Structure-activity studies of ground- and transition-state analogue inhibitors of cyclophilin

Peptidyl-prolyl isomerases (PPIases) are ubiquitous cellular enzymes that play roles in cellular signaling and protein folding. In addition, these proteins are the receptors for the widely used immunosuppressants cyclosporin A and FK506. We report the first structure-activity studies of de novo designed inhibitors of cyclophilin, the cellular target of cyclosporin A. Our mechanism-based inhibitors were modeled on the ground- and transition-state structures of proline-containing peptides, the natural substrates of the enzyme. Both ground-state analogues 1 and transition-state analogues 2 were prepared as single enantiomers from L-proline following a "self-reproduction of chirality" procedure. The binding affinities of the analogues for the active site of cyclophilin were measured by a fluorescence perturbation assay. While the transition-state analogues 2 did not display significant avidity for the active site (K(d) = 77 microM for 2b), several ground-state analogues bound to the enzyme with low micromolar affinity (K(d) = 1.5 microM for 1e). These results proclaim that properly designed small molecular weight molecules can form strong complexes with cyclophilin and may find use as probes in cell biology and as therapeutic agents.

Treatment of neuroleptic malignant syndrome with subcutaneous apomorphine monotherapy

A 20-year-old psychiatric patient receiving haloperidol treatment developed acute-onset fever, rigidity, and mental changes. Subcutaneous apomorphine was given alone for treatment. The patient had rapid clinical improvement after the treatment. Serial blood examinations showed decline and subsequent normalization of the creatine phosphokinase levels.

CD43 potentiates CD3-induced proliferation of murine intestinal intraepithelial lymphocytes

The involvement of CD43 in cell proliferation of murine intestinal intraepithelial lymphocytes (IEL) has been studied in in vitro CD3-stimulated cell cultures. In the presence of either IL-2 or IL-15, CD3 stimulation of IEL resulted in low levels of proliferation as measured by thymidine incorporation, whereas no proliferation occurred upon CD3 stimulation in the absence of cytokines. The combination of both cytokines to IEL cultures synergistically enhanced CD3-induced proliferation by approximately threefold that of cultures supplemented with either cytokine alone. Most importantly, however, proliferation of IEL was significantly greater when CD3 stimulation occurred in conjunction with CD43 triggering, indicating that CD43 functions as a coactivational signal for murine IEL. These findings indicate that a spectrum of potential proliferative responses exist among murine IEL depending on the types and combinations of signals received, and that because under normal conditions murine IEL are largely devoid of CD28 expression, a classical T-cell coactivational molecule, the capacity for high-level IEL proliferation may reside with CD43.

Gaseous nitric oxide-induced 8-nitroguanine formation in human lung fibroblast cells and cell-free DNA

A time- and dose-dependent increase in 8-nitroguanine (8-NO(2)-G) was observed in human lung fibroblast cells (MRC-5) after treatment with gaseous NO-saturated buffer. It was also found that treatment with the inhibitor of inducible nitric oxide synthase (iNOS), N(G)-nitro-l-arginine methyl ester, significantly reduced the 8-NO(2)-G level in the gaseous NO-saturated buffer-treated MRC-5 cells. These results provide evidence indicating that NO gas causes DNA damage in mammalian cells, which involves the activation of iNOS and the subsequent generation of endogenous NO. On the other hand, a time- and dose-dependent increase in 8-NO(2)-G was also observed while DNA (isolated from MRC-5 cells) was incubated with gaseous NO-saturated buffer. These results suggest that part of the 8-NO(2)-G formation was due to direct modification of gaseous NO on DNA. Furthermore, an increase in nitrite concentration was found in both cell-free and MRC-5 cell-conditioned medium treated with gaseous NO-saturated buffer. Collectively, gaseous NO induced DNA damage by forming 8-NO(2)-G, a modification performed directly by the treated gaseous NO and indirectly by the following induction of endogenous NO. This effect might be an important pathway in genotoxicity of nitric oxides, and 8-NO(2)-G could act as a specific marker for DNA damage induced by gaseous NO, a common contaminatant in air pollution and cigarette smoke.

