Yuhei Ichimaru

Development of the polysomnographic database on CD-ROM.

We have developed a polysomnographic database on CD‐ROM. The data were obtained from 16 subjects with sleep apnea syndrome. The physiological signals include electroencephalogram, electromyogram, electrooculogram, invasive blood pressure, respiratory wave, oxygen saturation, and cardiac volume as measured by VEST method. The CD‐ROM also include programs to analyze polysomnography (PSG) data. The CD‐ROM has values: (i) for researchers investigating clinical physiology or non‐linear dynamics during sleep apnea syndrome; (ii) for engineers developing a new algorithm for the computerized analysis of PSG data related to sleep apnea syndrome; (iii) for students learning sleep physiology.

Possible role of preproghrelin gene polymorphisms in susceptibility to bulimia nervosa

Previous investigations have suggested that ghrelin, an endogenous orexigenic peptide, is involved in the pathology of eating disorders. We conducted a study to determine whether any preproghrelin gene polymorphisms are associated with eating disorders. Three hundred thirty‐six eating disorder patients, including 131 anorexia nervosa (AN)‐restricting types (AN‐R), 97 AN‐binge eating/purging types (AN‐BP) and 108 bulimia nervosa (BN)‐purging types (BN‐P), and 300 healthy control subjects participated in the study. Genotyping was performed to determine the polymorphisms present, and with this information, linkage disequilibrium (LD) between the markers was analyzed and the distributions of the genotypes, the allele frequencies, and the haplotype frequencies were compared between the groups. The Leu72Met (408 C > A) (rs696217) polymorphism in exon 2 and the 3056 T > C (rs2075356) polymorphism in intron 2 were in LD (D′ = 0.902, r2 = 0.454). Both polymorphisms were significantly associated with BN‐P (allele‐wise: P = 0.0410, odds ratio (OR) = 1.48; P = 0.0035, OR = 1.63, for Leu72Met and 3056 T > C, respectively). In addition, we observed a significant increase in the frequency of the haplotype Met72‐3056C in BN‐P patients (P = 0.0059, OR = 1.71). Our findings suggest that the Leu72Met (408 C > A) and the 3056 T > C polymorphisms of the preproghrelin gene are associated with susceptibility to BN‐P.

No association of brain‐derived neurotrophic factor Val66Met polymorphism with anorexia nervosa in Japanese

The Met66 allele of the Val66Met polymorphism in the brain‐derived neurotrophic factor (BDNF) gene has been reported to be associated with anorexia nervosa (AN), and also lower minimum body mass index (BMI) and higher harm avoidance in AN. We genotyped the Val66Met polymorphism (rs6265) in 689 AN cases and 573 control subjects. There were no significant differences in the genotype or allele frequencies of the Val66Met between AN and control subjects (allele wise, odds ratio = 0.920, 95% CI 0.785–1.079, P = 0.305). No difference was found in minimum BMIs related to Val66Met in AN (one‐way ANOVA, P > 0.05). Harm avoidance scores on the Temperament and Character Inventory were lower in the Met66 allele carriers (P = 0.0074) contrary to the previous report. Thus we were unable to replicate the previous findings that the Met66 allele of the BDNF is associated with AN and that the minimum BMI is lower or the harm avoidance score is higher in AN patients with the Met66 allele.

The effects of postural changes of baroreflex gain in normal and hypertensive pregnancies.

In order to understand the changes of baroreflex gain due to postural changes in normal pregnancies, we measured percentage changes (% changes) in blood pressure (SBP, DBP), heart rate (HR), stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR) as well as cardiac autonomic nervous function (HF as an index of parasympathetic and LF/HF as an index of sympathetic function) and compared these parameters in normal pregnancies with those found in hypertensive pregnancies, such as chronic hypertensive (CHP) and severe preeclamptic pregnancies (PE), in late pregnancy (after 32 wks). When the position was changed from supine to standing in normal and non-pregnant women, the % changes of HR, DBP, TPR and LF/HF were increased and SBP, SV, CO and HF were decreased. The % changes of these parameters, however, were gradually decreased as pregnancy progressed, especially after 20–24 wks of gestation. In hypertensive pregnancies, however, even in late pregnancy, the decreased SBP and increased TPR was still observed and the profound decrease of CO and SV and increase of TPR were characteristic in PE when compared to CHP.

Association of the c.385C>A (p.Pro129Thr) polymorphism of the fatty acid amide hydrolase gene with anorexia nervosa in the Japanese population.

