Reaction of Partially Methylated Polygalacturonic Acid with Iron(III) Chloride and Characterization of a New Mixed Chloride-Polygalacturonate Complex.

We have described a new route for the preparation of partially methylated polygalacturonic acid containing hydrolyzed (acidic) and unhydrolyzed (methyl esterified) carboxylate groups in a ratio of 1:1 (PGA, compound 1), and one of its basic FeIII-salts (compound 2) with a ~1:2 FeIII:GA stoichiometry (GA means galacturonic acid and methylated galacturonic acid units). The partially hydrolyzed pectin was transformed into compound 1 with the use of double ion exchange with a strongly acidic macroreticular sulfonated styrene-divinylbenzene copolymer as a hydrogen ion source. The reaction of compound 1 with FeCl3 resulted in compound 2. Compound 2 has a polymeric nature and contains binuclear FeIII(µ-O)(µ-OH)FeIII core units with two kinds of distorted octahedral iron geometries. The salt-forming acidic and methylated GA units of compound 1 are coordinated to FeIII centers in asymmetric bidentate-chelating and -bridging (via C=O group and glycosidic oxygen) modes, respectively. Two kinds of outer-sphere chloride anions were also detected by XPS in various chemical environments fixed by different sets of hydrogen bonds. We also observed a partial reduction of FeIII into FeII due to the ring-opening of the chain-end GA units of compound 1. This reaction provides a new route to determine the number of chain-ends in compound 2, and with the use of the number of GA units calculated from charge neutrality, the average length of these chains and the average molecular weight were also determined. The average molecular weight of the partially methylated polygalacturonic acid used in the industrial-scale production of commercial anti-anemic iron-polygalacturonate agents was ~50,000 g/mol. Compound 2 was also characterized by IR, Mössbauer, and X-ray photoelectron spectroscopy, and magnetic susceptibility measurements. These results on the structure and average molecular weight of basic iron(III) polygalacturonate provide a tool to design Fe-PGA complexes with tuned iron-releasing properties.

Microencapsulation and Application of Probiotic Bacteria Lactiplantibacillus plantarum 299v Strain.

Microencapsulation is an up-and-coming technology for maintaining the viability of probiotics. However, the effect of core-to-wall ratios and ratios of polysaccharides on the protection of the Lactiplantibacillus plantarum 299v strain has not been deeply discussed. Lyophilization of the Lp. plantarum 299v strain was conducted, and different core-to-wall ratios and ratios of maltodextrin (MD) and resistant starch (RS) were applied. Results demonstrated that the content of MD and RS had an influence on the yield and bulk density in both core-to-wall ratios (1:1 and 1:1.5). In addition, samples coated with a core-to-wall ratio of 1:1.5 had significantly higher viability than those coated with a core-to-wall ratio of 1:1. Moreover, samples coated with core-to-wall ratios of 1:1 and MD:RS 1:1, as well as core-to-wall ratios of 1:1.5 and MD:RS 3:1, had the highest cell number after simulated gastric fluid and simulated intestinal fluid testing, respectively. Furthermore, the optimal formulation for the application of microencapsulated Lp. plantarum 299v in apple juice (serving as a functional beverage) is listed as follows: core-to-wall ratios of 1:1 and MD:RS 1:1, with the fortification method, and stored at 4 °C. After 11 weeks of storage, the cell count was 8.28 log (CFU/mL). This study provided a strategy for Lp. plantarum 299v to achieve high viability in long-term storage and provides an application in functional apple beverages.

Effect of Two-Step Sous Vide Cooking and Storage on Microbiological and Oxidative Stability of Chicken Breast.

