Search PubMed⌕ Search

Biomedical subjects

T Morimoto

Publications and source records attributed to T Morimoto.

At least 829 records · Page 46Linked to original sources
PubMed1975

Development of an attenuated strain for Japanese encephalitis live virus vaccine for porcine use.

To develop Japanese encephalitis live virus vaccine for the prevention of stillbirth in swine, an attempt was made to produce an attenuated virus. Primary bovine kidney cell culture was used to carry out serial passages of a field strain at 30 degrees C for a long time. During these passages cloning was repeated with the character of reproductive capacity at given temperature (rct) and plaque sizes as markers. As a result, an attenuated S- strain was produced successfully. It was rct/37- and rct/40- and formed small-sized plaques. In this strain a marked attenuation was seen in peripheral infectivity to suckling mice and in intracerebral infectivity to adult mice. When inoculated with this strain, newborn piglets manifested no abnormal clinical signs or pathological changes of the brain tissue at all. A minute amount of virus was rarely recovered from some lymph nodes and blood. Little virus was recovered from various organs. No viremia was detected from any piglet more than one month of age inoculated with recovered virus. No infection of the placenta or fetus was recognized in any pregnant sow inoculated with recovered virus. Inoculated sows gave birth to normal young. Furthermore, when mosquitoes of Culex tritaeniorhynchus summorosus were allowed to suck infected blood by the membrane feeding technique, the virus recovered from them showed an infectivity more reduced than the field strain. From these results, it was presumed that the S- strain might be safe enough to be used as live virus vaccine for swine.

Animals↗
PubMed1975

Facilitatory effect of lingual nerve stimulation on masseteric EMG Activities of the cat.

Unitary EMG activities in masseter muscle of decerebrate cats were recorded during repetitive stimulation (20-50 Hz) of the lingual nerve and during vibration. These two kinds of stimuli facilitated EMG activities, whereby their effects could summate. Masseteric EMG response was also obtained during jaw opening phase of the cyclic jaw movement. With the jaw cyclically moved at a widely opened position: motor units discharged even at the jaw closing phase during simultaneous lingual nerve stimulation or during vibration. Based on the results obtained, two possible pathways for lingually induced excitation of masseteric EMG can be speculated on: an excitatory pathway from the lingual nerve to the masseteric motoneurons, secondly a direct pathway to masseteric motoneurons. As facilitation of masseteric EMG was obtained with the threshold lower than that of jaw opening reflex, separate afferent fibers concerning these two reflexes should also be considered.

Animals↗
PubMed1975

Immunization of pigs with the attenuated S- strain of Japanese encephalitis virus.

The attenuated S- strain of Japanese encephalitis virus was produced from a wild strain of this virus by serial cultivation in primary bovine kidney cell cultures at 30 degrees C. Pigs were inoculated with it and examined for ability to produce antibody and protect themselves from infection with a wild strain used for challenge. In pigs inoculated with a single dose of 10(6.5) approximately 10(7.5) TCID50 of the S- strain, the neutralizing antibody titer or hemagglutination-inhibiting antibody (HI) titer increased to 10 approximately 320. An antibody titer exceeding 10 was maintained for 2 approximately 9 weeks. In pigs inoculated twice with 10(6.5) approximately 10(7.0) TCID50 of the S- strain, HI titer increased to 80 approximately 640. In many of these pigs, HI titers of 80 approximately 160 persisted for more than 6 weeks. Pigs inoculated once or twice with 10(7.0) approximately 10(7.5) TCID50 of the S- strain were challenged by inoculation with 10(4.5) approximately 10(5.5) TCID50 of a wild strain and examined for the occurrence of viremia. As a result, an ability to protect from infection was demonstrated in pigs which showed an antibody titer surpassing 10 at the time of challenge. Pregnant sows inoculated with 10(7.0) TCID50 of the S- strain were challenged by inoculation with 10(7.0) TCID50 of a wild strain. Neither death nor infection occurred to any fetus harbored by them. From these results, it is concluded that the S- strain can be used as live virus vaccine for porcine practice.

Animals↗
PubMed1974

Ultrastructural and biochemical studies on the precursor ribosomal particles isolated from rat liver nucleoli.

Sucrose density gradient analyses of pH 5.5 and pH 7.4 extracts from rat liver nucleoli revealed the presence of two broad peaks of approximately 60S and 80S, and 60S and 80-100S, respectively. Ribonucleoprotein (RNP) particles containing precursor ribosomal RNA in these peaks have been characterized by electron microscopy and RNA analyses. Spherical particles only were found in the 60S peak of the pH 5.5 extract, from which 28S RNA and smaller RNA (23S and 18S RNA) exclusively were extracted. In the broad 80S peak of the pH 5.5 extract, about 60% of the particles were spherical while 30% were rodlike. In the RNA species present there were 28S plus smaller RNA (80%) and 35S RNA (20%). The 60Speak of the pH 7.4 extract contained mainly spherical particles (84%), and the RNA species present was mostly 28S plus smaller RNA (89%). In addition to spherical particles (43%), a number of rodlike (31%) and filamentous molecules (26%) were observed in the heavier side of the 80-100S peak of the pH 7.4 extract, from which 45S (14%), 35S (26%), and 28S and smaller RNA (60%) were extracted. Thus the precursor ribosomal particles containing 45S RNA and 35S RNA appear to be filamentous and rodlike molecules, respectively. Folding of loose ribonucleoprotein filaments into compact, spherical, large subparticles may be part of the maturation process of ribosomal large subparticles, in addition to the so-called sequential cleavage of RNA.

Animals↗