Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 15 de 15
Filter
Add more filters










Publication year range
1.
Cell Tissue Bank ; 2023 Feb 16.
Article in English | MEDLINE | ID: mdl-36797536

ABSTRACT

The purpose of this study was to investigate whether 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) combined with n-hydroxysuccinimide (NHS) can repair tendon damage caused by peracetic acid-ethanol and gamma irradiation sterilization. The semitendinosus tendons of 15 New Zealand white rabbits were selected as experimental materials, and the tendons were sterilized in a solution containing 1% (v/w) peracetic acid and 24% (v/w) ethanol. After 15 kGy gamma irradiation sterilization, the tendons were randomly divided into three groups (n = 10). The tendons were repaired with EDCs of 0, 2.5 and 5 mM combined with 5 mM NHS for 6 h, the tendons were temporarily stored at - 80 ± °C. The arrangement and spatial structure of collagen fibers were observed by light microscopy and scanning electron microscopy, the collagen type and collagen crimp period were observed under a polarizing microscope, and the collagen fibril diameter and its distribution were measured by transmission electron microscopy, from which the collagen fibril index and mass average diameter were calculated. The resistance of collagen to enzymolysis was detected by the free hydroxyproline test, and tensile fracture and cyclic loading tests of each group of tendons were carried out, from which the elastic modulus, maximum stress, maximum strain, strain energy density and cyclic creep strain were calculated. The obtained results showed that the gap between loose collagen fibers in the 0 mM control group was wider, the parallel arrangement of tendons in the 2.5 and 5 mM groups was more uniform and regular and the fiber space decreased, the crimp period in the 5 mM group was lower than that in the 0 mM group (P < 0.05), and the concentration of hydroxyproline in the 5 mM group (711.64 ± 77.95 µg/g) was better than that in the control group (1150.57 ± 158.75 µg/g). The elastic modulus of the 5 mM group (424.73 ± 150.96 MPa) was better than that of the 0 mM group (179.09 ± 37.14 MPa). Our results show that EDC combined with NHS can repair damaged tendons after peracetic acid-ethanol and gamma radiation treatment, and 5 mM EDC has better morphological performance, anti-enzymolysis ability and biomechanical properties than 2.5 mM EDC.

2.
Clin Interv Aging ; 16: 1943-1953, 2021.
Article in English | MEDLINE | ID: mdl-34754183

ABSTRACT

PURPOSE: This study was undertaken to investigate the relationship between bisphosphonate use and intraoperative blood loss following surgery for metastatic spinal disease. METHODS: We retrospectively analyzed cancer patients who were treated by metastatic spinal tumor surgery at our institution. Recorded data included intraoperative blood loss, timing and duration of bisphosphonate use, and other important confounding factors. We showed the results of crude model, minimally adjusted model, and fully adjusted model to fully observe the effects of bisphosphonates under different adjustment strategies. The timing and duration of bisphosphonate exposure were assessed and statistical results were tested to identify a trend. RESULTS: A total of 467 patients were treated by metastatic spinal tumor surgery, with or without bisphosphonate treatments. In all adjustment strategies, intraoperative blood loss was lower in patients using bisphosphonates than in patients without bisphosphonate treatments. In the fully adjusted model, the effect size, confidence interval, and p value were -246.4, -447.0 to -45.8, and 0.017, respectively. In terms of duration, all three models showed the same duration-response relationship: a longer duration of bisphosphonate use accurately predicted a smaller amount of blood loss (p for trend <0.001). We observed an interaction between operative time and bisphosphonate use, the effect size in the bottom tertile group was significantly smaller than that in the other two groups. CONCLUSION: We found that the preoperative use of bisphosphonates could reduce the amount of intraoperative blood loss during metastatic spinal tumor surgery, especially for surgery with longer operative time.


