Spatiotemporal changes of slow wave activities before and after 14 Hz/12 Hz sleep spindles during stage 2 sleep.

The present study examined the spatiotemporal changes of slow wave (delta and theta bands) activities before and after 14 Hz/12 Hz sleep spindles during stage 2 sleep, using topographic mapping of electroencephalogram (EEG) power. Both types of sleep spindles appeared after slow wave activities of background EEG decreased. Moreover, the appearance of sleep spindles provided increasing EEG slow wave activities in the subsequent period. Further, the present results showed that an appearance of 14 Hz sleep spindle facilitated slow wave activities at the centro-parietal areas, while an appearance of 12 Hz sleep spindle facilitated slow wave activities at the fronto-central areas. These results suggest that sleep spindles provide cortical de-arousal, and serve to maintain sleep.

The vanishing point of the mismatch negativity at sleep onset.

OBJECTIVE: To determine when the mismatch negativity (MMN) disappears at sleep onset, event-related potentials (ERPs) were recorded continuously from wakefulness to sleep. METHODS: Ten healthy young students were told to fall asleep ignoring the tones presented through a loudspeaker above their head. Standard (1000 Hz, P=0.90), high deviant (1200 Hz, P=0.05), and low deviant (1050 Hz, P=0.05) tones were presented in a quasirandom order with a fixed stimulus onset asynchrony of 500 ms. ERP waveforms were obtained separately for 5 successive stages characterized by typical electroencephalographic (EEG) patterns of the sleep onset period. The EEG staging was made manually with very short (5 s) scoring epochs. RESULTS: The MMN appeared in wakefulness and in the early phase of stage 1 sleep (EEG stage II) but disappeared when low-voltage theta waves emerged after alpha flattening (EEG stage III). Instead, P240 and N360 developed particularly for high deviant tones. CONCLUSIONS: Concurrently with the disappearance of alpha waves, the automatic change detection system in wakefulness seems to stop operating and a different sleep-specific system becomes dominant.

Tempo of background sound and performance speed.

24 undergraduates performed a self-paced line tracing task. Fast music accelerated performance compared with slow music whereas the tempo of metronome tones did not affect performance.

Event-related potentials in a self-paced novelty oddball task.

The event-related potentials (ERPs) to the stimuli triggered by a participant's self-paced key press were compared with the ERPs to the same stimuli presented at an external pace. Fourteen participants responded to 2000 Hz target tones interspersed among 1000 Hz standard tones and various unique novel sounds. The amplitudes of the P3s elicited by target and novel stimuli were larger in the self-triggered condition than in the machine-triggered condition in which the stimuli were presented automatically with the same intervals as in the self-triggered condition. The effect was prominent at fronto-central scalp sites. When the timing of stimulus is unequivocal, a neural activity related to stimulus evaluation may increase and manifest itself as a large late positive ERP component.

Event-related potentials elicited by wrong terminal notes: effects of temporal disruption.

Wrong terminal notes of familiar musical phrases are known to elicit a large positive deflection of the event-related potential (ERP). The present study examined whether the effect of wrong terminal notes on ERP was modulated by the timing of their occurrence. Sixteen non-musicians were asked to rate the congruity of the endings of 50 well-known musical phrases. Four different types of endings were made for each phrase by manipulating the timing (well-timed vs. delayed for 750 ms) and pitch (correct vs. wrong) of the last note orthogonally. These ending patterns were presented equiprobably in an unpredictable order. Wrong notes elicited large late positive waves irrespective of the timing of occurrence. When the notes were delayed, however, the positive waves were reduced in amplitude to about 50% of those elicited by well-timed notes. These results suggest that the temporal (rhythmic) structure of musical phrases strongly influences the processing of melodic information.

Estimation of generator sources of human sleep spindles by dipole tracing method.

Equivalent dipole sources of two types of human sleep spindles (14 and 12 Hz) were investigated on five normal subjects. The present study showed that a sleep spindle can be represented by a single equivalent dipole. For both 14 and 12 Hz sleep spindles, the equivalent dipole sources were estimated near the thalamus. The orientation of the equivalent dipole of a 14 Hz sleep spindle was in the centro-parietal direction, while that of a 12 Hz sleep spindle was in the frontal direction. These results suggest that both types of sleep spindle activities are generated in the thalamus, and cortical de-arousal plays a modificatory role on their different topographical distributions.

Event-related potential correlates of individual differences in working memory capacity.

The capacity of working memory has been suggested to differ among people and these differences affect performance in a wide variety of cognitive tasks. This study explored electrophysiological correlates of individual differences in working memory capacity by means of event-related potentials. Thirty-four healthy students performed two- and five-choice reaction time tasks. In the two-choice reaction time (2CRT) task, two digits (3 and 7) were presented visually with probabilities of .20 and .80. In the five-choice reaction time (5CRT) task, five digits (3, 4, 5, 6, and 7) were presented equiprobably in a random order. Participants were required to press a button corresponding to each digit with a different finger. Working memory capacity of each participant was assessed by the reading span test originated by M. Daneman and P.A. Carpenter (1980). Participants with high reading span produced larger P300s than did persons with low reading span in the 5CRT task, but the difference was not significant in the 2CRT task. It had been suggested that individual differences in working memory capacity would affect initial stages of information processing as early as 300 ms after stimulus onset.

