Objective
To describe effects of non‐ablative erbium‐doped:yttrium‐aluminium‐garnet (Er:YAG) laser on vaginal atrophy induced by iatrogenic menopause in the ewe.
Design
Animal experimental, randomised, sham and estrogen‐treatment controlled study with blinding for primary outcome.
Setting
KU Leuven, Belgium.
Sample
Twenty‐four ewes.
Methods
Menopause was surgically induced, after which the ewes were randomised to three groups receiving vaginal Er:YAG laser application three times, with a 1‐month interval; three sham manipulations with a 1‐month interval; or estrogen replacement and sham manipulations. At given intervals, ewes were clinically examined and vaginal wall biopsies were taken. Vaginal compliance was determined by passive biomechanical testing from explants taken at autopsy.
Main outcome measures
Vaginal epithelial thickness (primary), composition of the lamina propria (collagen, elastin, glycogen and vessel content), vaginal compliance, clinical signs.
Results
Animals exposed to Er:YAG laser application and sham manipulation, but not to estrogens, displayed a significant and comparable increase in vaginal epithelial thickness between baseline and 7 days after the third application (69% and 67%, respectively, both P < 0.0008). In laser‐treated ewes, temporary vaginal discharge and limited thermal injury were observed. Estrogen‐substituted ewes displayed a more prominent increase in epithelial thickness (202%; P < 0.0001) and higher vaginal compliance (P < 0.05). None of the interventions induced changes in the lamina propria.
Conclusions
Vaginal Er:YAG laser has comparable effect to sham manipulation in menopausal ewes.
Tweetable abstract
Vaginal Er:YAG laser has comparable effect to sham manipulation in menopausal ewes #LASER #GSM #RCT.
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Collagen fibers and their orientation greatly influence an artery's mechanical characteristics, determining its transversely isotropic behavior. It is generally assumed that these fibers are deposited along a preferred direction to maximize the load bearing capacity of the vessel wall. This implies a large spatial variation in collagen orientation which can be reconstructed in numerical models using so-called reorientation algorithms. Until now, these algorithms have used the classical continuum mechanics modeling framework which requires knowledge of tissue-level parameters and the artery's stressfree reference state, which is inaccessible in a clinical context. We present an algorithm to compute the preferred fiber distribution compatible with the constrained mixture theory, which orients two collagen fiber families according to the loading experienced by the isotropic non-collagenous extracellular matrix, without requiring prior knowledge of the stress-free state. Because consensus is lacking whether stress or stretch is the determining factor behind the preferred fiber distribution, we implemented both approaches and compared the results with experimental microstructural data of an abdominal aorta. The stress-based algorithm was able to describe several experimentally observed transitions of the fiber distribution across the intima, media and adventitia.
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