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Biomedical subjects

T Sakurai

Publications and source records attributed to T Sakurai.

At least 379 records · Page 21Linked to original sources
PubMed1995

Indications and options of nutritional treatment for Crohn's disease. A comparison of elemental and polymeric diets.

Several studies on enteral nutrition undertaken by our group led to the following findings: (1) A semielemental diet was as effective as an elemental diet in inducing remission. (2) A low-residue diet was useful for the maintenance of remission, with the effect depending upon the quantity given. (3) Intractability to enteral nutrition was found in patients with long-standing disease, in those with severe activity, and in those with colonic disease. Currently there is insufficient evidence to make specific recommendations for altering accepted indications for nutritional therapy.

Crohn Disease↗
PubMed1995

[Detection of Mycoplasma pneumoniae by using polymerase chain reaction and nonradioactive DNA probes].

Mycoplasma pneumoniae is the causative agent of primary atypical pneumoniae, and two distinct groups (I and II) have been established. Serological tests are relatively insensitive and the diagnosis by culture is time-consuming. This study was therefore undertaken to detect and to identify M. pneumoniae on culture media and in throat swab specimens by using polymerase chain reaction (PCR) and hybridization probes conjugated to alkaline phosphatase (Alp). Primer pairs were selected for amplification of DNA fragments in the C to D, F, G and I to J regions of the M. pneumoniae cytadhesin P1 genes. Amplified DNA fragments were visualized by staining with ethidium bromide after 2% agarose gel electrophoresis and by Southern hybridization with Alp-labeled probes. No amplification of the P1 genes was seen with any of five related Mycoplasma species, the others from M. pneumoniae. In all of 30 clinical isolates on PPLO medium, M. pneumoniae was detected with the F and G primer pairs, giving 100% of sensitivity. Of 69 throat swab specimens, 25 were positive with the F primer pairs, and 23 positive with the Gen Probe test. From these results, we conclude that the PCR with F or G primer pairs can be adapted as a practical method for the rapid diagnosis of M. pneumoniae infections.

Adhesins, Bacterial↗
PubMed1995

Endothelin-1-induced downregulation of ETB receptor mRNA: participation of cAMP.

In this study we examined the participation of cAMP formation in endothelin-1 (ET-1)-induced downregulation of ETB receptor mRNA in ROS 17/2 rat osteosarcoma cells. Dibutyryl cAMP induced downregulation of ETB receptor mRNA in a time-dependent manner. ET-1 induced production of inositol phosphates and an increase of cAMP level in ROS 17/2 cells. A stimulatory effect on cAMP level was also observed when A23187 plus PMA was added to the cells. The increase in cAMP level induced either by ET-1 or by A23187 plus PMA was inhibited by indomethacin. The downregulation of ETB receptor mRNA induced by ET-1 was significantly inhibited by indomethacin. These results suggest that the ET-1-induced downregulation of ETB receptor mRNA in ROS 17/2 cells may be partly mediated through the increase in cAMP level secondary to the activation of the phosphoinositide hydrolysis/Ca2+ transduction cascade.

Animals↗
PubMed1995

Altered production of endothelin-1 in the hypertrophied rat heart.

Although endothelin-1 (ET-1) has been shown to have potent hypertrophic effects in cultured cardiac myocytes, there is no evidence that the production of ET-1 is altered in the hypertrophied heart in vivo. We investigated mRNA and peptide levels of ET-1 in the rat heart hypertrophied due to pressure or volume overload. One week after surgery of abdominal aortic banding (AB) or aortic valve regurgitation (AR; the aortic valve was destroyed by a polyethylene catheter), the rats were sacrificed. Control sham-operated rats were also studied (AB-sham and AR-sham). The left ventricular (LV) weight to body weight ratio was significantly higher in AB rats than in AB-sham rats. It was also significantly higher in AR rats than in AR-sham rats. Therefore, AB rats and AR rats developed LV hypertrophy due to pressure and volume overload, respectively. The expression of ET-1 mRNA in the LV was markedly higher in AB rats than in AB-sham rats. The peptide level of ET-1 was also significantly higher in the LV of AB rats than in that of AB-sham rats. However, the expression of ET-1 mRNA in the LV of AR rats was similar to that of AR-sham rats. The present findings suggest that the production of ET-1 in the heart differs between pressure and volume overload-induced hypertrophy in rats.

