Accuracy of surgical complication rate estimation using ICD-10 codes.

BACKGROUND: The ICD-10 codes are used globally for comparison of diagnoses and complications, and are an important tool for the development of patient safety, healthcare policies and the health economy. The aim of this study was to investigate the accuracy of verified complication rates in surgical admissions identified by ICD-10 codes and to validate these estimates against complications identified using the established Global Trigger Tool (GTT) methodology. METHODS: This was a prospective observational study of a sample of surgical admissions in two Norwegian hospitals. Complications were identified and classified by two expert GTT teams who reviewed patients' medical records. Three trained reviewers verified ICD-10 codes indicating a complication present on admission or emerging in hospital. RESULTS: A total of 700 admissions were drawn randomly from 12 966 procedures. Some 519 possible complications were identified in 332 of 700 admissions (47·4 per cent) from ICD-10 codes. Verification of the ICD-10 codes against information from patients' medical records confirmed 298 as in-hospital complications in 141 of 700 admissions (20·1 per cent). Using GTT methodology, 331 complications were found in 212 of 700 admissions (30·3 per cent). Agreement between the two methods reached 83·3 per cent after verification of ICD-10 codes. The odds ratio for identifying complications using the GTT increased from 5·85 (95 per cent c.i. 4·06 to 8·44) to 25·38 (15·41 to 41·79) when ICD-10 complication codes were verified against patients' medical records. CONCLUSION: Verified ICD-10 codes strengthen the accuracy of complication rates. Use of non-verified complication codes from administrative systems significantly overestimates in-hospital surgical complication rates.

Assessing neuropathic pain in patients with low back-related leg pain: Comparing the painDETECT Questionnaire with the 2016 NeuPSIG grading system.

BACKGROUND: Low back-related leg pain with nerve root involvement is conceptually regarded as a neuropathic condition. However, it is uncertain to what extent patients with this condition can be formally classified with neuropathic pain. METHOD: First, we used the 2016 revision of the IASP Special Interest Group on Neuropathic Pain (NeuPSIG) grading system for neuropathic pain to grade patients suffering from low back-related leg pain and a corresponding disc herniation with either unlikely, possible, probable or definite neuropathic pain. Examination included bedside quantitative sensory testing. Next, we used the clinical classification based on the 2016 NeuPSIG grading system as a reference standard to assess the ability of the painDETECT Questionnaire to identify patients with neuropathic pain. RESULTS: Of the 50 included patients, six (12%) fulfilled the clinical classification criteria for probable and 44 (88%) for definite neuropathic pain, while none were graded unlikely or possible. According to painDETECT, 23 patients (46%) were classified with unlikely neuropathic pain, 18 patients (36%) had an uncertain condition and in nine patients (18%) neuropathic pain was likely. Among the 44 patients graded as having definite neuropathic pain by the clinical classification, eight were classified as likely neuropathic pain by painDETECT, resulting in an agreement of 18%. Of these 44 patients graded with definite neuropathic pain, painDETECT classified 21 patients (48%) as unlikely and 15 (34%) as uncertain. CONCLUSION: Our results do not support the use of painDETECT as a screening tool to classify or grade neuropathic components in patients with low back-related leg pain. SIGNIFICANCE: The painDETECT Questionnaire performed poorly at detecting neuropathic pain among patients with low back-related leg pain, compared to clinical examination based on the 2016 NeuPSIG grading system as a reference standard. Our results do not support the use of painDETECT as a screening tool to classify or grade neuropathic components in this population.

Pain-related fear and functional recovery in sciatica: results from a 2-year observational study.

