Search PubMed⌕ Search

Biomedical subjects

S Kawashima

Publications and source records attributed to S Kawashima.

At least 181 records · Page 10Linked to original sources
PubMed1996

Involvement of calpain in integrin-mediated signal transduction.

An antibody specific to the calpain cleavage site in talin, a cytoskeletal protein, was produced. This antibody selectively recognizes the C-terminal 200-kDa fragment generated when talin is digested by calpain and does not react at all with intact talin or the N-terminal 47-kDa fragment. To assess the involvement of calpain in the integrin-mediated signaling pathway, the effect of limited proteolysis of talin by calpain on platelet activation and aggregation was analyzed using this antibody. It was revealed that thrombin-stimulated platelet aggregation accompanies the autolytic activation of mu-calpain and the accumulation of the mu-calpain-generated 200-kDa fragment of talin. These changes were blocked by RGDS peptide which inhibits the binding of fibrinogen, an adhesive ligand, to the major integrin in platelets, alpha IIb beta 3, while RGES peptide, which has no fibrinogen-binding-inhibitory activity, had no effect. Membrane-permeable calpain inhibitors calpeptin and E-64d inhibited platelet aggregation, mu-calpain activation, and the limited proteolysis of talin. These results strongly suggest that calpain is involved in the integrin-mediated signal transduction pathway.

Amino Acid Sequence↗
PubMed1996

Expression of nitric oxide synthase in a murine model of viral myocarditis induced by coxsackievirus B3.

Nitric oxide is known to participate in the immune and inflammatory processes. In this study, we investigated the production of nitric oxide (NO) in murine viral myocarditis induced by coxsackievirus B3. The expression of inducible NO synthase (iNOS) mRNA in the heart first appeared on day 4 after virus inoculation and it was detectable for one month by reverse transcriptase-polymerase chain reaction (RT-PCR) methods. iNOS activity which was determined by the conversion of L-[3H]arginine to L-[3H]citrulline was increased on day 4 and revealed its peak on day 8. Immunohistochemistry on day 7 showed increased iNOS staining mainly in infiltrating macrophages and polymorphonuclear leukocytes. Thus, NO is thought to be produced in the heart and play an important role in a murine model of coxsackievirus B3-induced viral myocarditis.

Animals↗
PubMed1996

The origin of pattern reversal short latency visual evoked potential as determined by dynamic topography and the dipole tracing method.

The generator sites of the parietal P59 and occipital N26 components elicited by hemi-field pattern reversal stimuli were investigated. The topographic distribution of the occipital N26 component showed a paradoxical lateralization, whereas that of the parietal P59 component exhibited an anatomical lateralization. The equivalent dipoles of both occipital N26 and parietal P59 components were situated on the deep mesial surface of the functioning occipital lobe. The differences in these locations were not statistically significant, but the vector moment of the parietal P59 component projected toward the functioning parieto-occipital region and one of the occipital N26 components projected away from the functioning occipital region. The generator sites of the short latency component were considered to differ from those of the middle latency visual evoked potential. Therefore both the occipital pole and the deep cerebral structure, i.e., the lateral geniculate nucleus, may play a role in the generation of equivalent dipoles.

Brain↗
PubMed1996

Chronic effect of hyperprolactinemia on blood glucose and lipid levels in mice.

We studied the chronic effects of hyperprolactinemia, induced by ectopic pituitary grafting, on blood glucose and lipid levels in adult male mice. For one year after pituitary grafting, we measured the blood levels of prolactin, growth hormone (GH), insulin, glucose and free fatty acid (FFA) at various intervals. The graft caused consistent hyperprolactinemia without changes in the serum GH levels. Hypoglycemia developed at 1 and 3 months after grafting but was not accompanied by any changes of the serum insulin levels. Thereafter, the blood glucose and serum insulin levels began to increase in the pituitary-grafted (PG) mice, and at 12 months after the operation, both levels became significantly higher in PG mice than controls. The serum FFA levels and the weight of epididymal fat bodies were significantly lower in PG mice than controls from 3-12 months after the grafting. Thus, hyperprolactinemia leads to persistent hypolipidemia and biphasic changes in the blood glucose level.

