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Biomedical subjects

M Tsuda

Publications and source records attributed to M Tsuda.

At least 307 records · Page 17Linked to original sources
PubMed1993

Effects of vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) on the spontaneous release of acetylcholine from the rat hippocampus by brain microdialysis.

Vasoactive intestinal polypeptide (VIP) has been suggested to have a presynaptic effect on cholinergic terminals in the rat hippocampus, which results in an activation of acetylcholine (ACh) synthesis. Recently, a VIP-related novel peptide, pituitary adenylate cyclase activating polypeptide (PACAP) was isolated from the ovine hypothalamus, and we previously demonstrated in the rat that PACAP binding site densities were high in the hippocampus. In the present study, we investigated the effects of VIP and PACAP on the release of ACh from the rat hippocampus. We succeeded in detecting the spontaneous release of ACh from the dorsal hippocampus in the conscious rat using microdialysis and HPLC-ECD. VIP, PACAP38 and PACAP27 were applied through a microinjection cannula placed in a region adjacent to the tip of a microdialysis tube. Injections of VIP, PACAP38 and PACAP27 (12, 120 pmol) resulted in dose-related increases in ACh release. The ability to enhance ACh release was VIP > PACAP38 > PACAP27. The increased release of ACh caused by these peptides was highly calcium-dependent. Tetrodotoxin (10(-6) M) added to the perfusion medium significantly reduced both the release of ACh enhanced by these peptides and the basal release. The present results suggest that VIP, PACAP38 and PACAP27 presynaptically stimulate cholinergic activity in the hippocampus, which may be reflected by an increase in ACh synthesis to maintain releasable terminal stores of ACh.

Acetylcholine↗
PubMed1993

Isolation and characterization of a high molecular weight type IV collagenase isolated from human carcinoma tissue.

A proform of high molecular weight type IV collagenase was isolated and purified 1230-fold from human metastatic carcinoma tissue. Like matrix metalloproteinases (MMPs), the enzyme was activated by trypsin and degraded type IV collagen and gelatin at a neutral pH, the activity was inhibited by EDTA and o-phenanthroline. However, the molecular weight was much higher than MMPs which degraded type IV collagen, gelatinase A (MMP-2; 72 kDa gelatinase/type IV collagenase) (EC 3.4.24.24), gelatinase B (MMP-9; 92 kDa gelatinase/type IV collagenase) (EC 3.4.24.35), stromelysin-1 (MMP-3; 57 kDa) (EC 3.4.24.17) and stromelysin-2 (MMP-10; 57 kDa) (EC 3.4.24.22). The other significant difference from MMPs was that the enzyme was not activated by 4-aminophenylmercuric acetate nor inhibited by TIMP. Taking together these results, this high molecular weight type IV collagenase might be a newly found enzyme different from MMPs or might have the same configuration as MMPs already reported.

Collagen↗
PubMed1993

Infrared studies of octopus rhodopsin. Existence of a long-lived intermediate and the states of the carboxylic group of Asp-81 in rhodopsin and its photoproducts.

The infrared absorption spectra of octopus rhodopsin and its photoproducts have been observed at 282K and 210K under irradiation of blue and orange light in a neutral condition. The acid metarhodopsin-minus-rhodopsin and lumirhodopsin-minus-rhodopsin difference spectra have been obtained. A new intermediate (called transient acid metarhodopsin) with a lifetime of about 5 s has been found to exist prior to acid metarhodopsin. The present results, together with the data obtained previously, give information on the state of the carboxylic group in the side chain of Asp-81, which is the only acidic amino-acid residue in the part of opsin buried inside the membrane. This carboxylic group is protonated throughout the transformation series, but its state changes on going from transient acid metarhodopsin to acid metarhodopsin. It is probable that these two photoproducts are different from each other only in the opsin moiety.

Animals↗
PubMed1993

Regional distribution of pituitary adenylate cyclase activating polypeptide (PACAP) in the rat central nervous system as determined by sandwich-enzyme immunoassay.

