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In arid soils, humic acids (HAs) are used as amendments to improve water uptake from the atmosphere. This method of harvesting water involves several steps depending on the relative humidity (RH). At low RH, water is adsorbed solely on primary sorption sites such as polar groups. As RH increases, more water is adsorbed on polar groups forming secondary sorption sites, which grow as the RH increases. As a result, the neighboring sorption sites can connect to form water molecule bridges (WaMBs). The WaMBs are responsible for the transport of water in the form of clusters into hydrophobic pores resulting in an increase in water content in organic matter (OM), swelling of OM and formation of phase water. HA being a complex mixture complicates the understanding of the relationship between the proportion of polar groups and properties of water. The understanding of these relationships can guide the design of humic-based amendments applicable in arid systems. To address this issue, seven HAs were characterized by nuclear magnetic resonance followed by the investigation of the properties of water (water content, strength of WaMBs and strength of water binding) on the HAs. Results showed that the content of polar groups positively correlated with the amount of water adsorbed by HA and the stability of WaMBs. It was found that presumably apolar moieties such as aromatics and phenols increased the binding energy of water to HA thereby appearing to be responsible for preventing the desiccation. In addition, between 44 and 76% RH, the WaMB stability positively correlated with O-alkyl and peptides moieties. Therefore, both polar and apolar domains influence water properties depending on RH. We conclude that this synergism is an advantage in systems composed of hydrophobic and hydrophilic molecules held together by weak interactions providing high flexibility to the system under arid conditions.

The composition of lipids in soil offers clues to soil degradation processes due their persistency and selectivity in soil, and close relation to long-term processes in the ecosystem, thanks to their role in cell membranes of organisms. Organic solvent-extractable compounds were recovered from soils collected at two sites differing in the degree of forest damage. Gas chromatography/mass spectroscopy and Fourier transform infrared spectroscopy were applied in order to characterize solvent-extractable lipids. Raman spectroscopy was also applied as it provides distinct advantages for determining the structural order of carbonaceous materials. The organic matter measurement techniques were combined with an established simultaneous multi-element measurement technique. Variations in individual soil horizons from the sites were reflected in the crystallinity of epicuticular waxes, presence of long-chain aliphatic hydrocarbons, concentrations of n-alkanes, saturated and unsaturated fatty acids, dicarboxylic acids, and in the content of aromatic structures, hydroxyl, ester, and carboxylic acid groups. The results are explained by differently transformed organic matter. The concentrations of elements in the soils were also affected by atmospheric depositions, including higher accumulations of arsenic and antimony, and lower contents of natural nutrients. These data have potential to be used as sensitive biogenic indicators of ecosystem damage by long-term atmospheric depositions.

Recentni výzkum výživy v akutni fazi onemocněni ukazal důležite nove poznatky o podavani vyssich davek proteinů a možných nežadoucich ucincich u pacientů v katabolizmu. Na druhou stranu se ukazuje, že realimentacni hypofosfatemie a realimentacni syndrom může být významným problemem u chronicky podvyživených akutně hospitalizovaných pacientů. Navic se zda, že enteralni výživa nemusi být výhodnějsi než parenteralni výživa u pacientů v sokovem stavu, u kterých dokonce nelze vyloucit horsi výsledky enteralni přistupu. Nově je k dispozici navrh globalniho konsenzualniho postupu pro diagnostiku malnutrice v klinicke praxi u dospělých. Konecně byla nedavno zveřejněna doporuceni European Society of Clinical nutrition and Metabolism (ESPEN) pro výživu v intenzivni peci a nutricni podporu u chronicky polymorbidnich pacientů na internich oddělenich. Přehledný clanek uvadi nove poznatky a doporuceni a snad ovlivni klinickou praxi nutricni podpory pacientů v akutnich stavech a nasledne rekonvalescenci.

Physical and chemical structure affect properties of dissolved organic matter (DOM). Recent observations revealed that heating and cooling cycles at higher temperature amplitude lead to a change in DOM physical conformation assumingly followed by a slow structural relaxation. In this study, changes at lower temperature amplitudes and their relation to DOM composition were investigated using simultaneous measurements of density and ultrasonic velocity in order to evaluate the adiabatic compressibility, which is sensitive indicator of DOM structural microelasticity. Six fulvic acids (FAs) having various origins were analyzed at concentrations of 0.12, 0.6 and 1.2 g L−1 and at different temperature amplitudes. First, we validated that the used technique is sensitive to distinguish conclusively the structural changes upon heating and cooling of DOM with heating/cooling amplitude of ± 3 °C and higher. This amplitude was then applied to observe the relationship between change in adiabatic compressibility and chemical composition of FA. No correlation was observed with elemental composition and aromatic structures. Positive correlations were observed with content of alkyl moieties, carboxylic and carbonyl carbons and biological activity. Based on literature data, it was concluded that alkyl moieties undergo (re)crystalization during thermal fluctuation and their structural relaxation back is very slow (if occurs). The polar moieties form a flexible hydrogel responding to thermal fluctuation by moderate dissolution and re-aggregation. Negative correlation was observed in relation to the amount of peptide and O-alkyl systems, which can be attributed to very fast structural relaxation of proteinaceous materials, i.e. their larger content leads to lower difference between original and heat-induced compressibility. Last, the increase of the heating/cooling amplitude from ± 3 to ± 15 °C resulted in an increase of the change of the adiabatic compressibility and in the extension of the relaxation time needed for DOM structure to return to the equilibrium. We conclude that this increase is caused by the increase in inner energy, and DOM conformation can reach a cascade of energy minima, which may influence DOM reactivity and biodegradability.

Omega-3 polyunsaturated fatty acids (&omega, 3PUFAs) are introduced into parenteral nutrition (PN) as hepatoprotective but may be susceptible to the lipid peroxidation while olive oil (OO) is declared more peroxidation resistant. We aimed to estimate how the lipid composition of PN mixture affects plasma and erythrocyte lipidome and the propensity of oxidative stress. A cross-sectional comparative study was performed in a cohort of adult patients who were long-term parenterally administered &omega, 3 PUFAs without (FO/&ndash, n = 9) or with (FO/OO, n = 13) olive oil and healthy age- and sex-matched controls, (n = 30). Lipoperoxidation assessed as plasma and erythrocyte malondialdehyde content was increased in both FO/&ndash, and FO/OO groups but protein oxidative stress (protein carbonyls in plasma) and low redox status (GSH/GSSG in erythrocytes) was detected only in the FO/&ndash, subcohort. The lipidome of all subjects receiving &omega, 3 PUFAs was enriched with lipid species containing &omega, 3 PUFAs (FO/&ndash, ˃FO/OO). Common characteristic of all PN-dependent patients was high content of fatty acyl-esters of hydroxy-fatty acids (FAHFAs) in plasma while acylcarnitines and ceramides were enriched in erythrocytes. Plasma and erythrocyte concentrations of plasmanyls and plasmalogens (endogenous antioxidants) were decreased in both patient groups with a significantly more pronounced effect in FO/&ndash, We confirmed the protective effect of OO in PN mixtures containing &omega, 3 PUFAs.

