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Biomedical subjects

Y Luo

Publications and source records attributed to Y Luo.

At least 235 records · Page 13Linked to original sources
PubMed1999

[Comparative study of the effect on stress distribution of porcelain laminate complex with different elastic moduli].

Porcelain laminate has been a kind of popular treatment modality for its aesthetics and less tooth reduction. The models of 3-D FEA of left upper permanent central incisor were designed by microtomy. Comparative studies of stress distribution were carried out to reveal the stress of three designs of tooth preparation with two kinds of occlusions. The results showed that under loads imitating of central occlusion, the stress level increased a little with the rising of elastic modulus of the porcelain material, while the stress values of type II veneer seemed the highest under loads imitating of protruding occlusion. For the designing of laminate, it implies that porcelain material with low elastic modulus should be used in case of type II veneers.

Dental Porcelain↗
PubMed1999

[A study on the quality criteria for wushicha capsules].

OBJECTIVE: To build up the quality criteria for Wushicha capsules. METHOD: Rhizoma Atractylodis, Cortex Magnoliae Officinalis, Rhizoma Chuanxiong, Herba Pogostemonis in Wushicha capsules were identified by TLC. The contents of magnolol in the preparation were determined by GC. RESULT: These methods are simple and accurate. CONCLUSION: These methods can be used for the quantitative analysis of Wushicha capsules.

Asteraceae↗
PubMed1999

[A study on digestion of Gal alpha (1,3) Gal on porcine vascular endothelial cells by alpha-galactosidase].

This study was designed to explore ways to prevent immune rejection in xenotransplantation. Porcine vein endothelial cells treated by alpha-Galactosidase were used to investigate the expression of Gal alpha(1,3) Gal on porcine vascular endothelial cells, and the morphology of vascular endothelial cells. The results showed that Gal alpha (1,3) Gal (alpha-Gal) on porcine vascular endothelial cells, which is the major epitome of xenoantigen, could be digested by alpha-Galactosidase within 30 minutes. No morphological changes were observed in the porcine vascular endothelial cells within a period of one hour after the treatment. This suggested that the treatment of porcine tissues with alpha-Galactosidase could be a new and effective way to prevent hyperacute rejection after xenotransplantation.

Animals↗
PubMed1999

[Spreading depression and cerebral ischemia].

Growing evidence indicates that spreading depression (SD) may not only relate to some diseases, including cerebral ischemia, migraine, epilepsy, traumatic brain injury and so on, but also affect the physiological courses such as sleep patterns and general arousal. In this paper we review the relationship between SD and cerebral ischemia. The following questions are discussed: (1) The discovery of SD and its brief research history; (2) SD in the intact brain; (3) Peri-infarct SD in focal cerebral infarction. It is suggested that peri-infarct SD contributes to the growth of focal ischemic lesions, and the suppression of SD may become a novel, even a key therapeutic approach for minimizing infarct volume and protecting ischemic neurons after focal cerebral ischemia.

Animals↗
PubMed1999

[Study of the distribution and migration laws of nitroglycerin in energy increasing propellant by size exclusion chromatography].

It is very important to increase the energy of high-nitrogen-content single-base propellant by absorbing nitroglycerin in the case of keeping the advantage of the original propellant. In this paper, the distribution laws and migration laws in the aging of nitroglycerin have been studied by size exclusion chromatography (SEC) after high-nitrogen-content single-base propellant absorbing nitroglycerin. The results show that the distribution of nitroglycerin in high-nitrogen-content sigle-base propellant follows the Gauss distribution. In aging, this distribution changes towards the big variance Gauss distribution. The relationship between migration mass and aging time is y = k1e-k2/t, for external layer k1 = 0.1208 and k2 = 17.229, for inner hole k1 = 0.0348 and k2 = 10.97. The migration velocity constant, K = A0e-E/RT, of nitroglycerin is also given in this article, where A0 = 0.4086 and E0 = 1.6702 kJ/mol for inner hole, A0 = 31.2775 and E0 = 3.5428 kJ/mol for external layer.

English Abstract↗
PubMed1999

[Activated T lymphocytes in epiretinal membranes from eyes of patients with proliferative diabetic retinopathy].

