Biomedical subjects

Z Yu

Publications and source records attributed to Z Yu.

At least 19 recordsLinked to original sources

PubMed2001

Radiation induced apoptosis in ataxia telangiectasia homozygote, heterozygote and normal cells.

Recent reports suggest that the radiation-induced, p53-dependent, apoptotic response is aberrant in ataxia telangiectasia (AT) cells. We investigated the possibility that an aberrant apoptotic response to ionizing radiation may also be the characteristic of AT heterozygotes and may facilitate in discriminating AT heterozygotes from the general population. Log phase, Epstein Barr virus (EBV) transformed lymphoblastoid cell lines and primary lymphocytes from three AT families were irradiated and the apoptotic response at 30h post radiation was measured by flow cytometry using TUNEL and hypodiploid methods. Our results show that the apoptotic response of AT homozygote (ATM-/-), AT heterozygote (ATM+/-) and normal cells (ATM+/+) to ionizing radiation, measured by the hypodiploid and TUNEL methods using flow cytometry, is dose and time dependent. Furthermore, this response is paradoxical in that ATM (-/-) lymphoblastoid cells were characterized by a reduced post radiation apoptotic response compared to their normal counterparts. Heterozygote (ATM+/-) lymphoblastoid cells displayed an intermediate response to ionizing radiation. In contrast, primary, non-transformed AT cells exhibited the same apoptotic response as their normal counterparts. Our results thus indicate that pre-radiation, EBV-transformed, lymphoblastoid cell lines from individual families may be useful in discriminating ATM status, but patient-derived, primary AT homozygous, heterozygous and normal primary cultured lymphocytes cannot be discriminated by this assay.

Apoptosis↗

PubMed2001

Identification and characterization of S2V, a novel putative siglec that contains two V set Ig-like domains and recruits protein-tyrosine phosphatases SHPs.

We describe the molecular cloning and characterization of S2V, a novel sialic acid binding immunoglobulin-like lectin. The cDNA of S2V encodes a type 1 transmembrane protein with four extracellular immunoglobulin-like (Ig-like) domains and a cytoplasmic tail bearing a typical immunoreceptor tyrosine-based inhibitory motif (ITIM) and an ITIM-like motif. A unique feature of S2V is the presence of two V-set Ig-like domains responsible for the binding to sialic acid, whereas all other known siglecs possess only one. S2V is predominantly expressed in macrophage. In vivo S2V was tyrosine-phosphorylated when co-expressed with exogenous c-Src kinase. Upon tyrosine phosphorylation, S2V recruits both Src homology 2 (SH2) domain-containing protein-tyrosine phosphatases SHP-1 and SHP-2, two important inhibitory regulators of immunoreceptor signal transduction. These findings suggest that S2V is involved in the negative regulation of the signaling in macrophage by functioning as an inhibitory receptor. When expressed in COS-7 cells, S2V was able to mediate sialic acid-dependent binding to human red blood cells, suggesting that S2V may function through cell-cell interaction.

Amino Acid Sequence↗

PubMed2001

mSiglec-E, a novel mouse CD33-related siglec (sialic acid-binding immunoglobulin-like lectin) that recruits Src homology 2 (SH2)-domain-containing protein tyrosine phosphatases SHP-1 and SHP-2.

The sialic acid-binding immunoglobulin-like lectins (siglecs) represent a recently defined distinct subset of the immunoglobulin superfamily. By using the Src homology 2 (SH2)-domain-containing protein tyrosine phosphatase SHP-1 as bait in a yeast two-hybrid screen, we have identified a new member of the mouse siglec family, mSiglec-E. The mSiglec-E cDNA encodes a protein of 467 amino acids that contains three extracellular immunoglobulin-like domains, a transmembrane region and a cytoplasmic tail bearing two immunoreceptor tyrosine-based inhibitory motifs (ITIMs). mSiglec-E is highly expressed in mouse spleen, a tissue rich in leucocytes. The ITIMs of mSiglec-E can recruit SHP-1 and SHP-2, two inhibitory regulators of immunoreceptor signal transduction. This suggests that the function of mSiglec-E is probably an involvement in haematopoietic cells and the immune system as an inhibitory receptor. When expressed in COS-7 cells, mSiglec-E was able to mediate sialic acid-dependent binding to human red blood cells, suggesting that mSiglec-E may function through cell-cell interactions. In comparison with the known members of the siglec family, mSiglec-E exhibits a high degree of sequence similarity to both human siglec-7 and siglec-9. The gene encoding mSiglec-E is localized in the same chromosome as that encoding mouse CD33. Phylogenetic analysis reveals that neither mouse mSiglec-E nor CD33 shows a clear relationship with any human siglecs so far identified.

