Species-specificity of a panel of prion protein antibodies for the immunohistochemical study of animal and human prion diseases.

Monoclonal antibodies to the prion protein (PrP) have been of critical importance in the neuropathological characterization of PrP-related disease in men and animals. To determine the influence of species-specific amino-acid substitutions recognized by monoclonal antibodies, and to investigate the immunohistochemical reactivity of the latter, analyses were carried out on brain sections of cattle with bovine spongiform encephalopathy, sheep with scrapie, mice infected with scrapie, and human beings with Creutzfeldt-Jakob disease (CJD) or Gerstmann-Sträussler-Sheinker disease (GSS). Immunoreactivity varied between the antibodies, probably as the result of differences in the amino-acid sequence of the prion protein in the various species. Some monoclonal antibodies against mouse recombinant PrP gave strong signals with bovine, ovine and human PrP(Sc), in addition to murine PrP(Sc), even though the amino-acid sequences determined by the antibody epitope are not fully identical with the amino-acid sequences proper to the species. On the other hand, in certain regions of the PrP sequence, when the species-specificity of the antibodies is defined by one amino-acid substitution, the antibodies revealed no reactivity with other animal species. In the region corresponding to positions 134-159 of murine PrP, immunohistochemical reactivity or species-specificity recognized by the antibodies may be determined by one amino acid corresponding to position 144 of murine PrP. Not all epitopes recognized by a monoclonal antibody play an important role in antigen-antibody reactions in immunohistochemistry. The presence of the core epitope is therefore vital in understanding antibody binding ability.

Deletion of c-myb exon 9 induced by insertion of repeats.

A simple repeat was found to be inserted into exon 9 of the c-myb gene in three out of 20 bovine T lymphomas. The repeat was composed of multiple copies of a 12-nucleotide motif and had no significant homology to the sequences reported so far. Tumor cells containing the repeat expressed two kinds of c-myb mRNA: (1) are that included the repetitive sequence in exon 9, and (2) are that lacked the whole sequence of exon 9. Transfection of an expression vector containing exon and intron sequences and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of the mRNA demonstrated that the insertion of the repeat enhanced exon skipping of the transfected minigene. These observations imply that the insertion of the repeat may enhance exon skipping of the c-myb pre-mRNA. Although the transcription-activating activity by the c-Myb with the repeat was low, that by the c-Myb without exon 9 was three- to eightfold higher than the wild-type c-Myb. These data suggest that insertion of the 12-nucleotide repeat in codon 359 may result in c-Myb proteins having high- and low-transcription-activating activity.

Depressive mood is independently related to stroke and cardiovascular events in a community.

