Dickkopf-1 (DKK1) blockade mitigates osteogenesis imperfecta (OI) related bone disease.

BACKGROUND: The current treatment of osteogenesis imperfecta (OI) is imperfect. Our study thus delves into the potential of using Dickkopf-1 antisense (DKK1-AS) to treat OI. METHODS: We analysed serum DKK1 levels and their correlation with lumbar spine and hip T-scores in OI patients. Comparative analyses were conducted involving bone marrow stromal cells (BMSCs) and bone tissues from wild-type mice, untreated OI mice, and OI mice treated with DKK1-ASor DKK1-sense (DKK1-S). RESULTS: Significant inverse correlations were noted between serum DKK1 levels and lumbar spine (correlation coefficient = - 0.679, p = 0.043) as well as hip T-scores (correlation coefficient = - 0.689, p = 0.042) in OI patients. DKK1-AS improved bone mineral density (p = 0.002), trabecular bone volume/total volume fraction (p < 0.001), trabecular separation (p = 0.010), trabecular thickness (p = 0.001), trabecular number (p < 0.001), and cortical thickness (p < 0.001) in OI mice. DKK1-AS enhanced the transcription of collagen 1α1, osteocalcin, runx2, and osterix in BMSC from OI mice (all p < 0.001), resulting in a higher von Kossa-stained matrix area (p < 0.001) in ex vivo osteogenesis assays. DKK1-AS also reduced osteoclast numbers (p < 0.001), increased ß-catenin and T-cell factor 4 immunostaining reactivity (both p < 0.001), enhanced mineral apposition rate and bone formation rate per bone surface (both p < 0.001), and decreased osteoclast area (p < 0.001) in OI mice. DKK1-AS upregulated osteoprotegerin and downregulated nuclear factor-kappa B ligand transcription (both p < 0.001). Bone tissues from OI mice treated with DKK1-AS exhibited significantly higher breaking force compared to untreated OI mice (p < 0.001). CONCLUSIONS: Our study elucidates that DKK1-AS has the capability to enhance bone mechanical properties, restore the transcription of osteogenic genes, promote osteogenesis, and inhibit osteoclastogenesis in OI mice.

Proteomic and phosphoproteomic characterization of cardiovascular tissues after long term exposure to simulated space radiation.

Introduction: It may take decades to develop cardiovascular dysfunction following exposure to high doses of ionizing radiation from medical therapy or from nuclear accidents. Since astronauts may be exposed continually to a complex space radiation environment unlike that experienced on Earth, it is unresolved whether there is a risk to cardiovascular health during long-term space exploration missions. Previously, we have described that mice exposed to a single dose of simplified Galactic Cosmic Ray (GCR5-ion) develop cardiovascular dysfunction by 12 months post-radiation. Methods: To investigate the biological basis of this dysfunction, here we performed a quantitative mass spectrometry-based proteomics analysis of heart tissue (proteome and phosphoproteome) and plasma (proteome only) from these mice at 8 months post-radiation. Results: Differentially expressed proteins (DEPs) for irradiated versus sham irradiated samples (fold-change ≥1.2 and an adjusted p-value of ≤0.05) were identified for each proteomics data set. For the heart proteome, there were 87 significant DEPs (11 upregulated and 76 downregulated); for the heart phosphoproteome, there were 60 significant differentially phosphorylated peptides (17 upregulated and 43 downregulated); and for the plasma proteome, there was only one upregulated protein. A Gene Set Enrichment Analysis (GSEA) technique that assesses canonical pathways from BIOCARTA, KEGG, PID, REACTOME, and WikiPathways revealed significant perturbation in pathways in each data set. For the heart proteome, 166 pathways were significantly altered (36 upregulated and 130 downregulated); for the plasma proteome, there were 73 pathways significantly altered (25 upregulated and 48 downregulated); and for the phosphoproteome, there were 223 pathways significantly affected at 0.1 adjusted p-value cutoff. Pathways related to inflammation were the most highly perturbed in the heart and plasma. In line with sustained inflammation, neutrophil extracellular traps (NETs) were demonstrated to be increased in GCR5-ion irradiated hearts at 12-month post irradiation. NETs play a fundamental role in combating bacterial pathogens, modulating inflammatory responses, inflicting damage on healthy tissues, and escalating vascular thrombosis. Discussion: These findings suggest that a single exposure to GCR5-ion results in long-lasting changes in the proteome and that these proteomic changes can potentiate acute and chronic health issues for astronauts, such as what we have previously described with late cardiac dysfunction in these mice.

