Mitochondrial dysfunction in long COVID: mechanisms, consequences, and potential therapeutic approaches.

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has introduced the medical community to the phenomenon of long COVID, a condition characterized by persistent symptoms following the resolution of the acute phase of infection. Among the myriad of symptoms reported by long COVID sufferers, chronic fatigue, cognitive disturbances, and exercise intolerance are predominant, suggesting systemic alterations beyond the initial viral pathology. Emerging evidence has pointed to mitochondrial dysfunction as a potential underpinning mechanism contributing to the persistence and diversity of long COVID symptoms. This review aims to synthesize current findings related to mitochondrial dysfunction in long COVID, exploring its implications for cellular energy deficits, oxidative stress, immune dysregulation, metabolic disturbances, and endothelial dysfunction. Through a comprehensive analysis of the literature, we highlight the significance of mitochondrial health in the pathophysiology of long COVID, drawing parallels with similar clinical syndromes linked to post-infectious states in other diseases where mitochondrial impairment has been implicated. We discuss potential therapeutic strategies targeting mitochondrial function, including pharmacological interventions, lifestyle modifications, exercise, and dietary approaches, and emphasize the need for further research and collaborative efforts to advance our understanding and management of long COVID. This review underscores the critical role of mitochondrial dysfunction in long COVID and calls for a multidisciplinary approach to address the gaps in our knowledge and treatment options for those affected by this condition.

Gravity sedimentation reveals functionally and morphologically different platelets in human blood.

In contrast to red blood cells, platelets float rather than sediment when a column of blood is placed in the gravitational field. By the analogy of erythrocyte sedimentation (ESR), it can be expressed with the platelet antisedimentation rate (PAR), which quantitates the difference in platelet count between the upper and lower halves of the blood column after 1 h of 1 g sedimentation. Venous blood samples from 21 healthy subjects were analyzed for PAR. After a 1-h sedimentation, the upper and lower fractions of blood samples were analyzed for platelet count, mean platelet volume (MPV), immature platelet fraction (IPF), and high-fluorescence IPF (H-IPF). The mechanisms behind platelet flotation were explored by further partitioning of the blood column, time-dependent measurements of platelet count and comparison with ESR. The structure and function of the platelets were assessed by electron microscopy (EM) and atomic force microscopy (AFM), and platelet aggregometry, respectively. Platelet antisedimentation is driven by density differences and facilitated by a size-exclusion mechanism caused by progressive erythrocyte sedimentation. The area under the curve (AUC) of the whole blood adenosine diphosphate (ADP) aggregation curves showed significant differences between the upper and lower samples (p < .005). AUC in the upper samples of 38% of healthy subjects exceeded the top of the normal range (53-122) suggesting that ascending platelets show an intensified ADP-induced aggregability ex vivo. H-IPF was significantly higher in the upper samples (p < .05). EM and AFM revealed that platelets in the upper samples were larger in volume and contained 1.6 times more alpha granules compared to platelets in the lower samples. Our results indicate that antisedimentation is able to differentiate platelet populations based on their structural and functional properties. Therefore, PAR may be a suitable laboratory parameter in various thromboinflammatory disorders.

It is less known that platelets do not sediment in response to gravitational force but float on the top of the blood column. This phenomenon is called antisedimentation, the rate of which, however, can be different, yet this feature has not been widely studied and used in clinical practice or diagnosis. We tested the idea that antisedimentation of platelets from venous blood samples can be a potential biomarker. We have found that platelet antisedimentation is driven by density differences and facilitated by a size-exclusion mechanism caused by progressive erythrocyte sedimentation and after 1-h upper and lower fractions develop. Interestingly, the aggregation curves showed significant differences between the upper and lower samples, suggesting that the ascending platelets show ex vivo hyperaggregability. Electron and atomic force microscopy revealed that platelets in the upper samples were larger in volume and contained more alpha granules than platelets in the lower samples. Subsequently, antisedimentation can be used to differentiate platelet populations based on their structural and functional properties; thus, it may be a promising biomarker for various thromboinflammatory disorders.

