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Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 109 records · Page 6Linked to original sources
PubMed2001

Seasonal distribution of enteropathogens detected from diarrheal stool and water samples collected in Kathmandu, Nepal.

A total of 334 diarrheal fecal samples (from 210 males and 124 females) collected in Kathmandu, Nepal, were studied for various kinds of enteropathogens. Overall, 33% (111/334) fecal samples were positive for one or more enteropathogens. There was no difference in detection rates between males and females. Enteropathogen detection rates in summer, winter, spring, and autumn were 61% (40/66), 52% (45/87), 31% (25/81), and 25% (25/100), respectively. Altogether eight species of bacteria, three genera of viruses, and five species of protozoan parasites were detected with considerable seasonal variations. Among the bacterial isolates, enteropathogenic Escherichia coli topped the list followed by Vibrio sp. Only one sample had Shigella (S. sonnei). Rotavirus type A was the most frequently detected among the enteric viruses, followed by human enterovirus and human adenovirus, respectively. Among the enteric protozoan parasites, Giardia intestinalis was the most frequently detected followed by Cryptosporidium parvum. Detection of bacterial and protozoan pathogens showed a slightly high tendency in the summer season compared with that in the other seasons (p>0.05), whereas the detection of viruses was significantly high in the winter season (p<0.05). Of the total 57 water samples, 43 (75%) showed one or more bacterial species out of which 51% (22/43) were E. coli. Among the E. coli isolates, 68% were EPEC. Enterohemorrhagic E. coli (O157) was not detected.

Adolescent↗
PubMed2000

Chondrocyte extracellular matrix synthesis and turnover are influenced by static compression in a new alginate disk culture system.

The goal of this study was to examine the effects of mechanical compression on chondrocyte biosynthesis of extracellular matrix (ECM) components during culture in a new alginate disk culture system. Specifically, we have examined chondrocyte biosynthesis rates, and the structure of aggrecan core protein species present in the cell-associated matrix (CM), in the further removed matrix (FRM) and in the surrounding culture medium. In this alginate disk culture system, chondrocytes can be subjected to mechanical deformations similar to those experienced in vivo. Our results show that over an 8-week culture period, chondrocytes synthesize a functional ECM and can respond to mechanical forces similarly to chondrocytes maintained in native cartilage. In the alginate disk system, static compression was shown to decrease and dynamic compression to increase synthesis of aggrecan of bovine chondrocytes. Western blot analysis of the core proteins of aggrecan molecules identified a number of different species that were present in different relative amounts in the CM, FRM, and medium. Over 21 days of culture, the predominant form of aggrecan found in the ECM was a full-length link-stabilized species. In addition, our data show that the application of 40 h of static compression caused an increase in the proportion of newly synthesized aggrecan molecules released into the medium. However, this was not accompanied by a significant change in the size and composition of aggrecan and aggrecan fragments in the different compartments, suggesting that mechanical compression did not alter the catabolic pathways. Together, these data show that chondrocyte function is maintained in an alginate disk culture system and that this culture system is a useful model to examine chondrocyte ECM assembly and some aspects of catabolism normally found in vivo.

Aggrecans↗
PubMed2000

Primary structure and functional characterization of bilitoxin-1, a novel dimeric P-II snake venom metalloproteinase from Agkistrodon bilineatus venom.

The amino acid sequence of the hemorrhagic toxin, bilitoxin-1, isolated from the venom of Agkistrodon bilineatus was determined by the Edman sequencing procedure of peptides derived from digests utilizing cyanogen bromide, clostripain, lysyl endopeptidase, and Staphylococcus aureus V8 protease. A molecular mass of 80,000 Da was observed in the nonreduced state and 48,000 Da was observed in the reduced state, as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Each subunit consists of 291 amino acid residues and has a calculated molecular mass of 32,276 Da. The toxin contains fucose, galactosamine, glucosamine, galactose, mannose, and N-acetylneuraminic acid and three N-linked glycosylation consensus sites. Hydrazinolysis and ESI mass spectrometry revealed that asparagine was the carboxyl-terminal amino acid. The disintegrin-like domain of bilitoxin-1 lacks the RGD cell-binding sequence, which is substituted by the MGD sequence. Under certain conditions, the disintegrin domain is autoproteolytically processed from the native protein. Studies with the bilitoxin disintegrin demonstrated that it lacks platelet aggregation inhibitory activity, probably reflecting the substitution of RGD by MGD. The hemorrhagic activity of the asialobilitoxin-1 was only 25% of bilitoxin-1, while proteolytic activity was unaffected. The three-dimensional structure of this toxin was modeled and was shown to likely possess a structure similar to that of adamalysin II (Gomis-Rüth et al., EMBO J. 12, 151-157 (1993)) and the disintegrin kistrin (Adler et al., Biochemistry 32, 282-289 (1993)). In summary, here we report the first primary structure of a dimeric, P-II snake venom metalloproteinase and the biological role of bilitoxin-1 glycosylation and the disintegrin domain.