Analysis of codon usage patterns of bacterial genomes using the self-organizing map

Codon usage varies both between organisms and between different genes in the same organism. This observation has been used as a basis for earlier work in identifying highly expressed and horizontally transferred genes in Escherichia coli. In this work, we applied Kohonen's self-organizing map to analysis of the codon usage pattern of the Escherichia coli, Aquifex aeolicus, Archaeoglobus fulgidus, Haemophilus influenzae RD:, Methanococcus jannaschii, Methanobacterium thermoautotrophicum, and Pyrococcus horikoshii genomes for evidence of highly expressed genes and horizontally transferred genes. All of the analyzed genomes had a clear category of horizontally transferred genes, and their apparent percentages ranged from 7.7% to 21.4%. The apparent percentage of highly expressed genes ranges from 0% to 11.8%. A clustering of average codon usage of main gene categories of the seven genomes showed an interesting mixing of gene classes in four thermophilic/hyperthermophilic organisms, A. aeolicus, A. fulgidus, M. thermoautotrophicum, and P. horikoshii, which suggests possible origins of their horizontally transferred genes as well as the need for adaptation to a specific environment. Further classification of the three gene categories in E. coli and H. influenzae according to gene function revealed that genes involved in communication (such as regulation and cell process) and structure (cell structure and structural proteins) are more likely to be horizontally transferred than are genes involved in information (transcription, translation, and related processes) and in some groups of energy (such as energy metabolism and carbon compound catabolism).

Tie-1 tyrosine kinase is an independent prognostic indicator for invasive breast cancer

Receptor tyrosine kinases are known to be involved in the growth, progression and metastasis of solid tumors. We investigated the relationship between tie-1 expression and progression of invasive ductal breast carcinoma with immunohistochemical analysis. Tie-1 protein was detected in the microvessel endothelial cells and cytoplasm of tumor cells. The tumor size and stage were significantly associated with the expression of tie-1, which portends a worse 5-year disease-free status (39.3% v 59.2%, p = 0.07) and overall survival rate (67.3% v 93%, p = 0.02) than those without tie-1 expression. Multivariate analysis demonstrated that larger tumor size, presence of lymph node metastasis and tie-1 expression were independent prognostic parameters, both in 5-year disease-free survival and overall survival. Patients with lymph node metastases and tie-1 expression had the worst 5-year disease-free survival (0%) and overall survival (42.4%) compared to those without tie-1 expression (50.2%, 85%). In lymph node negative patients, those without tie-1 expression had better 5-year disease-free survival and overall survival (72.9%, 100%) compared to those with tie-1 expression (65.5%, 87.7%). We conclude that tie-1 expression is an independent prognostic factor for invasive ductal breast carcinoma, adversely affecting survival of breast cancer patients with positive nodes to a significant extent.

Determination of beryllium and selenium in human urine and of selenium in human serum by graphite-furnace atomic absorption spectrophotometry

For human urine beryllium (Be), each sample (500 microl) was diluted (1+1) with Nash reagent (containing 0.2% (v/v) acetylacetone and 2.0 M ammonium acetate buffer at pH 6.0) and then a 20-microl volume of Triton X-100 (0.4%, v/v) aqueous solution was added. An aliquot (10 microl) of the diluted urine mixture was introduced into a graphite cuvette and was atomized according to a temperature program. The method detection limit (MDL, 3sigma) for Be was 0.37 microg/l in the undiluted urine sample and the calibration graph was linear up to 65.0 microg/l. Calibration graphs were prepared by the standard addition method. Accuracies of 98.6-102% were obtained when testing standard reference material (SRM 2670) freeze dried human urine samples. Precision (relative standard deviation, RSD) for urine Be was < or = 2.3% (withinrun, n = 5) and was < or = 3.0% (between-run, n = 3). For human urine and serum selenium (Se), samples (100 microl) were diluted with HNO3 (0.2%, v/v) to make a (1+1) dilution for urine analysis or a (1+4) dilution for serum analysis. An additional aliquot (10 microl) of Triton X-100 (0.1%, v/v) was added to each 200 microl of (1+1) diluted urine (or 20 microl of the Triton X-100 was added to each 500 microl of (1+4) diluted serum) sample. After the diluted sample mixture (10 microl) was introduced into a graphite cuvette, the corresponding chemical modifier (10 microl, containing Ni2+ + Pd + NH4NO3 in HNO3 (0.2%, v/v)) was added to it and the mixture was atomized. The MDL (3sigma) for Se in urine and in serum was 4.4 and 21.4 microg/l in undiluted sample, respectively, and the calibration graphs were linear up to 150 and 400 microg/l. Accuracies of urine Se were 98.9 - 99.4% by testing SRM 2670 (NIST) urine standards with RSD (between-run, n = 3) within 2.9%; and that of serum Se was 97.2% when testing a certified second-generation human serum (No. 29, #664) with RSD (between-run, n = 3) of 1.4%. The proposed method can be applied easily, directly, and accurately to the measurement of Be and Se in real samples (including six urine Se and four serum Se from patients of Blackfoot Disease in Taiwan).

