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INTRODUCTION: Skeletal muscle function is an important prognostically relevant indicator in patients with acute leukemia (AL), but skeletal dysfunction during chemotherapy is not well understood. This study aimed to investigate the factors that influence changes in skeletal muscle function from before the start of chemotherapy to before allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: This was a retrospective cohort study that included 90 patients with AL who underwent chemotherapy before transplantation to perform allo-HSCT (men, 67.3%; median age, 53 years). The outcome measure was defined as changes in skeletal muscle function from before chemotherapy to before allo-HSCT, and was assessed by measuring the psoas muscle index (PMI) as skeletal muscle quantity and computed tomography values (CTV) as skeletal muscle quality using a computed tomography scanner. We examined the differences in PMI and CTV before chemotherapy and allo-HSCT, and the factors associated with changes in PMI. RESULT: The mean PMI for before chemotherapy and allo-HSCT were 4.6 ± 1.4 cm2/m2 and 4.0 ± 1.3 cm2/m2 and significant differences were observed (p < 0.001). However, the mean CTV before chemotherapy and allo-HSCT were 47.3 ± 4.5 HU and 47.4 ± 5.0 HU, respectively, and no significant differences were found (p = 0.798). In stepwise multiple regression analysis, age and sex were identified as factors related to changes in PMI (age, p = 0.019; sex, p = 0.001). CONCLUSION: We found that skeletal muscle quantity decreased during chemotherapy in patients with AL and was influenced by male sex and older age. TRIAL REGISTRATION NUMBER: TRIAL REGISTRATION NUMBER: 34-096(11,243). Date of registration: September 11, 2023.
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Trasplante de Células Madre Hematopoyéticas , Músculo Esquelético , Humanos , Masculino , Persona de Mediana Edad , Femenino , Estudios Retrospectivos , Adulto , Trasplante de Células Madre Hematopoyéticas/métodos , Músculo Esquelético/fisiopatología , Anciano , Tomografía Computarizada por Rayos X/métodos , Estudios de Cohortes , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/terapia , Músculos Psoas , Adulto Joven , Leucemia/terapia , Leucemia/tratamiento farmacológico , Trasplante Homólogo/métodos , Enfermedad Aguda , Antineoplásicos/efectos adversos , Antineoplásicos/administración & dosificaciónRESUMEN
Securing high-quality cell sources is important in regenerative medicine. In this study, we developed a device that can accumulate autologous stem cells in the body. When small wire-assembled molds were embedded in the dorsal subcutaneous pouches of beagles for several weeks, collagen-based tissues with minimal inflammation formed inside the molds. At 3 weeks of embedding, the outer areas of the tissues were composed of immature type III collagen with large amounts of cells expressing SSEA3 or SSEA4 markers, in addition to growth factors such as HGF or VEGF. When separated from the tissues by collagenase treatment, approximately four million cells with a proportion of 70% CD90-positive and 20% SSEA3- or SSEA4-positive cells were recovered from the single mold. The cells could differentiate into bone or cartilage cells. The obtained cell-containing tissues are expected to have potential as therapeutic materials or cell sources in regenerative medicine.
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Autologous-engineered artificial tissues constitute an ideal alternative for radical surgery in terms of natural anticoagulation, self-repair, tissue regeneration, and the possibility of growth. Previously, we focused on the development and practical application of artificial tissues using "in-body tissue architecture (iBTA)", a technique that uses living bodies as bioreactors. This study aimed to further develop iBTA by fabricating tissues with diverse shapes and evaluating their physical properties. Although the breaking strength increased with tissue thickness, the nominal breaking stress increased with thinner tissues. By carving narrow grooves on the outer periphery of an inner core with narrow grooves, we fabricated approximately 2.2 m long cord-shaped tissues and net-shaped tissues with various designs. By assembling the two inner cores inside the branched stainless-steel pipes, a large graft with branching was successfully fabricated, and its aortic arch replacement was conducted in a donor goat without causing damage. In conclusion, by applying iBTA technology, we have made it possible, for the first time, to create tissues of various shapes and designs that are difficult using existing tissue-engineering techniques. Thicker iBTA-induced tissues exhibited higher rupture strength; however, rupture stress was inversely proportional to thickness. These findings broaden the range of iBTA-induced tissue applications.
