RESUMEN
PURPOSE: The flexor digitorum superficialis (FDS) tendon transfer can be used to restore opposition of the thumb. Several pulley designs have been proposed for this transfer. Gliding resistance is considered to be an important factor influencing the efficiency of the pulley design. Our purpose was to compare the gliding resistance among 4 commonly used pulleys for the FDS oppositional transfer. METHODS: Ten fresh-frozen cadaver specimens were studied. The ring FDS was used as the donor tendon. An oppositional transfer was created using 4 pulley configurations: FDS passed around the flexor carpi ulnaris (a-FCU), FDS passed through a 2.5-cm circumference distally based FCU loop (2.5-FCU), FDS passed through a 3.5-cm circumference distally based FCU loop (3.5-FCU), and FDS passed through a longitudinal split in the FCU tendon (s-FCU). The gliding resistance was measured with the thumb in radial abduction and maximum opposition. RESULTS: In abduction, the average FDS gliding resistance of a-FCU, 2.5-FCU, 3.5-FCU, and s-FCU was 0.66 N (SD, 0.14 N), 0.70 N (SD, 0.14 N), 0.68 N (SD, 0.16 N), and 0.79 N (SD, 0.15 N), respectively. The peak gliding resistance of a-FCU, 2.5-FCU, 3.5-FCU, and s-FCU was 0.75 N (SD, 0.16 N), 0.74 N (SD, 0.15 N), 0.74 N (SD, 0.15 N), and 0.86 N (SD, 0.15 N), respectively. CONCLUSIONS: The average gliding resistance of the s-FCU was found to be significantly higher than that of the a-FCU and 3.5-FCU pulleys. In opposition, there were no differences in average or peak gliding resistance among the different pulley designs. CLINICAL RELEVANCE: In this in vitro cadaveric study, the FDS split pulley produced higher gliding resistance. Consideration of the pulley configuration may improve the overall thumb function by decreasing forces needed to overcome gliding resistance.
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Transferencia Tendinosa , Tendones , Humanos , Tendones/cirugía , Dedos , Músculo Esquelético , Pulgar/cirugía , Fenómenos BiomecánicosRESUMEN
Soft tissue defects are common following trauma and tumor extirpation. These injuries can result in poor functional recovery and lead to a diminished quality of life. The healing of skin and muscle is a complex process that, at present, leads to incomplete recovery and scarring. Regenerative medicine may offer the opportunity to improve the healing process and functional outcomes. Barriers to regenerative strategies have included cost, regulatory hurdles, and the need for cell-based therapies. In recent years, exosomes, or extracellular vesicles, have gained tremendous attention in the field of soft tissue repair and regeneration. These nanosized extracellular particles (30-140 nm) can break the cellular boundaries, as well as facilitate intracellular signal delivery in various regenerative physiologic and pathologic processes. Existing studies have established the potential of exosomes in regenerating tendons, skeletal muscles, and peripheral nerves through different mechanisms, including promoting myogenesis, increasing tenocyte differentiation and enhancing neurite outgrowth, and the proliferation of Schwann cells. These exosomes can be stored for immediate use in the operating room, and can be produced cost efficiently. In this article, we critically review the current advances of exosomes in soft tissue (tendons, skeletal muscles, and peripheral nerves) healing. Additionally, new directions for clinical applications in the future will be discussed.
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Exosomas , Vesículas Extracelulares , Calidad de Vida , Medicina Regenerativa , Células de SchwannRESUMEN
The intrinsic healing following tendon injury is ideal, in which tendon progenitor cells proliferate and migrate to the injury site to directly bridge or regenerate tendon tissue. However, the mechanism determining why and how those cells are attracted to the injury site for tendon healing is not understood. Since the tenocytes near the injury site go through apoptosis or necrosis following injury, we hypothesized that secretions from injured tenocytes might have biological effects on cell proliferation and migration to enhance tendon healing. Tenocyte apoptosis was induced by 24 h cell starvation. Apoptotic body-rich media (T-ABRM) and apoptotic body-depleted media (T-ABDM) were collected from culture media after centrifuging. Tenocytes and bone marrow-derived stem cells (BMDSCs) were isolated and cultured with the following four media: (1) T-ABRM, (2) T-ABDM, (3) GDF-5, or (4) basal medium with 2% fetal calf serum (FCS). The cell activities and functions were evaluated. Both T-ABRM and T-ABDM treatments significantly stimulated the cell proliferation, migration, and extracellular matrix synthesis for both tenocytes and BMDSCs compared to the control groups (GDF-5 and basal medium). However, cell proliferation, migration, and extracellular matrix production of T-ABRM-treated cells were significantly higher than the T-ABDM, which indicates the apoptotic bodies are critical for cell activities. Our study revealed the possible mechanism of the intrinsic healing of the tendon in which apoptotic bodies, in the process of apoptosis, following tendon injury promote tenocyte and stromal cell proliferation, migration, and production. Future studies should analyze the components of the apoptotic bodies that play this role, and, thus, the targeting of therapeutics can be developed.
