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Biomedical subjects

Z Yu

Publications and source records attributed to Z Yu.

At least 307 records · Page 17Linked to original sources
PubMed1995

Induction of protective immunity against herpes simplex virus with DNA encoding the immediate early protein ICP 27.

Using a mouse zosteriform model that mimics human herpes simplex virus (HSV) infection in several aspects, the effectiveness of plasmid DNA encoding the immediate early protein ICP 27 was evaluated as a vaccine. Animals were immunized intramuscularly twice with DNA, then either challenged with virus or killed, and the nature of the immune response induced was measured. After intramuscular injection with plasmid DNA encoding ICP 27 (pc-ICP 27), solid protection was evident in 70-80% of mice and the lesions were delayed in the remaining animals. Immune splenocytes obtained from pc-ICP 27 immune mice showed HSV-specific lymphoproliferation, MHC-class I restricted cytotoxic T-lymphocyte (CTL) activity, and type 1 cytokine production. These animals also exhibited delayed-type hypersensitivity (DTH) reactions. Adoptive transfer studies conducted on syngeneic nude mice revealed that those recipients of immune CD4+ T cells, but not CD8+ T cells, were protected from subsequent HSV-1 (strain 17) challenge. Thus pc-ICP 27 DNA immunization protected the mice principally by CD4+ T cells and it is likely that these cells were Th-1 type because only type 1 cytokines were detectable after in vitro antigen stimulation. Our results indicate the potential value of DNA encoding nonstructural viral proteins as vaccines against HSV.

Animals↗
PubMed1995

Influence of hemodialysis membranes on gene expression and plasma levels of interleukin-1 beta.

Plasma levels of interleukin-1 beta (IL-1 beta) were measured in 10 normal subjects, in 11 nondialyzed end-stage renal failure (ESRD) patients, and in 22 hemodialysis (HD) patients. Of the HD patients, 7 were dialyzed with Cuprophan (CU), 7 with polymethylmethacrylate (PMMA), and 8 with polysulphone (PS) dialyzers. In normal controls, nondialyzed ESRD patients, and HD equipped with CU, PAMM, and PS dialyzers, plasma levels of IL-1 beta were 10.73 +/- 5.24 pg/ml, 9.97 +/- 3.61 pg/ml, 13.17 +/- 4.04 pg/ml, 15.16 +/- 6.16 pg/ml, and 13.96 +/- 5.47 pg/ml, respectively. There were no statistically significant differences among the groups (p > or = 0.05). In contrast, the gene expression of IL-1 beta for peripheral blood mononuclear cells (PBMC) by in situ hybridization showed differences among the groups. The gene for IL-1 beta for PBMC appears in HD equipped with different membranes, but not in cases of nondialyzed uremic patients and normal subjects. With computer imaging analysis, we carried out quantitative analysis of cells in in situ hybridization with an area of positive spots to an area of total cells. In HD with CU, PMMA, and PS, the results were 10.64 +/- 1.07, 3.34 +/- 0.74, and 3.27 +/- 0.64%, respectively. The levels of IL-1 beta gene expression in CU were higher than that in PMMA or PS. There were statistically significant differences (p < or = 0.001) between CU and PMMA or PS and no significant difference between the PMMA and PS (p > or = 0.05). We suggest measuring the gene expression of cytokines for PBMC and which may be better than measuring cytokine levels only for investigating the blood compatibility of dialyzers, which may help in understanding chronic complications of the dialysis procedure.

Adult↗
PubMed1995

Effect of dynamic loading methods on cement film thickness in vitro.

PURPOSE: Reduced cement flm thicknesses can improve crown seating and decrease marginal discrepancies. Improved marginal adaptation has the potential to reduce plaque accumulation, periodontal disease, and cement dissolution. Studies have indicated that dynamic seating methods can reduce seating discrepancies associated with zinc phosphate and resin cements. However, other types of cements and other dynamic techniques have not yet been studied or compared, nor has the mechanism for improved seating been fully explained. Therefore, the purpose of this study was to investigate the effect of a variety of loading methods on the film thicknesses of current types of crown and fixed partial denture cements compressed between glass plates. MATERIALS AND METHODS: This study investigated the effect of three dynamic loading methods on film thickness of six representative fixed prosthodontic cements. These included zinc phosphate, resin-modified glass ionomer, encapsulated glass ionomer, adhesive composite resin, composite resin, and polycarboxylate. The method was derived from American Dental Association specifications for cement film thickness. In control groups, the cements were placed between two glass glass plates and statically loaded with a 15-kg weight. The test groups were initially similarly loaded, and then for 30 seconds further subjected to simulated repeated patient opening and closing, vibrations from an electromallet, or an ultrasonic device. RESULTS: Mean film thicknesses ranged from 7.4 micrometers for polycarboxylate / ultrasound up to 40.3 micrometers for composite resin / static. Two-way analysis of variance revealed that the effects of material type and cementation method and their interaction all significantly affected film thickness (P < .0001). Multiple range analysis showed that dynamic methods were generally superior to static loading and that the ultrasonic method was the best overall. CONCLUSIONS: The different dynamic loading methods all significantly decreased cement film thicknesses between glass plates. The ultrasonic method was the most effective. The type of cement used also influenced film thickness. Composite resins were more affected than other materials.

