Human lung microsomal cytochrome P4501A1 (CYP1A1) activities: impact of smoking status and CYP1A1, aryl hydrocarbon receptor, and glutathione S-transferase M1 genetic polymorphisms.

There are numerous conflicting epidemiological studies addressing correlations between cytochrome P450 1A1 (CYP1A1) genetic polymorphisms and lung cancer susceptibility, with associations plausibly linked to alterations in carcinogen bioactivation. Similarly, correlations between aryl hydrocarbon receptor gene (AHR) codon 554 genotype and CYP1A1 inducibility are controversial. The objective of this study was to determine whether smoking status, and CYP1A1, AHR, and glutathione S-transferase M1 gene (GSTM1) polymorphisms correlate with altered CYP1A1 activities. Lung microsomal CYP1A1-catalyzed 7-ethoxyresorufin O-dealkylation (EROD) activities were much higher in tissues from current smokers (n = 46) than in those from non-/former smokers (n = 24; 12.11 +/- 13.46 and 0.77 +/- 1.74 pmol/min/mg protein, respectively, mean +/- SD; P < 0.05). However, EROD activities in lung microsomes from current smokers CYP1A1*1/1 (n = 33) and heterozygous MspI variant CYP1A1*1/2A (n = 10) were not significantly different (12.23 +/- 13.48 and 8.23 +/- 9.76 pmol/min/mg protein, respectively, P > 0.05). Three current smokers were heterozygous variant CYP1A1*1/2B (possessing both *2A and *2C alleles), and exhibited activities similar to individuals CYP1A*1/1. One current smoker was heterozygous variant CYP1A1*4 and exhibited activities comparable with individuals CYP1A1*1/1 at that locus. EROD activities in microsomes from current smokers AHR(554)Arg/Arg (n = 41) and heterozygous variant AHR(554)Arg/Lys (n = 5) were not significantly different (12.13 +/- 13.56 and 12.01 +/- 14.23 pmol/min/mg protein, respectively; P > 0.05). Furthermore, microsomal EROD activities from current smokers with the GSTM1-null genotype (n = 28) were not significantly different from those (n = 18) carrying at least one copy of GSTM1 (12.61 +/- 14.24 and 11.34 +/- 12.53 pmol/min/mg protein, respectively; P > 0.05). Additionally, when genotypic combinations of CYP1A1, AHR, and GSTM1 were assessed, there were no significant effects on EROD activity. On the basis of microsomal enzyme activities from heterozygotes, CYP1A1*1/2A, CYP1A1*1/2B, CYP1A1*1/4, and AHR(554) Arg/Lys variants do not appear to significantly affect CYP1A1 activities in human lung, and we observed no association between CYP1A1 activity and the GSTM1-null polymorphism.

Who should follow up lung cancer patients after operation?

BACKGROUND: It is unclear whether follow-up by a thoracic surgeon after lung cancer resection alters survival. METHODS: The charts of 245 early stage (< or = IIB) non-small cell lung cancer patients, diagnosed between 1988 and 1995, were reviewed. Follow-up data were complete to January 1, 1997, in 96.3% (236 of 245) of cases. RESULTS: Ninety of the 111 recurrences were detected before discharge from the thoracic clinic. Despite clinic follow-up, 66.7% (60 of 90) were identified by the family physician, and only 28.9% (26 of 90) by the surgeon. The remaining 4.4% (4 of 90) were detected by other physicians. Ninety-six percent (25 of 26) surgeon-detected recurrences had suspicious clinical or chest radiographic findings, compared with 92% for family physician-detected recurrences (55 of 60; not significant). The cost per recurrence detected by surgeons was Can $4,367. A 75% cost savings could ensure if patients were followed up by their family physician. There was no 5-year survival benefit for patients whose recurrence was detected by the surgeon. CONCLUSIONS: Long-term follow-up after limited-stage non-small cell lung cancer resection could possibly be performed by a family physician alone without compromising overall survival, and with significant cost savings.

Glutathione S-transferase-catalyzed conjugation of bioactivated aflatoxin B(1) in human lung: differential cellular distribution and lack of significance of the GSTM1 genetic polymorphism.

