Biomedical subjects

Y Zhang

Publications and source records attributed to Y Zhang.

At least 181 records · Page 10Linked to original sources

PubMed2005

Transient overexpression of gamma interferon promotes Aspergillus clearance in invasive pulmonary aspergillosis.

Cytokines are critical molecules necessary for normal lung pathogen host defences. Gamma interferon (IFN-gamma) and T1-phenotype immune responses are important components of host defence against Aspergillus. Therefore, we hypothesized that transient overexpression of IFN-gamma within the lung could augment host immunity against Aspergillus. Here it was showed that intranasal administration of 5 x 10(7) colony-forming units (CFU) of Aspergillus fumigatus (Af ) induced the expression of IFN-gamma. Mice were intranasally (i.n) administrated with 5 x 10(8) PFU of a recombinant adenovirus vector containing the murine IFN-gamma cDNA (AdmIFN-gamma), and challenged 24 h later with Af. We observed that i.n. administration of AdmIFN-gamma resulted in about a fourfold increase in levels of IFN-gamma and IL-12 within the lung, about a 75% reduction in lung fungal contents at day 2 and a more than threefold higher survival rate in the AdmIFN-gamma-treated group compared to the controls (P < 0.01). This protection effect was not found when AdmIFN-gamma was i.p. administrated. Alveolar macrophages and lung leucocytes isolated from i.n. AdmIFN-gamma-treated animals displayed enhanced killing of intracellular Aspergillus organisms ex vivo. These results demonstrate that transient overexpression of IFN-gamma could augment host defence against Aspergillus.

Adenoviridae↗

PubMed2005

The glycans deficiencies of macromolecular IgA1 is a contributory factor of variable pathological phenotypes of IgA nephropathy.

Recent evidence has suggested that IgA1-containing macromolecules and the glycosylation of IgA1 in sera from patients with IgAN might involve the pathogenesis of IgAN. However, whether the different histological phenotypes can be attributed or not to the aberrant glycosylation of macromolecular IgA1 has not yet been elucidated. The aim of the current study is to investigate the glycosylation of IgA1 molecules in serum IgA1-containing macromolecules and their association with pathological phenotypes of IgAN. Sera was collected from 40 patients with IgAN and 20 donors. Twenty patients had mild mesangial proliferative IgAN, the remaining 20 had focal proliferative sclerosing IgAN. Polyethylene glycol 6000 was used to precipitate the macromolecules from sera of patients and controls. Biotinylated lectins were used in an enzyme-linked immunosorbent assay (ELISA) to examine different glycans on IgA1 molecules. The alpha2,6 sialic acid was detected by elderberry bark lectin (SNA) and the exposure of terminal galactose (Gal) and N-acetylgalactosamine (GalNAc) were detected by Arachis hypogaea (PNA) and Vilsa villosa lectin (VVL), respectively. The IgA1 glycans levels corrected by IgA1 concentrations were compared between patients and controls. Reduced terminal alpha2,6 sialic acid of IgA1 (79.89 +/- 25.17 versus 62.12 +/- 24.50, P = 0.034) was demonstrated only in precipitates from sera of patients with focal proliferative sclerosing IgAN, compared with those from controls. Reduced galactosylation of IgA1 molecules in precipitates was demonstrated in patients with both mild mesangial proliferative IgAN and focal proliferative sclerosing IgAN compared with normal controls (24.52 +/- 18.71 versus 76.84 +/- 32.59 P = 0.000 and 33.48 +/- 25.36 versus 76.84 +/- 32.59 P = 0.000). However, no significant difference was found in IgA1 glycosylation in the supernatant between patients and normal controls (P > 0.05). The glycosylation deficiency of IgA1 existed only in serum IgA1-containing macromolecules of patients with IgAN, and was associated with the renal pathological phenotypes. This suggests that aberrant glycosylation of IgA1 in serum macromolecules might be a contributory factor in the pathogenesis of IgAN.

