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Q Yu

Publications and source records attributed to Q Yu.

At least 199 records · Page 11Linked to original sources
PubMed1996

Expression of multiple CD44 isoforms in the apical ectodermal ridge of the embryonic mouse limb.

Previous immunohistochemical studies have shown that CD44 is highly enriched within the apical ectodermal ridge of the developing limb (Wheatley et al. [1993] Development 119: 295-306), but the particular isoforms of CD44 were not identified. We show here that CD44s (standard or "hemopoietic" isoform) and several CD44 variants, especially V3-V10, V4-V10, and V6-V10, are concentrated in the apical ectodermal ridge in the early mouse limb. Since CD44s is a major cell surface receptor for hyaluronan, we compared its localization with that of hyaluronan. In the early limb bud, hyaluronan is distributed throughout the mesoderm but is absent from all regions of the ectoderm. Hyaluronan is especially enriched in the basement membrane separating ectoderm and mesoderm, except beneath the apical ectodermal ridge where it is absent. Since CD44s is a known endocytic receptor for hyaluronan, its presence in ridge ectoderm could lead to degradation of hyaluronan destined for the neighboring region of basement membrane, thus facilitating interaction of the ridge with underlying mesoderm. The CD44 (V3-V10) isoform found in the ridge is expressed elsewhere as a proteoglycan with heparan sulfate chains that bind fibroblast growth factors. Since fibroblast growth factors are present in the ridge and are essential for limb morphogenesis, CD44 (V3-V10) is likely to act as a cofactor or modulator in the growth-promoting action or maintenance of the ridge.

Animals↗
PubMed1996

Elastic area compressibility of the rabbit aorta.

In this paper, we apply the micropipette to reduce the surface area of the rabbit aorta, and the relationship between the fractional area change of the aortic surface and the negative pressure in the pipette is studied. The experimental results for seven rabbit thoracic aortas show that the relationship can be expressed as P = K x (ec alpha- 1), where P is the negative pressure applied to the aorta surface through the micropipette, alpha is the fractional area change of the aortic surface, K and C are constants. For the rabbit thoracic aorta, the value of K is between 5 and 17 kPa, with a mean of 8.66 kPa the value of C is between 8 and 19, with a mean of 12.11.

Animals↗
PubMed1996

Peptide analogs with different affinites for MHC alter the cytokine profile of T helper cells.

The interaction of the TCR with the immunogenic peptide bound to MHC class II molecules leads to the activation of the CD4(+) T helper cells. T helper cells have been divided into two subsets, Th1 and Th2, on the basis of the cytokines secreted by them. Th1 cells which secrete IL-2, IFN-gamma and tumor necrosis factor-beta induce delayed-type hypersensitivity, while Th2 cells secreting IL-4, IL-5, IL-6 and IL-10 induce humoral immune response. However, the mechanism of selective activation of Th1 and Th2 cells in response to different antigens is not fully understood. In this study we examined the selective activation of Th1 and Th2 cells in response to strongly immunogenic synthetic peptides EYK(EYA)3, abbreviated as K3; EYK(EYA)4, abbreviated as K4; and EYKEYAAYA(EYA)2, abbreviated as K1A2. These peptides are recognized by H-2(d) T cells in the context of I-Ad, and are strongly cross-reactive in both T cell response and antibody response. The peptide K1A2 has very high affinity for I-Ad while K3 has a much lower affinity. K4 has affinity intermediate between K1A2 and K3. The peptide K1A2 induced Th1 and K3 induced Th2 cells in BALB/c mice as suggested by their cytokine profiles. K4 induced both Th1- and Th2-type cytokines. This was also confirmed by the analysis of both IgG1 and IgG2a responses in vivo. There was a shift toward a Th1-type cytokine profile when K3-primed T cells were challenged with K1A2 in vitro but K1A2-primed cells did not show any shift when challenged with K3. Immunization with higher doses of K3 shifted the response towards Th1 type, while immunization with lower doses of K1A2 did not shift the response toward Th2. We conclude that cells primed with high-affinity peptide are committed to differentiate into Th1 irrespective of the priming dose and affinity of challenge antigen. On the other hand, the differentiation of cells primed with low-affinity peptide depends upon the dose of immunization and binding affinity of the challenge antigen for MHC.

Amino Acid Sequence↗
PubMed1996

The zinc finger of nucleocapsid protein of Friend murine leukemia virus is critical for proviral DNA synthesis in vivo.

