Link between packing morphology and the distribution of contact forces and stresses in packings of highly nonconvex particles

An external load on a particle packing is distributed internally through a heterogeneous network of particle contacts. This contact force distribution determines the stability of the particle packing and the resulting structure. Here, we investigate the homogeneity of the contact force distribution in packings of highly nonconvex particles both in two-dimensional (2D) and three-dimensional (3D) packings. A recently developed discrete element method is used to model packings of nonconvex particles of varying sphericity. Our results establish that in 3D packings the distribution of the contact forces in the normal direction becomes increasingly heterogeneous with decreasing particle sphericity. However, in 2D packings the contact force distribution is independent of particle sphericity, indicating that results obtained in 2D packings cannot be extrapolated readily to 3D packings. Radial distribution functions show that the crystallinity in 3D packings decreases with decreasing particle sphericity. We link the decreasing homogeneity of the contact force distributions to the decreasing crystallinity of 3D packings. These findings are complementary to the previously observed link between the heterogeneity of the contact force distribution and a decreasing packing crystallinity due to an increasing polydispersity of spherical particles.

EAU-ESMO consensus statements on the management of advanced and variant bladder cancer-an international collaborative multi-stakeholder effort: under the auspices of the EAU and ESMO Guidelines Committees†

BACKGROUND

Although guidelines exist for advanced and variant bladder cancer management, evidence is limited/conflicting in some areas and the optimal approach remains controversial.

OBJECTIVE

To bring together a large multidisciplinary group of experts to develop consensus statements on controversial topics in bladder cancer management.

DESIGN

A steering committee compiled proposed statements regarding advanced and variant bladder cancer management which were assessed by 113 experts in a Delphi survey. Statements not reaching consensus were reviewed; those prioritised were revised by a panel of 45 experts before voting during a consensus conference.

SETTING

Online Delphi survey and consensus conference.

PARTICIPANTS

The European Association of Urology (EAU), the European Society for Medical Oncology (ESMO), experts in bladder cancer management.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Statements were ranked by experts according to their level of agreement: 1-3 (disagree), 4-6 (equivocal), 7-9 (agree). A priori (level 1) consensus was defined as ≥70% agreement and ≤15% disagreement, or vice versa. In the Delphi survey, a second analysis was restricted to stakeholder group(s) considered to have adequate expertise relating to each statement (to achieve level 2 consensus).

RESULTS AND LIMITATIONS

Overall, 116 statements were included in the Delphi survey. Of these, 33 (28%) statements achieved level 1 consensus and 49 (42%) statements achieved level 1 or 2 consensus. At the consensus conference, 22 of 27 (81%) statements achieved consensus. These consensus statements provide further guidance across a broad range of topics, including the management of variant histologies, the role/limitations of prognostic biomarkers in clinical decision making, bladder preservation strategies, modern radiotherapy techniques, the management of oligometastatic disease and the evolving role of checkpoint inhibitor therapy in metastatic disease.

CONCLUSIONS

These consensus statements provide further guidance on controversial topics in advanced and variant bladder cancer management until a time where further evidence is available to guide our approach.

Mutational spectrum and deep intronic variants in the factor VIII gene of haemophilia A patients

Haemophilia A (HA) is caused by a broad spectrum of different mutation types in the factor VIII gene (F8). In our patient cohort of more than 2600 HA patients as well as in other published studies, the most frequent cause are missense mutations in different F8 exons or the recurrent intron 22 inversion. Some exons and several specific nucleotide positions represent hot spots for point mutations in the examined cohort. About 4 % of cases remain without mutation after routine HA diagnostic methods including inversion PCRs, Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA). Deep intronic mutations cannot be detected by current standard HA diagnostics but have been reported for several genetic disorders. However, next generation sequencing (NGS) of the whole genomic sequence of the F8 gene allows to identify deep intronic variants. Conclusion: In general, NGS provides an effective approach to screen for different HA causing mutation types in the F8 gene.

Unusual genomic rearrangements in introns 1 and 22 of the F8 gene

Intron 1 and intron 22 inversions, two large rearrangements of the factor VIII gene, are generally associated with a severe phenotype of haemophilia A and a high risk of inhibitor formation. In several haemophiliacs, diagnostic analyses for detection of these inversions revealed unusual band patterns. Upon further examination, different copy number variations were detected in the factor VIII gene of these patients by multiplex ligationdependent probe amplification (MLPA). Since these duplications or deletions alone could not sufficiently explain the abnormal band patterns of the first analyses, we assumed a combination of intron 1 or intron 22 inversions together with a copy number variation.

