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Biomedical subjects

M Kasai

Publications and source records attributed to M Kasai.

At least 361 records · Page 20Linked to original sources
PubMed1988

Effects of iontophoretically applied cortisol on tuberoinfundibular neurons in hypothalamic paraventricular nucleus of anesthetized rats.

Effects of cortisol on 22 tuberoinfundibular (TI) neurons in the paraventricular nucleus (PVN) of the hypothalamus were examined in urethane-anesthetized rats. Iontophoretically applied cortisol excited 10 (45%) of 22 TI-neurons tested, whereas the cortisol inhibited 4 (31%) of 13 neurons in the periventricular hypothalamic nucleus. Intravenously applied cortisol (0.5 mg in 0.5 ml saline) excited 4 (36%) of 11 TI neurons tested and inhibited 1 (9%). These results suggest that cortisol may have an excitatory effect on TI neurons in the PVN.

Action Potentials↗
PubMed1988

Atrial natriuretic polypeptide depresses angiotensin II induced excitation of neurons in the rat subfornical organ in vitro.

The effects of atrial natriuretic polypeptide (ANP) on the extracellularly recorded activity of neurons in the subfornical organ (SFO) were investigated in rat brain slice preparations by adding the peptide to the perfusion medium. Eight (14%) of 56 SFO neurons were inhibited and none of the cells were excited by ANP at 10(-7) M. Of 42 SFO neurons tested with both ANP and angiotensin II (AII) at 10(-7) M, 4 (10%) cells were inhibited by ANP and excited by AII, the remainder responded to either one or other of the peptides but not both or were unresponsive. In 13 (87%) of 15 SFO neurons, ANP at 10(-7) M depressed by more than 40% the excitation induced by AII at 10(-7) M, while ANP did not always depress the excitation induced by raising the extracellular potassium concentrations in 6 SFO cells tested. We conclude that ANP strongly depresses AII-induced excitation in all SFO neurons, although it has very weak inhibitory effects on spontaneous activity, thus ANP may act as a neuromodulator in the SFO.

Angiotensin II↗
PubMed1988

Gating behaviors of a voltage-dependent and Ca2+-activated cation channel of yeast vacuolar membrane incorporated into planar lipid bilayer.

A voltage-dependent and Ca2+-activated cation channel found in the vacuolar membrane of the yeast, Saccharomyces cerevisiae, was incorporated into planar lipid bilayer and its gating characteristics were studied at the macroscopic and single-channel levels. The open-channel probability at steady state, which was estimated by the macroscopic current measurement, gave a maximum value at -10 mV and decreased in a graded fashion as the voltage became more positive or more negative. The steady-state voltage dependence was explained by assuming two independent gates, which had different rate constants and opposite voltage dependence. The fast-responding gate opened when the voltage of the cis side (the side to which the vesicles were added) was made more negative and the slow-responding gate behaved in the opposite direction. Relatively high concentrations of Ca2+, about 1 mM, were required on the cis side for opening the slow gate in a voltage-dependent manner. DIDS increased the open-channel probability of the fast gate when added to the cis side, but was ineffective on the slow gate.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1988

Induction of calcium influx in immature T lymphocytes by anti-FT-1 monoclonal antibody.

The functional role of FT-1 antigen was investigated by measuring changes in intracellular [Ca2+]i after the addition of anti-FT-1 monoclonal antibody to murine T leukemic cells and embryonic thymocytes. Anti-FT-1 induced a rapid and sustained increase in cytosolic free [Ca2+]i and this effect was completely blocked by EGTA and La3+. These results suggest that FT-1 molecule is functionally associated with a plasma membrane calcium ion channel in embryonic thymocytes.

Animals↗
PubMed1988

Gibbs-Donnan ratio and channel conductance of Tetrahymena cilia in mixed solution of K+ and Ca2+.

