Effects of parathyroid hormone-related peptide on the large conductance calcium-activated potassium channel and calcium homeostasis in vascular smooth muscle cells

AIM

To demonstrate the impact of the parathyroid hormone-related peptide (PTHrP) on the large conductance calcium-activated potassium (BKCa) channels in vascular smooth muscle cells (VSMC) and hyperpolarization of the cell membrane and its dependence on calcium.

MATERIALS AND METHODS

VSMC were isolated from rat aorta and further subcultured. Four experiments were conducted in calcium-release measurements and each of them consisted of a control group, PTHrP, chemical substance, and PTHrP + chemical substance. Chemical substances used were: iberiotoxin, xestospongin C, xestospongin D, and thapsigargin, respectively. Fura-2 imaging was used to determine changes in calcium release of VSMC. In membrane-potential experiments, groups were designed similarly to the Fura-2 imaging experiments: iberiotoxin, BAPTA, and xestospongin D were added, in respective order. Changes in the membrane potential were examined using the fluorescence dye (DiBAC).

RESULTS

Given in a dose between 0.01 and 1.0 μmol/L, PTHrP caused a concentration-dependent decrease in fluorescence intensity, with a maximum effect at 0.5 μmol/L. The decrease, therefore, demonstrated a PTHrP-induced hyperpolarization of the VSMC. The effect was blocked by use of iberiotoxin (100 nmol/L), a highly selective inhibitor of BKCa. Furthermore, when the calcium chelator BAPTA (10 μmol/L) was added, there was a significant reduction in PTHrP-induced hyperpolarization. Use of PTHrP (0.5 μmol/L) also decreased the fluorescence intensity of the indicator for intracellular calcium, Fura-2AM (a membrane-permeable derivative of Fura 2). This effect was re-blocked by use of iberiotoxin. Xestospongin C (3 μmol/L) and xestospongin D (6 μmol/L), both inhibitors of the inositol 1,4,5 trisphosphate-triggered calcium release, inhibited the effects of PTHrP. Additionally, thapsigargin (1 μmol/L), a sarcoplasmic/endoplasmic reticulum Ca2+-ATPase inhibitor, inhibited the effect of PTHrP.

CONCLUSION

The results of our study show that PTHrP induces hyperpolarization and activates BKCa in VSMC. The activation of BKCa channels is calcium dependent; activation is linked to the inositol 1,4,5 trisphosphate-triggered calcium release and is also dependent on the endo/sarcoplasmic reticulum calcium pump.

The impact of statins on FGF-2-stimulated human umbilical vein endothelial cells

AIM

To determine the effects of different types of statins on proliferative and migrative behaviors of basic fibroblastic growth factor (FGF)-2-stimulated endothelial cells.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were isolated and cultured. Groups were arranged in order to observe the impact of each individual substance alone, or under stimulation with statin on FGF-2-stimulated endothelial cells. Endothelial cells were stimulated with human growth factor (HGF), statins, methyl-β-cyclodextrin (β-MCD), and either farnesyl pyrophosphate (FPP) ammonium salt, or geranylgeranyl-pyrophosphate (GGPP), respectively. Cell proliferation analyses were performed 48 hours after stimulation and gaps between migration borders were used in migration analyses.

RESULTS

The statins showed significant antiproliferative and anti-migrative effects and inhibited the proliferative behavior of FGF-2. However, endothelial cell proliferation and migration were significantly increased after mevalonate co-incubation. Experiments with β-MCD indicated that the destruction of lipid rafts had a negative impact on the action of FGF-2. Stimulation of statin-incubated cells with FPP had no additional effect on proliferation or migration. Notably, although FGF-2 exerted a pro-migrative effect, the effect was not shown in the FPP + FGF-2 group. The anti-migrative actions of statins along with disruption of membrane integrity were reversed by the addition of GGPP.

CONCLUSION

The angiogenic effect of FGF-2 is suppressed through inhibition of the intracellular cholesterol biosynthesis via statins. Inhibitory effects of statins on FGF-2-stimulated HUVECs were observed to result from both the inhibition of isoprenylation and the destruction of lipid rafts on the cell membrane.

