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Biomedical subjects

H Shi

Publications and source records attributed to H Shi.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Telomerase activity in cervical cancer and its precursor lesion].

OBJECTIVE: To study telomerase activity in cervical cancer and it's precursor lesion. METHODS: Thirty-six cervical cancer and 16 cervical intraepithelial neoplasia (CIN) specimens were measured for telomerase activity using TRAP-ELISA, and 11 normal cervix, 6 chronic cervicitis and 8 adjacent normal tissue specimens as controls. RESULTS: Mean telomerase activity in CIN, cervical cancer, and controls were 0.398 +/- 0.293, 1.580 +/- 0.819, 0.050 +/- 0.012. There was statistically significant difference among three groups (P < 0.01). Additionally, between patients with lymph node metastases (N+) and patients with tumor-free lymph nodes metastases (N-) a statistically distinct difference in telomerase activity was detected (P < 0.05). Telomerase activity was increasing with the advancing of histologic differentiated grade in invasive cervical cancer. However, no significant relationship was found between telomerase activity and tumor size, clinical stage, histology. CONCLUSIONS: Our data suggest that the reactivation of telomerase is an early event and may play an important role during cervical carcinogenesis and progression. It may be used as a tumor biomarker, helpful for the diagnosis of cervical cancer and CIN.

Adult↗
PubMed2001

[Mobilization of autologous peripheral blood stem cells by combined chemotherapy and rhG-CSF].

OBJECTIVE: To study the effect of cyclophosphamide (CTX) combination chemotherapy and recombinant human granulocyte colony-stimulating factor (rhG-CSF) on autologous peripheral blood stem cells (APBSC) mobilization. METHODS: CTX(2.5 +/- 1.0) g/m2 on day 1, VP-16,600-800 mg and/or Ara-C 1.0-2.0 g/m2 on day 2 were injected i.v. rhG-CSF 300 micrograms/d was injected s.c. when the white blood cell (WBC) count reached nadir until one day before APBSC harvest. When the WBC count was over 3.0 x 10(9)/L, peripheral blood mononuclear cell (MNC) collection was performed once per day until the number of MNC collected was > 4 x 10(8)/kg. CFU-GM colony formation and CD34+ cell enumeration were performed. RESULTS: Twenty cases were studied. The lowest level of WBC was (1.2 +/- 0.8) x 10(9)/L on day 8.5 +/- 1.5 following chemotherapy. rhG-CSF was given from day 9.0 +/- 2.0 and continued for 6.0 +/- 1.0 days. APBSC harvest began on day 12.0 +/- 2.0 and continued for 4.0 +/- 1.0 days. A total of (6.14 +/- 2.34) x 10(8)/kg MNC and (23.25 +/- 30.56) x 10(6)/kg CD34+ cells was procured. Peak level of CD34+ cells was observed 14.6 +/- 1.8 days after chemotherapy and 4.9 +/- 1.6 days after rhG-CSF administration. CFU-GM was (21.68 +/- 15.39) x 10(4)/kg when rhG-CSF was given for 4.9 +/- 1.6 days. No severe toxic reaction was observed. Hematopoietic reconstitution was very well in all patients received APBSC transplantation. CONCLUSION: CTX combination chemotherapy followed by rhG-CSF was safe and feasible for APBSC mobilization.

Adolescent↗
PubMed2001

[A study on antigen presentation of eosinophils in vivo and in vitro].

