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Biomedical subjects

Y Bai

Publications and source records attributed to Y Bai.

At least 55 records · Page 3Linked to original sources
PubMed2001

Study of iron metabolism abnormality in the hepatocyte damage of hepatitis B.

OBJECTIVE: To study the effect of iron metabolism on patients with hepatitis B. METHODS: Hemoglobin (Hb), serum ferritin (SF), transferritin (TRF), serum iron (SI), and total iron binding capacity (TIBC) were detected in 103 patients with hepatitis B and 20 healthy adults. RESULTS: The severer the hepatocyte damage was, the higher the SF, SI and the lower the Hb, TRF, and TIBC were. Furthermore, it seems more obvious among fulminant hepatitis and liver cirrhosis. CONCLUSIONS: The overload of iron may enhance the hepatocyte damage induced by HBV. Therefore, to detect serum markers of iron metabolism is helpful to evaluate curative effect and prognosis of hepatitis B.

Adolescent↗
PubMed2001

[The establishment of three-dimensional soft tissue facial reconstruction and morphometry].

OBJECTIVE: To establish a digital three-dimensional facial soft tissue morphometry and reconstruction system for orthodontic diagnosis and analysis of the facial soft tissue. METHODS: Three-dimensonal characteristics of facial soft tissue were captured by 4 digital cameras of high resolution. The developed hardware and software system and stereophotogrammetry were used for three-dimensional facial soft tissue reconstruction and morphometry at the same time. RESULTS: The three-dimensional facial soft tissue were successfully reconstructed with high reality and the three dimensional facial image can be rotated, moved and zoomed on the purpose. The system has the following advantages: (1) rapid capture of the facial image within 1 second or so, (2) accurate identification of facial landmark within 0.5 mm of resolution, (3) easy manipulation, (4) no exposure to radiation. CONCLUSIONS: The established system has proved to be effective for three-dimensional facial soft tissue diagnosis and analysis with the advantages of high resolution, high speed and, no exposure to radiation.

Face↗
PubMed2001

Analysis of the T cell receptor V delta region gene repertoire in bronchoalveolar lavage fluid (BALF) and peripheral blood of asthmatics.

OBJECTIVE: To explore the role of gamma delta T cells in the airway of asthmatics and to identify the forces which induce and maintain the inflammatory process. METHODS: Peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) were obtained from 7 asthmatic subjects and 7 nonsmoker control subjects. The percentage of gamma delta T cells in the PB and BALF was measured by immunofluorescent staining and flow cytometry. The frequency of usage and the clonality of V delta subfamilies (V delta 1-V delta 3) were assessed by RT-PCR and gene scanning. RESULTS: A higher proportion of gamma delta T cell was detected in the BALF of asthmatic subjects (7.8% +/- 4.7%) than that from control subjects (3.3% +/- 3.0%, P = 0.04). No selective usage for a particular V delta subfamily was found, but the relative expression level of V delta 1 was significantly higher in the asthmatic airway (44% +/- 13%) than in the control (19% +/- 5%, P = 0.0002). In asthmatic subjects, the monoclonal or oligoclonal expansion of gamma delta T lymphocytes was predominant in the BALF, especially V delta 1+ T lymphocytes. CONCLUSIONS: Antigenic specific gamma delta T cells might play an important role in the inducement and maintenance of airway inflammation. Persistent antigenic stimulation may be the key factor that maintains chronic airway inflammation in asthma.

Adult↗
PubMed2001

[Analysis of the T cell receptor Vdelta region gene repertoire in asthmatic subjects].

OBJECTIVE: To explore the role of gammadelta T cells in the asthmatic airway inflammation and identify the forces which induce and maintain the inflammatory process. METHODS: Peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) were obtained from seven asthmatic subjects and seven nonsmoking control subjects. The percentage of gammadelta T cells in PB and BALF were measured by immunofluorescent staining and flow cytometry, the frequency of usage and the clonality of Vdelta subfamilies (Vdelta(1) approximately Vdelta(3)) were assessed by RT-PCR and gene scanning. RESULTS: Higher proportion of gammadelta T cell was detected in the BALF of asthmatic subjects [(7.8 +/- 4.7)%] than that from control subjects [(3.3 +/- 3.0)%] (P < 0.05) and the relative expression level of Vdelta(1) significantly higher in the asthmatic airway [(44 +/- 13)%] than in the control group [(19 +/- 5)%] (P = 0.002). In asthmatic subjects, the monoclonal or oligoclonal expansion of gammadelta T lymphocytes was predominant in BALF, especially Vdelta(1) T lymphocytes. CONCLUSIONS: Antigenic specific gammadelta T cells might play important roles in the inducement and maintenance of airway inflammation.

