Implication of polymorphisms in DNA repair genes with an increased risk of hepatocellular carcinoma

We explored the association between 4 XRCC1 (Arg194Trp and Arg399Gln) and XPD (Asp312Asn and Lys751Gln) polymorphisms with the development and prognosis of hepatocellular carcinoma (HCC). A total of 218 cases with HCC and 277 healthy controls were included in the study. Genotyping of the XRCC1 (Arg194Trp and Arg399Gln) and XPD (Asp312Asn and Lys751Gln) polymorphisms was performed in a 384-well plate format on the Sequenom MassARRAY platform. We found that individuals with the XRCC1 399AA genotype had a higher risk of HCC compared with the GG genotype (odds ratio, OR = 1.85, 95% confidence interval, CI = 1.03-3.23). Similarly, individuals carrying the XPD 751GG genotype showed a greatly increased risk of HCC (OR = 2.97, 95%CI = 126- 7.38). Cox regression analysis showed that individuals carrying XPD 751Gln/Gln genotypes had a 0.30-fold increased risk of death from HCC. These results suggest that polymorphisms in XRCC1 and XPD may have functional significance in HCC.

Effects of clinoptilolite and modified clinoptilolite on the growth performance, intestinal microflora, and gut parameters of broilers

The purpose of this study was to evaluate the effect of natural clinoptilolite (NCLI) and modified clinoptilolite (MCLI) on broiler performance, gut morphology, and its relation to gut circumstances. A total of two hundred forty 1-d-old male chicks were randomly assigned to 3 treatments, each of which comprised 8 pens of 10 chicks per pen. Birds in the control group were fed the basal diet, whereas those in the experimental groups were fed diets supplemented with NCLI at 2% (NCLI group) or MCLI at 2% (MCLI group) for 42 d. The results showed that compared with the control, supplementation with NCLI or MCLI had no significant (P > 0.05) effects on productive parameters from d 1 to 42. Supplementation with MCLI and NCLI was associated with greater (P < 0.05) villus height in the jejunal and ileal mucosa compared with those areas in the controls from d 1 to 42. However, supplementation with NCLI and MCLI had no significant (P > 0.05) influence on the crypt depth in the jejunal and ileal mucosa compared with those in the controls. Total viable counts of Escherichia coli were significantly (P < 0.05) decreased by MCLI and NCLI from d 1 to 21. The NCLI and MCLI significantly increased the total viable counts of Lactobacillus acidophilus from d 22 to 42. Small intestine and cecal pH values in the MCLI group were found to be lower (P < 0.05) than those in other groups. Total volatile fatty acid concentrations were significantly (P < 0.05) decreased in both experimental groups from d 22 to 42. This study showed that NCLI or MCLI, as feed additives for broilers, had a positive effect on gut parameters by acting on microbial populations of the digestive tract.

Quantum Brayton cycle with coupled systems as working substance

We explore the quantum version of the Brayton cycle with a composite system as the working substance. The actual Brayton cycle consists of two adiabatic and two isobaric processes. Two pressures can be defined in our isobaric process; one corresponds to the external magnetic field (characterized by F(x)) exerted on the system, while the other corresponds to the coupling constant between the subsystems (characterized by F(y)). As a consequence, we can define two types of quantum Brayton cycle for the composite system. We find that the subsystem experiences a quantum Brayton cycle in one quantum Brayton cycle (characterized by F(x)), whereas the subsystem's cycle is quantum Otto cycle in another Brayton cycle (characterized by F(y)). The efficiency for the composite system equals to that for the subsystem in both cases, but the work done by the total system is usually larger than the sum of the work done by the two subsystems. The other interesting finding is that for the cycle characterized by F(y), the subsystem can be a refrigerator, while the total system is a heat engine. The result in this paper can be generalized to a quantum Brayton cycle with a general coupled system as the working substance.

A bio-inspired two-layer multiple-walled carbon nanotube-polymer composite sensor array and a bio-inspired fast-adaptive readout circuit for a portable electronic nose

We report a fully integrated, portable, battery-operated electronic nose system comprising a bio-inspired two-layer multiple-walled carbon nanotube (MWNT)-polymer composite sensor array, a bio-inspired fast-adaptive readout circuit, and a microprocessor embedded with a pattern recognition algorithm. The two-layer MWNT-polymer composite sensor is simple to operate, and the membrane quality can be easily controlled. These two-layer membranes have improved sensitivity and stability. The fast-adaptive readout circuit responds to the sensor response, while tuning out the long-term constant background humidity, temperature, and odors. This portable electronic nose system successfully classified four complex alcohol samples 40 times for each sample; these samples were sake, sorghum liquor, medical liquor, and whisky.

