Mitochondrial DNA induces nucleus pulposus cell pyroptosis via the TLR9-NF-κB-NLRP3 axis.

BACKGROUND: Nucleus pulposus cell (NPC) death and progressive reduction play important roles in intervertebral disc degeneration (IVDD). As part of a damage-associated molecular pattern, mitochondrial DNA (mtDNA) can be recognized by TLR9 and triggers the expression of NF-κB and NLRP3 inflammasomes, inducing pyroptosis and inflammatory response. However, whether mtDNA induces NPC pyroptosis via the TLR9-NF-κB-NLRP3 axis and promotes IVDD remains uncertain. METHODS: We constructed an in vitro NPC oxidative stress injury model to clarify the mechanism of mtDNA release, TLR9-NF-κB signaling pathway activation, and NPC injury. We further verified the mechanism of action underlying the inhibition of mtDNA release or TLR9 activation in NPC injury in vitro. We then constructed a rat punctured IVDD model to understand the mechanism inhibiting mtDNA release and TLR9 activation in IVDD. RESULTS: We used human NP specimen assays to show that the expression levels of TLR9, NF-κB, and NLRP3 inflammasomes correlated with the degree of IVDD. We demonstrated that mtDNA mediated TLR9-NF-κB-NLRP3 axis activation in oxidative stress-induced human NPC pyroptosis in vitro. Oxidative stress can damage the mitochondria of NPCs, causing the opening of the mitochondrial permeability transition pores (mPTP) and leading to the release of mtDNA into the cytosol. Furthermore, inhibition of mPTP opening or TLR9 activation blocked TLR9-NF-κB-NLRP3 axis activation and thereby mediated NPC pyroptosis and IVDD. CONCLUSION: mtDNA plays a key role in mediating NPC pyroptosis and IVDD via the TLR9-NF-κB-NLRP3 axis. Our findings provide new potential targets for IVDD.

Anti-PD-1 Antibody Administration following Hip Fracture Surgery Reverses Immune Dysfunction and Decreases Susceptibility to Infection.

The aim of this investigation was to assess expression of programmed death-1 (PD-1) and inflammatory status after hip fracture surgery in aged mice and to evaluate the effect of anti-PD-1 antibody intervention. Male C57BL/6 mice aged 22-28 months underwent hip fracture and femoral intramedullary pinning or a sham procedure. Expression of PD-1 was measured on CD4+ and CD8+ T cells. Additionally, the effects of anti-PD-1 antibody on lymphocyte apoptosis, cytokine production, bacterial clearance, and survival were determined. Expression of PD-1 on T cells was upregulated in mice after hip fracture and surgery compared to sham controls. Administration of anti-PD-1 antibody prevented T lymphocyte apoptosis, increased IFN-γ production in splenocytes, and decreased systemic inflammation. Antibody blockade of PD-1 significantly decreased susceptibility to bacteria and improved survival rates of aged mice after hip fracture and surgery followed by the induction of Pseudomonas aeruginosa pneumonia. This study showed that hip fracture and surgical trauma cause significant increases in PD-1 expression in aged mice. Antibody blockade of PD-1 partially reverses T cell apoptosis, decreases the systemic inflammatory response and susceptibility to bacteria, and reduces mortality.

Prognostic Role of Serum Albumin, Total Lymphocyte Count, and Mini Nutritional Assessment on Outcomes After Geriatric Hip Fracture Surgery: A Meta-Analysis and Systematic Review.

