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Biomedical subjects

Q Shen

Publications and source records attributed to Q Shen.

At least 19 recordsLinked to original sources
PubMed2007

Establishment of a stroke unit in a district hospital: review of experience.

BACKGROUND: The experience and outcomes of co-locating acute stroke and stroke rehabilitation care in a district hospital were reviewed. METHOD: Information for patients admitted to Blacktown and Mt Druitt Hospitals before and after setting up an acute stroke unit (SU) (12 months data for each period), including mortality and length of stay (LOS) at the hospital were obtained from various sources, including the diagnosis-related group and subacute and non-acute casemix databases. RESULTS: There was a significant reduction of mortality (18 vs 10%; P = 0.01) and reduced total LOS (46 vs 39 days; P = 0.01) with similar functional outcomes in the post-SU period. Fifty per cent of patients were unable to access the acute SU. Patients admitted into the SU had lower mortality (5 vs 14%; P = 0.01) and were also discharged from hospital earlier (35 vs 54 days; P = 0.01) than patients admitted into general wards during the post-SU period. Thirty-four per cent of patients received rehabilitation within the rehabilitation facility in the post-SU period compared with 19% in the pre-SU period. CONCLUSION: The Blacktown experience showed the feasibility of establishing a co-located SU within rehabilitation facility with good outcomes as illustrated by the significant reduction in the stroke mortality, a reduction in the total LOS and an increase in the number of patients receiving rehabilitation post-stroke.

Hospital Departments↗
PubMed2006

Effect of ammonium and nitrate nutrition on some physiological processes in higher plants - growth, photosynthesis, photorespiration, and water relations.

Ammonium and nitrate as different forms of nitrogen nutrients impact differently on some physiological and biochemical processes in higher plants. Compared to nitrate, ammonium results in small root and small leaf area, which may contribute to a low carbon gain, and an inhibition on growth. On the other hand, due to (photo)energy saving, a higher CO (2) assimilation rate per leaf area was observed frequently in plants supplied with ammonium than in those supplied with nitrate. These results were dependent not only on higher Rubisco content and/or activity, but also on RuBP regeneration rate. The difference in morphology such as chloroplast volume and specific leaf weight might be the reason why the CO (2) concentration in the carboxylation site and hence the photorespiration rate differs in plants supplied with the two nitrogen forms. The effect of nitrogen form on water uptake and transportation in plants is dependent both on leaf area or shoot parameter, and on the root activity (i.e., root hydraulic conductivity, aquaporin activity).

Biological Transport↗
PubMed2006

Determination of the mechanism for resonant scattering in LaMnO3.

The resonant multiple Bragg x-ray diffraction is used to study the forbidden (104) reflection in LaMnO3. Using the interference between the three-beam scattering and resonant scattering we can determine the phase of the resonant scattering. This phase is shown to be consistent with a model in which the resonant scattering is caused by the influence of the Mn-O bond length distortion rather than directly by the orbital ordering on the Mn 4p band structure.

Journal Article↗
PubMed2006

Identifying the determinants of 1-year post-stroke outcomes in elderly patients.

OBJECTIVES: To examine 12-month outcomes and develop predictive models for outcomes in elderly stroke patients. METHODS: Prospective study of 186 consecutive acute stroke patients aged > or = 65 years admitted to a local hospital between March 2002 and March 2003. Outcome measurements included mortality, functional independence measure (FIM) score and nursing home placement. Two predictive models, using multiple logistic regression analysis, were developed to identify the factors associated with (i) mortality, and (ii) being alive and independent (defined as mean FIM score > or = 90) at 12 months. RESULTS: One hundred and seventy two (92%) patients were followed up at 12 months post-stroke. Mortality rate was 31%, and was significantly higher in nursing home vs non-nursing home origin patients (68% [15/22] vs 25% [38/150]). Nursing home placement for non-nursing home origin survivors was 28% (31/112). Age > or = 85 years was associated with higher mortality (odds ratio = 5.3, 95% confidence interval = 1.8-15, P < 0.01) and lower FIM for patients living at home pre-stroke. Predictive models showed that age, not living at home pre-stroke, pre-stroke FIM < 108, inability to walk on admission, dysphasia, visual field loss and haemorrhagic stroke were associated with worse outcome. CONCLUSIONS: Predictive models--by developing new strategies to improve outcomes through identifying treatable predictive factors--may be clinically useful in elderly stroke patients.

