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Biomedical subjects

Y Bai

Publications and source records attributed to Y Bai.

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

Tight control of respiration by NADH dehydrogenase ND5 subunit gene expression in mouse mitochondria.

A mouse cell variant carrying in heteroplasmic form a nonsense mutation in the mitochondrial DNA-encoded ND5 subunit of the respiratory NADH dehydrogenase has been isolated and characterized. The derivation from this mutant of a large number of cell lines containing between 4 and 100% of the normal number of wild-type ND5 genes has allowed an analysis of the genetic and functional thresholds operating in mouse mitochondria. In wild-type cells, approximately 40% of the ND5 mRNA level was in excess of that required for ND5 subunit synthesis. However, in heteroplasmic cells, the functional mRNA level decreased in proportion to the number of wild-type ND5 genes over a 25-fold range, pointing to the lack of any compensatory increase in rate of transcription and/or stability of mRNA. Most strikingly, the highest ND5 synthesis rate was just sufficient to support the maximum NADH dehydrogenase-dependent respiration rate, with no upregulation of translation occurring with decreasing wild-type mRNA levels. These results indicate that, despite the large excess of genetic potential of the mammalian mitochondrial genome, respiration is tightly regulated by ND5 gene expression.

Amino Acid Sequence↗
PubMed2000

Antibodies to HIV-1 gp41 recognize synthetic peptides of human IFN-alpha and IFN-beta.

Based on our finding that a common epitope exists between HIV-1 gp41 and human type I interferons (IFN-alpha and IFN-beta), and increased levels of antibodies against human IFN-alpha and IFN-beta were observed in HIV-1-infected individuals, we tried to explain the mechanism of increased levels of antibodies. Mouse antisera recognizing HIV-1 recombinant soluble (rs) gp41 (aa 539-684) interacted with two synthetic peptides sequence-corresponding to the IFN-alpha/beta receptor binding site on human IFN-alpha and IFN-beta, while normal mouse serum (pooled normal sera) did not. The anti-rspg41 antisera after adsorption by IFN-beta sepharose column lost the activity of interaction with both synthetic peptides. In another experiment, rsgp41 could bind to sepharose column conjugated with anti-IFN-beta polyclonal antibodies (IgG). These results indicate that the common epitope on gp41 and type I interferons could induce antibodies recognizing the receptor binding site on IFN-alpha and IFN-beta, suggesting that increased levels of antibodies against IFN-alpha and IFN-beta in HIV-1-infected individuals could be induced by gp41.

Animals↗
PubMed2000

[Low expression of nm23-H1 mRNA and its protein in breast cancer].

OBJECTIVE: To explore the expression of nm23-H1 mRNA and its protein in breast cancer and its correlation to the biologic behavior. METHODS: RT-PCR and immunohistochemical method were employed to detect the expression of nm23-H1 mRNA and its protein in 58 breast cancer tissues. RESULTS: Low level expression of nm23-H1 mRNA and protein was shown in 44.8% and 48.2% of examined cases respectively. The low expression of nm23-H1 mRNA was correlated, but not always parallel to the protein expression. The low level expression of nm23-H1 mRNA or the protein was significantly associated with lymphatic metastasis of the cancer. CONCLUSION: Examination of nm23-H1 expression may be of significance in evaluating metastatic potentiality and prognosis of breast cancer.

Breast Neoplasms↗
PubMed2000

[Systematic analysis of agro-ecoclimatic resources in Gansu Province].

Based on the over years data from 86 meterological stations in Gansu Province, the agro-ecoclimatic resources in this province was systematically analyzed. Resource indices Cr, efficiency indices Ce and utilization coefficient K were calculated by using the dynamic models of agro-ecoclimatic suitability degree. According to the average monthly efficiency indices Ce, the agro-ecoclimatic resources were divided into 7 types and 3 subtypes by fuzzy cluster. The potentiality matching condition and utility degree of agro-ecoclimatic resources showed the evident characteristic of spatial differentiation. Generally, the south was superior to the north, and the east was superior to the west in terms of these parameters, with the type of South Gansu Mountain much better than that of Hexi Corridor. Some suggestions about the exploitation and utilization of the agro-ecoclimatic resources in Gansu province were proposed.

Agriculture↗
PubMed2000

[Beta-diversity of Stipa communities in Inner Mongolia Plateau].

