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S Huang

Publications and source records attributed to S Huang.

At least 73 records · Page 4Linked to original sources
PubMed2001

Single step on-column frit making for capillary high-performance liquid chromatography using sol-gel technology.

One step frit-making in packing fused-silica capillary column of high-performance liquid chromatography was developed using sol-gel technology. Frit fabrication procedure was quite simple without sintering. On-column frit was formed through gelling of sol solution with packing materials, silica gel, and jointing the particles together with capillary wall through bonded and immobilized networks. Solvent types and proportions in sol solution were selected. And the sol solution compositions as well as amount of silica gel particles were also optimized to achieve maximum strength. Such an on-column frit of 250 microm in diameter is capable of resistant packing pressure up to 500 bars in ultra-sonic bath action. Chemical resistance to solvents and extreme pHs were also tested. Scanning electron micrograms of the frit profile showed that the evolving sol-gel network joined particles to each other and onto the column wall. Routine runs in reversed-phase mode, the frits of several columns proved to be effective enough to resist pressures without collapse.

Chromatography, High Pressure Liquid↗
PubMed2001

A 50-kDa membrane protein mediates sialic acid-independent binding and infection of conjunctival cells by adenovirus type 37.

The ocular tropism of adenovirus type 37 (Ad37) does not correlate with the wide distribution of the 46-kDa coxsackievirus and adenovirus receptor (CAR), the major receptor for most adenovirus serotypes. We previously found that Ad37 infects and binds well to conjunctival cells (Chang C), but poorly to lung epithelial (A549) cells that express CAR and hypothesized that this serotype uses a distinct receptor that is selectively expressed on conjunctival cells. To test this, we produced particles of a fiber-deleted Ad5 vector containing the Ad37 fiber protein. The "pseudotyped" vector infected Chang C cells better than A549 cells using a CAR-independent pathway. Ad37 binding was calcium-dependent and was abolished by protease digestion of cell surface proteins. Using a virus overlay protein blot assay (VOPBA), we detected calcium-dependent Ad37 binding to 50- and 60-kDa membrane proteins on permissive Chang C cells. In contrast, calcium-dependent binding was detected with only the 60-kDa protein on nonpermissive A549 cells. Ad19p, a closely related serotype that failed to bind to conjunctival cells, recognized the 60-kDa, but not the 50-kDa, protein. Ad37 has been reported to use sialic acid instead of CAR as a cell receptor on A549 cells. Pretreatment of Chang C cells with neuraminidase abolished Ad37 binding to only the 60-kDa protein, suggesting that sialic acid mediates Ad37 binding to the 60-kDa protein. The pseudotyped Ad37 vector was also able to infect neuraminidase-treated Chang C cells. Thus, subgroup D adenoviral binding to the 50-kDa protein is calcium-dependent and cell type- and serotype-specific, whereas binding to the 60-kDa protein is not necessary for infection of conjunctival cells. Together, these data suggest that the 50-kDa protein is the major receptor for Ad37 on conjunctival cells.

Adenoviruses, Human↗
PubMed2001

Bcl-2 and GDNF delivered by HSV-mediated gene transfer act additively to protect dopaminergic neurons from 6-OHDA-induced degeneration.

Previous studies have demonstrated that either the neurotrophin glial-derived neurotrophic factor (GDNF) or the antiapoptotic peptide Bcl-2 delivered into striatum by a viral vector protects dopaminergic neurons of the substantia nigra in vivo from degeneration induced by the administration of the neurotoxin 6-hydroxydopamine (6-OHDA). In this study we used recombinant, replication-incompetent, genomic herpes simplex virus-based vectors to deliver the genes coding for Bcl-2 and GDNF into rat substantia nigra (SN) 1 week prior to 6-OHDA injection into the striatum. Vector-mediated expression of either Bcl-2 or GDNF alone each resulted in a doubling in cell survival as measured by retrograde labeling with fluorogold (FG) and a 50% increase in tyrosine hydroxylase-immunoreactive (TH-IR) neurons in the lesioned SN compared to the unlesioned side. Gene transfer of Bcl-2 and GDNF were equivalent in this effect. Coadministration of the Bcl-2-expressing vector with the GDNF-expressing vector improved the survival of lesioned SN neurons as measured by FG labeling by 33% and by the expression of TH-IR by 15%. These results suggest that the two factors delivered together act in an additive fashion to improve DA cell survival in the face of 6-OHDA toxicity.

Animals↗
PubMed2001

Fluorescence microscopy of single viral capsids.