A two-step sous vide method, which included a low temperature initial stage, was shown to improve texture parameters, increase the solubility of proteins, and decrease the cook loss in chicken breasts. The current work was designed to determine the effect of two-step sous vide and subsequent storage on the microbiological and oxidative stability of chicken breasts. Inoculated chicken breasts were vacuum packaged and cooked at two temperatures, 50 °C and 60 °C, combined in different ratios of the same total cooking time (120 min), and then stored for 21 days at 4 °C, 10 °C, and -20 °C, and compared with the one-step temperature treatment (60 °C for 120 min). One-step sous vide treatment resulted in the total inactivation of Enterococcus faecalis NCAIM B. 01312. Meanwhile, the two-step sous vide treatments resulted in a higher than 3 log reduction in Enterococcus faecalis NCAIM B. 01312, reaching the target pasteurization performance criterion of sous vide for poultry meat. Lipid oxidation and the odor of all chicken breasts remained acceptable for 21 days of storage at 4 °C and -20 °C. Conversely, all chicken breasts had higher lipid oxidation rates and odor after 21 days of storage at 10 °C. Two-step-sous-vide-treated chicken breasts were found to be microbiologically stable regarding Enterococcus faecalis NCAIM B. 01312 and total mesophilic aerobic counts during 21 days of storage at 4 °C and -20 °C, in contrast with those stored at 10 °C. It can be concluded that two-step-sous-vide-cooked chicken breasts had acceptable oxidative and microbiological stability during chilled and frozen storage, similar to one-step sous vide ones. These outcomes highlight that two-step heat treatment can be used as an alternative cooking method to improve the quality properties without compromising the storage life of chicken breasts.

Spacer Layer Thickness Dependence of the Giant Magnetoresistance in Electrodeposited Ni-Co/Cu Multilayers.

Electrodeposited Ni65Co35/Cu multilayers were prepared with Cu spacer layer thicknesses between 0.5 nm and 7 nm. Their structure and magnetic and magnetoresistance properties were investigated. An important feature was that the Cu layers were deposited at the electrochemically optimized Cu deposition potential, ensuring a reliable control of the spacer layer thickness to reveal the true evolution of the giant magnetoresistance (GMR). X-ray diffraction indicated satellite reflections, demonstrating the highly coherent growth of these multilayer stacks. All of the multilayers exhibited a GMR effect, the magnitude of which did not show an oscillatory behavior with spacer layer thickness, just a steep rise of GMR around 1.5 nm and then, after 3 nm, it remained nearly constant, with a value around 4%. The high relative remanence of the magnetization hinted at the lack of an antiferromagnetic coupling between the magnetic layers, explaining the absence of oscillatory GMR. The occurrence of GMR can be attributed to the fact that, for spacer layer thicknesses above about 1.5 nm, the adjacent magnetic layers become uncoupled and their magnetization orientation is random, giving rise to a GMR effect. The coercive field and magnetoresistance peak field data also corroborate this picture: with increasing spacer layer thickness, both parameters progressively approached values characteristic of individual magnetic layers. At the end, a critical analysis of previously reported GMR data on electrodeposited Ni-Co/Cu multilayers is provided in view of the present results. A discussion of the layer formation processes in electrodeposited multilayers is also included, together with a comparison with physically deposited multilayers.

Comparison of techno-functional and sensory properties of sponge cakes made with egg powder and different quality of powdered blood products for substituting egg allergen and developing functional food.

Animal blood is a valuable resource, which is usually not utilized in a value-added way by the industry like other animal by-products, even though it has plenty of benefits in terms of sustainability and human health, particularly against iron deficiency anemia. Animal blood is perfectly suitable for providing special functions, which are necessary for functional foods, and improving techno-functional properties based on the previous reports published in the literature. In this paper, egg powder was substituted by powdered animal blood products (whole blood powder, blood plasma powder, and hemoglobin powder) in sponge cake. Techno-functional and sensory properties (texture by texture profile analysis and three-point breaking test, water activity, dry matter content, and color) were instrumentally measured and then a sensory evaluation was carried out by unskilled panelists. Quality characteristics (texture, color, and dry matter content) were daily measured on the day of baking and then every 24 h for 3 additional days because freshly baked cakes are usually consumed within 3 days. Based on the results, powdered blood products are suitable for substituting the egg powder in sponge cakes and developing functional foods. Blood powders can increase the hardness, chewiness, and breaking force of cakes, giving them the ability to be stuffed with more fillings and molded into special shapes without compromising on the sensory characteristics. They can also increase the intensity of the cocoa flavor, which results in a richer, darker color without deceiving the consumers.

Investigation of the effects of bovine collagen peptides and mixed berries on rheological properties and biological activity of egg white-based beverage via central composite design.

