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Biomedical subjects

K Yagi

Publications and source records attributed to K Yagi.

At least 577 records · Page 32Linked to original sources
PubMed1985

Assay of glucocerebrosidase using a fluorescent analogue of glucocerebroside for the diagnosis of Gaucher disease.

For the diagnosis of homozygotes and heterozygotes of Gaucher disease, glucocerebrosidase (glucocerebroside beta-D-glucoside glucohydrolase, EC 3.2.1.45) activity in lymphocytes was measured using a fluorescent analogue of glucocerebroside, 1-0-glucosyl-2-N-(dimethylaminonaphthalene-5-sulfonyl)-sphingosine as substrate. The activity in lymphocytes from homozygotes of Gaucher disease was found to be reduced markedly. This method is proved to be simple, sensitive, and specific as an assay of glucocerebrosidase activity for the diagnosis of Gaucher disease.

Clinical Enzyme Tests↗
PubMed1985

Reduction of various lipid hydroperoxides by rat liver homogenate.

Rates of disappearance of hydroperoxy groups of various lipid peroxides added to rat liver homogenate differed from each other. The hydroperoxy group of linoleic acid disappeared rapidly, while those of L-3-phosphatidyl choline dilinoleoyl and trilinolenin disappeared slowly. The hydroperoxy groups of cholesterol linoleate were stable in the homogenate. Most of the conjugated dienes of these lipid peroxides remained. The hydroperoxy groups of the unsaturated fatty acids of the phosphatidyl choline were found to be changed to hydroxy groups as analyzed by high-performance liquid chromatography.

Animals↗
PubMed1984

Use of a fluorescent analogue of galactocerebroside for assay of galactocerebroside beta-galactosidase activity in skin fibroblasts from patients with Krabbe's disease.

In order to diagnose Krabbe's disease (globoid cell leukodystrophy) or its carrier state in patients, galactocerebroside beta-galactosidase (galactosylceramidase) activity in cultured skin fibroblasts was measured with high-performance liquid chromatography using a fluorescent analogue of galactocerebroside, 1-O-galactosyl-2-N-(1-dimethylaminonaphthalene-5-sulfonyl)-sphingosine, as substrate. The enzyme activities in skin fibroblasts of the patients were found to be dramatically reduced when compared with those of controls. The assay can be adopted for diagnostic use in place of assays using radioisotope-labeled natural substrate.

Cells, Cultured↗
PubMed1984

Noxious inputs to supraoptic neurosecretory cells in the rat.

The effects of noxious stimuli were studied on discharge activity of the neurosecretory cells identified in the supraoptic nucleus by antidromic excitation after pituitary stimulation, in anaesthetized rats. Tail pinching excited 24% and inhibited spontaneous discharge of 6% of the 91 cells tested. Noxious heat stimuli (44-63 degrees C) applied to the hindlimb paw produced a transient excitation in 26% of the 23 cells tested. Electric stimulation of either the sciatic or cutaneous nerve with 20-Hz pulses for 1 s, at an intensity 5 times stronger than the threshold for evoking the changes in respiratory movements and blood pressure similar to those after tail pinching or noxious heat stimuli, excited about 30% of the cells tested. The excitation produced by these noxious stimuli preceded, on some occasions, the respiratory movement and blood pressure decrease which occurred concomitantly. Peristimulus time histograms of spontaneous discharges constructed during stimulation of either nerve at 1 Hz, revealed the presence of excitatory synaptic inputs in about 35% of the neurosecretory cells tested. These data indicate the existence of direct neural pathways which mediate excitatory synaptic inputs originating from nociceptors to supraoptic neurosecretory cells. Since 9 of the 22 cells which were excited by tail pinching exhibited a "phasic" pattern of spontaneous discharge which is known to characterize certain vasopressin-secreting neurones in rats, it is suggested that these excited cells were, at least in part, vasopressinergic.

Animals↗
PubMed1984

Conditioned heart rate response: testing under anaesthesia in rats.

