Biomedical subjects

J F Cheng

Publications and source records attributed to J F Cheng.

At least 37 records · Page 2Linked to original sources

PubMed1997

Dermal eosinophils in atopic dermatitis undergo cytolytic degeneration.

BACKGROUND: Immunofluorescent staining for eosinophil granule proteins in lesional skin of patients with atopic dermatitis shows extensive extracellular deposition throughout the upper dermis with relatively few intact eosinophils. OBJECTIVE: This study was carried out to determine whether eosinophil granule protein deposition in atopic dermatitis occurs by classical exocytosis, by piecemeal degranulation, or as a result of cytolysis. METHODS: Skin biopsy specimens from 10 patients with atopic dermatitis were examined by electron microscopy. RESULTS: The biopsy specimens showed varying degrees of dermal eosinophil granule major basic protein deposition by indirect immunofluorescence. Specimens from seven patients showed striking alterations of eosinophils by electron microscopy including intact eosinophils with granule alterations (reversal of core staining and/or core lucency) and with uropod processes. Biopsy specimens from six patients showed evidence of eosinophil degeneration with disruption of nuclear and/or plasma membranes. In four patients' specimens, membrane-bound eosinophil granules were present near degenerating eosinophils or were present in the absence of recognizable eosinophils. Evidence of classical exocytotic degranulation was not observed. Two of the specimens were also examined by immunoelectron microscopy for major basic protein localization. In these, major basic protein appeared to be lost from the granule core and distributed in the eosinophil cytoplasm as granules disintegrated and the cell disrupted. CONCLUSION: These findings support the hypothesis that eosinophils undergo cytolysis with release of granule contents and membrane-bound granules; this is likely the usual mechanism of eosinophil granule protein release in atopic dermatitis.

Adult↗

PubMed1997

Functional screening of 2 Mb of human chromosome 21q22.2 in transgenic mice implicates minibrain in learning defects associated with Down syndrome.

Using Down syndrome as a model for complex trait analysis, we sought to identify loci from chromosome 21q22.2 which, when present in an extra dose, contribute to learning abnormalities. We generated low-copy-number transgenic mice, containing four different yeast artificial chromosomes (YACs) that together cover approximately 2 megabases (Mb) of contiguous DNA from 21q22.2. We subjected independent lines derived from each of these YAC transgenes to a series of behavioural and learning assays. Two of the four YACs caused defects in learning and memory in the transgenic animals, while the other two YACs had no effect. The most severe defects were caused by a 570-kb YAC; the interval responsible for these defects was narrowed to a 180-kb critical region as a consequence of YAC fragmentation. This region contains the human homologue of a Drosophila gene, minibrain, and strongly implicates it in learning defects associated with Down syndrome.

Animals↗

PubMed1997

Computational and biological analysis of 680 kb of DNA sequence from the human 5q31 cytokine gene cluster region.

With the human genome project advancing into what will be a 7- to 10-year DNA sequencing phase, we are presented with the challenge of developing strategies to convert genomic sequence data, as they become available, into biologically meaningful information. We have analyzed 680 kb of noncontiguous DNA sequence from a 1-Mb region of human chromosome 5q31, coupling computational analysis with gene expression studies of tissues isolated from humans as well as from mice containing human YAC transgenes. This genomic interval has been noted previously for containing the cytokine gene cluster and a quantitative trait locus associated with inflammatory diseases. Our analysis identified and verified expression of 16 new genes, as well as 7 previously known genes. Of the total of 23 genes in this region, 78% had similarity matches to sequences in protein databases and 83% had exact expressed sequence tag (EST) database matches. Comparative mapping studies of eight of the new human genes discovered in the 5q31 region revealed that all are located in the syntenic region of mouse chromosome 11q. Our analysis demonstrates an approach for examining human sequence as it is made available from large sequencing programs and has resulted in the discovery of several biomedically important genes, including a cyclin, a transcription factor that is homologous to an oncogene, a protein involved in DNA repair, and several new members of a family of transporter proteins.

Animals↗

PubMed1996

Identification and analysis of the human and murine putative chromatin structure regulator SUPT6H and Supt6h.