Amino Acid Sequence↗

PubMed2001

The neurotoxic prion peptide fragment PrP(106-126) is a chemotactic agonist for the G protein-coupled receptor formyl peptide receptor-like 1.

Prion diseases are transmissible and fatal neurodegenerative disorders which involve infiltration and activation of mononuclear phagocytes at the brain lesions. A 20-aa acid fragment of the human cellular prion protein, PrP(106-126), was reported to mimic the biological activity of the pathologic isoform of prion and activates mononuclear phagocytes. The cell surface receptor(s) mediating the activity of PrP(106-126) is unknown. In this study, we show that PrP(106-126) is chemotactic for human monocytes through the use of a G protein-coupled receptor formyl peptide receptor-like 1 (FPRL1), which has been reported to interact with a diverse array of exogenous or endogenous ligands. Upon stimulation by PrP(106-126), FPRL1 underwent a rapid internalization and, furthermore, PrP(106-126) enhanced monocyte production of proinflammatory cytokines, which was inhibited by pertussis toxin. Thus, FPRL1 may act as a "pattern recognition" receptor that interacts with multiple pathologic agents and may be involved in the proinflammatory process of prion diseases.

Animals↗

PubMed2001

The magnesium-ene cyclization stereochemically directed by an allylic oxyanionic group and its application to a highly stereoselective synthesis of (+/-)-matatabiether. Allylmagnesium compounds by reductive magnesiation of allyl phenyl sulfides.

The first example of a magnesium-ene cyclization stereochemically directed by an allylic oxyanionic group is demonstrated by a highly stereoselective synthesis of the bicyclic terpene matatabiether 10. The synthetic method is particularly valuable, not only because of the stereochemical control and the utility of the versatile hydroxyl group introduced into the product, but also because the precursor of the allylmagnesium is an allyl phenyl sulfide, which is more stable and more easily prepared in a connective fashion than the usual allyl halide precursor. Since the presence of lithium ions encourages undesirable proton transfer to the cyclized organometallic and is detrimental to the stereochemical control, the conversion of the allylic thioether to the allylmagnesium utilizes a lithium-free method involving direct reductive magnesiation in the presence of the magnesium-anthracene complex.

Journal Article↗

PubMed2001

Radiobiological effects of a low-energy ion beam on wheat.

The radiobiological effects of a low-energy nitrogen ion (N+) beam on wheat were studied, particularly with regard to the induction of chromosome aberrations. The results demonstrated that the three test varieties showed different sensitivities to ion implantation, and a higher dose of ion implantation had a marked effect on the germination and survival rate of the seeds exposed. The germination rate and survival rate curve basically followed a similar trend in the same variety. Cytological analysis indicated that ion beams were effective in producing chromosome aberrations. The frequencies of mitotic or meiotic cells with chromosome aberrations increased linearly with increasing doses. The aberration types included, for example, acentric fragments, chromosome deletions, lagging chromosomes, chromosome bridges and micronuclei. In the root tip cells, aberrations chiefly consisted of acentric fragments and deletions. Chromosome bridges and lagging chromosomes were the main aberration phenomena observed in the pollen mother cells. The highest frequencies of root tip cells and pollen mother cells with chromosome aberrations were 15.2% and 39.8%, respectively. Changes in morphology and mutant were also observed in the plants derived from exposed seeds.

