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Biomedical subjects

T Shirai

Publications and source records attributed to T Shirai.

At least 199 records · Page 11Linked to original sources
PubMed1998

Three-dimensional visualization of ultraviolet-induced DNA damage and its repair in human cell nuclei.

The two major forms of DNA damage produced by 254 nm UV light are cyclobutane pyrimidine dimer (CPD) and (6-4) photoproduct (6-4PP). Both photolesions are repaired in normal human cells by nucleotide excision repair; however, little is known about where CPD or 6-4PP are repaired in relation to the various subnuclear structures. This study aimed to produce a three-dimensional demonstration of UV-induced DNA damage and its repair in human cell nuclei. We first investigated the repair kinetics of CPD and 6-4PP using an enzyme-linked immunosorbent assay with damage-specific monoclonal antibodies in normal human and xeroderma pigmentosum complementation group C cells. We also examined the kinetics of repair DNA synthesis (unscheduled DNA synthesis) using a quantitative immunofluorescence method with anti-5-bromo-2'-deoxyuridine antibodies. We confirmed the normal repair in normal human cells and the impaired repair in xeroderma pigmentosum complementation group C cells. Then, using laser scanning confocal microscopy, we succeeded in forming a three-dimensional visualization of the nuclear localization of CPD, 6-4PP, and unscheduled DNA synthesis in individual human cells. The typical three-dimensional images of photolesions or unscheduled DNA synthesis at various repair times reflected the repair kinetics obtained by enzyme-linked immunosorbent assay or immunofluorescence very well. The important finding is that the punctate, not diffusely spread, nuclear localization of unrepaired 6-4PP was found 2 h after irradiation. Similarly, the focal nuclear localization of unscheduled DNA synthesis was observed during both the first and the second 3 h repair periods. The present results suggest that both 6-4PP and CPD are nonrandomly repaired from nuclei in normal human cells.

Cell Nucleus↗
PubMed1998

Supranuclear melanin caps reduce ultraviolet induced DNA photoproducts in human epidermis.

Melanin can form supranuclear caps in human epidermis, suggesting that intracellular melanin reduces ultraviolet transmission to underlying cell nuclei and inhibits the formation of ultraviolet induced DNA photoproducts. The purpose of this study was to determine the photoprotective effect of epidermal melanin. We irradiated normal human skin explants with ultraviolet B and determined the formation of cyclobutane pyrimidine dimers and (6-4)photoproducts in individual epidermal cells by indirect immunofluorescence and by laser cytometry using monoclonal antibodies specific for cyclobutane dimers or for (6-4)photoproducts. We found that epidermal cells with supranuclear melanin caps had significantly less DNA photoproducts (both types) than epidermal cells without supranuclear melanin caps. Moreover, the protection factor against both types of photolesions correlated with melanin concentration in epidermal cells. These results indicate that melanin reduces ultraviolet induced DNA photoproducts in human epidermis in a concentration dependent manner.

Aged↗
PubMed1998

Neonatal lupus erythematosus: maternal IgG antibodies bind to a recombinant NH2-terminal fusion protein encoded by human alpha-fodrin cDNA.

IgG antibodies to a cleavage product of alpha-fodrin (120 kDa alpha-fodrin) have recently been identified as organ-specific autoantibodies in primary Sjögren's syndrome. In this study, we examined seroreactivity of mothers and infants with neonatal lupus erythematosus (NLE) to a recombinant NH2-terminal protein (120 kDa alpha-fodrin) of human alpha-fodrin. Serum samples were collected during the perinatal period in seven pregnancies of five mothers delivering offspring with NLE. Anti-120 kDa alpha-fodrin antibodies were identified by immunoblotting in six of seven perinatal maternal sera of offspring with NLE: one of two congenital heart block offspring and all five offspring with cutaneous NLE. These antibodies were placentally transmitted to infants. One of the five mothers had primary Sjögren's syndrome, and four were asymptomatic. One asymptomatic mother did not demonstrate anti-120 kDa alpha-fodrin activity at the time of the first delivery of a congenital heart block infant, but was found to be positive at the time of subsequent delivery of a second child with cutaneous NLE. We propose that maternal antibodies to 120 kDa alpha-fodrin may be an additional serologic marker for the risk of NLE in anti-Ro/SS-A positive women.

