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Biomedical subjects

Yasuhiro Yamada

Publications and source records attributed to Yasuhiro Yamada.

At least 37 records · Page 2Linked to original sources

Use of restraint in a general hospital psychiatric unit in Japan.

Few analyses have been carried out in Japan concerning factors contributing to physical restraint of patients. We compared demographic data for 241 inpatients who were restrained during a 4-year period with data for 1093 inpatients who were not restrained in a general hospital psychiatric unit in Japan. Increased likelihood of restraint use was associated with older age, male gender, off-hours admission, involuntary hospitalization, transfer from other departments of the hospital, frequent hospitalization, absence of previous treatment, physical complications, history of suicide attempts, organic mental disorders, mental and behavioral disorders from psychoactive substance use, schizophrenia, schizotypal and delusional disorders. Importantly, physical complications not only were more prevalent among restrained than unrestrained patients, but additionally in restrained patients physical complications were associated with more prolonged hospitalization and periods under restraint than were associated with assaultive behavior or periods of unconsciousness. In conclusion, general hospital psychiatric units in Japan often treat patients with psychiatric disorders or symptoms that were associated with physical problems. Particular caution is needed in deciding whether such patients should be restrained since hospitalization may be prolonged or functional status compromised.

Adult↗

Active lactonizing lipase (LipL) efficiently overproduced by Pseudomonas strains as heterologous expression hosts.

Pseudomonas sp. strain 109 secretes lactonizing lipase (LipL), which catalyzes efficient intramolecular transesterification of omega-hydroxyfatty acid esters to form macrocyclic lactones. Because Escherichia coli was found to be unsuitable as an expression host due to the predominant formation of inactive LipL-inclusion bodies and a lack of proper secretion machinery which is also required for the formation of active LipL, Pseudomonas strains were surveyed as expression hosts. Pseudomonas sp. strain 109, an original LipL producer, showed a 7.1-fold higher level of active LipL when the lipL gene under the control of tac-lacUV5 tandem promoter was introduced together with a limL gene encoding a LipL-specific chaperon. Pseudomonas aeruginosa ADD 1976 containing a T7 RNA polymerase gene in the chromosome and plasmid-borne lipL-limL genes under the control of T7 promoter showed a 13-fold higher level of active LipL. Several combinations in the number of lipL and/or limL genes on the plasmid were investigated, and (lipL)3-limL was found to be most efficient, yielding a 67-fold greater production of active LipL than that obtained by the wild-type Pseudomonas sp. strain 109.

Bacterial Proteins↗

Production of hydroxycitric acid by microorganisms.

Hydroxycitric acid (HCA) is a major acid component of the tropical plants Garcinia cambogia and Hibiscus subdariffa. (2S,3S)-HCA from G. cambogia was shown to be a potent inhibitor of ATP citrate lyase (EC4.1.3.8), which catalyzes the extramitochondrial cleavage of citrate to oxaloacetate and acetyl-CoA. (2S,3R)-HCA from H. subdariffa inhibits alpha-amylase and alpha-glucosidase, leading to reduction of carbohydrate metabolism. The availability of HCA is limited by the restricted habitat of the plants as well as the difficulty of stereoselective organic synthesis. Hence, we screened microorganisms producing HCA to find an alternative source of optically pure bulk HCA. Two strains, Streptomyces sp. U121 and Bacillus megaterium G45C, were screened by HPLC analysis. Particular metabolites were purified from their culture broths and compared with authentic HCA from plants. NMR studies indicated that the products are identical to Hibiscus-type HCA. This is the first report showing isolation of microorganisms producing HCA.

Bacillus megaterium↗

Hb KOCHI [beta141(H19)Leu-->Val (g.1404 C-->G); 144-->146(HC1-3)Lys-Tyr-His-->0 (g.1413 A-->T)]: a new variant with increased oxygen affinity.

