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Biomedical subjects

G Liu

Publications and source records attributed to G Liu.

At least 37 records · Page 2Linked to original sources
PubMed2005

Chinese medicinal herbs for acute bronchitis.

BACKGROUND: Acute bronchitis is one of the most common diagnoses made by primary-care physicians. It is traditionally treated with antibiotics, (although the evidence for their effectiveness is weak and modest at best), and other even less effective treatments. Chinese medicinal herbs have been also used as treatment. OBJECTIVES: This review aims to summarise the existing evidence on the comparative effectiveness and safety of Chinese medicinal herbs for treating uncomplicated acute bronchitis. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2005), which includes the Cochrane Acute Respiratory Infections Group's specialised register; The Chinese Cochrane Centre's Controlled Trials Register (up to December 2004); MEDLINE (1966 to March Week 1, 2005); EMBASE (1988 to December 2004); and the Chinese Biomedical Database (CBM) (1980 to December 2004). SELECTION CRITERIA: Randomised controlled trials comparing Chinese medicinal herbs with placebo, antibiotics or other Western medicines for the treatment of uncomplicated acute bronchitis. DATA COLLECTION AND ANALYSIS: At least two authors extracted data and assessed trial quality. MAIN RESULTS: Four trials reported the time to improvement of cough, fever, and rales associated with bronchitis and showed that patients treated with Chinese herbs had a shorter duration of signs and symptoms. Two trials reported the proportion of patients with improved signs and symptoms at follow up and showed that Chinese herbs were beneficial in terms of relief of signs and symptoms. Thirteen trials analysed the data on physician global assessment of improvement at follow up. Nine of thirteen trials showed that Chinese herbs were superior to routine treatment and the other four trials showed a similar effect to routine treatment. In general, Chinese herbs appeared beneficial. Only one trial reported on adverse effects during treatment. AUTHORS' CONCLUSIONS: There is insufficient quality data to recommend the routine use of Chinese herbs for acute bronchitis. The benefit found in this systematic review could be due to publication bias and study-design limitations of the individual studies. In addition, the safety of Chinese herbs is unknown due to the lack of toxicological evidence on these Chinese herbs, though adverse events are rarely reported. Chinese herbs should be used carefully.

Acute Disease↗
PubMed2005

Reaction of SO2 with AuCeO2(111): importance of O vacancies in the activation of gold.

Synchrotron-based high-resolution photoemission was used to study the adsorption and chemistry of SO(2) on AuCeO(2)(111) and AuO(x)CeO(2) surfaces. The heat of adsorption of the molecule on Au nanoparticles supported on stoichiometric CeO(2)(111) was 4-7 kcalmol larger than on Au(111). However, there was negligible dissociation of SO(2) on the AuCeO(2)(111) surfaces. The full decomposition of SO(2) was observed only after introducing O vacancies in the ceria support. AuO(x)CeO(2) surfaces were found to be much less chemically active than AuCeO(2)(111) or AuCeO(2-x)(111) surfaces. The active sites in {Au + AuO(x)}ceria catalysts should involve pure gold nanoparticles in contact with O vacancies.

Journal Article↗
PubMed2005

Conformation dependence of electronic structures of poly(ethylene oxide).

The electronic structure of pure poly(ethylene oxide) (PEO) for four different polymeric chain conformations has been studied by Hartree-Fock (HF) and density functional theory (DFT) through the analysis of their valence band photoelectron spectroscopy (VB-PES), X-ray emission spectroscopy (XES), and resonant inelastic X-ray scattering (RIXS). It is shown that the valence band of PEO presents specific conformation dependence, which can be used as a fingerprint of the polymeric structures. The calculated spectra have been compared with experimental results for PEO powder.

Electrochemistry↗
PubMed2005

Variation of long-lived free radicals responsible for the EPR native signal in bone of aged or diseased human females and ovariectomized adult rats.

