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Biomedical subjects

T Yoshizawa

Publications and source records attributed to T Yoshizawa.

At least 19 recordsLinked to original sources
PubMed2005

Microbiological and physicochemical factors affecting Aspergillus section Flavi incidence in Cavendish banana (Musa cavendishii) chips production in Southern Philippines.

Microbiological and physicochemical factors affecting the incidence of Aspergillus section Flavi in dried Cavendish banana (Musa cavendishii) chips production in Southern Philippines were examined. The average counts of Aspergillus section Flavi (AFC) in fresh and dried Cavendish bananas from 10 production batches of the Philippine Agro-Industrial Development Cooperative in Davao del Norte, Southern Philippines were 1.2 x 10(2) and 1.6 x 10(2) cfu/g, respectively. Isolates from both samples were identified to be Aspergillus flavus based on spore type and conidial structure of isolates. An increasing trend in the AFC of Cavendish bananas was observed during dried banana chips processing. Variability in the AFC between production batches was attributed to differences in aerobic and fungal populations and physicochemical characteristics of the fruits, peel damage of the raw materials, concentration of AFC in the air and food-contact surfaces of the production area, and temperature and relative humidity (RH) conditions of the environment during production and storage. Physicochemical characteristics of Cavendish bananas from the receipt of raw materials up to the first day of drying were within the reported range of values allowing growth and toxin production by aflatoxigenic fungi. Air-borne AFC varied depending on the section of the production area examined. The close proximity of the waste disposal area from the production operation to the preparation, drying and storage areas suggests that cross-contamination, probably air-borne or insect-borne was a likely occurrence. The hands of workers were also identified as AFC sources. Results of this study highlight the need for the development of strategies to control aflatoxigenic fungi and aflatoxin contamination in Philippine dried Cavendish bananas.

Air Microbiology↗
PubMed2005

Evaluation of a method to determine the natural occurrence of aflatoxins in commercial traditional herbal medicines from Malaysia and Indonesia.

Traditional herbal medicines, popularly known as 'jamu' and 'makjun' in Malaysia and Indonesia, are consumed regularly to promote health. In consideration of their frequent and prolonged consumption, the natural occurrence of aflatoxins (AF) in these products was determined using immunoaffinity column clean-up and high-performance liquid chromatography with pre-column derivatization. The evaluated method, which entails dilution of sample extracts with Tween 20-phosphate buffered saline (1:9, v/v) and a chromatographic system using isocratic mobile phase composed of water-methanol-acetonitrile (70:20:10, v/v/v), was effective in separating AFB1, AFG1 and AFG2 from interference at their retention times. Results were confirmed using post-column derivatization with photochemical reactor. For 23 commercial samples analyzed, mean levels (incidence) of AFB(1), AFB(2) and AFG1 in positive samples were 0.26 (70%), 0.07 (61%) and 0.10 (30%) microg/kg, respectively; one sample was positive for AFG2 at a level of 0.03 (4%) microg/kg. In contrast to the high levels of AF in crude herbal drugs and medicinal plants reported previously by other researchers, the low contamination levels reported in this study may be attributed to the higher selectivity to AF of the method applied. Based on the AFB1 levels and the daily consumption of positive samples, a mean probable daily intake of 0.022 ng/kg body weight was calculated.

Aflatoxins↗
PubMed2004

Occurrence of aflatoxin M1 in domestic milk in Japan during the winter season.

A total of 208 samples of commercial pasteurized milk gathered from retail outlets across Japan during the winter season were analysed for aflatoxin M1 (AFM1). Japan was divided into 11 regions from north to south, and nine to 45 milk samples from each region were randomly purchased between December 2001 and February 2002. Each milk sample was cleaned up by an immunoaffinity column, and AFM1 was quantified by liquid chromatography with fluorescence detection in four independent laboratories. The limit of detection of the method was 0.001 microg kg(-1). The identity of the putative AFM1 in milk sample was confirmed by the formation of AFM1 hemi-acetal with trifluoroacetic acid. Based on the results obtained with spiked samples (0.05 microg AFM1 kg(-1)), the mean recovery was 91.4%, the relative standard deviation for repeatability was 4.6%, and the relative standard deviation for reproducibility was 8.0% among four independent laboratories. AFM1 was detected in 207 (99.5%) of 208 milk samples at 0.001-0.029 microg kg(-1), with a mean of 0.009 microg kg(-1) and a 90th percentile of 0.014 microg kg(-1). No significant difference of the level of AFM1 contamination was observed among the regions.

