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Biomedical subjects

Y L Chen

Publications and source records attributed to Y L Chen.

At least 91 records · Page 5Linked to original sources
PubMed1999

Survey of incisor trauma in second grade students of central Taiwan.

BACKGROUND: The purpose of this study was to investigate the prevalence and related factors of incisor trauma among 1200 second grade students in Taichung City, Taiwan. METHODS: The study population consisted of 1200 second grade students, 645 boys (53.8%) and 555 girls (46.3%), at four elementary schools in Taichung City, Taiwan. This survey was composed of two parts: (1) a questionnaire of dental traumatic history, and (2) a clinical examination of each subject to record any clinical evidence of traumatic dental injury on permanent incisors. RESULTS: The questionnaires indicated that 16.5% of the children had a positive history of dental trauma. The male to female ratio of a prior dental trauma was 1.4:1. The maxilla (78.2%) was affected more frequently than the mandible. Most of the injuries had occurred at home (63.7%). Clinical examinations disclosed that 3% of the subjects, 43 teeth in 37 children, had clinical signs and symptoms of dental trauma. Maxillary central incisors (77%) were the teeth most often affected. The most common type of crown injury was enamel fracture (67%). CONCLUSION: The prevalence of a history of dental trauma and clinical findings of incisor injury in this study was lower than that in previous reports. Home and school were the settings where dental injury was most likely to occur. Clinical signs and symptoms of dental trauma were found in 3% of the subjects. Maxillary incisors were the most commonly affected teeth, and 67% of these cases involved enamel fracture.

Age Factors↗
PubMed1999

Evaluation of serum CA27.29, CA15-3 and CEA in patients with breast cancer.

The Truquant BR radioimmunoassay (RIA) using monoclonal antibody BR 27.29 to recognize a peptide sequence on the MUC-1 gene product for quantification of the CA 27.29 antigen in serum was used in this report to evaluate in 145 patients with breast cancer and compared the other conventional serum markers such as CA15-3 and CEA. The upper limit of normal (25 u/ml) was determined from CA27.29 values 12.4 +/- 4.1 u/ml (mean +/- 3 S.D.) for 112 female subjects apparently free of disease. The CA15-3 levels above 25 u/ml and CEA levels above 5 ng/ml were considered positive values. Thirty-seven cases of 145 patients studied had elevated CA 27.29 levels (sensitivity: 25.5%), 35 of 145 had positive CA15-3 levels (sensitivity 24.1%) and 27 of 145 patients had positive CEA levels (sensitivity: 18.6%) (p < 0.05). One hundred and ten cases of the breast cancer patients (75.8%) did not have metastatic disease. In this group CA 27.29 sensitivity was 6.4%, while CA15-3 sensitivity was 5.5% and CEA sensitivity was 4.5% (p > 0.05). Mean values were 10.2 +/- 9.2 u/ml for CA 27.29, 14.1 +/- 5.6 u/ml for CA 15-3 and 1.7 +/- 1.5 ng/ml for CEA. Thirty-five patients (24.2%) had metastatic disease. In this group CA 27.29 sensitivity was 85.7%, CA15-3 sensitivity was 82.8% and CEA sensitivity was 62.8% (p < 0.05). Mean values for CA27.29 was 152.6 +/- 131.6 u/ml, CA15-3 was 123.1 +/- 107.6 u/ml and 21.8 +/- 36.9 ng/ml of CEA. With regard to the correlation of three tumor markers with clinical stages, patients had significantly higher levels of CA27.29 than CEA, but they were similar to CA 15-3 in metastatic breast cancer. These results suggest CA27.29 to be more sensitive and specific than CEA, but that it is similar to CA15-3 for metastatic breast cancer detection and monitoring.

Adult↗
PubMed1999

Relationship between hypertension and hearing disorders in the elderly.