Analysis of Variance↗
PubMed1995

[Treatment and prognosis of stage II testicular seminoma].

Sixty-five patients with stage II testicular seminoma treated from 1960 through 1990 were reviewed. According to Royal Marsden Hospital staging, there were 11 stage IIA, 13 stage IIB, and 41 stage IIC. Thirty Patients were treated with combination of radiotherapy and chemotherapy, 11 chemotherapy alone, 24 rediotherapy alone. The overall 5-year survival rate was 75.6%, with 100% for stage IIA, 92.3% for stage IIB and 62.9% for stage IIC. The differences were statistically significant. In stage IIC patients, there was no significant difference between those tumors > 10cm and < 10cm in diameter. Of the 41 IIC cases, 4 were treated with chemotherapy, 15 were treated with whole abdominal rediation, 22 with paraaortic and ipsilateral pelvic radiation. The 5-year survival rate was 91.7% and 51.2%, respectively. These differences was statistically significant. We recommand that stage IIC disease should be treated primarily with whole abdominal radiation. Regardless of the stage of the disease, prophylactic mediastinal irradiation did not influence the survival nor the relapse rate and may therefore be omitted.

Adult↗
PubMed1995

[Relationship between elevated plasma endothelin-1 level and renal function in patients with diabetic nephropathy].

Plasma endothelin-1 (ET-1) level was measured with radioimmunoassay in 33 normal subjects and 92 patients with different stages of diabetic nephropathy, consisting of 35 cases of diabetes mellitus with normal urinary albumin excretion (DM), 22 cases of incipient diabetic nephropathy (IDN), 22 cases of overt diabetic nephropathy (ODN), 8 cases with azotemia (DNa) and 5 cases with uremia (DNu). The results showed that plasma ET-1 levels in DNa and DNu groups (30.24 +/- 1.93 ng/L and 36.38 +/- 3.62 ng/L respectively) were significantly higher than those in other groups (P < 0.05); ET-1 level in ODN group (20.50 +/- 0.93 ng/L) was significantly higher than those in DM and IDN groups (P < 0.001); ET-1 level in IDN group was also significantly higher than that in DM group (17.79 +/- 0.74 vs. 15.06 +/- 0.63 ng/L, P < 0.01); All the above values were significantly higher than that in normal subjects (7.08 +/- 0.22 ng/L) (P < 0.001). There was significant positive correlation between ET-1 level and HbA1c, systolic pressure, diastolic pressure, blood urea nitrogen, serum creatine, uAER and a significant negative correlation between ET-1 level and glomerular filtration rate. It is shown that progressive elevation of plasma ET-1 level is closely related with different stages of renal function impairment, suggesting strongly the role of ET-1 in the development and progression of diabetic nephropathy.

Diabetic Nephropathies↗
PubMed1995

[Relative changes between calcium content and number of atrial specific granules induced by water and salt loading].

Rats prepared by either deprivation of water intake for 5 d or drinking 2% NaCl solution for 4 d were sacrificed for dissection of auricle, and making ultrathin sections. The numerical density (Nv) of atrial specific granules (ASG) were counted by using electron microscopic morphometry, and Ca concentration in ASG and in terminal cisterna of sarcoplasmic reticulum (TSR) was determined by using electron microscopic X-ray microanalysis. In the drinking 2% NaCl solution group, the Nv of ASG decreased from 6.02 +/- 2.30 to 2.96 +/- 1.62/microns 3 (P < 0.01) and all companied by a decrease of Ca concentration from 64 +/- 16 to 38 +/- 21 mmol/kg (P < 0.01), while the secretion of atrial natriuretic peptide (ANP) showed some increase. Water deprivation induced all the contrary results. However, the Ca concentration in TSR was not affected by water-salt loading. It is suggested that when the atrial cardiocytes were stimulated by salt loading, Ca in ASG was released into cytosol and thus promoted fusion of ASG membrane with sarcolemma which resulted in release of ANP. Therefore, it is considered that ASG as an intracellular Ca store participates in the stimulus-secretion coupling of ANP through the release of Ca ions.

