Explore the vast range of titles available.

The aim of this study was to investigate the aggregation of red blood cells (RBCs) suspended in dextran solution at various levels of molecular mass. Dextran solutions at molecular mass 40, 70, 100 and 500 kDa at concentration from 2 to 5 g/dL were used to suspend the RBCs. The radius and velocity of sedimenting RBC aggregates were investigated using image analysis. The radius and sedimentation velocity of aggregates increased initially, then decreased after achieving maxima. The maximal velocity of RBC aggregates showed a bell-shaped dependence on dextran molecular mass and concentration, whereas maximal radius showed monotonic increase with both factors. Difference between aggregate and solution density was estimated using aggregate radius and sedimentation velocity and dextran solution viscosity, and was consistent across most molecular mass and concentration levels. This allowed to calculate the porosity of aggregates and to show that it monotonically decreased with the increase in the solution density, caused by the increase in the dextran concentration. The results provide insight into the RBC aggregation process in solutions of proteins of different size, reflecting various pathological conditions. The currently reported data can be potentially applied to specific pathophysiological conditions giving an interpretation that is not yet fully discussed in the literature.

Community‑acquired pneumonia (CAP) still carries a high long‑term mortality. Free protoporphyrin in erythrocytes (FPP) is a well-recognized biomarker of erythropoietic porphyrias. However, it also reflects impaired heme synthesis, disturbances in iron metabolism, and inflammation-driven erythropoietic alterations, mechanisms particularly relevant in pneumonia. This pilot study aimed to evaluate, for the first time, the prognostic value of FPP and zinc protoporphyrin (ZnPP), measured in acetone extracts of erythrocytes using fluorescence analysis with 405 nm excitation, in predicting 100-day mortality among 66 patients hospitalized with CAP. The area under the ROC curve for FPP fluorescence in predicting mortality was 0.793 (95% CI 0.657–0.928; p  < 0.0001), with 63% sensitivity and 94% specificity. Elevated FPP fluorescence was associated with a tenfold higher mortality risk and over fifteenfold greater odds of death, even after adjustment for age and the Charlson Comorbidity Index (CCI). A single fluorescence measurement at 632 nm (F632) demonstrated identical prognostic accuracy to spectral deconvolution-derived FPP intensity. Furthermore, significant correlations were observed between F632 or FPP fluorescence intensities and multiple clinical parameters reflecting disease severity, systemic inflammation, and erythropoietic stress. Given its accessibility and prognostic potential, prospective studies should further validate the method presented to guide individualized clinical management in CAP.

The aim of this study was to examine the usefulness of time-resolved fluorescence spectroscopy in the evaluation of the oxidative processes in human plasma. To investigate the impact of oxidative stress on the fluorescence of plasma, five studied markers (thiobarbituric acid-reactive substances, ischemia modified albumin, carbonyl groups, hydrogen peroxide, advanced oxidation protein products) were chosen as oxidative damage approved markers. Our method presents several advantages over traditional methods as it is a direct, non-time-consuming, repeatable, and non-invasive technique that requires only simple pre-treatment of samples without additional reagents and the sample size needed for analysis is small. In principle, each modification of the protein in plasma can be expected to modify its fluorescence properties and hence its lifetime or intensity. The study involved 59 blood donors with no evidence of disease. The research was conducted at excitation wavelengths of 280 nm and 360 nm, and emission was measured at wavelengths of 350 nm and 440 nm, respectively. Our results, although preliminary, suggest that the application of fluorescence measurements can be considered as an effective marker of oxidative stress. Regression analyses showed that a notable growth in fluorescence intensity at 440 nm and a simultaneous decrease in fluorescence intensity and mean fluorescence lifetime at 350 nm are associated with higher levels of oxidative stress.

Oxidative stress induced by neutrophils and hypoxia in COVID-19 pneumonia leads to albumin modification. This may result in elevated levels of advanced oxidation protein products (AOPPs) and advanced lipoxidation end-products (ALEs) that trigger oxidative bursts of neutrophils and thus participate in cytokine storms, accelerating endothelial lung cell injury, leading to respiratory distress. In this study, sixty-six hospitalized COVID-19 patients with respiratory symptoms were studied. AOPPs-HSA was produced in vitro by treating human serum albumin (HSA) with chloramine T. The interaction of malondialdehyde with HSA was studied using time-resolved fluorescence spectroscopy. The findings revealed a significantly elevated level of AOPPs in COVID-19 pneumonia patients on admission to the hospital and one week later as long as they were in the acute phase of infection when compared with values recorded for the same patients 6- and 12-months post-infection. Significant negative correlations of albumin and positive correlations of AOPPs with, e.g., procalcitonin, D-dimers, lactate dehydrogenase, aspartate transaminase, and radiological scores of computed tomography (HRCT), were observed. The AOPPs/albumin ratio was found to be strongly correlated with D-dimers. We suggest that oxidized albumin could be involved in COVID-19 pathophysiology. Some possible clinical consequences of the modification of albumin are also discussed.