Subject(s)
Neoplasms , Spinal Diseases , Blood Loss, Surgical/prevention & control , Diphosphonates/therapeutic use , Humans , Retrospective Studies
3.
Front Oncol ; 11: 629823, 2021.
Article in English | MEDLINE | ID: mdl-34249679

ABSTRACT

INTRODUCTION: Venous thromboembolism can be divided into deep vein thrombosis and pulmonary embolism. These diseases are a major factor affecting the clinical prognosis of patients and can lead to the death of these patients. Unfortunately, the literature on the risk factors of venous thromboembolism after surgery for spine metastatic bone lesions are rare, and no predictive model has been established. METHODS: We retrospectively analyzed 411 cancer patients who underwent metastatic spinal tumor surgery at our institution between 2009 and 2019. The outcome variable of the current study is venous thromboembolism that occurred within 90 days of surgery. In order to identify the risk factors for venous thromboembolism, a univariate logistic regression analysis was performed first, and then variables significant at the P value less than 0.2 were included in a multivariate logistic regression analysis. Finally, a nomogram model was established using the independent risk factors. RESULTS: In the multivariate logistic regression model, four independent risk factors for venous thromboembolism were further screened out, including preoperative Frankel score (OR=2.68, 95% CI 1.78-4.04, P=0.001), blood transfusion (OR=3.11, 95% CI 1.61-6.02, P=0.041), Charlson comorbidity index (OR=2.01, 95% CI 1.27-3.17, P=0.013; OR=2.29, 95% CI 1.25-4.20, P=0.017), and operative time (OR=1.36, 95% CI 1.14-1.63, P=0.001). On the basis of the four independent influencing factors screened out by multivariate logistic regression model, a nomogram prediction model was established. Both training sample and validation sample showed that the predicted probability of the nomogram had a strong correlation with the actual situation. CONCLUSION: The prediction model for postoperative VTE developed by our team provides clinicians with a simple method that can be used to calculate the VTE risk of patients at the bedside, and can help clinicians make evidence-based judgments on when to use intervention measures. In clinical practice, the simplicity of this predictive model has great practical value.

4.
Technol Cancer Res Treat ; 19: 1533033820945798, 2020.
Article in English | MEDLINE | ID: mdl-32757820

ABSTRACT

Spinal metastases are a common manifestation of malignant tumors that can cause severe pain, spinal cord compression, pathological fractures, and hypercalcemia, and these clinical manifestations will ultimately reduce the health-related quality of life and even shorten life expectancy in patient with cancer. Effective management of spinal bone metastases requires multidisciplinary collaboration, including radiologists, surgeons, radiation oncologists, medical oncologists, and pain specialists. In the past few decades, conventional radiotherapy has been the most common form of radiotherapy, which can achieve favorable local control and pain relief; however, it lacks precise methods of delivering radiation and thus cannot provide sufficient tumoricidal dose. The advent of stereotactic radiosurgery has changed this situation by using highly focused radiation beams guided by 3-dimensional imaging to deliver a high biologic equivalent dose to the target region, and the spinal cord can be identified and excluded from the target volume to reduce the risk of radiation-induced myelopathy. Separation surgery can provide a 2- to 3-mm safe separation of tumor and spinal cord to avoid radiation-induced damage to the spinal cord. Targets for separation surgery include decompression of metastatic epidural spinal cord compression and spinal stabilization without partial or en bloc tumor resection. Combined with conventional radiotherapy, stereotactic radiosurgery can provide better local tumor control and pain relief. Several scoring systems have been developed to estimate the life expectancy of patients with spinal metastases treated with radiotherapy. Thorough understanding of radiotherapy-related knowledge including the dose-fractionation schedule, separation surgery, efficacy and safety, scoring systems, and feasibility of combination with other treatment methods is critical to providing optimal patient care.


