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Biomedical subjects

H Imai

Publications and source records attributed to H Imai.

At least 505 records · Page 28Linked to original sources
PubMed1986

Cardiotonic and coronary vasodilatatory effects of amrinone in the canine heart-lung preparation with a support dog as compared with those of dobutamine.

Analysis of the relative magnitude of the positive inotropic and chronotropic effects and the coronary vasodilating effects of amrinone conducted in the canine heart-lung preparation with a support dog in comparison with those of dobutamine demonstrated that amrinone was a preferential coronary vasodilator rather than a selective positive inotropic agent. An in vitro experiment in the canine papillary muscle suggested the initiation of the slow response action potential as a mechanism of the positive inotropic effect of amrinone.

Aminopyridines↗
PubMed1986

Postoperative left ventricular function in patients with mitral stenosis. The effect of commissurotomy and valve replacement on left ventricular systolic function.

Preoperative and postoperative left ventricular cineangiograms of 26 patients with mitral stenosis (MS) were analyzed to calculate left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and systolic regional wall motion. Nine patients underwent commissurotomy (OMC group) and 17 patients underwent mitral valve replacement (MVR group). In both groups, postoperative EDV, SV and EF tended to increase, while ESV remained unchanged. In the OMC group, systolic wall motion of the left ventricle was found to be improved postoperatively, whereas systolic wall motion in the MVR group was found to be impaired postoperatively. The latter finding was assumed to be due to excision of the papillary muscles and chordae tendineae. Preservation of these structures is likely to be important for better postoperative functional recovery of the left ventricle.

Adult↗
PubMed1986

A role of the central catecholamine neuron in cerebral circulation.

The effect of the central catecholaminergic neurons on the cerebral microcirculation was investigated by means of a unilateral intracerebral injection of 6-hydroxydopamine (6-OHDA) which produced the degeneration of catecholamine (CA) nerve terminals. Subsequent observation with CA histofluorescence revealed an absence of CA fibers in the vicinity of the 6-OHDA injection site. A significant increase in regional cerebral blood flow (rCBF), measured by the hydrogen clearance method, was demonstrated in the CA-depleted cortex under normocapnia as compared with rCBF in the control cortex (CA-depleted cortex 47.0 +/- 2.8 ml/100 gm/min; control cortex 38.5 +/- 3.5 ml/100 gm/min; p less than 0.005). The increased rCBF in the cortex treated with 6-OHDA was suppressed by the iontophoretic replacement of noradrenaline (NA) to the CA-depleted cortex. An iontophoretic replacement of 10(-5) M dopamine (DA) mildly suppressed the increased rCBF in the 6-OHDA-treated cortex. The CO2 reactivity in the CA-depleted cortex was significantly lower than that of the control cortex (CA-depleted cortex 2.13% +/- 0.6%/mm Hg; control cortex 3.53% +/- 0.70%/mm Hg). No change was noticeable in the cerebral glucose metabolism in the CA-depleted cortex in an investigation based on tritiated (3H)-deoxyglucose uptake. It is suggested that the 6-OHDA-induced change in cerebral blood flow (CBF) is not secondary to alterations in cerebral metabolic rate, and that the central NA neuron system innervating intraparenchymal blood vessels regulates CBF through a direct vasoconstrictive effect on the cerebral blood vessels. The central DA neuron system may modulate the cerebral circulation as a mild vasoconstrictor.

Animals↗
PubMed1986

[Conditions of the primary culture for rat hepatocytes and plasminogen activator release].

The conditions of primary culture for rat hepatocytes was investigated on the releasing effect of Plasminogen Activator (PA). The culture method using Collagen Coated Dish (CCD-method) which is currently available and the ordinary culture method using Plastic Culture Dish (PCD-method) were employed for that purpose in a comparative way. The effect of the addition of some supplements, that is FN, Aprotinin, EGF were also investigated. The following results were obtained. The dissociated rat hepatocytes formed a monolayer with pavementlike morphology at 24-48 hours after seeding. No difference was observed in the morphology of hepatocytes during the culture period between the two methods, although CCD-method allowed 120 hours culture, whereas PCD-method allowed 72 hours. The PA activity was demonstrated on the hepatocytes by either culture method according to the fibrinolysis autography. The cultured hepatocytes released PA into the medium continuously as long as the viability and morphology of the cells were maintained in good state. The PA activity reached the maximum after 96 hours culture in CCD-method, whereas it reached the maximum after 48 hours in PCD-method. The addition of Aprotinin to the culture medium was not necessary for PA release in CCD-method in contrast to PCD-method. When EGF was discontinued in the culture medium, the release of PA was reduced in association with the occurring of morphological disintegration of hepatocytes.

Animals↗
PubMed1986

Pupillary responses evoked by electrical stimulation of area pretectalis in cats.

Pupillary responses evoked by electrical stimulation of the area pretectalis and neighboring midbrain structures were studied in the cat. The pupillary responses evoked were recorded using an infrared pupilloanalyzing system. Bilateral pupillary constriction was evoked with a low threshold current intensity by stimulation of the nucleus pretectalis medialis, nucleus pretectalis olivaris, rostral part of the nucleus pretectalis posterior, the most rostral part of the periaqueductal grey and the nucleus of posterior commissure. Bilateral pupillary dilation was induced with a low threshold current intensity by stimulating the nucleus pretectalis anterior, caudal periaqueductal grey and the midbrain tegmentum. The effects of changing stimulus intensity and stimulus frequency were also studied.