Adipose Tissue↗
PubMed1996

Effects of chronic hypertension and left ventricular hypertrophy on the extent of infarct expansion in rats.

Left ventricular hypertrophy is an adaptive response to long standing hypertension. However, the influence of left ventricular hypertrophy with hypertension on extent of infarct expansion has not been studied. We compared the effects of left ventricular hypertrophy with hypertension on infarct expansion in spontaneously hypertensive rats (SHR, n = 76), Wistar-Kyoto rats (WKY; n = 46) and spontaneously hypertensive rats treated with delapril, an angiotensin converting enzyme (ACE) inhibitor (SHRD; n = 39). The survival rates at 7 days after myocardial infarction were 41%, 24%, and 46% for WKY, SHR, and SHRD. The survival rate of SHR was significantly lower than those of both SHRD and WKY (P < .05). In the surviving rats (18 SHR, 19 WKY, 18 SHRD), both left ventricular cavity area (LCVA) and the infarct segment length per the noninfarct segment length (FW/IVS), measured as indices of left ventricular dilation, were significantly less in SHR and SHRD than in WKY, and the thickness of the left ventricular free wall (Wth), used as an index of left ventricular thinning, was significantly higher in both SHR and SHRD than in WKY (P < .01). However, there was no significant difference in FW/IVS, LCVA, and Wth between SHR and SHRD. Hemodynamic findings 1 week after coronary occlusion demonstrated that all rats were in heart failure, and there were no significant differences in hemodynamics among the three groups. In conclusion, our findings showed that hypertrophy with hypertension reduced infarct expansion, but that reduction of blood pressure by ACE inhibitor did not reduce infarct expansion more than hypertrophy did. However, this finding suggest that an ACE inhibitor may improve the rate of survival of patients with left ventricular hypertrophy with hypertension.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

Regulation of nitric oxide synthase gene expression by cytokines.

Evidence is presented that not only macrophage type of NO synthase but also endothelial constitutive type of NO synthase genes are regulated by a variety of exogenous stimuli including cytokines. It is possible that pathophysiological concentrations of TNF-alpha noted in some patients with congestive heart failure may be sufficient to decrease levels for the constitutive form of NO synthase and increase those for the inducible form of NO synthase. Interestingly, chronic exercise in dogs was demonstrated to increases coronary vascular NO production and steady-state mRNA levels of ecNO synthase. Endogenous NO plays a crucial role in modulating vascular tone and inhibiting interactions of the vessel wall with circulating blood elements such as platelets, monocytes and neutrophils. It is possible that alterations in its synthesis or activity may play an important role in some cardiovascular disorders including congestive heart failure. Further studies of the pathophysiological significance of NO in specific experimental and clinical settings of congestive heart failure may provide a basis for improved therapeutic measures to enhance the synthesis or effect of endogenous NO, or to supplement its activity with exogenous NO donors or superoxide scavengers.

Animals↗
PubMed1996

Differential inhibition of calpain and proteasome activities by peptidyl aldehydes of di-leucine and tri-leucine.

