Lessons from the COVID-19 pandemic: Mortality impacts in Poland versus European Union.

With COVID-19 moving toward an endemic phase, it is worthwhile to identify lessons from the pandemic that can promote the effective strengthening of national health systems. We look at a single country, Poland, and compare it with the European Union (EU) to contrast approaches and outcomes. Among possible relevant indices, we examine characteristics of COVID-19-related mortality and excess all-cause mortality from March 2020 to February 2022. We demonstrate that both the numbers of COVID-related deaths and all-cause deaths in Poland were much higher than the EU average for most months in the study period. We juxtapose the percentage of fully vaccinated population and cumulative COVID-19 deaths per million people for EU Member States and show that typically higher vaccination rates are accompanied by lower mortality. We also show that, in addition to medical science, the use of a risk science toolbox would have been valuable in the management of the COVID-19 pandemic in Poland. Better and more widespread understanding of risk perception of the pandemic and the COVID-19 vaccines would have improved managing vaccine hesitancy, potentially leading to more effective pro-vaccination measures.

In search for mitochondrial biomarkers of Parkinson's disease: Findings in parkin-mutant human fibroblasts.

Most cases of Parkinson's disease (PD) are idiopathic, with unknown aetiology and genetic background. However, approximately 10 % of cases are caused by defined genetic mutations, among which mutations in the parkin gene are the most common. There is increasing evidence of the involvement of mitochondrial dysfunction in the development of both idiopathic and genetic PD. However, the data on mitochondrial changes reported by different studies are inconsistent, which can reflect the variability in genetic background of the disease. Mitochondria, as a plastic and dynamic organelles, are the first place in the cell to respond to external and internal stress. In this work, we characterized mitochondrial function and dynamics (network morphology and turnover regulation) in primary fibroblasts from PD patients with parkin mutations. We performed clustering analysis of the obtained data to compare the profiles of mitochondrial parameters in PD patients and healthy donors. This allowed to extract the features characteristic for PD patients fibroblasts, which were a smaller and less complex mitochondrial network and decreased levels of mitochondrial biogenesis regulators and mitophagy mediators. The approach we used allowed a comprehensive characteristics of elements common for mitochondrial dynamics remodelling accompanying pathogenic mutation. This may be helpful in the deciphering key pathomechanisms of the PD disease.

A future for Ukrainian science.

As the war in Ukraine enters its fourth month, Russian forces continue to destroy the nation's scientific institutions and infrastructure, signaling Russia's intent to obliterate the future for Ukraine. In Kharkiv, for instance, the renowned Institute of Physics and Technology and its newly built Neutron Source nuclear facility have been heavily damaged. Even the Plant Production Institute with its underground national seed bank-one of the world's largest-has been bombed. At the Chernobyl nuclear labs, Russian forces have looted or destroyed hundreds of computers, radiation dosimeters, and irreplaceable software and equipment. Although the response to each international science crisis is necessarily unique, the US National Academy of Sciences is once again joining with international and regional partners to support beleaguered colleagues, as it did last year in the successful extraction and resettlement of Afghanistan scientists at risk from the Taliban. To that end, the national science academies of Poland, Ukraine, and the United States recently convened a meeting of leaders from several national science academies (including the presidents of Germany's Leopoldina science academy, the Royal Danish Academy of Sciences and Letters, and the ALLEA European Federation of Academies of Sciences and Humanities, and leaders from the Royal Society of the United Kingdom) to explore how the global science community can best help Ukraine. The resulting 10-point action plan for the world's research community aims to help meet several immediate needs and also provide the building blocks for revitalizing Ukrainian science in the future.

Effect of Chronic Stress Present in Fibroblasts Derived from Patients with a Sporadic Form of AD on Mitochondrial Function and Mitochondrial Turnover.

Although the sporadic form of Alzheimer's disease (AD) is the prevalent form, the cellular events underlying the disease pathogenesis have not been fully characterized. Accumulating evidence points to mitochondrial dysfunction as one of the events responsible for AD progression. We investigated mitochondrial function in fibroblasts collected from patients diagnosed with the sporadic form of AD (sAD), placing a particular focus on mitochondrial turnover. We measured mitochondrial biogenesis and autophagic clearance, and evaluated the presence of bioenergetic stress in sAD cells. The mitochondrial turnover was clearly lower in the fibroblasts from sAD patients than in the fibroblasts from the control subjects, and the levels of many proteins regulating mitochondrial biogenesis, autophagy and mitophagy were decreased in patient cells. Additionally, the sAD fibroblasts had slightly higher mitochondrial superoxide levels and impaired antioxidant defense. Mitochondrial turnover undergoes feedback regulation through mitochondrial retrograde signaling, which is responsible for the maintenance of optimal mitochondrial functioning, and mitochondria-derived ROS participate as signaling molecules in this process. Our results showed that in sAD patients cells, there is a shift in the balance of mitochondrial function, possibly in response to the presence of cellular stress related to disease development.

