Silyl-heparin bonding improves the patency and in vivo thromboresistance of carbon-coated polytetrafluoroethylene vascular grafts

AbstractObjectivesOur purpose was to improve the performance of carbon-coated expanded polytetrafluoroethylene vascular grafts by bonding the grafts with silyl-heparin, a biologically active heparin analog, using polyethylene glycol as a cross-linking agent.Material and methodSilyl-heparin–bonded carbon-coated expanded polytetrafluoroethylene vascular grafts (Bard Peripheral Vascular, Tempe, Ariz), were evaluated for patency and platelet deposition 2 hours, 7 days, and 30 days after graft implantation in a canine bilateral aortoiliac artery model. Platelet deposition was determined by injection of autologous, 111Indium-radiolabeled platelets, followed by a 2-hour circulation period prior to graft explantation. Histologic studies were performed on a 2-mm longitudinal strip of each graft (7-day and 30-day groups). Heparin activity of the explanted silyl-heparin grafts was determined by using an antithrombin-III based thrombin binding assay.ResultsOverall chronic graft patency (7-day and 30-day groups) was 100% for the silyl-heparin bonded (16/16) grafts versus 68.75% for control (11/16) grafts (P = .043). Acute 2-hour graft patency was 100% for the silyl-heparin bonded (6/6) grafts versus 83.3% for control (5/6) grafts. Radiolabeled platelet deposition studies revealed a significantly lower amount of platelets deposited on the silyl-heparin grafts as compared with control grafts in the 30-day group (13.8 ± 7.18 vs 28.4 ± 9.73, CPM per cm2 per million platelets, mean ± SD, P = .0451, Wilcoxon rank sum test). In the 2-hour group of dogs, a trend towards a lower deposition of platelets on the silyl-heparin grafts was observed. There was no significant difference in platelet deposition between the two grafts in the 7-day group. Histologic studies revealed a significant reduction in intraluminal graft thrombus present on the silyl-heparin grafts as compared with control grafts in the 30-day group of animals. In contrast, there was no difference in amount of graft thrombus present on both graft types in the 7-day group of dogs. Pre-implant heparin activity on the silyl-heparin bonded grafts was 2.0 IU/cm2 (international units[IU]/cm2). Heparin activity remained present on the silyl-heparin grafts after explantation at all 3 time points (2 hours: above upper limit of assay, upper limit = 0.57, n = 6; 7 days: 0.106 ± 0.015, n = 5; 30 days: 0.007 ± 0.001, n = 5; mean ± SD, IU/cm2).ConclusionSilyl-heparin bonding onto carbon-coated expanded polytetrafluoroethylene vascular grafts resulted in (1) improved graft patency, (2) increased in vivo graft thromboresistance, and (3) a significant reduction in intraluminal graft thrombus. This graft may prove to be useful in the clinical setting.AbstractClinical relevanceExpanded polytetrafluoroethylene (ePTFE) remains the most commonly used prosthetic graft material in infrainguinal arterial reconstructions. Reported long-term patency rates of ePTFE bypass grafts are inferior to those observed with autogenous vein. Modification of the luminal surface of ePTFE bypass grafts may prevent early graft failure and ultimately improve long-term graft performance. Silyl-heparin is a biologically active heparin analog that is readily adsorbed onto hydrophobic surfaces while retaining its anticoagulant properties. Silyl-heparin bonding onto carbon-coated ePTFE grafts improves the patency and in vivo thromboresistance and results in a decrease in intraluminal graft thrombus. This graft may be useful in the clinical setting

Catch Bonds in Sickle Cell Disease: Shear-Enhanced Adhesion of Red Blood Cells to Laminin