We investigated endogenous levels of a novel peptide, pituitary adenylate cyclase activating polypeptide (PACAP), in the rat central nervous system. The amount of PACAP was measured by means of highly specific and sensitive sandwich-enzyme immunoassay. This assay system following HPLC analysis revealed that PACAP38 was a major portion of the total PACAP immunoreactivity and PACAP27 levels were negligibly low in the brain. Therefore, we measured the amount of PACAP38 in 62 regions punched out from frozen tissue sections. High amounts of PACAP38 were found in the lateral septal nucleus (intermediate part), diagonal band, central amygdaloid nucleus, several parts of the hypothalamus (suprachiasmatic, supraoptic, periventricular and arcuate nuclei), central gray, interpeduncular nucleus and dorsal raphe. The suprachiasmatic, paraventricular and periventricular hypothalamic nuclei showed the highest levels. A moderate amount of the peptide was observed in the lateral septal nucleus (dorsal part), medial septal nucleus, medial amygdaloid nucleus, thalamus (paraventricular, paratenial, central medial, ventromedial, reuniens and rhomboid nuclei), hypothalamus (lateral hypothalamic area and mammillary body), ventral tegmental area, interfascicular nucleus and in the locus coeruleus. Such a distribution of endogenous PACAP38 did not parallel the localization of PACAP binding sites which we had demonstrated recently. Moreover, the topographical distribution of PACAP38 observed in the present study differed from that of VIP which had been previously reported. The present results suggest that PACAP38 may have a neurotransmitter/neuromodulator role which is different from that of VIP in the central nervous system.

Animals↗
PubMed1993

Comparison between diurnal distribution of onset of infarction in patients with acute myocardial infarction and circadian variation of blood pressure in patients with coronary artery disease.

We analyzed the diurnal distribution of the onset of infarction in 636 patients with acute myocardial infarction (MI) and compared it with the circadian variation of blood pressure in 57 patients with coronary artery disease (CAD). In addition, we studied the modification of the circadian blood pressure variation during treatment with antianginal medications in 20 patients with CAD. A marked diurnal periodicity (p < 0.05) was observed for the onset of MI, with peaks seen in the late morning, late evening, and very early morning. The blood pressure in the patients with CAD was elevated in the morning, reduced in the late evening, and was the lowest in the very early morning. The peaks of onset of infarction temporally corresponded to the characteristic feature of blood pressure profile observed in the patients with CAD, that is, the morning rise, the late evening decline, and the very early morning reduction. Antianginal medications significantly reduced the blood pressure, not only during the day (p < 0.02) but also at night (p < 0.05). These observations suggest that the decline in blood pressure, as well as the morning surge in blood pressure, may be closely related to the onset of MI. Therefore, when treating patients with CAD with antianginal medications which can potentially reduce blood pressure, the effects on the circadian variation of blood pressure should be considered.

Blood Pressure↗
PubMed1993

Costimulation-induced rounding in Tetrahymena thermophila: early cell shape transformation induced by sexual cell-to-cell collisions between complementary mating types.

Mixing of starved cells of complementary mating types of Tetrahymena thermophila induces shortening of their longitudinal length within 10 min of mixing. This early morphogenetic transformation in preconjugant sexual interaction (costimulation period) was named "costimulation-induced rounding" (CIR). CIR is the earliest morphological change that has ever been found in the costimulation period and differs from "synchronous rounding" in the vegetative cell cycle, because CIR cells are still able to form food vacuoles, while cells in synchronous rounding do not have this ability. When sexual cell-to-cell collisions between two mating types were hampered by unidirectional stirring for 20 min after mixing of the two mating types, both CIR and conjugation were delayed by 20 min. When secreted materials needed for the onset of costimulation were removed by washing the cells with 10 mM Tris-HCl, pH 7.4, before mixing the two mating types, both CIR and conjugation were delayed by about 30 min. CIR-like rounding was not induced by cell-free medium either from the opposite mating type or from mixed costimulated cells. These results indicated that CIR is induced when cells are activated to form conjugating pairs by cell-to-cell collisions between complementary mating types in the presence of secreted molecules.

Animals↗
PubMed1993

Estimation of anterior infarct size with body surface QRST integral maps in the presence of abnormal ventricular activation sequence in dogs.

