Biomedical subjects
Publications and source records attributed to R Serra.
The authors analyze present-day rapid laboratory methods that are helpful in the diagnosis of various critical states in infectious diseases. Currently the immunologic and other than immunologic methods for visual detection of corpuscular antigens, soluble antigens in clinical material are the best rapid methods easy to perform. Methods with DNA probes are a promising alternative of these methods.
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Extracellular single neuron recording in nucleus ambiguus demonstrates the existence of different neuronal classes within its electrophysiological limits. Laryngeal motoneurons were identified by their antidromic activation from the recurrent laryngeal and vagus nerves. Interneurons were identified by their antidromic activation from the contralateral cervical spinal cord. Stimulation of the ipsilateral superior laryngeal nerve activated synaptically all laryngeal motoneurons recorded but not interneurons. Most motoneurons and all interneurons showed spontaneous discharges during the inspiratory phase of the respiratory cycle. A few expiratory motoneurons were also recorded. In addition to laryngeal motoneurons and interneurons vagal stimulation also activated a population of efferent neurons located in the nucleus ambiguus with firing patterns not related to respiration. Functional implications of described findings are discussed.
In eight asthmatic and six normal subjects serum terbutaline concentrations were correlated with changes in FEV1, MEF50%, Gaw, sGaw, and plasma cAMP concentrations after administration of 0.5 mg terbutaline subcutaneously, 5 mg orally, and an oral placebo. In asthmatics and normals the changes in serum terbutaline levels and plasma cAMP levels were closely correlated and in the same range. No change in lung function parameters was registered in normals, whereas in asthmatics a significant improvement was shown. In asthmatics all lung function parameters closely parallelled the changes in serum terbutaline concentrations and cAMP plasma concentrations, the FEV1 being the least variable lung function parameter. The maximal effect in FEV1 occurred 30-60 min after the subcutaneous dose and 2-4 h after the oral dose. The FEV1 improvement showed a linear relationship with the serum terbutaline concentration between 1.6 and 6 ng/ml. In contrast with theophyllines and anticholinergics, serum terbutaline concentrations showed a very low interindividual variance. Nevertheless it appeared that prediction of a certain improvement in lung function was not possible on the basis of the serum concentration. Since changes in plasma cAMP values after terbutaline therapy were similar in normals and asthmatics, the lung function improvement in the asthmatics suggests that if a beta-adrenergic defect exists, this must be mainly situated in the lung tissue.
Modern methods make it possible to measure respiratory parameters as VE, respiratory frequency, VO2 and delta O2% and circulatory parameters as heart rate and oxygen pulse in very difficult conditions. Very recently these parameters were measured continuously on mineworkers at work in a tailgate stable hole for the first time. These measures were completed by physiological evaluations with the same methods on the same subjects during exercise in a lung function laboratory or in a simulation chamber with different conditions of humidity and temperature.
Several functional parameters can be used to define respiratory dysfunctions. Many of these variables provide specific information about particular physiopathologic phenomena, but they seldom provide a general overview of the ventilatory function. Nevertheless, both pharmacologic and epidemiologic research need functional parameters that precisely specify the respiratory defect. The new parameter we discuss takes into account the variations in volumes as related to flow variations: it is the product of two traditional spirometric parameters (FEV1 X MMEF). This value gives information on the patient's capacity to exhale air from the lungs for a fixed variation of intrathoracic pressure as well as data on the acceleration pattern of the expired volume in 1 s, hence the name, acceleration index (AI). AI was used to predict bronchodilation in two groups of patients with severe airway flow limitations. On the basis of our findings three conclusions can be drawn. This new spirometric parameter provides an inexpensive and rapid means of obtaining a highly sensitive definition of the patient's respiratory dysfunction which is useful in screening patients. Applied to patients with severe airways obstruction, AI can be used to immediately predict the reversibility of air flow limitation and then to define the limits of the activity of bronchodilators. Finally, a basal value of AI below 1.000 l/s-1 indicates the probable irreversibility of the airways obstruction, regardless of drug or route of administration. Such cases suggest a prevailing picture of emphysema rather than reversible bronchospasm.
The spontaneous and visually induced activity of abducens motoneurons has been recorded in the alert cat. Motoneurons were identified by their antidromic activation from the ipsilateral abducens nerve. All identified motoneurons appeared related to both the position and velocity of the eye in the horizontal plane, although distributed in a wide range. Neural time constants were also measured, showing a mean value similar to that of the mechanical time constant of the oculomotor plant. According to present results, abducens motoneurons of cats and monkeys are very similar, notwithstanding some differences in their activities during saccadic movements.
A new simple spirometric parameter for predicting the reversibility of bronchial obstruction is evaluated in two homogeneous groups of severe COLD patients. By combining FEV1 and MMEF, this index is practically the product of the volume expired in 1s and the corresponding flow at 50% of FVC which characterizes the emptying pattern. The parameter provides a useful method for verifying the patient's responsiveness to beta 2-bronchodilator drugs. The bronchial flow limitation depends more on the airways obstruction present than on the characteristics of the drugs administered. A threshold level for the new parameter was defined (1000 l/s); beneath this value responsiveness to beta 2 drugs must be considered practically negligible.
