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Biomedical subjects

S Nava

Publications and source records attributed to S Nava.

At least 127 records · Page 7Linked to original sources
PubMed1990

Aminophylline and human diaphragm strength in vivo.

The transdiaphragmatic pressure (Pdi) twitch response to single shocks from supramaximal bilateral phrenic nerve stimulation was studied before and after acute intravenous infusions of aminophylline [14.9 +/- 3.1 (SD) micrograms/ml] in nine normal subjects. Stimulation was performed with subjects in the sitting position against an occluded airway from end expiration. Baseline gastric pressure and abdominal and rib cage configuration were kept constant. There was no significant difference in peak twitch Pdi from the relaxed diaphragm between control (38.8 +/- 3.3 cmH2O) and aminophylline (40.2 +/- 5.2 cmH2O) experiments. Other twitch characteristics including contraction time, half-relaxation time, and maximum relaxation rate were also unchanged. The Pdi-twitch amplitude at different levels of voluntary Pdi was measured with the twitch occlusion technique, and this relationship was found to be similar under control conditions and after aminophylline. With this technique, maximum Pdi (Pdimax) was calculated as the Pdi at which stimulation would result in no Pdi twitch because all motor units are already maximally activated. No significant change was found in mean calculated Pdimax between control (146.9 +/- 27.0 cmH2O) and aminophylline (149.2 +/- 26.0 cmH2O) experiments. We conclude from this study that the acute administration of aminophylline at therapeutic concentrations does not significantly affect contractility or maximum strength of the normal human diaphragm in vivo.

Adult↗
PubMed1990

Diaphragmatic rest during negative pressure ventilation by pneumowrap. Assessment in normal and COPD patients.

In the present study, we assessed the occurrence of respiratory muscle rest during long lasting INPV runs using a pneumowrap ventilator at different pressure levels. We measured two indices of diaphragmatic activity: transdiaphragmatic pressure and the electrical activity of the diaphragm. Five healthy volunteers and six COPD patients were studied during spontaneous breathing and during 30-minute runs of INPV at a pressure of -2, -15 and -30 cmH2O. Ventilation, rib cage and abdomen motion were measured by inductive plethysmography; Pdi was obtained as the difference between gastric and esophageal pressures; Edi was recorded with surface electrodes. About 10 minutes of INPV (adaptation phase) were needed to obtain stable values in all the variables recorded. Ventilation increased in both groups up to threefold by increasing the negative pressure applied, this being due to changes in tidal volume. Changes in Pga swings mainly accounted for the reduction in Pdi that became negative during the run at -30 cmH2O. In both groups, Edi, after adaptation, showed no change during INPV at -2 cmH2O but a progressive reduction from control, during INPV at -15 and -30 cmH2O. We conclude that INPV by a pneumowrap ventilator can induce partial respiratory muscle rest in normal subjects and COPD patients.

Adult↗
PubMed1990

Endometrial patterns during danazol and buserelin therapy for endometriosis: comparative structural and ultrastructural study.

We studied endometrial structure and ultrastructure in serial biopsy specimens from patients with endometriosis treated with danazol (N = 19) or intranasal buserelin (N = 13) for 6 months. Biopsies were performed before and at 3 and 6 months of treatment. The specimens were studied by light, scanning, and transmission electron microscopy. Six morphometric indices were evaluated. Danazol produced a progestational effect on endometrial glands and stroma associated with marked hypotrophy of the mucosa, and buserelin treatment resulted in weakly proliferative or inactive mucosa. Both drugs induced noncyclicity and hypotrophy of endometrium although with different mechanisms of action, and it is suggested that they may have similar effects on ectopic endometrium. Because the atrophic effect of danazol appeared earlier than that of buserelin, the former could be recommended for short-term therapy.

Adult↗
PubMed1990

[Interventricular muscular defect in the atrioventricular canal].

The muscular ventricular septal defect associated with the atrioventricular canal is a malformation which has not yet been extensively studied. Between June 1982 and December 1989, 151 patients with atrioventricular canal underwent echocardiography and angiocardiography in our Department. Of these 95 (62.9%) had a complete form and 56 (37.1%) a partial. Among the 151 patients, 81 (53.6%) presented Down syndrome. We found 5 muscular ventricular septal defects in 4 patients; in 3 cases there was a single defect and in one case two defects. These defects were midmuscular in all patients and one patient also presented an apical defect. All 4 patients with muscular ventricular septal defect presented a complete atrioventricular canal and aortic coarctation; 3 out of 4 patients had a hypoplastic left ventricle with absence of Down syndrome. The muscular ventricular septal defect is a malformation which is rarely associated with atrioventricular canal (4/151 = 2.6%). In our experience, it was always associated with a complete form with aortic coarctation and was very rare in Down syndrome patients (1/81 = 1.2%). These findings may represent a peculiar association of anomalies which may be caused by fetal hemodynamic mechanisms.

Abnormalities, Multiple↗
PubMed1990

Short term effect of intermittent negative pressure ventilation in COPD patients with respiratory failure.

