Compliance with new drug use and the effect of discrepant drug susceptibility testing on MDR/RR-TB treatment

BACKGROUND: Following the WHO???s announcement in 2018, the use of new drugs was recommended for all patients with multidrug-resistant TB (MDR-TB) in Korea. This study aimed to evaluate adherence to new anti-TB drug regimens and implementation of molecular drug susceptibility testing (mDST) in Korea.METHODS: Nationwide, 560 patients were reported as having MDR-TB in 2021. The implementation of mDST and new anti-TB drug use were analysed. The discrepancy between mDST and phenotypic DST (pDST) results and their implications on the use of new anti-TB drugs were also analysed. The use of novel anti-TB drugs has been approved by the National TB Expert Committee.RESULTS: The non-adherence rate in MDR-TB patients was 14.3%. The mDST implementation rate was 96.1%. Of the 459 patients who underwent both mDST and pDST, the discordance rate for rifampicin (RIF) resistance was 22.6% (n = 104), of which 72.1% (n = 75) were resistant on mDST but susceptible on pDST. The discrepancy in mDST and pDST results related to RIF resistance was found to be the main cause of non-adherence to new drug regimen.CONCLUSION: Comprehensive training on how to interpret conflicting results between mDST and pDST could enhance the utilisation of new drugs in the treatment of MDR/RIF-resistant TB.

Treatment outcome, recurrence and safety of multidrug-resistant TB treated with low-dose linezolid

BACKGROUND: Linezolid (LZD) is a key treatment option for patients with multidrug-resistant/rifampicin-resistant TB (MDR/RR-TB). We investigated the long-term treatment outcomes and safety of MDR/RR-TB treatment using low-dose LZD.METHODS: Medical records of patients with MDR/RR-TB treated with LZD ≥4 weeks between 2004 and 2018 at the Asan Medical Center, Seoul, Republic of Korea, were reviewed. Standard-dose and low-dose LZD groups were defined as patients initially administered LZD ≥600 mg/day or 300 mg/day, respectively.RESULTS: Among 94 patients, 65 were included in the low-dose LZD group; mean age was 43.1 ± 15.6 years, 53 (56.4%) were men and 77 (83.7%) were resistant to fluoroquinolone. The low-dose LZD group showed features of less severe disease, such as limited MDR-TB history and less severe radiological findings. There was no difference in treatment outcomes, relapse and safety between groups. In the low-dose LZD group, 54 (83.1%) succeeded treatment, of whom 48 (88.9%) were followed-up for a median of 38 months; there was no recurrence. Adverse drug reactions were reported in 41 (63.1%); peripheral neuropathy was most frequently reported (n = 31, 47.7%), while myelosuppression was reported in 12 (18.5%).CONCLUSION: Low-dose LZD in selected patients with less severe disease is both effective in the long-term and safe for the treatment of MDR/RR-TB.

Treatment outcomes of multidrug-resistant TB with selective use of new drugs

SETTING: This was a nationwide cohort study.OBJECTIVE: To assess the treatment outcomes in patients with multidrug-resistant TB (MDR-TB) who underwent treatment guided by a national TB expert review committee in South Korea.DESIGN: We enrolled all patients with MDR-TB submitted for approval for the use of new TB drugs, including bedaquiline and delamanid, from 2016 to 2019. Patients were classified into two groups: those on new TB drugs and those not on new TB drugs. We compared the final treatment outcomes between the groups and analysed the prognostic factors.RESULTS: Of a total of 785 patients, respectively 754 (96.1%) and 31 (3.9%) were classified into the "new TB drugs" group and "no new TB drugs" group. The new TB drugs group had a higher acid-fast bacilli smear positivity rate and higher resistance rate to second-line injectable drugs or fluoroquinolones. Of all the patients, 97.8% achieved culture conversion (97.7% vs. 100%), and 80.4% achieved treatment success (80.2% vs. 86.7%); there was no difference between the two groups.CONCLUSIONS: New drugs are currently recommended for use in all MDR-TB treatment regimens, and the use of new drugs, as determined by an expert committee, in mainly quinolone-susceptible MDR-TB, did not compromise the treatment success rate.

Treatment outcomes in multidrug-resistant tuberculosis according to pyrazinamide susceptibility

BACKGROUND: Pyrazinamide (PZA) is an important anti-tuberculosis drug for multidrug-resistant tuberculosis (MDR-TB). However, PZA has recently been demoted within the hierarchy of TB drugs used for MDR-TB.METHODS: We conducted a retrospective cohort study to investigate treatment outcomes for simple MDR-TB (susceptible to both second-line injectable drugs and fluoroquinolones) according to PZA susceptibility.RESULTS: Among 216 pulmonary MDR-TB patients included in the study, 68 (31.5%) were PZA-resistant (PZA-R). The mean age was 41.8 years, and 63.4% were male. Baseline characteristics such as comorbidity, previous TB history, acid-fast bacilli (AFB) smear positivity and cavitation were similar in PZA-susceptible (PZA-S) and PZA-R patients. The number of potentially effective drugs was slightly higher among PZA-S patients than among the PZA-R (5.1 vs. 4.8, respectively; P = 0.003). PZA was more frequently used in PZA-S patients (73.0%) than in the PZA-R (14.7%), while para-aminosalicylic acid was more frequently used in PZA-R than in PZA-S patients (76.5% vs. 50.7%). The treatment success rate was similar in PZA-S (77.7%) and PZA-R (75.0%) patients. PZA resistance was not associated with treatment success in multivariate analysis.CONCLUSIONS: PZA-resistant simple MDR-TB patients had the same treatment success rate as the PZA-susceptible group even without using novel anti-TB drugs.

First Report of the Korean Lung Transplantation Registry

BACKGROUND

The Korean Organ Transplantation Registry (KOTRY) began to register lung transplants in 2015. This is an initial report on the status of patients receiving lung transplants over the past 2 years.

METHODS

We analyzed a total of 69 patients who received lung transplants in 2015 and 2016 and who registered with the KOTRY.

RESULTS

The 69 patients were treated in 5 institutions. The average (SD) donor age was 39.2 (12.6) years; there were 40 male patients. The average (SD) recipient age was 55.7 (10.0) years, and the number of male recipients was 46. A total of 66 patients underwent bilateral lung transplantation, 3 underwent single-lung transplantation, and 1 underwent simultaneous heart-lung transplantation. The most frequent indication for lung transplantation was idiopathic pulmonary fibrosis (35 patients), followed by connective tissue disease-related interstitial lung disease (9) and acute respiratory failure (8). Prior to transplantation, 23 patients required ventilator care, and 12 required extracorporeal membrane oxygenation while on the waiting list. Episodes of acute rejection during follow-up were reported in 4, 2, 1, and 1 patients at 3, 6, 9, and 12 months, respectively. Infections requiring hospitalization were reported in 27, 10, 4, and 3 patients at 3, 6, 9, and 12 months, respectively.

CONCLUSION

The establishment of KOTRY renders it possible to collect nationwide data on lung transplantation, improving research on the topic and clarifying clinical feasibility.

Subspecies distribution and macrolide and fluoroquinolone resistance genetics of Mycobacterium abscessus in Korea

BACKGROUND

Treating Mycobacterium abscessus infections with antimicrobials remains difficult, possibly due to drug resistance.

