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Biomedical subjects

M Obata

Publications and source records attributed to M Obata.

At least 55 records · Page 3Linked to original sources
PubMed1989

Electrical determination of water content and concentration profile in a simulation model of in vivo stratum corneum.

Because of its efficient water-holding capacity, healthy stratum corneum (SC) can stay soft and flexible under any environmental conditions. There may be, however, a great difference in water content within the SC between the lowermost layer that faces the wet underlying living tissue and the superficial portion of the SC that is exposed to the relatively dry ambient atmosphere. To better understand the water profile of the SC and also to verify the accuracy of measurements of high frequency conductance used to evaluate the hydration state of the skin surface, we devised a simple and convenient in vitro model of the SC that stimulates the in vivo setting of the SC. It consists of an isolated sheet of SC whose lower surface covers a pad of water-saturated filter paper, and its upper surface is exposed to the ambient atmosphere. By placing this model in environments with different relative humidities (RH), we confirmed that the recorded conductance values correlated well with the actual water content of the SC (r = 0.94). Using a model having five layers of SC sheets, the water content of the innermost portion of the SC was estimated to be equivalent to about 90% of its dry weight; this level of water content remaining relatively constant over a wide range of ambient RH except in extraordinarily humid environments above 90% RH when water began to accumulate excessively in the whole SC. Using this five SC-sheet model, it was clearly demonstrated that there was an almost straight water concentration gradient from the lowermost layer to the uppermost layer of the SC. We also confirmed that the skin conductance of the high frequency current correlated well with the water content of the superficial portion of the SC as well as with that of the whole SC, therefore, it is a good parameter of the hydration state of the superficial layer of the SC.

Body Water↗
PubMed1989

Stratum corneum hydration and amino acid content in xerotic skin.

The relationship between clinical severity, the hydration state of the skin surface as assessed by a conductance with a 3.5 MHz high frequency impedance meter, and the amino acid content of the stratum corneum (SC) of six patients with ichthyosis vulgaris and 30 elderly persons with varying degrees of xerosis was investigated. With an increase in the severity of xerosis the SC showed a decrease in hydration and in its extractable amino acid content. There was a significant correlation between the hydration state and amino acid content of the SC. Although there was a significant correlation between the amino acid content of the lower leg SC and that of the forearm SC in the same subject, the former was generally lower, corresponding to the greater incidence of xerosis on the lower leg. These results suggest that a decreased amount of amino acids may be the result of low profilaggrin biosynthesis in the epidermis and that this is involved in the pathogenesis of these xerotic skin conditions. Clinical improvement of the xerosis following treatment with a urea-containing cream was not accompanied by any significant change in the amino acid content of the SC.

Aged↗
PubMed1989

[The effectiveness of FID-CT (functional image of dynamic CT) for the evaluation of early cerebral ischemia].

A computer program was newly developed to display the ischemic area from the serial dynamic CT scan, namely the functional image of the dynamic CT (FID-CT). The principles of FID-CT are as follows; Seven rapid-sequence dynamic CT scans were taken following a peripheral bolus intravenous injection of 40 ml of iopamidol. As the data from each scan can be separated into three consecutive segments, we obtained 21 images during 44 seconds. Time density curves of each pixel were calculated employing Gamma variate fitting method. Eight functional parameters obtained from this curve were displayed with gray-scale pixel by pixel. These eight images were functional images obtained from dynamic CT. Only three or four minutes were required to complete all the calculations. Twenty-two patients were examined with both FID-CT and 123I-SPECT. In each case, the lesion detected by FID-CT was remarkably consistent with that shown by SPECT. Two representative cases were presented. The authors believe that FID-CT is a very useful diagnostic method in the acute stage of cerebral ischemia because the method can be quickly and easily performed and it discloses the ischemic area with fair certainty.

Aged↗
PubMed1988

Photosensitive psoriasis provoked by a suberythematous dose of ultraviolet-B light.

