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Biomedical subjects

T Akiba

Publications and source records attributed to T Akiba.

At least 109 records · Page 6Linked to original sources
PubMed1994

Balloon pulmonary valvuloplasty for double outlet right ventricle with valvular pulmonary stenosis.

A male neonate presented with cyanosis. Echocardiograms showed a double outlet right ventricle, an absent outlet septum, a subaortic ventricular septal defect and valvular pulmonary stenosis. Balloon pulmonary valvuloplasty was performed at 19 days of age, resulting in an immediate increase of the systemic arterial oxygen saturation from 67 to 87%. As far as could be found, this is the first report of a patient with a double outlet right ventricle without the outlet septum who was clinically observed and underwent balloon pulmonary valvuloplasty.

Catheterization↗
PubMed1994

Histopathologic findings of lung vessels in five children with primary pulmonary hypertension.

A histopathologic study was carried out on pulmonary vessels of lung tissues from 5 children with primary pulmonary hypertension (PPH), in whom diagnosis was made on the basis of cardiac catheterization. Histological sections of lung were obtained in 4 patients by open lung biopsy and in one patient by closed needle necropsy soon after death. In all cases the vascular diseases were classified as grade 6 of the Heath-Edwards. Morphologic studies of small pulmonary arteries revealed medial hypertrophy (41.0%), intimal cellular proliferation (2.5%), intimal fibroelastic proliferation (36.9%) and medial destructive changes (19.6%) such as dilatation lesions, plexiform lesions, arteritis, or fibrinoid necrosis. Index of pulmonary vascular disease (IPVD) was 1.6 to 3.4 (mean 2.5). The advancement of these pulmonary changes sufficiently explains the extremely poor prognosis of children with PPH.

Adolescent↗
PubMed1994

Changes in molecular pattern of atrial natriuretic peptide in hemodialysis patients.

An attempt was made to clarify whether the molecular forms of atrial natriuretic peptide (ANP) in the plasma of stable hemodialysis patients differ from those of healthy volunteers, and whether the ANP molecular forms in plasma might change during hemodialysis treatment. Ten stable hemodialysis patients with no clinical signs of cardiac disease were treated for 4 hours by a hollow fiber-type dialyzer. Plasma ANP concentrations before dialysis were 210 +/- 101.6 pg/ml (mean +/- SD), which were significantly higher than that of volunteers (59.2 +/- 37.2 pg/ml, n = 25). They were significantly decreased to 71.6 +/- 60.1 pg/ml after dialysis. Molecular patterns of ANP were measured by gel permeation chromatography and reverse-phase high performance liquid chromatography. Immunoreactive alpha-ANP peaks of GPC, which co-migrated with authentic alpha-, beta-, and gamma-ANP, were supposed to be alpha-, beta-, and gamma-ANP. The plasma of four patients contained a beta-ANP peak before dialysis, and three of the four still contained a beta-ANP peak after dialysis. These results showed that the middle-molecular-weight ANP, which co-migrated with authentic beta-ANP and is supposed to be beta-ANP, may particularly be secreted in clinically stable hemodialysis patients.

Adult↗
PubMed1994

[Tetralogy of Fallot with absent pulmonary valve: a successful case by total corrective surgery in 25 days old infant].

A 25 days old neonate of tetralogy of Fallot with absent pulmonary valve underwent total corrective surgery which consisted of VSD patch closure, resection of anterior wall of both pulmonary arteries and right ventricular outflow tract reconstruction using a monocuspid equine pericardial patch. Postoperatively, the right pulmonary artery diameter decreased from 17.8 mm (307%N) to 7.5 mm (129%N) and the left pulmonary artery diameter from 16.9 mm (338%N) to 8.3 mm (166%N). The patient was weaned from the ventilator 2 days after operation, whose post-operative course was uneventful. Total corrective surgery may provide a great success to symptomatic patients during the neonatal period.

Cardiac Surgical Procedures↗
PubMed1994

Electrophoretic free mobility and viability of microbial cells: a preliminary study in preparation for space experiments.