Mutations of p53 gene in human colorectal cancer: distinct frameshifts among populations

We analyzed 57 p53 gene mutations in 181 colorectal cancer patients in Taiwan and compiled data on 475 independent p53 mutations in 1,156 primary colorectal cancer patients worldwide between 1992 to 1998. Transitions at the CpG sites were observed in 31 (54%) and 232 cases (49%), respectively. Frameshift mutations occurring within exons were observed in 11 (20%) and 50 cases (10%), respectively. Among the various populations studied, colorectal cancer in Taiwan had the lowest p53 mutation rate (31%), highest frequency (20%) of frameshift mutations and the second lowest rate (13%) of transversion mutation. Based on their relation to the base runs, the 61 frameshift mutations could be grouped into 4 subclasses. After corrections were made for differences in the base number in a run, the relative mutational frequency at a base run was found to be 9- to 47-fold over that in the no-run residues. The p53 frameshift mutational spectrum found in the cases in Taiwan, with respect to hotspot sequence, was significantly different from those in the selected database (p = 0.008). These data support that the patterns of high frequency of transitions at CpG sites and low frequency of transversions in base substitutions in the p53 gene are similar regardless of patient origin. However, these data also illustrate that frameshift mutations in the p53 gene in colorectal cancer patients are sequence dependent and are distinct among populations.

In-situ EXAFS study of copper in the electrokinetic remediation process

The speciation of copper in the early stage of the electrokinetic remediation (EKR) process has been studied by extended X-ray absorption fine structure (EXAFS) spectroscopy in the present work. By in-situ EXAFS, we found that copper in a contaminated soil possessed a Cu-O bond distance of 1.98 A with a coordination number (CN) of 5.8. In the second shell, the bond distance of Cu-(O)-Cu was 2.87 A with a CN of 6.4. However, possibly due to the fact that incompact copper atoms in the outer shells were distorted by EKR, the Cu-(O)-Cu (2nd shell) bond distance and the CN of copper in the contaminated soil decreased by 0.08 A and 5.4, respectively in the early stage of the EKR process. Interestingly, after prolonging the contact time to about 80 minutes, the 1st-shell copper atoms were also perturbed by EKR. This work is an example of usefulness of the in-situ EXAFS spectroscopy for detailed studies of the speciation of copper in the contaminated soil during EKR process.

Speciation of As in the blackfoot disease endemic area

Speciation of arsenic (As) in well water and contaminated soil in the blackfoot disease endemic area has been studied by extended X-ray absorption fine structural (EXAFS) spectroscopy in the present work. Experimentally, we found that arsenic in the well water possessed an As-O bond distance of 1.72 A with a coordination number (CN) of 4.3. In the blackfoot disease area, arsenic with a high oxidation state (As(V)) was also observed in the contaminated soil. In the early stage (after 90 minutes) of the electrokinetic remediation (EKR) of the contaminated soil, the in-situ EXAFS data indicated that the CN of As-O (1st shell) decreased slightly, that may be due to the perturbation of the incompact As atoms in the outer shells by EKR.

