Biomedical subjects

Q Su

Publications and source records attributed to Q Su.

At least 19 recordsLinked to original sources

PubMed2001

Effect of precursor protein phosphorylation on import into isolated chloroplasts from Chlamydomonas.

In higher plants, chloroplast-destined precursor proteins are thought to be phosphorylated. Mediated by a specific 14-3-3 protein, these phosphorylated proteins bind to the chloroplast surface and are subsequently imported into the chloroplast. We demonstrate that also in the green alga Chlamydomonas reinhardtii the precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase becomes phosphorylated by a plant protein kinase and that the phosphorylation site is located in the transit peptide. The phosphorylation status of the precursor protein regulates its import into chloroplasts especially at an early step during this process. The possible physiological function is discussed.

Animals↗

PubMed2001

SNAP-29: a general SNARE protein that inhibits SNARE disassembly and is implicated in synaptic transmission.

Using the yeast two-hybrid system with syntaxin-1A as bait, we isolated soluble NSF attachment protein (SNAP)-29 from a human brain cDNA library. Synaptosomal fractionation and immunocytochemical staining of hippocampal neurons in culture showed that SNAP-29 is present at synapses and is predominantly associated with synaptic vesicles. The interaction of SNAP-29 with syntaxin-1 was further confirmed with immunoprecipitation analysis. Binding competition studies with SNAP-29 demonstrated that it could compete with alpha-SNAP for binding to synaptic SNAP receptors (SNAREs) and consequently inhibit disassembly of the SNARE complex. Introduction of SNAP-29 into presynaptic superior cervical ganglion neurons in culture significantly inhibited synaptic transmission in an activity-dependent manner. Although SNAP-29 has been suggested to be a general SNARE component in membrane trafficking, our findings suggest that it may function as a regulator of SNARE complex disassembly and modulate the process of postfusion recycling of the SNARE components.

Animals↗

PubMed2001

Comparison of simultaneous distillation extraction and solid-phase microextraction for the determination of volatile flavor components.

Traditional simultaneous distillation extraction (SDE) and solid-phase microextraction (SPME) techniques were compared for their effectiveness in the extraction of volatile flavor compounds from various mustard paste samples. Each method was used to evaluate the responses of some analytes from real samples and calibration standards in order to provide sensitivity comparisons between the two techniques. Experimental results showed traditional SDE lacked the sensitivity needed to evaluate certain flavor volatiles, such as 1,2-propanediol. Dramatic improvements in the extraction ability of the SPME fibers over the traditional SDE method were noted. Different SPME fibers were investigated to determine the selectivity of the various fibers to the different flavor compounds present in the mustard paste samples. Parameters that might affect the SPME, such as the duration of absorption and desorption, temperature of extraction, and the polarity and structure of the fiber were investigated. Of the various fibers investigated, the PDMS-DVB fiber proved to be the most desirable for these analytes.

Chromatography, Liquid↗

PubMed2001

A study on the detection of weak photoacoustic signals by stochastic resonance.

On the basis of stochastic resonance (SR) theory a study of the detection of photoacoustic (PA) signals without a lock-in amplifier is presented. The applicability of the SR method is investigated both with simulated signals calculated by use of a Gaussian model and with experimental PA signals. Signal-to-noise ratio (SNR) is improved substantially by adjusting the properties of a non-linear system to realize SR. By use of this method the lock-in amplifier can be removed from a PA spectrometer.

Journal Article↗

PubMed2001

Rapid method for the isolation of full length adenoviral genomes by bacterial intermolecular homologous recombination.