The beta-diversity characteristics of four Stipa communities (S. baicalensis, S. grandis, S. krylovii and S. klemenzii) were studied using comparable plots methods. As a measurement of species turnover within communities, Whittacker's index(beta ws) was size-dependent, and reduced gradually with the increasing quadrat size. Under the same scale, beta ws indices of the communities were similar. Cody's index (beta c) was also affected by sampling size. beta c increased initially as quadrat size enlarged, then stabilized over the size of 0.5 m2 for S. baicalensis and S. grandis communities, and 2 m2 for S. krylovii and S. klemenzii communities. S. baicalensis community had the highest Cody index, while S. klemenzii community had the lowest one. In most cases, the within-community distance interval had a relatively high effect on Cody index; From S. baicalensis to S. klemenzii community, the functional group diversities of forbs, perennial bunch and rhizome grasses decreased greatly, the diversity of intermediate xerads reduced significantly, and the diversity of xerads increased firstly, and then declined for S. klemenzii community. The changes in species composition of four Stipa communities could give a reflection to the degrees of community replacement along ecological gradients, and Cody indices between the communities reduced gradually. The Morisita-Horn similarity coefficient between S. baicalensis and S. grandis community was significantly higher (0.72) than those between S. grandis and S. krylovii communities (0.55), and between S. krylovii and S. klemenzii communities(0.42).

China↗
PubMed2000

[Repair of spontaneous rupture of esophagus by pedicled greater omentum (10 cases report)].

OBJECTIVE: To evaluate the effect of various covering tissues for improving the cure rate of spontaneous rupture of esophagus. METHODS: From 1970 to 1994, 13 cases with spontaneous rupture of esophagus were performed primary repair, among them, 10 cases were covered by pedicled greater omentum after impair, and the other 3 cases were covered by pedicled pleural flap. RESULTS: Satisfactory result and complete recovery were obtained in all 10 cases by using pedicled greater omentum. Two cases among 3 cases using pedicled pleural flap suffered re-rupture of esophagus at 5 days and 8 days after operation, and died because of whole body exhaustion. CONCLUSION: Pedicled greater omentum is a good covering tissue for repair of spontaneous rupture of esophagus.

Adult↗
PubMed2000

[Clinical significance of sentinel lymph node biopsy in breast cancer].

OBJECTIVE: To study the necessity, feasibility, accuracy and clinical value of sentinel lymph node(SLN) biopsy in the management of breast cancer. METHODS: Technetium-99m labeled colloid particles were injected subcutaneously below the breast tumor before mastectomy. The sentinel lymph nodes identified by lymphoscintigraphy and gamma-counter were dissected out from the excised axillary tissue and separately examined manually for consistency and histologically. RESULTS: In 30 cases studied, SLNs were identified in all but one, with a detection rate of 96.7%. Metastases were detected in SLNS in 8 cases. The other case showed positive axillary lymph nodes but SLN was negative. The sensitivity of SLN biopsy in this study was 88.9%, accuracy was 93.3%, false positive was 0, false negative was 11.1%. CONCLUSION: SLN biopsy, though still under investigation, may in the future substitute routine axillary lymph node dissection in the management of breast cancer.

Adult↗
PubMed2000

[Clinical analysis of 5 cases of relapsing polychondritis].

OBJECTIVE: To describe the clinical manifestation of relapsing polychondritis(RP) and evaluate the medical therapy of RP, especially management of airway stenosis with intervening method. METHOD: Retrospective analysis of 5 cases of RP treated in our hospital since 1995 with reviewing of large series of cases in reported literatures. RESULT: RP is a rare multisystem disorder characterized by recurrent inflammation and progressive degeneration of cartilaginous structure and connective tissue. Medical treatment with corticosteroids, immunosuppressive drugs and dapsone could not interrupt the progression of the disease. Involvement of the respiratory tract is life-threatening and intervening therapy such as tracheostomy, endotracheal intubation or tracheobronchial stents is needed, one case of relieving severe dyspnea caused by extensive tracheobronchial collapse in RP with self-expanding metallic stents was presented. CONCLUSION: It is important to make the diagnosis of RP according to the clinical features and carry out medial treatment at early stage, positive airway pressure support and intervening methods to prevent the airway collapse should be considered when the laryngotracheobronchial involvement aggreviates.

Adrenal Cortex Hormones↗
PubMed2000

[Detection of remnants after removal of medullary thyroid carcinoma].