The purpose of this study was to gain insights into the variations seen in the electron paramagnetic resonance (EPR) spectroscopy of the native signals of teeth and bones used for retrospective dosimetry measurements. We determined that changes occur in the long-lived free radicals responsible for the native signal of cortical bone in aging or diseased human females and aged ovariectomized rats. This was done by measuring the magnitude of the broad (BC) and narrow (NC) components of the native EPR signal of bone following chemical extraction, aging, crushing and thermal annealing. Bone from the upper midshaft of femora of young (17-34 years old, n=5) and elderly (70-92 years old, n=18) females was examined. The results showed that the elderly women had significantly higher BC than the younger women (P<0.01). A similar interpretation was made of the data from an aging female rat osteoporosis model. The results for the NC signals were similar. Finally, dramatic decreases in both NC and BC signals were seen in HIV positive and uncontrolled diabetic (one each) patients indicating the need for studying this signal for a broad spectrum of metabolic disorders. Experiments were performed which strongly indicate that iron liganded with organic molecules is the source of the BC signal. Finally, the accuracy achieved in this study indicates that resolving the dosimetric signal (g=2.0018) should be improved by subtraction of the deconvoluted NC and BC signals from the original spectrum.

Adolescent↗
PubMed2005

Adeno-associated virus type 4 (AAV4) targets ependyma and astrocytes in the subventricular zone and RMS.

The subventricular zone (SVZ) is one of the neurogenic niches in the adult mammalian brain. The SVZ is of interest for studies on neurogenesis and stem cell therapy. Here, we report specific transduction of ependyma and/or astrocytes by recombinant adeno-associated virus type 4 (AAV4) viral vectors. AAV4 vectors encoding beta-galactosidase or eGFP were injected into the lateral ventricles of neonatal and adult C57BL/6 mouse brains. In addition, SVZ injections were conducted on adult mice. AAV4 vectors show a characteristic transduction of the ependyma independent of delivery route. However, AAV4 virus injected into the SVZ targeted GFAP positive astrocytes forming the glial tube in the SVZ and rostral migratory stream (RMS). Our results introduce AAV4 as a new tool by which to manipulate glial cells in the RMS.

Animals↗
PubMed2005

Growth factor-induced signaling of the pancreatic epithelium.

Activated signaling proteins regulate diverse processes, including the differentiation of the pancreatic islet cells during ontogeny. Here we uncover the in vivo phosphorylation status of major growth factor-activated signaling proteins in normal adult mice and during pancreatic islet regeneration. We report elevated phospho-mitogen-activated protein kinase (phospho-MAPK), phospho-c-Jun-NH2-terminal kinase (phospho-JNK), and phospho-p38 MAPK expression during pancreatic regeneration. Immunoblotting experiments demonstrated elevated phosphorylation of p52 Src-homology/collagen (SHC) in the ductal network as well, substantiating the activation of this pathway. Furthermore, protein kinase B (PKB/Akt), a key signaling protein in the anti-apoptotic pathway, was phosphorylated to a greater extent in the ductal network from regenerating pancreas. We observed fibroblast growht factor (FGF)10 and platelet-derived growth factor (PDGF)AA expression in embryonic as well as regenerating adult pancreas. Epidermal growth factor (EGF) and PDGFAA stimulated MAPK and Akt phosphorylation, while FGF10 stimulated MAPK but not Akt phosphorylation in a time-dependent manner in freshly isolated cells from the adult ductal network. These data suggest that a heightened level of expression and stimulation of key signaling proteins underlie the expansion and differentiation processes that support pancreatic ontogeny and regeneration.

Animals↗
PubMed2004

Physical mapping of a rice lesion mimic gene, Spl1 , to a 70-kb segment of rice chromosome 12.

The rice lesion mimic mutant spotted leaf 1 ( spl1) was first identified in the rice ( Oryza sativa) cultivar Asahi in 1965. This mutant displayed spontaneous disease-like lesions in the absence of any pathogen, and was found to confer resistance to multiple isolates of rice blast. We employed a map-based cloning strategy to localize the Spl1 gene. A total of ten cleaved amplified polymorphic sequence (CAPS) markers linked to the Spl1 gene were identified and mapped to an 8.5-cM region on chromosome 12. A high-resolution genetic map was developed using these ten CAPS markers and a segregating population consisting of 3202 individuals. A BAC contig containing four BAC clones was constructed, and Spl1 was localized to a 423-kb region. Seven spl1 mutants were obtained from the IR64 deletion mutant collection, and molecular analysis using these mutants delimited the Spl1 gene to a 70-kb interval, covered by two BAC clones. These results provide the basis for cloning this gene, which is involved in cell death and disease resistance in rice.

Genetic Markers↗
PubMed2004

Rofecoxib: no effect on Alzheimer's disease in a 1-year, randomized, blinded, controlled study.

