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Biomedical subjects

J Harada

Publications and source records attributed to J Harada.

At least 37 records · Page 2Linked to original sources
PubMed1999

Activation of caspase-3 in beta-amyloid-induced apoptosis of cultured rat cortical neurons.

Amyloid beta protein (Abeta) has been thought to participate in the neurodegeneration associated with Alzheimer's disease. We here report on caspase-3 activation by Abeta-treatment of cultured neurons. Treatment of rat primary cortical culture with Abeta 25-35, an active fragment of Abeta, induced neuronal death as determined by a decrease in neuron-specific microtubule-associated protein 2 (MAP2)-like immunoreactivity and by the release of cellular lactate dehydrogenase (LDH). Abeta 25-35 also induced elevation of caspase-3-like Ac-DEVD-MCA cleavage activity in advance of neuronal death with similar concentration-dependency for neuronal death. Inhibitor sensitivity of the Abeta-induced proteolytic activity was similar to that of human recombinant caspase-3. Cleavage of pro-caspase-3 and cleavage of its endogenous substrates, poly (ADP-ribose) polymerase (PARP) and alpha-fodrin, were produced by Abeta-treatment. A caspase-3 inhibitor, Ac-DEVD-CHO, prevented Abeta-induced DNA fragmentation and cleavage of alpha-fodrin, but not of PARP. Caspase inhibitor of broad specificity, Z-VAD-CH(2)-DCB, additionally prevented Abeta-induced cleavage of PARP and some early loss of cell membrane integrity measured by LDH release. However, Abeta-induced condensation of nuclear chromatin and most of the late disintegration of cell membranes were not prevented in the presence of these caspase inhibitors. These results suggest that activation of both caspase-3 and caspase(s) other than caspase-3 play distinct roles in Abeta-induced apoptosis of rat cortical neurons. Furthermore, in the presence of caspase inhibitors, Abeta-induced neuronal death still occurred with different morphological features.

Amyloid beta-Peptides↗
PubMed1999

Expression of the 180-kD ribosome receptor induces membrane proliferation and increased secretory activity in yeast.

Expression of the canine 180-kD ribosome receptor (p180) in yeast cells resulted in a marked proliferation of intracellular membranes. The type of membranes observed varied with the expression of specific portions of p180. Rough membranes predominated when the ribosome binding domain of p180 was present, whereas expression constructs lacking this region resulted in smooth membranes. Northern analysis indicated that expression of the NH(2)-terminal 767 amino acids (DeltaCT), which include the ribosome binding domain, upregulated the transcription and translation of genes involved in exocytosis. The membranes that were proliferated were functional as these cells overcame a temperature-sensitive translocation defect. Most significantly, cells that overexpressed DeltaCT and proliferated rough endoplasmic reticulum exhibited severalfold higher levels of secretion of an ectopically expressed secretory protein. We conclude that p180 expression triggers a cascade of events leading to an increase in secretory potential akin to the terminal differentiation of mammalian secretory cells and tissues.

Animals↗
PubMed1999

ATF-2 is a common nuclear target of Smad and TAK1 pathways in transforming growth factor-beta signaling.

Upon transforming growth factor-beta (TGF-beta) binding to its cognate receptor, Smad3 and Smad4 form heterodimers and transduce the TGF-beta signal to the nucleus. In addition to the Smad pathway, another pathway involving a member of the mitogen-activated protein kinase kinase kinase family of kinases, TGF-beta-activated kinase-1 (TAK1), is required for TGF-beta signaling. However, it is unknown how these pathways function together to synergistically amplify TGF-beta signaling. Here we report that the transcription factor ATF-2 (also called CRE-BP1) is bound by a hetero-oligomer of Smad3 and Smad4 upon TGF-beta stimulation. ATF-2 is one member of the ATF/CREB family that binds to the cAMP response element, and its activity is enhanced after phosphorylation by stress-activated protein kinases such as c-Jun N-terminal kinase and p38. The binding between ATF-2 and Smad3/4 is mediated via the MH1 region of the Smad proteins and the basic leucine zipper region of ATF-2. TGF-beta signaling also induces the phosphorylation of ATF-2 via TAK1 and p38. Both of these actions are shown to be responsible for the synergistic stimulation of ATF-2 trans-activating capacity. These results indicate that ATF-2 plays a central role in TGF-beta signaling by acting as a common nuclear target of both Smad and TAK1 pathways.

Activating Transcription Factor 2↗
PubMed1999

Methicillin-resistant Staphylococcus aureus infections after scleral buckling procedures for retinal detachments associated with atopic dermatitis.