Autoantibodies↗
PubMed1998

Carcinogenicity of antioxidants BHA, caffeic acid, sesamol, 4-methoxyphenol and catechol at low doses, either alone or in combination, and modulation of their effects in a rat medium-term multi-organ carcinogenesis model.

The carcinogenicity of low dietary levels of the antioxidants butylated hydroxyanisole (BHA), caffeic acid, sesamol, 4-methoxyphenol (4-MP) and catechol, known to target the forestomach or glandular stomach, were examined alone or in combination in a 2-year long-term experiment and their modifying effects assessed in a medium-term multiorgan model. In the carcinogenicity study, groups of 30-31 male F344 rats were treated with 0.4% BHA, 0.4% caffeic acid, 0.4% sesamol, 0.4% 4-MP and 0.16% catechol either alone or in combination for up to 104 weeks and then killed. In the medium-term multi-organ model, groups of 10 to 15 male F344 rats were given diethylnitrosamine (DEN), N-methylnitrosourea (MNU), 1,2-dimethylhydrazine (DMH), N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) and 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN) for a total multiple initiation period of 4 weeks (DMBDD treatment). BHA, caffeic acid, sesamol and 4-MP, each at doses of 0.4% or 0.08%, and catechol at doses of 0.16% or 0.032% were administered in the diet either alone or in combination after completion of the initiation regimen. All surviving animals were killed at the end of week 28, and major organs were examined histopathologically. In the carcinogenicity study, slightly increased incidences of forestomach papillomas were found in the sesamol- (15.8%), caffeic acid- (14.8%), catechol- (3%) and 4-MP- (11.5%) treated groups as compared with basal diet (0%), and a significant increase was observed with the five antioxidants in combination (42.9%, P < 0.001). In a medium-term multiorgan carcinogenesis model, incidences of forestomach papillomas and/or carcinomas were increased in each high dose group, but additive or synergistic effects were not found in the combination group. In the low dose case, the incidence of forestomach papillomas was significantly increased only in the combination group. With regard to other organs, the incidence of colon tumors was significantly decreased only in the high dose combination group. The results indicate that even at low dose levels phenolic compounds can exert additive/synergistic effect on carcinogenesis.

Animals↗
PubMed1998

Lack of promoting effects of the electromagnetic near-field used for cellular phones (929.2 MHz) on rat liver carcinogenesis in a medium-term liver bioassay.

The possible cancer promotion potential of local exposure to a pulse modulated 929.2 MHz electromagnetic near-field on chemically-initiated rat liver carcinogenesis was investigated employing a medium-term bioassay. A 929.2-MHz electromagnetic near-field of time division multiple access (TDMA) signal for PDC (Personal Digital Cellular, Japanese cellular telephone standard) system was directed to rats through a quarter-wavelength monopole antenna. Maximum local specific absorption rates (SARs) on temporal average were 7.2-6.6 W/kg within the whole body and 2.0-1.7 W/kg within the liver, which was the target organ. The whole-body average SARs on temporal average were 0.80-0.58 W/kg. Temporal peak SARs had three times these values due to the duty ratio of the PDC signal. Exposure was for 90 min a day, 5 days a week, over 6 weeks. The exposure apparatus was specially designed for this experiment, to allow exposure of the lateral mid-section of the rat body to the electromagnetic near-field. Male F344 rats, 6 week-old, were initially (at week 0) given a single dose of diethylnitrosamine (DEN, 200 mg/kg body wt, i.p.). At 2 weeks later, exposure (48 rats) or sham-exposure (48 rats) was started. The exposure of electromagnetic near-fields was performed using the exposure apparatus mentioned above. At week 3, all rats were subjected to a 2/3 partial hepatectomy. At week 8 (i.e. after 6 weeks exposure or sham-exposure), the experiment was terminated and all rats were killed. Carcinogenic potential was scored by comparing the numbers and areas of the induced glutathione S-transferase placental form (GST-P) positive foci in the livers of the exposed and sham-exposed rats. A further group of 24 animals, given only DEN and partial hepatectomy, served as the controls. The numbers (no./cm2) of GST-P positive foci were 4.61 +/- 1.77, 5.21 +/- 1.92 (P < 0.05, versus control) and 4.09 +/- 1.47 and the areas (mm2/cm2) were 0.30 +/- 0.16, 0.36 +/- 0.21 and 0.28 +/- 0.15, for the exposed, sham-exposed and control groups, respectively. There were no significant differences between the exposed and sham-exposed groups. These findings clearly indicated that local body exposure to a 929.2-MHz field, modulated in a PDC waveform, has no significant effect on rat liver carcinogenesis under the experimental conditions employed.

