Small fibre neuropathy in Fabry disease: a human-derived neuronal in vitro disease model and pilot data

Acral burning pain triggered by fever, thermal hyposensitivity and skin denervation are hallmarks of small fibre neuropathy in Fabry disease, a life-threatening X-linked lysosomal storage disorder. Variants in the gene encoding alpha-galactosidase A may lead to impaired enzyme activity with cellular accumulation of globotriaosylceramide. To study the underlying pathomechanism of Fabry-associated small fibre neuropathy, we generated a neuronal in vitro disease model using patient-derived induced pluripotent stem cells from three Fabry patients and one healthy control. We further generated an isogenic control line via gene editing. We subjected induced pluripotent stem cells to targeted peripheral neuronal differentiation and observed intra-lysosomal globotriaosylceramide accumulations in somas and neurites of Fabry sensory neurons using super-resolution microscopy. At functional level, patch-clamp analysis revealed a hyperpolarizing shift of voltage-gated sodium channel steady-state inactivation kinetics in isogenic control neurons compared with healthy control neurons (P < 0.001). Moreover, we demonstrate a drastic increase in Fabry sensory neuron calcium levels at 39°C mimicking clinical fever (P < 0.001). This pathophysiological phenotype was accompanied by thinning of neurite calibres in sensory neurons differentiated from induced pluripotent stem cells derived from Fabry patients compared with healthy control cells (P < 0.001). Linear-nonlinear cascade models fit to spiking responses revealed that Fabry cell lines exhibit altered single neuron encoding properties relative to control. We further observed mitochondrial aggregation at sphingolipid accumulations within Fabry sensory neurites utilizing a click chemistry approach together with mitochondrial dysmorphism compared with healthy control cells. We pioneer pilot insights into the cellular mechanisms contributing to pain, thermal hyposensitivity and denervation in Fabry small fibre neuropathy and pave the way for further mechanistic in vitro studies in Fabry disease and the development of novel treatment approaches.

Fabry Disease: Cardiac Implications and Molecular Mechanisms

PURPOSE OF REVIEW

This review explores the interplay among metabolic dysfunction, oxidative stress, inflammation, and fibrosis in Fabry disease, focusing on their potential implications for cardiac involvement. We aim to discuss the biochemical processes that operate in parallel to sphingolipid accumulation and contribute to disease pathogenesis, emphasizing the importance of a comprehensive understanding of these processes.

RECENT FINDINGS

Beyond sphingolipid accumulation, emerging studies have revealed that mitochondrial dysfunction, oxidative stress, and chronic inflammation could be significant contributors to Fabry disease and cardiac involvement. These factors promote cardiac remodeling and fibrosis and may predispose Fabry patients to conduction disturbances, ventricular arrhythmias, and heart failure. While current treatments, such as enzyme replacement therapy and pharmacological chaperones, address disease progression and symptoms, their effectiveness is limited. Our review uncovers the potential relationships among metabolic disturbances, oxidative stress, inflammation, and fibrosis in Fabry disease-related cardiac complications. Current findings suggest that beyond sphingolipid accumulation, other mechanisms may significantly contribute to disease pathogenesis. This prompts the exploration of innovative therapeutic strategies and underscores the importance of a holistic approach to understanding and managing Fabry disease.

Mutations in DNAJC19 cause altered mitochondrial structure and increased mitochondrial respiration in human iPSC-derived cardiomyocytes

BACKGROUND

Dilated cardiomyopathy with ataxia (DCMA) is an autosomal recessive disorder arising from truncating mutations in DNAJC19, which encodes an inner mitochondrial membrane protein. Clinical features include an early onset, often life-threatening, cardiomyopathy associated with other metabolic features. Here, we aim to understand the metabolic and pathophysiological mechanisms of mutant DNAJC19 for the development of cardiomyopathy.

METHODS

We generated induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) of two affected siblings with DCMA and a gene-edited truncation variant (tv) of DNAJC19 which all lack the conserved DnaJ interaction domain. The mutant iPSC-CMs and their respective control cells were subjected to various analyses, including assessments of morphology, metabolic function, and physiological consequences such as Ca2+ kinetics, contractility, and arrhythmic potential. Validation of respiration analysis was done in a gene-edited HeLa cell line (DNAJC19tvHeLa).

RESULTS

Structural analyses revealed mitochondrial fragmentation and abnormal cristae formation associated with an overall reduced mitochondrial protein expression in mutant iPSC-CMs. Morphological alterations were associated with higher oxygen consumption rates (OCRs) in all three mutant iPSC-CMs, indicating higher electron transport chain activity to meet cellular ATP demands. Additionally, increased extracellular acidification rates suggested an increase in overall metabolic flux, while radioactive tracer uptake studies revealed decreased fatty acid uptake and utilization of glucose. Mutant iPSC-CMs also showed increased reactive oxygen species (ROS) and an elevated mitochondrial membrane potential. Increased mitochondrial respiration with pyruvate and malate as substrates was observed in mutant DNAJC19tv HeLa cells in addition to an upregulation of respiratory chain complexes, while cellular ATP-levels remain the same. Moreover, mitochondrial alterations were associated with increased beating frequencies, elevated diastolic Ca2+ concentrations, reduced sarcomere shortening and an increased beat-to-beat rate variability in mutant cell lines in response to β-adrenergic stimulation.

CONCLUSIONS

Loss of the DnaJ domain disturbs cardiac mitochondrial structure with abnormal cristae formation and leads to mitochondrial dysfunction, suggesting that DNAJC19 plays an essential role in mitochondrial morphogenesis and biogenesis. Moreover, increased mitochondrial respiration, altered substrate utilization, increased ROS production and abnormal Ca2+ kinetics provide insights into the pathogenesis of DCMA-related cardiomyopathy.

An interferon gamma response signature links myocardial aging and immunosenescence

AIMS

Aging entails profound immunological transformations that can impact myocardial homeostasis and predispose to heart failure. However, preclinical research in the immune-cardiology field is mostly conducted in young healthy animals, which potentially weakens its translational relevance. Herein, we sought to investigate how the aging T-cell compartment associates with changes in myocardial cell biology in aged mice.

METHODS AND RESULTS

We phenotyped the antigen-experienced effector/memory T cells purified from heart-draining lymph nodes of 2-, 6-, 12-, and 18-month-old C57BL/6J mice using single-cell RNA/T cell receptor sequencing. Simultaneously, we profiled all non-cardiomyocyte cell subsets purified from 2- to 18-month-old hearts and integrated our data with publicly available cardiomyocyte single-cell sequencing datasets. Some of these findings were confirmed at the protein level by flow cytometry. With aging, the heart-draining lymph node and myocardial T cells underwent clonal expansion and exhibited an up-regulated pro-inflammatory transcription signature, marked by an increased interferon-γ (IFN-γ) production. In parallel, all major myocardial cell populations showed increased IFN-γ responsive signature with aging. In the aged cardiomyocytes, a stronger IFN-γ response signature was paralleled by the dampening of expression levels of transcripts related to most metabolic pathways, especially oxidative phosphorylation. Likewise, induced pluripotent stem cells-derived cardiomyocytes exposed to chronic, low grade IFN-γ treatment showed a similar inhibition of metabolic activity.

CONCLUSIONS

By investigating the paired age-related alterations in the T cells found in the heart and its draining lymph nodes, we provide evidence for increased myocardial IFN-γ signaling with age, which is associated with inflammatory and metabolic shifts typically seen in heart failure.