Monografie Elektronizace výuky práva shrnuje dosavadní poznatky s využíváním digitálních technologii na Fakultě právnické Západočeské univerzity v Plzni, Právnické fakultě Univerzity Karlovy a Ústavu státu a práva AV ČR. Ačkoliv všichni autoři podporují digitalizací výuky, jejich názory na její provedení se různí, což považujeme za pozitivní. Podobně je tomu i u studentů, jak ukazují výsledky průzkumu prováděného kolegy z pražské právnické fakulty. Digitalizace je sice nezvratný a v zásadě pozitivní proces, který ovšem současně přináší do výuky tak zásadní změny, že zatím se s nimi obtížně vyrovnávají jak studenti, tak učitelé. Autoři upozorňují i na negativní trendy, které zejména s povrchní digitalizací souvisí. Společné mínění autorů vychází z teze, že digitalizovat má smysl tam, kde digitalizace skutečně zvýší kvalitu výuky práva.

Long-chain n-3 polyunsaturated fatty acids modulate immune cell functions. The primary objective of this study was to evaluate the impact of different lipid emulsions (LEs) with supplemented doses of fish oil (FO) on serum cytokine concentration and in vitro cytokine production in patients with intestinal failure on home parenteral nutrition (HPNPs). We hypothesized that FO supplementation would diminish lipopolysaccharide (LPS)-stimulated cytokine production. Twelve HPNPs receiving Smoflipid for at least 3 months were given FO (Omegaven) for a further 4 weeks. After this cycle, the patients were randomized to subsequently receive 1 cycle with Lipoplus and 1 cycle with ClinOleic for 6 weeks or vice versa plus 4 weeks of added Omegaven after each cycle in a crossover design. Comparison of the baseline LE regimens showed lower LPS-stimulated production of IL-1β in the HPNPs on Lipoplus than on the Smoflipid and ClinOleic regimens, as well as lower IL-8 compared to the Smoflipid regimen. Omegaven reduced IL-8 concentration in serum under the Lipoplus regimen and diminished LPS-stimulated production of IL-1β under the Smoflipid and ClinOleic. IL-6 and TNF-α production was depressed only in those on Smoflipid. Irrespective of the LE used, the HPNPs compared to the healthy controls showed higher IL-6, IL-8, and TNF-α concentrations in serum and LPS-stimulated production of IL-6 as well as lower n-6/n-3 long-chain polyunsaturated fatty acids in the erythrocyte phospholipids. LPS-stimulated production of IL-6 correlated negatively with the parenteral dose of eicosapentaenoic acid + docosahexaenoic acid. In conclusion, FO-supplemented parenteral nutrition suppresses in vitro cytokine production.

Background: The objective of the present study was to determine concentrations of zinc (Zn), copper (Cu), iron (Fe), selenium (Se) in blood plasma and manganese (Mn) in the whole blood in patients with long-term home parenteral nutrition (HPN) in comparison to the control group. Patients and Methods: We examined 68 patients (16 men and 52 women) aged from 28 to 68 years on a long-term HPN lasting from 4 to 96 months. The short bowel syndrome was an indication for HPN. The daily doses of Zn, Cu, Fe, Se and Mn in the last 3 months were determined. Results: No significant differences in blood plasma were found for Zn, Cu and Fe in patients with HPN and in the control group (p > 0.05). The concentration of Mn in whole blood was significantly increased in HPN patients (p < 0.0001), while Se concentration in these patients was significantly decreased (p < 0.005). The concentration of Mn in the whole blood of 16 patients with cholestasis was significantly increased compared to the patients without cholestasis (p < 0.001). The Cu concentration was increased with no statistical significance. Conclusion: In long-term HPN, the status of trace elements in the patients has to be continually monitored and the daily substitution doses of these elements have to be flexibly adjusted. Dosing schedule needs to be adjusted especially in cases of cholestatic hepatopathy. A discussion about the optimal daily dose of Mn in patients on HPN is appropriate. For clinical practice, the availability of a substitution mixture of trace elements lacking Mn would be advantageous.

The interactions of fungal guilds have recently been proposed as drivers of organic matter transformation in forest soils. We conducted a pot experiment with Norway spruce seedlings planted in spruce needle litter inoculated with several fungal strains belonging to different ecological guilds (saprotrophic, mycorrhizal, and root endophytic) to assess how the fungi and their interactions affect the transformation of humic substances (HS) and phosphorus (P) in the litter. Several methods for the characterization of P forms and HS were employed, including 31P NMR, UV–Vis and FTIR spectroscopy. Our results show that fungal interactions influence not only the flow of P in decaying (plant) litter but also the transformation of the soil organic matter itself. Pots with saprotrophic Gymnopus androsaceus generally retained more P and prevented the accumulation of phosphonates caused by mycorrhizal Hyaloscypha finlandica, highlighting the strong competitive ability of the former species. The increased mineralization of P caused by G. androsaceus was not observed in the combined treatments, suggesting that other present fungi took up part of the inorganic P. The tested fungi did not affect the amount of HS produced but changed the characteristics of the HS. Mycorrhizal H. finlandica and root endophytic Phialocephala fortinii increased the relative proportion of carboxylic moieties in the HS regardless of the presence or absence of G. androsaceus, probably via the production and incorporation of melanins. The UV–Vis absorbance characteristics of the HS were significantly influenced by fungal interactions. Mycorrhizal H. finlandica and Hebeloma bryogenes retarded humification, as determined by the A4/6 ratio. We attribute the similar shift observed in Serpula himantoides to the partial oxidative degradation of HS. Our study shows that fungal root endophytes can significantly contribute to litter transformation along with mycorrhizal and saprotrophic fungi. The extent and patterns of the transformation seem to be species-dependent in all studied fungal groups.

Markers of oxidative stress and antioxidant status in relation to inflammatory mediators in septic patients (SPs) during the course of sepsis and after recovery were analysed. Patients were 30 critically ill adults in severe sepsis/septic shock, 19 of which completed 3 samplings (S1: within 24 h after onset of sepsis, S7: 7 days after S1, R7: 7 days after clinical recovery). Comparing SPs with healthy controls (HCs), enhanced C-reactive protein, procalcitonin, bilirubin and CuZn-superoxide dismutase activity were found at S1 only. Oxidized low-density lipoprotein, conjugated dienes and nitrotyrosine were increased at S1, culminated at S7 and reverted nearly to HC levels at R7. Reduced catalase activity and serum amyloid were observed at S1 and endured until R7. Increase in IL-6, IL-10 and tumour necrosis factor alpha (TNF-α) with accompanying decrease in apolipoprotein A1, high-density lipoprotein (HDL) cholesterol, selenium, zinc, albumin, paraoxonase 1 and glutathione peroxidase 1 activity appeared at S1 and persisted until R7. TNF-α, IL-10 and markers of oxidative stress were in negative correlation with HDL cholesterol and albumin at R7. After clinical recovery, increased cytokines and decreased antioxidants were accompanied by lower albumin and HDL cholesterol levels. During this important and beneficial period of tissue repair, patients with prolonged persistence of this status are probably more vulnerable to secondary infections and should be dealt with as constituting a high-risk population.

