Rewired glutamate metabolism diminishes cytostatic action of L-asparaginase.

Tumor cells often adapt to amino acid deprivation through metabolic rewiring, compensating for the loss with alternative amino acids/substrates. We have described such a scenario in leukemic cells treated with L-asparaginase (ASNase). Clinical effect of ASNase is based on nutrient stress achieved by its dual enzymatic action which leads to depletion of asparagine and glutamine and is accompanied with elevated aspartate and glutamate concentrations in serum of acute lymphoblastic leukemia patients. We showed that in these limited conditions glutamate uptake compensates for the loss of glutamine availability. Extracellular glutamate flux detection confirms its integration into the TCA cycle and its participation in nucleotide and glutathione synthesis. Importantly, it is glutamate-driven de novo synthesis of glutathione which is the essential metabolic pathway necessary for glutamate's pro-survival effect. In vivo findings support this effect by showing that inhibition of glutamate transporters enhances the therapeutic effect of ASNase. In summary, ASNase induces elevated extracellular glutamate levels under nutrient stress, which leads to a rewiring of intracellular glutamate metabolism and has a negative impact on ASNase treatment.

Characterization of Clinical Phenotypes in Congenital Myasthenic Syndrome Associated with the c.1327delG Frameshift Mutation in CHRNE Encoding the Acetylcholine Receptor Epsilon Subunit.

Background: Congenital myasthenic syndromes (CMS) are a group of rare but often treatable inherited disorders of neuromuscular transmission characterized by fatigable skeletal muscle weakness. In this paper we present the largest phenotypic analysis to date of a cohort of patients carrying the pathogenic variant c.1327delG in the CHRNE gene, leading to CHRNE-CMS. Objective: This study aims to identify the phenotypic variability in CMS associated with c.1327delG mutation in the CHRNE gene. Methods: Disease specific symptoms were assessed using specific standardized tests for autoimmune myasthenia (Quantitative Myasthenia Gravis score) as well as patient-reported scales for symptom severity. Evaluated clinical manifestations included ocular symptoms (ophthalmoparesis and ptosis), bulbar weakness, axial muscle weakness, proximal and distal muscle weakness, and respiratory function. Patients were allocated into three groups according to clinical impression of disease severity: mild, moderate, and severe. Results: We studied 91 Bulgarian Roma patients, carrying the same causative homozygous CHRNE c.1327delG mutation. Bulbar weakness was present in patients throughout all levels of severity of CHRNE-CMS in this study. However, difficulties in eating and swallowing are more prominent characteristics in the moderate and severe clinical phenotypes. Diplopia and ptosis resulting from fatigue of the extraocular muscles were permanent features regardless of disease severity or age. Levels of axial, proximal and distal muscle weakness were variable between disease groups. The statistical analysis showed significant differences between the patients in the three groups, emphasizing a possible variation in symptom manifestation in the evaluated patient population despite the disease originating from the same genetic mutation. Impairment of respiratory function was more prominent in severely affected patients, which might result from loss of compensatory muscle function in those individuals. Conclusion: Results from our study indicate significant phenotypic heterogeneity leading to mild, moderate, or severe clinical manifestation in CHRNE-CMS, despite the genotypic homogeneity.

Stepwise molecular-genetic examination in aborted fetuses.

OBJECTIVE: The evaluation of quantitative fluorescence PCR (QF-PCR) and single nucleotide polymorphism array (SNP array) analysis for the identification of chromosomal abnormalities in products of conception (POC). MATERIALS AND METHODS: A total of 1,094 POC samples were processed at Gennet in the years 2018-2020. Chromosomal aneuploidies were tested by QF-PCR using a Omnibor set (STR markers 13, 18, 21, X a Y), SAB-I set (STR markers 2, 7, 15, 16, 22), SAB-II set (from November 2019, STR markers 4, 6, 14) followed by SNP array analysis (Illumina) on samples with a negative QF-PCR result. All POC samples were tested for maternal contamination. RESULTS: After exclusion of maternal contamination (32% samples) the total number of 742 POC samples were tested by QF-PCR. Chromosomal aneuploidies were found in 273 POC samples (36.8%). Then, 469 QF-PCR negative POC samples were tested by SNP array analysis. Normal female/male profile was confirmed in 402 samples (85.7%) and chromosomal aneuploidies and chromosomal aberrations (deletion/duplication > 10 Mb) in 51 samples (10.9%). Microdeletion/microduplication was found in 16 POC samples (3.4%), two were classified as pathogenic variants and 14 as variants of unknown significance. In a group of women > 35 years of age, statistically significant increase of the chromosomal abnormalities was confirmed. No statistically significant difference between the in vitro fertilization group and the group of spontaneous conception was found. CONCLUSION: The application of the molecular work-up based on the stepwise use of QF-PCR and SNP array clarifies the cause of the abortion in 43% POC samples. The overall detection rate in the I. trimester was 50.4%.

