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Biomedical subjects

X Han

Publications and source records attributed to X Han.

At least 73 records · Page 4Linked to original sources
PubMed2001

[Effect of rare earth elements on the seedling ratio of crops].

The effects of rare earth elements(REEs) on the relative seedling ratio of three crops(rice, rape and soybean) in three soil(red soil, yellow fluvo-aquic soil and yellow cinnamon soil) were studied according to OECD method, and the LC50 were obtained. Toxicity effect of REEs on rice was minimum among the crops tested. The toxicity on crops in yellow cinnamon soil was lower, whereas on soybean in yellow fluvo-aquic soil and on rape in red earth were higher.

Crops, Agricultural↗
PubMed2001

[Detection of BCL2 translocation in an interphase neucleus using fluorescence in situ hybridization strategy].

OBJECTIVE: To establish a specific method to diagnose non-Hodgkin's lymphoma in clinic. METHODS: Fluorescence in situ hybridization (FISH) strategy capable of detecting t(14;18)(q32;q21) chromosome translocation in an interphase nucleus was developed using a YAC clone containing the BCL2 gene and a phage clone containing IgHC(mu) region as probes. In the SU-DHL-6 cells, the translocated BCL2 allele (red) is overlapped by one of the green signals from IgH phage probe, while in normal lymphocytes the least distance of the hybridization signals from two different probes was either equal or larger than one-tenth of the diameter of a nucleus. RESULTS: Based on the relative position of the signals from BCL2 and IgH probes the BCL2 translocation can be clearly detected in an interphase nucleus. The metaphase number and quality in samples, which could significantly restrict the reliability of cytogenetic analysis, can be ignored here. CONCLUSION: This method shows a potentiality in clinical diagnosis of non-Hodgkin's lymphoma because of its objectivity, reliability and simplicity.

Cell Nucleus↗
PubMed2001

[A pilot study in treatment of systemic lupus erythematosus by autologous bone marrow transplant].

OBJECTIVE: To explore the clinical effect for treatment of SLE by autologous bone marrow transplantation(ABMT). METHODS: Three patients with refractory SLE were chosen. BM stem cells were harvested from the posterior superior iliac crests under epidural anesthesia and preserved in 4 degrees C. BM stem cells were reinfused after conditioned by CTX (120 mg/kg) and malphalan (140 mg/m(2)) or VP-16 (1.0 g/m(2)). G-CSF was used to help hematopoietic and immunologic reconstitution. RESULTS: These three patients had clinical remission after transplantation; the levels of immunoglobulins declined and complements rose up. Most of the auto-antibodies turned negative. Skin pathology in case 2 showed that the former tissue injury alleviated or disappeared. Moreover, myocardial hypertrophy and pericardial effusion also disappeared. CONCLUSIONS: (1) ABMT is obviously effective for SLE. The duration of remission remains to be decided in long-term follow up. (2) Mechanisms of improvement are possibly related to decrease of immunologic pathological cells in tissues after conditioning, reduction of the level of immunoglobulins and drop of the quantity of auto-antibodies.

Adolescent↗
PubMed2001

[Clinical pathological study of lingual squamous cell carcinoma].

OBJECTIVE: To investigate the pathological characteristics of lingual squamous cell carcinoma of younger patients under 40 years old. METHODS: Routine histological examination and immunohistochemistry. Carcinoma tissues from patients over 70 years old were used as control. RESULTS: In younger patients the grade II carcinoma was more common; tumor tissue was more invasive and there was more lymphnode metastasis than in old patients. Stronger p53 expression and weaker CK13 staining were more seen in young patients than old. CONCLUSION: The lingual squamous cell carcinoma of young patients may be more aggressive than of old patients.

Adult↗
PubMed2001

[Changes of crop yields and soil fertility under long-term application of fertilizer and recycled nutrients in manure on a black soil].

The results from a field experiment over thirteen years on a black soil in Northeast China indicated that nitrogen fertilizer increased crop yields by 724 kg.hm-2 per year on average, with an increase rate of 27.5% and about 9.4 kg increased yield from 1 kg applied N. In the early stage, the crop yields almost gave no response to phosphorus fertilizer, owing to the high level of soil available phosphorus at the beginning of the experiment. The average increase of crop yields by phosphorus in thirteen years was only 241 kg.hm-2 per year, with an increase rate of 7%, about 12.7 kg increased yield from 1 kg applied P. Annual application of recycled pig manure made by 80% of harvested grain fed to pigs and the stolks as bedding materials could increase crop yields by 268, 258 and 255 kg.hm-2 per year with an increase rate of 9.8%, 7.6% and 7.0%, based on no fertilizer, with N and with P and N, respectively. There was a trend that the effect of recycled manure on crop yield was gradually increased during the period of experiment, implying the existence of accumulative residual effect from the manure.

