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Biomedical subjects

K Otsuki

Publications and source records attributed to K Otsuki.

At least 55 records · Page 3Linked to original sources
PubMed1997

Differences in sialic acid-galactose linkages in the chicken egg amnion and allantois influence human influenza virus receptor specificity and variant selection.

Human influenza viruses are more efficiently isolated by inoculating patient samples into the amniotic rather than the allantoic cavity of embryonated chicken eggs. This type of cultivation selects virus variants with mutations around the hemagglutinin (HA) receptor binding site. To understand the molecular basis of these phenomena, we investigated the abundances of sialic acid (SA) linked to galactose (Gal) by the alpha-2,3 linkage (SA alpha2,3Gal) and SA alpha2,6Gal in egg amniotic and allantoic cells and in Madin-Darby canine kidney (MDCK) cells. Using SA-Gal linkage-specific lectins (Maackia amurensis agglutinin specific for SA alpha2,6Gal and Sambucus nigra agglutinin specific for SA alpha2,3Gal), we found SA alpha2,3Gal in both allantoic and amniotic cells and SA alpha2,6Gal in only the amniotic cells. MDCK cells contained both linkages. To investigate how this difference in abundances of SA alpha2,3Gal and SA alpha2,6Gal in allantoic and amniotic cells affects the appearance of host cell variants in eggs, we determined the receptor specificities and HA amino acid sequences of two different patient viruses which were isolated and passaged in the amnion or in the allantois and which were compared with MDCK cell-grown viruses. We found that the viruses maintained high SA alpha2,6Gal specificities when grown in MDCK cells or following up to two amniotic passages; however, further passages in either the amnion or allantois resulted in the acquisition of, or a complete shift to, SA alpha2,3Gal specificity, depending on the virus strain. This change in receptor specificity was accompanied by the appearance of variants in the population with Leu-to-Gln mutations at position 226 in their HA. These findings suggest that lack of SA alpha2,6Gal linkages in the allantois of chicken eggs is a selective pressure for the appearance of host cell variants with altered receptor specificities and amino acid changes at position 226.

Allantois↗
PubMed1997

Enhanced neuropathogenicity of avian influenza A virus by passages through air sac and brain of chicks.

Three-day-old, specific-pathogen-free (SPF) chicks were inoculated with the strains of influenza A/whistling swan/Shimane/ 499/83 (H5N3) via the air sac route. The strains had been passaged through air sacs or air sacs and brains of SPF chicks. Two experiments were undertaken to examine the pathogenicity of these strains and the development of brain lesions based on time-interval changes. In experiment 1, original strain (4e) showed low pathogenicity with mild respiratory signs and zero mortality. Air sac passaged strains (18a and 24a) of 4e demonstrated mortalities of 50% and 67%, respectively, and inoculated chicks showed hemorrhages and necrotic lesions in major organs. Air sac-brain passaged strain (24a5b) of 4e produced 100% mortality and severe nervous signs. Severe circulatory disturbance with multiple foci of necrosis in major organs including the brain was found in chicks inoculated with 24a5b. The 24a5b was analogous to highly pathogenic avian influenza virus in regard to its pathogenicity to chicks. Hence, low pathogenic influenza virus (4e) gradually aggravated its pathogenicity to highly pathogenic virus (24a5b) by air sac and brain passages. In experiment 2, chicks were inoculated with 24a5b, and the earliest histological lesion was the enlargement of the vascular endothelial cells at 18 hr post-inoculation (PI) followed by necrotizing encephalitis at 24 to 48 hr PI. Immunohistological staining revealed avian influenza virus antigen initially in the vascular endothelial cells and then in the astrocytes, neurons and ependyma.

Air Sacs↗
PubMed1997

Identification of pathogenic strains within serogroups of Yersinia pseudotuberculosis and the presence of non-pathogenic strains isolated from animals and the environment.

The existence of apathogenic strains of Yersinia pseudotuberculosis (Yp) has not so far been reported. Recently, the authors characterized new serogroups and a new subgroup in Yp, that is, O9, O10, O12, O13 and O14 and O1c, and the pathogenicity of these new strains was of interest. A total of 137 strains of serogroups O1c, O6, O7, O9, O10, O11, O12, O13 and O14 of Yp were investigated for their pathogenicity in vivo and in vitro. Although catalase activity and the inv gene were detected in all strains except those of groups O13 and O14, only a few strains, from serogroups O6 and O10 caused severe infection in mice. The remaining strains caused no mortality or severe infection even when they grew in limited tissues of infected mice. All the strains of Yp not possessing the virulence plasmid p YV caused no severe infection in mice. It is evident that less pathogenic Yp exists and that not only pathogenic but also less pathogenic Yp organisms exist in the same serogroup.

