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Biomedical subjects

H Z Li

Publications and source records attributed to H Z Li.

At least 19 recordsLinked to original sources
PubMed2005

An analytical approach to the rise velocity of periodic bubble trains in non-Newtonian fluids.

The present study aims at providing insight into the acceleration mechanism of a bubble chain rising in shear-thinning viscoelastic fluids. The experimental investigation by the Particle Image Velocimetry (PIV), birefringence visualisation and rheological simulation shows that two aspects are central to bubble interactions in such media: the stress creation by the passage of bubbles, and their relaxation due to the fluid's memory forming an evanescent corridor of reduced viscosity. Interactions between bubbles were taken into account mainly through a linear superposition of the stress evolution behind each bubble. An analytical approach together with the rheological consideration was developed to compute the rise velocity of a bubble chain in function of the injection period and bubble volume. The model predictions compare satisfactorily with the experimental investigation.

Computer Simulation↗
PubMed2004

Effect of mifepristone on the expression of cytokines in the human Fallopian tube.

Cytokines are believed to play a critical role as mediators between the oviduct and the developing embryo. A synchronous development of embryo and endometrium is essential to successful implantation. It seems to be beneficial for embryo development to rest for some time in the Fallopian tube. Expression of cytokines in the human Fallopian tube and the effect of mifepristone were investigated. Fourteen women with regular menstrual cycles and proven fertility, admitted to the hospital for tubal ligation, were randomly allocated to control or treatment groups. Mifepristone 200 mg was given on day LH+2. Surgery was performed on day LH+3 to LH+5. Biopsies were obtained from the ampullar and isthmic regions of the tubes. Expression of interleukin 8 (IL-8), tumour necrosis factor alpha (TNFalpha), transforming growth factor beta (TGFbeta) and leukaemia inhibitory factor (LIF) was analysed using immunohistochemistry. All cytokines except IL-8 showed the same staining intensity both in the ampullar and isthmic region, while IL-8 was more pronounced in the ampullar region in both epithelial and stromal cells. Exposure to mifepristone made the spatial difference in IL-8 disappear and increased the expression of TNFalpha in the epithelium of the isthmus, but had no effect on the expression of TGFbeta1 or LIF. Changes in cytokine expression in the Fallopian tube are likely to influence embryo development, which could contribute to the contraceptive effect of mifepristone.

Adult↗
PubMed2001

[Significance and application of nuclear matrix protein 22 in detecting bladder cancer].

OBJECTIVE: To investigate the significance of nuclear matrix protein 22 (NMP22) in the detection of bladder cancer. METHODS: The level of NMP22 was measured in the urine of 90 patients (40 patients with bladder cancer and 50 patients with non-bladder cancer) by ELISA and compared with urinic cytology (UC). RESULTS: The level of NMP22 in bladder cancer group was significantly higher than that of control group, and it was not influenced by hematuria. The sensitivity of NMP22 was high, but the specificity was lower than that of UC. CONCLUSION: NMP22 can be used to screen and follow up bladder cancer with high sensitivity.

Adult↗
PubMed2001

[Purification of recombinant hEGF expressed in yeast Pichia pastoris and the study on its characters].

OBJECTIVE: To obtain recombinant human epidermal growth factor(hEGF) that can be used in animal experiments and clinical trial. METHOD: Chemically synthesized hEGF gene was expressed in Yeast Pichia pastoris and the secretory hEGF was purified by Phenysepharose 6 Fast Flow(high sub), Q-sepharose High Performance, and Superdex 30 chromatography, and its characters were studied by respective methods. RESULTS: The purified hEGF doesn't contain pyrogen, endotoxin, or yeast chromosome DNA and the purity reached 98%. The recombinant human EGF has correct molecular weight, pI, N-terminal amino acids sequences, peptide map, ultraviolet spectrum and well-biological activity. CONCLUSION: The purified hEGF is in accord with the requirements for animal experiments and clinical trial which provides the basis of preparing EGF agents for clinical test.

Animals↗
PubMed2000

Histamine excites rat cerebellar Purkinje cells via H2 receptors in vitro.

