In situ hybridization for the analysis of fos oncogene in melanoma cells.
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Animals↗
Biomedical subjects
K Urabe
Publications and source records attributed to K Urabe.
Functional properties of cloned melanogenic proteins.
Several genes critical to the regulation of melanin production in mammals have recently been cloned and characterized. They map to the albino, brown, and slaty loci in mice, and encode proteins with similar structures and features, but with distinct catalytic capacities. The albino locus encodes tyrosinase, an enzyme with three distinct catalytic activities--tyrosine hydroxylase, 3,4-dihydroxyphenylalanine (DOPA) oxidase and DHI (5,6-dihydroxyindole) oxidase. The brown locus encodes TRP-1 (tyrosinase-related protein-1), which has the same, but greatly reduced, catalytic potential. The slaty locus encodes TRP-2, another tyrosinase related-protein, which has DOPAchrome tautomerase activity. In this study we have examined the enzymatic interactions of these proteins, and their regulation by a novel melanogenic inhibitor. We observed that tyrosinase activity is more stable in the presence of TRP-1 and/or TRP-2, but that the catalytic function of TRP-2 is not affected by the presence of TRP-1 or tyrosinase. Other factors also may influence melanogenesis and a unique melanogenic inhibitor suppresses tyrosinase and DOPAchrome tautomerase activities, but does not affect the spontaneous rate of DOPAchrome decarboxylation to DHI. The results demonstrate the catalytic functions of these proteins and how they stably interact within a melanogenic complex in the melanosome to regulate the quantity and quality of melanin synthesized by the melanocyte.
Animals↗
Effect of anoxic preperfusion on ischemic myocardial injury in isolated rat hearts.
Anoxic perfusion prior to sustained ischemia (anoxic preperfusion), reportedly improves postischemic functional recovery of the heart, but its mechanism has not been well understood. The present study aimed to characterize the cardioprotective effects of anoxic preperfusion and its relationship to extracellular Ca++ levels. Following 10 min of aerobic perfusion, isolated rat hearts were assigned to a 10 min aerobic perfusion or to a 10 min anoxic perfusion. The hearts were then subjected to 30 min of global ischemia and 30 min of aerobic reperfusion. When the perfusate-free Ca++ concentration was 2.0 mM, postischemic recovery of left ventricular developed pressure was significantly improved by anoxic preperfusion (91.9 +/- 2.9% of baseline value vs. 50.5 +/- 12.9% after 30 min reperfusion in the controls). However, the improvement of postischemic ventricular function by anoxic preperfusion was abolished when perfusate Ca++ was reduced to 1.0 mM and the contractile function was rather suppressed during early reperfusion by anoxic preperfusion when the Ca++ level was 0.7 mM (87.5 +/- 11.8% vs. 115.6 +/- 13.9% after 10 min of reperfusion). On the other hand, lactate accumulation during the global ischemia was significantly less in anoxic preperfused hearts compared with untreated hearts both when perfusate Ca++ was 0.7 mM (61.3 +/- 5.1 vs. 85.9 +/- 6.8 mumol/g dry) and when it was 2.0 mM (43.8 +/- 2.0 vs. 140.3 +/- 14.1 mumol/g dry). The amount of myoglobin released after global ischemia was not different between untreated and anoxic preperfused hearts regardless of the perfusate Ca++ level. The results suggest that anoxic preperfusion does not reduce ischemic myocardial necrosis, but it attenuates myocardial stunning. That effect of anoxic preperfusion on the stunning is dependent on the extracellular Ca++ level and is not totally explained by suppression of ischemia-induced lactate accumulation.
Adenosine Triphosphate↗
[The effects of 20% saline solution on the circulatory dynamics during the hemorrhagic shock state].
This experiment was performed to study the effects of administration of 20% saline solution 1.5 ml.kg-1 on the circulatory dynamics during the hemorrhagic shock state. Administration of 20% saline solution 1.5 ml.kg-1 during the hemorrhagic shock produced twofold increase of the mean arterial blood pressure for one hour, 2.5 fold increase of the cardiac output, increasing tendency in the mean pulmonary arterial pressure, central venous pressure, and the heart rate, accompanied by decrease in total peripheral resistance and the pulmonary blood vessel resistance. There were no improvements in acidosis and hematocrit. These data suggest that the circulatory improvements after the administration of 20% saline solution depend on an increase in cardiac output as the result of improvements in both pre- and after-load, but not of plasma volume expansion. The results also suggest that the administration of 20% saline solution 1.5 ml.kg-1 is useful for an emergency case with acute circulatory insufficiency or for emergency resuscitation.
