Association between lumbar muscle size and bone mineral density in nonfractured postmenopausal women with and without osteoporosis

OBJECTIVE

Estrogen deficiency in postmenopausal women is associated with bone loss and a decline in muscle mass. However, the associations between lumbar muscle size and bone mineral density (BMD) in postmenopausal women with and without osteoporosis remain unclear. The aim of this study was to investigate the associations between lumbar muscle size and BMD in nonfractured postmenopausal women with osteoporosis and those with osteopenia.

METHODS

A total of 89 postmenopausal women with osteopenia (n = 53) and osteoporosis (n = 36) were retrospectively enrolled in this study from 2014 to 2022. All participants underwent lumbar magnetic resonance imaging and dual-energy absorptiometry within a month. The lean lumbar muscle sizes at different lumbar levels were quantitatively evaluated on axial T1-weighted images. The associations between lumbar muscle size and BMD were analyzed using Pearson's correlation analysis.

RESULTS

The osteoporosis group had significantly smaller lean psoas muscle sizes than the osteopenia group. Based on the correlation analysis, the erector spinae and multifidus muscle sizes were significantly associated with lumbar and femoral neck BMDs in the osteoporosis group. However, no significant association was found between lean psoas muscle size and BMDs in the osteopenia group. Thus, the associations between lumbar muscle decline and bone loss differed between postmenopausal women with osteoporosis and those with osteopenia.

CONCLUSIONS

The study findings suggest differences in the associations between BMD and lumbar muscle size between postmenopausal women with osteoporosis and those with osteopenia.

CXCL1 enhances COX-II expression in rheumatoid arthritis synovial fibroblasts by CXCR2, PLC, PKC, and NF-κB signal pathway

Rheumatoid arthritis (RA) is the most common autoimmune disease, affecting the joints of the hands and feet. Several chemokines and their receptors are crucial in RA pathogenesis through immune cell recruitment. C-X-C Motif Chemokine Ligand 1 (CXCL1), a chemokine for the recruitment of various immune cells, can be upregulated in patients with RA. However, the discussion on the role of CXCL1 in RA pathogenesis is insufficient. Here, we found that CXCL1 promoted cyclooxygenase-2 (COX-II) expression in a dose- and time-dependent manner in rheumatoid arthritis synovial fibroblasts (RASFs). CXCL1 overexpression in RASFs led to a significant increase in COX-II expression, while the transfection of RASFs with the shRNA plasmid resulted in a noticeable decrease in COX-II expression. Next, we delineated the molecular mechanism underlying CXCL1-promoted COX-II expression and noted that CXC chemokine receptor 2 (CXCR2), phospholipase C (PLC), and protein kinase C (PKC) signal transduction were responsible for COX-II expression after CXCL1 incubation for RASFs. Finally, we confirmed the transcriptional activation of nuclear factor κB (NF-κB) in RASFs after incubation with CXCL1. In conclusion, the current study provided a novel insight into the role of CXCL1 in RA pathogenesis.

Hyperthermia increases HSP production in human PDMCs by stimulating ROS formation, p38 MAPK and Akt signaling, and increasing HSF1 activity

Background

Human placenta-derived multipotent cells (hPDMCs) are isolated from a source uncomplicated by ethical issues and are ideal for therapeutic applications because of their capacity for multilineage differentiation and proven immunosuppressive properties. It is known that heat shock preconditioning induces the upregulation of heat shock proteins (HSPs), which enhance survival and engraftment of embryonic stem cells (ESCs) during transplantation in live animal models, although whether heat shock preconditioning has the same effects in hPDMCs is unclear.

Methods

The hPDMCs were isolated from placenta of healthy donors. The cells were treated with heat shock (43 °C, 15 min), followed by evaluation of cell viability. Furthermore, the HSPs expression was assessed by Western blot, qPCR. The reactive oxygen species (ROS) production and signal pathway activation were determined by flow cytometry and Western blot, respectively. The regulatory pathways involved in HSPs expression were examined by pretreatment with chemical inhibitors, and siRNAs of MAPK, Akt, and heat shock factor 1 (HSF1), followed by determination of HSPs expression.

Results

This study demonstrates that heat shock treatment induced ROS generation and HPSs expression in hPDMCs. Heat shock stimulation also increased p38 MAPK and Akt phosphorylation. These effects were reduced by inhibitors of ROS, p38 MAPK and Akt. Moreover, we found that heat shock treatment enhanced nuclear translocation of the HSF1 in hPDMCs, representing activation of HSF1. Pretreatment of hPDMCs with ROS scavengers, SB203580 and Akt inhibitors also reduced the translocation of HSF1 induced by heat shock.

Conclusions

Our data indicate that heat shock acts via ROS to activate p38 MAPK and Akt signaling, which subsequently activates HSF1, leading to HSP activation and contributing to the protective role of hPDMCs.

International Validation of the SORG Machine-learning Algorithm for Predicting the Survival of Patients with Extremity Metastases Undergoing Surgical Treatment

BACKGROUND

The Skeletal Oncology Research Group machine-learning algorithms (SORG-MLAs) estimate 90-day and 1-year survival in patients with long-bone metastases undergoing surgical treatment and have demonstrated good discriminatory ability on internal validation. However, the performance of a prediction model could potentially vary by race or region, and the SORG-MLA must be externally validated in an Asian cohort. Furthermore, the authors of the original developmental study did not consider the Eastern Cooperative Oncology Group (ECOG) performance status, a survival prognosticator repeatedly validated in other studies, in their algorithms because of missing data.

QUESTIONS/PURPOSES

(1) Is the SORG-MLA generalizable to Taiwanese patients for predicting 90-day and 1-year mortality? (2) Is the ECOG score an independent factor associated with 90-day and 1-year mortality while controlling for SORG-MLA predictions?

