Switchable slow relaxation of magnetization in the native low temperature phase of a cooperative spin-crossover compound.

The implementation of single-molecule magnet properties in spin crossover materials is sought as a unique source of magnetic multistability at the molecular level. Examples however remain extremely scarce, in part due to the diamagnetic state of most Fe(ii) spin crossover materials at low temperatures. We have studied the complex [Fe(mtz)6](CF3SO3)2 (mtz = 1-methyltetrazole) as a tantalizing candidate of such coexistence, due to its known partial spin crossover and therefore paramagnetic native low temperature phase. The single-crystal structures of [Fe(mtz)6](CF3SO3)2 reported here allow rationalizing its peculiar cooperative spin-crossover behavior. Importantly, the high-spin Fe crystallographic sites at low temperature exhibit a high symmetry with a local trigonal distortion, usually source of magnetic anisotropy. The analysis of equilibrium magnetic properties confirm the presence of a significant magnetic anisotropy at the Fe(ii) high spin sites in the high symmetry low temperature phase. This results in field-induced slow relaxation of their magnetization which is dominated at low temperature by tunneling and direct processes and is strongly enhanced above 3 K by Raman and Orbach processes. Unprecedentedly, these single-molecule magnet properties are observed in the native ground state of a spin crossover material and efficiently and reversibly switched OFF through visible light irradiation.

A diffusive ink transport model for lipid dip-pen nanolithography.

Despite diverse applications, phospholipid membrane stacks generated by dip-pen nanolithography (DPN) still lack a thorough and systematic characterization that elucidates the whole ink transport process from writing to surface spreading, with the aim of better controlling the resulting feature size and resolution. We report a quantitative analysis and modeling of the dependence of lipid DPN features (area, height and volume) on dwell time and relative humidity. The ink flow rate increases with humidity in agreement with meniscus size growth, determining the overall feature size. The observed time dependence indicates the existence of a balance between surface spreading and the ink flow rate that promotes differences in concentration at the meniscus/substrate interface. Feature shape is controlled by the substrate surface energy. The results are analyzed within a modified model for the ink transport of diffusive inks. At any humidity the dependence of the area spread on the dwell time shows two diffusion regimes: at short dwell times growth is controlled by meniscus diffusion while at long dwell times surface diffusion governs the process. The critical point for the switch of regime depends on the humidity.

[Data validity in a French diagnosis-related group information program]. / Validité de la description d'un groupe spécifique de patients par le PMSI-SSR.

BACKGROUND: Long-term intratracheal ventilated patients need continuous artificial ventilation support. After the acute periods, these patients may benefit from dedicated follow-up in rehabilitation care centers. In this paper, we aimed to study the validity of the data provided by a French diagnosis-related group (DRG) information system. METHODS: For a sample of intratracheal ventilated patients in two rehabilitation units, we compared the data provided in the DRG information system with the data available in the medical charts. Furthermore, we asked the medical, nursing and allied health staff to assess the data provided by the French DRG information system. RESULTS: The diagnosis was found accurate for 86% of hospital stays. In the DRG information system, 77% of the medical care, and 39% of the nursing and allied health care were mentioned correctly. Overall, 55% of the nursing and allied health care procedures in the DRG information system were not reported in the medical charts. The healthcare providers estimated that the frequency of the care provided was underestimated in the DRG information system for 30% of the nursing and allied health care. CONCLUSION: The patients' main characteristics were found correctly reported in the DRG information system. However, the diversity and the frequency of the care provided were underestimated. These underestimates were mainly related to care frequently provided in these patients (for example, urinary catheterization, massages, counseling for relatives).

Self-assembled trityl radical capsules--implications for dynamic nuclear polarization.

A new class of guest-induced, bi-radical self-assembled organic capsules is reported. They are formed by the inclusion of a tetramethylammonium (TMA) cation between two monomers of the stable trityl radical OX63. OX63 is extensively used in dissolution dynamic nuclear polarization (DNP) where it leads to NMR sensitivity enhancements of several orders of magnitude. The supramolecular properties of OX63 have a strong impact on its DNP properties. An especially relevant case is the polarization of choline-containing metabolites, where complex formation between choline and OX63 results in faster relaxation.

