Biomedical subjects

Y Zhao

Publications and source records attributed to Y Zhao.

At least 379 records · Page 21Linked to original sources

PubMed2000

[Preclinical study of preimplantation genetic diagnosis in animal].

OBJECTIVE: To perform preimplantation genetic diagnosis (PGD) in transgenic mice. METHODS: Single blastomere from murine heterozygous pre-embryo at 4 or 8-cell stage was sampled by microbiopsy for detection of the human gene delta F508 mutation of cystic fibrosis and biopsied pre-embryo was transferred to Swiss mice foster mothers. delta F508 mutation detection on the single blastomere was performed with nested polymerase chain reaction(PCR). RESULTS: (1) Significant difference was not observed statistically for the in vitro hatching rate (n = 102), the birth rate (n = 79), birth weight and organ weight (n = 133) at 3 weeks after births between mice born from biopsied embryos and controls. (2) Thirty-two nested PCR were performed for the diagnosis of the cystic fibrosis delta F508 mutation, with 100.0% specificity and 100.0% sensitivity. CONCLUSIONS: Microbiopsy of pre-embryos with 4 or 8-cells did not alter their viability and further development. The technique of nested PCR on a single blastomere for the detection of cystic fibrosis delta F508 mutation is reliable.

Animals↗

PubMed2000

[Effect of lost bite force on the expression of bFGF in rat molar periodontal ligament].

OBJECTIVE: To observe the dynamic change of the expression of basic fibroblast growth factor (bFGF) in rat molar periodontal ligament(PDL), combined with other experiments to probe into the relation of the expression between bFGF and type I collagen mRNA. METHODS: Animal model was established by extracting the left maxillary molars. Immunohistochemistry was applied. RESULTS: The expression of bFGF obviously increased from the first day to the second week (P < 0.05), Came back to that of normal bite force group at the third week. There were strong negative relative relationship between the expression of bFGF and that of type I collagen mRNA. CONCLUSION: The expression of bFGF increased under lost bite force in rat molar PDL. The effect of bite force on the expression of PDL type I collagen mRNA is closely related to the expression of bFGF.

Animals↗

PubMed2000

[Comparative study of technique of laser welding ceramo-alloy by different gap distance].

OBJECTIVE: To investigate the quality of laser welded non-precious base alloy by different gap distance and its clinic probability. METHODS: Laser welded ceramo-alloy CW-PA specimens by different gap distance of 0.0 mm, 0.25 mm, 0.5 mm, Tested joined sample's UTS, microhardness; took SEM examination on its tensile fracture surface and metallographic examination on longitudinal cross section. RESULTS: The study showed that UTS of Laser welded CW-PA by different gap distance of 0.0 mm, 0.25 mm, 0.5 mm is (446.05 +/- 82.50) MPa, (485.97 +/- 62.35) Mpa, (503.32 +/- 65.79) MPa respectively, approach to original rod (421.53 +/- 21.78) MPa (P > 0.05). Microimage at tested samples of gap distance at 0.0 mm, 0.25 mm are good. CONCLUSION: It revealed that 1. Laser welding specimen should be contacted as close as possible 2. The gap distance should be less than 0.5 mm, 0.25 mm is better, and easy to handle.

Dental Soldering↗

PubMed2000

[Digital dental radiographic technique and its clinical application].

OBJECTIVE: To investigate the digital dental radiographic technique and its clinical application. METHODS: One hundred and five dental films were taken in 88 cases with the digora digital radiographic system and studied. RESULTS: The digora system has more advantages than the conventional dental radiographic technique. The image plate was used instead of the films and shorten exposure time. It had high exposure tolerances and image processing functions. CONCLUSIONS: This new imaging system applied in the clinics and research work can play an important role in improving the diagnostics.

Humans↗

PubMed2000

[The role of MHC molecules on OSCC cells in the induction of autologous cytotoxic T lymphocytes].

OBJECTIVE: To investigate the role of major histocompatibility complex(MHC) molecules in the induction of cytotoxic T lymphocyte(CTL) from oral squamous cell carcinoma. METHODS: 1. The treated autologous tumor cells served as stimulating cells, on which the MHC mAb was used to block the HLA-ABC and/or HLA-DR antigens. The specific cytotoxicity of CTL induced by stimulating cells and the level of released TNF-alpha were then detected. 2. By blocking the HLA-ABC and/or HLA-DR antigens on target cells, the inhibition effect of MHC mAb on CTL cytotoxicity induced by autologous stimulating cells (not treated with mAb) was measured. RESULTS: 1. The cytotoxicity induced by stimulating cells in experimental groups was significantly lower than that of the control group. The successive order was: the DR antigen positive stimulating cell group > ABC antigen positive stimulating cell group > both ABC and DR antigen negative stimulating cell group. The specific TNF-alpha released by CTL was completely blocked by anti-ABC mAb. 2. The average inhibition rate by mAb on cytotoxicity of CTL was: 52%, 27% and 72% by anti-ABC mAb, anti-DR mAb, and anti-ABC mAb plus anti-DR mAb respectively. CONCLUSION: Both MHC-class I and class II antigens on OSCC cells play an important role in inducing CTL.

