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Biomedical subjects

Andrew Chang

Publications and source records attributed to Andrew Chang.

13 recordsLinked to original sources
PubMed2007

Vitamin D receptor expression by the lung micro-environment is required for maximal induction of lung inflammation.

Mice lacking the vitamin D receptor (VDR) are resistant to airway inflammation. Pathogenic immune cells capable of transferring experimental airway inflammation to wildtype (WT) mice are present and primed in the VDR KO mice. Furthermore, the VDR KO immune cells homed to the WT lung in sufficient numbers to induce symptoms of asthma. Conversely, WT splenocytes, Th2 cells and hematopoetic cells induced some symptoms of experimental asthma when transferred to VDR KO mice, but the severity was less than that seen in the WT controls. Interestingly, experimentally induced vitamin D deficiency failed to mirror the VDR KO phenotype suggesting there might be a difference between absence of the ligand and VDR deficiency. Lipopolysaccharide (LPS) induced inflammation in the lungs of VDR KO mice was also less than in WT mice. Together the data suggest that vitamin D and the VDR are important regulators of inflammation in the lung and that in the absence of the VDR the lung environment, independent of immune cells, is less responsive to environmental challenges.

Animals↗
PubMed2006

CT-guided thoracic core biopsies: value of a negative result.

Previous studies have reported low negative predictive values (NPV) for computed tomography (CT)-guided fine needle aspiration of lung nodules in excluding malignancy. Our aim was to determine the NPV of transthoracic core needle biopsy in a tertiary care hospital with a large cancer patient population. The results of 226 consecutive CT-guided transthoracic core needle biopsies were reviewed. Results were classified into one of the following four groups: positive or suspicious for malignancy, benign specific, benign non-specific, and non-diagnostic. The benign specific group included entities such as fungus, hamartoma and schwannoma. In the benign non-specific group, histologic findings such as scar and inflammation were reported. The non-diagnostic group included cases with only normal pulmonary tissue in the specimen and/or insufficient tissue to render any diagnosis. The results were correlated with subsequent proof obtained via surgery or clinical and imaging follow-up. Out of a total of 226 biopsies, 158 were positive or suspicious for malignancy, 8 were benign specific, 32 were benign non-specific and 28 were non-diagnostic. Forty-three benign non-specific or non-diagnostic cases had subsequent proof, and malignancy was subsequently confirmed in 16/43 cases (5/21 non-specific and 11/22 non-diagnostic cases). The NPVs were 76% and 50% for benign non-specific and non-diagnostic biopsies, respectively. The overall NPV and false negative rate were 68% and 9%, respectively. A core biopsy revealing non-specific benign tissue or insufficient tissue for diagnosis is unreliable in excluding malignancy, and patients with these types of biopsy results should have resampling of tissue or close clinical and imaging follow-up.

Biopsy, Fine-Needle↗
PubMed2005

Prognostic value of bronchiolitis obliterans syndrome stage 0-p in single-lung transplant recipients.

RATIONALE: Early diagnosis of bronchiolitis obliterans syndrome (BOS) is critical in understanding pathogenesis and devising therapeutic trials. Although potential-BOS stage (BOS 0-p), encompassing early changes in FEV(1) and forced expiratory flow, midexpiratory phase (FEF(25-75%)), has been proposed, there is a paucity of data validating its utility in single-lung transplantation. OBJECTIVE: The aim of this study was to define the predictive ability of BOS 0-p in single-lung transplantation. METHODS: We retrospectively analyzed spirometric data for 197 single-lung recipients. Sensitivity, specificity, and positive predictive value of BOS 0-p were examined over time using Kaplan-Meier methodology. RESULTS: BOS 0-p FEV(1) was associated with higher sensitivity, specificity, and positive predictive value than the FEF(25-75%) criterion over different time periods investigated. The probability of testing positive for BOS 0-p FEV(1) in patients with BOS (sensitivity) was 71% at 2 years before the onset of BOS. The probability of being free from development of BOS 0-p FEV(1) in patients free of BOS at follow-up (specificity) was 93% within the last year. Of patients who met the BOS 0-p FEV(1) criterion, 81% developed BOS or died within 3 years. The specificity and positive predictive value curves for the BOS 0-p FEV(1) were significantly different between patients with underlying restrictive versus obstructive physiology (p = 0.05 and 0.01, respectively). CONCLUSION: The FEV(1) criterion for BOS 0-p provides useful predictive information regarding the risk of development of BOS or death in single-lung recipients. The predictive value of this criterion is higher in patients with underlying restriction and is superior to the FEF(25-75%) criterion.

