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Biomedical subjects

G Scano

Publications and source records attributed to G Scano.

At least 91 records · Page 5Linked to original sources
PubMed1993

Control of breathing in patients with severe hypothyroidism.

PURPOSE: Hypothyroid patients have been reported to have a blunted ventilatory response to carbon dioxide stimulation. However, previous data did not clarify the localization of abnormalities responsible for that disorder. The present investigation was aimed at evaluating to what extent central (neural) and/or peripheral (muscular) factors are involved in the abnormalities of the ventilatory control system in hypothyroid patients. PATIENTS AND METHODS: We studied 13 patients with severe hypothyroidism before and after 6 to 9 months of replacement therapy; 7 age- and sex-matched normal subjects were also studied as a control. In each subject, we assessed (1) inspiratory muscle strength by measuring maximal inspiratory pressure (MIP), and (2) respiratory control system during a carbon dioxide rebreathing test by measuring minute ventilation (VE), tidal volume (VT), mean inspiratory flow (VT/TI), and electromyographic (EMG) activity of the diaphragm (Edi) and intercostal (Eint) muscles. RESULTS: Compared with the normal control group (Group C), patients exhibited similar MIP, and similar VE and EMG response slopes to carbon dioxide. However, evaluating individual VE response slopes, we were able to identify two subsets of patients: Group A (six patients) with low VE response (less than mean -SD.1.65 of Group C) and Group B (seven patients) with normal VE response. Compared with both Groups B and C, Group A exhibited significantly lower VT/TI, Edi, and Eint response slopes; the difference between Groups B and C was not significant. Six patients (two from Group A and four from Group B) exhibited low MIP values compared with that in Group C. After replacement therapy, (1) VE, VT/TI, and Edi response slopes increased significantly in Group A; and (2) MIP increased, but not significantly in patients with low MIP. CONCLUSIONS: We conclude that: (1) In patients with severe hypothyroidism, the ventilatory control system may be altered at the neural level, as indicated by a blunted chemosensitivity; (2) Impaired respiratory muscle function does not seem to play a major role in the decreased ventilatory response to carbon dioxide stimulation; (3) Replacement therapy appears to normalize the response to hypercapnic stimulation, but not respiratory muscle strength.

Adult↗
PubMed1993

Preventive effects of beclomethasone on histamine-induced changes in breathing pattern in asthma.

Bronchial mucosa inflammation is a hallmark of asthma. Epithelial damage due to inflammatory process may contribute to induce a pattern of rapid and shallow breathing (RSB). Probably due to its effects on inflammatory process, beclomethasone dipropionate (BDP) decreases bronchial hypersensitivity (BH), as assessed in terms of histamine concentration causing a 20 percent FEV1 decrease from saline solution (PC20FEV1); however, no data are available on the effect of BDP on RSB. We studied 32 asymptomatic asthmatic subjects with a severe to moderate levels of BH (PC20FEV1 0.01 to 1.7 mg/ml). After they were randomly assigned to one month of either BDP (2 mg daily, 17 patients) or placebo (15 patients), they inhaled progressively doubling concentrations of histamine phosphate by tidal breathing method. With histamine in seven BDP-treated and in five placebo-treated patients, decrease in FEV1 > or = 20 percent from saline solution was paralleled by a significant decrease in tidal volume (VT), inspiratory time (Ti), and expiratory time (Te), and increase in respiratory frequency (RF). In the remaining patients, histamine failed to change the breathing pattern. In the seven RSB patients, BDP resulted in a smaller VT decrease (p < 0.02) and a smaller RF increase (p < 0.02) with histamine. The five RSB placebo-treated patients were then given one month BDP (2 mg daily): inhaled BDP, but not placebo, resulted both in a significant increase in PC20FEV1 and modulation in histamine-induced changes in breathing pattern. We conclude that high doses of BDP seem to be able to modulate histamine-induced RSB, an effect that might be linked to reversal of airway inflammation.