To explore membrane-permeable synthetic inhibitors that discriminate between endogenous calpain and proteasome in cells, we examined the inhibition of profiles against calpain and proteasome in vitro and in vivo of peptidyl aldehydes possessing di-leucine and tri-leucine. The tripeptide aldehyde benzyloxycarbonyl-leucyl-leucinal (ZLLLal) strongly inhibited calpain and proteasome activities in vitro. The concentration required for 50% inhibition (IC50) of the casein-degrading activity of calpain was 1.25 microM, and the IC50s for the succinyl-leucyl-leucyl-valyl-tyrosine-4-methylcoumaryl-7-amide (Suc-LLVY-MCA)- and benzyloxycarbonyl-leucyl-leucyl-leucine-4-methylcoumaryl -7-amide (ZLLL-MCA)-degrading activities of proteasome were 850 and 100 nM, respectively. On the other hand, the synthetic dipeptide aldehyde benzyloxycarbonyl-leucyl-leucinal (ZLLal) strongly inhibited the casein degrading activity of calpain (IC50 1.20 microM), but the inhibition of proteasome was weak (IC50S for SucLLVY-MCA- and ZLLL-MCA-degrading activities were 120 and 110 microM, respectively). Thus, while calpain was inhibited by similar concentrations of ZLLal and ZLLLal, the inhibitory potencies of ZLLLal against the ZLLL-MCA- and Suc-LLVY-MCA-degrading activities in proteasome were 1,100 and 140 times stronger than those of ZLLal, respectively. To evaluate the effectiveness of these inhibitors on intracellular proteasome, the induction of neurite outgrowth in PC12 cells caused by proteasome inhibition was examined. ZLLLal and ZLLal initiated neurite outgrowth with optimal concentrations of 20 nM and 10 microM, respectively, again showing a big difference in the effective concentrations for the proteasome inhibition as in vitro. As for the effect on intracellular calpain, the concentration of ZLLLal and ZLLal required for the inhibition of the autolytic activation of calpain in rabbit erythrocytes were 100 and 100 microM or more, respectively. The almost equal inhibitory potencies of ZLLLal and ZLLal were in agreement with the inhibition of calpain in vitro. These differential effects of inhibitors against calpain and proteasome are potentially useful for identifying the functions of calpain and proteasome in cell physiology and pathology.

Animals↗
PubMed1996

Identification of a novel growth-promoting factor with a wide target cell spectrum from various tumor cells as catalase.

We have previously reported the purification from human erythrocyte extracts of a novel growth-promoting factor with a wide target cell spectrum. The factor has been identified as catalase. As cell extracts from a variety of tumor cell types exhibited both growth-promoting and catalase activities, the relationship between the two activities was examined using cell extracts from three different cell types, human myeloid cells (U937), human melanoma cells (A375-C6), and human B cells (Daudi). The growth-promoting and catalase activities were well correlated in these cell extracts. The antibody against human catalase absorbed not only catalase activity, but also the growth-promoting activity of extracts from these cell types. Treatment of the cell extracts from these cells with an irreversible catalase inhibitor, aminotriazole, abolished both the catalase and growth-promoting activities. In contrast, glutathione peroxidase (GSH-Px) activity was neither absorbed with the anti-catalase antibody, nor inhibited by aminotriazole. In addition, GSH-Px exhibited growth-promoting activity only in the presence of glutathione (GSH). These results, in conjunction with the effect of aminotriazole on the growth-promoting activity of catalase, suggest that catalase is the major growth-promoting molecule in the cell extracts, and H2O2-decomposing activity is important. Northern blot analysis revealed that these cells contained authentic catalase mRNA, and the mRNA level was compatible with the catalase and growth-promoting activities in the cell extracts. These results suggest that the growth-promoting activity in the tumor cell extracts is due to catalase.

Amitrole↗
PubMed1996

Deep negative T waves and abnormal cardiac sympathetic image (123I-MIBG) after the Great Hanshin Earthquake of 1995.

The authors report the increased incidence of patients with deep negative T waves without Q wave after the Great Hanshin Earthquake of 1995. Subjects underwent cardiac metaiodobenzyl guanidine (123I-MIBG) imaging, 201Tl scintigraphy, and coronary angiography. Among 2,756 inpatients of the preceding 5-year period, 33 (1.2%) showed the deep negative T waves, whereas 6 of 94 (6.4%; P < 0.001) showed it after the earthquake. Four of six patients had an episode of chest pain. Cardiac metaiodobenzyl guanidine imaging revealed the extent defects in all six patients despite a minimal change of 201Tl image. In addition, cardiac metaiodobenzyl guanidine imaging washout rate was hastened not only in the defect area but also in the nondefect area, which suggested augmented sympathetic activation. Natural disasters can affect the frequency of deep negative T waves, which relate abnormal cardiac sympathetic imaging.

3-Iodobenzylguanidine↗
PubMed1996

Transient brain ischaemia provokes Ca2+, PIP2 and calpain responses prior to delayed neuronal death in monkeys.