An unusual case of 'photosensitive psoriasis' is reported. This patient had experienced an exacerbation after sea-bathing, and psoriatic eruptions were observed on the sun-exposed areas of the body. Phototesting with ultraviolet-B (UV-B) revealed his minimal erythema dose to be within normal limits. Three to four weeks after phototesting, however, he developed a psoriatic macule on the area exposed to the suberythematous dose of UV-B. The histologic features of the skin lesion provoked by UV-B irradiation were similar to those of naturally occurring lesions on areas covered by clothes. Moreover, failure to reproduce skin lesions following tape-stripping ruled out a proneness of this patient to develop the Köbner phenomenon nonspecifically.

Adult↗
PubMed1988

[Acute reversible cataract due to nitrocompounds in Japanese quail (Coturnix coturnix japonica)].

The present study was designed to examine the usefulness of the Japanese quail as an experimental model of cataractogenic activity. Chemicals, 2, 6-dibromo-4-nitro-phenol (2, 6-D), 2, 4-dinitroanisole (2, 4-DA), and 2, 4-dinitrophenol (2, 4-D; for the positive control), were administered singly through an oral route to 2-week old male Japanese quails to investigate the reversibility of cataracts. A single administration of 2, 4-D (36 and 43 mg/kg) produced reversible cataract in 14 of 16 animals (87.5%). This cataract was seen 1 or 2 hours after treatment and continued for 1 to 12 hours. Treatment with 2, 6-D (20 and 25 mg/kg) and 2, 4-DA (120 and 150 mg/kg) caused cataracts in 7 of 11 (63.6%) and 8 of 8 surviving animals (100%), respectively. Cataracts produced by 2, 6-D and 2, 4-DA, which were observed from 1 and 2 to 4 hours after the treatment, continued for 6 to 15 and 1 to 13 hours, respectively. Mortalities in the 25 mg/kg group of 2, 6-D, 120 mg/kg and 150 mg/kg group of 2, 4-DA were found in 2 of 5 animals, 1 of 5 animals and 5 of 9 animals, respectively. These results indicate that the Japanese quail is useful as an animal model to evaluate toxicity to the eye and cataractogenesis.

Acute Disease↗
PubMed1986

Immunohistochemical studies on epithelial cells in mixed tumor of the skin.

We performed studies on the lectin-binding pattern in epithelial tumor cell components of 4 cases of mixed tumor of the skin developing on the face in addition to identification of keratin and carcinoembryonic antigen (CEA), compared with those of normal sweat glands. Normal eccrine glands showed specific labelling with Dolichos biflorus agglutinin (DBA) and soybean agglutinin (SBA), whereas none of the studied lectins reacted specifically with normal apocrine glands. In mixed tumors the dark cells, which form the inner layer of the tubuloalveolar and ductal structure, showed the presence of keratin and CEA, as well as of specific sugar structures that bind to DBA and SBA. On the other hand the light cells that form the outer layer of the tubular structures or the solid epithelial cell nests gave only a faint to moderate staining of keratin, and no staining of CEA or lectins. It is probable that the inner dark cells differentiate toward the cells that have the same sugar structures on the cell surface as those of the normal eccrine gland cells, while the outer light cells appear to be immature or in a less differentiated state.

Adult↗
PubMed1985

Subungual melanoma. A clinicopathologic study of 16 Japanese cases.

Melanoma occurs much less frequently among Japanese than among white people. The occurrence of subungual melanoma is uncommon both among white and among Japanese people. However, the authors found 16 subungual melanomas among 86 cases of cutaneous melanoma (19%) at their clinic, quite a high incidence. Of these, 69% (11/16) occurred on the hands and 31% (5/16) on the feet. By far the most common site was the right thumb. Histologic examination revealed that 67% were characterized by acral lentiginous, 50% by superficial spreading, and that there were no nodular melanomas. Most were Clark's Level IV and V at the time of diagnosis. The 5-year survival rate for subungual melanoma was 40%. No statistically significant differences in rate were found between subungual melanoma and volar melanoma. The term "acral" melanoma is recommended to describe the melanomas in the acral regions, because it is descriptive of the regions directly affected.

Actuarial Analysis↗
PubMed1985

Alteration in murine epidermal Langerhans cell population by various UV irradiations: quantitative and morphologic studies on the effects of various wavelengths of monochromatic radiation on Ia-bearing cells.

