scholarly journals Load magnitude affects patellar tendon mechanical properties but not collagen or collagen cross-linking after long-term strength training in older adults

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Christian S. Eriksen ◽  
Rene B. Svensson ◽  
Anne T. Gylling ◽  
Christian Couppé ◽  
S. Peter Magnusson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Older Adults ◽  
Strength Training ◽  
Patellar Tendon ◽  
Cross Linking ◽  
Term Strength ◽  
Collagen Cross Linking

Impact of oral contraceptive use and menstrual phases on patellar tendon morphology, biochemical composition, and biomechanical properties in female athletes

2013 ◽  
Vol 114 (8) ◽  
pp. 998-1008 ◽  
Author(s):  
Mette Hansen ◽  
Christian Couppe ◽  
Christina S. E. Hansen ◽  
Dorthe Skovgaard ◽  
Vuokko Kovanen ◽  
...  
Keyword(s):  
Patellar Tendon ◽  
Female Athletes ◽  
Maximum Voluntary Contraction ◽  
Biomechanical Properties ◽  
Cross Sectional Area ◽  
Cross Linking ◽  
Sectional Area ◽  
Cross Sectional ◽  
Collagen Cross Linking

Sex differences exist with regards to ligament and tendon injuries. Lower collagen synthesis has been observed in exercising women vs. men, and in users of oral contraceptives (OC) vs. nonusers, but it is unknown if OC will influence tendon biomechanics of women undergoing regular training. Thirty female athletes (handball players, 18–30 yr) were recruited: 15 long-term users of OC (7.0 ± 0.6 yr) and 15 nonusers (>5 yr). Synchronized values of patellar tendon elongation (obtained by ultrasonography) and tendon force were sampled during ramped isometric knee extensor maximum voluntary contraction to estimate mechanical tendon properties. Furthermore, tendon cross-sectional area and length were measured from MRI images, and tendon biopsies were obtained for analysis of tendon fibril characteristics and collagen cross-linking. Overall, no difference in tendon biomechanical properties, tendon fibril characteristics, or collagen cross-linking was observed between the OC users and nonusers, or between the different phases of the menstrual cycle. In athletes, tendon cross-sectional area in the preferred jumping leg tended to be larger than that in the contralateral leg ( P = 0.09), and a greater absolute ( P = 0.01) and normalized tendon stiffness ( P = 0.02), as well as a lower strain ( P = 0.04), were observed in the jumping leg compared with the contralateral leg. The results indicate that long-term OC use or menstrual phases does not influence structure or mechanical properties of the patellar tendon in female team handball athletes.

Long term results of accelerated corneal collagen cross-linking in pediatric keratoconus

2021 ◽  
pp. 112067212110183
Author(s):  
Yasin Cinar ◽  
Cagla Cilem Han ◽  
Alparslan Sahin ◽  
Zeba A Syed
Keyword(s):  
Visual Acuity ◽  
Corneal Thickness ◽  
University Hospital ◽  
Long Term Results ◽  
Cross Linking ◽  
Distance Visual Acuity ◽  
The Mean ◽  
Collagen Cross Linking ◽  
Corneal Collagen

Purpose: To evaluate the long term visual, refractive, and corneal tomographic outcomes of epithelium-off accelerated corneal collagen cross-linking (ACXL) in the management of pediatric keratoconus (KC). Methods: This retrospective study included patients under 18 years old with progressive KC who underwent ACXL between 2012 and 2019 at Dicle University Hospital. Complete ophthalmic examination was performed including uncorrected distance visual acuity (UDVA), best spectacle-corrected distance visual acuity (CDVA), manifest refraction, and corneal tomography. Evaluations were performed preoperatively and at 6 months intervals postoperatively. Results: Forty-nine eyes of 49 patients were included in the study. The mean age of patients at the time of ACXL was 14.2 ± 1.8 (range: 9.5–17.3) years. Mean follow up was 4.61 ± 1.90 (range: 2.0–8.1) years. The mean LogMAR UDVA improved from 0.94 ± 0.41 to 0.81 ± 0.43, 0.69 ± 0.41, and 0.67 ± 0.33 after 1, 3, and 5 years respectively ( p = 0.001). The mean LogMAR CDVA improved from 0.58 ± 0.36 to 0.46 ± 0.31, 0.34 ± 0.23, and 0.39 ± 0.27 after 1, 3, and 5 years respectively ( p = 0.015). The mean refractive cylinder improved significantly from 6.01 ± 2.07 diopters (D) to 5.46 ± 1.87, 5.38 ± 2.18, and 5.02 ± 2.31 D after 1, 3, and 5 years respectively ( p = 0.005). As compared to preoperative values, steep keratometry and maximum keratometry were not significantly different ( p = 0.805 and 0.448, respectively) following ACXL, while flat keratometry significantly improved after ACXL ( p = 0.012). Although central corneal thicknesses decreased significantly ( p = 0.029), the decrease in thinnest corneal thickness was not statistically significant ( p = 0.205). Conclusion: Epithelium-off ACXL seems to be effective for halting KC progression with long term clinical benefits in pediatric patients.

scholarly journals Determinants of mechanical properties in the developing ovine thoracic aorta

