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Biomedical subjects

X H Xu

Publications and source records attributed to X H Xu.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Improving effect of NGF by intrahippocampal injection on aging-related memory impairment].

AIM: To study the improving effect of NGF (nerve growth factor) on aging-related memory impairment and its possible mechanism of action. METHODS: After direct intrahippocampal injection of NGF, the spontaneous behavior and the memory retention of aging mice were observed using open field and one-trial passive avoidance test. At the same time, the free [Ca2+] and protein synthesis in hippocampal synaptosomes were measured in vitro by using fluorescence indicator Fura-2/AM and 3H-Leu respectively. RESULTS: Compared with the control, NGF was shown to increase significantly the spontaneous behavior and explorative response in the open field, and improve remarkably the memory consolidation of old mice (P < 0.05). NGF decreased notably the intrasynaptosomal free [Ca2+] in hippocampus. Meanwhile, the incorporation of 3H-Leu into the synaptosomal proteins of hippocampus increased significantly. CONCLUSION: NGF showed an improvement effect against the aging-related memory impairment. A decrease of intrasynaptosomal free [Ca2+] and an increase in protein synthesis may be involved in this effect.

Aging↗
PubMed2000

[Correlation between the age-related memory impairment and the level of free Ca(2+) in brain synaptosomes].

In this study, We investigated the changes in the ability of learning-memory of 12-month- and 18-month-old mice, and the intrasynaptosomal Ca(2+) levels of some mouse brain areas (hippocampus, cerebral cortex, corpus quadrigem and cerebellum) on the basis of our last behavior observation and biochemistry detection. Meanwhile, the intrasynaptosomal Ca(2+) levels of the four brain areas were compared between the mice of impaired and good memory. The main results are as follows. With the increase of age, the ability of learning-memory of mice decreased significantly; and the concentration of the intrasynaptosomal free Ca(2+) (i) in mouse brain areas (except for cerebral cortex) increased markedly, especially in the memory-impaired mice. The results suggest that age-related memory impairment may be associated with the overloading of intrasynaptosomal free Ca(2+) (i).

Aging↗
PubMed1999

[Immunohistochemical study on myocardial acute ischemia reperfusion injury in rats with anti-FOS protein antibody].

To investigate law of FOS protein induced by myocardial ischemia reperfusion (MI/R) in acute period, a model in 20 anaethetized SD rats was established. Rats with normal and ischemia were used as control groups. Specimens were studied immunohistochemically with c-fos antibody. After ischemia 20 minutes, followed by 30 minutes reperfusion, the area of MI/R showed nuclei of myocytes positive staining in cryosection slides. In C2 group, the area showed nuclei of myocytes (37.76% +/- 9.66%) positive staining weakly. In C3 group, nuclei of cardiac myocytes(40.34% +/- 3.32%) was significantly positive. In C4 group it began to attenuate(35.36% +/- 4.81%). The myocardium in normal and ischemic control groups showed negative staining. No changes were seen with HE staining. Our data indicated that immunohistochemical method may reveal acute MI/R injury of ischemia 20 min and reperfusion 30 min with anti-FOS protein staining and there is problely a peak between 60-120 min after reperfusion. It is possible that the method be used to diagnose sudden cardiac death in forensic medicine.

Animals↗
PubMed1999

[Brainstem changes in death from head injury].

The cortex and brainstem changes in death from head injury were observed. There were hemorrhage, edema and neuron necrosis in brain injury group, and also in disputed group of brainstem injury.

Adolescent↗
PubMed1999

[Immunoaffinity purification of specific immunoglobulin from egg yolk].

Immunoaffinity column (Sepharose-4B) was made with bovine serum albumin (BSA) and used to isolate anti-BSA antibody from egg laid by hens which were immunized with BSA. Polyclonal antibody was eluted under different conditions (pH 5.0-2.8) because of its different affinity against antigen. SDS-PAGE and double-immunodiffusion analysis confirmed that antibody isolated from egg yolk was electrophoretically pure and specific. According to the separation aim in this paper, the final elution buffer was 0.1 mol/L glycine-HCl buffer, pH 2.8. The final antibody yield was higher than 90%. As a new development in chromatographic media, POROS has its maximum pressure limit of 21 MPa. It has been widely used because of its high performance, high flow and large capacity. The sugar residue of the antibody was then oxidized and coupled to the hydrazide activated POROS HY. Pure targeted protein (BSA) was obtained through the POROS HY column. The tendency of specific antibody production was investigated during the immunization period. The amount of specific antibody has increased obviously after boost immunization.

Chromatography, Affinity↗
PubMed1998

Long-range electrostatic trapping of single-protein molecules at a liquid-solid interface.