Epidemiological studies suggest that aflatoxin B(1) (AFB(1)), a mycotoxin produced by certain Aspergillus species, may play a role in human respiratory cancers in occupationally-exposed individuals. AFB(1) requires bioactivation to the corresponding exo-8,9-epoxide for carcinogenicity, and glutathione S-transferase (GST)-catalyzed conjugation of the epoxide with glutathione (GSH) is a critical determinant of susceptibility to AFB(1). Of the purified human GST enzymes studied, the polymorphic hGSTM1-1 has the highest activity towards AFB(1) exo-epoxide. The influence of the GSTM1 polymorphism on AFB(1)-GSH formation, as well as the abilities of cytosols from preparations enriched in different isolated lung cell types to conjugate AFB(1)-epoxides, were examined. In whole-lung cytosols from patients undergoing clinically indicated lobectomy, GSTM1 genotype correlated with GSTM1 phenotype as determined by [(3)H]trans-stilbene oxide conjugation: GSTM1-positive = 295 +/- 31 pmol/mg/h (n = 6); GSTM1-negative = 92.8 +/- 23.3 pmol/mg/h (n = 4) (P < 0.05). In contrast, conjugation of microsome-generated [(3)H]AFB(1)-epoxides with GSH was low and variable between patients, and did not correlate with GSTM1 genotype: GSTM1-positive = 11.9 +/- 8.1, 111 +/- 66 and 510 +/- 248 fmol/mg/h (n = 6); GSTM1-negative = 15.3 +/- 16.7, 167 +/- 225 and 540 +/- 618 fmol/mg/h (n = 4) (for 1, 10 and 100 microM [(3)H]AFB(1), respectively). GSH conjugates of AFB(1) exo-epoxide and the much less mutagenic stereoisomer AFB(1) endo-epoxide were produced in a ratio of approximately 1:1 in cytosols from both whole lung and isolated cells. Total cytosolic AFB(1)-epoxide conjugation was significantly higher in fractions enriched in alveolar type II cells (3.07 +/- 1.61 pmol/mg/h) than in unseparated lung cells (0.143 +/- 0.055 pmol/mg/h) or fractions enriched in alveolar macrophages (0. 904 +/- 0.319 pmol/mg/h; n = 4) (P < 0.05). Furthermore, AFB(1)-GSH formation and percentage of alveolar type II cells in different cell fractions were correlated (r = 0.78, P < 0.05). These results demonstrate that human lung GSTs exhibit very low conjugation activity for both AFB(1)-8,9-epoxide stereoisomers, and that this activity is heterogeneously distributed among cell types, with alveolar type II cells exhibiting relatively high activity. Of the GSTs present in human peripheral lung which contribute to AFB(1) exo- and endo-epoxide detoxification, hGSTM1-1 appears to play at most only a minor role.

Biotransformation of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in freshly isolated human lung cells.