The composition and structure of humic acids isolated from lignohumate, which is produced by hydrolytic–oxidative conversion of technical lignosulfonates, were characterized by chemical and spectral methods (UV/VIS, FTIR, and 13 C NMR spectroscopy). As comparative samples, humic acids (HA) were isolated also from lignite and organic horizon of mountain spruce forest soil. When compared with other HA studied, the lignohumate humic acids (LHHA) contained relatively few carboxyl groups, whose role is partly fulfilled by sulfonic acid groups. Distinctive 13 C NMR signal of methoxyl group carbons, typical for lignin and related humic substances, was found at the shift of 55.9 ppm. Other alkoxy carbons were present in limited quantity, like the aliphatic carbons. Due to the low content of these carbon types, the LHHA has high aromaticity of 60.6%. Comparison with the natural HA has shown that lignohumate obtained by thermal processing of technical lignosulfonate can be regarded as an industrially produced analog of natural humic substances. Based on the chemical and spectral data evaluation, structural features of lignohumate humic acids were clarified and their hypothetical chemical structure proposed, which described typical “average” properties of the isolated fraction.

Continuous normobaric hypoxia (CNH) renders the heart more tolerant to acute ischemia/reperfusion injury. Protein kinase C (PKC) is an important component of the protective signaling pathway, but the contribution of individual PKC isoforms under different hypoxic conditions is poorly understood. The aim of this study was to analyze the expression of PKCepsilon after the adaptation to CNH and to clarify its role in increased cardiac ischemic tolerance with the use of PKCepsilon inhibitory peptide KP-1633. Adult male Wistar rats were exposed to CNH (10 % O(2), 3 weeks) or kept under normoxic conditions. The protein level of PKCepsilon and its phosphorylated form was analyzed by Western blot in homogenate, cytosolic and particulate fractions; the expression of PKCepsilon mRNA was measured by RT-PCR. The effect of KP-1633 on cell viability and lactate dehydrogenase (LDH) release was analyzed after 25-min metabolic inhibition followed by 30-min re-energization in freshly isolated left ventricular myocytes. Adaptation to CNH increased myocardial PKCepsilon at protein and mRNA levels. The application of KP-1633 blunted the hypoxia-induced salutary effects on cell viability and LDH release, while control peptide KP-1723 had no effect. This study indicates that PKCepsilon is involved in the cardioprotective mechanism induced by CNH.

The aim of this study was to compare the molecular characteristics of extractable soil carbon from biotopes of the Rašeliník watershed and dissolved organic carbon (DOC) from Rašeliník creek, by using the 0.1M pyrophosphate, 0.01M CaCl2 and Britton-Robinson buffer as extraction agents. The molecular weight Mr and weight-average molecular weight Mw, determined by the low pressure size exclusion chromatography, increased in the following sequence: humic substances (HS) in CaCl2 < aquatic HS < HS in sodium pyrophosphate ≤ HS in a buffer. Elution curves of all humic substances were characteristic by two peaks with predominant low-molecular fraction. Mr and Mw values of aquatic humic substances were 5.9 and 7.9 kDa, respectively, and proportion of this low-molecular fraction reached 97%. This corresponds to the fact, that the main fraction of HS in surface waters constitute fulvic acids. Using soil extraction in CaCl2 we obtained the fraction of organic carbon similar to the humic substances contain in DOC. Differences in quantity of humic substances extracted from soils among CaCl2 (mean 0.42 ± 0.39), Britton-Robinson buffer (34.9 ± 11.2) and sodium pyrophosphate (293.2 ± 113.4) were statistically significant. The A465/A665 ratio negatively correlated with molecular weight of humic substances.

The purpose of the present study was to assess the impact of brief daily reoxygenation during adaptation to chronic continuous hypoxia (CCH) on protective cardiac phenotype. Adult male Wistar rats were kept at CCH (10% oxygen) for 5, 15 or 30 days; a subgroup of animals was exposed to room air daily for a single 60-min period. While 5 days of CCH did not affect myocardial infarction induced by 20-min coronary artery occlusion and 3-h reperfusion, 15 days reduced infarct size from 62% of the area at risk in normoxic controls to 52%, and this protective effect was more pronounced after 30 days (41%). Susceptibility to ischemic ventricular arrhythmias exhibited reciprocal development. CCH increased myocardial abundance of mitochondrial superoxide dismutase (MnSOD) without affecting malondialdehyde concentration. Daily reoxygenation abolished both the infarct size-limiting effect of CCH and MnSOD upregulation, and increased malondialdehyde (by 53%). Ventricular cardiomyocytes isolated from CCH rats exhibited better survival and lower lactate dehydrogenase release caused by simulated ischemia/reperfusion than cells from normoxic and daily reoxygenated groups. The cytoprotective effects of CCH were attenuated by the large-conductance Ca2+-activated K+ (BKCa) channel blocker paxilline, while the opener NS1619 reduced cell injury in the normoxic group but not in the CCH group. Daily reoxygenation restored the NS1619- induced protection, whereas paxilline had no effect, resembling the pattern observed in the normoxic group. The results suggest that CCH is cardioprotective and brief daily reoxygenation blunts its salutary effects, possibly by a mechanism involving oxidative stress and attenuation of the activation of mitochondrial BKCa channels.

The magnetic sorbents with various contents of humic acids (ca. 6.6–15.5%) were prepared by a simple co-precipitation procedure from Fe 2+ /Fe 3+ salts and a commercially available alkaline humate concentrate. The sorbents were able to remove heavy metal cations (Cu 2+ ) from waters with the sorption capacity ranging from 0.006 to 0.25 mmol/g in dependence on the content of humic acids. An ability to remove some organic compounds (triazine and organophosphate pesticides) was also demonstrated. In both cases, the presence of humic acids in the sorbents plays a crucial role in the sorption process – whereas the sorption of metal cations was attributed to the presence of acidic functional groups, the sorption of (less polar) organic compounds was attributed to the presence of glassy-state polymeric domains in the iron-humate matrix. The iron-humate sorbents were effective also in the removal of inorganic phosphorus (phosphate anions) from water. In this case, however, the removal efficiency decreased with increasing content of humic acids in the sorbent. Although the saturation magnetization decreased proportionally with increasing content of humic acids, it remained still sufficiently high for all the examined sorbents to facilitate their effective separation in magnetic field.

