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Biomedical subjects

Q Zhang

Publications and source records attributed to Q Zhang.

At least 199 records · Page 11Linked to original sources
PubMed2001

Primary and booster mucosal immune responses to meningococcal group A and C conjugate and polysaccharide vaccines administered to university students in the United Kingdom.

Meningococcal group A+C capsular polysaccharide (PS) conjugate vaccines may prime for serum immunoglobulin G (IgG) memory responses to meningococcal capsular PS. It is not known whether these vaccines induce immunological memory at the mucosal level, which may be important in reducing nasopharyngeal carriage. Mucosal immune responses to meningococcal conjugate and PS vaccines in young adults were investigated. Healthy university students were randomized to receive either a groups A+C meningococcal conjugate vaccine (MACconj, n = 100) or a group A+C meningococcal PS vaccine (MACPS, n = 95). One year after the primary immunization, both groups were randomized again to receive a MACconj or a MACPS booster vaccination. Saliva samples were collected before and 1 month after the primary and booster vaccinations. Anti-meningococcal A (MenA) and C (MenC) PS IgA and IgG antibody levels were measured by a standard enzyme-linked immunosorbent assay. After the primary vaccination, salivary MenA and MenC IgG and MenA IgA concentrations were significantly increased after immunization with both MACconj and MACPS vaccines, but the salivary Men C IgA level was increased only after MACPS vaccine (P < 0.01). IgA responses to both serogroups were greater for MACPS than MACconj vaccine (P < 0.05), whereas no significant differences were seen for IgG responses. MenA IgG titers were higher after the MACPS booster in MACconj-primed subjects than after the MACPS primary vaccination, suggesting the presence of IgG memory. Antibody responses to a dose of either MACPS or MACconj were not significantly reduced in those previously given MACPS compared to the primary responses to those vaccines. Meningococcal A+C conjugate and PS vaccines induce significant mucosal responses in young adults. MACconj priming may induce IgG memory at the mucosal level, which is likely to be a reflection of an anamnestic serum IgG response. No evidence of mucosal hyporesponsiveness was observed after MACPS priming in this study.

Adolescent↗
PubMed2001

Coupled phase-variable expression and epitope masking of selective surface lipoproteins increase surface phenotypic diversity in Mycoplasma hominis.

A new mechanism expanding mycoplasmal surface diversity is described. Exposure of surface epitopes on a constitutively expressed membrane protein (P56) of Mycoplasma hominis was subject to high-frequency phase variation due to phase-variable expression of the P120 antigen and its selective masking of P56 epitopes. Phase-variable masking may confer previously unrealized adaptive capabilities on mycoplasmas.

Antigenic Variation↗
PubMed2001

16S ribosomal DNA sequence analysis distinguishes biotypes of Streptococcus bovis: Streptococcus bovis Biotype II/2 is a separate genospecies and the predominant clinical isolate in adult males.

We characterized 22 human clinical strains of Streptococcus bovis by genotypic (16S rRNA gene sequence analysis [MicroSeq]; Applied Biosystems, Foster City, Calif.) and phenotypic (API 20 Strep and Rapid ID32 Strep systems (bioMerieux Vitek, Hazelton, Mo.) methods. The strains, isolated from blood, cerebrospinal fluid (CSF), and urine, formed two distinct 16S ribosomal DNA sequence clusters. Three strains which were associated with endocarditis urinary tract infection (UTI), and sepsis clustered with the S. bovis type strain ATCC 33317 (cluster 1); other closely related type strains were S. equinus and S. infantarius. Nineteen strains clustered at a distance of about 2.5% dissimilarity to the S. bovis type strain (cluster 2) and were associated with central nervous system (CNS) disease in addition to endocarditis, UTI, and sepsis. All strains were distinct from S. gallolyticus. Within cluster 2, a single strain grouped with ATCC strain 43143 (cluster 2a) and may be phenotypically distinct. All the other strains formed a second subgroup (cluster 2b) that was biochemically similar to S. bovis biotype II/2 (mannitol negative and beta galactosidase, alpha galactosidase, beta glucuronidase, and trehalose positive). The API 20 Strep system identified isolates of cluster 2b as S. bovis biotype II/2, those of cluster 1 as S. bovis biotype II/1, and that of cluster 2a as S. bovis biotype I. There was an excellent correlation of biotype and genotype: S. bovis biotype II/2 isolates form a separate genospecies distinct from the S. bovis, S. gallolyticus, and S. infantarius type strains and are the most common isolates in adult males.