General Anesthesia-Related Drop in Diastolic Blood Pressure May Impact the Long-Term Outcome in Stroke Patients Undergoing Thrombectomy.

Background: Several factors affect the efficacy of endovascular thrombectomy (EVT); however, the anesthesia-related factors have not been fully explored. We aimed to identify independent predictors of outcome by analyzing procedural factors based on a multicentric stroke registry. Methods: Data of consecutive patients with acute ischemic stroke (AIS) were extracted from the prospective STAY ALIVE stroke registry. Demographic, clinical, and periprocedural factors including hemodynamic values were analyzed in patients undergoing thrombectomy with either general anesthesia (GA) or conscious sedation (CS). Independent predictors of outcome both at 30 and 90 days based on the modified Rankin Scale (mRS: 0−2 as favorable outcome) were also explored. Results: A total of 199 patients (GA: 76 (38%) vs. CS: 117 (59%); in addition, six patients were converted from CS to GA) were included. The minimum value of systolic, diastolic, and mean arterial pressure was significantly lower in the GA compared to the CS group, and GA was associated with a longer onset to EVT time and a higher drop in all hemodynamic variables (all, p < 0.001). A higher drop in diastolic blood pressure (DBP) was even independently associated with a poor 90-day outcome (p = 0.024). Conclusion: A GA-related drop in DBP may independently predict a poor long-term outcome in stroke patients undergoing thrombectomy.

Circulating Microvesicles in Convalescent Ischemic Stroke Patients: A Contributor to High-On-Treatment Residual Platelet Reactivity?

INTRODUCTION: Exploration of novel and effective antiplatelet strategies for the secondary prevention of ischemic stroke is utmost. Some platelet derived microparticles (PMVs) in convalescent stroke subjects were found to be predictive for the next vascular event. Patients with high-on-treatment platelet reactivity (HTPR) had a significantly higher risk for ischemic stroke. Here, we aimed to explore associations among circulating microparticles and responsivness to antiplatelet (clopidogrel) therapy. METHODS: A total of 18 patients on clopidogrel therapy due to secondary stroke prevention were rospectively recruited into this study. Twenty age-matched healthy subjects served as controls. Flow cytometric measurements of microparicles (MVs) and data analysis were performed on Beckman-Coulter FC-500 cytometer with CXP software. Besides, platelet aggregometry data were revealed. Both measurements were performed in whole blood and from the lower and upper blood fractions separated after 1-hour gravity sedimentation by the analogy with erythrocyte sedimentation rate. RESULTS: The total number of circulating MVs, and particularly the platelet derived CD42+ and PAC-1+ were significantly higher in post-stroke patients (p < 0.001). The platelet aggregation in the whole blood (area under the curve, AUC) showed a significant negative correlation with the total number of MPs in the lower blood sample after 1-hour gravity sedimentation (r = -0.650, p = 0.005). Next, we analyzed associations among MPs and aggregometry data obtained from clopidogrel responders and non-responders. Both, area under the curve (AUC) and velocity in the whole blood showed opposite correlation with the total number of MVs in the lower blood sample after 1-hour gravity sedimentation. Importantly, a significant negative correlation was observed for the velocity (r = -0.801, p = 0.005), but not for the AUC in responders. Platelet derived CD42+ and PAC-1+ MVs showed positive correlations with neutrophils in the lower blood sample (p = 0.008 and p = 0.006 respectively). CONCLUSIONS: Circulating MVs may allow to monitor the response to antiplatelet therapy in post-stroke patients. In addition, the link between platelet derived MVs and neutrophil granulocytes might become therapeutic targets in the future.

Novel Predictors of Future Vascular Events in Post-stroke Patients-A Pilot Study.