The clinical value of circulating free tumor DNA in testicular germ cell tumor patients.

BACKGROUND: Testicular germ cell tumors (TGCT) are unique malignancies of young adult men; their biology is, however, underexplored and there has not been much progress in their treatment for decades. Circulating free tumor DNA (cfDNA) analysis represents a promising way of discovering novel diagnostic and treatment options. OBJECTIVE: The study evaluates the clinical value of cfDNA detection in TGCT patients. DESIGN AND METHODS: Total cfDNA concentration and ratio of its 2 main fragments (180 and 360 bp) were evaluated by spectrophotometry, capillary electrophoresis and qPCR in peripheral blood plasma of 96 TGCT patients (173 samples) and 31 normal controls. Non-parametric tests were used for statistical analyses. RESULTS: The total cfDNA concentration was significantly higher in TGCT than in controls (P < 0.0001), with the highest levels at disease progression, but with no clear threshold between malignant and normal samples. Patients with positive tumor markers had higher cfDNA concentrations than those with negative markers (P = 0.01). Longer 360 bp cfDNA fragments were found in 58% of TGCT patients including almost all samples from relapse or disease progression but no normal controls (P < 0.0001). CONCLUSION: Total cfDNA levels are significantly increased in TGCT patients but without a clear threshold separating normal and tumor samples, thus total cfDNA amount itself is not a sensitive enough marker to identify or monitor TGCT. Longer cfDNA fragments have been found exclusively in a proportion of tumors and predominantly at disease progression, representing a novel potential marker for TGCT monitoring that would deserve further exploration.

Evoked Potentials in Patients With Wilson Disease.

INTRODUCTION: Wilson disease (WD) is an inherited disorder of copper metabolism presenting with a variety of symptoms but commonly as a liver or neuropsychiatric disease. Abnormal evoked responses are constantly found among patients with neurologic manifestations and sometimes in patients with hepatic presentation or in presymptomatic siblings. The aim of our study was to assess visual and brainstem auditory evoked potentials (BAEP) in patients with various presentation of WD. METHODS: Visual evoked potentials (VEP) were performed in 36 WD patients and BAEP were done in 37 WD patients. RESULTS: Brainstem auditory evoked potentials were normal in patients with isolated hepatic presentation, whereas they were abnormal in 93.5% of patients with neurologic symptoms. There was significant prolongation of the latencies of the III and V waves and of the interpeak III-V and I-V latencies in comparison with the healthy controls (T-test P = 0). Abnormal VEP were observed in 81% of the patients including six of seven neurologically asymptomatic patients. The values of N75, P100, and N145 latencies were significantly longer in all patients than in healthy controls (T-test). CONCLUSIONS: The data showed that VEP and BAEP are more frequently abnormal in WD than previously reported. The abnormal VEP and BAEP even without clinical signs and brain MRI abnormalities point to subclinical involvement of visual and auditory pathways caused by copper toxicity. Because VEP and BAEP are noninvasive and widely available, they should be performed in all patents with WD.

Management of transthyretin amyloidosis.

