Search PubMed⌕ Search

Biomedical subjects

T Tsuchiya

Publications and source records attributed to T Tsuchiya.

At least 379 records · Page 21Linked to original sources
PubMed1993

Purification and characterization of two metalloproteinases from squid mantle muscle, myosinase I and myosinase II.

Metalloproteinases, myosinase I and myosinase II, that hydrolyze the heavy chain of myosin, were purified from squid mantle muscle. Myosinase I does not hydrolyze other muscle proteins, casein, haemoglobin, or MCA-substrates, while II hydrolyzes tropomyosin. Both myosinase I and myosinase II gave a single protein band on SDS-PAGE with a molecular mass of 16 and 20 kDa, respectively. Their activities were inhibited by EDTA and 1,10-phenanthroline, and II was also inhibited by EGTA. They could be reactivated with some divalent cations, I was especially reactivated with Co2+ and II especially with Zn2+. The optimum pH of both activities was 7.0; the optimum temperature for both was 40 degrees C. Myosinase I hydrolyzes myosin heavy chains to produce 130 and 90 kDa fragments. The N-terminal amino-acid sequence of the 90 kDa fragment indicates that myosinase I splits the myosin heavy chain between Ala-1161 and Thr-1162 in subfragment 2. Myosinase II hydrolyzes myosin heavy chain to produce 158 and 65 kDa fragments, and it splits between Glu-1381 and Thr-1382 in LMM. Myosinases I and II are most likely related to the metabolism of myosin in vivo.

Amino Acid Sequence↗
PubMed1993

Comparative studies of the toxicity of standard reference materials in various cytotoxicity tests and in vivo implantation tests.

Polyurethane films that contained various amounts of zinc diethyldithiocarbamate (ZDEC) and zinc dibutyldithiocarbamate (ZDBC) were prepared as standard reference materials (SRM). Using three cell lines of V79, L929, and Balb/3T3 cells, the cytotoxicity of the dithiocarbamates and the SRM films were compared by agar diffusion assay, filter diffusion assay, neutral red assay, cell growth assay, and colony assay. Among these in vitro cytotoxicity tests, colony assay was found to be the most sensitive method for detecting the cytotoxicity. The cytotoxic potentials of extracts from SRM films correlated well with the concentrations of ZDEC or ZDBC involved in SRM. When various rubber materials including SRM and surgical rubber latex materials were tested, cytotoxic potentials of these extracts were also correlated with the inflammatory tissue capsule thickness in short-term implantation tests. On the basis of these results, the SRM is judged to be useful for validating test sensitivity, and comparing the correlation between in vitro and in vivo responses.

3T3 Cells↗
PubMed1993

Rabbit eye irritation caused by wearing toxic contact lenses and their cytotoxicities: in vivo/in vitro correlation study using standard reference materials.

To clarify the relationship between eye irritancy and cytotoxic potential induced by irritant materials, we made lenses coated with standard reference materials (SRMs) prepared from various amounts of zinc diethyldithiocarbamate (ZDEC) and polyurethane (PU). Zinc diethyldithiocarbamate was classified as a mild irritant by the Draize eye irritation test. When ZDEC-SRM coated contact lenses were applied to rabbit eyes, Draize scores increased in proportion to both the ZDEC and PU concentrations used for coating. Furthermore, correlation with the cytotoxic potential (gamma = -0.93) was better than with lactate dehydrogenase (LDH) activities of tears from rabbit eyes wearing these coated lenses (gamma = 0.78). In conclusion, in vivo eye irritancy induced by wearing lenses could be estimated quantitatively with the cytotoxic potentials using a colony assay. Furthermore, we could compare different sensitivities caused by the same set of SRMs among three different sites of tissue. As a result, the order of sensitivity was eye > muscle >> skin.

3T3 Cells↗
PubMed1993

Measurement of transverse stiffness change during contraction in frog skeletal muscle by scanning laser acoustic microscope.