Chromosome Aberrations↗

PubMed2001

Bioaugmentation with resin-acid-degrading bacteria enhances resin acid removal in sequencing batch reactors treating pulp mill effluents.

Resin acids are the major toxicants in pulp and paper mill effluents (PPMEs), and they form pitch interfering with papermaking. Efficient and reliable resin acid removal is critically important to prevent toxicity discharge and ensure proper functioning of paper machines. Two resin-acid-degrading bacteria, Pseudomonas abietaniphila BKME-9 and Zoogloea resiniphila DhA-35, were tested in laboratory sequencing batch reactors (SBRs) for their ability to enhance resin acid removal by biomass from a full-scale biotreatment system treating PPMEs. Both bacteria enhanced resin acid removal but not removal of total organic carbon (TOC) by either pH-shocked or starved activated sludge. These two bacteria also increased resin acid removal when the sludge was given high concentration (200 microM) of resin acid. A most-probable-number polymerase chain reaction (MPN-PCR) assay showed that these two bacteria were initially not detectable (detection limit: 10(2) bacterial cells/ml) in the sludge community and were persistent after inoculation. Both bacteria did not substantially change the indigenous microbial community composition, as assayed by ribosomal intergenic spacer analysis (RISA). Our results suggest that it is feasible and potentially useful to enhance resin acid removal by bioaugmentation using resin-acid-degrading bacteria such as BKME-9 and DhA-35.

Abietanes↗

PubMed2001

A comparison of whole wheat, refined wheat and wheat bran as inhibitors of heterocyclic amines in the Salmonella mutagenicity assay and in the rat colonic aberrant crypt focus assay.

Refined wheat, unrefined whole wheat, and wheat bran were studied for their ability to protect against heterocyclic amines (HCAs) in vitro and in vivo. Wheat bran, which binds HCAs in vitro, as well as refined wheat and unrefined whole wheat, inhibited the mutagenic activities of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) when they were co-incubated and the supernatant (minus grain) was added to the Salmonella assay. The water-soluble fraction alone from refined and unrefined wheat, but not bran, also inhibited against these mutagens in vitro. In vivo, AIN-93G diets containing refined wheat or unrefined wheat were examined for their ability to inhibit IQ-induced colonic aberrant crypt foci (ACF) in the Fischer 344 rat. A slight increase in the number of AC/ACF (aberrant crypts/ACF) was seen after 16 weeks in rats treated post-initiation with refined wheat (P < 0.05), and fewer foci with two or three aberrant crypts (ACF-2) were found in rats given unrefined whole wheat post-initiation compared with animals treated with the same diet during the initiation phase (P < 0.05). There was no significant difference in the profile of IQ urinary metabolites or excretion of promutagens 0-48 h after carcinogen dosing, and grains had no effect on hepatic cytochrome P4501A1 (CYP1A1), CYP1A2, aryl sulfotransferase or N-acetyltransferase activities; however, a slightly higher UDP-glucuronosyl transferase activity was observed in rats fed unrefined wheat compared with refined wheat diets (P < 0.05). Thus, despite their antimutagenic activities in vitro, only marginal effects were seen with refined and unrefined wheat in vivo with respect to hepatic enzyme activities, carcinogen metabolism and IQ-induced ACF in the rat colon.

Amines↗

PubMed2001

A 5-bp deletion in ELOVL4 is associated with two related forms of autosomal dominant macular dystrophy.

Stargardt-like macular dystrophy (STGD3, MIM 600110) and autosomal dominant macular dystrophy (adMD) are inherited forms of macular degeneration characterized by decreased visual acuity, macular atrophy and extensive fundus flecks. Genetic mapping data suggest that mutations in a single gene may be responsible for both conditions, already known to bear clinical resemblance. Here we limit the minimum genetic region for STGD3 and adMD to a 0.6-cM interval by recombination breakpoint mapping and identify a single 5-bp deletion within the protein-coding region of a new retinal photoreceptor-specific gene, ELOVL4, in all affected members of STGD3 and adMD families. Bioinformatic analysis of ELOVL4 revealed that it has homology to a group of yeast proteins that function in the biosynthesis of very long chain fatty acids. Our results are therefore the first to implicate the biosynthesis of fatty acids in the pathogenesis of inherited macular degeneration.