Activation of the integrated stress response rewires cardiac metabolism in Barth syndrome

Barth Syndrome (BTHS) is an inherited cardiomyopathy caused by defects in the mitochondrial transacylase TAFAZZIN (Taz), required for the synthesis of the phospholipid cardiolipin. BTHS is characterized by heart failure, increased propensity for arrhythmias and a blunted inotropic reserve. Defects in Ca2+-induced Krebs cycle activation contribute to these functional defects, but despite oxidation of pyridine nucleotides, no oxidative stress developed in the heart. Here, we investigated how retrograde signaling pathways orchestrate metabolic rewiring to compensate for mitochondrial defects. In mice with an inducible knockdown (KD) of TAFAZZIN, and in induced pluripotent stem cell-derived cardiac myocytes, mitochondrial uptake and oxidation of fatty acids was strongly decreased, while glucose uptake was increased. Unbiased transcriptomic analyses revealed that the activation of the eIF2α/ATF4 axis of the integrated stress response upregulates one-carbon metabolism, which diverts glycolytic intermediates towards the biosynthesis of serine and fuels the biosynthesis of glutathione. In addition, strong upregulation of the glutamate/cystine antiporter xCT increases cardiac cystine import required for glutathione synthesis. Increased glutamate uptake facilitates anaplerotic replenishment of the Krebs cycle, sustaining energy production and antioxidative pathways. These data indicate that ATF4-driven rewiring of metabolism compensates for defects in mitochondrial uptake of fatty acids to sustain energy production and antioxidation.

Mitochondrial dysfunction promotes the transition of precursor to terminally exhausted T cells through HIF-1α-mediated glycolytic reprogramming

T cell exhaustion is a hallmark of cancer and persistent infections, marked by inhibitory receptor upregulation, diminished cytokine secretion, and impaired cytolytic activity. Terminally exhausted T cells are steadily replenished by a precursor population (Tpex), but the metabolic principles governing Tpex maintenance and the regulatory circuits that control their exhaustion remain incompletely understood. Using a combination of gene-deficient mice, single-cell transcriptomics, and metabolomic analyses, we show that mitochondrial insufficiency is a cell-intrinsic trigger that initiates the functional exhaustion of T cells. At the molecular level, we find that mitochondrial dysfunction causes redox stress, which inhibits the proteasomal degradation of hypoxia-inducible factor 1α (HIF-1α) and promotes the transcriptional and metabolic reprogramming of Tpex cells into terminally exhausted T cells. Our findings also bear clinical significance, as metabolic engineering of chimeric antigen receptor (CAR) T cells is a promising strategy to enhance the stemness and functionality of Tpex cells for cancer immunotherapy.

Metabolic switch from fatty acid oxidation to glycolysis in knock-in mouse model of Barth syndrome

Mitochondria are central for cellular metabolism and energy supply. Barth syndrome (BTHS) is a severe disorder, due to dysfunction of the mitochondrial cardiolipin acyl transferase tafazzin. Altered cardiolipin remodeling affects mitochondrial inner membrane organization and function of membrane proteins such as transporters and the oxidative phosphorylation (OXPHOS) system. Here, we describe a mouse model that carries a G197V exchange in tafazzin, corresponding to BTHS patients. TAZG197V mice recapitulate disease-specific pathology including cardiac dysfunction and reduced oxidative phosphorylation. We show that mutant mitochondria display defective fatty acid-driven oxidative phosphorylation due to reduced levels of carnitine palmitoyl transferases. A metabolic switch in ATP production from OXPHOS to glycolysis is apparent in mouse heart and patient iPSC cell-derived cardiomyocytes. An increase in glycolytic ATP production inactivates AMPK causing altered metabolic signaling in TAZG197V . Treatment of mutant cells with AMPK activator reestablishes fatty acid-driven OXPHOS and protects mice against cardiac dysfunction.

Metal hypersensitivity in hip, knee and spine surgery

The number of implanted joint prostheses and damaged spinal components is steadily increasing. At the same time, rejection of the implanted material is observed in operated patients, which manifests itself in both skin and general reactions, as well as loosening and earlier wear of implanted prostheses, which was previously referred to as aseptic reactions. However, it has been shown that in a significant proportion of patients, rejection of implanted material may be caused by hypersensitivity to a specific metal. For this reason, patients qualified for implantation of foreign material, mainly nickel, titanium, chromium, molybdenum, and other alloys, should be subjected to allergy tests to detect possible risks in the form of metal sensitivity reactions.

Cardiac Involvement in Mitochondrial Disorders

PURPOSE OF REVIEW

We review pathophysiology and clinical features of mitochondrial disorders manifesting with cardiomyopathy.

RECENT FINDINGS

Mechanistic studies have shed light into the underpinnings of mitochondrial disorders, providing novel insights into mitochondrial physiology and identifying new therapeutic targets. Mitochondrial disorders are a group of rare genetic diseases that are caused by mutations in mitochondrial DNA (mtDNA) or in nuclear genes that are essential to mitochondrial function. The clinical picture is extremely heterogeneous, the onset can occur at any age, and virtually, any organ or tissue can be involved. Since the heart relies primarily on mitochondrial oxidative metabolism to fuel contraction and relaxation, cardiac involvement is common in mitochondrial disorders and often represents a major determinant of their prognosis.

[Is aseptic loosening of joint prostheses aseptic?]

The observed changes in the periarticular space may be caused by both mechanical action and biological reactions. Periprosthetic infections are the most common cause of loosening and destructive changes in the joints, however, the diagnosis of an aseptic reaction is not always fully obvious. Micromovements between the implant and the surrounding bone can cause remodeling of the bone trabeculae and migration of fibroblasts into the voids between the implant surface and the bone. In addition, repetitive stresses can induce fibroblast proliferation. On the other hand, the residues arising from the wear of implanted materials in the joints may play an important role in the process of loosening of prostheses - both aseptic and septic. Direct interactions between the released molecule and the macrophage surface are sufficient to activate osteoclastogenic signaling pathways. You cannot ignore allergic reactions to metals used in prostheses in patients undergoing arthroplasty. Demonstration of hypersensitivity to the components of dentures in some cases requires the use of appropriate material in order not to cause an inflammatory allergic reaction. Emerging treatment strategies using mesenchymal stem cells (MSCs) are aimed at improving the initial implant integration and preventing periprosthetic osteolysis. It should be emphasized, however, that the diagnosis of aseptic loosening in many clinical situations raises doubts, because it is at the root of everyone.

Analysis of mortality between 2019-2020 at the Neuroorthopedic and Traumatic Orthopedic Departments

The number of deaths from skeletal injuries is still significant, but is declining with advances in emergency medicine. The adopted principles of emergency procedures and the availability of specialist centres enable the treatment to be effective.

AIM

The aim of the study was to analyse the deaths of patients with spine and limb injuries who required surgery.

MATERIALS AND METHODS

The analysis covered 22 deaths in the years 2019-2020. The assessment took into account: the cause of admission, the condition of the patient and comorbidities, the medical scales which were used to assess the possible risk of complications, the diagnostic correctness and qualification for surgical treatment, the waiting time for surgery and the cause of death and prior course of action.