OBJECTIVE: To investigate the relationship between hypertension and hearing disorders of the elderly. DESIGN: Prospective case-control study. SETTING: Lin Yi People's Hospital, Shandong Province, the People's Republic of China, from October 1995 to June 1997. PARTICIPANTS: Fifty five hypertensive patients and fifty five normal elderly subjects (control group) between the ages of fifty five and eighty nine years old were enrolled in the study. All patients were male and were divided into three groups according to age as follows: Group A: 55-64; Group B: 65-74; Group C: 75-89. INTERVENTIONS AND MAIN OUTCOME MEASURES: SIMENS DA-64 audiometer and MEDSON 2250 auditory brainstem response audiometry (ABR) were utilised to determine the degree of hearing disorders. Serum triglycerides and cholesterol were also tested in our central laboratory. RESULTS: Auditory thresholds collected during audiometric tests increased gradually in proportion with age, especially in the hypertensive group (p < 0.05). The results of the ABR demonstrated that the latencies of wave V, I-VIPL and III-VIPL were also prolonged compared with normal elderly subjects. The patient's duration of illness and the complications of hypertension had an influence on hearing disorders in relation to the ageing process. CONCLUSION: Hypertension, with a high level of blood triglycerides and cholesterol, worsens the hearing of the elderly. The hearing disorder in elderly people is a result of long duration of illness and the complications of the hypertension.

Age Distribution↗
PubMed1999

[Focal adhesion kinase].

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Focal Adhesion Protein-Tyrosine Kinases↗
PubMed1998

Synthesis and anticancer evaluation of certain gamma-aryloxymethyl-alpha-methylene-gamma-phenyl-gamma-butyrolactones.

Certain gamma-aryloxymethyl-alpha-methylene-gamma-phenyl- gamma-butyrolactones were synthesized and evaluated for their anticancer activity. These compounds demonstrated a strong growth inhibitory activity against leukemia cell lines but are relatively inactive against non-small cell lung cancers and CNS cancers. The anticancer potency for aryl portion is in an order of quinoline > 8-hydroxyquinoline > 2-methylquinoline >> naphthalene >> benzene.

4-Butyrolactone↗
PubMed1998

The induction of apoptosis by SV40 T antigen correlates with c-jun overexpression.

Simian virus (SV40) T antigen shares many characteristics with adenovirus E1A which is known to induce apoptosis. To verify the potential of SV40 T antigen-mediated apoptosis, we stably expressed T antigen in immortalized human epithelial cells (Z172 and HaCaT). We found that SV40 T antigen could directly cause apoptosis in 22-27% of these cells under normal growth condition as measured by chromatin condensation and nucleosomal fragmentation. The apoptosis of HaCaT cells which contain mutant p53 suggests the p53-independent nature of T antigen-mediated apoptosis. T antigen-induced apoptosis was associated with increased expression of c-Jun protein. Moreover, the overexpression of c-jun alone in these cells also induced apoptosis, indicating that c-jun might play an important role in T antigen-induced apoptosis.

Adenovirus E1A Proteins↗
PubMed1998

Mechanism of Nef-induced CD4 endocytosis: Nef connects CD4 with the mu chain of adaptor complexes.

The Nef protein of primate lentiviruses down-regulates the cell surface expression of CD4 and probably MHC I by connecting these receptors with the endocytic machinery. Here, we reveal that Nef interacts with the mu chains of adaptor complexes, key components of clathrin-coated pits. For human immunodeficiency virus type 2 (HIV-2) and simian immunodeficiency virus (SIV) Nef, this interaction occurs via tyrosine-based motifs reminiscent of endocytosis signals. Mutating these motifs prevents the binding of SIV Nef to the mu chain of plasma membrane adaptor complexes, abrogates its ability to induce CD4 internalization, suppresses the accelerated endocytosis of a chimeric integral membrane protein harboring Nef as its cytoplasmic domain and confers a dominant-negative phenotype to the viral protein. Taken together, these data identify mu adaptins as downstream mediators of the down-modulation of CD4, and possibly MHC I, by Nef.

Amino Acid Sequence↗
PubMed1998

Conformation of native, reduced and [5-55]Ala bovine pancreatic trypsin inhibitor in the gas phase.

