Purification and characterization of an inhibitor (soluble tumor necrosis factor receptor) for tumor necrosis factor and lymphotoxin obtained from the serum ultrafiltrates of human cancer patients

Serum ultrafiltrates (SUF) from human patients with different types of cancer contain a blocking factor (BF) that inhibits the cytolytic activity of human tumor necrosis factor alpha (TNF-alpha) in vitro. BF is a protein with a molecular mass of 28 kDa on reducing sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS/PAGE). The active material was purified to homogeneity by a combination of affinity chromatography, PAGE, and high-pressure liquid chromatography. Amino acid sequence analysis revealed that BF is derived from the membrane TNF receptor. Purified BF blocks the lytic activity of recombinant human and mouse TNF-alpha and recombinant human lymphotoxin on murine L929 cells in vitro. However, BF inhibits the lytic activity of TNF-alpha more effectively than it does that of lymphotoxin. The BF also inhibits the necrotizing activity of recombinant human TNF-alpha when coinjected into established cutaneous Meth A tumors in BALB/c mice. The BF may have an important role in (i) the regulation and control of TNF-alpha and lymphotoxin activity in cancer patients, (ii) interaction between the tumor and the host antitumor mechanisms, and (iii) use of systemically administered TNF-alpha in clinical trials with human cancer patients.

Contemporary perspectives on heterotopic ossification

Heterotopic ossification (HO) is the formation of ectopic bone that is primarily genetically driven (fibrodysplasia ossificans progressiva [FOP]) or acquired in the setting of trauma (tHO). HO has undergone intense investigation, especially over the last 50 years, as awareness has increased around improving clinical technologies and incidence, such as with ongoing wartime conflicts. Current treatments for tHO and FOP remain prophylactic and include NSAIDs and glucocorticoids, respectively, whereas other proposed therapeutic modalities exhibit prohibitive risk profiles. Contemporary studies have elucidated mechanisms behind tHO and FOP and have described new distinct niches independent of inflammation that regulate ectopic bone formation. These investigations have propagated a paradigm shift in the approach to treatment and management of a historically difficult surgical problem, with ongoing clinical trials and promising new targets.

The regulation of TNF receptor mRNA synthesis, membrane expression, and release by PMA- and LPS-stimulated human monocytic THP-1 cells in vitro

The regulation of the 55-kDa TNF receptor (TNF-R) mRNA synthesis, membrane expression, and TNF binding factor (BF) release was examined in resting and activated human monocytic THP-1 and human promyelocytic leukemia HL-60 cells in vitro. Cells were activated with phorbol myristate acetate (PMA) and bacterial lipopolysaccharide (LPS). TNF alpha cytolytic activity in the supernatant of THP-1 cells stimulated by PMA began to appear at 4 hr, reached a peak at 8 hr, and declined by 12 hr. For THP-1 cells stimulated with LPS, the peak of TNF alpha activity appeared at 4 hr and then declined. TNF alpha-binding sites on the cell membrane were down-regulated within 1 hr after PMA and LPS treatment and then reappeared 12 hr later. Fifty-five-kilodalton TNF-R mRNA expression during this time period did not correlate with the level of membrane TNF-binding site expression. Additional studies indicated the presence of a 30-kDa TNF-BF in the supernatants which appeared after 24 hr. These data suggest that activated THP-1 and HL-60 cells are capable of releasing TNF-BF into the supernatant and this material may be involved in the control of secreted TNF alpha activities.

A 20 amino acid synthetic peptide of a region from the 55 kDa human TNF receptor inhibits cytolytic and binding activities of recombinant human tumour necrosis factor in vitro

Tumour Necrosis Factor (TNF) and Lymphotoxin (LT) can exert a wide range of effects on cells and tissues and they are important effector molecules in cell mediated immunity. All these effects are induced subsequent to the binding of these cytokines to specific membrane receptors. Recently, two of these membrane receptors of 55 and 75 kDa, have been identified which share some amino acid (AA) homology in their N-terminal extracellular domains but differ in their intracellular domains. We synthesized two synthetic 20 AA peptides from hydrophilic regions of the N-terminal extracellular domains of the 55 kDa receptor; peptide A shares homology with both 55 and 75 kDa receptors, peptide B is unique. We found peptide B inhibits both the binding and cytolytic activity of recombinant human TNF when tested on murine L929 cells in vitro. Polyclonal antiserum generated against peptide B will block binding of 125I-labelled TNF to these cells in vitro. However, peptide A and antiserum prepared against peptide A are without effect in these same assay systems. These data suggest that the 20 AA sequences from AA 175 to 194 in the N-terminal extracellular domain of the 55 kDa TNF receptor are expressed on the cell surface and are involved in the binding of TNF.