Effects of plant alkaloids on mitochondrial bioenergetic parameters.

Mitochondria are among the first responders to various stress factors that challenge cell and tissue homeostasis. Various plant alkaloids have been investigated for their capacity to modulate mitochondrial activities. In this study, we used isolated mitochondria from mouse brain and liver tissues to assess nicotine, anatabine and anabasine, three alkaloids found in tobacco plant, for potential modulatory activity on mitochondrial bioenergetics parameters. All alkaloids decreased basal oxygen consumption of mouse brain mitochondria in a dose-dependent manner without any effect on the ADP-stimulated respiration. None of the alkaloids, at 1 nM or 1.25 µM concentrations, influenced the maximal rate of swelling of brain mitochondria. In contrast to brain mitochondria, 1.25 µM anatabine, anabasine and nicotine increased maximal rate of swelling of liver mitochondria suggesting a toxic effect. Only at 1 mM concentration, anatabine slowed down the maximal rate of Ca2+-induced swelling and increased the time needed to reach the maximal rate of swelling. The observed mitochondrial bioenergetic effects are probably mediated through a pathway independent of nicotinic acetylcholine receptors, as quantitative proteomic analysis could not confirm their expression in pure mitochondrial fractions isolated from mouse brain tissue.

Adaptation of mitochondrial network dynamics and velocity of mitochondrial movement to chronic stress present in fibroblasts derived from patients with sporadic form of Alzheimer's disease.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Only 10% of all cases are familial form, the remaining 90% are sporadic form with unknown genetic background. The etiology of sporadic AD is still not fully understood. Pathogenesis and pathobiology of this disease are limited due to the limited number of experimental models. We used primary culture of fibroblasts derived from patients diagnosed with sporadic form of AD for investigation of dynamic properties of mitochondria, including fission-fusion process and localization of mitochondria within the cell. We observed differences in mitochondrial network organization with decreased mitochondrial transport velocity, and a drop in the frequency of fusion-fission events. These studies show how mitochondrial dynamics adapt to the conditions of long-term mitochondrial stress that prevails in cells of sporadic form of AD.

Alteration of mitochondrial function in the livers of mice with glycogen branching enzyme deficiency.

Glycogen storage disease type IV (GSD IV) is caused by mutations in the glycogen branching enzyme gene (GBE1) that lead to the accumulation of aberrant glycogen in affected tissues, mostly in the liver. To determine whether dysfunctional glycogen metabolism in GSD IV affects other components of cellular bioenergetics, we studied mitochondrial function in heterozygous Gbe1 knockout (Gbe1+/-) mice. Mitochondria isolated from the livers of Gbe1+/- mice showed elevated respiratory complex I activity and increased reactive oxygen species production, particularly by respiratory chain complex III. These observations indicate that GBE1 deficiency leads to broader rearrangements in energy metabolism and that the mechanisms underlying GSD IV pathogenesis may include more than merely mechanical cell damage caused by the presence of glycogen aggregates.

Serum Selenium Level Predicts 10-Year Survival after Breast Cancer.

In a recent prospective study, we reported an association between a low serum selenium level and five-year survival among breast cancer patients. We now have updated the cohort to include 10-year survival rates. A blood sample was obtained from 538 women diagnosed with first primary invasive breast cancer between 2008 and 2015 in the region of Szczecin, Poland. Blood was collected before initiation of treatment. Serum selenium levels were quantified by mass spectroscopy. Each patient was assigned to one of four quartiles based on the distribution of serum selenium levels in the whole cohort. Patients were followed from diagnosis until death or last known alive (mean follow-up 7.9 years). The 10-year actuarial cumulative survival was 65.1% for women in the lowest quartile of serum selenium, compared to 86.7% for women in the highest quartile (p < 0.001 for difference). Further studies are needed to confirm the protective effect of selenium on breast cancer survival. If confirmed this may lead to an investigation of selenium supplementation on survival of breast cancer patients.

Multitasking guardian of mitochondrial quality: Parkin function and Parkinson's disease.

