Satellite cell depletion in degenerative skeletal muscle

Adult skeletal muscle has the striking ability to repair and regenerate itself after injury. This would not be possible without satellite cells, a subpopulation of cells existing at the margin of the myofiber. Under most conditions, satellite cells are quiescent, but they are activated in response to trauma, enabling them to guide skeletal muscle regeneration. In degenerative skeletal muscle states, including motor nerve denervation, advanced age, atrophy secondary to deconditioning or immobilization, and Duchenne muscular dystrophy, satellite cell numbers and proliferative potential significantly decrease, contributing to a diminution of skeletal muscle's regenerative capacity and contractility. This review will highlight the fate of satellite cells in several degenerative conditions involving skeletal muscle, and will attempt to gauge the relative contributions of apoptosis, senescence, impaired proliferative potential, and host factors to satellite cell dysfunction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44390/1/10495_2004_Article_5150572.pd

Double free-flap reconstruction of massive defects involving the lip, chin, and mandible

Two patients with massive, composite defects of the total lower lip, chin, and anterior mandible underwent double free-flap reconstruction. A fibular osteoseptocutaneous flap was used to reconstruct the mandible and floor of the mouth and a radial forearm fasciocutaneous composite flap, including the palmaris longus tendon, was used for total lower lip and chin reconstruction. Postoperatively, both patients had acceptable cosmesis, were orally competent, and recovered adequate mandibular function. Double free-flap reconstruction is indicated only in those circumstances in which composite tissue requirements or massive tissue defects preclude reconstruction with a single free-tissue transfer. © 1998 Wiley-Liss, Inc. MICROSURGERY 18:372–378, 1998Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38479/1/6_ftp.pd

Termino-lateral neurorrhaphy: The functional axonal anatomy

The goal of this study was to determine the functional axonal anatomy of a termino-lateral neurorrhaphy (TLN). We hypothesize that axons populating a TLN must relinquish functional connections with their original targets prior to establishing new connections via the TLN. Two-month-old F344 rats underwent a TLN between the left peroneal nerve and a nerve graft tunneled to the contralateral hindlimb. Three months postoperatively, an end-to-end neurorrhaphy was performed between the nerve graft and the right peroneal nerve. Four months after the second operation, contractile properties and electromyographic (EMG) signals were measured in the bilateral hindlimbs. Left peroneal nerve stimulation proximal to the TLN site resulted in bilateral extensor digitorum longus (EDL) and tibialis anterior (TA) muscle contractions, with significantly lower forces on the side reinnervated by TLN. Evoked EMGs demonstrated that the right and left hindlimb musculature were electrically discontinuous following TLN. These data support our hypothesis that axons can form functional connections via a TLN, but they must first relinquish functional connections with their original targets. © 2000 Wiley-Liss, Inc. MICROSURGERY 20:6–14 2000Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34923/1/2_ftp.pd

Phalloplasty: understanding the chaos

Wide variation in overall strategies and surgical specifics for masculinizing genital surgery has created a “phalloplasty chaos” that is confusing to both surgeons and patients seeking gender confirming surgery. The purpose of this article is to review masculinizing genital confirming surgery, or “phalloplasty”, focusing on specific goals and categorizing each component of the surgical process. Experienced surgeons from several high-volume centers review and categorize the commonly employed strategies and techniques for gender confirming phalloplasty, including the permutations of approaches to cutaneous flap for phallic construction, the sequence and staging of procedures, and strategies for urethral construction. There is no clear advantage or reduction in complications associated with particular sequences of urethral and phallic reconstruction. Because no single technique or staging strategy has proven superior for gender confirming genital surgery, it is paramount that surgeons are knowledgeable of all available options and the associated advantages, disadvantages, and risks

Vaginal Canal Reconstruction in Penile Inversion Vaginoplasty with Flaps, Peritoneum, or Skin Grafts: Where Is the Evidence?

BACKGROUND: To optimize neovaginal dimensions, several modifications of the traditional penile inversion vaginoplasty are described. Options for neovaginal lining include skin grafts, scrotal flaps, urethral flaps, and peritoneum. Implications of these techniques on outcomes remain limited. METHODS: A systematic review of recent literature was performed to assess evidence on various vaginal lining options as adjunct techniques in penile inversion vaginoplasty. Study characteristics, neovaginal depth, donor-site morbidity, lubrication, and complications were analyzed in conjunction with expert opinion. RESULTS: Eight case series and one cohort study representing 1622 patients used additional skin grafts when performing penile inversion vaginoplasty. Neovaginal stenosis ranged from 1.2 to 12 percent, and neovaginal necrosis ranged from 0 to 22.8 percent. Patient satisfaction with lubrication was low in select studies. Three studies used scrotal flaps to line the posterior vaginal canal. Average neovaginal depth was 12 cm in one study, and neovaginal stenosis ranged from 0 to 6.3 percent. In one study of 24 patients, urethral flaps were used to line the neovagina. Neovaginal depth was 11 cm and complication rates were comparable to other series. Two studies used robotically assisted peritoneal flaps with or without skin grafts in 49 patients. Average neovaginal depth was approximately 14 cm, and complication rates were low. CONCLUSIONS: Skin grafts, scrotal flaps, urethral flaps, and peritoneal flaps may be used to augment neovaginal canal dimensions with minimal donor-site morbidity. Further direct comparative data on complications, neovaginal depth, and lubrication are needed to assess indications in addition to advantages and disadvantages of the various lining options

