Biomedical subjects

M H Lin

Publications and source records attributed to M H Lin.

At least 19 recordsLinked to original sources

PubMed2001

Induction of disabled-2 gene during megakaryocyte differentiation of k562 cells.

Megakaryocyte differentiation is often accompanied by the changes of gene expression pattern. Here we reported that the expression of DAB2, a putative adaptor protein in cell signaling, was induced at the protein and mRNA levels upon 12-O-tetradecanoylphorbol-13-acetate-mediated megakaryocyte differentiation of human chronic myeloid leukemic K562 cells. On the other hand, the differentiation agents DMSO and retinoic acid had no effect on DAB2 expression. Analysis of promoter activity with the human DAB2 luciferase reporter constructs suggested that the regulation is partially at the transcriptional level. The responsive sequences located within an 80-bp DAB2 promoter region. To determine the involvement of MEK1-p42/p44 MAPK pathway in mediating DAB2 gene expression, we have performed the following experiments and found that (i) there was sustained activation of p42/p44 MAPK, but not p38 MAPK, upon K562 cells differentiation; (ii) application of MEK1 inhibitor U0126 reduced the expression of DAB2 protein, mRNA and promoter activity, as well as cell differentiation; (iii) constitutively active MEK1 increased DAB2 promoter activity; and (iv) dominant negative ERK2 abolished constitutively active MEK1-induced DAB2 promoter activity. Taken together, our results indicate that DAB2 gene is induced upon megakaryocyte differentiation by the MEK1-p42/p44 MAPK pathway and may define a new role of DAB2 in hematopoietic cell differentiation.

Adaptor Proteins, Signal Transducing↗

PubMed2001

The dilemma of "to-be or not-to-be": needs and expectations of the Taiwanese cadaveric organ donor families during the pre-donation transition.

There has been little study of the Chinese cadaveric donor family's decisions to donate organs within the Chinese cultural framework. A convenience sample of 25 cadaveric donor family members (12 men, 13 women) who gave their consent to donation at National Taiwan University Hospital agreed to participate in this study and completed in-depth interviews. Data were analyzed by a three-steps within-method qualitative triangulation method. The factors influencing the donor family's decisions to donate organs, the needs of donor families, and their expectations of health care providers during the pre-donation transition--the critical period of time between signing a donation and consent to organ harvesting--were examined. The background context and a conceptual framework were further developed to discuss and depict this phenomenon. This project aims to broaden the horizon on organ donation and contribute to the understanding of some of the psychodynamic issues in the Chinese family in Taiwan.

Adult↗

PubMed2001

Real-time quantitative PCR analysis for alpha-thalassemia-1 of Southeast Asian type deletion in Taiwan.

Since homozygosity of the alpha-thalassemia-1 of Southeast Asian (SEA) type deletion results in hydrops fetalis, a novel protocol based on the real-time quantitating polymerase chain reaction (PCR) technique has been developed to quantify the intact and aberrant alpha-globin genes in adults. The ratio of the normal/SEA-bearing alpha-globin genes was expressed in cycle threshold (C(T)) values. Theoretically, a relative ratio of one to one was anticipated in individuals carrying the SEA type deletion. Twenty-five heterozygous and 20 normal cases were analyzed retrospectively with this protocol. Data showed that the CT values for the intact alpha-globin gene allele and the allele bearing the SEA type deletion in carriers were 28.74+/-1.49 and 26.46+/-2.05, respectively. Therefore, the ratio of normal/SEA type deletion-bearing alpha-globin genes in the carriers was 1.09+/-0.043. No ambiguous results were observed from other less common genotypes associated with alpha-thalassemia, such as the Philippine type deletion. Based on the results, we concluded that this protocol could provide a rapid method to mass screen carriers with alpha-thalassemia-1 of SEA type deletion in this region.

Alleles↗

PubMed2001

Specificity of the histopathological triad for the diagnosis of toxoplasmic lymphadenitis: polymerase chain reaction study.

Toxoplasmosis is a common cause of lymphadenopathy, but toxoplasmic cysts are not usually found in histological sections used for establishing diagnosis, except on extremely rare occasions. The histopathological triad of florid reactive follicular hyperplasia, clusters of epithelioid histiocytes, and focal sinusoidal distention by monocytoid B cells has been considered to be diagnostic of toxoplasmic lymphadenitis, but the validity of the histopathological triad is based indirectly on serological correlation only. The demonstration of Toxoplasma gondii DNA in lymph nodes displaying the histopathological triad will indicate the validity of the histopathological triad as the criterion for the histopathological diagnosis of toxoplasmic lymphadenitis. We used frozen tissues of 12 lymph nodes with the histopathological triad and tissues of 27 lymph nodes from patients with various other conditions (including 13 cases of follicular lymphoid hyperplasia, FLH; three cases of dermatopathic lymphadenopathy, DPL; two cases of plasmacytosis; two cases of Castleman's disease; two cases of metastatic adenocarcinoma; and five cases of lymphoma) to detect T. gondii DNA by polymerase chain reaction. Ten out of 12 lymph nodes with the triad and six out of 27 lymph nodes without the triad were positive for T. gondii DNA. Thus, the sensitivity of the triad was 62.5% (10/16) and the specificity was 91.3% (21/23). The predictive value of positive tests was 83.3% (10/12) and the predictive value of negative tests was 77.7% (21/27). The six cases positive for T. gondii DNA without the triad were four cases of FLH, one case of DPL, and one case of plasmacytosis. None of the neoplastic diseases was positive. The false positive and negative cases could be due to sampling problems or past T. gondii infection. The results confirm that the histopathological triad is highly specific for the diagnosis of toxoplasmic lymphadenitis and can be used confidently.

