Design and Behavior of Lightweight Flexible Structure with Spatial Pattern Reducing Contact Surface Fraction.

Flexible structures are increasingly important in biomedical applications, where they can be used to achieve adaptable designs. This paper presents a study of the design and behavior of 3D-printed lightweight flexible structures. In this work, we focus on the design principles and numerical modelling of spatial patterns, as well as their mechanical properties and behavior under various loads. Contact surface fraction was determined as the ratio of the surface area of the printed pattern to the surface area of the entire curved surface. The objective of this work is to design a spatial pattern reducing contact surface fraction and develop a non-linear numerical model evaluating the structure's stiffness; in addition, we aimed to identify the best design pattern with respect to its stiffness:mass ratio. The experimental verification of the numerical model is performed on 3D-printed prototypes prepared using the Selective Laser Sintering (SLS) method and made of Nylon-Polyamide 12. The obtained results provide insights into designing and optimizing lightweight external biomedical applications such as prostheses, orthoses, helmets, or adaptive cushions.

A novel labeling modality of intra-abdominal lesions with Magseed magnetic marker and extirpation by Sentimag probe navigation.

OBJECTIVE: This study aimed to evaluate our experience with the use of Magseed, the magnetic metallic marker, as a localization technique followed by Sentimag probe detection in patients with solitary intra-abdominal local metastases with subsequent resection of the lesions. METHODS: Five patients underwent resection after the lesion was marked with the Magseed magnetic marker. Prior to the surgery, a computed tomography scan of the chest and abdomen and/or positron emission tomography was performed to rule out the dissemination of the disease. The indication for surgery was evaluated in a meeting of a multidisciplinary team, and the placement of the magnetic marker under computed tomography control had been performed the day before the planned procedure. RESULTS: The present preliminary outcomes have revealed that Magseed might be a promising technique that is feasible and safe, particularly when the postsurgical anatomic conditions in the abdominal cavity are altered and the lesions are not visible or palpable. Surgical extirpation of lesions occurred without complications in each case. In all the cases, the resection was complete and curative, and one wound infection in all (20%), without any major complications, had occurred. The mean hospital stay was 6.6 days. CONCLUSION: Magseed utilization, as a localization technique, followed by Sentimag probe detection in intra-abdominal tumors has not been reported before. Improving the visualization and, consequently, the precise marking of the lesion with subsequent radical removal can prevent insufficient or excessive removal of healthy tissue, leading to a faster diagnosis and better overall clinical outcomes.

Evaluation of breast stiffness pathology based on breast compression during mammography: Proposal for novel breast stiffness scale classification.

Breast cancer is diagnosed through a patient's Breast Self-Examination (BSE), Clinical Breast Examination (CBE), or para-clinical methods. False negativity of PCM in breast cancer diagnostics leads to a persisting problem associated with breast tumors diagnosed only in advanced stages. As the tumor volume/size at which it becomes invasive is not clear, BSE and CBE play an exceedingly important role in the early diagnosis of breast cancer. The quality and effectiveness of BSE and CBE depend on several factors, among which breast stiffness is the most important one. In this study, the authors present four methods for evaluating breast stiffness pathology during mammography examination based on the outputs obtained during the breast compression process, id est, without exposing the patient to X-Ray radiation. Based on the subjective assessment of breast stiffness by experienced medical examiners, a novel breast stiffness classification was designed, and the best method of its objective measurement was calibrated to fit the scale. Hence, this study provides an objective tool for the identification of patients who, being unable to perform valid BSE, could benefit from an increased frequency of mammography screening. Dum vivimus servimus.

Radiation-associated angiosarcoma of the breast: An international multicenter analysis.

INTRODUCTION: Radiation-associated angiosarcoma (RAAS) is a rare and serious complication of breast irradiation. Due to the rarity of the condition, clinical experience is limited and publications on this topic include only retrospective studies or case reports. MATERIALS AND METHODS: All patients diagnosed with RAAS between January 2000 and December 2017 in twelve centers across the Czech Republic and Slovakia were evaluated. RESULTS: Data of 53 patients were analyzed. The median age at diagnosis was 72 (range 44-89) years. The median latency period between irradiation and diagnosis of RAAS was 78 (range 36-172) months. The median radiation dose was 57.6 (range 34-66) Gy. The whole breast radiation therapy with radiation boost to the tumor bed was the most common radiotherapy regimen. Total mastectomy due to RAAS was performed in 43 patients (81%), radical excision in 8 (15%); 2 patients were not surgically treated due to unresectable disease. Adjuvant chemotherapy followed surgical therapy of RAAS in 18 patients, 3 patients underwent adjuvant radiotherapy. The local recurrence rate of RAAS was 43% and the median time from surgery to the onset of recurrence was 7.5 months (range 3-66 months). The 3-year survival rate was 56%, the 5-year survival rate was only 33%. 46% of patients died during the follow-up period. CONCLUSION: The present data demonstrate that RAAS is a rare condition with high local recurrence rate (43%) and mortality (the 5-year survival rate was 33%.). Early diagnosis of RAAS based on biopsy is crucial for treatment with radical intent. Surgery with negative margins constitutes the most important part of the therapy; the role of adjuvant chemotherapy and radiotherapy is still unclear.

Modeling and Testing of Flexible Structures with Selected Planar Patterns Used in Biomedical Applications.

