Paola Bertoli, Veronica Grembi., Obsahuje bibliografii a bibliografické odkazy., České resumé, and Vydává: Univerzita Karlova, Centrum pro ekonomický výzkum a doktorské studium, Národohospodářský ústav AV ČR
Two different pathways for protochlorophyllide a (Pchlide) reduction in photosynthetic organisms have been proved: one is strictly light-dependent whereas the second is light-independent. Both pathways occur in all photosynthetic cells except in angiosperms which form chlorophyll only through the light-dependent pathway. Most cells belonging to Eubacteria (i.e., the anoxygenic photosynthetic bacteria) synthesize bacteriochlorophyll through the light-independent pathway. This review deals with the physiological, biochemical, and molecular biological features of molecules involved in both pathways of Pchlide reduction.
In slurry transport of settling slurries in Newtonian fluids, it is often stated that one should apply a line speed above a critical velocity, because blow this critical velocity there is the danger of plugging the line. There are many definitions and names for this critical velocity. It is referred to as the velocity where a bed starts sliding or the velocity above which there is no stationary bed or sliding bed. Others use the velocity where the hydraulic gradient is at a minimum, because of the minimum energy consumption. Most models from literature are one term one equation models, based on the idea that the critical velocity can be explained that way. Here the following definition is used: The critical velocity is the line speed below which there may be either a stationary bed or a sliding bed, depending on the particle diameter and the pipe diameter, but above which no bed (stationary or sliding) exists, the Limit Deposit Velocity (LDV). The way of determining the LDV depends on the particle size, where 5 regions are distinguished. These regions for sand and gravel are roughly; very small particles up to 0.014-0.040 mm (d < δv), small particles from δv-0.2 mm, medium particles in a transition region from 0.2-2.00 mm, large particles > 2 mm and very large particles > 0.015·Dp. The lower limit of the LDV is the transition between a sliding bed and heterogeneous transport. The new model is partly based on physics and correlates well with experiments from literature.
Expanding the domain of majority rule is widely seen as desirable for the European Union. But the functioning of majority rule depends on preconditions that are seldom taken into account. The basic precondition is that overruled minorities accept majority decisions instead of exiting the voting unit. The specific problem of applying majority rule in the European Union is that overruled minorities at the European level are majorities at the nation-state level. By distinguishing between three dimensions of conflicts - content, time and space - the article analyses under what conditions it is possible to expect minorities to accept majority decisions, thus enabling the resolution of conflict by majority rule at the European level.
Utilization of a magnetic force can be found in many mechatronic applications, where e.g. a slender beam or plate is subjected to static magnetic force generated by an electromagnetic actuator consisting of a solenoid wound on a ferromagnetic core and a ferromagnetic armature, fixed to the beam. The static magnetic force, acting perpendicularly onto the beam, causes sag (downwards bending) of the beam. If the magnitude of the magnetic force surpasses some threshold value the armature and hence the beam is completely attracted to the core of the solenoid. For small detections the mathematical expression of the magnetic force can be linearised and approximated by a polynomial dependence on the distance to the electromagnet. In practical application, it is important to analyse the nature of the sag and to determine the limits of the linear approxmation, as well as the limits leading to the full attraction to the electromagnet. The mathematical generalisation of the sag is valid for electrostatic force between planar electrodes, too. and Obsahuje seznam literatury
The effect of normobaric oxygen atmosphere on hypoxia-enhanced lipid peroxidation in the brain cortex, subcortical structures, medulla oblongata and in the cerebellum was observed in 7- and 21-day-old and adult rats. The production of free oxygen radicals causing lipid peroxidation was assessed by the method described by Ohkawa et al. (1979). The rats were exposed for 30 min to 100 % oxygen atmosphere which significantly stimulated the production of malondialdehyde (MDA) in all the studied regions of the brain in 7- and 21-day-old male rats, and in the brain cortex and subcortical structures of adult males. Higher levels of MDA were found in the brain cortex of 7-day-old female rats only. Reoxygenation with pure oxygen after 30 min hypobaric hypoxia corresponding to 9000 m increased MDA production in all studied parts of the brain on both male and female rats 7- and 21-day-old. In adult rats significantly increased MDA production was only found in the brain cortex of male and female rats and in the subcortical structures of males. The exposition to hypobaric hypoxia followed by reoxygenation by atmospheric air enhanced MDA production in all studied regions of the brain in 7-day-old males and in the cerebellum of females; in 21-day-old rats of both sexes a significant increase of MDA was detected in all parts of the brain. In adult rats were found higher MDA levels in the cerebral cortex of both males and females.