Subject(s)
Radiosurgery , Radiotherapy , Spinal Neoplasms/radiotherapy , Spinal Neoplasms/secondary , Combined Modality Therapy , Disease Management , Dose Fractionation, Radiation , Humans , Radiosurgery/adverse effects , Radiosurgery/methods , Radiotherapy/adverse effects , Radiotherapy/methods , Radiotherapy Dosage , Treatment Outcome
5.
J Arthroplasty ; 35(10): 2944-2951, 2020 10.
Article in English | MEDLINE | ID: mdl-32482479

ABSTRACT

BACKGROUND: Megaprosthetic replacement is one of the main methods for reconstructing mega bone defects after tumor resection. However, the incidences of complication associated with tumor prostheses were 5-10 times higher than that of conventional total knee arthroplasty. The objective of this study is to establish and validate a nomogram model which can assist doctors and patients in predicting the prosthetic survival rates. METHODS: Data on cancer patients treated with tumor prosthesis replacements at our institution from November 2001 to November 2017 were collected. The potential risk factors which were well-studied and shown to be associated with megaprosthetic failure were analyzed. A nomogram model was established using independent risk factors screened out by multivariate regression analysis. The concordance index and calibration curve were selected for internal validation of the predictive accuracy of nomogram. RESULTS: The 3-, 5-, 10-, and 15-year prosthetic survival rates were 92.8%, 88.6%, 74.1%, and 48.3%, respectively. The prosthetic motion mode, body mass index, type of reconstruction, type of prosthesis, and length of bone resection were independent risk factors for tumor prosthetic failure. A nomogram model was established using these significant predictors, with a concordance index of 0.77 and a favorable consistency between predicted and actual prosthetic failure rate according to the internal validation, indicating that the nomogram model had acceptable predictive accuracy. CONCLUSION: The prediction model identifies high-risk patients for whom attached preventive measures are required. Future studies regarding reduction in incidence of prosthetic failure should attach importance to these high-risk patients.


Subject(s)
Arthroplasty, Replacement, Knee , Nomograms , Arthroplasty, Replacement, Knee/adverse effects , Humans , Incidence , Prognosis , Retrospective Studies , Risk Factors
6.
Int Orthop ; 44(7): 1427-1433, 2020 07.
Article in English | MEDLINE | ID: mdl-32435955

ABSTRACT

PURPOSE: Aseptic loosening is a common prosthetic failure mode. The purpose of this study was to identify dose-response relationship between length of femoral stem and aseptic loosening. METHODS: We collected data of patients who underwent distal femoral prosthetic replacements at our institution from 2001 to 2017. Cox regression and two-piecewise regression model were used to analyze the associations between stem length and aseptic loosening. RESULTS: Significant association of length of femoral stem with aseptic loosening was observed in multivariate model and a non-linear relationship could be found from the smoothed curve. In two-piecewise model, an inflection point was calculated to be 143 mm. On the left of the inflection point, every 1 mm increase in the length of stem indicated that the risk of aseptic loosening could be reduced by 6%. CONCLUSION: There was a significant non-linear relationship between the length of femoral stem and aseptic loosening, and the inflection point was 143 mm.


Subject(s)
Arthroplasty, Replacement, Hip , Hip Prosthesis , Neoplasms , Arthroplasty, Replacement, Hip/adverse effects , Femur/diagnostic imaging , Femur/surgery , Hip Prosthesis/adverse effects , Humans , Prosthesis Design , Prosthesis Failure , Reoperation
7.
Orthop Surg ; 12(2): 617-630, 2020 Apr.
Article in English | MEDLINE | ID: mdl-32189444