Computer-assisted image analysis of preexisting histological patterns of the cephalic vein to predict wrist arteriovenous fistula non-maturation.

BACKGROUND: We used computer-assisted image analysis to determine whether preexisting histological features of the cephalic vein influence the risk of non-maturation of wrist fistulas. METHODS: This study focused on patients aged 20-80 years who underwent their first wrist fistula creation. A total of 206 patients participated, and vein samples for Masson's trichrome staining were collected from 134 patients. From these, 94 patients provided a complete girth of the venous specimen for automatic image analysis. Maturation was assessed using ultrasound within 90 days after surgery. RESULTS: The collagen to muscle ratio in the target vein, measured by computer-assisted imaging, was a strong predictor of non-maturation in wrist fistulas. Receiver operating characteristic analysis revealed an area under the curve of 0.864 (95% confidence interval of 0.782-0.946, p < 0.001). The optimal cut-off value for the ratio was 1.138, as determined by the Youden index maximum method, with a sensitivity of 89.0% and specificity of 71.4%. For easy application, we used a cutoff value of 1.0; the non-maturation rates for patients with ratios >1 and ≤ 1 were 51.7% (15 out of 29 patients) and 9.2% (6 out of 65 patients), respectively. Chi-square testing revealed significantly different non-maturation rates between the two groups (X2 (1, N = 94) = 20.9, p < 0.01). CONCLUSION: Computer-assisted image interpretation can help to quantify the preexisting histological patterns of the cephalic vein, while the collagen-to-muscle ratio can predict non-maturation of wrist fistula development at an early stage.

Impact of Previous Conventional Cardiac Surgery on the Clinical Outcomes After Heart Transplantation.

The impact of the type, purpose, and timing of prior surgery on heart transplantation (HT) remains unclear. This study investigated the influence of conventional cardiac surgery (PCCS) on HT outcomes. This study analyzed HTs performed between 1999 and 2019 at a single institution. Patients were categorized into two groups: those with and without PCCS. Short-term outcomes, including post-transplant complications and mortality rates, were evaluated. Cox proportional and Kaplan-Meier survival analyses were used to identify risk factors for mortality and assess long-term survival, respectively. Of 368 patients, 29% had PCCS. Patients with PCCS had a higher incidence of post-transplant complications. The in-hospital and 1 year mortality rates were higher in the PCCS group. PCCS and cardiopulmonary bypass time were significant risk factors for 1 year mortality (hazard ratios = 2.485 and 1.005, respectively). The long-term survival rates were lower in the PCCS group, particularly in the first year. In sub-analysis, patients with ischemic cardiomyopathy and PCCS had the poorest outcomes. The era of surgery and timing of PCCS in relation to HT did not significantly impact outcomes. In conclusion, PCCS worsen the HT outcomes, especially in patients with ischemic etiology. However, the timing of PCCS and era of HT did not significantly affect this concern.

Subclinical myocardial injury increases the risk of heart failure in patients with and without type 2 diabetes post-acute coronary syndrome.

