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Biomedical subjects

H Yu

Publications and source records attributed to H Yu.

At least 343 records · Page 19Linked 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

[Effect of sodium ferulate on proliferation of rabbit aortic smooth muscle cells induced by oxidized LDL].

OBJECTIVE: To investigate the effect of sodium ferulate on the proliferation and lipid peroxidation of aortic smooth muscle cells(SMC). METHOD: Using experimental models of proliferation of cultured rabbit aortic SMC induced by oxidized-low density lipoprotein, the level of lipoperoxide(LPO) was determined by thiobarbituric acid reactive substance(TBARS) method and 3H-thymidine(3H-TdR) incorporation was used to observe DNA synthesis. RESULTS: SF markedly reduced the increase of medium LPO and inhibited the 3H-TdR incorporation in a dose-dependent manner. CONCLUSION: SF can inhibit the proliferation of SMC. The inhibitory effect may be related to the inhibition of lipid peroxidation.

Angelica sinensis↗
PubMed1999

[Sonographic measurement of uterine cervix in pregnancy].

The objective of this study was to evaluate the accuracy of the measurement of the cervix by comparing transvaginal sonography (TVS) with transabdominal sonography (TAS) and to assess TVS measurement of the cervix in pregnancy. The cervix was measured in the first, second, third trimesters and at term by TVS in 131 normal singleton pregnancies and by TAS in normal pregnant women. The results showed that TVS was better in providing successful rate and accurate identification of uterine cervical length, compared with TAS. The cervical lengths in the first, second, third trimesters and at term were 30.22 mm, 32.25 mm, 30.04 mm and 25.86 mm respectively. The results suggest that TVS be superior to TAS in cervical measurement and that in normal pregnancy, the cervical length does not change significantly until the time when cervical length shortening begins at term.

Adult↗
PubMed1999

[Measuring of spontaneous otoacoustic emissions of adolescence and its significance].

OBJECTIVE: In order to study the relationship between spontaneous otoacoustic emissions (SOAE) and cochlear function. METHOD: SOAE of 50 normal hearing young people were measured. The incidences, amplitudes and frequencies of SOAE were obtained. RESULT: The SOAE incidence was 40% in 100 ears of 50 cases and there was no significant difference in sexuality and laterality (P > 0.05); In the 40 cases who had SOAE, the amplitudes ranged from--27.5 dB SPL to 9.7 dB SPL and the frequencies ranged from 269 Hz to 5,660 Hz, without sexual difference; There is no significant difference between SOAE and threshold of pure tone acoustic (P > 0.05). CONCLUSION: The appearance of SOAE indicated good cochlear function.

Adult↗
PubMed1999

[Comparison of lignocellulolytic enzyme profiles secreted by Panus conchatus and Phanerochaete chrysosporium during solid state cultures].

Most of white-rot fungi, such as Phanerochaete chrysosporium, can cause severe concomitant cellulose degradation during biodegradation of lignocellulose. Panus conchatus, a white-rot fungus, can cause efficient delignification of straw with only limited concomitant cellulose degradation. The results in comparison of lignocellulolytic enzyme profiles secreted by P. conchatus and P. chrysosporium during solid state cultures have shown that laccase and Mn-dependent peroxidase are main lignin-degrading enzymes of these two fungi respectively; high activities of xylanase are secreted by both fungi; and much lower activities of cellulases i.e. endo-glucanase, avicelase and cellobiase, especially endo-glucanase, are produced by P. conchatus during the whole cultures. The results further confirm that Panus conchatus has ability of strong selective delignification of lignocellulose.

Biodegradation, Environmental↗
PubMed1999

[Progress in research of Vitreoscilla hemoglobin and Vitreoscilla hemoglobin gene].

Vitreoscilla is a Gram-negative obligate aerobic bacterium, whose most important property is the ability to produce the Vitreoscilla hemoglobin (VHb). VHb is encoded by a single gene called Vitreoscilla hemoglobin gene (vgb) containing the natural promoter, and the expression of vgb gene is regulated by dissolved oxygen at the level of transcription. The oxygen binding VHb participate in the metobolism process of cells and make them grow well in the hypoxic habitats. It also facilitates the bacteria growing and the potein producing obviously. The potential application prospect for the oxygen regulated promoter of vgb and the physiological function of VHb in the fermentation industry is reviewed.

