Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 469 records · Page 26Linked to original sources

PubMed2000

[Estrogen receptor gene polymorphism and its association with clinicopathological manifestation of lupus nephritis].

OBJECTIVE: To investigate the distribution of estrogen receptor (ER) in patients with lupus nephritis (LN), and the association between ER gene polymorphism and the clinical and pathological features of the disease. METHODS: The Pvu II and Xba I restriction fragment length polymorphism (RFLP) of estrogen receptor gene were analyzed in 245 biopsy proven LN patients (58 males and 187 females) and 172 normal controls(101 males and 71 females) by PCR-RFLP. The clinical and pathological features of 49 male and 152 female LN patients with genotype PpXx or Ppxx, ppxx were then analyzed respectively. RESULTS: It was found that genotype PpXx and ppxx, Ppxx were three major genotypes of ER gene in both lupus patients group and control group. The distribution of ER gene polymorphism was quite different in lupus patients of different genders. The frequency of the PpXx genotype was significantly higher in male LN patients than in both the gender matched normal controls (P<0.05) and the female LN patients (P<0.05), while no difference was shown in the frequency of PpXx genotype between female LN patients and female controls. Interestingly, varied clinical and renal pathological features were also demonstrated in female patients with different genotypes of ER gene. CONCLUSION: The distribution of ER gene polymorphism in LN patients varies with gender. The PpXx genotype of ER gene may be associated with the susceptibility of LN in male. ER gene polymorphism is probably one of the genetic factors contributing to the development of clinical heterogeneity and sexually dimorphic manifestations of LN.

Adolescent↗

PubMed2000

Doxycycline inhibition of interleukin-1 in the corneal epithelium.

PURPOSE: To evaluate the effect of doxycycline on the regulation of interleukin (IL)-1 expression and activity in human cultured corneal epithelium. METHODS: Human corneal limbal epithelium (HLE) was cultured from explants prepared from limbal rings of donor corneas. Primary cultured limbal epithelial cells were treated with either 10 microg/ml lipopolysaccharide (LPS), LPS with 10 microg/ml doxycycline, or LPS with 0.1 mg/ml methylprednisolone (MP) for 24 hours. The intracellular and supernatant protein amounts of IL-1alpha, the precursor and mature forms of IL-1beta, IL-1 receptor antagonist (IL-1 RA), and the intracellular level of IL-1beta-converting enzyme (ICE) were measured with enzyme-linked immunosorbent assays (ELISAs). Western blot analysis was performed to evaluate IL-1 RA protein. mRNA steady state amounts were determined by RNase protection assay (RPA) for IL-1alpha, IL-1beta, IL-1 RA, and ICE. RESULTS: LPS increased the mRNA and protein amounts of intracellular and released IL-1alpha, mature IL-1beta, and IL-1 RA. Doxycycline inhibited the LPS-induced IL-1beta increase in the mRNA and protein amounts in the corneal epithelium and upregulated the expression of the anti-inflammatory IL-1 RA protein. In addition, doxycycline reduced the steady state level of the cellular ICE protein but did not affect the level of ICE transcripts. IL-1beta secreted to the conditioned media of HLE was functionally active in inducing matrix metalloproteinase (MMP)-1 and MMP-3 in cultured corneal fibroblasts. Doxycycline significantly decreased IL-1beta bioactivity in the supernatants from LPS-treated corneal epithelial cultures. These effects were comparable to those induced by the corticosteroid, MP. CONCLUSIONS: Doxycycline can suppress the steady state amounts of mRNA and protein of IL-beta and decrease the bioactivity of this major inflammatory cytokine. These data may partially explain the clinically observed anti-inflammatory properties of doxycycline. The observation that doxycycline was equally potent as a corticosteroid, combined with the relative absence of adverse effects, makes it a potent drug for a wide spectrum of ocular surface inflammatory diseases.

Anti-Bacterial Agents↗

PubMed2000

Towards a fibrous composite with dynamically controlled stiffness: lessons from echinoderms.