Several studies have indicated that COVID-19 can lead to alterations in blood rheology, including an increase in red blood cell aggregation. The precise mechanisms behind this phenomenon are not yet fully comprehended. The latest findings suggest that erythrocyte aggregation significantly influences microcirculation, causes the formation of blood clots in blood vessels, and even damages the endothelial glycocalyx, leading to endothelial dysfunction. The focus of this research lies in investigating the cellular factors influencing these changes in aggregation and discussing potential causes and implications in the context of COVID-19 pathophysiology. For this purpose, the aggregation of erythrocytes in a group of 52 patients with COVID-19 pneumonia was examined in a 70 kDa Dextran solution, which eliminates the influence of plasma factors. Using image analysis, the velocities and sizes of the formed aggregates were investigated, determining their porosity. This study showed that the process of erythrocyte aggregation in COVID-19 patients, independent of plasma factors, leads to the formation of more compact, denser, three-dimensional aggregates. These aggregates may be less likely to disperse under circulatory shear stress, increasing the risk of thrombotic events. This study also suggests that cellular aggregation factors can be responsible for the thrombotic disorders observed long after infection, even when plasma factors have normalized. The results and subsequent broad discussion presented in this study can contribute to a better understanding of the potential complications associated with increased erythrocyte aggregation.

Fluorescence lifetime measurements of blood or plasma offer valuable insights into the microenvironment and molecular interactions of fluorophores, particularly concerning albumin. Neutrophil- and hypoxia-induced oxidative stress in COVID-19 pneumonia patients leads to hyperinflammation, various oxidative modifications of blood proteins, and potential alterations in the fluorescence lifetime of tryptophan-containing proteins, especially albumin. The objective of this study was to investigate the efficacy of time-resolved fluorescence spectroscopy of blood and plasma as a prompt diagnostic tool for the early diagnosis and severity assessment of COVID-19-associated pneumonia. This study examined a cohort of sixty COVID-19 patients with respiratory symptoms. To investigate whether oxidative stress is the underlying cause of the change in fluorescence lifetime, human serum albumin was treated with chloramine T. The time-resolved spectrometer Life Spec II (Edinburgh Instruments Ltd., Livingston, UK), equipped with a sub-nanosecond pulsed 280 nm diode, was used to measure the fluorescence lifetime of blood and plasma. The findings revealed a significant reduction in the fluorescence lifetime of blood (diluted 200 times) and plasma (diluted 20 times) at 360 nm in COVID-19 pneumonia patients compared with their respective values recorded six months post-infection and those of healthy individuals. Significant negative correlations were observed between the mean fluorescence lifetime of blood and plasma at 360 nm and several severity biomarkers and advanced oxidation protein products, while a positive correlation was found with albumin and the albumin–globulin ratio. The time-resolved fluorescence spectroscopy method demonstrates the potential to be used as a preliminary screening technique for identifying patients who are at risk of developing severe complications. Furthermore, the small amount of blood required for the measurements has the potential to enable a rapid fingerstick blood test.

Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) may contribute to venous thromboembolism (VTE) with adverse effects on the course of COVID-19. The purpose of this study was to investigate an incidence and risk factors for VTE in patients hospitalized for COVID-19 in a non-intensive care unit (non-ICU). Consecutive adult patients with COVID-19 hospitalized from November 2021 to March 2022 in the isolation non-ICU at our center were included in the study. Incidence of VTE including pulmonary embolism (PE) and deep vein thrombosis (DVT), clinical characteristics, and D-dimer plasma levels during the hospitalization were retrospectively evaluated. Among the 181 patients (aged 68.8 ± 16.2 years, 44% females, 39% Delta SARS-CoV-2 variant, 61% Omicron SARS-CoV-2 variant), VTE occurred in 29 patients (VTE group, 16% of the entire cohort). Of them, PE and DVT were diagnosed in 15 (8.3% of the entire cohort) and 14 (7.7%) patients, respectively. No significant differences in clinical characteristics were observed between the VTE and non-VTE groups. On admission, median D-dimer was elevated in both groups, more for VTE group (1549 ng/mL in VTE vs. 1111 ng/mL in non-VTE, p = 0.09). Median maximum D-dimer was higher in the VTE than in the non-VTE group (5724 ng/mL vs. 2200 ng/mL, p < 0.005). In the univariate analysis, systemic arterial hypertension and the need for oxygen therapy were predictors of VTE during hospitalization for COVID-19 (odds ratio 2.59 and 2.43, respectively, p < 0.05). No significant associations were found between VTE risk and other analyzed factors; however, VTE was more likely to occur in patients with a history of VTE, neurological disorders, chronic pulmonary or kidney disease, atrial fibrillation, obesity, and Delta variant infection. Thromboprophylaxis (83.4% of the entire cohort) and anticoagulant treatment (16.6%) were not associated with a decreased VTE risk. The incidence of VTE in patients hospitalized in non-ICU for COVID-19 was high despite the common use of thromboprophylaxis or anticoagulant treatment. A diagnosis of arterial hypertension and the need for oxygen therapy were associated with an increased VTE risk. Continuous D-dimer monitoring is required for the early detection of VTE.

A method of rapidly pointing out the risk of developing persistent pulmonary fibrosis from a sample of blood is extraordinarily needed for diagnosis, prediction of death, and post-infection prognosis assessment. Collagen scar formation has been found to play an important role in the lung remodeling following SARS-CoV-2 infection. For this reason, the concentration of collagen degradation products in plasma may reflect the process of lung remodeling and determine the extent of fibrosis. According to our previously published results of an in vitro study, an increase in the concentration of type III collagen degradation products in plasma resulted in a decrease in the fluorescence lifetime of plasma at a wavelength of 450 nm. The aim of this study was to use time-resolved fluorescence spectroscopy to assess pulmonary fibrosis, and to find out if the lifetime of plasma fluorescence is shortened in patients with COVID-19. The presented study is thus far the only one to explore the fluorescence lifetime of plasma in patients with COVID-19 and pulmonary fibrosis. The time-resolved spectrometer Life Spec II with the sub-nanosecond pulsed 360 nm EPLED® diode was used in order to measure the fluorescence lifetime of plasma. The survival analysis showed that COVID-19 mortality was associated with a decreased mean fluorescence lifetime of plasma. The AUC of mean fluorescence lifetime in predicting death was 0.853 (95% CI 0.735–0.972, p < 0.001) with a cut-off value of 7 ns, and with 62% sensitivity and 100% specificity. We observed a significant decrease in the mean fluorescence lifetime in COVID-19 non-survivors (p < 0.001), in bacterial pneumonia patients without COVID-19 (p < 0.001), and in patients diagnosed with idiopathic pulmonary fibrosis (p < 0.001), relative to healthy subjects. Furthermore, these results suggest that the development of pulmonary fibrosis may be a real and serious problem in former COVID-19 patients in the future. A reduction in the mean fluorescence lifetime of plasma was observed in many patients 6 months after discharge. On the basis of these data, it can be concluded that a decrease in the mean fluorescence lifetime of plasma at 450 nm may be a risk factor for mortality, and probably also for pulmonary fibrosis in hospitalized COVID-19 patients.

Patients with spinal cord injury (SCI) are at an increased risk of deep vein thrombosis (DVT). This study aims at assessing usefulness of D-dimer and compressive Doppler ultrasonography (CDUS) for detecting DVT in patients undergoing rehabilitation at various time-points post-SCI. One-hundred forty-five patients were divided into three groups based on time elapsed since SCI: I (≥3 weeks to 3 months), II (≥3 to 6 months), and III (≥6 months). On admission, D-dimer plasma level measurement and CDUS of the lower limbs venous system were performed. DVT was diagnosed using CDUS in 15 patients (10.3% of entire group), more frequently in group I (22.2% of group) and II (11.7%) compared to group III (1.5%). Most DVT patients received thromboprophylaxis (80%) and were asymptomatic or mildly symptomatic (60%). Median D-dimer was elevated in patients with DVT from all groups, and also patients without DVT from groups I and II, but not group III. D-dimers were higher in patients with DVT than without DVT in the entire group (p = 0.001) and group I (p = 0.02), but not in groups II and III. The risk of DVT in SCI patients undergoing rehabilitation and thromboprophylaxis including asymptomatic or mildly symptomatic cases, is high within 6 months post-injury, and especially within 3 months. Measurement of D-dimer level should be complemented by routine CDUS for detecting DVT within 6 months post-SCI. Over 6 months, the usefulness of D-dimer screening alone is better for DVT detection.