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Biomedical subjects

Y H Yang

Publications and source records attributed to Y H Yang.

At least 73 records · Page 4Linked to original sources
PubMed2000

Heterologous expression of CYP2K1 and identification of the expressed protein (BV-CYP2K1) as lauric acid (omega-1)-hydroxylase and aflatoxin B1 exo-epoxidase.

LMC2 is the most abundant constitutively expressed hepatic cytochrome P450 found in sexually immature rainbow trout (Onchorynchus mykiss) and is also the isozyme that activates the carcinogen aflatoxin B1 (AFB1). This P450 has been cloned, sequenced, and designated as CYP2K1. The present report describes the heterologous expression of enzymatically active CYP2K1 (BV-CYP2K1) in baculovirus Spodoptera frugiperda (Sf9) insect cells and its catalytic and immunoreactivity characterization in comparison with that of the previously purified LMC2 P450. Homogenates of Sf9 cells expressing the CYP2K1 enzyme and LMC2 both catalyzed the hydroxylation of lauric acid and the epoxidation of AFB1 in the presence of rat NADPH-cytochrome P450 reductase. Both LMC2 and BV-CYP2K1 catalyzed the oxidation of lauric acid primarily at the (omega-1) position plus small amounts at the (omega-2) position. Formation of AFB1 epoxide was shown indirectly by the appearance of an AFB1 epoxide-glutathione conjugate when P450 incubation mixtures contained AFB1, glutathione (GSH) together with mouse liver cytosol or purified rat GSH-transferase. When the AFB1 epoxide-GSH conjugate produced by BV-CYP2K1 and purified LMC2 was analyzed by HPLC using a chiral column, it had a retention time identical to that produced by CYP3A4, a human P450 known to form exclusively the AFB1 exo-epoxide. These results, therefore, confirm that the cDNA-expressed CYP2K1 protein is catalytically and immunologically identical to purified trout LMC2 and that these two enzymes produce primarily the highly carcinogenic stereoisomeric exo-epoxide form of AFB1.

Aflatoxin B1↗
PubMed2000

Prenylflavonoids from hops inhibit the metabolic activation of the carcinogenic heterocyclic amine 2-amino-3-methylimidazo[4, 5-f]quinoline, mediated by cDNA-expressed human CYP1A2.

The heterocyclic amine 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) is a potential human carcinogen found in cooked food that requires initial metabolic activation by cytochrome P450s, primarily CYP1A2. The present study was conducted to examine whether recombinant human CYP1A2 expressed in insect cells mediates the metabolic activation of IQ and whether prenylflavonoids found in hops and beer would modulate the CYP1A2-mediated activation of IQ. The cDNA-expressed human CYP1A2 was found to strongly activate IQ as measured by the Ames Salmonella assay and by the covalent binding of IQ metabolites to calf thymus DNA and protein. Inhibition studies showed that the prenylchalcone xanthohumol and the prenylflavanones 8-prenylnaringenin and isoxanthohumol strongly inhibited the mutagenic activation of IQ mediated by cDNA-expressed human CYP1A2 in the Ames Salmonella assay. The three prenylflavonoids also markedly inhibited the human CYP1A2-mediated binding of IQ to metabolites that bind to DNA. The inhibition of the metabolic activation of IQ was paralleled by the inhibition of acetanilide 4-hydroxylase activity of human CYP1A2. Thus, xanthohumol, isoxanthohumol, and prenylflavanones 8-prenylnaringenin are potent inhibitors of the metabolic activation of IQ and may have the potential to act as chemopreventive agents against cancer induced by heterocyclic amines activated by CYP1A2.

Animals↗
PubMed2000

Costimulatory molecules expression and cytokine profiles of cord blood mononuclear cells in newborns with low and high risk of developing atopic diseases.