Animals↗
PubMed1995

Effectiveness of preventive surgery for asymptomatic unruptured intracranial aneurysms.

Recently in Japan, physicians used MRI angiography (MRA) for the detection of asymptomatic intracranial diseases. Asymptomatic unruptured intracranial aneurysms (UIAs) are one of the most common abnormalities; usually the patients are advised to undergo preventive surgery. We evaluated the effectiveness of preventive surgery for asymptomatic UIAs, using published data in the literature with decision analysis on a Markov model. The baseline analysis showed that preventive surgery is superior to follow-up in a wide range of patient ages, but only by small QALY margin. Sensitivity analyses showed that the rate of rupture and the clinical outcome of surgery will influence the choice.

Adult↗
PubMed1995

Hypothalamic neurons are resistant to the intoxication with 3-nitropropionic acid that induces lesions in the striatum and hippocampus via the damage in the blood-brain barrier.

Modulation of the function of the blood-brain barrier (BBB) in the hypothalamus was investigated after the intoxication with 3-nitropropionic acid (3-NPA) that inhibits the succinate dehydrogenase. 3-NPA was administered to rats for three days. Following transcardial perfusion, brain sections were studied by immunohistochemistry. On the 2nd or 3rd day after 3-NPA, strong immunoreactions for blood-borne macromolecules, IgG, appeared in the striatum and hippocampus. Glial fibrillary acidic protein (GFAP) positive astroglias distributed heterogeneously, and induced nitric oxide synthase (iNOS) positive cells appeared around the vessels. A week later, bilateral lesions were detected in these areas. In the hypothalamus, there appeared a moderate immunoreaction for IgG, but no expression of iNOS. GFAP positive astroglias were rich especially around the vessels, and no loss in microtubule-associated protein 2 (MAP2) immunoreaction was detected, suggesting an intact BBB structure and no neuronal loss following 3-NPA intoxication. Data indicate that hypothalamic neurons are resistant to 3-NPA that induces specific lesions in the striatum and hippocampus via the damage in the BBB.

Animals↗
PubMed1995

[Decision making and informed consent in clinical medicine].

Information used in clinical medicine is always uncertain and every choice has risk of unfavorable outcome. The concept of informed consent includes full access and understanding of all relevant information by the patient with autonomic participation to the decision process. In this paper, possible cause of the lack of communication between physicians and patients is discussed along with the usefulness of decision science technology in clinical medicine.

Clinical Medicine↗
PubMed1995

Hand-arm vibration in tropical rain forestry workers.

Working conditions and health hazards including vibration syndrome related to forestry work using chain-saws were studied in Papua New Guinea and Indonesia. The subjects comprised 291 workers including 97 chain-saw operators. The health examination consisted of peripheral circulatory and sensory tests in the upper extremities. The vibration spectrum measured at the handle of the chain-saw indicated that these acceleration levels would lead to a moderately high risk of hand-arm vibration syndrome (HAVS). The peripheral circulatory function tests revealed dysfunction after more than five years vibration exposure. However, in general, the results of the function tests and subjective complaints showed fewer health problems compared to those of Japanese forestry workers. The reason of such differences of vibration effects seem to be the following: (1) warmer climate (more than 25 degrees C throughout the year), (2) young workers and short work experience. (3) short time vibration exposures on working days in the natural forests, (4) seasonal changes in logging work (5) healthy workers effects. Thus, we found no clear evidence that the workers of our study suffered from HAVS. A principal component analysis was applied. The factor score of the components of the reactive dynamics of peripheral circulation differed significantly after more than five years' exposure. On the other hand, we cannot deny the possibility that subclinical dysfunction of peripheral circulation may be caused by chain-saw operation in the tropics in future. Further investigations on the HAVS among forestry workers in the tropic environment are needed.