Classically conditioned heart rate response was studied in anaesthetized rats. Rats were conditioned with photic stimuli followed by electric tail shocks in a conscious state and tested under anaesthesia for conditioned heart rate change. Testing photic stimuli evoked a transient bradycardia in about one-third of testing trials. Magnitude of the bradycardia was significantly greater in conditioned rats than that in untrained or control rats trained with electric tail shocks followed by photic stimuli. The difference was found to be mainly due to the difference in amplitude of individual bradycardia response rather than that in frequency of occurrence of the response. Testing stimuli also evoked a slight and sustained tachycardia, but magnitude of the tachycardia in conditioned rats did not differ significantly from that in control or untrained rats. These results suggest that effects of classical conditioning on autonomic functions can be detected and studied under anaesthesia.

Anesthesia↗
PubMed1984

Serum lipid peroxide levels of patients suffering from thermal injury.

Lipid peroxide levels and activities of various enzymes were examined in sera from five thermally injured patients. In all patients examined, serum lipid peroxide levels were increased in the early post-burn period, and thereafter activities of glutamate oxalacetate transaminase, glutamate pyruvate transaminase, alkaline phosphatase and lactate dehydrogenase in the sera became elevated in most patients. From these observations, it is considered that increased lipid peroxides in the bloodstream during the early post-burn period would cause damage to various organs, permitting the leakage of the enzymes into the blood. These results support the view that lipid peroxide may be regarded as a 'burn toxin'.

Adult↗
PubMed1984

Age-dependent changes in lipid peroxide levels in the lipoprotein fractions of human serum.

Lipid peroxide levels in serum lipoprotein fractions of young and old individuals, who had no significant disease, were studied. The lipid peroxide level, amount of lipids, and the ratio of the former to the latter were significantly elevated in the low density lipoprotein fraction of older adults. This indicates that the elevation of the serum lipid peroxide levels in older adults is mainly due to increased lipid peroxide level in the low density lipoprotein fraction.

Adult↗
PubMed1984

N-terminal region (domain 1) of calmodulin is the low affinity site for Ca2+. A 13C NMR study of S-cyanocalmodulin.

A single cysteine residue (Cys-27) of wheat calmodulin was labeled with 13C by cyanylation. No change in the Ca2+ saturation pattern was observed after the cyanylation. On titration which Ca2+, the chemical shift of the 13C-label showed a downfield shift. The downfield shift was observed at Ca2+/calmodulin molar ratios between 1.8 and 3.5, while a blue shift of the UV absorption of Tyr-139 was observed between 0 and 1.7. The result indicated the domain 1 containing Cys-27 to be the low affinity site for Ca2+.

Amino Acids↗
PubMed1984

Properties of myosin light chain kinase prepared from rabbit skeletal muscle by an improved method.

Myosin light chain kinase was prepared from rabbit skeletal muscle. DEAE-Sephadex, calmodulin-Sepharose 4B affinity gel and Ultrogel AcA 34 were used for the purification. It took 3 days for the preparation, and 6.2 mg of myosin light chain kinase was isolated from 600 g of frozen muscle. The molecular weight of the myosin light chain kinase estimated by sedimentation equilibrium analysis was 103,000 +/- 4,100. The isoelectric point was 5.0. Chemical modification of cysteine residues did not affect the catalytic activity, but modification of tyrosine residues diminished the activity. In order to activate myosin light chain kinase, it was necessary to bind calmodulin in an equimolar ratio and the dissociation constant was estimated to be 3.6 nM. The optimum pH for the catalytic activity was 7.5, and the activity was inhibited by NaCl and KCl. In the presence of 2.74 mg/ml myosin light chain and 75 mM KCl, the catalytic activity was found to be 88 s-1. The Vm and Km at 0.14 M KCl were 100 s-1 and 53 microM, respectively, for the isolated light chain as substrate and 70-80 s-1 and 19 microM for myosin as substrate.

Amino Acids↗
PubMed1984

Regulation of Mycobacterium smegmatis glutamine synthetase by adenylylation.