Tissue Engineering of Recellularized Small-Diameter Vascular Grafts

A tissue-engineered small-diameter arterial graft would be of benefit to patients requiring vascular reconstructive procedures. Our objective was to produce a tissue-engineered vascular graft with a high patency rate that could withstand arterial pressures. Rat arteries were acellularized with a series of detergent solutions, recellularized by incubation with a primary culture of endothelial cells, and implanted as interposition grafts in the common femoral artery. Acellular grafts that had not been recellularized were implanted in a separate group of control animals. No systemic anticoagulants were administered. Grafts were explanted at 4 weeks for definitive patency evaluation and histologic examination; 89% of the recellularized grafts and 29% of the control grafts remained patent. Elastin staining demonstrated the preservation of elastic fibers within the media of the acellular grafts before implantation. Immunohistochemical staining of explanted grafts demonstrated a complete layer of endothelial cells on the lumenal surface in grafts that remained patent. Smooth muscle cells were observed to have repopulated the vessel walls. The mechanical properties of the matrix were comparable to native vessels. Such a strategy may present an alternative to autologous harvest of small vessels for use in vascular bypass procedures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63381/1/ten.2005.11.778.pd

Evaluation of BMI as a Risk Factor for Complications following Gender-affirming Penile Inversion Vaginoplasty

Background:. Gender affirmation surgery (GAS) has a positive impact on the health of transgender patients; however, some centers employ body mass index (BMI) as a strict selection criterion for surgical candidacy. Several single-center studies have found no clear correlation between BMI and complication rates. We conducted a retrospective multicenter study at 2 university-based centers to test the null hypothesis: obesity is not a significant determinant of the risk of acute surgical complications in patients undergoing penile inversion vaginoplasty (PIV). Methods:. This is a retrospective chart review of all adult patients at the University of Michigan and the University of Miami undergoing gender-affirming PIV with minimum follow-up time of 3 months between 1999 and 2017. A logistic regression model of analysis is used to examine the predictive factors for surgical complications and delayed revision urethroplasty in our patient sample. Results:. One hundred and one patients met inclusion criteria for this study. The mean BMI at the time of procedure was 26.9kg/m2 (range 17.8–48.2). Seventeen patients (16.8%) had major complications and 36 patients (35.6%) had minor complications. On logistic regression analysis, none of the recorded covariates were significant predictors of delayed revision urethroplasty or major, minor, or any complications. Conclusions:. We found that obese patients can safely undergo GAS and that BMI alone should not preclude appropriately selected patients from undergoing GAS. We acknowledge that selection based on overall health and other medical comorbidities is certainly warranted for gender-affirming PIV and all other surgical procedures

Trends in Gender-affirming Surgery in Insured Patients in the United States

Background:. An estimated 0.6% of the U.S. population identifies as transgender and an increasing number of patients are presenting for gender-related medical and surgical services. Utilization of health care services, especially surgical services, by transgender patients is poorly understood beyond survey-based studies. In this article, our aim is 2-fold; first, we intend to demonstrate the utilization of datasets generated by insurance claims data as a means of analyzing gender-related health services, and second, we use this modality to provide basic demographic, utilization, and outcomes data about the insured transgender population. Methods:. The Truven MarketScan Database, containing data from 2009 to 2015, was utilized, and a sample set was created using the Gender Identity Disorder diagnosis code. Basic demographic information and utilization of gender-affirming procedures was tabulated. Results:. We identified 7,905 transgender patients, 1,047 of which underwent surgical procedures from 2009 to 2015. Our demographic results were consistent with previous survey-based studies, suggesting transgender patients are on average young adults (average age = 29.8), and geographically diverse. The most common procedure from 2009 to 2015 was mastectomy. Complications of all gender-affirming procedures was 5.8%, with the highest rate of complications occurring with phalloplasty. There was a marked year-by-year increase in utilization of surgical services. Conclusion:. Transgender care and gender confirming surgery are an increasing component of health care in the United States. The data contained in existing databases can provide demographic, utilization, and outcomes data relevant to providers caring for the transgender patient population