The motion of single, dye-labeled protein molecules was monitored at various pH and ionic strengths within the 180-nanometer-thick evanescent-field layer at a fused-silica surface. Below the isoelectric point, molecules partitioning into the excitation region increased in number but maintained a random spatial distribution, implying that surface charge can influence the charged protein at distances beyond that of the electrical double-layer thickness. The residence times of the molecules in the interfacial layer also increased below the isoelectric point. However, immobilization on the solid surface for extended periods was not observed. Histograms of residence times exhibit nearly identical asymmetry as the corresponding elution peaks in capillary electrophoresis. These results are a direct verification of the statistical theory of chromatography at the single-molecule level, with the caveat that long-range trapping rather than adsorption is the dominant mechanism.

Chemical Phenomena↗
PubMed1998

Effect of catecholamic acid on detoxication and distribution of NiCl2 in mice and rats.

AIM: To study the effect of catecholamic acid (CBMIDA) on detoxication of NiCl2. METHODS: Mice and rats were injected s.c. or i.m. CBMIDA immediately after i.p. NiCl2. Each mouse was injected i.p. CBMIDA after i.v. 63NiCl2 185 kBq, and radioactivities of various tissues were measured with liquid scintillation counter at 24 h. The localization of 63Ni was shown by the whole-body autoradiography. RESULTS: CBMIDA s.c. 0.5-1.5 g.kg-1 markedly reduced the mortality from acute poisoning of i.p. NiCl2 500 mg.kg-1. After i.p. NiCl2 in mice, the LD50 was 82.7 mg.kg-1. Mice were injected s.c. CBMIDA 1.5 or 2.5 g.kg-1 after Ni poisoning, the LD50 of NiCl2 were raised to 789 or 820 mg.kg-1, respectively. The LD50 of NiCl2 was 39 mg.kg-1 in rat. If CBMIDA was injected i.m. 0.5 g.kg-1 after i.p. NiCl2, the LD50 was 332 mg.kg-1. CBMIDA 1.5 g.kg-1 i.m. after i.v. 63NiCl2, decreased the contents of 63Ni in blood and lung of mice vs control mice at 24 h. The contents of 63Ni in brain, heart, spleen, and kidney were similar to those of the control mice. The content of 63Ni in bone was more than the control. The excretions of 63Ni through urine and feces were not increased by CBMIDA at 24 h. The whole-body autoradiography showed that the radioactivity was highly localized in the kidney, lung, and Harder's gland. There was a moderate level of 63Ni in the liver, bone, skin, and blood. A pronounced accumulation occurred in the bone. There was a marked reduction of 63Ni in the lung, skin, liver, and blood after i.p. CBMIDA. CONCLUSION: The CBMIDA markedly raised the survival rate of nickel-poisoned mice and rats, and decreased 63Ni levels in lung and blood.

Animals↗
PubMed1997

Chromosome 19 single-locus and multilocus haplotype associations with multiple sclerosis. Evidence of a new susceptibility locus in Caucasian and Chinese patients.

CONTEXT: Susceptibility to multiple sclerosis (MS) involves a genetically complex autoimmune component. However, except for genes in the HLA system, specific susceptibility loci are unknown or unconfirmed. OBJECTIVE: To investigate several loci spanning 3 candidate regions for a role in multiple sclerosis (MS) susceptibility in 2 ethnic groups using both single-locus and haplotype analyses. The 3 regions include HLA on chromosome 6p21.3, APOE on chromosome 19ql 3.2, and MBP(myelin basic protein) on chromosome 18q23. DESIGN: Case-control association testing. SUBJECTS: A total of 120 Caucasian patients with MS and 107 unrelated control individuals from California, and 32 patients and 32 unrelated control individuals from Beijing, China. All patients with MS were diagnosed as having clinically definite disease according to published criteria. MAIN OUTCOME MEASURES: Chi2 Testing of loci and individual alleles and haplotypes. Haplotype frequencies were estimated with standard maximum likelihood methods. RESULTS: The HLA effect is due to the class II DR2 haplotype, DRB1*1501-DQA1*0102-DRB1*0602; contributions to MS susceptibility from additional DRB1-DQB1 alleles or other HLA region loci were not observed. Variation within the MBP locus on chromosome 18q23 showed no effect in MS. The distribution of haplotypes from 5 loci within the chromosome 19q13.2 region, including D19S178, D19S574, APOE, APOC2, and D19S219, differed between patient and control samples. D19S574 showed a significant effect (P=.015) in Caucasian patients with MS due to the increased frequency of a single allele (P=.002). The APOE variation, prominent in other neurological diseases, showed no influence on MS susceptibility, despite its location within the chromosome 19q13.2 region. Interaction effects between DR2 and chromosome 19q13.2 or MBP in MS susceptibility were not apparent. CONCLUSIONS: The significant chromosome 19q13.2 single-locus and multilocus haplotype associations with MS in Caucasian and Chinese patient samples indicate an effect from a nearby disease susceptibility locus. These initial observations are an encouraging step toward the description of non-HLA genetic susceptibility to MS.