Transthyretin amyloidosis (ATTR amyloidosis) is a disease caused by deposition of transthyretin fibrils in organs and tissues, which causes their dysfunction. The clinical heterogeneity of ATTR amyloidosis and the variable presentation of symptoms at early disease stages, historically meant treatment delays. Diagnostic tools and therapy options of ATTR amyloidosis have markedly improved in recent years. The first Swiss Amyloidosis Network (SAN) meeting (Zurich, Switzerland, January 2020) aimed to define a consensus statement regarding the diagnostic work-up and treatment for systemic amyloidosis, tailored to the Swiss healthcare system. A consortium of 45 clinicians and researchers from all Swiss regions and universities was selected by the SAN committee to represent all sub-specialty groups involved in care of patients with amyloidosis. A steering committee conducted the literature search and analysis, wrote the critical synthesis and elaborated a list of statements that were evaluated by all the participants. These recommendations will improve outcomes and quality of life for patients with ATTR amyloidosis. A global review of these guidelines is planned every 3 years with a formal meeting of all the involved experts.

Collagen VI-Related Myopathy Caused by Compound Heterozygous Mutations of COL6A3 in a Consanguineous Kurdish Family.

ABSTRACT: Collagen VI-related myopathies are caused by mutations of COL6A1, COL6A2, and COL6A3 and present with a wide phenotypic spectrum ranging from severe Ulrich congenital muscular dystrophy to mild Bethlem myopathy. Here, we report a consanguineous Kurdish family with 3 siblings affected by autosomal-recessive Bethlem myopathy caused by compound heterozygous mutations of COL6A3. We found the previously described missense mutation c.7447A > G/p.(Lys2483Glu) and a novel large deletion encompassing the exon 1-39 of the COL6A3 gene. Apart from the classical clinical symptoms, all patients had keratoconus, which expands the phenotype of the collagen VI-related myopathies.

Expert recommendation from the Swiss Amyloidosis Network (SAN) for systemic AL-amyloidosis.

Systemic amyloidosis is a heterogeneous group of diseases associated with protein misfolding into insoluble beta-sheet rich structures that deposit extracellularly in different organs, eventually compromising their function. There are more than 30 different proteins, known to be amyloidogenic with “light chain” (AL)-amyloidosis being the most common type, followed by transthyretin (ATTR)-, and amyloid protein A (AA)-amyloidosis. Systemic amyloidosis is a rare disease with an incidence of around 10 patients in 1 million inhabitants. Recently several new therapeutic options have been developed for subgroups of amyloidosis patients, and the introduction of novel therapies for plasma cell myeloma has led to an increase in the therapeutic armamentarium for plasma cell disorders, including AL amyloidosis. Among them, proteasome inhibitors, immunomodulatory agents (-imids), and monoclonal antibodies have been successfully introduced into clinical practice. Still, high-quality data from randomised controlled trials regarding the benefit of these cost-intensive drugs in AL amyloidosis are widely lacking, and due to the rarity of the disease many physicians will not gain routine experience in the management of these frail patients. The diagnosis of AL amyloidosis relies on a close collaboration between clinicians, pathologists, imaging experts, and sometimes geneticists. Diagnosis and treatment options in this complex disorder should be discussed in dedicated multidisciplinary boards. In January 2020, the first meeting of the Swiss Amyloidosis Network took place in Zurich, Switzerland. One aim of this meeting was to establish a consensus guideline regarding the diagnostic work-up and the treatment recommendations for systemic amyloidosis tailored to the Swiss health care system. Forty-five participants from different fields in medicine discussed many aspects of amyloidosis. These are the Swiss Amyloidosis Network recommendations which focus on diagnostic work-up and treatment of AL-amyloidosis.

Molecular Basis of Cisplatin Resistance in Testicular Germ Cell Tumors.

The emergence of cisplatin (CDDP) resistance is the main cause of treatment failure and death in patients with testicular germ cell tumors (TGCT), but its biologic background is poorly understood. To study the molecular basis of CDDP resistance in TGCT we prepared and sequenced CDDP-exposed TGCT cell lines as well as 31 primary patients' samples. Long-term exposure to CDDP increased the CDDP resistance 10 times in the NCCIT cell line, while no major resistance was achieved in Tera-2. Development of CDDP resistance was accompanied by changes in the cell cycle (increase in G1 and decrease in S-fraction), increased number of acquired mutations, of which 3 were present within ATRX gene, as well as changes in gene expression pattern. Copy number variation analysis showed, apart from obligatory gain of 12p, several other large-scale gains (chr 1, 17, 20, 21) and losses (chr X), with additional more CNVs found in CDDP-resistant cells (e.g., further losses on chr 1, 4, 18, and gain on chr 8). In the patients' samples, those who developed CDDP resistance and died of TGCT (2/31) showed high numbers of acquired aberrations, both SNPs and CNVs, and harbored mutations in genes potentially relevant to TGCT development (e.g., TRERF1, TFAP2C in one patient, MAP2K1 and NSD1 in another one). Among all primary tumor samples, the most commonly mutated gene was NSD1, affected in 9/31 patients. This gene encoding histone methyl transferase was also downregulated and identified among the 50 most differentially expressed genes in CDDP-resistant NCCIT cell line. Interestingly, 2/31 TGCT patients harbored mutations in the ATRX gene encoding a chromatin modifier that has been shown to have a critical function in sexual differentiation. Our research newly highlights its probable involvement also in testicular tumors. Both findings support the emerging role of altered epigenetic gene regulation in TGCT and CDDP resistance development.

