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Biomedical subjects

G R Zhang

Publications and source records attributed to G R Zhang.

At least 19 recordsLinked to original sources
PubMed2001

Enhanced reporter gene expression in the rat brain from helper virus-free HSV-1 vectors packaged in the presence of specific mutated HSV-1 proteins that affect the virion.

Herpes simplex virus (HSV-1) gene expression is hypothesized to shut off promoters in HSV-1 vectors, but in a helper virus-free HSV-1 vector system, a number of promoters support only short-term expression. Thus, recombinant gene expression remains short-term in the absence of approximately 99% of the HSV-1 genome. To resolve this paradox, we hypothesized that specific HSV-1 proteins that affect the virion can shut off recombinant gene expression. This study evaluated expression from HSV-1 vectors, containing neuronal-specific promoters, that were packaged in the presence of specific mutated HSV-1 proteins that affect the virion. The mutated HSV-1 proteins that were examined included two protein kinases (U(L)13 and U(S)3), the virion host shut-off factor (vhs), the transactivator of immediate early promoters (VP16), and a virion protein that affects RNA metabolism (U(S)11). Helper virus-free packaging could occur in the presence of each mutated protein alone or specific combinations of two or three mutated proteins. In BHK and PC12 cells, vectors packaged in the presence of each mutated protein increased ( approximately 2-fold) the level of expression per cell, and vectors packaged in the presence of specific combinations of mutated proteins supported larger (4-7-fold) increases. In the rat striatum, vectors packaged in the presence of a mutated U(S)3 displayed enhanced gene transfer (13-18-fold increases in the number of cells at 4 days), and vectors packaged in the presence of mutated U(L)13 or VP16 enhanced long-term expression (2 months). Vectors packaged in the presence of mutated vhs or U(S)11 displayed minimal changes in expression.

Animals↗
PubMed2001

General strategy for constructing large HSV-1 plasmid vectors that co-express multiple genes.

Herpes simplex virus type 1 (HSV-1) plasmid vectors have a number of attractive features for gene transfer into neurons. In particular, the large size of the HSV-1 genome suggests that HSV-1 vectors might be designed to co-express multiple genes. Here, we report a general strategy for constructing large HSV-1 plasmid vectors that co-express multiple genes. Each transcription unit is linked to an antibiotic resistance gene, and genetic selections are used to assemble large vectors. Using this strategy, we constructed large (26 or 31 kb) HSV-1 vectors that contain two transcription units and two or three genes. These vectors were efficiently packaged into HSV-1 particles using a helper virus-free packaging system. The resulting vector stocks supported the expression of two or three genes in both cultured cells and the rat brain. Potential applications of HSV-1 vectors that co-express multiple genes are discussed.

Gene Expression Regulation, Viral↗
PubMed2000

A tyrosine hydroxylase-neurofilament chimeric promoter enhances long-term expression in rat forebrain neurons from helper virus-free HSV-1 vectors.

Helper virus-free herpes simplex virus (HSV-1) plasmid vectors are attractive for neural gene transfer, but a promoter that supports neuronal-specific, long-term expression is required. Although expression from many promoters is unstable, a 6.8-kb, but not a 766-bp, fragment of the tyrosine hydroxylase (TH) promoter supports long-term expression. Thus, 5' upstream sequences in this promoter may enhance expression. In this study, we evaluated expression from vectors that contain 5' upstream sequences from this promoter (-0.5 to -6.8 kb) inserted at the 5' end of either a neurofilament heavy subunit (NF-H) promoter or the cytomegalovirus (CMV) immediate early promoter. The TH-NFH promoter supported expression for 6 months in the striatum, 2 months in the hippocampus, and for 1 month in both perirhinal and postrhinal cortex (the longest time points examined). Expression was targeted to neurons. The enhanced expression may require specific sequences in the TH promoter fragment because replacing this fragment with a similar sized fragment of bacteriophage lambda DNA did not enhance expression. The reverse orientation of the TH promoter fragment also enhanced expression. Insertion of insulators from the chicken beta-globin locus between the TH-NFHlac transcription unit and the vector backbone may support a modest additional enhancement in expression. Other eucaryotic sequences may also enhance expression; a S. cerevisiae (40-kb fragment)-NFH promoter enhanced expression. In contrast, the TH-CMV promoter did not enhance expression. Thus, the TH-NFH promoter may support some physiological studies that require long-term expression in forebrain neurons.

Animals↗
PubMed2000

Fifty-one kilobase HSV-1 plasmid vector can be packaged using a helper virus-free system and supports expression in the rat brain.

Herpes simplex virus type 1 (HSV-1) plasmid vectors have a number of attractive features for gene transfer into neurons. In particular, the large size of the HSV-1 genome suggests that HSV-1 vectors might be designed to accommodate large inserts. We now report the construction and characterization of a 51 kb HSV-1 plasmid vector. This vector was efficiently packaged into HSV-1 particles using a helper virus-free packaging system. The structure of the packaged vector DNA was verified by both Southern blot and PCR analyses. A vector stock was microinjected into the rat striatum, the rats were sacrificed at 4 days after gene transfer, and numerous X-gal positive striatal cells were observed. This 51 kb vector was constructed using general principles that may support the routine construction of large vectors. Potential applications of such HSV-1 vectors include characterizing large promoter fragments or genomic clones and co-expressing multiple genes.

Animals↗
PubMed1999

Improved titers for helper virus-free herpes simplex virus type 1 plasmid vectors by optimization of the packaging protocol and addition of noninfectious herpes simplex virus-related particles (previral DNA replication enveloped particles) to the packaging procedure.