Adult↗
PubMed2001

Nitric oxide and cGMP protein kinase activity in aged ventricular myocytes.

We tested the hypothesis that nitric oxide-induced negative functional effects through cGMP would be reduced in aged cardiac myocytes. Maximum rate of shortening (R(max)) and percent shortening of ventricular myocytes from young (6 mo) and old (3 y) rabbits were studied using a video edge detector. cGMP-dependent phosphorylation was examined by electrophoresis and autoradiography. Myocytes received a nitric oxide donor S-nitroso-N-acetyl-penicillamine (SNAP, 10(-7), 10(-6), and 10(-5) M) followed by KT-5823 (10(-6) M), a cGMP protein kinase inhibitor. Baseline function was similar in young and old myocytes (89.1 +/- 4.5 young vs. 86.4 +/- 8.3 microm/s old R(max), 5.6 +/- 0.3 vs. 5.2 +/- 0.7%shortening). SNAP (10(-5) M) decreased R(max) in both young (25%, n = 6) and old myocytes (24%, n = 7). SNAP also reduced percent shortening by 28% in young and 23% in old myocytes. The negative effects of SNAP were partially reversed by KT-5823 only in young myocytes. Multiple proteins were phosphorylated by cGMP, and KT-5823 could reduce this effect. The degree of phosphorylation was significantly less in old myocytes. These results suggest that the functional response of ventricular myocytes to nitric oxide was preserved during aging. However, the importance of cGMP-dependent protein phosphorylation was decreased, indicating a shift to other pathways.

Aging↗
PubMed2001

Increased frequency of alleles associated with elevated tumor necrosis factor-alpha levels in children with Kawasaki disease.

Genetic polymorphisms influence the magnitude of the cytokine response after an inflammatory stimulus. To determine whether such polymorphisms might play a role in Kawasaki disease (KD), we analyzed white and Japanese children with KD and control populations for two polymorphic loci in which the A allele is associated with high tumor necrosis factor-alpha secretion. The lymphotoxin-alpha+250 A/A genotype was overrepresented among white children with KD compared with controls (0.59 versus 0.36; p = 0.013). The tumor necrosis factor-alpha-308 A/G genotype was overrepresented among whites with KD who had coronary artery abnormalities compared with those with normal echocardiograms (0.36 versus 0.09; p = 0.044). No significant difference was seen at either locus between Japanese children with KD and Japanese controls. The increased frequency of the high secretor alleles in white children with KD suggests that these loci may be related to susceptibility to KD and to outcome after disease.

Alleles↗
PubMed2001

Nesprins: a novel family of spectrin-repeat-containing proteins that localize to the nuclear membrane in multiple tissues.

In search of vascular smooth muscle cell differentiation markers, we identified two genes encoding members of a new family of type II integral membrane proteins. Both are ubiquitously expressed, and tissue-specific alternative mRNA initiation and splicing generate at least two major isoforms of each protein, with the smaller isoforms being truncated at the N-terminus. We have named these proteins nesprin-1 and -2 for nuclear envelope spectrin repeat, as they are characterized by the presence of multiple, clustered spectrin repeats, bipartite nuclear localization sequences and a conserved C-terminal, single transmembrane domain. Transient transfection of EGFP-fusion expression constructs demonstrated their localization to the nuclear membrane with a novel C-terminal, TM-domain-containing sequence essential for perinuclear localization. Using antibodies to nesprin-1, we documented its colocalization with LAP1, emerin and lamins at the nuclear envelope, and immunogold labeling confirmed its presence at the nuclear envelope and in the nucleus where it colocalized with heterochromatin. Nesprin-1 is developmentally regulated in both smooth and skeletal muscle and is re-localized from the nuclear envelope to the nucleus and cytoplasm during C2C12 myoblast differentiation. These data and structural analogies with other proteins suggest that nesprins may function as 'dystrophins of the nucleus' to maintain nuclear organization and structural integrity.