Infants are born equipped to ingest nutrients, but have to learn how, what and how much to eat. This must occur early, because the mode of feeding evolves dramatically, from ‘tube’ feeding in utero to eating table foods with the family. Eating habits established during early years contribute to the development of subsequent eating habits. Therefore, it is fundamental to understand the most important early periods for the development of eating habits and the drivers of this development. Here we will focus on the first three years of postnatal life. Several characteristics of the eating experience contribute to drive infant’s eating and to shape preferences and energy intake control: food sensory properties; food energy density, social context of eating. The learning processes involve repeated exposure (including to a variety of flavours), association with post-absorptive consequences (energy density) and with contextual signals (interaction with family members). Beyond the first flavour discoveries during the prenatal and lactation periods (through the infant’s exposure to flavours from foods of the mother’s diet), the most important phases for learning food preferences and appetite control may be the beginning of complementary feeding. Infants discover the sensory (texture, taste and flavour) and nutritional properties (energy density) of the foods that will ultimately compose their adult diet; parents are still in charge of providing appropriate foods, timing, context for eating. Inter-individual differences in learning, related to temperamental dimensions, to sensitivity to food cues (sensory cues or energy density) are large and also have to be taken into account.

This study analyzes fatty acid (FA) composition in plasma lipids and erythrocyte phospholipids while comparing septic and non-septic critically ill patients. The aim was to describe impacts of infection and the inflammatory process. Patients with severe sepsis (SP, n = 13); age-, sex- and APACHE II score-matched non-septic critically ill with systemic inflammatory response syndrome (NSP, n = 13); and age-/sex-matched healthy controls (HC, n = 13) were included in a prospective case–control study during the first 24 h after admission to the intensive care unit. In both SP and NSP, lower n-6 polyunsaturated FA (PUFA) accompanied by higher proportions of monounsaturated FA (MUFA) in plasma phospholipids (PPL) was observed relative to HC. MUFA proportion was negatively correlated with n-6 PUFA, high density lipoprotein cholesterol (HDL-C), and albumin. MUFA was positively correlated with C-reactive protein (CRP), procalcitonin (PCT), interleukins (IL-6, IL-10), oxidized low density lipoproteins (ox-LDL), and conjugated dienes (CD). In both SP and NSP, inflammatory and lipid peroxidation markers were significantly higher—CRP (p

Despite being known more than 60 years, refeeding syndrome (RS) still bears many uncertainties. For example, its definition is not clear and definite, and the attitude to it varies from the complete neglect to over-prevention.The term "refeeding syndrome" refers to electrolyte and metabolic changes occurring in malnourished patients after the readministration of nutrition. These changes concern especially to phosphates and ions. Potassium, magnesium, naturism and fluids balance are involved. The changes lead to cell energetic metabolism and electric potential disturbances, with related clinical symptoms.Fully developed refeeding syndrome is quite rare; nevertheless it can be fatal for the patient. However, even its development can lead to many complications increasing the patient's morbidity and the length of stay in the hospital. Yet the refeeding syndrome is more or less predictable and if kept in mind also preventable.The aim of this article is to get the reader to know more about this metabolic phenomenon and possible attitudes towards it.

CD36 fatty acid translocase plays a key role in supplying heart with its major energy substrate, long-chain fatty acids (FA). Previously, we found that the spontaneously hypertensive rat (SHR) harbors a deletion variant of Cd36 gene that results in reduced transport of long-chain FA into cardiomyocytes and predisposes the SHR to cardiac hypertrophy. In the current study, we analyzed the effects of mutant Cd36 on susceptibility to ischemic ventricular arrhythmias and myocardial infarction in adult SHR- Cd36 transgenic rats with wild-type Cd36 compared with age-matched SHR controls. Using an open-chest model of coronary artery occlusion, we found that SHR- Cd36 transgenic rats showed profound arrhythmogenesis resulting in significantly increased duration of tachyarrhythmias (207 ± 48 s vs. 55 ± 21 s, P < 0.05), total number of premature ventricular complexes (2,623 ± 517 vs. 849 ± 250, P < 0.05) and arrhythmia score (3.86 ± 0.18 vs. 3.13 ± 0.13, P < 0.001). On the other hand, transgenic SHR compared with SHR controls showed significantly reduced infarct size (52.6 ± 4.3% vs. 72.4 ± 2.9% of area at risk, P < 0.001). Similar differences were observed in isolated perfused hearts, and the increased susceptibility of transgenic SHR to arrhythmias was abolished by reserpine, suggesting the involvement of catecholamines. To further search for possible molecular mechanisms of altered ischemic tolerance, we compared gene expression profiles in left ventricles dissected from 6-wk-old transgenic SHR vs. age-matched controls using Illumina-based sequencing. Circadian rhythms and oxidative phosphorylation were identified as the top KEGG pathways, while circadian rhythms, VDR/RXR activation, IGF1 signaling, and HMGB1 signaling were the top IPA canonical pathways potentially important for Cd36-mediated effects on ischemic tolerance. It can be concluded that transgenic expression of Cd36 plays an important role in modulating the incidence and severity of ischemic and reperfusion ventricular arrhythmias and myocardial infarct size induced by coronary artery occlusion. The proarrhythmic effect of Cd36 transgene appears to be dependent on adrenergic stimulation.

In order to understand the biological activity of humic substances (HS), the effect of four humic acids (HA) and one fulvic acid (FA) on seed germination and early growth of cosmopolitan weed Chenopodium album agg. were tested. Humic substances of diverse origin were used, namely purified commercial HA, HA isolated from lignite, cambisol and podzol, and FA from mountain spruce forest soil. Data processing by two-way ANOVA has shown that type of the tested substances was a more important factor on seed development than used concentration. The major differences in germination and length of shoots were found in the first days of the experiment. Commercial and lignite HA stimulated the seed germination and growth, while podzol HA inhibited them. After this initial phase, all humic substances stimulated the seed development, but these stimulations were not significant (P < 0.05). At the end of germination test, the greatest stimulation effect (up to 20%) was achieved with the lignite HA.