Electrophoretic free mobilities (EFM) of four fungal spores and five bacterial cells were determined in 7 mM triethanolamine/acetate (TEA) buffer by means of microscopic electrophoresis (ME) and free flow electrophoresis (FFE). Spores of Aspergillus terreus, Penicillium citrinum, Gliocladium virens, and Rhizopus oryzae had similar EFM from 2.2 to 3.1 microns sec-1/V cm-1. The resolution of the spore mixture by FFE was therefore determined to be poor. Bacterial cells of Salmonella typhimurium LT2 mutants showed a distinctive EFM from 0 to 4.2 microns sec-1/V cm-1, which is a large enough difference to produce a clear separation of each mutant type from the mixture in FFE. The differences in the EFM of bacteria result from defective structures in the lipopolysaccharide of their outer membranes. The viability of bacteria in TEA buffer at 4 degrees C was investigated, and it was found to be stable for 14 days. This period is long enough to allow the performance of space experiments.

Aspergillus↗
PubMed1994

Disease of the left ventricle in pulmonary atresia with intact ventricular septum. The limiting factor for long-lasting successful surgical intervention?

Eight hearts with pulmonary atresia with intact ventricular septum were studied grossly and microscopically. The right ventricle was composed of inlet, infundibular, and trabecular portions in two hearts, without trabecular portions in three hearts, and consisted of an inlet part only in another three hearts. Pulmonary atresia was classified as membranous in two hearts; the other six hearts had muscular atresia. The left ventricle showed a range of abnormalities, albeit mostly discrete. A mitral valve with short tendinous chords was present in four hearts; one of these had a cleft mitral valve. All hearts (except the heart of a 1-day-old neonate) had a prominent subaortic septal bulge. All hearts had left ventricular hypertrophy, which exceeded twice the standard deviation of normal in two patients. None of the hearts had histologic features of hypertrophic cardiomyopathy. The density of intramyocardial coronary arteries was normal in each patient, but medial thickening (20 to 100 microns diameter arteries) had occurred in four patients. Signs of acute myocardial ischemia (hydropic cell swelling) were present in all; one heart (the oldest case of 6 months) contained areas of replacement fibrosis and calcifications indicative of previous infarction. Quantification of the volume density of endomysial (interfiber) collagen (Picrosirius red microspectrophotometry) showed high levels in all, within the range of normal in five patients, but exceeding twice the standard deviation of normal in three patients. In all cases the values obtained in the subendocardial layers were higher than those obtained subepicardially. The observations show that the left ventricle in hearts with pulmonary atresia with intact ventricular septum contains abnormalities that may render the left ventricle less capable to cope with a volume load. The high values of endomysial (interfiber) collagen suggest chronic ischemia in relation to left ventricular hypertrophy as the main mechanism involved. Therefore, as a late consequence, the left ventricle could be the limiting factor for long-lasting successful surgical intervention.

Coronary Vessels↗
PubMed1993

Expression of bone morphogenic protein 7 mRNA in MDCK cells.

Recently, a family of proteins, bone morphogenic proteins (BMPs), have been identified, which promote osteoblast differentiation and bone mineralization. One of them, BMP7, has been shown to be expressed at high levels in the kidney. We detected the message in a kidney tubular cell line, Madin-Darby canine kidney (MDCK) cells. After serum starved for 48h, 8-bromo-cAMP enhanced BMP7 mRNA at 3h and forskolin enhanced it at 6h to 24h in MDCK cells. PMA increased BMP7 mRNA at 6h but down-regulated it at 12h and 20h. The result suggests that BMP7 gene expression may be regulated in MDCK cells by PKA and PKC. MDCK cells can be used in further studies of BMP7 regulation.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1993

Valve morphology in complete atrioventricular septal defect: variability relevant to operation.