To build a foundation for the single-molecule fluorescence microscopy of protein complexes, the present study achieved fluorescence microscopy of single, nucleic acid-free protein capsids of bacteriophage T7. The capsids were stained with Alexa 488 (green emission). Manipulation of the capsids' thermal motion was achieved in three dimensions. The procedure for manipulation included embedding the capsids in an agarose gel. The data indicate that the thermal motion of capsids is reduced by the sieving of the gel. The thermal motion can be reduced to any desired level. A semilogarithmic plot of an effective diffusion constant as a function of gel concentration is linear. Single, diffusing T7 capsids were also visualized in the presence of single DNA molecules that had been both stretched and immobilized by gel-embedding. The DNA molecules were stained with ethidium (orange emission). This study shows that single-molecule (protein and DNA) analysis is possible for both packaging of DNA in a bacteriophage capsid and other events of DNA metabolism. The major problem is the maintenance of biochemical activity.

Bacteriophage T7↗
PubMed2001

The chicken RelB transcription factor has transactivation sequences and a tissue-specific expression pattern that are distinct from mammalian RelB.

Rel/NF-kappaB proteins are eukaryotic transcription factors that control the expression of genes involved in a large variety of cellular processes. Rel proteins share a highly conserved DNA-binding/dimerization domain called the Rel Homology (RH) domain. We have constructed and characterized a composite cDNA encoding most of the chicken RelB transcription factor. The predicted chicken RelB protein has a high degree of sequence similarity to other vertebrate RelB proteins within the RH domain, but is much less conserved outside this domain. Chicken RelB does not bind DNA as a homodimer, but forms DNA-binding heterodimers with NF-kappaB p50 or p52. Overexpressed chicken RelB localizes to the nucleus in chicken embryo fibroblasts, and the nonconserved C-terminal sequences of chicken RelB contain a transactivation domain that functions in chicken and mouse fibroblasts. Thus, chicken RelB has functional properties similar to other vertebrate RelB proteins. However, Western blotting of diverse chicken tissues indicates that chicken RelB is more widely expressed than mammalian RelB.

Active Transport, Cell Nucleus↗
PubMed2001

[Possibilities of broad spectrum analysis of gene expression patterns with cDNA arrays].

BACKGROUND: Our knowledge about the molecular and genomic background of diseases has expanded dramatically in the recent past and cDNA microarrays now provide the opportunity to simultaneously analyse the expression of thousands of genes. This could pave the way towards a systematic exploration of the pathogenetic principle of ophthalmological diseases which could lead to the identification of key disease-specific molecules that will be useful as diagnostic marker or serve as therapeutic targets. MATERIALS AND METHODS: Various strategies for cDNA microarray analysis are reviewed, including different commercially available arrays (microarrays on glass and arrays on nylon filters) as well as methods for analysing the unprecedented large amounts of data from a single experiment. Possible applications for research and clinical applications in ophthalmology are discussed. RESULTS: The cDNA microarray-based technology allows the rapid and cost-effective screening of gene expression without a priori knowledge about which gene might be of interest. Here, we discuss how the analysis of gene expression as whole profiles instead of the conventional focus on an individual gene may offer new insights into the fundamental nature of the pathogenesis of complex diseases using the example of early diabetic retinopathy. CONCLUSION: To date, the gene-array technology is still largely a laboratory procedure and has not yet been used in the clinical setting. However, in clinically oriented basic research, it will allow a more encompassing analysis of disease processes and thus lead to the identification of important diagnostic tools and potential drug targets in ophthalmological diseases.

Diabetic Retinopathy↗
PubMed2001

Fine genetic mapping and BAC contig development for the citrus tristeza virus resistance gene locus in Poncirus trifoliata (Raf.).

A map-based cloning strategy has been employed to isolate Ctv, a single dominant gene from Poncirus trifoliata that confers resistance to citrus tristeza virus (CTV), the most important viral pathogen of citrus. Cloning of this gene will allow development of commercially acceptable, virus-resistant cultivars. A high-resolution genetic linkage map of the Ctv locus region was developed using a backcross population of 678 individuals. Three DNA markers that were closely linked or co-segregated with Ctv were identified and used to screen BAC libraries derived from an intergeneric hybrid of Poncirus and Citrus. Through chromosome walking and landing, two BAC contigs were developed: one encompassing the Ctv region, and the other spanning the allelic susceptibility gene region. The resistance gene contig consists of 20 BAC clones and is approximately 550 kb in length; the susceptibility gene contig consists of 16 BAC clones and extends about 450 kb. The Ctv locus was localized within a genomic region of approximately 180 kb by genetic mapping of BAC insert ends. The BAC contigs were integrated with the genetic map; variation in the ratio of genetic to physical distance was observed in the vicinity of Ctv. Southern hybridization data indicated that a few copies of NBS-LRR class sequences are distributed at or around the Ctv locus. Efforts are being made to assign the Ctv locus to a smaller genomic fragment whose function can be confirmed through genetic complementation of a CTV susceptible phenotype. These results indicate that map-based gene cloning is feasible in a woody perennial.