Agkistrodon↗
PubMed2000

IgE-reactivity to major Japanese cedar (Cryptomeria japonica) pollen allergens (Cry j 1 and Cry j 2) by ELISA in dogs with atopic dermatitis.

The present study investigated IgE-reactivity to two major Japanese cedar (Cryptomeria japonica, C. japonica) pollen allergens (Cry j 1 and Cry j 2) in dogs with atopic dermatitis by use of a fluorometric ELISA. The serum samples from 27 dogs that showed IgE-sensitivity to crude C. japonica pollen allergen by ELISA were tested for specific IgE to the two major allergens. All 27 dogs had anti-Cry j 1 IgE, and 10 (37%) had anti-Cry j 2 IgE. Inhibition of binding of dog specific IgE to crude C. japonica pollen allergen was carried out by addition of Cry j 1. When serum samples containing anti-Cry j 1 IgE but no anti-Cry j 2 IgE were incubated with Cry j 1, specific IgE binding to crude C. japonica pollen allergen was almost abolished. These findings suggest that Cry j 1 is a major allergen in dogs.

Animals↗
PubMed2000

Amplification and over-expression of the AIB1 nuclear receptor co-activator gene in primary gastric cancers.

Our analysis of chromosomal aberrations in primary gastric cancers using comparative genomic hybridization has revealed novel, high and frequent copy number increases in the long arm of chromosome 20, indicating that this region contains novel amplified genes involved in gastric cancer progression. AIB1, a member of the steroid receptor co-activator-1 family, has been cloned on 20q12 as a candidate target gene for this amplification in human breast cancers. In this study, we examined the numbers of AIB1 copies as well as their expression and relation to clinico-pathological features in 72 primary gastric cancers. AIB1 amplification was observed in 7% and over-expression in 40% of the specimens. AIB1 amplification always coincided with its over-expression, but several cases showed AIB1 over-expression without amplification, suggesting that expression of AIB1 is regulated not only by gene amplification but also by other mechanisms, such as transcriptional activation, in human gastric cancer. Gastric cancers with AIB1 amplification showed extensive lymph node metastases, liver metastases and poorer prognosis compared to those without amplification. Our results suggest that amplification and over-expression of AIB1 are likely to increase the number of malignant phenotypes of gastric cancers and that it can be expected to be useful as a marker of poor prognosis.

Adult↗
PubMed2000

Pairing of oligosaccharides in the Fc region of immunoglobulin G.

The Fc portion of immunoglobulin G (IgG) expresses paired oligosaccharides with microheterogeneities, which are associated with efficiencies of effector functions and with pathological states. A comparison of electrospray ionization mass spectrometry data obtained using a variety of Fc fragments derived from human and mouse IgG that do and do not retain the inter-chain disulfide bridge(s) revealed that (1) the Fc portion can be asymmetric as well as symmetric with respect to glycosylation and (2) the ratios of the individual glycoforms are different from what is expected from the random pairing.

Animals↗
PubMed2000

Positive reactions to common allergens in 42 atopic dogs in Japan.