RESULTS

It can be stated that in 2019, the mortality rate was 0.21 (10 deaths out of 4658 hospitalized), in 2020, the mortality rate was 0.31 (12 deaths out of 3852 hospitalized). The mortality rate in the Department of Traumatic Orthopedics was: 0.30 in 2019 (8 deaths out of 2625 hospitalized) and 0.39 in 2020 (8 deaths in 2020 hospitalized). 10 patients with hip fractures (trochanteric and femoral neck) underwent surgery within 2.7 days (from 1 to 4 days). The causes of death within 1-9 days (average 4.86 days) from admission in this group were complex, and associated with the presence of chronic diseases, including: circulatory failure (9), septic shock (1), heart rhythm disturbances (7), renal failure (6), pulmonary congestion (4), hyperkalemia (1), coagulation disorders (1). In patients after spinal injury with quadriplegia, decompression (1), stabilization (1) and disc removal (1) were performed on the day of admission to the hospital. The patients were hospitalized in the ICU, and deaths occurred on days 9, 15 and 187 from admission due to respiratory and circulatory failure and sudden cardiac arrest. Patients after arthroplasty of the knee (1) and hip (2) were operated on day 2 from admission, and deaths occurred on day 4, 22 and 53 due to: sepsis (1), pulmonary embolism (1), respiratory failure in the course of pneumonia (1).

CONCLUSIONS

The deceased were admitted in a serious general condition, burdened with numerous concomitant chronic diseases and their age ranged from 66 to 97 years. The surgical treatment was undertaken for life saving reasons but 5 of the deceased did not undergo surgery due to the extreme general condition leading to respiratory and circulatory failure.

Genetic Ablation of the Mitochondrial Calcium Uniporter (MCU) Does not Impair T Cell-Mediated Immunity In Vivo

T cell activation and differentiation is associated with metabolic reprogramming to cope with the increased bioenergetic demand and to provide metabolic intermediates for the biosynthesis of building blocks. Antigen receptor stimulation not only promotes the metabolic switch of lymphocytes but also triggers the uptake of calcium (Ca²⁺) from the cytosol into the mitochondrial matrix. Whether mitochondrial Ca²⁺ influx through the mitochondrial Ca²⁺ uniporter (MCU) controls T cell metabolism and effector function remained, however, enigmatic. Using mice with T cell-specific deletion of MCU, we here show that genetic inactivation of mitochondrial Ca²⁺ uptake increased cytosolic Ca²⁺ levels following antigen receptor stimulation and store-operated Ca²⁺ entry (SOCE). However, ablation of MCU and the elevation of cytosolic Ca²⁺ did not affect mitochondrial respiration, differentiation and effector function of inflammatory and regulatory T cell subsets in vitro and in animal models of T cell-mediated autoimmunity and viral infection. These data suggest that MCU-mediated mitochondrial Ca²⁺ uptake is largely dispensable for murine T cell function. Our study has also important technical implications. Previous studies relied mostly on pharmacological inhibition or transient knockdown of mitochondrial Ca²⁺ uptake, but our results using mice with genetic deletion of MCU did not recapitulate these findings. The discrepancy of our study to previous reports hint at compensatory mechanisms in MCU-deficient mice and/or off-target effects of current MCU inhibitors.

Mechano-energetic aspects of Barth syndrome

Energy-demanding organs like the heart are strongly dependent on oxidative phosphorylation in mitochondria. Oxidative phosphorylation is governed by the respiratory chain located in the inner mitochondrial membrane. The inner mitochondrial membrane is the only cellular membrane with significant amounts of the phospholipid cardiolipin, and cardiolipin was found to directly interact with a number of essential protein complexes, including respiratory chain complexes I to V. An inherited defect in the biogenesis of cardiolipin causes Barth syndrome, which is associated with cardiomyopathy, skeletal myopathy, neutropenia and growth retardation. Energy conversion is dependent on reducing equivalents, which are replenished by oxidative metabolism in the Krebs cycle. Cardiolipin deficiency in Barth syndrome also affects Krebs cycle activity, metabolite transport and mitochondrial morphology. During excitation-contraction coupling, calcium (Ca²⁺ ) released from the sarcoplasmic reticulum drives sarcomeric contraction. At the same time, Ca²⁺ influx into mitochondria drives the activation of Krebs cycle dehydrogenases and the regeneration of reducing equivalents. Reducing equivalents are essential not only for energy conversion, but also for maintaining a redox buffer, which is required to detoxify reactive oxygen species (ROS). Defects in CL may also affect Ca²⁺ uptake into mitochondria and thereby hamper energy supply and demand matching, but also detoxification of ROS. Here, we review the impact of cardiolipin deficiency on mitochondrial function in Barth syndrome and discuss potential therapeutic strategies.

Loss of Mitochondrial Ca2+ Uniporter Limits Inotropic Reserve and Provides Trigger and Substrate for Arrhythmias in Barth Syndrome Cardiomyopathy

BACKGROUND

Barth syndrome (BTHS) is caused by mutations of the gene encoding tafazzin, which catalyzes maturation of mitochondrial cardiolipin and often manifests with systolic dysfunction during early infancy. Beyond the first months of life, BTHS cardiomyopathy typically transitions to a phenotype of diastolic dysfunction with preserved ejection fraction, blunted contractile reserve during exercise, and arrhythmic vulnerability. Previous studies traced BTHS cardiomyopathy to mitochondrial formation of reactive oxygen species (ROS). Because mitochondrial function and ROS formation are regulated by excitation-contraction coupling, integrated analysis of mechano-energetic coupling is required to delineate the pathomechanisms of BTHS cardiomyopathy.

METHODS

We analyzed cardiac function and structure in a mouse model with global knockdown of tafazzin (Taz-KD) compared with wild-type littermates. Respiratory chain assembly and function, ROS emission, and Ca²⁺ uptake were determined in isolated mitochondria. Excitation-contraction coupling was integrated with mitochondrial redox state, ROS, and Ca²⁺ uptake in isolated, unloaded or preloaded cardiac myocytes, and cardiac hemodynamics analyzed in vivo.

RESULTS

Taz-KD mice develop heart failure with preserved ejection fraction (>50%) and age-dependent progression of diastolic dysfunction in the absence of fibrosis. Increased myofilament Ca²⁺ affinity and slowed cross-bridge cycling caused diastolic dysfunction, in part, compensated by accelerated diastolic Ca²⁺ decay through preactivated sarcoplasmic reticulum Ca²⁺-ATPase. Taz deficiency provoked heart-specific loss of mitochondrial Ca²⁺ uniporter protein that prevented Ca²⁺-induced activation of the Krebs cycle during β-adrenergic stimulation, oxidizing pyridine nucleotides and triggering arrhythmias in cardiac myocytes. In vivo, Taz-KD mice displayed prolonged QRS duration as a substrate for arrhythmias, and a lack of inotropic response to β-adrenergic stimulation. Cellular arrhythmias and QRS prolongation, but not the defective inotropic reserve, were restored by inhibiting Ca²⁺ export through the mitochondrial Na⁺/Ca²⁺ exchanger. All alterations occurred in the absence of excess mitochondrial ROS in vitro or in vivo.

CONCLUSIONS

Downregulation of mitochondrial Ca²⁺ uniporter, increased myofilament Ca²⁺ affinity, and preactivated sarcoplasmic reticulum Ca²⁺-ATPase provoke mechano-energetic uncoupling that explains diastolic dysfunction and the lack of inotropic reserve in BTHS cardiomyopathy. Furthermore, defective mitochondrial Ca²⁺ uptake provides a trigger and a substrate for ventricular arrhythmias. These insights can guide the ongoing search for a cure of this orphaned disease.

