Accuracy of Predicted Resection Weights in Breast Reduction Surgery

Background:

Many insurance carriers continue to deny coverage for reduction mammaplasty unless a minimum amount of resected breast tissue per breast is achieved during surgery. This study investigates the accuracy of preoperative prediction that a minimum weight of 500 g can be resected and evaluates potential risk factors for not meeting this insurance requirement.

Methods:

A retrospective review was performed on 445 patients with bilateral symptomatic macromastia who sought consultation for breast reduction surgery from 2007 to 2012. Women were included for analysis if they had documented predicted resection weights and underwent small-to-moderate breast reduction (< 1,000 g per side; n = 323). Relevant demographic information, mean predicted resection weight, and the mean actual resection weight were collected for analysis.

Results:

Surgeon prediction of resection weight being over 500 g had a positive predictive value of 73%. In 61 patients (19%), the predicted weights were ≥ 500 g, but the actual weights were < 500 g. Thirty percentage of these 61 patients did not meet either Schnur or minimum weight requirements. Women with a body mass index < 30 were at significantly increased odds (odds ratio, 3.76; 95% confidence interval, 1.89–7.48; P = 0.002) of not meeting the minimum weight requirement at surgery compared with patients with a body mass index ≥ 30.

Conclusions:

The common insurance criterion of removing ≥ 500 g per breast during breast reduction surgery are not met in a distinct cohort of women who are clinically appropriate candidates. This risk is particularly increased in nonobese women possibly due to proportionately smaller breast mass compared with obese women.

Electrical stimulation of renal nerves for modulating urine glucose excretion in rats

Background

The role of the kidney in glucose homeostasis has gained global interest. Kidneys are innervated by renal nerves, and renal denervation animal models have shown improved glucose regulation. We hypothesized that stimulation of renal nerves at kilohertz frequencies, which can block propagation of action potentials, would increase urine glucose excretion. Conversely, we hypothesized that low frequency stimulation, which has been shown to increase renal nerve activity, would decrease urine glucose excretion.

Methods

We performed non-survival experiments on male rats under thiobutabarbital anesthesia. A cuff electrode was placed around the left renal artery, encircling the renal nerves. Ureters were cannulated bilaterally to obtain urine samples from each kidney independently for comparison. Renal nerves were stimulated at kilohertz frequencies (1–50 kHz) or low frequencies (2–5 Hz), with intravenous administration of a glucose bolus shortly into the 25–40-min stimulation period. Urine samples were collected at 5–10-min intervals, and colorimetric assays were used to quantify glucose excretion and concentration between stimulated and non-stimulated kidneys. A Kruskal-Wallis test was performed across all stimulation frequencies (α = 0.05), followed by a post-hoc Wilcoxon rank sum test with Bonferroni correction (α = 0.005).

Results

For kilohertz frequency trials, the stimulated kidney yielded a higher average total urine glucose excretion at 33 kHz (+ 24.5%; n = 9) than 1 kHz (− 5.9%; n = 6) and 50 kHz (+ 2.3%; n = 14). In low frequency stimulation trials, 5 Hz stimulation led to a lower average total urine glucose excretion (− 40.4%; n = 6) than 2 Hz (− 27.2%; n = 5). The average total urine glucose excretion between 33 kHz and 5 Hz was statistically significant (p < 0.005). Similar outcomes were observed for urine flow rate, which may suggest an associated response. No trends or statistical significance were observed for urine glucose concentrations.

Conclusion

To our knowledge, this is the first study to investigate electrical stimulation of renal nerves to modulate urine glucose excretion. Our experimental results show that stimulation of renal nerves may modulate urine glucose excretion, however, this response may be associated with urine flow rate. Future work is needed to examine the underlying mechanisms and identify approaches for enhancing regulation of glucose excretion.

Simplifying Arterial Coupling in Microsurgery-A Preclinical Assessment of an Everter Device to Aid with Arterial Anastomosis

BACKGROUND

 A novel arterial everter device was engineered to simplify microvascular coupling of arteries by reliably securing the stiff, muscular wall of arteries over coupler pins. We compare microvascular coupling with the everter device to manual suturing for arterial anastomoses in a live large animal model.

MATERIALS AND METHODS

 In this preliminary study, bilateral external femoral arteries of five male swine were exposed and sharply divided. Arteries were anastomosed using either interrupted sutures (n = 5) or the everter device and Synovis Coupler (n = 5). The efficiency in engaging coupler pins, the time taken to perform the anastomosis, and vessel patency immediately post-op and at 1-week postanastomosis were evaluated. Vessel wall injury and luminal stenosis were compared between groups using histomorphometric analyses.

RESULTS

 On an average, 80% of coupler pins engaged the vessel walls after a single pass of the everter. The average time to perform the anastomosis was significantly less when using the everter/coupler compared with manual suturing (6:35 minutes versus 25:09 minutes, p < 0.001). Immediately post-op, 100% patency was observed in both groups. At 1 week post-op, four of five (80%) of coupled arteries and all five (100%) of hand-sewn arteries were patent. The degree of arterial wall injury, neointimal formation, and luminal stenosis for patent arteries were similar between groups.

CONCLUSIONS

 Successful arterial anastomoses using the everter device with the Synovis Coupler was easier and significantly more efficient when compared with a standard hand-sewn technique. Both techniques had acceptable patency rates and similar effects on the vessel wall and intima.