Adult↗
PubMed2001

[A survey of pollens in Chongqing].

OBJECTIVE: In order to investigate the variety of the airborne pollen in Chongqing. METHOD: The diffusions pattern of airborne pollens in two areas of Chongqing was investigated for one year from October 1999 to September 2000. The slides were exposed daily through one year. RESULT: The peak of spreading was in March in spring and in Autumn from September to October. The test on the pollen patients shows that the main resulting pollen is in Autumn. CONCLUSION: The airborne pollen peak in Chongqing in spring prone to the influence of temperature, wind power and rain amount.

Allergens↗
PubMed2000

A bis-cyclodextrin diselenide with glutathione peroxidase-like activity.

A diselenide, 2,2'-diseleno-bis-beta-cyclodextrin (2-SeCD), was synthesized to imitate the antioxidant enzyme glutathione peroxidase (GPX). The GPX mimic accepts a variety of hydroperoxides as substrates. The GPX activities, reduction of H(2)O(2), tert-butyl hydroperoxide and cumenyl hydroperoxide by glutathione, are 7.4, 4.5 and 10.2 U/micromol, respectively. In contrast to ebselen (PZ51), the diselenide displays high GPX-like activity. The reduction of hydroperoxide by glutathione in the presence of a radical trap shows that the mimic catalyzes the reaction via a non-radical mechanism. A ping-pong mechanism was observed in the steady-state kinetic studies of the 2-SeCD-catalyzed reaction.

Animals↗
PubMed2000

Absence of stable intermediates on the folding pathway of barnase.

Barnase is one of the few protein models that has been studied extensively for protein folding. Previous studies led to the conclusion that barnase folds through a very stable submillisecond intermediate ( approximately 3 kcal/mol). The structure of this intermediate was characterized intensively by using a protein engineering approach. This intermediate has now been reexamined with three direct and independent methods. (i) Hydrogen exchange experiments show very small protection factors ( approximately 2) for the putative intermediate, indicating a stability of approximately 0.0 kcal/mol. (ii) Denaturant-dependent unfolding of the putative intermediate is noncooperative and indicates a stability less than 0.0 kcal/mol. (iii) The logarithm of the unfolding rate constant of native barnase vs. denaturant concentrations is not linear. Together with the measured rate ("I" to N), this nonlinear behavior accounts for almost all of the protein stability, leaving only about 0.3 kcal/mol that could be attributed to the rapidly formed intermediate. Other observations previously interpreted to support the presence of an intermediate are now known to have alternative explanations. These results cast doubts on the previous conclusions on the nature of the early folding state in barnase and therefore should have important implications in understanding the early folding events of barnase and other proteins in general.

Bacterial Proteins↗
PubMed2000

Hypermodification of tRNA in Thermophilic archaea. Cloning, overexpression, and characterization of tRNA-guanine transglycosylase from Methanococcus jannaschii.

tRNA is structurally unique among nucleic acids in harboring an astonishing diversity of modified nucleosides. Two structural variants of the hypermodified nucleoside 7-deazaguanosine have been identified in tRNA: queuosine, which is found at the wobble position of the anticodon in bacterial and eukaryotic tRNA, and archaeosine, which is found at position 15 of the D-loop in archaeal tRNA. From homology searching of the Methanococcus jannaschii genome, a gene coding for an enzyme in the biosynthesis of archaeosine (tgt) was identified and cloned. The tgt gene was overexpressed in an Escherichia coli expression system, and the recombinant tRNA-guanine transglycosylase enzyme was purified and characterized. The enzyme catalyzes a transglycosylation reaction in which guanine is eliminated from position 15 of the tRNA and an archaeosine precursor (preQ(0)) is inserted. The enzyme is able to utilize both guanine and the 7-deazaguanine base preQ(0) as substrates, but not other 7-deazaguanine bases, and is able to modify tRNA from all three phylogenetic domains. The enzyme shows optimal activity at high temperature and acidic pH, consistent with the optimal growth conditions of M. jannaschii. The nature of the temperature dependence is consistent with a requirement for some degree of tRNA tertiary structure in order for recognition by the enzyme to occur.

