Peter von Wichert

Vasorelaxant effect of glucagon-like peptide-(7-36) amide and amylin on the pulmonary circulation of the rat

The gastrointestinal peptides glucagon-like peptide-1(7-36)amide (GLP-1) and amylin are currently being tested in clinical trials for the treatment of diabetes mellitus due to their effects in lowering blood glucose. Receptors for these polypeptides also exist in the lung and since polypeptides are known to modulate airway and pulmonary vascular tone, we investigated whether GLP-1 and amylin act similarly in the lung. We compared their effects with the well-known actions of calcitonin gene-related peptide (CGRP) and vasoactive intestinal peptide (VIP). Both GLP-1 and amylin induced a dose-dependent and time-reversible endothelial-dependent relaxation of preconstricted pulmonary artery rings. Amylin was approximately as strong as VIP and CGRP, GLP-1 however, was 2.3-fold less potent. GLP-1 as well as amylin also reduced the vascular tone in the isolated, perfused and ventilated rat lung. In contrast to their action on the pulmonary vasculature, neither GLP-1 nor amylin showed any effect on the tone of isolated preconstricted trachea rings. In conclusion, GLP-1 and amylin represent two additional peptides which may modulate pulmonary vascular tone.

TNF-α, TNF-β, IL-6, and IL-10 Polymorphisms in Patients with Lung Cancer

Apart from cigarette smoking, genetic factors seem to be of importance in the development of lung cancer. The present case-control study investigated frequencies of five inflammatory response gene polymorphisms (TNF-α-308, TNF-β-Intron1-252, IL-6-174, IL-10-819 and IL-10-1082) in patients with lung cancer and controls. The study population consisted of 117 patients with lung cancer (77 patients with NSCLC, including 40 Squamous Cell Carcinoma and 26 Adenocarcinoma, and 40 patients with SCLC), 117 matched controls without pulmonary disease and 243 healthy individuals (population control). Genotype analyses revealed no difference in genotype frequencies using matched-pair analysis. However, in comparison to the population control, the IL-10-1082 genotypes carrying the G allele appeared with higher frequency in the SCLC group (p = 0.006) [SCLC: 84.6%, population controls: 64.6%]. This yields an odds ratio of 3.01 for SCLC (95% CI = [1.21, 7.48]). No associations were seen for all other polymorphisms analysed. The study raises the possibility of a correlation between the IL-10-1082_G allele and the presence of SCLC in a German population. The functional IL-10-1082 polymorphism correlates with altered IL-10 levels and might influence lung cancer susceptibility by altered inflammatory responses in the airways.

Proliferation and number of Clara cell 10-kDa protein (CC10)-reactive epithelial cells and basal cells in normal, hyperplastic and metaplastic bronchial mucosa

Abstract. Clara cell 10-kDa protein (CC10) is an inhibitor of phospholipase A2 and binds to phosphatidylinositol. It may therefore interfere with intracellular signal transduction. Bronchial CC10-reactive cells have been described by several authors. In contrast to the bronchiolar CC10-containing Clara cell, which is a progenitor cell of terminally differentiated airway epithelium, the role of bronchial CC10-reactive cells remains to be elucidated. We assessed the number of bronchial CC10-reactive cells in relation to cytokeratin (CK) expression and proliferative activity in normal, hyperplastic and squamous metaplastic epithelium. Sixty-five human bronchial mucosal specimens were investigated immunohistochemically for CK expression (CK7, CK13 and CK5/6), proliferative activity (MIB-1) and number of CC10-reactive epithelia. The proliferation fraction of CC10-reactive cells was assessed with double staining for MIB-1 and CC10. The proliferation index of the epithelium differed significantly between normal, hyperplastic and metaplastic epithelium. The number of CC10-reactive cells was inversely related to the epithelial proliferation. Bronchial CC10-reactive cells showed no proliferative activity as assessed using immunohistochemical double staining for CC10 and MIB-1. In contrast to normal and hyperplastic epithelium, squamous metaplasia disclosed CK5/6 in all epithelial layers, a loss of CK7 and a gain of CK13. We conclude that CC10-reactive cells have no progenitor role in the bronchial mucosa. However, because the proliferative activity is inversely related to the number of CC10-reactive cells, the CC10 protein may play a role in the regulation of epithelial repair. Squamous metaplasia most likely originates from basal cells.