This study sought to determine predictors of atopic diseases in newborns. We evaluated the levels of expression of costimulatory molecules (CD80 and CD86) and the production of cytokines [interleukin (IL)-12, interferon (IFN)-gamma, IL-4, IL-10] in the cord blood of mononuclear cells in high risk newborns (n = 17), and compared them with those in low risk newborns (n = 25). Fluorescence-activated cell sorter (FACScan) analysis was performed to determine the expressions of CD80 and CD86 on activated B cells and monocytes of both groups. The levels of IL-10, IL-12p40 and IL-12p70 in the supernatant were assayed by enzyme-linked immunosorbent assay (ELISA), and also the mRNA levels by reverse transcription-polymerase chain reaction (RT-PCR). Intracellular staining of IL-4 and IFN-gamma in stimulated mononuclear cells was also performed as well. The expressions of CD80 and CD86 on B cells showed no significant difference between the high and low risk group. There was greater expression of CD86 on the monocytes of low risk newborns as compared to high risk newborns (p < 0.05). When B cells and monocytes isolated from the cord blood of both groups were stimulated with mitogens, the production of IL-10, IL-12p40, and IL-12p70 in the supernatants was not significantly different. The expressions of mRNA of IL-10, IL-12p35, and IL-12p40, and the intracellular staining of IL-4 and IFN-gamma in stimulated mononuclear cells were not significantly different between the two groups. These findings suggested that cytokine profiles in the cord blood cannot predict the development of atopic diseases. Determination of whether preferential expression of costimulatory molecules is of predictive value or not will require further study.

Antigens, CD↗
PubMed2000

[Site-directed mutagenesis and effects on the enzymatic properties of subtilisin E].

Site-directed mutagenesis was used to investigate the effects of S221C/P225A, N118S/S221C/P225A, D60N/N118S/S221C/P225A and Q103R/N118S/S221C/P225A mutations on the properties of Subtilisin E. It was found that S221C/P225A mutant is 73,000-fold decreased in amidase activity than subtilisin E and 3-fold increased than subtiligase in the ratio of esterase/amidase; N118S/S221C/P225A mutant has 3.6-fold and 15-fold decreased in amidase and esterase activity respectively and as a result, it has a 4-fold lower in the ratio of amidase/esterase than S221C/P225A mutant; Although it has no effect on the esterase activity, D60N/N118S/S221C/P225A mutant enhanced its ratio of amidase/esterase by 15 fold, 3.3-fold and 10.3 fold compared to N118S/S221C/P225A mutant, S221C/P225A mutant and subtiligase respectively; Q103R/N118S/S221C/P225A mutant, however, has a 5-fold enhanced in the amidase activity and 55-fold and 1000-fold decrease in the esterase activity and the ratio of esterase/amidase compared to N118S/S221C/P225A.

Amidohydrolases↗
PubMed2000

Childhood Churg-Strauss syndrome: report of a case.

Churg-Strauss syndrome (CSS) (allergic granulomatosis and angitis) is an uncommon form of systemic vasculitis, which is rare in children. It is characterized by peripheral blood hypereosinophilia, systemic necrotizing vasculitis, and a preceding history of bronchial asthma. We described a boy with initial presentation of poorly controlled bronchial asthma, allergic rhinitis, recurrent sinusitis and several episodes of hemoptysis since the age of 9. He then developed purpuric skin lesions, generalized soreness, and symptoms of mononeuritis multiplex at age 11. On admission to our hospital at the age of 12, he developed marked pericardial effusion. After a series of studies including chest computed tomography (CT), skin biopsy, nerve conduction study, and serological tests for autoantibodies, CSS was diagnosed. Thereafter, he received regular corticosteroid therapy, and his symptoms were generally well-controlled with occasional acute exacerbation. The clinical characteristics, diagnosis and management of CSS in children are also reviewed.

Child↗
PubMed2000

Crown diameters of the deciduous teeth of Taiwanese.

