The role of S100A9 in the interaction between pancreatic ductal adenocarcinoma cells and stromal cells.

BACKGROUND: A major feature of the microenvironment in pancreatic ductal adenocarcinoma (PDAC) is the significant amount of extracellular matrix produced by pancreatic stellate cells (PSCs), which have been reported to enhance the invasiveness of pancreatic cancer cells and negatively impact the prognosis. METHODS: We analyzed the data from two publicly available microarray datasets deposited in the Gene Expression Omnibus and found candidate genes that were differentially expressed in PDAC cells with metastatic potential and PDAC cells cocultured with PSCs. We studied the interaction between PDAC cells and PSCs in vitro and verified our finding with the survival data of patients with PDAC from the website of The Human Protein Atlas. RESULTS: We found that PSCs stimulated PDAC cells to secrete S100A9, which attracted circulatory monocytes into cancer tissue and enhanced the expression of programmed death-ligand 1 (PD-L1) on macrophages. When analyzing the correlation of S100A9 and PD-L1 expression with the clinical outcomes of patients with PDAC, we ascertained that high expression of S100A9 and PD-L1 was associated with poor survival in patients with PDAC. CONCLUSIONS: PSCs stimulated PDAC cells to secrete S100A9, which acts as a chemoattractant to attract circulatory monocytes into cancer microenvironment and induces expression of PD-L1 on macrophages. High expression of S100A9 and PD-L1 was associated with worse overall survival in a cohort of patients with PDAC.

Therapeutic Potential of Plasma Proteins Derived from Umbilical Cord Blood for Acute Liver Failure.

There are very limited clinically viable treatment options for acute liver failure, a life-threatening condition that rapidly progresses to loss of liver function. In this study, we aim to evaluate the therapeutic potential of UCBP for acute liver failure induced in a rat model by D-galactosamine (GalN). F344 rats were randomly divided into two groups (control and UCBP-treated) after GalN injection. The therapeutic effects of UCBP were evaluated based on survival rate, H&E staining, TUNEL, PCNA staining, and in vivo BrdU labeling. Hepatocyte proliferation and the therapeutic mechanisms of UCBP were examined with BrdU and Western blot assay in vitro. The survival rate in the UCBP-treated group was found to be increased compared to the control group (85 vs 55%, P = 0.029). UCBP treatment significantly decreased apoptosis and increased cell proliferation. These effects may be secondary to specific bioactive molecules in UCBP. In vitro experiments revealed that adiponectin is one of the key biologically active components of UCBP in facilitating this result and promoting hepatocyte proliferation. Furthermore, this effect is mediated by p38/ERK mitogen-activated protein kinase (MAPK) signaling pathways. Therefore, this uncomplicated and clinically accessible approach may serve as effective bridge therapy for acute liver failure.

Telehealth and digital health innovations: A mixed landscape of access.

In the wake of emergent natural and anthropogenic disasters, telehealth presents opportunities to improve access to healthcare when physical access is not possible. Yet, since the beginning of the COVID pandemic, lessons learned reveal that various populations in the United States do not or cannot adopt telehealth due to inequitable access. We explored the Digital Determinants of Health (DDoHs) for telehealth, characterizing the role of accessibility, broadband connectivity and electrical grids, and patient intersectionality. In addition to its role as an existing Social Determinant of Health, Policies and Laws directly and indirectly affect these DDoHs, making access more complex for marginalized populations. Digital systems lack the flexibility, accessibility, and usability to inclusively provide the essential services patients need in telehealth. We propose the following recommendations: (1) design technology and systems using accessibility and value sensitive design principles; (2) support a range of technologies and settings; (3) support multiple and diverse users; and (4) support clear paths for repair when technical systems fail to meet users' needs. Addressing these requires change not only from providers but also from the institutions providing these systems.

Different methods of detaching adherent cells and their effects on the cell surface expression of Fas receptor and Fas ligand.

In cell culture environment, some cells adhere firmly to the culture plates and may be vulnerable to cell detachment during passage. Therefore, it is important to harvest cells with a proper detaching method to maintain the viability of cells after detachment. Trypsinization is frequently used for cellular dissociation and detachment. However, most surface proteins and the extracellular matrix are degraded by enzymatic digestion. A mild cell detachment buffer, accutase, is recommended for the replacement of trypsin to dissociate adherent cells and thereby avoid cellular damage. In this study, we demonstrated that use of accutase for cellular detachment may compromise some surface proteins. Compared with ethylenediaminetetraacetic acid (EDTA)-based nonenzymatic cell dissociation buffers, accutase was associated with significant decreases in the surface Fas ligands and Fas receptors. Moreover, we found that accutase may be able to cleave surface Fas ligands into pieces. Our results also illustrated that surface proteins required 20 h to recover after accutase treatment. We demonstrated that using accutase to dissociate adherent cells compromised the expression of Fas ligands and Fas receptors on the cell surface. These findings indicate that it is important to choose suitable cell detachment buffers and allow cells to recover after detachment before experiments.

Umbilical cord blood plasma-derived exosomes as a novel therapy to reverse liver fibrosis.