Adolescent↗

PubMed2001

Central venous catheter-induced atrial ectopic tachycardia with reverse alternating Wenckebach periods.

A centrally inserted venous catheter may cause atrial ectopic tachycardia. The association of atrial ectopic tachycardia with spontaneous reverse alternating Wenckebach periodicity has rarely been reported. We describe a 4-year-old boy with tetralogy of Fallot who developed atrial ectopic tachycardia with reverse alternating Wenckebach periods postoperatively after central venous catheter placement. All such episodes emerged from a 3:2 atrioventricular block, followed by runs of 2:1 atrioventricular block with progressive shortening of the conducted PR intervals. Normal sinus rhythm returned after the catheter was withdrawn to the superior vena cava. Reverse alternating Wenckebach periodicity may be a tachycardia-dependent physiologic phenomenon.

Catheterization, Central Venous↗

PubMed2001

A common precursor for the three subunits of L-glutamate oxidase encoded by gox gene from Streptomyces platensis NTU3304.

A segment of DNA containing the L-glutamate oxidase (gox) gene from Streptomyces platensis NTU3304 was cloned. The entire nucleotide sequence of the protein-coding portion consisting of 2130 bp (710 codons, including AUG and UGA) of the cloned DNA fragment was determined. The gox gene contained only one open reading frame (ORF) which coded for a 78-kDa polypeptide, the precursor of active extracellular Gox. Mature Gox is composed of three subunits, designated as alpha, beta, and gamma, with molecular masses of 39, 19, and 16 kDa, respectively. Analyses of the N-terminal amino acid sequences of the subunits revealed that the order of subunits in the precursor polypeptide encoded by the ORF, from N-terminus to C-terminus, is alpha-gamma-beta. The presence of the flavin adenine dinucleotide (FAD)-binding motif place Gox as a member of the flavoenzyme family. Furthermore, a negative effect of glucose on the biosynthesis of Gox was observed when it was used as carbon source.

Amino Acid Oxidoreductases↗

PubMed2001

Spontaneous closure of ventricular septal defects in the first year of life.

BACKGROUND AND PURPOSE: The recent increase in the prevalence of ventricular septal defect (VSD) has been ascribed to the improved detection of small defects with echocardiography and the wider use of screening. The aim of this study was to determine the prevalence and timing of spontaneous closure of specific types of VSD in neonates using echocardiographic screening and follow-up. METHODS: Two-dimensional color Doppler echocardiography was performed in 3,472 clinically normal full-term neonates born at Cathay General Hospital to detect isolated VSD. The relative prevalence of muscular versus perimembranous defects and their outcome in the first year of life were evaluated. RESULTS: VSD was found in 74 neonates (34 male, 40 female), resulting in a prevalence of 21.3/1,000 live births. There were 48 muscular, 25 perimembranous, and one subpulmonic defects. Of the 74 patients, 11 were lost to follow-up. Within the observation period of 12 months, spontaneous closure occurred in 40 patients in the muscular group and in six patients in the perimembranous group. The overall rate of spontaneous closure was 73% by the end of the first year. Only five patients with perimembranous defects received digoxin therapy. CONCLUSIONS: The prevalence of VSD in this series of neonates was 21.3/1,000 live births. The most common location of VSD in the neonatal period was in the region of the muscular septum. Muscular defects were more likely to close spontaneously than perimembranous defects. Most muscular defects underwent spontaneous closure during the 12-month follow-up period.

Age Factors↗

PubMed2000

The Drosophila PAR domain protein 1 (Pdp1) gene encodes multiple differentially expressed mRNAs and proteins through the use of multiple enhancers and promoters.

Transcription factors are often expressed at several times and in multiple tissues during development and regulate diverse sets of downstream target genes by varying their combinatorial interactions with other transcription factors. The Drosophila Tropomyosin I (TmI) gene is regulated by a complex of proteins within the enhancer that synergistically interacts with MEF2 to activate TmI transcription as muscle cells fuse and differentiate. One of the components of this complex is PDP1 (PAR domain protein 1), a basic leucine zipper transcription factor that is highly homologous to three vertebrate genes that are members of the PAR domain subfamily. We have isolated and describe here the structure of the Pdp1 gene. The Pdp1 gene is complex, containing at least four transcriptional start sites and producing at least six different mRNAs and PDP1 isoforms. Five of the PDP1 isoforms differ by the substitution or insertion of amino acids at or near the N-terminal of the protein. At least three of these alternately spliced transcripts are differentially expressed in different tissues of the developing embryo in which PDP1 expression is correlated with the differentiation of different cell types. A sixth isoform is produced by splicing out part of the PAR and basic DNA binding domains, and DNA binding and transient transfection experiments suggest that it functions as a dominant negative inhibitor of transcription. Furthermore, two enhancers have been identified within the gene that express in the somatic mesodermal precursors to body wall muscles and fat body and together direct expression in other tissues that closely mimics that of the endogenous gene. These results show that Pdp1 is widely expressed, including in muscle, fat, and gut precursors, and is likely involved in the transcriptional control of different developmental pathways through the use of differentially expressed PDP1 isoforms. Furthermore, the similarities between Pdp1 and the other PAR domain genes suggest that Pdp1 is the homologue of the vertebrate genes.

Alternative Splicing↗

PubMed2000