Biomedical subjects

S Zhu

Publications and source records attributed to S Zhu.

At least 91 records · Page 5Linked to original sources

PubMed2001

[The mechanism of neuro-2a cell death induced by H2O2].

Reactive oxygen species (ROS), such as H2O2, can be produced by enzymes involved in electron leakage of respiration chain in mitochondria, and by neurochemical enzymes such as monoamine oxidase in neural cells. ROS are toxic to cells, and can result in cell death. ROS also play an important role in some diseases, especially in neurodegenerative diseases by yet unknown mechanisms. In the current research, the N-2a neuroblastoma cell was treated with H2O2, and the morphological changes of cell death were characterized. Our results show that N-2a cell death is different from classical apoptosis, but belongs type II nerve cell programmed death, which shows condensed chromatin within intact nuclear envelope and no apoptotic body. The chromatin DNA of dead cells shows no internucleosomal cleavage, as well as no requirement for caspase-3, 1 activity. However, the H2O2-induced N-2a cell death can be inhibited by Bcl-XL. It can be concluded that type II nerve cell death is the result of cell toxicity mediated by ROS. The results pave the way for further research of type II nerve cell death.

Animals↗

PubMed2001

[The clone and comparison of very virulent plus Marek's disease virus(vv+ DMV)648 strain glycoprotein E(gE) gene].

The glycoprotein E(gE) gene of very virulent plus Marek's Disease (vv+ MDV) 648 strain was amplified by polymerase chain reaction (PCR) and cloned into pUC18 vector. The gE sequence was determined and analysed. The whole length of 648 strain gE gene is 1494 base pairs. The protein encoded by gE gene has several features characteristic of a membrane-associated glycoprotein. It contains eight potential glycosylation sites, a markedly hydrophobic region at the N terminus that could function as a signal peptide and a hydrophobic segment (aa 391-419) at C terminus that could function as a transmembrane anchor element. Comparison of the gE between 648 strain and virulent MDV (vMDV) GA strain revealed that gE sequence is conserved in MDV serotype 1, there are only two basepairs different, (at bp 512 and 1472), which induce two amino acids changed respectively (at aa 171 and 491). The function of 648 strain gE and the difference of gE between 648 strain and GA strain is on study.

Amino Acid Sequence↗

PubMed2001

[Irradiation of 235 uranium on the growth, behavior and some biochemical changes of brain in neonatal rats].

The effects of enriched uranium on growth, behavior and biochemical changes of brain in neonatal Wistar rats was studied. Neonatal rats were irradiated with a single injection of 2 microliters enriched uranium (containing 0, 1, 5 and 10 micrograms of 235U) into left lateral ventricle of brain at the first day (< 24 h) after birth. The growth and neurobehavior development of the rats was delay and abnormal. The microautoradiographic tracing technique showed that the radionuclide was mainly accumulated in the nucleus, also appeared in the cytoplasm of cells and between cells. The activity of superoxide dismutase (SOD) and the level of endothelin (ET) of cerebellum, cerebral cortex, hippocampus and diencephalons of brain after exposure to alpha irradiation were examined with radioimmunoassay. The data indicated that SOD and ET was elevated by low dose irradiation and distinctly inhibited by high dose irradiation. It was concluded that alpha irradiation could have damages on the developing brain of neonatal rats characterized by changing the sensibility, fragility and compensation of nerve cells.

Animals↗

PubMed2001

[Antibacterial activity of 20 kinds of Chinese medicinal materials for Helicobacter pylori in vitro].

OBJECTIVE: To study the antibacterial activity of 20 Chinese medicinal materials for helicobacter pylori in vitro and the culture of hylicobacter pylori. METHODS: Doubled-diluted method and tomato juice culture medium were adopted. RESULTS: The detecting ratio of tomato juice culture medium to hylicobacter pylori was equal to that of skirrow culture medium; Radix Scutellariae, Flos Lonicerae, Radix Isatidis, Indigo Naturalis, Fructus Chebulae, Semen Ginkgo, Cortex Phellodendri, Rhizoma Corydalis and Cortex Fraxini have obvious effect of antibacterium to hyliocobater pylori.

