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K S Chang

Publications and source records attributed to K S Chang.

At least 127 records · Page 7Linked to original sources
PubMed1988

The role of v-mos in transformation, oncogenicity, and metastatic potential of mink lung cells.

A cloned line of S + L- mink lung cells (A clone), which exhibited a flat morphology, was superinfected with a novel dual-tropic virus (E1BX-MuLV) showing a broad host range and a B-tropism. These cells gave rise to transformed cells with two phenotypes: those which were still anchorage-dependent (AD), and those which readily detached spontaneously from the substratum and grew in suspension. A clone of these AD cells (B clone) was isolated and compared with a clone of the anchorage-independent suspension-cultured (AISC) cells (C clone). While the C clone exhibited a high oncogenicity and ability to metastasize in nude mice, the A and B clones were not tumorigenic. The integrated v-mos was greatly amplified in the C clone, and moderately increased in the B clone as compared with the A clone. The amounts of v-mos mRNA expressed by B and C clones paralleled those of v-mos sequence in their chromosomal DNA, whereas there was no detectable v-mos mRNA in the A clone. Thus, conversion of S + L- mink cells from an AD growth to an AISC phenotype accompanied by manifestation of oncogenicity and metastatic potential in nude mice is associated with amplification of integrated v-mos gene and its enhanced expression. Furthermore, a revertant (D clone) showing AD phenotype was derived from the C clone by selective growth in ouabain. This revertant exhibited a markedly decreased oncogenicity in nude mice, although the copy numbers of integrated v-mos gene and its mRNA did not differ from those of the parent C clone. While more p37mos protein was found in the C than in the D clone, it was not detectable in the A and B clone. The amounts of helper virus-related mRNA and infectious E1BX-MuLV were markedly higher in the B than in the C and D clones. It is concluded that v-mos gene amplification and overexpression is necessary for these cells to exhibit oncogenicity, but other factors associated with ouabain-resistance can modify or suppress its oncogenicity despite the v-mos amplification and mRNA overexpression.

Animals↗
PubMed1988

Phenotypic and molecular heterogeneity in Philadelphia chromosome-positive acute leukemia.

Philadelphia chromosome-positive (Ph1) acute leukemia is a heterogeneous subset of acute leukemia with a poor prognosis. We studied five patients to determine the potential for phenotypic and molecular heterogeneity. Cellular characterization studies included light myeloperoxidase (L-MPO), terminal deoxynucleotidyl transferase (TdT), ultrastructural MPO (U-MPO), and immunophenotyping by flow cytometry using T11, T3, T4, T8, Leu 1, B1, Leu 12, HLA-DR (la), CALLA (J5), OKM1, My4, My7, My8, My9, and My10. DNA was analyzed for rearrangements of the breakpoint cluster region (bcr), immunoglobulin heavy chain, joining region (JH), immunoglobulin kappa light chain constant region (C kappa), and T cell receptor (TcR beta). RNA dot blots were hybridized by using molecular probes for MPO and TdT. We found that four of five cases were acute mixed-lineage leukemia (AMLL). One patient had acute unclassifiable leukemia. Of the four patients classified as having AMLL, three showed myeloid and lymphoid features, with one patient showing myeloid, T cell, and B cell features. The last case showed T cell and B cell features only. In one patient MPO/RNA was positive in spite of insufficient L-MPO or U-MPO to diagnose acute myelogenous leukemia (AML), thereby suggesting significant MPO gene expression before the production of sufficient MPO protein to meet the French-American-British criteria for AML. Three of the five patients showed rearrangement of bcr (cases 1, 2, and 5). Studies of these five patients support the concepts of molecular and phenotypic heterogeneity in Ph1 acute leukemia, demonstrate a high incidence of AMLL in this subset of acute leukemia, and support the use of lineage-associated molecular probes to define lineage at an earlier stage than previously possible.