Blotting, Southern↗
PubMed2001

Multiple leiomyomas of the esophagus, lung, and uterus in multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disorder characterized by multiple parathyroid, pancreatic, duodenal, and pituitary neuroendocrine tumors. Nonendocrine mesenchymal tumors, such as lipomas, collagenomas, and angiofibromas have also been reported. MEN1-associated neuroendocrine and some mesenchymal tumors have documented MEN1 gene alterations on chromosome 11q13. To test whether the MEN1 gene is involved in the pathogenesis of multiple smooth muscle tumors, we examined the 11q13 loss of heterozygosity (LOH) and clonality patterns in 15 leiomyomata of the esophagus, lung, and uterus from five patients with MEN1. Forty sporadic uterine leiomyomata were also studied for 11q13 LOH. LOH analysis was performed using four polymorphic DNA markers at the MEN1 gene locus; D11S480, PYGM, D11S449, and INT-2. 11q13 LOH was detected in 10 of 12 (83%) MEN1-associated esophageal and uterine smooth muscle tumors. In contrast, LOH at the MEN1 gene locus was demonstrated only in 2 of 40 (5%) sporadic uterine tumors. LOH at 11q13 was not documented in three lung smooth muscle tumors from a single patient with MEN1. Ten tumors from two female patients were additionally assessed for clonality by X-chromosome inactivation analysis. The results demonstrated different clonality patterns in multiple tumors in the same organ in each individual patient. The data indicate that leiomyomata of the esophagus and uterus in MEN1 patients arise as independent clones, develop through MEN1 gene alterations, and are an integral part of MEN1. However, the MEN1 gene is not a significant contributor to the tumorigenesis of sporadic uterine leiomyomata.

Adult↗
PubMed2001

Fluoride concentrations at and near the neonatal line in human deciduous tooth enamel obtained from a naturally fluoridated and a non-fluoridated area.

This study sought to obtain a precise profile of fluoride concentrations at and near the neonatal line in deciduous incisors and canines from the naturally fluoridated area (1.0--1.3 parts/10(6) F in drinking water) of West Hartlepool and the non-fluoridated area (less than 0.1 parts/10(6) F in drinking water) of Leeds in England. An abrasive microsampling method was used to determine the distribution of fluoride and phosphorus concentrations. The profile of fluoride concentrations in 100-microm layers before and after the neonatal line, that is, in the prenatal and postnatal enamel, were significantly higher in teeth from the fluoridated than non-fluoridated areas. It was concluded that the fact that the fluoride concentrations were about the same prenatally and postnatally in deciduous enamel obtained from the fluoridated and non-fluoridated areas indicates that fluoride enters the prenatal deciduous enamel and that it is transferred through the placenta.

Calcium↗
PubMed2001

The studies of hemoglobinopathies and thalassemia in China--the experiences in Shanghai Institute of Medical Genetics.

BACKGROUND: In the past two decades, a large-scale survey of hemoglobinopathies and thalassemia was carried out in mainland China, involving nearly one million people in 28 provinces. The incidences of hemoglobin (Hb) variants, alpha-thalassemia and beta-thalassemia were 0.33%, 2.64% and 0.66%, respectively. The chemical structural analysis identified 67 Hb variants. Among them, 20 are new variants. The analysis of the alpha-globin gene organization in 111 HbH patients showed 76 cases (68.5%) were of the deletion type, 8 had Hb Constant Spring and the other cases were of non-deletion type. The results of the molecular characterization of more than 200 beta-thalassemia alleles showed that the most common types of beta-thalassemia mutations in China are CD 41/42 (-4 bp), IVS-II-nt.654 C-->T, CD 17 A-->T, CD 71/72 (+A) and -28 A-->G. METHODS: To explore the simple method for molecular diagnosis of beta-thalassemia, multiplex allele-specific amplification (MAS-PCR) was used that could simultaneously detect the above five common types of beta-thalassemia mutations. RESULTS: Based on the molecular analysis of beta-thalassemia intermedia, beta-thalassemia homozygotes or compound heterozygotes combined with alpha-thalassemia, as well as the conjunctive abnormalities of beta-thalassemia heterozygote with triplicated haplotype of alpha-globin genes, were the most common cause of thalassemia intermedia in China. We also used the RT-PCR quantitation method to show that the most common beta-thalassemia allele, IVS-II-nt.654 C-->T, still produced a small amount (about 15%) of normally spliced beta-globin mRNA, therefore, causing beta+-thalassemia. In clinical trials of hydroxyurea (HU) treatment for beta-thalassemia patients, we found that HU may enhance the expression of the beta-globin gene in some patients, leading to an alleviation of clinical symptoms. In the studies of the reversal of aberrant splicing of IVS-II-nt.654 C-->T allele by the antisense approach, we constructed a mammalian expression vector that can produce an antisense RNA targeting against the aberrant splice sites of IVS-II-nt.654 C-->T pre-mRNA. CONCLUSIONS: The results indicated that the antisense RNA produced from the vector could efficiently suppress the aberrant splicing pattern and restore the correct splicing pathway in vitro and in vivo, leading to the improvement of globin chain biosynthesis in thalassemia cells.

