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Biomedical subjects

S Kuo

Publications and source records attributed to S Kuo.

At least 19 recordsLinked to original sources
PubMed2006

Influence of solution acidity and CaCl2 concentration on the removal of heavy metals from metal-contaminated rice soils.

Soil washing is considered a useful technique for remediating metal-contaminated soils. This study examined the release edges of Cd, Zn, Ni, Cr, Cu or Pb in two contaminated rice soils from central Taiwan. The concentrations exceeding the trigger levels established by the regulatory agency of Taiwan were Cu, Zn, Ni and Cr for the Ho-Mei soil and Pb for the Nan-Tou soil. Successive extractions with HCl ranging from 0 to 0.2 M showed increased release of the heavy metals with declining pH, and the threshold pH value below which a sharp increase in the releases of the heavy metals was highest for Cd, Zn, and Ni (pH 4.6 to 4.9), intermediate for Pb and Cu (3.1 to 3.8) and lowest for Fe (2.1), Al (2.2) and Cr (1.7) for the soils. The low response slope of Ni and Cr particularly for the rice soils make soil washing with the acid up to the highest concentration used ineffective to reduce their concentrations to below trigger levels. Although soil washing with 0.1 M HCl was moderately effective in reducing Cu, Pb, Zn and Cd, which brought pH of the soils to 1.1+/-0.1 (S.D.), the concurrent release of large quantities of Fe and Al make this remediation technique undesirable for the rice soils containing high clay. Successive washings with 0.01 M HCl could be considered an alternative as the dissolution of Fe and Al was minimal, and between 46 to 64% of Cd, Zn, and Cu for the Ho-Mei soil and 45% of Pb in the Na-Tou soil were extracted after four successive extractions with this dilute acid solution. The efficacy of Cd extraction improved if CaCl2 was added to the acid solution. The correlation analysis revealed that Cr extracted was highly correlated (P < 0.001) with Fe extracted, whereas the Cu, Ni, Zn, Cd or Pb extracted was better correlated (P < 0.001) with Al than with Fe extracted. It is possible that the past seasonal soil flooding and drainage in the soils for rice production was conducive to incorporating Cr within the structure of Fe oxide, thereby making them extremely insoluble even in 0.2 M HCl solution. The formation of solid solution of Ni with Al oxide was also possible, making it far less extractable than Cd, Zn, Cu, or Pb with the acid concentrations used.

Agriculture↗
PubMed2001

Effect of winter cover crops on soil nitrogen availability, corn yield, and nitrate leaching.

Biculture of nonlegumes and legumes could serve as cover crops for increasing main crop yield, while reducing NO3 leaching. This study, conducted from 1994 to 1999, determined the effect of monocultured cereal rye (Secale cereale L.), annual ryegrass (Lolium multiflorum), and hairy vetch (Vicia villosa), and bicultured rye/vetch and ryegrass/vetch on N availability in soil, corn (Zea mays L.) yield, and NO3-N leaching in a silt loam soil. The field had been in corn and cover crop rotation since 1987. In addition to the cover crop treatments, there were four N fertilizer rates (0, 67, 134, and 201 kg N ha(-1), referred to as N0, N1, N2, and N3, respectively) applied to corn. The experiment was a randomized split-block design with three replications for each treatment. Lysimeters were installed in 1987 at 0.75 m below the soil surface for leachate collection for the N 0, N 2, and N 3 treatments. The result showed that vetch monoculture had the most influence on soil N availability and corn yield, followed by the bicultures. Rye or ryegrass monoculture had either no effect or an adverse effect on corn yield and soil N availability. Leachate NO3-N concentration was highest where vetch cover crop was planted regardless of N rates, which suggests that N mineralization of vetch N continued well into the fall and winter. Leachate NO3-N concentration increased with increasing N fertilizer rates and exceeded the U.S. Environmental Protection Agency's drinking water standard of 10 mg N l(-1) even at recommended N rate for corn in this region (coastal Pacific Northwest). In comparisons of the average NO3-N concentration during the period of high N leaching, monocultured rye and ryegrass or bicultured rye/vetch and ryegrass/vetch very effectively decreased N leaching in 1998 with dry fall weather. The amount of N available for leaching (determined based on the presidedress nitrate test, the amount of N fertilizer applied, and N uptake) correlated well with average NO3-N during the high N leaching period for vetch cover crop treatment and for the control without the cover crops. The correlation, however, failed for other cover crops largely because of variable effectiveness of the cover crops in reducing NO3 leaching during the 5 years of this study. Further research is needed to determine if relay cover crops planted into standing summer crops is a more appropriate approach than fall seeding in this region to gain sufficient growth of the cover crop by fall. Testing with other main crops that have earlier harvest dates than corn is also needed to further validate the effectiveness of the bicultures to increase soil N availability while protecting the water quality.