The scanning laser acoustic microscope (SLAM) was utilized to measure the change in the propagation velocity in the transverse direction during contraction in living skeletal muscles of the frog. The SLAM was operated at 100 MHz and interferograms were produced on a CRT in real time. The images of the interferogram were processed by image-analyzer and the propagation velocity was calculated from the shift of the interference line at rest and during contraction. In all the measurements (n = 15), the velocities during contraction were clearly slower (-7.6 m/s) than at rest and this means that the transverse stiffness decreased during contraction (-2.4 x 10(7) N/m2). The decrease in the propagation velocity preceded the increase in force by 30-40 ms after stimulation, suggesting that the decrease in the transverse stiffness reflects the basic molecular change in muscle contraction.

Animals↗
PubMed1993

A sensitive mouse lymph node assay with two application phases for detection of contact allergens.

A predictive test using mice for the identification of contact sensitizing chemicals was developed. Contact sensitizing activity is measured as a function of draining lymph node activation following application of test chemical. Experimental conditions for assessment of induced lymph node cell (LNC) responses have been optimized. BALB/c mice were initially treated with intradermal injections of test chemical in Freund's complete adjuvant emulsion. Five days after intradermal injection, mice were exposed topically to chemical in vehicle on the ears daily for 3 consecutive days. Next day following the final exposure, changes in lymph node weight, total cell number in the draining lymph nodes and LNC proliferation for 24 h culture were assessed. The performance of the method was evaluated with ten sensitizing chemicals and a non-sensitizing irritant, sodium lauryl sulfate (SLS). The LNC proliferation induced by combination of intradermal injection and topical application of sensitizing chemicals was more clearly increased than that following only topical application. With the single exception of sulfanilic acid, the method developed was able to detect the sensitizing capacity of chemicals that failed to induce sensitization in the local lymph node assay. Under the conditions used, SLS did not induce measurable lymph node responses. These results suggest that the mouse lymph node assay can provide a sensitive screening test for weak to moderate sensitizers. In addition, the assay offers the advantages of objective and quantitative endpoints, and is suitable for the evaluation of colored or irritant chemicals.

Administration, Topical↗
PubMed1993

The complete nucleotide sequence of African horsesickness virus serotype 4 (vaccine strain) segment 4, which encodes the minor core protein VP4.

The complete sequence of RNA segment 4 of African horsesickness virus serotype 4 (AHSV-4) vaccine strain was determined from the full-length cDNA clone inserted into pBR322. The RNA is 1978 bp long (M(r) 1.27 x 10(6)) and contains an open reading frame encoding a protein of 642 amino acids (M(r) 75826) with a net charge of +10 at neutral pH. The 5' and 3' termini of AHSV-4 segment 4,5'GTTTAT... and ...CCTTAC3', were different from orbivirus characteristic terminal sequences, being 5'GTTAAA... and ...ACTTAC3'. A comparison of the sequence of AHSV-4 segment 4 with that of bluetongue virus (BTV) serotype 10 revealed 55.4% nucleotide similarity and 48.5% amino acid similarity. In addition, Northern blot hybridization showed that the full-length AHSV-4 segment 4 cDNA cross-hybridized well with the corresponding genes of serotype 1, 2, 3, 4 and 7 but slightly with serotype 5, 6 and 8 of attenuated AHSV.

African Horse Sickness Virus↗
PubMed1993

Morphological aspects of Achacin-treated bacteria.

1. The morphology of bacteria treated with the bactericidal glycoprotein, Achacin, purified from the giant African snail, Achatina fulica Férussac, has been studied. 2. Achacin lengthens the bodies of Escherichia coli by three to seven times. 3. Achacin damages the surface of Staphylococcus aureus and sinks the cytoplasmic membranes into the cytoplasm. 4. Achacin causes neither the leakage nor the destruction of cells.

