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Biomedical subjects

Y Tsuda

Publications and source records attributed to Y Tsuda.

At least 199 records · Page 11Linked to original sources
PubMed1989

Synthesis of peptide fragments related to eglin c and examination of their inhibitory effect on human leukocyte elastase, cathepsin G and alpha-chymotrypsin.

Various kinds of peptide fragments related to eglin c were prepared by the conventional solution method and their inhibitory effects on human leukocyte elastase, cathepsin G and alpha-chymotrypsin were examined. Peptide (31-40) inhibited cathepsin G (Ki = 2.3 x 10(-4) M), peptide (41-49) potently inhibited cathepsin G and alpha-chymotrypsin (Ki = 4.2 x 10(-5) M and 2.0 x 10(-5) M, respectively), and peptide (60-63) inhibited leukocyte elastase (Ki = 1.6 x 10(-4) M), whereas, peptide (31-35) weakly inhibited both elastase and cathepsin G (Ki = 2.1 x 10(-3) M and 7.3 x 10(-4) M, respectively).

Amino Acid Sequence↗
PubMed1989

Quantitative correlation between cardiovascular and plasma epinephrine response to mental stress.

To investigate the quantitative correlations between cardiovascular and endogenous catecholamine response to mental stress, we gave a mental arithmetic test to 20 young healthy men. A direct and non-invasive haemodynamic measurement was performed by serial M-mode echocardiography. Heart rate, blood pressure, cardiac output, stroke volume, ejection fraction, left ventricular end-systolic pressure-volume ratio and plasma epinephrine increased over the baseline period during the test. The peripheral resistance and left ventricular end-systolic volume decreased, whereas left ventricular end-diastolic volume and plasma norepinephrine were unaltered. Furthermore, the degree of change in each haemodynamic parameter showing significant reaction, was well correlated with that of the increase in plasma epinephrine. The data suggest that acute mental stress induces endogenous epinephrine secretion resulting in a beta-adrenergic activated state in the cardiovascular system, namely, positive chronotropism, positive inotropism and vasodilatation.

Adult↗
PubMed1989

Study of the excretion mechanism of a perfluorochemical emulsion.

The excretion mechanism of perfluorochemicals (PFC) via the lung has been studied by physicochemical and histochemical methods. Monocytes that had phagocytized PFC particles were found in the lung capillaries, and alveolar macrophages that had phagocytized PFC particles were found in the alveoli. Vacuolated macrophages were observed microscopically in the alveolar space of rats injected with PFC emulsions. The PFC content in alveolar macrophages reached a maximum level of 1.44 mg/l x 10(8) cells 72 h after injection. It was confirmed by means of a wavelength dispersive x-ray analyzer that fluorine atoms were present in the vacuolated alveolar macrophages. The peroxidase activity of the PFC-phagocytizing macrophages suggest that monocytes phagocytize PFC particles in the circulation and migrate to the alveolar space. This study shows that the monocyte/macrophage system is related to one mechanism for excretion of PFC after intravenous injection of PFC emulsions.

Animals↗
PubMed1989

Fibrinolytic and amidolytic activities of elastase-and chymotrypsin-like proteases in spleen and leukocytes of some mammals.

Nonplasmin-mediated fibrinolytic activities were extracted with 2 M NaCIO4 from the spleen and leukocytes of nine species of mammals. The amidolytic and fibrinolytic activities of extracts were measured using Suc-Ala-Tyr-Leu-Val-pNA for elastase-like protease (ELP) and Suc-Tyr-Leu-Phe-pNA (or Suc-Ile-Pro-Phe-pNA) for chymotrypsin-like protease (CLP). ELP and the fibrinolytic activity in the human spleen and leukocytes exhibited the highest values among the nine species. The relative order of amidolysis by CLP was as follows: hamster greater than rat greater than mouse greater than dog in the spleen and hamster greater than rat = ox greater than dog in leukocytes. Neither fibrinolytic nor amidolytic activity was measurable in spleens and leukocytes of pigs and rabbits. The ratios of ELP to CLP activity in the spleen or leukocytes of each of the species varied significantly from those observed in humans. The amidolytic activity of the spleen in control mice was low; however, that of mice which had been intraperitoneally inoculated with sarcoma 180 cells was enhanced and further accompanied by an increase in the number of granulocytes and in fibrinolytic activity. These results suggest that the enhancement of spleen amidolytic and fibrinolytic activities is induced by an increase of granulocytes in the circulation.