Agriculture↗
PubMed2001

Benzyloxybenzaldehyde analogues as novel adenylyl cyclase activators.

Several benzyloxybenzaldehyde analogues were prepared and found to have significant inhibitory activity toward neutrophil superoxide formation. Consequently, these compounds were evaluated for cAMP-elevating capability. Among them, benzyloxybenzaldehyde (7), exhibiting activity equivalent to forskolin, was determined as an adenylyl cyclase activator since it elevates cAMP levels by activation of adenylyl cyclase but not by inhibition of phosphodiesterase. Having a chemical structure very different from known adenylyl cyclase activators, compound 7 is recommended by us for use as a new lead compound in the future development of adenylyl cyclase activators.

Adenylyl Cyclases↗
PubMed2001

Measuring the thickness of articular cartilage from MR images.

We have developed an algorithm to estimate and display the spatial distribution of the thickness of articular cartilage in human knees. We used a simulation to derive the most appropriate formula for estimating thickness in digital images. The algorithm was tested by imaging a thickness phantom and comparing the results with the known dimensions of the phantom. The results demonstrated that the maximum error encountered in estimating thickness is one pixel while the average error is 0.4 pixels. We imaged a human knee on a cadaver in two separate sessions and used the two image sets to derive thickness maps of the patellar articular cartilage. The thickness maps generated independently from these image sets were very similar, indicating the reliability of the method in deriving accurate thickness estimates. J. Magn. Reson. Imaging 2001;13:120-126.

Algorithms↗
PubMed2001

Differential appearance of T cell subsets in the large and small intestine of neonatal mice.

We examined the appearance of intestinal intraepithelial lymphocytes (IEL) during the first 12 wk of life to gain insight into postnatal factors that contribute to the differences found between IEL in the large and small intestines of adult mice. Intestinal T cells were very infrequent at birth, but increased in number in the large and small intestine during the first 4 wk of life and then stabilized. The small intestinal epithelium at 2 wk of age contained mostly T cell receptor (TCR) alphabeta+, CD2+ T cells, unlike IEL in adult mice, which were composed of nearly equal proportions of CD2-, TCR alphabeta+ and TCR gammadelta+ cells. Between 2 and 3 wk of age, TCR gammadelta+, CD2- IEL increased greatly in the small intestine, whereas TCR alphabeta+ cells expressing CD2 decreased. By contrast, IEL in the large intestine at 2 and 3 wk of age were mostly TCR alphabeta+, CD2+ T cells similar to large intestinal IEL in adult mice. And finally, the expression of CD69 increased earlier and to higher levels on TCR alphabeta+ and TCR gammadelta+ IEL in the small intestine than in the large intestine. Our results demonstrate that IEL in the large and small intestine are phenotypically similar during suckling and that differences between these populations are established after weaning. Furthermore, the earlier accumulation of IEL with an activated adult IEL phenotype in the small intestine suggests that these T cells mature or expand in the gut and contribute to the maturation of immune function during postnatal life in mice.

Animals↗
PubMed2000

Effect of fatty acids on the mycelial growth and polysaccharide formation by Ganoderma lucidum in shake flask cultures.