Anti-Bacterial Agents↗

PubMed2001

[Rapid construction of directional cDNA library from human nasopharynx].

OBJECTIVE: To construct a directional cDNA library from human adult nasopharynx by SMART (switching mechanism at 5' end of RNA transcript) technique. METHODS: The total RNA was separated from human adult nasopharynx epithelial tissue and the first-strand cDNA was synthesized through reverse transcription by a modified oligo(dT) primer(contained sfi IB site) while the SMART oligonucleotide(contained sfi IA site) was utilized as a template so that the first-strand cDNA could be extended over the 5' end of mRNA. The double-strand cDNA was amplified by LD-PCR(long-distance PCR) with the above two primers and then digested by sfi I (IA & IB) restriction enzyme. After cDNA size fractionation through CHROMA SPIN column, the double-strand cDNA was ligated into the sfi I-digested lambda TripIEx2 vector and then the recombinant DNA was packaged in vitro. RESULTS: The unamplified human adult nasopharynx cDNA library consists of 1.5 x 10(6) independent clones in which the percentage of recombinant clones is about 100%. The titer of the amplified cDNA library is 3.8 x 10(9) pfu/ml and the average exogenous inserts of the recombinants is 1.5 kb. CONCLUSION: These results shows that the human adult nasopharynx cDNA library has an excellent quality and lays solid foundation for screening and cloning new tumor suppressor genes of nasopharyngeal carcinoma(NPC) and tissue-specific genes of human nasopharynx.

Adult↗

PubMed2000

Antimutagenic effects of wheat bran diet through modification of xenobiotic metabolising enzymes.

Diets containing wheat bran (WB) protect against cancers of the colon or breast in rats, and may be beneficial in humans. In a previous study of rats treated with the carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), inclusion of 10% wheat bran in the diet led to an apparent reduction in IQ metabolites but not of intact IQ in plasma. In the present study, male Wistar rats were fed diets containing 0, 10 or 20% wheat bran, and effects on xenobiotic metabolising enzymes compared. Wheat bran-supplementation showed differential effects on phase I enzymes, significantly increasing the activity of hepatic cytochrome P450 isozyme CYP3A2, but slightly reducing the activity of CYP1A1/2. The activities of both hepatic phase II detoxification enzymes glutathione-S-transferase and glucuronosyl transferase were also reduced. Western blotting revealed similar effects on expression of the proteins. Interestingly, the expression of xenobiotic metabolising enzymes (XME) in the colon appeared to be modulated independently of hepatic XME. Although the wheat bran-supplemented diet still led to an increased expression of CYP3A, it now slightly increased CYP1A in the colon. However, 20% wheat bran significantly increased the expression of both glutathione transferase isozymes, GST A1 & A2, in the colon. Natures Gold (NG) is a commercial wheat bran derivative which is lower than wheat bran in dietary fibre, but enriched in vitamins, minerals and various phytochemicals. Dietary supplementation with 20% Natures Gold led to similar trends as seen in wheat bran-fed rats, but more potent effects in both hepatic and colonic enzymes. The significance of these changes for activation of carcinogens to mutagenic metabolites was investigated using the Salmonella/mammalian microsome mutagenicity test. The activation of IQ and benzo[a]pyrene, but not cyclophosphamide, to a mutagen by hepatic S9 from wheat bran-fed or Natures Gold-fed rats was significantly reduced compared with S9 from animals on a diet lacking wheat bran. We suggest that modulation of xenobiotic metabolising enzymes may be an important component of cancer protection by wheat bran, and this effect may relate to micronutrients or cancer-protective non-nutrient phytochemicals rather more than to dietary fibre.

Animals↗

PubMed2000

A glia-derived signal regulating neuronal differentiation.

