Ovariectomy with simulated vaginal delivery to establish a rat model for pelvic organ prolapse

The widespread prevalence of Pelvic Organ Prolapse (POP) and the paucity of ongoing treatments prompted us to develop a unique rat model combining ovariectomy and simulated vaginal delivery. We hypothesized that the tissue changes caused by low hormone levels and mechanical stretch could complement each other. Thus, the combined model can potentially mimic the collagen metabolism of vaginal wall tissue as well as mechanical stretch properties to complement disease progression in POP. Ovariectomy with sequential simulated vaginal delivery was performed on rats in the modeling group. Sham surgeries were performed as control. At 2, 4, and 12 weeks after modeling, the vaginal tissues of rats were evaluated by Masson's trichrome staining, Picro-Sirius red staining, immunohistochemistry, western blotting, and uniaxial tensile tests. Compared to the control group, the vaginal tissues of the model rats showed an atrophic epithelial layer and loose collagen fibers. The smooth muscle fibers were ruptured, smaller in diameter, and disorganized. The ratio of collagen type I/III significantly increased, but the contents of both Collagen I and III decreased. The expression of metalloproteinases 2 and 9 in the tissues increased, and the expression of tissue inhibitors of metalloproteinases 1 and 2 decreased. The tangent modulus of the tissues was significantly increased in the model rats. We verified a novel method to establish a pelvic organ prolapse model in rats. This approach combined the advantages of low hormone levels and mechanical stretch effects.

Effects of osteogenic growth peptide C-terminal pentapeptide and its analogue on bone remodeling in an osteoporosis rat model

This study aimed to explore the effects of osteogenic growth peptide C-terminal pentapeptide (G36G), and its analog G48A on bone modeling in rats with ovariectomy-induced osteoporosis. Ovariectomized rats were administered PBS (OVX group), risedronate (RISE group), G36G combined with risedronate (36GRI group), G36G (G36G group), or G48A (G48A group). The sham-operation rats (SHAM group) were administered PBS. Serum osteocalcin and IGF-2 levels in the SHAM, OVX, G36G, G48A, and RISE groups were observably lower than the 36GRI group (P < 0.01) and the bone mineral density of the entire femur, distal metaphysis, and lumbar L1-L4 in the 36GRI group were notably increased (P < 0.05). The bending energy of the 36GRI group was prominently higher than the other groups (P < 0.05). Other features measured in the study that provided significant outcomes was the ratio of femora ash weight/dry weigh, parameters of trabecular bone volume (TBV)/total tissue volume, TBV/sponge bone volume, mean trabecular plate thickness, mean trabecular plate space, bone surface, parameters of sfract(s) and sfract(d), tetracycline-labeled, and osteoid surfaces. Bone loss in ovariectomized rats may be partially inhibited by G36G and G48A. A combination treatment with G36G and risedronate may be an effective intervention for osteoporosis.

Change in the corneal material mechanical property for small incision lenticule extraction surgery

Purpose: To assess the distribution characteristics and related factors of stress-strain index (SSI) values and discuss changes in biomechanical parameters, including SSI, after small incision lenticule extraction (SMILE) surgery. Methods: This study included 253 patients who underwent SMILE (253 eyes). SSI and other biomechanical parameters were measured using corneal visualization Scheimpflug technology before and 3 months after surgery. The data collected included SSI, central corneal thickness (CCT), and eight other dynamic corneal response parameters. The Kolmogorov-Smirnov test, Pearson and partial correlation analyses, and paired-sample t-tests were used for statistical analyses. Results: Both pre-op SSI and ΔSSI follow a normal distribution, while post-op SSI does not follow a normal distribution. The decline in SSI after SMILE surgery was not statistically significant, and the data dispersion of SSI after SMILE surgery was close to that before surgery (p > 0.05). No statistical correlation was noted between SSI values and age and pre-op CCT (all p > 0.05). However, both pre- and post-op SSI values decreased with increasing degree of myopia (all p < 0.05), and weakly correlated with preoperative intraocular pressure and biomechanically corrected intraocular pressure (all p < 0.05). Other biomechanical parameters changed significantly after surgery (all p < 0.001). After SMILE, the magnitude of the deformation at the highest concave, deformation ratio, and integral radius increased significantly (all p < 0.001), while the Ambrosio relational thickness horizontal, stiffness parameter A1, and Corvis biomechanical index decreased significantly (p < 0.001). Conclusion: SSI, which reflects essential corneal material attributes, differs from other corneal biomechanical parameters and remains stable before and after SMILE surgery, and can be used as an indicator to evaluate changes in corneal material properties after SMILE surgery.

A Modified Flexor Tendon Suture Technique Combining Kessler and Loop Lock Flexor Tendon Sutures

OBJECTIVES

In the present study, a novel single knot tenorrhaphy was developed by combining the modified Kessler flexor tendon suture (MK) with the loop lock technique.