Acetylgalactosamine↗

PubMed2005

Radiation-induced changes in gene expression in the silkworm revealed by serial analysis of gene expression (SAGE).

Serial analysis of gene expression (SAGE) was used to examine the profile of expressed genes during embryonic development in the domesticated silkworm, Bombyx mori, after irradiation with Cobalt-60. A comparison of the SAGE sequence tags derived from irradiated embryos with those from normal embryos revealed 673 differentially expressed genes (P < 0.01 and at least three folds change). Of these, 292 genes were highly expressed in normal embryos and 381 genes were highly expressed in irradiated embryos. These results provide valuable information for understanding the mechanisms of radiation-induced changes in gene expression. In addition, it was noted that the generation of longer cDNA fragments from SAGE tags is an efficient way to identify genes, thereby facilitating the analysis of large numbers of unknown genes.

Animals↗

PubMed2005

Secretory expression of recombinant proteins in an attenuated Vibrio anguillarum strain for potential use in vaccines.

Vibrio anguillarum is an important bacterial fish pathogen responsible for epizootics in both marine and freshwater fish worldwide. Studies on pathogenic V. anguillarum has shown that its virulence is mediated by a 65 kb endogenous pJM1-like plasmid, which encodes an efficient iron uptake system. The plasmid-free derivative of wild V. anguillarum was found to be greatly attenuated and elicited a good protection against wild V. anguillarum in fish. In this study, a plasmid-free derivative MVAV6201, an effective live vaccine candidate, was used as a carrier strain to achieve the secretory delivery of recombinant proteins in V. anguillarum. The secretion mechanism was based on the Escherichia coli alpha-haemolysin (HlyA) transport system. The recombinant proteins were fused with the alpha-haemolysin secretion signal (HlyAs) and expressed from the commonly used HlyA secretion vector pMOhly1. Two HlyAs-tagged recombinant proteins, GFP-HlyAs and AngE-HlyAs, were constructed and their secretion characters in V. anguillarum investigated. In the case of GFP-HlyAs, nearly 70% of the total fusion protein was efficiently secreted into culture supernatant, and in the case of AngE-HlyAs, the secretion efficiency was determined to be about 300 microg L(-1) by Western blotting.

Animals↗

PubMed2005

Stromal cells attract B-cell progenitors to promote B-cell-B-cell contact and maturation.

The in vitro differentiation of B-lineage progenitors into Ig-secreting mature B cells has classically required a co-culture system containing lipopolysaccharide (LPS) and stromal cells. We have previously showed that B-lineage progenitors cultured in round-bottomed wells can mature and secrete immunoglobulin M (IgM) on par with cultures containing stromal cells. This clearly demonstrates that any factors essential for progenitor cell maturation can be found in cultures containing media, serum, LPS and B-cell progenitors. However, stromal cells are important for the maturation observed when cells are cultured in flat-bottomed wells. We hypothesized that stromal cells may attract B-cell progenitors and promote contacts between responsive cells, a phenomenon that is mimicked by the cultures in round-bottomed wells. In this study, we explore how stromal cells accomplish these functions. We show that stromal cells attract B-cell progenitors in a pertussis toxin-sensitive manner. The stromal cell line S17 produces the chemokine CXCL12, which is able to induce the chemotaxis of B-lineage progenitors. Chemotaxis can be blocked by a small peptide inhibitor (T134) of CXCR4, the CXCL12 receptor. Further, disrupting chemotaxis can reduce the supportive role played by S17 when B-lineage progenitors are cultured in flat-bottomed wells.

Animals↗

PubMed2005

DNA vaccination using bacillus Calmette-Guerin-DNA as an adjuvant to enhance immune response to three kinds of swine diseases.