Numb regulates meiotic spindle organisation in mouse oocytes

Numb is an adaptor protein that controls the fate of cells in different species through asymmetrical inheritance by sibling cells during division. It has been investigated extensively in mitosis, mostly in neural progenitor cells, but its function in meiosis remains unknown. The present study was designed to investigate the expression, subcellular localisation and functional roles of Numb during mouse oocyte meiotic maturation. Using real-time polymerase chain reaction and western blotting, we found that the expression of Numb increased from the germinal vesicle (GV) to MII stages. Immunofluorescent staining revealed that Numb was mainly concentrated in the GV before meiosis resumption, aggregated in the vicinity of the chromosomes after GV breakdown and then localised to the spindle poles from prometaphase I to MII. Nocodazole treatment resulted in spindle destruction and Numb diffusion into the cytoplasm. However, Numb appeared at the spindle poles again once the spindles had formed when nocodazole-treated oocytes were washed and cultured for spindle recovery. Depletion of Numb by RNA interference resulted in chromosome misalignment, spindle deformation and even doubled spindle formation. Our results suggest that Numb is critical for spindle organisation during mouse oocytes meiosis. The present study provides evidence of a new function for Numb in addition to its action as a cell fate-determining factor.

Novel function and intracellular localization of methionine adenosyltransferase 2beta splicing variants

Human methionine adenosyltransferase 2beta (MAT2beta) encodes for two major splicing variants, V1 and V2, which are differentially expressed in normal tissues. Both variants are induced in human liver cancer and positively regulate growth. The aim of this work was to identify interacting proteins of V1 and V2. His-tagged V1 and V2 were overexpressed in Rosetta pLysS cells, purified, and used in a pulldown assay to identify interacting proteins from human colon cancer cell line RKO cell lysates. The eluted lysates were subjected to Western blot and in solution proteomic analyses. HuR, an mRNA-binding protein known to stabilize the mRNA of several cyclins, was identified to interact with V1 and V2. Immunoprecipitation and Western blotting confirmed their interaction in both liver and colon cancer cells. These variant proteins are located in both nucleus and cytoplasm in liver and colon cancer cells and, when overexpressed, increased the cytoplasmic HuR content. This led to increased expression of cyclin D1 and cyclin A, known targets of HuR. When endogenous expression of V1 or V2 is reduced by small interference RNA, cytoplasmic HuR content fell and the expression of these HuR target genes also decreased. Knockdown of cyclin D1 or cyclin A blunted, whereas knockdown of HuR largely prevented, the ability of V1 or V2 overexpression to induce growth. In conclusion, MAT2beta variants reside mostly in the nucleus and regulate HuR subcellular content to affect cell proliferation.

DNA-PKcs regulates a single-stranded DNA endonuclease activity of Artemis

Human nuclease Artemis belongs to the metallo-beta-lactamase protein family. It acquires double-stranded DNA endonuclease activity in the presence of DNA-PKcs. This double-stranded DNA endonuclease activity is critical for opening DNA hairpins in V(D)J recombination and is thought to be important for processing overhangs during the nonhomologous DNA end joining (NHEJ) process. Here we show that purified human Artemis exhibits single-stranded DNA endonuclease activity. This activity is proportional to the amount of highly purified Artemis from a gel filtration column. The activity is stimulated by DNA-PKcs and modulated by purified antibodies raised against Artemis. Moreover, the divalent cation-dependence and sequence-dependence of this single-stranded endonuclease activity is the same as the double-stranded DNA endonuclease activity of Artemis:DNA-PKcs. These findings further expand the range of DNA substrates upon which Artemis and Artemis:DNA-PKcs can act. The findings are discussed in the context of NHEJ.