We have isolated and sequenced SUPT6H and Supt6h, the human and murine homologues of the Saccharomyces cerevisiae and Caenorhabditis elegans genes SPT6 (P using 1603 aa = 6.7 e-95) and emb-5 (P using 1603 aa = 7.0 e-288), respectively. The human and murine SPT6 homologues are virtually identical, as they share >98% identity and >99% similarity at the protein level. The derived amino acid sequences of these two genes predict a 1603-aa protein (human) and a 1726-bp protein (mouse), respectively. There were several known features, including a highly acidic 5'-region, a degenerate SH2 domain, and a leucine zipper. These features are consistent with a nuclear protein that regulates transcription, whose extreme conservation underscores the likely importance of this gene in mammalian development. Expression of human and murine SPT6 homologues was analyzed by Northern blotting, which revealed a 7. 0-kb transcript that was expressed constitutively. The SPT6 homologue was mapped to chromosome 17q11.2 in human by somatic cell hybrid analysis and in situ hybridization. These data indicate that SUPT6H and Supt6h are functionally analogous to SPT6 and emb-5 and may therefore regulate transcription through establishment or maintenance of chromatin structure.

Amino Acid Sequence↗

PubMed1996

Immunoreactive S100 proteins of blood immunocytes and brain cells.

Brain S100, an acidic protein with Ca2+-binding and neurotrophic properties, may be involved in the genesis of neurodegenerative diseases. Based on sharing of common antigens between the immune and nervous systems, we performed a comparative analysis of S100 in blood immunocytes (lymphocytes and monocytes) and brain cells. By using polyclonal antibodies to S100, an immunoreactive S100 was detected in human blood immunocytes and U373 human astrocytoma cells. The U373 cells contained a much higher level of S100 as compared to immunocytes, both cell types being compared at 1 X 10(6) cell concentration. Through protein-immunoblotting, the immunocyte antigen was compared with pure S100 of bovine brain (authentic sample) and S100 of U373 cells and brain cells (human and mouse brain). The monomeric form of immunocyte-derived S100 was a low molecular mass (12-14kDa) protein, but slightly larger than authentic S100 (10.5 kDa) The S100 of U373 cells and brain cells was mainly a polymer (60-100 kDa), although the brain cells also showed a low molecular mass (10.5 kDa) band that corresponded to authentic S100. The molecular mass differences suggest that peripheral blood immunocytes contain an immunoreactive S100 that differs in size but is antigenically related to brain S100 family.

Adult↗

PubMed1996

A novel multicolor hybridization scheme applied to localization of a transcribed sequence (D10S170/H4) and deletion mapping in the thyroid cancer cell line TPC-1.

The sequence-tagged site (STS) D10S170, also referred to as H4, is a gene of unknown function. Its 5' end was found fused to the catalytic domain of the RET protooncogene to generate RET/PTC 1, the most common form of PTC oncogenes in human papillary thyroid carcinoma. This gene has previously been assigned to a very large genomic region, 10q11.22-->q22.1. Here, we describe the application of a novel hybridization scheme to the physical and genetic mapping of D10S170. First, we selected a homologous large-insert DNA clone from a human P1 library by filter hybridization and confirmed its authenticity by Southern blot analysis. Triple-color fluorescence in situ hybridization (FISH) experiments mapped this clone to l0q21.2-->q21.3. "Binning" experiments were performed using a quadruple-color FISH approach aimed toward placing the gene in a genetic interval defined by differentially labeled P1 DNA probes containing known polymorphic markers. We found that multicolor FISH greatly expedites chromosomal mapping. Finally, we applied our FISH approach to determine the extent of deletion involving this locus (D10S170) in a papillary thyroid cancer cell line, TPC-1.

Carcinoma, Papillary↗

PubMed1995

Localization of cDNAs to a region poorly represented in the CEPH chromosome 21 YAC contig: candidate genes for genetic diseases mapped to 21q22.3.

Fifty-three cDNA fragments previously obtained by hybridization selection from random clones in the chromosome 21 cosmid library LL21CNO2 failed to identify clones in the chromosome 21 YAC contig described by Chumakov et al. (1992, Nature 359: 380-387). Using an expanded panel of somatic cell hybrids, we have verified that the majority of these cDNAs map to chromosome 21 and that in particular a very high proportion, approximately 85%, localize to a 5-Mb region of distal 21q22.3. Pulsed-field analysis coupled with information from the NotI restriction map of the region further indicate that 17 cDNA fragments map within 650 kb of the PFKL gene and thus may be candidates for genetic diseases linked to this gene. This work helps to characterize a region poorly represented in the CEPH YAC contig and adds to the number of cDNAs useful in analysis of chromosome 21-associated diseases.