Result We could confirm this hypothesis by specific long range PCRs but a detailed characterization of the breakpoints and the mechanisms for these complex rearrangements have yet to be elucidated.

Mutational spectrum and deep intronic variants in the factor VIII gene of haemophilia A patients. Identification by next generation sequencing

Haemophilia A (HA) is caused by a broad spectrum of different mutation types in the factor VIII gene (F8). In our patient cohort of more than 2600 HA patients as well as in other published studies, the most frequent cause are missense mutations in different F8 exons or the recurrent intron 22 inversion. Some exons and several specific nucleotide positions represent hot spots for point mutations in the examined cohort. About 4 % of cases remain without mutation after routine HA diagnostic methods including inversion PCRs, Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA). Deep intronic mutations cannot be detected by current standard HA diagnostics but have been reported for several genetic disorders. However, next generation sequencing (NGS) of the whole genomic sequence of the F8 gene allows to identify deep intronic variants.

CONCLUSION

In general, NGS provides an effective approach to screen for different HA causing mutation types in the F8 gene.

Evading Vacuum Noise: Wigner Projections or Husimi Samples?

The accuracy in determining the quantum state of a system depends on the type of measurement performed. Homodyne and heterodyne detection are the two main schemes in continuous-variable quantum information. The former leads to a direct reconstruction of the Wigner function of the state, whereas the latter samples its Husimi Q function. We experimentally demonstrate that heterodyne detection outperforms homodyne detection for almost all Gaussian states, the details of which depend on the squeezing strength and thermal noise.

A comparative reference study for the validation of HLA-matching algorithms in the search for allogeneic hematopoietic stem cell donors and cord blood units

The accuracy of human leukocyte antigen (HLA)‐matching algorithms is a prerequisite for the correct and efficient identification of optimal unrelated donors for patients requiring hematopoietic stem cell transplantation. The goal of this World Marrow Donor Association study was to validate established matching algorithms from different international donor registries by challenging them with simulated input data and subsequently comparing the output. This experiment addressed three specific aspects of HLA matching using different data sets for tasks of increasing complexity. The first two tasks targeted the traditional matching approach identifying discrepancies between patient and donor HLA genotypes by counting antigen and allele differences. Contemporary matching procedures predicting the probability for HLA identity using haplotype frequencies were addressed by the third task. In each task, the identified disparities between the results of the participating computer programs were analyzed, classified and quantified. This study led to a deep understanding of the algorithms participating and finally produced virtually identical results. The unresolved discrepancies total to less than 1%, 4% and 2% for the three tasks and are mostly because of individual decisions in the design of the programs. Based on these findings, reference results for the three input data sets were compiled that can be used to validate future matching algorithms and thus improve the quality of the global donor search process.

Na+ doping induced changes in the reduction and charge transport characteristics of Al2O3-stabilized, CuO-based materials for CO2 capture

We report on the influence of Na⁺ doping on the local structure, electronic properties and cyclic redox characteristics of alumina-stabilized copper oxide based materials for chemical looping combustion based CO₂ capture architectures.

Malignant hyperthermia, a Scandinavian update

BACKGROUND

Malignant Hyperthermia (MH) is a rare pharmacogenetic disorder, triggered by halogenated anesthetics and/or succinylcholine. In susceptible individuals, these drugs can activate an explosive life threatening clinical reaction. Leading symptoms are hypercarbia, muscle rigidity, and metabolic acidosis. MH is inherited in an autosomal-dominant manner and linked to mutations in the large ryanodine 1 gene (RYR1) gene in the majority of cases. Very few MH patients have been found to carry mutations in the CACNA1S gene.

METHODS

For this review a large litterature search was carried out and the Swedish MH database consisting of 436 probands who have undergone in vitro muscle contraction test (IVCT) during 1984-2014 was analyzed.

RESULTS

Twelve different MH causative mutations have been found in Swedish patients so far. These mutations lead to a disturbed calcium balance in striated muscle tissue. A muscle biopsy for the IVCT or finding of an approved causative mutation are required for the diagnosis.

CONCLUSION

A Malignant Hyperthermia susceptible (MHS) patient should be anesthetized with trigger-free anesthesia. There are a few reports of MH-like reactions in patients unrelated to anesthesia. The outcome is dependent on early recognizing of the reaction and fast disconnection of the trigger agents and administration of dantrolene.

