Search results for "erythrocyte"
showing 10 items of 370 documents
Mode of primary binding to target membranes and pore formation induced by Vibrio cholerae cytolysin (hemolysin).
1997
Vibrio cholerae cytolysin (VCC) is produced by many non-choleratoxigenic strains of V. cholerae, and possibly represents a relevant pathogenicity determinant of these bacteria. The protein is secreted as a pro-toxin that is proteolytically cleaved to yield the active toxin with a molecular mass of approximately 63 kDa. We here describe a simple procedure for preparative isolation of mature VCC from bacterial culture supernatants, and present information on its mode of binding and pore formation in biological membranes. At low concentrations, toxin monomers interact with a high-affinity binding site on highly susceptible rabbit erythrocytes. This as yet unidentified binding site is absent on…
Cell cooperation in coelomocyte cytotoxic activity of Paracentrotus lividus coelomocytes
2007
The coelomic fluid from the sea urchin Paracentrotus lividus contains several coelomocyte types including amoebocytes and uncoloured spherulocytes involved in immune defences. In the present paper, we show a Ca(2+)-dependent cytotoxic activity for the unfractionated coelomocytes assayed in vitro, with rabbit erythrocytes and the K562 tumour cell line. In a plaque-forming assay, whole coelomocyte preparations as well as density gradient separated coelomocyte populations revealed that cell populations enriched in uncoloured spherulocytes, exerted high cytotoxic activity by releasing lysins in the presence of amoebocytes. This cooperative effect could be dependent on soluble factors released b…
Clinical characteristics of COVID-19 patients in Latvia under low incidence in Spring 2020
2020
ABSTRACTBackgroundCOVID-19 is a new infectious disease with severe disease course and high mortality in some groups. Blood tests on admission to the hospital can be useful for stratification of patients and timely correction. Our study investigated the clinical features of COVID-19 patients in Latvia and differences in blood tests in groups with different disease severity.MethodsThe retrospective study included 100 patients hospitalized in Riga East Clinical University Hospital in Spring 2020. The severity of the disease course was classified by the presence of pneumonia and its combination with respiratory failure. We have assessed blood cells’ count, hemoglobin, hematocrit, erythrocyte se…
Extracorporeal circulation activates endothelial nitric oxide synthase in erythrocytes.
2007
Background Extracorporeal circulation used in cardiopulmonary bypass and hemodialysis is often associated with severe hypotension, which is an important predictor for mortality and morbidity. One pathophysiological hypothesis includes nitric oxide (NO) generation. Recently, a functional NO synthase (endothelial type NO synthase [eNOS]), was found to be expressed in human red blood cells. However, to date, activation of red blood cell eNOS has not been shown. We hypothesized that eNOS in circulating red blood cells might be activated during extracorporeal circulation and thus contribute to hypotension through vasodilation upon NO release. Methods We collected blood samples from 28 patients e…
ATR-FTIR spectroscopy as a quality control system for monitoring the storage of blood products
2021
Blood screening is a fundamental part of disease diagnosis and monitoring health. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy offers an innovative solution to streamlining the process, especially for multianalyte detection in aqueous samples. However, samples always undergo a storage phase before they are processed for testing and blood transfusion. In this study, we investigated the effect of standard storage procedures on the macromolecular composition of whole blood, and plasma collected in blood tubes for diagnostic purposes and initial screening of blood products. Periphery blood samples were collected from 10 volunteers and then stored for 14 days a…
Factors affecting the amount and the mode of merocyanine 540 binding to the membrane of human erythrocytes. A comparison with the binding to leukemia…
1995
Abstract In the presence of albumin Merocyanine 540 (MC540) exhibits a very limited binding to the outer surface of the membrane of normal erythrocytes, whereas pronounced binding is observed to leukemia cells. To find out whether this difference is due to differences in the composition or structural organization of the cell membrane we analyzed effects of a number of covalent and non-covalent perturbations of the red cell membrane on the binding and fluorescence characteristics of membrane-bound MC540. It is shown that exposure of the cells to cationic chlorpromazine, neuraminidase or photodynamic treatment with AlPcS 4 as sensitizer caused a limited increase (30–50%) of MC540 binding, tog…
Regulatory effects of polyamines on membrane-bound acetylcholinesterase
1974
The effects of putrescene, spermidine and spermine on membrane-bound acetylcholinesterase from human erythrocyte ‘ghosts’ and the solubilized enzyme of the electric organ of the electric eel were studied by kinetic methods. Measurements were made by using a photometric method which made it possible to record the enzyme reaction in the steady-state phase. Substrate-concentration-dependent activation and inhibition of acetylcholinesterase by polyamines is similar to that by Na+, K+, Ca2+, Mg2+ and certain quaternary and bisquaternary amines. The kinetics suggest an allosteric reaction mechanism. On the basis of the kinetic results a role for the polyamines as modulators of synaptic acetylchol…
Kinetics of streptolysin O self-assembly.
1995
Streptolysin O is a member of a family of membrane-damaging toxins that bind to cell membranes containing cholesterol and then polymerize to form large pores. We have examined the kinetics of toxin action using 125I-labelled streptolysin O. Binding of toxin monomers to membranes displays first-order kinetics and is reversible; the rate of desorption from red cells shows a marked dependence on temperature. To study oligomerization, toxin was bound to erythrocytes at 0 degrees C. Oligomer formation was then triggered by a sudden temperature shift and stopped by solubilization of membranes with deoxycholate. While at moderately high streptolysin O concentrations oligomerization behaves as a re…
Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective Europe…
2022
BACKGROUND Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12���g���dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (���week 3) onwards. OBJECTIVE To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN A multicentre observational study. SETTING The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthe…