Search PubMed⌕ Search

Biomedical subjects

T Morimoto

Publications and source records attributed to T Morimoto.

At least 379 records · Page 21Linked to original sources
PubMed1994

Impaired spatial learning by vasoactive intestinal peptide in Morris water maze task in the rat.

Intracerebroventricular administration of vasoactive intestinal peptide (VIP) disturbed the learning by rats of the location of a platform submerged in a water pool. When the platform was removed from the pool, VIP injection produced marked impairment of the ability to find a previously learned location in the pool. This spatial memory impairment caused by VIP was restored by peripheral pre-administration of cerulein.

Animals↗
PubMed1994

In vivo visualization of oxygen transport in microvascular network.

Oxygen transport from the blood to the tissues is a diffusive process driven by the gradient of oxygen tension (PO2). We developed an oxygen-quenching fluorescent membrane that allowed visualization of the PO2 distribution near the microvessels as optical patterns on the membrane by epifluorescence microscopy. This membrane was highly gas permeable to allow PO2 measurement and was transparent enough to also permit observation of the microcirculation. In combination with a newly devised gastight chamber and a micropositioning system, this membrane technique made it possible to visualize the PO2 distribution in the rat mesenteric microvascular network under well-defined conditions. Our preliminary findings indicate that the oxygen distribution in the microvascular network is heterogeneous and suggest that there is considerable release of oxygen from the arterioles. The time lag of the system for tracking rapid PO2 changes in vitro was shown to be negligible, indicating that dynamic PO2 changes occurring in vivo can also be assessed. This technique should provide a novel tool for the study of oxygen transport and metabolism under normal and abnormal conditions.

Animals↗
PubMed1994

Right atrial pressure and ANP release during prolonged exercise in a hot environment.

To investigate the relationship between right atrial pressure (RAP) and atrial natriuretic peptide (ANP) release during prolonged exercise in a hot environment (30 degrees C, 20% relative humidity), we studied with a Swan-Ganz catheter five male volunteers exercising on a cycle ergometer at 60% of peak aerobic power for 50 min. The ANP level increased from 14 +/- 3 (SE) to 69 +/- 10 pg/ml (P < 0.001) during the first 10 min of exercise as RAP rose from 4.3 +/- 0.8 to 6.9 +/- 1.1 mmHg (P < 0.001). The 10-min ANP level was significantly correlated with RAP (r = 0.88, P < 0.05) but not with heart rate, pulmonary arterial blood temperature, plasma norepinephrine, or plasma epinephrine. The 10-min RAP value was inversely correlated with blood volume (r = -0.98, P < 0.01) and also with stroke volume (r = -0.96, P < 0.01). In the next 20 min of exercise, ANP continued to increase to 101 +/- 12 pg/ml (P < 0.02 vs. 10 min) and remained at this level until 50 min of exercise, whereas RAP decreased and reached a level not significantly different from baseline at 50 min (5.7 +/- 1.0 mmHg; P < 0.01 vs. 10 min). This dissociation of ANP and RAP may have been related to the significant increases from the 10-min values of heart rate, blood temperature, norepinephrine (all P < 0.01), and epinephrine (P < 0.02) during the same period. These results suggest that ANP release is primarily controlled by atrial distension at the onset of exercise but that other stimulators may be involved thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Hemodynamics and hepatic energy metabolism in canine model of acute hepatic venous occlusion with mesocaval shunt.

The relationship between portal hemodynamics and the energy metabolism of the liver with acute hepatic venous occlusion (HVO) was investigated by assessing the changes in the hepatic blood flow, arterial blood ketone body ratio (AKBR) and adenylate energy charge potential (ECP) of the liver tissue in canine model. Acute HVO was induced by the ligation of both the supra- and infrahepatic inferior vena cava (IVC) over the protruding ends of a heparin-coated polyethylene cannula inserted into the IVC. All dogs with only HVO (n = 5) died within 30 min. HVO dogs with additional mesocaval (MC) shunt (n = 10) survived longer than 7 days, during which time their AKBR were maintained in the normal range (over 1.0). ECP was also maintained above the normal level (over 0.850) during the 28-day period. Along with increasing portal pressure caused by the narrowing of the shunt anastomosis, the hepatic blood flow decrease gradually, resulting in a sudden decrease in AKBR and ECP when the portal pressure increased over 11 mm Hg. It is suggested that the normalization of portal pressure is one of the most important factors for maintaining the hepatic energy metabolism and that MC shunt is an effective therapy for maintaining the function of the liver with HVO, as long as portal pressure can be kept within normal range.

Animals↗
PubMed1994

Evaluating microscopic arterial reconstruction: a comparison of laser-assisted versus conventional vascular anastomosis in 70% hepatectomized rat model.

