The mechanical and morphological properties of systemic and pulmonary arteries differ in the Madagascar ground boa, a snake without ventricular pressure separation.

The walls of the mammalian aorta and pulmonary artery are characterized by diverging morphologies and mechanical properties, which have been correlated with high systemic and low pulmonary blood pressure, as a result of intraventricular pressure separation. However, the relationship between intraventricular pressure separation and diverging aortic and pulmonary artery wall morphologies and mechanical characteristics is not understood. The snake cardiovascular system poses a unique model for the study of this relationship, as representatives both with and without intraventricular pressure separation exist.

Endothelial Dysfunction and Passive Changes in the Aorta and Coronary Arteries of Diabetic db/db Mice.

Endothelial cell dysfunction and vessel stiffening are associated with a worsened prognosis in diabetic patients with cardiovascular diseases. The present study hypothesized that sex impacts endothelial dysfunction and structural changes in arteries from diabetic mice. In diabetic (db/db) and normoglycaemic (db/db+) mice, the mechanical properties were investigated in pressurized isolated left anterior descending coronary arteries and aorta segments that were subjected to tensile testing.

Analysis of vascular mechanical properties of the yellow anaconda reveals increased elasticity and distensibility of the pulmonary artery during digestion.

In animals with functional division of blood systemic and pulmonary pressures, such as mammals, birds, crocodilians and a few non-crocodilian reptiles, the vessel walls of systemic and pulmonary arteries are exquisitely adapted to endure different pressures during the cardiac cycle, systemic arteries being stronger and stiffer than pulmonary arteries. However, the typical non-crocodilian reptile heart possesses an undivided ventricle that provides similar systolic blood pressure to both circuits. This raises the question whether in these species the systemic and pulmonary mechanical vascular properties are similar.

Impact of chronic hypoxia on proximal pulmonary artery wave propagation and mechanical properties in rats.

Arterial stiffness and wave reflection are important components of the ventricular afterload. Therefore, we aimed to assess the arterial wave characteristics and mechanical properties of the proximal pulmonary arteries (PAs) in the hypoxic pulmonary hypertensive rat model. After 21 days in normoxic or hypoxic chambers (24 animals/group), animals underwent transthoracic echocardiography and PA catheterization with a dual-tipped pressure and Doppler flow sensor wire.

Mid-term function and remodeling potential of tissue engineered tricuspid valve: Histology and biomechanics.

Objective: Tricuspid valve reconstruction using a small intestinal submucosal porcine extracellular matrix (ECM) tube graft is hypothesized to be durable for six months and show signs of recellularization and growth potential. The purpose was to histologically and biomechanically test ECM valves before and after six months of implantation in pigs for comparison with native valves.

Methods: Ten 60 kg pigs were included, which survived tricuspid valve tube graft insertion.

How Heart Valves Evolve to Adapt to an Extreme-Pressure System: Morphologic and Biomechanical Properties of Giraffe Heart Valves.

Background: Heart valves which exist naturally in an extreme-pressure system must have evolved in a way to resist the stresses of high pressure. Giraffes are interesting as they naturally have a blood pressure twice that of humans. Thus, knowledge regarding giraffe heart valves may aid in developing techniques to design improved pressure-resistant biological heart valves.

Electrospun biodegradable microfibers induce new collagen formation in a rat abdominal wall defect model: A possible treatment for pelvic floor repair?

Half of the female population over age 50 years will experience pelvic organ prolapse. We suggest a new approach based on tissue engineering principles to functionally reconstruct the anatomical structures of the pelvic floor. The aim of this study is to investigate the mechanical performance and effect on collagen and elastin production of a degradable mesh releasing basic fibroblast growth factor (bFGF).

The mechanical properties of the systemic and pulmonary arteries of Python regius correlate with blood pressures.

Pythons are unique amongst snakes in having different pressures in the aortas and pulmonary arteries because of intraventricular pressure separation. In this study, we investigate whether this correlates with different blood vessel strength in the ball python Python regius. We excised segments from the left, right, and dorsal aortas, and from the two pulmonary arteries.

Mechanisms involved in extracellular matrix remodeling and arterial stiffness induced by hyaluronan accumulation.

