Specific induction of uncoiling in NORs of human acrocentric chromosomes by 5-azacytidine and 5-azadeoxicytidine

The organization of rDNA-containing chromatin was analysed by transmission electron microscopy after treatment of cultured human lymphocytes with 5-azacytidine (ACR) or 5-azadeoxicytidine (AdCR). The number of observed acrocentric chromosomes with satellites was significantly increased after treatment with low doses of ACR or AdCR during the last 24 h of culture, whereas with exposures during the last 7 h the number remained normal. The results suggest that the incorporation of ACR and AdCR in the early period of the S-phase may have reverted the non-satellized to satellized chromosomes. The cytidine analogues may have become more visible during secondary constriction thus changing the NOR structure leading to an increased number of satellized chromosomes.     

Mycotoxins as a cause of disease in human beings

Secondary metabolites, toxic to macro-organisms and micro-organisms, are produced by certain molds and some plant parasitic living fungi. A risk is given for man worldwide by ingestion or apparently also be other routes always undetected. In vivo-effects of the various mycotoxins are different, but mainly the liver is affected, expecially by the intake of smaller amounts of these poisons. Accordingly cirrhosis of the liver or primary liver carcinoma are expected in man as well as in animals and were already proved outside of Europe.     

Free-roaming and feral cats--their impact on wildlife and human beings

The possibility of the translocation of the enzyme across the phospholipid bilayer membrane was investigated by using the liposomes prepared by 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) in which beta-galactosidase (beta-gal) was entrapped. Exposing the POPC liposomes entrapping beta-gal inside to heat treatment (40-50 degrees C, 1-60 min) was found to induce its translocation across the liposome membrane. The translocated activity of beta-gal from inner to outer aqueous phase of liposomes indicated the maximal value when the liposomes entrapping beta-gal were heated at 45 degrees C for 30 min. The gel permeation profiles of the liposomes before and after heat treatment (45 degrees C, 30 min) also supported the translocation of beta-gal across the liposome membrane. The membrane fluidity of liposomes was found to be increased with increasing temperature, so that the hydrophobicity of liposome membrane was also increased. The local hydrophobicity of beta-gal was maximized at the temperature of 40-50 degrees C. The mechanisms of beta-gal translocation have been suggested to be triggered by the enhancement of hydrophobic interaction between the liposome surface and beta-gal molecules. Finally, a minimal scheme of possible mechanism on the heat-induced translocation of beta-gal has been presented on the basis of the hydrophobic interaction between the liposome and the proteins. The experimental data on the heat-induced translocation of beta-gal were well corresponding to those from model calculation.     

Instrumental conditioning of autonomically mediated responses in human beings.

Reviews foundations of the belief that autonomically mediated responses are not instrumentally modifiable in the work of Jerzy Konorski, Stefan Miller, and Skinner. Later research confirming the conditionability of the human galvanic skin response is cited, along with confirmation of the reliability of instrumental heart rate conditioning. Implications for basic conditioning theory and for the treatment of psychosomatic disorders are noted. A revision of the traditional categories of conditioning is suggested. (74 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simultaneous determination of omeprazole and 5''-hydroxyomeprazole in human plasma by liquid chromatography-tandem mass spectrometry

Tri-, tetra-, and penta-saccharide fragments of the O-specific polysaccharide of Shigella dysenteriae type 1 have been prepared in which a D-galactose residue of each oligosaccharide methyl glycoside derivative contains a 13C label at C-1. The interglycosidic coupling constants (3JCH) of these 13C nuclei with the H-3 nuclei of the adjacent 2-acetamido-2-deoxy-D-glucose residues have been measured by two-dimensional, J-resolved 1H NMR spectroscopy. The magnitudes of these coupling constants indicate that the trisaccharide is conformationally different to the higher oligosaccharide homologs, in agreement with previous studies of 13C chemical shifts and 1JCH values.     

Effects of nimesulide on constitutive and inducible prostanoid biosynthesis in human beings