Nucleocapsid protein NCp10 of murine leukemia virus (MuLV) is encoded by the 3' domain of gag and contains a zinc finger of the form Cys-X2-Cys-X4-His-X4-Cys flanked by basic amino acids. In the course of virus assembly, NCp10 is necessary for core formation, and the zinc finger flanked by the basic residues is required for the packaging of the genomic RNA dimer. In vitro, NCp10 exhibits strong nucleic acid binding and annealing activities that appear to be critical for virus infectivity since NCp10 promotes dimerization of the viral RNA containing the E/DLS packaging-dimerization signal and annealing of replication primer tRNA(Pro) to the initiation site of reverse transcription (PBS). Recent in vitro studies have suggested that NCp10 may also play a role in proviral DNA synthesis. To investigate the function of NCp10 in proviral DNA synthesis in vivo, we developed a simple and convenient genetic packaging system consisting of two DNA constructs expressing the packaging components gag-pol and env of Friend MuLV and a Moloney MuLV-based lacZ vector with either the MuLV E+ or a rat VL30 E packaging signal. This system allowed us to examine the consequences of a set of mutations in NCp10 on a single round of recombinant virus replication. Most mutations in the N- or C-terminal domain of NCp10 do not significantly alter infectivity, while those in the zinc finger drastically impair infectivity. Analysis of the viral RNA content in virions showed that all mutations in the zinc finger decrease but do not abolish packaging of the recombinant genome. Interestingly enough, mutation of Y-28 to S (mutation Y28S) in the zinc finger results in RNA packaging at a level similar to that observed upon deletion of three prolines and three arginines in the C-terminal domain of NCp10 (mutant delta PR3). However, mutant Y28S is noninfectious while mutant delta PR3 is only threefold less infectious than the wild-type virus, which prompted us to examine the role of NCp10 protein in proviral DNA synthesis in vivo using these nucleocapsid mutants. PCR amplification was used to analyze viral DNA synthesized in newly infected cells, and results indicate that the Y28S zinc finger mutation impairs reverse transcription, thus suggesting that the nucleocapsid protein zinc finger plays a key role in proviral DNA synthesis in vivo.

3T3 Cells↗
PubMed1996

Type I receptor serine-threonine kinase preferentially expressed in pulmonary blood vessels.

Type II and type I receptor serine-threonine kinases (RSTK) are important components of the transmembrane signaling machinery that allow cells to respond to the transforming growth factor-beta (TGF-beta) superfamily of cytokines. We have cloned from rat lung and report here a 3,935-base pair (bp) cDNA encoding a type I RSTK previously identified as R-3 (rat) or ALK-1 (human). Northern blot analysis reveals that the R-3 mRNA is more abundant in lung than in other adult rat tissues. With the use of in situ hybridization, the R-3 transcripts are found exclusively in the pulmonary vessels of all sizes, as well as in aorta, vena cava, and certain blood vessels of kidney, spleen, heart and intestine. In most blood vessels, a higher level of gene expression is found in endothelium than in adjacent smooth muscle. The R-3 transcripts are also found in splenic macrophages, as well as within cells of marginal zone of the splenic lymphoid tissue. In fetal rat lung, the expression of R-3 transcripts differs from the expression patterns of two other type 1 RSTK. The R-3 is expressed in vessels; the activin type IB receptor (R-2) is preferentially expressed in putative developing airways, whereas the TGF-beta type I receptor (R-4) transcripts appear to be ubiquitous. Our data suggest that in vivo R-3 may propagate signaling of TGF-beta in selected cell types. The differential expression of multiple type I receptors within different cell lineages may therefore define cell specific responses to TGF-beta.

Aging↗
PubMed1996

High-frequency oscillations in membrane potentials of medullary inspiratory and expiratory neurons (including laryngeal motoneurons).