Aflatoxin M1↗
PubMed2004

Menopause in Australia and Japan: effects of country of residence on menopausal status and menopausal symptoms.

OBJECTIVES: The aim of the study was to explore the effects of country of residence on menopausal status and menopausal symptoms in Australian and Japanese women. The study objectives included exploring the impact of country of residence (Australia and Japan) and menopausal status on menopausal symptoms, and identifying whether country of residence (Australia and Japan) moderates the relationship between menopausal status and menopausal symptoms. METHODS: Analyses are based on 1743 women aged between 40 and 60 years who participated in the multi-race, multi-site, cross-sectional study of mid-aged women called the Australian and Japanese Midlife Women's Health Study (AJMWHS) in 2001--2002. Study participants completed a mailed questionnaire that contained questions on a variety of health-related topics. RESULTS: In both cultures there was a similar increase in prevalence of depression (p < 0.001), somatic symptoms (p < 0.001) and vasomotor symptoms (p < 0.001) at perimenopause. Australian women experienced more night sweats than Japanese women but the prevalence of hot flashes was not statistically different. Postmenopausal Japanese women had more somatic, psychological and sexual symptoms. The main effect for menopausal status and the interaction effect of country of residence was significant in the somatic symptoms (p < 0.001), but not in any of the other areas. CONCLUSIONS: Vasomotor, psychological and somatic symptoms decrease after menopause in Australian women, with only sexual symptoms continuing. In Japanese women, somatic, psychological and sexual symptoms remain high after menopause. It is possible that westernization may be having a significant impact on the aging of women in Japan and it is, therefore important to capture through research just what this impact may be.

Adult↗
PubMed2003

In-house direct cELISA for determining aflatoxin B1 in Thai corn and peanuts.

To overcome the problem of aflatoxins (AF) in Thai foods, a sensitive in-house direct cELISA using monoclonal antibody (mAb) was established and compared with a commercial ELISA kit and thin-layer chromatography for the determination of AFB(1) levels in corn and peanuts. Among eight in-house mAbs (AF1-8), AF5 was used in the direct cELISA owing to its excellent specificity and sensitivity with the detection limit of 4 microg kg(-1). The recovery of AFB(1) spiked at 5, 10, 20, 40 and 80 microg kg(-1) ranged from 88.1 to 99.5%. Correlation coefficients of the ELISA with the commercial ELISA kit and thin-layer chromatography were 0.912 and 0.802 for corn, and 0.941 and 0.832 for peanuts, respectively (p<0.05). The cost per sample was estimated to be about 16 times lower than the commercial ELISA kit. Subsequently, the in-house direct cELISA was successfully applied to screen the contamination of AFB(1) in Thai corn and peanuts. Mean levels of AFB(1) (per cent positive) were 73 microg kg(-1) (85.7%) in corn and 102 microg kg(-1) (67.9%) in peanuts, for which 46.4% of both foods were above the Thailand regulation limit (20 microg kg(-1)).

Aflatoxin B1↗
PubMed2003

Effects of heating procedures on deoxynivalenol, nivalenol and zearalenone levels in naturally contaminated barley and wheat.

