Compressive Behavior and Mechanical Characteristics and Their Application to Stress-Strain Relationship of Steel Fiber-Reinforced Reactive Powder Concrete

Although mechanical properties of concrete under uniaxial compression are important to design concrete structure, current design codes or other empirical equations have clear limitation on the prediction of mechanical properties. Various types of fiber-reinforced reactive powder concrete matrix were tested for making more usable and accurate estimation equations for mechanical properties for ultra high strength concrete. Investigated matrix has compressive strength ranged from 30 MPa to 200 MPa. Ultra high strength concrete was made by means of reactive powder concrete. Preventing brittle failure of this type of matrix, steel fibers were used. The volume fraction of steel fiber ranged from 0 to 2%. From the test results, steel fibers significantly increase the ductility, strength and stiffness of ultra high strength matrix. They are quantified with previously conducted researches about material properties of concrete under uniaxial loading. Applicability of estimation equations for mechanical properties of concrete was evaluated with test results of this study. From the evaluation, regression analysis was carried out, and new estimation equations were proposed. And these proposed equations were applied into stress-strain relation which was developed by previous research. Ascending part, which was affected by proposed equations of this study directly, well fitted into experimental results

Trends in radiotherapy administration in the management of hepatocellular carcinoma: Analysis of a Korean tertiary hospital registry of hepatocellular carcinoma patients diagnosed between 2005 and 2017

PurposeTo present the trends in radiotherapy for the management of hepatocellular carcinoma (HCC) at a single tertiary referral hospital in South Korea.Materials and MethodsWe retrospectively reviewed prospectively collected registry data of patients newly diagnosed with HCC between January 2005 and December 2017 at the Samsung Medical Center. Trends in radiotherapy, delivery techniques, tumor stage, and age were evaluated.ResultsDuring the study period, 9,132 patients were newly diagnosed with HCC at our institution. Of these, 2,445 patients (26.8%) received radiotherapy for all lesions, including extrahepatic metastases; 1,865 patients (20.4%) received radiotherapy for intrahepatic lesions alone, and 469 patients (5.1%) received radiotherapy as initial management. Although the proportion of patients receiving radiotherapy increased slightly over the study period (24.2% vs. 26.6%), the proportions of patients receiving radiotherapy for intrahepatic lesions (16.8% vs. 21.9%) and as initial management (0.1% vs. 12.5%) increased dramatically. The majority of patients treated between 2005 and 2008 received three-dimensional conformal radiotherapy (56.3%), whereas the majority of patients treated between 2018 and 2021 received proton beam therapy (43.6%). With the technical developments, the overall survival (OS) of patients who received radiotherapy as initial management increased significantly (5-year OS: from 5.4% to 30.1%), and the OS difference between patients who did and did not receive radiotherapy as initial management significantly decreased (ratio of restricted mean survival time: from 0.383 to 0.544).ConclusionThis registry-based, retrospective study indicated an increasing trend in the utilization of radiotherapy, adoption of advanced radiotherapy techniques, and OS improvements in patients with HCC

Differences in complications and asymmetry in patients who did not receive a balancing procedure in two-stage and direct-to-implant breast reconstruction

Background Implant-based immediate breast reconstruction surgery with nipple-sparing mastectomy has recently been favored by patients. However, in patients who do not wish to undergo balancing procedures, it is difficult to select the appropriate implant size, making it challenging to achieve a symmetrical breast shape. Therefore, this study investigated the differences in breast asymmetry and other complications in patients who underwent a two-stage procedure or direct-to-implant (DTI) breast reconstruction to determine whether the two-stage procedure can produce more favorable outcomes. Methods The participants of this study were patients who underwent immediate two-stage breast reconstruction or DTI breast reconstruction from May 2018 to April 2022, did not receive postoperative radiotherapy, and did not wish to undergo any balancing procedures. An acellular dermal matrix was used for breast reconstruction in all patients, and a single reconstructive surgeon performed all the operations. Statistical significance was set at P<0.05. Results No significant differences in complications were found between the patients who underwent DTI breast reconstruction and those who underwent two-stage breast reconstruction. In the two-stage breast reconstruction group, breast volume asymmetry was observed in 18.4% (seven patients), which was significantly lower than the percentage of 44.7% (17 patients) observed in the DTI group. Conclusions Breast asymmetry was observed in a significant proportion of the patients in both groups. However, because breast volume asymmetry was more common in the DTI group than in the two-stage breast reconstruction group, two-stage breast reconstruction may be a favorable method for patients who do not wish to undergo balancing procedures

Health behaviors, periodontal conditions, and periodontal pathogens in spontaneous preterm birth: A case-control study in Korea