The possibility of estimating infarct size with body surface QRST integral (IQRST) maps was investigated in dogs. IQRST maps were constructed from 87-lead body surface ECGs, which were recorded 1 week after the production of anterior myocardial infarction during artificial pacing that simulated normal conduction, left bundle branch block, and Wolff-Parkinson-White syndrome in 11 dogs. Small differences were observed between the IQRST maps of the normal conduction and left bundle branch block models (r = 0.93, root mean square difference = 8.71 mVmsec) and between the normal conduction and Wolff-Parkinson-White models (r = 0.96, root mean square difference = 6.03 mVmsec). Summation of the QRST integral values over the body surface leads (QRST index) inversely correlated with infarct size in all three conductions models: r = 0.91 (p < 0.001) in the normal conduction model; r = -0.81 (p < 0.001) in the left bundle branch block model; and r = -0.86 (p < 0.001) in the Wolff-Parkinson-White model. These results show that IQRST maps permit noninvasive estimation of infarct size, even in the presence of abnormal activation sequences.

Animals↗
PubMed1993

Diagnostic value of postexercise systolic blood pressure response for detecting coronary artery disease in patients with or without hypertension.

To evaluate the diagnostic value of the postexercise systolic blood pressure (SBP) response for detecting and evaluating the presence of coronary artery disease (CAD), treadmill testing was conducted in 130 subjects with normal blood pressure and 51 patients with hypertension, each of whom underwent selective coronary angiography. A total of 48 subjects with normal blood pressure and 27 patients with hypertension had no significant narrowing of the coronary artery (control subjects), whereas 82 subjects with normal blood pressure and 24 patients with hypertension had significant narrowing (patients with CAD). The postexercise SBP response was defined on the basis of the SBP ratio (i.e., the SBP at 3 minutes of recovery divided by that at peak exercise). An SBP ratio that exceeded 0.90 (cutoff point for discriminating control subjects from patients with CAD) was considered to be an abnormal SBP response. In the subjects with normal blood pressure, the abnormal SBP response identified CAD as accurately as did ST-segment depression. In the patients with hypertension, the diagnostic accuracy was increased significantly by combining the abnormal SBP response and ST-segment depression (p < 0.01). The SBP ratio increased with the number of diseased coronary arteries. Ten of the 14 patients with a narrowing of the left main coronary artery had an SBP ratio higher than 1.00. The postexercise SBP response may be useful for detecting CAD in patients with and without hypertension and for evaluating the severity of CAD.

Blood Pressure↗
PubMed1993

Preservation of the umbilical cord at the primary fascial closure in infants with gastroschisis.

Recently, the survival of patients with gastroschisis has been dramatically improved and it has reached more than 90%. Over the last 10 years, 20 of 21 cases (95%) survived in our hospital. We have been using the primary fascial closure of the abdominal wall as a standard operative procedure. The umbilical cord was usually excised at the operation in order to secure the suture line and prevent wound infection. The survivors sometimes complained of the absence of the umbilicus. However, it was somewhat difficult to create a new umbilicus later by use of the surrounding skin. In the last five cases, we tried to carry out the primary fascial closure with preservation of the umbilical cord. All patients could obtain good cosmetic results with near-normal appearance. Omphalitis or cellulitis was never observed, but a small umbilical hernia occurred in one case.

Esthetics↗
PubMed1993

Fate and behavior of genetically labeled cerebellar cells after transplantation into mouse cerebellum.

A foreign gene coding the bacterial enzyme, chloramphenicol acetyltransferase (CAT), was introduced into a primary culture of the mouse cerebellar primordium by a retrovirus vector which harbors the neomycin-resistant gene. Following selection of the gene-transferred cells based on neomycin resistance, most of the selected cells expressed the CAT gene product as well as a marker for astrocytes, glial fibrillary acidic protein (GFAP), when examined immunocytochemically. These cells were transplanted into the adult mouse cerebellum, and the surviving cells were examined immunohistochemically by marking them with anti-CAT antibody. The distribution of CAT-immunopositive cells coincided with that of GFAP-immunopositive cells observed in serial sections of grafted sites at 10 days after transplantation. Some of the transplanted CAT-immunopositive cells extended processes and exhibited the morphological appearance of fibrous astrocytes. Migration of the genetically labeled cells into the host molecular layer was also observed and the morphological plasticity of the differentiated primary cells was shown according to the grafted sites. These results indicate that stable marking of cells for grafting can be accomplished by retrovirus-mediated introduction of a foreign gene into the primary culture, and that the fate and behavior of the labeled donor cells can be analyzed immunohistochemically following transplantation into neural tissue.

Animals↗
PubMed1993

Neurite outgrowth from N18TG2 neuroblastoma induced by H-7, a protein kinase inhibitor, in the presence of colchicine.