Importance of large conductance calcium-activated potassium channels (BKCa) in interleukin-1b-induced adhesion of monocytes to endothelial cells

OBJECTIVE

The present study investigated the role of the large conductance calcium-activated potassium channels (BKCa) in interleukin-1b (IL-1b) induced inflammation.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were isolated and cultured. Endothelial cell membrane potential measurements were accomplished using the fluorescent dye DiBAC4(3). The role of BKCa was assessed using iberiotoxin, a highly selective BKCa inhibitor. Changes in the calcium intracellular calcium were investigated using Fura-2-AM imaging. Fluorescent dyes DCF-AM and DAF-AM were further used in order to measure the formation of reactive oxygen species (ROS) and nitric oxide (NO) synthesis, respectively. Endothelial cell adhesion tests were conducted with BCECF-AM adhesion assay and tritium thymidine uptake using human monocytic cells (U937). Expression of cellular adhesion molecules (ICAM-1, VCAM-1) was determined by flow cytometer.

RESULTS

Interleukin-1b induced a BKCa dependent hyperpolarization of HUVECs. This was followed by an increase in the intracellular calcium concentration. Furthermore, IL-1b significantly increased the synthesis of NO and ROS. The increase of intracellular calcium, radicals and NO resulted in a BKCa dependent adhesion of monocytes to HUVECs. Endothelial cells treated with IL-1b expressed both ICAM-1 and VCAM-1 in significantly higher amounts as when compared to controls. It was further shown that the cellular adhesion molecules ICAM-1 and VCAM-1 were responsible for the BKCa-dependent increase in cellular adhesion. Additionally, inhibition of the NADPH oxidase with DPI led to a significant downregulation of IL-1b-induced expression of ICAM and VCAM, as well as inhibition of eNOS by L-NMMA, and intracellular calcium by BAPTA.

CONCLUSIONS

Activation of the endothelial BKCa plays an important role in the IL-1b-induced monocyte adhesion to endothelial cells.

Effect of bauhinia bauhinioides kallikrein inhibitor on endothelial proliferation and intracellular calcium concentration

OBJECTIVES

Proteinase inhibitors act as a defensive system against predators e.g. insects, in plants. Bauhinia bauhinioides kallikrein inhibitor (BbKI) is a serine proteinase inhibitor, isolated from seeds of Bauhinia bauhinioides and is structurally similar to plant Kunitz-type inhibitors but lacks disulfide bridges. In this study we evaluated the antiproliferative effect of BbKI on endothelial cells and its impact on changes in membrane potential and intracellular calcium.

MATERIALS AND METHODS

HUVEC proliferation was significantly reduced by incubation with BbKI 50 and 100 µM 12% and 13%. Furthermore, BbKI (100 µM) exposure caused a significant increase in intracellular Ca2+ concentration by 35% as compared to untreated control.

RESULTS

The intracellular rise in calcium was not affected by the absence of extracellular calcium. BBKI also caused a significant change in the cell membrane potential but the antiproliferative effect was independent of changes in membrane potential.

CONCLUSIONS

BBKI has an antiproliferative effect on HUVEC, which is independent of the changes in membrane potential, and it causes an increase in intracellular Ca2+.

Acute left main coronary artery occlusion

The treatment of an acute left main coronary artery occlusion still poses a challenge. In this case report we present a 50-year-old patient with an acute occlusion of the left main artery. After a successful angioplasty without "stenting" due to the complexity of the stenosis the patient underwent a successful bypass surgery. We discuss the therapeutic options of acute left main occlusion regarding medical, interventional and surgical options.

Deep vein thrombosis and novel oral anticoagulants: a clinical review

Deep vein thrombosis (DVT) is a common disease associated with high rates of mortality and significant morbidity. The diagnostic approach of DVT has evolved over the years. Algorithmical use of pretest probability, D-Dimer testing and ultrasonography allow safe and accurate investigation of DVT. The anticoagulation therapy, used to treat DVT, includes vitamin K antagonists (VKAs) and low-molecular-weight heparin (LMWH) or unfractionated heparin (UF). The duration of anticoagulation therapy depends on the cause of DVT and patient's clinical profile. Although these conventional therapies are effective, narrow therapeutic index, need for frequent monitoring and various food-drug interactions cause difficulties for patients. In recent decades, new oral anticoagulants have been developed. These drugs focus directly on inhibiting either Factor Xa (rivaroxaban, apixaban, edoxaban) or thrombin (dabigatran). In contrast to warfarin, these new agents have shorter half-life, fewer drug or food interactions, no necessity for a close monitoring and ease of administration. This review summarizes current knowledge about deep vein thrombosis and new treatment aspects with novel oral anticoagulants.

