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Biomedical subjects

K Yasuda

Publications and source records attributed to K Yasuda.

At least 793 records · Page 44Linked to original sources
PubMed1992

Pseudo-adrenal incidentaloma: magnetic resonance imaging in a patient with para-adrenal Castleman's disease.

We report a case of para-adrenal angiofollicular lymph node hyperplasia (Castleman's disease) of the hyaline-vascular type. The mass could not be differentiated from an adrenal tumor by ultrasonography and computed axial tomography (CT). However, magnetic resonance imaging (MRI) suggested the possibility of an extra-adrenal origin of the mass. The intensity of the mass by MRI was homogeneous and of a higher intensity in the T2-weighted image than in the T1-weighted image, a finding similar to lymphadenopathy, lymphatic tumorous mass or metastatic tumor of the lymph node. Ultrasonography, CT and MRI may not be useful in characterizing Castleman's disease, but MRI was useful to distinguish asymptomatic para-adrenal masses from those of adrenal origin.

Adrenal Gland Neoplasms↗
PubMed1992

Monoclonal antibody to a common antigen of secretory granule membranes: intracellular localization and recycling of the antigen after secretion.

Monoclonal antibody (MAb) 170-5 was generated to the secretory granule membrane of rat parotid acinar cells. The MAb recognized integral membrane glycoproteins (SG 170 antigen) localized on the luminal side of the secretory granules with N-linked carbohydrates, molecular weights 92, 84, 76, 69, and 65 KD. Immunohistochemical studies indicated that the SG 170 antigen was found in the secretory granules of both exocrine and endocrine cells and in the lysosomes of various cells in the rat. Immunoelectron microscopy with immunogold revealed that the antigen was present on the membrane of the secretory granules, lysosomes, the Golgi vesicles, and condensing vacuoles in pancreatic and parotid acinar cells and in AR42J rat pancreatic tumor cells; the Golgi stacks exhibited no immunoreaction. The common localization of the antigen in the secretory granule membranes indicated that this antigen may play an essential role in regulated secretion. Employing HRP-labeled MAb 170-5, we followed the retrieval of the antigen after exocytosis in AR42J cells. The MAb was internalized specifically with antigen-mediated endocytosis. It was transported to endosomes, subsequently to the trans-Golgi network, and then packaged into secretory granules. However, the Golgi stacks revealed no uptake of the labeled antibody.

Animals↗
PubMed1992

The hormonal regulation of platelet-activating factor-acetylhydrolase in the rat.

Platelet-activating factor-acetylhydrolase (PAF-AH), the enzyme that inactivates PAF, is decreased in the plasma of both rabbits and humans during the latter stages of pregnancy. The activity of the enzyme was decreased in rats by the administration of 1,3,5(10)-estratrien-17 alpha-ethynyl-3,17 beta-diol (17 alpha-ethynylestradiol) and increased by dexamethasone treatment. In the present study, we have further defined the hormonal regulation of PAF-AH levels in plasma of adult and juvenile rats. Estrone (E1), 17 beta-estradiol (E2), estriol (E3), and various progestins [4-pregnen-6 alpha-methyl-17 alpha-ol-3,20-dione (medroxyprogesterone), 4-estren-17 alpha-ethynyl-17 beta-ol-3-one (norethindrone), and 5(10)-estren-17 alpha-ethynyl-17 beta-ol-3-one (norethynodrel)] were administered to adult rats, and the plasma PAF-AH activities were assayed. E1, E2, and E3 administration to adult female rats lowered the plasma PAF-AH activity, E3 being the most effective. After administration of these estrogens the activity returned to the preinjection level within 4 days. The administration of medroxyprogesterone resulted in a 2-fold increase in plasma PAF-AH activity in adult female rats, and the activity remained elevated for up to 30 days. When adult male rats were treated with similar doses only a 20% increase was observed and the PAF-AH activity returned to control values by day 10. In contrast, norethindrone and norethynodrel administration resulted in a reduction of the enzyme activity in adult female rats. The plasma PAF-AH activity in juvenile male and female rats (3 weeks of age, 45-60 g body wt) was two times higher than that in adult rats of both sexes and spontaneously decreased up to the time of puberty. When juvenile male or female rats were injected with either 17 alpha-ethynylestradiol or medroxyprogesterone, a minimal change in PAF-AH activity was observed. In contrast, when dexamethasone was administered to juvenile male and female rats the plasma PAF-AH activity increased in a manner similar to adult animals. It is suggested that estrogens cause a decrease and medroxyprogesterone an increase in plasma PAF-AH activity. It is suggested that the different responsiveness to medroxyprogesterone between adult female and male rats and juvenile animals may depend on the concentration of the hormone receptor in the tissue responsible for the synthesis of PAF-AH. The decrease in PAF-AH activity after the administration of norethindrone and norethynodrel may be due to the known estrogenic activity of these steroids.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1992

