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Biomedical subjects

Y Bai

Publications and source records attributed to Y Bai.

At least 127 records · Page 7Linked to original sources
PubMed1997

Structure-function analysis of TAF130: identification and characterization of a high-affinity TATA-binding protein interaction domain in the N terminus of yeast TAF(II)130.

We report structure-function analyses of TAF130, the single-copy essential yeast gene encoding the 130,000-Mr yeast TATA-binding protein (TBP)-associated factor TAF(II)130 (yTAF(II)130). A systematic family of TAF130 mutants was generated, and these mutant TAF130 alleles were introduced into yeast in both single and multiple copies to test for their ability to complement a taf130delta null allele and support cell growth. All mutant proteins were stably expressed in vivo. The complementation tests indicated that a large portion (amino acids 208 to 303 as well as amino acids 367 to 1037) of yTAF(II)130 is required to support cell growth. Direct protein blotting and coimmunoprecipitation analyses showed that two N-terminal deletions which remove portions of yTAF(II)130 amino acids 2 to 115 dramatically decrease the ability of these mutant yTAF(II)130 proteins to bind TBP. Cells bearing either of these two TAF130 mutant alleles also exhibit a slow-growth phenotype. Consistent with these observations, overexpression of TBP can correct this growth deficiency as well as increase the amount of TBP interacting with yTAF(II)130 in vivo. Our results provide the first combined genetic and biochemical evidence that yTAF(II)130 binds to yeast TBP in vivo through yTAF(II)130 N-terminal sequences and that this binding is physiologically significant. By using fluorescence anisotropy spectroscopic binding measurements, the affinity of the interaction of TBP for the N-terminal TBP-binding domain of yTAF(II)130 was measured, and the Kd was found to be about 1 nM. Moreover, we found that the N-terminal domain of yTAF(II)130 actively dissociated TBP from TATA box-containing DNA.

Amino Acid Sequence↗
PubMed1997

[Further clinical analysis on the prognosis of chronic lymphocytic thyroiditis].

OBJECTIVE AND METHODS: There have been many reports on the incidence of hypothyroidism and thyroid carcinoma in chronic lymphocytic thyroiditis patients, however, the incidence of thyroid carcinoma had been a widely debated issue. Therefore 300 cases of chronic lymphocytic thyroiditis from 1964 to 1995 were reviewed. There were 37 males and 263 females, and 52 had a pathological diagnosis of chronic lymphocytic thyroiditis. RESULTS: Among 300 patients, 2 had coexistent thyroid papillary carcinoma. The original symptom in 64.3% patients was hypothyroidism, and the total incidence of hypothyroidism was 76%. It was also indicated in this study that the occurrence of hypothyroidism in chronic lymphocytic thyroiditis patient was associated with the elevated level of antithyroglobulin antibody, enlargement and tenderness of thyroid gland. CONCLUSION: In our study, as the low incidence of coexisted thyroid carcinoma, with the high incidence of hypothyroidism it seemed to be that the elevated antithyroglobulin antibody could be a more effective factor in the development of hypothyroidism in chronic lymphocytic thyroiditis.

Adolescent↗
PubMed1997

[A study on the changes of the estrogen level in the condylar cartilages in young growing rats after functional mandibular protrusion].

Fifty female SD rats of 4-week-old were selected, divided equally and randomly into experimental and control groups. Simulated functional appliances were used to guide the mandibles of the rats forwards. The animals were sacrificed after 3 days, 1 week, 2 weeks, 3 weeks and 4 weeks. The method of radioimmunoassay (RIA) was performed to quantitively detect the level of estrogen in the condylar cartilages. The results showed: 1. High levels of estrogen were detected in the condylar cartilages during their actively proliferative period. When they differentiated gradually, the levels of estrogen decreased. 2. The amount of estrogen was increased significantly after functional mandibular protrusion, especially during the period of the active proliferation of the condylar cartilages. It is suggested that estrogen has a close relationship with the hyperplasia and hypertrophy of the condylar chondrocytes and the increment of the levels of estrogen in the condylar cartilages will further promote the proliferation and functional adaptive remodelling of the condylar cartilages.

Animals↗
PubMed1997

[Protective effects of exogenous superoxide dismutase on rabbit retinal injury by acute intraocular hypertension].