Recent neuroanatomical studies have revealed a direct hypothalamocerebellar histaminergic pathway. However, the functional significance of the histaminergic fibers in the cerebellum is not yet clear. In this study, the effects of histamine on the firing of cerebellar Purkinje cells (PCs) were investigated in vitro. Histamine predominantly produced excitatory (106/111, 95.5%) and in a few cases inhibitory (5/111, 4.5%) responses in PCs. The histamine-induced excitation was not blocked by perfusing the slice with low Ca2+ high/Mg2+ medium (n = 8), supporting a direct postsynaptic action of histamine. The histamine H2 receptor antagonist ranitidine effectively blocked the excitatory response of PCs to histamine (n = 20), but triprolidine, an H1 receptor antagonist, could not significantly block the histamine-induced excitation, or only very slightly decreased the excitatory effect of histamine on the cells (n = 13). On the other hand, the highly selective H2 receptor agonist dimaprit mimicked the excitatory effect of histamine on PCs and this dimaprit-induced excitation was also blocked by ranitidine (n = 20), but not triprolidine (n = 8). However, the H1 receptor agonists betahistine and 2-thiazolylethylamine did not show any effect on the PCs (n = 9 and 14). These results reveal that histamine excites cerebellar PCs via H2 receptors and suggest that the hypothalamocerebellar histaminergic fibers may play an important role in functional activities of the cerebellum.

Action Potentials↗
PubMed2000

Determination of trace selenium in human plasma and hair with ternary inclusion compound-fluorescent spectrophotometry.

A method for determination of selenium in plasma and hair with ternary inclusion compound-fluorescent spectrophotometry has been developed. The determination of selenium in plasma and hair can be performed directly in aqueous solution. Blood and hair samples were destroyed by oxygen flask combustion. The linear range was 10-500 ng mL-1 for plasma and 10-100 ng mL-1 for hair. Within-day and day-to-day precisions for plasma ranged from 5.4% to 9.3% (n = 7) and from 3.5% to 14.5% (n = 7), respectively. Within-day precisions for hair ranged from 0.6% to 6.2% (n = 7). Recoveries ranged from 91.0% to 97.8% for plasma and from 95.0% to 102.0% for hair. The blood samples from 15 Hans and 20 Uygurs in Xinjiang Uygur automatic region and 23 Hans in Liaoning province were collected and determined. It was indicated that no statistically significant difference in plasma selenium concentration of the Hans between Xinjiang and Liaoning was found (F = 1.36, P > 0.05). However, there were statistically significant differences between the Hans and the Uygurs in Xinjiang (F = 1.01, P < 0.01) and between males and females in the two areas (P < 0.01). There was a low correlation between plasma selenium concentration and hair selenium concentration. The ratio of hair selenium concentration to plasma selenium concentration was 2.17, with a range of 1.63-2.88.

Hair↗
PubMed2000

Defining mental illness and accessing mental health services: perspectives of Asian Canadians.

Asian Canadians consistently underutilize mainstream mental health services. This study investigates how the definition and meaning of mental illness relates to barriers Asian Canadians find in accessing mental health services. Personal interviews were conducted with 60 Asian Canadians in a northern community in the province of British Columbia. Content analyses revealed six themes that defined a mental health problem: (a) feeling a lack of purpose in life, (b) feeling lonely, (c) difficulties understanding and dealing with a new environment, (d) high anxiety levels, (e) descriptions of mental health problems as somatic illnesses, and (f) perceptions of mental illness as serious and potentially not treatable. It was also found that poor English language ability and a lack of understanding of mainstream culture were major barriers to accessing mental health facilities. Findings of this study provided valuable insights concerning Asian immigrants' hesitancy accessing and utilizing mainstream mental health facilities. The many poignant personal anecdotes illustrate that the migration and adaptation processes can be painful and full of anguish. Unless their experiences are better understood and accepted, many Asian Canadians will likely remain outside of the available mainstream mental health facilities.

Adolescent↗
PubMed2000

[A study of the effects of L-arginine in pathogenesis of hypoxic pulmonary hypertension].