Escherichia coli↗
PubMed1993

Erythropoietin 5'-flanking sequence-binding protein induced during hypoxia and cobalt exposure.

The 5'-flanking region of the human erythropoietin (Epo) gene contains a 0.14-kb sequence that is conserved in the Epo gene from mouse and located within a promoter that is activated under hypoxic conditions such as anemia. Using a fragment containing this sequence in DNA mobility shift assays, we found that specific DNA-binding proteins were induced in mouse kidney nuclei under anemic hypoxia. Using synthetic double-stranded oligonucleotides that contain this sequence, the essential binding site was defined to be the -40 to -20 region upstream of the transcription initiation site in the human Epo gene. By DNA affinity chromatography using a column with the immobilized 5'-flanking sequence, two inducible binding proteins with apparent molecular masses of 55 and 45 kDa were identified in the nuclei of mouse kidney and liver under anemic hypoxia. These binding proteins were also induced during cobalt exposure.

Anemia↗
PubMed1993

Introduction of a series of alkyl thiomaltosides, useful new non-ionic detergents, to membrane biochemistry.

We synthesized a series of non-ionic detergents, alkyl thiomaltosides, and investigated their properties and usefulness. We solubilized membrane proteins of Vibrio parahaemolyticus using the detergents. With octyl thiomaltoside, nonyl thiomaltoside, decyl thiomaltoside, or undecyl thiomaltoside, we observed satisfactory solubilization of the membrane proteins. Alkyl thiomaltosides possessing longer alkyl chains showed better solubilization than ones possessing shorter chains. H(+)-translocating ATPase (F0F1), which is localized in the cytoplasmic membrane (inner membrane), was solubilized with the detergents, and the solubilized enzyme showed much higher specific activity than that solubilized with octyl glucoside or heptyl thioglucoside, other useful non-ionic detergents. 5'-Nucleotidase, which seems to be an outer membrane protein, was also efficiently solubilized with the alkyl thiomaltosides. Membrane proteins of Escherichia coli were also efficiently solubilized with the detergents. Octyl thiomaltoside and nonyl thiomaltoside were removed fairly rapidly on dialysis. Decyl thiomaltoside was removed slowly, and undecyl thiomaltoside and dodecyl thiomaltoside were difficult to remove by dialysis.

5'-Nucleotidase↗
PubMed1993

Effects of FK506 and cyclosporine on dynamic insulin secretion from isolated dog pancreatic islets.

Pancreatic islet transplantation may be the most ideal treatment for patients with insulin-dependent diabetes mellitus. However, immunosuppressive agents such as cyclosporine A(CsA) and FK506, used for these transplanted patients have been reported to cause glucose intolerance. In the present study, we have compared the effects of CsA and FK506 on glucose-stimulated insulin release from the isolated dog pancreatic islets, which have been maintained in culture for 3 days after isolation. The isolated dog pancreatic islets, pretreated for 24 hr with either CsA or FK506 (1, 10, and 100 nM), were perifused with 16.7 mM glucose. Pretreatment with both drugs suppressed glucose-stimulated insulin secretion in a dose-dependent fashion. CsA (100 nM), which is a therapeutically relevant concentration, significantly suppressed both the first and second phases of glucose-stimulated insulin release compared with 100 nM FK506. These findings suggest that, with a therapeutically relevant concentration, FK506 may be less toxic than CsA against pancreatic islets in patients with organ or cell transplantation.

Animals↗
PubMed1993

Additive induction of Egr-1 (zif/268) mRNA expression in neuroblastoma x glioma hybrid NG108-15 cells via cholinergic muscarinic, alpha 2-adrenergic, and bradykinin receptors.