Modern consumer expectations have become highly diversified: they want more opportunities to meet diverse family needs (diversity of family members in age, gender, physical activity, etc. ,) and individual health goals with a huge variety of sensorial preferences. Our research is aimed to develop a protein-dense, highly bioactive, lactose- and whey protein-free beverage applying a central composite rotational design (CCRD) with 2 factors. For this purpose, an egg white-based beverage was flavored with mixed berries (factor A) and enriched with bovine collagen peptides (factor B). After suitable sample preparation, the rheological properties were investigated by an Anton Paar MCR 92 rheometer (with CC 27 system, and flow behavior was analyzed with a Herschel-Bulkley (H-B) model). The antioxidant capacity of samples was investigated by Ferric Reducing Antioxidant Power (FRAP) method, the total anthocyanin content was estimated based on a spectrophotometric method, and the total phenolic content was determined by the Folin Ciocalteu method. Our results are figured on response surfaces demonstrating that both factors and their interactions show a positive correlation with the examined parameters. Based on the CCRD, all investigated parameters are significantly influenced by at least one aspect and can be adequately estimated for further product development.

Spiegelmer-Based Sandwich Assay for Cardiac Troponin I Detection.

Two subunits of the ternary troponin complex, I and C, have cardiac muscle specific isoforms, and hence could be applied as highly-selective markers of acute coronary syndrome. We aimed at paving the way for the development of a robust cardiac troponin I-detecting sandwich assay by replacing antibodies with nuclease resistant aptamer analogues, so-called spiegelmers. To complement the previously generated spiegelmers that were specific for the N-terminus of cTnI, spiegelmers were selected for an amino acid stretch in the proximity of the C-terminal part of the protein by using a D-amino acid composed peptide. Following the selection, the oligonucleotides were screened by filter binding assay, and surface plasmon resonance analysis of the most auspicious candidates demonstrated that this approach could provide spiegelmers with subnanomolar dissociation constant. To demonstrate if the selected spiegelmers are functional and suitable for cTnI detection in a sandwich type arrangement, AlphaLisa technology was leveraged and the obtained results demonstrated that spiegelmers with different epitope selectivity are suitable for specific detection of cTnI protein even in human plasma containing samples. These results suggest that spiegelmers could be considered in the development of the next generation cTnI monitoring assays.

New Metabolic Influencer on Oxytocin Release: The Ghrelin.

BACKGROUND: The hypothalamic⁻pituitary axis by secreting neuropeptides plays a key role in metabolic homeostasis. In light of the metabolic regulation, oxytocin is a potential neuropeptide for therapies against obesity and related disorders. The aim of our study is to measure ghrelin-induced oxytocin secretion in rats and to detect the changes after administration of ghrelin antagonist. METHODS: Ghrelin was administrated centrally (intracerebroventricular, i.c.v., 1.0, 10.0, and 100.0 pmol) or systemically (intravenous, i.v., 1.0, and 10.0 nmol). [d-Lys³]-GHRP-6 ghrelin antagonist was injected 15 min before ghrelin injection in a dose of 10.0 pmol i.c.v. and 10.0 nmol i.v. RESULTS: Either i.c.v. or i.v. administration of ghrelin dose-dependently increased the plasma oxytocin concentration. Following pretreatment with the ghrelin antagonist [d-Lys³]-GHRP-6, the high plasma oxytocin level induced by ghrelin was significantly reduced. CONCLUSION: The results indicate that the release of oxytocin is influenced directly by the ghrelin system. Examination of the mechanism of ghrelin-induced oxytocin secretion is a new horizon for potential therapeutic options.

Ghrelin-Induced Enhancement of Vasopressin and Oxytocin Secretion in Rat Neurohypophyseal Cell Cultures.

