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M Ohkuma

Publications and source records attributed to M Ohkuma.

At least 73 records · Page 4Linked to original sources
PubMed1991

Presence of melanophages in the normal Japanese skin.

Human skin samples were obtained from the normal peripheral portion of specimens removed from persons with various cutaneous and systemic diseases. A portion of each specimen was embedded in paraffin and another part in water-soluble embedding medium, and some was frozen in liquid nitrogen for light microscopy and histochemistry. Some specimens were also investigated by electron microscopy. In 31 of 32 specimens, cells containing brown pigment were observed in the superficial dermis. Because both acid phosphatase and Masson-Fontana staining were positive and the 3,4-dihydroxyphenylalanine reaction negative, the cells were considered to be melanophages. Electron microscopic examination revealed that these cells contained melanosome-laden phagosomes. Some fibroblastlike cells were also observed with intracellular single or multiple melanosomes. This study documents the occurrence of melanophages in the normal skin of Japanese subjects.

Acid Phosphatase↗
PubMed1991

Evidence that more than one gene encodes n-alkane-inducible cytochrome P-450s in Candida maltosa, found by two-step gene disruption.

An n-alkane-assimilating yeast, Candida maltosa, has a diploid genome. Probed with the previously isolated gene of n-alkane-inducible cytochrome P-450 (P-450alk), its allelic gene had been isolated, its nucleotides sequenced, and the interallelic divergence examined. Using one of the allelic genes, we disrupted the two alleles of the cytochrome P-450alk gene by a two-step gene disruption system. Surprisingly, the disruptant still assimilated n-alkane and contained n-alkane-inducible cytochrome P-450. This result indicates that, other than the disrupted two alleles, there is at least one other gene that encodes an n-alkane-inducible cytochrome P-450.

Alkanes↗
PubMed1990

[MRI of lymphedema using short-TI-IR (STIR)].

Thirty four cases with lymphedema of the extremities were examined with MRI at 0.5 tesla. On T1-weighted image, the enlarged subcutaneous tissue and the subcutaneous trabecular structures were seen in all cases. Moreover, the trabecular structures in the enlarged subcutaneous tissue showed low signal intensity on T1-weighted image and high signal intensity on T2-weighted image in all cases. Additionally, in 12 of 15 cases examined by Short-TI-IR (STIR) image, the trabecular structures and fluid collections in the subcutaneous tissue were shown more definitely in high signal intensity than by T2-weighted image. We consider MRI using STIR is to be useful in the evaluation of edematous disease.

Female↗
PubMed1989

An improved host-vector system for Candida maltosa using a gene isolated from its genome that complements the his5 mutation of Saccharomyces cerevisiae.

The host-vector system of an n-alkane-assimilating-yeast, Candida maltosa, which we previously constructed using an autonomously replicating sequence (ARS) region isolated from the genome of this yeast, utilizes C. maltosa J288 (leu2-) as a host. As this host had a serious growth defect on n-alkane, we developed an improved host-vector system using C. maltosa CH1 (his-) as host. The vectors were constructed with the Candida ARS region and a DNA fragment isolated from the genome of C. maltosa. Since this DNA fragment could complement histidine auxotrophy of both C. maltosa CH1 and S. cerevisiae (his5-), we termed the gene contained in this DNA fragment C-HIS5. The vectors were characterized in terms of transformation frequency and stability, and the nucleotide sequence of C-HIS5 was determined. The deduced amino acid sequence (389 residues) shared 51% homology with that of HIS5 of S. cerevisiae (384 residues; Nishiwaki et al. 1987).

Base Sequence↗
PubMed1989

Lipoperoxide in dog thoracic duct lymph.

Lipoperoxide levels were examined in thoracic duct lymph (TDL) of 11 dogs. In four dogs with sodium citrate added in vitro to prevent coagulation, TDL had notably higher levels than in serum. After centrifugation, however, lymph supernatant levels of lipoperoxide closely approximated that in serum suggesting that the bulk of lipoperoxide remained in the sediment and derived from circulating cells. Interstitial accumulation of lipoperoxide, a breakdown product of cell membranes, may be a potent "toxic factor" responsible for trophic changes associated with chronic lymph-edema.

Animals↗
PubMed1988

Epidermal plasminogen activator inhibitor (PAI) is immunologically identical to placental-type PAI-2.

Plasminogen activator inhibitor (PAI) purified from human epidermis [(1986) FEBS Lett. 408, 273-277] was immunologically identified as placental-type PAI-2. In both fibrinolytic and synthetic substrate assays inhibitory activity of epidermal PAI was neutralized by anti-PAI-2, but not by anti-endothelial type PAI-1. Immunoblotting technique confirmed that the purified epidermal PAI is reactive with anti-PAI-2, but not with anti-PAI-1. Consequently PAI in human epidermis was demonstrable by immunohistochemical technique.

