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Biomedical subjects

Y Shao

Publications and source records attributed to Y Shao.

At least 73 records · Page 4Linked to original sources
PubMed1999

Emerging HIV infections with distinct subtypes of HIV-1 infection among injection drug users from geographically separate locations in Guangxi Province, China.

Heroin users from Guangxi province, a southern province of China that borders Vietnam in the south and Yunnan province in China in the west, were studied for prevalence and risk factors for HIV-1 infection. Viral env sequences from HIV-1-positive individuals were also determined for subtypes of HIV-1. The overall HIV prevalence among 227 heroin users was 40%. Most had used drugs for < or = 3 years. Sharing of injection equipment and unprotected sex were significantly associated with HIV-1 infection. Subtypes C and E HIV-1 were detected in infected heroin users and were sharply segregated in two geographic locations: only subtype C was found in a border city with Yunnan province, whereas only subtype E was found in a city bordering northern Vietnam. HIV-1 strains within each subtype were remarkably homogenous, with a mean intersubject DNA distance of 2.32% for subtype E and 1.13% for subtype C, respectively. Phylogenetic analysis of C2-V5 region of Guangxi subtype E env sequences revealed significant clustering with subtype E sequences from southern Vietnam and Cambodia. These results suggest that HIV-1 infection among heroin users in Guangxi represents two emerging epidemics initiated from distinct sources: one from Vietnam and another from Yunnan province. Factors associated with HIV-1 infection were not restricted to injection practices. Unprotected sexual behaviors are likely to increase the probability of HIV transmission beyond this high-risk population. Designing and implementing effective intervention strategies targeted toward both injection drug use and high risk sexual behavior are urgently needed to further reduce HIV-1 spread in China.

China↗
PubMed1999

Stereospecific synthesis and biological evaluation of farnesyl diphosphate isomers.

[formula: see text] A unified, stereospecific synthetic route to the three geometric isomers of (E,E)-farnesyl diphosphate (E,E-FPP) (1, 2, and 3) has been developed. The key feature of this synthesis is the ability to control the stereochemistry of triflation of the beta-ketoester 10 to give either 11 or 14. Preliminary evaluation of these compounds with protein-farnesyl transferase indicates that 1 and 2 are surprisingly effective substrates; however, Z,Z-FPP (3) is a poor substrate and a sub-micromolar inhibitor.

Enzyme Inhibitors↗
PubMed1999

[The identification of recombinant HIV-1 strains in IDUs in southwest and northwest China].

OBJECTIVE: To search for possible recombination of HIV-1 strains in China. METHODS: The blood samples were collected from the HIV infected individuals in areas where epidemic of more than two subtypes of HIV-1 were found. The HIV env and tat genes were amplified by nested PCR from PBMCs and directly sequenced and analyzed. RESULTS: The sequence analysis were performed on 14 HIV-1 strains collected in the subtype B' and C epidemic areas of China. No evidence of recombination after sequencing of env was found. The recombnant HIV-1 strains of subtype B' and C were found in 10 of the 14 samples tested when the first exon of the tat gene was sequenced. In addition, three subtype B' and one subtype C non-recombinant HIV-1 strains were found among IDUs in Sichuan Province. CONCLUSIONS: The recombinant HIV-1 strains of subtype B' and C were firstly identified in Sichuan Province of southwest China and Xinjiang Autonomous Region of western China. Their identical sequences and recombinant patterns indicated the same origin of the recombinant strains, it strongly indicates a close correlation between these two HIV epidemic regions. Since no other subtype of HIV-1 except the recombinant was found in Xinjiang, whereas both subtype B and C as well as B'/C recombinant were found in Sichuan, the recombination was most probably happened in Sichuan Province rather than in Xinjiang.

Amino Acid Sequence↗
PubMed1999

[Study on transient infection of T cell lines by M tropic HIV-1 strains].

OBJECTIVE: To reveal the mechanism of transient infection of T cell by HIV-1 isolates of early stages from Yunnan and Xinjiang, China. METHODS: We made these viruses pass on CXCR4 expressing T cell lines and CCR5 expressing U937 cell line. After having observed the biological phenotype, we analyzed sequences of env gene to find genetic mutations of the strains, and used heteroduplex mobility assay (HMA) to show the complexity of the virus groups. RESULTS: Sequence analysis indicated that these viruses are M tropic, NSI strains, correlating with their phenotype; they mutated largely through T cell passage, all showed sequence characteristics deviating from M tropic/NSI to different extents. HMA results indicated the complexity of virus groups was low at the very beginning of the passage and kept high later. CONCLUSION: We concluded that these viruses tried mutating to different directions to adapt the T cell line but all failed. Although env gene correlates with cell tropism, coreceptor usage and HIV syncytium inducing, it may have relationship with the whole genome, whether these phenotypes are present or not. The results imply that there is no T tropic/SI strain in the M topic/NSI virus pool in early infection, it is generated later following continued infection in vivo.

