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S Zhu

Publications and source records attributed to S Zhu.

At least 37 records · Page 2Linked to original sources
PubMed2005

Phylogenetic distribution, functional epitopes and evolution of the CSalphabeta superfamily.

A superfamily of proteins often conserves a common structural scaffold but develops diverse biochemical and biological functions during evolution. The understanding of evolutionary mechanisms responsible for this diversity is of fundamental importance not only in structural genomics but also in nature-guided drug design. A superfamily of peptides with a conserved CSalphabeta structural motif provides a considerably intriguing example to approach such an issue. The peptides from this superfamily have wide origins, ranging from plants to animals, and exhibit diverse biological activities, varying from a sweet-tasting protein to antibacterial defensins and animal toxins targeting ion channels. This review describes the phylogenetic distribution and structural classifi cation of this unique scaffold and provides new insights into its functional diversity from the perspective of sequence, structure and evolution.

Amino Acid Motifs↗
PubMed2005

In vitro expanded human CD4+CD25+ regulatory T cells suppress effector T cell proliferation.

Regulatory T cells (Tregs) have been shown to be critical in the balance between autoimmunity and tolerance and have been implicated in several human autoimmune diseases. However, the small number of Tregs in peripheral blood limits their therapeutic potential. Therefore, we developed a protocol that would allow for the expansion of Tregs while retaining their suppressive activity. We isolated CD4+CD25 hi cells from human peripheral blood and expanded them in vitro in the presence of anti-CD3 and anti-CD28 magnetic Xcyte Dynabeads and high concentrations of exogenous Interleukin (IL)-2. Tregs were effectively expanded up to 200-fold while maintaining surface expression of CD25 and other markers of Tregs: CD62L, HLA-DR, CCR6, and FOXP3. The expanded Tregs suppressed proliferation and cytokine secretion of responder PBMCs in co-cultures stimulated with anti-CD3 or alloantigen. Treg expansion is a critical first step before consideration of Tregs as a therapeutic intervention in patients with autoimmune or graft-versus-host disease.

Autoimmune Diseases↗
PubMed2005

Co-combustion performance of poultry wastes and natural gas in the advanced Swirling Fluidized Bed Combustor (SFBC).

Co-combustion of poultry wastes with natural gas in an advanced Swirling Fluidized Bed Combustor (SFBC) has been carried out to investigate the performance of poultry wastes combustion. Wastes burnt were poultry litter, poultry manure and sawdust. This paper presents the effect of three different wastes, excess air ratio, and secondary/total air ratio on the combustion characteristics. These characteristics include temperature distributions, carbon combustion efficiency, major gaseous pollutants emissions and heat recovery efficiency. The results indicate that, with the given moisture and ash contents in wastes, the excess air and the secondary air play important roles in achieving stable combustion. The carbon combustion efficiency could increase by 8-10% when the excess air is increased to 25% with the secondary air being at 20% and having a low injection height. However, the carbon combustion efficiency for the sawdust, which is 92% on average, is much higher than that of the poultry litter and manure, which is 81% and 76% on average, respectively. Differences regarding temperature distribution and pollutants emission were also observed with different combinations of the excess air, the secondary air and the secondary air injection height. The NO(x) emission was very low even though the materials contain high levels of nitrogen. In addition, the heat recovery efficiency aiming at the commercial use of the SFBC system for the farm industries was also evaluated.

Agriculture↗
PubMed2004

Mechanisms by which resistant starches and non-starch polysaccharide sources affect the metabolism and disposition of the food carcinogen, 2-amino-3-methylimidazo[4,5-f]quinoline.

