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Biomedical subjects

K Yagi

Publications and source records attributed to K Yagi.

At least 613 records · Page 34Linked to original sources
PubMed1983

Divalent cation binding to wheat germ calmodulin.

The Ca2+ binding to plant (wheat germ) calmodulin was measured in 0.1 M NaCl by a flow-dialysis method. The four macroscopic binding constants best fitted to the data were 0.20, 0.25, 0.025, and 0.0024 microM-1. The cysteine residue of this calmodulin is located at the 27th position from the NH2-terminal (Yazawa, M. et al. (1982) Abstr. 33th Conf. Protein Structure pp. 9-12, Osaka). According to the quantitative analysis of the reaction of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) with Cys 27, the calmodulin which binds 3 Ca2+ showed the minimum reactivity with DTNB. This suggests that the site for the third Ca2+ binding is located close to Cys 27. Cys 27 was spin-labeled with N-(2,2,6,6-tetramethyl-4-piperidine-1-oxyl)maleimide, and its ESR spectrum was measured in the presence of Mn2+ and/or Ca2+. The rotational relaxation time of the label (1.2 ns) was increased by about one-tenth with 1 to 2 mol of bound Ca2+, but was unchanged with Mn2+. On the other hand, Mn2+ induced a remarkable quenching of the spectrum. From the decrease in the peak heights of the ESR spectrum, the distance between the label and the first bound Mn2+ was estimated to be 0.8 nm. It is concluded that the first Mn2+ binds to a domain near the NH2-terminal. The difference UV absorption spectrum induced by Mn2+ was similar to that induced by Ca2+. However, the amount of Mn2+ needed to saturate the difference spectrum was 1 mol more than the amount of Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1983

Risks of occurrence of psychoses in relation to the types of epilepsies and epileptic seizures.

The possible existence of the risks of occurrence of psychoses was examined in relation to the types of epilepsies and epileptic seizures. This study consisted of two investigations: 1) A study of 879 epileptic patients was conducted in which the incidence of psychoses in the different types of epilepsies was surveyed; the result was that the incidence in temporal lobe epilepsy was the highest, being relatively higher than that of other (non-temporal lobe) partial epilepsies but not significantly different from that of generalized epilepsies. 2) A comparative study was carried out on 96 patients with temporal lobe epilepsy in which 48 were psychotic and another 48 were non-psychotic which served as a control group. The differences of seizure symptomatology between the two groups were compared. The results were that the psychotic group was found to exhibit at a significantly higher rate generalized tonic-clonic convulsion and compound seizure manifestations in comparison with the non-psychotic group. The results appear to support the fact that generalizing mechanisms of temporal lobe epileptic manifestations are closely related to a physiopathogenic factor influencing psychoses.

Adolescent↗
PubMed1983

Occurrence of riboflavinyl glucoside in rat urine.

To investigate the metabolism of riboflavin, [2-14 C]-riboflavin was administered orally to a rat. The urine pooled for 24h after administration was fractionated by paper and silica gel thin layer chromatographies using various solvent systems. Among the radioactive metabolites, riboflavinyl glucoside was found along with 7-carboxy lumichrome and 8-carboxy lumichrome. The radioactivity of riboflavinyl glucoside comprised about 6% of the total radioactivity excreted in the urine during 24h.

Animals↗
PubMed1983

Kinetics of primary interaction of D-amino acid oxidase with its substrate.

The formation of an initial enzyme-substrate complex of D-amino acid oxidase (D-amino acid: O2 oxidoreductase (deaminating), EC 1.4.3.3) and its substrate, D-alpha-aminobutyric acid, was studied kinetically at lower temperature and pH than their optima. The time course of the absorbance change at 516 nm in an anaerobic reaction was not exponential, but biphasic. The ratio of the rapidly reacting component to the slowly reacting one was decreased upon lowering of the temperature. The reaction rate of the rapidly reacting component depended on substrate concentration and gave a linear Arrhenius plot in the temperature range from -10 to +15 degrees C. The reaction rate of the slowly reacting component also depended on both substrate concentration and temperature. The rapidly reacting and slowly reacting components could be assigned to the substrate binding of the dimer and monomer, respectively, of this enzyme.

Aminobutyrates↗
PubMed1983

New metabolites of riboflavin appeared in rat urine.

By using paper and silica gel thin layer chromatography with various solvent systems, flavin compounds appeared in rat urine after administration of radioactive riboflavin were analyzed in detail. Two new metabolites having radioactivity were separated and their structures were determined to be 7-carboxy lumichrome and 8-carboxy lumichrome. The sum of radioactivities of these two compounds was about 46% of total radioactivity excreted in the urine during 24 h.

Animals↗
PubMed1982

Degeneration of retinal neuroblasts by chinoform-ferric chelate.

The possible mechanism of neuropathic effect of chinoform was investigated using cultured retinal neuroblasts from chick embryos. Retinal neuroblasts completely degenerated by chinoform-ferric chelate within a day. This change, however,, was not observed with free chinoform or ferric ion alpha-Tocopherol had a potent protective effect on the toxicity of the chelate. From these results, it was concluded that the lipid peroxidation due to ferric ion chelated with chinoform incorporated into the membrane of nerve tissues is the most important step in induction of the neuropathy.

Animals↗
PubMed1982

Amygdalar inputs to ADH-secreting supraoptic neurones in rats.

Effects of amygdala stimulation on the discharge activity of antidromically identified supra-optic neurosecretory neurones were studied in male rats anaesthetized with urethane. Stimulation of the medial and the basal amygdala produced excitation or inhibition of discharge activity both in phasically firing ("phasic") and in continuously firing ("continuous") neurones. More "phasic" neurones were excited than were inhibited after medial amygdala stimulation. On the other hand, fewer "continuous" neurones were excited by stimulation of the either amygdala area than were inhibited. This difference of responsiveness between "phasic" and "continuous" neurones is statistically significant. Synaptic inputs to supraoptic neurosecretory neurones after amygdala stimulation were also observed in rats with a lesion of the stria terminalis. Supraoptic nucleus stimulation activated antidromically 14 of the 336 amygdala neurones tested. Since "phasic" neurones have been identified as ADH-secreting neurones, it is concluded that ADH-secreting neurones in the rat supraoptic nucleus receive predominantly excitatory synaptic inputs from the medial amygdala and these amygdalar synaptic inputs are mediated by pathways which are at least in part monosynaptic and are not included in the stria terminalis.

Amygdala↗
PubMed1982

Cerebellar infarction with obstructive hydrocephalus.

The authors review 15 patients with acute cerebellar infarction accompanied by obstructive hydrocephalus. These patients were among 1700 consecutive patients with acute cerebrovascular disease who were examined by angiography and also, except for the initial 320 cases. by computerized tomography (CT) scan. The CT scans were helpful in diagnosis and management of the patients. It demonstrated cerebellar mass lesions as being low density, isodense, or high density, according to the amount of hemorrhage into the infarcted area. Such cerebellar mass lesions caused acute compression of the posterior fossa. The clinical picture was determined mainly by the extent of the initially infarcted area in the vertebrobasilar territory and the speed of enlargement of the subsequently developing cerebellar mass lesion. Suboccipital decompressive surgery was performed in 10 patients and was generally beneficial. The postoperative prognosis depended mainly on the presence or absence of coexisting brain-stem infarction. Five patients who were managed conservatively died during the acute stage. Prompt and correct diagnosis of this illness is required to ensure adequate therapy.

Adult↗