Synthesis and magnetic behavior of ultra-small bimetallic FeCo/graphite nanoparticles.

FeCo-alloy graphite-coated nanoparticles with mean particle diameter under 8 nm have been synthesized following a CVD carbon-deficient method. The superior magnetic properties of FeCo-alloy nanoparticles makes them good candidates to be used as magnetic filler in magneto-polymer composites. Thanks to the protective effect of the graphite shell, FeCo nanoparticles are stable under oxygen atmosphere up to 200 ° C. The as-prepared nanoparticles presented a highly long range chemically ordered core being ferromagnetic at room temperature with a saturation magnetization at room temperature close to the bulk value. After annealing at 750 K the saturation magnetization and the coercive field increase. To investigate the processes involved in the thermal treatment, the temperature dependence of the magnetization and the particle composition, size and structure have been characterized before and after annealing. Besides powder x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS), a detailed study by means of advanced transmission electron microscopy (TEM) techniques has been carried out. In particular, aberration corrected scanning transmission electron microscopy (STEM), has shown that nanoparticles became faceted after the thermal treatment, as a mechanism to reach the thermodynamic equilibrium within the metastable phase. This outstanding feature, not previously reported, leads to an increase of the shape anisotropy, which in turn might be the origin of the observed increase of the coercive field after annealing.

Note: a sample holder design for sensitive magnetic measurements at high temperatures in a magnetic properties measurement system.

A sample holder design for high temperature measurements in a commercial MPMS SQUID magnetometer from Quantum Design is presented. It fulfills the requirements for the simultaneous use of the oven and reciprocating sample option (RSO) options, thus allowing sensitive magnetic measurements up to 800 K. Alternating current susceptibility can also be measured, since the holder does not induce any phase shift relative to the ac driven field. It is easily fabricated by twisting Constantan© wires into a braid nesting the sample inside. This design ensures that the sample be placed tightly into a tough holder with its orientation fixed, and prevents any sample displacement during the fast movements of the RSO transport, up to high temperatures.

Clinical, pathological and molecular findings in two siblings with giant axonal neuropathy (GAN): report from India.

BACKGROUND: Giant axonal neuropathy (GAN, MIM: 256850) is characterized by an early onset of severe peripheral neuropathy, varying central nervous system involvement and strikingly frizzly hair. Mode of inheritance is autosomal recessive. Mutations in the gigaxonin (GAN) gene on chromosome 16q24.1 are frequently observed for this disorder, but genetic heterogeneity has been demonstrated for a milder variant of GAN. Gigaxonin binds C-terminally to various microtubule associated proteins causing their ubiquitin-mediated degradation. For several gigaxonin mutations it was shown that they hamper this process resulting finally in accumulation of microtubule associated proteins which may disturb cellular functions. Here, we report a family originating in India with two patients showing typical clinical signs suggestive of GAN. METHODOLOGY: Genomic DNA was analyzed for both siblings and their parents in order to detect the molecular changes in the GAN gene. The complete coding region including flanking sequences was amplified using published primer sequences. The PCR products were sequenced on both strands after purification using an ABI 3730 (Applied Biosystems) capillary sequencer. The resulting sequences were evaluated using SeqPilot (JSI-medical systems GmbH) and were compared to the reference sequences (NT_024797, NM_022041) given in the NCBI-database. CONCLUSIONS: An AluYa5 insertion (c.1657ALUYa5ins, p.Thr553_Pro597del) in exon 11 of the GAN gene was identified homozygous in both siblings, whereas the parents were heterozygous carriers of this mutation. Here, the reported mutation is located in C-terminal part of the protein affecting the terminal kelch domain. Thus a functional important part of the protein is altered by the AluYa5 insertion and causes GAN.

Detection of common and private mutations in the COL6A1 gene of patients with Bethlem myopathy.