Sea urchins and sea cucumbers, like other echinoderms, control the tensile properties of their connective tissues by regulating stress transfer between collagen fibrils. The collagen fibrils are spindle-shaped and up to 1 mm long with a constant aspect ratio of approx. 2000. They are organized into a tissue by an elastomeric network of fibrillin microfibrils. Interactions between the fibrils are regulated by soluble macromolecules that are secreted by local, neurally controlled, effector cells. We are characterizing the non-linear viscoelastic properties of sea cucumber dermis under different conditions, as well as the structures, molecules and molecular interactions that determine its properties. In addition, we are developing reagents that will bind covalently to fibril surfaces and reversibly form cross-links with other reagents, resulting in a chemically controlled stress-transfer capacity. The information being developed will lead to the design and construction of a synthetic analogue composed of fibres in an elastomeric matrix that contains photo- or electro-sensitive reagents that reversibly form interfibrillar cross-links.

Animals↗

PubMed2000

Dopamine receptor gene polymorphisms in Guangzhou Hans.

OBJECTIVE: To determine the distribution of dopamine D2, D3, and D5 receptor(DRD2, DRD3, DRD5) gene polymorphisms in Guangzhou Hans. METHODS: A total of 141 healthy Guangzhou Hans were studied by the use of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and PCR-amplification of specific allele (PASA) techniques. Current results were compared with the data on other ethnic groups. RESULTS: Within the 141 individuals tested, the frequencies of the A1(Taq I-) and A2(Taq I+) alleles of the TaqI A mutation site in the 3'non-coding region of the DRD2 gene were found to be 48% and 52%, respectively. The observed frequencies of the A1A1, A1A2 and A2A2 genotypes were found to be 17%, 52% and 31%, respectively, which met Hardy-Weinberg equilibrium. The frequencies of the A1 and A2 alleles of the Bal I mutation site in the exon 1 of DRD3 gene were found to be 73% and 27%, respectively. The observed frequencies of the A1A1, A1A2 and A2A2 genotypes were found to be 53%, 39% and 8%, respectively, which met Hardy-Weinberg equilibrium. The frequencies of the 1 and 2 alleles of the Msp I mutation site in the intron 5 of DRD3 gene were found to be 62.5% and 37.5%, respectively. The observed frequencies of the 1-1, 1-2 and 2-2 genotypes were found to be 35%, 55% and 10%, respectively, which met Hardy-Weinberg equilibrium. No linkage disequilibrium was observed between the Bal I and Msp I polymorphism in Guangzhou Hans(chi(2)=0165, P>0.05). The frequencies of the T and C alleles of the T978C mutation site of DRD5 gene were found to be 51% and 49%, respectively. The observed frequencies of the T/T, T/C and C/C genotypes were found to be 23.6%, 54.6% and 21.8%, respectively, which met Hardy-Weinberg equilibrium. CONCLUSION: The polymorphisms of DRD2, DRD3, DRD5 gene in Guangzhou Hans were high and different from those in other populations.

Adult↗

PubMed2000

On the viscoelastic character of liver tissue: experiments and modelling of the linear behaviour.

This paper presents the results of recent investigations into the viscoelastic character of liver tissue, especially the linear response. The linear domain of liver tissue has been determined by a strain sweep oscillation test. The fluid-like viscoelastic behaviour of liver tissue was confirmed by stress relaxation experiments. To demonstrate the consistency and quality of the experimental data, the relaxation spectrum was used to reconstruct the relaxation modulus, as well as the storage and loss moduli. The generalised Maxwell model was successfully employed to model the mechanical behaviour in the linear viscoelastic domain.

Animals↗

PubMed2000

[Analysis of the interaction of the polymorphisms of presenilin-1 gene and ApoE gene in Alzheimerns disease].

OBJECTIVE: To explore the interaction of the polymorphism of 3' -terminal intron of the eighth exon of presenilin-1(PS-1) gene with the polymorphism of apolipoprotein E(ApoE) gene in the pathogenesis of sporadic Alzheimerns disease(SAD). METHODS: The polymorphisms of 3'-terminal intron of the eighth exon of presenilin-1 gene and ApoE gene were detected by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique in 75 patients with SAD and 73 normal controls. RESULTS: The polymorphisms of PS-1 gene and ApoE gene were associated obviously with SAD. The onset of SAD was negatively associated with allele 2 of PS-1 gene and E(2) allele of ApoE gene,and it was positively associated with allele 1 of PS-1 gene. The onset of SAD was not associated with E(3) allele and E(4) allele of ApoE gene. CONCLUSION: These results indicated that allele 2 of PS-1 gene and E(2) allele of ApoE gene might protect people from SAD, that allele 1 of PS-1 gene might increase the risk of the onset of SAD, and that the onset of SAD was not associated with the interaction of the polymorphisms of PS-1 gene and ApoE gene.