Although both non-starch polysaccharides (NSP) and resistant starches (RS) are included in current definitions of dietary fibre, our previous work has suggested fundamental differences in the way in which these two classes of material affect the disposition and absorption of a dietary carcinogen. The present studies explore whether different effects on carcinogen metabolism could play a role in the contrasting patterns seen previously. Groups of female Wistar rats were pre-fed for 4 weeks one of five types of defined diet (AIN-76). The control diet contained 35% maize starch and no dietary fibre. The RS-containing diets had all the maize starch substituted with either Hi-maize or potato starch. In the NSP-containing diets, 10% of the maize starch was substituted with dietary fibre in the form of either lignified plant cell walls (wheat straw) or soluble dietary fibre (apple pectin). Pre-fed rats were gavaged with the food carcinogen, [2-14C] 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and plasma and urinary metabolites characterized using HPLC at various time intervals after administration. After 4 h gavage, plasma from rats on both RS-containing diets contained significantly higher levels of intact IQ and lower levels of the major metabolites, IQ-5-O-glucuronide and IQ-5-sulfate, as compared with plasma from the negative control group at this time. In contrast, plasma from animals on the NSP-containing wheat straw diet (and to a lesser extent the apple pectin diet) showed significantly lower levels of intact IQ, and significantly higher levels of the two major metabolites, as compared with those from the control rats. These different metabolite profiles were also reflected in different urinary excretion profiles. Urine from rats pre-fed RS-containing diets revealed significantly slower metabolite excretion as compared with urine from rats that had been given the NSP-containing diets. Western blotting methodologies also profiled differences between the effects of these two types of dietary fibre in the expression of xenobiotic metabolizing enzymes. We conclude that changes in activity and expression of xenobiotic metabolising enzymes could play a role in the contrasting effects of these two types of dietary fibre on carcinogen uptake and disposition.

Animals↗
PubMed2004

The scorpine family of defensins: gene structure, alternative polyadenylation and fold recognition.

Small cationic antimicrobial peptides (SCAMPs) as effectors of animal innate immunity provide the first defense against infectious pathogens. This class of molecules exists widely in invertebrate hemolymph and vertebrate skin secretion, but animal venoms are emerging as a new rich resource. Scorpine is a unique scorpion venom defensin peptide that has an extended amino-terminal sequence similar to cecropins. From the African scorpion Opistophthalmus carinatus venom gland, we isolated and identified several cDNAs encoding four new homologs of scorpine (named opiscorpines 1-4). Importantly, we show for the first time the existence of multiple opiscorpine mRNAs with variable 3' untranslated regions (UTRs) in the venom gland, which may be generated by alternative usage of polyadenylation signals. The complete opiscorpine gene structure including its promoter region is determined by genomic DNA amplification. Two large introns were found to be located within the 5' UTR and at the boundary of the mature peptide-coding region. Such a gene structure is distinct, when compared with other scorpion venom peptide genes. However, a comparative promoter analysis revealed that both opiscorpine and scorpion venom neurotoxins share a similar promoter organization. Sequence analysis and structural modeling allow us to group the scorpines and scorpion long-chain K-channel toxins together into one family that shares a similar fold with two distinct domains. The N-terminal cecropin-like domain displaying a clear antimicrobial activity implies that the scorpine family represents a group of real naturally occurring hybrids. Based on the phylogenetic analysis, a possible cooperative interaction between the N and C domains is elucidated, which provides an evolutionary basis for the design of a new class of anti-infectious drugs.

Amino Acid Sequence↗
PubMed2003

A composite chiral pair of rotational bands in the odd-A nucleus 135Nd.

High-spin states in 135Nd were populated with the 110Pd(30Si,5n)135Nd reaction at a 30Si bombarding energy of 133 MeV. Two DeltaI=1 bands with close excitation energies and the same parity were observed. These bands are directly linked by DeltaI=1 and DeltaI=2 transitions. The chiral nature of these two bands is confirmed by comparison with three-dimensional tilted axis cranking calculations. This is the first observation of a three-quasiparticle chiral structure and establishes the primarily geometric nature of this phenomenon.

Journal Article↗
PubMed2003

A genetic linkage map for hexaploid, cultivated oat (Avena sativa L.) based on an intraspecific cross 'Ogle/MAM17-5'.