Macrophage TGFβ signaling is critical for wound healing with heterotopic ossification after trauma

Transforming growth factor beta 1 (TGFβ1) plays a central role in normal and aberrant wound healing, but the precise mechanism in the local environment remains elusive. Here, using a mouse model of aberrant wound healing resulting in heterotopic ossification (HO) after traumatic injury, we find autocrine TGFβ1 signaling in macrophages, and not mesenchymal stem/progenitor cells (MPCs), is critical in HO formation. In-depth single cell transcriptomic and epigenomic analyses in combination with immunostaining of cells from the injury site demonstrate increased TGFβ1 signaling in early infiltrating macrophages, with open chromatin regions in TGFβ1 stimulated genes at binding sites specific for transcription factors of activated TGFβ1 (SMAD2/3). Genetic deletion of TGFβ1 receptor type 1, (Tgfbr1;Alk5) in macrophages, results in increased HO, with a trend toward decreased tendinous HO. To bypass the effect seen by altering the receptor we administered a systemic treatment with TGFβ1/3 ligand trap TGFβRII-Fc, which results in decreased HO formation and a delay macrophage infiltration to the injury site. Overall, our data support the role of the TGFβ1/ALK5 signaling pathway in HO.

VEGFA Promotes Skeletal Muscle Regeneration in Aging

Aging is associated with loss of skeletal muscle regeneration. Differentially regulated vascular endothelial growth factor (VEGF)A with aging may partially underlies this loss of regenerative capacity. To assess the role of VEGFA in muscle regeneration, young (12-14 weeks old) and old C57BL/6 mice (24,25 months old) are subjected to cryoinjury in the tibialis anterior (TA) muscle to induce muscle regeneration. The average cross-sectional area (CSA) of regenerating myofibers is 33% smaller in old as compared to young (p < 0.01) mice, which correlates with a two-fold loss of muscle VEGFA protein levels (p = 0.02). The capillary density in the TA is similar between the two groups. Young VEGFlo mice, with a 50% decrease in systemic VEGFA activity, exhibit a two-fold reduction in the average regenerating fiber CSA following cryoinjury (p < 0.01) in comparison to littermate controls. ML228, a hypoxia signaling activator known to increase VEGFA levels, augments muscle VEGFA levels and increases average CSA of regenerating fibers in both old mice (25% increase, p < 0.01) and VEGFlo (20% increase, p < 0.01) mice, but not in young or littermate controls. These results suggest that VEGFA may be a therapeutic target in age-related muscle loss.

Short-wave infrared light imaging measures tissue moisture and distinguishes superficial from deep burns

Existing clinical approaches and tools to measure burn tissue destruction are limited resulting in misdiagnosis of injury depth in over 40% of cases. Thus, our objective in this study was to characterize the ability of short-wave infrared (SWIR) imaging to detect moisture levels as a surrogate for tissue viability with resolution to differentiate between burns of various depths. To accomplish our aim, we constructed an imaging system consisting of a broad-band Tungsten light source; 1,200-, 1,650-, 1,940-, and 2,250-nm wavelength filters; and a specialized SWIR camera. We initially used agar slabs to provide a baseline spectrum for SWIR light imaging and demonstrated the differential absorbance at the multiple wavelengths, with 1,940 nm being the highest absorbed wavelength. These spectral bands were then demonstrated to detect levels of moisture in inorganic and in vivo mice models. The multiwavelength SWIR imaging approach was used to diagnose depth of burns using an in vivo porcine burn model. Healthy and injured skin regions were imaged 72 hours after short (20 seconds) and long (60 seconds) burn application, and biopsies were extracted from those regions for histologic analysis. Burn depth analysis based on collagen coagulation histology confirmed the formation of superficial and deep burns. SWIR multispectral reflectance imaging showed enhanced intensity levels in long burned regions, which correlated with histology and distinguished between superficial and deep burns. This SWIR imaging method represents a novel, real-time method to objectively distinguishing superficial from deep burns.