The influence of heating temperature and time on deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEA) contents in naturally co-contaminated barley and wheat was investigated intending to establish the basis for a decontamination model of Fusarium mycotoxins in cereals. The standard toxins and whole barley powder samples were heated in a convection oven at 140, 160, 180, 200, or 220 degrees C, and kernel subsamples (200 g each) were roasted in an experimental rotary gas-fired roaster at 150, 180 or 220 degrees C. All treatments resulted in a time-temperature-dependent decomposition of the toxins; the logarithm of the toxin remaining % presented a linear relationship with heating time. The lines equations were used to estimate the half (H) and decimal (D) decomposition times (time required to destroy 50 or 90% of the toxin, respectively). DON and NIV H and D decomposition times were similar and 50% shorter for heated standards than for whole barley powder. ZEA standard values were considerably longer, while whole barley powder values were comparable with those of DON and NIV. At 220 degrees C, D decomposition times of DON, NIV and ZEA heated standards were 11, 10 and 85 min, respectively, while the values obtained in whole barley powder were the same for the three toxins (25 min). The determination of H and D decomposition values constitutes a basis to understand the heating stability nature of each toxin.

Decontamination↗
PubMed2001

A new splicing variant for human tyrosine hydroxylase in the adrenal medulla.

It has been reported that several mRNA isoforms of tyrosine 3-monooxygenase (tyrosine hydroxylase; TH) occur only in primates. New TH isoforms produced by skipping of exon 3 in the adrenal medulla of patients with progressive supranuclear palsy (PSP) have recently been reported, J. Neurochem. 67 (1996) 19. Here, we looked for the presence of new TH isoforms in control brains and adrenal medulla and in brains from patients with PSP. We found a novel type of TH mRNA in the adrenal medulla from one of the control subjects. The mRNA lacked exon 4, resulting in a premature stop codon at amino acid 147. This result suggests the importance of alternative splicing in the regulation of TH activity.

Adrenal Medulla↗
PubMed2001

Complete genome sequence of an aerobic thermoacidophilic crenarchaeon, Sulfolobus tokodaii strain7.

The complete genomic sequence of an aerobic thermoacidophilic crenarchaeon, Sulfolobus tokodaii strain7 which optimally grows at 80 degrees C, at low pH, and under aerobic conditions, has been determined by the whole genome shotgun method with slight modifications. The genomic size was 2,694,756 bp long and the G + C content was 32.8%. The following RNA-coding genes were identified: a single 16S-23S rRNA cluster, one 5S rRNA gene and 46 tRNA genes (including 24 intron-containing tRNA genes). The repetitive sequences identified were SR-type repetitive sequences, long dispersed-type repetitive sequences and Tn-like repetitive elements. The genome contained 2826 potential protein-coding regions (open reading frames, ORFs). By similarity search against public databases, 911 (32.2%) ORFs were related to functional assigned genes, 921 (32.6%) were related to conserved ORFs of unknown function, 145 (5.1%) contained some motifs, and remaining 849 (30.0%) did not show any significant similarity to the registered sequences. The ORFs with functional assignments included the candidate genes involved in sulfide metabolism, the TCA cycle and the respiratory chain. Sequence comparison provided evidence suggesting the integration of plasmid, rearrangement of genomic structure, and duplication of genomic regions that may be responsible for the larger genomic size of the S. tokodaii strain7 genome. The genome contained eukaryote-type genes which were not identified in other archaea and lacked the CCA sequence in the tRNA genes. The result suggests that this strain is closer to eukaryotes among the archaea strains so far sequenced. The data presented in this paper are also available on the internet homepage (http://www.bio.nite.go.jp/E-home/genome_list-e.html/).

Archaeal Proteins↗
PubMed2001

Differential nociceptive responses in mice lacking the alpha(1B) subunit of N-type Ca(2+) channels.