The influence of deteriorated liver function on the healing process of arterial anastomosis was investigated in rats who underwent arterial reconstruction by the microscopic surgical techniques of conventional sutured vascular anastomosis (CSVA) and laser-assisted vascular anastomosis (LAVA). After 70% hepatectomy, the arterial ketone body ratio, reflecting the hepatic mitochondrial redox state, and the adenylate energy charges of the platelets, polymorphonuclear leukocytes and mononuclear cells, which play an important role in wound healing, were significantly lower in hepatectomized rats than in control. Tensile strength and bursting pressure with CSVA at the abdominal aortic anastomosis were also significantly lower in hepatectomized rats than in control. While CSVA was superior to LAVA in tensile strength, bursting pressure and incidence of aneurysm formation in nonhepatectomized rats, LAVA tended to show a lower degree of disadvantage in hepatectomized rats than CSVA, especially in the incidence of calcification at the anastomotic site. It was concluded that LAVA would be a useful option in vascular anastomosis, even during extended hepatectomy.

Anastomosis, Surgical↗
PubMed1994

Influence of exercise intensity and plasma volume on active cutaneous vasodilation in humans.

The influence of dynamic exercise on active cutaneous vasodilation was evaluated in eight male subjects. We measured the increase in internal body temperature (esophageal temperature, Tes) required to elicit active cutaneous vasodilation and the slope of the linear relationship between increases in forearm skin vascular conductance (delta FVC) and Tes during indirect heating (legs immersed in 44 degrees C water for 30 min), 30 min of light exercise (LEX; 75 +/- 5 W = 30% maximal oxygen uptake, VO2max), and 20 min of moderate exercise (MEX, 149 +/- 7 W = 60% VO2max). Studies were conducted in the supine position at 30 degrees C (RH < 30%) and mean skin temperature averaged 35.09 +/- 0.12 degrees C. During indirect heating and LEX, cutaneous vasodilation occurred after a similar increase in Tes, 0.03 +/- 0.02 degrees C and 0.11 +/- 0.02 degrees C, respectively. During MEX, Tes increased 0.42 +/- 0.06 degrees C before the onset of cutaneous vasodilation (P < 0.05, different from rest and LEX). The relationship between the increase in Tes threshold for vasodilation and exercise intensity was nonlinear, indicating that some minimal exercise intensity was required to elicit a delay in active cutaneous vasodilation. That minimal exercise intensity was greater than 30% VO2max (75 +/- 5 W). During MEX the increase in Tes threshold for vasodilation was inversely related to resting plasma volume (ml.kg-1) with a larger initial plasma volume associated with a smaller increase in Tes threshold for cutaneous vasodilation (r2 = 0.67, P = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Application of electrical impedance analysis for diagnosis of a pulmonary mass.

The electrical impedance of a pulmonary mass was measured in 53 patients of whom 44 had primary lung cancer, 5 had metastatic lung tumor, and 4 had organizing pneumonia. Because biologic tissue can be regarded, electrically, to consist of extracellular resistance (Re), intracellular resistance (Ri), and the electrical capacitance of the cell membrane (Cm), these three parameters were calculated from the measured electrical impedance of tissue by a curve-fitting technique using a computer program. The Re of lung tissue was significantly greater (p < 0.01) and the Cm of lung tissue was significantly less (p < 0.01) than that of a pulmonary mass. The Re of malignant tumors (both lung cancer and metastatic tumors) was significantly greater (p < 0.01) and the Cm of malignant tumors was significantly less (p < 0.01) than that of organizing pneumonia. With this information, we used a biopsy needle to diagnose nine intrathoracic lesions. This technique additionally allowed us to confirm the proximity of the needle tip of the mass. The electrical impedance of the lung mass was measured through the biopsy needle using a modified impedance analysis system before the biopsy was performed. There were no false-negative results, and one false-positive result. The rapid measurement of the electrical impedance of a pulmonary mass, preoperatively, may be of value in the clinical evaluation of a pulmonary mass both by facilitating needle guidance and by permitting diagnosis based on electrical impedance.

Aged↗
PubMed1994

Switching of mouse spermatogonial proliferation from the c-kit receptor-independent type to the receptor-dependent type during differentiation.

Testicular cells composed mostly of germ cells and immature Sertoli cells from neonatal mice 2 and 5 days old were cultured to investigate germ-cell proliferation mediated by the c-kit receptor. The addition of antibody to block the interaction of the c-kit receptor with its ligand inhibited the proliferation of cultured spermatogonia from 5-day-old mice in a dose-dependent manner, but not from that of 2-day-old mice. The addition of anti-c-kit ACK2 monoclonal antibody also inhibited the proliferation of spermatogonia from 5-day-old mutant Sld/Sld mice but not of 5-day-old mutant Wv/Wv mice. The results indicate that c-kit-positive type A spermatogonia in the testes of 5-day-old mice require steel factor (kit ligand) for their proliferation, whereas self-renewal and differentiation of c-kit-negative primitive type A spermatogonia in the testes of 2-day-old mice do not.

Animals↗
PubMed1994

Open-field behavior of rats following intracerebroventricular administration of neuromedin B, neuromedin C, and related amphibian peptides.

