DSC examination of the rotator cuff muscles in rabbits

Rotator cuff tear is a common musculoskeletal disorder with pathological changes occurring in the structure of the rotator cuff musculature (fatty infiltration). Severe fatty infiltration, observed on MRI or CT scan, negatively influences the result of rotator cuff reconstruction in human beings. The basic histological and biochemical alterations in fatty infiltration of the rotator cuff muscle with torn tendon are still not clear. Differential scanning calorimetric (DSC) examination is a well-established method for the demonstration of thermal consequences of local and global conformational changes in biological systems. With foregoing studies, authors have demonstrated the feasibility of DSC in the investigation of the musculoskeletal system. The aim of this study was to establish the thermograms of the rotator cuff muscles with normal and torn tendons, experimentally induced in rabbits. The DSC results clearly proved that definitive differences are present between the muscles with normal and torn tendons, which have also been demonstrated by MRI and CT scans.     

高频超声分析肩袖病变与肱二头肌长头肌腱病变临床特点及相关性

本文通过高频超声检查分析了肩袖病变与肱二头肌长头肌腱(long head of the biceps brachii tendon,LHBT)病变的临床特点及相关性。文中对32例肩关节镜手术患者的术前肩关节超声检查结果与肩关节镜手术结果进行了一致性检验。按照不同肩袖病变类型对患者进行分组,对组间LHBT病变类型的差异进行了比对分析,并对LHBT病变类型及病变总发生率与肩袖撕裂部位、范围大小均进行了相关性分析。结果证实术前肩关节超声检查结果与关节镜手术结果的诊断一致性中等偏高。LHBT病变类型在不同肩袖撕裂类型中总的差异不显著,而LHBT半脱位在不同肩袖撕裂部位的组间差异较为显著。LHBT病变类型与肩袖撕裂范围大小之间无明显相关性。随着肩袖撕裂范围的增大,LHBT病变发生率升高,二者呈正相关。由本文结果可知,LHBT病变与肩袖病变存在一定相关性,肩袖损伤的早期诊断与修复可防止LHBT病变进一步恶化。     

Application of Nondegradable Synthetic Materials for Tendon and Ligament Injury

Tendon and ligament injuries, prevalent requiring surgical intervention, significantly impact joint stability and function. Owing to excellent mechanical properties and biochemical stability, Nondegradable synthetic materials, including polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE), have demonstrated significant potential in the treatment of tendon and ligament injuries. These above materials offer substantial mechanical support, joint mobility, and tissue healing promotion of the shoulder, knee, and ankle joint. This review conclude the latest development and application of nondegradable materials such as artificial patches and ligaments in tendon and ligament injuries including rotator cuff tears (RCTs), anterior cruciate ligament (ACL) injuries, and Achilles tendon ruptures.     

A reinforced nanofibrous patch with biomimetic mechanical properties and chondroinductive effect for rotator cuff tissue engineering

Patch augmented surgery has been a feasible technique for rotator cuff repair. An ideal rotator cuff tissue engineering patch should have proper mechanical properties to match the native tendons and sufficient biological effect to promote tendon-bone healing. In this study, kartogenin (KGN)-grafted poly (ether-ester-urethane)urea/gelatin composite nanofibrous patches (PEEUU-GEL-KGN) were fabricated via electrospinning process followed by crosslinking of GEL and covalent grafting of KGN. The optimized PEEUU-GEL-KGN nanofibrous patches exhibited biomimetic mechanical properties, including sufficient tensile strength, non-linear stress-strain profiles, and remarkable elasticity and cyclical properties. In vitro investigations revealed that the patches possessed outstanding biocompatibility and performed a sustained release of KGN for a long time. Modification with GEL and KGN significantly improved hydrophilicity of the patches, promoted the adhesion, spreading, and proliferation of mesenchymal stem cells and upregulated the expression of cartilage-related genes. In vivo studies demonstrated that the implanted PEEUU-GEL-KGN patches effectively improved the tissue cellularity and collagen alignment, accelerated the fibrocartilage regeneration, augmented the biomechanical strength of the repaired enthesis, and reinforced the fixing of the tendon to the bone. Overall, the PEEUU-GEL-KGN patches enhanced tendon-bone healing and resisted rotator cuff re-tear. Therefore, the PEEUU-GEL-KGN patch is a highly promising candidate for rotator cuff tissue engineering.     

