Circadian variation of short-lasting asymptomatic paroxysmal supraventricular tachycardia

This study determines the circadian variation of transient asymptomatic paroxysmal supraventricular tachycardia (PSVT). A total of 416 asymptomatic PSVT episodes (> or = 10 consecutive supraventricular beats) recorded in 62 patients were obtained from Holter monitoring. The incidence of the onset of PSVT was counted at the 1-hour interval. The duration (beats) and rate (beats/min) of PSVT and the preceding heart rate were also evaluated. The circadian variations of the onset, duration, and rate of PSVT were analyzed by the single cosinor method. The incidence of the onset of PSVT showed a significant circadian variation (P = .001); with high incidence in the daytime and low at nighttime. The rate and duration of PSVT also showed significant circadian variation (P = .02), faster and longer in daytime and slower and shorter at night, respectively. The rate (r = .45, P < .001) and duration (r = .22, P < .001) of PSVT correlated significantly with the preceding heart rate. Our findings suggest that the onset and persistence of short-lasting asymptomatic PSVT exhibit a circadian pattern and that autonomic tone might play an important role in the genesis of this form of PSVT.

Automated, simplified GC/MS data processing system for organic acidemia screening and its application

Gas chromatography mass spectrometry (GC/MS) is widely used in diagnosis of organic acidemias. However, GC/MS has not yet become a routine laboratory test, because of the complexity in interpretation of GC/MS data. We developed a personal computer-based system of automated metabolic profiling and disease detection for the screening of organic acidemias by GC/MS. The data were processed after the GC/MS analysis of urinary organic acids. In this system, 130 kinds of metabolites and 25 disorders of organic acids were enrolled for the search and detection, respectively. Metabolites were identified with methylene unit values (MU). target ions (Q- and C-ions) and their intensity ratios, and semiquantified by peak relative area (%) of the Q-ions to that of an internal standard. Metabolites whose values exceeded the cutoff of the control table were flagged as abnormal. The diseases or pathological condition were automatically evaluated by combination of the abnormal compounds. In this system, index metabolites were categorized into three groups. "AND, "OR" and "NO". The groups, "AND" and "OR" comprised essential and optional compounds, respectively, for the specific diagnosis. The third group, "NO", included compounds which must be absent to reach a diagnosis. We compiled data of MU values and mass spectrum of 130 kinds of index metabolites, and tested the usefulness of this system by analysis of 74 patients with 19 kinds of diseases. In all cases, at least a correct diagnosis could be found among the disease names outputted. We have successfully applied this to a pilot neonatal screening by GC/MS in our regional area, and acylglycine analysis by the stable isotope dilution method with tert-butyldimethylsilyl derivatization. With our system, many people can attend for screening programs using GC/MS.

Gas chromatography-mass spectrometry with tert.-butyldimethylsilyl derivation: use of the simplified sample preparations and the automated data system to screen for organic acidemias

A simplified, sensitive screening method for organic acidemias by gas chromatography-mass spectrometry using urease/direct preparations and tert.-butyldimethylsilylation (TBDMS) instead of trimethylsilylation (TMS) is described. We compiled GC-MS data on TBDMS derivatives, including methylene unit values, and quantifying and confirming ions, for use in the automated data system we developed. Quantification using [M-57]+ ions by mass chromatography was more sensitive, and the coefficient variation was smaller, compared with TMS derivatives. We confirmed the usefulness of this system, analyzing urine specimens from 53 patients with 15 different disorders.

Vagal modulation of ventricular tachyarrhythmias induced by left ansae subclaviae stimulation in rabbits

Previous evidence has shown that vagal nerve activity modulates ventricular arrhythmias in patients and in animal models. However, the effects of direct vagus nerve stimulation on ventricular tachyarrhythmias brought by direct sympathetic nerve stimulation have not been elucidated. In the present study, the effects of electrical stimulation of the left cervical vagus nerve on ventricular tachycardia (VT) which was induced by electrical stimulation of the left ansae subclaviae (LAS) in rabbits were assessed. Monophasic action potentials (MAPs) of the left ventricular endocardium were recorded simultaneously with surface ECG. In 27 rabbits tested, the stimulation of LAS induced VT in 19 rabbits. Polymorphic VT (PVT) was induced in 14 rabbits (PVT group), whereas monomorphic VT (MVT) was induced in 5 rabbits (MVT group). Vagus nerve stimulation during the sympathetically-induced PVT led to a restoration of sinus rhythm in 10 of 14 rabbits, while that during the sympathetically-induced MVT did not restore sinus rhythm in any of the 5 rabbits. Vagus nerve stimulation during the stimulation of LAS, which was of subthreshold intensity for the induction in VT, did not result in an induction of PVT in any of the 14 rabbits in the PVT group, while it induced slow MVT in 3 of 5 rabbits in the MVT group. These results indicate that vagus nerve stimulation preferentially exerts protective antiarrhythmic effects against PVT induced by sympathetic neural stimulation in this model, while it occasionally induces slow MVT under conditions in which sympathetic nerve activity in potentially elevated.

