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Biomedical subjects

D Yu

Publications and source records attributed to D Yu.

At least 109 records · Page 6Linked to original sources
PubMed2000

Anticalculus effect of two zinc citrate/essential oil-containing dentifrices.

PURPOSE: To assess the feasibility of incorporating zinc citrate, a known anticalculus ingredient, into a dentifrice formulation containing a fixed combination of essential oils, a known antiplaque/antigingivitis agent. MATERIALS AND METHODS: This randomized, parallel, double-blind study evaluated the potential of two essential oil dentifrice formulations containing different levels of zinc citrate (1.0% and 2.0% ZCT) to reduce supragingival calculus formation compared to a marketed control dentifrice, Crest Regular. Following a 3-month pre-test phase, subjects received a dental prophylaxis, were stratified into three balanced groups on the basis of Volpe-Manhold calculus scores and brushed twice daily with their assigned dentifrice for 3 months. RESULTS: One hundred ninety-six evaluable subjects completed all phases of the study. ANCOVA revealed that the 1.0% ZCT and 2.0% ZCT essential oil dentifrice formulations provided significant reductions in calculus formation of 26.4% and 29.0% (P< 0.001), respectively, compared to the control dentifrice, Crest Regular. The magnitude of calculus reductions is similar to those levels obtained by other zinc salt formulations.

Adolescent↗
PubMed2000

Caries inhibition efficacy of an antiplaque/antigingivitis dentifrice.

PURPOSE: To evaluate the efficacy of a fluoride dentifrice containing a fixed combination of essential oils (Thymol, Menthol, Eucalyptol, and Methyl Salicylate) in preventing caries in Sprague Dawley rats. MATERIALS AND METHODS: The dentifrice contains 0.76% sodium monofluorophosphate (SMFP) as the fluoride source and a silica abrasive system. A fluoride-free placebo and a clinically proven USP dentifrice reference standard for SMFP/silica were included as controls. Three groups of 45 SDV-free Sprague Dawley weanlings were infected by a cariogenic strain of Streptococcus sobrinus and fed cariogenic diet NIH 2000 ad libitum. Animals were treated twice daily (once on weekends) with the assigned dentifrice using a cotton-tipped applicator, for 5 wks, after which they were terminated and caries scored using Larson's modification of the Keyes method. RESULTS: Analyses of variance were used to compare inter-group means, the total E lesion score was the primary efficacy variable. Compared with the fluoride-free vehicle control, the experimental dentifrice and USP reference standard dentifrice produced a statistically significant reductions of 18.3% and 12.2% respectively for total caries score (P<0.001). Compared with the clinically tested USP positive control dentifrice, the experimental dentifrice produced a statistically significant reduction in the total caries score of 6.9% (P=0.028). The results of this study show that 1) both the new dentifrice containing essential oils and USP dentifrice are statistically significantly effective in reducing caries in the rat model, 2) the anticaries activity of the SMFP dentifrice is not adversely affected with the addition of essential oils.

Analysis of Variance↗
PubMed2000

Stain removal efficacy of two new fluoride dentifrices containing essential oils.

PURPOSE: To assess in vitro the stain removal efficacy of two new antiplaque/antigingivitis dentifrices utilizing a modification of a previously validated Stookey method. MATERIALS AND METHODS: The modifications to the original Stookey method are the following: (1) study design; three 5 x 5 Latin Squares were employed to minimize bias stemming from position or test run in the study. (2) statistical success criteria; a test formulation was judged to be effective if the lower one-sided 95% confidence limit was "equal to or higher than" 50 since a minimum PCR (pellicle cleaning ratio) score of 50 is needed for a dentifrice to show clinical efficacy. The two test dentifrice formulations contained a fluoride source, a silica abrasive system, and four essential oils. The ADA reference abrasive material (calcium pyrophosphate) and placebo toothpaste were included as positive and negative controls, respectively. RESULTS: Compared to the negative control, the positive control exhibited a statistically higher PCR score; therefore, the validity of this modified Stookey method was confirmed. Additionally, the lower limits of the one-sided 95% confidence interval for the two dentifrice formulations were above the threshold PCR of 50; therefore, this modified Stookey method should predict that both essential oil-containing dentifrices possess acceptable stain removal power.

Analysis of Variance↗
PubMed2000

P16 overexpression in pituitary adenomas studied by immunohistochemistry and in situ hybridization.

OBJECTIVES: To examine the expression of p16 gene and the clinicopathological characteristics of 31 pituitary adenomas. To investigate the relationship between p16 expression and cell proliferative activity by analyzing the expression of proliferating cell nuclear antigens (PCNA). METHODS: Immunohistochemistry and in situ hybridization were performed on freshly-prepared paraffin-embedded specimens of 31 pituitary adenomas. RESULTS: Varying degrees of overexpression of the p16 gene was found in the tumors specimens. A higher proportion of p16 positive tumor cells was associated with bigger size, more frequent invasion and higher recurrence of the tumors. The expression of p16 was found to be significantly associated with the degree of PCNA expression. CONCLUSION: Though inactivation of the p16 gene is known in wide range of tumors, our study suggested that p16 overexpression might play a role in the development and progression of pituitary adenomas.

Adenoma↗
PubMed2000

[Study on the application of random amplified polymorphic DNA in Yersinia pestis genotyping].

OBJECTIVE: To study the type of 103 Y. pestis strains that isolated from different plague foci and different ecological types. METHOD: Random amplified polymorphic DNA (RAPD) was used. RESULTS: Y. pestis were divided into two RAPD types: most strains that isolated from elsewhere in the country belonged to RAPD-1 type, while most strains that isolated from Qinghai province were RAPD-2 type. CONCLUSION: The genome structures of different ecotype Y. pestis were different providing the foundation of further research and prevention of plague.

Animals↗
PubMed2000

[Drinking water types, microcystins and colorectal cancer].

OBJECTIVE: To assess the relationship between microcystins (a blue-green algal toxin) in drinking water and colorectal cancer. METHODS: Eight townships were randomly selected as study sites in Haining city of Zhejiang province, China. Four hundred and eight colon and rectum carcinoma cases diagnosed from 1977 to 1996 were identified from cancer registry in the study sites. A retrospective survey on types of drinking water of all 408 cases was conducted. Population data and drinking water sources data were provided by local household registration and local health institution, respectively. Water samples from different sources (well, tap-water, river and pond) were collected and microcystins concentrations were measured by an indirect competitive ELISA method. RESULTS: The incidence rates of colorectal cancer were significantly higher among people drinking river or pond water than those who drank well water or tap-water in both males and females. And comparing with other sources to well water, the relative risks (RR) were much higher for people using river water (7.94) and pond water (7.70). The positive detection rates (> 50 pg/ml) of microcystin in well, tap-water, river and pond water were 0.00%, 0.00%, 36.23% and 17.14% respectively. The highest concentrations of microcystins were 1 083.43 pg/ml (river) and 1 937.94 pg/ml (pond) in the positive samples. Microcystins concentrations in river and pond were significantly higher than the concentrations in well and tap water (P < 0.01). The Spearman rank correlation analysis showed that in the study sites, the microcystins concentrations of river and pond water were positively correlated with the incidence of colorectal cancer (r = 0.881, P < 0.01). CONCLUSION: Drinking surface water (river or pond) is one of the risk factors for colorectal cancer. Microcystins may be associated with incidence of colorectal cancer. It is suggested that further study should be carried out to clarify the relationship between colorectal cancer and microcystin in drinking water.

Bacterial Toxins↗
PubMed2000

[Effects of fluoride on the expression of c-fos and c-jun genes and cell proliferation of rat osteoblasts].

OBJECTIVE: To investigate the effects of sodium fluoride (NaF) on the expression of c-Fos and c-Jun genes and osteoblast cell proliferation of rat osteoblasts. METHODS: Osteoblastic cells were isolated from baby rat calvaria, and cultured in the presence of different doses of NaF (10(-5) mol/L, 10(-4) mol/L, and 10(-3) mol/L). Cell proliferation was measured by the MTT method, and c-Fos and c-Jun expression was detected by the immunohistochemistry combined with image analysis compute system. RESULTS RESULTS: from the MTT assay showed that NaF increased the proliferation of rat osteoblast and induced the expression of c-Fos and c-Jun genes. The increases of c-Fos and c-Jun expression by the 3 different doses of NaF were 5.4%, 15.4% and 42.3% for the c-Fos gene and 12.1%, 14.4% and 38.6% for c-Jun gene respectively (P < 0.05 and P < 0.01). CONCLUSION: NaF increased rat osteoblastic cell proliferation and the expression of genes involved in cell proliferation.

Animals↗
PubMed2000

[The outcome of 1268 cases of endoscopic sinus surgery].

OBJECTIVE: To evaluate the curative effect of endoscopic sinus surgery (ESS). METHODS: One thousand two hundred and sixty-eight cases with chronic sinusitis and nasal polyps undergone ESS from 1989 to 1997 were appraised with the standard criteria (Chinese ENT Association, 1997). There were 366 cases(28.9%) in type 1, 646 cases(50.9%) in type 2 and 256 cases(20.2%) in type 3. One thousand two hundred and sixty-two cases underwent ESS under intranasal local anesthesia and sedation; 182 cases underwent submucous resection of nasal septum or septoplasty. Long-term follow-up was performed at 9 to 42 months(mean = 15 months). RESULTS: The results showed that cure rate was 93.7% for type 1, 81.6% for type 2 and 68.4% for type 3. There was significant difference in cure rate among different types (P < 0.01). Complication of ESS in 1,268 cases occurred in 2.3%. CONCLUSION: ESS is efficacy and safe in the treatment of nasal polyps and chronic sinusitis. The cure result is directly related to the types of the disease.

Adult↗
PubMed2000

[T-lymphocyte subsets and inflammatory cytokines of interleukin-5 and interleukin-10 expression in human nasal polyp tissue].

OBJECTIVE: To investigate the distribution of T-lymphocyte subsets (CD4+ and CD8+ cells) and the expression of IL-5 and IL-10 protein-positive cells in nasal polyps. METHODS: The specimens of thirty-two nasal polyps and six control subjects were studied by Immunohistochemical method to detect CD4+, CD8+, IL-5+ and IL-10+ cells. A mean numbers of positive cells per high power field (10 x 40) were counted. All data were analyzed with t-test and correl-test. RESULTS: There were significantly large number of CD4+ and CD8+ cells in nasal polyps (P < 0.001). A significant predominance of CD4+ cells over CD8+ cells was found in the two subgroups (subepithelia, arounding glands and blood vessels) of nasal polyp (P < 0.001). There were an abundant number of IL-5+ IL-10+ cells, whereas significantly difference higher concentrations than that in the controls (P < 0.001). IL-5+ cells were more than IL-10+ cells in nasal polyps (P < 0.05), and most of IL-5+ cells were plasmacytes and lymphocytes. There was a significant correlation between the counts of CD4+/CD8+ and IL-5+/IL-10+ in the subgroup of nasal polyps arounding glands and blood vessels (r = 0.78, P < 0.01). CONCLUSIONS: This study indicated that CD4+ T-lymphocytes and IL-5 high expression may play an important role in the nasal polyps. Migration of plasmacytes and lymphocytes in polyps may participate in the inflammatory reaction. The disturbance of cellular and humoral immunity and imbalance of cytokines distribution may play a crucial role in the pathogenesis of nasal polyps.

Adult↗
PubMed2000

[Calcium activated non-selective cation channel in endothelial cell line ECV304 and inhibition of tumor necrosis factor-alpha].

OBJECTIVE: To study the character of non-selective cation channel in human umbilical cord vein endothelial cell line ECV304 and the effect of tumor necrosis factor-alpha (TNF-alpha) on channel activity. METHOD: Patch clamp technique was used to record single channel and whole cell currents. RESULTS: This channel can be activated by calcium, channel conductance was (19.74 +/- 2.35) pS and its Po was 0.260 +/- 0.006 (n = 5). 100 U/ml TNF-alpha inhibited channel activity, showing that conductance reduced to (10.69 +/- 4.68) pS and Po reduced to 0.230 +/- 0.051 (n = 5). Results in whole-cell configuration were consistent with that in cell-attached patches. Currents were obviously blocked by Cl- channel inhibitor anthracene-9-carboxylic acid (A9C). In order to testify the character of this channel further, KCl and NaCl were exchanged by K(+)-Aspartate in pipette solution. Under this condition, the single channel activities as before were recorded again. Its conductance was (18.33 +/- 2.98) pS(n = 8), and TNF-alpha as well as A9C could inhibit channel activity. But this channel activity could not be blocked by another Cl- channel blocker Zn2+. In the condition of K-Asparate replaced by CsCl in solution, identical channel activity as before could not be recorded. It seemed that Cs+ could not pass through this cation channel. CONCLUSION: It is inferred that calcium-activated non-selective-action channel recorded in endothelial cell ECV304, can be inhibited by TNF-alpha and A9C.