Alleles↗
PubMed1997

Direct measurement of single-molecule diffusion and photodecomposition in free solution.

Continuous monitoring of submillisecond free-solution dynamics of individual rhodamine-6G molecules and 30-base single-stranded DNA tagged with rhodamine was achieved. Fluorescence images were recorded from the same set of isolated molecules excited either through the evanescent field at the quartz-liquid interface or as a thin layer of solution defined by micron-sized wires, giving diffraction-limited resolution of inter-connected attoliter volume elements. The single-molecule diffusion coefficients were smaller and the unimolecular photodecomposition lifetimes were longer for the dye-DNA covalent complex as compared with those of the dye molecule itself. Unlike bulk studies, stochastic behavior was found for individual molecules of each type, and smaller diffusion coefficients were observed.

DNA, Single-Stranded↗
PubMed1997

Quantitative stereological studies of a 'selection' protocol of hepatocarcinogenesis following initiation in neonatal male and female rats.

A modified initiation-selection procedure for neonatal male and female rat hepatocarcinogenesis were examined utilizing the methods of quantitative stereology. In this study, diethylnitrosamine (10 mg DEN/kg) was given a few days after birth. At weaning, the rats were fed 0.02% 2-acetylaminofluorene (AAF) for 2 weeks with a mitotic stimulus [70% partial hepatectomy (PH)] after 1 week on the diet. Quantitative stereological analyses in conjunction with the use of several enzyme markers were used to determine the number and volume of altered hepatic foci (AHF) detected at 1 week, 3 months and 7 months after the selection procedure. This format resulted in an equivalent number of AHF in male and female rats. The AHF were three times larger in males than in females 1 week after discontinuation of AAF administration. Three months after the selection procedure, the number of AHF had decreased by at least a third and their volume percentage was the same in male and female rats. After 7 months, the number and volume fraction of detectable AHF in females were comparable to those which had been observed at 1 week after selection. In the male, the number but not the volume fraction were similar at 7 months compared with 1 week after selection. Both initiation with DEN and selection with AAF/PH contribute independently to the total population of AHF in male and female rats. At least half of the AHF detected 7 months after the selection protocol were due to DEN administration alone. Rats receiving only the AAF/PH selection exhibited one third of the number of AHF observed with the complete protocol. Administration of a non-necrogenic dose of DEN to neonatal rats when coupled with the AAF/PH selection procedure resulted in a significant promotion of the growth of initiated hepatocytes at 1 week, 3 months or 7 months after the selection procedure. These studies demonstrated that (i) the number of AHF detected after a non-necrogenic dose of DEN during the first week of life with subsequent AAF/PH selection after weaning decreases within the first 3 months after the selection procedure, but can re-develop with a promotion stimulus; (ii) the AAF/PH selection procedure itself may initiate hepatocytes in the absence of DEN administration; (iii) the AAF/PH selection procedure is equally effective with respect to the number of AHF observed after phenobarbital promotion in weaning male and female rats initiated near birth.

2-Acetylaminofluorene↗
PubMed1997

[Regulation of NGF on intra-synaptosomal free [Ca2+]i in mouse brain].

In the present study, the influence of direct intrahippocampal injection of NGF (nerve growth factor) on synaptosomal free [Ca2+]i in 1-month-old and 18-month-old mice was observed. The regulation of NGF on synaptosomal free [Ca2+]i in vitro was also investigated. The synaptosomal free [Ca2+]i in the main brain regions (cerebral cortex, hippocampus, cerebellum, diencephalon) of these mice was measured by fluorescent probe Fura-2 of Ca2+ indicator and an AR-CM-MIC cation measurement system. The results are as follows: (1) NGF showed no detectable effect on hippocampal intrasynaptosomal free [Ca2+]i in 1-month-old mice, but appropriate dose of NGF was shown to markedly reduce [Ca2+]i in 18-month-old mice. (2) Under the condition of low [Ca2+]i level caused by the drug, NGF was found to increase [Ca2+]i; conversely, was reduced [Ca2+]i when intracellular Ca2+ was overloaded. These results suggest that NGF has dual regulation on Ca2+ level in brain and this might be an important mechanism for its action in improving memory lesion, in aged person.

Aging↗
PubMed1997

[Effect of theo-polyphenols on oxygen free radicals and hemorrheology in patients with essential hypertension].

