Pulmonary infections increase exhaled nitric oxide in lung transplant recipients: a longitudinal study

The aim of this longitudinal study was to test whether pulmonary infections influence fractional exhaled nitric oxide levels (FENO) in otherwise clinically-stable lung transplant recipients. Levels of FENO were measured at least on 11 occasions in nine lung transplant recipients who attended for routine or urgent clinical review over 27.0 +/- 3.2 months period. Diagnosis of infection was based on clinical symptoms, functional measurements and radiological findings. Concentrations of FENO were also determined in 12 healthy volunteers. During follow-up, six patients had one, two had three, and one had four episodes of pulmonary infections. Overall, six upper and 10 lower respiratory tract infections were noted. Recipients with active infections developed increased FENO levels as compared with their own baseline levels measured in the clinically well period (10.8 +/- 1.3 vs. 7.6 +/- 1.1 ppb, p < 0.05). After antibiotic treatment, elevated FENO concentrations returned to baseline in association with full clinical recovery. Baseline FENO levels in lung transplant recipients and in healthy volunteers (6.0 +/- 0.5 ppb) were similar. The sensitivity and specificity of FENO measurement in detecting pulmonary infections were 57 and 96%, respectively. Our data suggest that pulmonary infections are associated with increased FENO levels in patients with lung allografts. Nevertheless, the measurement of FENO by itself as a screening tool for infections seems to be limited by its low sensitivity.

Lung cancer in smoking patients inversely alters the activity of hOGG1 and hNTH1

N-Glycosylases excise the damaged adducts from DNA. 7,8-Dihydro-8-oxoguanine in human cells is repaired by OGG1 and hNTH1. The activities of hOGG1 and hNTH1 were measured, using modified and 32P labelled oligonucleotides, in bronchial biopsy samples of smoking patients with non-small cell lung carcinoma. The activity of hOOG1 was significantly higher in biopsies from tumour tissues compared with intra-individual control samples. On the contrary, the activity of endonuclease III homologue, hNTH1, was lower in tumours compared to controls. These opposing alterations in DNA repair enzymes may affect cancer growth due to the increased formation of AP sites.

Viscoelasticity of the vessel wall: the role of collagen and elastic fibers

The aortic wall contains collagen fibrils, smooth muscle cells, and elastic fibers as the primary load-bearing components. It is well known that the collagen fibrils bear loads in the circumferential direction, whereas elastic fibers provide longitudinal as well as circumferential support. Stiffening of the vessel wall is associated with loss of elastic tissue and increases in the collagen content: however, little is known about the mechanism of vessel wall stiffening with age. The purpose of this review is to attempt to relate structural changes that occur to the collagen and elastic fibers to changes in the viscoelastic behavior that are associated with aging. Analysis of the viscoelastic mechanical properties of collagen fibrils from tendon, skin, and aortic wall suggest that the collagen fibrils of aortic wall are different than those of other tissues. The elastic spring constant of the collacen fibrils in vessel walls is significantly less than that found in tendon, suggesting that the presence of type III collagen in aortic wall increases the flexibility of the collagen fibrils. Furthermore, it is hypothesized that changes in the interface between collagen fibrils, elastic fibers, and smooth muscle during aging and in connective tissue disorders leads to changes in the viscoelasticity of the vessel wall.

Molecular basis for elastic energy storage in mineralized tendon

Animals store elastic energy in leg and foot tendons during locomotion. In the turkey, much of the locomotive force generated by the gastrocnemius muscle is stored as elastic energy during tendon deformation. Little energy storage occurs within the muscle. During growth of some avians, including the turkey, leg tendons mineralize in the portions distal to the attached muscle and show increased tensile strength and modulus as a result. The purpose of this study is to test the hypothesis that the degree of elastic energy storage in mineralizing turkey tendon is directly related to the tendon mineral content. To test this hypothesis, the stress-strain behavior of tendons was separated into elastic and viscous components. Both the elastic spring constant and the elastic energy stored, calculated up to a strain of 20%, were found to be proportional to tendon mineral content. It is concluded that mineralization is an efficient means for increasing the amount of elastic energy storage that is required for increased load-bearing ability needed for locomotion of adult birds. Examination of molecular models of the hole region, where mineralization is initiated within the collagen fibril, leads to the hypothesis that elastic energy is stored in the tendon by direct stretching of the flexible regions. Flexible regions within the collagen molecule fall within the positively stained bands of the collagen D period. It is proposed that mineralization increases the stored elastic energy by preventing flexible regions within the positively stained bands from stretching. These observations suggest that mineralization begins in the hole region due to the large number of charged amino acid residues found in the d and e bands.