BACKGROUND: Hip fracture is a significant health risk for older adults and malnutrition indicates hip fracture risk. METHODS: We evaluated whether nutrition status could predict clinical outcomes and mortality after hip fracture surgery in older adults. MEDLINE, Cochrane, EMBASE, and Google Scholar databases were searched for studies published until July 1, 2018, in patients with serum albumin or total lymphocyte count (TLC) at admission, nutritional status by Mini Nutritional Assessment (MNA), and in-hospital follow-up. Data extracted were analyzed using random-effects or fixed-effects models. RESULTS: Nineteen studies with 34,363 adults aged 74-85 years receiving hip fracture surgery were eligible for inclusion. Among these studies, 13 were screened for low albumin, 4 were evaluated for TLC, and 4 for nutritional status by MNA. Hypoalbuminemia was significantly associated with higher total mortality and higher risk of in-hospital death (both P < .001). Low TLC and MNA results "at risk of malnutrition" (hazard ratio, 1.67; 95% confidence interval = 1.28-2.18) and "malnourished" nutritional status (hazard ratio, 2.65; 95% CI = 1.81-3.88) also were significantly associated with higher total mortality (all P < .001). CONCLUSION: Low serum albumin level is a sole indicator for increased risk of in-hospital death, postoperative complications, and total mortality after hip fracture surgery in older adults. Low TLC and malnutrition classified by MNA predict increased mortality. These indicators provide valuable prognostic information and routine use may be prudent.

Serum miR-146a and miR-150 as Potential New Biomarkers for Hip Fracture-Induced Acute Lung Injury.

BACKGROUND: Acute lung injury (ALI) and subsequent pulmonary infection are the most severe and usually fatal complications for elderly hip fracture patients. It is necessary to find some biomarkers for early diagnosis and prognosis of it. OBJECTIVE: This study is aimed at examining the differential expression of miR-146a, miR-150, and cytokines (IL-6 and IL-10) between younger and elderly rats suffering from hip fracture and investigating the possible meaning of them in early diagnosis and prognosis of ALI after hip fracture. METHODS AND SUBJECTS: Elderly rats and younger rats were randomly divided into sham group and fracture group, respectively. Two fracture groups received hip fracture operations. The damage degree of ALI was evaluated by histological observation and pathological score. Cytokines were measured by ELISA; miR-146a and miR-150 were analysed by qRT-PCR. RESULTS: After treatment, compared with the corresponding sham groups, the pulmonary histological score, the serum miR-146a concentrations, and the cytokine (IL-6 and IL-10) levels in serum and BALF were significantly higher (the miR-150 were lower) in the fracture groups (with the exception of IL-6 of the younger fracture group at 72 h, all P < 0.05). Meanwhile, compared with the younger fracture group, the aforementioned variables were significantly higher (the miR-150 levels were lower) in the elderly fracture group (with the exception of serum IL-10 and pulmonary histological score at 8 h, all P < 0.05). The results of linear regression analysis showed that serum miR-146a and miR-150 were significantly associated with pulmonary histological score. CONCLUSION: Hip fracture can result in significant systemic inflammation and ALI in the rats. Compared to the younger rats, the elderly rats suffered a more remarkable ALI after hip fracture. It may be related to the abnormal expression of miR-146a and miR-150. Serum miR-146a and miR-150 are potential biomarkers for diagnosis and prognosis of ALI after hip fracture.

Incidence of and Factors Influencing Femoral Neck Shortening in Elderly Patients After Fracture Fixation with Multiple Cancellous Screws.

BACKGROUND To study the incidence of and factors influencing "neck shortening" in elderly patients treated for femoral neck fractures using multiple cancellous screws. MATERIAL AND METHODS Of the 197 femoral neck fracture cases treated via closed reduction and cancellous screws fixation from January 2006 to February 2010, 110 were followed up. Patient age, gender, operative time, implantation method, reduction quality, fracture type, bone mineral density, loading time, length of hospital stay, and Harris hip score 12 months after operation were recorded. The patients were divided into two groups (shortening and non-shortening) based on their X-ray performance during follow-up. The healing rates and Harris hip scores of the two groups were compared, and the influencing factors of femoral neck shortening were analyzed. RESULTS Of the 110 cases followed up, 94.5% (104/110) were healed and neck shortening occurred in 41.8% (46/110) within 12.5 months (mean) after treatment. The Harris hip score of the shortening group was lower than that of the non-shortening group (78±17 vs. 86±23, p=0.048). The fracture healing rates of the two groups were not significantly different (p=0.068). The factors influencing neck shortening were significantly correlated with bone mineral density, patient age, gender, and type of fracture. CONCLUSIONS The incidence of neck shortening in elderly patients treated for femoral neck fracture using cancellous screws was high. Bone mineral density, patient age, gender, and type of fracture were the influencing factors of neck shortening.

