The adipokine, leptin (LEP), is a hormonal gateway, signaling energy stores to appetite-regulatory neurons, permitting reproduction when stores are sufficient. Dual-labeling for LEP receptors (LEPRs) and gonadotropins or GH revealed a 2-fold increase in LEPR during proestrus, some of which was seen in LH gonadotropes. We therefore investigated LEPR functions in gonadotropes with Cre-LoxP technology, deleting the signaling domain of the LEPR (Lepr-exon 17) with Cre-recombinase driven by the rat LH-β promoter (Lhβ-cre). Selectivity of the deletion was validated by organ genotyping and lack of LEPR and responses to LEP by mutant gonadotropes. The mutation had no impact on growth, body weight, the timing of puberty, or pregnancy. Mutant females took 36% longer to produce their first litter and had 50% fewer pups/litter. When the broad impact of the loss of gonadotrope LEPR on all pituitary hormones was studied, mutant diestrous females had reduced serum levels of LH (40%), FSH (70%), and GH (54%) and mRNA levels of Fshβ (59%) and inhibin/activin β A and β B (25%). Mutant males had reduced serum levels of GH (74%), TSH (31%), and prolactin (69%) and mRNA levels of Gh (31%), Ghrhr (30%), Fshβ (22%), and glycoprotein α-subunit (Cga) (22%). Serum levels of LEP and ACTH and mRNA levels of Gnrhr were unchanged. However, binding to GnRH receptors was reduced in LEPR-null LH or FSH gonadotropes by 82% or 89%, respectively, in females (P < .0001) and 27% or 53%, respectively, in males (P < .03). This correlated with reductions in GnRH receptor protein immunolabeling, suggesting that LEP's actions may be posttranscriptional. Collectively, these studies highlight the importance of LEP to gonadotropes with GnRH-binding sites and activin as potential targets. LEP may modulate population growth, adjusting the number of offspring to the availability of food supplies.

3.

Purpose Instability of the proximal tibioibular joint (PTFJ) can be treated with bicortical suspension (BCS) ixation. However, the ideal location, orientation, and coniguration to apply one or two BCS devices are not clear. Methods A inite-element model of the PTFJ was created from a female adult's CT dataset. Anterior and posterior ligaments at the PTFJ were modeled and suppressed to simulate stable and unstable joints. Fifty-six models simulated 56 device placements along guiding tunnel lines that connect eight entry locations on the ibular head to seven exit points on the anteromedial tibia. Doubling device stifness created 56 more models. Combing any two placements created 1176 double-device conigurations which were categorized to be crossed, divergent or parallel. Displacement of the ibular head relative to the ixed tibia under 100 N anterolateral and posteromedial forces was assessed. Results Diferent placements had 2.1-27.9 mm translation with 0.7-8.9° internal rotation under anterolateral loading, and 1.8-5.2 mm translation with 6.1-7.9° external rotation under posteromedial loading. More transverse and superior orientations were associated with smaller anterolateral translation; more posterior and superior entry locations were associated with smaller internal rotation. The median (IQR) reductions in anterolateral translation by doubling device stifness and by adding a second device were 0.8 (IQR 0.5-1.0) and 0.8 (IQR 0-6.1) mm, respectively. The type of double-device conigurations had no signiicant efect on ibular motion. Conclusion Surgeons should drill the guiding tunnel superiorly and transversely to ensure the optimal restoration of the PTFJ anterolateral stability.

Background: Ulnar collateral ligament reconstruction (UCLR) is the gold standard for treating ulnar collateral ligament injuries in throwing athletes who have failed conservative treatment. There are several described techniques that produce successful and reproducible outcomes. In addition, there is biomechanical evidence that supports hybrid fixation of the graft with a docking technique on the humeral side and suspensory fixation on the ulnar side. However, as of this writing there are no clinical studies that have reported results. This retrospective case series is the first of its kind to report on clinical outcomes following UCLR with hybrid suspensory fixation. Methods: Fifty throwing athletes who underwent ULCR with hybrid suspensory fixation from 2010-2017 by one of 5 surgeons at a single institution were available at a median follow-up of 7 years. Return to sport, level of sport, and postoperative complications were recorded at final follow-up. Results: A total of 50 patients were included in final analysis. Nearly all were able to return to sport at the same level or higher (48/50, 96%). One of these 50 athletes (2%) played professionally, 27 (54%) played collegiately, and 21 (42%) played at the high school level. Seven patients (14%) underwent reoperation following the index procedure. The median (interquartile range) Quick Disabilities of the Arm, Shoulder, and Hand questionnaire score was 0.098 (0-4.5) at final follow-up. Conclusion: Hybrid suspensory fixation is a safe and effective technique for UCLR in the throwing athlete. Throwers can expect to return to sport at a very high rate with low risks for postoperative complications.

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