BACKGROUND: Little is known about the effect of subclinical myocardial injury (sMi) on heart failure (HF) risk after acute coronary syndrome (ACS). We examined the frequency patterns of sMi after ACS among patients with and without diabetes mellitus (DM), and the influence of sMis on HF risk at 1 year. METHODS: Fifty patients with ACS who underwent revascularization were prospectively enrolled. After discharge, serial study visits were conducted and high-sensitivity cardiac troponin T (hs-TnT) levels were checked at 3-month intervals for 1 year. sMi was defined as hs-TnT ≥14 ng/L without clinical symptoms. The primary endpoint was a composite of post-ACS chronic HF or significant left ventricular (LV) dysfunction without HF symptoms. A multivariable logistic regression model was used for risk evaluation. RESULTS: The mean patient age was 58 years, and 90% were men. Overall, 44% of patients had DM, and the median LV ejection fraction at discharge was 56%. Patients with DM had a higher incidence of sMi than those without DM (63.6% vs. 32.1%, P < 0.05). sMi occurred at least twice in most patients, and the prevalence declined over time in DM, but not in non-DM. Fourteen patients (28%) met the primary endpoint at 1 year, and the risk was higher in patients with DM (odds ratio: 4.99) and patients with sMi (odds ratio: 6.26). However, sMi was not a mediator of the association between DM and HF risk. CONCLUSIONS: Patients with DM had a higher incidence of sMi. Nonetheless, sMi increased the risk of HF after ACS, irrespective of diabetes status.

Validation of the European system for cardiac operative risk evaluation II in a large Taiwan cardiac surgical centre.

BACKGROUND: The European System for Cardiac Operative Risk Evaluation (EuroSCORE II) is a well-established scoring system for predicting mortality in cardiac surgery. This system was derived predominantly from a European patient cohort; however, no validation of this system has been conducted in Taiwan. We sought to assess the performance of EuroSCORE II at a tertiary centre. METHODS: The 2161 adult patients receiving cardiac surgery between 2017 and 2020 in our institution were included. RESULTS: Overall, the in-hospital mortality rate was 7.89%. The performance of EuroSCORE II was assessed using the area under the receiver operator curve (AUC) for discrimination and the Hosmer-Lemeshow (H-L) test for calibration. Data were analysed for type of surgery, risk stratification, and status of the operation. EuroSCORE II had good discriminative power (AUC=0.854, 95% Confidence Interval (CI): 0.822-0.885) and good calibration (χ2=5.19, p=0.82) for all types of surgery except ventricular assist devices (AUC=0.618, 95% CI: 0.497-0.738). EuroSCORE II also showed good calibration for most types of surgery except coronary artery bypass surgery (CABG) combined procedure (P=0.033), heart transplantation (HT) (P=0.017), and urgent operation (P=0.041). EuroSCORE II significantly underestimated the risk for CABG combined procedure and urgent operations, and overestimated the risk for HT. CONCLUSION: EuroSCORE II had satisfactory discrimination and calibration power to predict surgical mortality in Taiwan. However, the model is poorly calibrated for CABG combined procedure, HT, urgent operation, and, likely, lower- and higher-risk patients.

A Randomized Trial of Postoperative Handgrip Exercises for Fistula Maturation in Patients With Newly Created Wrist Radiocephalic Arteriovenous Fistulas.

Introduction: We aimed to substantiate the benefit of postoperative handgrip exercises (HGEs) in enhancing the maturation of an arteriovenous wrist fistula. Methods: We randomly assigned 119 patients aged 20 to 80 years who had wrist arteriovenous fistulas (AVFs) to undergo either a basic HGE program (group A), an advanced program (group B), or an advanced-plus upper arm banding program (group C). Outcomes were assessed by ultrasonographic evaluation of the diameter and flow at each follow-up. The attending nephrologist decided the clinical use of the fistula. Results: We identified no significant differences among the HGE groups in the mean diameter and blood flow 14, 30, 60, and 90 days after the creation of the wrist AVF (P = 0.55, 0.88, 0.21, and 0.19 for the diameter; 0.94, 0.81, 0.49, and 0.56 for the flow, respectively). The intent-to-treat analysis also found no difference in the clinical use of fistulas for hemodialysis (HD) (P = 0.997). Conclusion: In patients with a newly created wrist AVF, advancing frequency, with or without adding intensity using an upper arm tourniquet, of postoperative HGEs did not enhance the growth of the fistula or increase the rate of clinical use over 3 months. (ClinicalTrials.gov ID: NCT03077815).