Animals↗

PubMed1995

Expressed sequence tags from the long arm of human chromosome 21.

We isolated expressed sequence tags (ESTs) on the long arm of chromosome 21. The ESTs were mapped by PCR using a monochromosomal somatic-cell mapping panel. Of a total of 55 cDNAs, 30 mapped back uniquely to chromosome 21, 7 mapped back to other chromosomes including chromosome 21, 8 mapped back to chromosomes other than 21, and 10 could not be assigned using this methodology. The 30 chromosome 21-specific markers so isolated represent useful EST markers. A rapid PCR-based method was used to delineate the expression pattern of these 30 pairs in different tissues.

Animals↗

PubMed1995

Structure of the human aggrecan gene: exon-intron organization and association with the protein domains.

The complete exon-intron organization of the human aggrecan gene has been defined, and the exon organization has been compared with the individual domains of the protein core. A yeast artificial chromosome containing the aggrecan gene was selected from the Centre d'Etude du Polymorphisme Humaine yeast artificial chromosome library. A cosmid sulibrary was created from this, and direct sequencing of individual cosmids was used to provide the exon-intron organization. The human aggrecan gene was found to be composed of 19 exons ranging in size from 77 to 4224 bp. Exon 1 is non-coding, whereas exons 2-19 code for a protein core of 2454 amino acids with a calculated mass of 254379 Da. Intron 1 of the gene is at least 13 kb. Overall, the sizes of the 18 introns range from 0.5 to greater than 13 kb. Each intron begins with a GT and ends with an AG, thus obeying the GT/AG rule of splice-junction sequences. The entire coding region is contained in 39.4 kb of the gene. The organization of exons is strongly related to the specific domains of the protein core. The A loop of G1 and the interglobular domain are encoded by exons 3 and 7 respectively. The B and B' loops of G1 are encoded by exons 4-6, and those of G2 are encoded by exons 8-10. These sets of exons, coding for the B and B' loops, are identical in size and organization. This is supported by the intron classes associated with these exons. Exon 11 codes for the 5' half of the keratan sulphate-rich region, and exon 12 codes for the 3' half of the keratan sulphate-rich region as well as the entire chondroitin sulphate-rich region. G3 is encoded by exons 13-18, including the alternatively spliced epidermal growth factor-like and complement regulatory protein-like domains. The correspondence between the exon organization and the protein domains argues strongly for modular assembly of the aggrecan gene.

Aggrecans↗

PubMed1995

Construction of a panel of transgenic mice containing a contiguous 2-Mb set of YAC/P1 clones from human chromosome 21q22.2.

Libraries of the entire human genome, or regions of the genome, have been made in bacteria, yeast, and somatic cells. We have expanded this strategy using overlapping YACs and P1s from human 21q22.2 (the Down syndrome region) to create a panel of transgenic mice containing DNA that encompasses this region of the human genome. Together the members of the in vivo library, each with a unique transgene (four YACs and four P1s), contain approximately 2 Mb of contiguous DNA. The integrity, stable inheritance, and expression of a coding sequence for each member of the YAC panel are demonstrated, and the uses of the panel are described.

Animals↗

PubMed1995

Quantitative DNA fiber mapping.

The assembly of sequence ready, high-resolution physical maps and construction of minimally overlapping contigs for the human as well as model genomes requires accurate determination of the extent of overlap between adjacent clones as well as their relative orientation. This is presently done by procedures such as clone fingerprinting, Southern blot analysis or clone end sequencing. We present a complementary analytical technique to map directly cloned DNA sequences on to individual stretched DNA molecules. This approach uses the hydrodynamic force of a receding meniscus to prepare straight high molecular weight DNA molecules that provide a linear template of approximately 2.3 kb/microns on to which the cloned probes can be mapped by in situ hybridization. This technique has numerous advantages such as a very high density of mapping templates, reproducible stretching of the mapping template providing a linear genomic scale, determination of clone orientation and direct visualization of DNA repeats. The utility and accuracy of quantitative DNA fiber mapping are illustrated through three examples: (i) mapping of lambda DNA restriction fragments along linearized approximately 49 kb long lambda phage DNA molecules with approximately 1 kb precision; (ii) localization of the overlap between a cosmid and a colinear P1 clone; and (iii) mapping of P1 clones along an approximately 490 kb yeast artificial chromosome (YAC) with approximately 5 kb precision and estimation of the approximately 25 kb gap between them.