The effects of different types of statins on proliferation and migration of HGF-induced Human Umbilical Vein Endothelial Cells (HUVECs)

BACKGROUND AND AIM

Statins are HMG-CoA reductase inhibitors within the framework of cholesterol biosynthesis and used to lower the low-density lipoprotein (LDL). There are other aspects of statins can deploy a protective effect, even without the LDL's lowering. The aim of this study is to investigate the effects of different type of statins on proliferative and migrative behaviors of Hepatocyte Growth Factor (HGF) induced human umbilical vein endothelial cells (HUVECs).

MATERIALS AND METHODS

Human umbilical vein endothelial cells were isolated and cultured. Groups were designed in order to observe the effects of every individual substance. HUVECs were stimulated with HGF, statins and farnesylpyrophosphat ammonium salt (FPP) or geranylgeranyl-pyrophosphate (GGPP), respectively. Cell proliferations were counted 48 hours after initial stimuli and distances between migration fronts were used in migration analyses.

RESULTS

All types of statins showed significant anti-migrative and anti-proliferative characters. Simvastatin and fluvastatin but not cerivastatin, were able to inhibit the HGF-depending migration and showed a significant effect on the inhibition of the isoprenylation (GGPP). Only simvastatin influenced the HGF-depending migration via inhibiting the isoprenylation process through GGPP. Cerivastatin significantly decreased the proliferation and Fluvastatin significantly enhanced the migration behaviors of HUVECs when they were co-incubated with methyl-8-cyclodextrin (MCD).

CONCLUSIONS

Statins countermand the proproliferative and as well as the promigrative effect of HGF on HUVECs. The mechanisms which provoke this effect are dependent on the type of statin. Direct interactions of statins with lipid rafts play a significant role in the endothelial cell mechanisms.

Discovery of asymptomatic Krukenberg tumors diagnosed during caesarean section: therapy with hyperthermic intraperitoneal chemotherapy

We report a case of the discovery of asymptomatic Krukenberg tumors in a 37-year-old woman in the 37th week of pregnancy during caesarean section. Subsequent gastroscopy revealed an adenocarcinoma of the stomach as the primary tumor site. The patient was treated with hyperthermic intraperitoneal chemotherapy (HIPEC). Tumor surgery (Partial parietal peritonectomy and partial gastrectomy) and HIPEC treatment were successful, with no complications found during follow-up. Use of HIPEC seems to be a promising option after radical surgery, including its use in patients with gastric tumors that are in advanced stages, and use in patients who have tumors with poor prognoses, such as Krukenberg tumors.

Giant aneurysm of the right coronary artery with fistula to right atrium

Coronary artery aneurysms are rare entities with a prevalence of 0.15%-4.9%. Giant coronary artery aneurysms are known as more than 2 to 5 cm in size. We present a case of 74 year-old female who was admitted to our clinic with chest pain and dyspnea. Coronary angiography demonstrated a giant right coronary artery (RCA) aneurysm with a significant left-to-right shunt. The patient underwent an open heart surgery. During the exploration, an aneurysm of 40 mm in diameter of the RCA was seen. The aneurysmatic RCA was excluded and continuously closed with the support of intra-aortic balloon pump (IABP). The patient was discharged on the 13th postoperative day without any complication.

Regulation of monocyte/macrophage function by factor VII activating protease (FSAP)

OBJECTIVE

Factor VII activating protease (FSAP) is a novel regulator of vascular inflammation and hemostasis. However, the molecular mechanism by which circulating FSAP influences inflammatory events and progression of atherosclerosis is not yet entirely understood. Here we have investigated the influence of FSAP on monocyte/macrophage functions.