OBJECTIVE

To investigate the subspecies distribution of M. abscessus and its correlation with antibiotic susceptibility and the genetics of antibiotic resistance, focusing on macrolides and fluoroquinolones, in the Republic of Korea.

DESIGN

A total of 53 M. abscessus isolates were identified to the subspecies level by sequencing of hsp65 and erm(41). The minimal inhibitory concentrations (MICs) of clarithromycin (CLM) and ciprofloxacin (CFX) were determined using Sensititre™ RAPMYCO plates. The rrl, gyrA and gyrB genes were sequenced to elucidate the molecular mechanisms of macrolide and fluoroquinolone resistance.

RESULTS

Isolates included 22 M. abscessus subsp. abscessus and 31 M. abscessus subsp. bolletii. erm(41) sequences showing subspecies-specific deletions and sequence variations in the 28th nucleotide were concordant with inducible CLM resistance; however, mutations in rrl were not detected. Low- and high-level CFX resistance was observed in respectively 19 (35.8%) and 10 (18.9%) of the 53 clinical isolates, regardless of subspecies. However, no non-synonymous mutations were detected in gyrA or gyrB.

CONCLUSION

Sequencing of the erm gene and subspeciation of M. abscessus may be used to predict inducible macrolide susceptibility. Further studies of the relationship between specific mutations in gyrA or gyrB to MIC change are required.

Conventional and real-time PCR targeting 16S ribosomal RNA for the detection of Mycobacterium tuberculosis complex

SETTING

Conventional diagnostic methods for tuberculosis (TB) have limited sensitivity and specificity or are time-consuming.

OBJECTIVE

16S rDNA and 16S rRNA of Mycobacterium tuberculosis complex (MTC) were used as targets to develop sensitive and specific polymerase chain reactions (PCRs) to improve the diagnosis of MTC.

DESIGN

We developed conventional and real-time PCRs targeting 16S rDNA and rRNA of MTC.

RESULTS

PCRs targeting 16S rRNA had a 10-100 times lower limit of detection for M. tuberculosis than PCRs targeting 16S rDNA. The sensitivities of the 16S rDNA PCR, 16S rRNA reverse transcription PCR (RT-PCR), 16S rDNA real-time PCR and 16S rRNA real-time RT-PCR for sputum specimens were respectively 92%, 94.6%, 96% and 100%. Real-time PCR showed no cross-reactivity, but conventional PCR had cross-reactivity to M. avium, M. gastri and M. nonchromogenicum.

CONCLUSION

PCRs targeting the 16S rRNA of MTC were more sensitive than those targeting 16S rDNA; 16S rRNA real-time RT-PCR showed the highest sensitivity and specificity for MTC.

Comparison of LTBI treatment regimens for patients receiving anti-tumour necrosis factor therapy

SETTING

A tertiary referral centre in South Korea.

OBJECTIVE

To compare the completion rates and adverse drug reactions of three latent tuberculous infection (LTBI) treatment regimens for patients receiving anti-tumour necrosis factor (anti-TNF) therapy.

DESIGN

A total of 408 patients were diagnosed with LTBI before receiving anti-TNF therapy between December 2004 and December 2013. Nine months of isoniazid (9H), 4 months of rifampicin (4H) or 3 months of isoniazid/rifampicin (3HR) were prescribed. The results were analysed retrospectively.

RESULTS

The mean age of the 408 study subjects was 44 years; 258 (63.2%) were male. The 9H, 4R and 3HR treatment regimens were given to respectively 61 (15.0%), 139 (34.1%) and 208 (51.0%) patients. A total of 362 (88.7%) patients completed the treatment. The treatment completion rate was highest in patients receiving 3HR (94.2%). Of the 408 patients, 54 (13.2%) had one or more adverse drug reactions; their frequency was similar in the three groups.

CONCLUSIONS

In patients receiving anti-TNF therapy, 3HR seems to be the most acceptable treatment regimen for LTBI, given its high completion rate and acceptable rate of adverse drug reactions.

The 'either test positive' strategy for latent tuberculous infection before anti-tumour necrosis factor treatment

SETTING

A ttertiary referral centre in South Korea.

OBJECTIVES

The 'either test positive' strategy, incorporating both the tuberculin skin test (TST) and the T-SPOT(®).TB(T-SPOT) assay, was evaluated as a novel method for diagnosing latent tuberculous infection (LTBI) before treatment with anti-tumour necrosis factor (TNF) in patients with immune-mediated inflammatory diseases.

DESIGN

From June 2008 to April 2012, 430 patients received anti-TNF treatment at our institution. TST and T-SPOT were performed simultaneously at baseline. LTBI was defined as a positive TST or a positive T-SPOT result.

RESULTS

The positivity rates for the TST and T-SPOT assays were respectively 19.1% (82/430) and 44.2% (190/430), yielding an LTBI-positive rate of 48.6% (209/430). LTBI treatment was initiated in 46.0% (198/430) of patients and was completed by 89.4% (177/198). During follow-up (median 884 days), 0.9% (4/430) of the patients developed active tuberculosis (TB). All four TB patients were TST-negative at baseline, although two received LTBI treatment based on the baseline positive T-SPOT assay results.

CONCLUSIONS

The either test positive strategy is a valid method for diagnosing LTBI before anti-TNF treatment, although it is not clear whether it is superior to other strategies.

Treatment outcomes and moxifloxacin susceptibility in ofloxacin-resistant multidrug-resistant tuberculosis

SETTING

A tertiary referral centre in Seoul, South Korea.

OBJECTIVE

To investigate the effect of moxifloxacin (MFX) susceptibility and later-generation fluoroquinolone (FQ) use on the treatment outcomes of ofloxacin (OFX) resistant multidrug-resistant tuberculosis (MDR-TB).

DESIGN

Of 223 patients diagnosed with MDR-TB between January 2006 and December 2012, 70 (31.4%) patients with OFX-resistant MDR-TB were enrolled in this retrospective cohort study. Their treatment outcomes were analysed.

RESULTS

The mean age (standard deviation) of the 70 patients was 40.6 (12.9) years; 43 (61.4%) were male and 26 (37.1%) had extensively drug-resistant TB. Of the 70 patients, 22 (31.4%) had MFX-susceptible TB, while the remaining 48 (68.6%) were MFX-resistant. The MFX-susceptible and -resistant groups were comparable in terms of baseline characteristics (including age, sex and radiological severity), and respectively 90.9% (20/22) and 70.8% (34/48) were treated with later-generation FQ-containing regimens (P = 0.074; mainly MFX [40/54, 74.1%]). Treatment success was achieved in 72.7% (16/22) of the MFX-susceptible patients and in 41.7% (20/48) of the MFX-resistant patients (P = 0.021). Treatment failure was significantly higher in the MFX-resistant group (41.7% [20/48] vs. 9.1% [2/22]; P = 0.006).

CONCLUSION

Patients with OFX-resistant MDR-TB had significantly better treatment outcomes when susceptible to MFX. This probably reflects the effect of later-generation FQ treatment.

GenoType® MTBDRplus assay detection of drug-resistant tuberculosis in routine practice in Korea

SETTING

Korea is an intermediate-burden country with high rates of tuberculosis (TB) drug resistance.

OBJECTIVE

To evaluate the performance of the GenoType® MTBDRplus (MTBDR) assay in diagnosing drug-resistant TB in routine practice in Korea.

