Corticofugal modulation of the information processing in the auditory thalamus of the cat

Summary Single unit activity of 355 cells was recorded in the auditory thalamus of anesthetized cats before, during, and after the inactivation by cooling of the ipsilateral primary auditory cortex (AI). Most of the units (n = 288) showed similar functional characteristics of firing before and after the cryogenic blockade of AI. The spontaneous firing rate remained unchanged by cooling in 20% of the units and decreased in the majority of them (60%). In some regions, i.e. dorsal division of the medial geniculate body (MGB), lateral part of the posterior group of the thalamus, and auditory sector of the reticular nucleus of the thalamus, the maximum firing rate evoked by white noise bursts was generally affected by cooling in the same direction and to the same extent as the spontaneous activity. Units in the ventral division of MGB showed a characteristic increase of signal-to-noise ratio during cortical cooling. The corticofugal modulation led to the appearance or disappearance of the best frequency of tuning in 51 units and changed it by more than 0.5 octave in 34 units. The bandwidths of different response patterns to pure tones stimulation were used to define a set of functional properties. During cryogenic blockade of AI, two cortically modulated sub-populations of units were usually distinguished that exhibited changes for a given functional property. The complexity and diversity of the effects of cortical inactivation suggest that the corticothalamic projection may be the support for selective operations such as an adaptive filtering of the incoming acoustic signal at the thalamic level adjusted as a function of cortical activity.     

Substance P and human nasal mucociliary activity

Summary Substance P (SP), a potent inflammatory agent, has been found in sensory nerve fibres in the nasal mucosa in several experimental animals as well as in man. It may participate in the inflammatory response as part of the mucosal defence against foreign materials. In experimental animals SP has been found to increase mucociliary in airway mucosa. The present study was performed in order to find out the relationship between topically applied SP and nasal mucociliary function in humans. Thirteen healthy volunteers were challenged with 65 µg SP or placebo in a randomized cross over fashion and mucociliary transport time was determined each time using the saccharine dye test. The dose of SP was chosen after an open dose-response study. No statistically significant change in the mucociliary transport time was found after challenge with SP as compared to placebo. The possible reasons for this are discussed.     

Leakage of carbonic anhydrase III from normal and denervated rat skeletal muscle following contractile activity.

Skeletal muscle extracellular carbonic anhydrase III was investigated in anesthetized rats by a microdialysis technique. A small dialysis probe was inserted into the tibialis anterior (TA) muscle and perfused continuously. Perfusates were collected before and during muscle contraction, induced by electrical stimulation of the muscle or of the sciatic nerve. In the perfusate of resting normal and denervated muscle, the concentration of CA III was 10 to 12 ng/mL, as measured by a radioimmunosorbent technique. During contractile activity, the concentrations of CA III increased markedly in the normal and denervated muscle. A TA muscle suspended in physiological saline behaved similarly, even though the leakage before and during contraction was higher than in vivo. The results show that skeletal muscle leaks CA III both in vivo and in vitro, a leakage which was markedly increased by contractile activity. The microdialysis technique should also be useful in humans to study the efflux of various proteins from different kinds of diseased or fatigued muscles.     

Activity of lateral vestibular nucleus neurons during locomotion in the decerebrate Guinea pig

Summary The influence of locomotor activity upon neurons in the lateral vestibular nucleus was investigated in precollicularly-postmamillary decerebrate guinea pigs. Out of 95 recorded neurons, 24 were identified as vestibulospinal and 71 had no descending projections. Locomotor activity occurred either spontaneously or was prompted by electrical stimulation of the mesencephalic locomotor region. Natural vestibular stimulation was supplied by tilting the animal about its longitudinal axis. Locomotor rhythmic limb muscle activity was accompanied by an increase in the firing frequency in the vast majority of investigated neurons. The increase in frequency was observed at the beginning of ipsilateral forelimb extensor muscle activity. Only in a few non-vestibulospinal neurons was the spontaneous activity depressed during locomotion. An increase in evoked responses was observed in almost all vestibulospinal neurons and in two thirds of the neurons without descending projections. A decrease in evoked responses was observed in one quarter of non-vestibulospinal neurons. During locomotion, the mean and maximal frequencies of evoked neuronal impulse activity changed, but the phase lag of these changes was not altered significantly. The results suggest an enhancement of vestibulospinal influences during locomotion, thus providing a high level of tonus in antigravitational muscles. This is interpreted as a mechanism to ensure that equilibrium is maintained during motion in different gaits and postures.     

