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Biomedical subjects

T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 829 records · Page 46Linked to original sources
PubMed1991

Kinetic studies of growth hormone and prolactin during adaptation of coho salmon, Oncorhynchus kisutch, to different salinities.

The kinetics of growth hormone (GH) and prolactin (PRL) in coho salmon (Oncorhynchus kisutch) transferred from fresh water (FW) to seawater (SW) and vice versa were examined to help clarify the osmoregulatory roles of the two hormones during periods of migration to different salinities. Chum salmon GH or PRL was administered by a single injection intraarterially, and metabolic clearance rate (MCR) and secretion rate (SR) of injected hormones were calculated from the disappearance of the hormones from the plasma. When coho salmon smolts were acclimated to SW, MCR, SR, and plasma level of GH in SW-adapted (2-3 weeks) fish were twice as great as those in fish in FW. On the other hand, there was no difference in the kinetics of GH between the adult coho salmon in SW and those adapted to FW (2-3 weeks). The transfer of the adult coho salmon from SW to FW was followed after 2 days by a rise in plasma level and SR of PRL, which tended to stay at high levels after 2-3 weeks. The MCR of PRL increased significantly after 2-3 weeks in FW. These results support the likelihood of an important role of GH in SW adaptation and of PRL in FW adaptation in coho salmon.

Adaptation, Physiological↗
PubMed1991

Total synthesis of a gene for octopus rhodopsin and its preliminary expression.

To carry out systematic structure-function studies of octopus rhodopsin, photoreceptor protein of octopus visual cells, by means of specific amino-acid replacements, we have totally synthesized a DNA duplex of 1,365 base pairs that encodes the entire octopus rhodopsin of 455 amino acids [Ovchinnikov et al. (1988) FEBS Lett. 232, 69-72] by introducing codons preferred in Escherichia coli. Total synthesis simplifies site-specific mutagenesis in all parts of the gene by replacement of short restriction fragments by their newly synthesized counterparts containing the required nucleotide alterations. Thirty unique restriction sites were introduced in the octopus rhodopsin gene, which was assembled on a plasmid in two steps. Five cartridge genes of 344, 296, 320, 212, and 317 base pairs capable of being expressed independently were first constructed by using 48 synthetic oligonucleotides ranging in size from 54 to 73 nucleotides. The entire gene was constructed by consecutive linkage of cartridge genes. These cartridge genes were designed to correspond to the transmembrane helical unit of octopus rhodopsin, resulting in easy construction of various chimeric rhodopsins. The nucleotide sequences were confirmed by sequencing the cartridges as well as the entire gene. These synthetic genes were cloned into an expression vector carrying the trp promoter of E. coli, and were preliminarily expressed in vitro and in vivo.

Amino Acid Sequence↗
PubMed1991

Application of mathematical model to multiple-dose experimental chemotherapy for fatal murine pneumonia.

Two beta-lactam antibiotics, cefazolin and cefmenoxime, were administered for 7 days to mice with pneumonia caused by Klebsiella pneumoniae by using dosage regimens that would simulate multiple dosing in usual clinical treatments at dosing intervals of 8 or 12 h. Viable numbers of the bacteria in the lungs were measured at 12- or 24-h intervals. The mathematical model established in a previous single-dose study was applied in this study to explain the time courses of the changes in bacterial count over 7 days. However, because the error in viable count measurements was larger than that in the previous study, the time course of the changes in mean viable count was not regular and the viable count reduction rate changed during multiple dosing, and therefore it was difficult to explain the time course by repeated application of the mathematical model described previously. This study suggests that the changes in pharmacokinetic and pharmacodynamic parameters during multiple dosing need to be considered.

Animals↗
PubMed1991

Toxicity and toxins of natural blooms and isolated strains of Microcystis spp. (Cyanobacteria) and improved procedure for purification of cultures.