Adolescent↗
PubMed1993

Effects of intravenous broxaterol on respiratory drive and neuromuscular coupling in COPD patients.

Broxaterol, a new selective beta 2-agonist, has been shown to exert inotropic effects on both fresh and fatigued canine diaphragm. We evaluated the effect of broxaterol on the activation and force output of the respiratory muscles in patients with chronic obstructive pulmonary disease (COPD). We studied 9 patients with moderate to severe COPD. Each patient was infused with saline and Broxaterol (200 micrograms) in saline alternately. We measured lung volumes, maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), breathing pattern, P0.1, respiratory muscle EMG (diaphragm, EMGd, and parasternal, EMGp) and P0.1/EMGd ratio. Measurements were made under control conditions and at 15, 30, 60, and 120 min after each infusion. Broxaterol, but not saline, resulted in a slight but significant increase in vital capacity (VC), forced expiratory volume in one second (FEV1) and MIP, and a decrease in functional residual capacity (FRC). Breathing pattern did not change, while EMG significantly decreased, and P0.1/EMGd significantly increased in 5 of the 9 patients after broxaterol. These data seem to indicate that by partially unloading the respiratory muscles, broxaterol results in decreased muscle activation (EMG). Increase in chest wall neuromuscular coupling (P0.1/EMGd) may also be observed.

Adrenergic beta-Agonists↗
PubMed1993

Control of breathing in patients with neuromuscular diseases.

We reviewed the studies devoted to investigate the control of breathing in patients with neuromuscular diseases. Neural respiratory drive has been assessed in terms of minute ventilation and mouth occlusion pressure (P0.1) in patients with several types of neuromuscular affections (amyotrophic lateral sclerosis, poliomyelitis and post-polio syndrome, Guillain Barré syndrome, muscular dystrophies, inflammatory muscle diseases). More recently we have used electromyographic activity of diaphragm to evaluate neural drive in patients with myasthenia gravis and muscular dystrophies. The results of these studies seem to indicate that patients with myasthenia gravis are not likely to have a decreased respiratory drive, the disorder in neuromuscular transmission being probably the reason for the apparent decrease in diaphragmatic neural activation during hypercapnic stimulation. Increase in neural afferent information from lung and/or rib cage might explain both the increased neural respiratory drive and the faster breathing observed in patients with neuromuscular disease.

Humans↗
PubMed1992

Control of breathing in patients with myasthenia gravis.

Control of breathing has seldom been investigated in patients with myasthenia gravis (MG). We evaluated lung volumes and respiratory muscle strength by measuring maximal inspiratory (MIP) and expiratory (MEP) pressures in 12 patients with moderate generalized (IIb) MG before and after an orally administered therapeutic dose (120 mg) of Mestinon, and in 11 age- and sex-matched normal subjects. Breathing pattern, mouth occlusion pressure (P0.1), and surface electromyographic activity of the diaphragm (EMGd) and intercostal (EMGint) muscles were evaluated during both room-air breathing and hypercapnic rebreathing. Before Mestinon, patients exhibited a slight decrease in VC, and normal TLC and FEV1/VC ratio. Compared with the normal control group, patients also exhibited respiratory muscle weakness (marked decrease in MIP and MEP; p less than 0.001 for both), and more rapid and shallower breathing (RSB): lower tidal volume (VT), inspiratory time (TI), expiratory time (TE), and greater respiratory frequency (f); mean inspiratory flow (VT/TI) and P0.1 were slightly supernormal, whereas both EMGd and EMGint were significantly higher in patients. During hypercapnic rebreathing, ventilation (VE) (p less than 0.001), VT (p less than 0.001), VT/TI, (p less than 0.003), P0.1 (p less than 0.003), and EMGd (p less than 0.001) response slopes to increasing PCO2 were found to be lower, whereas EMGint response slope was normal. At 60 mm Hg of PCO2 in the two groups the difference in terms of breathing pattern, P0.1, and EMGd were similar to that observed during room-air breathing. After Mestinon, VC (p less than 0.005), MIP (p less than 0.02), and MEP (p less than 0.01) significantly increased, whereas spontaneous breathing remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[The effect of antihypertensive therapy on the seasonal variations in arterial pressure in hypertensive patients].