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Vesículas Extracelulares , Células Madre Mesenquimatosas , Traumatismos de los Tendones , Proliferación Celular , Células Cultivadas , Medios de Cultivo/farmacología , Factor 5 de Diferenciación de Crecimiento/farmacología , Humanos , Células Madre Mesenquimatosas/fisiología , Albúmina Sérica Bovina/farmacología , Traumatismos de los Tendones/terapia , TenocitosRESUMEN
BACKGROUND: The purpose of this study was to determine the effect of fibrinogen concentration on cell viability and migration in a tissue culture tendon healing model. METHODS: Forty-eight canine flexor digitorum profundus tendons were randomly divided into three groups. In each group the tendons were lacerated and repaired augmented with a canine bone marrow stromal cell seeded fibrin interposition patch using either 5 mg/ml fibrinogen and 25 U/ml thrombin (physiological as a control), 40 mg/ml fibrinogen and 250 U/ml thrombin (low adhesive), or 80 mg/ml fibrinogen and 250 U/ml thrombin (high adhesive). The sutured tendons were cultured for two or four weeks. RESULTS: Failure load was not significantly different among the groups. Cell-labeling staining showed that the stromal cells migrated across the gap in the control and low adhesive groups, but there was no cell migration in the high adhesive group at two weeks. CONCLUSION: A high fibrinogen concentration in a fibrin patch or glue may impede early cell migration. LEVEL OF EVIDENCE: Not applicable because this study was a laboratory study.
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Procedimientos de Cirugía Plástica , Traumatismos de los Tendones , Animales , Perros , Movimiento Celular , Fibrina , Traumatismos de los Tendones/tratamiento farmacológico , Traumatismos de los Tendones/cirugía , Tendones/cirugíaRESUMEN
BACKGROUND: Carpal Tunnel Syndrome (CTS) is an idiopathic fibrotic disorder. Fibrosis in the subsynovial connective tissues (SSCT) of CTS and many other fibrotic diseases is mediated by Transforming growth factor ß (TGF-ß). Recently monocyte chemoattractant protein-1 (MCP-1) a cytokine involved in cellular recruitment has been suggested to regulate TGF-ß activity. It is related to the onset of diseases which are caused by fibrosis, such as idiopathic pulmonary fibrosis, renal fibrosis, and systemic scleroderma. In this study, we evaluated the effect of the MCP-1 synthesis inhibitor, Bindarit, on primary cultures of fibroblasts from the SSCT of five CTS patients. METHODS: Fibroblasts were treated with Bindarit (10 µM, 50 µM, 100 µM, or 300 µM). Responses to inhibitors were evaluated by regulation of CTS fibrosis-associated genes, fibrosis gene array and Smad luciferase reporter assay. We also assessed the combination effect of Bindarit and SD208, a TGF-ß receptor type 1 inhibitor on TGF-ß signaling. RESULTS: Collagen type III A1 (Col3), connective tissue growth factor (CTGF), and SERPINE1 expression were significantly down-regulated by Bindarit (300 µM) compared to vehicle control. In the fibrosis array, expression of inhibin beta E chain precursor (INHBE), beta actin (ACTB), endothelin 1 (EDN1) and hypoxanthine phosphoribosyltransferase 1 (HPRT1) were significantly down-regulated, and integrin beta-3 (ITGB3) was significantly up-regulated by Bindarit (300 µM). Smad signal transduction activation was significantly down-regulated by Bindarit (300 µM) and/or SD208 (1 µM) with TGF-ß1 compared to vehicle control with TGF-ß1. CONCLUSIONS: These results suggest that Bindarit in combination with SD208 may be beneficial as medical therapy for the SSCT fibrosis associated with CTS.
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Síndrome del Túnel Carpiano , Quimiocina CCL2 , Síndrome del Túnel Carpiano/tratamiento farmacológico , Quimiocina CCL2/antagonistas & inhibidores , Colágeno Tipo III , Fibroblastos , Fibrosis , Humanos , Factor de Crecimiento Transformador beta , Factor de Crecimiento Transformador beta1RESUMEN
PURPOSE: Replant survival rates have reportedly declined over the past decade. Although this problem is multifactorial, 1 potential solution may include the development of a relevant teaching model. The development of an in vivo animal model that can be used for surgical training could enhance surgeon and resident experience and potentially improve outcomes. Here, we present a novel training model for digit replantation using turkey digits. METHODS: Six mature male Bourbon Red turkeys were included in this study. With the animal under general anesthesia, the third digit on either the left or the right foot was randomly selected and amputated. The medial and lateral digital neurovascular bundles were dissected on both sides and the digit was replanted. Perfusion was confirmed prior to skin closure. The foot was casted prior to extubating the turkeys. Turkeys were then placed in a non-weight-bearing sling. Digit status was evaluated twice daily. RESULTS: All 6 replanted digits were viable immediately after surgery and for at least 24 hours after surgery. The average digit survival was 6 days with a maximum survival of 15 days. All digits were eventually lost owing to a variety of reasons including infection and arterial thrombosis. CONCLUSIONS: The turkey digit proved to be a successful short-term animal training model for digit replantation. Future studies are needed to determine optimum standard surgical procedure and postoperative care to maximize the educational benefits of this training model. CLINICAL RELEVANCE: To establish an animal model that can simulate digital replantation.