All samples of cyanobacterial blooms collected from 1986 to 1989 from Lake Kasumigaura, Ibaraki Prefecture, Japan, were hepatotoxic. The 50% lethal doses (LD50s) of the blooms to mice ranged from 76 to 556 mg/kg of body weight. Sixty-eight Microcystis cell clones (67 Microcystis aeruginosa and 1 M. viridis) were isolated from the blooms. Twenty-three strains (including the M. viridis strain) were toxic. However, the ratio of toxic to nontoxic strains among the blooms varied (6 to 86%). Microcystins were examined in six toxic strains. Five toxic strains produced microcystin-RR, -YR, and -LR, with RR being the dominant toxin in these strains. Another strain produced 7-desmethylmicrocystin-LR and an unknown microcystin. This strain showed the highest toxicity. Establishment of axenic strains from the Microcystis cells exhibiting extracellularly mucilaginous materials was successful by using a combination of the agar plate technique and two-step centrifugation.

Animals↗
PubMed1991

Immunohistological and electron microscopical study of nodular fasciitis of the orbit.

We report the case of a 7-year-old Japanese girl with nodular fasciitis which was investigated by immunohistological and electron microscopical methods. An excised nodular lesion in her right orbit showed characteristic histological features of the disease. The fibroblastic cells showed myofibroblastic characteristics, such as immunohistochemically positive reactions against muscle specific actin and vimentin and characteristic electron microscopical appearances. The multinuclear giant cells did not react against any histiocytic markers, including HLA-DR, antimacrophage antigen, lysozyme, and S-100 protein, but the myofibroblastic markers and the electron microscopical study did reveal myofibroblastic characters.

Child↗
PubMed1991

Extracellular phospholipase A2 and histamine release from rat peritoneal mast cells.

Phospholipase A2 (PLA2) from cobra (Naja naja) venom and PLA2 from porcine pancreas accelerated IgE antibody-mediated histamine release from rat peritoneal mast cells. These enhancements were clearly abrogated by heating the enzymes and pretreatment with parabromophenacyl bromide, mepacrine and antiflammin. Indomethacin (cyclooxygenase inhibitor) and AA-861 (lipoxygenase inhibitor) did not affect the enhancement by PLA2. These results indicate that extracellular PLA2 enhances the IgE antibody-mediated histamine release from rat peritoneal mast cells without the participation of arachidonate.

Animals↗
PubMed1991

Osmoregulatory actions of insulin-like growth factor-I in rainbow trout (Oncorhynchus mykiss).

The ability of insulin-like growth factor-I (IGF-I), insulin and GH to promote hypoosmoregulatory ability was examined in juvenile rainbow trout (Oncorhynchus mykiss). Following adaptation to 12 parts per thousand (p.p.t.) seawater for 5 days, fish were given a single injection of hormone or vehicle, then exposed to 29 p.p.t. for 24 h and examined for changes in plasma osmolarity, ions and glucose. Ovine GH (oGH; 0.2 micrograms/g) significantly improved the ability of rainbow trout to maintain plasma osmolarity and sodium levels following transfer to 29 p.p.t. seawater. Recombinant bovine IGF-I (0.01, 0.05 and 0.02 micrograms/g) also improved the hypoosmoregulatory ability of trout; the effect being dose-dependent and greater than that of oGH. Bovine insulin (0.01, 0.05 and 0.2 micrograms/g) had no statistically significant effect on plasma ions. The results indicate that IGF-I is a potential mediator of the action of GH in seawater adaptation of salmonids.

Adaptation, Physiological↗
PubMed1991

Growth hormone receptors in the liver and osmoregulatory organs of rainbow trout: characterization and dynamics during adaptation to seawater.

Specific binding sites for chum salmon growth hormone (sGH) were identified in the membranes obtained from tissues of rainbow trout. Specific binding of 125I-labelled sGH (% per mg protein) was found in the liver (37%), ovary (6%), brain (6%), gill (4%), intestine (4%) and posterior body kidney (4%). Specific binding was not significant in head kidney, anterior body kidney, spleen, heart, skeletal muscle or skin. Scatchard analyses demonstrated the presence of a single class of high-affinity low-capacity receptors in the liver, gill, intestine and kidney. The association constants for the membranes from liver, gill, intestine and kidney were of the same order (1 litre/nmol). Chum salmon prolactin did not inhibit the binding of 125I-labelled sGH to receptors in the liver, gill, intestine and kidney. Transfer of rainbow trout from fresh water to 80% seawater evoked a rise in plasma concentration of GH and a significant decrease in the GH binding to the liver membranes after 1 day. Binding in the gill and kidney was not altered significantly. Membranes were treated with 4 mol MgCl2/l to remove bound GH from the receptors, and the results indicated that the reduction in binding in the liver after transfer to seawater was probably due to receptor occupancy by increased endogenous GH. The occupancy of liver GH-binding sites was maximal 4 days after transfer. Total (MgCl2-treated) binding sites in the liver increased significantly 14 days after transfer. Scatchard analysis indicated that receptors were altered in capacity without changes in binding affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1991

