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Biomedical subjects

G Scano

Publications and source records attributed to G Scano.

At least 109 records · Page 6Linked to original sources
PubMed1989

Neural respiratory drive and neuromuscular coupling during CO2 rebreathing in patients with chronic interstitial lung disease.

In 12 patients with CILD and 18 age-matched normal subjects we assessed the ventilatory control system at three levels: (a) neural, as assessed by EMGd (XP/Ti) and EMGint muscles via surface electrodes; (b) muscular, as assessed by mouth occlusion pressure (P0.1); and (c) ventilatory, as assessed by both ventilation (VE) and the related parameters, tidal volume (VT) and respiratory frequency (f). Compared with a normal control group, patients exhibited a significant decrease in lung volumes and in MIP; VT and inspiratory time (Ti) were significantly lower, while VT/Ti, P0.1, and both EMGd and EMGint were significantly greater in patients. During a CO2 rebreathing test, patients exhibited significantly greater EMGd, EMGint, and P0.1 responses to increasing PETCO2 than the control group. VE response slopes were similar in the two groups. For a given EMGd response slope (delta XP/Ti/delta PETCO2), the average P0.1 response slope (delta P0.1/delta PETCO2) was found to be significantly lower in patients than in the normal control group. Compared with normal subjects, CILD patients have a normal or increased neural component of respiratory activity and relatively low neuromuscular coupling (delta P0.1/delta XP/Ti). The decreased neuromuscular coupling could be explained in these patients by a reduced inspiratory muscle strength.

Aged↗
PubMed1988

Influence of exercise and CO2 on breathing pattern in patients with chronic obstructive lung disease (COLD).

In ten eucapnic patients with chronic obstructive lung disease (COLD) we evaluated the breathing pattern during induced progressive hypercapnia (CO2 rebreathing) and progressive exercise on an ergometric bicycle (30 W/3 min). The time and volume components of the respiratory cycle were measured breath by breath. When compared to hypercapnia, the increase in ventilation (VE) during exercise was associated with a smaller increase in tidal volume (VT) and a greater increase in respiratory frequency (fR). Plots of tidal volume (VT) against both inspiratory time (TI) and expiratory time (TE) showed a greater decrease in both TI and TE during exercise than with hypercapnia. Analysis of VE in terms of flow (VT/TI) and timing (TI/TT) showed VE to increase by a similar increase to that in VT/TI during both exercise and hypercapnia, while TI/TT did not change significantly. When the patients were matched for a given VE (28 l.min-1), exercise induced a smaller increase in VT (p less than 0.05), a greater increase in fR (p less than 0.025); TI (p less than 0.025) and TE (p less than 0.01) were found to be smaller during exercise than hypercapnia. The change in the off-switch mechanism during exercise and hypercapnia could account for our results.

Adult↗
PubMed1988

Changes in neural drive (EMGd) and neuromuscular coupling during histamine-induced bronchoconstriction in patients with asthma.

This study was undertaken in order to assess the neural drive to the respiratory muscles and the inspiratory neuromuscular coupling in patients with bronchial asthma during histamine-induced bronchoconstriction. Bronchoconstriction was produced in a graded fashion, with histamine phosphate aerosol of increasing dose, in twelve asymptomatic asthmatic patients and was measured by FEV1. Inspiratory drive was measured by electromyographic activity of the diaphragm (EMGd) and the coupling of the neural drive to the respiratory muscles was assessed by the relationship of mouth occlusion pressure (P0.1) to EMGd. During the test we also measured electromyographic activity of the inspiratory intercostal (EMGint), sternomastoid (EMGsm) and expiratory abdominal (EMGab) muscles. Histamine caused a significant decrease in FEV1, a significant increase in P0.1, EMGd, EMGint, and a relevant increase in EMGsm, with no substantial increase in EMGab. An inverse significant relationship between the change in FEV1 and changes in P0.1, EMGd and EMGint and a significant correlation between the change in FEV1 and in the P0.1/EMGd ratio were observed. We conclude that a progressive increase in bronchospasm is accompanied by a progressive increase in respiratory neural drive and decrease in neuromuscular coupling. This could be caused both by an increase in lung volume and a lack of abdominal expiratory muscle recruitment.

Adult↗
PubMed1987

Effects of aminophylline on respiratory drive and neuromuscular coupling in normal man and in patients with chronic airflow obstruction.

In order to evaluate the separate effects of aminophylline on the neural and muscular components of the respiratory control system, assessed by electromyographic activity of the diaphragm (EMGd) and mouth occlusion pressure (P0.1), respectively, 6 normal subjects and 14 patients with mild or moderate chronic airflow obstruction (8 asthmatics and 6 COPD) were studied during CO2 rebreathing, before and after administration of a therapeutic dose of aminophylline 5.6 mg/kg. Compared to normal subjects, before aminophylline administration both asthmatic and COPD patients exhibited a significantly greater value in EMGd response slope to CO2. In no group did aminophylline modify P0.1 or EMGd activity response slope to CO2, nor did it significantly affect neuromuscular coupling, assessed by plotting change in P0.1 against change in EMGd activity with increasing CO2. The data appear to indicate that aminophylline in therapeutic concentrations does not modify respiratory drive or neuromuscular coupling in normal subjects, or in patients with mild or moderate chronic airflow obstruction.

