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排序方式: 共有107条查询结果,搜索用时 31 毫秒
31.
Two cDNA clones for jasmonic acid (JA)-responsive genes, RRJ1 and RRJ2, were isolated by differential screening from suspension-cultured rice cells treated with JA for 2 h. The putative RRJ1 protein is completely identical to that of a putative rice cystathionine gamma-lyase, while the putative RRJ2 protein is highly similar in sequence to a rice pyruvate decarboxylase, PDC1.  相似文献   
32.
A search in the Bacillus subtilis genome sequence found that the gene designated yclM encode(s) a protein showing significant identity in amino acid sequence to aspartate kinases. When yclM was introduced into Escherichia coli cells deficient in all three aspartate kinase genes, production of a protein with molecular size 50 kDa, which was similar to the value deduced from the nucleotide sequence of the gene, was observed. Expectedly, the protein purified to homogeneity had aspartate kinase activity. The enzyme was significantly inhibited by simultaneous addition of both threonine and lysine, which is a typical feature of aspartate kinase III of B. subtilis. The enzyme was very unstable in 10 mM tris-HCl (pH 7.5) buffer, but was stabilized by addition of 500 mM ammonium sulfate. Although all the aspartate kinases so far investigated are oligomeric enzymes, this aspartate kinase was suggested to be a monomer.  相似文献   
33.
Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that starts in early childhood and has a comprehensive impact on psychosocial activity and education as well as general health across the lifespan. Despite its prevalence, the current diagnostic criteria for ADHD are debated. Saccadic eye movements are easy to quantify and may be a quantitative biomarker for a wide variety of neurological and psychiatric disorders, including ADHD. The goal of this study was to examine whether children with ADHD exhibit abnormalities during a visually guided pro-saccadic eye-movement and to clarify the neurophysiological mechanisms associated with their behavioral impairments. Thirty-seven children with ADHD (aged 5–11 years) and 88 typically developing (TD) children (aged 5–11 years) were asked to perform a simple saccadic eye-movement task in which step and gap conditions were randomly interleaved. We evaluated the gap effect, which is the difference in the reaction time between the two conditions. Children with ADHD had a significantly longer reaction time than TD children (p < 0.01) and the gap effect was markedly attenuated (p < 0.01). These results suggest that the measurement of saccadic eye movements may provide a novel method for evaluating the behavioral symptoms and clinical features of ADHD, and that the gap effect is a potential biomarker for the diagnosis of ADHD in early childhood.  相似文献   
34.

Purpose

To assess the relationship of intraocular forward scattering and corneal higher-order aberrations (HOAs) with best spectacle corrected visual acuity (BSCVA) after Descemet’s stripping automated endothelial keratoplasty (DSAEK), and to compare these parameters between DSAEK and non-Descemet’s stripping automated endothelial keratoplasty (n-DSAEK) groups.

Methods

This retrospective study enrolled thirty eyes of 30 consecutive patients who underwent standard DSAEK, and who underwent successful phacoemulsification with intraocular lens implantation before DSAEK. The mean age at the time of surgery was 71.7 ± 10.4 years. We quantitatively evaluated the objective scattering index (OSI) using the double-pass instrument (OQAS II, Visiometrics) and corneal HOAs using Hartmann-Shack aberrometry (KR-9000PW, Topcon) 3 months postoperatively.

Results

The mean OSI, corneal HOAs, and logMAR BSCVA 3 months after DSAEK were 7.91 ± 3.58, 0.43 ± 0.27 μm, and 0.32 ± 0.25, respectively. We found a significant correlation between the OSI and logMAR BSCVA (Spearman correlation coefficient r=0.714, p<0.001), but no significant association between corneal HOAs and logMAR BSCVA 3 months postoperatively (r=0.209, p=0.267). We found no significant differences in any postoperative parameters between the DSAEK and n-DSAEK groups (p>0.05).

Conclusions

Our pilot study demonstrated that the postoperative corrected visual acuity was significantly correlated with intraocular forward scattering, but not with corneal HOAs in post-DSAEK eyes, suggesting that intraocular forward scattering plays a more essential role in postoperative visual performance than corneal aberrations after DSAEK. The detailed visual performance, such as HOAs and intraocular scattering, after n-DSAEK appears to be essentially equivalent to that after DSAEK.  相似文献   
35.

Purpose

To objectively compare the optical quality and the intraocular scattering after implantation of the posterior chamber phakic implantable collamer lens (Visian ICL™, STAAR Surgical) with and without a central artificial hole for moderate to high ametropia.