1. In midcollicular decerebrate, unanesthetized, paralyzed cats ventilated with a cycle-triggered pump system, the properties of high-frequency oscillations (HFOs, 50-100 Hz) in membrane potentials (MPs) of medullary inspiratory (I) and expiratory (E) cells were studied. Simultaneous recordings were taken from bilateral phrenic and recurrent laryngeal (RL) nerves and from cells in the intermediate ventral respiratory group (intVRG, 0-1 mm rostral to the obex) or the caudal ventral respiratory group (cVRG, 2-4 mm caudal to the obex). 2. Spectral coherence analyses were used to detect the presence of HFOs during I in I and E cell MPs. Cross-correlation histograms (CCHs) between the cell and phrenic signals were used to ascertain cell-nerve HFO phase relations and to identify cells as RL motoneurons. Of the 103 cells that had significant HFOs (cell-phrenic coherences > or = 0.1), measurable HFO peak lags in the CCH were seen in 53 cells: 1) RL cells (9 I cells and 7 E cells); and 2) other types of cell (8 intVRG I cells, 18 intVRG E cells, and 11 cVRG E cells). These cells had high HFO correlations; the cell-phrenic coherence range was 0.35-0.94, with a mean HFO frequency of 58 Hz. 3. The cell-phrenic HFO lag (in ms) was measured in the CCH as the lag of the primary peak (peak located nearest to 0 lag). The phase lag was defined as (lag of primary peak in ms)/(HFO period in ms). The phase lags differed markedly between two subsets of cells: 1) RL I cells had HFO depolarization peaks that lagged the phrenic HFO peaks (average cell-phrenic phase lag = -0.18); and 2) the non-RL cells, regardless of location (intVRG or cVRG) and type (I or E), had HFO depolarization peaks leading (preceding) the phrenic HFO peaks (average cell-phrenic phase lag = 0.28). In addition, the cVRG E cells had significantly shorter cell-phrenic phase lags than the intVRG E cells (0.23 vs. 0.31, respectively). 4. These lags can be compared with the (I unit)-phrenic phase lags (average approximately 0.3) found in earlier extracellular studies. 1) There is a transmission delay of about one half HFO cycle from excitatory I cells to RL I cells. 2) Because a depolarization peak in the MP of an E cell corresponds to the start of a hyperpolarizing wave, the excitatory bulbospinal pathways from I cells have transmission times comparable with those of the inhibitory intramedullary pathways from I cells to E cells. 5. These results indicate that study of HFO phase relations can furnish useful information on functional connectivity of medullary respiratory neurons during the I phase.

Animals↗
PubMed1996

A variant of beta fibrinogen is a genetic risk factor for coronary artery disease and myocardial infarction.

BACKGROUND: Coronary artery disease is a complex trait caused by a number of genetic and environmental factors. Genes involved in hemostasis and coagulation are excellent candidate genes for CAD and its thrombotic complications, i.e., myocardial infarction (MI) and unstable angina. METHODS: We determined the frequency of beta-fibrinogen genotypes in a homogenous patient population with CAD undergoing coronary angioplasty and in a comparable group in the general population. DNA was extracted from the blood and genotypes were determined by polymerase chain reaction, restriction mapping with Hha-1 and gel electrophoresis. Cases and controls were also genotyped for a G17382T polymorphism in the (beta-Myosin heavy chain) (beta-MyHC) gene, which is not a candidate gene for CAD. RESULTS: The distribution of beta-MyHC G/T genotypes and the frequency of alleles were similar in cases and controls. However, the beta-fibrinogen G/G genotype was present in 71% of patients with CAD as compared to 54% in the general population (p = 0.00001, OR: 2.1, 95% CI: 1.7-2.8). Seventy-one percent of patients with MI and 72% of patients with unstable angina had G/G genotype (p = 0.003, OR: 2.0, 95% CI: 1.3-3.3, and p = 0.005, OR: 2.1, 95% CI: 1.3-3.7, respectively). Sixty-nine percent of male and 82% of female patients with CAD had the G/G genotype as compared to 56% and 53% in in general population, respectively (p = 0.0381, and 0.0003, respectively). Multivariate regression analysis showed that the allele G was an independent predictor of case-control status or risk of MI in a codominant manner (F = 86.8 p < 0.0001). CONCLUSIONS: beta-fibrinogen G/G genotype is a genetic risk factor for predisposition to CAD and its thrombotic complications.

Adult↗
PubMed1996

Field evaluation of the QBC technique for rapid diagnosis of vivax malaria.

