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Biomedical subjects

S Tanabe

Publications and source records attributed to S Tanabe.

At least 109 records · Page 6Linked to original sources
PubMed2000

Isomer-specific accumulation and toxic assessment of polychlorinated biphenyls, including coplanar congeners, in cetaceans from the North Pacific and Asian coastal waters.

To elucidate the global distribution and toxicological impacts of polychlorinated biphenyls (PCBs) on cetaceans, the present study determined the concentrations of individual PCB congeners, including toxic non-ortho (IUPAC Nos. 77, 126, 169) and mono-ortho (IUPAC Nos. 105, 118, 156) coplanar congeners, in the blubber of 10 species of adult male odontocetes collected from several locations in the North Pacific Ocean and along coastal waters of Japan, Hong Kong, the Philippines, and India during 1985-1997. Total PCB concentrations in cetaceans from temperate and cold waters were higher than those in cetaceans from tropical regions. Residue levels were found to be the highest in Fraser's dolphins collected off Kii Peninsula, Japan, and hump-backed dolphins from Hong Kong, reflecting serious marine pollution by PCBs in industrialized Asian countries. Penta- and hexa-chlorobiphenyls were the predominant PCB congeners, accounting for about 70% of the total PCBs. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents (TEQs) of non- and mono-ortho coplanar PCBs in the blubber of cetaceans ranged from 36 (in spinner dolphins from the Philippines) to 510 pg/g wet weight (in hump-backed dolphins from Hong Kong). Toxic evaluation of coplanar PCBs using the TEQ concept indicates an greater impact on cetaceans from mid-latitudes. Toxicity contribution of mono-ortho congener IUPAC 118 was prominent in species from high latitude oceans, such as the Bering Sea and the North Pacific, whereas non-ortho congener IUPAC 126 accounted for the highest contribution in cetaceans from lower latitude regions, such as the Philippines and India. The estimated TEQ concentrations in the blubber of some cetacean species, such as northern right whale dolphin and Pacific white-sided dolphin from the northern North Pacific, Dall's porpoise from the Japan Sea, striped dolphin off Sanriku and Fraser's dolphin off Kii Peninsula, Japan, hump-backed dolphin and finless porpoise from Hong Kong, exceeded the levels associated with immunosuppression in harbour seals.

Animals↗
PubMed2000

Toxic assessment of PCBs by the 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent in common cormorant (Phalacrocorax carbo) from Japan.

Common cormorants collected from three colonies and their fish diet were analyzed for PCB congeners and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) were estimated. The highest total PCBs (40 microg/g wet weight) found in adult cormorants from Shinobazu Pond located in Central Tokyo, was sevenfold higher than that from Lake Biwa. IUPAC 153 was the most abundant congener in adults and eggs, whereas IUPAC 28 + 31 was higher in some chicks and exhibited growth-related congeneric enrichment. The estimated metabolic index (MI) for PCB congeners revealed that monoand non-ortho coplanars had higher bioaccumulation in cormorant liver and were expected to cause toxic effects. Among non-ortho coplanars, IUPAC 126 was predominant, and total non-ortho coplanars and TEQs in cormorants were threefold higher in Shinobazu Pond than those from Lake Biwa. The non-ortho IUPAC 126 contributed a higher portion to the total TEQs followed by IUPAC 105 and IUPAC 77. The hepatic IUPAC 169/126 ratio increased significantly with TEQs, implying a potential induction of drug-metabolizing enzymes in Shinobazu Pond cormorants. Based on the available data, PCB contamination in cormorants is enough to pose sublethal effects, especially in Shinobazu Pond and Godaiba Island, Tokyo, Japan. This could be a reason for recently observed high chick and juvenile mortality in those colonies in Tokyo.

Animals↗
PubMed2000

A first-passage-time analysis of the periodically forced noisy leaky integrate-and-fire model.