DESIGN

The MTBDR assay was performed on 428 samples, and the results were retrospectively compared with the results of conventional drug susceptibility testing (DST). The interval between treatment and diagnosis of drug resistance was also compared.

RESULTS

The sensitivity, specificity and positive and negative predictive values of the MTBDR assay were respectively 96.6%, 98.9%, 93.4% and 99.5% for the detection of rifampicin (RMP) resistance; 93.8%, 98.3%, 92.7% and 98.6% for isoniazid (INH) resistance; and 91.1%, 99.2%, 99.4% and 98.7% for multidrug-resistant TB (MDR-TB). The median interval between the start of anti-tuberculosis chemotherapy and the reporting of results was 88.9 days for conventional DST and 19.8 days for MTBDR using clinical specimens.

CONCLUSION

The specificity of the MTBDR assay in detecting MDR-TB was very high, although the sensitivity in detecting INH resistance and MDR-TB was not optimal (<95%). Although the turnaround time in detecting drug resistance was dramatically reduced with MTBDR compared to conventional DST, more effort is needed to shorten the turnaround time.

CT findings of pulmonary non-tuberculous mycobacterial infection in non-AIDS immunocompromised patients: a case-controlled comparison with immunocompetent patients

OBJECTIVE

To describe CT findings of non-tuberculous mycobacteria (NTM) pulmonary infection in non-AIDS immunocompromised patients (ICPs) and to compare these findings with those in immunocompetent patients.

METHODS

From July 2000 to August 2007, 369 patients (mean age 58.3 years; 169 males and 200 females) with pulmonary NTM infection were retrospectively reviewed. Of these 369 patients, 24 ICPs (mean age 64.8 years; 15 males and 9 females) were identified. 16 patients had diabetes mellitus, and 6 patients had received long-term steroid therapy. One had received solid organ transplantation and one had received high-dose chemotherapy for haematological disease. 24 age- and sex-matched immunocompetent patients (mean age 64.6 years; 15 males and 9 females) were selected as the control group from the same registry. CT images were reviewed in consensus by three chest radiologists, who were blinded to immune status. Each lung lobe was evaluated in terms of extent of the lesion, bronchiectasis, parenchymal opacity and the presence of ancillary findings. results: A total of 287 lobes were evaluated in ICPs and the control group. The ICPs showed a higher prevalence of ill-defined nodules, with cavities and large opacity >2 cm with/without cavity (p=0.03, 0.04 and 0.02, respectively). Regardless of the immune status, the most common CT findings were bronchiectasis and ill-defined nodules without cavity.

CONCLUSION

The most common CT findings of pulmonary NTM infection in ICPs were bronchiectasis and ill-defined nodules, similar to those in the control group. Ill-defined nodules with cavity and large opacity >2 cm with/without cavity were more frequently found in ICPs.

ADVANCES IN KNOWLEDGE

In patients affected by NTM infection, large opacities and cavitation in pulmonary nodules are more frequent in ICPs than in immunocompetent patients.

Diagnostic sensitivity of culture and drug resistance patterns in Korean patients with intestinal tuberculosis

SETTING

It is challenging to differentiate between intestinal tuberculosis (ITB) and Crohn's disease in areas where TB is still prevalent. The use of diagnostic tools and verifying the drug resistance patterns of ITB can be helpful for its correct diagnosis.

OBJECTIVE

To determine the diagnostic sensitivity of a culture assay using colonoscopic biopsy specimens and the drug resistance patterns of Mycobacterium tuberculosis isolated from ITB.

DESIGN

Data from 400 patients diagnosed with ITB were retrospectively analysed.

RESULTS

Of the 400 patients, 170 (42.5%) were males; the median age at diagnosis was 40 years. The sensitivity of culture was 44.1% (145/329). Resistance to at least one anti-tuberculosis drug was identified in 13 (17.6%) and multidrug-resistant TB (MDR-TB) was diagnosed in two (2.7%) of the 74 patients for whom drug susceptibility testing was performed. Including M. tuberculosis isolated from respiratory specimens, the proportion of MDR-TB was 4.4% (5/113); previous anti-tuberculosis treatment was an independent risk factor for MDR-TB (26.7% vs. 1.0%, P < 0.01).

CONCLUSION

Culture of colonoscopic biopsy specimens shows substantial diagnostic sensitivity; the frequency of MDR-TB is higher in previously treated cases than in new cases.

Distinguishing tuberculosis from Mycobacterium avium complex disease using an interferon-gamma release assay

SETTING

The QuantiFERON-TB Gold (QFT-G) test can be used to distinguish between tuberculosis (TB) and non-tuberculous mycobacterial disease, but a high background TB infection rate may pose a problem. Although the QuantiFERON-TB (QFT) test, the first-generation QFT-G test, employs a non-specific PPD antigen, avium sensitin is also used as a stimulating antigen.

OBJECTIVE

To evaluate the utility of these two interferon gamma release assays (IGRAs), QFT-G and QFT, and the tuberculin skin test (TST), to differentiate TB from Mycobacterium avium complex (MAC) disease in an intermediate TB burden country.

METHODS

We compared the diagnostic performance of these three tests in 38 prospectively enrolled patients with TB and 40 with MAC lung disease.

RESULTS

The TST yielded positive results in 70.6% of TB and 47.5% of MAC patients; the proportions were respectively 89.5% and 34.3% for QFT-G and 86.8% and 35.3% for QFT. The three tests were of similar accuracy, sensitivity and specificity in diagnosing TB.

CONCLUSION

Our findings indicate that the TST and IGRAs could not discriminate between active TB and MAC disease or latent TB infection in a TB-endemic area.

Non-tuberculous mycobacterial diseases presenting as solitary pulmonary nodules

SETTING

South Korea, 2005-2007.

BACKGROUND

Non-tuberculous mycobacterial diseases presenting as solitary pulmonary nodules (NTM-SPN) are rare and may be misdiagnosed as tuberculoma.

DESIGN

Eleven NTM-SPN patients were enrolled retrospectively and compared with two groups each of 33 patients with upper lobe cavitary (UC) and nodular bronchiectatic (NB) type NTM diseases, respectively.

RESULTS

The patients' median age was 52 years. Compared with UC-type disease, NTM-SPN patients showed female (n = 9) and never smoker (n = 8) predominance and fewer comorbidities (n = 0; P < 0.05 for each). Mycobacterium avium (n = 9) was predominant in NTM-SPN patients, followed by M. intracellulare (n = 2), whereas M. intracellulare was most frequently isolated from patients with both UC- and NB-type NTM (P < 0.05). The nodules were a median of 2.3 cm in diameter (range 1.6-6.3 cm) and were distributed evenly in all lobes. In all patients, percutaneous needle aspiration/biopsy was performed with a median 71 days of diagnostic delay. Ten patients successfully completed treatment, and one showed spontaneous reduction of nodule size without treatment. Reverse blot hybridisation assays of six DNA samples identified four subjects with M.avium-intracellulare complex (MAC), in line with conventional test data.

CONCLUSION

NTM-SPN was caused exclusively by MAC. Although clinical outcome was favourable, confirmatory diagnosis was delayed. Molecular methods are needed for early diagnosis of NTM-SPN.