China↗
PubMed2001

Study on the kinetics of cerium(III) adsorption-desorption on different soils of China.

The kinetics of Ce(III) adsorption-desorption on four typical soils in China has been studied by using the batch method with the radioactive nuclide 141Ce. Results indicated that Ce(III) adsorption was rapid and nearly finished in less than 0.5 min. Desorption procedure was about completed in 1-30 min in the tested soils. Ce(III) desorption equilibrium times vary with different soils. The amounts of Ce(III) desorption on different soils in the same time were different. The Elovich equation proved to be the best models for fitting the data of Ce(III) desorption reactions in fluvo-aquic soil and black soil; and the parabolic-diffusion equation was the best model in red earth and loess soil.

Adsorption↗
PubMed2001

Resistance to rapamycin: a novel anticancer drug.

The macrocyclic lactone rapamycin has an established place as an immune suppressive agent in organ transplantation. However, more recently it has been recognized as an inhibitor of pathways that may be activated during malignant transformation and tumor progression. Thus, increasing interest is being directed to this class of antibiotic as potential antitumor agents. Here we summarize the history, mechanism of action, and mechanisms of resistance to rapamycin.

Animals↗
PubMed2001

Synchronization of separation and determination based on multichannel mode-filtered light detection with capillary electrophoresis.

A novel method for the synchronization of separation and determination is described, in which a mode-filtered light detector is used as an online detector in capillary electrophoresis. An instrument is described which has been developed for this purpose. The round capillary used in conventional capillary electrophoresis is replaced by an annular column, which is constructed from a naked optical fibre inserted into a fused-silica capillary. In fact, the annular electrophoresis column itself forms part of the mode-filtered light sensor. Along the side of the annular column are several detection channels for gathering and transmitting the mode-filtered light to a charge-coupled device (CCD). Every channel provides information on the sample from the point at which it is located. Using capillary isotachophoresis incorporating the annular column, the analytes in a sample containing alanine (10.0 mM) and glycine (9.7 mM) were simultaneously separated and determined using multichannel mode-filtered light detection with a detection limit of 1.5 mM.

Journal Article↗
PubMed2001

Organelle DNA phylogeography of Cycas taitungensis, a relict species in Taiwan.

The phylogegraphic pattern of Cycas taitungensis, an endemic species with two remaining populations in Taiwan, was investigated based on genetic variability and phylogeny of the atpB-rbcL noncoding spacer of chloroplast DNA (cpDNA) and the ribosomal DNA (rDNA) internal transcribed spacer (ITS) of mitochondrial DNA (mtDNA). High levels of genetic variation at both organelle loci, due to frequent intramolecular recombination, and low levels of genetic differentiation were detected in the relict gymnosperm. The apportionment of genetic variation within and between populations agreed with a migrant-pool model, which describes a migratory pattern with colonists recruited from a random sample of earlier existing populations. Phylogenies obtained from cpDNA and mtDNA were discordant according to neighbour-joining analyses. In total four chlorotypes (clades I-IV) and five mitotypes (clades A-E) were identified based on minimum spanning networks of each locus. Significant linkage disequilibrium in mitotype-chlorotype associations excluded the possibility of the recurrent homoplasious mutations as the major force causing phylogenetic inconsistency. The most abundant chlorotype I was associated with all mitotypes and the most abundant mitotype C with all chlorotypes; no combinations of rare mitotypes with rare chlorotypes were found. According to nested clade analyses, such nonrandom associations may be ascribed to relative ages among alleles associated with the geological history through which cycads evolved. Nested in networks as interior nodes coupled with wide geographical distribution, the most dominant cytotypes of CI and EI may represent ancestral haplotypes of C. taitungensis with a possible long existence prior to the Pleistocene glacial maximum. In contrast, rare chlorotypes and mitotypes with restricted and patchy distribution may have relatively recent origins. Newly evolved genetic elements of mtDNA, with a low frequency, were likely to be associated with the dominant chlorotype, and vice versa, resulting in the nonrandom mitotype-chlorotype associations. Paraphyly of CI and EI cytotypes, leading to the low level of genetic differentiation between cycad populations, indicated a short period for isolation, which allowed low possibilities of the attainment of coalescence at polymorphic ancestral alleles.

