Biomedical subjects

Z Zhao

Publications and source records attributed to Z Zhao.

At least 199 records · Page 11Linked to original sources

PubMed1998

[The application of the pedicled buccal fat pad graft in cleft palate repair].

OBJECTIVE: The purpose of this paper is to provide the experience in using the pedicled buccal fat pad (BFP) graft in cleft palate repair when healing by secondary intention may need to be considered due to the width of the cleft; the qualitative or quantitative tissue constraints, the dead cavity between the oral and nasal layers or single layer closure of the hard palate with the vomer and marginal pedicled mucosoperiosteal flap. METHODS: The body and buccal extension of BFP is gently torn out from its bed and advanced into the palate vault around the posterior aspect of the maxilla to cover the raw surface of the hard palate cleft and/or fill the dead cavity between the oral and nasal tissue layers, specifically in the conjunction of the hard and soft palate. RESULTS: Six cleft palates were repaired with the BFP graft. The postoperative course was uneventful. The BFP graft is viable without the occurrence of fistula or infection. CONCLUSION: The pedicled BFP graft has provided an excellent soft tissue support for secondary epithelialization when primary dehiscence has or would have otherwise thwarted ultimate closure of the palatal defect. The pedicled BFP graft permits closure of palatal defects that could not be repaired by conventional procedures.

Adolescent↗

PubMed1998

[Cytokines release related to cardiopulmonary bypass in patients with prosthetic valve replacement].

To examine cytokines release related to cardiopulmonary bypass(CPB), the anthers investigated the possible differences in cytokines responses between patients undergoing prosthetic valve replacement (study group, n = 10) and those receiving closure of patent ductus arteriosus or pericardiectomy(control group, n = 9). Venous levels of interleukin-2 (IL-2), soluble interleukin-2 receptor (sIL-2R), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and interleukin-10 (IL-10) were measured at multiple time points before, during and after operation. As compared with pre-operative values, IL-2 levels in both groups decreased significantly (P < 0.05), and the levels of sIL-2R, IL-6, TNF-alpha, and IL-10 in both groups increased significantly at multiple time points post-operative (P < 0.01). All the values of cytokines returned to pre-operative levels at 7th post-operative day. Although there were no pre-operative differences in these cytokines between the two groups (P > 0.05), the post-operative changes of cytokines in study group was more obvious than that in control group (P < 0.01). In study group IL-10 rose to a peak value of around 620 pg/ml at the end of CPB while IL-6 and TNF-alpha levels reached their peak values of around 88 pg/ml and 52 pg/ml respectively at 1st post-operative day. IL-10 has been reported as an antiinflammatory cytokine. The preceding IL-10 peak value, as compared with the peak values of IL-6 and TNF-alpha, could be associated with the interplay and regulation of cytokine network. On the other hand, in control group the levels of IL-6, TNF-alpha, and IL-10 reached their peak values at 1st post-operative day simultaneously. The values were 34 pg/ml, 36 pg/ml, and 162 pg/ml respectively. This result suggests that besides surgical stress mediated cytokines production or suppression, CPB itself also results in obvious changes of cytokine metabolism. However further studies are needed to elucidate the underlying mechanisms and clinical value of post-operative cytokines production or suppression related to CPB in patients with prosthetic valve replacement.

Adult↗

PubMed1998

[HA-coated titanium implants used as orthodontic anchorage. An experimental investigation of implant stability and peri-implant neck tissue in dogs].

This study was aimed at the feasibility of using HA-coated titanium endosseous implants as orthodontic anchorage. These implants installed in dog's mandibles were loaded with the orthodontic force of 150 g for 3 months. The stability of the implant and the peri-implant neck tissue were investigated with radiograph and index evaluation. The findings demonstrated that no implant was mobile or loose or dislocated. The soft tissue around the cervical part of the implants had a slight inflammation because of bad oral hygiene and the stimulation of residual food attached to the stainless string. However, no resorption of marginal alveolor bone was found under sustained orthodontic force. The above results suggest that the HA-coated titianium implant can be used as anchorage for short-term orthodontic treatment.

Animals↗

PubMed1998

[PAH-DNA adduct in human lung cancer explants. A preliminary study].

