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T S Wan

Publications and source records attributed to T S Wan.

At least 37 records · Page 2Linked to original sources
PubMed2000

Establishment and characterization of HKESC-1, a new cancer cell line from human esophageal squamous cell carcinoma.

The establishment of an esophageal cancer cell line can facilitate the search for molecular mechanisms involved in esophageal carcinogenesis. A new human cancer cell line, HKESC-1, was established from a primary moderately-differentiated squamous cell carcinoma of the esophagus from a 47-year-old Hong Kong Chinese man. The pathological characteristics (morphology, immunohistochemical, and electron microscopic studies), the tumorigenecity in nude mice, the cytogenetic features, the DNA ploidy, and telomerase activity of the cell line were investigated. The HKESC-1 cells have been maintained continuously in vitro for more than 16 months and passaged over 96 times. HKESC-1 cells grow as a monolayer, with a doubling time of 46 hours. The HKESC-1 cells are of a squamous epithelial origin, as shown by their immunopositivity with the anti-cytokeratin antibodies and ultrastructural demonstration of tonofilaments and desmosomes. The HKESC-1 cells possess characteristics of malignancy because they are highly tumorigenic in nude mice and have strong telomerase activity. The HKESC-1 cells had an aneuploid DNA content, as demonstrated by flow cytometric analysis. Cytogenetic analysis revealed hyperdiploidy of greater than 50 in 80% of analyzable metaphases. Chromosome gains and losses were common, and loss of the Y chromosome was a consistent numerical aberration. Additionally, many structural chromosomal abnormalities were encountered, with frequent breakpoints at 1p32, 7p22, 7q34, and 20q13. This newly established cell line serves as a useful model for studying the molecular pathogenesis, and testing new therapeutic reagents for esophageal squamous cell carcinoma.

Animals↗
PubMed2000

Complex cytogenetic abnormalities in T-lymphoblastic lymphoma: resolution by spectral karyotyping.

We describe a case of T-lymphoblastic lymphoma (T-LBL) in a 13-year-old boy in which conventional cytogenetic analysis of lymph node tissue showed complex karyotypic aberrations including add(1p), add(2q), and multiple chromosomal deletions involving 5q, 7p, 7q, 13q, and 16q. Analysis by spectral karyotyping (SKY) refined add(1p) to a paracentric inversion of 1p, and add(2q) to an unbalanced translocation between chromosomes 2 and 4. The chromosomal deletions were simple deletions except del(5q), which was confirmed by SKY to be a cryptic unbalanced translocation between chromosomes 5 and 18. The present report illustrates that SKY technology is useful in identifying subtle translocations and resolving complex karyotypic aberrations in neoplastic disorders.

Adolescent↗
PubMed2000

Differentiation of enantiomers using matrix-assisted laser desorption/ionization mass spectrometry.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has successfully been used to differentiate pseudo-enantiomeric (isotopically labelled) amino acids by using cyclodextrin as complexing host. By using different pseudo-enantiomeric mixtures (i.e. R(Dn) + S; and R + S(Dn)), it has been demonstrated that the preference of cyclodextrin for S-enantiomers is not due to the size differences caused by the hydrogen/deuterium substitution. It is postulated that this method can be extended to differentiate enantiomers (and determine enantiomeric excess) by using a pair of enantiomeric hosts, as demonstrated previously using other ionization techniques, but with much higher sensitivity.

Amino Acids↗
PubMed2000

Molecular characterization of der(15)t(11;15) as a secondary cytogenetic abnormality in acute promyelocytic leukemia with cryptic PML-RAR alpha fusion on 17q.

A case of acute promyelocytic leukemia (APL) with cryptic PML-RAR alpha fusion on 17q and add(15p) as a secondary abnormality was characterized using molecular cytogenetic techniques. Spectral karyotyping (SKY) showed that chromosome 11 material was added to 15p, forming a der(15)t(11;15), which was refined to der(15)t(11;15)(q13.2;p13) with information obtained by comparative genomic hybridization (CGH). Interstitial insertion of chromosome 15 material into chromosome 17q was found by fluorescence in situ hybridization (FISH) with whole chromosome painting (WCP) probes. This study illustrates the necessity of a combination of molecular cytogenetics to decipher complex karyotypic abnormalities and cryptic translocations in leukemia.