Metabolic and Redox Regulation of Cardiovascular Stem Cell Biology and Pathology

Significance: Cardiovascular stem cells are important for regeneration and repair of damaged tissue. Recent Advances: Pluripotent stem cells have a unique metabolism, which is adopted for their energetic and biosynthetic demand as rapidly proliferating cells. Stem cell differentiation requires an exceptional metabolic flexibility allowing for metabolic remodeling between glycolysis and oxidative phosphorylation. Critical Issues: Respiration is associated with the generation of reactive oxygen species (ROS) by the mitochondrial respiratory chain. But also the membrane-bound protein nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase, NOX) contributes to ROS levels. ROS not only play a significant role in stem cell differentiation and tissue renewal but also cause senescence and contribute to tissue aging. Future Directions: For utilization of stem cells in therapeutic approaches, a deep understanding of the molecular mechanisms how metabolism and the cellular redox state regulate stem cell differentiation is required. Modulating the redox state of stem cells using antioxidative agents may be suitable to enhance activity of endothelial progenitor cells. Antioxid. Redox Signal. 35, 163-181.

Effects of Octenidine on the Formation and Disruption of Dental Biofilms: An Exploratory In Situ Study in Healthy Subjects

Dental biofilms are highly structured, complex multispecies communities that, if left untreated, lead to severe oral complications such as caries and periodontal diseases. Therefore, antibiofilm agents are often recommended for both preventive and therapeutic measures. However, biofilm management can be challenging due to the low sensitivity of biofilms to antimicrobial treatments. Octenidine dihydrochloride (OCT) is a highly effective antibacterial agent. Because the OCT antibiofilm efficacy has not been studied in situ, this exploratory crossover study aimed to evaluate the effects of OCT mouth rinsing on biofilm formation and on the disruption of mature biofilms. Moreover, a comparison to the gold-standard chlorhexidine (CHX) was conducted. The biofilms were formed intraorally by 5 healthy volunteers on enamel specimens fixed to acrylic splints. For biofilm formation analysis, OCT, CHX, or water rinses were applied for 30 s every 12 h. The samples evaluation took place at 24-and 48-h time points. For biofilm disruption analysis, sample assessment was performed before and directly after the first OCT or CHX rinse on 48-h mature biofilms. A second rinse was carried out 12 h later. The last assessment was applied to 72-h mature biofilms. The biofilms were analyzed by fluorescence microscopy and transmission electron microscopy. The results showed OCT significantly reducing biofilm formation and bacterial vitality in situ. Simultaneously, the biofilm thickness was strongly decreased. Moreover, a single application of OCT to a 48-h mature biofilm induced substantial biofilm disruption. In addition, the efficacy of OCT compared favorably to CHX. These findings show that OCT rinses prevent biofilm formation and disrupt preexisting mature biofilms formed by healthy subjects. This work suggests that OCT might be used for dental biofilm management as a part of the medical treatment of oral diseases. Future studies with a larger subject heterogeneity and number are needed to confirm the observed OCT effects.

Immuno-metabolic interfaces in cardiac disease and failure

The interplay between the cardiovascular system, metabolism, and inflammation plays a central role in the pathophysiology of a wide spectrum of cardiovascular diseases, including heart failure. Here, we provide an overview of the fundamental aspects of the interrelation between inflammation and metabolism, ranging from the role of metabolism in immune cell function to the processes how inflammation modulates systemic and cardiac metabolism. Furthermore, we discuss how disruption of this immuno-metabolic interface is involved in the development and progression of cardiovascular disease, with a special focus on heart failure. Finally, we present new technologies and therapeutic approaches that have recently emerged and hold promise for the future of cardiovascular medicine.

Ketogenic diet as a potential intervention for lipedema

Lipedema (LI) is a common yet misdiagnosed condition, often misconstrued with obesity. LI affects women almost exclusively, and its painful and life-changing symptoms have long been thought to be resistant to the lifestyle interventions such as diet and exercise. In this paper, we discuss possible mechanisms by which patients adopting a ketogenic diet (KD) can alleviate many of the unwanted clinical features of LI. This paper is also an effort to provide evidence for the hypothesis of the potency of this dietary intervention for addressing the symptoms of LI. Specifically, we examine the scientific evidence of effectiveness of adopting a KD by patients to alleviate clinical features associated with LI, including excessive and disproportionate lower body adipose tissue (AT) deposition, pain, and reduction in quality of life (QoL). We also explore several clinical features of LI currently under debate, including the potential existence and nature of edema, metabolic and hormonal dysfunction, inflammation, and fibrosis. The effectiveness of a KD on addressing clinical features of LI has been demonstrated in human studies, and shows promise as an intervention for LI. We hope this paper leads to an improved understanding of optimal nutritional management for patients with LI and stimulates future research in this area of study.

Cardiolipin remodeling in Barth syndrome and other hereditary cardiomyopathies

Mitochondria play a prominent role in cardiac energy metabolism, and their function is critically dependent on the integrity of mitochondrial membranes. Disorders characterized by mitochondrial dysfunction are commonly associated with cardiac disease. The mitochondrial phospholipid cardiolipin directly interacts with a number of essential protein complexes in the mitochondrial membranes including the respiratory chain, mitochondrial metabolite carriers, and proteins critical for mitochondrial morphology. Barth syndrome is an X-linked disorder caused by an inherited defect in the biogenesis of the mitochondrial phospholipid cardiolipin. How cardiolipin deficiency impacts on mitochondrial function and how mitochondrial dysfunction causes cardiomyopathy has been intensively studied in cellular and animal models of Barth syndrome. These findings may also have implications for the molecular mechanisms underlying other inherited disorders associated with defects in cardiolipin, such as Sengers syndrome and dilated cardiomyopathy with ataxia (DCMA).

Defective Mitochondrial Cardiolipin Remodeling Dampens HIF-1α Expression in Hypoxia

Mitochondria fulfill vital metabolic functions and act as crucial cellular signaling hubs, integrating their metabolic status into the cellular context. Here, we show that defective cardiolipin remodeling, upon loss of the cardiolipin acyl transferase tafazzin, decreases HIF-1α signaling in hypoxia. Tafazzin deficiency does not affect posttranslational HIF-1α regulation but rather HIF-1α gene expression, a dysfunction recapitulated in iPSC-derived cardiomyocytes from Barth syndrome patients with tafazzin deficiency. RNA-seq analyses confirmed drastically altered signaling in tafazzin mutant cells. In hypoxia, tafazzin-deficient cells display reduced production of reactive oxygen species (ROS) perturbing NF-κB activation and concomitantly HIF-1α gene expression. Tafazzin-deficient mice hearts display reduced HIF-1α levels and undergo maladaptive hypertrophy with heart failure in response to pressure overload challenge. We conclude that defective mitochondrial cardiolipin remodeling dampens HIF-1α signaling due to a lack of NF-κB activation through reduced mitochondrial ROS production, decreasing HIF-1α transcription.

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Defective remodeling of mitochondrial cardiolipin dampens HIF-1α signaling

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ROS-mediated NF-κB activation is impaired in cardiolipin-deficient cells

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Defective NF-κB-mediated HIF-1α gene induction decreases the cellular response to hypoxia

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Deregulated cardiac response to pressure overload in Barth syndrome mouse

Metabolic Alterations in Inherited Cardiomyopathies

The normal function of the heart relies on a series of complex metabolic processes orchestrating the proper generation and use of energy. In this context, mitochondria serve a crucial role as a platform for energy transduction by supplying ATP to the varying demand of cardiomyocytes, involving an intricate network of pathways regulating the metabolic flux of substrates. The failure of these processes results in structural and functional deficiencies of the cardiac muscle, including inherited cardiomyopathies. These genetic diseases are characterized by cardiac structural and functional anomalies in the absence of abnormal conditions that can explain the observed myocardial abnormality, and are frequently associated with heart failure. Since their original description, major advances have been achieved in the genetic and phenotype knowledge, highlighting the involvement of metabolic abnormalities in their pathogenesis. This review provides a brief overview of the role of mitochondria in the energy metabolism in the heart and focuses on metabolic abnormalities, mitochondrial dysfunction, and storage diseases associated with inherited cardiomyopathies.

