Search PubMed⌕ Search

Biomedical subjects

H Yagi

Publications and source records attributed to H Yagi.

At least 199 records · Page 11Linked to original sources
PubMed1993

Dose-dependent differences in the profile of mutations induced by (+)-7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene in the coding region of the hypoxanthine (guanine) phosphoribosyltransferase gene in Chinese hamster V-79 cells.

Chinese hamster V-79 cells were exposed to a high dose (0.30-0.48 microM; 32% cell survival), an intermediate dose (0.04-0.10 microM; 100% cell survival) or a low dose (0.01-0.02 microM; 97% cell survival) of (+)-7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene [(+)-BPDE] which is the ultimate carcinogenic metabolite of benzo(a)pyrene. The mutation frequency for cells treated with dimethyl sulfoxide vehicle or with low, intermediate or high dose of (+)-BPDE were 1, 10, 52 or 514 8-azaguanine-resistant colonies/10(5) survivors, respectively. Independent 8-azaguanine-resistant clones were isolated, and complementary DNAs were prepared by reverse transcription. The coding region of the hypoxanthine (guanine) phosphoribosyltransferase (HPRT) gene was amplified by the polymerase chain reaction and sequenced. Altogether, 368 (+)-BPDE-induced mutant clones were examined. At all doses, base substitutions were the most prevalent mutations observed (about 72% of the mutant clones), followed by exon deletions (about 26% of the mutant clones) and frame-shift mutations (about 6% of the mutant clones). At the high cytotoxic dose, 7 of 120 base substitutions occurred at AT base pairs (6%) and 113 at GC base pairs (94%). At the intermediate noncytotoxic dose, 20 of 82 base substitutions occurred at AT base pairs (24%) and 62 at GC base pairs (76%). At the low noncytotoxic dose, 27 of 76 base substitutions were at AT base pairs (36%) and 49 were at GC base pairs (64%). The results indicated that decreasing the dose of (+)-BPDE decreased the proportion of mutations at GC base pairs and increased the proportion of mutations at AT base pairs. At the dose of (+)-BPDE was decreased, there was a dose-dependent decrease in the proportion of GC-->TA transversions (from 69% to 42% of the base substitutions) and a dose-dependent increase in the proportion of AT-->CG transversions (from 1% to 25% of the base substitutions). The data also indicated dose-dependent differences in (+)-BPDE-induced exon deletions and hot spots for base substitutions at GC and AT base pairs. Although more than 99% of the (+)-BPDE-induced mutations at guanine occurred on the nontranscribed strand of DNA, (+)-BPDE-induced mutations at adenine occurred on both the transcribed and nontranscribed strands. The ratio of mutations at adenine on the transcribed strand to mutations at adenine on the nontranscribed strand was 35:19 in (+)-BPDE-treated V-79 cells.(ABSTRACT TRUNCATED AT 400 WORDS)

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1993

Transfer of autoimmune diabetes from diabetic NOD mice to NOD athymic nude mice: the roles of T cell subsets in the pathogenesis.