Adult↗

PubMed2000

[Further survey on efficacy of attenuated live hepatitis A vaccines].

OBJECTIVE: To further survey the protective efficacy of the standard attenuated live hepatitis A vaccines (H(2) strain). METHODS: Randomized and controlled trials were performed in Fucheng county, Hebei province. A total of 12 036 children were assigned into vaccine group (5 551) and control group (6 485) by cluster sampling. The morbidity of hepatitis A was observed and the blood was collected once hepatitis A showed epidemic to detect anti-HAV IgG and IgM. RESULTS: During the period of the first 7 months after vaccination, hepatitis A was sporadic, the morbidity of hepatitis A was 0.55/100 000, and only 1 case occurred in the control group and no case in the vaccine group. From January to August 1998, hepatitis A showed epidemic in a township of this county. The morbidities were 0.37% and 6.69% for vaccine group and control group, respectively. The protective efficacy of the vaccine was 94.47%. The ratios of clinical cases to subclinical infections were 1 to 11 and 1 to 1 for vaccine and control groups, respectively (P < 0.05). CONCLUSION: The H(2) strain vaccine has a very good protective efficacy, and obviously decreases the attack rate, new infection rate and clinical cases by HAV infection.

Child↗

PubMed2000

[Clinical study on ultra-early intravenous thrombolysis with high-dose urokinase in treatment of acute cerebral infarction].

OBJECTIVE: To determine the clinical curative effect and safety of ultra-early intravenous thrombolysis with high-dose urokinase in treatment of acute cerebral infarction. METHODS: Thirty-one patients with atherosclerotic cerebral infarction were treated with a single dose of 1.5 x 10(4) U/kg urokinase as intravenous thrombolytic therapy within 6 h after the onset. The decrease degree of nerve function defect integral, the cure rate, the effectual rate, and the total effective rate were observed 3 h and 21 days after thrombolysis, respectively, and the results were compared with those of conventional treatment. The infarct volume of patients treated with the two therapies were compared 21 days after treatment. RESULTS: The nerve function defect integral examined 3 h after thrombolysis (14.2 +/- 2.1) was markedly lower than that before thrombolysis (26.5 +/- 9.1). A remarkable difference (n = 31, t = 4.669, P < 0.05) was noticed between them. The cure rate and effectual rate reached 22.58% (7/31) and 67.74% (21/31), respectively. The decrease degree of nerve function defect integral, the cure rate, the effectual rate and the total effective rate evaluated 21 days after thrombolysis were all higher than those of conventional therapy group (from 26.5 +/- 9.1 to 8.8 +/- 2.8 vs from 26.4 +/- 8.1 to 16.3 +/- 4.1, t = 2.417; 51.61% vs 15. 38%, chi(2) = 5.037; 70.96% vs 42.30%, chi(2) = 4.765; 87.09% vs 65.38%, chi(2) = 3.886, respectively; all P < 0.05). The infarct volume was markedly smaller than that of the conventional therapy group (3.7 cm 3 +/- 3.0 cm(3) vs 5.3 cm(3) +/- 3.1 cm(3), t = 2.165, P < 0.05). CONCLUSION: Ultra-early intravenous thrombolysis with a single dose of 1.5x10(4) U/kg urokinase in the treatment of atherosclerotic cerebral infarction has a better clinical curative effect and less complication, and it can also have the infarct volume markedly reduced.

Cerebral Infarction↗

PubMed2000

[Study on the in vitro cleavage abilities of ribozymes specific to different sites of bcr-abl fusion gene and their induction of apoptosis in K562 cells].