ABSTRACT

OBJECTIVE: To assess the defatting efficacy of high pressure washing and gradient alcohol and biomechanical properties of defatted bone. METHODS: Fresh cancellous bone was obtained from the femoral condyle and divided into six groups according to different defatting treatments, which were: high pressure washing for 10 s (10S group), 20 s (20S group), and 30 s (30S group), gradient alcohol immersion (Alcohol group), acetone immersion (Acetone group), and non-defatted (Fresh group). The appearance of six groups was observed, and the appearance of defatted bone and fresh bone was compared. The residual lipid content and infrared spectrum were used to compare the efficacy of defatting, the DNA content was used to compare the cell content after defatting, and the maximum stress and elastic modulus were used to compare the effects of defatting treatment on biomechanical properties. RESULTS: The fresh bone was yellow and the pores contained a lot of fat. The defatted bone was white and the porous network was clear. There was no difference in residual lipid content among the three groups with high pressure washing (1.45% ± 0.16%, 1.40% ± 0.13%, and 1.46% ± 0.11%, respectively) (P = 0.828). There was no difference in residual lipid content among the 10S, alcohol, and acetone groups (1.45% ± 0.16%, 1.28% ± 0.07%, and 1.13% ± 0.22%, respectively) (P = 0.125). Infrared spectra showed that the fat content of the five defatting groups was significantly lower than that of the fresh group. There was no difference in residual lipid content among the three groups with high pressure washing (4.53 ± 0.23 ug/mL, 4.61 ± 0.18 ug/mL, and 4.66 ± 0.25 ug/mL, respectively) (P = 0.645). There was no difference in residual lipid content among the 10S, alcohol, and acetone groups (4.53 ± 0.23 ug/mL, 4.29 ± 0.24 ug/mL, and 4.27 ± 0.29 ug/mL, respectively) (P = 0.247). The maximum stress of the bone decreased significantly with the increase of the washing time (9.95 ± 0.31 Mpa, 9.07 ± 0.45 Mpa, and 8.17 ± 0.35 Mpa, respectively) (P = 0.003). The elastic modulus of the bone decreased significantly with the increase of the washing time (116.40 ± 3.54 Mpa, 106.10 ± 5.29 Mpa, and 95.63 ± 4.08 Mpa, respectively) (P = 0.003). There was no statistical difference in the maximum stress between the fresh group, the 10S group, the alcohol group, and the acetone group (10.09 ± 0.67 Mpa, 9.95 ± 0.31 Mpa, 10.11 ± 0.07 Mpa, and 10.09 ± 0.39 Mpa, respectively) (P = 0.963). There was no statistical difference in the maximum stress between the fresh group, the 10S group, the alcohol group and the acetone group (119.93 ± 4.94 Mpa, 116.40 ± 3.54 Mpa, 118.27 ± 0.85 Mpa, 118.10 ± 4.52 Mpa, respectively) (P = 0.737). CONCLUSION: The defatting efficiency was satisfactory at a time of 10 s under high pressure washing. In terms of defatting efficiency and its effect on biomechanical properties of bone, high pressure washing and gradient alcohol were similar to conventional acetone solvent extraction defatting.


Subject(s)
Allografts/physiology , Cancellous Bone/physiology , Lipids , Acetone/pharmacology , Biomechanical Phenomena , Ethanol/pharmacology , Humans , Pressure
8.
Cancer Lett ; 475: 136-142, 2020 04 10.
Article in English | MEDLINE | ID: mdl-32032679

ABSTRACT

Bone metastasis is a common complication of cancer, and bone is the third most common metastatic site following the lung and liver. Among the various bones, spine is the most common site of metastatic tumors. The treatment goals of patients with spinal metastases are mostly palliative, with the aim of reducing pain and improving quality of life. The treatment of spinal metastases has made significant progress over the past few decades. Each new technology has tried to solve the shortcomings of its predecessors. Currently, there are no mature algorithms or specific techniques that have proven to be the best for spinal metastases, and the treatment method often relies on operator and institutional preferences or biases in some cases. Percutaneous vertebral augmentation has unique value in the management of spinal metastases, understanding its indications, surgical techniques, uses, advantages and complications is critical to providing optimal patient care. We believe that the application of percutaneous vertebral augmentation alone or combined with other techniques can achieve optimal pain relief and functional improvement in the patients with spinal metastases.