Adrenocorticotropic Hormone↗
PubMed1998

Presence of a threshold for promoting effects of phenobarbital on diethylnitrosamine-induced hepatic foci in the rat.

The dose dependence of the hepatopromoting effects of phenobarbital (PB) was investigated in a rat liver medium-term bioassay (Ito test) to elucidate a practical threshold level. F344 rats were given a single i.p. injection of diethylnitrosamine (200 mg/kg body wt) and subjected to two-thirds partial hepatectomy at week 3. Commencing 2 weeks from the start, PB at doses of 0, 1, 2, 4, 7.5, 15 or 500 p.p.m. in experiment 1 and 0, 0.01, 0.1 or 0.5 p.p.m. in experiment 2 were fed to the rats for 6 weeks. Experiment 3 was conducted to confirm previous data using the same medium-term bioassay, with PB at doses of 0, 1, 2, 4, 7.5, 15, 30, 60, 125, 250 or 500 p.p.m. fed to the rats. All surviving animals were killed at week 8 in these experiments and their livers were immunohistochemically examined for expression of glutathione S-transferase placental form (GST-P). Quantitative values for GST-P-positive foci in the liver were increased dose dependently in rats given 60-500 p.p.m. PB. However, those for doses in the range 1-7.5 p.p.m. demonstrated a decrease as compared with the control group (0 p.p.m.), with significant differences observed for 1 and 2 p.p.m.. The results for 15-30 and 0.01-0.5 p.p.m. were comparable with the control values. Examination of transforming growth factor-alpha (TGF-alpha)-positive foci also produced similar results to those for GST-P in experiment 1. Immunohistochemical staining of TGF-alpha and GST-P using serial liver sections demonstrated that the TGF-alpha-positive foci comprised a sub-population of the GST-P-positive lesions, being approximately 1/8-1/10th as common in livers of animals treated with PB. TGF-alpha-positive foci were almost always negative on immunostaining for TGF-beta. Western blotting for proteins CYP2B1, 2C6 and 3A2 revealed a good correlation between changes in GST-P-positive foci and CYP3A2 protein expression. The finding of inhibition effects at low doses of PB confirms the presence of a threshold level for promoting effects by PB on liver carcinogenesis in rats.

Animals↗
PubMed1998

Dissection of the effects of tumor necrosis factor-alpha and class II gene polymorphisms within the MHC on murine systemic lupus erythematosus (SLE).

Gene(s) in the MHC of the NZW strain (H-2z) up-regulate(s) systemic lupus erythematosus (SLE) in (NZB x NZW) F1 mice. So far, two plausible mechanisms have been implicated: (i) unique mixed haplotype class II molecules formed in the F1 mice act as a restriction element for self-reactive T cells and (ii) a unique polymorphism in the H-2-linked NZW tumor necrosis factor (TNF)-alpha allele which down-regulates TNF-alpha is contributory. Because of the difficulty in dissecting these alleles within the H-2 complex, it has not been determined which is indeed the case. We addressed this issue by establishing three different H-2-congenic (NZB x NZW) F1 mice bearing distinct haplotypes at class II and TNF-alpha regions, i.e. (NZB x NZW) F1 (H-2d/z:A(d/u)E(d/u)TNF(d/z)), (NZB x NZW.PL) F1 (H-2(d/u):A(d/u)E(d/u)TNF(d/d)) and (NZB x NZW.H-2d) F1 (H-2(d/d):A(d/d)E(d/d)TNF(d/d)). Among these, only (NZB x NZW) F1 produced a markedly lower level of TNF-alpha, due to the unique NZW TNF-alpha allele (TNF(z)). Studies of anti-DNA antibodies and lupus nephritis revealed that, compared to (NZB x NZW) F1, the disease of (NZB x NZW.H-2d) F1 was markedly reduced. In (NZB x NZW.PL) F1, the onset of renal disease was significantly delayed, while the extent of proteinuria and renal histopathology in individuals that had developed the disease was comparable to that seen in (NZB x NZW) F1. It seems likely that both class II and TNF-alpha gene polymorphisms are functioning as H-2-linked predisposing genetic elements, and that the TNF-alpha polymorphism acts to modulate an initial process of the renal disease.