METHODS

We stimulated human monocyte-derived macrophages with FSAP and analyzed their cellular responses.

RESULTS

FSAP induced IκB-dependent NF-κB activation in a time- and concentration-dependent fashion. FSAP also activated the phosphorylation and proteolytic degradation of the inhibitor protein IκBα. The phosphorylation of the p65 subunit of NF-κB was induced by FSAP, which is known to contribute to the enhancement of DNA-binding activity of NF-κB. Concomitantly, FSAP up-regulated the expression of pro-inflammatory cytokines, matrix metalloproteinases, cell adhesion molecules and tissue factor. In the presence of FSAP there was increased monocytes adhesion and transendothelial migration in a beta2 integrin dependent manner.

CONCLUSIONS

Our findings suggest that FSAP activates the NF-κB pathway and the associated downstream pro-inflammatory factors in monocytic cells. This adds to a spectrum of FSAP effects on the vascular system that may explain its association with cardiovascular diseases.

Effects of caffeic acid phenethyl ester (CAPE) on membrane potential and intracellular calcium in human endothelial cells

BACKGROUNG AND OBJECTIVES: Caffeic acid phenethyl ester (CAPE) is an active component of the resin propolis obtained from beehives. Propolis has a long history of medicinal use and a number of studies have already reported on some of its pharmaceutical properties. This study aimed to explore the effects of CAPE on the cytosolic Ca2+ concentration, cell proliferation, membrane potential and NO levels in human endothelial cells.

MATERIALS AND METHODS

Isolated human umbilical vein endothelial cells (HUVEC) were incubated with CAPE (1-100 µM) at 37°C for 48 hours. Cell proliferation was estimated by counting cell numbers with use of a Neubauer chamber. The effect of CAPE (1-100 µM) on the membrane potential was measured with the fluorescence dye DIBAC4(3) whereas its effect on the cytosolic Ca2+ concentration was measured by use of the fluorescence probe Fluo-3 AM (Invitrogen, Leiden, Netherlands). NO production was assayed using the flourophore DAF~AM (Invitrogen, Leiden, Netherlands). Changes in fluorescence intensity was determined with the GENios plate reader (Genios, Tecan, Austria).

RESULTS

A dose-dependent hyperpolarization of the endothelial cell membrane was observed with CAPE stimulation. The initial increase in the intracellular Ca2+ concentration showed a subsequent decrease over time. CAPE stimulation also resulted in an increase in NO production; however, at higher doses a decrease in NO levels was observed. HUVEC proliferation was inhibited by CAPE.

CONCLUSIONS

Here we report on the effect of CAPE stimulation on the cytosolic Ca2+ concentration, cell proliferation, membrane potential and NO production in HUVEC in a dose-dependent manner. These findings provide important insights into some potential key roles that both calcium and the membrane potential play in the CAPE activation of endothelial cells in a concentration-dependent manner.

The antiproliferative effect of pinostrobin on human umbilical vein endothelial cells (HUVEC)

BACKGROUND

Atherosclerosis and stent re-stenosis are problems that are accompanied with high morbidity and mortality. Endothelial cell proliferation plays a role in both diseases, so the quest for potent inhibitors is still ongoing.

AIM

The flavonoid pinostrobin previously showed cytotoxic effects on different cell lines. In this investigation, we tested the antiproliferative effect of pinostrobin on human umbilical vein endothelial cells (HUVEC).

MATERIALS AND METHODS

The effect of pinostrobin on human umbilical vein endothelial cells after 1 hour and after 48 hours of treatment was tested. A dose- and time-dependent antiproliferative effect of pinostrobin was observed.

RESULTS

After 1 hour of treatment, no significant differences between the control group and the cells treated with pinostrobin could be detected. After 48 h of pinostrobin treatment, the number of cells decreased significantly. Higher doses had stronger inhibitory effects on the proliferation. Furthermore, we tested the change of membrane potential on cells that were treated with different concentrations of pinostrobin. We could show that the change of membrane potential was also time- as well as dose-dependent.

CONCLUSIONS

Our hypothesis is that pinostrobin leads to depolarisation of the cell potential of endothelial cells. Since the membrane potential remains less negative, this could lead to instability of the membrane, resulting in cell death.