Bronchiolitis Obliterans↗
PubMed2005

The JCAHO patient safety event taxonomy: a standardized terminology and classification schema for near misses and adverse events.

BACKGROUND: The current US national discussions on patient safety are not based on a common language. This hinders systematic application of data obtained from incident reports, and learning from near misses and adverse events. OBJECTIVE: To develop a common terminology and classification schema (taxonomy) for collecting and organizing patient safety data. METHODS: The project comprised a systematic literature review; evaluation of existing patient safety terminologies and classifications, and identification of those that should be included in the core set of a standardized taxonomy; assessment of the taxonomy's face and content validity; the gathering of input from patient safety stakeholders in multiple disciplines; and a preliminary study of the taxonomy's comparative reliability. RESULTS: Elements (terms) and structures (data fields) from existing classification schemes and reporting systems could be grouped into five complementary root nodes or primary classifications: impact, type, domain, cause, and prevention and mitigation. The root nodes were then divided into 21 subclassifications which in turn are subdivided into more than 200 coded categories and an indefinite number of uncoded text fields to capture narrative information. An earlier version of the taxonomy (n = 111 coded categories) demonstrated acceptable comparability with the categorized data requirements of the ICU safety reporting system. CONCLUSIONS: The results suggest that the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) Patient Safety Event Taxonomy could facilitate a common approach for patient safety information systems. Having access to standardized data would make it easier to file patient safety event reports and to conduct root cause analyses in a consistent fashion.

Causality↗
PubMed2005

Surgical therapy for chronic obstructive pulmonary disease.

Many patients with severe chronic obstructive pulmonary disease (COPD) experience incapacitating breathlessness and exercise limitation. Multiple surgical techniques have been utilized to achieve resection of giant, localized bullae with documented short-term benefit in pulmonary function and dyspnea in highly selected patients. The poorest long-term outcome has been noted in those with greater degrees of emphysema in the remaining lung, greater underlying chronic bronchitis, and a bulla occupying less than one third of the hemithorax, particularly if compressed normal lung is not evident. Lung volume reduction surgery (LVRS) in the absence of giant bullae has become more widely accepted in selected patients. Bilateral LVRS procedures appear to result in greater short-term improvement than unilateral LVRS, whereas physiological benefits appear similar with video-assisted thoracoscopy (VATS) or median sternotomy (MS) techniques. Improvement in dyspnea and health status after LVRS has been documented and appears to be better preserved over longer-term follow-up than physiological improvement. Clear direction has been provided in identifying optimal candidates for bilateral LVRS; patients with a postbronchodilator forced expiratory volume in 1 second (FEV (1)) < or = 20% predicted and a diffusing capacity for carbon monoxide (DL (CO)) < or = 20% predicted or homogeneous emphysema exhibit a much higher mortality with LVRS than with medical management. Patients with upper-lobe predominant emphysema and a low postrehabilitation exercise tolerance exhibited a decreased risk of mortality after LVRS. Patients with non-upper lobe predominant emphysema on high-resolution computed tomography (HRCT) and a high postrehabilitation exercise capacity exhibit an increased risk of death after LVRS. Patients with upper lobe predominant emphysema and a high postrehabilitation exercise capacity or patients with non-upper lobe predominant emphysema and a low postrehabilitation exercise capacity do not have a survival advantage or disadvantage, whereas those with upper lobe predominant emphysema treated surgically are more likely to improve their exercise capacity after surgery. Lung transplantation is an option for a more limited number of patients. Consistent short-term spirometric improvement after both single- and double-lung transplant has been documented. Long-term results of lung transplantation are limited by significant complications that impair survival; an approximately 80% 1-year, 50% 5-year, and 35% 10-year survival has been reported. Bronchiolitis obliterans is the most important long-term complication of lung transplantation resulting in decreased pulmonary function. In general, a COPD patient can be considered an appropriate candidate for transplantation when the FEV (1) is below 25% predicted and/or the paCO (2) is > or = 55 mm Hg.

