Influence of L-carnitine supplementation on diurnal blood pressure rhythm in obese type 2 diabetic subjects with autonomic neuropathy

Wstęp Neuropatia cukrzycowa może wpływać na dobowy rytm ciśnienia tętniczego. Istnieją przypuszczenia, że w rozwoju neuropatii cukrzycowej oraz insulinooporności może brać udział zaburzona przemiana karnityny. Celem podjętych badań była ocena stężeń karnityny całkowitej i wolnej w surowicy oraz dobowego rytmu ciśnienia tętniczego u otyłych chorych na cukrzycę typu 2 z neuropatią autonomiczną i bez neuropatii, jak również ocena wpływu stosowania L-karnityny na funkcję układu autonomicznego i dobowy rytm ciśnienia u tych chorych. Materiał i metody Badaniami objęto 30 otyłych osób chorych na cukrzycę typu 2, leczonych lekami doustnymi. U 15 chorych stwierdzono subkliniczną neuropatię autonomiczną układu sercowo-naczyniowego (grupa NA(+)), natomiast u 15 osób nie stwierdzono obecności tego powikłania (grupa NA(-)). Grupę kontrolną stanowiło 15 otyłych osób bez cukrzycy. U wszystkich badanych wykonano pomiar wskaźnika masy ciała (BMI), wskaźnika talia/biodra (WHR), oznaczano stężenie karnityny wolnej i całkowitej, glukozy, insuliny, peptydu C, HbA1c i lipidów. Neuropatię autonomiczną układu sercowo-naczyniowego oceniano na podstawie baterii testów według Ewinga. Ambulatoryjny, 24-godzinny pomiar ciśnienia tętniczego wykonano za pomocą urządzenia SpaceLabs 90207. Badania przeprowadzono w warunkach wyjściowych oraz po 3 miesiącach stosowania L-karnityny podawanej doustnie w dawce 1000 mg/d. Wyniki We wszystkich badanych grupach wiek, płeć, wskaźnik BMI i WHR były zbliżone. Podobny był także dobowy rytm ciśnienia tętniczego i liczba osób wykazujących prawidłowy spadek ciśnienia w nocy. Grupy NA(+) i NA(–) nie różniły się pod względem stężenia karnityny wolnej i całkowitej, wyrównania cukrzycy, stężenia insuliny i peptydu C, a także stężeń cholesterolu i jego frakcji oraz triglicerydów. Mimo iż stosowanie karnityny u chorych na cukrzycę prowadziło do istotnego wzrostu jej stężenia w surowicy, nie miało wpływu na masę ciała, funkcję układu autonomicznego i dobowy rytm ciśnienia. Wnioski Obecność subklinicznej neuropatii autonomicznej u otyłych chorych na cukrzycę typu 2 nie wpływa na dobowy rytm ciśnienia i nie wykazuje związku ze stężeniami karnityny wolnej i całkowitej. Stosowanie karnityny nie wpływa na neuropatię autonomiczną ani na dobowy rytm ciśnienia tętniczego.Background Diabetic autonomic neuropathy can be associated with abnormalities in diurnal blood pressure rhythm. It has been suggested that carnitine deficiency can be involved in the development of both diabetic neuropathy and insulin resistance. The aim of the study was to assess serum carnitine levels and diurnal blood pressure rhythm in obese type 2 diabetic subjects with subclinical autonomic neuropathy and without neuropathy and to determine influence of L-carnitine supplementation on autonomic neuropathy and blood pressure rhythm. Material and methods Study was performed in 30 obese type 2 diabetic patients treated with oral antidiabetic agents. Subclinical autonomic neuropathy of cardiovascular system was present in 15 of them - group NA(+) and was not found in 15 others - group NA(-). Control group consisted of 15 obese, nondiabetic subjects. In all subjects body mass index (BMI), waist-hip ratio (WHR), fasting serum free and total carnitine, glucose, insulin, C-peptide, lipids and HbA1c were measured. Assessment of autonomic neuropathy was based on a Ewing’s battery of autonomic function tests. Ambulatory blood pressure monitoring was performed with SpaceLabs 90207. Investigation was performed twice, before and after supplementation of 1000 mg L-carnitine per day, given orally for 3 month. Results No differences in age, sex, BMI and WHR was found in all investigated groups. Diurnal blood pressure rhythm and number of subjects with normal night blood pressure fall was similar in NA(-) and NA(+) patients. Similar levels of free and total carnitine, glucose, insulin, C-peptide, HbA1c, total cholesterol, LDL, HDL cholesterol and triglicerides were found in NA(+) and NA(-) groups. After supplementation of L-carnitine in diabetic patients, serum carnitine levels increased but there was no change in BMI, autonomic nervous system function and blood pressure rhythm. Conclusions Subclinical autonomic neuropathy in obese type 2 diabetic subjects is not associated with serum carnitine concentration and abnormalities in blood pressure rhythm. Supplementation of L-carnitine does not influence the autonomic neuropathy and diurnal blood pressure rhythm

High Frequency Induction Tube Furnace for Determination of Ash Melting Temperature

The article describes the designed and manufactured tube furnace intended for, inter alia, determining the melting temperature of ash conforming to the standard of ISO-540:2001. The possibility of digital sample observation and several programs controlling the obtainable temperature enable to determine the test cycle in any case (convenient for the researcher). Reduction of testing time allows for the analysis of the observed phenomena, as well as more detailed research plan of samples, where substantial changes have been demonstrated