Photodynamic therapy (PDT) is now being used more frequently in carefully selected cases of malignancies. The drugs used for PDT are mostly derivatives of haematoporphyrine (HPD) and its active component photofrine II. Another compound prepared by total synthesis is meso-tetra-(4-sulfonatophenyl)-porphine (TPPS4) but its application in human medicine was rejected because of its neurotoxicity. Our TPPS4 was prepared by the method of Busby et al. in the modification of Jirsa and Kakaë (1987). This product is purer and without neurotoxic effects. In this study, we concentrated our attention on the effect of TPPS4 on nephrotoxicity and its accumulation in some organs. As the parameters of toxic kidney damage we used urine levels of N-acetyl-beta-D-glucosaminidase (NAG), serum creatinine levels, glomerular filtration rate (GFR) and proteinuria. TPPS4 was administered i.v. in a dose of 25 mg/kg b.w. The animals were observed for 21 days after drug application. Urine and blood samples were collected over 24-hour periods on days 0, 5 and 21. The serum creatinine level was significantly higher only on day 5 (65.0±1.46 /zmol/1 vs 56.5±2.69 ^mol/1 on day 0, p<0.05). There were no significant changes in GFR, proteinuria or NAG activity in the urine during the experiment. AST serum activity was increased. We determined the concentration of TPPS4 (pmol/mg w.w.) in rat organs on the 21st day after the injection. The concentration of TPPS4 was high in kidneys (30.8 ±5.5), liver (13.5 ±2.0), lungs (11.7 ±4.6) and spleen (9.7 ±1.5), while the concentration in heart and brain was low. We conclude that TPPS4 has the highest concentration in the kidney 21 days after its administration and does not exert any nephrotoxic effects during this period.
There are only few studies concerning about long-term effect of growth hormone (GH) replacement therapy on bone mineral density and bone microstructure. To assess effect of GH replacement therapy on bone mineral density (BMD) and trabecular bone score (TBS) in adult GH deficient (AGHD) subjects over period of 10 years. From 2005 to 2018, a prospective study of AGHD patients was conducted in national referral center for treatment of GHD. All patients received subcutaneous recombinant human GH in an IGF-1-normalizing regimen once a day. Lumbar spine (L-spine) and total hip (TH) BMD using Hologic densitometers were measured at baseline and every two years during treatment with rhGH. TBS was derived from L1-L4 DXA using iNsight® software (Medimaps, France) at each time point. Periods of measurement were baseline, year 2; 4; 6; 8 and 10. In total, 63 patients (38 males, 25 females, mean age 25.1±16 years) were included in the study. After 10 years of GH treatment, IGF-1 significantly increased (~35 %), with greatest increase at year 2. During 10-year follow-up, L-spine BMD increased approximately of 7 % (NS). TH BMD increase of 11 % during follow-up (p=0.0003). The greatest increment of BMD was achieved at year 6 on both sites, L-spine (+6 %) and TH BMD (+13 %) (p<0.05). There was no significant change of TBS during whole follow-up. In this study, sustaining positive effect of GH replacement therapy on bone density in subjects with adult GH deficiency over 10 years of follow-up was observed. The study did not show effect on TBS, as indirect measure of trabecular bone microarchitecture., Peter Vaňuga, Martin Kužma, Dáša Stojkovičová, Juraj Smaha, Peter Jackuliak, Zdenko Killinger, Juraj Payer., and Obsahuje bibliografii
The effect of oestradiol administration and restricted feeding on longitudinal tibia growth was investigated in immature male rats. The restrictedly fed animals had a significantly longer tibia, greater thickness of the growth plate, faster rate of longitudinal tibial growth as well as the greater rate of [methyl-3H]thymidine incorporation into the growth plate of the tibia compared with oestradiol-treated animals. The results indicate that, in immature male rats, exogenous oestradiol can decrease the longitudinal growth of the tibia (at least partly due to inhibition of cell proliferation in the growth plate) independently of its anorexic effect.
Chlorophyll a (Chl a) has an asymmetrical molecular organization, which dictates its orientation and the location of the pigment in the mature photosynthetic apparatus. Although Chl a fluorescence (ChlF) is widely accepted as a proxy for plant photosynthetic performance under countless stress conditions and across species, a mechanistic understanding of this causality is missing. Since water plays a much greater role than solvent for the photosynthetic machinery, elucidating its influence on Chl a may explain the reliable reflection of plant stress response in the ChlF signal. We examine the effect of hydration from well-watered to lethal drought on ChlF imagery results across morphologically diverse species to begin testing the impact of molecular scale hydration of Chl a on ChlF. Our results support a conceptual model where water is an integral part of the photosystems' structure and directly influences Chl a behavior leading to changes in the energy partitioning and ultimately in ChlF., C. R. Guadagno, D. P. Beverly, B. E. Ewers., and Obsahuje bibliografické odkazy