OBJECTIVE: To elucidate the process and characteristics of antigen presentation of eosinophils in vitro and in vivo. METHODS: BALB/c mice were sensitized and challenged by ovalbumin to recruit the aggregated eosinophil in the airways. The isolated airway eosinophils were co-cultured with sensitized T lymphocytes. Meanwhile, purified eosinophils were instilled into the trachea of sensitized mice, and then T cells from the draining lymph nodes were collected. The proliferation responses of T cells both in vitro and in vivo were observed. RESULTS: In the absence of eosinophils in in vitro experiments, T cells did not proliferate even when incubated with exogenous antigen. The addition of ovalbumin sensitized eosinophils (in vivo) yielded significant eosinophil dose-dependent increases in T-cell proliferation. In sensitized mice that received airway instillation of antigen-exposed eosinophils, T-cell proliferation in the paratracheal lymph nodes developed within 1 day, reaching peak at day 3, and declined over 1 week. The in vivo T-cell proliferative responses increased with increasing numbers of eosinophils instilled into the tracheas. In both in vitro and in vivo experiments, antigen-exposed could only present antigen to T cells sensitized with the same antigen. CONCLUSIONS: Eosinophils can uptake and process antigen both in vitro and in vivo, and then present processed antigen to sensitized T cells and thus induce T-cell proliferation. Moreover, eosinophil-induced T-cell proliferation is antigen specific.

Animals↗
PubMed2001

[Difference of T helper cell subsets and B7 co-stimulatory molecule expressions by alveolar macrophages in bronchoalveolar lavage fluid between patients with allergic asthma and chronic obstructive pulmonary disease].

OBJECTIVE: To elucidate the differences of T helper cell subsets and expressions of B7 co-stimulatory molecules by alveolar macrophages (AM) between patients with allergic asthma and chronic obstructive pulmonary disease (COPD). METHODS: Bronchoalveolar lavage fluid (BALF) cells were obtained from 16 normal control volunteers, 16 patients with allergic asthma and 16 patients with COPD. IFN-gamma and IL-4 levels in the supernatant of BLAF lymphocytes cultured with PHA were determined using sandwich ELISA and the CD80 (B7-1) and CD86 (B7-2) expressed by AM stimulated with LPS were determined using avdin-biotin complex technique. RESULTS: In COPD group, IFN-gamma level was significantly higher than those of the control group and asthma group (P < 0.01). IFN-gamma in asthma group was lower than that of the control group (P < 0.01). IL-4 level and the ratio of AM expressing CD86 in asthma group were higher than those of the control group and COPD group (P < 0.01). The IL-4 level and ratio of AM expressing CD86 showed no significantly difference between COPD and control group (P > 0.05). The IL-4 levels in 3 groups were significantly positively correlated with the ratio of AM expressing CD86 (r = 0.61, P < 0.05). No difference of the ratio of AM expressing CD80 was found among three groups (P < 0.05). CONCLUSION: Asthma is characterized by a predominance of Th2-type response in BALF T cells, and COPD of Th1-type response in BALF T cells. The increased expression of co-stimulation of CD86 in AM is probably involved in Th2-type response in the airway inflammation in allergic asthmatics.

Adult↗
PubMed2001

[Effects of beta-carotene and vitamin C on the expression of c-myc in human leukemic cell].

In order to study the effects of beta-carotene and vitamin C(VC) on the expression of c-myc oncogene in human leukemic cell, myelogenous leukemic cell line HL-60 was cultured in vitro with standard methods. Trypan blue exclusion test and Northern blotting hybridization were used to detect the cell proliferation and the expression of c-myc gene. The results showed that the proliferation of HL-60 cell was inhibited after exposed to VC(5, 10, 100 mumol/L) and the occurrence of proliferation was earlier at lower concentration of VC(5 mumol/L). beta-carotene at 10-100 mumol/L could inhibit the proliferation of HL-60 cell in a dose dependent manner. VC(5 mumol/L) had no influence on the expression of c-myc gene(P > 0.05), but beta-carotene could up-regulate the expression of c-myc(P < 0.05). Our observations suggested that the inhibitory effect of beta-carotene on the proliferation of leukemic cells was caused by inducing apoptosis of HL-60 through up-regulating the expression of c-myc gene; however, the inhibitory effect of vitamin C on cell proliferation was not related to the expression of c-myc gene.

Ascorbic Acid↗
PubMed2001

[The clinical significance of detection of urinary ceruloplasmin in type 2 diabetes].