The functional c.385C>A single‐nucleotide polymorphism (SNP) in the fatty acid amide hydrolase (FAAH) gene, one of the major degrading enzymes of endocannabinoids, is reportedly associated with anorexia nervosa (AN). We genotyped the c.385C>A SNP (rs324420) in 762 lifetime AN and 605 control participants in Japan. There were significant differences in the genotype and allele frequencies of c.385C>A between the AN and control groups. The minor 385A allele was less frequent in the AN participants than in the controls (allele‐wise, odds ratio = 0.799, 95% confidence interval [CI] 0.653–0.976, P = 0.028). When the cases were subdivided into lifetime restricting subtype AN and AN with a history of binge eating or purging, only the restricting AN group exhibited a significant association (allele‐wise, odds ratio = 0.717, 95% CI 0.557–0.922, P = 0.0094). Our results suggest that having the minor 385A allele of the FAAH gene may be protective against AN, especially restricting AN. This finding supports the possible role of the endocannabinoid system in susceptibility to AN.

Possible participation of extracellular calcium-sensing receptor in blood pressure regulation in rats.

The concentration of calcium in the cerebrospinal fluid (CSF) affects systemic blood pressure; an increase in calcium concentration lowers blood pressure, whereas a decrease raises it. Although this phenomenon has been known for more than 50 years, the precise mechanism is not completely understood. We examined whether the extracellular calcium-sensing receptor (CaSR), which was originally cloned from the parathyroid cells and later found in the brain, contributes to blood pressure regulation by calcium in the CSF. In urethane-anesthetized and artificially ventilated Wistar-Kyoto rats, an intracisternal injection of NPS R-467, an allosteric CaSR activator, decreased blood pressure associated with sympatho-inhibition in a dose-dependent manner. Treatment with an inactivator of the CaSR elicited an increase in blood pressure. Similar results were observed in awake and freely moving animals. In contrast, when the CaSR activator/inactivator was administered into the lateral ventricle, the cardiovascular changes were minimal. These results indicate that the CaSR in the brain contributes, at least in part, to the hypotensive effect of centrally administered calcium and suggests that the CaSR in the lower brainstem participates in tonic regulation of blood pressure by sensing a change in the CSF Ca²+ concentration.

Development of an analysis system for 24-hour blood pressure and heart rate variability in the rat

Abstract We have developed a system to evaluate 24‐h changes of heart rate (HR) and blood pressure variability (BPV) in free moving rat. As a sensor to monitor electrocardiogram, we used the telemetry system. Analog data were sent to an analog to digital converter directly. The data were digitized at a sampling frequency of 1250 Hz and digitally stored on a computer. RR‐intervals (difference of successive RR in electrocardiogram) were calculated using custom designed programs. Circadian change of the blood pressure and heart rate variability were calculated. We suggest that the system is a powerful tool in the evaluation of circadian changes of hemodynamics and autonomic nervous function in free moving rats.

Non-dipping blood pressure variations in adult Kazakhs are derived from decreased daytime physical activity and increased nighttime sympathetic activity.

Abstract Many of the elderly Kazakhs have been found to exhibit non-dipping blood pressure variations (BPV). Such variations are seen in both normotensive and hypertensive Kazakhs. The purpose of this study was (1) to determine whether middle–aged Kazakhs also include large numbers of non-dippers, (2) to compare the characteristics of non-dipping and dipping, and (3) to clarify the mechanisms responsible for non-dipping type BPV by examining the autonomic nervous activity and physical activity. We performed ambulatory blood pressure (BP) monitoring. The subjects were divided into two groups (dipping and non-dipping type). We monitored the subjects’ physical activity with accelerometry and assessed their autonomic nerve activity by performing a frequency domain analysis of their heart rate variability (HRV). The power spectral density (PSD) of the HRV was calculated using fast Fourier transformation. We analyzed the systolic blood pressure (SBP) variations with the maximum entropy method (MEM). The dippers and non-dippers accounted for 48% and 52% of the subjects, respectively. MEM analysis revealed that the SBP variations of the non-dippers exhibited a 24 hour periodicity with a very weak PSD as well as an ultradian periodicity. The non-dippers exhibited higher low-frequency/high-frequency (LF/HF) ratio and lower HF/(LF + HF) ratios than the dippers, particularly during the nighttime. In addition, the non-dippers performed less physical activity than the dippers. These differences in cardiac autonomic function and physical activity might contribute to the generation of a weak circadian rhythm in SBP, and thus, ultimately lead to the non-dipping SBP variations observed in non-dipper Kazakhs.