Association of serum IGF1 with endothelial function: results from the population-based study of health in Pomerania

OBJECTIVE

IGF1 mediates multiple physiological and pathophysiological responses in the cardiovascular system. The aim of this study was to analyze the association between serum IGF1 as well as IGF-binding protein 3 (IGFBP3) levels and endothelial function measured by flow-mediated dilation (FMD).

DESIGN

Cross-sectional population-based observational study.

METHODS

The study population comprised 1482 subjects (736 women) aged 25-85 years from the Study of Health in Pomerania. Serum IGF1 and IGFBP3 levels were determined by chemiluminescence immunoassays. FMD measurements were performed using standardized ultrasound techniques. FMD values below the sex-specific median were considered low.

RESULTS

In males, logistic regression analyses revealed an odds ratio (OR) of 1.27 (95% confidence interval (CI) 1.07-1.51; P=0.008) for decreased FMD for each decrement of IGF1 s.d. after adjustment for major cardiovascular confounders. In females, no significant relationship between serum IGF1 and FMD was found (OR 0.88, CI 0.74-1.05; P=0.147). After exclusion of subjects with the current use of antihypertensive medication, these findings were similar (males: OR 1.40, CI 1.12-1.75; P=0.003; females: OR 0.95, CI 0.77-1.16; P=0.595). There was no association between serum IGFBP3 levels and FMD in both sexes.

CONCLUSIONS

Low serum IGF1 levels are associated with impaired endothelial function in males. In women, serum IGF1 is not associated with endothelial function.

Cardiopulmonary bypass, hemolysis, free iron, acute kidney injury and the impact of bicarbonate

Cardiac surgery with cardiopulmonary bypass (CPB) is one of the most common major surgical procedures worldwide often associated with acute kidney injury (AKI)--a frequent and serious complication of cardiac surgery and affects up to 50% of patients. The major determinants of AKI after CPB are hemodynamic and inflammatory factors and the release of heme and labile iron contributing to oxidation from reactive oxygen species. The generation of reactive oxygen species is catalyzed by free labile iron which is most active at acid pH. To date, no simple, safe, and effective intervention to prevent CPB-associated AKI in a broad patient population has been found. However, there is recent evidence from experimental and clinical studies that sodium bicarbonate protects from oxidant renal injury in different settings, at least in part, by scavenging of hydroxyl radicals, peroxynitrite and other reactive species.

Development of the endothelium: an emphasis on heterogeneity

The endothelium is composed of specialized epithelial cells that line the vasculature, the lymph vessels, and the heart. These endothelial cells are characterized by their stratification and are connected via intercellular junctions that confer specific permeability. Although all endothelium acts as a barrier, considerable heterogeneity exists among different organs and even within vessels. During development, the endothelial cells are specified before they migrate to their final destination, and then they commit to an arterial or venous fate. From the venous endothelial cell population, a subset of cells is further specified as lymphatic endothelium. The endothelium can be highly permeable, as in the lymph vessels, or impenetrable, as in the blood-brain barrier. These differences arise during development and are orchestrated through a series of signaling pathways. This review details how endothelial cells arise and are directed to their specific fate, specifically targeting what differentiates endothelial populations.