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Urinary tract diseases are common in cats, and often require surgical reconstruction. Here, to explore the possibility of urinary tract reconstruction in cats using in-body tissue architecture (iBTA), biosheets fabricated using iBTA technology were implanted into the feline bladder and the regeneration process was histologically evaluated. The biosheets were prepared by embedding molds into the dorsal subcutaneous pouches of six cats for 2 months. A section of the bladder wall was removed, and the biosheets were sutured to the excision site. After 1 and 3 months of implantation, the biosheets were harvested and evaluated histologically. Implantable biosheets were formed with a success rate of 67%. There were no major complications following implantation, including tissue rejection, severe inflammation, or infection. Urinary incontinence was also not observed. Histological evaluation revealed the bladder lumen was almost entirely covered by urothelium after 1 month, with myofibroblast infiltration into the biosheets. After 3 months, the urothelium became multilayered, and mature myocytes and nerve fibers were observed at the implantation site. In conclusion, this study showed that tissue reconstruction using iBTA can be applied to cats, and that biosheets have the potential to be useful in both the structural and functional regeneration of the feline urinary tract.
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The reaching motion to the back of the head with the hand is an important movement for daily living. The scores of upper limb function tests used in clinical practice alone are difficult to use as a reference when planning exercises for movement improvements. This cross-sectional study aimed to clarify in patients with mild hemiplegia the kinematic characteristics of paralyzed and non-paralyzed upper limbs reaching the occiput. Ten patients with post-stroke hemiplegia who attended the Department of Rehabilitation Medicine of the Jikei University Hospital and met the eligibility criteria were included. Reaching motion to the back of the head by the participants' paralyzed and non-paralyzed upper limbs was measured using three-dimensional motion analysis, and the motor time, joint angles, and angular velocities were calculated. Repeated measures multivariate analysis of covariance was performed on these data. After confirming the fit to the binomial logistic regression model, the cutoff values were calculated using receiver operating characteristic curves. Pattern identification using random forest clustering was performed to analyze the pattern of motor time and joint angles. The cutoff values for the movement until the hand reached the back of the head were 1.6 s for the motor time, 55° for the maximum shoulder joint flexion angle, and 145° for the maximum elbow joint flexion angle. The cutoff values for the movement from the back of the head to the hand being returned to its original position were 1.6 s for the motor time, 145° for the maximum elbow joint flexion angle, 53°/s for the maximum angular velocity of shoulder joint abduction, and 62°/s for the maximum angular velocity of elbow joint flexion. The numbers of clusters were three, four, and four for the outward non-paralyzed side, outward and return paralyzed side, and return non-paralyzed side, respectively. The findings obtained by this study can be used for practice planning in patients with mild hemiplegia who aim to improve the reaching motion to the occiput.
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Hemiplejía , Rango del Movimiento Articular , Extremidad Superior , Humanos , Hemiplejía/fisiopatología , Masculino , Estudios Transversales , Femenino , Persona de Mediana Edad , Anciano , Extremidad Superior/fisiopatología , Fenómenos Biomecánicos , Rango del Movimiento Articular/fisiología , Articulación del Hombro/fisiopatología , Articulación del Codo/fisiopatología , Accidente Cerebrovascular/fisiopatología , Accidente Cerebrovascular/complicaciones , Movimiento/fisiologíaRESUMEN
The administration of mesenchymal stem cells (MSCs) has a positive effect on wound healing; however, the lack of adequate MSC engraftment at the wound site is a major limiting factor in current MSC-based therapies. In this study, a biosheet prepared using in-body tissue architecture (iBTA) was used as a material to address these problems. This study aimed to assess and evaluate whether biosheets containing somatic stem cells would affect the wound healing process in dogs. Biosheets were prepared by subcutaneously embedding molds in beagles. These were then evaluated grossly and histologically, and the mRNA expression of inflammatory cytokines, interleukins, and Nanog was examined in some biosheets. Skin defects were created on the skin of the beagles to which the biosheets were applied. The wound healing processes of the biosheet and control (no biosheet application) groups were compared for 8 weeks. Nanog mRNA was expressed in the biosheets, and SSEA4/CD105 positive cells were observed histologically. Although the wound contraction rates differed significantly in the first week, the biosheet group tended to heal faster than the control group. This study revealed that biosheets containing somatic stem cells may have a positive effect on wound healing.