A single cation-channel from Tetrahymena cilia was incorporated into planar lipid bilayers. This channel was voltage-independent and is permeable to K+ and Ca2+. In the experiments with mixed solutions where the concentrations of K+ and Ca2+ were varied, the single-channel conductance was found to be influenced by the Gibbs-Donnan ratio. The data are explained by assuming that the binding sites of this channel were always occupied by two potassium ions or one calcium ion under the present experimental conditions (5 mM-90 mM K+ and 0.5 mM-35 mM Ca2+) and these bound cations determined the channel conductivity.

Animals↗
PubMed1988

A patient with biliary atresia who died 28 years after hepatic portojejunostomy.

A patient who died of hepatic failure nearly 29 years after hepatic portojejunostomy is reported. His death may be attributed to several faults in treatment. From our experiences it can be said that biliary atresia is a curable disease, although liver-transplantation is required in some patients in whom hepato portoenterostomy is unsuccessful.

Adult↗
PubMed1988

Non-specific suppressor cells in murine bone marrow chimeras: their possible role in GVHD-associated immunodeficiency.

Suppressor cells against several mitogen-induced responses were detected in the spleen of murine bone marrow chimeras, regardless of intravenous (i.v.) or intrasplenic (i.s.) bone marrow transplantation (BMT). According to the time-course of the suppressor activity against Con A, PHA, and PWM, they were readily detected at 11-21 days after BMT and thereafter, either gradually decreased or remained at a plateau level. In contrast, the suppressor activity against the LPS-stimulated response increased at 39-52 days as compared to 24-34 days after BMT. Characterization studies of suppressor cells early (11-21 days) after BMT revealed that those in the i.v. and i.s. chimeras were composed of host-derived plastic dish adherent and/or anti-Thy 1.2 antibody-insensitive spleen cells in general. On the contrary, those in the i.v. and i.s. chimeras that possessed severer GVHD were mainly composed of host-derived plastic dish non-adherent spleen cells. Since the suppressor activity was higher in chimeras with severe graft-versus-host disease (GVHD) than in conventional chimeras, suppressor cells against the mitogen-induced responses may be related to the immunodeficiency associated with GVHD. Particularly, plastic dish non-adherent suppressor cells may closely relate to GVHD-associated immunodeficiency as compared with plastic dish adherent suppressor cells.

Animals↗
PubMed1988

Suppressor activity in the supernatant of T cell clones derived from chimeric mouse spleen cells.

The supernatant from cultures of T cell clones derived from (BALB/c----C3H/He) chimeras suppresses BALB/c anti-C3H/He or BALB/c anti-C57BL/6 MLRs. When we studied the alloantigen specificity of the suppressor activity in culture supernatant, we observed three types of the suppressor activity (i.e., the suppressor activity against BALB/c anti-C3H/He MLR, against BALB/c anti-C57BL/6 MLR, and against both MLRs) on day 3 after stimulation of the T cell clones with 20% crude IL2 and feeder cells. Since the alloantigen specificity fluctuated somewhat with time, we considered that a time-course study was needed to determine it correctly. We thought it unlikely that any IFN-gamma or PGE2 in the culture supernatant of the T cell clones would have mediated the suppression. Our results suggest that alloantigen specific and non-specific suppressor T cells exist in bone marrow chimeras. The former appears to play an important role in inducing and maintaining transplantation tolerance, while the latter seems to have a rather harmful effect upon chimeras.

Animals↗
PubMed1988

Studies on subtype "d" biliary atresia.

Nine cases of specific type (subtype d) biliary atresia were experienced at the Tohoku University Hospital and were classified into three groups on the basis of their clinical and pathological findings. Group 1 cases were defined as cases showing obstruction on the side of the hepatic duct and cystic dilatation, communicating with the gallbladder, in the common bile duct. Group 2 cases were those showing dilatation similar to Group 1, but measuring less than 20 mm, the dilated part being covered with thick connective tissue. Group 3 cases were those showing isolated dilatation in the common hepatic duct or the common bile duct and having no communication with the gallbladder. The postoperative course was good in Group 1 patients, while jaundice was prolonged in Group 2 patients. In Group 3, jaundice disappeared in one patient who died later, while the other patient showed recurrence of slight jaundice.

