Biomedical subjects

I Hirota

Publications and source records attributed to I Hirota.

At least 19 recordsLinked to original sources

PubMed1999

Multiple cardiovascular risk factors in obstructive sleep apnea syndrome patients and an attempt at lifestyle modification using telemedicine-based education.

Severe obstructive sleep apnea syndrome (OSAS) is a typical 'lifestyle-related disease' characterized by a high incidence of cardiovascular risk factors, such as obesity, smoking, hypertriglyceridemia, and diabetes mellitus. Patients with OSAS tend to have eating disorders as a result of efforts to overcome the intolerable sleepiness. Treatment of OSAS should therefore aim to improve the lifestyle through encouraging weight reduction, physical activity increase, and tobacco avoidance, in addition to direct therapy such as continuous positive airway pressure for upper airway obstruction. The telemedicine system we developed was considered to be effective for providing home-based education on nutrition and exercise aimed at correcting multiple risk factors in OSAS patients

Adult↗

PubMed1996

Augmented very low frequency component of heart rate variability during obstructive sleep apnea.

After documenting the presence of obstructive sleep apnea syndrome (OSAS) through polysomnographic monitoring, we performed simultaneous ambulatory recordings of electrocardiogram, oronasal airflow, and pulse oximetry on 12 OSAS patients with normal autonomic nervous function for a period of 24 hours. The power spectrum of heart rate variability was investigated before and during treatments using dental appliances. Freuquency domain analysis showed that the very low frequency component of heart rate (0.008-0.04 Hz) was increased in OSAS patients and that a very low frequency peak appeared during episodes of obstructive sleep apnea. The increase in very low frequency identification was synchronized with episodes of absence of air exchange or hypoxemia (decreased arterial oxygen saturation) that occurred repeatedly at a cycle length of 25-120 seconds in our subjects. Frequency domain analysis of heart rate variability before and during prosthetic mandibular advancement treatment showed that only the very low frequency was significantly decreased during prosthetic mandibular advancement treatment, whereas the other frequencies, i.e. high, low, and ultralow frequency component values, showed no significant changes. Time domain analysis of heart rate variability before and during prosthetic mandibular advancement treatment showed no significant changes in any of these parameters. Frequency domain analysis of heart rate variability during nocturnal sleep, especially investigation of very low frequency and very low frequency peak, can be a noninvasive low-cost approach to diagnose and even better monitor subjects undergoing treatment at home, particularly considering that R-R intervals can be extracted from pulse oximetry and that analysis software programs are already commercially available.

Adult↗

PubMed1995

Deoxycholic acid in gall bladder bile does not account for the shortened nucleation time in patients with cholesterol gall stones.

The relations between the concentration of deoxycholic acid (DCA), the cholesterol saturation index, and the nucleation time in gall bladder bile were measured to determine the role of DCA in bile in the pathogenesis of cholesterol gall stone disease. Bile was obtained from patients with cholesterol gall stones (n = 30), subjects without gall stones (n = 35), and patients with pigment gall stones (n = 9). Three of 30 cholesterol gall stone patients and 10 of 35 gall stone free subjects were treated with antibiotics by mouth to decrease the concentration of bile DCA and determine the effect of DCA on biliary lithogenecity. Both the percentage and concentration of DCA in bile were similar in patients with and without cholesterol gall stones despite significant differences in their cholesterol saturation indices and nucleation times. Neither the percentage nor the concentration of DCA in bile correlated with either the cholesterol saturation index or the nucleation time. Analysis of subgroups with matching cholesterol saturation indices showed no correlation between the proportion of DCA in the bile and the cholesterol nucleation time. The proportion of DCA in bile was decreased by antibiotic treatment, but this had no effect on the cholesterol saturation index or nucleation time. These results suggest that DCA in bile is not responsible for biliary cholesterol saturation or cholesterol nucleation time.

Aged↗

PubMed1993

High vesicular cholesterol and protein in bile are associated with formation of cholesterol but not pigment gallstones.

To examine the differentiating parameters between cholesterol and pigment gallstones, we compared the nucleation times, concentrations of biliary lipid and protein, and the distribution of vesicular cholesterol in gallbladder bile of 16 patients with cholesterol, eight patients with black pigment gallstones, and nine gallstone-free control patients. Cholesterol monohydrate crystals were present in the fresh bile of only the cholesterol gallstone group. The nucleation time was significantly faster in the cholesterol stone group (3.3 +/- 3.2 days) than in the other two groups (pigment stone: 15.8 +/- 6.6, control: 16.9 +/- 5.7). The cholesterol saturation indices and the distribution of vesicular cholesterol were significantly higher in the cholesterol gallstone group than those in the other two groups. The total biliary protein concentration was significantly (P < 0.01) higher in the cholesterol gallstone group [2.57 +/- 1.91 (SD) mg/ml] than that in the black pigment stone group (1.09 +/- 0.59). All parameters in patients with black pigment gallstone were essentially similar to the controls. We conclude that the presence of cholesterol crystals, rapid nucleation time, high vesicular cholesterol distribution, elevated cholesterol saturation index, and high protein concentration are associated with cholesterol gallstones but not with black pigment gallstones.