Next-generation DNA sequencing of a Swedish malignant hyperthermia cohort

Malignant hyperthermia (MH)-related mutations have been identified in the ryanodine receptor type 1 gene (RYR1) and in the dihydropyridine gene (CACNA1S), but about half of the patients do not have causative mutations in these genes. We wanted to study the contribution of other muscle genes to the RYR1 phenotypes. We designed a gene panel for sequence enrichment targeting 64 genes of proteins involved in the homeostasis of the striated muscle cell. Next-generation sequencing (NGS) resulted in >50,000 sequence variants which were further analyzed by software filtering criteria to identify causative variants. In four of five patients we identified previously reported RYR1 mutations while the fifth patient did not show any candidate variant in any of the genes investigated. In two patients pathogenic variants were found in other genes known to cause a muscle disorders. All but one patient carried likely benign rare polymorphisms. The NGS technique proved convenient in identifying variants in the RYR1. However, with a clinically variable phenotype-like MH, the pre-selection of genes poses problems in variant interpretation.

Comparative validation of computer programs for haplotype frequency estimation from donor registry data

Estimation of human leukocyte antigen (HLA) haplotype frequencies from unrelated stem cell donor registries presents a challenge because of large sample sizes and heterogeneity of HLA typing data. For the 14th International HLA and Immunogenetics Workshop, five bioinformatics groups initiated the 'Registry Diversity Component' aiming to cross-validate and improve current haplotype estimation tools. Five datasets were derived from different donor registries and then used as input for five different computer programs for haplotype frequency estimation. Because of issues related to heterogeneity and complexity of HLA typing data identified in the initial phase, the same five implementations, and two new ones, were used on simulated datasets in a controlled experiment where the correct results were known a priori. These datasets contained various fractions of missing HLA-DR modeled after European haplotype frequencies. We measured the contribution of sampling fluctuation and estimation error to the deviation of the frequencies from their true values, finding equivalent contributions of each for the chosen samples. Because of patient-directed activities, selective prospective typing strategies and the variety and evolution of typing technology, some donors have more complete and better HLA data. In this setting, we show that restricting estimation to fully typed individuals introduces biases that could be overcome by including all donors in frequency estimation. Our study underlines the importance of critical review and validation of tools in registry-related activity and provides a sustainable framework for validating the computational tools used. Accurate frequencies are essential for match prediction to improve registry operations and to help more patients identify suitably matched donors.

Comparative genetics of warfarin resistance

Warfarin and other 4-hydroxycoumarin-based oral anticoagulants targeting vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) are administered to humans, mice and rats with different purposes in mind - to act as pesticides in high-dosage baits for killing rodents, but also to save lives when administered in low dosages as antithrombotic drugs in humans. However, high-dosage warfarin used to control rodent populations has resulted in numerous mutations causing warfarin resistance. Currently, six single missense mutations in mice, 12 distinct missense mutations in rats, as well as compound heterozygous or homozygous mutations with up to six distinct missense mutations per Vkorc1 allele have been described. Warfarin resistance missense mutations for human VKORC1 have also been found world-wide, but differ characteristically from those in rodents. In humans, 26 distinct mutations have been characterized, but occur only rarely either in heterozygous or, even rarer, in homozygous form. In this review, we summarize the known VKORC1 missense mutations causing warfarin and other 4-hydroxycoumarin drug resistance, identify genomics databases as new sources of data, explore possible underlying genetic mechanisms, and summarize similarities and differences between warfarin resistant VKORC1 variants in humans and rodents.

Common and well-documented HLA alleles: 2012 update to the CWD catalogue

We have updated the catalogue of common and well-documented (CWD) human leukocyte antigen (HLA) alleles to reflect current understanding of the prevalence of specific allele sequences. The original CWD catalogue designated 721 alleles at the HLA-A, -B, -C, -DRB1, -DRB3/4/5, -DQA1, -DQB1, and -DPB1 loci in IMGT (IMmunoGeneTics)/HLA Database release 2.15.0 as being CWD. The updated CWD catalogue designates 1122 alleles at the HLA-A, -B, -C, -DRB1, -DRB3/4/5, -DQA1, -DQB1, -DPA1 and -DPB1 loci as being CWD, and represents 14.3% of the HLA alleles in IMGT/HLA Database release 3.9.0. In particular, we identified 415 of these alleles as being 'common' (having known frequencies) and 707 as being 'well-documented' on the basis of ~140,000 sequence-based typing observations and available HLA haplotype data. Using these allele prevalence data, we have also assigned CWD status to specific G and P designations. We identified 147/151 G groups and 290/415 P groups as being CWD. The CWD catalogue will be updated on a regular basis moving forward, and will incorporate changes to the IMGT/HLA Database as well as empirical data from the histocompatibility and immunogenetics community. This version 2.0.0 of the CWD catalogue is available online at cwd.immunogenomics.org, and will be integrated into the Allele Frequencies Net Database, the IMGT/HLA Database and National Marrow Donor Program's bioinformatics web pages.

