Biomedical subjects
Publications and source records attributed to T Li.
Dendrobium drug, a rare medicinal herb, reproduces differcut for growth environment to lead rare resources. By studying of cultivation for many many years in Fuliu mountain area, authors had found out the cultivated method simulating the habitat of wild Dendrobium flexicaule. The results could supply a basis for its development and utilization.
The film-forming properties of 5,10,15,20-tetra-(4-hexadecylpyridiniumyl)porphyrin bromide (TC16PyP) on the air/water interface were studied. LB films of the amphiphilic porphyrin were prepared on the glass, quartz and SnO2 OTE substrates. The morphology and structure of TC16PyP LB films were characterized by scanning tunnelling microscope, UV-Vis absorption spectra, fluorescence spectra and low-angle X-ray diffraction. The experimental results indicated that the amphiphilic porphyrin TC16PyP has good film-forming properties on the air/water interface, its LB films are stable, in TC16PyP monolayer or LB films the long alkyl chains are not straight and the porphyrin macroring is lying nearly parallel to the substrate surface.
A new one-pot synthesis was designed to prepare benzoyl-AMP under anhydrous conditions in N,N-dimethylformamide. Reaction of benzoic acid with N,N'-carbonyldiimidazole and subsequently with 5'-adenosyl monophosphate gave the mixed anhydride in 76% isolated yield. The structure of benzoyl-AMP was confirmed by mass spectroscopy and 1H-, 31P-, and 13C-NMR. The purity of the preparation was greater than 98% as indicated by 31P- and 13C-NMR. Purified aryl-aldehyde oxidoreductase was incubated in NMR tubes together with either carboxy-13C-benzoyl-AMP or carboxy-13C-benzoic acid to demonstrate that benzoyl-AMP is an active intermediate during the enzymatic reduction of benzoic acid to benzaldehyde.
The crystal structure of the heterodimer formed by the DNA binding domains of the yeast mating type transcription factors, MATa1 and MATalpha2, bound to a 21 bp DNA fragment has been determined at 2.5 A resolution. The DNA fragment in the present study differs at four central base pairs from the DNA sequence used in the previously studied ternary complex. These base pair changes give rise to a (dA5).(dT5) tract without changing the overall base composition of the DNA. The resulting A-tract occurs near the center of the overall 60 degrees bend in the DNA. Comparison of the two structures shows that the structural details of the DNA bend are maintained despite the DNA sequence changes. Analysis of the A5-tract DNA subfragment shows that it contains a bend toward the minor groove centered at one end of the A-tract. The observed bend is larger than that observed in the crystal structures of A-tracts embedded in uncomplexed DNA, which are straight and have been presumed to be quite rigid. Variation of the central DNA base sequence reverses the two AT base pairs contacted in the minor groove by Arg7 of the alpha2 N-terminal arm without significantly altering the DNA binding affinity of the a1/alpha2 heterodimer. The Arg7 side chain accommodates the sequence change by forming alternate H bond interactions, in agreement with the proposal that minor groove base pair recognition is insensitive to base pair reversal. Furthermore, the minor groove spine of hydration, which stabilizes the narrowed minor groove caused by DNA bending, is conserved in both structures. We also find that many of the water-mediated hydrogen bonds between the a1 and alpha2 homeodomains and the DNA are highly conserved, indicating an important role for water in stabilization of the a1/alpha2-DNA complex.
BACKGROUND: Family studies of schizophrenia and bipolar affective disorder provide evidence for genetic anticipation, which (in common with a number of mendelian disorders), may be caused by triplet repeat expansion. This hypothesis is strengthened by evidence from repeat expansion detection (RED) analysis revealing association between the psychoses and long CAG/CTG trinucleotide repeats. METHODS: We performed RED on Han Chinese subjects with schizophrenia (82), bipolar affective disorder (43), and normal controls (61), using a CTG10 oligonucleotide. RESULTS: Comparison between cases and controls revealed no significant association between long repeats and affected status. We also found no detectable association with age at onset and repeat length in either bipolar affective disorder or schizophrenia. Overall, the size distribution of CAG/CTG repeats in Chinese subjects was not significantly different from those reported previously for Caucasian subjects. CONCLUSIONS: These findings indicate that CAG/CTG repeat expansion is not likely to be a major etiological factor for psychosis in Chinese populations.
