PubMed Health⌕ Search

Biomedical subjects

K S Dai

Publications and source records attributed to K S Dai.

13 recordsLinked to original sources
PubMed2001

A novel human striated muscle RING zinc finger protein, SMRZ, interacts with SMT3b via its RING domain.

The RING domain is a conserved zinc finger motif, which serves as a protein-protein interaction interface. Searches of a human heart expressed sequence tag data base for genes encoding the RING domain identified a novel cDNA, named striated muscle RING zinc finger protein (SMRZ). The SMRZ cDNA is 1.9 kilobase pairs in length and encodes a polypeptide of 288 amino acid residues; analysis of the peptide sequence demonstrated an N-terminal RING domain. Fluorescence in situ hybridization localized SMRZ to chromosome 1p33-34. Northern blots demonstrated that SMRZ is expressed exclusively in striated muscle. In the cardiovascular system, SMRZ is more highly expressed in the fetal heart than in the adult heart (slightly higher expression in the ventricle than in the atrium), suggesting that SMRZ is developmentally regulated. SMRZ was found to interact with SMT3b, a ubiquitin-like protein, through the SMRZ-RING domain. This interaction was abolished by mutagenesis of conserved RING domain residues. Transient transfection of SMRZ into C2C12 myoblasts showed localization of SMRZ to the nucleus. These data suggest that SMRZ may play an important role in striated muscle cell embryonic development and perhaps in cell cycle regulation.

Amino Acid Sequence↗
PubMed2000

Molecular cloning and characterization of a novel human gene containing ankyrin repeat and double BTB/POZ domain.

A novel human gene containing an ankyrin repeat and BTB/POZ domains (BPOZ) was isolated from a human leukocyte cDNA library. The cDNA sequence contains an open reading frame of 1434 bp that encodes 478 amino acid residues with a predicted molecular mass of 53.9 kDa. Sequence pattern analysis shows that BPOZ contains an N-terminal ankyrin repeat, a bipartite nuclear localization signal and two BTB/POZ domains. Using semiquantitative RT-PCR, the BPOZ transcript was found to be ubiquitously expressed in all fetal tissues examined (heart, brain, liver, and kidney) suggesting that BPOZ is involved in basic cellular function. Low expression of BPOZ in adult tissues (normal and hypertrophic heart) suggests that BPOZ mRNA is developmentally regulated and may play a role in developmental processes. Chromosomal localization by radiation hybrid mapping revealed that this gene is localized between D3S1269 and D3S3606 markers corresponding to the region of chromosome 3q21, a region frequently associated with leukemia. It is thus suggested that BPOZ may be functionally involved in protein-protein interaction, perhaps in forming protein complexes, and may have an important role in normal development and in the development of leukemia.

Amino Acid Sequence↗
PubMed2000

Apoptosis-related genes expressed in cardiovascular development and disease: an EST approach.

Apoptosis (programmed cell death) is an important process which, in conjunction with cell proliferation, maintains cell number homeostasis. Although apoptosis has been more extensively investigated in other tissues [1,2], only recently has this process been suspected as a significant contributor to both disease and normal development of the cardiovascular system [3-6]. Grasping a comprehension of the underlying genetic mechanisms of apoptosis is especially crucial considering that cardiac myocytes irreversibly exit the cell cycle and thus fail to proliferate during pathological conditions. Despite great strides in understanding the molecular pathways of apoptosis, there still remain numerous questions to be answered. Identifying key genes that are involved in the regulatory process of apoptosis in the cardiovascular system will serve as a basis for creating more effective therapeutic treatments in cardiovascular disease and provide an understanding of how cardiac development is modulated. This review provides a brief summary of recent data implicating genes that may be involved in apoptosis in the cardiovascular system. It also outlines the continued usefulness of large-scale generation of expressed sequence tags (ESTs) to establish expression profiles from the cardiovascular system and as a means of identifying potentially significant apoptotic regulators previously characterized in other tissues but not as yet in the cardiovascular system.

Animals↗
PubMed1999

Chromosomal, in silico and in vitro expression analysis of cardiovascular-based genes encoding zinc finger proteins.