The NOD mouse, which spontaneously develops insulitis and overt diabetes, is a model of autoimmune type I diabetes mellitus. To analyze of the roles of CD4+ and CD8+ T cells in the pathogenesis of this mouse, we have been doing a series of studies on the induction of insulitis and diabetes in NOD athymic nude mice by means of T cell transfer. To complement our previous study dealing with the induction of insulitis and cyclophosphamide-induced diabetes in recipients that had been reconstituted with each T cell subset derived from the nondiabetic mice, the present study was conducted to observe the transfer of spontaneous diabetes by injecting T cells harvested from diabetic mice. Any possible in vivo increase in the contaminating T cell subset was prevented by injecting the antibody homologous to it. Transfer of untreated or complement-treated splenic lymphocytes of diabetic mice containing both T cell subsets induced spontaneous diabetes 30 to 58 days after the cell transfer as well as insulitis, while spleen cells from nondiabetic mice rarely produced diabetes. On the other hand, transfer of either CD4+ cell-depleted or CD8+ cell-depleted splenic lymphocytes of diabetic mice did not cause diabetes at least up to 60 days after the cell transfer. Also, transfer of only the CD4+ T cell-depleted fraction did not cause insulitis. In contrast, transfer of only the CD8+ T cell-depleted fraction induced insulitis in all the recipients. However, insulitis was less potent in this group of mice than in the diabetic recipients given both subsets: only a low insulitis score was obtained and a number of beta-cells remained alive despite the insulitis in mice given the CD8+ T cell-depleted fraction, whereas islet damage was very severe and insulin-secreting beta-cells were no longer detected in the diabetic mice. Thus, the present results agree with the previous ones concerning transfer of diabetes, with the aid of cyclophosphamide treatment, by T cells of nondiabetic mouse origin. Consideration of our results together with earlier findings led to the conclusion that CD4+ T cells are primarily responsible for insulitis and that CD8+ T cells migrate into islets and are differentiated into mature killer cells against beta-cells with the aid of CD4+ T cells in both spontaneous and cyclophosphamide-induced diabetes.

Animals↗
PubMed1993

Sequence specificity in the interaction of the four stereoisomeric benzo[c]phenanthrene dihydrodiol epoxides with the supF gene.

The shuttle vector pS189 was treated with each of the four configurational isomers of benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxide, and the modified DNA was used as a template in a polymerase arrest assay examining the supF gene. Sites at which polymerase (Sequenase, version 2.0) progress along the template was blocked were presumed to be at or near sites of adduct formation. The polymerase arrest sites were compared with recently reported mutation hotspots induced by these agents in this gene (Bigger et al., Proc. Natl. Acad. Sci. USA, 89: 368-372, 1992). For 31 of 32 mutation hotspots, a polymerase arrest band was present at or 1 or 2 nucleotides 3'- to that site, indicating that adduct formation tended to be associated with mutation hotspots. However, the arrest bands near mutation hotspots were not particularly prominent in all cases, and there were many sites of substantial polymerase arrest that were not in the vicinity of mutation hotspots. Thus, factors in addition to chemical selectivity must play key roles in determining sites of mutation.

Base Sequence↗
PubMed1993

Involvement of thromboxane A2 in bronchial hyperresponsiveness but not lung inflammation induced by bacterial lipopolysaccharide in guinea pigs.

We examined both a possible association of bronchial hyperresponsiveness with lung inflammatory responses and the role of thromboxane (Tx) A2 in these responses after lipopolysaccharide (LPS) exposure in guinea pigs treated with metyrapone, a cortisol synthesis inhibitor. The increase in bronchial responsiveness to i.v. acetylcholine was transient, with a peak at 2 h after LPS exposure, which was associated with increases in TxB2 and tumor necrosis factor in bronchoalveolar lavage (BAL) fluid. However, the levels of 6-keto-prostaglandin (PG) F1 alpha, interleukin-1 and interleukin-6 in BAL fluid, and the influx of leukocytes in airway and pulmonary edema were not associated with bronchial hyperresponsiveness. Oral administration of S-1452, a selective TxA2 receptor antagonist, markedly suppressed bronchial hyperresponsiveness without affecting cellular responses, pulmonary edema and production of PGs and cytokines. These findings suggest that LPS-induced bronchial hyperresponsiveness is dependent on secondarily generated TxA2, which appears to be independent of lung inflammation.

Animals↗
PubMed1993

Newborn rabbit gastric smooth muscle cell culture: EGF and TGF-alpha are potent mitogens.

Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) are two in a family of growth-promoting peptides for many gastrointestinal epithelia. This study was designed to assess their mitogenic effect on cultured gastric myocytes and to characterize specific EGF receptors on these cells. Single myocytes were isolated from newborn rabbit gastric fundus and placed into tissue culture. The composition of the culture at confluence as assessed by immunostaining with smooth muscle actin-specific monoclonal antibody (CGA7) was > 95% myocytes. To assess the effect of putative growth factors, freshly isolated myocytes were incubated in Dulbecco's modified Eagle's (DME) medium containing 1% fetal bovine serum in the presence or absence of growth factors. After 6 days, cells were incubated in serum-free medium with [3H]thymidine (1 microCi/ml) in the continued presence or absence of growth factors. After 24 h, EGF and TGF-alpha but not insulin-like growth factor I (IGF-I) induced a dose-dependent increase in [3H]thymidine incorporation. Ten nanomolar EGF or TGF-alpha increased [3H]thymidine incorporation more than sixfold over control. EGF was more potent than was TGF-alpha, with apparent median effective dose (ED50) values of 64 +/- 14 pM and 166 +/- 62 pM (p < 0.05), respectively. EGF bound to cultured myocytes with Kd = 7.6 +/- 1.8 nM and Bmax = 27 +/- 11 pmol/mg DNA or 440,000 receptors/cell. TGF-alpha competed for binding at these receptors. Although IGF-I did not stimulate thymidine incorporation, specific high-affinity receptors for IGF-I were detected on gastric myocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Inhibitory effect of melanin pigment on sensitization and elicitation of murine contact photosensitivity: mechanism of low responsiveness in C57BL/10 background mice.

We have shown that murine contact photosensitivity (CPS) to 3,3',4',5-tetrachlorosalicylanilide (TCSA) is genetically controlled mainly by the major histocompatibility complex. The H-2b,d haplotypes are closely associated with high responders, whereas mice with the H-2k are non-responders. Irrespective of their H-2 haplotypes, the C57BL/10 (B10) background strains, including B10, B10.D2, B10.A, and B10.BR, possessing black fur color, were low or nonresponders in CPS to TCSA. In B10 mice, however, high-sensitivity responses were induced when subcutaneous inoculation of epidermal cells (ECs) photomodified in vitro with TCSA was used for both immunization and challenge, suggesting that the epicutaneous route for induction and elicitation is defective in B10 background mice. F1 mice obtained by crossing high-responder BALB/c and low-responder B10 mice, possessing agouti fur color, were non-responders of CPS. The magnitude of CPS in the F2 mice derived from F1 (BALB/c X B10) siblings varied from low to high. When these F2 mice were divided into five groups with regard to fur color, the magnitude of reaction was correlated with the fur color and there was inverse relationship between the magnitude of CPS and the amount of melanin pigment in earlobe ECs. Furthermore, the in vivo formation of TCSA-EC photoadducts was negatively correlated to the melanin amount in earlobes. These observations suggested that the failure in CPS of the B10 background mice stems from inability of in vivo photocoupling of TCSA to ECs, presumably due to absorption of ultraviolet radiation by melanin pigment.

Animals↗
PubMed1993

A case of Johanson-Blizzard syndrome complicated by diabetes mellitus.

We report a girl with Johanson-Blizzard syndrome complicated by diabetes mellitus. She presented several characteristic malformations, such as aplasia of the alae nasi, deafness, dwarfism, absence of permanent teeth and malabsorption caused by disturbance of pancreatic exocrine function. At 11 years of age, glycosuria was detected at a routine outpatient examination. Repeated oral glucose tests showed a slowly progressive decline of insulin secretion and elevated blood glucose levels. The responsive secretion of insulin to glucagon or arginine loading was also low. The blood level of HbAlc was elevated over 9%. Based on these findings, insulin therapy was started when the patient was 13 years old. Our case suggests that diabetes mellitus might be considered as one of complications of Johanson-Blizzard syndrome.

Abnormalities, Multiple↗
PubMed1993

Posterior lobe of the pituitary in diabetes insipidus: dynamic MR imaging.

Magnetic resonance (MR) imaging was performed in 10 subjects: four with central idiopathic diabetes insipidus (DI), two with nephrogenic DI, and four with normal pituitary glands. Characteristics high intensity of the posterior pituitary lobe was seen in all four control subjects and one case of nephrogenic DI. However, it was undetectable in all four cases of central idiopathic DI and one case of nephrogenic DI. Peak contrast enhancement of the posterior lobe occurred within 30 seconds after injection of gadopentetate dimeglumine in control subjects and in both cases of nephrogenic DI and at 30-60 seconds in one case of mild partial idiopathic DI. In contrast, no or faint early enhancement of the posterior pituitary lobe was observed in two cases of complete and one case of partial central DI. In patients with central DI, MR imaging reveals delayed enhancement of the posterior pituitary lobe compared with the early enhancement seen in subjects without central DI.