To evaluate the influence of antihypertensive therapy (AHT) on blood pressure (BP) seasonal variations, we have analyzed the systolic and diastolic BP values in 145 hypertensives, 112 males and 33 females, aged 23-65 years, in the 10-year period 1981-1990. All patients received medical treatment and were examined for at least 5-7 consecutive years. The year was divided in 2 (cold and warm months) and 4 periods in relation to mean monthly environmental temperature (10 degrees C, 13 degrees C, 18 degrees C and 23 degrees C). Systolic and diastolic BP was higher in cold months (142/93 vs 137/88 mmHg, p less than 0.05). In cold periods AHT was increased in 11% of patients and decreased in 8%. In the warm periods AHT was decreased in 11% of patients and increased in 6%. The AHT reduction in the warm months was not significantly different in comparison to that of cold months. Vice versa, the AHT increase in cold months was greater than that of warm periods (p less than 0.001). In the 10-year period considered, 18% of patients reduced AHT in the warm period and increased it in the cold period. It was also found a small correlation between diastolic blood pressure and wind, which is, in our country, mostly the mistral. Betablockers, calcium-antagonists and the association betablocker-diuretics showed a seasonal BP variation, while patients treated by diuretic had the same BP both in winter and in summer. A small negative correlation was observed between systolic and diastolic BP and temperature in patients treated by all antihypertensive drugs except the diuretics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Respiratory responses induced by the activation of somatic nociceptive afferents in humans.

To further investigate the role of somatic nociceptive afferents in the neural control of breathing, we studied the respiratory effects of their activation by means of either electrical stimulation or ischemic pain in 14 healthy volunteers. Painful electrical cutaneous stimulation increased respiratory frequency (f), mean inspiratory flow (VT/TI), and rate of rise (XP/TI) of integrated electromyographic activity of diaphragm (IEMGdi). Painful muscular electrical stimulation caused similar but larger changes accompanied by increases in tidal volume (VT), peak XP of IEMGdi, and ventilation (VE); it also entrained respiratory rhythm. Ischemic pain, which was characterized by a progressively increasing intensity, caused augmentation in respiratory activity that displayed an increasing trend: VE, f, VT, XP, VT/TI, and XP/TI increased. In the light of available literature, it seems conceivable to suggest that respiratory responses to painful electrical stimulation are mediated through the activation of cutaneous (A delta) and muscular (group III) fine-myelinated afferents, and responses to ischemic pain are mediated by the activation of both fine myelinated (group III) and unmyelinated (group IV) muscular afferents. The input conveyed by these afferents may constitute an effective stimulus to respiration in humans.

Adult↗
PubMed1991

Control of breathing in patients with chronic pulmonary obstructive disease: response to bamiphylline.

In two groups (A and B) of patients with severe chronic obstructive pulmonary disease (COPD), matched for age and routine pulmonary function testing, we evaluated inspiratory muscle strength (MIP), breathing pattern, mouth occlusion pressure (P0.1), inspiratory neural drive, assessed in terms of electromyographic activity of both diaphragm (EMGd) and intercostal (EMGint) muscles, and P0.1/EMGd ratio, an index of inspiratory neuromuscular coupling. Group A (8 patients) was studied before and after a 7-day period of a new oral xanthine derivative (bamiphylline, 1.2 g daily), and group B (7 patients) was given a placebo. Under control conditions, compared with an age-matched normal control group, groups A and B both exhibited a decrease in MIP, more rapid (increase in respiratory frequency RF) and shallower (decrease in tidal volume; VT) breathing (RSB), a marked increase in both EMGd and EMGint and a lower P0.1/EMGd ratio. With bamiphylline FEV1 and PaO2 significantly increased, while a substantial increase in MIP was found in 5 out of the 8 patients. VT and inspiratory time (Ti) also significantly increased, and RF decreased. Both EMGd and EMGint significantly decreased, whereas P0.1/EMGd exhibited a substantial increase in 5 out of the 8 patients. Conversely, no significant changes were observed in group B during the study period. From these data we conclude that in patients with COPD, clinical manifestations, probably associated with inspiratory muscle overloading (decrease in muscle strength, RSB, increase in respiratory neural drive, and derangement in neuromuscular coupling) may benefit from a short-term treatment with bamiphylline.

