Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 649 records · Page 36Linked to original sources

PubMed1999

[Two-dimensional finite element analysis for morphology of craniofacial hard tissue of people with anterior crossbite at early permanent dentition].

OBJECTIVE: To analyze the morphology of craniofacial hard tissue of people with anterior crossbite at early at early permanent dentition. METHODS: The craniofacial morphology of hard tissue of 80 cases anterior crossbite of the early permanent dentition was analyzed by a special computer software system for finite element analysis of two-dimensional cranio-facial structure. RESULTS: The size change of each element was smaller than shape change in cross-bite group, which suggested that the shape change was the main element change; The posterior cranial base was found abnormal in both male and female groups, with counterclockwise rotation occurring at posterior cranial base to some extent; The upper part of face and the maxillary suffered underdevelopment in both male and female groups; The most outstanding change in size and shape occurred at anterior and superior part of mental, with each component of counterclockwise rotation to varying degree. CONCLUSION: Abnormality that occurs in craniofacial hard tissue of people with anterior crossbite at early permanent dentition period is highlighted by abnormal skeletal shape change and rotation, and may be one of the fundamental factors causing crossbite.

Adolescent↗

PubMed1999

[Telomerase hTRT mRNA expression in oral squamous cell carcinogenesis].

OBJECTIVE: To investigate the relationship between telomerase hTRT gene expression and malignant development of oral mucosa epithelium. METHODS: 82 cases were detected by in situ hybridization technique for hTRT gene, including 7 cases of normal oral mucosa, 7 cases of hyperplasia lesions, 30 case sof oral precancerous lesions (dysplasia lesion), 8 cases of oral mucosa carcinoma in situ and 30 cases of oral squamous cell carcinomas. RESULTS: 1. Weaker expression of hTRT mRNA was observed in normal oral mucosa and hyperplasia lesions. Positive cells were present in basal layer and parabasal layer, and hTRT positivity was 21.4% (3 of 14). 2. The expression of hTRT mRNA in the precancerous lesions was gradually strong associated with phenotypic progression and the degree of dysplasia. Positive cell extended to multi-layered epithelium, and hTRT positivity was 46.7% (14 of 30). 3. Strong hTRT mRNA expression was observed in squamous cell carcinoma, and the positivity was 81.6% (31 of 38). CONCLUSION: Telomerase hTRT gene expression is closely related to the malignant degree of oral mucosa, the reactivated telomerase may play a crucial role in the progression of oral cancer.

Carcinoma, Squamous Cell↗

PubMed1999

[Malignant external otitis: 4 cases report].

OBJECTIVE: To improve the level of diagnosis and treatment of malignant external otitis (MEO). METHOD: Four cases with MEO were reported. RESULT: Three in four cases were followed up. One patient was cured, and the others died of intracranial infection. CONCLUSION: Early diagnosis of MEO is very important for treatment. The patients of MEO with diabetes often died of intracranial infection.

Aged↗

PubMed1999

[The value of nasal endoscopy in the resection of upper and posterior nasal septum deviation].

OBJECTIVE: In order to find a safe, reliable and satisfying technique to treat the upper and posterior nasal septum deviation. METHOD: Performing the resection of the upper and posterior nasal septum deviation under nasal endoscopy, comparing this new method with the traditional one and discussing the safety and long-term curative effect of this new method. RESULT: The observation of the outcome of 109 patients undergoing this operation after 1-50 months postoperation shows that this technique can resect the upper and posterior deviation safely and completely, improve the nasal respiratory and olfactory function and reduce the occurrence of nasal cavity adhesion and the recurrence of nasal polyp and sinusitis. CONCLUSION: Performing the resection of the upper and posterior nasal septum deviation under nasal endoscopy is a good method for popularizing to clinician.

Adult↗

PubMed1999

Method development of adsorbed stationary phase open tubular capillary electrochromatography.

The adsorption effect of capillary wall, which was usually considered as a troublesome factor, has been used as driving force for preparing stationary phase for open tubular capillary electrochromatography (OTCEC). A number of compounds have been applied as stationary phase materials, which include cationic surfactants such as cetyltrimethylammonium bromide (CTAB), basic proteins such as lysozyme and cytochrome C, basic peptides such as Lys-Tyr and Lys-Ser-Tyr, and basic amino acid L-lysine. The adsorbed CTAB phase is used for separation of neutral compounds while other adsorbed stationary phases are used for chiral separation. The run-to-run reproducibility of retention time is rather good with RSD values less than 2.3%. The separation efficiency is excellent with the highest theoretical plate number of up to 590,000/m and the average plate number of more than 250,000/m. Being stored at 2-8 degrees C in refrigerator, the adsorbed stationary phase can last at least one month.