Astrocytes are present in large numbers in the nervous system, are associated with synapses, and propagate ionic signals. Astrocytes influence neuronal physiology by responding to and releasing neurotransmitters, but the mechanisms that establish the close interaction between these cells are not defined. Here we use hippocampal neurons in culture to demonstrate that vasoactive intestinal polypeptide (VIP) promotes neuronal differentiation through activity-dependent neurotrophic factor (ADNF), a protein secreted by VIP-stimulated astroglia. ADNF is produced by glial cells and acts directly on neurons to promote glutamate responses and morphological development. ADNF causes secretion of neurotrophin 3 (NT-3), and both proteins regulate NMDA receptor subunit 2A (NR2A) and NR2B. These data suggest that the VIP-ADNF-NT-3 neuronal-glial pathway regulates glutamate responses from an early stage in the synaptic development of excitatory neurons and may also contribute to the known effects of VIP on learning and behavior in the adult nervous system.

Animals↗

PubMed2000

Alpha-fetoprotein-derived antiestrotrophic octapeptide.

Alpha-fetoprotein (AFP) is a major serum protein produced during fetal development. Experimental findings suggest that AFP has antiestrotrophic activity and that it can be developed as a therapeutic agent to treat existing estrogen-dependent breast cancer or to prevent premalignant foci from developing into breast cancer. The antiestrotrophic activity of AFP was reported to be localized to a peptide consisting of amino acids 447-480, a 34-mer peptide termed P447. A series of parsings and substitutions of amino acids in the P447 sequence was intended to identify the shortest analog which retained antiestrotrophic activity. Peptides related to P447 were generated using solid phase peptide synthesis. Several shorter peptides, including an 8-mer called P472-2 (amino acids 472-479, peptide sequence EMTPVNPG), retained activity, whereas peptides shorter than eight amino acid residues were inactive. The dose-related antiestrotrophic activity of AFP-derived peptides was determined in an immature mouse uterine growth assay that measures their ability to inhibit estradiol-stimulated uterine growth. In this assay, the maximal inhibitory activities exhibited by peptide P472-2 (49%), by peptide P447 (45%), and by intact AFP (35-45%) were comparable. The octapeptide P472-2 was also active against estradiol-stimulated growth of T47D human breast cancer cells in culture. These data suggest that peptide P472-2 is the minimal sequence in AFP, which retains the antiestrotrophic activity found with the full-length molecule. The synthetic nature and defined structure of this 8-mer peptide suggest that it can be developed into a new drug which opposes the action of estrogen, perhaps including the promotional effects of estradiol in the development of human breast cancer.

Amino Acid Sequence↗

PubMed2000

Variant genotypes of FcgammaRIIIA influence the development of Kaposi's sarcoma in HIV-infected men.

Disturbances in inflammatory cytokine production and immune regulation coupled with human herpesvirus-8 (HHV-8) infection underlie the current understanding of the pathogenesis of Kaposi's sarcoma (KS), the most common HIV-associated malignancy. The low affinity Fc gamma receptors (FcgammaR) for IgG link humoral and cellular immunity by mediating interaction between antibodies and effector cells, such as phagocytes and natural killer cells. We examined the frequency of polymorphic forms of the low affinity FcgammaRs, FcgammaRIIA, FcgammaRIIIA, and FcgammaRIIIB in 2 cohorts of HIV-infected men with KS and found that the FcgammaRIIIA genotype exerts a significant influence on susceptibility to or protection from KS. The FF genotype was underrepresented in patients with KS, whereas the VF genotype was associated with development of KS. A similar association was observed between FcgammaRIIIA genotypes and HHV-8 seropositivity. These observations suggest a possible role for FcgammaRIIIA in the development of KS during HIV infection.

Acquired Immunodeficiency Syndrome↗

PubMed2000

MSY2: a slowly evolving minisatellite on the human Y chromosome which provides a useful polymorphic marker in Chinese populations.

We present the second human Y-specific minisatellite, MSY2 (DYS440). It consists of three or four copies of a 99-110bp repeat unit and is located about 1kb upstream of the DBY gene. The most common allele contains four units, but a three-unit allele has arisen on at least four occasions; in chimpanzees and orangutans, MSY2 contains only two units. It is therefore evolving slowly and provides a particularly useful polymorphic marker for Chinese populations.

Alleles↗

PubMed2000

cDNA cloning and functional expression of growth hormone receptor from soft-shelled turtle (Pelodiscus sinensis japonicus).

