Guinea-pigs were maintained for 5 weeks on a diet containing three different concentrations of vitamin C: a) traces (none added), b) medium (0.05 % w/w) and high (0.5 % w/w). Twenty-four hours before killing the animals received one i.p. dose of 3 g ethanol per kg body weight (a model of short-term acute intoxication). In a parallel experiment which lasted 5 weeks, the animals were treated every week with two i.p. doses of 1 g ethanol per kg body weight followed bv the final acute intoxication (3 g ethanol/kg) (a model of long-term chronic alcoholization). In both experiments, the guinea-pigs with the highest tissue concentration of vitamin C proved to have significantly decreased residual levels of ethanol and acetaldehyde in the liver and the brain, a decreased activity of alanine- and aspartate aminoacyl transferases in the serum and decreased contents of triacylglycerols and cholesterol in the serum and liver in comparison with the vitamin C-unsupplemented group. The regression curve expressing vitamin C levels versus residual ethanol and acetaldehyde concentrations in the liver confirmed the highly significant negative correlation between them. Administration of the guinea-pigs with large amounts of vitamin C appears to accelerate ethanol and acetaldehyde metabolism and reduce some of their adverse health effects.
b1_Rats with diabetes induced by streptozotocin (STZ) and nicotinamide (NA) are often used in animal studies concerning various aspects of diabetes. In this experimental model, the severity of diabetes is different depending on doses of STZ and NA. Moreover, diabetic changes in rats with STZ-NA-induced diabetes are not fully characte rized. In our present study, metabolic changes and insulin secretion were investigated in rats with diabetes induced by administration of 60 mg of STZ and 90 mg of NA per kg body weight. Four to six weeks after diabetes induction, insulin, glucagon and some metabolic parameters were determined to evaluate the severity of diabetes. Moreover, insulin secretory capacity of pancreatic islets isolated from control and diabetic rats was compared. It was demonstrated that admi nistration of 60 mg of STZ and 90 mg of NA per kg body weight induced relatively mild diabetes, since insulin, glucagon an d other analyzed parameters were only slightly affected in diabetic rats compared with control animals. In vitro studies revealed that insulin secretory response was preserved in pancreatic islets of diabetic rats, however, was lower than in islets of control animals. This effect was observed in the presence of different stimuli. Insulin secretion induced by 6.7 and 16.7 mmol/l glucose was moderately reduced in islets of diabetic rats compared with control islets. In the presence of leucine with glutamine, insulin secretion appeared to be also decreased in islets of rats with STZ-NA-induced diabetes. Insulinotropic action of 6.7 mmol/l glucose with forskolin was also deteriorated in diabetic islets. Moreover, it was demonstrated that at a non-stimulatory glucose, pharmacological depolarization of plasma membrane with a concomit ant activation of protein kinase C evoked significant rise in insulin release in islets of control and diabetic rats., b2_However, in diabetic islets, this effect was attenuated. These results indicate that impairment in insulin secretion in pancreatic islets of rats with mild diabetes induced by STZ and NA result s from both metabolic and nonmetabolic disturbances in these islets., T. Szkudelski, A. Zywert, K. Szkudelska., and Obsahuje bibliografii a bibliografické odkazy
a1_The modern concept of causality of diseases emphasizes the study of natural defense functions of the organism and possibilities of influencing them, which will lead to effective prevention of these diseases. A great deal of information has been obtained on the system growth hormone (GH)/insulin-like growth factor (IGF)-I, which is of quite fundamental importance for the integrity of the organism. A dysbalance of the system may be the cause of diseases of the neonatal period, as well as diseases associated with aging. In old age, the synthesis of the crucial peptide system, IGF-I, declines as well as the sensitivity of tissues to this hormone. At the same time the changes in the expression of IGF-binding proteins (IGFBP) occur. Systemic growth factors are present in measurable concentrations in the circulation, they are, however, taken up or synthesized by some tissues, where they act as local cellular regulators. IGF-I is produced by many tissues, including bones under the control of estrogens, growth hormone and the parathyroid hormone. A decline of bone IGF-I in the cortical portion of bones is one of the many mechanisms leading to the development of involutional osteoporosis. Correlation studies, which have provided evidence of a relationship between the IGF system and the building of peak bone mass and its subsequent loss contributed to the understanding of the pathogenesis of this disease. It may be foreseen that the results of intervention studies focused on the effects of the recombinant IGF-I will also influence therapeutic and preventive approaches. Modern antiresorption pharmacotherapy stabilizes or enhances bone density and reduces the risk of fractures. The addition of effective anabolics might increase the effectiveness of treatment by shifting the remodeling equilibrium in favor of formative processes., a2_Because both recombinant GH and IGF-I have certain therapeutic limitations, it is considered to utilize substances which either stimulate endogenous IGF-I production directly in the bone or modulate synthesis and distribution of binding proteins for the peptide. Further new findings related to physiology and pathophysiology of this peptide will contribute to designing new strategies in the prevention of osteoporosis and other serious diseases of old age, such as diabetes, neoplasias or cardiovascular diseases., I. Žofková., and Obsahuje bibliografii
