A novel membrane targeting domain mediates the endosomal or Golgi localization specificity of small GTPases Rab22 and Rab31.

Rab22 and Rab31 belong to the Rab5 subfamily of GTPases that regulates endocytic traffic and endosomal sorting. Rab22 and Rab31 (a.k.a. Rab22b) are closely related and share 87% amino acid sequence similarity, but they show distinct intracellular localization and function in the cell. Rab22 is localized to early endosomes and regulates early endosomal recycling, while Rab31 is mostly localized to the Golgi complex with only a small fraction in the endosomes at steady state. The specific determinants that affect this differential localization, however, are unclear. In this study, we identify a novel membrane targeting domain (MTD) consisting of the C-terminal hypervariable domain (HVD), interswitch loop (ISL), and N-terminal domain as a major determinant of endosomal localization for Rab22 and Rab31, as well as Rab5. Rab22 and Rab31 share the same N-terminal domain, but we find Rab22 chimeras with Rab31 HVD exhibit phenotypic Rab31 localization to the Golgi complex, while Rab31 chimeras with the Rab22 HVD localize to early endosomes, similar to wildtype Rab22. We also find that the Rab22 HVD favors interaction with the early endosomal effector protein Rabenosyn-5, which may stabilize the Rab localization to the endosomes. The importance of effector interaction in endosomal localization is further demonstrated by the disruption of Rab22 endosomal localization in Rabenosyn-5 knockout cells and by the shift of Rab31 to the endosomes in Rabenosyn-5-overexpressing cells. Taken together, we have identified a novel MTD that mediates localization of Rab5 subfamily members to early endosomes via interaction with an effector such as Rabenosyn-5.

Bacillus anthracis spores are internalized in human lung epithelial cells by Rab GTPase-supported macropinocytosis.

Inhalation anthrax, the deadliest form of the disease, requires inhaled B. anthracis spores to escape from the alveolar space and travel to the mediastinal lymph nodes, from where the vegetative form of the pathogen disseminates, resulting in a rapidly fatal outcome. The role of epithelia in alveolar escape is unclear, but previous work suggests these epithelial cells are involved in this process. Using confocal microscopy, we found that B. anthracis spores are internalized more rapidly by A549 type II alveolar epithelial cells compared to hAELVi type I alveolar epithelial cells. Internalization of spores by alveolar epithelial cells requires cytoskeletal rearrangement evidenced by significant inhibition by cytochalasin D, an actin inhibitor. Chemical inhibitors of macropinocytosis significantly downregulated B. anthracis spore internalization in human alveolar cells, while inhibitors of other endocytosis pathways had minimal effects. Additional studies using a macropinosome marker and electron microscopy confirmed the role of macropinocytosis in spore uptake. By colocalization of B. anthracis spores with four endocytic Rab proteins, we demonstrated that Rab31 played a role in B. anthracis spore macropinocytosis. Finally, we confirmed that Rab31 is involved in B. anthracis spore internalization by enhanced spore uptake in Rab31-overexpressing A549 cells. This is the first report that shows B. anthracis spore internalization by macropinocytosis in human epithelial cells. Several Rab GTPases are involved in the process.

[Deep Learning-Based Identification of Common Complication Features of Surgical Incisions].