In order to enhance the immune efficacy of DNA vaccination, experiments were conducted to investigate the regulating effects of Bacillus Calmette-Guerin (BCG)-DNA as an adjuvant on immune responses of mice against foot-and-mouth disease (FMD), Aujeszky's disease (AjD) and classical swine fever (CSF). BCG-DNA was purified from BCG by ion-exchange chromatography. Three DNA vaccines (pVSG, pVgD and pVE2) against the respective infection were constructed, and BCG-DNA was coimmunized to mice by muscle injection. The results showed that titres of specific immunoglobulin (Ig)G to the vaccines mounted remarkably in the sera of the adjuvant covaccinated mice (P < 0.01). Antibody isotype IgG2a and IgG1 also increased, respectively, in mice coimmunized with BCG-DNA compared with those of the control groups (P < 0.01). Cellular immune cytokine interferon-gamma and cytotoxic T lymphocytes were detected in coimmunized BCG-DNA groups (P < 0.05). Whereas interleukin-4, humoral immune cytokine, was not significant (P > 0.05). These results suggest that codelivery of BCG-DNA with DNA vaccines against FMD, AjD and CSF can enhance the induction of antigen-specific, especially, cell-mediated immunity.

Adjuvants, Immunologic↗

PubMed2005

Recurrence of symptomatic atrial fibrillation after successful catheter ablation of atrioventricular accessory pathways: a multivariate regression analysis.

The primary aim of this study is to investigate the factors related to the recurrence of atrial fibrillation (AF) after a successful ablation of atrioventricular accessory pathway. Thirty-seven patients with spontaneous AF (study group) were selected from 401 consecutive patients who underwent radiofrequency catheter ablation of atrioventricular accessory pathway. A multivariate regression analysis was used in order to evaluate the relationships between AF recurrence and patients' age, sex, atrial size, left ventricular function, location of accessory pathways, heart rate during atrioventricular re-entrant tachycardia and atrial vulnerability (induction of sustained AF) after a successful ablation. Atrioventricular accessory pathway was abolished in 36 of the study group patients and 351 of the control group patients. During the follow-up of 36 +/- 11 months, four patients (11.1%) from the study group experienced sustained AF. Multivariate regression analysis showed that, in patients with pre-ablation AF, older age and post-ablation atrial vulnerability were the only independent predictive factors for AF recurrence. We concluded that radiofrequency catheter ablation of atrioventricular accessory pathway greatly reduces the risk of AF in patients who had a history of symptomatic AF. Older patients and patients with inducible AF after accessory pathway ablation are at an increased risk of AF recurrence. These patients should be closely monitored after successful ablation of atrioventricular accessory pathways.

Adult↗

PubMed2005

Impact of growth factors on in vitro development of caprine oocytes at pre-antral stage.

The objective of this study was to examine the effect of various growth factors such as the epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I) either individually or in association, in the presence of follicle-stimulating hormone (FSH) on the in vitro growth and viability of caprine oocytes at pre-antral stage. Pre-antral follicles were disassociated enzymatically and mechanically from pre-pubertal caprine ovaries after the animals were anaesthetically ovariectomized. Caprine pre-antral follicles in group 1, 2, 3 and 4 were cultured in growth culture medium, growth culture medium + EGF, growth culture medium + IGF-I and growth culture medium + IGF-I + EGF, respectively, for 9 days. The results indicated that EGF (50 mg/l) increased the survival rate of oocytes, but decreased the growth rate of oocytes; IGF-I (100 mg/l) effectively maintained the survival of oocytes and stimulated their growth; IGF-I (100 mg/l) and EGF (50 mg/l) in combination produced a higher effect on both the survival and the growth rate of oocytes than IGF-I or EGF alone. Conclusively, the growth factors can effectively maintain the survival of caprine oocytes from pre-antral follicles and regulate their growth in culture. EGF and IGF-I in association could synergically meliorate the culture system of caprine pre-antral follicles.

Animals↗

PubMed2005

Novel insight into VOC removal performance of photocatalytic oxidation reactors.