Animals↗
PubMed1998

Deletion of signaling molecule genes resembling the cytoplasmic domain of Igbeta in autoimmune-prone mice.

The P8.6 gene is encoded upstream of the mouse TCR Valpha1 gene in the anti-sense strand and its gene product contains the proline-rich region and tyrosine-isoleucine (Y-I) motif, which are consensus sequences for the SH2 and SH3 binding motifs respectively. It was found that this protein is highly homologous to Igbeta. We also found that the P8.6 protein associates with a 170 kDa phosphorylated protein in vivo. To examine the polymorphism of the P8.6 gene, we carried out a single-strand conformation polymorphism analysis and found that the P8.6 gene comprises a family of at least 13 independent genes arising from single or multiple mutations. The mutated P8.6 gene with the Y-L motif was deleted, especially in NZW and BXSB mice, whereas normal BALB/c mice have a P8.6 gene bearing both the Y-I and Y-L motifs, suggesting a dysregulation in signaling through the B cell receptor or TCR in these two autoimmune mice. Functional analysis using transfectant cells carrying P8.6-1 (Y-I motif) and P8.6-3 (Y-L motif) clearly demonstrated that P8.6-3 gene inhibited the signal transduction upon the stimulation of ionomycin and cell growth. The TANYSNI sequence has been proposed as the immunoreceptor tyrosine-based inhibitory motif, this motif is replaced by AANYSNI in the NZW mice. In conclusion, some P8.6 are deleted in particular autoimmune-prone mice.

Amino Acid Sequence↗
PubMed1998

Prevention by synthetic phenolic antioxidants of 2-amino-3, 8-dimethylimidazo[4,5-f]quinoxaline (MeIQx)- or activated MeIQx-induced mutagenesis and MeIQx-induced rat hepatocarcinogenesis, and role of antioxidant activity in the prevention of carcinogenesis.

Effects of synthetic phenolic antioxidants 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ) and propyl gallate (PG) on 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx)- or activated MeIQx-induced mutagenesis and rat hepatocarcinogenesis were compared, and the association between antioxidative activity and inhibition of carcinogenesis was examined. When the antimutagenic activity of five antioxidants against MeIQx- or activated MeIQx-induced mutagenesis was compared in the Ames assay using the Salmonella strain TA 98, HTHQ showed the greatest effect, followed by BHA, BHT, PG and TBHQ, in that order. In a rat hepatocarcinogenesis study, 6-week-old male F344 rats were given a single i.p. injection of 200 mg/kg bw of diethylnitrosamine (DEN) and starting 2 weeks later, groups of 15 animals received a diet containing 0.03% MeIQx alone, MeIQx together with each antioxidant at a dietary dose of 0.25%, each antioxidant alone, or basal diet alone for 6 weeks. Three weeks after the DEN injection, animals were subjected to 2/3 partial hepatectomy. Liver tissues obtained at partial hepatectomy were processed for the measurement of 8-hydroxydeoxyguanine (8-OHdG) and lipid peroxidation. The average number and areas of glutathione S-transferase placental form (GST-P) positive foci were increased by the treatment with MeIQx (27.2 +/- 6.5 per cm2 and 3.17 +/- 0.96 mm2/cm2, respectively). A significant decrease in these parameters was found with the simultaneous antioxidant treatment, HTHQ demonstrating the greatest effect, followed by BHA, BHT and TBHQ, and PG. Without MeIQx, a weak increase in the number of foci was observed in the BHT treatment case. Examination of 8-OHdG levels in liver DNA, as well as malondialdehyde (MDA) and 4-hydroxyalkenals, did not reveal any inter-group variation. These results indicate that antimutagenic activity of antioxidants against MeIQx roughly parallels their anticarcinogenic activity, with HTHQ as the most powerful chemopreventor, but that oxidative stress and antioxidative activity may not be responsible for MeIQx-induced hepatocarcinogenesis and its inhibition, respectively.