Objective: In recent years, due to the development of accelerated recovery after surgery and day surgery in the field of surgery, the average length-of-stay of patients has been shortened and patients stay at home for post-surgical recovery and healing of the surgical incisions. In order to identify, in a timely manner, the problems that may appear at the incision site and help patients prevent or reduce the anxiety they may experience after discharge, we used deep learning method in this study to classify the features of common complications of surgical incisions, hoping to realize patient-directed early identification of complications common to surgical incisions. Methods: A total of 1 224 postoperative photographs of patients' surgical incisions were taken and collected at a tertiary-care hospital between June 2021 and March 2022. The photographs were collated and categorized according to different features of complications of the surgical incisions. Then, the photographs were divided into training, validation, and test sets at the ratio of 8∶1∶1 and 4 types of convolutional neural networks were applied in the training and testing of the models. Results: Through the training of multiple convolutional neural networks and the testing of the model performance on the basis of a test set of 300 surgical incision images, the average accuracy of the four ResNet classification network models, SE-ResNet101, ResNet50, ResNet101, and SE-ResNet50, for surgical incision classification was 0.941, 0.903, 0.896, and 0.918, respectively, the precision was 0.939, 0.898, 0.868, and 0.903, respectively, and the recall rate was 0.930, 0.880, 0.850, and 0.894, respectively, with the SE-Resnet101 network model showing the highest average accuracy of 0.941 for incision feature classification. Conclusion: Through the combined use of deep learning technology and images of surgical incisions, problematic features of surgical incisions can be effectively identified by examining surgical incision images. It is expected that patients will eventually be able to perform self-examination of surgical incisions on smart terminals.

Class IA PI3K p110ß subunit promotes autophagy through Rab5 small GTPase in response to growth factor limitation.

Autophagy is an evolutionarily conserved membrane trafficking process. Induction of autophagy in response to nutrient limitation or cellular stress occurs by similar mechanisms in organisms from yeast to mammals. Unlike yeast, metazoan cells rely more on growth factor signaling for a wide variety of cellular activities including nutrient uptake. How growth factor availability regulates autophagy is poorly understood. Here we show that, upon growth factor limitation, the p110ß catalytic subunit of the class IA phosphoinositide 3-kinases (PI3Ks) dissociates from growth factor receptor complexes and increases its interaction with the small GTPase Rab5. This p110ß-Rab5 association maintains Rab5 in its guanosine triphosphate (GTP)-bound state and enhances the Rab5-Vps34 interaction that promotes autophagy. p110ß mutants that fail to interact with Rab5 are defective in autophagy promotion. Hence, in mammalian cells, p110ß acts as a molecular sensor for growth factor availability and induces autophagy by activating a Rab5-mediated signaling cascade.

Ehrlichia type IV secretion system effector Etf-2 binds to active RAB5 and delays endosome maturation.

Ehrlichia chaffeensis, an obligatory intracellular bacterium, infects monocytes/macrophages by sequestering a regulator of endosomal traffic, the small GTPase RAB5, on its membrane-bound inclusions to avoid routing to host-cell phagolysosomes. How RAB5 is sequestered on ehrlichial inclusions is poorly understood, however. We found that native Ehrlichia translocated factor-2 (Etf-2), a previously predicted effector of the Ehrlichia type IV secretion system, and recombinant Etf-2 (cloned into the Ehrlichia genome) are secreted into the host-cell cytoplasm and localize to ehrlichial inclusions. Ectopically expressed Etf-2-GFP also localized to inclusions and membranes of early endosomes marked with RAB5 and interacted with GTP-bound RAB5 but not with a GDP-bound RAB5. Etf-2, although lacking a RAB GTPase-activating protein (GAP) Tre2-Bub2-Cdc16 (TBC) domain, contains two conserved TBC domain motifs, namely an Arg finger and a Gln finger, and site-directed mutagenesis revealed that both Arg188 and Gln245 are required for Etf-2 localization to early endosomes. The yeast two-hybrid assay and microscale thermophoresis revealed that Etf-2 binds tightly to GTP-bound RAB5 but not to GDP-bound RAB5. However, Etf-2 lacks RAB5-specific GAP activity. Etf-2 localized to bead-containing phagosomes as well as endosomes containing beads coated with the C-terminal fragment of EtpE (entry-triggering protein of Ehrlichia), an Ehrlichia outer-membrane invasin, and significantly delayed RAB5 dissociation from and RAB7 localization to phagosomes/endosomes and RABGAP5 localization to endosomes. Thus, binding of Etf-2 to RAB5-GTP appears to delay RAB5 inactivation by impeding RABGAP5 localization to endosomes. This suggests a unique mechanism by which RAB5 is sequestered on ehrlichial inclusions to benefit bacterial survival and replication.

