24-Hour Heart Rate Variability in Patients with Vasovagal Syncope

Since alterations in the autonomic nervous system are thought to play a major role in the pathogenesis of vasovagal syncope, we characterized the chronic autonomic profile of 44 patients with syncope and 20 healthy subjects by means of heart rate variability using 24-hour Holter recordings (time- and frequency-domain indexes), and evaluated whether the different types of responses to tilting (vasodepressive versus cardioinhibitory) could be associated with different cardiac autonomic patterns. Twenty-three patients exhibited a positive response to tilting, which was vasodepressive in 11 patients and cardioinhibitory in 12 patients. All vasodepressive patients had a standard deviation of the averages of NN (SDANN) intervals in all 5-minute segments lower than 100 ms. Patients with vasodepressive syncope also had significantly lower values of RMSSD (the 24-hour square root of the mean of the sum of the squares of differences between adjacent normal RR intervals) than those with cardioinhibitory response, and lacked the day-night rhythm of the low frequency/high frequency ratio. However, only SDANN values correctly identified patients with vasodepressive response to tilting. We conclude that (1) the population of patients with vasovagal syncope is heterogeneous, (2) patients with vasodepressive syncope have a peculiar chronic autonomic profile as assessed by 24-hour heart rate variability analysis, and (3) the evaluation of the autonomic profile in 24-hour Holter recordings could be of value in the diagnosis of patients with syncope.     

Postnatal development of intestinal endocrine cell populations in the water buffalo

The frequency and distribution of 11 endocrine cell populations were studied in the intestine of differently aged buffalo, grouped on the basis of diet: 2-d-olds (suckling), 5-mo-olds (weaning) and 5-y-olds (ruminant adult diet). The endocrine cell populations were identified immunocytochemically using antisera against 5-hydroxytryptamine (5-HT), somatostatin, gastrin, cholecystokinin (CCK), COOH-terminal octapeptide of gastrin/CCK, neurotensin, motilin, gastric inhibitory polypeptide (GIP), secretin, glucagon/glicentin (GLU/GLI) and polypeptide YY (PYY). In adult buffalos the regional distribution of endocrine cells is similar to that of other adult ruminants. During postnatal development, these cell types showed the following changes in their frequency and distribution: (1) 5-HT, neurotensin and gastrin/CCK immunoreactive cells (i.c.) showed a decrease in frequency with age; (2) somatostatin i.c. frequency remained stable with age; (3) motilin, GIP, secretin and CCK i.c. showed a slight increase in frequency with age; (4) GLU/GLI and PYY i.c. decreased in frequency with age in the small intestine, caecum and proximal colon and an increase in frequency in the rectum. It was hypothesised that the endocrine cell types, whose presence and localisation is substantially stable in all examined ages, probably contain substances that are strictly necessary for intestinal function. In contrast the hormones contained in the cell populations that decreased with age, are probably involved in physiological needs during the milk and weaning diet or play a role in intestinal growth.     

Oral Loading with Propafenone: A Placebo-Controlled Study in Elderly and Nonelderly Patients with Recent Onset Atrial Fibrillation

The efficacy and safety of propafenone as an oral loading dose (600-mg single oral dose) in converting recent-onset atrial fibrillation (≤ 7 days duration) to sinus rhythm were evaluated in a single-blind, placebo-controlled study according to patients' age. Overall, 240 hospitalized patients, NYHA Class ≤ 2 without signs or symptoms of heart failure were enrolled: among patients aged ≤ 60 years, 55 were allocated to propafenone treatment and 59 to placebo, respectively, and among patients aged > 60 years, 64 were allocated to propafenone treatment and 62 to placebo, respectively. Results: In each age group, the likelihood of conversion to sinus rhythm was significantly greater after propafenone compared with plocebo at 3 and 8 hours. For patients aged ≤ 60 years, corresponding odd ratios were 3.78 (95% CI = 1.80–7.92, P = 0.04) at 3 hours and 4.74 (95% CI = 2.12–10.54, P = 0.02) at 8 hours; for patients aged > 60 years odd ratios were 5.03 (95% CI = 2.08–12.12, P = 0.02) at 3 hours and 6.75 (95% CI = 3.28–73.86, P = 0.01) at 8 hours, respectively. Logistic regression analysis showed that conversion to sinus rhythm within 3 hours was predicted by age ≤ 60 years (P = 0.0064) and by propafenone treatment (P < 0.0001), and conversion to sinus rhythm within 8 hours was predicted by age ≤ 60 years (P = 0.0467) and by propafenone treatment (P < 0.0001). The occurrence of adverse effects was observed in 14%-16% of propafenone treated patients and in 8% of placebo treated patients without significant differences according to age. In conclusion, in patients with recent-onset atrial fibrillation without signs of heart failure, propafenone as a single oral loading dose is effective. It is also effective in selected elderly subjects with a favorable safety profile. Moreover, spontaneous conversion to sinus rhythm appears to occur less frequently in elderly patients.     

