Search PubMed⌕ Search

Biomedical subjects

C L Hsieh

Publications and source records attributed to C L Hsieh.

At least 73 records · Page 4Linked to original sources
PubMed1996

Human gamma-aminobutyraldehyde dehydrogenase (ALDH9): cDNA sequence, genomic organization, polymorphism, chromosomal localization, and tissue expression.

The cDNA and the gene (ALDH9) for a human aldehyde dehydrogenase isozyme, which has a high activity for oxidation of gamma-aminobutyraldehyde and other amino aldehydes, were cloned and characterized. The cDNA has an open reading frame of 1479 bp encoding 493 amino acid residues. The gene is about 45 kb and consists of 10 coding exons interrupted by nine introns. The gene was assigned to chromosome 1q22-q23, using fluorescence in situ hybridization. Northern blot hybridization indicated that the size of the mRNA is about 2.4 kb and that the gene is expressed at high levels in adult liver, skeletal muscle, and kidney and low levels in heart, pancreas, lung, and brain. The gene is polymorphic, i.e., C or T at nt 327 and C or G at nt 344.

Adult↗
PubMed1996

Processing of branched DNA intermediates by a complex of human FEN-1 and PCNA.

In eukaryotic cells, a 5' flap DNA endonuclease activity and a ds DNA 5'-exonuclease activity exist within a single enzyme called FEN-1 [flap endo-nuclease and 5(five)'-exo-nuclease]. This 42 kDa endo-/exonuclease, FEN-1, is highly homologous to human XP-G, Saccharomyces cerevisiae RAD2 and S.cerevisiae RTH1. These structure-specific nucleases recognize and cleave a branched DNA structure called a DNA flap, and its derivative called a pseudo Y-structure. FEN-1 is essential for lagging strand DNA synthesis in Okazaki fragment joining. FEN-1 also appears to be important in mismatch repair. Here we find that human PCNA, the processivity factor for eukaryotic polymerases, physically associates with human FEN-1 and stimulates its endonucleolytic activity at branched DNA structures and its exonucleolytic activity at nick and gap structures. Structural requirements for FEN-1 and PCNA loading provide an interesting picture of this stimulation. PCNA loads on to substrates at double-stranded DNA ends. In contrast, FEN-1 requires a free single-stranded 5' terminus and appears to load by tracking along the single-stranded DNA branch. These physical constraints define the range of DNA replication, recombination and repair processes in which this family of structure-specific nucleases participate. A model explaining the exonucleolytic activity of FEN-1 in terms of its endonucleolytic activity is proposed based on these observations.

Antibodies, Monoclonal↗
PubMed1996

A comparison of performance in added-purpose occupations and rote exercise for dynamic standing balance in persons with hemiplegia.

OBJECTIVES: Adding purpose to daily occupations to promote performance is a basic premise of occupational therapy. This study investigated the hypothesis that in persons with hemiplegia, two added-purpose occupations would elicit more exercise repetitions than a rote exercise. METHOD: In a counterbalanced order, 21 subjects with hemiplegia, aged 51 to 78 years, experienced all three conditions of a dynamic standing balance exercise that involved bending down, reaching, standing up, and extending the arm. One condition of added purpose involved the use of materials (small balls and target); a second added-purpose condition involved the subjects' imagination of the small balls. The third condition was the rote exercise without added purpose. RESULTS: A one-way analysis of variance for related measures indicated that the subjects performed significantly differently in each of the three conditions (p < .001). A Tukey multiple comparison test revealed that the subjects did significantly more exercise repetitions in the added-materials condition and in the imagery-based condition than in the rote exercise condition (p < .05). CONCLUSION: This study demonstrates how added purpose can enhance motor performance in persons with hemiplegia. Purpose may be effectively added to an exercise through the use of materials or imagery.

Aged↗
PubMed1995

Improved gene expression by a modified bicistronic retroviral vector.

We have previously described the construction of a bicistronic retroviral vector using the picornavirus internal ribosome entry site (IRES), which allows two genes expression simultaneously from a single transcript. This vector transcribes RNA efficiently; however, in some cases the levels of protein production are low. In this report, we further modified the bicistronic vector by abolishing the functional viral gag initiation codon that is retained in the vector at 5' to the first initiation codon of transduced gene. Five different genes, human interleukin 2 (hIL-2), human interleukin 4 (hIL-4), human granulocyte macrophage stimulating factor (hGM-CSF), herpes simplex virus thymidine kinase (HSV-tk) gene, and hepatitis C virus (HCV) core gene (C190), were tested on this modified vector for gene transfer and expression. Our results demonstrated that the new bicistronic vector greatly increased the protein levels when compared with the original one. As the RNA levels and splicing patterns from these two vectors remained similar, the improvement was most likely resulted from the increased translational efficiency.