The effects of ghrelin on vasopressin and oxytocin secretion were studied in 13-14-day cell cultures of isolated rat neurohypophyseal tissue. The vasopressin and oxytocin contents of the supernatant were determined by radioimmunoassay after a 1- or 2-h incubation. Significantly increased levels of vasopressin and oxytocin production were detected in the cell culture media following ghrelin administration, depending on the ghrelin doses. The oxytocin level proved to be more elevated than that of vasopressin. The increase of vasopressin and oxytocin secretion could be totally blocked by previous administration of the ghrelin receptor antagonist ([D-Lys3]-growth hormone-releasing peptide-6). Application of the ghrelin receptor antagonist after ghrelin administration proved ineffective. The results indicate that vasopressin and oxytocin release is influenced directly by the ghrelin system, and the effects of ghrelin on vasopressin and oxytocin secretion from the neurohypophyseal tissue in rats can occur at the level of the posterior pituitary. Our observations lend support to the view that neurohypophysis contains ghrelin receptors.

Endogenous Estrogen-Mediated Heme Oxygenase Regulation in Experimental Menopause.

Estrogen deficiency is one of the main causes of age-associated diseases in the cardiovascular system. Female Wistar rats were divided into four experimental groups: pharmacologically ovariectomized, surgically ovariectomized, and 24-month-old intact aging animals were compared with a control group. The activity and expression of heme oxygenases (HO) in the cardiac left ventricle, the concentrations of cardiac interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), the myeloperoxidase (MPO) activity in the cardiac left ventricle, and the effects of heme oxygenase blockade (by 24-hour and 1-hour pretreatment with tin-protoporphyrin IX, SnPP) on the epinephrine and phentolamine-induced electrocardiogram ST segment changes in vivo were investigated. The cardiac HO activity and the expression of HO-1 and HO-2 were significantly decreased in the aged rats and after ovariectomy. Estrogen depletion was accompanied by significant increases in the expression of IL-6 and TNF-α. The aged and ovariectomized animals exhibited a significantly elevated MPO activity and a significant ST segment depression. After pretreatment with SnPP augmented ST segment changes were determined. These findings demonstrate that the sensitivity to cardiac ischemia in estrogen depletion models is associated with suppression of the activity and expression of the HO system and increases in the secretion of proinflammatory cytokines and biomarkers.

Reliability of anthropometric parameters in the prediction of the visceral fat area among adult women.

Visceral fat accumulation is a risk factor for cardiometabolic diseases. Magnetic resonance imaging (MRI) and computed tomography (CT) provided the most accurate techniques of abdominal fat assessment, but these methods are very expensive. The aim of this study was to examine and compare the predictive ability of simple anthropometric parameters for visceral fat area (VFA) among adult women in different age and obesity status groups. The sample consisted of 133 adult women (aged 18-76 years). All subjects underwent anthropometric measurements. Body composition and VFA were determined with a multi-frequency bioimpedance analyzer (BIA). 16.9% of the younger women (age < 45) were obese with a body-mass index (BMI) > or = 30.0 kg/m2, and 23.2% of the older individuals (age > 45) had BMI > or = 30 kg/m2. After age and BMI adjustment, the best correlation was observed between VFA and waist circumference (WC) in younger women (R = 0.347, p = 0.002). In the case of the older women, the best correlation efficient values were for SAD (R = 0.560, p < 0.001) and hip circumference (R = 0.550, p < 0.001). The partial correlation coefficients were consistently higher for younger subjects with excessive fat accumulation (overweight & obese subgroup; individuals with WC > 80 cm) compared to women without obesity. Results of the multiple linear stepwise regression analyses showed the significance of age and BMI in prediction of VFA. In addition, hip circumference (HC) was one of the methods that best reflected VFA in older women independently from obesity status. Using single anthropometric parameters is not usually sufficient for predicting with good accuracy the VFA, but the convenient combination of these parameters could be a suitable way for the reliable prediction in Hungarian women.

The osmotically and histamine-induced enhancement of the plasma vasopressin level is diminished by intracerebroventricularly administered orexin in rats.