Adolescent↗
PubMed1993

Transport of triiodothyronine by erythrocytes from premature and term infants.

To analyze hypothyroxinemia in low birth weight (LBW) infants, the initial uptake of T3 into erythrocytes from term and premature infants was measured. Thirty-eight infants and 18 prepubertal children as controls were subjected in this study. The infants were divided into group 1 (premature infants; below 2,500 g, n = 12) and group 2 (term infants; 2,501-3,500 g, n = 26). Infants with LBW for gestational age were excluded from this study. Vmax for group 1 (mean +/- SE, 6.4 +/- 0.5 pmol/min/10(8) cells), having low thyroid hormone levels, was significantly less than in group 2 (9.0 +/- 0.7 pmol/min/10(8) cells; p < 0.05). Mean Vmax for both groups exceeded normal controls (3.9 +/- 0.3 pmol/min/10(8) cells; p < 0.01). Km in the perinatal period varied widely and was essentially the same as in the normal controls. These findings indicate that T3 uptake by erythrocytes of newborns may possibly be high regardless of maturation stage and blood levels of thyroid hormones may be reflected not by change in the affinity of the transport system but by that in the number of membrane carriers.

Biological Transport↗
PubMed1993

A new point mutation in the deoxyribonucleic acid-binding domain of the vitamin D receptor in a kindred with hereditary 1,25-dihydroxyvitamin D-resistant rickets.

Hereditary 1,25-dihydroxyvitamin D [1,25-(OH)2D]-resistant rickets (HVDRR) is a rare disorder characterized by rickets, alopecia, hypocalcemia, secondary hyperparathyroidism, and normal or elevated serum 1,25-dihydroxyvitamin D levels. We describe a patient with typical clinical characteristics of HVDRR, except that elevated levels of serum phosphorus were present coincident with increased levels of serum intact PTH. The patient was treated with high dose calcium infusion after an ineffective treatment with 1 alpha-hydroxyvitamin D3; serum calcium and phosphorus as well as intact PTH and alkaline phosphatase levels were normalized. Evaluation of phytohemagglutinin-activated lymphocytes derived from this patient revealed that 1,25-(OH)2D3 was unable to inhibit thymidine incooperation, a result that contrasts with the capacity of 1,25-(OH)2D3 to inhibit uptake into normal activated lymphocytes. 1,25-(OH)2D3 did not induce human osteocalcin promoter activity after transfection of this DNA linked to a reporter gene into patient cells. Cointroduction of a human vitamin D receptor (VDR) cDNA expression vector with the reporter plasmid, however, restored the hormone response. Evaluation of extracts from the patient cells for VDR DNA binding revealed a defect in DNA binding. Analysis of genomic DNA from the patient's cells by PCR confirmed the presence of a point mutation in exon 2 of the VDR. This exon directs synthesis of a portion of the DNA-binding domain of the receptor. We conclude that the genetic basis for 1,25-(OH)2D3 resistance in this kindred with VDR-positive HVDRR is due to a single base mutation in the VDR that leads to production of a receptor unable to interact appropriately with DNA.

Binding Sites↗
PubMed1993

Relationship between serum levels of methylguanidine and glycemic control in IDDM children.