Animals↗
PubMed1997

Avian influenza A virus induced stunting syndrome-like disease in chicks.

Two-day-old specific-pathogen free chicks were inoculated with type A influenza virus (A/whistling swan/Shimane/499/83 (H5N3) through the air sac. Inoculated chicks showed mild to severe diarrhea and lesions of pancreatitis and atrophy of the pancreas, thymus and bursa of Fabricius. One chick died on each of days 4, 6 and 14 postinoculation (PI). Reduced weight gain was conspicuous from day 22 PI. Positive immunoreaction to the virus antigen was detected in the pancreas, kidneys, liver, lungs and air sacs, and cecal lamina propria. Virus recovery persisted longer in the pancreas. Some of these findings conformed to those of stunting syndrome.

Air Sacs↗
PubMed1997

Release of superoxide anion from polymorphonuclear leukocytes stimulated by rubella viral antigen-antibody complex in vitro.

Using a highly sensitive and specific chemiluminescence (CL) method, we detected the release of superoxide anion (O2-.) from human polymorphonuclear leukocytes (PMNLs) stimulated by rubella viral antigen-antibody complex (VAAC) adsorbed on latex particles. The amount of superoxide anion produced by PMNLs was proportional to the amount of VAAC. Neither rubella virus alone nor antibody alone, adsorbed on latex particles, stimulated production of superoxide anion by PMNLs. It is likely that rubella virus requires the presence of antibody in order to be recognized by PMNLs, and that the superoxide anion is somehow involved in the disease process of rubella.

Antibodies, Viral↗
PubMed1996

Prognosis of hypertrophic cardiomyopathy: assessment by 123I-BMIPP (beta-methyl-p-(123I)iodophenyl pentadecanoic acid) myocardial single photon emission computed tomography.

123I-BMIPP (beta-methyl-iodophenyl pentadecanoic acid) has shown unique properties for potential use in assessing myocardial metabolism. Previous basic and clinical studies demonstrated that the disturbances of myocardial metabolism precede the occurrence of myocardial perfusion abnormalities by using 201Tl in hypertrophic myocardium. The present study was therefore undertaken to determine whether or not 123I-BMIPP myocardial SPECT is useful in predicting the prognosis of hypertrophic cardiomyopathy (HCM) in 65 patients in 6 facilities. There were 33 patients with non-obstructive HCM, 12 with obstructive HCM, 12 with apical HCM and 8 with dilated-phase HCM. Fasted patients at rest received an intravenous injection of 111 MBq of 123I-BMIPP. Twenty to thirty minutes later, myocardial SPECT was carried out. The BMIPP severity score (BMIPP SS) was evaluated semiquantitatively by using representative short axial SPECT images. We followed up the incidence of cardiac events for a mean period of 3.0 +/- 0.6 years. Cardiac events occurred in 13 patients. Of these, 11 developed heart failure and 6 died (4 from heart failure and 2 from sudden death). The BMIPP SS in the dilated-phase HCM was significantly lower than that for the nonsurvivors. The BMIPP SS was particularly high in patients with fatal heart failure. Furthermore, there was a close negative correlation between the BMIPP SS and percent fractional shortening measured by echocardiography (r = -0.49). Finally, the mortality over the three years increased according to the extent of the BMIPP SS. In conclusion, these results indicate that BMIPP SS is useful in evaluating the severity of HCM. We conclude that 123I-BMIPP is a valuable metabolic tracer in predicting the outcome of HCM.

Adult↗
PubMed1996

[Study of components in crude drugs by headspace gas chromatography. II. Components of atractylodes].