Introduction: A modified platelet function test (mPFT) was recently found to be superior compared to impedance aggregometry for selection of post-stroke patients with high on-treatment platelet reactivity (HTPR). We aimed to explore some peripheral blood cell characteristics as predictors of recurrent ischemic episodes. The predictive value of mPFT was also assessed in a cohort followed up to 36 months regarding recurrent ischemic vascular events. Methods: As a novelty, not only whole blood (WB), but after 1-h gravity sedimentation the separated upper (UB) and lower half blood (LB) samples were analyzed including neutrophil antisedimentation rate (NAR) in 52 post-stroke patients taking clopidogrel. Area under the curve (AUC, AUCupper and AUClower, respectively) was separately measured by Multiplate in the WB, UB and LB samples to characterize ex vivo platelet aggregation in the presence of ADP. Next, the occurrence of vascular events (stroke, acute coronary syndrome, ACS) were evaluated during 36-month follow-up. Results: A total of 11 vascular events (stroke n = 5, ACS n = 6) occurred during the follow-up period. The AUCupper was significantly higher in patients with recurrent stroke compared to those with uneventful follow-up (p = 0.03). The AUCupper with a cut-off value ≥70 based on the mPFT, was able to predict all stroke events (p = 0.01), while the total vascular events were independently predicted by NAR with a sensitivity of 82% and specificity of 88%. Conclusions: A combination of NAR reflecting the inflammatory state and AUCupper indicating HTPR may provide a better prediction of recurrent ischemic events suggesting a better selection of patients at risk, thus providing an individually tailored vascular therapy.

A novel approach of platelet function test for prediction of attenuated response to clopidogrel.

BACKGROUND: Elevated mean platelet volume (MPV) and immature platelet fraction (IPF) are predictive for vascular risk. Both can be associated with residual platelet reactivity. We aimed to explore associations among platelet characteristics and responder status in stroke patients on clopidogrel. METHODS: Blood samples from 46 patients and 15 healthy subjects were analyzed for platelet count, MPV, IPF, large cell ratio (LCR) and high-fluorsecent immature platelet fraction (H-IPF). As a novelty, not only whole blood, but upper and lower half blood samples after 1-hour gravity sedimentation were analyzed. Platelet aggregometry was used for the whole blood and separated samples to explore area under the curve (AUC) in patients and controls. RESULTS: The AUC of the whole blood showed significant differences compared to the upper and lower samples separated after 1-hour sedimentation in patients and controls (p < 0.001 and p = 0.005 respectively). Remarkably, AUC measured in the upper samples in 59% of patients on clopidogrel were exceeding the therapeutic range suggesting that ascending platelets exert aggregation in the presence of ADP. This observation was associated with increased MPV and LCR in the upper samples (both p = 0.04). Patients on clopidogrel were characterized as responders and non-responders and the percentage of H-IPF was significantly higher among non-responders compared to controls in the upper samples (p = 0.04). CONCLUSIONS: The modified platelet function test may help to stratify patients with high residual platelet reactivity.

[Personnel and material conditions of the Hungarian intensive care units dealing with organ donation]. / Magyarországi intenzív osztályok szervdonációval kapcsolatos személyi és tárgyi feltételei.