Animals↗
PubMed1989

Changes in hyperfrontality of cerebral blood flow and carbon dioxide reactivity with age.

We evaluated the topographic distributions of regional cerebral blood flow in 51 normal subjects (mean age 41 years) by the xenon-133 inhalation technique. Forty-five of these subjects were divided by age into young normals less than 30 years old (mean age 24 years), middle-aged normals 30-50 years old (mean age 40 years), and elderly normals greater than 50 years old (mean age 62 years); there were 15 subjects in each group. The distributions of vascular CO2 reactivity to hypocapnia were also evaluated in 20 of the normal subjects (mean age 34 years), including 11 younger normals less than 30 years old (mean age 24 years) and nine older (middle-aged or elderly) normals greater than or equal to 30 years old (mean age 45 years). The hyperfrontal distribution of regional cerebral blood flow observed in the young and middle-aged normals was not observed in the elderly normals. The hyperfrontal distribution of vascular CO2 reactivity observed in the younger normals was absent in the older normals. In addition, the correlation between regional cerebral blood flow and vascular CO2 reactivity observed in the younger normals was disturbed in the older normals. The data show a hyperfrontal distribution of regional cerebral blood flow in normal subjects that diminishes during the fifth and sixth decades, along with a distribution of vascular CO2 reactivity in younger normal subjects that is not homogeneous throughout the frontoparietal regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1989

Amino acids and peptides. XXV. Application of newly developed beta-1- and beta-2-adamantylaspartates to peptide synthesis by solid phase and conventional solution methods.

Newly developed beta-1- and beta-2-adamantylaspartates [H-Asp(O-1-Ada)-OH and H-Asp(O-2-Ada)-OH] were applied to the synthesis of a C-terminal octapeptide of the beta-subunit of human chorionic gonadotropin (hCG) by a conventional solution method and a hexacosapeptide of the alpha-subunit of insulin receptor (30-55) by a solid-phase method with the objective of suppressing aspartimide formation during the synthesis of aspartylpeptides. The 1-Ada and 2-Ada groups were confirmed to be useful protecting groups for the beta-carboxyl function of the Asp residue.

Adamantane↗
PubMed1989

Amino acids and peptides. XXIV. Synthesis of Neurospora crassa metallothionein and related cysteine-containing peptides and examination of their heavy metal-binding properties.

A pentacosapeptide corresponding to the entire amino acid sequence of Neurospora crassa metallothionein and several related cysteine-containing peptides were synthesized by the conventional solution method and their heavy metal-binding properties were examined. The Cu2+- or Cu+-binding properties of the various peptides were similar to each other, whereas the Cd2+-binding properties of these peptides were fairly structure-dependent.

Amino Acid Sequence↗
PubMed1989

Synthesis of tripeptide chloromethyl ketones and examination of their inhibitory effects on plasmin and plasma kallikrein.

With the aim of obtaining selective synthetic inhibitors of plasmin and plasma kallikrein, D-Ile-Phe-Lys-CH2Cl, Ile-Phe-Lys-CH2Cl, D-Ile-Phe-Arg-CH2Cl and Ile-Phe-Arg-CH2Cl were synthesized and their inhibitory activity against plasmin, plasma kallikrein and other trypsin-like serine proteinases was examined. Among them, D-Ile-Phe-Arg-CH2Cl exhibited a highly selective inhibitory activity against plasma kallikrein, yet D-Ile-Phe-Lys-CH2Cl exhibited nearly the same order of inhibitory activity against plasmin as well as plasma kallikrein.

Amino Acid Chloromethyl Ketones↗
PubMed1989

[Determination of isepamicin in the eluates from the dried blood spots on filter paper for monitoring of blood levels in a guinea-pig].