OBJECTIVE: To determine the incidence and the clinical course of methicillin-resistant Staphylococcus aureus as a cause of acute-onset infections in patients with atopic dermatitis after a scleral buckling procedures. DESIGN: A retrospective chart review. PARTICIPANTS: Two hundred eighty-seven patients (293 eyes) who underwent scleral buckling procedures to treat rhegmatogenous retinal detachments at either Osaka Rosai Hospital or Osaka University Medical School between July 1, 1995, and June 30, 1997, participated. Of these, 32 eyes (10.9%) were associated with atopic dermatitis. INTERVENTION: Demographic and clinical data were abstracted from patients' medical records. MAIN OUTCOME MEASURES: The incidence, clinical features, and management of postoperative infections associated with methicillin-resistant S. aureus were studied. RESULTS: Methicillin-resistant S. aureus infection after scleral buckling procedures was identified in 6 (18.8%) of 32 eyes of patients with atopic dermatitis but in only 1 (0.4%) of the other 261 cases without atopic dermatitis (P < 0.001). The average interval from the scleral buckling procedures to the initial onset of infection was 8.3 +/- 9.1 days (range, 2-28 days). Bacterial infection and inflammation were controlled in four eyes by prompt removal of the infected buckle in combination with vancomycin administration. In the other three eyes, however, repeat intravitreous injections of vancomycin or emergent vitrectomies were required because of the development of endophthalmitis. CONCLUSIONS: Methicillin-resistant S. aureus is an important causative pathogen of scleral buckling infections, particularly in patients with retinal detachment associated with atopic dermatitis. Preoperative evaluation and intraoperative attention to contamination are recommended to prevent methicillin-resistant S. aureus infections in these patients.

Acute Disease↗
PubMed1999

An inhibitor of p38 and JNK MAP kinases prevents activation of caspase and apoptosis of cultured cerebellar granule neurons.

Both p38 mitogen-activated protein kinase (p38) and c-Jun N-terminal kinase (JNK) are known to play important roles in neuronal apoptosis. However, the relationship between these kinases and caspases, another key mediator of apoptosis, is unclear. In the present study, we investigated the possible effects of SB203580 [(4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-i mid azole], an inhibitor of p38, on caspase activation and apoptosis of cultured rat cerebellar granule neurons. In granule neurons, SB203580 prevented apoptosis that was induced by lowering the concentration of KCl in the culture medium for 24 hr. SB203580 also prevented augmentation of caspase-3-like protease activity at 8 hr after the low KCl treatment. The IC50 values of SB203580 for both events were between 3 microM and 10 microM. Expression and phosphorylation of c-Jun, potently induced by low KCl treatment, were prevented by SB203580 at 10 microM. Z-Asp-CH2-DCB, a caspase inhibitor with anti-apoptotic activity, did not inhibit the induction and phosphorylation of c-Jun. Granule neurons displayed high levels of p38 and JNK activities. SB203580 inhibited not only p38 but also JNK activities extracted from granule neurons. These results suggest that activation of c-Jun by p38 and/or JNK mediates the activation of caspase in the low KCl-induced apoptosis in cerebellar granule neurons.

Animals↗
PubMed1999

[MR temperature monitoring by the proton phase shift (PPS) method with a 0.3T open-type MR scanner: experimental study].

Several MR parameters are sensitive to temperature change, notably, T1 relaxation time, proton phase shift (PPS) and diffusion coefficient. The PPS method has been considered for temperature monitoring during laser ablation owing to its tissue-independence and its ability to be used with a mid-magnetic field. Using the PPS method, we experimentally evaluated MR temperature monitoring with a 0.3T open-type MR scanner. Temperature change was reproducibly described as color mapping image. The PPS method was suitable for MR temperature monitoring in interventional MRI.

Magnetic Resonance Imaging↗
PubMed1998

Inhibitors of interleukin-1 beta-converting enzyme-family proteases (caspases) prevent apoptosis without affecting decreased cellular ability to reduce 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide in cerebellar granule neurons.

We assessed the possible role of interleukin-1beta-converting enzyme-family proteases (caspases) in apoptosis in cultured rat cerebellar granule neurons. CPP32 (caspase-3)-like protease activity was augmented by low KCl treatment, preceding neuronal cell death. Agents such as brain-derived neurotrophic factor (BDNF), dibutylyl cAMP, NMDA, actinomycin D, S-adenosyl-L-methionine, and spermine prevented apoptosis. For various neuroprotective agents, the degree of apoptosis prevention correlated with the prevention of the activation of CPP32-like protease. Furthermore, Z-Asp-2, 6-dichlorobenzoyloxy-methylketone (Z-Asp-CH2-DCB), Boc-Asp-fluoromethylketone (Boc-Asp-FMK), and Z-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK), which are inhibitors of caspases, also prevented apoptosis. In contrast to many other neuroprotective agents, these inhibitors of caspases showed little effect on the decrease of cellular 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) reduction activity after low KCl treatment. The neurons rescued by these inhibitors of caspases during low KCl treatment were in a hypoenergic state in their ATP levels and vulnerable to subsequent treatment with medium containing high KCl or glutamate which induce an influx of Ca2+, but which are less toxic to normal neurons. These results suggest that caspase(s) are involved in the apoptosis of cerebellar granule neurons and that several agents protect neurons from death by blocking the activation of the protease(s). Although several caspase inhibitors examined in this study protect neurons from apoptosis, rescued neurons are vulnerable to subsequent stimuli that induce necrotic cell death.