[Efficacy of preoperative irradiation in midline oligodendrogliomas. Report of two cases].

Two midline oligodendrogliomas in young males were successfully totally removed after preoperative irradiation. A 33-year-old male with right lower extremity weakness had a large hypervascular mass occupying the left lateral ventricle. Even after 31 Gy whole-brain irradiation, massive bleeding occurred at surgery and resulted in only partial removal. The residual tumor markedly regressed with disappearance of abnormal vascularity after subsequent local boost irradiation. At the second operation, the tumor was totally removed. A 32-year-old male with progressive headache had a hypervascular mass with gross calcification in the right lateral ventricle. The tumor was partially resected due to its abundant vascularity and blood loss. After 60 Gy local irradiation, the tumor was moderately shrunk with a significant reduction in vascularity. At the second operation, the tumor was totally removed. Preoperative irradiation as an adjunct to surgery may increase the resectability of highly vascular tumors such as midline oligodendrogliomas.

Adult↗
PubMed1991

[The coefficient of variation of RR intervals (CVRR) on electrocardiogram in patients with essential hypertension with reference to aging, hemodynamics and sympatho-adrenomedullary function].

To evaluate the significance of parasympathetic nerve activity in essential hypertension, we measured the coefficients of variation of RR intervals (CVRR) on electrocardiogram and examined the relationships between CVRR and aging, hemodynamics and sympatho-adrenomedullary function in normotensive subjects (NT) and in patients with essential hypertension (EHT). Mean arterial pressure (MAP), heart rate (HR), plasma noradrenaline concentration (pNA), plasma adrenaline concentration (pAd) and CVRR resting in a supine position were simultaneously measured in 37 NT (33.8 +/- 2.0 years) and 47 mild-to-moderate EHT (51.3 +/- 1.5 years). In both NT and EHT, significantly negative correlations between CVRR and age (NT: r = -0.54, p less than 0.001, EHT: r = -0.41, p less than 0.005) were observed, however, CVRR correlated with neither MAP, HR nor pAd. CVRR tended to correlate negatively with pNA (r = -0.27, p less than 0.1) in NT, unlike in EHT. The mean value of CVRR in EHT (n = 10, age: 38.3 +/- 1.6 years, CVRR: 3.61 +/- 0.37%) was significantly (p less than 0.005) lower than in age-matched NT (n = 10, age: 38.3 +/- 2.5 years, CVRR: 5.76 +/- 0.45%). These results indicate that the parasympathetic tone suggested by CVRR may be related to aging and sympathetic nerve activity, and that parasympathetic function might be impaired in EHT.

Adolescent↗
PubMed1991

[Separation of high density lipoprotein (HDL) using anti-apo A-I, apo A-II immuno-affinity chromatography to evaluate the effects of probucol].

An assessment has been made regarding the changes of the particles of lipoprotein A-I without A-II (Lp A-I) and lipoprotein A-I with A-II (LpA-I/A-II) which correspond to HDL subfraction isolated by the use of anti-apo A-I and A-II antibody affinity columns in order to quantitatively and qualitatively investigate the change of HDL caused by administration of probucol and pravastatin which are therapeutic drugs for hypercholesterolemia. Probucol caused significant decreases of HDL-cholesterol, plasma apo A-I/apo A-II ratio and particles larger in diameter than 10.4 nm. Comparing Lp A-I and A-I/A-II ratios with those in normolipidemic controls and the ratios before and after administration of probucol, the decrease of LpA-I ratio was found to be remarkable after prolonged administration of probucol, and it was presumed that the decrease of HDL cholesterol by prolonged administration reflects the decrease of LpA-I particles more than the decrease of LpA-I/A-II. On the other hand, no significant change was seen in HDL cholesterol, plasma apo A-I/apo A-II ratio or HDL particle size in the pravastatin group. It is considered essential to observe HDL from the aspect of apoprotein, which plays an important role in the metabolism of lipoprotein, in the assessment of the anti-atherogenic activity of HDL cholesterol in future. In other words, it is necessary to analyze the change of HDL from the aspect of Lp A-I and Lp A-I/AII and investigate their respective metabolisms and roles.

