PubMed Health⌕ Search

Biomedical subjects

K Otsuki

Publications and source records attributed to K Otsuki.

At least 37 records · Page 2Linked to original sources
PubMed2000

Recognition of N-glycolylneuraminic acid linked to galactose by the alpha2,3 linkage is associated with intestinal replication of influenza A virus in ducks.

The hemagglutinin (HA) of H3 human influenza viruses does not support viral replication in duck intestine despite its avian origin. A Leu-to-Gln mutation at position 226 and a Ser-to-Gly mutation at position 228 in the HA of human A/Udorn/307/72 (H3N2) permit a reassortant virus [human Udorn HA, with all other genes from A/mallard/New York/6750/78 (H2N2)] to replicate in ducks. To understand the molecular basis of this change in host range restriction, we investigated the receptor specificity of duck influenza viruses as well as of human-duck virus reassortants. The results indicate that the recognition of a glycoconjugate moiety possessing N-glycolneuramic acid (NeuGc) linked to galactose by the alpha2,3 linkage (NeuGcalpha2,3Gal) is associated with viral replication in duck intestine. Immunofluorescence assays with NeuGcalpha2,3Gal-specific antiserum detected this moiety primarily on the crypt epithelial cells of duck colon. Such recognition, together with biochemical evidence of NeuGc in crypt cells, correlated exactly with the ability of the virus to replicate in duck colon. These results suggest that recognition of the NeuGcalpha2,3-Gal moiety plays an important role in the enterotropism of avian influenza viruses.

Animals↗
PubMed2000

Risk factors in causing outbreaks of food-borne illness originating in schoollunch facilities in Japan.

We reviewed records of all outbreaks of food-borne illnesses due to schoollunch in Japan from 1987 through 1996 to determine the risk factors causing these outbreaks. Major hazards in 269 outbreaks were Salmonella spp., Campylobacter jejuni, Escherichia coli and Staphylococcus aureus. Foods including uncooked or partially cooked items, salad or egg products presented a high risk in 62 outbreaks with confirmed food sources. Contaminated food items were involved in 29 incidents (46.8%); storage of foods for an extended period before serving in 29 incidents (46.8%), inadequate cooking and cross contamination in 21 incidents (33.9%) each; infected employees in nine incidents (14.5%).

Campylobacter Infections↗
PubMed2000

Salmonella contamination in commercial layer feed in Japan.

A total of 4,418 samples of commercial layer feeds obtained in 1998 were investigated for the presence of salmonellae. A total of 146 strains of salmonellae which consisted of 32 serovars, including 20 strains of Salmonella Enteritidis, were isolated from 143 feed samples.

Animals↗
PubMed2000

Effect of lactoferrin on lipopolysaccharide (LPS) induced preterm delivery in mice.

BACKGROUND: The present study attempted to confirm the preventive effect of lactoferrin on lipopolysaccharide (LPS) induced preterm delivery in mice. METHODS: Female C3H/HeNCrj mice were pair-mated with male Crj: B6D2F1 mice. On day 15 of gestation, a 50 micron/kg intraperitoneal injection of LPS (LPS group) was administered twice with a 3-hour interval between injections (at 2:00 and 5:00 PM). The mice were also given an intraperitoneal injection of lactoferrin (0.2 or 1 mg/200 microl/body) 1 hour prior to each LPS injection) (at 1:00 and 4:00 PM). To determine the effect of LF on plasma IL-6 level, mother mice were sacrificed and blood samples were obtained at 6 hours after the second treatment of LPS. RESULTS: Preterm delivery was induced by LPS in all mice on day 16 of gestation. Lactoferrin administration to LPS-treated mice significantly prolonged (p<0.001) gestation when compared with the LPS group. Plasma levels of IL-6 in the LPS group (1.628+/-115 pg/ml) were significantly higher (p<0.001) than in the untreated group (497+/-39 pg/ml). On the other hand, administration of lactoferrin (1 mg/body) to LPS-treated mice significantly suppressed (p<0.001) IL-6 levels (1.060+/-154 pg/ml). CONCLUSIONS: Lactoferrin exerts a preventive effect on the incidence of preterm delivery in mice via a suppression of plasma IL-6 augmentation by LPS.

Animals↗
PubMed1999

Phorbol ester facilitates apoptosis in murine fibroblasts pretreated by mild ultraviolet radiation.