The role of N-type Ca(2+) channels in nociceptive transmission was examined in genetically engineered mice lacking the alpha(1B) subunit of N-type channels and in their heterozygote and wild-type littermates. In alpha(1B)-deficient mice, N-type channel activities in dorsal root ganglion neurons and spinal synaptoneurosomes were eliminated without compensation by other types of voltage-dependent Ca(2+) channels. The alpha(1B)-deficient mice showed a diminution in the phase 2 nociceptive responses more extensively than in the phase 1 nociceptive responses of the formalin test. The alpha(1B)-deficient mice exhibited significantly increased thermal nociceptive thresholds in the hot plate test, but failed to increase mechanical nociceptive thresholds in the tail pinch test. These results suggest a crucial role of N-type channels in nociceptive transmission, especially for persistent pain like phase 2 of the formalin test and for nociception induced by thermal stimuli.

Animals↗
PubMed2001

Foveal translocation with scleral imbrication in patients with myopic neovascular maculopathy.

PURPOSE: To report our surgical results of foveal translocation with scleral imbrication in patients with myopic neovascular maculopathy. DESIGN: Noncomparative, interventional, consecutive case series. METHODS: Ten eyes of 10 myopic patients with subfoveal neovascular membranes that had undergone foveal translocation with scleral imbrication were recruited for this retrospective study. Inclusion criteria were myopia 6.0 diopters or greater in refractive error (or axial length 26.5 mm or longer), subfoveal choroidal neovascularization, and preoperative best-corrected visual acuity of 20/100 or worse. None of these eyes had undergone prior laser photocoagulation or submacular surgery. The main outcome measures were surgical complications and postoperative visual function. RESULTS: Postoperatively, visual acuity had improved more than 3 lines in the logarithm of minimum angle of resolution (logMAR) measurement in all eyes. The mean preoperative, postoperative best, and final visual acuity were 0.12, 0.59, and 0.51, respectively. Of the 10 eyes, six achieved a postoperative final visual acuity of 20/40 or better. The mean postoperative foveal displacement was 0.78 disk diameter (range, 0.3--1.3 disk diameter). Two patients underwent a reoperation because of insufficient foveal displacement. Furthermore, one of these two patients required a third operation to reduce an excessive retinal fold involving the fovea induced by the second surgery. Of the 10 patients, two noted transient diplopia. This complaint, however, resolved over time as suppression developed. Although unintentional iatrogenic retinal tears formed intraoperatively in two eyes, these were successfully treated without serious complications. Postoperatively, mild retinal pigment epithelial changes were observed in all cases, but none led to significant deterioration of visual acuity during the follow-up period. All patients but one were followed for a minimum of 6 months. CONCLUSIONS: In eyes with myopic neovascular maculopathy, foveal translocation with scleral imbrication may be useful in improving visual acuity. Further refinements in surgical technique and assessment of the long-term complications will be needed to make this procedure safer and more useful.

Adult↗
PubMed2001

The properties of convergence eye movements evoked from the rostral and caudal lateral suprasylvian cortex in the cat.

Convergence eye movements were evoked in the lateral suprasylvian cortex (LS cortex) in the cat. Three effective regions were found: the rostral and caudal parts of the postero-medial LS cortex (the PMLS) and the rostral part of the postero-lateral LS cortex (the PLLS). These three areas represent the central and paracentral visual fields in the published retinotopic map (Palmer et al., 1978). Convergence eye movements evoked from the caudal PMLS were divided into two groups based on their latencies; the short-latency components (SLC) and long-latency components (LLC). The SLC and the LLC had differences in their symmetry of right and left eye movements during vergence eye movement. The SLC had symmetric right and left eye components and the LLC had dominant contralateral eye components. In the rostral PMLS, latencies of evoked convergence eye movement were comparable to those of the caudal PMLS, but they did not divided into two groups. Convergence eye movements evoked from the PLLS had longer latencies than those from the PMLS and asymmetric right and left eye components. It is suggested that different subregions in the LS cortex contribute to the control of convergence eye movement, playing different roles.

Animals↗
PubMed2001

Aflatoxins and fumonisins in corn from the high-incidence area for human hepatocellular carcinoma in Guangxi, China.