Satellite cell content in Huntington's disease patients in response to endurance training.

BACKGROUND: Skeletal muscle wasting is a hallmark of Huntington's disease (HD). However, data on myocellular characteristics and myofiber remodeling in HD patients are scarce. We aimed at gaining insights into myocellular characteristics of HD patients as compared to healthy controls at rest and after a period of increased skeletal muscle turnover. METHODS: Myosin heavy chain (MyHC)-specific cross-sectional area, satellite cell content, myonuclear number, myonuclear domain, and muscle fiber type distribution were determined from vastus lateralis muscle biopsies at rest and after 26 weeks of endurance training in HD patients and healthy controls. RESULTS: At the beginning of the study, there were no differences in myocellular characteristics between HD patients and healthy controls. Satellite cell content per MyHC-1 fiber (P = 0.014) and per MyHC-1 myonucleus (P = 0.006) increased significantly in healthy controls during the endurance training intervention, whereas it remained constant in HD patients (P = 0.804 and P = 0.975 for satellite cell content per MyHC-1 fiber and myonucleus, respectively). All further variables were not altered during the training intervention in HD patients and healthy controls. CONCLUSIONS: Similar skeletal muscle characteristics between HD patients and healthy controls at baseline suggested similar potential for myofiber remodeling in response to exercise. However, the missing satellite cell response in MyHC-1 myofibers following endurance training in HD patients points to a potential dysregulation in the exercise-induced activation and/or proliferation of satellite cells. In the longer-term, impaired myonuclear turnover might be associated with the clinical observation of skeletal muscle wasting.

Effects of endurance training on skeletal muscle mitochondrial function in Huntington disease patients.

BACKGROUND: Mitochondrial dysfunction may represent a pathogenic factor in Huntington disease (HD). Physical exercise leads to enhanced mitochondrial function in healthy participants. However, data on effects of physical exercise on HD skeletal muscle remains scarce. We aimed at investigating adaptations of the skeletal muscle mitochondria to endurance training in HD patients. METHODS: Thirteen HD patients and 11 healthy controls completed 26 weeks of endurance training. Before and after the training phase muscle biopsies were obtained from M. vastus lateralis. Mitochondrial respiratory chain complex activities, mitochondrial respiratory capacity, capillarization, and muscle fiber type distribution were determined from muscle samples. RESULTS: Citrate synthase activity increased during the training intervention in the whole cohort (P = 0.006). There was no group x time interaction for citrate synthase activity during the training intervention (P = 0.522). Complex III (P = 0.008), Complex V (P = 0.043), and succinate cytochrome c reductase (P = 0.008) activities increased in HD patients and controls by endurance training. An increase in mass-specific mitochondrial respiratory capacity was present in HD patients during the endurance training intervention. Overall capillary-to-fiber ratio increased in HD patients by 8.4% and in healthy controls by 6.4% during the endurance training intervention. CONCLUSIONS: Skeletal muscle mitochondria of HD patients are equally responsive to an endurance-training stimulus as in healthy controls. Endurance training is a safe and feasible option to enhance indices of energy metabolism in skeletal muscle of HD patients and may represent a potential therapeutic approach to delay the onset and/or progression of muscular dysfunction. TRIAL REGISTRATION: ClinicalTrials.gov NCT01879267 . Registered May 24, 2012.

Exercise effects in Huntington disease.