Treating the Football Athlete: Coaches' Perspective from the University of Michigan

Although football is one of the most popular sports in America, its high injury incidence places concern on the injury prevention and safety of its players. This article investigates the perspectives of two National Collegiate Athletic Association Division 1 football coaches on promoting injury management and player safety while maintaining a highly competitive team. Through obtaining their coaching philosophy team management topics, effective strategies that contribute to a team culture prioritizing player well-being were identified. Interactions of football coaches with physicians and medical specialists are explored to highlight strengths that can optimize the care and treatment of football athletes.

Comparison of patient-reported outcomes after traumatic upper extremity amputation: Replantation versus prosthetic rehabilitation

BACKGROUND

After major upper extremity traumatic amputation, replantation is attempted based upon the assumption that outcomes for a replanted limb exceed those for revision amputation with prosthetic rehabilitation. While some reports have examined functional differences between these patients, it is increasingly apparent that patient perceptions are also critical determinants of success. Currently, little patient-reported outcomes data exists to support surgical decision-making in the setting of major upper extremity traumatic amputation. Therefore, the purpose of this study is to directly compare patient-reported outcomes after replantation versus prosthetic rehabilitation.

METHODS

At three tertiary care centers, patients with a history of traumatic unilateral upper extremity amputation at or between the radiocarpal and elbow joints were identified. Patients who underwent either successful replantation or revision amputation with prosthetic rehabilitation were contacted. Patient-reported health status was evaluated with both DASH and MHQ instruments. Intergroup comparisons were performed for aggregate DASH score, aggregate MHQ score on the injured side, and each MHQ domain.

RESULTS

Nine patients with successful replantation and 22 amputees who underwent prosthetic rehabilitation were enrolled. Aggregate MHQ score for the affected extremity was significantly higher for the Replantation group compared to the Prosthetic Rehabilitation group (47.2 vs. 35.1, p<0.05). Among the MHQ domains, significant advantages to replantation were demonstrated with respect to overall function (41.1 vs. 19.7, p=0.03), ADLs (28.3 vs. 6.0, p=0.03), and patient satisfaction (46.0 vs. 24.4, p=0.03). Additionally, Replantation patients had a lower mean DASH score (24.6 vs. 39.8, p=0.08).

CONCLUSIONS

Patients in this study who experienced major upper extremity traumatic amputation reported more favorable patient-reported outcomes after successful replantation compared to revision amputation with prosthetic rehabilitation.

Regenerative Peripheral Nerve Interfaces for the Treatment of Postamputation Neuroma Pain: A Pilot Study

BACKGROUND

Originally designed for prosthetic control, regenerative peripheral nerve interfaces (RPNIs) prevent neuroma formation by providing free muscle grafts as physiological targets for peripheral nerve ingrowth. We report the first series of patients undergoing RPNI implantation for treatment of symptomatic postamputation neuromas.

METHODS

A retrospective case series of all amputees undergoing RPNI implantation for treatment of symptomatic neuromas between November 2013 and June 2015 is presented. Data were obtained via chart review and phone interviews using questions derived from the Patient Reported Outcomes Measurement Information System instruments. Statistical analyses were performed using dependent sample t tests with a significance threshold of P < 0.01.

RESULTS

Forty-six RPNIs were implanted into 16 amputees for neuroma relief (3 upper extremities and 14 lower extremities). Mean age was 53.5 years (6 females and 10 males). All patients participated in postoperative phone interviews at 7.5 ± 3.4 (range: 3-15) months. Patients reported a 71% reduction in neuroma pain and a 53% reduction in phantom pain. Most patients felt satisfied or highly satisfied with RPNI surgery (75%), reporting decreased (56%) or stable (44%) levels of analgesic use. Most patients would strongly recommend RPNI surgery to a friend (88%) and would do it again if given the option (94%). Complications included delayed wound healing (n = 4) and neuroma pain at a different site (n = 2).

CONCLUSIONS

RPNI implantation carries a reasonable complication profile while offering a simple, effective treatment for symptomatic neuromas. Most patients report a significant reduction in neuroma and phantom pain with a high level of satisfaction. The physiological basis for preventing neuroma recurrence is an intriguing benefit to this approach.

Patching the safety net: establishing a free specialty care clinic in an academic medical center

We describe the collaboration between an academic medical center and a free primary care clinic that provides multi-specialty services to indigent community members. Complementary components of both institutions have engendered a system in which they broaden the array of available services, providing a prototype for other institutions to collaborate similarly.

Electrically stimulated signals from a long-term Regenerative Peripheral Nerve Interface

Despite modern technological advances, the most widely available prostheses provide little functional recovery beyond basic grasping. Although sophisticated upper extremity prostheses are available, optimal prosthetic interfaces which give patients high-fidelity control of these artificial limbs are limited. We have developed a novel Regenerative Peripheral Nerve Interface (RPNI), which consists of a unit of free muscle that has been neurotized by a transected peripheral nerve. In conjunction with a biocompatible electrode on the muscle surface, the RPNI facilitates signal transduction from a residual peripheral nerve to a neuroprosthetic limb. The purpose of this study was to explore signal quality and reliability in an RPNI following an extended period of implantation. Following a 14-month maturation period, electromyographic signal generation was evaluated via electrical stimulation of the innervating nerve. The long-term RPNI was viable and healthy, as demonstrated by evoked compound muscle action potentials as well as histological tissue analysis. Signals exceeding 4 mV were successfully acquired and amplitudes were consistent across multiple repetitions of applied stimuli. There were no evident signs of muscle denervation, significant scar tissue, or muscle necrosis. This study provides further evidence that after a maturation period exceeding 1 year, reliable and consistent signals can still be acquired from an RPNI.