Agriculture↗
PubMed2001

[Genetic subtyping of HIV-1 in Liaoning province of China].

OBJECTIVE: To study the prevalence of HIV-1 in Liaoning province of China. METHODS: Nuclear acids were extracted from blood samples of 16 HIV-1 infected individuals collected locally in Liaoning province of China from Jun. 1997 to Dec. 2000. The 0.7 kb or 1.2 kb segments of HIV-1 env gene were amplified using nested-PCR and the HIV-1 genetic subtypes were then assayed by heteroduplex mobility assay. RESULTS: Fifteen of 16 samples were positive by PCR amplification of HIV-1 env region and samples were found to be genetic subtype A,B',C,E. The proportion due to sexual transmission in all HIV infection was 31.25% (5/15), among which subtype B' (3/5) was the majority. A man who returned from Africa together with his spouse both had type A (2/5) infection. Intravenous drug users (IDUs) took up 31.25% (5/15) of all the HIV infections. Subtype C (2/4) and E were predominant among intravenous drug users. However, there was one IDU with subtype B or E. Nearly all blood recipients and blood donors were B' (4/5) except one with C. CONCLUSION: There have been several subtypes of HIV-1 existed in Liaoning province, demonstrating the complexity of HIV epidemology in Liaoning province and the difficulty conducting prevention and treatment.

Acquired Immunodeficiency Syndrome↗
PubMed2001

[Effects of zinc deficiency on the distribution of elements in the tissue of pregnant rats and their fetuses].

The influence of zinc(Zn) deficiency on the distribution of elements in tissues of pregnant rats and their fetuses was investigated. Pregnant Wistar rats were divided into zinc deficiency (ZD), pair-fed(PF), zinc supplement (ZS) and control (C) groups. ZD rats were fed for 21 days a zinc deficient (0.7 mg/kg) diet and other rats were fed a similar diet supplemented with zinc (100 mg/kg). On the 21st day of gestation, blood was drawn from heart, laparotomy was performed, and liver, spleen, kidney, placentas, fetuses were removed for analysing on zinc, copper (Cu), iron (Fe), manganese (Mn) and calcium (Ca). The results showed that the element levels in blood, organs and fetuses from ZD rats were significantly lower than those from ZS and C rats. Furthermore, the levels of Cu, Fe, Mn in blood, liver, spleen, kidney of ZD rats were significantly lower than those of PF rats. It suggests that there are some coordination relationships in intestinal absorption and tissue distribution between Zn and other elements, and the decrease of elements in the body does not mainly result from the reduction of dietary intake caused by zinc deficiency. The Fe content in placentas and Fe, Ca content in fetuses of ZD rats showed a significant increase as compared with those of rats in other groups. There may be a competitive mechanism on the transportation of Zn and Fe in the placenta of rats. In brief, the distribution of minerals in maternal tissues induced by zinc deficiency might be different from those in fetuses.

Animals↗
PubMed2001

[Biological assessment of sintered titanium alloy for dental crown and bridge by means of slip casting].

OBJECTIVE: To evaluate the biological safety of sintered titanium alloy for dental crown and bridge, and provide a sound scientific basis for dental clinical practice. METHODS: A series of tests, including acute toxicity test, cytotoxity test (agar overlay), sensitization test, oral mucous membrane irritation test, haemolysis test and micronucleus test were conducted to examine the dental crown/bridge-used titanium alloy which is processed with vacuum-sintered powder metallurgy. RESULTS: The haemolysis rate of this material was 2.21% (less than 5%), an index of good blood compatibility. Cytotoxic effect was not observed in cell culture, nor was toxic effect observed in mouse toxicity test. Local mucous membrane irritation reaction was not found. No potential mutagenicity of this material was noted. CONCLUSION: Dental crown/bridge-used titanium alloy material is of reliable was noted biological safety in dental clinical application.

Animals↗
PubMed2000

pH-dependent self-association of influenza hemagglutinin fusion peptides in lipid bilayers.