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INTRODUCTION: Chronic wounds caused by diabetes or lower-extremity artery disease are intractable because the wound healing mechanism becomes ineffective due to the poor environment of the wound bed. Biosheets obtained using in-body tissue architecture (iBTA) are collagen-based membranous tissue created within the body and which autologously contain various growth factors and somatic stem cells including SSEA4-posituve cells. When applied to a wound, granulation formation can be promoted and epithelialization may even be achieved. Herein, we report our clinical treatment experience with seven cases of intractable diabetic foot ulcers. CASES: Seven patients, from 46 to 93 years old, had large foot ulcers including in the heel area, which were failing to heal with standard wound treatment. METHODS: Two or four Biosheet-forming molds were embedded subcutaneously in the chest or abdomen, and after 3 to 6 weeks, the molds were removed. Biosheets that formed inside the mold were obtained and applied directly to the wound surface. RESULTS: In all cases, there were no problems with the mold's embedding and removal procedures, and Biosheets were formed without any infection or inflammation during the embedding period. The Biosheets were simply applied to the wounds, and in all cases they adhered within one week, did not fall off, and became integrated with the wound surface. Complete wound closure was achieved within 8 weeks in two cases and within 5 months in two cases. One patient was lost due to infective endocarditis from septic colitis. One case required lower leg amputation due to wound recurrence, and one case achieved wound reduction and wound healing in approximately 9 months. CONCLUSIONS: Biosheets obtained via iBTA promoted wound healing and were extremely useful for intractable diabetic foot ulcers involving the heel area.
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This study investigated six-month outcomes of first models of ascending aortic replacement. The molds used to produce the Biotube were implanted subcutaneously in goats. After 2-3 months, the molds were explanted to obtain the Biotubes (inner diameter, 12 mm; wall thickness, 1.5 mm). Next, we performed ascending aortic replacement using the Biotube in five allogenic goats. At 6 months, the animals underwent computed tomography (CT) and histologic evaluation. As a comparison, we performed similar surgeries using glutaraldehyde-fixed autologous pericardial rolls or pig-derived heterogenous Biotubes. At 6 months, CT revealed no aneurysmalization of the Biotube or pseudoaneurysm formation. The histologic evaluation showed development of endothelial cells, smooth muscle cells, and elastic fibers along the Biotube. In the autologous pericardium group, there was no evidence of new cell development, but there was calcification. The histologic changes observed in the heterologous Biotube group were similar to those in the allogenic Biotube group. However, there was inflammatory cell infiltration in some heterologous Biotubes. Based on the above, we could successfully create the world's first Biotube-based ascending aortic replacement models. The present results indicate that the Biotube may serve as a scaffold for aortic tissue regeneration.
