Abnormal calcium signalling and the caffeine-halothane contracture test.

BACKGROUND: The variable clinical presentation of malignant hyperthermia (MH), a disorder of calcium signalling, hinders its diagnosis and management. Diagnosis relies on the caffeine-halothane contracture test, measuring contraction forces upon exposure of muscle to caffeine or halothane (FC and FH, respectively). Patients with above-threshold FC or FH are diagnosed as MH susceptible. Many patients test positive to halothane only (termed 'HH'). Our objective was to determine the characteristics of these HH patients, including their clinical symptoms and features of cytosolic Ca2+ signalling related to excitation-contraction coupling in myotubes. METHODS: After institutional ethics committee approval, recruited patients undergoing contracture testing at Toronto's MH centre were assigned to three groups: HH, doubly positive (HS), and negative patients (HN). A clinical index was assembled from musculoskeletal symptoms and signs. An analogous calcium index summarised four measures in cultured myotubes: resting [Ca2+]cytosol, frequency of spontaneous cytosolic Ca2+ events, Ca2+ waves, and cell-wide Ca2+ spikes after electrical stimulation. RESULTS: The highest values of both indexes were found in the HH group; the differences in calcium index between HH and the other groups were statistically significant. The principal component analysis confirmed the unique cell-level features of the HH group, and identified elevated resting [Ca2+]cytosol and spontaneous event frequency as the defining HH characteristics. CONCLUSIONS: These findings suggest that HH pathogenesis stems from excess Ca2+ leak through sarcoplasmic reticulum channels. This identifies HH as a separate diagnostic group and opens their condition to treatment based on understanding of pathophysiological mechanisms.

Genetic variation and cognitive dysfunction one year after cardiac surgery.

Various studies have implicated a potential association between candidate gene polymorphisms and postoperative cognitive dysfunction, yet corroborative studies are lacking. We investigated the variants in genes encoding platelet glycoprotein-IIIa and apolipoprotein-E and their relationship with postoperative cognitive dysfunction one year after cardiac surgery. A total of 155 patients were studied; neuropsychological testing demonstrated cognitive dysfunction in 31 (20%) patients at one-year follow-up. No differences were detected with respect to baseline characteristics, pre-operative variables and surgical data between the patients with and without cognitive dysfunction. The Pl(A2) -allele of the platelet glycoprotein-IIIa gene was present in 13 (42%) and 25 (20%) patients with and without cognitive dysfunction, respectively, p = 0.012. The apolipoprotein E-ε4 allele was present in 9 (29%) and 24 (19%) patients with and without cognitive dysfunction, respectively, p = 0.24. Both the Pl(A2) and apolipoprotein-ε4 alleles were present together in 6 (19%) and 5 (4%) patients with and without cognitive dysfunction, respectively, p = 0.003. Validation of these findings is required in age-adjusted non-surgical controls.

Ecstacy-induced delayed rhabdomyolysis and neuroleptic malignant syndrome in a patient with a novel variant in the ryanodine receptor type 1 gene.

We present the case of a 20-year-old woman who developed rhabdomyolysis, disseminated intravascular coagulopathy and multi-organ failure induced by ecstasy. Following initial improvement, she developed delayed rhabdomyolysis then haloperidol-induced neuroleptic malignant syndrome, which was treated with a total of 50 mg.kg(-1) dantrolene. Subsequent genetic testing revealed a novel potentially pathogenic variant in the ryanodine receptor type 1 gene. However, caffeine-halothane contracture testing of the patient's mother who carried the same gene variant was negative for malignant hyperthermia.

Compound RYR1 heterozygosity resulting in a complex phenotype of malignant hyperthermia susceptibility and a core myopathy.

Malignant hyperthermia (MH) is a potentially fatal pharmacogenetic myopathy triggered by exposure to volatile anesthetics and/or depolarizing muscle relaxants. Susceptibility to MH is primarily associated with dominant mutations in the ryanodine receptor type 1 gene (RYR1). Recent genetic studies have shown that RYR1 variants are the most common cause of dominant and recessive congenital myopathies - central core and multi-minicore disease, congenital fiber type disproportion, and centronuclear myopathy. However, the MH status of many patients, especially with recessive RYR1-related myopathies, remains uncertain. We report the occurrence of a triplet of RYR1 variants, c.4711A>G (p.Ile1571Val), c.10097G>A (p.Arg3366His), c.11798A>G (p.Tyr3933Cys), found in cis in four unrelated families, one from Belgium, one from The Netherlands and two from Canada. Phenotype-genotype correlation analysis indicates that the presence of the triplet allele alone confers susceptibility to MH, and that the presence of this allele in a compound heterozygous state with the MH-associated RYR1 variant c.14545G>A (p.Val4849Ile) results in the MH susceptibility phenotype and a congenital myopathy with cores and rods. Our study underlines the notion that assigning pathogenicity to individual RYR1 variants or combination of variants, and counseling in RYR1-related myopathies may require integration of clinical, histopathological, in vitro contracture testing, MRI and genetic findings.

[Intracellular localization, isolation and characteristics of superoxide dismutase from Propionibacterium globosum]. / Vnutrikletochnaia lokalizatsiia, vydelenie i kharakteristika superoksiddismutazy iz Propionibacterium globosum.

From Propionibacterium globosum, superoxide dismutase (superoxide: superoxide dismutase, EC 1.15.1.1) has been isolated. As shown by polyacrylamide gel electrophoresis in native and denaturation conditions, the enzyme is a homogeneous protein with a specific activity of 3300 units/mg. In native conditions the enzyme molecular mass is 45,000 as measured by gel-filtration, and 22,000 as determined by Na-dodecyl sulphate electrophoresis. The enzyme is thermostable with pH optimum at 6.1-7.5. It has been found that superoxide dismutase of P. globosum is a membrane-independent cytoplasmic protein.

