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Biomedical subjects

X Han

Publications and source records attributed to X Han.

At least 37 records · Page 2Linked to original sources
PubMed2001

Prevalence of tick-borne encephalitis virus in Ixodes ricinus ticks in Finland.

Approximately 20 cases of tick-borne encephalitis (TBE) occur annually in Finland. The known endemic areas are situated mainly in the archipelago and coastal regions of Finland, with highest incidence in Aland islands. Ixodes ricinus panels collected in 1996-1997 from two endemic areas were screened for the presence of RNA. Two distinct RT-PCR methods were applied, and were shown to have an approximate detection limit of 10 focus forming doses (FFD)/100 microl. One out of 20 pools (a total of 139 ticks) from Helsinki Isosaari Island and one out of 48 pools (a total of 450 ticks) from Aland were positive with both methods, whereas the remaining pools were negative. The observed overall frequency (0.34%) in ticks in endemic areas of Finland, was similar to the low incidence found by virus isolation in mice in the 1960s (0.5%). Viral RNA was detectable in a diluted sample representing 0.005% of a positive pool of ten nymphs suggesting that the viral RNA load within an infected tick pool was approximately equivalent to 20,000-200,000 FFD. Sequence analysis did not show geographical clustering of the Finnish strains, suggesting an independent emergence of different TBE foci from the south. TBE virus RNA positive ticks were not found in I. ricinus panels consisting of 130 pools (726 ticks) from Helsinki city parks or 41 pools (197 ticks) from Võrmsi Island in Estonia.

Animals↗
PubMed2001

A study on the prevention and treatment of myopia with nacre on chicks.

The contents of mineral elements and amino acids in the hydrolysate of the traditional Chinese mineral medicine nacre have been determined. It has long since been proved by the practice of doctors of traditional Chinese medicine that pearl can be used to treat eye diseases. Based on such an understanding, a study is made of the influence of the said medicine on the incidence of myopia. First a form-sense-deprived model (FDM) for chicks is developed and the effect of the said medicine on the elongation of axis oculi is determined with an Abbe's comparator and an A-mode ultrasound instrument. The activity of superoxide dismutase (SOD), nitric oxide synthetase (NOS), and the content of nitric oxide (NO) in the retino-pigmental epithelium choroid homogenate are also analysed. The role of the said traditional Chinese mineral medicine in preventing and treating myopia is explained with respect to the above findings. The results obtained will provide a basis for using nacre, a traditional Chinese mineral medicine, to prevent and treat myopia.

Amino Acids↗
PubMed2001

Vascular smooth muscle cells of recipient origin mediate intimal expansion after aortic allotransplantation in mice.

Intimal expansion by vascular smooth muscle cells (SMCs) is a characteristic feature of graft vascular disease. Whether graft intimal SMCs arise from donor or recipient tissue is not well established but has important pathogenetic implications. We examined for the presence of male cells in the expanded intima of sex-mismatched mouse aortic allografts (C57BL/6-to-BALB/c) at 30 or 60 days after transplant by in situ hybridization using a Y-chromosome probe. Study groups included male-to-female allografts, female-to-male allografts, and female-to-female allografts in recipients previously engrafted with male bone marrow. Although intimal expansion developed in all allografts, male-to-female allografts lacked Y-chromosome-positive intimal cells. In contrast, such cells were abundant in female-to-male allografts and most of these cells co-labeled for smooth muscle alpha-actin by immunostain. Female-to-female allografts in recipients with male bone marrow showed a limited number of intimal Y-chromosome-positive cells. However, none of these clearly co-labeled for smooth muscle alpha-actin and their numbers declined throughout time, consistent with graft-infiltrating inflammatory cells. We conclude that intimal expansion of mouse aortic allografts is mediated by SMCs that originated from the recipient. There was little evidence of their derivation from the bone marrow, suggesting instead the adjacent host aorta as the primary source of intimal SMCs.

Animals↗
PubMed2001

Prevalence and clinical characteristics of mitochondrial tRNAleu(UUR) nt 3243 A-->G and nt 3316 G-->A mutations in Chinese patients with type 2 diabetes.