InsPecT: identification of posttranslationally modified peptides from tandem mass spectra

Reliable identification of posttranslational modifications is key to understanding various cellular regulatory processes. We describe a tool, InsPecT, to identify posttranslational modifications using tandem mass spectrometry data. InsPecT constructs database filters that proved to be very successful in genomics searches. Given an MS/MS spectrum S and a database D, a database filter selects a small fraction of database D that is guaranteed (with high probability) to contain a peptide that produced S. InsPecT uses peptide sequence tags as efficient filters that reduce the size of the database by a few orders of magnitude while retaining the correct peptide with very high probability. In addition to filtering, InsPecT also uses novel algorithms for scoring and validating in the presence of modifications, without explicit enumeration of all variants. InsPecT identifies modified peptides with better or equivalent accuracy than other database search tools while being 2 orders of magnitude faster than SEQUEST, and substantially faster than X!TANDEM on complex mixtures. The tool was used to identify a number of novel modifications in different data sets, including many phosphopeptides in data provided by Alliance for Cellular Signaling that were missed by other tools.

Heptad repeats regulate protein phosphatase 2a recruitment to I-kappaB kinase gamma/NF-kappaB essential modulator and are targeted by human T-lymphotropic virus type 1 tax

The switching on-and-off of I-kappaB kinase (IKK) and NF-kappaB occurs rapidly after signaling. How activated IKK becomes down-regulated is not well understood. Here we show that following tumor necrosis factor-alpha stimulation, protein phosphatase 2A (PP2A) association with IKK is increased. A heptad repeat in IKKgamma, helix 2 (HLX2), mediates PP2A recruitment. Two other heptad repeats downstream of HLX2, termed coiled-coil region 2 (CCR2) and leucine zipper (LZ), bind HLX2 and negatively regulate HLX2 interaction with PP2A. HTLV-1 transactivator Tax also binds HLX2, and this interaction is enhanced by CCR2 but reduced by LZ. In the presence of Tax, PP2A-IKKgamma binding is greatly strengthened. Interestingly, peptides spanning CCR2 and/or LZ disrupt IKKgamma-Tax and IKKgamma-PP2A interactions and potently inhibit NF-kappaB activation by Tax and tumor necrosis factor-alpha. We propose that when IKK is resting, HLX2, CCR2, and LZ form a helical bundle in which HLX2 is sequestered. The HLX2-CCR2-LZ bundle becomes unfolded by signal-induced modifications of IKKgamma or after Tax binding. In this conformation, IKK becomes activated. IKKgamma then recruits PP2A via the exposed HLX2 domain for rapid down-regulation of IKK. Tax-PP2A interaction, however, renders PP2A inactive, thus maintaining Tax-PP2A-IKK in an active state. Finally, CCR2 and LZ possibly inhibit IKK activation by stabilizing the HLX2-CCR2-LZ bundle.

Osteoclastogenic activity during mandibular distraction osteogenesis

Mandibular distraction osteogenesis is a well-developed clinical modality for the treatment of craniofacial deformities and dental arch discrepancies, in combination with orthodontic treatment. However, in our previous study, orthodontic tooth movement into the distraction gap caused severe root resorption. The present study aimed to clarify the osteoclastogenic activity of cells in the distraction gap. We hypothesized that the gene expression of osteoclastogenic- and osteoclast-supporting molecules in osteoblasts and stromal cells would increase at distraction sites during the consolidation period. An animal model experiment involving rabbits was designed for mandibular distraction osteogenesis and subjected to in situ hybridization analysis. The number of osteoclasts was larger in the distraction gap during the early consolidation period than in normal controls, due to an increase of gene expression for osteoclastogenic cytokines in osteoblasts. It was concluded that osteoclastogenic and osteoclastic activities are stimulated at distraction sites during the early consolidation period.

FLI-1 functionally interacts with PIASxalpha, a member of the PIAS E3 SUMO ligase family

FLI-1 is a transcription factor of the ETS family that is involved in several developmental processes and that becomes oncogenic when overexpressed or mutated. As the functional regulators of FLI-1 are largely unknown, we performed a yeast two-hybrid screen with FLI-1 and identified the SUMO E3 ligase PIASxalpha/ARIP3 as a novel in vitro and in vivo binding partner of FLI-1. This interaction involved the ETS domain of FLI-1 and required the integrity of the SAP domain of PIASxalpha/ARIP3. SUMO-1 and Ubc9, the ubiquitin carrier protein component in the sumoylation pathway, were also identified as interactors of FLI-1. Both PIASxalpha/ARIP3 and the closely related PIASxbeta isoform specifically enhanced sumoylation of FLI-1 at Lys(67), located in its N-terminal activation domain. PIASxalpha/ARIP3 relocalized the normally nuclear but diffusely distributed FLI-1 protein to PIASxalpha nuclear bodies and repressed FLI-1 transcriptional activation as assessed using different ETS-binding site-dependent promoters and different cell systems. PIASxalpha repressive activity was independent of sumoylation and did not result from inhibition of FLI-1 DNA-binding activity. Analysis of the properties of a series of ARIP3 mutants showed that the repressive properties of PIASxalpha/ARIP3 require its physical interaction with FLI-1, identifying PIASxalpha as a novel corepressor of FLI-1.