OBJECTIVE: To investigate the in vitro cleavage abilities of ribozymes specific to different sites of bcr-abl fusion gene and their effects on K562 cell. METHODS: First, three single-ribozymes specific to the fusion point were designed. After recombination, 6 vectors including single-, double- and triple- ribozymes were constructed and their in vitro cleavage abilities were compared. Then the triple-unit ribozyme retroviral vector was transfected into K562 cell to test its effect on cell cycle, apoptosis and cell structure. RESULTS: These ribozymes can cleave the template in vitro with different efficiency. The triple-unit ribozyme, with an efficiency of 70.8%, was the most efficient one. The cleavage efficiency of single-unit RZ1, RZ2 and RZ3 was 54.6%, 25.3% and 3.6%, respectively. Those of double-unit RZ12 and RZ23 were 60.7% and 30.3% respectively. The triple-unit ribozyme could inhibit the K562 cell growth by inducing apoptosis. CONCLUSION: It is a new way to treat CML by ribozymes specific to bcr-abl fusion gene, which made it available to purge bone marrow by bcr-abl specific ribozymes.

Apoptosis↗

PubMed2000

[Effect of radiotherapy on penetration of 5-FU in blood-pancreatic barrier in rats].

OBJECTIVE: To investigate the effect of radiotherapy dose on penetration of 5-FU (5-fluorouracil) in blood-pancreatic barrier in rats. METHODS: After the pancreatic region of the rats were irradiated by 2, 10, 20, 30 and 40 (Gy) doses of gamma-ray, we investigated the penetration ratio (PR) of 5-FU in the pancreatic tissue with HPLC assay. RESULTS: When treated with low-dose of gamma-ray (2 Gy), the PR of 5-FU increased obviously after 8 hours. But in the high-dose groups (>/= 10 Gy), the PR was less than or had no difference with control group. At the same time, we found that the islets had appeared pathological degeneration, while the pancreatic lobular structure, acini and ducts had no visible changes in 20 Gy group. CONCLUSIONS: After the treatment of low-dose of gamma-ray combined with 5-FU, the effect of chemoradiotherapy may be improved for enhanced PR of 5-FU in pancreatic tissue, and at the same time, chemotherapy and radiotherapy cooperate with each other. But in high dose groups (>/= 10 Gy), radiotherapy may reduce the effect of chemotherapy in acute phase. After high-dose radiotherapy, we should pay attention to the change of glucose-resistance of patient to reduce the incidence of radiotherapy complication.

Animals↗

PubMed2000

[An electron microscopic histochemical study on the fibrous formation in pleomorphic adenoma of the salivary gland].

OBJECTIVE: To study the kinds of fibers and mechanism of fibrous formation in myxochondroid tissue of pleomorphic adenoma. METHODS: Eight cases of pleomorphic adenomas of salivary gland were studied by histological and electron microscopic histochemical techniques. RESULTS: The histological study showed that collagenous fibers and elastic fibers which constituted the trestle were distributed in myxochondroid areas of pleomorphic adenoma. The electron microscopic histochemical study showed that the myxochondroid tissue contained slender collagen fibrils measuring 50 nm in diameter and heavily stained elastic fibers. In cytoplasm of the myxochondroid cells two types of the Golgi-derived vesicles were seen: one was small round vesicles with a uniform electron dense core of amorphous material and heavily stained; another type was small round vesicles with a non-uniform electron dense core of filamentous material and stained grey. These materials were released into the extracellular space by cytoplasmic exocytosis. CONCLUSIONS: Neoplastic myoepithelial cells have the ability to synthesize and secrete procollagen and precursor of elastin, thus forming collagenous fibers and elastic fibers in myxochondroid areas.

Adenoma, Pleomorphic↗

PubMed2000

Pancreatic insulinomas: experience in 220 patients.

OBJECTIVE: To summarize the experience in the diagnosis and treatment of insulinoma. METHODS: We retrospectively reviewed 220 patients with insulinoma confirmed surgically in the PUMC Hospital from 1953 to 1999. They were 131 men and 89 women, aged on average 39 years. RESULTS: In the 220 patients, the average interval from the onset of symptoms to diagnosis was 35 months. 54% of the patients were misdiagnosed before admission to the hospital. In 214 patients underwent operation, 201 (93.9%) had benign tumor and 12 (5.6%) malignant one. The diameter of 78% tumors was less than 2cm. 90.7% tumors were single and 9.3% were multiple. 37.1% tumors were located in the head and uncinate process of the pancreas, 26.1% in the body, 36.1% in the tail, and 0.7% ectopic. 95.5% patients had Whipple's triad and the ratio of insulin to glucose was greater than 0.3 in 89% patients. The positive rates of B-ultrasound, CT and MRI for localization before operation were low, but those of angiography and PTPC were 62.8% and 88% respectively. Most patients could be cured by simple enucleation of tumor. The main complications were pancreatic fistulae and pancreatitis. CONCLUSION: It is important for surgeons to familiarize with insulinoma, the most common islet cell tumor, for a better treatment.

Adult↗

PubMed2000

[Photodynamic therapy of hematoporphyrin derivative on human pancreatic carcinoma cell lines].