Background instrumental music and serial recall.

Although speech and vocal music are consistently shown to impair serial recall for visually presented items, instrumental music does not always produce a significant disruption. This study investigated the features of instrumental music that would modulate the disruption in serial recall. 24 students were presented sequences of nine digits and required to recall the digits in order of presentation. Instrumental music as played either forward or backward during the task. Forward music caused significantly more disruption than did silence, whereas the reversed music did not. Some higher-order factor may be at work in the effect of background music on serial recall.

Effect of taurine on the fatty liver of children with simple obesity.

This study elucidated the effect of taurine on fatty liver in simple obesity. Taurine was orally administered to 10 children with fatty liver. During taurine administration, the CT numbers of the liver, which were low in the beginning, increased. Serum ALT levels were improved, especially in those children whose weight was well controlled. Even in those who failed in weight control, serum ALT levels were slightly recovered. Ratios of glycine/taurine-conjugated bile acids were decreased. Thus, taurine was effective in treating fatty liver of children with simple obesity regardless of the success/failure of weight control. Taurine administration is considered to be helpful as an adjuvant therapy for fatty liver.

Docosahexaenoic acid status of patients with extrahepatic biliary atresia.

Docosahexaenoic acid (DHA) is believed to be an important long-chain polyunsaturated fatty acid (LCPUFA), which may be essential for neurofunction in infants. Patients with extrahepatic biliary atresia (EBA) may have DHA deficiency secondary to fat malabsorption. The authors investigated DHA and other LCPUFA levels in plasma and red blood cell (RBC) phospholipids of patients after the Kasai portoenterostomy and after supplementation with essential fatty acids. Ten children aged 8 to 17 months (mean, 12.6 months) comprised the study group. Five were jaundiced and five had a normal bilirubin level. The patients received 1 mL/kg of fat emulsions (10% Intralipid, containing 50% linoleic acid and 9% alpha-linolenic acid) in addition to an age-appropriate diet. Additional supplements were ursodeoxycholic acid (UDCA) (15 mg/kg/d) and taurine (100 mg/kg/d). The percentages of DHA in both plasma and RBC phospholipids of patients in the jaundiced group were significantly lower than those of normal children. Patients in the jaundice-free group had significantly lower levels of DHA and higher levels of linoleic acid in both plasma and RBC phospholipids in comparison to the normal group. This study shows that postoperative EBA patient become DHA-deficient even when supplemented with fat emulsions (largely composed of linoleic acid) that contain DHA's precursor, alpha-linolenic acid. This demonstrates a deficiency in the long-chain acid desaturase activity of these patients. It is recommended that excessive/linoleic acid intake be avoided and that all EBA patients have small amounts of DHA added to their lipid supplementation.

Effects of ursodeoxycholic acid treatment on essential fatty acid deficiency in patients with biliary atresia.

To assess whether ursodeoxycholic acid (UDCA) treatment has any beneficial effect on essential fatty acid (EFA) deficiency in patients who have had a Kasai operation for extrahepatic atresia (EBA), responses of serum fatty acids to UDCA administration (15 mg/kg/d) were investigated in eight jaundice-free patients and in eight patients with jaundice (serum total bilirubin > or = 1.0 mg/dL). All patients were also given taurine supplementation (100 mg/kg/d). Serum fatty acid composition was determined before and 6 months after UDCA treatment. Serum total bile acid concentration and serum total bilirubin value, as a part of conventional liver function tests, were measured before and during UDCA therapy. Before UDCA treatment, the concentrations of linoleic acid and arachidonic acid were significantly lower (P > .05 for the former; P > .01 for the latter) in both the jaundice and jaundice-free groups than in the controls. After 6 months of treatment, the linoleic acid concentration significantly increased (P > .05), to the normal range, in the jaundice-free group, but not in the jaundice group. The arachidonic acid concentration did not increase significantly in either group. The serum total bile acid concentration was lower in six of the eight jaundice-free patients and in four of the eight jaundice patients. The serum total bilirubin value decreased in six of the eight jaundice-free patients and in four of the eight jaundice patients; however, the degree of improvement was not statistically significant in either group. No side effects developed, and there were no changes in blood chemistry values unrelated to liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

1 beta-hydroxylated bile acids in the urine of healthy neonates.