Acute Disease↗
PubMed1987

Amplification and enhanced expression of the c-Ki-ras2 protooncogene in human embryonal carcinomas.

Two cell lines of human embryonal carcinoma, Tera-1 and Tera-2, have been found to exhibit a 4- to 6-fold amplification of protooncogene c-Ki-ras2. The polyadenylic acid selected RNA also showed 8-fold or greater enhancement, showing marked elevation in the level of two major mRNAs, 5.7 and 4.0 kilobases, and two additional minor mRNAs, 2.3 and 1.2 kilobases, as compared with those of a normal human embryonic fibroblast cell line, MRC-5. More than one-half of the number of tumor samples obtained from metastatic human embryonal carcinomas also showed c-Ki-ras2 gene amplification and enhanced mRNA expression. However, the c-Ki-ras2 gene amplification did not always lead to enhanced mRNA expression, and some embryonal carcinomas showed mRNA overexpression without apparent c-Ki-ras2 gene amplification. These results suggest that human embryonal carcinomas may have c-Ki-ras2 amplification and/or overexpression before in vitro culture. Among various chromosomal changes observed in Tera-1 and Tera-2 cells, there were anomalies in chromosome 12 in which c-Ki-ras2 is located although these karyological changes alone could not account for the amplification observed. It is suggested that the genomic instability and active DNA replication during the early developmental period may give rise to changes involving c-Ki-ras2 which may contribute to oncogenic processes.

Aneuploidy↗
PubMed1987

Detection of minimal residual cells carrying the t(14;18) by DNA sequence amplification.

By means of the polymerase chain reaction (PCR) technique, DNA sequences were amplified that flank the crossover sites of a characteristic chromosomal translocation for follicular lymphomas, t(14;18)(q32;q21). This technique permitted the detection of cells carrying the t(14;18) hybrid DNA sequences at a dilution of 1:100,000. The remission marrow and blood samples of a patient with follicular lymphoma and the t(14;18) failed to show any abnormality by morphological examination and conventional Southern blot analysis. However, the t(14;18) hybrid DNA sequences were detected by the PCR technique. Thus, this technique is a highly sensitive tool to detect minimal residual cells carrying the t(14;18) and has the potential to identify a subpopulation of patients with subclinical disease.

Base Sequence↗
PubMed1987

The localization of the human myeloperoxidase gene is in close proximity to the translocation breakpoint in acute promyelocytic leukemia.

The human myeloperoxidase (MPO) gene has recently been cloned in our laboratory. Southern blot hybridization of our MPO cDNA to DNA from a somatic cell hybrid clone panel revealed that the MPO cosegregated with human chromosome 17. In situ hybridization mapped the MPO gene to chromosome 17q22-24. Although this location is close to the translocation breakpoint which occurs in acute promyelocytic leukemia (APL), t(15;17)(q22;q21-22), Southern blot hybridization with different restriction-digested genomic DNA samples from four APL patients did not reveal MPO gene rearrangement. However, RNA dot-blot hybridization showed that APL patients with the translocation expressed high levels of MPO mRNA. This observation raises the possibility that the high levels of MPO gene expression in APL could be due to the arrest of leukemic cells at a specific stage of differentiation or a consequence of the translocation.

Chromosome Mapping↗
PubMed1987

T-cell receptor gamma chain gene rearrangement in acute myelogenous leukemia--evidence for lymphoid lineage prematurity.