OBJECTIVES: The purpose of this study was to explore the associations between pain-related fear, pain disability, and self-perceived recovery among patients with sciatica and disk herniation followed up for 2 years. PATIENTS AND METHODS: Pain-related fear was measured by the Tampa Scale for Kinesiophobia (TSK) and the Fear-Avoidance Beliefs Questionnaire-Physical Activity (FABQ-PA) subscale. Disability was measured by the Maine-Seattle Back Questionnaire. At 2 years, patients reported their sciatica/back problem on a global change scale ranging from completely gone to much worse. No specific interventions regarding pain-related fear were provided. RESULTS: Complete data were obtained for 372 patients. During follow-up, most patients improved. In those who at 2 years were fully recovered (n=66), pain-related fear decreased substantially. In those who did not improve (n=50), pain-related fear remained high. Baseline levels of pain-related fear did not differ significantly between those who were fully recovered and the rest of the cohort. In the total cohort, the correlation coefficients between the 0-2-year change in disability and the changes in the TSK and the FABQ-PA were 0.33 and 0.38, respectively. In the adjusted regression models, the 0-2-year change in pain-related disability explained 15% of the variance in the change in both questionnaires. CONCLUSION: Pain-related fear decreased substantially in patients who recovered from sciatica and remained high in those who did not improve. Generally, the TSK and the FABQ-PA yielded similar results. To our knowledge, this is the first study that has assessed pain-related fear in patients who recover from sciatica.

A rare missense mutation in CHRNA4 associates with smoking behavior and its consequences.

Using Icelandic whole-genome sequence data and an imputation approach we searched for rare sequence variants in CHRNA4 and tested them for association with nicotine dependence. We show that carriers of a rare missense variant (allele frequency=0.24%) within CHRNA4, encoding an R336C substitution, have greater risk of nicotine addiction than non-carriers as assessed by the Fagerstrom Test for Nicotine Dependence (P=1.2 × 10(-4)). The variant also confers risk of several serious smoking-related diseases previously shown to be associated with the D398N substitution in CHRNA5. We observed odds ratios (ORs) of 1.7-2.3 for lung cancer (LC; P=4.0 × 10(-4)), chronic obstructive pulmonary disease (COPD; P=9.3 × 10(-4)), peripheral artery disease (PAD; P=0.090) and abdominal aortic aneurysms (AAAs; P=0.12), and the variant associates strongly with the early-onset forms of LC (OR=4.49, P=2.2 × 10(-4)), COPD (OR=3.22, P=2.9 × 10(-4)), PAD (OR=3.47, P=9.2 × 10(-3)) and AAA (OR=6.44, P=6.3 × 10(-3)). Joint analysis of the four smoking-related diseases reveals significant association (P=6.8 × 10(-5)), particularly for early-onset cases (P=2.1 × 10(-7)). Our results are in agreement with functional studies showing that the human α4ß2 isoform of the channel containing R336C has less sensitivity for its agonists than the wild-type form following nicotine incubation.

Evolution of DOHaD: the impact of environmental health sciences.

Environmental exposures have a significant influence on the chronic health conditions plaguing children and adults. Although the Developmental Origins of Health and Disease (DOHaD) paradigm historically has focused on nutrition, an expanding body of research specifically communicates the effects of chemical exposures on early-life development and the propagation of non-communicable disease across the lifespan. This paper provides an overview of 20 years of research efforts aimed at identifying critical windows of susceptibility to environmental exposures and the signaling changes and epigenetic influences associated with disease progression. DOHaD grants funded by the National Institute of Environmental Health Sciences (NIEHS) in 1991, 2001 and 2011 are identified by grant-analysis software, and each portfolio is analyzed for exposures, disease endpoints, windows of exposure, study design and impact on the field based on publication data. Results show that the 1991 and 2001 portfolios comprised metals, PCBs and air pollutants; however, by 2011, the portfolio has evolved to include or expand the variety of endocrine disruptors, pesticides/persistent organic pollutants and metals. An assortment of brain-health endpoints is most targeted across the portfolios, whereas reproduction and cancer increase steadily over the same time period, and new endpoints like obesity are introduced by 2011. With mounting evidence connecting early-life exposures to later-life disease, we conclude that it is critical to expand the original DOHaD concept to include environmental chemical exposures, and to continue a research agenda that emphasizes defining sensitive windows of exposure and the mechanisms that cause disease.

The prognosis of self-reported paresthesia and weakness in disc-related sciatica.

