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Biomedical subjects

Y Asano

Publications and source records attributed to Y Asano.

At least 703 records · Page 39Linked to original sources
PubMed1985

Lyb-5+ B cells can be activated by major histocompatibility complex-restricted as well as unrestricted activation pathways.

It has previously been demonstrated that B cells can be activated through two distinct T helper (Th) cell-dependent pathways, one requiring both carrier-hapten linkage and MHC-restricted T-B interaction and the other requiring neither. In addition, it has been shown that different B cell subpopulations exist and that these subpopulations differ in their activation requirements. Previous studies demonstrated that resting B cells containing an Lyb-5+ subpopulation were activated by MHC-unrestricted T cell signals, whereas resting Lyb-5- B cells were activated only through MHC-restricted T-B interaction. It was suggested that this difference resulted from the ability of Lyb-5+ but not Lyb-5-B cells to respond to soluble MHC-unrestricted Th signals. Because Lyb-5+ B cells were responsive in these previous experiments to MHC-unrestricted Th signals, it could not be determined whether Lyb-5+ B cells were also responsive to MHC-restricted Th signals. Consequently, the present study was undertaken to directly address the question of whether Lyb-5+ B cells can be activated under appropriate conditions by MHC-restricted as well as unrestricted T cell-B cell interactions. It was found that unprimed normal B cells (containing Lyb-5+ and Lyb-5-B cells) but not unprimed xid-defective populations (Lyb-5- only) can be activated by cloned KLH-specific and MHC-restricted Th cells in response to either high or low concentrations of TNP-KLH. The IgM response of Lyb-5+-containing B cells to a high concentration of antigen (10 micrograms/ml) was MHC unrestricted, whereas the IgM response of unprimed Lyb-5+ B cells to a low concentration of antigen (0.001 micrograms/ml) was MHC restricted. Thus, unprimed Lyb-5+ B cells can be activated through both MHC-restricted and unrestricted pathways. It was further demonstrated that the activation requirements of Lyb-5+ and Lyb-5- B cells differed even for MHC-restricted B cell activation.

Animals↗
PubMed1984

Stereochemical course of the transmethylation catalyzed by histamine N-methyltransferase.

The stereochemical course of the methyl group transfer catalyzed by histamine N-methyltransferase was studied using S-adenosylmethionine (AdoMet), which carried a chiral methyl group. The incubation of these AdoMet samples and histamine with a partially purified enzyme obtained from guinea pig brains gave the corresponding methylated histamine. The N-methylhistamine samples were degraded to convert the N-methyl group into the methyl group of acetate using a reaction sequence of known stereochemistry. The results of the configurational analysis of these acetate samples indicated that the enzymatic transfer of the methyl group from the sulfur of AdoMet to the nitrogen of histamine occurs with inversion of configuration.

Animals↗
PubMed1984

Decreased sodium influx and abnormal red cell membrane lipids in a patient with familial plasma lecithin: cholesterol acyltransferase deficiency.

Red cell membrane metabolism in familial lecithin:cholesterol acyltransferase (LCAT) deficiency was investigated. The family presented here is the third case discovered in Japan. An increase of free cholesterol was observed in the red cell membranes, concomitant with increased phosphatidyl choline. Osmotic fragility of the patient's red cells was diminished rather than increased. Red cell survival (51Cr T1/2) was shortened (15 days). Sodium influx was markedly decreased, although sodium efflux, both ouabain-sensitive and ouabain-insensitive, was normal. The activity of acetyl-cholinesterase as a marker of the outer leaflet of the red cell membranes was decreased, while the activity of glyceraldehyde-3-phosphate dehydrogenase as a marker of the inner leaflet was normal. No abnormalities of adenosine triphosphatases in red cell membranes were observed. These results suggest that the alteration of cholesterol metabolism in the plasma of LCAT deficiency increases the red cell membrane cholesterol and affects the functions of the red cell membranes, especially of the outer leaflet, which may result in decreased sodium influx.

Blood Transfusion↗
PubMed1984

Immunogenicity of wild and attenuated varicella-zoster virus strains in rhesus monkeys.

Thirty susceptible rhesus monkeys were inoculated with cell-free varicella-zoster virus strain OKA or strain KMcC. Both wild and attenuated strains were used. No clinical signs characteristic of human varicella were seen in any of the animals. Virus was not isolated from throat swabs, blood, or cerebrospinal fluid. Antibodies were measured by an enhanced plaque neutralization test. The wild and attenuated OKA strains produced comparable levels of antibodies for 3 months after inoculation. Attenuated KMcC strains produced lower titers than the wild strain. On rechallenge 3 months after primary inoculation animals boostered with the attenuated OKA strain developed significantly higher antibody titers than animals receiving the wild strain. Animals primed and challenged with the attenuated KMcC strains showed significantly lower antibody titers than animals which received the wild strain. The results indicate that the immunogenicity of attenuated OKA and KMcC strains in rhesus monkeys parallels the experience obtained with these strains in humans.