Genetic research and breeding of oat ( Avena sativa L.) would be aided by development of a genetic linkage map for a breeding population. Such a map could be used for localization of qualitative and quantitative trait loci, marker-assisted selection and other genetic analysis in an adapted, agronomically useful background. The objectives of this research were to develop a genetic linkage map of hexaploid cultivated oat, to identify homoeologous relationships of linkage groups, and to compare homologous linkage groups between this map and the previously published hexaploid oat map from the cross 'Kanota/Ogle' (KO). A total of 510 markers, including 172 restriction fragment length polymorphisms (RFLP), 324 amplified fragment length polymorphisms (AFLP) and 14 simple sequence repeats (SSR), were assessed on a recombinant inbred population of 152 F(5:6) lines derived from the cross, 'Ogle/MAM17-5' (OM). Twenty eight linkage groups of 5 cM or longer were formed using 476 of the markers, while 34 markers remained either unlinked or in small fragments less than 5 cM. The 28 linkage groups contained from 3 to 33 markers, and varied in size from 5.2 to 123.0 cM, representing a total map length of 1,396.7 cM. Three putative homoeologous groups (OM7, OM8 and OM18; OM2 and OM23; OM13 and OM16) were identified. Comparison with the published KO map indicated that nine OM linkage groups could be determined to be homologous to linkage groups in the KO map. Further comparison of the homologous linkage groups revealed that residual differences in genomic rearrangements existed between the two hexaploid oat populations. Some linkage groups were significantly extended compared with the KO map. Since the OM mapping population is segregating for a number of agronomically important traits, this genetic map will provide a useful tool for identification of qualitative and quantitative loci for these traits.

Avena↗
PubMed2003

Molecular mapping of genomic regions underlying barley yellow dwarf tolerance in cultivated oat (Avena sativa L.).

Barley yellow dwarf (BYD) is one of the most important viral diseases in small grains, including oat (Avena sativa L.). Breeding for BYD tolerance is an effective and efficient means to control the disease. Characterization of major sources of tolerance, and identification of marker and the trait associations, will directly benefit breeding for BYD tolerance. Genomic regions underlying BYD tolerance were mapped and characterized in an oat population consisting of 152 recombinant inbred lines from the cross of 'Ogle' (tolerant)/MAM17-5 (sensitive). Tolerance was evaluated in replicated field trials across 2 years under artificial inoculation with viruliferous aphids harboring BYD virus isolate PAV-IL. Composite interval mapping was used for quantitative trait loci (QTLs) analysis with a framework map consisting of 272 molecular markers. Four QTLs, BYDq1, BYDq2, BYDq3 and BYDq4, for BYD tolerance were identified on linkage groups OM1, 5, 7 and 24, respectively. All but BYDq2 were consistently detected across both years. Significant epistasis was found between some QTLs. The final model including the epistatic effect explained 50.3 to 58.2% of the total phenotypic variation for BYD tolerance. Some QTLs for BYD tolerance were closely linked to QTLs for plant height and days to heading. Potential problems with QTL mapping for BYD tolerance have been discussed. The identified association of markers and tolerance should be useful to pyramid favorable alleles for BYD tolerance into individual oat lines.

Adaptation, Physiological↗
PubMed2003

Association between weight fluctuation and fasting insulin concentration in Japanese men.

OBJECTIVE: To investigate whether long-term weight fluctuation is associated with the fasting serum insulin concentration. DESIGN AND SUBJECTS: Weight histories of 1932 male Japanese workers aged 40-59 y were analyzed in relation to their current fasting serum insulin concentration. MEASUREMENTS: Individual weight fluctuation was calculated by root mean square error (RMSE) along the linear regression line of weight measured at five to six different ages. RESULTS: The mean RMSE and fasting insulin concentration were 1.22 kg and 4.5 microU/ml, respectively. The multivariate adjusted insulin level became higher with the increase in weight fluctuation. Subanalysis stratified by current body mass index (BMI) showed that the multivariate adjusted insulin level in individuals in the top quartile of fluctuation was 4.3 microU/ml, against 3.9 microU/ml in those in the bottom quartile (P=0.018, analysis of covariance (ANCOVA)) in the normal weight subgroup with current BMI below 25 kg/m(2). In the overweight subgroup with BMI 25 kg/m(2) or above, the level was 6.9 microU/ml in individuals in the top quartile and 6.2 microU/ml in those in the bottom quartile (P=0.054, ANCOVA). CONCLUSION: The results suggest that weight fluctuation increases the risk of developing hyperinsulinemia. Prospective observations together with measurement of changes in adiposity are needed for confirmation.

