Search PubMed⌕ Search

Biomedical subjects

M Osumi

Publications and source records attributed to M Osumi.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Serodiagnosis of tuberculosis by detection of antituberculous glycolipid antigen (TBGL antigen) antibodies in serum using enzyme-linked immunosorbent assay: clinical evaluation of anti-TBGL antibodies assay kit].

Kyowa Medex Co., Ltd. developed the kit for the sero-diagnosis of tuberculosis, which detects IgG antibodies against tuberculous glycolipids antigen containing cord factor (TBGL antigen) prepared from M. tuberculosis using the enzyme-linked immunosorbent assay technique. We evaluated the kit using clinical specimens and the results are as follows: 1) In total, 34 out of 39 cases (87.2%) with active pulmonary tuberculosis showed positive anti-TBGL antibody. 2) Patients with cavity, patients with extensive lesions and patients excreting large amount of acid fast bacilli tended to show high positivity rates. 3) The antibody titers increased in 7 out of 11 cases after starting the antituberculous chemotherapy. 4) The use of the antibody is unsuitable for the determination of the activity of tuberculosis since the antibody titers only slightly decreased even after chemotherapy for two years. 5) Two out of four nontuberculous mycobacteriosis cases showed high antibody titers 6) All three AIDS patients with tuberculosis showed low antibody titers. 7) The antibody was negative in almost all healthy controls showing a positive PPD skin test after vaccination with BCG, and it was therefore assumed that the antibody titer is not increased by BCG vaccination. 8) The antibody titers of the staff members working in the tuberculosis wards were not high compared with those of staff members working in the other wards.

AIDS-Related Opportunistic Infections↗
PubMed1995

Ultrastructural effects of pressure stress to the nucleus in Saccharomyces cerevisiae: a study by immunoelectron microscopy using frozen thin sections.

The effects of hydrostatic pressure on subcellular structures, particularly the nucleus, of Saccharomyces cerevisiae were investigated by immunoelectron microscopy. Cells were treated with hydrostatic pressure from 0.1 to 400 MPa for 10 min at room temperature. Frozen thin sections of the cells revealed that spindle pole bodies disappeared at 100 MPa. At 150 MPa, the deposition of gold particles for anti alpha-tubulin was noticed in the nucleus, although the filamentous structure of microtubules was lost. At 200 MPa, fewer gold particles were scattered in the nucleus and the nuclear membrane in several portions was also observed to be open at 300 MPa. These results show that elements of the nuclear division apparatus were susceptible to pressure stress, particularly spindle pole bodies and microtubules. The damage to spindle pole bodies, microtubules, and nuclear membrane caused by pressure stress was followed by the inhibition of nuclear division. After the release of pressure, the spindle pole bodies and microtubules of pressurized cells at below 200 MPa regained their normal appearance at 24 h.

Cell Division↗
PubMed1995

Changes in cytokeratin expression in epidermal keratinocytes during wound healing.

In order to investigate the re-epithelialization process during wound healing, the hair on the back of guinea pigs was shaved and then excisional wounds were made through the entire thickness of the skin. Histological changes were observed and changes in the expression of different cytokeratin polypeptides were examined using an immunohistochemical technique. Immunohistochemical study revealed that the proliferating and migrating keratinocytes expressed the same cytokeratins as the basal cells of normal epidermis. In addition, the entire epidermis of fairly remote areas from the edges of the wound where no thickening was observed showed a temporarily abnormal staining pattern. The suprabasal cells in the regenerating epidermis temporarily expressed cytokeratins not only specific for suprabasal cells but also specific for basal cells. The cytokeratins expressed in normal basal keratinocytes were also present in the thickened granular layers. These data indicate that the expression of cytokeratins in the epidermal keratinocytes (even in fairly remote areas from the wound edges) changes during wound healing, that the origin of the migrating keratinocytes from the remaining epidermis seems to be the basal cells in the epidermis, and that the appearance of keratohyalin granules is not related to changes in cytokeratin expression.