BACKGROUND: Cirrhosis is a chronic liver disease whereby scar tissue replaces healthy liver parenchyma, leading to disruption of the liver architecture and hepatic dysfunction. Currently, there is no effective disease-modifying therapy for liver fibrosis. Recently, our group demonstrated that human umbilical cord blood (UCB) plasma possesses therapeutic effects in a rat model of acute liver failure. METHODS: In the current study, we tested whether exosomes (Exo) existed in UCB plasma and if they produced any antifibrotic benefits in a liver fibrosis model. RESULTS: Our results showed that UCB-Exo improved liver function and increased matrix metalloproteinase/tissue inhibitor of metalloproteinase degradation to reduce the degree of fibrosis. Moreover, UCB-Exo were found to suppress hepatic stellate cell (HSC) activity in vitro. These effects were associated with suppression of transforming growth factor-ß/inhibitor of DNA binding 1 signaling. CONCLUSIONS: These results further support that UCB-Exo have antifibrotic effects in mice with liver fibrosis and activated HSCs and may herald a new cell-free antifibrotic therapy.

Nonameric structures of the cytoplasmic domain of FlhA and SctV in the context of the full-length protein.

Type three secretion is the mechanism of protein secretion found in bacterial flagella and injectisomes. At its centre is the export apparatus (EA), a complex of five membrane proteins through which secretion substrates pass the inner membrane. While the complex formed by four of the EA proteins has been well characterised structurally, little is known about the structure of the membrane domain of the largest subunit, FlhA in flagella, SctV in injectisomes. Furthermore, the biologically relevant nonameric assembly of FlhA/SctV has been infrequently observed and differences in conformation of the cytoplasmic portion of FlhA/SctV between open and closed states have been suggested to reflect secretion system specific differences. FlhA has been shown to bind to chaperone-substrate complexes in an open state, but in previous assembled ring structures, SctV is in a closed state. Here, we identify FlhA and SctV homologues that can be recombinantly produced in the oligomeric state and study them using cryo-electron microscopy. The structures of the cytoplasmic domains from both FlhA and SctV are in the open state and we observe a conserved interaction between a short stretch of residues at the N-terminus of the cytoplasmic domain, known as FlhAL/SctVL, with a groove on the adjacent protomer's cytoplasmic domain, which stabilises the nonameric ring assembly.

Face, content, construct validity and training effect of touch surgery™ as a surgical decision-making trainer for novices in open appendicectomy.

BACKGROUND: Laparoscopic surgery has become the gold standard for many operations with significant benefits in morbidity and hospital recovery time. One such procedure is appendicectomy, which is overwhelmingly performed using the laparoscopic approach in the modern era. This has also meant that the number of cases involving traditional open appendicectomy has declined despite surgeons being expected to be able to convert to the open technique if required. One method to rehearse for theatre is the use of software applications. This paper investigates the validity of Touch Surgery™ as an education tool for surgical decision-making for novices, as well as its training effect in open appendicectomy. METHOD: 70 participants will be recruited, consisting of 60 medical students (novices) and 10 surgical consultants (experts). For face, content, and construct validity, first attempt scores on the Touch Surgery™ Open Appendicectomy Test Module will be compared between novices and experts. For the training effect and knowledge decline elements of the study, novices will be further randomised into either the low intervention (control) group who will complete the simulation once, or to the high intervention group who will complete the simulation six times, with both novice groups asked to repeat the test one week later. All participants will also be requested to complete questionnaires regarding the stimulation.

Multi-Channel Facial Photoplethysmography Sensing.

Motivated by the need for continuous cardiovascular monitoring, we present a system for performing photoplethysmography sensing at multiple facial locations. As a proof-of-concept, our system incorporates an optical sensor array into a wearable face mask form factor for application in a surgical hemodynamic monitoring use case. Here we demonstrate that our design can accurately detect pulse timing by validating estimated heart rate against ground truth electrocardiogram recordings. In an experiment across 10 experimental subjects, our system achieves an error standard deviation of 2.84 beats per minute. This system shows promise for performing non-invasive, continuous pulse waveform recording from multiple locations on the face.

Detection of tetrahydrobiopterin by LC-MS/MS in plasma from multiple species.

BACKGROUND: Tetrahydrobiopterin (BH4) is a naturally occurring pteridine and cofactor for a variety of enzymes, including phenylalanine-4-hydroxylase, nitric oxide synthetase and glyceryl ether monooxygenase. BH4 is readily oxidized to dihydrobiopterin and biopterin (B), however only BH4 can provide proper cofactor functions. BH4 is the active ingredient in Kuvan™ for the treatment of phenylketonuria. In order to measure BH4 in plasma from nonclinical and clinical samples with good accuracy, precision, sensitivity and robustness, an LC-MS/MS method was validated. To overcome the oxidation of BH4 in postcollection plasma, the approach was to measure the concentration of BH4 indirectly by measuring B concentration and applying an oxidation conversion ratio. Different endogenous levels of BH4 are determined in human, monkey, dog, rabbit, rat and mouse plasma. Furthermore, the conversion ratio of BH4 to B for each species is different and determined empirically. Plasma is transferred into cryogenic vials containing 0.1% dithioerythritol to prevent oxidation of BH4. The samples are then extracted and oxidized under basic conditions. B is measured with LC-MS/MS using negative ion mode. RESULTS: The method is accurate, and precise to within 15%. The lower limit of quantitation in matrix is 5, 50 or 100 ng/ml, depending on the species endogenous levels of BH4. The pharmacokinetics of a single oral dose at three concentrations of BH4 administered to C57BL/6 mice is presented. In this mouse study, the T(1/2) of BH4 in plasma was approximately 1.2 h. CONCLUSION: The validated LC-MS/MS method to determine plasma BH4 concentration described herein has been used to support many nonclinical and clinical toxicokinetic and pharmacokinetic studies. BH4 is sensitive to oxidation and has a complicated biology. The method successfully supported the approval of Kuvan for the treatment of phenylketonuria.