BACKGROUND: The aim of this study was to test the hypothesis that nimesulide, a nonsteroidal antiinflammatory drug, or its principal metabolite 4-hydroxynimesulide, is a selective inhibitor of prostaglandin H synthase-2 in human beings. METHODS: Heparinized whole blood samples obtained from healthy subjects were incubated with lipopolysaccharide (10 micrograms/ml) for 24 hours at 37 degrees C and prostaglandin E2 was measured in plasma as an index of monocyte prostaglandin H synthase-2 activity. The production of thromboxane B2 in whole blood allowed to clot at 37 degrees C for 60 minutes was assessed as an index of platelet prostaglandin H synthase-1 activity. We also measured the urinary excretion of 11-dehydrothromboxane B2, prostaglandin E2, 6-ketoprostaglandin F1 alpha, and thromboxane B2 as in vivo indexes of cyclooxygenase activity. All prostanoids were measured by previously validated radioimmunoassay techniques. RESULTS: In the whole blood assays in vitro, nimesulide was twentyfold more potent than 4-hydroxynimesulide toward the two isozymes and both compounds displayed a twentyfold preference for prostaglandin H synthase-2 versus prostaglandin H synthase-1. The administration of a single oral dose of 100 mg nimesulide to six healthy subjects significantly (p < 0.01) reduced monocyte prostaglandin H synthase-2 and prostaglandin H synthase-1 activity ex vivo by more than 90% and 50%, respectively, up to 6 hours. At 24 hours, prostaglandin H synthase-2 but not prostaglandin H synthase-1 activity was significantly reduced by 49% (p < 0.05). Nimesulide significantly (p < 0.05) reduced the urinary excretion of 11-dehydrothromboxane B2 and 6-ketoprostaglandin F1 alpha by approximately 30% and 25%, respectively, while not affecting that of prostaglandin E2 and thromboxane B2. CONCLUSIONS: Nimesulide is a potent inhibitor of human monocyte prostaglandin H synthase-2. However, despite a twentyfold selectivity ratio, therapeutic plasma levels of nimesulide are sufficiently high to cause detectable inhibition of platelet prostaglandin H synthase-1.     

Partial reinforcement effects in classical aversive conditioning in rabbits and human beings.

Investigated the partial reinforcement extinction effect (PREE) in classical aversive conditioning. In Exp I the nictitating membrane responses of approximately 120 naive New Zealand rabbits were conditioned at a 250-msec interstimulus interval under continuous reinforcement, partial reinforcement with the unconditioned stimulus (UCS) omitted (Group PO), or partial reinforcement with the UCS delayed to 1,500 msec (Group PD). These 3 groups were factorially extinguished under UCS-omitted, UCS-unpaired, or UCS-delayed extinction regimens. A significant PREE was obtained, but only for PO training and UCS-omitted extinction. Exp II, employing 50 undergraduates in a masked eye blink conditioning task, produced parallel results. A general discrimination view of the classical PREE seems applicable, but one in which neither cognitive factors nor intertrial conditioning of reinforcement aftereffects plays a significant role. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Specific tolerance induction and transplantation: a single-day protocol

Bone marrow transfusion is a well-established method for induction of mixed hematopoietic chimerism and donor-specific tolerance in animal models. This procedure, however, is inapplicable in clinical transplantation using cadaveric donors due to the interval (1 week to 7 months) between tolerance induction and organ transplantation. For clinical use, it is essential that allografts be placed at the time of bone marrow transfusion. In the present study, we performed skin transplantation within 1 hour after a nonlethal conditioning regimen. Recipient mice were treated with anti-CD3, anti-CD4, low-dose total body irradiation (3 to 6 Gy TBI) and fully mismatched or haploidentical donor bone marrow cells. Stable multilineage chimerism and specific T-cell nonresponsiveness developed. Donor skin grafts were permanently accepted. These results suggest that this single day protocol has clear potential for application in both cadaveric and living-related organ transplantation.     

Ascorbate recycling in human neutrophils: induction by bacteria

Ascorbate (vitamin C) recycling occurs when extracellular ascorbate is oxidized, transported as dehydroascorbic acid, and reduced intracellularly to ascorbate. We investigated microorganism induction of ascorbate recycling in human neutrophils and in microorganisms themselves. Ascorbate recycling was determined by measuring intracellular ascorbate accumulation. Ascorbate recycling in neutrophils was induced by both Gram-positive and Gram-negative pathogenic bacteria, and the fungal pathogen Candida albicans. Induction of recycling resulted in as high as a 30-fold increase in intracellular ascorbate compared with neutrophils not exposed to microorganisms. Recycling occurred at physiologic concentrations of extracellular ascorbate within 20 min, occurred over a 100-fold range of effector/target ratios, and depended on oxidation of extracellular ascorbate to dehydroascorbic acid. Ascorbate recycling did not occur in bacteria nor in C. albicans. Ascorbate did not enter microorganisms, and dehydroascorbic acid entry was less than could be accounted for by diffusion. Because microorganism lysates reduced dehydroascorbic acid to ascorbate, ascorbate recycling was absent because of negligible entry of the substrate dehydroascorbic acid. Because ascorbate recycling occurs in human neutrophils but not in microorganisms, it may represent a eukaryotic defense mechanism against oxidants with possible clinical implications.     