Seven hundred and sixteen randomly selected, unrelated patients with type 2 diabetes were screened for mutations using a PCR-RFLP technique to assess the prevalence of the A-G mutation at position 3243 of the mitochondrial (mt) tRNAleu(UUR) gene in type 2 diabetes in the Chinese population. Three individuals with this mutation were identified, representing approximately 0.4% of the type 2 diabetes patients screened. Further screening of the first-degree relatives of these three patients identified another four affected carriers. In comparison with type 2 diabetic patients without the mutation, these seven carriers of the mt 3243 mutation had; (1) had an earlier onset of diabetes (38.0+/-10.1 vs. 53.4+/-10.0 year, P<0.001); (2) a lower body mass index (BMI) (19.5+/-2.0 vs. 24.9+/-10.9, P<0.0001); and (3) and lower post-challenge insulin levels (area under the curve of insulin levels during the OGTT, 2946+/-1647.2 vs. 7469+/-6647.7, P<0.01). In addition, the same 716 patients with type 2 diabetes, as well as 181 controls with normal glucose tolerance, were screened for a newly described mt 3316 G-A mutation. This mutation was found in 16 patients with type 2 diabetes (2.2%) and five controls (2.7%). Therefore, the frequency of the mutation was not significantly different in the patients and controls. Moreover, the clinical characteristics such as the age of the onset of diabetes, the BMI, and insulin levels were not significantly different between the diabetic patients with the mt 3316 G-A mutation and those without. This shows that the mt 3316 G-A mutation is a polymorphism unrelated to diabetes.

Asian People↗
PubMed2001

Cloning and characterization of porcine insulin gene.

The complete porcine preproinsulin cDNA and 1022 bp of its 5'-flanking region have been cloned by PCR-based technology and characterized. The porcine insulin gene has the same structure of three exons and two introns as that found in all insulin genes sequenced to date. Northern blot analysis of isolated adult porcine islets demonstrated an increase in steady-state insulin mRNA levels in response to high concentrations of glucose. Highly conserved cis-acting elements were found in the 5'-flanking region of the porcine insulin gene including multiple E and A elements as well as a cAMP responsive element (CRE). Tissue-specific activity of the proximal promoter was confirmed by transient transfection of the promoter/reporter gene constructs. This information now makes it possible for regulation and expression of the porcine insulin gene to be analyzed.

Amino Acid Sequence↗
PubMed2001

Membrane structure and fusion-triggering conformational change of the fusion domain from influenza hemagglutinin.

The N-terminal domain of the influenza hemagglutinin (HA) is the only portion of the molecule that inserts deeply into membranes of infected cells to mediate the viral and the host cell membrane fusion. This domain constitutes an autonomous folding unit in the membrane, causes hemolysis of red blood cells and catalyzes lipid exchange between juxtaposed membranes in a pH-dependent manner. Combining NMR structures determined at pHs 7.4 and 5 with EPR distance constraints, we have deduced the structures of the N-terminal domain of HA in the lipid bilayer. At both pHs, the domain is a kinked, predominantly helical amphipathic structure. At the fusogenic pH 5, however, the domain has a sharper bend, an additional 3(10)-helix and a twist, resulting in the repositioning of Glu 15 and Asp 19 relative to that at the nonfusogenic pH 7.4. Rotation of these charged residues out of the membrane plane creates a hydrophobic pocket that allows a deeper insertion of the fusion domain into the core of the lipid bilayer. Such an insertion mode could perturb lipid packing and facilitate lipid mixing between juxtaposed membranes.

Amino Acid Sequence↗
PubMed2001

Separation and preconcentration of MnVII/MnII speciation on crosslinked chitosan and determination by flame atomic absorption spectrometry.

A novel method for the separation and preconcentration of MnVII/MnII with crosslinked chitosan (CCTS) and determination by flame atomic absorption spectrometry (FAAS) has been developed. The adsorption rate of CCTS for MnVII was 98% at pH 3, while MnII was not adsorbed. MnVII was eluted from the CCTS with 10% (m/v) oxammonium hydrochloride and determined by FAAS. MnII was determined from the total manganese present after MnII in the water samples was transformed into MnVII. The detection limit (3 sigma, n = 10) for MnVII was 1.98 micrograms l-1 and the relative standard deviation less than 6.6% at the 10 micrograms l-1 level. The method was applied to environmental water samples with recoveries of between 95-103%.

Journal Article↗
PubMed2001

Plasmalogen deficiency in early Alzheimer's disease subjects and in animal models: molecular characterization using electrospray ionization mass spectrometry.