Animals↗
PubMed1995

Satellited 4q identified in amniotic fluid cells.

Extra material was identified on the distal long arm of a chromosome 4 in an amniotic fluid specimen sampled at 16.6 weeks of gestational age. There was no visible loss of material from chromosome 4, and no evidence for a balanced rearrangement. The primary counseling issue in this case was advanced maternal age. Ultrasound findings were normal, and family history was unremarkable. The identical 4qs chromosome was observed in cells from a paternal peripheral blood specimen and appeared to be an unbalanced rearrangement. This extra material was NOR positive in lymphocytes from the father, but was negative in the fetal amniocytes. Father's relatives were studied to verify the familial origin of this anomaly. In situ hybridization with both exon and intron sequences of ribosomal DNA demonstrated that ribosomal DNA is present at the terminus of the 4qs chromosome in the fetus, father, and paternal grandmother. This satellited 4q might have been derived from a translocation event that resulted in very little or no loss from the 4q and no specific phenotype. This derivative chromosome 4 has been inherited through at least 3 generations of phenotypically normal individuals.

Amniotic Fluid↗
PubMed1995

Determination of lysine with ninhydrin-ferric reagent.

Ninhydrin-ferric reagent reacts highly and specifically with lysine at a pH value of 1.0. Ferric ion inhibits the reaction of ninhydrin with proline, ornithine, glycine, arginine, and histidine. This method can be used to determine a lysine sample of high concentration without dilution. It has a linear response range from 0.0625 to 0.5 mg lysine.HCl.

Ferric Compounds↗
PubMed1995

Sequence of human FEN-1, a structure-specific endonuclease, and chromosomal localization of the gene (FEN1) in mouse and human.

We recently purified and cloned the gene for a DNA structure-specific endonuclease, FEN-1, from murine cells. The murine protein recognizes 5' DNA flap structures that have been proposed in DNA replication, repair, and recombination. Here, we report the sequence of the human FEN1 gene. The translated sequence is identical to peptide sequence obtained from maturation factor-1, which is 1 of the 10 essential proteins for cell-free DNA replication. The human protein has the same structure-specific DNA endonuclease activity as the murine protein. Two human chromosomal hybridization signals, 11q12 and 1p22.2, were observed by FISH analysis using human genomic clones homologous to the mouse Fen-1 gene. The localization on human 11q12 was confirmed using radiation-reduced hybrids. The mouse Fen-1 gene is assigned to chromosome 19 based on somatic cell hybrids. The significance of these FEN1 gene localizations in human and mouse is discussed.

Amino Acid Sequence↗
PubMed1995

The interaction of the somatosensory evoked potentials to simultaneous finger stimuli in the human central nervous system. A study using direct recordings.

In order to investigate the interaction of sensory electrophysiologic fields arising from the adjacent second (II) and third (III) fingers and the distant second and fifth (V) fingers, direct recordings of somatosensory evoked potentials (SEPs) were performed from the sensory and motor cortices, the sensory thalamic nucleus (nucleus ventralis caudalis, VC) and the cuneate nucleus in humans during neurosurgical operations. Electrical stimulation was given to the II, III or V fingers individually, and also to pairs of either the II and III fingers or the II and V fingers simultaneously. The interaction ratio (IR) was devised as the ratio of amplitude attenuation caused by the simultaneous stimulation to two fingers compared with the amplitude of the arithmetically summed SEPs to the individual stimulation of two fingers. The IRs were calculated on N20 and P25 from the sensory cortex, P22 from the motor cortex, P17thal from the VC, and N16cune and P35cune from the cuneate nucleus. With both stimulations to the II and III fingers and the II and V fingers, P25 showed the greatest IR, followed by P22, then by P17thal, with N16cune exhibited the smallest IR. N20 and P35cune showed similar IRs and significantly greater IRs with II and III finger stimulation compared with II and V finger stimulation. These results thus indicate that the interaction of somatosensory impulses occurs in several structures along the sensory pathway in CNS, including the cuneate nucleus, the sensory thalamic nucleus, as well as sensory and motor cortices, with the greatest IRs in the cerebral cortices and the weakest ones in the brain-stem.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Molecular cloning, genomic organization, and chromosomal localization of an additional human aldehyde dehydrogenase gene, ALDH6.

