Biomedical subjects
Publications and source records attributed to Min Shi.
In the presence of DABCO (30 mol%), the addition of various selenosulfonates to alpha,beta-unsaturated ketones proceeded smoothly to give the corresponding adducts in good yields under mild conditions.
The chiral nitrogen Lewis base, tricyclic cinchona alkaloid derivative TQO, is an effective promoter in the catalytic, asymmetric aza-Baylis-Hillman reaction of N-sulfonated imines Ar-CH=NR' 1 (R' = Ts, Ms, Ns, SES) with various activated olefins such as methyl vinyl ketone (MVK), ethyl vinyl ketone (EVK), acrolein, methyl acrylate, phenyl acrylate, or alpha-naphthyl acrylate to give the corresponding adducts in moderate to good yields with good to high ee (up to 99 %) at -30 degrees C or 45 degrees C in various solvents, including DMF/MeCN (1:1, v/v). The first such reaction of 1 with the simplest Michael acceptor MVK and methyl acrylate has been achieved with excellent enantioselectivity. The adducts derived from MVK and EVK had the opposite absolute configuration to those from acrolein, methyl acrylate, phenyl acrylate, and alpha-naphthyl acrylate. A plausible mechanism has been proposed on the basis of previous reports and the authors' investigations. An effective bifunctional chiral nitrogen Lewis base-Brønsted acid system has been revealed in this type of aza-Baylis-Hillman reaction.
We used cDNA microarrays containing approximately 9,000 unigenes to identify 486 salt responsive expressed sequence tags (ESTs) (representing approximately 450 unigenes) in shoots of the highly salt-tolerant rice variety, Nona Bokra (Oryza sativa L. ssp. Indica pv. Nona). Some of the genes identified in this study had previously been associated with salt stress. However the majority were novel, indicating that there is a great number of genes that are induced by salt exposure. Analysis of the salt stress expression profile data of Nona provided clues regarding some putative cellular and molecular processes that are undertaken by this tolerant rice variety in response to salt stress. Namely, we found that multiple transcription factors were induced during the initial salt response of shoots. Many genes whose encoded proteins are implicated in detoxification, protectant and transport were rapidly induced. Genes supporting photosynthesis were repressed and those supporting carbohydrate metabolism were altered. Commonality among the genes induced by salt exposure with those induced during senescence and biotic stress responses suggests that there are shared signaling pathways among these processes. We further compared the transcriptome changes of the salt-sensitive cultivar, IR28, with that of Nona rice. Many genes that are salt responsive in Nona were found to be differentially regulated in IR28. This study identified a large number of candidate functional genes that appear to be involved in salt tolerance and further examination of these genes may enable the molecular basis of salt tolerance to be elucidated.
OBJECTIVE: To investigate the mutations of phenylalanine hydroxylase (PAH) gene in the cases of classical phenylketonuria (PKU). METHODS: The exons 3-12 of the PAH gene in 32 PKU patients from Inner Mongolia were studied by using PCR-single strand conformation polymorphism technique and DNA direct sequencing. RESULTS: Fourteen point mutations were identified. The frequencies of mutations were R243Q (12/64), Y356X (6/64), Y204C (5/64), R261Q (2/64), Y161S (2/64), R252Q (1/64), R111X (2/64), D282G (1/64), S303P (1/64), G239D (1/64), R413P (1/64), IVS7nt+2 (2/64), IVS4nt+3 (1/64) and IVS9nt+34 (2/64). Two novel mutations IVS4nt+3 (G>C) and IVS9nt+34 (G>A) were first found. The S303P (T>C) and D282G (A>G) were first documented in Chinese PAH gene. CONCLUSION: This study demonstrated the variety of the mutation type PAH gene of PKU in Inner Mongolia population, and confirmed that R243Q, Y356X, Y204C were the hot spots of PAH gene mutation.
Through atomic absorption detector, the contents of Pb and Cd in chicken granules and gourmet powder were determined. From the result it was found that there are differing contents of pollutant elements, i. e. 0.00-10.00 microg x mL(-1) for Pb and 0.00-4.00 microg x mL(-1) for Cd, respectively. The relative standard deviations of Pb and Cd are 3.15% and 4.26%, respectively. At the same time, a recovery experiment for Pb and Cd in chicken granules and gourmet powder were performed, and the recoveries are 96.7%-102.1% for Pb and 91.9%-107.6% for Cd, respectively.