Animals↗
p53 gene mutations in colorectal tumors from patients with familial polyposis coli.
The p53 gene has been elucidated as a tumor suppressor gene, and inactivation of this gene caused by deletion or point mutations may play a crucial role in the development of human malignancies. In colorectal carcinomas with an allelic deletion of the p53 gene, the remaining p53 gene was mutated with considerable frequency. It is most difficult to detect point mutations or small deletions of the gene because the mutations occur in diverse regions, although four hot spots have been observed [J.M. Nigro et al., Nature (Lond.), 342: 705-708, 1989]. The polymerase chain reaction and denaturing gradient gel electrophoresis facilitate detection of mutations in the hot spots of the p53 gene. Using these methods, we detected mutations in three adenomatous polyps and one carcinoma from familial polyposis coli patients and three carcinomas of sporadic cases. The DNA sequence analysis confirmed mutations of the p53 gene in 2 adenomas (13 base-pair deletions in one and a point mutation in the other) and 1 carcinoma (point mutation) from familial polyposis coli patients. These results suggest that the p53 gene mutations may be involved in the formation not only of carcinomas but also of adenomas which occur in familial polyposis coli patients.
Adenomatous Polyposis Coli↗
Correlation between HLA-A2-Bw46-DRw8 haplotype and increased levels of complement components (C4 and C4a) in patients with psoriatic arthritis.
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Arthritis, Psoriatic↗
Onset of subacute aggravation of chronic thyroiditis followed immediately by transient hypothyroidism during antithyroid drug therapy for Graves' hyperthyroidism.
A 56-year-old man presented with clinical and biochemical hyperthyroidism with high thyroid 99mTc uptake, positive result for antimicrosomal antibody (MCHA; 1:8,100) and markedly high activities of thyrotropin-binding inhibitory immunoglobulin (TBII; 90.0%) and thyroid-stimulating antibody (TSAb; 2,400%). Fifty days after the initiation of antithyroid drug therapy, he developed a painful tender enlarged thyroid and an accelerated erythrocyte sedimentation rate (ESR), which were followed immediately by hypothyroidism with a transient increase in MCHA titer (peak; 1:218,700) despite of maintenance of high TBII and TSAb activities. Two and a half months after the recovery from hypothyroidism, recurrent hyperfunction was observed with further elevation of TSAb activity (4,643%). After about 2 weeks, recurrences of a painful tender enlarged thyroid and an accelerated ESR, which were followed by abrupt progression to hypothyroidism, were found. Specimens obtained when he had still slightly tender goiter after the first and second episodes of neck pain showed microscopically extremely extended interstitial fibrosis with collapsed follicles and moderate lymphocytic infiltration. Thyroid-stimulation-blocking antibody was not detected at either onset of hypothyroidism. Thus, it is possible that Graves' disease, subacute aggravation of chronic thyroiditis and hypothyroidism coexist in the same individual. In such patients, thyroid status may be determined by the degree of each of the stimulating factors (TSH, TSAb and/or unknown factors) and suppressive or destructive factors (humoral and/or cellular) and may be changed in a very short interval.
Autoantibodies↗
Does myocardial stunning contribute to infarct size limitation by ischemic preconditioning?
BACKGROUND: The mechanism through which ischemic preconditioning causes cardioprotection is unknown. The present study investigated the role of stunning in preconditioning. METHODS AND RESULTS: We studied three different protocols of preconditioning: two cycles of 2-minute ischemia separated by 5-minute reperfusion (2'PC), one cycle of 5-minute ischemia by 5-minute reperfusion (5'PC1), and two cycles of 5-minute ischemia separated by 5-minute reperfusion (5'PC2). In the first series of experiments, the stunning associated with 2'PC, 5'PC1, or 5'PC2 was assessed using an epicardial Doppler transducer in anesthetized open-chest rabbits. The thickening fraction (percent baseline) of the preconditioned region was 76.8 +/- 7.2% (mean +/- SEM) after 2'PC but 31.4 +/- 9.2% and 34.3 +/- 9.7% after 5'PC1 and 5'PC2, respectively, which were significantly lower, thus indicating more severe stunning than that after 2'PC. In the second series of experiments, a branch of the left circumflex artery was occluded for 30 minutes and then reperfused for 72 hours in four groups of rabbits. One group was not preconditioned and three groups were preconditioned with 2'PC, 5'PC1, or 5'PC2 protocols before the 30-minute ischemia. In contrast to the differences observed in the stunning in the first series of experiments, histological infarct size was similar in the three preconditioned groups (21.1 +/- 3.0% of area at risk after 2'PC, 20.1 +/- 3.4% after 5'PC1, 16.4 +/- 4.2% after 5'PC2), all of which were significantly smaller than that in the unpreconditioned group (43.9 +/- 5.0%). The third series of experiments examined the degree of stunning by 2'PC, 5'PC1, or 5'PC2 and the size of infarct (tetrazolium staining) in the same animal after 30-minute ischemia/3-hour reperfusion; again, the results showed no significant correlation between degree of stunning and infarct size. CONCLUSIONS: The myocardial infarct size-limiting effect of preconditioning did not correlate with the degree of myocardial stunning accompanying preconditioning. Thus, it is unlikely that myocardial stunning contributes to the cardioprotective effect of ischemic preconditioning.