Subject(s)
Quality of Life , Spinal Neoplasms/secondary , Spinal Neoplasms/therapy , Vertebroplasty/methods , Disease Management , Humans
9.
Orthop Traumatol Surg Res ; 106(3): 421-427, 2020 May.
Article in English | MEDLINE | ID: mdl-31964594

ABSTRACT

BACKGROUND: Due to the particularity of patients with bone tumors, the risk of periprosthetic infection following megaprosthetic replacement is much higher than that of traditional total knee arthroplasty. Unfortunately, few studies specifically reported the risk factors for periprosthetic infection following megaprosthetic replacement. The purposes of the study were to (1) establish a nomogram model, which can provide a reference for clinicians, and patients to reduce the occurrence of periprosthetic infection (2) explore the risk factors for deep infection of megaprosthesis. HYPOTHESIS: A prediction model can be established and has favorable predictive accuracy. PATIENTS AND METHODS: One hundred and seventy-seven megaprostheses were identified. There were 61 female patients and 116 male patients with a mean age of 35 years. The following risk factors were analyzed: tumor site, sex, age, material for prosthetic stem, tumor type, smoking, diabetes, length of bone resection, operation time, chemotherapy, BMI, malignant tumor staging and hematoma formation. Finally, based on the multivariate analysis, the independent risk factors were used to develop a nomogram model. RESULTS: Univariate Cox regression analysis showed that the chemotherapy, longer operation time and hematoma formation were risk factors for periprosthetic infection. Multivariate Cox regression analysis showed that the chemotherapy, longer operation time and hematoma formation were significant risk factors for periprosthetic infection. The nomogram model was established using these significant risk factors, with a C-index of 0.766 and an acceptable consistency according to the internal validation, indicating that the prediction model had favorable predictive accuracy. DISCUSSION: This study has important implications for the future investigations of prevention of periprosthetic infection. The nomogram model identifies high-risk patients for whom attached prophylaxis measures are required. Future studies regarding reduction of incidence of periprosthetic infection should pay close attention to these high-risk patients. LEVEL OF EVIDENCE: IV, retrospective, cohort study.


Subject(s)
Bone Neoplasms , Nomograms , Adult , Bone Neoplasms/surgery , Cohort Studies , Female , Humans , Knee Joint , Male , Retrospective Studies
10.
Orthop Surg ; 11(6): 1039-1047, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31823501

ABSTRACT

OBJECTIVES: To summarize the epidemiological characteristics of patients following surgery for spinal metastases retrospectively and make a univariate analysis to identify independent variables that could affect the operation decision making. METHODS: This was a multicenter retrospective review of patients with spinal metastasis who were treated with surgery from 1 January 2007 to 31 July 2019. Basic clinical data were analyzed retrospectively by univariate analysis to identify independent variables that could affect the decision of operation modalities, including gender, age, spinal metastatic site, Frankel score, Karnofsky performance score (KPS), spinal instability neoplastic score (SINS), visual analogue scale (VAS), Tokuhashi score, urinary and fecal incontinence, spinal pathological fracture, primary tumor, extraspinal metastasis, visceral metastasis, and bone lesion (osteolytic, osteoblastic or mixed). RESULTS: A total of 580 patients including 332 males and 248 females were enrolled in the study with an average age of 58.26 years old (range, 13-86 years old). The most common spinal metastatic level was the thoracic vertebra (190 [32.76%]), followed by the lumbar vertebra (146 [25.17%]), cervical vertebra (47 [8.10%]), and sacral vertebra (35 [6.03%]). Metastases involving more than two sites of the cervical, thoracic, lumbar, and sacral vertebrae arose in 162 (27.93%) patients. For primary tumor, there were 198 (34.14%) cases of lung cancer, 41 (7.07%) cases of kidney cancer, 39 (6.72%) cases of breast cancer, 38 (6.55%) cases of gastrointestinal cancer, 35 (6.03%) cases of lymphoma and myeloma, 25 (4.31%) cases of prostate cancer, 24 (4.14%) cases of liver cancer, 23 (3.97%) cases of mesenchymal tissue sarcoma, 20 (3.45%) cases of thyroid cancer, and 84 (14.48%) cases were tumor with unknown origin. Sixty-three (10.86%) patients received minimally invasive surgery, 460 (79.31%) patients received palliative surgery, and the remaining 57 (9.83%) received tumor resection. According to the univariate analysis, the KPS score, SINS score, VAS score, Tokuhashi score, urinary and fecal incontinence, spinal pathological fracture, and bone lesion (osteolytic, osteoblastic or mixed) were independent and favorable factors affecting the surgery modalities. CONCLUSIONS: Surgical treatment for spinal metastases was mainly to relieve pain, rebuild spinal stability, improve nerve function, control local tumors, and improve the quality of life of patients. For middle-aged and elderly patients with good general conditions, severe pain, spinal pathological fracture, spine instability and without urinary and fecal incontinence, early surgical treatment should be actively carried out.


