Sleep-Disordered Breathing in Patients With Idiopathic Cardiomyopathy

BACKGROUND

Sleep-disordered breathing may adversely affect heart function, and thereby contribute to the progression of heart failure. A study was undertaken in patients with idiopathic cardiomyopathy to document the characteristics of sleep-disordered breathing.

METHODS AND RESULTS

Thirty-five patients with a diagnosis of idiopathic cardiomyopathy, comprising 20 patients with dilated cardiomyopathy (DCM) and 15 patients with hypertrophic cardiomyopathy (HCM), underwent overnight polysomnography. Of these 35, 16 (80%) of the DCM patients and 7 (47%) of the HCM patients had sleep-disordered breathing. Central sleep apnea-hypopnea syndrome (CSAHS) was seen in 10 DCM patients, but not in the HCM patients, and obstructive sleep apnea-hypopnea syndrome (OSAHS) was seen in 6 DCM patients and 7 HCM patients. CSAHS was seen in DCM patients with a low left ventricular ejection fraction. HCM patients with OSAHS had a significantly greater body mass index (BMI) than those without OSAHS and CSAHS (27.6 +/- 3.8 vs 22.0 +/- 4.0 kg/m2, p<0.05). DCM patients with OSAHS had a larger BMI than those with CSAHS (29.3 +/- 5.8 vs 24.2 +/- 4.0 kg/m2, p<0.05) and those without OSAHS and CSAHS (29.3 +/- 5.8 vs 21.3 +/- 3.1 kg/m2, p<0.05).

CONCLUSIONS

Sleep-disordered breathing is common in patients with idiopathic cardiomyopathy; half of DCM patients had CSAHS, which was closely associated with obesity.

Pulmonary hypertension in patients with severe obstructive sleep apnea

Thirty-seven patients (35 men and two women) with obstructive sleep apnea-hypopnea syndrome (OSAHS) without any known cardiovascular and lung diseases were examined by Doppler echocardiography. Eight of the 37 (21.6%) patients experienced daytime pulmonary hypertension (PH), and all of them had severe OSAHS with an apnea-hypopnea index of > 30. The study suggested that one-third of patients with severe OSAHS had daytime PH.

Falling asleep while driving and automobile accidents among patients with obstructive sleep apnea-hypopnea syndrome

Among 448 patients with obstructive sleep apnea-hypopnea syndrome (OSAHS), 40 patients (8.9%) had been involved in one or more automobile accidents during the preceding 5 years. The main cause of these accidents was falling asleep while driving. Excessive sleepiness during driving was associated with an Epworth sleepiness scale (ESS) score of > 11 and/or an apnea-hypopnea index (AHI) of > 15. The automobile accident rate among 182 patients with severe OSAHS (AHI > 30) was significantly higher than the rate among 106 simple snorers (AHI < 5). Although four of the simple snorers were involved in automobile accidents, their ESS scores were all very high (15 or more).

Increase in pulse pressure relates to diabetes mellitus and low HDL cholesterol, but not to hyperlipidemia in hypertensive patients aged 50 years or older

Higher pulse pressure is associated with higher cardiovascular risk. We investigated the relationship between pulse pressure and known metabolic risk factors in hypertensive patients who had not experienced stroke or myocardial infarction. In a multicenter cross-sectional survey made in 1995, we registered 939 hypertensive patients aged > or = 50 years. Of these, 734 had never experienced stroke or myocardial infarction. We divided these 734 patients into two groups based on the value of their pulse pressures: 396 patients with a pulse pressure > or = 60 mmHg, and 338 patients with a pulse pressure<60 mmHg. The average pulse pressure value was 72 +/- 12 mmHg in the former group, and 49 +/- 8 mmHg in the latter group. The former group exhibited advanced age, a higher women-to-men ratio, lower high-density lipoprotein (HDL) cholesterol, and higher systolic and lower diastolic blood pressure. Diabetes mellitus (DM) and left ventricular hypertrophy were more frequently noticed in the former group than in the latter group. The prevalence of hyperlipidemia, however, was similar in the two groups. The association of pulse pressure with DM and low HDL cholesterol was statistically significant by multiple logistic analysis adjusted for age, sex, and other known cardiovascular risk factors. In conclusion, pulse pressure increases with advancing age. DM made a substantially larger contribution to the increase in pulse pressure than hyperlipidemia.

