Biomedical subjects
Hao-Chien Wang
Publications and source records attributed to Hao-Chien Wang.
Posterior mediastinal arteriovenous malformation with atypical color Doppler sonographic findings.
An arteriovenous malformation (AVM) is an anomaly of capillary development that results in a direct connection between branches of an artery and veins, with no intervening capillary network. A definite diagnosis of AVM is usually made with angiography. We report the case of a posterior mediastinal AVM found on routine sonography in a 64-year-old woman with neglected hypertension and severe back pain. Color Doppler imaging showed 2 adjoined vascular structures without a typical mosaic-like flow pattern, and spectral Doppler analysis showed low-resistance flow and arteriovenous shunting in 2 adjoined vascular structures. The diagnosis was subsequently confirmed by angiography. Because disastrous bleeding could result if needle biopsy were performed inadvertently in the case of a suspected mediastinal AVM, we suggest that color Doppler sonography be attempted if there is an adequate acoustic window.
Usefulness of computed tomography-guided transthoracic small-bore coaxial core biopsy in the presence of a pneumothorax.
Transthoracic needle biopsy (TNB) is usually avoided in the presence of pneumothorax. The authors performed computed tomography (CT)-guided transthoracic core biopsy in the presence of pneumothorax in 13 patients (4.9%) selected from 265 patients who received CT-guided TNB over 4 years. These iatrogenic pneumothoraces were induced by previous ultrasound (US)-guided TNB (n = 5), transbronchial lung biopsy (n = 4), and CT-guided biopsy (n = 4). The time interval between previous thoracic intervention and CT-guided TNB ranged from 0 hours to 9 days after transbronchial lung biopsy (average, 4 days). A diagnostic core biopsy was performed in 12 of the 13 patients. Seven lesions proved to be malignant and five were benign. Failure of CT-guided transthoracic core biopsy occurred in a single patient with a previous US-guided biopsy within 24 hours. This patients demonstrated a progressively enlarging pneumothorax and was treated with air aspiration with CT guidance. A successful second biopsy was performed 7 days later after full expansion of the lung. There were no complications related to the procedures. The authors' experience suggests that CT-guided transthoracic core biopsy using small-bore coaxial technique can be safely performed with high-diagnostic yield in patients with stable iatrogenic pneumothorax.
Clinical features of pandrug-resistant Acinetobacter baumannii bacteremia at a university hospital in Taiwan.
BACKGROUND AND PURPOSE: The number of infections caused by Acinetobacter baumannii has increased in recent years and the emergence of pandrug-resistant A. baumannii (PDRAB) has been observed in Taiwan. The aim of this study was to evaluate the clinical features and outcomes of patients with bacteremia due to PDRAB. METHODS: From January 1999 to April 2002, 30 patients with PDRAB bacteremia were treated. We analyzed the clinical characteristics of these patients, including gender, underlying diseases, clinical manifestations, antibiotic treatment, and outcome. RESULTS: Bacteremia developed an average of 33 days after hospitalization and was hospital acquired in all cases. The source of bacteremia was identified in 19 patients (63.3%) and was most commonly from the respiratory tract. The overall mortality was 60% (18 patients). Among these, the cause of death was directly related to PDRAB bacteremia in 12. Underlying heart disease, shock, resuscitation, acute respiratory distress syndrome, mechanical ventilation, and multiple organ dysfunction score (MODS) were significant predictors of mortality after the development of PDRAB bacteremia. No specific antimicrobial therapy appeared to be effective. CONCLUSIONS: Clinical outcomes of patients with PDRAB bacteremia were related to the medical conditions of the patients at the time of development of bacteremia and could be predicted by the MODS. The only way to limit the spread is through strict preventive measures for nosocomial infection and antibiotic control.
Outcome and prognostic factors for patients with non-small-cell lung cancer and severe radiation pneumonitis.
PURPOSE: Radiation pneumonitis is a serious complication that develops after thoracic irradiation. The purpose of this study was to identify prognostic factors for severe radiation pneumonitis in patients with non-small-cell lung cancer. METHODS AND MATERIALS: The medical records of patients with non-small-cell lung cancer and severe radiation pneumonitis were reviewed. Variables were analyzed by univariate and stepwise multivariate analysis using the Cox regression model. RESULTS: Among the 31 patients, the mortality rate approached 50% in the first 2 months after the onset of radiation pneumonitis. The variables significantly associated with survival in the univariate analysis were tumor histologic feature, grade and extent (out-of-field or in-field) of radiation pneumonitis, oxygenation index, and serum albumin (<35 g/L or >or=35 g/L), and uric acid levels at the onset of radiation pneumonitis. Only the extent of radiation pneumonitis and serum albumin level were independently associated with survival in the multivariate analysis. CONCLUSION: The mortality rate of non-small-cell lung cancer patients with severe radiation pneumonitis is extremely high, and survival is much shorter in patients with out-of-field radiation pneumonitis or a low serum albumin level at the onset. Additional studies to investigate the factors precipitating out-of-field radiation pneumonitis should improve the management of irradiation complications.
Fas/Fas ligand pathway is involved in the resolution of type II pneumocyte hyperplasia after acute lung injury: evidence from a rat model.