A comparative study on the natural occurrence of aflatoxins and Fusarium toxins was conducted with corn samples from high- and low-incidence areas for human primary hepatocellular carcinoma (PHC) in Guangxi, China. In samples from the high-risk area, aflatoxin B(1) was the predominant toxin detected in terms of quantity and frequency, with its concentration ranging between 9 and 2496 microg/kg and an 85% incidence of contamination. Among the samples, 13 (76%) exceeded the Chinese regulation of 20 microg/kg for aflatoxin B(1) in corn and corn-based products intended for human consumption. Significant differences in aflatoxin B(1), B(2), and G(1) and total aflatoxin concentrations in corn between the areas were found (P < 0.05). The average daily intake of aflatoxin B(1) from corn in the high-risk area was 184.1 microg, and the probable daily intake is estimated to be 3.68 microg/kg of body weight/day, 3.20 times the TD(50) in rats. Corn samples from both areas were simultaneously contaminated with fumonisins B(1), B(2), and B(3). Aflatoxin B(1) may play an important role in the development of PHC in Guangxi.

Aflatoxin B1↗
PubMed2001

Photoisomerization in rhodopsin.

This article reviews the primary reaction processes in rhodopsin, a photoreceptive pigment for twilight vision. Rhodopsin has an 11-cis retinal as the chromophore, which binds covalently with a lysine residue through a protonated Schiff base linkage. Absorption of a photon by rhodopsin initiates the primary photochemical reaction in the chromophore. Picosecond time-resolved spectroscopy of 11-cis locked rhodopsin analogs revealed that the cis-trans isomerization of the chromophore is the primary reaction in rhodopsin. Then, generation of femtosecond laser pulses in the 1990s made it possible to follow the process of isomerization in real time. Formation of photorhodopsin within 200 fsec was observed by a transient absorption (pump-probe) experiment, which also revealed that the photoisomerization in rhodopsin is a vibrationally coherent process. Femtosecond fluorescence spectroscopy directly captured excited-state dynamics of rhodopsin, so that both coherent reaction process and unreacted excited state were observed. Faster photoreaction of the chromophore in rhodopsin than that in solution implies that the protein environment facilitates the efficient isomerization process. Such contributions of the protein residues have been monitored by infrared spectroscopy of rhodopsin, bathorhodopsin, and isorhodopsin (9-cis rhodopsin) at low temperatures. The crystal structure of bovine rhodopsin recently reported will lead to better understanding of the mechanism in future.

Amino Acid Sequence↗
PubMed2001

Structure-antinociceptive activity studies of incarvillateine, a monoterpene alkaloid from Incarvillea sinensis.

Incarvillateine (1), a new monoterpene alkaloid carrying a characteristic cyclobutane ring, has been found to show significant antinociceptive activity in a formalin-induced pain model in mice. To investigate the correlation between its structure and antinociceptive activity, and especially to study whether a cyclobutane ring is necessary or not for expression of activity, we evaluated the antinociceptive activity of two constructive units of incarvillateine, such as a monoterpene unit (incarvilline, 3) and a phenylpropanoid unit (ferulic acid, 2) in the formalin test, and compared activity of the units with that of incarvillateine. Furthermore, in order to obtain more information about the structure-activity relationships, monoterpene alkaloid derivatives, such as incarvine C (5, a precursor of incarvillateine), incarvine A (4, an ester compound comprised of two monoterpene alkaloids and a monoterpene) and 3,3'-demethoxy-4,4'-dehydroxyincarvillateine (6, a synthetic new compound), were examined. The antinociceptive effect of 3,3'-demethoxy-4,4'-dehydroxyincarvillateine was equal to that of incarvillateine. Meanwhile, the other compounds exhibited no or weak activity. These results suggested that the cyclobutane moiety of incarvillateine plays an important role in expression of antinociceptive action.

Alkaloids↗
PubMed2001

Dietary phosphorus restriction reverses the impaired bone mineralization in vitamin D receptor knockout mice.