The QBC (quantitative buffy coat) technique was compared with that of the Giemsa-stained thick blood film (GTF) under field conditions in Junlian and Mingshan counties, Sichuan, China, for rapid diagnosis of vivax malaria. Blood samples were collected from 364 volunteer villagers, and each sample was examined with both the QBC and GTF techniques. For each GTF sample (10 microliters of blood), as many as 300 oil-immersion fields were examined; each QBC tube was inspected for up to 5 minutes. The GTF technique resulted in 86 positive blood samples and 278 negative; the QBC technique indicated 89 positive and 275 negative samples. Relative to the results obtained with GTF, the QBC technique had a sensitivity and specificity of 87.2% and 95.0%, respectively; concordance between the tests was 93.1%. The median time-to-positive diagnosis with the QBC technique (1.12 min) was 11% of that with GTF. The distribution of different developmental stages of Plasmodium vivax parasites was also examined in the centrifuged QBC tubes: all stages except schizonts could be found in the lower part of the platelet zone (the interphase between the monocyte and platelet layers), especially ring forms.

Azure Stains↗
PubMed1996

[Determination of metronidazole in serum by HPLC].

This paper report a sensitive and rapid method for the determination of metronidazole (MTZ) using theophylline as the internal standard. High performance liquid chromatograph model 344 (Beckman) with a 254 nm wavelength UV detector and YWG-C18H37 column (10 microns, 250 x 4.6 mm) was used. To the serum sample 200 microliters, 100 microliters phosphate buffer (0.8 mol/L, pH 7.5) was added, then extracted with 3 ml chloroform containing 5% isopropyl alcohol. The organic layer was removed and evaporated to dryness under an air stream in a 40 degrees C water bath. The residue was dissolved in 30 microliters mobile phase and 20 microliters injected. The mobile phase of water-methanol (73:27) was pumped at 1.0 ml/min through the column. The detector operated at 0.005 aufs. The retention times for MTZ and theophylline were 5.78 and 6.81 min respectively. Standard curve was linear in the concentration range of 0.3125 to 20 mg/L. The detection limit in serum was 0.02 mg/L. Extraction recovery was 77%-82%; method recovery 99%-102%; withinday RSD less than 3.0%; inter-day RSD less than 3.5%.

Chromatography, High Pressure Liquid↗
PubMed1996

Development of the scale of quality of life for diseases with visual impairment.

PURPOSE: To describe the development of the of scale quality of life which can measure the quality of life of Chinese patients with visual impairment. METHODS: Based on a thorough literature search and consultation with ophthalmologists and public health professionals, 20 items were selected to create a scale. Fifty-seven cataract patients with vision impairment and 60 glaucoma patients with vision impairment and visual field loss were measured by the scale to evaluate the validity, reliability and responsiveness of the scale. RESULTS: The scale covered four domains of the quality of life (QOL). The criterion related validity of the scale: r = 0.6865 (P = 0.001). The test-retest reliability of the scale: r = 0.8959 (P = 0.001). Coronback's alpha was 0.9359. The variance ratio (VR) of intra-individual variance to inter-individual variance was 0.0551 for overall scores. The correlation coefficient of split-half method was 0.9553. The responsiveness: T-test, T = 5.95 (P = 0.001), effect size statistic was 1.533. CONCLUSIONS: The result demonstrates that the scale has a satisfactory validity, reliability and responsiveness. It suggests that the scale can be applied to clinical trials.

Cataract↗
PubMed1996

A population-based study of lens opactities.

PURPOSE: Age-related lens opacity is the main cause of vision disability in elderly population all over the world. This study was designed to investigate the prevalence and incidence of lens opacity. METHODS: 1817 eyes of 932 adults over 45 years-old were sampled randomly from 4 villeges within Doumen, a county located in the south of Guangdong provience, China. The procedure of the examination was performed by ophthalmologists. The lens opacities were graded according to a standarized photo of the Lens Opacities Classification System II (LOCS-II). RESULTS: The prevalence of lens opacities in nuclear color, nuclear opacity, cortical opacity and subcapsular opacity was 16.1%, 28.6%, 30.3% and 8.7%, respectively. The frequency of all four types of opacities increased with age. The prevalence of lens opacities in four types was higher in female than that in male. CONCLUSION: The data we got are important for prevalence of lens opacities of population-based study as well as basic information for cohort study in the future.

Aged↗
PubMed1996

The etiology of vision impairment in target population.