The effects of the centrally administered neuropeptides orexin-A on water intake and vasopressin (VP) secretion were studied in male Wistar rats (180-250 g). Different doses (10, 30, and 90 µg/10 µl) of the orexins and the specific orexin receptor-1 (OX(1)) antagonist SB 408124 (30 µg/10 µl) were administered intracerebroventricularly (i.c.v.) under anaesthesia, and the water consumption was measured during 6 h. A plasma VP level elevation was induced by histamine (10 mg/kg) or 2.5% NaCl (10 ml/kg) administered intraperitoneally (i.p.). The plasma VP levels were measured by radioimmunoassay. Increased water consumption was observed after the administration of 30 µg/10 µl orexin-A. There were no changes in basal VP secretion after the administration of different doses of the orexins. A significant increase in plasma VP concentration was detected following histamine administration. After 2.5% NaCl administration, there was a moderate VP level enhancement. Intracerebroventricularly administered orexin-A (30 µg/10 µl) blocked the VP level increase induced by either histamine or 2.5% NaCl administration. The inhibitory effects were prevented by the specific OX(1) receptor antagonist. In conclusion, the orexins increased water consumption. After 30 µg/10 µl orexin-A administration, the polydipsia was more pronounced. The OX(1) receptor antagonist significantly decreased the polydipsia. Histamine or hyperosmotic VP release enhancement was blocked by previously administered orexin. This inhibition was not observed following OX(1) receptor antagonist administration. Our results suggest that the effects of the orexins on water consumption or blockade of the histamine and osmosis-induced VP level increase are mediated by the OX(1) receptor.

Effects of orexin-monoaminergic interactions on oxytocin secretion in rat neurohypophyseal cell cultures.

The effects of orexin-monoaminergic compound interactions on oxytocin release were studied in 14-day rat neurohypophyseal cell cultures prepared by an enzymatic dissociation technique. The oxytocin contents of the supernatants were determined by radioimmunoassay. Following the administration of orexin-A or orexin-B in increasing doses, significant changes were not observed in the oxytocin content of the supernatant media. The oxytocin level increased substantially in response to adrenaline, noradrenaline, serotonin, histamine, dopamine or K(+) treatment. Preincubation with orexin-A or orexin-B reduced the adrenaline-, histamine- or serotonin-induced oxytocin level increases, but the oxytocin concentrations of the supernatant media remained above the control level. There was no significant difference in decreasing effect between orexin-A and orexin-B. Neither orexin-A nor orexin-B induced changes in oxytocin release following monoaminergic compound treatment. The results indicate that the changes in oxytocin secretion induced by the monoaminergic system can be directly influenced by the orexin system. The effects of orexin on oxytocin release can be antagonized by an orexin-1 receptor-specific antagonist. It may be presumed that the orexins can play a role in the pathogenetic process of metabolic diseases (e.g. obesity) by reducing the effects of increased oxytocin release caused by monoaminergic compounds. The interactions between the monoaminergic and orexin systems regarding oxytocin secretion occur at both the hypothalamic and the neurohypophyseal levels.

The effects of orexins on monoaminerg-induced changes in vasopressin level in rat neurohypophyseal cell cultures.

The effects of orexin-monoaminergic compound interactions on vasopressin release were studied in 14-day neurohypophyseal cell cultures from adult rats, prepared by an enzymatic dissociation technique. The vasopressin contents of the supernatants were determined by radioimmunoassay. Following administration of either orexin-A or orexin-B in increasing doses, significant changes were not observed in the vasopressin levels of the supernatant media. The vasopressin level substantially increased after epinephrine, norepinephrine, serotonin, histamine, dopamine or K(+) treatment. Preincubation with either orexin-A or orexin-B reduced the epinephrine-, histamine- or serotonin-induced increases in vasopressin level, but the vasopressin concentrations of the supernatant media remained above the control level. There was no significant difference in decreasing effect between orexin-A and orexin-B. Neither orexin-A nor orexin-B induced changes in vasopressin release following monoaminergic compound treatment. The results indicate that the changes in vasopressin secretion induced by the monoaminergic system can be directly influenced by orexin system. It may be presumed that the orexins can play a physiological role in the regulation of the water metabolism by reducing the effect of increased vasopressin release caused by monoaminergic compounds. The interactions between the monoaminergic and orexin systems regarding vasopressin secretion occur at both the hypothalamic and the neurohypophyseal level.

Inhibitory effect of galanin on adrenaline- and noradrenaline-induced increased oxytocin secretion in rat neurohypophyseal cell cultures.