Background And Aims: Hyperglycemia induces hyaluronan (HA) accumulation in the vasculature. Excessive accumulation of HA around the vascular smooth muscle cells (VSMC) results in increased aortic stiffness and strength and accelerated atherosclerosis in ApoE(-)/(-) mice. We hypothesized that HA accumulation primes the vasculature for atherosclerosis by crosslinking and reorganizing the extracellular matrix (ECM) and by pushing VSMC differentiation towards a less mature phenotype.

Topography-Guided Proliferation: Distinct Surface Microtopography Increases Proliferation of Chondrocytes In Vitro.

Chondrocyte-based cartilage repair techniques require control of articular chondrocyte expansion ex vivo. Articular chondrocytes have limited availability, and prolonged culturing to obtain a cell number sufficient for clinical use often results in phenotypic alterations and increased costs. In this study, we applied a screening library consisting of micrometer-sized topographical features, termed biosurface structure array (BSSA), to identify specific topographical microstructures affecting the proliferation of human chondrocytes in passage 1 (P1) or 2 (P2).

Differential effects of Smad3 targeting in a murine model of chronic kidney disease.

Transforming growth factor (TGF)-β1 has a pivotal role in the pathogenesis of progressive kidney diseases that are characterized by fibrosis. The main intracellular signaling pathway of TGF-β1 is the Smad system, where Smad2 and Smad3 play a central role in transcriptional regulation of target genes involved in extracellular matrix (ECM) metabolism. This study analyzes the hypothesis that blockade of Smad3 attenuates the development of TGF-β1-driven renal fibrosis.

Three-dimensional microarchitecture of adolescent cancellous bone.

This study investigated microarchitectural, mechanical, collagen and mineral properties of normal adolescent cancellous bone, and compared them with adult and aging cancellous bone, to obtain more insight into the subchondral bone adaptations during development and growth. Twenty-three human proximal tibiae were harvested and divided into 3 groups according to their ages: adolescence (9 to 17 years, n=6), young adult (18 to 24 years, n=9), and adult (25 to 30 years, n=8). Twelve cubic cancellous bone samples with dimensions of 8×8×8 mm(3) were produced from each tibia, 6 from each medial and lateral condyle.

The effects of glucocorticoid on microarchitecture, collagen, mineral and mechanical properties of sheep femur cortical bone.

In this study, 18 female skeletally mature sheep were randomly allocated into three groups of six each. Group 1 (glucocorticoid-1) received prednisolone treatment (0.60 mg/kg/day, five times weekly) for 7 months.

A biomechanical, histological and biochemical study in an experimental rabbit hypospadias repair model using scanning acoustic microscopy.

Objective: To investigate the biomechanical, histological and biochemical properties of rabbit urethra at long-term follow up after hypospadias simulation and acute repair.

Materials And Methods: Thirty-eight white New Zealand male rabbits underwent experimental creation of a hypospadias-like defect and acute repair (mobilization and advancement, tubularized incised posterior urethral plate (TIP), modified TIP) and sham operation. After 23 weeks all groups + controls underwent biomechanical, histological and biochemical assessments.

Cervical collagen and biomechanical strength in non-pregnant women with a history of cervical insufficiency.

Background: It has been suggested that cervical insufficiency (CI) is characterized by a "muscular cervix" with low collagen and high smooth muscle concentrations also in the non-pregnant state. Therefore, the aim of this study was to investigate the biomechanical properties, collagen concentration, smooth muscle cell density, and collagen fiber orientation in cervical biopsies from non-pregnant women with a history of CI.

Methods: Cervical punch biopsies (2 x 15 mm) were obtained from 57 normal non-pregnant women and 22 women with a history of CI.

Collagen concentration and biomechanical properties of samples from the lower uterine cervix in relation to age and parity in non-pregnant women.

Background: During normal pregnancy the cervix has a load bearing function. The cervical tissue consists mainly of an extracellular matrix (ECM) rich in collagen; important for the biomechanical properties. The aim of the present study was to evaluate how the biomechanical strength of samples from the distal cervix is associated with collagen content in relation to age and parity.

Balance between matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) in the cervical mucus plug estimated by determination of free non-complexed TIMP.