Action Potentials↗
PubMed1987

Effect of inhaled histamine on occlusion pressure and breathing pattern in asthmatic patients.

In animals, histamine inhalation is known to increase either respiratory frequency or respiratory drive by stimulation of airway vagal sensitive endings. However, it is not well known whether these changes are concomitant in man. In order to elucidate this point, we carried out the present investigation in thirty-five asthmatic patients who underwent bronchial provocation test by progressively doubling the dose of inhaled histamine. Bronchial reactivity to histamine allowed two populations of patients to be defined: group I with moderate and group II with mild, increased reactivity. In the twenty-three group I patients, neuromuscular inspiratory drive, assessed by mouth occlusion pressure (P0.1), was found to be significantly increased while no significant changes in breathing pattern were noted. In the twelve group II patients histamine did not modify P0.1 or breathing pattern. However, we were able to separate in group I a sub-group of ten patients, as with atopic asthma, in which histamine-induced increase in P0.1 was paralleled by rapid and shallow breathing (RSB). Changes in P0.1 and breathing pattern did not depend on baseline airway calibre. In group I, after bronchoconstriction had been reversed by inhaling a beta 2-agonist bronchodilator agent (fenoterol), P0.1 decreased significantly and RSB was found to be reversed; however, these changes were not interrelated. We concluded that: in asthmatics, histamine-induced increase in P0.1 is not necessarily paralleled by, nor related with, change in breathing pattern and in atopics a 'sensitization' of vagal receptors could account for the concomitance of enhanced P0.1 with RSB.

Administration, Inhalation↗
PubMed1987

Characterization of specific immune complexes in HIV-related disorders.

Eighty-seven seropositive subjects with HIV (human immunodeficiency virus) infection together with 20 normal controls with no history of any illness were investigated for the presence of circulating immune complexes (CIC) by the conglutinin binding assay (KgBA) and further studied for isotype characterization of CIC. Six out of 87 patients showing very high values for immune complexes (CIC) were studied for the presence of free antigen. In 3 out of 6 (1, IVc1; 1, III; 1, IVa) we could detect by ultracentrifugation analysis the presence of specific HIV (p15) anti-HIV (anti-p15) and gp41-anti-gp41 CIC. Evidence in favour of this finding is supported by: the presence of specific CIC (p15-anti-p15 or gp41-anti-gp41) seen only at pH 7.2; the apparent presence of free antigen and specific HIV antibodies were only at pH 4.0. The relevance of this finding lies in the attempt to explain the occurrence of false seronegativity seen occasionally in symptomatic patients. Thus, the presence of CIC might perhaps interfere in the routine assay (i.e. ELISA) making the diagnosis difficult. All these considerations will have to be taken into account in the future handling of this disease.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Inspiratory impedance during histamine-induced bronchoconstriction in patients with bronchial asthma.

Histamine inhalation provocation tests were performed in 18 asymptomatic asthmatic patients with progressively increasing doses of a pressurized aerosol of histamine phosphate. Forced expiratory volume in 1 s (FEV1), total neuromuscular output, assessed by mouth occlusion pressure (P0.1), mean inspiratory flow (VT/Ti), and the P0.1/(VT/Ti) ratio, which represents an index of effective inspiratory impedance of the respiratory system, were measured. With histamine, compared to control, FEV1 decreased and P0.1/(VT/Ti) increased (p less than 0.01 for both). After bronchoconstriction was reversed by administration of a beta 2-agonist bronchodilator (fenoterol), a significant decrease in P0.1/(VT/Ti) (p less than 0.001) and a significant increase in FEV1 (p less than 0.01) were noted as compared to histamine. With histamine, change in P0.1/(VT/Ti) was found to be related to its pre-histamine value (p less than 0.01). Furthermore, with histamine and fenoterol, changes in P0.1/(VT/Ti) and concurrent changes in FEV1 were found to be significantly related (p less than 0.001). From these data we calculated that the P0.1/(VT/Ti) ratio provides a useful tool in the clinical assessment of histamine-induced bronchospasm.

Adult↗
PubMed1986

HTLV-III seropositivity in symptom-free Italian haemophiliacs. Correlation with consumption of commercial concentrate and abnormalities of T and B lymphocytes.

Various immunological parameters exploring both T- and B-cell functions were determined in a group of 74 symptom-free Italian haemophiliacs treated with commercial concentrate imported from the USA and were correlated with the presence in their serum of antibody to HTLV-III. There was a strong correlation between HTLV-III seropositivity and the amount of concentrate consumed. A significant correlation between HTLV-III seropositivity and T-cell alterations, such as T4/T8 ratio less than 1 and reduction in the absolute number of T4+ lymphocytes, or B-cell alterations such as hypergammaglobulinaemia and enhanced spontaneous IgG synthesis in vitro, was also observed.

Antibodies, Viral↗
PubMed1986

Functional evaluation in stage I pulmonary sarcoidosis.