The effects of the interactions between the 29 amino acid-containing peptide galanin and adrenaline or noradrenaline on the secretion of oxytocin were studied in 13- to 14-day cultures of isolated rat neurohypophyseal tissue. The alpha-receptor antagonist corynanthine blocked the adrenaline-induced increase of oxytocin secretion. When the beta-receptor antagonist propranolol was added before the noradrenaline treatment, the antagonist prevented the noradrenaline-induced enhancement of oxytocin release. Following the addition of galanin, the extent of oxytocin secretion into the supernatant medium decreased. Adrenaline and noradrenaline treatments increased the oxytocin level. Preincubation with galanin reduced the adrenaline- and noradrenaline-induced oxytocin level elevations. The blocking effect of galanin was prevented by previous treatment with the galanin receptor antagonist galantid (M15). When adrenaline or noradrenaline treatment was applied before galanin addition, the oxytocin secretion remained enhanced. The present results indicate that the changes in oxytocin secretion induced by the adrenergic system can be directly influenced by the galaninergic system. The interactions between the adrenergic and galaninergic systems from the aspect of oxytocin secretion can occur at the level of the posterior pituitary, independently of the hypothalamus.

Prevention of hypoxic brain oedema by the administration of vasopressin receptor antagonist OPC-31260.

The numerous situations which can result in cerebral hypoxic damage occur in newborn infants and in the elderly. In research aimed at more effective therapeutic intervention in ischaemic disorders of the brain, the animal model used and the principles of the causal therapy should be better outlined. The effects of the non-peptide AVPR (V2) antagonist 5-dimethylamino-1-[4-(2-methylbenzoylamino) benzoyl]-2,3,4,5-tetrahydro-1H-benzazepine hydrochloride (OPC-31260) on the cerebral oedema induced by general cerebral hypoxia were studied in rats. The general cerebral hypoxia was produced by bilateral common carotid ligation in Sprague-Dawley rats of the CFY strain. By 6h after the ligation, half of the rats had died, but the survival rate was significantly higher following OPC-31260 administration. Electron microscopic examinations revealed typical ischaemic changes after the carotid ligation, and OPC-31260 treatment did not significantly reduce the hypoxic signs in the brain cortex; only a certain decrease in the pericapillary oedema was observed. The carotid ligation increased the brain contents of water and Na(+) and enhanced the plasma AVP level. The increased brain water and Na(+) accumulation was prevented by OPC-31260 administration, but the plasma AVP level was further enhanced by OPC-31260. These results demonstrate the important role of AVP in the development of the disturbances in brain water and electrolyte balance in response to general cerebral hypoxia. The carotid ligation-induced cerebral oedema was significantly reduced following oral OPC-31260 administration. The protective mechanism exerted by OPC-31260 stems from its influence on the renal AVPR (V2). These observations might suggest an effective approach to the treatment of global hypoxia-induced cerebral oedema in humans.

The involvement of heme oxygenase-1 activity in the therapeutic actions of 5-aminosalicylic acid in rat colitis.

The mechanism of action of 5-aminosalicylic acid (5-ASA), the active therapeutic moiety of a number of clinically used anti-colitic agents, is unclear. The present study investigates whether the beneficial effects in vivo could involve induction of the heat shock protein, heme oxygenase-1 (HO-1), known to provide endogenous anti-oxidant and anti-inflammatory moieties which can modulate colonic inflammation. The effects of 5-ASA on the colonic expression and activity of HO-1 along with its effect on the inflammatory damage have been evaluated in the colitis provoked by instillation of trinitrobenzene sulphonic acid (TNBS) over 48 h in the rat. Intracolonic administration of 5-ASA (8, 25 and 75 mg/kg/day) dose-dependently reduced the TNBS-provoked macroscopic colonic inflammatory injury, myeloperoxidase (MPO) activity and TNF-alpha levels, while also dose-dependently increasing colonic heme oxygenase enzyme activity. Colonic HO-1 protein expression, determined by Western blot analysis in this colitis model, was likewise further induced by 5-ASA. Intracolonic administration of 5-ASA alone under unchallenged conditions also induced colonic HO-1 protein expression and stimulated heme oxygenase enzyme activity. Administration of zinc protoporphyrin (50 micromol/kg/day, s.c.), which prevented the increase in colonic heme oxygenase activity, abolished the anti-colitic effect of 5-ASA. These results suggest that 5-ASA may exert its colonic anti-oxidant and anti-inflammatory effects in vivo in part through the up-regulation of HO-1 enzyme expression and activity.