Living-donor liver transplantation in patients with concurrent active tuberculosis at transplantation

SETTING

Although active tuberculosis (TB) is a contraindication for liver transplantation (LT), LT may be the only possible treatment option in patients with irreversible liver failure and concurrent TB.

OBJECTIVES

To assess the outcome of LT in patients with concurrent TB and liver failure.

METHODS

We retrospectively evaluated the clinical outcomes of nine LT recipients with concurrent TB in Korea, an intermediate TB burden country.

RESULTS

The primary causes of living-donor LT (LDLT) in nine patients were anti-tuberculosis drug-induced fulminant hepatic failure (n = 4) and end-stage liver disease (n = 5). The sites of active TB were the lungs (n = 5), lymph nodes (n = 3) and pleura (n = 1). After LDLT, most patients were treated with less hepatotoxic drugs, including fluoroquinolones, ethambutol and cycloserine; none was treated with pyrazinamide. One patient experienced acute rejection, probably attributable to an interaction between rifampicin and cyclosporine. All nine patients, including one taking rifabutin, successfully completed anti-tuberculosis treatment and have been followed up for a median of 926 days after LDLT, without relapse of TB.

CONCLUSION

When properly managed, the prognosis of LDLT recipients with concurrently active TB at transplantation is very favourable. The current protocol, which considers active TB an absolute contraindication for LT, should be modified or relaxed, particularly for patients with LDLT.

Combined use of QuantiFERON-TB Gold assay and chest computed tomography in a tuberculosis outbreak

OBJECTIVE

To evaluate the value of the QuantiFERON-TB Gold (QFT-G) assay and chest computed tomography (CT), in addition to the conventional use of the tuberculin skin test (TST) and chest radiography (CXR), in a contact investigation of a tuberculosis (TB) outbreak.

DESIGN

In a contact investigation of a TB outbreak in a high school, TST and CXR were performed on all 1044 employees and students. QFT-G was performed on TST-positive subjects, and CT on QFT-G-positive subjects and students with TST > or =20 mm.

RESULTS

TST was positive in 388 subjects (37.2%), while QFT-G was positive in 7.6% (30/394). CXR showed abnormal findings suggestive of TB in 10 (1.0%) subjects, all of whom were TST-positive and six of whom were QFT-G-positive. Findings suggestive of active TB were noted in 17 (32.7%) of 52 subjects by CT. Collectively, among 21 (1.1%) TB patients, all were TST-positive, 12 (57.1%) were QFT-G-positive and active TB was diagnosed by CT, and not by CXR, in 11 subjects.

CONCLUSION

Compared to the conventional approach, the additional use of QFT-G in TST-positive subjects and chest CT in subgroups with a high probability of infection was found to be more effective in the differentiation between active TB, latent TB and non-infected subjects in a contact investigation.

Clinical course and lung function change of idiopathic nonspecific interstitial pneumonia

Most studies of idiopathic nonspecific interstitial pneumonia (NSIP) have primarily studied mortality. In order to clarify the detailed outcome and prognostic markers in idiopathic NSIP, the clinical course with initial radiological and clinical features was analysed. The clinical course of 83 patients who were classified with idiopathic NSIP (72 fibrotic, 11 cellular; 27 males and 56 females; mean+/-sd age 54.4+/-10.1 yrs) was retrospectively analysed. In fibrotic NSIP, 16 (22%) patients died of NSIP-related causes with a median (range) follow-up of 53 (0.3-181) months. Despite the favourable survival (5-yr 74%), patients with fibrotic NSIP were frequently hospitalised with recurrence rate of 36%. Reduced forced vital capacity at 12 months was a predictor of mortality. On follow-up, lung function was improved or stable in approximately 80% of the patients. The extent of consolidation and ground-glass opacity on initial high-resolution computed tomography correlated significantly with serial changes of lung function, and the presence of honeycombing was a predictor of poor prognosis. During follow-up, eight (10%) patients developed collagen vascular disease. In conclusion, the overall prognosis of fibrotic nonspecific interstitial pneumonia was good; however, there were significant recurrences despite initial improvement and a subset of the patients did not respond to therapy. Some patients developed collagen vascular diseases at a later date.

Pulmonary tuberculosis with acute respiratory failure

The aim of the present study was to evaluate the clinical characteristics, prognoses and predictors of mortality of patients with pulmonary tuberculosis (TB) with acute respiratory failure (ARF), and to investigate the adjunctive use of corticosteroids in such cases. TB patients with ARF requiring mechanical ventilation (n = 90) were enrolled retrospectively during 1989-2006. The patients were divided into two groups: tuberculous pneumonia (TBP; n = 66), and miliary TB (MTB; n = 24). The TBP patients were older than the MTB patients (mean age 68.0 versus 54.5 yrs), and the mean+/-SD interval from hospital admission to start of anti-TB treatment was longer for the TBP than for the MTB group (5.0+/-7.0 versus 2.8+/-2.5 days). However, there was no difference in in-hospital mortality rate between the two groups (68.2 versus 58.3%). In the TBP patients, multivariate analysis showed that advanced age and shock unrelated to sepsis were associated with poor outcomes. Even though corticosteroid use was a predictor of survival in TBP patients, it was difficult to conclusively determine the efficacy of corticosteroids in TBP with ARF because of the retrospective study design. The present study reveals the need for randomised controlled trials to clarify the role of corticosteroids as adjunctive therapy in the management of tuberculous pneumonia with acute respiratory failure.

Incidence of tuberculosis among health care workers at a private university hospital in South Korea

SETTING

A private university hospital in South Korea.

OBJECTIVE

To investigate the incidence of tuberculosis (TB) among health care workers (HCWs) employed at a university hospital in South Korea.

DESIGN

The occurrence of TB cases among HCWs over a 6-year period (2001-2006) was reviewed. The prevalence of TB was compared with that of the general population using a prevalence ratio (PR) adjusted by age and sex.

RESULTS

The study involved 8433 people. TB developed in 61 HCWs (0.72%). The prevalence ratio among all HCWs was 1.05 (95%CI 0.80-1.35). In occupational subgroups, the PRs for doctors, nurses and employees in other departments were respectively 0.58 (95%CI 0.30-1.01), 1.81 (95%CI 1.21-2.59) and 0.95 (95% CI 0.58-1.46). For nurses working in TB-related departments, the relative risk of developing TB was 3.4 times higher (95%CI 1.52-8.25) than for employees in other departments (P=0.005). The PR for nurses working in TB-related department was 5.1 (95%CI 3.23-8.42).

CONCLUSION

Among HCWs, nurses working in TB-related departments were at increased risk of developing TB. This suggests that some TB develops via in-hospital infection.

Impact of short-term exposure to fluoroquinolones on ofloxacin resistance in HIV-negative patients with tuberculosis

SETTING

Seoul, Korea, a country with an intermediate tuberculosis (TB) burden and low prevalence of human immunodeficiency virus (HIV) infection.

OBJECTIVES

To determine the frequency of ofloxacin (OFX) resistance in Mycobacterium tuberculosis, and to assess whether short-term use of fluoroquinolones (FQNs) induces ofloxacin-resistant M. tuberculosis.

DESIGN

The subject cohort consisted of 2788 patients with culture-confirmed TB with drug susceptibility testing data; only four were HIV-positive. The patients were divided into two groups: those who were or were not recently exposed to FQNs.