The purposes of this study were (1) to characterize the crown diameters of the deciduous teeth of Taiwanese; (2) to compare the differences in the deciduous crown diameters between different populations. The results might provide odontometric information in making preformed stainless steel crowns of the Chinese population. Study casts of 90 children (51 boys and 39 girls) of aged 3 to 6 years were used in this study. The maximum mesiodistal crown diameter (the greatest distance between the contact points of the approximal surfaces) and the buccolingual crown diameter (the greatest distance at a right angle to the mesiodistal measurement) were obtained by using an electronic digital caliper. Significant differences between antimeres were found in the mesiodistal diameters of maxillary canine and maxillary molars (p < 0.001) as well as in the buccolingual diameters of mandibular molars (p < 0.05). Excellent correlations between the antimeres of the corresponding teeth were found (r = 0.70 to 0.96). Boys generally had larger crown diameters than girls with the exception of mesiodistal diameters of maxillary and mandibular canines, and mandibular lateral incisor, whereas the statistically significant gender difference was only found in the buccolingual diameter of mandibular second molar (p < 0.05). The higher the percentage of sexual dimorphism, the larger the gender differences. The percentage of sexual dimorphism ranged from 0.09 to 1.94 for mesiodistal diameters and 0.04 to 2.86 for buccolingual diameters. The mandibular second molar was the most dimorphic tooth. Variations in the crown diameters of the deciduous teeth existed among and within different populations. Deciduous mesiodistal crown diameters of Taiwanese were, in general, smaller than those of Australian aborigines, Taiwan Chinese aborigines, and Hong Kong Chinese, but larger than those of American whites. When considering the buccolingual crown diameters, our data were significantly smaller than those of Icelanders, western Indians, and whites.

Child↗
PubMed2000

[Determination of fibronectin mRNA expression in patients with diabetic ulcers by quantitative polymerase chain reaction technique].

OBJECTIVE: To determine the characteristics and regularity of fibronectin mRNA expression in diabetic ulcers, and to investigate the relationship between the changes of fibronectin mRNA expression and pathogenesis of diabetic ulcer. METHODS: Biopsies were removed from the margins of diabetic foot ulcers, included surrounding skin as experimental group, and the biopsies from normal skin of the same patients as control group. The mRNA expression of fibronectin was measured by quantitative RT-PCR technique. RESULTS: The mRNA expression of fibronectin could be detected in both normal skin and diabetic foot ulcers, but the level of expression in diabetic ulcers was lower than that of normal skin. CONCLUSION: The level of mRNA expression of fibronectin in diabetic ulcers is decreased, which suggest that the down-regulation of transcription may be one of the mechanisms of chronic impaired ulcers.

Aged↗
PubMed2000

[Studies on quality standards for Pollen Typhae(puhuang)].

OBJECTIVE: To work out quality standards for Pollen Typhae(Puhuang). METHOD: Isorhamnetin-3-O-neohesperidoside, typhaneoside, isorhamnetin and beta-sitosterol in Pollen Typhae marketed in ten cities of China were identified by TLC. The contents of isorhamnetin-3-O-neohesperidoside and typhaneoside were determined by HPLC. RESULT: The method is sensitive and specific for identifying isorhamnetin-3-O-neohesperidoside, typhaneoside, isorhamnetin and beta-sitosterol. The linear ranges of isorhamnetin-3-O-neohesperidoside and typhaneoside were 0.188-0.940 microgram with and average recovery of 97.77%; and 0.164-0.820 microgram with an average recovery of 98.42% respectively. CONCLUSION: The method can be used both qualitatively and quantitatively as standards for the quality control of Pollen Typhae.

Drugs, Chinese Herbal↗
PubMed2000

[Characteristics of bFGF and TGF-beta expression in dermal chronic ulcers and hypertrophic scars and their effects on tissue repair].

