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Biomedical subjects

K Toyooka

Publications and source records attributed to K Toyooka.

At least 19 recordsLinked to original sources
PubMed2006

The characteristics and measuring technique of refractory dissolved organic substances in urban runoff.

It is considered that refractory dissolved organic substances have caused an increase in the COD concentration in Lake Biwa in recent years. We investigated the organic matter in the first flush of stormwater runoff from a road in the watershed area of the lake, and studied the possibility of improvement in the water environment from that aspect. After percolating the stormwater through soil, we analyzed organic substances fractionated by using GPC-TC. And we examined the effect of removal of organic substances by comparing the peak height before and after percolation. In the result of the experiments, we found that soil infiltration reduced the refractory dissolved organic substance and we successfully designed a system for a simple and easy experimental facility to treat urban runoff.

Biodegradation, Environmental↗
PubMed2002

Abnormal expression of epidermal growth factor and its receptor in the forebrain and serum of schizophrenic patients.

Epidermal growth factor (EGF) comprises a structurally related family of proteins containing heparin-binding EGF-like growth factor (HB-EGF) and transforming growth factor alpha (TGFalpha) that regulates the development of dopaminergic neurons as well as monoamine metabolism. We assessed the contribution of EGF to schizophrenia by measuring EGF family protein levels in postmortem brains and in fresh serum of schizophrenic patients and control subjects. EGF protein levels were decreased in the prefrontal cortex and striatum of schizophrenic patients, whereas the levels of HB-EGF and TGFalpha were not significantly different in any of the regions examined. Conversely, EGF receptor expression was elevated in the prefrontal cortex. Serum EGF levels were markedly reduced in schizophrenic patients, even in young, drug-free patients. Chronic treatment of animals with the antipsychotic drug haloperidol had no influence on EGF levels in the brain or serum. These findings suggest that there is abnormal EGF production in various central and peripheral tissues of patients with both acute and chronic schizophrenia. EGF might thus provide a molecular substrate for the pathologic manifestation of the illness, although additional studies are required to determine a potential link between impaired EGF signaling and the pathology/etiology of schizophrenia.

Adult↗
PubMed2002

Gene expression profiles in the brain from phencyclidine-treated mouse by using DNA microarray.

Recently DNA microarray technology has been introduced into analyses of comprehensive biological functions. This DNA microarray is a new technology for simultaneous analysis to examine expression patterns of thousands of genes. It was thought that this technique should be very useful for examination of cellular and molecular mechanisms of drugs of abuse: cocaine, amphetamine, and others. This technology was therefore applied for the rapid analysis of gene expression in the brain from phencyclidine-treated mice. Mainly mouse DNA microarray was examined by using labeled cDNAs produced from a control mouse brain mRNA and from brain mRNA of mouse exposed to drugs as probes. Some changes in a probe from brain mRNA of drug-treated mouse could be observed, but it was necessary to examine another DNA microarray, including more samples from the brain.

Animals↗
PubMed2001

Cotyledon cells of Vigna mungo seedlings use at least two distinct autophagic machineries for degradation of starch granules and cellular components.

alpha-Amylase is expressed in cotyledons of germinated Vigna mungo seeds and is responsible for the degradation of starch that is stored in the starch granule (SG). Immunocytochemical analysis of the cotyledon cells with anti-alpha-amylase antibody showed that alpha-amylase is transported to protein storage vacuole (PSV) and lytic vacuole (LV), which is converted from PSV by hydrolysis of storage proteins. To observe the insertion/degradation processes of SG into/in the inside of vacuoles, ultrastructural analyses of the cotyledon cells were conducted. The results revealed that SG is inserted into LV through autophagic function of LV and subsequently degraded by vacuolar alpha-amylase. The autophagy for SG was structurally similar to micropexophagy detected in yeast cells. In addition to the autophagic process for SG, autophagosome-mediated autophagy for cytoplasm and mitochondria was detected in the cotyledon cells. When the embryo axes were removed from seeds and the detached cotyledons were incubated, the autophagosome-mediated autophagy was observed, but the autophagic process for the degradation of SG was not detected, suggesting that these two autophagic processes were mediated by different cellular mechanisms. The two distinct autophagic processes were thought to be involved in the breakdown of SG and cell components in the cells of germinated cotyledon.

Autophagy↗
PubMed2001

Identification of a membrane-associated cysteine protease with possible dual roles in the endoplasmic reticulum and protein storage vacuole.