The Immediate Intramedullary Nailing Surgery Increased the Mitochondrial DNA Release That Aggravated Systemic Inflammatory Response and Lung Injury Induced by Elderly Hip Fracture.

Conventional concept suggests that immediate surgery is the optimal choice for elderly hip fracture patients; however, few studies focus on the adverse effect of immediate surgery. This study aims to examine the adverse effect of immediate surgery, as well as to explore the meaning of mtDNA release after trauma. In the experiment, elderly rats, respectively, received hip fracture operations or hip fracture plus intramedullary nail surgery. After fracture operations, the serum mtDNA levels as well as the related indicators of systemic inflammatory response and lung injury significantly increased in the rats. After immediate surgery, the above variables were further increased. The serum mtDNA levels were significantly related with the serum cytokine (TNF-α and IL-10) levels and pulmonary histological score. In order to identify the meaning of mtDNA release following hip fracture, the elderly rats received injections with mtDNA. After treatment, the related indicators of systemic inflammatory response and lung injury significantly increased in the rats. These results demonstrated that the immediate surgery increased the mtDNA release that could aggravate systemic inflammatory response and lung injury induced by elderly hip fracture; serum mtDNA might serve as a potential biomarker of systemic inflammatory response and lung injury following elderly hip fracture.

Systemic inflammatory responses and lung injury following hip fracture surgery increases susceptibility to infection in aged rats.

Pulmonary infections frequently occur following hip fracture surgery in aged patients. However, the underlying reasons are not fully understood. The present study investigates the systemic inflammatory response and pulmonary conditions following hip fracture surgery as a means of identifying risk factors for lung infections using an aged rodent model. Aged, male Sprague-Dawley rats (8 animals per group) underwent a sham procedure or hip fracture plus femoral intramedullary pinning. Animals were sacrificed 1, 3, and 7 days after the injury. Markers of systemic inflammation and pulmonary injury were analyzed. Both sham-operated and injured/surgical group animals underwent intratracheal inoculation with Pseudomonas aeruginosa 1, 3, and 7 days after surgery. P. aeruginosa counts in blood and bronchoalveolar lavage (BAL) fluid and survival rates were recorded. Serum TNF- α , IL-6, IL-1 ß , and IL-10 levels and markers of pulmonary injury were significantly increased at 1 and 3 days following hip fracture and surgery. Animals challenged with P. aeruginosa at 1 and 3 days after injury had a significantly decreased survival rate and more P. aeruginosa recovered from blood and BAL fluid. This study shows that hip fracture and surgery in aged rats induced a systemic inflammatory response and lung injury associated with increased susceptibility to infection during the acute phase after injury and surgery.

Risk factors and prognosis of postoperative delirium in nonagenarians with hip fracture.

Hip fractures in nonagenarians is one of the great challenges for patients of this age, the family and the larger society. The purpose of this study was to investigate the risk factors and prognosis of postoperative delirium in nonagenarians with hip fracture. 199 Eligible patients were enrolled. Confusion Assessment Method (CAM) were used to identify the delirium. Logistic regressions were used to investigate the effect of 18 pre-existing conditions on postoperative delirium. Prognosis of postoperative delirium in nonagenarians with hip fracture were also be evaluated. The results indicated the following: (1) the prevalence of postoperative delirium among nonagenarians with hip fracture was 28.1% (56 of 199); (2) coexisting disease ≥ 4 (OR = 5.355, 95% CI = 1.394-9.074, P = 0.007), longer admission to operating time (OR = 1.514, 95% CI = 1.247-1.837, P = 0.000), and general anesthesia (OR = 2.086, 95% CI = 1.804-7.968, P = 0.032) were independent risk factors for postoperative delirium in nonagenarians with hip fracture; (3) nonagenarians with postoperative delirium had a predominantly high burden of perioperative complications, long length of stay, and postoperative mortality at 30 days follow-up and 1 year follow-up than the patients without postoperative delirium. The results could enable clinicians to improve outcome after operation in nonagenarians with hip fracture.

