Biomedical subjects

K Takeo

Publications and source records attributed to K Takeo.

153 records · Page 9Linked to original sources

PubMedDate not supplied

Pathogenicity of strains of the black yeast Exophiala (Wangiella) dermatitidis: an evaluation based on polymerase chain reaction.

Strains of Exophiala dermatitidis, mainly originating from patients with systemic neurotropic mycosis in Asia and from the lungs of patients with cystic fibrosis (CF) in Europe, were analysed by ribotyping of the small subunit rDNA and by random amplification of polymorphic DNA (RAPD). A characteristic banding pattern for the species was found after restriction analysis of amplified fragments V9 and ITS4. The small subunit rDNA gene of five strains was about 1800 base pairs (bp) long, while in 16 strains its length was about 3000 bp. Using RAPD, seven populations could be distinguished. European CF strains as well as Asian strains from systemic mycoses are mainly distributed over two populations, one of which contained both CF strains and a systemic strain. It is concluded that the two clinical pictures are caused by genetically similar strains. The differences in pathogenicity may be explained by immunological differences in the hosts or by differences in exposure to the fungal propagules.

Base Sequence↗

PubMedDate not supplied

Cell-surface hydrophobicity and lipolysis as essential factors in human tinea nigra.

Hydrophobic adhesion of cells of the black yeast Hortaea werneckii (Horta) Nishimura & Miyaji, causative agent of human tinea nigra, was established by microbial adhesion to hexadecane (MATH) and adhesion to polystyrene, and compared with adhesion of other species of black yeasts. Additional ecophysiological tests were performed. Hortaea werneckii cells proved to have a high degree of hydrophobicity (98.5% MATH). The species is unable to degrade keratin, but shows significant lipolytic activity. It is concluded that H. werneckii is a commensal, that shows lipophilic adhesion to human skin and survives by the assimilation of excretion products.

Animals↗

PubMedDate not supplied

Chlamydospore formation by Paracoccidioides brasiliensis mycelial form.

To investigate the role of some adverse environmental conditions in chlamydospore formation by the mycelial form of P. brasiliensis, we cultured four P. brasiliensis isolates (18, Bt4, 1183, Pb9) at 25 degrees C within solid agar medium either rich or poor in nutrients. Isolates 18 and 1183 were also cultured under anaerobiosis in a nitrogen atmosphere. Isolate 18 produced great number of terminal and intercalary chlamydospore after 7-10 days of culture in a medium poor in nutrients (2% agar with 0.1% dextrose and polypepton). The three other isolates also produced chlamydospores under the same conditions, but in lower numbers. Chlamydospore production by isolate 18 was abolished when the fungus was cultured in two agar media rich in nutrients (brain heart infusion and potato dextrose agar). Anaerobic incubation of isolate 18 under an atmosphere of N2 showed small mycelial outgrowth with numerous chlamydospores. At the electron microscopical level, the chlamydospores showed one or various nuclei and numerous mitochondria, indicating great potential for further development. Accordingly, chlamydospores produced multiple budding after only 24 h incubation at 35 degrees C. The results demonstrate that under adverse environmental conditions P. brasiliensis mycelial form produces chlamydospores within a short period of time.

Culture Media↗

PubMedDate not supplied

Experimental paracoccidioidomycosis in hamster: transmission electron microscopy of inoculation site lesion.

Interaction between Paracoccidioides brasiliensis (Pb) and inflammatory cells in hamster testis was studied sequentially by transmission electron microscopy. In early lesions (six hours after inoculation), polymorphonuclear neutrophils (PMNs) were the major and mononuclear cells and eosinophils were the minor constituents of the inflammatory cells. PMNs were later replaced by mononuclear cells. Viable Pb cells were phagocytosed or surrounded by inflammatory cells. Preserved Pb cells usually had broad host-parasite interphases, whereas dying ones had narrow interphases. The outer layer of the fungus wall was sometimes broken by PMN in some focal points, broken pieces being peeled off and phagocytosed. Small Pb cells were uninuclear, and were often related to broad interphase. Large Pb cells were multinucleated with irregularly shaped wall, and sometimes had lomasome and/or myelin like structures. Different interaction patterns of Pb with inflammatory cells may be due to functionally different host cell flow to the inoculation site or due to the age of Pb cells or both.

Animals↗

PubMedDate not supplied

Health workers' attitudes toward euthanasia in Japan.