Amino Acid Sequence↗

PubMed2001

Reawakening the dragon: changing patterns of opiate use in Asia, with particular emphasis on China's Yunnan province.

Asian countries adjacent to the Golden Triangle and their neighbors have witnessed an evolution in "drug abuse" from traditional opium smoking to heroin eating, smoking, and finally heroin injection. A recent study of 630 heroin users was conducted in China's Yunnan Province, located close to the Golden Triangle. Data collected between August 1997 and February 1998 indicate injecting heroin users, in comparison to noninjectors, were more likely to have used drugs for a longer period of time, and to use drugs more frequently everyday. Other major differences existed between urban and rural subjects, especially highlighting differences between men and women. Women comprised a much higher proportion of urban subjects than rural subjects. Rural injectors were much more likely to be male, but urban injectors were almost evenly split between men and women. The emerging epidemic of heroin use in China and the continuing substance abuse problem in the United States provide an opportunity for collaborative research of mutual benefit.

Acquired Immunodeficiency Syndrome↗

PubMed2001

Bacterial diversity and community structure in an aerated lagoon revealed by ribosomal intergenic spacer analyses and 16S ribosomal DNA sequencing.

We investigated the bacterial community structure in an aerated plug-flow lagoon treating pulp and paper mill effluent. For this investigation, we developed a composite method based on analyses of PCR amplicons containing the ribosomal intergenic spacer (RIS) and its flanking partial 16S rRNA gene. Community percent similarity was determined on the basis of RIS length polymorphism. A community succession was evident in the lagoon, indicated by a progressive community transition through seven sample locations. The most abrupt changes in community structure were associated with a temperature change from 39 to 35 degrees C and with increases in dissolved oxygen. The temporal differences in community structure, based on summer and winter samplings, were greater than the spatial differences during either season. Clone libraries of rDNA-RIS amplicons were constructed from each of three summer samples. Among 90 clones analyzed (30 clones from each sample), 56 phylotypes were distinguished by restriction fragment length polymorphism. Indices of phylotype richness, evenness, and diversity all increased in clone libraries from the beginning to the end of the lagoon. A representative clone of each phylotype was phylogenetically analyzed on the basis of its partial 16S rRNA gene sequence (ca. 450 bp). Phylogenetic analysis confirmed the increase in diversity and further indicated increasing richness of bacterial divisions. Pioneers in the community spatial succession appeared to include thermotolerant, microaerophilic methanol-oxidizing bacteria related to the genus Methylobacillus, as well as thermotolerant, microaerophilic nitrogen-fixing bacteria related to the genus Azospirillum.

Bacteria↗

PubMed2001

Targeted random mutagenesis to identify functionally important residues in the D2 protein of photosystem II in Synechocystis sp. strain PCC 6803.

To identify important residues in the D2 protein of photosystem II (PSII) in the cyanobacterium Synechocystis sp. strain PCC 6803, we randomly mutagenized a region of psbDI (coding for a 96-residue-long C-terminal part of D2) with sodium bisulfite. Mutagenized plasmids were introduced into a Synechocystis sp. strain PCC 6803 mutant that lacks both psbD genes, and mutants with impaired PSII function were selected. Nine D2 residues were identified that are important for PSII stability and/or function, as their mutation led to impairment of photoautotrophic growth. Five of these residues are likely to be involved in the formation of the Q(A)-binding niche; these are Ala249, Ser254, Gly258, Ala260, and His268. Three others (Gly278, Ser283, and Gly288) are in transmembrane alpha-helix E, and their alteration leads to destabilization of PSII but not to major functional alterations of the remaining centers, indicating that they are unlikely to interact directly with cofactors. In the C-terminal lumenal tail of D2, only one residue (Arg294) was identified as functionally important for PSII. However, from the number of mutants generated it is likely that most or all of the 70 residues that are susceptible to bisulfite mutagenesis have been altered at least once. The fact that mutations in most of these residues have not been picked up by our screening method suggests that these mutations led to a normal photoautotrophic phenotype. A novel method of intragenic complementation in Synechocystis sp. strain PCC 6803 was developed to facilitate genetic analysis of psbDI mutants containing several amino acid changes in the targeted domain. Recombination between genome copies in the same cell appears to be much more prevalent in Synechocystis sp. strain PCC 6803 than was generally assumed.

