Search PubMed⌕ Search

Biomedical subjects

Q Yu

Publications and source records attributed to Q Yu.

At least 163 records · Page 9Linked to original sources
PubMed1998

[Initial evaluation of mass lesions in the head and neck with enhanced (Gd-DTPA) MR imaging].

OBJECTIVE: To evaluate mass lesions of the head and neck with enhanced (Gd-DTPA) MR imaging. METHODS: Twenty-five of patients (13 males and 12 females; mean: 46.9 years) suffered from mass lesions of the head and neck inspected with Gd-DTPA MR imaging, 17 cases were certificated histopathologically and followed up. The examinations of all patients were carried out with plain T1-weighted spin-echo sequences (TR/TE = 500-600/30), and Gd-DTPA enhanced T1-weighted spin-echo sequences (TR/TE = 300-500/30). RESULTS: Comparing with plain MR imaging, 23 mass lesions were stained on SE T1-weighted images (23/25) after intravenous administration of Gd-DTPA. The enhanced patterns of these lesions might be divided into homogeneous (10/23) and inhomogeneous (13/23). Gd-DTPA was helpful in delineating extent of 16 mass lesions. CONCLUSION: The various morphologic manifestations of enhanced lesions have close relations with their own intimate structures. The enhanced MR imaging is superior to plain MR imaging on displaying the inner structure and extent of diseases and estimating the recurrent lesions.

Adolescent↗
PubMed1998

[Six year follow-up of suspects of primary angle-closure glaucoma].

OBJECTIVE: To understand the natural history and the risk factors of primary angleclosure glaucoma and obtain experiences that might help screening for the disease. METHODS: Four hundred and eighty-five suspects were screened from 6 548 population aged over 40 years. The suspects were then followed up within six years. The following examinations were performed: visual acuity, axial anterior chamber depth, peripheral anterior chamber depth, intraocular pressure and cup/disc ratio of optic nerve papilla. The suspects with high risk were further examined. RESULTS: During the follow-up period, twenty patients (4.1%) in the suspects developed angle-closure glaucoma, 14 cases had natural attack (Acute onset developed in 6 cases and 8 cases were in chronic stage) and 6 cases were found at early stage. The anterior chamber depth shallowed progressively in 28% of suspects. CONCLUSION: Anterior chamber depth is an important index for screening of primary angle-closure glaucoma, and the regular follow-up is of significance for the suspects.

Anterior Chamber↗
PubMed1998

[The survey of anterior chamber angle in a population of middle and old age].

OBJECTIVE: To determine the condition of anterior chamber angle in a population of middle and old age, and afford data for screening of angle closure glaucoma. METHODS: Two hundred people aged 50 years or older were selected by random sampling in four districts of Doumen county. The anterior chamber angle of all people was evaluated by Goldmann one-mirror gonioscope, and the angle was graded according to the Spaeth and Shaffer's grading system. RESULTS: Three hundred ninety eyes were examined, 12% (inferior angle) to 30% (superior angle) were Shaffer's grade <or= 2. 11.3% (inferior) to 26.4% (superior) were anterior bowing of the peripheral portion of the iris, 27.7% (inferior) to 42.6% (superior) were iris insertion into seleral spur. The three aspects of the angle had significant differences in sex and age. CONCLUSION: The survey shows that the percentage of people with occludable angles increases significantly with age, and women with occludable angles are more than men. This result is important for us to make screening strategy of primary angle-closure glaucoma.

Adult↗
PubMed1998

[Studies on QSAR of the antibacterial agents quinolones: changing the parent nucleus influenced the activity].

By the method of AM1, quantum chemistry indexes of 16 compounds of quinoline, 1,8-naphthyridine and pyrido(2,3-C)pyridazine analogues were calculated and 4 QSAR equations were obtained. The results showed that the net charge of 4-carbonyl oxygen is highly correlated with the antibacterial activity in vitro, the correlation coefficient of the regressions are high(R > or = 0.96). The antibacterial activity in vitro is strongly influenced by the coplanarity of 3-carboxylic acid and the parent nucleus. In light of this study, a new parent nucleus of isothiazoleannexed quinolizine was proposed, which is expected to have much higher activity.

Bacteria↗
PubMed1997

Induction of apoptosis of metastatic mammary carcinoma cells in vivo by disruption of tumor cell surface CD44 function.