Quantification of pulmonary capillary endothelium-bound angiotensin converting enzyme inhibition in man

Angiotensin converting enzyme (ACE, kininase II) is an endothelial luminal ectoenzyme expressed abundantly on the pulmonary capillary endothelium and recognized as the site for the conversion of circulating angiotensin I to II. In the present study, we have applied recently developed methodologies for assaying pulmonary capillary endothelium-bound (PCEB) ACE activity in man, to estimate the interaction of an ACE inhibitor (enalaprilat) with PCEB ACE in human subjects. Trace amounts of the specific ACE substrate, 3H-benzoyl-Phe-Ala-Pro (3H-BPAP; 40 Ci or 2 nmol), was injected as a bolus into the subclavian vein and immediately blood was withdrawn from a radial arterial catheter. Plasma concentrations of surviving substrate and product (3H-benzoyl-Phe) were estimated and BPAP utilization was calculated during a single transpulmonary passage, at baseline (T(0)) and at 15 min (T(15)) and 2 h (T(120)) after intravenous administration of 1.5 g/kg enalaprilat in 12 normotensive subjects. This treatment had no significant effect on mean arterial pressure (91+/- 6 vs. 84 +/- 7 vs. 88 +/- 6 mm Hg for T(0), T(15) and T(120), respectively), but significantly decreased serum and PCEB ACE activities. When normalized to predrug (T(0)) activity levels, enalaprilat inhibited PCEB and serum ACE activities at T(15) 74 +/- 6% and 68 +/- 6%, respectively. However, 2 h after enalaprilat (T(120)), PCEB ACE inhibition was maintained at 66 +/- 7%, whereas serum ACE inhibition was reduced to 46 +/- 8% (P<.01 from PCEB ACE), suggesting a preferential PCEB ACE inhibitory effect of enalaprilat.

Changes in exhaled carbon monoxide and nitric oxide levels following allergen challenge in patients with asthma

Carbon monoxide is a product of haem degradation by haem oxygenase (HO), activated by inflammatory cytokines and oxidants. This study examined whether allergen challenge can increase exhaled CO levels, as a reflection of HO activation. Exhaled CO and nitric oxide, an expired gas also thought to reflect cytokine-induced airway inflammation, were measured in 15 atopic steroid-naive nonsmoking patients with asthma (13 males, aged 30+/-2 yrs) before and for up to 20 h after allergen challenge. Baseline CO (4.4+/-0.3 parts per million (ppm)) and NO (20.6+/-1.2 parts per billion (ppb)) levels were elevated in asthmatic as compared with nonsmoking normal volunteers (n = 37, 2.1+/-0.2 ppm and 7.0+/-0.1 ppb, respectively, p<0.05). In 10 patients with a dual response in the forced expiratory volume in one second (FEV1) there was a maximal increase in exhaled CO at 1 h (343+/-7.1%) and at 6 h (69+/-12%, p<0.01), followed by a maximal fall in FEV1 (28+/-9%, p<0.05) at 9 h, whereas the maximal NO increase was observed at 10 h (50.2+/-11.8%). The maximal increase in exhaled CO in single response patients (n = 5) was 30+/-2% during the early asthmatic reaction and 46.3+/-9.2% between 4 and 10 h, followed by a fall in FEV1 (9+/-3%, p>0.05) at 9 h, whereas exhaled NO was not significantly changed. In five patients exhaled CO was not attenuated by inhalation of increasing concentrations of histamine causing a 20% fall in FEV1 (PC20) or its subsequent relief by beta2-agonists. In conclusion, exhaled carbon monoxide is increased during the early and late asthmatic reactions independently of the change in airway calibre, while exhaled nitric oxide is increased only during the late reaction and follows the increase in carbon monoxide and fall in the forced expiratory volume in one second in time.