OBJECTIVE: To localize the distribution of basic fibroblast growth factor (bFGF) and transforming growth factor-beta(TGF-beta) in tissues from dermal chronic ulcer and hypertrophic scar and to explore their effects on tissue repair. METHODS: Twenty-one cases were detected to localize the distribution of bFGF and TGF-beta, among them, there were 8 cases with dermal chronic ulcers, 8 cases with hypertrophic scars, and 5 cases of normal skin. RESULTS: Positive signal of bFGF and TGF-beta could be found in normal skin, mainly in the keratinocytes. In dermal chronic ulcers, positive signal of bFGF and TGF-beta could be found in granulation tissues. bFGF was localized mainly in fibroblasts cells and endothelial cells and TGF-beta mainly in inflammatory cells. In hypertrophic scar, the localization and signal density of bFGF was similar with those in granulation tissues, but the staining of TGF-beta was negative. CONCLUSION: The different distribution of bFGF and TGF-beta in dermal chronic ulcer and hypertrophic scar may be the reason of different results of tissue repair. The pathogenesis of wound healing delay in a condition of high concentration of growth factors may come from the binding disorder of growth factors and their receptors. bFGF may be involved in all process of formation of hypertrophic scar, but TGF-beta may only play roles in the early stage.

Adult↗
PubMed1999

Antiproliferative and cytotoxic effects of prenylated flavonoids from hops (Humulus lupulus) in human cancer cell lines.

Six flavonoids [xanthohumol (XN), 2',4',6',4-tetrahydroxy-3'-prenylchalcone (TP); 2',4',6',4-tetrahydroxy-3'-geranylchalcone (TG); dehydrocycloxanthohumol (DX); dehydrocycloxanthohumol hydrate (DH); and isoxanthohumol (IX)] from hops (Humulus lupulus) were tested for their antiproliferative activity in human breast cancer (MCF-7), colon cancer (HT-29) and ovarian cancer (A-2780) cells in vitro. XN, DX and IX caused a dose-dependent (0.1 to 100 microM) decrease in growth of all cancer cells. After a 2-day treatment, the concentrations at which the growth of MCF-7 cells was inhibited by 50% (IC50) were 13.3, 15.7 and 15.3 microM for XN, DX and IX, respectively. After a 4-day treatment, the IC50 for XN, DX and IX were 3.47, 6.87 and 4.69 microM, respectively. HT-29 cells were more resistant than MCF-7 cells to these flavonoids. In A-2780 cells, XN was highly antiproliferative with IC50 values of 0.52 and 5.2 microM after 2 and 4 days of exposure, respectively. At 100 microM, all the hop flavonoids were cytotoxic in the three cell lines. Growth inhibition of XN- and IX-treated MCF-7 cells was confirmed by cell counting. XN and IX inhibited DNA synthesis in MCF-7 cells. As antiproliferative agents, XN (chalcone) and IX (flavanone isomer of XN) may have potential chemopreventive activity against breast and ovarian cancer in humans.

Animals↗
PubMed1999

Phylogenetic relationships of Cheju horses to other horse breeds as determined by mtDNA D-loop sequence polymorphism.

Historical records suggest that horses inhabiting the island of Cheju in Korea are descendants of Mongolian horses introduced in 1276. Other studies, however, suggest that horses may have been present on the island prior to the Mongolian introduction. To determine the origin of the Cheju horses we used a phylogenetic analysis of sequences of the mitochondrial DNA (mtDNA) D-loop region, including tRNA Pro and parts of tRNA thr and tRNA Phe sequences (1102-bp excluding the tandem repeat region). Maximum parsimony and neighbor-joining trees were constructed using sequences determined for seven Cheju, four Mongolian, one Przewalskii and two Chinese Yunnan horses, and published sequences for one Swedish and three Thoroughbred horses. Donkey mtDNA was used as an outgroup. We found that the mtDNA D-loop sequence varies considerably within Mongolian, Cheju and Thoroughbred horse breeds, and that Cheju horses clustered with Mongolian horses as well as with horses from other distantly related breeds. On the basis of these findings we propose that horses on Cheju Island are of mixed origin in their maternal lineage, and that horses may have existed and been traded on the island before the Mongolian introduction.