A novel hemoglobin (Hb) variant was found in a specimen that showed an unusual profile in analyses of glycohemoglobin An abnormal beta-globin, 443 Da smaller than normal beta-globin, was detected by electrospray ionization mass spectrometry (ESI/MS) with intact globin. Mass spectrometry analysis of tryptic peptides derived from isolated abnormal Hb showed an abnormal peptide, characterized as betaT- 14 (141Leu-->Val and 144Lys-->0). Nucleotide sequencing revealed a heterozygosity of codon 141 CTG(Leu)-->GTG(Val), and codon 144 AAG(Lys)-->TAG(stop codon). The isopropanol stability test was normal. We named this novel variant Hb Kochi for the district where it was found. Functional studies carried out on diluted whole hemolysates and isolated Hb components from the proband demonstrated an increased oxygen affinity, consistent with the existence of mild erythrocytosis.

Amino Acid Substitution↗

Suppression of beta-catenin mutation by dietary exposure of auraptene, a citrus antioxidant, in N,N-diethylnitrosamine-induced hepatocellular carcinomas in rats.

Alteration of beta-catenin expression in hepatocellular carcinomas (HCCs) may play an important role in tumor progression by stimulating cell proliferation. We have previously reported that auraptene (AUR), an antioxidant agent isolated from citrus fruit, effectively inhibits chemically induced hepatocarcinogenesis in rats. In this study, we investigated the molecular mechanism of the inhibitory effects of dietary supplementation with AUR on N,N-diethylnitrosamine (DEN)-initiated hepatocarcinogenesis. Male F344 rats initiated with DEN were fed the AUR-containing diet during either the initiation stage (initiation feeding for 7 weeks) or post-initiation phase (post-initiation feeding for 25 weeks) of hepatocarcinogenesis. Liver tumors >5 mm in diameter were used for the analysis of beta-catenin gene mutation and beta-catenin protein expression. After PCR amplification of exon 2 of the beta-catenin gene, the products were sequenced directly. Mutations in the beta-catenin gene were detected in 8 of 24 HCCs (33.3%) in the DEN alone group, 7 of 15 HCCs (46.7%) in the DEN + AUR (initiation feeding) group, and 0 of 8 HCCs (0%) in the DENright curved arrow AUR (post-initiation feeding) group. No mutations of beta-catenin gene were detected in liver cell adenomas of any group. These results demonstrate that AUR exposure in post-initiation period suppresses the occurrence of HCCs with beta-catenin mutation, presumably by negative selection for neoplastic cells harboring the mutation.

Animals↗

Nuclear cloning of embryonal carcinoma cells.

Embryonal carcinoma (EC) cells have served as a model to study the relationship between cancer and cellular differentiation given their potential to produce tumors and, to varying degrees, participate in embryonic development. Here, nuclear transplantation was used to assess the extent to which the tumorigenic and developmental potential of EC cells is governed by epigenetic as opposed to genetic alterations. Nuclei from three independent mouse EC cell lines (F9, P19, and METT-1) with differing developmental and tumorigenic potentials all were able to direct early embryo development, producing morphologically normal blastocysts that gave rise to nuclear transfer (NT)-derived embryonic stem (ES) cell lines at a high efficiency. However, when tested for tumor or chimera formation, the resulting NT ES cells displayed an identical potential as their respective donor EC cells, in stark contrast to previously reported NT ES cells derived from transfer of untransformed cells. Consistent with this finding, comparative genomic hybridization identified previously undescribed genetic lesions in the EC cell lines. Therefore, nonreprogrammable genetic modifications within EC nuclei define the developmental and tumorigenic potential of resulting NT ES cells. Our findings support the notion that cancer results from the deregulation of stem cells and further suggest that the genetics of ECs will reveal genes involved in stem cell self-renewal and pluripotency.

Animals↗

Reprogramming of a melanoma genome by nuclear transplantation.

