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At least 793 records · Page 44Linked to original sources
PubMed1992

Stimulation of human peripheral blood mononuclear cells with anti-CD3 monoclonal antibody vs IL2: disparate effects on T cell-dependent B cell differentiation despite similar effects on generation of unrestricted cytolytic activity.

Despite their each inducing MHC-unrestricted cytolytic activity in overnight PBMC cultures mediated predominantly by CD56+ non-T cells, anti-CD3 mAb and rIL2 induce diametrically opposite effects on subsequent polyclonal T cell-dependent B cell differentiation. When added to fresh autologous PBMC, irradiated anti-CD3-stimulated PBMC inhibit generation of Ig-secreting cells (IgSC) in the secondary cultures, whereas irradiated rIL2-stimulated PBMC enhance IgSC generation. Neither carryover of the respective stimuli nor quantitative differences in levels of cytolytic activity against Daudi cells, autologous PBMC, or autologous activated B cells can explain the dichotomous anti-CD3- vs rIL2-induced effects on B cell differentiation. For both anti-CD3- and rIL2-induced effects on B cell differentiation, CD56- cells, including CD4+ and CD8+ cells, play a more dominant role than they do in generation of MHC-unrestricted cytolytic activity. In addition, although rIL2-induced enhancement of IgSC generation is insensitive to monocyte depletion by plastic adherence or by treatment with leucine methyl ester, anti-CD3-induced inhibition of IgSC generation is highly sensitive to monocyte depletion, indicating that, at least for anti-CD3-induced inhibition, multiple cell populations are required to generate the functional effect. Taken together, these results indicate that differences in the means of generating in vitro tumoricidal activity may have profound ramifications for non-cytotoxic immune parameters, such as B cell differentiation. Not only might this be an important issue to address in adoptive immunotherapy protocols for cancer patients but also adoptive immunotherapy might be applicable to certain autoimmune disorders if the ability to inhibit B cell differentiation could be channeled against the pathogenic antibody-producing B cells.

Antibodies, Monoclonal↗
PubMed1994

Generation of SO3.- and OH radicals in SO3(2-) reactions with inorganic environmental pollutants and its implications to SO3(2-) toxicity.

Electron spin resonance (ESR) spin trapping and high performance liquid chromatography (HPLC) with electron chemical detection were utilized to investigate the generation of free radicals in reactions of sulfite (SO3(2-)) with inorganic environmental pollutants. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Incubation of SO3(2-) with nitrite (NO2-) generated sulfur trioxide anion radical (SO3.-), whose yield approached saturation levels in approximately four minutes. Fe2+ promoted SO3.- formation. Molecular oxygen was required for radical generation. This was demonstrated by experiments carried out in an argon environment as well as by oxygen consumption measurements. Transition metal ions, CrO4(2-), VO2+, Fe3+, Mn2+, Ni2+, and Fe2+ enhanced SO3.- generation from SO3(2-) either through direct SO3(2-) oxidation by metal ions or by metal ions-catalyzed SO3(2-) oxidation by molecular oxygen. Incubation of SO3(2-) with H2O2 generated both SO3.- and .OH radicals as verified by spin trapping competition measurements using ethanol and formate as .OH radical scavengers. HPLC measurements showed that .OH radicals generated by reaction of SO3(2-) with H2O2 caused 2'-deoxyguanine hydroxylation to generate 8-hydroxy-2'-deoxyguanine, a DNA damage marker. The implications of SO3.- and .OH radical formation in relation to SO3(2-) toxicity are discussed.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1994

One-electron reduction of vanadate by ascorbate and related free radical generation at physiological pH.

The one-electron reduction of vanadate (vanadium(V)) by ascorbate and related free radical generation at physiological pH was investigated by ESR and ESR spin trapping. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Incubation of vanadium(V) with ascorbate generated significant amounts of vanadium(IV) in phosphate buffer (pH 7.4) but not in sodium cacodylate buffer (pH 7.4) nor in water. The vanadium(IV) yield increased with increasing ascorbate concentration, reaching a maximum at a vanadium(V): ascorbate ratio of 2:1. Addition of formate to the incubation mixture containing vanadium(V), ascorbate, and phosphate generated carboxylate radical (.COO-), indicating the formation of reactive species in the vanadium(V) reduction mechanism. In the presence of H2O2 a mixture of vanadium(V), ascorbate, and phosphate buffer generated hydroxyl radical (.OH) via a Fenton-like reaction (vanadium(IV)+H2O2-->vanadium(V)+.OH+OH-). The .OH yield was favored at relatively low ascorbate concentrations. Omission of phosphate sharply reduced the .OH yield. The vanadium(IV) generated by ascorbate reduction of vanadium(V) in the presence of phosphate was also capable of generating lipid hydroperoxide-derived free radicals from cumene hydroperoxide, a model lipid hydroperoxide. Because of the ubiquitous presence of ascorbate in cellular system at relatively high concentrations, one-electron reduction of vanadium(V) by ascorbate together with phosphate may represent an important vanadium(V) reduction pathway in vivo. The resulting reactive species generated by vanadium(IV) from H2O2 and lipid hydroperoxide via a Fenton-like reaction may play a significant role in the mechanism of vanadium(V)-induced cellular injury.

