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.

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.

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.

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 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.

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.

Conjugating ability of bile acids in hepatic failure

A 5-month-old boy with giant cell hepatitis died of hepatic failure. Analysis of serum bile acids by high pressure liquid chromatography revealed a marked increase in total bile acid concentration and a decrease in the cholate to chenodeoxycholate ratio. However, contrary to expectation, the conjugating ability of bile acids with taurine or glycine was well preserved. This suggests that the amino acid conjugation can occur despite the presence of severe hepatocellular damage.

Sulfated and nonsulfated bile acids in urine of patients with biliary atresia: analysis of bile acids by high-performance liquid chromatography

To elucidate urinary bile acid patterns in patients with biliary atresia (BA), 15 sulfated and nonsulfated bile acids in urine were separately measured by high-performance liquid chromatography. This relatively simple technique for fluorescence detection utilizes the enzyme 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) to reveal urinary bile acid patterns. By this method, recovery rates of sulfated and nonsulfated bile acids in urine were satisfactory, and this analysis was shown to be applicable to clinical situations. In 10 patients with BA, the mean level of total bile acids in urine (23.35 +/- 18.51 mumol/day) was seven times higher than the mean level in eight normal infants (3.05 +/- 2.05 mumol/day). In the infants with BA, the mean level of total sulfated bile acids was about half of the total bile acid level. The main components of urinary nonsulfated bile acids in BA were glycocholic acid (6.21 +/- 5.55 mumol/day) and taurocholic acid (2.28 +/- 1.33 mumol/day), whereas the main components of the urinary sulfated bile acids were glycochenodeoxycholic acid (4.58 +/- 6.97 mumol/day) and taurochenodeoxycholic acid (3.67 +/- 3.54 mumol/day). Chenodeoxycholic acid, which is relatively toxic to the liver, may more easily be conjugated with sulfate and, hence, excreted into urine at a faster rate than cholic acid. Marked individual variations in urinary bile acid patterns were observed not only in BA patients but also in normal controls.

Investigation of serum bile acids; seven patients with Alagille syndrome

To clarify whether an abnormal bile acid pattern has a role in the pathogenesis of Alagille syndrome, we compared serum bile acid patterns in seven with Alagille syndrome with those of patients with congenital biliary atresia (CBA), neonatal hepatitis (NH) and normal infants. Of the seven patients with Alagille syndrome, four patients were younger and three were older than 1 year. The mean total serum bile acid level in the infants was higher than in older subjects. There was a dissociation between the levels of serum total bile acid and bilirubin in three of the seven cases. The mean total bile acid levels in serum were in the following decreasing order: CBA, Alagille syndrome, NH and controls. The ratio of cholate to chenodeoxycholate in the younger patients with Alagille syndrome was significantly higher than CBA (P less than 0.001). However, no specific bile acid pattern was found in Alagille syndrome by high-performance liquid chromatography (HPLC).

Serum concentrations of glucuronidated and sulfated bile acids in children with cholestasis

Serum concentrations of nonglucuronidated-nonsulfated, glucuronidated, and sulfated bile acids in 9 control children and 16 children with cholestasis were quantitated by mass fragmentography. Total bile acid levels in control children were 19.55 +/- 2.78 mumol/liter (mean +/- SEM), and glucuronidated and sulfated bile acids comprised 2.6 +/- 0.5 and 17 +/- 3.1%, respectively. In 9 patients with congenital biliary atrasia, total bile acid levels were 167.34 +/- 11.18 mumole/liter of which 2.1 +/- 0.3% were glucuronidated and 15 +/- 1.4% were sulfated. Lithocholic and 3 beta-hydroxy-5-cholenoic acids, which have hepatotoxic effects, were presented in only small amounts in cholestatic children, and they were almost all glucuronidated or sulfated. The percentages of glucuronidated bile acids in control and cholestatic children were lower than in healthy and cholestatic adults, which may be explained by the lower activity of UDP-glucuronyltransferase in neonatal liver.