To explore the hypothesis that alterations in ethanolamine plasmalogen may be directly related to the severity of dementia in Alzheimer's disease (AD), we performed a systematic examination of plasmalogen content in cellular membranes of gray and white matter from different regions of human subjects with a spectrum of AD clinical dementia ratings (CDR) using electrospray ionization mass spectrometry (ESI/MS). The results demonstrate: (1) a dramatic decrease in plasmalogen content (up to 40 mol% of total plasmalogen) in white matter at a very early stage of AD (i.e. CDR 0.5); (2) a correlation of the deficiency in gray matter plasmalogen content with the AD CDR (i.e. approximately 10 mol% of deficiency at CDR 0.5 (very mild dementia) to approximately 30 mol% of deficiency at CDR 3 (severe dementia); (3) an absence of alterations of plasmalogen content and molecular species in cerebellar gray matter at any CDR despite dramatic alterations of plasmalogen content in cerebellar white matter. Alterations of ethanolamine plasmalogen content in two mouse models of AD, APP(V717F) and APPsw, were also examined by ESI/MS. A plasmalogen deficiency was present (up to 10 mol% of total plasmalogen at the age of 18 months) in cerebral cortices, but was absent in cerebella from both animal models. These results suggest plasmalogen deficiency may play an important role in the AD pathogenesis, particularly in the white matter, and suggest that altered plasmalogen content may contribute to neurodegeneration, synapse loss and synaptic dysfunction in AD.

Aged↗
PubMed2001

Gender influences herpes simplex virus type 1 infection in normal and gamma interferon-mutant mice.

Gender influences the incidence and severity of some bacterial and viral infections and autoimmune diseases in animal models and humans. To determine a gender-based difference, comparisons were made between male and female mice inoculated with herpes simplex virus type 1 (HSV-1) by the corneal route. Mortality was higher in the male mice of the three strains tested: 129/Sv//Ev wild type, gamma interferon (IFN-gamma) knockout (GKO), and IFN-gamma receptor knockout (RGKO). Similarly, in vivo HSV-1 reactivation occurred more commonly in male mice, but the male-female difference in reactivation was restricted to the two knockout strains and was not seen in the 129/Sv//Ev control. Comparison among male mice of the three strains showed a higher mortality of the RGKO mice and a higher reactivation rate of the GKO and RGKO mice than of the 129/Sv//Ev males. In contrast, female RGKO and GKO mice did not differ from female 129/Sv//Ev controls in either mortality or reactivation. HSV-1 periocular and eyelid disease was also more severe in male and dihydrotestosterone (DHT)-treated female mice than in control female mice. These results show a consistent gender difference in HSV-1 infection, with a worse outcome in male mice. In addition, the results comparing GKO and RGKO mice to controls show differences only in male mice, suggesting that some effects of IFN-gamma, a key immunoregulatory molecule, are gender specific.

Acute Disease↗
PubMed2001

Rat colon ornithine and arginine metabolism: coordinated effects after proliferative stimuli.

Ornithine decarboxylase (ODC) catalyzes the first step in the polyamine biosynthetic pathway, a highly regulated pathway in which activity increases during rapid growth. Other enzymes also metabolize ornithine, and in hepatomas, rate of growth correlates with decreased activity of these other enzymes, which thus channels more ornithine to polyamine biosynthesis. Ornithine is produced from arginase cleavage of arginine, which also serves as the precursor for nitric oxide production. To study whether short-term coordination of ornithine and arginine metabolism exists in rat colon, ODC, ornithine aminotransferase (OAT), arginase, ornithine, arginine, and polyamine levels were measured after two stimuli (refeeding and/or deoxycholate exposure) known to synergistically induce ODC activity. Increased ODC activity was accompanied by increased putrescine levels, whereas OAT and arginase activity were reduced by either treatment, accompanied by an increase in both arginine and ornithine levels. These results indicate a rapid reciprocal change in ODC, OAT, and arginase activity in response to refeeding or deoxycholate. The accompanying increases in ornithine and arginine concentration are likely to contribute to increased flux through the polyamine and nitric oxide biosynthetic pathways in vivo.

Animals↗
PubMed2001

Ion-channel sensing of ferricyanide anion based on a supported bilayer lipid membrane.

Ferricyanide anion has usually been used as a marker of ion-channel sensors. In this work we first found that ferricyanide, itself, can act as a stimulus to regulate the permeability of sBLM prepared from didodecyldimethylammonium bromide (a kind of synthetic lipid) on a GC electrode. We used cyclic voltammetry and a.c. impedance to investigate this phenomenon. The interaction between sBLM and ferricyanide concerns time. Furthermore, we developed a sensor for ferricyanide anion. The ion-channel sensor is highly sensitive. It can detect ferricyanide concentration as low as 5 microM.

Anions↗
PubMed2001

Sequence specific recognition of ligand-DNA complexes studied by NMR.