We have recently designed a host-guest peptide system that allows us to quantitatively measure the energetics of interaction of viral fusion peptides with lipid bilayers. Here, we show that fusion peptides of influenza hemagglutinin reversibly associate with one another at membrane surfaces above critical surface concentrations, which range from one to five peptides per 1000 lipids in the systems that we investigated. It is further demonstrated by using circular dichroism and Fourier transform infrared spectroscopy that monomeric peptides insert into the bilayers in a predominantly alpha-helical conformation, whereas self-associated fusion peptides adopt predominantly antiparallel beta-sheet structures at the membrane surface. The two forms are readily interconvertible and the equilibrium between them is determined by the pH and ionic strength of the surrounding solution. Lowering the pH favors the monomeric alpha-helical conformation, whereas increasing the ionic strength shifts the equilibrium towards the membrane-associated beta-aggregates. The binding data are interpreted in terms of a cooperative binding model that yields free energies of insertion and free energies of self-association for each of the peptides studied at pH 7.4 and pH 5. At pH 5 and 35 mM ionic strength, the insertion energy of the 20 residue influenza hemagglutinin fusion peptide is -7.2 kcal/mol and the self-association energy is -1.9 kcal/mol. We propose that self-association of fusion peptides could be a major driving force for recruiting a small number of hemagglutinin trimers into a fusion site.

Amino Acid Sequence↗
PubMed2000

CD47, a ligand for the macrophage fusion receptor, participates in macrophage multinucleation.

The macrophage fusion receptor (MFR), also called P84/BIT/SIRPalpha/SHPS-1, is a transmembrane glycoprotein that belongs to the superfamily of immunoglobulins. Previously, we showed that MFR expression is highly induced at the onset of fusion in macrophages, and that MFR appears to play a role in macrophage-macrophage adhesion/fusion leading to multinucleation. The recent finding that IAP/CD47 acts as a ligand for MFR led us to hypothesize that it interacts with CD47 at the onset of cell-cell fusion. CD47 is a transmembrane glycoprotein, which, like MFR, belongs to the superfamily of immunoglobulins. We show that macrophages express the hemopoietic form of CD47, the expression of which is induced at the onset of fusion, but to a lower level than MFR. A glutathione S-transferase CD47 fusion protein engineered to contain the extracellular domain of CD47, binds macrophages, associates with MFR, and prevents multinucleation. CD47 and MFR associate via their amino-terminal immunoglobulin variable domain. Of the nine monoclonal antibodies raised against the extracellular domain of CD47, three block fusion, as well as MFR-CD47 interaction, whereas the others have no effect. Together, these data suggest that CD47 is involved in macrophage multinucleation by virtue of interacting with MFR during adhesion/fusion.

Animals↗
PubMed2000

A host-guest system to study structure-function relationships of membrane fusion peptides.

We designed a host-guest fusion peptide system, which is completely soluble in water and has a high affinity for biological and lipid model membranes. The guest sequences are those of the fusion peptides of influenza hemagglutinin, which are solubilized by a highly charged unstructured C-terminal host sequence. These peptides partition to the surface of negatively charged liposomes or erythrocytes and elicit membrane fusion or hemolysis. They undergo a conformational change from random coil to an obliquely inserted ( approximately 33 degrees from the surface) alpha-helix on binding to model membranes. Partition coefficients for membrane insertion were measured for influenza fusion peptides of increasing lengths (n = 8, 13, 16, and 20). The hydrophobic contribution to the free energy of binding of the 20-residue fusion peptide at pH 5.0 is -7.6 kcal/mol (1 cal = 4.18 J). This energy is sufficient to stabilize a "stalk" intermediate if a typical number of fusion peptides assemble at the site of membrane fusion. The fusion activity of the fusion peptides increases with each increment in length, and this increase strictly correlates with the hydrophobic binding energy and the angle of insertion.

Amino Acid Sequence↗
PubMed2000

Diabetes-induced changes in specific lipid molecular species in rat myocardium.

Intrinsic cardiac dysfunction during the diabetic state has been causally linked to changes in myocardial lipid metabolism. However, the precise alterations in the molecular species of myocardial polar and non-polar lipids during the diabetic state and their responses to insulin have not been investigated. Herein we demonstrate four specific alterations in rat myocardial lipid molecular species after induction of the diabetic state by streptozotocin treatment: (i) a massive remodelling of triacylglycerol molecular species including a >5-fold increase in tripalmitin mass and a 60% decrease in polyunsaturated triacylglycerol molecular species mass (i.e. triacylglycerols containing at least one acyl residue with more than two double bonds); (ii) a 46% increase in myocardial phosphatidylinositol mass; (iii) a 44% increase in myocardial plasmenylethanolamine mass and (iv) a 22% decrease in 1-stearoyl-2-arachidonoyl phosphatidylethanolamine content. Each of the changes in phospholipid classes, subclasses and individual molecular species were prevented by insulin treatment after induction of the diabetic state. In sharp contrast, the alterations in triacylglycerol molecular species were not preventable by peripheral insulin treatment after induction of the diabetic state. These results segregate diabetes-induced alterations in myocardial lipid metabolism into changes that can be remedied or not by routine peripheral insulin treatment and suggest that peripheral insulin therapy alone may not be sufficient to correct all of the metabolic alterations present in diabetic myocardium.