The adaptation to chronic hypoxia confers long-lasting cardiac protection against acute ischemia-reperfusion injury. Protein kinase C (PKC) appears to play a role in the cardioprotective mechanism but the involvement of individual PKC isoforms remains unclear. The aim of this study was to examine the effects of chronic intermittent hypoxia (CIH; 7,000 m, 8 h/day) and acute administration of PKC-δ inhibitor (rottlerin, 0.3 mg/kg) on the expression and subcellular distribution of PKC-δ and PKC-ε in the left ventricular myocardium of adult male Wistar rats by Western blot and quantitative immunofluorescence microscopy. CIH decreased the total level of PKC-ε in homogenate without affecting the level of phosphorylated PKC-ε (Ser729). In contrast, CIH up-regulated the total level of PKC-δ as well as the level of phosphorylated PKC-δ (Ser643) in homogenate. Rottlerin partially reversed the hypoxia-induced increase in PKC-δ in the mitochondrial fraction. Immunofluorescent staining of ventricular cryo-sections revealed increased co-localization of PKC-δ with mitochondrial and sarcolemmal membranes in CIH hearts that was suppressed by rottlerin. The formation of nitrotyrosine as a marker of oxidative stress was enhanced in CIH myocardium, particularly in mitochondria. The expression of total oxidative phosphorylation complexes was slightly decreased by CIH mainly due to complex II decline. In conclusion, up-regulated PKC-δ in CIH hearts is mainly localized to mitochondrial and sarcolemmal membranes. The inhibitory effects of rottlerin on PKC-δ subcellular redistribution and cardioprotection (as shown previously) support the view that this isoform plays a role in the mechanism of CIH-induced ischemic tolerance.

Protein kinase C (PKC) appears to play a significant role in the signal transduction of cardiac growth and development. The aim of this study was to determine changes in the total PKC activity and the expression of PKC isoforms alpha, delta and epsilon in the rat heart that was affected by pressure overload imposed at postnatal day (d) 2. Three groups of Wistar rats were employed for the experiment: rats submitted to the abdominal aortic constriction (AC), sham-operated controls (SO) and intact controls. Animals were sacrificed at d2, d3, d5 and d10. The total PKC activity was measured by the incorporation of (32)P into histone IIIS and the expression of PKC was analyzed by immunoblotting in the homogenate of the left ventricular myocardium and in the cytosolic, membrane-enriched (10(5) g) and nuclear-cytoskeletal-myofilament-enriched (10(3) g) fractions. We observed the significant transient increase in both the total PKC activity and the expression of all isoforms at d5 (the third day after the operation) in the cardiac homogenate of AC rats as compared with SO animals. Aortic constriction did not significantly affect the distribution of activity and isoform abundance among individual cellular fractions except for PKCdelta, which increased significantly at d10 in the cytosolic fraction at the expense of the membrane-enriched fraction. It is concluded that PKCalpha, PKCdelta and PKCepsilon undergo transient upregulation associated with the accelerated cardiac growth induced by pressure overload imposed in the very early postnatal period.

The effects of dietary supplementation with fat of different fatty acid profile and chronic intermittent hypoxia (CIH) on the fatty acid composition of serum and heart lipids were analysed. Adult male Wistar rats were fed a standard non-fat diet enriched with 10 % of lard, fish oil (n-3 PUFA) or maize oil (n-6 PUFA) for 10 weeks. After 4 weeks on the diets, each group was divided in two subgroups, either exposed to CIH in a barochamber (7000 m, twenty-five exposures) or kept at normoxia. In normoxic rats, the fish oil diet increased the level of conjugated dienes. Then-6:n-3 PUFA ratio in serum TAG, phospholipids (PL), cholesteryl esters (CE) and heart TAG, PL and diacylglycerols (DAG) followed the ratio in the fed diet (in the sequence maize oil>lard>fish oil). In heart TAG, PL and DAG, 20 : 4n-6 and 18 : 2n-6 were replaced by 22 : 6n-3 in the fish oil group. The main fatty acid in CE was 20 : 4n-6 in the lard and maize oil groups whereas in the fish oil group, half of 20 : 4n-6 was replaced by 20 : 5n-3. CIH further increased 20 : 5n-3 in CE in the fish oil group. CIH decreased then-6:n-3 PUFA ratio in serum CE, heart TAG, PL and DAG in all dietary groups and stimulated the activity of catalase in the maize and fish oil groups. In conclusion, PUFA diets and CIH, both interventions considered to be cardioprotective, distinctly modified the fatty acid profile in serum and heart lipids with specific effects on conjugated diene production and catalase activity.

In our screening, we aimed to detect phosphonates and other forms of organic phosphorus in basidiocarps and vegetative mycelia of six common basidiomycetes. Organic phosphorus-containing compounds were extracted in alkali and analysed using 31 P NMR. Monoesters, diesters, pyrophosphates and polyphosphates detected in high amounts reflected the high metabolic activity in basidiocarps (growth, production of basidiospores). Phosphonates were present in all samples, in concentrations ranging from 14 mg kg −1 of the extracted phosphorus in Boletus badius basidiocarp to 140 mg kg −1 in Amanita muscaria vegetative mycelium. Detection of phosphonates in basidiocarps together with our previous evidence from laboratory experiments support the fungal production of natural phosphonates in forest ecosystems.

The aim was to determine whether increased oxidative stress during the adaptation to chronic intermittent hypoxia (CIH) plays a role in the induction of improved cardiac ischemic tolerance. Adult male Wistar rats were exposed to CIH in a hypobaric chamber (7,000 m, 8 h/day, 5 days/wk, 24-30 exposures). Half of the animals received antioxidant N-acetylcysteine (NAC; 100 mg/kg) daily before the exposure; the remaining rats received saline. Control rats were kept under normoxia and treated in a corresponding manner. One day after the last exposure (and/or NAC injection), anesthetized animals were subject to 20 min of coronary artery occlusion and 3 h of reperfusion for determination of infarct size. In parallel subgroups, biochemical analyses of the left ventricular myocardium were performed. Adaptation to CIH reduced infarct size from 56.7 +/- 4.5% of the area at risk in the normoxic controls to 27.7 +/- 4.9%. NAC treatment decreased the infarct size in the controls to 42.0 +/- 3.4%, but it abolished the protection provided by CIH (to 41.1 +/- 4.9%). CIH decreased the reduced-to-oxidized glutathione ratio and increased the relative amount of PKC isoform-delta in the particulate fraction; NAC prevented these effects. The expression of PKC-epsilon was decreased by CIH and not affected by NAC. Activities of superoxide dismutase, catalase, and glutathione peroxidase were affected by neither CIH nor NAC treatment. It is concluded that oxidative stress associated with CIH plays a role in the development of increased cardiac ischemic tolerance. The infarct size-limiting mechanism of CIH seems to involve the PKC-delta-dependent pathway but apparently not the increased capacity of major antioxidant enzymes.

