Physicochemical properties of arterial elastin and its associated glycoproteins

Microfibrillar glycoproteins are a significant component of vascular elastic tissue, but little is known about their contribution to vascular physiology and pathology. We have investigated some physicochemical properties of the glycoproteins that may be pertinent to these roles. Because of the difficulty in isolating intact glycoproteins in a form and quantity suitable for physicochemical examination, we based our analysis on a comparison of the properties of porcine thoracic aorta and pulmonary artery extracted with GuHCl and collagenase (preparation GC) and after further treatment with dithioerythritol to remove glycoproteins (preparation GC/DTE). Amino acid analysis showed that GC/DTE had the amino acid composition of pure elastin while GC contained a higher proportion of polar amino acids, particularly in the aortic preparation. GC stained with alcian blue, particularly in the intimal region, but GC/DTE did not. GC had a higher water content and a slower viscoelastic response and the circumferential elastic modulus was approximately 50% lower (whether expressed in terms of sample weight or elastin content). Clearly, therefore, the microfibrils do not stiffen the network and may prevent the alignment of elastin fibers in the circumferential direction. Their effect on hydration may arise either because they impose mechanical constraints on the geometry of the network or because they modify the inter‐ and intramolecular hydrophobic or electrostatic interactions that influence the tissue organization and hydration. Molecular probe measurements of the intrafibrillar pore structure using radiolabeled and fluorescent probes showed that removal of the microfibrils caused a slight decrease in the extrafibrillar water space and a larger decrease in the intrafibrillar water space. Sucrose, a small probe molecule, was able to penetrate most of the intrafibrillar water space when microfibrils were present but was virtually excluded when they were not. Potentiometric titration and radiotracer assays of ion binding both showed that the microfibrils contribute a considerable negative charge (−9 μmoles/g wet tissue in the aortic preparation and −16 μmoles/g wet weight in the pulmonary artery) and increase calcium binding by approximately 30%. © 1999 John Wiley & Sons, Inc. Biopoly 49: 255–265, 1999     

ShRNA knock‐down of CXCR7 inhibits tumour invasion and metastasis in hepatocellular carcinoma after transcatheter arterial chemoembolization

To investigate the effects of lentiviral vector‐mediated shRNA suppressing CXCR7 on tumour invasion and metastasis in hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE). HCCLM3 cell lines were cultured and assigned into the CXCR7‐shRNA, negative control (NC) and blank groups. The qRT‐PCR and Western blotting were applied to detect the mRNA and protein expressions of CXCR7, CXCR4 and MMP‐2 in HCCLM3 cells. Cell proliferation and invasion were evaluated by MTT and Transwell assays. A Buffalo rat model of HCC was established. Fifty model rats were divided into the CXCR7‐shRNA + TACE, CXCR7‐shRNA, TACE, NC and control groups. Immunohistochemistry was performed to detect the expressions of CXCR7, MMP‐2, vascular endothelial growth factor (VEGF) and intratumoral CD31‐positive vessel count in tumour tissues of mice. Compared with the blank and NC groups, the mRNA and protein expressions of CXCR7 and MMP‐2 were decreased in the CXCR7‐shRNA group. The cell proliferation and invasion rates of the CXCR7‐shRNA group were lower than the blank and NC groups. At the 4th week after TACE, tumour weight of the CXCR7‐shRNA + TACE group increased continuously. The CXCR7‐shRNA + TACE group showed longer survival time and smaller tumour sizes than other groups. Compared with other groups, the CXCR7‐shRNA + TACE and CXCR7‐shRNA groups had less number of lung metastatic nodules and lower expressions of CXCR7, MMP‐2, VEGF and CD31‐positive vessel count. CXCR7‐shRNA inhibits tumour invasion and metastasis to improve the efficacy of TACE in HCC by reducing the expressions of CXCR7, MMP‐2 and VEGF.     