METHODS

A total of 48 porcine flexor digitorum profundus tendons were collected and randomly divided into six groups. The tendons were transversely cut and then repaired using six different techniques, the MK method, double knot Kessler-loop lock flexor tendon suture (DK), and single knot Kessler-loop lock flexor tendon suture (SK), each in combination with the epitendinous suture (P), and the same three techniques without P. Furthermore, by performing the load-to-failure tests, the biomechanical properties and the time taken to complete a repair, for each tenorrhaphy, were assessed.

RESULTS

Compared to the MK+P method, DK+P was more improved, thereby enhancing the ultimate tensile strength. The SK+P method, which required fewer knots than DK+P, was easier to perform. Moreover, the SK+P repair increased the force at a 2-mm gap formation, while requiring lesser knots than DK+P.

CONCLUSION

As opposed to the traditional MK+P method, the SK+P method was improved and exhibited better biomechanical properties, which may facilitate early mobilization after the repair.

The effect of tail suspension and treadmill exercise on LRP6 expression, bone mass and biomechanical properties of hindlimb bones in SD rats

Purpose: To investigate whether mechanical load regulates LRP6 expression and whether different intensities of treadmill exercise have different effects on LRP6 expression and the biomechanical properties of hindlimb bones in Sprague-Dawley (SD) rats. Methods: Fifty-six three-month-old virgin female SD rats were randomly divided into seven groups (n=8). Each group was subjected to tail suspension, free physiological activity or different intensities of treadmill exercise according to the experimental design for four or eight weeks. Rats were sacrificed after the intervention based on experimental design, and fresh femurs, tibias and fibulas were harvested for molecular biological analysis, biomechanical testing and micro-CT analysis. Results: LRP6 expression and the Wnt/β-catenin pathway activity decreased, and bone mass and biomechanical properties decreased after loss of mechanical stimulation. For disuse osteoporosis, even physiological activity could improve LRP6 expression, Wnt/β-catenin pathway activity, bone mass and biomechanical properties. Compared with physiological activity, treadmill exercise had better and faster effects on bone recovery. Compared with the Low intensity Exercise Group (LE group), the Medium intensity Exercise Group (ME group) and High intensity Exercise Group (HE group) had higher LRP6 expression, bone mass and biomechanical properties, while there were no significant difference between the ME group and HE group. Conclusions: Mechanical load appears to be a regulator of LRP6 expression, and it further affects the Wnt/β-catenin pathway activity and bone mass. The LRP6 expression, bone mass and biomechanical properties gradually improve as treadmill exercise intensity increases, while there is no significant difference between the ME group and HE group.

Repeatability of the Novel Intraocular Pressure Measurement From Corvis ST

Purpose

To assess the repeatability of intraocular pressure (IOP) measured with the Corvis ST (CST) and the Ocular Response Analyzer (ORA).

Methods

A total of 141 eyes from 141 subjects were studied, including 35 healthy eyes and 106 glaucomatous eyes. All subjects underwent IOP evaluations with Goldmann applanation tonometer, CST, and ORA. With CST, biomechanical corrected IOP (bIOP) was calculated; bIOP is purported to be less dependent on biomechanical properties. For ORA, corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated IOP (IOPg) were derived. The repeatability of the various IOP values was assessed using the coefficient of variance (CV) and the intraclass correlation coefficient (ICC).

Results

The CV with bIOP (5.5 ± 3.1: mean ± standard deviation) was significantly smaller than the CVs measured with IOPg (7.3 ± 4.3) and IOPcc (7.2 ± 4.4). ICC values were 0.90, 0.80, and 0.86 with IOPg, IOPcc, and bIOP, respectively.

Conclusions

The bIOP showed a better prevision and repeatability for IOP measurement.

Translational Relevance

The bIOP measurement from CST had a better reproducible than IOPcc measurement from ORA.

Enlarged Optic Nerve Axons and Reduced Visual Function in Mice with Defective Microfibrils

Glaucoma is a leading cause of irreversible vision loss due to retinal ganglion cell (RGC) degeneration that develops slowly with age. Elevated intraocular pressure (IOP) is a significant risk factor, although many patients develop glaucoma with IOP in the normal range. Mutations in microfibril-associated genes cause glaucoma in animal models, suggesting the hypothesis that microfibril defects contribute to glaucoma. To test this hypothesis, we investigated IOP and functional/structural correlates of RGC degeneration in mice of either sex with abnormal microfibrils due to heterozygous Tsk mutation of the fibrilin-1 gene (Fbn1^Tsk/+). Although IOP was not affected, Fbn1^Tsk/+ mice developed functional deficits at advanced age consistent with glaucoma, including reduced RGC responses in electroretinogram (ERG) experiments. While RGC density in the retina was not affected, the density of RGC axons in the optic nerve was significantly reduced in Fbn1^Tsk/+ mice. However, reduced axon density correlated with expanded optic nerves, resulting in similar numbers of axons in Fbn1^Tsk/+ and control nerves. Axons in the optic nerves of Fbn1^Tsk/+ mice were significantly enlarged and axon diameter was strongly correlated with optic nerve area, as has been reported in early pathogenesis of the DBA/2J mouse model of glaucoma. Our results suggest that microfibril abnormalities can lead to phenotypes found in early-stage glaucomatous neurodegeneration. Thinning of the elastic fiber-rich pia mater was found in Fbn1^Tsk/+ mice, suggesting mechanisms allowing for optic nerve expansion and a possible biomechanical contribution to determination of axon caliber.