Development of a gamma ray monitor using a CdZnTe semiconductor detector

The aim of this study was to develop a new X ray and gamma ray monitor using the CdZnTe semiconductor detector, which has high sensitivity at room temperature. The pulse height spectra and the detection efficiencies of a 10 mm x 10 mm by 2 mm thick CdZnTe detector were measured in the energy range of 10 keV to 1.8 MeV by using monoenergetic X ray and gamma ray sources. The measured results showed very good agreement with the results calculated using the EGS4 Monte Carlo code taking into account the charge collection efficiency in the detector. By using two CZT detectors of 10 mm x 10 mm x 2 mm and 3 mm x 3 mm x 2 mm coupled with a filter, the weighted sum of a few energy channels with different cut-off energies was finally found to achieve a flat energy response with an equivalent dose (counts per microSv) within +/-30% or +/- 10% deviation.

Disruption of Xpg increases spontaneous mutation frequency, particularly A:T to C:G transversion

Cells isolated from Xpg (the mouse counterpart of XPG)-disrupted mice underwent premature senescence and showed early onset of immortalization, suggesting that Xpg might be involved in genetic stability. Recent studies showed that human XPG, in addition to its function in the nucleotide excision repair (NER), was involved in the repair of oxidative base damages such as thymine glycol (Tg) and 8-oxo-guanine (8-oxoG), and this may explain the genetic instability observed in Xpg-deficient cells. To clarify this point, we determined spontaneous mutation frequencies and the type of spontaneous base substitution mutations in cells obtained from normal and Xpg-deficient mice using the supF shuttle vector (pNY200) for mutation assay. The spontaneous mutation frequency of the supF gene in pNY200 propagated in the Xpg-deficient cells was about three times higher than that in normal cells, indicating the importance of Xpg in reducing the frequency of spontaneous mutations. The frequency of spontaneous base substitution mutations at A:T sites, particularly that of the A:T to C:G transversion, increased markedly in the Xpg-deficient cells.

8-oxo-dGTPase, which prevents oxidative stress-induced DNA damage, increases in the mitochondria from failing hearts

BACKGROUND

Reactive oxygen species (ROS) can cause an oxidative modification of nucleotides, such as 8-oxo-7,8-dihydrodeoxyguanosine triphosphate (8-oxo-dGTP), which can lead to defects in DNA replication. The misincorporation of 8-oxo-dGTP into DNA is prevented by 8-oxo-dGTPase, which hydrolyzes 8-oxo-dGTP into 8-oxo-dGMP. The changes in this defensive system have not yet been examined in failing hearts, in which the generation of ROS increases.

METHODS AND RESULTS

Myocardial infarction (MI) was created in mice by ligating the left coronary artery. Four weeks later, the left ventricle was dilated and contractility was diminished on echocardiography. The generation of ROS, as measured by electron spin resonance spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, increased in the noninfarcted left ventricle from MI mice. The formation of thiobarbituric acid-reactive substances also increased in the mitochondria from MI mice. 8-Oxo-dGTPase was detected in the mitochondrial fractions isolated from MI mice using a Western blot analysis with an antibody to its human homologue (hMTH1). Immunohistochemistry showed positive staining for hMTH1 was localized in the cardiac myocytes.

CONCLUSIONS

The level of 8-oxo-dGTPase increased in the mitochondria isolated from post-MI hearts as oxidative stress increased, thus suggesting that a preventive mechanism is activated against ROS-induced DNA damage. As a result, 8-oxo-dGTPase is considered a useful marker of mitochondrial oxidative stress in heart failure.

Differential expression of CCR3 ligand mRNA in guinea pig lungs during allergen-induced inflammation

OBJECTIVE AND DESIGN

The gene expression profile of CCR3 ligands, eotaxin, RANTES, and monocyte chemoattractant protein-3 (MCP-3), was examined in normal and inflamed guinea pig lungs.

MATERIAL

Male Hartley guinea pigs (n = 49).

METHODS

Pulmonary mRNA was obtained from naive animals, animals treated with intravenous lipopolysaccharide administration, and animals repeatedly exposed to aerosolized allergen (ovalbumin). Northern analysis was performed to quantify pulmonary expression of eotaxin, RANTES, and MCP-3 mRNA. Pulmonary eosinophil peroxidase (EPO) activity was measured to quantify eosinophil accumulation.

