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Biomedical subjects

Z Li

Publications and source records attributed to Z Li.

At least 811 records · Page 45Linked to original sources
PubMed1999

[Effects of environmental lead exposure in kindergartens on children's blood lead level].

OBJECTIVE: To determine if kindergartens' environmental status can influence children's lead exposure. METHODS: Environmental specimens, such as floor dust, peeled-off paint chip, soil and drinking water, as well as children's hand dust and blood samples, were collected and measured for their lead levels in 19 kindergartens, to analyze the relationship between children's blood lead levels and their environmental lead exposure. RESULTS: Geometric means of lead concentrations in indoor floor dust, peeled-off paint chip, dust fallout, outdoor floor dust, soil and drinking water were 86.5 microg/m(2), 235.5 microg/g, 445.9 microg/g, 172.4 microg/m(2), 70.1 microg/g and 12.5 microg/L, respectively. Lead level on children's hands averaged 3.4 microg at both hands. Blood lead levels in children correlated positively with the lead concentrations of outdoor floor dust and their hand dust, with correlation coefficients of 0.5186 and 0.2206, respectively. Multiple regression analysis showed that hand dust lead level in children entered the regression model with a largest standardized partial regression coefficient of 0.3842 and a coefficient of determination of 0.673 for the full equation with F = 6.52 and P < 0.01. CONCLUSION: Status of environmental health in kindergartens plays an important role in children's lead exposure. It is necessary to offer health education for children and make them wash their hands often and overcome unhealthy behavior of sucking their fingers.

Child Day Care Centers↗
PubMed1999

[Effects of lead exposure on their brain-stem auditory evoked potential in children].

OBJECTIVE: To determine if low lead exposure can influence auditory development in children. METHODS: Children were divided into two groups, i.e., low (< 0.483 micromol/L) and high (>or= 0.483 micromol/L) blood lead levels with atomic spectrophotometry (AAS). Latencies and latent intervals between peak waves of their brain-stem auditory evoked potentials (BAEP) in the two groups were measured and compared. RESULTS: There was positive correlation between blood lead levels and BAEP in wave III at right ear, wave V at both right and left ears and latent intervals between peak waves I to V, with correlation coefficients of 0.2991, 0.2748, 0.3248, 0.2064 and 0.2412, respectively. There was significant difference in latencies of wave III at right ear, wave V at both right and left ears and latent intervals between peak waves I to V at both right and left ears and those between waves of III to V at right ear in the low blood lead group. Latencies and latent intervals between peak waves were longer in the high blood level group (with a mean of 0.78 micromol/L and a range of 0.58 to 1.42 micromol/L) than those in the low one (with a mean of 0.30 micromol/L and a range of 0.17 to 0.45 micromol/L). CONCLUSION: Elevated blood lead level could cause prolongation of latencies and latent intervals between peak waves of BAEP and slowdown of the nerve conduction velocity, and so auditory development was influenced.

Child↗
PubMed1999

[Detection of Epstein-Barr virus, cell proliferation and apoptosis in thymic tumors].

OBJECTIVE: To investigate the incidence of thymic tumors in Guangzhou, its association with EBV infection and the cell proliferation and apoptosis characteristics of these tumors. METHODS: EBV encoded small RNAs (EBERs) were detected in 43 thymic tumors and 7 thymic hyperplasia samples by use of in situ hybridization, EBNA-1, LMP-1, PCNA, bcl-2 and p53 were examined using immunohistochemical methods, cell apoptosis was evaluated by TUNEL (TdT-mediated dUTP-X nick end labelling) in situ cell death detection kit. RESULTS: 1. Thymic diseases only accounted for 0.057% of biopsies in the Guangzhou area. Thymic tumor and hyperplasia accounted for 74.7% and 18.6% in thymic diseases respectively. Thymic lymphoepithelimoa-like carcinoma (LELC) occurred in 2.7% of thymic tumors. 2. EBV encoded products (EBERs, EBNA-1 and LMP-1) were not detected in 50 thymic disease specimens. 3. Marked proliferation (3+-4+) grade thymomas (0/18 cases) was much lower than that of thymic carcinomas (10/20 cases), and the marked apoptotic (2+-4+) grade was higher in thymomas (15/18) than the thymic carcinomas (13/20). 4. The p53 protein accumulation rate in thymic carcinomas (8/20) was significantly higher than that of thymomas (1/18). The apoptotic grade is significantly related to p53 accumulation in thymic epithelial tumors. 5. The bcl-2 over expression could be detected both in thymomas and thymic carcinomas. CONCLUSIONS: 1. Thymic diseases, including thymic LELC, is very rare in Guangzhou and is not closely associated with EBV infection. 2. Thymic carcinomas have a relatively rapid growth rate compared to thymomas. 3. p53 gene mutation may play an important role in the carcinogenesis of thymic carcinoma, and bcl-2 over-expression may also be involved in the evolution of thymic epithelial tumors. 4. Wild type p53 protein may exert an apoptosis-inducing function in thymic epithelial tumors, including thymomas and carcinomas, and a proliferation inhibiting function only in thymomas.