The Protein Tyrosine Phosphatase MEG2 Regulates the Transport and Signal Transduction of Tropomyosin Receptor Kinase A.

Protein tyrosine phosphatase MEG2 (PTP-MEG2) is a unique nonreceptor tyrosine phosphatase associated with transport vesicles, where it facilitates membrane trafficking by dephosphorylation of the N-ethylmaleimide-sensitive fusion factor. In this study, we identify the neurotrophin receptor TrkA as a novel cargo whose transport to the cell surface requires PTP-MEG2 activity. In addition, TrkA is also a novel substrate of PTP-MEG2, which dephosphorylates both Tyr-490 and Tyr-674/Tyr-675 of TrkA. As a result, overexpression of PTP-MEG2 down-regulates NGF/TrkA signaling and blocks neurite outgrowth and differentiation in PC12 cells and cortical neurons.

Distinct biochemical and functional properties of two Rab5 homologs from the rice blast fungus Magnaporthe oryzae.

Rab5 is a key regulator of early endocytosis by promoting early endosomal fusion and motility. In this study, we have unexpectedly found distinct properties of the two Rab5 homologs (MoRab5A and MoRab5B) from Magnaporthe oryzae, a pathogenic fungus in plants whose infection causes rice blast disease. Like mammalian Rab5, MoRab5A and MoRab5B can bind to several Rab5 effectors in a GTP-dependent manner, including EEA1, Rabenosyn-5, and Rabaptin-5. However, MoRab5A shows distinct binding characteristics in the sense that both the wild-type and the GTP hydrolysis-defective constitutively active mutant bind the effectors equally well in GST pull-down assays, suggesting that MoRab5A is defective in GTP hydrolysis and mostly in the GTP-bound conformation in the cell. Indeed, GTP hydrolysis assays indicate that MoRab5A GTPase activity is dramatically lower than MoRab5B and human Rab5 and is insensitive to RabGAP5 stimulation. We have further identified a Pro residue in the switch I region largely responsible for the distinct MoRab5A properties by characterization of MoRab5A and MoRab5B chimeras and mutagenesis. The differences between MoRab5A and MoRab5B extend to their functions in the cell. Although they both target to early endosomes, only MoRab5B closely resembles human Rab5 in promoting early endosome fusion and stimulating fluid phase endocytosis. In contrast, MoRab5A correlates with another related early endosomal Rab, Rab22, in terms of the presence of the switch I Pro residue and the blocked GTPase activity. Our data thus identify MoRab5B as the Rab5 ortholog and suggest that MoRab5A specializes to perform a non-redundant function in endosomal sorting.

Interaction at the silicon/transition metal oxide heterojunction interface and its effect on the photovoltaic performance.

The interfacial reaction and energy level alignment at the Si/transition metal oxide (TMO, including MoO3-x, V2O5-x, WO3-x) heterojunction are systematically investigated. We confirm that the interfacial reaction appears during the thermal deposition of TMO, with the reaction extent increasing from MoO3-x, to V2O5-x, and to WO3-x. The reaction causes the surface oxidation of silicon for faster electron/hole recombination, and the reduction of TMO for effective hole collection. The photovoltaic performance of the Si/TMO heterojunction devices is affected by the interface reaction. MoO3-x are the best hole selecting materials that induce least surface oxidation but strongest reduction. Compared with H-passivation, methyl group passivation is an effective way to reduce the interface reaction and improve the interfacial energy level alignment for better electron and hole collection.

Worldwide Research Productivity in the Field of Arthroscopy: A Bibliometric Analysis.