Ascorbic Acid↗
PubMed1993

Avidin attachment to biotinylated human neutrophils induces generation of superoxide anion.

The influence of biotinylation and subsequent attachment of avidin on generation of superoxide anion by human neutrophils was studied. Biotinylation of human neutrophils with succinimide ester of biotin does not reduce superoxide generation in response to activation with phorbol myristate acetate (PMA) and formyl peptide (FMLP). Addition of avidin to biotinylated, but not native, leukocytes induces generation of superoxide anion. The kinetics and level of superoxide generation by biotinylated neutrophils in response to addition of avidin were quite similar to those in response to activation with FMLP. The avidin sugar moiety and charge were not involved in superoxide generation, since streptavidin was also active. Both avidin- and PMA-induced superoxide generation were independent of the extracellular calcium, while FMLP-induced superoxide generation was dependent on the presence of calcium in solution. Therefore, interaction of avidin with biotinylated components of the neutrophil membrane alters functional activity of this cell and might induce 'activation-like' reaction of leukocytes.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed1992

Reproductive and neurobehavioural effects in three-generation toxicity study of piperonyl butoxide administered to mice.

Piperonyl butoxide (PB) was administered continuously to mice from 5 weeks of age in the F0 generation to weaning of the F2 generation. PB was administered in the diet at levels of 0 (control), 0.1, 0.2, 0.4 and 0.8%. Selected reproductive, developmental and behavioural parameters were measured. Litter size and litter weight were reduced in higher-dosed groups, and the body weight of the pups in the lactation period was reduced in dosed pups in each generation. The survival index at postnatal day 21 of the group receiving 0.8% PB was reduced in each generation. The developmental and behavioural parameters in the lactation period were little different from those of the controls, apart from olfactory orientation in the F1 generation. However, in the F2 generation mice, surface righting, cliff avoidance and olfactory orientation were adversely affected in treatment groups. The results suggest that PB had adverse effects on reproductive, developmental and behavioural parameters of mice, with increasing effects in subsequent generations of offspring.

Administration, Oral↗
PubMed1990

Increased multiplicity of lung adenomas in five generations of mice treated with benz(a)pyrene when pregnant.

The effect of benz(a)pyrene (BP) given to female mice of A strain on the 18 and 19th days of pregnancy was studied in 5 consecutive generations. As expected there was a high incidence of lung tumours (TBA%) in the F1-generation of mice treated with BP (53.9 vs. 15.4% in control in females and 77.6 vs. 8.0% in control in males). The percentage of TBA was not increased (with one exception) in both males and females of F2-F5 generations which were not directly exposed to carcinogen. Tumor multiplicity increase occurred not only in the F1 generation of BP-treated mice but in both males and females of F2-F5 generations of mice which were not in direct contact with the carcinogen. This increase was statistically significant. There was a slight negative trend within F2-F5 generation of BP-treated mice which however was not significant. Thus the transgenerational carcinogenic effect manifested in a greater tumour multiplicity persisted for four unexposed generations.

Adenocarcinoma↗
PubMed1993

Three generation toxicity study of butylated hydroxytoluene administered to mice.

Butylated hydroxytoluene (BHT) was administered to mice, from 5 weeks of age of the F0 generation to the weaning of the F2 generation, in the diet at levels of 0 (control), 0.015, 0.045, 0.135, and 0.405%, and some reproductive and neurobehavioural parameters were measured. There was no consistent significant effect on number of litters, litter size, and litter weight at birth for each generation. The body weight of the pups of the 0.015% BHT group was increased at birth and during the lactation period for each generation. In the F2 generation, the body weights of the pups of other treatment groups were increased during the lactation period, particularly at postnatal day (PND) 21. In the neurobehavioural parameters, a few parameters were increased in treatment groups; i.e., surface righting at PND 7 in the F1 generation, surface righting at PND 4 and negative geotaxis at PND 7 in the F2 generation. The dose levels of BHT in this study showed little adverse effect on reproductive and neurobehavioural parameters on mice.