Fatty acids were added into the media to investigate their effects on the mycelial growth and polysaccharide formation by Ganoderma lucidum. The experiments were carried out in freely suspended cultures or immobilized cultures using shake flasks. The results indicate that the extent of stimulation or inhibition were associated with the types and levels of fatty acids. Oleic acid at the level of 0.15 g/100 ml led to a significant increase in cell concentration from 0.20 to 0.46 g/100 ml in a suspended culture and palmitic acid was of great advantage to polysaccharide production. In contrast, linoleic acid (0.1 g/100 ml) drastically suppressed both mycelial growth and polysaccharide formation. In immobilized cultures with fatty acids, the stimulation of mycelial growth remained the same level, but the enhancement of polysaccharide production became less. In addition, the growth of G. lucidum in the pattern of immobilization might be beneficial to the production of mycelia and polysaccharide.

Journal Article↗
PubMed2000

Cytokine-inducible enhancer with promoter activity in both the rat and human manganese-superoxide dismutase genes.

Diverse pro-inflammatory mediators regulate transcription of the gene (MnSOD) encoding the mitochondrial anti-oxidant protein manganese-superoxide dismutase. Understanding the regulation of this gene is crucial to comprehending its role in cytoprotection. In transfected lung epithelial cells, a human-growth-hormone reporter gene system was utilized to identify a potential enhancer in the MnSOD genomic fragment previously shown to contain multiple DNase-I-hypersensitive sites. Northern analysis demonstrated a 10-20-fold increase in response to pro-inflammatory mediators. Inclusion of the MnSOD genomic fragment in reporter constructs was necessary to mimic these stimulus-dependent endogenous levels. The inducible enhancer element was localized to a 260 bp fragment in intron 2, coinciding with a previously defined DNase-I-hypersensitive site. This element functions in an orientation- and position-independent manner as well as with the heterologous thymidine kinase promoter. In addition, we have demonstrated that a homologous sequence within the human MnSOD gene exhibits identical enhancer activity. A novel characteristic of the rat and human enhancer elements involves the ability to promote cytokine-inducible transcription in the absence of a classical promoter.

Animals↗
PubMed2000

Biological energy from the igneous rock enhances cell growth and enzyme activity.

Some effects from natural resources might be ignored and unused by humans. Environmental hormesis could be a phenomena necessary to bio-organism existence on earth. Since 1919, radiation and some heavy metal hormesis from the environment were proved in various reports. In this study, igneous rock with very low radioactivity and high ferrous activity was measured by multichannel analyzer and inductively coupled plasma analyzer. The water treated by igneous rock, both directly soaked or indirectly in contact, induced increased activities of glucose oxidase, catalase, peroxidase, and superoxide dismutase. It also increased cell growth of SC-M1, HCT-15, Raji, and fibroblast cell lines. The water after treatment of igneous rock had no change in pH values, but displayed decreased conductivity values. We assume that the igneous rock could transfer energy to water to change the molecular structure or conformation of water cluster, or by radiation hormesis effect could then induce increased enzyme activity and cell growth. It is also possible that the energy from rock may combine radiation hormesis with other transferable biological energy forms to change water cluster conformation.

Animals↗
PubMed1999

In vivo architecture of the manganese superoxide dismutase promoter.

Mitochondrial manganese superoxide dismutase (Mn-SOD) is the primary cellular defense against damaging superoxide radicals generated by aerobic metabolism and as a consequence of inflammatory disease. Elevated expression of Mn-SOD therefore provides a potent cytoprotective advantage during acute inflammation. Mn-SOD contains a GC-rich and TATA/CAAT-less promoter characteristic of a housekeeping gene. In contrast, however, Mn-SOD expression is dramatically regulated in a variety of cells by numerous proinflammatory mediators, including lipopolysaccharide, tumor necrosis factor-alpha, and interleukin-1. To understand the underlying regulatory mechanisms controlling Mn-SOD expression, we utilized DNase I-hypersensitive (HS) site analysis, which revealed seven hypersensitive sites throughout the gene. Following high resolution DNase I HS site analysis, the promoter was found to contain five HS subsites, including a subsite that only appears following stimulus treatment. Dimethyl sulfate in vivo footprinting identified 10 putative constitutive protein-DNA binding sites in the proximal Mn-SOD promoter as well as two stimulus-specific enhanced guanine residues possibly due to alterations in chromatin structure. In vitro footprinting data implied that five of the binding sites may be occupied by a combination of Sp1 and gut-enriched Kr uppel-like factor. These studies have revealed the complex promoter architecture of a highly regulated cytoprotective gene.