Anthracenes↗
PubMed2000

Inhibitory effect of fluvastatin on aortic intimal thickening in normocholesterolemic rabbits.

OBJECTIVE: The anti-atherosclerotic effect of fluvastatin at does insufficient to lower serum cholesterol on the catheter-induced intimal thickering and possible mechanism were investigated in abdominal aorta of rabbits. METHODS: Fifty-six rabbits were randomly divided into eight groups (n = 7, each). Fluvastatin was given mixed with food at daily dose of 8 mg/kg starting 5 days before catheterization. Light microscope, immunohistochemistry, transmission electron microscope and RT-PCR assay were applied to assess vascular smooth muscle cell (VSMC) proliferation and apoptosis, as well as oncogene expression in vascular wall. RESULTS: At day 10 and day 15 after catheter induced denudation intima/media (I/M) thickness ratio was obviously higher, and also the percentage of PCNA-positive cells and TUNEL-positive cells in media was significantly higher compared with controls. The intimal hyperplasia was mostly composed of alpha-SM-actin-positive cells. In rabbits given fluvastatin I/M ratio and the percentage of these positive cells significantly decreased compared with those without fluvastatin. The overexpression of proto-oncogene H-ras mRNA and decreased expression of anti-oncogene p53 mRNA were found after vascular injury, whereas fluvastatin significantly reduced H-ras mRNA and increased p53 mRNA expression. CONCLUSION: Proliferation of VSMC in the media and the migration to the intima can be inhibited, and apoptosis of VSMC be induced by short-term use of fluvastatin after balloon catheter denudation, independent of serum lipid change. The underlying mechanism is presumably associated with the influence of fluvastatin on oncogene expression in the injured vascular wall.

Animals↗
PubMed2000

Nitric oxide inhibits a rise of ATP-introduced cytosolic free Ca2+ concentration and release from intracellular stored Ca2+.

OBJECTIVE: The effects of ATP-introduced a rise in cytosolic free Ca2+ concentration and inhibition of nitric oxide were investigated. METHOD: Measurement of free Ca2+ ([Ca2+]i) of cultured rat tail arterial smooth muscle cells using Fura-2/AM dual excitation wavelength spectrofluorometer. RESULTS: There are two components of [Ca2+]i can be evoked by ATP. One part is Ca2+ entry from Ca2+ channel and formed a plateau. The another part is a peak that released from Ca2+ store. Both of them can be inhibited by NO. CONCLUSION: The ATP induced [Ca2+]i rise that release Ca2+ from both Insp3 and ryanochine receptors and Ca2+ entry through calcium channels. The inhibition of NO on ATP induced [Ca2+]i rise that was mediated by cGMP.

Adenosine Triphosphate↗
PubMed2000

[Damage mechanisms of molecule in DNA aqueous solution induced by ultraviolet radiation].

After ultraviolet radiation treated at various time, the Raman spectra of herring sperm DNA in aqueous solution were presented. The analytic results showed that first, the out-ring amino group numeration of cytosine C4 site have reducing in the form of Raman hypochromicity; but C4O ketone group of derivative uracil assumed have not emerge with Raman hyperchromiciuy, in UV-induced DNA only with water molecule join in; second, the electron cloud of the main-groove side in pyrimidine ring have a tendency of slanting toward C6 site, which was beneficial to the deamination of C-->U transition, after some cytosine formed dipyrimidine with another adjacent pyrimidine; and third, with UV radiation, the characteristic peak 616 cm-1 of uracil N3C4 has arisen. Its very important, because the quality of the N3C4 bond have a great difference between cytosine and uracil. The result have not supported the model that cytosine can direct to be come off amino group for form the ketone type uracilo depend on UV-induced, therefore we have found that the process of get involved in imino tautomer state was probable exist by Raman spectroscopic technique.

DNA Damage↗
PubMed1999

Site of chemical modifications in CpG containing phosphorothioate oligodeoxynucleotide modulates its immunostimulatory activity.

Phosphorothioate oligodeoxynucleotides containing CpG motifs have immunostimulatory activity. Appropriate substitution of deoxynucleosides in the flanking region of CpG-containing phosphorothioate oligodeoxynucleotides with 2'-O-methylribonucleosides results in significant decreases or increases in their immunostimulatory activities. The results provide insights in how to chemically modify phosphorothioate oligodeoxynucleotides containing CpG motifs to suppress or enhance their immunostimulatory activity for different therapeutic uses.