OBJECTIVE: To study the influences of external exposure on polycyclic aromatic hydrocarbons (PAH)-DNA adduct formation in lung cancer patients. METHODS: On the basis of pilot experiments in mice, 32P post-labeling assay developed by Randerath was used to measure PAH-DNA adduct in human lung tissue explants. Relative adduct label(RAL) value was employed as a measure of adduct formation. A case-control study was designed using age-, sex-, and residence-matched patients with lung cancer and benign pulmonary diseases. RESULTS: Although the mean RAL value in male lung cancer patients was not significantly different from that in patients with benign diseases, patients who smoked cigarettes had significantly higher RAL value than those who did not smoke(27.62 x 10(-9) versus 11.42 x 10(-9), P = 0.0015). In contrast, in female lung cancer patients, the RAL value was significantly higher in patients with lung cancer than in those with benign lung diseases (13.59 x 10(-9) versus 7.9 x 10(-9), P < 0.05). Moreover, significant difference in RAL values existed between female smokers and non-smokers. Cooking affected female patients only. Higher RAL values were seen in patients with squamous-cell carcinoma than with adenocarcinoma (P < 0.05). RAL values were significantly higher in poorly differentiated than in well-differentiated lung cancers (P < 0.05). A significant increase in RAL values was observed in patients with lymph node metastasis as compared with those without lymph node metastasis. CONCLUSION: PAH-DNA adduct level in lung tissue explants can be taken as a measure of environmental exposure and it correlates with the histological type, degree of differentiation and lymph node metastasis of lung cancer.

Adenocarcinoma↗

PubMed1998

[Significance and correlation of T lymphocyte subgroup, erythrocyte immune function and argyrophilic protein in nucleolar organizer regions in tuberculosis patients].

OBJECTIVE: To study the significance and relationship of T lymphocyte subgroups, erythrocyte immune functions and argyrophilic protein in nucleolar organizer regions (AgNORs) in tuberculosis patients. METHOD: CD3+, CD4+, CD3+/CD4+ were determined using alkaline phosphatase-antialkaline phosphatase (APAAP) method, E-C3bRR and E-ICR were assayed by observing receptor rate. Granules area of AgNORs (GA) and nuclear area (NA) were studied by image analysis system. RESULT: CD3+, CD4+, CD4+/CD8+, E-C3bRR, GA/NA in tuberculosis patients were significantly lower than those in the healthy group (P < 0.001). However, the values of E-ICR, CD8+ were significantly higher than those of control group (P < 0.001). CONCLUSION: The results of T lymphocyte subgroup, erythrocyte functions and AgNORs are in accord, and might be usefull in assessing diagnosis and prognosis of tuberculosis.

Adult↗

PubMed1998

[Clinical study of puerarin in treatment of patients with unstable angina].

OBJECTIVE: To observe the clinical efficacy of puerarin in treating patients with unstable angina (UA). METHODS: Frequency of angina events, consumed doses of nitrates, heart rate, blood pressure, rest electrocardiogram (ECG) and myocardial oxygen consumption were observed before and after drug therapy in puerarin group (21 cases) and control group (18 cases) respectively. RESULTS: The puerarin group not only showed more effective than that in control group in reducing frequency of angina events and consumed doses of nitrates and improving abnormal rest ECG, but also appeared to be preferable to the control group in reducing myocardial oxygen consumption and increasing exercise duration (P < 0.05). CONCLUSION: Puerarin is a safe and effective drug in treating patients with UA.

Aged↗

PubMed1998

[Investigation of the clinical value of total salival flow rates].

OBJECTIVE: To investigate clinical value of total saliva flow rates. METHODS: The symptom of dry mouth was correlated with unstimulated (UWSFR) and stimulated (SWSFR) whole saliva flow rates on chewing medical paraffin in 62 patients with dry mouth complaints (30 with Sjögren's syndrome, 32 with sialosis) and 23 controls. The symptom of dry mouth was classified into 0,1,2,3,4 according to a treatment emergent symptom scale (TESS). UWSFR and SWSFR were determined after fasting in the morning. RESULTS: UWSFR was (0.070 +/- 0.089) ml/min in Sjögren's syndrome, (0.175 +/- 0.115) ml/min in sialosis, (0.330 +/- 0.188) ml/min in controls. SWSFR was (0.709 +/- 0.720) ml/min in Sjögren's syndrome, (1.561 +/- 0.867) ml/min in sialosis, (1.894 +/- 0.661) ml/min in controls. A highly significant correlation was found between TESS score and UWSFR and between TESS score and SWSFR. Only UWSFR was decreased in the patients with a TESS score of 1 or 2, while both UWSFR and SWSFR were significantly decreased in patients with TESS scores of 3,4. CONCLUSION: It is concluded that UWSFR is more sensitive in relation to dry mouth complaints than SWSFR, and that a mild dry mouth is mainly related to decreased UWSFR.