We have used nuclear transplantation to test whether the reprogramming activity of oocytes can reestablish developmental pluripotency of malignant cancer cells. We show here that the nuclei of leukemia, lymphoma, and breast cancer cells could support normal preimplantation development to the blastocyst stage but failed to produce embryonic stem (ES) cells. However, a blastocyst cloned from a RAS-inducible melanoma nucleus gave rise to ES cells with the potential to differentiate into multiple cell types in vivo including melanocytes, lymphocytes, and fibroblasts. Chimeras produced from these ES cells developed cancer with higher penetrance, shorter latency, and an expanded tumor spectrum when compared with the donor mouse model. These results demonstrate that the secondary changes of a melanoma nucleus are compatible with a broad developmental potential but predispose mice to melanomas and other malignant tumors on reactivation of RAS. Our findings serve as a paradigm for studying the tumorigenic effect of a given cancer genome in the context of a whole animal.

Animals↗

Anomalous Hall effect governed by electron doping in a room-temperature transparent ferromagnetic semiconductor.

Ferromagnetic semiconductors are believed to be suitable for future spintronics, because both charge and spin degrees of freedom can be manipulated by external stimuli. One of the most important characteristics of ferromagnetic semiconductors is the anomalous Hall effect. This is because the ferromagnetically spin-polarized carrier can be probed and controlled electrically, leading to direct application for electronics. Control of the Curie temperature and magnetization direction by electronic field, and photo-induced ferromagnetism have been performed successfully using the anomalous Hall effect for group III-V ferromagnetic semiconductors. In these cases, the operation temperature was much below room temperature because of the limited Curie temperature of less than 160 K (ref. 6). Here, we report on the anomalous Hall effect governed by electron doping in a room-temperature transparent ferromagnetic semiconductor, rutile Ti(1-x)Co(x)O(2-delta) (of oxygen deficiency delta). This result manifests the intrinsic nature of ferromagnetism in this compound, and represents the possible realization of transparent semiconductor spintronics devices operable at room temperature.

Journal Article↗

Role of tumor necrosis factor-alpha in methamphetamine-induced drug dependence and neurotoxicity.

Tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine, is now emerging as an important modulator of the function of the CNS. Methamphetamine (METH) is a widely abused psychostimulant that causes euphoria, hyperactivity, and drug dependence. High doses of METH cause long-term neurotoxicity in dopaminergic neurons. In this study, we investigated a role of TNF-alpha in METH-induced dependence and neurotoxicity. Repeated treatment with METH (2 mg/kg for 5 d) in rats induced a significant increase in TNF-alpha mRNA and protein expression in the brain. Exogenous TNF-alpha (1-4 microg) blocked locomotor-stimulating and rewarding effects of METH, as well as METH (4 mg/kg; four times at 2 hr intervals)-induced dopaminergic neurotoxicity in mice. To examine a role of endogenous TNF-alpha in behavioral and neurochemical effects of METH, we used mice with targeted deletions of the TNF-alpha gene. TNF-alpha-(-/-) mice showed enhanced responses to the locomotor-sensitizing, rewarding, and neurotoxic effects of METH compared with wild-type mice. We also examined the role of TNF-alpha in METH-induced dopamine (DA) release and uptake in vitro and in vivo in C57BL/6 mice. Exogenous TNF-alpha (4 microg) attenuated the METH-induced increase in extracellular striatal DA in vivo and potentiated striatal DA uptake into synaptosomes in vitro and in vivo. Furthermore, TNF-alpha activated vesicular DA uptake by itself and diminished the METH-induced decrease in vesicular DA uptake. Our findings suggest that TNF-alpha plays a neuroprotective role in METH-induced drug dependence and neurotoxicity by activating plasmalemmal and vesicular DA transporter as well as inhibiting METH-induced increase in extracellular DA levels.

Animals↗

Enhancement of development of azoxymethane-induced colonic premalignant lesions in C57BL/KsJ-db/db mice.