PURPOSE: This study aimed to evaluate the quantity and quality of articles from different countries involving arthroscopy to investigate the characteristics of worldwide research productivity. METHODS: Web of Science was searched for arthroscopy articles published between 1999 and 2013. The numbers of articles and citations were analyzed to assess the contributions of different countries. Publication activity was adjusted by country population and gross domestic product (GDP). RESULTS: A total of 12,553 articles were published worldwide. The time trend for the number of articles showed an increase of 2.27-fold between 1999 and 2013. North America, Western Europe, and Eastern Asia were the most productive areas. High-income countries published 90.86% of the articles; middle-income countries, 9.11%; and lower-income countries, only 0.02%. The United States published the most articles (35.40%), followed by Germany (9.53%), the United Kingdom (6.80%), the Republic of Korea (5.45%), and Japan (4.76%), and had the highest total citations (78,161). However, Sweden had the highest mean citations (35.56), followed by Switzerland (23.39) and the Netherlands (18.90). There were positive correlations between the number of publications and population/GDP (P < .01). When normalized to population, Switzerland ranked the highest, followed by Finland and Sweden. When adjusted by GDP, the Republic of Korea ranked first, followed by Finland and Turkey. CONCLUSIONS: The number of publications on arthroscopy increased significantly from 1999 to 2013, with a more than 2-fold increase in volume. The United States was the most productive country as measured by total publications, but when adjusted for population, Switzerland published the highest number of articles, followed by Finland and Sweden. When publications were adjusted for GDP, the Republic of Korea ranked first, with Finland second and Turkey third. CLINICAL RELEVANCE: Bibliometric analysis allows us to understand contributions of different world regions in scientific research in the field of arthroscopy and gives insight into the quantity and quality of articles related to arthroscopy.

Asialoglycoprotein receptor 1 promotes SARS-CoV-2 infection of human normal hepatocytes.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes multi-organ damage, which includes hepatic dysfunction, as observed in over 50% of COVID-19 patients. Angiotensin I converting enzyme (peptidyl-dipeptidase A) 2 (ACE2) is the primary receptor for SARS-CoV-2 entry into host cells, and studies have shown the presence of intracellular virus particles in human hepatocytes that express ACE2, but at extremely low levels. Consequently, we asked if hepatocytes might express receptors other than ACE2 capable of promoting the entry of SARS-CoV-2 into cells. To address this question, we performed a genome-wide CRISPR-Cas9 activation library screening and found that Asialoglycoprotein receptor 1 (ASGR1) promoted SARS-CoV-2 pseudovirus infection of HeLa cells. In Huh-7 cells, simultaneous knockout of ACE2 and ASGR1 prevented SARS-CoV-2 pseudovirus infection. In the immortalized THLE-2 hepatocyte cell line and primary hepatic parenchymal cells, both of which barely expressed ACE2, SARS-CoV-2 pseudovirus could successfully establish an infection. However, after treatment with ASGR1 antibody or siRNA targeting ASGR1, the infection rate significantly dropped, suggesting that SARS-CoV-2 pseudovirus infects hepatic parenchymal cells mainly through an ASGR1-dependent mechanism. We confirmed that ASGR1 could interact with Spike protein, which depends on receptor binding domain (RBD) and N-terminal domain (NTD). Finally, we also used Immunohistochemistry and electron microscopy to verify that SARS-CoV-2 could infect primary hepatic parenchymal cells. After inhibiting ASGR1 in primary hepatic parenchymal cells by siRNA, the infection efficiency of the live virus decreased significantly. Collectively, these findings indicate that ASGR1 is a candidate receptor for SARS-CoV-2 that promotes infection of hepatic parenchymal cells.

Long-term administration of probiotics prevents gastrointestinal mucosal barrier dysfunction in septic mice partly by upregulating the 5-HT degradation pathway.