METHODS

All 356 patients who underwent surgery for long-bone metastases between 2014 and 2019 at one tertiary care center in Taiwan were included. Ninety-eight percent (349 of 356) of patients were of Han Chinese descent. The median (range) patient age was 61 years (25 to 95), 52% (184 of 356) were women, and the median BMI was 23 kg/m2 (13 to 39 kg/m2). The most common primary tumors were lung cancer (33% [116 of 356]) and breast cancer (16% [58 of 356]). Fifty-five percent (195 of 356) of patients presented with a complete pathologic fracture. Intramedullary nailing was the most commonly performed type of surgery (59% [210 of 356]), followed by plate screw fixation (23% [81 of 356]) and endoprosthetic reconstruction (18% [65 of 356]). Six patients were lost to follow-up within 90 days; 30 were lost to follow-up within 1 year. Eighty-five percent (301 of 356) of patients were followed until death or for at least 2 years. Survival was 82% (287 of 350) at 90 days and 49% (159 of 326) at 1 year. The model's performance metrics included discrimination (concordance index [c-index]), calibration (intercept and slope), and Brier score. In general, a c-index of 0.5 indicates random guess and a c-index of 0.8 denotes excellent discrimination. Calibration refers to the agreement between the predicted outcomes and the actual outcomes, with a perfect calibration having an intercept of 0 and a slope of 1. The Brier score of a prediction model must be compared with and ideally should be smaller than the score of the null model. A decision curve analysis was then performed for the 90-day and 1-year prediction models to evaluate their net benefit across a range of different threshold probabilities. A multivariate logistic regression analysis was used to evaluate whether the ECOG score was an independent prognosticator while controlling for the SORG-MLA's predictions. We did not perform retraining/recalibration because we were not trying to update the SORG-MLA algorithm in this study.

RESULTS

The SORG-MLA had good discriminatory ability at both timepoints, with a c-index of 0.80 (95% confidence interval 0.74 to 0.86) for 90-day survival prediction and a c-index of 0.84 (95% CI 0.80 to 0.89) for 1-year survival prediction. However, the calibration analysis showed that the SORG-MLAs tended to underestimate Taiwanese patients' survival (90-day survival prediction: calibration intercept 0.78 [95% CI 0.46 to 1.10], calibration slope 0.74 [95% CI 0.53 to 0.96]; 1-year survival prediction: calibration intercept 0.75 [95% CI 0.49 to 1.00], calibration slope 1.22 [95% CI 0.95 to 1.49]). The Brier score of the 90-day and 1-year SORG-MLA prediction models was lower than their respective null model (0.12 versus 0.16 for 90-day prediction; 0.16 versus 0.25 for 1-year prediction), indicating good overall performance of SORG-MLAs at these two timepoints. Decision curve analysis showed SORG-MLAs provided net benefits when threshold probabilities ranged from 0.40 to 0.95 for 90-day survival prediction and from 0.15 to 1.0 for 1-year prediction. The ECOG score was an independent factor associated with 90-day mortality (odds ratio 1.94 [95% CI 1.01 to 3.73]) but not 1-year mortality (OR 1.07 [95% CI 0.53 to 2.17]) after controlling for SORG-MLA predictions for 90-day and 1-year survival, respectively.

CONCLUSION

SORG-MLAs retained good discriminatory ability in Taiwanese patients with long-bone metastases, although their actual survival time was slightly underestimated. More international validation and incremental value studies that address factors such as the ECOG score are warranted to refine the algorithms, which can be freely accessed online at https://sorg-apps.shinyapps.io/extremitymetssurvival/.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Thrombospondin 2 Promotes IL-6 Production in Osteoarthritis Synovial Fibroblasts via the PI3K/AKT/NF-κB Pathway

Background

It is known that osteoarthritis (OA) pathogenesis involves inflammation that drives pathologic changes and that the matricellular protein, thrombospondin-2 (TSP2), is involved in angiogenesis, carcinogenesis, and inflammation. However, how TSP2 contributes to OA inflammatory processes is unclear.

Objective

The aim of current study was to elucidate whether TSP2 could promote interleukin-6 (IL-6), a pro-inflammatory cytokine, expression in osteoarthritis synovial fibroblasts (OASFs).

Methods

The synovial fibroblasts isolated from osteoarthritis and healthy donors were incubated with recombinant TSP2 to evaluate its effect in OA pathogenesis. The SFs were incubated with recombinant TSP2, followed by determining the IL-6 expression by qPCR and Western blot. After SFs were incubated with TSP2 for different time interval, the Western blot was performed to investigate the activation of signal pathway. The different strategies including neutralizing antibodies, siRNAs, and chemical inhibitors were used to discover the signal transduction in response to TSP2 incubation in OASFs. To evaluate the therapeutic potential of TSP2 in osteoarthritis, the anterior cruciate ligament transection (ACLT) in SD rats was performed in the presence or absence of TSP neutralizing antibody treatment.

Results

Our investigations have revealed that TSP2 promoted IL-6 expression in OASFs in a dose-dependent manner, especially in 30 and 100 ng/mL concentration (p < 0.05). Using different strategies including neutralizing antibodies, siRNAs, and chemical inhibitors, all of which attenuated signal pathway components in OASFs, we found evidence for the involvement of integrin α_vβ₃, PI3K, Akt, and NF-κB in TSP2-mediated upregulation of IL-6 (p < 0.05). Finally, in the result of rat ACLT surgical model, we found that TSP2 neutralizing antibody had protective effects in cartilage destruction during OA progression.

Conclusion

Thrombospondin-2 palys an important role in osteoarthritis pathogenesis and provides an opportunity to deal with osteoarthritis.

Monocyte Chemoattractant Protein-1 promotes cancer cell migration via c-Raf/MAPK/AP-1 pathway and MMP-9 production in osteosarcoma

Background

Osteosarcoma is generally reported among younger individuals and has a very poor prognosis, particularly for the development of metastasis. However, more effective metastatic biomarkers and therapeutic methods are absent. Monocyte chemoattractant protein-1 (MCP-1) is involved in cancer progression and inflammatory recruitment. Although previous studies have reported higher serum MCP-1 levels in patients with osteosarcoma, the role of MCP-1 in osteosarcoma progression remains to be addressed.

Methods

The osteosarcoma cell migratory ability was assessed by transwell migration assay. The MCP-1 and MMP-9 expression levels were analyzed by Western blot and qPCR. The signal activation was conducted by Western blot. The in vivo mouse experiment and tumor tissue array were performed to confirm our findings in vitro.

Results

The present study demonstrates that MCP-1 regulates cell mobility through matrix metalloproteinase (MMP)-9 expression in osteosarcoma cells. Moreover, MCP-1 promotes MMP-9 expression, cell migration, and cell invasion by mediating CCR2, c-Raf, MAPK, and AP-1 signal transduction. Using MCP-1 knockdown stable cell lines, we found that MCP-1 knockdown reduces MMP-9 expression and cell mobility. Finally, we found high MCP-1 expression levels in osteosarcoma specimens.

Conclusions

Our results provide prognostic value of MCP-1 in osteosarcoma by promoting MMP-9 expression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01756-y.