Chronic recording of hand prosthesis control signals via a regenerative peripheral nerve interface in a rhesus macaque

OBJECTIVE

Loss of even part of the upper limb is a devastating injury. In order to fully restore natural function when lacking sufficient residual musculature, it is necessary to record directly from peripheral nerves. However, current approaches must make trade-offs between signal quality and longevity which limit their clinical potential. To address this issue, we have developed the regenerative peripheral nerve interface (RPNI) and tested its use in non-human primates.

APPROACH

The RPNI consists of a small, autologous partial muscle graft reinnervated by a transected peripheral nerve branch. After reinnervation, the graft acts as a bioamplifier for descending motor commands in the nerve, enabling long-term recording of high signal-to-noise ratio (SNR), functionally-specific electromyographic (EMG) signals. We implanted nine RPNIs on separate branches of the median and radial nerves in two rhesus macaques who were trained to perform cued finger movements.

MAIN RESULTS

No adverse events were noted in either monkey, and we recorded normal EMG with high SNR (>8) from the RPNIs for up to 20 months post-implantation. Using RPNI signals recorded during the behavioral task, we were able to classify each monkey's finger movements as flexion, extension, or rest with >96% accuracy. RPNI signals also enabled functional prosthetic control, allowing the monkeys to perform the same behavioral task equally well with either physical finger movements or RPNI-based movement classifications.

SIGNIFICANCE

The RPNI signal strength, stability, and longevity demonstrated here represents a promising method for controlling advanced prosthetic limbs and fully restoring natural movement.

Development of a Regenerative Peripheral Nerve Interface for Control of a Neuroprosthetic Limb

Background. The purpose of this experiment was to develop a peripheral nerve interface using cultured myoblasts within a scaffold to provide a biologically stable interface while providing signal amplification for neuroprosthetic control and preventing neuroma formation. Methods. A Regenerative Peripheral Nerve Interface (RPNI) composed of a scaffold and cultured myoblasts was implanted on the end of a divided peroneal nerve in rats (n = 25). The scaffold material consisted of either silicone mesh, acellular muscle, or acellular muscle with chemically polymerized poly(3,4-ethylenedioxythiophene) conductive polymer. Average implantation time was 93 days. Electrophysiological tests were performed at endpoint to determine RPNI viability and ability to transduce neural signals. Tissue samples were examined using both light microscopy and immunohistochemistry. Results. All implanted RPNIs, regardless of scaffold type, remained viable and displayed robust vascularity. Electromyographic activity and stimulated compound muscle action potentials were successfully recorded from all RPNIs. Physiologic efferent motor action potentials were detected from RPNIs in response to sensory foot stimulation. Histology and transmission electron microscopy revealed mature muscle fibers, axonal regeneration without neuroma formation, neovascularization, and synaptogenesis. Desmin staining confirmed the preservation and maturation of myoblasts within the RPNIs. Conclusions. RPNI demonstrates significant myoblast maturation, innervation, and vascularization without neuroma formation.

Treatment of heterotopic ossification through remote ATP hydrolysis

Heterotopic ossification (HO) is the pathologic development of ectopic bone in soft tissues because of a local or systemic inflammatory insult, such as burn injury or trauma. In HO, mesenchymal stem cells (MSCs) are inappropriately activated to undergo osteogenic differentiation. Through the correlation of in vitro assays and in vivo studies (dorsal scald burn with Achilles tenotomy), we have shown that burn injury enhances the osteogenic potential of MSCs and causes ectopic endochondral heterotopic bone formation and functional contractures through bone morphogenetic protein-mediated canonical SMAD signaling. We further demonstrated a prevention strategy for HO through adenosine triphosphate (ATP) hydrolysis at the burn site using apyrase. Burn site apyrase treatment decreased ATP, increased adenosine 3',5'-monophosphate, and decreased phosphorylation of SMAD1/5/8 in MSCs in vitro. This ATP hydrolysis also decreased HO formation and mitigated functional impairment in vivo. Similarly, selective inhibition of SMAD1/5/8 phosphorylation with LDN-193189 decreased HO formation and increased range of motion at the injury site in our burn model in vivo. Our results suggest that burn injury-exacerbated HO formation can be treated through therapeutics that target burn site ATP hydrolysis and modulation of SMAD1/5/8 phosphorylation.

Enabling Low-Power, Multi-Modal Neural Interfaces Through a Common, Low-Bandwidth Feature Space

Brain-Machine Interfaces (BMIs) have shown great potential for generating prosthetic control signals. Translating BMIs into the clinic requires fully implantable, wireless systems; however, current solutions have high power requirements which limit their usability. Lowering this power consumption typically limits the system to a single neural modality, or signal type, and thus to a relatively small clinical market. Here, we address both of these issues by investigating the use of signal power in a single narrow frequency band as a decoding feature for extracting information from electrocorticographic (ECoG), electromyographic (EMG), and intracortical neural data. We have designed and tested the Multi-modal Implantable Neural Interface (MINI), a wireless recording system which extracts and transmits signal power in a single, configurable frequency band. In prerecorded datasets, we used the MINI to explore low frequency signal features and any resulting tradeoff between power savings and decoding performance losses. When processing intracortical data, the MINI achieved a power consumption 89.7% less than a more typical system designed to extract action potential waveforms. When processing ECoG and EMG data, the MINI achieved similar power reductions of 62.7% and 78.8%. At the same time, using the single signal feature extracted by the MINI, we were able to decode all three modalities with less than a 9% drop in accuracy relative to using high-bandwidth, modality-specific signal features. We believe this system architecture can be used to produce a viable, cost-effective, clinical BMI.