UNLABELLED: A general model has been developed for analyzing the removal of volatile organic compounds (VOCs) by photocatalytic oxidation (PCO) reactors, taking into consideration of the photocatalytic (surface) reaction and the convective mass transfer coefficients including allowance for their spatial dependence. On this basis, a novel insight into VOC removal performance of PCO reactors is presented. The key parameter for evaluating PCO reactor VOC removal performance is the number of the mass transfer unit (NTU(m)), which is shown to be a simple linear product of three dimensionless parameters: the ratio of the reaction area to the cross-sectional area of the flow channel (A*), the Stanton number of mass transfer (St(m)), and the reaction effectiveness (eta). The A* represents the geometric and structural characteristic of a PCO reactor. The St(m) shows the synergistic degree of alignment between the fluid and mass flow fields, and reflects the convective mass transfer rate of the reactor. The eta, describes the relative intensity between the PCO reaction rate and the mass transfer rate. By using the relationship and the parameters, the influence of various factors on the VOC removal performance, the bottleneck for improving the performance and design of a PCO reactor can be determined. Three examples are used to illustrate the application of our proposed model. It is found that the VOC removal bottleneck is the reaction rate for honeycomb type reactor, while mass transfer rate for light-in-tube type reactor. With six fins the fractional conversion of a light-in-tube reactor increases about 70% relative to the one without any fins. PRACTICAL IMPLICATIONS: Indoor air quality problem caused by volatile organic compounds (VOCs) have annoyed people for many years. Photocatalytic oxidation (PCO) appears to be a promising technique for destroying VOCs in indoor air. With the model and the novel insight presented in this paper, the influence of various factors on the VOC removal performance can be determined. And the bottleneck for improving the performance of a PCO reactor can be easily identified. These are helpful for designing high performance PCO reactors and optimizing their operative performance.

Air Pollution, Indoor↗

PubMed2005

Array based CGH and FISH fail to confirm duplication of 8p22-p23.1 in association with Kabuki syndrome.

BACKGROUND: Kabuki (Niikawa-Kuroki) syndrome comprises a characteristic facial appearance, cleft palate, congenital heart disease, and developmental delay. Various cytogenetically visible chromosomal rearrangements have been reported in single cases, but the molecular genetic basis of the condition has not been established. A recent report described a duplication of 8p22-p23.1 in 13/13 patients. OBJECTIVE: To determine the frequency of an 8p duplication in a cohort of patients with Kabuki syndrome. METHODS: An 8p duplication was sought using two independent methods--array based comparative genomic hybridisation (aCGH) and fluorescence in situ hybridisation (FISH)--in 15 patients with a definitive clinical diagnosis of Kabuki syndrome. RESULTS: No evidence for a duplication of 8p was obtained by FISH or aCGH in any of the 15 patients. CONCLUSIONS: 8p22-p23.1 duplication may not be a common mechanism for Kabuki syndrome. Another genetic abnormality may be responsible for the aetiology in many patients.

Abnormalities, Multiple↗

PubMed2005

Clinical [corrected] and pathological characteristics of Chinese patients with antineutrophil cytoplasmic autoantibody associated systemic vasculitides: a study of 426 patients from a single centre.

BACKGROUND: Antineutrophil cytoplasmic autoantibodies (ANCA) are serological markers of ANCA associated systemic vasculitides (AASV), which is one of the most common multisystem autoimmune diseases. Features of Chinese patients with AASV have not been fully investigated. OBJECTIVE: To analyse the clinical and pathological characteristics of Chinese patients with AASV. METHODS: 426 Chinese patients with AASV diagnosed in the past eight years were retrospectively studied and their clinical and pathological data were analysed. RESULTS: Of the 426 patients, 87 (20.4%) were Wegener's granulomatosis, 337 (79.1%) were microscopic polyangiitis and two (0.5%) were Churg-Strauss syndrome. Only 201 of 426 (47.2%) patients were diagnosed within three months. Clinically, the patients had multisystem involvement. Altogether 371 of 426 (87.1%) had kidney involvement and 260 of 426 (61.0%) had lung involvement. The prevalences of renal involvement and fatigue were significantly higher in patients with MPO-ANCA than that in patients with PR3-ANCA; the prevalences of ophthalmic, nasal involvement, rash, and arthragia were significantly higher in patients with PR3-ANCA than those in patients with MPO-ANCA. The one and five year death rates were 13.1% and 22.4%, respectively. The percentage of patients progressing to end stage renal disease at one and five years was 15.9% and 27.1%, respectively. CONCLUSIONS: AASV is not a rare autoimmune disease in Chinese people. Kidney and lung were the most vulnerable organs. For patients with multiorgan damage, an ANCA test should be performed to make an early diagnosis and to start treatment in time.