Animals↗
PubMed2000

Characterization of the protein Z-dependent protease inhibitor.

Protein Z-dependent protease inhibitor (ZPI) is a 72-kd member of the serpin superfamily of proteinase inhibitors that produces rapid inhibition of factor Xa in the presence of protein Z (PZ), procoagulant phospholipids, and Ca(++) (t(1/2) less than 10 seconds). The rate of factor Xa inhibition by ZPI is reduced more than 1000-fold in the absence of PZ. The factor Xa-ZPI complex is not stable to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but is detectable by alkaline-polyacrylamide gel electrophoresis. The combination of PZ and ZPI dramatically delays the initiation and reduces the ultimate rate of thrombin generation in mixtures containing prothrombin, factor V, phospholipids, and Ca(++). In similar mixtures containing factor Va, however, PZ and ZPI do not inhibit thrombin generation. Thus, the major effect of PZ and ZPI is to dampen the coagulation response prior to the formation of the prothrombinase complex. Besides factor Xa, ZPI also inhibits factor XIa in the absence of PZ, phospholipids, and Ca(++). Heparin (0.2 U/mL) enhances the rate (t(1/2) = 25 seconds vs 50 seconds) and the extent (99% vs 93% at 30 minutes) of factor XIa inhibition by ZPI. During its inhibitory interaction with factor Xa and factor XIa, ZPI is proteolytically cleaved with the release of a 4.2-kd peptide. The N-terminal amino acid sequence of this peptide (SMPPVIKVDRPF) establishes Y387 as the P(1) residue at the reactive center of ZPI. ZPI activity is consumed during the in vitro coagulation of plasma through a proteolytic process that involves the actions of factor Xa with PZ and factor XIa.

Blood Coagulation↗
PubMed2000

Duration of viremia in hepatitis A virus infection.

The duration of viremia and time course for development of IgM antibodies were determined prospectively in natural and experimental hepatitis A virus (HAV) infection. Serial serum samples from HAV-infected men (n=13) and experimentally infected chimpanzees (n=5) were examined by nested reverse-transcriptase polymerase chain reaction analysis to detect HAV RNA and by ELISA to detect IgM antibodies to HAV. Among infected humans, HAV RNA was detected an average of 17 days before the alanine aminotransferase peak, and viremia persisted for an average of 79 days after the liver enzyme peak. The average duration of viremia was 95 days (range, 36-391 days). Results were similar in chimpanzees. In addition, HAV RNA was detected in serum of humans and chimpanzees several days before IgM antibodies to HAV were detected. These results indicate that adults with HAV infection are viremic for as long as 30 days before the onset of symptoms and that the duration of viremia may be longer than previously described.

Animals↗
PubMed2000

Structure-based discovery of an organic compound that binds Bcl-2 protein and induces apoptosis of tumor cells.

Bcl-2 and related proteins are key regulators of apoptosis or programmed cell death implicated in human disease including cancer. We recently showed that cell-permeable Bcl-2 binding peptides could induce apoptosis of human myeloid leukemia in vitro and suppress its growth in severe combined immunodeficient mice. Here we report the discovery of HA14-1, a small molecule (molecular weight = 409) and nonpeptidic ligand of a Bcl-2 surface pocket, by using a computer screening strategy based on the predicted structure of Bcl-2 protein. In vitro binding studies demonstrated the interaction of HA14-1 with this Bcl-2 surface pocket that is essential for Bcl-2 biological function. HA14-1 effectively induced apoptosis of human acute myeloid leukemia (HL-60) cells overexpressing Bcl-2 protein that was associated with the decrease in mitochondrial membrane potential and activation of caspase-9 followed by caspase-3. Cytokine response modifier A, a potent inhibitor of Fas-mediated apoptosis, did not block apoptosis induced by HA14-1. Whereas HA14-1 strongly induced the death of NIH 3T3 (Apaf-1(+/+)) cells, it had little apoptotic effect on Apaf-1-deficient (Apaf-1(-/-)) mouse embryonic fibroblast cells. These data are consistent with a mechanism by which HA14-1 induces the activation of Apaf-1 and caspases, possibly by binding to Bcl-2 protein and inhibiting its function. The discovery of this cell-permeable molecule provides a chemical probe to study Bcl-2-regulated apoptotic pathways in vivo and could lead to the development of new therapeutic agents.

Animals↗