Animals↗
PubMed1996

Antimutagenic activity of extracts from Japanese eggplant.

Using the Salmonella/microsome assay, the antimutagenic effects of specific components of the extracts from eggplant fruits were investigated. The eggplant fruit juice exhibited an antimutagenic activity against 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) induced mutagenicity. In some of the fractions extracted with several organic solvents (acetone, petroleum ether, ethyl acetate; and methanol), the activity was recognized. No mutagenicity or toxicity for Salmonella typhimurium TA98 in the presence of S9 mixture was observed with any of the extracts. It is suggested that there are multiple components of the activities that exist in the eggplant fruit. We isolated lutein from the 84% methanol (methanol/water, v/v) layer, pheophorbide or chlorophyllide from the 70% methanol layer and tannins containing sugar-moieties from the water layer. Pheophytin a and b, Mg-free derivatives of chlorophyll a and b, were isolated from the petroleum ether layer as possible antimutagens. The pheophytin a with S9 mix inhibited by 30-40% the mutagenicity of Trp-P-2.

Antimutagenic Agents↗
PubMed1994

Endogenous excitatory amino acids tonically stimulate striatal acetylcholine release through NMDA but not AMPA receptors.

The effect of stimulation and blockade of excitatory amino acid receptors on striatal acetylcholine release was examined using in vivo microdialysis in awake, freely moving rats. Local perfusion with the NMDA receptor antagonists CPP and MK-801 reduced striatal acetylcholine release, while NMDA itself enhanced striatal acetylcholine release. Co-perfusion with MK-801 blocked the NMDA-induced increase in acetylcholine release. The AMPA/kainate antagonists NBQX and GYKI 52466 alone did not decrease striatal acetylcholine release, although AMPA increased acetylcholine release. Co-perfusion with NBQX reduced the AMPA-induced elevation in acetylcholine release. These findings suggest that endogenous excitatory amino acids tonically stimulate striatal acetylcholine release through NMDA but not AMPA receptors.

Acetylcholine↗
PubMed1994

Detergent-enhanced dissociation of endogenous peptides from PI-DRB1*0401.

A variety of detergents have been shown to catalyze the dissociation of bound peptides from a soluble from of DRB1*0401. By using a class II molecule lacking the hydrophobic transmembrane region, the need for solubilizing the transmembrane protein was removed and enabled the specific interaction between the class II protein and the amphiphile to be identified. The presence of detergent increased the rate of association of added peptide and the percent occupancy of the receptor, presumably because the dissociation of endogenous peptide was the rate-limiting step in binding. The data help explain the differences reported between peptide binding to class II proteins on the surface of cells and binding to class II proteins solubilized in detergent. The interaction did not correlate with the critical micellar concentration of the detergent nor were all amphiphilic structures equally effective, consistent with a specific interaction between the amphiphile and the MHC class II protein. Of the eight detergents examined, octyl glucoside was the most efficient. These experiments did not distinguish between an allosteric mechanism or direct competition with the peptide for binding.

Amino Acid Sequence↗
PubMed1994

Excitatory amino acid receptor antagonists modify regional cerebral metabolic responses to levodopa in 6-hydroxydopamine-lesioned rats.