Experimental study of the pathogenesis of choledochal cyst and pancreatitis, with special reference to the role of bile acids and pancreatic enzymes in the anomalous choledocho-pancreatico ductal junction

To investigate the mechanisms initiating pancreatic enzyme activation followed by the development of a choledochal cyst and/or pancreatitis under anomalous choledocho-pancreatic ductal junction (ACPDJ), choledocho-pancreatic end-to-side ductal anastomosis was successfully performed in 40 puppies as an experimental model of ACPDJ. As a result, reflux of pancreatic juice into the common bile duct readily and continuously occurred, and all pancreatic enzymes in bile obtained from the common bile duct were activated. Total bile acids increased about 2 months after surgery, and the ratio of taurodeoxycholic acid to total bile acids increased within the first months after surgery. Various degrees of common bile duct dilatation developed in all puppies within 7 to 10 days after the surgery, and no further dilatation occurred in the subsequent period. Histological change in the pancreatic duct was less prominent than that in the common bile duct, but histologically proved chronic pancreatitis was found in three of 23 sacrificed dogs, in which there was strong evidence of free and massive regurgitation of the bile-pancreatic juice mixture between the bile and the pancreatic duct systems. These findings in this experimental study constitute the first step to prove that ACPDJ, which is often found in patients with choledochal cyst, is an important etiologic factor not only for choledochal cyst but also for pancreatitis, and bile acids play an important role in the mechanism of pancreatic enzyme activation under the condition of ACPDJ.

Choledochopancreatic elongated common channel disorders

A choledochopancreatic end-to-side ductal anastomosis was successfully performed in 40 puppies as an experimental animal model of choledochopancreatic elongated common channel disorders. Follow-up periods were up to 1 year after surgery. Fusiform dilatation was developed in all puppies. The dilatation was completed within 1 week after surgery and did not increase its size after that. Also, all puppies developed pancreatic juice reflux into the bile duct. As for the etiology of the dilatation of the bile duct, temporary stricture of anastomosis was a more important factor than the pancreatic juice reflux in our models. In the biliopancreatic juice, we found no significant change of bile acid analysis between the control and our operated puppies, but almost all pancreatic enzyme activities were elevated. Bile acid was considered to play an important role in the activation of pancreatic enzymes. Epithelial hyperplasia was the only significant pathological change in the bile duct wall. Definite chronic pancreatitis developed in one puppy 16 months after surgery and was considered to be caused by the reflux of bile into the pancreatic duct. The action of biliopancreatic juice to both the bile duct and to the pancreas was mild and chronic.

[The correlation between the biliary excretion of cefmetazole and the bile acid metabolism in postoperative patients with biliary atresia]

The correlation between the biliary excretion of cefmetazole (CMZ) and the bile acid metabolism was studied in 17 postoperative children with congenital biliary atresia. B (total bile acid value in bile)/S (total bile acid value in serum) ratio is the best indicator in order to evaluate the postoperative condition of the liver in patients with biliary atresia at this time, that is, the B/S ratio is lower, the condition of the liver is deteriorated. The biliary excretion of CMZ was closely correlated to the B/S ratio, that is, the B/S ratio is lower, the biliary excretion of CMZ is discussed.

Antibiotic excretion into the bile after hepatic-portojejunostomy in biliary atresia

Antibiotic excretion into the bile was studied using LMOX and CMZ in 16 postoperative cases of biliary atresia patients who had had hepatic portoenterostomy with Suruga II type enterostomy with the following results: Group I: Excellent excretion which was almost the same as that seen with adult patients; Group IIa: Good or poor excretion, depending on the amount of bile flow and liver function; Group IIb: Very poor excretion; Group III: Good excretion but depending on the amount of bile flow and liver function. As the total bile acid level in bile showed a higher level, the biliary excretion of antibiotics was greater. Our study indicates that antibiotic excretion into the bile in infants is closely related to the condition of the liver function and the biliary passages.