Huntington disease (HD) is a relentlessly progressive neurodegenerative disorder with symptoms across a wide range of neurological domains, including cognitive and motor dysfunction. There is still no causative treatment for HD but environmental factors such as passive lifestyle may modulate disease onset and progression. In humans, multidisciplinary rehabilitation has a positive impact on cognitive functions. However, a specific role for exercise as a component of an environmental enrichment effect has been difficult to demonstrate. We aimed at investigating whether endurance training (ET) stabilizes the progression of motor and cognitive dysfunction and ameliorates cardiovascular function in HD patients. Twelve male HD patients (mean ± SD, 54.8 ± 7.1 years) and twelve male controls (49.1 ± 6.8 years) completed 26 weeks of endurance training. Before and after the training intervention, clinical assessments, exercise physiological tests, and a body composition measurement were conducted and a muscle biopsy was taken from M. vastus lateralis. To examine the natural course of the disease, HD patients were additionally assessed 6 months prior to ET. During the ET period, there was a motor deficit stabilization as indicated by the Unified Huntington's Disease Rating Scale motor section score in HD patients (baseline: 18.6 ± 9.2, pre-training: 26.0 ± 13.7, post-training: 26.8 ± 16.4). Peak oxygen uptake ([Formula: see text]) significantly increased in HD patients (∆[Formula: see text] = +0.33 ± 0.28 l) and controls (∆[Formula: see text] = +0.29 ± 0.41 l). No adverse effects of the training intervention were reported. Our results confirm that HD patients are amenable to a specific exercise-induced therapeutic strategy indicated by an increased cardiovascular function and a stabilization of motor function.

Altered skeletal muscle (mitochondrial) properties in patients with mitochondrial DNA single deletion myopathy.

BACKGROUND: Mitochondrial myopathy severely affects skeletal muscle structure and function resulting in defective oxidative phosphorylation. However, the major pathomechanisms and therewith effective treatment approaches remain elusive. Therefore, the aim of the present study was to investigate disease-related impairments in skeletal muscle properties in patients with mitochondrial myopathy. Accordingly, skeletal muscle biopsies were obtained from six patients with moleculargenetically diagnosed mitochondrial myopathy (one male and five females, 53 ± 9 years) and eight age- and gender-matched healthy controls (two males and six females, 58 ± 14 years) to determine mitochondrial respiratory capacity of complex I-V, mitochondrial volume density and fiber type distribution. RESULTS: Mitochondrial volume density (4.0 ± 0.5 vs. 5.1 ± 0.8 %) as well as respiratory capacity of complex I-V were lower (P < 0.05) in mitochondrial myopathy and associated with a higher (P < 0.001) proportion of type II fibers (65.2 ± 3.6 vs. 44.3 ± 5.9 %). Additionally, mitochondrial volume density and maximal oxidative phosphorylation capacity correlated positively (P < 0.05) to peak oxygen uptake. CONCLUSION: Mitochondrial myopathy leads to impaired mitochondrial quantity and quality and a shift towards a more glycolytic skeletal muscle phenotype.

GNE myopathy in Roma patients homozygous for the p.I618T founder mutation.

GNE myopathy is an autosomal-recessive disorder caused by mutations in the GNE gene, encoding the key enzyme in the sialic acid biosynthetic pathway, UDP-N-acetylglucosamine 2-epimerase/N-acetyl mannosamine kinase. We studied 50 Bulgarian Roma patients homozygous for p.I618T, an ancient founder mutation in the kinase domain of the GNE gene, dating before the Gypsy exodus from North West India. The clinical features in the Bulgarian GNE group can be described with disease onset mostly in the third decade, but in individual cases, onset was as early as 10 years of age. The majority of patients had foot drop as the first symptom, but three patients developed hand weakness first. Muscle weakness was early and severe for the tibialis anterior, and minimal or late for quadriceps femoris, and respiratory muscles were only subclinically affected even in the advanced stages of the disease. During a 15-year follow-up period, 32 patients became non-ambulant. The average period between disease onset and loss of ambulation was 10.34 ± 4.31 years, ranging from 3 to 20 years. Our analysis of affected sib pairs suggested a possible role of genetic modifying factors, accounting for significant variation in disease severity.