High-temperature continuous molecular beam source for aggressive elements: An example of zinc

Expansion of Zn₂ or ZnRg (Rg = rare gas atom) in a molecular supersonic beam constitutes a considerable technical challenge due to the high zinc melting point and high zinc reactivity with stainless steel at high temperatures. In order to overcome these difficulties and meet the requirements for spectroscopy of van der Waals molecules containing zinc, a high-temperature source-module of the supersonic molecular beam for aggressive elements was designed. The module was tested in the laser-induced fluorescence excitation spectroscopy experiment using the b³0_u ⁺4³P₁←X¹0_g ⁺(4¹S₀) bound ← bound transitions in Zn₂. The new source-module can be used for other aggressive elements for which a laser-vaporization technique has been used to date.

Finegoldia magna the cause of hip revision surgery - a two case report

The cause of septic arthritis in 20% of cases is anaerobic bacteria, including infections caused by Finegoldia magna. The occurrence of this pathogen in the etiology of postoperative post-implantive septic joint inflammations is estimated at 5-12% of all anaerobic infections, and 20-40% of all gram-positive anaerobic coccus (GPAC).

CASE REPORTS

The 65-year-old male patient was admitted due to symptoms of pain in the left hip after having undergone arthroplasty three years prior. It was found that the relative length of the left lower limb was shortened by 1.5 cm and there was limited mobility of the left hip joint. The radiological image of the left hip indicated the loosening of the endoprosthesis, which qualified for a revision surgery. During hip revision surgery, the material was collected from the site, for microbiological examination, in which Finegoldia magna was detected, sensitive to Amoxicillin with Clavulanic acid, Clindamycin, Chloramphenicol, Imipenem, Metronidazole and Piperacillin with Tazobactam. Based upon the antibiogram, the patient was given piperacillin with tazobactam (Tazocin, Pfizer) 4 times a day 4.5 g intravenously over 7 days, resulting in a clinical improvement. The 55-year-old female patient was admitted due to recurrent exudates in left trochlear bursa which arose 5 years after left hip arthroplasty. The patient had limited movements in the left hip. Ulrasound diagnostics showed a presence of a thick fluid reservoir located under the fascia in the lateral side of the left thigh measuring 160 x 42 x 25 mm, which had contact with the hip joint. In the radiographic image of the joint, a cyst around the bottom of the implanted acetabular component was revealed. The patient underwent hip revision surgery, and an anaerobic bacterium Finegoldia magna was isolated from a swab taken from the acetabulum. The patient was given piperacillin with tazobactam (Tazocin, Pfizer) 4 times a day 4.5 g intravenously over 7 days, with good clinical effect.

CONCLUSIONS

In both cases, the post-implantation septic infection was triggered by Finegoldia magna. Arthroplasty with subsequent antibiotic therapy resulted in an improvement of the patients' condition and joint reconstruction. In orthopedic practice it should be noted that infections due to the anaerobic bacteria Finegoldia magna may be the cause of complications after the arthroplasty of the joints.

Redox signals at the ER-mitochondria interface control melanoma progression

Reactive oxygen species (ROS) are emerging as important regulators of cancer growth and metastatic spread. However, how cells integrate redox signals to affect cancer progression is not fully understood. Mitochondria are cellular redox hubs, which are highly regulated by interactions with neighboring organelles. Here, we investigated how ROS at the endoplasmic reticulum (ER)-mitochondria interface are generated and translated to affect melanoma outcome. We show that TMX1 and TMX3 oxidoreductases, which promote ER-mitochondria communication, are upregulated in melanoma cells and patient samples. TMX knockdown altered mitochondrial organization, enhanced bioenergetics, and elevated mitochondrial- and NOX4-derived ROS. The TMX-knockdown-induced oxidative stress suppressed melanoma proliferation, migration, and xenograft tumor growth by inhibiting NFAT1. Furthermore, we identified NFAT1-positive and NFAT1-negative melanoma subgroups, wherein NFAT1 expression correlates with melanoma stage and metastatic potential. Integrative bioinformatics revealed that genes coding for mitochondrial- and redox-related proteins are under NFAT1 control and indicated that TMX1, TMX3, and NFAT1 are associated with poor disease outcome. Our study unravels a novel redox-controlled ER-mitochondria-NFAT1 signaling loop that regulates melanoma pathobiology and provides biomarkers indicative of aggressive disease.

Neuronal Redox-Imbalance in Rett Syndrome Affects Mitochondria as Well as Cytosol, and Is Accompanied by Intensified Mitochondrial O 2 Consumption and ROS Release

Rett syndrome (RTT), an X chromosome-linked neurodevelopmental disorder affecting almost exclusively females, is associated with various mitochondrial alterations. Mitochondria are swollen, show altered respiratory rates, and their inner membrane is leaking protons. To advance the understanding of these disturbances and clarify their link to redox impairment and oxidative stress, we assessed mitochondrial respiration in defined brain regions and cardiac tissue of male wildtype (WT) and MeCP2-deficient (Mecp2^-/y) mice. Also, we quantified for the first time neuronal redox-balance with subcellular resolution in cytosol and mitochondrial matrix. Quantitative roGFP1 redox imaging revealed more oxidized conditions in the cytosol of Mecp2^-/y hippocampal neurons than in WT neurons. Furthermore, cytosol and mitochondria of Mecp2^-/y neurons showed exaggerated redox-responses to hypoxia and cell-endogenous reactive oxygen species (ROS) formation. Biochemical analyzes exclude disease-related increases in mitochondrial mass in Mecp2^-/y hippocampus and cortex. Protein levels of complex I core constituents were slightly lower in Mecp2^-/y hippocampus and cortex than in WT; those of complex V were lower in Mecp2^-/y cortex. Respiratory supercomplex-formation did not differ among genotypes. Yet, supplied with the complex II substrate succinate, mitochondria of Mecp2^-/y cortex and hippocampus consumed more O₂ than WT. Furthermore, mitochondria from Mecp2^-/y hippocampus and cortex mediated an enhanced oxidative burden. In conclusion, we further advanced the molecular understanding of mitochondrial dysfunction in RTT. Intensified mitochondrial O₂ consumption, increased mitochondrial ROS generation and disturbed redox balance in mitochondria and cytosol may represent a causal chain, which provokes dysregulated proteins, oxidative tissue damage, and contributes to neuronal network dysfunction in RTT.

Radiological evaluation of the Stoffella metatarsal I osteotomy in the treatment of hallux valgus

The Stoffella surgical method is a reverse Chevron distal metatarsal osteotomy, typically used in younger patients, with good bone quality. The technique is suitable for a variety of cases, from mild to severe, since the head of the first metatarsal may be moved laterally to the edge of the first metatarsal bone, thereby allowing for a significant degree of correction.

AIM

The aim of the paper is to review the radiological results of patients suffering from hallux valgus who underwent Stoffella metatarsal I osteotomy.