Thrombospondin-2 stimulates MMP-9 production and promotes osteosarcoma metastasis via the PLC, PKC, c-Src and NF-κB activation

Osteosarcoma is an extremely common primary bone malignancy that is highly metastatic, with most deaths resulting from pulmonary metastases. The extracellular matrix protein thrombospondin‐2 (TSP‐2) is key to many biological processes, such as inflammation, wound repair and tissue remodelling. However, it is unclear as to what biological role TSP‐2 plays in human metastatic osteosarcoma. The immunochemistry analysis from osteosarcoma specimens identified marked up‐regulation of TSP‐2 in late‐stage osteosarcoma. Furthermore, we found that TSP‐2 increased the levels of matrix metallopeptidase 9 (MMP‐9) expression and thereby increased the migratory potential of human osteosarcoma cells. Osteosarcoma cells pre‐treated with an MMP‐9 monoclonal antibody (mAb), an MMP‐9 inhibitor, or transfected with MMP‐9 small interfering RNA (siRNA) reduced the capacity of TSP‐2 to potentiate cell migration. TSP‐2 treatment activated the PLCβ, PKCα, c‐Src and nuclear kappa factor B (NF‐κB) signalling pathways, while the specific siRNA, inhibitors and mutants of these cascades reduced TSP‐2‐induced stimulation of migration activity. Knockdown of TSP‐2 expression markedly reduced cell metastasis in cellular and animal experiments. It appears that an interaction between TSP‐2 and integrin αvβ3 activates the PLCβ, PKCα and c‐Src signalling pathways and subsequently activates NF‐κB signalling, increasing MMP‐9 expression and stimulating migratory activity amongst human osteosarcoma cells.

Using C-doped TiO2 Nanoparticles as a Novel Sonosensitizer for Cancer Treatment

Sonodynamic therapy is an effective treatment for eliminating tumor cells by irradiating sonosentitizer in a patient's body with higher penetration ultrasound and inducing the free radicals. Titanium dioxide has attracted the most attention due to its properties among many nanosensitizers. Hence, in this study, carbon doped titanium dioxide, one of inorganic materials, is applied to avoid the foregoing, and furthermore, carbon doped titanium dioxide is used to generate ROS under ultrasound irradiation to eliminate tumor cells. Spherical carbon doped titanium dioxide nanoparticles are synthesized by the sol-gel process. The forming of C-Ti-O bond may also induce defects in lattice which would be beneficial for the phenomenon of sonoluminescence to improve the effectiveness of sonodynamic therapy. By dint of DCFDA, WST-1, LDH and the Live/Dead test, carbon doped titanium dioxide nanoparticles are shown to be a biocompatible material which may induce ROS radicals to suppress the proliferation of 4T1 breast cancer cells under ultrasound treatment. From in vivo study, carbon doped titanium dioxide nanoparticles activated by ultrasound may inhibit the growth of the 4T1 tumor, and it showed a significant difference between sonodynamic therapy (SDT) and the other groups on the seventh day of the treatment.

Additively manufactured biomedical Ti-Nb-Ta-Zr lattices with tunable Young's modulus: Mechanical property, biocompatibility, and proteomics analysis

Some β-Ti alloys, such as Ti-Nb-Ta-Zr (TNTZ) alloys, exhibit a low Young's modulus and excellent biocompatibility. These alloys are promising new generation biomedical implant materials. Selective laser melting (SLM) can further enable customer-specific manufacturing of β-Ti alloys to satisfy the ever-increasing need for enhanced biomedical products. In this study, we quantitatively determined the relationships between porosity, yield strength, and Young's modulus of SLM-prepared TNTZ lattices. The study constitutes a critical step toward understanding the behavior of the lattice and eventually enables tuning the Young's modulus to match that of human bones. Fatigue properties were also investigated on as-printed lattices in terms of the stress limit. The biocompatibility study included a routine evaluation of the relative cell growth rate and a proteomics analysis using a common mouse fibroblast cell line, L929. The results indicated that the as-printed TNTZ samples exhibited evidence of protein proliferation of the L929 cells, particularly P06733, and that those proteins are responsible for biological processes and molecular functions. They in turn may have promoted cell regeneration, cell motility, and protein binding, which at least partially explains the good biocompatibility of the as-printed TNTZ at the protein level. The study highlights the promising applications of additively manufactured TNTZ as a bone-replacing material from mechanical and biocompatibility perspectives.

Connective tissue growth factor stimulates osteosarcoma cell migration and induces osteosarcoma metastasis by upregulating VCAM-1 expression

Osteosarcoma is the most common bone malignancy that occurs in the young population. After osteosarcoma cells metastasize to the lung, prognosis is very poor owing to difficulties in early diagnosis and effective treatment. Recently, connective tissue growth factor (CTGF) was reported to be a critical contributor to osteosarcoma metastasis. However, the detailed mechanism associated with CTGF-directed migration in bone neoplasms is still mostly unknown. Through the in vivo and in vitro examination of osteosarcoma cells, this study suggests that VCAM-1 up-regulation and increased osteosarcoma cell migration are involved in this process. Antagonizing αvβ3 integrin inhibited cell migration. Moreover, FAK, PI3K, Akt and NF-κB activation were also shown to be involved in CTGF-mediated osteosarcoma metastasis. Taken together, CTGF promotes VCAM-1 production and further induces osteosarcoma metastasis via the αvβ3 integrin/FAK/PI3K/Akt/NF-κB signaling pathway, which could represent a promising clinical target to improve patient outcome.

CX3CL1 promotes MMP-3 production via the CX3CR1, c-Raf, MEK, ERK, and NF-κB signaling pathway in osteoarthritis synovial fibroblasts

Background

Osteoarthritis (OA) is a degenerative joint disease that affects the cartilage, synovium, and subchondral bone and is the leading cause of disability in older populations. Specific diagnostic biomarkers are lacking; hence, treatment options for OA are limited. Synovial inflammation is very common in OA joints and has been associated with both OA’s symptoms and pathogenesis. Confirming the role of the synovium in OA pathogenesis is a promising strategy for mitigating the symptoms and progression of OA. CX3CL1 is the only member of the CX3C class of chemokines that combines the properties of chemoattractants and adhesion molecules. CX3CL1 levels in the synovium and serum were both discovered to be positively associated with OA pathogenesis. CX3CL1 and its receptor CX3CR1 belong to a family of G protein-coupled receptors. Matrix metalloproteinases (MMPs), which are responsible for matrix degradation, play a crucial role in OA progression. The relationship between CX3CL1 and MMPs in the pathophysiology of OA is still unclear.

