The article introduces the results achieved in the creation of feasible assemblies of NdFeB magnets assembled following an already published design of a practical arrangement of magnets derived from an ideal magnetization pattern, leading to the strongest possible stray field at a remote point. It presents a method of the implementation of these assembled sets and the relevant measured dependences of magnetic induction By = f(y) and By = f(x) including their comparison with already published dependences determined by a simulation. It further presents similar dependences of magnetic induction found in the case of a trial magnetic circuit with large blocks from NdFeB magnets, and these dependences are compared both with the mentioned computer-determined dependences and the dependences measured with the corresponding implemented assembly of magnets., Václav Žežulka and Pavel Straka., and Obsahuje bibliografii
Studie Marty Hulkové se zabývá rozšířením repertoáru hudební skladatelů na pražském dvoře císaře Rudolfa II. v historickém prostoru Horních Uher v době jeho vlády., Marta Hulková., Rubrika: Studie, and Slovenské resumé na s. 157, anglický abstrakt na s. 133.
Ornithologists in Finland recorded the autumn migration of the Red Admiral butterfly, Vanessa atalanta (L.). In the best year, 1998, 1240 migrants were counted from a bird tower in September. That is, half a million butterflies migrated over a 100-km front. The butterflies were flying above forests riding on cool northerly winds. Radar indicated that a large proportion migrated at high elevations outside the visible range. These records help to resolve an "evolutionary puzzle" of why migrant butterflies and moths travel to northern latitudes when their offspring have limited possibilities of returning south. Until now, the only butterfly for which a high-elevation return migration on northerly winds is known is the American Monarch Danaus plexippus (L.).
The relations between the patterns of discontinuous gas exchange cycles (DGCs) and water loss were investigated in non-chilled diapausing pupae of the white cabbage butterfly Pieris brassicae kept at room temperature (22-24°C) in Petri dishes. An electrolytic respirometer, combined with an infrared (IR) actographic device was used for the simultaneous recordings of metabolic rate, cyclic release of carbon dioxide (bursts), passive suction inspirations (PSIs) and body movements. The patterns of cyclic gas exchange in four- and five-month-old non-chilled diapausing pupae varied individually to a considerable extent. About 40% of the pupae displayed long DGCs lasting 1-3 h, while the interburst periods were characterised by rare and almost regular large PSIs succeeding at intervals of 1-4 min. Nearly 30% of the pupae exhibited short DGCs lasting 3-5 min, while between the bursts there occurred unclear frequent gas exchange microcycles. Standard metabolic rate (SMR) did not reveal significant differences between long DGCs and short DGCs ranging from 32-56 (mean 47.6 ± 4.6) ml O2 g-1 h-1, and 28-61 (mean 44.95 ± 5.3) ml O2 g-1 h-1, respectively. The mentioned levels of SMR were characteristic of diapausing pupae.
Water loss in pupae with long DGCs was determined gravimetrically to be 0.29 ± 0.1 mg g-1 day1. At the same time, water loss in pupae that showed only short DGCs and irregular microcycles was 1.73 ± 0.31 mg g-1 day-1, which was significantly higher than in individuals characterised by long DGCs. We suggest that water loss in the non-chilled diapausing pupae may depend significantly on the patterns of cyclic gas exchange: long cycles and rare but deep PSIs exerted a marked water conserving effect.
The aim of this study was to gain more complete information about the relationships between some endogenous antioxidants and the malondialdehyde (MDA) as a marker of lipid peroxidati on, during D -galactose induced senescence. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and the concentrations of uric acid (UA) in plasma and MDA in erythrocyte’s hemolysate, were determined in 15 D -galactose (D-gal), treated rats and compared with 15 placebo. The activity of the erythrocyte’s CAT was found significantly increased due to the senescence. The ratio of the activities of antioxidant enzymes R =SOD/(GPx+CAT) was significantly decreased due to the sen escence and negatively correlated with the MDA ( ρ = -0.524, p=0.045). The antioxidant enzymes SOD and GPx negatively correlated with the MDA, while CAT displayed no correlation. Further, the UA positively correlated with the ratio of activities of the antioxidant enzymes R=SOD/(GPx+CAT), ( ρ =0.564, p=0.029 for senescent rats). Obtained results may contribute t o better understanding of the process of D-gal induced senescence in the erythrocytes., M. Mladenov, M. Gokik, N. Hadzi-Petrushev, I. Gjorgoski, N. Jankulovski., and Obsahuje bibliografii