Tumor necrosis factor alpha-dependent drug resistance to purine and pyrimidine analogues in human colon tumor cells mediated through IKK

Development of drug resistance in cancer is one of the main challenges in chemotherapy, and many mechanisms are still unknown. In this study, we show that tumor necrosis factor alpha (TNFalpha) increases postdrug survival from 5-fluoro-2'-deoxyuridine (FdUrd) in two human colon tumor cell lines. This resulted in the development of drug-resistant cells in a TNFalpha-dependent manner. Interestingly, although the drug-resistant cells were selected using FdUrd, they are also resistant to a number of other antimetabolites in the DNA synthesis pathway in a TNFalpha-dependent manner. Only in the drug-resistant cells (p35-colo201) TNFalpha treatment resulted in G(0)-G(1) arrest but not in the parental colo201 and other cell types. Blocking TNFalpha-induced cell cycle arrest sensitized drug-resistant cells to FdUrd. TNFalpha-induced cell cycle arrest required IKK. IKK inhibition by a small molecule inhibitor or by the knockdown of IKKalpha, IKKbeta, or RelA/p65 using siRNA, but not the inhibition of JNK, MEK, p38, or caspase-8 pathways, blocked TNFalpha-induced G(0)-G(1) arrest and restored sensitivity to FdUrd of drug-resistant cells. TNFalpha reduced the transcripts and protein levels of phosphorylated retinoblastoma protein (Rb), Rb, E2F1, and Cdk4 only in drug-resistant p35-colo201 cells. This effect of TNFalpha was reversed by IKK inhibitor, suggesting that TNFalpha-induced cell cycle arrest is probably due to the reduction of Rb, E2F1, and Cdk4. Taken together, this study shows that, in vitro, TNFalpha-induced cell cycle arrest through IKK can provide a mechanism for the development of drug resistance to anti-cancer drugs, purine and pyrimidine analogues.

Sera from children with active Henoch-Schönlein purpura can enhance the production of interleukin 8 by human umbilical venous endothelial cells

OBJECTIVE

To investigate the ability of sera from children with active Henoch-Schonlein purpura (HSP) to enhance endothelial interleukin (IL) 8 production and intercellular adhesion molecule (ICAM)-1 expression.

METHODS

Nine children with active HSP and nine normal healthy children were enrolled. IL8 serum levels of patients and controls at different stages were analysed. Production of IL8 and expression of ICAM-1 by human umbilical venous endothelial cells were detected (ELISA for IL8, flow cytometry for ICAM-1) and compared under various stimuli, including sera of patients at different stages, sera of controls, and medium alone.

RESULTS

Serum levels of IL8 were increased at the acute stage. Levels of IL8 in supernatants from human umbilical venous endothelial cells (HUVEC) co-cultured with sera from children with active HSP were significantly higher than those from HUVEC without any treatment (p = 0.001), HUVEC treated with inactive sera (p = 0.004), and HUVEC treated with sera from healthy controls (p = 0.004). Sera from patients and from controls did not enhance the expression of ICAM-1 on HUVEC.

CONCLUSIONS

Some factors may be present in sera from children with active HSP that could activate endothelial cells to produce IL8. This process may account, in part, for the mechanisms of perivascular neutrophil infiltration and leucocytosis in HSP.

Berry phase in a composite system

The Berry phase in a composite system with one driven subsystem has been studied in this Letter. We choose two coupled spin-1 / 2 systems as the composite system; one of the subsystems is driven by a time-dependent magnetic field. We show how the Berry phases depend on the coupling between the two subsystems, and the relation between the Berry phases of the composite system and those of its subsystems.