Amino Acid Sequence↗
PubMed2000

Human interferon-beta inhibits binding of HIV-1 gp41 to lymphocyte and monocyte cells and binds the potential receptor protein P50 for HIV-1 gp41.

Previous findings have indicated that HIV-1 gp41 like human type I interferon (IFN) could inhibit lymphocyte proliferation and up-modulate MHC class I, II and ICAM-1 molecule expression, and a common epitope exists between gp41 and type I interferon (IFN-alpha and -beta) in the receptor binding regions. To clarify the relationship between human type I interferon and HIV-1 gp41, we tried to inhibit recombinant soluble gp41-binding to human T, B and monocyte cell lines by human IFN-alpha, -beta and -gamma. It was interestingly observed that IFN-beta after preincubating with cells could inhibit the binding of rsgp41 to H9, Raji and U937 cells (T, B and monocyte cell lines), while this binding could not be inhibited by another type I interferon (IFN-alpha) and a type II interferon (IFN-gamma). It was further examined whether human IFN-alpha and -beta bind to the gp41 binding protein P50. In ELISA-assay, the human IFN-beta, but not IFN-alpha, could bind to P50 which was identified as a potential cellular receptor protein for gp41-binding. By the affinity capillary electrophoresis (ACE) analysis, formation of stable IFN-beta-P50 complex was observed. These results indicate that IFN-beta binds the potential receptor protein P50. Based on these experimental evidences and previous studies, it was presumed that the potential cellular receptor protein P50 may be the 51 kDa subunit of human IFN-alpha/beta receptor, which needs to be verified in the future.

Cell Line↗
PubMed2000

Bias associated with study protocols in epidemiologic studies of disease familial aggregation.

The effect of selection bias has not been well evaluated in epidemiologic studies which focus on familial aggregation. The authors illustrate this type of bias for a reconstructed cohort study. With the reconstructed cohort design, cases and controls are first selected from the population and their relatives form the exposed and unexposed cohorts, respectively. The recurrence risk ratio (RRR) is calculated to assess and measure familial aggregation. The ways of utilizing information from relatives affects the estimate of RRR, and the authors show that a traditional method used in epidemiologic studies can yield a severely biased estimate of the RRR. However, this traditional approach can give approximately unbiased estimates under special conditions. A novel selection approach is proposed which yields an unbiased estimate of RRR. In conclusion, when relatives are identified through cases or controls, they should be included and counted in the study cohorts each time a case or control is selected, even if they or other family members have already been included.

Bias↗
PubMed2000

Distinct expression of CDX2 and GATA4/5, development-related genes, in human gastric cancer cell lines.

CDX2 is a tumor-suppressor homeobox gene involved in colon carcinogenesis, but its role in gastric cancer is unknown. Although GATA4, -5 and, -6 transcription factors have distinct functions in the regulation of gastrointestinal epithelial cell differentiation, there have been no reports regarding GATA4/5/6 alterations in gastrointestinal carcinomas. By using a semiquantitative reverse transcription-polymerase chain reaction assay, we studied the expression of gut development-related genes CDX2/1 and GATA4/5/6 in 11 human gastric cancer cell lines. The expression of CDX2 appeared to progressively decrease with the transition from well differentiated to poorly differentiated cancer cell lines. CDX1 was below detectable levels in all cell lines. The expression of GATA4 and GATA5 was undetectable in four and six cell lines, respectively, whereas the majority of the cell lines expressed GATA6 abundantly. These results suggest that CDX2 and GATA4/5 may be associated with the carcinogenesis of the stomach. Mol. Carcinog. 28:184-188, 2000.

Adenocarcinoma↗
PubMed2000

DNA/dendrimer complexes mediate gene transfer into murine cardiac transplants ex vivo.