Animals↗
PubMed1995

Detection of Mycobacterium tuberculosis in clinical specimens other than sputum by a specific DNA probe with amplification of the ribosomal RNA.

OBJECTIVE: To evaluate the Gen-Probe Amplified Mycobacterium tuberculosis Direst Test (MTD) for detection of Mycobacterium tuberculosis in clinical specimens other than sputum, especially cerebrospinal fluid (CSF) and pleural fluid (PF) specimens. DESIGN: Six CSF, 17 PF and 23 bronchoalveolar lavage fluid (BALF) specimens that were submitted to our clinical laboratory for detection of mycobacteria were subjected to MTD and conventional smear and culture examinations. RESULTS: Of 6 smear-negative CSF specimens, two were positive in MTD and culture examination. In PF specimens, two of 15 smear- and culture-negative specimens were positive in MTD, while one smear-negative but culture-positive specimen was MTD negative. Three of 20 smear- and culture-negative BALF specimens were positive in MTD. Three BALF specimens in which mycobacteria other than the M. tuberculosis complex detected by culture were negative in MTD. CONCLUSION: MTD is very useful for rapid detection of M. tuberculosis in clinical specimens other than sputum as well as sputum, and should be especially valuable for rapid diagnosis of tuberculous meningitis which requires prompt initiation of appropriate anti-tuberculosis drug treatment.

Bronchoalveolar Lavage Fluid↗
PubMed1995

[Longitudinal observation of pulmonary tuberculosis patients by Gen-Probe Mycobacterium tuberculosis direct test (MTD)].

To study the clinical significance of conducting Gen-Probe Mycobacterium tuberculosis Direct Test (MTD) during the course of the disease, sputum specimens from 19 pulmonary tuberculosis patients were smeared, cultured, and tested by MTD, once a month for five months from the initiation of chemotherapy. 1) MTD-positive rates declined in parallel with decreased pulmonary tuberculosis activity, and the MTD findings of 16 patients who presented mild to moderate pulmonary tuberculosis at admission became negative by four months after the beginning of treatment. Three patients (15.8%) who were consistently positive for MTD during five months after the beginning of treatment were serious pulmonary tuberculosis patients, excreting a large number of organisms at admission. 2) During the course, a total of 43 MTD negative findings were observed, of which one (2.3%) was positive for Ogawa medium culture and the other 42 (92.7%) were negative. MTD was useful in briefly determining the absence of infection, provided that a negative culture on Ogawa medium means no infection. 3) Eleven of the 12 specimens (91.7%) showing positive smears and negative cultures on Ogawa medium were positive for MTD. Since MTD shows negative results for atypical mycobacteria, this is a very useful test in identifying acid fast bacilli which shows a positive smear and a negative culture.

Humans↗
PubMed1995

[Two cases of tuberculous meningitis diagnosed rapidly by amplified mycobacterium tuberculosis direct test (MTD)].

The Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test (MTD) is a rapid direct specimen assay method for identification of M. tuberculosis by amplification of ribosomal RNA and detection of the product with a specific chemiluminescent DNA probe. We report two cases of tuberculous meningitis which were positive in the MTD. Since the cerebrospinal fluid showed negative smears and positive cultures in both cases, we could diagnose tuberculous meningitis by MTD about 2 months earlier than by conventional smear and culture methods. In one patient, the fever didn't subside immediately after staring chemotherapy. In the other patient, an intracerebral focus appeared after administration of antituberculosis drugs. However, we did not hesitate to continue the therapy because of the MTD positive findings. MTD is considered to be a very useful test especially in diseases like tuberculous meningitis which need rapid diagnosis and rapid therapy, and is useful for improvement of convalescence and is economical.

Aged↗
PubMed1995

Analysis of the membrane structures involved in autophagy in yeast by freeze-replica method.

