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Biomedical subjects

W Qian

Publications and source records attributed to W Qian.

At least 55 records · Page 3Linked to original sources
PubMed2000

Cataract formation by a semiquinone metabolite of acetaminophen in mice: possible involvement of Ca(2+)and calpain activation.

Acetaminophen, an analgesic/antipyretic, is metabolized by hepatic cytochrome P450 to N -acetyl- p -benzoquinone imine (NAPQI), which is transported by blood circulation to the eye and induces anterior cortical cataract in mice. In this study we injected NAPQI into the anterior chamber of mouse eye and investigated time-dependent cellular responses in the lens. After a lag period of about 2 hr following NAPQI injection, lens opacification as determined by measurement of light scattering by the lens became evident and progressively increased thereafter. There was no difference in the profile of opacity development between a P450-inducer responsive mouse strain and a non-responsive strain. During the lag period, a marked increase in free intracellular Ca(2+)in the lens epithelium was observed at 1 hr by confocal fluorescence microscopy with a Ca(2+)probe. Concurrent with the free Ca(2+)increase, there was a 300% rise in the activity of the non-lysosomal neutral protease calpain in the lens at 1 hr after NAPQI injection. Evidence indicated degradation of vimentin in the lens in which calpain activity was enhanced. Co-injection of calpain inhibitors (N-Ac-Leu-Leu-norleucinol and N-Ac-Leu-Leu-methioninal) with NAPQI protected animals completely from cataract development, although a rise in free intracellular Ca(2+)in the lens epithelium was still observed. Lenses from the protected mice did not exhibit enhanced calpain activity. These results suggest the following sequence of events as a possible mechanism of NAPQI-induced cataract. NAPQI introduced in the anterior chamber of the eye enters the lens epithelial cells and disturbs Ca(2+)homeostasis with a resultant rise in free intracellular Ca(2+)which in turn activates calpain in the epithelium. The neutral protease then degrades cellular proteins (e.g. cytoskeletal proteins) and initiates anterior cortical cataract formation.

Acetaminophen↗
PubMed2000

Where do developing World clinicians obtain evidence for practice: a case study on pneumonia.

There are few data on the practice of evidence based medicine in the developing world, nor on the actual sources of evidence that clinicians use in practice. To test the hypothesis that there was variation between and within developing countries in the proposed management of a patient with hospital acquired pneumonia, and that part of the variation can be explained by the sources of evidence used. Questionnaire responses to hypothetical case history. Investigators from 6 centres within the International Clinical Epidemiology Network (INCLEN) in China, Thailand, India, Egypt, and Kenya. Doctors chosen to represent primary and secondary hospital practice in the regions of the study centres. Investigations and initial treatments which would be ordered for a hypothetical 60-year-old woman who develops pneumonia 5 days after hospital admission, whether local data on antibiotic sensitivities are available and where information would be obtained to guide management. Chest x-ray and sputum gram stain/culture were consistently the most commonly ordered investigations, there being much greater variation in the initial treatment choices with either penicillin, a third-generation cephalosporin or aminoglycoside being the most popular choice. Textbooks were the commonest form of information source, and access to a library, textbooks and journals were statistically significantly associated with appropriate choice of investigations, but not treatment. Access to local antibiotic sensitivities was associated with appropriate initial treatment choice. Improving access to information in the literature and to local data may increase the practice of evidence-based medicine in the developing world.

Cross Infection↗
PubMed2000

Angular change in backscattering of light from the human lens with nuclear cataract.

PURPOSE: To determine how many meridians are needed to optimise detection of lens nuclear opacities in Scheimpflug photography utilising the Nidek EAS-1000 system. METHODS: Ten eyes with nuclear cataract from 10 patients (age 53-83 years) were selected in this study. For each eye, the lens was imaged with the Nidek EAS-1000 system at the 0 degree, 30 degrees, 60 degrees, 90 degrees, 120 degrees and 150 degrees meridians, respectively. The intensity of the backscattering of light within a common lens nuclear area on the lens image was measured. In addition an aqueous suspension of polystyrene spheres was employed as a standard to evaluate the possible angular change caused by the camera system. Analysis of variance and the polynomial regression was used for data analysis. RESULTS: The intensity of the backscattered light differs significantly among meridians. The highest intensity is found at the 90 degrees meridian. The intensity decreases towards the nasal and temporal side. There is also an angular variation caused by the camera system. CONCLUSIONS: There is a regular change in the backscattered light documented by the Nidek EAS-1000 system. It is sufficient to take one meridian to estimate the lens nuclear cataract. The variation in the backscattered light at different angles is caused partly by the variation of the camera.