Amino Acid Sequence↗
PubMed2001

In vitro and in vivo study of two types of long-circulating solid lipid nanoparticles containing paclitaxel.

Paclitaxel (Taxol), a diterpenoid isolated from Taxus brevifolia, is effective against several murine tumors, and is one of the most exciting anticancer molecules currently available. Due to its low solubility in water, it is clinically administered with polyethoxylated castor oil (Cremophor EL), which causes serious side effects. Inclusion of paclitaxel in solid lipid nanoparticles (SLNs) has proved to be a good approach to eliminate the need for Cremophor EL and improve the drug's antitumor efficacy. This paper describes the development of two types of long-circulating SLNs as colloidal carriers for paclitaxel. SLNs are constituted mainly of bioacceptable and biodegradable lipids. In vitro release kinetics showed that the release was very slow, the release of paclitaxel from F68-SLN is linear, and the release of paclitaxel from Brij78-SLN followed the Weibull equation. Pharmacokinetics was evaluated in KM mice after injection of paclitaxel formulated in Cremophor EL or in Brij78-SLN and F68-SLN. Encapsulation of paclitaxel in both SLNs produced marked differences compared with the free drug pharmacokinetics. F68-SLN and Brij78-SLN are long-circulating (t 1/2 beta, 10.06 and 4.88 h, respectively) compared with paclitaxel injection (t 1/2 beta, 1.36 h).

Animals↗
PubMed2001

Carbon emissions and sequestration potential of Central African ecosystems.

Joint Implementation under the Climate Change Convention and Clean Development Mechanism of the Kyoto Protocol require a scientific understanding of current carbon stocks, fluxes, and sequestration potential, especially in tropical ecosystems where there are large carbon reservoirs, significant carbon emissions, and large land areas available for reforestation. Central Africa contains 10% of the world's remaining tropical moist forests and has received little attention in carbon studies. In 1980, above-ground carbon stocks in the central African ecosystem were 28.92 Pg and were reduced to 24.79 Pg by 1990. Improved forest management aimed at increasing biomass density could sequester 18.32 Pg of carbon, and over 500,000 km2 formerly forested land will be available by 2050 for reforestation with a capacity to offset 10 Pg carbon. Understanding the spatial distribution of biomass carbon and sequestration potential will be essential for carbon trading initiatives through Joint Implementation and Clean Development Mechanism.

Africa↗
PubMed2001

Characterization of topology-, gestation- and labor-related changes of a cassette of myometrial contraction-associated protein mRNA in the pregnant baboon myometrium.

Our objective was to examine the topology-, gestation- and labor-related changes of estrogen receptor (ER)alpha, progesterone receptor (PR), oxytocin receptor (OTR) and thrombospondin-1 (TSP1) mRNA in pregnant baboon myometrium. ER alpha, PR, OTR and TSP1 mRNAs extracted from the lower uterine segment and fundal myometrium of pregnant baboons not in labor between 121 and 180 days of gestational age (n=9) and in established spontaneous labor between 164 and 193 days of gestational age (n=5) were analyzed by Northern blot. There were no topology-, gestation- or labor-related changes of ER alpha and PR mRNA in or between the lower uterine segment or/and the fundus. OTR mRNA was the same in the lower uterine segment and the fundus from baboons not in labor and non-labor fundal, but not lower uterine segment, myometrial OTR mRNA increased with gestation (R(2)=0.81, P<0.05). Fundal OTR mRNA rose significantly compared with the lower uterine segment during spontaneous labor. TSP1 mRNA increased significantly in both the fundus and lower uterine segment during labor. TSP1 mRNA in the lower uterine segment during spontaneous labor was higher than in the fundus during spontaneous labor. In conclusion, fundal and lower uterine segment ER alpha and PR mRNA remained unchanged in late gestation and spontaneous labor. The increased OTR mRNA may serve as a mechanism to increase uterine sensitivity to OT during late gestation. The higher fundal OTR mRNA compared with the lower uterine segment provides polarity which assists fetal expulsion by uterine contractions during labor. The significance of increased TSP1 mRNA during labor may relate to homeostasis and merits further study.

