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Biomedical subjects

J Souhrada

Publications and source records attributed to J Souhrada.

10 recordsLinked to original sources
PubMed1978

Bronchoconstrictive suggestion in asthma: a role for airways hyperreactivity and emotions.

Using whole-body plethysmographic measurements, asthmatic patients inhaled aerosolized saline presented either as a neutral substance (day 1) or in the guise of a bronchoconstrictor (day 2). Bronchoconstrictive suggestion resulted in increased airway resistance and decreased specific airway conductance, whereas thoracic gas volume was unchanged. The variation in the response was analyzed in relation to airways hyperreactivity, as indexed by methacholine and histamine inhalation challenges, and physiologic measures of the emotional reaction to bronchoconstrictive suggestion, as indexed by changes in blood pressure, heart rate, finger pulse amplitude, and forehead electromyographic activity. It was found that the bronchoconstrictive response was significantly related to the degree of airways hyperreactivity and to the emotional response. These results suggest that asthmatic patients apt to respond to bronchoconstrictive suggestion with airways obstructions are characterized by highly hyperreactive airways. Responders also appear to be emotionally labile, although it is not yet clear whether the emotional response per se evokes airway obstruction or is merely a by-product of the occurrence of airway obstruction.

Adolescent↗
PubMed1976

Response of asthmatics to methacholine and suggestion.

Effects of diluent, methacholine, and suggestion on pulmonary function were studied in 9 asthmatic subjects. On day 1, flavored diluent was given as a control preparation. On day 2, increasing concentrations of similarly flavored methacholine were administered. On day 3, the effect of flavored diluent plus suggestion was studied. Although all variables were affected, the dose-response relationships for methacholine were most pronounced for specific airway conductance and airway resistance, in contrast to maximal mid-expiratory flow, forced expiratory volume in 1 sec, and forced vital capacity. Suggestion toward bronchoconstriction significantly affected only the plethysmographic parameters, specific airway conductance, and airway resistance, and not the spirometric variables. Both airway resistance and 1-sec forced expiratory volume showed slight, but significant, changes as a result of bronchodilator suggestion, which was used to overcome the suggestion toward bronchoconstriction. Because suggestion had a greater effect on large airways than peripheral airways, a role for the vagus is implied. Thus, any protocol using body plethysmography must consider a possible effect of suggestion on results.

Adolescent↗
PubMed1976

Reversible restrictive lung disease stimulating asthma.

A young adult woman presented with spontaneous and exercise-induced episodic dyspnea without wheezing. During dyspneic episodes all static lung volumes decreased markedly, the inspiratory capacity fell from 3.0 to 1.1 litres and total lung capacity from 5.3 to 2.6 litres. Airway resistance (Raw) remained normal, and maximal expiratory flows at low absolute lung volume actually increased. Static compliance decreased from 0.153 to 0.077 litre/cmH2O, and the elastic recoil increased from 2.8 to 4.8 cmH2O at 50% of baseline total lung capacity when dyspneic. Upstream airway resistance (Rus) remained unchanged, 1.7 cmH2O/litre/sec. All physiologic variables indicated a reversible restrictive process exists, the origin of which is unclear. It is concluded that the episodic increase in elastic recoil properties results in [1] loss of volume primarily in the alveolar ducts and sacs, [2] preservation of normal Rus by an increase in driving pressure, and [3] maintenance of normal Raw by stabilization of larger airways.

Adult↗
PubMedDate not supplied

Effects of renal neutral endopeptidase inhibition on sodium excretion, renal hemodynamics and neurohormonal activation in patients with congestive heart failure.

We investigated the effects of inhibiting endogenous atrial natriuretic factor (ANF) metabolism on renal hemodynamics, sodium excretion and neurohormones in 12 patients with New York Heart Association functional class II congestive heart failure (CHF) due to left ventricular systolic dysfunction. In a randomized, placebo-controlled, double-blinded fashion, 8 patients received a single oral dose of candoxatril, an inhibitor of renal neutral endopeptidase, and 4 patients received placebo. Candoxatril treatment increased plasma ANF by 70 +/- 71 pg/ml (p < 0.015 vs. placebo) and plasma cGMP by 7.9 +/- 2.7 pmol/ml (p < 0.001 vs. placebo), with maximal effects at 3.5 h. Urinary cGMP more than doubled (p = 0.025 vs. placebo). Candoxatril increased urinary sodium by 2.7 +/- 2.0 mEq/h (p < 0.05 vs. placebo) and significantly elevated filtration fraction with no significant effect on glomerular filtration rate, renal plasma flow or lithium clearance. A significant reduction in aldosterone concentration with a similar trend in plasma renin activity was noted in candoxatril-treated patients. Thus in patients with moderate heart failure, renal neutral endopeptidase inhibition increases urinary sodium excretion. The lack of an effect on renal hemodynamics suggests that this natriuresis results from ANF-mediated inhibition of tubular sodium reabsorption. These findings justify additional investigation into potential clinical benefit of endopeptidase inhibition in patients with CHF.

Adult↗