By means of a multivariate Cox model, we investigated the predictive value of a depressive mood on vascular disease risk in middle-aged community-dwelling people. In 224 people (88 men and 136 women; mean age: 56.8 +/- 11.2 years) of U town, Hokkaido (latitude: 43.45 degrees N, longitude: 141.85 degrees E), a chronoecological health watch was started in April 2001. Consultations were repeated every 3 months. Results at the November 30, 2004 follow-up are presented herein. 7-day/24-h blood pressure (BP) and heart rate (HR) monitoring started on a Thursday, with readings taken at 30-min intervals between 07:00 h and 22:00 h and at 60-min intervals between 22:00 h and 07:00 h. Data stored in the memory of the monitor (TM-2430-15, A and D company, Japan) were retrieved and analyzed on a personal computer with a commercial software for this device. Subjects were asked to answer a self-administered questionnaire inquiring about 15 items of a depression scale, at the start of study and again after 1-2 years. Subjects with a score higher by at least two points at the second versus first screening were classified as having a depressive mood. The other subjects served as the control group. The mean follow-up time was 1064 days, during which four subjects suffered an adverse vascular outcome (myocardial infarction: one man and one woman; stroke: two men). Among the variables used in the Cox proportional hazard models, a depressive mood, assessed by the Geriatric Depression Scale (GDS), as well as the MESOR of diastolic (D) BP (DBP-MESOR) and the circadian amplitude of systolic (S) BP (SBP-Amplitude) showed a statistically significant association with the occurrence of adverse vascular outcomes. The GDS score during the second but not during the first session was statistically significantly associated with the adverse vascular outcome. In univariate analyses, the relative risk (RR) of developing outcomes was predicted by a three-point increase in the GDS scale (RR = 3.088, 95% CI: 1.375-6.935, P = 0.0063). Increases of 5 mmHg in DBP-MESOR and of 3 mmHg in SBP-Amplitude were associated with RRs of 2.143 (95% CI: 1.232-3.727, P = 0.0070) and 0.700 (95% CI: 0.495-0.989, P = 0.0430), respectively. In multivariate analyses, when both the second GDS score and the DBP-MESOR were used as continuous variables in the same model, GDS remained statistically significantly associated with the occurrence of cardiovascular death. After adjustment for DBP-MESOR, a three-point increase in GDS score was associated with a RR of 2.172 (95% CI: 1.123-4.200). Monday endpoints of the 7-day profile showed a statistically significant association with adverse vascular outcomes. A 5 mmHg increase in DBP on Monday was associated with a RR of 1.576 (95% CI: 1.011-2.457, P = 0.0446). The main result of the present study is that in middle-aged community-dwelling people, a depressive mood predicted the occurrence of vascular diseases beyond the prediction provided by age, gender, ABP, lifestyle and environmental conditions, as assessed by means of a multivariate Cox model. A depressive mood, especially enhanced for 1-2 years, was associated with adverse vascular outcomes. Results herein suggest the clinical importance of repetitive assessments of a depressive mood and the need to take sufficient care of depressed subjects. Another result herein is that circadian and circaseptan characteristics of BP variability measured 7-day/24-h predicted the occurrence of vascular disease beyond the prediction provided by age, gender, depressive mood and lifestyle, as assessed by means of a multivariate Cox model. Earlier, we showed that the morning surge in BP on Mondays was statistically significantly higher compared with other weekdays. Although a direct association between the Monday surge in BP and cardiovascular events could not be demonstrated herein, it is possible that the BP surge on Monday mornings may also trigger cardiovascular events. We have shown that depressive people exhibit a more prominent circaseptan variation in SBP, DBP and the double product (DP) compared to non-depressed subjects. In view of the strong relation between depression and adverse cardiac events, studies should be done to ascertain that depression is properly diagnosed and treated. Chronodiagnosis and chronotherapy can reduce an elevated blood pressure and improve the altered variability in BP and HR, thus reducing the incidence of adverse cardiac events. This recommendation stands at the basis of chronomics, focusing on prehabilitation in preference to rehabilitation, as a public service offered in several Japanese towns.

Arterial stiffness independently predicts cardiovascular events in an elderly community -- Longitudinal Investigation for the Longevity and Aging in Hokkaido County (LILAC) study.

We investigated the predictive value of arterial stiffness to assess cardiovascular risk in elderly community-dwelling people by means of a multivariate Cox model. In 298 people older than 75 years (120 men and 178 women, average age: 79.6 years), brachial-ankle pulse wave velocity (baPWV) was measured between the right arm and ankle in a supine position. The LILAC study started on July 25, 2000, consultation was repeated yearly, and the last follow-up ended on November 30, 2004. During this follow-up span of 1227 days, there were nine cardiovascular deaths, the cause of death being myocardial infarction for two men and three women or stroke for two men and two women. In Cox proportional hazard models, baPWV as well as age, Mini-Mental State Examination (MMSE), Hasegawa Dementia Scale Revised (HDSR) and the low-frequency/high-frequency (LF/HF) ratio showed a statistically significant association with the occurrence of cardiovascular death. A two-point increase in MMSE and HDSR score significantly protected against cardiovascular death, the relative risk (RR) being 0.776 (P = 0.0369) and 0.753 (P = 0.0029), respectively. The LF/HF ratio also was significant (P = 0.025), but the other indices of HRV were not. After adjustment for age and HDSR, a 200 cm/s increase in baPWV was associated with a 30.2% increase in risk (RR = 1.302, 95% CI: 1.110-1.525), and a 500 cm/s increase in baPWV with a 93.3% increase in risk (RR = 1.933, 95% CI: 1.300-2.874, P = 0.0011), whereas the LF/HF ratio was no longer associated with a statistically significant increase in cardiovascular mortality. In elderly community-dwelling people, arterial stiffness measured by means of baPWV predicted the occurrence of cardiovascular death beyond the prediction provided by age, gender, blood pressure and cognitive functions. baPWV should be added to the cardiovascular assessment in various clinical settings, including field medical surveys and preventive screening. The early detection of risk by chronomics allows the timely institution of prophylactic measures, thereby shifting the focus from rehabilitation to prehabilitation medicine, as a public service to several Japanese towns.