PURPOSE: research the etiology of vision impairment in target persons over 45 years old in Doumen county, Guangdong province. METHODS: Depending on the prevalences of the blindness among the person aged over 50 years, the theoretic sample rate is 1,000/4,8733 x 100% = 2.05%. The 8 districts were divided into 3 parts according to the local economic situation and the proportion of the population in the areas. In fact, the sampling rate is 932/10055 = 88.34%. RESULTS: We found that impairment < 0.3 accounted for 10.94%. The prevalence of bilateral blindness and low vision was 1.61% and 3.22%, respectively. Both prevalences of blindness and low vision were increased with age. The leading cuase of blindness was cataract (45.2%). The second was corneal opacity (16.7%). Prevalences of the low vision and the blindness were higher in females than in males (P < 0.005). CONCLUSIONS: Curable and preventable diseases were the leading cause for the blindness (70%). Prevalences of blindness and the low vision increase with age. We will continually follow up the population over 50 years of age in Doumen county.

Age Factors↗
PubMed1996

[Evaluation for grading standard of oblique flashlight test].

PURPOSE: We try to study the validity and reliability of grading standard of oblique flashlight test in this paper. METHODS: The validity of the grading standard of the oblique flashlight test was evaluated in 251 eyes. Based on anterior chamber angle as the gold standard, different grades of oblique flashlight test can find capable of closure angle sensitivity and specificity. The reliabilities (interobserver agreement and intraobserver agreement) also were evaluated in 250 and 88 eyes. RESULTS: 1. Validity of grading standard of oblique flashlight test: the results showed that it can find capable of closure angle sensitivity is 96.67%, specificity is 74.53% and Youden's index is 0.712, when the grades cutoff point on grade II. 2. Reliability of grading standard of oblique flashlight test: the results showed that the intraobserver agreement was observed agreement (Po) = 0.8, Kappa value (K) = 0.74 , Z = 22.48 and the intraobserver agreement was Po = 0.909, K = 0.875, Z = 16.08. CONCLUSIONS: The results of this research showed there are satisfactory validity and reliability for grading standard of oblique flashlight test. The test may be applied widely to estimate shallow anterior chamber and narrow angle.

Anterior Chamber↗
PubMed1995

Determination of polyamines in serum by high-performance capillary zone electrophoresis with indirect ultraviolet detection.

A method for determining polyamines in serum by capillary zone electrophoresis (CZE) with indirect ultraviolet detection was established. The concentrations of polyamines in the sera of six healthy adults were determined and the results were in accordance with those obtained previously by high-performance liquid chromatography (HPLC). However, the CZE method is superior to HPLC in that it has high sensitivity, small sample consumption and easy sample pretreatment.

Adult↗
PubMed1995

A novel glycosaminoglycan-binding protein is the vertebrate homologue of the cell cycle control protein, Cdc37.

Using a monoclonal antibody, IVd4, that recognizes a novel group of hyaluronan-binding proteins, we have immunoscreened a cDNA library constructed from embryonic chick heart muscle mRNA. One of the cDNAs isolated from the library encodes a 29.3-kDa protein homologous to Cdc37, an essential cell cycle regulatory factor previously characterized genetically in yeast and Drosophila; this is the first vertebrate CDC37 gene to be cloned to date. We also present evidence for the existence of a second chick isoform that is identical to the 29.3-kDa protein over the first 175 amino acids but is entirely different at the carboxyl terminus and lacks the IVd4 epitope. The avian Cdc37 binds hyaluronan, chondroitin sulfate and heparin in vitro, and both isoforms contain glycosaminoglycan-binding motifs previously described in several hyaluronan-binding proteins. These findings suggest a role for glycosaminoglycans in cell division control.

Amino Acid Sequence↗
PubMed1995

Discordant regulation of transforming growth factor-beta receptors by prostaglandin E2.

The effect of PGE2 on TGF-beta receptor binding was assessed for both signaling (type I and type II) and non-signaling (type III) TGF-beta receptors. We found in cross-linking studies that PGE2 treatment (24 h) decreased binding of TGF-beta to the type I and type II receptors by approx. 50% and markedly increased binding of TGF-beta to type III receptors nearly 10-fold. Northern analyses indicated that PGE2 decreased type I receptor mRNA levels by approximately 30-50%, decreased type II receptor mRNA levels by approximately 60%, and markedly increased type III receptor mRNA levels. Coincubation with cycloheximide partially blocked the PGE2-induced inhibition of type II receptor mRNA. In contrast, cycloheximide minimally affected PGE2-induced type III receptor mRNA levels. Activation of protein kinase C by phorbol esters had no apparent effect on TGF-beta receptor mRNA levels. Our data suggest that alterations in TGF-beta receptor expression could modify the response of tissues to TGF-beta during injury.

Animals↗