Animals↗
PubMed1999

The Korean collaborative study on 11,000 prenatal genetic amniocentesis.

Since amniocentesis made prenatal diagnosis feasible in 1967, the method has been remarkably instrumental in obstetrical practice. A recent study conducted between 1980 and 1997 collected 11,000 amniocentesis procedures done at 10 university hospitals and tertiary centers in Korea. The study indicated that the use of amniocentesis on patients has increased steadily since 1980; however, the number has increased sharply for patients in the mid 1990's. In the 1980's, amniocentesis had been used primarily for patients in advanced maternal age groups (at least 35 years or older). In 1995, amniocentesis had been implemented for the detection of abnormal serum markers (37.6%), and by 1997, amniocentesis was involved in such diagnosis even more frequently (44.8%). Of the total number of uses, 270 (2.5%) involved the detection of chromosomal anomaly. In autosomal disorders, 96 Down syndrome, 33 Edward syndrome, and 6 Patau syndrome were diagnosed. In sex chromosomal anomaly, 10 Turner syndrome, and 10 Klinefelter syndrome were diagnosed. Added to that, 83 translocations, and 15 mosaicisms were diagnosed. Of the 322 cases with abnormal ultrasonographic findings, 21 (6.5%) resulted in chromosomal anomaly. The use of genetic amniocentesis as a prenatal diagnostic test for Korean women has risen 10-fold between 1988 and 1998. As stated earlier, amniocentesis had earlier been used primarily for those in advanced maternal age groups. Today, maternal serum markers and highly sensitive ultrasonic technology can detect many fetal anomalies which eventually necessitate amniocentesis.

Adult↗
PubMed1999

Sex differences in pediatric systemic lupus erythematosus: a retrospective analysis of 135 cases.

A retrospective review of 135 patients with systemic lupus erythematosus (SLE) (24 boys and 111 girls) under age 18 at the National Taiwan University Hospital (NTUH) from 1989 to 1998 was done. The aim of this retrospective study was to compare the differences in the age at diagnosis, clinical, laboratory features and survival among both sexes. The female to male ratio was 4.6:1. The mean age at the time of diagnosis was 13.7 years (range, 8y5m-18y) for male patients and 13.7 years (range, 6y1m-18y) for female patients. There was no significant differences in the mean age of diagnosis between the sexes. It was found that there were no significant differences in the clinical and laboratory features between male and female patients except for the prevalence of oral ulcers, alopecia and anti-SSA antibodies which were more frequent in the female group. The cumulative 5- and 10-year survival rates were 80.2% and 65%, respectively; male patients appeared to have a better survival, yet it did not reach any statistical significance. Univariate analysis showed that gender is not a significant factor on prognosis in pediatric SLE. Although abnormal creatinine was associated with poor mortality, it was not statistically significant on multivariate analysis.

Adolescent↗
PubMed1999

[Transforming growth factor beta 1 and interleukin 6 mRNA expression in wound tissues of patients with diabetic ulcers].

OBJECTIVE: To study the relationship between the changes of mRNA expression in wound tissues of diabetic ulcers and tissue repair. METHODS: The mRNA expression of TGF-beta 1 and IL-6 in eight bioptic samples of diabetic ulcers were detected by RT-PCR and pathologic methods, and the surrounding normal skins from the same patients were measured as control group. RESULTS: The mRNA expression levels of TGF-beta 1 were markedly decreased in the diabetic ulcers compared with control group, while the mRNA expression levels of IL-6 were increased at the same reaction conditions. CONCLUSION: The different changes of mRNA expression level of TGF-beta 1 and IL-6 in wound tissue result in low production and decreased activity of TGF-beta 1 and IL-6, which lower the reparative ability of wound tissue.