Animals↗
PubMed1996

Platelet-dependent thrombin generation in patients with diabetes mellitus: effects of glycemic control on coagulability in diabetes.

OBJECTIVES: This study sought to assess the usefulness of platelet-dependent thrombin generation as an index of coagulability in diabetes and to determine the effect of glycemic control on coagulability in diabetes. BACKGROUND: It is important to investigate the interaction of platelets and the coagulation factors to clarify the processes of the coagulation system in detail. METHODS: Platelet-rich plasma (150 X 10(9)/liter), 0.5 ml, was prepared, and 40 mmol/liter of calcium chloride was added to initiate clotting. S-2238 was added to each sample in a microtiter plate every 10 min, and the absorbance of the released color product at 2 min was measured spectrophotometrically at a wavelength of 405 nm using a microtiter plate reader as thrombin generation. We measured the platelet-independent thrombin generation in patients with non-insulin-dependent diabetes mellitus grouped according to glycemic control. RESULTS: Platelet-dependent thrombin generation at 30 min after calcium chloride addition was significantly higher in 23 patients with poorly glycemic-controlled non-insulin-dependent diabetes mellitus without complications, such as diabetic retinopathy, nephropathy and neuropathy (hemoglobin [Hb] A1c >/= 9.0%) than in 46 healthy normal subjects (448 +/- 75 vs. 165 +/- 28 mU/min, p < 0.001). Thrombin generation in 31 well controlled diabetic patients without complications (Hb A1c < 9.0%) was intermediate (240 +/- 72 mU/min) between those of the poorly controlled group and healthy normal subjects. Platelet-poor plasma from diabetic patients increased platelet-dependent thrombin generation in normal subjects. CONCLUSIONS: Coagulability is evidently enhanced in patients with non-insulin-dependent diabetes mellitus compared with that in healthy normal subjects on the basis of assessments of the platelet-dependent thrombin generation, and good glycemic control may help to correct a hypercoagulable state in diabetic patients.

Adolescent↗
PubMedDate not supplied

Rates of H2O2 generation from peroxisomal beta-oxidation are sufficient to account for fatty acid-stimulated ethanol metabolism in perfused rat liver.

Fatty acids generate H2O2 via peroxisomal beta-oxidation and increase ethanol metabolism markedly in a system that involves catalase-H2O2. The present studies were conducted to understand why fatty acid-stimulated ethanol metabolism occurs much faster than rates of H2O2 generation reported previously in perfused rat liver. A new method was developed to measure rates of H2O2 generation based on the fact that methanol is oxidized only by catalase in rat liver. Rates of H2O2 generation were estimated from the time necessary for the steady-state level of catalase-H2O2 measured spectrophotometrically (660-640 nm) through a lobe of the liver to return to basal values following the addition of a known quantity of methanol in a closed perfusion system containing 4% bovine serum albumin. Under these conditions, basal rates of H2O2 production and rates of 4-methylpyrazole-insensitive ethanol oxidation were in a similar range (10 to 20 mumol/g/hr). Rates of H2O2 generation were increased up to 80 mumol/g/hr by addition of laurate, palmitate or oleate (1 mM); half-maximal increases in rates were observed with 0.6 mM oleate. Hexanoate, a short-chain fatty acid, did not stimulate H2O2 production or ethanol uptake. In these studies, rates of H2O2 generation compared well with rates of fatty acid-stimulated ethanol uptake measured in the presence of 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, with all fatty acids studied. It is concluded, therefore, that rates of H2O2 generation are sufficient to account for rates of fatty acid-stimulated ethanol metabolism via catalase-H2O2. In addition, these data indicate that catalase may contribute significantly to ethanol oxidation under physiological conditions in the presence of fatty acids.

Animals↗
PubMed1991

Generation of 3HOH from D-[6-3H]glucose by erythrocytes: role of pyruvate alanine interconversion.