Activities of Daily Living↗
PubMed2006

Stroke risk factor, pattern and outcome in patients with cancer.

OBJECTIVE: To investigate risk factors, stroke pattern and outcome in stroke patients with cancer. METHODS: A retrospective review of all stroke patients with cancer (n = 69) admitted to Bankstown-Lidcombe Hospital, Sydney, Australia, between January 1999 and December 2004 was conducted, and comparison made to age- and gender-matched non-cancer stroke patients admitted to the same hospital during the same period. RESULTS: Vascular risk factors did not significantly differ between cancer and non-cancer groups. There was a trend towards greater risk of intracerebral haemorrhage in the cancer group vs the non-cancer group. Previous deep vein thrombosis was more common, and prothrombin time and activated partial thromboplastin time were prolonged in the cancer group vs the non-cancer group. More patients died in hospital in the cancer group vs the non-cancer group. CONCLUSIONS: Coagulation disorders are more likely to be seen in stroke patients with cancer, and patients with cancer have a higher in-hospital post-stroke mortality.

Aged↗
PubMed2005

Interfacial interaction of tartaric acid with hydroxyapatite and enamel.

The purpose of this study was to investigate the interfacial interaction of tartaric acid with hydroxyapatite and enamel. Hydroxyapatite particles were mixed with 15% (w/v) alcohol-aqueous (1:1) solution of tartaric acid for 72 h. After the mixture, the filtrate was separated from the solid. The filtrate, the solid, hydroxyapatite, and tartaric acid were dried for FTIR and XRD analysis. Enamel disks etched with tartaric acid for 60 s were analyzed by attenuated total reflectance (ATR). Enamel disks etched with 15% tartaric acid for 15, 30, 60, 120 s were analyzed by SEM. FTIR spectra showed carboxylate in the solid and in subtraction spectra. ATR spectra revealed carboxylate on the enamel surfaces. XRD data indicated the formation of calcium tartrate and calcium hydrogen phosphate after the reaction of tartaric acid with hydroxyapatite. SEM observations revealed typical decalcification of the periphery of the enamel rods due tartaric acid etching. It is concluded that tartaric acid can decalcify and chemisorb onto HA simultaneously, hence, tartaric acid could be used as etchant and ingredient of self-etching primers in adhesive dentistry.

Acid Etching, Dental↗
PubMed2005

Histological precursors of oesophageal squamous cell carcinoma: results from a 13 year prospective follow up study in a high risk population.

BACKGROUND: Oesophageal squamous cell carcinoma (OSCC) has a very poor prognosis, which is largely due to late diagnosis. Successful early detection strategies will require identification of clinically relevant precursor lesions that can be targets for screening and treatment. AIMS: To identify the clinically relevant histological precursors of OSCC. SUBJECTS: A cohort of 682 endoscoped patients from a high risk rural population in Linxian, China. METHODS: Subjects were endoscoped and biopsied at baseline and followed for 13.5 years. We estimated the relative risk of developing OSCC for each of the initial histological diagnoses using Cox proportional hazards regression models. RESULTS: A total of 114 (16.7%) patients developed OSCC during the follow up period. After adjusting for potential confounding factors, relative risks (95% confidence intervals) for incidence of this tumour, by initial histological diagnosis, were: normal 1.0 (reference), oesophagitis 0.8 (0.2-3.2), basal cell hyperplasia 1.9 (0.8-4.5), mild dysplasia 2.9 (1.6-5.2), moderate dysplasia 9.8 (5.3-18.3), severe dysplasia 28.3 (15.3-52.3), and carcinoma in situ 34.4 (16.6-71.4). CONCLUSIONS: In this study, squamous dysplasia and carcinoma in situ were the only histological lesions associated with a significantly increased risk of developing OSCC within 13.5 years after endoscopy. There was no evidence that oesophagitis predisposed to this tumour. Increasing grades of dysplasia were strongly associated with increasing risk, indicating that the histological grading was clinically meaningful. The follow up experience of severe dysplasia and carcinoma in situ was equivalent, suggesting that this distinction is not clinically relevant. Documenting these precursor lesions of OSCC should assist in the development of effective prevention, early detection, and treatment strategies for this disease.