Clinically important allergens for the diagnosis and treatment of atopic dermatitis vary geographically. In order to identify the most prevalent allergens in atopic dogs in Japan, 42 dogs with a clinical diagnosis of atopy were tested using both in vivo (intradermal skin test (IDST)) and in vitro (antigen-specific IgE assay) allergy tests. Allergens used for IDST included 26 allergen extracts from eight allergen groups: trees, weeds, grasses, house dust mites (HDM), molds, foods, epithelia, and arthropods. Immunodot assay was used to measure antigen-specific IgE against 24 allergens from these eight groups and against fish such as cod and sole. In the 42 dogs, the most common positive allergen reaction was to HDM on both IDST (29/42 dogs or 69%) and in vitro testing (23/42 or 54.8%). The second most frequent positive allergen reaction was to Japanese cedar pollen (21/42 or 50.0% for IDST and 7/42 or 16.7% for in vitro testing). In both tests, less than 20% of dogs had positive reactions to molds or foods. Positive reactions to cat epithelia were frequently found on IDST, but rarely found on in vitro testing. Agreement between the two tests was found in 26 instances: HDM (21 dogs), Japanese cedar pollen (five dogs) and wheat (one dog). In this study, the two most common allergens involved in atopic dermatitis in dogs in Japan were HDM and Japanese cedar pollen.

Allergens↗
PubMed2000

N-Glycan structures of an osteopontin from human bone.

N-Glycan structures of osteopontin (a bone matrix protein) from human bone (lumbar vertabrate) are reported in detail. Asn-linked glycan portion was released from 100 microg of osteopontin by digestion with glycoamidase A (from sweet almond), and the reducing ends of the N-glycans were reductively aminated with 2-aminopyridine. The derivatized N-glycans were separated and structurally identified by a multidimensional mapping technique on HPLC columns. Two major N-glycan structures were also confirmed by mass spectrometry. The proposed structures are shown below. The result should permit future comparison with the N-glycan structures of osteopontins obtained from other sources (kidney tissues, macrophages, urinary stones, human milk, etc.).

Aminopyridines↗
PubMed2000

Differential effects of interleukin-1 on hyaluronan and proteoglycan metabolism in two compartments of the matrix formed by articular chondrocytes maintained in alginate.

Phenotypically stable young adult bovine articular chondrocytes suspended in beads of alginate gel were first cultured for 5 days, using daily changes of medium containing 10% fetal bovine serum and supplements. The cells in the beads were then maintained in culture for a further 3 days in the presence or absence of interleukin-1alpha at 1 ng/ml in the daily change of medium. The exposure to interleukin-1alpha caused the incorporation of (35)S-sulfate into the predominant cartilage proteoglycan, aggrecan, to decrease by approximately 60%. In addition, proteoglycans that had accumulated into the cell-associated matrix during the first 5 days of culture in the absence of interleukin-1alpha moved into the matrix further removed from the cells and from there into the medium. In contrast, the exposure to interleukin-1alpha was found to markedly promote the rate of synthesis of hyaluronan, especially during the first 24 h. Over the 3 days of culture in the presence of interleukin-1alpha, a large proportion of the newly synthesized hyaluronan molecules, as well as those that had previously become residents of the cell-associated matrix, moved out of this compartment and appeared to become permanent residents of the further removed matrix. These results demonstrate that exposure of young adult articular chondrocytes to interleukin-1alpha has profound effects on the metabolism of hyaluronan, a molecule that plays a critical role in the retention of proteoglycan molecules in the matrix. Importantly, the results suggest that exposure of chondrocytes to interleukin-1 in inflamed joints, such as occurs in rheumatoid arthritis, leads to the rapid loss of coordination of the synthesis of aggrecan and hyaluronan, two of the critical constituents of the proteoglycan aggregate. In addition, we present evidence that these interleukin-1-induced effects differentially alter the metabolism of hyaluronan in the metabolically active cell-associated matrix and the metabolically inactive matrix further removed from the chondrocytes.

Aggrecans↗
PubMed2000

Characterization of complex chromosomal abnormalities in B-cell lymphoma by a combined spectral karyotyping (SKY) analysis and fluorescence in situ hybridization (FISH) using a 14q telomere probe.

