A review of recent advances of piezoelectric poly-L-lactic acid for biomedical applications.

Poly-L-lactic acid (PLLA), recognized as a piezoelectric material, not only demonstrates exceptional piezoelectric properties but also exhibits commendable biocompatibility and biodegradability. These properties render PLLA highly promising for diverse applications, including sensors, wearable devices, biomedical engineering, and related domains. This review offers a comprehensive overview of the distinctive piezoelectric effect of PLLA-based material and delves into the latest advancements in its preparation strategies as a piezoelectric material. It further presents recent research progress in PLLA-based piezoelectric materials, particularly in the realms of health monitoring, skin repair, nerve regeneration, and tissue repair. The discourse extends to providing insights into potential future trajectories for the development of PLLA-based piezoelectric materials.

Treatment of thoracolumbar fracture with pedicle screws at injury level: a biomechanical study based on three-dimensional finite element analysis.

The aim of this study was to investigate the biomechanical mechanisms of treatment of thoracolumbar compression fracture with pedicle screws at injury level based on a three-dimensional finite element method. We constructed one three-dimensional finite element model of T11-L1 in a patient with a compression fracture of the T12 vertebral body(anterior edges of vertebral body were compressed to 1/2, and kyphosis Cobb angle was 18.6°) fixed by four pedicle screws and another model fixed by six pedicle screws at the injured vertebrae, and then assigned different forces to the two models to account for axial compression, flexion, extension, left lateral bending, and rightward axial rotation by Ansys software. After different loading forces were applied to the models, we recorded stress measurements on the vertebral pedicle screws, as well as the maximum displacement of T11. The stress distribution suggested that stress concentration was appreciable at the root of the pedicle screws under different loading modalities. Under axial compression, flexion, extension, left lateral bending, and rightward axial rotation load, the stress for the superior screw was significantly greater than the stress for the inferior screw (P < 0.05). The stress in the six pedicle screw fixation model was significantly decreased compared to the four screw interbody fusion model (P < 0.05), but the maximum displacement of T11 between two models under different loadings was not statistically different. The use of pedicle screws at injured vertebral bodies may optimize internal fixation load and reduce the incidence of broken screws.

Spatially varying relationships of soil Se concentration and rice Se concentration in Guangxi, China: A geographically weighted regression approach.

In recent years, the biogeochemical behavior and environmental impact of Selenium (Se) on soil-plant systems have received widespread attention, and traditional statistical methods reveal generally positive correlations between rice Se and soil Se. However, that initial positive relationship may have been obscured by local external factors. Using local scale data from the geochemical evaluation of land quality project, this work employed geographically weighted regression (GWR) to examine the spatial variation of rice Se (as the dependent variable) and soil Se (as the independent variable) in Guangxi. Strong and weak correlation coefficients occur between rice Se and soil Se, thereby indicating that their relationships are spatially varying. Guangxi is characterized by significantly positive correlations in most areas, with weak correlations mostly found in the south-western and central-eastern regions. Areas with weak correlation can be divided into two patterns: high soil Se with low rice Se and high rice Se with low soil Se. The unique patterns are correlated with distinct natural factors, particularly the abundance of Fe-rich soils in the carbonate area; by contrast, sandstone areas in central Guangxi may have been affected by anthropogenic activities. To reveal the spatially varying relationships at the local scale, we employed GWR, an effective tool that allowed us to identify the association between environmental variables and influencing factors and explore spatially varying relationships between them. This study breaks through the existing understanding that soil Se is completely positively correlated with rice Se for the first time, and concludes that their correlation is spatially variable, providing an effective approach for the study of complex relationships.

Dynamic deformation behavior of a face-centered cubic FeCoNiCrMn high-entropy alloy.

In this study, mechanical tests were conducted on a face-centered cubic FeCoNiCrMn high-entropy alloy, both in tension and compression, in a wide range of strain rates (10-4-104 s-1) to systematically investigate its dynamic response and underlying deformation mechanism. Materials with different grain sizes were tested to understand the effect of grain size, thus grain boundary volume, on the mechanical properties. Microstructures of various samples both before and after deformation were examined using electron backscatter diffraction and transmission electron microscopy. The dislocation structure as well as deformation-induced twins were analyzed and correlated with the measured mechanical properties. Plastic stability during tension of the current high-entropy alloy (HEA), in particular, at dynamic strain rates, was discussed in lights of strain-rate sensitivity and work hardening rate. It was found that, under dynamic conditions, the strength and uniform ductility increased simultaneously as a result of the massive formation of deformation twins. Specifically, an ultimate tensile strength of 734 MPa and uniform elongation of ∼63% are obtained at 2.3 × 103 s-1, indicating that the alloy has great potential for energy absorption upon impact loading.

Overexpression of osteopontin is associated with more aggressive phenotypes in human non-small cell lung cancer.