Aldehyde dehydrogenase isozymes have been suggested to play a major role in the detoxification of aldehydes generated by alcohol metabolism and lipid peroxidation. We previously cloned and characterized four human nonallelic ALDH genes encoding different isozymes. The existence of an unique ALDH isozyme in human saliva and its polymorphism has been demonstrated previously. In this paper, we describe the cloning, characterization, and chromosomal mapping of an aldehyde dehydrogenase gene (ALDH6) expressed in the human salivary gland. The cloned ALDH6 cDNA is 3457 bp in length and contains an open reading frame encoding 512 amino acid residues. The deduced amino acid sequence showed that ALDH6 is larger than the human liver ALDH1 by 11 amino acid residues at the N-terminal, and the degree of identity between the two isozymes is 70% with an alignment of 500 amino acid residues. The human ALDH6 gene spans about 37 kb and consists of 13 exons. The putative TATA and CCAAT boxes and Sp1 binding sites are found in the 5' upstream region of the gene. Northern blot analysis demonstrated that the ALDH6 gene is expressed at low levels in many tissues and at higher levels in salivary gland, stomach, and kidney. The ALDH6 gene was assigned to chromosome 15q26 using fluorescence in situ hybridization.

Aldehyde Dehydrogenase↗
PubMed1994

Terminal deletion of the long arm of chromosome 2 in a premature infant with karyotype: 46,XY,del(2)(q37).

We present a premature newborn boy with multiple congenital anomalies, including craniofacial anomalies, syndactyly, cardiac defects, and a horseshoe kidney associated with terminal deletion of 2q. The infant's karyotype was 46,XY,del(2)(q37). Clinical, cytogenetic, and autopsy findings are presented in this report. Clinical manifestations in this infant are compared with those four other known patients with terminal deletion of chromosome 2.

Abnormalities, Multiple↗
PubMed1994

Structure and localization on the X chromosome of the gene coding for the human filopodial protein moesin (MSN).

Moesin is a member of a recently discovered family of closely related proteins that includes ezrin, radixin, and merlin. It is widely expressed in different tissues and cells and has been localized to filopodia and other membranous protrusions that are important for cell-cell recognition and signaling and cell movement. Here, we have localized the coding gene (MSN) to Xq11.2-q12 by Southern and Western blot analyses of Chinese hamster x human somatic cell hybrids and by fluorescence chromosomal in situ hybridization. Moesin-like sequences were identified on chromosomes 5 and 6. The murine Msn locus was mapped to the X chromosome as well by studying a rodent x mouse hybrid panel. The structure of the human moesin gene has been determined. The 12 exons are distributed over > 30 kb, and the exon/intron junctions demarcate individual highly conserved domains. Primer extension analysis revealed two major start transcription sites, 184 and 133 bp upstream of the initiation codon. The 5'-flanking region is GC-rich, lacks a TATA box, and contains four SP1 and one AP1 binding sites.

Animals↗
PubMed1994

Dependence of transcriptional repression on CpG methylation density.

CpG methylation is known to suppress transcription. This repression is generally thought to be related to alterations of chromatin structure that are specified by the methylation. The nature of these chromatin alterations is unknown. Moreover, it has not been clear if the methylation repression occurs in an all-or-none fashion at some critical methylation density, or if intermediate densities of methylation can give intermediate levels of repression. Here I report a stable episomal system which recapitulates many dynamic features of methylation observed in the genome. I have determined the extent of transcriptional repression as a function of four densities of CpG methylation. I find that the repression is a graded but exponential function of the CpG methylation density such that low levels of methylation yield a 67 to 90% inhibition of gene expression. Higher levels of methylation extinguished gene expression completely. Transcription from methylated minichromosomes can be increased by butyrate treatment, suggesting that histone acetylation can reverse some of the repression specified by the methylated state. Sites of preferential demethylation occurred and may have resulted from transcription factor binding or DNA looping.

5-Methylcytosine↗
PubMed1993

V(D)J recombination in ataxia telangiectasia, Bloom's syndrome, and a DNA ligase I-associated immunodeficiency disorder.

Ataxia telangiectasia (AT) and Bloom's syndrome (BS) patients are characterized by sensitivity to radiation, increased lymphoid malignancy, and frequent translocations to the antigen receptor loci. Because of these features, there has been a persistent question as to whether the V(D)J recombinase might be abnormal in cells from these patients. Such abnormalities might be due to inappropriate to inaccurate expression of components of the V(D)J recombinase or due to mutation in a component shared between V(D)J recombination and other cellular processes, such as DNA repair. Bloom's syndrome is associated with a ligation deficiency, and this activity may contribute in the end resolution steps of both site-specific and general DNA-processing reactions. In the current study, we have activated V(D)J recombination in normal, AT, and BS fibroblasts and in fibroblasts from a patient with mutations that largely abolish DNA ligase I activity. We find that the signal and coding joint formation of the V(D)J recombination reaction are entirely normal in AT, BS, and DNA ligase I mutant cells. In addition to ruling out abnormalities of the V(D)J recombinase in AT, BS, and DNA ligase I mutant cells, these studies suggest that DNA ligase I is unlikely to be required for signal or coding end joining in the V(D)J recombination reaction.