Adult↗
PubMed1991

[Shy-Drager syndrome: its autonomic function, alpha 2 receptor density and mechanism of postprandial hypotension].

The autonomic function, platelet alpha 2 receptor (alpha 2R) density, and mechanism of postprandial hypotension were examined in a 58-year-old man with Shy-Drager syndrome (SDS). His chief complaints were orthostatic syncope and impotence. His blood pressure was kept within normal limits in a supine position, but severe hypotension and fainting occurred when he assumed an upright posture. There were diminished sweating response to warm stress, abnormal pupil reactions to drugs, lack of blood pressure elevation at phase IV during the Valsalva maneuver, and a lack of pressor response to hyperventilation and cold stress. The plasma norepinephrine levels (pNE) were very low in a supine position at rest and in a head-up tilt position. Severe blood pressure fall (hypotension) associated with a lack of pNE elevation occurred during an oral glucose tolerance test (oGTT). Platelet alpha 2R density increased and the pressor response to infused norepinephrine (NE-R) was pronounced. The heart rate response to injected atropine was clearly attenuated. The coefficient of the R-R interval variation in the ECG (CVRR), which may reflect parasympathetic activity, was markedly low at rest. In addition, a decrease in a head-up tilt position and increase during oGTT also resolved. These results indicate that a dysfunction of the parasympathetic and sympathetic nervous systems and the up-regulation in the alpha 2R system that leads to an increase in alpha 2R density in SDS are involved in this disease and that the mechanism of postprandial hypotension in SDS may be different from that in normal elderly subjects.

Atropine↗
PubMed1991

Fc epsilon receptor II/CD23-positive lymphocytes in atopic dermatitis. I. The proportion of Fc epsilon RII+ lymphocytes correlates with the extent of skin lesion.

Cells expressing Fc receptors for IgE (Fc epsilon RII) were identified in the peripheral blood from patients with atopic dermatitis and with eczematous dermatitis, and normal non-atopic subjects by using monoclonal antibodies to human lymphocyte Fc epsilon RII, and to lymphoid cell-surface antigens by immunofluorescence staining. Based on the extent of the dermatitis patients were classified as severe (greater than 50% skin surface involved), moderate (50-10%) and mild (less than 10%). Patients with severe and moderate atopic dermatitis had 5.9% and 5.7% Fc epsilon RII+ peripheral blood mononuclear cells (PBMC), respectively, that were significantly higher than percentages in mild atopic dermatitis patients (2.6%), severe to moderate eczematous dermatitis patients (2.3%), mild eczematous dermatitis patients (2.2%) and normal individuals (1.7%)(0.05 greater than P). In severe and moderate atopic dermatitis patients, 10% of Fc epsilon RII+ PBMC were T cells that preferentially expressed CD8, and the remainder B cells and monocytes. Fc epsilon RII+ T cells comprised 1% of peripheral T cells, while half or more of peripheral B cells expressed Fc epsilon RII. In mild atopic dermatitis patients, eczematous dermatitis patients and normal subjects. Fc epsilon RII were expressed exclusively on 25-35% of peripheral B cells. Short-term treatment and long-term follow-up of atopic dermatitis patients revealed that changes in the skin condition were related closely to fluctuations in the proportion of Fc epsilon RII+ PBMC. Total serum IgE levels and atopic respiratory allergy did not influence the percentage of Fc epsilon RII+ PBMC. These findings suggest that the percentage of Fc epsilon RII+ PBMC reflects the extent of atopic dermatitis.

Adolescent↗
PubMed1991

[Allergenic relationships between Aspergillus restrictus and Aspergillus fumigatus determined by radioallergosorbent test inhibition].

