Functional activity of the carboxyl-terminally extended oxytocin precursor Peptide during cardiac differentiation of embryonic stem cells

The hypothalamic post-translational processing of oxytocin (OT)-neurophysin precursor involves the formation of C-terminally extended OT forms (OT-X) that serve as intermediate prohormones. Despite abundant expression of the entire functional OT system in the developing heart, the biosynthesis and implication of OT prohormones in cardiomyogenesis remain unknown. In the present work, we investigated the involvement of OT-X in cardiac differentiation of embryonic stem (ES) cells. Functional studies revealed the OT receptor-mediated cardiomyogenic action of OT-Gly-Lys-Arg (OT-GKR). To obtain further insight into the mechanisms of OT-GKR-induced cardiac effects, we generated ES cell lines overexpressing the OT-GKR gene and enhanced green fluorescent protein (EGFP). The functionality of the OT-GKR/EGFP construct was assessed by fluorescence microscopy and flow cytometry, with further confirmation by radioimmunoassay and immunostaining. Increased spontaneously beating activity of OT-GKR/EGFP-expressing embryoid bodies and elevated expression of GATA-4 and myosin light chain 2v cardiac genes indicated an inductive effect of endogenous OT-GKR on ES cell-derived cardiomyogenesis. Furthermore, patch-clamp experiments demonstrated induction of ventricular phenotypes in OT-GKR/EGFP-transfected and in OT-GKR-treated cardiomyocytes. Increased connexin 43 protein in OT-GKR/EGFP-expressing cells further substantiated the evidence that OT-GKR modifies cardiac differentiation toward the ventricular sublineage. In conclusion, this report provides new evidence of the biological activity of OT-X, notably OT-GKR, during cardiomyogenic differentiation.     

Diagnostic performance of four SARS-CoV-2 antibody assays in patients with COVID-19 or with bacterial and non-SARS-CoV-2 viral respiratory infections

European Journal of Clinical Microbiology & Infectious Diseases - SARS-CoV-2 antibody assays are used for epidemiological studies and for the assessment of vaccine responses in highly...     

Correction to: Diagnostic performance of four SARS-CoV-2 antibody assays in patients with COVID-19 or with bacterial and non-SARS-CoV-2 viral respiratory infections

European Journal of Clinical Microbiology & Infectious Diseases -     

The function of type I interferons in antimicrobial immunity

Type I interferons (IFN-alpha and IFN-beta) were originally described as potent antiviral substances, which are produced upon infection of animal cells with viruses. Despite a large body of literature that has accumulated during the past 25 years, their regulatory function in the immune system is still much less appreciated. Recent studies have highlighted the production of type I IFNs, their function in the immune response to infectious agents and the target cells of these interferons. Type I IFNs clearly affect the release of proinflammatory cytokines or nitric oxide by dendritic cells and macrophages, the capacity of type II interferon (IFN-gamma) to activate phagocytes, the differentiation of T helper cells and the innate control of non-viral pathogens.     

αβ and γδ T cell subsets in chronic renal failure in children on dialysis treatment

BACKGROUND: Impaired immunity, particularly cell-mediated, is one of the features of chronic renal failure. This also concerns impaired T cell dependent responsiveness. METHODS: The expression of T cell surface antigens (CD3, CD25, TCRalphabeta, TCRgammadelta) was evaluated on peripheral blood (PB) mononuclear cells using two-color flow cytometry in 10 children on continuous ambulatory peritoneal dialysis (CAPD) and in 13 children on maintenance hemodialysis (HD) with polysulfone and cuprophane dialysers. RESULTS: In HD children absolute numbers of leukocytes, lymphocytes, CD3+, alphabeta, gammadelta T cells and a percentage of gammadelta T cells were decreased versus healthy children. Also, we observed a relative increase of CD3+, CD3+/CD25+ and alphabeta T cells after sessions with cuprophane membranes, and an increase of CD3+/CD25+, alphabeta T cell percentages after sessions with the polysulfone membranes. Additionally we found a decrease of both relative and absolute numbers of gammadelta T cells after HD with polysulfone. In CAPD children we found declined absolute numbers of total lymphocytes, CD3+ and alphabeta T cells and higher relative values of CD3+ and alphabeta T cells versus controls. CONCLUSIONS: The T cell depletion in chronic renal failure (CRF) patients primarily results from uremic-related toxicities, rather than from CAPD or HD-related incompatibilities. We showed a significant decrease of gammadelta T cells in CRF patients on HD, that may be partly responsible for impaired T-dependent responsiveness in that group. The intradialytic changes of gammadelta Tcells may result from a different degree of biocompatibility during the application of various dialysis membranes.     