BACKGROUND: Inflammatory mechanisms have been implicated in the pathogenesis of Alzheimer's disease (AD) and may be mediated via the cyclo-oxygenase-2 enzyme. This study sought to evaluate the effect of rofecoxib, a nonsteroidal anti-inflammatory drug that selectively inhibits cyclo-oxygenase-2, in slowing the progression of dementia in patients with established AD. METHODS: A double-blinded, multicenter trial was conducted in which 692 patients with mild or moderate AD aged 50 years or older were randomly assigned to receive 25 mg rofecoxib or placebo daily for 12 months. The key efficacy measures were mean change from baseline at month 12 on the cognitive subscale of the AD Assessment Scale (ADAS-cog) and score on the Clinician's Interview Based Impression of Change with caregiver input (CIBIC+). RESULTS: Four hundred eighty-one patients (70%) completed assessments and remained on treatment at 12 months. No significant differences between treatments were found on the mean change from baseline error score for the ADAS-cog (rofecoxib = 4.84; placebo = 5.44; difference = -0.60) or mean score on the CIBIC+ (rofecoxib = 4.90; placebo = 4.87; difference = 0.03) over 12 months. This result persisted after adjusting for severity of dementia at baseline, presence of the APOE-epsilon4 allele, and donepezil use. Secondary analyses did not reveal any significant differences on any other measures. CONCLUSION: The failure of selective cyclo-oxygenase-2 inhibition to slow the progression of AD may indicate either that the disease process is too advanced to modify in patients with established dementia or that cyclo-oxygenase-2 does not play a significant role in the pathogenesis of the disorder.

Aged↗
PubMed2004

The linear accelerator mechanical and radiation isocentre assessment with an electronic portal imaging device (EPID).

Regular checks on the performance of radiotherapy treatment units are essential and a variety of protocols has been published. These protocols identify that the determination of isocentre must be accurate and unambiguous since both the localization of a radiation field on a patient and positioning aids are referenced to it. An EPID (BIS 710) with a combined light and radiation scintillation detector screen was used to assess mechanical and radiation isocentres for different collimator and gantry angles. Crosshair positions within light field images were determined from fitted Gaussian intensity profiles and then used to calculate the displacement of the mechanical isocentre. For comparison, the position of the crosshair was also recorded on a graph paper. The radiation field centre was first calculated from the set up geometry for given gantry/collimator angles and then compared with measured values to assess the displacement of the radiation isocentre. The radiation isocentre was also checked by locating a marker, positioned on the couch, on the EPID radiation images for different treatment couch angles. The mechanical and radiation isocentres were determined from the EPID light field and radiation images respectively with an accuracy of 0.3 mm using simple PC based programs. The study has demonstrated the feasibility of using the EPID to assess mechanical and radiation isocentres of a linear accelerator in a quick and efficient way with a higher degree of accuracy achieved as compared to more conventional methods, e.g. the star shot.

Australia↗
PubMed2004

An IMRT dose distribution study using commercial verification software.

The introduction of IMRT requires users to confirm that the isodose distributions and relative doses calculated by their planning system match the doses delivered by their linear accelerators. To this end the commercially available software, VeriSoft (PTW-Freiburg, Germany) was trialled to determine if the tools and functions it offered would be of benefit to this process. The CMS XiO (Computerized Medical System, St. Louis, MO) treatment planning system was used to generate IMRT plans that were delivered with an upgraded Elekta SL15 linac. Kodak EDR2 film sandwiched in RW3 solid water (PTW-Freiburg, Germany) was used to measure the IMRT fields delivered with 6 MV photons. The isodose and profiles measured with the film generally agreed to within +/- 3% or +/- 3 mm with the planned doses, in some regions (outside the field) the match fell to within +/- 5%. The isodose distributions of the planning system and the film could be compared on screen, allowing for electronic records of the comparison to be kept if desired. The features of this software would be of benefit to an IMRT QA program.

Benchmarking↗
PubMed2004

Induction of hypoxic root metabolism results from physical limitations in O2 bioavailability in microgravity.

