The frequency of pulsatile release of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) is high in the breeding season and low in the nonbreeding season. These alterations in the patterns of GnRH and LH release are due to an interaction of daylength and gonadal steroid negative feedback. A vast amount of data indicates that steroid-responsive neural systems may play a role in regulating seasonal changes in GnRH release. One candidate system is neuropeptide Y (NPY). To determine the independent and interactive influences of photoperiod and steroid exposure on NPY mRNA levels, we used hypothalamic tissue from four groups (n = 4 per group) of castrated male sheep that were simultaneously housed in photochambers and exposed to: (1) a 16L:8D photoperiod (LD); (2) LD and implanted with testosterone (LD + T); (3) a 10L:14D photoperiod (SD), and (4) SD + T. Circulating levels of T averaged 2.8 ± 0.2 ng/ml in implanted animals, but were undetectable in nonimplanted males. Mean LH levels were significantly reduced (p < 0.01) in the LD + T group as compared with the other groups which did not differ from each other. The silver grain area per NPY neuron in the arcuate nucleus, as assessed by in situ hybridization, was inversely related to mean LH values, with the grain area per cell being significantly greater (p < 0.05) for LD + T males than for all other groups which did not differ from each other. NPY cell numbers were not significantly different (p > 0.10) among the treatment groups. These results show that NPY mRNA expression is increased in male sheep during a LD photoperiod in a T-dependent manner. Our data are consistent with the idea that NPY is involved in the seasonal regulation of GnRH and LH release in the male sheep.
The ability of steroids to inhibit LH secretion is enhanced during undernutrition. To identify potential hypothalamic sites at which this enhancement may occur, we examined LH secretion in feed-restricted or fed young wethers treated with locally administered metabolites of testosterone. In experiment 1, microimplants containing crystalline estradiol-17beta (E) or cholesterol were administered via chronic guide tubes directed to the preoptic area (POA) or ventromedial hypothalamus (VMH) in fed or feed-restricted wethers. E treatment in the VMH decreased LH pulse frequency, pulse amplitude, and mean LH concentration in feed-restricted, but not fed, wethers. E may act in the POA to suppress LH under feed restriction, but definite conclusions cannot be drawn because of steroid-independent effects of feed restriction on LH pulse frequency. In experiment 2, the effect of dihydrotestosterone (DHT) in the VMH was determined. DHT administration to the VMH did not alter LH secretion in either feed-restricted or fed wethers. Thus the VMH is one site wherein E negative feedback is enhanced during feed restriction in the wether. In contrast, we found no evidence for enhanced responsiveness to androgen negative feedback within the VMH of feed-restricted wethers. We suggest that increased sensitivity within the VMH to E, but not to DHT, is important for suppressing LH secretion in undernourished male sheep.
Introduction: Ankle injuries that are not properly cared for can have devastating effects on a patient's health and ability to maintain an active lifestyle. Recommended outpatient surgery may be difficult to obtain for many groups of patients, including those without insurance or minority races. Patients who are of low socioeconomic status also have worse outcomes following trauma. The purpose of this study was to examine whether insurance status impacts the number of adverse events that patients face prior to receiving surgical treatment following an emergency department (ED) visit for an acute ankle injury. Methods: We conducted a retrospective chart review at two medical centers within the same healthcare system. The sample included 192 patients presenting to the ED with an unstable ankle injury between October 1, 2015-May 1, 2018. We used chi-square and t-test analysis to determine differences in rates of adverse events occurring while awaiting surgery. Results: Few (4%) patients presented as being self-pay. Neither Medicare (χ2 (1) (N = 192) = 2.389, p = .122), Medicaid (χ2 (1), (N = 192) = .084, p = .772), other insurances (χ2 (1) (N = 192) = .567, p = .452), or private insurance (χ2 (1) (N=192) = .000, p = .982) was associated with a difference in rates of adverse events. Likewise, gender (χ2 (1) (N = 192) = .402, p = .526), race (χ2 (3) (N = 192) = 2.504, p = .475), and all other demographic variables failed to show a difference in occurrence of adverse events. Those admitted to the hospital did show a lower rate of adverse events compared to those sent home from the ED (χ2 (1) (N = 192) = 5.452, p = .020). Sampled patients were admitted to the hospital at a high rate (49%). Conclusion: The sampled facilities did not have adverse event rates that differed based on insurance status or demographic features. These facilities, with hospital-based subsidy programs and higher than expected admission rates, may manage their vulnerable populations well and may indicate their efforts to eliminate health disparity are effective. [
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