Mechanism of alpha-1 antitrypsin endocytosis by lung endothelium

The integrity of lung alveoli is maintained by proper circulating levels of alpha-1 antitrypsin (A1AT). Next to cigarette smoking, A1AT deficiency is a major risk factor for lung emphysema development. We recently reported that in addition to neutralizing neutrophil elastases in the extracellular compartment, A1AT is internalized by lung endothelial cells and inhibits apoptosis. We hypothesized that the intracellular uptake of A1AT by endothelial cells may be required for its protective function; therefore, we studied the mechanisms of A1AT internalization by primary rat lung microvascular endothelial cells and the effect of cigarette smoke on this process both in vitro and in vivo (in mice). Purified A1AT was taken up intracellularly by endothelial cells in a time-dependent, dose-dependent, and conformer-specific manner and was detected in the cytoplasm of endothelial cells of nondiseased human lung sections. Despite a critical role for caveoli in endothelial cell endocytosis in general, specific inhibition of clathrin-mediated, but not caveoli-mediated, endocytosis profoundly decreased A1AT internalization and reversed the A1AT's antiapoptotic action. Further more, A1AT associated with clathrin heavy chains, but not with caveolin-1 in the plasma membrane fraction of endothelial cells. Interestingly, cigarette smoke exposure significantly inhibited A1AT uptake both in endothelial cells and in the mouse lung and altered the intracellular distribution of clathrin heavy chains. Our results suggest that clathrin-mediated endocytosis regulates A1AT intracellular function in the lung endothelium and may be an important determinant of the serpin's protection against developing cigarette smoke-induced emphysema.

Early and long-term effects of radiation on intercellular adhesion molecule 1 (ICAM-1) expression in mouse urinary bladder endothelium

The aim was to assess the effect of irradiation on intercellular adhesion molecule 1 (ICAM-1) expression in endothelial cells of vessels in mouse urinary bladder and to compare endothelial ICAM-1 expression with changes in bladder function (storage capacity) during the early and late radiation response phases. Female C3H/Neu mice were irradiated with doses of either 20 or 0 Gy. For assessment of ICAM-1 expression, which was measured by the intensity of the immunohistochemical staining signal in bladder endothelium, an arbitrary semiquantitative score (0 - 3) was applied. Bladder storage function was assessed by transurethral cystotonometry. A positive functional radiation response, defined as a reduction in bladder capacity by > 50%, between days 0 and 15 or 16 and 30 was found in 40 and 64% of the animals, respectively. A late functional response was observed in 71% of the animals sacrificed after day 180. Minor constitutive expression of ICAM-1 was observed in bladder endothelial cells. After irradiation, an increase in staining signal by day 2, with a maximum on day 4, and on days 16 - 28 was found, which preceded the functional radiation effects. A permanent increase in ICAM-1 staining signal was observed in the late phase on top of an age-related rise. ICAM-1 expression was significantly higher in animals with a positive late response on day 90, i.e. during the initial late phase. Irradiation induces significant early and chronic variations in ICAM-1 expression in bladder endothelium, which preceded the functional response. This suggests that endothelial ICAM-1 is involved in the pathogenesis of both the early and late phases of radiation-induced urinary bladder effects.

Corneal endothelial permeability following storage in moist chamber and MK medium

Rabbit corneal endothelial permeability to sucrose and dextran was determined after storage in moist chamber or MK medium. When compared to fresh rabbit corneas there was no statistically significant difference in endothelial permeability to these two solutes after both types of storage for periods up to ten days.

On some factors related to the pathogenesis of diabetic angiopathy

The deterioration of the circulation in small and large vessels in diabetes seems to be related to abnormalities of the function of the endothelial cells and of the platelets. The endothelial factor VIII R:Ag, enhancing platelet adhesion, is increased, while fibrinolysis is decreased. The balance between thromboxane (platelet-aggregating) and prostacyclin (desaggregating) is also shifted in a similar way. These changes all favour increased deposition and delayed removal of platelets and fibrin on the intima, and they might contribute markedly to the development of diabetic angiopathy. Some new drugs seem to normalize the endothelial fibrinolytic activity, and long term studies are in progress to evaluate if this improvement is parallelled by a delayed or absent development of vascular complications.

