Zeitschrift fur Ernahrungswissenschaft最新文献

Circadian oscillations of liver tyrosine aminotransferase (TAT) tryptophan oxygenase (TO), alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), and glutamate dehydrogenase (GLDH) in temporal pattern of protein input have been investigated. Cosinor analysis of oscillations parameters revealed the glucocorticoid induction of TO activity and protein induction of TAT activity rhythm. ALAT, ASAT, and GLDH activities showed 24 h fluctuations, but the regulation mechanisms remain unclear.

A group of 26 children (13 boys and 13 girls; average age 12.2 years) with CD who had been on a gluten free diet for 5-15 years was examined in order to find out how effectively they could manage their diet. The diagnosis of CD was established on the basis of ESPGAN criteria (1969). 5-15 years ago. Antigliadin antibodies, IgG-, and IgA-AGA (by fluorescence enzyme immunoassay), Gliastick by ELISA technique, and Anti-endomysium antibodies (by indirect immunofluorescence on sections of monkey esophagus) were examined in the serum. Only 5 patients had no antigliadin or anti-endomysium antibodies. In 21 cases the IgG-AGA showed positive results; the IgA-AGA was positive in 6, the Gliastick in 19, and the anti-endomysium antibodies in 8 cases. The main cause of the mismanagement of the diet was inadequate food labeling; so it seems to be important to also establish a Food Intolerance Data Bank in Hungary. The 5 sero-negative children volunteered for a gluten challenge; 3 of them became positive in a few weeks or months. Two patients remained negative even after 1 year. Their gluten sensitivity may not prove to be permanent.

The acute phase response is the answer of the organism to disturbances of its physiological homeostasis. It consists of a local and a systemic reaction. The latter is characterized by dramatic changes in the concentration of some plasma proteins called acute phase proteins. Interleukin-6 (IL-6) has been identified in vitro and in vivo as the major hepatocyte stimulating factor. Subsequently, additional hepatocyte stimulating factors, such as leukemia inhibitory factor, oncostatin-M, interleukin-11 and ciliary neurotrophic factor have been discovered. IL-t and related cytokines belong to the so-called alpha-helical cytokine family characterized by four antiparallel helices. IL-6 and IL-6-type cytokines exert their action via plasma membrane receptor complexes consisting of specific cytokine binding subunits and a common signal transducing protein gp130. In this presentation we focus on structure/function studies of IL-6, its receptor subunits gp80 and gp130, the internalization of the ligand/receptor complex and a recently elucidated signal transduction pathway. We have shown that protein tyrosine kinases of the JAK family are associated with the cytoplasmic domain of gp130 and are activated in response to IL-6. Subsequently, the transcription factors--named STATs (signal transducers and activators of transcription)--STAT1 alpha and STAT3 are transiently recruited to the cytoplasmic domain of gp130, where they become tyrosine phosphorylated by JAK kinases. In addition to the tyrosine phosphorylation we have observed that IL-6 also induces a serine phosphorylation of STAT3. This modification occurs with a delayed time-course as compared to the tyrosine phosphorylation and is inhibited by the protein kinase inhibitor H7. We propose that the STAT3 serine phosphorylation is required for transactivation of IL-6 target genes which is also inhibited by H7.

In vivo, refeeding starved chickens stimulates transcription of the avian gene for malic enzyme in liver; in hepatocytes in culture, triiodothyronine (T3) and insulin stimulate transcription of this gene. In vivo, starvation, and in hepatocytes in culture, glucagon, medium-chain fatty acids (MCFA) and long-chain fatty acids (LCFA) inhibit transcription of the malic enzyme gene. We have defined a T3-response unit in the 5'-flanking DNA of the malic enzyme gene; it contains one major T3 response element and several minor ones; maximum responsiveness is dependent on the presence of all of these elements. LCFA probably act by inhibiting binding of T3 to its nuclear receptor. MCFA appear to act by a different mechanism. Inhibitory MCFA have chain lengths of six, seven or eight carbons; a common feature of other inhibitory compounds is that they can be metabolized to MCFA. Eight-carbon fatty acids with a hydroxyl on the 2- or 3-carbon are more potent inhibitors than octanoate, whereas 2-bromo-fatty acids and 2-hydroxy hexanoate are not inhibitory. In transfection experiments with a large variety of constructs derived from the malic enzyme 5'-flanking DNA, the ability of fatty acids to inhibit promoter function localizes to regions of DNA that contain T3REs. Promoter function of artificial T3REs also is inhibited by MCFA. Inhibition of promoter function using malic enzyme DNA is relatively constant in magnitude irrespective of the size of the T3 response. We postulate that MCFA directly regulates one of the functions of the T3 receptor.