Recombinant adenoviruses are used widely in gene therapy research. Much work has been carried out to remove specific components of the wild type adenovirus (e.g. E1 gene) in order to make them safer for human use. In addition to such efforts, it is vitally important to ensure that the production of recombinant adenoviruses meet safety guidelines not only with regard to the absence of replication competent adenoviruses but for other variant species that may be present in a viral preparation. In this report, a time and cost efficient method is described for the isolation of full length adenovirus genomes without resorting to plaque purification. The procedure uses a bacterial homologous recombination system and results in the conversion of the double-stranded linear adenovirus genome into a circularized plasmid form that can be easily analyzed by restriction digestion, PCR, DNA sequencing or used in transient transfection studies. Also, the adenovirus plasmids that are generated may also be rescued back into virus form if needed. The entire procedure takes 4 days or less instead of weeks that plaque purification or dilution cloning requires. Furthermore, the method does not require the use of tissue culture materials or facilities. More importantly, this procedure allows for a more extensive and thorough examination of any viral preparation, since it allows for the detection of variants incapable of propagation without the assistance of co-infecting intact adenoviral genomes. Under standard conditions of plaque purification, these variant genomes are not detected. It is predicted that far more variant genomes will be observed using this rapid method than would otherwise be detected by standard plaque purification methods.

Adenoviridae↗

PubMed2001

POR C of Arabidopsis thaliana: a third light- and NADPH-dependent protochlorophyllide oxidoreductase that is differentially regulated by light.

During the sequencing of the genome of Arabidopsis thaliana a gene has been identified that encodes a novel NADPH-protochlorophyllide oxidoreductase (POR)-like protein (accession number AC 002560). This protein has been named POR C. We have expressed the POR C protein in Escherichia coli and have determined its in vitro activity. POR C shows the characteristics of a light-dependent and NADPH-requiring POR similar to POR A and POR B. The expression of the POR C gene differs markedly from that of the POR A and POR B genes. In contrast to the POR A and POR B mRNAs, the POR C mRNA has been shown previously to accumulate only after the beginning of illumination. In light-adapted mature plants only POR B and POR C mRNAs were detectable. The amounts of both mRNAs show pronounced diurnal rhythmic fluctuations. While the oscillations of POR B mRNA are under the control of the circadian clock, those of POR C mRNA are not. Another difference between POR B and POR C was found in seedlings that were grown under continuous white light. The concentration of POR C mRNA rapidly declined and soon dropped beyond the limit of detection, after these seedlings were transferred to the dark. On the other hand. POR B mRNA was unaffected by this light/dark shift. When seedlings were exposed to different light intensities, the amounts of POR B mRNA remained the same, while POR A and POR C mRNAs were modulated in an inverse way by these light intensity changes. POR A mRNA was still detectable in seedlings grown under low light intensities but disappeared at higher light intensities, while the mRNA concentration of POR C rose with increasing light intensities. These different responses to light suggest that the functions of the three PORs of Arabidopsis are not completely redundant, but may allow the plant to adapt its needs for chlorophyll biosynthesis more selectively by using preferentially one of the three enzymes under a given light regime.

Adaptation, Physiological↗

PubMed2001

Varying competence for protein import into chloroplasts during the cell cycle in Chlamydomonas.

By studying the import of radioactively labelled small subunit of ribulose-1,5-bisphosphate carboxylase (pSS) into chloroplasts of the green alga C. reinhardtii cw-15 protein delivery to chloroplasts was found to vary during the cell cycle. Chloroplasts were isolated from highly synchronous cultures at different time points during the cell cycle. When pSS was imported into 'young' chloroplasts isolated early in the light period about three times less pSS was processed to small subunit SS than in 'mature' chloroplasts from the middle of the light period. In 'young' chloroplasts also, less pSS was bound to the envelope surface. During the second half of the light period the import competence of isolated chloroplasts decreased again when based on chlorophyll content or cell volume, but did not change significantly when related to chloroplast number. Measurements of pSS binding to the surface of chloroplasts of different age indicated that the adaptation of protein import competence during the cell cycle is due to a variation of the number of binding sites per chloroplast surface area, rather than to modulation of the binding constant.

Adenosine Triphosphate↗

PubMed2001

Improvements in circulating cholesterol, antioxidants, and homocysteine after dietary intervention in an Australian Aboriginal community.