Animals↗
Perioperative management of a patient with congenital afibrinogenemia.
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Journal Article↗
Development of postpartum spontaneously resolving transient Graves' hyperthyroidism followed immediately by transient hypothyroidism.
A 25-year-old woman with a history of Graves' disease, in remission for 8.5 years following 6 months of methimazole therapy, first came to our attention 5 months after her first delivery with clinical and biochemical hypothyroidism, markedly elevated titre of anti-thyroid microsomal antibody (MCHA; 1:102400) and mildly elevated activity of thyrotropin-binding inhibitory immunoglobulins (TBII; 29.5%). After short-term (3 months) treatment with L-thyroxine therapy, the development of hyperthyroidism in the first trimester of the second pregnancy, which remitted through the second and third trimesters, was observed. TBII showed a peak value (93.1%) 1 month after the onset of hyperthyroidism, and a normal value (12.4%) 6 d after delivery. One month after the second delivery, the patient developed hyperthyroidism, with an elevation of 99mTc thyroid uptake (5.58%; normal range 0.5-2.5%), which was immediately followed by transient clinical and biochemical hypothyroidism. Concomitant increases in MCHA titre and TBII activity were observed after delivery, and both reached peak levels (1:409600 and 81.0%, respectively) one and a half months after the onset of hypothyroidism. Thyroid-stimulating antibody (TSAb), measured using FRTL-5 thyroid cells, was detected at a weakly positive level (161%) on initial examination, and the serial change in TSAb was almost identical to that in TBII. Patients with Graves' disease may develop Graves' type hyperthyroidism, followed immediately by transient hypothyroidism due to coexisting destructive autoimmune thyroiditis during the early postpartum period, despite increasing TSAb activity.
Adult↗
The mechanism involved in the conversion of thyrotropin receptor-bound blocking-type immunoglobulin G (IgG) to the stimulating-type by anti-human IgG antibodies.
It has been reported that the addition of antibody (Ab) against human immunoglobulin G (IgG) converts TSH receptor-bound blocking-type IgG to stimulating-type IgG. However, the detail of converting mechanism remains unclear. In this study we examined the mechanism involved in this conversion using FRTL-5 cells. Blocking-type IgG was obtained from a patient with hypothyroidism. FRTL-5 cells were first incubated with IgG solution, then washed with PBS and exposed to antihuman IgG Ab. The effect of antihuman IgG Ab on converting activity was dose dependent. Maximal stimulation of cAMP was achieved with an antiserum dilution of 1:75. It seems likely that antimicrosomal Ab does not interfere with cAMP production, since IgG with a high anti-hemagglutination antibody titer did not show converting activity. Of the several kinds of antibodies tested, Ab against human IgG-Fab fragment was the most effective in converting ability, while the least effective were those against human IgG-Fc fragment. Although the divalent F(ab')2 fragment of antihuman IgG was significantly more effective in its converting ability than the monovalent Fab fragment, the Fab fragment itself also converted blocking IgG to the stimulating type in a dose-dependent manner. Accordingly, receptor cross-linking or aggregation does not play a major role in promoting this converting phenomenon. When cells were first exposed to blocking-type IgG and then to both antihuman IgG Ab and bovine TSH, cAMP production was much greater than the sum of each alone. However, anti-IgG Ab alone did not affect the binding of blocking-type IgG to receptor. These results suggest that the addition of antihuman IgG Ab not only converts blocking-type IgG to the stimulating type but also recovers TSH activity via a postreceptor step. Forskolin, like TSH, showed an additive effect on cAMP stimulatory action with antihuman IgG. In contrast, cholera toxin and antihuman IgG Ab were not additive. The reason for this discrepancy remains unknown. In summary, our observation indicates that 1) the converting phenomenon is induced via IgG-TSH receptor complexes; 2) the mechanism aside from receptor aggregation, i.e. the recognition of a critical domain in TSH receptor molecule, seems necessary for promoting converting phenomenon; and 3) the addition of antihuman IgG Ab affects a postreceptor step via TSH receptor structures that differ from the TSH-binding site.