The familial form of Parkinson's disease (PD) is linked to mutations in specific genes. The mutations in parkin are one of the most common causes of early-onset PD. Mitochondrial dysfunction is an emerging active player in the pathology of neurodegenerative diseases, because mitochondria are highly dynamic structures integrated with many cellular functions. Herein, we overview and discuss the role of the parkin protein product, Parkin E3 ubiquitin ligase, in the cellular processes related to mitochondrial function, and how parkin mutations can result in pathology in vitro and in vivo.

Hallmarks of oxidative stress in the livers of aged mice with mild glycogen branching enzyme deficiency.

Glycogen branching enzyme (GBE1) introduces branching points in the glycogen molecule during its synthesis. Pathogenic GBE1 gene mutations lead to glycogen storage disease type IV (GSD IV), which is characterized by excessive intracellular accumulation of abnormal, poorly branched glycogen in affected tissues and organs, mostly in the liver. Using heterozygous Gbe1 knock-out mice (Gbe1+/-), we analyzed the effects of moderate GBE1 deficiency on oxidative stress in the liver. The livers of aged Gbe1+/- mice (22 months old) had decreased GBE1 protein levels, which caused a mild decrease in the degree of glycogen branching, but did not affect the tissue glycogen content. GBE1 deficiency was accompanied by increased protein carbonylation and elevated oxidation of the glutathione pool, indicating the existence of oxidative stress. Furthermore, we have observed increased levels of glutathione peroxidase and decreased activity of respiratory complex I in Gbe1+/- livers. Our data indicate that even mild changes in the degree of glycogen branching, which did not lead to excessive glycogen accumulation, may have broader effects on cellular bioenergetics and redox homeostasis. In young animals cellular homeostatic mechanisms are able to counteract those changes, while in aged tissues the changes may lead to increased oxidative stress.

Nanoscale Viscosity of Cytoplasm Is Conserved in Human Cell Lines.

Metabolic reactions in living cells are limited by diffusion of reagents in the cytoplasm. Any attempt to quantify the kinetics of biochemical reactions in the cytosol should be preceded by careful measurements of the physical properties of the cellular interior. The cytoplasm is a complex, crowded fluid characterized by effective viscosity dependent on its structure at a nanoscopic length scale. In this work, we present and validate the model describing the cytoplasmic nanoviscosity, based on measurements in seven human cell lines, for nanoprobes ranging in diameters from 1 to 150 nm. Irrespective of cell line origin (epithelial-mesenchymal, cancerous-noncancerous, male-female, young-adult), we obtained a similar dependence of the viscosity on the size of the nanoprobes, with characteristic length-scales of 20 ± 11 nm (hydrodynamic radii of major crowders in the cytoplasm) and 4.6 ± 0.7 nm (radii of intercrowder gaps). Moreover, we revealed that the cytoplasm behaves as a liquid for length scales smaller than 100 nm and as a physical gel for larger length scales.

Mitochondrial Network and Biogenesis in Response to Short and Long-Term Exposure of Human BEAS-2B Cells to Aerosol Extracts from the Tobacco Heating System 2.2.

BACKGROUND/AIMS: Adverse effects of cigarette smoke on health are widely known. Heating rather than combusting tobacco is one of strategies to reduce the formation of toxicants. The sensitive nature of mitochondrial dynamics makes the mitochondria an early indicator of cellular stress. For this reason, we studied the morphology and dynamics of the mitochondrial network in human bronchial epithelial cells (BEAS-2B) exposed to total particulate matter (TPM) generated from 3R4F reference cigarette smoke and from aerosol from a new candidate modified risk tobacco product, the Tobacco Heating System (THS 2.2). METHODS: Cells were subjected to short (1 week) and chronic (12 weeks) exposure to a low (7.5 µg/mL) concentration of 3R4F TPM and low (7.5 µg/mL), medium (37.5 µg/mL), and high (150 µg/mL) concentrations of TPM from THS 2.2. Confocal microscopy was applied to assess cellular and mitochondrial morphology. Cytosolic Ca2+ levels, mitochondrial membrane potential and mitochondrial mass were measured with appropriate fluorescent probes on laser scanning cytometer. The levels of proteins regulating mitochondrial dynamics and biogenesis were determined by Western blot. RESULTS: In BEAS-2B cells exposed for one week to the low concentration of 3R4F TPM and the high concentration of THS 2.2 TPM we observed clear changes in cell morphology, mitochondrial network fragmentation, altered levels of mitochondrial fusion and fission proteins and decreased biogenesis markers. Also cellular proliferation was slowed down. Upon chronic exposure (12 weeks) many parameters were affected in the opposite way comparing to short exposure. We observed strong increase of NRF2 protein level, reorganization of mitochondrial network and activation of the mitochondrial biogenesis process. CONCLUSION: Comparison of the effects of TPMs from 3R4F and from THS 2.2 revealed, that similar extent of alterations in mitochondrial dynamics and biogenesis is observed at 7.5 µg/mL of 3R4F TPM and 150 µg/mL of THS 2.2 TPM. 7 days exposure to the investigated components of cigarette smoke evoke mitochondrial stress, while upon chronic, 12 weeks exposure the hallmarks of cellular adaptation to the stressor were visible. The results also suggest that mitochondrial stress signaling is involved in the process of cellular adaptation under conditions of chronic stress caused by 3R4F and high concentration of THS 2.2.