Ten patients with stable chronic obstructive pulmonary disease (COPD) and hypercapnic respiratory failure were randomly submitted to intermittent negative pressure ventilation (INPV) 6 h per day for 5 consecutive days by either a cuirass or pneumo wrap ventilator. The effects were assessed by measurements of spirometry, blood gases, maximal inspiratory (MIP) and expiratory (MEP) pressures, 12 minutes walking distance test (12 mwd), sensation of dyspnoea by a visual analogue scale (VAS) and diaphragmatic electromyographic activity (Edi). Edi was recorded during INPV sessions in only 7 patients. The same measurements apart from Edi were also performed in 8 matched control patients randomly submitted to conventional physiotherapy. During INPV, Edi activity was reduced, at least temporarily down to 50% of baseline values. Comparison of baseline with post INPV values showed no changes in thoracic gas volume (TGV), forced expiratory volume in one second (FEV1), FEV1/forced vital capacity (FVC), arterial oxygen partial pressure (Pao2) and MEP; significant improvements were seen in MIP, vital capacity (VC), VAS, and 12 mwd only in patients submitted to INPV. A significant improvement in PaCO2 was observed in both groups of patients. We conclude that INPV may be effective in improving the functional reserve of the inspiratory muscles in selected COPD patients with hypercapnic respiratory failure and signs of inspiratory muscle dysfunction.

Breathing Exercises↗
PubMed1989

Cardiovascular failure and apnea in shock.

A model of shock was developed in anesthetized dogs by limiting venous return with a balloon inflated in the right atrium. The change in ventilation (VE) in response to a sustained decrease in arterial pressure (Pa) to 50-60 Torr was studied by recording transdiaphragmatic pressure (Pdi) and diaphragm (Edi) and parasternal intercostal (Eic) electrical activity. Four dogs died of cardiac arrest after 20-60 min. In 11 dogs, VE, after an initial increase, decreased progressively until apnea occurred after 103 +/- 24 min, after 60% reductions in breathing frequency, Pdi, and Eic and a 30% fall in Edi. No decrease in diaphragm contractility was found in response to artificial phrenic nerve stimulation. The cardiocirculatory function deteriorated during shock until it became irreversible at apneic time. No recovery from apnea occurred without a recovery of Pa. We conclude that the fall in VE and ensuing apnea in this model resulted from a decrease in central respiratory neural output associated with a progressive deterioration of the cardiocirculatory function.

Animals↗
PubMed1988

Multiple and complex effects of buspirone on central dopaminergic system.

The effects of the anxiolytic drug buspirone and its metabolite 1-PP on the dopaminergic system were investigated. A single buspirone administration was found to decrease DA levels and increase its metabolite DOPAC in striatal samples. The levels of the other DA metabolite, 3MT, were unaffected; however its formation rate after inhibition of its metabolism, was found to be increased by buspirone. 1-PP did not affect either DOPAC or 3MT levels and formation. Striatal microdialysis showed that buspirone enhances DA release. In vivo voltammetry indicates that the increase of DA metabolism is identical in the two sampled dopaminergic areas, striatum and nucleus accumbens. On the basis of the results obtained ex vivo and in vivo the multiple effect of buspirone on dopaminergic system is discussed.

Animals↗
PubMed1987

[Concomitant therapy with cisplatin and radiotherapy in locally advanced tumors of the cervico-facial area].

Nineteen patients with locally advanced head and neck cancer were treated from November 1983 to January 1986 with standard loco-regional Radiotherapy: 2 Gy for 5 days/week up to a total dose of 70 Gy and simultaneous Cisplatinum 20 mg/m2 weekly. All patients achieved a response: 10 (52%) obtained a complete remission (CR) and 9 (48%) a partial remission (PR). Four of 9 patients in PR after chemoradiotherapy were disease-free after radical resection of the residual masses, while another patient was completely cured after second-line chemotherapy. The overall CR was then 79% (15/19). The results were analyzed according to the nodal status and showed that: 92% (11/12) of patients with initial nodal involvement (N1-2) achieved a CR and 75% of them were disease-free after a median follow-up of 23+ months, while only 57% (4/7) of patients with advanced nodal involvement (N3) obtained a CR (p greater than 0.05; NS) and 28% (2/7) of them were alive without evidence of disease (p less than 0.05) after 4+ and 30+ months. Toxicity was moderate: nausea and vomiting (grade 2-3) occurred in about 50% of patients, mucosal toxicity (grade 1-2) in 58%. Myelosuppression was negligible. No patient developed renal failure. Weekly cisplatinum administration during radiotherapy deserves further study especially in the management of patients with advanced primary tumor and minimal lymph node involvement.

Adult↗
PubMed1986

[Right cardiac echinococcosis with coronary compression. Description of a clinical case].

An outstanding case of cardiac echinococcosis is described. Clinical symptomatology was characterized by typical nitroglycerin-responsive crisis of angina pectoris associated to an electrocardiographic pattern of negative T wave on anterolateral and inferior leads. The diagnosis was suspected on the basis of thoracic computerized tomography and coronary arteriography. The anatomical localization was mainly pericardial but the right ventricle was involved too. Left anterior descending artery was dislocated and squeezed.

Adult↗
PubMed1983

[Complete sub-His AV block caused by carotid sinus massage. Possible direct vagal effect on the His-Purkinje system].

A 64 year old male patient, with frequent syncopes, underwent an electro-physiologic study. A complete left bundle branch block and a first degree His-Purkinje system atrioventricular block (AH = 100 msec, HV = 60 msec) were present in basal condition. Left carotid sinus massage caused extreme sinus bradycardia (with PP intervals as long as 3000 msec), without AH and HV interval changes. Right carotid sinus massage caused a His-Purkinje atrioventricular block. Ventricular asystole of 4800 msec occurred while the sinus cycle varied between 1440 and 590 msec. Since His-Purkinje atrioventricular block is induced by the right carotid sinus massage with PP intervals even shorter than the basal cycles and since the block was not reproduced at PP intervals longer than 1440 msecs, a direct vagal effect on the His-Purkinje system may be suggested, rather than a bradycardia dependent phase 4 block.

Bradycardia↗