Cíl práce: Lipoperoxidace je dávána do příčinné souvislosti s rozvojem nejdůležitějších rizikových faktorů kardiovaskulárních onemocnění. Lipoperoxidační procesy jsou důsledkem reakcí lipidů s volnými radikály bez ohledu na jejich původ. Vztah mezi triacylglyceroly (TAG) a volnými radikály (VR) není zcela jasný. Může se dokonce stát, že hypertriacylglycerolémie je doprovázena nízkými koncentracemi VR a naopak. Jedno z možných vysvětlení spočívá ve vztahu lipoperoxidace a složení mastných kyselin v molekulách TAG. Cílem této studie bylo analyzovat vztah složení mastných kyselin v TAG a produkci VR u pacientů trpících diabetes mellitus 2. typu. Typ studie: observační s kontrolní skupinou Materiál a metody: Studie zahrnovala 18 normotriacylglycerolemických (NTG) jedinců (M/F 12/6) a 24 hypertriacylglycerolemických (HTG) jedinců (M/F 16/8). Pacienti v obou skupinách byli diabetici 2. typu. Analýzu mastných kyselin v triacylglycerolech plazmy jsme provedli kapilární plynovou chromatografií a koncentrace volných radikálů byly změřeny přímou spektrofotometrií. Statistické analýzy (parametrické i neparametrické) byly provedeny pomocí statistického software STATISTICA pro Windows. Výsledky: Ve skupině HTG jsme pozorovali nižší zastoupení kyseliny myristové (14:0) (1.62 [1.23-2.07] vs. 1.90 [1.72-2.79], p = 0.022, [medián (1.-3. kvartil]) a vyšší poměr alfa-linolenové kyseliny (18:3n-3) (1.51 [1.21-1.86] vs 1.16 [1.02-1.42], p = 0.021). Poměr kyselin arachidonové/eikosapentaenové byl ve skupině HTG nižší (5.54 [3.62-7.98] vs 7.25 [5.98-15.12], p = 0.027). Když jsme HTG skupinu dále rozdělili podle koncentrací VR na tercily, prokázali jsme nižší hodnoty poměru kyseliny arachidonová/eikosapentaenová ve druhém tercilu (4.05 [2.66-4.67] vs 7.64 [5.83-11.00], 1. tercil, a 6.21 [3.20-8.31], 3. tercil p = 0.019). V spojených HTG+NTG skupinách jsme zaznamenali negativní korelaci mezi MA a TAG (r = -0.3153, p = 0.045). V triaclylglycerolech jsme prokázali pozitivní korelace VR a kyseliny stearové (p < 0.001) spolu s negativní korelací některých n-6 vícenenasycených mastných kyselin (18:3n-6, p < 0.05, 22:5n-6, p < 0.01). Závěr: Zastoupení mastných kyselin v molekulách TAG je spojeno s tvorbou VR. Nicméně do tohoto vztahu vstupují i jiné faktory., Objective: The lipoperoxidation plays a causal role in the development of most important risk factors of cardiovascular disease. The lipoperoxidation results from the reaction of lipid molecules with free radicals, regardless of their origin. The relationship between triacylglycerols (TAG) and the free radicals (FR) amount is not clear. Thus, it can turn up that the hypertriacylglyceridaemia is accompanied with the low values of FR, or vice versa. One possible explanation of this phenomenon is that the degree of lipoperoxidation of TAG is dependent on the composition of fatty acids (FA) in their molecule. Therefore, the aim of this study was to analyze FA composition in TAG and its relationship to FR production in type 2 diabetes mellitus. Design: observational study with internal control group Material and Methods: 18 normotriacylglycerolemic (NTG) individuals (12M/6F) and 24 hypertriacylglycerolemic (HTG) patients (16M/8F). Patients in both groups were persons, suffering from type 2 diabetes mellitus. Fatty acid analysis of plasma triacylglycerols was performed by gas chromatography and free radicals were determined by direct spectrophotometric method. Statistical analyses (both parametric and non-parametric) were performed with the statistical software STATISTICA for Windows. Results: We found lower content of myristic acid (14:0) (1.62 [1.23-2.07] vs. 1.90 [1.72-2.79], p = 0.022, [median (1st-3rd quartile)]) and higher content of alpha-linolenic acid (18:3n-3) (1.51 [1.21-1.86] vs. 1.16 [1.02-1.42], p = 0.021) in HTG group. The ratio of arachidonic/eicosapentaenoic acid was in HTG group lower (5.54 [3.62-7.98] vs. 7.25 [5.98-15.12], p = 0.027). When the HTG group was stratified into the tertiles by the FR concentrations, we observed lower values in the second tertile for ratios based on arachidonic acid (20:4n-6) and eicosapentaenoic acid (20:5n-3) (4.05 [2.66-4.67] vs. 7.64 [5.83-11.00], 1st tertile, and 6.21 [3.20-8.31], 3rd tertile, p = 0.019). In pooled groups, we proved negative correlation between MA and TAG (r = -0.3153, p = 0.045) and the link between FR and FA composition of TAG expressed as positive relationship of FR with content of stearic acid (p < 0.001) and negative correlation with some n-6 polyunsaturated fatty acids (18:3n-6, p < 0.05, 22:5n-6, p < 0.01). Conclusion: The composition of FA in TAG molecules has undoubtedly some relationship to the FR generation. However, the other factors seem to play a role, since the relationship is not straightforward within entire FR range., and Vecka M., Tvrzická E., Votruba M.