The last few years have represented an accelerated accumulation in detailed information about ligand-DNA interactions. A collected view of literature information is essential for advancing our understanding of the principles of ligand-DNA recognition, utilizing this valuable information for construction of a modeling database, and eventually the rational design of DNA-binding ligands possessing desired properties. This review is concentrated on structure-based information on ligand-oligodeoxyribonucleotide (DON) complexes published since 1995, especially focusing on the results obtained from NMR structure elucidation. The discussions emphasize the sequence specific recognition of novel binding motifs or binding modules of ligand molecules rather than specific atomic details. A comprehensive list of DNA binding ligands are discussed in the text and are also summarized in a table. The DNA sequences that are recognized by specific ligand molecules as studied by NMR are annotated in a figure to provide a clear view of target selection. This review also briefly describes NMR methods for characterization and structure elucidation of ligand-DNA complexes.

Antineoplastic Agents↗
PubMed2001

Tissue inhibitor of metalloproteinase-1 prevents cytokine-mediated dysfunction and cytotoxicity in pancreatic islets and beta-cells.

In addition to inhibiting matrix metalloproteinase-2 and matrix metalloproteinase-9 activity, recent studies suggest that tissue inhibitor of metalloproteinase (TIMP)-1 may inhibit apoptosis in various cell lines. To address this question in pancreatic islets and beta-cells, we treated rat pancreatic islets and INS-1 cells with a high-dose combination of the cytokines interleukin (IL)-1beta, tumor necrosis factor-alpha, and interferon-gamma with or without the addition of TIMP-1 and TIMP-2 protein. Using flow cytometry, we quantitated DNA fragmentation to assess cellular apoptosis and confirmed these observations with DNA laddering experiments. Next, we transfected the mouse TIMP-1 gene into INS-1 cells and performed Western immunoblotting to demonstrate expression of TIMP-1 protein. We treated TIMP-1-expressing INS-1 cells with high-dose cytokines and again used flow cytometry to assess DNA fragmentation. We also evaluated the effect of TIMP-1 on IL-1beta-induced inhibition of glucose-stimulated insulin secretion (GSIS) in freshly isolated rat pancreatic islets. Finally, we evaluated the effect of TIMP-1 on inducible nitric oxide synthase (iNOS) gene expression and nuclear factor (NF)-kappaB activity in INS-1 cells stimulated with high-dose cytokines. TIMP-1 but not TIMP-2 prevented cytokine-induced apoptosis and cytokine-mediated inhibition of GSIS in rat islets and beta-cells. TIMP-1 mediated these effects by inhibiting cytokine activation of NF-kappaB, but it did not affect nitric oxide production or iNOS gene expression. Therefore, TIMP-1 may be an ideal gene to prevent cytokine-mediated beta-cell destruction and dysfunction in models of type 1 diabetes and islet transplantation rejection.

Animals↗
PubMed2001

[Expression of rasp21, C-myc, C-erbB-2, and AFP in 2-FAA induced experimental hepatocarcinogenesis].

OBJECTIVE: To investigate the distribution of oncogenes and their relationships in 2-FAA induced experimental hepatocarcinogenesis. METHODS: Rasp21, C-myc, C-erbB-2, and AFP were detected and analyzed by the SP method of immunohistochemistry. RESULTS: Some cells expressed rasp21, C-myc, and AFP in peripheral liver lobules and alternated hepatocyte foci in the early stage of the experiment. And with the formation and progression of hyperplastic hepatocytic nodules, expressed cells increased and often accompanied each other. Expression of C-erbB-2 appeared in the middle stage of the hepatocarcinogenesis. CONCLUSIONS: Expression of rasp21, C-myc, and AFP in the experimental hepatocarcinogenesis is an early molecule change, which may relate to the initiation of hepatocarcinogenesis and be considered to be one of the molecular bases for the morphogenesis of hepatocarcinogenesis. During the development of lesion, C-erbB-2 may have promoting effects. It is also clear that malignant transformation of hepatocyte needs the cooperation of multiple oncogenes.

2-Acetylaminofluorene↗
PubMed2001

[Association between angiotensin system gene polymorphism and essential hypertension].

