Pal Kertai

Fungal siderophores function as protective agents of LDL oxidation and are promising anti-atherosclerotic metabolites in functional food.

Iron-mediated oxidation of low-density lipoprotein has been implicated in the pathogenesis of vascular disorders such as atherosclerosis. The present investigations were performed to test whether hydrophobic fungal siderophores - hexadentate trihydroxamates desferricoprogen, desferrichrome, desferrirubin, and desferrichrysin - might suppress heme-catalyzed LDL oxidation and the toxic effects of heme-treated LDL on vascular endothelium. Indeed, two of these - desferricoprogen and desferrichrome - markedly increased the resistance of LDL to heme-catalyzed oxidation. In similar dose-response fashion, these siderophores also inhibited the generation of LDL products cytotoxic to human vascular endothelium. When iron-free fungal siderophores were added to LDL/heme oxidation reactions, the product failed to induce heme oxygenase-1, a surrogate marker for the noncytocidal effects of oxidized LDL (not in the case of desferrichrysin). Desferricoprogen also hindered the iron-mediated peroxidation of lipids from human atherosclerotic soft plaques in vitro, and was taken up in the gastrointestinal tract of rat. The absorbed siderophore was accumulated in the liver and was secreted in its iron-complexed form in the feces and urine. The consumption of mold-ripened food products such as aged cheeses and the introduction of functional foods and food additives rich in fungal iron chelators in diets may lower the risk of cardiovascular diseases.

Incomplete chromatin condensation in enlarged rat myelocytic leukemia cells.

The distinguishable morphologic features of nuclei of acute myelogenous leukemia cells with enlarged size and finely distributed nuclear chromatin indicate incomplete chromosome condensation that can be related to elevated gene expression. To confirm this, interphase chromosome structures were studied in exponentially growing rat myelomonocytic leukemia 1 cells isolated at the University of Debrecen (My1/De cells). This cell line was established from primary rat leukemia chemically induced by 7,12-dimethylbenz[a]anthracene treatment. The enlarged nuclei of My1/De cells allowed improved fluorescent visualization of chromosomal structures. Increased resolution revealed major interphase intermediates consisting of (1) veil-like chromatin, (2) chromatin ribbon, (3) chromatin funnel, (4) chromatin bodies, (5) elongated prechromosomes, (6) seal-ring, spiral shaped, and circular chromosomal subunits, (7) elongated, bent, u- and v-shaped prechromosomes, and (8) metaphase chromosomes. Results confirmed the existence of the chromatin funnel, the first visible interphase chromosome generated by the supercoiling of the chromatin ribbon. Other intermediates not seen previously included the spiral subunits that are involved in the chromonemic folding of metaphase chromosomes. The existence of spiral subunits favors the helical coil model of chromosome condensation. Incomplete chromatin condensation in leukemia cells throughout the cell cycle is an indication of euchromatization contributing to enhanced gene expression and is regarded as a leukemic factor.

Lymphoid metastasis of rat My2/De leukemia

By grafting spontaneous leukemia tumor cells, the myeloid My2/De leukemia rat model was established. Death was caused by impaired functions of heavily infiltrated organs. In vitro culturing of tumor cells, blood and bone marrow counts and cytochemic reactions indicated the leukemic the origin resembling human myeoloblastic leukemia. Metastatic spread was followed after i.v. and i.p. injection, and by implantation of leukemia cells under the renal capsule of rats. Primary tumor and metastasis formation was visualized by (18)FDG or (11)C-methionine administration and MiniPET. The accumulation of radiotracers was measured in different organs and expressed as Differential Absorption Ratios (DARs). Subrenal implantation of My2/De cells resulted in their appearance in other abdominal organs and in parathymic lymph nodes. The release of tumor cells from the primary kidney to the peritoneum was mimicked by the i.p. administration of ink particles. Ink particles deposited in the abdominal organs and in the thoracal lymph nodes, preferentially in parathymic lymph nodes, confirming the notion of lymphatic spread of metastasis.

Metastatic hepatocarcinoma he/de tumor model in rat.