Autoři pojednávají o vitamínu D, který má mezi ostatními vitamíny specifické postavení, poněkud z jiného úhlu pohledu. Přibližují jeho evoluční původ a historii jeho objevování. Nedostatek vitaminu D vyvolává křivici, nemoc, která je doložena už od starověku. V této souvislosti upozorňují autoři na světově uznávané zásluhy významného, dnes už téměř zapomenutého českého vědce E. H. Kodíčka. Přehledně také popisují metabolismus a transport vitaminu D v organismu a upozorňují, že vitamin D také hraje důležitou úlohu při vzniku chronických nesdělných chorob, jejichž počet celosvětově stále vzrůstá., The authors discuss vitamin D, which has a special position among vitamins, from a somewhat different perspective. They clarify its evolutionary origin and the history of its discovery. A deficiency of vitamin D causes rickets, a disease that has been documented since antiquity. In this context, the authors draw attention to a nearly forgotten Czech scientist E. H. Kodíček of significant merit. They also briefly describe the metabolism and transport of vitamin D in the body and point out that vitamin D also plays an important role in the development of non-communicable chronic diseases, the number of which is increasing worldwide., and Petr Šíma, Bohumil Turek.
Resveratrol is a polyphenol found in different plant species and having numerous health-promoting properties in animals and humans. However, its protective action against deleterious effects of ethanol is poo rly elucidated. In the present study, the influence of resveratrol (10 mg/kg/day) on some hormones and metabolic parameters was determined in rats ingesting 10 % ethanol solution for two weeks. Blood levels of insulin, glucagon and adiponectin were affecte d by ethanol, however, resveratrol partially ameliorated these changes. Moreover, in ethanol drinking rats, liver lipid accumulation was increased, whereas resveratrol was capable of reducing liver lipid content, probably due to decrease in fatty acid synt hesis. Resveratrol decreased also blood levels of triglycerides and free fatty acids and reduced γ-glutamyl transferase activity in animals ingesting ethanol. These results show that resveratrol, already at low dose, alleviates hormonal and metabolic changes induced by ethanol in the rat and may be useful in preventing and treating some consequences o f alcohol consumption., K. Szkudelska, M. Deniziak, P. Roś, K. Gwóźdź, T. Szkudelski., and Obsahuje bibliografii
The activities of three enzymes involved in polyol biosynthesis (aldose reductase, AR; ketose reductase, KR; and polyol dehydrogenase, PDH) were studied in adult females of the linden bug, Pyrrhocoris apterus, collected from the field during 2005/2006. While the activities of three enzymes were low in reproductive females, activities greater by one or two orders were seen in reproductively arrested females. AR and KR showed similar seasonal trends in activity. Activities were low during diapause initation and later increased and stabilized during autumnal diapause development. Further increases of AR and KR activities were seen during low temperature quiescence and finally the activities sharply decreased during vernal resumption of direct development. The activity of PDH was relatively high (but fluctuating) during diapause, then decreased in quiescent insects and almost disapeared in reproductively active females. Insects collected in February were subjected to laboratory de-acclimation (exposure to high temperatures) followed by re-acclimation (exposure to low temperatures) which resulted in loss of activity in all three enzymes and no regain. High activities of AR, KR and PDH in reproductively arrested females thus conform well with their previously observed high capacity to synthesize and accumulate polyol cryoprotectants.
Suspension hypokinesia is a new model which can simulate some effects of microgravity on the organism of laboratory animals. Two groups of male SPF-bred Wistar rats were suspended for 24 h. In the first group hypokinesia began in the morning (M) (1 h after light onset, 0800 h), whereas the other group was subjected to this treatment from the evening (E) (1 h after dark onset, 2000 h). In the serum, there was a statistically significant increase in non-esterified fatty acids, triacylglycerols (TG) and glucose and a decrease in triiodothyronine concentration in the M group, while only a significant increase in phospholipids (PL) was found in the E group. The serum corticosterone level was increased in both groups, more markedly in the M group. There was an increase in TG and PL in the liver in M rats. In the bone marrow (femur), an increase of triglycerols in E rats and an increase of phospholipids in M rats were found. The concentration of glycogen in the heart muscle, m. quadriceps femoris and m. soleus rose in the M group only. The changes in the analyzed parameters predominate in the rats subjected to hypokinesia in the morning period. This fact confirmed the hypothesis about a higher sensitivity of rats to the stressor acting in the period of inactivity.