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Biomedical subjects

Y Qiao

Publications and source records attributed to Y Qiao.

At least 19 recordsLinked to original sources
PubMed2001

Direct observation of capillary condensation of a solid.

We describe the direct condensation of a solid from vapor in an annular mica wedge. Neo-pentanol initially condenses as a liquid from 8 to 57 degrees C (the melting point T(m)), followed by nucleation of a solid from vapor for T<45 degrees C. Menthol (T(m) = 42 degrees C) gives only liquid condensates down to 12 degrees C. The adsorbed films of neo-pentanol, which unlike those of menthol show layering transitions, and the disordered crystalline phase of bulk neo-pentanol appear to facilitate condensation of the solid phase. There is evidence for a change in the nature of the solid neo-pentanol condensate with T.

Journal Article↗
PubMed2001

An intronic poly (AT) polymorphism of the DNA repair gene XPC and risk of squamous cell carcinoma of the head and neck: a case-control study.

Inherited polymorphisms of DNA repair genes may contribute to variations in DNA repair capacity and genetic susceptibility to cancer. In a hospital-based case-control study of 287 non-Hispanic white patients with newly diagnosed SCCHN and 311 control subjects matched on age, sex, ethnicity, and smoking status, we investigated the role of a newly identified variant allele of XPC, XPC-PAT+. We found that the frequency of the XPC-PAT+ allele was higher in the cases (0.409) than in the controls (0.333; P = 0.007). Fifty cases (17.4%) and 37 controls (11.9%) were XPC-PAT+/+, and 135 (47.0%) cases and 133 controls (42.8%) were XPC-PAT+/-. XPC-PAT+/- and XPC-PAT+/+ subjects were at significantly increased risk for SCCHN [adjusted odds ratios = 1.44 and 1.85, respectively (95% confidence intervals, 1.01-2.05 and 1.12-3.05, respectively; trend test, P = 0.007)]. We did not find ethnic difference in the frequency of XPC-PAT+ allele among four groups aged between 19 and 75 years: non-Hispanic whites, 294; African-Americans, 178; Hispanic-Americans, 103; and native Chinese, 119 (0.333, 0.281, 0.296, and 0.353, respectively). The case-control findings support the hypothesis that the XPC-PAT+ allele may contribute to the risk of developing SCCHN.

Aged↗
PubMed2001

Synthesis and biological activity of novel potent endothelin-converting enzyme-1 inhibitors.

Through directed screening of metalloprotease inhibitors, CGS 30084 (1) has been identified as a potent endothelin-converting enzyme-1 (ECE-1) inhibitor in vitro (IC50 = 77 nM). Herein we report the syntheses and biological activities of analogues derived from this lead, based on modifications of the biphenyl moiety. Compound 10, the thioacetate methyl ester prodrug derivative of compound 6m, was found to be an orally active and potent inhibitor of ECE-1 activity in rats.

Alanine↗
PubMed2001

Helicobacter pylori seropositivity and subsite-specific gastric cancer risks in Linxian, China.

BACKGROUND: Helicobacter pylori carriage (i.e., persistent exposure to the organism without gastric epithelial cell invasion) is an established risk factor for noncardia gastric cancer. However, its association with the risk of cancer of the gastric cardia is controversial. Consequently, we designed this prospective, nested case-control study to further explore the subsite-specific gastric cancer risks associated with H. pylori seropositivity (a surrogate marker for persistent exposure). METHODS: A total of 99 patients with gastric cardia cancer, 82 patients with noncardia gastric cancer, and 192 cancer-free subjects were selected from among the participants (n = 29 584) of a nutrition intervention trial previously conducted in Linxian, China. H. pylori seropositivity was determined by assaying for the presence of H. pylori whole cell and CagA antibodies in baseline serum samples from all subjects. Seropositivity was defined as one or both serum assays being positive. Odds ratios (ORs) for subsite-specific gastric cancer were estimated by multivariate logistic regression analyses. All statistical comparisons were two-sided (alpha =.05). RESULTS: H. pylori seropositivity rates for subjects with gastric cardia cancer, noncardia gastric cancer, and gastric cardia and noncardia cancers combined were 70% (P =.02), 72% (P: =.01), and 71% (P =.003) compared with 56% for cancer-free control subjects. OR estimates for H. pylori seropositivity were 1.87 (95% confidence interval [CI] = 1.10 to 3.17) for gastric cardia cancer, 2.29 (95% CI = 1.26 to 4.14) for noncardia gastric cancer, and 2.04 (95% CI = 1.31 to 3.18) for gastric cardia and noncardia cancers combined. CONCLUSIONS: H. pylori seropositivity was associated with increased risks for both gastric cardia cancer and noncardia gastric cancer in this well-characterized cohort. Thus, H. pylori carriage may increase the risk of cancer throughout the stomach.