Animals↗
PubMed1984

Effects of plasma infusion on plasma lipids, apoproteins and plasma enzyme activities in familial lecithin: cholesterol acyltransferase deficiency.

The siblings presented here are the third family found in Japan with familial LCAT deficiency. Their post-heparin plasma lipoprotein lipase and hepatic triglyceride lipase activities were measured selectively by an immunochemical method. Plasma triglyceride levels were elevated, and post-heparin plasma lipoprotein lipase was decreased only in a patient with nephropathy, while hepatic triglyceride lipase activities were within reference limits in both patients. The plasma concentrations of apo A-I, apo A-II, and apo B were reduced in both patients. On the other hand, the plasma concentration of apo E was markedly increased. Enzyme replacement therapy by plasma transfusion in the propositus resulted in marked improvement of deranged compositions of triglyceride-rich lipoproteins. Also, improvement of the plasma apo E concentration was demonstrated, while the improvement of post-heparin lipase did not occur. These results suggest that LCAT may play an important physiological role in triglyceride metabolism as well as in cholesterol metabolism.

Apoproteins↗
PubMed1984

Lens subluxation in homocystinuria. A case report.

A 6-year-old girl had bilaterally subluxated lenses and liver and platelet dysfunctions. A cyanide-nitroprusside test of the urine was positive. Serum and urinary levels of methionine and homocystine were high. Cystathionine synthetase activity in the cultured skin fibroblasts was negligible. Pyridoxine, 1000 mg/day orally, normalized the serum and urinary methionine and homocystine levels and the liver and platelet functions. Episodes of pupillary block glaucoma prompted lens extraction. The subluxated lenses were extracted under general anaesthesia after administration of pyridoxine and dextran to avoid thrombosis. A good result without serious complications was obtained. We believe that homocystinuria should not be considered a contra-indication to general anaesthesia. In the pyridoxine-responsive patient general anaesthesia is not hazardous if platelet function can be controlled by the vitamin.

Anesthesia, General↗
PubMed1984

Distribution of alpha-adrenergic receptors in the rabbit nephron.

In order to determine the distribution of alpha-adrenergic receptors within a nephron, a method was used to determine the specific binding of [3H]-prazosin to isolated fragments of rabbit renal tubules. When 10(-8) moles/liter [3H]-prazosin was incubated with proximal convoluted tubules, 61.4% of total binding was accounted for specific binding. The [3H]-prazosin binding to the proximal convoluted tubule was a linear function of the tubular length and reversible. It was inhibited with 10(-4) moles/liter phenoxybenzamine by about 60%, and with 10(-4) moles/liter norepinephrine by about 25%, but not with either atenolol or isoproterenol. No specific binding of [3H]-prazosin was observed in the proximal straight tubule and in the cortical collecting tubule. These data are in good agreement with the view that alpha-1 adrenergic receptors are mainly distributed in the proximal convoluted tubules.

Animals↗
PubMed1984

Increase of beta-endorphin levels in cerebrospinal fluid but not in plasma in patients with cerebral infarction.

beta-Endorphin was measured in cerebrospinal fluid (CSF) and plasma in patients with cerebral infarction at acute (4 to 48 hours) and chronic (1 month) stages. Only CSF samples obtained in the acute stage showed beta-endorphin values that were statistically higher than those measured in a control population. This finding suggests that infarction at its acute stage gives rise to an increased release of beta-endorphin. Such a mechanism is consistent with the possibility that the reported therapeutic effect of naloxone in cerebral ischemic lesions may result in part from the antagonism of the centrally released endorphin, beta-endorphin.

Adult↗
PubMed1984

Clinical trial of the Oka strain of live attenuated varicella vaccine on healthy children.

Clinical and serological follow-up studies were made on 257 healthy children who had received live varicella vaccine (strain Oka) in Showa Hospital. Good antibody responses were shown with a seroconversion rate of 98.4% (253/257) by the immune adherence hemagglutination test. Mild adverse reactions were observed in 11 of the vaccinated children. During observation periods of 6 months to 4 years, 6 of the 253 children who were successfully vaccinated contracted mild varicella, while all 4 vaccinees who showed no primary immune response contracted mild to moderate clinical varicella. It is concluded that this vaccine is highly immunogenic and causes few clinical reactions in normal children.