[Effect of technical threonine sources on homoserine biosynthesis by mutant Brevibacteruim flavum 2T]. / Vliianie tekhnicheskikh istochnikov treonina na biosintez gomoserina mutantom Brevibacterium flavum T 2T.

The effect of threonine technical sources on the homoserine biosynthesis by the threonine auxotroph Brevibacterium flavum 2T when cultivated on sucrose and acetic acid containing media was investigated. Various threonine sources (corn extract and fodder yeast, microbial biomass and soybean meal hydrolyzates) prepared by means of different hydrolyzing agents (acids, enzymes, autolysis) were used. The most effective substrate was protein--vitamin concentrate hydrolyzate, particularly combined with corn extract in the ratio 1: 0,25-0.5 (with respect to the dry weight of the initial material). The homoserine yield was 16.2 g/l on the sucrose containing medium and 18.4 g/l on the acetic acid containing medium which was in agreement with controls. The medium containing pure threonine was used as a control. With other threonine sources (corn extract, protein-vitamin concentrate autolyzate and enzymolyzate, fodder yeast and soybean meal hydrolyzates), the homoserine production was significantly lower, i.e. 40-70% of the control. The content of amino acids (threonine, isoleucine, methionine) in the initial material and their suitability for the homoserine biosynthesis were found to be correlated. The substrates with a high content of threonine (over 3.5%) and a low content of methionine (below 0.5%) proved most effective. The use of the material in which the ratio threonine: methionine was less than 6.0 caused the homoserine biosynthesis to be partially replaced with that of lysine.

[Estimation of chemical composition of molasses for leucine biosynthesis by the methods of statistical analysis]. / Otsenka khimicheskogo sostava melassy dlia biosinteza leitsina metodami statitsticheskogo analiza.

Chemical composition of molasses, used as sources of carbohydrates for leucine biosynthesis has been studied. Influence of molasses parameters on biomass growth and leucine synthesis in the process of cultivation of the producer of Corynebacterium sp. genus is proved. The results are processed by the personal computer with the use of applied statistical programs. The limits of changes of molasses parameters, allowing one to obtain 19.0-21.2 g/l leucine at the level of carbohydrate conversion of 19.4-21.8 %, have been determined.

[Superoxide dismutase, catalase and peroxidase of propionic acid bacteria]. / [Superoksiddismutaza, katalaza i peroksidaza propionovokislykh bakterii.

The respiration of different species of propionic acid bacteria was found to be resistant to the inhibiting action of cyanide. Propionibacterium globosum, P. globosum (emm), P. vannielii, P. shermanii, P. petersonii, P. pentosaceum and P. raffinosaceum were shown to contain superoxide dismutase, catalase and peroxidase. The highest activity of catalase and superoxide dismutase was found in P. globosum and P. vannielii, the lowest one in P. shermanii and P. raffinosaceum. Peroxidase was detected in propionic bacteria for the first time.

[Propionic acid cocci and their taxonomic position]. / Propionovokislye kokki i ikh sistematicheskoe polozhenie.

In order to determine the taxonomic position of propionic cocci, the authors studied their morphological, cultural and biochemical properties, the fatty acid composition of cells, and established the degree of homology for the DNAs of cocci and classical propionic bacteria using the method of molecular hybridization. The cocci were found to have the activities of catalase and superoxide dismutase which were higher than in the studied propionic bacteria. The propionic cocci and propionic bacteria were shown to be similar in terms of their fatty acid composition and to contain the C15-saturated acid in the form of anteiso isomer as the main type of fatty acids. Their fatty acid composition was most similar to that of the species Propionibacterium jensenii (P. technicum). The propionic cocci and bacteria are related in the structure of their genomes, particularly, in the case of the bacterium P. jensenii (P. raffinosaceum)--49%. On the basis of studying the phenotypic characteristics, the fatty acid composition, the nucleotide composition of DNA, and the high degree of homology between the DNAs of the cocci and the bacterial species P. jensenii (P. raffinosaceum), the authors propose to assign the cocci to the genus Propionibacterium as a new species Propionibacterium coccoides.

[n-Alkane oxidation by propionic acid bacteria]. / Okislenie n-alkanov propionovokislymi bakteriiami.

Propionic acid bacteria were found for the first time to be capable of oxidizing n-alkanes. The value of QO2 is higher on a mixture of n-alkanes (C12--C20) than on individual hydrocarbons whose availability is determined by the length of a hydrocarbon chain: C15 and C16-alkanes are oxidized best of all; C14, C13 and C12-alkanes are oxidized at a lower rate; and alkanes whose chain comprises less than ten carbon atoms are not oxidized at all. Hexadecane is oxidized to CO2, cetyl alcohol and palmitic acid being intermediates; this suggests the existence of the monoterminal pathway for oxidation of n-alkanes in propionic acid bacteria.

[Peroxidase of propionic acid bacteria]. / Peroksidaza propionovokislykh bakterii.

The peroxidase activity was found in Propionibacterium shermanii. Methods were developed to isolate and purify the enzyme. It was shown to be a heme-containing protein, specific to H2O2, stable at 20 to 30 degrees C and exerting the optimal action at pH 6.8 to 7.0. The rate of the enzyme-catalysed reaction was studied as a function of the enzyme and substrate concentrations. The Km was determined for H2O2 and o-dianisidine.