Despite impressive life-saving medical advancements, diseases for which there are no cure still exist. In the past doctors and health workers in Japan often preferred not to disclose the diagnosis of an incurable disease--particularly cancer--to patients. A 1980 study revealed that only 17% of the Japanese doctors questioned actually had the experience of informing their patients they had cancer, while reportedly in the US 98% of doctors inform patients they have cancer. This attitude in Japan, however, is changing. And with this change such issues as care of the terminally ill after being informed about their diagnosis, human rights problems and other issues have arisen. In fact, euthanasia, although highly criticized when first introduced, is now being increasingly preferred to medical treatment that prolongs life in the presence of severe pain associated with an incurable disease. After reading a 1982 survey that revealed that 84% of the Japanese people interviewed would prefer to die with dignity rather than prolong life with a machine, four researchers decided to examine terminal care more fully, this time from the viewpoint of the medical staff. Below, their study results.

Attitude of Health Personnel↗

PubMedDate not supplied

Freeze-etching study of human and murine leprosy bacilli.

Morphologic features of the electron transparent zone (ETZ) material around human and murine leprosy bacilli were examined by a freeze-etching technic. The ETZ around human leprosy bacilli is composed of spherical droplets of hydrophobic material. These are always liquid at body temperature and they never show crystalline lamellar structure even at the temperature of liquid nitrogen. The ETZ around murine leprosy bacilli is composed of ribbon-like or membranous crystalline structures. This material is solid and crystalline at the body temperature of mice, and this solid material is the chief cause of the random arrangement of murine leprosy bacilli inside the cytoplasm of murine lepra cells. This crystalline structure has also been observed around murine leprosy bacilli grown on cell-free culture media.

Cell-Free System↗

PubMedDate not supplied

A human isolate of Exophiala (Wangiella) dermatitidis forming a catenate synanamorph that links the genera Exophiala and Cladophialophora.

A strain of the black yeast Exophiala dermatitidis displayed a hydrophobic synanamorph consisting of acropetal chains of lemon-shaped conidia, morphologically similar to those of Cladophialophora bantiana. The occurrence of the two conidial types in a single strain suggests a taxonomic affinity between Exophiala and Cladophialophora and provides support to the supposition that Cladophialophora, a possible anamorph genus of Herpotrichiellaceae, is related to black yeasts rather than to Cladosporium, which has teleomorphs in the Mycosphaerellaceae.

Exophiala↗

PubMedDate not supplied

Determination of ploidy in Cryptococcus neoformans by flow cytometry.

We determined the ploidy of Cryptococcus neoformans (28 strains) isolated from patients and nature. The cellular DNA content of these strains, which stained with propidium iodide in comparison to that of two authentic haploid strains, was determined by flow cytometry. All the strains exhibited diphasic histograms. In case of the authentic haploid strains, the first peak was centred around channel 9, and the second peak around channel 18. Most strains exhibited this type of histogram. Some strains exhibited another type of histogram: the first peak was centred around channel 18, and the second one around channel 35. In flow cytometry, the channel number is correlated with the intensity of fluorescence, namely, in proportion to the channel number the DNA content in the cells increases. The cellular DNA content of the second type of histograms showed twice that of the authentic haploid strains, and thus, five of 28 isolates were concluded to be diploid, and the others haploid.

Cryptococcosis↗

PubMedDate not supplied

Histopathological and electron microscopical studies on experimental Penicillium marneffei infection in mice.

Experimental Penicillium marneffei infection in mice was investigated histopathologically and by electron microscopy. Viable conidia (5 x 10(6) cells) of P. marneffei were inoculated into each mouse of group A (BALB/c mice) and group B (BALB/c-nu/nu-SIc mice) through the tail vein. All the mice were sacrificed at intervals and the livers were examined. In group A, the conidia were phagocytosed by Kupffer cells soon after inoculation, and proliferated by fission in the cytoplasm. Marked proliferation of yeast cells was observed 7 and 14 days after inoculation. With proliferation of the fungus, the number of lysosomes in Kupffer cells increased, and numerous granulomas were formed in the liver. These granulomas consisted mainly of macrophages with yeast cells, together with a few polymorphonuclear leukocytes, lymphocytes and giant cells. From 28 days on yeast cells were gradually cleared from the granulomas, and 56 days after inoculation almost all the granulomas disappeared. In group B, at an early stage of infection, similar pathological changes to those seen in mice of group A were observed. However, as the infection progressed, the number of granulomas continued to increase and yeast cells continued to proliferate although lymphocytes did not infiltrate these granulomas. With proliferation of yeast cells the liver tissue was replaced with both yeast cells engulfed by macrophages and extracellular yeasts, and dissemination occurred.

Animals↗