OBJECTIVE: To evaluate the clinical significance of detection of urinary ceruloplasmin (Cp) in type 2 diabetes. METHODS: To measure albumin/creatinine(Alb/Cr) and Cp/Cr in morning urinary specimens, from 134 normal controls and 3 960 diabetes, with RIA and ELISA separately. RESULTS: (1) The range of urinary Cp/Cr for normal controls was 0.01 - 1.12 ng/mmol, median 0.36 ng/mmol. Cp/Cr > 0.924 ng/mmol was considered as abnormal, and there was no significant difference between males and females, as well as among subjects of different age. (2) The sensitivity and specificity of Cp/Cr were 90% and 66% respectively with Alb/Cr > 2.5 mg/mmol as a golden standard for diabetic nephropathy, and Kappa value 0.48. Urinary Cp/Cr correlated well with Alb/Cr. (3)After sub-maximal exercise, Cp/Cr elevated markedly with no significant change of Alb/Cr. CONCLUSION: Urinary Cp/Cr could be considered as a marker of diabetic nephropathy and might be more sensitive than Alb/Cr.

Adult↗
PubMed2000

Effects of dietary calcium on adipocyte lipid metabolism and body weight regulation in energy-restricted aP2-agouti transgenic mice.

We have demonstrated previously a regulatory role for intracellular Ca2+ ([Ca2+]i) in adipocyte lipogenesis and lipolysis and have recently reported that 1,25-(OH)2-D increases adipocyte [Ca2+]i, which causes increased lipogenesis and decreased lipolysis. We have now tested the hypothesis that suppressing 1,25-(OH)2-D by increasing dietary calcium will suppress adipocyte [Ca2+]i, thereby facilitating weight loss by stimulating lipolysis and inhibiting lipogenesis in calorically (Kcal)-restricted (70% of ad lib) aP2-agouti transgenic (aP2-a) mice. Mice (aP2-a) exhibiting a pattern of obesity gene expression similar to humans were fed a low-Ca (0.4%)/high-fat/high-sucrose diet for six weeks, resulting in a 27% and twofold increase in body weight and total fat pad mass, respectively, with a twofold increase in adipocyte [Ca2+]i pad lib or Kcal-restricted (70% of ad lib) on this diet either unsupplemented (basal) or with 25% or 50% of the protein replaced by non-fat dry milk (medium or high) dairy or supplemented with CaCO3 to 1.2% Ca for six weeks. Adipocyte [Ca2+]i was unaffected by Kcal restriction but was reduced markedly by all three high Ca diets (290 vs. 130 nM, p2+]i and thereby reduce energy storage and increase thermogenesis during Kcal restriction.

Adipocytes↗
PubMed2000

Kheper, a novel ZFH/deltaEF1 family member, regulates the development of the neuroectoderm of zebrafish (Danio rerio).

Kheper is a novel member of the ZFH (zinc-finger and homeodomain protein)/deltaEF1 family in zebrafish. kheper transcripts are first detected in the epiblast of the dorsal blastoderm margin at the early gastrula stage and kheper is expressed in nearly all the neuroectoderm at later stages. kheper expression was expanded in noggin RNA-injected embryos and also in swirl mutant embryos and was reduced in bmp4 RNA-injected embryos and chordino mutant embryos, suggesting that kheper acts downstream of the neural inducers Noggin and Chordino. Overexpression of Kheper elicited ectopic expansion of the neuroectoderm-specific genes fkd3, hoxa-1, and eng3, and the ectopic expression of hoxa-1 was not inhibited by BMP4 overexpression. Kheper interacted with the transcriptional corepressors CtBP1 and CtBP2. Overexpression of a Kheper mutant lacking the homeodomain or of a VP16-Kheper fusion protein disturbed the development of the neuroectoderm and head structures. These data underscore the role of Kheper in the development of the neuroectoderm and indicate that Kheper acts as a transcriptional repressor.