To understand how the hyaluronan receptor CD44 regulates tumor metastasis, the murine mammary carcinoma TA3/St, which constitutively expresses cell surface CD44, was transfected with cDNAs encoding soluble isoforms of CD44 and the transfectants (TA3sCD44) were compared with parental cells (transfected with expression vector only) for growth in vivo and in vitro. Local release of soluble CD44 by the transfectants inhibited the ability of endogenous cell surface CD44 to bind and internalize hyaluronan and to mediate TA3 cell invasion of hyaluronan-producing cell monolayers. Mice intravenously injected with parental TA3/St cells developed massive pulmonary metastases within 21-28 d, whereas animals injected with TA3sCD44 cells developed few or no tumors. Tracing of labeled parental and transfectant tumor cells revealed that both cell types initially adhered to pulmonary endothelium and penetrated the interstitial stroma. However, although parental cells were dividing and forming clusters within lung tissue 48 h following injection, >80% of TA3sCD44 cells underwent apoptosis. Although sCD44 transfectants displayed a marked reduction in their ability to internalize and degrade hyaluronan, they elicited abundant local hyaluronan production within invaded lung tissue, comparable to that induced by parental cells. These observations provide direct evidence that cell surface CD44 function promotes tumor cell survival in invaded tissue and that its suppression can induce apoptosis of the invading tumor cells, possibly as a result of impairing their ability to penetrate the host tissue hyaluronan barrier.

Animals↗
PubMed1997

Avoiding interferences from Good's buffers: A contiguous series of noncomplexing tertiary amine buffers covering the entire range of pH 3-11.

Of the 20 well-known buffers proposed by Good, all but 3 form metal ion complexes which can result in serious interferences, particularly in protein analyses. The structural features responsible for such complex formation have been identified. Based on a mechanistic analysis of the metal complexation process, it is proposed that tertiary amine compounds, having N-substituents which are ethyl or larger, are sterically inaccessible for initial bond formation with solvated metal ions in aqueous solution. Thus, in the absence of donor atoms on the alpha-, beta-, or gamma-carbons, metal complexation cannot proceed. The proposed noncomplexing compounds include Good's 3 noncomplexing buffers (Mes, Mops, Pipes) plus six related species. Mixed-mode acid dissociation constants (hydrogen ion in terms of activity, conjugate acid-base species in molar concentrations) have been determined for all compounds in their protonated form at 25 degrees C, mu = 0.10 M (NaNO3). The values for four compounds in this series are reported here for the first time: viz., N,N'-diethylpiperazine for which log Ka1m = 4.67 +/- 0. 03 and log Ka2m = 8.83 +/- 0.02; N,N,N',N'-tetraethylmethylenediamine for which log Ka1m < 1 and log Ka2m = 11.01 +/- 0.03; N,N'-diethyl-N,N'-bis(3-sulfopropyl)ethylenediamine for which log Ka1m = 5.75 +/- 0.03 and log Ka2m = 9.37 +/- 0.02; and piperazine-N,N'-bis(2-ethanesulfonic acid) (Pipes) for which log Ka1m = 2.81 +/- 0.01 (the value of log Ka2m having been previously reported).

Amines↗
PubMed1997

Two COOH-terminal truncated cytoplasmic forms of topoisomerase II alpha in a VP-16-selected lung cancer cell line result from partial gene deletion and alternative splicing.

Topoisomerase II alpha is a nuclear enzyme involved in chromosome segregation and other essential cellular processes. It is also the target of several clinically important antineoplastic agents such as the epipodophyllotoxin, VP-16 (etoposide). We have previously described a VP-16-selected lung cancer cell line, H209/V6, that expresses reduced levels of two species of topoisomerase II alpha-related mRNAs and a catalytically active, predominantly cytoplasmic topoisomerase II alpha-related protein that is 10 kDa smaller than the wild-type protein [Mirski, S. E. L., et al. (1993) Cancer Res. 53, 4866-4873; Feldhoff, P. W. et al. (1994) Cancer Res. 54, 756-762]. The smaller H209/V6 4.8 kb mRNA is missing 988 nucleotides of contiguous coding and non-coding sequence at its 3' end resulting in an mRNA predicted to encode a truncated polypeptide missing three previously unrecognized potential COOH-proximal bipartite nuclear localization signals [Mirski, S. E. L., & Cole, S. P. C. (1995) Cancer Res. 55, 2129-2134]. We have now determined the structure of the larger 6.2 kb topoisomerase II alpha-related mRNA and show that it is missing 684 nucleotides of contiguous 3' coding and non-coding sequence between nucleotide positions 4267 and 4951. This sequence is replaced by 847 nucleotides of new sequence, containing an in-frame stop codon after 41 nucleotides. The translation product of the 6.2 kb mRNA is predicted to contain 13 new amino acids replacing the COOH-terminal 109 residues of wild-type topoisomerase II alpha, producing a truncated polypeptide of approximately 160 kDa. Immunoblot analyses using antisera against the unique COOH-terminal 13 and 34 amino acids encoded by H209/V6 6.2 kb and 4.8 kb mRNAs, respectively, confirmed that both mRNAs are translated. Restriction enzyme analysis and sequencing of the 3'-proximal region of the TOP2A gene in the H209 and H209/V6 DNA revealed that a partial deletion has occurred in H209/V6 and the novel sequence identified in the H209/V6 6.2 kb mRNA is derived from the adjacent 3' intron as a consequence of read-through at a concensus splice donor site. These observations suggest a mechanism for the generation of the two mutant topoisomerase II alpha mRNAs in H209/V6 cells and provide the first reported example of a drug resistant cell line containing two different cytoplasmic forms of topoisomerase II alpha.