Background: The cervical mucus plug (CMP) is a semi-solid structure with antibacterial properties positioned in the cervical canal during pregnancy. The CMP contains high concentrations of matrix metalloproteinase 8 and 9 (MMP-8, MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1). This indicates a potential to degrade extracellular matrix components depending on the balance between free non-complexed inhibitors and active enzymes.

The effects of bone remodeling inhibition by alendronate on three-dimensional microarchitecture of subchondral bone tissues in guinea pig primary osteoarthrosis.

We assessed whether increase of subchondral bone density enhances cartilage stress during impact loading, leading to progressive cartilage degeneration and accelerated osteoarthrosis (OA) progression. Sixty-six male guinea pigs were randomly divided into six groups. During a 9-week treatment period, four groups received twice-weekly subcutaneous injections of alendronate (ALN) in two doses: two groups received 10 microg/kg and two groups received 50 microg/kg.

Biomechanical and biochemical assessment of properties of the anterior urethra after hypospadias repair in a rabbit model.

Purpose: We created a rabbit model to test hypospadias operations and investigate the biomechanical properties of the urethra at long-term followup using biomechanical and biochemical assessments.

Materials And Methods: A total of 38 New Zealand White rabbits were randomized into 4 groups, including controls, sham operation and 2 operation groups (experimental creation of a hypospadias-like defect and acute repair, respectively). In operation group 1 the ventral urethral wall and dorsal plate were longitudinally incised, half of the ventral urethral wall was excised (hypospadias-like defect) and the incised urethra was tubularized (tubularized incised posterior plate urethroplasty group).

Biglycan deficiency causes spontaneous aortic dissection and rupture in mice.

Background: For the majority of cases, the cause of spontaneous aortic dissection and rupture is unknown. An inherited risk is associated with Marfan syndrome, Ehlers-Danlos syndrome type IV, and loci mapped to diverse autosomal chromosomes. Analysis of pedigrees however has indicated that it may be also inherited as an X-linked trait.

MMP-2 in the left rat ventricle is increased by growth hormone.

In cardiac hypertrophy induced by GH, the turn-over of collagen seems to be increased. Matrix metalloproteinases (MMP) are enzymes suggested to contribute to the remodelling of the extracellular matrix in the myocardium. The aim of the present experiment was to investigate how GH influenced MMP concentration, collagen concentration, and structure of the connective tissue of the LV in young rats in relation to time.

Plasminogen activator inhibitor-1 gene deficiency attenuates TGF-beta1-induced kidney disease.

Background: Transforming growth factor-beta1 (TGF-beta1) stimulates the deposition of extracellular matrix (ECM), which is a hallmark in end-stage renal disease. The importance of TGF-beta1-induced changes in protease activity in this process is not fully elucidated. TGF-beta1 up-regulates plasminogen activator inhibitor type 1 (PAI-1), which lowers matrix degradation.

Effects of hyaluronan on three-dimensional microarchitecture of subchondral bone tissues in guinea pig primary osteoarthrosis.

Hyaluronan (HA) has received increasing interest as a potential agent in therapeutic intervention in osteoarthrosis (OA). HA has been shown to reduce arthritic lesions in experimental animal models of articular cartilage injury. This study was to investigate the effects of high molecular weight HA intra-articular injection on subchondral bone tissues.

Matrix metalloproteinases and their inhibitors in the cervical mucus plug at term of pregnancy.

Objective: This study was undertaken to evaluate the presence of matrix metalloproteinases (MMPs) and their inhibitors in the cervical mucus plug obtained during active labor at term.

Study Design: Cervical mucus plugs from 17 healthy women in normal active labor were homogenized, extracted, and analyzed by 4 different assays.

Results: Gelatin zymography revealed large amounts of MMP-2 and MMP-9, and triple-helical collagen degradation demonstrated collagenase activity (MMP-8).

Tensile mechanical and creep properties of Descemet's membrane and lens capsule.

Descemet's membrane (DM) and the lens capsule (LC) are two ocular basement membrane structures which in comparison with other basement membranes have exceptional thicknesses which increase with age. Both membranes are supposed to contain networks of type IV collagen and laminin linked together with nidogen/entactin and containing other glycoproteins and proteoglycans. DM is a unique basement membrane which in addition contains fine filaments of type VIII collagen arranged in a hexagonal lattice.