Adolescent↗

PubMed2005

A matched, case-control study of the association between Schistosoma japonicum and liver and colon cancers, in rural China.

A study of liver and colon cancers and their association with a previous diagnosis of schistosomiasis was performed in rural Sichuan, China. The data analysed came from 127 liver-cancer and 142 colon-cancer patients, each matched, by age, gender, hospital and township, with one or two controls. The cancer cases were identified from the hospital records of three Sichuan counties (all of which have some level of endemic schistosomiasis japonicum): Meishan (66 liver and 54 colon cases), Pujiang (16 liver and 22 colon cases) and Xichang (45 liver and 66 colon cases). Each control was selected using the hospital records for the same year the matched case of cancer was diagnosed, when the control had been found to have an illness other than cancer. Previous schistosomal infection was determined by examining the medical records at the county hospitals, searching the records at the local schistosomiasis-control stations or health-surveillance units, and, when no written record could be found, by interviews with the subjects or their relatives. Given the extremely strong association between hepatitis and liver cancer in China, only data from hepatitis-negative pairs were used in the analyses. Previous schistosomal infection was found to be significantly associated with both liver cancer (odds ratio = 3.7; 95% confidence interval = 1.0-13) and colon cancer (odds ratio = 3.3; 95% confidence interval = 1.8-6.1). The results indicate a fraction of disease attributable to schistosomiasis of 24% for colon cancer, and (among the hepatitis-negative population) one of 27% for liver cancer.

Adult↗

PubMed2005

Isolation and characterization of H3N2 influenza A virus from turkeys.

Five 34-wk-old turkey breeder layer flocks in separate houses of 2550 birds each in a single farm in Ohio experienced a drop in egg production from late January to early February 2004. Tracheal swabs (n = 60), cloacal swabs (n = 50), and convalescent sera (n = 110) from the flocks were submitted to the laboratory for diagnostics. Virus isolation was attempted in specific-pathogen free embryonating chicken eggs and Vero and MDCK cells. Virus characterization was performed using agar gel immunodiffusion, the hemagglutination test, the hemagglutination inhibition test, the virus neutralization test, reverse transcription-polymerase chain reaction, sequencing, and phylogenetic analysis. A presumptive influenza virus was successfully propagated and isolated on the first passage in MDCK cells, but initially not in Vero cells or specific-pathogen free chicken embryos. After two passages in MDCK cells, it was possible to propagate the isolate in specific-pathogen free chicken embryos. Preliminary sequence analysis of the isolated virus confirmed that it was influenza A virus with almost 100% (235/236) identity with the matrix gene of a swine influenza A virus, A/Swine/Illinois/100084/01 (H1N2). However, it was not possible to subtype the virus using conventional serotyping methods. The results of genetic characterization of the isolated virus showed that it was the H3N2 subtype and was designated as A/Turkey/OH/313053/04 (H3N2). Phylogenetic analysis of the eight gene segments of the virus showed that A/Turkey/OH/313053/04 (H3N2) isolate was most closely related to the triple-reassortant H3N2 swine viruses [A/Swine/WI/14094/99 (H3N2)] that have been circulating among pigs in the United States since 1998, which contains gene segments from avian, swine, and human viruses. The A/Turkey/OH/313053/04 (H3N2) isolated from turkeys in this study was classified as a low pathogenic avian influenza A virus because it only caused a drop in egg production with minor other clinical signs and no mortality.