Six normals and six patients with chronic obstructive lung disease were treated with a short- and long-acting theophylline (Theolair and Theolair retard). During treatment the lung function data of the patients showed an improvement on day 1, but no further improvement on days 4 and 7, despite the higher theophylline plasma concentration on these last days. There was no close correlation between the improvement of lung function and the theophylline plasma concentration, nor was there any difference between Theolair and Theolair retard as regards improvement of lung function. Side effects were negligible, and the theophylline plasma concentration was rather low. It seems advisable to use a higher dosage of the theophyllines and perhaps it is even better to combine them with other bronchodilators.
The electrophysiology of abducens nucleus antidromic field potentials from onset of peripheral axotomy up to reinnervation has been studied in the alert cat. Nerve section induced a reduction of 80% in the amplitude of the antidromic field potential. This reduction began from 2 to 5 days after axotomy and returned to control values from 20 to 30 days later, in parallel with recovery of oculomotor function. During the critical chromatolytic period, the latency of the antidromic potentials increased, while the amplitude of the antidromic field potential could be easily modified by adequate visual and/or vestibular stimulation. In contrast to control motoneurons, axotomized cells showed a noticeable variability in their activation latency, as well as a higher threshold for the antidromic invasion of the IS-SD compartments.
The spontaneous and the visual and vestibular induced activity of axotomized abducens motoneurons (ABD Mns) has been recorded in alert cats. Axotomy was carried out peripherally in the ocular orbit. ABD Mns were identified by their antidromic activation from the VIth nerve. Control Mns showed a clear relationship with eye position and velocity in the horizontal plane, whereas axotomized Mns showed a remarkable variability in their antidromic activation, a rapid fatigability during eye fixations and a decreased sensibility to eye velocity. Occasionally, axotomized Mns fired a short burst of activity before saccades in the off-direction. Functional involvements of described findings are discussed.
Field potentials in the ambiguous nucleus induced by stimulation of the recurrent, superior laryngeal and vagus nerves have been recorded in the anesthetized cat. Stimulation of the ipsilateral recurrent nerve induced a positive-negative-positive antidromic field potential in the ambiguous nucleus indicating a close-field organization of laryngeal motoneurons, which showed a preferential projection of their dendritic trees in dorso-medial and ventro-lateral directions. Superior laryngeal nerve stimulation induced the sequential synaptic activation of laryngeal motoneurons. Besides laryngeal motoneurons activation, stimulation of the vagus nerve also induced the antidromic invasion of a distinct population of efferent neurons with a latency longer than those of laryngeal motoneurons.
Eight patients with obstructive airways disease with a reversible component were treated with incremental doses of terbutaline by a Monaghan type nebulizer. Accumulative doses up to 3 mg were tolerated without significant side effects. Terbutaline appears to be safe and effective drug when administered by IPPB.
Preoperative respiratory evaluation is examined in the light of factors likely to influence the conduct of the operation and its subsequent course. The methods required for this purpose are reviewed. Attention is first given to changes in specific respiratory components (alveolar exchange surface area, ventilation, diffusion and circulation) and their associated activities (chest mechanics, pulmonary circulation, motor nervous system), and those dependent on the type of surgery (lung, chest, abdomen, other parts). Next, the measurement methods available, the criteria for evaluating the data, and the criteria whereby candidates are selected for emergency surgery, surgery after thorough checking and extensive examination, general surgery, and chest surgery are explained. Lastly, the specific case of patients with typically respiratory diseases is discussed.
The management of chronic nonspecific lung disease (CNSLD) is a complex matter, influenced by different etiopathogenetic and physiopathological mechanisms. The most significant of these mechanisms have been revealed. Of the different function examinations the respiratory gas analysis appears to be particularly useful in obtaining detailed information. However, the choice of medication still remains of utmost importance. This paper presents a review of the selection criteria for antibiotics, bronchodilator drugs, theophylline derivatives, beta-sympathicomimetics, atropine corticoids, desensitizing substances together with the indication for a correct oxygen therapy.
The activity of abducens and accessory abducens motoneurons (Mns) has been recorded during spontaneous and vestibularly or visually induced eye movements in awake cats. Motoneuronal activity was also recorded during corneal reflexes induced by the excitation of trigeminal terminals in the orbit. Recorded Mns were antidromically identified by electrical stimulation of the VI nerve. Accessory abducens Mns showed a burst of activity in response to trigeminal stimulation, but they did not show any response in relation to horizontal, vertical and/or oblique eye movements. On the contrary, abducens Mns firing activities were related to the position and velocity of the eye in the horizontal plane, without showing any change in their firing patterns in response to trigeminal stimulation in the orbit.
One of the authors observed an excess of dyspnea complaints in coalminers without bronchitis, massive fibrosis or emphysema in different epidemiological surveys. An abnormally high prevalence of dyspnea complaints in coalminers has also been reported by other investigators in different countries. It seems therefore necessary to study whether the type of complaints observed in our country can be validated by appropriate functional investigations. A research on this problem is in progress in our laboratory. In this preliminary publication a review of the literature concerning the mechanisms of dyspnea is presented. Such a study was necessary in order to make an adequate choice of the functional measurements usable for our validation study.