Congenital hypopituitarism with hypoplasia of the anterior pituitary gland and a normal posterior pituitary lobe

We report a female infant with congenital hypopituitarism. All anterior pituitary hormones were deficient, and the anterior pituitary gland was undetectable on magnetic resonance images. Antidiuretic hormone secretion was appropriate, and the posterior lobe was localized at the end of the stalk, in the sella. These observations suggest that the posterior pituitary gland may develop independently of the anterior lobe.

Cardiac atrial natriuretic peptide in monocrotaline-induced pulmonary hypertensive rats

To determine the time course and potential triggers for synthesis of atrial natriuretic peptide (ANP) in right ventricle during the development of right ventricular hypertrophy (RVH), we measured mean right atrial pressure, right ventricular systolic pressure (RVSP), immunoreactive ANP (iANP) concentrations in plasma, and cardiac iANP concentrations and contents of monocrotaline (MCT)-induced pulmonary hypertensive rats treated with a subcutaneous injection of MCT (40 mg/kg). Following the development of RVH and pulmonary hypertension, iANP concentrations in plasma and iANP concentrations and contents in ventricular tissues increased with time. At the third week after treatment, iANP concentrations in MCT rats increased 6-fold in plasma, 57-fold in the right ventricular free wall, 20-fold in the ventricular septum and 10-fold in the left ventricular free wall compared with those in controls. At the third week, iANP contents of total ventricular tissues in MCT and control rats were 29% and 0.8%, respectively, of the corresponding atrial contents. The iANP concentrations and contents of right ventricular free walls in MCT rats were greater than those of any other parts of ventricular tissues. The iANP concentrations in right ventricular free walls were very closely related to RVSP (r = 0.93, P < 0.001). In MCT rats, iANP concentrations in right atrial tissues decreased with time. This study shows that ventricular ANP contributes to the amount of ANP stored within the heart in MCT rats and that pressure overload may be one of the triggers for ANP synthesis in the right ventricle.

Ectopic posterior lobe of the pituitary gland and intractable nocturnal enuresis in a case with pituitary dwarfism

An 11 5/12-year-old girl with pituitary dwarfism had intractable nocturnal enuresis. Magnetic resonance imaging revealed pituitary stalk transection and the formation of an ectopic posterior lobe. The results of responses to dehydration, infusion of hyperosmolar NaCl solution, and 1-desamino-8-D-arginine vasopressin showed that the nocturnal enuresis in the present case was due to a partial vasopressin deficiency. We suggest that the ectopic posterior lobe is one cause of nocturnal enuresis.

[Parvovirus-induced aplastic crisis in a child with hereditary spherocytosis: studies on the mechanisms of hemopoietic suppression]

A 4 4/12-year-old girl with hereditary spherocytosis (HS) who presented with an aplastic crisis during a human parvovirus (HPV) B19 infection is reported. IgM and IgG antibodies to the HPVB19 and HPV19 DNA were detected. Each of Leu 7+, Leu 11+ and HLA-DR+ cells increased. OKT4/OKT8 ratio decreased to 0.71. In order to investigate the mechanism of aplastic crisis, we used an in vitro culture technique for erythroid and granulocyte-macrophage progenitor cells (BFU-E, CFU-E and CFU-C). The patient's HPV19 DNA-containing aplastic phase serum inhibited the formation of BFU-E, CFU-E and CFU-C. After removal of the adherent cells from the aplastic phase bone marrow, the numbers of BFU-E significantly increased. These results suggest that aplastic crisis of the patient with HS was caused by HPVB19, and that monocytes-macrophages and NK cells played an important role in the pathogenesis of aplastic crisis.

Plasma atrial natriuretic polypeptide concentration in healthy children from birth to adolescence

We measured plasma atrial natriuretic polypeptide concentrations in the umbilical artery and vein, and peripheral veins of healthy children from birth to adolescence to establish the normal range. The plasma atrial natriuretic polypeptide concentration in the umbilical artery (mean +/- SD, 51.0 +/- 21.4 fmol/ml) was significantly higher than that in the umbilical vein (18.1 +/- 13.5 fmol/ml) in neonates after vaginal delivery. Also neonates aged 5 days or less had a significantly high concentration in the peripheral vein (60.7 +/- 29.4 fmol/ml). There was no significant difference in atrial natriuretic polypeptide concentrations in the peripheral veins between older children and adults. The concentrations in children aged more than 5 days and adults aged 20-34 years were 14.4 +/- 7.4 fmol/ml and 10.0 +/- 4.8 fmol/ml, respectively. However, the atrial natriuretic polypeptide concentration in the umbilical artery was not increased in three neonates delivered by caesarean section although they had a high concentration in the peripheral vein 24 hours after birth.