An update to the HLA Nomenclature Guidelines of the World Marrow Donor Association, 2012

For more than two decades, international cooperation and information technology have been playing key roles in the identification of suitable unrelated donors and cord blood units for hematopoietic SCT. To ensure consistent coding and interpretation of HLA data among the linked computer systems, the World Marrow Donor Association has standardized the extensions of the World Health Organization (WHO) Nomenclature for factors of the HLA system applied in practice. The first version of this report published in 2007 has become the reference for the technical validation of HLA information on donors and patients in the context of search and matching and is used by registries of volunteer unrelated hematopoietic stem cell donors and umbilical cord blood banks throughout the world. The present update became necessary after the major revision of the WHO HLA nomenclature in April 2010. It now covers issues arising when alleles are withdrawn or renamed because of the continuous updating of the WHO HLA nomenclature. In addition, formal validation and interpretation rules for the so-called 'multiple allele codes' have been added.

A new cell culture-based assay quantifies vitamin K 2,3-epoxide reductase complex subunit 1 function and reveals warfarin resistance phenotypes not shown by the dithiothreitol-driven VKOR assay

BACKGROUND

Warfarin directly inhibits the vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) enzyme to effect anticoagulation. VKORC1 function has historically been assessed in vitro using a dithiothreitol (DTT)-driven vitamin K 2,3-epoxide reductase (VKOR) assay. Warfarin inhibits wild-type VKORC1 function by the DTT-VKOR assay. However, VKORC1 variants with warfarin resistance-associated missense mutations often show low VKOR activities and warfarin sensitivity instead of resistance.

OBJECTIVES

A cell culture-based, indirect VKOR assay was developed and characterized that accurately reports warfarin sensitivity or resistance for wild-type and variant VKORC1 proteins.

METHODS

Human coagulation factor (F)IX and VKORC1 variants were coexpressed in HEK 293T cells under standardized conditions at various warfarin concentrations. Secreted FIX activity served as surrogate marker to report wild-type and variant VKORC1 inhibition by warfarin.

RESULTS AND CONCLUSIONS

Warfarin dose-response curves fit to the secreted FIX activity data for coexpressed hVKORC1 wild-type, Val29Leu, Val45Ala and Leu128Arg variants. The corresponding calculated IC50 values were 24.7, 136.4, 152.0 and 1226.4 nm, respectively. Basal activities in the absence of warfarin for all VKORC1 variants were similar to that of wild-type VKORC1. Ranked IC50 values from the cell culture-based assay accurately reflect elevated warfarin dosages for patients with VKORC1 missense mutation-associated warfarin resistance.

Is axial dispersion within rotating cylinders governed by the Froude number?

Axial dispersion rates of particles within horizontal rotating cylinders have been calculated for a decade of cylinder diameters. Throughout the range studied the rate of axial dispersion was found to be independent of the cylinder diameter. This phenomenon has been investigated further by spatially resolving the local contribution to the axial dispersion coefficient. This analysis demonstrates that, although the highest rates of axial dispersion occur at the free surface of the bed, there is a significant contribution to axial dispersion throughout the flowing region of the bed. Finally, based on an analogy with a Galton board, a linear relationship is proposed between the local rate of axial dispersion within a horizontal rotating cylinder and the product of the local particle concentration and the local shear rate in a plane perpendicular to the cylinder axis.