Adult↗
PubMed2003

The metabolic syndrome is associated with elevated circulating C-reactive protein in healthy reference range, a systemic low-grade inflammatory state.

OBJECTIVE: To elucidate the underlying mechanisms between C-reactive protein (CRP) and cardiovascular disease, we examined the association of circulating CRP in healthy reference range (< or =1.0 mg/dl) measured by high-sensitive CRP assay with the metabolic syndrome (MS). DESIGN: Cross-sectional study of circulating CRP in adult men. SUBJECTS: A total of 3692 Japanese men aged 34-69 y. MEASUREMENTS: Serum CRP, total cholesterol, triglycerides, LDL-cholesterol, fasting glucose, fasting insulin, uric acid, systolic blood pressure, diastolic blood pressure, and body mass index (BMI). RESULTS: There was a statistically significant positive correlation between CRP and BMI (r=0.25), total cholesterol (r=0.096), triglycerides (r=0.22), LDL-cholesterol (r=0.12), fasting glucose (r=0.088), fasting insulin (r=0.17), uric acid (r=0.13), systolic blood pressure (r=0.12), and diastolic blood pressure (r=0.11), and a significant negative correlation of CRP with HDL-cholesterol (r=0.24). After adjusting for age, smoking, and all other components of MS, obesity, hypertriglyceridemia, hyper-LDL-cholesterolemia, diabetes, hyperinsulinemia, and hyperuricemia were significantly associated with both mildly (> or =0.06 mg/dl) and moderately (> or =0.11 mg/dl) elevated CRP. Compared with men who had no such components of the MS, those who had one, two, three, four, and five or more components were, respectively, 1.48, 1.84, 1.92, 3.42, and 4.17 times more likely to have mildly elevated CRP levels (trend P<0.001). As for moderately elevated CRP, the same association was observed. CONCLUSIONS: These results indicate that a variety of components of the MS are associated with elevated CRP levels in a systemic low-grade inflammatory state.

Adult↗
PubMed2003

Long-term body weight variability is associated with elevated C-reactive protein independent of current body mass index among Japanese men.

OBJECTIVE: To elucidate the effect of long-term weight variability on C-reactive protein (CRP) levels. DESIGN: Cross-sectional study of the circulating CRP. SUBJECTS: A total of 637 Japanese men aged 40-49 y in1997. MEASUREMENTS: Serum CRP levels, body mass index in 1997 (current BMI), the slope of weight on age (weight-slope) representing an individual's weight trend of direction and magnitude, and the root mean square error around the slope of weight on age (weight-RMSE) representing the weight fluctuation magnitude, as calculated by a simple linear regression model in which each value of the subject's five actual weights (aged 20, 25, 30 y, five years ago, and current) was a dependent variable and the subject's ages independent variables. RESULTS: After adjustment for age and confounders, including smoking and health status, the odds ratios of elevated CRP (> or =0.06 mg/dl) were 1.83 (95% CI: 1.25-2.69), 2.63 (1.69-4.11), and 10.31 (2.17-48.98) for upper normal-weight (BMI: 22-<25 kg/m(2)), overweight (25-<30), and obese (> or =30) persons, respectively, compared with lower normal-weight persons (18.5-<22). Adjusting for age, confounders, and current BMI, weight-slope was positively associated with CRP level especially among subjects with BMI> or =25 kg/m(2) (trend P<0.01), and weight-RMSE was positively associated with CRP level particularly among subjects with BMI <25 kg/m(2) (trend P<0.05). CONCLUSION: Our results suggest a state of low-grade systemic inflammation not only in overweight and obese persons, but also in normal-weight persons with large weight fluctuation, possibly explaining in part the positive association between weight fluctuation and CVD.

Adipose Tissue↗
PubMed2002

Models for improving cataract surgical rates in southern China.

