Biomedical subjects

D Ren

Publications and source records attributed to D Ren.

At least 37 records · Page 2Linked to original sources

PubMed2000

Association between attention deficit hyperactivity disorder and the DXS7 locus.

Attention deficit hyperactivity disorder (ADHD) is a prevalent disorder in children. The etiology of this disease is not clear. Genetics studies have suggested the involvement of the dopamine DRD-4 receptor gene and dopamine transporter gene (DAT1). Clinical studies have shown that monoamine oxidase-B (MAO-B) inhibitors are effective in the treatment of ADHD. These findings suggest that monoamine oxidase (MAO) genes might be involved in the origin of ADHD. In the present work, the DXS7 locus of chromosome X, which is closely linked to MAO genes, was selected as a marker to study the possible association between ADHD and MAO genes in the Chinese population. Haplotype-based haplotype relative risk (HHRR) and the transmission disequilibrium test (TDT) methods were employed to analyze the association and the linkage disequilibrium, respectively. Significant association (X(2) = 15.86; 1 df; P < 0.001) and linkage (X(2) = 14.88; 1 df; P < 0.001) were detected between the 157-bp allele of the DXS7 locus and the DSM-III-R-diagnosed ADHD (N = 72) in trios composed of father, mother, and affected offspring. The data suggested that ADHD was associated and in linkage with DXS7 locus.

Alleles↗

PubMed2000

The complete unique long sequence and the overall genomic organization of the GA strain of Marek's disease virus.

We have determined the DNA sequence of the unique long (UL) region and the repeat long (RL) region in the genome of serotype 1 GA strain of Marek's disease virus (MDV), a member of the alpha-herpesvirus family. With this information, the complete nucleotide sequence of GA-MDV is now known. The entire GA-MDV genome is predicted to be about 174 kbp in size, with an organization of TRL-UL-IRL-IRS-US-TRS, typical of a alpha-herpesvirus. The UL sequence contains 113,508 bp and has a base composition of 41.7% G + C. A total of 67 ORFs were identified completely within the UL region, among which 55 are homologous to genes encoded by herpes simplex virus-1. Twelve of them are unique with presently unknown functions. The sequence of RL reported here together with those published earlier reveal the major structural features of the RL. Virtually all of the ORFs encoded by RL are specific to serotype I of MDV. These ORFs are likely to contribute to some of the unique biological properties of MDV. Among the proteins encoded by MDV-specific ORFs are Meq, a jun/fos family of transcriptional factor implicated in transformation and latency, virus-encoded interleukin-8, a CXC chemokine, and pp38 and pp24, two phosphoproteins with undefined functions. There is also a putative lipase gene (LORF2) that has homologies in HPRS-24 (serotype II) strain of MDV and in various avian adenoviruses. An additional unique feature of MDV is the presence of long terminal repeat remnant sequences of avian retrovirus reticuloendotheliosis virus. These remnant sequences are derived from the U3-enhancer region through ancestral insertions by reticuloendotheliosis virus proviruses.

DNA Replication↗

PubMed2000

Dissociation of the peptide bond in protonated peptides.

The dissociation of the amide (peptide) bond in protonated peptides, [M + H](+), is discussed in terms of the structures and energetics of the resulting N-terminal b(n) and C-terminal y(n) sequence ions. The combined data provide strong evidence that dissociation proceeds with no reverse barriers through interconverting proton-bound complexes between the segments emerging upon cleavage of the protonated peptide bond. These complexes contain the C-terminal part as a smaller linear peptide (amino acid if one residue) and the N-terminal part either as an oxazolone or a cyclic peptide (cyclic amide if one residue). Owing to the higher thermodynamic stability but substantially lower gas-phase basicity of cyclic peptides vs isomeric oxazolones, the N-terminus is cleaved as a protonated oxazolone when ionic (b(n) series) but as a cyclic peptide when neutral (accompanying the C-terminal y(n) series). It is demonstrated that free energy correlations can be used to derive thermochemical data about sequence ions. In this context, the dependence of the logarithm of the abundance ratio log[y(1)/b(2)], from protonated GGX (G, glycine; X, varying amino acid) on the gas-phase basicity of X is used to obtain a first experimental estimate of the gas-phase basicity of the simplest b-type oxazolone, viz. 2-aminomethyl-5-oxazolone (b(2) ion with two glycyl residues).