Aged↗

PubMed1993

Cholesterol crystal appearance time of gallbladder bile in middle-aged women.

The aim of our study was to examine the hypothesis that the cholesterol nucleation time of gallbladder bile might be rapid in women in their fourth and fifth decades, which increases their risk of cholesterol gallstones. Fifty-four gallbladder bile samples were collected from gallstone-free patients and patients with cholesterol gallstones in a functioning gallbladder. We examined the relations of nucleation time to age and sex in each group. The nucleation time of gallbladder bile tended to be prolonged with age, but there was no correlation between nucleation time and age in each group. Cholesterol nucleation time was not significantly different between age-matched females and males in each group, nor was it faster in middle-aged females than in older females. Thus, nucleation time was not rapid in middle-aged females even in the gallstone-free group. These results indicate that cholesterol nucleation time is not significantly influenced by either sex or age, and cannot therefore account for the higher frequency of cholesterol gallstone disease in females in the fourth and fifth decades.

Age Factors↗

PubMed1992

Activity of cholesterol in human gallbladder bile in relation to nucleation of cholesterol monohydrate crystals.

To examine the hypothesis that the chemical activity of cholesterol molecules reflects the amount of cholesterol phasing out from bile associating with cholesterol monohydrate crystal nucleation, the cholesterol activities in human gallbladder biles from cholesterol gallstone patients, either untreated or treated with ursodeoxycholic acid, and from gallstone-free patients were determined in relation to the nucleation time and vesicular lipid composition. The cholesterol activity (nmol/disc/h) determined by the polyethylene disc uptake method was higher in the untreated gallstone group than the gallstone-free group (P less than 0.05) and the ursodeoxycholic acid treated group (P less than 0.01). The cholesterol activity correlated negatively with the nucleation time (P less than 0.01) and positively with both the vesicular cholesterol concentration (P less than 0.05) and the cholesterol/phospholipid ratio in vesicles (P less than 0.05). After the separation of vesicles from micelles by gel filtration, the cholesterol activity in the vesicular phase was found to be similar to that in the micellar phase. Interestingly, both the activities of cholesterol in the vesicular and micellar phases were significantly higher in the untreated gallstone group than in the gallstone-free group (P less than 0.05). These results suggest that cholesterol activity represents the amount of thermodynamically unstable cholesterol in bile.

Aged↗

PubMed1992

Decreased protein concentration and improved metastability of bile induced by ursodeoxycholate.

Previous studies demonstrated that higher biliary protein is associated with reduced metastability of bile. This study attempted to examine the induced effect of ursodeoxycholate on metastability of bile by measuring the nucleation time and biliary protein in cholesterol gallstone patients. Thirty-seven patients with functioning gallbladders were studied 10 control patients without gallstones and 27 with cholesterol gallstones. Ten of 27 cholesterol gallstone patients were treated with ursodeoxycholate (600 mg/day) prior to surgery. Twelve of 17 untreated gallstone patients had cholesterol crystals in gallbladder bile while cholesterol crystals were absent in the ursodeoxycholate-treated gallstone patients and in the controls. Total protein concentration and cholesterol saturation index were significantly greater in the untreated gallstone patients with crystals than in those without crystals in bile. The treatment with ursodeoxycholate significantly decreased biliary protein concentration and cholesterol saturation index associated with the prolonged nucleation time. Cholesterol nucleation time correlated with biliary total protein concentration and cholesterol saturation index but not with total lipid concentration. It is concluded from the present study that ursodeoxycholate decreases biliary protein thereby partly increasing metastability of gallbladder bile.

Bile↗

PubMed1992

Effect of chenodeoxycholate and ursodeoxycholate on nucleation time in human gallbladder bile.