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Amputación Traumática , Traumatismos de los Dedos , Amputación Traumática/cirugía , Animales , Dedos , Masculino , Reimplantación , Estudios Retrospectivos , PavosRESUMEN
INTRODUCTION: Synergies of fingers and wrist motion have been incorporated into therapies for finger flexor tendon injuries to improve repair outcomes. Similar synergistic therapy strategies have not been well documented for the thumb. PURPOSE OF THE STUDY: The purpose of this study was to investigate the extent to which wrist motion enables a synergistic effect at the thumb in a cadaveric model by measuring flexor pollicis longus excursion and calculating the moment arm of this tendon at the wrist joint. STUDY DESIGN: This is a basic science research. METHODS: Eight fresh-frozen cadaveric arms were obtained from our anatomical bequest program. The proximal arm was fixed in neutral pronation/supination position, and motion of the wrist was guided through either flexion/extension or radial/ulnar deviation. Fingers were fixed in extension, thumb interphalangeal and metacarpophalangeal joints were fixed in neutral extension, and the carpometacarpal joint was fixed at 30° palmar abduction. The flexor pollicis longus tendon was exposed proximal to the wrist crease and connected to a rotary potentiometer to measure tendon excursion. Optical markers were attached to the hand to capture kinematics. Wrists were moved from a neutral position over the range of flexion and extension and then from the neutral position through the range of radial to ulnar deviation. Moment arms were calculated. RESULTS: Moment arm calculation indicated that the flexor pollicis longus acts as a wrist flexor over the entire motion range and as a weak radial deviator at ulnarly-deviated positions. CONCLUSIONS: This study provides a mechanistic rationale for passive interphalangeal joint motion in varying wrist positions when treating thumb flexor tendon injuries, with benefits seen primarily for wrist extension.
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Rango del Movimiento Articular/fisiología , Tendones/fisiología , Tenodesis , Articulación de la Muñeca/fisiología , Anciano , Anciano de 80 o más Años , Cadáver , Terapia por Ejercicio , Articulaciones de los Dedos/fisiología , Humanos , Persona de Mediana Edad , Pulgar/fisiologíaRESUMEN
OBJECTIVE: The Goutallier classification system is the most commonly used method for grading intramuscular fatty infiltration in rotator cuff tears. This grading system presents low inter-observer reliability and an inability to provide quantitative and repeatable outcomes for intramuscular fat. We determined the correlation and reliability of two methods, the Lava Flex and Ideal IQ MRI techniques, in quantifying volumetric intramuscular fat, while also comparing to the Goutallier method. MATERIALS AND METHODS: The supraspinatus muscles of seventeen cadaveric shoulders were scanned using the Lava Flex and Ideal IQ MRI imaging protocols. Histological analysis was performed on the same muscles. Agreement, reliability, and correlation analyses were performed to compare all outcomes. RESULTS: The Lava Flex protocol took an average of ~ 4 min, while the Ideal IQ required about ~ 11 min to complete. Bland-Altman analysis showed good agreement between the Lava Flex and Ideal IQ [LOA (- 0.10 and 0.05)], and ICC analyses showed excellent reliability (ICC (1,1) 0.948; ICC (2,1) 0.947). There was a 91% correlation between the Lava Flex and Ideal IQ MR protocols. Weighted Kappa analysis between histology and the Goutallier classification showed fair-to-moderate agreement. DISCUSSION: The Lava Flex technique, taking about 30% of the acquisition time, may prevent motion artifacts in outcomes associated with the longer Ideal IQ technique. However, potential magnetic field inhomogeneities should be considered. The Lava Flex technique may be a faster and valid alternative to the Goutallier classification system.