The present study was undertaken in order to clarify the exact mode of the Langerhans cell (LC) depleting process caused by UV irradiation. Following irradiation with a single dose of various wavelengths of monochromatic UV radiation (UVR), we studied the number of Ia-positive cells in mouse epidermal sheets quantitatively, particularly with regard to dose-response relationship, action spectrum, and time course change. In addition, we studied morphologic alterations of these cells using electron- and immunoelectron microscopy (EM and IEM). We obtained the following results after a single dose of UVB radiation (200 mJ/cm2 of 300 nm) or PUVA (1% of 8-methoxypsoralen (8-MOP) 20 microliter and 1 J/cm2 of 360 nm): (1) EM and IEM showed that while some LCs simply lost their Ia marker without any structural alterations, the majority of the LCs disappeared due to actual cell damage. (2) During an "injury phase," the initial 48 h, and a "recovery phase," lasting from 4-14 days after irradiation, enlargement of the size of remaining Ia-positive LCs occurred. The degree of enlargement was closely related to the degree of reduction in number, suggesting a process compensating for the loss of the LC population. (3) It was found that the recovery rate of LCs after irradiation damage was slower than that of keratinocytes, indicating different cell kinetics between these distinct cell populations in the epidermis, i.e., restoration of LCs after irradiation seems to be achieved at least partially through a repopulation process originating in the bone marrow. Studies with irradiation of various monochromatic wavebands, with or without topical 8-MOP, showed that the action spectrum for Ia-positive cell depletion activity lay within the spectrum shorter than 300 nm for UVR alone, and between 320-380 nm for 8-MOP plus UVR. Since the action spectra were similar to those for keratinocyte damage, i.e., sunburn cell formation, induction of unscheduled DNA synthesis, and to those for UVR-induced erythema, we conclude that common mechanisms underlie these types of tissue damage.

Animals↗
PubMed1985

[Modified env gene in Friend spleen focus forming virus--structure, origin, and its role in leukemogenesis].

Modified env gene or gp55 gene in Spleen Focus Forming Virus, polycythemic strain, K-1 was molecularly cloned and its structure was characterized gp55 is a fusion glycoprotein consisting of N terminal 2/3 of xenotropic virus-related gp70 and C terminal half of F-MuLV p15E. A unique structure at the 3' and of the gp55 gene with 6 base pairs + 1 base pairs insert was identified. Gp55 may be hooked by the lipid bilayer of the cell membrane of the SFFV-intected cells, and additional glycosylation on the cell surface may modify the growth regulation of the cells. Possible origin of SFFV-specific gp55 gene was discussed.

Animals↗
PubMed1984

env-Related leukemogenic genes (gp55 genes) of two closely related polycythemic strains of Friend spleen focus-forming virus possess different recombination points with an endogenous mink cell focus-forming virus env gene.

The unintegrated circular provival DNA of the replication-competent, helper Friend murine leukemia virus (F-MuLV) in a polycythemic strain of Friend leukemia virus complex (FLV, K-1 strain) was molecularly cloned after insertion into the EcoRI site of the plasmid pBR322. The nucleotide sequence of its env gene has been determined. Sequences of this F-MuLV env gene, and the previously reported env-related gene (gp55 gene) of Friend spleen focus-forming virus (SFFV) (K-1 strain) were compared to that of the same gene of the other polycythemic SFFV isolate, SFFV (502), recently reported by Clark and Mak. The gp55 genes of the two SFFV isolates are almost identical to each other and have several common characteristic structures. However, the two gp55 genes are different in that the gp55 gene of SFFV (K-1) has a longer nonecotropic MuLV env sequence than that of SFFV (502). This finding may suggest that each SFFV isolate has been generated independently by recombination between a putative defective variant of F-MuLV and an endogenous mink cell focus-forming virus env sequence.

Amino Acid Sequence↗
PubMed1984

Dynamic changes in epidermal Ia-positive cells in allergic contact sensitivity reactions in mice.

