Biomedical subjects
Publications and source records attributed to K Momma.
In infants with a large ventricular septal defect, the acute hemodynamic effect of intravenous digitalis varies depending on baseline systemic and pulmonary resistance. Digitalis may act adversely by increasing pulmonary blood flow with an elevation in left atrial pressure in severely congested infants with ventricular septal defects.
In a family with long QT syndrome (LQT2), some individuals who did not harbor the HERG mutation had a prolonged QTU interval on electrocardiograms after exercise. It may be determined or modified by other gene(s) or factor(s). The sequence analysis of mtDNA in these individuals of this family showed a candidate pathogenic mutation at 3394 in the ND1 gene. The cybrids (mutation at 3394) showed significantly reduced NADH-CoQ reductase (complex I) activity and O2 consumption to normal levels. These inhibitory effects on respiratory function may result in the depletion of ATP and could possibly produce an increase in Ca2+ concentration in cytosol, and it may lead to the prolongation of the QTU intervals on electrocardiograms. Therefore, we stated that the 3394 mutation in the ND1 gene is pathogenic and could be the cause of prolongation of the QTU intervals or modification of the phenotypes of not only congenital but also so-called "acquired drug-induced long QT syndrome."
Previous reports regarding intravascular ultrasound (IVUS) imaging of the pulmonary arteries in children and its application to balloon pulmonary angioplasty are limited. This study was designed to compare findings of IVUS imaging and those of angiography of the pulmonary artery before and after the balloon angioplasty procedure. Thirty patients had significant pulmonary artery stenosis and underwent balloon angioplasty. In all, of 34 branch pulmonary arteries were dilated. All patients underwent both angiography and IVUS imaging at the time of balloon angioplasty. The mean age at balloon angioplasty was 5.7 +/- 4.0 yr. One echo-dense layer on IVUS was detected in 9% of the 34 stenotic vessels, and a two- or three-layered vascular wall pattern in 91%. The thickness of intima-medial layer (inner and middle layers) was greater than normal in 91% of stenotic vessels. After balloon angioplasty, intimal flaps and aneurysm were observed at 29 and 28 locations, respectively. Of these locations, the intimal flaps were detected by angiography in 44% and by IVUS in 100%; the aneurysm was detected by angiography in 61% and by IVUS in 93%. Media rupture was observed at 26 locations, and the change was detected only by IVUS. The present study suggests that intimal and medial changes in the pulmonary artery can be detected more precisely by IVUS than by angiography.
We analyzed the electron-microscopic features of endomyocardial biopsy from pediatric patients with dilated cardiomyopathy (DCM). The specimens examined were taken from the right ventricle of ten patients aged from 2 to 15 years (mean 9.7 years). Biopsy specimens from eight patients with congenital heart disease (tetralogy of Fallot), aged from 3 to 12 (mean 7.3 years), and ten adult patients with DCM, aged from 32 to 60 (mean 45 years), were also examined. Patients considered to have endocardial fibroelastosis, arrhythmogenic right ventricular cardiomyopathy, specific cardiomyopathy, or coronary heart disease were excluded from this study. Specimens from pediatric patients with DCM showed various degrees of ultrastructural abnormalities of myocytes, including myofibrillar fragmentation, mitochondrial abnormalities, and intracellular edema. The ultrastructurally determined contractility failure index based on the severity of myocardial degeneration at the electronmicroscopic level was 4.9 +/- 1.1. This value was significantly higher than that in patients with tetralogy of Fallot (0.9 +/- 0.6, P < 0.001) but was not significantly different from that in adult patients with DCM (6.1 +/- 2.6). The index of pediatric patients with DCM who died within 3 years was high (6.0 +/- 0.8). Basal lamina layering of a capillary (BLL) in the myocardium was revealed in 1 of the 10 (10%) pediatric patients with DCM and in 6 of the 10 (60%) adult patients with DCM (P < 0.05). No BLL was noted in the patients with tetralogy of Fallot. These findings may be related to the pathogenesis of DCM in children and adults.