Numerous spaceflight experiments have noted changes in the roots that are consistent with hypoxia in the root zone. These observations include general ultrastructure analysis and biochemical measurements to direct measurements of stress specific enzymes. In experiments that have monitored alcohol dehydrogenase (ADH), the data shows this hypoxically responsive gene is induced and is associated with increased ADH activity in microgravity. These changes in ADH could be induced either by spaceflight hypoxia resulting from inhibition of gravity mediated O2 transport, or by a non-specific stress response due to inhibition of gravisensing. We tested these hypotheses in a series of two experiments. The objective of the first experiment was to determine if physical changes in gravity-mediated O2 transport can be directly measured, while the second series of experiments tested whether disruption of gravisensing can induce a non-specific ADH response. To directly measure O2 bioavailability as a function of gravity, we designed a sensor that mimics metabolic oxygen consumption in the rhizosphere. Because of these criteria, the sensor is sensitive to any changes in root O2 bioavailability that may occur in microgravity. In a KC-135 experiment, the sensor was implanted in a moist granular clay media and exposed to microgravity during parabolic flight. The resulting data indicated that root O2 bioavailability decreased in phase with gravity. In experiments that tested for non-specific induction of ADH, we compared the response of transgenic Arabidopsis plants (ADH promoted GUS marker gene) exposed to clinostat, control, and waterlogged conditions. The plants were grown on agar slats in a growth chamber before being exposed to the experimental treatments. The plants were stained for GUS activity localization, and subjected to biochemical tests for ADH, and GUS enzyme activity. These tests showed that the waterlogging treatment induced significant increases in GUS and ADH enzyme activities, while the control and clinostat treatments showed no response. This work demonstrates: (1) the inhibition of gravity-driven convective transport can reduce the O2 bioavailability to the root tip, and (2) the perturbation of gravisensing by clinostat rotation does not induce a nonspecific stress response involving ADH. Together these experiments support the microgravity convection inhibition model for explaining changes in root metabolism during spaceflight.

Alcohol Dehydrogenase↗
PubMed2004

Avian pluripotent stem cells.

Pluripotent embryonic stem cells are undifferentiated cells capable of proliferation and self-renewal and have the capacity to differentiate into all somatic cell types and the germ line. They provide an in vitro model of early embryonic differentiation and are a useful means for targeted manipulation of the genome. Pluripotent stem cells in the chick have been derived from stage X blastoderms and 5.5 day gonadal primordial germ cells (PGCs). Blastoderm-derived embryonic stem cells (ESCs) have the capacity for in vitro differentiation into embryoid bodies and derivatives of the three primary germ layers. When grafted onto the chorioallantoic membrane, the ESCs formed a variety of differentiated cell types and attempted to organize into complex structures. In addition, when injected into the unincubated stage X blastoderm, the ESCs can be found in numerous somatic tissues and the germ line. The potential give rise to somatic and germ line chimeras is highly dependent upon the culture conditions and decreases with passage. Likewise, PGC-derived embryonic germ cells (EGCs) can give rise to simple embryoid bodies and can undergo some differentiation in vitro. Interestingly, chicken EG cells contribute to somatic lineages when injected into the stage X blastoderm, but only germ line chimeras have resulted from EGCs injected into the vasculature of the stage 16 embryo. To date, no lines of transgenic chickens have been generated using ESCs or EGCs. Nevertheless, progress towards the culture of avian pluripotent stem cells has been significant. In the future, the answers to fundamental questions regarding segregation of the avian germ line and the molecular basis of pluripotency should foster the full use of avian pluripotent stem cells.

Animals↗
PubMed2004

Expression of Smad2 and Smad4 in mouse uterus during the oestrous cycle and early pregnancy.

SMAD2 and SMAD4 are intracellular transducers of TGF-beta superfamily. In situ hybridization and semi-quantitative RT-PCR were employed to determine the temporal and spatial expression of Smad2 and Smad4 mRNA in mouse uterus during the oestrous cycle and early pregnancy. Smad2 mRNA was predominantly present in the luminal and glandular epithelium at dioestrus and prooestrus, while Smad4 expression was at a steady level in the luminal and glandular epithelium throughout the oestrous cycle. During pre-implantation period, Smad2 hybridization signals were accumulated in the luminal and glandular epithelium at a basal level; Smad4 mRNA appeared in the epithelium with a little variation in hybridization signal intensity. After implantation, on day 5 of pregnancy, Smad2 signals were localized to the subluminal stroma surrounding the implanting blastocyst, and Smad4 mRNA were accumulated in the decidua near the luminal epithelium. Both Smads were present in the decidua on days 6-7 with a switch from the mesometrial pole to the antimesometrial pole. RT-PCR results showed that both Smad2 and Smad4 mRNA levels were rising during peri-implantatation. The results suggest that Smad2 and Smad4 might be involved in the cycling changes of mouse uterus during the oestrous cycle and embryo implantation.

Animals↗
PubMed2004

Worker performance and ventilation in a call center: analyses of work performance data for registered nurses.