Ultrasonography and magnetic resonance imaging findings of abdominal complications of cystic fibrosis

In this study, our aim is to discuss the imaging findings of the abdominal complications seen in Cystic Fibrosis (CF), with ultrasonography (US) and magnetic resonance imaging (MRI). Our first case, a 22 year-old female showed changes characterized by severe biliary involvement such as cholelithiasis and cholangitis. Our second case was a 36 year-old male with severe hepatic manifestations. In this case signs of severe cirrhosis, portal hypertension and marked splenomegaly were seen. Micro-gallbladder, cholecystolithiasis and diffuse fatty infiltration of the pancreas were seen in both cases.

IN CONCLUSION

US and MRI are effective and noninvasive imaging techniques to evaluate the abdominal complications of cystic fibrosis.

Influence of time between last myocardial infarction and prophylactic implantable defibrillator implant on device detections and therapies. "Routine Practice" data from the SEARCH MI registry

BACKGROUND

A multicenter European Registry, SEARCH-MI, was instituted in the year 2002 in order to assess patients' outcomes and ICD interventions in patients with a previous MI and depressed LV function, treated with an ICD according to MADIT II results. In this analysis, we evaluate the influence of the time elapsed between last myocardial infarction (MI) and prophylactic cardioverter defibrillator (ICD) implant on device activations.

METHODS

643 patients with left ventricular dysfunction (mean LVEF 26 ± 5%) and NYHA class I-III were prospectively followed for 1.8 ± 1.2 years in a multicenter registry. The population was divided into 3 groups according to the time between last MI and ICD implant: [1] from 40 days to less than 1.5 years; [2] from 1.5 to less than 7 years and [3] at least 7 years.

RESULTS

The cumulative incidence of ventricular tachyarrhymias and appropriate device therapy (ATP or shock) were higher in patients implanted longer time from last MI (Gray's Test p=0.002 and p=0.013 respectively). No significant differences were seen in all cause mortality (Gray's Test p=0.618) or sudden cardiac death across the MI stratification groups (Gray's Test p=0.663).

CONCLUSIONS

Patients implanted with an ICD longer after the MI have a higher chance of presenting ventricular tachyarrhythmias and appropriate ICD therapy, while no differences were seen in overall mortality. These observations may be important for improving patient targeting in sudden death prevention.

Circulating factor VII activating protease (FSAP) is associated with clinical outcome in acute coronary syndrome

BACKGROUND

Factor VII activating protease (FSAP) is a circulating serine protease strongly expressed in unstable plaques and may serve as a marker of plaque destabilization. The aim of this study was to examine the relation between plasma concentrations of FSAP and clinical instability and outcome in coronary artery disease (CAD).

METHODS AND RESULTS

Circulating FSAP concentration and activity, as well as FSAP mRNA expression in monocytes, were measured in 231 sequential patients who underwent coronary angiography because of stable angina pectoris (n=50), unstable angina pectoris (n=43), or acute myocardial infarction (n=87). FSAP activity, but not FSAP antigen concentration, was elevated in patients with CAD compared with a control group. Elevated FSAP activity (≥1.035 plasma equivalent units [PEU]/ml) indicated a significantly increased risk of death or non-fatal myocardial infarction during 1 year of follow-up as compared with patients with low activity of FSAP (odds ratio 1.895 [95% confidence interval 1.093-3.283]; P=0.023). Furthermore, there were no significant changes in the FSAP expression in monocytes from CAD and control subjects in the basal state but there were differences after stimulation with proinflammatory factors.

CONCLUSIONS

Plasma FSAP activity was significantly increased in patients with acute coronary syndrome and may be involved in the pathogenesis of these conditions. High levels of FSAP activity were predictive of adverse events during follow-up, suggesting its potential role in risk stratification and clinical management of CAD patients.