Mitochondria as a possible target for nicotine action.

Mitochondria are multifunctional and dynamic organelles deeply integrated into cellular physiology and metabolism. Disturbances in mitochondrial function are involved in several disorders such as neurodegeneration, cardiovascular diseases, metabolic diseases, and also in the aging process. Nicotine is a natural alkaloid present in the tobacco plant which has been well studied as a constituent of cigarette smoke. It has also been reported to influence mitochondrial function both in vitro and in vivo. This review presents a comprehensive overview of the present knowledge of nicotine action on mitochondrial function. Observed effects of nicotine exposure on the mitochondrial respiratory chain, oxidative stress, calcium homeostasis, mitochondrial dynamics, biogenesis, and mitophagy are discussed, considering the context of the experimental design. The potential action of nicotine on cellular adaptation and cell survival is also examined through its interaction with mitochondria. Although a large number of studies have demonstrated the impact of nicotine on various mitochondrial activities, elucidating its mechanism of action requires further investigation.

Determination of oligomerization state of Drp1 protein in living cells at nanomolar concentrations.

Biochemistry in living cells is an emerging field of science. Current quantitative bioassays are performed ex vivo, thus equilibrium constants and reaction rates of reactions occurring in human cells are still unknown. To address this issue, we present a non-invasive method to quantitatively characterize interactions (equilibrium constants, KD) directly within the cytosol of living cells. We reveal that cytosolic hydrodynamic drag depends exponentially on a probe's size, and provide a model for its determination for different protein sizes (1-70 nm). We analysed oligomerization of dynamin-related protein 1 (Drp1, wild type and mutants: K668E, G363D, C505A) in HeLa cells. We detected the coexistence of wt-Drp1 dimers and tetramers in cytosol, and determined that KD for tetramers was 0.7 ± 0.5 µM. Drp1 kinetics was modelled by independent simulations, giving computational results which matched experimental data. This robust method can be applied to in vivo determination of KD for other protein-protein complexes, or drug-target interactions.

Distinction of sporadic and familial forms of ALS based on mitochondrial characteristics.

Bioenergetic failure, oxidative stress, and changes in mitochondrial morphology are common pathologic hallmarks of amyotrophic lateral sclerosis (ALS) in several cellular and animal models. Disturbed mitochondrial physiology has serious consequences for proper functioning of the cell, leading to the chronic mitochondrial stress. Mitochondria, being in the center of cellular metabolism, play a pivotal role in adaptation to stress conditions. We found that mitochondrial dysfunction and adaptation processes differ in primary fibroblasts derived from patients diagnosed with either sporadic or familial forms of ALS. The evaluation of mitochondrial parameters such as the mitochondrial membrane potential, the oxygen consumption rate, the activity and levels of respiratory chain complexes, and the levels of ATP, reactive oxygen species, and Ca2+ show that the bioenergetic properties of mitochondria are different in sporadic ALS, familial ALS, and control groups. Comparative statistical analysis of the data set (with use of principal component analysis and support vector machine) identifies and distinguishes 3 separate groups despite the small number of investigated cell lines and high variability in measured parameters. These findings could be a first step in development of a new tool for predicting sporadic and familial forms of ALS and could contribute to knowledge of its pathophysiology.-Walczak, J., Debska-Vielhaber, G., Vielhaber, S., Szymanski, J., Charzynska, A., Duszynski, J., Szczepanowska, J. Distinction of sporadic and familial forms of ALS based on mitochondrial characteristics.

Mitochondria and Reactive Oxygen Species in Aging and Age-Related Diseases.