Animals↗
PubMed1998

Two cases of unilateral axillary Paget's disease.

We herein report two cases of unilateral axillary Paget's disease. Extramammary Paget's disease commonly occurs in the anogenital area. Unilateral axillary occurrence is relatively rare. One defect was reconstructed with a pedicled scapular flap, and the other was reconstructed with split-skin graft after excision of the tumor. No recurrence was seen in either patient three years postoperatively. However, although the patient who had been reconstructed with a pedicled flap recovered uneventfully, the other patient, who had been reconstructed with a split-skin graft, suffered from axillary contracture due to the shrinkage of the grafted skin after surgery. A skin graft requires fixation for a long period to prevent shrinkage, which causes axillary contracture. Therefore, from the viewpoint of quality of life, reconstruction using flaps is recommended for axillary lesions.

Aged↗
PubMed1998

A case of dystrophic epidermolysis bullosa: surgical treatment for hand contracture using abdominal skin flap.

The patient was a 15-year-old male. Since birth, he has suffered from recurrent blistering, especially on the extremities. Histology and electron microscopic finding of the cutaneous lesions were compatible with those of dystrophic epidermolysis bullosa. Contracture and mobility limitation of the hands had gradually deteriorated. Prior to the admission to our clinic, both hands' contracture had been surgically treated 4 times in another hospital; however, after treatment with skin grafting, hand contracture recurred each time within one year. This time, surgical treatment was carried out for his left hand contracture using an abdominal skin flap under local anesthesia. In comparison with the free skin graft the abdominal skin flap improved hand contracture for a longer time. Abdominal skin flap is recommended as a method for the treatment of hand contracture of patients with dystrophic epidermolysis bullosa.

Abdomen↗
PubMed1998

Primary Sjögren's syndrome followed by chronic myelogenous leukemia: a case report with a ten year history.

We describe a female patient with primary Sjögren's syndrome who subsequently developed chronic myelogenous leukemia. The patient received a bone marrow transplant (BMT) from a genotypically HLA-identical brother after pre-transplant preparation with busulfan and cyclophosphamide. Eighteen weeks later, cutaneous and mucosal chronic graft-versus-host disease developed, followed by death 11 months after transplantation. Anti-Ro/SS-A antibodies disappeared within 6 months post-BMT, but antinuclear antibodies remained positive through the post-transplant course.

Adult↗
PubMed1998

Bullous pemphigoid associated with Shy-Drager syndrome.

We report a patient with Shy-Drager syndrome who developed multiple tense blisters mainly on the extremities. Circulating anti-basement membrane zone autoantibodies were detected by the indirect immunofluorescence method. Immunoblot analysis using normal human epidermal extracts demonstrated that this patient's serum reacted only with 230 kD bullous pemphigoid antigen (BPAG1). Concerning the pathoetiology of the association of bullous pemphigoid and Shy-Drager syndrome, we discuss a sequence similarity between BPAG1 and dystonin, a candidate gene for dystonia musculorum.

Autoantibodies↗
PubMed1998

Linear IgA bullous dermatosis with circulating IgG autoantibodies to the 230 kD epidermal antigen.

The patient was a 54-year-old woman with wide-spread bullous lesions on her trunk and oral mucosa. Histologic examination revealed a subepidermal blister with infiltration of neutrophils and eosinophils. Direct immunofluorescence showed an exclusively IgA deposition at the basement membrane zone (BMZ). Indirect immunofluorescence showed that the blister fluid, but not the serum, contained IgG antibodies against the BMZ antigen on the epidermal side of salt-split skin. Using immunoblot analysis with normal human epidermal extracts, both serum and blister fluid reacted with the 230 kD epidermal antigen. Using colloidal gold and direct immunoelectron microscopy, IgA deposition was detected in the lamina lucida. Clinically, the skin lesions responded well to dapsone. We diagnosed this case as linear IgA bullous dermatosis (LABD) with IgG class circulating autoantibodies against the epidermal 230 kD antigen. These antibodies were considered to be secondary to the damage to the epidermal basal keratinocyte in this case.