Regenerative Peripheral Nerve Interface for Prostheses Control: Electrode Comparison

BACKGROUND

This study compared epimysial patch electrodes with intramuscular hook electrodes using monopolar and bipolar recording configurations. The purpose was to determine which strategy transduced muscle signals with better fidelity for control of myoelectric prostheses.

METHODS

One of the two electrode styles, patch (n = 4) or hook (n = 6) was applied to the left extensor digitorum longus muscle in rats. Electrodes were evaluated at the time of placement and at monthly intervals for 4 months. Evaluations consisted of evoked electromyography signals from stimulation pulses applied to the peroneal and tibial nerves in both monopolar and bipolar recording configurations.

RESULTS

Compared with hook electrodes, patch electrodes recorded larger signals of interest and minimized muscle tissue injury. A bipolar electrode configuration significantly reduced signal noise when compared with a monopolar configuration.

CONCLUSION

Epimysial patch electrodes outperform intramuscular hook electrodes during chronic skeletal muscle implantation.

Effects of vacuum suctioning and strategic drape tenting on oxygen concentration in a simulated surgical field

STUDY OBJECTIVE

To investigate the isolated and combined effects of vacuum suctioning and strategic drape tenting on oxygen concentration in an experimental setting.

DESIGN

Experimental.

SETTING

Clinical simulation center of a university-affiliated hospital.

PARTICIPANTS

Mannequin simulation of a patient undergoing facial surgery under sedation anesthesia. Supplemental oxygen was delivered via nasal cannula.

INTERVENTIONS

Vacuum suctioning and strategic drape tenting.

MEASUREMENTS

The experimental trials entailed measuring oxygen concentration around the nasal cannula continuously either in the presence or absence of a standard operating room vacuum suction system and strategic tenting of surgical drapes. The primary outcome was the time required for oxygen concentration to reach 21%.

MAIN RESULTS

In the control group (without suction or strategic tenting), a mean time of 180 seconds elapsed until the measured oxygen concentration reached 21% after cessation of oxygen delivery. Use of a vacuum suction device alone (110 seconds; P < .01) or in combination with strategic tenting (110 seconds; P < .01) significantly reduced this time. No significant benefit was seen when tenting was used alone (160 seconds; P < .30).

CONCLUSION

Use of a vacuum suction device during surgery will lower local oxygen concentration, and this in turn may decrease the risk of operating room fires. Although strategic tenting of surgical drapes has a theoretical benefit to decreasing the pooling of oxygen around the surgical site, further investigation is necessary before its routine use is recommended.

Effects of aging on osteogenic response and heterotopic ossification following burn injury in mice

Heterotopic ossification (HO) is a common and debilitating complication of burns, traumatic brain injuries, and musculoskeletal trauma and surgery. Although the exact mechanism of ectopic bone formation is unknown, mesenchymal stem cells (MSCs) capable of osteogenic differentiation are known to play an essential role. Interestingly, the prevalence of HO in the elderly population is low despite the high overall occurrence of musculoskeletal injury and orthopedic procedures. We hypothesized that a lower osteogenicity of MSCs would be associated with blunted HO formation in old compared with young mice. In vitro osteogenic differentiation of adipose-derived MSCs from old (18-20 months) and young (6-8 weeks) C57/BL6 mice was assessed, with or without preceding burn injury. In vivo studies were then performed using an Achilles tenotomy with concurrent burn injury HO model. HO formation was quantified using μCT scans, Raman spectroscopy, and histology. MSCs from young mice had more in vitro bone formation, upregulation of bone formation pathways, and higher activation of Smad and nuclear factor kappa B (NF-κB) signaling following burn injury. This effect was absent or blunted in cells from old mice. In young mice, burn injury significantly increased HO formation, NF-κB activation, and osteoclast activity at the tenotomy site. This blunted, reactive osteogenic response in old mice follows trends seen clinically and may be related to differences in the ability to mount acute inflammatory responses. This unique characterization of HO and MSC osteogenic differentiation following inflammatory insult establishes differences between age populations and suggests potential pathways that could be targeted in the future with therapeutics.

The potential roles for adipose tissue in peripheral nerve regeneration

INTRODUCTION

This review summarizes current understanding about the role of adipose-derived tissues in peripheral nerve regeneration and discusses potential advances that would translate this approach into the clinic.

METHODS

We searched PubMed for in vivo, experimental studies on the regenerative effects of adipose-derived tissues on peripheral nerve injuries. We summarized the methods and results for the 42 experiments.

RESULTS

Adipose-derived tissues enhanced peripheral nerve regeneration in 86% of the experiments. Ninety-five percent evaluated purified, cultured, or differentiated adipose tissue. These approaches have regulatory and scaling burdens, restricting clinical usage. Only one experiment tested the ability of adipose tissue to enhance nerve regeneration in conjunction with nerve autografts, the clinical gold standard.

