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Biomedical subjects

Q Yu

Publications and source records attributed to Q Yu.

At least 217 records · Page 12Linked to original sources
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↗
PubMed1995

Two closely related receptor-type tyrosine phosphatases are differentially expressed during rat lung development.

Transmembrane protein tyrosine phosphatases (PTPases) comprise a newly identified class of receptor-like molecules. In most cases their ligands and the substrates they dephosphorylate are not known. In order to begin to explore the functions of the PTPases in cell physiology and in mammalian development, we examined the expression patterns of two closely related receptor-type tyrosine phosphatase genes, namely LAR and PTP delta, in fetal rat lung and in selected adult rat tissues. In the lung, in situ hybridization and immunohistochemistry show that the LAR mRNA and protein are expressed exclusively in the epithelium. In the early embryonic or fetal lung (day 13 to 18) LAR is expressed by all of the epithelial cells of the forming bronchial tree. This widespread pattern of expression is lost later in fetal life (day 21) as the lung matures and acquires the morphologic and biochemical features of the adult organ. LAR gene expression is then confined to two epithelial progenitor cells of the distal airways, namely the bronchiolar Clara cell and the alveolar type II cell. The LAR gene products were also found abundantly expressed in epithelial progenitor cells of adult esophagus, skin, and small intestine, all of which are continuously renewing epithelia. The rat PTP delta gene, on the other hand, is specifically expressed in the mesenchyme of the developing lung. The level of the PTP delta mRNA decreases as the lung matures. These results suggest that the two closely related receptor-type tyrosine phosphatases are differentially expressed in a tissue-specific fashion. They are expressed mostly in proliferating cells or in cells which have potential to proliferate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Sequence and in vitro expression of the phosphoprotein gene of avian pneumovirus.

The phosphoprotein (P) gene of two subgroup A strains of avian pneumovirus comprised 855 nucleotides containing only one substantial open reading frame encoding a protein of 278 amino acids, with a predicted M(r) of 30,323. In vitro translation of P mRNA in a wheat germ system resulted in the synthesis of two polypeptides of M(r) 35,000. Comparison of the deduced P protein sequence with that of the known mammalian pneumoviruses revealed overall amino acid identities ranging from 31 to 34.5%, suggesting a distant relationship. However, there was a much higher identity (63.2-68.4%) in a region of 57 residues, which included a heptad repeat sequence.

Amino Acid Sequence↗
PubMed1995

Radiographic findings in Langerhans' cell disease affecting the mandible.

The radiographic features of histopathologically diagnosed mandibular Langerhans' cell disease are described for 29 cases of the condition. We divided the patients into two groups: adults (age 27 to 60 years) and juveniles (age 1.5 to 15 years). A characteristic sign in juveniles was an osteolytic lesion with an uneven margin and either a continuous or discontinuous periosteal reaction. Because of the wide variability in radiographic presentation in adults, it was very difficult to differentiate this from other lesions in adults on the basis of radiologic criteria.

Adolescent↗
PubMed1995

Computed tomography of pulmonary metastases from oral and maxillofacial tumors.

Computed tomographic scans were done on 14 oral and maxillofacial malignant tumors in which pulmonary metastases occurred but were poorly delineated by conventional chest radiography and tomography. Computed tomography promotes the accurate diagnosis of small and occult pulmonary metastases. Optimal nonlinear computed tomographic windows are recommended for the diagnosis of pulmonary metastases.

Adult↗
PubMed1995

Functional cDNA clones of the human respiratory syncytial (RS) virus N, P, and L proteins support replication of RS virus genomic RNA analogs and define minimal trans-acting requirements for RNA replication.