Perforator flap magnetic resonance angiography for reconstructive breast surgery: A review of 25 deep inferior epigastric and gluteal perforator artery flap patients

Purpose

To evaluate the accuracy of magnetic resonance angiography (MRA) for preoperative mapping of rectus and gluteal muscle perforating arteries prior to autologous flap breast reconstruction.

Materials and Methods

Preoperative MRA on 25 consecutive patients undergoing perforator artery‐based autologous breast reconstruction was performed at 1.5 T using 3D liver accelerate volume acquisition (LAVA) of abdominal or gluteal regions acquired during injection of 20 mL of gadobenate dimeglumine with bolus timing optimized using MR fluoroscopy or SmartPrep. Perforator artery size and coordinates relative to umbilicus or top of gluteal crease on 3D MRA were compared to findings at surgery. Reconstructed breast volume estimates from MRA were also compared to weights at harvesting.

Results

In all, 132 perforator arteries were found at surgery to be located within 1 cm of the coordinates measured on MRA and were surgically verified to be suitable for flap perfusion. Surgery verified the arterial course and caliber through the rectus and gluteal muscles visualized on MRA in 48 of 49 arteries. Volume rendering of 3D MRA predicted a breast reconstruction volume with a mean difference of 47 g compared to measurements at harvesting.

Conclusion

MRA accurately maps rectus and gluteal muscle perforator arteries for preoperative planning of autologous flaps for breast reconstruction. J. Magn. Reson. Imaging 2010;31:1176–1184. © 2010 Wiley‐Liss, Inc.     

Insights into the kinetics of Ca2+-regulated contraction and relaxation from myofibril studies

Muscle contraction results from force-generating interactions between myosin cross-bridges on the thick filament and actin on the thin filament. The force-generating interactions are regulated by Ca²⁺ via specialised proteins of the thin filament. It is controversial how the contractile and regulatory systems dynamically interact to determine the time course of muscle contraction and relaxation. Whereas kinetics of Ca²⁺-induced thin-filament regulation is often investigated with isolated proteins, force kinetics is usually studied in muscle fibres. The gap between studies on isolated proteins and structured fibres is now bridged by recent techniques that analyse the chemical and mechanical kinetics of small components of a muscle fibre, subcellular myofibrils isolated from skeletal and cardiac muscle. Formed of serially arranged repeating units called sarcomeres, myofibrils have a complete fully structured ensemble of contractile and Ca²⁺ regulatory proteins. The small diameter of myofibrils (few micrometres) facilitates analysis of the kinetics of sarcomere contraction and relaxation induced by rapid changes of [ATP] or [Ca²⁺]. Among the processes studied on myofibrils are: (1) the Ca²⁺-regulated switch on/off of the troponin complex, (2) the chemical steps in the cross-bridge adenosine triphosphatase cycle, (3) the mechanics of force generation and (4) the length dynamics of individual sarcomeres. These studies give new insights into the kinetics of thin-filament regulation and of cross-bridge turnover, how cross-bridges transform chemical energy into mechanical work, and suggest that the cross-bridge ensembles of each half-sarcomere cooperate with each other across the half-sarcomere borders. Additionally, we now have a better understanding of muscle relaxation and its impairment in certain muscle diseases.     

Histological evidence concerning the osseointegration of titanium implants in the fractured rabbit femur

Stabilization of the broken bone is achieved using biocompatible materials. Since histology is still considered the gold standard technique for the assessment of bone formation around metallic implants, this report investigated the titanium implant integration in the accidentally broken bone in rabbits. The experimental protocol was reviewed and approved by the Ethical Committee of the Faculty of Medicine and Pharmacy Oradea, Romania. Holes were drilled in the diaphysis of the femur, and titanium implants were inserted in the created bone defect. In two subjects, fractures occurred on days two and three after the metallic alloy implantation. The other two rabbits presented no fractures following the surgical procedure. The rabbits were euthanized and the bones (with metallic implants) were harvested for histopathological investigation. Following decalcification, the bone samples were processed using the standard paraffin technique and stained by Goldner’s trichrome procedure. In subjects with a perfect immobilization of the titanium implants, the osseointegration occurred with minimal callus formation (i.e. primary cortical healing). In rabbits with bone fractures, the callus was more exuberant. A progressive replacement of the granulation tissue with hyaline cartilage and woven bone occurred soon after. The former aspects suggested an indirect metaplasia in the created callus. In all subjects, no inflammatory cells were identified in the created callus. The bone regeneration occurred either by primary cortical healing (in perfectly immobilized titanium implants) or by a process similar to the endochondral ossification (in poorly immobilized titanium implants following accidental post-implantation bones fracture).