Amino Acid Sequence↗
PubMed1999

Correlates of protection, antigen delivery and molecular epidemiology: basics for designing an HIV vaccine.

Major obstacles in the development of HIV vaccines are the high variability of the virus and its complex interaction with the immune system. Recent studies demonstrated, that CTLs recognizing highly conserved epitopes in the group-specific antigen are capable of controlling HIV-replication in long-term nonprogressors. Necessary consequences for novel vaccine concepts are the presentation of a large repertoire of antigenic sites as well as the stimulation of different effectors of the immune system. Accordingly, different types of recombinant HIV-1 virus-like particles (VLPs) have been constructed stimulating the induction of neutralizing antibodies and HIV-specific CD8-positive CTL responses in preclinical studies. With respect to future vaccine trials, HIV vaccine formulations may need to be tailored to the local strains circulating within a geographical region. The expert group of the joint United Nations Programme on AIDS recently identified Yunnan, a southwestern province of China, as a region, in which the HIV epidemic is starting to gain speed, resembling to the situation in Thailand 10 years ago. A molecular clone of a representative virus strain is now available for the development of innovative antigen delivery systems aiming to be evaluated in future clinical vaccine trials throughout this area.

AIDS Vaccines↗
PubMed1999

Contemporaneous positron emission tomography and MR imaging at 1.5 T.

Simultaneous acquisition of positron emission tomography (PET) and magnetic resonance (MR) images using an MR-compatible PET system will obviate the need for image registration and will allow unique studies of structure and function of living organisms in one setting. Here we report on simultaneous acquisition of PET and MR images on a clinical 1.5 T system using a 54 mm diameter prototype MR-compatible PET system (McPET). Phantom experiments were performed in order to determine the effect of the McPET system on MR images. The results demonstrated the system to be fully MR compatible, in both its detector head construction and operation. The McPET construction offers a promising method for design of a large-scale MR-compatible PET system that will be useful in functional studies of the brain.

Artifacts↗
PubMed1999

Antioxidative phenolic glycosides from sage (Salvia officinalis).

An investigation of Salvia officinalis L. has led to the isolation of three new phenolic glycosides, 6-O-caffeoyl-beta-D-fructofuranosyl-(2-->1)-alpha-D-glucopyranosid e (1), 1-O-caffeoyl-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyrano side (2), and 1-O-p-hydroxybenzoyl-beta-D-apiofuranosyl-(1-->6)-beta-D-glucop yranos ide (3). Elucidation of the structures of 1-3 was based on the interpretation of FABMS and 1D and 2D NMR spectra. Compounds 1 and 2 were found to be moderately active as antioxidants in the DPPH test and metmyoglobin test.

Antioxidants↗
PubMed1999

Na,K-ATPase mRNA beta 1 expression in rat myocardium--effect of thyroid status.

The abundance of Na,K-ATPase and its alpha and beta subunit mRNAs is upregulated in cardiac and other target tissue by thyroid hormone (T3). Multiple Na,K-ATPase mRNA beta 1 species encoding an identical beta 1 polypeptide are expressed in the heart. The different mRNA beta 1 species result from utilization of two transcription start-sites in the first exon and multiple (five) poly(A) signals in the terminal exon of the beta 1 gene. In the present study we identify the mRNA beta 1 species that are expressed in rat ventricular myocardium under basal conditions, and determine whether they are differentially regulated by T3. mRNA beta 1 species were identified by 3'-RACE followed by DNA sequencing, and by Northern blotting using probes derived from different regions of rat cDNA beta 1. Five mRNA beta 1 species are expressed in rat heart: mRNA beta 1 species that are initiated at the first transcription start-site and end at the first, second and fifth poly(A) sites (resulting in mRNAs of 1630, 1810, and 2780 nucleotides), and mRNA beta 1 species initiated at the second transcription start-site and ending at the second and fifth poly(A) sites (resulting in mRNAs of 1500 and 2490 nucleotides); in order of increasing length, the five mRNAs constitute 0.04, 0.15, 0.38, 0.11 and 0.32 of total mRNA beta 1 content. In hypothyroid rats (induced by addition of propyl-thiouracil to the drinking water for 3 weeks), total mRNA beta 1 content decreased to 0.18 euthyroid levels, which was associated with a disproportionate 7.5-fold decrease in the abundance of the longest transcript (P < 0.05); transcripts initiating at the first transcription start-site and ending at the second poly(A) signal in hypothyroid hearts were 0.26 euthyroid levels (P < 0.05). Hyperthyroidism induced by injection of normal rats with three doses of 100 micrograms T3/100 g body weight every 48 h resulted in an overall approximately 2-fold increase in mRNA beta 1 content with no change in the fractional contribution of any of the mRNA beta 1 species. The results indicate a complex heterogeneity in the expression of mRNA beta 1 in myocardium.