Increased expression of iNOS and c-fos via regulation of protein tyrosine phosphorylation and MEK1/ERK2 proteins in terminal bronchiole lesions in the lungs of rats exposed to cigarette smoke

Epidemiological evidence suggests that smoking is a major cause of human lung cancer. However, the mechanism by which cigarette smoke induces the cancer remains unestablished. To evaluate the effects of cigarette smoke on the expression of inducible nitric oxide synthase (iNOS), nuclear protooncogenes and related mitogen-activated protein kinases (MAPKs) in rat lung tissue, a histopathological study of the effects of gas-phase cigarette smoke on rat lung tissue were carried out. The terminal bronchioles were found to be infiltrated predominantly by lymphocytes in the peribronchiolar region and a mild to moderate degree of emphysema was noted in the alveolar spaces. The terminal bronchioles also showed marked lipid peroxidation, dilatation, and peribronchiolar fibrosis. Immunohistochemical evaluation showed that the expression of iNOS, NF-kappa B, MAPKs (MEK1, ERK2), phosphotyrosine protein and c-fos was increased in the terminal bronchioles but protein kinase C (PKC), MEKK-1, c-jun, p38 and c-myc showed no change. These results provide evidence to suggest that exposure to cigarette smoke results in oxidant stress which leads to the stimulation of iNOS and c-fos together with the induction of protein tyrosine phosphorylation and MEK1/ERK2 which in turn may promote lung pathogenesis.

Sequencing and amplified restriction fragment length polymorphism analysis of ribonucleotide reductase large subunit gene of the white spot syndrome virus in blue crab (Callinectes sapidus) from American Coastal Waters

In the present study, the existence of white spot syndrome virus (WSSV) in blue crab (Callinectes sapidus) collected from 3 different American coastal waters (New York, New Jersey, and Texas) was confirmed by 2-step diagnostic polymerase chain reaction and in situ hybridization analysis. When geographic isolates were also compared using a gene that encodes the WSSV ribonucleotide reductase large subunit RR1 (WSSV rr1), a C(1661)-to-T point mutation was found in the New Jersey WSSV isolated. This point mutation, which resulted in the creation of an additional RsaI endonuclease recognition site, was not found in the WSSV from the New York and Texas blue crab samples, or in the WSSV Taiwan isolate, or in any of the other WSSV geographical isolates for which data are available. WSSV rr1-specific RsaI amplified restriction fragment length polymorphism of an amplified 1156-bp fragment thus distinguished the New Jersey blue crab samples from the other WSSV isolates.

Prevalence and significance of hepatitis B virus (HBV) pre-S mutants in serum and liver at different replicative stages of chronic HBV infection

Several types of naturally occurring pre-S mutants in sera or liver tissues in patients with chronic hepatitis B virus (HBV) infection have been identified. To clarify the prevalence and significance of emergence of pre-S mutants, 140 sera and 18 resected livers from patients with HBV were studied. Replicative status was designated as high, intermediate, and low based on the HBV-DNA levels in serum or the expression of HBV antigens in liver. In vitro transfection and Western blot analysis were performed to characterize expression and secretion of HBsAg by the mutant constructs. Five major types (I to V) of pre-S deletion mutants in serum and liver and 2 types (VI and VII) in liver were identified. Pre-S mutant was 6.4% at high replicative phase, 13% at intermediate, and 37.5% at low or nonreplicative phases in serum. In livers, the same tendency existed: pre-S2 deletion mutants emerged and prevailed at a low replicative phase in hepatocytes that expressed a novel marginal pattern of HBsAg and usually clustered in groups. The deletion sequence of pre-S2 region coincides with human leukocyte antigen-restricted T- and B-cell epitopes. In vitro HBsAg was retained in the hepatocytes and synthesis and secretion of major surface antigen decreased for most of the pre-S mutants. Pre-S mutants prevailed with evolution of chronic HBV, probably under immune pressure. Emergence of pre-S mutants may account for the life-long persistence and discrepancy of HBsAg in serum and liver in HBV and may confer growth advantage in view of the clustering proliferation of hepatocytes harboring pre-S2 mutant.