Could the phenomenon of catch bonding—force-strengthened cellular adhesion—play a role in sickle cell disease, where abnormal red blood cell (RBC) adhesion obstructs blood flow? Here we investigate the dynamics of sickle RBCs adhering to a surface functionalized with the protein laminin (a component of the extracellular matrix around blood vessels) under physiologically relevant micro-scale flow. First, using total internal reflectance microscopy we characterize the spatial fluctuations of the RBC membrane above the laminin surface before detachment. The complex dynamics we observe suggest the possibility of catch bonding, where the mean detachment time of the cell from the surface initially increases to a maximum and then decreases as a function of shear force. We next conduct a series of shear-induced detachment experiments on blood samples from 25 sickle cell disease patients, quantifying the number and duration of adhered cells under both sudden force jumps and linear force ramps. The experiments reveal that a subset of patients does indeed exhibit catch bonding. By fitting the data to a theoretical model of the bond dynamics, we can extract the mean bond lifetime versus force for each patient. The results show a striking heterogeneity among patients, both in terms of the qualitative behavior (whether or not there is catch bonding) and in the magnitudes of the lifetimes. Patients with large bond lifetimes at physiological forces are more likely to have certain adverse clinical features, like a diagnosis of pulmonary arterial hypertension and intracardiac shunts. By introducing an in vitro platform for fully characterizing RBC-laminin adhesion dynamics, our approach could contribute to the development of patient-specific anti-adhesive therapies for sickle cell disease. The experimental setup is also easily generalizable to studying adhesion dynamics in other cell types, for example leukocytes or cancer cells, and can incorporate disease-relevant environmental conditions like oxygen deprivation

A Comprehensive Study of Phenotypic and Genotypic Techniques to Detect Metallo-β-lactamases in Carbapenem-resistant Escherichia coli (E. coli) and Klebsiella pneumoniae (KP) Strains Derived through Numerous Clinical Specimens in Advanced Health care Facilities

In recent years, an increase in Escherichia coli and Klebsiella pneumoniae resistant to carbapenem was reported globally. Due to their high prevalence and extensive range of medical conditions, Escherichia coli and Klebsiella pneumoniae are both confirmed to be major public health concerns. Furthermore, carbapenem resistance restricts treatment options for individuals infected with these bacteria. Consequently, early detection of carbapenem resistance is essential for starting effective therapy, achieving successful management, and avoiding the infection from spreading further in the future. This study’s objective was to identify the phenotypic and genotypic identification of Metallo-β-lactamases (MBL) in carbapenem-resistant E. coli and K. pneumoniae in advanced healthcare facilities. Meropenem resistance was tested in E. coli and K. pneumoniae using the Kirby-Bauer disc diffusion technique. MBL was discovered using a combination of Disc diffusion testing and the Modified Hodge Test. The Polymerase Chain Reaction was used to determine the genotypes of the bla NDM-1 genes that express these enzymes. Out of 427 strains, including 223 E. coli and 204 K. pneumoniae, 35 (8.2%) consisted of carbapenem-resistant, and 29 (82.85%) showed phenotypically verified as metallo-beta-lactamase producers by using the Combined disc test and 20 (57.14%) using the Modified Hodge test. Polymerase Chain Reaction tests for genes detect those three different strains all showed the bla NDM-1 gene. Carbapenemase production and MBL can be recognized with the help of phenotypic combination disc and MHT tests in labs. Since both tests showed 100% concordance, laboratories may use the less expensive CDT instead of the MHT. The current study supports institutional antibiotic stewardship programmes to manage antibiotic use and prevent CRE worldwide

Effective Numerical Schemes for Ill-Posed Inverse Problems

Our goal is the design and analysis of effective nu- merical schemes for solving linear inverse problems of the form Ax = yobs.Mathematics, Department ofHonors Colleg

Association of Serum Beta-Trace Protein Levels in Patients with Chronic Kidney Disease: A Case-control Study