We have previously reported that the induction of Vitamin A deficiency results in a threefold decrease in the hepatic expression of cellular retinol binding protein I (CRBP I) mRNA in vivo and that the treatment of intestinal cell lines in vitro with retinoids leads to the induction of CRBP I transcription. In the present paper we extend the analysis to retinoid-dependent gene expression in the testicular epithelium in vivo and in the intestinal cell line FRIC B. In rat testis excess Vitamin A results in the reduced production of mature spermatozoa and in the premature release of immature germ cells in the lumen, while Vitamin A deficiency leads to almost complete degeneration of the germinal epithelium. We show reduced level of expression of CRBP I mRNA in vitamin A deficient testis. Retinoid treatment of cultured intestinal cells, which induces a reorganization of the actin cytoskeleton, has no effect on the expression of the differentiation induced gene Dri 42. The results show that even though unable to trigger by themselves the differentiation process, retinoids exert a direct effect on the expression of specific genes.

In the tropics organisms have permanently adapted to deal with extremely high intensities of light, temperature and other environmental factors. Especially in coastal environments and fish farmings conditions can easily reach and exceed the tolerance limits of an organism. The UV-A band has been shown to be a potent modulator of light induced effects and general physiological functions in organisms. The biological endpoints and underlying mechanisms still have to be investigated. Our experiments were carried out with the easy to handle sub-tropical Convict-Cichlid fish (Cichlasoma nigrofasciatum) as a model organism. In our studies we observed that constant sub-lethal UV-A irradiation had a significant effect on the general metabolism and on the sensitivity towards other environmental stress factors in this fish. We found that, in addition to the depression of the general metabolism, sub-lethal UV-A irradiation in combination with elevated environmental temperature had a deleterious effect on the population. The threshold temperature for a sudden increase in mortality of the fish receiving the additional sub-lethal UV-A irradiation was 32 degree C. The fish were grown and adapted at 27-29 degrees C. A total of 78% of the fish receiving an additional UV-A irradiation died by high temperature stress while the reference population remained at a normal level (3%). The metabolic rate (MR) of the UV-A survivors during temperature stress was less than half the average value obtained in the reference population. After the environmental temperature returned below the apparent upper tolerance limit for this fish, the MR of UV-A population gradually increased to normal. Apparently a constant elevated sub-lethal dose of UV-A leads to the destabilization of an organism, making it more sensitive for other environmental stress factors. These observations seem to be important considerations in fish farming in the tropical and subtropical regions.

The investigation of the effectiveness of a diet supplemented with n-3 PUFA in children with glomerulonephritis was done. Patients receiving "Polyen" achieved better clinical remission, more rapid decrease of hypercholesterolemia, and hypercoagulation than the patients from the control group. We can recommend "Polyen" usage in the treatment of glomerulonephritis in children.

The influence of a diet supplemented with n-3 PUFA on the immune status of children with atopic dermatitis and asthma was investigated. The results of the investigation have shown the improvement of cell immunity along with a decrease in the clinical manifestation of the disease. n-3 PUFA could be used as immunocorrectors in combination with pathogenic treatment of children with allergic diseases.

Selenium (Se), an essential nutrient required for optimal growth of mammalian cells, affects the immune functions of a host in vivo. Utilizing a mouse model system and healthy human volunteers, we have shown that Se enhances the capacity of lymphocytes to respond to stimulation with mitogen or alloantigen, to proliferate, and to differentiate into cytotoxic effector cells. Supplementation with Se resulted in a significant increase in the tumor cytotoxicity of mouse cytotoxic lymphocytes, lymphokine activated killer cells and macrophages, and human cytotoxic lymphocytes and natural killer (NK) cells. Se also appears to abrogate the age-related deficiency of lymphocytes from an aged host to respond to stimulation by proliferation and differentiation into cytotoxic effector cells. These effects occurred in the absence of changes in the endogenous levels of interleukin-1, interleukin-2, or interferon-gamma, and were related to the ability of Se to enhance the expression of the alpha (p55) and/or beta (p70/75) subunits of the interleukin-2 receptor (IL-2R) on the surface of activated lymphocytes and NK cells. This resulted in a greater number of functional IL-2R/cell and in enhanced proliferation and clonal expansion of cytotoxic precursor cells. The molecular mechanism that mediates the effects of Se on immune cell function does not appear to be related to the function of Se as an antioxidant or to gene activation.

The occurrence of DNA-adduct-like indigenous compounds (I-compounds) was examined in tissue samples of rats differing in their microbial state and diet with or without pectins of different degrees of esterification (DE). For 21 days groups of six germfree and ten conventional rats were each fed either pectin-free or with diets containing 7.5% of three differently esterified pectin preparations (pectin A: DE 92.6%; pectin B: DE 70.8%; pectin C: DE 34.5%). DNA was isolated from colonic mucosa, liver, lung, kidney and measured by the highly sensitive 32P postlabelling assay for DNA adduct analysis. In germfree animals I-compounds were detected in all tissue samples after feeding the low-esterified pectin C. Under the higher-esterified pectins, A and B, a weak adduct formation could be demonstrated only in the liver, but not in the colonic mucosa, lung, and kidney. In conventional animals DNA adducts were found in all samples of colonic mucosa with the highest intensity in the control group, followed by the low-esterified pectin C group, and a weak intensity under the higher-esterified pectins A and B. The experiments show a tendency to a higher number and intensity of spots in the germfree compared with the conventional rats, in rats with a pectin-free compared with the pectin diet, and under the low-esterified compared with the higher-esterified pectins.