Sonographic septation: a useful prognostic indicator of acute thoracic empyema

The aim of this study was to identify sonographic predictors of patient outcomes or need for surgical intervention of acute thoracic empyema. All patients with a clinical diagnosis of thoracic empyema underwent transthoracic ultrasonographic examination and thoracentesis at admission. According to the presence or absence of septa in sonographic images, the patients were classified into two groups: septated and nonseptated. Sonographic findings were analyzed with respect to duration of hospital stay, chest tube drainage, and treatment efficacy. A total of 163 consecutive patients were included in the study (83 patients with septated and 80 with nonseptated sonographic images). The mean duration of hospital stay (35.4 versus 27.0 days, P = 0.009) and chest tube drainage (13.1 versus 7.6 days, P < 0.001) for the patients with septa were significantly longer than for those without septa. The patients with septa were more likely to undergo intrapleural fibrinolytic therapy (63.8% versus 38.8%, odds ratio 2.79, P = 0.001) and surgical intervention (24.3% versus 7.5%, odds ratio 3.92, P = 0.004). We concluded that sonographic septation is a useful sign to predict the need for subsequent intrapleural fibrinolytic therapy and surgical intervention in cases of acute thoracic empyema. Early fibrinolytic therapy or even surgical intervention may be indicated in patients with sonographic septations.

Interaction of shrimp ras protein with mammalian caveolin-1

BALB/3T3 cells were transformed by transfection with DNA encoding the mutated ras(Q(61)K) from shrimp Penaeus japonicus (Huang and Chuang. 1999. J Exp Zool 283:510-521). The caveolin-1 in the membrane fraction extractable with 2% octyl glucoside was significant reduced, compared to untransformed cells. To understand this in more detail, the interaction of S-Ras with caveolin was investigated using caveolin-1 purified from rat lungs. The purified caveolin-1 binds c-Src, suppressing its autophosphorylation. It also binds to phosphatidylserine-cholesterol liposomes. These reconstituted caveolin-phosphatidylserine-cholesterol vesicles, which act as a model of caveolae, recruit both bacterially expressed S-Ras and rat K(B)-Ras proteins, as demonstrated on western blots with antibodies against caveolin-1 and Ras. Caveolin-1 suppressed the intrinsic GTPase activity of S-Ras, sustaining it in the active GTP bound form. By contrast, caveolin-1 enhanced the intrinsic GTPase activity of K(B)-Ras, to convert it into the inactive GDP-bound form. These events suggest that caveolin may act as a docking site for Ras proteins and may be able to either maintain or alter their activity state. These events may be associated with the ability of S-ras(Q(61)K) to successfully transform cells.

Catamenial hemoptysis from tracheobronchial endometriosis: reappraisal of diagnostic value of bronchoscopy and bronchial brush cytology

OBJECTIVES

To analyze the clinical data of four patients with a diagnosis of tracheobronchial endometriosis, and to reappraise the diagnostic value of bronchoscopy and bronchial brush cytology in these patients.

METHODS

We conducted a retrospective study of four patients with documented tracheobronchial endometriosis treated at National Taiwan University Hospital from 1994 to 1998. The complete histories, diagnostic time interval, results of physical examinations, laboratory data, bronchoscopic findings, cytologic results, chest radiographs, and chest CT of these patients were analyzed.

RESULTS

These patients tend to be younger and nonmultiparous as compared to other patients with thoracic endometriosis. Bronchoscopic examination performed within 1 day or 2 days of menses disclosed multiple purplish-red submucosal patches bilaterally that bled easily when touched. Cytologic evaluation of the brushing specimens demonstrated clusters of small cuboid cells consistent with an endometrial origin. Follow-up bronchoscopic examination in the middle of the menstrual cycle showed disappearance of the previous tracheobronchial lesions. The mean diagnostic interval was 3.25 months. All four patients were successfully treated with danazol therapy.

CONCLUSIONS

Tracheobronchial endometriosis consists of a special subgroup of patients with thoracic endometriosis. Proper timing of bronchoscopic examination plays an important diagnostic role in these patients. Cytologic features as well as cyclic changes in bronchoscopic findings are sufficient to warrant the diagnosis. The results of treatment with danazol in these patients seemed favorable.

Crystallization and preliminary crystallographic studies of bar-headed goose fluoromethaemoglobin with inositol hexaphosphate

Bar-headed goose fluoromethaemoglobin (fluoromet-Hb) complexed with inositol hexaphosphate (IHP) has been crystallized using PEG 6000 as precipitant. The crystal belongs to space group P2(1), with unit-cell parameters a = 59.8, b = 72.0, c = 79.8 A, beta = 102.1 degrees, and diffracts to 2.5 A resolution. To prove the presence of IHP, the structure was determined by the molecular-replacement method. IHP was observed at the entrance to the central cavity between the N and C termini of two beta subunits.