Aged↗

PubMed2000

[Is Gly460Trp variant of alpha-adducin associated with essential hypertension in the Hans of Chinese population].

OBJECTIVE: To determine whether the variant of adducin alpha subunit (alpha-adducin) is in association with essential hypertension in the Hans of Chinese population. METHODS: One hundred and eighty-three patients with essential hypertension and 129 normotensive subjects were included in this study. Genomic DNA was isolated from 3 ml of whole blood. Polymerase chain reaction, single-strand conformational polymorphism and DNA sequencing analysis techniques were used to detect the variant in the exon 10 of alpha-adducin gene. The clinical data of height, weight and blood pressure were also measured in all subjects. RESULTS: A G-->T substitution at nucleotide 614 in exon 10 of alpha-adducin gene which resulted in the Gly460Trp variant was found in the Hans. The distribution of Gly/Gly, Gly/Trp and Trp/Trp genotypes was coincident with Hardy-Weinberg equilibrium and there were no statistical differences in the three genotypes and Trp allele frequencies between hypertensive and normotensive subjects (P>0.05). The variant of alpha-adducin genotypes was not associated with any significant differences in age, body mass index and blood pressure. CONCLUSION: A G-->T substitution at nucleotide 614 in exon 10 of alpha-adducin gene is found, but there is lack of the association between the variant of alpha-adducin gene and essential hypertension in the Hans of Chinese population.

Adult↗

PubMed2000

[Analysis of ultrasonic backscattering microstructure feature of human spleen based on "WD cepstrum"].

A new method "WD cepstrum" for analysing ultrasonic scattered signals based on wavelets decomposition before cepstrum has been developed and then applied to process the backscattered signals of normal and pathological human spleen in vitro. The mean scatterer spacing(MSS) has been estimated. The results show that the MSS data of the two tissues are quite different and "WD cepstrum" is more effective for reflecting the microstructure feature of tissue. The results also illustrate that "WD cepstrum" is an effective method for signal analysis of ultrasonic scattering and characterization of tissue scatterers.

Humans↗

PubMed2000

[The research advance of brain derived neurotrophic factor].

Recent research advances in neuroscience show that neurotrophic factors are proteins that affect selectively various kinds of neurons of CNS and PNS. Brain derived neurotrophic factor (BDNF) is another neurotrophic factor that was first reported by Barde, a German chemist, thirty years later after the nerve growth factor had been found out. BDNF plays an important role in the growth, development, differentiation, maintenance and regeneration of various types of neurons in the CNS and has potential application to the treatment of brain injury and neurodegenerative diseases such as Alzheimer's disease, Parkinson's syndrome, Huntington's chorea and amyotrophic lateral sclerosis. In this paper, the structure, function and potential clinical application of BDNF were reviewed.

Animals↗

PubMed2000

[One-dimensional impact dynamic response of cancellous bone].

In this paper a one-dimensional dynamic response of cancellous bone to impact loading is investigated. It is demonstrated, based on the studies with scanning electron microscope, cancellous bone could be viewed as a cellular solid consisting of an interconnected skeleton filled with medulla. A two-phase poroelastic model is introduced to describe the cancellous bone, in which the tissue(material) densities of the skeleton and medulla are assumed to be unchangeable while the corresponding apparent densities are changeable due to the change of volume fraction, the governing equations are derived for the case of a linear poroelastic solid skeleton saturated with an inviscid medulla. Under the impact loading, responses of the skeleton displacement and stress as well as the medullary pressure are obtained with the use of Laplace transform technique. The computational result shows that the cancellous bone is provided with certain features similar to those appearing in viscoelastic solids, which means that the responses do not only depend on time, but furthermore depend on previous loading history. It is worth paying attention to the result that the medullary pressure can be negative. This point is due to the recovery of the skeleton after unloading whereas the medulla is not squeezed out but absorbed into the pores by suction.

Biomechanical Phenomena↗

PubMed2000

Influence of amalgam on the growth of mutans streptococcus: an in vivo study.