Aged↗
PubMed2000

Acetaminophen produces cataract in DBA2 mice by Ah receptor-independent induction of CYP1A2.

The metabolic transformation of acetaminophen to N-acetyl-p-benzoquinone imine by cytochrome P450 enzymes (e.g., cytochrome P450 1A2) is a prerequisite for acetaminophen-induced cataract formation in mice. Aromatic hydrocarbons, such as beta-naphthoflavone, induce cytochrome P450 1A2 in C57BL6 mice via the mediation of the aromatic hydrocarbon receptor and render the animals susceptible to cataract formation by acetaminophen administration but not in DBA2 mice which do not respond to cytochrome P450 1A2 induction by these compounds. Polycyclic hydrocarbons, such as acenaphthylene, were recently found to induce cytochrome P450 1A2 gene expression in young DBA2 mice by aromatic hydrocarbon receptor-independent pathways. In this work, we investigated whether enhanced metabolism of acetaminophen to N-acetyl-p-benzoquinone by cytochrome P450 1A2 induction by acenaphthylene could produce cataract in young DBA2 mice. Fifteen-day-old DBA2 mice were pretreated with two intraperitoneal injections of acenaphthylene and, 24 hr later, with one injection of acetaminophen. In most mice, cataract developed 18-24 hr after acenaphthylene injection. Acenaphthylene treatment of young DBA2 mice resulted in a 2-fold increase in cytochrome P450 1A2-dependent methoxyresorufin O-demethylase activity in the liver. These results support the hypothesis that the aromatic hydrocarbon receptor-independent induction of cytochrome P450 1A2 enzyme leads to accumulation of sufficient N-acetyl-p-benzoquinone in the liver and cataract development in the eye.

Acenaphthenes↗
PubMed2000

Hypoxia depresses nitric oxide output in the human nasal airways.

OBJECTIVES: The role of oxygen in the nasal air on nasal nitric oxide (NO) output was studied in 13 adult volunteers. METHODS: Nasal NO was measured while air containing oxygen (0%-100% in nitrogen) was aspirated through the nasal airway before and after the topical application of xylometazoline. RESULTS: The mean nasal NO output of the untreated nose was 507.8 +/- 161.9 nL/min (mean +/- SD) when 21% oxygen was aspirated through the nasal cavities in series and remained unaltered by 100% O2 (P = .79). Below 10% oxygen the reduction in nasal NO output correlated positively and significantly with the decrease in oxygen concentration (r2 = 0.14). NO output was 245.2 +/- 153.4 nL/min at 0% oxygen, a significant decline from 21% oxygen (P < .0001). Nasal vasoconstriction induced by xylometazoline and alterations in the blood oxygen content by a maximal breath-holding or breathing 100% oxygen did not alter nasal NO in hypoxia (P = .41). CONCLUSIONS: Nasal NO output is markedly depressed in hypoxia and is oxygen dependent at concentrations of less than 10%. Approximately 50% of nasally generated NO is produced from oxygen in nasal air or regulated by it.

Administration, Topical↗
PubMed2000

3 year simvastatin treatment and lens nuclear back scattering.

AIM: To determine if 3 year treatment of hypercholesterolaemia with simvastatin causes an increase of lens nuclear back scattering. METHODS: 160 patients with hypercholesterolaemia in the Scandinavian Simvastatin Survival Study (4S) were followed for 3 years. Half (80) of the patients took simvastatin and half (80) received placebo. The lens was photographed with a Topcon SL-45 slit lamp camera at the beginning and at 1 year intervals. A common lens nuclear area was used for measuring lens nuclear back scattering. RESULTS: Nuclear back scattering increased with age and there was more pronounced scattering in women than in men. Lens nuclear back scattering did not differ significantly between the simvastatin and placebo groups, but the power was low (0.2). Lens nuclear back scattering increased during the study period independently of baseline back scattering, age, and sex for both groups. CONCLUSION: Although no significant difference was found between the simvastatin and placebo groups, the currently available data are insufficient for exclusion of the possibility that taking simvastatin during a 3 year period increases nuclear back scattering. However, a possible minor increase of nuclear back scattering is clinically irrelevant considering known beneficial effects of simvastatin on coronary heart disease.

Adult↗
PubMed2000

Unilateral nasal nitric oxide measurement after nasal surgery.