OBJECTIVE: To observe the effect of photodynamic therapy (PDT) on human pancreatic carcinoma cell lines in vitro. METHODS: Two lines of human pancreatic carcinoma cell P3 and SW1990 were studied to investigate the killing role of PDT with hematoporphyrin derivative (HPD) as photosensitizer and sodium lamp as light source. The cultured cells were treated with serial concentrations of HPD followed by irradiation of different dosages of visible light, then MTT colorimetric assay was applied to measure the relative inhibitory rate of PDT for the cells. RESULTS: The relative inhibitory rate of PDT for the cells elevated along with the increase in the concentration of sensitizer and dose of light. Under the low photodynamic dose, it increased rapidly, and gradually slowed down to reach the plateau. Under the same photodynamic dose, significant difference in the inhibitory rate between the two lines was observed (P < 0.01), and the LD90 was also different. CONCLUSIONS: PDT has a significant killing effect on human pancreatic carcinoma cell lines in vitro, and its relative inhibitory rate appears to be correlated with the dose of sensitizer and light irradiation. The sensitivity of the two cell lines to PDT is different.

Cell Line, Tumor↗

PubMed2000

[Staple in pericardial devascularization of upper GI bleeding due to portal hypertension: application and therapeutic effect].

OBJECTIVE: To investigate the therapeutic effect of staple in pericardial devascularization on upper GI bleeding due to portal hypertension. METHODS: From July, 1997 to July, 2000, 30 portal hypertensive patients were treated by using pericardial devascularization plus partial resection of lower part of the esophagus with staple (CDH25). The eliminating rate of varicose veins of the lower part of the esophagus and the stenosis rate of anastomosis were evaluated. The therapeutic effect of pericardial devascularization without lower part esophageal resection in 28 patient with upper GI bleeding due to portal hypertension was taken as control. RESULTS: All the patients were followed up for 23 months. There was no death due to the operation. All patients in the study group had no upper GI rebleeding during the 23-month follow-up. The rebleeding rate in the control group was 18% (5/28) (P < 0.05 vs. Study group). The varicose veins eliminating rate was 100% in the study group and 53.6% (15/28) in the control group (P < 0.01); the stenosis rate of anastomosis was 6.7% (2/30) in the study group. CONCLUSION: The therapeutic effect of pericardial devascularization could be improved by the use of staple with shorter operative time.

Adult↗

PubMed2000

[Protective efficacy of H2 strain live attenuated hepatitis A vaccines in an outbreak of hepatitis A].

OBJECTIVE: To investigate the protective efficacy of H(2) strain live attenuated hepatitis A vaccine (H(2)-strain vaccine) locally produced in an outbreak of hepatitis A (HA). METHODS: A nonrandomized controlled design was used in a trial for HA vaccination. Five thousand five hundred and fifty-one children at preschool classes and at grades 1 - 3 of primary schools were selected in 14 villages. Epidemiological and serological methods were used to evaluate its protective efficacy of the vaccines and serum immunoglobulin M against hepatitis A virus (IgM anti-HAV) was detected with ELISA for 271 subjects in vaccinated group and 341 in the control one. RESULTS: An outbreak of HA occurred one year after the vaccination with 26 cases in the vaccinated group, including one vaccine-related case with an attack rate of 0.28% (1/356), and 25 cases in the control group with an attack rate of 5.92% (25/422). The protective efficacy of vaccines was 95.27% (95% confidence interval of 85.83% to 104.72%). Positivity of IgM anti-HAV, i.e., newly-infected cases, was 4.43% (12/271) in the vaccinated group and 13.38% (42/314) in the control group, respectively. Clinically apparent cases accounted for 8.33% (1/12) and 50.00% (21/42) in newly-infected cases in vaccinated and control groups, respectively. CONCLUSION: Vaccination with H(2) strain vaccines locally produced was effective in reducing occurrence of HA during its outbreak, but not so effective in preventing its infection. A booster dose of HA vaccine should be vaccinated for children in adequate time.

Adolescent↗

PubMed2000

[The change in hyaluronic acid (HA) in auto-and allo-skin intermingled grafting in extensive full thickness burn in rat model].

OBJECTIVE: To elucidate the changes in hyaluronic acid (HA) contents in auto-and alloskin intermingled grafting. METHODS: HA was determined by radio-immunoassay in auto-and alloskin intermingled grafting (a large sheet of allograft inlaid with small stamps of autoskin) in experimental extensive full-thickness burn rats on 3rd, 5th, 7th, 14th, 21st, 28th postoperation days. RESULTS: In both areas of intermingled skin grafting, the contents of HA was reduced first and increased significantly thereafter, but the contents in auto-skin areas rose earlier and higher than those in allo-ones. CONCLUSION: The results suggest that adequate application of HA may be beneficial to the healing and remodelling of grafted area.