Adult↗

PubMed1998

[Endovascular exclusion of abdominal aortic aneurysm].

OBJECTIVE: To explore the indications, methods, manipulations, and problems of endovascular exclusion of abdominal aortic aneurysm (AAA). METHOD: Under general anesthesia and dynamic supervision of DSA, an endovascular exclusion with a stent-graft complex of 11.0 cm x 2.6 cm was successfully performed on a 70-year-old man contraindicated for major open surgery with AAA of 10.0 cm x 6.0 cm and an AAA neck of 2.5 cm x 1.6 cm. RESULT: The patient was up and about on the first postoperative day. Duplex scan (by the end of the first postoperative week) and CT (on the postoperative 20th day) revealed a completely excluded AAA by the stent-graft that was patent and had an inner diameter of 2.2-2.4 cm, without migration and torsion. The primary AAA sac was full of thrombi and no patent lumbar and inferior mesenteric arteries were observed. The external diameter of AAA was unchanged, renal and iliac arteries were all patent, but a micro-crevice between the proximal end of the stent-graft and the anterior wall of the AAA neck was revealed. Six months postoperative follow-up showed that the patient's abdominal pulsatile mass and the left lower extremity's claudication disappeared. CONCLUSION: Endovascular exclusion of AAA is of great practical value.

Aged↗

PubMed1998

[PCR-based detection of HLA-DQ alpha and polymarker loci and their application in forensic science].

Studies were conducted to evaluate the forensic applicability of multiplex amplification of HLA-DQ alpha and PM loci. These loci could be simultaneously typed by reverse dot blot approach where allele specific oligonucleotide probes were immobilized on a nylon membrane strip. Allele and genotype frequencies for HLA-DQ alpha and PM loci were determined in Chinese Han population. The frequency data can be used in individual identification and paternity test.

Female↗

PubMed1998

[Study on the interaction of Et2SnCl2(phen) with DNA].

The absorbance, fluorescence and cyclic voltammetric methods as well as agarose gel electrophoresis were used to study the interaction of the antitumor compound Et2SnCl2(phen) with DNA. The results indicate that Et2SnCl2 (phen) mainly reacts electrostatically with the phosphate backbone of DNA. There also exists an intercalation into the double-helix of DNA through the phenanthroline group of Et2SnCl2(phen). At high concentration Et2SnCl2(phen) can cause unwinding of DNA. The molecular action mechanism of Et2SnCl2(phen) with DNA was first proposed.

Animals↗

PubMed1998

[Stability of HA-coated titanium implants used as orthodontic anchorage].

12 two-stage HA-coated titanium implants were inserted into the mandibular alveolar bones of two dogs were loaded with orthodontic force of 150 gram for 3 months. The stability of the implants under orthodontic force were studied with intraoral and radiographic examinations. The results showed that both intraoral and radiographic analysis were reliable for assessing implant stability, and no signs of fixture dislocation were found during the force application period (P > 0.05), while the abutment was tilted after being loaded for 2 to 3 months. This suggests that HA-coated titanium implants remain stable enough under orthodontic force and are suitable as anchorage for short-term orthodontic therapy after design of the implant neck is improved.

Animals↗

PubMed1998

[New application of atomic absorption spectrophotometer in testing technology].

A simple and satisfactory method is developed for the new application of AAS. We can just rely on atomic absorption spectrophotometer without flame on place of UV-Visible spectrophotometer. The operation is very simple, and it can raise the efficiency of AAS. This experiment offers a possibility to find new applications of atomic absorption spectrophotometer.

English Abstract↗

PubMed1998

[Determination of the content of serum calcium with methylthymol blue as chromogenic reagent].

It is reported in this paper that calcium can be determined with MTB as chromogenic reagent by isoabsorption dual-wavelength elimination. The measuring wavelength and referential wavelength were 613.7 and 590.0nm, respectively. No masking reagent was necessary in the analysis. The average recovery and RSD of calcium are 98.98% and 0.81%, respectively. Compared with titration, this method is rapid, simple and precise.

Absorption↗

PubMed1998

Microsomal metabolism of delavirdine: evidence for mechanism-based inactivation of human cytochrome P450 3A.