To clarify the mechanism of postischaemic delayed cornu Ammonis (CA)-1 neuronal death, we studied correlations among calpain activation and its subcellular localization, the immunoreactivity of phosphatidylinositol 4,5-bisphosphate (PIP2) and Ca2+ mobilization in the monkey hippocampus by two independent experimental approaches: in vivo transient brain ischaemia and in vitro hypoxia-hypoglycaemia of hippocampal acute slices. The CA-1 sector undergoing 20 min of ischaemia in vivo showed microscopically a small number of neuronal deaths on day 1 and almost global neuronal loss on day 5 after ischaemia. Immediately after ischaemia, CA-1 neurons ultrastructurally showed vacuolation and/or disruption of the lysosomes. Western blotting using antibodies against inactivated or activated mu-calpain demonstrated mu-calpain activation specifically in the CA-1 sector immediately after ischaemia. This finding was confirmed in the perikarya of CA-1 neurons by immunohistochemistry. CA-1 neurons on day 1 showed sustained activation of mu-calpain, and increased immunostaining for inactivated and activated forms of mu- and m-calpains and for PIP2. Activated mu-calpain and PIP2 were found to be localized at the vacuolated lysosomal membrane or endoplasmic reticulum and mitochondrial membrane respectively, by immunoelectron microscopy. Calcium imaging data using hippocampal acute slices showed that hypoxia-hypoglycaemia in vitro provoked intense Ca2+ mobilization with increased PIP2 immunostaining specifically in CA-1 neurons. These data suggest that transient brain ischaemia increases intracellular Ca2+ and PIP2 breakdown, which will activate calpain proteolytic activity. Therefore, we suggest that activated calpain at the lysosomal membrane, with the possible release of biodegrading enzyme, will cause postischaemic CA-1 neuronal death.

Animals↗
PubMed1996

Expression of dopamine transporter at the tips of growing neurites of PC12 cells.

The four kinds of oligopeptides specific in amino acid sequence to a rat dopamine transporter (DAT), peptide-1-peptide-4, were chemically synthethized. An attempt to produce antipeptide antibodies against these oligopeptides was made with an in vitro immunization method. Two monoclonal antibodies, MAbs H-1a and H-1b, were produced against one of the oligopeptides, peptide-1. Western blot analysis confirmed that the two antibodies recognized an approximately 85,000 Da protein in a synaptosomal fraction prepared from the rat striatum but none in the fraction from the cerebellum. The specificity of the antibody to DAT was also confirmed by an antibody absorption test using two synthetic oligopeptides, one of which is specific only to DAT. These results have confirmed the specificity of the present antibody to DAT. The expression and subcellular localization of DAT were immunohistochemically examined with MAbs H-1a and H-1b in PC12 cells treated with nerve growth factor (NGF). The antibody labeled the surface of PC12 cells. When the cells were treated with NGF, the expression of DAT was significantly emphasized, first in the area mainly including the Golgi apparatus and rough endoplasmic reticulum and then on the surface of growth cones from the beginning of neurite outgrowth. DAT was detected by Western blot analysis in a microsomal fraction prepared from PC12 cells. The activity of DAT in the PC12 cells was pharmacologically confirmed by the uptake of [3H]-dopamine and blockade by uptake inhibitors. The NGF treatment doubled the dopamine uptake activity. GBR12909, a specific inhibitor of DAT, blocked the [3H]-dopamine at a concentration of 10(-7) M. The expression of DAT and norepinephrine transporter (NET) mRNA in the PC12 cells was examined by reverse transcriptase-polymerase chain reaction (RT-PCR). DAT mRNA significantly increased in the NGF-treated cells after 7 days of incubation, whereas NET mRNA markedly decreased.

Amino Acid Sequence↗
PubMed1996

Endothelial constitutive nitric oxide synthase protein and mRNA increased in rabbit atherosclerotic aorta despite impaired endothelium-dependent vascular relaxation.