UNLABELLED: We investigated the relationship between ventilation rates and individual work performance in a call center, and controlled for other factors of the indoor environment. We randomized the position of the outdoor air control dampers, and measured ventilation rate, differential (indoor minus outdoor) carbon dioxide (DeltaCO(2)) concentration, supply air velocity, temperature, humidity, occupant density, degree of under-staffing, shift length, time of day, and time required to complete two different work performance tasks (talking with clients and post-talk wrap-up to process information). DeltaCO(2) concentrations ranged from 13 to 611 p.p.m. We used multivariable regression to model the association between the predictors and the responses. We found that agents performed talk tasks fastest when the ventilation rate was highest, but that the relationship between talk performance and ventilation was not strong or monotonic. We did not find a statistically significant association between wrap-up performance and ventilation rate. Agents were slower at the wrap-up task when the temperature was high (> 25.4 degrees C). Agents were slower at wrap-up during long shifts and when the call center was under-staffed. PRACTICAL IMPLICATIONS: The productivity benefits of ventilation rates that exceed common standards such as ASHRAE Standard 62 may be small (0-2%), and other factors may have a larger impact on productivity. Understaffing and long shifts should be avoided because both showed a negative impact on performance. In this study, high temperature had the largest statistically significant impact on productivity and was caused by occupants fighting over the thermostat setpoint. Care should be taken to avoid high temperatures in call centers. If occupants are allowed to adjust temperature setpoints, then the size and/or duration of the setpoint change should be restricted.

Humans↗
PubMed2004

Transcription factor binding and induced transcription alter chromosomal c-myc replicator activity.

The observation that transcriptionally active genes generally replicate early in S phase and observations of the interaction between transcription factors and replication proteins support the thesis that promoter elements may have a role in DNA replication. To test the relationship between transcription and replication we constructed HeLa cell lines in which inducible green fluorescent protein (GFP)-encoding genes replaced the proximal approximately 820-bp promoter region of the c-myc gene. Without the presence of an inducer, basal expression occurred from the GFP gene in either orientation and origin activity was restored to the mutant c-myc replicator. In contrast, replication initiation was repressed upon induction of transcription. When basal or induced transcription complexes were slowed by the presence of alpha-amanitin, origin activity depended on the orientation of the transcription unit. To test mechanistically whether basal transcription or transcription factor binding was sufficient for replication rescue by the uninduced GFP genes, a GAL4p binding cassette was used to replace all regulatory sequences within approximately 1,400 bp 5' to the c-myc gene. In these cells, expression of a CREB-GAL4 fusion protein restored replication origin activity. These results suggest that transcription factor binding can enhance replication origin activity and that high levels of expression or the persistence of transcription complexes can repress it.

Amanitins↗
PubMed2003

fMRI of triggerable aurae in musicogenic epilepsy.

The authors studied a patient with musicogenic epilepsy triggered by one specific musical piece using 3D PRESTO fMRI. During epileptic aurae initiated by the stimulus, signal increases were found in the left anterior temporal lobe, correlating with ictal EEG and SPECT showing a left anterior temporal focus, and the right gyrus rectus. Because fMRI indicated a cascade of recruitment of the ventral frontal lobes by epileptogenic music, left anterior temporal lobe activity could be secondary to a right gyrus rectus focus, possibly triggered by emotional processing of music.

Acoustic Stimulation↗
PubMed2003

Adventitious shoot regeneration from in vitro cultured leaves of London plane tree (Platanus acerifolia Willd.).

Adventitious shoots were successfully regenerated from leaf explants of in vitro cultures of Platanus acerifolia Willd. The leaves of three clones (genotypes), designated as PH1, PH2 and PC, respectively, were wounded by three to four transverse cuts through the midvein and cultured on 26 media based on Murashige and Skoog (MS) basal medium, containing different concentrations of 6-benzylaminopurine (BAP) in combination with different concentrations of indole-3-butyric acid (IBA). The highest regeneration rate (>90%) and the largest number of shoot clumps per regenerating leaf (>4 shoot clumps/explant) were obtained with leaves of genotype PH2 cultured on MS basal medium supplemented with 17.76 microM BAP and 4.92 microM IBA. The other two genotypes, PH1 and PC, showed very low capability of shoot regeneration (<10%) on all the media tested. Shoots on leaf explants originated mainly from callus that developed around the cut end of petioles and along the cuts across the midvein. The regenerated shoots were micropropagated, rooted and transplanted to the soil successfully.

Adenine↗