RESULTS

Of the 2788 isolates, the rates of OFX resistance were 1.1% and 8.5% in initially treated and retreated patients, respectively (P < 0.05). Of the 94 OFX-resistant isolates, 83 (88.3%) were multidrug-resistant (MDR). There was no difference in rates of OFX resistance throughout the study period, or between the FQN-exposed (1/39, 2.6%) and control groups (93/2749, 3.4%). The median duration of FQN treatment was 7 days (range 1-47 days). One OFX-resistant isolate in the FQN-exposed group was MDR.

CONCLUSION

The rate of OFX-resistant M. tuberculosis was low and stationary throughout the study period in Korea. Most OFX resistance was accompanied by MDR, and the frequency of OFX-resistant M. tuberculosis was low in subjects taking short-term FQNs.

Deep tracheal laceration after balloon dilation for benign tracheobronchial stenosis: case reports of two patients

We report two cases of deep tracheal laceration in female patients after balloon dilation for benign tracheobronchial stenosis. Immediate post-procedure bronchoscopy and CT including 3D reconstructions showed deep lacerations in the posterior tracheal wall. Clinically, the patients' dyspnoea subsided and there has been no recurrence during follow-up after balloon dilation. On the follow-up 3D-reconstructed CT scans obtained 2 months and 8 months following balloon dilation, respectively, the lacerations had healed completely and there was considerable improvement in lumen size.

Comparison of two commercial interferon- assays for diagnosing Mycobacterium tuberculosis infection

The clinical usefulness of ex vivo interferon-gamma assays may largely depend on the assay format and epidemiological status of tuberculosis (TB) in the region studied. From July 2004 to June 2005 a prospective comparison study was undertaken at a tertiary referral hospital in South Korea. The results of tuberculin skin tests (TST) and the commercially available QuantiFERON-TB Gold (QFT-G) and T SPOT-TB (SPOT) assays were compared in an intermediate TB-burden country. Of the 224 participants studied, results from all three tests (TST, QFT-G, and SPOT) were available in 218; 87 with active TB and 131 at a low risk for TB. Using 10 mm as a cut-off for TST, SPOT sensitivity (96.6%) was significantly higher than that seen for TST (66.7%) and QFT-G (70.1%). QFT-G showed superior specificity over TST (91.6 versus 78.6%). Although the specificity of QFT-G was higher than that of SPOT (91.6 versus 84.7%), the difference was not statistically significant. Whilst some differences were found in the performance of the two commercialised interferon-gamma assays, they seemed to be superior in their detection of Mycobacterium tuberculosis infection compared with tuberculin skin tests. The most appropriate choice of interferon-gamma assay to use may depend on the clinical setting.

Toll-like receptor 4 plays no role in susceptibility of mice to Mycobacterium tuberculosis infection

Although various members of the pattern recognition Toll-like receptor (TLR) family have been implicated in host resistance to Mycobacterium tuberculosis infection, it remains unclear if the TLR4 receptor plays an important role. We demonstrate here that infection of TRL4-competent and TLR4-deficient mice on the C3H inbred mouse strain background had similar outcomes, measured in terms of the course of the disease, cell accumulation patterns in the lungs, and lung histopathology. These data argue against a significant role for TLR4 in immunity to tuberculosis in the mouse model.

Cerebral metabolic abnormalities in COPD patients detected by localized proton magnetic resonance spectroscopy

STUDY OBJECTIVES

To investigate changes in the cerebral metabolism of patients with COPD, using localized in vivo proton magnetic resonance spectroscopy ((1)H MRS), and to evaluate the clinical significance of cerebral metabolic abnormalities in COPD patients.

PATIENTS AND METHODS

Seventeen symptomatic COPD patients and 21 age-matched healthy volunteers participated in this study. All subjects underwent (1)H MRS, and neuropsychological tests (Wechsler memory scale-revised [WMS-R], color trail test, and grooved pegboard test) were performed by COPD patients. Magnetic resonance spectra were obtained from localized regions of parietal white matter (PWM) and occipital gray matter (OGM). Absolute levels of N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), and myo-inositol (mI) were calculated.

RESULTS

In COPD patients, the mean (+/- SD) FEV(1) was 38 +/- 10% predicted, the PaCO(2) was 39 +/- 7 mm Hg, and the PaO(2) was 89 +/- 18 mm Hg, and these values did not exhibit statistical correlation with the levels of cerebral metabolites. NAA, Cr, and Cho levels in PWM were all significantly lower in COPD patients than in control subjects (p < 0.0125 [Bonferroni adjusted]). Neuropsychological parameters were lower in COPD patients compared with standardized values. However, they were not correlated with the levels of cerebral metabolites except for a positive correlation between the Cho level in PWM and the general memory quotient of WMS-R (r = 0.52; p < 0.05).

CONCLUSIONS

Our results demonstrate that the cerebral metabolism is significantly altered in symptomatic COPD patients. The relationship between decreased Cho levels and memory dysfunction, and the clinical significance of other cerebral metabolic changes in COPD patients need to be further investigated.

Comparison of the response to the prone position between pulmonary and extrapulmonary acute respiratory distress syndrome

OBJECTIVES

To determine whether the response to the prone position differs between acute respiratory distress syndrome (ARDS) resulting from a pulmonary cause (ARDSp) and that from an extrapulmonary cause (ARD-Sexp).

DESIGN AND SETTING

Prospective observational study in a medical ICU of a university-affiliated hospital.

SUBJECTS

A consecutive series of 31 patients with ARDSp and 16 with ARDSexp within 3 days of onset of ARDS.

INTERVENTION

Prone position for at least 2 h.

MEASUREMENTS AND RESULTS

In ARDSp, compared with the supine position (121 +/- 49 mmHg), PaO2/FIO2 was not increased after 0.5 h but was increased after 2 h in the prone position (158 +/- 60 mmHg). In ARDSexp, compared with the supine position (106 +/- 53 mmHg), PaO2/FIO2 was increased after 0.5 h (155 +/- 91 mmHg), but was not further changed after 2 h. Marked oxygenation response (increase in PaO2/FIO2 > 40% from baseline) after 0.5 h was 23% in ARDSp and 63% in ARDSexp, and that after 2 h was 29% and 63%, respectively. Static respiratory compliance decreased in the prone position in ARDSexp (30 +/- 11 ml/cmH2O at baseline, 27 +/- 11 after 0.5 h and 25 +/- 9 after 2 h) but not in ARDSp. Consolidation score as determined on the first chest radiography taken in the prone position decreased to a greater degree in ARDSexp (-2.4 +/- 4.1) than in ARDSp (0.3 +/- 4.1).

CONCLUSION

Pulmonary ARDS and extrapulmonary ARDS in their early stages respond differently to the prone position with regard to the time course of oxygenation, respiratory mechanical behaviour, and radiographic change. These findings suggest that the early pathophysiology of ARDS differs according to the type of primary insult to the lung.