Vascular protection by tetrahydrobiopterin: progress and therapeutic prospects

Tetrahydrobiopterin (BH4) is an essential cofactor required for the activity of endothelial nitric oxide (NO) synthase. Suboptimal concentrations of BH4 in the endothelium reduce the biosynthesis of NO, thus contributing to the pathogenesis of vascular endothelial dysfunction. Supplementation with exogenous BH4 or therapeutic approaches that increase endogenous amounts of BH4 can reduce or reverse endothelial dysfunction by restoring production of NO. Improvements in formulations of BH4 for oral delivery have stimulated clinical trials that test the efficacy of BH4 in the treatment of systemic hypertension, peripheral arterial disease, coronary artery disease, pulmonary arterial hypertension, and sickle cell disease. This review discusses ongoing progress in the translation of knowledge, accumulated in preclinical studies, into the clinical application of BH4 in the treatment of vascular diseases. This review also addresses the emerging roles of BH4 in the regulation of endothelial function and their therapeutic implications.

Quercetin: potentials in the prevention and therapy of disease

PURPOSE OF REVIEW

Quercetin is discussed since several decades as a multipotent bioflavonoid with great potential for the prevention and treatment of disease. In the current review, we present the most recent findings on quercetin with regard to the pharmacology, the in-vitro and in-vivo effects in different cell systems and animal models, and the clinical effects in humans.

RECENT FINDINGS

Quercetin bioavailability has been underestimated in the past and can be improved by food matrix components or particular delivery forms. Among the biological effects of particular relevance, the antihypertensive effects of quercetin in humans and the improvement of endothelial function should be emphasized. Together with its antithrombotic and anti-inflammatory effects, the latter mainly mediated through the inhibition of cytokines and nitric oxide, quercetin is a candidate for preventing obesity-related diseases. Most exiting are the findings that quercetin enhances physical power by yet unclear mechanisms. The anti-infectious and immunomodulatory activities of quercetin might be related to this effect.

SUMMARY

Quercetin is a most promising compound for disease prevention and therapy; however, many of the effects still need confirmation by human intervention trials.

Adiponectin deficiency promotes endothelial activation and profoundly exacerbates sepsis-related mortality

Sepsis is a multifactorial, and often fatal, disorder typically characterized by widespread inflammation and immune activation with resultant endothelial activation. In the present study, we postulated that the adipokine adiponectin serves as a critical modulator of survival and endothelial activation in sepsis. To this aim, we evaluated both loss-of-function (adiponectin gene-deficient mice) and subsequent gain-of-function (recombinant adiponectin reconstitution) strategies in two well-established inflammatory models, cecal ligation perforation (CLP) and thioglyocollate-induced peritonitis. Adipoq(-/-) mice, subjected to CLP, exhibited a profound ( approximately 8-fold) reduction in survival compared with their wild-type Adipoq(+/+) littermates after 48 h. Furthermore, compared with wild-type controls, thioglycollate challenge resulted in a markedly greater influx of peritoneal neutrophils in Adipoq(-/-) mice accompanied by an excess production of key chemoattractant cytokines (IL-12p70, TNFalpha, MCP-1, and IL-6) and upregulation of aortic endothelial adhesion molecule VCAM-1 and ICAM-1 expressions. Importantly, all of these effects were blunted by recombinant total adiponectin administration given 3 days prior to thioglycollate challenge. The protective effects of adiponectin were ascribed largely to higher-order adiponectin oligomers, since administration of recombinant C39A trimeric adiponectin did not attenuate endothelial adhesion molecule expression in thioglycollate-challenged Adipoq(-/-) mice. These data suggest a critical role of adiponectin as a modulator of survival and endothelial inflammation in experimental sepsis and a potential mechanistic link between adiposity and increased sepsis.

Augmentation of angiogenic and endothelial associated gene expression by EDM50 in human chorion-derived stem cells

The objective of this study was to investigate the angiogenic potential of human chorion-derived stem cells (CDSC) cultured in medium containing bFGF and VEGF (EDM50). Total RNA was extracted from cells cultured in FD+10% FBS and EDM50. Quantitative RT-PCR was carried out to score the differential mRNA expression of genes involve in angiogenesis and endothelial differentiation. Our finding demonstrated that all angiogenic and endothelial associated genes were expressed higher in EDM50. Expression level of ANG-1, eNOS and VEGFR2 were significantly higher in EDM50 compared to FD+10% FBS. Our results suggested that human CDSC cultured in EDM50 can be used for angiogenesis purpose in regenerative medicine.