Our previous studies have demonstrated that the protein kinase inhibitor H-7 promotes neurite outgrowth from mouse neuroblastoma N18TG2 cells as well as from primary cerebellar cells, and also that the neurites induced by H-7 were more tolerant of colchicine (COL) than those induced by dibutyryl cAMP (dB-cAMP). In the present study, we tested the effects of H-7 and dB-cAMP on neurite growth from N18TG2 cells in the presence of COL. We found that only H-7 promoted neurite formation in the presence of COL. The percentage of cells with neurites induced by H-7 in the presence of COL (H-7 + COL) was similar to that induced by H-7 alone. The neurites induced by H-7 + COL grew straight. They were very thin (less than 1 micron in diameter) and had round varicosities, as did the neurites induced by H-7 alone. By transmission electron microscopy, the neurites induced by H-7 + COL were found to contain longitudinally arranged intermediate filaments (IF). Microtubules (MT) were not observed within the neurites. We also examined the effect of cytochalasin B (CB) on the neurites induced by H-7 + COL and by H-7 alone. The neurites induced by H-7 + COL were tolerant to CB, but those induced by H-7 were resorbed completely within 24 h after CB was applied. Neurites tolerant to CB contained longitudinally IF. Simultaneous application of CB with H-7 + COL or with H-7 alone did not induce neurite formation.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

Production of immunoreactive pituitary adenylate cyclase activating polypeptide (PACAP) by human neuroblastoma cells, IMR-32: detection and characterization with monoclonal and polyclonal antibodies against different epitopes of PACAP.

Sensitive and specific two-side enzyme immunoassays (two-site EIAs) for pituitary adenylate cyclase activating polypeptides, PACAP38, and PACAP27, have been established using six monoclonal antibodies against PACAP38, and a rabbit antibody against a C-terminal portion of PACAP27. In extracts of rat hypothalamus, these EIAs detected not only PACAP38 and PACAP27 but also an immunoreactive (ir-) PACAP lacking an epitope of a monoclonal antibody, PA-1C, which recognizes the C-terminal portion of PACAP38. By the use of these EIAs, it was found that one of the human neuroblastoma cell lines, IMR-32, produced ir-PACAP. In reverse-phase (RP-)HPLC, intracellular and extracellular ir-PACAPs were separated into two peaks, of which one was eluted at a position close to that of PACAP38 and the other in rather hydrophobic fractions. Those ir-PACAPs also lacked PA-1C epitope of PACAP38. SDS-PAGE and immunoblot analysis of the two peaks of the RP-HPLC indicated that they consisted of several components including those with apparent molecular weights of 6.5 k and 10 k for the first peak ir-PACAP, and 14 k and 20 k for the second peak ir-PACAP. These results indicate that IMR-32 produces a precursor of PACAP and related peptides generated in various processing steps. Although the significance of the modification in the C-terminus of PACAP38 is unknown, IMR-32 may be a cell line useful for studying the regulation of the biosynthesis of PACAP.

Animals↗
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

Genetic transformation in Helicobacter pylori.

Genetic transformation in Helicobacter pylori was investigated by using its chromosomal and plasmid DNAs. Six out of the eight strains exhibited the natural competence for incorporation of H. pylori chromosomal DNA, and all the strains incorporated the donor DNA efficiently by washing and concentrating the cells with a glycerol solution. The much higher frequency of transformation was obtained in each strain by means of electroporation. Electroporation experiments were also conducted by use of the recombinant DNAs consisting of the H. pylori and Escherichia coli plasmids as the donors, and the occurrence of the homologous recombination was demonstrated between the incoming H. pylori plasmid-derived region and the corresponding region of the originally residing plasmid in H. pylori.

Chromosomes, Bacterial↗
PubMed1993

Clinicopathological correlations of visual depth perception in patients with cerebrovascular disease.

Visual depth perception in 100 patients with cerebrovascular disease was evaluated using the Titumus stereotest. Twelve patients showed depth perception impairment. CT scans revealed that the lesion was located on the right hemisphere in 6 patients and on the left hemisphere in 3 patients, and that the remaining 3 patients had multiple infarctions. 123I SPECT was performed in 7 patients with moderate to severe depth perception impairment, of whom 6 patients showed a reduced blood flow in the posterior half of both the right and left cerebral hemispheres. Moderate to severe impairment of depth perception was more frequently observed in patients with a lesion in the right hemisphere or in the posterior half of either hemisphere.

Aged↗