Thickness Of Elastic Lamina Research Articles

Zonular defects in loxl1-deficient zebrafish.

To investigate the roles of the lysyl oxidase-like 1 (loxl1) gene in zebrafish eye development and the potency of loxl1 deficiency in mimicking the ocular manifestations of exfoliation syndrome (XFS). CRISPR/Cas9 technology was used to generate a frameshift coding deletion in zebrafish loxl1. Expression profiles and ocular manifestations of the wildtype, heterozygous mutant (loxl1+/- ) and homozygous mutant (loxl1-/- ) zebrafish were analysed in a range of developmental stages from zebrafish larvae to dissected adult zebrafish eyes. The loxl1 deficiency caused zonular bundling disorders in juvenile zebrafish and accumulation of pearl-like particles adhering to the adult zebrafish zonule. The bundles appeared to lack form and were thinner in both loxl1+/- and loxl1-/- zebrafish compared with the wildtype (p < 0.01 for all Bonferroni post-hoc analyses). The zonule of loxl1-/- zebrafish appeared stretched, ragged and torn, with isolated fibres also detected. The particles in loxl1-/- zebrafish were more numerous (counts: 92.33 ± 10.02/100 μm2 vs. 58.33 ± 5.03/100 μm2 , p=0.006), but smaller in size (diameter: 0.21 ± 0.03 μm vs. 0.43 ± 0.04 μm, p=0.002) compared with those in loxl1+/- . Transmission electron microscopy revealed thinning or even loss of elastic lamina in loxl1+/- Bruch's membrane (BM) (thickness of elastic lamina: 92.94 ± 18.19 nm in the wildtype vs 35.65 ± 14.76 nm in loxl1+/- , p=0.003). The breakage of BM was observed in loxl1-/- . The loxl1-/- zebrafish is a promising animal model of XFS zonular pathology.

ROSTAFUROXIN AMELIORATES THE INWARD REMODELING AND STIFFNESS IN RESISTANCE ARTERIES FROM DEOXYCORTICOSTERONE ACETATE-SALT HYPERTENSIVE RATS

Objective: We have shown that rostafuroxin (ROSTA), an antagonist of endogenous ouabain (OUA), block the biding of OUA to Na+ K+ -ATPase and inhibits the cSRC downstream activation in mesenteric resistance arteries (MRA), which ameliorates endothelial dysfunction and oxidative stress, as reduces hypertension in deoxycorticosterone acetate (DOCA)-salt rats. In addition, MRA of DOCA-salt rats also present the hypertrophic inward remodeling with stiffness. Moreover, the chronic treatment with OUA induces hypotrophic inward remodeling with stiffness in MRA. In line with these results we investigate the role of endogenous OUA on remodeling and stiffness in MRA of DOCA-salt rats. Design and method: A hypertensive model was established in uninephrectomized Wistar rats using DOCA-salt. After 5 weeks DOCA-salt treatment, with high systolic blood pressure (SBP) stabilization, this hypertensive model was divided into two groups: DOCA-salt and DOCA-salt co-treated with ROSTA (1 mg/kg per day gavage, 3 weeks). The SBP was measured using the tail-cuff method, and vascular remodeling was assessed in MRA using a pressure myograph. Histological and western blot analysis were performed in MRA. Results: Our results reinforce that ROSTA treatment reduces SBP in DOCA-salt rats, but did not restore it to control levels. For the first time, the results suggest that ROSTA ameliorates the remodeling and stiffness observed in MRA of DOCA-salt rats, enhancing the luminal diameter and distensibility, reducing the cross-section area and wall/lumen ratio as well as shifting to the right the stress-strain curve in MRA. ROSTA restores collagen type I/III ratio, internal elastic lamina thickness, tyrosine kinase Src phosphorylation (Tyr418), as well EGFR, cRaf, ERK, p38MAPK, TGFβ1, CTGF, and collagen I protein expression in MRA from DOCA-salt rats. Conclusions: The results suggested that ROSTA reduces hypertension, the hypertrophic inward remodeling and the augmented wall/lumen ratio in MRA of DOCA-salt rats. In addition, endogenous OUA emerges as an important mechanism to induce vascular stiffness via Na+ K+ -ATPase/ cSRC/ EGFR/ cRas/ ERK/ p38MAPK/ CTGF/ TGFβ1 pathway in MRA. These results reinforce the idea that endogenous OUA is a putative target for the treatment of vascular adjustments present in hypertension.

