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Biomedical subjects

K C Cheng

Publications and source records attributed to K C Cheng.

At least 19 recordsLinked to original sources
PubMed2004

Inhibition of N-acetyltransferase activity and gene expression in human colon cancer cell lines by diallyl sulfide.

Diallyl sulfide (DAS) is one of the major components of garlic (Allium sativum) and is widely used in the world for food. In this study, DAS was selected for testing the inhibition of arylamine N-acetyltransferase (NAT) activity (N-acetylation of 2-aminofluorene) and gene expression (mRNA NAT) in human colon cancer cell lines (colo 205, colo 320 DM and colo 320 HSR). The NAT activity was examined by high performance liquid chromatography and indicated that a 24 h DAS treatment decreases N-acetylation of 2-aminofluorene in three colon (colo 205, 320 DM and colo 320 HSR) cancer cell lines. The NAT enzymes (protein) were analyzed by western blotting and flow cytometry and it indicated that DAS decreased the levels of NAT in three colon (colo 205, 320 DM and colo 320 HSR) cancer cell lines. The gene expression of NAT (mRNAT NAT) was determined by polymerase chain reaction (PCR), it was shown that DAS affect mRNA NAT expression in examined human colon cancer cell lines. This report is the first to demonstrate that DAS does inhibit human colon cancer cell NAT activity and gene expression.

Allyl Compounds↗
PubMed2003

Curcumin inhibited the arylamines N-acetyltransferase activity, gene expression and DNA adduct formation in human lung cancer cells (A549).

It is well known that N-acetyltransferase (NAT) plays an important role in the arylamine metabolism. We analysed the response of A549 human lung cancer cells for N-acetylation of 2-aminofluorene (AF) to curcumin. After curcumin treatment, the NAT activity was examined by HPLC, AF-DNA adduct formation was examined by HPLC, and NAT gene expression by polymerase chain reaction were detected. The NAT activity in the human A549 cells and cytosols was suppressed by curcumin in a dose-dependent manner. The results also demonstrated that gene expression (NAT1 mRNA) in human lung A549 tumor cells was inhibited and decreased by curcumin. After the incubation of human lung A549 tumor cells with AF with or without curcumin co-treatment, the cells were recovered and DNA was prepared and hydrolyzed to nucleotides. The adducted nucleotides were extracted into butanol and analyzation of AF-DNA adducts was done by HPLC. The results also demonstrated that curcumin decreases AF-DNA adduct formation in the human lung A549 tumor cells.

Acetylation↗
PubMed2003

Patient effective dose from sentinel lymph node lymphoscintigraphy in breast cancer: a study using a female humanoid phantom and thermoluminescent dosemeters.

The aim of this study was to measure the dose delivered to patients undergoing sentinel lymph node lymphoscintigraphy by taking into account both the transmission scan dose using a (57)Co flood source and the (99)Tc(m) internal emission dose. An adult female humanoid phantom and a set of thermoluminescent dosimeters were used in the measurements. The choice of measurement organs in the humanoid was guided by the recommendations described in the International Commission on Radiological Protection report number 60. A (57)Co flood source was used in external transmission to irradiate the humanoid at posterior, left lateral, left posterior oblique, right lateral and right posterior oblique positions. Four (99)Tc(m) deposits as internal emission sources were used to simulate patient peritumoural injection. The individual effective doses for external transmission and internal emission, normalized to the cumulated activity and expressed in micro Sv(MBq x h)(-1) were then calculated. The effective dose for a transmission scan was on average 0.061 micro Sv(MBq x h)(-1) for each (57)Co flood source position and for internal emission 0.312 micro Sv(MBq x h)(-1) and 0.291 micro Sv(MBq x h)(-1) for left and right breast injection, respectively. Using these results, the effective dose from both transmission and emission sources can be calculated according to the nuclear medicine scanning protocol and surgical procedure of the individual institution. For our protocols, the patient receives a maximum effective dose of 52 micro Sv for the 1 day protocol (18 MBq injection) and 204 micro Sv for the 2 day protocol (74 MBq injection) if only the sentinel lymph node is excised. If other tissues containing radioactivity are removed, the patient effective dose will be reduced by about 50% and 6%, respectively, for the 1 day protocol and 2 day protocol. Although the doses are low compared with other radiological examinations, the results are informative for patients concerned about radiation exposure for this new imaging technique.