Adenocarcinoma↗
PubMed2001

Enhanced continent mechanism of tapered ileum by extramural support from the pouch and abdominal walls: a preliminary report of a clinical study.

PURPOSE: We constructed a reliable continent tube that is easy to catheterize and surgically simple. MATERIALS AND METHODS: Eight patients with bladder cancer underwent a procedure in which ileal segment was tapered as an efferent tube, of which a part was placed between the back surface of the rectus muscle and the ileal pouch wall. The internal orifice of the tapered ileum was anastomosed to the ileal pouch and its external orifice was anastomosed to the umbilicus. Urodynamic and radiological studies were done postoperatively in 7 cases. RESULTS: The stoma was easily catheterized with a 16Fr catheter in all cases. One patient died of heart disease 55 days postoperatively, while 6 of the remaining 7 were completely continent day and night. Urodynamic study of the efferent tubes showed that maximum close pressure with the pouch full was significantly higher than with the pouch empty (p <0.001). Retrograde radiography of the efferent tubes demonstrated perfect canalization without stenosis. CONCLUSIONS: This study indicates that the continent mechanism of tapered ileum may be greatly enhanced by fixing it between the abdominal and pouch walls. This maneuver also provides easy catheterization and surgical simplicity.

Abdominal Muscles↗
PubMed2000

Design and synthesis of potent thiol-based inhibitors of endothelin converting enzyme-1.

Through directed screening of compounds prepared as metalloprotease inhibitors a compound, CGS 30084, that had potent endothelin converting enzyme-1 (ECE-1) in vitro inhibitory activity (IC50 = 77 nM) was identified. Herein we report the synthesis and optimization of ECE-1 inhibitory activity of additional analogues from this lead. Compound 3c, the thioacetate methyl ester derivative of compound 4c, was found to be a long acting inhibitor of ECE-1 activity in rats after oral administration.

Animals↗
PubMed2000

Differentiation of monocytes to macrophages switches the Mycobacterium tuberculosis effect on HIV-1 replication from stimulation to inhibition: modulation of interferon response and CCAAT/enhancer binding protein beta expression.

HIV-1 replication is inhibited in uninflamed lung macrophages and is stimulated during tuberculosis. Attempts to recapitulate activation of HIV-1 replication in primary monocytes and macrophages ex vivo and in the untreated and PMA-treated THP-1 cell line model in vitro have produced opposite results depending on the state of differentiation of the cells. After infection with Mycobacterium tuberculosis, monocytes enhanced HIV-1 replication and produced a stimulatory 37-kDa CCAAT/enhancer binding protein beta (C/EBPbeta) transcription factor, whereas macrophages suppressed HIV-1 replication and produced an inhibitory 16-kDa C/EBPbeta transcription factor. IFN-beta induced inhibitory 16-kDa C/EBPbeta in macrophages, but had no effect on C/EBPbeta expression in monocytes. Macrophages, but not monocytes, were able to activate IFN-stimulated gene factor-3 (ISGF-3), a transcription factor composed of STAT-1, STAT-2, and IFN regulatory factor (IRF)-9, after infection with M. tuberculosis or stimulation with type I IFN. Macrophages expressed IRF-9 DNA-binding activity, but monocytes did not, and addition of the IRF-9 component reconstituted ISGF-3 in extracts of IFN-treated monocytes. Modulation of IFN responsiveness upon differentiation occurred at least in part through a post-transcriptionally regulated increase in IRF-9 expression. Both monocytes and macrophages maintained IFN responsiveness, activating STAT-1 homodimer formation and transcription of the STAT-1 gene after IFN stimulation. In addition, both monocytes and macrophages were able to activate NF-kappaB upon infection with M. tuberculosis. These results show that induction of ISGF-3, expression of the inhibitory 16-kDa C/EBPbeta, and suppression of HIV-1 replication via a transcriptional mechanism are macrophage-specific responses to infection with M. tuberculosis.