Adsorption↗

PubMed1999

[Preparation and evaluation of open tubular capillary electrochromatographic columns by sol-gel method].

Open-tubular capillary electrochromatographic columns were prepared by sol-gel method. The influence of pH of gel solution on the column performance was investigated with a series of gel solution prepared by hydrochloric acid at different pH value. The results show that the pH of gel solution influences the capacity factors (k') of solutes in a complex way. The general trend is that the values of k' increase as the pH value increases except that at pH of 2.0. The gel solution of pH 2.8 was selected to prepare the column, at which the greatest capacity factors can be obtained within an acceptable reaction rate. The influence of reaction time of gel solution in column was also investigated. Out of expectation, the k' value didn't increase with increase in reaction time. The reason may be that the pore of silica gel is so small that the sample molecule can't migrate into it. The surface area is only offered by outer surface of silica gel, so the phase ratio of column prepared by this method is still not large enough. It was found that the joule heat effect can be neglected since the capillaries used were very small in inner diameter. The electroosmotic flow plays an important role in the separation as it determines the separation time. In order to accelerate the separation, high pH condition is necessary. Therefore, the stability of column under high pH is very important. The column shows a good stability under pH 9 of the mobile phase. The relative standard deviations (RSD) of capacity factor of four solutes were less than 3.7% for 100 times of operations. The separation efficiency was evaluated and the average theoretical plate numbers under optimal conditions for thiourea, phenetole, naphthalene, biphenyl, and 2,6-dimethyl naphthalene were 4.66 x 10(5), 5.24 x 10(5), 5.02 x 10(5), 4.77 x 10(5), and 3.58 x 10(5)/m, respectively. The column shows good repeatability. The RSD values for k' are less than 1% and the RSD values for efficiency are less than 8% (n = 5). In addition, fast separation was obtained with shorter column and higher voltage used, where four aromatic compounds were baseline separated in 101 s.

English Abstract↗

PubMed1999

[Effects of temperature on the migration time window of micellar electrokinetic capillary chromatography].

The effects of capillary temperature, the nature and concentration of buffer on the migration time window of micellar electrokinetic capillary chromatography are investigated through three parameters including electroosmotic mobility (micro eo), the electrophoretic mobility micelle (micro ep,mc) and mobility ratio (Rm,mc). (micro eo) and (micro ep,mc) increase linearly as capillary temperature increases. Change in the viscosity of the running buffer is the main factor in the temperature effect. It is proved theoretically that the local viscosity at the capillary wall is different from the bulk viscosity. The increasing rate of micro eo with temperature is different from that of micro ep,mc. The migration time window can be expanded by lowering capillary temperature. Although the expanding is limited, this method can be very easily achieved on a commercial apparatus. A uniform formula has been derived to describe the relationships between micro eo, micro ep,mc and the concentration of buffer. For Tris and borate buffer, both micro eo and micro ep,mc decrease with increasing buffer concentration, but the decreasing rate is limited. Thus the effect on the migration time window is not significant. For phosphate buffer, the effects on micro eo and micro ep,mc are different in different concentration ranges. micro eo decreases rapidly in low concentration range but decreases slowly in high concentration range with increasing buffer concentration. micro ep,mc decreases in low concentration range but increases in high concentration range with increasing buffer concentration. The migration time window can be significantly expanded by increasing the concentration of phosphate buffer.

English Abstract↗

PubMed1999

[An experimental method for measuing flexor pulley's mechanical effects by imitating hand in vivo].

Flexor pulley system has an important mechanical effect on digital flexion function. An experimental method was designed to measure the pulleys' mechanical effects by using hand in vitro to imitate hands in vivo. The pulleys' function was evaluated by pulley incision and pulley preservation, and percentage loss of work was used as an index. The results demonstrate that this experiment is reasonable in design and methodology.

Adult↗

PubMed1999

[Gas chromatographic method for the analysis of polychlorinated biphenyls in pine needles].

