PubMed Health⌕ Search

Biomedical subjects

W M Yang

Publications and source records attributed to W M Yang.

27 records · Page 2Linked to original sources
PubMed1996

XAP2, a novel hepatitis B virus X-associated protein that inhibits X transactivation.

The hepatitis B virus X protein is a promiscuous transcriptional transactivator. Transactivation by the X protein is most likely mediated through binding to different cellular factors. Using the yeast two-hybrid method, we have isolated a clone that encodes a novel X-associated cellular protein: XAP2. X and XAP2 interactions also occur in vitro. Antiserum raised against XAP2 recognizes a cytoplasmic protein with an apparent molecular mass of 36 kDa. The interaction between X and XAP2 requires a small region on X containing amino acids 13-26. From Northern blot analyses, XAP2 is ubiquitously expressed in both liver-derived and non-liver-derived cell lines as well as in normal non-liver tissues. In contrast, XAP2 is expressed in very low level in the normal human liver. In transfection assays, overexpression of XAP2 abolishes transactivation by the X protein. Based on these results, we suggest that XAP2 is an important cellular negative regulator of the X protein, and that X-XAP2 interaction may play a role in HBV pathology.

Amino Acid Sequence↗
PubMed1996

Transcriptional repression by YY1 is mediated by interaction with a mammalian homolog of the yeast global regulator RPD3.

YY1 is a mammalian zinc-finger transcription factor with unusual structural and functional features. It has been implicated as a positive and a negative regulatory factor that binds to the CCATNTT consensus DNA element located in promoters of many cellular and viral genes. A mammalian cDNA that encodes a YY1-binding protein and possesses sequence homology with the yeast transcriptional factor RPD3 has been identified. A Gal4 DNA binding domain-mammalian RPD3 fusion protein strongly represses transcription from a promoter containing Gal4 binding sites. Association between YY1 and mammalian RPD3 requires a glycine-rich region on YY1. Mutations in this region abolish the interaction with mammalian RPD3 and eliminate transcriptional repression by YY1. These data suggest that YY1 negatively regulates transcription by tethering RPD3 to DNA as a cofactor and that this transcriptional mechanism is highly conserved from yeast to human.

Amino Acid Sequence↗
PubMed1995

Cyclophilin A and FKBP12 interact with YY1 and alter its transcriptional activity.

YY1 is a zinc finger transcription factor with unusual structural and functional features. In a yeast two-hybrid screen, two cellular proteins, cyclophilin A (CyPA) and FK506-binding protein 12 (FKBP12), interacted with YY1. These interactions are specific and also occur in mammalian cells. Cyclosporin A and FK506 efficiently disrupt the YY1-CyPA and YY1-FKBP12 interactions. Overexpression of human CyPA and FKBP12 have different effects on YY1-regulated transcription with these effects being promoter-dependent. These results suggest that immunophilins may be mediators in the functional role of YY1.

Amino Acid Isomerases↗
PubMed1995

Experience with repair of hypospadias using bladder mucosa in adolescents and adults.

From July 1984 to January 1994, 113 hypospadias operations were performed using a free bladder mucosa graft. There were 31 primary cases and 82 secondary cases in which prior operations had been done. The meatus was penile in 33 patients, penoscrotal in 72 and perineal in 8. The cosmetic and functional results were satisfactory. Postoperative complications included 8 fistulas that required closure and 6 cases of stenosis treated by dilation. Our results suggest that hypospadias repair with a bladder mucosa graft is feasible and reliable. The technique has been performed successfully in the most complex as well as simple cases in adults and adolescents.

Adolescent↗
PubMed1994

[Deposition of air particles with polycyclic aromatic hydrocarbons (PAH) in human respiratory tract].

Atmospheric concentrations of five sizes of particles with PAH were determined in Taiyuan, and deposition of PAH in human respiratory tract was estimated. Results showed 47%-70% of air PAH concentrated in the particles less than 2 microns in diameter. Total PAH deposition in respiratory tract measured 12. 53 micrograms per day, and 53% of them deposited in nasopharyngeal region, 65% in tracheobronchial region and 32% in alveoli.

Air Pollutants↗
PubMed1991

Role of heat shock transcription factor in yeast metallothionein gene expression.

The induction of Saccharomyces cerevisiae metallothionein gene transcription by Cu and Ag is mediated by the ACE1 transcription factor. In an effort to detect additional stimuli and factors that regulate metallothionein gene transcription, we isolated a Cu-resistant suppressor mutant of an ACE1 deletion strain. Even in the absence of metals, the suppressor mutant exhibited high basal levels of metallothionein gene transcription that required upstream promoter sequences. The suppressor gene was cloned, and its predicted product was shown to correspond to yeast heat shock transcription factor with a single-amino-acid substitution in the DNA-binding domain. The mutant heat shock factor bound strongly to metallothionein gene upstream promoter sequences, whereas wild-type heat shock factor interacted weakly with the same region. Heat treatment led to a slight but reproducible induction of metallothionein gene expression in both wild-type and suppressor strains, and Cd induced transcription in the mutant strain. These studies provide evidence for multiple pathways of metallothionein gene transcriptional regulation in S. cerevisiae.

Chromosome Deletion↗
PubMed1983

Gas-to-liquid permeation in silicon-containing, crosslinked, glassy copolymers of methyl methacrylate.

Copolymers of methyl methacrylate with disiloxane derivatives have been proposed as biomaterials for contact lens applications. Although glassy, these copolymers exhibit high oxygen permeability and adequate wettability so that they can be used for manufacture of hard, extended wear lenses. Crosslinked copolymers of poly(methylmethacrylate-co-1,3-bis(methacryloxymethyl) -1,1,3,3-tetramethyl-disiloxane), P(MMA-co-BMTDS), containing from 0.085 to 0.53 mole fraction of BMTDS were prepared and tested for oxygen permeation using a novel apparatus which simulates the atmosphere/lens/cornea conditions. The gas-to-liquid dissolved oxygen permeability, P gd1 was determined and it was found to increase with BMTDS content. Permeability values for P(MMA-co-BMTDS) at 34 degrees C were significantly higher than for pure homopolymer PMMA, although these copolymers were glassy at this temperature. The increased oxygen permeation was attributed to increased oxygen solubility in the copolymers due to the presence of the -Si-O-bonds.

Biocompatible Materials↗
PubMedDate not supplied

Preoperative intermittent manual traction in congenital dislocation of the hip.

To avoid prolonged hospitalization and the complications of skin and skeletal traction, we have devised a method of intermittent preoperative manual traction in the treatment of congenital dislocation of the hip. Of 60 hips that were followed for more than 1 year, 88.3% had Class I or Class II results according to Severin's criteria. No hip in this series was complicated by avascular necrosis of the proximal femoral epiphysis.

Child↗