Fractal analysis of heart rate variability and mortality in elderly community-dwelling people -- Longitudinal Investigation for the Longevity and Aging in Hokkaido County (LILAC) study.

AIM: Fractal analysis of heart rate (HR) variability (HRV) has been used as a new approach to evaluate the risk of mortality in various patient groups. Aim of this study is to examine the prognostic power of detrended fluctuation analysis (DFA) and traditional time- and frequency-domain analyses of HR dynamics as predictors of mortality among elderly people in a community. METHODS: We examined 298 people older than 75 years (average age: 79.6 years) and 1-h ambulatory ECG was monitored. During the last 10 min, deep respiration (6-s expiration and 4-s inspiration) was repeated six times in a supine position. Time-domain and frequency-domain measures were determined by the maximum entropy method. Scaling exponents of short-term (<11 beats, alpha 1) and longer-term (>11 beats, alpha 2) were determined by the DFA method. Six estimates, obtained from 10-min segments, were averaged to derive mean values for the entire recording span. These average values were denoted Alpha 1 and Alpha 2, estimates obtained during the first 10-min segment Alpha 1 S and Alpha 2 S, and those during the last 10-min segment Alpha 1E and Alpha 2E, respectively. The LILAC study started on July 25, 2000 and ended on November 30, 2004. We used Cox regression analysis to calculate relative risk (RR) and 95% confidence interval (CI) for all-cause mortality. Significance was considered at a value of P < 0.05. RESULTS: Gender, age and Alpha 2E showed a statistically significant association with all-cause mortality. In univariate analyses, gender was significantly associated with all-cause mortality, being associated with a RR of 3.59 (P = 0.00136). Age also significantly predicted all-cause mortality and a 5-year increase in age was associated with a RR of 1.49 (P = 0.01809). The RR of developing all-cause mortality predicted by a 0.2-unit increase in Alpha 2E was 0.58 (P = 0.00390). Other indices of fractal analysis of HRV did not have predictive value. In multivariate analyses, when both Alpha 2E and gender were used as continuous variables in the same model, Alpha 2E remained significantly associated with the occurrence of all-cause mortality (P = 0.02999). After adjustment for both gender and age, a 0.2-unit increase in Alpha 2E was associated with a RR of 0.61 (95% CI: 0.42-0.90, p = 0.01151). CONCLUSION: An intermediate-term fractal-like scaling exponent of RR intervals was a better predictor of death than the traditional measures of HR variability in elderly community-dwelling people. It is noteworthy that the longer-term (alpha 2) rather than the short-term fractal component (alpha 1) showed predictive value for all-cause mortality, which suggests that an increase in the randomness of intermediate-term HR behavior may be a specific marker of neurohumoral and sympathetic activation and therefore may also be associated with an increased risk of mortality.

Common carotid intima-media thickness is predictive of all-cause and cardiovascular mortality in elderly community-dwelling people: Longitudinal Investigation for the Longevity and Aging in Hokkaido County (LILAC) study.

Several cohort studies have examined the association of carotid intima-media thickness (IMT) with the risk of stroke or myocardial infarction in apparently healthy persons. We investigated the predictive value of IMT of cardiovascular mortality in elderly community-dwelling people, beyond the prediction provided by age and MMSE, assessed by means of a multivariate Cox model. Carotid IMT and plaque were evaluated bilaterally with ultrasonography in 298 people older than 75 years (120 men and 178 women, average age: 79.6 years). The LILAC study started on July 25, 2000. Consultations were repeated every year. The follow-up ended on November 30, 2004. During the mean follow-up span of 1152 days, 30 subjects (21 men and nine women) died. Nine deaths were attributable to cardiovascular causes (myocardial infarction: two men and three women; stroke: two men and two women). The age- and MMSE-adjusted relative risk (RR) and 95% confidence interval (95% CI) of developing all-cause mortality was assessed. A 0.3 mm increase in left IMT was associated with a RR of predicted 1.647 (1.075-2.524), and a similar increase in right IMT with a RR of 3.327 (1.429-7.746). For cardiovascular mortality, the corresponding RR values were 2.351 (1.029-5.372) and 2.890 (1.059-7.891), respectively. Carotid IMT assessed by ultrasonography is positively associated with an increased risk of all-cause and cardiovascular death in elderly community-dwelling people.

Physical mapping of the genome and sequence analysis at the inverted terminal repetition of adenovirus type 4 DNA.