The RNA-dependent RNA polymerase of human respiratory syncytial (RS) virus was expressed in a functional form from a cDNA clone. Coexpression of the viral polymerase (L) protein, phosphoprotein (P), and nucleocapsid (N) protein allowed us to develop a system for expression and recovery of replicable RS virus RNA entirely from cDNA clones. cDNA clones of the N, P, and L genes were constructed in pGEM-based expression plasmids and shown to direct expression of the appropriate polypeptides. Two types of RS virus genomic RNA analogs were expressed from an intracellular transcription plasmid that directed the synthesis of RNAs with defined 5' and 3' ends. One analog included the authentic 5' and 3' termini of the genome, and the second contained the authentic 5' terminus and its complement at the 3' terminus as found in copyback defective interfering RNAs of other negative-strand RNA viruses. Both types of genomic analogs were encapsidated and replicated in cells expressing the RS virus N, P, and L proteins. Omission of any of the three viral proteins abrogated replication, thereby defining the N, P, and L proteins as the minimal trans-acting proteins required for RNA replication. This system has the advantages that expression occurs at a level sufficient to allow direct biochemical analysis of the products of RNA replication and that neither the use of reporter genes nor wild-type RS helper virus is required. These features allow analysis of both cis- and trans-acting factors involved in the control of replication of RS virus RNA.

Cell Line↗
PubMed1995

Preferential correlations of a medullary neuron's activity to different sympathetic outflows as revealed by partial coherence analysis.

1. In vagotomized, paralyzed, decerebrate cats, simultaneous recordings were taken from one or more sympathetic nerves [cervical sympathetic (CS), inferior cardiac (IC), splanchnic (SP)] and from medullary neurons in vasomotor-related regions. Coherence analyses were used to ascertain the presence of sympathetic rhythms (2-6 Hz or "3-Hz rhythm," 7-13 Hz or "10-Hz rhythm") that were correlated between different signals. The occurrence of a significant peak at such a frequency in a unit-nerve coherence spectrum allowed the identification of a medullary neuron as sympathetic related. 2. A serendipitous example is given of a rostral ventrolateral medullary neuron that had significant unit-nerve 10-Hz coherence peaks for three sympathetic nerves (CS, IC, SP); but, as revealed by partial coherence analysis, the unit activity's correlation with one nerve's activity could be partially or completely dependent on its correlation with other nerve activities. Thus in this case the unit-CS and unit-IC coherences at 10 Hz were completely dependent on the SP rhythm, whereas the unit-SP coherence was not significantly affected by the CS and IC rhythms. This asymmetry suggests that the neuron was preferentially connected to SP-generating medullary circuits. 3. This example indicates the strength of partial coherence analysis as a means of studying differential connectivity between medullary sympathetic-related neurons and sympathetic output neuron populations.

Animals↗
PubMed1995

[An epidemiological survey of primary angle-closure glaucoma in Doumen county Guangdong].

A comparison between the results of an epidemiological study of primary angle-closure glaucoma (PACG) in Doumen County, Guangdong in 1990 and those of a similar study in Shunyi County, Beijing in 1985 was reported. The prevalence of PACG in subjects over 45 years old was 0.64% and that, over 50 years, 0.85% in Doumen, while that, over 50 years, 1.99% in Shunyi (P < 0.05). There was significant difference in the prevalence of PACG between the two counties and the difference was discussed.

Aged↗
PubMed1995

Epidemiological survey of primary angle-closure glaucoma in Doumen.

PURPOSE: To determine the prevalence of primary angle-closure glaucoma (PACG) in Doumen Countty, Guangdong province. METHODS: Four villages from eight districts in doumen were selected by stratified, cluster and random sampling. Of a total of 1055 people aged 45 years or over, 932 (88.62%) were examined. The examination and diagnostic criterion were similar to those of shunyi survey. RESULTS: The prevalence of PACG in subjects over 45 year of eye is 0.64%, in those over 50 years of age is 0.85% in Doumen, which is significantly lower than the corresponding figure of 1.99% in shunyi (P < 0.05). CONCLUSION: This study identifies the prevalence of PACG in Doumen is lower than in Shunyi.

Aged↗
PubMed1995

[Simultaneous staining with fluorescein diacetate-propidium iodide to determine isolated cochlear outer hair cell viability of guinea pig].