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Background/Objectives: Upper-limb function of chronic stroke patients declined when outpatient rehabilitation was interrupted and outings restricted, owing to the novel coronavirus infection (COVID-19) pandemic. We investigated whether these patients recovered upper-limb function post-resumption of outpatient rehabilitation. Methods: In this observational study, 43 chronic stroke hemiparesis patients with impaired upper extremity function were scored for limb function via the Fugl-Meyer assessment of the upper extremity (FMA-UE) and the Action Research Arm Test (ARAT) after a structured interview, evaluation, and intervention. Scores at 6 and 3 months pre- and 3 months post-rehabilitation interruption were examined retrospectively; scores immediately and at 3 and 6 months post-resumption of care were examined prospectively. The amount of change for each time period and an analysis of covariance were performed with time as a factor, changes in the FMA-UE and the ARAT scores as dependent variables, and statistical significance at 5%. Results: The time of evaluation significantly impacted the total score, as well as part C and part D of FMA-UE and total, pinch, and gross movement of the ARAT. Post-hoc tests showed that the magnitude of change in limb-function scores from immediately to 3 months post-resumption was significantly higher than the change from 3 months pre- to immediately post-interruption for the total score and part D of the FMA-UE, as well as grip and gross movement of the ARAT (p < 0.05). Conclusions: Upper-limb functional decline in chronic stroke patients, caused by the COVID-19 pandemic-related therapy interruption and outing restrictions, was resolved approximately 3 months post-resumption of rehabilitation therapy. Our data can serve as reference standards for planning and evaluating treatment for chronic stroke patients with inactivity-related impaired upper-limb function.
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Biotubes are autologous tubular tissues developed within a patient's body through in-body tissue architecture, and they demonstrate high potential for early clinical application as a vascular replacement. In this pilot study, we used large animals to perform implantation experiments in preparation for preclinical testing of Biotube. The biological response after Biotube implantation was histologically evaluated. The designed Biotubes (length: 50 cm, internal diameter: 4 mm, and wall thickness: 0.85 mm) were obtained by embedding molds on the backs of six goats for a predetermined period (1-5 months). The same goats underwent bypass surgery on the carotid arteries using Biotubes (average length: 12 cm). After implantation, echocardiography was used to periodically monitor patency and blood flow velocity. The maximum observation period was 6 months, and tissue analysis was conducted after graft removal, including the anastomosis. All molds generated Biotubes that exceeded the tensile strength of normal goat carotid arteries, and eight randomly selected Biotubes were implanted. Thrombotic occlusion occurred immediately postoperatively (1 tube) if anticoagulation was insufficient, and two tubes, with insufficient Biotube strength (<5 N), were ruptured within a week. Five tubes maintained patency for >2 months without aneurysm formation. The spots far from the anastomosis became stenosed within 3 months (3 tubes) when Biotubes had a wide intensity distribution, but the shape of the remaining two tubes remained unchanged for 6 months. The entire length of the bypass region was walled with an αSMA-positive cell layer, and an endothelial cell layer covered most of the lumen at 2 months. Complete endothelial laying of the luminal surface was obtained at 3 months after implantation, and a vascular wall structure similar to that of native blood vessels was formed, which was maintained even at 6 months. The stenosis was indicated to be caused by fibrin adhesion on the luminal surface, migration of repair macrophages, and granulation formation due to the overproliferation of αSMA-positive fibroblasts. We revealed the importance of Biotubes that are homogeneous, demonstrate a tensile strength > 5 N, and are implanted under appropriate antithrombotic conditions to achieve long-term patency of Biotube. Further, we clarified the Biotube regeneration process and the mechanism of stenosis. Finally, we obtained the necessary conditions for a confirmatory implant study planned shortly.
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The treatment of long-tracheal lesion is difficult because there are currently no viable grafts for tracheal replacement. To solve this problem, we have developed an autologous Tissue-Engineered Trachea (aTET), which is made up of collagenous tissues and cartilage-like structures derived from rat chondrocytes. This graft induced successful long-term survival in a small-animal experiment in our previous study. In this study, we investigated the regeneration process of an aTET to attain reproducible success. We prepared an aTET by using a specially designed mold and performed patch tracheoplasty with an aTET. We assigned twenty-seven rats to three groups according to the three types of patch grafts used: aTET patches (the aTET group), fresh tracheal autograft patches (the Ag group), or polylactic acid and polycaprolactone copolymer sheets (the PPc group). In each group, gross and histological evaluations were performed at 1 month (n = 3), 3 months (n = 3), and 6 months (n = 3) after implantation. We obtained high survival rates in all groups, but only the PPc group attained thick tracheal walls with granular tissues and no tracheal regeneration. On the other hand, the aTET and Ag groups reproducibly achieved complete tracheal regeneration in 6 months. So, an aTET could be a promising candidate for tracheal regeneration grafts.