"Development of an Academic Surgical Student Program for Enhancing Student-Faculty Engagement"

OBJECTIVE

We describe an innovative medical student surgery interest group and its influence on mentorship and career exploration.

DESIGN

SCRUBS, created to promote interest in academic surgery, is student-led, with continual surgical faculty and resident involvement. Its 3-component programming focuses on clinical skills, research, and mentorship opportunities for medical students to get involved in academic surgery early in medical education.

SETTING

The University of Michigan Medical School, Ann Arbor, MI.

PARTICIPANTS

First through fourth year medical students, surgery residents, and attending surgeons.

RESULTS

SCRUBS is a multifaceted student organization providing longitudinal exposure to various aspects of surgery and academic medicine. The group grew annually from 2010 to 2014, with students and faculty expressing positive feedback. Over the time period reviewed, we had a greater percentage of students applying into surgical specialties compared with the national average (16.8 vs 12% in 2014). The group supported and facilitated mentorship, clinical skills development, and research opportunities for interested students.

CONCLUSIONS

This innovative surgery interest group has been well received by students and surgeons, and our institution has seen above-average interest in surgical careers. Early, preclinical mentorship and exposure provided by SCRUBS may contribute to this higher surgical interest.

Reduction Mammaplasty in Younger Patients: An Evidence-Based Approach to Treatment

Macromastia is a common condition that can lead to physical pain, emotional burden, and behavioral impairment, with significant decrements in quality of life. Reduction mammaplasty offers the only effective treatment of symptomatic macromastia, and patients experience significant improvements in their physical and psychosocial health through surgical correction. Although symptoms typically arise during adolescence, most women seeking surgical intervention do not undergo reduction mammaplasty until their fifth decade of life. Providers often delay surgery due to speculative concerns about emotional immaturity, postoperative breast regrowth, and future lactation performance. The strict guidelines related to age and body mass index imposed by insurance companies further restrict the options available to younger patients with macromastia. This review offers an evidence-based approach to treating macromastia in younger patients. After more than 15 years of treatment and research centered on adolescents and young adults with macromastia led by the senior author (B.I.L.), a pediatric plastic surgeon, we have found that reduction mammaplasty is a safe and effective treatment option for this patient population. It is our hope that our work will enable care providers to make data-supported decisions when treating younger patients with symptomatic macromastia.

Pain Remission Following Delayed Targeted Muscle Reinnervation in Amputees

INTRODUCTION

Targeted muscle reinnervation (TMR) has demonstrated efficacy for treatment of neuropathic pain. This study aims to identify patients for whom delayed TMR may be most effective and to identify associated factors for favorable pain outcomes in this patient population.

METHODS

An analysis was conducted on prospectively enrolled amputee patients who underwent delayed TMR at a tertiary care center from 2017 to 2024. Data on demographics, comorbidities, surgical details, and pain outcomes were collected. Patient reported pain severity on a 0-10 scale was prospectively collected. The main pain outcome was pain remission (achieving the minimally clinically important difference (MCID)). Additionally, sustained mild pain (pain score ≤ 3/10 for ≥ 3 months), and pain disappearance (pain score 0/10 for ≥ 3 months) were assessed. Multivariable regression analyses identified factors influencing pain outcomes.

RESULTS

Out of 101 patients included in this study, 64 patients (63.4%) achieved pain remission within a two-year post-operative period, and 37 patients (36.6%) did not. Sustained mild pain, which could be achieved in addition to pain remission, was achieved by 45.8% of patients, with 17.8% of these achieving complete pain disappearance. Patients achieving pain remission demonstrated lower pain over the entire post-operative trajectory (p < 0.001). Lower pre-operative pain scores, absence of depression, no pre-operative opioid use, lower Elixhauser Comorbidity Index, and distal amputation levels were correlated with favorable outcomes following delayed TMR (p < 0.05).