The growth hormone receptor (GHR) cDNA was cloned from the liver of soft-shelled turtle (Pelodiscus sinensis japonicus) using the polymerase chain reaction (PCR). Although GHR has been cloned from several mammalian and avian species, this is the first description of the reptilian receptor. As deduced from the nucleotide sequence, the precursor GHR of soft-shelled turtle (tGHR) is a protein of 615 amino acids which presents 72% identity with the chicken receptor and 57-64% identity with GHRs of several mammals. The tGHR expressed in COS-7 cells specifically bound human growth hormone (hGH) and was able to transduce an activation of transcription in the transfected cells. Binding of (125)I-hGH to the expressed receptor was decreased by the addition of excess unlabeled hGH, pig GH, and bream GH but not by pig insulin. The open reading frame of tGHR cDNA was inserted into the pSINrep/gfp (green fluorescence protein) vector and the tGHR-gfp fusion protein was stably expressed in baby hamster kidney (BHK) cells. Confocal imaging showed that tGHR-gfp was largely concentrated on the plasma membrane. Western blot analysis and deglycosylation treatment with PNGase F demonstrated that tGHR was a glycoprotein in BHK cells.

Amino Acid Sequence↗

PubMed2000

Flow cytometric analysis of DNA content in parotid tumor and its contiguous acini.

To investigate the relationship between proliferative capacity of salivary gland cells in contiguous acini of parotid tumors and recurrent neoplasma, DNA contents of 30 fresh specimens of parotid were studied by using cytometry in tumors, normal and shallow or deep lobe acini of the masses. The results showed that the DI was 1.369, S% 16.95, PI 26.18 in malignant tumors; DI was 1.171, S% 12.41, PI 15.54 in recurrent pleomorphic adenoma; DI was 1.141, S% 12. 74, PI 13.07 in pleomorphic adenoma, DI was 0.999, S% 5.10, PI 8.00 in normal acini. Analysis of variance showed there was a significant difference (P < 0.01). The average DNA contents of shallow on deep lobe of contiguous tumors was 1.08 in DI, 10.65 in S%, 13.49 in PI in malignant tumor, 1.06 in DI, 8.96 in S% and 9.85 in PI in pleomorphic adenoma, which were all higher than in normal acini (P > 0.05). It was concluded that the levels of DI and S% of parotid tumor and its contiguous acini are related to degree of malignancy or recurrent condition of the tumors, suggesting contiguous acini of parotid tumors had the strong capacity of proliferation, which might play an important role in recurrent or malignant change of the parotid tumors.

Adenoma, Pleomorphic↗

PubMed2000

Immunoblot analysis of CD34 expression in histologically diverse neoplasms.

CD34 is a heavily glycosylated transmembrane protein of approximately 110 kd whose function is essentially uncharacterized. First identified in a myeloid leukemia cell line, immunohistological reactivity with anti-CD34 antibodies is also encountered in a histologically diverse subset of nonhematolymphoid neoplasms including angiosarcoma, solitary fibrous tumors, epithelioid sarcomas, spindle cell lipomas, dermatofibrosarcoma protuberans, and myofibroblastomas. Immunohistological reactivity for CD34 in hematopoietic stem cells and endothelial cells has been shown to correspond to the expression of the CD34 protein. With the exception of gastrointestinal stromal tumors, CD34 protein expression has not been investigated in other CD34 immunohistologically reactive nonhematolymphoid neoplasms. We undertook this study to examine whether the observed reactivity for anti-CD34 antibodies in apparently unrelated tumors is due to the expression of the same protein or whether shared epitopes elaborated by other proteins could account for this reactivity. Immunoblot analyses with anti-CD34 antibodies of six different CD34 immunohistologically reactive lesions show the same approximately 110-kd molecular weight protein. In addition, two cases of dermatofibrosarcoma protuberans show double bands at approximately 110 kd. Laser-capture microdissection of CD34 immunohistologically reactive epithelioid sarcoma and nonreactive epidermal cells illustrates that this reactivity is specific to tumor cells. These results show that the observed immunohistological reactivity with anti-CD34 antibodies is due to the expression of the CD34 protein and not to shared epitopes on unrelated proteins.

Adolescent↗

PubMed2000

Evaluation of 3-D colour Doppler ultrasound for the measurement of proximal isovelocity surface area.