Pathogenic role of endothelin 1 in hemodynamic dysfunction in experimental acute pulmonary thromboembolism

The plasma endothelin-1 (ET-1) level is elevated in patients with acute pulmonary thromboembolism (APE). Whether ET-1 is a pathogenic mediator or a simple marker of APE is not known. We investigated the role of ET-1 in hemodynamic dysfunction in APE through evaluating the effects of ET(A) receptor antagonist in an experimental APE model. We also examined ET-1 expression in embolized lungs. In a canine autologous blood clot pulmonary embolism model, ET(A) receptor antagonist ZD2574 (10 mg/kg, intravenous; ZD2574 group; n = 6) or vehicle (control group; n = 5) was administered. Hemodynamic and gas exchange parameters and plasma levels of ET-1 were serially measured. Prepro-ET-1 mRNA expression and the distribution of ET-1 peptide in lung tissues were also examined. With ZD2574 pulmonary arterial pressure and pulmonary vascular resistance significantly decreased, and were lower compared with the control group. The decrease in cardiac output was also less in the ZD2574 group. Plasma ET-1 levels increased after embolization. Prepro-ET-1 mRNA expression increased in embolized lungs and ET-1 peptide expression also increased in embolized lungs, particularly in the muscular pulmonary arteries, compared with normal lungs. These findings suggest that ET-1 partially contributes to hemodynamic derangements of APE, and that ET(A) receptor antagonists might constitute a useful therapeutic tool for APE.

The prognosis of respiratory failure in patients with tuberculous destroyed lung

SETTING

The medical intensive care unit of a tertiary referral hospital.

OBJECTIVE

To determine the prognosis of patients whose lungs are damaged by previous and/or present tuberculosis infection and who have subsequently been presented with acute respiratory failure requiring mechanical ventilation.

DESIGN

A consecutive series of 38 patient cases with retrospective data analysis.

RESULTS

Pulmonary function test results for tests performed within the previous year were made available in 21 of the 38 cases (55%). These showed a mean (+/- SD) forced vital capacity (FVC) of 1.52 +/- 0.46 L (41.0 +/- 14.5% predicted), a forced expiratory volume/second (FEV1) of 0.77 +/- 0.18 L (29.3 +/- 13.6% predicted), and an FEV1/FVC ratio of 55.1 +/- 16.2%. The acid-fast bacilli (AFB) positive group had a significantly higher mortality and more severe lung destruction when compared with the AFB-negative group. Patients with positive AFB were significantly more hypocapnic than those with negative AFB (6.4 +/- 2.7 vs. 9.3 +/- 3.9 kPa, P = 0.020). In multivariate analysis, the level of PaCO2 on admission was identified as the only significant prognostic index (OR 0.76, 95%CI 0.60-0.96).

CONCLUSION

Patients with positive AFB smears or cultures may have higher mortality rates than those with negative AFB in the tuberculosis destroyed lung patients with acute respiratory failure. A higher PaCO2 measurement could indicate a better survival rate in this group of patients.

Cigarette smoke extract induces endothelin-1 via protein kinase C in pulmonary artery endothelial cells

We examined the mechanism of endothelin (ET)-1 regulation by cigarette smoke extract (CSE) and the effect of platelets on CSE-induced stimulation of ET-1 gene expression in human and bovine pulmonary artery endothelial cells (PAECs). Our data show that CSE (1%) induces ET-1 gene expression (after 1 h) and ET-1 peptide synthesis (after 4 h) in bovine PAECs. The induction of preproET-1 mRNA level was due to de novo transcription, and new protein synthesis was not required for this induction. The protein kinase C inhibitors staurosporine (10(-8) mol/l) and calphostin C (10(-7) mol/l) abolished the induction of ET-1 gene expression by CSE in bovine and human PAECs. Although a lower concentration of platelets (10(6) cells/ml in bovine PAECs; 10(7) cells/ml in human PAECs) did not significantly alter ET-1 gene expression in PAECs, incubation of platelets with CSE (1%) and PAECs produced a significant increase in preproET-1 mRNA and ET-1 peptide compared with the values in the presence of CSE (1%) alone. CSE (1%) induced platelet aggregation and increased the expression of platelet membrane glycoproteins ex vivo. Thus our data suggest that CSE stimulates ET-1 gene expression via PKC in PAECs. CSE and platelets showed a synergistic effect on ET-1 gene expression, possibly through the activation of platelets by CSE.

Effects of heat pretreatment on histopathology, cytokine production, and surfactant in endotoxin-induced acute lung injury

To determine the effect of heat stress on histopathology of acute lung injury (ALI) caused by administration of lipopolysaccharide (LPS), and to determine the roles of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, interferon (IFN)-gamma, IL-10 and surfactants in heat-induced tolerance to ALI, we administered either saline or LPS (3 mg/kg of body weight) intravenously to male Sprague-Dawley rats without and with heat pretreatment. Five hours after LPS or saline treatment (23 h after heat-pretreatment), samples were obtained. We found that the histopathologic features of LPS-induced ALI were attenuated by heat-pretreatment. Heat-pretreatment did not decrease the elevated plasma or BAL fluid levels of TNF-alpha, IL-1beta, and IFN-gamma by LPS. The plasma level of IL-10 in LPS-treated rats with heat-pretreatment, however, was increased compared to that of LPS-treated rats without heat-pretreatment (P = 0.001). There were no differences in the BAL fluid concentrations of light or heavy density pulmonary surfactant phospholipids depending on heat-pretreatment in LPS-treated rats. These observations suggest that IL-10 might play a role in decreasing LPS-induced acute lung injury after heat-pretreatment.

Mechanistic scheme and effect of "extended sigh" as a recruitment maneuver in patients with acute respiratory distress syndrome: a preliminary study

OBJECTIVE

To devise a new form of sigh ("extended sigh") capable of providing a sufficient recruiting pressure x time, and to test it as a recruitment maneuver in patients with acute respiratory distress syndrome.

DESIGN

Prospective uncontrolled clinical trial.

SETTING

Medical intensive care unit of a university-affiliated hospital.

PATIENTS

Twenty consecutive patients diagnosed with acute respiratory distress syndrome (18 men, 2 women, age 59 +/- 10 yrs).

INTERVENTIONS

From baseline settings of tidal volume (Vt) 8 mL/kg and positive end-expiratory pressure (PEEP) 10 cm H2O on volume control mode with the high pressure limit at 40 cm H2O, the Vt-PEEP values were changed to 6-15, 4-20, and 2-25, each step being 30 secs (inflation phase). After Vt-PEEP 2-25, the mode was switched to continuous positive airway pressure of 30 cm H2O for a duration of 30 secs (pause), after which the baseline setting was resumed following the reverse sequence of inflation (deflation phase). This extended sigh was performed twice with 1 min of baseline ventilation between.

MEASUREMENTS AND RESULTS

Airway pressures and hemodynamic parameters were traced at each step during the extended sigh. Arterial blood gases and physiologic parameters were determined before the extended sigh (pre-extended sigh), at 5 mins after two extended sighs (post-extended sigh), and then every 15 mins for 1 hr. In our average patient, the recruiting pressure x time of the inflation phase was estimated to be 32.8-35.4 cm H2O x 90 secs. Compared with the inflation phase, inspiratory pause pressure of the deflation phase was lower at Vt-PEEP 6-15 (28.9 +/- 2.7 cm H2O vs. 27.3 +/- 2.8 cm H2O) and 4-20 (31.8 +/- 2.9 cm H2O vs. 31.1 +/- 2.9 cm H2O; both p <.05). Compared with pre-extended sigh, Pao2 (81.5 +/- 15.3 mm Hg vs. 104.8 +/- 25.0 mm Hg; p <.001) and static respiratory compliance both increased post-extended sigh (27.9 +/- 7.9 mL/cm H2O vs. 30.2 +/- 9.7 mL/cm H2O; p =.009). Improvement in these parameters was sustained above pre-extended sigh for the duration of the study. Major hemodynamic or respiratory complications were not noted during the study.

