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Biomedical subjects

U Mercke

Publications and source records attributed to U Mercke.

At least 37 records · Page 2Linked to original sources
PubMed1986

Capsaicin stimulates mucociliary activity by releasing substance P and acetylcholine.

Intraarterial injection of the neuropeptide substance P (SP) accelerates mucociliary (MC) activity. The physiological significance of this finding was investigated using capsaicin, which is known to release SP from unmyelinated C-fibers in sensory nerves. Capsaicin (3.0-150.0 micrograms/kg) stimulated MC activity in the rabbit maxillary sinus in vivo, recorded with a photoelectric technique. This effect was resistant to pretreatment with the adrenergic blocker guanethidine, and to a combination of propranolol and phentolamine. Pretreatment with an SP antagonist (D-Pro2, D-Trp7,9)SP totally inhibited the effect of capsaicin. The muscarinic antagonist atropine suppressed the initial phase of the response to capsaicin, whereas the response was uniformly suppressed by the ganglionic blocker hexamethonium. These results suggest that capsaicin activates a reflex, via afferent C-fibers containing SP and efferent parasympathetic cholinergic neurons. The final response of the MC system reflects the local release of both SP and acetylcholine.

Acetylcholine↗
PubMed1986

Anatomic findings one year after combined approach tympanoplasty.

Fifty-six patients were treated surgically for middle ear cholesteatoma using the combined approach tympanoplasty technique. One year later a second-look procedure was performed in all the patients, which permitted the anatomic effects of the combined technique to be mapped out before ossicular reconstruction was performed. At three, six, and twelve months after the first operation the development of retraction pockets was also studied. Recurrent cholesteatoma was found in twelve cases (21.4%), and residual cholesteatoma in fourteen (25%). The posterior tympanotomy was closed in 31 cases (55.4%), whereas the mastoidectomy cavity was overgrown and closed in 22 (39.4%). Twelve months after the first operation (just before the second look), a retraction pocket was found in twenty-one cases (37.5%), and at the second-look operation twelve of these were proven to be a manifest recurrent cholesteatoma. The formation of new retraction pockets was found to be time-dependent, that is, to increase almost linearly during the control interval between the operations. The investigation shows the necessity for standardizing the presentation of results after cholesteatoma operations and the importance of determining a convenient postoperative time for reporting the incidence of cholesteatoma recurrences.

Cholesteatoma↗
PubMed1985

Substance P antagonists and mucociliary activity in rabbit.

Substance P (SP) is known to accelerate mucociliary (m.c.) activity in the rabbit maxillary sinus in vivo. The physiological significance of this finding was investigated by testing three putative SP antagonists. [Arg5, D-Trp7,9, Nle11]SP5-11 could not be used as an antagonist because it stimulated m.c. activity. [D-Arg1, D-Trp7,9, Leu11]SP had no effect on the m.c. activity changes induced by SP. [D-Pro2, D-Trp7,9]SP was found to be an effective antagonist, 1 mg/kg of this drug reversibly inhibiting both the effects of 0.1 micrograms/kg SP and the stimulating effect of 1.0 micrograms/kg bradykinin and 30.0 micrograms/kg capsaicin; the stimulating effect of 0.5 micrograms/kg methacholine was not inhibited. It is suggested that bradykinin and capsaicin stimulate m.c. activity at least partly by releasing SP. The results of this investigation also support the view that the accelerating effect of SP on m.c. activity reflects physiological SP-mediated protective mechanisms in the airways. It is concluded that [D-Pro2,D-Trp7,9]SP is a useful pharmacological tool for studying the role of SP in the control of m.c. activity in rabbits.

Animals↗
PubMed1985

Effects of nicotine bitartrate on mucociliary activity.

The in vivo effect of nicotine bitartrate on mucociliary (mc) activity in the rabbit maxillary sinus was investigated. An animal model was used, which permitted administration of drugs directly into the artery feeding the sinus and simultaneous recording of changes in the mc activity. When nicotine was given ia (0.5-10.0 micrograms/kg) it resulted in a brief (1 min at most) acceleration of the mc wave frequency. The response was dose-dependent and a maximum increase of 34.9% was recorded at a dose of 10.0 micrograms/kg. The response was inhibited by a preceding injection of the ganglionic blocker hexamethonium (0.2 mg/kg) or the cholinergic antagonist atropine (0.2 mg/kg). The alpha and beta-adrenoceptor antagonists phentolamine (0.2 mg/kg) and propranolol (0.2 mg/kg) did not influence the response to nicotine injection. It is concluded that the acceleration of mc wave frequency after nicotine administration is probably mediated via stimulation of nicotinic receptors on postganglionic parasympathetic nerve cells.