Activity-dependent dynamics of coexisting brain-derived neurotrophic factor, pro-opiomelanocortin and alpha-melanophore-stimulating hormone in melanotrope cells of Xenopus laevis

Brain-derived neurotrophic factor (BDNF) is involved as an autocrine factor in the regulation of the secretory activity of the neuroendocrine pituitary melanotrope cells of Xenopus laevis. We studied the subcellular distribution of BDNF in Xenopus melanotropes using a combination of high-pressure freezing, cryosubstitution and immunoelectron microscopy. Presence of BDNF, pro-opiomelanocortin (POMC) and alpha-melanophore-stimulating hormone (alphaMSH) within melanotrope secretory granules was studied by triple-labelling immunoelectron microscopy. In addition, intracellular processing of BDNF was investigated by quantifying the number of immunogold particles in different stages of secretory granule maturation, in animals adapted to black or white background light conditions. The high-pressure freezing technique provides excellent preservation of both cellular ultrastructure and antigenicity. BDNF coexists with POMC and alphaMSH within secretory granules. BDNF-immunoreactivity increases along the secretory granule maturation axis (i.e. from electron-dense, via moderately electron-dense, to electron-lucent secretory granules). Immature, low immunoreactive, electron-dense secretory granules are assumed to contain mainly or even exclusively proBDNF. Strongly immunoreactive electron-lucent secretory granules represent the mature granule stage in which proBDNF has been processed to mature BDNF. Furthermore, in moderately electron-dense secretory granules, immunoreactivity is markedly (+79%) higher in black-adapted than in white-adapted animals, indicating that stimulation of melanotrope cell activity by the black background condition speeds up processing of BDNF from its precursor in this granule stage. It is concluded that, in the Xenopus melanotrope, BDNF biosynthesis and processing occur along the secretory granule maturation axis, together with that of POMC-derived alphaMSH, and that the environmental light condition not only controls the biosynthesis and secretion of BDNF and of POMC end-products, but also regulates the rate of their intragranular processing.

Long-term effects of fertilization on soil organic carbon changes in continuous corn of northeast China: RothC model simulations

Soil organic C (SOC) content can increase by managing land use practices in which the rates of organic C input exceed those of organic C mineralization. Understanding the changes in SOC content of Black soils (mainly Typic Halpudoll) in northeast China is necessary for sustainable using of soil resources there. We used the RothC model to estimate SOC levels of Black soils under monoculture cropping corn in a long-term fertilization trial at Gongzhuling, Jilin Province, China. The model outputs for the changes in SOC were compared with measured data in this long-term fertilization/manure trial. The sound performance of model in simulating SOC changes suggests that RothC is feasible with Black soils in the temperate climatic region of northeast China. The modeled and measured results indicated that the treatment without fertilizer/farmyard manure (FYM) addition led to a continuous decline in SOC during the study period and N and NPK fertilization were inadequate to maintain the SOC levels in the plow layer (upper 20 cm) unless FYM was added under the current conventional management associated with no above-ground crop residues returning into the soil. Soil organic carbon could follow the same path of decline if the same management practices are maintained. Model results indicate that returning above-ground crop residues to the soil from 2002 to 2022 would increase SOC by 26% for the treatment without fertilization addition, 40% for N treatment, 45% for NPK treatment, and 38% and 46% for N and NPK treatments with FYM addition, compared to the levels in the corresponding treatments in 2002. The simulation results suggest that the RothC model is a feasible tool to assess SOC trend under different management practices, and returning above-ground crop residues into the soil would lead to a remarkable increase in SOC of Black soils in the region.

Recovery of type I fiber regionalization in gastrocnemius medialis of the rat after reinnervation along original and foreign paths, with and without muscle rotation

After reinnervation following transection of the sciatic nerve, normal patterns of regional type I fiber distribution are known to return in rat hindlimb muscles. Here we investigate how this recovery is influenced by experimental conditions. In an initial operation, the nerve of gastrocnemius medialis (GM) of adult rats was cut close to the muscle and reinserted either (i) close to the original nerve entry, or (ii) at a more medial 'foreign' site. In other groups of animals, these nerve operations were combined with a rotation of the GM muscle around its longitudinal axis, trying to ascertain whether the position of the muscle within the limb was of importance for the reinnervation processes. In a control group the muscle was rotated but innervation remained intact. After 21 weeks, the GM muscles were removed from both hindlimbs. Cross-sections were cut at seven different levels along each muscle, and 'slow' type I fibers were identified after staining for myofibrillar ATPase. The topographical positions were mapped out for all type I fibers. In all reinnervated muscles, an extensive type I fiber grouping was seen, indicating a widespread respecification of muscle fiber properties by ingrowing 'slow' axons. Normal topographical directions of type I fiber regionalization were about equally well restored in groups with the nerve inserted at the original or at the foreign site. In rotated muscles, the direction of type I fiber regionalization was significantly less rotated than the muscle as a whole. The results suggest that ingrowing 'slow' motor axons are guided toward their normal 'slow' regions by clues which are largely independent of the i.m. path of regeneration (original vs. foreign nerve entry site) but partly dependent on the position of the target muscle within the limb (rotated vs. non-rotated cases).