We present a general method for the analysis of the discharge trains of periodically forced noisy leaky integrate-and-fire neuron models. This approach relies on the iterations of a stochastic phase transition operator that generalizes the phase transition function used for the study of periodically forced deterministic oscillators to noisy systems. The kernel of this operator is defined in terms of the the first passage time probability density function of the Ornstein Uhlenbeck process through a suitable threshold. Numerically, it is computed as the solution of a singular integral equation. It is shown that, for the noisy system, quantities such as the phase distribution (cycle histogram), the interspike interval distribution, the autocorrelation function of the intervals, the autocorrelogram and the power spectrum density of the spike train, as well as the input-output cross-correlation and cross-spectral density can all be computed using the stochastic phase transition operator. A detailed description of the numerical implementation of the method, together with examples, is provided.

Action Potentials↗
PubMed2000

Identification of novel cytochrome P450 1A genes from five marine mammal species.

Marine mammals, being endangered by the chronic exposure of hydrophobic environmental contaminants as an assorting result of global pollution, are especially focused as indicators for organochlorine pollution. The use of contaminant-induced xenobiotic metabolizers, particularly P450 (CYP) 1A, in marine mammals can be effective as potential biomarkers of the contaminant exposure and/or toxic effects. In this study, we identified the first marine mammalian CYPs. Six novel CYP1A cDNA fragments were cloned from the livers of marine mammal species, minke whale (Balaenoptera acutorostrata), dall's porpoise (Phocoenoides dalli), steller sea lion (Eumetopias jubatus), largha seal (Phoca largha), and ribbon seal (Phoca fasciata) by the method of reverse transcription/polymerase chain reaction (RT/PCR); two distinct fragments were from steller sea lion and one fragment each was obtained from the other species. Five of the fragments, one from each species, were classified in the subfamily of CYP1A1, and the other fragment cloned from steller sea lion was designated CYP1A2. Degenerate PCR primers were used to amplify the fragments from liver cDNAs. The deduced amino acid sequences of these fragment CYP1As showed identities ranging from 50.0 to 94.3% with other known vertebrate CYPs in the subfamily of CYP1A, including those from fish, chicken, and terrestrial mammals. The isolated fragments were used to construct a molecular phylogeny, along with other vertebrate CYP1A cDNAs cut down in size to the corresponding region of 265 bp in which those newly determined fragments were cloned. This phylogenetic analysis by the maximum parsimony method using the PHYLIP program suggests two distinct evolutional pathways for aquatic mammalian CYP1As, compatible to a conservative taxonomy. Pinniped genes are clustered together with dog gene, forming a carnivore group, and cetaceans form another branch. Identification of CYP1A genes in marine mammals will be an introductory step to provide new insights into the metabolic or toxicological functions of CYP1As in these animals.

Amino Acid Sequence↗
PubMed2000

Mercury and cadmium in common cormorants (Phalacrocorax carbo).

Mercury (Hg) and cadmium (Cd) in common cormorants (Phalacrocorax carbo) collected in Lake Biwa, Japan and Tokyo, Japan, were investigated to elucidate the biological behaviors of these elements, and to assess exposure to these pollutants of wild, fish-eating birds. Hg and Cd concentrations were highest in the liver and kidneys, respectively. The lowest levels of both elements were observed in chicks. Hg concentrations in all tissues except brain increased significantly with growth from chicks to juveniles (p<0.05, U-test). Cd concentrations in the kidneys and liver also increased significantly during growth from juvenile to adult (p<0.005, U-test). When comparing hepatic Hg and Cd in adult birds between 10 samples from Lake Biwa and nine samples from Tokyo, the Cd concentrations in the Lake Biwa samples (1.4+/-0.37 microg/g dry wt) (mean+/-SD) were significantly higher than those from Tokyo (0.32+/-0.16 microg/g dry wt) (p<0.005, U-test), while no statistically significant difference was found in the Hg concentrations. Possible causes of these differences were discussed in relation to their prey.

Journal Article↗
PubMed2000

Widespread contamination by tris(4-chlorophenyl)methane and tris(4-chlorophenyl)methanol in cetaceans from the North Pacific and Asian coastal waters.