BACKGROUND: Poor nutrition contributes to high rates of coronary heart disease among Australian Aboriginal populations. Since late 1993, the Aboriginal community described here has operated a healthy lifestyle program aimed at reducing the risk of chronic disease. OBJECTIVE: We evaluated the effectiveness of a community-directed intervention program to reduce coronary heart disease risk through dietary modification. DESIGN: Intervention processes included store management policy changes, health promotion activities, and nutrition education aimed at high-risk individuals. Dietary advice was focused on decreasing saturated fat and sugar intake and increasing fruit and vegetable intake. Evaluation of the program included conducting sequential, cross-sectional risk factor surveys at 2-y intervals; measuring fasting cholesterol, lipid-soluble antioxidants, and homocysteine concentrations; and assessing smoking status. Nutrient intakes were estimated from analysis of food turnover in the single community store. RESULTS: There was a significant reduction in the prevalence of hypercholesterolemia (age-adjusted prevalences were 31%, 21%, and 15% at baseline, 2 y, and 4 y, respectively; P < 0.001). There were significant increases in plasma concentrations of alpha-tocopherol, lutein and zeaxanthin, cryptoxanthin, and beta-carotene across the population. Retinol and lycopene concentrations did not change significantly. Mean plasma homocysteine concentrations decreased by 3 micromol/L. There was no significant change in smoking prevalence between the 2 follow-up surveys. There was an increase in the density of fresh fruit and vegetables and carotenoids in the food supply at the community store. CONCLUSION: This community-directed dietary intervention program reduced the prevalence of coronary heart disease risk factors related to diet.

Adolescent↗

PubMed2001

Hepatitis B virus nucleic acids circulating in the blood: distinct patterns in HBs carriers with hepatocellular carcinoma.

Circulating nucleic acids in serum and plasma are common in a variety of disease conditions. Here, we focus (i) on our approach for the detection of various hepatitis B virus (HBV)-related nucleic acids in liver tissue and in serum, (ii) on the progression of the chronic HBV infection, (iii) on the relation of HBV-specific nucleic acids circulating in the blood of patients with hepatocellular carcinoma, and in general (iv) on the diagnostic potential of circulating HBV nucleic acids.

Amino Acid Sequence↗

PubMed2001

Cholangiocarcinoma with a background of hepatitis B virus-associated cirrhosis.

Recently, hepatitis virus-associated chronic hepatitis or cirrhosis has been suggested to be involved in the pathogenesis of cholangiocarcinoma (CC). A 52-year-old man was diagnosed as CC with a background of hepatitis B virus (HBV)-dependent cirrhosis. A minute hepatic tumor was found during the follow-up, and was diagnosed as CC on percutaneous biopsy. The patient died of hepatic failure and an autopsy revealed the tumor to be a well to moderately differentiated adenocarcinoma. An immunohistological analysis of HBV X gene-encoded protein (HBX) was neither detected in the cancerous nor in the noncancerous tissue. No oncogenic role of the virus was verified in this case.

Bile Duct Neoplasms↗

PubMed2001

Expression, deletion [was deleton] and mutation of p16 gene in human gastric cancer.

AIM: To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis, depth of invasion and lymph node metastases, and to evaluate the deletion and mutation of exon 2 in p16 gene in gastric carcinoma. METHODS: The expression of p16 protein was examined by streptavidin-peroxidase conjugated method (S-P);the deletion and mutation of p16 gene were respectively examined by polymerase chain reaction (PCR) and polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) in gastric carcinoma. RESULTS: Expression of p16 protein was detected in 96.25% (77/80) of the normal gastric mucosa, in 92.00% (45/50) of the dysplastic gastric mucosa and in 47.54% (58/122) of the gastric carcinoma. The positive rate of p16 protein expression in gastric carcinoma was significantly lower than that in normal gastric mucosa and dysplastic gastric mucosa (P < 0.05). The positive rate of p16 protein expression in mucoid carcinoma 10.00% (1/10) was significantly lower than that in poorly differentiated carcinoma 51.22% (21/41), undifferentiated carcinoma 57.69% (15/26) and signet ring cell carcinoma 62.50% (10/16) (P < 0.05). The positive rate of p16 protein in 30 cases paired primary and lymph node metastatic gastric carcinoma: There was 46.67% (14/30) in primary gastric carcinoma, 16.67% (5/30) in lymph node metastatic gastric carcinoma. The positive rate of lymph node metastatic carcinoma was significantly lower than that of primary carcinoma (P < 0.05). There was of p16 gene mutation in exon 2, but 5 cases displayed deletion of p16 gene in exon 2 in the 25 primary gastric carcinomas. CONCLUSIONS: The expression loss of p16 protein related to the gastric carcinogenesis, gastric carcinoma histopathological subtypes and lymph metastasis. The mutation of p16 gene in exon 2 may not be involved in gastric carcinogenesis. But the deletion of p16 gene in exon 2 may be involved in gastric carcinogenesis.