Breast Neoplasms↗
PubMed2001

The repertoire of Na,K-ATPase alpha and beta subunit genes expressed in the zebrafish, Danio rerio.

We have identified a cohort of zebrafish expressed sequence tags encoding eight Na,K-ATPase alpha subunits and five beta subunits. Sequence comparisons and phylogenetic analysis indicate that five of the zebrafish alpha subunit genes comprise an alpha1-like gene subfamily and two are orthologs of the mammalian alpha3 subunit gene. The remaining alpha subunit clone is most similar to the mammalian alpha2 subunit. Among the five beta subunit genes, two are orthologs of the mammalian beta1 isoform, one represents a beta2 ortholog, and two are orthologous to the mammalian beta3 subunit. Using zebrafish radiation hybrid and meiotic mapping panels, we determined linkage assignments for each alpha and beta subunit gene. Na,K-ATPase genes are dispersed in the zebrafish genome with the exception of four of the alpha1-like genes, which are tightly clustered on linkage group 1. Comparative mapping studies indicate that most of the zebrafish Na,K-ATPase genes localize to regions of conserved synteny between zebrafish and humans. The expression patterns of Na,K-ATPase alpha and beta subunit genes in zebrafish are quite distinctive. No two alpha or beta subunit genes exhibit the same expression profile. Together, our data imply a very high degree of Na,K-ATPase isoenzyme heterogeneity in zebrafish, with the potential for 40 structurally distinct alpha/beta subunit combinations. Differences in expression patterns of alpha and beta subunits suggest that many of the isoenzymes are also likely to exhibit differences in functional properties within specific cell and tissue types. Our studies form a framework for analyzing structure function relationships for sodium pump isoforms using reverse genetic approaches.

Amino Acid Sequence↗
PubMed2001

Oral administration of collagen conjugated with cholera toxin induces tolerance to type II collagen and suppresses chondritis in an animal model of autoimmune ear disease.

B10.RIII (H-2r) mice were orally administered cyanogen bromide peptide 11 (CB11) or cholera toxin B (CTB)-conjugated CB11 to induce tolerance in collagen-induced autoimmune ear disease. Oral administration of a high dosage of CB11 provided partial protection from chondritis. However, administration of a tiny amount of CTB-CB11 conjugate effectively suppressed chondritis. Oral administration of CTB-CB11 conjugate did not alter the stimulation of T cells in vitro or the fine specificities of B cells. The oral administration of CTB-CB11 caused a higher level of type II collagen-specific IgG and its subclass. Interestingly, increases of TH1 cytokine (interferon-gamma) in Peyer's patches and of TH1/TH2 cytokines (interleukin-2 and interleukin-4) in lymph nodes were detected in mice that had been fed CTB-CB11. An increase of CD8+ T cells in the Peyer's patches with a decrease of CD8+ T cells in lymph nodes was seen in mice that had been fed CTB-CB11. These results suggest that protection from chondritis by oral administration of minute amounts of CTB-CB11 conjugate can be achieved by a mechanism distinct from that of conventional oral tolerance induction.

Administration, Oral↗
PubMed2000

Centromere-linked microsatellite markers for linkage groups 3, 4, 6, 7, 13, and 20 of zebrafish (Danio rerio).

A large number of interesting mutations affecting development and organogenesis have been identified through genetic screens in zebrafish. Mapping of these mutations to a chromosomal region can be rapidly accomplished using half-tetrad analysis. However, knowledge of centromere-linked markers on every chromosome is essential to this mapping method. Centromeres on all 25 linkage groups have been mapped on the RAPD zebrafish genetic map. However, species specificity and the lack of codominance make RAPD markers less practical for mapping than microsatellite-based markers. On the microsatellite-based genetic map, centromere-linked markers have been identified for 19 linkage groups. No direct evidence has been published linking microsatellite markers to the centromeres of linkage groups 3, 4, 6, 7, 13, and 20. Therefore, we compared the microsatellite-based genetic map with the RAPD map to identify markers most likely linked to the centromeres of these 6 linkage groups. These candidate markers were tested for potential centromere linkage using four panels of half-tetrad embryos derived by early-pressure treatment of eggs from four different female zebrafish. We have identified microsatellite markers for linkage groups 3, 4, 6, 7, 13, and 20 to within 1.7 cM of their centromeres. These markers will greatly facilitate the rapid mapping of mutations in zebrafish by half-tetrad analysis.

