Experimental Biology and Medicine

All spongiform encephalopathies (SEs) result in brain disorders brought about by a slow virus. Since the origin of bovine SE (BSE), the infectious nature of the disease has been firmly established. Tubulofilamentous particles/scrapie termed nemavirus (NVP) and scrapie-associated fibrils (SAF) are ultrastructural markers, whereas protease-resistant protein (PrPsc) is a protein marker. The PrP molecules aggregate to form SAF. Each NVP consists of three layers: an outer protein coat, an intermediate ssDNA layer, and inner PrP/SAF. Therefore, ssDNA and PrP/SAF are physically associated with each other. The existence of at least 20 stable strains of SEs implies that a nucleic acid molecule serves as the information molecule. Animals inoculated with PrPsc do not develop the clinical disease, however, ssDNA purified from scrapie-hamster brains by alkaline gel electrophoresis mixed with binding proteins before inoculation developed the clinical disease. It appears that an “accessory protein” coded by the ssDNA of the NVP interacts with normal PrPc molecules, resulting in their conversion to PrPsc/SAF. The pathogenesis process in the infected animal, with increasing incubation periods, reveals that larger amounts of normal PrP molecules are modified to form SAF. This interferes with the normal supply of PrP to cell membranes, which become disrupted and eventually fragment, resulting in the vacuoles typical of those found in the SEs. Critical review of scientific literature has demonstrated that the agent contains a DNA genome.

Since cancer is the most common cause of death in the world population, the possibility that readily available natural substances from plants, vegetables, herbs, and spices may be beneficial in the prevention of cancer warrants closer examination. Saffron in filaments is the dried, dark red stigmata of Crocus sativus L. flowers and it is used as a spice, food colorant, and a drug in medicine. A growing body of research has demonstrated that saffron extract itself and its main constituents, the carotenoids, possess chemopreventive properties against cancer. This review discusses recent literature data and our results on the cancer chemopreventive activities of saffron and its main ingredients

Metallothioneins (MT) are low-molecular-weight, heat-stable, cysteine-rich proteins with four isoforms. MT-I and MT-II are ubiquitous and are induced by oxidative, physical, and chemical stress. MT-I is an efficient scavenger of superoxide (O2) and hydroxyl ion (OH–). We have demonstrated that O2 and hypohalous acid can cause an increase in glomerular albumin permeability (Palb) in vitro. The purpose of this study was to document the protective effect of MT gene product on the O2-mediated increase in Palb. Glomeruli from Sprague-Dawley rats in 4% BSA medium were incubated for 4 hr at 37°C in duplicate tubes. Each set contained glomeruli alone or with 5 μM Cd++, 0.3 mM Spermine-NONOate (NO donor), 0.3 mM Sulfo-NONOate (nitrous oxide donor), 0.6 mM SNP (nonspecific NO donor) and SNP + carboxy-PTIO (10 mg/ml). After incubation, one set of tubes was used to isolate total RNA for the measurement of the mRNA levels of MT-I by reverse transcriptase polymerase chain reaction (RT-PCR). Duplicate tubes were incubated for an additional 10 min with 10 nM of O2, and Palb was measured using video microscopy. RT-PCR of total RNA from Cd++ and Spermine-NONOate treated glomeruli revealed a 2-fold induction of MT-I expression at the mRNA level. O2 caused a significant increase in Palb (0.8 ± 0.06 vs. control 0.0 ± 0.12, P < 0.05) and induction of MT-I in glomeruli by Cd++ or by Spermine-NONOate blocked this effect (0.21 ± 0.12 and 0.24 ± 0.19, respectively, P < 0.05 vs. O2). In contrast, Sulfo-NONOate and SNP did not induce mRNA for MT-I in glomeruli and did not provide protection against O2-mediated increase in Palb We conclude that MT-I gene products may play an important role in protecting the glomerular filtration barrier from the injury induced by reactive oxygen species in immune and/or nonimmune renal diseases

Studies were carried out primarily to assess the role of insulin in regulating iodide uptake in the mammary gland. Using cultured mammary gland explants from virgin and pregnant mice (12–14 days into gestation), insulin (1 μg/ml) was shown to stimulate iodide uptake after a 2-day exposure period. The effect of insulin was manifested by itself, as well as in the presence of cortisol and prolactin. Optimal iodide uptake was observed when tissues were treated with all three lactogenic hormones (insulin, cortisol, and prolactin). In a time-course experiment, the effect of insulin alone was initially observed after a 10-hr treatment; the effect was maintained for 30 hr. In dose-response studies, 1 ng/ml insulin elicited a significant effect after 24 hr in culture; a maximal effect was achieved with 50–100 ng/ml insulin. The optimal cortisol concentration for a maximum stimulation of iodide uptake was 10–7M. In a quantitative Western blot analysis employing an antibody to the sodium-iodide symporter, insulin stimulated an upregulation of the transporter protein after a 4-, 8-, or 20-hr treatment with insulin. Perchlorate and thiocyanate abolished the insulin effect on iodide uptake, further suggesting that the insulin response occurs via a stimulation of the sodium-iodide symporter. Clearly, insulin is an important and essential hormone in the lactogenic hormone complex for regulating iodide uptake in the mammary gland, but maximal expression of iodide uptake is only expressed when all three lactogenic hormones are present.