Although phorbol 12-myristate 13-acetate (PMA) inhibits apoptosis and promotes the growth of some types of cells, it induces apoptosis in other cells. We evaluated the apoptotic effects of PMA on murine fibroblasts (L-929) that had been exposed to ultraviolet-B (UV-B) radiation at 312 nm, which promotes tumor cell growth. Exposure to PMA alone did not induce Fas, Fas-L, or apoptosis. Cells exposed to mild UV-B irradiation (80 J/m(2)) alone exhibited a slight expression of Fas and Fas-L 36 to 48 h after the exposure, and exhibited apoptosis as evidenced by DNA fragmentation 72 h after exposure. The addition of PMA (0.8 x 10(-5) to 3.2 x 10(-5) M) to the medium 24 h after the UV-B exposure markedly and dose-dependently enhanced these cell responses. Confluent untreated cells, cells cocultured with PMA, and cells cocultured with PMA for 24 h after the UV-B exposure consistently expressed mRNAs for wild-type p53, bcl-2, and ICE. Expression of c-myc mRNA was initially observed, but became undetectable in the cells cocultured for 24 h with a high concentration of PMA (3.2 x 10(-5) M) following UV-B exposure. Such cells subsequently exhibited the maximal apoptotic response. We conclude that mild exposure to UV-B altered murine fibroblast cells in such a way as to facilitate their death by apoptosis upon addition of PMA.

Animals↗
PubMed1999

Genotypic characterization of human and environmental isolates of Salmonella choleraesuis subspecies choleraesuis serovar infantis by pulsed-field gel electrophoresis.

To determine the extent of genetic diversity of Salmonella choleraesuis subspecies choleraesuis serovar Infantis and whether environmental isolates were similar or identical to human isolates, a total of 110 isolates from humans, broiler samples, egg production facilities, riverwater, sewage, and chicken meat were analyzed epidemiologically by pulsed-field gel electrophoresis. While the isolates showed 35 distinct pulsed-field profiles, none had the genotype of the human isolates. One pulsed-field profile was shared by 43 (39%) of the 110 isolates. These results indicate that relatively fewer clonal lines of S. serovar Infantis had spread widely while multiple clonal lines, including the strain involved in the outbreak, exist in Western Japan.

Animals↗
PubMed1999

Genetic variation and susceptibilities to protease inhibitors among subtype B and F isolates in Brazil.

The genetic variation of the human immunodeficiency virus type 1 (HIV-1) protease gene (prt) permits the classification of HIV-1 strains into five distinct protease subtypes, which follow the gag subtyping patterns. The susceptibilities of non-B-subtype strains to protease inhibitors (PIs) and other antiretroviral drugs remain largely unknown. Subtype F is the main non-B strain contributing to the Brazilian epidemic, accounting for 15 to 20% of these infections. In this work, we report the findings on 81 isolates from PI-naive Brazilian patients collected between 1993 and 1997. In addition, the relevant PI resistance mutations and their phenotypes were determined in vitro for 15 of these patients (B = 9 and F = 6). Among these, the subtype F samples evidenced high sensitivities in vitro to ritonavir and indinavir, with MICs at which 50 and 90% of the isolates are inhibited similar to those of both the Brazilian and the U.S. subtype B isolates. Analysis of the 81 Brazilian prt sequences demonstrated that the subtype F consensus sequence differs from the U.S. and Brazilian subtype B consensus in eight positions (I15V, E35D, M36I, R41K, R57K, Q61N, L63P, and L89M). The frequency of critical PI resistance substitutions (amino acid changes D30N, V82A/F/T, I84V, N88D, and L90M) among Brazilian isolates is very low (mean, 2.5%), and the associated secondary substitutions (amino acid positions 10L, 20K, 36M, 46M, 48G, 54I, 63P, 71A, and 77A) are infrequent. These observations document the relative rarity of resistance to PIs in the treatment of patients infected with HIV-1 subtype F in South America.

Amino Acid Sequence↗
PubMed1999

Epidemiological analysis of Salmonella enteritidis from human outbreaks by pulsed-field gel electrophoresis.

To determine the extent of genetic diversity among isolates of Salmonella enteritidis obtained from outbreaks in Fukuoka Prefecture, Japan, from 1989 to 1994, we analyzed a total of 55 isolates of S. enteritidis obtained from 13 distinct outbreaks with pulsed-field gel electrophoresis. These isolates showed three different patterns in pulsed-field profile with Bln I digestion. The groups A, B and C consisted of three outbreaks isolates (Dice coefficient, F = 1), of seven outbreaks (F = 0.56-0.94) and of three outbreaks (F = 0.65-0.78), respectively. This result suggests that a few limited clonal lines of S. enteritidis were successively causing outbreaks in this area from 1989 to 1994.

