Concentration-dependent inversion of antioxidant and prooxidant effects of β-carotene in tissuesin vivo

Low doses (below 20 mg/kg) of oral β-carotene inhibit, while high doses (above 100 mg/kg) activate ascorbate-dependent LPO in rat liver and myocardial cells. Administration of β-carotene in a dose of 20 mg/kg decreased by 34% infarction zone in coronary occlusion, while the dose of 100 mg/kg was ineffective. Anin vivo concentration-dependent inversion of β-carotene from antioxidant to prooxidant in tissues is hypothesized. Pharmacological efficacy of β-carotene is determined by its antioxidant effect, while high doses provoke the prooxidant effect and can lead to negative consequences. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 9, pp. 314–316, September, 1999     

Antioxidant and immunomodulatory effects of a α-glucan from fruit body of maitake (Grifola frondosa)

The antioxidant and immunomodulatory effect of an α-glucan (designated here as MT-α-glucan) from fruit body of Maitake mushroom (Grifola frondosa) on D-galactose (D-gal)-induced senescent mice model was evaluated. Results showed that MT-α-glucan could ameliorate age-related alternations in both motor and memory activities of senescent mice. Treatment with MT-α-glucan (450 or 150 mg kg^?1) significantly increased the body weight, hepatic superoxide dismutase and glutathione peroxidase activity, reduced glutathione content, the proliferative response and interleukine-2 (IL-2) production of splenocytes induced by ConA. Treatment with MT-α-glucan significantly decreased hepatic malondialdehyde content, the levels of macrophage proliferative response and IL-1 and NO production. These data suggest that MT-α-glucan has antioxidative and immunomodulatory effects on D-gal-induced senescent mice.     

Neuroprotective effects of cyanidin 3-O-glucopyranoside on amyloid beta (25–35) oligomer-induced toxicity

Recent studies suggest that the oligomers of short amyloid beta (Aβ) peptides such as Aβ_25–35 as well as full-length Aβ peptides (i.e. Aβ_1–40 and Aβ_1–42 peptides) are responsible for synaptic dysfunction and/or neuronal loss in Alzheimer's disease (AD). Among antioxidant phytochemicals derived from fruit and vegetables, cyanidin 3-O-glucoside (Cy-3G) has recently gained attention for its neuroprotective properties. In this in vitro study, we demonstrated that Cy-3G can inhibit Aβ_25–35 spontaneous aggregation into oligomers and their neurotoxicity in human neuronal SH-SY5Y cells. In particular, the pre- and co-treatment of SH-SY5Y cells with Cy-3G reduced the neuronal death, in terms of apoptosis and necrosis, elicited by Aβ_25–35 oligomers. Cy-3G also shows the interesting ability to prevent the early events leading to neuronal death such as the Aβ_25–35 oligomer binding to plasma membrane and the subsequent membrane integrity loss. Taken together, these findings suggest that Cy-3G may be considered a phytochemical with neuroprotective properties useful in finding potential drug or food supplements for the therapy of AD.     

Cloning and characterization of the abfB gene coding for the major α-l-arabinofuranosidase (ABF B) of Aspergillus niger

Based on amino-acid sequence data from Aspergillus niger -l-arabinofuranosidase B (ABF B), and cyanogen bromide fragments derived thereof, deoxyoligonucleotide mixtures were designed to the employed as primers in a polymerase chain reaction (PCR) on A. niger genomic DNA. This resulted in amplification of three related PCR products. The abfB gene encoding ABF B was isolated from a genomic library using such an amplification product as a probe. A 5.1-kb BamHI fragment was subcloned to result in plasmid pIM991. Upon introduction by co-transformation into both A. niger and A. nidulans uridine auxotrophic strains, pIM991 was shown to contain the functional gene since prototrophic transformants overproduced ABF B upon growth on the inducing carbon source sugar beet pulp. A plate assay was developed enabling quick selection of ABF B-overproducing transformants. The sequence of a 4122-bp long BamHI/SstI fragment was determined. The abfB gene does not contain introns and codes for a protein of 499 amino acids. The mature ABF B, 481 amino acids in length, has a deduced molecular weight of 50.7 kDa. A. niger abfB is the first eukaryotic gene encoding an ABF to be characterized.     