Human and rat erythrocytes were found to generate 3HOH from D-[6(N)-3H]glucose. The rate of 3HOH production represented 7-10% of the glycolytic flux. The generation of 3HOH appeared attributable, in part at least, to the detritiation of [3-3H]pyruvate during the interconversion of the 2-keto acid and L-alanine in the reaction catalyzed by glutamate-pyruvate transaminase. Indeed, purified pig heart glutamate-pyruvate transaminase, as well as homogenates prepared from rat erythrocytes or pancreatic islets, catalyzed the generation of 3HOH from L-[3-3H]alanine. When the production of tritiated pyruvate from L-[3-3H]alanine was coupled to the conversion of the 2-keto acid to L-lactate, the production of 3HOH accounted for one-third of the reaction velocity, the latter failing to display isotopic discrimination. In these experiments, the production of 3HOH was abolished by amino-oxyacetate. Likewise, in intact rat erythrocytes, aminooxyacetate inhibited the generation of 3HOH and tritiated L-alanine from D-[6-3H]glucose (or D-[1-3H]glucose), as well as the generation of 3HOH from L-[3-3H]alanine. In pancreatic islets, however, aminooxyacetate failed to affect significantly the generation of 3HOH from D-[6-3H]glucose. These findings indicate that the generation of 3HOH from D-[6-3H]glucose is mainly attributable to an intermolecular tritium transfer in transaminase reaction, at least in cells devoid of mitochondria.

Alanine↗
PubMed1994

Chromate-mediated free radical generation from cysteine, penicillamine, hydrogen peroxide, and lipid hydroperoxides.

The Cr(VI)-mediated free radical generation from cysteine, penicillamine, hydrogen peroxide, and model lipid hydroperoxides was investigated utilizing the electron spin resonance (ESR) spin trapping technique. Incubation of Cr(VI) with cysteine (Cys) generated cysteinyl radical. Radical yield depended on the relative concentrations of Cr(VI) and Cys. The radical generation became detectable at a cysteine:Cr(VI) ratio of about 5, reached its highest level at a ratio of 30, and declined thereafter. Cr(VI) or Cys alone did not generate a detectable amount of free radicals. Similar results were obtained with penicillamine. Incubation of Cr(VI), Cys or penicillamine and H2O2 led to hydroxyl (.OH) radical generation, which was verified by quantitative competition experiments utilizing ethanol. The mechanism for .OH radical generation is considered to be a Cr(VI)-mediated Fenton-like reaction. When model lipid hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide were used in place of H2O2, hydroperoxide-derived free radicals were produced. Since thiols, such as Cys, exist in cellular systems at relatively high concentrations, Cr(VI)-mediated free radical generation in the presence of thiols may participate in the mechanisms of Cr(VI)-induced toxicity and carcinogenesis.

Chromates↗
PubMed1991

Immunocytochemical characterisation of two generations of fibers during the development of the human quadriceps muscle.

We have carried out a comprehensive study of the formation of muscle fibers in the human quadriceps in a large series of well dated human foetuses and children. Our results demonstrate that a first generation of muscle fibers forms between 8-10 weeks. These fibers all express slow twitch myosin heavy chain (MHC) in addition to embryonic and foetal MHCs, vimentin and desmin. Between 10-11 weeks, a subpopulation of these fibers express slow tonic MHC, being the first primordia of muscle spindles. Extrafusal fibers of a second generation form progressively and asynchronously around the primary fibers between 10-18 weeks, giving the muscle a very heterogeneous aspect due to different degrees of organization of their proteins. By 20 weeks, these second generation fibers become homogeneous and thereafter undergo a process of maturation and differentiation when they eliminate vimentin, embryonic and foetal MHCs to express either slow twitch or fast MHC. The differentiation of these second generation fibers into slow and fast depends upon different factors, such as motor innervation or level of thyroid hormone. Around the intrafusal first generation fibers, additional subsequent generations of fibers are also progressively formed. Some differ from the extrafusal second generation fibers by expressing slow tonic MHC, others by continuous expression of foetal MHC. The differentiation of intrafusal fibers is probably under the influence of both sensory and motor innervation.

Desmin↗
PubMed2006

Differences in brain information transmission between gifted and normal children during scientific hypothesis generation.

The purpose of the present study was to investigate differences in neural information transmission between gifted and normal children involved in scientific hypothesis generation. To investigate changes in the amount of information transmission, the children's averaged-cross mutual information (A-CMI) of EEGs was estimated during their generation of scientific hypotheses. We recorded EEG from 25 gifted and 25 age-matched normal children using 16 electrodes on each subject's scalp. To generate hypotheses, the children were asked to observe 20 "quail eggs" that gave rise to questions. After observation, they were asked to generate a scientific hypothesis--a tentative causal explanation for the questions evoked. The results of this study revealed several distinguishing brain activities between gifted and normal children during hypothesis generation. In contrast to normal children, gifted children showed increased A-CMI values between the left temporal and central, between the left temporal and parietal, and between the left central and parietal locations while generating a hypothesis. These results suggested that gifted children more efficiently distribute the cognitive resources essential to cope with hypothesis generation.

