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Biomedical subjects

K Yagi

Publications and source records attributed to K Yagi.

At least 415 records · Page 23Linked to original sources
PubMed1991

Micro-determination of L-gulono-gamma-lactone oxidase activity.

Highly sensitive assay method of L-gulono-gamma-lactone oxidase (GLO) was constructed. In this method, L-ascorbic acid formed in the enzymatic reaction was converted to its bis(dinitrophenyl)hydrazone derivative, and the amount of the latter was determined by high-performance liquid chromatography. Twenty picomoles of ascorbic acid was detected, which makes this method 25 times more sensitive than the previously used dipyridyl one. By the present method, a minute activity of GLO in liver microsomes prepared from rats of the Osteogenic Disorder Shionogi strain (ODS-od/od) could be measured.

Animals↗
PubMed1991

Effect of linoleic acid hydroperoxide on production of matrix metalloproteinases by human skin fibroblasts.

The effect of linoleic acid hydroperoxide on in vitro production of matrix metalloproteinases (MMPs) by human skin fibroblasts was studied. The addition of linoleic acid hydroperoxide significantly increased the production of MMP-1 (tissue collagenase) and MMP-3 (stromelysin), while it rather decreased that of MMP-2 (gelatinase of 72 kDa; so-called "type IV collagenase"). The effect of lipid peroxides to alter collagen metabolism was discussed from pathogenic points of view.

Cells, Cultured↗
PubMed1991

1H NMR study on amide proton exchange of calmodulin-mastoparan complex.

Amide proton exchange rates of Ca2(+)-saturated calmodulin and Ca2(+)-saturated calmodulin-mastoparan complex were studied by 1H NMR spectroscopy. Exchange rates of Gly25, Gly61, Gly98, Gly134, Ile27, Ile100, and Asn137 were determined for Ca2(+)-saturated calmodulin and for Ca2(+)-saturated calmodulin-mastoparan complex, and were found to be less than 10(-4)s-1. All these residues of which the amide proton resonances appear at lower fields were considered to form hydrogen bonds, based on the results of X-ray analysis. Exchange rates of Ile27 and Asn137 became an order of magnitude smaller when mastoparan bound to Ca2(+)-saturated calmodulin, while those of the four glycines and Ile100 did not change appreciably. The reduction in accessibility of Asn137 to water cased by mastoparan binding suggests that a part of the mastoparan binding site is probably located in or near the hydrophobic cluster of the C-terminal-half domain. The reduction in accessibility of Ile27 also suggests that another part of the mastoparan binding site is located in or near the hydrophobic cleft of the N-terminal-half domain.

Amino Acids↗
PubMed1991

[Auditory brain stem response in patients with consciousness disturbance].

To investigate the prognosis for patients with consciousness disturbance, we recorded auditory brain stem response (ABR) in 35 patients with primary or secondary brain damage. For patients with secondary brain damage, the first ABR recorded after admission could be used not only to differentiate consciousness level but also to predict prognosis. However, for the patients with primary brain damage, the first ABR could not be used for either differentiating consciousness level or predicting prognosis. In addition, in two patients with secondary brain damage, the series of ABR recordings indicated that brain stem damage was reversible.

Adolescent↗
PubMed1991

[Three cases of subacute panencephalitis showing asterexis-like movements].

We reported 3 cases with subacute sclerosing panencephalitis (SSPE) showing recurrent and involuntary motor phenomena. Their electroclinical correlates were analyzed using CCTV-EEG. Clinically, they slanted their trunks and/or heads, and dropped their upper limbs momentarily only when their antigravity muscles were suitably contracting (sitting, standing, or stretching out their arms). Electrographically, the motor phenomena corresponded with the occurrence of periodic synchronous discharges (PSD) (in one-to-one manner). EMG potentials associated with the muscle contraction subsided at the very moment. These motor phenomena observed in patients with SSPE were discussed in relation to asterexis.

Adolescent↗
PubMed1990

Growth inhibition of glioma cells transfected with the human beta-interferon gene by liposomes coupled with a monoclonal antibody.

A human beta-interferon (HuIFN-beta) gene inserted into a eukaryotic expression vector (pSV2IFN-beta) was entrapped in liposomes having positive charges on their surface. Liposome-mediated transfection of the gene into cultured glioma cells (U251-MG) resulted in the secretion of HuIFN-beta into the medium. The HuIFN-beta level in the culture medium of glioma cells reached 24 +/- 8 (mean +/- SD) IU/ml after 96 h of incubation, at which level the growth inhibitory effect on the cells was found to be greater than 40 times as compared with exogenously added HuIFN-beta. When the plasmid-containing liposomes were coupled with a monoclonal antibody (G-22 MCA) against glioma-associated antigen, the level of HuIFN-beta in the medium was 178 +/- 26 IU/ml, resulting in a 7-fold increase, and the growth inhibitory effect was further elevated. Since the addition of a monoclonal antibody against HuIFN-beta to the medium did not cause the cell growth to resume, the growth inhibitory effect on the cells seems to be ascribed to HuIFN-beta produced in the cells transfected with its gene. Accordingly, the specific delivery of the HuIFN-beta gene into glioma cells by the use of such liposomes might become a useful technique for gene therapy of malignant glioma.