Increased levels of exhaled carbon monoxide in bronchiectasis: a new marker of oxidative stress

BACKGROUND

Bronchiectasis is a chronic inflammatory lung disease associated with increased production of oxidants due mostly to neutrophilic inflammation. Induction of heme oxygenase (HO-1) by reactive oxygen species is a general cytoprotective mechanism against oxidative stress. HO-1 catabolises heme to bilirubin, free iron and carbon monoxide (CO). Exhaled CO measurements may therefore reflect an oxidative stress and be clinically useful in the detection and management of inflammatory lung disorders.

METHODS

The levels of exhaled CO of 42 non-smoking patients with bronchiectasis treated or not treated with inhaled corticosteroids were compared with CO levels in 37 normal non-smoking subjects.

RESULTS

Levels of exhaled CO were raised in patients with bronchiectasis, both those treated with inhaled corticosteroids (n = 27, median 5.5 ppm, 95% CI 5.16 to 7.76) and those not treated with inhaled corticosteroids (n = 15, median 6.0 ppm. 95% CI 4.74 to 11.8), compared with normal subjects (n = 37, median 3.0 ppm, 95% CI 2.79 to 3.81, p = 0.0024). There was no correlation between exhaled CO and HbCO levels (r = 0.42, p = 0.12) in normal subjects (n = 7), nor between the urine cotinine concentration and exhaled CO levels (r = 0.2, p = 0.12).

CONCLUSIONS

Increased levels of exhaled CO may reflect induction of HO-1 and oxidative stress in bronchiectasis. Measurement of exhaled CO may be useful in the management of bronchiectasis and possibly other chronic inflammatory lung disorders.

Elevated levels of expired breath hydrogen peroxide in bronchiectasis

Airway inflammation is important in the development and progression of many lung diseases, including bronchiectasis. Activation of inflammatory cells such as neutrophils, eosinophils, and macrophages induces a respiratory burst resulting in the production of reactive oxygen species such as hydrogen peroxide (H2O2). We have measured exhaled H2O2 in patients with documented bronchiectasis and investigated whether the concentration of H2O2 is related to the disease severity, as defined by lung function. We also investigated whether the concentrations of expired H2O2 were different in bronchiectatic patients who received inhaled corticosteroids compared with steroid-naïve patients. In 37 patients with bronchiectasis (mean age, 45 +/- 2.5 yr; FEV1, 59 +/- 3% pred), mean H2O2 concentration in exhaled breath condensate was significantly elevated as compared with the values in 25 age-matched (mean age, 42 +/- 2 yr) normal subjects (0.87 +/- 0.01 versus 0.26 +/- 0.04 microM, p < 0.001). There was a significant negative correlation between H2O2 and FEV1 (r = -0.76, p < 0.0001). Patients treated with inhaled corticosteroids had values of H2O2 similar to those of steroid-naïve patients (0.8 +/- 0.1 versus 0.9 +/- 0.1, p > 0.05). We conclude that H2O2 is elevated in exhaled air condensate of patients with bronchiectasis and is correlated with disease severity. Measurement of H2O2 may be used as a simple noninvasive method to monitor airway inflammation and oxidative stress.

Effect of inhaled L-arginine on exhaled nitric oxide in normal and asthmatic subjects

BACKGROUND

Nitric oxide (NO) plays an important part in the regulation of many physiological functions and may also be involved in several pulmonary diseases. Endogenous NO is synthesised by different isoforms of NO synthase (NOS) from L-arginine.

METHODS

The effect of inhaled L-arginine 0.75 g (six normal and six asthmatic subjects), 1.5 g (six normal and six asthmatic subjects), and 3 g (seven normal and six asthmatic subjects) has been studied in a double blind placebo controlled, randomised, parallel group design study. In addition, the effect of a single dose (3 g) of inhaled L-alanine has been assessed in five normal and five asthmatic subjects.