The T-cell receptor gamma chain (TcR gamma) gene is rearranged in early T-cell differentiation. However, rearrangement of the TcR gamma gene is not specific for T lineage since it has also been noted in B-cell neoplasia. TcR beta gene rearrangement and heavy chain immunoglobulin gene rearrangement have also been reported in acute myelogenous leukemia (AML). Because of the previous reports of lineage heterogeneity at the molecular level, we analyzed seven patients who met the standard criteria for AML by Southern blot hybridization with a TcR gamma gene probe, a TcR beta gene probe, and an immunoglobulin heavy chain JH gene probe. In two samples, the TcR gamma gene was rearranged. One of these two samples also had rearrangement of the immunoglobulin JH gene. None of the seven samples showed TcR beta gene rearrangement. The two samples with TcR gamma gene rearrangement also showed 25% and 80% of terminal deoxynucleotidyl transferase (TdT) positivity, respectively. Both samples expressed myeloid lineage-associated antigens without any lymphoid lineage-associated antigens. Our studies indicate that TcR gamma gene rearrangement is not specific for lymphoid lineage and the presence of TcR gamma and immunoglobulin JH gene rearrangements without expression of lymphoid lineage-associated markers supports the concept that there is lymphoid lineage prematurity in AML.

Gene Rearrangement, gamma-Chain T-Cell Antigen Rec↗
PubMed1986

Alterations in the baroreceptor reflex control of heart rate in streptozotocin diabetic rats.

Baroreflex control of heart rate was studied in conscious diabetic rats at 12, 24 and 48 weeks after the induction of diabetes with streptozotocin. Baseline blood pressure (mean arterial blood pressure) of diabetic rats was significantly lower at 12 weeks after the induction of diabetes when compared to age-matched control rats. However, at 24 and 48 weeks of diabetes, no difference in blood pressure was observed between diabetic and age-matched control rats. In contrast, bradycardia (prolongation of pulse interval) was a consistent feature of diabetic rats at all time points (12, 24, and 48 weeks). To assess parasympathetic control of heart rate, baroreceptor sensitivity was determined by infusing phenylephrine. Baroreflexes in diabetic rats were changed from an increased sensitivity at 12 and 24 weeks to decreased sensitivity at 48 weeks after the induction of diabetes. This suggests that alterations in baroreflex sensitivity might depend upon the length of time the animals were exposed to the diabetes. Insulin treatment in diabetic animals reversed hypotension, bradycardia and altered baroreflex sensitivity observed in 12-week diabetic rats. Non-diabetic rats, in which the development of diabetes was prevented by pretreatment with 3-0-methylglucose before streptozotocin injection, or rats which did not develop diabetes after streptozotocin injection showed a similar baseline blood pressure, heart rate and baroreflex sensitivity to those of age-matched control rats (12, 24 and 48 weeks). This data suggests that changes in blood pressure, heart rate and baroreflex sensitivity are due to the diabetic state, not to streptozotocin toxicity.

Animals↗
PubMed1986

Human myeloperoxidase gene: molecular cloning and expression in leukemic cells.

We have molecularly cloned the human myeloperoxidase (MPO) gene from the lambda gt11 expression library by screening with an affinity-purified MPO antibody. The cDNA clone of the MPO gene was used to study MPO gene expression in leukemic cells. The amino acid sequence predicted from the nucleotide sequence of the cDNA clone pMP401 matched exactly the 23 amino acid sequence of the NH2-terminal of the 60,000 MPO subunit. We found that MPO cDNA hybridized to a single EcoRI genomic band of 19 kb, indicating that the MPO gene represents a single gene in the human genome. Northern blot analysis of RNA isolated from leukemic cell lines and acute myelogenous leukemia (AML) patients' samples shows that MPO gene expression correlated with myeloid lineage. The intensity of MPO mRNA expression on Northern blot correlated with the level of MPO expression by cytochemical staining. Multiple species of MPO mRNA were found. This indicates that a single MPO gene may encode different RNA species through a mechanism of posttranscriptional processing or that multiple transcriptional start/termination sites exist in the MPO gene.

Amino Acid Sequence↗
PubMed1985

The complete sequence of the chicken alpha-cardiac actin gene: a highly conserved vertebrate gene.