OBJECTIVE: To study the antibacterial activity of dental amalgam against mutans streptococcus. METHODS: Study volunteers included 14 patients, 21 to 35 years old, with aged amalgam fillings, with no antibiotic use during the previous 3 months, and 16 patients, 22 to 24 years of age, without aged amalgams, but with unfilled caries. Plaque samples were collected once from the subjects with aged amalgams. Subjects with fresh amalgams had plaque samples collected at 1 day, 1 week, 2 weeks, 4 weeks, and 8 weeks after amalgam restoration. As controls, plaque samples were collected from unrestored occlusal enamel surfaces on the same side, or on the opposite side of the same occlusion. Frequency of mutans streptococci from aged amalgams and fresh amalgams and the colony-forming units (CFU) were tested. RESULTS: The difference of CFU of mutans streptococci in the plaque samples between the amalgam restorations, the aged amalgams, and the controls was not significant within 8 weeks after amalgam filling. The difference of CFU of mutans streptococci in plaque samples from the amalgam restorations between all the timepoints was significant except between the fourth week and eighth week. For the control group, however, the difference in values between the first day and the timepoints afterward were significant, except between the first day and the first week. The difference between the first week and later timepoints was significant, but not between the second week and later, or between the fourth week and later. At the eighth week, the difference between the aged-amalgam and controls was not significant. CONCLUSION: Amalgam had some inhibitory effect on the in vivo growth of mutans streptococci.

Adult↗

PubMed2000

Acidogenicity and acidurance of fluoride-resistant Streptococcus sobrinus in vitro.

OBJECTIVE: To induce fluoride-resistant mutants of Streptococcus sobrinus in vitro and to study the acidogenic and acid tolerance of fluoride-resistant strains. METHODS: Fluoride-resistant mutants 6715-FR and S1-FR were obtained by subculturing S. sobrinus 6715 and freshly isolated S. sobrinus SSMU-S1 to media TSA or TSB, which contained different concentrations of fluoride. The lactic production and growth of fluoride-resistant strains and their respective parent strains were measured by gas chromatography and ultra-violet visible spectrophotometer. RESULTS: The stable fluoride-resistant mutants of S. sobrinus had been induced successfully in vitro. The acid production of 6715-FR or S1-FR was significantly greater than their parent strains in the presence of 0.5 or 5.0 mM fluoride. In the absence of fluoride, there were 2 situations: The lactic production of F-resistant S. sobrinus was less than or equal to its parent strains when initial pH value was above 5.0 while the result was the opposite when pH value was below 5.0. The F-resistant strains and the parent strains of S. sobrinus could reduce the suspension pH to identical values in the absence of fluoride, and the F-resistant strains were more aciduric in the presence of fluoride. CONCLUSIONS: The F-resistant strains of S. sobrinus had higher acidogenic and aciduric ability than the wild-type strains, and were expected to have stronger cariogenic potential at plaque fluoride levels.

Acids↗

PubMed2000

[Studies on clinical trials and immune effect of a new purified rabies vaccine prepared from Vero cells].

OBJECTIVE: To observe the safety and neutralizing antibody response of a new purified rabies vaccine prepared from Vero cells. METHODS: The vaccine used was manufactured in Hainan Institute of Biologicals and licensed by the Ministry of Health for clinical trials. The vaccine was administrated in 30 and 318 volunteers during phase I and II clinical trials with preexposure (day 0, 7, and 28) or post exposure (day 0,3,7,14 and 28) vaccination schedules. The "Verorab (PVRV)", a rabies vaccine made in France was used as control. RESULTS: The results showed that the new purified vaccine did not cause any severe and moderate side reactions, the slight side reaction rate was 12% including those complained by vaccines themselves. The immunological effect was determined by detecting neutralizing antibody with mouse neutralization test (NIH). The positive seroconversion rates of neutralizing antibody were 100% (n= 27, GMT 2.89 IU/ml) and 100% (n= 30, GMT 5.29 IU/ml) respectively by pre- exposure and post exposure schedules. No significant difference was found when compared with France "Verorab" vaccine by preexposure schedule (n= 24, GMT 2.13 IU/ml). CONCLUSIONS: The clinical trials indicated that the purified rabies vaccine prepared from Vero cells only showed slight side reaction and had good neutralizing antibody response. Therefore this new vaccine is safe and protective for the prevention of rabies in human.

Animals↗

PubMed2000

[Establishment and application of Z-HL16C cell line].

