Optimization of Cryopreservation Protocols for Cardiovascular Tissue

The purpose of this research was to determine the effects of cryopreservation on the physical, biochemical and cellular aspects of heart valve tissue. The present study demonstrated that radiolabeled proline accumulation provides a quantitative estimate of total cellular metabolic viability. Radiolabeled inulin was demonstrated to be a useful marker for extracellular tissue space. Assessment of metabolic viability of the cellular population of leaflet tissue as a function of procurement and processing revealed that proline accumulation declined with increasing warm and cold ischemic times. Amphotericin B and streptomycin were toxic to the cells. Cefoxitin, lincomycin, polymyxin B, vancomycin and penicillin had no apparent effect on viability of cells in heart valve tissue. The study also revealed that antibiotic solution (amphotericin B, cefoxitin, polymyxin B, lincomycin, vancomycin) utilized to disinfect tissue was able to kill E. coli, S. aureus, S. epidermidis, S. pneumoniae, C. peifiingens, but not S. faecalis after these bacteria were incubated with antibiotic solution for 24 or 48 hrs at 4°C. The cryoprotectants, dimethyl sulfoxide and glycerol were shown to reduce cellular metabolic viability when heart valve leaflets were incubated in RPMI 1640 medium supplemented with 10% fetal calf serum and either 10% Me2SO or 15% glycerol over 180 minutes at both 4°C and 37°C. Incubation of tissue for 10 minutes in concentrations of Me2SO and glycerol greater than 5% resulted in a significant reduction in proline accumulation at both 4°C and 37°C. The results revealed that penetration rates of both Me2SO and glycerol at 37°C were faster than at 4°C. After step-wise dilution to remove the cryoprotectants, there was still 0.25 M Me2SO and 0.2 M glycerol in the porcine aortic conduit tissue, respectively. The results demonstrated that cryopreserved human heart valve tissue, plunged into liquid nitrogen for as little as 5 minutes, appears to have numerous microffactures over the surfaces of the tissue, penetrating into the collagen / proteoglycan matrix. Thawing at 37°C and 42°C resulted in low percentage of nonviable cells, whereas thawing at 4°C, 20°C, or 75°C resulted in much higher percentage of nonviable cells. Assessment of the tendency of heart valve tissue to calcify was performed by measuring the ability of the tissue to induce alkaline phosphatase activities in fibroblast cell cultures. Porcine heart valve tissue with prolonged warm ischemic time, cold ischemic time and amphotericin B treatment induced significantly higher alkaline phosphatase activities than fresh porcine heart valve tissue

Investigating Uncertainty Calibration of Aligned Language Models under the Multiple-Choice Setting

Despite the significant progress made in practical applications of aligned language models (LMs), they tend to be overconfident in output answers compared to the corresponding pre-trained LMs. In this work, we systematically evaluate the impact of the alignment process on logit-based uncertainty calibration of LMs under the multiple-choice setting. We first conduct a thoughtful empirical study on how aligned LMs differ in calibration from their pre-trained counterparts. Experimental results reveal that there are two distinct uncertainties in LMs under the multiple-choice setting, which are responsible for the answer decision and the format preference of the LMs, respectively. Then, we investigate the role of these two uncertainties on aligned LM's calibration through fine-tuning in simple synthetic alignment schemes and conclude that one reason for aligned LMs' overconfidence is the conflation of these two types of uncertainty. Furthermore, we examine the utility of common post-hoc calibration methods for aligned LMs and propose an easy-to-implement and sample-efficient method to calibrate aligned LMs. We hope our findings could provide insights into the design of more reliable alignment processes for LMs

MFI2-AS1 enhances the survival of esophageal cancer cell via regulation of miR-331-3p/SOX4

Purpose: To investigate the specific role of melanotransferrin antisense RNA (MFI2-AS1) in esophageal cancer (EC) progression. Methods: The differential expression of MFI2-AS1 in EC tissues and cells was determined using quantitative reverse transcription–polymerase chain reaction (qRT-PCR). Silencing MFI2-AS1 was performed by transfection with specific short hairpin RNAs targeting MFI2-AS1. The 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT) and flow cytometry (FC) were used to assess cell viability and apoptosis of EC cells, respectively. The sponging microRNA (miRNA) of MFI2-AS1 was validated using luciferase activity and RNA immunoprecipitation assays while the downstream target gene of the sponging miRNA was evaluated by luciferase activity assay. Results: MFI2-AS1 was significantly enhanced in EC tissues (p < 0.01) and indicated a poor prognosis in EC patients. Knockdown of MFI2-AS1 in EC cells decreased cell viability and promoted cell apoptosis of EC cells. Functionally, MFI2-AS1 targeted miR-331-3p, and sex-determining region on Ychromosome-related high-mobility-group box4 (SOX4) was identified as a target gene of miR-331-3p. Ectopic expression of SOX4  counteracted the suppressive effect of MFI2-AS1 knockdown on EC cell viability and stimulative effect on EC cell apoptosis. Conclusion: The pro-oncogenic effect of MFI2-AS1 on EC progression occurs via the regulation of the miR-331-3p/SOX4 axis, providing a new potential therapeutic target for EC

Thinking on the Reasons and Countermeasures of the Failure and Misrepresentation of Science and Technology Transmission

This paper makes a comparative analysis of the phenomena of communication failure and misrepresentation in the East and the West history of science and technology communication. Based on the analysis, the authors find out the causes of this phenomenon and puts forward their own thinking and countermeasures. They expect to arouse the attention of scientific and technological media workers, so as to better inherit the knowledge and wisdom of human beings