BACKGROUND: Dominant mutations in COL6A1, COL6A2, and COL6A3, the three genes encoding collagen type VI, a ubiquitous extracellular matrix protein, are associated with Bethlem myopathy (BM) and Ullrich scleroatonic muscular dystrophy. METHODS: The authors devised a method to screen the entire coding sequence of the three genes by reverse transcriptase-PCR amplification of total RNA from skin fibroblasts and direct sequencing of the resulting 25 overlapping cDNA fragments covering 107 exons. RESULTS: Four splicing and four missense mutations were identified in 16 patients with BM, six of which are novel mutations in COL6A1. Both common and private mutations are localized in the alpha1 (VI) chain between the regions corresponding to the 3' end of the NH2-globular domain and the 5' end of the triple helix, encoded by exons 3 through 14. CONCLUSIONS: The clustering of the mutations in a relatively narrow area of the three collagen type VI chains in patients with Bethlem myopathy (BM) suggests that mutations in different regions could result in different phenotypes or in no phenotype at all. Moreover, the detection of mutations in only 60% of the patients suggests the existence of at least another gene associated with BM. The authors propose the direct sequencing of COL6 cDNAs as the first mutation screening analysis in BM, given the high number of exon-skipping events.

Atypical findings in Kabuki syndrome: report of 8 patients in a series of 20 and review of the literature.

Kabuki syndrome (KS) is a rare multiple congenital anomaly/mental retardation syndrome with an estimated frequency of 1/32,000 in Japan. Five major criteria delineate KS namely postnatal short stature, skeletal anomalies, moderate mental retardation, dermatoglyphic anomalies, and a characteristic facial dysmorphism. Here we report on a series of 20 sporadic KS patients and we focus on some rare and atypical features that we have observed: chronic and/or severe diarrhea (4/20) including celiac disease, diaphragmatic defects (3/20), pseudarthrosis of the clavicles (2/20), vitiligo (2/20), and persistent hypoglycemia (2/20). Other occasional findings were severe autoimmune thrombopenia, cerebellar vermis atrophy, and myopathic features. Interestingly, one of our KS patients presented with a clinical overlap with CHARGE syndrome (right eye microphtalmia with optic nerve coloboma, VSD, bilateral cryptorchidism, and severe deafness). Because these features are more frequent in our series than previously described, we propose to carefully investigate these manifestations during KS patient survey in an attempt to determine their real frequency and in order to improve clinical management.

New autosomal recessive cerebellar ataxia disorder in a large inbred Lebanese family.

A large inbred Lebanese pedigree with congenital spastic ataxia, microcephaly, optic atrophy, short stature, speech defect, abnormal osmiophilic pattern of skin vessels, cerebellar atrophy, and severe mental retardation transmitted as an autosomal recessive trait has been studied. None of the children had any evidence of a metabolic disease, and the analysis of respiratory chain complex abnormalities was unremarkable. Only one child had a history of perinatal difficulties. Differential diagnosis and the possibility that this disorder is a hitherto unreported one are discussed.

Clinical and molecular genetic spectrum of autosomal dominant Emery-Dreifuss muscular dystrophy due to mutations of the lamin A/C gene.

Emery-Dreifuss muscular dystrophy (EDMD) is characterized by early contractures of the elbows and Achilles tendons, slowly progressive muscle wasting and weakness, and life-threatening cardiomyopathy with conduction blocks. We recently identified LMNA encoding two nuclear envelope proteins, lamins A and C, to be implicated in the autosomal dominant form of EDMD. Here, we report on the variability of the phenotype and spectrum of LMNA mutations in 53 autosomal dominant EDMD patients (36 members of 6 families and 17 sporadic cases). Twelve of the 53 patients showed cardiac involvement exclusively, although the remaining 41 all showed muscle weakness and contractures. We were able to identify a common phenotype among the patients with skeletal muscle involvement, consisting of humeroperoneal wasting and weakness, scapular winging, rigidity of the spine, and elbow and Achilles tendon contractures. The disease course was generally slow, but we observed either a milder phenotype characterized by late onset and a mild degree of weakness and contractures or a more severe phenotype with early presentation and a rapidly progressive course in a few cases. Mutation analysis identified 18 mutations in LMNA (i.e., 1 nonsense mutation, 2 deletions of a codon, and 15 missense mutations). All the mutations were distributed between exons 1 and 9 in the region of LMNA that is common to lamins A and C. LMNA mutations arose de novo in 76% of the cases; 2 of these de novo mutations were typical hot spots, and 2 others were identified in 2 unrelated cases. There was no clear correlation between the phenotype and type or localization of the mutations within the gene. Moreover, a marked inter- and intra-familial variability in the clinical expression of LMNA mutations exists, ranging from patients expressing the full clinical picture of EDMD to those characterized only by cardiac involvement, which points toward a significant role of possible modifier genes in the course of this disease. In conclusion, the high proportion of de novo mutations together with the large spectrum of both LMNA mutations and the expression of the disease should now prompt screening for LMNA in familial and sporadic cases of both EDMD and dilated cardiomyopathy associated with conduction system disease.