Corneal endothelial cell loss between the Kongsap manual phacofragmentation and phacoemulsification

OBJECTIVE

To compare corneal endothelial cell loss between the Kongsap manual phacofragmentation and phacoemulsification.

MATERIAL AND METHOD

One hundred two eyes with age-related cataract were randomized to undergo either the Kongsap manual phacofragmentation (Group 1, 52 eyes) or phacoemulsification surgery (Group 2, 50 eyes) with implantation of a posterior chamber, foldable, acrylic intraocular lens performed by one surgeon. The main parameters were corneal endothelial cell density (ECD), best corrected visual acuity (BCVA), and intraoperative and postoperative complications. Follow-up visits were scheduled at 1, 4, and 12 weeks.

RESULTS

Pre-operatively, the mean ECD in Group 1 was 2,350 +/- 229 cells/mm2 and in Group 2 was 2,429 +/- 263 cells/mm2 (p = 0.112). Mean ECD decrease was 7.61% in Group 1 and 7.19% in Group 2 at the end of 12 weeks. The 95% confidence intervals of the mean differences of the endothelial cell loss at 4 weeks and 12 weeks after surgery were -1.87 to 2.04% and -2.77 to 3.63%, respectively. Mean best-corrected visual acuity at the end of 4 weeks was 0.88 +/- 0.22 in Group 1 and 0.82 +/- 0.24 in Group 2 (p = 0.117). There was no statistical difference between the groups in intra-operative and postoperative complications (p > 0.05).

CONCLUSION

The corneal endothelial cell loss after cataract surgery with the Kongsap manual phacofragmentation is equivalent to those of phacoemulsification and both surgical techniques allowed excellent visual results.

Physical factors and angiogenesis

Angiogenesis consists of migration and mitosis of blood vessels and lymphatic endothelium. The control of angiogenesis is multifactorial, being determined by physical as well as chemical factors. The physical factors include contact, binding, scaffolds and barriers, attachment, spreading, lining and even phagocytosis. The vascular pattern in the skin suggests that epithelium is a principal influence on angiogenesis and that it may guide or obstruct the growth of its blood supply, using fibrin, collagen, elastin and ground substance as a means of exerting control. The hamster cheek pouch and the chorioallantoic membrane have been used to demonstrate that epithelium exerts both chemical and physical effects. There is a need for further investigation of mechanisms underlying the conversion of physical factors into chemical signals. They probably include the release of proteases or their inhibitors during the distortion of fibrillar material.

Cell interactions in post-traumatic fibrosis

Models of reparative fibrosis, or wound healing, disclose a basic spatial relationship between inflammatory cells, fibroblasts, dividing fibroblasts and angiogenic endothelial cells. Many components of the extracellular fluid, especially steep gradients of PO2, PCO2, pH, glucose and lactate, have been measured. After components of coagulation play out their role in the first few days after injury, macrophages sense excitatory substances and signs of respiratory distress, and secrete chemoattractants for endothelial cells and fibroblasts. If excitatory substances (such as silica) are eliminated, active fibrosis ends with the restoration of the energy supply. Some of the mitogens and chemoattractants acting as intercellular messengers between these cells have been isolated and identified.