Chromosomes, Human, Pair 11↗
PubMed2000

Analysis of MLL-derived transcripts in infant acute monocytic leukemia with a complex translocation (1;11;4)(q21;q23;p16).

It has been proposed, on the basis of cytogenetic studies and molecular analysis of MLL-derived transcripts in acute leukemia with 11q23 rearrangement, that only one fusion gene transcript present on the der(11) chromosome is critical for leukemogenesis. This view is challenged by a recent observation in a case of leukemia with a complex translocation that results in MLL being fused in-frame to two different partner genes. We investigated a case of infant monocytic leukemia with a complex translocation, (1;11;4)(q21;q23;p16). Molecular studies revealed MLL rearrangement by both fluorescence in situ hybridization and Southern blot analysis, and MLL/AF1q, but not the reciprocal message (i.e., AF1q/MLL), was amplified by polymerase chain reaction. Sequence analysis of MLL/AF1q revealed an in-frame fusion between MLL exon 6 and the breakpoint located six bases upstream of the ATG start site for AF1q. Our data suggest that only one form of MLL fusion gene is implicated in leukemogenesis in our case to t(1;11;4).

Base Sequence↗
PubMed2000

Cytogenetic characterization of childhood hepatoblastoma.

We describe the cytogenetic abnormalities in two cases of childhood hepatoblastoma. The first case was of fetal histology with squamous metaplasia, and cytogenetic study showed an add(5)(q31). Although an association between hepatoblastoma and familial adenomatous polyposis is recognized, the breakpoint in this case is distal to 5q21 and most probably does not involve the APC gene at that location. The second case was of macrotrabecular histology, and cytogenetic study showed an unbalanced translocation in the form of der(4)t(1;4)(q12;q34) in a hyperdiploid clone. Including our case, der(4)t(1;4)(q12;q34) has been recognized in four cases of hepatoblastoma, and it may be the first recurrent translocation in this tumor. Understanding the molecular mechanism and clinical significance of this translocation awaits analysis of more cases.

Child, Preschool↗
PubMed2000

Graft-versus-host disease after liver transplantation: documentation by fluorescent in situ hybridisation and human leucocyte antigen typing.

Graft-versus-host disease (GVHD) after liver transplantation is uncommon and the outcome is often fatal. A firm diagnosis of GVHD is difficult because the clinical triad of skin rash, marrow failure and diarrhoea can be indistinguishable from drug reaction or viral infection, and the presence of donor lymphocyte chimerism is not specific. We describe a case of severe GVHD in a female patient after liver transplantation from a male cadaveric donor. Skin biopsy showed characteristic changes of GVHD. Using Y-chromosome-specific fluorescent in situ hybridisation (FISH), male lymphocytes were demonstrated in 10% of marrow cells and in 90% of lymphocytes infiltrating the dermal epidermal junction. Donor human leucocyte antigens (HLAs) were detected in the peripheral blood, buccal mucosa and skin by polymerase chain reaction. The GVHD subsided with steroid and anti-thymocyte globulin, but recurred on tailing off of treatment. Despite maximum supportive therapy, including random donor leucocyte infusion, and marrow infusion from a HLA-identical sibling, the patient succumbed to sepsis. Our results showed the utility of combining morphological features with molecular techniques using FISH and HLA typing in confirming a diagnosis of GVHD.

Adult↗
PubMed2000

Acute myeloid leukaemia with giant granules: association with t(10; 11)(p13; q14) and disseminated intravascular coagulation.

A 16-year-old Chinese girl presented with AML-M5a. A bone marrow examination showed that the myeloblasts which were overwhelming the marrow contained giant granules (pseudo-Chediak-Higashi anomaly). Her karyotype showed a rare translocation t(10; 11)(p13; q14). Molecular delineation of the translocation breakpoints was not possible. Nonetheless, this case further demonstrates the morphological and phenotypic heterogeneity of acute leukaemia with this translocation. In this girl it was associated with disseminated intravascular coagulation.