When microorganisms utilize macromolecules for their growth, they commonly produce extracellular depolymerization enzymes and then incorporate the depolymerized low-molecular-weight products. Assimilation of heteropolysaccharides (gellan and xanthan) by Bacillus sp. GL1 depends on this generally accepted mechanism. On the other hand, Sphingomonas sp. A1 represents an unexplored specific and interesting system for macromolecule assimilation. In the presence of heteropolysaccharide (alginate), the bacterium forms a mouthlike pit on its cell surface and directly incorporates the macromolecule using a novel ATP-binding cassette transporter (ABC transporter). In this review, we discuss enzymatic and genetic bases on the depolymerization and assimilation routes of heteropolysaccharides in bacteria, with particular emphasis on the novel incorporation system for macromolecules, characteristic post-translational modification processes of polysaccharide lyases and on the mouthlike pit structure on the bacterial cell surface.
OBJECTIVES: The purpose of this study was to clarify the clinical characteristics of interruption of the aortic arch associated with chromosome 22q11deletion. BACKGROUND: About half of patients with interruption of the aortic arch between the left common carotid and the left subclavian artery have deletion of chromosome 22q11. METHODS: In total, 20 patients with interruption of the aortic arch were studied with fluorescence in situ hybridization using peripheral lymphocytes and a DiGeorge syndrome chromosomal probe (Oncor N25). Cardiovascular anomalies in these patients were diagnosed by cross-sectional echocardiography and angiocardiography, and were confirmed at intracardiac repair. RESULTS: Of 13 patients with interruption between the left common carotid artery and the left subclavian artery, seven had the deletion. All 7 also showed thymic hypoplasia and hypocalcemia, together with a nasal voice and peculiar facies. Six of the seven patients had complete deficiency of the muscular outlet septum, with the defect extending to the perimembranous area. Such complete absence of the muscular outlet septum was not present in any of the patients without the deletion. CONCLUSIONS: Interruption of the aortic arch between the left common carotid and the left subclavian artery, absence of the thymus, and complete absence of the muscular outlet septum, were characteristic in Japanese patients with interruption of the aortic arch associated with deletion of chromosome 22q11.
We report two autopsy proven cases of unguarded mitral orifice associated with mirror-imaged atrial arrangement, discordant atrioventricular connections, double outlet right ventricle, pulmonary valvar stenosis or atresia, and atrialisation of the morphologically left ventricle. The morphologically left atrioventricular junction was devoid of valvar leaflets, and there was no tension apparatus within the ventricle. To the best of our knowledge, this is the first description of this rare cardiac malformation.
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A bacterium isolated from soil as an alginate lyase producer shows characteristic morphological and taxonomical properties consistent with being classified in the genus Sphingomonas. The bacterium utilizes high molecular weight (HMW)-alginate for growth by depolymerization of the polymer with intracellular alginate lyases, which are generated from a common precursor protein through autoregulated post-translational modifications. Electron microscopic observations of the cell surface and of thin sections of cells grown on HMW-alginate revealed dynamic changes in both cell surface and membrane structures. The most remarkable change is recognized in the formation of mouth-like pits which open and close depending on the presence or absence of HMW-alginate. Enzymatic and genetic analyses of HMW-alginate incorporation processes confirmed the presence of a pit-dependent and macromolecule-specific ABC transporter system in cells of Sphingomonas species A1. This is the first description of a bacterium with a pit on the cell surface and a pit-dependent endocytosic uptake system for macromolecules.
PURPOSE: The present study aimed to investigate the clinicopathologic findings and histopathologic characteristics of endomyocardial biopsy in pediatric patients with idiopathic ventricular tachycardia. METHODS: Histopathological findings of endomyocardial biopsy from 17 patients aged 7-15 years with idiopathic ventricular tachycardia (VT) but no organic heart disease were examined. Patients considered to have cardiomyopathy of the dilated, hypertrophic or specific form or arrhythmogenic right ventricular cardiomyopathy were excluded from this study. RESULTS: Advanced histopathologic findings, including myocyte hypertrophy, degeneration, interstitial fibrosis and disarrangement of muscle bundles, were disclosed in three cases (17.6%). One of these cases exhibited sustained VT with left bundle branch block configuration and showed increased frequency of VT during exercise testing. The remaining two cases had non-sustained VT with multifocal origin and had syncope episodes. Another 14 cases showed mild or no significant findings in the biopsy. CONCLUSIONS: These results indicate that advanced histopathology in endomyocardial biopsy is occasionally disclosed in cases of idiopathic VT, especially those of exercise-related VT or multifocal VT, and that these patients may be considered as having heart muscle disease.