Streptococcus mutans PrsA mediates AtlA secretion contributing to extracellular DNA release and biofilm formation in the pathogenesis of infective endocarditis.

The role of secretion chaperone-regulated virulence proteins in the pathogenesis of infective endocarditis (IE) induced by viridans streptococci such as Streptococcus mutans is unclear. In this study, we investigated the contribution of the foldase protein PrsA, a putative parvulin-type peptidyl-prolyl isomerase, to the pathogenesis of S. mutans-induced IE. We found that a prsA-deficient strain had reduced virulence in terms of formation of vegetation on damaged heart valves, as well as reduced autolysis activity, eDNA release and biofilm formation capacity. The secretion and surface exposure of AtlA in vitro was reduced in the prsA-deficient mutant strain, and complementation of recombinant AtlA in the culture medium restored a wild type biofilm phenotype of the prsA-deficient mutant strain. This result suggests that secretion and surface localization of AtlA is regulated by PrsA during biofilm formation. Together, these results demonstrate that S. mutans PrsA could regulate AtlA-mediated eDNA release to contribute to biofilm formation in the pathogenesis of IE.

Biomarker of neutrophil extracellular traps is associated with deep-seated infections and predicts mortality and cardiovascular morbidity in commensal streptococcal bacteremia.

BACKGROUND: Neutrophil extracellular traps (NETs) play important roles in sepsis and deep-seated infections, but whether NET formation correlates with clinical outcomes of patients with streptococcal bloodstream infections (BSIs) is unclear. METHODS: We analyzed serum levels of complexes of myeloperoxidase and DNA (MPO-DNA) in patients with streptococcal-BSIs. In vitro assay of NET induction by serum from BSI patients was performed. RESULTS: MPO-DNA values for the Streptococci-BSI group (n = 59) were significantly higher than those for healthy controls (p < 0.00001) and matched control groups (n = 59, p = 0.004). The rate of higher MPO-DNA levels (>1.87 µg/mL) were higher in abscess-prone streptococcal groups (streptococcus milleri group) (72.2% vs. 52.5%, p = 0.02). For patients with BSIs due to highly infective endocarditis (IE)-prone pathogens, the values of serum MPO-DNA were also higher in patients diagnosed of IE compared to their counterparts (p = 0.009). Notably, serum from patients with leukopenia could induce higher amounts of in vitro NET formation, despite having low MPO-DNA levels, suggesting that NET formation could be influenced by WBC counts. Therefore, we combined WBC counts with MPO-DNA to predict all-cause 30-day mortality in patients with commensal streptococcal-BSIs. The mortality risk was lowest among patients who had neither high MPO-DNA levels nor abnormal WBC counts (p = 0.058). Furthermore, this group of patients also had a favorable composite outcome consisting of major adverse cardiovascular events (MACE) and all-cause mortality (p = 0.026). CONCLUSION: Together, these study data suggested that serum MPO-DNA can be a biomarker for predicting a composite outcome consisting of MACE and all-cause mortality in patients with commensal streptococcal-BSIs.

Impact of Pretransplant Renal Replacement Therapy on Clinical Outcome After Isolated Heart Transplantation.