Sepsis can impair gastrointestinal (GI) barrier integrity. Oral probiotics (PT) can maintain the balance of GI microflora and improve GI function. 5-Hydroxytryptamine (5-HT) is a key promoter of GI injury caused by sepsis. However, the mechanism by which PT attenuates sepsis by regulating 5-HT is not fully understood. In this study, C57BL6 mice were intragastric administrated with normal saline (NC) or PT once a day for 4 weeks before cecal ligation and puncture (CLP). Compared with NC-CLP mice, PT-CLP mice had lower clinical score, higher body temperature. The survival rate of PT-CLP mice was significantly improved. The levels of inflammatory cytokines and 5-HT were obviously decreased in PT-CLP mice, and GI peristalsis and barrier function were enhanced. Moreover, sepsis downregulated the expression of tight junction proteins, while PT pretreatment could maintain them at the level of sham operation group. Furthermore, PT pretreatment increased the expression of serotonin transporter and monoamine oxidase A. PT administration could inhibit NF-κB activity, and activate ERK activity. In conclusion, long-term supplementation of PT before CLP can prevent sepsis-induced GI mucosal barrier dysfunction in mice, which may be partially mediated by upregulating the 5-HT degradation pathway via activating ERK signaling.

Pharmacokinetic and Bioequivalence Evaluation of Two Cefprozil Dispersible Tablets in Healthy Chinese Volunteers.

This study aimed to assess the bioequivalence of 2 cefprozil dispersible tablet formulations (250 mg) in healthy Chinese volunteers under fasting and fed conditions and to determine the pharmacokinetics of cefprozil. A randomized, single-dose, open-label, 2-formulation, 2-period study was conducted. The elimination period for this study was 7 days. Forty-eight healthy volunteers received 250-mg cefprozil dispersible tablets in each study period under both test and reference conditions. The test and the reference cefprozil were bioequivalent in healthy Chinese volunteers, and there was no significant food effect in individuals receiving either formulation. No serious adverse event was recorded, and no volunteers withdrew from the study.

Effect of Alloying Powders on Microstructure and Mechanical Properties of Aluminum Alloy Arc Additive Manufacturing.

Cold metal transfer arc additive manufacturing technique was used to produce 5356 aluminum alloy by adding refining agents to solve the problems of coarse grains and poor performance. Metallic powders (Ti, TiH, and Ti+B4C) were used to refine the grain size and promote the mechanical properties of the alloy. The effects of refining agents on the microstructure and mechanical properties of straight wall samples (SWSs) were studied. Samples with Ti+B4C addition had a profound impact on morphology. However, the TiH added sample revealed uneven transition between sediment layers, unstable precipitation process, unstable wall height and wall width, poor morphology, and defects. All SWSs with powder addition revealed the formation of the Al3Ti phase. Moreover, the columnar grains between the layers were transformed into equiaxed grains and finer grains at the center of the layers. There was a significant effect of TiH on the grain refinement. The samples with Ti demonstrated superior mechanical properties. The tensile strength and elongation of the SWSs increased by 28 MPa and 4.6% in the parallel additive direction and by 37 MPa and 8.9% in the vertical direction. The addition of Ti also contributed to the even distribution of the mechanical properties in both directions.

PTPN18 Stimulates the Development of Ovarian Cancer by Activating the PI3K/AKT Signaling.

Objective: To illustrate the functions of protein tyrosine phosphatase nonreceptor type 18 (PTPN18) in the progression of ovarian cancer and the potential molecular mechanism. Methods: Differential PTPN18 expression in ovarian cancer samples was determined. Following PTPN18 knockdown, changes in proliferation and migration in ovarian cancer cells were detected. Nude mice with ovarian cancer were used to uncover the effects of PTPN18 on ovarian cancer growth in vivo. Results: PTPN18 was significantly upregulated in ovarian cancer samples and linked to pathological staging and metastasis rate. PTPN18 displayed prognostic and diagnostic potentials in ovarian cancer. Knockdown of PTPN18 and treatment of the PI3K inhibitor could inhibit proliferative and migratory abilities in ovarian cancer cells. Moreover, PTPN18 was capable of inactivating PI3K/AKT signaling. In vivo knockdown of PTPN18 suppressed ovarian cancer growth in nude mice. Conclusions: PTPN18 is upregulated in ovarian cancer, which stimulates the malignant development by activating PI3K/AKT signaling. The PTPN18 level is also associated with pathological staging and metastasis in ovarian cancer patients, which may be utilized as a hallmark predicting the malignant level.