Alkannin and shikonin are naturally occurring naphthoquinones. We have tested several derivatives of the title compounds and we have found that naphthoquinones bearing at least one phenolic hydroxyl group are potent inhibitors of topoisomerase I. The ability of the tested compounds to complex Zn++ parallels with a few exceptions their topoisomerase I inhibition properties while their intercalation and redox properties do not.
hKCa3 is a neuronal small conductance calcium-activated potassium channel which contains a polyglutamine tract, encoded by a polymorphic CAG repeat in the gene. Since an association between longer alleles of the CAG repeat and schizophrenia has been reported, we performed haplotype-based haplotype relative risk (HHRR) and transmission disequilibrium (TDT) in 97 family trios with schizophrenia from SW China. We found no evidence for an excess of longer CAG repeats in the patients, and the ETDT test was not significant for either allele-wise (P = 0.31) or genotype-wise analysis (P = 0.18). However, there was a deficit of transmission of the (CAG)20 repeat allele to affected offspring when this allele was considered individually by TDT (P = 0.012; not corrected for multiple testing). These data do not support a role for larger alleles at the hKCa3 locus in psychosis in Chinese subjects.
A therapeutic effect of vitamin A supplementation on the course of photoreceptor degeneration, previously reported for patients with retinitis pigmentosa, was tested in two transgenic mouse models of this disease, each carrying a dominant rhodopsin mutation. The threonine-17 --> methionine (T17M) mutation is a class II rhodopsin mutation, characterized by a thermal instability/folding defect and minimal regeneration with the chromophore. The proline-347 --> serine (P347S) mutation belongs to class I, comprised of a smaller number of mutations that exhibit no recognized biochemical abnormality in vitro. In the present study, each of the two mouse models was fed a diet containing 2.5 mg of vitamin A palmitate (control) or 102.5 mg of vitamin A palmitate (high vitamin A) per kilogram of diet. Dark-adapted, full-field electroretinograms showed that the high vitamin A diet significantly reduced the rate of decline of a-wave and b-wave amplitudes in the T17M mice but had no significant effect on the decline of electroretinogram amplitude in the P347S mice. Correspondingly, histologic evaluation revealed that the treatment was associated with significantly longer photoreceptor inner and outer segments and a thicker outer nuclear layer in the T17M mice but had no effect on photoreceptor morphology in the P347S mice. In a separate series of experiments, the instability defect of the T17M mutant opsin expressed in vitro was partially alleviated by inclusion of 11-cis-retinal in the culture media. These results show that vitamin A supplementation slows the rate of photoreceptor degeneration caused by a class II rhodopsin mutation. Vitamin A supplementation may confer therapeutic benefit by stabilizing mutant opsins through increased availability of the chromophore.
OBJECTIVES: To identify the reasons for non-compliance with fecal occultblood test in the screening programme for colorectal cancer. DESIGN AND SETTING: The people who had never participated in the screening programme for colorectal cancer served as the subjects of this study. A structured questionnaire which included the reasons for rejection was sent to each of non-compliers. They were requested to choose two major reasons which were described in a best way that why they did not participate in the programme. The frequency of the stated reasons were analysed from the viewpoint of both sex and age effects. MAIN RESULTS: A total of 439 people was identified as non-compliers, and 356 (81.1%) people completed the questionnaire. No significant difference was noted in response to the questionnaire between male and female as well as aged 40-59 and those 60-79. The most commonest reason was felt well (47.8%) in male, fear or shyness of further examination (40.2%) in female, and also felt well (48.5%) in aged 40-59, fear or shyness of further examination (40.1%) in aged 60-79. Significant differences were observed in the frequencies of felt well (p<0.01), fear or shyness of further examination (p<0. 01), busy for work (p<0.01) and fear of cancer (p<0.01) between male and female, and also felt well (p<0.01), fear or shyness of further examination (p<0.01), busy for work (p<0.01) and coexistent disease (p<0.01) between aged 40-59 and those 60-79. CONCLUSIONS: These results suggest that public education about the concept of asymptomatic illness, the benefits of early detection, the safety and painless colonoscopy, and the effective treatment should be emphasised to increase compliance with screening for fecal occult blood.
To elucidate the mechanisms by which glucocorticoids promote Th2-type responses, we investigated the influence of dexamethasone (DEX) on both cytokine production and viability of NK1.1+ T cells. The in vivo administration of DEX enhanced the IL-4 production of spleen cells and liver mononuclear cells in wild-type mice, but not in beta2m-deficient mice. DEX reduced the cellularity of conventional T cells, but not that of NK1.1+ T cells, in both spleen and liver, suggesting an increased proportion of NK1.1+ T cells. Moreover, the proportion of IL-4-producing NK.1 + T cells increased in the DEX-injected mice. These results suggest that DEX induced IL-4 production through the preferential survival of IL-4-producing NKI.1+ T cells. In investigating the reason for the preferential survival of NK1.1+ T cells, we found that NK1.1+ T cells were resistant to DEX-induced apoptosis and expressed a higher level of intracellular Bcl-2 compared with conventional NKI.1- T cells. In addition, splenic and hepatic NK1.1+ T cells were resistant to radiation-induced apoptosis. Collectively, our findings revealed an important role for NK1.1+ T cells in the regulation of Th1/Th2 balance by glucocorticoids and their possible functions under various apoptotic stimuli.