Amino Acid Sequence↗

PubMed2001

CRMP-5 neuronal autoantibody: marker of lung cancer and thymoma-related autoimmunity.

We have defined a new paraneoplastic immunoglobulin G (IgG) autoantibody specific for CRMP-5, a previously unknown 62-kd neuronal cytoplasmic protein of the collapsin response-mediator family. CRMP-5 is in adult central and peripheral neurons, including synapses, and in small-cell lung carcinomas. Since 1993, our Clinical Neuroimmunology Laboratory has detected CRMP-5-IgG in 121 patients among approximately 68,000 whose sera were submitted for standardized immunofluorescence screening because a subacute neurological presentation was suspected to be paraneoplastic. This makes CRMP-5 autoantibody as frequent as PCA-1 (anti-Yo) autoantibody, second only to ANNA-1 (anti-Hu). Clinical information, obtained for 116 patients, revealed multifocal neurological signs. Most remarkable were the high frequencies of chorea (11%) and cranial neuropathy (17%, including 10% loss of olfaction/taste, 7% optic neuropathy). Other common signs were peripheral neuropathy (47%), autonomic neuropathy (31%), cerebellar ataxia (26%), subacute dementia (25%), and neuromuscular junction disorders (12%). Spinal fluid was inflammatory in 86%, and CRMP-5-IgG in 37% equaled or significantly exceeded serum titers. Lung carcinoma (mostly limited small-cell) was found in 77% of patients; thymoma was in 6%. Half of those remaining had miscellaneous neoplasms; all but two were smokers. Serum IgG in all cases bound to recombinant CRMP-5 (predominantly N-terminal epitopes), but not to human CRMP-2 or CRMP-3.

Amino Acid Sequence↗

PubMed2001

The principle and technique of using Chinese drugs in the treatment of hypertension.

Differential use of Chinese and western drugs, and combination of traditional theory of materia medica with the results of modern pharmacological research can be regarded as a general principle in the treatment of a disease, while combination of lowering blood pressure with preventing and treating complications is a specific method in the treatment of hypertension. As to the use of drugs based on differentiation of diseases and/or symptoms, drugs which have the action of relieving symptoms but also reducing blood pressure should be used as the first choice. For those drugs which have the action of relieving symptoms but can not lower blood pressure should not be used or should be used as less as possible. Drugs with action of raising blood pressure are contraindicated. When patients have the symptoms of hyperactivity of yang resulting from yin deficiency, Huang Bo ([symbol: see text] Cortex Phellodendri) and Zhi Mu ([symbol: see text] Rhizoma Anemarrhenae) are used together to enhance the effects of both nourishing yin to reduce pathogenic fire, and reducing blood pressure. This practice conforms to the TCM theory and also to the modern pharmacological research.

Diagnosis, Differential↗

PubMed2000

Soluble epoxide hydrolase regulates hydrolysis of vasoactive epoxyeicosatrienoic acids.