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Prostaglandin E is a major dilator of the fetal ductus arteriosus (DA), but the role of nitric oxide in fetal ductal dilation has not been established. We studied the effects of a potent nitric oxide synthase inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME), on the fetal DA in rats. L-NAME was injected into the dorsum of pregnant rats, and fetal DA was studied 4 h later with a rapid whole body freezing method. The inner diameters of the DA and the main pulmonary artery were measured on a freezing microtome. The inner diameter ratio of DA to main pulmonary artery (DA/PA) was 1.02+/-0.03 (mean +/- SEM; number of fetuses [n], 21) in normal near-term fetuses. The effect of prostaglandin synthesis inhibition was studied after orogastric administration of indomethacin to pregnant rats. In near-term rats on the 21st day of gestation (term, 21.5 d), a large dose of L-NAME (100 mg/kg) caused only mild ductal constriction, with DA/PA reduced to 0.83+/-0.05 (n = 20). Indomethacin (1 mg/kg) caused moderate ductal constriction, and DA/PA was decreased to 0.65+/-0.05 (n = 21). Combined administration of L-NAME (10 mg/kg) and indomethacin (1 mg/kg) caused severe ductal constriction, with DA/PA of 0.26+/-0.03 (n = 16). In preterm rats on the 19th day of gestation, a moderate dose of L-NAME (10 mg/kg) caused severe ductal constriction, with a DA/PA of 0.32+/-0.05 (n = 24). Indomethacin (1 mg/kg) alone caused only mild ductal constriction, with DA/PA 0.86+/-0.02 (n = 16). In conclusion, prostaglandin has a major role and nitric oxide has a minor role in dilating the DA in the near-term fetal rat. In contrast, nitric oxide has a major role and prostaglandin has a minor role in dilating the DA in preterm fetal rats.
Prostaglandin E1 incorporated in lipid microspheres (lipo PGE1) was administered to the umbilical vein of neonatal rats. Morphological measurement and quantitative autoradioluminography assessed the relationship between the vasodilating effect and tissue accumulation of lipo PGE1 in the ductus arteriosus. In the morphological measurement under microscopy, the inner diameter ratio of the ductus arteriosus to the main pulmonary artery after infusion of 3H-labeled lipo PGE1 (3H-lipo PGE1) continued to remain significantly higher than that of free 3H-PGE1. Autoradioluminography of the frozen frontal section of neonates after intravenous infusion of 3H-lipo PGE1 for 2 h revealed that the ductus levels of radioactivity were higher than those of free 3H-PGE1 in saline solution, although the blood levels were almost equal. Localization of lipo PGE1 labeled with a lipophilic fluorescent probe, 1,1'-dioctadecyl-3,3,3',3-tetramethyl-indocarbocyanine perchlorate (diI), in the endothelial cells of the ductus arteriosus was confirmed by confocal laser scanning microscopy. These findings suggest that the incorporation of lipid microspheres by the endothelial cells is one of the mechanisms that enables lipo PGE1 to accumulate to higher levels in the ductus tissue and to act more efficiently than free PGE1 in neonatal rats.
Feeding studies of transgenic potatoes with native and designed soybean glycinins in rats were done for four weeks. The designed glycinin has four additional methioninyl residues in the middle of the glycinin molecule. Rats were divided into four groups fed (I) only a commercial diet, (II) the diet plus non-transgenic potatoes, (III) the diet plus transgenic potatoes with native glycinin, and (IV) the diet plus transgenic potatoes with designed glycinin. Rats were fed 2,000 mg/kg-weight potatoes every day by oral administration. During the period tested, rats in each group (groups II, III, and IV) grew well without marked differences in appearance, food intake, body weight, or in cumulative body weight gain. No significant differences were also found in blood count, blood composition, and in internal organ weights among the rats after feeding potatoes (groups II, III, and IV) for four weeks. Necropsy at the end of experiment indicated neither pathologic symptoms in all rats tested nor histopathological abnormalities in liver and kidney. Judging from these results, the transgenic potatoes with glycinins are confirmed to have nearly the same nutritional and biochemical characteristics as non-transgenic one.