Excitatory amino acid receptor antagonists have been proposed as novel therapeutic agents to be used with levopoda in the treatment of Parkinson's disease. We examined the neural substrates for the interaction between levodopa and antagonists of either the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid or N-methyl-D-aspartate type of excitatory amino acid receptor using 2-deoxyglucose autoradiography. Thus, we compared the effects of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (10 mg/kg, i.v.) and the N-methyl-D-aspartate antagonist MK-801 (0.1 mg/kg, i.v.) on cerebral metabolic responses to levodopa (25 mg/kg, i.v., with 12.5 mg/kg benserazide) in rats with a unilateral nigrostriatal pathway lesion. Levodopa increased glucose utilization ipsilateral to the lesion in substantia nigra pars reticula (up to 104%), entopeduncular nucleus (up 90%) and subthalamic nucleus (up 30%), indicating that levodopa alters striatal output through the striatonigral, striatoentopeduncular and striatopallidal pathways. Levodopa also decreased metabolic rate in lateral habenula (down 39%), a target of projections from entopeduncular nucleus, implying a reduction in basal ganglia output. 2,3-Dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline and MK-801 by themselves did not affect glucose utilization in any of these regions. Pretreatment with 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline reduced the effect of levodopa in substantia nigra pars reticulata but not in entopeduncular nucleus or subthalamic nucleus, while MK-801 attenuated the effect of levodopa in all three of these structures; neither 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline nor MK-801 altered the effect of levodopa in lateral habenula. When given at the same doses to a separate group of lesioned animals, neither 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline nor MK-801 affected rotational behavior elicited by levodopa. These findings indicate that alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid and N-methyl-D-aspartate receptor antagonists differentially modify dopamine receptor-mediated striatal output. alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor blockade may preferentially attenuate the effect of dopamine receptor activation on the striatonigral pathway, while N-methyl-D-aspartate blockade appears to reduce the actions of dopamine on the striatonigral, striatoentopeduncular and striatopallidal pathways.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Dopamine D1 receptor-stimulated release of acetylcholine in rat striatum is mediated indirectly by activation of striatal neurokinin1 receptors.

Activation of dopamine D1 receptors is thought to stimulate release of striatal acetylcholine (ACh) indirectly, possibly through local release of substance P which, in turn, may enhance release of ACh. To test this hypothesis, in vivo microdialysis was used to assess the effect of neurokinin1 (NK1) receptor blockade on D1 agonist-induced increases in ACh release in the striatum of awake, freely moving rats with and without a unilateral 6-hydroxydopamine-induced lesion of the nigrostriatal pathway. Local perfusion with the D1 agonist (+-)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3- benzazepine-7,8-diol hydrochloride (SKF 38393; 1-25 microM for 20 min) increased striatal ACh release in both intact rats and rats with a 6-hydroxydopamine-induced lesion, although the increase was greater in magnitude in rats with a lesion. Local application of the NK1 antagonist, (2S,3S)-cis-2-(diphenylmethyl)-N- [(methoxyphenyl)methyl]-1-azabicyclo[2.2.2]octan-3-amine (CP-96,345; 10 and 25 microM), but not its less active enantiomer (2R,3R)-cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl)methyl]-1- azabicyclo[2.2.2]octan-3-amine (CP-96,344; 10 and 25 microM), decreased the elevation in ACh induced by SKF 38393 in both intact rats and rats treated with 6-hydroxydopamine. Systemic administration of the NK1 antagonist 17-beta-hydroxy-17-a-androstanol[3.2- b]pyrimidol[1,2-a]benzimidazole hydrochloride (WIN 51,708; 20 mg/kg i.p.) also reduced the increase in ACh release induced by local perfusion of SKF 38393.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1993

GABAA and GABAB receptors differentially regulate striatal acetylcholine release in vivo.

Microdialysis was used to study the effects of selective GABAergic agents on striatal acetylcholine (ACh) release in awake, freely moving rats. Local perfusion with the GABAA agonist muscimol dramatically reduced striatal ACh release, while the GABAB agonist baclofen caused only minor decreases in ACh release. Co-perfusion with the GABAA antagonist bicuculline diminished the muscimol-induced decrease in ACh release. Likewise, co-perfusion with the GABAB antagonist 2-hydroxysaclofen attenuated the baclofen-induced reduction in ACh release. Bicuculline alone markedly increased striatal ACh release, but 2-hydroxysaclofen by itself had no effect. These results suggest that GABA tonically regulates striatal ACh release primarily through stimulation of inhibitory GABAA receptors.