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Introduction: Ureteral injuries require surgical intervention as they lead to loss of renal function. The current reconstructive techniques for long ureteral defects are problematic. Consequently, this study aimed to reconstruct the ureter in a rat model using subcutaneously prepared autologous collagen tubes (Biotubes). Methods: The lower ureter of LEW/SsNSlc rats was ligated to dilate the ureter to make anastomosis easier, and reconstruction was performed six days later by anastomosing the dilated ureter and bladder with a Biotube that was prepared subcutaneously in syngeneic rats. Some rats underwent left nephrectomy and ureter reconstruction simultaneously as negative controls to evaluate the effects of urine flow on patency. The other rats were divided into three groups as follows: a group in which the ureter was reconstructed with the Biotube alone, a group in which cardiomyocyte sheets made from the neonatal hearts of syngeneic rats were wrapped around the Biotube, and a group in which an adipose-derived stem cell sheets made from the inguinal fat of adult syngeneic rats were wrapped. Contrast-enhanced computed tomography and pathological evaluations were performed two weeks after reconstruction. Result: In the Biotube alone group, all tubes were occluded and hydronephrosis developed, whereas the urothelium regenerated beyond the anastomosis when the left kidney was not removed, suggesting that urothelial epithelial spread occurred with urinary flow. The patency of the ureteral lumen was obtained in some rats in the cardiomyocyte sheet covered group, whereas stricture or obstruction of the reconstructed ureter was observed in all rats in the other groups. Pathological evaluation revealed a layered urothelial structure in the cardiomyocyte sheet covered group, although only a small amount of cardiomyocyte sheets remained. Conclusion: Urinary flow may support the epithelial spread of the urothelium into the reconstructed ureter. Neonatal rat cardiomyocyte sheets supported the patency of the regenerated ureter with a layered urothelium.
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We perform physical therapy combined with repetitive transcranial magnetic stimulation (rTMS) in stroke patients with hemiplegia in the maintenance phase with the intent of improving the support of paralyzed leg. In gait evaluation in patients with hemiplegia, it is important to assess elements related to coordination carefully. rTMS therapy is effective in alleviating the tension of upper limbs. As rTMS helps upper-limb swing to become evident during gait, it makes trunk rotation necessary for left-right coordination appear more easily. As a result, rTMS has potential for improved upper-limb swing or trunk rotation. Post-rTMS therapy may prepare for the environment suitable for hip extending the stance phase of the paralyzed side. In physical therapy, it is advisable to practice standing up, maintaining standing posture or walking by making good use of these effects. We conduct practices in combination with the following: standing up focusing on load evenly distributed on both sides, standing on slant-board training, which enables forward shift of center of mass, walking by fixating upper limbs to the back of the body with the intent of extending the stance phase of the paralyzed side, and increasing trunk rotation. It is also necessary to discuss the combination with injection with botulinum toxin, which suppresses spasticity of ankle plantar flexors with the physician. Gait is associated with a variety of factors and has significant intrapatient and interpatient variations. In this regard, physiotherapists are required to develop a treatment program based on a quantitative evaluation, especially, in patients with hemiplegia.
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Histologic evaluations revealed excessive accumulations of macrophages and absence of fibroblastic interstitial cells in explanted bioprosthetic valves. Comprehensive gene and protein expression analysis and histology unveiled an accumulation of fibrinogen and plasminogen, an activator of infiltrated macrophages, from degenerated valve surfaces in the interstitial spaces. These pathologies were completely reproduced in a goat model replaced with an autologous pericardium-derived aortic valve. Further preclinical animal experiments using goats demonstrated that preventing infiltration of macrophages and circulating proteins by increasing collagen density and leaflet strength is an effective treatment option.