Administration of carbachol, noradrenaline, and bradykinin induced Egr-1 mRNA expression within 1 h in mouse neuroblastoma x rat glioma hybrid NG108-15 cells. With specific receptor antagonists, the Egr-1 inductions by carbachol and noradrenaline were shown to be mediated via cholinergic muscarinic and alpha 2-adrenergic receptors, respectively. At their saturation levels for Egr-1 induction, the two agonists had additive effects when added together, but no prolongation of the effect on Egr-1 induction was observed. Addition of carbachol or noradrenaline 6 h after primary stimulation with carbachol or noradrenaline did not result in secondary Egr-1 induction, probably because of receptor desensitization. On the other hand, bradykinin consistently had an additive effect on Egr-1 induction, irrespective of the time of its addition, suggesting that the signal pathways for Egr-1 induction by carbachol or noradrenaline and by bradykinin are different. Treatment of cells with pertussis toxin or cholera toxin strongly inhibited Egr-1 induction by carbachol or noradrenaline but only partially inhibited the induction by bradykinin. Thus, the signals transduced in NG108-15 cells by different neurotransmitter receptors appear to have different effects on Egr-1 induction, depending on the times of stimulation and the combinations of receptors stimulated.

Animals↗
PubMed1993

Evaluation of contact sensitivity of rubber chemicals using the murine local lymph node assay.

The sensitizing abilities of 4 rubber additives, tetramethylthiuram disulfide (TMTD). 2-mercaptobenzothiazole (MBT), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) and zinc diethyldithiocarbamate (ZDEC), were evaluated using the murine local lymph node assay. Exposure to IPPD induced a significant increase of lymph node cell proliferation in the draining lymph nodes even at a low concentration. Exposure to TMTD and MBT induced moderate proliferative responses, while ZDEC induced a weak proliferation even at the higher concentrations. The sensitizing potency of each chemical was described in terms of the concentration that increased lymph node cell proliferation by a factor of 2 over that in the vehicle-treated control group. The concentrations of IPPD, TMTD, MBT and ZDEC were 0.14%, 0.35%, 4.2% and > 10%, respectively.

Animals↗
PubMed1993

Influence of irritants on lymph node cell proliferation and the detection of contact sensitivity to metal salts in the murine local lymph node assay.

Dimethyl sulfoxide (DMSO) and sodium lauryl sulfate (SLS) are known to cause irritation of the skin, and to enhance the penetration of chemicals into the epidermis. In the present study, the lymph node cell (LNC) proliferative response following exposure to irritants, such as SLS and DMSO, was examined in the murine local lymph node assay (LLNA). Exposure to DMSO or SLS aqueous solution induced a small increase in lymph node cell proliferation compared with aqueous solution alone. Exposure to SLS in DMSO caused a significant increase in LNC proliferation. Further, the effect of addition of the irritants in a vehicle on the detection of contact sensitivity to metal allergens was examined. Application of potassium dichromate and nickel sulfate in DMSO or SLS aqueous solution caused increases in LNC proliferation. Exposure to metal allergen with SLS in DMSO also induced a significant LNC proliferative response, but did not induce a significant increase in stimulation index (increase in 3H-thymidine incorporation relative to vehicle-treated control group). This was because of increased 3H-thymidine incorporation following exposure to SLS-DMSO in the control group. These results suggest that irritants enhance the LNC proliferative responses to metal allergens. The use of SLS in aqueous solution is effective for the detection of sensitivity to water-soluble allergens, such as metal allergens, in the LLNA, as well as the use of DMSO as an application vehicle.

Animals↗
PubMed1993

[Current status of Pasteurella multocida infection in Japan].