CONCLUSION

We present a new form of sigh (i.e., extended sigh) capable of achieving an augmented recruiting pressure x time through a prolonged inflation on a gradually increased end-expiratory pressure. In view of the sustained effect and absence of major complications in our patients, extended sigh could be a useful recruitment maneuver in acute respiratory distress syndrome.

Lung cancer in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) was reported to be associated with increased risk of lung cancer as a result of the occurrence of atypical or dysplastic epithelial changes in fibrosis which progressed to invasive malignancy. In that situation, the cancer will develop in the area of major fibrosis. To investigate the direct relationship between fibrosis and cancer development, the real concordance rate of the two lesions in the chest computed tomography (CT) was analysed and compared to the histological types of lung cancer. The subjects included 63 patients with combined lung cancer and IPF (IPF-CA), 218 patients with lone IPF, and 2,660 patients with primary lung cancer. All patients were diagnosed at Asan Medical Center during the same period. The age, percentage of smokers, and the male sex were significantly higher in IPF-CA compared with lone IPF. The odds ratio of smoking was 2.71 compared to nonsmoking IPF controls. In IPF-CA, 56% of the cancer was located in the periphery of the lung and 52% in the upper lobe. The majority of the cancers (64%) were found in the nonfibrotic area at chest CT. The most frequent cell type was squamous cell carcinoma (35%), and there was no significant difference in the cancer cell type between IPF-CA and total lung cancer population. These findings suggest that in combined lung cancer and idiopathic pulmonary fibrosis patients, the features of the lung cancer are similar to the total lung cancer population.

Nitric oxide and molsidomine in the management of pulmonary hypertension in Takayasu's arteritis

We present three patients with pulmonary hypertension in Takayasu's arteritis who showed long-term favorable response, clinically and hemodynamically, to nitric oxide donor molsidomine. In these patients, nitric oxide inhalation was effective in reducing pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR). Molsidomine (single dose of 4 mg p.o.) was also effective in reducing PAP and PVR, but nifedipine was not. With molsidomine, 4 mg tid, dyspnea, exercise capacity, and hemodynamic parameters were improved. These favorable responses have lasted during the 3-month follow-up period in all patients.

The value of interleukin-12 as an activity marker of pulmonary sarcoidosis

BACKGROUND

Sarcoidosis is characterized by hyperactivity of T-helper lymphocytes and recent studies showed that they were mainly Th1 cells. IL-12 is a major cytokine inducing Th1 differentiation of naive T cells. This study was performed to test whether IL-12 can be a marker for disease activity and possibly a prognosis in sarcoidosis.

METHODS

IL-12 levels of BALF (BALF-IL-12) and conditioned medium of alveolar macrophages (AM) were measured by ELISA in 36 patients with pulmonary sarcoidosis (14 males and 22 females, mean age: 39.6 +/- 11.0 years) and eleven normal controls. Clinically, 16 patients had active sarcoidosis and 20 had an inactive disease.

RESULTS

BALF-IL-12 of sarcoidosis patients (41.3 +/- 43.9 pg/ml) was significantly higher than that of normal controls (2.5 +/- 0.4 pg/ml) (p < 0.001). The patients with active disease (71.3 +/- 54.3 pg/ml) had a higher BAL-IL-12 level than those with inactive disease (17.3 +/- 13.8 pg/ml) (p = 0.0001). It had a significant correlation with the number of T4 cells (p = 0.0001), total cell number, number and percentage of lymphocytes (p = 0.0001) and AM (p = 0.001) in BALF. It was also significantly correlated with soluble ICAM-1 levels in serum (p = 0.0001) and BALF (p = 0.002), and ICAM-1 expression of AM (p = 0.001). Furthermore the patients whose condition worsened without therapy had a significantly higher initial BALF-IL-12 level than the patients whose condition improved spontaneously. The AM of sarcoidosis secreted significantly more IL-12 (133 +/- 177 pg/ml) than AM of controls (68.3 +/- 43.7 pg/ml) (p = 0.038).

CONCLUSION

Our data suggest that the BALF-IL-12 level can be used as a marker of the activity of pulmonary sarcoidosis and possibly prognosis.

Closing volume influences the postural effect on oxygenation in unilateral lung disease

In normal adults, both blood flow and ventilation are distributed preferentially to the dependent lung zones. In adults with unilateral lung disease, arterial oxygenation improves when they are positioned with their good lung down because of improved matching of ventilation and perfusion. When the closing volume is increased, dependent airways are closed during tidal breathing, so that reduced ventilation-perfusion ratio and hypoxia develops and ventilation is preferentially distributed to the upper lung zones. We undertook an observational study on the effects of lateral recumbency on arterial oxygenation in adult patients with unilateral lung disease and tested the hypothesis that oxygenation in lateral recumbency might be influenced by an increase in closing volume. Arterial blood gases were analyzed in the supine, right and left lateral decubitus positions and the AaPO(2) was calculated in 44 randomly selected patients 49.9 +/- 18.7 yr of age with unilateral pneumonia (23 cases) or pulmonary tuberculosis (21 cases). In 26 patients, individual Pa(O(2)) with the normal lung in the dependent position was higher than that with the diseased lung; the opposite was true for 18 patients. The difference in Pa(O(2)) and AaPO(2) between the two positions was statistically significant in both groups. In 16 patients (10 men and six women 49.2 +/- 18.2 yr of age), we measured closing volume and determined the fractional ventilation to each lung by (133)Xe lung scan in the three positions. In these 16 patients, the difference in Pa(O(2)) between the normal and the diseased lung in the dependent position was related significantly to the difference in the fractional ventilation going to the normal lung between the dependent and the supine position (r = 0.642, p = 0. 007). The latter was related significantly to the % predicted closing volume (CV/VC) (r = -0.597, p = 0.015). This study has shown that closing volume, as well as posture, might be involved in determining oxygenation in lateral recumbency in patients with unilateral lung disease.

Tracheobronchial strictures: treatment with a polyurethane-covered retrievable expandable nitinol stent--initial experience

A polyurethane-covered retrievable expandable stent was placed in 13 patients with tracheobronchial strictures. In four patients with benign strictures, the stent was removed with use of a retrieval hook 2-6 months after placement. After stent removal, three of the four patients did not need further treatment. The retrievable stent warrants further investigation in the treatment of tracheobronchial strictures.

Heat shock response decreases endotoxin-induced acute lung injury in rats

OBJECTIVE

Transient whole-body hyperthermia was reported to reduce lung damage in a rat with intra-abdominal sepsis produced by caecal perforation.

METHODOLOGY

In order to determine the effect of heat shock response on acute lung injury induced by endotoxin, which plays a central role in the pathogenesis of sepsis, we instilled either saline or lipopolysaccharide (LPS) intravenously with and without heat pretreatment in rats. The heated rats had their rectal temperature raised to more than 40 degrees C for 13 min 18 h before intravenous administration of saline or LPS.