Animals↗
PubMed1995

[Removal of petrous bone cholesteatoma and obliteration with adipose tissue].

Three cases of petrous bone cholesteatoma removed through translabyrinthine-cochlear approach with the surgical defect obliterated by using adipose tissue covered with superficial temporalis fasia flap were reported. The average follow-up period was two years without any sign of recurrence. The etiology, diagnosis and methods of surgical treatment were discussed.

Adipose Tissue↗
PubMed1995

[Clinical study of laryngeal and laryngopharyngeal cancers with ultra-weak chemiluminescence analysis].

Ultra-weak luminescence of serum in 30 normal persons and 40 patients (12 laryngeal cancers, 18 laryngopharyngeal cancers, and 10 benign tumour patients) was studied using SHG-1 type photobiological photometer. The results showed that the intensity in malignant tumour group was higher than that of the benign group, which in turn was higher than that of the normal group with significant statistical differences (P < 0.05). The study implied that ultra-weak luminescence test is of value in diagnosis of laryngeal and laryngopharyngeal cancers.

Adult↗
PubMed1994

In vitro characterization of nonpeptide irreversible inhibitors of HIV proteases.

The irreversible inhibition of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) proteases by 1,2-epoxy-3-(p-nitrophenoxy)propane (EPNP) and eight haloperidol derivatives has been studied. EPNP specifically inhibits HIV-1 and HIV-2 proteases with a stoichiometry of one EPNP molecule/dimeric enzyme. The site of modification of HIV-2 protease by EPNP has been unambiguously identified as Asp-25 using high performance tandem mass spectrometry. The haloperidol derivatives assayed consist of epoxides, ynones, and alpha,beta-unsaturated ketones. The Kinact values for these haloperidol derivatives range from 10.7 to 521 microM for HIV-1 protease and from 8.6 to 283 microM for the HIV-2 enzyme, being in some cases approximately 1000-fold more potent irreverisble inhibitors of HIV proteases than EPNP. This potency results from the haloperidol character of the compounds and the chemical reactivity of the groups capable of forming a covalent bond with the enzyme. Covalent modification of HIV-2 protease by a radiolabeled epoxide derivative of haloperidol, UCSF 84, is prevented by EPNP and the peptidomimetic transition state analog U-85548. In similar experiments, incorporation of UCSF 84 into HIV-1 protease is partially prevented by these active-site inhibitors. In contrast, a mutant HIV-1 protease, HIV-1 PR C95M, in which Cys-95 has been replaced by Met, is labeled 50% less than HIV-1 protease and is fully protected by EPNP and U-85548. These results indicate the presence of 2 reactive residues in HIV-1 protease: Cys-95 and another located in the active site of the enzyme. The alpha,beta-unsaturated ketone derivative of haloperidol, UCSF 191, which is stable over a broad pH range, was used to study the pH profile of inactivation of HIV-1 and HIV-2 proteases. Comparison of the profiles of inactivation of wild-type HIV-1 protease, HIV-1 PR C95M, and HIV-1 PR C67L as well as HIV-2 protease (which has no cysteine residues) reveals the contribution of Cys-95 to the reactivity of these irreversible inhibitors. The inhibitors UCSF 70, UCSF 84, UCSF 115, UCSF 142, and UCSF 191 reduce p55gag polyprotein processing when assayed in a mammalian cell line that produces HIV-1 viral particles lacking the envelope.

Amino Acid Sequence↗
PubMed1994

Determination of amide-type local anaesthetics by direct injection of plasma in a column-switching high-performance liquid chromatographic system using a pre-column with a semipermeable surface.

A high-performance liquid chromatographic method using column switching was applied to the direct determination of two local anaesthetics, ropivacaine and bupivacaine, in human plasma. The method is intended to be used in a combined LC-GC system; here only the LC-part is described. After addition of internal standard, the samples were filtered and directly injected into a semipermeable surface (SPS) pre-column where the analytes were strongly retained and separated from many endogenous compounds by a short washing step. The retained analytes were transferred by a buffered methanol phase from the pre-column into a carbonaceous HPLC column and they were detected by UV detection at 254 nm. The SPS pre-column could withstand numerous (> 200) direct injections of plasma samples (10 microliters). The method has a detection limit of 8.2 ng and requires a total assay time of 15 min per plasma sample. Quantitative recoveries were obtained over the range 3.3-114 micrograms/ml with inter-day precisions of 1.6-5.2% (C.V.).

Amides↗