Starburst polyamidoamine dendrimers are synthetic polymers with unique structural and physical characteristics suitable for DNA gene transfer. Our previous studies demonstrated that Starburst dendrimers augment plasmid-mediated gene transfer efficiency in a nonvascularized, cardiac transplantation model. In this study, the fifth generation of ethylenediamine core dendrimer was investigated for its ability to enhance gene transfer and expression in a clinically relevant murine vascularized heart transplantation model. The plasmid pMP6A-beta-gal, encoding beta-galactosidase (beta-Gal), was incubated with dendrimers to form complexes. The complexes were perfused via the coronary arteries during donor graft harvesting, and reporter gene expression was determined by quantitative evaluation of X-Gal staining. The grafts infused with pMP6A-beta-gal/dendrimer complexes showed beta-Gal expression in myocytes from 7 to 14 days. A number of variables for transfer of the DNA/dendrimer complexes were tested, including DNA:dendrimer charge ratios, concentrations of DNA and dendrimer, preservation solutions, ischemic time, and enhancement of vascular permeability by serotonin, papaverine, and VEGF administration. The results showed that DNA/dendrimer complexes containing 20 microg of DNA and 260 microg of dendrimer (1:20 charge ratio) in a total volume of 200 microl resulted in highest gene expression in the grafts. The results also showed that prolonged incubation (cold ischemic time) to 2 h and pretreatment with serotonin further enhanced gene expression.

Animals↗
PubMed2000

Quality of life for children with fecal incontinence after surgically corrected anorectal malformation.

PURPOSE: The aim of this study was to investigate influences of fecal incontinence on children's quality of life after surgically corrected anorectal malformation. METHODS: Seventy-one children with anorectal malformation underwent follow-up for 8 to 16 years postoperatively. They were divided into good, fair, and poor groups by assessment of anal function. The quality of life was investigated by self-structured disease impact questionnaires and Achenbach's Child Behavior Check List (CBCL). A quality-of-life scoring criteria was established to assess quality of life of the 71 children with operated anorectal malformation and controls. RESULTS: Owing to fecal incontinence, 12 (16.9%) children reported that there were problems in peer relationships; school absences happened in 13 (18.3%) children; 17 (23.9%) children had to restrict themselves to certain food. Based on CBCL, 13 (18.3%) children had behavior problems. The behavior problems in children with poor fecal continence (66.7%) were significantly higher than those of children with good fecal continence (8.6%). According to the quality-of-life scoring criteria, the scores of children with operated anorectal malformation (9.4+/-3.7) were significantly lower than those of the controls (11.2+/-0.9). The scores of children with poor fecal continence (4.8+/-1.4) were significantly lower than those of children with good fecal continence (10.9+/-1.2). CONCLUSIONS: The children with poor fecal continence have poor quality of life caused by fecal dysfunction. Attention should be paid to the rehabilitation of fecal continence after surgery, such as bowel training and biofeedback therapy. The somatic and psychological care and long-term follow-up are necessary to improve the quality of life.

Adolescent↗
PubMed2000

Expressions of leptin and insulin-like growth factor-I are highly correlated and region-specific in adipose tissue of growing rats.

OBJECTIVE: Anatomically distinct adipose tissue regions differ in their predominant modality of growth (i.e., cellular hypertrophy vs. hyperplasia). We examined site-specific patterns of expression of two genes whose products, leptin and insulin-like growth factor-I (IGF-I), could be involved in mediating differential growth and metabolism of white adipose tissue. We also related these patterns of expression to measures of adipose depot cellularity. RESEARCH METHODS AND PROCEDURES: Male Wistar rats were fed ad libitum and studied from ages 7 weeks to approximately 12 months. Terminal measures of body weights; weights, composition, and cellularity of four white adipose depots; circulating leptin and IGF-I; and adipose depot-specific expression levels of leptin and IGF-I were measured in subsets of rats at 7, 12, 22, 42, and 46 weeks of age. RESULTS: Both leptin and IGF-I mRNAs are quantitatively expressed in a depot-specific manner, in the following order: retroperitoneal approximately equals epididymal > mesenteric > subcutaneous inguinal. Furthermore, there is a marked correlation between the expressions of these hormones in the various regions of adipose tissue of rats during the first year of life. The mechanisms that underlie the parallel expressions of leptin and IGF-I appear to be related to fat-cell volume. DISCUSSION: Because both leptin and IGF-I have been implicated in the regulation of energy homeostasis and are both expressed in adipose tissue, the depot-specific linkage between the two genes suggests interaction at the autocrine level. This interaction may have an important role in determining functional properties particular to individual adipose depots.