Administration of delavirdine, an HIV-1 reverse transcriptase inhibitor, to rats or monkeys resulted in apparent loss of hepatic microsomal CYP3A and delavirdine desalkylation activity. Human CYP3A catalyzes the formation of desalkyl delavirdine and 6'-hydroxy delavirdine, an unstable metabolite, while CYP2D6 catalyzes only desalkyl delavirdine. CYP2D6 catalyzed desalkyl delavirdine formation was linear with time (up to 30 min) but when catalyzed by cDNA expressed CYP3A4 or human liver microsomes the reaction rate declined progressively with time. Coincubation with triazolam showed that delavirdine caused a time- and NADPH-dependent loss of CYP3A4 activity in human liver microsomes as measured by triazolam 1'-hydroxylation. The catalytic activity loss was saturable and was characterized by a Ki of 21.6 +/- 8.9 microM and a kinact of 0.59 +/- 0.08 min-1. An apparent partition ratio of 41 was determined with cDNA expressed CYP3A4, based on the substrate depletion method. Incubation of [14C]delavirdine with microsomes from several species resulted in irreversible association with an approximately 50 kDa protein, as demonstrated by SDS-PAGE/autoradiography. Binding to the protein was NADPH dependent, glutathione insensitive, proportional to the level of CYP3A expression and was inhibited by ketoconazole, a specific CYP3A inhibitor. NADPH-dependent irreversible binding to human and rat total microsomal protein was demonstrated following exhaustive extraction of microsomal protein. Binding was decreased in the presence of glutathione and appeared to be related to expression level of CYP3A. These results suggest that delavirdine can inactivate CYP3A and has the potential to slow the metabolism of coadministered CYP3A substrates.

Animals↗

PubMed1997

Effects of adenovirus-mediated human apo A-I gene transfer on neointima formation after endothelial denudation in apo E-deficient mice.

BACKGROUND: Inactivation of apolipoprotein (apo) E genes in mice markedly increases beta-VLDL levels and accelerates progression of complex atherosclerotic lesions. The present study investigated (1) the effect of apo E deficiency (apo E-/-) on neointima formation after endothelial denudation; and (2) the effect of increased HDL, induced by adenovirus-mediated transfer of a human apo A-I gene, on neointima formation. METHODS AND RESULTS: Guidewire-induced abrasion of the endothelium of the common carotid artery did not produce neointima formation within 18 days after injury in C57BL/6J mice (n=12) but was associated with an intima/media ratio of 0.82+/-0.25 in age-matched C57BL/6J apo E-/- mice (n=12). Neointima consisted primarily of smooth muscle alpha-actin positive cells. Injection in C57BL/6J apo E-/- mice of 2x10(9) (n=5) or 4x10(9) (n=7) plaque forming units (p.f.u.) of a recombinant human apo A-I adenovirus 3 days before injury resulted in an increase of HDL cholesterol from 36+/-5 to 75+/-3 mg/dL (P<.05) and to 96+/-13 mg/dL (P<.05), respectively, and of the HDL cholesterol/non-HDL cholesterol ratio from 0.063+/-0.003 to 0.15+/-0.01 (P<.05) and to 0.16+/-0.015 (P<.05), respectively. Intima/media ratio decreased to 0.28+/-0.06 (P=NS versus C57BL/6J apo E-/- mice) with 2x10(9) p.f.u. of apo A-I virus and to 0.03+/-0.01 with 4x10(9) p.f.u. (P<.01 versus C57BL/6J apo E-/- mice). Injection of 4x10(9) p.f.u. of RR5 (n=7) or tissue plasminogen activator (t-PA) control virus (n=6) did not result in a significant alteration of HDL cholesterol (44+/-11 and 26+/-4 mg/dL, respectively) nor in a reduction of intima/media ratio (0.81+/-0.35 and 0.86+/-0.23, respectively). CONCLUSIONS: Apo E deficiency is associated with increased neointima formation after endothelial denudation. Gene transfer of apo A-I increases HDL cholesterol and significantly reduces neointima formation, which suggests a direct vascular protective effect of HDL.

Adenoviridae↗

PubMed1997

Contribution of serum protein association to discrepancy between the in vivo and in vitro UDS results for 6,7-dimethyl-2,4-di-1-pyrrolidinyl-7H-pyrrolo[2,3-d]pyrimidine (U-89843).