Animals↗
PubMed1990

Interactions between emotional stress due to fear and hypovolemic stimuli in the control of vasopressin secretion in rats.

Interactions between emotional stress due to fear and hypovolemic stimuli on vasopressin secretion were studied in rats. Intraperitoneally injected dextran did not significantly change plasma osmolality and arterial blood pressure but increased blood hemoglobin and plasma vasopressin level. An i.v. infused physiological solution reversed these changes. Emotional stress due to fear acquired by learning suppressed plasma vasopressin level in dextran-injected rats. Emotional stress due to fear produced by low-frequency footshocks also suppressed the increased plasma vasopressin level. These results suggest that emotional stress due to fear interacts with afferent neural signals originating from cardio-vascular volume receptors in the control of vasopressin secretion.

Animals↗
PubMed1990

1H NMR study of rabbit skeletal muscle troponin C: Mg2(+)-induced conformational change.

Binding of Mg2+ to rabbit skeletal muscle troponin C (TnC) is studied by means of two-dimensional (2D) 1H NMR spectroscopy. Using the sequence-specific resonance assignment method we assign several resonances of TnC in the Mg2(+)-saturated state. Assigned resonances are used as probes of the following titration experiments: (1) Mg2+ titration of apo-TnC, (2) Mg2+ titration of Ca2TnC, and (3) Mg2+ titration of Ca4TnC. In experiment 1, the slow-exchange behavior is observed for resonances of Phe99, Asp107, Gly108, Tyr109, Ile110, Asp111, His125, Gly144, Arg145, Ile146, Asp147, and Phe148 located at the high-affinity Ca2(+)-binding sites in the C-terminal-half domain. In experiments 1 and 2, the fast-exchange behavior is observed for resonances of Gly32, Asp33, Ser35, Gly68, Thr69, and Asp71 located at the low-affinity Ca2(+)-binding sites in the N-terminal-half domain. These results suggest that Mg2+ ions bind to the N domain as well as the C domain. In experiment 3, no spectral change is observed for all above-mentioned residues in the C domain and also for Gly32 and Gly68 in the N domain. It can be concluded that all Ca2(+)-binding sites in both the N and C domains can bind Mg2+ ions. No significant change is observed for resonances of Phe23, Ile34, Val68, and Phe72 in experiments 1 and 2. These results suggest that Mg2+ binding to the N domain does not induce conformational change in the hydrophobic region of the N domain. 2D-NMR spectra and Mg2(+)-titration data suggest that the antiparallel beta-sheet conformation is formed in both the N and C domains when Mg2+ ions bind to the two domains.

Animals↗
PubMed1990

Differential effects of naloxone on neuroendocrine responses to fear-related emotional stress.

The effects of an opioid receptor antagonist, naloxone (NAL), were studied on the changes in pituitary hormone secretion induced by emotional stress. Male Wistar rats were trained with tone stimuli paired with electric footshocks and tested with the tone and environmental cue signals for emotional stress of fear acquired by learning as described previously (Onaka et al. 1988). Rats received s.c. injected NAL 30 min before testing at doses of 0, 0.2, 1.0, 5.0 and 25.0 mg/kg b.w. Half the rats were injected with 0.5 M NaCl (20 ml/kg b.w.) together with NAL. In these hypertonic rats plasma vasopressin level was slightly increased after NAL. The increment was statistically significant in control groups but not in experimental groups. However the suppression of vasopressin secretion by emotional stimuli was not changed by NAL. Plasma oxytocin levels were extremely high and not significantly different among experimental, unshocked control and untested control groups. NAL further increased the oxytocin level dose-dependently. NAL did not significantly change plasma adrenocorticotrophic hormone (ACTH) levels and hence did not modify the augmentative response in ACTH secretion to emotional stimuli. Plasma prolactin level was significantly elevated after emotional stimuli and NAL depressed the prolactin level in each of experimental and control groups. After NAL, the magnitude of the facilitatory response in prolactin secretion to emotional stimuli was decreased. Motor activity and its suppressive response to emotional stimuli were not influenced by NAL. In another half of rats under a normal osmotic condition the vasopressin response to emotional stimuli was not affected by NAL. NAL further augmented potentiation of oxytocin secretion after emotional stimuli dose-dependently.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1990

Inter-domain interaction and the structural flexibility of calmodulin in the connecting region of the terminal two domains.