Methods

CX3CL1-induced MMP-3 production was assessed with quantitative real-time PCR and ELISA. The mechanisms of action of CX3CL1 in different signaling pathways were studied using western blot analysis, quantitative real-time PCR and ELISA. Neutralization antibodies of integrin were achieved to block the CX3CR1 signaling pathway. Luciferase assays were used to study NF-κB promoter activity.

Results

We investigated the signaling pathway involved in CX3CL1-induced MMP-3 production in osteoarthritis synovial fibroblasts (OASFs). CX3CL1 was found to induce MMP-3 production in a concentration-dependent and time-dependent manner. Using pharmacological inhibitors and CX3CR1 small interfering RNA to block CX3CR1 revealed that the CX3CR1 receptor was involved in the CX3CL1-mediated upregulation of MMP-3. CX3CL1-mediated MMP-3 production was attenuated by c-Raf inhibitors (GW5074) and MEK/ERK inhibitors (PD98059 and U0126). The OASFs were stimulated using CX3CL1-activated p65 phosphorylation.

Conclusions

Our results demonstrate that CX3CL1 activates c-Raf, MEK, ERK, and NF-κB on the MMP-3 promoter through CX3CR1, thus contributing to cartilage destruction during OA.

Fractalkine/CX3CL1 induced intercellular adhesion molecule-1-dependent tumor metastasis through the CX3CR1/PI3K/Akt/NF-κB pathway in human osteosarcoma

Osteosarcoma is the most common primary bone tumor in children and teens. The exact molecular mechanism underlying osteosarcoma progression still remains unclear. The CX3CL1/fractalkine has been implicated in various tumors but not in osteosarcoma. This study is the first to show that fractalkine promotes osteosarcoma metastasis by promoting cell migration. Fractalkine expression was higher in osteosarcoma cell lines than in normal osteoblasts. Fractalkine induced cell migration by upregulating intercellular adhesion molecule-1 (ICAM-1) expression via CX3CR1/PI3K/Akt/NF-κB pathway in human osteosarcoma cells. Knockdown of fractalkine expression markedly inhibited cell migration and lung metastasis in osteosarcoma. Finally, we showed a clinical correlation between CX3CL1 expression and ICAM-1 expression as well as tumor stage in human osteosarcoma tissues. In conclusion, our results indicate that fractalkine promotes cell migration and metastasis of osteosarcoma by upregulating ICAM-1 expression. Thus, fractalkine could serve a novel therapeutic target for preventing osteosarcoma metastasis.

The Use of Radiation Therapy in Well-Differentiated Soft Tissue Sarcoma of the Extremities: An NCDB Review

Objective. This study investigated patterns of utilization of radiation therapy (RT) and correlated this with overall survival by assessing patients with well-differentiated soft tissue sarcoma of the extremity (STS-E) in the National Cancer Database (NCDB). Methods. All patients diagnosed with well-differentiated STS-E between 1998 and 2006 were identified in the NCDB. Patients were stratified by use of surgery alone versus use of adjuvant RT after surgery and analyzed using multivariate analysis, Kaplan-Meier analysis, and propensity matching. Results. 2113 patients with well-differentiated STS-E were identified in the NCDB for inclusion with a mean follow-up time of 74 months. 69% of patients were treated with surgery alone, while 26% were treated with surgery followed by adjuvant RT. Patients undergoing amputation were less likely to receive adjuvant RT. There was no difference in overall survival between patients with well-differentiated STS treated with surgery alone and those patients who received adjuvant RT. Conclusions. In the United States, adjuvant RT is being utilized in a quarter of patients being treated for well-differentiated STS-E. While the use of adjuvant RT may be viewed as a means to facilitate limb salvage, this large national database review confirms no survival benefit, regardless of tumor size or margin status.

Cyr61 promotes epithelial-mesenchymal transition and tumor metastasis of osteosarcoma by Raf-1/MEK/ERK/Elk-1/TWIST-1 signaling pathway

Background

Osteosarcoma is the most common primary malignant tumor in children and young adults, and its treatment requires effective therapeutic approaches because of a high mortality rate for lung metastasis. Epithelial to mesenchymal transition (EMT) has received considerable attention as a conceptual paradigm for explaining the invasive and metastatic behavior during cancer progression. The cysteine-rich angiogenic inducer 61 (Cyr61) gene, a member of the CCN gene family, is responsible for the secretion of Cyr61, a matrix-associated protein that is involved in several cellular functions. A previous study showed that Cyr61 expression is related to osteosarcoma progression. In addition, Cyr61 could promote cell migration and metastasis in osteosarcoma. However, discussions on the molecular mechanism involved in Cyr61-regulated metastasis in osteosarcoma is poorly discussed.

Results

We determined that the expression level of Cyr61 induced cell migration ability in osteosarcoma cells. The Cyr61 protein promoted the mesenchymal transition of osteosarcoma cells by upregulating mesenchymal markers (TWIST-1 and N-cadherin) and inhibiting the epithelial marker (E-cadherin). Moreover, the Cyr61-induced cell migration was mediated by EMT. The Cyr61 protein elicited a signaling cascade that included αvβ5 integrin, Raf-1, mitogen-activated protein kinase (MEK), extracellular signal-regulated kinase (ERK), and Elk-1. The reagent or gene knockdown of these signaling proteins could inhibit Cyr61-promoted EMT in osteosarcoma. Finally, the knockdown of Cyr61 expression obviously inhibited cell migration and repressed mesenchymal phenotypes, reducing lung metastasis.

Conclusion

Our results indicate that Cyr61 promotes the EMT of osteosarcoma cells by regulating EMT markers via a signal transduction pathway that involves αvβ5 integrin, Raf-1, MEK, ERK, and Elk-1.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-236) contains supplementary material, which is available to authorized users.

Hyperthermia induces apoptosis through endoplasmic reticulum and reactive oxygen species in human osteosarcoma cells

Osteosarcoma (OS) is a relatively rare form of cancer, but OS is the most commonly diagnosed bone cancer in children and adolescents. Chemotherapy has side effects and induces drug resistance in OS. Since an effective adjuvant therapy was insufficient for treating OS, researching novel and adequate remedies is critical. Hyperthermia can induce cell death in various cancer cells, and thus, in this study, we investigated the anticancer method of hyperthermia in human OS (U-2 OS) cells. Treatment at 43 °C for 60 min induced apoptosis in human OS cell lines, but not in primary bone cells. Furthermore, hyperthermia was associated with increases of intracellular reactive oxygen species (ROS) and caspase-3 activation in U-2 OS cells. Mitochondrial dysfunction was followed by the release of cytochrome c from the mitochondria, and was accompanied by decreased anti-apoptotic Bcl-2 and Bcl-xL, and increased pro-apoptotic proteins Bak and Bax. Hyperthermia triggered endoplasmic reticulum (ER) stress, which was characterized by changes in cytosolic calcium levels, as well as increased calpain expression and activity. In addition, cells treated with calcium chelator (BAPTA-AM) blocked hyperthermia-induced cell apoptosis in U-2 OS cells. In conclusion, hyperthermia induced cell apoptosis substantially via the ROS, ER stress, mitochondria, and caspase pathways. Thus, hyperthermia may be a novel anticancer method for treating OS.