Subject(s)
Spinal Neoplasms/epidemiology , Spinal Neoplasms/secondary , Spinal Neoplasms/surgery , Adolescent , Adult , Aged , Aged, 80 and over , China/epidemiology , Female , Humans , Male , Middle Aged , Pain Measurement , Quality of Life , Retrospective Studies , Risk Factors , Surveys and Questionnaires , Young Adult
11.
Orthop Surg ; 11(6): 1048-1053, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31755205

ABSTRACT

OBJECTIVES: To describe the epidemiological characteristics of patients with spinal metastases between 2007 and 2019. METHODS: Patients with spinal metastases were identified from several clinical centers in China between January 2007 and July 2019. Demographics, primary tumor types, spinal involvement, and Clinical indicators of each patient were reviewed. RESULTS: A total of 1196 patients were included in this study, 717 males (59.95%) and 479 females (40.05%), with a male to female ratio of 1.50:1. Most patients (63.71%) were in the ages range of 50 to 69 years. The mean age was 58.6 ± 11.6 (range 13-89) years and the median age was 59.0 years. The average age of females was younger than that of males, and the difference was statistically significant. The proportion of male patients over 60 years old was higher than that of females, and the difference was statistically significant. The most common primary tumor was lung cancer (n = 437, 36.54%), followed by unknown origin (n = 194, 16.22%), kidney cancer (n = 78, 6.52%), breast cancer (n = 76, 6.35%), and liver/biliary cancer (n = 75, 6.27%). The most common primary tumor was lung cancer in both males and females, followed by unknown origin in males and breast cancer in females. There were 730 patients (61.04%) in the subgroup of the number<3; the highest level was lumbar vertebrae, with 250 patients (34.25%). The remaining 466 patients (38.96%) were included in the subgroup of the number ≥ 3; the highest level was tumor metastasis of multiple-level of spine, with 334 patients (71.67%). Among the 1196 patients, spinal cord injury occurred in 54.01% of patients, 76.34% of patients developed moderate and above pain, 55.69% of patients had metastatic spinal cord compression, and only 26.67% of patients had a clear history of primary tumors. CONCLUSION: This study provided a relatively detailed description of epidemiological characteristics in spinal metastases in China, which could assist orthopaedic surgeons to understand the clinical characteristics of spinal metastases, and is of great significance in guiding clinical diagnoses and scientific research.