Antibodies, Monoclonal↗
PubMed1988

The developmental changes of ERGs on spontaneous retinal degeneration of Celestial goldfish.

The Celestial goldfish, which belongs to the family of telescope-eye goldfish, displays unique spontaneous retinal degeneration associated with developmental anterodorsal protrusion of the eyeball. We observed concurrent changes in the electroretinogram. At the age of 75 days, the retinal layer was developed fully and the electroretinogram exhibited b-wave dominance similar to that of adult common goldfish. At the age of 105 days, when the eyeball began to protrude laterally, the b-wave amplitude decreased to 52% of its earlier developmental stage, with a prolonged peak time. Histologic change was observed in the retinal pigment epithelium and photoreceptor layers. At the age of 135 days, when the eyeball protruded further anterodorsally, the histologic changes extended to all retinal layers and the ERG b-wave was extinguished. Electrophysiologic and histologic changes in the Celestial goldfish eye were found to be proportional to the grade of eye protrusion. Since similar goldfish do not show these changes, however, the Celestial goldfish may be a new model of hereditary retinal degeneration.

Animals↗
PubMed1987

Electrophysiological studies of spontaneous retinal degeneration in celestial goldfish (chotengan).

Spontaneous retinal degeneration of Celestial goldfish was studied histologically and electrophysiologically. Retinal degeneration was divided into three stages. Until the age of 75 days (Stage 0) the retina showed normal histological development and the electroretinograms (ERGs) exhibited dominant b-waves similar to those of adult common goldfish. By the age of 105 days (Stage 1), when the eyeballs began to protrude laterally, histological changes were first observed in the retinal pigment epithelium and photoreceptor layer. The b-wave amplitude decreased to 52% of that of Stage 0 with a prolongation of the peak latency. By the age of 135 days (Stage 2), when eyeballs protruded further anterodorsally, the retinal degeneration extended to the entire retinal layers and no b-waves were detected. The deterioration of the b-wave amplitude was closely correlated to the histological findings of retinal degeneration. The Celestial goldfish is considered to be a new model of hereditary retinal degeneration.

Animals↗
PubMed1986

Experimental chloroquine retinopathy.

Chloroquine retinopathy was produced experimentally in the eye of the albino corydoras (one of the tropical fish) by daily administration of chloroquine (0.1 mg per os). The enucleated eyes were examined from the 14th day to 3 months after the beginning of drug administration under light and electron microscopy. The first change of retina was the appearance of membraneous cytoplasmic body (MCB) in the cytoplasm of ganglion, amacrine, bipolar and horizontal cells. MCB might be degenerated lysosome. They showed lamellar figures or crystalline lattice-like structures. Secondarily, these MCB appeared in the inner segments of photoreceptor cells. The outer segments of rod cells disappeared, and then those of cone cells. Although photoreceptor cells were diminished in number in advanced degeneration, the cells of inner nuclear layer and ganglion cells were maintained in number. The presence of MCB dose not mean death of cells. The retinal pigment epithelial cells contained MCB in its cytoplasm only in severe degenerative cases, and did not show other remarkable changes. MCB also appeared in the cytoplasm of pericytes of retinal vessels. Chloroquine is considered to damage directly photoreceptor cells most severely.

Animals↗
PubMed1982

Retinal degeneration in celestial goldfish. Developmental study.

The celestial goldfish were systematically reared from fertilization for life, revealing developmental processes of retinal degeneration. The eyes began to protrude laterally at the age of 90 days, rotated antero-dorsally at 120 days, and thus the 'celestial eye' was completed. The retina developed to normal mature structure by the age of 50 days. No degenerative findings were revealed before the start of eye extrusion. The first morphological change, irregular distribution of melanin granules in the pigment epithelial layer and disorientation of the outer segments of photoreceptors, was detected at the age of 90 days. At 120 days, the pigment epithelial layer lost melanin granules at places and was occupied by phagocytes. Photoreceptor cells were destroyed, and phagocytes, containing melanin granules, appeared in the inner retina and/or choroid. The retinal degeneration started simultaneously with eye protrusion. The regular telescopic-eye goldfish have large, extended eyes as those of celestial goldfish, but they develop no retinal degeneration. Celestial goldfish seems to be an interesting new type of hereditary retinal degeneration in vertebrates.

Animals↗
PubMed1981

Freeze-fractured replica of Schlemm's canal and the trabecular meshwork in the primate.

Using a freeze-fracture technique, the fine structure of the Schlemm's canal and trabecular meshwork in the monkey was studied with special reference to intercellular junctions. Gap junctions were observed between the endothelial cells of Schlemm's canal and between the trabecular meshwork cells. Maculae occludentes were rarely observed between the endothelial cells of the inner wall of Schlemm's canal. The trabecular meshwork cells appeared to act in an electrotonic and metabolic syncytium.

Animals↗