Transforming growth factor alpha promotes osteosarcoma metastasis by ICAM-1 and PI3K/Akt signaling pathway

Osteosarcoma is the most common primary malignancy of bone and is characterized by a high malignant and metastatic potential. Transforming growth factor alpha (TGF-α) is classified as the EGF (epidermal growth factor)-like family, which is involved in cancer cellular activities such as proliferation, motility, migration, adhesion and invasion abilities. However, the effect of TGF-α on human osteosarcoma is largely unknown. We found that TGF-α increased the cell migration and expression of intercellular adhesion molecule-1 (ICAM-1) in human osteosarcoma cells. Transfection of cells with ICAM-1 siRNA reduced TGF-α-mediated cell migration. We also found that the phosphatidylinositol 3'-kinase (PI3K)/Akt/NF-κB pathway was activated after TGF-α treatment, and TGF-α-induced expression of ICAM-1 and cell migration was inhibited by the specific inhibitors and siRNAs of PI3K, Akt, and NF-κB cascades. In addition, knockdown of TGF-α expression markedly decreased cell metastasis in vitro and in vivo. Our results indicate that TGF-α/EGFR interaction elicits PI3K and Akt activation, which in turn activates NF-κB, resulting in the expression of ICAM-1 and contributing the migration of human osteosarcoma cells.

CCN4 induces IL-6 production through αvβ5 receptor, PI3K, Akt, and NF-κB singling pathway in human synovial fibroblasts

Introduction

Osteoarthritis (OA) is the most common degenerative joint disease that is involved in the degradation of articular cartilage. The exact etiology of OA is not completely understood. CCN4 is related to up-regulation in the cartilage of patients with osteoarthritis. Previous studies have shown that CCN4 might be associated with the pathogenesis of OA, but the exact signaling pathways in CCN4-mediated IL-6 expression in synovial fibroblasts (SF) are largely unknown. Therefore, we explored the intracellular signaling pathway involved in CCN4-induced IL-6 production in human synovial fibroblast cells.

Methods

CCN4-induced IL-6 production was assessed with quantitative real-time qPCR and ELISA. The mechanisms of action of CCN4 in different signaling pathways were studied by using Western blotting. Neutralizing antibodies of integrin were used to block the integrin signaling pathway. Luciferase assays were used to study IL-6 and NF-κB promoter activity. Immunocytochemistry was used to examine the translocation activity of p65.

Results

Osteoarthritis synovial fibroblasts (OASFs) showed significant expression of CCN4 and the expression was higher than in normal SFs. OASF stimulation with CCN4 induced concentration- and time-dependent increases in IL-6 production. Pretreatment of OASFs with αvβ5 but not α5β1 and αvβ3 integrin antibodies reduced CCN4-induced IL-6 production. CCN4-mediated IL-6 production was attenuated by PI3K inhibitor (LY294002 and Wortmannin), Akt inhibitor (Akti), and NF-κB inhibitor (PDTC and TPCK). Stimulation of cells with CCN4 also increased PI3K, Akt, and NF-κB activation.

Conclusions

Our results suggest that CCN4 activates αvβ5 integrin, PI3K, Akt, and NF-κB pathways, leading to up-regulation of IL-6 production. According to our results, CCN4 may be an appropriate target for drug intervention in OA in the future.

HMGB-1 induces IL-6 production in human synovial fibroblasts through c-Src, Akt and NF-κB pathways

High mobility group box chromosomal protein 1 (HMGB-1) is a widely studied, ubiquitous nuclear protein that is present in eukaryotic cells, and plays a crucial role in inflammatory response. However, the effects of HMGB-1 on human synovial fibroblasts are largely unknown. In this study, we investigated the intracellular signaling pathway involved in HMGB-1-induced IL-6 production in human synovial fibroblast cells. HMGB-1 caused concentration- and time-dependent increases in IL-6 production. HMGB-1-mediated IL-6 production was attenuated by receptor for advanced glycation end products (RAGE) monoclonal antibody (Ab) or siRNA. Pretreatment with c-Src inhibitor (PP2), Akt inhibitor and NF-κB inhibitor (pyrrolidine dithiocarbamate and L-1-tosylamido-2-phenylenylethyl chloromethyl ketone) also inhibited the potentiating action of HMGB-1. Stimulation of cells with HMGB-1 increased the c-Src and Akt phosphorylation. HMGB-1 increased the accumulation of p-p65 in the nucleus, as well as NF-κB luciferase activity. HMGB-1-mediated increase of NF-κB luciferase activity was inhibited by RAGE Ab, PP2 and Akt inhibitor or RAGE siRNA, or c-Src and Akt mutant. Our results suggest that HMGB-1-increased IL-6 production in human synovial fibroblasts via the RAGE receptor, c-Src, Akt, p65, and NF-κB signaling pathways.

WISP-1 increases MMP-2 expression and cell motility in human chondrosarcoma cells

Chondrosarcoma is a type of highly malignant tumor with a potent capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. WISP-1 is a cysteine-rich protein that belongs to the CCN (Cyr61, CTGF, Nov) family of matricellular proteins. However, the effect of WISP-1 on migration activity in human chondrosarcoma cells is mostly unknown. Here we found that WISP-1 increased the migration and expression of matrix metalloproteinase (MMP)-2 in human chondrosarcoma cells (JJ012 cells). We also found that human chondrosarcoma tissues had significant expression of the WISP-1 which was higher than that in normal cartilage. α5β1 monoclonal antibody and MAPK kinase (MEK) inhibitors (PD98059 and U0126) inhibited the WISP-1-induced increase of the migration and MMP-2 up-regulation of chondrosarcoma cells. WISP-1 stimulation increased the phosphorylation of focal adhesion kinase (FAK), MEK and extracellular signal-regulated kinase (ERK). In addition, NF-κB inhibitors also suppressed the cell migration and MMP-2 expression enhanced by WISP-1. Moreover, WISP-1 increased NF-κB luciferase activity and binding of p65 to the NF-κB element on the MMP-2 promoter. Taken together, our results indicated that WISP-1 enhances the migration of chondrosarcoma cells by increasing MMP-2 expression through the α5β1 integrin receptor, FAK, MEK, ERK, p65 and NF-κB signal transduction pathway.