Characterization of a novel α-amylase from Lipomyces kononenkoae and expression of its gene (LKA1) in Saccharomyces cerevisiae

A highly active -amylase (76 250 Da) secreted by the raw starch-degrading yeast Lipomyces kononenkoae strain IGC4052B was purified and characterized. Using high performance liquid chromatography (HPLC), end-product analysis indicated that the L. kononenkoae -amylase acted by endo-hydrolysis on glucose polymers containing -1,4 and -1,6 bonds, producing mainly maltose, maltotriose and maltotetraose. The following NH₂-terminal amino acids were determined for the purified enzyme: Asp-Cys-Thr-Thr-Val-Thr-Val-Leu-Ser-Ser-Pro-Glu-Ser-Val-Thr-Gly. The L. kononenkoae -amylase-encoding gene (LKA1), previously cloned as a cDNA fragment, was expressed in Saccharomyces cerevisiae under the control of the PGK1 promoter. The native signal sequence efficiently directed the secretion of the glycosylated protein in S. cerevisiae. De-glycosylation of the enzyme indicated that post-translational glycosylation is different in S. cerevisiae from that in L. kononenkoae. Zymogram analysis indicated that glycosylation of the protein in S. cerevisiae had a negative effect on enzyme activity. Southern-blot analysis revealed that there is only a single LKA1 gene present in the genome of L. kononenkoae.     

Adult mortality and blood feeding behavioral effects of α-amyrin acetate, a novel bioactive compound on in vivo exposed females of Anopheles stephensi Liston (Diptera: Culicidae)

The effect of α-amyrin acetate on mortality and blood feeding behavior in females of Anopheles stephensi was assessed by in vivo exposure on treated guinea pig skin. In vivo exposure to α-amyrin acetate caused mosquito knock down in the form of rapidly and normally reversible paralysis and the subsequent record at the end of a 24 h, revealed mortality rates of females increased from 0.0% (Control) to 76.9% at 1.6% α-amyrin acetate, the highest concentration which implies the contact toxicity of the α-amyrin acetate received through the sensitive parts of test species. The mean probing time responses significantly increased (P?相似文献   

On the relations between affordance and representation of the agent’s effector

The present study aimed to determine whether the representation of object affordances requires specification of the effector potentially interacting with the object: specifically, in this study, vision of the interacting hand. In Experiment 1 we used an apparatus by which a fruit to be reached and grasped was identified by word reading, whereas another (interfering) fruit was visually perceived at the same location as the target. The apparatus allowed visual presentation of the agent’s interacting hand or prevented it. When visually presented, the hand was perceived as still at the start position even when it moved to grasp the fruit. An interference effect on the grasp congruent with the distractor size was observed only when the hand was visible. In Experiment 2, interference was observed also when a hand different from the agent’s own was visually presented. In both Experiments 1 and 2 the visible fruit interfered with the arm’s reach, but the effect was independent of its size and less dependent on the visually-presented hand. A control experiment (Experiment 3) enabled comparison of the interference of visual stimuli on targets identified by word reading (Experiments 1 and 2) with that of objects identified by word reading on visually-presented targets (Experiment 3). The interference induced by visual stimuli was stronger than the interference induced by objects identified by words (i.e. affordances evoked by visual stimuli were stronger than affordances evoked by semantics). Taken together, the results of the present study suggest that the specification of the agent’s effector is necessary for the elicitation of affordances. However, the elicitation of these affordances was observed for interactions between object and hand (grasp), rather than for interactions between object and arm (reach). Finally, our data confirm the influence of semantics on the control of arm movements, though less strong than that due to visual input.     

Identification and functional characterization of two novel mutations in the α-helical loop (residues 484-503) of CYBB/gp91(phox) resulting in the rare X91(+) variant of chronic granulomatous disease

Chronic granulomatous disease (CGD) is mainly caused by mutations in X-linked CYBB that encodes gp91. We have identified two novel mutations in CYBB resulting in the rare X91(+)-CGD variant, c.1500T>G (p.Asp500Glu) in two male siblings and c.1463C>A (p.Ala488Asp) in an unrelated male. Zymosan and/or PMA (Phorbol 12-myristate 13-acetate)-induced recruitment of p47(phox) and p67(phox) to the membrane fraction was normal for both mutants. Cell-free assays using recombinant wild-type and the mutant proteins revealed that these mutants were not activated by NADPH (nicotinamide adenine dinucleotide phosphate). Interestingly, the Ala488Asp mutant was activated by NADPH in the presence of glutathione. These data suggest that the mutations prevented NADPH from binding to gp91(phox) and the requirement of a negative charge at residue 500 in gp91(phox) for NADPH oxidase assembly, in contrast to a previously described Asp500Gly change. These mutations and the effect of glutathione provide a unique insight into disease pathogenesis and potential therapy in variant X91(+)-CGD.     