DISCUSSION

Pre-operative pain severity, psychiatric comorbidities, and opioid use significantly influenced pain outcomes, emphasizing the need for comprehensive patient assessment. These findings will help with patient stratification and pre-operative counseling to support patients who are best suitable for delayed TMR surgery.

The neuroma map: A systematic review of the anatomic distribution, etiologies, and surgical treatment of painful traumatic neuromas

BACKGROUND

This study analyzed all reported cases of painful traumatic neuromas to better understand their anatomic distribution, etiologies, and surgical treatment.

METHODS

PubMed, Embase, Cochrane, and Web of Science were searched in October 2023 for articles describing painful traumatic neuromas.

RESULTS

In total, 414 articles reporting 5,562 neuromas were included and categorized into head/neck, trunk, upper extremity, lower extremity, and autonomic nerves. Distribution was as follows: Head/neck: 83 articles reported on 393 neuromas (93.2% iatrogenic) most frequently involving the lingual (44.4%), cervical plexus (15.0%), great auricular (8.6%), inferior/superior alveolar (8.3%), and occipital (7.2%) nerves. Trunk: 47 articles reported on 552 neuromas (92.9% iatrogenic) most commonly involving the intercostal (40.0%), ilioinguinal (18.2%) and genitofemoral (16.2%) nerves. Upper extremity: 160 articles reported on 2082 neuromas (42.2% after amputation) most frequently involving the digital (47.0%), superficial radial (18.3%), and median (7.0%) nerves. Lower extremity: 128 articles reported on 2,531 neuromas (53.0% after amputation) most commonly involving the sural (17.9%), superficial peroneal (17.3%), and saphenous (16.0%) nerves. Autonomic nerves: 17 articles reported on 53 neuromas (100% iatrogenic) most frequently involving the biliary tract (64.2%) and vagus nerve (18.9%). Compared with the extremities, neuromas in the head/neck and trunk had significantly longer symptom duration before surgical treatment and the nerve end was significantly less frequently reconstructed after neuroma excision.

CONCLUSION

Painful neuromas are predominantly reported in the extremities yet may occur throughout the body primarily after iatrogenic injury. Knowledge of their anatomic distribution from head to toe will encourage awareness to avoid injury and expedite diagnosis to prevent treatment delay.

Posttraumatic Penile Replantation with Minimal Skin Necrosis

Penile amputation is a surgical emergency where practical and timely perioperative management is crucial for ensuring a successful outcome. Tenuous viability of penile and scrotal skin has been well described in the literature, with a putative mechanism attributed to the transection of distal branches of the external pudendal artery. Although the perforasomes critical to penile replantation have been debated, this case report details a patient who successfully recovered sensation and function with minimal necrosis after penile replantation. Surgically, this was facilitated by intentional drain placement, aggressive debridement beyond the zone of injury, and planned redundancies with dorsal artery/vein anastomoses via interposition grafts of the dorsal penile vessels alone.

Predictive Value of Preoperative Pain Sketches in Lower Extremity Amputees Undergoing Secondary Targeted Muscle Reinnervation for Treatment of Neuropathic Pain

BACKGROUND

Targeted muscle reinnervation (TMR) is an effective surgical treatment for neuropathic pain in amputees. Qualitative descriptions of pain, depicted by pain sketches, could enhance the understanding of symptomatic improvement after surgery. Our aim is to assess whether preoperative pain sketches, drawn by lower extremity (LE) amputees, can predict surgical outcomes after secondary TMR surgery.

STUDY DESIGN

Eligible patients were LE amputees who underwent secondary TMR surgery between 2017 and 2023. Pain sketches and pain scores were prospectively collected both before and after surgery. The pain trajectory, as categorized by preoperative pain sketches, was analyzed and assessed for improvement, defined as reaching the minimal clinically important difference. The transition into different pain sketches and the occurrence of phantom drawings were evaluated for their association with improvement.

RESULTS

Fifty-eight patients were included, of which 18 (31.1%) depicted diffuse pain, 26 (44.8%) depicted focal pain (FP), and 18 (24.1%) depicted radiating pain (RP) in their preoperative sketch. FP sketches were associated with the lowest pre- and postoperative pain scores and most frequently developed into sketches indicating "no pain." RP sketches were associated with the least pain improvement, the lowest likelihood of achieving the minimal clinically important difference, and were more prevalent in patients with diabetes or depression. RP sketches were associated with phantom drawings; no other sketch types developed into RP sketches at the final follow-up.