FBXO34 promotes latent HIV-1 activation by post-transcriptional modulation.

ABSTRACTAcquired immunodeficiency syndrome (AIDS) cannot be completely cured, mainly due to the existence of a latent HIV-1 reservoir. However, our current understanding of the molecular mechanisms underlying the establishment and maintenance of HIV-1 latent reservoir is not comprehensive. Here, using a genome-wide CRISPR-Cas9 activation library screening, we identified E3 ubiquitin ligase F-box protein 34 (FBXO34) and the substrate of FBXO34, heterogeneous nuclear ribonucleoprotein U (hnRNP U) was identified by affinity purification mass spectrometry, as new host factors related to HIV-1 latent maintenance. Overexpression of FBXO34 or knockout of hnRNP U can activate latent HIV-1 in multiple latent cell lines. FBXO34 mainly promotes hnRNP U ubiquitination, which leads to hnRNP U degradation and abolishment of the interaction between hnRNP U and HIV-1 mRNA. In a latently infected cell line, hnRNP U interacts with the ReV region of HIV-1 mRNA through amino acids 1-339 to hinder HIV-1 translation, thereby, promoting HIV-1 latency. Importantly, we confirmed the role of the FBXO34/hnRNP U axis in the primary CD4+ T lymphocyte model, and detected differences in hnRNP U expression levels in samples from patients treated with antiretroviral therapy (ART) and healthy people, which further suggests that the FBXO34/hnRNP U axis is a new pathway involved in HIV-1 latency. These results provide mechanistic insights into the critical role of ubiquitination and hnRNP U in HIV-1 latency. This novel FBXO34/hnRNP U axis in HIV transcription may be directly targeted to control HIV reservoirs in patients in the future.

Similar Efficacy of Arthroscopy and Arthrotomy in Infection Eradication in the Treatment of Septic Knee: A Systematic Review and Meta-Analysis.

Aim: To compare the arthroscopy vs. arthrotomy for the treatment of native knee septic arthritis. Methods: Electronic databases of PubMed, Embase and Cochrane Library were searched for eligible studies. Retrospective comparative studies comparing arthroscopy or arthrotomy for patients with septic arthritis of the native knee were eligible for this review. The primary outcome was recurrence of infection after first procedure. The secondary outcomes included hospital length of stay, operative time, range of motion of the involved knee after surgery, overall complications and mortality rate, Results: Thirteen trials were included in this study. There were a total of 2,162 septic arthritis knees treated with arthroscopic debridement and irrigation, and 1,889 septic arthritis knees treated with open debridement and irrigation. Arthroscopy and arthrotomy management of the knee septic arthritis showed comparable rate of reinfection (OR = 0.85; 95% CI, 0.57-1.27; P = 0.44). No significant difference was observed in hospital length of stay, operative time and mortality rate between arthroscopy and arthrotomy management group, while arthroscopy treatment was associated with significantly higher knee range of motion and lower complication rate when compared with arthrotomy treatment. Conclusion: Arthroscopy and arthrotomy showed similar efficacy in infection eradication in the treatment of native septic knee. However, arthroscopy treatment was associated with better postoperative functional recovery and lower complication rate.

Mist1 promoted inflammation in colitis model via K+-ATPase NLRP3 inflammasome by SNAI1.