Changes in thermal denaturation properties of the long head of the biceps during lifetime

Long head of the biceps (LHB) is an intra-articular tendon component of the shoulder joint. The function of this tendon is complex. First, it is an origin of flexion in upper limb, and second it plays role in joint stabilisation during shoulder movements. Histological type of tendon tissues is connective tissue. The mechanical behaviour of connective tissue is primarily determined by the composition and organisation of collagens. In tendons, type I collagen is the principal structural element of the extracellular matrix, which acts to transmit force between bones or bone and muscle. Owing to the special localisation of this tendon, the intra-articular mechanical forces affect it to a considerable extent. The LHB is known as a source of pain in pathologic states of the shoulder joint. The goal of this study was to establish the calorimetric standards of the LHB in different ages, and to observe the changes of thermal properties of collagen during lifetime. LHB samples were taken from 38 cadavers (between ages 0 and 90 years) without macroscopic sign of shoulder pathology. DSC analyses were performed with SETARAM Micro DSC-II. The thermal denaturation parameters varied between T _m (°C): 57, ΔH (J/g): 0.26 (age: 0 year) and T _m (°C): 62.92, ΔH (J/g): 1.28 (age: 90 years). The ageing of collagenous tendon tissue can be clearly followed in changes of thermal denaturation properties. The knowledge of the ageing of normal collagen provides a good basis to analyse further the LHB pathology.     

MSKUS检查对于脑梗后肩周软组织损伤的诊治价值

本文探讨肌骨超声(MSKUS)在诊断脑梗死后并发肩周软组织损伤及指导临床治疗中的价值。选取165例脑梗死后偏瘫并发肩周软组织损伤患者进行临床随机研究,超声指导组83例、常规组82例。经MSKUS检测分析,其中肱二头肌腱病变74例(44.85%)、肩袖病变117例(70.91%)、SA-SD病变48例(29.09%)、肩锁关节病变28例(16.97%);超声指导组在康复治疗2周、康复治疗8周时的VAS评分均显著低于常规组的(P<0.05);超声指导组在康复治疗2周、康复治疗8周时的肩关节前屈活动度、肩关节外展功能活动度均显著大于常规组的(P<0.05);超声指导组在康复治疗8周时的肩关节功能评分均显著大于常规组的(P<0.05)。MSKUS在诊断脑梗死后并发肩周软组织损伤及指导临床治疗中具有重要的价值。     

DSC analysis of human fat tissue in idiopathic avascular necrosis of the femoral head

Avascular necrosis of human femoral head (ANFH) causes incongruity in the joint that leads to disability in patients requires total hip arthroplasty (THA). Several etiological factors of ANFH have been proposed in the literature but there are cases of idiopathic origin. We observed macroscopic variation in quality of the subcutaneous fat tissue in patients with ANFH compared to patients with osteoarthritis or hip fracture during THA procedures.The samples were analysed by histology, gas chromatography (GC) and differential scanning calorimetry (DSC).Conclusion: the alteration in the fatty acid profile did not cause histological changes, however we could detect biochemical changes using DSC and GC.     

DSC analysis of human fat tissue in alcohol-induced avascular necrosis of the femoral head

Avascular necrosis of human femoral head (ANFH) causes incongruity in the joint that leads to disability in patients requires total hip arthroplasty (THA). Several etiological factors of ANFH have been proposed in the literature but there are cases of idiopathic origin. We observed macroscopic variation in quality of the subcutaneous fat tissue in patients with ANFH compared to patients with osteoarthritis or hip fracture during THA procedures. The samples were analysed by histology, gas chromatography (GC) and differential scanning calorimetry (DSC). Conclusion: the alteration in the fatty acid profile did not cause histological changes, however we could detect biochemical changes using DSC and GC.     