Amino Acid Sequence↗
PubMed1997

Common pattern of CD44 isoforms is expressed in morphogenetically active epithelia.

CD44 is a widely distributed cell surface glycoprotein that is expressed as many isoforms arising from a single gene by alternative splicing. An important ligand for the widespread CD44 isoform, CD44s (standard form of CD44), is hyaluronan but ligands for the numerous variant isoforms are not as well characterized. Although it has been documented that CD44 is present at critical sites and stages of morphogenesis of several organs, the nature of the isoforms expressed and their precise localization have not been described. In this study we have determined the identity and distribution of CD44 isoforms expressed during development of several embryonic mouse organs by a combination of immunohistochemistry, in situ hybridization, reverse transcription-polymerase chain reaction, and DNA sequencing. As expected from previous studies, numerous CD44 variants are expressed by actively proliferating and invaginating epithelia at sites of epithelial-mesenchymal interaction, e.g., in the developing tooth, nose and hair follicle. Our results show that most prominent amongst these variants at these sites are CD44(v3-v10), CD44(v4-v10), and CD44(v6-v10), as was also found previously in the apical ectodermal ridge of the developing limb (Yu et al. [1996]). The common pattern of expression of these three particular variants in active epithelia implies that they play an important role in morphogenesis. Also very prominent in morphogenetically active epithelia is CD44s; hyaluronan is uniformly absent from these epithelia and often also from associated mesenchyme with which they interact, supporting the previously documented role of CD44s in endocytic removal of hyaluronan.

Animals↗
PubMed1997

Internal lethal concentrations of halobenzenes with fish (Gambusia affinis).

The internal lethal concentrations is a potential measure of toxicity which could be usefully applied in environmental toxicology and risk assessment. Using halobenzenes, which are common environmental contaminants, and represented test compounds, experiments were conducted in aquaria with the mosquitofish (Gambusia affinis). The average internal lethal concentration (ILC50) for four representative halohydrocarbons, 1,4-diBB, 1,2,3-triCB, 1,2,4-triBB, and pentaCB, were consistent with those previously observed, i.e., 2.3-8.3 mmol kg-1 fish over exposure time periods of 10.4 to 633 hr. However, the ILC50 for all the compounds is not constant but decreases with increasing exposure time period with a mean first-order rate constant of (4.21 +/- 0.70) x 10-3 hr-1. The time dependency of the ILC50 is inconsistent with the critical internal concentration hypothesis which requires the ILC50 to reach a constant critical value when lethality occurs. The life expectancy of the fish from the beginning of chemical exposure could possibly be related to the ILC50-exposure time relationship.

Animals↗
PubMed1997

Modulation and detection of IDDM by membrane associated antigens from the islet beta cell line NIT-1.

We have utilized the NOD islet beta-cell line NIT-1 to monitor beta-cell specific autoantibodies and to investigate the modulation of IDDM in NOD mice by NIT-1 membrane associated antigens. The sera from diabetic but not from pre-diabetic or protected NOD mice strongly stained NIT-1 cells in FACS analysis. The cell surface antigens on NIT-1 cells were trypsin-sensitive. NIT-1 cells could not be stained by anti-mouse GAD67 antibody; however, we could demonstrate the presence of GAD65 and GAD67 mRNA by RT-PCR. Longitudinal analysis of anti-NIT-1 antibodies showed that these antibodies were present in the neonates but disappeared after weaning. Sonicated NIT-1 cell membrane preparations protected NOD mice from diabetes when injected intravenously in 5 week old mice. The protection was associated with reduced cytotoxic activity and elevated Th2-like responses as indicated by IgG1 antibodies against the NIT-1 cells. Subcutaneous injection of sonicated NIT-1 membranes or the injection of control red blood cell membranes failed to induce protection. We conclude that NIT-1 cell membranes do not express GAD but contain other antigens that are important in the development and prevention of IDDM. These antigens could be useful for the diagnosis of diabetes by monitoring autoantibody levels and for the modulation of IDDM by immunotherapy.

Animals↗
PubMed1997

Comparing estimates of the effects of air pollution on human mortality obtained using different regression methodologies.