CONCLUSIONS

In LE amputees who underwent secondary TMR, preoperative pain sketches could serve as a helpful tool in predicting pain outcomes. RP sketches seemed to be associated with worse outcomes and FP sketches with the most improvement.

Neuroma morphology: A macroscopic classification system

INTRODUCTION/AIMS

Neuromas come in different shapes and sizes; yet the correlation between neuroma morphology and symptomatology is unknown. Therefore, we aim to investigate macroscopic traits of excised human neuromas and assess the validity of a morphological classification system and its potential clinical implications.

METHODS

End-neuroma specimens were collected from prospectively enrolled patients undergoing symptomatic neuroma surgery. Protocolized images of the specimens were obtained intraoperatively. Pain data (Numeric rating scale, 0-10) were prospectively collected during preoperative interview, patient demographic and comorbidity factors were collected from chart review. A morphological classification is proposed, and the inter-rater reliability (IRR) was assessed. Distribution of neuroma morphology with patient factors, was described.

RESULTS

Forty-five terminal neuroma specimens from 27 patients were included. Residual limb patients comprised 93% of the population, of which 2 were upper (8.0%) and 23 (92.0%) were lower extremity residual limb patients. The proposed morphological classification, consisting of three groups (bulbous, fusiform, atypical), demonstrated a strong IRR (Cohen's kappa = 0.8). Atypical neuromas demonstrated higher preoperative pain, compared with bulbous and fusiform. Atypical morphology was more prevalent in patients with diabetes and peripheral vascular disease.

DISCUSSION

A validated morphological classification of neuroma is introduced. These findings may assist surgeons and researchers with better understanding of symptomatic neuroma development and their clinical implications. The potential relationship of neuroma morphology with the vascular and metabolic microenvironment requires further investigation.

The Use of Nerve Caps after Nerve Transection in Headache Surgery: Cadaver and Case Reports

Background

Nerve transection with nerve reconstruction is part of the treatment algorithm for patients with refractory pain after greater occipital nerve (GON) and lesser occipital nerve (LON) decompression or during primary decompression when severe nerve injury or neuroma formation is present. Importantly, the residual nerve stump is often best addressed via contemporary nerve reconstruction techniques to avoid recurrent pain. As a primary aim of this study, nerve capping is explored as a potential viable alternative that can be utilized in certain headache cases to mitigate pain.

Methods

The technical feasibility of nerve capping after GON/LON transection was evaluated in cadaver dissections and intraoperatively. Patient-reported outcomes in the 3- to 4-month period were compiled from clinic visits. At 1-year follow-up, subjective outcomes and Migraine Headache Index scores were tabulated.

Results

Two patients underwent nerve capping as a treatment for headaches refractory to medical therapy and surgical decompressions with significant improvement to total resolution of pain without postoperative complications. These improvements on pain frequency, intensity, and duration remained stable at a 1-year time point (Migraine Headache Index score reductions of -180 to -205).

Conclusions

Surgeons should be equipped to address the proximal nerve stump to prevent neuroma and neuropathic pain recurrence. Next to known contemporary nerve reconstruction techniques such as targeted muscle reinnervation/regenerative peripheral nerve interface and relocation nerve grafting, nerve capping is another viable method for surgeons to address the proximal nerve stump in settings of GON and LON pain. This option exhibits short operative time, requires only limited dissection, and yields significant clinical improvement in pain symptoms.

The influence of nerve surgical techniques at time of amputation on the prevalence of heterotopic ossification in transtibial amputees

BACKGROUND

Heterotopic ossification (HO) can form after amputation and may cause pain and functional impairment. We aimed to describe the prevalence of HO in a civilian population of transtibial amputees. We hypothesized that the decreased rate of symptomatic neuroma following active nerve surgery (Targeted Muscle Reinnervation (TMR) or Regenerative Peripheral Nerve Interface (RPNI)) may subsequently lead to a lower prevalence of HO compared to passive nerve surgery (i.e. traction neurectomy) performed at the time of amputation.