Autoantigens↗
PubMed1998

A case of pustular ulcerative dermatosis of the scalp associated with ulcerative skin lesions on the scrotum.

A 79-year-old man developed pustules, erosions, and ulcer with severe pain on the parietal regions of the scalp and the scrotum. In another hospital, mycobacterium was detected from the pustules of the scalp at Gaffky scale 1, and this patient was referred to our clinic. In our hospital, repeated cultures of the pus from the skin lesions of the scalp were negative for mycobacterium. Biopsy specimens obtained from the skin lesions on the scalp disclosed ulcerative granulation with infiltration of inflammatory cells. Antibiotics and antituberculotic agents were ineffective. In contrast, the ulcerative skin lesions on the scalp and scrotum responded well to topical and systemic glucocorticosteroids. Although this patient developed pustular ulcerative skin lesions not only on the scalp but also on the scrotum, we considered this case to be pustular ulcerative dermatosis of the scalp developing ulcerative skin lesions on the scrotum.

Administration, Topical↗
PubMed1998

A case of nonscarring inflammatory epidermolysis bullosa acquisita: characterization of IgG autoantibodies by immunofluorescence, immunoblotting and immunogold electron microscopy.

We report a case of nonscarring inflammatory epidermolysis bullosa acquisita in a 59-year-old Japanese woman. She developed blisters and erosions on her lip, trunk and extremities. Sodium aurothiomalate was effective for the skin lesions. The patient had been free from bullous skin lesions for the last 13 years and had shown no scarring. Indirect immunofluorescence (IF) study on 1 M NaCl-split skin revealed IgG autoantibodies against the dermal side of the split skin. Immunoblotting using normal human dermal extracts disclosed IgG autoantibodies reactive with the 290 and 145 kD antigens. Circulating IgG autoantibodies were deposited on the lamina densa by immunoelectron microscopy. IF mapping using several antibodies for the components of the basement membrane zone revealed blister formation at the lamina densa. These results suggest that the cleavage at the lamina lucida does not necessarily exclude the diagnosis of EBA and that the definite diagnosis of EBA should be confirmed by immunoblotting or immunoelectron microscopic study.

Antirheumatic Agents↗
PubMed1998

Effect of nonenzymatic glycosylation on the titers of circulating autoantibodies in pemphigus and pemphigoid.

Hyperglycemia is observed in some patients with autoimmune bullous diseases complicated by diabetes mellitus or treated with systemic corticosteroids. High concentrations of glucose can react with various proteins and change their structural and functional properties. We previously reported that nonenzymatic glycosylation of antibody can impair antigen-antibody binding. We ascertained whether glycosylation of autoantibody decreases the autoantibody titer by examining 30 sera from patients with pemphigus and pemphigoid. Nonenzymatic glycosylation in the physiological range was induced by incubation of sera with 1650 mM D-glucose at 4 degrees C for 7 days. The titers of sera were determined by indirect immunofluorescence (IIF). In all cases, the immunofluorescence intensity of glycosylated sera was weaker than that of nonglycosylated sera. Glycosylated sera showed a lower antibody titer by 1 doubling dilution in 18 out of 30 cases, compared with nonglycosylated sera. The ten BP patients' sera were also analyzed by immunoblotting for reactivity with the BP180-GST fusion proteins, S delta 1 and 4575. All BP sera reacted with S delta 1, and 5 out of 10 BP sera reacted with both S delta 1 and 4575. In all the sera that reacted only with S delta 1, the glycosylated sera showed a 1 doubling dilution decrease in autoantibody titer. Interestingly, in 4 out of 5 sera that reacted with both S delta 1 and 4575, there were no differences in the antibody titer between glycosylated and nonglycosylated sera. These results indicate the possibility of a false decrease in autoantibody titers of sera from patients with autoimmune bullous diseases complicated with hyperglycemia. Although the false decrease in titers of autoantibodies induced by nonenzymatic glycosylation is not dramatic, it must be considered in order not to underestimate the disease activity of pemphigus in such cases.

Autoantibodies↗