PURPOSE: To investigate the potential contribution of immune-mediated processes to the development of proliferative diabetic retinopathy(PDR), an immunohistochemical study was undertaken to characterize the infiltrating immune cells in epiretinal membrances from the eyes of patients with PDR. METHODS: A total of 15 PDR epiretinal membrane specimens obtained surgically from pars plans vitrectomy were studied by using a panel of monoclonal antibodies against T lymphocytes (CD4), interleukin-2(IL-2) and interleukin-2 recpetors(IL-2R). RESULTS: Twelve of 15 specimens (80%) contained CD4-positive cells. IL-2 was found in 12 of 15 samples (80%), of which 11 also contained CD4-positive cells, and IL-2R was detected in 10 of 15 membranes(67%), of which 9 contained CD4-positive cells and released IL-2. Most of the IL-2R-positive membranes were from type I diabetic patients, 40% of them are younger than 40 years. CONCLUSION: Our study demonstrated the involvement of activated immune cells and release of lymphokine(s) in more than half of the diabetic epiretinal membranes tested and revealed that the processes of immune responses and the biological effects of lymphokines(s) may play an important part in the development of epiretinal membranes of PDR, especially in young-onset and type I diabetes.

CD4 Antigens↗
PubMed1999

Effects of musical meditation training on auditory mismatch negativity and P300 in normal children.

The auditory mismatch negativity (MMN) and P300 of event-related potentials were compared in normal children either with or without musical meditation training. The experimental group consisted of 11 subjects who had been trained with musical meditation for six months and the control group consisted of 12 subjects (matched for age, sex and grade) who had not received musical meditation. MMN amplitudes in the trained children were larger than those in the control group. In addition, the MMN amplitudes were identical in attend and ignore conditions for both groups. This evidence suggests that auditory brain function has been affected by musical meditation training. It thus suggests that the MMN is capable of assessing changes to the brain function in normal subjects. There were no significant differences in the P300 latencies and amplitudes between the two groups. This result suggests that MMN and P300 may reflect different aspects of the brain function.

Acoustic Stimulation↗
PubMed1999

Study of loss of heterozygosity at DCC and APC/MCC genetic loci of gastric cancer.

In order to assess the role of the changes of DCC and APC/MCC genes in the development and progression of gastric cancer, the loss of heterozygosity (LOH) of these genetic loci was investigated in 45 surgical specimens of gastric cancer with PCR-RFLP. The rate of LOH was 30.0% (9/30) at APC/MCC gene and 33.3% (15/45) at DCC gene. LOH was found in both intestinal and gastric types of gastric cancer and the rate of LOH of DCC gene was significantly higher in stages III to approximately IV gastric cancer (48.0%) than in stages I to approximately II (15.0%) (P<0.05). LOH of APC/MCC gene could be found in both early and advanced stages of gastric cancer. These findings suggest that changes of DCC and APC/MCC genes are involved in the development and progression of the intestinal and gastric types of gastric cancer.

Adenocarcinoma↗
PubMed1999

[Study on spectral emission characteristics of infrared lamps].

The spectral characteristics at wavelength ranges of 0.35-0.85 microm and 1.72-16.7 microm (5800-600 cm(-1)) for both domestic and imported infrared lamps used in scientific research, industry, medical service, home electrical appliance etc. have heen studied and compared. This paper has provided the theoreical and experimental bases for their applications and improvement in designs, technology of manufacture, quality and performance.

English Abstract↗
PubMed1998

Molecular cloning and expression of human grap-2, a novel leukocyte-specific SH2- and SH3-containing adaptor-like protein that binds to gab-1.

The SH2- and SH3-containing adaptor molecules serve to recruit cytosolic signal-transducing molecules to the activated receptor tyrosine kinases. In this study, we report the molecular cloning of a novel adaptor-like protein, Grap-2 (Grb-2 related adaptor protein 2), using the multisubstrate docking protein Gab-1 as bait in the yeast two-hybrid system. Sequence analysis revealed that Grap-2 contains a SH3-SH2-SH3 structure that has a high degree of sequence homology to those of the Grb-2 and Grap adaptor molecules. However, unlike in Grap and Grb-2, the SH2 and the C-terminal SH3 domains of Grap-2 are separated by a 120-amino-acid glutamine-rich sequence that shows no apparent homology to any known molecule or structural motif. The C-terminal SH3 domain of Grap-2 alone is sufficient to bind to Gab-1. Furthermore, Northern blot analysis demonstrated that Grap-2 has two major transcripts of 1.4 and 4.0 kb that can only be detected in tissues rich in leukocytes and in two leukemia cell lines. This highly restricted pattern of expression suggests that Grap-2 may participate in leukocyte-specific protein tyrosine kinase signaling.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Three novel proteins of the syntaxin/SNAP-25 family.