Adipose Tissue↗
PubMed2000

Neural electrophysiological studies on the external anal sphincter in children with anorectal malformation.

BACKGROUND/PURPOSE: Abnormality of innervation of external anal sphincter is one of the most important factors affecting postoperative anorectal function. The abnormalities of lumbosacral nerves have been reported in many radiological and histopathologic studies. There are few reports on the neurophysiological changes in children with anoractal malformation. The aim of this study was to examine the functional changes of nerves to the external anal sphincter in anorectal malformation. METHODS: Forty-five patients with anorectal malformation underwent studies of latencies of pudendo-anal reflex, spinoanal response, and evoked potential of cauda equine simultaneously. The conduction time of afferent nerve, efferent nerve, and sacral spinal center of pudendo-anal reflex arc were analyzed quantitatively. RESULTS: The latencies of pudendo-anal reflex, spino-anal response, and conduction time of sacral spinal center significantly are prolonged in patients with anorectal malformation (P< .05). There was significant difference between rectourethral fistula group and vestibular fistula group as well as low-type deformity group. The patients with lumbosacral anomalies such as lumbosacral spinal bifida or absence of S4 or S5 had prolonged latencies, especially the pudendo-anal reflex latency. There was significant negative correlation between the latencies and clinical scores. Although pudendoanal reflex latency was longer in patients who had posterior sagittal anorectoplasty than those who had abdominoperineal pull-through procedure, the difference was not significant. CONCLUSIONS: The abnormality of nerves to external anal sphincters is one of the important causes for clinical outcome. The neural lesions vary in each type of anal and lumbosacral deformity.

Adolescent↗
PubMed2000

Kinetic evidence of an on-pathway intermediate in the folding of lysozyme.

By means of a kinetic test, it was demonstrated that one of the folding intermediates (Ialpha) of hen lysozyme with alpha-domain folded and beta-domain unfolded is on the folding pathway under the classical definition. Ialpha folds to the native (N) state directly (unfolded (U) <==> Ialpha <==> N) without having to unfold to U and then refold to N through alternative folding pathways as in Ialpha <==> U <==> N.

Animals↗
PubMed2000

Induction of high levels of epitope-specific antibodies by epitope/peptide candidate vaccines against human immunodeficiency virus type-1 (HIV-1).

To test the immunogenicity of GPGRAFY-epitope-based candidate vaccines, a peptide with four repetitive GPGRAFY epitopes, V3-P1 [C-(GPGRAFY)4], and a peptide (PND) of the principal neutralizing domain (V3 loop: amino acid 301-328: C-TRPNNNTRKSIRIQRGPGRAFYTIGKI) on gp120 were synthesized and covalently coupled to a carrier protein BSA. Immunization of BALB/c mice and New Zealand White Rabbits with these conjugate vaccines engendered strong antibody responses against the PND (mouse serum titer by 1:12,800-25,600; rabbit serum titer by 1:6,400-12,800). Interestingly, the V3-P1-BSA conjugates and the PND-BSA conjugates could induce high levels of GPGRAFY-epitope-specific antibodies in the mice and rabbits (mouse serum titer by 1:25,600; rabbit serum titer by 1:12,800-25,600), while a recombinant gp160 subunit vaccine induced a low level of GPGRAFY-epitope-specific antibodies (serum titer by 1:400-1,600 in mice and rabbits). To confirm the above results, GPGRAFY-epitope-specific antibodies were isolated from rabbit sera induced by V3-P1-BSA, PND-BSA conjugates and rgp160 vaccine. In fact, 23-38 and 13-22 microg epitope-specific antibodies per milliliter serum were isolated from rabbit sera induced by V3-P1-BSA and PND-BSA conjugate, respectively, while 1.34 microg epitope-specific antibodies per milliliter serum were identified in rabbit serum induced by rgp160 vaccine. In the control group, only 0.069 microg proteins per milliliter serum were found in pooled pre-immune serum (normal serum). These results from mouse and rabbit experiments indicate that epitope and peptide vaccines both induce high levels of GPGRAFY-epitope-specific antibodies in comparison with rgp160 subunit vaccine, suggesting that epitope/peptide vaccines may be a new strategy to induce protective activity.

AIDS Vaccines↗