SH-EP is a vacuolar cysteine proteinase from germinated seeds of Vigna mungo. The enzyme has a C-terminal propeptide of 1 kDa that contains an endoplasmic reticulum (ER) retention signal, KDEL. The KDEL-tail has been suggested to function to store SH-EP as a transient zymogen in the lumen of the ER, and the C-terminal propeptide was thought to be removed within the ER or immediately after exit from the ER. In the present study, a protease that may be involved in the post-translational processing of the C-terminal propeptide of SH-EP was isolated from the microsomes of cotyledons of V. muno seedlings. cDNA sequence for the protease indicated that the enzyme is a member of the papain superfamily. Immunocytochemistry and subcellular fractionation of cotyledon cells suggested that the protease was localized in both the ER and protein storage vacuoles as enzymatically active mature form. In addition, protein fractionations of the cotyledonary microsome and Sf9 cells expressing the recombinant protease indicated that the enzyme associates with the microsomal membrane on the luminal side. The protease was named membrane-associated cysteine protease, MCP. The possibility that a papain-type enzyme, MCP, exists as mature enzyme in both ER and protein storage vacuoles will be discussed.

Amino Acid Sequence↗
PubMed2001

Degradation of ribulose-bisphosphate carboxylase by vacuolar enzymes of senescing French bean leaves: immunocytochemical and ultrastructural observations.

The possible involvement of vacuolar cysteine proteinases in degradation of ribulose-bisphosphate carboxylase (Rubisco) in senescing French bean leaves was studied by ultrastructural and immunocytochemical analyses with antibodies raised against the large subunit (LSU) of Rubisco and SH-EP, a cysteine proteinase from Vigna mungo that is immunologically identical to one of the major proteinases of French bean plants. Primary leaves of 10-day-old plants were detached and placed at 25 degrees C in darkness for 0, 4, and 8 days to allow their senescence to proceed. The leaves at each senescence stage were subjected to the conventional electron microscopic and immunocytochemical studies. The results indicated that the chloroplasts of senescing French bean leaves were separated from the cytoplasm of the cell periphery and taken into the central vacuole and that the Rubisco LSU in the chloroplasts was degraded by vacuolar enzymes such as an SH-EP-related cysteine proteinase that developed in senescing leaves. The present results together with the results of previous biochemical studies using vacuolar lysates support the view that Rubisco is degraded through the association of chloroplasts with the central vacuole during the senescence of leaves that were detached and placed in darkness.

Aging↗
PubMed2001

Protective effect of OK-432 on mice against endotoxemia and infection with Pseudomonas aeruginosa and Salmonella enteritidis.

OK-432 has been used clinically as a biological response modifier for cancer therapy. We investigated here the protective effects of OK-432 against endotoxic shock and infectious death caused by Pseudomonas aeruginosa and Salmonella enteritidis in mice and proposed a possible mechanism. Pretreatment of OK-432 reduced the lethality of lipopolysaccharide (LPS)-induced endotoxic shock in D-(+)-galactosamine-sensitized C3H/HeN mice. OK-432 did not affect the TNFalpha production in blood, but it did decrease the susceptibility to TNFalpha. Furthermore, an acceleration of LPS clearance from blood was detected. The pretreatment of OK-432 also decreased the lethality of mice in bacterial infection caused by P. aeruginosa and S. enteritidis. The rapid decrease of the viable bacteria from the circulating blood and in spleen and liver in mice was observed in a manner similar to LPS clearance. These findings indicate that the protective effect of OK-432 against the endotoxemia and bacteremia may depend on an up-regulation of clearance of LPS and bacteria and the augmented resistance to TNFalpha.

Animals↗
PubMed2000

Mass transport of proform of a KDEL-tailed cysteine proteinase (SH-EP) to protein storage vacuoles by endoplasmic reticulum-derived vesicle is involved in protein mobilization in germinating seeds.

A vacuolar cysteine proteinase, designated SH-EP, is expressed in the cotyledon of germinated Vigna mungo seeds and is responsible for the degradation of storage proteins. SH-EP is a characteristic vacuolar proteinase possessing a COOH-terminal endoplasmic reticulum (ER) retention sequence, KDEL. In this work, immunocytochemical analysis of the cotyledon cells of germinated V. mungo seeds was performed using seven kinds of antibodies to identify the intracellular transport pathway of SH-EP from ER to protein storage vacuoles. A proform of SH-EP synthesized in ER accumulated at the edge or middle region of ER where the transport vesicle was formed. The vesicle containing a large amount of proSH-EP, termed KV, budded off from ER, bypassed the Golgi complex, and was sorted to protein storage vacuoles. This massive transport of SH-EP via KV was thought to mediate dynamic protein mobilization in the cotyledon cells of germinated seeds. We discuss the possibilities that the KDEL sequence of KDEL-tailed vacuolar cysteine proteinases function as an accumulation signal at ER, and that the mass transport of the proteinases by ER-derived KV-like vesicle is involved in the protein mobilization of plants.