Using 3D printing-assisted shaping titanium cages and Masquelet techniques to reconstruct calcaneal osteomyelitis complicated by extensive soft tissue and uncontrolled defects.

OBJECTIVE: To investigate the clinical efficacy of three-dimensional (3D) printing-assisted shaping titanium cage combined with Masquelet technology in the treatment of calcaneal infectious defects. METHODS: A retrospective analysis was performed of the data from nine patients with chronic calcaneal infection defects treated with distal gastronal flap coverage and one patient with free anterolateral thigh flap coverage, also using a 3D printing-assisted shaping titanium cage combined with both mask technology and rib autografting from January 2017 to January 2019. There were seven males and three females, with a mean age of 37 years (range, 17-52 years). The injury mechanism of the 10 patients included four motor vehicle incidents, four high fall injuries, and two rolling compactions. All patients were treated by two⁃stage procedures. The first stage included debridement, polymethyl methacrylate (PMMA) filling, and regional flap coverage. The soft tissue defect of the 10 cases included 80 cm2 in four cases and 56 cm2, 40 cm2, and 15 cm2 in each of two cases. The bone defect was 24 cm3 and 18 cm3 in each of four cases and 3 cm3 in two cases. The second stage was the mask technology of 3D printing-assisted shaping titanium cage combined with rib autografting. Time of bone union, calcaneus morphology, implant position, and the Maryland and AOFAS hind foot scores were recorded to evaluate the clinical outcome. RESULTS: All 10 patients were followed up for a mean of 18.5 months (range, 12-30 months). Infection occurred in two patients 2 months after the first stage operation and were successfully treated by debridement and PMMA replacement. The incision of the other eight cases all healed successfully. Cultures from the 10 cases included five cases of methicillin-resistant Staphylococcus aureus, three cases of S. aureus, and one case each of Escherichia coli and Pseudomonas aeruginosa. All 10 patients exhibited calcaneus bone union after the second stage operation. The mean time for bone union was 4.32 (range, 3-8) months. Bone trabeculae were observed in a CT scan 13 (range, 10-22) months post-operation. The mean Maryland score at 12 months post-operation was 92 (range, 86-98) and the mean AOFAS ankle hind foot score was 89.8 (range, 83-100). CONCLUSION: Three-dimensional printing-assisted shaping titanium cages and Masquelet technology may be effective methods for the treatment of infectious calcaneal defects.

Theoretical Analysis and Numerical Simulation of the Wear of the Sealing Substrate of a High-Pressure, High-Frequency Opening and Closing Hydrogen Ball Valve.

High-pressure valves are an essential infrastructure for hydrogen refueling stations, and the issue of safety and reliability of their operation affects the efficiency of the entire hydrogen delivery system. Hydrogen ball valves are subjected to high-frequency, rapid reciprocating opening and closing for a long time, and the sealing surface between the valve seat and the ball has an uneven wear distribution problem. In this paper, a theoretical derivation of the seat wear volume and wear depth during the hydrogen ball valve adhesive wear process is presented, and a simulation model based on transient dynamics theory is established to carry out a nonlinear finite element analysis of the dynamic contact and frictional wear of the sealing structure during the opening and closing process of the hydrogen ball valve. In order to effectively reduce the wear unevenness of the sealing surface of the ball valve, a new type of valve seat sealing surface with an unequal-width structure is proposed. Comparing the sealing pressure and seat sealing surface wear depth of the ball valve before and after the improvement, the improved ball valve sealing performance is reliable, while the seat sealing surface wear distribution is more uniform.