Effects of ipsilateral and contralateral counterirritation on experimentally produced itch in human beings.

Reviewed the experimental study of itch and conducted an experiment to test the effects of ipsilateral and contralateral counterirritation distal to the itching wrist. Each of 18 female undergraduates served in all experimental conditions, receiving cowage as the itch stimulus and a placebo. Counterirritation consisted of a 10-sec immersion of the fingers into a 2.C water bath. Lateral differences both in response to cowage and to counterirritation were obtained. In general, counterirritation reduced itch significantly more than the control procedure during the treatment period and the 1st 3 intervals following treatment. Results suggest a central mechanism attenuating the sensation of itch. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Altered myocardial phenotype after mechanical support in human beings with advanced cardiomyopathy

BACKGROUND: Left ventricular assist devices (LVAD) provide lifesaving circulatory support to patients awaiting heart transplantation. To date, the extent to which sustained mechanical unloading alters the phenotype of pathologic myocardial hypertrophy in dilated cardiomyopathy is unknown. METHODS: We examined left ventricular size, myocyte and myocardial immunoreactivity for atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in eight patients with advanced dilated cardiomyopathy before and after LVAD support. The mean duration of congestive heart failure was 18 +/- 5 months, and LVAD support averaged 42 +/- 4 days before heart transplantation. RESULTS: Echocardiographically determined left ventricular mass decreased from 505 +/- 83 to 297 +/- 52 gm (p < 0.05) during LVAD support, whereas minimum myocyte diameter decreased from 28.1 +/- 0.9 to 21.7 +/- 0.6 microns (p < 0.01) in transmural myocardial tissue specimens. Overall left ventricular ANP immunopositivity decreased from 48% at LVAD placement to 12% at transplantation (p < 0.05), whereas BNP immunopositivity decreased from 28% to 4% after LVAD support. Moreover, a gradient of ANP and BNP immunostaining from subendocardium to epicardium observed before mechanical unloading diminished after LVAD support. Analysis of the relationship between left ventricular mass and ANP immunopositivity revealed a close and highly significant correlation between these variables. CONCLUSIONS: These studies demonstrate remarkable left ventricular plasticity even in the presence of advanced cardiomyopathy. Parallel reductions in myocardial mass and myocyte size with reductions in ventricular ANP and BNP immunostaining indicate a novel regression of the phenotype of pathologic hypertrophy within the human myocardium after LVAD support.     

Comparative effects of omeprazole on xenobiotic metabolizing enzymes in the rat and human

Omeprazole induces CYP1A in the human liver and gut, which has led to concern about possible side effects. The purpose of this study was to compare the effects of omeprazole on phase 1 and phase 2 enzymes in the rat and human. Male rats were treated with intraperitoneal (40 or 80 mg/kg) or oral omeprazole (40 mg/kg) for 5 or 14 days, respectively. The activities and amounts of CYP1A, uridine diphosphate-glucuronosyltransferase, and glutathione transferase were determined in liver and gut. Enzyme activities were also determined in duodenal biopsy specimens from six healthy human volunteers before and after treatment with omeprazole (20 mg/day) for 10 days. Treatment with intraperitoneal omeprazole (40 mg/kg; 80 mg/kg) coinduced uridine diphosphate-glucuronosyltransferase (36%; 66%), glutathione transferase (22%; 50%), and CYP1A (26%; 50%) in rat liver. In rat small intestine, comparable levels of induction were observed for uridine diphosphate-glucuronosyltransferase and glutathione transferase; CYP1A was unaffected. Oral omeprazole had similar effects. Immunoblotting showed corresponding changes in the amounts of these enzymes. Omeprazole increased the activities of CYP1A (19% to 167%; p = 0.014) and uridine diphosphate-glucuronosyltransferase (11% to 68%; p = 0.04) in the duodenal biopsy specimens of all six human volunteers; glutathione transferase was unaffected. Thus, omeprazole coinduced multiple xenobiotic metabolizing enzymes in the rat and human. The pattern of induction differed in the rat and human, consistent with known differences in genetic regulatory elements in the two species.     