Bile Ducts↗
PubMed1988

Effects of silver ion on the calcium-induced calcium release channel in isolated sarcoplasmic reticulum.

Ag+-induced Ca2+ release in isolated sarcoplasmic reticulum (SR) was studied by the stopped flow method monitoring chlortetracycline fluorescence change. After improving the experimental procedure, the initial rate of Ca2+ release could be determined more precisely than before. Micromolar concentrations of Ag+ specifically enhanced Ca2+ efflux from heavy fraction of SR vesicles (HSR). This specific effect was referred to as Ag+-induced calcium release. The Ag+-induced Ca2+ efflux was activated by caffeine and ATP, but was inhibited by Mg2+ and procaine. Further, Ag+ enhanced the Ca2+-induced Ca2+ release over the whole range of Ca2+ concentrations, similarly to ATP. Parallel to Ca2+ efflux, Mg2+ efflux, measured by the same method, was also activated by Ag+. Choline permeability determined by the light scattering method was also activated by Ag+. The results suggest that Ag+ binds to the activation site of the Ca2+-induced Ca2+ release channel and opens the channel. The Ag+ binding site is different from the Ca2+ binding site but similar to the ATP binding site.

Adenosine Triphosphate↗
PubMed1988

Calcium release from isolated sarcoplasmic reticulum due to 4,4'-dithiodipyridine.

The effects of SH reagents on Ca2+ release from sarcoplasmic reticulum (SR) vesicles were examined by the tracer method using 45Ca2+. Among the various SH reagents tested, 4,4'-dithiodipyridine (PDS) was found to induce Ca2+ release most specifically from the heavy fraction of SR vesicles. Further, the following results were obtained. (i) PDS bound covalently to proteins in the SR membrane and induced Ca2+ release. (ii) The Ca2+ release was further enhanced by ATP and caffeine, but inhibited by procaine, ruthenium red and various divalent cations. (iii) PDS enhanced the Ca2+ release in the whole range of Ca2+ concentrations tested. (iv) Choline permeability was also enhanced by PDS. Further, the electrical conductance of the Ca2+-induced Ca2+ release channels was studied by incorporating them into lipid bilayers and it was found that PDS increased the probability of opening of the channels. These results suggest that PDS binds to certain SH groups of the Ca2+-induced Ca2+ release channels in the SR membrane and thus induces Ca2+ release.

Animals↗
PubMed1988

A cation channel for K+ and Ca2+ from Tetrahymena cilia in planar lipid bilayers.

The single-channel properties for monovalent and divalent cations of a voltage-independent cation channel from Tetrahymena cilia were studied in planar lipid bilayers. The single-channel conductance reached a maximum value as the K+ concentration was increased in symmetrical solutions of K+. The concentration dependence of the conductance was approximated to a simple saturation curve (a single-ion channel model) with an apparent Michaelis constant of 16.3 mM and a maximum conductance of 354 pS. Divalent cations (Ca2+, Ba2+, Sr2+, and Mg2+) also permeated this channel. The sequence of permeability determined by zero current potentials at high ionic concentrations was Ba2+ greater than or equal to K+ greater than or equal to Sr2+ greater than Mg2+ greater than Ca2+. Single-channel conductances for Ca2+ were nearly constant (13.9 pS-20.5 pS) in the concentrations between 0.5 mM and 50 mM Ca-gluconate. In the experiments with mixed solutions of K+ and Ca2+, a maximum conductance of Ca2+ (gamma Camax) and an apparent Michaelis constant of Ca2+ (K Cam) were obtained by assuming a simple competitive relation between the cations. Gamma Camax and K Cam were 14.0 pS and 0.160 mM, respectively. Single-channel conductances in mixed solutions were well-fitted to this competitive model supporting that this cation channel behaves as a single-ion channel. This channel had relatively high-affinity Ca2+-binding sites.