RESULTS

We found that the lung leak was significantly increased among the rats given LPS intravenously with (median, 0.17; range, 0.15-0.22; n = 10) and without heat pretreatment (0.23; 0.17-0.30; n = 10) compared with those of saline-treated rats (0.13; 0.10-0.14; n = 10) (P < 0.05 in each). However, rats given LPS after heat pretreatment had significantly decreased lung leak index compared with those of LPS-treated rats without heat pretreatment (P < 0.05). Rats administered LPS intravenously showed increased myeloperoxidase activity without heat pretreatment (19.01; 9.34-28.00 U/g; n = 10) compared with that of saline-treated rats (7.09; 4.49-10.56 U/g; n = 5) (P < 0.05) (Fig. 2). Myeloperoxidase activity of the rats treated with LPS with heat pretreatment (5.57; 2.87-8.96 U/g; n = 10) was significantly decreased to the level of normal control compared with that of LPS-treated rats without heat pretreatment (P < 0.05). The levels of heat shock proteins (HSP72) in lung tissue, which were examined by western blot analysis, were increased over baseline levels at 23 h after hyperthermic stress.

CONCLUSIONS

These observations show that brief heat shock response is associated with the induction of HSP72 protein synthesis and attenuated neutrophil recruitment and acute lung leak is induced by endotoxin in rats.

The effect of varying inspiratory to expiratory ratio on gas exchange in partial liquid ventilation

BACKGROUND

In partial liquid ventilation (PLV), the nondependent lung was observed to be inflated first and the dependent lung later. The inflational time difference between the lung regions can lead to maldistribution of tidal gas and inefficient gas bubbling in the slow-inflating region during PLV. In this situation, increasing the inspiratory to expiratory (I:E) ratio of the mechanical ventilator would lessen the heterogeneity of regional ventilation and improve gas exchange possibly to a greater degree than in gas ventilation (GV).

DESIGN AND SETTING

Animal study at the Asan Institute for Life Sciences, Seoul, Korea Subjects: Eighteen rabbits (2.6 +/- 0.5 kg) with acute lung injury by saline solution lavage.

INTERVENTIONS

Three I:E ratios were tried in GV and then in PLV. I:E ratios were changed by adjusting pause (1:2, 1:1, and 2:1; group 1) or by adjusting inspiratory flow rate (1:3, 1:1, and 2:1; group 2).

MEASUREMENTS AND RESULTS

With increasing I:E ratio in all animals, PaO(2)/FIO(2) increased (80 +/- 24, 143 +/- 74, and 147 +/- 88 mm Hg; p = 0.001), and PaCO(2) decreased (74 +/- 15, 66 +/- 16, and 66 +/- 15 mm Hg; p = 0.006). The increases of PaO(2)/FIO(2) from 1:2/1:3 to 1:1 (p = 0.006) and from 1:1 to 2:1 (p = 0.036) were both greater in group 1 than in group 2. PaCO(2) decreased with increasing I:E ratio in group 1, but not in group 2. The change of PaO(2)/FIO(2) by varying the I:E ratio was 49 +/- 65% in PLV and 14 +/- 14% in GV (p = 0.003).

CONCLUSIONS

Extending the I:E ratio, especially by adding pause, improved gas exchange in PLV. Oxygenation in PLV was affected by the I:E ratio to a greater degree than in GV.

Isoniazid resistance and the point mutation of codon 463 of katG gene of Mycobacterium tuberculosis

It has long been known that almost all isoniazid (INH) resistant mycobacteria lose the catalase and peroxidase activities along with reduced or no virulence for guinea pigs. Recently resistance to INH has become known to be associated with mutations of katG gene encoding the HPI (Hydroperoxidase I) type catalase and peroxidase. Among these mutations, the point mutation of codon 463 of katG gene is found frequently, and is suggested as being associated with INH resistance. Therefore we performed this study in order to confirm the correlation between the point mutation of codon 463 of the katG gene and INH resistance of M. tuberculosis in Korea. Fifty isolates, 32 of which were resistant to INH, and 18 of which were sensitive to INH, were selected for this study. We used PCR-SSCP and RFLP analysis to detect the point mutation of the codon 463 of katG gene and confirmed the CGG (arginine) to CTG (leucine) mutation by direct sequencing analysis. Among 32 resistant isolates, 7 isolates (22%) had the same restriction pattern compared with that of the reference strain (H37Rv), and 25 isolates (78%) showed a different restriction pattern. Among 18 sensitive isolates, 7 isolates (39%) had the same restriction pattern compared with that of H37Rv, and 11 isolates (61%) showed a different restriction pattern. These results suggest that the CGG to CTG change of codon 463 of katG gene of M. tuberculosis may be a polymorphism not related with INH resistance.

Relation between ischemic preconditioning and the duration of sustained ischemia

It has been reported that repetitive brief periods of ischemia and reperfusion (ischemic preconditioning, IP) cause a significant reduction in the extent of myocardial necrosis or in the incidence of reperfusion arrhythmias in rat heart. However, recent reports have stated that IP effect is diminished or lost in the canine or bovine heart if ischemia (mostly regional) is sustained for 40 min or longer. The main objective of this study is to assess whether IP provides myocardial protection in prolonged sustained ischemia under the condition of global ischemia in isolated rabbit heart. The hearts were subjected to 10-60 min sustained ischemia (SI) followed by 60 min reperfusion with (IP heart) or without IP (ISCH heart). IP was induced by 4 cycles of 5 min global ischemia and 5 min reperfusion. Left ventricular function (LVF), extent of infarction (EI) and ultrastructural changes were examined. As a whole, the LVF began to recover on reperfusion but there was no significant difference in the functional parameters. However, extracellular Ca2+ concentration was lower in the ISCH hearts (p < 0.05) and the EI was significantly different between the hearts which had received 60 min SI (67% in the ISCH versus 32% in the IP heart, p < 0.01). Ultrastructural changes were homogeneous in the ISCH hearts and became irreversible in accordance with increase of the duration of ischemia, while these changes were heterogeneous and restricted in the IP heart. These results suggest that IP does not attenuate the postischemic dysfunction in prolonged ischemia but it can provide an infarct size-limiting effect and delay ultrastructural changes. This cardioprotective effect may be related to calcium homeostasis.

Quantitative study on the relation between structural and functional properties of the hearts from three different mammals

The ultrastructural quantitative composition of left ventricular cardiac myocytes from isolated Langendorff-perfused hearts was studied in three different mammals (rabbit, guinea pig, and rat). Volume densities of mitochondria, myofibrils, and unspecified cytoplasm were determined using morphometry and were compared to functional parameters including left ventricular developed pressure (LVDP), contractility (dP/dt), heart rate, TTI (tension-time index, an index of oxygen consumption), and relative heart mass (H/B) obtained from these hearts. Each of the mammals was found to possess a very specific and characteristic quantitative composition of cardiac myocyte. Cardiac myocytes contained 26.8% mitochondria and 56.3% myofibrils in rabbits, 25.8% mitochondria and 60.9% myofibrils in guinea pigs, and 27.7% mitochondria and 58.1% myofibrils in rats. The LVDP, contractility, heart rate, and TTI were quite different among species. However, there were close correlations between the mitochondrial volume density and the LVDP (p < 0.05), and between the mitochondrial volume density and the TTI (p < 0.05), in any group of the animals. It is concluded that the mitochondrial volume density is a good indirect indicator of function of cardiac muscle related to oxidative capacity.