We report a case of non-Hodgkin's lymphoma of unknown origin with invasion into bone marrow and brain. This case showed complex chromosomal abnormalities, including five clonal marker chromosomes (mar) and four additional materials of unknown origin (add) that could not be identified by means of conventional G-banding. Spectral karyotyping (SKY) analysis could not only determine the origin and organization of all thus far unidentified structural chromosomal abnormalities but also detect two cryptic unbalanced translocations, which had been erroneously considered to be normal on the basis of G-banding analysis, and correct one abnormality misidentified by G banding. Among these abnormalities, we identified the new partner site of the 14q32 translocation, 22q13, and the jumping translocations involving 2p23 as a new donor chromosome. Furthermore, by using fluorescence in situ hybridization (FISH) with the probes specific for the 14q telomere, we could identify the unbalanced translocation of t(3;14)(q27;q32), which had been erroneously considered to be normal chromosome 3 on the basis of not only G-banding but also of SKY analysis. This translocation is one of the most frequent chromosomal abnormalities in B-cell lymphoma, especially diffuse large cell lymphoma. After SKY and FISH analysis, the original descriptions in the G-band karyotype were modified for a total of 13 chromosomes. The combination of SKY and FISH using the 14q telomere probe was therefore considered very useful for the characterization of complex cytogenetic cases in B-cell lymphoma.

Chromosome Aberrations↗
PubMed2000

Sex-related differences in the muscarinic acetylcholinergic receptor in the healthy human brain--a positron emission tomography study.

We evaluated the sex-related differences in the decline of the cerebral muscarinic acetylcholinergic receptor (mACh-R) due to aging by using 11C-N-methyl-4-piperidyl benzilate (11C-NMPB) and positron emission tomography (PET). The subjects consisted of 37 (20 males and 17 females) healthy volunteers. The 11C-NMPB uptake was evaluated by the ratio method (regional 11C-NMPB uptake/Cerebellar 11C-NMPB uptake; rNMPB ratio). The correlation between sex, aging, and the rNMPB ratio in normal aging was evaluated by a multiple regression analysis. The rNMPB ratio was higher in females than in males throughout the entire cerebral region (p < 0.01-p < 0.0001) and the rNMPB ratio might thus possibly decline with age more rapidly in females. Our study therefore revealed the existence of sex-related differences in the cerebral mACh-R.

Adult↗
PubMed2000

Biodistribution and breast tumor uptake of 16alpha-[18F]-fluoro-17beta-estradiol in rat.

To evaluate the usefulness of 16alpha-[18F]-fluoro-17beta-estradiol (FES) for the assessment of estrogen receptor (ER), we examined the tissue distribution and kinetics of FES in immature female Sprague-Dawley rats and then examined FES uptake in rat breast tumors induced by 7,12-dimethylbenz(a) anthracene (DMBA). The FES uptake by the uterus, an ER-rich tissue, was highly selective and it was 3.34 +/- 0.79%ID/g at 60 minutes and 1.57 +/- 0.57%ID/g at 120 minutes after injection. The FES uptakes in ER-negative tissues were 0.12 +/- 0.05%ID/g or less and 0.05 +/- 0.03%ID/g or less, respectively. Coadministration of unlabeled beta-estradiol showed marked depression of uterine FES uptake. The FES uptake by rat breast tumors was 0.14 +/- 0.06%ID/g at 60 min and 0.12 +/- 0.09%ID/g at 120 min. The FES uptake by rat breast tumors correlated with the ER concentration (r = 0.45, p < 0.05). In conclusion, these results suggest that the FES uptake by tissue is mainly ER mediated and FES is thus useful for detecting ER positive breast tumors.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2000

Genetic linkage analysis of X-ray hypersensitivity in the LEC mutant rat.

The LEC rat has been reported to exhibit X-ray hypersensitivity and deficiency in DNA double-strand break (DSB) repair. The present study was performed to map the locus responsible for this phenotype, the xhs (X-ray hypersensitivity), as the first step in identifying the responsible gene. Analysis of the progeny of (BN x LEC)F(1) x LEC backcrosses indicated that the X-ray hypersensitive phenotype was controlled by multiple genetic loci in contrast to the results reported previously. Quantitative trait loci (QTL) linkage analysis revealed two responsible loci located on Chromosomes (Chr) 4 and 1. QTL on Chr 4 exhibited very strong linkage to the X-ray hypersensitive phenotype, while QTL on Chr 1 showed weak linkage. The Rad52 locus, mutation of which results in hypersensitivity to ionizing radiation and impairment of DNA DSB repair in yeast, was reported to be located on the synteneic regions of mouse Chr 6 and human Chr 12. However, mapping of the rat Rad52 locus indicated that it was located 23 cM distal to the QTL on Chr 4. Furthermore, none of the radio-sensitivity-related loci mapped previously in the rat chromosome were identical to the QTL on Chrs 4 and 1 in the LEC rat. Thus, it seems that X-ray hypersensitivity in the LEC rat is caused by mutation(s) in as-yet-undefined genes.