Adult↗
PubMed2005

Role of urinary screening programmes in children in the prevention of chronic kidney disease.

INTRODUCTION: This article reviews published literature on the usefulness of population-based urinary screening in the Asian paediatric population. METHODS: Articles were found in the Medline database using the key words "paediatrics", "urine screening", "proteinuria", "haematuria" and "population". The Asian countries which had carried out population-based urinary screening of the paediatric population included Taiwan, Japan and Korea. One study was found on urinary screening in a select population in Malaysia. Preliminary results of the urinary screening of school children in Singapore are presented and compared with the results found in the above-mentioned countries. RESULTS: Overall, the proportion of children found to have urinary abnormalities ranged from less than 0.1% of the population screened to almost 50% of a select cohort referred from the screening programmes for the evaluation of urinary abnormalities. In the pilot Singapore school screening programme, the prevalence of clinically significant proteinuria was 1.25 per 1000 children screened. Multivariate analysis showed that low body weight was associated with a 1.8-fold greater risk for proteinuria. The major cause of haematuria and proteinuria in those studies where renal biopsies were performed was glomerulonephritis. The Taiwanese experience also showed a reduction in the incidence of end-stage renal failure diagnosed in children after the onset of urine screening. CONCLUSION: These studies showed that urinary screening programmes in school children allow the early detection of disease. The cost-benefit ratio for specific populations should be determined before the implementation of such programmes.

Asia↗
PubMed2004

Molecular structure of 2,2,4,4,6,6-hexamethyl-1,3,5-trimethylenecyclohexane as determined by gas-phase electron diffraction.

The molecular structure of 2,2,4,4,6,6-hexamethyl-1,3,5-trimethylenecyclohexane has been determined in the gas phase at a nozzle tip temperature of 340 K. The electron diffraction data were found to be consistent with a model where the cyclohexane ring adopts a distorted twist-boat conformation. The averaged geometrical parameters (r(g) and 90 degree angle (alpha)) obtained from least squares analysis are r(C=C) = 1.346(4) A, r(C-C)(ring) = 1.537(1) A, r(C-C)(Me) = 1.543(1) A, 90 degree angle C(6)C(1)C(2) = 117.5(11) degrees, 90 degree angle C(1)C(2)C(3) = 113.1(12) degrees, and 90 degree angle MeCMe = 108.2(13) degrees. The experimental results are consistent with the results from HF/6-311G(d) and MP2/6-311G(d) calculations where the distorted twist-boat form is found to be lower in energy than the chair form by 9.85 and 10.7 kcal/mol, respectively.

Journal Article↗
PubMed2004

Retinoid X receptors: X-ploring their (patho)physiological functions.

Retinoid X receptor (RXR) belongs to a family of ligand-activated transcription factors that regulate many aspects of metazoan life. A class of nuclear receptors requires RXR as heterodimerization partner for their function. This places RXR in the crossroad of multiple distinct biological pathways. This and the fact that the debate on the endogenous ligand requirement for RXR is not yet settled make RXR still an enigmatic transcription factor. Here, we review some of the biology of RXR. We place RXR into the evolution of nuclear receptors, review structural details and ligands of the receptor. Then processes regulated by RXR are discussed focusing on the developmental roles deduced from studies on knockout animals and metabolic roles in diseases such as diabetes and atherosclerosis deduced from pharmacological studies. Finally, aspects of RXR's involvement in myeloid differentiation and apoptosis are summarized along with issues on RXR's suitability as a therapeutic target.