Fungal decomposition of and phosphorus transformation from spruce litter needles ( Picea abies ) were simulated in systems containing litter needles inoculated with individual saprotrophic fungal strains and their mixtures. Fungal strains of Setulipes androsaceus (L.) Antonin, Chalara longipes (Preus) Cooke, Ceuthospora pinastri (Fr.) Hohn., Mollisia minutella (Sacc.) Rehm, Scleroconidioma sphagnicola Tsuneda, Currah & Thormann and an unknown strain NK11 were used as representatives of autochthonous mycoflora. Systems were incubated for 5.5 months in laboratory conditions. Fungal colonization in systems and competition among strains were assessed using the reisolation of fungi from individual needles. After incubation, needles were extracted with NaOH and extracts were analysed using 31 P nuclear magnetic resonance spectroscopy (NMR). Needle decomposition was determined based on the decrease in C:N ratio. Systems inoculated with the basidiomycete S. androsaceus revealed substantial decrease in C:N ratio (from 25.8 to 11.3) while the effect of ascomycetes on the C:N ratio was negligible. We suppose that tested strains of saprotrophic ascomycetes did not participate substantially in litter decomposition, but were directly involved in phosphorus transformation and together with S. androsaceus could transform orthophosphate monoesters and diesters from spruce litter needles into diphosphates, polyphosphates and phosphonates. These transformations seem to be typical for saprotrophic fungi involved in litter needle decomposition, although the proportion of individual phosphorus forms differed among studied fungal strains. Phosphonate presence in needles after fungal inoculation is of special interest because no previous investigation recorded phosphonate synthesis and accumulation by fungi. Our results confirmed that the 31 P NMR spectroscopy is an excellent instrumental method for studying transformations of soil organic phosphorus during plant litter decomposition. We suggest that polyphosphate production by S. androsaceus may contribute to the phosphorus cycle in forest ecosystems because this fungus is a frequent litter colonizer that substantially participates in decomposition.

We examined the role of protein kinase C (PKC) in the cardioprotective mechanism induced by long-term adaptation to chronic intermittent hypoxia. Adult male Wistar rats were exposed to hypobaric hypoxia of 7,000 m for 8 h/day, 5 days/wk; the total number of exposures was 24–32. A control group was kept under normoxic conditions. Western blot analysis of PKC isoforms-δ and -ε was performed in the cytosol and three particulate fractions of left ventricular myocardium. Infarct size was determined in open-chest animals subjected to 20-min coronary artery occlusion and 3-h reperfusion. The PKC inhibitors chelerythrine (1 or 5 mg/kg) or rottlerin (selective for PKC-δ isoform; 0.3 mg/kg) were administered intravenously as a single bolus 15 min before ischemia. Chronic hypoxia had no effect on the expression and distribution of PKC-ε. The relative amount of PKC-δ increased in the cytosol and nuclear-cytoskeletal, mitochondrial, and microsomal fractions of chronically hypoxic myocardium by 100%, 212%, 237%, and 146%, respectively, compared with corresponding normoxic values. Chronic hypoxia decreased the size of myocardial infarction (normalized to the area at risk) by about one-third on the average ( P < 0.05). Both doses of chelerythrine tended to reduce infarction in controls, and only the high dose completely abolished the improvement of ischemic tolerance in hypoxic hearts ( P < 0.05). Rottlerin attenuated the infarct size-limiting effect of chronic hypoxia ( P < 0.05), and it had no effect in controls. These results suggest that chronic intermittent hypoxia-induced cardioprotection in rats is partially mediated by PKC-δ; the contribution of other isoforms remains to be determined.

Total protein kinase C (PKC) activity, its isoform expression, and concentration and fatty acid (FA) composition of diacylglycerol (DAG) were determined in the left ventricular myocardium of the rat during early postnatal development (d 2, 3, 5, 7, and 10). PKC activity measured by the incorporation of 32P into histone IIIS decreased between d 2 and 10 in the homogenate as well as in cytosolic, membrane (100,000 g), and nuclear-cytoskeletal-myofilament fractions (1000 g). Likewise, the expression of PKC isoforms (alpha, delta, and epsilon) determined by immunoblotting generally declined during the period analyzed, although with a variable pattern. In the membrane and nuclear cytoskeletal myofilament fractions, PKCdelta and PKCepsilon expression decreased markedly by d 3, returning to or close to the d 2 level immediately on d 5. PKCalpha expression in the membrane fraction remained almost unchanged by d 7, declining thereafter. PKCdelta and PKCepsilon were associated predominantly with particulate fractions, whereas PKCalpha was more abundant in the cytosolic fraction. DAG concentration exhibited a significant decline by d 5, consistent with the decrease in maximal PKC activity. The unsaturation index of FA in DAG tended to decrease on d 3 owing to the lowered proportion of all polyunsaturated FA of n-6 and n-3 series. These results demonstrate that the developmental decrease in PKC activity and expression in the rat myocardium is not linear and that subcellular localization of the enzyme exhibits isoform-specific day-by-day changes during the early postnatal period. These changes are compatible with the view that PKC signaling may be involved in the control of a rapid switch of myocardial growth pattern during the first week of life.

The aim of this study was to examine the effect of hypo- and hyperthyroidism on the phospholipid composition in developing rat heart. The hypothyroid state (PTU) was induced by 0.05% 6-n-propyl-2-thiouracil in drinking water given to nursing mothers from the postnatal day 2-21. The hyperthyroidism (T3) was made by daily injection of 3,3',5-triiodo-L-thyronine (10 microg/100 g body wt) to newborns in the same time period. Age matched intact littermates were taken as euthyroid controls. PTU decreased the concentration of total phospholipids (PL), choline phosphoglycerides (PC), ethanolamine phosphoglycerides (PE) and diphosphatidylglycerol (DPG) and increased the proportion of plasmalogen component of PE (PLPE). T3 increased the concentration of PL, PC, PE, DPG and decreased PLPE in comparison with euthyroid controls. The ratio of saturated/unsaturated fatty acids (FA) in PE was decreased in PTU and increased in T3 group. The ratio of n-6/n-3 polyunsaturated FA in PC, PE and phosphatidylinositol (PI) was increased in PTU due to increase of 18:2n-6 and decrease of 22:6n-3 proportion. T3 decreased this ratio because of decline in 20:4n-6 and rise in 22:6n-3 proportion. Both hypo- and hyperthyroidism decreased the ratio of 20:4n-6/18:2n-6 in the majority of phospholipids. PTU decreased the unsaturation index in PC, PI and phosphatidylserine. It is concluded that thyroid state plays an essential role in the development of membrane phospholipid components in cardiac membranes during the early postnatal period.

Possible enhancement of biodegradation of petroleum hydrocarbons in agricultural soil after tank truck accident (~5000 mg/kg dry soil initial concentration) by bioaugmentation of diesel degradingPseudomonas fluorescensstrain and addition of abiotic additives (humates, zeolite) was studied in a 9-month pot experiment. The biodegradation process was followed by means of analytical parameters (hydrocarbon index expressed as content of C10–C40aliphatic hydrocarbons, ratio pristane/C17, and total organic carbon content) and characterization of soil microbial community (content of phospholipid fatty acids (PLFA) as an indicator of living microbial biomass, respiration, and dehydrogenase activity). The concentration of petroleum hydrocarbons (C10–C40) was successfully reduced by~60% in all 15 experiment variants. The bioaugmentation resulted in faster hydrocarbon elimination. On the contrary, the addition of humates and zeolite caused only a negligible increase in the degradation rate. These factors, however, affected significantly the amount of PLFA. The humates caused significantly faster increase of the total PLFA suggesting improvement of the soil microenvironment. Zeolite caused significantly slower increase of the total PLFA; nevertheless it aided in homogenization of the soil. Comparison of microbial activities and total PLFA revealed that only a small fraction of autochthonous microbes took part in the biodegradation which confirms that bioaugmentation was the most important treatment.