Aged↗
PubMed1991

Suppression of ventilatory muscle activity in healthy subjects and COPD patients with negative pressure ventilation.

We evaluated the ability of NPV to suppress EMGd and EMGint in seven patients with severe COPD and five normal subjects. Subjects were studied either without (A) or with mouthpiece and nose clip (B). Electromyographic suppression was assessed comparing EMG activity during NPV with the control activity without a mouthpiece and prior to the initiation of the NPV run. In normal subjects, in A, NPV resulted in a partial suppression of EMGd; in B, prior to NPV, EMGd rose compared with A prior to NPV. In patients, in A, NPV resulted in a suppression of both EMGd and EMGint. In B, prior to NPV, both EMGd and EMGint rose compared with A prior to NPV. Thus, it seems that NPV is able to produce a consistent reduction in inspiratory muscle EMG activity. This variable NPV ability would have to be assessed for better selection criteria for patient candidates in a rehabilitation program.

Adult↗
PubMed1991

[Arterial blood pressure behavior during progressive muscular exercise in subjects with stable arterial hypertension].

To assess the behaviour of blood pressure (BP) during exercise in hypertensive patients (H), 103 males aged 21 to 59 years (mean 43 years) with essential hypertension WHO class I-II were studied. All H, without antihypertensive therapy for at least 15 days, underwent sitting bicycle exercise (10 W/min). BP was measured on the left arm by a standard mercury sphygmomanometer. The fifth Korotkoff phase was taken as the diastolic pressure. Heart rate was measured by electrocardiogram. Subjects were studied at rest in sitting position, during exercise every 3 min and during recovery at 1, 3 and 5 min. As controls we took 100 normotensive (N) males aged 20 to 59 years (mean 39 years). The results were analyzed also by decades. Systolic (S) and diastolic (D) blood pressure were higher in H in comparison with N at rest, in sitting position, (N 119 +/- 10/79 +/- 7 mmHg; H 162 +/- 21/112 +/- 11 mmHg; p less than 0.01), during exercise and recovery. SBP and, to a lesser extent DBP, progressively increased during exercise both in N and in H patients (at peak exercise: N 192 +/- 20/85 +/- 13 mmHg; H 239 +/- 25/121 +/- 13 mmHg, p less than 0.01). The mean increase of SBP during exercise was 77 mmHg in H and 73 mmHg in N (NS). DBP increment was about 6 mmHg in N and 9 mmHg in H (NS). Within the age decades, SBP during exercise was higher in the age group of 50 to 59 in comparison with 20 to 29 in N and H (p less than 0.05) and DBP in the age group of 40 to 49 and 50 to 59 in comparison with 20 to 29 and 30 to 39 (p less than 0.01). The fall of SBP and DBP was greater at 1 min of recovery both in H and N and became progressively smaller thereafter. At a same workload (90 and 120 W) 60% of H had SBP and 85% had DBP higher than BP in N (above 200/104 mmHg--mean + 2 SD--at 90 W and 215/106 mmHg at 120 W). No difference was observed in heart rate at rest and during exercise between N and H. In conclusion, H had SBP and DBP higher at rest, during exercise and recovery in comparison with N. However, a parallel increase of BP was found in the 2 groups during exercise. Ergometric test showed that 60-85% of H had also excessive increase of systolic and diastolic blood pressure during exercise.