The cAMP Inducers Modify N-Acetylaspartate Metabolism in Wistar Rat Brain

Neuronal N-acetylaspartate production appears in the presence of aspartate N-acetyltransferase (NAT8L) and binds acetyl groups from acetyl-CoA with aspartic acid. Further N-acetylaspartate pathways are still being elucidated, although they seem to involve neuron-glia crosstalk. Together with N-acetylaspartate, NAT8L takes part in oligoglia and astroglia cell maturation, myelin production, and dopamine-dependent brain signaling. Therefore, understanding N-acetylaspartate metabolism is an emergent task in neurobiology. This project used in in vitro and in vivo approaches in order to establish the impact of maturation factors and glial cells on N-acetylaspartate metabolism. Embryonic rat neural stem cells and primary neurons were maturated with either nerve growth factor, trans-retinoic acid or activators of cAMP-dependent protein kinase A (dibutyryl-cAMP, forskolin, theophylline). For in vivo, adult male Wistar rats were injected with theophylline (20 mg/kg b.w.) daily for two or eight weeks. Our studies showed that the N-acetylaspartate metabolism differs between primary neurons and neural stem cell cultures. The presence of glia cells protected N-acetylaspartate metabolism from dramatic changes within the maturation processes, which was impossible in the case of pure primary neuron cultures. In the case of differentiation processes, our data points to dibutyryl-cAMP as the most prominent regulator of N-acetylaspartate metabolism

Neither Excessive Nitric Oxide Accumulation nor Acute Hyperglycemia Affects the N-Acetylaspartate Network in Wistar Rat Brain Cells

The N-acetylaspartate network begins in neurons with N-acetylaspartate production catalyzed by aspartate N-acetyltransferase from acetyl-CoA and aspartate. Clinical studies reported a significant depletion in N-acetylaspartate brain level in type 1 diabetic patients. The main goal of this study was to establish the impact of either hyperglycemia or oxidative stress on the N-acetylaspartate network. For the in vitro part of the study, embryonic rat primary neurons were treated by using a nitric oxide generator for 24 h followed by 6 days of post-treatment culture, while the neural stem cells were cultured in media with 25–75 mM glucose. For the in vivo part, male adult Wistar rats were injected with streptozotocin (65 mg/kg body weight, ip) to induce hyperglycemia (diabetes model) and euthanized 2 or 8 weeks later. Finally, the biochemical profile, NAT8L protein/Nat8l mRNA levels and enzymatic activity were analyzed. Ongoing oxidative stress processes significantly affected energy metabolism and cholinergic neurotransmission. However, the applied factors did not affect the N-acetylaspartate network. This study shows that reduced N-acetylaspartate level in type 1 diabetes is not related to oxidative stress and that does not trigger N-acetylaspartate network fragility. To reveal why N-acetylaspartate is reduced in this pathology, other processes should be considered

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Competition of Magnetocrystalline Anisotropy of Uranium Layers and Zig-Zag Chains in UNi0.34_{0.34}Ge2_2 Single Crystals

Structural and thermodynamic properties of single-crystalline UNi$_{1-x}$Ge$_2$ with $x$\,=\,0.66 have been investigated by measuring magnetization, specific heat, and thermal expansion over a wide range of temperatures and magnetic fields. The measurements revealed the emergence of a long-range antiferromagnetic ordering of uranium magnetic moments below the N{\'e}el temperature $T_{\rm N}$\,=\,45.5\,K and the existence of two easy axes in the studied compound, namely $b$ and $c$, which correspond to the planes of the uranium zig-zag chains. Magnetic field applied along these two crystallographic directions induces in the system a first-order metamagnetic phase transition (from antiferromagnetism to field-polarized paramagnetism), and the width of the magnetic hysteresis associated with that transition reaches as much as 40 kOe at the lowest temperatures. A magnetic phase diagram developed from the experimental data showed that the metastable region associated with that magnetic hysteresis forms a funnel that narrows toward the N{\'e}el point in zero magnetic field. The four-layer Ising model has successfully predicted the collinear antiferromagnetic structure in UNi$_{0.34}$Ge$_2$ (known from earlier reports), its magnetic phase diagram, and temperature and field variations of its magnetization. Moreover, it suggests that the first-order phase transition extends down to zero magnetic field, although it is barely detectable in the experiments performed in low magnetic fields. According to this model, the second-order phase transition occurs in the compound only in zero field.Comment: 15 pages, 12 figure

Competition of magnetocrystalline anisotropy of uranium layers and zigzag chains in UNi0.34Ge2 single crystals

International audienceStructural and thermodynamic properties of single-crystalline UNi1-xGe2 with x = 0.66 have been investigated by measuring magnetization, specific heat, and thermal expansion over a wide range of temperatures and magnetic fields. The measurements revealed the emergence of a long-range antiferromagnetic ordering of uranium magnetic moments below the Neel temperature T-N = 45.5(1) K and the existence of two easy axes in the studied compound, namely, b and c, which correspond to the plane of the uranium zigzag chains. Magnetic field applied along these two crystallographic directions induces in the system a first-order metamagnetic phase transition (from antiferromagnetism to field-polarized paramagnetism), and the width of the magnetic hysteresis associated with that transition reaches as much as about 40 kOe at the lowest temperatures. A magnetic phase diagram developed from the experimental data showed that the metastable region associated with that magnetic hysteresis forms a funnel that narrows toward the Neel point in a zero magnetic field. The four-layer Ising model has successfully predicted the collinear antiferromagnetic structure in UNi0.34Ge2 (known from earlier reports), its magnetic phase diagram, and temperature and field variations of its magnetization. Moreover, it suggests that the first-order phase transition extends down to a zero magnetic field, although it is barely detectable in the experiments performed in low magnetic fields. According to this model, the second-order phase transition occurs in the compound only in a zero field