Fumio Kurogouchi

A case of mitochondrial cytopathy with a typical point mutation for MELAS, presenting with Severe focal-segmental glomerulosclerosis as main clinical manifestation

A 27-year-old female with short stature and mild hearing loss was diagnosed as having focal-segmental glomerulosclerosis by renal biopsy at our hospital. One year later she developed progressive renal dysfunction and cardiac failure and was admitted again to our hospital for evaluation. Though her only neurological disorder was mild hearing loss, her short stature and elevated lactate and pyruvate values in cerebrospinal fluid suggested mitochondrial cytopathy. A muscle biopsy specimen of the left biceps brachii, using modified Gomori trichrome stain, showed a typical image of ragged-red fibers, and an increased number of giant mitochondria with paracrystalline inclusions were visible by electron microscopy. Mitochondrial DNA from the skeletal muscle showed an A-to-G transition at 3243 of transfer RNALeu(UUR), the common point mutation for mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes. These data confirmed the diagnosis of atypical mitochondrial cytopathy with renal and heart involvement. Mitochondrial cytopathies are often associated with hypertrophic cardiomyopathy but rarely with renal disease. Among the few reported cases with associated renal disease, most included renal tubular disorders; few cases with focal glomerular sclerosis are known. The present case of atypical mitochondrial cytopathy was characterized by a unique clinical course and rare complications with focal-segmental glomerulosclerosis.

Autonomic control of the location and rate of the cardiac pacemaker in the sinoatrial fat pad of parasympathetically denervated dog hearts.

Autonomic Regulation of Pacemaker Sites. Introduction: Parasympathetic activity predominates over sympathetic activity not only with respect to heart rate but also with respect to the pacemaker location in the dog heart. After we removed the parasympathetic neural elements in the sinoatrial (SA) fat pad in the right atrium, we observed that cervical vagus stimulation did not decrease the atrial rate, but it did suppress the increase in rate evoked by sympathetic stimulation. We determined whether the pacemaker rate and location were affected by presynaptic or postsynaptic mechanisms.

Heterogeneous Distribution Of β-Adrenoceptors and Muscarinic Receptors In The Sinoatrial Node And Right Atrium Of The Dog

1. The pacemaker site is known to shift away from the sinoatrial (SA) node in response to autonomic stimuli.

Parasympathetic Inhibition of Sympathetic Effects on Pacemaker Location and Rate in Hearts of Anesthetized Dogs

Autonomic Effect on Pacemaker Location. introduction: The site of impulse origin in the right atrium generally is considered to be a single static locus within the sinoatrial (SA) node. Previous investigators showed that the pacemaker site may shift due to changes in sympathetic or parasympathetic neural activity. We investigated the interactions between sympathetic and parasympathetic influences on the site of impulse initiation in the right atrium in anesthetized dogs.

CNP causes receptor-mediated positive dromotropic effects in anesthetized dog hearts

No data are available for the direct effect of C-type natriuretic peptide (CNP) on atrioventricular (AV) conduction in mammalian hearts. Thus we studied the dromotropic effects of CNP-22 injected into the AV node artery in autonomically decentralized hearts in open-chest, anesthetized dogs. CNP decreased AV interval (AV conduction time) in a dose-dependent manner with increase in coronary artery blood flow rate in six anesthetized dogs. Isosorbide dinitrate did not affect AV interval, but it increased coronary artery blood flow rate. A guanylyl cyclase-linked natriuretic peptide receptor antagonist, HS-142-1, inhibited the decreases in AV interval and the increases in coronary blood flow rate in response to CNP, whereas propranolol did not affect the positive dromotropic response to CNP. These results demonstrate that CNP decreases AV interval and increases coronary artery blood flow rate mediated by a guanylyl cyclase-linked natriuretic peptide receptor, but not beta-adrenoceptor, in the dog heart.No data are available for the direct effect of C-type natriuretic peptide (CNP) on atrioventricular (AV) conduction in mammalian hearts. Thus we studied the dromotropic effects of CNP-22 injected into the AV node artery in autonomically decentralized hearts in open-chest, anesthetized dogs. CNP decreased AV interval (AV conduction time) in a dose-dependent manner with increase in coronary artery blood flow rate in six anesthetized dogs. Isosorbide dinitrate did not affect AV interval, but it increased coronary artery blood flow rate. A guanylyl cyclase-linked natriuretic peptide receptor antagonist, HS-142-1, inhibited the decreases in AV interval and the increases in coronary blood flow rate in response to CNP, whereas propranolol did not affect the positive dromotropic response to CNP. These results demonstrate that CNP decreases AV interval and increases coronary artery blood flow rate mediated by a guanylyl cyclase-linked natriuretic peptide receptor, but not β-adrenoceptor, in the dog heart.

The influence of spontaneous termination of atrial fibrillation on P wave-triggered signal-averaged electrocardiogram.

BACKGROUND Prolongation of total filtered P wave duration (Ad) and low root mean square voltages for the last 20 ms of the P wave (LP20) on a P wave-triggered signal-averaged electrocardiogram (PSAECG) are typically observed in paroxysmal atrial fibrillation (PAF) patients. A shortening of atrial refractoriness and intra-atrial conduction delay (atrial remodeling) have been shown to occur in response to PAF. We, therefore, investigated the effects of spontaneous termination of PAF on the parameters of PSAECG. METHODS We measured the Ad, LP20 and left atrial (LA) diameter by ultrasonic echocardiography before, within 1 h after, and 3 and 12 months after PAF termination in patients with no structural heart disease (n=11). RESULTS The PAF duration was 16+/-5 h. The Ads before, within 1 h after, and 3 and 12 months after PAF were 137+/-4, 148+/-4, 137+/-6, and 135+/-7 ms, respectively. The Ad within 1 h after PAF was significantly (P<0.01) longer than at the other three acquisition points. Although the LP20 within 1 h after PAF termination was not significantly different from the other three points, the change in LP20 (within 1 h after PAF-before PAF, -1.1+/-0.4 microV) in the long PAF duration group was significantly (P<0.05) greater than that of the short PAF duration group. LA diameter was unchanged at all points. CONCLUSION These data suggest that PAF results in prolongation of Ad after termination of PAF.

Intravascular Ultrasound‐Guided Percutaneous Balloon Angioplasty for Membranous Obstruction of the Inferior Vena Cava

A 50-year-old Japanese woman who had been suffering from leg edema and pigmentation for 3 years was admitted to our hospital and received a diagnosis of Budd-Chiari syndrome. Esophageal varices that had been deFigure 1. Inferior vena cavogram shows a membranous obstruction (white arrow) of the inferior vena cava (IVC) near its entry into the right atrium (RA) A. Intravascular ultrasound of the IVC reveals a rounded membrane (white arrowheads), decreasing in size from bottom to top and spontaneous echo contrast within the membrane B.