This study was designed to validate and standardize a method for unilateral nasal nitric oxide (NO) measurement. Fourteen healthy volunteers and 11 patients who had undergone unilateral medial maxillectomy were enrolled. Nasal NO was measured unilaterally by means of a dual pump system, and bilateral nasal NO was measured by aspirating air through the nasal airway in series. The median unilateral NO output was 195 nL/min on the surgical side and 291 nL/min on the contralateral, surgically untreated side (p = .006). The NO output was not significantly different between nostrils in the control group (p = .82). With the bilateral technique, there was no significant difference between the surgery group and the healthy-subjects group (p = .72). The unilateral nasal NO technique is sensitive in determining unilateral differences in nasal NO production. The NO outputs from the nostrils were similar in normal subjects regardless of the nasal cycle, but were significantly lower on the operated side in the unilateral nasal surgery group.

Adult↗
PubMed2000

Improving survival without reducing quality of life in small-cell lung cancer patients by increasing the dose-intensity of chemotherapy with granulocyte colony-stimulating factor support: results of a British Medical Research Council Multicenter Randomized Trial. Medical Research Council Lung Cancer Working Party.

PURPOSE: The treatment of small-cell lung cancer patients with good performance status aims to improve survival. Dose-intensification could be a way to achieve improved survival but can be limited by neutropenia and thrombocytopenia. Preliminary, nonrandomized feasibility studies showed that doxorubicin, cyclophosphamide, and etoposide (ACE) could be given every 2 (instead of the usual 3) weeks with granulocyte colony-stimulating factor (G-CSF) (lenograstim; Chugai-Rh¿one-Poulenc, Tokyo, Japan) support. The present multicenter randomized trial was designed to examine whether such dose-intensification improves survival while maintaining acceptable toxicity levels. PATIENTS AND METHODS: All patients were randomized to receive six cycles of ACE either every 3 weeks (control [C] group) or every 2 weeks with G-CSF (G group). The standard dose-intensity of ACE was increased by 50% in group G. RESULTS: Four hundred and three patients (G group: n = 201; C group: n = 202) were randomized. The received dose-intensity was 34% higher in the G group than in the C group. Complete response rates were 40% for the G group and 28% for the C group (P =.02), and overall rates were 78% for the G group and 79% for the C group. Survival was longer in the G group (hazard ratio = 0.80; 95% confidence interval, 0.65 to 0.99; P =.04), survival rates for the G and C groups being 47% and 39% at 12 months and 13% and 8% at 24 months, respectively. Metastasis-free survival, nonhematologic toxicity, and quality of life were similar in the two groups. In the G group, there was less neutropenia but more thrombocytopenia and more frequent blood and platelet transfusions. CONCLUSION: Increasing the dose-intensity of ACE with G-CSF support improved survival while maintaining acceptable toxicity.

Adult↗
PubMed2000

Localized exocytosis detected by spatially resolved amperometry in single pancreatic beta-cells.

Spatially resolved measurements of exocytosis in pancreatic beta-cells were made using amperometry with 1-microm radius electrodes. These measurements revealed that certain portions of a cell actively undergo exocytosis following stimulation with depolarizing agents, but other regions are inactive. The amperometric measurements were compared to measurements made with the membrane indicator dye, FM1-43, which showed uneven increases in fluorescence around the surface of the cell, with amperometric secretion being detected only at the brightest regions. In some instances, a large number of exocytotic events were detected from one electrode position. The number of events was larger than what would be expected based on the number of vesicles that could fit under an electrode of the dimensions used. These results suggest a mechanism of vesicle traffic that allows multiple fusions at a small membrane area.

Animals↗
PubMed2000

Polyoma virus middle T and small t antigens cooperate to antagonize p53-induced cell cycle arrest and apoptosis.

Wild-type p53 triggers two distinct biological responses, cell cycle arrest and apoptosis. Several small DNA tumor viruses encode proteins that bind p53 and thus block the function of p53. This probably reflects the need of these viruses to prevent p53-induced cell cycle arrest and apoptosis to allow viral DNA replication. Unlike SV40 large T, polyoma virus large T does not bind p53, and it is still unclear how polyoma virus blocks p53 function. To address this question, we transfected polyoma virus middle T or small t alone or middle T and small t together into J3D mouse T-lymphoma cells carrying temperature-sensitive p53 (ts p53). Induction of wild-type p53 by temperature shift to 32 degrees C triggered both G1 cell cycle arrest and apoptosis in parental J3D-ts p53 cells. In contrast, J3D-ts p53 cells coexpressing middle T and small t showed only a weak G1 cell cycle arrest response after induction of wild-type p53 at 32 degrees C. Fluorescence-activated cell sorter analysis revealed that nearly half of the middle T-expressing cells, 30% of the small t-expressing cells, and a majority of the cells coexpressing middle T and small t were resistant to p53-induced apoptosis. The phosphatidylinositol 3-kinase inhibitor wortmannin partially abrogated the protective effect of middle T but not small t on p53-induced apoptosis, indicating that middle T prevents p53-induced apoptosis through the phosphatidylinositol 3-kinase signal transduction pathway. Our results thus establish a mechanism for polyoma virus-mediated inhibition of p53 function.