Journal Article↗

PubMed2000

Association analysis of variants in the core promoter region of angiotensinogen gene with essential hypertension in Tibetan population.

OBJECTIVE: To detect the variants in the core promoter region of angiotensinogen(AGT) gene, and to analyse the relationship between the AGT gene polymorphisms and essential hypertension in Tibetan population. METHODS: This is a case-control study consisting of 103 essential hypertensive subjects and 82 normotensive controls matched by age and sex. The variants in the AGT gene core promoter region were screened by polymerase chain reaction/single strand conformation polymorphism(PCR/SSCP) and further identified by automated sequencing. The A(-6)G polymorphism was determined in DNA extracted from leucocytes by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). RESULTS: (1) There were two different electrophoresis band patterns in PCR/SSCP analysis. PCR product direct sequencing showed that the two band patterns represented the AA, AC genotypes in the (-20) site of AGT gene respectively. The distribution of A(-20)C genotype was almost identical in essential hypertensive and normotensive groups (P>0.8). The A allele frequency was very high in both groups (control: 0.9175, hypertensive: 0.9124). (2)Distribution of genotype in the (-6) site of AGT gene was much different between the patient group and control group (P<0.005). The frequency of G allele was statistically higher in the patient group than in controls (0.374 vs 0.220, P<0.025). CONCLUSION: Both Tibetan hypertensives and normotensives have higher frequency of A allele in AGT gene (-20) site. The higher frequency of G allele in the AGT gene (-6) site in Tibetan hypertension patients suggests that this allele may be the genetic susceptibility factor in the proceeding of essential hypertension in the Tibetan population.

Angiotensinogen↗

PubMed2000

Effects of intestinal endotoxemia on pathogenesis of liver injury induced by thioacetamide.

OBJECTIVE: To study the effect of intestinal endotoxemia on pathogenesis of liver injury induced by thioacetamide (TAA). METHODS: Twenty-six male Wistar rats were divided into 4 groups, namely: normally control group (N), colectomy control group (C), colectomy+TAA group (C+T), TAA group (T). The changes in plasma biochemistry were measured. RESULTS: Plasma endotoxin levels were significantly higher in TAA group than normally control group. Plasma endotoxin levels in colectomy+TAA group were close to that of normally control group. Plasma ALT activity in colectomy+TAA group increased significantly compared with that of normal control group, but markedly lower than that in TAA group. Plasma endotoxin levels were positively correlated to ALT activity in T and C+T groups (r=0. 985, P<0.01). CONCLUSION: TAA itself has a deleterious effect to hepatic cells. It can also induce intestinal endotoxemia in which the liver injury is more inclined to occur and severe.

Alanine Transaminase↗

PubMed2000

DNA analysis of a pedigree with myotonic dystrophy in Songjiang county, Shanghai.

OBJECTIVE: To make the molecular analysis of a pedigree with myotonic dystrophy (DM) in Songjiang county, Shanghai, and to observe the connection between CTG repeat number and clinical features. METHODS: In twenty-three individuals of a pedigree with DM, CTG trinucleotide repeat numbers located in the 3' untranslated region of a protein kinase gene (MTPK) on chromosome 19q13.2-3 were analyzed by using Long Expand TM Template PCR system. RESULTS: Four of eight clinical patients had expanded DM allele, the other four had no expanded CTG copies. Seven of eight suspicious DM cases had expanded CTG repeat numbers and were therefore genetically diagnosed as DM, and an asymptomatic individual was diagnosed as a doubted DM patient by DNA analysis. High risk of DM in six of seven individuals was ruled out, and a clinical doubted DM individual was ascertained a normal person by molecular analysis. A positive correlation was found beween early onset and expanded CTG repeat number in six parents (or grandparents)/child pairs, but in the pair II 2 /IV 7 CTG repeat numbers were reduced from 3100 in the grandmother to 175 in her grandson and there was no anticipation phenomenon. CONCLUSION: The measurement of CTG repeat number can help to ascertain the diagnosis of DM in clinical and preclinical patients, but some clinically- diagnosed DM patients might have normal CTG repeat numbers. Anticipation phenomena were common in the pedigree.