Adult↗
PubMed1999

[Effects of LMP-1 expression on neoplastic cell proliferation and apoptosis in nasopharyngeal carcinoma].

OBJECTIVE: To investigate the effects of LMP-1 expression on neoplastic cell proliferation and apoptosis in untreated nasopharyngeal carcinoma (NPC). METHODS: Biopsies from 55 untreated NPC cases were collected. EBERs was detected by in situ hybridization. PCNA, LMP-1 and bcl-2 were detected by immunohistochemistry method. Cell apoptosis was demonstrated by TUNEL (TdT-mediated dUTP-x nick end labeling) kit. RESULTS: (1) The positive LMP-(1) expression rate was 27/55 (49.1%). The median PI (PCNA Index) of LMP-1 positive cases (90.0%) was higher than that of LMP-1 negative cases (80.0%) and the p value was less than 0.05 by rank sum (rs) test. (2) The median TI (TUNEL Index) of LMP-1 positive cases (16.2 per high power field) was also higher than that of LMP-1 negative cases (10.4 per high power field) and the p value was less than 0.05 by rs test. (3) As for the bcl-2 expression percentages, no correlation was found between LMP-1 positive and negative cases. (4) A positive rank correlation existed between PI and TI (rs = 0.368 1, P < 0.01), but no correlation was found between TI and bcl-2 expression percentage. CONCLUSIONS: (1) NPC with LMP-1 expression have higher levels of PI, maybe resulting from the promotional effect of LMP-1 on cell proliferation. (2) NPC with LMP-1 expression also have a higher level of TI, indicating that LMP-1 can induce cell apoptosis, which could not be blocked by bcl-2 expression. The authors suggest that LMP-1 expression may exert a dual action on neoplastic cell proliferation and apoptosis in untreated nasopharyngeal carcinoma.

Apoptosis↗
PubMed1999

[Time-effect relationship between the positional microinjection of HCY-2 gene and the neural tube teratogenesis of chick embryos].

The time-effect relationship between positional transferred novel gene(HCY-2) and neural tube teratogenesis, and their possible mechanisms were studied. An eukaryotic expressing vector which containing whole-length HCY-2 cDNA was microinjected into chick embryos in culture at days 0, 1 and 2 (approximately Hamburger-Hamilton stages 1, 6 and 12) mediated by lipofect AMINE reagent. The techniques of RT-PCR, immunohistochemical staining, scanning electron microscope(SEM) and transmission electron microscope (TEM) were used to investigate the expression and distribution of HCY-2 mRNA with its coding product and dysmorphogenesis of the neural tube at 96 h (approximately stage 22). Neural tube defects (NTDs) were discovered in every transferred gene group, only the day 1 embryos which positional site injected was the area pellucida of head, however, the rate of NTDs was the highest (35.3%). There was an obvious time-effect relationship. The phenotypes of NTD were encephalocele, anencephaly, spina bifida and microcephaly. The embryos with transferred gene could express HCY-2 mRNA and its coding product, and the HCY-2 protein mainly distributed in embryonic brain cells as compared to controls. It was found that HCY-2 gene could result in abnormal ultrastructure at the surface and inside of cells under SEM and TEM. It has been observed apoptosis at the sites with NTDs. It is concluded that HCY-2 gene may be a new genotoxic factor, which plays an important role in the mechanisms of neural tube teratogenesis during the early developing stage of embryos.

Animals↗
PubMed1999

[Pathogenic gene analysis of Listeria isolated from foods].

In 1996-1997, Listeria in foods from 12 provinces of China were detected by using the national standard examination method GB 4789.30-94 (routine traditional methods). Twenty four strains Listeria monocytogenes and 141 strains Listeria were identified by biochemical procedures and animal toxicity experiment. Polymerase Chain Reaction(PCR) was used to amplify two specific DNA fragments(719 bp and 446 bp) of listeriolysin O and internalin genes with two pairs of primer--Hly1-2 and Inl1-2, respectively. The experiment results showed that 57 strains contained only internalin, 27 strains contained both internalin and listeriolysin O from the pathogenic genes of isolated strains.