Animals↗
PubMed1999

Spontaneous CSF rhinorrhoea secondary to a middle cranial fossa defect.

Spontaneous cerebrospinal fluid rhinorrhoea is a clinical entity that is difficult to both diagnose and treat. A case in a 56-year-old woman with a defect in the lateral wall of the sphenoid sinus and middle cranial fossa floor is presented. Pathogenesis and management of this rare condition are discussed. Copyright 1999 Harcourt Publishers Ltd.

Journal Article↗
PubMed1999

A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner.

We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T2-weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner.

Artifacts↗
PubMed1999

Regulation of Na/K-ATPase gene expression by thyroid hormone and hyperkalemia in the heart.

Hypothermic hyperkalemic circulatory arrest has been widely used for myocardial protection during heart surgery. Recent data showed that administration of triiodo-L-thyronine (T3) postoperatively enhanced ventricular function. The effect of hyperkalemic arrest in conjunction with thyroid hormone on the plasma membrane enzyme sodium/potassium-adenosine triphosphatase (Na/K-ATPase), was determined in cultured neonatal rat atrial and ventricular myocytes. Exposure of ventricular myocytes to hyperkalemic medium (50 mM KCl) in the absence of T3 increased expression of the Na/K-ATPase catalytic subunit mRNAs, alpha1 and alpha3 isoforms, by 1.9- and 1.5-fold, respectively (p<0.01), which were accompanied by similar increases (1.4- and 1.8-fold) in protein content. Addition of T3 to the hyperkalemic cultures attenuated these increases in Na/K-ATPase mRNA isoforms to levels of expression observed in cells treated with T3 (10(-8) M) alone. Similarly, expression of the alpha1 mRNA isoform in atrial myocytes was increased (p<0.05) by hyperkalemic conditions, and T3 treatment attenuated this effect. In contrast, although expression of the Na/K-ATPase beta1 mRNA in both atrial and ventricular myocytes was significantly increased by hyperkalemia, addition of T3 did not prevent the hyperkalemic response, and in atrial myocytes T3 significantly increased beta1 mRNA expression 1.8-fold. These results show that expression of cardiac Na/K-ATPase is regulated by T3 and hyperkalemia in an isoform and chamber specific manner, and suggest that use of hyperkalemic cardioplegia during heart surgery may alter plasma membrane ion function.

Animals↗
PubMed1999

Biodiversity and bioseparation of HIV-1 envelope glycoproteins.

Since 1984, studies from almost every branch of modern biology have filled in many gaps in our knowledge of human immunodeficiency virus type 1 (HIV-1). This review focuses on studies of biodiversity and bioseparation of HIV-1 envelope glycoproteins from the vaccine development point of view. It presents an updated picture of different systems for producing either native or recombinant HIV-1 envelope glycoproteins for the preparation of vaccine candidates. The prevention of HIV-1-associated disease is highly relevant to the abrogation of the neoplastic processes associated with this pathogen.

AIDS Vaccines↗
PubMed1999

Performance evaluation of microPET: a high-resolution lutetium oxyorthosilicate PET scanner for animal imaging.