Animals↗
PubMed2001

Depression and substance use in minority middle-school students.

OBJECTIVES: This study investigated the association between depression and substance use in a sample of middle-school students. METHODS: The 5721 students (59%-63% Hispanic) completed self-report items on depressive symptoms, recent smoking and binge drinking, and lifetime use of marijuana, cocaine, and inhalants. RESULTS: Symptoms of depression were strongly and positively related to substance use. For every type of use, a stepwise increase was seen between the percentage of students with low symptom frequency and the percentage of students with more symptoms. A sizable number of users reported symptoms indicating major depression. Depression scores showed few clinically meaningful differences among demographic subgroups. Substance use scores, in contrast, showed meaningful intergroup differences for racial/ethnic group and other demographic variables. CONCLUSIONS: Depressive symptoms and substance use were associated in a sample of middle-school students who were largely non-White and predominantly Hispanic. Greater understanding of the nature of this association is needed; this understanding should be used to design prevention programs, and prevention programs should be introduced at least in the middle-school years.

Achievement↗
PubMed2001

[Effects of different methods of fetal spinal cord tissue transplanted on reversing the axotomy-induced neurons atrophy rats injured spinal cord].

OBJECTIVE: To explore the effects of different methods of fetal spinal cord(FSC) tissue transplanted on reversing the axotomy-induced neurons atrophy of adult rats injured spinal cord. METHODS: One hundred and twenty adult rats received lumbar spinal cord hemisection. Experimental rats were divided into five groups, the control group(Group A); spinal cord hemisection only(Group B); spinal cord hemisection plus FSC transplant (Group C); spinal cord hemisection plus FSC transplant plus pedicled paraspinal muscle(Group D); spinal cord hemisection plus FSC transplant plus pedicled omentum (Group E). Combined behavioral scores(CBS), somatosensory evoked potentials (SEP), motor evoked potentials(MEP) were examined to evaluate the recovery of neurological function after operation. Rats were sacrificed after 1, 4 and 12 weeks. Nissl stained section was used for neurons quantitative image analysis. The positive cells were quantitative analysis by computer image analysis system. RESULTS: The different methods of FSC tissue transplantation could prevent the neurons atrophy secondary to axon injury of spinal cord in adult rats. The size of neurons were observed in five groups, they were group E > group D > group C > group B > group A (P < 0.05). Those increases in size of neurons were paralleled with a significant improvement in neurological function recovery. CONCLUSION: It indicates that the different methods of FSC tissue transplantation can maintain the neurons morphology and improve the neurological function of rats.

Animals↗
PubMed2001

[Cloning the differentially expressed genes in the retina of rds mouse during the development of retinitis pigmentosa].

OBJECTIVE: To clone the differentially expressed genes in the retina of rds mouse (the animal model of congenital retinitis pigmentosa) during the disease development. METHODS: The retinal mRNA of rds mouse during the development of retinitis pigmentosa was analyzed by the mRNA differential display. The differentially expressed mRNA fragments were cloned and sequenced. RESULTS: There was obvious difference of gene expression between rds mouse and the control during the development of retinitis pigmentosa. Five differentially expressed bands were cloned and sequenced. One of those had 86% identity (132/154) with the sequence of the human cDNA DKFZp434D1227 from adult testis in GenBank, which was submitted lately (15-Oct-1999) and without much information. The other had lower identity with the sequences in GenBank. A highly expressed clone in the rds mouse on postnatal day 25 had the same length as another clone in the normal on postnatal day 37, which was not expressed in the rds mouse on day 37. The sequences of the two clones were identical in all but two base pairs. CONCLUSION: These results indicate that there are a lot of novel differentially expressed genes in the chronic processing diseases, such as retinitis pigmentosa.