RESULTS

Eotaxin and RANTES mRNAs, but not MCP-3 mRNA, were constitutively expressed in guinea pig lungs. Lipopolysaccharide treatment increased MCP-3 mRNA expression, but not eotaxin or RANTES mRNA. In contrast, allergen exposure in sensitized animals caused an increase in eotaxin mRNA, which demonstrated good temporal and quantitative correlation with pulmonary EPO activity, but not in MCP-3 or RANTES mRNA.

CONCLUSIONS

Guinea pig CCR3 ligands demonstrated different gene expression profiles in normal and inflamed airways, suggesting that they play different physiological and pathophysiological roles in the airway.

Single nucleotide polymorphism of human platelet-activating factor receptor impairs G-protein activation

Various proinflammatory and vasoactive actions of platelet-activating factor (PAF) are mediated through a specific G-protein-coupled PAF receptor (PAFR). We identified a novel DNA variant in the human PAFR gene, which substitutes an aspartic acid for an alanine residue at position 224 (A224D) in the putative third cytoplasmic loop. This mutation was observed in a Japanese population at an allele frequency of 7.8%. To delineate the functional consequences of this structural alteration, Chinese hamster ovary cells were stably transfected with constructs encoding either wild-type or A224D mutated PAFR. No significant difference was observed in the expression level of the receptor or the affinity to PAF or to an antagonist, WEB2086, between the cells transfected with wild-type and mutant PAFR. Chinese hamster ovary cells expressing A224D mutant PAFR displayed partial but significant reduction of PAF-induced intracellular signals such as calcium mobilization, inositol phosphate production, inhibition of adenylyl cyclase, and chemotaxis. These findings suggest that this variant receptor produced by a naturally occurring mutation exhibits impaired coupling to G-proteins and may be a basis for interindividual variation in PAF-related physiological responses, disease predisposition or phenotypes, and drug responsiveness.

Isolation and Characterization of Derivative Lines of the Onion Yellows Phytoplasma that Do Not Cause Stunting or Phloem Hyperplasia

ABSTRACT Two lines of onion yellows phytoplasma producing milder symptoms were isolated from the original line (OY-W). One has an additional characteristic, non-insect-transmissibility (OY-NIM), compared with the other (OY-M). OY-M was established after maintaining OY-W for 11 years on a plant host (Chrysanthemum coronarium) with an insect vector (Macrosteles striifrons), and OY-NIM was isolated after subsequent maintenance of OY-M in plants by periodic grafting. Polymerase chain analysis suggested that OY-NIM cannot traverse the gut or survive in the hemolymph of the leafhopper. OY-W results in witches'-broom formation and stunted growth in the host plant. In contrast, OY-M and OY-NIM do not cause stunting in the host plant, although they result in witches'-broom. Histopathological analysis of these lines revealed that the hyperplastic phloem tissue and severe phloem necrosis seen in OY-W did not exist in OY-M and OY-NIM. This was attributed to a reduction in the population of phytoplasma in tissues in both OY-M- and OY-NIM-infected plants. The results suggest that the cause of stunting and phloem hyperplasia may be genetically different from the cause of witches'-broom. Pulsed field gel electrophoresis analysis showed that OY-M had a smaller genome size ( approximately 870 kbp) than OY-W ( approximately 1,000 kbp). Thus, some of the OY-W genes responsible for pathogenicity may not be present in OY-M.

Expression and chromosome location of hamster Ku70 and Ku80

Ku proteins play an important role in DNA double-strand break (DSB) repair, chromosome maintenance, and growth regulation. To understand the fundamental characteristics of Ku proteins, we examined the electrophoretic mobility and expression of hamster Ku70 and Ku80 and determined the chromosome locations of their genes. The electrophoretic mobility of hamster Ku proteins are different from that of human Ku proteins. No significant changes in the quantity of Ku proteins were observed in CHO-K1 cells treated with 10 Gy of ionizing radiation, suggesting that both proteins are expressed constitutively in amounts adequate to repair DNA DSBs. The chromosome locations of the Ku genes were determined by direct R-banding fluorescence in situ hybridization. The Ku70 gene was localized to Syrian hamster chromosome 4qa4.1--> qa4.2 and Chinese hamster chromosome 2p3.1, and the Ku80 gene was localized to Syrian hamster chromosome 4qb5--> qb6.1 and Chinese hamster chromosome 2p3.5-->p3.6. These results provide clues to the biological functions of Ku, as well as useful information for constructing comparative chromosome maps between hamsters and other mammalian species, including human, mouse, and rat.