We sequenced the entire chicken alpha-cardiac actin gene. A single intron was positioned 20 bp upstream from the initiation ATG codon in the 5' non-coding region while the coding region was interrupted by 5 introns at amino acid positions 41/42, 150, 204, 267, and 327/328. Sequencing allowed the first comparison of the alpha-cardiac and alpha-skeletal actin transcriptional promoters. These highly G+C rich promoters share two regions of homology which are found at position -134 (10 bp) and -296 (12 bp) in the alpha-cardiac actin promoter. A smaller 9 bp motif (CCGCGCCGG) homologous to the -134 sequence was detected before, between and after the TATA and CAAT boxes of the alpha-cardiac actin gene. The polyadenylation signal (AATAAA) was located 156 bp downstream from the translation termination codon. The complete length of the alpha-cardiac actin mRNA excluding the poly A tail is 1370 nucleotides. The 3' noncoding transcribed portion of the chicken alpha-cardiac actin gene was found to be extraordinarily conserved when compared to the human and rat alpha-cardiac actin mRNA sequences.

Actins↗
PubMed1985

Novel chicken actin gene: third cytoplasmic isoform.

We identified a novel chicken actin gene. The actin protein deduced from its nucleotide sequence very closely resembles the vertebrate cytoplasmic actins; accordingly, we classified this gene as a nonmuscle type. We adopted the convention for indicating the nonmuscle actins of the class Amphibia (Vandekerckhove et al., J. Mol. Biol. 152:413-426) and denoted this gene as type 5. RNA blot analysis demonstrated that the type 5 actin mRNA transcripts accumulate in adult tissues in a pattern indicative of a nonmuscle actin gene. Genomic DNA blots indicated that the type 5 actin is a single copy gene and a distinct member of the chicken actin multigene family. Inspection of the nucleotide sequence revealed many features that distinguished the type 5 gene from all other vertebrate actin genes examined to date. These unique characteristics include: (i) an initiation Met codon preceding an Ala codon, a feature previously known only in plant actins, (ii) a single intron within the 5' untranslated region, with no interruptions in the coding portion of the gene, and (iii) an atypical Goldberg-Hogness box (ATAGAA) preceding the mRNA initiation terminus. These unusual features have interesting implications for actin gene diversification during evolution.

Actins↗
PubMed1984

Calorimetrical comparison of insulative properties of metalized plastic, clear polyethylene, and polyester blanket.

The thermal insulation properties of metalized plastic sheeting (MPS), clear polyethylene sheeting (CPS) and 100 per cent polyester thermal bed blanket (TBB) were tested and compared quantitatively using direct calorimetry. The experiments were carried out on individual subjects sitting in a whole body calorimeter and covered first with a TBB bag up to the neck. Then the three materials were tested, one at a time, over the original TBB up to the neck. The temperature of the calorimeter was set at normal operating room temperature of 18 degrees C. MPS provided the greatest reduction in sensible heat loss (SHL) of all three materials tested. The total SHL saving provided by an MPS over TBB was 29.7 per cent and was statistically highly significantly different from that provided by a CPS or TBB over TBB (the difference is 9.6 and 9.9 per cent, respectively, p less than 0.001 for both). While the SHL saving provided by a CPS over TBB was 20.1 per cent, and a TBB over TBB was 19.8 percent, the difference of 0.3 per cent is statistically not significant (p greater than 0.5). An additional finding was that MPS is electrically conductive on one side. Precautions must be taken when it is used on patients connected to electrical devices. Also, insensible perspiration trapped inside the bag can be as much as 10 g X hour-1 and may become a problem when the patient is wrapped in MPS for an extended period of time.

Body Temperature Regulation↗
PubMed1984

Demonstration of a problem in estimating sensible heat loss from the respiratory tract by thermometry.