Studies using regression techniques report their results using a variety of statistics. Evaluation of the consistency of findings, such as in a metaanalysis, requires calculating the statistical estimates of the effect reported in each study in a comparable manner. In this paper, we consider multiple linear regression, multiple Poisson regression, and logistic regression estimates. We present results that are needed to calculate, on a common basis, the slope of the regression function at a specified value, the elasticity function of the regression function at a specified value, the relative risk at a specified value, and the odds ratio at a specified value. We apply these results to studies of the association of daily mortality in an area to the daily air pollution level of ozone and PM10. We calculate the estimated slope of the number of deaths per billion population associated with an increase of 1 ppb of ozone level in studies of daily mortality in three urban areas. These studies, in Los Angeles, New York, and St. Louis, produced very comparable results on a common basis, especially when compared to the coefficients as reported. We also calculated the estimated elasticity function of the daily mortality and daily PM10 level for eight areas and found that the elasticities varied within a factor of roughly two, much less than the variability in the coefficients as reported.

Air Pollutants↗
PubMed1997

[Dissociation and morphological observation of hair cells from chick basila papilla].

Hair cells were dissociated from basila papilla of 7 to 10 week post-hatched chicks (n = 15) by collagenase digestion followed by trituration. Morphological measurements of 215 viable hair cells from 5 chicks were performed. The average dimensions of the cells were: length 20.22 +/- 3.32 microns, width 9.93 +/- 2.01 microns of tall hair cells (n = 164); length 10.97 +/- 2.29 microns, width 14.8 +/- 2.29 microns of short hair cells (n = 30); length = width = 11.93 +/- 1.74 microns of intermediate hair cells (n = 21). Using fluorescein diacetate and propidium iodide, viability of isolated hair cells from another 5 chicks was determined. With excitatory light, fluorescence of viable cells were bright green in 3 hours, while the fluorescence of live cells were attenuated to such an extent that light green shadows were showed up to 5 hours after chicks were decapitated. The results suggested that the criterion of morphological observation and dying of cells should be combined to determine viability of isolated hair cells.

Animals↗
PubMed1997

[Effect of fermented morel liquid on immunity function in mice].

The experiments studied the effect of fermented morel liquid on immunity function in mice [correction of rats]. The results showed that fermented morel liquid could greatly enhance the non-specific immunity (macrophage's phagocytosis), specific immunity (delayed-type hypersensitivity), humoral immunity (the amount of hemolysin) and the weights of thymus. The author concluded that the fermented morel liquid could effectively regulate the immunity function in mice [correction of rats].

Adjuvants, Immunologic↗
PubMed1997

[Evaluation on the method to test the sex-improve function and its key points].

The mating-test with normal mouse is one of the methods built to test wheather the type of sexual function improvement food could improve the sexual function. Through controlling the influence factor of the experiment such as the most suitabke mating time, the weights of mating mice, the mating temperature and the mating cage, and through making the female mice in different sexual response circle to be in the same, we got quite good results. The authors' study affirms the availability and dependability of the sexual function experiment method set by the authors' intitute.

Animals↗
PubMed1997

[The development of a scale of life quality for diseases with visual impairment].

OBJECTIVE: To describe the development of a scale of life (QOL) quality which measures the quality of life of Chinese patients with visual impairment. METHODS: 20 items were chosen to form a scale. 57 cataractous patients with visual impairment and 60 glaucomatous patients with visual impairment and visual field loss at different levels simultaneously were measured by the scale to evaluate the validity, reliability and responsiveness of the scale. RESULTS: The scale consists of 20 items which cover four domains of QOL. The criterion related to the validity of the scale: r = 0.6865 (P = 0.000). The test-retest reliability of the scale: r = 0.8959 (P = 0.000). Coronback's alpha was 0.9358. The variance ratio (VR) of intra-individual variance to inter-individual variance was 0.0551 for overall scores. This correlation coefficient of split-half method was 0.9553. The responsiveness: t-test, t = 5.95 (P = 0.000). The effect size statistic was 1.533. CONCLUSION: The results also demonstrate that the scale has a satisfactory validity, reliability and responsiveness. It is suggested that the scale can be applied in clinical trails.

Cataract↗
PubMed1997

[CT examination and diagnosis of oral and maxillofacial tumors invading the pterygopalatine space].

CT findings in 33 cases (proven histopathologically) suffered from oral and maxillofacial tumors affecting the pterygopalatine space were retrospectively analyzed. The authors conclude that the main CT manifestations of this space involvement by tumors can be depicted as a soft tissue mass occupancy and the wall structures destruction. Tumors occurring in different locations of oral and maxillofacial areas have different features of CT appearances. In addition, the primary tumor of this space is probed from histogenesis and CT findings, and its diagnostic criteria are discussed. As a modality of imaging, CT has an important role for assessing the lesions of this fossa.

Adolescent↗