Bacterial Proteins↗
PubMed1999

[Study on the nasal resonance].

OBJECTIVE: In order to understand the resonant function of the nasal cavity (including nasal sinuses) which is one of the resonant organs of the human body. METHOD: The maximum frequency, mean frequency and the number of harmonics of five vowels [a], [e], [i], [o], [u] were compared before and after packing of the anterior nasal cavity. RESULT: The result was analyzed statistically and showed no significant difference. CONCLUSION: It proved that the front part of the nasal cavity plays no important role in the function of the nasal resonance.

Adolescent↗
PubMed1999

[Management of thoracic esophageal perforation].

OBJECTIVE: To compare surgical management of esophageal perforation on thoracic portion with nonoperative management. METHODS: Seventeen patients were treated for thoracic esophageal perforation at our department between 1962 and 1996. Among them, seven patients underwent nonoperative management. The remaining 10 had operative procedures (primary repair in 5, esophagostomy in 3, and drainage alone in 2 cases). RESULTS: Postoperative leakage occurred in 2 patients; among the two leakages, 1 required cervical esophagostomy, and 1 became a controlled fistula needed pleural drainage and feeding jejunostomy. One patient had anastomotic narrowing after esophagostomy. Of patients with nonoperative management, five survived (with 28% in-hospital mortality rate), Whereas only one patient, who was treated by surgical procedure, died (with 10% inhospital mortality rate). The mean hospital stay in nonoperative and operative group were (28.3 +/- 12.9) days and (57.6 +/- 52.7) days respectively. CONCLUSIONS: The clinical observation suggested that rapid diagnosis of thoracic esophageal perforations is essential and once the diagnosis of esophageal perforation is established, a appropriate management must be selected promptly.

Adult↗
PubMed1999

DNA vaccination against multiple myeloma.

A variety of approaches to antitumor therapy are currently being explored that use both antigen-encoding DNA and noncoding nucleotides as a component of gene vaccination. Among the specific strategies reviewed are a construct that fuses a single-chain variable fragment (scFv) that incorporates both the variable-region genes necessary to encode the idiotypic determinants with fragment C (FrC) of tetanus toxin; a novel vector system using herpes simplex virus 1 (HSV-1) for in vivo gene delivery; the possibility of eliciting hyperacute xenograft response to treat human cancer; and the use of gene gun-mediated granulocyte-macrophage colony-stimulating factor (GM-CSF) cDNA-based tumor cell vaccines. The protection provided by DNA vaccination against viral diseases such as influenza suggested a role for such vaccines against cancer. However, unlike vaccines against infectious diseases, cancer vaccines are therapeutic, rather than prophylactic. With multiple myeloma, for example, it is possible that the optimal timing of administration of such a vaccine is during a remission that has been induced by traditional therapies, to eliminate residual disease. DNA cancer vaccines are designed to activate immune responses to tumor antigens to which the immune system has already been exposed. To do so, the vaccines must first overcome immune tolerance that may have already developed to the tumor. There is increasing evidence that tumor antigens, unlike viral or bacterial antigens, do not consistently activate an immune response. One major factor in determining whether a reaction occurs appears to be whether antigen presentation is accompanied by danger signals. With viral or bacterial infection, the accompanying tissue destruction and inflammation produce costimulatory signals that promote T-cell activation. However, inflammatory and tissue-destructive processes are absent during initial tumor transformation. The typical outcome may be immunologic tolerance.

Genetic Therapy↗
PubMed1998

Insulin-like growth factor-binding protein-3 and breast cancer survival.