The genome of adenovirus type 4 (Ad4), the unique member of Ad group E, has been mapped with nine restriction endonucleases. Comparison of the occurrence of restriction endonuclease cleavage sites on Ad2, Ad7, Ad12 and Ad4 indicates that there is very little homology between these serotypes. Sequence analysis at the ITR of Ad4 showed that the "CAT" box which is present in all the ITRs of Ad's so far sequenced is absent in Ad4. The length of 116 bp for the ITR of Ad4 is also different from that of other Ad subgroups.

The nucleotide sequence of the right-hand terminal SmaI-K fragment of adenovirus type 2 DNA.

The primary structure of the SmaI-K fragment of adenovirus type 2 (Ad2) DNA has been determined. This region includes one of the origins of DNA replication (Winnacker, 1978; Sussenbach and Kuijk, 1978). A leader sequence for an early mRNA in region 4 (Berk and Sharp, 1977; 1978) has also been mapped in this region. The comparison of the primary structure of this region in Ad2 DNA with the corresponding region in Ad5 DNA shows a remarkable homology which may be significant in view of the fact that Ad2 and Ad5 DNAs can interchangeably function in the in vitro replication system of Challberg and Kelly (1979).

Primary structure of bovine lactate dehydrogenase-A isozyme and its synthesis in Escherichia coli.

Eleven cDNA clones encoding lactate dehydrogenase(LDH)-A isozyme were isolated from a bovine lymphocyte cDNA library, and the nucleotide sequences of three of the clones (pLDH5, pLDH9 and pLDH12) were determined. With the exception of variation in the 5' portion, two cDNA clones (pLDH9 and pLDH12) appeared to contain the full-length cDNA of 1786 bp, consisting of the protein-coding sequence (996 bp), the 5'- and the 3'-untranslated regions and the poly(dA) tail. The predicted amino acid (aa) sequence of bovine LDH-A (332 aa) showed 96.7% homology with that of pig LDH-A. The protein-coding cDNA region (1650 bp) was inserted into an Escherichia coli expression vector ptac11 and expressed. The protein synthesized in E. coli showed enzyme activity of LDH and was identified by cellogel electrophoresis as LDH-5 isozyme whose subunit M chain is the product of the LDH-A gene.

Characterization of the sheep apolipoprotein E (ApoE) gene and allelic variations of the ApoE gene in scrapie Suffolk sheep.

Apolipoprotein E (ApoE) plays a central role in lipid transport and is suggested to be involved in neuronal repair. Human ApoE epsilon 4 allele is known as a risk factor for Alzheimer's disease, and an association of the human ApoE genotype with the human prion disease, Creutzfeldt-Jakob disease, is suggested, albeit controversial. We analyzed the sheep ApoE gene to determine whether any association between the sheep ApoE genotype and the sheep prion disease, scrapie, existed. The sheep ApoE cDNA contained an open reading frame (ORF) consisting of 948 base pairs (bp) that encoded 316 amino acids (aa). The sheep ApoE gene was composed of four exons separated by three introns, and the ORF was encoded by three exons, designated exons 2, 3, and 4. Nucleotide sequence analysis also showed the presence of one G/T nucleotide polymorphism in the ORF that resulted in an Ala/Ser amino-acid substitution at codon 258. PCR-restriction fragment length polymorphism analysis of genomic DNA showed the presence of three sheep ApoE genotypes that were the result of the homologous and heterologous combinations of the two alleles. We analyzed the sheep ApoE genotypic and the allelic frequencies in scrapie and control Suffolk sheep, but they did not significantly differ from those in the control sheep, even though PrP genotype-matched populations were compared. The ApoE genotype appeared not to be associated with the progression of the disease when looking at the age at death. These results indicated that in Suffolk sheep, none of the ApoE genotypes was associated with scrapie.

Phylogenetic relationships between adenoviruses as inferred from nucleotide sequences of inverted terminal repeats.