In order to clarify the metabolism of bile acids in neonates, 1 beta-hydroxylated bile acids in the urine of healthy newborns were examined by gas chromatography-mass spectrometry. The results showed that the percentage of total 1 beta-hydroxylated bile acids, 3 beta, 12 alpha-dihydroxy-5-cholenoic acid and hyocholic acid in neonates was significantly higher than in older children. The ratio of 1 beta-hydroxylated bile acids to their comparable primary bile acids was also higher in neonates than in older children. These results suggest that 1 beta- and 6 alpha-hydroxylation of bile acids are the predominant pathways of bile acid metabolism in neonates.

Vitamin D metabolism in pre-operative extrahepatic biliary atresia.

In order to clarify the pathogenesis of rickets in preoperative patients with extrahepatic biliary atresia, we evaluated baseline serum 25-OHD and 1,25(OH)2D levels and correlated serum 25-OHD levels with increase in age and season of birth in 16 preoperative patients. Further, parenteral vitamin D2 tolerance tests were performed in 5 cases. Serum 25-OHD and 1,25(OH)2D levels were significantly lower than those in 15 normal controls. There was a negative correlation between the serum 25-OHD levels and increase in age. The patients born during the winter had lower serum 25-OHD concentrations than those born in summer. The mean value of increased 25-OHD levels after the parenteral vitamin D2 tolerance tests did not differ from that of 6 controls. Since there was no impairment of vitamin D 25-hydroxylation, the reduction in serum 25-OHD may therefore be mainly due to disturbed intestinal vitamin D absorption. It was also concluded that season of birth and increase in age are pathogenic factors in the etiology of rickets in preoperative patients with extrahepatic biliary atresia.

Abnormal low ratio of cholic acid to chenodeoxycholic acid in a cholestatic infant with severe hypoglycemia.

We report a premature infant with severe hypoglycemia (serum glucose: 6 mg/dl) and cholestasis (serum total bile acids: 211.55 mumol/L) caused by hypoplasia of the interlobular bile ducts. This patient had developed intracranial hemorrhage and sepsis while undergoing treatment for hypoglycemia. As a result of endocrine evaluation, we made a diagnosis of idiopathic panhypopituitarism, congenital absence or hypoplasia of the pituitary gland. Moreover, we found abnormal bile acid profiles: The ratio of cholic acid to chenodeoxycholic acid was abnormally low in serum (0.04) and in biliary bile (0.33). However, 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid and bile alcohols were not detected. We therefore suspected that the severe cholestasis and abnormal bile acid profiles in the serum and biliary bile in this patient were related to physiologic immaturity of the enterohepatic circulation of bile acids and immaturity of hepatic 12 alpha-hydroxylation.

Synthesis of 6-hydroxylated bile acids and identification of 3 alpha,6 alpha,7 alpha,12 alpha-tetrahydroxy-5 beta-cholan-24-oic acid in human meconium and neonatal urine.

Three 6-hydroxylated bile acids, 3 alpha,6 alpha,7 alpha,12 alpha-, 3 alpha,6 beta,7 alpha,12 alpha- and 3 alpha,6 beta,7 beta,12 alpha-tetrahydroxy-5 beta-cholan-24-oic acids, were synthesized from methyl cholate, and a sensitive method was developed for analyzing them by gas chromatography-mass spectrometry for the stoichiometric study of fetal bile acids. 3 alpha,6 alpha,7 alpha,12 alpha-Tetrahydroxy-5 beta-cholan-24-oic acid (6 alpha-hydroxylated cholic acid) was identified from human meconium and healthy neonatal urine by comparison with the mass spectrum of the reference compound. In human meconium, 6 alpha-hydroxylated cholic and chenodeoxycholic acids were determined in 1.2% and 29.0% of the total bile acids, respectively. We discuss the significance of hydroxylation at the C-1 beta and C-6 alpha positions of bile acids and their elimination in fetal and neonatal periods.

Ursodeoxycholic acid therapy in the treatment of biliary atresia.

The prognosis of operated biliary atresia in the cases with bile excretion chiefly depends upon the prevention of ascending cholangitis. An antibiotic is therefore intravenously administered during the early postoperative phase, but cannot be used over a long period. In the cases showing satisfactory bile excretion after operation, ascending cholangitis is rare because of rapid disappearance of jaundice. Regarding this, the authors prescribed ursodeoxycholic acid (UDCA) at 10-15 mg/kg/day to 6 infants with biliary atresia for several weeks after operation, and then determined the effects of UDCA in improving jaundice and bile excretion. As a result, serum bilirubin and serum total bile acid (STBA) levels were decreased in 4 of the 6 infants. In the remaining 2 infants, their STBA levels showed no decrease, but were rather increased; these infants subsequently died of hepatic failure. These results suggested that UDCA is useful in the treatment of cholestasis associated with biliary atresia in the cases attaining postoperative bile excretion. It was also suggested that the treatment with UDCA should be stopped when the STBA levels increased after the beginning of the treatment. Therefore, it was thought that STBA levels measured during UDCA therapy could serve as a good indicator of the choleretic effect of UDCA.