OBJECTIVE: To investigate whether angiotensinogen(AGT) M235T, angiotensin II type I receptor(AT(1)R) gene A1166C and angiotensin converting enzyme(ACE) gene I/D polymorphism are implicated in human essential hypertension(HT) in Chinese. METHODS: Polymerase chain reaction(PCR) and PCR combined with restriction enzyme digestion were used to detect AGT gene M235T, AT(1)R gene A1166C variations and ACE gene I/D polymorphism in 161 hypertensive patients and 134 normotensive controls. RESULTS: No statistically significant differences were found in frequencies of the ACE D allele, AGT gene 235T and AT(1)R A1166C between hypertensive patients and normotensive controls, but in hypertensive patients aged <60 years the frequencies of the ACE D allele and AGT gene 235T were significantly higher than those of the normotensive controls (P<0.05). The analysis of combined genotypes of AGT gene and ACE gene showed that the combined genotypes of DD-TT and ID-TT were significantly higher in hypertensive patients than in normotensive controls. Significant relationships between the ACE genotype and serum ACE activity were found in both groups(P<0.05). CONCLUSION: The ACE D allele and AGT 235T polymorphism may be involved in the early occurrence of HT. The combined genotypes of DD-TT and ID-TT may be a dangerous genetic factor for HT in Chinese.

Adult↗
PubMed2001

[Study on weekly low doses of mifepristone for contraception].

OBJECTIVE: To study whether weekly low dose of mifepristone (5 mg or 10 mg) is sufficient to prevent pregnancy. METHODS: Thirty-nine women were randomly allocated to take mifepristone 5 mg (group A) or 10 mg (group B) doses once weekly starting on cycle day 2-3. The serum levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were determined by enzymeimmunoassay (EIA), and estradiol (E2) and progesterone (P) levels by radioimmunassay (RIA). Serum mifepristone concentrations were measured by high performance liquid chromatography (HPLC). Morphometric analyses and progesterone receptor (PR), Dolichus biflorus agglutinin (DBA-lectin) and integrin alpha v beta 3 of endometrium were also measured. RESULTS: There were 4 pregnancies out of 64 cycles in group A, and 3 out of 68 cycles in group B. Normal LH and FSH peak could be detected in the first treatment cycles, LH peak appeared on 15-17 d. The concentrations of P were (51.93 +/- 7.91) nmol/lL and (69.00 +/- 21.29) nmol/L in group A and B respectively. The average level of E2 was (407.81 +/- 89.27) pmol/L in group A, and (557.85 +/- 204.69) pmol/L in group B. Serum mifepristone level could be detected within 36 hours. The PR concentration in endometrium decreased significantly, but not of DBA-lectin, integrin alpha v beta 3. CONCLUSIONS: Administration of mifepristone 5 mg or 10 mg once weekly does not inhibit ovulation completely. The follicular phase prolonged slightly, and E2 levels were low following treatment. The endometrium showed delayed development. The clinical contraceptive effectiveness needs to be improved.

Adult↗
PubMed2001

Prevalence and clinical characteristics of mitochondrial tRNA leu(UUR) mt 3243 A-->G and ND-1 gene mt 3316 G-->A mutations in Chinese patients with type 2 diabetes.

OBJECTIVE: To assess the prevalence of mitochondrial tRNA leu(UUR) gene mt 3243 A-->G mutation and ND-1 gene mt 3316 G-->A mutation in Chinese type 2 diabetes. METHODS: 716 randomly selected, unrelated patients with type 2 diabetes were screened for the mutation with a PCR-RFLP technique. RESULTS: Three individuals with mitochondrial tRNA leu(UUR) gene mt 3243 A-->G mutation were identified, representing approximately 0.4% of the type 2 patients screened. Further screening of first-degree relatives of these 3 patients identified another 4 affected carriers. In comparison with type 2 diabetic patients without the mutation, these 7 carriers of the mt3243 mutation had: 1) an earlier diagnosis age of diabetes (38.0 +/- 10.1 year vs 53.4 +/- 10.0 year, P < 0.001); 2) lower Body Mass Index (BMI) (19.5 +/- 2.0 kg/m2 vs 24.9 +/- 10.9 kg/m2, P < 0.0001); and 3) lower post-challenge insulin levels (Area under the curve of insulin levels during the Oral Glucose Tolerance Test (OGTT), 2946 +/- 1647.2 microIU.ml-1 vs 7469 +/- 6647.7 microIU.ml-1, P < 0.01). ND-1 gene mt 3316 G-->A mutation was found in 16 patients with type 2 diabetes (2.2%) and 5 out 181 controls (2.7%) with normal glucose tolerance. Therefore, the frequency of the mutation was not different in patients and controls. Moreover, clinical characteristics such as age of onset of diabetes, BMI, and insulin levels were not different between diabetic patients with the mt 3316 mutation and those without it. CONCLUSIONS: In this large cohort of Chinese Type 2 diabetes, the prevalence of mitochondrial tRNA leu(UUR) gene mt 3243 A-->G mutation was 0.4%, and the ND-1 gene mt 3316 G-->A mutation is a polymorphism unrelated to diabetes.

Aged↗