Adolescent↗
PubMed2000

Absence of microsatellite instability in primary myelodysplastic syndrome.

Using polymerase chain reaction (PCR), we examined a panel of 10 microsatellite markers (BAT26, BAT40, D2S123, D4S171, D8S87, D10S197, D12S89, Tp53, D18S58, PLCpr) covering nine chromosomal arms for microsatellite instability (MSI) in 29 patients with primary MDS. Bone marrow DNA was compared with corresponding constitutional DNA derived from buccal epithelial cells. Apart from BAT26 and BAT40 that were mononucleotide (poly A) repeats, the others were dinucleotide (CA) repeats. The patients comprised 10 cases of refractory anemia (RA), three cases of refractory anemia with ringed sideroblasts (RARS), nine cases of refractory anemia with excess of blasts (RAEB), four cases of refractory anemia with excess of blasts in transformation (RAEBt), and three cases of chronic myelomonocytic leukemia (CMML). Serial samples were available in seven patients, in which four showed transformation into higher disease grade or acute myeloid leukemia (AML). Genetic alterations at one locus (three at D2S123, one at D4S171) were evident in four cases, and loss of heterozygosity at Tp53 was detected in one case. Accordingly, none of the 29 patients with primary MDS nor the seven with disease progression in this study exhibited MSI. This shows that MSI may not be important in the pathogenesis or progression of MDS in contrast to other genetic mechanisms, notably recurrent chromosomal abnormalities that dysregulate the expression or function of genes controlling cell growth, differentiation and apoptosis.

Aged↗
PubMed1999

Simultaneous determination of artemether and its major metabolite dihydroartemisinin in plasma by gas chromatography-mass spectrometry-selected ion monitoring.

A sensitive, selective, and reproducible GC-MS-SIM method was developed for determination of artemether (ARM) and dihydroartemisinin (DHA) in plasma using artemisinin (ART) as internal standard. Solid phase extraction was performed using C18 Bond Elut cartridges. The analysis was carried out using a HP-5MS 5% phenylmethylsiloxane capillary column. The recoveries of ARM, DHA and ART were 94.9 +/- 1.6%, 92.2 +/- 4.1% and 81.3 +/- 1.2%, respectively. The limit of quantification in plasma was 5 ng/ml (C.V. < or = 17.4% for ARM and 15.2% for DHA). Calibration curves were linear with R2 > or = 0.988. Within day coefficients of variation were 3-10.4% for ARM and 7.7-14.5% for DHA. Between day coefficients of variations were 6.5-15.4% and 7.6-14.1% for ARM and DHA. The method is currently being used for pharmacokinetic studies. Preliminary data on pharmacokinetics showed Cmax of 245.2 and 35.6 ng/ml reached at 2 and 3 h and AUC0-8 h of 2463.6 and 111.8 ngh/ml for ARM and DHA, respectively.

Adult↗
PubMed1999

Atypical chronic myeloid leukemia with der(20)t(17;20)(q21;q13).

We present a case of atypical chronic myeloid leukemia that developed blastic transformation four months after initial presentation, with the blast cells showing multilineage antigen expression. A novel karyotypic abnormality, der(20)t(17;20)(q21;q13), was found in bone marrow cells at diagnosis. The potential role of such an aberration in leukemogenesis is discussed.

Adult↗
PubMed1999

Absence or low number of telomere repeats at junctions of dicentric chromosomes.

Human ovarian surface epithelial (HOSE) cells transfected with the E6 and E7 oncogenes of the human papilloma virus (PV) do not express measurable telomerase activity. Relative to untransfected control cells, HOSE-PV cells have an extended in vitro lifespan characterized by a very high frequency of telomeric associations (TAs) of chromosomes. In order to study the role of telomere shortening in the formation of TAs, we studied the telomere length in 120 dicentric chromosomes in HOSE-PV cells by using quantitative fluorescence in situ hybridization. Forty percent of the dicentric chromosomes had no fluorescence signal at the junction site, and in the remainder the fluorescence at the junction was less than at corresponding unjoined ends. These observations support a critical role of telomere shortening in the development of TAs and the subsequent genetic instability observed in a majority of tumor cells.

Cells, Cultured↗