OBJECTIVE: To assess whether calcium stimulation test or somatostain-receptor (SS-R) imaging could early detect remnants after removal of medullary thyroid carcinoma (MTC). METHODS: Calcitonin stimulation (calcium element 3 mg/kg weight, i.v. 10 min), carcino-embryonic antigen (CEA), gastrin (GST) and vasoactive intestinal peptide (VIP) were tested in 14 patients with postoperative MTC. SS-R imaging was used to localize the remnants after removal of MTC in patients with elevated calcitonin. RESULTS: Calcitonin stimulation test showed that the peak value of serum calcitonin was elevated in all patients, of whom 7 had the elevated vatue of basic calcitonin and peak calcitonin. In the 7 patients, SS-R imaging showed normal CEA, GST and VIP. CONCLUSIONS: It is necessary for patients after removal of MTC to perform calcitonin stimulation test for detecting remnants early. SS-R imaging may be useful for localizing remnants and metastatic foci. CEA, GST and VIP are not significant in monitoring MTC after operation.

Adult↗
PubMed2000

[Transposition of bilateral pedicled adrenal gland for the treatment of Cushing's disease].

OBJECTIVE: To study the therapeutic method of Cushing's disease. METHODS: 16 patients with Cushing's disease were treated by transposition of bilateral pedicled adrenal gland into the dorsal subcutaneous tissues. RESULTS: These patients were followed up for 4 to 48 months. No relapse was observed and 3 patients with hypoadrenocorticism were given small doses of steroid. CONCLUSIONS: This procedure may be a rational and satisfactory technique for the treatment of Cushing's disease.

Adolescent↗
PubMed2000

[An epidemiological study on acute diarrhea during a filed exercise in PLA unit in an area in southern China].

OBJECTIVE: To explore the epidemiological characteristics and risk factors of acute diarrheal disease during a filed exercise. METHODS: Epidemiological study of a certain artillery acute diarrheal disease during a filed exercise and multiple linear stepwise regression analysis, multiple stepwise discriminate analysis were used. RESULTS: Result showed that the incidence rate of training troops was significantly higher than that of the local troops at the corresponding period (7.32% vs 0.98% P<0.05). The incidence rate among officers was significantly lower than that of the soldiers (0.99% vs 8.20% P<0.05). The incidence rate was significantly higher at the beginning of assemble for training but smooth and steady afterwards with several outbreaks. There was highly significant difference in the incidence rate of 39 companies. Regression and discrimination analysis suggested that the incidence rate was correlated with the density of flies and average boiled water volume provided everyday. The correct classifying rate of the discrimination was 91.9% in total. CONCLUSION: These results provided a basis for prevention of acute diarrheal disease during filed exercise of military action.

Acute Disease↗
PubMed2000

[Screening and fermentation conditions of a bacterial strain over-producing xylanase].

A xylanase producer WXULI-11 was isolated and identified as Pseudomonas sp. By combination treatment of WXULI-11 with UV and NTG, a mutant WLUN024 was obtained and its enzyme activity reached 354 IU/mL in 36 h by shaking flask. The mechanism of its xylanase production was primarily studied. The results showed that this enzyme was induced by xylan, xylose and some other xylosic material, while xylose had "two-way effect" on xylanase synthesis. Effects of nitrogen and other factors on enzyme production were also investigated.

Culture Media↗
PubMed2000

[Expression of human papillomavirus DNA in cholesteatoma of the middle ear].

OBJECTIVE: To reveal the role of HPV in the occurrence and development of cholesteatoma of the middle ear. METHOD: PCR and nuclear acid hybridization were applied in screening 44 cases of middle ear cholesteatoma for detection of HPV DNA, and a comparison analysis with the pathological results of 35 cases of middle ear cholesteatoma was made. RESULTS: Pathologically, the characteristics of HPV induced-lesions was found in 12 of 35 specimens (34.3%). 44 cases of middle ear cholesteatoma were examined with consensus primers PCR and digoxigenin labeled HPV general probes. HPV DNA positive rates were 29.5% (13/44) and 25.0% (11/44) respectively. HPV DNA positive rate was 58.3% (7/12) and 13.0% (3/23) respectively in 12 cases with pathological characteristics of HPV induced-lesions and in 23 cases without those characteristics. There was significant difference(chi 2 = 7.926, P < 0.005). CONCLUSIONS: HPV infection can arouse the cleavage and proliferation of cholesteatoma epithelium and may play certain role in the occurrence and development of middle ear cholesteatoma. Aggressive, papillomatous growth and koilocytes can be served as the initial proof of HPV infection in cholesteatoma of the middle ear.

Adolescent↗
PubMed2000

Polymorphism of angiotensin-converting enzyme gene and genetic susceptibility to asthma with familial aggregation.