Adult↗
PubMed1994

Biochemical characterization and immunolocalization of SC2 protein: SC2 protein is indistinguishable from the cell adhesion molecule axonin-1.

SC2 is a monoclonal antibody that was previously shown to recognize a subset of neurons in the developing nervous system of the chick. We have now used the SC2 monoclonal antibody to purify from chick embryo brain membranes a glycoprotein that migrates at approximately 125 kDa on SDS/PAGE. The size of this protein and its distribution pattern in the spinal cord are similar to that observed for axonin-1. A polyclonal anti-axonin-1 antibody R26 specifically reacted with the SC2 protein from brain. This antibody, as well as polyclonal antibody (369) against purified SC2 protein, reacted with 115-130 kDa proteins in vitreous humor, a rich source of axonin-1, and with similar sized proteins precipitated from vitreous humor by the 369, and SC2 antibodies. Treatment of SC2 protein isolated from chick brain membranes with PI-PLC indicated that it contains a glycophosphatidylinositol (GPI) moiety. Co-aggregation experiments using Covaspheres with covalently bound proteins indicated that SC2 protein binds heterophilically to Ng-CAM. Immunohistochemical analysis of chick embryos showed that SC2 protein is abundant in the sensory nerve bundles of both the central and peripheral nervous systems during development. Its expression was restricted and it was specifically localized in the dorsal funiculus of the spinal cord, as well as in olfactory, retinal, trigeminal, vestibulocochlear, glossopharyngeal and vagal nerve fibers. The biochemical and immunohistochemical data show that SC2 protein is axonin-1, and the immunolocalization studies support the hypothesis that SC2 protein may play a role during development of particular fiber systems by interacting with other cell adhesion molecules such as Ng-CAM.

Animals↗
PubMed1994

Endothelin-1 activates mitogen-activated protein kinases through two independent signalling pathways in rat astrocytes.

Northern blot analysis and displacement study revealed that the endothelin (ET) receptor functionally expressed in rat primary cultured astrocytes is the ETB receptor. Mitogen-activated protein kinases (MAP kinases) in the cells were activated by 10 nM ET-1, a dose that maximally stimulated phosphoinositide hydrolysis. This activation was potently inhibited by pretreatment of the cells with phorbol 12-myristate 13-acetate (PMA) which leads to protein kinase C (PKC) down-regulation and was slightly inhibited by pretreatment with pertussis toxin (PTX). Pretreatment of the cells with PMA plus PTX completely inhibited the ET-1-augmented MAP kinase activity. Activation of MAP kinases was also induced by 0.1 nM ET-1, which hardly stimulated phosphoinositide hydrolysis. This activation was fully inhibited by pretreatment with PTX but insensitive to pretreatment with PMA. ET-1-stimulated production of inositol phosphates was not affected by pretreatment with PTX. These results suggest that activation of MAP kinases secondary to stimulation of the ETB receptor with ET-1 in rat primary cultured astrocytes was mediated through two independent signalling pathways. PKC-dependent pathway and PTX-sensitive G protein-mediated pathway.

Animals↗
PubMed1994

Electron-transfer from cytochrome c to ascorbate oxidase and its type 2 copper-depleted derivatives.