Subject(s)
Spinal Neoplasms/epidemiology , Spinal Neoplasms/secondary , Adolescent , Adult , Aged , Aged, 80 and over , China/epidemiology , Female , Humans , Male , Middle Aged , Pain Measurement , Retrospective Studies , Surveys and Questionnaires , Young Adult
12.
J Orthop Surg Res ; 14(1): 352, 2019 Nov 09.
Article in English | MEDLINE | ID: mdl-31706336

ABSTRACT

BACKGROUND: Aseptic loosening has become the main cause of prosthetic failure in medium- to long-term follow-up. The objective of this study was to establish and validate a nomogram model for aseptic loosening after tumor prosthetic replacement around knee. METHODS: We collected data on patients who underwent tumor prosthetic replacements. The following risk factors were analyzed: tumor site, stem length, resection length, prosthetic motion mode, sex, age, extra-cortical grafting, custom or modular, stem diameter, stem material, tumor type, activity intensity, and BMI. We used univariate and multivariate Cox regression for analysis. Finally, the significant risk factors were used to establish the nomogram model. RESULTS: The stem length, resection length, tumor site, and prosthetic motion mode showed a tendency to be related to aseptic loosening, according to the univariate analysis. Multivariate analysis showed that the tumor site, stem length, and prosthetic motion mode were independent risk factors. The internal validation indicated that the nomogram model had acceptable predictive accuracy. CONCLUSIONS: A nomogram model was developed for predicting the prosthetic survival rate without aseptic loosening. Patients with distal femoral tumors and those who are applied with fixed hinge and short-stem prostheses are more likely to be exposed to aseptic loosening.


Subject(s)
Bone Neoplasms/surgery , Knee Prosthesis/trends , Nomograms , Osteonecrosis/surgery , Osteosarcoma/surgery , Prosthesis Failure/trends , Adolescent , Adult , Aged , Bone Neoplasms/diagnostic imaging , Female , Follow-Up Studies , Humans , Knee Prosthesis/adverse effects , Male , Middle Aged , Osteonecrosis/diagnostic imaging , Osteosarcoma/diagnostic imaging , Prosthesis Failure/adverse effects , Retrospective Studies , Young Adult
13.
Cell Discov ; 2: 16003, 2016.
Article in English | MEDLINE | ID: mdl-27462450

ABSTRACT

The biogenesis of photosystem I (PSI), cytochrome b 6 f (Cytb 6 f) and NADH dehydrogenase (NDH) complexes relies on the spatially and temporally coordinated expression and translation of both nuclear and chloroplast genes. Here we report the identification of photosystem biogenesis regulator 1 (PBR1), a nuclear-encoded chloroplast RNA-binding protein that regulates the concerted biogenesis of NDH, PSI and Cytb 6 f complexes. We identified Ycf1, one of the two largest chloroplast genome-encoded open reading frames as the direct downstream target protein of PBR1. Biochemical and molecular analyses reveal that PBR1 regulates Ycf1 translation by directly binding to its mRNA. Surprisingly, we further demonstrate that relocation of the chloroplast gene Ycf1 fused with a plastid-transit sequence to the nucleus bypasses the requirement of PBR1 for Ycf1 translation, which sufficiently complements the defects in biogenesis of NDH, PSI and Cytb 6 f complexes in PBR1-deficient plants. Remarkably, the nuclear-encoded PBR1 tightly controls the expression of the chloroplast gene Ycf1 at the translational level, which is sufficient to sustain the coordinated biogenesis of NDH, PSI and Cytb 6 f complexes as a whole. Our findings provide deep insights into better understanding of how a predominant nuclear-encoded factor can act as a migratory mediator and undergoes selective translational regulation of the target plastid gene in controlling biogenesis of photosynthetic complexes.