INTRODUCTION: At the end of 2016, the number of patients on the domestic transplant waiting list was twice as much as the number of the organ transplantations accomplished that year. The institutional prerequisites for functional organ donation programs are the sufficient number of personnel and the adequate material conditions to be provided in relation to the needs. AIM: The goal of the current study was to evaluate the professional environment in Hungary. METHOD: The Organ Coordination Office at the Hungarian National Blood Transfusion Service compiled a questionnaire survey on the personnel and material conditions of the intensive care units (ICUs) in Hungary in regards to organ donations. The survey applied an online questionnaire including 43 questions. In addition to the number of beds and employees, we investigated the tools needed for the legal and the medical diagnosis of brain death as well as the accessibility of examinations on the donor information form. The data collection spanned from 12 December 2016 to 30 June 2017. RESULTS: 59 intensive care units completed the questionnaire; the investigation involved 640 hospital beds, 816 physicians and 1252 nurses. In the daytime shift, 0.25 doctors and 0.41 nurses work on a patient bed at an average, while in the night shift, the figures are 0.11 and 0.33, respectively. 51.7% of the doctors are registered to access the National Non-Donor Registry, and brain death diagnosis committee is available in 83% of the hospitals. Among the medical imaging methods (cranial, abdominal-thoracic), CT scan in 71-73%, abdominal ultrasound in 75%, transthoracic echocardiograpy (TTE) in 37%, transoesophageal echocardiography (TEE) in 4%, bronchoscopy in 49%, coronarography in 19% are non-stop available, with instant interpretation in 75% of the cases. Transcranial Doppler (TCD) in 30%, four-vessel angiography in 45% and SPECT in 14% of the cases are available. More than 90% of the laboratory examinations on the donor information form are available 24 hours a day. CONCLUSION: The number of doctors and nurses did not change compared to our 2008 survey (0.18 doctors, 0.37 nurses/ICU beds in 2008), but the care of potential donors needs more resources and time. The standby availability of personnel and material conditions is a prerequisite for organ donation programs in order to save lives. Orv Hetil. 2018; 159(33): 1360-1367.

Relationship between Cardiac Troponin and Thrombo-Inflammatory Molecules in Prediction of Outcome after Acute Ischemic Stroke.

BACKGROUND: In patients with acute ischemic stroke (AIS) without cardiovascular complications, we investigated the association of serum concentration of cardiac troponin (high-sensitivity cardiac troponin T [hs-cTnT]) with thrombo-inflammatory markers. METHODS: Thirty-five patients with first-ever AIS were prospectively examined. Serum hs-cTnT was measured 6 and 24 hours after stroke, whereas S100B, high-sensitivity C-reactive protein (hsCRP), soluble CD40 ligand, tissue plasminogen activator (tPA), monocyte chemoattractant protein-1 (MCP-1), and P-selectin were measured 6 and 72 hours after stroke. Severity of stroke was assessed by the National Institutes of Health Stroke Scale (NIHSS) on admission, 24 hours later, and at discharge. RESULTS: Concentration of MCP-1 at 6 hours was higher in the serum of patients with worsened NIHSS by 24 hours (P = .009). Concentration of hs-cTnT at both 6 and 24 hours was higher, if NIHSS worsened by discharge (P = .026 and P = .001). A cutoff value for hs-cTnT measured at T24 greater than or equal to 9.4 predicted worsened NIHSS on discharge with a sensitivity of 81% and a specificity of 74% (area: .808, P = .002). Concentration of hs-cTnT at both 6 and 24 hours was also higher in nonsurvivors compared with survivors (P = .03, respectively), and correlated with (1) tPA levels at 6 hours (P = .001 and P = .002, respectively); (2) MCP-1 concentration at 6 hours (P = .01 and P = .015, respectively); and increased hsCRP levels at 72 hours (P = .01, respectively). Concentration of hs-cTnT at 24 hours was an independent predictor of worsened NIHSS at discharge (odds ratio: 1.58, 95% confidence interval: 1.063-2.370, P = .024). CONCLUSIONS: Elevated concentration of hs-cTnT measured 24 hours after AIS is an independent predictor of progressing neurologic deficit in patients without apparent myocardial damage, and also correlates with acute elevation of tPA and MCP-1.

[Guidelines for the treatment of traumatic brain injury - 2017]. / Baleseti agysérültek ellátásának irányelvei - 2017.