Efficient derivation and concise gene expression profiling of human embryonic stem cell-derived mesenchymal progenitors (EMPs)

New potential sources of stem cells for clinical application include bone marrow mesenchymal stem cells (BMMSCs), human embryonic stem cells (hESCs), and induced pluripotent stem cells (iPS). However, each source is not without its own concerns. While research continues in an effort to overcome these problems, the generation of mesenchymal progenitors from existing hESC lines may circumvent many of these issues. We report here a simple and efficient method of generating hESC-derived mesenchymal progenitors (EMPs) and transcriptome profiling using a concise, custom-designed, oligomnucleotide gene expression microarray. Characterization of EMPs shows that these cells are similar to BMMSCs in terms of differentiation capacity as well as cell surface marker expression. In addition, EMPs express several ESC markers and HLA-G, a nonclassical MHC class I molecule with immunomodulatory properties. Morevoer, EMPs possess significantly enhanced proliferative ability over BMMSCs during which karyotypic stability was maintained. Although derived from hESCs, EMPs do not form any tumors in immunocompromised mice. To efficiently profile gene expression in multiple samples, we designed an oligoarray to probe just over 11,000 genes highly expressed in stem cells. We found that the transcriptome of EMPs is more similar to BMMSCs than hESCs. Both cell types highly express genes involved in processes related to the cytoskeleton, extracellular matrix, and cell adhesion, but EMPs show higher expression of genes involved in cell proliferation whereas BMMSCs showed higher expression of immune-related genes. Based on our data, EMPs may be an accessible source of mesenchymal progenitor for therapeutic use.

TNF-α increases αvβ3 integrin expression and migration in human chondrosarcoma cells

Chondrosarcoma is a type of highly malignant tumour with a potent capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. Tumour necrosis factor (TNF)-α is a key cytokine involved in inflammation, immunity, cellular homeostasis and tumour progression. Integrins are the major adhesive molecules in mammalian cells and have been associated with metastasis of cancer cells. However, the effects of TNF-α in migration and integrin expression in chondrosarcoma cells are largely unknown. In this study, we found that TNF-α increased the migration and the expression of αvβ3 integrin in human chondrosarcoma cells. Activations of MAPK kinase (MEK), extracellular signal-regulating kinase (ERK) and nuclear factor-κB (NF-κB) pathways after TNF-α treatment were demonstrated, and TNF-α-induced expression of integrin and migration activity was inhibited by the specific inhibitor and mutant of MEK, ERK and NF-κB cascades. Taken together, our results indicated that TNF-α enhances the migration of chondrosarcoma cells by increasing αvβ3 integrin expression through the MEK/ERK/NF-κB signal transduction pathway.

The metastasectomy and timing of pulmonary metastases on the outcome of osteosarcoma patients

Background:

The author intended to clarify the therapeutic effect and prognostic factors of metastasectomy and timing of pulmonary metastases in osteosarcoma patents.

Methods:

Data was obtained retrospectively on all consecutive osteosarcoma patients from 1985 to 2005 in author’s institute. Fifty-two patients with pulmonary nodules were identified, including 24 patients undergoing pulmonary metastasectomy treatment. These patients were categorized into four groups: group 1, patients with lung metastases at the initial presentation; group 2, lung metastases identified during the period of pre-operative chemotherapy; group 3, lung metastases identified during period of the post-operative che motherapy; group 4, lung metastases identified after therapy for the primary osteosarcoma completed.

Results:

In our study, the 2-, 3-, and 5-year overall survival rates for 52 patients were 49%, 39% and 20%. The 2-year overall survival rates were 18% for group 1, 32% for group 3, and 70% for group 4 (p < 0.001). The 5-year overall survival rate was 34% for group 4. Patients who underwent metastesectomy showed a better survival outcome as compared with the patients not undergoing metastasectomy (p = 0.003). The 2-year and 5-year overall survival rates of only one lung metastatic nodule were 62% and 50%, and for initially multiple lung metastatic nodules, 45% and 5%, respectively. In addition, the patients presented with lung metastases had a worse prognosis as compared with those without initial lung metastases (p = 0.0001).

Conclusions:

The patients having single metastatic nodule showed a better prognosis than those with multiple lung nodules. Furthermore, those patients who underwent metastasectomy survived longer than those not undergoing metastasectomy. Patients who had late metastases after complete chemotherapy had a better prognosis; whereas those who had metastases identified at the initial presentation predicted a poor prognosis.

Ultrasound increased BMP-2 expression via PI3K, Akt, c-Fos/c-Jun, and AP-1 pathways in cultured osteoblasts

It has been shown that ultrasound (US) stimulation accelerates fracture healing in the animal models and in clinical studies. Bone morphogenetic protein (BMP) is a crucial mediator in bone formation during fracture healing. Here we found that US stimulation increased BMP-2 expression but not other BMPs. US induced BMP-2 transcription is mediated by AP-1 element but not estrogen receptor response element and GC-rich Sp1 response element. Pretreatment of osteoblasts with phosphatidylinositol 3-kinase (PI3K) inhibitor (Ly294002) and Akt inhibitor inhibited the potentiating action of US; these results were further substantiated by transfecting with the dominant negative mutants of p85 and Akt. US stimulation increased the phosphorylation of p85 subunit of PI3K and serine 473 of Akt. Transfection of osteoblasts with c-Fos and c-Jun antisense oligonucleotide also reduced US-increased BMP-2 expression. US-increased the binding of c-Fos and c-Jun to the AP-1 element on the BMP-2 promoter and the enhancement of AP-1 luciferase activity was inhibited by Ly294002 and Akt inhibitor. Our results suggest that US increased BMP-2 expression in osteoblasts via the PI3K, Akt, c-Fos/c-Jun, and AP-1 signaling pathway.