Ataxia Telangiectasia↗
PubMed1993

Somatic hypermutation of an immunoglobulin mu heavy chain transgene.

We have analyzed somatic hypermutation of an immunoglobulin (Ig) heavy chain transgene. Hybridomas expressing the transgene were produced from immunized transgenic mice and transgene copies were sequenced to assay for mutation. In two IgM-producing hybridomas, as well as in several IgG-producing hybridomas, mutations were found in the VDJ region of the transgene. In the IgM-producing hybridomas, both mutated and unmutated transgene copies were present and expressed as mRNA. Several mutated transgene copies were present in a single cell and these showed different patterns of mutation. Two IgG-producing hybridomas isolated from a single animal also showed a hierarchical pattern of mutation indicating that transgene mutations can accumulate during B cell proliferation, similar to the mutational process for endogenous antibody genes. Among hybridomas that expressed both IgG and IgM molecules derived from the transgene, the isotype-switched gamma transgene copy exhibited a higher level of mutation than the mu transgene copies. Our results indicate that the 15-kb ARSmu transgene contains all the sequence information required to target the Ig-specific hypermutational machinery, and raise the possibility that sequences associated with the endogenous CH locus might enhance somatic mutation.

Amino Acid Sequence↗
PubMed1993

The human homolog of the glomerulosclerosis gene Mpv17: structure and genomic organization.

Mice carrying a retroviral insert in both alleles of the Mpv17 gene develop glomerulosclerosis and nephrotic syndrome at young age. Thus, the Mpv17 gene is a recessive disease gene in mice and this mouse strain is a potential animal model for glomerular diseases in man. We here describe the isolation and analysis of a human homolog of this gene. By interspecies hybridisation cDNA clones representing a single RNA species were isolated from human liver. Sequence analysis revealed over 90% identify in a region coding for a protein of 176 amino acids and unknown function in both species. Cloning of the genomic locus revealed a single copy gene which we mapped to the short arm of chromosome 2 at band 2p23-p21. Determination of the intron-exon structure and the junction sequences enabled us to establish a PCR based procedure to isolate the coding region from human genomic DNA. Thus, it is now possible to analyse patients suffering from candidate diseases on the basis of a blood sample if biopsy material is not available.

Animals↗
PubMed1992

Tissue-specific expression and chromosome assignment of genes specifying two isoforms of subunit VIIa of human cytochrome c oxidase.

Subunit VIIa of mammalian cytochrome c oxidase (COX; EC 1.9.3.1) exists in at least two isoforms, one present in all tissue types ('liver' isoform; COX VIIa-L) and the other specific for cardiac and skeletal muscle (COX VIIa-M). We have isolated a full-length cDNA encoding human COX VIIa-M. The deduced polypeptide represents the human ortholog of COX VIIa-M, as it shares 78% identity with bovine COX VIIa-M, but only 63% identity with human COX VIIa-L. Northern-blot analysis of primate tissues demonstrated that COXVIIa-M mRNA is present only in muscle tissues; in contrast, the COXVIIa-L mRNA is present in both muscle and nonmuscle tissues. Southern-blot hybridization of human-rodent cell hybrid genomic DNA indicates that the COXVIIa-M gene maps to a single locus on chromosome 19, designated COX7AM. In contrast, COXVIIa-L cDNA probes hybridized to fragments from two COX7AL loci, on chromosomes 4 and 14.

Amino Acid Sequence↗
PubMed1992

V(D)J recombination on minichromosomes is not affected by transcription.

It has been shown previously by others that transcription is temporally correlated with the onset of V(D)J recombination at the endogenous antigen receptor loci. We have been interested in determining whether this temporal correlation indicates a causal connection between these two processes. We have compared V(D)J recombination minichromosome substrates that have transcripts running through the recombination zone with substrates that do not in a transient transfection assay. In this system, the substrates acquire a minichromosome conformation within the first several hours after transfection. We find that the substrates recombine equally well over a 100-fold range in transcriptional variation. In additional studies, we have taken substrates that have low levels of transcription and inhibited transcription further by methylating the substrate DNA or by treating the cells with a general transcription inhibitor (alpha-amanitin). Although these treatments decrease the level of expression an additional 10-100-fold, there is still no observable effect on V(D)J recombination. Based on these results, we conclude that transcription is not necessary for the V(D)J reaction mechanism and does not alter substrate structure at the DNA level or at the simplest levels of chromatin structure in a way that affects the reaction.

Abelson murine leukemia virus↗