PURPOSE: The extracellular matrix (ECM) molecule osteopontin is implicated in many pathologic processes, including inflammation, cell proliferation, ECM invasion, tumor progression, and metastasis. The present study evaluated the clinical and biological importance of osteopontin in human lung cancer. EXPERIMENTAL DESIGN AND RESULTS: Tissue microarrays derived from non-small cell lung cancer (NSCLC) patients were analyzed immunohistochemically. Osteopontin protein expression was observed in 64.5% (205 of 318) of primary tumors and 75.5% (108 of 143) of lymph node metastases, but in only 27.9% (12 of 43) of normal-appearing bronchial epithelial and pulmonary tissues. Osteopontin expression was associated with tumor growth, tumor staging, and lymph node invasion. In vitro osteopontin enhanced ECM invasion of NSCLC cells, and an osteopontin antibody abolished this effect. We further analyzed osteopontin levels in circulating plasma derived from 158 patients with NSCLC, 54 patients of benign pulmonary disease, and 25 healthy donors, and found that the median osteopontin levels for the three groups were 319.1, 161.6, and 17.9 ng/mL, respectively. CONCLUSIONS: Overexpression of osteopontin is common in primary NSCLC and may be important in the development and progression of the cancer. Osteopontin levels in the plasma may serve as a biomarker for diagnosing or monitoring patients with NSCLC.

Identification of differentially expressed genes in human lung squamous cell carcinoma using suppression subtractive hybridization.

Lung cancer is one of the major causes of cancer-related deaths. Over the past decade, much has been known about the molecular changes associated with lung carcinogenesis; however, our understanding to lung tumorigenesis is still incomplete. To identify genes that are differentially expressed in squamous cell carcinoma (SCC) of the lung, we compared the expression profiles between primarily cultured SCC tumor cells and bronchial epithelial cells derived from morphologically normal bronchial epithelium of the same patient. Using suppression subtractive hybridization (SSH), two cDNA libraries containing up- and down-regulated genes in the tumor cells were constructed, named as LCTP and LCBP. The two libraries comprise 258 known genes and 133 unknown genes in total. The known up-regulated genes in the library LCTP represented a variety of functional groups; including metabolism-, cell adhesion and migration-, signal transduction-, and anti-apoptosis-related genes. Using semi-quantitative reverse transcription-polymerase chain reaction, seven genes chosen randomly from the LCTP were analyzed in the tumor tissue paired with its corresponding adjacent normal lung tissue derived from 16 cases of the SCC. Among them, the IQGAP1, RAP1GDS1, PAICS, MLF1, and MARK1 genes showed a consistent expression pattern with that of the SSH analysis. Identification and further characterization of these genes may allow a better understanding of lung carcinogenesis.

Experimental studies on ultralow frequency pulsed gradient magnetic field inducing apoptosis of cancer cell and inhibiting growth of cancer cell.

The morphology characteristics of cell apoptosis of the malignant tumour cells in magnetic field-treated mouse was observed for the first time. The apoptotic cancer cell contracted, became rounder and divorced from adjacent cells; the heterochromatin condensed and coagulated together along the inner side of the nuclear membrane; the endoplasmic reticulums (ER) expanded and fused with the cellular membrane; many apoptotic bodies which were packed by the cellular membrane appeared and were devoured by some lymphocytes and plasma. Apoptosis of cancer cells was detected by terminal deoxynucleotidyl transferase mediatedin situ nick end labeling (TUNEL). It was found that the number of apoptosis cancer cells of the sample treated by the magnetic field is more than that of the control sample. The growth of malignant tumour in mice was inhibited and the ability of immune cell to dissolve cancer cells was improved by ultralow frequency (ULF) pulsed gradient magnetic field; the nuclei DNA contents decreased, indicating that magnetic field can block DNA replication and inhibit mitosis of cancer cells. It was suggested that magnetic field could inhibit the metabolism of cancer cell, lower its malignancy, and restrain its rapid and heteromorphic growth. Since ULF pulsed gradient magnetic field can induce apoptosis of cancer cells and inhibit the growth of malignant tumour, it could be used as a new method to treat cancer.

A modified split Hopkinson torsional bar system for correlated study of τ-γ relations, shear localization and microstructural evolution.

The conventional split Hopkinson torsional bar (SHTB) system consists of two bars, which can successfully produce the data for the construction of dynamic torsional shear stress and strain relationships. However, the system cannot provide reliable information on the progression of the deformed micro-structure during the test. The reverberation of waves in the bars and the tested specimen can spoil the microstructural pattern formed during the effective loading. This paper briefly reviews a modified version of the SHTB system consisting of four bars that has been developed. This modified system can eliminate the reverberation of waves in the specimen and provide only a single rectangular torsional stress pulse, thus it can properly freeze the microstructure formed during the effective period of loading in the specimen. By using the advantage of the modified SHTB system, together with a new design of specimen, it is possible to perform a correlated study of the dynamic stress-strain response, shear localization and the evolution of the microstructure at a fixed view-field (position) on a given specimen during the sequence of the loading time. The principles, experimental set-up and procedure, calibration and some preliminary results of the correlated study are reported in this paper.