[Use a leaflet flap of foot to severed multi-finger with segmental injury].

OBJECTIVE: To explore asurgical methods for replantation of severed finger. METHODS: From January 2018 to November 2022, 8 amputated-finger patients were performed surgical reconstructions by using polyfoliate free flaps with the first dorsal metatarsal artery, including 7 males and 1 female, aged from 20 to 55 years old, and defect areas ranged from (1.0 to 2.0) cm×(3.0 to 4.5) cm. Finger pulp sensation, shape and other relevant parameters were assessed following the upper extremity functional evaluation standard, which was put forward by Hand Surgery Branch of Chinese Medical Association. And maryland foot functional score was used to evaluate foot function. RESULTS: Amputated fingers and flaps of all the 8 patients were survived. All patients were followed up for 4 to 20 months, their finger color and temperature tured to normal, with good wear-resistance and cold-resistance. According to Hand Surgery Branch of Chinese Medical Association, functional score ranged 61 to 92;4 patients got excellent result and 4 good. Maryland foot functional score ranged from 93 to 100;and 8 patients got excellent result. CONCLUSION: It is feasible to repair severed fingers with soft tissue defects using polyfoliate free flaps that driven by the flippers of the first and second toes of the foot. This method ccould bridge blood vessels, increase soft tissue volume of the injured finger, and avoid finger shortening, with high patient satisfaction.

[Retracted] Mitochondrial DNA induces inflammation and increases TLR9/NF­κB expression in lung tissue.

Following the publication of this paper, it was drawn to the Editor's attention by a concerned reader that several of the western blotting images shown in Fig. 4 on p. 822 were strikingly similar to data which had appeared in Fig. 5A of the following paper: Fan J, Frey RS and Malik AB: TLR4 signaling induces TLR2 expression in endothelial cells via neutrophil NADPH oxidase. J Clin Invest 112: 1235­1243, 2003. Owing to the fact that the contentious data in the above article had already been published elsewhere prior to its submission to International Journal of Molecular Medicine, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor apologizes to the readership for any inconvenience caused. [International Journal of Molecular Medicine 33: 817­824, 2014; DOI: 10.3892/ijmm.2014.1650].

Clinical Guidelines for the Diagnosis and Treatment of Fragility Fractures of the Pelvis.

BACKGROUND: Fragility fractures of the pelvis (FFPs) are osteoporotic pelvic fractures or insufficiency pelvic fractures caused by the low energy injury or stress fracture in daily livings in the elderly more than 60 years, which the incidence is increasing with the aging population in our country. FFPs result in considerable morbidity and mortality and as well as massive financial burden on the already strained health systems throughout the world. METHODS: This clinical guideline was initiated by the Trauma Orthopedic Branch of Chinese Orthopedic Association; the External Fixation and Limb Reconstruction Branch of Chinese Orthopedic Association; the National Clinical Research Center for Orthopedics, Sports Medicine & Rehabilitation; Senior Department of Orthopedics of Chinese PLA general hospital; the Third Hospital of Hebei Medical University. The grading of recommendations assessment, development and evaluation (GRADE) approach and the reporting items for practice guidelines in healthcare (RIGHT) checklist were adopted. RESULTS: 22 evidence based recommendations were formulated based on 22 most concerned clinical problems among orthopedic surgeons in China. CONCLUSION: Understanding these trends through this guideline will facilitate better clinical care of FFP patients by medical providers and better allocation of resources by policy makers.

[Risk factors and prognosis of preoperative herat failure after hip fracture].