Adult↗
PubMed1990

Influence of 4-hydroxynonenal on chemiluminescence production by unstimulated and opsonized zymosan-stimulated human neutrophils.

The lipid peroxidation product 4-hydroxy-2, 3-trans-nonenal (HNE) has a spectrum of biological effects on different cell types depending on the concentrations tested. In particular micromolar HNE concentrations stimulate neutrophil migration and polarization whereas higher doses inhibit. In our experimental conditions, fMet-Leu-Phe (fMLP) increased CL production of both unstimulated and zymosan-stimulated neutrophils, whereas cell stimulation with low HNE concentrations as well as zymosan addition to HNE incubated cells did not enhance light emission. In contrast 10(-4) M HNE reduced CL emission by unstimulated cells nearly to background values, completely depressed CL production by zymosan-stimulated cells and reduced phagocytosis. Cysteine was found to be able to counteract the HNE effect by about 70 per cent. The possibility that this aldehyde could exert its inhibitory effect through the alkylation of NADPH-oxidase SH-groups is postulated. Moreover, our present data on differences observed between fMLP and HNE indicate a different chemotactic mechanism induced by these two classes of compounds and lead to the conclusion that the local functional features of the attracted cells may be different.

Aldehydes↗
PubMed1990

Red-cell enzyme polymorphisms in the Reggio Calabria province (Italy).

Acid phosphatase (ACP1), adenosine deaminase (ADA), esterase D (ESD), glyoxalase 1 (GLO1), phosphogluconate dehydrogenase (PGD) and phosphoglucomutase 1 and 2 (PGM1 and PGM2) polymorphisms have been studied in the Reggio Calabria province (Southern Italy). The ACP1*A allele and ADA, GLO1, PGD and PGM1 systems have frequencies similar to those reported for Sicily and Southern Italy.

Acid Phosphatase↗
PubMed1990

Inspiratory muscle strength and respiratory drive in patients with rheumatoid arthritis.

In 15 patients with rheumatoid arthritis (RA) and in 12 age- and sex-matched normal subjects, we evaluated inspiratory muscle strength and respiratory control system. Inspiratory muscle strength was assessed by measuring maximal inspiratory pressure (MIP). Respiratory drive was assessed by evaluating surface electromyographic activity of the diaphragm (EMGd) during both room-air breathing and hypercapnic rebreathing. Compared to the predicted value (mean +/- 1.65 SD), MIP was significantly reduced in nine patients (60%). All told, we noticed a significant inverse relationship in the patients between MIP and duration of steroid therapy (p less than 0.01). During room-air breathing, both EMGd and mouth occlusion pressure (P0.1), expressed both in actual values and as percentage of MIP, were significantly greater in patients than in the normal control group (p less than 0.001 for both). Both EMGd and P0.1 (%MIP) response slopes to CO2 were significantly greater in patients than in the normal control group (p less than 0.01 and p less than 0.001, respectively) and significantly related to the functional stage of disease. During quiet breathing and for a PETCO2 of 60 mm Hg, both EMGd (p less than 0.01 and p less than 0.05, respectively) and P0.1 (%MIP) (p less than 0.01 and p = 0.001, respectively) were inversely related to MIP. These results indicate that RA patients may exhibit inspiratory muscle weakness and increased respiratory drive. Steroid myopathy and rheumatoid myositis could explain the reduction in MIP, whereas neural afferents arising from respiratory muscle, lung, or joint receptors could be involved in the observed increase in neural drive.

Arthritis, Rheumatoid↗
PubMed1990

Changes in ventilatory muscle function with negative pressure ventilation in patients with severe COPD.

