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Biomedical subjects

K Fukai

Publications and source records attributed to K Fukai.

At least 145 records · Page 8Linked to original sources

A report on the pathology of type A botulism.

An autopsy case of type A botulism, a sacrifice during the first outbreak in Japan, was presented. The patient exhibited typical neuromuscular symptoms and died on the 8th day from the onset of illness. Type A Clostridium botulinum was demonstrated from the stools and the toxin from the blood serum during the course of disease. The infection source of botulinus bacilli, however, was not clarified. The autopsy diagnoses were made as follows; 1) type A botulism, 2) bronchopneumonia, 3) respirator brain, 4) congestion, 5) hemorrhage in vagal nerve, myocardium and endometrium, 6) gastric erosion, 7) cloudy swelling of kidneys, 8) enterocolitis, 9) focal necrosis of liver and adrenals, 10) demyelination of cranial nerves, and 11) focal hyaline degeneration of striated and smooth muscles and myocardium. The botulinus toxin was confirmed from the samples of cardiac blood or autopsy.

Botulinum Toxins↗

Electron microscopic observations on Aedes albopictus cells infected with dengue viruses.

In dengue virus infected Aedes albopictus cells, electron-dense particles, larger than single ribosomes, were arranged on the cytoplasmic sides of rough endoplasmic reticulum (RER) membranes. Mature virions 40--45 nm in diameter as well as vesiculotubular structures 50--120 nm in diameter appeared in enlarged cisternae of RER filled with fine granular substance. Many of the mature virions and somewhat degenerated vesiculotubular structures remained to be enclosed in membranous structures presumably derived from RER, even after degeneration of infected cells. The findings suggest that development of dengue viruses in cultured A. albopictus cells takes place in close relationship with the activated membranes of RER. Other morphological changes observed in dengue infected A. albopictus cells were 1. electron-dense "double-track structures" in areas of virion morphogenesis, 2. fine crystalline structures in type-2 dengue infected cells, and 3. aggregates of nucleoid structures, in cells persistently infected with type 2 dengue virus. The implication and nature of these structures in relation to virion morphogenesis remain to be investigated.

Aedes↗

Histopathological studies on experimental Yersinia enterocolitica infection in animals.

Experiments were made using mice, rabbits, and monkeys. Mice were divided into 2 groups: an intravenously injected group and an orally administered one. In either group, lesions were found mainly in mucous membranes on Peyer's patches of intestines. Lesions consisted of formation of bacterial colonies accompained by accumulation of neutrophils and histiocytes, and proliferation of reticulum cells. Severe intestinal lesions were common to the 3 animals. Apart from the intestines, the liver showed most remarkable changes. Next ranked changes in bone marrows and spleen. Mesenteric lymph nodes revealed no significant changes. On the other hand, nonpathogenic strains caused little change.

Animals↗

A modified PAP (peroxidase-anti-peroxidase) staining technique using sera from patients with dengue hemorrhagic fever (DHF): 4 step PAP staining technique.

BHK-21 cells infected with dengue virus type 1 were stained by a newly developed 4 step PAP (peroxidase-anti-peroxidase) technique using sera from patients with dengue hemorrhagic fever as anti-virus antibody. The intensity of staining of the sera was proportional to the hemagglutination inhibition and neutralization titers. With this new technique using sera from patients it should be possible to use the PAP technique of virus infections.

Animals↗

Hemagglutinin prepared from cells of Aedes albopictus, clone C6/36, infected with type 1 dengue virus.

A high titer of hemagglutinin (HAnin) was found in culture fluids of cells of Aedes albopictus, clone C6/36, infected with type 1 dengue virus. The HAnin (TC antigen) was associated with complete virions and no appreciable small-sized HAnin was produced, in contrast to the case in an infected suckling mouse brain (SMB) homogenate, in which most of the HAnin is smaller than complete virions. Extraction of the TC antigen with Tween 80-ether disrupted the HAnin into smaller-sized particles, resulting in complete loss of infectivity (TE-TC antigen), but it did not affect the titer or reactivity of the HAnin. Comparative hemagglutination-inhibition (HI) assay of human sera using TC antigen, TE-TC antigen or standard antigen extracted from infected SMB (SMB antigen) showed that TC or TE-TC antigen could be used for routine diagnostic or epidemiological HI tests instead of SMB antigen, which is rather hard to prepare.

Aedes↗

Neutralization tests for dengue and Japanese encephalitis viruses by the focus reduction method using peroxidase-anti-peroxidase staining.

Neutralization tests were made on 4 types of dengue (DEN) virus and Japanese encephalitis (JE) virus by incubation of serially diluted antisera and constant amounts of the viruses and then focus assay of surviving virus infectivity with peroxidase-anti-peroxidase (PAP) staining. Neutralization reactions were virtually completed in 2 hr on incubation of serum-virus mixtures at 28 C. A straight regression line was obtained on a probit chart by plotting the focus reduction rates at various dilutions of a given serum against the logarithm of the serum dilution used in the test. The slopes of the probit regression lines for the neutralization for DEN types 1 and 3 were similar, but differed somewhat from those for DEN type 2 and type 4. The slope of the line for JE virus was quite different from those for DEN viruses. Using these relations, the fifty percent focus reduction titer (FR50) of neutralizing antibodies of a given serum could be estimated from the focus reduction rates at several dilutions of the test serum when the latter was between 25-75% of the value of the control.

Animals↗

Changes in dengue and Japanese encephalitis (JE) antibody after JE vaccination.

Serological studies before and after Japanese encephalitis (JE) vaccination were made on subjects of various ethnic groups with or without dengue and/or JE antibodies. In these subjects dengue and JE hemagglutination-inhibition (HI) and neutralization (N) antibodies were measured. Seroconversion to JE was observed in about 45% of the subjects by the HI test and 63% by the N test, whereas seroconversion to dengue with only 4-fold increase in titer after vaccination was detected in 14% by the HI test and in a single case (3%) by the N test. The presence of JE and/or dengue antibody in the prevaccination sera did not significantly influence the seroconversion rates of JE-HI and N-antibodies after vaccination. Moreover the seroconversion rate did not seem to vary markedly in different ethnic groups, although tendencies for subjects from Southeast Asia to have dengue antibodies and Japanese people to have JE antibodies were demonstrated. The presence of dengue N-antibodies in the prevaccination sera did not significantly influence the geometrical mean titer of postvaccination JE-N antibody. Thus the antibody response to JE vaccination was fairly specific to JE, and no marked secondary response was observed.

Adult↗

Improved rapid method for electron microscopy of macro- and micro-tissue cultures.

A rapid method of embedding macro- and micro-tissue cultures is described. The procedure involves use of a preshaped BEEM capsule for pelleting, fixation and embedding of tissue culture cells for electron microscopy. To obtain good contrast specimens prepared by this rapid method need a rather longer staining time with uranyl acetate than specimens prepared by standard methods. THis procedure takes only about 200 min from fixation and embedding to double staining with uranyl acetate and lead citrate. It should be useful for both monolayer tissue cultures and organ cultures in diagnostic and research studies on viral agents.

Culture Techniques↗