The calcium-dependent difference absorption spectrum of scallop calmodulin was measured in the presence of mastoparan. The difference spectrum at 286 nm (delta A286) showed biphasic response to Ca2+ concentration. The first change represents the conformational change around Tyr-138 and the second change may respond to an interaction between N- and C-domain of calmodulin which became apparent in the associated state with mastoparan. Calmodulin-mastoparan complex was eluted from a gel filtration column after free calmodulin in the presence of Ca2+, which indicates a more compact structure of calmodulin-mastoparan complex than of free calmodulin. The biphasic response of delta A286 was also observed with free calmodulin when the ionic strength was as low as 0.02 M NaCl. In the absence of NaCl, the Ca2+ dependence of delta A288 was monophasic, assuming identical affinity of Ca2+ to both domains. Increase in the sensitivity of calmodulin to trypsin was observed with decrease in ionic strength. These results suggest an ionic-strength-dependent decrease in ordered structure of the connecting region. Calmodulin may change shape depending upon the ionic strength by bending at the connecting region. We assumed from the observations that calmodulin in solution may fluctuate between the two extreme shapes of the bent and the dumbbell structure. Target proteins may select and fix the specific bent structure for their activation.

Animals↗
PubMed1990

Histone H1 kinase specific to the SPKK motif.

A protein kinase phosphorylating sea urchin spermatogenous histones, H1 and H2B, was found in sea urchin egg homogenate and purified. The kinase is activated by cAMP and is composed of two different types of subunits with molecular masses 41 and 46 kDa. The kinase phosphorylates a peptide, Ser-Pro-Arg-Lys-Ser-Pro-Arg-Lys, which is a double repeat of the DNA-binding SPKK motif [Suzuki M., (1989) EMBO J. 8, 797-804]. We name this kinase SPkinase because it exclusively phosphorylates H1 and H2B, the only histones containing SPKK motifs. Phosphorylation of H1 by SPkinase decreases the DNA-binding ability of H1. This paper is the first to report purification of a kinase which affects the DNA-binding ability of a gene regulatory protein.

Amino Acid Sequence↗
PubMed1990

Measurement of blood cyanide with a microdiffusion method and an ion-specific electrode.

The use of a cyanide ion-specific electrode in combination with the Conway microdiffusion method was modified for the measurement of cyanide concentration in human red blood cells and plasma. With our modified method, the optimal pH of cyanide isolation from red blood cells and plasma was investigated. Cyanide recovery from red blood cells increased with decreasing pH. The maximal recovery of 96.9 +/- 2.6% was obtained at a pH of less than 1. Cyanide recovery from plasma, however, peaked at a pH between 7 and 8, and further changes in pH reduced the recovery rate. The maximal recovery rate from plasma was 74.1 +/- 1.5%. In previous studies, cyanide isolations from both plasma and red blood cells were carried out at a pH of less than 1. This study shows that cyanide isolation from plasma should be performed at a pH between 7 and 8.

Blood Chemical Analysis↗
PubMed1990

Surgical treatment of epilepsy in the comprehensive care program: advantages and considerations.

To properly establish the surgical treatment of epilepsy in the comprehensive care program, we planned a surgical strategy mainly for a temporal lobe epilepsy and have performed 60 temporal lobectomies. The surgical candidates were selected from 142 patients who met the initial criteria, and passed the initial evaluation for surgical intervention. Forty-five patients had long-term intracranial EEG recording, and circumscribed organic lesions were disclosed in 27 patients by neuroimaging techniques. The outcome of 23 patients who were followed for 2 years postoperatively was complete freedom from complex partial seizures in 17 patients (74%) and an increase in full employment from 2 to 10 patients. Despite the possible surgical complications, including detrimental effects on the higher cerebral functions, it is essential that the surgical treatment of epilepsy should be established as a part of the comprehensive care program. Our experiences and analyses of the state of the art in surgical intervention also suggest that surgical indications for more intractable patients whose social adjustment is less hopeful should be established and the surgical care system for these patients should also be planned. Furthermore, some patients may be free from recurrent seizures postoperatively, but still have difficulties in social rehabilitation. The problems for such patients remain unsolved.

Adult↗
PubMed1990

Subtypes of temporal lobe epilepsies: a clinical point of view.

We studied 40 patients with temporal lobe epilepsies who had long-term intracranial EEG recordings and temporal lobectomies. They were divided into 3 groups on the basis of the anatomical site of seizure origin. An electrode implantation technique combined intracerebral depth electrodes with subdural strip electrodes. The seizures were of amygdalo-hippocampal origin in 18 patients, lateral temporal in 13 patients, and temporo-basal in 9 patients. The clinical and EEG features were reviewed retrospectively with regard to 3 factors in each patient: localization of interictal spikes in the scalp-recorded EEG, signal symptoms (auras), and presumed etiologies. Epilepsy with amygdalo-hippocampal and lateral temporal seizures was found to be distinguishable by the electroclinical features. It seems practical to classify these 2 subtypes of temporal lobe epilepsies as in the 1989 Classification of Epilepsies and Epileptic Syndromes. Temporal lobe epilepsies thus defined can be regarded as epileptic syndromes rather than a cluster of seizure manifestations.

Adolescent↗