For understanding global distribution, transport and behavior of tris(4-chlorophenyl)methane (TCPMe) and tris(4-chlorophenyl)methanol (TCPMOH), the two newly identified microcontaminants, the present study determined their concentrations and other persistent organochlorines (OCs) in the blubber of nine species of adult male cetaceans collected from various locations in the North Pacific Ocean and coastal waters of some Asian countries, during 1985-97. Concentrations of TCPMe and TCPMOH were found to be highest in northern right whale dolphins, which may be attributable to wide distribution of this species, including some heavily polluted areas such as coastal California. Elevated residue levels of TCPMe and TCPMOH were observed in both off-shore and coastal species, suggesting widespread contamination of these compounds in the marine environment. Higher contamination of TCPMe and TCPMOH was found in cetaceans from temperate and cold waters than those from tropical regions. The latitudinal distribution of TCPMe and TCPMOH in cetaceans from the North Pacific and Asian coastal waters was similar to that of DDTs, suggesting less transportable nature of TCPMe and TCPMOH in the marine environment. Data on the occurrence of TCPMe and TCPMOH further indicated high bioaccumulation potential of these compounds, which was comparable to DDTs. Relative concentrations of TCPMe/TCPMOH in cetaceans were apparently higher than those observed in seals, suggestive of lower metabolic capacity for these compounds in cetaceans than in pinnipeds, which is similar to classic contaminants like polychlorinated biphenyls and DDTs.

Journal Article↗
PubMed2000

Allozymic variation of Hynobius kimurae Dunn (Amphibia, Caudata).

An electrophoretic survey was conducted to examine genetic divergence among 21 populations of a lotic-breeding salamander Hynobius kimurae from Honshu, Japan. Genetically H. kimurae proved to be specifically distinct from H. naevius. Hynobius kimurae is divided genetically into two groups of local populations, and the five populations from the eastern area are genetically distinct from the remaining populations of the central and western areas. Less prominent genetic differentiation was revealed between the western and central populations. Separation of the eastern and central-western groups are discussed in relation to the formation of the Japanese mainland.

Animals↗
PubMed2000

Arsenic accumulation in three species of sea turtles.

Arsenic in the liver, kidney and muscle of three species of sea turtles, e.g., green turtles (Chelonia mydas), loggerhead turtles (Caretta caretta) and hawksbill turtles (Eretmochelys imbricata), were determined using HG-AAS, followed by arsenic speciation analysis using HPLC-ICP-MS. The order of arsenic concentration in tissues was muscle > kidney > liver. Unexpectedly, the arsenic concentrations in the hawksbill turtles feeding mainly on sponges were higher than the two other turtles primarily eating algae and mollusk which accumulate a large amount of arsenic. Especially, the muscles of the hawksbill turtles contained remarkably high arsenic concentrations averaging 153 mg kg(-1) dry weight with the range of 23.1-205 mg kg(-1) (n = 4), even in comparison with the data from other organisms. The arsenic concentrations in the tissues of the green turtles were significantly decreased with standard carapace length as an indicator of growth. In arsenic compounds, arsenobetaine was mostly detected in the tissues of all the turtles. Besides arsenobetaine, a small amount of dimethylarsinic acid was also observed in the hawksbill turtles.

Animals↗
PubMed2000

Detection of female carriers of congenital color-vision deficiencies by visual pigment gene analysis.

PURPOSE: Congenital color-vision deficiencies are frequent among males, 4.7-8.0%, suggesting that female carriers are present at a frequency of 9-15%. The purpose of this study was to determine whether carriers could be detected by analysis of the visual pigment genes. METHODS: DNA from 29 males with congenital color-vision deficiencies, from their mothers, and from 117 randomly-selected females was analyzed. The most upstream genes, the downstream genes, and the most downstream genes in the red/green pigment gene arrays were amplified separately by PCR. Exon 5 of each gene was analyzed by single-strand conformation polymorphisms (SSCP). RESULTS: Analysis of the visual pigment genes suggests that one of the 29 mothers examined is a female protan and two others are carriers of both protan and deutan defects. The remaining 26 mothers were confirmed to be carriers of congenital color-vision deficiencies. Unusual patterns were observed in 15 (13%) of the randomly-selected females; among them, 5 appeared to be protan carriers and at least 4 to be deutan carriers. CONCLUSIONS: Female carriers of congenital color-vision deficiencies can be detected by analysis of the visual pigment genes. Since the proportion of females showing unusual patterns was slightly higher than expected, some must be false-positives and require more detailed examination.

Color Perception↗
PubMed2000

Isolation and characterization of a novel polysaccharide as a possible allergen occurring in wheat flour.