Bacteriophage lambda↗

PubMed1994

Effect of substance P and protein kinase inhibitors on beta-amyloid peptide-induced proliferation of cultured brain cells.

The present study investigated the effect of substance P (SP) and protein kinase inhibitors (H7 and HA1004) on beta-amyloid peptide-induced proliferation of neonatal rat brain cells in primary cultures. The beta-amyloid peptide1-28 (designated as beta AP28), at nanomolar concentrations (10(-9) M), significantly (P < or = 0.05) increased the proliferation of brain cells (presumably non-neuronal) as measured by [3H]thymidine uptake into DNA (mitogenesis). The effect was dependent on time of culture, concentration of beta AP28, and presence of fetal calf serum. The supplementation of SP into cell cultures at time zero reversed the proliferative response of beta AP28. Moreover, the beta AP28-induced proliferation was inhibited by protein kinase inhibitor H7, but not by HA1004. Since H7 is a selective protein kinase C (PKC) inhibitor and SP action involves PKC, we conclude that beta AP28 induces normal brain cell proliferation through PKC pathway of cell signaling.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1994

Isolation and mapping of human chromosome 21 cDNA: progress in constructing a chromosome 21 expression map.

We have isolated 175 cDNA clones from a fetal brain library by direct cDNA selection using genomic DNA isolated from pools of human chromosome 21 (HC21) cosmids. DNA sequences have revealed that 16 of these cDNA clones contain overlapping sequences. Of the other 159 cDNA sequences, 10 match previously identified HC21 genes, and 9 match previously determined cDNA sequences, including the Wilms tumor related transcript (QM), the human testican cDNA, the mammalian calponin cDNA, and 6 anonymous expressed sequence tags. All isolated cDNAs were hybridized to their corresponding cosmids, which suggests that they originated from HC21. We have localized 92 cDNA clones to previously reported HC21q YACs. The remaining unmapped cDNAs contain either sequences not included in the isolated HC21q YACs or sequences that hybridize to yeast DNA. The cDNAs not included in the YACs should be useful in isolating new YACs to bridge the gaps. PCR primers were derived from 4 novel cDNA sequences that had been mapped to the YACs in the suspected Down syndrome region and used in RT-PCR analysis. All 4 primer sequences amplified RNA fragments with the expected sizes, suggesting that these sequences could be used for expression analysis. The construction of a chromosome 21 cDNA map not only is important in the refinement of physical maps, but also will identify a set of genes in the disease regions for detailed characterization.

Base Sequence↗

PubMed1994

Reverse transcription-polymerase chain reaction detection of transcribed sequences on human chromosome 21.

Seventy-four pairs of oligonucleotides derived from sequence-tagged sites (STSs) on the long arm of human chromosome 21, specifically from bands 21q22.1 to 21q22.3, were used in reverse transcription-polymerase chain reactions (RT-PCR) to detect the presence of expressed sequences in a fetal brain. These STSs included 69 that had not been related to transcribed sequences and 5 that had detected two known genes and three previously isolated cDNA clones. Of the 69 STSs analyzed in RT-PCR, 25 allowed amplification of specific cDNA fragments. The sizes of amplified cDNA fragments match those amplified from either human genomic DNA or somatic hybrid cells containing human chromosome 21. Of the 11 cDNA analyzed in Northern blot hybridizations, 6 hybridized to specific RNA species. The rapid screening for cDNA using previously mapped STSs has provided insight into the distribution of expressed sequences in this region of chromosome 21. Northern blot analysis of the amplified cDNA fragments has revealed interesting candidate genes in two disease loci. The marker D21S267 was previously mapped in the Down syndrome region of chromosome 21, and the marker D21S113 is closely linked to progressive myoclonus epilepsy. The cDNA fragments amplified using the primer sequences derived from D21S267 and D21S113 hybridized to 7- and 6.5-kb transcripts, respectively, which seem to express predominantly in brain.

