Lifetime-configurable soft robots via photodegradable silicone elastomer composites.

Developing soft robots that can control their own life cycle and degrade on-demand while maintaining hyperelasticity is a notable research challenge. On-demand degradable soft robots, which conserve their original functionality during operation and rapidly degrade under specific external stimulation, present the opportunity to self-direct the disappearance of temporary robots. This study proposes soft robots and materials that exhibit excellent mechanical stretchability and can degrade under ultraviolet light by mixing a fluoride-generating diphenyliodonium hexafluorophosphate with a silicone resin. Spectroscopic analysis revealed the mechanism of Si─O─Si backbone cleavage using fluoride ion (F-) and thermal analysis indicated accelerated decomposition at elevated temperatures. In addition, we demonstrated a robotics application by fabricating electronics integrated gaiting robot and a fully closed-loop trigger disintegration robot for autonomous, application-oriented functionalities. This study provides a simple yet novel strategy for designing life cycle mimicking soft robotics that can be applied to reduce soft robotics waste, explore hazardous areas, and ensure hardware security with on-demand destructive material platforms.

Factors affecting colonoscope insertion time in patients with or without a colostomy after left-sided colorectal resection.

BACKGROUND/AIMS: We examined whether the insertion time for colonoscopies performed after left-sided resection was different in patients with a colostomy from that in patients without a colostomy and identified factors that could impact colonoscopy performance. METHODS: We included consecutive patients who underwent colonoscopy between July 2005 and March 2011 after left-sided colorectal resection for colorectal cancer. We classified surgical methods according to the presence or absence of a colostomy and evaluated colonoscope insertion time retrospectively. Furthermore, we analyzed factors that might affect insertion time. RESULTS: A total of 1,041 patients underwent colonoscopy after left-sided colorectal resection during the study period. The colonoscopy completion rate was 98.6 %, and the mean insertion time was 6.1 ± 4.6 min (median 4.7 min, range 0.3-35.8 min). A shorter resection length of colon, the presence of a colostomy, and a lower endoscopist case volume were found to be independent factors associated with prolonged insertion time in patients with left-sided colorectal resection. Among experienced colonoscopists, no colonoscopy-associated or clinical factors were found to affect insertion time. However, a shorter resection length of colon, the presence of a colostomy, and poor bowel preparation were associated with prolonged insertion time among inexperienced endoscopists. CONCLUSIONS: We identified three factors that affect colonoscope insertion time after left-sided colorectal resection, including the presence of a colostomy. Inexperienced endoscopists were much more affected by the presence of a colostomy after left-sided colorectal resection. These findings have implications for the practice and teaching of colonoscopy after left-sided colorectal resection.

A comparison of logistic regression analysis and an artificial neural network using the BI-RADS lexicon for ultrasonography in conjunction with introbserver variability.

To determine which Breast Imaging Reporting and Data System (BI-RADS) descriptors for ultrasound are predictors for breast cancer using logistic regression (LR) analysis in conjunction with interobserver variability between breast radiologists, and to compare the performance of artificial neural network (ANN) and LR models in differentiation of benign and malignant breast masses. Five breast radiologists retrospectively reviewed 140 breast masses and described each lesion using BI-RADS lexicon and categorized final assessments. Interobserver agreements between the observers were measured by kappa statistics. The radiologists' responses for BI-RADS were pooled. The data were divided randomly into train (n = 70) and test sets (n = 70). Using train set, optimal independent variables were determined by using LR analysis with forward stepwise selection. The LR and ANN models were constructed with the optimal independent variables and the biopsy results as dependent variable. Performances of the models and radiologists were evaluated on the test set using receiver-operating characteristic (ROC) analysis. Among BI-RADS descriptors, margin and boundary were determined as the predictors according to stepwise LR showing moderate interobserver agreement. Area under the ROC curves (AUC) for both of LR and ANN were 0.87 (95% CI, 0.77-0.94). AUCs for the five radiologists ranged 0.79-0.91. There was no significant difference in AUC values among the LR, ANN, and radiologists (p > 0.05). Margin and boundary were found as statistically significant predictors with good interobserver agreement. Use of the LR and ANN showed similar performance to that of the radiologists for differentiation of benign and malignant breast masses.

Incidence and mortality of hip fracture among the elderly population in South Korea: a population-based study using the national health insurance claims data.