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Tejido Adiposo/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Manguito de los Rotadores/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Cadáver , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Masculino , Persona de Mediana Edad , Reproducibilidad de los ResultadosRESUMEN
INTRODUCTION: Tissue loss as a consequence of congenital anomalies, trauma, malignancy, or gangrene represents a major health care problem in the United States. Because younger individuals are disproportionately affected, the costs are magnified over time and the resultant individual and societal effects are tremendous. The currently available options to restore soft tissue defects are associated with donor site morbidities. Vascularized composite allotransplantation may provide form, function, and esthetics without a donor site; however, it comes with the significant risk associated with toxic immunosuppression (Biomaterials. 2015;61:246-256, Ann Plast Surg. 2015;75(1):112-116, Transplantation. 2009;88(2):203-210). Engineered tissues offer promise in finding viable alternatives to allograft and autologous tissues. In this study, we present our simple and quick method to decellularize a muscle without disrupting the vascular network integrity or the extracellular matrix. Optimizing the decellularization process is a crucial step toward creating an "off-the-shelf" flap that can be used for soft tissue reconstruction. METHODS: The superficial gracilis muscle of 20 rats were harvested on their circulation and decellularized using perfusion with Krebs-Henseleit buffer and sodium dodecyl sulfate for 6 hours. These flaps were evaluated by gross morphology, histology, DNA quantification, integrity of the vascular network, scanning electron microscopy, and transmission electron microscopy. RESULTS: All samples were decellularized successfully as determined by DNA content and histological analysis for cellular content. The vascular network was preserved in all samples. CONCLUSIONS: We present a quick, simple, and affordable method to decellularize a muscle flap through the vascular network. Our proposed method is efficient and can be completed in a significantly shorter time when compared with other methods. It is also safe and does not affect integrity of tissue, and this is essential for a reliable recellularization.
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Músculo Grácil/trasplante , Dodecil Sulfato de Sodio/farmacología , Traumatismos de los Tejidos Blandos/cirugía , Colgajos Quirúrgicos/trasplante , Ingeniería de Tejidos/métodos , Dermis Acelular , Animales , Materiales Biocompatibles , Sistema Libre de Células , Modelos Animales de Enfermedad , Músculo Grácil/citología , Humanos , Perfusión/métodos , Ratas , Sensibilidad y Especificidad , Recolección de Tejidos y ÓrganosRESUMEN
Fibrosis of the subsynovial connective tissue (SSCT) in carpal tunnel syndrome (CTS) patients is increasingly recognized as an important aspect of CTS pathophysiology. In this study, we evaluated the effect of blocking profibrotic pathways in fibroblasts from the SSCT in CTS patients. Fibroblasts were stimulated with transforming growth factor ß1 (TGF-ß1), and then treated either with a specific fibrosis pathway inhibitor targeting TGF-ß receptor type 1 (TßRI), platelet-derived growth factor receptor (PDGFR), epidermal growth factor receptor (EGFR), or vascular endothelial growth factor receptor (VEGFR). Fibrosis array and quantitative real-time polymerase chain reaction of fibrotic genes were evaluated. Array gene expression analysis revealed significant down-regulation of multiple fibrotic genes after treatment with TßRI, PDGFR, and VEGFR inhibitors. No array fibrotic genes were significantly down-regulated with EGFR inhibition. Further gene expression analysis of known CTS fibrosis markers collagen type I A2 (Col1), collagen type III A1 (Col3), connective tissue growth factor (CTGF), and SERPINE1 showed significantly down-regulation after TßRI inhibition. In contrast, VEGFR inhibition significantly down-regulated CTGF and SERPINE1, whereas, PDGFR and EGFR inhibition significantly down-regulated Col3. Taken together the inhibition of TßRI appears to be the primary mediator of fibrotic gene expression in fibroblasts from CTS patients. TGF-ß/Smad activity was further evaluated, and as expected inhibition of Smad activity was significantly down-regulated after inhibition of TßRI, but not with PDGFR, VEGFR, or EGFR inhibition. These results indicate that local therapies specifically targeting TGF-ß signaling alone or in combination offer the potential of a novel local antifibrosis therapy for patients with CTS.
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Síndrome del Túnel Carpiano/tratamiento farmacológico , Receptores ErbB/antagonistas & inhibidores , Fibrosis/patología , Receptores del Factor de Crecimiento Derivado de Plaquetas/antagonistas & inhibidores , Receptores de Factores de Crecimiento Transformadores beta/antagonistas & inhibidores , Receptores de Factores de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Membrana Sinovial/patología , Factor de Crecimiento Transformador beta/metabolismo , Síndrome del Túnel Carpiano/patología , Células Cultivadas , Colágeno Tipo I/biosíntesis , Colágeno Tipo I/genética , Colágeno Tipo III/biosíntesis , Colágeno Tipo III/genética , Tejido Conectivo/patología , Células del Tejido Conectivo/citología , Factor de Crecimiento del Tejido Conjuntivo/biosíntesis , Factor de Crecimiento del Tejido Conjuntivo/genética , Fibroblastos/metabolismo , Fibrosis/tratamiento farmacológico , Humanos , Inhibidor 1 de Activador Plasminogénico/biosíntesis , Inhibidor 1 de Activador Plasminogénico/genética , Membrana Sinovial/citologíaRESUMEN
INTRODUCTION: The aim of this study was to assess alterations in median nerve (MN) biomechanics within the carpal tunnel resulting from ultrasound-guided hydrodissection in a cadaveric model. METHODS: Twelve fresh frozen human cadaver hands were used. MN gliding resistance was measured at baseline and posthydrodissection, by pulling the nerve proximally and then returning it to the origin. Six specimens were treated with hydrodissection, and 6 were used as controls. RESULTS: In the hydrodissection group there was a significant reduction in mean peak gliding resistance of 92.9 ± 34.8 mN between baseline and immediately posthydrodissection (21.4% ± 10.5%; P = 0.001). No significant reduction between baseline and the second cycle occurred in the control group: 9.6 ± 29.8 mN (0.4% ± 5.3%; P = 0.467). DISCUSSION: Hydrodissection can decrease the gliding resistance of the MN within the carpal tunnel, at least in wrists unaffected by carpal tunnel syndrome. A clinical trial of hydrodissection seems justified. Muscle Nerve 57: 25-32, 2018.