OBJECTIVE: To study active oxygen and free radical injury in rabbit retina during elevated intraocular pressure and the protective effect of exogenous superoxide dismutase (SOD) on the retinal damage by the hypertension. METHODS: Lipid peroxidative product, malondialdehyde (MDA), activity of SOD and glutathione peroxidase (GSH-Px), reduced GSH in the retinal tissue were measured during 24 h after the release of an ocular hypertension, 6.67 kPa (1 kPa = 7.5 mmHg) maintaining for 1.5 h, and the effects of retrobulbarly injected Cu-Zn-SOD on the level of MDA and the activity of SOD in the retinal tissue after the release of ocular hypertension for 12 h were observed. RESULTS: MDA increased gradually during 0-12 h after the release of ocular hypertension and maintained at a relatively high level in 12-24 h. The activity of SOD and GSH-Px was lower than normal level immediately after the release, and then increased to a certain different extent. But the activity of SOD began to decrease gradually 4 h after the release. GSH had no significant changes during 24 h after the release. Retrobulbar injection of Cu-Zn-SOD reduced the production of MDA in the retinal tissue and enhanced SOD activity. CONCLUSIONS: Active oxygen and free radicals participate the rabbit retinal injury by elevated intraocular pressure. A high dose of Cu-Zn-SOD retrobulbar injection plays a beneficial role in enhancing the antioxidative ability of the retina.

Animals↗
PubMed1997

[Facial proportions of the young with the beautiful faces of Sichuan descent].

In this study, eighteen indexes of facial proportions were established in 72 youngsters with beautiful faces of Sichuan descent, who haven't been done operation on and orthodontics in our country. The results indicated that there were not most sexual difference of the facial proportions between male and female in most indexes, and also were not national difference of facial proportions between Chinese and Japanese. It also showed some progresses in clinical practice.

Adolescent↗
PubMed1997

[Effect of body position changes and circadian rhythm on cerebral blood flow velocity].

To study the effects of -6 degrees head down tilt (HDT), upright posture and 24 h circadian rhythm on cerebral blood flow (CBF) velocity in humans, the CBF velocity was measured by use of transcranial Doppler technique in the middle cerebral artery (MCA) of 12 healthy male subjects. The results showed that the mean CBF velocity increased significantly during -6 degrees HDT and decreased during upright posture, and CBF velocity was higher in day time than at night.

Blood Flow Velocity↗
PubMed1997

[The establishment of antigen sandwiched ELISA for detection of total antibodies to hepatitis C virus].

An antigen sandwiched ELISA for detection of the total antibodies to HCV was established using genetically engineered proteins and synthesized peptides located in the structural and nonstructural regions of HCV genomes as coated antigens and were labeled by horseradish peroxidase, respectively. A comparison of antigen sandwiched ELISA with indirect ELISA showed that the sensitivity of sandwiched system (1:128) was little higher than that of indirect ELISA (1:64), the specificities of both systems were all 100%. This reagent may detect all classes of antibody to HCV in serum, mainly IgG and IgM and is a new diagnostic reagent for detection and early diagnosis of HCV infection.

Enzyme-Linked Immunosorbent Assay↗
PubMed1997

[Primary analysis of the situation of hepatitis G virus infection in different groups of people].

In order to investigate the situation of hepatitis G virus (HGV) infection among different groups of people, two self-selected peptides from HGV NS5 were used to develop an indirect ELISA for anti-HGV IgG detection. 1209 sera from different peoples were detected and the positive rate of anti-HGV IgG was (3.8%). Among these groups the group of non A-E hepatitis had the highest anti-HGV positive rate (20.5%), higher than that in the groups of natural people (0.8%) and other hepatitis patients (3.3%), the difference was significant. The anti-HGV IgG positive rate in the group of HC patients 8.0% was higher than that in other hepatitis A-E patients, the positive rate (8.0%) in paid donors was higher than that in voluntary donors (0%), and that in groups with venereal diseases and HIV infection were 3.6% and 8.0%, respectively. The results suggested that there has higher rate of HGV infection in our country; HGV is the important factor causing non A-E, the paid donors is the dangerous group, they should be strictly screened, and the people with transfusion have higher rate of HGV infection. Since there is different rate of HGV infection in different human population so it is important to study further the epidemiological characteristics of HGV for its prevention.

China↗
PubMed1997

[The relationship between autoimmune thyroiditis and TNF alpha: a preliminary study].