Bone morphogenetic protein-2 enhances the motility of chondrosarcoma cells via activation of matrix metalloproteinase-13

Chondrosarcoma is a low-grade sarcoma characterized by developing metastases and high local recurrence rate. Bone morphogenetic protein-2 (BMP-2) plays an essential role in tumor progression and metastasis. Here we found that BMP-2 induced the migration of human chondrosarcoma cells (JJ012 cells). BMP-2 also increased the secretion of metalloproteinase-13 (MMP-13) in JJ012 cells, as shown by reverse transcriptase-polymerase chain reaction, western blot and zymographic analysis. The MMP-13 small interfering RNA inhibited the BMP-2-induced MMP-13 expression and thereby significantly inhibited the BMP-2-induced cell migration. Furthermore, phosphatidylinositol 3-kinase inhibitor (PI3K; Ly294002) or Akt inhibitor suppressed BMP-2-induced MMP-13 mRNA expression. Transient transfection with dominant negative p85 and Akt mutant also showed that the PI3K/Akt signaling pathway was involved in BMP-2-induced MMP-13 expression. In addition, AP-1 decoy oligodeoxynucleotide also suppressed the MMP-13 promoter activity enhanced by BMP-2. Moreover, BMP-2 increased the binding of c-Fos and c-Jun to the AP-1 element on the MMP-13 promoter. Taken together, our results indicated that BMP-2 enhanced the invasiveness of chondrosarcoma cells by increasing MMP-13 expression through the PI3K, Akt, c-Fos/c-Jun and AP-1 signal transduction pathway.

AMP-activated protein kinase is involved in COX-2 expression in response to ultrasound in cultured osteoblasts

It has been shown that ultrasound (US) stimulation accelerates fracture healing in the animal models and in clinical studies. Cyclooxygenase-2 (COX-2) is a crucial mediator in mechanically induced bone formation. AMP-activated protein kinase (AMPK) has reported to sense and regulate the cellular energy status in various cell types. Here we found that US-mediated COX-2 expression was attenuated by LKB1 and AMPKalpha1 small interference RNA (siRNA) in human osteoblasts. Pretreatment of osteoblasts with AMPK inhibitor (araA and compound C), p38 inhibitor (SB203580), NF-kappaB inhibitor (PDTC), IkappaB protease inhibitor (TPCK) and NF-kappaB inhibitor peptide also inhibited the potentiating action of US. US increased the kinase activity and phosphorylation of LKB1, AMPK and p38. Stimulation of osteoblasts with US activated IkappaB kinase alpha/beta (IKKalpha/beta), IkappaBalpha phosphorylation, IkappaBalpha degradation, p65 phosphorylation at Ser(276), p65 and p50 translocation from the cytosol to the nucleus, and kappaB-luciferase activity. US-mediated an increase of IKKalpha/beta activity, kappaB-luciferase activity and p65 and p50 binding to the NF-kappaB element was inhibited by araA, SB203580 and LKB1 siRNA. Our results suggest that US increased COX-2 expression in osteoblasts via the LKB1/AMPKalpha1/p38/IKKalphabeta and NF-kappaB signaling pathway.

Loosening of total hip arthroplasty with a prosthesis employing a skirted femoral head

In total hip arthroplasty, a modular femoral head with a flange increases the head-neck strength and compensates the leg length, but results in a decreased head-to-neck diameter ratio. Studies have shown increased chance of impingement and incidence of dislocation associated with a skirted femoral head component. However, the relation between implant loosening and the skirted neck has not been well demonstrated. We report a 41-year-old male patient with aseptic loosening of total hip arthroplasty due to osteolysis of both acetabular and femoral components 5 years after surgery. The retrieved prostheses demonstrated polyethylene wear due to impingement of the skirted head during hip flexion. Pathologic examination showed prominent foreign body reaction. Prosthetic impingement occurs due to malposition of components and extreme posture. A decreased head-to-neck diameter ratio further compromises prosthetic range of motion. A skirted femoral head component should be used with caution.

Ultrasound examination of patellar tendon after harvest for anterior cruciate ligament reconstruction

BACKGROUND AND PURPOSE

Reconstruction of ruptured anterior cruciate ligament (ACL) using the middle-third of the patellar tendon has become an established procedure. However, current studies of donor site morbidity have reported discrepant results. This study used ultrasound imaging to evaluate morphologic changes in the patellar tendon after harvest for ACL reconstruction.

METHODS

Twenty-nine patients who had undergone successful ACL reconstruction with patellar tendon graft more than 1 year previously were enrolled in the study. Ultrasound imaging was used to compare the width, thickness, and tissue reaction of patellar tendons between the operated and contralateral sides.

RESULTS

The operated side was 4.8% wider on average than the contralateral side (p < 0.05). The operated side was also 58.3% thicker on average (p < 0.0001), with irregular margins and heterogenous echogenecity.

CONCLUSION

The donor site of the patellar tendon was significantly wider and thicker and was heterogenous when examined on sonogram more than 1 year postoperatively.

Anterior tibia spine fracture in children: follow-up evaluation by biomechanical studies

BACKGROUND

The treatment of anterior tibial spine (ATS) fracture in children is in controversy. Previous studies have shown that most of the children who sustained ATS fractures have objective evidence of the anterior cruciate ligament (ACL) laxity at follow-up, but detailed biomechanical analysis of the knee joint has seldom been performed.

METHODS

Eight ATS fractures in children at a mean age of 12 years were treated from 1989 to 1994. Two were of Meyer's classification type I, 3 were of type II, and 3 were of type III. The treatment varied from casting to open reduction & internal fixation (ORIF) by pulling through suture or biofix absorbable screw. Patients were followed with radiological, clinical and biomechanical analysis. KT 1000 knee arthrometer was used to evaluate the laxity of ACL. Cybex isokinetic machine was used to evaluate knee extensor and flexor strength.

RESULTS

During an average follow-up period of 47 months, all fractures showed to unite well on X-ray except 1 untreated type I fracture who had malunion. Only one had subjective complaint of instability, but 3 had clinical signs of instability. Objective evidence of laxity, determined by KT-1000 arthrometer, was noted in 4 patients. Decreased muscle strength, determined by Cybex isokinetic machine, was more prominent in hamstrings than in quadriceps.

CONCLUSIONS

Patients with milder ATS fracture (type I & II), if treated inappropriately, may still result in ACL laxity and knee muscle strength deficiency. Type III ATS fractures, if treated well by ORIF, tend to recover nearly normal ACL function and muscle strength.