Alcohol Oxidoreductases↗
PubMed2000

Nicotine is a potent blocker of the cardiac A-type K(+) channels. Effects on cloned Kv4.3 channels and native transient outward current.

BACKGROUND: Nicotine is a main constituent of cigarette smoke and smokeless tobacco, known to increase the risk of sudden cardiac death. This study aimed at establishing ionic mechanisms underlying potential electrophysiological effects of nicotine. METHODS AND RESULTS: Effects of nicotine on Kv4.3 and Kv4.2 channels expressed in Xenopus oocytes were studied at the whole-cell and single-channel levels. The effects of nicotine on the transient outward K(+) current (I:(to)) were studied by use of whole-cell patch-clamp techniques in canine ventricular myocytes. Nicotine potently inhibited Kv4 current. The concentration for half-maximal inhibition (IC(50)) was 40+/-4 nmol/L, and the current was abolished by 100 micromol/L nicotine. The IC(50) for block of native I:(to) was 270+/-43 nmol/L. The steady-state activation properties of Kv4.3 and I:(to) were unaltered by nicotine, whereas positive shifts of the inactivation curves were observed. Of the total inhibition of Kv4.3 and I:(to) by nicotine, 40% was due to tonic block and 60% was attributable to use-dependent block. Activation, inactivation, and reactivation kinetics were not significantly changed by nicotine. Nicotine reduced single-channel conductance, open probability, and open time but increased the closed time of Kv4.3. The effects of nicotine were not altered by antagonists to various neurotransmitter receptors, indicating direct effects on I:(to) channels. CONCLUSIONS: Nicotine is a potent inhibitor of cardiac A-type K(+) channels, with blockade probably due to block of closed and open channels. This action may contribute to the ability of nicotine to affect cardiac electrophysiology and induce arrhythmias.

Animals↗
PubMed2000

Role of intracellular calcium in human adipocyte differentiation.

Intracellular calcium ([Ca(2+)](i)) modulates adipocyte lipid metabolism and inhibits the early stages of murine adipogenesis. Consequently, we evaluated effects of increasing [Ca(2+)](i) in early and late stages of human adipocyte differentiation. Increasing [Ca(2+)](i) with either thapsigargin or A23187 at 0-1 h of differentiation markedly suppressed differentiation, with a 40-70% decrease in triglyceride accumulation and glycerol-3 phosphate dehydrogenase (GPDH) activity (P < 0.005). However, a 1-h pulse of either agent at 47-48 h only modestly inhibited differentiation. Sustained, mild stimulation of Ca(2+) influx with either agouti protein or 10 mM KCl-induced depolarization during 0-48 h of differentiation inhibited triglyceride accumulation and GPDH activity by 20-70% (P < 0.05) and markedly suppressed peroxisome proliferator-activated receptor gamma (PPARgamma) expression. These effects were reversed by Ca(2+) channel antagonism. In contrast, Ca(2+) pulses late in differentiation (71-72 h or 48-72 h) markedly increased these markers of differentiation. Thus increasing [Ca(2+)](i) appears to exert a biphasic regulatory role in human adipocyte differentiation, inhibiting the early stages while promoting the late stage of differentiation and lipid filling.

Adipocytes↗
PubMed2000

Ligand binding and structural properties of segments of GABAA receptor alpha 1 subunit overexpressed in Escherichia coli.

The gamma-aminobutyric acid, type A (GABA(A)), receptor is the target for numerous therapeutic compounds. In the present study, the Gln(28)-Leu(296), Gln(28)-Arg(276), Gln(28)-Arg(248), and Gln(28)-Glu(165) (numbering of bovine precursor protein) segments of its alpha(1) subunit were overexpressed in Escherichia coli, along with Cys(166)-Leu(296) produced previously, for structural analysis by circular dichroism and ligand binding studies by fluorescence spectroscopy. Results showed that the protein segments were rich in beta-sheet structures. Binding of the fluorescent benzodiazepine Bodipy-FL Ro-1986 was evident from fluorescence resonance energy transfer and fluorescence anisotropy measurements. The binding affinity was in the micromolar range. The binding was attributable more to Cys(166)-Leu(296) than to Gln(28)-Glu(165) and was inhibited by known central benzodiazepine site ligands. Three point mutations, Y187A, T234A, and Y237A, were found to perturb protein secondary structures. Studies with the single Trp mutants W198Y and W273Y indicated that Trp(273) was closer to the binding site than Trp(198).