Animals↗

PubMed2005

Therapeutic potential of TACE inhibitors in stroke.

Stroke is the third leading cause of death and the leading cause of permanent disability in western countries and the incidence of stroke is expected to increase in the foreseeable future due to the ageing population. The effective treatment of stroke remains challenging due to the complexity and heterogenicity of the disease. Recombinant tissue plasminogen activator (rt-PA) is the only FDA-approved therapy for stroke during the first 3 hr after the disease onset. However the risk of hemorrhage and its narrow therapeutic window has limited its use in clinic. Inflammation has been known to play a crucial role in the induction and development of stroke and tumor necrosis factor-alpha (TNF-alpha) is a central player in the initiation of multiple inflammatory cascades. The recent success of three anti-TNF biologics in the clinic for the treatment of rheumatoid arthritis as well as other inflammatory diseases has further validated TNF159nflammation. TNF-alpha has also been shown to be associated with ischemic stroke. Anti-TNF biologics have been shown to be effective in reducing the disease symptoms in various pre-clinical stroke models. Small molecule TNF inhibitors are highly desirable due to the limitations of protein therapeutics. Tumor necrosis factor-alpha-converting enzyme (TACE) is the major sheddase of TNF-alpha and is essential for the generation of soluble, mature TNF-alpha. Thus TACE appears to be an attractive target for development of oral small molecule TNF-alpha inhibitors. This review summarizes the role of TNF-alpha in stroke and the effect of several TACE/MMP inhibitors in pre-clinical stroke models. The data strongly suggest that TACE/MMP inhibitors have great therapeutic potential and may be valuable alternatives in treating stroke in the clinic.

ADAM Proteins↗

PubMed2005

Comparison of nitrification performance and microbial community between submerged membrane bioreactor and conventional activated sludge system.

A submerged membrane bioreactor (SMBR) and a conventional activated sludge system (CAS) were compared in parallel over a period of more than 260 days on treating synthetic ammonia-bearing inorganic wastewater without sludge purge under decreased hydraulic retention times (HRTs). Conversion of NH4(+)-N to NO3(-)-N was achieved with an efficiency of over 98% at an HRT > or = 10 h in the SMBR, while similar performance was obtained at an HRT > or = 20 h in the CAS. Denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) amplified 16S rDNA was used to monitor variations of community structures in the two systems. With the prolongation of operation, the number of DGGE bands in the SMBR gradually increased from the initial 11 bands to the final 22 bands, whereas that in the CAS varied in a range between 13 and 183 Sequence analysis indicates that Nitrosomonas sp. and Nitrospira sp. were the dominating nitrification species responsible for ammonia and nitrite oxidation, respectively. Heterotrophic bacteria like Pseudomonas sp. and Flavobacteria sp. existed in both of the systems although only inorganic wastewater was fed. Substantive accumulation of extracellular polymeric substances (EPS) in the SMBR was confirmed by scanning electron microscopy and EPS analysis.

Ammonia↗

PubMed2005

Muscle and plasma coenzyme Q10 concentration, aerobic power and exercise economy of healthy men in response to four weeks of supplementation.