The remodeling of the atrioventricular valves in patients with complete atrioventricular septal defects is the crucial part of surgical repair. Variability in valve morphology is an important factor. This study evaluates the variability in morphology of the anterior and posterior leaflets in 30 heart specimens. All hearts had an anterior bridging leaflet: Rastelli type A in 12, type B in 2, and type C in 16. The posterior leaflet revealed four morphologic patterns: a right- and left-sided posterior leaflet, both inserting directly onto the crest of the ventricular septum (5 hearts); a common posterior leaflet attached to the septal crest by a membrane (2 hearts); a common posterior leaflet attached to the septal crest by multiple chordae (13 hearts); and a virtually free-floating posterior leaflet (11 hearts). The categorization is surgically relevant in making a distinction between hearts with and without an interventricular communication underneath the posterior leaflet. Surgically relevant variations occurred also in arrangement and positioning of chordae originating from the right septal side. There was no relationship between the Rastelli classification of the anterior leaflet and that of the posterior leaflet. The variability in morphology of the posterior leaflet and its attachments to the ventricular septum appear equally crucial for successful repair as that of the anterior leaflet.

Chordae Tendineae↗
PubMed1993

Decreased lithium clearance in patients with hyperthyroidism.

Lithium clearance was studied to investigate proximal tubular function in patients with hyperthyroidism (n = 10) and control subjects (n = 7). Patients with hyperthyroidism showed significantly reduced fractional excretion of lithium (FELi) compared with control subjects (15.0 +/- 1.5%, n = 10, vs. 23.7 +/- 0.6%, n = 7, means +/- SE, p < 0.001). The reduced FELi of the hyperthyroid state was reversed toward control values with treatment by antithyroid drugs (12.6 +/- 2.6 toward 26.8 +/- 2.5% for 5 patients, means +/- SE). Tubular reabsorption of phosphate (TRP) was significantly increased in hyperthyroid patients compared with control subjects (96.1 +/- 0.7 vs. 87.5 +/- 0.7%, p < 0.001), and it returned to control values after the treatment. Our data demonstrate that lithium clearance is decreased and TRP is increased in patients with hyperthyroidism, which suggests that proximal tubular reabsorption of sodium and TRP is increased in hyperthyroidism.

Adult↗
PubMed1993

[Study on the glomerular foam cells in stroke-prone SHR].

Recent evidence suggests focal glomerulosclerosis may be analogous to atherosclerosis. To investigate the role of hypertension and hypercholesterolemia in the appearance of glomerular foam cells, 2, 6 or 9-month-old stroke-prone SHR (SHRSP) were fed the high fat cholesterol diet (2% cholesterol, 0.5% cholic acid, 7% lard, 0.2% methylthiouracil; HFC) for 4 weeks. Serum total cholesterol was significantly elevated in HFC. Form cells were observed in glomeruli of 6- and 9-month-old, but not 2-month-old SHRSP with dietary-induced hypercholesterolemia. The glomerular foam cells varied in quantity almost in parallel with the duration of severe hypertension. Glomeruli with foam cells prominently situated in juxtamedullary region. Foam cells were frequently seen in glomerular sclerotic area. These results suggest that hypertension rather than hyperlipidemia may be more important for glomerular deposition of lipid, especially in early lesions, and hyperlipidemia may play a role in the foam cells accumulation.

Animals↗
PubMed1993

Dilazep prevents glomerulosclerosis in accelerated Masugi nephritis in the rat.

The effects of Dilazep on immunologically induced glomerular injuries were examined. Accelerated Masugi nephritis in rats produced glomerulosclerosis with proteinuria following administration of a single dose of nephrotoxic serum (NTS). When 5 mg/kg/day of Dilazep had been administered prior to the NTS injection, the proteinuria was resolved rapidly after reaching a maximum level. The glomeruli 3 months later showed significant suppression of glomerulosclerosis and lesser adhesive lesions as compared to those in control rats with Masugi nephritis. On the other hand, when Dilazep was administered from 2 weeks after the injection of NTS, the rats displayed persistent proteinuria and glomerulosclerosis at similar levels to those in the Masugi group. Dilazep appears to exert some protective effects in the early stages of glomerular injuries induced by immunological mechanisms.

Animals↗
PubMed1993

Is there an anatomic basis for subvalvular right ventricular outflow tract obstruction after an arterial switch repair for complete transposition? A morphometric study and review.