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Síndrome del Túnel Carpiano/diagnóstico por imagen , Síndrome del Túnel Carpiano/cirugía , Disección/métodos , Nervio Mediano/diagnóstico por imagen , Nervio Mediano/cirugía , Anciano , Anciano de 80 o más Años , Cadáver , Femenino , Mano/diagnóstico por imagen , Mano/inervación , Mano/cirugía , Humanos , Masculino , Persona de Mediana Edad , Cirugía Asistida por Computador , Ultrasonografía , Muñeca/diagnóstico por imagenRESUMEN
INTRODUCTION: Rotator cuff (RC) tears result in muscle atrophy and fat infiltration within the RC muscles. An estimation of muscle quality and deformation, or extensibility, is useful in selecting the most appropriate surgical procedure. We determined if noninvasive quantitative assessment of intramuscular fat using MRI could be used to predict extensibility of the supraspinatus muscle. METHODS: Seventeen cadaveric shoulders were imaged to assess intramuscular fat infiltration. Extensibility and histological evaluations were then performed. RESULTS: Quantitative fat infiltration positively correlated with histological findings and presented a positive correlation with muscle extensibility (r = 0.69; P = 0.002). Extensibility was not significantly different between shoulders graded with a higher fat content versus those with low fat when implementing qualitative methods. DISCUSSION: A noninvasive prediction of whole-muscle extensibility may directly guide pre-operative planning to determine if the torn edge could efficiently cover the original footprint while aiding in postoperative evaluation of RC repair. Muscle Nerve 57: 129-135, 2018.
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Tejido Adiposo/diagnóstico por imagen , Músculo Esquelético/diagnóstico por imagen , Tejido Adiposo/patología , Adulto , Anciano , Anciano de 80 o más Años , Cadáver , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Músculo Esquelético/patología , Atrofia Muscular/diagnóstico por imagen , Atrofia Muscular/patología , Manguito de los Rotadores/diagnóstico por imagen , Manguito de los Rotadores/patología , Lesiones del Manguito de los Rotadores/diagnóstico por imagen , Lesiones del Manguito de los Rotadores/patología , Tendones/diagnóstico por imagen , Tendones/patologíaRESUMEN
BACKGROUND: Fibroblast behavior and cell-matrix interactions of cells from normal and idiopathic carpal tunnel syndrome (CTS) subsynovial connective tissue (SSCT) with and without Triamcinolone Acetonide (TA) were compared in this study. A cell-seeded gel contraction model was applied to investigate the effect of steroid treatment on SSCT fibroblast gene expression and function. METHODS: SSCT cells were obtained from CTS patients and fresh cadavers. Cells were isolated by mechanical and collagenase digestion. Collagen gels (1 mg/ml) were prepared with SSCT cells (1 × 106/mL). A sterile Petri dish with a cloning ring in the center was prepared. The area between the ring and outer dish was filled with cell-seeded collagen solution and gelled for 1 h. The gel was released from the outer way of the petri dish to allow gel contraction. Cell seeded gels were treated with 10 M triamcinolone acetonide (TA) or vehicle (DMSO) in modified MEM. Every 4 h for 3 days the contracting gels were photographed and areas calculated. Duplicate contraction tests were performed with each specimen, and the averages were used in the analyses, which were conducted using two-factor analysis of variance in a generalized linear model framework utilizing generalized estimating equations (GEE) to account for the correlation between samples. The contraction rate was determined by the area change over time, and the decay time constant was calculated. A customized mechanical test system was used to determine gel stiffness and tensile strength. Gene expression was assessed using Human Fibrosis and Cell Motility PCR arrays. RESULTS: TA-treated gels had a significantly higher contraction rate, tensile strength and stiffness than the untreated gels. Proteinases involved in remodeling had increased expression in TA-treated gels of the patient group. Pro-fibrotic genes and ECM regulators, such as TGF-ß, collagens and integrins, were down-regulated by TA, indicating that TA may work in part by decreasing fibrotic gene expression. CONCLUSIONS: This study showed that TA affects cell-matrix interaction and suppresses fibrotic gene expression in the SSCT cells of CTS patients.