In general, collection of serial blood samples from small experimental animals is difficult in terms of sampling site and operation technique. To overcome these problems, a simple reproducible method has been improved by the use of filter papers. Whole blood obtained by venipuncture from the ear vein of guinea-pig was spotted onto a filter paper. Isepamicin in the dried blood spot was extracted with 0.5 M Na2HPO4 buffer by incubation and determined by fluorescence polarization immunoassay. Linearity was established over the range of 5-150 micrograms/ml by using only 100 microliters of whole blood. Consequently its accuracy and precision were good, with mean coefficient of variation of less than 5%. The method described here correlates well with a conventional sampling method and could be used for the pre-clinical study of isepamicin blood levels of individual guinea-pigs. This method is suitable for the simultaneous measurement of aminoglycoside antibiotics or physiological parameters after the administration of aminoglycoside antibiotics for the pharmacokinetics study.

Animals↗
PubMed1989

[Directed forgetting in rats using the radial arm maze].

The present experiments investigated whether rats could selectively retain the necessary spatial information and forget the unnecessary one in the radial arm maze task. In Experiment 1, rats were trained in a directed forgetting preparation in which the test choice was made following the R-cue and not following the F-cue. The performance on the probe tests, in which the test choice runs were given following the F-cue, was not affected by the F-cue and it was the same as on the R-cued trials. In Experiment 2, rats were trained in an intertrial-interference preparation in which R-cued and F-cued forced choices were run successively in a random order. In the test choice, rats obtained reinforcers if they avoided the R-cued arms. The analyses of performance of the test choices revealed that rats didn't utilize these instructional cues and consistently adopted a win-shift strategy. These findings suggest that the performance of the rats in the radial arm maze is highly inflexible.

Animals↗
PubMed1989

[A comparison of win-shift and win-stay performance of rats in a radial arm maze].

The purpose of the present experiment was to compare the performance of rats in a win-shift task and a win-stay task in a radial arm maze. To this end, three experiments were conducted using a variety of procedures. In general, the win-shift task required the rats to choose the unvisited arms and the win-stay task required the rats to return the visited arms. In Experiment 1, a free-choice memory recognition procedure was used, and in Experiments 2 and 3, a forced-choice memory recognition procedure was used. All three experiments showed that in the win-shift task, rats rapidly learned the task and performed well whereas in the win-stay task, the rats consistently showed a chance-level performance despite of the prolonged training. In addition to these findings, when the tasks were reversed (i.e. from the win-shift to the win-stay, and vice versa), the rats still showed a response strategy previously adopted (Experiment 3). These findings seem to be important in considering the characteristics of spatial memory in rats.

Animals↗
PubMed1989

Fatal graft-versus-host disease following transfusion during open heart surgery.

We report fatal transfusion-associated graft-versus-host disease (GVHD) in a patient who was not severely immunosuppressed. A 58-year-old man received 800 ml of fresh whole blood from his son and an unrelated volunteer donor during open heart surgery. On the 10th day after the operation, he suddenly had a high fever, followed by generalized skin rash and liver dysfunction. Pancytopenia due to bone marrow aplasia developed a week later. A skin biopsy revealed a cutaneous lesion highly compatible with acute GVHD. The patient did not respond to high-dose methylprednisolone therapy, and died of multiple organ failure on the 18th day after the operation.

Graft vs Host Disease↗
PubMed1989

Fluorescence polarization immunoassay of gentamicin or netilmicin in blood spotted on filter paper.

In this improved simple method for determination of aminoglycoside antibiotics in dried-blood spots on filter paper, gentamicin or netilmicin is recovered from the blood spot most effectively by incubation for 60 min in an ultrafiltration tube containing 500 microL of 0.5 mol/L Na2HPO4 buffer. The eluates from the paper are centrifuged, then transferred to an Abbott TDx cartridge for measurement of gentamicin or netilmicin by fluorescence polarization immunoassay. The dried sample on paper is stable for about eight days at ambient temperature. Intra-assay CVs for gentamicin and netilmicin are less than 8.5% and less than 6.1%, respectively. Analytical recovery of gentamicin and netilmicin from the paper exceeded 90%. This method permits simple blood collection and monitoring of the therapeutic concentration of gentamicin or netilmicin in serum, particularly that of newborn infants and small children.