The nucleotide (nt) sequences of inverted terminal repeats (ITR) from human adenovirus (Ad) 19, bovine Ad1 (BAd1), bovine Ad3 (BAd3), canine Ad2 (CAd2) and an avian Ad, EDS-76, were determined. The length of the ITR sequence was 160 bp in Ad19, 159 bp in BAd1, 195 bp in BAd3, 196 bp in CAd2 and 52 bp in EDS-76. CAd2 had the longest ITR among the examined Ads, BAd3 the second longest, and EDS-76 had the shortest ITR. A TAAT sequence located between the 10th and 13th nt counted from the ends was conserved in all Ads examined so far. To determine phylogenetic relationships among human and animal Ads, sequences of their ITRs were compared, and a phylogenetic tree was constructed by using the maximum-likelihood method. It is the method involving statistical analysis of computing the probability of a particular set of sequences on a given tree and maximizing this probability over all evolutionary trees [Felsenstein, J. Mol. Evol. 17 (1981) 368-376]. From these analyses, it was found that members belonging to the same human Ad subgenus are related closely to each other, whereas representatives of different human subgenera are distributed rather divergently among animal Ads.

Morphological and biochemical evidence that scrapie-associated fibrils are derived from aggregated amyloid-like filaments.

The membrane fraction from scrapie infected mouse brains was dissolved in saturated urea, centrifuged on a 10 to 50% glycerol gradient at 35,000 rpm for 24 h, and fractionated from the bottom of the tube into 11 fractions. PrP was detected throughout the gradient. However, the relative PrP concentrations of fractions 4 and 8 were the highest. The relative PrP concentration versus protein concentration of fractions 1 to 4 was higher than that of the other fractions. Scrapie infectivity also was detected in all fractions. Fractions 2, 3, 4, 7, and 8 produced the shortest incubation periods. Positively stained filamentous aggregates with sizes varying from about 40 x 60 nm to more than 4 microns were observed in fractions 2 and 4 by negative staining. These resembled amyloid filaments. Congo red-stained aggregates showed birefringence under polarized light. Aggregation of the filamentous aggregates was observed by incubation with anti-mouse SAF serum. Fine fibrils 10-18 nm in width were partially dissociated from the aggregates by brief exposure to the detergent Sarkosyl. These facts suggest that SAF are not products of self-assembly from subunit structures liberated from membranes by exposure to detergent, but exist as aggregates of amyloid-like filaments from which SAF are dissociated by detergent extraction.

Biological activity of subfractions from scrapie-associated fibrils.

Subfractions, a nucleic acid fraction and a PrP fraction consisting of PrP17-25, a core fragment of PrPsc, were prepared from the scrapie-associated fibril-enriched fraction from scapie-affected mouse brains. The nucleic acid fraction consisted mainly of variously fragmented DNA and no scrapie-specific nucleic acid was detected in the fraction by SDS polyacrylamide gel electrophoresis. To examine the biological activity, the nucleic acid fraction was either first introduced into mouse L-929 cells before or after nuclease treatments, then transfected cell lysates prepared 2 weeks later were inoculated into mice, or directly inoculated into mice with or without the PrP fraction. The PrP fraction alone was also inoculated into mice. Mice inoculated with the transfected cell lysates or with the nucleic acid fraction alone showed no scrapie signs during their lifespan or the observation period. While 60% of the mice inoculated with the PrP fraction alone and 67% of those inoculated with the fraction together with the nucleic acid fraction showed clinical signs of scrapie. A nucleic acid molecule bound covalently to PrP17-25 was not detected. The results obtained by the present procedures so far suggest scrapie infectivity to be associated with PrPsc, which does not contain any detectable scrapie-genome molecule as either free or covalently bound nucleic acid.

Cloning and nucleotide sequence of the gene (citA) encoding a citrate carrier from Salmonella typhimurium.

A cryptic citrate transport gene (citA) from Salmonella typhimurium chromosome was cloned and its nucleotide sequence was determined. The cloned plasmid conferred citrate-utilizing ability on wild-type Escherichia coli, which cannot grow on citrate as the sole source of carbon. The resultant E. coli transformant was able to transport citrate. A 1,302-base-pair open reading frame with a preceding ribosomal binding site was found in the cloned DNA fragment. The 434-amino-acid protein that could be translated from this open reading frame is highly hydrophobic (69% nonpolar amino acid residues), consistent with the fact that the transport protein is an intrinsic membrane protein. The molecular weight of this protein was calculated to be 47,188. The gene sequence determined is highly homologous to those of Cit+ plasmid-mediated citrate transport gene, citA, from E. coli, the chromosomal citA gene from Citrobacter amalonaticus and the chromosomal cit+ gene from Klebsiella pneumoniae. The hydropathy profile of the deduced amino acid sequence suggests that this carrier has 12 hydrophobic segments, which may span the membrane lipid bilayer.