Thermal analysis of the cruciate ligaments of the human knee

Summary Cruciate ligaments of the knee joint are important structures very often affected by the degenerative process in case of osteoarthritis. One of the most controversial issues in knee arthroplasty practice nowadays is the role of the posterior cruciate ligament. With foregoing studies authors have demonstrated the feasibility of DSC in the investigation of the musculoskeletal system. With current study authors established the thermal behaviour of healthy cruciate ligaments and detected the alterations in case of osteoarthritis. By establishing the DSC scans of the normal ligaments authors demonstrated clear differences between the posterior and anterior ligament. In addition alterations between normal and arthritic samples could be detected both in terms of changes in total enthalpy and heat capacity. Calorimetric findings have been verified by histological examinations as well.     

Comparison of thermal characteristics of degenerated and inflamed human collagen structures with differential scanning calorimetry

Collagen is the primary structural protein of the human body and the main component of connective tissue. In the form of elongated fibrils, collagen is mostly found in fibrous tissues such as tendon, ligament, and skin. We have already demonstrated that pathologic changes of human collagen structures could be monitored by differential scanning calorimetry (DSC), besides the classical histological methods. The aim of the study was to find whether there is a consistent increase or decrease of the thermal parameters, if we compare the changes of calorimetric enthalpy and denaturation temperature of (1) group: degenerative with (2) group: inflamed collagen structures. The degenerative samples were collected from ruptured Quadriceps, Achilles, patellar and anterior cruciate ligament, and degenerated joint capsule of the shoulder. The inflamed tissue samples were collected from palmar aponeurosis in Dupuytren disease, transverse carpal ligament in carpal tunnel syndrome (CTS), and transverse ligament of the first dorsal compartment in De Quervain disease. The thermal denaturation of human samples was monitored by a SETARAM Micro DSC-II calorimeter. All the experiments were performed between 0 and 100 °C. The heating rate was 0.3 K min^?1. DSC scans clearly demonstrated significant differences between the two groups, proving that the thermal stability of the degenerative and inflamed pathologic collagens is significantly different. In cases of degenerative samples, the enthalpy decreased, while the melting temperature showed an increase. On the contrary, inflamed samples demonstrated a significant increase in the enthalpy and the melting temperature decreased. Our results indicate that DSC may be a clinically relevant method in the diagnosis of different collagen diseases.     

Tendon-bone junction healing by injectable bioactive thermo-sensitive hydrogel based on inspiration of tendon-derived stem cells

The rotator cuff repaired construct must establish a contiguous and functioning tendon-bone junction to provide adequate stability. However, fibrocartilage deficiency and bone loss were hardly reversed after physical suture, especially in chronic rotator cuff tears. In this study, we synthesized an injectable methylcellulose/polyvinyl alcohol/polyvinylpyrrolidone-based thermo-sensitive hydrogel, which delivered kartogenin-loaded mesoporous bioactive glass nanoparticles. Physicochemical studies the revealed phase transition temperatures of 35 °C and its ability to induce chondrogenesis and osteogenesis differentiation of tendon-derived stem cells. Furthermore, experiments in rabbit chronic rotator cuff tears model confirmed the fibrocartilage and bone layer regenerative capability of the injected bioactive hydrogel, which could, in turn, support the ultimate tensile stress of the repaired rotator cuff. The bioactive agents-loaded hydrogel reported in this study is a valuable addition to the arsenal of biomaterials in applications to chronic tendon-bone junction injuries.     