CCAAT-Enhancer-Binding Proteins↗
PubMed2000

[Bcl-2 anti-sense oligonucleotide sensitizes Fas-mediated apoptosis of gastric cancer cells].

OBJECTIVE: To study the effect of bcl-2 anti-sense oligonucleotide on the sensitivity of gastric cancer cells to Fas-mediated apoptosis. METHODS: Gastric cancer cell line MKN45 was transfected with bcl-2 anti-sense oligonucleotide, and expression of bcl-2 was examined by Western blotting. Agonistic Fas antibody was used to induce apoptosis detected by TUNEL staining and flow cytometry. RESULTS: Bcl-2 expression in MKN45 cells transfected with bcl-2 anti-sense oligonucleotide was markedly inhibited. When cultured with antibody apoptosis index of the anti-sense oligonucleotide-treated MKN45 cells was 55.6% +/- 4.7% (n = 5), which was significantly higher than that of the control (8.4% +/- 2.1%, n = 5). CONCLUSION: Expression of bcl-2 in gastric cancer cells may antagonize Fas-mediated apoptosis.

Apoptosis↗
PubMed1999

Design and synthesis of thiol containing inhibitors of matrix metalloproteinases.

A series of thiol containing derivatives was prepared. Several of these compounds were found to inhibit matrix metalloproteinases 1, 3, and 9 with selectivity towards 3 and 9. Compounds 15, 20, and 22 were administered to rats orally at 75 mumol/kg. Drug levels of compounds 20 and 22 in the plasma were found to exceed the IC50 values for MMP 3 and 9 four hours after administration.

Animals↗
PubMed1996

Mercaptoacyl dipeptides as orally active dual inhibitors of angiotensin-converting enzyme and neutral endopeptidase.

Dual inhibitors of the two zinc metallopeptidases, neutral endopeptidase (NEP, EC 3.4.24.11) and angiotensin-I-converting enzyme (ACE, EC 2.4.15.1), have been the focus of much clinical interest for the treatment of hypertension and congestive heart failure. We have previously reported that compound 2 (N-[[1-[(2(S)-mercapto-3-methyl-1-oxobutyl) amino]-1-cyclopentyl]-carbonyl]-L-tyrosine) was a potent dual inhibitor in vitro (IC50 (ACE) = 7.0 nM, IC50 (NEP) = 1.5 nM) (Fink et al. J. Med. Chem. 1995, 38, 5023-5030). This compound was found to have oral activity; however, its duration of effect was short. A series of thioacetate carboxylic acid ester analogs of compound 2 was prepared. Modifications were also made to the tyrosine phenol. These compounds were evaluated for their ability to inhibit plasma ACE activity when administered orally to conscious normotensive rats. Most of the compounds prepared were found to be orally active with longer durations of effect than compound 2. Compound 38 (N-[[1-[(2(S)-(acetylthio)-3-methyl-1-oxobutyl) amino]-1-cyclopentyl]carbonyl]-O-methyl-L-tyrosine ethyl ester), administered at 11.7 mg/kg po, was found to be more efficacious than captopril at 10 mg/kg po. This compound was also found to inhibit plasma NEP activity following oral administration to conscious rats and was more efficacious than acetorphan. Compound 38 was found to lower blood pressure in the aorta-ligated rat and the spontaneously hypertensive rat when administered orally. The synthesis and biological activity of these dual inhibitors are discussed.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

New alpha-thiol dipeptide dual inhibitors of angiotensin-I converting enzyme and neutral endopeptidase EC 3.4.24.11.