Apigenin inhibits platelet adhesion and thrombus formation and synergizes with aspirin in the suppression of the arachidonic acid pathway

Previous studies using washed platelets demonstrated that certain flavonoids inhibit platelet function through several mechanisms including blockade of TxA(2) receptors (TPs). We aimed to analyze the binding capacity of flavonoids to TPs in platelet rich plasma (PRP), investigated their effect in flowing blood, and evaluated the ability of apigenin to improve the efficacy of aspirin in the inhibition of platelet aggregation. The binding of flavonoids to TPs in PRP was explored using binding assays and the TP antagonist [ (3)H]SQ29548. Effects of flavonoids on platelet adhesion were assessed using arterial subendothelium with annular plate perfusion chambers, and global evaluation of apigenin on high-shear-dependent platelet function was determined by the PFA-100. To evaluate the ability of apigenin to potentiate the effect of aspirin, arachidonic acid-induced platelet aggregation was measured prior to and after consumption of subaggregatory doses of aspirin in the presence or absence of apigenin. Binding assays revealed that apigenin was an efficient competitor of [ (3)H]SQ29548 binding to PRP ( K i = 155.3 +/- 65.4 microM), and perfusion studies showed that apigenin, genistein, and catechin significantly diminished thrombus formation when compared to control (26.2 +/- 3.8, 33.1 +/- 5.2, and 26.2 +/- 5.2 vs 76.6 +/- 2.6%, respectively; p < 0.05). Apigenin, similarly to the TP antagonist SQ29548, significantly prolonged collagen epinephrine-induced PFA-100 closure time in comparison to the control and, when added to platelets that had been exposed in vivo to aspirin, potentiated its inhibitory effect on platelet aggregation. The inhibitory effect of some flavonoids in the presence of plasma, particularly apigenin, might in part rely on TxA(2) receptor antagonism. There is a clear increase in the ex vivo antiplatelet effect of aspirin in the presence of apigenin, which encourages the idea of the combined use of aspirin and certain flavonoids in patients in which aspirin fails to properly suppress the TxA(2) pathway.

Review article: steroid hormones and uterine vascular adaptation to pregnancy

Pregnancy is a physiological state that involves a significant decrease in uterine vascular tone and an increase in uterine blood flow, which is mediated in part by steroid hormones, including estrogen, progesterone, and cortisol. Previous studies have demonstrated the involvement of these hormones in the regulation of uterine artery contractility through signaling pathways specific to the endothelium and the vascular smooth muscle. Alterations in endothelial nitric oxide synthase expression and activity, nitric oxide production, and expression of enzymes involved in PGI(2) production contribute to the uterine artery endothelium-specific responses. Steroid hormones also have an effect on calcium-activated potassium channel activity, PKC signaling pathway and myogenic tone, and alterations in pharmacomechanical coupling in the uterine artery smooth muscle. This review addresses current understanding of the molecular mechanisms by which steroid hormones including estrogen, progesterone, and cortisol modulate uterine artery contractility to alter uterine blood flow during pregnancy with an emphasis on the pregnant ewe model.

[Causes and mechanisms of systemic vasculitides]

Multiple mechanisms contribute to the pathogenesis of systemic vasculitides: 1. vasculitides resulting from the deposition of circulating immune complexes, comprising polyarteritis nodosa associated with hepatitis B virus infection, cryoglobulinemia associated systemic with vasculitides, mainly the consequence of hepatitis C virus infection, and Schonlein Henoch purpura, which results from the deposition in the mesangium and vessels of IgA forming complexes; 2. vasculitides associated with anti-neutrophil cytoplasm antibodies (ANCA), comprising Wegener's granulomatosis associated with anti-proteinase 3 ANCA, and microscopic polyangiitis and Churg-Strauss syndrome, associated with anti-myeloperoxydase ANCA. The pathogenic role of ANCA has been demonstrated in vitro and in vivo in the case of anti-myéloperoxydase antibodies, whereas it has only been demonstrated in vitro in the case of anti-proteinase 3 antibodies; 3. polyarteritis nodosa unrelated to viral infection results from rheologic phenomenon that explain the localisation of vasculitis lesions at the bifurcation of arteries and the presence of microaneurysm.