Adult↗

PubMed2001

[Gene diagnosis of facioscapulohumeral muscular dystrophy].

OBJECTIVE: Perform gene diagnosis for Chinese facioscapulohumeral muscular dystrophy(FSHD). METHODS: Digest genome DNA with restriction enzymes EcoR I only and EcoR I associated with Bln I. Use 0.6% agarose gel electrophoresis and Southern blotting hybridization with probe P13E11. RESULTS: For FSHD patients, the sizes of EcoR I + Bln I/P13E11 DNA fragments ranged from 15kb to 33kb. For normal controls, they were over 41kb. Two presymptomatic patients were found. CONCLUSION: It is feasible to perform gene diagnosis and presymptomatic diagnosis for most Chinese FSHD patients by Southern blotting hybridization with probe P13E11, following double digestion of genome DNA with restriction enzymes EcoR I and Bln I.

Adult↗

PubMed2001

Circulating hepatitis B virus nucleic acids in chronic infection : representation of differently polyadenylated viral transcripts during progression to nonreplicative stages.

PURPOSE: Beside the established maturation of hepatitis B virus (HBV) transcripts at a polyadenylation signal downstream of the HBV x protein open reading frame, maturation at an internal polyadenylation signal has been observed in the chronically infected liver. In the present study, it was the aim to identify the respective circulating full-length and truncated transcripts in plasma/serum of carriers. EXPERIMENTAL DESIGN: Nucleic acids extracted from sera were analyzed using established PCR and reverse transcription-PCR procedures targeted to HBV x protein gene regions. Amplification products were cloned and sequenced. RESULTS: Base substitution patterns were determined, which indicated infection stages advanced to different degrees regardless of the transcript type analyzed. HBV full-length RNA (fRNA) showed a high correlation with hepatitis B e antigen and viral DNA, indicative for a replicative infection. In contrast, truncated RNA (trRNA) appeared to be independent of hepatitis B e antigen and showed only a weak association with circulating viral DNA. No correlation was observed between the levels of trRNA and the apparent liver damage as reflected by alanine transaminase levels. An age-dependent representation of fRNA and trRNA was observed: fRNA decreased progressively to low levels, whereas trRNA remained at comparably high values. trRNA and RNA not polyadenylated at either of the two polyadenylation signals were detected even in the absence of any other conventional HBV seromarker, including viral DNA. This was shown for patients with cryptogenic cirrhosis and hepatitis C virus carriers. CONCLUSIONS: The identification of HBV RNA in human serum has a diagnostic potential for apparent and for inapparent infection stages.

Adolescent↗

PubMed2001

[Progress in researches on the molecular genetics of facioscapulohumeral muscular dystrophy].

Facioscapulohumeral muscular dystrophy(FSHD) is an autosomal dominant neuromuscular disorder characterized by progressive weakness of the facial, shoulder and upper arm muscles. The major gene involved has been mapped to chromosome 4q35. There is the evidence for genetic heterogeneity. The FSHD- associated DNA rearrangements are due to deletions of integral copies of the 3.3 kb tandem repeated unit from the subtelomeric region on chromosome 4q35. A valuable molecular diagnostic test for FSHD has been created with the use of p13E-11 probe to detect the EcoR I/Bln I double digestion fragment which is usually smaller in FSHD patient than in normal indivdual. Since the FSHD gene has not been identified yet, the exact molecular pathogenesis of FSHD remains unclear. The hypothesis of position effect variegation has been postulated as the underlying genetic mechanism of FSHD. FRG1 (FSHD region gene 1) from human chromosome 4q35 is identified as a candidate gene for FSHD. A significant correlation between the size of rearrangements associated with FSHD and the clinical phenotype has been found. The various rearrangement fragment size may explain the wide range of clinical severity in FSHD.

