+)-deficient medium, indicating the presence of an operative intracellular Ca2+ pool in these cells. In cells bathed in 1 mM [Ca2+]e, ET-1 induced a rapid and transient increase in the Ins(1,4,5)P3 production, which was associated with a similar profile of increase in [Ca2+]i and with a peak response of about 800 nM. No changes in the profile of [Ca2+]i responses were observed in ET-1-stimulated cells in the presence of Ca2+ channel blockers, or in Ca(2+)-deficient medium, indicating that Ca2+ mobilization was not associated with Ca2+ entry. Furthermore, a sustained stimulation with ET-1 induced a decrease in [Ca2+]i below the prestimulatory level in a large population of cells, and the percentage of the cell population that shows the sustained decrease of [Ca2+]i increased in higher ET-1 concentrations. [Ca2+]i in PT-r cells was also controlled by a [Ca2+]e-dependent mechanism that changed [Ca2+]i from 28 to 506 nM in a 0.1-3 mM concentration range with an EC50 of 1.2 mM, which is comparable to that reported for bPT cells. In the same range of [Ca2+]e, PTH secretion from bPT cells was inhibited with an IC50 of 1 mM, and ET-1 increased PTH release in a dose-dependent manner but without affecting the IC50 for the [Ca2+]e-dependent inhibition. Thus, the parathyroid epithelial cells appear to respond to ET-1 in a unique way, and the ET autocrine system can be regarded as a possible mechanism to modulate the sensitivity of [Ca2+]e-dependent PTH release.     

Changes in plasma endothelin-1 and lipid peroxidate levels and amount of superoxidate dismutase in red blood cell in patients with pregnancy-induced hypertension

OBJECTIVE: To evaluate the role of endothelin (ET-1) and lipid peroxide (LPO) in the pathogenesis of pregnancy-induced hypertension (PIH). METHODS: The plasma concentrations of ET-1, LPO and the amount of superoxide dismutase (SOD) in red blood cell were measured by radioimmunoassay, thiobarbituric acid fluorimetric determination and catechol self-oxidation determination respectively in total 95 women (normal non-pregnant women 15, Late pregnant women 20 and patients with PIH 60). RESULTS: (1) The levels of ET-1, LPO and SOD in normal late pregnant women were significantly higher than those in non-pregnant women (P < 0.01), but the LPO/SOD ratio was not significantly different between the two groups. (2) The levels of plasma ET-1 and LPO/SOD ratio in cases with PIH were markedly higher than those in normal late pregnant women, and it increased with the severity of the disease and returned to the levels of normal late pregnant women within 3-7 days after delivery. (3) There was a positive correlation between ET-1 and LPO/SOD ratio in PIH. CONCLUSIONS: The imbalance of oxidation and antioxidation and endothelial cell injury may play an important role in the pathogenesis of PIH.