1999 ◽  
Vol 277 (4) ◽  
pp. H1385-H1391 ◽  
Author(s):  
Sarah M. Wells ◽  
B. Lowell Langille ◽  
J. Michael Lee ◽  
S. Lee Adamson
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Tensile Stress ◽  
Thoracic Aorta ◽  
Adult Life ◽  
Perinatal Period ◽  
Developmental Changes ◽  
Cross Linking ◽  
Postnatal Life ◽  
Collagen Cross Linking

We previously reported changes in mechanical properties and collagen cross-linking of the ovine thoracic aorta during perinatal development and postnatal maturation, and we now report changes in biochemical composition (elastin, collagen, and DNA contents per mg wet wt) over the same developmental intervals. A comparison of results from the present and previous studies has yielded novel and important observations concerning the relationship between aortic mechanics and composition during maturation. Developmental changes in aortic incremental elastic modulus at low tensile stress ( E low) closely followed changes in relative elastin content (i.e., per mg wet wt). An 89% increase in E low during the perinatal period was associated with a 69% increase in relative elastin content, whereas neither variable changed during postnatal life. Incremental elastic modulus at high tensile stress ( E high) did not change during the perinatal period but increased 88% during postnatal life. This pattern closely paralleled changes in collagen cross-linking index, which did not change perinatally but almost doubled postnatally. In contrast, relative collagen content (per mg wet wt) increased only slightly from fetal to adult life, a trend that was unrelated to aortic mechanics. Substantial, progressive decreases in measures of wall viscosity (pressure wave attenuation coefficient and viscoelastic phase angle) from fetal to adult life followed the pattern observed for relative DNA (smooth muscle cell) content (per mg wet wt). Our findings suggest that accumulation of elastin per milligram wet weight contributes most to developmental changes in E low, change in collagen cross-linking is the primary determinant of developmental changes in E high, and cell accumulation contributes most to developmental changes in wall viscosity.

scholarly journals Long-term Follow-up of Pachymetric and Topographic Alterations after Corneal Collagen Cross-Linking for Keratoconus

2012 ◽  
Vol 1 (1) ◽  
pp. 22-25
Author(s):  
Paraskevi G Zotta ◽  
Diamantis D Almaliotis ◽  
George D Kymionis ◽  
Vasilios F Diakonis ◽  
Kostas A Moschou ◽  
...  
Keyword(s):  
Corneal Thickness ◽  
Case Series ◽  
Cross Linking ◽  
Retrospective Case ◽  
Time Intervals ◽  
Long Term Follow Up ◽  
Collagen Cross Linking ◽  
Corneal Collagen

ABSTRACT Purpose To determine the long-term alterations of corneal thickness, along with topographic outcomes, after corneal collagen cross-linking treatment (CXL) for keratoconus. Materials and methods In this retrospective case series, 46 patients (52 eyes), 32 males and 14 females, with progressive keratoconus were included. All eyes underwent CXL in accordance with the standard protocol (Dresden) for the treatment of their ectatic corneal disorder between January 2006 and June 2007. Pachymetric and topographic outcomes were evaluated preoperatively and at 1, 3, 6, 12, 24 and 36 months postoperatively. Results Mean follow-up was 28.08 ± 8.39 months (range, from 12 to 36 months). A statistically significant decline in corneal pachymetric values (at the thinnest location) when compared with preoperative values (467.65 ± 41.08 µm) was demonstrated at 1 (437.63 ± 50.57 µm), 3 (439.08 ± 52.27 µm), 6 (449.37 ± 52.73 µm), 12 (449.63 ± 83.53 µm) and 24 (459.97 ± 47.32 µm) months after CXL (p < 0.05, for all mentioned time intervals). Return to preoperative pachymetric values (469.52 ± 40.52 µm) was revealed 36 months post-CXL (p > 0.05). With respect to topographic (flat and steep keratometric values, keratoconus index), no statistically significant differences between preoperative and all postoperative intervals were found (p > 0.05, for all values for all time intervals). Conclusion Corneal pachymetric values reduce significantly up to 24 months after CXL treatment, while a return to preoperative values was revealed 36 months after the procedure. No significant changes’ concerning topographic outcomes was demonstrated after CXL, indicating stability of these parameters. How to cite this article Zotta PG, Almaliotis DD, Kymionis GD, Diakonis VF, Moschou KA, Karampatakis VE. Long-term Follow-up of Pachymetric and Topographic Alterations after Corneal Collagen Cross-Linking for Keratoconus. Int J Keratoco Ectatic Corneal Dis 2012;1(1):22-25.

PROSPECTS FOR THE USE OF HOT ISOSTATIC PRESSING IN CAST ALUMINUM ALLOYS (review)

2021 ◽  
pp. 17-26
Author(s):  
E.A. Prokhorchuk ◽  
◽  
K.A. Vlasova ◽  
A.V. Trapeznikov ◽  
Yu.V. Reshetnikov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloys ◽  
Hot Isostatic Pressing ◽  
Term Strength ◽  
Cast Aluminum ◽  
Dense Structure ◽  
Isostatic Pressing ◽  
Cast Aluminum Alloys ◽  
Strength Tests

The article provides an overview of studies on the influence of HIP on the density, roughness and mechanical properties of cast aluminum alloys. As a result of HIP, the density of the alloy, its ductility, and cyclic characteristics increase, and the scatter of mechanical properties determined during tensile and long-term strength tests decreases. The use of HIP increases the yield of good casting due to the reduction of rejects due to unacceptable porosity detected during х-ray inspection. Thus, the casting acquires a homogeneous, completely dense structure.

Sign in / Sign up

Export Citation Format

Share Document