Determination of volatile components in essential oils from Atractylodis plants was studied by headspace gas chromatography. The crude drug of 0.20 g with 1.0 ml of water in a capped vial was heated at 130 degrees C for 45 min. Then 0.5 ml of vaporized components were collected by gas tightsillinge, and were applied into the injection port of GC or GC/MS. Consequently we could analyze and confirm the following components; hinesol and beta-eudesmol were found to be contained in Atractylodis Lanceae Rhizoma and atractylon in Atractylodis Rhizoma. beta-Eudesmol was analyzed by headspace gas chromatography, and the obtained calibration curve showed good linearity over the range from 2.5 micrograms to 10.0 mg. The result agreed with those obtained using numerical analyses by the steam distillation method. Atractylodis was found to have a wide variety of components depending on the available sources and on the stored conditions. This method was, therefore, more rapid and simpler determination of essential oils in crude drugs using headspace gas chromatography than those used previously. The method was useful means of the analyses of components in crude drugs such as Atractylodis plants and quality control.

Chromatography, Gas↗
PubMed1996

Demonstration of serum-neutralising antibody to turkey rhinotracheitis virus in serum from chicken flocks in Japan.

Since between 1989 and 1991, broiler, broiler breeder and layer chickens reared in three different prefectures of Japan, Hyogo, Ibaraki, and Miyazaki, were diagnosed clinically as having swollen head syndrome (SHS) these flocks were survey for antibody to turkey rhinotracheitis (TRT) virus using a serum neutralisation (SN) test. TRT-specific SN antibody was found in flocks of chickens in 2 out of the 3 prefectures. Thereafter, particular in the summers of both 1993 and 1994 outbreaks of SHS occurred in almost all areas of major chicken production in Japan. Almost chicken flocks affected by SHS possessed TRT SN antibody. No chicken sera collected between 1972 and 1988 possessed any SN antibody to TRT virus. It is suggested that in Japan, TRT virus is widely prevalent in areas of major poultry production.

Animals↗
PubMed1996

[Recent progress in development of psychotropic drugs (4)--Anticonvulsants: an overview on the mechanisms of action].

Conventional anticonvulsants can be classified into three types according to their mechanisms of action: (1) those which act on voltage-dependent Na+ channels such as phenytoin, (2) those which act on T-type Ca2+ channels such as ethosuximide, and (3) those which enhance GABA receptor-mediated inhibitory neurotransmission such as phenobarbital or valproate. However, recent studies on experimental models of epilepsy have suggested that the neural mechanisms underlying experimental epileptogenesis are based on: (1) increments in cellular excitability through changes in the function of Na(+)- or Ca2+ channels, (2) desinhibition or inhibition failure, and (3) enhancement of excitatory amino acid receptor-mediated excitatory neurotransmission. These findings might help us to understand the recently developed anticonvulsants and vice versa. In this review, newly developed anticonvulsants are categorized according to the neural mechanisms underlying epileptogenesis, particularly actions on excitatory and inhibitory neurotransmission.

Animals↗
PubMed1995

[Epidemiological study of tsutsugamushi disease in Gunma prefecture. A special field study and serotype].

An epidemiologically investigated of invasion of Rickettsia tsutsugamushi, inhabitant of mites and serum sample from patients with Tsutsugamushi disease in Gunma prefecture from 1984 to 1994 was made. Our data clearly indicated that Rickettsia tsutsugamushi was not located but widely spreaded throughout the Prefecture. Mites on rodents, were classified into 4 genus and 12 species and about 15% of them were Leptotrombidium pallidum and Leptotrombidium scuttellare, well known virulent vectors. The highest incidence rate of this disease was observed in the northwest area of the Prefecture from October to December, while a smaller number of patients occurred in other areas and in other months. About fifty percent of the serum samples from the patients were positive to the Karp strain. These results suggest that the major cause of this disease is the Karp strain and the disease could occur potentially in various areas of the Prefecture.

Animals↗
PubMed1995

Distribution of antibodies to influenza A virus in chickens in Japan.

A serological surveillance was carried out to detect antibody against influenza A virus in chicken sera. A total of 8,850 field samples were collected from 47 prefectures in Japan. Initially, all the sera were screened by agar gel immunodiffusion and those sera showing positive reaction were investigated for haemagglutination-inhibition (HI) and neuraminidase-inhibition antibodies against influenza viruses. Only 6 samples had antibodies; 4 sera had antibodies against human subtype H1N1 virus; with HI activity against strain A/PR/34; three sera had strong HI activity to strain A/Tottori/4/87, which by haemagglutination test is closely related to A/Yamagata/120/86. The remaining two chicken sera had antibodies against avian subtypes H10N4 and H3N6 viruses respectively.