Recently Aspergillus restrictus, a species of osmophilic fungi, has been found to be widely distributed in our inhabited environment. The authors reported previously that the prevalence of hypersensitivity to this fungal species determined by skin prick test and radioallergosorbent test (RAST) was comparable with that to Aspergillus fumigatus. In this study, the allergenic relationships between the two fungi were examined by RAST and RAST inhibition tests in which A. restrictus extracts prepared from mycelial mats of two different strains cultured in M40Y liquid medium and A. fumigatus, one made from a mycelial mat cultured in YNB liquid medium containing 3% sucrose, were used. In the RAST inhibition tests using a serum pool obtained from five patients with highly positive RAST to these species, the two extracts of A. restrictus inhibited RAST to A. fumigatus by over 80%, and A. fumigatus extract inhibited RAST to the two strains of A. restrictus by approximately 75%. In A. fumigatus RAST inhibition tests using individual sera with positive A. fumigatus RAST, a strong inhibition (greater than 60%) elicited by each extract of A. restrictus was observed in 5 of 8 sera tested. In RAST, nine of 11 serum samples with positive RAST to A. fumigatus showed positive RAST to both strains of A. restrictus. There was a significant correlation between the RAST values of the two fungal species. These results give evidence of the presence of shared allergenic components between the two fungi, and indicate that these components may contain part of major allergens of A. fumigatus.

Adolescent↗
PubMed1991

[Clinical features of main and peripheral pulmonary artery stenosis: significance of auscultation and phonocardiography].

Twenty-five patients with main and peripheral pulmonary artery stenosis were studied to determine the most frequently observed diagnostic sign of this abnormality regardless of the underlying etiologies, such as intrinsic or extrinsic narrowing of the pulmonary artery due to tumor, fibromuscular dysplasia, thromboembolism, angitis including the aortitis syndrome (Takayasu arteritis) and a variety of other disease entities. Among a variety of signs and symptoms, we emphasized the importance of cardiac auscultation and phonocardiography, which were often the initial diagnostic clues. The diagnostic features included a systolic murmur of pulmonary arterial origin and the behavior of the splitting of the second heart sound. The systolic murmur was often trans-systolic or continuous. In cases with left-sided cardiac murmurs (Takayasu arteritis, etc), the pulmonary systolic murmurs were not identified by auscultation alone and required phonocardiographic confirmation. In many cases the second heart sound was split and this was sometimes the first clue to the diagnosis. The split intervals varied, but were more marked in cases with pulmonary hypertension, and were accompanied by the accentuated pulmonic component (IIP). Phonocardiographic analysis disclosed that wide splitting was caused by the delayed appearance of IIP as well as the concomitant early appearance of the aortic component (IIA). It was concluded that, although the final etiological diagnosis is not identified, auscultation and phonocardiography provide important clues for further diagnostic and etiological studies of pulmonary artery stenosis.

Adolescent↗
PubMed1991

[Hematolymphoid system in the liver--restoring mechanism of hemopoiesis in the regenerating liver].

For the study of immunological phenomena peculiar to liver transplantation, it would be important to know well hematolymphoid system in the liver. In this paper, we report the restoring mechanism of hemopoiesis in the murine regenerating liver. 1) We found hemopoietic stem cells (HSC) and wheat germ agglutinin positive cells (WAG-PC) in both fractions of peripheral blood lymphocytes (PBL) and intrahepatic lymphocytes (IHL) from untreated C3H/He mice. The numbers of HSC and WGA-PC in each fraction gradually increased after partial hepatectomy. This change was remarkable in the population of IHL, associated more strongly with the liver. Colonies, which were generated from IHL in a fibrin clot culture system, are mainly composed of granulocytes, macrophages and mast cells. 2) We found colony-stimulating activity not only in the culture supernatant of normal nonparenchymal liver cells but in that of normal parenchymal liver cells. Furthermore, we clarified that one of colony-stimulating factors in both culture supernatants is GM-CSF. This result suggests parenchymal liver cells also release cytokines such as GM-CSF. These facts show that hematolymphoid system in the liver is a complicated network, composed of parenchymal liver cells, nonparenchymal liver cells, hemopoietic stem cells, and other cell populations.

Animals↗