Changes in the biomechanical properties of a single cell induced by nonthermal atmospheric pressure micro-dielectric barrier discharge plasma

Mechanical properties of a single cell are closely related to the fate and functions of the cell. Changes in mechanical properties may cause diseases or cell apoptosis. Selective cytotoxic effects of nonthermal atmospheric pressure micro-dielectric barrier discharge (DBD) plasma have been demonstrated on cancer cells. In this work, changes in the mechanical properties of a single cell induced by nonthermal atmospheric pressure micro-DBD plasma were investigated using atomic force microscopy (AFM). Two cervical cancer cell lines (HeLa and SiHa) and normal human fibroblast cells (HFBs) were exposed to micro-DBD plasma for various exposure times. The elasticity of a single cell was determined by force-distance curve measurement using AFM. Young's modulus was decreased by plasma treatment for all cells. The Young's modulus of plasma-treated HeLa cells was decreased by 75% compared to nontreated HeLa cells. In SiHa cells and HFBs, elasticity was decreased slightly. Chemical changes induced by the plasma treatment, which were observed by Raman spectroscopy, were also significant in HeLa cells compared to SiHa cells and HFBs. These results suggested that the molecular changes induced by micro-DBD plasma were related to cell mechanical changes.

X-ray radiation promotes the metastatic potential of tongue squamous cell carcinoma cells via modulation of biomechanical and cytoskeletal properties

This study investigated the metastatic potential of tongue squamous cell carcinoma (TSCC) cells after X-ray irradiation as well as radiation-induced changes in the biomechanical properties and cytoskeletal structure that are relevant to metastasis. Tca-8113 TSCC cells were X-ray-irradiated at increasing doses (0, 1, 2, or 4 Gy), and 24 h later, migration was evaluated with the wound healing and transwell migration assays, while invasion was assessed with the Matrigel invasion assay. Confocal and atomic force microscopy were used to examine changes in the structure of the actin cytoskeleton and Young's modulus (cell stiffness), respectively. X-ray radiation induced dose-dependent increases in invasive and migratory potentials of cells relative to unirradiated control cells (p < 0.05). The Young's modulus of irradiated cells was decreased by radiation exposure (p < 0.05), which was accompanied by alterations in the integrity and organization of the cytoskeletal network, as evidenced by a decrease in the signal intensity of actin fibers (p < 0.05). X-ray irradiation enhanced migration and invasiveness in Tca-8113 TSCC cells by altering their biomechanical properties and the organization of the actin cytoskeleton. A biomechanics-based analysis can provide an additional platform for assessing tumor response to radiation and optimization of cancer therapies.

A Study on the Alterations in Skin Viscoelasticity before and after an Intradermal Administration of Growth Factor

Background:

While photo-aging is believed to be preventable by the complete blockage of ultraviolet rays, there is no epoch-making method except sing fillers or autologous fat injection, for rejuvenating the skin once it has aged.

Objective:

Our group developed a new method for rejuvenating aged skin by the direct intradermal injection of basic fibroblast growth factor, the first method of its kind in the world. In this paper we report the results of long-term follow-up observations and alterations in skin viscoelasticity before and after this treatment.

Materials and Methods:

A single dose of growth factor was injected directly into aged skin of the dorsal surface of the hand intradermally. The skin viscoelasticity of 50 treated cases was measured by a cutometer just before the treatment and at 1, 3, 6, and 9 months after treatment, respectively.

Results:

We observed the following rejuvenating effects: improved skin softness, gradual improvement of turgor, improved thickness of atrophied skin, and greatly improved viscoelasticity which reveals the improvement of biomechanical properties of the treated aged skin. According to the comparisons of viscoelasticity between pre- and post-treatment, the rejuvenated changes of R2 and R7 values were comparable to an age difference of more than 20 years.

Conclusion:

This method was confirmed to have excellent effects in rejuvenating aged skin safely and reliably including biomechanical properties. With this advance, we expect conventional non-physiological skin rejuvenating treatments to be replaced by a much more fundamental method using one-time injections of the growth factor.