Adult↗
Chronic thyroiditis with painful tender thyroid enlargement and transient thyrotoxicosis.
Clinical and laboratory findings and long term outcome (1.5-9 yr) in 7 women and 1 man with chronic thyroiditis (CT) who had painful tender thyroid enlargement were evaluated and compared with those in 11 women with subacute thyroiditis (SAT). Histological features consistent with SAT were not demonstrable, and various forms of CT (fibrous variant, diffuse, or focal lymphocytic thyroiditis) were observed. There were no differences in mean age, duration of symptoms, erythrocyte sedimentation rate, and C-reactive protein values in the 2 diseases. Seven patients had a history of goiter, and none had a history of a preceding upper respiratory tract infection. The mean white blood cell count was significantly lower in CT than in SAT patients. Six CT patients had transient thyrotoxicosis with a marked depression of radioactive iodine uptake. Mean serum T4 and T3 levels and T3 to T4 ratio in these 6 patients did not differ from those in the SAT patients. Five (all with high antimicrosomal antibody titers) of 8 CT patients developed persistent hypothyroidism. In contrast, none of the SAT patients became permanently hypothyroid. TSH binding inhibitory immunoglobulins and thyroid stimulation-blocking antibody at recent examination were negative in these 5 patients. Patients with this disorder present with transient thyrotoxicosis, with a marked depression of the thyroid radioactive iodine uptake, and often develop goitrous or atropic persistent hypothyroidism. This disorder may represent acute exacerbation of an underlying immunological process during the course of CT. To differentiate this syndrome from SAT, thyroid biopsy is necessary.
Adult↗
Three patients who spontaneously developed persistent hypothyroidism during or following treatment with antithyroid drugs for Graves' hyperthyroidism.
Three patients with Graves' disease who spontaneously developed hypothyroidism after treatment with antithyroid drugs are described herein. Patient 1 developed a painful tender thyroid enlargement with a fever and accelerated erythrocyte sedimentation rate when she was receiving maintenance therapy with methimazole, and she progressed to persistent hypothyroidism with increased titers of antithyroglobulin and antimicrosomal antibodies and marked reduction of goiter size within the subsequent 2 months. Thyroid-stimulating hormone-binding inhibitory immunoglobulins (TBIIs) and thyroid stimulation-blocking antibody (TSBAb) were absent when she was hypothyroid. Hypothyroidism probably resulted from autoimmune thyroid destruction due to subacute aggravation of Hashimoto's thyroiditis. During the clinical course of patient 2, accelerated erythrocyte sedimentation rate and later transient increases of antimicrosomal and antithyroglobulin antibody titers were observed repeatedly (four times), and she finally fell into overt hypothyroidism. She also had negative results of tests for TBII and TSBAb. Her hypothyroidism appeared to result from repeated thyroid destruction due to aggravation of Hashimoto's thyroiditis. Patient 3 fell into hypothyroidism when receiving a small dosage of methimazole. The TBII and TSBAb were strongly active when she developed hypothyroidism, which thus seemed to be due to blocking antibody. Patients with Graves' hyperthyroidism may eventually progress to hypothyroidism later by several different mechanisms. Severe and sudden or slowly repeated thyroid destruction due to aggravation of Hashimoto's thyroiditis is one mechanism. Another may be the appearance of a blocking antibody to the TSH receptor.
Adult↗
Gene conversion in steroid 21-hydroxylase genes.
The steroid 21-hydroxylase gene, CYP21B, encodes cytochrome P450c21, which mediates 21-hydroxylation. The gene is located about 30 kb downstream from pseudogene CYP21A. The CYP21A gene is homologous to the CYP21B gene but contains some mutations, including a C----T change which leads a termination codon, TAG, in the eighth exon. We found the same change in a mutant CYP21B gene isolated from a patient with 21-hydroxylase deficiency. Furthermore, a reciprocal change--i.e., a T----C change in the eighth exon of the CYP21A gene--was observed in the Japanese population and was associated with the two HLA haplotypes, HLA-B44-DRw13 and HLA-Bw46-DRw8. These changes may be considered the result of gene conversion-like events.