Animals↗

PubMed2000

[Three-dimensional finite element analysis of all-ceramic crowns of the posterior teeth].

The all-ceramic crown has been applied in clinical practice for its esthetic value and excellent biocompatibility. The purpose of this study was to examine the effect of different cervical marginal shapes on the stress distribution of all-ceramic crowns of the mandibular first molar by three-dimensional finite element analysis. The results showed that under vertical loading, the bearing compress stress on the occlusal region, the tensile stress concentration were observed at buccal cervical marginal of all-ceramic crowns; the stress at the surface of the crown was the highest, the stress inside the crown was higher than that inside the prepared teeth; the shoulder's stress value was lower than the chamfer's. These results lay the theoretic foundation for clinical application of all-ceramic crown, suggesting that the shoulder design should be recommended in clinical practice when the all-ceramic crowns are planned. The cervical thickness of the crown should be within 0.5-1.0 mm, and the crowns surface should be polished well to improve its resistance to fracture.

Ceramics↗

PubMed2000

[Protective effect of xinxin capsule on learning and memory impairment in mice].

OBJECTIVE: To investigate the effect of Xinxin Capsule on the scopolamine or ethanol induced impairment of learning and memory retention in mice. METHOD: Step-through and Morris Water-maze methods, wer used to the protective effect of Xinxin Capsule(0.4, 0.8, 1.6 g.kg-1, ig, 16 d) on the scopolamine or ethanol induced impairment of learning and memory retention in mice. RESULT: The Capsule(0.8, 1.6 g.kg-1, ig,) can turn over the Scope so as to induce the impairment of learning, and the Capsule((0.4, 0.8, 1.6 g.kg-1, ig) can improve the ethanol induced impairment of memory retention in mice. CONCLUSION: Xinxin Capsule helps regain as well as impair the learning and memory retention in mice.

Animals↗

PubMed2000

[Study of accuracy of one-piece casted and laser welded bridges].

OBJECTIVE: To assess whether laser welded bridge be fit for the clinical usage, this study compares the accuracy of laser welded multi-unit bridges with one-piece casted bridges. METHODS: A precise stainless mold which was 20 mm length composed of two abutments (one premolar and one molar) and one pontic (two missed teeth) was made. 5 wax patterns of four-unit FPD frame-works in one-piece casting based on the mold were made. After that, they were invested with inner (Bellavest) and outer investment (phosphate and gypsum). Then they were casted with CW-PA (Ni-Cr-Nb) alloys. The other 5 wax patterns of four-unit FPD frameworks were invested and casted in two halves. Each couple of frameworks were ultra-sonic washed in distilled water and inserted to the standard metal FPD mold accurately. Laser welding machine (DL-2002) was used to weld each couple of frameworks at 305V, 20 ms. Both groups of specimens were tested on their mesiodistal span dimensions and the diameters of alloy crowns. Then they were inserted to their original stainless mold, where the marginal fitness was examined. RESULTS: 1. The one-piece casted fixed multi-unit bridge couldn't be inserted to abutments completely because of distortion, while the laser welded bridge could be inserted to abutments completely. The average marginal opening of laser welded bridges was about 74 microns and conformed to clinical standard of fitness. 2. Mesiodistal dimensions of one-piece casted bridges at the inner, bottom and top margins were 19.5600 +/- 0.3877 mm, 41.2206 +/- 0.4140 mm, 41.0598 +/- 0.3379 mm respectively; while those of laser welded bridges were 20.2950 +/- 0.1191 mm, 41.9625 +/- 0.0788 mm, 42.0584 +/- 0.1089 mm, which were obviously close to metal abutments (P < 0.05). 3. The alloy crowns' diameters of one-piece casted bridges were examined as following, the premolar: phi IJ = 9.8386 +/- 0.0567 mm, phi LK = 9.9596 +/- 0.0548 mm, the molar: phi EF = 11.7948 +/- 0.0252 mm, phi HG = 11.9412 +/- 0.0763 mm; The alloy crowns' diameters of laser bridges were as following, the premolar: phi IJ = 9.7927 +/- 0.0636 mm, phi LK = 9.9438 +/- 0.0726 mm, the molar: phi EF = 11.8287 +/- 0.0863 mm, phi HG = 11.8893 +/- 0.1049 mm. There was no significant difference between the two groups (P < 0.05). CONCLUSION: Laser welding greatly improve the fitness of multi-unit fixed bridges.

Dental Abutments↗