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Síndrome del Túnel Carpiano/tratamiento farmacológico , Fibroblastos/efectos de los fármacos , Glucocorticoides/farmacología , Triamcinolona Acetonida/farmacología , Síndrome del Túnel Carpiano/metabolismo , Colágeno/metabolismo , Femenino , Fibroblastos/metabolismo , Glucocorticoides/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Cultivo Primario de Células , Factor de Crecimiento Transformador beta/metabolismo , Triamcinolona Acetonida/uso terapéuticoRESUMEN
BACKGROUND: Flexor tendon injuries are one of the most common hand injuries and remain clinically challenging for functional restoration. Canine and chicken have been the most commonly used animal models for flexor tendon-related research but possess several disadvantages. The purpose of this study was to explore a potential turkey model for flexor tendon research. METHODS: The third digit from human cadaveric hands, canine forepaws, turkey foot, and chicken foot were used for this study. Six digits in each of four species were studied in detail, comparing anatomy of the flexor apparatus, joint range of motion tendon excursion, tendon cross-sectional area, work of flexion, gliding resistance at the level of the A2 pulley, modulus of elasticity, suture retention strength, and histology across species. RESULTS: Anatomically, the third digit in the four species displayed structural similarities; however, the tendon cross-sectional area of the turkey and human were similar and larger than canine and chicken. Furthermore, the turkey digit resembles the human's finger with the lack of webbing between digits, similar vascularization, tendon excursion, work of flexion, gliding resistance, mechanical properties, and suture holding strength. More importantly, human and turkey tendons were most similar in histological appearance. CONCLUSIONS: Turkey flexor tendons have many properties that are comparable to human flexor tendons which would provide a clinically relevant, economical, nonhuman companion large animal model for flexor tendon research.
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Pollos/anatomía & histología , Perros/anatomía & histología , Modelos Animales , Tendones/anatomía & histología , Pavos/anatomía & histología , Animales , Pollos/fisiología , Pollos/cirugía , Perros/fisiología , Perros/cirugía , Traumatismos de la Mano/cirugía , Humanos , Técnicas In Vitro , Traumatismos de los Tendones/cirugía , Tendones/fisiología , Tendones/cirugía , Pavos/fisiología , Pavos/cirugíaRESUMEN
Pyrene is a polycyclic aromatic hydrocarbon (PAH) commonly observed in aquatic ecosystems, which originates primarily from the incomplete combustion of fossil fuels and the use of petroleum compounds. Pyrene can cause the immune disturbance and oxidative stress, result in immunotoxicity, DNA damage, reduce reproduction significantly, and induce behavioral changes. Marine bivalves are commonly used as bioindicators for marine pollution, and hemolymph is a metabolite transfer medium for PAH pollutant. However, the vital immune indicator responses of pearl oyster Pinctada martensii hemolymph exposed to pyrene is still unclear. Thus, the immunotoxic responses of pyrene on the hemolymph of the Pinctada martensii were investigated in this study. After exposure to pyrene for 7 days, the total number of hemocytes (THC), cell membrane stability (CMS), phagocytic activity (PA) and total glutathione (GSHT) all decreased significantly. Pyrene also caused a significant increase in lipid peroxidation (LPO). Median effective concentrations (EC50) of pyrene on THC (4.5 µg L-1) and LPO (5.2 µg L-1) were lower than those for CMS (13.8 µg L-1), PA (12.1 µg L-1) and GSHT (7.2 µg L-1), which indicates that THC and LPO were more sensitive. Additionally, a clear dose-effect relationship indicated that pyrene stimulated a marked immune response, as well as oxidative stress in P. martensii, which demonstrates the subtle effects of pyrene exposure on marine invertebrates and the potential associated risk.