Influence of elastin on rat small artery mechanical properties

We have previously developed a method for estimating elastin content and organization in resistance arteries, where it is a minor component. The aim of the present study was to validate the method against a quantitative assay and to determine the relative importance of elastin content and organization for intrinsic elasticity of small arteries. Mesenteric third order branches (from 10-day-old, 1- and 6-month-old rats) and middle cerebral arteries (from 6-month-old rats) were pressurized. beta-Values were calculated from stress-strain relationships and used as indicators of intrinsic stiffness. The same pressure-fixed arteries were used to estimate elastin content and organization in the internal elastic lamina with confocal microscopy. Collagen and elastin contents were determined by Picrosirius Red staining and radioimmunoassay for desmosine, respectively. Confocal and desmosine assays gave similar results: no difference in elastin content of mesenteric vessels from 1- and 6-month-old rats, and a significant reduction in cerebral compared to mesenteric arteries. For all parameters (elastin and collagen content, fenestrae area and internal elastic lamina thickness) the best correlation was found between beta-values and fenestrae size. These data suggest that in small arteries: (1) confocal microscopy can be used as a method for the simultaneous study of changes in elastin content and organization; and (2) elastin organization might be a key determinant of intrinsic elastic properties.

Ultrastructural changes in omental resistance artery in women with preeclampsia

Objective: The reduced function that is played by the endothelium has been suggested in the pathophysiologic condition of resistance arteries during preeclampsia. Our aim was to determine whether morphologic changes occur in these arteries in patients with preeclampsia. Study Design: The omental resistance arteries were isolated from 11 women with preeclampsia and 10 normotensive pregnant women; the preparations were analyzed by light and electron microscopy. Results: On light microscopic examination, no differences were apparent between both groups of women in cross-sectional preparations of the omental resistance arteries. However, after electron microscopic examination, characteristic changes were found in the subendothelial region of the resistance arteries from women with preeclampsia compared with specimens from normotensive pregnant women. The thickness of elastic lamina was irregular, and the basement membrane was, in part, incomplete. Thus, the arrangement of the location of endothelial cells was changed in the resistance arteries that were taken from women with preeclampsia. Conclusion: These results indicate that ultrastructural changes develop in the subendothelial region of omental resistance arteries in women with preeclampsia. (Am J Obstet Gynecol 2003;189:216-21.)

Morphology of the Internal Elastic Lamina in Arteries from Pulmonary Hypertensive Patients: a Confocal Laser Microscopy Study

The development and progression of pulmonary hypertension lesions involve continuous remodeling of the arterial wall, including the extracellular matrix components. The integrity of the internal elastic lamina may represent a barrier to cell migration and formation of intimal proliferative lesions. Some patients with congenital cardiac shunts develop precocious intimal occlusive lesions,whereas others evolve with isolated medial hypertrophy. We studied the 2-D and 3-D morphology of the internal elastic lamina of peripheral pulmonary arteries to search for any difference regarding the type of histological lesion. Fifteen lung biopsies collected for diagnostic purposes from patients with congenital shunts and 6 control lungs (mean ages, 15.8 and 14.7 mo) were studied using the confocal laser scanning microscope, under predetermined conditions of laser intensity, brightness and contrast. We measured the thickness of the internal elastic lamina and determined the number of gaps and projections of elastic tissue towards the medial and intimal layers. The mean internal elastic lamina thickness was significantly higher in arteries from cases with isolated medial hypertrophy when compared with controls and to those with proliferative lesions (P < .05). The number of gaps of the internal elastic lamina was higher in arteries >100 μm in diameter from the group with intimal lesions when compared to the cases presenting with isolated hypertrophy, but did not differ from the controls. There was a positive linear correlation between the external arterial diameter and the thickness of the internal elastic lamina (r = .74, P < .001) in cases presenting isolated medial hypertrophy. The increased thickness and smaller number of gaps of the internal elastic lamina may act as a barrier that prevents smooth muscle cell migration in patients with pulmonary hypertension without intimal proliferative lesions. On the other hand, a greater number of gaps does not represent, by itself, unrestrained migration, because controls also showed fenestrated laminae.