Animals↗
PubMed2000

Ethylnitrosourea induces neoplasia in zebrafish (Danio rerio).

The zebrafish (Danio rerio) has been successfully used to discover hundreds of genes involved in development and organogenesis. To address the potential of zebrafish as a cancer model, it is important to determine the susceptibility of zebrafish to tumors. Germ line mutations are most commonly induced for zebrafish mutant screens by exposing adult male zebrafish to the alkylating agent, ethylnitrosourea (ENU). To determine whether ENU induces tumors, we compared the incidence of tumors in ENU-treated fish with untreated controls. Interestingly, 18 of 18 (100%) fish mutagenized with either 2.5 or 3.0 mM ENU developed epidermal papillomas, which numbered 1 to 22 per fish, within 1 year of treatment. The induced epidermal lesions included epidermal hyperplasia, flat papillomas (0.2 to 1.2 mm), and pedunculated papillomas (1.2 to 8 mm in greatest dimension), but no skin cancers. Angiogenesis was evident in papillomas larger than approximately 1 mm. All but two papillomas contained the three cell types (keratinocytes, club, and mucous cells) of normal zebrafish epidermis; histologic variants lacked either club cells or mucous cells. Two cavernous hemangiomas and a single malignant peripheral nerve sheath tumor were also found in the treated fish. None of five untreated controls developed tumors. These studies establish the feasibility of the zebrafish as an experimental model for the study of skin tumors.

Animals↗
PubMed2000

Proto-oncogene Raf-1 as an autoantigen in Meniere's disease.

The 28 kd protein extracted from the guinea pig inner ear membranous fraction, which reacted with sera from patients with Meniere's disease, has been subjected to microsequencing. Nineteen amino acids were obtained (IVQQFGFQRRASDDGKLTQ). A protein data bank search showed that this sequence corresponded to residues 41 to 60 of human Raf-1 protein. Sera from 16 of 27 patients with Meniere's disease showed reactivity to the recombinant purified glutathione-S-transferase-Raf-1 protein. These results support the hypothesis that a subgroup of patients who suffer from Meniere's disease, as well as some other kinds of autoimmune inner ear diseases, have an autoantibody against Raf-1 protein.

Amino Acid Sequence↗
PubMed1999

Murine model of autoimmune hearing loss induced by myelin protein P0.

Myelin protein P0 has been identified as an autoantigen in inner ear diseases. In order to study autoimmune hearing loss, we performed brain stem auditory-evoked potential (BAEP) studies on P0-sensitized mice. Two P0-sensitized mice showed hunched posture, poor coat, loss of body weight, and abnormal walking with a waddling gait. About 25% of the P0-sensitized mice developed hearing loss. In the BAEP study, peak latencies of waves I, III, and V and the interpeak latency I-III were prolonged in the P0-sensitized hearing loss group of mice. Hearing thresholds were elevated in this group of mice in comparison with the control mice. Inflammatory cell infiltration was observed in the cochlear nerve region, and a reduced number of spiral ganglion cells was also detected. These results suggest that P0-sensitized mice are a useful model for studying autoimmune inflammation of the peripheral portion of the auditory system.

Animals↗
PubMed1998

House dust mite-induced sensitivity in mice.

Sensitivity induced by house dust mite (HDM) extract in mice was investigated in this study. Sensitized B10.RIII mice (H-2r background) had T-cell proliferative responses to HDM extract in vitro and an HDM-specific IgE response. When mice were immunized by injection and intranasal inhalation with HDM extract, a histologic study showed eosinophils and mononuclear cell infiltration in the lung tissue and bronchial wall. Tcr alphabeta-positive cells were also found in the cell infiltration area of the lung lesions. In the control mice that were immunized by injection or intranasal inhalation (but not both), we did not observe cell accumulation in the lung tissue or in the bronchial wall. Epitope studies suggest that T cells recognize multiple epitopes. Molecular analysis of these HDM-specific T-cell hybridoma clones suggest that T-cell receptor use is restricted to members of the V alpha 8 and Vbeta 6 subfamilies.