Three hundred and sixty expressed sequence tags (ESTs) from human heart cDNA libraries corresponding to one hundred and twenty six unique zinc finger proteins (ZFPs) were annotated and classified into seven types of ZFPs as reported previously. Among these 126 cvbZFPs (cardiovascular-based ZFPs), the C(2)H(2)-type and the C(2)C(2)-type are the two major ZFP types which account for more than 80% of ZFP genes present in the cardiovascular system. The expression patterns of 11 randomly selected ZFP genes (at least one for each type) in normal fetal, adult and hypertrophic adult hearts, respectively, were determined using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. The results suggest that ZFPs may be involved in the processes of either developmental control (downregulated or upregulated expression) or basic cellular functional regulation (constant expression). Interestingly, PAF-1 (peroxisome assembly factor-1), a C(3)HC(4)-type ZFP (RING domain-containing ZFP) showing a downregulated expression pattern in normal tissues was found to be upregulated in hypertrophic adult heart, suggesting a possible role for this fetal gene in the pathogenesis of cardiac hypertrophy. In silico Northern analysis of 15 tissues showed that over 90% of cvbZFPs demonstrate widespread tissue distribution, suggesting the vast majority of ZFPs are functionally shared among tissues. The potential importance of transcriptional repressors in cardiovascular development and disease, such as HFHZ, was supported by the observation that one-third (39 of 126) of cvbZFPs possess this function. Of these, 26 are C(2)H(2)-type and the remaining 13 included 8 C(2)C(2)-type, 1 C(3)HC(4)-type, 1 C(2)HC(4)C(HD)-type, 2 C(3)H-type and 1 combination type. Of particular interest was the observation that ZFPs which contain a KRAB domain are the major subtype present (51. 3% of the total repressors in cvbZFPs). Chromosomal distribution analysis showed that mapping loci of cvbZFP genes are concentrated on chromosomes 1, 3, 6, 8, 10, 11, 12, 19 and X. In particular, chromosome 19 appears to be enriched in ZFP genes with C(2)H(2)-type as the predominant type present. Overall, this report provides a fundamental initial step toward understanding the potential role of ZFPs in regulating cadiac development and disease.

Adult↗
PubMed1998

Characterization of a novel gene encoding zinc finger domains identified from expressed sequence tags (ESTs) of a human heart cDNA database.

Seven types of zinc finger protein (ZFP) genes based on the combinations of cysteine and histidine residues were found in a human heart cDNA database. Here we report the isolation of 360 cDNA clones encoding putative ZFPs. Of these, 154 (42.8%) represent C2H2-type ZFPs, 101 (28.1%) represent C2C2-type, five (1.4%) represent C2HC-type, 71 (19.7%) represent C2HC4C(HD)-type, three (0.8%) represent C3H-type, eight (2.2%) represent C3HC4-type and 18 (0.5%) represent combination type (genes containing more than one type of zinc finger). Among these 360 ZFPs, a novel ZFP cDNA named HFHZ (human fetal heart ZFP) with sequence homology to a Kruppel-associated box (KRAB) was identified. Sequencing the full-length of this cDNA clone identified an open reading frame of 711 bp that encodes a 237 amino acid protein with a predicted molecular weight of 27.7 kDa. Sequence analysis indicated that HFHZ contained a truncated KRAB box at the N-terminus and two C2H2 zinc fingers at the C-terminus. The transcript of HFHZ is highly expressed in fetal heart and moderately expressed in fetal brain but not expressed in fetal liver as revealed by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis suggesting that HFHZ is not expressed ubiquitously. The 3.3-fold higher expression in the fetal heart than in the adult heart suggests that HFHZ mRNA is downregulated in the process of development. In addition, the relatively high expression (1.9-fold) of HFHZ observed in the hypertrophic as compared to the normal adult heart suggests that this fetal gene is reactivated in response to hypertrophic stimuli. Chromosomal localization by in situ hybridization revealed that this gene is in 19q13.1, a region containing genes involved in both cell cycle and developmental regulation.

Adult↗
PubMed1997

A genome-based resource for molecular cardiovascular medicine: toward a compendium of cardiovascular genes.