Acetylcholine↗
PubMed1993

Extracellular interception of mutagens.

Extracellular interception of mutagens by excreted enzymes or by chemical agents that react with or bind to formed mutagens provides an important means of defense against chemical mutagens/carcinogens. Kada and Shimoi have classified molecules that function in this manner as "desmutagens," and many of them are natural cellular metabolites. Among the specific mechanisms that such agents may employ are: prevention of the activation of "promutagens" to mutagens; stimulation of enzymes (e.g., glutathione-S-transferase) that catalyze the binding/inactivation of damaging electrophiles; direct binding and concomitant inactivation of promutagens or mutagens; interference with uptake of mutagens into cells; etc. De Flora and Ramel have provided an excellent discussion of the mechanisms of these agents and a proposed classification scheme. Drawing on work from our own laboratories and other recent examples in the literature, several examples of mechanistic approaches to these studies using natural plant-derived materials, e.g., humic acid, Glycyrrhiza glabra extract, glutathione, and bioflavonoids, are also described. Antioxidants and agents that conjugate electrophiles will be among the modes of action described for obtaining the goal of intercepting mutagens/carcinogens.

Animals↗
PubMed1993

N-methyl-D-aspartate receptor blockade differentially modifies regional cerebral metabolic responses to D1 and D2 dopamine agonists in rats with a unilateral 6-hydroxydopamine lesion.

Dopamine and the excitatory amino acids play important roles in the control of motor behavior by the basal ganglia; elucidating the manner in which these transmitter systems interact may provide new therapeutic approaches to the treatment of movement disorders such as Parkinson's disease. The 2-deoxyglucose autoradiographic technique was used to examine the effect of N-methyl-D-aspartate receptor blockade on regional cerebral metabolic responses to D1 and D2 dopamine receptor stimulation in rats with a unilateral 6-hydroxydopamine lesion of the nigrostriatal pathway. The D1 agonist SKF 38393 (5 mg/kg, i.v.) increased glucose utilization markedly in entopeduncular nucleus and substantia nigra pars reticulata ipsilateral to the lesion, while the D2 agonist quinpirole (1 mg/kg, i.v.) had no effect in these striatal output regions. SKF 38393 and quinpirole reduced 2-deoxyglucose uptake to a similar extent in the lateral habenula, a region which receives afferent input from entopeduncular nucleus; quinpirole also decreased glucose utilization bilaterally in nucleus accumbens. Pretreatment with the noncompetitive N-methyl-D-aspartate receptor antagonist MK-801 (0.1 mg/kg, i.v.), which had little effect on cerebral metabolism by itself, reduced the effect of SKF 38393 in entopeduncular nucleus and substantia nigra pars reticulata and prevented the effect of quinpirole in nucleus accumbens. MK-801 did not alter the SKF 38393-induced reduction in glucose utilization in lateral habenula, but did reduce the effect of quinpirole in this structure. When these drugs were administered in the same manner to a separate group of lesioned animals, MK-801 did not affect rotational behavior elicited by SKF 38393, but completely eliminated contralateral rotation and actually caused some ipsilateral rotation in response to quinpirole. These findings indicate that D1 and D2 receptor-associated brain mechanisms are differentially influenced by N-methyl-D-aspartate receptor stimulation. D2-mediated behavioral and cerebral metabolic responses appear to require concurrent N-methyl-D-aspartate receptor stimulation. On the other hand, the preservation of D1-mediated rotational behavior and reduced lateral habenula glucose metabolism in the presence of MK-801 despite attenuation of the effects of the D1 agonist in entopeduncular nucleus and substantia nigra pars reticulata suggests that D1 receptor-regulated neuronal pathways exhibit varying degrees of sensitivity to N-methyl-D-aspartate receptor blockade.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