A functional evaluation was performed in 9 non-smoking patients suffering from sarcoidosis characterized, on chest roentgenograms, by hilar adenopathies (stage I). Frequency dependence of compliance (5 cases) and decreased conductance of the upstream segment (3 cases) were the major findings. From this it is concluded that, even at stage I, small-airway impairment may be documented in some patients, suggesting the existence of peribronchiolar granulomatous infiltration.

Adult↗
PubMed1986

Breathing pattern and neuromuscular drive during CO2 rebreathing in normal man and in patients with COPD.

In 11 normal subjects and in 10 patients with chronic obstructive pulmonary disease we evaluated breathing pattern and mouth occlusion pressure (PO.1), while breathing room air and during reinhalation of a hypercapnic hyperoxic gas mixture. In the breathing pattern we analyzed the time and volume components of the respiratory cycle: tidal volume (VT), inspiratory time (Ti), expiratory time (Te), total time of respiratory cycle (Ttot); mean inspiratory flow (VT/Ti) and Ti/Ttot ratios, respiratory frequency (RF) and instantaneous ventilation (VE). In the normal subjects, increase in VE during rebreathing mainly depended on an increase in both VT and VT/Ti without significant changes in Ti. During CO2 rebreathing the patients exhibited a lesser increase in VE compared to normals, due to a lesser increase in VT. However, expressing VT in percent of resting inspiratory capacity showed that VT attained at the end of rebreathing (VTmax) was similar to that noted in the normal subjects at the same minute of rebreathing. Furthermore, percent increase in VE, VT, VT/Ti and PO.1 between resting value and that at 56 mm Hg (delta %), were significant in both groups with a major increase in the normal subjects for VE and VT/Ti. In comparison, delta % decreases in both Te and Ttot were found to be significant only in the normal subjects. VT/Ti was related to VE in a similar way in the two groups. In contrast, in the normal subjects, Ti/Ttot did not increase with increasing VE. During rebreathing increase in PO.1 was found to be similar in the normal subjects and in patients. However, for a given neuromuscular drive VE and VT/Ti were greater in the normal subjects than in the patients. These data show that in the patients as a whole no significant changes in breath intervals occur during CO2 rebreathing. Furthermore, in patients, in spite of a similar increase in neuromuscular drive, the efficiency by which inspiratory muscle output (PO.1) is converted into VT/Ti was found to be reduced.

Adult↗
PubMed1986

Effects of histamine and reproterol inhalation on mouth occlusion pressure in patients with bronchial asthma.

Both vagal and non-vagal afferences from the lung or chest wall contribute to increasing neural drive to the respiratory muscles, but only the former are known to change the breathing pattern by increasing respiratory frequency (RF) during bronchoconstriction. In order to evaluate the relative contribution of vagal and non-vagal afferences to increasing neural drive to the respiratory muscles in 14 asymptomatic asthmatic patients known to be responsive (decrease in FEV1 greater than 20% of the control values) to previous bronchial provocation test (BPT) with aerosolized histamine, we evaluated FEV1, breathing pattern and neuromuscular drive, as assessed by mouth occlusion pressure (PO.1), under control conditions, during BPT with progressive doubling doses of inhaled histamine (H) and 5 min after inhalation of a bronchodilator agent (Reproterol) (B). During HBPT FEV1 exhibited a significant decrease (p less than 0.01) while PO.1 was found to increase significantly (p less than 0.01). However, no significant changes were noted in breathing pattern. After B FEV1 returned to control values while PO.1, even if significantly reduced (p less than 0.01), did not. Changes in PO.1 were found to be significantly related to changes in FEV1 both during HBPT and B (p less than 0.05). The data suggest that in these patients non-vagal afferences, linked to the abnormalities of thoraco-pulmonary mechanics, could play a major role in changing neural drive to the respiratory muscles.

Adult↗
PubMed1985

Epidemiological aspects of HTLV-III infection in Italy.

An epidemiological survey on the presence of serum antibodies to human T lymphotropic retrovirus III (HTLV-III) is reported. The study was carried out on people living in large as well as small cities in different Italian regions. Serum samples of 21 patients with AIDS, 402 with ARCS, and 920 from individuals at risk for these diseases were analyzed. The percentage of positive sera varied from 81% in AIDS, to 100% -33.3% in ARC according to the different geographical areas and/or the various categories of people with ARC. The percentage of positive sera in individuals at risk for AIDS or ARC varied from 11.9% in homosexuals, to 21% in drug abusers and 23.1% in haemophiliacs. No positive sera were observed among 660 normal individuals, relatives of patients with AIDS or ARC and in 114 patients suffering from immunological or infectious disease and among people at risk living in small cities. Sera were also negative in patients with classical Kaposi's sarcoma or T-cell chronic lymphocytic leukemia. Since none of the 660 unselected normal adults were positive while a significant percentage of people at risk for AIDS showed antibodies to HTLV-III, we may presume that this infection is prevalent in the Italian categories in which AIDS and ARC are most likely to develop.

AIDS-Related Complex↗