Enhanced generation of reactive oxygen species in the limb skeletal muscles from a murine infarct model of heart failure

BACKGROUND

The generation of reactive oxygen species (ROS) is enhanced in the failing myocardium. We hypothesized that ROS were also increased in the limb skeletal muscles in heart failure. Methods and Results-- Myocardial infarction (MI) was created in mice by ligating the left coronary artery. After 4 weeks, the left ventricle was dilated and contractility was diminished by echocardiography. Left ventricular end-diastolic pressure was elevated after MI in association with an increase in lung weight/body weight and the presence of pleural effusion. The generation of ROS in the limb muscles, including the soleus and gastrocnemius muscles, which were excised after MI, was measured by electron spin resonance spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (hydroxy-TEMPO). Overall, generation was increased, but it was attenuated in the presence of dimethylthiourea or 4,5-dihydroxy-1,2-benzenedisulfonic disodium salt in the reaction mixture, indicating increased generation of hydroxyl radicals originating from superoxide anion. Thiobarbituric acid-reactive substance formation was also increased in muscles after MI. Mitochondrial complex I and III activities were both decreased after MI, which may have caused the functional uncoupling of the respiratory chain and ROS production. Antioxidant enzyme activities, including superoxide dismutase, catalase, and glutathione peroxidase, were comparable between groups.

CONCLUSIONS

Skeletal muscle in post-MI heart failure expressed an increased amount of ROS in association with ROS-mediated lipid peroxidation. This supports the hypothesis that oxidative stress may cause (at least in part) skeletal muscle dysfunction in heart failure.

Narcolepsy and other non-SAS hypersomnia in sleep breathing disorders clinic

Four of the 708 snorers (0.56%), referred to our sleep breathing disorders clinic for the past 2 years were diagnosed as having narcolepsy-cataplexy. Detecting HLA DRB1*1501/DQB1*0602 positive was informative for differentiating genuine narcolepsy from non-sleep apnea syndrome (non-SAS) hypersomnia in our clinic. A non-SAS obese boy, diagnosed as having essential hypersomnia syndrome, was found to be HLA DRB1*1502/DQB1*0601 positive. His hypocretin concentration was 206 pg/mL in the cerebrospinal fluid.

Effects of physiological cardiac pacing on sleep-disordered breathing in patients with chronic bradydysrhythmias

In six patients with chronic bradydysrhythmias, polysomnographies were performed before cardiac pacemaker implantation and over the week following implantation. A patient with third-degree atrioventricular block (AVB) and two patients with sinus node dysfunction (SND) were associated with sleep-disordered breathing (SDB). Their cardiac pacemaker therapies, with the increase in the average heart rate, led to a reduction of apnea-hypopnea index and/or an improvement of Cheyne-Stokes breathing. It seems that chronic bradydysrhythmia is one of the causative factors leading to SDB.

Purkinje cell degeneration in mice lacking the xeroderma pigmentosum group G gene

Laboratory mice carrying the nonfunctional xeroderma pigmentosum group G gene (the mouse counterpart of the human XPG gene) alleles have been generated by using gene-targeting and embryonic stem cell technology. Homozygote animals of this autosomal recessive disease exhibited signs and symptoms, such as postnatal growth retardation, reduced levels of activity, progressive ataxia and premature death, similar to the clinical manifestations of Cockayne syndrome (CS). Histological analysis of the cerebellum revealed multiple pyknotic cells in the Purkinje cell layer of the xpg homozygotes, which had atrophic cell bodies and shrunken nuclei. Further examination by an immunohistochemistry for calbindin-D 28k (CaBP) showed that a large number of immunoreactive Purkinje cells were atrophic and their dendritic trees were smaller and shorter than in wild-type littermates. These results indicated a marked degeneration of Purkinje cells in the xpg mutant cerebellum. Study by in situ detection of DNA fragmentation in the cerebellar cortex demonstrated that some deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin in situ nick labeling (TUNEL)-positive cells appeared in the granule layer of the mutant mice, but few cell deaths were confirmed in the Purkinje layer. These results suggested Purkinje cell degeneration in the mutant cerebellum was underway, in which much Purkinje cell death had not appeared, and the appearance of some abnormal cerebellar symptoms in the xpg-deficient mice was not only due to a marked Purkinje cell degeneration, but also to damage of other cells.