Animals↗
PubMed2000

Somatic embryogenesis induced by the simple application of abscisic acid to carrot (Daucus carota L.) seedlings in culture.

Seedlings of carrot (Daucus carota L. cv. Red Cored Chantenay) formed somatic embryos when cultured on medium containing abscisic acid (ABA) as the sole source of growth regulator. The number of embryos per number of seedlings changed depending on the concentration of ABA added to the medium, with a maximum embryo number at 1 x 10(-4) M ABA. Seedling age was critical for response to exogenous ABA; no seedling with a hypocotyl longer than 3.0 cm was able to form an embryo. Removal of shoot apices from seedlings completely inhibited the embryogenesis induced by application of exogenous ABA, suggesting that the action of ABA requires some substance(s) that is translocated basipetally from shoot apices through hypocotyls. Histologically, somatic embryos shared common epidermal cells and differentiated not through the formation of embryogenic cell clumps, but directly from epidermal cells. These morphological traits are distinct from those of embryogenesis via formation of embryogenic cell clumps, which has been found in embryogenic carrot cultures established using 2,4-dichlorophenoxyacetic acid or other auxins. These results suggest that ABA acts as a signal substance in stress-induced carrot seedling somatic embryogenesis.

Abscisic Acid↗
PubMed2000

Recent developments in imaging diagnostics for HCC: CT arteriography and CT arterioportography evaluation of vascular changes in premalignant and malignant hepatic nodules.

We analyzed the hemodynamic properties and vascular supply changes in relation to the carcinogenesis of hepatocellular carcinoma (HCC), selecting 18 premalignant and malignant nodules less than 3 cm diameter (from 14 patients) for our study. The computed tomographic (CT) arteriography and CT arterioportography (CTAP) findings for these nodules were correlated with the histopathologic findings. The ratios of all microscopically counted arteries (normal hepatic and abnormal arteries), normal hepatic arteries, and portal veins in each nodule to those in the surrounding liver were calculated. Well differentiated lesions had low attenuation on CT arteriography and isoattenuation on CTAP. Moderately-to-poorly differentiated lesions had high attenuation on CT arteriography and low attenuation on CTAP. In well differentiated lesions, the ratios of all arteries, normal hepatic arteries, and portal veins were 1.17+/-0.10, 0.66+/-0.12, and 0.80+/-0.10, respectively. In moderately-to-poorly differentiated lesions, the ratios were 2.64+/-0.23, 0.09+/-0.03, and 0.07+/-0.03, respectively. We concluded that blood flow does not parallel the actual number of arteries seen on the histological examination of tumors. In well differentiated lesions, the combination of normal hepatic arterial degeneration and preserved portal veins results in low attenuation on CT arteriography and isoattenuation on CTAP. In advanced HCC, the combination of neoplastic (abnormal) arterial development by angiogenesis and obliteration of portal veins results in high attenuation on CTA and low attenuation on CTAP. These findings are characteristic of early and advanced stage HCC, and may reflect a combination of sequential changes in their hemodynamic states.

Aged↗
PubMed2000

Fulicin regulates the female reproductive organs of the snail, Achatina fulica.

Fulicin is a D-amino acid-containing neuropeptide that has been thought to control male copulatory behavior in the land snail, Achatina fulica. In the present study, we demonstrated that the vagina and the oviduct of Achatina were densely innervated by fulicin-like immunoreactive neuronal fibers. We confirmed that fulicin was actually present in the vagina by mass spectrometry. Furthermore, fulicin showed a profound excitatory effect on contractions of the vagina and the oviduct. These results suggest that fulicin controls female egg-laying behavior as an excitatory neuropeptide regulating the female reproductive organs of the snail.

Animals↗