Glutamine synthetase from a Gram-positive acid-fast bacterium, Mycobacterium smegmatis, was purified to homogeneity from cells grown with glycerol-bouillon medium. Electron micrographs of the enzyme revealed a dodecameric arrangement of its subunits in two superimposed hexagonal rings, similar to the structure of glutamine synthetase of Escherichia coli. Disc electrophoresis in the presence of sodium dodecyl sulfate indicated a subunit molecular weight of 56,000. The sedimentation coefficient of the native enzyme was estimated to be 19.4S by ultracentrifugation in a sucrose gradient. Like the E. coli enzyme, the glutamine synthetase from M. smegmatis is regulated by adenylylation/deadenylylation. This conclusion was based on studies of the effect of snake venom phosphodiesterase treatment on the catalytic and spectral properties of the isolated enzyme. The AMP released from the enzyme by the phosphodiesterase was identified by thin-layer chromatography. Despite the structural similarity of both enzymes, striking differences were found between the catalytic properties of M. smegmatis and E. coli glutamine synthetases. The divalent cation specificity of the M. smegmatis enzyme was not altered by adenylylation of the enzyme, and deadenylylation of the enzyme caused a significant increase in the specific activities for both biosynthetic and transfer reactions with either Mg2+ or Mn2+.

Adenosine Monophosphate↗
PubMed1984

Localization and identification of covalently bound flavoproteins in rat liver mitochondria by prelabeling of their flavin moiety.

The covalently bound flavoproteins in rat liver mitochondria were prelabeled by injecting [14C]riboflavin into a rat, then liver mitochondria were obtained and further labeled with [3H]pargyline, a suicide inhibitor of monoamine oxidase. When the mitochondria were subjected to osmotic lysis, two covalently bound flavoproteins having molecular weights of 110,000 and 94,000 were found in the supernatant. These proteins were identified as sarcosine dehydrogenases. Upon treatment of the membranous fraction with 1% Triton X-100, succinate dehydrogenase with a molecular weight of 70,000 was found in the soluble fraction, while two well-separated proteins doubly-labeled with 14C and 3H were found in the insoluble fraction. Their molecular weights were 61,000 and 57,000. By isoelectric focusing, two 3H peaks were observed with pI values of 8.3 and 8.4. The former corresponded to the 61,000-dalton protein, and the latter, to the 57,000 one. From the data obtained by using selective inhibitors, deprenyl and clorgyline, the [3H]pargyline-binding proteins with molecular weights of 61,000 and 57,000 were assigned to proteins of monoamine oxidases of type A and type B, respectively.

Animals↗
PubMed1984

Calcium binding to tryptic fragments of calmodulin.

Fragments of scallop testis calmodulin were prepared by tryptic digestion. One peptide consisted of 75 amino acid residues from N-acetylalanine to lysine at position 75 (F12) and the other of 71 residues from aspartic acid at position 78 to C-terminal lysine (F34). Flow dialysis and equilibrium dialysis experiments revealed the existence of two Ca2+ binding sites in each fragment. Half-saturating concentrations of the Ca2+ titration curves were 11 microM for F12 and 3.2 microM for F34, and Hill coefficients were obtained as 1.14 and 1.84, respectively. The results indicate that the high-affinity sites for Ca2+ are located on the C-terminal region of the calmodulin. The sum of the two Ca2+ titration curves of F12 and F34 fits well to the curves of Ca2+ binding to intact calmodulin. This shows that the characteristic of Ca2+ bindings in intact calmodulin did not change after separation of the whole molecule into two domains, F12 and F34. The domains corresponding to F12 and F34 may exist independently from each other in the intact calmodulin molecule.

Animals↗
PubMed1984

[Aortocoronary bypass graft in coronary arterial stenosis with aortitis syndrome].

A 50-year old female who had aortitis syndrome with unstable angina due to severe coronary arterial narrowings is described. On the preoperative coronary arteriogram, 95% occlusion of the left anterior descending coronary artery (segment 6) and the left circumflex artery (segment 11), so-called "skip lesion" of aortitis syndrome, were revealed. The distal circumflex artery was well visualized through collateral vessels of the posterior descending branch of the right coronary artery. Therefore single aortocoronary bypass graft to the left anterior descending branch was done with good success. Postoperatively the patient has been completely free from anginal chest pain. Narrowing of the coronary artery due to aortitis syndrome is considered uncommon. Stenotic lesions have been reported to be limited mostly to the ostia and proximal segments of the coronary arteries, connecting to the aortic wall. Moreover, so-called "skip lesion" of the coronary artery as seen in this case is thought to be very rare.

Angina, Unstable↗