A simultaneous double-staining procedure using fluorescein diacetate (FDA) and propidium iodide (PI) is discribed for use in the determination of isolated cochlear outer hair cell viability. With exciter light, viable cells fluoresce bright green, while nonviable cells are bright red. In cell culture and cytotoxicity studies, double-staining with FDA-PI is a accurate method to discriminate between live and nonviable cells.

Animals↗
PubMed1995

[Effect of electrical stimulation of red nucleus on acupuncture analgesia].

The function of red nucleus (RN) was important in motor control. This work was to study whether the RN influenced the effect of EA and the somatosensory afferent system. C-responses of spinal dorsal horn neurons (SDHN) were recorded as nociceptive responses. Electrical stimulation of RN could intensify the inhibitory effect of EA and inhibit nociptive response of SDHN. Naloxone (NX) could completely block that inhibition of RN. The result inferred that the RN can modulate both of somatomotion and somatosense. The endogenous opiate system is involved in the somatosensory modulation of RN.

Acupuncture Analgesia↗
PubMed1995

[The study of grading standard photos of oblique flashlight test].

PURPOSE: We try to establish a convenient, fast, inexpensive and accurate screening test and to make a grading standard. METHODS: 1. In 120 eyes, we measured axial anterior chamber depth (AACD), peripheral anterior chamber depth (PACD), antrior chamber angle (ACA) and took iris pictures under slitlamp microscope imitating the oblique flashlight test. The clear photos from 107 eyes were measured by computerized image analysis to determin the ratio of the width of nasal iris and nasal iris light band (ILBR). Then the linear correlation of ILBR with AACD, PACD and ACA was analyzed statistically. The ILBR was graded according to the analytic results. RESULTS: 1. Relationship of ILBR with PACD, AACD and ACA: the linear correlation analysis showed a positive correlation relationship among ILBR, PACD and AACD (r = 0.9451, P = 0.0001 and r = 0.8725, P = 0.0001), and showed a negative correlation relationship between ILBR and ACA (r = -0.7582, P = 0.0001). 2. ILBR grading standards: grade 1. ILBR < or = 1/5, the gonioscopy usually demonstrates a dangerously narrowed angle (N3-4); grade 2, ILBR > 1/5- < or = 1/4, the gonioscopy will always show a capable of closure angle (N2-3); grade 3, ILBR > 1/4- < or = 1/3, that angle is incapable of closure (N1-2); grade 4, ILBR > 1/3- < or = 1/2, the most angles show wide (W-N1); grade 5, ILBR > 1/2, the gonioscopy shows all wide angle. The linear correlation analysis also showed correlation relationship among ILBR grades PACD, AACD and ACA. CONCLUSION: Through arational ILBR grades and a set of grading standard photos, it is found that the test is not only convenient, fast, and inexpensive, but also accurate as well. The test not only plays an important role in PACG screening, but also may be applied widely to estimate shallow AACD and narrow angle in the clinic.

Anterior Chamber↗
PubMed1995

[A role of oblique flashlight test in screening for primary angle closure glaucoma].

PURPOSE: To study the effect of oblique flashlight test in screening for primary angle closure glaucoma. METHOD: Two hundred adults over 50 years old were sampled randomly at Doumen county of Guangdong province in 1995. 390 eyes were measured by oblique flashlight test according to grading standard photos of oblique flashlight test. Other ocular examinations consisted of intraocular-pressure measurement with Schiotz tonometer, gonioscopy, and optic disc appearance. RESULTS: The result showed 25.2% of the examined eyes had the oblique flashlight grade < or = 2, and tended to be increasing with age (x2 = 8.597, P < 0.05) and in females (x2 = 14.89, P < 0.01). Based on temporal anterior chamber angle < or = 2 (Shaffer's grade), the obligue flashlight grade < or = 2 found that occludable angle sensitivity was 91.7%, specificity was 91.5%, and 8.16% of the eyes had primary closure angle glaucoma. No patient was found in oblique flashlight grades > or = 3. CONCLUSION: This study shows that oblique flashlight test conforms to screening test needs, and plays an important role in screening for primary closure angle glaucoma. We suggest that oblique flashlight grades < or = 2 as cutoff point of screening for occludable angle.