Adrenal Hyperplasia, Congenital↗
Tissue-type plasminogen activator alone or in combination with thromboxane A2 synthetase inhibitor for ischemic myocardium.
Although the efficacy of tissue-type plasminogen activator (t-PA) for coronary thrombolysis is well established, its direct cardioprotective effect - independent of its thrombolytic effect - is still controversial. In addition, the potentiation of t-PA's direct cardioprotective effect by thromboxane A2 synthetase inhibitor has recently been reported. In this study, the authors examined whether t-PA alone or in combination with DP1904, a thromboxane A2 synthetase inhibitor, is able to salvage ischemic myocardium via a direct action on myocardium. In addition, the effect of these interventions on intramyocardial hemorrhage in reperfused infarcts was assessed. A branch of the coronary artery of the rabbit was occluded for 30 mins and then reperfused for 72 h. Myocardial infarct size and 'area at risk' were determined by histology and fluorescent particles, respectively. The extent of intramyocardial hemorrhage was graded using scores. Rabbits were divided into three groups: control, t-PA and DP1904 plus t-PA. The t-PA was administered intravenously at 500 iu/kg/min for 30 mins starting 5 mins prior to reperfusion. DP1904 was injected intravenously at a dosage of 10 mg/kg every 24 h starting 2 hr prior to coronary occlusion. Mortality was similar and hemodynamic parameters and area at risk were comparable between all three groups. The myocardial infarct size as a percentage of area at risk was 44.5 +/- 3.8% (mean +/- standard error) (n = 9) in the control group, 41.6 +/- 4.6% in the t-PA group (n = 8) and 51.3 +/- 5.2% in DP1904 plus t-PA group (n = 8), not significantly different (ANOVA). Neither were the hemorrhage scores significantly different between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Relationship between zinc and cellulose intakes in growing rats.
We have studied the effect of cellulose on the intestinal absorption of zinc and its metabolism with weanling male rats. Experimental diets were cellulose (5, 8 or 20%) and noncellulose containing normal zinc (AIN-76 mineral mix., 3.0 mg%) or high zinc (10 times of normal, 30 mg%). Weanling rats fed on these diets ad libitum for 16-42 days. There were no significant differences between noncellulose-feeding and cellulose-feeding groups in body weight gain or protein and DNA concentrations in the liver. The inhibitory effect of 20% cellulose on zinc absorption was observed in the long term experiment, as the concentrations of plasma zinc of the group receiving 20% cellulose were decreased significantly more than that of noncellulose-feeding group.
Animals↗
[Detection of activated oncogenes by Southern blot analysis].
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Animals↗
[Mutations in 21-hydroxylase gene caused by gene conversion-like events].
Two steroid 21-hydroxylase genes (CYP21A and CYP21B) alternate in tandem with two genes for the fourth component of complement (C4A and C4B) on the short arm of chromosome 6 between the loci of HLA-B and HLA-DR. The CYP21B gene encodes an adrenal microsomal cytochrome P-450, which is specific for steroid 21-hydroxylation (P450c21). A defect of this protein would cause 21-hydroxylase deficiency, which is an autosomal recessive disease and is the most common cause of congenital adrenal hyperplasia (CAH). On the other hand, the CYP21A gene, which is homologous to the CYP21B gene up to 98% in the nucleotide sequences, is a pseudogene due to several mutations in the coding region. One of the mutations is a C----T change leading a termination codon, TAG, in the 8th exon. 1) I cloned a CYP21B gene from a patient homozygous for HLA-Bw75-DRw9 by descent. I found a C----T change in the 8th exon of the CYP21B gene. This mutation would prevent a synthesis of 21-hydroxylase and was thought to be a crucial change to cause CAH in this patient. Because there was no apparent gross change in the organization of the C4-CYP21 region and this mutation is usually found in the CYP21A pseudogene, it seemed that a gene conversion-like event transferred the mutation from the CYP21A gene to the CYP21B gene. 2) A population study on the organization of C4-CYP21 region revealed that a reciprocal change, i.e. a T----C change in the 8th exon of the CYP21A gene, was observed in two HLA haplotypes, HLA-B44-DRw13 and HLA-Bw46-DRw8 haplotypes in Japanese population. The reciprocal changes also may be considered as a result of gene conversion-like events.
Gene Conversion↗