Intracellular membrane traffic is thought to be regulated in part by soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (SNAREs) through the formation of complexes between these proteins present on vesicle and target membranes. All known SNARE-mediated fusion events involve members of the syntaxin and vesicle-associated membrane protein families. The diversity of mammalian membrane compartments predicts the existence of a large number of different syntaxin and vesicle-associated membrane protein genes. To further investigate the spectrum of SNAREs and their roles in membrane trafficking we characterized three novel members of the syntaxin and SNAP-25 (synaptosome-associated protein of 25 kDa) subfamilies. The proteins are broadly expressed, suggesting a general role in vesicle trafficking, and localize to distinct membrane compartments. Syntaxin 8 co-localizes with markers of the endoplasmic reticulum. Syntaxin 17, a divergent member of the syntaxin family, partially overlaps with endoplasmic reticulum markers, and SNAP-29 is broadly localized on multiple membranes. SNAP-29 does not contain a predicted membrane anchor characteristic of other SNAREs. In vitro studies established that SNAP-29 is capable of binding to a broad range of syntaxins.

Amino Acid Sequence↗
PubMed1998

Mapping, genomic organization and promoter analysis of the human prostate-specific membrane antigen gene.

Prostate-specific membrane antigen (PSMA) is a 100 kDa type II transmembrane protein with folate hydrolase and NAALAdase activity. PSMA is highly expressed in prostate cancer and the vasculature of most solid tumors, and is currently the target of a number of diagnostic and therapeutic strategies. PSMA is also expressed in the brain, and is involved in conversion of the major neurotransmitter NAAG (N-acetyl-aspartyl glutamate) to NAA and free glutamate, the levels of which are disrupted in several neurological disorders including multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's disease and schizophrenia. To facilitate analysis of the role of PSMA in carcinoma we have determined the structural organization of the gene. The gene consists of 19 exons spanning approximately 60 kb of genomic DNA. A 1244 nt portion of the 5' region of the PSMA gene was able to drive the firefly luciferase reporter gene in prostate but not breast-derived cell lines. We have mapped the gene encoding PSMA to 11p11-p12, however a gene homologous, but not identical, to PSMA exists on chromosome 11q14. Analysis of sequence differences between non-coding regions of the two genes suggests duplication and divergence occurred 22 million years ago.

Antigens, Surface↗
PubMed1998

The glycine box: a determinant of specificity for fibroblast growth factor.

Acidic fibroblast growth factor (FGF-1), keratinocyte growth factor (FGF-7), and FGF-10 are homologues with distinct specificity. In the presence of heparin, FGF-1 binds and activates in vitro all FGFR subtypes, while FGF-7 exhibits absolute specificity for the IIIb splice variant of FGFR2. FGF-10 exhibits a similar specificity but also binds the FGFR1IIIb isoform. Neither FGF-7 nor FGF-10 will bind to IIIc isoforms of FGFR. Molecular models of FGF, heparin, and the FGFR ectodomain suggested that sequences between beta-strands 10 and 12 of FGF may be important for the interaction of FGF with the heparin-FGFR ectodomain duplex. Site-directed mutants of FGF-7 and FGF-10 were prepared to test whether this domain might underlie failure of FGF-7 and FGF-10 to bind to the FGFRIIIc isoforms. Constructions with substitution of FGF-1 sequences spanning the entire C-terminus encoded in exon 3 or only C-terminal sequences spanning beta-strands 10 through 12 conferred ability on FGF-7 to bind to and activate FGFRIIIc without a significant loss in binding to or activation of FGFR2IIIb. A series of twelve different substitutions of shorter segments of FGF-1 sequences into the C-terminal portion of FGF-7 or FGF-10 revealed that substitution of GSCKRG for GIPVRG or the tri-peptide sequence KKN for NQK just N-terminal to it conferred dual activities on both the FGF-7 and FGF-10 backbones. The results suggest that the combined sequence domain, which we call the FGF glycine box (G-box), is a major determinant for the specificity of the binding of FGF to heparan sulfate-FGFR duplexes.