Animals↗
PubMed1985

Turnover of fibrinopeptide A (FPA) in rabbits.

FPA disappeared from the circulating blood along a double-exponential decay curve consisting of an initial phase (t 1/2 = 1.8 min) and a late phase (t 1/2 = 34.7 min). The rapid decrease in blood FPA was due to the large extravascular space, the size of which was estimated to be about 5 times larger than that of intravascular space. The actual amounts of 125I-FPA distributed to the organs and tissues were generally quite low. However, in the case of the urine, the injected amount of FPA was excreted at the rate of 50% per hour. Thus, the urinary FPA levels may reflect the occurrence of intravascular coagulation.

Animals↗
PubMed1985

Distribution of GABA-T-intensive neurons in the rat hindbrain.

The pharmacohistochemical method previously used to identify the distribution in rat brain of gamma-aminobutyric acid transaminase (GABA-T)-intensive neurons has been applied to the rat pons and medulla. The method involves systemic administration of the irreversible GABA-T inhibitor Gabaculine and the detection, 12 to 15 hours after the injection of the newly synthesized GABA-T by histochemical means. GABA-T-intensive neurons were found to be rich in the following hindbrain structures: inferior colliculus, nuclei of the raphe system, nuclei parabrachialis dorsalis and ventralis, nucleus cuneiformis, nucleus vestibularis medialis, nucleus tractus spinalis nervi trigemini, nucleus vagus, nucleus cochlearis, nucleus reticularis lateralis, nucleus ambiguus, nucleus cuneatus lateralis, inferior olive, and reticular formation of the pons and medulla. Neurons of the deep cerebellar nuclei and the rostral portion of the lateral vestibular nucleus were negative for GABA-T but were surrounded by granular staining indicative of impinging GABA-T-rich nerve endings. These results provide further support for the hypothesis that GABA neurons are far more GABA-T-intensive than other neurons in the central nervous system.

4-Aminobutyrate Transaminase↗
PubMed1985

Direct plasma injection method for the analysis of tryptophan metabolites by high-performance liquid chromatography coupled with precolumn deproteinization.

Reversed-phase HPLC method by direct plasma injection has been developed for the analysis of major tryptophan metabolites (both metabolites in kynurenine pathways and in indole pathways). Two columns were used: one was a short precolumn of protein-coated octadecylsilane (ODS) for deproteinization and also for trapping of tryptophan metabolites, and the other was an analytical column of the usual ODS. By a column-switching method, the metabolites trapped in the precolumn were allowed to be eluted through the analytical column. The recovery of the spiked metabolites in plasma by the present method was almost quantitative (98-102%) with good reproducibility (CV less than 3%, within-run), and the method is determined to be simple and reproducible for the analysis of total (free + protein-bound) tryptophan metabolites in plasma. The analysis of rabbit plasma showed several peaks corresponding to kynurenine, kynurenic acid, 5-hydroxyindole-3-acetic acid, indole-3-lactic acid, indole-3-acetic acid, indole-3-propionic acid, and 5-hydroxy-tryptamine in addition to tryptophan.

Chromatography, High Pressure Liquid↗
PubMed1985

Differential counts by electron microscopy of cell types in normal intimal cell masses in swine abdominal aortas.

Hyperlipidemic diet-induced atherosclerotic lesions show a predilection for locating at the site of normal collections of intimal cells in the swine abdominal aorta. This implies that preexisting intimal cell masses (ICM) evolve into early diet-induced lesions. This study characterizes in detail the distal abdominal aortic ICM of young normal swine as a basis for a better understanding of lesion development. Seventeen male Yorkshire swine were used, from neonates to 20 weeks of age. Only three of six neonates showed multilayered ICM, the remaining three showed scattered individual cells or a single layer of cells. All older swine had multilayered ICM at a predictable ventral site corresponding to Evans blue in vivo staining. The majority of cells counted by electron microscopy were smooth muscle (89 to 94%), the remaining were macrophages (1 to 8%) and poorly differentiated cells (3 to 5%). Weanling and older swine showed high proportions of contractile smooth muscle cells. Ergastoplasm-rich smooth muscle cells comprised nearly half of the neonatal population. Stainable lipids were demonstrable in 20-week-olds, but not in younger swine. No foam cells were seen, but cells containing a few droplets totaled 2%; macrophages comprised a high proportion of these. Pyknotic dead cells were rare, being found in the neonate and 20-week-old swine. Mitoses were observed in two ergastoplasm-rich smooth muscle cells in the neonate and one each in contractile smooth muscle cells of a 14- and a 20-week-old swine. Saddlebag-shaped, atypical-appearing cells were present in all age groups, involving all three cell types, and ranging from 1 to 3%. These represented either bridged nuclei and cytoplasm or more likely artefactual distortion of relatively normal cells.

Animals↗