Detection of a novel quiescence-dependent protein kinase

We have identified a cell quiescence-specific 33-kDa cytoplasmic protein kinase (p33(QIK), Quiescence-Induced Kinase) based on induction of p33(QIK)-specific kinase activity of cells growth-arrested in the quiescent phase and deactivation upon entry into the cell cycle. Blockage of macromolecular synthesis prevents p33(QIK) from deactivation, indicating a requirement of newly synthesized regulators for deactivation of p33(QIK) during G(0)/G(1) transition. Stress shock induces additional increases of p33(QIK) activity in a quiescence-dependent manner that correlates with induction of apoptosis. Using a specific antibody to Krs1/Mst2 protein, we found that p33(QIK) is related to p63(Krs1) and is distinguishable from a 36-kDa protein kinase, which is induced through proteolytic modification of activated p63(Krs1) in proliferating cells undergoing apoptosis. p33(QIK) is constantly expressed in quiescent, proliferating, and apoptotic quiescent cells. Regulation of p33(QIK) activity involves protein phosphorylation/dephosphorylation in a proteolysis-independent manner. Regulation of p33(QIK) and related p63(Krs1) and p36 appears to involve distinct pathways in quiescent and proliferating cells, respectively. Our results illustrate the relevance of p33(QIK) activity for cell quiescence that may provide a new insight into signaling pathways regulated in cells during quiescence and quiescence-related apoptosis.

Clinical spectrum of acute respiratory distress syndrome in a tertiary referral hospital: etiology, severity, clinical course, and hospital outcome

BACKGROUND AND PURPOSE

The clinical picture of patients with acute respiratory distress syndrome (ARDS) in Taiwan has seldom been reported, although new definitions of ARDS have been introduced over the past years. The purpose of this study was to investigate the clinical characteristics, modalities of management, and outcomes in patients with ARDS treated in a tertiary referral hospital.

METHODS

Case records were selected through a computerized search of diagnosis codified at discharge during the period from January 1995 to June 1997. Patients who met the criteria of the American-European Consensus Conference definition of ARDS were included and their medical records were retrospectively reviewed.

RESULTS

A total of 145 patients (91 men, 54 women; mean age, 58 years) who fulfilled the criteria for ARDS were identified. Malignancy (n = 53) and diabetes mellitus (n = 23) were the most common co-morbid conditions. Pneumonia (n = 90), including community-acquired pneumonia in 45 (31%) patients, was the most common risk factor. The lung injury score at the time of ARDS diagnosis was 2.89 +/- 0.40 (mean +/- standard error, SE). The worst value of PaO2/FIO2 was 86.8 +/- 3.8 mm Hg (mean +/- SE). Among the 145 patients, 130 (90%) received mechanical ventilation and 118 (81%) were treated in the intensive care unit. In-hospital mortality was 87%. Seventy (48%) patients received intensive treatment for ARDS, among whom 52 (74%) died; the most common causes of death were multiple organ failure (54%) and respiratory failure (23%).

CONCLUSIONS

The mortality in patients with ARDS was high in this tertiary referral institution. Our findings suggest that aggressive ventilatory, pharmacologic, and supportive therapy may be important to achieve a higher survival rate.

Bacteriology of infected cavitating lung tumor

Differentiation between in situ infection and simple tumor necrosis in cavitating lung tumors by means of imaging studies is difficult. In this study, we prospectively investigated the role of ultrasound (US)-guided transthoracic aspiration for bacteriologic examination of infected cavitating lung tumors, and the influence of the culture results on the treatment of patients. Twenty-two patients (18 men and four women) with cavitating lung tumors treated from January 1996 to October 1998 were included. All patients underwent US-guided transthoracic aspiration for bacterial, fungal, and mycobacterial cultures. Microorganisms were isolated from six of seven febrile patients and one of 15 nonfebrile patients. A total of nine pathogens were isolated from seven patients: Klebsiella pneumoniae (n = 3); Haemophilus influenzae (n = 2); Enterococcus faecium (n = 1); Bifidobacterium (n = 1); Shewanella putrefaciens (n = 1); and Mycobacterium tuberculosis (n = 1). Two pathogens were isolated from the aspirate cultures in two patients, while the others had monomicrobial infection. The six febrile patients who had positive lung aspirate cultures were treated with empiric antimicrobial agents before the culture results were available, and the culture results led to adjustment of the antibiotic regimen in five of these. The clinical conditions of the six patients with infected cavitating lung tumors improved after the initiation of individualized antimicrobial treatment. Pneumothorax occurred in one patient, and was the sole procedure-related complication. In conclusion, US-guided transthoracic aspiration is helpful for differentiating infected cavitating lung tumors from simple tumor necrosis. Infection in cavitating lung tumors is common among febrile patients, and the culture results can guide modification of the antimicrobial therapy.