PURPOSE: To explore how patients with sciatica rate the 'bothersomeness' of paresthesia (tingling and numbness) and weakness as compared with leg pain during 2 years of follow-up. METHODS: Observational cohort study including 380 patients with sciatica and lumbar disc herniation referred to secondary care. Using the Sciatica Bothersomeness Index paresthesia, weakness and leg pain were rated on a scale from 0 to 6. A symptom score of 4-6 was defined as bothersome. RESULTS: Along with leg pain, the bothersomeness of paresthesia and weakness both improved during follow-up. Those who received surgery (n = 121) reported larger improvements in both symptoms than did those who were treated without surgery. At 2 years, 18.2% of the patients reported bothersome paresthesia, 16.6% reported bothersome leg pain, and 11.5% reported bothersome weakness. Among patients with no or little leg pain, 6.7% reported bothersome paresthesia and 5.1% bothersome weakness. CONCLUSION: During 2 years of follow-up, patients considered paresthesia more bothersome than weakness. At 2 years, the percentage of patients who reported bothersome paresthesia was similar to the percentage who reported bothersome leg pain. Based on patients' self-report, paresthesia and weakness are relevant aspects of disc-related sciatica.

Overweight in polycystic ovary syndrome. An update on evidence based advice on diet, exercise and metformin use for weight loss.

AIM: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in premenopausal women affecting 5-10%. Nearly 50% are overweight or obese, which result in a more severe phenotype of PCOS. Weight loss is therefore considered the first line treatment in overweight women with PCOS. The aim of this study was to appoint evidence based and clinically applicable advises on weight loss in overweight women with PCOS. METHODS: A review of the existing literature on weight loss through lifestyle modification and/or metformin treatment in overweight women with PCOS. The primary outcome was weight loss. The clinical manifestations of hyperandrogenism and menstrual cyclicity were secondary outcomes. Metabolic parameters were not included in the present review. RESULTS: Weight loss is most effectively achieved through a 12-1500 kcal/day diet, which results in a clinically relevant weight loss. The type of diet has no implications for degree of weight loss. Physical activity has no significant additive effect on weight loss. Metformin combined with a low calorie diet has subtle additive effect on weight loss and level of androgens when compared to diet alone. CONCLUSION: Weight loss through life style changes, preferably a low calorie diet, should be the first line treatment in overweight/obese women with PCOS. Metformin can be considered as an additional treatment but has subtle additive effect.

Impact of the World Health Organization's Surgical Safety Checklist on safety culture in the operating theatre: a controlled intervention study.

BACKGROUND: Positive changes in safety culture have been hypothesized to be one of the mechanisms behind the reduction in mortality and morbidity after the introduction of the World Health Organization's Surgical Safety Checklist (SSC). We aimed to study the checklist effects on safety culture perceptions in operating theatre personnel using a prospective controlled intervention design at a single Norwegian university hospital. METHODS: We conducted a study with pre- and post-intervention surveys using the intervention and control groups. The primary outcome was the effects of the Norwegian version of the SSC on safety culture perceptions. Safety culture was measured using the validated Norwegian version of the Hospital Survey on Patient Safety Culture. Descriptive characteristics of operating theatre personnel and checklist compliance data were also recorded. A mixed linear regression model was used to assess changes in safety culture. RESULTS: The response rate was 61% (349/575) at baseline and 51% (292/569) post-intervention. Checklist compliance ranged from 77% to 85%. We found significant positive changes in the checklist intervention group for the culture factors 'frequency of events reported' and 'adequate staffing' with regression coefficients at -0.25 [95% confidence interval (CI), -0.47 to -0.07] and 0.21 (95% CI, 0.07-0.35), respectively. Overall, the intervention group reported significantly more positive culture scores-including at baseline. CONCLUSIONS: Implementation of the SSC had rather limited impact on the safety culture within this hospital.

Molecular characterization of a cancer-related single nucleotide polymorphism in the pro-inflammatory interleukin-1B gene.

Interleukin-1ß is a key pro-inflammatory cytokine that has been associated with chronic inflammation and inflammation-related cancer initiation and progression. There are inter-individual differences in IL1B expression which may be due to single nucleotide polymorphisms (SNPs) in the regulatory regions of the gene. We have previously shown that a SNP located in the promoter of the IL1B gene (the IL1B T-31C SNP) was associated with lung cancer risk. Interestingly, the presence of the C allele was also associated with reduced IL1B expression in normal lung tissue of lung cancer patients. In the present study, we found that differential binding patterns of nuclear proteins to oligonucleotide probes containing the IL1B -31C allele compared to those with the T allele were due to specific binding of the transcription factor Yin Yang 1 (YY1). We further found evidence that specific recruitment of YY1 to the -31C region of the IL1B promoter regulated IL1B gene expression using siRNA directed towards YY1. The results indicate that the presence of a C allele at the -31 position may lead to decreased expression of the IL1B gene due to a specific binding of YY1 in lung epithelial cells. Our study provides functional significance of allelic variation at a single locus in the IL1B promoter and contributes to understanding the regulation of IL1B in inflammation-related carcinogenesis.