Methylation analysis of the promoter region and intron 1 of the factor VIII gene in haemophilia A patients

Methylation, CpG island, promoter, intron 1 Haemophilia A is the most common X-linked inherited coagulation disorder caused by a deficiency of the factor VIII protein (FVIII). A plethora of different mutations in the factor VIII gene (F8) have been identified as causative for this bleeding disease including a few promoter mutations. However, in approximately 2-5% of all haemophilic patients, the causal mutation still remains unknown. To our knowledge, epigenetic abnormalities in regulatory regions of the F8 gene have not yet been implicated in the disease pathogenesis. We therefore developed bisulfite pyrosequencing assays to screen patients with unknown mutation status for their methylation patterns in presumed regulative regions of the F8 gene (5'UTR and intron 1). The methylation patterns of haemophilia A patients did not differ from that of controls. In three patients, chromosomal aberrations were identified which could be associated with a defective FVIII synthesis.

Methylation analysis of the promoter region and intron 1 of the factor VIII gene in haemophilia A patients

Haemophilia A is the most common X-linked inherited coagulation disorder caused by a deficiency of the factor VIII protein (FVIII). A plethora of different mutations in the factor VIII gene (F8) have been identified as causative for this bleeding disease including a few promoter mutations. However, in approximately 2–5% of all haemophilic patients, the causal mutation still remains unknown. To our knowledge, epigenetic abnormalities in regulatory regions of the F8 gene have not yet been implicated in the disease pathogenesis.

We therefore developed bisulfite pyrosequencing assays to screen patients with unknown mutation status for their methylation patterns in presumed regulative regions of the F8 gene (5’UTR and intron 1). The methylation patterns of haemophilia A patients did not differ from that of controls. In three patients, chromosomal aberrations were identified which could be associated with a defective FVIII synthesis.

On the occurrence of polygon-shaped patterns in vibrated cylindrical granular beds

We report experimental observations of polygon-shaped patterns formed in a vertically vibrated bed of circular cross-section. A phase map is determined, showing that the polygon pattern is established for Γ = A(2πf)(2)/g is > or approximately equal to 10. The sensitivity of the polygon structure to bed parameters was tested by studying beds of different particle sizes and fill levels. It was hypothesized that the polygon pattern observed in cylindrical beds is the corresponding pattern to the formation of arches in square-shaped beds. The close relationship between these two patterns was demonstrated by two observations: i) the radii of the arches of a corresponding square bed and the inner radius of the cylindrical bed were found to be very similar and ii) the boundary lengths of the two patterns were in good agreement.

Unusual genomic rearrangements in introns 1 and 22 of the F8 gene

Intron 1 and intron 22 inversions, two large rearrangements of the factor VIII gene, are generally associated with a severe phenotype of haemophilia A and a high risk of inhibitor formation. In several haemophiliacs, diagnostic analyses for detection of these inversions revealed unusual band patterns. Upon further examination, different copy number variations were detected in the factor VIII gene of these patients by multiplex ligation-dependent probe amplification (MLPA). Since these duplications or deletions alone could not sufficiently explain the abnormal band patterns of the first analyses, we assumed a combination of intron 1 or intron 22 inversions together with a copy number variation.

RESULT

We could confirm this hypothesis by specific long range PCRs but a detailed characterization of the breakpoints and the mechanisms for these complex rearrangements have yet to be elucidated.

Axial transport within bidisperse granular media in horizontal rotating cylinders

The discrete element method has been used to examine axial dispersion within rotating cylinders containing two sizes of particle. Two bed configurations are considered: initially segregated, which consists of a pulse (narrow axial band) of small particles within a bed of large particles, and initially mixed, in which the cylinder is loaded with a homogeneous mixture of the two particle sizes. The dispersion of the small particles within initially segregated beds is found to depend strongly on the initial length of the pulse of small particles. Initially mixed beds are found to undergo a transient period in which the small particles disperse rapidly. Following this transient, axial dispersion of both particles sizes is found to follow Fick's second law, in that the mean squared deviation of the axial position of the particles is proportional to time. Axial dispersion coefficients have been calculated for initially mixed beds that have reached steady state; the axial dispersion coefficients of both particle sizes decrease as the volume fraction of small particles is increased.

Thirteen novel VKORC1 mutations associated with oral anticoagulant resistance: insights into improved patient diagnosis and treatment

BACKGROUND

Vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) is the molecular target of oral anticoagulants. Mutations in VKORC1 cause partial or total coumarin resistance.

OBJECTIVES

To identify new VKORC1 oral anticoagulant (OAC) resistance (OACR) mutations and compare the severity of patient phenotypes across different mutations and prescribed OAC drugs.

PATIENTS/METHODS

Six hundred and twenty-six individuals exhibiting partial or complete coumarin resistance were analyzed by VKORC1 gene sequencing and CYP2C9 haplotyping.