Differential induction of apoptosis by Fas-Fas ligand interactions in human monocytes and macrophages

PURPOSE: To evaluate the differences in accommodative function between subjects with emmetropia and those with late-onset myopia (LOM). METHODS: This study suggests a modified model of static accommodation, in which an accommodative sensory gain as a linear operator is added to simulate the sensory part of the system. Results derived from the model show that the sensory part not only affects the slope of the accommodative response function but also increases the system's effective threshold (ET) to the blur signal. This method expands the utility of using the control model to evaluate accommodation behavior. Thirteen emmetropic and 10 LOM subjects participated in this study. The subject's accommodative responses to one-, two-, three-, and four-diopter stimuli were measured by the Canon R-1 optometer, and the differences in dark focus, the slope of the accommodative response function, and the ET were compared between the emmetropic and the LOM subjects. RESULTS: The results show that although the dark-focus values and the slopes of the accommodative response function are not significantly different in emmetropia and LOM, the ETs are significantly different. CONCLUSIONS: The higher ET found among subjects with LOM suggests that either the blur (or the error) signal is degraded significantly in the sensory part of the system, the dead space as an internal threshold of the system is high, or both factors are important. On the basis of further analysis of the data, we speculate that the sensory system in LOM subjects was less sensitive to blur than that of the emmetropic subjects.     

Extrapolation of in vitro enzyme induction data to humans in vivo

Enzyme induction generally increases the rate and extent of xenobiotic metabolism in vitro, but physiological constraints can dampen these effects in vivo. Biotransformation kinetics determined in hepatocytes in vitro can be extrapolated to whole animals based on the hepatocellularity of the liver, since the initial velocity of an enzyme-catalyzed reaction is directly proportional to the total enzyme present in the cell. The biotransformation kinetics of various xenobiotics determined with isolated hepatocytes in vitro have been shown to accurately predict pharmacokinetics in whole animals. Analysis of the kinetic data, using physiologically based pharmacokinetics, allows extrapolation of xenobiotic biotransformation across dose routes and species in a biologically realistic context. Several fold variations were observed in the bioactivation of the hepatotoxicant furan by isolated human hepatocytes, due to induction of cytochrome P450 2E1. Extrapolation of these data to humans in vivo showed that furan bioactivation was limited by hepatic blood flow delivery of the substrate. One important consequence of hepatic blood flow limitation is that the amount of metabolite formed in the liver is unaffected by increases in Vmax due to enzyme induction. Therefore, interindividual variations in cytochrome P450 2E1 among human populations would not affect the bioactivation of many rapidly metabolized hazardous chemical air pollutants. The hepatic blood flow limitation of biotransformation is also observed after oral bolus dosing of rapidly metabolized compounds. More slowly metabolized xenobiotics, such as therapeutic agents, are only partially limited by hepatic blood flow and other processes.     

In vivo induction of tyrosylprotein sulfotransferase by ethanol: role of increased enzyme synthesis

Tyrosine sulfation is a posttranslational modification involved in the synthesis, secretion, and biological activity of proteins and peptides. Our previous studies have demonstrated that the enzyme activity was induced by ethanol. In the present work, the induction was studied in detail. Initial experiments were conducted to examine the time course of tyrosylprotein sulfotransferase (TPST) induction in rats pair-fed liquid diets containing either ethanol or carbohydrate substitute (controls). Marked elevation of TPST activity (3-fold) was measured on day 10 in the liver and gastric mucosa of ethanol-fed rats. Ethanol-mediated enhancement was also noticed by Western-blot analysis with anti-TPST antibody in both the liver and gastric mucosa on days 5 and 10. We then determined the steady-state TPST protein turnover in ethanol-fed and control animals that were given 35S-methionine after 10 days of pair-feeding with liquid diet. The rates of TPST synthesis assessed by measuring initial rates of incorporation of 35S-methionine into TPST was increased in the liver and gastric mucosa of animals fed with ethanol. Monophasic exponential decay curves showed that TPST protein half-lives for liver (control: 34 hr, ethanol: 32 hr) and gastric mucosa (control: 52 hr, ethanol: 48 hr) did not differ between control and ethanol groups. Our overall results indicate that the in vivo induction of TPST by ethanol involves increased enzyme synthesis rather than decreased enzyme degradation.     

The intermolecular cross-links in uterine collagens of guinea pig, pig, cow, and human beings

The intermolecular cross-links have been studied in the uterine insoluble collagen of guinea pig, pig, cow, and human beings with a single given procedure. After NaB3H4 reduction, there are three intermolecular cross-links; namely, dihydroxylysinonorleucine, hydroxylysinonorleucine, and histidinohydroxymerodesmosine. In human uterine collagen samples these reduced cross-links are present in equal amounts. The reduced intermolecular collagen cross-links of uterine leiomyoma are very similar to those of the normal uterine tissue. Dihydroxylysinonorleucine is the principal reduced cross-link in uterine collagen of guinea pig, pig, and cow. Alkaline hydrolysis reveals that dehydrodihydroxylysinonorleucine and dehydrohydroxylysinonorleucine occur in vivo as glycosylated derivatives.