Methods

This retrospective study comprised 28 eyes of 28 consecutive patients undergoing Hole ICL implantation (mean age ± standard deviation, 30.3±5.8 years), and 24 age-matched eyes of 24 patients undergoing conventional ICL implantation (age, 30.4±6.1 years). We quantitatively assessed the postoperative values of MTF cutoff frequency, Strehl ratio, objective scattering index (OSI), and OQAS values (OVs), using an Optical Quality Analysis System™. We compared these postoperative variables between the two groups.

Results

The mean MTF cutoff frequency, Strehl ratio, OSI, OV100%, OV 20%, and OV9%, were 26.21±8.32 cycles/degree, 0.16±0.04, 1.16±0.57, 0.87±0.28, 0.80±0.35, and 0.80±0.33, respectively, 3 months after Hole ICL implantation. We found no significant differences in the MTF cutoff frequency (Mann Whitney U test, p = 0.59), the Strehl ratio (p = 0.82), the OSI (p = 0.63), or the OVs at contrasts of 100% (p = 0.58), 20% (p = 0.40), and 9% (p = 0.87), between the two groups.

Conclusions

Both Hole ICL and conventional ICL implantation provides an excellent optical performance including intraocular scattering. Newly developed Hole ICL implantation appears to be essentially equivalent in the optical quality variables to conventional ICL implantation, suggesting that the presence of the central artificial hole does not significantly affect the optical quality and the intraocular scattering after surgery.  相似文献   
36.
The neutral fraction of cigarette smoke Components, produced in constant-volume continuous smoking by an artificial smoking device, was sub-fractionated into alcohols, acid-, alcohol- and phenol-components of esters, unsaponifiable matters and hydrocarbons. From these sub-fractions ethyl alcohol, benzyl alcohol, β-phenylethyl alcohol and ethyl acetate were first isolated as their crystalline derivatives and then identified by their melting points, infrared spectra and elementary analyses. It is worth to note that the presence of these compounds in tobacco smoke has not yet been reported in the literature.  相似文献   
37.
38.
The effects of several inorganic salts on the combustion of cigarette and the transfer of nicotine into cigarette smoke have been investigated. Ferric, ferrous, ammonium, magnesium salts and chlorides or sulfates depress the combustibility. Contrary to this, potassium, calcium salts, nitrates and carbonates promote it. The combustion-zone temperatures of cigarettes are within the range from 815°C to 857°C, they are not significantly affected by an addition of inorganic salts. Magnesium nitrate, zinc nitrate and potassium phosphate improve the whiteness of cigarette ash, but the other salts rather darken it. Any relations, however, are not recognized between the whiteness of ash and combustibility of cigarettes. The amounts of nicotine transferred into smoke can be reduced by an addition of inorganic salts, among which magnesium is the most effective.  相似文献   
39.
The role of protease in streptolysin S formation   总被引:4,自引:0,他引:4  
Production of streptolysin S by streptococci was found to be inhibited by treatment with protease inhibitors, tosylphenylalanine chloromethyl ketone (TPCK), tosyllysine chloromethyl ketone (TLCK), or phenylmethylsulfonyl fluoride (PMSF), even in the presence of the inducer oligonucleotides. Other protease inhibitors, antipain, leupeptin, or pepstatin were found to have little or no effect. Trypsin reversed the effect of TPCK or TLCK. The reversal was dependent upon the amount of added trypsin and the incubation time at 37 degrees C, suggesting that a protease activity was involved in the hemolysin formation. The effect of trypsin was not observed if chloramphenicol was also added, suggesting that a precursor of streptolysin S was processed as it was synthesized and released into medium as the active hemolysin, by the concerted action of a protease and inducer oligonucleotides. Experiments with the subcellular fractions of streptococci indicated that the streptolysin precursor was localized in the insoluble fraction and the "processing" protease in the supernatant fraction.  相似文献   
40.
A NADP(+)-dependent 3 beta-hydroxysteroid dehydrogenase activity was localized in the microsomal fraction of rat liver. This enzyme was solubilized and separated completely from 3 alpha-hydroxysteroid dehydrogenase by Matrex red A column chromatography. Partially purified 3 beta-hydroxysteroid dehydrogenase catalyzed the oxidation and reduction between the 3 beta-hydroxyl and 3-ketonic group of steroids or bile acids having no double bond in the A/B ring, but was inactive toward 3 alpha-hydroxyl group. The enzyme required NADP+ for oxidation and NADPH for reduction. The activity was inhibited by p-chloromercuribenzoic acid or p-chloromercuribenzenesulfonic acid at the concentration of 10(-4) M. The molecular weight of the enzyme was estimated to be about 43,000 by Sephadex G-200 column chromatography. From these results, it is concluded that the enzyme is a new type of microsomal NADP+:3 beta-hydroxysteroid dehydrogenase.  相似文献   
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