Adrenergic Agonists↗
PubMed1984

Mucolytic agents and mucociliary activity.

The three substances bromhexine, NA 872 (bromhexine metabolite VIII) and the beta 2-receptor agonist NAB 365 (clenbuterol) and their effect on the mucociliary activity have been studied in vivo in rabbits. The substances were given parenterally in increasing dosages and 519 records were obtained from 12 rabbits. Not even at dosages in excess of recommended human dosages has any effect on the mucociliary activity been observed for any of the substances during the first 30 minutes after administration. The conclusion to be drawn is that the three substances have no effect on the mucociliary activity in rabbit in vivo, but that this does not exclude an effect on mucociliary transport or clearance.

Adrenergic beta-Agonists↗
PubMed1982

Parasympathetic and sympathetic influences on mucociliary activity in vivo.

An in vivo test model has been developed to measure the influence of pharmacological substances on mucociliary activity in the rabbit maxillary sinus. Test solutions are administered via the feeding vessel to the investigated mucous membrane. The model permits administration of test substances and simultaneous recording of the obtained effects under conditions that closely mimic the normal situation. The parasympathomimetic agonist methacholine accelerates the mucociliary wave frequency dose-dependently. Atropine has no influence on the resting mucociliary activity but reduces or abolishes the effect of methacholine. The sympathomimetic beta 2-adrenoceptor agonist salbutamol accelerates the mucociliary activity dose-dependently whereas beta 1-adrenoceptor stimulation with prenalterol is without effect. Agonists acting on alpha 1- and alpha 2-adrenoceptors, phenylephrine and oxymetazoline, retard the mucociliary activity dose-dependently. beta- and alpha-adrenoceptor antagonists (propranolol and phentolamine, respectively) have no influence on the resting mucociliary activity but reduce the effect of beta- and alpha-adrenoceptor agonists, respectively. It is concluded that the resting mucociliary activity during anesthesia functions independently of parasympathetic and sympathetic nervous activity, and that the role of the parasympathetic and sympathetic innervation is to increase the mucociliary activity.

Animals↗
PubMed1982

Hemifacial spasm: electrophysiological findings and the therapeutic effect of facial nerve block.

Twenty patients with cryptogenic hemifacial spasm have been examined electrophysiologically and treated with blockade of the facial nerve with phenol injections after localization of the nerve by electrical stimulation. The electrophysiological findings suggested a central origin of the spasms. The phenol injections abolished the spasms, but they recurred in most patients after 6 to 12 months. A few patients appeared to get permanent relief after one or more phenol injections. We used phenol blockade of the facial nerve as our first therapeutic treatment of choice in patients with distressing hemifacial spasm because it is a safe, simple, and repeatable procedure.

Adult↗
PubMed1980

[The role of viral infection in sudden deafness (author's transl)].

A series of 35 patients with various degrees of sudden deafness were investigated in regard to recent or coexistent viral infection. The virological studies included 1) viral isolation by nasopharyngeal and faecal cultures; 2) viral serology for 20 different species of virus and the Paul Bunnel test; and 3) immunocomplex tests. In only two patients could a viral infection (a viral parotitis and an adenoviral infection) be proven (i.e. 6%). Immunocomplexes were found in 15 of 22 patients. Our studies, using conventional viral diagnostic tests, do not support the belief that viral infection is a common cause of sudden deafness. To solve the question whether viral infections play a part in the occurrence of sudden deafness these diagnostic aids must be complemented with modern immunological methods.

Adenoviridae Infections↗
PubMed1977

Intra- and extracellular activity of ciliated cells.

A method permitting simultaneous recording in vitro of the intracellular and extracellular ( = mucociliary) activity of respiratory ciliated mucous membrane is presented. Using this method the influence of different temperature levels (20 degrees, 30 degrees, 40 degrees C) upon the tracheal mucous membrane of 15 rabbits has been investigated. It is shown 1) that the extracellular ( = mucociliary) activity increases with rising temperatures whereas the intracellular activity is unaffected and remains constant, indicating a temperature influence upon the respiratory tract mucus rather than a change of the intracellular "pace-maker" mechanism; 2) that the restraining effect of the mucus decreases with rising temperatures but is still 10% of the intracellular frequency at body temperature; 3) that the presented method should be useful for future investigations concerning the effect of air-pollution and pharmacological substances upon respiratory mucous membranes.