Metabolism of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) was characterized in human lung cells isolated from peripheral lung specimens obtained from 12 subjects during clinically indicated lobectomy. NNK biotransformation was assessed in preparations of isolated unseparated cells (cell digest), as well as in preparations enriched in alveolar type II cells, and alveolar macrophages. Metabolite formation was expressed as a percentage of the total recovered radioactivity from [5-(3)H]NNK and its metabolites per 10(6) cells per 24 h. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was the major metabolite formed in all lung cell preparations examined, and its formation ranged from 0.50 to 13%/10(6) cells/24 h. Formation of alpha-carbon hydroxylation end-point metabolites (bioactivation) and pyridine N-oxidation metabolites (detoxification), ranged from non-detectable to 0.60% and from non-detectable to 1.5%/10(6) cells/24 h, respectively, reflecting a large degree of intercellular and inter-individual variability in NNK metabolism. Formation of the alpha-hydroxylation end-point metabolite 4-hydroxy-1-(3-pyridyl)-1-butanol (diol) was consistently higher in alveolar type II cells than in cell digest or alveolar macrophages (0.0146 +/- 0.0152, 0.0027 +/- 0.0037 and 0.0047 +/- 0.0063%/10(6) cells/24 h, respectively; n = 12; P < 0.05). SKF-525A was used to examine cytochrome P450 contributions to the biotransformation of NNK. SKF-525A inhibited keto reduction of NNK to NNAL by 85, 86 and 74% in cell digest, type II cells, and macrophages, respectively (means of 11 subjects, P < 0.05). Type II cell incubates treated with SKF-525A formed significantly lower amounts of total alpha-hydroxylation metabolites compared with type II cells without SKF-525A (0.0776 +/- 0.0841 versus 0.1694 +/- 0. 2148%/10(6) cells/24 h, respectively; n = 11; P < 0.05). The results of this first study examining NNK biotransformation in freshly isolated human lung cells indicate that NNK metabolism is subject to a large degree of inter-individual and intercellular variability, and suggest a role for P450s in human lung cell NNK metabolism. Both alveolar type II cells and alveolar macrophages may be potential target cells for NNK toxicity based on their alpha-carbon hydroxylation capabilities. In addition, carbonyl reduction of NNK to NNAL is SKF-525A sensitive in human lung cells.

Does percutaneous fine-needle aspiration biopsy aid in the diagnosis and surgical management of lung masses?

OBJECTIVES: To evaluate the ability of percutaneous, transthoracic fine-needle aspiration biopsy (FNAB) to correctly diagnose intrathoracic masses, to determine what complications were experienced and at what rate they occurred and to define more clearly the role of this technique in the surgical management of lung masses. DESIGN: A chart review. SETTING: Kingston General Hospital, Kingston, Ont., a tertiary care centre and university-affiliated teaching hospital. PATIENTS: One hundred and thirteen patients who underwent 117 percutaneous transthoracic FNABs between Jan. 1, 1991, and July 1, 1996. OUTCOME MEASURES: Patient demographics, size and location of the lesion, diagnostic result of FNAB, complications of the procedure, smoking history, number of needle passes made by the radiologist and results of any other available biopsy (i.e., through bronchoscopy, mediastinoscopy, pleuroscopy) and of surgical resection, as well clinical information pertaining to the disease state in patients with nondiagnostic or negative FNAB. RESULTS: Eighty-six masses (73.5%) were diagnosed as malignant, 31 biopsy specimens (26.5%) were either nondiagnostic or negative for malignancy. Of these specimens, 15 (48.4%) were subsequently shown to be cancer. In 64 biopsies (54.7%), the patient suffered pneumothorax, requiring hospitalization and chest tube insertion in 35 (29.9%) and 24 (20.5%) cases respectively. The size of the lesion was related to both the diagnostic accuracy and the incidence of pneumothorax. CONCLUSIONS: Percutaneous transthoracic FNAB should not be used routinely in the assessment of patients with lung masses who are medically fit to withstand surgery and are free of widespread disease. The results of FNAB do little to modify the course of surgical management in these patients.

Optimal treatment of descending necrotising mediastinitis.

BACKGROUND: Descending necrotising mediastinitis is caused by downward spread of neck infection and has a high fatality rate of 31%. The seriousness of this infection is caused by the absence of barriers in the contiguous fascial planes of neck and mediastinum. METHODS: The recent successful treatment of seven adult patients with descending necrotising mediastinitis emphasises the importance of optimal early drainage of both neck and mediastinum and prolonged antibiotic therapy. The case is also presented of a child with descending necrotising mediastinitis, demonstrating the rapidity with which the infection can develop and lead to death. Twenty four case reports and 12 series of adult patients with descending necrotising mediastinitis published since 1970 were reviewed with meta-analysis. In each case of confirmed descending necrotising mediastinitis the method of surgical drainage (cervical, mediastinal, or none) and the survival outcome (discharge home or death) were noted. The chi 2 test of statistical significance was used to detect a difference between cases treated with cervical drainage alone and cases where mediastinal drainage was added. RESULTS: Cervical drainage alone was often insufficient to control the infection with a fatality rate of 47% compared with 19% when mediastinal drainage was added (p < 0.05). CONCLUSIONS: Early combined drainage with neck and chest incisions, together with broad spectrum intravenous antibiotics, should be considered standard care for this disease.

