In the present study we investigated the possibility of central convergence of neural pathways coming from distant anatomical regions in modulating the cough response. We addressed this issue by inducing cough from the tracheo-bronchial region on the background of capsaicin-stimulated and mesocain-blocked nasal mucosa in 14 anesthetized guinea pigs. The control group consisted of 6 guinea pigs in which the active agents, capsaicin and mesocain, were substituted for by inert physiological saline. All animals were tracheostomized, and the larynx was disconnected from the proximal part of the trachea with preserved innervations, and all were subjected to the same protocol. Cough, induced by mechanical irritation of the tracheo-bronchial mucosa, was elicited three times: in the control condition, after intranasal capsaicin challenge, and after another capsaicin challenge preceded by intranasal instillation of a local anesthetic, mesocain. The main finding of the study was that the number of cough efforts per bout, assessed from positive deflections on the intrapleural pressure recordings, was significantly enhanced by intranasal capsaicin challenge and this effect was reversed by intranasal pretreatment with the anesthetic mesocain [2.1 ±0.2 (control) vs. 3.5 ±0.4 (capsaicin) vs. 2.2 ±0.2 (capsaicin after mesocain) (P<0.01)], with no appreciable changes in the magnitude of cough efforts. The cough response in the control group remained unchanged. We conclude that tracheo-bronchial cough may be modified by neural sensory input to the brain coming from nasal mucosa. Therefore, cough reflex is subject to central convergence of peripheral neural pathways originating at distant anatomical locations.
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Local counter current transfer of substances between venous and arterial vessels has been found in the perihypophyseal vascular complex after administration into the supraorbital vein. The present experiments investigate whether similar transfer could be found after nasal administration of testosterone. Experiments were conducted on the model of isolated pig's head perfused with autologous blood through one carotid artery. Tritium labelled testosterone was infused onto the nasal mucous. Radioactivity was measured in blood samples collected from the contralateral carotid artery (indicator of transfer), in the venous effluent from the jugular veins (indicator of absorption), and in tissue samples from the olfactory bulb, olfactory triangle, hypothalamus, mammillary body, cortex, pons, cerebellum, neurohypophysis, adenohypophysis, pia vessels and perihypophyseal vascular complex. The absorption was 11.4 ±4.6 per cent (mean ± SEM) and 0.4 ±0.3 per cent of the instilled testosterone was transferred during the 25 min collection period. The uptake of radioactivity was seen in many of the brain tissue samples representing the brain, pituitary, pia vessels and cavernous sinus - carotid rete complex, although a clear pattern was not seen. Nasally administered drugs may thus reach the brain in a relatively higher concentration than it reaches the rest of the body. This makes targeted treatment of the brain a distinct possibility. Additionally, the treatment will decrease the first-passage metabolism in the liver.
To determine the staphylococcal colonization pattern in healthy and diseased dogs, living in two particular environments, a number of microbiological samples were taken. Overall, twenty dogs, either healthy or with infected skin lesions, were examined. In each case bacterial swabs were collected from the nasal mucosa, ear, perineum, lumbo-sacralis triangle, and from the infection sites if such were present. A total number of 104 isolates representing different staphylococcal species were isolated and identified using routine biochemical methods applied in diagnostic laboratories. Among 17 isolated staphylococcal species, Staphylococcus intermedius was the most common species isolated from both healthy or diseased dogs living either in animal shelter or household environments. The pattern of Staphylococcus sp. colonization differs considerably for animals living in the two tested habitats. In particular, S. aureus MRSA and MSSA isolates were detected only in infected skin lesion samples from animals that dwelled in the animal shelter. As could be expected, S. intermedius was found to be a predominant causative agent in canine skin infections. In our study, we demonstrated that S. intermedius in its carrier-state, inhabits mainly the mucosal membrane of the nasal vestibule. It was also found in the samples taken from the skin, the lumbo-sacralis triangle and perineum, but was rarely isolated from the ears.