Synthesis and characterization of poly(antioxidant β-amino esters) for controlled release of polyphenolic antioxidants

Attenuation of cellular oxidative stress, which plays a central role in biomaterial-induced inflammation, provides an exciting opportunity to control the host tissue response to biomaterials. In the case of biodegradable polymers, biomaterial-induced inflammation is often a result of local accumulation of polymer degradation products, hence there is a need for new biomaterials that can inhibit this response. Antioxidant polymers, which have antioxidants incorporated into the polymer backbone, are a class of biomaterials that, upon degradation, release active antioxidants, which can scavenge free radicals and attenuate oxidative stress, resulting in improved material biocompatibility. In this work, we have synthesized poly(antioxidant β-amino ester) (PAβAE) biodegradable hydrogels of two polyphenolic antioxidants, quercetin and curcumin. The degradation characteristics of PAβAE hydrogels and the antioxidant activity of PAβAE degradation products were studied. Treatment of endothelial cells with PAβAE degradation products protected cells from hydrogen-peroxide-induced oxidative stress.     

Expression and Localization of α-amylase in the Submandibular and Sublingual Glands of Mice

In the major salivary glands of mice, acinar cells in the parotid gland (PG) are known to be the main site for the production of the digestive enzyme α-amylase, whereas α-amylase production in the submandibular gland (SMG) and sublingual gland (SLG), as well as the cell types responsible for α-amylase production, has been less firmly established. To clarify this issue, we examined the expression and localization of both the mRNA and protein of α-amylase in the major salivary glands of male and female mice by quantitative and histochemical methods. α-amylase mRNA levels were higher in the order of PG, SMG, and SLG. No sexual difference was observed in α-amylase mRNA levels in the PG and SLG, whereas α-amylase mRNA levels in the female SMG were approximately 30% those in the male SMG. Using in situ hybridization and immunohistochemistry, signals for α-amylase mRNA and protein were found to be strongly positive in acinar cells of the PG, serous demilune cells of the SLG, and granular convoluted tubule (GCT) cells of the male SMG, weakly positive in seromucous acinar cells of the male and female SMG, and negative in mucous acinar cells of the SLG. These results clarified that α-amylase is produced mainly by GCT cells and partly by acinar cells in the SMG, whereas it is produced exclusively by serous demilune cells in the SLG of mice.     

Suppressive effects of E3330, a novel quinone derivative,on tumor necrosis factor-α generation from monocytes and macrophages

E3330 {(2E)-3-[5-(2,3-dimethoxy-6-methyl-1,4-benzoquinoyl)]-2-nonly-2-propenoic acid}, a novel synthesized hepatoprotective compound, has suppressive effects on tumor necrosis factor- (TNF-) generation from monocytes/macrophagesin vitro. E3330 (1–100 M) reduced lipopolysaccharide (LPS, 10 mg/ml or 1g/ml)-induced TNF- generation from rat resident andPropionibacterium acnes (P. acnes)-elicited peritoneal macrophages, rat and human monocytes, rat Kupffer cells, and splenic mononuclear cells in a concentration-dependent manner. E3330 also (1–100 M) suppressed TNF- generation stimulated with egg-albumin immune complex in ratP. acnes-elicited peritoneal macrophages. Northern blot analysis showed that LPS-induced expression of TNF- messenger RNA (mRNA) in human blood monocytes was suppressed by E3330. These findings indicate that E3330 has a suppressive effect on TNF- generation from monocytes/macrophages, regardless of origin or species, and this effect is based in part on the suppression of TNF- mRNA expression.     

Agonistic autoantibodies to the α(1) -adrenergic receptor and the β(2) -adrenergic receptor in Alzheimer's and vascular dementia

Although primary causes of Alzheimer's and vascular dementia are unknown, the importance of preceding vascular lesions is widely accepted. Furthermore, there is strong evidence for the involvement of autoimmune mechanisms. Here, we report the presence of agonistic autoantibodies directed at adrenergic receptors in the circulation of patients with mild to moderate Alzheimer's and vascular dementia. In 59% of these patients, agonistic autoantibodies against the α(1) -adrenergic receptor and the β(2) -adrenergic receptor were identified. The majority of positive patients (66%) contained both types of autoantibodies in combination. In a control group of patients with neurological impairments others than Alzheimer's and vascular dementia, only 17% were found to harbour these autoantibodies. The autoantibodies to the α(1) -adrenergic receptor interacted preferably with the extracellular loop1 of the receptor. They were further studied in IgG preparations from the column regenerate of a patient who underwent immunoadsorption. The α(1) -adrenergic receptor autoantibodies specifically bound to the extracellular loop1 peptide of the receptor with an apparent EC(50) value of 30 nm. They mobilized intracellular calcium in a clonal cell line expressing the human form of the α(1) -adrenergic receptor. Our data support the notion that autoimmune mechanisms play a significant role in the pathogenesis of Alzheimer's and vascular dementia. We suggest that agonistic autoantibodies to the α(1) -adrenergic and the β(2) -adrenergic receptor may contribute to vascular lesions and increased plaque formation.     