Adolescent↗
PubMed1984

T cell regulation of B cell activation: MHC-restricted T augmenting cells enhance the B cell responses mediated by MHC-restricted cloned T helper cells.

The present studies demonstrated that unprimed populations of Lyt-1+2- T cells are able to augment the responses generated by optimal numbers of antigen-specific and MHC-restricted cloned TH cells. The TA cells function early in the course of B cell responses. Responses mediated by (A X B)F1 (B + accessory) cells and parentA restricted cloned TH cells are augmented by TA cells from (A X B)F1 leads to parentA radiation bone marrow chimeras, but not by TA cells from (A X B)F1 leads to parentB chimeras. Thus, TA cell activation and function are MHC-restricted, but this restriction is not related to recognition of genotypically expressed B cell and/or accessory cell MHC products alone. Rather, TA cell function is intimately related to the MHC-restricted interaction between TH cells and responding (B + accessory) cells. Specifically, it was shown that TH cell interaction with B cells via an MHC-restricted and carrier-hapten-linked pathway is required for the function of TA cells expressing the same MHC restriction. Moreover, neither MHC homology nor TH cell recognition of MHC determinants on TA cells is required for TA cell function, and the activity of TA cells is not demonstrably influenced by non-MHC genes. It was further demonstrated that the function of cloned TH cells in B cell activation consists of at least two distinct components, one is radiosensitive and the other is radioresistant. TA cells are able either to replace the radiosensitive function of cloned TH cells directly or to bypass this requirement through an alternative pathway.

Animals↗
PubMed1984

T cell regulation of B cell activation. An antigen-mediated tripartite interaction of Ts cells, Th cells, and B cells is required for suppression.

To determine the requirements underlying the antigen specificity observed in T cell-mediated immune response suppression, cloned major histocompatibility complex (MHC)-restricted T suppressor (Ts) cells specific for keyhole limpet hemocyanin (KLH) and cloned MHC-restricted T helper (Th) cells specific for fowl gamma-globulin (FGG) were employed to study the regulation of trinitrophenyl (TNP)-specific B cell responses. Neither antigen bridging between Ts cells and Th cells (FGG=KLH) nor bridging between Ts cells and B cells (TNP-KLH) was sufficient to allow suppression; a mixture of FGG=KLH and TNP-KLH was also insufficient for suppression. In contrast, suppression was induced by KLH-specific Ts cells only when suppressor determinants (KLH), helper determinants (FGG), and B cell determinants (TNP) were covalently linked on the same molecule (TMP-FGG)=(TNP-KLH) or TNP-(FGG=KLH)). These findings imply that a tripartite antigen-mediated interaction of Ts cells, Th cells, and responding B cells is necessary for the mediation of this antigen-specific suppression.

Animals↗
PubMed1984

Effects of parathyroid hormone and calcitonin on stop-flow patterns of cyclic AMP, sodium, potassium, calcium and inorganic phosphate in thyroparathyroidectomized rabbits.

Conventional stop-flow studies were performed in thyroparathyroidectomized rabbits in order to examine the effects of parathyroid hormone (PTH) and calcitonin on urinary excretion of 3',5'-cyclic adenosine monophosphate (cAMP), Na, K, Ca, and inorganic phosphate (Pi). PTH markedly increased excretion of cAMP in the distal as well as in the proximal fractions. PTH increased Na concentration at the proximal and the distal fractions. K concentration was increased with PTH in all segments, and two prominent peaks were observed at the late proximal and the terminal fractions. Although changes in the pattern of Ca concentration after PTH were similar to those of Na, the pattern of Ca concentration normalized by Na concentration (Ca/Na) showed a decrease in Ca concentration in the late distal fractions. PTH increased Pi concentration in two portions, the proximal and the late distal fractions. Calcitonin slightly increased excretion of cAMP at the midfractions. Calcitonin did not cause any significant changes in the patterns of Na and Pi, but increased Ca concentration in the early distal fractions and K concentration in the late proximal fractions. From these findings we suggest: (a) nephrogenous cAMP responsive to each hormone partly corresponds to nephron distribution of hormone-dependent adenylate cyclase; (b) the sites of action of these hormones are quite distinct in the rabbit kidney; (c) the distal nephron segments play important roles in anticalciuric and phosphaturic actions of PTH, and (d) mechanisms of increases in K excretion by these two hormones may be different.

Adenylyl Cyclases↗