RESULTS

We identified 13 patients, each with a different, novel human VKORC1 heterozygous mutation associated with an OACR phenotype. These mutations result in amino acid substitutions: Ala26→Thr, His28→Gln, Asp36→Gly, Ser52→Trp, Ser56→Phe, Trp59→Leu, Trp59→Cys, Val66→Gly, Gly71→Ala, Asn77→Ser, Asn77→Tyr, Ile123→Asn, and Tyr139→His. Ten additional patients each had one of three previously reported VKORC1 mutations (Val29→Leu, Asp36→Tyr, and Val66→Met). Genotyping of frequent VKORC1 and CYP2C9 polymorphisms in these patients revealed a predominant association with combined non-VKORC1*2 and wild-type CYP2C9 haplotypes. Additionally, data for OAC dosage and the associated measured International Normalized Ratio (INR) demonstrate that OAC therapy is often discontinued by physicians, although stable therapeutic INR levels may be reached at higher OAC dosages. Bioinformatic analysis of VKORC1 homologous protein sequences indicated that most mutations cluster into protein sequence segments predicted to be localized in the lumenal loop or at the endoplasmic reticulum membrane-lumen interface.

CONCLUSIONS

OACR mutations of VKORC1 predispose afflicted patients to high OAC dosage requirements, for which stable, therapeutic INRs can sometimes be attained.

Characterization of duplication breakpoints in the factor VIII gene

BACKGROUND

Hemophilia A is caused by a wide spectrum of different mutations in the factor (F)VIII gene (F8), leading to deficiencies in coagulation FVIII activity and thus resulting in an inefficient blood clotting cascade. Large duplications comprising whole exons of F8 have been published for only a few cases so far.

RESULTS

In the current study, we characterized the exact breakpoints for a total of 10 exon-spanning duplications of F8, including six novel duplications in seven unrelated patients. Seven breakpoints were located within long interspersed nuclear elements (LINEs), whereas short interspersed nuclear elements (SINEs) of the Alu-repeat type were observed at both breakpoint sites in four of the 10 duplications. At three breakpoints, microhomologies of 2 bp and 3 bp each could be identified.

CONCLUSIONS

Duplication breakpoints in F8 were shown to be located in repetitive elements, especially SINEs or LINEs, but also in unique sequences. In addition, microhomologies, particular genomic features or sequence motifs, contribute to the duplication formation mechanisms.

RYR1 mutations are a common cause of congenital myopathies with central nuclei

OBJECTIVE

Centronuclear myopathy (CNM) is a rare congenital myopathy characterized by prominence of central nuclei on muscle biopsy. CNM has been associated with mutations in MTM1, DNM2, and BIN1 but many cases remain genetically unresolved. RYR1 encodes the principal sarcoplasmic reticulum calcium release channel and has been implicated in various congenital myopathies. We investigated whether RYR1 mutations cause CNM.

METHODS

We sequenced the entire RYR1 coding sequence in 24 patients with a diagnosis of CNM from South Africa (n = 14) and Europe (n = 10) and identified mutations in 17 patients. The most common genotypes featured compound heterozygosity for RYR1 missense mutations and mutations resulting in reduced protein expression, including intronic splice site and frameshift mutations.

RESULTS

The high incidence in South African patients (n = 12/14) in conjunction with recurrent RYR1 mutations associated with common haplotypes suggested the presence of founder effects. In addition to central nuclei, prominent histopathological findings included (often multiple) internalized nuclei and type 1 fiber predominance and hypotrophy with relative type 2 hypertrophy. Although cores were not typically seen on oxidative stains, electron microscopy revealed subtle abnormalities in most cases. External ophthalmoplegia, proximal weakness, and bulbar involvement were prominent clinical findings.

INTERPRETATION

Our findings expand the range of RYR1-related phenotypes and suggest RYR1 mutations as a common cause of congenital myopathies with central nuclei. Corresponding to recent observations in X-linked CNM, these findings indicate disturbed assembly and/or malfunction of the excitation-contraction machinery as a key mechanism in CNM and related myopathies.