The aim of this study is to select among potential tumor models that could be suitable to follow the metastatic spead of tumor cells. 18FDG-PET tumor diagnostic test has been adapted to investigate tumor growth in vivo in local and metastatic rat models. Materials and Methods. The expression of glucose transporters was traced by immunohistological analysis, followed by the uptake of 18FDG and visualized by MiniPET scanner. After s.c. administration of hepatocarcinoma (He/De) cells intensive local tumor growth and 18FDG uptake were measured. Results: Whole body 18FDG-PET imaging supported by histological analysis have shown that subcutaneously growing tumors did not project metastases to other sites from the injected area. To avoid local tumor formation i.v. injection was chosen, but did not improve the safety of tumor cell administration. Tumor formation after i.v. injection took a longer time than after s.c. administration. Tumors upon i.v. generation were smaller and detectable in liver and lung, but not in other organs or tissues. iii) Subrenally implanted He/De cells spread from the retroperitoneal primary tumor of the kidney to thoracal paratymic lymph nodes (PTNs). The spread from primary site to metastatic tumors in PTNs was confirmed by post mortem surgery and histological examinations. Conclusion: Among the three methods applied: a) Local s.c. administration of tumor cells generated local tumors unsuitable to study metastasis. b) Intravenous administration causing unpredicatable location of tumor formation is not regarded a reliable metastatic tumor model. c) Subreanal implantation model proved to be a suitable model to follow the metastatic process in rats.

A comparative study on dyslipidaemia inducing diets in various rat strains

In our experiments we compared the serum lipoprotein lipid composition of Fischer 344 (F344) and Long-Evans (LE) inbred rats as well as of their hybrid FLF(1) from both sexes after feeding them for 2, 4 and 8 weeks with different diets. The following diets were used: 1) standard diet marked as CRLT/N; 2) diet reach in butter marked as BR; 3) diet containing cholesterol, sodium cholate and methylthiouracil marked as CR; 4) diet marked as BRC, which is the Hartroft-Sós diet modified by our research group consisting of the diets BR and CR. The latter diet was the most effective, because within two weeks the level of serum total cholesterol, LDL-cholesterol, HDL-cholesterol and triglyceride in the F344 female rats increased 8, 30, 4 and 8 times, respectively. The male rats of the Long-Evans strain showed moderately increased values while the FLF(1) female hybrids derived from the hybridization of LE males and F344 females had values closer to those of the mother strain. Despite the fact that during this time the LDL/HDL ratio increased from 0.06 to 2.97 and the PON-1 activity decreased to one-third, a significant lipid deposition could not be shown in the wall of the abdominal aorta even two months later. Our experimental model is suitable for the chemoprevention of dyslipidaemia or rapid testing of molecules chosen for its treatment.

Effects of fluvastatin and coenzyme Q10 on skeletal muscle in normo- and hypercholesterolaemic rats

Myalgia and muscle weakness may appreciably contribute to the poor adherence to statin therapy. Although the pathomechanism of statin-induced myopathy is not completely understood, changes in calcium homeostasis and reduced coenzyme Q10 levels are hypothesized to play important roles. In our experiments, fluvastatin and/or coenzyme Q10 was administered chronically to normocholesterolaemic or hypercholaestherolaemic rats, and the modifications of the calcium homeostasis and the strength of their muscles were investigated. While hypercholesterolaemia did not change the frequency of sparks, fluvastatin increased it on muscles both from normocholesterolaemic and from hypercholesterolaemic rats. This effect, however, was not mediated by a chronic modification of the ryanodine receptor as shown by the unchanged ryanodine binding in the latter group. While coenzyme Q10 supplementation significantly reduced the frequency of the spontaneous calcium release events, it did not affect their amplitude and spatial spread in muscles from fluvastatin-treated rats. This indicates that coenzyme Q10 supplementation prevented the spark frequency increasing effect of fluvastatin without having a major effect on the amount of calcium released during individual sparks. In conclusion, we have found that fluvastatin, independently of the cholesterol level in the blood, consistently and specifically increased the frequency of calcium sparks in skeletal muscle cells, an effect which could be prevented by the addition of coenzyme Q10 to the diet. These results support theories favouring the role of calcium handling in the pathophysiology of statin-induced myopathy and provide a possible pathway for the protective effect of coenzyme Q10 in statin treated patients symptomatic of this condition.