OBJECTIVE: To examine the serum levels of methylguanidine in IDDM children and compare them with markers for glycemic control. Reports have indicated that active oxygen, which damages various tissues, increases in diabetes mellitus. The increase of active oxygen is one of the risk factors for diabetic complications. The synthesis of methylguanidine, a metabolic product of guanidine, is mainly regulated by active oxygen. RESEARCH DESIGN AND METHODS: Forty-eight children with IDDM (mean age 13.3 yr) and 17 age-matched nondiabetic control subjects were studied. Diabetic children were divided into a well-controlled group (HbA1c < 8%, n = 24) and a poorly controlled group (HbA1c > 8%, n = 24). Serum concentrations of methylguanidine were measured by enzymatic assay. RESULTS: Levels of methylguanidine in the poorly controlled group (1.31 +/- 0.08 microM) were significantly higher than those in both the well-controlled group (0.85 +/- 0.08 microM) and the control group (0.59 +/- 0.11 microM), respectively (P < 0.01). Methylguanidine levels showed a positive correlation with the levels of HbA1c (P < 0.01) or fructosamine (P < 0.01). No significant correlations were noted between methylguanidine levels and age, sex, duration of diabetes, or insulin dose. CONCLUSIONS: Our data indicate that the levels of methylguanidine in IDDM children might be affected by glycemic control and that the determination of serum methylguanidine levels could be a useful test for evaluating the state of diabetic control.

Biomarkers↗
PubMed1993

[Extracapsular tumor invasion in renal cell carcinoma: with special reference to limitation of surgical enucleation].

To elucidate the feasibility of surgical enucleation, the incidence of extracapsular tumor invasion in 30 cases of renal cell carcinoma with a diameter less than 5 cm was examined, based on the classification of extracapsular tumor invasion into three patterns, namely microinvasion, nodular invasion, and daughter tumors. Of the 30 cases of renal cell carcinoma, 22 cases (73%) revealed extracapsular tumor invasion. And the incidence of microinvasion, nodular invasion and daughter tumors was 7 cases (23%), 9 cases (30%) and 6 cases (20%), respectively. But the incidence of these three patterns of extracapsular tumor invasion correlated neither with the size of renal cell carcinoma nor with pT classification. There was a tendency for extracapsular tumor invasion to occur near the renal hilar site of the renal cell carcinoma, where the tumor vessels were rich, penetrated and twined around the tumor capsule, resulting in the disruption of the tumor capsule. These three patterns of invasion was located within 1 cm in distance from the tumor capsules in all cases. In conclusion, because of limited radicality achieved by tumor enucleation even in the case of pT1, partial nephrectomy was recommended in the presence of a normal contralateral kidney.

Carcinoma, Renal Cell↗
PubMed1993

[Preoperative embolization using absolute ethanol for renal cell carcinoma--including the questionnaire survey in Japan].

The usefulness of transvascular embolization before radical nephrectomy using absolute ethanol was studied in thirty-two cases with renal cell carcinoma, among them, 30 cases received radical nephrectomy one day after transvascular embolization. And a nation wide questionnaire survey regarding the embolization was also reported. These results were as follows: 1. The infarcted areas were very extensive and among 28 cases examined, 26 cases showed more than 75% of infarct in the whole area of the cortex. 2. Among 32 cases, 22 cases complained of no pain after the embolization using absolute ethanol only by the preventive epidural administration of analgesics. 3. The questionnaire survey showed that the embolization before radical nephrectomy was performed in 62% of the hospitals as a whole, including 81 hospitals (41%) in which the embolization was performed case by case. In the whole of hospitals, 21% performed the embolization principally by evaluating the significance of the embolization. On the other hand, 19% of the hospitals did not perform by the reason of no significance of the embolization on the treatment of renal cell carcinoma. As shown in this questionnaire survey, the significance of the embolization before radical nephrectomy was still debatable in our country. 4. In 62% of the hospitals where the embolization is carried out, as a whole, the period from embolization to the nephrectomy was 3-7 days. And in 42% of the hospitals as a whole absolute ethanol was principally used as an embolizing agent. In conclusion we believe that absolute ethanol was useful and should find further application as an embolizing agent before the radical nephrectomy.

Aged↗
PubMed1993

Urinary laminin P1 as an index of glycemic control in children with insulin-dependent diabetes mellitus.