Neuromedin B (NMB) and neuromedin C (NMC) have amino acid sequences similar to those of various amphibian skin peptides and thus may elicit behavioral effects similar to those of bombesin. The present study was performed to determine the central effects of neuromedins (including pyro-NMB and pyro-NMC) in comparison with those of amphibian peptides using an open-field test situation. At 1 min after intracerebroventricular administration of the peptides, there was a marked decrease in the duration of locomotion, the distance moved, and rearing behavior, but a marked increase of excessive grooming and violent scratching. Pronounced behavioral changes were still observed 30 min after injection of the peptides, except for NMB. Thus, NMB seemed to be rapidly degraded by endogenous peptidases in the brain, suggesting that it might be the essential form of this neuropeptide family in the mammalian brain.

Amino Acid Sequence↗
PubMed1994

Medulloblastoma associated with cysts and calcifications--case report.

An 11-year-old boy presented with medulloblastoma occurring in the cerebellar vermis. Computed tomography and magnetic resonance imaging revealed numerous cysts and calcifications in the tumor. The tumor was subtotally removed and cellular synchronization radiation therapy given. He was discharged without neurological deficits. Histological examination showed the cysts represented necrotic foci. Macrophages, which appeared around the necrotic foci, were important in the development of the calcifications via proliferation of collagen fibers.

Brain↗
PubMed1994

Pleomorphic adenoma of the lacrimal gland manifesting as exophthalmos in adolescence--case report.

A 16-year-old girl presented with a pleomorphic adenoma of the lacrimal gland manifesting as left painless exophthalmos which had persisted for 3 years. Computed tomography revealed a tumor about 15 mm in diameter in the superolateral site of the left orbit. The tumor was removed completely by combined orbitofrontal craniotomy through a transcranial approach. Histological examination demonstrated the growth of tumor cells as glandular cavities or sheets, with myxoid and partly chondroid connective tissue stroma. Pleomorphic adenoma of the lacrimal gland is unusual in adolescents.

Adenoma, Pleomorphic↗
PubMed1994

Strategies to improve the outcome of carotid endarterectomy.

The outcomes of carotid endarterectomy (CEA) including long-term results in 121 patients (126 procedures) were retrospectively analyzed to identify the causes of operative morbidity. The angiographic internal carotid artery (ICA) stenosis was severe (> 70%) in 62 patients and moderate (50-70%) with ulceration in 64. The arterial wall was sutured primarily in 91 patients and with patch graft in 35. The outcomes 3 months after operation were good recovery in 86 patients, moderately disabled in 20, severely disabled in 11, and death in four. Three patients suffered operative morbidity (2.5%). During follow-up, three patients (2.6%) suffered transient ischemic attack on the operative side due to middle cerebral artery stenosis (50%) or ICA occlusion at the origin, and recurrent stenosis (40%) of the common carotid artery and ICA (1 each). In the latter two cases, the artery was primarily sutured. Improved therapeutic results require use of patch vein graft for the arterial wall suture, checking of the CEA patency, and prevention of intracranial ischemic events and hemorrhage due to associated lesions.

Adult↗
PubMed1994

Evaluation of hepatic function.

Nine articles published since January 1992 on new methods of evaluating hepatic function are reviewed. These articles described the clinical significance of blood levels of cytokines, fibrin- or fibrinogen-related antigens, vitronectin, and endothelin, and of magnetic resonance spectroscopy, methionine metabolism, vasopressin clearance, vascular compliance, and radioreceptor imaging in gastroenterology. None of the methods have yet been applied to surgery. In addition, the redox theory, the evaluation of hepatic mitochondrial redox potential by arterial ketone body ratio and its clinical application, is introduced, and recent publications on the assessment of graft viability in liver transplantation and preoperative hepatic functional reserve in liver surgery based on the theory are reviewed.

Critical Care↗
PubMed1994

[A case-report of pacemaker malfunction caused by dry pocket after replacement of pulse generator].

Pacemaker malfunction was attributed to the increasing in impedance to current flow caused by a pocket of air separating the anodal contact plate of a unipolar generator from the overlying connective tissue (so-called dry pocket). Lack of capture was noted just after replacement of pulse generator. The malfunction was permanently corrected by bediside infusion of saline to pacemaker pocket.

Aged↗
PubMed1994

15 years of CPITN--a Japanese perspective.

In Japan CPITN has been widely applied in dentistry over the past 10 years. CPITN has been introduced for screening purposes into basic dental epidemiology, dental public health and dental clinical practice. From many surveys the periodontal needs of young, mature and elderly populations have been documented. For the purpose of promoting improved periodontal awareness and care, CPITN has been implemented in dental public health and community based activities in schools, in industry, and in health centres. This has involved periodontal screenings and appropriate health guidance. The Japanese Health Laws are being modified to include a need for periodic oral examinations which will incorporate a CPITN screening. National goals for periodontal health at different age levels, based on CPITN, have been proposed and included in the national '8020' goal for oral health.

Adolescent↗