CONCLUSION

Scientific studies illustrate that adipose-derived tissues enhance regeneration of peripheral nerves. Before this approach achieves clinical acceptance, fat processing must become automated and regulatory approval achieved. Animal studies using whole fat grafts are greatly needed for clinical translation.

Direct Mouse Trauma/Burn Model of Heterotopic Ossification

Heterotopic ossification (HO) is the formation of bone outside of the skeleton which forms following major trauma, burn injuries, and orthopaedic surgical procedures. The majority of animal models used to study HO rely on the application of exogenous substances, such as bone morphogenetic protein (BMP), exogenous cell constructs, or genetic mutations in BMP signaling. While these models are useful they do not accurately reproduce the inflammatory states that cause the majority of cases of HO. Here we describe a burn/tenotomy model in mice that reliably produces focused HO. This protocol involves creating a 30% total body surface area partial thickness contact burn on the dorsal skin as well as division of the Achilles tendon at its midpoint. Relying solely on traumatic injury to induce HO at a predictable location allows for time-course study of endochondral heterotopic bone formation from intrinsic physiologic processes and environment only. This method could prove instrumental in understanding the inflammatory and osteogenic pathways involved in trauma-induced HO. Furthermore, because HO develops in a predictable location and time-course in this model, it allows for research to improve early imaging strategies and treatment modalities to prevent HO formation.

Decellular biological scaffold polymerized with PEDOT for improving peripheral nerve interface charge transfer

Regenerative peripheral nerve interfaces (RPNIs) are for signal transfer between peripheral nerves inside the body to controllers for motorized prosthetics external to the body. Within the residual limb of an amputee, surgical construction of a RPNI connects a remaining peripheral nerve and spare muscle. Nerve signals become concentrated within the RPNI. Currently metal electrodes implanted on the RPNI muscle transfer signals but scarring around metal electrodes progressively diminishes charge transfer. Engineered materials may benefit RPNI signal transfer across the neural interface if they lower the power and charge density of the biologically meaningful signals. Poly3,4-ethylenedioxythiophene (PEDOT) is known to mediate ionic potentials allowing excitation across a critical nerve gap. We hypothesize that the capacity of an interface material to conduct electron mediated current is significantly increased by polymerized coating of PEDOT. SIS was either used plain or after PEDOT coating by electrochemical polymerization. Muscle forces are a direct representation of stimulating current distribution within an RPNI. In situ muscle forces were measured for the same muscle by electrically stimulating: a) the muscle's innervating nerve, b) directly on the muscle, c) on plain SIS laid on the muscle, and d) on SIS polymerized with PEDOT laid on the muscle. Electro-chemically coating PEDOT on SIS resulted in a thin, flexible material. PEDOT coated SIS distributed electrical stimulation more efficiently than SIS alone. Conductive polymer containing biological material allowed ionic signal distribution within the RPNI like muscle at lower charge density.

Role of anatomical region and hypoxia on angiogenic markers in adipose-derived stromal cells

BACKGROUND

Recent research into adipose-derived stem cells (ASCs) suggests that anatomical location has a major impact on the metabolic profile and differentiation capacity of ASCs. By having a better understanding of how various ASCs respond to cellular stressors such as hypoxia, which are induced during routine surgical procedures, we can facilitate future development of cell-based therapies to improve wound healing.

PATIENTS AND METHODS

Human ASCs were isolated from the superficial and deep adipose layers of four patients undergoing elective abdominoplasty. ASCs were cultured in hypoxic (1% O2, 5% CO2, and 94% N2) conditions. After 12 and 48 hours, ASCs were assessed for markers of angiogenesis by mRNA levels of vascular endothelial growth factor A (VEGF-A), vascular endothelial growth factor B (VEGF-B), and hypoxia inducible factor 1 α (HIF-1α). Western blot analysis was performed to assess levels of VEGF-A, p-NF-κB, and NF-κB. In addition, in vitro analysis of angiogenesis was performed using Matrigel assay (BD Biosciences, Franklin Lakes, NJ).

RESULTS

We observed significant increases in deep ASC's VEGF-A, VEGF-B, and HIF-1α mRNA expression compared with the superficial layer after 24-hour hypoxia (p < 0.05). Similar results were found when examining protein expression levels, with the deep ASCs expressing significantly larger amounts of VEGF-A and p-NF-κB (p < 0.05) compared with the superficial layer.

CONCLUSION

Our results suggest that significant variations exist in the angiogenic profile of superficial and deep ASCs. We demonstrate that superficial ASCs are less prone to transcribe potent chemokines for angiogenesis, such as VEGF-A, VEGF-B, and HIF-1α and are less likely to translate VEGF-A and NF-κB. This may help with the selection of specific stem cell donor sites in future models for stem cell therapy.

Motor unit changes seen with skeletal muscle sarcopenia in oldest old rats

Sarcopenia leads to many changes in skeletal muscle that contribute to atrophy, force deficits, and subsequent frailty. The purpose of this study was to characterize motor unit remodeling related to sarcopenia seen in extreme old age. Whole extensor digitorum longus muscle and motor unit contractile properties were measured in 19 adult (11-13 months) and 12 oldest old (36-37 months) Brown-Norway rats. Compared with adults, oldest old rats had significantly fewer motor units per muscle, smaller muscle cross-sectional area, and lower muscle specific force. However, mean motor unit force generation was similar between the two groups due to an increase in innervation ratio by the oldest old rats. These findings suggest that even in extreme old age both fast- and slow-twitch motor units maintain the ability to undergo motor unit remodeling that offsets some effects of sarcopenia.