OBJECTIVE: To evaluate the clinical meanings of urinary laminin P1, urinary laminin P1 concentrations in children with insulin-dependent diabetes mellitus (IDDM) were measured and compared with urinary levels of albumin, kappa light chain (kappa-LC), alpha 1-microglobulin (alpha 1-MG), beta 2-microglobulin (beta 2-MG), and n-acetyl-b-D-glucosaminidase (NAG). RESEARCH DESIGN AND METHODS: Forty-six children with IDDM and 31 age-matched controls were studied. The first urine in the morning was collected for three days and stored at -20 degrees C until assayed. The mean values were used for the study. Radioimmunoassay (RIA) was used to measure of laminin P1, kappa-LC, alpha 1-MG, and beta 2-MG. NAG and haemoglobin Aic (HbA1c) concentrations were measured by a colorimetric method and high-performance liquid chromatography, respectively. RESULTS: Urinary laminin P1 levels in IDDM were 54.2 + 3.4 (SE) mU/microM.Cr, significantly higher than those in control subjects (40.7 +/- 2.3 mU/microM.Cr, p < 0.01). In 10 out of 46 patients (21.7 percent), the values were higher than the mean +/- 2 SD of controls. Urinary albumin, kappa-LC, alpha 1-MG, beta 2-MG, and NAG in IDDM were higher than those in control subjects (p < 0.01). There were significant correlations between urinary laminin P1 levels and urinary albumin, kappa-LC, NAG, alpha 1-MG, and beta 2-MG. A significant correlation was also shown between urinary laminin P1 and HbA1c concentrations (p < 0.01). CONCLUSIONS: From the above results, we conclude that urinary laminin P1 concentrations could be one of the clinical indexes for glycemic control and damage of the glomerulus in IDDM.

Acetylglucosaminidase↗
PubMed1992

Mutagenic specificities of four stereoisomeric benzo[c]phenanthrene dihydrodiol epoxides.

The pS189 shuttle vector carrying a supF target gene was used to compare the mutagenic specificities of the four configurational isomers of benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxide. One of these isomers is the most tumorigenic dihydrodiol epoxide tested to date and another is essentially inactive as a tumorigen. Overall mutagenicities were not correlated with tumorigenicities, but each configurational isomer induced a unique spectrum of mutational hot spots in the supF target gene, which monitors primarily point mutations. It is suggested that the demonstrated isomer-specific selectivity for mutation targets within the supF gene may be indicative of a similar selectivity for one gene versus another and that such selectivity may be one determinant of relative tumorigenicity.

Base Sequence↗
PubMed1992

Analysis of the roles of CD4+ and CD8+ T cells in autoimmune diabetes of NOD mice using transfer to NOD athymic nude mice.

The NOD mouse, which spontaneously develops insulitis and overt diabetes, is a model of autoimmune type I diabetes mellitus. For the precise analysis of the roles of CD4+ and CD8+ T cells in the pathogenesis of this mouse, these subsets must be transferred into recipients that are completely free of T cells and pathological changes. We used athymic NOD nude mice, which congenitally lack mature T cells and are free of insulitis and hyperglycemia up to the age of 60 weeks, as recipients for this purpose. To the nude recipients we transferred either one of a highly purified CD4+ or CD8+ T cell subset derived from non-diabetic female NOD mice; any in vivo increase in the contaminating T cell subsets was prevented by injecting the antibody homologous to it. Most of the T cell-reconstituted recipients were treated with cyclophosphamide to promote the onset of overt diabetes. Transfer of the CD8+ T cell subset alone did not induce insulitis or hyperglycemia. In contrast, transfer of the CD4+ T cell subset alone produced insulitis, but not hyperglycemia, in all the recipients. However, the subsequent transfer of CD8+ T cells into CD4+ T cell-reconstituted recipients induced severe insulitis and hyperglycemia in almost all the recipients. In these diabetic recipients, we observed severe damage of the pancreatic islets and the infiltration of a large number of CD8+ T cells into the remaining islets; insulin-secreting beta cells were no longer detected. These results suggest that CD4+ T cells play a predominant role in the development of insulitis and that CD8+ T cells migrate into the islets and are subsequently, with the aid of CD4+ T cells, differentiated into killer cells which act against beta cells.

Animals↗