Animals↗
PubMed2003

Energy-recovery linac project at Cornell University.

There is considerable interest in using superconducting electron linacs with energy recovery as synchrotron radiation sources. Such energy recovery linacs (ERLs) would open new regimes of X-ray science because they are capable of producing ultra-brilliant X-ray beams [>5 x 10(22) photons s(-1) (0.1% bandwidth)(-1) mm(-2) mrad(-2) at 10 keV], maintaining a very small source size ( approximately 3 micro m r.m.s.) suitable for micro X-ray beams, and making very intense fast ( approximately 100 fs) X-ray pulses. Each of these characteristics would permit the execution of experiments that are not feasible with existing synchrotron sources. Many technical issues must be satisfactorily resolved before the potential of a full-scale ERL can be realised, including the generation of high average current (10 to 100 mA), high-brightness electron beams (0.015 to 0.15 nm rad emittances, respectively); acceleration of these beams to energies of 5-7 GeV without unacceptable emittance degradation; stable and efficient operation of superconducting linear accelerators at very high gradients etc. Cornell University, in collaboration with Jefferson Laboratory, has proposed to resolve these issues by the construction of a 100 MeV, 100 mA prototype ERL. The intention is to then utilize the information that is learned from the prototype to propose the construction of a full-scale ERL light source.

Journal Article↗
PubMed2003

Interplay between anisotropic strain relaxation and uniaxial interface magnetic anisotropy in epitaxial Fe films on (001) GaAs.

Grazing incidence x-ray diffraction study of Fe epitaxial ultrathin films (1.5-13 nm) on GaAs (001) reveals an anisotropy of both domain shape and strain, with [110] and [1-10] as the principal directions. It is shown that the observed thickness-dependent strain anisotropy, together with a uniaxial interface term, can provide an unambiguous explanation to the usual in-plane magnetic anisotropy and its thickness dependence observed in this magnetic thin-film system.

Journal Article↗
PubMed2003

Antigenic profiles of disseminated breast tumour cells and microenvironment in bone marrow.

AIMS: Thirty per cent of breast cancer patients with axillary lymph node negative at primary surgery will relapse within 10 years. This may be caused by disseminated tumour cells from the primary tumour. This study report the phenotypic profiles of disseminated tumour cells and microenvironmental characteristics in bone marrow of breast cancer. METHODS: We detected the biologic markers on the disseminated tumour cells with immunocytochemical staining, analysed the immunological changes through flow-cytometry, and investigated the u- PA activity in the plasma of bone marrow. RESULTS: With the immunocytochemical staining of EMA and CK19, we detected micrometastasis in thirty out of 72 (41.67%) breast cancer patients. Compared with the primary tumours, disseminated tumour cells expressed low protein cyclin D1, P53, Ki-67, EGFR, and high protein P21. The percentage of memory CD4+ T cells was significantly higher in the micrometastasis-positive group than in the micrometastasis-negative group. Tumour size and axillary lymph node status were found to be significantly correlated with the u- PA activity level. CONCLUSIONS: Immunophenotypic profiles of disseminated tumour cells could be measured by immunocytochemical staining and microenvironment can be analysed by flow cytometry.

Adult↗
PubMed2002

Effects of genotypes of maitake (Grifola frondosa) on biological efficiency, quality and crop cycle time.

Twenty-three genotypes of maitake (Grifola frondosa) from Asia, North America and Europe were compared for biological efficiency (BE), quality and crop cycle time. Significant differences among lines were found for BE and crop cycle time when mushrooms were produced on nutrient-supplemented (15% millet, 10% wheat bran and 0.2% gypsum) oak sawdust substrate. Four isolates (WC828, M036, M037, and M040) were found to have the most consistent and highest BEs (38.5%, 39.5%, 35.8%, and 38.9%, respectively) and quality ratings (1.2, 1.3, 1.4, and 1.2, respectively, where I is highest quality and 4 is lowest quality). A commercial line (M039) used in China had the shortest crop cycle time (8 weeks). Lines deemed to have the best commercial potential were of Asian origin.