The composition of nutritionally and physiologically important molecules in transgenic rice with the soybean glycinin gene was determined and compared with that of a non-transgenic control. Except for the levels of protein, amino acids and moisture, no marked differences were found between the two kinds of rice. The protein content of the transgenic rice was about 20% higher than the control (control, 6.5 g/100 g; transgenic, 8.0 g/100 g) with a concomitantly lower moisture content. This increased protein content mainly resulted from the increased glycinin expressed in the transgenic rice, and the protein was susceptible to gastric and intestinal digestion juices. In parallel with the increased protein content, some important amino acids lacking in quantity in normal rice were replenished.
In smooth muscle tissue, two smooth muscle myosin heavy chain (MHC) isoforms (SM1, SM2) and two non-muscle MHC isoforms (NMA, NMB) have been identified. The purpose of our study was to clarify whether smooth muscle MHC mRNA expression reflects the physiological and functional state of the muscle. We studied the expression pattern of MHC mRNAs, using the S1-nuclease mapping procedure, in functionally and morphologically changeable organs; the ductus arteriosus (DA) during development (25 and 29 days of gestation, and from 3-day-old neonates) and uteri from virgin, day-10 pregnant (P10) and day-29 pregnant (P29) rabbits. The results demonstrated that SM2 expression was greater in the fetal DA than in the fetal aortic and pulmonary arteries, but that it decreased significantly following closure of DA. In the gravid uterus, SM1 expression was significantly (P<0.05) strong compared to other MHC mRNAs from virgin to P10 rabbits. During pregnancy, NMB expression showed a tendency to increase until P10, and after P10, SM2 expression increased dramatically and NMB expression decreased to give almost a mirror image of the SM2 expression. Smooth muscle type (SM1, SM2) was significantly (P<0.05) strong compared to non-muscle type expression (NMA, NMB) at P29. These data suggest that smooth muscle MHC mRNA, especially SM2 expression reflects the physiological and functional state of the smooth muscle.
We report on male monozygotic twins with 22q11.2 deletion and discordant phenotypes. The twins had twin-to-twin transfusion syndrome. Twin 1, the smaller of the pair, had Tetralogy of Fallot, a characteristic facial appearance, swallowing dysfunction, anal atresia, short stature, and mental retardation, whereas twin 2 had a characteristic facial appearance but no other signs of the 22q11 deletion syndrome. Fluorescence in situ hybridization analysis showed a microdeletion on chromosome 22q11.2 in both twins. Zygosity analysis gave a probability of monozygosity greater than 99.999%. These observations indicate that environmental factors or postzygotic events play a role in the phenotypic variability in the twins.
BACKGROUND: Sympathetic cardiopulmonary nerves arise from the cervical sympathetic trunks and the stellate ganglia and subsequently course along the origin of the great arteries and the coronary arteries to innervate the ventricles. Therefore, the sympathetic nerves may be obligatorily interrupted by the arterial switch operation (ASO) for complete transposition of the great arteries. METHODS AND RESULTS: To demonstrate and characterize the possible sympathetic denervation, 51 patients after ASO, 4.8 years old (range, 1 month to 10.1 years), underwent [123I]metaiodobenzylguanidine (MIBG) imaging of the sympathetic nerve terminal. MIBG uptake to the heart was graded by quantitative analysis using the heart-to-mediastinum (H/M) ratio of MIBG uptake. A quantitative criterion for absent uptake of MIBG was set to 1.48 in the H/M ratio. Four patients < 1 month after ASO showed complete absence of MIBG uptake, which had been observed preoperatively. In contrast, 47 patients late after ASO (range, 15 months to 10.1 years) showed various degrees of uptake of MIBG. Patients operated on at < or =55 days of age showed positive MIBG uptake much more frequently than those operated on at later ages. Heart rate and rate-pressure product at peak exercise on a treadmill exercise test were significantly greater in patients with positive uptake than in those with absent uptake of MIBG. CONCLUSIONS: Cardiac sympathetic nerves were denervated early after and reinnervated late after ASO. Neonatal ASO may be favorable to facilitate sympathetic reinnervation, which may affect exercise tolerance late after surgery.