Sensitive enzyme-linked immunosorbent assay for detection of PrP(Sc) in crude tissue extracts from scrapie-affected mice.

An enzyme-linked immunosorbent assay (ELISA) was developed that detects PrP(Sc) in crude extracts from brain and spleen tissue of scrapie-affected mice with high sensitivity and specificity. Brain tissue was homogenized in 8% Zwittergent 3-12 and 0.5% Sarkosyl. The homogenate was treated with collagenase and DNase I and then subjected to proteinase K digestion. Precipitates containing PrP(Sc) were obtained by ultracentrifugation. Spleen tissue was homogenized in 4% Triton X-100 and 0.5% Sarkosyl, and the homogenate was treated firstly with collagenase and DNase I, and secondly with proteinase K. PrP(Sc) was then extracted with 6.25% Sarkosyl and precipitated through salting-out with NaCl and by ultracentrifugation. When PrP(Sc) was dissolved in 3-4 M guanidine thiocyanate and adsorbed to microtiter plates, strong and specific reactions to the formation of antigen-antibody complexes could be detected by ELISA. The sensitivity of PrP(Sc)-detection for this ELISA, as measured by serial dilution of scrapie material in tissue homogenates from uninfected animals, was equal or higher than that attained by Western blot. This ELISA is more rapid than Western blot and seems to be more suitable for screening large numbers of animals. It also has potential application for the diagnosis of the transmissible spongiform encephalopathies.

Photoinactivation of virus infectivity by hypocrellin A.

We investigated the photoinactivation of virus infectivity by hypocrellin A and its mechanism. The titers of vesicular stomatitis virus (VSV) and human immunodeficiency virus type 1 (HIV-1), both of which are enveloped viruses, were reduced upon illumination with hypocrellin A in a concentration-dependent manner, whereas canine parvovirus, a nonenveloped virus, was not killed. The removal of oxygen or addition of sodium azide or beta-carotene both inhibited VSV inactivation. Mannitol and superoxide dismutase had no effect on VSV inactivation. These results indicate that singlet oxygen was involved in the process of VSV inactivation. Of the three major VSV membrane proteins, peripheral membrane protein M was most damaged by the hypocrellin A phototreatment.

Impact of circadian amplitude and chronotherapy: relevance to prevention and treatment of stroke.

The long-acting calcium antagonist nifedipine reduces the incidence of stroke in Eastern Asia, as shown by the Shanghai Trial Of Nifedipine in the Elderly (STONE) and the Systolic Hypertension in China (Syst-China) trials. Recent trials in Japan have shown that benidipine may be more efficient than the former drug in preventing strokes in the elderly. Benidipine, commonly prescribed in Japan for a definite depressor effect, reportedly without causing remarkable fluctuations in blood pressure (BP), is investigated herein from a chronobiological viewpoint. Eighteen subjects (nine women and nine men, 39 to 87 years of age) with essential hypertension (office and ambulatory systolic, S/diastolic, D BP values above 160/95 mm Hg and 130/80 mm Hg, respectively) were enrolled in this investigation. Ambulatory BP was monitored at 30-min intervals for at least 24 h (ABPM-630, Colin Medical) before and after 4 weeks of crossover treatment with nifedipine tablets (twice daily, 20 mg/d) and benidipine (once daily, 4 mg/d, in the morning). The results indicate that: 1) benidipine and nifedipine reduce 24-h daytime (10:00-20:00) and nighttime (00:00-06:00) averages of SBP and DBP (P < 0.001); 2) the circadian double amplitude of BP is decreased after treatment with benidipine (from 28.6 to 21.1 mm Hg SBP and from 19.7 to 15.2 mm Hg DBP; P< 0.05), while the day-night difference in SBP is increased after treatment with nifedipine (18.6 vs 27.9 mm Hg, P< 0.01); and 3) the increase in the day-night difference of heart rate (HR) is significant after treatment with benidipine (13.6 vs 18.8 beats per minute, bpm; P< 0.05), but not with nifedipine. We have previously evaluated the usefulness of the circadian amplitude of BP as a prognostic tool of cardiovascular outcome, and found that an excessive circadian SBP or DBP amplitude was associated with an increased risk of vascular disease. The fact that benidipine reduces the circadian BP amplitude may be one reason for the superiority of this treatment over nifedipine in preventing an adverse outcome. A reduced heart rate variability (HRV) also predicts adverse cardiovascular outcomes in patients with overt cardiovascular disease and in hypertensive subjects. The fact that benidipine increases the day-night difference in HR may be another reason for the positive effects of this treatment.