Blood Stains↗
PubMed1988

Separation of current- and voltage-dependent inactivation of calcium current in frog sensory neuron.

The inactivation process of the calcium current was studied in frog dorsal root ganglion cells using a newly developed 'concentration clamp' technique, and an inactivation component independent of Ca influx was separated from the Ca-dependent component. The neuron was first placed in Ca-free solution, and pre-pulses of various amplitude were applied, thereby inducing depolarization without the Ca influx. Successive test pulses were applied immediately after a rapid exchange to a solution containing normal Ca. The amount of inactivation under this condition was much smaller than that measured when both pre- and test pulses were applied in the normal solution, and reached a steady level on pre-pulses over +50 mV. We suggest that the inactivation process of the Ca current consists of two components, i.e. a dominant component which is dependent on Ca influx, and a smaller one which is presumably voltage-dependent.

Animals↗
PubMed1988

Semiquantifying regional cerebral blood flow by 123I-amphetamine (IMP) SPECT in cerebrovascular disorders: correlations with CBF indices by 133Xe inhalation method.

To examine the capacity of detecting regional cerebral blood flow (rCBF) disturbances in stroke, measurements with 133Xe inhalation and 123I-amphetamine (IMP) SPECT were performed within 1-2 days in 19 patients. IMP SPECT images in transverse sections consisting of outer and inner areas were correlated with 32 regions of 133Xe rCBF. 133Xe rCBF was assessed by ISI, CBF15, and F1. Inter hemispheric ratio correlation showed outer IMP uptake correlated better with 133Xe CBF indices than the inner one. With higher ratios of 133Xe rCBF. IMP uptake ratios were variable, suggesting less usefulness of this parameter in evaluation of mild ischemia. Values of IMP in outer regional hypo and hyperemic areas correlated better with those of 133Xe rCBF than the inner ones. In regional ratios of hypo and hyperemic areas from hemispheric mean, outer IMP uptake correlated with 133Xe CBF indices, reflecting regional disturbances of fast clearing tissue perfusion. Regression lines between ratios in 133Xe CBF and IMP uptake were located below one to one correlation, and dissociated more for hyperemic regions. IMP SPECT correlated better with 133Xe rCBF for tissues with reduced perfusion but underestimated hyperemic regions as measured with the 133Xe method. The data suggest outer cerebral IMP uptake evaluated by SPECT could reflect flow disturbances in the brain cortex.

Adult↗
PubMed1988

Effects of Ca2+ on the transient outward current of single isolated Helix central neurones.

1. Single Helix neurones were studied under voltage-clamp conditions with internal perfusion in order to examine the contribution of internal and external Ca2+ and the effects of 4-aminopyridine (4-AP) on the transient outward current (IA). 2. In Na+ -free snail Ringer, replacement of external Ca2+ [( Ca2+]o) with equimolar Co2+ reduced the maximum amplitude of IA and induced a shift of the steady-state part of the IA inactivation curve (I-V curve), in a positive direction along the voltage axis when the neurone was internally perfused with K-aspartate. 3. In Ca2+ -free solutions, precipitation or chelation of internal Ca2+ [( Ca2+]i) by internal perfusion with KF or EGTA shifted the curve in a more negative direction without affecting the maximum amplitude of IA. Thus, the kinetics of IA are dependent not only upon [Ca2+]o, as previously suggested, but also upon [Ca2+]i. 4. In the presence of 4-AP the I-V curve for IA shifted in a hyperpolarizing direction and the maximal amplitude was reduced when the neurone was internally perfused with K-aspartate. However, 4-AP had little or no effect on the I-V relationship of IA when the neurone was internally perfused with the Ca2+ precipitating or chelating agent, KF or EGTA. These results suggest that the actions of 4-AP on IA are at least partly dependent upon [Ca2+]i.

4-Aminopyridine↗