We have investigated sensible respiratory loss, which is usually taken as the product of expired volume and the temperature difference between inspired and expired air (VE X delta T). Air temperature was measured with a 0.122 mm copper-constantan thermocouple mounted in the mouthpiece of a T-piece breathing system, and expired volume with a pneumotachograph. Changing air temperature (delta T) at the mouth and expired air volume (VE) were recorded simultaneously while the subject voluntarily breathed at different tidal volumes and rates. Inspired temperatures were controlled at 12.05 degrees C, 21.80 degrees C and 25.74 degrees C at a low dewpoint temperature of 4-5 degrees C. Temperature volume "loops" were constructed using an x-y plotter. The areas of each "loop" and enclosing rectangle (VE X delta T) were measured. The difference was divided by the weight of the rectangle to give the percentage of overestimation of sensible heat loss, which ranged from 5.5 to 17.2 per cent. The error increased significantly with decreasing tidal volume and increasing respiratory rate.

Body Temperature Regulation↗
PubMed1984

Isolation and characterization of six different chicken actin genes.

Genes representing six different actin isoforms were isolated from a chicken genomic library. Cloned actin cDNAs as well as tissue-specific mRNAs enriched in different actin species were used as hybridization probes to group individual actin genomic clones by their relative thermal stability. Restriction maps showed that these actin genes were derived from separate and nonoverlapping regions of genomic DNA. Of the six isolated genes, five included sequences from both the 5' and 3' ends of the actin-coding area. Amino acid sequence analysis from both the NH2- and COOH-terminal regions provided for the unequivocal identification of these genes. The striated isoforms were represented by the isolated alpha-skeletal, alpha-cardiac, and alpha-smooth muscle actin genes. The nonmuscle isoforms included the beta-cytoplasmic actin gene and an actin gene fragment which lacked the 5' coding and flanking sequence; presumably, this region of DNA was removed from this gene during construction of the genomic library. Unexpectedly, a third nonmuscle chicken actin gene was found which resembled the amphibian type 5 actin isoform (J. Vandekerckhove, W. W. Franke, and K. Weber, J. Mol. Biol., 152:413-426). This nonmuscle actin type has not been previously detected in warm-blooded vertebrates. We showed that interspersed, repeated DNA sequences closely flanked the alpha-skeletal, alpha-cardiac, beta-, and type 5-like actin genes. The repeated DNA sequences which surround the alpha-skeletal actin-coding regions were not related to repetitious DNA located on the other actin genes. Analysis of genomic DNA blots showed that the chicken actin multigene family was represented by 8 to 10 separate coding loci. The six isolated actin genes corresponded to 7 of 11 genomic EcoRI fragments. Only the alpha-smooth muscle actin gene was shown to be split by an EcoRI site. Thus, in the chicken genome each actin isoform appeared to be encoded by a single gene.

Actins↗
PubMed1983

Control of H-2 antigen and beta 2-microglobulin gene expression in mouse trophoblast cell clones.

We have investigated the expression of H-2 antigen and beta 2-microglobulin in recently established mouse trophoblast cell clones. These clones, derived from C57BL/6 (H-2b) or BALB/c (H-2d) strains, synthesized extra-embryonic endoderm- and trophectoderm-specific cytoskeletal proteins, termed "Endo A" and "Endo B," and no detectable SSEA-1 embryonic antigen. Flow microfluorometry indicated that H-2 antigen expression on the cell surface of trophoblast cells was very low, corresponding to 2-5% of the amounts found on differentiated teratocarcinoma cells (12-1a) and BALB/c 3T3 cells, respectively. Expression of beta 2-microglobulin was reduced to approximately equal to 14% of the amounts found on 12-la cells. Immunoprecipitation and polyacrylamide gel electrophoretic analysis indicated that the synthesis of H-2 antigen and beta 2-microglobulin in the trophoblast cells was lower than that found in normal spleen cells. In addition low, but unequal, levels of mRNA specific for H-2 antigen and beta 2-microglobulin were found in trophoblast cells by blot hybridization with cDNA probes. The low mRNA levels may be due to transcriptional control of the genes encoding H-2 antigen and beta 2-microglobulin.

Animals↗