OBJECTIVE: To perform the proteome analysis of conditioned medium prepared from mouse embryonic fibroblast feeder layers by 2-dimensional (2D) electrophoresis and mass spectrometry and to find out the possible differentiation-inhibitory factor in conditioned medium. METHODS: Feeder layers were prepared by 60Co gamma-irradiation on mouse embryonic fibroblast. Insulin-transferrin-sodium selenite supplemented medium was used to culture the feeder layers for 24 hours. The condioned medium prepared from mouse embryonic fibroblast feeder layers were made into powder by lyophilization, the redissolved solution was applied to Sephadex G-50 gel filtration chromatography, and then cold acetone was used to precipitate the proteins in the eluted solution. The protein samples were applied to 2D electrophoresis. The 2D images were analyzed by 2D image analysis software. Selected protein spots were digested by trypsin, analyzed by mass spectrometry, and then searched against the NCBInr batabase using Mascot MS/MS Ions Search. RESULTS: The protein samples extracted from mouse embryonic fibroblast feeder layers conditioned medium could be used for 2D electrophoresis. On 2D images, there were (221+/-67) spots. Most of the proteins were located in the region of MW 20 approximately 70 kD, pI 4 approximately 8. Using mass spectrometry, we preliminarily identified 13 spots: 3 keratins, 3 transferrins, 1 trypsin precursor, 2 unknown proteins (3 spots), 1 connexin 46, 1 beta-galactoside binding protein, and 1 secreted protein, acidic and rich in cysteine. CONCLUSION: Conditioned medium prepared from mouse embryonic fibroblast feeder layers contain beta-galactoside binding protein and secreted protein, acidic and rich in cysteine.
A novel carbolithiation of gem-aryl disubstituted methylenecyclopropanes was disclosed by the treatment with BuLi in THF at -78 degree C. The corresponding addition products can be obtained in good to high yields by quenching with various electrophiles.
We reported previously that intravenously administered d-glucose acts in the central nervous system to inhibit gastric motility induced by hypoglycemia in anesthetized rats. The purpose of this study was to determine whether this effect is due to inhibition of dorsal motor nucleus of the vagus (DMV) cholinergic motoneurons, which synapse with postganglionic cholinergic neurons, or to excitation of DMV cholinergic neurons, which synapse with postganglionic nonadrenergic, noncholinergic (NANC) neurons, particularly nitrergic neurons. Three approaches were employed: 1) assessment of the efficacy of d-glucose-induced inhibition of gastric motility in hypoglycemic rats with and without inhibition of nitric oxide synthase [10 mg/kg iv nitro-l-arginine methyl ester (l-NAME)], 2) assessment of the efficacy of intravenous bethanechol (30 mug.kg(-1).min(-1)) to stimulate gastric motility in hypoglycemic rats during the time of d-glucose-induced inhibition of gastric motility, and 3) determination of c-Fos expression in DMV neurons after intravenous d-glucose was administered to normoglycemic rats. Results obtained demonstrated that l-NAME treatment had no effect on d-glucose-induced inhibition of gastric motility; there was no reduction in the efficacy of intravenous bethanechol to increase gastric motility, and c-Fos expression was not induced by d-glucose in DMV neurons that project to the stomach. These findings indicate that excitation of DMV cholinergic motoneurons that synapse with postganglionic NANC neurons is not a significant contributing component of d-glucose-induced inhibition of gastric motility.
The enantioselective conjugate addition of dialkylzinc or diphenylzinc to enones was catalyzed by a copper(I)-axially chiral binaphthylthiophosphoramide or binaphthylselenophosphoramide ligand system at room temperature (20 degrees C) or 0 degrees C, affording the Michael adducts in high yields with excellent ee for cyclic and acyclic enones. The enantioselectivity and reaction rate achieved here are one of the best results yet for the Cu-catalyzed conjugate addition to enones. It was revealed that this series of chiral phosphoramides was a novel type of S,N-bidentate ligands on the basis of (31)P NMR and (13)C NMR spectroscopic investigations. The mechanism of this asymmetric conjugate addition system has been investigated as well. We found that the acidic proton of phosphoramide in these chiral ligands play a significant role in the formation of the active species. A bimetallic catalytic process has been proposed on the basis of previous literature. The linear effect of product ee and ligand ee further revealed that the active species is a monomeric Cu(I) complex bearing a single ligand [Cu(I):ligand 1:1].
The reactions of methylenecyclopropanes with diphenyl diselenide give ring-opened products in good yields at 150 [degree]C under nitrogen atmosphere for 3 h; the products can further undergo oxidative cyclization with hydrogen peroxide to furnish 3-phenylselenyl-2,5-dihydrofurans in moderate yields (three steps) at room temperature in CH(2)Cl(2) for 5 h; a plausible reaction mechanism has been proposed.
BACKGROUND: Cleft lip or palate (or the two in combination) is a common birth defect that results from a mixture of genetic and environmental factors. We searched for a specific genetic factor contributing to this complex trait by examining large numbers of affected patients and families and evaluating a specific candidate gene. METHODS: We identified the gene that encodes interferon regulatory factor 6 (IRF6) as a candidate gene on the basis of its involvement in an autosomal dominant form of cleft lip and palate, Van der Woude's syndrome. A single-nucleotide polymorphism in this gene results in either a valine or an isoleucine at amino acid position 274 (V274I). We carried out transmission-disequilibrium testing for V274I in 8003 individual subjects in 1968 families derived from 10 populations with ancestry in Asia, Europe, and South America, haplotype and linkage analyses, and case-control analyses, and determined the risk of cleft lip or palate that is associated with genetic variation in IRF6. RESULTS: Strong evidence of overtransmission of the valine (V) allele was found in the entire population data set (P<10(-9)); moreover, the results for some individual populations from South America and Asia were highly significant. Variation at IRF6 was responsible for 12 percent of the genetic contribution to cleft lip or palate and tripled the risk of recurrence in families that had already had one affected child. CONCLUSIONS: DNA-sequence variants associated with IRF6 are major contributors to cleft lip, with or without cleft palate. The contribution of variants in single genes to cleft lip or palate is an important consideration in genetic counseling.