Disease Progression↗
PubMed2005

A reunification of the US ("NIH") and International Unit into a single standard for Thrombin.

The existence of two different units for Thrombin in widespread international use has caused confusion for many years. The holders of the WHO International Standard (IS) for Alpha Thrombin and the US Standard (also known as the "NIH Standard") now report on a collaboration to reunite the International Unit (IU) and the US unit ("NIH unit"). A study was organised involving 25 laboratories in 15 countries to investigate the possibility of preparing a common Standard with a common unit and to investigate aspects of methodology that cause divergence of results using the IS and US Standard. Laboratories were asked to measure the potency of two candidate replacement standards (C, 01/578 and D, 01/580), and potencies were calculated relative to both the existing US Standard (lot J) and the IS (89/588). Data analysis of a total of 128 assays indicated that sample D would make an ideal replacement joint Standard with a potency of 110 IU/ampoule (equivalent to 110 US units per ampoule) based on data from clotting assays. No significant differences in results were observed using fibrinogen of human or bovine origin, or using human plasma. Comparisons of chromogenic and clotting assays indicated that sample D had a similar high proportion of alpha thrombin to the current IS for Alpha Thrombin (89/588). Sample D was adopted as the IS for Thrombin (01/580) and the US Standard (lot K) with a potency of 110 IU/ampoule.

Animals↗
PubMed2005

Building a Hospital Incident Reporting Ontology (HIRO) in the Web Ontology Language (OWL) using the JCAHO Patient Safety Event Taxonomy (PSET).

A Hospital Incident Reporting Ontology (HIRO) is being developed in Protégé-OWL to demonstrate feasibility and clinical value of using an ontology to combine, compare, and analyze data from across many public and private reporting systems collecting adverse events and near misses for patient safety. The HIRO is based on the JCAHO Patient Safety Event Taxonomy (PSET) and de-identified hospital incident reports.

Humans↗
PubMed2004

Sympathetic ophthalmia following ciliary body laser cyclophotocoagulation for rubeotic glaucoma.

A 60-year-old Asian man presented with left rubeotic glaucoma secondary to a central retinal vein occlusion. He was successfully treated with laser diode cyclophotocoagulation of the ciliary body. Nine months later he developed right progressive visual loss, headache, corneal oedema, anterior chamber cells, flare, mutton fat keratic precipitates, a swollen disc, and a minimal inferior visual field defect. A diagnosis of sympathetic ophthalmia was made, which was confirmed by characteristic findings seen on fluorescein and indocyanine green angiography.

Ciliary Body↗
PubMed2004

Scleral buckle intrusion.

A case is reported of a 72-year-old man with an intruded scleral buckle presenting 30 years after retinal detachment repair. The lesion was noted incidentally and occupied the superotemporal retinal periphery. The diagnosis was confirmed by B-scan ultrasonography and external examination of the globe. The patient was treated conservatively. No clinical change was evident after 12 months follow up.

Aged↗
PubMed2003

Acute inhalation injury.

The lungs can be an efficient means for the absorption of inhaled toxicants, resulting in airway and pulmonary injury or systemic toxicity. Although a few specific antidotes exist for inhaled toxicants, the syndrome of acute inhalation injury and clinical therapeutics are linked by common pathways of pathophysiology. Understanding the mechanisms of inhalation injury and occupation- or situation-specific toxicants can simplify the decision-making process for the out-of-hospital emergency responder and the emergency physician when confronted with a patient and the myriad of potential inhaled toxicants.

Acute Disease↗
PubMed2002

Indocyanine green angiographic interpretation of reticular dystrophy of the retinal pigment epithelium complicated by choroidal neovascularization.

A 37-year-old woman presented with flashes in her left eye and bilateral visual distortion. Fundal examination revealed a reticular 'fishnet' pattern of retinal pigmentation in both eyes consistent with reticular dystrophy of the retinal pigment epithelium. In the left eye there was a small haemorrhage and a shallow serous macular detachment. Fluorescein angiography demonstrated subfoveal choroidal neovascularization. Indocyanine green angiography (ICG) revealed more extensive involvement than fluorescein angiography, with small areas of intense hyperfluorescence amongst reticular areas of hypofluorescence. These changes, as interpreted in light of the known histopathological localization of ICG, are consistent with varying stages of dysfunction of the retinal pigment epithelium in this disease.

Adult↗