Dual inhibitors of the two zinc metallopeptidases, neutral endopeptidase (NEP, EC 3.4.24.11) and angiotensin-I converting enzyme, have been the focus of much clinical interest for the treatment of hypertension and congestive heart failure. A novel series of alpha-thio dipeptides containing central cyclic non-natural amino acids were prepared and were evaluated for their ability to inhibit these two metallopeptidases in vitro and in vivo. Most of these compounds were found to be excellent dual inhibitors of ACE and NEP in vitro and several were also found to inhibit angiotensin-I (AI) pressor response in conscious rats when given by intravenous administration. Compound 6n, one of our most potent dual inhibitors in vitro, was found to be more efficacious than captopril in the AI pressor experiment when administered orally to conscious rats. This compound was also found to inhibit plasma NEP activity following oral administration to conscious rats and was more efficacious than acetorphan. The structure-activity relationships and biological activity of these dual inhibitors will be discussed.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

dinP, a new gene in Escherichia coli, whose product shows similarities to UmuC and its homologues.

A new gene, designated dinP, was found during E. coli genomic sequencing around the 5.5 min region. Its coding region is preceded by a sequence similar to the consensus binding sequence for LexA, the so-called SOS box sequence. The amino acid sequence of DinP (351 amino acid residues) has a strong similarity to the C. elegans hypothetical protein F22B7.6 and weaker similarities to the UmuC homologues in E. coli and Salmonella typhimurium and also to REV1 of Saccharomyces cerevisiae. Another SOS operon (dinJ1 and dinJ2 genes) found in this region is also described.

Amino Acid Sequence↗
PubMed1995

[Two autopsy cases of malignant mixed müllerian tumor of the uterus with metastasis to alimentary tract and liver].

Two autopsy cases (69 and 87-year-old women) of malignant mixed müllerian tumor (MMMT) following radiation therapy for uterine cervical cancer sixteen and twenty years ago respectively were reported. They were admitted due to abdominal pain and diagnosed as ileus. In the first case, CT examination revealed a tumor measuring about 8 x 10 cm in size in the uterine posterior wall. Recurrence of the uterine cancer was suspected and hysterooophorectomy combined with sigmoidectomy was performed. In the second case, artificial anus formation was performed because of sigmoid stricture by the invasion of the tumor. Histologically, tumors in both cases were composed of carcinomatous and sarcomatous components including heterologous elements such as cartilage. The patients died of extensive spreads and metastasis in the liver and alimentary tract.

Aged↗
PubMed1995

Cell damage and liberation of nitric oxide synthase in rat heart induced by endotoxin administration.

To evaluate the relationship between cardiovascular injury and the pathological aspect of the liberation of the nitric oxide synthase in endotoxin shock, Wistar rats were injected intraperitoneally with 10 mg/kg E. coli endotoxin and the cardiovascular changes were observed chronologically by immunohistochemical and electron microscopic techniques at 2, 4, 8 and 12 h respectively after endotoxin administration. Light microscopically, irregular contraction of cardiomyocytes was observed in the early stage. After 8 h of endotoxin administration, occasional disintegration of the myocytes as well as lysis of myofibrils became prominent, and diminished stainings of myoglobin and actin were seen in these myocytes. Ultrastructurally, increased pinocytotic vesicles were observed in endothelial cells associated with widened intercellular spaces, and vacuolization of endothelial and medial cells of the vasculature. In cardiomyocytes, swelling of mitochondria and interstitial edema were noted at 12 h after endotoxin administration. Immunohistochemically, an increased permeability of albumin was noted in the myocytes and vasculature and nitric oxide synthase was localized on the cytomembrane of the endothelium of the coronary arteries in control rats. After endotoxin administration, the reaction products of nitric oxide synthase increased in the endothelial and medial cells, and cardiomyocytes. These results suggest that the increased activity of nitric oxide synthase is an important factor in the excessive production of nitric oxide and in promoting the pathologic changes in the cardiovascular system after endotoxin administration.

Animals↗