Magnetic resonance measurements of high-velocity particle motion in a three-dimensional gas-solid spouted bed

Magnetic resonance imaging has been used to measure particle velocities, exceeding 1 m s⁻¹ in a two-phase granular system, namely, a spouted bed. The measurements are complicated due to the high voidage, i.e., low particle density, in the region of the highest particle velocity. However, applying gradient shapes which allow fast switching and, thus, short encoding and observation times in combination with a short echo time enable these measurements. It was found that the profile of the particle velocity is nonparabolic. Based on these measurements it was possible to confirm observations made in numerical simulations that there must be a continuous momentum exchange between the annulus region and the spout along the entire length of the spout.

Recognizing and managing a malignant hyperthermia crisis: guidelines from the European Malignant Hyperthermia Group

Survival from a malignant hyperthermia (MH) crisis is highly dependent on early recognition and prompt action. MH crises are very rare and an increasing use of total i.v. anaesthesia is likely to make it even rarer, leading to the potential risk of reduced awareness of MH. In addition, dantrolene, the cornerstone of successful MH treatment, is unavailable in large areas around the world thereby increasing the risk of MH fatalities in these areas. The European Malignant Hyperthermia Group collected and reviewed all guidelines available from the various MH centres in order to provide a consensus document. The guidelines consist of two textboxes: Box 1 on recognizing MH and Box 2 on the treatment of an MH crisis.

Mutation screening of the RYR1-cDNA from peripheral B-lymphocytes in 15 Swedish malignant hyperthermia index cases

BACKGROUND

Malignant hyperthermia (MH), linked to the ryanodine receptor 1 gene (RYR1) on chromosome 19, is a potentially lethal pharmacogenetic disorder which may lead to a disturbance of intracellular calcium homeostasis when susceptible individuals are exposed to halogenated anaesthetics, suxamethonium, or both. Central core disease (CCD) is a rare dominantly inherited congenital myopathy allelic to MH-susceptibility.

METHODS

In this study, 14 unrelated MH-susceptible probands and one CCD patient from Sweden were screened for mutations in the RYR1. Since the RYR1 is also expressed in B-lymphocytes, RYR1-cDNA was transcribed from total RNA extracted from white blood cells.

RESULTS

We detected two known RYR1 mutations and two previously described unclassified sequence variants. In addition, six novel sequence variants were detected. All mutations or sequence variants were verified on genomic DNA. Seven of the probands did not show any candidate mutation, although the total coding region of RYR1 was sequenced. Segregation data in in vitro contracture tested family members of three probands support a causative role of three of the novel sequence variants.

CONCLUSIONS

Our study contributes to the genetic aetiology of MH in Sweden, but also raises questions about the involvement of genes other than RYR1 since nearly half of the probands did not show any sequence variants in the total coding region of the RYR1.

Phenotypic variability in siblings with calpainopathy (LGMD2A)

Calpainopathy is an autosomal-recessive limb girdle muscular dystrophy (LGMD2A) characterized by selective atrophy and weakness of proximal limb girdle muscles. The clinical phenotype of the disease is highly variable inter-familial, but little is known about intra-familial variability. This study reports the phenotypic variability in eight sibling pairs with genetically proven LGMD2A. Although siblings with identical mutations were often similarly affected, in some families the age of onset and the clinical course varied considerably.

Mutational spectrum of the C1INH (SERPING1) gene in patients with hereditary angioedema

Hereditary angioedema (HAE) is an autosomal dominant disease that manifests as intermittent acute swellings of the skin and mucosal surfaces, which, in the gastrointestinal tract and larynx, may even be fatal. HAE results from functional deficiency of the C1 inhibitor (C1INH) protein, which plays a key role in the classical pathway of complement activation. C1INH is the sole inhibitor of the activated proteases C1r and C1s, and is the major regulator of activated coagulation Factor XII and plasma kallikrein, which limits the generation of the vasoactive peptide bradykinin. In this paper, we report on the genetic analysis of 173 families (including 326 members) with a clinical diagnosis of HAE. Direct sequencing, Southern blotting and quantitative PCR by the MLPA method were used to screen for mutations in C1INH (SERPING1). In 142 families (82.1%), a causative C1INH gene mutation could be identified. A total of 80 novel point mutations of C1INH not published previously were detected in 96 pedigrees (including 172 members). Our results corroborate C1INH (SERPING1) deficiency as a disease of extreme allelic heterogeneity with almost each individual family carrying their own mutation. Routine molecular genetic analysis is an effective way of confirming the clinical diagnosis and identifying mutation carriers early on before any clinical manifestation becomes apparent. It is, therefore, a valuable tool in prevention and adequate treatment of acute and life-threatening oedema.