Epidemiological studies have shown that obesity and diabetes mellitus may be risk factors for colon cancer. However, the underlying mechanisms of how these chronic diseases promote colon carcinogenesis remain unknown. C57BL/KsJ-db/db mice have obese and diabetic phenotypes because of disruption of the leptin receptor. The present study was designed to investigate whether development of azoxymethane (AOM)-induced dysplastic and early neoplastic (premalignant) lesions of the colon is modulated in db/db mice. Homozygous db/db mice, heterozygous db/+ mice and littermate controls (+/+) were injected with AOM under food restriction ( approximately 10.8 kcal/mouse/day) and killed 5 weeks after the carcinogen treatment. Their colons were assessed for premalignant lesions induced by AOM. We found a significant increase in the multiplicity of the total premalignant lesions in db/db mice when compared with db/+ or +/+ mice. Phenotypically, serum leptin and insulin levels in db/db mice were significantly higher than those in db/+ or +/+ mice, whereas the body weights and glucose levels in blood of db/db, db/+ and +/+ mice were comparable. In addition, immunostaining of the leptin receptor and insulin-like growth factor-I receptor showed up-regulation of these protein levels specifically in the lesions. Our data indicate that development of AOM-induced premalignant lesions is enhanced in db/db mice with hyperleptinemia and hyperinsulinemia. The results have important implications for further exploration of the possible underlying events that affect the positive association between colon cancer and chronic diseases (obesity and diabetes).

Animals↗

Inflammatory pseudotumor of the liver: ferumoxide-enhanced MR imaging as a tiebreaker.

We examined a 70-year-old male patient with an inflammatory pseudotumor of the liver mimicking a peripheral-type cholangiocellular carcinoma. Ferumoxide-enhanced magnetic resonance (MR) imaging revealed residual Kupffer cell function in liver parenchyma in and surrounding the inflammatory pseudotumor involvement, which suggested the diagnosis of inflammatory pseudotumor of the liver. We correlate the MR imaging and pathologic findings in this report.

Aged↗

Aberrant crypt foci and beta-catenin accumulated crypts; significance and roles for colorectal carcinogenesis.

Preneoplastic or precancerous lesions in the large bowel have been characterized in terms of morphology and histochemical phenotype. However, the detailed histogenesis and relation of particular lesions to malignancies has not yet to be unequivocally clarified. Aberrant crypt foci (ACF), identified in whole-mount preparations of colonic mucosa in rodents and also recognized in human colon, are now frequently used as effective surrogate biomarkers for experimentally detection of chemopreventive agents against colorectal cancers, but the preneoplastic or precancerous nature of ACF in rodents and humans still remains inconclusive. Relatively recently, early appearing beta-catenin accumulated crypts (BCAC) have been described in en face preparations of colonic mucosa in rodents which differ from ACF in many features. BCAC are suggested to be premalignant rather than preneoplastic. The pathological significance of both lesions, including their advantages and disadvantages as surrogate end points for large bowel neoplasms, and roles in colorectal carcinogenesis are discussed here.

Animals↗

Histological and immunohistochemical observations of mucin-depleted foci (MDF) stained with Alcian blue, in rat colon carcinogenesis induced with 1,2-dimethylhydrazine dihydrochloride.

The usefulness of mucin-depleted foci (MDF), which have recently been proposed as a new preneoplastic biomarker in rat colon carcinogenesis, was histologically investigated in rat colonic tissues treated with 1,2-dimethylhydrazine dihydrochloride (DMH). The relationship among aberrant crypt foci (ACF), MDF and beta-catenin accumulated crypts (BCAC) was examined by comparing the corresponding computer-captured images. Twelve male F344 rats were given DMH s.c. at a dose of 40 mg/kg body weight, once a week for 2 weeks, and randomly divided into two groups. Rats in group 1 were given normal drinking water, while those in group 2 were given drinking water containing indomethacin (IND) at 16 ppm for 6 weeks. All animals were sacrificed 8 weeks after the first DMH treatment. The resected colons were fixed in 10% formalin, and stained with Alcian blue for observation of ACF and MDF. Histological and immunohistochemical analysis revealed that the numbers of ACF, MDF and overlapping lesions in group 2 (treated with IND) were significantly decreased, compared with those in group 1. The number of BCAC in group 2 was also significantly lower than that in group 1. The reduction (61.5%) of MDF by IND was much greater than that (29.3%) of ACF. Analyses of the computer-captured images indicated that MDF had more frequent dysplastic changes and overexpression of beta-catenin than did ACF. MDF having over 4 crypts or MDF with the appearance of ACF corresponded well to BCAC. These results suggest that MDF may be useful as an early biomarker in colon carcinogenesis.