The cross-sectional and longitudinal association of the BODE index with quality of life in patients with chronic obstructive pulmonary disease.

BACKGROUND: The body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index was shown at predicting the risk of death, exacerbation and disease severity among patients with COPD, but few studies verified relationship between BODE index and health related quality of life (HRQoL) among Chinese COPD patients. The objective of this study was to evaluate the relationship between BODE index and HRQoL in cross-sectional and longitudinal association analyses. METHODS: A multi-center prospective cohort study was initially conducted in 491 stable COPD patients in Beijing, China. Health status (HRQoL) was assessed by St. George's Respiratory Questionnaire (SGRQ); the BODE index was calculated for each patient; dyspnea was assessed using the 5-grade Medical Research Council dyspnea scale. Other measurements included socio-demographic, body mass index (BMI), lung function test and 6-minute-walk test (6MWT). Patients were then followed monthly for 12 months. RESULTS: Only 450 patients completed the 1-year follow up and were enrolled in our present analyses. Mean age was (65.2 +/- 10.6) years, men 309 (68.7%). The BODE index was categorized into 4 subgroups: 0 - 2, 3 - 4, 5 - 6 and 7 - 10. At baseline BODE index was gradually increased with baseline total SGRQ and SGRQ subscales (P trend < 0.001). For individual components of BODE index, with the decrease of airflow limitation, and 6MWD, and with the increase of Medical Research Council (MRC) dyspnea grade, total SGRQ and SGRQ subscales were increased correspondingly, P trend < 0.05, respectively. Similar association patterns were found between baseline BODE index and its individual components and mean SGRQ scores at the end of 1-year follow up. By multiple linear regression analyses, baseline BODE index was not only significantly associated with SGRQ score at baseline but also with SGRQ score at the end of 1-year follow up after adjustment for age, male, current smoking, betas being 0.434 and 0.378, respectively. CONCLUSIONS: BODE index is associated with SGRQ score cross-sectionally and longitudinally among stable COPD patients. BODE index might have potential to be used as a sensitive tool to assess the status of quality of life and to monitor disease progression among stable COPD patients.

An approach to studying lung cancer-related proteins in human blood.

Early stage lung cancer detection is the first step toward successful clinical therapy and increased patient survival. Clinicians monitor cancer progression by profiling tumor cell proteins in the blood plasma of afflicted patients. Blood plasma, however, is a difficult cancer protein assessment medium because it is rich in albumins and heterogeneous protein species. We report herein a method to detect the proteins released into the circulatory system by tumor cells. Initially we analyzed the protein components in the conditioned medium (CM) of lung cancer primary cell or organ cultures and in the adjacent normal bronchus using one-dimensional PAGE and nano-ESI-MS/MS. We identified 299 proteins involved in key cellular process such as cell growth, organogenesis, and signal transduction. We selected 13 interesting proteins from this list and analyzed them in 628 blood plasma samples using ELISA. We detected 11 of these 13 proteins in the plasma of lung cancer patients and non-patient controls. Our results showed that plasma matrix metalloproteinase 1 levels were elevated significantly in late stage lung cancer patients and that the plasma levels of 14-3-3 sigma, beta, and eta in the lung cancer patients were significantly lower than those in the control subjects. To our knowledge, this is the first time that fascin, ezrin, CD98, annexin A4, 14-3-3 sigma, 14-3-3 beta, and 14-3-3 eta proteins have been detected in human plasma by ELISA. The preliminary results showed that a combination of CD98, fascin, polymeric immunoglobulin receptor/secretory component and 14-3-3 eta had a higher sensitivity and specificity than any single marker. In conclusion, we report a method to detect proteins released into blood by lung cancer. This pilot approach may lead to the identification of novel protein markers in blood and provide a new method of identifying tumor biomarker profiles for guiding both early detection and therapy of human cancer.

Extremely low frequency (ELF) pulsed-gradient magnetic fields inhibit malignant tumour growth at different biological levels.

Extremely low frequency (ELF) pulsed-gradient magnetic field (with the maximum intensity of 0.6-2.0 T, gradient of 10-100 T.M(-1), pulse width of 20-200 ms and frequency of 0.16-1.34 Hz treatment of mice can inhibit murine malignant tumour growth, as seen from analyses at different hierarchical levels, from organism, organ, to tissue, and down to cell and macromolecules. Such magnetic fields induce apoptosis of cancer cells, and arrest neoangiogenesis, preventing a supply developing to the tumour. The growth of sarcomas might be amenable to such new method of treatment.