OBJECTIVE: To explore incidence, risk factors and the relationship between preoperative heart failure and prognosis in elderly patients with hip fracture. METHODS: A retrospective analysis was performed on 1 569 elderly patients with hip fracture treated from January 2012 to December 2019, including 522 males and 1 047 females, aged 81.00 (75.00, 90.00) years old;896 intertrochanteric fractures and 673 femoral neck fractures. Patients were divided into heart failure and non-heart failure groups according to whether they developed heart failure before surgery, and heart failure was set as the dependent variable, with independent variables including age, gender, fracture type, comorbidities and hematological indicators, etc. Univariate analysis was performed at first, and independent variables with statistical differences were included in multivariate Logistic regression analysis. Independent risk factors for preoperative heart failure were obtained. The length of hospital stay, perioperative complications, mortality at 30 days and 1 year after surgery were compared between heart failure and non-heart failure groups. RESULTS: There were 91 patients in heart failure group, including 40 males and 51 females, aged 82.00 (79.00, 87.00) years old;55 patients with intertrochanteric fracture and 36 patients with femoral neck fracture. There were 1 478 patients in non-heart failure groups, including 482 males and 996 females, aged 81.00(75.00, 86.00) years old;841 patients with intertrochanteric fracture and 637 patients with femoral neck fracture. There were significant differences in age, sex, coronary heart disease, arrhythmia and dementia between two groups(P<0.05). Multivariate Logistic analysis of statistically significant factors showed that males(OR=1.609, P=0.032), age(OR=1.032, P=0.031), arrhythmia(OR=2.045, P=0.006), dementia (OR=2.106, P=0.014) were independent risk factor for preoperative heart failure. The 30-day and 1-year mortality rates were 9.9% and 26.4% in heart failure group and 3.6% and 13.8% in non-heart failure group, respectively;and had statistical significance between two groups (P<0.05). There were significant differences in pulmonary infection, cerebrovascular complications and cardiovascular complications between two groups (P<0.05). The duration of hospitalization in heart failure group was (16.21±10.64) d compared with that in non-heart failure group (13.26±8.00) d, and the difference was statistically significant (t=2.513, P=0.012). CONCLUSION: Male, old age, arrhythmia and dementia are independent risk factors for heart failure after hip fracture in elderly patients. Patients with preoperative heart failure have a higher incidence of postoperative pulmonary infection, cerebrovascular and cardiovascular complications, higher mortality at 30 d and 1 year after surgery, and longer hospital stay.

Expert consensus on the bone repair strategy for osteoporotic fractures in China.

Osteoporotic fractures, also known as fragility fractures, are prevalent in the elderly and bring tremendous social burdens. Poor bone quality, weak repair capacity, instability, and high failure rate of internal fixation are main characteristics of osteoporotic fractures. Osteoporotic bone defects are common and need to be repaired by appropriate materials. Proximal humerus, distal radius, tibia plateau, calcaneus, and spine are common osteoporotic fractures with bone defect. Here, the consensus from the Osteoporosis Group of Chinese Orthopaedic Association concentrates on the epidemiology, characters, and management strategies of common osteoporotic fractures with bone defect to standardize clinical practice in bone repair of osteoporotic fractures.

Serum lactate concentration on admission to hospital predicts the postoperative mortality of elderly patients with hip fractures 30 days after surgery.

PURPOSE: To determine whether serum lactate concentration on admission to hospital is a predictor for 30-day and 1-year mortality for patients who underwent hip-surgery. METHODS: Data from elderly patients with hip fractures admitted to our hospital (Jan 2012-Dec 2016) were reviewed. The lactate concentration on admission was assessed using a cut-off value of 2.0 mmol/L and then a new cut-off value was determined by maximizing the Youden index. Multivariate logistic regression was employed to verify whether a higher lactate concentration compared with the cutoff value was an independent risk factor for postoperative mortality after 30 days or at 1 year. RESULTS: A total of 1,004 patients were enrolled. There were differences in the incidence of postoperative complications (28.6% vs. 21.9%, P=0.022), length of stay (13.56±8.66 vs. 12.47±7.81 days, P=0.047), 30-day mortality (10.8% vs. 1.3%, P<0.001), 1-year mortality (23.3% vs. 11.8%, P<0.001) and survival time (23.92±16.58 vs. 28.81±16.54 months, P<0.001) between the ≥2.0 mmol/L (n=315) and <2 mmol/L (n=689) groups. Serum lactate concentration was a good predictor of 30-day mortality (AUC=0.829, P<0.001) with a cutoff value of lactate =2.35 mmol/L (sensitivity =0.744, specificity =0.834). Multivariate analysis revealed that a serum lactate concentration ≥2.35 mmol/L at admission was an independent risk factor for 30-day (OR=9.93, P<0.001) and 1-year (OR=2.23, P<0.001) mortality. CONCLUSION: The admission lactate concentration (≥2.35 mmol/L) following hip fracture derived by this study was a significant predictor of mortality 30 days after surgery, which might help physicians to stratify the risk for these patients.