Under starvation conditions, the yeast S. cerevisiae sequesters its own cytoplasmic components by forming autophagosomes with double membrane in the cytoplasm. The autophagosome then fuses with the vacuolar membrane and delivers its own cytoplasmic components into the vacuole in the form of an autophagic body with a single membrane (Baba, M., Takeshige, K., Baba, N., and Ohsumi, Y. 1994. J. Cell Biol., 124: 903-913). We examined membrane structures involved in the autophagy induced by nitrogen-starvation by using freeze-replica method. The most conspicuous characteristic of the autophagic body is that the intramembrane particles were rarely detected on either the protoplasmic or exoplasmic face of its fracture membrane. This morphological feature of the fractured face was clearly different from other intracellular organelles. Next we examined the autophagosomal membrane. The inner membrane of autophagosome was also intramembrane particle-free, and its morphological feature was identical to the membrane of autophagic body. At the fusion site between autophagosome and vacuole we obtained direct evidence that two different membranes, the outer membrane of autophagosome and vacuolar membrane, became continuous by using freeze-etching technique. From these results we concluded that the autophagic body originated from the inner membrane of the autophagosome, and its membrane reflects an intrinsic feature of autophagosomal membrane. The outer membrane of autophagosome had only a few intramembrane particles and may be differentiated from the inner membrane. In cells under nitrogen-starvation condition, the density of intramembrane particles of vacuolar membrane decreased beyond that in control cells.

Autophagy↗
PubMed1995

Ultrahigh-resolution low-voltage SEM reveals ultrastructure of the glucan network formation from fission yeast protoplast.

The refined field emission SEM, S-900 LV which gives better resolution especially at low voltages below 5 kV was developed for ultrahigh resolution scanning electron microscopy. A visualization test at x 300,000 was made using a gold-evaporated magnetic tape, and the resolution was found to be about 1 nm at 2.5 kV. The ultrastructure of the cell wall, especially the reverting glucan network, from the protoplast of Schizosaccharomyces pombe was studied using this improved ultrahigh-resolution low-voltage SEM (UHR-LVSEM). The results with uncoated reverting protoplasts observed with this microscope revealed that the network was originally formed as secreted particles scattered on the protoplast surface and these were subsequently stretched to microfibrils about 2 nm thick. The microfibrils were twisted around each other and joined together so that they developed into 8-nm-thick fibrils, forming a ribbon-shaped network of glucans about 16-nm-thick which covered the entire protoplast surface. The UHR-LVSEM images of reverting protoplasts treated with glucanase confirmed that the particles scattered on the protoplast surface in the initial stage of regeneration were glucan in nature.

Animals↗
PubMed1994

Fission yeast protein kinase C gene homologues are required for protoplast regeneration: a functional link between cell wall formation and cell shape control.

Two novel protein kinase C (n PKC) gene homologues, pck1+ and pck2+ were isolated from the fission yeast Schizosaccharomyces pombe (Toda et al. (1993) EMBO J. 12, 1987). We examined the functional differences of pck1+ and pck2+ in cell wall formation and actin organization of S. pombe. Regenerating protoplasts of a wild-type strain, single gene disruptants of pck1+ (delta pck1) and pck2+ (delta pck2) were used as a simple model to examine the functional links between PKC, cell wall formation and actin organization. Protoplasts of the wild-type strain and those of delta pck1 reverted to intact cells in osmotically stabilized liquid medium. A close spatial association between new cell wall formation and actin was observed in these two strains. In delta pck2, protoplasts did not revert to intact cells: (1) scarcely any new cell wall material was formed; (2) actin was not reorganized; and (3) nuclear division and an increase in the amount of cytoplasm were observed in the regenerating protoplasts. These findings demonstrate that the pck2+ gene has a function essential for protoplast regeneration but the pck1+ gene does not. Involvement of n PKCs in cell wall formation and actin organization was also clarified. The effect of staurosporine (a potent inhibitor of protein kinases) on regenerating protoplasts of the three strains confirmed the assumption that the pck2 protein is an in vivo target of staurosporine in the fission yeast.