Absence of arterial phenotype in mice with homozygous slc2A10 missense substitutions

Arterial tortuosity syndrome (ATS, MIM# 208050) is a rare autosomal recessive connective tissue disease, mainly characterized by widespread arterial involvement with elongation, tortuosity, and aneurysms of the large and middle-sized arteries (Callewaert et al., 2008, Hum Mutat 29:150-158). Recently, mutations were identified in the SLC2A10 gene encoding the facilitative glucose transporter GLUT10 (Coucke et al., 2006, Nat Genet 38:452-457). It was hypothesized that loss-of-function of the transporter results in upregulation of the transforming growth factor beta (TGFbeta) signaling pathway (Coucke et al., 2006, Nat Genet 38:452-457). We anticipated that a mouse model would help to gain more insight in the complex pathophysiological mechanism of human ATS. Here, we report that two mouse models, homozygous respectively for G128E and S150F missense substitutions in glut10 do not present any of the vascular, anatomical, or immunohistological abnormalities as encountered in human ATS patients. We conclude that these mouse strains do not phenocopy human ATS and cannot help the further elucidation of pathogenetic mechanisms underlying this disease.     

Discovery of novel hydroxy-thiazoles as HIF-alpha prolyl hydroxylase inhibitors: SAR, synthesis, and modeling evaluation

Inhibition of the PHD2 enzyme has been associated with increased red blood cell levels. From a screening hit, a series of novel hydroxyl-thiazoles were developed as potent PHD2 inhibitors.     

t-plasminogen activator inhibitor-1 polymorphism in idiopathic pulmonary arterial hypertension

AIM:

The aim of the present study was to identify the possible genotypic association of 3’UTR Hind III polymorphism of Plasminogen activator Inhibitor-1 (PAI-1) gene with idiopathic pulmonary arterial hypertension (IPAH).

BACKGROUND:

IPAH is a disorder with abnormally raised mean pulmonary arterial pressure and increase in the resistance to blood flow in pulmonary artery. One of the pathological features seen is development of intraluminal thrombin deposition leading to thrombosis. Plasminogen activator inhibitor-1 is an important inhibitor of the fibrinolytic system; its up-regulation may suppress fibrinolysis and result in an increased risk of thrombosis.

METHOD:

Blood samples from 54 IPAH patients and 100 healthy voluntary donors were analyzed by PCR-RFLP method for 3’UTR Hind III polymorphism.

RESULTS AND DISSCUSSION:

A significant association of Hd2 allele with the disease was observed. Raised mean level of right ventricular systolic pressure was observed in the Hd2/Hd2 genotypic patients, strengthening the role of Hd2 allele in the disease progression. Our data suggests an association of Hd2/Hd2 genotype, which may lead to the up-regulation of PAI-1 gene leading to increased levels of PAI-1, which is seen in IPAH. PAI-1 competes with plasminogen activators and hinders the normal mechanism of plasminogen activation system and leads to thrombosis and formation of plexiform lesions in the lung tissue, further strengthening its role in tissue remodeling and disease progression.     

Stimulatory Effect of Leptin on Nitric Oxide Production Is Impaired in Dietary‐Induced Obesity

Objective: We investigated the effect of leptin on nitric oxide production in lean and rats made obese by a high‐calorie diet. Research Methods and Procedures: The animals were placed in metabolic cages, and urine was collected in 2‐hour periods after leptin (1 mg/kg intraperintoneally) or vehicle administration. Blood was obtained 0.5, 1, 2, 4, or 6 hours after injection. Results: Leptin had no effect on systolic blood pressure in either lean or obese animals. Plasma concentration of NO metabolites (nitrites + nitrates, NO_x) increased in lean rats by 31.5%, 58.0%, and 27.9% at 1, 2, and 4 hours after leptin injection, respectively. In the obese group, plasma NO_x increased only at 2 hours (+36.5%). Leptin increased urinary NO_x excretion by 31.8% in the first 2‐hour period after injection in lean but not in obese rats. In lean animals, leptin elevated plasma cyclic 3′, 5′‐guanosine monophosphate (cGMP) at 1, 2, and 4 hours by 35.3%, 96.3%, and 57.3%, respectively. In the obese group, plasma cGMP was higher only at 2 and 4 hours (+44.6% and +32.1%, respectively). Urinary excretion of cGMP increased in lean animals by 67.1% in the first period and by 50.4% in the second period. In the obese group, leptin induced a 53.9% increase in urinary cGMP excretion only in the first 2‐hour period. Discussion: The stimulatory effect of leptin on NO production is impaired in dietary‐induced obesity; however, leptin does not increase blood pressure in obese animals, suggesting that other NO—independent depressor mechanisms are stimulated.     