METHODS

Adult patients undergoing transtibial amputation at a tertiary care center between 2000 and 2023 were included. Patient data were collected through chart review. The most recent post-amputation X-ray of the residual limb was assessed for HO presence, according to the Walter Reed classification. A random subset of X-rays (10.0 %) was independently assessed by five clinicians and two radiologists, and inter-rater reliability (IRR) was calculated using Cohen's kappa (κ). Multivariable logistic regression was conducted to identify factors associated with HO presence.

RESULTS

In total, 665 limbs of 632 patients were included. The median time between amputation and X-ray was 1.7 years (IQR: 0.3-6.2). HO was identified in 326 X-rays (49.0 %) and was commonly present on the distal residual tibia (68.1 %) and fibula (69.0 %). Traditional amputations (i.e. those without TMR or RPNI (OR: 2.0, p = 0.014)), and the presence of a symptomatic neuroma (OR: 2.3, p < 0.001), were independently associated with a higher prevalence of HO. The IRR of the two radiologists was κ = 0.99, the overall IRR of all evaluators was κ = 0.92.

CONCLUSIONS

HO is a common finding in transtibial amputees. Peripheral nerve surgerical techniques that actively address amputated nerve endings to reduce symptomatic neuroma formation may decrease the prevalence of HO.

Neuroma-to-Nerve Ratio: Does Size Matter?

BACKGROUND AND OBJECTIVES

Anatomic features of neuromas have been explored in imaging studies. However, there has been limited research into these features using resected, ex vivo human neuroma specimens. The aim of this study was to investigate the influence that time may have on neuroma growth and size, and the clinical significance of these parameters.

METHODS

Patients who underwent neuroma excision between 2022 through 2023 were prospectively included in this study. Neuroma specimens were obtained after operative resection. Standardized neuroma size measurements, expressed as a neuroma-to-nerve ratio (NNR), were conducted with ImageJ software. Pain data (numeric rating scale, 0-10) were prospectively recorded during preoperative evaluation, and patient factors were collected from chart reviews.

RESULTS

Fifty terminal neuroma specimens from 31 patients were included, with 94.0% of the neuromas obtained from individuals with amputations. Most neuromas were excised from the lower extremities (n = 44, 88.0%). The neuromas had a median NNR of 2.45, and the median injury to neuroma excision interval was 6.3 years. Larger NNRs were associated with a longer injury to neuroma excision interval and with a smaller native nerve diameter. In addition, sensory nerves were associated with a larger NNR compared with mixed nerves. NNR was not associated with preoperative pain or with anatomical nerve distribution.

CONCLUSION

This study suggests that neuromas seem to continue to grow over time and that smaller nerves may form relatively larger neuromas. In addition, sensory nerves develop relatively larger neuromas compared with mixed nerves. Neuroma size does not appear to correlate with pain severity. These findings may stimulate future research efforts and contribute to a better understanding of symptomatic neuroma development.

Biology and pathophysiology of symptomatic neuromas

ABSTRACT

Neuromas are a substantial cause of morbidity and reduction in quality of life. This is not only caused by a disruption in motor and sensory function from the underlying nerve injury but also by the debilitating effects of neuropathic pain resulting from symptomatic neuromas. A wide range of surgical and therapeutic modalities have been introduced to mitigate this pain. Nevertheless, no single treatment option has been successful in completely resolving the associated constellation of symptoms. While certain novel surgical techniques have shown promising results in reducing neuroma-derived and phantom limb pain, their effectiveness and the exact mechanism behind their pain-relieving capacities have not yet been defined. Furthermore, surgery has inherent risks, may not be suitable for many patients, and may yet still fail to relieve pain. Therefore, there remains a great clinical need for additional therapeutic modalities to further improve treatment for patients with devastating injuries that lead to symptomatic neuromas. However, the molecular mechanisms and genetic contributions behind the regulatory programs that drive neuroma formation-as well as the resulting neuropathic pain-remain incompletely understood. Here, we review the histopathological features of symptomatic neuromas, our current understanding of the mechanisms that favor neuroma formation, and the putative contributory signals and regulatory programs that facilitate somatic pain, including neurotrophic factors, neuroinflammatory peptides, cytokines, along with transient receptor potential, and ionotropic channels that suggest possible approaches and innovations to identify novel clinical therapeutics.