Actins↗
PubMed1994

[Efficacy of the "Gen-Probe Mycobacterium Tuberculosis Direct Test (MTD)" for detection of Mycobacterium tuberculosis in clinical specimens--comparison between the MTD and the test by culture on Ogawa's egg medium or in the MB Check System].

Three or more weeks are usually required for detecting Mycobacterium tuberculosis by the known culture methods, and therefore, the development of a rapid bacteriological diagnostic method for M. tuberculosis has been urgently awaited. Recently, Gen-Probe Inc. has developed the "Gen-Probe Mycobacterium Tuberculosis Direct Test (MTD)", which is based on amplification of the ribosomal RNA (rRNA) of M. tuberculosis in clinical specimens and hybridization of the amplified rRNA with a M. tuberculosis-specific DNA probe, as a rapid direct diagnostic method for tuberculosis. We therefore compared the sensitivity and specificity of the MTD in detecting M. tuberculosis with the culture methods on Ogawa's egg medium and in the MB Check System, using 107 clinical specimens as test material. The results obtained are as follows: 1. Of the 61 clinical specimens which were negative when cultured on Ogawa's egg medium, 13 (21.3%) were positive for M. tuberculosis using the MTD, and of the 48 clinical specimens which were negative when cultured in the MB Check System, 8 specimens (16.7%) were positive for M. tuberculosis using the MTD. 2. All of the specimens which yielded growth of M. tuberculosis (identified by the DNA probe) either on Ogawa's egg medium or in the MB Check System, except one, were positive for M. tuberculosis in the MTD. The only one exception was a specimen which was positive for M. tuberculosis in both Ogawa's medium and the MB Check System.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Morphological changes of Candida albicans induced by BMY-28864, a highly water-soluble pradimicin derivative.

The time course of BMY-28864-dependent morphological changes in Candida albicans A9540 was studied by electron microscopy. Scanning electron microscopy revealed that BMY-28864 often induced cell surface deformations such as abnormal swelling and bulging around budding sites and bud scars. The cell membrane damage was visualized by freeze-fracturing technique as deep pit-like invaginations. Transmission electron microscopy with thin-sectioned specimens also demonstrated that BMY-28864 induced cell membrane invaginations together with cell membrane detachment from the cell wall, nuclear membrane fragmentation and mitochondrial aberration. Statistical sequence analysis of the prominent BMY-28864-dependent morphological changes of the yeast cells led to the conclusion that BMY-28864 first attacked the cell membrane and then caused disintegration of other intracytoplasmic organelles, resulting in the lethal effect.

Anthracyclines↗
PubMed1992

Beta-oxidation of butyrate, the short-chain-length fatty acid, occurs in peroxisomes in the yeast Candida tropicalis.

When an n-alkane-utilizable yeast, Candida tropicalis pK233, was cultivated on butyrate, the fatty acid of shortest chain-length for beta-oxidation, as the sole source of carbon and energy, catalase and the enzymes of the fatty acid beta-oxidation system were inducibly synthesized at high levels. As in the alkane-grown cells, the proliferation of peroxisomes was harmonized with the induction of peroxisomal enzymes. The results of subcellular fractionation and immunoelectronmicroscopy indicated the localization of these enzymes in peroxisomes, not in mitochondria. It was suggested that only peroxisomes have a role in fatty acid beta-oxidation in the yeast cells, unlike in mammalian cells, in which cooperation between peroxisomes and mitochondria is essential.

Acetyl-CoA C-Acyltransferase↗
PubMed1992

Physiological roles of acetoacetyl-CoA thiolase in n-alkane-utilizable yeast, Candida tropicalis: possible contribution to alkane degradation and sterol biosynthesis.