Background: This study aims to determine whether periodontal conditions or dental health behaviors are risk factors for preterm birth (PTB), and whether periodontal pathogens are risk indicators for PTB among Korean mothers. Methods: This study was designed as a hospital-based case-control study. Examiner masking was ensured for the validity of the examinations. The mothers included those who gave birth between November 2007 and July 2009 at the obstetrics clinic of a general hospital in Seoul, Korea. Information on demographic and health conditions, periodontal conditions, and microbacterial data was collected. Results: A total of 172 women met the inclusion criteria, 59 mothers who delivered a preterm neonate were assigned to the case group while the other 113 were assigned to the control group. There were no significant differencesin demographic information, oral health conditions, and obstetric characteristics. Among health-related behaviors, only scaling within 12 months before pregnancy showed a significant difference (P = 0.031). Even in the adjusted logistic model, only the difference in the experience of scaling before pregnancy was significant between the PTB cases and the controls (P = 0.039). Periodontal disease did not exhibit a significant relationship with PTB even after adjustment for potential confounding factors. Among the microbacterial factors, only Porphyromonas gingivalis showed a slight difference (P = 0.060). Conclusion: There was a significant difference inscaling experience within 12 months before pregnancy and P. gingivalis showed a marginal difference between the PTB and the control groups but clinical periodontal conditions showed no association with PTB.This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD, Basic Research Promotion Fund, Seoul, Korea; E00230)

Successful Treatment of Stereotactic Body Radiation Therapy Combined with Transarterial Chemolipiodolization for Hepatocellular Carcinoma with Biliary Obstruction

Conventional radiation therapy (RT) is a widely recognized treatment for hepatocellular carcinoma (HCC). However, conventional RT plays only a limited role in HCC treatment because of its low efficacy and the low tolerance of the liver for this modality. Stereotactic body radiation therapy (SBRT) was recently developed and represents the most advanced radiation therapy technique currently available. It can deliver a high dose in a short time to well-defined hepatic tumors, with rapid dose fall-off gradients. We believe that SBRT with transarterial chemolipiodolization (TACL) may prove promising as a combined treatment modality for HCC due to its precision and relative safety. Here we present a case of successful treatment of advanced HCC with obstructive jaundice using this combined modality

Volumetric change of the latissimus dorsi muscle after immediate breast reconstruction with an extended latissimus dorsi musculocutaneous flap

Background In immediate breast reconstruction using an extended latissimus dorsi musculocutaneous (eLDMC) flap, the volume of the flap decreases, which causes a secondary deformity of the breast shape. Since little research has investigated this decrease in muscle volume, the authors conducted an objective study to characterize the decrease in muscle volume after breast reconstruction using an eLDMC flap. Methods Research was conducted from October 2011 to November 2016. The subjects included 23 patients who underwent mastectomy due to breast cancer, received immediate reconstruction using an eLDMC flap without any adjuvant chemotherapy or radiotherapy, and received a computed tomography (CT) scan from days 7 to 10 after surgery and 6 to 8 months postoperatively. In 10 patients, an additional CT scan was conducted 18 months postoperatively. Axial CT scans were utilized to measure the volumetric change of the latissimus dorsi muscle during the follow-up period. Results In the 23 patients, an average decrease of 54.5% was observed in the latissimus dorsi muscle volume between the images obtained immediately postoperatively and the scans obtained 6 to 8 months after surgery. Ten patients showed an average additional decrease of 11.9% from 6–8 months to 18 months after surgery. Conclusions We studied changes in the volume of the latissimus dorsi muscle after surgery using an eLDMC flap performed after a mastectomy without adjuvant chemotherapy or radiotherapy. In this study, we found that immediate breast reconstruction using a latissimus dorsi muscle flap led to a decrease in muscle volume of up to 50%

The Role of Laryngopharyngeal Reflux as a Risk Factor in Laryngeal Cancer: A Preliminary Report

Objectives. To evaluate the significance of laryngopharyngeal reflux (LPR) as a risk factor in laryngeal cancer.Methods. We performed a case-control study with 29 consecutive laryngeal cancer patients who had undergone 24-hour ambulatory double pH monitoring from 2003 to 2006. The control group included 300 patients who had undergone 24-hour ambulatory double pH monitoring due to LPR-related symptoms. We analyzed the prevalence of LPR and numerous parameters from the 24-hour ambulatory double pH monitoring in the laryngeal cancer patient and control groups. Pathologic LPR is defined when more than three episodes of LPR occur in 24 hours.Results. The prevalence of pathologic LPR was significantly higher in the laryngeal cancer group than the control group (P=0.049). The reflux number of the upper probe was significantly higher in the laryngeal cancer group (P&lt;0.001). However the effects of pathologic LPR on laryngeal cancer risk were diluted after adjusting for smoking and alcohol consumption in the multivariable logistic regression.Conclusion. The pathologic LPR might be a possible risk factor in the development of laryngeal cancer. A further study should be necessary to verify the exact role of LPR in laryngeal cancer