Animals↗
PubMed1997

Polyamines prevent apoptotic cell death in cultured cerebellar granule neurons.

Polyamines play critical roles during the development of brain neurons. In the present study we examined the effects of polyamines on neuronal apoptotic death. Rat cerebellar granule neurons were cultured in the presence of a depolarizing concentration of KCl (25 mM) in the medium. Apoptotic neuronal death was induced by changing the medium to that containing 5.6 mM KCl without serum. Spermine as well as spermidine and putrescine prevented cell death in a concentration-dependent manner with the order of potency being spermine > spermidine > putrescine. The effect of spermine was partially blocked by several NMDA-type glutamate receptor antagonists including (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801). MK-801-sensitive neuroprotection by spermine depended on cell density. Activation of CPP32 (caspase-3/Yama/apopain)-like proteolytic activity, a key mediator of apoptosis, precedes neuronal death, and polyamines prevented an increase in this activity. These results demonstrate that polyamines protect neurons from apoptotic cell death through both NMDA receptor-dependent and -independent mechanisms, acting upstream from the activation of CPP32-like protease(s).

Animals↗
PubMed1997

[Principle and clinical application of MRI].

Magnetic resonance imaging(MRI) is widely used for whole body diagnosis. Spin echo and gradient echo are principle pulse sequences for MRI. Fast scan imaging is now available and can obtained excellent imaging quality with reduced scan time. Using a fast scan pulse sequence, dynamic study, functional and perfusion imaging can be performed in routine clinical practices. Biopsy and thermal therapy of brain and other parts of body are now being performed under MR monitoring and control.

Humans↗
PubMed1996

Tumor necrosis factor receptor-associated factor (TRAF)-1, TRAF-2, and TRAF-3 interact in vivo with the CD30 cytoplasmic domain; TRAF-2 mediates CD30-induced nuclear factor kappa B activation.

CD30 is a member of the tumor necrosis factor receptor superfamily, which can transduce signals for proliferation, death, or nuclear factor kappa B (NF-kappa B) activation. Investigation of CD30 signaling pathways using a yeast two-hybrid interaction system trapped a cDNA encoding the tumor necrosis factor receptor-associated factor (TRAF)-2 TRAF homology domain. TRAF-1 and TRAF-3 also interacted with CD30, and > 90% of in vitro-translated TRAF-1 or -2, or 50% of TRAF-3, bound to the CD30 cytoplasmic domain. TRAF-1, -2, and -3 bound mostly, but not exclusively, to the carboxyl-terminal 36 residues of CD30. The binding was strongly inhibited by a CD30 oligopeptide centered around a PXQXT (where X is any amino acid) motif shared with CD40 and the Epstein-Barr virus transforming protein LMP1, indicating that this motif in CD30 is an important determinant of TRAF-1, -2 or -3 interaction. At least 15% of TRAF-1, -2, or -3 associated with CD30 when coexpressed in 293 cells. The association was not affected by CD30 cross-linking. However, cross-linking of CD30 activated NF-kappa B. NF-kappa B activation was dependent on the carboxyl-terminal 36 amino acids of CD30 that mediate TRAF association. TRAF-2 has been previously shown to have a unique role in TRAF-mediated NF-kappa B activation, and NF-kappa B activation following CD30 cross-linking was blocked by a dominant negative TRAF-2 mutant. These data indicate that CD30 cross-linking-induced NF-kappa B activation is predominantly TRAF-2-mediated.

Amino Acid Sequence↗
PubMed1996

High-performance liquid chromatographic separation of ultraviolet-absorbing bile alcohol derivatives.

This paper describes the high-performance liquid chromatographic separation of UV-absorbing bile alcohol derivatives. Bile alcohols were treated with 3 alpha-hydroxysteroid dehydrogenase to form the corresponding 3-keto bile alcohols. The 3-keto bile alcohols produced were converted to the 2,4-dinitrophenylhydrazone derivatives, separated using a Nova-Pak Phenyl column, and monitored at 364 nm. The separation of stereoisomers related to the configuration of hydroxyl groups on the side chain of the bile alcohols, which was not achieved by gas chromatography, could also be accomplished.