BACKGROUND/AIMS: Unoperated cataract is the main challenge to blindness reduction in China. This demonstration project in Guangdong Province was designed to test various strategies to improve the cataract surgical rate. METHODS: Two strategies (reduction of the cataract surgical fee and training of country doctors in the detection of cataract blindness) were implemented in each of two counties. Both interventions were introduced in a third county. RESULTS: The cataract surgery rate (CSR) per million was 366 in the county where training took place, 588 where the fee was lowered, and 1140 where both interventions took place. The improvement in CSR was highly significant (p<0.001). CONCLUSIONS: In southern China, CSR can be increased with community based measures. Sustainability for such measures will be the major future challenge.

Aged↗
PubMed2001

Directed evolution of alpha-aspartyl dipeptidase from Salmonella typhimurium.

Model-free approaches (error-prone PCR to introduce random mutations, DNA shuffling to combine positive mutations, and screening of the resultant mutant libraries) have been used to enhance the catalytic activity and thermostability of alpha-aspartyl dipeptidase from Salmonella typhimurium, which is uniquely able to hydrolyze Asp-X dipeptides (where X is any amino acid) and one tripeptide (Asp-Gly-Gly). Under double selective pressures of activity and thermostability, through two rounds of error-prone PCR and three sequential generations of DNA shuffling, coupled with screening, a mutant pepEM3074 with approximately 47-fold increased enzyme activity compared with its wild-type parent was obtained. Moreover, the stability of pepEM3074 is increased significantly. Three amino acid substitutions (Asn89His, Gln153Glu, and Leu205Arg), two of them are near the active site and substrate binding pocket, were identified by sequencing the genes encoding this evolved enzyme. The mechanism of the enhancement of activity and stability was analyzed in this paper.

Amino Acid Substitution↗
PubMed2001

A naturally occurring non-coding fusion transcript derived from scorpion venom gland: implication for the regulation of scorpion toxin gene expression.

Scorpion venom glands synthesize and secrete a great number of low molecular mass toxic peptides for prey and defense. Many cDNAs and genomic genes encoding these toxins have been isolated and sequenced. However, their expression regulation mechanism is not yet known at present. During screening of a cDNA library prepared from venom glands of the scorpion Buthus martensii Karsch, we isolated a natural fusion cDNA composed of the 5'-untranslated region (UTR) and upstream coding sequence of a long-chain toxin transcript and the downstream coding sequence and 3'-UTR of a short-chain toxin transcript. The junction site is just the overlapping region of 11 nucleotides (GGCAAGGAAAT) between the two wild transcripts, and thus leads to the formation of an early stop codon, which will cause premature translation. Based on the above observations, combined with the genomic data, we proposed a characteristic regulation mechanism of scorpion toxin genes, in which trans-splicing and nonsense mediated mRNA decay are involved.

3' Untranslated Regions↗
PubMed2001

[Construction of attenuated Salmonella typhimurium vaccine strain expressing Helicobacter pylori catalase and observation on its protective immunity].

OBJECTIVE: To investigated the effect of attenuated Salmonella typhimurium vaccine strain expressing Helicobacter pylori (Hp) catalase (KatA) on protection against Hp infection. METHODS: Recombinant plasmid expressing KatA was constructed. Expression of KatA was induced with IPTG, and analyzed by SDS-PAGE and Western blot. The recombinant plasmid were introduced into attenuated Salmonella typhimurium SL3261 strain to construct live oral vaccine strain. C57BL/6 mice was orally immunized with this vaccine strain and then given orogastric challenge with live Hp Sydney strain. The stomach samples were submitted to a rapid urease test and quantitative culture. RESULTS: The SDS-PAGE showed a dominant additional protein with molecular weight of 79kDa which could specially react with antibody against GST and accounted for 19% of total bacteria proteins. Animal experiment indicated that this vaccine strain could protect mice against Hp infection. CONCLUSION: Attenuated Salmonella typhimurium vaccine strain expressing KatA could induce effective immune response in protection against Hp infection,which may play an important role in preventing and treating Hp infection and related diseases.

Administration, Oral↗