Surfactant protein B intron 4 variation in German patients with COPD and acute respiratory failure.

Chronic obstructive pulmonary disease (COPD) is a major health problem. Genetic factors that contribute to the disease have been postulated. The pulmonary surfactant protein B (SP-B), which is essential for normal lung function, is considered as a candidate gene for COPD in this case-control study. We studied the SP-B intron 4 size variants in 346 individuals. This group consisted of 118 patients with chronic bronchitis or COPD, including 24 patients with acute respiratory failure (ARF) in COPD, 118 matched controls without pulmonary disease and 110 healthy individuals (population control). The frequency of intron 4 variants was similar in either control group (10.9%, 14.4% respectively), with a small increase in the COPD group (18.6%). This increase was due to a high increase of intron 4 variants in the ARF subgroup (37.5%, p = 0.003, OR 4.9, 95% CI: 1.76–13.6). The data indicate that SP-B intron 4 variants may associate with increased risk of ARF in COPD and may be used as a marker of susceptibility in this disease subgroup.

Effects of VIP and Related Peptides on Airway Mucus Secretion from Isolated Rat Trachea

Vasoactive intestinal polypeptide (VIP) is known as an important regulator of airway function. It has been suggested that VIP is involved in the pathogenesis of asthma due to its relaxant effects on smooth muscles. The present study was designed to characterize the effects of the peptides of the VIP family on airway mucus secretion. The peptides VIP, PHI, PACAP-27, PACAP-38, GLP-I, exendin-4, helodermin, helospectin I and helospectin II were investigated using isolated rat trachea. Data show that PACAP-27 is the most potent stimulator of airway mucus secretion (225% stimulation). The rank order of potency was PACAP-27 > VIP > helospectin II > PHI > exendin-4 = helodermin = helospectin I = PACAP-38. The addition of the protease inhibitor thiorphan enhanced the effects of PHI and helodermin, but not of the other peptides. These data show that the peptides of the VIP family stimulate airway mucus secretion differently.

Computer-Tomographically Guided Fiberbronchoscopic Transbronchial Biopsy of Small Pulmonary Lesions: A Feasibility Study

Small pulmonary lesions localized in peripheral airways or lung parenchyma are mostly not visible by means of flexible or rigid bronchoscopy for they are distal to the inspectable airway caliber. Therefore fluoroscopy is necessary to direct the flexible biopsy forceps or biopsy needle to the lesion. Even a two-dimensional fluoroscopic guidance does not guarantee an access to the focus. Therefore we investigated a method to overcome these problems. In 9 patients with peripheral lung lesions where the conventional method had failed to provide sufficient biopsies CT-guided bronchoscopy was done. Central airways were carefully inspected, and the flexible forceps was introduced into the bronchial branch leading to the focus under fluoroscopic control. Then the forceps was localized in the axial plane by CT and guided directly to the lesion. Subsequently the forceps was opened and contact to the lesion was confirmed by CT scan before the biopsies were taken. Thus the three-dimensional control of the position of the forceps made it possible to get biopsies directly from the region of interest. The method provides the possibility of reaching even small peripheral lesions that have been missed by the conventional techniques, thereby, although technically more difficult for the examiner, providing a smaller risk of complications and no additional discomfort for the patient.

Nitric oxide-dependent vasorelaxation and endothelial cell damage caused by mercury chloride

Mercury and its derivatives are known to constrict vascular smooth muscle cells. However, little is known about the role of endothelial cells in mercury-induced vasoreactivity. Using isolated, norepinephrine preconstricted rat aorta and pulmonary artery rings with intact endothelium, we demonstrate that mercury chloride (HgCl2) induces an endothelial-dependent vasorelaxation which was totally blocked by the nitric oxide inhibitor L-NAME. Besides this vasorelaxant effect, treatment with HgCl2 resulted in functional and morphological alterations of the endothelial cells. On aortic rings, endothelial cells were partly lifted from the basal membrane when incubated for 20 min in HgCl2 (10(-7) M)-containing buffer. At a concentration of 10(-6) M, the endothelial cells were completely denuded and acetylcholine vasorelaxation was abolished. Endothelial cell structure and function was preserved by incubating the vessels in HgCl2-containing rat blood instead of buffer. We conclude that HgCl2 induces an endothelial-dependent vasorelaxation and alters structure and function of vascular endothelial cells.