A new polysaccharide with a molecular weight of 5.0 x 10(4) was isolated as a possible wheat allergen from a water-soluble fraction of flour by affinity chromatography and gel filtration. The isolated polysaccharide was found to be a possible wheat allergen, as it bound specifically to IgE antibodies in the sera of patients allergic to the water-soluble fraction of flour. Chemically, the sugar moiety of the polysaccharide consisted of D-glucose and D-mannose with beta-1,4-linkages in a molar ratio of 4.4:1. Since this mannoglucan is thought to be stable in our body, it would act as a remaining allergen to cause a long-lasting allergic reaction to wheat flour.

Allergens↗
PubMed2000

Producing a low ovomucoid egg white preparation by precipitation with aqueous ethanol.

A novel method for producing a low ovomucoid egg white preparation is proposed. Egg white powder (0.5 g) was dissolved in a 10-fold weight of distilled water and adjusted to pH 5, and ethanol was added to the solution at a final concentration of 20% (v/v). The mixture was vigorously stirred and centrifuged. The precipitate was washed three times with 20% ethanol (6.25 ml each), with about 65% of egg white proteins occurring in the precipitate. The use of ELISA demonstrated that 70% of ovomucoid was recovered from the supernatant fraction. However, functionally important proteins such as ovalbumin, ovotransferrin, and lysozyme still remained in the precipitate. These results may be due primarily to the much higher solubility of ovomucoid in this aqueous ethanol. Food quality evaluation showed that high whippability and foam stability were retained in the low ovomucoid preparation as in its material egg white. This product would thus be applicable as a new processed food for ovomucoid-sensitive allergic patients.

Animals↗
PubMed2000

Novel method for producing hypoallergenic wheat flour by enzymatic fragmentation of the constituent allergens and its application to food processing.

A novel method is proposed to produce hypoallergenic wheat flour suitable for patients allergic to wheat. Wheat flour was mixed with a cellulase solution, and the mixture was incubated at 50 degrees C for 1 h to hydrolyze the carbohydrate allergens. The hydrolysate was further incubated with actinase at 40 degrees C for 1 h while gently stirring to decompose the proteinaceous allergens. The product was evaluated for its allergenicity by an enzyme-linked immunosorbent assay, the results of which suggested negative allergenicity in most cases. The product changed to a batter state that was difficult to process by the usual methods. Gelatinization of the starch in the product and the addition of a surfactant were beneficial for food processing.

Allergens↗
PubMed2000

Occurrence of Tris(4-chlorophenyl)methane, tris(4-chlorophenyl)methanol, and some other persistent organochlorines in Japanese human adipose tissue.

Tris(4-chlorophenyl)methane (TCPMe) and tris(4-chlorophenyl)methanol (TCPMOH) are among the most recently identified environmental contaminants. Despite their widespread contamination in the marine environment, human exposure to these compounds remains relatively unknown. We determined the concentrations of TCPMe, TCPMOH, and other persistent organochlorines such as polychlorinated biphenyls (PCBs), DDT and its metabolites, hexachlorocyclohexane isomers, hexachlorobenzene, and chlordane compounds (CHLs) in human adipose tissue from Japan. TCPMe and TCPMOH were detected in all of the adipose samples analyzed; the concentrations ranged from 2.5-21 and 1.1-18 ng/g lipid weight, respectively. Concentrations of TCPMe and TCPMOH in humans were less than those reported in marine mammals, suggesting the possibility of metabolism and elimination of these compounds by humans. Significant correlation between TCPMe and TCPMOH with concentrations of DDT and its metabolites in human adipose tissues suggested that exposure to DDT is the source of TCPMe and TCPMOH in humans. The age- and sex-dependent accumulation of TCPMe and TCPMOH as well as other organochlorines was less pronounced. Results for other organochlorines indicated that recent contamination status of PCBs in human samples from Japan was higher than that in developing countries, whereas DDT contamination is lower. Greater concentrations of CHLs in human adipose tissue from Japan than in those from other countries suggest that continuous monitoring of CHLs in humans in Japan is necessary. To our knowledge, this is the first study on the accumulation of TCPMe and TCPMOH in human adipose tissue.