Cycas↗
PubMed2001

Phylogeography of Kandelia candel in East Asiatic mangroves based on nucleotide variation of chloroplast and mitochondrial DNAs.

Vivipary with precocious seedlings in mangrove plants was thought to be a hindrance to long-range dispersal. To examine the extent of seedling dispersal across oceans, we investigated the phylogeny and genetic structure among East Asiatic populations of Kandelia candel based on organelle DNAs. In total, three, 28 and seven haplotypes of the chloroplast DNA (cpDNA) atpB-rbcL spacer, cpDNA trnL-trnF spacer, and mitochondrial DNA (mtDNA) internal transcribed spacer (ITS) were identified, respectively, from 202 individuals. Three data sets suggested consistent phylogenies recovering two differentiated lineages corresponding to geographical regions, i.e. northern South-China-Sea + East-China-Sea region and southern South-China-Sea region (Sarawak). Phylogenetically, the Sarawak population was closely related to the Ranong population of western Peninsula Malaysia instead of other South-China-Sea populations, indicating its possible origin from the Indian Ocean Rim. No geographical subdivision was detected within the northern geographical region. An analysis of molecular variance (AMOVA) revealed low levels of genetic differentiation between and within mainland and island populations (phiCT = 0.015, phiSC = 0.037), indicating conspicuous long-distance seedling dispersal across oceans. Significant linkage disequilibrium excluded the possibility of recurrent homoplasious mutations as the major force causing phylogenetic discrepancy between mtDNA and the trnL-trnF spacer within the northern region. Instead, relative ages of alleles contributed to non-random chlorotype-mitotype associations and tree inconsistency. Widespread distribution and random associations (chi2 = 0.822, P = 0.189) of eight hypothetical ancestral cytotypes indicated the panmixis of populations of the northern geographical region as a whole. In contrast, rare and recently evolved alleles were restricted to marginal populations, revealing some preferential directional migration.

Alleles↗
PubMed2001

Reassignment of the EPB4.1 gene to 1p36 and assessment of its involvement in neuroblastomas.

OBJECTIVES: EPB4.1 has been previously mapped to human chromosome 1p33-p34.2. In contradiction to this chromosomal location, we have mapped EPB4.1-1p36 by using fluorescence in situ hybridization and radiation hybrid mapping. In neuroblastomas, deletions of the telomeric end of chromosome 1 (1p36) are the most common genetic aberration. METHODS: We investigated whether genetic aberrations of EPB4.1 can be detected in some neuroblastomas by analyzing 72 tumours for EPB4.1 mutation, expression, and alternative splicing pattern. Furthermore, EPB4.1 protein from a neuroblastoma cell line was studied for its subcellular localization. RESULTS: Sequence changes could be detected in 14 out of 72 neuroblastomas, including missense, silent, and intronic changes. Duplex RT-PCR analysis revealed a subset of 11 tumours expressing significantly low levels of EPB4.1. Significant EPB4.1 sequence changes that were detected included an exon 4 G/A missense mutation (amino acid: V/I) that was shown to be associated with absence of wild-type EPB4.1 expression (3 tumours), an exon 8 G/A missense mutation (V/M) (1 tumour), and an intronic sequence change that was shown to be associated with the presence of an aberrant transcript (1 tumour). Splicing pattern analysis revealed that all EPB4.1 transcripts from tumours exclude exon 3, a splicing pattern for generating the 135 kDa isoform. EPB4.1 cDNA cloned from a neuroblastoma cell line produced a 135-kDa protein with a cytoplasm/membrane localization. CONCLUSIONS: Out of 72 neuroblastomas we have identified 11 tumours with impaired EPB4.1 expression and 5 tumours with significant sequence changes. We also found that the 135 kDa isoform is the main EPB4.1 product in neuroblastoma. EPB4.1 cDNA from a neuroblastoma cell line produced a 135-kDa protein and displayed a cytoplasm/membrane localization in transfected cells.

Alternative Splicing↗