Reconciling the effects of inflammatory cytokines on mesenchymal cell osteogenic differentiation

Therapies using mesenchymal stem cells are a popular current avenue for development and utilization, especially in the fields of de novo tissue engineering (Sanchez-Ramos J, Song S, Cardozo-Pelaez F, et al. Adult bone marrow stromal cells differentiate into neural cells in vitro. Exp Neurol 2000;164:247.) or tissue regeneration after physical injury (Kitoh H, Kitakoji T, Tsuchiya H, et al. Transplantation of marrow-derived mesenchymal stem cells and platelet-rich plasma during distraction osteogenesis-a preliminary result of three cases. Bone 2004;35:892; Shumakov VI, Onishchenko NA, Rasulov MF, Krasheninnikov ME, Zaidenov VA. Mesenchymal bone marrow stem cells more effectively stimulate regeneration of deep burn wounds than embryonic fibroblasts. Bull Exp Biol Med 2003;136:192; Bruder SP, Fink DJ, Caplan AI. Mesenchymal stem cells in bone development, bone repair, and skeletal regeneration therapy. J Cell Biochem 1994;56:283.). The osteogenic potential of these cells is of particular interest, given their recent usage for the closure of critical-sized bone defects and other nonhealing bone scenarios such as a nonunion. Recent literature suggests that inflammatory cytokines can significantly impact the osteogenic potential of these cells. A review of relevant, recent literature is presented regarding the impact of the inflammatory cascade on the osteogenic differentiation of these cells and how this varies across species. Finally, we identify areas of conflicting or absent evidence regarding the behavior of mesenchymal stem cells in response to inflammatory cytokines.

Early detection of burn induced heterotopic ossification using transcutaneous Raman spectroscopy

INTRODUCTION

Heterotopic ossification (HO), or the abnormal formation of bone in soft tissue, occurs in over 60% of major burn injuries and blast traumas. A significant need exists to improve the current diagnostic modalities for HO which are inadequate to diagnose and intervene on HO at early time-points. Raman spectroscopy has been used in previous studies to report on changes in bone composition during bone development but has not yet been applied to burn induced HO. In this study, we validate transcutaneous, in-vivo Raman spectroscopy as a methodology for early diagnosis of HO in mice following a burn injury.

METHODS

An Achilles tenotomy model was used to study HO formation. Following tenotomy, mice were divided into burn and sham groups with exposure of 30% surface area on the dorsum to 60° water or 30° water for 18s respectively. In-vivo, transcutaneous Raman spectroscopy was performed at early time points (5 days, 2 and 3 weeks) and a late time point (3 months) on both the tenotomized and non-injured leg. These same samples were then dissected down to the bone and ex-vivo Raman measurements were performed on the excised tissue. Bone formation was verified with Micro CT and histology at corresponding time-points.

RESULTS

Our Raman probe allowed non-invasive, transcutaneous evaluation of heterotopic bone formation. Raman data showed significantly increased bone mineral signaling in the tenotomy compared to control leg at 5 days post injury, with the difference increasing over time whereas Micro CT did not demonstrate heterotopic bone until three weeks. Ex-vivo Raman measurements showed significant differences in the amount of HO in the burn compared to sham groups and also showed differences in the spectra of new, ectopic bone compared to pre-existing cortical bone.

CONCLUSIONS

Burn injury increases the likelihood of developing HO when combined with traumatic injury. In our in-vivo mouse model, Raman spectroscopy allowed for detection of HO formation as early as 5 days post injury. Changes in bone mineral and matrix composition of the new bone were also evidenced in the Raman spectra which could facilitate early identification of HO and allow more timely therapy decisions for HO patients.

Hybrid conducting polymer-hydrogel conduits for axonal growth and neural tissue engineering

Successfully and efficiently bridging peripheral nerve gaps without the use of autografts is a substantial clinical advance for peripheral nerve reconstructions. Novel templating methods for the fabrication of conductive hydrogel guidance channels for axonal regeneration are designed and developed. PEDOT is electrodeposited inside the lumen to create fully coated-PEDOT agarose conduits and partially coated-PEDOT agarose conduits.

Effects of high- and low-velocity resistance training on the contractile properties of skeletal muscle fibers from young and older humans

A two-arm, prospective, randomized, controlled trial study was conducted to investigate the effects of movement velocity during progressive resistance training (PRT) on the size and contractile properties of individual fibers from human vastus lateralis muscles. The effects of age and sex were examined by a design that included 63 subjects organized into four groups: young (20-30 yr) men and women, and older (65-80 yr) men and women. In each group, one-half of the subjects underwent a traditional PRT protocol that involved shortening contractions at low velocities against high loads, while the other half performed a modified PRT protocol that involved contractions at 3.5 times higher velocity against reduced loads. Muscles were sampled by needle biopsy before and after the 14-wk PRT program, and functional tests were performed on permeabilized individual fiber segments isolated from the biopsies. We tested the hypothesis that, compared with low-velocity PRT, high-velocity PRT results in a greater increase in the cross-sectional area, force, and power of type 2 fibers. Both types of PRT increased the cross-sectional area, force, and power of type 2 fibers by 8-12%, independent of the sex or age of the subject. Contrary to our hypothesis, the velocity at which the PRT was performed did not affect the fiber-level outcomes substantially. We conclude that, compared with low-velocity PRT, resistance training performed at velocities up to 3.5 times higher against reduced loads is equally effective for eliciting an adaptive response in type 2 fibers from human skeletal muscle.