FT-IR microscopic imaging of calcified deposit of rotator cuff tendonitis: A pilot study and a randomised identification of the compositional components after extrusion from tendon to muscle

Fourier transform infrared (FT-IR) microspectroscopy with mapping system was applied to identify and evaluate what difference in the distribution and compositional components of the calcified deposit of rotator cuff tendonitis after dislocation from tendon to muscle. A 49 year-old female patient suffered from severe shoulder pain was enrolled in this study. Diagnostic high-resolution ultrasonography (HRUS) was initially carried out to verify the calcific tendonitis. The calcified deposits were then examined by histopathologic assessment and FT-IR microspectroscopy. Diagnostic HRUS reveals that the calcified deposits were observed in the subscapularis tendon and infraspinatus muscle of the shoulder for this patient. FT-IR microspectroscopic imaging results clearly indicate that both IR spectra of the calcified deposits in tendon and muscle were almost the same as that of the IR spectrum of hydroxyapatite except the peak at 873 cm⁻¹. It is also found that the peak intensity at 1030 cm⁻¹ for tendon sample was somewhat more intense than that of the peak at 1031 cm⁻¹ for muscle sample, implying that the calcified sample in the tendon seems to be mature than that in the muscle. The second-derivative IR spectra of two calcified samples exhibit two specific sharp peaks at 880 and 872 cm⁻¹, indicating that the type A and type B carbonated apatites were markedly co-existed in both calcified deposits of tendon and muscle even the calcified deposit was dislocated from tendon to muscle. These carbonated apatites presented in the calcified deposits of either tendon or muscle of the shoulder were also consistent with the nodular or nodular nodular-cystic morphology of calcified plaque of the shoulder after HRUS examination.     

Thermal analysis of the osteoarthritic human hyaline cartilage

Summary Arthritis of major joints, especially osteoarthritis of the knee is a very frequent disease of human beings mainly in the developed countries. The pathology of osteoarthritis has been subject of many publications before, using a wide spectrum of different methods to evaluate degenerative changes of hyaline cartilage. The authors examined osteoarthritic human knee joint hyaline cartilage with differential scanning calorimetry. The different stages of cartilage degeneration have been verified by histological examinations. The research group demonstrated thermal differences between various stages of osteoarthritis. Besides explaining possible causes for experienced thermodynamic effects, the authors reflect upon future research ways and the possibilities of applying the method in practice.     

Crystallization behaviors of n-nonadecane in confined space: observation of metastable phase induced by surface freezing

Crystallization and phase transition behaviors of n-nonadecane in microcapsules with a diameter of about 5 mum were studied with the combination of differential scanning calorimetry (DSC) and synchrotron radiation X-ray diffraction (XRD). As evident from the DSC measurement, a surface freezing monolayer, which is formed in the microcapsules before the bulk crystallization, induces a novel metastable rotator phase (R(II)), which has not been reported anywhere else. We argue that the existence of the surface freezing monolayer decreases the nucleating potential barrier of the R(II) phase and induces its appearance, while the lower free energy in the confined geometry turns the transient R(II) phase to a "long-lived" metastable phase.     

热处理对尼龙1010固态结晶和玻璃态热松驰的影响

本文用DSC首先论证淬火尼龙1010试样在DSC曲线上出现的放热峰是冷结晶峰,然后研究淬火尼龙1010在不同热处理条件下,冷结晶峰和玻璃态热松驰峰的变化规律。实验结果表明,等温结晶时间较短,试样的固态结晶速率较快;等温结晶时间较长,固态结晶速率较慢,这可能与在Tg区域等温所形成的新氢键有关。当升高等温温度时,固态结晶速率加快。在低于Tg的不同温度退火,玻璃态热松弛峰的峰高及热焓在281K达最大值,进而确定对玻璃态热松驰影响最敏感的温度区间是277～284K。     

Studies on the Crystallization Behavior of Polypropylene Solid Phase Grafted Maleic Anhydride

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Use of DSC and DMA to study crystallization as a possible cause for a glove tear