Animals↗
PubMed2001

Modulation of 1,3-bis-(2-chloroethyl)-1-nitrosourea resistance in human tumor cells using hammerhead ribozymes designed to degrade O6-methylguanine DNA methyltransferase mRNA.

O6-Methylguanine DNA Methyltransferase (MGMT) protects tumor cells from the cytotoxic effects of the DNA alkylating agent 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU). To improve the therapeutic index of BCNU, biochemical strategies to deplete MGMT activity have been developed. In the present study, a molecular strategy for modulating BCNU resistance was explored using hammerhead ribozymes (Rz) designed to degrade the long-lived MGMT mRNA. The ribozymes were designed against eight GUC sites within the MGMT mRNA. cDNAs of these ribozymes were cloned into an expression vector and then all eight vectors were pooled and stably transfected into HeLa cells. Several HeLa/Rz clones sensitive to a sublethal dose of BCNU were identified using a short-term cell proliferation assay. The ribozyme inserts were amplified from genomic DNA by polymerase chain reaction and sequenced in the BCNU-sensitive clones. The ribozyme inserts Rz161, 178, and 212, targeted against nucleotide 161, 178, and 212, respectively, in the MGMT mRNA, were found to be present in these clones. MGMT activity, Western, and Northern blot analyses revealed that two of the HeLa/Rz clones contained very low levels of MGMT activity, protein, and mRNA. Investigation of CpG methylation within the MGMT promoter indicated that the lack of MGMT expression in these HeLa/Rz clones was not likely due to methylation silencing of the MGMT gene. By colony formation, the cell killing induced by 100 microM BCNU was increased by 2 to 3 logs in the HeLa/Rz clones compared with wild-type HeLa cells.

Antineoplastic Agents, Alkylating↗
PubMed2001

[Detection of numerical chromosome aberrations in sperm of workers exposed to benzene series by two-color fluorescence in situ hybridization].

To study the frequency of numerical chromosome aberrations in sperm of workers exposed to benzene series, the aneuploidy frequencies of 9 and 18 chromosomes were detected in sperm of workers by two color fluorescence in situ hybridization with digoxingenin labeled 9 chromosome probe (D9z1) and biotin labelled 18 chromosome probe (D18z1). The timeweight average air concentration (TWA) of benzene in the workplace was 86.49 mg/m3, it was two fold higher than the national maximum allowable concentration. The concentration of urinary trans, transmuconic acid (ttMA) in exposed group was significantly higher than that of control group. The sperms counted in 14 exposed workers and 16 control workers were 136,401 and 156,955 respectively. The results showed that the disomy frequencies of sperm for chromosome 9 and 18 (0.168% +/- 0.063% and 0.055% +/- 0.031% respectively) and the frequency of diploidy sperm (0.073% +/- 0.045%) were statistically increased over that of the control group (0.050% +/- 0.030%; 0.033% +/- 0.025% and 0.040% +/- 0.036%, respectively). The nullisomic frequencies of 9 and 18 chromosome in the exposed group (0.206% +/- 0.047%, 0.068% +/- 0.044%) were statistically increased over that of the control group too (0.067% +/- 0.037%, 0.048% +/- 0.034%). The frequency of overall numerical chromosome aberrations in the exposed group was 0.570% +/- 0.144%, when this value was compared with that of control (0.218% +/- 0.071%), a statistically significance was presented. Our experiments showed that exposed to benzene at higher concentration may induce increase in aneuploidy frequency of sperm autosomal chromosome in exposed workers.