Androstadienes↗
PubMed2000

The CUP trial: a randomized study analyzing the efficacy of high dose therapy and purging in low-grade non-Hodgkin's lymphoma (NHL).

BACKGROUND: The CUP trial was initiated to analyze the value of high-dose therapy and stem-cell transplantation and purging in patients with relapsed chemosensitive follicular NHL. PATIENTS AND METHODS: After three cycles of chemotherapy responsive patients were randomized to either three more cycles of the same chemotherapy (C), high-dose therapy followed by autologous unpurged (U) or purged (P) stem-cell transplantation. Purging was performed using a cocktail of monoclonals. Pretransplant conditioning consisted of cyclophosphamide (60 mg/kg x 2) and total body irradiation. RESULTS: Of the 140 patients registered from 26 centers in Europe, 89 fulfilled the criteria for randomization (C: 24, U: 33 and P: 32). Reasons for failure to randomize were: no response (28), persistent marrow infiltration (4), patient refusal (7), other (7), no data (5). With the current follow up (median 26 months from randomization) 16 (66%) in C are known to have progressed or relapsed, in contrast to 13 (39%) of U and 12 (37%) of the P patients (P-value 0.002). Overall survival is premature with the current available data. CONCLUSIONS: Patients in U and P arms had higher progression/relapse-free survival rate. There are some suggestions of some improvement in overall survival rate.

Adult↗
PubMed2000

Immobilization of antibodies on ultraflat polystyrene surfaces.

BACKGROUND: Functional antibody surfaces were prepared on ultraflat polystyrene surfaces by physical adsorption, and the uniform distribution of monoclonal antibodies against hepatitis B surface antigen (anti-HBs) on such surfaces and the presence of dense hepatitis B surface antigen (HBsAg) particles captured by immobilized antibodies were identified. METHODS: A model polystyrene film was spin-coated directly onto a silicon wafer surface. Atomic force microscopy was used to directly monitor the immobilization of anti-HBs antibodies and their specific molecular interaction with HBsAg. Enzyme immunoassay was also used to characterize functional antibody surfaces. RESULTS: A mean roughness of 2 A for areas of 25 microm(2) was produced. We found a uniform distribution of anti-HBs antibodies on ultraflat polystyrene surfaces and the presence of dense HBsAg particles bound to such anti-HBs surfaces after incubation with HBsAg. CONCLUSIONS: This study confirmed the potential of preparing dense, homogeneous, highly specific, and highly stable antibody surfaces by immobilizing antibodies on polystyrene surfaces with controlled roughness. It is expected that such biofunctional surfaces could be of interest for the development of new solid-phase immunoassay techniques and biosensor techniques.

Adsorption↗
PubMed2000

[Partial sympathectomy for treating palmar hyperhidrosis with VATS].

OBJECTIVE: To review the experience with partial sympathectomy for treating palmar hyperhidrosis with VATS. METHODS: Between July 1995 and June 1999, 50 patients with palmar hyperhidrosis (26 males and 24 females, mean age 26.7 years) were operated. The major symptom was excessive sweating of hands, feet, and axcillaries, sometimes in drops. Thoracoscopy was performed under general anesthesia with a standard single-lumen endotracheal intubation with the patient in a semi-sitting position and arms stretched at 90 degrees. The approach through two small ports on the chest wall was done using VATS. As the lung was depressed by CO(2) insufflation in a low pressure, an excellent view of the upper mediastinum was obtained. Ganglia T(2) through T(4), sometimes T(5) were resected with a electrocautery probe. Bilateral procedures were completed in the same position. RESULTS: All patients after operation became dry immediately after sympathetic denervation with a few minor complications. Occasional side effect was moderate compensatory sweating of the trunk. One case had recurrence but sweating was much less than before operation. CONCLUSIONS: Because of excellent view of the upper mediastinum for sympathetic denervation of the hand and axcillaryies, the effect of partial sympathectomy for palmar hyperhidrosis is satisfactory and permanent.

Adolescent↗
PubMed2000

[Intrathecal synthesis of the anti-Hu antibody in patients with paraneoplastic encephalomyelitis or sensory neuronopathy].