Aptitude↗
PubMed2005

Visualizing common deletion of mitochondrial DNA-augmented mitochondrial reactive oxygen species generation and apoptosis upon oxidative stress.

Common deletion (CD) 4977 bp of mitochondrial DNA (mtDNA) disrupt specifically mitochondrial complex I, IV and V on the electron transport chain (ETC) and is closely associated with wide spectrums of clinical manifestations. To quantitatively investigate how CD-induced ETC defect alters mitochondrial reactive oxygen species (mROS) generation as well as down stream apoptotic signaling, we employed an established array of human CD cytoplasmic hybrids (cybrids) harboring 0%-80% of CD. Pathological effects of CD on the mitochondria were visualized at single cell level by the application of fluorescent probes coupled with conventional and multiphoton imaging microscopy. Intriguingly, we observed CD-augmented mROS generation omitted "threshold effect". CD-augmented mROS generation was associated with depolarized mitochondrial membrane potential (DeltaPsi(m)). Upon oxidative stress, the amount of CD-augmented mROS generation was greatly enhanced to cause pathological apoptotic deterioration including opening of the mitochondrial permeability transition, cytochrome c release, phosphatidylserine externalization and DNA fragmentation. In addition, heterogeneous mitochondrial dysfunctions were found in cybrids containing 80% of CD (D cybrids), i.e., low sensitive-D (LS-D, roughly 80%) and a super sensitive-D (SS-D, 20%). As compared to LS-D, SS-D had higher resting mROS level but slightly hyperpolarized DeltaPsi(m). Upon H2O2 treatment, much faster generation of mROS was observed which induced a faster depolarization of DeltaPsi(m) and later apoptotic deterioration in SS-D. We proposed a dose-dependent, feed-forward and self-accelerating vicious cycle of mROS production might be initiated in CD-induced ETC defect without threshold effect. As CD-augmented mROS generation is obligated to cause an enhanced pathological apoptosis, precise detection of CD-augmented mROS generation and their degree of heterogeneity in single cells may serve as sensitive pathological indexes for early diagnosis, prognosis and treatment of CD-associated diseases.

Apoptosis↗
PubMed2006

Selective roles for alpha-PKC in positive signaling for O-(2) generation and calcium mobilization but not elastase release in differentiated HL60 cells.

Protein kinase C (PKC) isotypes and Ca2+ mobilization have been implicated in phagocytic cell functions such as O(-)(2) generation. Ca/DG-dependent alpha-PKC and beta-PKC have similar substrate specificities and cofactor requirements in vitro. However it is not known if these isotypes play redundant or unique roles in the intact cell. In the present study, a role for alpha-PKC in positive signaling for fMet-Leu-Phe- and PMA-activated O(-)(2) generation was probed using an siRNA strategy in HL60 cells differentiated to a neutrophilic phenotype (dHL60 cells). A selective decrease in alpha-PKC in dHL60 cells attenuated O(-)(2) generation but not degranulation, and reduced ligand-induced phosphorylation of p47phox as previously shown for beta-PKC. However alpha-PKC, unlike beta-PKC, was a positive regulator of fMet-Leu-Phe-triggered Ca2+ uptake via SOCC (Store Operated Calcium Channels). The ability of a selective SOCC inhibitor, MRS1845, to decrease fMet-Leu-Phe induced Ca2+ uptake and O(-)(2) generation confirmed that Ca2+ uptake via SOCC was required for O(-)(2) generation. These results indicate that alpha-PKC and beta-PKC are required for optimal O(-)(2) generation, but play different roles in Ca2+ signaling for phagocytic responses such as O(-)(2) generation.

Calcium↗
PubMed2005

Reactive oxygen species generation and its role in the differential cytotoxicity of the arylhydroxylamine metabolites of sulfamethoxazole and dapsone in normal human epidermal keratinocytes.