Blotting, Northern↗

PubMed1994

The human apolipoprotein(a)/plasminogen gene cluster contains a novel homologue transcribed in liver.

Lipoprotein(a) is an atherogenic lipoprotein whose function and plasma concentration reflect the structure and regulation of the apolipoprotein(a) gene. Apolipoprotein(a) is a close homologue of plasminogen, and their genes are tightly linked on chromosome 6. To further characterize these genes, we analyzed overlapping human genomic yeast artificial chromosome clones, which revealed a cluster of four highly homologous genes encoding apolipoprotein(a), plasminogen, and two apolipoprotein(a)-related genes (rg) or pseudogenes. Hybridization analysis and reverse transcriptase polymerase chain reaction showed that one of these novel genes, designated apolipoprotein(a)rg-C, has a domain structure similar to apolipoprotein(a) and is transcribed in human liver. Three additional homologues designated as plasminogen-related genes are shown to be unlinked to this gene cluster and reside on chromosomes 2 and 4.

Apolipoproteins A↗

PubMed1993

Combined therapy of mitomycin C and Chinese medical herbs on experimental liver cancer.

In this research, ICR male mice were chosen for intrahepatic implantation of sarcoma 180 tumor cells (1 x 10(7)). The mice were randomly divided into various groups 24 hours after implantation. One of the groups was the tumor control, the others were singly or combinedly treated with mitomycin C (MMC) and Shih Chuan-Ta-Pu-Tang (SCTPT) or Shi-Hung-One (SHO). The results revealed that the mortality rate (MR60) in the tumor control was 100% and the mean survival time (MST60) was 21.11 +/- 10.69 days. The best therapeutic effect appeared in the group treated with the combination of MMC and SHO, its MR6o was 55.0% and MST 60 was 47.0 +/- 13.4 days.

Animals↗

PubMed1993

[Analysis of relative degree of the grey system on socioeconomic factors contributing to malaria transmission].

This paper reports relative degree of the grey system analysis on socioeconomic factors contributing to malaria transmission in Hainan province. The results indicated that the prior factors related to malaria transmission are economic conditions, primary health care, human behavior and culture. It is suggested that rebuilding primary health care and strengthening health propaganda would be advantageous to malaria control in these areas.

China↗

PubMed1991

Sequence and comparative analysis of the rabbit alpha-like globin gene cluster reveals a rapid mode of evolution in a G + C-rich region of mammalian genomes.

A sequence of 10,621 base-pairs from the alpha-like globin gene cluster of rabbit has been determined. It includes the sequence of gene zeta 1 (a pseudogene for the rabbit embryonic zeta-globin), the functional rabbit alpha-globin gene, and the theta 1 pseudogene, along with the sequences of eight C repeats (short interspersed repeats in rabbit) and a J sequence implicated in recombination. The region is quite G + C-rich (62%) and contains two CpG islands. As expected for a very G + C-rich region, it has an abundance of open reading frames, but few of the long open reading frames are associated with the coding regions of genes. Alignments between the sequences of the rabbit and human alpha-like globin gene clusters reveal matches primarily in the immediate vicinity of genes and CpG islands, while the intergenic regions of these gene clusters have many fewer matches than are seen between the beta-like globin gene clusters of these two species. Furthermore, the non-coding sequences in this portion of the rabbit alpha-like globin gene cluster are shorter than in human, indicating a strong tendency either for sequence contraction in the rabbit gene cluster or for expansion in the human gene cluster. Thus, the intergenic regions of the alpha-like globin gene clusters have evolved in a relatively fast mode since the mammalian radiation, but not exclusively by nucleotide substitution. Despite this rapid mode of evolution, some strong matches are found 5' to the start sites of the human and rabbit alpha genes, perhaps indicating conservation of a regulatory element. The rabbit J sequence is over 1000 base-pairs long; it contains a C repeat at its 5' end and an internal region of homology to the 3'-untranslated region of the alpha-globin gene. Part of the rabbit J sequence matches with sequences within the X homology block in human. Both of these regions have been implicated as hot-spots for recombination, hence the matching sequences are good candidates for such a function. All the interspersed repeats within both gene clusters are retroposon SINEs that appear to have inserted independently in the rabbit and human lineages.

Animals↗