Intrafamilial transmission of hepatitis C virus in hemodialysis patients

The prevalence of hepatitis C virus (HCV) infection in chronic hemodialysis patients ranges from 20 to 50% and these patients may serve as a reservoir of infection for their household contacts. The aim of this study was to investigate the prevalence of anti-HCV in hemodialysis patients and their families, and to evaluate possible routes of infection. One hundred eighty-six family members of 84 hemodialysis patients and 529 healthy adults were enrolled. The family members consisted of 50 spouses, 96 children, 11 parents, 29 siblings, and other relatives living together with the patients. Serum samples were collected for testing anti-HCV. Exposure to risk factors was obtained by a questionnaire and an interview. The results showed that prevalence of anti-HCV in hemodialysis patients was 44%, whereas in family members it was 5.4%, not significantly different from that of age-matched healthy adults (standardized morbidity rate = 1.51, P = 0.390). The anti-HCV rate in family members tended to increase with age, and a spouse of an infected hemodialysis patient had a higher risk of HCV infection than other family members (15% vs. 2.6%, odds ratio 6.6, P = 0.058). Except for the age factor, no difference was found between seropositive and seronegative family members with respect to risk factors such as blood transfusion, surgery, frequent injections, dental procedures, or acupuncture. It was concluded that, although the anti-HCV positivity of hemodialysis patients is high, the risk of HCV infection for their family members is not higher than that of the general population. Among family members, spouses of seropositive hemodialysis patients have the highest risk of HCV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous ambulatory peritoneal dialysis in the elderly: a seven-year experience

This is a retrospective comparison of the status among the elderly (> or = 60 years, 23 patients) and younger patients (< 60 years, 31 cases) who initiated continuous ambulatory peritoneal dialysis (CAPD) between January 1986 and December 1992 at the National Taiwan University Hospital. The distribution of underlying renal diseases differed in the two groups with diabetes (56%) as the most common disease in the elderly, in contrast to glomerulonephritis (60%) in the younger patients. Haemodialysis intolerance and patient preference were the main reasons leading to the use of CAPD in both groups. Social rehabilitation status was poorer in the elderly group. The difference in cumulative risk of the first peritonitis episode and the technique failure rate were not statistically significant. The major causes of mortality were of vascular origin in both groups. In conclusion, similarities in the technique failure rate and the cumulative risk of peritonitis imply that CAPD is an acceptable alternative long-term dialysis therapy for geriatric patients.

Measurement of Chinese lumbar pedicles: with special reference to transpedicular screw fixation

BACKGROUND

Thorough understanding of the morphometric parameters of the lumbar pedicles is essential for transpedicular screw fixation. The purpose of this study is to establish a database for proper spinal instrumentations in Chinese patients.

METHODS

A total of 764 pedicles (L2-S1) were measured from spinal computed tomography (CT) of 100 Chinese volunteers. Parameters related to transpedicular fixation include pedicle width (PW), pedicle transverse angle (PTA), pedicle angle measured from the entry point of Roy-Camille through the midpoint of the pedicle (PPA), screw insertion depths to the anterior cortex from the entry point of Roy-Camille along the line parallel to the midsagittal line (PPLP) and from the entry point of Magerl along the pedicle axis (PPLS).

RESULTS

The mean age of the volunteers was 46.2 years. The average PWs from L2 to S1 were: 0.85 +/- 0.15 cm for L2, 0.92 +/- 0.22 cm for L3, 1.19 +/- 0.24 cm for L4, 1.70 +/- 0.28 cm for L5 and 2.31 +/- 0.35 cm for S1. The average PTAs from L2 to S1 were: 13.9 degrees +/- 4.9 degrees for L2, 13.4 degrees +/- 5.1 degrees for L3, 16.2 degrees +/- 5.9 degrees for L4, 27.8 degrees +/- 7.2 degrees for L5 and 44.0 degrees +/- 8.4 degrees for S1. The average PPAs from L2 to S1 were: 5.3 degrees +/- 2.4 degrees for L2, 6.3 degrees +/- 2.2 degrees for L3, 7.2 degrees +/- 2.5 degrees for L4, 10.1 degrees +/- 3.6 degrees for L5 and 17.0 degrees +/- 4.8 degrees for S1. The average PPLPs from L2 to S1 were: 5.64 +/- 0.82 cm for L2, 5.05 +/- 0.62 cm for L3, 4.99 +/- 0.89 cm for L4, 4.42 +/- 0.77 cm for L5 and 4.23 +/- 0.72 cm for S1. The average PPLSs from L2 to S1 were: 5.75 +/- 0.72 cm for L2, 5.24 +/- 0.75 cm for L3, 5.27 +/- 0.84 cm for L4, 4.88 +/- 0.72 cm for L5 and 4.99 +/- 0.72 cm for S1.

CONCLUSIONS

Transpedicular screw fixation should be tailored on individual basis. Though variation exists, no sufficient evidence can be found to suggest major morphometric differences of the Chinese lumbar pedicles from the studies in the English literature.

Peritoneopericardial communication after pericardiocentesis in a patient on continuous ambulatory peritoneal dialysis with dialysis pericarditis

A male patient aged 41 years had dialysis pericarditis with massive pericardial effusion in his 6-year on continuous ambulatory peritoneal dialysis (CAPD). Intensive hemodialysis failed to resolve the pericardial effusion. Pericardiocentesis via a subxiphoid approach was performed with placement of a pigtail catheter for drainage. A communication between peritoneal and pericardial cavities occurred, resulting in the leakage of the peritoneal dialysate into pericardial sac which was confirmed by a 99mTc radionuclide scan. The fistula healed after removal of the catheter and discontinuation of CAPD. We suggest that pericardiocentesis via a subxiphoid approach for pericardial effusion should be cautiously exercised in CAPD cases for fear of peritoneopericardial fistula.

Blood pressure response to angiotensin converting enzyme inhibitor in essential hypertension: its relation to the renin status and natriuresis during acute sodium loading

We examined the antihypertensive response to enalapril and its relation to the changes of the renin-angiotensin-aldosterone axis (RAA) in essential hypertensive patients. The responders, whose blood pressure reduced after enalapril administration, had significant elevation of plasma renin activity after enalapril (7.5 +/- 4.0 to 31.9 +/- 10 ng/mL/h, p < 0.05). There was no significant change in the plasma renin activity of the nonresponders (3.0 +/- 1.0 to 5.6 +/- 1.9 ng/mL/h). Natriuretic response to acute salt loading was compared between the two subgroups. The natriuresis on acute salt loading of nonresponders was better than that of the responders (82.9 +/- 13.2 vs 44.5 +/- 5.7 mmol/4h, p < 0.05). These results imply that the RAA and extracellular fluid volume both contribute in different ways to the maintenance of high blood pressure in different subgroups of essential hypertension.