Adiponectin ameliorates hypoxia-induced pulmonary arterial remodeling

We have demonstrated that adiponectin has anti-atherosclerotic properties. We also reported hypoadiponectinemia and nocturnal reduction in circulating adiponectin concentrations in patients of severe obstructive sleep apnea-hypopnea syndrome (OSAS). OSAS is often complicated with pulmonary hypertension. In this study, we investigated the effect of adiponectin on chronic hypoxia-induced pulmonary arterial remodeling in mice. Exposure of mice to 3-weeks sustained hypoxia (10% O₂) resulted in significant accumulation of adiponectin in pulmonary arteries. The percentage media wall thickness (%MT), representing pulmonary arterial remodeling, under hypoxic condition, was greater in adiponectin-knockout mice than wild-type mice. Overexpression of adiponectin significantly decreased hypoxia-induced pulmonary arterial wall thickening and right ventricular hypertrophy. These findings demonstrate for the first time that overexpression of adiponectin suppresses the development of hypoxic-induced pulmonary remodeling, and that adiponectin may combat a new strategy for pulmonary vascular changes that underlie pulmonary hypertension in OSAS.     

心衰患者动脉血气波浪式变化及其幅度降低的初步实验证据*

目的: 心力衰竭患者呼吸调控异常的机制众说纷纭,特别是动脉血气周期性波浪式变化信号的改变及其与心功能的关系尚缺乏直接的试验证据。本文依据心力衰竭患者动脉血气周期性波浪式变化信号的降低幅度,探讨心力衰竭导致呼吸调控异常的机制。方法: 选择5名心力衰竭患者,连续桡动脉逐搏取血,测定PaO₂,PaCO₂,pHa和SaO₂。选取2个典型呼吸周期,用于分析动脉血气的波浪式变化。比较患者相邻最高和最低值,以验证是否存在周期性波浪式信号变化。此外,将心力衰竭患者与心功能正常患者动脉血气周期性波浪式信号的变化幅度进行统计学t检验分析,比较有无差异。结果: 心力衰竭患者包括2例外科手术和3例ICU住院监护患者,4男1女,年龄(69±7)岁,身高(169±10)cm,体质量(75±19)kg,左心射血分数(LVEF)=(38±3)%。动脉血液充满肝素化细长塑化管需要17±2次心跳,即取血需要17±2次心跳,覆盖超过2个呼吸周期。心力衰竭患者PaO₂,PaCO₂,[H⁺]a和SaO₂均呈现明显的波浪式变化(P<0.05),幅度分别是(7.94±2.02)mmHg,(1.18±0.56)mmHg,(0.54±0.17)nmol/L和(0.21±0.07)%,分别是各自均值的(6.1±1.5)%,(3.2±1.5)%,(1.5±0.5)%和(0.2±0.1)%。与心功能正常患者比较,动脉血气波浪式变化幅度呈现明显降低趋势,但仅PaO₂和[H⁺]a有明显统计学差异(P<0.05)。结论: 采用连续逐搏动脉取血血气分析法证实,心力衰竭患者自主呼吸时动脉血气也有周期性波浪式变化信号,但其变化幅度较心功能正常患者明显降低。