In mice sensitized with trinitrochlorobenzene, serial changes in epidermal Ia-positive cells were studied at various times after challenge. Until 3 days post-challenge, the Ia-positive cells consisted only of dendritic Langerhans cells; their number was decreased but they were significantly enlarged, with extending dendrites. Some Langerhans cells were also found surrounding a hair follicle, extending their dendrites toward the follicle like the spokes of a wheel. From 3 to 9 days after challenge, keratinocytes also began to express Ia antigens in the epidermis in addition to Langerhans cells, whose size diminished. This suggests that there are two phases in the response of the epidermal Ia antigens in contact sensitivity reactions, i.e. an early phase in which enlarged Langerhans cells are the only Ia-positive cells in the epidermis, and a late phase in which keratinocytes take over as the major Ia-positive cells, while Langerhans cells resume their original size. Ia antigen expression on keratinocytes in this late phase probably plays a crucial role in completely eliminating allergens deposited on the keratinocytes.

Animals↗
PubMed1984

Skin metastasis of adenocarcinoma of the urinary bladder.

A papillomatous tumor developed on the skin from the inguinal region to the middle of the right thigh. The histological findings showed tumor cells with papillary formation surrounded with fibrous stroma, and a diagnosis of metastatic adenocarcinoma of the lower gastrointestinal tract was ascertained. Autopsy findings revealed that the cutaneous metastasis was of urinary bladder origin. This paper reports the extreme rarity of metastasis from adenocarcinoma of the urinary bladder to the skin and the peculiar appearance of the cutaneous metastatic lesion.

Adenocarcinoma↗
PubMed1983

Complete nucleotide sequence of the gene for the specific glycoprotein (gp55) of Friend spleen focus-forming virus.

The complete nucleotide sequence of the gene for the specific glycoprotein (gp55) of the polycythemic strain of Friend spleen focus-forming virus (SFFV) was derived from the cloned SFFV DNA intermediate. The gp55 gene is present within 1.4 kilobases of the 5' side of the 3'long terminal repeat sequence. The open reading frame predicts the primary translation product has a total of 409 amino acids with a Mr of 44,752. Comparisons of the deduced amino acid sequence of gp55 with those of the envelope (env) gene products of murine leukemia viruses (MuLVs) revealed that gp55 is composed of three distinct regions. The amino-terminal 80% of the molecule has a high degree of sequence homology with the amino-terminal portion of the gp70 of the Moloney mink cell focus-forming virus (BALB/Mo-MCFV). This portion of the BALB/Mo-MCFV gp70 is known to be coded for by the acquired xenotropic env-like sequence. The sequence of the following 66 amino acids of gp55 is highly homologous to that of the middle portion of the p15E of Moloney MuLV (Mo-MuLV). The sequence of the Carboxyl-terminal 12 amino acids is specific to gp55 and a comparison of the nucleotide sequence showed that this specific amino acid sequence is due to the presence of seven extra nucleotides compared with the sequence of the Mo-MuLV.

Amino Acid Sequence↗
PubMed1983

Quantitative studies on sunburn cell formation in mouse epidermis.

Sunburn cell (SC) formation induced by single or combined doses of monochromatic ultraviolet-A (UV-A), ultraviolet-B (UV-B) and ultraviolet-C (UV-C) was studied quantitatively using mouse epidermal sheet preparations (NaBr split, H & E stain). Results were as follows: 1) Action spectra for SC formation showed that wavelengths shorter than 300 nm were most effective. 2) A significant number of SCs was produced when a high dose of UV-A (360 nm) was administered, and it was estimated that approximately 600 times more UV-A (360 nm) energy was required to produce the same number of SCs as was required with UV-B (300 nm). 3) SC formation by UV-B (300 nm) and UV-C (260 nm) showed a logarithm-like dose-response relationship. 4) Time course studies showed that the maximum number of SCs was attained at 18 hr after UV-C (260 nm) irradiation, at 24 hr after UV-B (300 nm) irradiation and at 30 hr after UV-A (360 nm) irradiation. 5) A high dose of UV-A (360 nm) significantly increased the number of SCs induced by UV-B (300 nm) or UV-C (260 nm) when combined with them.

Animals↗