Adjuvants, Immunologic↗
PubMed1999

Antitumor activity and pharmacokinetics of a mixed-backbone antisense oligonucleotide targeted to the RIalpha subunit of protein kinase A after oral administration.

Overexpression of the RIalpha subunit of cAMP-dependent protein kinase (PKA) has been demonstrated in various human cancers. PKA has been suggested as a potential target for cancer therapy. The goal of the present study was to evaluate an anti-PKA antisense oligonucleotide (mixed-backbone oligonucleotide) as a therapeutic approach to human cancer treatment. The identified oligonucleotide inhibited the growth of cell lines of human colon cancer (LS174T, DLD-1), leukemia (HL-60), breast cancer (MCF-7, MDA-MB-468), and lung cancer (A549) in a time-, concentration-, and sequence-dependent manner. In a dose-dependent manner, the oligonucleotide displayed in vivo antitumor activity in severe combined immunodeficient and nude mice bearing xenografts of human cancers of the colon (LS174T), breast (MDA-MB-468), and lung (A549). The routes of drug administration were intraperitoneal and oral. Synergistic effects were found when the antisense oligonucleotide was used in combination with the cancer chemotherapeutic agent cisplatin. The pharmacokinetics of the oligonucleotide after oral administration of (35)S-labeled oligonucleotide into tumor-bearing mice indicated an accumulation and retention of the oligonucleotide in tumor tissue. This study further provides a basis for clinical studies of the antisense oligonucleotide targeted to the RIalpha subunit of PKA (GEM 231) as a cancer therapeutic agent used alone or in combination with conventional chemotherapy.

Administration, Oral↗
PubMed1999

Brain-specific differentiation of mouse yolk sac endothelial cells.

Vascular endothelial cells exhibit diverse functional and biochemical properties that vary among tissues and organs, suggesting that differentiation of endothelial cells is influenced by their microenvironment. In this study, relatively undifferentiated endothelial cells from 9-day embryonic mouse yolk sac were co-cultured with 12-day embryonic mouse brain rudiments. Organ-specific differentiation of the yolk sac endothelial cells was monitored based on the expression and functional activities of two brain-specific endothelial cell markers, glucose transporter 1 (Glut-1) and P-glycoprotein. Immunochemical staining, semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and functional assays demonstrated that yolk sac endothelial cells can acquire brain-specific properties after induction by brain rudiments. This result provides support for the hypothesis that endothelial cell heterogeneity is acquired during organogenesis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

Effects of structure on alpha C-H bond enthalpies of amino acid residues: relevance to H transfers in enzyme mechanisms and in protein oxidation.

The bond dissociation enthalpies (BDE) of all of the amino acid residues, modeled by HC(O)NHCH(R)C(O)NH(2) (PH(res)), were determined at the B3LYP/6-31G//B3LYP/6-31G level, coupled with isodesmic reactions. The results for neutral side chains with phi, psi angles approximately 180 degrees, approximately 180 degrees in ascending order, to an expected accuracy of +/-10 kJ mol(-)(1), are Asn 326; cystine 330; Asp 332; Gln 334; Trp 337; Arg 340; Lys 340; Met 343; His 344; Phe 344; Tyr 344; Leu 344; Ala 345; Cys 346; Ser 349; Gly 350; Ile 351; Val 352; Glu 354; Thr 357; Pro-cis 358; Pro-trans 369. BDEs calculated at the ROMP2/6-31G//B3LYP/6-31G level exhibit the same trends but are approximately 7 kJ mol(-)(1) higher. All BDEs are smaller than those of typical secondary or tertiary C-H bonds due to the phenomenon of captodative stabilization. The stabilization is reduced by changes in the phi,psi angles. As a result the BDEs increase by about 10 kJ mol(-)(1) in beta-sheet and 40 kJ mol(-)(1) in alpha-helical environments, respectively. In effect the alpha C-H BDEs can be "tuned" from about 345 to 400 kJ mol(-)(1) by adjusting the local environment. Some very significant effects of this are seen in the current literature on H-transfer processes in enzyme mechanisms and in oxidative damage to proteins. These observations are discussed in terms of the findings of the present study.

Amino Acids↗