Adolescent↗

PubMed2000

[Analyses on the association of CA-repeat polymorphism and A1166-->C variant in the 3'-flanking region of AT(1)R gene with essential hypertension in Tibetans].

OBJECTIVE: To investigate whether CA-repeat polymorphism and A1166 --> C variant in the 3n-flanking region of AT(1)R gene are in association with the genetic susceptibily to essential hypertension (EH) in Tibetans. METHODS: A case-control study was carried out. Sibpair analysis and family linkage analysis were conducted. The CA-repeat polymorphism of AT &(1) R gene was identified by polymerase chain reaction(PCR) with fluorescence labeled dCTP as substrate and by semi-automatic sequence technology. The A1166 -->C variant was detected by PCR-RFLP. RESULTS: Association of AT&(1)R gene locus with EH was confirmed through the case-control study in well-characterized group of 113 Tibetan EH patients and 131 normotensives(chi(2)=26.44, P<0.001). A closer examination of this gene locus found 11 alleles from Tibetan population; allele A7 (138 bp) was more frequent in both the patients and the controls. Allele A8(140 bp) was in strong positive association with genetic susceptibility to EH in Tibetans. Frequency of allele A8 was 20.5% in EH and 7.3% in normotensives. The difference of allele frequencies between the groups was significant (chi(2)=9.64, P=0.002, OR=3.46, 95% CI 1.44-8.51). Affected sibpair analysis showed chi(2)=3.85, P=0.025; family linkage analysis gave Lod score of 0.80. No association between A1166 --> C variant in AT(1)R gene and EH in Tibetans was observed (P>0.05). CONCLUSION: The result suggests that CA-repeat polymorphism of AT(1)R gene be in association with EH in Tibetans, which implicates that AT(1)R gene may be in linkage disequilibrium with the causative genes of EH.

Adult↗

PubMed2000

[Immune responses of a recombined live Salmonella typhimurium SL3261 expressing a multi-epitope antigen of HCV].

A multi-epitope antigen gene of hepatitis C virus(HCV) was fused to beta-galactosidase gene and introduced into attenuated Salmonella typhimurium SL3261 to construct HCV recombined live vaccine candidate SL3261 (pWR/PCX). when the oral live bacteria were used to immunize mice or rabbits, specific anti-GZ-PCX IgG was detected at week 6 and the strongest antibody responses happened at week 12 at a titer of 1:800 and 1:25,600 in mice and rabbits, respectively, which showed significant difference compared with those of SL3261 and blank controls. Anti-GZ-PCX sIgA in mice's intestine and anti-LPS antibody in sera were also detected. The oral live bacteria elicited obvious DTH reaction and proliferation response of peripheral lymphocytes by GZ-PCX antigen. The body weight of immunized mice slightly decreased but no other toxic effects was observed, which showed the safety of oral immunization. The study of oral live HCV multi-epitope vaccine might be able to provide a new route for the researches of HCV vaccines.

Animals↗

PubMed1999

Magnetite Nanoparticles Prepared by Precipitation from Partially Reduced Ferric Chloride Aqueous Solutions.

Spherical magnetite particles with mean diameter of about 10 nm or less were prepared by means of a reduction-precipitation method with ferric chloride as starting material, which was partially reduced to ferrous salts by Na2SO3 before alkalinizing with ammonia. It was found that the nature of the product depends strongly on the initial ratio R0 = [Fe3+]0/[SO2-3]0. The most appropriate ratio was 3 as proved by X-ray diffraction analysis on the samples although the initial concentration of ferric chloride can be different. Particle diameter increased from ca. 3 to ca. 11 nm with an increase of the concentration of aqueous ferric chloride from 0.075 to 0.45 mol dm-3. The advantage of this method lies in the formation of a red intermediate during the reduction process, which enables us to prevent the reoxidation of the ferrous ions by adding precipitation agents at the end of the reduction reaction without the protection of nitrogen or argon. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Preparation and Characterization of Nanoscopic Organic Semiconductor of Oxovanadium Phthalocyanine.

Nanoscopic particles of oxovanadium phthalocyanine (VOPc, phase-II) with different particle sizes are prepared by aggregation of VOPc molecules in the presence of surfactants for the first time. A size effect in the region of nanoscale was observed in the UV-visible spectra. The photoconductivity of the nanoscopic VOPc is much higher than that of bulk VOPc. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

No association between the intronic presenilin 1 polymorphism and Alzheimer's disease in the Chinese population.