Humic substances play an important role in many environmental processes such as sequestration and transport of hydrophobic compounds. The supramolecular character of humic substances imparts high flexibility of the aggregates associated with their variable reactivity under different conditions. In this study, heat-induced transitions and character of the hydration shell of sodium salts of humic and fulvic acids originating from various sources were investigated using ultrasonic velocimetry in the temperature interval from 5 to 90 °C. Results clearly showed differences in stability and characteristics of the hydrated states at concentrations above and below 1 g L −1 with the exception of Pahokee peat fulvic acids. It has been concluded that predominantly the relaxation part of the adiabatic compressibility plays an important role below 1 g L −1 in contrast to both relaxation and intrinsic parts of the compressibility being important at higher concentrations. Dilution brought several temperature induced transitions which were investigated with respect to composition of all investigated humic substances. Correlation analysis revealed that the transition around 17 °C is associated with disruption of H-interactions whereas the transition around 42 °C depends on the aromaticity. Comparison of cooling and heating records revealed hysteresis in the structural relaxation resembling the behavior of physically stabilized hydrogels. Results indicated a difference in the conformation and therefore reactivity of dissolved humic substances in the dependence on temperature and thermal history. It has been hypothesized that this may play an important role in the transport and sequestration of hydrophobic pollutants by dissolved organic matter.

Chronic intermittent hypoxia (CIH) is associated with increased production of reactive oxygen species that contributes to the adaptive mechanism underlying the improved myocardial ischemic tolerance. The aim was to find out whether the antioxidative enzyme manganese superoxide dismutase (MnSOD) can play a role in CIH-induced cardioprotection. Adult male Wistar rats were exposed to intermittent hypobaric hypoxia (7000 m, 8 h/day, 25 exposures) (n=14) or kept at normoxia (n=14). Half of the animals from each group received N-acetylcysteine (NAC, 100 mg/kg) daily before the hypoxic exposure. The activity and expression of MnSOD were increased by 66 % and 23 %, respectively, in the mitochondrial fraction of CIH hearts as compared with the normoxic group; these effects were suppressed by NAC treatment. The negative correlation between MnSOD activity and myocardial infarct size suggests that MnSOD can contribute to the improved ischemic tolerance of CIH hearts.

Disruption to the sensitive balance of long-chain fatty acids and glucose in the heart could cause cardiovascular diseases. Searching for a possible role of novel protein kinase C (nPKC) in heart with disrupted energy balance, we compared the insulin-resistant spontaneously hypertensive rats (SHR), which carry a nonfunctional variant of the fatty acid transporter FAT/CD36, with the less insulin-resistant congenic strain SHR-4 that is genetically identical except for a segment on chromosome 4 including a wild-type gene for a functional FAT/CD36. We analyzed expression of the nPKC-δ and -e isoforms plus triacylglycerols (TAG) content in the myocardium of both FAT/CD36 strains and after a high sucrose diet (HSD). Two weeks before killing, males of both strains were randomly divided into two groups and fed either a standard laboratory chow or an HSD. PKC was determined by Western blotting in particulate and cytosolic fractions from left ventricles. The SHR-4 rats exhibited lower serum levels of insulin and free fatty acids than did SHR rats and higher amounts of PKC-e in the heart particulate fraction. HSD caused accumulation of heart TAG in SHR but not in SHR-4. HSD increased PKC-δ and decreased PKC-e expression in particulate fraction from left ventricles of SHR-4 while having no effects in SHR. These results demonstrate that reduced insulin resistance in SHR-4 rats with wild-type FAT/CD36 is associated with the insulin signaling pathway involving nPKCs.

This study is a follow up of the investigation of some magnetic properties and metastability of greigite in samples obtained from Miocene claystones in the Krusne hory (Erzgebirge) Piedmont basins (Bohemia). Three different methods of upgrading the smythite were applied; the magnetic properties of the concentrates are compared. The thermal conversion of smythite sets in at 200°C while greigite converts at 250°C. The first intermediate products to be formed are iron sulphides, marcasite clearly dominating over pyrite and pyrrhotite. Apart from a Fe3+ sulphate with a composition of Fe2(SO4)3, oxidation of these sulphides gives rise to α-Fe2O3. The result of the subsequent decomposition of the mentioned sulphate is the formation of η-Fe2O3, which retains the sulphate structure. The final product of the thermal decomposition at 800°C is α-Fe2O3. In the smythite concentrate the conversion to Fe3+ sulphate and η-Fe2O3 is about twice as intensive as in greigite. No direct conversion to γ-Fe2O3 was found. During the thermal process self-reversals of remanence were observed, in various samples as many as four reversals in the temperature interval from 340 to 590°C. The occurrences of self-reversals of remanence were only observed at high degrees of thermal demagnetization, of the order of 10−2 down to 10−3 in the temperature interval of sulphide origin (below 400°C), and of the order of 10−4 down to 10−6 in the temperature interval of Fe-oxides origin (above 400°C).

The aim of this study was to determine the concentration of phospholipids (PL), plasmalogen components of choline (PC) and ethanolamine (PE) phosphoglycerides (PLPC, PLPE) and fatty acid profile of PL and triacylglycerols (TAG) in developing rat left ventricular myocardium between postnatal day (d) 2 and 100. The steepest increase of total PL (TPL) concentration occurs between d2 and d5, followed by a further slower increase between d20 and d40. Similar developmental changes were observed in PC and PE. The PLPE concentration rises by d10, whereas PLPC does not change during the whole period investigated, except for the transient decline on d5. The concentration of diphosphatidylglycerol (DPG) increases by d60; the steepest rise occurs between d20 and d40. Phosphatidylinositol (PI) concentration rises only by d5. The concentration of phosphatidylserine (PS) decreases between d5 and d10 and then it does not change. Sphingomyelin (SM) concentration is maintained till d10, it declines on d20 and does not change thereafter. The proportion of saturated fatty acids (SFA) increases by d5 in PC, PE, PS and TAG, and by d10 in DPG and PI. After d20 the SFA proportion gradually decline in all lipids. Monounsaturated FA (MUFA) proportion decreases in PC, PE, PI and PS from d2 till d10, and in the weaning period it tends to rise again. In contrast, in DPG and TAG the proportion of MUFA declines during the whole postnatal period. N-6 polyunsaturated FA (PUFA) decrease in all PL by d20 and rise again thereafter; in TAG they decline between d2 and d10 and return to the initial level by d100. N-3 PUFA increase in all PL during the suckling period and decline after weaning; in TAG they increase only by d5 and then they decline. This remodeling of myocardial PL and TAG composition during postnatal development may affect membrane properties and contribute to developmental changes in the function of membrane proteins and cell signaling.