End stage renal disease (ESRD) is a contraindication to isolated heart transplantation (HT). However, heart candidates with cardiogenic shock may experience acute kidney injury and require renal replacement therapy (RRT) and isolated HT as a life-saving operation. The outcomes, including survival and renal function, are rarely reported. We enrolled 569 patients undergoing isolated HT from 1989 to 2018. Among them, 66 patients required RRT before HT (34 transient and 32 persistent). The survival was worse in patients with RRT than those without (65.2% vs 84.7%; 27.3% vs 51.1% at 1- and 10-year, p < 0.001 and p = 0.012, respectively). Multivariate Cox analysis identified pre-transplant hyperbilirubinemia (Hazard ratio (HR) 2.534, 95% confidence interval (CI) 1.098-5.853, p = 0.029), post-transplant RRT (HR 5.551, 95%CI 1.280-24.068, p = 0.022) and post-transplant early bloodstream infection (HR 3.014, 95%CI 1.270-7.152, p = 0.012) as independent risk factors of 1-year mortality. The majority of operative survivors (98%) displayed renal recovery after HT. Although patients with persistent or transient RRT before HT had a similar long-term survival, patients with persistent RRT developed a high incidence (49.2%) of dialysis-dependent ESRD at 10 years. In transplant candidates with pretransplant RRT, hyperbilirubinemia should be carefully re-evaluated for the eligibility of HT whereas prevention and management of bloodstream infection after HT improve survival.

Impact of pre-transplant bloodstream infection on clinical outcomes after heart transplantation.

BACKGROUND: Active bloodstream infection (BSI) is a contraindication for heart transplantation (HT). However, some critical patients with BSI may undergo HT as a life-saving procedure. We aimed to investigate the impact of pre-transplant BSI on the clinical outcomes after HT. METHODS: We enrolled 511 consecutive patients who underwent HT between 1999 and 2019. Patients were divided into two groups based on the presence of BSI within 30 days preoperatively. Forty-three patients (8.4%) with BSI who were clinically stable and had no metastatic infection were considered for HT on an individual basis. In-hospital mortality, incidence of early postoperative BSI, length of postoperative hospital stays, and long-term survival were compared between the groups. Logistic and Cox regression analyses were performed to identify risk factors for in-hospital and 1-year mortality. RESULTS: Patients with pre-transplant BSI had a high incidence of previous cardiopulmonary resuscitation, pre-transplant ventilator use, mechanical circulatory support use, renal replacement therapy, United Network for Organ Sharing status 1A, and a prolonged preoperative hospital waiting period. The in-hospital mortality rate was higher in patients with pre-transplant BSI (21% vs. 12%, p = .081), and the mortality rate was very high (33.3%) for those with BSI 0-15 days before HT. In addition, patients with pre-transplant BSI had a significantly longer postoperative hospital stay than patients in the control group. However, long-term survival was similar in both groups. CONCLUSIONS: Although pre-transplant BSI was associated with higher in-hospital mortality and prolonged postoperative hospital stay, patients who survived the early period had a similar long-term prognosis.

Malignant granular cell tumour at the interventricular septum.

Granular cell tumours are usually benign with a 1-2% incidence of malignancy. They are less sensitive to radiotherapy and chemotherapy and are treated by surgical excision. We report a case of a malignant granular cell tumour located at the interventricular septum.

Avoidance of intramedullary violation in computer-assisted total knee arthroplasty lowers the incidence of periprosthetic joint infection compared with conventional total knee arthroplasty: A propensity score matching analysis of 5342 cases.

BACKGROUND: Conventional total knee arthroplasty (CONV-TKA) inevitably perturbs femoral medullary canal, disturbs medullary micro-architecture and increases blood loss and inflammatory responses. We hypothesized that avoidance of intramedullary violation may lower the incidence of periprosthetic joint infection (PJI). The aim of this study was to verify whether computer-assisted total knee arthroplasty (CAS-TKA) lowers the incidence of PJI as compared with CONV-TKA. METHODS: A propensity score matching study of 5342 patients who underwent CAS-TKA (n = 1085) or CONV-TKA (n = 4257) for primary osteoarthritis of the knee from 2007 to 2015 in our institute was performed. Patients who underwent CAS-TKA were matched to those who received CONV-TKA at a 1:2 ratio according to demographics and comorbidities. PJI was defined according to the Musculoskeletal Infection Society diagnostic criteria from the 2013 International Consensus Meeting. RESULTS: After controlling potential risk factors, the use of CAS-TKA resulted in a lower incidence of PJI as compared with CONV-TKA [adjusted hazard ratio (HR), 0.42; 95% confidence interval (CI), 0.18-0.99]. The same trend in PJI reduction was observed with the usage of CAS-TKA under sensitivity testing [HR, 0.33; 95% CI, 0.12-0.95]. The cumulative incidence of PJI was lower in the CAS-TKA group than the CONV-TKA group (log-rank test, p = 0.013). CONCLUSION: Avoidance of intramedullary violation during TKA may play a pivotal role in lowering the incidence of PJI. The use of CAS-TKA can reduce the incidence of PJI, with a better survival rate in terms of being free of PJI, as compared with CONV-TKA.