The Advanced Crew Escape Suit (ACES) is a pressurized suit worn by astronauts during launch and landing phases of Space Shuttle operations. In 2008, a large tear (12.7–25.4 mm long, between the pinky and ring finger) in the ACES left-hand glove made of neoprene latex rubber was found during training for Shuttle flight STS-124. An investigation to help determine the cause(s) of the glove tear was headed by the NASA Johnson Space Center (JSC) in Houston, Texas. Efforts at JSC to reproduce the actual glove tear pattern by cutting/tearing or rupturing were unsuccessful. Chemical and material property data from JSC such as GC-MS, FTIR, DSC, and TGA mostly showed little differences between samples from the torn and control gloves. One possible cause for the glove tear could be a wedding ring/band worn by an astronaut. Even with a smooth edge, such a ring could scratch the material and initiate the tear observed in the left-hand glove. A decision was later made by JSC to not allow the wearing of such a ring during training or actual flight. Another possible cause for the ACES glove tear is crystallinity induced by strain in the neoprene rubber over a long period of time and use. Neoprene is one among several elastomers known to be susceptible to crystallization, and such a process is accelerated with exposure of the material to cold temperatures plus strain. When the temperature is lowered below room temperature, researchers have shown that neoprene crystallization may be maintained at temperatures as high as 7.2–10 °C, with a maximum crystallization rate near −6.7 to −3.9 °C (Kell et al. J Appl Polym Sci 2(4):8–13, 1959 [1]). A convenient conditioning temperature for inducing neoprene crystallization is a typical freezer that is held near −17.8 °C. For work at the NASA Marshall Space Flight Center (MSFC), samples were cut from several areas/locations (pinky/ring finger crotch, index finger and palm) on each of two pairs of unstrained ACES gloves for DSC and DMA thermal analysis testing. The samples were conditioned in a freezer for various times up to about 14 days. Some rectangular conditioned samples were unstrained, while most were subjected to strains up to 250% with the aid of two slotted aluminum blocks and two aluminum clamps per sample. Trends were observed to correlate DSC data (heat of fusion) and DMA data (linear CTE and stress for iso-strain testing) with (a) sample location on each glove; and (b) percent strain during conditioning. Control samples cut “as is” from each glove location were also tested by DSC and DMA.     

单取代二茂铁有机液晶的合成、结构及刚性实对介晶性影响

合成了17个未见报道的中心桥连基为酯基、C==N基,分别含有3-4个苯环,不同刚性实长度以及不同末端链长度的二茂铁化合物,并通过DSC和偏光显微镜对其介晶性进行了表征.研究表明,末端长度对相变温度和清亮温度均有影响,但对相变温度范围影响较小,而刚性实长度对其影响却很大.当刚性实达到一定长度时,末端为H原子也具有介晶性---这是第一个无柔性末端链的金属有机液晶化合物.     

Hydration kinetics of tricalcium silicate by calorimetric methods

The kinetics of the cement hydration reaction is a relevant issue in the cement research field, particularly in the presence of additional inorganic and organic components that consistently increase the complexity of the cement paste. In the present study, the hydration reaction of pure tricalcium silicate has been monitored by different calorimetric approaches: the conventional Isothermal Conduction Calorimetry (IC) and a novel Differential Scanning Calorimetry (DSC) protocol. The measured hydration curves have been modeled by using the Boundary Nucleation and Growth Model (BNGM) to extract thermodynamic parameters of the early stages of the hydration reaction. IC and DSC methods provide similar results in terms of rate constants, linear growth, and nucleation rates even though the IC accesses the total evolved heat while DSC discloses the fraction of unreacted water. The validation of the DSC approach as a reliable analytical method to the study of cement hydration kinetic is of particular importance because it allows following very long hydration processes, such as those of pastes containing organic retarders or superplasticizers. The thermodynamic and kinetic parameters for the tricalcium silicate setting has been also evaluated and discussed as a function of the surface area of the powder.     

Application of the differential scanning calorimeter to purity measurements

This paper presents a new method for the calculation of the purity of organic, non-polymeric samples using the recorder trace from a Differential Scanning Calorimeter (DSC), Perkin-Elmer Corp. The entire DSC recorder trace is employed rather than only the initial portion of the curve. The previous trial and error choice of energy lost by the DSC trace has been replaced by a definite numerical value. Meaningful purity values have been obtained from a single DSC trace on samples of from 95 to 99.9% purity. This new method has been demonstrated to provide more accurate and less ambiguous results than the manufacturer's procedure.