VECKA, M., TVRZICKA, E., STAŇKOVA, B., NOVAK, F., NOVAKOVA, O. and ŽAK, A. Hypolipidemic Drugs Can Change the Composition of Rat Brain Lipids. Tohoku J. Exp. Med., 2004, 204 (4), 299-308 ││ Hypolipidemic drugs are potent serum cholesterol lowering agents used for prevention of coronary heart disease. In addition to their cholesterol lowering effect, these drugs exhibit both pleiotropic benefi cial and various neurological side effects. Therefore, we analysed effect of the hypolipidemic drugs, fenofibrate and statins, on membrane lipid composition in the rat brain tissue. Male Wistar rats were given 0.1 mg of fenofibrate, lovastatin, pravas tatin, fluvastatin or placebo (control) once daily for six weeks. In rats treated with lovastatin or pravastatin, decreased cholesterol and increased ceramide monohexoside contents in the brain tissue were observed in comparison with control. Treatment with fluvastatin or lovastatin resulted in increased sphingomyelin and decreased diphosphatidylglycerol contents. The most important changes in the fatty acid profile were observed in ceramide monohexosides; treatment with fluvastatin decreased the content of saturated and increased the content of polyunsaturated fatty acids. Fenofi brate treatment led to decreased content of saturated fatty acids in phosphatidylethanolamines. In conclusion, statin treatment resulted in the decreased content of cholesterol and diphosphatidylglycerol associated with the increased content of sphingolipids in the rat brain tissue. As cholesterol and sphingolipids are important components of brain membranes, the observed alterations in the composition brain lipids might be involved in genesis of neurological and mental symptoms following statin therapy. ││││ statin; fibrate; brain; lipids; fatty acid © 2004 Tohoku University Medical Press

Previous studies from our laboratory have indicated that secondary hyperaldosteronism affects phospholipids of rat colonic enterocytes. To assess whether this represents a direct effect of mineralocorticoids on enterocytes, the role of aldosterone and dexamethasone in the regulation of lipid metabolism was examined in Caco-2 cells during development of their enterocyte phenotype. Differentiation of Caco-2 cells was associated with increased levels of triglycerides (TG) and cholesteryl esters (CE), a decreased content of cholesterol and phospholipids and changes in individual phospholipid classes. The phospholipids of differentiated cells had a higher content of n-6 polyunsaturated fatty acids (PUFA) and lower amounts of monounsaturated (MUFA) and saturated fatty acids than subconfluent undifferentiated cells. Differentiated cells exhibited a higher ability to incorporate [3H]arachidonic acid (AA) into cellular phospholipids and a lower ability for incorporation into TG and CE. Incubation of subconfluent undifferentiated cells with aldosterone or dexamethasone was without effect on the content of lipids, their fatty acids and [3H]AA incorporation. In contrast, aldosterone treatment of differentiated cells diminished the content of TG, increased the content of phospholipids and modulated their fatty acid composition. The percentage of n-6 and n-3 PUFA in phospholipids was increased and that of MUFA decreased, whereas no changes in TG were observed. The incorporation of [3H]AA into phospholipids was increased and into TG decreased and these changes were blocked by spironolactone. Treatment of differentiated cells with dexamethasone increased their CE content but no effect was identified upon other lipids, their fatty acid composition and on the incorporation of [3H]AA. As expected for the involvement of corticosteroid hormones the mineralocorticoid and glucocorticoid receptors were identified in Caco-2 cells by RT-PCR. The results suggest that aldosterone had a profound influence on lipid metabolism in enterocytes and that its effect depends on the stage of differentiation. The aldosterone-dependent changes occurring in phospholipids and their fatty acid composition may reflect a physiologically important phenomenon with long-term consequences for membrane structure and function.

Previous studies have shown that aldosterone treatment of amphibian epithelial cells results not only in stimulation of Na + absorption but also in changes in phospholipid composition which are necessary for the mineralocorticoid action of aldosterone. The present study was designed to investigate the effect of aldosterone on phospholipids of mammalian epithelia. Phospholipid and fatty acid composition was examined in colonic epithelium (mineralocorticoid target tissue) and thymus (non-mineralocorticoid but glucocorticoid target tissue) of rats which had received aldosterone or vehicle by a miniosmotic pump for 7 days. Aldosterone increased the mass of colonic phospholipids relative to cellular proteins with concomitant changes in the percentage distribution of fatty acids, whereas the relative distribution of membrane phospholipds was not changed. Phosphatidylcholine increased the content of polyunsaturated and decreased that of monounsaturated fatty acids, which predominantly reflected the accretion of arachidonic and a decrease in oleic and palmitoleic acids. Within the phosphatidylethanolamine subclass, pretreatment of rats with aldosterone decreased the content of monounsaturated fatty acids (predominantly oleic and palmitoleic acid) and of n-3 fatty acids, and increased the content of saturated fatty acids (palmitic acid). The saturated-to-nonsaturated fatty acid ratio also significantly increased after aldosterone treatment. No changes in thymic phospholipids were seen. The results are consistent with the contention that aldosterone specifically modulates phospholipid concentration and metabolism in mineralocorticoid target tissue. The changes in phospholipid content and its fatty acid composition during the fully developed effect of aldosterone may reflect a physiologically important phenomenon with long-term consequences for membrane structure and function.

This study demonstrates the strong impact of photochemical degradation of soil dissolved organic matter (DOM) on its metal complexing capacity. The role of light in the fate of organically-bound metals transported from soils to surface waters was studied in laboratory experiments. We studied four humic and one fulvic acid isolates from different soil horizons in the Bohemian Forest (Czech Republic). Different concentrations of aluminium (Al) and iron (Fe) salts were added to the solutions of organic acids (initial dissolved organic carbon (DOC) concentration 0.5 mmol L(-1)), and the samples were irradiated in a reactor equipped with 350 nm irradiation lamps for 0 to 120 min. Aliquots of irradiated samples and dark controls were analyzed for DOC, ionic and organically-bound Al and Fe (Al(i), Fe(i), and Al(o), Fe(o), respectively), pH, and UV-VIS spectra. The initial Fe(o) concentrations in the samples (2.09 to 5.66 micromol L(-1)) decreased from 21 to 52% during irradiation, while the initial Al(o) concentrations (2.28 to 5.37 micromol L(-1)) decreased from 7 to 41%. The greatest decrease in the organically-bound metal concentrations occurred for the fulvic acid, and the smallest decrease occurred for the humic acid from the deepest soil horizon. The extrapolation of laboratory experiments to in situ conditions suggested that the DOM's ability to bind metals changes greatly within the first few hours after groundwater enters the stream. The rapid degradation of organically-bound Al and Fe can be an important process in first and second-order streams, and lake epilimnia.