Animals↗
PubMed1999

Differences in receptor specificity between Newcastle disease viruses originating from chickens and waterfowl.

We compared the receptor specificity of Newcastle disease viruses from a variety of avian species, including chickens and wild waterfowl, using hemagglutination tests with erythrocytes from different animal species. All isolates from wild waterfowl agglutinated horse erythrocytes, while the chicken isolates did not. The results showed that the receptor specificity of Newcastle disease viruses is different, depending on the avian species from which the viruses are isolated.

Animals↗
PubMed1999

Receptor specificity of influenza A viruses from sea mammals correlates with lung sialyloligosaccharides in these animals.

The distribution of specific receptors on target organs is a major factor in the host range restriction of influenza A viruses. To assess the correlation between host receptors and the receptor specificity of influenza A viruses from sea mammals, we examined the receptors for influenza A virus in seal and whale lungs. A binding assay using two sialyloligosaccharide (SAalpha2,3Gal and SAalpha2,6Gal)-specific lectins showed that SAalpha2,3Gal, but not SAalpha2,6Gal, was found in both seal and whale lungs. Correspondingly, seal and whale influenza viruses preferentially recognized SAalpha2,3Gal, but not SAalpha2,6Gal. These results indicate that sialyloligosaccharides present at the replication site of influenza A viruses correlate with the receptor recognition of the viruses isolated from sea mammals.

Animals↗
PubMed1999

Replacement of internal protein genes, with the exception of the matrix, in equine 1 viruses by equine 2 influenza virus genes during evolution in nature.

To establish the evolutionary association between the equine 1 H7 HA and M genes, phylogenetic analyses of the six internal gene segments of equine 1 influenza viruses (H7N7 subtype) were performed using partial nucleotide sequences. The results demonstrated that five internal genes (PBI, PB2, PA, NP and NS) of equine 1 viruses isolated after 1964 were replaced by those of equine 2 H3N8 viruses. However, the M gene was maintained during the evolution of these equine 1 viruses. These findings suggest a functional association between equine H7 HA and M gene products, most likely M2 protein.

Animals↗
PubMed1998

Evidence supporting the activity of 2'-C-cyano-2'-deoxy-1-beta-D-arabino-pentafuranosylcytosine as a terminator in enzymatic DNA-chain elongation.

To investigate the stability of 2'-C-cyano-2'-deoxy-1-beta-D-arabino-pentafuranosylcytosine 3'-phosphoric acid, its thymidine ester was prepared via the phosphoramidite method using allyl protection for the phosphate function. This ester is stable under acidic conditions but extremely labile under basic conditions, decomposing with a cleavage of the internucleotide bond even at pH 7.3.

Antineoplastic Agents↗
PubMed1998

Lactoferrin and interleukin-6 interaction in amniotic infection.

Lactoferrin (Lf) has been found in most biological fluids including amniotic fluid and cervical mucoids in pregnant women, and released from neutrophils in response to the inflammation. As Lf possesses antimicrobial properties, it is widely considered to be an important component of the host defence against microbial infections. It is known that premature labor is caused by amniotic infection with the increase of prostaglandin production. High concentration of the inflammatory cytokines: interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) in the amniotic fluid has been known. However, changes of Lf in amniotic fluid with infection has not been reported. In the present study, Lf concentrations in amniotic fluid were measured under the intra-uterine infections state and the biological significance of Lf was investigated. The effects of Lf on the IL-6 and IL-6mRNA production in cultured amnion cells were also investigated. The concentrations of Lf and IL-6 in amniotic fluid with CAM were 8.76 +/- 0.65 micrograms/ml and 6.92 +/- 4.88 ng/ml (n = 28) respectively and both were significantly higher (p < 0.01) than those without CAM [0.86 +/- 0.81 microgram/ml and 0.34 +/- 0.25 ng/ml (n = 31)]. Significant positive correlation (r = 0.91, p < 0.01) between Lf and IL-6 levels in amniotic fluid was found. IL-6 production induced by lipopolysaccharide (LPS) (100 ng/ml) in cultured amnion cells was significantly inhibited (p < 0.05) under the physiological concentration of Lf in amnion. Total RNA was extracted from the amniotic cells by guianizine solution. RT-PCR procedure and product analysis were performed from one microgram aliquote of total RNA. beta-actin was used as an international standard and c-DNA samples were followed by 30 cycles of PCR. RT-PCR product of IL-6 mRNA was detected by Southern hybridization. Expression of IL-6 mRNA was inhibited by the addition of Lf. From the results, the possibility that Lf might suppress amniotic IL-6 production under the condition of amniotic infection is suggested. It is also suggested that Lf might act as self defence mechanism from intra-uterine infection.