Long-Term Clinical Outcomes of Fractional Flow Reserve-Guided Coronary Artery Revascularization in Chronic Kidney Disease.

Fractional flow reserve (FFR)-guided percutaneous coronary intervention has shown favorable long-term clinical outcomes. However, limited data exist evaluating the FFR assessment among the chronic kidney disease (CKD) population. The aim of this study was to evaluate the long-term clinical outcomes of FFR-guided coronary revascularization in patients with CKD. A total of 242 CKD patients who underwent FFR assessment were retrospectively analyzed. Patients were divided into two groups: revascularization (FFR ≤ 0.80) and non-revascularization (FFR > 0.80). The primary endpoint was the composite of cardiac death, non-fatal myocardial infarction, and target vessel failure (TVF). The key secondary endpoint was TVF. The Cox regression model was used for risk evaluation. With 91% of the ischemic vessels revascularized, the revascularization group had higher risks for both the primary endpoint (adjusted hazard ratio [aHR]: 2.06; 95% confidence interval [CI], 1.07-3.97; p = 0.030) and key secondary endpoint (aHR: 2.19, 95% CI: 1.10-4.37; p = 0.026), during a median follow-up of 2.9 years. This result was consistent among different CKD severities. In patients with CKD, functional ischemia in coronary artery stenosis was associated with poor clinical outcomes despite coronary revascularization.

Outcome of emergency surgery for acute type A aortic dissection in octogenarians.

BACKGROUND: Emergency surgery for acute type A aortic dissection (AAAD) was usually avoided or denied in octogenarians because of high surgical mortality. Refined surgical techniques and improved postoperative care have led to an improved in-hospital outcome. However, a significant number of operative survivors suffered from postoperative complications and had compromised quality of life. We sought to assess the clinical outcome of emergency surgery using a standard conservative approach in octogenarians with AAAD. METHODS: From 2004 to 2021, 123 patients underwent emergency surgery for AAAD by one surgeon using a standard conservative approach with right subclavian artery cannulation, no aortic cross-clamp, selective antegrade cerebral perfusion, moderate systemic hypothermia, reinforced sandwich technique, and a strategy of limited aortic resection. Hospital and late outcomes were assessed in patients with age >80 years. RESULTS: Eighteen patients (15%) were octogenarians with seven males (39%) and median age of 82 years (range, 80-89). Hypertension was present in six patients (33%). None had diabetes mellitus, Marfan, or bicuspid aortic valve. Dissection was intramural hematoma in six (33%) and DeBakey type I in 15 patients (83%). Cardiac tamponade with shock was present in seven patients (39%). Ascending aortic grafting was performed in 17 patients, and additional hemiarch replacement in one patient. The hospital mortality rate was 17% (3/18). Fourteen patients (82%) were alive and well at discharge. CONCLUSIONS: Emergency surgery for AAAD using a standard conservative approach showed an improved outcome in octogenarians. The majority of patients could return home with an acceptable living.

Transient Bacteremia Promotes Catheter-Related Central Venous Thrombosis through Neutrophil Extracellular Traps.