Collision cross sections have been measured for gas phase ions of native oxidized bovine pancreatic trypsin inhibitor (BPTI), native reduced BPTI and a mutant form of BPTI containing a single disulphide bond between residues 5 and 55 ([5-55]Ala BPTI). Cross sections for [5-55]Ala BPTI and reduced BPTI were 9% and 17% greater respectively than those for native BPTI. Cross sections for native BPTI were smaller than previous estimates from the crystal structure but in reasonable agreement with values calculated from the radius of gyration determined by x-ray scattering from solution BPTI. The increase in cross section for reduced BPTI over native BPTI is similar to that seen in molecular dynamics simulations. The results show that the disulphide bonds of BPTI contribute to the folding of the gas phase ions, but that even in the absence of disulphide bonds the protein ions maintain compact structures. Comparisons to relative areas calculated from hydrodynamic radii of BPTI in solution suggest that when disulphide linkages are removed, BPTI in the gas phase unfolds less than BPTI in solution.

Amino Acid Substitution↗
PubMed1998

Stability of a highly charged noncovalent complex in the gas phase: holomyoglobin.

Gas phase holomyoglobin (hMb) ions in charge states +7 to +21 were formed by electrospray ionization in combination with a continuous-flow mixing apparatus. Collision cross section measurements show that the highly charged ions are somewhat unfolded in comparison to low charge states but still retain a considerable degree of folding. A new collision model is presented which calculates the relative energies transferred to complexes in tandem mass spectrometry. Tandem mass spectrometry and ion trapping experiments both show that the energies required to dissociate heme from the highly charged heme-protein complexes in the gas phase are similar to those of low charge states, previously shown in literature ion cyclotron resonance experiments to be 0.7-1.0 eV. These energies are comparable to those of the heme binding energy in solution. The results suggest that even for the highly charged hMb ions which have unfolded somewhat, the heme-protein interactions remain relatively unperturbed.

Animals↗
PubMed1998

Effects of shape and operation of chopsticks on food-serving performance.

The study evaluated the effects of six chopsticks designs on the food-serving performance of three tasks (food-pulling, food-pinching, and food-moving) under two different operations (pincers-pinching and scissors-pinching). A total of 40 male junior college students were employed as subjects for the laboratory experiment. Subjects who were experienced in pincers-pinching were superior in pinching precision and stability to those experienced in scissors-pinching. Nevertheless, the scissors-pinching group gave a more powerful pinching force while pulling the experimental food. Chopsticks with rounded handle and carved grooves on the tip were preferred in all the six experimental pairs. The research suggests that, in general, the pincers-pinching operation is recommended for daily food-serving and teaching children primary use of chopsticks. Therefore, chopsticks with rounded handle and carved grooves on the tip are suggested for family utensils (non-disposable chopsticks). Considering the cost and cleaning, chopsticks with rounded handle and square tip are recommended for general dining. However, the square handle and rounded tip chopsticks are the type most commonly used in Taiwan.

Adolescent↗
PubMed1998

Catalase prevents estradiol-induced chondrocyte cytotoxicity.

Osteoarthritis is a common geriatric disease and estrogen may play an important role in this disease. Estradiol may cause chondrocyte damage as suggested by in vitro and in vivo data. One of the possible mechanisms of estradiol-induced chondrocyte damage was thought to be related to free radicals. Whether catalase, a known free radical scavenger, can prevent estradiol-induced chondrocyte damage was tested using a chondrocyte culture system. The results of this study suggest that catalase can significantly reduce the estradiol-induced damage to chondrocytes. Apparently, catalase alters the molecular structure of estradiol as indicated by the absorption spectrum of estradiol with time. The modified estradiol may decrease its toxicity to the chondrocytes. However, the contents of free radicals in the treated chondrocytes have no significant difference from the untreated control cells. Studies to further investigate the mechanism or prevention of estradiol-induced chondrocyte damage in osteoarthritis are warranted.

Animals↗
PubMed1998

Local somatothermal stimulation inhibits the motility of sphincter of Oddi in cats, rabbits and humans through nitrergic neural release of nitric oxide.