MATERIALS AND METHODS

The study has been carried out using a sample of 23 patients, evaluating their pre and post-surgery radiographs. It seeks to examine the effectiveness of the Stoffella metatarsal I osteotomy by measurements of the HVA (Hallux Valgus Angle), IMA (Intermetatarsal Angle), DMAA (Distal Metaphyseal Articular Angle) both prior to and post-surgical correction.

RESULTS

The study demonstrated that the Stoffella Metatarsal I osteotomy has a high rate of success, with correction of the HVA, IMA, DMAA angles, with pre- surgery HVA being 29.7°±6.1°, IMA - 12.9°±3.6°, DMAA - 13.7°±7.1°, Post-surgery results show a mean reduction of 51.28%, 51.13%, 50.56% respectively towards a mean HVA of 14.5°±7.4° (p<0.001), mean IMA of 6.3°±3.7° (p<0.001), mean DMAA of 6.8°±4° (p<0.001). All patients who underwent the surgery had HVA, IMA, DMAA angles within the normal physiological range post-surgery.

CONCLUSIONS

It was concluded that the Stoffella Metatarsal I osteotomy is effective in the correction of the hallux valgus.

CaMKII does not control mitochondrial Ca2+ uptake in cardiac myocytes

KEY POINTS

Mitochondrial Ca²⁺ uptake stimulates the Krebs cycle to regenerate the reduced forms of pyridine nucleotides (NADH, NADPH and FADH₂ ) required for ATP production and reactive oxygen species (ROS) elimination. Ca²⁺ /calmodulin-dependent protein kinase II (CaMKII) has been proposed to regulate mitochondrial Ca²⁺ uptake via mitochondrial Ca²⁺ uniporter phosphorylation. We used two mouse models with either global deletion of CaMKIIδ (CaMKIIδ knockout) or cardiomyocyte-specific deletion of CaMKIIδ and γ (CaMKIIδ/γ double knockout) to interrogate whether CaMKII controls mitochondrial Ca²⁺ uptake in isolated mitochondria and during β-adrenergic stimulation in cardiac myocytes. CaMKIIδ/γ did not control Ca²⁺ uptake, respiration or ROS emission in isolated cardiac mitochondria, nor in isolated cardiac myocytes, during β-adrenergic stimulation and pacing. The results of the present study do not support a relevant role of CaMKII for mitochondrial Ca²⁺ uptake in cardiac myocytes under physiological conditions.

ABSTRACT

Mitochondria are the main source of ATP and reactive oxygen species (ROS) in cardiac myocytes. Furthermore, activation of the mitochondrial permeability transition pore (mPTP) induces programmed cell death. These processes are essentially controlled by Ca²⁺ , which is taken up into mitochondria via the mitochondrial Ca²⁺ uniporter (MCU). It was recently proposed that Ca²⁺ /calmodulin-dependent protein kinase II (CaMKII) regulates Ca²⁺ uptake by interacting with the MCU, thereby affecting mPTP activation and programmed cell death. In the present study, we investigated the role of CaMKII under physiological conditions in which mitochondrial Ca²⁺ uptake matches energy supply to the demand of cardiac myocytes. Accordingly, we measured mitochondrial Ca²⁺ uptake in isolated mitochondria and cardiac myocytes harvested from cardiomyocyte-specific CaMKII δ and γ double knockout (KO) (CaMKIIδ/γ DKO) and global CaMKIIδ KO mice. To simulate a physiological workload increase, cardiac myocytes were subjected to β-adrenergic stimulation (by isoproterenol superfusion) and an increase in stimulation frequency (from 0.5 to 5 Hz). No differences in mitochondrial Ca²⁺ accumulation were detected in isolated mitochondria or cardiac myocytes from both CaMKII KO models compared to wild-type littermates. Mitochondrial redox state and ROS production were unchanged in CaMKIIδ/γ DKO, whereas we observed a mild oxidation of mitochondrial redox state and an increase in H₂ O₂ emission from CaMKIIδ KO cardiac myocytes exposed to an increase in workload. In conclusion, the results obtained in the present study do not support the regulation of mitochondrial Ca²⁺ uptake via the MCU or mPTP activation by CaMKII in cardiac myocytes under physiological conditions.

O2 affects mitochondrial functionality ex vivo

Mitochondria have originated in eukaryotic cells by endosymbiosis of a specialized prokaryote approximately 2 billion years ago. They are essential for normal cell function by providing energy through their role in oxidizing carbon substrates. Glutathione (GSH) is a major thiol-disulfide redox buffer of the cell including the mitochondrial matrix and intermembrane space. We have generated cardiomyocyte-specific Grx1-roGFP2 GSH redox potential (E_GSH) biosensor mice in the past, in which the sensor is targeted to the mitochondrial matrix. Using this mouse model a distinct E_GSH of the mitochondrial matrix (−278.9 ± 0.4 mV) in isolated cardiomyocytes is observed. When analyzing the E_GSH in isolated mitochondria from the transgenic hearts, however, the E_GSH in the mitochondrial matrix is significantly oxidized (−247.7 ± 8.7 mV). This is prevented by adding N-Ethylmaleimide during the mitochondria isolation procedure, which precludes disulfide bond formation. A similar reducing effect is observed by isolating mitochondria in hypoxic (0.1–3% O₂) conditions that mimics mitochondrial pO₂ levels in cellulo. The reduced E_GSH is accompanied by lower ROS production, reduced complex III activity but increased ATP levels produced at baseline and after stimulation with succinate/ADP. Altogether, we demonstrate that oxygenation is an essential factor that needs to be considered when analyzing mitochondrial function ex vivo.

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We identified that mitochondria isolated in room air at 20.9% O₂ exhibit a strong oxidation of the E_GSH in the matrix.

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Isolation of mitochondria in hypoxic conditions mimicking their in cellulo conditions prevents oxidation of the E_GSH.

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Normoxic and hypoxic isolated mitochondria differ in ROS production, complex III activity and ATP levels.

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Oxygenation needs to be considered when analyzing mitochondrial function ex vivo.

The role of mitochondrial cardiolipin in heart function and its implication in cardiac disease

Mitochondria play an essential role in the energy metabolism of the heart. Many of the essential functions are associated with mitochondrial membranes and oxidative phosphorylation driven by the respiratory chain. Mitochondrial membranes are unique in the cell as they contain the phospholipid cardiolipin. The important role of cardiolipin in cardiovascular health is highlighted by several cardiac diseases, in which cardiolipin plays a fundamental role. Barth syndrome, Sengers syndrome, and Dilated cardiomyopathy with ataxia (DCMA) are genetic disorders, which affect cardiolipin biosynthesis. Other cardiovascular diseases including ischemia/reperfusion injury and heart failure are also associated with changes in the cardiolipin pool. Here, we summarize molecular functions of cardiolipin in mitochondrial biogenesis and morphology. We highlight the role of cardiolipin for the respiratory chain, metabolite carriers, and mitochondrial metabolism and describe links to apoptosis and mitochondria specific autophagy (mitophagy) with possible implications in cardiac disease.

Cooperative STAT/NF-κB signaling regulates lymphoma metabolic reprogramming and aberrant GOT2 expression

Knowledge of stromal factors that have a role in the transcriptional regulation of metabolic pathways aside from c-Myc is fundamental to improvements in lymphoma therapy. Using a MYC-inducible human B-cell line, we observed the cooperative activation of STAT3 and NF-κB by IL10 and CpG stimulation. We show that IL10 + CpG-mediated cell proliferation of MYC^low cells depends on glutaminolysis. By ¹³C- and ¹⁵N-tracing of glutamine metabolism and metabolite rescue experiments, we demonstrate that GOT2 provides aspartate and nucleotides to cells with activated or aberrant Jak/STAT and NF-κB signaling. A model of GOT2 transcriptional regulation is proposed, in which the cooperative phosphorylation of STAT3 and direct joint binding of STAT3 and p65/NF-κB to the proximal GOT2 promoter are important. Furthermore, high aberrant GOT2 expression is prognostic in diffuse large B-cell lymphoma underscoring the current findings and importance of stromal factors in lymphoma biology.