a1_In a series of studies in the late 1950s and early 1960s, Jan Bures introduced cortical spreading depression to the field of behavioral neuroscience (eg. Bures 1960). This technique offered a unique way to study the role of cortex in learning and memory, and attracted the attention of many who began their graduate studies at that time, including one of us (LN, cf. Nadel 1966). An NIH postdoctoral fellowship to study with the master himself brought LN to Prague in September 1967. Thus began a relationship that included science, politics, and personal life, and has lasted over 30 years1,2. The first scientific exchange began with Jan pulling a piece of paper from his desk with a long list of possible experiments written on it -- “pick one”, he said. This led to a series of studies on interhemispheric transfer of learning under conditions of monocular input, demonstrating, amongst other things, that such transfer is not a uniform process. Depending on the kind of trials given with both hemispheres intact, and the eye which remained open to input, transfer can either be non-specific, likely involving some kind of procedural knowledge, or highly specific, likely involving knowledge about the trained discrimination itself (Nadel and Buresova, 1970). These studies anticipated LN’s future work on multiple memory systems, a research enterprise pursued in the following decades by many labs (including LN’s: e.g. Nadel and O’Keefe 1974, O’Keefe et al. 1975). In this paper we focus on several scientific issues that Jan has been thinking about for the past 25 years. In particular, we consider spatial learning, the hippocampus, and memory. To this mix we add stress, something well known to anyone living in Prague in 1968., a2_LN left Prague after the 1968 invasion and stayed in London for seven months, during which time arrangements were made for an eventual return to the Medical Research Council Cerebral Functions Research Group in 1970. Thus it was that LN happened to be down the hall when John O’Keefe and Jonathan Dostrovsky discovered place cells (O’Keefe and Dostrovsky 1971) and began the program of research leading to the cognitive map theory of hippocampal function (O’Keefe and Nadel 1978)., L. Nadel, J.D. Payne., and Obsahuje bibliografii
The aim of this study was to determine the effects of insulin infusion on oxidative stress induced by acute changes in glycemia in non-stressed hereditary hypertriglyceridemic rats (hHTG) and Wistar (control) rats. Rats were treated with glucose and either insulin or normal saline infusion for 3 hours followed by 90 min of hyperglycemic (12 mmol/l) and 90 min of euglycemic (6 mmol/l) clamp. Levels of total glutathione (GSH), oxidized glutathione (GSSG) and total antioxidant capacity (AOC) were determined to assess oxidative stress. In steady states of each clamp, glucose infusion rate (GIR) was calculated for evaluation of insulin sensitivity. GIR (mg.kg-1.min-1) was significantly lower in hHTG in comparison with Wistar rats; 25.46 (23.41 - 28.45) vs. 36.30 (27.49 - 50.42) on glycemia 6 mmol/l and 57.18 (50.78 - 60.63) vs. 68.00 (63.61 - 85.92) on glycemia 12 mmol/l. GSH/GSSG ratios were significantly higher in hHTG rats at basal conditions. Further results showed that, unlike in Wistar rats, insulin infusion significantly increases GSH/GSSG ratios in hHTG rats: 10.02 (9.90 - 11.42) vs. 6.01 (5.83 - 6.43) on glycemia 6 mmol/l and 7.42 (7.15 - 7.89) vs. 6.16 (5.74 - 7.05) on glycemia 12 mmol/l. Insulin infusion thus positively influences GSH/GSSG ratio and that way reduces intracellular oxidative stress in insulin-resistant animals., M. Žourek, P. Kyselová, J. Mudra, M. Krčma, Z. Jankovec, S. Lacigová, J. Víšek, Z. Rušavý., and Obsahuje bibliografii a bibliografické odkazy
Modal composition and grain-size characteri stics, physical and mechanical propertie s of three samples of Archean gneisses of the Kola series from the depths of 6.8 to 8.4 km of the Kola Superdeep Borehole (KSDB-3) and two collections of their surface analogues were analysed. On the basis of a comparison of the petrographic characteristics of the borehole samples and analogues, it was found that not all analogues are equivalents of corresponding core samples completely. Mechanical properties of core samples are affected by depth of the core sample position in the borehole. This work forms part of the research in the frame of the INTAS Project No.314 "Geodynamics in the cross-section of the Kola superdeep"., Jiřina Trčková, Vladimír Šrein, Martin Šťastný and Roman Živor., and Obsahuje bibliografické odkazy