To examine whether and how local somatothermal stimulation inhibits the function of the sphincter of Oddi (SO) in humans and in animals with different types of SO, we measured the activity of SO in anesthetized cats and rabbits by using continuously perfused open-tip manometric methods. Local somatothermal stimulation was achieved by applying an electroheating rod 0.5 cm away from the skin area near the right subcostal region. A heating pad was applied to the corresponding area in patients undergoing endoscopic retrograde cholangiopancreatography and biliary manometry. The motility of the biliary tract in cats, in terms of gall bladder pressure, tonic and phasic contraction pressure and frequency of SO before and during local heat were significantly different, respectively. The local heat-induced SO relaxation was not inhibited by pretreatment with atropine, propranolol, phentolamine or anti-cholecystokinin-octapeptide, but was almost completely blocked by infiltration of local anesthetics. Pretreatment with a nitric oxide synthesis inhibitor also blocked the relaxation, which was reversed by pretreatment with L-arginine, but not by D-arginine. The inhibition of SO motility by local heat in rabbits was also blocked by pretreatment with L-NAME, and this blockade was reversed by L-arginine. Application of local heat on patients demonstrated obvious inhibitory SO responses. We conclude that local somatothermal stimulation inhibits the SO motility in animals with different types of SO through the activation of heat-sensitive neural release of nitric oxide. This procedure may represent a simplified approach for the treatment of diseases with hypofunction of the L-arginine/NO pathway.

Animals↗
PubMed1998

The hemolymph clottable proteins of tiger shrimp, Penaeus monodon, and related species.

A clottable protein was purified from the hemolymph of tiger shrimp (Penaeus monodon) by sequential DEAE anion-exchange chromatography. The protein formed stable clots in the presence of Ca2+ and the transglutaminase in hemocyte lysate. It is thermostable at temperatures up to 66 degrees C. The molecular mass of the clottable protein was determined to be 380 kDa by SDS-PAGE and MALDI-TOF mass spectrometry, and the protein exists as disulfide-linked homodimers and oligomers. The size and amino acid composition of the clottable protein are similar to those of several other shrimps, prawns, lobster and crayfish, and their N-terminal amino acid sequences are 60-80% identical. Monosaccharide analysis of the clottable protein revealed the presence of mannose, glucosamine or N-acetylglucosamine and possibly glucose in this glycoprotein of about 5% sugar content. Lipid in the protein upon electrophoresis was hardly detectable with the Oil Red O staining method. In immunodiffusion and immunoblotting analyses, the anti-clottable protein antibodies reacted with the clottable proteins from the penaeid shrimps but not with those from other crustaceans.

Amino Acid Sequence↗
PubMed1998

Effect of combined dynamic and static workload on heart rate recovery cost.

The objective of the present study was to develop a simplified heart rate recovery cost (RC) model and to validate it under various degrees of dynamic and static task components. The simplified model of heart rate recovery cost consisted of two parameters: heart rate increase (delta HR) and recovery time (T). The following formula revealed their relationship: RC (recovery cost) = T x (delta HR-1)/ln delta HR Exercise, including cycling at three work loads (40, 60, 80 W) on a cycle ergometer, and carrying a backpack with three weights (0, 7.5, 15 kg) was studied in seven male subjects. For each exercise condition, resting HR, working HR, and recovery time (T) were recorded. The results support the hypothesis that neither heart rate increase nor recovery cost could completely assess the physical stress incurred when performing a combined dynamic/static exercise. The delta HR measurement was more sensitive to the increase of static load and the calculated RC value increased with both dynamic and static load. The simplified model of recovery cost can be easily applied without interfering with a person's work routine and without discomfort.

Adult↗
PubMed1998

The proteolytic cleavage of human immunodeficiency virus type 1 Nef does not correlate with its ability to stimulate virion infectivity.

The Nef protein of human immunodeficiency virus type 1 (HIV-1) promotes virion infectivity through mechanisms that are yet ill defined. Some Nef is incorporated into particles, where it is cleaved by the viral protease between amino acids 57 and 58. The functional significance of this event, which liberates the C-terminal core domain of the protein from its membrane-associated N terminus, is unknown. To address this question, we examined the modalities of Nef virion association and processing. We found that although significant levels of Nef were detected in HIV-1 virions partly in a cleaved form, cell-specific variations existed in the efficiency of Nef proteolytic processing. The virion association of Nef was strongly enhanced by myristoylation but did not require other HIV-1-specific proteins, since Nef was efficiently incorporated into and cleaved inside murine leukemia virus particles. Substituting alanine for tryptophan57 decreased the efficiency of Nef processing, while mutating leucine58 had little effect. In contrast, replacing both of these residues simultaneously almost completely prevented this process. However, when the resulting mutants were compared with a wild-type control in viral infectivity assays, no correlation was found between the levels of cleavage and the ability to stimulate virion infectivity. Furthermore, simian immunodeficiency virus Nef, which lacks the sequence recognized by the protease and as a consequence is not cleaved despite its incorporation into virions, could stimulate the infectivity of a nef-defective HIV-1 variant as efficiently as HIV-1 Nef. On these bases, we conclude that the proteolytic processing of Nef is not required for the ability of this protein to enhance virion infectivity.