The effect of increased hip flexion using stirrups on lower-extremity venous flow: a prospective observational study

BACKGROUND

Patient positioning during surgeries for colorectal cancer may represent an unrecognized risk factor for deep venous thrombosis.

METHODS

Twelve healthy control patients were positioned supine with knee flexion at 90°. Duplex ultrasound examined common femoral vein (CFV) and proximal femoral vein diameter, peak systolic velocity, and volume flow with hip flexion at 0°, 30°, 60°, and 90°. Data were analyzed using the paired t test.

RESULTS

In the CFV, hip flexion to 90° was associated with a significant increase in mean volume flow when compared with hip flexion at 0° (.59 vs .36 L/min; P = .05) and 30° (.59 vs .35 L/min; P = .038). In both the CFV and proximal femoral vein, increased hip flexion was associated with significantly reduced vessel diameter and increased peak systolic velocity.

CONCLUSIONS

Intraoperative positioning of the lower extremities represents a modifiable risk factor for deep venous thrombosis. When stirrups are used, hip flexion of 90° maximizes venous drainage from the legs.

Early fasciotomy in electrically injured patients as a marker for injury severity and deep venous thrombosis risk: an analysis of the National Burn Repository

By using the National Burn Repository, the authors sought to identify markers for injury severity and deep venous thrombosis (DVT) risk after electrical injury. They identified adult patients in the National Burn Repository who were admitted with an electrical injury between 1995 and 2007 (n = 1469). Patients who died within 24 hours or were admitted for less than 1 day and hospitals reporting no complications were excluded. Independent variables included TBSA burned, duration of intensive care unit stay and hospital admission, duration of mechanical ventilation, the number of operative procedures, amputation, and early fasciotomy. Early fasciotomy was defined as fasciotomy performed on a patient's first trip to the operating room and was used as a proxy for severity of electrical injury. DVT and death were the dependent variables. Among electrically injured patients, 10.4% had early fasciotomy. Patients who had early fasciotomy had significantly prolonged intensive care unit stays (10.3 vs 4.8 days, P < .001), hospital days (36.7 vs 17.1 days, P < .001), amputations (49.0 vs 4.6%, P < .001), and a number of operative codes (17.6 vs 5.4, P < .001). DVT incidence was 0.9%. Electrically injured patients who had early fasciotomy were significantly more likely to have a DVT when compared with patients who did not have early fasciotomy (7.55 vs 0.95%, P = .002). Early fasciotomy after electrical injury is a marker for increased injury severity. Among patients who underwent early fasciotomy after electrical injury, 7.5% develop DVT, and 49% require amputation during their initial hospitalization.

Laparoscopic simulation training with proficiency targets improves practice and performance of novice surgeons

BACKGROUND

This study compares a laparoscopic skill training protocol without proficiency targets to the same protocol with explicit targets and notification of progress.

METHODS

Fourteen surgery interns were randomized into 2 groups. The intervention group received task-specific proficiency criteria to guide practice. The control group did not. After training, participants were evaluated by blinded faculty during laparoscopic cholecystectomy.

RESULTS

The control group met significantly fewer of the 7 LapSim (Surgical Science Sweden AB, Gotëborg) targets (mean = 1.14) than the intervention group (mean = 7.00; P = .001) and significantly fewer of the 5 video trainer targets (mean = .86) than the intervention group (mean = 5.00; P = .001). Ratings of depth perception, bimanual dexterity, efficiency, tissue handling, autonomy, and overall competence were higher for the intervention group. Effect sizes ranged from medium to large (.394-.981), indicating an impact of the proficiency-based training protocol.

CONCLUSIONS

Delineation of proficiency targets with reporting of progress improves interns' practice results, and appears to have a positive effect on their early operating room (OR) performance of laparoscopic cholecystectomy.

Conduction Properties Of Decellularized Nerve Biomaterials

The purpose of this study is to optimize poly(3,4,-ethylenedioxythiophene) (PEDOT) polymerization into decellular nerve scaffolding for interfacing to peripheral nerves. Our ultimate aim is to permanently implant highly conductive peripheral nerve interfaces between amputee, stump, nerve fascicles and prosthetic electronics. Decellular nerve (DN) scaffolds are an FDA approved biomaterial (Axogen ) with the flexible tensile properties needed for successful permanent coaptation to peripheral nerves. Biocompatible, electroconductive, PEDOT facilitates electrical conduction through PEDOT coated acellular muscle. New electrochemical methods were used to polymerize various PEDOT concentrations into DN scaffolds without the need for a final dehydration step. DN scaffolds were then tested for electrical impedance and charge density. PEDOT coated DN scaffold materials were also implanted as 15-20mm peripheral nerve grafts. Measurement of in-situ nerve conduction immediately followed grafting. DN showed significant improvements in impedance for dehydrated and hydrated, DN, polymerized with moderate and low PEDOT concentrations when they were compared with DN alone (a ≤ 0.05). These measurements were equivalent to those for DN with maximal PEDOT concentrations. In-situ, nerve conduction measurements demonstrated that DN alone is a poor electro-conductor while the addition of PEDOT allows DN scaffold grafts to compare favorably with the "gold standard", autograft (Table 1). Surgical handling characteristics for conductive hydrated PEDOT DN scaffolds were rated 3 (pliable) while the dehydrated models were rated 1 (very stiff) when compared with autograft ratings of 4 (normal). Low concentrations of PEDOT on DN scaffolds provided significant increases in electro active properties which were comparable to the densest PEDOT coatings. DN pliability was closely maintained by continued hydration during PEDOT electrochemical polymerization without compromising electroconductivity.