The presence of two types of thiolases, acetoacetyl-CoA thiolase and 3-ketoacyl-CoA thiolase, was demonstrated in peroxisomes of n-alkane-grown Candida tropicalis [Kurihara, T., Ueda, M., & Tanaka, A. (1989) J. Biochem. 106, 474-478], while acetoacetyl-CoA thiolase was also shown to be present in cytosol. The activity of the enzyme in cytosol was constant irrespective of culture conditions, while the peroxisomal enzyme was inducibly synthesized in the alkane-grown yeast cells. These results indicate that peroxisomal acetoacetyl-CoA thiolase participates in alkane degradation, while the cytosolic enzyme is associated with other fundamental metabolic processes, probably sterol biosynthesis, because this enzyme can catalyze the first step of the sterol biosynthesis. 3-Hydroxy-3-methylglutaryl (HMG)-CoA reductase, a key regulatory enzyme of sterol biosynthesis, was found to be localized exclusively in microsomes of the alkane-grown yeast cells. These results suggest that yeast peroxisomes do not contribute to sterol biosynthesis, unlike the case of mammalian cells.

Acetyl-CoA C-Acetyltransferase↗
PubMed1992

Morphological changes associated with growth inhibition of Trichophyton mentagrophytes by amorolfine.

Amorolfine inhibited the in-vitro growth of Trichophyton mentagrophytes to some extent at a low drug concentration of 0.8 ng/ml. Corresponding to the growth inhibition, SEM studies revealed a slight modification of hyphal morphology, i.e. a waving of the hyphal surface. These morphological alterations were more extensive with increases in drug concentration and treatment period: collapsed and distorted hyphae and exfoliation of the surface of T. mentagrophytes occurred at 8 ng/ml and marked deformation and disruption of the hyphal structure at 80 ng/ml of amorolfine. TEM revealed thickening of the cell walls and the accumulation of electron-dense granular structures in both the wall and cytoplasm in thin-sectioned cells pretreated with 8 ng/ml or more of amorolfine, although the nuclear and mitochondrial architecture was not noticeably influenced. Cytoplasmic membranes and other membranous structures of organelles such as nuclei and mitochondria were disrupted or fused, thereby losing their essential physiological activity in hyphal cells pretreated with 80 ng/ml of amorolfine. The ultrastructural study thus supports the observation that morphological changes of T. mentagrophytes caused by amorolfine were associated with its growth-inhibitory and killing activity, which depended on the drug concentration and treatment time.

Antifungal Agents↗
PubMed1992

Immunoelectron microscopic localization of thiolases, beta-oxidation enzymes of an n-alkane-utilizable yeast, Candida tropicalis.

The location of acetoacetyl-CoA thiolase (T-I) and 3-ketoacyl-CoA thiolase (T-III), enzymes of the fatty acid beta-oxidation system, was studied in n-alkane-grown Candida tropicalis cells by immunoelectron microscopy using a post-embedding method with colloidal gold conjugated IgG. The deposition of gold particles for T-I was detected in the microbodies and cytoplasm and that of gold particles for T-III specifically in the microbodies. The double labeling technique confirmed that T-I and T-III occurred concurrently in a microbody and T-I also in cytoplasm. These results were consistent with the biochemical data based on subcellular fractionation and indicated that the yeast beta-oxidation system operates efficiently only in the microbodies.

Acetyl-CoA C-Acetyltransferase↗
PubMed1991

Electron microscopic observation of recombinant Escherichia coli cells overproducing human tumor necrosis factor-alpha mutant as inclusion bodies.

Escherichia coli C600 r-m- carrying plasmid pTNF483 (E. coli [pTNF483]) produces a tumor necrosis factor-alpha (TNF-alpha) mutant protein in an insoluble form. A swollen region was observed in the SEM images to encircle the outside of most of the E. coli [pTNF483] cells just like a bandage. On the other hand, inclusion bodies of the TNF-alpha mutant as large as the short axis of the cell were observed in TEM images. This position was regarded as coinciding with the swollen region of SEM images. The inclusion bodies revealed in the swollen region of the cell envelopes were clearly observed in SEM images of isolated insoluble structures obtained by centrifugal sedimentation of a sonicated cell suspension.

Escherichia coli↗