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Inmunidad Innata/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Pinctada/inmunología , Pirenos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Relación Dosis-Respuesta a Droga , Hemocitos/efectos de los fármacos , Hemocitos/inmunología , Hemolinfa/efectos de los fármacos , Hemolinfa/inmunología , Pinctada/efectos de los fármacosRESUMEN
NCKX1-5 are proteins involved in K+-dependent Na+/Ca2+ exchange in various signal tissues. Here we present a homology model of NCKX2 based on the crystal structure of the NCX_Mj transporter found in Methanoccocus jannaschii. Molecular dynamics simulations were performed on the resultant wild-type NCKX2 model and two mutants (D548N and D575N) loaded with either four Na+ ions or one Ca2+ ion and one K+ ion, in line with the experimentally observed transport stoichiometry. The selectivity of the active site in wild-type NCKX2 for Na+, K+, and Li+ and the electrostatic interactions of the positive Na+ ions in the negatively charged active site of wild-type NCKX2 and the two mutants were evaluated from free energy perturbation calculations. For validation of the homology model, our computational results were compared to available experimental data obtained from numerous prior functional studies. The NCKX2 homology model is in good agreement with the discussed experimental data and provides valuable insights into the structure of the active site, which is lined with acidic and polar residues. The binding of the potassium and calcium ions is accomplished via Asp 575 and 548, respectively. Mutation of these residues to Asn alters the functionality of NCKX2 because of the elimination of the favorable carboxylate-cation interactions. The knowledge obtained from the NCKX2 model can be transferred to other isoforms of the NCKX family: newly discovered pathological mutations in NCKX4 and NCKX5 affect residues that are involved in ion binding and/or transport according to our homology model.
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Proteínas Arqueales/metabolismo , Cationes/metabolismo , Methanococcales/metabolismo , Intercambiador de Sodio-Calcio/metabolismo , Secuencia de Aminoácidos , Proteínas Arqueales/química , Proteínas Arqueales/genética , Sitios de Unión/genética , Calcio/química , Calcio/metabolismo , Dominio Catalítico , Cristalografía por Rayos X , Methanococcales/genética , Simulación de Dinámica Molecular , Mutación , Potasio/química , Potasio/metabolismo , Unión Proteica , Dominios Proteicos , Homología de Secuencia de Aminoácido , Intercambiador de Sodio-Calcio/química , Intercambiador de Sodio-Calcio/genética , Electricidad Estática , TermodinámicaRESUMEN
Neurotransmitter:sodium symporters (NSSs) terminate neurotransmission by Na(+)-dependent reuptake of released neurotransmitters. Previous studies suggested that Na(+)-binding reconfigures dynamically coupled structural elements in an allosteric interaction network (AIN) responsible for function-related conformational changes, but the intramolecular pathway of this mechanism has remained uncharted. We describe a new approach for the modeling and analysis of intramolecular dynamics in the bacterial NSS homolog LeuT. From microsecond-scale molecular dynamics simulations and cognate experimental verifications in both LeuT and human dopamine transporter (hDAT), we apply the novel method to identify the composition and the dynamic properties of their conserved AIN. In LeuT, two different perturbations disrupting Na(+) binding and transport (i.e. replacing Na(+) with Li(+) or the Y268A mutation at the intracellular gate) affect the AIN in strikingly similar ways. In contrast, other mutations that affect the intracellular gate (i.e. R5A and D369A) do not significantly impair Na(+) cooperativity and transport. Our analysis shows these perturbations to have much lesser effects on the AIN, underscoring the sensitivity of this novel method to the mechanistic nature of the perturbation. Notably, this set of observations holds as well for hDAT, where the aligned Y335A, R60A, and D436A mutations also produce different impacts on Na(+) dependence. Thus, the detailed AIN generated from our method is shown to connect Na(+) binding with global conformational changes that are critical for the transport mechanism. That the AIN between the Na(+) binding sites and the intracellular gate in bacterial LeuT resembles that in eukaryotic hDAT highlights the conservation of allosteric pathways underlying NSS function.
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Neurotransmisores/química , Proteínas de Transporte de Neurotransmisores en la Membrana Plasmática/química , Sodio/química , Sitio Alostérico , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/química , Escherichia coli/metabolismo , Humanos , Iones , Ligandos , Litio/química , Metales/química , Simulación de Dinámica Molecular , Mutación , Unión Proteica , Conformación ProteicaRESUMEN
Quantitative computed tomography-based finite-element analysis (QCT/FEA) has become increasingly popular in an attempt to understand and possibly reduce vertebral fracture risk. It is known that scanning acquisition settings affect Hounsfield units (HU) of the CT voxels. Material properties assignments in QCT/FEA, relating HU to Young's modulus, are performed by applying empirical equations. The purpose of this study was to evaluate the effect of QCT scanning protocols on predicted stiffness values from finite-element models. One fresh frozen cadaveric torso and a QCT calibration phantom were scanned six times varying voltage and current and reconstructed to obtain a total of 12 sets of images. Five vertebrae from the torso were experimentally tested to obtain stiffness values. QCT/FEA models of the five vertebrae were developed for the 12 image data resulting in a total of 60 models. Predicted stiffness was compared to the experimental values. The highest percent difference in stiffness was approximately 480% (80 kVp, 110 mAs, U70), while the lowest outcome was â¼1% (80 kVp, 110 mAs, U30). There was a clear distinction between reconstruction kernels in predicted outcomes, whereas voltage did not present a clear influence on results. The potential of QCT/FEA as an improvement to conventional fracture risk prediction tools is well established. However, it is important to establish research protocols that can lead to results that can be translated to the clinical setting.