Early, staged reconstruction in young women with severe breast asymmetry

STUDY OBJECTIVE

To retrospectively examine a cohort of young women with severe hypoplasia or asymmetric breast development who underwent breast reconstruction with tissue expansion and to determine complication rates as well as patient satisfaction.

DESIGN

Chart review.

SETTING

The University of Michigan Hospital, a tertiary care center.

PARTICIPANTS

Women less than 25 years of age who underwent staged breast reconstruction with a tissue expander between 1998 and 2006.

MAIN OUTCOME MEASURES

Complication rate and patient satisfaction.

RESULTS

The mean age of patients undergoing the procedure was 18.1 years (range 14-25 years). Of 10 patients with recorded tobacco use, 8 (80%) were noted to be nonsmokers. One of 14 patients (7.1%) was found to have a minor complication (cellulitis), and 2 of 14 (14.2%) were found to have major complications. Of the 13 patients who had at least 6 weeks of follow-up after completion of their reconstruction, 10 were subjectively documented as pleased with the result, 2 records made no mention of patient satisfaction, and 1 patient had concerns regarding her results.

CONCLUSION

Our study shows promising results for the use of tissue expanders in young women with significant breast asymmetry or unilateral/bilateral micromastia. The very important issues of short-term and long-term satisfaction and outcomes needs further study before advocating an early approach to teens with breast deformities.

Optimizing skeletal muscle reinnervation with nerve transfer

Denervation as a consequence of nerve injury causes profound structural and functional changes within skeletal muscle and can lead to a marked impairment in function of the affected limb. Prompt reinnervation of a muscle with a sufficient number of motion-specific motor axons generally results in good structural and functional recovery, whereas long-term denervation or insufficient or improper axonal recruitment uniformly results in poor functional recovery. Only nerve transfer has been highly efficacious in changing the clinical outcomes of patients with skeletal muscle denervation, especially in the case of proximal limb nerve injuries. Rapid reinnervation with an abundant number of motor axons remains the only clinically effective means to restore function to denervated skeletal muscles.

Effect of cleft palate repair on the susceptibility to contraction-induced injury of single permeabilized muscle fibers from congenitally-clefted goat palates

OBJECTIVE

Despite cleft palate repair, velopharyngeal competence is not achieved in approximately 15% of patients, often necessitating secondary surgical correction. Velopharyngeal competence postrepair may require the conversion of levator veli palatini muscle fibers from injury-susceptible type 2 fibers to injury-resistant type 1 fibers. As an initial step to determining the validity of this theory, we tested the hypothesis that, in most cases, repair induces the transformation to type 1 fibers, thus diminishing susceptibility to injury.

INTERVENTIONS

Single permeabilized levator veli palatini muscle fibers were obtained from normal palates and nonrepaired congenitally-clefted palates of young (2 months old) and adult (14 to 15 months old) goats and from repaired palates of adult goats (8 months old). Repair was done at 2 months of age using a modified von Langenbeck technique.

MAIN OUTCOME MEASURES

Fiber type was determined by contractile properties and susceptibility to injury was assessed by force deficit, the decrease in maximum force following a lengthening contraction protocol expressed as a percentage of initial force.

RESULTS

For normal palates and cleft palates of young goats, the majority of the fibers were type 2 with force deficits of approximately 40%. Following repair, 80% of the fibers were type 1 with force deficits of 20% +/- 2%; these deficits were 45% of those for nonrepaired cleft palates of adult goats (p < .0001).

CONCLUSION

The decrease in the percentage of type 2 fibers and susceptibility to injury may be important for the development of a functional levator veli palatini muscle postrepair.

Outcomes of surgical management of stage III vulvar hidradenitis suppurativa

OBJECTIVE

To review prior experiences and outcomes of patients treated for stage III vulvar hidradenitis suppurativa (HS) and determine postoperative patient satisfaction.

STUDY DESIGN

Patients managed surgically for stage III vulvar HS at University of Michigan Health Systems (January 2000 to December 2005) were identified. Retrospective record review was undertaken and data collected. Five met study criteria. All underwent radical vulvectomy to excise the HS. Most required extensive excision of the vulva, including mons, perianal area and buttock. One surgical defect was allowed to heal by secondary intention; all others underwent interval closure with split-thickness skin grafting (STSG). After debridement, all wounds were dressed with a vacuum assisted closure device.

RESULTS

Of the 5 patients, 4 were satisfied with their outcome. The patient managed without STSG developed an introital stricture and was the only patient regretting undergoing surgical excision of the hidradenitis suppurativa. Some amount of depression was present in all patients postoperatively. Four were happy with the surgery; 3 said they would undergo surgery again.

CONCLUSION

Patients with severe HS often require radical excision. Data conflict regarding optimal surgical management. Our experience supports good outcome in patients managed with radical excision and STSG.