Amino Acid Sequence↗
PubMed2000

The Arabidopsis thaliana salt tolerance gene SOS1 encodes a putative Na+/H+ antiporter.

In Arabidopsis thaliana, the SOS1 (Salt Overly Sensitive 1) locus is essential for Na(+) and K(+) homeostasis, and sos1 mutations render plants more sensitive to growth inhibition by high Na(+) and low K(+) environments. SOS1 is cloned and predicted to encode a 127-kDa protein with 12 transmembrane domains in the N-terminal part and a long hydrophilic cytoplasmic tail in the C-terminal part. The transmembrane region of SOS1 has significant sequence similarities to plasma membrane Na(+)/H(+) antiporters from bacteria and fungi. Sequence analysis of various sos1 mutant alleles reveals several residues and regions in the transmembrane as well as the tail parts that are critical for SOS1 function in plant salt tolerance. SOS1 gene expression in plants is up-regulated in response to NaCl stress. This up-regulation is abated in sos3 or sos2 mutant plants, suggesting that it is controlled by the SOS3/SOS2 regulatory pathway.

Alleles↗
PubMed2000

Template recognition of protein-imprinted polymer surfaces.

Synthetic materials capable of specifically recognizing proteins are important in separations, biosensors, and biomaterials. In this study, polysaccharide-like surfaces with tailored protein-binding nanocavities were prepared by a novel templating approach based on radiofrequency plasma deposition of thin films. The template-imprinted proteins included albumin, immunoglobulin, fibrinogen, lysozyme, ribonuclease A, alpha-lactalbumin, and glutamine synthetase. Transmission electron microscopy showed that nanometer-sized "pits" in the shape of imprinted protein were formed on the surfaces of template-imprinted polymer films. Electron spectroscopy for chemical analysis and time-of-flight secondary ion mass spectrometry indicated the saccharide covering of imprint surfaces and the removal of template proteins. (125)I-labeled protein adsorption from single solutions showed a similar amount of protein was adsorbed to its own imprint as to the imprint of another protein. However, more protein remained on the former surface than on the latter following elution with the detergents Tween 20 or sodium dodecyl sulfate. Competitive adsorption of a binary protein mixture showed a highly preferential adsorption of template protein to the corresponding imprint. This template recognition diminished as the number of protein-imprinted pits decreased. Structurally unstable proteins such as alpha-lactalbumin exhibited weaker template recognition that "robust" proteins such as lysozyme. The hypothesis that protein recognition is due to complementarity between the protein and its imprinted nanopit was supported by protein turnover experiments that showed template protein adsorbed to its own imprint was less readily displaced by a nontemplate protein.

Adsorption↗
PubMed2000

Catecholaminergic enzymes, vasopressin and oxytocin distribution in Siberian hamster brain.

Siberian hamsters exhibit marked seasonal changes in physiology and behavior that are triggered by the daylength and that can be mimicked in the laboratory by changing the photoperiod, making them a convenient and popular species for the study of regulatory biology. Because no atlas of neurotransmitter distribution exists for this species, the purpose of the present study was to map the distribution of cell bodies containing catecholaminergic synthetic enzymes (tyrosine hydroxylase and dopamine-beta-hydroxylase) and several neurotransmitters (arginine vasopressin and oxytocin) in Siberian hamster brain using immunocytochemistry. The distributions of these catecholaminergic synthetic enzymes and neurotransmitters largely were similar to those for Syrian hamsters with some notable differences. There were novel groups of neurotransmitter- or synthetic enzyme-immunoreactive neurons such as tyrosine hydroxylase-immunoreactive cells in the bed nucleus of the stria terminalis, dopamine-beta-hydroxylase-immunoreactive cells in the motor trigeminal, hypoglossal, and paraabducens nuclei, and arginine vasopressin- and oxytocin-immunoreactive cells within the nucleus of the diagonal band, dorsal hypothalamic area, and arcuate nucleus compared with Syrian hamsters. This is the first description of the distribution of cell bodies for some commonly studied catecholaminergic synthetic enzymes and peptides in Siberian hamsters.