BACKGROUND: Large-scale partial sequencing of cDNA libraries to generate expressed sequence tags (ESTs) is an effective means of discovering novel genes and characterizing transcription patterns in different tissues. To catalogue the identities and expression levels of genes in the cardiovascular system, we initiated large-scale sequencing and analysis of human cardiac cDNA libraries. METHODS AND RESULTS: Using automated DNA sequencing, we generated 43,285 ESTs from human heart cDNA libraries. An additional 41,619 ESTs were retrieved from public databases, for a total of 84,904 ESTs representing more than 26 million nucleotides of raw cDNA sequence data from 13 independent cardiovascular system-based cDNA libraries. Of these, 55% matched to known genes in the Genbank/EMBL/DDBJ databases, 33% matched only to other ESTs, and 12% did not match to any known sequences (designated cardiovascular system-based ESTs, or CVbESTs). ESTs that matched to known genes were classified according to function, allowing for detection of differences in general transcription patterns between various tissues and developmental stages of the cardiovascular system. In silico Northern analysis of known gene matches identified widely expressed cardiovascular genes as well as genes putatively exhibiting greater tissue specificity or developmental stage specificity. More detailed analysis identified 48 genes potentially overexpressed in cardiac hypertrophy, at least 10 of which were previously documented as differentially expressed. Computer-based chromosomal localizations of 1048 cardiac ESTs were performed to further assist in the search for disease-related genes. CONCLUSIONS: These data represent the most extensive compilation of cardiovascular gene expression information to date. They further demonstrate the untapped potential of genome research for investigating questions related to cardiovascular biology and represent a first-generation genome-based resource for molecular cardiovascular medicine.

Blotting, Northern↗
PubMed1997

Intramural coronary artery disease in swine with naturally occurring hypertrophic cardiomyopathy.

Intramural coronary artery disease (ICAD) has been reported in myocardium affected with hypertrophic cardiomyopathy (HCM), but has never been studied in detail with respect to the cell type or lipid infiltration involved in the wall-thickening. The lack of heart samples may be one of the rationales to hamper the progress in investigating this disease. Recently, the discovery of naturally occurring HCM in swine has provided an excellent opportunity for the study of ICAD because of the high prevalence of ICAD in this animal. The present study provides a detailed structure feature in the thickened arterial wall of ICAD by both histologic and electron microscopic means. Morphologically, the feature of ICAD is due primarily to the neointimal thickening. Smooth muscle cells (SMC) and extracellular matrix (collagen and elastic fibers) are the major components responsible for the thickened neointima. Fragmentation of the internal elastic membrane is associated with the migration and proliferation of SMC from the media to the intima. Therefore, pigs with HCM may be a potential animal model not only for the study of the mechanism by which SMC migrate and proliferate into intima, but also for the future investigation of interventions in coronary artery occlusion.

Animals↗
PubMed1996

Ultrastructural alterations in pigs with naturally occurring hypertrophic cardiomyopathy.

Naturally occurring hypertrophic cardiomyopathy (HCM) in pigs in generally characterized by unexplained cardiac hypertrophy with abnormal histological features (Liu et al., 1994; Dai et al., 1995). The histological alterations in HCM-affected hearts are characteristic, and can be used to diagnose the disease (Dai et al., 1995). Briefly, these are marked disorientation of cardiac muscle cells, thickening of the intramural coronary arterial wall with a narrowing of the lumen, endocardial and myocardial fibrosis. A high incidence of HCM in a population of pigs strongly suggests a hereditary basis and the Pig Research Institute, Taiwan has, therefore, endeavoured to produce a specific strain of HCM pigs. The purpose of the present study was to determine the ultrastructural changes occurring in pigs with naturally occurring HCM.

Animals↗
PubMed1996

Collagen in naturally occurring hypertrophied porcine myocardium.

A comparison of the collagen network in three dimensions was conducted in 8 hypertrophic cardiomyopathy (HCM)-affected and 8 normal hearts. All these hearts were obtained from male and age-matched pigs of the same breeding farm under identical feeding conditions. The selection of HCM-affected heart was based on the abnormal histologic features such as marked disorientation of muscle cells, thickening of the intramural coronary arterial wall with a narrowed lumen, endocardial fibrosis, and myocardial fibrosis. Mean values of heart weight and ratio of heart to body weight of HCM group were significantly (p < 0.01) increased by 36% and 47%, respectively, but not the body weight, as compared to those of the normal group. The scanning electron microscopic (SEM) investigation demonstrated that collagen weave, struts, and strands appeared more numerous in HCM-affected myocardium than in normals. Moreover, the tendons of collagen in HCM-affected myocardium showed increases in both numbers and thickness.