1,2-Dimethylhydrazine↗

Tumor formation is correlated with expression of beta-catenin-accumulated crypts in azoxymethane-induced colon carcinogenesis in mice.

We have reported that beta-catenin-accumulated crypts (BCAC) are independent of aberrant crypt foci (ACF) in the colonic mucosa of rats exposed to colorectal carcinogens, and we suggested that they may be premalignant lesions. In the present study, we performed a comparative study on the formation of the two types of early-appearing lesions (BCAC and ACF), and tumors of the colon in two mouse strains with different susceptibility to azoxymethane (AOM). SWR/J mice are known to be relatively susceptible to AOM, whereas AKR/J mice are reported to be virtually resistant. Both AKR/J and SWR/J mice, 6 weeks old, received subcutaneous injections of AOM (15 mg/kg body weight) once a week for 3 weeks, and were sacrificed at 16 and 41 weeks of age. Colons of the animals sacrificed at 16 and 41 weeks of age were processed to examine expression of the early-appearing lesions and neoplasms. Although AKR/J mice had a lower incidence of colonic tumors than SWR/J mice did, AKR/J mice showed a similar frequency of ACF to that in SWR/J mice. In both strains, ACF were detected at high frequency in the proximal colon, whereas tumors developed mainly in the distal colon. Importantly, the incidence of BCAC in SWR/J mice was significantly higher than that in AKR/J mice, and the highest frequency was observed in the distal segments of the colon. These results support the idea that BCAC are a reliable surrogate endpoint for colon carcinogenesis in mice.

Adenocarcinoma↗

Dietary supplementation of the citrus antioxidant auraptene inhibits N,N-diethylnitrosamine-induced rat hepatocarcinogenesis.

OBJECTIVES: We have previously reported that an antioxidant, auraptene (AUR), isolated from citrus fruit effectively inhibits chemically induced carcinogenesis in digestive tracts, such as the oral cavity, esophagus and large bowel. In this study, we investigated the modifying effects of dietary supplementation with AUR on N,N-diethylnitrosamine (DEN)-initiated hepatocarcinogenesis in male F344 rats in two different experiments to determine whether the compound exerts a cancer-chemopreventive action in other organs. METHODS: In the first experiment, animals were fed diets containing AUR at dose levels of 100 and 500 ppm for 7 weeks 1 week before, during, and 1 week after the start of liver carcinogenesis induced by DEN (40 ppm in drinking water for 5 weeks) to predict the modulatory effect on hepatocarcinogenesis. After 7 weeks, the numbers of hepatocellular enzyme-altered foci (EAF; cm(2)) which stained positive for the placental form of glutathione S-transferase (GST-P) and transforming growth factor (TGF)-alpha were determined on immunohistochemically stained sections. In the second experiment conducted to confirm the findings, animals subjected to DEN treatment were fed AUR-containing diets (100 and 500 ppm) during either the initiation stage ('initiation' feeding for 7 weeks) or post-initiation phase ('post-initiation' feeding for 25 weeks) of DEN-induced hepatocarcinogenesis. RESULTS: In the first experiment, feeding with AUR at both doses during DEN exposure decreased the mean numbers of GST-P-positive and TGF-alpha-positive EAF/cm(2), and the reduction in the number of TGF-alpha-positive EAF by feeding 500 ppm AUR was statistically significant (p < 0.005). In the second experiment, the 'initiation' feeding with 500 ppm AUR significantly inhibited the incidence (33 vs. 83%, p = 0.000511) and multiplicity (0.67 +/- 1.09 vs. 1.96 +/- 1.85, p < 0.005) of liver cell carcinoma. Also, the 'post-initiation' feeding with AUR at both doses significantly reduced the development of hepatocellular carcinoma (100 ppm: incidence, 15%, p = 0.000006; multiplicity: 0.25 +/- 0.64, p < 0.001; 500 ppm: incidence, 11%, p = 0.000002; multiplicity, 0.26 +/- 0.81, p < 0.001). In addition, AUR feeding reduced cell proliferation and the apoptotic index in liver cell neoplasms. CONCLUSIONS: The results suggest that the citrus antioxidant AUR is a potential chemopreventive agent against DEN-induced hepatocarcinogenesis in rats.