Adipose Tissue↗
PubMed2000

[Diagnosis of brain tumor with proton MR spectroscopy--the quantification of gliomas compared with normal brain].

We conducted quantification of proton MR spectroscopy (MRS) using water signal as an internal standard, in order to quantify the concentrations of metabolites in normal adult brains and in gliomas in vivo. Single-voxel spectra were acquired using a point-resolved spectroscopic (PRESS) pulse sequence as part of the Probe. P spectroscopy package on a GE Signa Horizon Hispeed LX1.5T scanner (TR/TE/Ave = 3000 msec/30 msec/64). The volume of interest (VOI) varied from 15.0 x 15.0 x 15.0 mm3 to 20.0 x 20.0 x 20.0 mm3 for the brain. The present study included 26 healthy volunteers and 12 patients with gliomas, whose diagnoses were verified by histologic examination. The calculated concentrations of N-acetyl-aspartate (NAA), creatine (Cre) and choline (Cho) in normal hemispheric white matter were 23.66 +/- 1.94 mM (mean +/- SD), 12.97 +/- 1.44 mM, and 4.38 +/- 0.60 mM, respectively. We found they were not necessarily uniform in different parts of the brain, for example, in the pons and basal ganglia. The concentrations of NAA and Cre decreased in all gliomas (p < 0.001). Cho concentration also decreased in the glioma (p < 0.005). The NAA/Cre, NAA/Cho, and Cre/Cho ratios can distinguish normal brain from gliomas, and NAA/Cho ratio can distinguish low-grade astrocytoma from the high-grade group. The results indicate that this noninvasive method offers reasonable estimation of metabolite concentrations in the brain in vivo and therefore is useful in diagnoses of gliomas.

Adult↗
PubMed2000

[A case of tentorial meningioma presented with pure word deafness].

It has been known that an isolation of Wernicke's area from auditory input results in pure word deafness. In this report, a 73-year-old female case with tentorial meningioma suffering from pure word deafness is reported. The patient initially presented with hydrocephalus, and was treated with a ventriculo-peritoneal(V-P) shunt. A year after the V-P shunt, she suffered from a symptom of deafness. On admission, her repetition and auditory comprehension were severely impaired, while reading and visual comprehension were almost normal. Auditory brain stem response(ABR) revealed normal latency between wave I and V, while wave VI and VII was disappeared. Middle latency response(MLR) showed no wave peak. On MRI, tentorial meningioma compressed bilateral medial geniculate bodies, but not auditory radiation or temporal lobe. 99mTc-HMPAO single photon emission computed tomography(SPECT) showed hypoperfusion in the left temporal lobe, considered as a diaschisis resulting from the isolation of left temporal lobe from auditory input via bilateral medial geniculate bodies.

Aged↗
PubMed1999

Molecular cloning of the canine nicotinic acetylcholine receptor alpha-subunit gene and development of the ELISA method to diagnose myasthenia gravis.

We investigated the molecular structure of canine nicotinic acetylcholine receptor (AChR) alpha-subunit gene and developed an enzyme-linked immunosorbent assay (ELISA) as an immunological method to diagnose myasthenia gravis (MG). Canine AChR alpha-subunit cDNA was constructed from mRNA isolated from skeletal muscle of five dogs using the reverse transcriptase-polymerase chain reaction and its molecular structure was determined. The canine AChR alpha-subunit gene had 1371 base pairs encoding 457 amino acids and had a 96.1% homology to the human AChR alpha-subunit gene at the amino acid level. From the results of sequencing the DNA, specific antibodies to the acetylcholine binding domain of the canine AChR alpha-subunit were produced by immunizing rabbits with synthetic oligopeptides (alpha-subunit 183-200 amino acids). The specificity of the rabbit anti-oligopeptide serum was examined by Western blot analysis using an E. coli-expressed AChR alpha-subunit protein and an AChR alpha-subunit protein fraction prepared from canine skeletal muscle as an antigen. An ELISA assay was developed using oligopeptides corresponding to the binding domain to diagnose canine MG; specific antibodies were detected from two dogs with MG, one diabetic dog and two healthy dogs among 25 dogs examined. Further examinations of the ELISA using a large number of samples of clinically MG-positive and MG-negative dogs are needed to establish its usefulness in MG diagnosis.

Acetylcholine↗