Insulin-like growth factors (IGFs) are potent mitogens involved in the regulation of cell proliferation and apoptosis. The action of IGFs is mediated through a specific cell membrane receptor (IGF-IR), and the interactions between IGFs and this receptor are regulated by IGF-binding proteins (IGFBPs). IGFBP-3 is one such protein which either suppresses or enhances the actions of IGFs. Findings from most in vitro studies suggest that IGFBP-3 inhibits breast cancer cell growth and facilitates apoptosis, but clinical studies have found that high levels of IGFBP-3 in breast cancer tissues are associated with unfavourable prognostic indicators of the disease, such as large tumour size, low levels of steroid hormone receptors, elevated S-phase fraction and DNA aneuploidy. To further examine the role of IGFBP-3 in breast cancer recurrence and survival, we conducted the following nested case-control study. From a cohort of 1,000 women treated surgically for primary breast cancer, we consecutively selected 100 patients who developed recurrent disease after surgery and 100 age- and year of diagnosis-matched patients who had no relapse. Concentrations of IGFBP-3 in breast tissue extracts were determined with an ELISA. Inverse correlations of IGFBP-3 were revealed with estrogen receptor expression and patient age but not with tumour size or S-phase fraction. Levels of IGFBP-3 in breast tissues were slightly higher in the recurrent patients than in controls, but the differences were not statistically significant. No significant association was found between IGFBP-3 and breast cancer recurrence. Survival analysis, however, indicated that the risk of death was increased with higher IGFBP-3 levels, and the association was independent of other prognostic markers. In conclusion, our results demonstrate that high levels of IGFBP-3 are associated with unfavourable prognostic features of breast cancer.

Aged↗
PubMed1998

Genome scan of human systemic lupus erythematosus: evidence for linkage on chromosome 1q in African-American pedigrees.

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by production of autoantibodies against intracellular antigens including DNA, ribosomal P, Ro (SS-A), La (SS-B), and the spliceosome. Etiology is suspected to involve genetic and environmental factors. Evidence of genetic involvement includes: associations with HLA-DR3, HLA-DR2, Fcgamma receptors (FcgammaR) IIA and IIIA, and hereditary complement component deficiencies, as well as familial aggregation, monozygotic twin concordance >20%, lambdas > 10, purported linkage at 1q41-42, and inbred mouse strains that consistently develop lupus. We have completed a genome scan in 94 extended multiplex pedigrees by using model-based linkage analysis. Potential [log10 of the odds for linkage (lod) > 2.0] SLE loci have been identified at chromosomes 1q41, 1q23, and 11q14-23 in African-Americans; 14q11, 4p15, 11q25, 2q32, 19q13, 6q26-27, and 12p12-11 in European-Americans; and 1q23, 13q32, 20q13, and 1q31 in all pedigrees combined. An effect for the FcgammaRIIA candidate polymorphism) at 1q23 (lod = 3.37 in African-Americans) is syntenic with linkage in a murine model of lupus. Sib-pair and multipoint nonparametric analyses also support linkage (P < 0.05) at nine loci detected by using two-point lod score analysis (lod > 2.0). Our results are consistent with the presumed complexity of genetic susceptibility to SLE and illustrate racial origin is likely to influence the specific nature of these genetic effects.

Animals↗
PubMed1998

Natural killer cells from HIV-1+ patients produce C-C chemokines and inhibit HIV-1 infection.

Human NK cells have been shown to produce cytokines (e.g., IFN-gamma and TNF-alpha) and the chemokine macrophage inflammatory protein (MIP)-1alpha following stimulation with the combination of two monokines, IL-15 plus IL-12. The C-C chemokines MIP-1alpha, MIP-1beta, and RANTES have been identified as the major soluble macrophage-tropic HIV-1-suppressive factors produced by CD8+ T cells, which exert their action at the level of viral entry. Here, we demonstrate that monokine-activated NK cells, isolated from both normal and HIV-1+ donors, produce similar amounts of MIP-1alpha, MIP-1beta, and RANTES protein, in vitro. Further, supernatants of monokine-activated NK cells obtained from both normal donors and AIDS patients showed potent (routinely > or = 90%) suppressive activity against HIV-1 replication in vitro, compared with unstimulated control supernatants. NK cell supernatants inhibited both macrophage-tropic HIV-1(NFN-SX) and T cell-tropic HIV-1(NL4-3) replication in vitro, but not dual-tropic HIV-1(89.6). Importantly, the C-C chemokines MIP-1alpha, MIP-1beta, and RANTES were responsible only for a fraction of the HIV-1-suppressive activity exhibited by NK cell supernatants against macrophage-tropic HIV-1. Collectively these data indicate that NK cells from normal and HIV-1+ donors produce C-C chemokines and other unidentified factors that can inhibit both macrophage- and T cell-tropic HIV-1 replication in vitro. Since NK cells can be expanded in patients with HIV-1, AIDS, and AIDS malignancy in vivo, this cell type may have an important role in the in vivo regulation of HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Flt3 ligand promotes the generation of a distinct CD34(+) human natural killer cell progenitor that responds to interleukin-15.