Action Potentials↗
PubMed1976

Functional anatomy of the musculature of the trachea.

The smooth musculature of the human trachea was studied and compared with earlier observations in the rabbit. The results may be summarized as follows: 1. The annular m. constrictor tracheae, previously observed in the rabbit, has also been identified in the human trachea. 2. Longitudinal muscle fibers outside the constrictor musculature were observed in man. These fibers are rudimentary and appear to be of no functional importance. 3. From a functional point of view, it appears justified to regard the outer tracheal musculature largely as a constrictor musculature. 4. The main function of the outer musculature of the trachea and the elastic cartilaginous arches is to maintain the stability of the tracheal wall. 5. The variation of the lumen of the trachea is mainly controlled by the m. trachealis in the pars membranacea.

Animals↗
PubMed1975

The mucociliary activity of the upper respiratory tract.

A clinical in vivo - in vitro method for functional mucociliary studies via surface-light reflections is described as well as a method for intracellular recording of electrical activities in ciliated cells. Two types of surface-light reflections can be recognized - one from the secretion layer and one from the tops of lashing cilia. Internal and external cell activities als well as muco-rheological factors can be compared under the control of environmental influences such as air temperature, humidity and gas mixtures. The method can also be used for different clinical purposes.

Animals↗
PubMedDate not supplied

Mucociliary activity and the diving reflex.

It has previously been shown that mucociliary activity in the rabbit maxillary sinus is immediately increased after short-term exposure to such airway irritants as cigarette smoke and ammonia vapor. This increase is mediated through the stimulation of capsaicin-sensitive nerve endings. Besides producing the mucociliary effect, these irritants inhibit breathing, a response characteristic of the diving reflex in mammals. Whether an increase in mucociliary activity is part of the diving reflex was investigated by injecting 0.5 mL water into the nasopharynges of anesthetized rabbits. Mucociliary and respiratory responses were compared with the effects of mechanical stimulation (ie, rotating an intranasal catheter until sneezing occurred). Water challenge produced an increase in mucociliary activity of 21.6% +/- 2.4%, a response that began approximately 10 seconds after injection. Mucociliary acceleration was completely blocked by atropine, indicating a cholinergic mechanism, but was unaffected by pretreatment with capsaicin. The respiration rate was inhibited by about 45% after challenge with water. Pretreatment with atropine and capsaicin had no effect on this reduced respiratory rate. Mechanical stimulation of the nasal mucosa accelerated mucociliary activity. This response appeared approximately 4 seconds after stimulation was begun, and occurred simultaneously with the onset of sneezing. The peak increase was 22.0% +/- 2.1%. Sneezing was followed by an increase in the respiration rate of about 40%. Pretreatment with atropine or capsaicin had no effect on respiratory responses, but did inhibit mucociliary acceleration, suggesting that the response is mediated through cholinergic effector neurons after activation of capsaicin-sensitive nerve endings.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Air humidity and mucociliary activity.

The relationship between varying humidity levels in the surrounding air and the mucociliary activity in rabbit trachea has been investigated. At a relative humidity (R.H.) above 70% the risk for ciliestasis is very small in the temperature range between 34 C and 40 C. At 37 C ciliestasis is not obtained until a relative humidity (R.H.) of 50% has been reached. The critical border is reached already at 60% R.H. if the temperature is 40 C. At 37 C and a decrement from 90% to 60% R.H. the mucociliary wave frequency was reduced by 30%, but at 40 C the corresponding reduction was 60%.

Animals↗
PubMedDate not supplied

Effects of neuropeptides on mucociliary activity.

The effects of four neuropeptides, vasoactive intestinal polypeptide, enkephalin, bombesin, and substance P, on mucociliary activity in the rabbit maxillary sinus were investigated in vivo. The peptides were administered via the feeding artery (arteria maxillaris), and the resulting effects were registered with a noninvasive photoelectric technique. The peptides were tested in the dose range 0.0001 to 10 micrograms/kg body weight. The following results were observed: 1) vasoactive intestinal polypeptide and enkephalin did not influence mucociliary activity; 2) bombesin had only a slight accelerating effect on the mucociliary activity at doses of 0.1 to 10 micrograms/kg; and 3) substance P markedly accelerated the mucociliary activity in a dose-dependent manner in the dose range 0.01 to 10 micrograms/kg, the maximal increase being about 50%. The effect of substance P was atropine-resistant, and probably acted directly on the mucosa.

Animals↗