BACKGROUND: The lack of epidemiologic information on osteoporotic hip fractures hampers the development of preventive or curative measures against osteoporosis in South Korea. We conducted a population-based study to estimate the annual incidence of hip fractures. Also, we examined factors associated with post-fracture mortality among Korean elderly to evaluate the impact of osteoporosis on our society and to identify high-risk populations. METHODS: The Korean National Health Insurance (NHI) claims database was used to identify the incidence of hip fractures, defined as patients having a claim record with a diagnosis of hip fracture and a hip fracture-related operation during 2003. The 6-month period prior to 2003 was set as a 'window period,' such that patients were defined as incident cases only if their first record of fracture was observed after the window period. Cox's proportional hazards model was used to investigate the relationship between survival time and baseline patient and provider characteristics available from the NHI data. RESULTS: The age-standardized annual incidence rate of hip fractures requiring operation over 50 years of age was 146.38 per 100,000 women and 61.72 per 100,000 men, yielding a female to male ratio of 2.37. The 1-year mortality was 16.55%, which is 2.85 times higher than the mortality rate for the general population (5.8%) in this age group. The risk of post-fracture mortality at one year is significantly higher for males and for persons having lower socioeconomic status, living in places other than the capital city, not taking anti-osteoporosis pharmacologic therapy following fracture, or receiving fracture-associated operations from more advanced hospitals such as general or tertiary hospitals. CONCLUSION: This national epidemiological study will help raise awareness of osteoporotic hip fractures among the elderly population and hopefully motivate public health policy makers to develop effective national prevention strategies against osteoporosis to prevent hip fractures.

Rates of change to a positive result in subsequent screening mammography in Korean women: a retrospective observational study.

OBJECTIVES: This retrospective cohort study aimed at calculating some parameters of changes in the findings of the subsequent screening mammography (SSM) in female Korean volunteers. METHODS: The study included screenees aged 30 to 79 years who underwent SSM voluntarily after testing negative in the baseline screenings performed between January 2007 and December 2011. A change to a positive result was defined as category 4 or 5 by using the American College of Radiology Breast Imaging Reporting and Data System. The proportion of results that had changed to positive (CP, %) was calculated by dividing the number of cases with results that were positive in the SSM by the total number of study participants. The rate of results that had changed to positive (CR, cases per 100 000 screenee-months) was calculated by dividing the number of cases with results that were positive in the SSM by the total number of months of the follow-up period. RESULTS: The overall CP and CR in all age groups (n=77 908) were 2.26% and 93.94 cases per 100 000 screenee-months, respectively. The median CP interval in the subjects who had positive SSM results was 30 to 36 months, while that in the age group of 30 to 39 years was shorter. CONCLUSIONS: Different screening intervals should be considered among women aged between 30 and 59 years. In addition, a strategy for a screening program should be developed for the age group of 30 to 39 years, in particular.

Distribution of dense breasts using screening mammography in Korean women: a retrospective observational study.

OBJECTIVES: This retrospective observational study evaluated the distribution of dense breasts by age group among healthy Korean women. METHODS: Participants were women aged 30 years and older who voluntarily underwent screening mammography between January 2007 and December 2011. Women who received the Breast Imaging Reporting and Data System for mammographic density of 3 or 4 were defined as having dense breasts. The proportion of women with dense breasts (PDB, %) was calculated by dividing the number of participants with dense breasts by the total number of participants. RESULTS: Among the 231,058 women who participated, 78.15% were classified as having dense breasts. PDB was highest in the youngest age group (PDB=94.87%) and lowest in the oldest age group. The greatest difference in PDB between adjacent age groups was observed in the group aged 60-64 years. CONCLUSIONS: The results show that the proportion of dense breasts by age group increased in all age groups, except in those aged 35-39 years. These findings suggest an association between the age distribution of dense breasts and trends in breast cancer incidence. Further studies are needed to estimate the change in breast cancer incidence rate by age and the accumulation of fatty breast tissue in Korean women.

Prediction of Colorectal Cancer Risk Using a Genetic Risk Score: The Korean Cancer Prevention Study-II (KCPS-II).

Colorectal cancer (CRC) is among the leading causes of cancer deaths and can be caused by environmental factors as well as genetic factors. Therefore, we developed a prediction model of CRC using genetic risk scores (GRS) and evaluated the effects of conventional risk factors, including family history of CRC, in combination with GRS on the risk of CRC in Koreans. This study included 187 cases (men, 133; women, 54) and 976 controls (men, 554; women, 422). GRS were calculated with most significantly associated single-nucleotide polymorphism with CRC through a genomewide association study. The area under the curve (AUC) increased by 0.5% to 5.2% when either counted or weighted GRS was added to a prediction model consisting of age alone (AUC 0.687 for men, 0.598 for women) or age and family history of CRC (AUC 0.692 for men, 0.603 for women) for both men and women. Furthermore, the risk of CRC significantly increased for individuals with a family history of CRC in the highest quartile of GRS when compared to subjects without a family history of CRC in the lowest quartile of GRS (counted GRS odds ratio [OR], 47.9; 95% confidence interval [CI], 4.9 to 471.8 for men; OR, 22.3; 95% CI, 1.4 to 344.2 for women) (weighted GRS OR, 35.9; 95% CI, 5.9 to 218.2 for men; OR, 18.1, 95% CI, 3.7 to 88.1 for women). Our findings suggest that in Koreans, especially in Korean men, GRS improve the prediction of CRC when considered in conjunction with age and family history of CRC.