The dopamine system has long been suspected of aetiological involvement in schizophrenia because of a number of lines of evidence pointing to excess dopaminergic activity in the illness. Recently, negative allelic association was reported between a single base deletion in the promoter region of the DRD2 gene, -141 delta C, and schizophrenia, with an odds ratio of 0.60. This was of particular interest since the deletion, which occurs in about 22% of the Japanese population, is functional in that it results in reduced (20-40% of wild-type) basal levels of receptor expression. We have examined this polymorphism in 229 family trios from SW China, consisting of both parents and a single offspring affected by schizophrenia, and 151 Caucasian cases with schizophrenia and 145 Caucasian normal controls from the UK. Using the haplotype-based haplotype relative risk method (HHRR), the frequency of the -141 delta C allele was 6.9% in the affected Chinese subjects compared to an estimated frequency of 9.0% in this population (chi 2 = 1.21, 1 df, ns), with an odds ratio of 0.76 (95% CI 0.46-1.25). Using the transmission disequilibrium test, we likewise found no evidence for linkage or linkage disequilibrium with this polymorphism (chi 2 = 0.94, 1 df, ns). In the Caucasian cases, the frequency of the -141 delta C was 13% compared to 10% in controls (chi 2 = 1.57, p = 0.21) with an odds ratio of 1.39 (95% CI 0.81-2.40). We thus conclude that the DRD2 -141 delta C polymorphism is less frequent in Chinese and Caucasian populations (9%) than in Japan (22%) and is not a significant risk factor for schizophrenia in our populations. The -141 delta C allele remains a strong candidate for a variety of other traits and diseases, including reward-related behaviours such as drug abuse, which have been associated with the dopamine system.
OBJECTIVES: The present study was carried out to assess compliance rates with annual colorectal cancer screening for fecal occult blood, and to identify the subjects with higher priority in health education to increase screen compliance. DESIGN AND SETTING: A screening program for colorectal cancer was conducted between 1982 and 1995 in a Japanese villlage. Screen compliance rates in this program were summarised related to sex distribution as well as 10-year age cohorts. MAIN RESULTS: Screen compliance declined slowly during 14 years time period, and averaged 55.4%. Mean screen compliance was significantly higher in women (56.8%) than in men (53. 8%), and also in aged 50-79 (63.5%) than in aged 50 or less (43.8%), and those 80 and older(12.3%). Subjects who experienced a negative result on colonoscopic examination had significantly lower compliance with screening. CONCLUSIONS: These findings indicate that the youngest as well as oldest subjects, and the subjects with negative results of fecal occult blood test should be given higher priority in health education to improve screen compliance.
Novel antitumor 5,10-dihydro-5,10-dioxo-1H- benzo[g]isochromene-3-carboxamides were discovered.
Transcription of the stationary-phase sigma factor RpoS of Salmonella typhi increased in the macrophage. A single rpoS mutant of S. typhi was constructed to analyze the role of RpoS in intracellular multiplication of the bacterium and host cell killing. This mutant was sensitive to starvation, low pH and hydrogen peroxide; however, it could still multiply inside resting macrophages and was less cytotoxic than the wild-type strain. Therefore, S. typhi might produce RpoS-dependent factors which could contribute to host cell death.
In order to study the expression of Fos protein in catecholaminergic neurons in the medullary visceral zone (MVZ), which project to the habenular nucleus (HB), a triple-labeling method combining wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) retrograde tracing with anti-Fos and anti-tyrosine hydroxylase (TH) immunohistochemical staining was used in the rat. WGA-HRP was stereotaxically injected into unilateral HB. Forty-eight hours later, 50 microl of 8% formalin was injected into the foot pad of the right front paw. Two hours after formalin injection, animals were anesthetized and perfused transaortically. Coronal sections (40 micron) were cut from the cervical segment of spinal cord, the medulla oblongata and WGA-HRP injected area with a cryostat. First, sections of the injected area and the medulla oblongata were histochemically processed to demonstrate the presence of retrogradely transported WGA-HRP using the chromogen tetramethylbenzidine (TMB). Then sections of the spinal cord and the medulla oblongata were immunostained with anti-Fos and anti-TH antibodies using the ABC method. Under the light microscope, seven types of variously labeled neurons could be identified in MVZ, namely Fos and TH-immunoreactive (Fos- or TH-IL) neurons, WGA-HRP labeled ones, Fos/HRP, Fos/TH and HRP/TH double-labeled and Fos/HRP/TH triple-labeled cells. The results suggest that some catecholaminergic neurons in MVZ could send projections to HB and this pathway may be involved to relay nociceptive information from spinal cord to brainstem and on to the forebrain.