Amino Acid Sequence↗
PubMed1998

Evidence that tumor necrosis factor alpha converting enzyme is involved in regulated alpha-secretase cleavage of the Alzheimer amyloid protein precursor.

The amyloid protein, Abeta, which accumulates in the brains of Alzheimer patients, is derived by proteolysis of the amyloid protein precursor (APP). APP can undergo endoproteolytic processing at three sites, one at the amino terminus of the Abeta domain (beta-cleavage), one within the Abeta domain (alpha-cleavage), and one at the carboxyl terminus of the Abeta domain (gamma-cleavage). The enzymes responsible for these activities have not been unambiguously identified. By the use of gene disruption (knockout), we now demonstrate that TACE (tumor necrosis factor alpha converting enzyme), a member of the ADAM family (a disintegrin and metalloprotease-family) of proteases, plays a central role in regulated alpha-cleavage of APP. Our data suggest that TACE may be the alpha-secretase responsible for the majority of regulated alpha-cleavage in cultured cells. Furthermore, we show that inhibiting this enzyme affects both APP secretion and Abeta formation in cultured cells.

ADAM Proteins↗
PubMed1998

Proton resonance assignments and ligand exchange kinetics in high-spin and mixed-spin myoglobin complexes using two-dimensional exchange spectroscopy.

The task of assigning resonances in proton nuclear magnetic resonance spectra of paramagnetic heme proteins can be an arduous process, but with the development of multi-dimensional NMR methods the situation has improved. It is demonstrated here that two-dimensional exchange spectroscopic experiments can be used to obtain to assignment correlations for the heme protons of methydroxy-, metthiocyano-, metaquo-, and metimidazole-myoglobin forms. All the assignments are unambiguous and straightforward when the temperature and mixing times are adjusted to minimize nuclear Overhauser cross-peaks from each complex. Moreover, saturation transfer experiments allow the study of ligand binding kinetics. The exchange rates between metaquo- and metimidazole- (or methyl substituted imidazole) myoglobin complexes are estimated. The differences between the exchange rates reflect differences in the hydrophobic and steric interactions between the ligands and the protein moiety.

Animals↗
PubMed1998

Quantification of penicillin-G and procaine in equine urine and plasma using high-performance liquid chromatography.

A rapid and sensitive method for the extraction and quantification of penicillin-G and procaine in horse urine and plasma samples has been successfully developed. The method involves the use of solid-phase extraction (SPE) for penicillin-G, liquid-liquid extraction (LLE) for procaine, and high-performance liquid chromatography (HPLC) for the quantification of penicillin-G and procaine. The new method described here has been successfully applied in the pharmacokinetic studies of procaine, penicillin-G and procaine-penicillin-G administrations in the horse.

Animals↗
PubMed1998

OCA-B integrates B cell antigen receptor-, CD40L- and IL 4-mediated signals for the germinal center pathway of B cell development.

Many of the key decisions in lymphocyte differentiation and activation are dependent on integration of antigen receptor and co-receptor signals. Although there is significant understanding of these receptors and their signaling pathways, little is known about the molecular requirements for signal integration at the level of activation of gene expression. Here we show that in primary B cells, expression of the B-cell specific transcription coactivator OCA-B (also known as OBF-1 or Bob-1) is regulated synergistically by the B-cell antigen receptor, CD40L and interleukin signaling pathways. Consistent with the requirement for multiple T cell-dependent signals to induce OCA-B, we find that OCA-B protein is highly expressed in germinal center B cells. Accordingly, germinal center formation is blocked completely in the absence of OCA-B expression in B cells, whereas the helper functions of OCA-B-deficient T cells are indistinguishable from controls. The requirement for OCA-B expression in B cells is germinal center specific since the development of primary B cell follicles, the marginal zone and plasma cells are all intact. Thus, OCA-B is the first example of a transcriptional coactivator that is both synergistically induced by and required for integration of signals that mediate cell fate decisions.

Adoptive Transfer↗