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Although knee extensor muscle strength is strongly associated with postoperative walking ability (PWA) in patients undergoing total knee arthroplasty (TKA), few studies have considered the impact of both knee extensor and flexor muscle strength. This study aimed to determine whether operative side knee flexor and extensor muscle strength before surgery affects the PWA of patients who undergo TKA while accounting for potential covariates. This multicenter retrospective cohort study involved four university hospitals, and patients who underwent unilateral primary TKA were included. The outcome measure was the 5-m maximum walking speed test (MWS), which was completed 12 weeks postoperatively. Muscle strength was measured as the maximum isometric muscle strength required for knee flexor and extensor. Three multiple regression models with a progressively larger number of variables were developed to determine the predictors of 5-m MWS at 12 weeks post-TKA surgery. One hundred thirty-one patients who underwent TKA were enrolled in the study (men, 23.7%; mean age, 73.4 ± 6.9 years). Age, sex, operative side knee flexor muscle strength before surgery, Japanese Orthopaedic Association knee score, and preoperative walking ability were significantly associated with PWA in the final model of the multiple regression analysis ( R2 = 0.35). The current findings suggest that the operative side knee flexor muscle strength before surgery is a robust modifiable predictor of improved PWA. We believe that further validation is needed to determine the causal relationship between preoperative muscle strength and PWA.
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Artroplastia de Reemplazo de Rodilla , Osteoartritis de la Rodilla , Masculino , Humanos , Anciano , Anciano de 80 o más Años , Estudios Retrospectivos , Articulación de la Rodilla/cirugía , Fuerza Muscular/fisiología , Osteoartritis de la Rodilla/cirugía , Caminata/fisiologíaRESUMEN
INTRODUCTION: Poor skeletal muscle function is relatively high in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), leading to various negative health outcomes. This study aimed to investigate the relationship between the quantity and quality of skeletal muscle before transplantation and the short-to long-term survival after transplantation in patients undergoing allo-HSCT. METHODS: This retrospective cohort study included 156 patients undergoing allo-HSCT (men, 67.3 %; median age, 53 years; interquartile range, 42-61 years). The quantity and quality of the skeletal muscle were measured at the psoas major at the level of the third lumbar vertebrae using a computed tomography (CT) and were defined as psoas muscle index (PMI) and CT values (CTV), respectively. The outcome measure of this study was overall survival (OS) after allo-HSCT, and we examined the relationship between survival at three time points (6, 12, and 24 months) after transplantation, PMI, and CTV. RESULTS: PMI was significantly associated with survival at all time points in the crude model (P < 0.001), and a significant association was observed in the fully adjusted model (P < 0.01). CTV was significantly associated with survival at all time points in the crude model (P < 0.05), but not in the fully adjusted model (P > 0.05). CONCLUSIONS: We found that the quantity and quality of the skeletal muscle before transplantation were significantly associated with OS at 6, 12, and 24 months after transplantation, showing a particularly robust association with quantity.
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Trasplante de Células Madre Hematopoyéticas , Músculo Esquelético , Masculino , Humanos , Persona de Mediana Edad , Estudios Retrospectivos , Músculo Esquelético/diagnóstico por imagen , Trasplante de Células Madre Hematopoyéticas/métodos , Trasplante HomólogoRESUMEN
Repetitive transcranial magnetic stimulation (rTMS) with intensive occupational therapy improves upper limb motor paralysis and activities of daily living after stroke; however, the degree of improvement according to paralysis severity remains unverified. Target activities of daily living using upper limb functions can be established by predicting the amount of change after treatment for each paralysis severity level to further aid practice planning. We estimated post-treatment score changes for each severity level of motor paralysis (no, poor, limited, notable, and full), stratified according to Action Research Arm Test (ARAT) scores before combined rTMS and intensive occupational therapy. Motor paralysis severity was the fixed factor for the analysis of covariance; the delta (post-pre) of the scores was the dependent variable. Ordinal logistic regression analysis was used to compare changes in ARAT subscores according to paralysis severity before treatment. We implemented a longitudinal, prospective, interventional, uncontrolled, and multicenter cohort design and analyzed a dataset of 907 patients with stroke hemiplegia. The largest treatment-related changes were observed in the Limited recovery group for upper limb motor paralysis and the Full recovery group for quality-of-life activities using the paralyzed upper limb. These results will help predict treatment effects and determine exercises and goal movements for occupational therapy after rTMS.