Activation of α1 and α2 noradrenergic receptors exert opposing effects on excitability of main olfactory bulb granule cells

The mammalian main olfactory bulb (MOB) receives a dense noradrenergic innervation from the pontine nucleus locus coeruleus that is important for neonatal odor preference learning and odor processing in mature animals. Modulation of GABAergic granule cells (GCs) is thought to play a key role in the net functional impact of norepinephrine (NE) release in the MOB, yet there are few direct studies of the influence of NE on these cells. In the present study we investigated noradrenergic modulation of GC excitability using electrophysiological approaches in rat MOB slices. A moderate concentration of NE (10 μM) and the α1 receptor agonist phenylephrine (10 μM) depolarized and increased spontaneous or current injection-evoked spiking in GCs. By contrast, low NE concentrations (0.1–1.0 μM) or the α2 receptor agonist clonidine (Clon, 10 μM) hyperpolarized and decreased the discharge of GCs. The effects of NE (10 μM) were blocked by antagonism of α1 and α2 receptors. Inhibitory effects of low NE concentrations were blocked or converted to excitatory responses by α2 receptor blockade, whereas excitatory effects of the moderate NE concentration were converted to inhibitory responses after α1 receptor blockade. NE (10 μM) and phenylephrine elicited inward currents that reversed near the potassium equilibrium potential. The effects of NE and phenylephrine were associated with increased membrane input resistance. Clonidine elicited an outward current associated with decreased membrane input resistance that reversed near the potassium equilibrium potential. These results indicate that α1 and α2 receptor activation exert opposing effects on GC excitability. Low concentrations of NE acting via α2 receptors suppress GC excitability, while higher concentrations of NE acting at α1 receptors increase GC excitability. These findings are consistent with recent findings that α1 and α2 receptor activation increase and decrease, respectively, GABAergic inhibition of mitral cells. The differential affinities of α1 and α2 noradrenergic receptor subtypes may allow for differential modulation of GABA release and olfactory processing as a function of the level of NE release, which in turn, is regulated by behavioral state.     

Immunomodulation by α(1)-proteinase inhibitor: lack of chemotactic effects of recombinant human α(1)-proteinase inhibitor from yeast on human peripheral blood granulocytes

Introduction: Recombinant α(1)-proteinase inhibitor, clinically developed for inhalative augmentation therapy in patients with α(1)-proteinase inhibitor deficiency or cystic fibrosis, may directly contribute to leukocyte accumulation as it may function as a chemoattractant. The migratory effects of yeast-derived human recombinant α(1)-proteinase inhibitor on human peripheral blood neutrophils and eosinophils were therefore tested in vitro. Materials and Methods: Human peripheral blood leukocytes were prepared from forearm venous blood and tested for migration toward various preparations of yeast-derived recombinant α(1)-proteinase inhibitor in modified Boyden-chamber micropore filter assays. Results: No direct effects of yeast-derived recombinant human α(1)-proteinase inhibitor on in vitro migration of isolated neutrophils or eosinophils were seen. Conclusions: The lack of direct chemotactic effects of recombinant human α(1)-proteinase inhibitor despite anti-inflammatory effects in other biological activities of leukocytes may contribute to the preserved antibacterial defense mechanisms observed in patients under experimental augmentation therapy with inhaled α(1)-proteinase inhibitor.     

Effect of strontium and gelatin on the reactivity of α-tricalcium phosphate

The hydrolysis reaction of α-tricalcium phosphate (α-TCP) is of great interest because of its widespread use in the preparation of biomaterials for hard tissue repair. The aim of this study was to investigate how this reaction is influenced by the presence of a bioactive ion, Sr²⁺, and of a biopolymer, gelatin, which were previously reported to affect the setting reaction of α-TCP-based cements. Hydrolysis experiments were carried out at different Sr²⁺ concentrations (0, 5, 10, 20 at.%) in solutions at different gelatin concentrations (0, 0.1, 0.5, 1.0 wt.%). The results indicate that Sr²⁺ delays the conversion of α-TCP into calcium-deficient hydroxyapatite (CDHA). The structural and morphological modifications of CDHA obtained from solutions at increasing Sr²⁺ concentrations indicate that during hydrolysis strontium enters the structure of CDHA, where it partially substitutes for calcium. On the contrary, α-TCP hydrolysis rate increases on increasing gelatin concentration. Gelatin promotes conversion of α-TCP into octacalcium phosphate, and strongly interacts with the nucleating and growing crystals.