OBJECTIVE: To observe the action of tumor necrosis factor-alpha (TNF alpha) in the pathogenesis of autoimmune thyroiditis. METHODS: The activity of TNF alpha of peripheral blood mononuclear cells was detected in 25 cases of autoimmune thyroiditis, 9 cases of Grave's disease, and 18 normal controls by ELISA and bioassay. RESULTS: The activity of TNF alpha in patients with autoimmune thyrioditis was significantly higher than that in normal controls (P < 0.001), and in patients with Grave's diseases significantly lower than that in normal controls (P < 0.01). TNF alpha activity detected by two methods showed a good correlation (r = 0.972 P < 0.001). There were a negative correlation between TNF alpha and TT3 or FT3 (r = -0.437, -0.432 respectively, both P < 0.05) and a positive correlation between TNF alpha and TPO-Ab or TGA (r = 0.53, 0.51 respectively, both P < 0.01). TNF alpha activity was not associated with the period of disease and the size of thyriod. CONCLUSION: TNF alpha exerts an important role in the pathogenesis of autoimmune thyroiditis.

Adult↗
PubMed1997

[Changes of CGRP levels in plasma and CGRP mRNA in dorsal root ganglia during endotoxicosis in the rat].

To investigate the changes of both CGRP release and synthesis during endotoxicosis, CGRP mRNA in thoracolumbar dorsal root ganglia (DRG) was determined by the semi-quantity RT-PCR and the CGRP levels in plasma were measured by RIA. The results showed that plasma CGRP, but not mRNA, began to increase 30 min after endotoxin (5 mg/kg, i.v.) administration. On the other hand, the CGRP levels in plasma and CGRP mRNA in DRG were significantly increased by 142% and 32% respectively at the 3 h of injection and by 216% and 85% respectively at the 8 h of injection. The data suggest that not only the release of CGRP from the peripheral organs, but also the transcription of CGRP mRNA and synthesis of CGRP in sensory neurons are increased during the development of endotoxicosis in the rat. Presumably the DRG is an important source of CGRP release in the response to endotoxicosis.

Animals↗
PubMed1997

[Purification and some properties of superoxide dismutase from Fusarium moniliform].

Superoxide dismutase from Fusarium moniliform was purified by the steps including heating, ammonium sulfate fractionation, Sephedax G-100 gel filtration and DEAE-Sephadex A-50 chromatography. The results showed that the enzyme was a Mn-SOD with the specific activity of 2640 U/mg and had two homogenous subunits whose molecular mass were 14.5 kD. The wave length of max. absorbing peak in ultraviolet spectrum was 276 nm which was not similar with other resource of SOD. The composition of amino acid was also analyzed.

Amino Acids↗
PubMed1996

TBP-associated factors are not generally required for transcriptional activation in yeast.

The transcription factor TFIID, a central component of the eukaryotic RNA polymerase II (Pol II) transcription apparatus, comprises the TATA-binding protein (TBP) and approximately ten TBP-associated factors (TAFs). Although the essential role of TBP in all eukaryotic transcription has been extensively analysed in vivo and in vitro, the function of the TAFs is less clear. In vitro, TAFs are dispensable for basal transcription but are required for the response to activators. In addition, specific TAFs may act as molecular bridges between particular activators and the general transcription machinery. In vivo, TAFS are required for yeast and mammalian cell growth, but little is known about their specific transcriptional functions. Using conditional alleles created by a new double-shutoff method, we show here that TAF depletion in yeast cells can reduce transcription from some promoters lacking conventional TATA elements. However, TAF depletion has surprisingly little effect on transcriptional enhancement by several activators, indicating that TAFs are not generally required for transcriptional activation in yeast.

Alleles↗
PubMed1996

A Rad52 homolog is required for RAD51-independent mitotic recombination in Saccharomyces cerevisiae.