Biotransformation of aflatoxin B1 in human lung.

In addition to being a potent hepatocarcinogen, aflatoxin B1 (AFB1) is a pulmonary carcinogen in experimental animals, and epidemiological studies have shown an association between AFB1 exposure and lung cancer in humans. This study investigated AFB1 bioactivation and detoxification in human lung tissue obtained from patients undergoing clinically indicated lobectomy. [3H]AFB1 was bioactivated to a DNA binding metabolite by human whole lung cytosols in a time-, protein concentration-, and AFB1 concentration-dependent manner. Cytosolic activation of [3H]AFB1 correlated with lipoxygenase (LOX) activity and was inhibited by the LOX inhibitor nordihydroguaiaretic acid (NDGA; 100 microM), indicating that LOXs were largely responsible for the observed cytosolic activation of AFB1. In whole lung microsomes, low levels of indomethacin inhibitable prostaglandin H synthase (PHS)-mediated [3H]AFB1-DNA binding and cytochrome P-450 (P450)-mediated [3H]AFB1-DNA binding were observed. Cytosolic glutathione S-transferase (GST)-catalyzed detoxification of AFB1-8,9-epoxide, produced by rabbit liver microsomes, was minimal at 1 and 10 microM [3H]AFB1. With 100 microM [3H]AFB1, [3H]AFB1-8,9-epoxide conjugation with reduced glutathione was 0.34 +/- 0.26 pmol/mg/h (n = 10). In intact, isolated human lung cells, [3H]AFB1 binding to cellular DNA was higher in cell fractions enriched in macrophages than in either type II cell-enriched fractions or fractions containing unseparated cell types. Indomethacin produced a 63-100% decrease in [3H]AFB1-DNA binding in macrophages from five of seven patients, while NDGA inhibited [3H]AFB1-DNA adduct formation by 19, 40 and 56% in macrophages from three of seven patients. In alveolar type II cells, NDGA decreased [3H]AFB1-DNA binding by 30-100% in cells from three patients and indomethacin had little effect. SKF525A, an isozyme non-selective P450 inhibitor, enhanced [3H]AFB1 binding to cellular DNA in unseparated cells, macrophages, and type II cells, suggesting that P450-mediated bioactivation of AFB1 is not a major pathway by which AFB1-8,9-epoxide is formed in human lung cells. Overall, these studies suggest that P450 has a minor role in the bioactivation of AFB1 in human lung. Rather, LOXs and PHS appear to be important bioactivation enzymes. Co-oxidative bioactivation of AFB1, in combination with the low conjugating activity displayed by human lung cytosolic GSTs, likely contributes to human pulmonary susceptibility to AFB1.

Blunt extraperitoneal rupture of the right hemidiaphragm: case report.

A case of blunt extraperitoneal rupture of the right hemidiaphragm and an accompanying abnormal hepatobiliary scan that revealed the rupture are presented. Associated major injuries, the fact that right-sided ruptures have less immediate herniation, and plugging of the defect by the liver are difficulties that can be encountered in establishing the diagnosis. Most diagnostic tests are not helpful and about half of these ruptures are found at laparotomy or thoracotomy. All should be closed surgically.

Reduced incidence of severe infection after heart transplantation with low-intensity immunosuppression.