Wragg et al. [1996: Lancet 347:509-512] recorded an association between the intron-based presenilin 1 (PS1) genotype 1/1 and late-onset Alzheimer's disease (AD). This study was performed to determine if there is a similar association in the Chinese population. Ninety-one AD cases, 50 multiinfarct dementia (MID) patients, and 73 age-matched normal controls were recruited. Genotyping of PS1 and apolipoprotein E (APOE) was performed by the methods of polymerase chain reaction and restriction fragment length polymorphism. In AD, MID, and normal controls PS1 allele 1 frequency was 0.6703, 0.5600, and 0.6301, respectively; PS1 allele 2 frequency was 0.3297, 0.4400, and 0.3699, respectively. No association was detected between these diseases and any PS1 allele or genotype. There was only a nearly significant negative association between MID and PS1 genotype 1/1 in the subgroup population bearing APOE allele E4 (odds ratio = 0.2753, P = 0.0776). Our results do not support the conclusion that the intronic PS1 polymorphism is associated with Alzheimer's disease.

Aged↗

PubMed1999

Molecular Orientation of Hydroquinone Adsorbed at a Platinum(111) Thin-Layer Electrode.

Reported are new findings regarding the molecular orientation of hydroquinone (HQ) adsorbed on Pt surfaces. The packing density of hydroquinone adsorbed from 1 M HClO4 supporting electrolyte has been measured by use of a Pt(111) thin-layer electrode. The packing-density-vs-concentration profiles for hydroquinone, measured by a differential thin-layer electrode method at an ordered Pt(111) surface and at an electrochemically disordered Pt(111) surface, are identical within an experimental error of about 8%. The profiles from this study are similar to the ones obtained previously at an ordered Pt(111) surface by Auger spectroscopy, but they are significantly different from those reported previously for polycrystalline Pt thin-layer electrodes. A procedure based upon displacement of HQ by thiocyanate has been developed as an alternative method for determining the packing density of adsorbed HQ. Both methods afford information regarding the molecular state of HQ adsorbed at the Pt(111) surface. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Tumor necrosis factor expression in arterial walls of diabetic rats.

Immunohistochemistry was used to detect tumor necrosis factor (TNF-alpha) expression in arterial wall of diabetic rats. It was found that endothelial cells were swollen and markedly proliferative in these vessels and accordingly TNF-alpha showed strong positive immunohistochemical reaction in endothelial cells or extracellular intimal matrix of such vessels, which might be caused by the expression and release of TNF-alpha from monocytes and arterial wall cells stimulated by AGEs. These findings suggested that increased TNF-alpha expression might be associated with vascular damage and remodeling in diabetes.

Animals↗

PubMed1999

A region within the RAP74 subunit of human transcription factor IIF is critical for initiation but dispensable for complex assembly.

Human transcription factor IIF (TFIIF) is an alpha(2)beta(2) heterotetramer of RNA polymerase II-associating 74 (RAP74) and RAP30 subunits. Mutagenic analysis shows that the N-terminal region of RAP74 between L155 (leucine at codon 155) and M177 is important for initiation. Mutants in this region have reduced activity in transcription, but none are inactive. Single amino acid substitutions at hydrophobic residues L155, W164, I176, and M177 have similar activity to RAP74(1-158), from which all but three amino acids of this region are deleted. Residual activity can be explained because each of these mutants forms a complex with RAP30 and recruits RNA polymerase II into the preinitiation complex. Mutants are defective for formation of the first phosphodiester bond from the adenovirus major late promoter but do not appear to have an additional significant defect in promoter escape. Negative DNA supercoiling partially compensates for the defects of TFIIF mutants in initiation, indicating that TFIIF may help to untwist the DNA helix for initiation.

Adenoviridae↗

PubMed1999

The RAP74 subunit of human transcription factor IIF has similar roles in initiation and elongation.