Binding Sites↗
PubMed1998

Coactivator TIF1beta interacts with transcription factor C/EBPbeta and glucocorticoid receptor to induce alpha1-acid glycoprotein gene expression.

The transcription of the alpha1-acid glycoprotein gene is induced by inflammatory cytokines and glucocorticoids. C/EBPbeta is a major transcription factor involved in the induction of the agp gene by some cytokines. In this report, we have identified a novel transcriptional intermediary factor, TIF1beta, which could enhance the transcription of the agp gene by the glucocorticoid receptor (GR) and C/EBPbeta. TIF1beta belongs to a subgroup of RING (really interesting new gene) finger proteins that contain a RING finger preceding two B box-type fingers and a putative coiled-coil domain (RBCC domain). Immunoprecipitation experiments showed that the interaction between GR and TIF1beta is ligand independent. The overexpression of the TIF1beta gene enhances GR-regulated expression in a ligand- and glucocorticoid-responsive element (GRE)-dependent manner. TIF1beta can also augment C/EBPbeta-mediated activity on wild-type and GRE-mutated agp genes, but this augmentation is diminished when all three C/EBPbeta-binding elements are mutated. Functional and biochemical characterizations indicated that the bZIP domain of C/EBPbeta and the RBCC domain, plant homeodomain finger, and bromodomain of TIF1beta are crucial for the interactions of these proteins. Taken together, these results suggest that TIF1beta serves as a converging mediator of signal transduction pathways of glucocorticoids and some inflammatory cytokines.

Animals↗
PubMed1998

A mouse model of mosquito allergy for study of antigen-specific IgE and IgG subclass responses, lymphocyte proliferation, and IL-4 and IFN-gamma production.

To date, there are no ideal animal models for study of natural sensitization leading to IgE- and lymphocyte-mediated hypersensitivities. We established such a model in which four BALB/c mice were each sensitized by exposure to at least 16 mosquito Aedes aegypti bites, twice a week for 4 weeks. Four non-exposed control mice were also studied. Mosquito A. aegypti head and thorax extract, saliva, and two recombinant salivary allergens (rAed a 1 and rAed a 2) were used in vitro as antigens. Intradermal tests were performed. Serum mosquito antigen-specific IgG, IgG1, IgG2a, and total IgE were measured by ELISA; specific IgE was measured by passive cutaneous anaphylaxis (PCA). IgE responses to each antigen in the saliva were analyzed using Western blotting. Spleen lymphocyte proliferation assays were performed to determine the cell-mediated hypersensitivity response. Antigen-induced IL-4 and IFN-gamma production in the spleen lymphocytes were evaluated using ELISA. After 4 weeks, all 4 mosquito-sensitized mice developed a positive immediate wheal 20 min after skin tests with mosquito antigens, and a positive delayed papule 24 h later, while control mice did not. Also, the sensitized mice had a positive PCA response, which correlated significantly with total IgE levels (r = 0.84, p<0.05), confirming the presence of antigen-specific IgE, while none of control mice had a positive response. Antigen-specific IgG1, but not IgG2a, was increased in the sensitized mice (p<0.01). Western blotting showed that 5 of the 8 antigens which elicited mouse IgE responses, including 2 major antigens, also elicited human IgE responses. The mean lymphocyte proliferation response to mosquito antigens also elicited human IgE responses. The mean lymphocyte proliferation response to mosquito antigens was significantly increased in the sensitized mice (p<0.05). IL-4 production was significantly increased and IFN-gamma production was decreased, further suggesting that a Th2 immune response predominates despite the development of the delayed skin reaction. This new model of natural sensitization without using an adjuvant is potentially useful for the study of other allergic disorders as well as mosquito allergy.

Allergens↗