Estimation of the prevalence of primary Sjögren's syndrome in two age-different community-based populations using two sets of classification criteria: the Hordaland Health Study.

OBJECTIVE: To estimate the point prevalence of primary Sjögren's syndrome (pSS) in two populations, aged 40-44 and 71-74 years, using two sets of classification criteria. METHODS: The participating individuals were recruited from the Hordaland Health Study (HUSK) conducted during 1997-99. A total of 18 592 individuals born 1953-57 and 3346 individuals born 1925-27 were sent a questionnaire covering various health-related questions, including four questions about sicca symptoms. Among those answering positive to at least one of the four questions, 99 and 90 individuals born 1953-57 and 1925-27, respectively, were examined further. For diagnosis of pSS two classifications were used, the preliminary European criteria from 1993, and the revised European criteria from 1996. RESULTS: By using the two classification criteria from 1993 and 1996, the point prevalences were 0.44% [95% confidence interval (CI) 0.34-0.57] and 0.22% (95% CI 0.15-0.32), respectively, for the population group born 1953-57. The corresponding estimates were 3.39% (95% CI 2.77-4.14) and 1.40% (95% CI 1.02-1.92) for the population born 1925-27. CONCLUSION: The point prevalence of pSS was approximately seven times higher in the elderly population aged 71-74 years compared to individuals aged 40-44 years, regardless of the classification criteria used.

Analysis of resveratrol as a lung cancer chemopreventive agent in A/J mice exposed to benzo[a]pyrene.

Resveratrol inhibits PAH bioactivation through reduced expression of the CYP1A1 and CYP1B1 genes in human bronchial epithelial cells. Ad libitum access to a diet containing resveratrol showed no effect on benzo[a]pyrene-induced lung tumorigenesis in A/J mice. Also, resveratrol did not change CYP1A1 and CYP1B1 gene expression or benzo[a]pyrene protein adduct levels in the lung tissue. The lack of chemopreventive activity may have been caused by insufficient concentrations or nonreactive forms of resveratrol in the lungs.

Resveratrol inhibits benzo[a]pyrene-DNA adduct formation in human bronchial epithelial cells.

Resveratrol (trans-3,4',5-trihydroxystilbene), a phytoalexin present in various plants and foods, has in several in vitro and in vivo studies demonstrated cancer chemopreventive and chemotherapeutic potential. We investigated the in vitro effect of resveratrol on benzo[a]pyrene (B[a]P) -induced DNA adducts in human bronchial epithelial cells. This was compared to the effect of resveratrol on the expression of the cytochrome P450 (CYP) genes CYP1A1 and CYP1B1 and the formation of B[a]P metabolites. Exposure of BEAS-2B and BEP2D cells to B[a]P and increasing concentrations of resveratrol resulted in a dose- and time-dependent inhibition of DNA adduct formation quantified by (32)P-postlabelling. Supporting this result, resveratrol was shown to inhibit CYP1A1 and CYP1B1 gene expression, as measured by real-time reverse transcriptase-polymerase chain reaction. Also, a significant correlation was found between the number of DNA adducts and the mRNA levels of these genes. Using HPLC analysis, a concomitant decrease in the formation of B[a]P-derived metabolic products was detected. In conclusion, these data lend support to a chemopreventive role of resveratrol in polycyclic aromatic hydrocarbon-induced carcinogenesis.

Polymorphisms in CYP1A1, GSTM1, GSTT1 and lung cancer below the age of 45 years.

BACKGROUND: A genetic component of early-onset lung cancer has been suggested. The role of metabolic gene polymorphisms has never been studied in young lung cancer cases. Phase 1 and Phase 2 gene polymorphisms are involved in tobacco carcinogens' metabolism and therefore in lung cancer risk. METHODS: The effect of metabolic gene polymorphisms on lung cancer at young ages was studied by pooling data from the Genetic Susceptibility to Environmental Carcinogens (GSEC) database. All primary lung cancer cases of both sexes who were Caucasian and

Chemiluminescence response of granulocytes from elite athletes during recovery from one or two intense bouts of exercise.