Agaricales↗
PubMed2002

Functional nicotinic acetylcholine receptor expression on stem and progenitor cells of the early embryonic nervous system.

Although the adult brain contains nicotinic acetylcholine (ACh) receptors vital to cortical function, little is known about the assembly of embryonic receptor subunits into functional receptors or their role in fetal brain development. We now report the first evidence of functional nicotinic ACh receptors on stem and progenitor cells of fetal mouse cerebral cortex as early as embryonic day 10.

Animals↗
PubMed2001

Functional nicotinic acetylcholine receptor expression in stem and progenitor cells of the early embryonic mouse cerebral cortex.

The adult cerebral cortex contains nicotinic acetylcholine (ACh) receptors vital to cortical function. However, little is known about the assembly of embryonic nicotinic receptor subunits into functional receptors or whether they play an active role in cortical development. We now report evidence of functional nicotinic acetylcholine receptor channels in fetal mouse cerebral cortex as early as embryonic day 10 (E10), when the cortex consists of dividing stem and progenitor cells. Patch-clamp electrophysiological measurements indicate that nicotine and ACh evoke sizable inward currents characteristic of nicotinic receptors, that are strongly rectifying with a reversal potential near 0 mV. Three different nicotinic agonists, ACh, nicotine, and dimethylphenylpiperazinium, evoked cytosolic Ca(2+) signals. Agonist-evoked Ca(2+) signals and electrophysiological responses were found in greater than 70% of all E10-E11 cells tested and were blocked by nicotinic receptor antagonists. The Ca(2+) response to nicotinic agonists was markedly prolonged in cells from early embryonic stages relative to later stages of development. alpha3, alpha4, and alpha7 receptor subunit proteins were detected immunocytochemically in cortical cells from E10 to birth. The incidence of each subunit declined with embryonic age, suggesting a role in early development. We discuss the possible function of nicotinic receptors in early cortical development and their role as a target for nicotine in the developmental pathologies associated with the fetal tobacco syndrome.

Acetylcholine↗
PubMed2001

Molecular structure and conformation of cyclopropylbenzene as determined by ab initio molecular orbital calculations, pulsed-jet fourier transform microwave spectroscopic, and gas-phase electron diffraction investigations.

Ab initio computational, microwave spectroscopic, and electron diffraction techniques have been used to study the gas-phase structure of cyclopropylbenzene. Theoretical calculations at the HF, B3LYP, and MP2 levels for basis sets 6-31G(d) and 6-311G(d) have been carried out. Both MP2 and B3LYP calculations showed the bisected form to be lower in energy (245/157 and 660/985 cal mol(-1), respectively, for basis sets 6-311G(d)/6-31G(d)). Rotational constants for the bisected form of the parent and eight singly substituted (13)C isotopic species were obtained. The selection rules of the observed rotational transitions and the facts that eight (rather than six) singly substituted (13)C isotopers are observed and assigned and that seven of the compound's nine carbon atoms lie in the molecule's symmetry plane required the molecule to exist in the bisected conformation. No transition from the perpendicular form was observed in the pulsed-jet microwave experiment. Gas-phase electron diffraction data were collected at a nozzle-tip temperature of 265 K. Least squares analyses were carried out using ED data alone and with the inclusion of microwave rotational constants. The principal structural results (r(g) and angle(alpha)) obtained from the combined ED/MW least-squares analysis are r(C-H)(av) = 1.093(6) A, r(C(7)-C(8))(v) = 1.514(20) A, r(C(8)-C(9))(d) = 1.507(26) A, r(C(7)-C(1)) = 1.520(25) A, r(C-C)(Ph) = 1.395(1) A, angleC(1)C(7)C(8) = 119.6(17) degrees, angleC(2)C(1)C(7) = 122.5(25) degrees, angleC(1)C(2)C(3) = 120.9(35) degrees, angleHC(8)C(9) = 116.7(20) degrees, angleHCC(Ph) = 120.0 degrees (assumed).

Journal Article↗