Patients with severe COPD may be in a state of ventilatory muscle (VM) fatigue. In these patients, rapid and shallow breathing has been hypothesized to be a compensatory mechanism that prevents more severe fatigue from taking place. To test these hypotheses, we studied the effects of VM resting in a group of patients with severe COPD. Eleven clinically stable patients with COPD and chronic hypercapnia were studied. Six of them (group A) had a seven-day period of negative pressure-assisted ventilation (NPV), and five (group B) with similar functional characteristics served as a control group. Compared with a normal age-matched control group, both A and B groups exhibited significantly lower tidal volume (VT), inspiratory time (TI), total time of the respiratory cycle (Ttot) and Ti/Ttot ratio, decrease in muscle strength, and greater electromyographic activity of diaphragm (EMGd) and parasternal muscles, but similar ventilation and VT/TI. After the study period, group A exhibited significant increase in VT, Ti, and TI/Ttot (p less than 0.05), and decrease in PaCO2 (p less than 0.05), EMGd, and EMGint (p less than 0.05 for both), and a slight but significant increase in maximal inspiratory pressure (MIP) (p less than 0.05). These data suggest that NPV rests VM, increases their strength, and reduces hypercapnia in patients with severe COPD.

Aged↗
PubMed1990

Neural respiratory drive and neuromuscular coupling in patients with chronic obstructive pulmonary disease (COPD).

In 15 spontaneously breathing patients with chronic obstructive pulmonary disease (COPD) divided into two groups, one with normocapnia (A) and one with chronic hypercapnia (B), we evaluated the maximal voluntary inspiratory muscle strength (MIP), the pattern of breathing, the mouth occlusion pressure (Po.1), the neural respiratory drive (NRD), assessed by surface electromyographic (EMG) activity of the diaphragm (EMGd) and EMG activity of intercostal muscles (EMGint), and the chest wall neuromuscular coupling, assessed in terms of Po.1/EMGd ratio. Compared with an age-matched normal control group, both A and B groups exhibited lower MIP, significantly greater EMGd and EMGint, and lower Po.1/EMGd ratio. However, a similar pattern, along with a rapid and shallow breathing, differentiated group B from group A. In group B we found a significant direct relationship between Po.1/EMGd ratio and MIP, and an inverse relationship between PaCO2 and Po.1/EMGd ratio. These data seem to indicate the following: (1) EMG is a more precise method than Po.1 in assessing the magnitude of the NRD; (2) NRD is increased in these patients; and (3) clinical manifestations probably associated with inspiratory muscle fatigue (marked decrease in muscle strength, rapid and shallow breathing, and alveolar hypoventilation) may be accompanied by a greater NRD and a more marked derangement in chest wall neuromuscular coupling in COPD.

Aged↗
PubMed1989

Control of breathing in patients with short-term primary hypothyroidism.

In 8 patients (3 men and 5 women) with short-term primary hypothyroidism before and during replacement therapy, and in an age-matched control group (9 men and 7 women), we assessed maximal inspiratory muscle force (Pimax) and the ventilatory control system at neural (EMG), muscular (P0.1), and ventilatory (VE and Vt/Ti) levels. While hypothyroid, patients exhibited a significantly lower Pimax. During a CO2 rebreathing test, hypothyroid patients exhibited similar diaphragmatic electromyographic (EMGd) and ventilatory (VE) response slopes to increasing end-tidal CO2 tension (delta EMGd/delta Pet CO2 and delta VE/delta PetCO2), but significantly less delta P0.1/delta PetCO2 (p less than 0.05) and delta(Vt/Ti)/delta PetCO2 (p less than 0.05) response slopes. During replacement therapy with L-triiodothyronine (L-T3), Pimax (p less than 0.05), delta P0.1/delta PetCO2, and delta(Vt/Ti)/delta PetCO2 response slopes were found to be significantly increased (p less than 0.05 for both) while neither EMGd nor VE response changed significantly. We concluded that short-term hypothyroidism does not seem to be associated with blunted neural inspiratory output (EMGd), the respiratory control system seems to be affected mostly at a peripheral (muscular) level, and L-T3 increases both force (P0.1 and Pimax) and velocity (Vt/Ti) of inspiratory muscle contraction.

Adult↗