Animals↗

Genotyping of hepatitis C virus by melting curve analysis with SYBR Green I.

BACKGROUND: Recent studies have focused on whether different hepatitis C virus (HCV) genotypes are associated with different profiles of pathogenicity, infectivity, and response to antiviral therapy. We needed to develop a convenient screening test for HCV genotypes 1 and 2. METHOD: We tested 55 patients with known chronic HCV infection. Viral RNA was extracted from serum samples using an automatic viral RNA purification system, and HCV genotypes were determined by reverse transcriptase-polymerase chain reaction using LightCycler melting curve analysis with SYBR Green I. RESULTS: HCV RNA was detected in all samples and each genotype was determined. The mean (standard deviation) melting temperatures for subtypes 1b (n = 32), 2a (n = 15) and 2b (n = 8) were 93.14 degrees C (0.51 degrees C), 91.08 degrees C (0.49 degrees C) and 91.77 degrees C (0.27 degrees C), respectively. Genotypes 1 and 2 were differentiated within 3 h by this method. CONCLUSIONS: Our melting curve analysis is a rapid and convenient screening test for differential identification of HCV genotypes 1 and 2.

Benzothiazoles↗

Identification by gene deletion analysis of barB as a negative regulator controlling an early process of virginiamycin biosynthesis in Streptomyces virginiae.

The Streptomyces virginiae gamma-butyrolactone autoregulator virginiae butanolide is a low-molecular-weight Streptomyces hormone eliciting virginiamycin biosynthesis through its binding to the specific receptor protein, BarA. Immediately downstream of barA lies barB, the transcription of which is tightly repressed by BarA in the absence of virginiae butanolide and derepressed in its presence. Thus, BarB is next to BarA on the virginiae butanolide-BarA signaling cascade. An in-frame 279-bp deletion was introduced into the barB allele, which rendered it inactive by eliminating the majority of the coding region, including the helix-turn-helix DNA-binding motif. No significant change was observed with the Delta barB mutant with respect to the timing or amount of virginiae butanolide production, or the morphological differentiation on solid media, indicating that barB neither participates in virginiae butanolide biosynthesis nor in cytodifferentiation. In contrast, analysis of virginiamycin production in the Delta barB mutant revealed that production of both virginiamycin M(1) and virginiamycin S occurred immediately after virginiae butanolide production, 2-3 h earlier than in the wild-type strain, indicating that BarB participates in the temporal retardation of virginiamycin production after virginiae butanolide inactivates the repressor function of BarA. RT-PCR analysis of the transcription of several genes surrounding barA-barB by the Delta barB mutant indicated that BarB plays a negative regulatory role, directly or indirectly, in the transcription of barZ, vmsR, and orf5 located upstream of barB.

Amino Acid Sequence↗

Pre-cancerous lesions for colorectal cancers in rodents: a new concept.

It is widely believed that colorectal carcinogenesis is a representative multi-step tumorigenesis with events of genetic alterations. Aberrant crypt foci (ACF) recognized on the surface of cancer-predisposed colons of rodents have been regarded as early-appearing pre-neoplastic lesions. However, it is not clear if such lesions are truly pre-cancerous lesions for colorectal cancers in rodents. Recently, beta-catenin-accumulated crypts (BCAC) were identified in colonic mucosa at the early stages of colon carcinogenesis. Accumulating evidence indicates that they are independent small dysplastic lesions of ACF. Here we discuss the importance of BCAC as pre-cancerous lesions in colon carcinogenesis.

Animals↗