Amnion↗
PubMed1998

Effects of lamotrigine and conventional antiepileptic drugs on amygdala- and hippocampal-kindled seizures in rats.

We investigated the anticonvulsant and adverse behavioral effects of lamotrigine (LTG), a novel antiepileptic drug (AED), as well as other conventional AEDs on kindled seizures in rats. We also applied an anticonvulsive dose of LTG in vivo to rats in which the hippocampus had been subjected to long-term potentiation (LTP). LTG potently attenuated limbic-kindled seizures in a dose-dependent fashion, at doses at which animals showed no adverse behavioral effects. LTG was effective in preventing kindled seizures for up to 24 h after a single i.p. administration. The anticonvulsant effects of LTG were reversed when the stimulus current was raised to two or three times the generalized seizure-triggering threshold. Among the AEDs examined, valproate and LTG were the only drugs that engendered a potent anticonvulsant effect without concomitant adverse behavioral effects. Although all of the other AEDs exhibited anticonvulsant effects with various potencies, they produced adverse effects such as sedation or motor ataxia. Furthermore, an anticonvulsant dose of LTG did not affect either the induction or maintenance of tetanus-induced LTP in the hippocampus. These results indicate that LTG potently suppresses limbic-kindled seizures by raising the seizure triggering-threshold in the kindling focus at doses that do not affect LTP in the hippocampus.

Amygdala↗
PubMed1998

Cloacal inoculation with the Connecticut strain of avian infectious bronchitis virus: an attempt to produce nephropathogenic virus by in vivo passage using cloacal inoculation.

Avian infectious bronchitis virus (IBV) strain Connecticut A-5968 isolated from respiratory tissue of chickens in USA in the 1960s, is considered as representative of respiratory disease causing IBV strains. Specific pathogen free chicks inoculated with the strain via the cloaca replicated the virus more rapidly in their kidneys than did chicks inoculated with the same virus intratracheally. Virus passaged thirteen-times via the cloaca caused stronger nephrotropism and nephropathogenicity than the parent virus. It is suggested that cloacal inoculation of IBV provides new and interesting information concerning the mechanisms of nephropathogenicity of IBV which has became increasingly important worldwide during the last ten years.

Animals↗
PubMed1998

Encephalitis in mice inoculated intranasally with an influenza virus strain originated from a water bird.

Five-week-old ddY mice were inoculated intranasally with a low virulent (4e) or highly virulent (24a5b) avian influenza virus strain originated from a water bird. None of mice in the 4e group showed clinical signs and brain lesions. Of the 24a5b group, two mice died and one mouse was killed at a moribund state at day 7 post-inoculation (PI). Four mice of the 24a5b group necropsied at day 5 or 7 PI had mild to severe encephalitis in the brain stem and the cerebellar white matter. Influenza virus antigen was detected in neurons, glial cells and vascular endothelium in the lesions. The distribution of the lesions seems to indicate the transneuronal invasion of the virus via cranial nerve fibers into the brain.

Animals↗
PubMed1997

Characteristics and pathogenicity of non-melibiose-fermenting strains of Yersinia pseudotuberculosis O3.

The biological properties of non-melibiose-fermenting (NMF) strains of Yersinia pseudotuberculosis O3 were investigated. These strains were clearly distinguished from representative melibiose-fermenting (MF) strains of Y. pseudotuberculosis O3 by their pathogenicity in mice, sensitivity to some phages, production of catalase, restriction endonuclease analysis of virulence plasmid DNA with BamHI, detection of specific yersinia outer-membrane proteins with SDS-PAGE, antigenicity of the outer-membrane proteins and neutrophil resistance to phagocytosis. The pathogenicity of NMF strains was clearly less than that of MF strains. In addition, the resistance of NMF strains to phagocytosis and catalase activity was evidently weaker than that of MF strains. These results suggested that the difference of pathogenicity was due to the ability of catalase production. Although the relationship between the above characteristics and melibiose-fermentation was not analysed, the pathogenicity of Y. pseudotuberculosis O3 strains can probably be predicted by testing melibiose-fermentation and catalase production.

Animals↗