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During recovery from upper limb motor paralysis after stroke, it is important to (1) set the exercise difficulty level according to the motor paralysis severity, (2) provide adequate exercises, and (3) motivate the patient to achieve the goal. However, these factors have not been well-formulated. This multicenter, randomized controlled trial study aims to examine the therapeutic effects of these three factors on patients undergoing a novel intervention using repetitive transcranial magnetic stimulation and intensive one-to-one training (NEURO®) and to formulate a corresponding research protocol. The control group will receive conventional NEURO® occupational therapy. In the intervention group, four practice plans will be selected according to the Fugl-Meyer assessment (FMA-UE) scores of the upper extremity. The goal is to predict the post-treatment outcomes based on the pre-treatment FMA-UE scores. Based on the degree of difficulty and amount of practice required, we can formulate a practice plan to promote upper limb motor recovery. This occupational therapy plan will be less influenced by the therapist's skill, facilitating effective rehabilitation. The study findings may be utilized to promote upper limb motor paralysis recovery and provide a basis for proposing activities of daily living adapted to upper limb function.
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Tracheas have a tubular structure consisting of cartilage rings continuously joined by a connective tissue membrane comprising a capillary network for tissue survival. Several tissue engineering efforts have been devoted to the design of scaffolds to produce complex structures. In this study, we successfully fabricated an artificial materials-free autologous tracheal analogue with engraftment ability by combining in vitro cell self-aggregation technique and in-body tissue architecture. The cartilage rings prepared by aggregating chondrocytes on designated culture grooves that induce cell self-aggregation were alternately connected to the connective tissues to form tubular tracheal analogues by subcutaneous embedding as in-body tissue architecture. The tracheal analogues allogeneically implanted into the rat trachea matured into native-like tracheal tissue by covering of luminal surfaces by the ciliated epithelium with mucus-producing goblet cells within eight months after implantation, while maintaining their structural integrity. Such autologous tracheal analogues would provide a foundation for further clinical research on the application of tissue-engineered tracheas to ensure their long-term functionality.
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Ingeniería de Tejidos , Tráquea , Ratas , Animales , Ingeniería de Tejidos/métodos , Trasplante Autólogo , Condrocitos , RegeneraciónRESUMEN
There are no small-diameter, long artificial vascular grafts for below-knee bypass surgery in chronic limb-threatening ischemia. We have developed tissue-engineered vascular grafts called "Biotubes®" using a completely autologous approach called in-body tissue architecture (iBTA). This study aimed at pre-implantation evaluation of Biotube and its in vivo preparation device, Biotube Maker, for use in below-knee bypass surgery. Forty nine makers were subcutaneously embedded into 17 goats for predetermined periods (1, 2, or 3 months). All makers produced Biotubes as designed without inflammation over all periods, with the exception of a few cases with minor defects (success rate: 94%). Small hole formation occurred in only a few cases. All Biotubes obtained had an inner diameter of 4 mm and a length of 51 to 52 cm with a wall thickness of 594 ± 97 µm. All Biotubes did not kink when completely bent under an internal pressure of 100 mmHg and did not leak without any deformation under a water pressure of 200 mmHg. Their burst strength was 2409 ± 473 mmHg, and suture retention strength was 1.75 ± 0.27 N, regardless of the embedding period, whereas tensile strength increased from 7.5 ± 1.3 N at 1 month to 9.7 ± 2.0 N at 3 months with the embedding period. The amount of water leakage from the needle holes prepared in the Biotube wall was approximately 1/7th of that in expanded polytetrafluoroethylene vascular grafts. The Biotubes could be easily connected to each other without cutting or anastomosis leaks. They could be stored for at least 1 year at room temperature. This study confirmed that even Biotubes formed 1 month after embedding of Biotube Makers had properties comparable to arteries.