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Biomedical subjects

G Gobbi

Publications and source records attributed to G Gobbi.

At least 91 records · Page 5Linked to original sources

Holter monitoring and provocative maneuvers in assessment of unipolar demand pacemaker myopotential inhibition.

Myopotential inhibition was produced by a combination of different provocative maneuvers in 423 (77%) out of 550 consecutive unipolar pacemaker patients. The most useful maneuvers were the hand-to-shoulder press (90% positivity) and the hand-to-hand press (60% positivity). Three groups of 20 patients were then submitted to 24 hours of Holter monitoring. Group A during the provocative maneuvers had shown myopotential inhibition and symptoms of cerebral ischemia. In group B symptomless myopotential inhibition had been induced. Group C had no myopotential inhibition nor symptoms during the tests. Abnormal pacemaker pauses related to myopotential inhibition were recorded during Holter monitoring in 90% of group A and in 80% of group B patients, but only group A patients showed symptoms. Thus in patients who are able to practice provocative isometric maneuvers and who can be selected according to their response, Holter monitoring seems to offer few advantages in discovering myopotential inhibition and related symptoms.

Adolescent↗

Free and total plasma concentrations of carbamazepine and carbamazepine-10,11-epoxide in epileptic patients: diurnal fluctuations and relationship with side effects.

The diurnal fluctuations in free and total plasma levels of carbamazepine (CBZ) and carbamazepine-10,11-epoxide (CBZ-E) and their relationship with intermittent side effects were examined in 10 epileptic patients stabilized on chronic CBZ therapy alone or in combination with phenobarbital (PB). With a t.i.d. or q.i.d. dosing schedule, total plasma levels of CBZ and CBZ-E fluctuated to a similar extent (average 34% and 29%, respectively). The diurnal changes in free levels of both compounds mirrored closely those of the total levels. Free fraction values ranged from 13 to 26% for CBZ and from 24 to 66% for CBZ-E. Owing to the lower protein binding of the metabolite, CBZ-E/CBZ ratios were higher in plasma water (0.49) than in whole plasma (0.22). A good correlation was found between both total and free CBZ levels and dose-related side effects (diplopia, nystagmus). On the other hand, no apparent relationship was found between side effects and either total or free plasma CBZ-E. The correlation with the presence of neurological signs of toxicity for the sum of CBZ + CBZ-E levels was no better than that observed for CBZ levels alone. These data do not support the hypothesis that CBZ-E contributes significantly to the development of dose-related side effects in CBZ-treated patients.

Adult↗

Diurnal fluctuations in free and total plasma concentrations of valproic acid at steady state in epileptic patients.

The diurnal fluctuations in free and total plasma concentrations of valproic acid (VPA) were determined by taking serial blood samples at 2-h intervals in six epileptic patients receiving maintenance therapy with sodium valproate (9.6-24.0 mg/kg in three divided daily doses). Both the free and the total concentrations fluctuated markedly during the period examined (0800-1800 h). The fluctuation of the free drug was about twice as great as that of the total drug (79 +/- 27% versus 47 +/- 21%, p less than 0.01). There was a considerable inter- and intrapatient variability in free VPA fraction. In at least four of six patients the free fraction increased in proportion to the increase in total concentration. These findings are in line with available evidence that the binding of VPA to plasma proteins is saturable within the clinically occurring concentration range. The changing and unpredictable relationship between total and free concentration suggests that VPA therapy can be monitored more rationally by measuring the free drug.

Adolescent↗

Growth hormone release during sleep in growth-retarded children with normal response to pharmacological tests.

Twenty-one prepubertal children of small stature, 10 boys and 11 girls, aged from 4-3 to 12-8 years, were studied. Their height was less than 3rd centile, and during the preceding year all had a growth rate less than 4-5 cm/year. Arginine and L-dopa tests were given, and the release of growth hormone (GH) during monitored sleep was investigated. On the basis of the electroencephalogram and horizontal electro-oculogram, sleep was divided into stages 1-2-3-4 and rapid-eye-movement. All the children had a GH response greater than 8 ng/ml in at least one of the two pharmacological tests, and were therefore accepted as not suffering from GH deficiency. In all 21 children during sleep there was at least one secretory peak with GH greater than 8 ng/ml. Of a total of 46 secretory peaks recorded, 22 (48%) took place during deep, slow sleep (stages 3-4), 10 (22%) during light sleep (stage 2), 10 (22%) during REM sleep, and 4 (8%) during wakening. In 4 patients (19%) no secretory peak was observed during stages 3-4, even though there were peaks at other times. The data (a) show that it is essential to monitor GH throughout the night to ascertain with certainty the presence or absence of physiological secretory peaks of GH; (b) emphasise the rare disagreement between pharmacological and physiological tests; (c) suggest the use of this physiological test for GH secretion in those cases where the insulin test may be hazardous.

Arginine↗