In this study nine elite athletes each participated in three different 24- h trials, as follows: (1) complete bed rest (REST), (2) one bout of exercise at 1515 hours (ONE-EX), (3) two exercise bouts, one at 1100 hours and one at 1515 hours (TWO-EX-3 h), and (4) two exercise bouts, one at 0800 hours and one at 1515 hours (TWO-EX-6 h). Exercise was performed on a cycle ergometer with 10 min of warm-up and then 65 min at an exercise intensity of 75% of maximum oxygen uptake (VO(2max)). The polymorphonuclear neutrophil (PMN) counts increased consistently in response to exercise, and more in trial TWO-EX-3 h than in the two other exercise trials (P < 0.01). The respiratory burst of PMN was measured as chemiluminescence (CL), obtained with phorbol myristate (PMA) and serum-opsonised zymosan (SOZ) as stimulators. Exercise triggered the CL response for a defined number of PMN, significantly above baseline (REST) values (P < 0.05) for ONE-EX and TWO-EX-3 h, but not for TWO-EX-6 h. The strongest response was observed for TWO-EX-3 h, but the difference between exercise procedures was not significant. However, as a novel approach, a comparison was made using total oxidative potentials per litre of blood, as obtained by combining CL values and PMN numbers. TWO-EX-3 h yielded significantly higher values than the other experimental treatments. Thus, by this measure the total oxidative potential of PMN x l(-1) blood remains at a higher level with short intervals between exercise bouts (i.e. 3 h instead of 6 h), possibly due to a combined effect of cell number increase and the priming state of PMN. This may suggest that for intensive training twice a day, a recovery phase of 5-6 h is preferable. The elevation in cell number is best explained by a combined effect of catecholamines and cortisol. Growth hormone is one probable candidate as a stimulator of CL, but other molecular participants that respond to exercise may exert roles as either stimulators or inhibitors of CL.

Metabolic gene polymorphism frequencies in control populations.

Using the International Project on Genetic Susceptibility to Environmental Carcinogens (GSEC) database containing information on over 15,000 control (noncancer) subjects, the allele and genotype frequencies for many of the more commonly studied metabolic genes (CYP1A1, CYP2E1, CYP2D6, GSTM1, GSTT1, NAT2, GSTP, and EPHX) in the human population were determined. Major and significant differences in these frequencies were observed between Caucasians (n = 12,525), Asians (n = 2,136), and Africans and African Americans (n = 996), and some, but much less, heterogeneity was observed within Caucasian populations from different countries. No differences in allele frequencies were seen by age, sex, or type of controls (hospital patients versus population controls). No examples of linkage disequilibrium between the different loci were detected based on comparison of observed and expected frequencies for combinations of specific alleles.

Biomarkers of genotoxicity of urban air pollution. Overview and descriptive data from a molecular epidemiology study on populations exposed to moderate-to-low levels of polycyclic aromatic hydrocarbons: the AULIS project.

Epidemiologic studies indicate that prolonged exposure to high pollution levels is associated with increased risk of cancer, especially lung cancer. However, under conditions of moderate or low air pollution, epidemiologic evidence does not permit reliable conclusions. Biomarker-based population studies may serve as complementary tools providing a better understanding of the relative contribution of ambient atmospheric pollution to the overall genotoxic burden suffered by city dwellers. However, past efforts to apply biomarkers to studies of low levels exposure to urban air pollution have given inconclusive results, partly because of the absence of adequate data on personal exposure, covering a time-window which is appropriate for the biomarkers being examined, as well as a battery of biomarkers reflecting different stages of the carcinogenic process. In the present paper, the potential of biomarker-based population studies to aid the assessment of the genotoxic and carcinogenic effects of urban air pollution is reviewed by reference to the achievements and limitations of earlier reported studies. The design and methodology adopted in a recently completed large-scale population study, carried out in the context of the European Union Environment and Climate Programme, known by the short name of AULIS project, is discussed and descriptive statistics of the main findings of the project are presented. These findings indicate that for cohorts suffering moderate-to-low exposures to airborne particulate-bound polycyclic aromatic hydrocarbons (PAHs), no simple correlation with biomarkers of genotoxicity existed and suggest that additional factors made a significant contribution to the overall genotoxic burden.