AIM: To investigate the role of nitric oxide (NO), nitric oxide synthase (NOS) and endothelin-1 (ET-1) in the pathogenesis of hypoxic pulmonary hypertension and inhibiting effects of L-Arginine. METHODS: 30 rats were divided into 3 groups, normal control group (group NC); Hypoxic group (group HP): exposed to 10% O2 8 h/day, 3 weeks; Hypoxic + L-arginine (group LT): fed L-arginine 200 mg/kg before hypoxia. After exposed to hypoxia 21 days, hemodynamics were measured. Lung speciments were examined by light and electronic microscopes and morphometric analysis. NO, ET-1 levels in lung tissue were measured, the cNOS quantitative in the pulmonary endothelium were examined. RESULTS: In HP group, the mean pulmonary arterial pressure (m PAP), pulmonary vascular resistance (PVR) the percentage of completely muscular coattype medial muscle layer of pulmonary artery in intra-acine and ET-1 level of HP group increased (P < 0.01), but NO and cNOS level decreased (P < 0.01). Examined by electron micrograph, endothelium cells appeared swollen, broken and pealed of, basal lamina parted. The changes above in LT group reversed partly. But the changes above were still several than that of group NC (P < 0.05). CONCLUSION: The structure remodel of pulmonary arteries and endothelium lesion in hypoxia cause m PAP, PVP arising, that are correlated with the levels of ET-1 increasing and NO, cNOS decreasing. For L-arginine can partly supply NO, it may partly reverse the changes of HPH.

Animals↗
PubMed2000

Expression of vascular endothelial growth factor during the early stage of maxillofacial blast injury.

OBJECTIVE: To determine the expression and the change of vascular endothelial growth factor (VEGF) and its acceptor KDR during the early stage of maxillofacial blast injury. To evaluate the effect of VEGF on traumatic wound healing. METHODS: The rabbit model of maxillofacial blast injury was made by KTY-04 blasting cap. The expression of VEGF and KDR in wound tissue was determined by ABC immunohistochemistry of 6 hours, 1 day, 2 days, 3 days, 5 days, and 7 days after injury. The results were compared with preinjury groups. RESULTS: In the wound tissue of the maxillofacial blast injury, the expression of VEGF rose steadily during the first week after the injury. Compared with normal tissue, the wound tissue showed differences by the first day after injury, and showed significant differences by the third day (P < 0.01). The differences reached a peak at the seventh day after injury. The expression of KDR showed no difference within 3 days after injury when compared to normal tissue. Between 5 and 7 days after injury, the protein was more strongly expressed. CONCLUSION: The stage of the VEGF expression at the maxillofacial blast injury site is similar to the angiopoietic stage during would healing, and KDR expression also occurs during that period. VEGF takes part in angiogenic cascades of traumatic wound healing and is produced as an auxiliary action to the regeneration of blood vessels.

Animals↗
PubMed2000

[Role of TNF-alpha and ICAM-1 in pathogenesis of cerebral malaria].

OBJECTIVE: To investigate the role of TNF-alpha and ICAM-1 in the pathogenesis of cerebral malaria. METHODS: Immunohistochemical method and ELISA were employed to examine the expression of ICAM-1 on the brain microvessel endothelium and to detect the production of serum TNF-alpha in P. berghei ANKA strain infected-CBA/J mice. RESULTS: Serum TNF-alpha levels of mice were apparently higher and the ICAM-1 expression was more evident in P. berghei ANKA infected-CBA/J mice than in control groups. rTNF-alpha i.p. injection could enhance the development of CM and the expression of ICAM-1 on brain endothelial cells(EC). CONCLUSION: Excessive production of TNF-alpha may mediate the expression of ICAM-1 on brain EC and hence cause the development of CM.

Animals↗
PubMed1999

[The excitatory effects of histamine on cerebellar cortical Purkinje cells in the rat].

The effects of histamine on Purkinje cells (PCs) in lobule X of cerebellar cortex were investigated in rat cerebellar slices. Histamine elicited PCs' responses predominately excitatory (94.4%, 51/54), only few inhibitory (5.6%, 3/54). The excitatory response could not be abolished by perfusing the slices with low Ca2+/high Mg2+ medium. The excitatory response of PCs to histamine could be blocked by histamine H2 receptor antagonist ranitidine, but not by H1 receptor antagonist triprolidine readily. These results suggest that histamine exerts an excitatory effect on the PCs via H2 receptors. Presumably, hypothalamo-cerebellar histaminergic fibers participate in the regulation of somatic and non-somatic functions of the cerebellum.

Animals↗
PubMed1998

Enzyme immunoassay for a characteristic protein in the animal crude drug lumbricus.