Interleukin-15 (IL-15) is produced by human bone marrow (BM) stromal cells and can induce CD34(+) hematopoietic progenitor cells (HPCs) to differentiate into CD56(+)CD3(-) natural killer (NK) cells in the absence of stromal cells. IL-15 mediates its effects by signaling through the beta and gammac chains of the IL-2/15 receptor (R). The c-kit ligand (KL), also produced by stromal cells, enhances the expansion of NK cells from CD34(+) HPCs in the presence of IL-15, but alone has no ability to differentiate NK cells. Mice deficient in KL do not appear to have a quantitative deficiency in NK cells, suggesting that other stromal cell factors may contribute to NK cell expansion. Flt3 ligand (FL) is also produced by BM stromal cells and has homology with KL. Furthermore, mice with a targeted disruption of the FL gene have reduced numbers of NK cells. We evaluated here the effects of FL on human NK cell development and expansion from CD34(+) HPCs. Like KL, FL significantly enhanced the expansion of NK cells from CD34(+) HPCs in the presence of IL-15, compared with IL-15 alone. However, FL alone had no effect on NK cell differentiation. We therefore explored the mechanism by which FL promotes IL-15-mediated NK cell development. FL was found to induce IL-2/15Rbeta (CD122) expression on CD34(bright) HPCs. The CD34(bright) CD122(+) cell coexpressed CD38, but lacked expression of CD7, CD56, NK cell receptors (NKRs), or cytotoxic activity in the absence of IL-15. Using limiting dilution analysis in the presence of IL-15 alone, we demonstrated that the FL-induced CD34(bright)CD122(+) HPCs had an NK cell precursor frequency 20- to 60-fold higher than the CD34(dim/neg)CD122(-) HPCs and 65- to 235-fold higher than fresh CD34(+) HPCs. KL had similar effects as FL, but induced a significantly lower percentage of CD34(bright)CD122(+) cells (P </=.01). Both FL and KL also increased IL-15R transcript in CD34(+) HPCs. Culture of CD34(+) HPCs in FL or KL, followed by culture in IL-15 alone, induced expression of both C-type lectin and Ig-superfamily NKRs on CD56(+) cells. These data collectively support a role for FL in early human NK cell development. FL or KL generate a unique CD34(bright) CD122(+)CD38(+) human NK cell intermediate from CD34(+) HPCs that lacks NK features yet is IL-15-responsive. IL-15 is then required for the induction of CD56 and NKRs, LGL morphology, cytotoxic activity, and the ability to produce abundant cytokines and chemokines.

Adult↗
PubMed1998

Pathologic features of initial adenomas as predictors for metachronous adenomas of the rectum.