The study was initiated by reports on right ventricular outflow tract obstruction in complete transposition of the great arteries after an arterial switch repair. We investigated 39 heart specimens with native, unoperated transposition of the great arteries. Of these, 14 hearts had a ventricular septal defect; 25 had an intact ventricular septum. In each heart specimen the narrowest site of the subaortic outflow tract was measured and compared with the circumference of the aortic orifice. Obstruction was considered to be present if the outflow tract circumference was less than that of the aortic orifice. In addition, the diameter of the ascending aorta immediately above the level of the valve orifices was measured and compared with that of the pulmonary trunk. An obstruction was present in the subaortic right ventricular outflow tract of two hearts (5.1%): one of the obstructions, in a neonatal heart with intact ventricular septum, was caused by a prominent supraventricular crest and anterior trabeculations; the other obstruction was an additional extensive muscular hypertrophy, in the heart of a 13-year-old patient with a similar anatomy, and a septal defect. A mismatch between the diameters of the ascending aorta and the pulmonary trunk was present in 15 of 32 hearts measured. Our observations and a review of the literature confirm that subvalvular right ventricular outflow tract obstruction in hearts with native transposition of the great arteries is infrequent. Nevertheless, the anatomic characteristics of the right ventricular outflow tract are such that the tract is intrinsically narrow and muscular hypertrophy may easily lead to obstruction. After an arterial switch operation, subvalvular obstruction could be caused by dynamic processes analogous to those observed after relief of isolated pulmonary valve stenosis. Anatomic subvalvular obstruction could be due to either an obstruction that was not identified before operation or (a purely speculative hypothesis) subtle degrees of mismatch in size between the proximal aorta and the pulmonary trunk, which may be considered irrelevant at time of operation but may also set into pace a process of ongoing adaptive infundibular hypertrophy.

Academic Medical Centers↗
PubMed1993

[Case report of metastatic cutaneous angiosarcoma causing bilateral pneumothorax].

The patient was a 72-year-old man who underwent operation for bilateral pneumothorax due to rupture of cystic lung lesions. Two months after the operation, intrathoracic bleeding redeveloped. The patient developed a tumor on his head. Pathological examination of the scalp lesion revealed cutaneous angiosarcoma. A biopsy of thickened pleura showed that the bleeding was due to pleural metastatic angiosarcoma of the skin. The multiple cystic lesions were considered to be metastases of angiosarcoma. We conclude that pneumothorax or hemothorax in the elderly should be differentiated from malignant metastatic lung tumor. Cystic lung lesions should be considered as possible metastatic angiosarcoma from the skin.

Aged↗
PubMed1992

Central alpha-adrenoceptor subtypes involved in the emetic pathway in cats.

The intracerebroventricular (i.c.v.) injection of clonidine, xylazine, adrenaline and methoxamine elicited dose-dependent vomiting in cats in that order of potency. The vomiting induced by clonidine, xylazine and adrenaline was antagonized by i.c.v. yohimbine and phentolamine possessing alpha 2-adrenoceptor-blocking activity, but not by prazosin showing alpha 1-adrenoceptor-blocking activity. In contrast, methoxamine-induced vomiting was antagonized by prazosin, but not by yohimbine. The vomiting induced by xylazine and adrenaline was not prevented by i.c.v. 6-hydroxydopamine treatment, but was prevented by i.c.v. reserpine treatment. Ablation of the area postrema with some damage to extremely adjacent areas abolished the vomiting induced by each alpha-adrenoceptor agonist. These results indicate that both central alpha 1- and alpha 2-adrenoceptors are involved in the emetic pathway in cats, although alpha 2-adrenoceptors seem to have the main role. It is also suggested that monoamines, and in particular 5-hydroxytryptamine in the brain, are involved in the regulation of alpha-adrenoceptor-mediated vomiting.

Adrenergic alpha-Agonists↗
PubMed1992

Endothelin receptors in human parathyroid gland.