Traumatic brain injury (TBI) is recognized to be the main cause of death and disability in the first four decades representing a major socio-economical problem worldwide. Recent communications revealed a particularly worrying image about the quality of care for TBI in Hungary. For any improvement a systematic approach characterized by utilization of scientific evidence based guidelines forming the basis for close monitoring of the actual care are considered a prerequisite. In Hungary the first evidence based guidelines in the field of TBI have been issued by the National Society for Anesthesiology and Intensive Care more than two decades ago followed by joint guidelines of the Hungarian Neurosurgical Society and the Hungarian College of Neurosurgeons. These publications were primarily based on the work of the European Brain Injury Consortium as well as guidelines issued by the Brain Trauma Foundation. Recent renewal of the latter and a need to refresh the outdated national guidelines was met by a call from regulatory authorities to issue the updated version of the Hungarian TBI-guidelines. The present review is aimed to briefly summarize the most fundamental elements of the national head injury guidelines that would hopefully be officially issued in a far more detailed format soon.

Traumatic brain injury-induced autoregulatory dysfunction and spreading depression-related neurovascular uncoupling: Pathomechanisms, perspectives, and therapeutic implications.

Traumatic brain injury (TBI) is a major health problem worldwide. In addition to its high mortality (35-40%), survivors are left with cognitive, behavioral, and communicative disabilities. While little can be done to reverse initial primary brain damage caused by trauma, the secondary injury of cerebral tissue due to cerebromicrovascular alterations and dysregulation of cerebral blood flow (CBF) is potentially preventable. This review focuses on functional, cellular, and molecular changes of autoregulatory function of CBF (with special focus on cerebrovascular myogenic response) that occur in cerebral circulation after TBI and explores the links between autoregulatory dysfunction, impaired myogenic response, microvascular impairment, and the development of secondary brain damage. We further provide a synthesized translational view of molecular and cellular mechanisms involved in cortical spreading depolarization-related neurovascular dysfunction, which could be targeted for the prevention or amelioration of TBI-induced secondary brain damage.

Multi-modal magnetic resonance imaging in the acute and sub-acute phase of mild traumatic brain injury: can we see the difference?

Advanced magnetic resonance imaging (MRI) methods were shown to be able to detect the subtle structural consequences of mild traumatic brain injury (mTBI). The objective of this study was to investigate the acute structural alterations and recovery after mTBI, using diffusion tensor imaging (DTI) to reveal axonal pathology, volumetric analysis, and susceptibility weighted imaging (SWI) to detect microhemorrhage. Fourteen patients with mTBI who had computed tomography with negative results underwent MRI within 3 days and 1 month after injury. High resolution T1-weighted imaging, DTI, and SWI, were performed at both time points. A control group of 14 matched volunteers were also examined following the same imaging protocol and time interval. Tract-Based Spatial Statistics (TBSS) were performed on DTI data to reveal group differences. T1-weighted images were fed into Freesurfer volumetric analysis. TBSS showed fractional anisotropy (FA) to be significantly (corrected p<0.05) lower, and mean diffusivity (MD) to be higher in the mTBI group in several white matter tracts (FA=40,737; MD=39,078 voxels) compared with controls at 72 hours after injury and still 1month later for FA. Longitudinal analysis revealed significant change (i.e., normalization) of FA and MD over 1 month dominantly in the left hemisphere (FA=3408; MD=7450 voxels). A significant (p<0.05) decrease in cortical volumes (mean 1%) and increase in ventricular volumes (mean 3.4%) appeared at 1 month after injury in the mTBI group. SWI did not reveal microhemorrhage in our patients. Our findings present dynamic micro- and macrostructural changes occurring in the acute to sub-acute phase in mTBI, in very mildly injured patients lacking microhemorrhage detectable by SWI. These results underscore the importance of strictly defined image acquisition time points when performing MRI studies on patients with mTBI.

Brain injury biomarkers may improve the predictive power of the IMPACT outcome calculator.