Ulcerative colitis (UC) is a chronic inflammatory intestinal disease. Genetic susceptibility, gut microbiota and mucosal immune dysfunction play important roles in the pathogenesis and development of UC. We investigate the effect of Mist1 in model of colitis and its underlying mechanism. The expressions of Mist1 in patients with colitis tissue were up-regulated. Meanwhile, Mist1 mRNA and protein expressions in DSS-induced colitis mice model were also induced and Mist1 mRNA and protein expressions of LPS induced THP-1 cell were also up-regulated. we found Mist1 human protein promoted inflammation in DSS-induced colitis mice by NLRP3. So, we up-regulated Mist1 expression and over-expression of Mist1 promoted IL-1ß and NLRP3 protein expression levels in vitro model. However, down-regulation of Mist1 suppressed IL-1ß and NLRP3 protein expression levels in vitro model. Next, SNAI1 is a shooting point of Mist1 in the effects of Mist1 in colitis. The inhibition of SNAI1 reduced the effects of Mist1 on NLRP3 inflammasome in vitro model. Activation of SNAI1 induced the effects of Mist1 on NLRP3 inflammasome in vitro model. Lastly, anti-SNAI1 human protein lowered the effects of Mist1 human protein on NLRP3 inflammasome in DSS-induced colitis mice. We demonstrated that Mist1 promoted inflammation in colitis model via NLRP3 inflammasome by SNAI1, whereas the absence of these macrophages led to a significant improvement in colitis treatment.

[Morphological analysis of coronal femoral intertrochanteric fracture and its effect on reduction and internal fixation].

OBJECTIVE: To investigate the morphology of coronal femoral intertrochanteric fracture and its effect on reduction and internal fixation. METHODS: The clinical and imaging data of 46 patients with femoral intertrochanteric fracture who met the selection criteria between August 2017 and October 2018 were reviewed. There were 15 males and 31 females; the age ranged from 62 to 91 years, with an average of 72.8 years. The causes of injury included walking falls in 35 cases, falling out of bed in 4 cases, and traffic accidents in 7 cases. The AO/Orthopaedic Trauma Association classification was type 31-A1 in 11 cases and type 31-A2 in 35 cases. All patients underwent closed reduction and internal fixation with intramedullary nails. During the operation, fracture reduction and fixation were performed according to the preoperative evaluation results. According to the patients' preoperative X-ray film and CT three-dimensional reconstruction images, the direction of the coronal fracture line of the femoral intertrochanter and the morphological characteristics of the fracture block were observed; and the coronal fracture discrimination analysis was carried out for the fractures of different AO/OTA types. The percentages of coronal femoral intertrochanteric fractures diagnosed by preoperative X-ray film and CT three-dimensional reconstruction were calculated and statistically analyzed. The fracture reduction, the position of internal fixation [measurement of tip-apex distance (TAD)]. and the reliability of internal fixation were observed after operation. RESULTS: X-ray film was not easy to identify coronary fracture, and the coronal fracture line and the shape of the fracture piece weree clearly visible in CT three-dimensional reconstruction images. The morphological characteristics of the coronary fracture block: in AO/OTA 31-A1 type, the fracture line extended obliquely backward from the anterior tip of the large rotor, above the small rotor with or without small rotor fracture; in AO/OTA 31-A2 type, fracture line extended obliquely backward from the anterior tip of the large rotor to below the small rotor. Thirteen cases (28.3%) of coronal fractures were found on preoperative X-ray films, and 35 cases (76.1%) were found by CT three-dimensional reconstruction, showing significant difference ( χ 2=21.083, P=0.000). In AO/OTA 31-A1 type patients, the proportion of coronal fractures found by X-ray film and CT three-dimensional reconstruction was 18.2% (2/11) and 54.5% (6/11), respectively, and that in AO/OTA 31-A2 type patients was 31.4% (11/35) and 82.9% (29/35), respectively, showing significant differences ( χ 2=3.143, P=0.000; χ 2=20.902, P=0.000). Among the 35 patients with coronal fractures, 6 cases (17.1%) of AO/OTA 31-A1 type, 29 cases (82.9%) of AO/OTA 31-A2 type. The operation time of the patient was 80-112 minutes, with an average of 95 minutes; the intraoperative blood loss was 180-450 mL, with an average of 360 mL. There was no complication such as infection, falling pneumonia, and deep vein thrombosis of the lower extremities. At 3 days after operation, the internal fixators were all in the proper position. The TAD was 0.9-1.8 cm, with an average of 1.4 cm. All patients were followed up 14-18 months, with an average of 16 months. All the fractures healed osseously, and there was no complication such as nonunion and loosening of internal fixation. CONCLUSION: CT three-dimensional reconstruction can better identify coronal femoral intertrochanteric fractures than X-ray films, and accurately recognize and analyze the incidence and morphological characteristics of coronal fractures, which can help formulate more effective surgical strategies to promote patient recovery.