Cutaneous drug reactions (CDR) are responsible for numerous minor to life-threatening complications. Though the exact mechanism for CDR is not completely understood, evidence suggests that bioactivation of drugs to reactive oxygen or nitrogen species is an important factor in the initiation of these reactions. Several CDR-inducing drugs having an arylamine functional group, such as sulfamethoxazole (SMX) and dapsone (DDS), undergo bioactivation to reactive arylhydroxylamine metabolites. These metabolites can generate cellular oxidative stress by forming reactive oxygen species (ROS). Several studies have demonstrated a higher cytotoxicity with DDS hydroxylamine (DDS-NOH) compared to SMX hydroxylamine (SMX-NOH). To investigate the role of differential ROS generation in the higher cytotoxicity of DDS-NOH, hydroxylamine metabolites of SMX and DDS were synthesized and ROS formation by these metabolites determined. DDS-NOH and its analogues/metabolites consistently resulted in higher ROS formation as compared to SMX-NOH. However, comparison of the ROS generation and cytotoxicity of a series of arylhydroxylamine analogues of DDS did not support a simple correlation between ROS generation and cell death. Numerous ROS scavengers were found to reduce metabolite-induced ROS formation, with differences in the potency between the agents. The decrease in DDS-NOH-induced ROS generation in NHEK with ascorbic acid, N-acetylcysteine, Trolox, and melatonin was 87, 86, 44, and 16%, respectively. Similarly, the cytotoxicity and adduct formation of DDS-NOH in NHEK was reduced in the presence of ascorbic acid. In summary, these studies show that arylhydroxylamine metabolites of SMX/DDS induce ROS generation in NHEK, though such generation is not directly related to cytotoxicity.

Cells, Cultured↗
PubMed2006

Effect of Agkistroden blomhoffi (mamushi) on superoxide generation in human neutrophils.

BACKGROUND: The purpose of this study is to investigate the effect of Agkistroden blomhoffi (mamushi) aqueous extract on stimulus-induced superoxide generation in human neutrophils. METHODS: Superoxide generation was assayed by measuring the reduction of ferricytochrome C (cyt c) using a dual-beam spectrophotometer. The phosphorylation of neutrophil proteins and the translocation of cytosolic compounds to the cell membrane were detected using specific monoclonal antibodies. RESULTS: Mamushi aqueous extract markedly suppressed fMLP-induced superoxide generation in a concentration-dependent manner. fMLP-induced translocation of cytosolic compounds p47phox, p67phox and Rac to the cell membrane was suppressed in parallel to the suppression of superoxide generation. The fractions with MW below 10 kDa dose-dependently suppressed tyrosyl phosphorylation of 45.0, 77.6 and 99.5 kDa proteins in fMLP-treated human neutrophils; the inhibition of tyrosyl phosphorylation was in parallel to that of the fMLP-induced translocation of p47phox to the cell membrane and superoxide generation. CONCLUSIONS: Mamushi aqueous extract markedly suppressed fMLP-induced superoxide generation in human neutrophils and also suppressed the translocation of cytosolic compounds to the cell membrane and tyrosyl phosphorylation of proteins. The efficacious components are the fractions with MW below 10 kDa. O-phosphoserylethanolamine, a new dipeptide isolated from mamushi, also suppressed fMLP-induced superoxide generation in human neutrophils in a dose-dependent manner.

Agkistrodon↗
PubMed2005

Cortical generators of slow evoked responses elicited by spatial and nonspatial auditory working memory tasks.

OBJECTIVE: Slow evoked responses have been extensively studied using electrophysiological and neuroimaging methods, but there is no consensus regarding their generators. We investigated the generators of the P3 and positive slow wave (PSW) in the evoked responses to probes recorded during auditory working memory tasks to find out whether there is dissociation between functional networks involved in the generation of the P3 and PSW and between spatial and nonspatial auditory processing within this time window. METHODS: Whole-head magneto-(MEG) and electroencephalography (EEG); analysis of MEG data using minimum-norm current estimates. RESULTS: The associative temporal, occipito-temporal and parietal areas contributed to the generation of the slow evoked responses. The temporal source increased while the occipito-temporal source diminished activity during transition from the P3 to PSW. The occipito-temporal generator of the P3 was activated more during the spatial than nonspatial task, and the left temporal generator of the PSW tended to be more strongly activated during the nonspatial task. CONCLUSIONS: These findings indicate that partially distinct functional networks generate the P3 and PSW and provide evidence for segregation of spatial and nonspatial auditory information processing in associative areas beyond the supratemporal auditory cortex. SIGNIFICANCE: The present results support the dual-stream model for auditory information processing.

Acoustic Stimulation↗