Compromised Muscle Properties in a Severe Hypophosphatasia Murine Model.

Hypophosphatasia (HPP) is a rare metabolic bone disorder characterized by low levels of tissue non-specific alkaline phosphatase (TNAP) that causes under-mineralization of the bone, leading to bone deformity and fractures. In addition, patients often present with chronic muscle pain, reduced muscle strength, and an altered gait. In this work, we explored dynamic muscle function in a homozygous TNAP knockout mouse model of severe juvenile onset HPP. We found a reduction in skeletal muscle size and impairment in a range of isolated muscle contractile properties. Using histological methods, we found that the structure of HPP muscles was similar to healthy muscles in fiber size, actin and myosin structures, as well as the α-tubulin and mitochondria networks. However, HPP mice had significantly fewer embryonic and type I fibers than wild type mice, and fewer metabolically active NADH+ muscle fibers. We then used oxygen respirometry to evaluate mitochondrial function and found that complex I and complex II leak respiration were reduced in HPP mice, but that there was no disruption in efficiency of electron transport in complex I or complex II. In summary, the severe HPP mouse model recapitulates the muscle strength impairment phenotypes observed in human patients. Further exploration of the role of alkaline phosphatase in skeletal muscle could provide insight into mechanisms of muscle weakness in HPP.

Cervical Ripening Efficacy of Synthetic Osmotic Cervical Dilator Compared With Oral Misoprostol at Term: A Randomized Controlled Trial.

OBJECTIVE: To evaluate whether a synthetic osmotic cervical dilator is noninferior to oral misoprostol for cervical ripening. METHODS: In an open-label, noninferiority randomized trial, pregnant women undergoing induction of labor at 37 weeks of gestation or more with Bishop scores less than 6 were randomized to either mechanical cervical dilation or oral misoprostol. Participants in the mechanical dilation group underwent insertion of synthetic osmotic cervical dilator rods, and those in the misoprostol group received up to six doses of 25 micrograms orally every 2 hours. After 12 hours of ripening, oxytocin was initiated, with artificial rupture of membranes. Management of labor was at the physician's discretion. The primary outcome was the proportion of women achieving vaginal delivery within 36 hours of initiation of study intervention. Secondary outcomes included increase in Bishop score, mode of delivery, induction-to-delivery interval, total length of hospital stay, and patient satisfaction. On the basis of a noninferiority margin of 10%, an expected primary outcome frequency of 65% for misoprostol and 71% for mechanical methods, and 85% power, a sample size of 306 participants was needed. RESULTS: From November 2018 through January 2021, 307 women were randomized, with 151 evaluable participants in the synthetic osmotic cervical dilator group and 152 in the misoprostol group (there were four early withdrawals). The proportion of women achieving vaginal delivery within 36 hours was higher with mechanical cervical dilation compared with misoprostol (61.6% vs 59.2%), with an absolute difference of 2.4% (95% CI -9% to 13%), indicating noninferiority for the prespecified margin. No differences were noted in the mode of delivery. Tachysystole was more frequent in the misoprostol group (70 [46.4%] vs 35 [23.3%]; P=.01). Participants in the synthetic osmotic cervical dilator group reported better sleep, less unpleasant abdominal sensations, and lower pain scores (P<.05). CONCLUSION: Synthetic osmotic cervical dilator is noninferior to oral misoprostol for cervical ripening. Advantages of synthetic osmotic cervical dilator include a better safety profile and patient satisfaction, less tachysystole, lower pain scores, and U.S. Food and Drug Administration approval. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT03670836. FUNDING SOURCE: Medicem Technology s.r.o., Czech Republic.

Second harmonic generation characterization of collagen in whole bone.

Bone is a unique biological composite material made up of a highly structured collagen mesh matrix and mineral deposits. Although mineral provides stiffness, collagen's secondary organization provides a critical role in bone elasticity. Here, we performed polarimetric analysis of bone collagen fibers using second harmonic generation (SHG) imaging to evaluate lamella sheets and collagen fiber integrity in intact cranial bone. Our polarimetric data was fitted to a model accounting for diattenuation, polarization cross-talk, and birefringence. We compared our data to the fitted model and found no significant difference between our polarimetric observation and the representation of these scattering properties up to 70 µm deep. We also observed a loss of resolution as we imaged up to 70 µm deep into bone but a conservation of polarimetric response. Polarimetric SHG allows for the discrimination of collagen lamellar sheet structures in intact bone. Our work could allow for label-free identification of disease states and monitor the efficacy of therapies for bone disorders.