Polychlorinated biphenyls (PCBs) are a class of 209 chemical compounds, in which 1-10 chlorine atoms are attached to a biphenyl molecule. PCBs are members of halogenated aromatic group of environmental pollutants that have been identified worldwide in diverse environmental matrices. PCBs in air, soils, sediment, water, transformer oils and other environmental matrices have been determined in the past years. In this work a method for routine analysis of PCBs in pine needles has been developed. First, extractions were carried out in Soxhlet apparatus with n-hexane as solvent. Then, a silica gel chromatographic column was applied to pretreat the pine needle samples. The reference standard used was clophen 50. The recovery was about 90%, so the feasibility and reliability were assured. After the analysis of PCBs in pine needle samples from four different regions, the distribution of PCBs in environment can be discussed and monitored. In this method, a Shimadzu GC-7A gas chromatograph equipped with a 63Ni electron capture detector was used for the analysis of PCBs. From the results, we can see the PCB pollution in different regions. So evaluation of air pollution level through foliage data is feasible. The sample preparation and analytical method mentioned in this paper is reliable and simple.

Chromatography, Gas↗

PubMed1999

[The advances of the study on the optical chromatography].

This review is mainly concerned with the recent developments in (1) the differences between the optical tweezer and optical chromatography; (2) the principle of optical chromatography separation; (3) the theory studies on the optical chromatography, especially the relationship between the particle radius with the intensity of the applied laser radiation force and the relationship between the particle retention distance with the particle radius; (4) the application of the optical chromatography technique to the separation of polymers, biological macromolecules and biological cells. The application of optical chromatography to the immunoassy and molecular biology is highlighted.

Chromatography↗

PubMed1999

[Taxonomic study of four isolates of Saccharomonospora].

Four strains, 19.1, 22.1, 202, and 212, were isolated from the soil samples of Guangxi province in China. Basing on their morphological and cell chemical characteristics(cell wall type IV, sugar type A, without mycolic acids), they were circled into the genus of Saccharomonospora. They were studied with 7 type strains of the 5 currently recognized species in the genus. The results of Ribotyping suggest that strain 19.1 blongs to the species of S. viridis, strain 202 is a member of S. caesia, strain 22.1 and strain 212 are the same species, which is different to the 5 currently known species. It is closely related to S. viridis. However, the further classification of these two strains at species level needs 16S rRNA sequence date.

Actinomycetales↗

PubMed1999

[Preliminary study of P19 gene from Bacillus thuringiensis subsp israelensis].

The P19 gene and cyt1A gene were obtained by PCR with 9.7 kb HindIII fragment containing P19 gene and cyt1A gene from 72 MD plasmid of Bt as a template. Digested PCR products were ligated to expression vector pUHE24 and transformed into E. coli XL-1. Three clones, LZ19 harboring P19 gene, LZcyt1A harboring cyt1A gene, LZ19A harboring P19 gene and cyt1A gene, were screened. The growth cure of cloned strains were determined under IPTG induction. The result showed that pLZ19 did not affect the growth of E. coli, pLZcyt1A is typically Lethal for E. coli, Lethal initial efficiency of pLZ19A is much higher than that of pLZcyt1A. Probably, this was a result that P19 gene enhanced initial expression of cyt1A gene in E. coli.

Bacillus thuringiensis↗

PubMed1999

[Studies on the metabolism pathway of aniline degradation by Comamonas acidovorans AN3].

All of the enzymes relating to aniline degradation in C. acidovorans AN3 were inducible ones. When growing on aniline as sole carbon, nitrogen and energy sources, the cells of C. acidovorans AN3 contained aniline dioxygenase, catechol-2, 3-dioxygenase, 2-hydromuconic semialdehyde dehydrogenase, 4-oxalocrotonic acid decarboxylase and 4-hydroxy-2-oxovalerate acid aldolase. The Km and Vmax of aniline dioxygenase were 292 mumol/L and 3.57 mumol.mg-1. min-1, respectively. The Km and Vmax of catechol-2, 3-dioxygenase were 16.4 mumol/L and 15.2 mumol.mg-1.min-1, respectively. According to these results, the degradation metabolism pathway of aniline by C. acidovorans AN3 was hypothesised.

Aniline Compounds↗

PubMed1999

[Humoral immune response in mice to hybrid nucleic acid vaccines containing Plasmodium falciparum merozoite surface protein 1 block 17-based gene].