Dietary fructose, NaCl, and/or saturated fat have been correlated with mean arterial pressure (MAP) rises in sensitive strains of rats. Dysregulation of sodium and/or water reabsorption by the kidney may contribute. Using radiotelemetry and parallel semiquantitative immunoblotting, we examined the effects of various diets on MAP and the regulation of abundance of the major renal sodium and water transport proteins in male Sprague-Dawley rats. In study 1, rats ( approximately 275 g) were fed one of four diets for 4 wk (n = 6/group): 1) control, 2) 65% fructose, 3) control + added NaCl (2.59%), or 4) fructose + NaCl. In study 2, 5% butter (fat) was added to the above four diets. Both fat and NaCl, but not fructose, caused modest rises in MAP (5-10 mmHg) and increased the day-to-night ratio in diastolic blood pressure. NaCl or fructose increased kidney size. Creatinine clearance was increased by salt or fat, and fractional excretion of sodium was decreased by fat. In study 1, high NaCl markedly reduced plasma renin and aldosterone and its regulated proteins in whole kidney, i.e., the thiazide-sensitive Na-Cl cotransporter and the alpha- and gamma (70-kDa band)-subunits of the epithelial sodium channel. These effects were blunted by fat. Fructose increased the abundance of the sodium phosphate cotransporter, whereas it decreased the bumetanide-sensitive Na-K-2Cl cotransporter and aquaporin-2. Overall, doubling of dietary fat appeared to impair dietary sodium adaptation, i.e., blunt the downregulation of aldosterone-mediated effects, thus allowing blood pressure to rise at an accelerated rate.
The reaction of methylenecyclopropanes 1 with phenylsulfenyl chloride or phenylselenyl chloride gives (cyclobut-1-enylsulfanyl)benzene or (cyclobut-1-enylselanyl)benzene along with ring-opened product in good total yields at 0 degrees C in various solvents. A plausible mechanism has been proposed.
Methylenecyclopropanes (MCPs) 1 can react with aldehydes and aldimines to give the corresponding indene, THF, and pyrrolidine cycloaddition products in the presence of BF(3).OEt(2) under mild reaction conditions.
This paper describes several highly efficient aza-Baylis-Hillman reactions of N-tosylated imines with MVK, acrolein, and phenyl acrylate or alpha-naphthyl acrylate in the presence of a Lewis base. In most cases, the reaction can be completed within 1 h using the appropriate Lewis base catalyst. An efficient method to synthesize beta-amino ketones, aldehydes and esters in high yields and short reaction time has been developed.
The reaction of aromatic MCPs with sulfonamides catalyzed by Lewis acids affords the corresponding ring-opened homoallylic sulfonamides in good yields and the reaction of aliphatic MCPs with sulfonamides gives the corresponding pyrrolidine derivatives under the same conditions. Through deuterium-labeling experiments, we found that the reaction process is involved with the rearrangement of a cyclopropylcarbinyl cation and a nonclassic carbonium ion.
BACKGROUND: The addition of DNA analysis to epidemiologic studies that have traditionally incorporated demographic and interview data can provide additional power and open new avenues for investigation. DNA can be obtained from a variety of tissues, but each has attendant variation in sample quantity, quality, and cost of acquisition. Analytic approaches for DNA genotyping are under constant development, but current applications allow small amounts (less than 2 ng per assay) of DNA to be used for genotyping. METHODS: In this report, we designed effective assays for a spectrum of genes using either kinetic polymerase chain reaction (PCR) or molecular beacon applications. We also investigated the extent to which DNA use and reagent cost could be minimized. Kinetic PCR assays were also applied to investigate the potential of pooled sample analysis. RESULTS: Our results show that small amounts of DNA can be successfully amplified in a high-throughput fashion using both kinetic PCR and molecular beacon methods. Greater than 97% of the genotype results from these two methods are consistent. In addition, error rates in allele frequency measurements using DNA pools of 100 or more samples were often less than 1% and usually less than 3%, which provides another option for substantially minimizing the costs of genotyping in studies involving large numbers of individuals. CONCLUSIONS: Effective assays have been designed for a spectrum of genes widely studied in birth defects, including: MTHFR, NAT1, TGFA, RFC1, PAX9, EPHX1, and SKI. An efficient assay has been designed for the detection of the presence of X and Y chromosomes, which can be applied to the studies of sex chromosome abnormalities or sample quality control.
Axially chiral thioamide ligands L5, L6, L8, L11, and bis(thioamide) ligand L13 were prepared from the reaction of (S)-(-)-1,1'-binaphthyl-2,2'-diamine with acyl chlorides and phosphorus pentasulfide (P2S5). The catalytic asymmetric 1,4-addition of diethylzinc to alpha,beta-unsaturated ketones was examined using this novel chiral ligand system with 28-73% ee in moderate to good yields.