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Absorciometría de Fotón/métodos , Densidad Ósea/fisiología , Modelos Biológicos , Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Columna Vertebral/diagnóstico por imagen , Columna Vertebral/fisiología , Tomografía Computarizada por Rayos X/métodos , Anciano de 80 o más Años , Cadáver , Simulación por Computador , Módulo de Elasticidad/fisiología , Femenino , Análisis de Elementos Finitos , Humanos , Imagenología Tridimensional/métodos , Fantasmas de Imagen , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Estrés MecánicoRESUMEN
PURPOSE: To investigate the alteration of passive stiffness in the supraspinatus muscle after double-row (DR) and knotless transosseous-equivalent (KL-TOE) repair techniques, using shear wave elastography (SWE) in cadavers with rotator cuff tears. We also aimed to compare altered muscular stiffness after these repairs to that obtained from shoulders with intact rotator cuff tendon. METHODS: Twelve fresh-frozen cadaveric shoulders with rotator cuff tear (tear size: small [6], medium-large [6]) were used. Passive stiffness of 4 anatomic regions in the supraspinatus muscle was measured based on an established SWE method. Each specimen underwent DR and KL-TOE footprint repairs at 30° glenohumeral abduction. SWE values, obtained at 0°, 10°, 20°, 30°, 60°, and 90° abduction, were assessed in 3 different conditions: preoperative (torn) and postoperative conditions with the 2 techniques. The increased ratio of SWE values after repair was compared among the 4 regions to assess stiffness distribution. In addition, SWE values were obtained on 12 shoulders with intact rotator cuff tendons as control. RESULTS: In shoulders with medium-large-sized tears, supraspinatus muscles showed an increased passive stiffness after rotator cuff repairs, and this was significantly observed at adducted positions. KL-TOE repair showed uniform stiffness changes among the 4 regions of the supraspinatus muscle (mean, 189% to 218% increase after repair), whereas DR repair caused a significantly heterogeneous stiffness distribution within the muscle (mean, 187% to 319% after repair, P = .002). Although a repair-induced increase in muscle stiffness was observed also in small-sized tears, there were no significant differences in repaired stiffness changes between DR and KL-TOE (mean, 127% to 138% and 127% to 130% after repairs, respectively). Shoulders with intact rotator cuff tendon showed uniform SWE values among the 4 regions of the supraspinatus muscle (mean, 38.2 to 43.0 kPa). CONCLUSIONS: Passive stiffness of the supraspinatus muscle increases after rotator cuff repairs for medium-large-sized tears. KL-TOE technique for the medium-large-sized tear provided a more uniform stiffness distribution across the repaired supraspinatus muscles compared with the DR technique. CLINICAL RELEVANCE: Based on this insight, investigating rotator cuff muscle stiffness changes, further studies using SWE may determine the optimal repair technique for various sizes of rotator cuff tears.
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Artroscopía/métodos , Músculo Esquelético/fisiopatología , Lesiones del Manguito de los Rotadores/cirugía , Técnicas de Sutura , Fenómenos Biomecánicos , Cadáver , Diagnóstico por Imagen de Elasticidad , Humanos , Músculo Esquelético/diagnóstico por imagenRESUMEN
HYPOTHESIS: A composite of multilayer tendon slices (COMTS) seeded with bone marrow stromal cells (BMSCs) may impart mechanical and biologic augmentation effects on supraspinatus tendon repair under tension, thereby improving the healing process after surgery in rats. METHODS: Adult female Lewis rats (n = 39) underwent transection of the supraspinatus tendon and a 2-mm tendon resection at the distal end, followed by immediate repair to its bony insertion site under tension. Animals received 1 of 3 treatments at the repair site: (1) no augmentation, (2) COMTS augmentation alone, or (3) BMSC-seeded COMTS augmentation. BMSCs were labeled with a fluorescent cell marker. Animals were euthanized 6 weeks after surgery, and the extent of healing of the repaired supraspinatus tendon was evaluated with biomechanical testing and histologic analysis. RESULTS: Histologic analysis showed gap formation between the repaired tendon and bone in all specimens, regardless of treatment. Robust fibrous tissue was observed in rats with BMSC-seeded COMTS augmentation; however, fibrous tissue was scarce within the gap in rats with no augmentation or COMTS-only augmentation. Labeled transplanted BMSCs were observed throughout the repair site. Biomechanical analysis showed that the repairs augmented with BMSC-seeded COMTS had significantly greater ultimate load to failure and stiffness compared with other treatments. However, baseline (time 0) data showed that COMTS-only augmentation did not increase mechanical strength of the repair site. CONCLUSION: Although the COMTS scaffold did not increase the initial repair strength, the BMSC-seeded scaffold increased healing strength and stiffness 6 weeks after rotator cuff repair in a rat model.