Animals↗
PubMed1995

Altered adenosine triphosphatase activities in pigs with naturally occurring hypertrophic cardiomyopathy.

The purpose of this study was to determine whether myocardial adenosine triphosphatase (ATPase) activities were reduced in pigs with naturally occurring hypertrophic cardiomyopathy (HCM). The selection of hearts for the HCM and the normal control groups depended on histological examination. Specific ATPase activity and 5'-nucleotidase activity were measured in left ventricular myocardium obtained from HCM (n = 7) and normal control (n = 7) animals. The histological features of HCM included marked disorientation of muscle cells, thickening of the intramural coronary arterial wall with a narrowed lumen, endocardial fibrosis and myocardial fibrosis. The HCM group showed significant increases in both heart weight (32%) and heart weight to body weight ratio (46%). The total ATPase activity in crude homogenates from the HCM group was significantly decreased by 16%. Azide-sensitive ATPase (mitochondrial ATPase) activity, ouabain-sensitive ATPase (Na+, K+-ATPase) activity, basal Mg(2+)-ATPase activity and Ca(2+)-ATPase activity were all significantly decreased by 18%, 30%, 20% and 50%, respectively. In contrast, no significant decrease was found in the mean values for 5'-nucleotidase activity. These results suggest that myocardial ATPase activities are suppressed in pigs with naturally occurring HCM.

5'-Nucleotidase↗
PubMed1991

Ro 5-4864, like picrotoxin, enhances EPSP-spike coupling in the freely behaving rat.

To help determine its mechanism of action, the convulsant benzodiazepine Ro 5-4864 was administered (15-20 mg/kg) intraperitoneally (IP) and electrophysiological and behavioral effects were compared; parallel studies were conducted with picrotoxin (PTX; 1 mg/kg). Both PTX and Ro 5-4864 produced myoclonic seizures, primarily between 15-40 min after administration; myoclonus was followed by more severe seizures after PTX. Both Ro 5-4864 and PTX produced a maximal increase in amplitude and decrease in threshold of the population spike (PS) evoked in the dentate gyrus (DG) by stimulation of the dorsal perforant path prior to peak seizure activity; start latency of the PS and initial slope and amplitude of the population slow wave (SW) were not changed. Amplitude of the PS was already increased by 5 min after administration of Ro 5-4864 and was maximally increased 1.8- to 3-fold, depending on stimulus intensity, usually by 10 min. Similarly, by 20 min after administration, PTX had also increased PS amplitude in the absence of an effect on PS latency or the SW. The increase in PS amplitude without concomitant changes in the SW suggests that Ro 5-4864 enhanced coupling between the excitatory postsynaptic potential (EPSP) and firing of the postsynaptic neurons, i.e., it enhanced E-S coupling, as has also been suggested for PTX. The similarity in the effects of Ro 5-4864 and PTX suggests that antiGABAergic effects, perhaps along feedforward inhibitory pathways, are involved in both the seizures and enhanced E-S coupling.

Animals↗
PubMed1989

Gastric xanthelasma.

Gastric xanthelasmas are macroscopically well demarcated yellow or yellow-white plaques, and microscopically composed of typical foamy macrophages. Of 3870 patients who underwent upper gastrointestinal panendoscopic examinations, 30 (0.8%) were found to have gastric xanthelasma. A moderate predominance of males over females (M:F = 3.3:1) was noted. The age ranged between 21 and 69 years (mean 46.7). Frequency peaked in those from 40 to 60 years of age (53.3%). Single lesions were found in 26 patients and multiple in 4, with diameters of 1-6 mm, nearly 66.7% of which were 2-3 mm. Gastric xanthelasmas are most frequently found in the antrum (67.8%), especially along the lesser curvature. Associated chronic gastritis in the xanthelasma surrounding mucosa was found in the 30 patients and intestinal metaplasia in 4 (13.3%). The cause of gastric xanthelasma is unknown, but chronic gastritis may be the most plausible etiologic factor.

Adult↗