Periodic hemodynamics (flow motion) in peripheral arterial occlusive disease

PURPOSE The occurrence of periodic blood flow variations (flow motion) in health and disease is controversially discussed. This is partly due to not reporting the incidence and to performing the analysis solely visually. We have therefore studied flow motion with computerized methods. METHODS We used a computerized Prony spectral line estimator program to analyze the frequencies of resting skin blood flow variations, as determined by laser Doppler flowmetry on the thumb and great toe, in 50 male control subjects (group a), in 50 patients with mild peripheral arterial occlusive disease (PAOD stages I and II; group b), and in 25 patients with severe PAOD (stages III and IV; group c). RESULTS The median ankle/arm pressure ratio was 1.10 in the control group, 0.72 in the mild PAOD group, and 0.66 in the severe PAOD group. Slow wave flow motion was detected in 19% of all thumbs from groups a and b (systolic arm pressures > 100 mm Hg) and in 12% of the toes in the control group. Patients with mild PAOD exhibited slow wave flow motion in 46% of the toes. Patients with severe PAOD showed slow waves in 77% of the toes. The median flow motion frequencies were about 1.6 cycles/min for groups a and b, when present. The median frequency in group c was significantly higher at 4.0 cycles/min, though still in the range of slow waves. The median peak-to-through amplitude was between 17% and 20% of mean flow for all groups. CONCLUSIONS We conclude that evaluation of flow motion requires computerized frequency analysis and that slow wave flow motion is a perfusion pattern characteristic of PAOD rather than of normal perfusion states. This finding has potential implications for diagnostic and therapeutic approaches in arterial occlusive disease.

Effects of the nitric oxide/cGMP system compared with the cAMP system on airway mucus secretion in the rat

Mucus secretion of the airways is under the control of a variety of intracellular second messenger systems. Cyclic nucleotides such as cGMP, coupled to the recently discovered nitric oxide system, and cAMP are of outstanding interest in this respect. The present study used the modified Ussing chamber technique and mucins labelled with (35)SO(4) to investigate mucus secretion in the rat trachea to clarify the contribution of these different second messenger systems to the control of mucin secretion.A variety of drugs affecting either the generation or the breakdown of the respective cyclic nucleotides were used. Neither drugs interfering with nitric oxide synthase nor the phosphodiesterase isoenzyme responsible for cGMP breakdown nor cGMP analogues were able to affect mucus secretion. In contrast, stimulation of adenylate cyclase or inhibition of the respective phosphodiesterase resulted in a potent increase of mucus secretion. In conclusion, we failed to show the involvement of the nitric oxide/cGMP system, whereas the cAMP system seems to be a very efficient regulator of mucus secretion in the rat trachea.

Effects of selective and non-selective phosphodiesterase inhibitors on tracheal mucus secretion in the rat

The present study was designed to characterize the effects of unselective and isoenzyme-selective phosphodiesterase inhibitors on airway mucus secretion. The isolated rat trachea was incubated in a modified Ussing chamber. Mucus macromolecules were metabolically labelled with 35S. The inhibitors were applied at the luminal side. The unselective phosphodiesterase inhibitors theophylline, enprofylline and 3-isobutyl-methylxanthine stimulated mucus secretion in a concentration-dependent manner with half-maximum effects (EC50 values) at 690 microM, 400 microM and 46 microM, respectively. The adenosine antagonist 8-phenyltheophylline did not significantly stimulate mucus output, suggesting a negligible role of adenosine in the cellular mechanisms of mucus secretion. Adenosine itself did not increase radiolabel output. Rolipram, an inhibitor of phosphodiesterase isoenzyme IV, and zardaverine, which inhibits the isoenzymes III and IV, increased potently macromolecule output with EC50 values of 40 nM and 6 microM, respectively. The selective inhibitors of phosphodiesterase isoenzymes III and V, motapizone and zaprinast, did not influence airway mucus release, suggesting a relatively low activity of isoenzymes III and V in glands of rat trachea. The stimulatory effect of theophylline on airway mucus secretion may contribute to its beneficial action in chronic obstructive airway disease. Our data suggest that this effect is mediated predominantly by phosphodiesterase isoenzyme IV.