AIM: To investigate whether 4 weeks of oral supplementation with coenzyme Q10 (CoQ10) would increase its concentration in skeletal muscle, and affect aerobic power (VO2max) and oxygen consumption during submaximal exercise in healthy, physically active men. METHODS: Six volunteers with an average (+/-SD) age of 29.7+/-7.2 years and VO2max of 39.4+/-8.5 mL.kg-1.min-1, participated in a single-blind trial. The experiment consisted of 4 2-week phases, in the order of placebo run-in, CoQ10 supplementation (150 mg daily), CoQ10 (150 mg) plus vitamin E (1,000 IU daily), and placebo wash-out. A three-stage cycle economy test (4 minutes at each of 50, 100, and 150 watts), followed by a VO2max test (25 watts increment every minute till exhaustion), were performed prior to the supplementation and at the end of each phase. Blood samples were taken pre and post each VO2max test, and biopsy samples were obtained from the vastus lateralis muscle pre and post the 4 weeks of CoQ10 supplementation. RESULTS: The plasma CoQ10 concentration was significantly elevated by the supplementation (P<0.05), however, it did not vary significantly pre and post each exercise test (P>0.05). The muscle CoQ10 concentration, VO2max ventilatory threshold, exercise economy and oxygen deficit showed no significant changes in response to the supplementation. CONCLUSION: It was speculated that the non-significant effects of supplementation in healthy, non CoQ10-deficient men could be due to either that the mitochondrial membrane is normally saturated with CoQ10, or that the selected exercise testing protocol and variables were not sensitive enough to detect the effects.

Adult↗

PubMed2005

Inhibition of hepatitis B virus replication by recombinant small interfering RNAs.

RNA interference (RNAi) is a biological phenomenon in which introduction of a small, double-stranded interfering RNAs (siRNAs) into a cell causes a specific degradation of homologous single-stranded RNA. siRNA can be delivered into the cell by different approaches including synthetic RNA, in vitro transcribed RNA and RNA transcribed from polymerase III-based recombinant vectors. As hepatitis B (HB) represents a worldwide health problem, we attempted to develop a fast and easy approach to generation and screening of specific siRNA-targeted HB virus (HBV) genes. Using PCR amplification, specific siRNA expression cassettes (SECs) were developed and used to generate effective siRNAs against HB virus (HBV) replication and gene expression in mammalian cells. After screening, we identified two SECs that expressed siRNAs which efficiently decreased the level of HBV pre-c/c gene expression in transfected Bel-7402 cells by 81.9% and 87.3%, respectively. In addition, the level of HBV DNA was decreased by 83.5% and 85.2% in HepG2 2.2.15 cells, respectively. This study provides (i) a new effective application of RNA interference to study viral gene function and viral replication and (ii) a new tool for the prevention and treatment of human HBV infection.

DNA, Viral↗

PubMed2004

Gibberellin inhibitors improve embryogenic tissue initiation in conifers.

Somatic embryogenesis (SE), the most promising technology to multiply high-value coniferous trees from advanced breeding and genetic engineering programs, is expected to play an important role in increasing productivity, sustainability, and uniformity of future forests in the United States. For commercial use, SE technology must work with a variety of genetically diverse trees. Initiation in loblolly pine (LP; Pinus taeda L.), our main focus species, is often recalcitrant for desirable genotypes. Initiation of LP, slash pine (SP; Pinus elliottii), Douglas-fir (DF; Pseudotsuga menziesii), and Norway spruce (NS; Picea abies) were improved through the use of paclobutrazol, a gibberellin synthesis inhibitor. Paclobutrazol was effective at concentrations ranging from 0.25 mg/l to 3.0 mg/l (0.85-10.2 microM) and optimal in LP at 1.0 mg/l. Using control media (no paclobutrazol) and 0.33-1.0 mg/l paclobutrazol, initiation percentages in LP, SP, DF, and NS were improved from 37.7% to 44.2% (across experiments), 19.3% to 28.5%, 16.9% to 23.7%, and 38.8% to 48.5%, respectively. Other gibberellin inhibitors such as flurprimidol, chlormequat-Cl, and daminozide also caused statistically significant increases in LP initiation when added to the medium at concentrations of 0.34, 10.0, and 1.0 microM, respectively. No detrimental effects on subsequent embryo development were observed when 29 new initiations from medium without GA inhibitor and 28 new initiations from medium containing paclobutrazol were tracked through culture capture, liquid culture establishment, cotyledonary embryo development, and germination.

Culture Techniques↗