Formation of intravenous catheter-related thrombosis leads to central venous stenosis in patients requiring renal replacement therapy or chemotherapy infusion, yet the triggers or mechanisms remain unclear, especially in patients without symptoms of infection. In this study, we found that neutrophil extracellular traps (NETs) could be detected in the fibrin sheaths from dialysis patients without clinical manifestations of infection. Confocal microscopy revealed bacteria imbedded in NETs in the fibrin sheaths. Thirty-nine of 50 (78%) fibrin sheath specimens contained bacteria detectable by 16S ribosomal RNA genome typing with a predominance of Staphylococcus aureus (69%). In rat models, transient bacteremia of S. aureus induced NETs in enlarged fibrin sheaths, and treatment with DNase I alone significantly reduced both NET and fibrin sheath formation surrounding the catheter. Therefore, transient bacteremia could be a silent trigger that induces NET-related immunothrombosis enhancing catheter-related central venous stenosis.

Staged surgery for advanced cardiac intimal sarcoma involving the right atrium and the inferior vena cava.

Intimal sarcomas simultaneously involving the right atrium and the inferior vena cava (IVC) are rare. We report an advanced cardiac intimal sarcoma in the right atrium of a 19-year-old man that was complicated by tumor-related IVC thrombosis. We initially performed partial tumor resection and vena cava thrombectomy to resolve the circulatory obstruction, because complete resection was difficult due to the invading malignancy and an unclear margin. The patient received adjuvant chemo- and radiotherapy along with anticoagulant therapy. After 3 months, the border of the residual sarcoma was clear, and the patient underwent a secondary complete sarcoma excision (including that of the right atrium) and a suprahepatic vena cava reconstruction. At the 2-year follow-up, there was no tumor recurrence. We conclude that aggressive treatment and a staged complete resection can lead to improved outcomes for advanced cardiac intimal sarcoma with poor prognosis.

Identification of potential therapeutic antimicrobial peptides against Acinetobacter baumannii in a mouse model of pneumonia.

Acinetobacter baumannii-induced nosocomial pneumonia has become a serious clinical problem because of high antibiotic resistance rates. Antimicrobial peptides (AMP) are an ideal alternative strategy due to their broad-spectrum of antimicrobial activity and low incidence of bacterial resistance. However, their application is limited by toxicity and stability in vivo. The present study used a mouse model to directly identify potential AMPs effective for treatment of A. baumannii-induced pneumonia. Fifty-eight AMPs were screened and two identified (SMAP-29 and TP4) to have prophylactic effects which prevented the death of mice with pneumonia. Furthermore, two TP4 derivatives (dN4 and dC4) were found to have therapeutic activity in pneumonia mouse models by peritoneal or intravenous administration. Both dN4 and dC4 also inhibited and/or eliminated A. baumannii biofilms at higher doses. Taken together, these data suggest the AMP derivatives dN4 and dC4 represent a potential treatment strategy for A. baumannii-induced pneumonia.

PspC domain-containing protein (PCP) determines Streptococcus mutans biofilm formation through bacterial extracellular DNA release and platelet adhesion in experimental endocarditis.

Bacterial extracellular DNA (eDNA) and activated platelets have been found to contribute to biofilm formation by Streptococcus mutans on injured heart valves to induce infective endocarditis (IE), yet the bacterial component directly responsible for biofilm formation or platelet adhesion remains unclear. Using in vivo survival assays coupled with microarray analysis, the present study identified a LiaR-regulated PspC domain-containing protein (PCP) in S. mutans that mediates bacterial biofilm formation in vivo. Reverse transcriptase- and chromatin immunoprecipitation-polymerase chain reaction assays confirmed the regulation of pcp by LiaR, while PCP is well-preserved among streptococcal pathogens. Deficiency of pcp reduced in vitro and in vivo biofilm formation and released the eDNA inside bacteria floe along with reduced bacterial platelet adhesion capacity in a fibrinogen-dependent manner. Therefore, LiaR-regulated PCP alone could determine release of bacterial eDNA and binding to platelets, thus contributing to biofilm formation in S. mutans-induced IE.