Fibre type regionalisation in lower hindlimb muscles of rabbit, rat and mouse: a comparative study

The topographical distribution of different fibre types in muscles of the lower hindlimb in rabbits and mice was quantitatively determined. The results were compared to those previously obtained, using the same new quantification methods, in homologous muscles of the rat. Type I fibres ('slow') were identified using myofibrillar ATPase histochemistry and mapped out at the mid proximo-distal level for 11 'fast' muscles in the rabbit and 7 'fast' muscles in the mouse. For the slow soleus muscle the procedure was undertaken for the type II fibres. Furthermore, for 5 of the 'fast' muscles from each animal species (extensor digitorum longus; flexor digitorum and hallucis longus; gastrocnemius medialis; peroneus longus; tibialis anterior), several more proximal and distal cross-sectional levels were also analysed. All the investigated 'fast' muscles showed a significant degree of topographical eccentricity in the midlevel distribution of type I fibres. For most muscles, the direction of this 'vector regionalisation' of type I fibres was similar between the three animal species. For homologous muscles, the degree of vector regionalisation was significantly different: mouse > rat > rabbit. The relative area of the region containing the type I fibres, inversely related to the degree of 'area regionalisation', was also significantly different: mouse < rat < rabbit. Also within each animal species, muscles with a marked degree of vector regionalisation tended to show a marked area regionalisation. Proximo-distal differences in type I fibre density were observed in all the three species of animals; also these patterns showed marked inter-species differences. The findings demonstrate the general occurrence of, and systematic relationships between, different aspects of type I fibre regionalisation. The observed interspecies differences suggest that the expression of this phenomenon is adapted to differing functional needs.

Effect of taurine on toxicity of cadmium in rats

A study was undertaken to investigate the effect of taurine on the toxicity of cadmium in male Wistar rats. The rats were divided into six groups and fed different diets with or without supplement of 5% taurine and 150-300 ppm cadmium for 2 months. It was found that the body weight of rats, the ratios of liver and kidney weight to body weight, and the level of glutathione in the liver were decreased with increasing the dose of cadmium. The levels of cadmium in the liver and kidney, the levels of thiobarbituric acid-relative substances (TBARS) in the plasma and liver, the activities of aspartate transaminase (AST) and alanine transaminase (ALT) in the plasma, and the levels of blood urea nitrogen (BUN) and creatinine in the plasma of rats were increased with the increasing dose of cadmium. Hence, symptoms of cadmium toxicity in rats included loss of body weight, hepatotoxicity and nephrotoxicity. However, these toxic effects of cadmium were significantly reduced when the rats fed diet with supplement of taurine. Furthermore, the level of cadmium in the feces of rats treated with taurine and cadmium was higher than that of rats treated with cadmium alone. It indicated that taurine might play a role in reducing the toxic effect of cadmium in rats.

Effect of ginseng saponins on beta-amyloid-suppressed acetylcholine release from rat hippocampal slices

In view of the facts that ginseng has been shown to improve age-related memory deficits and beta-amyloid-related peptides have been suggested to play a significant role in memory degeneration in the elderly, the present study was carried out to examine the effect of various ginsenosides on beta-amyloid peptides-modulated acetylcholine (ACh) release, a key neurotransmitter in memory processing, from the hippocampal slices. Addition of beta-amyloid fragment(25 - 35) (0.01 - 1 microM) in the superfusion medium suppressed the K(+)-evoked [(3)H]-ACh release from the rat hippocampal slices in a concentration-related manner and about 40 % reduction in ACh outflow was observed when incubating with the highest concentration of an amyloid fragment (1 microM). Inclusion of the ginsenoside components Rb(1) (0.1 microM), but not Rg(1), caused a rightward shift of the concentration-response curve of beta-amyloid. The reversal of the beta-amyloid-inhibited ACh release by Rb(1) was not blocked by tetrodotoxin (1 microM) indicating that an interaction occurs at the cholinergic synapse. These results suggest that Rb(1) may elicit its anti-amnesic effect by minimizing the inhibitory effect of beta-amyloid peptides.