Animals↗
PubMed1999

[Effects of HCY-2 gene transfer on the development of chick neural tube].

In order to explore the relationship between novel gene HCY-2 and neural tube defects (NTDs) and to investigate whether HCY-2 gene was genotoxic, a mammalian expression vector containing HCY-2 cDNA (2014 bp) was transferred into chick fertilized ovum by using lipofectin reagent, then the biological effects of HCY-2 gene on embryos in culture for 3.5 days were observed. Western blotting and immunohistochemistry were used to analyse the expression and distribution of HCY-2 after gene being transferred. HCY-2 gene (5-20 micrograms/chick ovum) could induce NTDs in organogenesis period. Western blotting and immunohistochemical staining showed that HCY-2 protein could be greatly expressed by day 3.5, the time which NTDs developed, with stronger staining at the site of embryonic brain as compared with controls. Under electron microscope, it was observed that HCY-2 gene could damage embryonic cellular ultrastructures and cause excessive apoptosis of neurocytes. These findings suggested that HCY-2 gene with its product was dysmorphogenic to the neural tube, might be a genotoxic factor or teratogenic agent and should be responsible for chick NTDs and probably human NTDs as well.

Animals↗
PubMed1999

[Determination of chlorogenic acid in chrysanthemum morifolium Ramat.flower].

OBJECTIVE: To determine the contents of chlorogenic acid in flower of Chrysanthemum morifolium. METHOD: Column: Nova-Pak C18, 4 microns, 4.6 mm x 250 mm, mobile phase: MeOH-0.1 mol.L-1 NaH2PO4(pH 2.65)30:70, detection wavelength: 328 nm. RESULTS: Flowers of 20 batches bought from the market were analysed. Contents of chlorogenic acid were 0.060%-0.467%. CONCLUSION: Chlorogenic acid is a suitable component for the quality control of C. morifolium.

Chlorogenic Acid↗
PubMed1999

[Effect of bushenjiannao 1 decoction on learning and memory functions and anti-fatigue ability in mice].

OBJECTIVE: To observe the anti-dementia effect of Bushenjiannao 1 decoction on mice. METHOD: The learning and memory tests were realized with a water maze on the learning and memory impact of mice induced by scopolamine and cycloheximide. The effect of Bushenjiannao 1 decoction on the independent activity and anti-fatigue ability of mice were also investigated. RESULT: Bushenjiannao 1 decoction used at a medium dose of 15 g crude drug/kg and a higher dose of 45 g crude drug/kg could significantly improve the learning and memory abilities of mice injected with scopolamine. Higher doses could improve these abilities of mice injected with cycloheximide, and also improve the anti-fatigue ability of mice. No significant differences were observed in the independent activity of mice between the groups. CONCLUSION: Bushenjiannao 1 decoction helps improve the learning and memory abilities and enhance the anti-fatigue ability, but has no effect on excitability of the central nervous system.

Animals↗
PubMed1999

[Forensic medical identification of death due to poisoning of tetrodotoxin in puffer fish].

One case died of poisoning of tetrodotoxin in dry fugu fillet was reported. Through the detailed forensic examination for this lethal case, many questions about forensic medical identification of death due to poisoning of tetrodotoxin was discussed and its medico-legal significance was also discussed. In particular, emphasis was placed on the details of a case, extraction of TTX in specimen, quantitative detection of TTX, purplish mouth and nails, dilatation of stomach and intestines, excluding other causes and combining animal experiment in order to get definite forensic medical identification.

Adult↗
PubMed1999

[An experimental study on bone potentials at fracture site with axial interfragmental gradient compression].

OBJECTIVE: To evaluate the mechanism of stress generated potentials in compressive fixation leading to the primary healing. METHODS: Eighteen fresh sheep tibiae were divided equally into three groups, and all specimen were fractured artificially and imposed "prestressing" at fracture sites with tension device and plate, meanwhile stainless wire tension band was used in the place opposite to plate. The interfragmental pressure was exerted when applied plates, which were 98.62 +/- 19.74 N, 137.93 +/- 8.13 N and 169.20 +/- 11.33 N. Bone potentials at fracture sites were recorded with reference to the potential measurement system by Friedenberg and Brighton (1966). RESULTS: There was no significant statistical difference in bone potentials when made comparison between before and after compression fixation in each group and among groups of different axial interfragmental gradient compressions. CONCLUSION: The mechanism of stress generated potentials may not exist in primary healing with compressive fixation.

Animals↗
PubMed1999

[New high strength titanium alloy Ti-Zr for dental use].