Outcome prediction following severe traumatic brain injury (sTBI) is a widely investigated field of research. A major breakthrough is represented by the IMPACT prognostic calculator based on admission data of more than 8500 patients. A growing body of scientific evidence has shown that clinically meaningful biomarkers, including glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCH-L1), and αII-spectrin breakdown product (SBDP145), could also contribute to outcome prediction. The present study was initiated to assess whether the addition of biomarkers to the IMPACT prognostic calculator could improve its predictive power. Forty-five sTBI patients (GCS score≤8) from four different sites were investigated. We utilized the core model of the IMPACT calculator (age, GCS motor score, and reaction of pupils), and measured the level of GFAP, UCH-L1, and SBDP145 in serum and cerebrospinal fluid (CSF). The forecast and actual 6-month outcomes were compared by logistic regression analysis. The results of the core model itself, as well as serum values of GFAP and CSF levels of SBDP145, showed a significant correlation with the 6-month mortality using a univariate analysis. In the core model, the Nagelkerke R(2) value was 0.214. With multivariate analysis we were able to increase this predictive power with one additional biomarker (GFAP in CSF) to R(2)=0.476, while the application of three biomarker levels (GFAP in CSF, GFAP in serum, and SBDP145 in CSF) increased the Nagelkerke R(2) to 0.700. Our preliminary results underline the importance of biomarkers in outcome prediction, and encourage further investigation to expand the predictive power of contemporary outcome calculators and prognostic models in TBI.

[Diffusion tensor and functional MR imaging of severe traumatic craniocerebral injury at low magnetic field]. / Súlyos koponya-agy sérülés vizsgálata diffúziós tenzor es funkcionális MR-képalkotással alacsony téreron.

AIM OF THE STUDY: Presentation of diffusion tensor imaging (DTI) performed at low magnetic field (1 Tesla) in the algorithm of work-up of a patient suffering from severe traumatic brain injury (TBI). METHOD: DTI and functional MRI (fMRI) were applied at 1 Tesla for visualization of neural pathways and examination of sensory functions of a patient with severe TBI. DTI-measurement was also performed on a healthy patient for comparison. RESULTS: DTI acquired at low magnetic field yielded appropriate visualization of neural pathways. DTI confirmed the results of the clinical and fMRI examinations in the patient suffering from severe TBI. CONCLUSION: An optimized DTI can be useful in the examination of patients with TBI, moreover, it may also help in the establishment of diagnoses of other central nervous system diseases affecting neuronal pathways. The presented results suggest that DTI of appropriate quality can be performed at low magnetic field.

[Application of vertebroplasty, neuronavigation and kyphoplasty in the treatment of multiplex osteoporotic vertebral fractures--case report]. / Vertebroplastica, neuronavigáció es kyphoplastica alkalmazása poroticus eredetu multiplex kompressziós csigolyatörések kezelésében.

Vertebroplasty is a image-guided therapeutic procedure, consisting of an injection of acrylic cement through a bone biopsy needle into a vertebral body. Main indication for vertebroplasty is painful vertebral body compression fracture due to osteoporosis. The procedure is an efficient mean with high success in pain release and prevention of further collapse of the treated vertebrae; however, the technique does not allow to realign the spine. Kyphoplasty was designed to address the kyphotic deformity. It involves the percutaneous placement of an inflatable bone tamp into a vertebral body (VB). Restoration of VB height and kyphosis correction is achieved by inflation of the tamp with contrast material liquid. After deflation a cavity is created that eases the cement application. The most modern way of guidance in spinal surgery is neuronavigation--the use of frameless stereotaxy. The system reformats patient-specific CT images acquired prior surgery, performs image fusion with intraoperative plain X-ray. Before the operation, the surgeon may create surgical plan and simulate advancement of a virtual instrument along one or more surgical trajectories. During surgery, the system tracks the position of specialized surgical instruments. All three modalities mentioned above have been applied in the treatment of our patient suffered from multiple osteoporotic vertebral body compression fractures. Using kyphoplasty an almost total VB height restoration could be achieved. The pain relief was more than 50% after both operation.