RESULTS

L-arginine increased exhaled NO in a dose-dependent fashion with a maximum at 60 minutes. The cumulative effect of L-arginine (3 g) on NO in asthmatic subjects, expressed as the area under the curve in arbitrary units (au) and compared with the effect of placebo (0.9% NaCl), was significantly higher (mean 0.11 au; 95% confidence interval (CI) 0.03 to 0.19) than in normal subjects (0.012 au; 95% CI 0.002 to 0.022). There was a negative correlation (r = -0.72) between the increase in exhaled NO and the fall in forced expiratory volume in one second (FEV1) (0.034 au, 95% CI 0.030 to 0.038) after 3 g L-arginine in asthmatic subjects. Inhalation of 3 g of L-alanine produced a similar reduction in FEV1 (0.033 au, 95% CI 0.007 to 0.059) but no significantly different changes in exhaled NO (0.017 au, 95% CI 0.001 to 0.039) compared with placebo (0.020 au, 95% CI 0.001 to 0.042).

CONCLUSIONS

An increase in the amount of substrate for NOS increases the formation of endogenous NO. L-arginine may have therapeutic potential in diseases in which there is defective production of NO, but in asthma it may amplify the inflammatory response in the airways.

Membrane lipid perturbation modifies the set point of the temperature of heat shock response in yeast

Addition of a saturated fatty acid (SFA) induced a strong increase in heat shock (HS) mRNA transcription when cells were heat-shocked at 37 degrees C, whereas treatment with an unsaturated fatty acid (UFA) reduced or eliminated the level of HS gene transcription at 37 degrees C. Transcription of the delta 9-desaturase gene (Ole1) of Histoplasma capsulatum, whose gene product is responsible for the synthesis of UFA, is up-regulated in a temperature-sensitive strain. We show that when the L8-14C mutant of Saccharomyces cerevisiae, which has a disrupted Ole1 gene, is complemented with its own Ole1 coding region under control of its own promoter or Ole1 promoters of H. capsulatum, the level of HS gene transcription depends on the activity of the promoters. Fluorescence anisotropy of mitochondrial membranes of completed strains corresponded to the different activity of the Ole1 promoter used. We propose that the SFA/UFA ratio and perturbation of membrane lipoprotein complexes are involved in the perception of rapid temperature changes and under HS conditions disturbance of the preexisting membrane physical state causes transduction of a signal that induces transcription of HS genes.

Role of nitric oxide in regulating cerebrocortical oxygen consumption and blood flow during hypercapnia

The effect of the nitric oxide (NO) synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) on the response of cerebrocortical oxygen consumption (CMRO2) and blood flow (CBF) to two levels of hypercapnia (PaCO2 approximately 60 mm Hg and PaCO2 approximately 90 mm Hg) was investigated in ketamine-anesthetized rats. CBF was calculated using the Kety-Schmidt approach and CMRO2 was calculated from the product of CBF and the arteriovenous (superior sagittal sinus) difference for oxygen. L-NAME treatment did not have a significant effect on either CMRO2 or CBF under normocapnic conditions but inhibited the hypercapnic increase of CMRO2 and the hypercapnic increase in CBF. These results suggest that NO plays a role in the response of CMRO2 and CBF during hypercapnia and are consistent with the suggestion that at least part of the increase in CBF observed during hypercapnia is coupled to an increase in CMRO2.

The temperature-dependent expression of the desaturase gene desA in Synechocystis PCC6803

We examined the temperature-dependent regulation of the expression of the desA gene, which encodes delta 12 desaturase of Synechocystis PCC6803. The level of desA transcript increased 10-fold within 1 h upon a decrease in temperature from 36 degrees C to 22 degrees C. This suggests that the low-temperature-induced desaturation of membrane lipid fatty acids is regulated at the level of the expression of the desaturase genes. The accumulation of the desA transcript depended on the extent of temperature change over a certain threshold level, but not on the absolute temperature.