Brown-Vialetto-Van Laere syndrome in a large inbred Lebanese family: confirmation of autosomal recessive inheritance?

Brown-Vialetto-Van Laere syndrome or pontobulbar palsy with deafness is a rare disorder characterized by bilateral nerve deafness, a variety of cranial nerve disorders usually involving the motor components of the 7th and 9th to 12th cranial nerves, and less commonly an involvement of spinal motor nerves and upper motor neurons. Familial and sporadic cases have been reported. Based on particular evidence, autosomal recessive, autosomal dominant, and X-linked inheritance, as well as autoimmune origin have been considered. We report on a large inbred Lebanese family with four patients of both sexes, strongly suggesting autosomal recessive inheritance.

Homogeneous phenotype of the gypsy limb-girdle MD with the gamma-sarcoglycan C283Y mutation.

OBJECTIVE: To characterize the clinical phenotype of LGMD2C in gypsies. BACKGROUND: Limb-girdle muscular dystrophy (LGMD) in gypsies of Western Europe is caused by a homozygous C283Y mutation on the same haplotype, suggesting a founder effect. METHODS: We performed clinical, laboratory, and muscle imaging studies of 40 patients. RESULTS: Mean age at onset was 5.3 years. One half of the patients had loss of ambulation by the age of 12; 13% still could walk after age 16. Calf hypertrophy, scapular winging, macroglossia, and lumbar hyperlordosis were common. Girdle, trunk, and proximal limb flexor muscles had earlier and more severe involvement. Cardiomyopathy was not observed. Five patients in the third decade of life required mechanical ventilation. Scoliosis was common in the nonambulatory stage. CONCLUSIONS: LGMD2C in gypsy patients with C283Y mutation presents a rather homogeneous phenotype, characterized by an initial Duchenne-like progressive course followed by a more prolonged survival rate possibly due to the absence of early respiratory impairment and cardiac failure.

[Pathological anatomy of the heart in myopathies and infantile muscular atrophies]. / Anatomie pathologique du coeur dans les myopathies et amyotrophies spinales infantiles.

In progressive muscular dystrophy, the heart is always affected and presents characteristic histological lesions: irregular, diffuse and intense rearrangements predominantly in the left ventricle, the septum and conductive tissue, consisting of wide, poorly vascularized fibrous bands, that are destructive but without an inflammatory aspect. The remaining myocardium is dystrophic with degeneration of the fibers (hyalin, atrophic or hypertrophic) with irregular nuclei. Plaques of adipose tissue are found under the epicardium within the heart wall. Sometimes, a fibrous thickening of the intracoronary arteries is observed without modification of the intima, but vascular lesions are not systematically seen. In congenital muscular dystrophy, cardiomyopathy certainly exists, but there is no histological description. Half of the patients suffering from myopathy with intracytoplasmic inclusions also have dystrophic and fibrotic cardiac involvement. Congenital myopathies may have their own specific cardiomyopathy, as in central core myopathy, nemaline (rod) myopathy and especially myotubular myopathy, where involvement is common. Werdnig-Hoffmann disease types I and II do not affect the heart. In contrast, several cases of fibrotic lesions have been described in KugelbergWelander disease.