We studied whether specific receptors for endothelins (ETs) exist in human parathyroid tissues and whether ETs may have any effect on secretion of PTH from parathyroid cells. Binding studies using [125I]ET-1 to the parathyroid membranes obtained from patients with hyperparathyroidism (2 adenomas, 2 hyperplasias) revealed that ET-1 competitively inhibited the binding of [125I]ET-1 to the membranes (the apparent Kd: 62 +/- 18 pM), whereas ET-3 showed biphasic and less steep inhibition curve than ET-1 in all tissue membranes examined. Northern blot analysis of poly(A)+ RNA from the parathyroid adenoma clearly demonstrated gene expression of both ETA and ETB receptors as well as preproET-1. ET-1 inhibited basal PTH secretion from dispersed adenoma cells more potently than ET-3. The present study clearly demonstrates the presence of both ETA and ETB receptor subtypes in human parathyroid tissues through which ETs may modulate PTH secretion in an autocrine and/or paracrine manner.

Adenoma↗
PubMed1992

Estimation of right ventricular pressure in children by thallium-201 myocardial imaging using single-photon emission computed tomography.

Thallium-201 myocardial imaging using single-photon emission computed tomography was performed to estimate right ventricular (RV) systolic pressure in 34 children (aged 4.1 to 16.1 years, mean 7.9 +/- 2.9). Acquisition of the images was performed using a semicircular arc of 180 degrees. On a short-axis slice, a line drawn perpendicular to the ventricular septum so as to cross the RV free wall showing maximum uptake was defined as the region of interest. Thallium-201 counts in regions of interest over both RV and left ventricular (LV) free walls were measured. The ratio of RV-to-LV peak thallium-201 counts was compared with RV peak systolic pressure and the ratio of RV-to-LV peak systolic pressure measured at cardiac catheterization. Both RV peak systolic pressure and the ratio of RV-to-LV peak systolic pressure correlated well with the ratio of RV-to-LV peak thallium-201 counts (r = 0.95 and 0.96, respectively). The ratio of RV-to-LV peak thallium-201 counts greater than or equal to 0.45 could predict RV pressure overloading with a sensitivity of 92%, and a specificity of 88%. Thus, the quantitative analysis of thallium-201 myocardial imaging using single-photon emission computed tomography permits the noninvasive and accurate estimation of RV systolic pressure in children.

Adolescent↗
PubMed1992

Haloalkaliphilic maltotriose-forming alpha-amylase from the archaebacterium Natronococcus sp. strain Ah-36.

A haloalkaliphilic archaebacterium, Natronococcus sp. strain Ah-36, produced extracellularly a maltotriose-forming amylase. The amylase was purified to homogeneity by ethanol precipitation, hydroxylapatite chromatography, hydrophobic chromatography, and gel filtration. The molecular weight of the enzyme was estimated to be 74,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amylase exhibited maximal activity at pH 8.7 and 55 degrees C in the presence of 2.5 M NaCl. The activity was irreversibly lost at low ionic strength. KCl, RbCl, and CsCl could partially substitute for NaCl at higher concentrations. The amylase was stable in the range of pH 6.0 to 8.6 and up to 50 degrees C in the presence of 2.5 M NaCl. Stabilization of the enzyme by soluble starch was observed in all cases. The enzyme activity was inhibited by the addition of 1 mM ZnCl2 or 1 mM N-bromosuccinimide. The amylase hydrolyzed soluble starch, amylose, amylopectin, and, more slowly, glycogen to produce maltotriose with small amounts of maltose and glucose of an alpha-configuration. Malto-oligosaccharides ranging from maltotetraose to maltoheptaose were also hydrolyzed; however, maltotriose and maltose were not hydrolyzed even with a prolonged reaction time. Transferase activity was detected by using maltotetraose or maltopentaose as a substrate. The amylase hydrolyzed gamma-cyclodextrin. alpha-Cyclodextrin and beta-cyclodextrin, however, were not hydrolyzed, although these compounds acted as competitive inhibitors to the amylase activity. Amino acid analysis showed that the amylase was characteristically enriched in glutamic acid or glutamine and in glycine.

Amino Acids↗