Allergens↗
PubMed1998

Transient bone marrow oedema: a variant pattern of sacral insufficiency fractures.

A 71-year-old woman presenting with severe low back pain was found to have a large oval area of increased sacral uptake on Tc-99m MDP scan, with corresponding T1-hypointense and T2-hyperintense areas on magnetic resonance (MR) images, highly suggestive of malignancy. Open biopsies showed only callus formation. The patient responded clinically to conservative measures, with twice-repeated follow-up Tc-99m MDP and MR scans documenting resolution of transient bone marrow oedema. We suggest that this form of marrow oedema represents a variant pattern of sacral insufficiency fractures.

Aged↗
PubMed1998

Successful prevention of retrocochlear hearing loss in murine experimental allergic encephalomyelitis with T cell receptor Vbeta8-specific antibody.

Experimental allergic encephalomyelitis is an animal model of a T cell-mediated autoimmune disease -- for example, multiple sclerosis. We demonstrated that mice with experimental allergic encephalomyelitis developed retrocochlear hearing loss, and that the lesion of the auditory pathway might be related to T cell receptor Vbeta8-expressing T cells. To investigate whether anti-Vbeta8 antibody could prevent hearing loss, we carried out brain stem auditory evoked potential testing, histologic examinations, and flow cytometry in antibody-treated and control myelin basic protein-immunized B10.PL mice. The antibody was administered just before immunization of myelin basic protein. The disease incidence and severity were significantly reduced in the mice injected with the antibody. The results of brain stem auditory evoked potential testing, histologic examinations, and flow cytometry indicated that the depletion of Vbeta8-expressing T cells brings the prevention of hearing loss, as well as prevention of other neurologic deficits. The development of T cell receptor-specific antibody therapy might help treat retrocochlear hearing loss in multiple sclerosis.

Animals↗
PubMed1998

Agarose-embedded tissue arrays for histologic and genetic analysis.

To facilitate the histologic analysis of large numbers of 7-day-old zebrafish (Danio rerio), a method has been developed to process them in agarose-embedded arrays. Using thin tissue sections, the morphology of cells and tissues can be examined microscopically to investigate a variety of biologic processes. Because of their small size, precise arrangement of the larvae is necessary to section them simultaneously. A technique was designed to embed groups of zebrafish larvae in a single plane in agarose before sectioning. Stained tissue sections of thousands of larvae can be examined efficiently using this embedding method. In addition to histologic analysis, PCR-based genotypic analysis of DNA from individual larval sections is also possible. This technique can be modified to accommodate any study that requires the histologic examination of many pieces of tissue.

Animals↗
PubMed1998

Alternation of one-lung and two-lung ventilations with the same single-lumen endobronchial tube during thoracoscopic surgery--a case report.

One-lung ventilation is sometimes necessary for procedures performed through thoracotomy. Single lumen endobronchial tube has been used purposefully for one lung ventilation since 1931. However, there are no reports on intra-operative alternation of one-lung and two-lung ventilations through the same single lumen endobronchial tube as it can only provide unilateral lung ventilation. We present a case in whom a tube exchanger was used to readjust tube position so as to provide alternation of one-lung and two-lung ventilations in a thoracoscopic procedure.

Anesthesia, General↗
PubMed1997

TCRV and TCRJ gene usage in MBP responding T cells from (B10.PL x PL/J)F1 mice is biased towards that of B10.PL mice.

We analyzed myelin basic protein (MBP) specific T cell hybridoma clones from (B10.PL x PL/J)F1 mice. MBP-reacting T cell hybridomas from F1 mice preferentially expressed B10.PL TcraV2.3 (53%) and B10.PL TcraV4.2 (13%) with minor expression of TcraV4.4 (13%) gene segments. A dominant expression of TcrbV8.2 (73%) accompanying with TcrbV8.1 (20%) and TcrbV13 (7%) gene segments have been identified in these MBP-reacting T cell hybridomas from F1 mice. There was less restrictive but non-random usage of the TcraJ and TcrbJ gene segments. Overall, the MBP-reacting T cell hybridomas from (B10.PL x PL/J)F1 mice were dominated by the MBP-reacting T cell pattern seen in B10.PL mice.

Amino Acid Sequence↗