Modulation by heme and zinc protoporphyrin of colonic heme oxygenase-1 and experimental inflammatory bowel disease in the rat.

Reactive oxygen species, suggested to be involved in inflammatory bowel disease, may be modulated by endogenous anti-oxidant products of heme oxygenase-1 (HO-1). In the present work, HO-1 expression in trinitrobenzene sulphonic acid (TNBS)-induced colitis in the rat and the effects of HO-1 modulation, particularly by the HO-1 inducer, heme, were further evaluated. Colitis was induced by intracolonic challenge with TNBS and assessed macroscopically and by myeloperoxidase (MPO) assay. Heme oxygenase activity was determined by measurement of bilirubin formation and HO-1 protein expression was determined by Western blotting. TNBS challenge led to an early and substantial induction of HO-1 protein expression and heme oxygenase activity in the colon that peaked after 48-72 h and declined over 10 days. Heme (30 micromol/kg/day, s.c) increased colonic HO-1 protein expression and enzyme activity and decreased colonic damage and myeloperoxidase activity. Short-term administration of cadmium chloride (2 mg/kg, s.c.), another known HO-1 inducer, also reduced the colonic injury and myeloperoxidase levels. In contrast, the HO-1 inhibitor, zinc protoporphyrin (50 micromol/kg/day, s.c) significantly increased the colonic damage and myeloperoxidase activity over 10 days, as did tin protoporphyrin (30 micromol/kg/day, s.c). These results support the proposal that induction of HO-1 provides a protective mechanism in this model under both acute and more-chronic conditions, and that its selective up-regulation could thus be of therapeutic potential in colitis.

Biological half-life and organ distribution of [3H]8-arginine vasopressin following administration of vasopressin receptor antagonist OPC-31260.

The effects of the antidiuretic (V(2)) non-peptide receptor antagonist OPC-31260 on the plasma vasopressin level and the biological half-life and organ distribution of radiochemically pure, biologically active [(3)H]8-arginine vasopressin [spec. act.: 15.9 mCi/mmol (588 GBq/mmol)] were studied in Wistar rats. The plasma vasopressin level increased significantly throughout the whole experimental period (24 h). There was no change in the fast phase of the curves of total radioactivity disappearance from the plasma after the administration of [(3)H]arginine vasopressin (control: 1.51+/-0.17 min, OPC-31260-treated: 1.42+/-0.12 min, n=10). The fast phase of the disappearance curves of intact [(3)H]arginine vasopressin did not change either following the administration of OPC-31260 in a dose of 30 mg/kg p.o. (control: 1.06+/-0.19 min, OPC-31260-treated: 1.00+/-0.15 min, n=6). The slow phase of the biological half-life, which is characteristic for the examined compound, proved to be significantly longer (total radioactivity control: 9.29+/-0.61 min, OPC-31260-treated: 12.33+/-0.42 min, P<0.05, n=10; [(3)H]arginine vasopressin radioactivity: control: 5.96+/-0.58 min, OPC-31260-treated: 8.90+/-0.37 min, P<0.05, n=6). In the control rats, the radioactivity was accumulated to the greatest extent in the neurohypophysis, adenohypophysis and kidney. Following OPC-31260 administration, significantly more radioactive compounds accumulated in the kidney (control: 0.30+/-0.052 total radioactivity %/100 mg organ weight, OPC-31260-treated: 0.50+/-0.133 total radioactivity %/100 mg organ weight, P<0.05, n=10) and neurohypophysis (control: 0.37+/-0.053 total radioactivity %/100 mg organ weight, OPC-31260-treated: 0.52+/-0.076 total radioactivity %/100 mg organ weight, P<0.05, n=10). Our results permit the conclusion that the antidiuretic antagonist OPC-31260 not only blocks the V(2) receptors, but also increases the biological half-life of vasopressin. The longer biological half-life of vasopressin following OPC-31260 administration may play a role in the elevation of the plasma vasopressin level.