The release of Ca2+ from intracellular stores is a fundamental element of signaling pathways involved in regulation of vascular tone, proliferation, apoptosis, and gene expression. Studies of sea urchin eggs have led to the identification of three functionally distinct Ca2+ signaling pathways triggered by IP3, cADPR, and NAADP. The coexistence and functional relevance of these distinct intracellular Ca2+ release systems has only been described in a few mammalian cell types. The purpose of this study was to determine whether the IP3, cADPR, and NAADP Ca2+ release systems coexist in smooth muscle cells (SMC) and to determine the specificity of these intracellular Ca2+ release pathways. Microsomes were prepared from rat aortic SMC (VSMC) and were loaded with 45Ca2+. cADPR, NAADP, and IP3 induced Ca2+ release from VSMC microsomes in a dose-dependent fashion. Heparin blocked only IP3-mediated Ca2+ release, whereas the ryanodine channel inhibitors 8-Br-cADPR and ruthenium red blocked only cADPR-induced Ca2+ release. Nifedipine, an L-type Ca2+ channel blocker, inhibited NAADP elicited Ca2+ release, but had no effect on IP3- or cADPR-mediated Ca2+ release. An increase in pH from 7.2 to 8.2 inhibited cADPR-mediated Ca2+ release, but had no effect on IP3- or NAADP-induced Ca2+ release. By RT-PCR, VSMC expressed ryanodine receptor types 1, 2, and 3. Ca2+-dependent binding of [3H]-ryanodine to VSMC microsomes was enhanced by the ryanodine receptor agonists 4-chloro-methyl-phenol (CMP) and caffeine, but was inhibited by ruthenium red and cADPR. We conclude that VSMC possess at least three functionally distinct pathways that promote intracellular Ca2+ release. IP3-, cADPR-, and NAADP-induced intracellular Ca2+ release may play a critical role in the maladaptive responses of VSMC to environmental stimuli that are characteristically associated with hypertension and/or atherogenesis.

Freshwater (FW) teleosts are capable of acclimating to seawater (SW) following such a transfer from FW. However, their osmo-regulating mechanisms are still unclear, particularly those in the brain. The present study was conducted to examine acute changes that occur in brain Na+-K+-ATPase activity, creatine kinase (CK) activity, creatine, creatinine contents, and ATP levels of tilapia (Oreochromis mossambicus) in response to this transition. After transfer to SW (25 ppt), the Na+-K+-ATPase activity was maintained for 8 hr at higher levels than that in FW. In contrast, in 35 ppt SW, Na+-K+-ATPase was maintained at a even higher level than in FW for the first 2 hr. Brain Na+-K+-ATPase contents in both the 25 and 35 ppt SW groups were significantly elevated within 1 and 0.5 hr after transfer from FW, respectively. Interestingly, brain CK activities and content (homodimer of the B subunit [BB] form) in both the 25 and 35 ppt SW groups were significantly elevated within 1 hr after transfer from FW. The ATP contents in 35 ppt SW increased abruptly within 0.5 hr, and then gradually decreased during the next 2 hr. Unlike the 35 ppt group that declined in ATP contents, the 25 ppt group leveled off within 24 hr. The elevations in CK activity and creatine levels after transfer from FW to SW imply that abrupt salinity changes alter phosphocreatine/CK ratio. Such changes are needed to satisfy the increases in the energetic requirement of the cotransport mechanisms mediating osmoregulation

In vitro effects of catechins and their oligomers linked by C4 → C8 bonds are major antioxidative components of chocolate and cocoa. Their effects on the susceptibility of human low-density lipoprotein (LDL) to oxidation were evaluated. The strength of the antioxidative activity was measured using copper ions as the radical generator as compared by weight varied in the following order: (+)-catechin > procyanidin B2 ≥ (–)-eplcatechin ≥ procyanidin C1 > cinnamtannin A2. Using 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrlle) (MeO-AMVN) as the radical generator, the order was (–)-epicatechin ≥ procyanidin B2 ≥ procyanidin C1 > (+)-catechin ≥ cinnamtannin A2. It is suggested that these compounds contribute to the activity of cacao products to protect LDL from oxidation.

The heterotopically induced ossicles are used in our research on bone tissue. The ossicles are formed in the thigh muscle of BALB/c mice under the influence of injected suspension of 3 × 106 HeLa cells. We postulate that the mechanism of bone induction is based on the secretion of bone morphogenetic proteins BMP-4 and BMP-6 by the grafted HeLa cells. This was proved by the use of specific immunohistochemical reaction and Western blots of conditioned culture medium. It seems that HeLa cells secrete BMPs continuously into the culture medium, even without contact with the mice muscle tissue, were induction of bone tissue is observed.

Hypothalamic neuronal histamine has been shown to regulate feeding behavior and energy metabolism as a target of leptin action in the brain. The present study aimed to examine the involvement of l-histidine, a precursor of neuronal histamine, in the regulation of feeding behavior in rats. Intraperitoneal (ip) injection of l-histidine at doses of 0.35 and 0.70 mmol/kg body weight significantly decreased the 24-hr cumulative food and water intakes compared to phosphate buffered saline injected controls (P < 0.05 for each). This suppression of feeding was mimicked dose-dependently by intracerebroventricular infusion of histidine at doses of 0.5, 1.0, and 2.0 μmol/rat (P < 0.05 for each). Pretreatment of the rats with an ip bolus injection of α-fluoromethylhistidine, a suicide inhibitor of a histidine decarboxylase (HDC), at a dosage of 224 μmol/kg blocked the conversion of histidine into histamine and attenuated the suppressive effect of histidine on food intake from 64.2% to 88.1% of the controls (P < 0.05). Administration of 0.35 mmol/kg histidine ip increased the concentration of hypothalamic neuronal histamine compared with the controls (P < 0.05). HDC activity was increased simultaneously by histidine administration compared with the controls (P < 0.05). The present findings indicate that l-histidine suppresses food intake through its conversion into histamine in the hypothalamus