Deficiency of vitamin D, which is required for calcium homeostasis, causes rickets with hypocalcemia and hypophosphatemia, resulting in growth retardation and impaired bone formation. Mice lacking the vitamin D receptor (VDR) develop the typical features of rickets, establishing that VDR plays a role in controlling the actions of vitamin D. Normalization of impaired mineral homeostasis in VDR KO mice fed a diet supplemented with high concentrations of calcium (2%) and phosphorus (1.25%) is reported to reverse the malformation of bone and the growth retardation as well. However, the relationship between mobilization of phosphorus and calcium and nuclear control of vitamin D actions remains unclear. The present study was undertaken to determine the effect of dietary phosphorus on mineral mobilization and bone mineralization. We report here that feeding a diet supplemented with a restricted amount of phosphorus (0.25%) and a normal amount of calcium (0.5%) for 4 weeks reverses the growth retardation and the impaired mineralization in VDR KO mice, as does a high-calcium and high-phosphorus diet (Ca: 2%; P: 1.25%). Thus, the present study suggests that mobilization of calcium and mobilization of phosphorus are differentially regulated through vitamin D-dependent and -independent systems, and that intake of calcium and phosphorus in the proper ratio is important for mineral homeostasis and bone mineralization.

Animals↗
PubMed2001

Aberrant growth plate development in VDR/RXR gamma double null mutant mice.

VDR forms heterodimers with one of three RXRs, RXR alpha, RXR beta, and RXR gamma, and it is thought that RXR ligands can also modulate the trans-activation function of VDR/RXR heterodimers. In the present study we generated VDR/RXR gamma double null mutant mice to examine the convergent actions of vitamin D and vitamin A signaling and to explore the possibility of a functionally redundant VDR. Although RXR gamma(-/-) mice exhibited no overt abnormalities, VDR(-/-)/RXR gamma(-/-) mice appeared similar to VDR(-/-) mice, showing features typical of vitamin D-dependent rickets type II, including growth retardation, impaired bone formation, hypocalcemia, and alopecia. However, compared to VDR(-/-) mice, growth plate development in VDR(-/-)/RXR gamma(-/-) mutant mice was more severely impaired. Normalizing mineral ion homeostasis through dietary supplementation with high calcium and phosphorous effectively prevented rachitic abnormalities, except for disarranged growth plates in VDR(-/-)/RXR gamma(-/-) mutant mice, and alopecia in both VDR(-/-) and VDR(-/-)/RXR gamma(-/-) mutant mice. Histological analysis of VDR(-/-)/RXR gamma(-/-) growth plates revealed that development of the hypertrophic chondrocytes was selectively impaired. Thus, our findings indicated that the combined actions of VDR- and RXR gamma-mediated signals are essential for the normal development of growth plate chondrocytes, and raised the possibility that a functionally redundant VDR is present on chondrocytes as a heterodimer with RXR gamma.

Animals↗
PubMed2001

Higher yielding isolation of kinsenoside in Anoectochilus and its antihyperliposis effect.

A higher concentration of kinsenoside, 3-(R)-3-beta-D-glucopyranosyloxybutanolide (1), was detected in the crude drug Anoectochilusformosanus, and A. koshunensis by HPLC analysis. A methylation reaction occurred to give methyl ester (4) when the lactone ring of 1 was cleaved by silica gel catalysis using methanol containing solvent used in the purification step resulting in difficulty to purify 1. To avoid the cleavage reaction, a reversed-phase or silica gel column without methanol was used to give a high yield of 1. In an anti-hyperliposis assay using high-fat diet rats, 1 significantly reduced the weights of body and liver, and also decreased the triglyceride level in the liver compared to those of control rats. On the other hand, the epimer of 1, 3-(S)-3-beta-glucopyranosy-loxybutanolide (2), trivially named goodyeroside A, which was isolated from Goodyera species, had no effect for anti-hyperliposis. In aurothioglucose-induced obese mouse, 1 suppressed the body and liver weight increase, significantly ameliorated the triglyceride level in the liver, and also reduced the deposition of uterine fat-pads.

4-Butyrolactone↗