Interplay between Ca2+ cycling and mitochondrial permeability transition pores promotes reperfusion-induced injury of cardiac myocytes

Uncontrolled release of Ca²⁺ from the sarcoplasmic reticulum (SR) contributes to the reperfusion-induced cardiomyocyte injury, e.g. hypercontracture and necrosis. To find out the underlying cellular mechanisms of this phenomenon, we investigated whether the opening of mitochondrial permeability transition pores (MPTP), resulting in ATP depletion and reactive oxygen species (ROS) formation, may be involved. For this purpose, isolated cardiac myocytes from adult rats were subjected to simulated ischemia and reperfusion. MPTP opening was detected by calcein release and by monitoring the ΔΨ_m. Fura-2 was used to monitor cytosolic [Ca²⁺]_i or mitochondrial calcium [Ca²⁺]_m, after quenching the cytosolic compartment with MnCl₂. Mitochondrial ROS [ROS]_m production was detected with MitoSOX Red and mag-fura-2 was used to monitor Mg²⁺ concentration, which reflects changes in cellular ATP. Necrosis was determined by propidium iodide staining. Reperfusion led to a calcein release from mitochondria, ΔΨ_m collapse and disturbance of ATP recovery. Simultaneously, Ca²⁺ oscillations occurred, [Ca²⁺]_m and [ROS]_m increased, cells developed hypercontracture and underwent necrosis. Inhibition of the SR-driven Ca²⁺ cycling with thapsigargine or ryanodine prevented mitochondrial dysfunction, ROS formation and MPTP opening. Suppression of the mitochondrial Ca²⁺ uptake (Ru360) or MPTP (cyclosporine A) significantly attenuated Ca²⁺ cycling, hypercontracture and necrosis. ROS scavengers (2-mercaptopropionyl glycine or N-acetylcysteine) had no effect on these parameters, but reduced [ROS]_m. In conclusion, MPTP opening occurs early during reperfusion and is due to the Ca²⁺ oscillations originating primarily from the SR and supported by MPTP. The interplay between Ca²⁺ cycling and MPTP promotes the reperfusion-induced cardiomyocyte hypercontracture and necrosis. Mitochondrial ROS formation is a result rather than a cause of MPTP opening.

Diagnostic value of dynamic contrast-enhanced magnetic resonance imaging in the evaluation of the biliary obstruction

Purpose. In this study, our purpose was to investigate the diagnostic efficacy of the dynamic contrast-enhanced magnetic resonance imaging (MRI) method in the patients with bile duct obstruction. Materials and Methods. 108 consecutive patients (53 men, 55 women, mean age; 55.77 ± 14.62, range 18–86 years) were included in this study. All the patients underwent conventional upper abdomen MRI using intravenous contrast material (Gd-DTPA) and MRCP in 1.5 Tesla MRI scanner. MRCP images were evaluated together with the T1 and T2w images, and both biliary ducts and surrounding tissues were examined for possible pathologies that may cause obstruction. Results. MRI/MRCP findings compared with final diagnoses, MRI/MRCP in the demonstration of bile duct obstruction sensitivity 96%, the specificity 100%, and accuracy 96.3%, in the detection of presence and level of obstruction, the sensitivity 96.7%, specificity 100%, and accuracy 97.2%, in the diagnosis of choledocholithiasis, the sensitivity 82.3%, specificity 96%, and accuracy 91.7%, and in the determination of the character of the stenosis, sensitivity 95.6%, specificity 91.3%, and accuracy 94.5% were found. Conclusion. The combination of dynamic contrast-enhanced MRI and MRCP techniques in patients with suspected biliary obstruction gives the detailed information about the presence of obstruction, location, and causes and is a highly specific and sensitive method.

Asymmetrically increased uptake in upper extremities on (99m)Tc-MDP bone scintigraphy caused by intra-arterial injection: different uptake patterns in three cases

Unexpected findings on bone scintigraphy such as asymmetrical uptake in extremities may cause confusion for the diagnosis. The authors describe three cases of accidental intraarterial injection of Tc-(99m) methylene diphosphonate ((99m)Tc-MDP) on the antecubital region and discuss the findings and differential diagnosis.

Tako-tsubo cardiomyopathy in a 92-year old woman

Tako-Tsubo cardiomyopathy (TTC) is an acute reversible cause of segmental myocardial dysfunction that is poorly understood and cannot be explained by the occlusion of a single coronary vessel. Its clinical presentation is similar to that of acute coronary syndrome and is often precipitated by a severe psychological or physical stress.