Metabolic rewiring of cancer cells can be driven by both extrinsic and intrinsic factors. Here the authors show that microenvironmental factors induce metabolic rewiring of B-cell lymphoma through activation of STAT3 and NF-ΚB resulting in upregulation of the aminotransferase GOT2 and glutamine addiction.

Silver ions are responsible for memory impairment induced by oral administration of silver nanoparticles

Increasing use of silver nanoparticles (AgNPs) results in increased human exposure. AgNPs are able to cross brain-blood barrier and are a risk factor for the brain. Thus, we hypothesized that AgNPs exposure might affect hippocampal dependent memory, which required cognitive coordination processes. To verify the assumption, in this study we evaluated the effects of orally administered bovine serum albumin (BSA)-coated AgNPs on spatial memory, which engage cognitive coordination processes for on-going stimuli segregation. Rats following 28 days of oral administration with 1 mg/kg (n = 10) or 30 mg/kg (n = 10) BSA-AgNPs or saline, a control groups (n = 10, n = 8), were tested with an active place avoidance task in the Carousel Maze test. The study revealed significant impairment of long- and short-term memory, irrespectively of dose of AgNPs, whereas non-cognitive activity was on a similar level. We found significantly higher content of silver in the hippocampus in comparison to the lateral cortex. No silver was found in the cerebellum and the frontal cortex. The nanoSIMS analysis reveal a weak signal of silver in the hippocampus of AgNPs treated animals that should be attributed to the presence of silver in ionic form rather than AgNPs. Our findings indicate that oral exposure to a low dose AgNPs induces detrimental effect on memory and cognitive coordination processes. The presence of silver ions rather than AgNPs in different brain regions, in particular the hippocampus, suggests crucial role of silver ions in AgNPs-induced impairment of the higher brain functions.

The mitochondrial TMEM177 associates with COX20 during COX2 biogenesis

The three mitochondrial-encoded proteins, COX1, COX2, and COX3, form the core of the cytochrome c oxidase. Upon synthesis, COX2 engages with COX20 in the inner mitochondrial membrane, a scaffold protein that recruits metallochaperones for copper delivery to the CuA-Site of COX2. Here we identified the human protein, TMEM177 as a constituent of the COX20 interaction network. Loss or increase in the amount of TMEM177 affects COX20 abundance leading to reduced or increased COX20 levels respectively. TMEM177 associates with newly synthesized COX2 and SCO2 in a COX20-dependent manner. Our data shows that by unbalancing the amount of TMEM177, newly synthesized COX2 accumulates in a COX20-associated state. We conclude that TMEM177 promotes assembly of COX2 at the level of CuA-site formation.

Role of Cardiolipin in Mitochondrial Signaling Pathways

The phospholipid cardiolipin (CL) is an essential constituent of mitochondrial membranes and plays a role in many mitochondrial processes, including respiration and energy conversion. Pathological changes in CL amount or species composition can have deleterious consequences for mitochondrial function and trigger the production of reactive oxygen species. Signaling networks monitor mitochondrial function and trigger an adequate cellular response. Here, we summarize the role of CL in cellular signaling pathways and focus on tissues with high-energy demand, like the heart. CL itself was recently identified as a precursor for the formation of lipid mediators. We highlight the concept of CL as a signaling platform. CL is exposed to the outer mitochondrial membrane upon mitochondrial stress and CL domains serve as a binding site in many cellular signaling events. During mitophagy, CL interacts with essential players of mitophagy like Beclin 1 and recruits the autophagic machinery by its interaction with LC3. Apoptotic signaling pathways require CL as a binding platform to recruit apoptotic factors such as tBid, Bax, caspase-8. CL required for the activation of the inflammasome and plays a role in inflammatory signaling. As changes in CL species composition has been observed in many diseases, the signaling pathways described here may play a general role in pathology.

Barth syndrome cardiomyopathy

Barth syndrome (BTHS) is an inherited form of cardiomyopathy, caused by a mutation within the gene encoding the mitochondrial transacylase tafazzin. Tafazzin is involved in the biosynthesis of the unique phospholipid cardiolipin (CL), which is almost exclusively found in mitochondrial membranes. CL directly interacts with a number of essential protein complexes in the mitochondrial membranes including the respiratory chain, mitochondrial metabolite carriers, and proteins, involved in shaping mitochondrial morphology. Here we describe, how in BTHS CL deficiency causes changes in the morphology of mitochondria, structural changes in the respiratory chain, decreased respiration, and increased generation of reactive oxygen species. A large number of cellular and animal models for BTHS have been established to elucidate how mitochondrial dysfunction induces sarcomere disorganization and reduced contractility, resulting in dilated cardiomyopathy in vivo.

The Degradation Pathway of the Mitophagy Receptor Atg32 Is Re-Routed by a Posttranslational Modification

The outer mitochondrial membrane protein Atg32 is the central receptor for mitophagy, the mitochondria-specific form of autophagy. Atg32 is an unstable protein, and is rapidly degraded under conditions in which mitophagy is not induced. Here we show that Atg32 undergoes a posttranslational modification upon induction of mitophagy. The modification is dependent on the core autophagic machinery, including Atg8, and on the mitophagy-specific adaptor protein Atg11. The modified Atg32 is targeted to the vacuole where it becomes stabilized when vacuolar proteases are deficient. Interestingly, we find that this degradation pathway differs from the degradation pathway of non-modified Atg32, which neither involves vacuolar proteases, nor the proteasome. These analyses reveal that a posttranslational modification discriminates a form of Atg32 targeting mitochondria for mitophagy from that, which escapes mitophagy by rapid degradation.

New precipitation method for isolation of 99mTc from irradiated 100Mo target

Technetium-99m is the most widely used radionuclide in nuclear medicine. This work describes the method to separate ^99mTc from irradiated ¹⁰⁰Mo target. For this purpose we utilized formation of ammonium molybdenum phosphate (AMP) and have optimized the four parameters of the process. The proposed process is promising and allows fast separation of macroamounts of molybdenum without co-precipitation of ^99mTc. The concentration of molybdenum in solution after precipitation of AMP was lower than 300 µg ml⁻¹. Additional purification using AnaLigTc-02 is required to obtain solution with lower concentration of molybdenum.

Phospho-ubiquitin-PARK2 complex as a marker for mitophagy defects

The E3 ubiquitin ligase PARK2 and the mitochondrial protein kinase PINK1 are required for the initiation of mitochondrial damage-induced mitophagy. Together, PARK2 and PINK1 generate a phospho-ubiquitin signal on outer mitochondrial membrane proteins that triggers recruitment of the autophagy machinery. This paper describes the detection of a defined 500-kDa phospho-ubiquitin-rich PARK2 complex that accumulates on mitochondria upon treatment with the membrane uncoupler CCCP. Formation of this complex is dependent on the presence of PINK1 and is absent in mutant forms of PARK2, whereby mitophagy is also arrested. These results signify a functional signaling complex that is essential for the progression of mitophagy. The visualization of the PARK2 signaling complex represents a novel marker for this critical step in mitophagy and can be used to monitor mitophagy progression in PARK2 mutants and to uncover additional upstream factors required for PARK2-mediated mitophagy signaling.