Transcription factor IIF (TFIIF) is a protein allosteric effector for RNA polymerase II during the initiation and elongation phases of the transcription cycle. In initiation, TFIIF induces promoter DNA to wrap almost a full turn around RNA polymerase II in a complex that includes the general transcription factors TATA-binding protein, TFIIB, and TFIIE. During elongation, TFIIF also supports a more active conformation of RNA polymerase II. This conformational model for elongation is supported by three lines of experimental evidence. First, a region within the RNA polymerase II-associating protein 74 (RAP74) subunit of TFIIF (amino acids T154 to M177), a region that is critical for isomerization of the preinitiation complex, is also critical for elongation stimulation. Amino acid substitutions within this region are shown to have very similar effects on initiation and elongation, and mutagenic analysis indicates that L155, W164, N172, I176, and M177 are the most important residues in this region for transcription. Second, TFIIF is shown to have a higher affinity for rapidly elongating RNA polymerase II than for the stalled elongation complex, indicating that RNA polymerase II alternates between active and inactive states during elongation and that TFIIF stimulates elongation by supporting the active conformational state of RNA polymerase II. The deleterious I176A substitution in the critical region of RAP74 decreases the affinity of TFIIF for the active form of the elongation complex. Third, TFIIF is shown by Arrhenius analysis to stimulate elongation by populating an activated state of RNA polymerase II.

Amino Acid Sequence↗

PubMed1999

[Portal hypertensive vasculopathy of splenic artery].

OBJECTIVE: To study the pathological changes of splenic artery wall in portal hypertensive patients. METHODS: The pathological changes and iNOS activity of splenic artery wall were studied in 21 patients with liver cirrhosis and 15 normal subjects, using light and electron microscope and immunohistochemistry. RESULTS: Compared with normal individuals, the splenic artery of cirrhotic patients showed that the intima was thickened, split and broken, and the smooth muscle layer of middle membrane was thicker and migrated to underintima space. In cirrhotic patients, regression, atrophy or hypertrophy and hyperplasia were seen in smooth muscle cells whose contractile phenotype changed to synthetic phenotype as well. iNOS activated obviously. Extracellular matrix increased in the wall, resulting in collagenic and fibrous changes. CONCLUSIONS: Hemodynamic alteration due to liver cirrhosis induced pathological changes of splenic artery, including the damage to contractile structure and increase of iNOS activity. It is one of the reasons of decrease of artery reaction to contractile vasoactive materials.

Adult↗

PubMed1999

[Preventive effect of vitamin K1 and calcium on osteoporosis in ovariectomized rat].

Ovariectomized female Wistar rats[(170 +/- 15) g] were treated with vitamin K1 or/and calcium for 6 months, in order to study the effect of vitamin K or/and calcium supplementation on the prevention of osteoporosis. Vitamin K1(90 mg/kg) or/and calcium(5 g/kg) were added to a semisynthetic basal diet (VK 50 micrograms/kg, Ca5 g/kg). The findings of the study were as follows: Vitamin K1 treatment led to a significant increase of bone mineral density of the femoral diaphysis and lumbar spine, and bone ash content of the proximal one third of the femur shaft. The results suggested that vitamin K1 could, to some extent, prevent the fast bone loss and the femoral fragility induced by ovariectomy. Regarding the parameters of bone metrology and biomechanics, the effect of vitamin K1 combined with calcium on the prevention of osteoporosis is better than that of vitamin K1 or calcium alone, and the treatments with VK and Ca had better effects on femur than lumbar spine. The present study indicates that for postmenopausal women, as a risk population of osteoporosis, to increase their dietary intake of vitamin K and calcium might be helpful.

Animals↗

PubMed1999

[Expression of a HCV multi-epitopes antigen gene and study on its immunogenicity].

Due to the hypervariable character of hepatitis C virus (HCV), 5 conserved T and/or B cell epitopes from core, envelope, NS3 and NS5 protein of HCV were chosen to form a 270 bp multi-epitopes antigen gene. The gene was clone into a fusion vector pWR450-1 to express a beta-galactosidase-HCV hybrid protein GZ-PCX. The purified GZ-PCX protein was specifically recognized by human anti-HCV antibodies. These results show that the HCV hybrid multi-epitopes antigen has excellent immunogenicity, which might be able to be used as an effective diagnosis agent and to provide protectivity to any genotype of HCV which might partly solve the problems in the researches of HCV vaccines.

Epitopes↗