A helper virus-free herpes simplex virus type 1 (HSV-1) plasmid vector system has potential for both gene therapy and physiological studies, but relatively low titers have complicated use of this system. In this article, the packaging efficiency was improved by optimizing the packaging protocol and by adding noninfectious HSV-1-related particles, i.e., previral DNA replication enveloped particles (PREPs), during the packaging procedure. PREPs contain many of the tegument proteins that are thought to enhance an HSV-1 infection. Use of both the optimized packaging protocol and the PREPs resulted in an approximately 50-fold increase in the titer, and five different HSV-1 vectors were packaged using this procedure. A purified vector stock (7.8x10(8) infectious vector particles/ml) was microinjected into the striatum, the rats were sacrificed 4 days after gene transfer, and the brains were found to contain an average of approximately 6740 X-Gal-positive striatal cells. This improved packaging procedure may augment use of this vector system.

Animals↗
PubMed1995

[Study on Chinese herb incense to disinfect wards' air].

The purpose of this study was to find out a proper way to do the air sterilization in the wards. In this study, Chinese herb-burn-incense was used to different wards. Its effect was compared with routine air sterilization methods such as ultraviolet radiator, formaldehyde, and lactiacid method. The bacterial culture of the air was done. The result indicated that Chinese herb-burn-incense not only had the same effect as routine methods in air sterilization but also had no irritation to the patients.

China↗
PubMed1994

[Relationship between syndrome differentiation and blood total fibrinolytic activity, superoxide dismutase and albumin in nephrosis syndrome].

Relationship between the Syndrome Differentiation and total fibrinolytic activity (TFA), superoxide dismutase (SOD), serum albumin (Alb) was observed in 118 pediatric patients with nephrosis syndrome. The results suggested that there was significant difference between Damp-Heat type and Spleen Deficiency type in terms of blood TFA, SOD and serum Alb. Very significant positive correlation was found between serum Alb and TFA, P < 0.01. The level of TFA in pediatric patients with edema was significantly lower than that in normal children, the more the degree of edema, the more the level of TFA activity. It was shown that there would be possibility to find intrinsic connection between Syndrome Differentiation and laboratory findings.

Adolescent↗
PubMed1993

Countercurrent immunoelectrophoresis for diagnosis of acute bacterial pneumonia in Chinese children.

Countercurrent immunoelectrophoresis (CIE) with H. influenzal type b(Hib) and Pneumococci Omni antisera was performed on serum and concentrated urine and pleural fluid samples from 100 patients with acute pneumonia in Beijing Children's Hospital. Thirty-one patients were investigated by bacteriologic techniques (blood culture and pleural fluid culture). CIE was positive in 29/100 (29%) of cases of Hib, 13/100 (13%) of cases for pneumococci. Overall, bacterial causes of pneumonia were diagnosed by CIE in 41/100 (41%) cases. Antigens were detected in 5/90 (5.6%) serum samples, in 36/87 (41.5%) concentrated urine samples, and in 1/2 (50%) samples of pleural fluid. Only one Hib strain was found by pleural fluid culture. The contamination rate of bacterial culture in this group was high (5/31 cases, 16.1%). Therefore, traditional bacteriologic techniques are of very limited value for diagnosing pneumonia in Chinese children. The results showed that bacterial pathogen, especially Hib and Pneumococci, are very common and important causes of pediatric pneumonia in China.

Antigens, Bacterial↗
PubMed1991

Oxalyl-CPG: a labile support for synthesis of sensitive oligonucleotide derivatives.

A procedure is described for linking nucleosides covalently to controlled pore glass or cross-linked polystyrene supports by means of an oxalyl anchor. Though stable to triethylamine and diisopropylamine, the nucleoside-oxalyl link can be cleaved within a few minutes at room temperature with ammonium hydroxide in methanol. This new anchor can be used in automated synthesis of conventional oligonucleotides. The primary value, however, is that it enables one to employ solid support methodology to synthesize a variety of base-sensitive oligonucleotide derivatives, as illustrated here by synthesis of oligomers with base protecting groups intact and with methyl phosphotriester groups at the internucleoside links.

Base Sequence↗
PubMed1989

Cholesteryl-conjugated oligonucleotides: synthesis, properties, and activity as inhibitors of replication of human immunodeficiency virus in cell culture.

A family of oligonucleotides and phosphorothioate oligonucleotide analogues was synthesized with a cholesteryl group tethered at the 3'-terminal internucleoside link. This modification, introduced to enhance interaction of the polyanions with cell membranes, significantly increases the antiviral activity of the oligomers, as judged by inhibition of syncytia formation and expression of viral proteins p17, p24, and reverse transcriptase for human immunodeficiency virus 1 in Molt-3 cells. In the most favorable case, with a 20-mer cholesteryl-phosphorothioate derivative, complete inhibition by all assays was obtained with an oligomer concentration of 0.2 microM. Even decamers were active, and some antiviral activity was observed for a heptanucleotide cholesteryl-phosphorothioate derivative, which binds very poorly to complementary oligonucleotides. These facts, and the finding that the activity of the phosphorothioate decamers does not correlate with a specific sequence, suggests that a mechanism other than "antisense inhibition" may be operative in these systems.

Antiviral Agents↗
PubMed1989

Sequential observation of clinical and karyotypic evolution in a patient with myelodysplastic syndrome.

This paper reports an interesting case of myelodysplastic syndrome (MDS), whose bone marrow karyotype at diagnosis was 46, XY, t(16;17) (q12;q25). Fourteen months later, the disease transformed into erythroleukemia, and several correlative clones with hyperdiploid appeared at the same time. Thus, we consider that detecting karyotypic evolution may help evaluate the prognosis of MDS.

Anemia, Refractory↗