Rate constants have been determined for the electron-transfer reactions between reduced horse heart cytochrome c and resting cucumber ascorbate oxidase as functions of pH, ionic strength, and temperature. The second-order rate constant for the oxidation of reduced cytochrome c was determined to be k = 820 M-1 s-1 in 0.2 M phosphate buffer at pH 6.0 and 25 degrees C. The activation parameters were estimated to be delta H++ = 5 kJ mol-1 and delta S++ = -188 Jmol-1 K-1. The rate constants increased with decreasing buffer concentration, indicating that the electron-transfer from cytochrome c to ascorbate oxidase is realized by the local electrostatic interaction between them in spite of the reaction between positively charged proteins. Reactions of type 2 copper-depleted ascorbate oxidase whose type 3 coppers were in the reduced or oxidized form indicated that the type 1 copper site accepts an electron from cytochrome c. The reaction rate was remarkably increased with decreasing pH for both the native enzyme and derivatives. Further, on addition of hexametaphosphate anion the rate of the electron-transfer decreased because the association of both proteins to realize the electron-transfer was inhibited due to a change in distribution of the local charge on the protein surface(s).

Ascorbate Oxidase↗
PubMed1994

Molecular cloning of low-Ca(2+)-sensitive-type non-muscle alpha-actinin.

We previously reported the purification and characterization of a novel non-muscle alpha-actinin from chicken lung [Imamura, M. & Masaki, T, (1992) J. Biol. Chem. 267, 25927-25933]. The Ca2+ sensitivity of the lung alpha-actinin for the interaction with polymerized actin (F-actin) was much lower than those of the other reported non-muscle alpha-actinins. Here, we isolated a cDNA clone encoding the novel alpha-actinin by screening a chicken lung lambda g11 cDNA library with antibody specific for the low-Ca(2+)-sensitive alpha-actinin. The deduced amino acid sequence of the lung alpha-actinin showed 76%, 82% and 83% identity to those of chicken skeletal muscle, smooth-muscle and fibroblast-type alpha-actinin, respectively. Marked difference in the structure between the lung-type and the other alpha-actinins was found in the extreme NH2-terminal and in the COOH-terminal half; in the third and fourth regions of four spectrin-like repeats, and in two Ca(2+)-binding EF-hand consensus regions. The NH2-terminal-side EF-hand contained a notable defect in one of the five oxygen-containing amino acid side chains involved in chelating Ca2+, suggesting that the lower Ca2+ sensitivity of the lung alpha-actinin is ascribable to this defect. Northern blot analysis showed that the expression pattern of lung-type alpha-actinin mRNA in various non-muscle tissues differed from that of the other known non-muscle-type (fibroblast-type) alpha-actinin. The present results clearly demonstrate the existence of two structurally and functionally different types of non-muscle alpha-actinin; high-Ca(2+)-sensitive-type (NM1) and low-Ca(2+)-sensitive-type (NM2) alpha-actinin.

Actinin↗
PubMed1994

Activin A stimulates mitogenesis in Swiss 3T3 fibroblasts without activation of mitogen-activated protein kinases.

Activin A stimulated DNA synthesis and transient c-fos expression in quiescent Swiss 3T3 fibroblasts. The activin A-induced DNA synthesis was dose-dependent with a half-maximal effect obtained at 0.3 nM. The maximal response obtained at 10 nM was comparable with that induced by 5 ng/ml basic fibroblast growth factor. Swiss 3T3 fibroblasts expressed abundant high affinity binding sites for 125I-labeled activin A with a Kd value of 0.63 nM and the number of binding sites at 24,000/cell. Northern blot analysis revealed that Swiss 3T3 fibroblasts express a high level of type II activin receptor mRNA. In an attempt to elucidate the mechanism of mitogenic action of activin A, we examined the effect of activin A on mitogen-activated protein kinase activation. Unexpectedly, however, activin A did not induce kinase activation under conditions in which basic fibroblast growth factor and endothelin-1 at similar or even less potent mitogenic concentrations did. Furthermore, activin A did not induce phosphorylation of the Erk2 species of mitogen-activated protein kinase. These observations strongly suggest that the activation of mitogen-activated protein kinase is not a necessary step for activin A-induced DNA synthesis in Swiss 3T3 fibroblasts.

3T3 Cells↗