Animals↗
PubMed2000

Genetic interference in Trypanosoma brucei by heritable and inducible double-stranded RNA.

The use of double-stranded RNA (dsRNA) to disrupt gene expression has become a powerful method of achieving RNA interference (RNAi) in a wide variety of organisms. However, in Trypanosoma brucei this tool is restricted to transient interference, because the dsRNA is not stably maintained and its effects are diminished and eventually lost during cellular division. Here, we show that genetic interference by dsRNA can be achieved in a heritable and inducible fashion. To show this, we established stable cell lines expressing dsRNA in the form of stem-loop structures under the control of a tetracycline-inducible promoter. Targeting a-tubulin and actin mRNA resulted in potent and specific mRNA degradation as previously observed in transient interference. Surprisingly, 10-fold down regulation of actin mRNA was not fatal to trypanosomes. This type of approach could be applied to study RNAi in other organisms that are difficult to microinject or electroporate. Furthermore, to quickly probe the consequences of RNAi for a given gene we established a highly efficient in vivo T7 RNA polymerase system for expression of dsRNA. Using the alpha-tubulin test system we obtained greater than 98% transfection efficiency and the RNAi response lasted at least two to three cell generations. These new developments make it possible to initiate the molecular dissection of RNAi both biochemically and genetically.

Actins↗
PubMed2000

The crystal structure of yeast phenylalanine tRNA at 1.93 A resolution: a classic structure revisited.

The crystal structure of the monoclinic form of yeast phenylalanine tRNA has been redetermined at a resolution of 1.93 A. The structure of yeast tRNAphe described here is more accurate than its predecessors not only because it incorporates higher resolution data, but also because it has been refined using techniques that had not been developed when its predecessors were determined more than 20 years ago. The 1.93 A resolution version of this structure differs interestingly from its predecessors in its details. In loop regions particularly, the backbone torsion angles in the new structure are not the same as those reported earlier. Several new divalent cation binding sites have been identified, and the water structure that has emerged is also different.

Base Sequence↗
PubMed2000

A new twist in trypanosome RNA metabolism: cis-splicing of pre-mRNA.

It has been known for almost a decade and a half that in trypanosomes all mRNAs are trans-spliced by addition to the 5' end of the spliced leader (SL) sequence. During the same time period the conviction developed that classical cis-splicing introns are not present in the trypanosome genome and that the trypanosome gene arrangement is highly compact with small intergenic regions separating one gene from the next. We have now discovered that these tenets are no longer true. Poly(A) polymerase (PAP) genes in Trypanosoma brucei and Trypanosoma cruzi are split by intervening sequences of 653 and 302 nt, respectively. The intervening sequences occur at identical positions in both organisms and obey the GT/AG rule of cis-splicing introns. PAP mRNAs are trans-spliced at the very 5' end as well as internally at the 3' splice site of the intervening sequence. Interestingly, 11 nucleotide positions past the actual 5' splice site are conserved between the T. bruceiand T. cruzi introns. Point mutations in these conserved positions, as well as in the AG dinucleotide of the 3' splice site, abolish intron removal in vivo. Our results, together with the recent discovery of cis-splicing introns in Euglena gracilis, suggest that both trans- and cis-splicing are ancient acquisitions of the eukaryotic cell.

Amino Acid Sequence↗