OBJECTIVE: To probe into the pathogenic mechanisms of paraneoplastic encephalomyelitis (PEM) or sensory neuronopathy(PSN). METHODS: The serum and cerebral spinal fluid(CSF) anti-Hu antibodies and titers in 16 patients with PEM and 14 patients with PSN were detected with indirect immunohistochemistry (ABC) method. Intrathecal IgG synthesis and antibody specific activity (ASA) were calculated with Schuller's formulas according to the titers of the anti-Hu antibodies in the serum and CSF of the patients. Anti-Hu antibodies were identified by detecting the antigens of the nuclear extracts from the human cerebral cortex neurons with Western blot analysis. IgG in the serum and CSF and the albumin in the CSF were tested with electroimmunodiffusion method. RESULTS: The serum and CSF anti-Hu antibody titers in patients with PEM were significantly higher than those in patients with PSN (P < 0.001). A ratio of intrathecal ASA/serum ASA of anti-Hu antibody > 2 in 14 (88%) of the 16 patients with PEM and one (7%) patient with PSN indicated that the patients with PEM had a positive intrathecal anti-Hu antibody synthesis (P < 0.001). The Rankin scores are 4.5 +/- 1.7 in patients with PEM and 3.0 +/- 1.4 in patients with PSN (P < 0.01). Patients with PEM were more disabled than those with PSN. CONCLUSIONS: The detection of intrathecal ASA/serum ASA ratio for identifying the anti-Hu antibody intrathecal synthesis is valuable in judging the severity of disease and prognosis in patients with paraneoplastic syndromes of nervous system.

Adult↗
PubMed1999

[Nitric oxide in the nose and paranasal sinuses--respiratory tract physiology in a new perspective].

Nitric oxide (NO) has important functions in a variety of physiological and pathophysiological processes in the body, including vasoregulation, haemostasis, neurotransmission, immunity and respiration. The discovery of surprisingly high concentrations of NO in the nasal airway and paranasal sinuses has important implications for the understanding of airway physiology. The high NO levels in the nasal and paranasal airways contribute to the first line defence against microorganisms. Furthermore, autoinhalation of nasal NO may improve pulmonary function and other remote physiological processes. This airborne messenger system represents a new physiological concept of potential clinical importance. However, NO, like several other mediators, has a dualistic function. Airway NO levels are increased in airway inflammations, such as asthma and allergic rhinitis, but is reduced in cystic fibrosis and other conditions with ciliary dysfunction, sinusitis and after exposure to tobacco and alcohol. Consequently, NO may prove valuable as a non-invasive marker in the diagnosis and monitoring of airway pathologies.

Humans↗
PubMed1999

Effect of mutation at valine 61 on the three-dimensional structure, stability, and redox potential of cytochrome b5.

To elucidate the role played by Val61 of cytochrome b(5), this residue of the tryptic fragment of bovine liver cytochrome b(5) was chosen for replacement with tyrosine (Val61Tyr), histidine (Val61His), glutamic acid (Val61Glu), and lysine (Val61Lys) by means of site-directed mutagenesis. The mutants Val61Tyr, Val61Glu, Val61His, and Val61Lys exhibit electronic spectra identical to that of the wild type, suggesting that mutation at Val61 did not affect the overall protein structure significantly. The redox potentials determined by differential pulse voltammetry were -10 (wild type), -25 (Val61Glu), -33 (Val61Tyr), 12 (Val61His), and 17 mV (Val61Lys) versus NHE. The thermal stabilities and urea-mediated denaturation of wild-type cytochrome b(5) and its mutants were in the following order: wild type > Val61Glu > Val61Tyr > Val61His > Val61Lys. The kinetics of denaturation of cytochrome b(5) by urea was also analyzed. The first-order rate constants of heme transfer between cytochrome b(5) and apomyoglobin at 20 +/- 0.2 degrees C were 0.25 +/- 0.01 (wild type), 0.42 +/- 0.02 (Val61Tyr), 0.93 +/- 0.04 (Val61Glu), 2.88 +/- 0.01 (Val61His), and 3.88 +/- 0.02 h(-)(1) (Val61Lys). The crystal structure of Val61His was determined using the molecular replacement method and refined at 2.1 A resolution, showing that the imidazole side chain of His61 points away from the heme-binding pocket and extends into the solvent, the coordination distances from Fe to NE2 atoms of two axial ligands are approximately 0.6 A longer than the reported value, and the hydrogen bond network involving Val61, the heme propionates, and three water molecules no longer exists. We conclude that the conserved residue Val61 is located at one of the key positions, the "electrostatic potential" around the heme-exposed area and the hydrophobicity of the heme pocket are determinant factors modulating the redox potential of cytochrome b(5), and the hydrogen bond network around the exposed heme edge is also an important factor affecting the heme stability.

Animals↗