A new method was developed to measure the content of a Lumbricus component in a traditional Chinese medicine (TCM). An antiserum specific to Lumbricus was elicited in a rabbit following immunization with a suspension of Lumbricus fragments. A characteristic antigen protein, 70 kDa, was found in Lumbricus and was purified almost to singleness using a column chromatography series of gel filtration and DEAE-Sepharose. A selected antibody enzyme immunoassay (SAEIA) was developed using the antiserum and the purified 70 kDa protein as a solid-phase antigen. The SAEIA was specific to Lumbricus species, and showed no cross-reaction with any crude drugs other than Lumbricus. This SAEIA detected 70 kDa protein in the amount of 10 ng/ml with excellent reproducibility (coefficient of variation=3.0%) and an EC50 of 0.24 microg/ml. Using this assay, Lumbricus levels were easily determined in a Lumbricus-based TCM Kazecoll, but not in the control Kazecoll (Kakkonto) prepared without Lumbricus. The SAEIA for 70 kDa protein was simple, accurate, reproducible and may provide a general analytical method for the quality control of Lumbricus-based TCMs.

Animals↗
PubMed1997

Application of a licorice root specific protein to a general method for the assay of licorice root components in traditional Chinese medicines.

A new fuzzy immunoassay method generally applied to ten Glycyrrhizae Radix (GR) preparations of four different botanical origins was studied. Four kinds of antisera were elicited in rabbits immunized with GRs of different botanical origins. The presence of the characteristic GR protein (GRP) was shown using Western blot analyses and selected antibody enzyme immunoassay (SAEIA) methods. A GRP was isolated from one of the GR specimens which was selected using SAEIA methods. The isolated GRP was heated to reduce its binding activity to an anti-GR serum. A new fuzzy SAEIA method generally applicable for assay of the extract of the ten GR specimens was developed using heat-treated GRP as the solid-phase antigen. The fuzzy SAEIA method was successfully applied for the detection and quantitative analysis of the GR component contained in traditional Chinese medicines.

Animals↗
PubMed1996

Ras-dependent and Ras-independent activation pathways for the stress-activated-protein-kinase cascade.

We have previously shown that osmotic stress activates both the mitogen-activated protein kinase (MAPK) cascade and the stress-activated protein kinase (SAPK, also known as JNK) cascade in rat fibroblastic 3Y1 cells and rat PC12 cells. Here, we show that treatment of these cells with sodium arsenite, a chemical compound that mimics the effects of heat shock, or anisomycin, a protein synthesis inhibitor, induces activation of SAPKs potently. These chemical compounds also stimulated the activity of SEK1/MKK4/JNKK, SAPK activator, and the activity of MEKK, SEK1 activator. Expression of a dominant negative mutant of Ras blocked the anisomycin-induced activation of SAPK and SEK1, but did not affect markedly the arsenite-induced or heat shock-induced activation in PC12 cells. The osmotic-stress-induced activation of SAPK was insensitive to the expression of a dominant negative Ras, but was partly sensitive to down-regulation of protein kinase C. These results suggest the existence of Ras-dependent and Ras-independent activation pathways for the SAPK cascade triggered by environmental stresses including chemical stress in PC12 cells. Cell staining with a specific anti-SAPK serum showed that SAPKs were present in both the cytoplasm and the nucleus under normal conditions, and became located mainly in the nucleus after osmotic stress or ultraviolet treatment, suggesting the nuclear translocation of SAPKs.

Animals↗
PubMed1995

[Study of the length of the installed gastric tube for children].

The purpose of this study was to find the proper measurement of the length of gastric tube for children preoperatively. The author found that the tube can only reach the cardia of stomach by routine measurement and can not achieve the purpose of gastrointestinal decompression. This study was done to 34 patients. The length of the inserted gastric tube was measured by the distance from the hair border of the middle forehead to the umbilicus. The tube was confirmed to reach the body of stomach during surgery and can reduce gastro-intestinal pressure effectively after operation.

Child↗
PubMed1994

Exploring factors influencing alcohol consumption patterns among Chinese and Caucasians.

Past research on alcohol consumption patterns comparing Chinese and Caucasians indicates that significant group differences exist. Chinese, as a group, consume significantly less alcohol than their Caucasian counterparts. Explanations for these differences have been controversial. Some argue that it is due to cultural differences, whereas others contend that it is because of physiological differences. The present study explores this controversy using a new approach: model testing via path analysis. With a sample size of 178 Canadian Chinese and 161 Caucasian university students, the present study found that in both ethnic groups, cultural norms rather than physical symptoms were a significant predictor of alcohol consumption patterns. This finding strongly suggests that alcohol consumption behavior can be better understood by a social/psychological rather than a biomedical approach. To effect changes in alcohol assumption patterns, it is suggested that cultural interpretations of alcohol use should be examined.

Acculturation↗