The cytochrome P450-derived epoxyeicosatrienoic acids (EETs) have potent effects on renal vascular reactivity and tubular sodium and water transport; however, the role of these eicosanoids in the pathogenesis of hypertension is controversial. The current study examined the hydrolysis of the EETs to the corresponding dihydroxyeicosatrienoic acids (DHETs) as a mechanism for regulation of EET activity and blood pressure. EET hydrolysis was increased 5- to 54-fold in renal cortical S9 fractions from the spontaneously hypertensive rat (SHR) relative to the normotensive Wistar-Kyoto (WKY) rat. This increase was most significant for the 14,15-EET regioisomer, and there was a clear preference for hydrolysis of 14, 15-EET over the 8,9- and 11,12-EETs. Increased EET hydrolysis was consistent with increased expression of soluble epoxide hydrolase (sEH) in the SHR renal microsomes and cytosol relative to the WKY samples. The urinary excretion of 14,15-DHET was 2.6-fold higher in the SHR than in the WKY rat, confirming increased EET hydrolysis in the SHR in vivo. Blood pressure was decreased 22+/-4 mm Hg (P:<0.01) 6 hours after treatment of SHRs with the selective sEH inhibitor N:, N:'-dicyclohexylurea; this treatment had no effect on blood pressure in the WKY rat. These studies identify sEH as a novel therapeutic target for control of blood pressure. The identification of a potent and selective inhibitor of EET hydrolysis will be invaluable in separating the vascular effects of the EET and DHET eicosanoids.

8,11,14-Eicosatrienoic Acid↗

PubMed2000

Binding interactions of vancomycin tracers with a bacterial cell wall peptidoglycan analogue.

Binding interactions between several vancomycin tracers and (N,N'-diacetyl)KDADA in solution were evaluated in a competition format using a surface plasmon resonance instrument. Tracers derivatized from the carboxy terminus or the N-vancosaminyl sugar moiety of vancomycin bind the peptide with an affinity similar to that of underivatized vancomycin. In contrast, N-methylleucyl derivatized vancomycin tracers bind the peptide with a reduced affinity relative to vancomycin.

Anti-Bacterial Agents↗

PubMed2000

Transposon diversity in Arabidopsis thaliana.

Recent availability of extensive genome sequence information offers new opportunities to analyze genome organization, including transposon diversity and accumulation, at a level of resolution that was previously unattainable. In this report, we used sequence similarity search and analysis protocols to perform a fine-scale analysis of a large sample ( approximately 17.2 Mb) of the Arabidopsis thaliana (Columbia) genome for transposons. Consistent with previous studies, we report that the A. thaliana genome harbors diverse representatives of most known superfamilies of transposons. However, our survey reveals a higher density of transposons of which over one-fourth could be classified into a single novel transposon family designated as Basho, which appears unrelated to any previously known superfamily. We have also identified putative transposase-coding ORFs for miniature inverted-repeat transposable elements (MITEs), providing clues into the mechanism of mobility and origins of the most abundant transposons associated with plant genes. In addition, we provide evidence that most mined transposons have a clear distribution preference for A + T-rich sequences and show that structural variation for many mined transposons is partly due to interelement recombination. Taken together, these findings further underscore the complexity of transposons within the compact genome of A. thaliana.

Amino Acid Sequence↗

PubMed2000

Human G protein gamma(11) and gamma(14) subtypes define a new functional subclass.

The mammalian gamma subunit family consists of a minimum of 12 members. Analysis of the amino acid sequence conservation suggests that the gamma subunit family can be divided into three distinct subclasses. The division of the gamma subunit family into these classes is based not only on amino acid homology, but also to some extent on functional similarities. In the present study, two new members of the gamma subunit family, the gamma(11) and gamma(14) subunits, are identified and characterized in terms of their expression and function. The gamma(11) and gamma(14) subunits are most closely related to the gamma(1) subunit and share similar biochemical properties, suggesting their inclusion in class I. However, despite their close phylogenetic relationship and similar biochemical properties, the gamma(1), gamma(11), and gamma(14) subunits exhibit very distinct expression patterns, suggesting that class I should be further subdivided and that the signaling functions of each subgroup are distinct. In this regard, the gamma(11) and gamma(14) subunits represent a new subgroup of farnesylated gamma subunits that are expressed outside the retina and have functions other than phototransduction.

Amino Acid Sequence↗