BACKGROUND: Colorectal cancer is the third most common cancer in the world, arising mostly from pre-existing adenomatous polyps (adenomas) of the large bowel. Patients with colorectal adenomas are at increased risk of colorectal cancer because of a high recurrence rate for adenomas. We followed a cohort of 1490 patients with rectal adenomas to determine whether recurrence might be related to pathologic characteristics of the initial adenomas. METHODS: The patients were identified in Haining County, China, from 1977 through 1978 by means of examination with a 15-cm rigid sigmoidoscope. They were followed by endoscopic examination at years 2, 4, 6, 11, and 16 after their initial polypectomy. New adenomas in the rectum were identified in 280 patients in these follow-up examinations. RESULTS: Statistically significant twofold to threefold elevated risks of metachronous (recurrent) adenomas were observed for patients who had more than two initial adenomas or whose most advanced initial adenoma was more than 1.0 cm in size, was of villous/tubulovillous type, or showed moderate to severe dysplasia. Much stronger associations were observed for advanced metachronous neoplasms, which are defined as cancers or adenomas with severe dysplasia, with multivariate adjusted relative risks (95% confidence interval) of 4.2 (1.8-9.9) for a large initial adenoma (>1.0 cm), 8.1 (4.2-15.6) for villous/tubulovillous architecture, and 14.4 (5.0-41.3) for severe dysplasia. In particular, patients who had a large (>1.0 cm) adenoma with severe dysplasia at baseline had a relative risk of 37 (7.8-174.7) of developing advanced metachronous neoplasms compared with patients who had small adenoma(s) with mild dysplasia. CONCLUSIONS: The risk of metachronous adenomas is closely related to the pathology of initial adenomas, thus allowing identification of a high-risk group of adenoma patients for close surveillance after their initial polypectomy.

Adenoma↗
PubMed1998

Distribution of orexin receptor mRNA in the rat brain.

The expression pattern of mRNA encoding two orexin receptors (OX1R and OX2R) in the rat brain was examined. OX1R and OX2R exhibited marked differential distribution. Within the hypothalamus, OX1R mRNA is most abundant in the ventromedial hypothalamic nucleus whereas OX2R is predominantly expressed in the paraventricular nucleus. High levels of OX1R mRNA were also detected in tenia tecta, the hippocampal formation, dorsal raphe, and locus coeruleus. OX2R mRNA is mainly expressed in cerebral cortex, nucleus accumbens, subthalamic and paraventricular thalamic nuclei, anterior pretectal nucleus. The presence of orexin receptor mRNA in the hypothalamus is in support of its proposed role in feeding regulation. Broad central distribution of orexin receptors may indicate additional functions for orexins.

Animals↗
PubMed1998

Induction of neuropeptide Y expression in dorsomedial hypothalamus of diet-induced obese mice.

Alterations of hypothalamic neuropeptide Y(NPY) and melanocortinergic functions in diet-induced obese (DIO) C57BL/6J mice were investigated by in situ hybridization. Compared with controls, the DIO mice displayed a profound induction (approximately 40-fold) of NPY expression in the dorsomedial (DMH) and ventromedial (VMH) hypothalamic nuclei, whereas the level of NPY mRNA in the arcuate nucleus (ARC) was reduced by 44%. The expression of pro-opiomelanocortin (POMC) and agouti-related protein was not significantly altered in the ARC of obese mice. Both excess body weight gain and altered hypothalamic NPY expression were reversible. We propose that the highly induced NPY expression in DMH and/or VMH may be a contributing etiological factor for the development of obesity and leptin resistance in the DIO mice.

Agouti Signaling Protein↗
PubMed1998

The nature of human immunodeficiency virus type 1 strand transfers.

The diploid nature of human immunodeficiency virus type 1 (HIV-1) suggests that recombination serves a central function in virus replication and evolution. A system was developed to examine HIV-1 strand transfers, including the obligatory DNA primer strand transfers as well as recombinational crossovers during reverse transcription. Sequence heterogeneity between different strains of HIV-1 was exploited for examining primer transfer events. Both intra- and intermolecular primer transfers were observed at similar frequencies during minus-strand DNA synthesis, whereas primer transfers during plus-strand DNA synthesis were primarily intramolecular. Sequence analysis of long terminal repeats from progeny proviruses also revealed a high rate of homologous recombination during minus-strand synthesis, corresponding to an overall rate of approximately three crossovers per HIV-1 genome per cycle of replication. These results imply that both viral genomic RNAs serve as templates during HIV-1 reverse transcription and that primer strand transfers and recombination may contribute substantially to the rapid genetic variation of HIV-1.

Base Sequence↗