Aged↗
PubMed1999

[Observation of soluble interleukin-2 receptor(sIL-2R) and tumor necrosis factor(TNF) in patients with malignant tumors of salivary gland]

OBJECTIVE:To To study the clinical significance of sIL-2R and TNF in patients with malignant tumors of salivary gland.METHODS:The serum levels of sIL-2R and TNF in 30 patients were measured using a sandwich enzyme-linked immunosorbent assay (ELISA) and radiation immune assay (RIA).RESULTS:The results showed that serum sIL-2R levels in patients were significantly higher than those of controls (P<0.01).Four weeks after operation,the sIL-2R levels could be seen again in recurrent or metastatic individuals.The levels of TNF were normal.CONCLUSION:The consecutive observation of serum sIL-2R levels is helpful to judge the prognosis and monitor the relapses and metastases of malignant tumors of salivary gland.

Journal Article↗
PubMed1998

Cloning, sequencing, and tissue expression of CYP3A27, a new member of the CYP3A subfamily from embryonic and adult rainbow trout livers.

Screening of lambdagt11 and lambdagt22A cDNA libraries of livers from adult females and embryos of rainbow trout (Oncorhynchus mykiss), respectively, using rabbit anti-rainbow trout cytochrome P450 LMC5 polyclonal antibodies showed that there were identical cDNAs of 1802-bp nucleotides with open reading frames coding for proteins containing 518 amino acids (59,206 Da, pI = 6.39). The cDNA was assigned CYP3A27 by the P450 Nomenclature Committee to represent the first CYP3A subfamily member reported for aquatic species. The deduced N-terminal sequence of CYP3A27 was in agreement with 8 of the first 12 confirmed amino acid residues from Edman degradation of LMC5, a P450 previously isolated from juvenile trout liver. In similarity comparisons between species by positional alignment, the deduced amino acid sequence of rainbow trout CYP3A27 was 56.4% identical with dog CYP3A12, 56.0% with monkey CYP3A8, 54.9% with human CYP3A4, 54.7% with rat CYP3A9, and 54.2% with sheep CYP3A24. Marked differences in sex, age, and tissue expression of CYP3A27 in rainbow trout were observed at the mRNA level as shown by Northern blots. The major extrahepatic expression site for CYP3A27 was upper small intestine. Females expressed considerably more CYP3A27 mRNA than male in the fish examined. Southern blot analysis of restriction enzyme-digested rainbow trout genomic DNA demonstrated that multiple CYP3A27-related genes exist in rainbow trout.

Amino Acid Sequence↗
PubMed1998

CYP2M1: cloning, sequencing, and expression of a new cytochrome P450 from rainbow trout liver with fatty acid (omega-6)-hydroxylation activity.

A cDNA clone was isolated from a female rainbow trout liver lambda g tau 11 library using polyclonal antibodies raised against rainbow trout cytochrome P450 LMC1. This 2149-nucleotide clone contained an open reading frame encoding a protein of 499 amino acids with a calculated M(r) of 56,850 Da. On the basis of cytochrome P450 (P450) amino acid sequence comparisons, this rainbow trout P450 was assigned by the P450 Nomenclature Committee to a new P450 subfamily designated as CYP2M1. Northern blot results suggest that the expression of CYP2M1 at the transcriptional level was generally sex, tissue, and age specific. By use of a full-length CYP2M1 cDNA probe, it was observed that this cDNA hybridized strongly to a single 2.2-kb transcript in juvenile female rainbow trout trunk kidney and in liver from juvenile and sexually mature trout from both sexes. Negligible amounts of mRNA hybridizable to CYP2M1 cDNA were found in the juvenile and sexually mature male trunk kidney. cDNA-directed expression in COS-7 cells and of recombinant baculovirus in insect cells produced a protein that was reactive with rabbit anti-trout P450 LMC1 polyclonal antibody and exhibited the unique (omega-6)-hydroxylation toward lauric acid previously observed with rainbow trout P450 LMC1.

Amino Acid Sequence↗