With the use of an intrachromosomal inverted-repeat as a recombination reporter we have previously shown that mitotic recombination is dependent on the RAD52 gene. However, recombination was found to be reduced only 4-fold by mutation of RAD51, which encodes a homolog of bacterial RecA proteins. A rad51, which strain containing the recombination reporter was mutagenized to identify components of the RAD51-independent pathway. One mutation identified, rad59, reduced recombination 1200-fold in the presence of a rad51 mutation, but only 4- to 5-fold in a wild-type background. Thus the rad51 and rad59 mutations reduce recombination synergistically. The rad59 mutation reduced both spontaneous and double-strand-break-induced recombination between inverted repeats. However, the rate of interchromosomal recombination was increased in a rad59 homozygous diploid. These observations suggest that RAD59 functions specifically in intrachromosomal recombination. The rad59 mutant strain was sensitive to ionizing radiation, and this phenotype was used to clone the RAD59 gene by complementation. The gene encodes a protein of 238 amino acids with significant homology to members of the Rad52 family. Overexpression of RAD52 was found to suppress the DNA repair and recombination defects conferred by the rad59 mutation, suggesting that these proteins have overlapping roles or function as a complex.

Amino Acid Sequence↗
PubMed1996

Obese gene expression alters the ability of 30A5 preadipocytes to respond to lipogenic hormones.

Leptin, the product of the ob gene, controls food-intake and weight loss in the ob mouse. Although the target(s) of the circulating leptin is presumed to be the brain which then orchestrates food-intake and weight loss, how leptin functions in the process of weight loss is unknown. In this report, we present evidence that ob gene expression in cultured cells suppresses acetyl-CoA carboxylase gene expression and lipid synthesis which are induced by hormone treatment. This is the first example in which leptin has been found to suppress defined biochemical reactions that contribute to lipid accumulation without the participation of the brain.

Acetyl-CoA Carboxylase↗
PubMed1996

Future directions in folding: the multi-state nature of protein structure.

All possible protein folding intermediates exist in equilibrium with the native protein at native as well as non-native conditions, with occupation determined by their free energy level. The study of these forms can illuminate the fundamental principles of protein structure and folding. Hydrogen exchange methods can be used to detect and characterize these partially unfolded forms at native conditions and as a function of mild denaturant and temperature. This information illuminates the requirements that govern the ability of kinetic and equilibrium methods to study folding intermediates.

Computer Simulation↗
PubMed1996

Interleukin-1 beta increases leukemia inhibitory factor mRNA levels through transient stimulation of transcription rate.

Interleukin-1 beta (IL-1 beta) induces leukemia inhibitor factor (LIF) expression in a number of cell types including non-neuronal cells of the sympathetic superior cervical ganglion (SCG). Upregulation of LIF by inflammatory cytokines is usually associated with injury response. We characterized the molecular mechanism of LIF mRNA regulation by IL-1 beta in explanted neonatal rat SCG and a Schwann cell line. IL-1 beta increases LIF mRNA levels by interacting with IL-1 receptors in SCG, since this induction could be diminished by inclusion of either soluble IL-1 receptors or IL-1 receptor antagonist. The antiinflammatory glucocorticoid dexamethasone also inhibits LIF mRNA induction by IL-1 beta. LIF mRNA encodes a 3' AU-rich mRNA stability control sequence, but IL-1 beta does not appear to regulate the decay of LIF mRNA by this mechanism. IL-1 beta does not raise LIF gene transcription rate in cultured SCG 6 or 24 h after addition of IL-1 beta as measured by nuclear run-on assays. LIF gene transcription is induced repidly and transiently in an immortalized Schwann cell line, returning to uninduced rates by 1 h after induction. These results suggest that the IL-1 beta induction of LIF gene expression is at least partially transcriptional, but that LIF mRNA increases to a greater extent than LIF transcription, suggesting the possibility of posttranscriptional regulation as well.

Animals↗
PubMed1996

Study of the antioxidant enzymes in human brain tumors.

The activities of antioxidant enzymes i.e. Cu, Zn-SOD, Mn-SOD, CAT, and GSH-Px in the normal brain and brain tumors, as well as the two varieties of SOD in the mitochondria were examined and correlated to the histopathological diagnosis and the degree of malignancy of tumors. It was found that these scavenging enzymes of oxygen free radicals were expressed with great regularity in brain tumors. Both Cu, Zn-SOD and Mn-SOD were decreased in descending order in meningiomas, low grade astrocytomas, high grade astrocytomas and medulloblastomas. Furthermore, the reduction of Mn-SOD in mitochondria was proportionate to that of the whole tissues. While in contrast to the SODs, the CAT levels were significantly increased in ascending order in high grade astrocytomas, low grade astrocytomas and meningiomas. GSH-Px increased in meningiomas but not in gliomas.

Antioxidants↗