Despite advances in immunosuppressive therapy and prolonged graft and patient survival, infection after heart transplantation remains problematic. From January 1987 through June 1989, 104 heart transplantations were performed in 100 patients. Immunosuppression induction was by antilymphocyte globulin for 7 days, with oral cyclosporine introduced on stabilization of kidney function (day 3). Steroid therapy was rapidly tapered, and azathioprine was added only in cases of positive donor crossmatch or steroid-resistant rejection. No reverse isolation was used. Twenty-two deaths occurred, one from sepsis. Actuarial survival at 6 months, at 1 year, and at 2 years was 85% +/- 4%, 81% +/- 3%, and 75% +/- 4%, respectively. Fifty-four patients had 81 infections, of which 21 were bacterial; 83% of these episodes were treated. Sixty infections were opportunistic (85% viral), and only 23% necessitated treatment. Actuarial infection-free rates (all types necessitating treatment) at 1 month, at 6 months, and at 2 years were 83% +/- 4%, 75% +/- 5%, and 75% +/- 5%, respectively. Of the 100 transplant recipients, 66% were treated with azathioprine; 47 patients (69%) had an infection, whereas only seven (19%) of the patients not receiving azathioprine became infected (p less than 0.00001). Rejection was noted in 66% of patients, with a median time to the first episode of 4 weeks. A low-intensity immunosuppressive regimen has resulted in fewer serious infections, with acceptable graft loss from rejection. Increased infection surveillance is required for the first 30 days postoperatively and after treatment of rejection episodes.

Prolonged preservation of canine lung allografts: the role of prostaglandins.

The role of prostaglandin E1 (PgE1) and prostacyclin in enhancing the ischemic tolerance of single-lung grafts was investigated. Fifteen donor dogs underwent pulmonary artery flushing with 60 mL/kg of 4 degrees C modified Euro-Collins solution; 5 dogs each received a 15-minute infusion of PgE1, prostacyclin, or saline solution before flushing. After 12 hours of storage at 4 degrees C, left lung transplantation was performed in 15 recipient dogs. Measurements were performed after 10 minutes of right pulmonary artery snaring before transplantation, after transplantation, and after 2, 4, and 6 hours of reperfusion. At 6 hours, the oxygen tensions (on 100% O2) were 478 +/- 64, 296 +/- 75, 79 +/- 12, and 71 +/- 23 mm Hg in control (nontransplanted), prostacyclin-, PgE1-, and saline-treated dogs, respectively (p less than 0.05, prostacyclin or control versus saline and PgE1 dogs). Mean pulmonary artery pressures increased within each group during reperfusion, but were not significantly different among groups. Similarly, peak inspiratory pressures and wet weight to dry weight ratios were not significantly different among groups after 6 hours of reperfusion. We conclude that donor pretreatment with prostacyclin is associated with superior oxygen transfer in canine lung allografts after 12 hours of cold storage, transplantation, and 6 hours of reperfusion. In this model, donor pretreatment with PgE1 conferred no benefit to prolonged lung allograft preservation.

The importance of acquired diffuse bronchomalacia in heart-lung transplant recipients with obliterative bronchiolitis.

The results of heart-lung transplantation are improving with increasing experience in postoperative management, but obliterative bronchiolitis may still develop late postoperatively. We have performed 19 heart-lung transplants, with 1-month, 1-year, and 2-year actuarial survival rates of 95% +/- 5%, 84% +/- 8%, and 69% +/- 16%, respectively. Three early recipients died of bronchiolitis, and four patients who were operated on more than 2 years ago are currently being followed up with bronchiolitis. Since August 1988, 13 surviving recipients have undergone serial postoperative bronchoscopies and transbronchial biopsies with topical analgesia. Diffuse bronchomalacia, involving the main bronchi down to the fifth-order bronchi bilaterally, has developed in four patients with bronchiolitis 9 +/- 2 months after the diagnosis of bronchiolitis was confirmed. Pulmonary function tests have revealed a lower ratio of forced expiratory volume in 1 second to forced vital capacity, lower specific airway conductance, and higher airway resistance in heart-lung recipients with bronchomalacia than in patients with bronchiolitis alone. We conclude that diffuse bronchomalacia occurs frequently in heart-lung transplant recipients who have obliterative bronchiolitis. Bronchomalacia worsens the functional airflow obstruction caused by bronchiolitis and may play an important role clinically in the declining respiratory status of heart-lung transplant recipients.

The safety of low-dose prednisone before and immediately after heart-lung transplantation.