U-89843 has been shown to undergo biotransformation, both in vitro and in vivo, to form U-97924 as a major primary metabolite. U-89843 was found to be positive in an in vitro UDS mutagenesis screen conducted with primary rat hepatocytes in serum-free media. In contrast to in vitro results, no evidence of genetic toxicity of U-89843 was observed in rats in the in vivo/in vitro version of the UDS test with single oral doses up to 1400 mg/kg. The negative results may be related to more robust in vivo detoxification mechanisms or relatively lower exposure to reactive metabolites formed by bioactivation of U-89843 as compared to that observed in the serum-free in vitro hepatocyte test system. Further studies showed rat serum suppressed the in vitro metabolism of U-89843 as well as the formation of the corresponding hydroxylated metabolite, U-97924, the putative precursor of proposed reactive electrophilic metabolite. The measured in vivo systemic clearance of U-89843 (0.53 l/h/kg) in rats was about 1000-fold slower than the in vitro intrinsic clearance (606 l/h/kg) estimated by measuring the formation of U-97924 in rat liver microsomal incubations. Since U-89843 is extensively associated with serum proteins a poor extraction ratio into the liver may account for the slower biotransformation of U-89843 in vivo as compared to that exhibited in in vitro serum-free hepatocyte incubations. Addition of bovine serum albumin (1-40 mg/ml) to the in vitro UDS assay medium decreased the UDS mean net grains per nucleus response of U-89843. These results suggest that the effect of serum protein should be considered when comparing serum-free in vitro UDS and in vivo UDS results for highly serum protein bound compounds.

Animals↗

PubMed1997

Reduced glutathione prevents nitric oxide-induced apoptosis in vascular smooth muscle cells.

The control of medial and neointimal growth, in which vascular smooth muscle (VSM) plays a central role, is most important to the development of hypertension and atherosclerosis, respectively. Growth of vascular smooth muscle cells is regulated by a number of factors, including the vasodilator nitric oxide (NO). In addition, NO modulates intracellular thiol redox states and the thiol redox state of the cell influences NO production. We, therefore, examined the nature of the effect of NO on growth of VSM cells and its modulation by cellular glutathione content. Here, we report that NO, either generated by NO donors or synthesized by iNOS in VSM cells, inhibited DNA synthesis and induced apoptosis in this cell type. NO-induced apoptosis was associated with a significant decrease in the intracellular concentration of reduced glutathione and with an increase in the level of the tumor suppressor gene p53 mRNA. Moreover, addition of glutathione monoethylester to the culture restored the level of reduced glutathione in VSM cells, and prevented the NO-induced increase in p53 expression and programmed cell death. Our findings suggest a role for reduced glutathione in protecting VSM cells exposed to NO from apoptosis.

Animals↗

PubMed1997

Positive effects of SH2 domain-containing tyrosine phosphatase SHP-1 on epidermal growth factor- and interferon-gamma-stimulated activation of STAT transcription factors in HeLa cells.

SHP-1 (also known as PTP1C, SHPTP-1, SHP, and HCP) is an SH2 domain-containing protein-tyrosine phosphatase. We have stably overexpressed the native form and a catalytically inactive cysteine to serine mutant of the enzyme, SHP-1-(Cys --> Ser), in human cervical carcinoma HeLa cells. Following stimulation of the cells with epidermal growth factor (EGF) and interferon-gamma (INF-gamma), signal transducers and activators of transcription (STAT) activity was analyzed by using two 32P-labeled DNA probes, namely hSIE which is derived from a high affinity mutant form of the serum-inducible element in the c-fos promotor and GAS which resembles the INF-gamma activation site. EGF induced hSIE binding activity only, and the activity was suppressed by approximately 70% when the inactive mutant form of SHP-1 was expressed but was essentially unaffected by expression of the native enzyme. INF-gamma treatment resulted in appearance of both hSIE and GAS binding activities. While expression of the inactive mutant reduced the activities by 30-50%, the native enzyme caused a 20-30% increase. Consistent with effects on STAT activation, altered SHP-1 expression also affected EGF-induced activation of the mitogen-activated protein kinase pathway; expression of SHP-1-(Cys --> Ser) inhibited activity of MEK by approximately 25%, whereas expression of SHP-1 resulted in a approximately 25% increase. Further studies revealed that overexpression of SHP-1 caused decreased tyrosine phosphorylation of the EGF receptor and that EGF induced phosphorylation and recruitment of SHP-1. Together, the data suggest that SHP-1 is positively involved in EGF- and INF-gamma-induced STAT activation in non-hematopoietic HeLa cells and that, in the EGF signaling system, SHP-1 functions at least partly by modulating tyrosine phosphorylation of EGF receptor.

Enzyme Activation↗