Soluble CD14 but not interleukin-6 is a new marker for clinical activity in atopic dermatitis

Summary Levels of soluble IL-2 receptors, IL-6, soluble CD23, soluble CD14 and ECP (eosinophilic cationic protein) were measured as markers of T-cell, B-cell, monocyte and eosinophilic leucocyte activation in 26 patients with atopic dermatitis (AD) on admission to (A) and at discharge from (D) the Department of Dermatology in Zurich. The serum levels of sIL-2R, IL-6, sCD23, sCD14 and ECP were significantly elevated in AD patients in comparison with the normal values of healthy donors. A significant decrease in sIL-2R (p=0.0093) and in sCD14 (p=0.0134) levels was demonstrated between A and D, correlating with the improvement in the skin intensity score (SIS). In addition, a significant correlation of the sCD14 levels and the SIS at A was demonstrated (p=0.0415). These results also incriminate monocytes in the pathogenesis of AD, indicating that, besides sIL-2R and ECP, SCD14 could also be a possible marker for the disease activity.     

Influence of acetylcholine on neuronal activity of monkey amygdala during bar press feeding behavior

Single neuron activity in the monkey amygdala was investigated during cue signalled conditioned bar press feeding behavior and the effects of electrophoretically applied acetylcholine (ACh) and atropine were analyzed. ACh increased the firing rate of one third of the neurons tested; these excitatory responses were inhibited by the muscarinic receptor antagonist atropine. No characteristic location of ACh-sensitive neurons was found, cells were diffusely distributed throughout the amygdala. Activity of ACh-sensitive neurons did not correlate with any particular event during the bar press feeding task. However, continuous application of ACh at low current intensity during the task significantly enhanced the task-related excitatory firing patterns, or markedly attenuated the inhibitory responses. Continuous application of atropine elicited or enhanced inhibitory response patterns. These results suggest that the cholinergic system of the monkey amygdala facilitates neuronal excitation but attenuates inhibition related to various phases of feeding behavior, such as to cue recognition, food aquisition and rewarding process.     

Primary Aldosteronism

ABSTRACT A follow-up examination was performed one month to 20 years after adrenalectomy in 28 cases with surgically treated primary aldosteronism due to adrenal adenoma. The mean age at diagnosis was 45, and the mean duration of hypertension seven years. Severe hypertension with a diastolic blood pressure of 130 mmHg or more was observed in 35%. Postoperatively cerebrovascular catastrophe developed in two cases, both of which belonged to the group of patients with severe hypertension. Normalization of blood pressure was observed in 70% and in the remaining subjects the blood pressure was lower than at diagnosis. The blood pressure response to adrenalectomy appeared unpredictable in view of such parameters as the initial blood pressure, age at diagnosis, and duration of the hypertensive state. Toxicosis during pregnancy and metrorrhagia was observed with unexpectedly high frequency in this study population. Low ambulatory plasma renin activity was recorded at the follow-up in 15 out of 18 subjects studied in the absence of evidence of hyperaldosteronism.     

Aromatic ethers of 1-aryl 2-(1H-azolyl)ethanol: study of antifungal activity

Aromatic ethers related to antifungal azole miconazole were synthesized and tested against various strains of Candida. We found that activity is related to the nature of the aromatic ring and the position of substituents on this ring. Activity is more strongly dependent on the substituent in the 2 position of the ethyl chain than on the aromatic group linked through the oxygen. Triazoles were always less potent than the corresponding imidazole analogues.     

Analgesic actions of dynorphin A(1–13) antiserum in the rat brain stem

This study was performed to evaluate the effects of dynorphin A(1–13) antiserum when microinjected into an active hyperalgesic region within the rat brain stem. When administered within the dorsal posterior mesencephalic tegmentum (DPMT) of intact conscious rats, dynorphin A(1–13) antiserum produced rapid onset and persistent prolongation of a low intensity thermally evoked tail avoidance response (LITETAR). These analgesic actions of the dynorphin A(1–13) antiserum appeared to be dose dependent. These studies support previous hypotheses about the existence of tonically active brain stem opioid hyperalgesic processes. Further, the results provide indirect evidence for a potential role of brain stem dynorphin(s) in facilitating pain.