TIM29 is a subunit of the human carrier translocase required for protein transport

Hydrophobic inner mitochondrial membrane proteins with internal targeting signals, such as the metabolite carriers, use the carrier translocase (TIM22 complex) for transport into the inner membrane. Defects in this transport pathway have been associated with neurodegenerative disorders. While the TIM22 complex is well studied in baker's yeast, very little is known about the mammalian TIM22 complex. Using immunoprecipitation, we purified the human carrier translocase and identified a mitochondrial inner membrane protein TIM29 as a novel component, specific to metazoa. We show that TIM29 is a constituent of the 440 kDa TIM22 complex and interacts with oxidized TIM22. Our analyses demonstrate that TIM29 is required for the structural integrity of the TIM22 complex and for import of substrate proteins by the carrier translocase.

Cardiac-specific succinate dehydrogenase deficiency in Barth syndrome

Barth syndrome (BTHS) is a cardiomyopathy caused by the loss of tafazzin, a mitochondrial acyltransferase involved in the maturation of the glycerophospholipid cardiolipin. It has remained enigmatic as to why a systemic loss of cardiolipin leads to cardiomyopathy. Using a genetic ablation of tafazzin function in the BTHS mouse model, we identified severe structural changes in respiratory chain supercomplexes at a pre-onset stage of the disease. This reorganization of supercomplexes was specific to cardiac tissue and could be recapitulated in cardiomyocytes derived from BTHS patients. Moreover, our analyses demonstrate a cardiac-specific loss of succinate dehydrogenase (SDH), an enzyme linking the respiratory chain with the tricarboxylic acid cycle. As a similar defect of SDH is apparent in patient cell-derived cardiomyocytes, we conclude that these defects represent a molecular basis for the cardiac pathology in Barth syndrome.

Preparation of water samples for proficiency testing on radionuclides

The Institute of Nuclear Chemistry and Technology (INCT) procedure for preparation of water samples for proficiency testing on determination of (241)Am, (137)Cs, (239)Pu, (226)Ra and (90)Sr in water is presented. Natural waters were applied as the raw materials and spiked with the aforementioned radionuclides. The procedure of spiking water allows to prevent losses of the radionuclides and to assign property values from formulation. The main advantages of this procedure are (i) similarity of the test materials to the water samples routinely analysed by radioanalytical laboratories, and (ii) traceable assigned values with low uncertainties.

Sports injuries in Plus League volleyball players

AIM

Although physical activity brings a range of lifelong health benefits, it may also lead to injuries that pose a significant threat to health. It is particularly noticeable in people involved in professional sports where sport-related injuries commonly occur and are associated with intense exercise which aims to improve physical fitness. The article attempts to determine incidence of sports injuries reported by Plus League volleyball players, as well as to identify their most common types and causes.

METHODS

The research project involved 90 Plus League volleyball players aged 18-37 with the average age of 25.11 (SD±5.378). A method of diagnostic survey was applied to collect empirical data by means of questionnaire developed by the authors (researchers). The results were statistically analysed and verified with the analysis of variance (ANOVA) and χ2 test at the significance level (or critical P-value) of P≤0.05.

RESULTS

Over 87% of the respondents suffered from at least one sport-related injury. In total, 362 injuries occurred, on average 4.02 injuries per one volleyball player. The most common sports injuries involved ankle or talocrural joint (46 injuries), knee and lower leg muscles (30), interphalangeal articulations of fingers (30) as well as shoulder joint. More than half of the injuries (57%) occurred twice or three times. Volleyball players commonly sustain injuries through contact with an opposing player in competition. Sport-specific injuries may also occur due to exhaustion, lack of rest and undertreated injuries.

CONCLUSION

The most common volleyball-related injuries are primarily talocrural joint, hand and shoulder injuries. Common types of injuries that can affect volleyball players include muscles, joints and ligaments injuries, sprains and strains as well as bruises. Most of these injuries are caused by exhaustion, contact with an opposing player during competition and fatigue. The incidence of sport-related injuries seems to be influenced by such factors as somatic features, jumping parameters and the length of professional volleyball career.

Aim24 stabilizes respiratory chain supercomplexes and is required for efficient respiration

The mitochondrial respiratory chain is essential for the conversion of energy derived from the oxidation of metabolites into the membrane potential, which drives the synthesis of ATP. The electron transporting complexes bc1 complex and the cytochrome c oxidase assemble into large supercomplexes, allowing efficient energy transduction. Currently, we have only limited information about what determines the structure of the supercomplex. Here, we characterize Aim24 in baker's yeast as a protein, which is integrated in the mitochondrial inner membrane and is required for the structural integrity of the supercomplex. Deletion of AIM24 strongly affects activity of the respiratory chain and induces a growth defect on non-fermentable medium. Our data indicate that Aim24 has a function in stabilizing the respiratory chain supercomplexes.

Uth1 is a mitochondrial inner membrane protein dispensable for post-log-phase and rapamycin-induced mitophagy

Mitochondria are turned over by an autophagic process termed mitophagy. This process is considered to remove damaged, superfluous and aged organelles. However, little is known about how defective organelles are recognized, what types of damage induce turnover, and whether an identical set of factors contributes to degradation under different conditions. Here we systematically compared the mitophagy rate and requirement for mitophagy-specific proteins during post-log-phase and rapamycin-induced mitophagy. To specifically assess mitophagy of damaged mitochondria, we analyzed cells accumulating proteins prone to degradation due to lack of the mitochondrial AAA-protease Yme1. While autophagy 32 (Atg32) was required under all tested conditions, the function of Atg33 could be partially bypassed in post-log-phase and rapamycin-induced mitophagy. Unexpectedly, we found that Uth1 was dispensable for mitophagy. A re-evaluation of its mitochondrial localization revealed that Uth1 is a protein of the inner mitochondrial membrane that is targeted by a cleavable N-terminal pre-sequence. In agreement with our functional analyses, this finding excludes a role of Uth1 as a mitochondrial surface receptor.

Cardiolipin deficiency affects respiratory chain function and organization in an induced pluripotent stem cell model of Barth syndrome

Barth syndrome (BTHS) patients carrying mutations in tafazzin (TAZ1), which is involved in the final maturation of cardiolipin, present with dilated cardiomyopathy, skeletal myopathy, growth retardation and neutropenia. To study how mitochondrial function is impaired in BTHS patients, we generated induced pluripotent stem cells (iPSCs) to develop a novel and relevant human model system for BTHS. BTHS-iPSCs generated from dermal fibroblasts of three patients with different mutations in TAZ1 expressed pluripotency markers, and were able to differentiate into cells derived from all three germ layers both in vitro and in vivo. We used these cells to study the impact of tafazzin deficiency on mitochondrial oxidative phosphorylation. We found an impaired remodeling of cardiolipin, a dramatic decrease in basal oxygen consumption rate and in the maximal respiratory capacity in BTHS-iPSCs. Simultaneous measurement of extra-cellular acidification rate allowed us a thorough assessment of the metabolic deficiency in BTHS patients. Blue native gel analyses revealed that decreased respiration coincided with dramatic structural changes in respiratory chain supercomplexes leading to a massive increase in generation of reactive oxygen species. Our data demonstrate that BTHS-iPSCs are capable of modeling BTHS by recapitulating the disease phenotype and thus are important tools for studying the disease mechanism.