AIM: To analyse the humoral immune response in mice to nucleic acid vaccines (VR1012/HG-MSP1-17 for intracellular expression or VR1012/TPA/HG-MSP-17 for secretion) containing Plasmodium falciparum merozoite surface protein 1 (MSP1) 17 block gene and gene fragment of several T cell epitopes from MSA1, MSA2, RESA, IL-1 and TT. METHODS: BALB/c or C57BL/6 mice received three times intramuscular immunization with 200 micrograms/100 microliters or 100 micrograms/100 microliters of VR1012/HG-MSP1-17 or VR1012/TPA/HG-MSP1-17 per mouse each time. Anti-HG or anti-MSP1-17 antibodies were monitored by indirect ELISA. RESULTS: BALB/c and C57BL/6 mice immunized with 100 micrograms/100 microliters of VR1012/HG-MSP1-17 per mouse raised significantly anti-HG and anti-MSP1-17 antibodies, but the levels of antibodies were not high. BALB/c mice immunized with 200 micrograms/100 microliters of VR1012/HG-MSP1-17 per mouse raised higher anti-HG antibodies but not anti-MSP1-17 antibodies. BALB/c mice immunized with 200 micrograms/100 microliters of VR1012/TPA/HG-MSP1-17 per mouse raised low level of anti-HG antibodies only. CONCLUSION: VR1012/HG-MSP1-17 is more immunogenic than VR1012/TPA/HG-MSP1-17.

Animals↗

PubMed1999

[The clinical characters of myopatic pharyngoparalysis and laryngoparalysis with 3 cases report].

OBJECTIVE: To improve the level of diagnosis and treatment about myopathic pharyngoparalysis and laryngoparalysis (MPL). METHOD: 3 cases of MPL were diagnosed by clinical inaterials, electromyogram, serokinase and muscle biopsy. The clinical characters are dysphagia, phonasthenia, abnormal electromyogram and high CPK et al. They were all treated with glucocorticoid. RESULT: The effect of treatment on all 3 cases was good. CONCLUSION: It is important to distinguish MPL with neuropathic pharyngoparalysis and laryngoparalysis. An appropriate glucocorticoid treatment is also impontant.

Adolescent↗

PubMed1999

[Clinical use of nasal airflow measurement in septoplasty].

OBJECTIVE: To discuss the clinical use of nasal airflow measurement in septoplasty. METHOD: After nasal decongestion, 21 patients's nasal airway resistance and nasal airflow were evaluated by anterior rhinomanometry before and after submucous resection of nasal septum. RESULT: The amount of nasal airflow asymmetry could show nasal respiratory function better than nasal airway resistance does, the patients with absolute amount of nasal airflow asymmetry greater than 50% had bad postoperative outcome, patients' satisfication with operation was significantly correlated with the presence of post-operative symmetrical nasal airflow. CONCLUSION: The amount of nasal airflow asymmetry can serve as an indicator of patient selection, outcome evaluation and prognosis in nasal septum deviation.

Adult↗

PubMed1999

[Clinical and bacteriology observation on intraoperation usage of tarivid otic solution in treatment of chronic otitis media with cholesteatoma].

OBJECTIVE: To determine the effect and safety of Tarivid (oflorxacin) otic solution used during the operation in treatment for chronic otitis media with cholesteatoma. METHOD: 42 patients were divided into two groups. In Tarivid group, 23 patients' operative cavities were soaked with 0.3% Tarivid, while other 19 patients' operative cavities in boric acid group were soaked with 4% boric acid during the open mastoidectomy with tympanoplasty. RESULT: The recovery rate was 82.6% and 50% respectively. There was significant difference between two groups (P < 0.05). No side effect was observed. CONCLUSION: It shows that using Tarivid otic solution in the operation can improve the outcome of the operation and has high security.

Adult↗

PubMed1999

[Isolating, cloning, and sequencing of HPV16E6E7 gene from a cervical carcinoma biopsy in Shandong Province].

OBJECTIVE: In order to study the structure specificity of HPV16E6E7 gene of a Chinese patient of cervical carcinoma in Shandong province. METHODS: The tissue DNA were abstracted from cervical carcinoma biopsies and the type of HPV was identified by HPV multiple primers PCR. HPV16E6E7 gene was amplified by PCR from the cervical carcinoma tissue DNA with the infection of HPV16 type only, and then cloned the E6E7 gene into pALTERI vector. After sequencing the double strand, the gene was compared with the prototype E6E7 gene of HPV16. RESULTS: A new recombinant plasmid was constructed and named HPV16E6E7-SD. Sequencing results showed one mutation in HPV16E6E7-SD, the 557th neocleotide in the viral neocleotide sequence "T" was changed into "C", and caused the termination cordon TAA of E6 gene to convert into a Gln cordon CAA. CONCLUSIONS: There is a structure difference between HPV16E6E7-SD and the standard strain.

Base Sequence↗