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Prague, Czech Republic

Zeman J.,Ke Karlovu
Developmental period medicine | Year: 2015

Mitochondrial disorders (MD) represent a clinically, biochemically and genetically heterogeneous group of diseases associated with dysfunction of the oxidative phosphorylation system and pyruvate dehydrogenase complex. Our aim was to illustrate the most common clinical presentation of MD on the example of selected diseases and syndromes. The minimal prevalence of MD is estimated as 1 to 5,000. MD may manifest at any age since birth until late-adulthood with acute manifestation or as a chronic progressive disease. Virtually any organ may be impaired, but the organs with the highest energetic demands are most frequently involved, including brain, muscle, heart and liver. Some MD may manifest as a characteristic cluster of clinical features (e.g. MELAS syndrome, Kearns-Sayre syndrome). Diagnostics includes detailed history, the comprehensive clinical examination, results of specialized examinations (especially cardiology, visual fundus examination, brain imaging, EMG), laboratory testing of body fluids (lactate, aminoacids, organic acids), and analysis of bioptic samples of muscle, skin, and liver, eventually. Normal lactate level in blood does not exclude the possibility of MD. Although the aimed molecular genetic analyses may be indicated in some of mitochondrial diseases, the methods of next generation sequencing come into focus. Examples of treatment are arginine supplementation in MELAS syndrome, ketogenic diet in pyruvate oxidation disorders or quinone analogs in patients with LHON. Conclusion: The clinical suspicion of a mitochondrial disorder is often delayed, or the disease remains undiagnosed. The correct diagnosis and adequate treatment can improve prognosis of the patient. Access to genetic counseling is also of great importance.

Maskova S.,Ke Karlovu | Kolomiets A.,Ke Karlovu | Kolomiets A.,Lviv Polytechnic | Havela L.,Ke Karlovu | And 4 more authors.
Journal of Alloys and Compounds | Year: 2013

RE2T2In compounds (RE = rare earth, T is a late transition metal) were found, depending on the composition, absorbing different amounts of H. Several types of reaction of crystal structure have been found. Mere volume expansion, analogous to U2T2X compounds, was found e.g. in Tb2Pd2In, allowing to accommodate up to 2 H atoms/f.u. (one formula unit comprises 2 RE atoms). More dramatic structure modifications are required, to keep the H-H spacing higher than 2.1 Å, for higher H absorption. One type of reaction is amorphization, observed in La 2Pd2In. Other type was observed in Nd2Ni 2In, undergoing an orthorhombic distortion and forming four different H sites. The volume expansion exceeds 23%. © 2013 Elsevier B.V. All rights reserved.

Maskova S.,Ke Karlovu | Havela L.,Ke Karlovu | Danis S.,Ke Karlovu | Llobet A.,Los Alamos National Laboratory | And 5 more authors.
Journal of Alloys and Compounds | Year: 2013

Nd2Ni2In orders antiferromagnetically at T N = 8 K. A possible first-order type of the phase transition can be related to the frustrated lattice of the Shastry-Sutherland type. The transition does not shift in magnetic field but turns into a ferromagnetic transition in magnetic fields exceeding 0.3 T. Powder neutron diffraction determined the magnetic structure with Nd moments oriented mutually perpendicular along the directions of the 1 1 0 type. Large change of magnetic entropy in weak magnetic fields leads to a giant magnetocaloric effect. Reversible hydrogen absorption in pressures of several bar leads to the hydride Nd2Ni 2InH≈7 achieved through the sequence of intermediate hydrides. The highest hydride has an orthorhombic distortion and volume expansion exceeding 23%. It is antiferromagnetic below TN ≈ 3 K. © 2013 Elsevier B.V. All rights reserved.

Maskova S.,Ke Karlovu | Havela L.,Ke Karlovu | Danis S.,Ke Karlovu | Kothapalli K.,New Mexico State University | And 2 more authors.
Journal of Physics: Conference Series | Year: 2011

Weak itinerant antiferromagnetism of UNiAl is rapidly suppressed by Fe doping. Magnetic order reappears as weak ferromagnetism in UNi 0.75Fe0.25Al. The onset of magnetism can be shifted by H absorption. UNi0.85Fe0.15Al hydride is an antiferromagnet with TN approx. 70 K. Hydrogenating UNi0.70Fe 0.30Al produces a ferromagnet (TC = 90 K). Here we describe the compound with 20% of Fe and its hydride. The proximity to magnetism shows up as non-Fermi liquid behavior, detected in specific heat as upturn, followed down to 0.3 K, which is gradually suppressed in magnetic fields of several tesla. The hydride was found rather unstable, releasing H at ambient conditions, which made it unsuitable for the specific heat measurement. Magnetization study detected that the hydride shows up as ferromagnet T C ≈ 98 K.

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