OBJECTIVE: To observe the effect of theo-polyphenols (TP) on oxygen free radicals and hemorrheology in patients with essential hypertension. METHODS: Hemorheology as well as oxygen free radical of 38 patients were determined before and after TP treatment. RESULTS: TP markedly increased RBC-SOD activity, reduced the level of serum MDA, the whole blood viscosity, plasma viscosity and the level of plasma fibrinogen. The efficacy of TP was higher than that of aspirin. CONCLUSION: The TP had remarkable effects of anti-oxygen free radicals, and could improve hemorheology.

Aged↗
PubMed1995

Comparison of effects of MPTCP and PTCP ceramics implanted for the treatment of bone defects in rabbits.

The magnetic porous tricalcium phosphate (MPTCP) and porous tricalcium phosphate (PTCP) ceramic cylinders were implanted into right and left bone defects of rabbits' radii in order to determine the utility of the MPTCP ceramics. Based on naked eye inspection, light and scanning electron microphotography, roentgenography, quantitative histological measurement of new bone formation and anti-break test for a period of 5 months. The results showed that the two kinds of ceramics were biocompatible with human tissue. MPTCP ceramics could induce more new bone formation than PTCP ceramics. Treatment of fractures with synthetic calcium phosphate ceramics and magnetic fields were discussed.

Animals↗
PubMed1994

[Effect of dimercaptosuccinic acid per os on distribution and excretion of 210Pb and 203Hg in mice].

Sodium dimercaptosuccinate (Na-DMS) ip 1 g.kg-1, dimercaptosuccinic acid (DMSA) ig 1 g.kg-1, DMSA ig 1 g.kg-1 with NaHCO3 or Na-citrate ig 3 g.kg-1 was given to mice, separately. It enhanced the excretion of 210Pb in urine about 3.4, 3.8, 3.6, and 2.3 times vs control, respectively within 24 h. It enhanced the excretion of 203Hg in urine about 2.4, 2.3, 3.3, and 2.7 times, respectively within 24 h. Fecal excretion was not significantly elevated vs control. Tissue radioactivities showed a remarkable decrease in the levels of 210Pb and 203Hg in most organs, but DMSA increase the 210Pb content in kidney. The therapeutic effect of ig DMSA was similar to that of ip sodium dimercaptosuccinate.

Animals↗
PubMed1994

[A study on HLA-Dr expression of brain tumor cells and mononuclear cell subsets infiltrating in these tumors].

Fourty-four primary brain tumors were studied by immunohistochemistry. 29 (67.2%) expressed HLA-Dr. The incidence and number of tumor cells positive for HLA-Dr correlated with the histological type of brain tumor and increased with the degree of malignancy. The mononuclear cells infiltrating in these tumors were mostly CD45ROT cells and macrophages. The former consisted mainly of CD4 and CD8 subsets. The numbers of CD45RO+ and CD8+ T cells in HLA-Dr-group were more than any of the HLA-Dr+, +2, +3 groups. The numbers of CD4 subset and macrophages were not affected by the level of HLA-Dr expression. These results suggest that the HLA-Dr expressed by brain tumor cells selectively inhibit CD8 subset which participates in immunoreaction against brain tumors in situ.

Adolescent↗
PubMed1994

[Protective effects of ginsenoside on myocardiac ischemic and reperfusion injuries].

Thirty mitral valvular surgical patients were randomly divided into three groups for study of protective effects of Ginsenoside on myocardiac ischemic and reperfusion injuries. In GI, 11 patients (controls), no Ginsenoside was used, in GII, 11, Ginsenoside in total was added into the cardioplegic solusion made in our hospital, and in GIII, 8, instead of Ginsenoside in total Ginsenoside Rb was added. During operation comparative studies were made of pre- and postoperative cardiac functions with intraoperative transesophageal echocardiography and ultrastructures of myocardiac cells with electromicroscopy. We conclude that both Ginsenoside in total and Ginsenoside Rb have protective effects on myocardiac ischemic and reperfusion injuries in open heart surgery, and the effect of Ginsenoside in total is even better than that of Ginsenoside Rb.

Cardioplegic Solutions↗
PubMed1993

[Effects of dimercaptosuccinic acid per os on copper excretion in rat].

After dimercaptosuccinic acid (DMSA) was given intragastrically by gavage (ig) 0, 250, or 500 mg.kg-1 following in CuSO4 30 mg.kg-1 daily x 3 d in rats, the Cu contents of serum increased markedly within 1-12 h. When ig DMSA daily x 3 d, the excretion of Cu in urine per 24 h in the treated group was greatly promoted vs the control (P < 0.01), that in the 250 or 500 mg.kg-1 group were enhanced 2.4-3.8 and 5.8-7.8 times, respectively. That the excretion of Cu was increased in bile but not in feces suggested the plausible existence an enterohepatic circulation.

Animals↗