UNLABELLED: A new dedicated PET scanner, microPET, was designed and developed at the University of California, Los Angeles, for imaging small laboratory animals. The goal was to provide a compact system with superior spatial resolution at a fraction of the cost of a clinical PET scanner. METHODS: The system uses fiberoptic readout of individually cut lutetium oxyorthosilicate (LSO) crystals to achieve high spatial resolution. Each microPET detector consists of an 8 x 8 array of 2 x 2 x 10-mm LSO scintillation crystals that are coupled to a 64-channel photomultiplier tube by optical fibers. The tomograph consists of 30 detectors in a continuous ring with a 17.2-cm diameter and fields of view (FOVs) of 11.25 cm in the transaxial direction and 1.8 cm in the axial direction. The system has eight crystal rings and no interplane septa. It operates exclusively in the three-dimensional mode and has an electronically controlled bed that is capable of wobbling with a radius of 300 microm. We describe the performance of the tomograph in terms of its spatial, energy and timing resolution, as well as its sensitivity and counting-rate performance. We also illustrate its overall imaging performance with phantom and animal studies that demonstrate the potential applications of this device to biomedical research. RESULTS: Images reconstructed with three-dimensional filtered backprojection show a spatial resolution of 1.8 mm at the center of the FOV (CFOV), which remains <2.5 mm for the central 5 cm of the transaxial FOV. The resulting volumetric resolution of the system is <8 microL. The absolute system sensitivity measured with a 0.74 MBq (20 microCi) 68Ge point source at the CFOV is 5.62 Hz/kBq. The maximum noise equivalent counting rate obtained with a 6.4-cm diameter cylinder spanning the central 56% of the FOV is 10 kcps, whereas the scatter fraction is 37% at the CFOV for an energy window of 250-650 keV and the same diameter cylinder. CONCLUSION: This is the first PET scanner to use the new scintillator LSO and uses a novel detector design to achieve high volumetric spatial resolution. The combination of imaging characteristics of this prototype system (resolution, sensitivity, counting-rate performance and scatter fraction) opens up new possibilities in the study of animal models with PET.

Animals↗
PubMed1999

[Analysis on the epidemic characterization and trend of AIDS in Fujian Province].

OBJECTIVE: To analysed the epidemic characterization and trend of AIDS in Fujian Province based on data obtained from HIV sero-survallance, HIV-1 subtyping and epidemiological survey. METHODS: Serum samples collected from people in high risk groups and specific subgroups were examined for antibody against human immunodeficiency virus (HIV). Epidemiological investigation was conducted toward people who were sero-positive. Clinical data on patients with AIDS were also collected. Peripheral blood mononuclear cells (PBMCs) obtained from HIV-1 infectious and patients with AIDS were used for DNA amplification between C2-V3 region by PCR. The amplified products were sequenced to identify HIV-1 subtypes. RESULTS: From January 1987 through the end of December 1997, a total number of 569,873 serum samples from high risk groups and specific subgroups including blood donors and people that travelling abroad frequently were examined for HIV antibody Seventy people with HIV-1 sero-positive were identified, accounting for 0.12/1000 of the total detected numbers. Among them, 21 patients with AIDS in which 18 cases had died. HIV/AIDS cases were mainly distributed along the coastal cities as Fuzhou, Quanzhou and Xiamen where economic development was growing rapidly. Most cases were infected abroad and spreading HIV to the country through sexual transmission. Clinical data showed that early syndromes and reversal fever of patients with AIDS were seen but survival time was short. Nucleotide sequencing showed that HIV-1 strains in the province were most subtype E. CONCLUSION: HIV epidemic in the province will mainly be spreading among people with sexually promiscuous behaviors.

Acquired Immunodeficiency Syndrome↗
PubMed1999

[Perioperative use of peripherally inserted central catheter for parenteral nutrition in patients with abdominal malignancy].

OBJECTIVE: To evaluate the use of peripherally inserted central catheter(PICC) in perioperative patients with abdominal malignancies for parenteral nutrition. METHODS: PICC was performed in 33 patients while subclavicular vein insertion in 30 patients for comparison in order to analyse prospectively the advantages and disadvanges of PICC. RESULTS: There was no difference in the rate of success of catheter placement and infection between PICC and the "subclavicular" insertion (P > 0.05), but PICC had significantly longer indwelling time than that of the "subclavicular" insertion (P < 0.05). There were less risks associated with PICC insertions, but the flow rate of was lower(p < 0.05). CONCLUSIONS: PICC can be widely used on account of its longer indwelling time, easy and safe insertion.

Abdominal Neoplasms↗
PubMed1999

[Determination of stilbene in radix Polygoni multiflori by HPLC and its stability study].

OBJECTIVE: To develop a HPLC method for determining stilbene in Radix Polygoni Multiflori and studying its stability. METHOD: HPLC conditions: An Econosphere C18 column, a mixture of methanol-water(30:70) as mobile phase, and UV detection at 310 nm. In addition, the stability of stilbene was studied at high temperature and in acidic solution. RESULT: The linear range of calibration curve was 2.24 x 10(-2)-1.12 x 10(-1) micrograms(n = 6) with a correlation coefficient of 0.99998, the average recovery with RSD being 99.96% +/- 1.54%. CONCLUSION: The method is sensitive, accurate and speedy. Stilbene in aqueous solution is stable, but high temperature(80 degrees C) tends to affect the stability. In acidic solution no stability can be found.

Drug Stability↗