Animals↗
PubMed1988

[Basic and clinical studies on patients who have undergone autologous or allogeneic bone marrow transplantation].

Bone marrow transplantation (BMT) is now increasingly applied not only to hematologic disorders such as leukemias and aplastic anemia but also to some of solid tumors. We experienced ten cases of bone marrow harvest and six cases of autologous or allogeneic BMT during the period from June, 1986 to August, 1987. For autologous BMT cases, bone marrow cells were harvested and cryopreserved at -196 degrees C in liquid nitrogen tank and colony forming assays were examined to ascertain the colony forming ability of harvested bone marrow stem cells. Recovery of colony forming ability after cryopreservation in colony forming unit in culture and burst forming unit in erythrocyte is about 63 to 73% and well preserved. Among 6 cases undergone BMT, five cases are patients with advanced solid tumors including breast cancer, seminoma, lung cancer, malignant lymphoma and brain tumor and these 5 cases have undergone autologous BMT. Conditioning regimen for each cancer in autologous BMT differs based upon conventional chemotherapy regimen and two to four fold dose of conventionally used chemotherapy regimen were administered and after two or three days of high dose chemotherapy, cryopreserved bone marrow cells were thawed and infused. Peripheral white blood cells and platelets were recovered to more than 1000/microliters and 5 x 10(4)/microliters, respectively, within 21 days after bone marrow cell infusion. Disappearance or decrease in tumor size was observed in all cases except brain tumor even though those cases were advanced ones. After autologous BMT, recurrence occurred within three to five months in three cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Simple and effective method of electroporation for introduction of plasmid and cosmid DNAs to mammalian cells.

We have established a simple and efficient method of electroporation applicable to gene transfer in mammalian cells. It uses a single decaying pulse of around 1 ms at room temperature in the medium such as Saline G appropriate for repair of pulse-induced pores in the plasma membrane. Many types of cells (both floating and adherent) could be transformed efficiently by the electric field strengths between 1-2 kV/cm. For instance P3U1, mouse myeloma cell, could be transformed by a pulse at 1.2 kV/cm with the frequency of 10(-2) per viable cells and with survivals of 90%. We have applied these conditions to transform tsBN2 cell line of BHK21/13 by a cosmid clone (approximately 45 kb) carrying the human gene complementing to tsBN2 mutation. Significant levels of transformation were observed for this gene. Since this gene can only work as a whole size (approximately 30 kb), the results show that electroporation is useful to introduce cosmid or possibly genomic DNA to mammalian cells.

Animals↗
PubMed1988

[The significance of blood coagulation test in fulminant hepatic failure].

We treated 12 cases of fulminant hepatic failure with plasma exchange, cryofiltration and hemodialysis. Five cases were survived and 7 cases died. The liver volume measured by volus CT on admission was about 1106 ml in survived cases, and was about 457 ml in death cases. In cases which liver volume was under 600 ml, these prognoses were miserable. AT-III, PT and HPT activities were well correlated with liver volume (r = 0.85) and these activities were good indicator to treat the fulminant hepatic failure. The measurement of FBG and APTT were also useful for the estimation of the prognosis. But they were not becoming of indicator to treatment. We have no expectation to prognosis of the cases which PT, HPT and AT-III were under 15%, 10%, and 25%, respectively.

Adolescent↗
PubMed1988

[Paraurethral leiomyoma in a female: report of a case].

A 50-year-old female visited our clinic complaining of tumor formation in the external genitalia. The tumor was elastic hard upon palpation, 3 cm in diameter, and located in the right lateral side of the external urethral meatus. The paraurethral tumor was excised. Histopathological diagnosis was paraurethral leiomyoma. Female paraurethral leiomyoma is a rare benign tumor. There have been only 66 cases reported in the Japanese literature. We summarized these cases and studied their clinical features.

Female↗