Publications by authors named "David R Mann"

Objective: Surgical society conferences play a vital role in academic medicine, offering exposure to subspecialties, networking, and research presentation opportunities for surgical residents. However, the rising costs of attendance pose financial challenges, potentially deterring participation. We aimed to assess changes in conference costs, travel policies, and expenses for general surgery residents in North Carolina (NC) and South Carolina (SC) general surgery residency programs.

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Objective: A paucity of formal leadership training programs exists for residents, and outcomes of those are limited in reporting. Based on a robust needs assessment, our program created a longitudinal cohort curriculum, Future Surgical Leaders, for residents and fellows of all levels to provide training in nontechnical skills. Our objective was to evaluate surgical resident short-term outcomes and satisfaction with the Future Surgical Leaders (FSL) curriculum.

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Introduction: Neoadjuvant chemoradiation therapy (NCRT) for cT1b esophageal cancer is not recommended despite the risk of pathologic upstaging with increased depth of penetration. We aimed to (1) define the rate of and factors associated with pathologic upstaging, (2) describe current trends in treatments, and (3) compare overall survival (OS) with and without NCRT for surgically resected cT1b lesions.

Methods: We used the 2020 National Cancer Database to identify patients with cT1b N0 esophageal cancer with or without pathologic upstaging who underwent removal of their tumor.

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Background: The spread of Coronavirus Disease 2019 (COVID-19) in the United States has centered the role of natural hazards such as pandemics into the public health sphere. The impacts of these hazards disproportionately affect people with disabilities, who are frequently in situations of social, political, or economic disadvantage. Because of these disadvantages, people with disabilities may have less access to necessary resources and services, putting them at risk due to unmet health needs.

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Introduction The fellowship match process is convoluted, with each specialty having its match on its timeline- with some programs having a Post Graduate Year (PGY) 4-year or 5-year match. This study aims to identify tangible recommendations for osteopathic surgery residents to use to improve their applications and, ultimately, the success rate for matching into post-graduate fellowship training. Methods In October 2021, as a part of the American College of Osteopathic Surgeons (ACOS) Strategic Planning efforts, the ACOS Resident Student Section sent a questionnaire to the listed email contact for each surgical fellowship program.

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A 77-year-old male with a history of chronic obstructive pulmonary disease (COPD) who presented with cough, congestion, and stridor and was found to have a near obstructing tracheal mass. He subsequently underwent excision of the mass. On pathologic examination, it was diagnosed as fibromyxoma of the trachea.

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The original version of this article unfortunately contained a mistake in the article title. The text "Rhode Island's" inadvertently omitted in the original publication.

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Purpose The Workforce Innovation and Opportunity Act strengthens the vocational rehabilitation program's focus on providing early intervention services to keep workers with disabilities in the workforce. At the same time, some have suggested that short-term disability insurance (STDI) programs may hold promise as an early intervention service, helping people with disabilities stay in the labor force and avoid needing longer-term benefits. Rhode Island is one of five states with a mandatory STDI program.

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Disability status-experiencing a functional limitation caused by a health condition-is dynamic throughout the life cycle, even during adolescence and young adulthood. We use data from the 1997 cohort of the National Longitudinal Survey of Youth to better understand these dynamics, examining how health condition and limitation statuses evolve during adolescence and young adulthood as well as how changes in these characteristics are related to survey nonresponse and attrition. Health condition and limitation dynamics are evident in our data: the proportion of sample members who reported having a limitation in their activities for any interview increased from approximately 12 % during the initial interview (when sample members were 12 to 17 years old) to almost 25 % 13 years later.

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Puberty in primates is first delayed by a neurobiological switch that arrests pulsatile GnRH release during infancy and then triggered, after a protracted period of juvenile development, by resurgence in intermittent release of this hypothalamic peptide. The purpose of this chapter is to review recent studies conducted in our laboratories to begin to examine the role of thyroid hormone (TH) in governing this postnatal development of pulsatile GnRH release in primates and therefore the timing of puberty in these species. The male rhesus monkey was used as the experimental model and TH activity was manipulated by surgical and chemical thyroidectomy on the one hand, and by thyroxine (T(4)) and triiodothyronine (T(3)) replacement on the other.