Preoperative steroid use has been considered a contraindication to heart-lung as well as lung transplantation. Moreover, most centers delay prednisone administration until 2 to 3 weeks postoperatively until airway healing is secure. We have performed 19 heart-lung transplantations and four single-lung transplantations since 1983. Five recipients (4 heart-lung, 1 single lung) had received prednisone, 5 to 40 mg daily, for 2 to 10 years preoperatively. All recipients were administered prednisone, 0.5 mg/kg daily, starting on postoperative day 1, with a taper to 0.2 mg/kg daily by 4 weeks. Minnesota antilymphocyte globulin (for 10 days), cyclosporine, and azathioprine were also employed. Bronchoscopy, lavage, and transbronchial biopsies were performed every 2 weeks for 3 months postoperatively. No patient had a serious airway complication; 2 heart-lung recipients, not on prednisone preoperatively, had a minor tracheal slough detected on bronchoscopy that resolved spontaneously. Actuarial survival after heart-lung transplantation is 84% +/- 8% and 69% +/- 16% at 1 year and 2 years, respectively. We conclude that prednisone commencing at a dose of 0.5 mg/kg daily from the first postoperative day is a safe practice after heart-lung transplantation. The long-term use of low-dose prednisone before heart-lung transplantation does not preclude normal tracheal healing. The safety of prednisone before and immediately after single-lung transplantation awaits confirmation by further experience.

Reduction in bleeding after heart-lung transplantation. The importance of posterior mediastinal hemostasis.

To reduce perioperative hemorrhage following heart-lung transplantation, several technical modifications were introduced in June 1988 to secure better posterior mediastinal hemostasis. The intraoperative and postoperative use of blood and blood products, as well as the chest tube drainage in the first 24 hours postoperatively, were compared in the seven patients operated on since June 1988 with the nine patients operated on before that date. Significant (p less than 0.05) reductions were demonstrated in the intraoperative and postoperative transfusion of packed cells, in the postoperative administration of fresh frozen plasma, and in the chest tube drainage within the first 24 hours postoperatively. The one-month and total hospital mortality rates were 6 percent and 12.5 percent, respectively. It is concluded that newer techniques to obtain optimal posterior mediastinal hemostasis have significantly reduced blood loss following heart-lung transplantation in our experience and have contributed to our excellent early postoperative results.

Should heart-lung transplant donors and recipients be matched according to cytomegalovirus serologic status?

Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality after heart-lung transplantation. Primary CMV infections in previously seronegative recipients are more severe than reactivated or reinfections in seropositive patients, and this has led to a policy of obligatory donor-recipient CMV matching in several centers performing heart-lung transplantation. Of our 13 heart-lung transplants, three were done in CMV-seronegative patients who received CMV-positive grafts. The first patient did not seroconvert and exhibited no evidence of CMV infection despite close follow-up extending to almost 2 years. In the second patient, who required augmented immunosuppression because of recurrent lung rejection early postoperatively, fulminating CMV pneumonitis developed, which was ultimately controlled with ganciclovir and high-dose CMV immune globulin. As an outpatient, she is currently receiving ganciclovir maintenance therapy. The third patient, who received high-dose CMV immune globulin prophylaxis, had CMV isolated from her bronchoalveolar lavage fluid, as well as from urine, but remains clinically well 5 months after receiving her transplant. We conclude that the matching of donors and recipients for CMV serologic status is desirable, but not essential, before heart-lung transplantation. CMV immune globulin prophylaxis may be effective in preventing clinical CMV disease in patients receiving a CMV-mismatched graft, and severe CMV pneumonitis may be effectively treated by a combination of ganciclovir and high-dose CMV immune globulin therapy.

Importance of chronic aspiration in recipients of heart-lung transplants.

In a series of eleven recipients of heart-lung transplants (HLT), five have obliterative bronchiolitis. Five of the eleven patients have chronic cough as well as slower than normal gastric emptying and/or oesophageal dysmotility; all five have evidence of bronchiectasis and three have obliterative bronchiolitis. Three of the patients improved after the introduction of treatment to prevent reflux, and another, who had a large phytobezoar, improved after pyloroplasty. In patients with chronic cough after HLT, with or without dyspeptic symptoms or recurring pulmonary sepsis, investigation of oesophageal motility and gastric emptying should be undertaken.