Animals↗
PubMed1995

Drug resistance and conjugative R plasmids in Escherichia coli strains isolated from migratory waterfowl.

We evaluated drug resistance and R plasmids of 554 stains of Escherichia coli isolated from feces of migratory watefowl, including whistling swans (Cygnus columbianus), pintails (Anas acuta) and black-tailed gulls (Larus crassirostris) collected from the San-in District, Japan, between each November and March, 1983 to 1984, 1984 to 1985, and 1985 to 1986. Seven antimicrobial agents were tested: dihydrostreptomycin (DSM), kanamycin, spectinomycin, ampicillin (ABPC), oxytetracycline (OTC), chloramphenicol, and sulfadimethoxine (SDMX). Many strains were resistant to several drugs; in particular, all strains were resistant to SDMX. Both multiple drug resistant strains and drug resistance patterns occurred most frequently in strains isolated from whistling swans, followed by black-tailed gulls, and pintails, respectively. Of 233 strains, 128 (55%) carried transmissible R plasmids. The drugs with the largest number of resistance patterns observed were, in descending order, OTC, DSM, ABPC, and SDXM.

Animals↗
PubMed1994

Experimental infection with avian infectious bronchitis virus (Kagoshima-34 strain) in chicks at different ages.

Chicks at 2, 4 or 6 weeks of age were experimentally infected individually with a nephrosis/nephritis-causing avian infectious bronchitis virus (IBV) strain Kagoshima-34. The susceptibility of chicks in each group to the infection was compared, based on the clinical signs, excretion of virus in the faeces and antibody titres in the serum. The results showed that although all chicks appeared to be susceptible to IBV infection, the most severe clinical response was observed following infection at 2-week-old. Likewise, whilst the virus was also recovered from the faeces of all the chicks infected, the duration of viral excretion was longest in the 2-week-old chicks. A high antibody titre was detected at 4 weeks post infection (PI) and was maintained for at least another 16 weeks in the 4- and 6-week-old chicks. In contrast, a low antibody titre was detected only between 8 to 12 weeks PI in the 2-week-old chicks. Thereafter, no antibody was detected despite the presence of clinical signs.

Aging↗
PubMed1994

Comparison of the susceptibility of chicks of different ages to infection with nephrosis/nephritis-causing strain of infectious bronchitis virus.

Two- and 6-week-old chicks were inoculated with the Kagoshima-34 strain of avian infectious bronchitis virus. Serum, bile, Harderian gland, lachrymal fluid, saliva and tracheal washings were collected and their antibody content determined using neutralisation tests. The neutralising antibody (NA) in the serum and bile was detected earlier and in slightly higher concentration in the 6-week-old chicks. Although there was no marked difference in the levels of NA in other body fluids, it was detected earlier in the 6-week-old chicks. In both experiments, the clinical signs were more severe in the 2-week-old chicks. Recovery of virus from the trachea of both ages was not different but virus was recovered for longer in the lungs, kidneys and colon of the 2-week-old chicks. This is the first report wherein IBV-neutralising antibody in the bile is described.

Aging↗
PubMed1994

[Detection of myocardial viability by delayed imaging after 201Tl reinjection].

Recent studies have demonstrated that some underestimation of myocardial viability remained to be not resolved even using reinjection method. So we devised a new technique of reinjection and reimaging, and using this we studied the detectability of myocardial viability in 32 patients of CAD. Exercise imaging (EX) was acquired after initial injection of thallium (111 MBq). Three hours after EX, the second dose thallium (37 MBq) was reinjected, and then the first reinjection image (Re1) was performed. Furthermore, the second reinjection image (Re2) was obtained at 3 hours after the second dose reinjection. SPECT images were divided in basal, mid and apical parts, and totally 13 segments were analyzed by visual scoring (0: severe, 1:moderate, 2:mild hypoperfusion and 3:normal). Twenty-seven (13.4%) of 202 segments of low score (0 to 2) shown in EX were improved in Re2, compared with Re1. Twenty-one (42.0%) of 50 segments of score 0 or 1 shown in Re1 were improved in Re2. These results showed that our devised new method of reimaging 3 hours after the second dose injection was useful to improve in detectability of myocardial viability.

Aged↗