Introduction: Chronic Kidney Disease (CKD) is common disorder showing decreased Glomerular Filtration Rate (GFR) value (<60 mL/min/1.73 m2). Because of limitations of creatinine as a biomarker of GFR, new alternative biomarkers are being investigated, such as Beta-Trace Protein (BTP) is low molecular weight proteins that are filtered by the glomeruli. Serum BTP have been shown to be more helpful for estimating GFR. Aim: To assess the role of Beta-Trace Protein (BTP) as a potential biomarker of Chronic Kidney Disease (CKD) in comparison to serum urea, serum creatinine, fasting blood sugar and Creatinine Clearance Rate (CCR). Materials and Methods: This case-control study was conducted at Government Medical College, Rajouri, Jammu and Kashmir, India, from February 2021 to December 2021. Total 50 known patients of kidney diseases and 50 healthy individuals above the age of 18 years were enrolled in the study. Blood samples were collected from all individuals and serum BTP, serum urea level, serum creatinine level, fasting blood sugar were measured. Correlation of BTP with serum urea level, serum creatinine level, Fasting Blood Glucose (FBG) level, and CCR was calculated by Pearson Correlation test. Results: In present study, 50 patients in case groups (33 male and 17 females) and 50 healthy controls (25 males and 25 females) were included. Among controls, the mean age of patients was 52.12±5.66 years and among cases 55.94±10.51 years. BTP level was increased two times (from 32.06±11.25 µg/ml to 66.36±27.80 µg/ml) in CKD patients than controls individuals. BTP level was positively correlated with serum urea level, serum creatinine level, and FBG level while negatively correlated with CCR. Conclusion: BTP may be a useful and reliable serum marker for identifying the magnitude of renal dysfunction in patients with CKD and may have its place beside serum creatinine as an alternative endogenous GFR marker

Integrating Deep Learning with Microfluidics for Biophysical Classification of Sickle Red Blood Cells Adhered to Laminin

Sickle cell disease, a genetic disorder affecting a sizeable global demographic, manifests in sickle red blood cells (sRBCs) with altered shape and biomechanics. sRBCs show heightened adhesive interactions with inflamed endothelium, triggering painful vascular occlusion events. Numerous studies employ microfluidic-assay-based monitoring tools to quantify characteristics of adhered sRBCs from high resolution channel images. The current image analysis workflow relies on detailed morphological characterization and cell counting by a specially trained worker. This is time and labor intensive, and prone to user bias artifacts. Here we establish a morphology based classification scheme to identify two naturally arising sRBC subpopulations—deformable and non-deformable sRBCs—utilizing novel visual markers that link to underlying cell biomechanical properties and hold promise for clinically relevant insights. We then set up a standardized, reproducible, and fully automated image analysis workflow designed to carry out this classification. This relies on a two part deep neural network architecture that works in tandem for segmentation of channel images and classification of adhered cells into subtypes. Network training utilized an extensive data set of images generated by the SCD BioChip, a microfluidic assay which injects clinical whole blood samples into protein-functionalized microchannels, mimicking physiological conditions in the microvasculature. Here we carried out the assay with the sub-endothelial protein laminin. The machine learning approach segmented the resulting channel images with 99.1±0.3% mean IoU on the validation set across 5 k-folds, classified detected sRBCs with 96.0±0.3% mean accuracy on the validation set across 5 k-folds, and matched trained personnel in overall characterization of whole channel images with R2 = 0.992, 0.987 and 0.834 for total, deformable and non-deformable sRBC counts respectively. Average analysis time per channel image was also improved by two orders of magnitude (∼ 2 minutes vs ∼ 2-3 hours) over manual characterization. Finally, the network results show an order of magnitude less variance in counts on repeat trials than humans. This kind of standardization is a prerequisite for the viability of any diagnostic technology, making our system suitable for affordable and high throughput disease monitoring

SDS-PAGE analysis of purified recombinant fusion proteins and their confirmation by immunoblotting with anti-His antibodies.

<p><b>(A)</b> SDS-PAGE analysis of purified full length recombinant AtCyp19-3, and deleted versions AtCyp19-3 _(35–176) and AtCyp19-3 _(71–176). Total proteins were isolated from recombinant <i>E</i>.<i>coli</i> BL21(DE3) before (UI) and after induction (I) with 0.5 mM IPTG, and purified by Ni-NTA affinity column. Arrows indicate the purified recombinant proteins. <b>(B)</b> Confirmation of the purified recombinant proteins (arrows) by immunoblotting with the anti-His antibodies. M: markers.</p