Improved endothelial function following a 14-month resistance exercise training program in adults with type 2 diabetes

OBJECTIVE

We examined the effect of a 14-month progressive resistance training (PRT) program on endothelial function in both a supervised training (Center) group and non-supervised training (Home) group of patients with type 2 diabetes. We studied 28 men and women with type 2 diabetes who participated in a 14-month PRT involving an initial 2-month supervised program and a 12-month maintenance program.

METHODS

Endothelial function testing was performed through laser doppler flow responses in the skin microcirculation to iontophoresis of acetylcholine (ACh) and sodium nitroprusside (NaNP) and doses of 4, 8 and 16mC were used. Measurements of vascular response (VR), HbA1c, weight and blood pressure were performed at 0, 2 and 14 months.

RESULTS

VR to ACh and NaNP was significantly increased at 14 months compared with baseline in both the Center and Home groups. However, no between-group differences were observed. A significant correlation was observed between HbA1c and VR to ACh at baseline and 8 weeks using 8mC dose of ACh. There was a strong correlation between HbA1c at baseline and VR at 14 months using all three doses of ACh (4mC:r=-0.546, p=0.003, 8mC:r=-0.470, p=0.002, 16mC:r=-0.547, p=0.006).

CONCLUSIONS/INTERPRETATION

Endothelial function is improved following 14 months of PRT in type 2 diabetes both in a supervised and non-supervised program. Strong correlations with HbA1c including initial HbA1c levels suggest that glycemic control may be an important factor in long-term regulation of endothelial function.

Does tourniquet application alter the nitrergic responses of rabbit corpus cavernosum penis? A functional study

OBJECTIVE

To investigate the effects of short and long periods of tourniquet application on corporal nerves, endothelium and smooth muscle responses.

METHODS

After the rabbits were anesthetized with xylazine (5 mg/kg) and ketamine hydrochloride (35 mg/kg), a standard rubber circular band was applied to the base of the penis. After waiting for 20, 40 and 60 min, the tourniquets were removed and the penil tissue was reperfused for 5 min. In all groups, relaxation [carbachol, sodium nitroprusside (SNP) and electrical field stimulation (EFS) and contraction (phenylephrine and EFS)] responses were examined. In another set of experiments, the rabbits were killed 24 h after the tourniquet period of 60 min and carbachol-induced relaxation responses were obtained.

RESULTS

SNP- and EFS-induced relaxation responses were similar in all groups. Carbachol-induced relaxation responses were not altered in tissues from 20 min tourniquet group, but they were significantly reduced in tissues from 40 and 60 min tourniquet group compared to that from control group. The impaired endothelium-mediated relaxation responses did not return to control levels after 24 h of reperfusion period. Neither phenylephrine nor EFS-mediated contraction responses were altered with tourniquet application.

CONCLUSIONS

The results suggest that long period of tourniquet application altered endothelium-dependent muscarinic receptor-mediated relaxation responses. This is the first functional study that examined the effects of tourniquet application on corpus cavernosum tissue. In conclusion, it can be suggested that if tourniquet is necessary in penile surgery the application time of up to 20 min is more appropriate instead of prolonged usage.

Tetrahydrobiopterin

The endothelium plays a pivotal role in vascular physiology through a variety of factors, foremost of which is nitric oxide (NO). However, the biochemical mechanisms leading to reduced NO availability and subsequent endothelial dysfunction are not clearly understood. Tetrahydrobiopterin (BH(4)) is an essential cofactor for endothelial NO synthase. Recent preclinical and clinical studies in patients with cardiovascular risk and disease support the central role of reduced BH(4) availability in decreased NO production. This has led to BH(4) supplementation emerging as a possible therapy for conditions characterized by endothelial dysfunction (eg, hypertension, hypercholesterolemia, diabetes, and vascular disease states), and those caused by smoking and aging. Recent advances in drug formulation of BH(4) now offer the potential for better clinical understanding of endothelial function in human health and disease.