Flexible structures (FS) are thin shells with a pattern of holes. The stiffness of the structure in the normal direction is reduced by the shape of gaps rather than by the choice of the material based on mechanical properties such as Young's modulus. This paper presents virtual prototyping of 3D printed flexible structures with selected planar patterns using laboratory testing and computer modeling. The objective of this work is to develop a non-linear computational model evaluating the structure's stiffness and its experimental verification; in addition, we aimed to identify the best of the proposed patterns with respect to its stiffness: load-bearing capacity ratio. Following validation, the validated computational model is used for a parametric study of selected patterns. Nylon-Polyamide 12-was chosen for the purposes of this study as an appropriate flexible material suitable for 3D printing. At the end of the work, a computational model of the selected structure with modeling of load-bearing capacity is presented. The obtained results can be used in the design of external biomedical applications such as orthoses, prostheses, cranial remoulding helmets padding, or a new type of adaptive cushions. This paper is an extension of the conference paper: "Modeling and Testing of 3D Printed Flexible Structures with Three-pointed Star Pattern Used in Biomedical Applications" by authors Repa et al.

Effect of bilberry extract (Vaccinium myrtillus L.) on drug-metabolizing enzymes in rats.

Vaccinium myrtillus L. (bilberry) fruit is a blue-colored berry with a high content of anthocyanins. These bioactive secondary metabolites are considered to play a major role in the health-promoting properties of bilberries. Our in vivo study was designed to assess the possible influence of bilberry extract on drug-metabolizing enzymes (DMEs). Rats were exposed to bilberry extract in drinking water at two concentrations (0.15 and 1.5 g/L). Selected DMEs were determined (mRNA expression and enzymatic activity) after 29 and 58 days in rat liver. In addition, a panel of antioxidant, physiological, biochemical and hematological parameters was studied; these parameters did not demonstrate any impact of bilberry extract on the health status of rats. A significant increase in activity was observed in cytochrome P450 (CYP) 2C11 (131% of control) and CYP2E1 (122% of control) after a 29-day administration, while the consumption of a higher concentration for a longer time led to a mild activity decrease. Slight changes were observed in some other DMEs, but they remained insignificant from a physiological perspective. According to our results, we conclude that the consumption of bilberries as a food supplement should not pose a risk of interacting with co-administered drugs based on their metabolism.

In vivo evaluation of effect of anthocyanin-rich wheat on rat liver microsomal drug-metabolizing cytochromes P450 and on biochemical and antioxidant parameters in rats.

Wheat is one of the most important agricultural crops worldwide. Recently, anthocyanin-rich wheat genotypes were introduced to the market as a food with added value. In the experiment described here, two different genotypes with blue grain were studied (UC66049 and Skorpion). The aim of the investigation was to determine whether a 72-day-long intake of anthocyanin-rich wheat can influence the drug-metabolizing microsomal cytochromes P450 (using standard drug substrates of rat/human liver microsomal cytochromes P450) and antioxidant status, which indicated the ability of the rats' liver to metabolize drugs or xenobiotics. Consumption of an anthocyanin-rich diet moderately increased the activity and mRNA expression of the studied CYPs by 20-55% relative to the control (with the exception of CYP2B1/2). The health status of rats was good; the weight gain was lower in the group with anthocyanin-rich UC66049 grain compared to the other two groups (control and Skorpion-fed one). The antioxidant power of plasma was mildly but significantly higher in the test groups, other antioxidant parameters remained unaffected, except for an increased level of total SH groups. Based on our observations, there will most likely be no significant influence of the consumption of anthocyanin-rich wheat on the metabolism of xenobiotics and drugs.

Functional outcome of low rectal resection evaluated by anorectal manometry.

BACKGROUND: Low anterior resection syndrome (LARS) covers disordered bowel function after rectal resection, leading to deterioration in patients' quality of life. The aim of this study was to evaluate anorectal function after laparoscopic low anterior resection (LAR) by means of standardized instruments. METHODS: This was a prospective clinical cohort study conducted in a single institution to assess functional outcome of patients 1 year after laparoscopic LAR by means of LARS score and high-resolution anorectal manometry. RESULTS: In total, 65 patients were enrolled in the study. Mean tumour height was 9.4 ± 1.8 cm; total mesorectal excision during laparoscopic LAR with low end-to-end colorectal anastomosis was performed in all patients. One year after the surgery, minor LARS was detected in 33.9% of patients, major LARS in 36.9% of patients. Anorectal manometry revealed decreased resting pressure and normal squeeze pressure of the anal sphincters in the majority of our patients. Rectal compliance and rectal volume tolerability (first sensation, urge to defaecate and discomfort volume) were significantly reduced. The statistical testing of the correlation between LARS and manometry parameters showed that with increasing seriousness of LARS, values of some parameters (resting pressure, first sensation, urge to defaecate, discomfort volume and rectal compliance) were reduced. CONCLUSION: This study indicates that the majority of patients after laparoscopic LAR experience symptoms of minor or major LARS. These patients have decreased resting anal sphincter pressures, decreased rectal volume tolerability and decreased rectal compliance.

Resveratrol and its glycon piceid are stable polyphenols.

Plant extracts containing phytopolyphenols, including resveratrol, are extensively used as nutraceutical supplements. Recent reports allege their lack of stability at ambient conditions. We have studied the stability of resveratrol and its glycon piceid in a mixture with a whole grape extract for 2 years (long-term stability) under Good Manufacturing Practice pharmaceutical protocols (at 60% humidity and 25 degrees C). The neat compounds were followed for 4 years under conditions of "accelerated stability," at 75% humidity and 40 degrees C, all in the presence of ambient air. Chromatographic analysis did not detect any instability, thus disproving the claims to the opposite. No storage precautions are necessary for these nutritional supplements.