Rabaptin-5-independent membrane targeting and Rab5 activation by Rabex-5 in the cell.

Rabex-5 is a guanine nucleotide exchange factor (GEF) for Rab5. Here, we report the identification of a novel functional domain of Rabex-5 that is essential for its membrane targeting and Rab5 GEF activity in vivo. The data show that full-length Rabex-5 efficiently activates Rab5 in the cell. However, the GEF domain itself (residues 135-399) is inactive in this respect, despite its activity in vitro. Generation and characterization of a series of Rabex-5 constructs reveal that the GEF domain is unable to target to early endosomes and that a sequence N-terminal to the GEF domain can restore its early endosomal targeting and its ability to activate Rab5 in the cell. This region (residues 81-135) is termed membrane-binding motif, which together with the downstream helical bundle domain (residues 135-230) forms an early endosomal targeting (EET) domain necessary and sufficient for association with early endosomes. Furthermore, several active Rabex-5 constructs do not contain the Rabaptin-5-binding domain in the C-terminal region. Thus, Rabex-5 can target to early endosomes via the EET domain and activate Rab5 in a Rabaptin-5-independent manner in vivo. We discuss a model to reconcile these in vivo data with previous in vitro results on Rabex-5 function and its interaction with Rabaptin-5.

Do patients with diabetes have an increased risk of impaired fracture healing? A systematic review and meta-analysis.

BACKGROUND: The majority of the existing evidence showing an association between diabetes and impaired fracture healing comes from basic scientific research. This systematic review and meta-analysis aimed to summarize the current clinical literature that investigates fracture healing in patients with diabetes. METHODS: The outcome of interest was impaired fracture healing including non-union, delayed union and malunion. Studies that compared fracture healing outcomes between patients with and without diabetes were included in this study. Subgroup analyses regarding different fracture sites, types of fracture and classifications of diabetes were performed. RESULTS: A total of 14 studies involving 695 patients with diabetes and 4937 controls fulfilled the inclusion criteria. Diabetes was associated with an increased risk of impaired fracture healing (odds ratio (OR): 2.11, 95% confidence interval (CI) 1.33-3.37, P = 0.002). Subgroup analyses showed that diabetes was associated with a significantly higher incidence of impaired fracture healing in lower extremity fractures (OR 2.63, 95% CI 1.30-5.30, P = 0.007), short bone fractures (OR 2.64, 95% CI 1.35-5.20, P = 0.005), long bone fractures (OR 2.13, 95% CI 1.23-3.70, P = 0.007) and osteoporosis-unrelated fractures (OR 2.39, 95% CI 1.19-4.80, P = 0.01). Both insulin-dependent diabetes (OR 4.04, 95% CI 1.05-15.56, P = 0.04) and non-insulin-dependent diabetes (OR 5.83, 95% CI 1.73-19.58, P = 0.004) were associated with significantly higher risks of impaired fracture healing. CONCLUSIONS: Patients with diabetes have an increased risk of impaired fracture healing when compared to patients without diabetes. Fracture healing in the lower extremities, short bones and osteoporosis-unrelated fractures is affected more severely by diabetes.