Animals↗
PubMed2000

Abnormal expression of brain-derived neurotrophic factor and its receptor in the corticolimbic system of schizophrenic patients.

Previous neuropathological studies have revealed that the corticolimbic system of schizophrenic patients expresses abnormal levels of various synaptic molecules, which are known to be influenced by the neuronal differentiation factors, neurotrophins. Therefore, we determined levels of neurotrophins and their receptors in the postmortem brains of schizophrenic patients and control subjects in relation to molecular impairments in schizophrenia. Among the neurotrophins examined, levels of brain-derived neurotrophic factor (BDNF) were elevated specifically in the anterior cingulate cortex and hippocampus of schizophrenic patients, but levels of nerve growth factors and neurotrophin-3 showed no change in any of the regions examined. In parallel, the expressions of TrkB receptor and calbindin-D, which are both influenced by BDNF, were reduced significantly in the hippocampus or the prefrontal cortex. However, neuroleptic treatment did not appear to mimic the neurotrophic change. Neither withdrawal of drug treatment in patients nor chronic administration of haloperidol to rats altered levels of BDNF. These findings suggest that neurotrophic abnormality is associated with the corticolimbic structures of schizophrenic patients and might provide the molecular substrate for pathological manifestations of the illness.

Adult↗
PubMed1999

14-3-3 protein eta chain gene (YWHAH) polymorphism and its genetic association with schizophrenia.

Recent genetic analyses have suggested a linkage between schizophrenia and the chromosomal region 22q12-q13. 14-3-3 protein, abundant in the brain, mediates interactions between diverse molecules of biological activities; its gene was recently mapped to chromosome 22q12.1-q13.1. We therefore investigated allele frequencies of a variable number of tandem repeat (VNTR) in the 5'-noncoding region of the 14-3-3 eta chain gene in controls and schizophrenics. The frequencies of the two-repeat allele were significantly higher (P < 0.05) in the schizophrenics, and particularly in those with onset before age 22 (early-onset schizophrenics, P < 0.02), than in the controls. The odds ratio was significantly increased in the early-onset schizophrenics homozygous for the two-repeat allele (OR = 3.3, 95% CI = 1.1-9.7). The 14-3-3 eta chain gene is a potential susceptibility gene for schizophrenia, and particularly for early-onset schizophrenia.

14-3-3 Proteins↗
PubMed1998

Immunohistochemical changes of the transcription regulatory factors in rat striatum after methamphetamine administration.

We have found evidence for cyclic adenosine monophosphate (cAMP) response element (CRE) in the 5'-upstream region of the human 14.3.3 eta chain gene during studies on isolation and structure of animal brain 14.3.3 cDNA and the human 14.3.3 eta chain gene. cAMP response element-binding protein (CREB) and phosphorylated CREB (pCREB) may bind to this CRE. Since it was considered that these CREBs may play an important role in molecular mechanisms in the brain of animals treated with methamphetamine, we examined the express of CREB and pCREB in rat brain after acute and chronic methamphetamine administrations using antibodies against CREB and pCREB. We observed findings for change in the expression of these factors. Our findings should be discussed in relation to the data of other authors.

Animals↗
PubMed1998

A caspase inhibitor protects thymocytes from diverse signal-mediated apoptosis but not from clonal deletion in fetal thymus organ culture.

A family of caspases has been implicated as an effector in various forms of apoptosis. The present study investigated whether this family of proteases is involved in the induction of intrathymic clonal deletion in comparison with apoptosis induced in the thymus by various signals. Potent apoptosis of thymocytes was induced in fetal thymus organ cultures (FTOC) when FTOC were treated with glucocorticoid, radiation, and anti-CD3 monoclonal antibody (mAb). As a model of negative selection based on apoptotic clonal deletion, the elimination of Vbeta8-expressing thymocytes was induced by inoculating Staphylococcal enterotoxin B (SEB) into FTOC. Addition of a peptide-based caspase inhibitor resulted in the protection of thymocytes from apoptosis induced by glucocorticoid, radiation, and anti-CD3 mAb. In contrast, the same treatment failed to prevent clonal deletion of Vbeta8high thymocytes. These results suggest that different pathways of cell death operate in the thymus that may be distinguished depending on the caspase/protease utilized in each pathway.

Amino Acid Chloromethyl Ketones↗