Atherosclerotic arteries are well known to exhibit impaired endothelium-dependent relaxation (EDR), but the exact mechanism of this impairment remains unclear. Recently, endothelial constitutive nitric oxide synthase (ECNOS), which generates nitric oxide and mediates EDR, was cloned, and ECNOS mRNA expression was reported to be modified by various cytokines, lipoproteins, and shear stress. To investigate the expression of ECNOS mRNA and protein in atherosclerotic arteries with impaired EDR, thoracic aortas isolated from Watanabe heritable hyperlipidemic (WHHL) rabbits were examined by using in situ hybridization and immunohistochemistry. Compared with thoracic aortas from Japanese White rabbits, WHHL aortas exhibited significantly impaired EDRs, although both in situ hybridization and immunohistochemistry exhibited enhanced expression of ECNOS mRNA and protein in WHHL aortas. There was no significant relationship between expression of ECNOS mRNA and protein of endothelial cells and age of the examined WHHL aortas. These data suggest that the mechanism of impaired EDR in atherosclerotic arteries is not due to the decrease in ECNOS mRNA and protein.

Acetylcholine↗
PubMed1996

[Pollen information of airborne Japanese cedar pollen using a simulation method].

We have developed a simulation method of airborne Cryptomeria japonica pollen distribution on a map displayed visually on a TV screen. Each patient can be available the information where the place he or she lives. The pollen season in 1995, we served the information about airborne pollen distribution on a map and C. japonica flowering areas on a map to a local resident through TV broadcasting. To verify the simulation method, comparison was made between the result from actual pollen counting and from simulation. It was clarified that both results were comparatively agreed on daily basis. Problem about compatibility among personal computers were solved to rewrite the program of displaying the image using Visual Basic for MS-Windows and create image files. The files can be read continuously by animation software. We think the information can be offered to local resident, local clinicians and patients waiting at the clinics by use of computer networks.

Computer Communication Networks↗
PubMed1996

[Effects of global climate change on Japanese cedar pollen concentration in air--estimated results obtained from Yamagata City and its surrounding area].

The effects of global warming on Japanese cedar pollen concentration in air were examined. There was a significant increase in total pollen count in years where small or average values of pollen dispersion were observed and where summertime temperatures were postulated to have risen from 2 to 5 degrees C. There were no remarkable differences in total pollen count in years where large values of pollen dispersion were observed. On the other hand, a drastic decrease in total pollen count was expected when summertime temperatures were postulated to have dropped from 2 to 5 degrees C. A major factor controlled the value of total pollen count was examined by use of a simulation method of airborne Cryptomeria japonica pollen. The values of total pollen count mainly controlled by the amount of male flower at basins and in Japanese cedar forested areas, and the manner in which plains isolated from pollen sources are considered in part to be subjected to meteorological conditions. The difference of initiation time of the pollen season has no great influence on the values of total pollen count.

Air Pollution↗
PubMed1995

N23K, a gene transiently up-regulated during neural differentiation, encodes a precursor protein for a newly identified neuropeptide nociceptin.

We used a subtraction cloning approach to isolate a cDNA of N23K, whose mRNA and protein are transiently up-regulated in mouse NS20Y cells undergoing neurite outgrowth induced by treatment of dibutyryl cyclic AMP. N23K encodes a precursor protein for a newly discovered rat neuropeptide nociceptin. As with other neuropeptide precursors, the N23K protein contains a putative signal peptide rich in hydrophobic amino acids at the N-terminus. N23K mRNA is present only in brain and spinal cord in adult mouse, and is expressed at higher levels in early postnatal brain. These findings suggest that the N23K protein functions not only as a neuropeptide precursor but also as an important component in neuronal differentiation.

Amino Acid Sequence↗
PubMed1995

Elevated calcium level induces calcium-dependent proteolysis of A-CAM (N-cadherin) in heart--analysis by detergent-treated model.

Calcium overload induces cardiac muscle cell dysfunction in cardiovascular diseases. We investigated the effects of elevated calcium level on adherens-junction-specific cell adhesion molecule (A-CAM). Incubation of Triton X-100-treated canine heart homogenate in the presence of Ca2+ reduced the content of A-CAM. Reduction in A-CAM requires milli-molar Ca2+ and was inhibited by protease inhibitors, leupeptin and calpeptin. Immunohistochemical observation revealed that m-calcium-activated neutral protease (m-CANP) was colocalized with A-CAM in intercalated disks. These data suggested that m-CANP proteolyzes A-CAM in response to calcium overload in cardiac muscle.

Animals↗