[Therapeutic efficacy of augmentative plate fixation in long-bone hypertrophic nonunion subsequent to intramedullary nailing].

OBJECTIVE: To determine the therapeutic efficacy of augmentation plate fixation in nonunion of long-bone fracture after interlocking intramedullary nailing. METHODS: From April 1998 to April 2009, 14 patients with long-bone hypertrophic nonunion after intramedullary nail internal fixation were treated with augmentative plate. There were nine patients with nonunion of femur, three of humerus and two of tibia. After implanting the intramedullary nail in situ, an augmentative plate fixation was applied to the fracture site to counter the rotational instability. A general plate with at least two screws reaching the opposite cortical bone above and below the fracture was fixated to the lateral side of bone shaft. In all patients, the rotational instability of fracture site was verified intra-operatively in all cases. However, motion disappeared after plate augmentation. RESULTS: All patients achieved radiological solid union at an average of 8 months (range: 6 - 11). Hardware was removed in six cases at 6-11 months post-operation. No infection, hardware loosening or rupture was found. CONCLUSION: The augmentative plate fixation can be applied at the fracture site to prevent the rotational instability. Augmentation plate fixation is indicated for femoral and tibial nonunion of proximal or distal metaphyseal-diaphyseal junctional areas, primary comminuted fracture and humeral nonunion after intramedullary nailing.

Pd-catalyzed C-C cross-coupling reactions within a thermoresponsive and pH-responsive and chelating polymeric hydrogel.

A porous, thermoresponsive and pH-responsive, and chelating hydrogel of poly(N-isopropylacrylamide)-co-poly[2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxypropyl ester] (PNIPAM-co-PMACHE) is proposed as both a reaction medium and the Pd catalyst support for organic synthesis. Organic synthesis within the PNIPAM-co-PMACHE hydrogel has three merits. First, organic reactions such as Suzuki and Heck reactions within the hydrogel can be accelerated due to the enriched Pd catalyst and reactants within the hydrogel by the reversible deswelling/swelling. Second, organic synthesis within the PNIPAM-co-PMACHE hydrogel, which holds about approximately 300 times of water and is similar to the environmentally benign reaction medium of water, can be performed efficiently without surfactant or cosolvent being added. Third, the PNIPAM-co-PMACHE hydrogel itself and the therein-immobilized Pd catalyst can be easily recycled since the hydrogel/Pd composite can reversibly swell/deswell.

Controlled reversible immobilization of Ru carbene on single-walled carbon nanotubes: a new strategy for green catalytic systems based on a solvent effect on pi-pi interaction.

A pyrene-tagged ruthenium carbene 8 was synthesized and immobilized on single-walled carbon nanotubes (SWNTs) via pi-pi stacking. These pi-pi interactions were greatly affected by the reaction temperature and the solvent polarity, thus, offering a new reversible immobilization model that can be controlled by reaction temperature in polar solvents, such as acetone. SWNTs-supported ruthenium carbene 8 is a robust and recyclable catalyst system. Six to seven cycles were achieved for ring-closing metathesis of selected substrates. Importantly, after the complete loss of activity, the SWNTs can be easily recycled by washing with tetrahydrofuran. The recycled SWNTs can then be reloaded with 8. The reusability of the catalyst supported on recycled SWNTs is comparable with that supported on fresh SWNTs.