Mutability of p53 hotspot codons to benzo(a)pyrene diol epoxide (BPDE) and the frequency of p53 mutations in nontumorous human lung.

p53 mutations are common in lung cancer. In smoking-associated lung cancer,the occurrence of G:C to T:A transversions at hotspot codons, e.g., 157, 248, 249,and 273, has been linked to the presence of carcinogenic chemicalsin tobacco smoke including polycyclic aromatic hydrocarbons suchas benzo(a)pyrene (BP). In the present study, we have used a highly sensitive mutation assay to determine the p53 mutation load in nontumorous human lung and to study the mutability of p53 codons 157, 248, 249, and 250 to benzo(a)pyrene-diol-epoxide (BPDE), an active metabolite of BP in human bronchial epithelial BEAS-2B cells. We determined the p53 mutational load at codons 157, 248, 249, and 250 in nontumorous peripheral lung tissue either from lung cancer cases among smokers or noncancer controls among smokers and nonsmokers. A 5-25-fold higher frequency of GTC(val) to TTC(phe) transversions at codon 157 was found in nontumorous samples (57%) from cancer cases (n = 14) when compared with noncancer controls (n = 8; P < 0.01). Fifty percent (7/14) of the nontumorous samples from lung cancer cases showed a high frequency of codon 249 AGG(arg) to AGT(ser) mutations (P < 0.02). Four of these seven samples with AGT(ser) mutations also showed a high frequency of codon 249 AGG(arg) to ATG(met) mutations, whereas only one sample showed a codon 250 CCC to ACC transversion. Tumor tissue from these lung cancer cases (38%) contained p53 mutations but were different from the above mutations found in the nontumorous pair. Noncancer control samples from smokers or nonsmokers did not contain any detectable mutations at codons 248, 249, or 250. BEAS-2B bronchial epithelial cells exposed to doses of 0.125, 0.5, and 1.0 microM BPDE, showed G:C to T:A transversions at codon 157 at a frequency of 3.5 x 10(-7), 4.4 x 10(-7), and 8.9 x 10(-7), respectively. No mutations at codon 157 were found in the DMSO-treated controls. These doses of BPDE induced higher frequencies, ranging from 4-12-fold, of G:C to T:A transversions at codon 248, G:C to T:A transversions and G:C to A:T transitions at codon 249, and C:G to T:A transitions at codon 250 when compared with the DMSO-treated controls. These data are consistent with the hypothesis that chemical carcinogens such as BP in cigarette smoke cause G:C to T:A transversions at p53 codons 157, 248, and 249 and that nontumorous lung tissues from smokers with lung cancer carry a high p53 mutational load at these codons.

Lung carcinogenesis: resveratrol modulates the expression of genes involved in the metabolism of PAH in human bronchial epithelial cells.

Studies suggest that resveratrol (trans-3,4',5-trihydroxystilbene), which is a diphenolic antioxidant found in plants and foods, has cancer chemopreventive and chemotherapeutic potential. A lower risk of lung cancer among consumers of wine compared with consumers of other beverages has been observed, which may be partly attributed to the high content of resveratrol particularly in red wine. We have studied the effect of resveratrol on the expression of genes involved in the metabolism of polycyclic aromatic hydrocarbons in the human bronchial epithelial cell line BEP2D. Expression of the cytochrome P450 1A1 (CYP1A1) and 1B1 (CYP1B1), microsomal epoxide hydrolase (mEH), and glutathione S-transferase P1 (GSTP1) genes was measured by quantitative reverse transcriptase-polymerase chain reaction. The cells were treated either with benzo[a]pyrene or 2,3,7,8-tetrachlorodibenzo-p-dioxin in the presence or absence of resveratrol. Resveratrol inhibited both the constitutive and the induced expression of CYP1A1 and CYP1B1 in a dose-dependent manner. In contrast, the expression of the mEH gene was increased in response to resveratrol and no change in the expression of GSTP1 was found. The altered gene expression in response to resveratrol was reflected in a reduced overall level of benzo[a]pyrene metabolism. These data indicate that resveratrol may exert lung cancer chemopreventive activity through altering the expression of genes involved in the metabolism of polycyclic aromatic hydrocarbons, resulting in altered formation of carcinogenic benzo[a]pyrene metabolites in human bronchial epithelial cells.