OBJECTIVE: Human embryonic lung fibroblasts at 8th passage was presented to us by the Institute of Virology. At its 16th passage,under the culture condition of our laboratory, the lung fibroblasts changed into epithelial like cells. We attempted to establish a cell line and applied it for virus isolation. METHODS: The cells were continuously passaged, cloned, the cell morphology, growth capacity and chromosome number were determined. RESULTS: The cell size appeared uniform, cell boundary was distinct, the cell recovery rate after frozen storing was above 90%. The cell replicated permanently and now it has been passaged 136 times. The chromosome number has changed from 46 to 110. We named this cell line the ZHL16C. It proved to be sensitive to these viruses tested: enteroviruses (Polio, Cox, Echo), influenza viruses, parainfluenza viruses, adenoviruses, measles virus, herpes simplex and herpes zoster viruses, cytomegalovirus, rubella virus and respiratory syncytial virus. When using Z-HL16C cell to isolate virus from 29 adenovirus swab samples collected from 29 soldiers with epidemic high fever in a new military, adenovirus type 3,7 coxsackie virus types B1, B5, B5, B5, B5 were isolated. CONCLUSIONS: The cell line HL16C has been stably established, it has a broad spectrum in sensitivity for viruses.

Cell Culture Techniques↗

PubMed2000

[The first western style doctor in modern China - Guan Tao].

Guan Tao (Guan Yadu, Kuan A - To) is the first western style doctor and the first military western style doctor in the medical history of China. He was from the generations of the business painter in Shi San Hang (Thirteen Factories) of Guangzhou, in which the culture environment exerted a great influence on him. His uncle Guan Qiaochang (Lam Qua) and Guan Lianchang (Tin Qua) were famous business painters of Guangdong in 19th century. Guan Qiaochang set up a workshop in Shi San Hang and had extensive contact with various foreigners from Europe and North America. He followed the western style of the paintings from George Chinney who was a famous painter of England, settled down in Macao for the rest of his life during this period. Under the guidance of Guan Qiaochang, Guan Tao studied western medicine under the instruction of Peter Parker, the first American medical missionary in China, at the Ophthalmic Hospital in Shi San Hang in 1837, Guan Tao became a western style doctor with excellent character, skill and devotion. Chinese people remember his name forever.

China↗

PubMed2000

[Coupling effect of water and fertilizers on spring wheat yield in semi-arid area of western Liaoning Province].

With optimum saturation design, a field experiment was conducted to study the coupling effect of water and fertilizers on spring wheat yield in semiarid area of western Liaoning Province. Regression model shows that water was the most important factor affecting spring wheat yield. Under natural raining and when the upper and the lower limit of irrigation was 360 mm and 45 mm, respectively, N was the most sensitive factor, water was the second, and P was the third. The effects of N, P and water on yield were statistically significant, and met the law of diminishing return. The most economic matching pattern of N, P and water was N 186 kg.hm-2, P 63 kg.hm-2, and water 300 mm. Properly increasing phosphorus fertilizer at the lack of water could strengthen the drought-resistance of spring wheat.

China↗

PubMed2000

[Effect of interaction between water and fertilizer on wheat and maize semiarid region of western Liaoning].

Using 312-D optimum design and quadratic general rotation design, the effect of interaction between water and fertilizer on wheat and maize yields was studied in semiarid region of western Liaoning Province. Reasonable combination of applying N and P fertilizers, irrigation, and mulching corn straws could increase crop yield remarkably, otherwise, it could not only increase cost, but also result in output reduction due to increasing crop stress to water or nutrients. Based on the results of the trials, the effects of the productive factors on crop yield were analyzed. The optimum economical combination of water and fertilizers fitting for local agriculture was put forward, i.e., water 120.2 mm, N 58.5 kg.hm-2, and P2O5 123.0 kg.hm-2 for wheat, and water 173.3 mm, N 256.5 kg.hm-2, P2O5 85.5 kg.hm-2, and straw mulching 8509.5 kg.hm-2 for maize.

Fertilizers↗

PubMed2000

[A primary study on chemical bound forms of copper and zinc in wheat and rape].

Sequential extraction method was used to analyze and distinguish various chemical bound forms of copper and zinc in rape and wheat. The results show that in these two crops, copper was mainly in the form of wate soluble and ethanol soluble, which can be easily transferred in crops. The total content of various chemical bound forms of copper was higher in aboveground part than in underground part, and their content was decreased in the order of water soluble form (W.S. form) > residual form (Re. form) > ethanol soluble form(Eth. S. form) > acid soluble form (A.S. form). Zinc was mainly in the form of acid soluble, which is hard to be transferred in crops. The total content of various chemical bound forms of zinc was lower in aboveground part than in roots, and their content was decreased in the order of A.S. form > Re. form > W.S. form > Eth. S. form. In comparing with copper, a large amount of zinc was enriched in seeds and pods of rape.

Binding Sites↗