OBJECTIVE: To develop a new titanium alloy which is suitable for prosthodontic use. METHODS: According to the mechanical properties of Co-Cr alloy and type IV dental gold alloy, a new titanium alloy Ti-Zr was developed. RESULTS: The datas of tensile strength(sigma b = 795 MPa, sigma 0.2 = 657 MPa, delta = 22%, E = 100 GPa) and hardness (249 HK) were collected. The microstructure showed a fine crystal grains. CONCLUSION: The new titanium alloy Ti-Zr is suitable for dental use.

Dental Alloys↗
PubMed1999

[The influence of nasal blood flow after ligating external carotid artery and its branches in rabbits].

OBJECTIVE: To study the influence of nasal blood flow after ligation of external carotid artery and its branches. METHOD: We ligate different levels of external carotid artery and its branches, and use laser Doppler flowmetry to observe the change of blood flow in nose before and after operation. RESULT: Among the four types of operation ligating different blood vessels to reduce the blood flow of the operating side, the most effective way is to ligate ipsilateral carotid artery and its branches in the same side. CONCLUSION: After ligation of relating blood vessels, the collateral circulation construct very soon, and the founding speed of that is quicker in the early stage.

Animals↗
PubMed1999

[With periosteal "sandwich" suturing and repairing septonasal perforation by nasal columella degloving].

OBJECTIVE: To recommend a new type of repairing septonasal peforation. METHOD: After a seagull's incision is made around the internal edges of anterior nares and the root of nasal columella, the mucoperiost of nasal septum and nasal bottom is widely dissected through the nasal columella degloving pathway. Then, relaxative incisions are made in bilateral mucoperiost at different directions and bilateral peforations are relaxative sutured at different levels respectively. Meanwhile, an autograft of tibil periost is fixed into nasal septum by the "sandwich" technique. Finally, both nasal cavities are carefully packed. RESULTS: Three cases of septonasal perforation were successfully repaired and have been followed up for 1-2 years respectivelly with no recurrence. CONCLUSION: The characteristics of this operation are: style rather fashionable, pathway rather wide, mucoperiost rather relaxed, suture rather firm and failing rather few.

Adult↗
PubMed1999

[Analysis of 16 cases with aggressive fungal maxillary sinusitis].

OBJECTIVE: To improve the diagnosis and treatment level of aggressive fungal maxillary sinusitis. METHOD: 16 cases were diagnosed with CT. Caldwell-Luc's surgery was done in 13 cases and Lima surgery in 3 cases. None of them were treated by antifungal agents. RESULT: It showed osteolytic damage with bony defect which was different from expanded bony defect caused by benign tumor, but similar to malignant tumor. No recurrence occurred as followed from 6 months to 2 years. CONCLUSION: Computed tomography is very important in its diagnosis. Early explorative operation is useful in making definite diagnosis.

Adult↗
PubMed1999

[Applied anatomy of anterior ethmoid relevant to endoscopic transnasal dacryocystorhinostomy].

OBJECTIVE: This study provided clinical guidance for the endoscopic transnasal dacryocystorhinostomy. METHOD: 16 adult cadavers were studied on the applied anatomy of between anterior ethmoid and fossa of lacrimal sac and the anatomic relationship between uncinate process and medial wall of orbit. RESULT: According to the anatomic relationship between anterior ethmoid sinus and fossa of lacrimal sac, the cells of anterior ethmoid sinus were classified into three typies, The results was that type I accounted for 31.2%, type II 50.0% type III 18.8%. CONCLUSION: CT scans should be performed to determine the anatomic relationships between fossa of lacrimal sac and anterior ethmoid and between uncinate process and medial wall of orbit before operation for patients with different typies of obstruction of nasocrimal duct, thus the proper bony opening was located during dacryocystorhinostomy.

Adult↗
PubMed1999

[A rapid separation and quantitation of sodium cyclamate in food by ion-pair reversed-phase high performance liquid chromatography].

A method of separation and quantitation of sodium cyclamate in foods by ion-pair reversed-phase high performance liquid chromatography is described. Sodium cyclamate can be separated on ODS column at room temperature by using a mobile phase of V(methanol):V(water, containing ion-pair reagent) = 30:70 at 1 mL/min flow rate. The effects of ion-pair reagent and methanol on the retention of sodium cyclamate were studied. The samples were quantified with an ultraviolet detector operated at 205 nm. The calibration curve was linear in the range of 0.50-2.50 g/L with a correlation coefficient of 0.9996. The recoveries were 96.9%-101.7%. The detection limit was 0.05 g/L. This method is simple, rapid and sensitive.

Calibration↗