Benzene↗
PubMed2001

TGF-beta-induced p38 activation is mediated by Rac1-regulated generation of reactive oxygen species in cultured human keratinocytes.

p38 has been shown to be involved in TGF-beta-induced gene expression, but the upstream of the signaling pathway leading to the activation of p38 is left undefined. We investigated the pathway in cultured human keratinocytes (HaCat cells). Western blot analysis revealed that TGF-beta induced the activation of p38 within 1 h post TGF-beta treatment. H2O2 also strongly induced p38 activation in a time dependent manner. We also observed that TGF-beta-induced p38 activation was inhibited by PDTC, pyrrolidinedithiocarbamate, a known antioxidant, and DPI, diphenylene iodonium chloride, one of the known NADPH oxidase inhibitors. In contrast, TGF-beta-induced Smad2 phosphorylation was not affected. To test whether reactive oxygen species (ROS) is involved in TGF-beta-induced p38 activation, we examined the generation of ROS and activation of NADPH oxidase. FACS analysis showed that TGF-beta induced generation of ROS in time-dependent manner. DPI, an inhibitor of NADPH oxidase, inhibited TGF-beta-induced ROS production. Lucigenin-based NADPH oxidase assay indicated that TGF-beta-induced NADPH oxidase activity started as early as 5 min following treatment and peaked at about 15 min with induction of about 2-folds. The activity remained elevated up to 1 h. Immunofluorescence microscopy study showed that Rac1, one of the subunits of NADPH oxidase, translocated from cytoplasm to the membrane within 5 min. Pretreatment with DPI dramatically reduced TGF-beta-induced NADPH oxidase activity. Collectively, our data suggest that TGF-beta-induced p38 activation is mediated by Rac1-regulated generation of reactive oxygen species in cultured human keratinocytes.

Biological Transport↗
PubMed2001

Increased frequency of the tumor necrosis factor-alpha-308 A allele in adults with human immunodeficiency virus dementia.

Genetic polymorphisms in the regulatory regions of various cytokine genes influence the amount of cytokine produced in response to inflammatory stimuli. To determine whether such polymorphisms might play a role in human immunodeficiency virus (HIV) dementia, a disease process in which tumor necrosis factor (TNF)-alpha is believed to play a role, we analyzed HIV-infected adults with and without dementia and control populations for a polymorphic site located in the promoter region of the gene coding for TNF-alpha. The presence of the A allele at the TNF-alpha-308 site was overrepresented among adults with HIV dementia compared to those without dementia (0.28 vs 0.07; OR 5.5; 95% CI 1.8-17.0) and a healthy control population (0.28 vs 0.11). The increased frequency of the A allele in HlV-infected adults with dementia suggests that this locus may play a role in the pathophysiology of dementia and suggests a genetic predisposition for the development of HIV dementia.

AIDS Dementia Complex↗
PubMed2001

Fine mapping of canine XLPRA establishes homology of the human and canine RP3 intervals.

PURPOSE: Canine X-linked progressive retinal atrophy (XLPRA) is a hereditary, progressive retinal degeneration that has been mapped previously to the canine X chromosome in a region flanked by the dystrophin (DMD) and tissue inhibitor of metalloproteinase 1 (TIMP1) genes, and is tightly linked to the gene RPGR. The comparable region of the human X chromosome includes the disease locus for RP3, an X-linked form of retinitis pigmentosa, although the current canine disease interval is much larger. METHODS: To refine the map of the canine XLPRA disease interval, 11 X-linked markers were mapped, both meiotically, in two extensive canine pedigrees informative for XLPRA, and on a 3000-rad canine-hamster radiation hybrid (RH) panel. A 12th marker was mapped on the RH panel alone. RESULTS: The integrated map of this region of CFAX now covers approximately 47.3 centimorgans (cM) and 194 centirays (cR)(3000), and demonstrates strong conservation of synteny between humans and dogs. Genes defining the human RP3 zero-recombination interval (human homologue of mouse t complex [TCTE1L], sushi repeat-containing protein, X chromosome [SRPX], and retinitis pigmentosa guanosine triphosphatase [GTPase] regulator [RPGR]) are tightly linked to each other, to the XLPRA locus, and to the gene ornithine transcarbamylase (OTC) in dogs. CONCLUSIONS: Strong conservation of gene order was demonstrated in the short arm of the X chromosome between dogs and humans as was homology of the canine XLPRA and human RP3 intervals. These results create a valuable tool for investigating canine XLPRA and other X-linked eye diseases in dogs.

Animals↗