OBJECTIVE: Angiotensin-converting enzyme (ACE) plays a key role in the metabolism of angiotensin II (AT II) and inactivation of bradykinins and tachykinins, which are potent bronchialconstrictors and mediators of inflammation asthma, and ACE is heavily expressed in the lungs. An insertion-deletion (D/I) polymorphism of ACE gene has been shown to be associated with levels of ACE. We investigate whether the polymorphism of ACE gene is associated with asthma and bronchial responsiveness. METHODS: A case-control study was carried out in 50 asthmatics, 7 families with at least 2 asthmatic individuals, and 50 healthy subjects. The insertion/deletion (I/D) polymorphism of ACE gene was amplified by polymerase chain reaction (PCR). Methacholine brocho-provocation and pulmonary function tests were performed in all asthmatics. RESULTS. There was an higher gene frequency of DD genotype of ACE gene in asthmatic subjects and families individuals compared with healthy subjects (46%, 53% vs 16%, P<0.05; odd ratio 4.98). An- higher prevalence of DD genotype of ACE was in patients with bronchial hyperresposiveness (BHR) (67% vs 33%, P<0.05; odd ratio 3.8). Accordingly, the mean values of FEV1% and FEV1/FVC were higher in asthmatics carrying non-DD alleles than patients with DD genotype (73.78% vs 56.56%, P<0.05, 79.19% vs 69.29%, P<0.05, respectively). CONCLUSION: These results suggested that DD allele of ACE genotype was significantly involved in genetic susceptibility to asthma. DD genotype of ACE might be a risk factor for the degree of airway obstruction, it could also be implicated in pathogenesis of bronchial hyperresponsiveness.

Adolescent↗
PubMed2000

[A clinical study on coincidence with hyperthyroidism and thyroid carcinoma].

OBJECTIVE: A retrospective study has been carried out to evaluate the prevalence of coincidence with hyperthyroidism and thyroid carcinoma. METHODS: 394 patients underwent surgery for hyperthyroidism and 245 patients suffered from thyroid cancer were chosen for the study in our hospital from January 1983 to June 1998. RESULTS: Thyroid cancer and hyperthyroidism coincided in 12 patients. The incidence of thyroid cancer was 3.0% (12/394) in hyperthyroidism, and the incidence of hyperthyroidism was 4.9% in thyroid cancer. There were 7 female and 5 male, with a diffuse goiter (n = 3), a diffuse goiter with a cold nodule (n = 3), multinodular goiter (n = 6). Among the 12 patients, 7 patients had an occult thyroid cancer with a diameter of 1 cm or less, most of them with papillary carcinoma, less frequently had metastases, 4 patients had thyroid cancer with a diameter of 3 cm or more, and 3 patients had metastases. CONCLUSIONS: The prevalence of coincidence with thyroid cancer and hyperthyroidism is more than that of thyroid cancer in population. Diagnostics for exclusion of thyroid cancer is required carefully even in the presence of hyperthyroidism.

Female↗
PubMed1999

Intermolecular aggregations are responsible for the slow kinetics observed in the folding of cytochrome c at neutral pH.

Folding of equine cytochrome c at a low protein concentration (26 microM) eliminated a slow kinetic phase (time constant three seconds) that was observed in the previous hydrogen exchange pulse-labeling experiments at pH 6.2 and 10 degrees C. It was demonstrated that this slow folding phase was caused by intermolecular aggregations. Because heterogeneous kinetics is a very general feature in the folding of proteins characterized by pulsed hydrogen exchange coupled with two-dimensional NMR, our experimental results suggest aggregations might also be responsible for the complex folding kinetics of other proteins. This is possible since these experiments were performed at relatively high protein concentrations.

Amides↗
PubMed1999

Relationship between the native-state hydrogen exchange and the folding pathways of barnase.

The previous native-state hydrogen exchange experiment with barnase failed to detect any partially unfolded intermediate state which was contrary to the experimental results from kinetic deuterium hydrogen exchange pulse labeling and protein engineering studies. This has been taken to suggest that the native-state hydrogen exchange method cannot be used alone as an analytical tool to study the folding pathways of proteins. Here, we revisited the pulse labeling experiment with barnase and detected no stable folding intermediate. This finding allows a reconciliation of the native-state HX data and the folding pathway of barnase. Along with alternative theoretical interpretations for a curved chevron plot of protein folding, these data suggest that further investigation of the nature of the intermediate of barnase is needed.

Bacterial Proteins↗