14.
PLoS Genet ; 8(5): e1002669, 2012.
Article in English | MEDLINE | ID: mdl-22570631

ABSTRACT

Heat stress commonly leads to inhibition of photosynthesis in higher plants. The transcriptional induction of heat stress-responsive genes represents the first line of inducible defense against imbalances in cellular homeostasis. Although heat stress transcription factor HsfA2 and its downstream target genes are well studied, the regulatory mechanisms by which HsfA2 is activated in response to heat stress remain elusive. Here, we show that chloroplast ribosomal protein S1 (RPS1) is a heat-responsive protein and functions in protein biosynthesis in chloroplast. Knockdown of RPS1 expression in the rps1 mutant nearly eliminates the heat stress-activated expression of HsfA2 and its target genes, leading to a considerable loss of heat tolerance. We further confirm the relationship existed between the downregulation of RPS1 expression and the loss of heat tolerance by generating RNA interference-transgenic lines of RPS1. Consistent with the notion that the inhibited activation of HsfA2 in response to heat stress in the rps1 mutant causes heat-susceptibility, we further demonstrate that overexpression of HsfA2 with a viral promoter leads to constitutive expressions of its target genes in the rps1 mutant, which is sufficient to reestablish lost heat tolerance and recovers heat-susceptible thylakoid stability to wild-type levels. Our findings reveal a heat-responsive retrograde pathway in which chloroplast translation capacity is a critical factor in heat-responsive activation of HsfA2 and its target genes required for cellular homeostasis under heat stress. Thus, RPS1 is an essential yet previously unknown determinant involved in retrograde activation of heat stress responses in higher plants.


Subject(s)
Arabidopsis , Chloroplast Proteins , DNA-Binding Proteins/genetics , Heat-Shock Proteins/genetics , Heat-Shock Response , Plant Proteins/genetics , Ribosomal Proteins/genetics , Transcription Factors/genetics , Arabidopsis/genetics , Arabidopsis/physiology , Arabidopsis Proteins , Chloroplast Proteins/genetics , Chloroplast Proteins/metabolism , Chloroplasts/genetics , Chloroplasts/metabolism , Chloroplasts/physiology , DNA-Binding Proteins/metabolism , Gene Expression Regulation, Plant , Heat Shock Transcription Factors , Heat-Shock Proteins/metabolism , Heat-Shock Response/genetics , Mutation , Plant Proteins/metabolism , Plants, Genetically Modified , RNA Interference , Ribosomal Proteins/metabolism , Transcription Factors/metabolism
15.
Mol Plant ; 5(5): 1082-99, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22402261

ABSTRACT

Sedoheptulose-1,7-bisphosphatase (SBPase) is a Calvin cycle enzyme and functions in photosynthetic carbon fixation. We found that SBPase was rapidly carbonylated in response to methyl viologen (MV) treatments in detached leaves of Arabidopsis plants. In vitro activity analysis of the purified recombinant SBPase showed that SBPase was carbonylated by hydroxyl radicals, which led to enzyme inactivation in an H(2)O(2) dose-dependent manner. To determine the conformity with carbonylation-caused loss in enzymatic activity in response to stresses, we isolated a loss-of-function mutant sbp, which is deficient in SBPase-dependent carbon assimilation and starch biosynthesis. sbp mutant exhibited a severe growth retardation phenotype, especially for the developmental defects in leaves and flowers where SBPASE is highly expressed. The mutation of SBPASE caused growth retardation mainly through inhibition of cell division and expansion, which can be partially rescued by exogenous application of sucrose. Our findings demonstrate that ROS-induced oxidative damage to SBPase affects growth, development, and chloroplast biogenesis in Arabidopsis through inhibiting carbon assimilation efficiency. The data presented here provide a case study that such inactivation of SBPase caused by carbonyl modification may be a kind of adaptation for plants to restrict the operation of the reductive pentose phosphate pathway under stress conditions.


Subject(s)
Arabidopsis Proteins/metabolism , Arabidopsis/enzymology , Arabidopsis/growth & development , Carbon/metabolism , Oxidative Stress , Phosphoric Monoester Hydrolases/metabolism , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis Proteins/genetics , Down-Regulation , Phosphoric Monoester Hydrolases/genetics , Protein Carbonylation
SELECTION OF CITATIONS
SEARCH DETAIL
...