Aged↗
PubMed1994

Evidence from CD spectra that d(purine).r(pyrimidine) and r(purine).d(pyrimidine) hybrids are in different structural classes.

CD spectra and difference CD spectra of four d(oligopurine).r(oligopyrimidine) and four r(oligopurine).d(oligopyrimidine) hybrid duplexes containing mixed A.T(U) and G.C base pairs were compared with the spectra of four DNA.DNA and four RNA.RNA oligomer duplexes of similar repeating sequences. The 16 duplexes were formed by mixing oligomers that were 24 nucleotides long. The buffer was 0.05 M Na+ (phosphate), pH 7.0. DNA.DNA and RNA.RNA oligomer duplexes were used as reference B-form and A-form structures. We found that the CD spectra of d(purine).r(pyrimidine) and r(purine).d(pyrimidine) hybrid duplexes were different from the CD spectra of either DNA.DNA or RNA.RNA duplexes. The data suggested that these hybrids have intermediate structures between A-form RNA and B-form DNA structures. The CD spectra of d(purine).r(pyrimidine) and r(purine).d(pyrimidine) hybrid duplexes were different from each other, but the hybrids in each class had consistent CD spectra as indicated by nearest-neighbor comparisons. Thus, it appeared that the two types of hybrids belonged to different structural classes. The negative 210 nm band found in difference CD spectra was correlated with the presence of an r(purine) strand in the hybrid duplexes. The melting temperatures (Tm values) of these hybrids were compared with the Tm values of the DNA.DNA and RNA.RNA duplexes. The order of the thermal stability was: RNA.RNA duplex > r(purine).d(pyrimidine) hybrid > DNA.DNA duplex > d(purine).r(pyrimidine) hybrid, when comparing analogous sequences.

Base Composition↗
PubMed1994

On-line buffer removal and fraction selection in gradient capillary high-performance liquid chromatography prior to electrospray mass spectrometry of peptides and proteins.

The technique for on-line removal of buffers and for fraction selection to eliminate source clogging and suppression of electrospray ionization by unwanted constituents consisted of: (i) selecting the initial mobile phase composition to retain analytes on top of a capillary high-performance liquid chromatography (HPLC) column; (ii) washing the buffer isocratically to waste, using a two-way micro dump valve; (iii) starting the gradient and switching the dump valve to introduce analytes into the source. Peptide and protein mixtures were prepared in 0.05-0.5 M phosphate and 0.55 mM tris-based buffers, and water. After buffer removal, chromatograms and electrospray spectra were indistinguishable from those of aqueous controls, down to 1 pmol (acidic fibroblast growth factor) consumed, and up to 78 kDa (bovine transferrin) molecular weight. Aided by the dump valve, 100 fmol of angiotensin could be fractionated and identified on the slope of a 10 x 10(6) fmol of leucine enkephalin HPLC peak. On-line buffer removal and fraction selection eliminate the need for additional preparation steps than can lead to excessive sample losses.

Buffers↗
PubMed1994

Characterization of two density populations of feline calicivirus particles.

Feline calicivirus (FCV) F9 strain was propagated in Crandall-Reese feline kidney cells. Two density populations of viral particles were observed after equilibrium centrifugation in an isopyknic CsCl gradient. The buoyant density of the heavy particle (PH) is 1.33 g/ml. The light particle (PL), a previously undescribed form of feline calicivirus, has a buoyant density of 1.22 g/ml. The PH and PL presented a similar morphology by electron microscopy. Western blot showed that both PH and PL contained a major polypeptide of the typical FCV capsid protein with a molecular weight of 62,000. Infectivity assay and RNA isolation demonstrated that PH is the intact infectious virion while PL is FCV empty capsid.

Animals↗