We investigated the effect of the systemic administration of interleukin (IL)-12 on the anti-tumor potential of tumor-draining lymph nodes (LNs). Tumor-draining LN cells on day 10 after s.c. inoculation of B16 melanoma showed a significant anti-tumor effect against established pulmonary metastases after in vitro expansion, whereas those on either day 20 or 30 exhibited an impaired anti-tumor potential. However, i.p. injections of IL-12 (0.5 microg) on days 18, 20 and 22 significantly increased the total number of tumor-draining LN cells on day 24 and, furthermore, restored their anti-tumor potential after in vitro expansion. In addition, i.p. injection of IL-12 (0.1 microg) on days 20, 22, 24, 26 and 28 significantly suppressed the growth of s.c.-inoculated B16 melanoma and finally cured the tumors in 6 of 12 mice (50%), whereas dissection of the tumor-draining LNs on day 18, prior to the IL-12 treatment, decreased both the IL-12-induced anti-tumor effect and the percentage of cured mice (8.3%). Cured mice acquired a specific protective immunity. Collectively, our results indicate that the systemic administration of IL-12 can restore the immunotherapeutic potential of tumor-draining LNs, which was impaired at the late tumor-bearing state, and that the IL-12-induced systemic anti-tumor activity is preceded by the restoration of an anti-tumor response in tumor-draining LNs.
To characterize chemical carcinogens in acidic-nitrosated fish sauce sample, N-nitrosamides in the sample were separated by two kinds of reversed-phase HPLC columns, and with detection by photolysis-pyrolysis-thermal energy analyzer. A strong chromatographic peak at t(R) 12 or 4.5 min, same as that for N-(nitrosomethyl)urea (NMU), was obtained on PRP-1 or C(18) HPLC column from fish sauce sample with 10 mM trifluoroacetic acid as the basic mobile; acetonitrile, as organic modifier after the sample was nitrosated by 5 mmol/L of sodium nitrite (final concentration) at 37 degrees C and pH 2.0 for 1 h. No response above t(R) could be observed from the nitrosated sample in the detection system without photolysis. Such a peak could not be obtained from the unnitrosated fish sauce either. These results indicated that the component was NMU. Furthermore, this component, NMU, could also be detected in the nitrosated human gastric juice sample spiked with fish sauce. The formation of NMU in the sample was pH- and nitrite-dependent. This paper provides direct evidence that NMU formation could occur in fish sauce from the high-risk area for stomach cancer and in the fish sauce spiked human gastric juice during nitrosation under simulated gastric conditions.
CD30 engagement in human lymphoid cells induces pleiotropic cellular responses that affect cellular viability and proliferation, cytokine production, and nuclear factor kappaB (NF-kappaB) nuclear translocation. Studies examining the molecular basis for this pleiotropism thus far have relied on the use of antibodies and cells transfected with CD30L to trigger CD30, two methods of receptor induction that present important limitations: antibodies are not physiological receptor-triggering molecules and CD30L transfectants induce high background intracellular signaling in the cells under study. We have generated and expressed a functional soluble human CD30L molecule (sCD30L/CD8alpha) comprised of the extracellular domain of human CD30L fused to the extracellular domain of the human CD8alpha chain. Immunoprecipitation and Western blot analysis of sCD30L/CD8alpha revealed the existence of at least two forms of sCD30L/CD8alpha, which exhibited molecular sizes consistent with the existence of monomeric and trimeric forms of the molecule. Binding analyses performed using a soluble CD30 fusion protein (sCD30/gamma1) confirmed the ability of sCD30L/CD8alpha to bind to CD30. Functionally, immobilized sCD30L/CD8alpha-induced cell death in the CD30-expressing lines Karpas-299 and HDLM-2 and reduced proliferative levels in Karpas-299; these effects were inhibitable by the addition of sCD30/gamma1. These studies demonstrate the utility of sCD30L/CD8alpha in characterizing the normal function of CD30L and CD30 and indicate the natural ability of soluble forms of CD30L to trimerize.