Recently, the case reports of Pasteurella multocida infection has been increasing in Japan. In 1989, the Japanese Government, Veterinary Sanitation Division, Ministry of Health and Welfare officially communicated this infection as a zoonosis to related institutions. The current status of Pasteurella multocida infection is not well known in Japan. Because of this, a nation wide questionnaire survey on Pasteurella multocida was conducted to clarify the status. A questionnaire was sent to 380 laboratories of the hospitals, and 258 (67.9%) replied. An infectious disease caused by Pasteurella multocida was found in Japan in 369 cases in 115 (44.6%) of 258 hospitals, or an average of 3.2 cases per hospital. The 369 cases were broken down into 123 males (from 1 month old to 87 years old), 118 females (from 7 months old to 88 years old), and 128 patients whose sex was unknown. The incidence of the infections tends to increase year by year. This incidence is higher than our expectation. It is considered that the contact with pets will in increase the infection with this agents. The organism was isolated in as many as nineteen different body specimens, including the appendix and urine, which in Japan has not been reported as organs harboring this organism. Some of the nineteen cases were severely infected. This organism was isolated most often from the sputum (48.5%). Pus was the next most common site (27.1%). This order was reversed in the U.K. and the U.S.. Possible explanations for the reversal are given below.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Amyloid precursor protein is found in lysosomes.

The major component of Alzheimer's disease amyloid is a small polypeptide referred as the amyloid beta protein, which is derived from a larger precursor, amyloid precursor protein (APP). Cell fractionation and immunological studies on the APP molecule indicate that APP is localized either in the neuron and astrocyte and that the molecule is recovered from lysosomal fraction.

Amyloid beta-Protein Precursor↗
PubMed1993

Regional cerebral blood flow measured with N-isopropyl-p-[123I]iodoamphetamine and its redistribution in ischemic cerebrovascular disease.

BACKGROUND AND PURPOSE: The relation between the redistribution phenomenon and regional cerebral blood flow and its clinical significance were investigated in stroke patients. METHODS: Single-photon emission computed tomography studies using N-isopropyl-p-[123I]iodoamphetamine were performed on 16 patients (26 to 77 years old) with chronic infarction and 10 age-matched normal control subjects. Regional cerebral blood flow was quantitatively measured by a microsphere model, and the redistribution on delayed images was analyzed in ischemic lesions. RESULTS: Supratentorial mean cerebral blood flow and the ratio of gray matter to white matter in normal subjects were 52.7 +/- 5.0 mL/100 g per minute and 2.34, respectively. Low-activity areas of ischemic lesions on early images were classified into two abnormal zones, an infarct area and a peri-infarct area. These regions were characterized by regional blood flow averaging 9 to 20 mL/100 g per minute and 22 to 41 mL/100 g per minute, respectively. Redistribution, which was minimally present in the infarct area, was markedly enhanced in the peri-infarct area. After bypass surgery, we observed a significant increase of blood flow (+22%) in the peri-infarct area. CONCLUSIONS: The data indicate that the redistribution phenomenon depends on the maintenance of a minimal blood flow that would sustain cellular function and that this phenomenon is useful to evaluate bypass surgery in patients with chronic infarction.

Adult↗
PubMed1993

Mobile string-like thrombus on the calcified aortic valve in cardioembolic stroke--a case report.

The calcified aortic valve has been associated with being a possible source of emboli in cardioembolic stroke. However, thrombus on the calcified aortic valve has not been identified with two-dimensional echocardiography. A seventy-two-year-old woman with calcified aortic stenosis was admitted with brain embolism. She had not previously received any platelet antiaggregant or anticoagulant. At admission, two-dimensional echocardiography demonstrated a mobile string-like abnormal echo attached to the calcified aortic valve, which showed regression and enlargement repeatedly during admission. No symptoms or clinical data suggested infective endocarditis or nonbacterial thrombotic endocarditis. After commencement of antiplatelet therapy, the abnormal echo regressed and disappeared. She continued to take the medication for seven months and then discontinued. Three months later, she developed recurrence of stroke, and an abnormal echo on the calcified aortic valve was again detected by two-dimensional echocardiography. The authors believe that the abnormal echo on the calcified aortic valve was thrombus and that it was the embolic source. Calcified aortic valve may thus be a causative lesion for mobile string-like thrombus. Two-dimensional echocardiography should be performed repeatedly in patients with calcified aortic valve and brain embolism.

Aged↗