Intragastric acidity and circadian rhythm.

Most patients with peptic ulcers or gastroesophageal reflex disease develop subjective symptoms of epigastralgia and retrosternal pain during the period of time from the middle of the night to the early dawn (nocturnal pain). Such pain often disappears before breakfast. Disturbed circadian rhythm of gastric acid secretion may have a close relationship with the onset and aggravation of acid-related diseases. On the other hand, Helicobacter pylori has been considered to be an etiological agent of duodenal ulcer, and H. pylori eradication has been conducted in patients with gastritis and peptic ulcers. However, such eradication therapy sometimes results in the onset or deterioration of gastroesophageal reflux diseases. In this context, the question of whether the circadian rhythm of gastric acid secretion varies in accordance with the presence or absence of H. pylori infection is of interest. In the present study, we examined the fluctuation in intragastric acidity via a portable pH meter in 10 H. pylori-positive and 10 H. pylori-negative subjects. As a result, a significant difference in the circadian rhythmicity was observed between the H. pylori-negative and the H. pylori-positive group, with mean values for each parameter of 28.1 and 13.3 for amplitude, 22.7 and 12.4 for the midline-estimating statistic of rhythm (MESOR), and 324.0 and 321.0 for acrophase, respectively (P < 0.001). In both H. pylori-positive and negative groups, a tendency was observed toward an increase in intragastric acidity during the time period from the middle of the night to the early dawn, and toward a decrease in intragastric acidity during the early morning. In the H. pylori-positive group, the values for intragastric acidity over time were lower, and the degree of amplitude was smaller as compared to the H. pylori-negative group. Further, H. pylori-positive individuals were at a more advanced stage of the disease.

Effect of H2 blockers on the circadian rhythm of intragastric acidity.

Most patients with peptic ulcer or gastro-oesophageal reflux disease develop nocturnal pain (epigastric and retrosternal pain from midnight to early morning), which often disappears before breakfast. Such pain may be related to a disturbance of the circadian rhythm of gastric acid secretion. Helicobacter pylori is a known aetiological agent of peptic ulcer disease and patients with gastritis or ulcers now undergo infection eradication therapy. However, this can result in the onset or exacerbation of gastro-oesophageal reflux disease. There has been a marked increase in the number of patients with oesophagitis rather than peptic ulcer and because most are negative for H. pylori, attention has centred on the status of their gastric acid secretion. Some patients with oesophagitis complain of nocturnal pain despite treatment with a proton pump inhibitor, and in those cases a short course of an H2 blocker can be very effective. We used a portable pH meter to study, in a cross-over fashion, the changes in the circadian rhythm of gastric acid secretion caused by two H2 blockers, laftidine and famotidine, in 10 H. pylori-negative subjects. There was a significant difference in the rhythm between baseline (no treatment) and when laftidine or famotidine were administered, with mean values for amplitude of 28.1, 13.80 and 10.82, respectively; for the midline estimating statistic of rhythm (MESOR), 22.7, 10.80, and 11.54; and for acrophase, 324.0. 312.3, and 274.5 (p < 0.001). The H2 blockers suppressed the normal circadian rhythm of intragastric acidity, which rises in the evening until the middle of the night and then drops in the morning.

Geomagnetic disturbance associated with decrease in heart rate variability in a subarctic area.

BACKGROUND: Physical environmental variables, such as the natural variation in the geomagnetic field in and around the earth, influence biological processes and human health. The effect of geomagnetic disturbances on heart rate variability (HRV) in healthy students in a subarctic area is studied herein. SUBJECTS AND METHODS: Seven-day records by Holter ECG were obtained from eight clinically healthy subjects in Alta, Norway (70 N). Frequency- and time-domain measures of HRV were compared between 24-hour spans of high geomagnetic disturbance versus quiet conditions. RESULTS: A 5.9% increase in the 24-hour average of HR (P = 0.020) and a 25.2% decrease in HRV (P = 0.002) were documented on days of high geomagnetic disturbance. The decrease in spectral power was found primarily at frequencies lower than 0.04 Hz and was not statistically significant around 3.6 sec. CONCLUSIONS: The physiological mechanism involved may be other than the parasympathetic, usually identified with spectral power centered around 3.6 sec, a spectral region wherein no statistically significant differences were found.