Chromosome Mapping↗

PubMed2001

Erythrocyte membrane protein abnormalities in beta-thalassemia of the Li nationality in Hainan.

OBJECTIVE: To determine the composition of abnormal red cell membrane skeleton. METHODS: By sodium dodecyl sulphate polyacrylamide gel electrophoresis of ghostcorpuscles, we quantified the amount of protein by densitometric evaluation. RESULTS: The results showed that in beta-thalassemia, the amount of spectrin, 4.5 protein and globin significantly increased compared with the controls (26.05 +/- 1.46, 21.69 +/- 1.86; 22.87 +/- 5.61, 12.99 +/- 2.33; 15.23 +/- 3.31 and 4.97 +/- 2.73, respectively, P < 0.05). CONCLUSION: These data suggest that the erythrocyte membrane protein composition matched with globin in patients with beta-thalassemia of the racial Li minority are different from the normal control. These factors increase rigidity but decrease deformability of the beta-thalassemic red cell membrane, which may lead to hemolytic anemia.

China↗

PubMed2000

Effect of thyroid hormone deficiency on developmental expression of goalpha gene in the brain of neonatal rats by competitive RT-PCR and in situ hybridization histochemistry.

Goalpha is a guanine nucloetide-binding regulatory protein alpha subunit which is mainly distributed in the central nervous system, but it has not previously been reported how it is regulated by thyroid hormone in the brain of neonatal rat at transcriptional levels. In this report, we used quantitative competitive reverse transcriptional PCR to quantify the effects of TH deficiency on Goalpha gene expression in the brain of neonatal rat at mRNA levels. It was found that Goalpha mRNA levels in the brain of 14-day-old rats significantly increased over 3-fold after induction of perinatal hypothyroidism, and declined markedly after treatment of thyroxine replacement. In situ hybridization histochemistry was further employed to observe the time-course and spatial expression of Goalpha gene in the brain of neonatal rats affected by thyroid hormone deficiency during the developmental period. The data showed that perinatal hypothyroidism can enhance Goalpha mRNA levels in the temporal cortex, sensorimotor cortex, piriform cortex, amygdala, hippocampal CA1-4 subfields, dentate gyrus, arcuate nucleus (AR) and ventromedial hypothalamic nucleus (VMH) of hypothalamus, but not in the striate cortex, cingulate cortex, claustrum, caudate/putamen and thalamus in the brain of rat at 7-21 days post-partum. The results suggest that up-regulation of Goalpha gene expression may be one kind of common mechanism responsible for neurological deficits in some brain areas arising from thyroid hormone deficiency in the critical periods of neonatal rats.

Animals↗

PubMed2000

Relativistic resonances in combined magnetic and laser fields

We propose a mechanism for experimental investigation of relativistic effects in the laser-atom interaction with moderate (nonrelativistic) laser intensities that involves placing the system in a static magnetic field parallel to the laser's magnetic-field component. The resonantly induced relativistic motion of the atomic electron leads to a variety of novel phenomena: a relativistic dephasing leading to a ringlike spatial probability density, a counterintuitive window of relativistically enhanced motion, and a sequence of sawtooth-shaped resonances that may increase the harmonic generation.

Journal Article↗

PubMed2000

A novel method to calculate the approximate derivative photoacoustic spectrum using continuous wavelet transform.

A novel method based on continuous wavelet transform (CWT) using Haar wavelet function for approximate derivative calculation of analytical signals is proposed and successfully used in processing the photoacoustic signal. An approximate nth derivative of an analytical signal can be obtained by applying n times of the wavelet transform to the signal. The results obtained from four other different methods--the conventional numerical differentiation, the Fourier transform method, the Savitzky-Golay method, and the discrete wavelet transform (DWT) method--were compared with the proposed CWT method; it was demonstrated that all the results are almost the same for signals without noise, but the proposed CWT method is superior to the former four methods for noisy signals. The approximate first and second derivative of the photoacoustic spectrum of Pr(Gly)3Cl3.3H2O and PrCl3.6H2O were obtained using the proposed CWT method; the results are satisfactory.

Journal Article↗