Three-dimensional (3-D) colour Doppler ultrasound (US) enables flow rate estimation across a diseased valve without the need for a priori geometric assumptions. This study quantitatively evaluates the accuracy of 3-D colour Doppler US for measuring the flow rate (8. 3-75 mL/s) through a valve using the proximal flow convergence field. Flow rate measurements by this 3-D technique underestimate flow through finite circular orifices due to two major sources of error: 1. surface area slicing technique (18.3% +/- 3.8%) and 2. Doppler angle effect (41.0% +/- 1.5%). Combined total underestimation is 51% +/- 3.3%. To utilize 3-D US, the development of an improved proximal isovelocity surface area (PISA) measurement technique and a correction factor for the Doppler angle effect is required.

Blood Flow Velocity↗

PubMed2000

Smoking cessation with and without assistance: a population-based analysis.

OBJECTIVE: To examine usage rates of smoking-cessation assistance and to compare the success rate of those who used assistance with the success rate of those who did not. METHODS: The data come from the 1996 California Tobacco Survey, a random sample of 4480 individuals (18 years or older) who tried to quit smoking in the 12 months before the survey. We calculated population estimates for demographics, smoking histories, rate of using assistance, and abstinence rates. RESULTS: One fifth (19.9%) of those who attempted to quit smoking used one or more forms of assistance: self-help, counseling, and/or nicotine replacement therapy (NRT). Heavy smokers were more likely to use assistance than were light smokers. Women were more likely to use assistance than were men, and usage increased with age. Whites were more likely to use NRT than were other ethnic groups. Overall, those who used assistance had a higher success rate than those who did not; the 12-month abstinence rates were 15.2% and 7.0%, respectively. CONCLUSIONS: Use of assistance for smoking cessation has increased over recent years, from 7.9% in 1986 to 19.9% in 1996. The use of assistance is associated with a greater success rate. Anti-tobacco campaigns in California and increased availability of multiple forms of assistance probably facilitated the use of assistance and successful quitting for those using assistance.

Adolescent↗

PubMed2000

Guaiane dimers and germacranolide from Artemisia caruifolia.

One new germacranolide (named caruifolin A) and three new guaiane dimers (caruifolins B-D), together with six known compounds, were isolated from the aerial parts of Artemisia caruifolia. The structures were determined by chemical and spectroscopic methods.

Anti-HIV Agents↗

PubMed2000

Minocycline inhibits caspase-1 and caspase-3 expression and delays mortality in a transgenic mouse model of Huntington disease.

Huntington disease is an autosomal dominant neurodegenerative disease with no effective treatment. Minocycline is a tetracycline derivative with proven safety. After ischemia, minocycline inhibits caspase-1 and inducible nitric oxide synthetase upregulation, and reduces infarction. As caspase-1 and nitric oxide seem to play a role in Huntington disease, we evaluated the therapeutic efficacy of minocycline in the R6/2 mouse model of Huntington disease. We report that minocycline delays disease progression, inhibits caspase-1 and caspase-3 mRNA upregulation, and decreases inducible nitric oxide synthetase activity. In addition, effective pharmacotherapy in R6/2 mice requires caspase-1 and caspase-3 inhibition. This is the first demonstration of caspase-1 and caspase-3 transcriptional regulation in a Huntington disease model.

Animals↗

PubMed2000

Cerebral arteriovenous malformations associated with aneurysms--a report of 10 cases and literature review.

We analysed 10 cases of arteriovenous malformations (AVMs) associated with aneurysms and reviewed the literature in order to confirm the clinical characteristics of AVMs associated with aneurysms. The mean incidence of aneurysms in our AVM population was 9.1% and the average age was 38 years. The ratio of male to female was 1.3 to 1. The aneurysms (40-96%) were often located on a feeding artery and seldom (23%) at an arterial bifurcation. The mortality rate was 0-26% in surgically managed patients and 38-60% in conservatively treated patients. The combination of intracranial vascular lesions is not rare. Most patients presented with symptoms referable to their AVMs. Treating both lesions in a single operation is the best option. The prognoses for most patients was good.

Adolescent↗