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Introduction: We have shown previously that treatment with pegylated leptin peptide receptor antagonist 2 (PEG-LPrA2) reduced the expression of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor type 2 (VEGFR2) and growth of 4T1-breast cancer (BC) in syngeneic mice. In this investigation, PEG-LPrA2 was used to evaluate whether the inhibition of leptin signaling has differential impact on the expression of pro-angiogenic and pro-proliferative molecules and growth of human estrogen receptor-positive (ER+) and estrogen receptor-negative (ER-) BC xenografts hosted by immunodeficient mice.

Methods: To test the contribution of leptin signaling to BC growth and expression of leptin-targeted molecules, PEG-LPrA2 treatment was applied to severe immunodeficient mice hosting established ER+ (MCF-7 cells; ovariectomized/supplemented with estradiol) and ER- (MDA-MB231 cells) BC xenografts.

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In humans, circulating leptin levels are low in early childhood and rise until puberty, whereas the reverse occurs for the soluble leptin receptor (sOB-R). In women, leptin remains high and sOB-R remains low, but in men leptin declines after adolescence and sOB-R increases. These observations suggest that leptin may regulate the production of sOB-R, and that the increased testosterone in adolescent boys may be responsible for the gender differences in leptin and sOB-R.

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Female leptin deficient (ob/ob) mice exhibit abnormal ovarian folliculogenesis resulting in an impaired ability to reproduce. This effect may be related to the hypogonadotropic state of these animals, or leptin may directly modulate ovarian follicle development. In the present study we assessed whether exogenous gonadotropin administration would normalize folliculogenesis and induce ovulation in immature ob/ob animals.

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Leptin-deficient (ob/ob) male mice are morbidly obese and exhibit impaired reproductive function. The objective of this study was to assess the effect of a leptin deficiency on testicular morphology, germ cell development, apoptotic activity within germ cells, and expression levels of apoptosis-related genes in the testis. Sixteen week-old ob/ob male mice (n = 8) and controls (n = 8) were killed, and their reproductive organs were weighed.

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Objectives: Subnormal leptin levels in low birth weight infants may allow for catch-up growth during infancy. Scant data are available that relate growth with circulating leptin during normal infancy in primates. The current study objective was to examine the association between serum leptin, its soluble receptor (sOB-R), testosterone and IGF-I concentrations, and body weight during infancy in male rhesus monkeys.

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Leptin purportedly plays an important role in pubertal development in a number of mammalian species. Adult leptin-deficient (ob/ob) female mice are infertile, but the mechanisms responsible for the reproductive failure have not been fully elucidated. The major objective of the current study was to assess the effects of a leptin deficiency on ovarian folliculogenesis and apoptosis.

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We determined developmental changes in circulating levels of the soluble leptin receptor (sOB-R), leptin, and gonadal hormones in human subjects. In both sexes the rise in leptin with age was associated with a decline in sOB-R, and age-related changes in both parameters preceded the pubertal rise in gonadal hormones. Leptin levels above 10 ng/ml were a strong predictor of sOB-R concentrations, but this predictive value decreased as leptin declined.

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Seasonal fluctuations in immune status have been documented for avian and mammalian populations. During the late summer and early fall, immune function is bolstered to help animals cope with the more physiologically demanding winter. The environmental cue for these seasonal changes is apparently decreasing photoperiod.

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Sexual development after birth in rodents, nonhuman primates, and humans is driven by the gonadotropin-releasing hormone (GnRH) pulse generator. During the neonatal period in primates, pulsatile GnRH discharge from the medial basal hypothalamus drives an active period of pituitary gonadotropin and gonadal hormone secretion. During the transition from the neonatal to the juvenile period, however, the activity of the GnRH pulse generator is restrained or arrested and gonadotropin and gonadal hormone secretion enters a quiescent period that continues until the onset of puberty.

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Heterologous radioimmunoassays (RIA) for macaque LH and FSH were validated for the measurement of these hormones in the sooty mangabey and mangabey pituitary LH was characterized relative to rhesus monkey LH. Dilutions of a pituitary mangabey extract and a partially purified preparation of mangabey LH ran parallel to a rhesus monkey standard (LER 1909-2) in the ovine-ovine (o-o) LH assay but showed some deviation from parallelism in the rhesus monkey FSH assay. The LH potency of the mangabey extract and standard were six and 190 times more potent, respectively, than LER 1909-2 in the LH RIA.

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