The effects of treatment with chenodeoxycholic acid (CDCA) or ursodeoxycholic acid (UDCA) on nucleation time, biliary lipid concentration, and vesicular lipid composition were studied. Gallbladder bile was collected at the time of surgery from 33 cholesterol gallstone patients who were divided into three groups: 16 untreated, 9 pretreated with CDCA (400 mg/day), and 8 pretreated with UDCA (600 mg/day) for 1-3 weeks before surgery. Control bile samples were also collected from nine patients without cholelithiasis. Nucleation time was prolonged significantly in both CDCA- and UDCA-treated groups [12.6 +/- 8.5 (SD) and 21.0 +/- 0 days, respectively] compared with the untreated gallstone group (3.3 +/- 3.2 days). Both treatments significantly decreased the proportion and concentration of both cholesterol and phospholipids present in the vesicular phase. Treatment with UDCA decreased the cholesterol saturation index more than did CDCA at the dose used in this study. In the CDCA-treated group, patients without much change in cholesterol saturation index (greater than 1.0) showed a prolongation of the nucleation time with a significant decrease in vesicular cholesterol concentration, indicating a shift of cholesterol from vesicles to micelles. UDCA-treated patients and CDCA-treated patients with decreased cholesterol saturation index (less than 1.0) showed a greater effect. The authors conclude that UDCA prolongs the nucleation time mainly by decreasing the cholesterol saturation index, whereas CDCA does so by the dual effect of lowering the cholesterol saturation index and shifting cholesterol from vesicles to micelles.

Bile↗

PubMed1992

Human gallbladder bile becomes lithogenic during short-term intravenous hyperalimentation.

Biliary sludge formation is reported to be one of the complications of intravenous hyperalimentation (IVH); however, the change in human biliary lithogenicity during IVH treatment has been little studied. To clarify the pathogenesis of IVH-induced biliary sludge, we determined biliary lipid composition, vesicular cholesterol concentration, and nucleation time using gallbladder bile samples collected from three groups: The IVH group comprised 9 patients who received IVH with fasting for a period of 2-8 days prior to surgery for gastrointestinal diseases. The control group comprised 10 patients operated after overnight fasting for gastrointestinal diseases. The cholesterol gallstone group comprised 14 patients surgically treated for cholesterol gallstone disease after overnight fasting. The nucleation time in the IVH group was significantly shorter (7.8 +/- 5.3 days, mean +/- SD) than that in the control group (17.3 +/- 5.5 days), while it did not reach the value in the cholesterol gallstone group (3.1 +/- 3.3 days). The cholesterol saturation index in the IVH group (1.01 +/- 0.27) was higher but not significantly different compared with the control group (0.80 +/- 0.21). The concentrations of biliary lipids and individual bile acid were similar in the IVH and control groups. The vesicular cholesterol concentration in the IVH group (3.0 +/- 2.1 mM) was significantly higher than that in the control group (0.9 +/- 1.0 mM). In conclusion, IVH with fasting causes a rapid cholesterol nucleation time and a higher vesicular cholesterol concentration, thereby inducing an initial stage of gallbladder sludge formation.

Aged↗

PubMed1992

Diurnal variation in cholesterol metastability of hepatic bile and its acute modulation with ursodeoxycholic acid in humans.

We studied the alteration of cholesterol metastability of hepatic bile caused by diurnal variations in hepatic biliary lipid excretions and acutely induced changes following ursodeoxycholic acid (UCDA) administration. Hepatic bile was collected at 6-h intervals for 24 h from 6 patients with an indwelling choledochal drainage before and after UDCA administration. A basal diurnal variation showed the highest cholesterol saturation index (p < 0.05) and cholesterol distribution in vesicles (p < 0.01) and the shortest nucleation time (p < 0.05) in the early morning. After the ingestion of ursodeoxycholic acid for 1 day, early morning biliary cholesterol concentrations were reduced. Interestingly, significant decreases in vesicular cholesterol concentrations (1.0 +/- 0.2 to 0.1 +/- 0.04 mM, p < 0.01) and in the vesicular cholesterol/phospholipid ratio (1.6 +/- 0.1 to 0.7 +/- 0.1, p < 0.05) were associated with prolongation of the nucleation time (11.5 +/- 1.2 to 18.7 +/- 1.5 days, p < 0.01). Biliary protein had no diurnal variations and did not decrease significantly with UCDA. These results indicate that during a day the early morning hepatic bile is the most unstable and that UCDA acutely enhances hepatic biliary metastability mainly by decreasing the rate of vesicular cholesterol saturation.

Aged↗

PubMed1990

Biliary lipids and bile acid composition before and after endoscopic sphincterotomy.

The effect induced by endoscopic sphincterotomy on biliary lipids and bile acid composition was examined by following up the seven patients prior to early (1-2 week) and late (0.5-1 year) after the endoscopic sphincterotomy. The concentrations of total bile acids, phospholipid and cholesterol were essentially constant throughout the one-year observation period. Cholesterol saturation indices were not significantly altered. No bile acid concentration changed significantly. The results indicate that endoscopic sphincterotomy has little undesirable effect on the biliary lipids and bile acid compositions over an observed period.

Adult↗

PubMed1986