Multigenetic lesions in infant acute leukaemias: correlations with ALL-1 gene status

The large majority of childhood B-precursor cell acute lymphoblastic leukaemia cases present IgH and TCRδ gene rearrangements. These rearrangements have been widely used as specific markers for monitoring minimal residual disease. However, their prognostic value still remains unclear. In order to determine whether IgH and TCRδ gene rearrangements have any influence on relapse and event-free survival (EFS), we analysed the clinical impact of these genetic characteristics in 51 B-precursor acute lymphoblastic leukaemia patients. 46/51 patients (90.2%) showed IgH gene rearrangements by Southern blot and/or polymerase chain reaction (PCR) analysis. No statistically significant associations were found between IgH gene rearrangement pattern and age, sex, WBC count, immunophenotype, risk factor, relapse or EFS. 27/41 patients (66%) showed Vδ₂Dδ₃ recombination by Southern blot and/or PCR analysis. At a median follow-up of 53 months the estimated 5-year EFS probability was 78 ± 3% for the whole group. The EFS probability among patients with a Vδ₂Dδ₃ recombination pattern in the TCRδ locus was 90 ± 3%, whereas for patients without Vδ₂Dδ₃ recombination was 39 ± 13% ( P  < 0.005).
IgH rearrangement patterns do not appear to influence relapse or EFS probability. However, TCRδ gene rearrangement patterns have a relevant impact on the relapse rate and the EFS probability. Patients with Vδ₂Dδ₃ recombination have better clinical outcome than patients without this recombination, independent of any other prognostic factors.     

REDUCTION OF PLASMA TRIIODOTHYRONINE (T3) INDUCED BY PROPRANOLOL

The effect of propranolol on plasma triiodothyronine (T3), thyroxine (T4) and triiodothyronine uptake by Sephadex G-25 (RT3U%) was studied in fourteen thyrotoxic patients and eight normal volunteers. 40 mg of propranolol as a single oral dose caused significant reduction in total serum T3 which began 60 min after administration. No significant changes were observed in T4 and RT3U% values. Plasma T3 levels remained suppressed during a 5 day course of treatment with propranolol. These results suggest that propranolol has a direct effect on peripheral metabolism of T3 rather than on thyroid hormone secretion.     

Supernormal Conduction in the Left Bundle Branch

Supernormal Conduction. This report describes a patient with tachycardia-dependent left bundle branch block (LBBB) and atrial extrasystoles, some of which were followed by an unexpectedly narrow QRS complex. His-bundle recordings and premature atrial stimulation were performed to analyze the mechanism underlying the normalized intraventricular conduction of some of the early atrial impulses. The results suggested the presence of supernormal conduction in the left bundle branch (LBB), because(1) the HV interval was identical in LBBB complexes and in early narrow QRS complexes; (2) during single lest stimulation using different paced atrial cycle lengths, there was a well-defined range of H₁, H₂, intervals resulting in normalization of intraventricular conduction; and (3) atrial pacing with a cycle length of 500 msec resulted in alternation between wide and narrow QRS complexes. These findings rule out alternative mechanisms that could explain the unexpectedly normal intraventricular conduction of early impulses.