Oxidative stress disrupts glucocorticoid hormone-dependent transcription of the amiloride-sensitive epithelial sodium channel alpha-subunit in lung epithelial cells through ERK-dependent and thioredoxin-sensitive pathways

The amiloride-sensitive epithelial Na(+) channel (ENaC) plays a critical role in the maintenance of alveolar fluid balance. It is generally accepted that reactive oxygen and nitrogen species can inhibit ENaC activity and aggravate acute lung injury; however, the molecular mechanism for free radical-mediated ENaC inhibition is unclear. Previously, we showed that the expression of the alpha-subunit of ENaC, alpha-ENaC, which is indispensable for ENaC activity, is repressed by Ras activation in salivary epithelial cells. Here, we investigated whether exogenous H(2)O(2) modulates alpha-ENaC gene expression in lung epithelial cells through a similar molecular mechanism. Utilizing transient transfection reporter assays and site-directed mutagenesis analyses, we found that the glucocorticoid response element (GRE), located at -1334 to -1306 base pairs of the alpha-ENaC 5'-flanking region, is the major enhancer for the stimulated alpha-ENaC expression in A549 lung epithelial cells. We further demonstrate that the presence of an intact GRE is necessary and sufficient for oxidants to repress alpha-ENaC expression. Consistent with our hypothesis, exogenous H(2)O(2)-mediated repression of alpha-ENaC GRE activity is partially blocked by either a specific inhibitor for extracellular signal-regulated kinase (ERK) pathway activation, U0126, or dominant negative ERK, suggesting that, in part, activated ERK may mediate the repressive effects of H(2)O(2) on alpha-ENaC expression. In addition, overexpression of thioredoxin restored glucocorticoid receptor action on the alpha-ENaC GRE in the presence of exogenous H(2)O(2). Taken together, we hypothesize that oxidative stress impairs Na(+) transport activity by inhibiting dexamethasone-dependent alpha-ENaC GRE activation via both ERK-dependent and thioredoxin-sensitive pathways. These results suggest a putative mechanism whereby cellular redox potentials modulate the glucocorticoid receptor/dexamethasone effect on alpha-ENaC expression in lung and other tight epithelia.

Hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia was first described by Thurnam in 1848. It is a rare, X-linked, recessive disorder characterized by anhidrosis or hypohidrosis, hypotrichosis, dental hypoplasia and characteristic facial features. Herein, we report a typical case of hypohidrotic ectodermal dysplasia. A 20-year-old male presented with the above symptoms at birth. When a family history was taken, it was discovered that his uncle (mother's brother) had the same characteristic facial features and hypotrichosis.

Chronic myeloid leukemia initially presenting with spontaneous mediastinal hematoma and hemothorax

Spontaneous mediastinal hematoma is rarely seen in hematologic malignancy. We report a case of chronic myeloid leukemia initially presenting with spontaneous hematoma and hemothorax. In addition to a detailed history, computerized tomography of the chest is important in analyzing whether an anterior mediastinal mass lesion is present. Magnetic resonance imaging is helpful in confirming the nature of a mediastinal hematoma. Trauma, vascular disease and coagulopathy should first be ruled out when making a diagnosis of spontaneous bleeding in the thorax. In our patient, the mediastinal hematoma regressed spontaneously after three months. Leukemia should be considered in the differential diagnosis of spontaneous mediastinal hematoma. In leukemia patients with spontaneous mediastinal hematoma, supportive observation and close follow-up may be better than surgery, unless massive hemorrhage or active bleeding in the thorax is suspected.