OBJECTIVE: We used a rat model of acute lung injury to evaluate the role of apoptosis of type II pneumocytes in alveolar remodeling during the resolution phase. DESIGN: Controlled animal study. SETTING: University research laboratory. SUBJECTS: Sprague-Dawley rats. INTERVENTIONS: Sprague-Dawley rats had Escherichia coli lipopolysaccharide instilled transtracheally to induce acute lung injury. Animals were killed on various days after lipopolysaccharide instillation. Lung specimens from all animals were examined for the presence of apoptosis in type II pneumocytes by an in situ apoptosis assay and for proliferative nuclear antigen, cytokeratin-18, Fas, and Fas ligand with an immunohistochemical stain. Fas and Fas ligand expression in both lung tissue and bronchoalveolar lavage fluid was examined by Western blot analysis. MEASUREMENTS AND MAIN RESULTS: Histologic examination revealed that the lungs of rats with acute lung injury showed infiltration of numerous inflammatory cells in the intra-alveolar and/or interstitial space and hyperplasia of type II pneumocytes. Type II pneumocyte proliferation, detected by proliferative nuclear antigen staining, developed maximally around day 3 after acute lung injury. In the in situ apoptosis assay, positive signals in type II pneumocytes were obvious and were distributed diffusely in the lung parenchyma from day 1 after acute lung injury, became maximal around day 7, then declined until day 21. DNA fragmentation analysis revealed that a DNA ladder pattern was detectable from day 3, persisted until day 10, and disappeared after day 14. The major cell types expressing Fas ligand are macrophages and neutrophils. Western blot analysis showed that Fas ligand, both membrane-bound form and soluble form, was present from day 1 to day 21 after acute lung injury, with highest level occurring during the first week of acute lung injury. Fas expression in type II pneumocytes reached its maximum on days 3-5 and then gradually declined until day 21. Fas and Fas ligand expression appeared to proceed type II pneumocyte apoptosis. After the acute stage, Fas and Fas ligand expression declined, and type II pneumocyte apoptosis also decreased. These findings correlate with histologic resolution of type II pneumocyte hyperplasia. CONCLUSIONS: Our results confirm that type II pneumocyte proliferation in response to acute lung injury is mainly a reparative phenomenon. During the resolution phase of acute lung injury, extensive apoptosis of type II pneumocytes is the main cellular mechanism that accounts for the disappearance of these cells, and Fas/Fas ligand is involved in the resolution of type II pneumocytes. Our model may provide a useful tool to assess the mechanisms of tissue remodeling after acute lung injury.
Mature mediastinal teratoma: sonographic imaging patterns and pathologic correlation.
OBJECTIVE: To characterize the sonographic patterns of teratomas located within the mediastinum and to correlate them with pathologic findings, because there have been few reports concerning the application of sonography in the diagnosis of mediastinal teratoma. METHODS: Over a 9-year period, we carried out an image analysis of the sonographic findings of 28 mediastinal teratomas whose diagnoses were proved surgically. RESULTS: Sonography showed that 18 patients had a complex mass of heterogeneous echogenicity, including regional bright echoes (n = 12), acoustic shadows (n = 8), hyperechoic lines and dots (n = 7), soft tissue septa (n = 9), dermoid plugs (n = 6), and hypoechoic areas (n = 11). This type of mediastinal teratoma revealed, in pathologic findings, varying combinations of fat, sebaceous and mucinous materials, hair, mineralized elements, and multiple compartments. Eight patients had a homogeneous hyperechoic mass, and the 2 remaining patients had floating spherules within a cystic mass. Pathologically, the homogeneous mass mainly contained hair and sebaceous material. The floating spherules were also composed of sebaceous tissue and were above the fluid of the cyst. CONCLUSIONS: On the basis of the evaluation of the sonographic and pathologic findings, we described 3 major patterns of mediastinal teratoma: a complex mass of heterogeneous echogenicity, homogeneous high echogenicity within a solid mass, and floating spherules within a cystic mass. Thus, sonography can improve the diagnosis of mediastinal teratoma. However, additional prospective studies are needed to test the sensitivity and specificity of these sonographic patterns in the diagnosis of mediastinal teratoma.
Small-cell lung cancer presenting with Lambert-Eaton myasthenic syndrome and respiratory failure.
Lambert-Eaton myasthenic syndrome (LEMS) is a neuromuscular disorder characterized by defective neurotransmitter release at presynaptic terminals. It is caused by an IgG autoantibody reacting against voltage-gated calcium channels. Severe LEMS complicated by ventilatory failure is rare. We report a case of small-cell lung cancer (SCLC) presenting with LEMS and ventilatory failure in a 67-year-old man who initially presented with progressive limb weakness for 6 months and tachypnea with shallow breathing for 1 week. LEMS was diagnosed through electrophysiologic studies. Chest radiography and computerized tomography showed a huge mass lesion over the left anterior and middle mediastinum with an encasement of the left pulmonary artery. Cytologic examination of ultrasound-guided fine needle aspiration disclosed SCLC. Successful treatment in combination with plasma exchange and chemotherapy resulted in dramatic tumor regression and LEMS remission, which were confirmed by chest radiography and electrophysiologic studies. This case suggests that plasma exchange and chemotherapy can be effective in treating SCLC with severe LEMS that produces ventilatory failure.