Animals↗
PubMed1996

The effect of succinylcholine on energy metabolism studied by 31P-NMR spectroscopy in rat denervated skeletal muscle.

BACKGROUND: The goals of this study were: (1) to demonstrate the differences of metabolic changes induced by succinylcholine (SCh) administration between normal and denervated muscle by 31P-NMR spectroscopy: (2) to determine whether three kinds of drugs (vecuronium, midazolam and magnesium sulfate) could prevent these metabolic changes. METHODS: Following unilateral sciatic nerve section, 20 male Wistar rats were studied at three-week intervals. After SCh 1 mg.kg-1 was administered intravenously, the changes of the inorganic phosphate/phosphocreatine (Pi/PCr) ratio, the beta ATP/(PCr+Pi) ratio, and intracellular pH were measured by 31P-NMR both in normal and denervated hind limb muscles of 5 rats. The other 15 rats were allocated to the pretreatment groups by the following drugs: vecuronium 0.02 mg.kg-1, midazolam 0.1 mg.kg-1 and magnesium sulfate 60 mg.kg-1. After pretreatment 3 min before SCh administration, we measured the same parameters by 31P-NMR. RESULTS: SCh administration did not change the Pi/PCr ratio in normal muscle, but significantly increased that in denervated muscle (P < 0.05). This increase of the Pi/PCr ratio was also observed in all pretreated groups but was minimal as compared with that in non-pretreatment denervated muscle. CONCLUSION: These data suggested that SCh administration decreased the level of "energy reserve" in denervated muscle, and that this metabolic change was not totally inhibited by vecuronium, midazolam, or magnesium sulfate.

Adenosine Triphosphate↗
PubMed1996

[Evaluation of the training of the anesthesiologist].

In order to evaluate both the knowledge and the degree of competence acquired by anesthesiology trainees, we constructed a checklist and began using it in January 1994. Twenty-one trainees participated in a 3-month program ending in February 1995. By means of the checklist, we attempted to evaluate the extent of their individual attainment. The total number of anesthesia administered was 50.9 +/- 7.8 cases. The total anesthesia time was 212.0 +/- 32.8 hours, and 76.2 % of the anesthesia methods applied involved either nitrous oxide-sevoflurane or nitrous oxide-isoflurane. Using a 5-level rating scale, the self-assessment by the supervising doctor tended to be one point higher than the assessment by the trainees. We plan to improve this checklist to improve the results of training.

Anesthesia, Inhalation↗
PubMed1995

Solid Tubular Carcinoma of the Breast: MR Imaging and Pathologic Correlation.

PURPOSE: Solid tubular carcinoma of the breast is a recognizable histologic type of invasive ductal carcinoma, characterized by rare axillary lymph nodal metastases and a good prognosis. The purpose of this study is to describe the magnetic resonance (MR) characteristics of solid tubular carcinoma and to emphasize the spotty appearance on the MR subtraction images. MATERIALS AND METHODS: We reviewed the MR findings of seven patients with biopsy-proven solid tubular carcinoma. Two of the 7 cases were of the pure type (more than 85% solid tubular component) and the remaining 5 were of the mixed type (50% to 85% solid tubular component). The mean age of the patients was 56 years. RESULTS: The mean size of the lesions was 28 mm. On T1-weighted images four of the lesions were visible and three were not identified. After Gd-DTPA all the lesions were enhanced. On the subtraction images, g" popcorn" appearence areas were noted in the stained mass. CONCLUSION: Our preliminary results suggest that solid tubular carcinomas have a characteristic apperarence on the subtraction MR images.

Journal Article↗
PubMed1995

The characteristics of laser-Doppler flowmetry for the measurement of regional cerebral blood flow.

The fundamental characteristics of laser-Doppler flowmetry (LDF), especially the depth of cerebral blood flow (CBF) measurement, have not been widely studied in the brain tissue; however, LDF has been widely used in recent clinical and experimental studies. We investigated the depth of CBF measurement and other characteristics related to the use of LDF in the brain. In an animal experimental study, the distribution of laser light and the depth of CBF measurement of LDF were measured by using modified LDF probes. CBF in various conditions was also measured by the LDF and hydrogen clearance method. Laser light of low output lost directivity and was dispersed into a hemispherical form in the brain tissue. The depth of CBF measurement was approximately 100 to 400 microns, depending on the intensity of the emitted laser light, and was affected by changes of CBF. In the physiological condition, the close correlation between the values of CBF by the LDF and hydrogen clearance method was obtained. After cardiac arrest, the CBF value of LDF did not immediately show a 0 value. LDF has several special characteristics, and the sample volume was very small. It is important to pay attention to the several special characteristics of LDF.

Animals↗