Aging has been linked to several degenerative processes that, through the accumulation of molecular and cellular damage, can progressively lead to cell dysfunction and organ failure. Human aging is linked with a higher risk for individuals to develop cancer, neurodegenerative, cardiovascular, and metabolic disorders. The understanding of the molecular basis of aging and associated diseases has been one major challenge of scientific research over the last decades. Mitochondria, the center of oxidative metabolism and principal site of reactive oxygen species (ROS) production, are crucial both in health and in pathogenesis of many diseases. Redox signaling is important for the modulation of cell functions and several studies indicate a dual role for ROS in cell physiology. In fact, high concentrations of ROS are pathogenic and can cause severe damage to cell and organelle membranes, DNA, and proteins. On the other hand, moderate amounts of ROS are essential for the maintenance of several biological processes, including gene expression. In this review, we provide an update regarding the key roles of ROS-mitochondria cross talk in different fundamental physiological or pathological situations accompanying aging and highlighting that mitochondrial ROS may be a decisive target in clinical practice.

Relation Between Mitochondrial Membrane Potential and ROS Formation.

Mitochondria are considered the main source of reactive oxygen species (ROS) in the cell. For this reason they have been recognized as a source of various pathological conditions as well as aging. Chronic increase in the rate of ROS production is responsible for the accumulation of ROS-associated damages in DNA, proteins, and lipids and may result in progressive cell dysfunctions and, in a consequence, apoptosis, increasing the overall probability of an organism's pathological conditions. The superoxide anion is the main undesired by-product of mitochondrial oxidative phosphorylation. Its production is triggered by a leak of electrons from the mitochondrial respiratory chain and the reaction of these electrons with O2. Superoxide dismutase (MnSOD, SOD2) from the mitochondrial matrix, as well as superoxide dismutase (Cu/ZnSOD, SOD1) present in small amounts in the mitochondrial intramembrane space, converts superoxide anion to hydrogen peroxide, which can be then converted by catalase to harmless H2O.In the chapter we describe a relation between mitochondrial membrane potential and the rate of ROS formation. We present different methods applicable for isolated mitochondria or intact cells. We also present experiments demonstrating that a magnitude and a direction (increase or decrease) of a change in mitochondrial ROS production depend on the metabolic state of this organelle.

Insight into the fission mechanism by quantitative characterization of Drp1 protein distribution in the living cell.

One of the main players in the process of mitochondrial fragmentation is dynamin-related protein 1 (Drp1), which assembles into a helical ring-like structure on the mitochondria and facilitates fission. The fission mechanism is still poorly understood and detailed information concerning oligomeric form of Drp1, its cellular distribution and the size of the fission complex is missing. To estimate oligomeric forms of Drp1 in the cytoplasm and on the mitochondria, we performed a quantitative analysis of Drp1 diffusion and distribution in gene-edited HeLa cell lines. This paper provides an insight into the fission mechanism based on the quantitative description of Drp1 cellular distribution. We found that approximately half of the endogenous GFP-Drp1 pool remained in the cytoplasm, predominantly in a tetrameric form, at a concentration of 28 ± 9 nM. The Drp1 mitochondrial pool included many different oligomeric states with equilibrium distributions that could be described by isodesmic supramolecular polymerization with a Kd of 31 ± 10 nM. We estimated the average number of Drp1 molecules forming the functional fission complex to be approximately 100, representing not more than 14% of all Drp1 oligomers. We showed that the upregulated fission induced by niclosamide is accompanied by an increase in the number of large Drp1 oligomers.

Mitochondria-associated membranes in aging and senescence: structure, function, and dynamics.

Sites of close contact between mitochondria and the endoplasmic reticulum (ER) are known as mitochondria-associated membranes (MAM) or mitochondria-ER contacts (MERCs), and play an important role in both cell physiology and pathology. A growing body of evidence indicates that changes observed in the molecular composition of MAM and in the number of MERCs predisposes MAM to be considered a dynamic structure. Its involvement in processes such as lipid biosynthesis and trafficking, calcium homeostasis, reactive oxygen species production, and autophagy has been experimentally confirmed. Recently, MAM have also been studied in the context of different pathologies, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, type 2 diabetes mellitus and GM1-gangliosidosis. An underappreciated amount of data links MAM with aging or senescence processes. In the present review, we summarize the current knowledge of basic MAM biology, composition and action, and discuss the potential connections supporting the idea that MAM are significant players in longevity.