Differential expression of aminopeptidase-N on human ovarian granulosa and theca cells.

The expression of aminopeptidase-N and neutral endopeptidase in human ovarian tissue was examined using specific monoclonal antibodies for each of these peptidases and histochemical staining for enzyme activity. Aminopeptidase-N is a membrane-bound metalloprotease catalyzing the removal of N-terminal amino acids from peptides and was detected by immunofluorescence staining on theca interna cells in secondary follicles and on luteinized thecal cells in preovulatory follicles and corpora lutea. However, aminopeptidase-N was not detected on granulosa cells. Peptidase activity was also detected by histochemical staining on theca interna cells and luteinized thecal cells. Luteinized granulosa cells showed peptidase activity, despite the lack of aminopeptidase-N. Neutral endopeptidase was not detected in ovarian granulosa and thecal cells. These observations indicate that aminopeptidase-N can be a useful surface marker for thecal cells.

Adult↗
PubMed1992

Cytokine modulation of progesterone and estradiol secretion in cultures of luteinized human granulosa cells.

To clarify the possible roles of cytokines in the regulation of luteal cell function, we examined the effects of interferon (IFN), interleukin-1 (IL-1), and tumor necrosis factor (TNF) on progesterone and estradiol secretion in cultures of luteinized human granulosa cells. IFN gamma reduced hCG-stimulated progesterone secretion in a concentration-dependent manner; at its maximal inhibitory concentration (10 ng/mL), IFN gamma reduced progesterone secretion to 20% of that in the hCG-stimulated controls. Whereas other IFN (alpha and beta) reproduced the inhibitory effect of IFN gamma, IL-1 and TNF had no effect on hCG-stimulated progesterone secretion at concentrations of 1 and 10 ng/mL. IFN gamma also markedly reduced FSH-stimulated estradiol secretion. Unlike their effects on hCG-stimulated progesterone secretion, IL-1 and TNF reproduced the inhibitory effect of IFN gamma on FSH-stimulated estradiol secretion. IFN gamma significantly reduced both hCG- and FSH-stimulated cAMP generation in granulosa cells. IL-1 and TNF inhibited FSH-stimulated cAMP generation, but they did not inhibit hCG-stimulated cAMP generation. None of these cytokines reduced forskolin-stimulated cAMP generation, thus suggesting that these cytokines affect steps proximal to cAMP generation without affecting cAMP generation itself. IFN gamma also reduced progesterone secretion in response to (Bu)2cAMP, suggesting that it also affects steps distal to cAMP generation. This study has demonstrated that cytokines modulate the steroidogenesis of luteinized human granulosa cells in vitro; the results suggest that cytokines may play permissive roles in regulating luteal cell function.

Adult↗
PubMed1992

Long term follow-up of Cushing's disease treated with reserpine and pituitary irradiation.

Twenty adult patients with Cushing's disease treated with long term reserpine administration in combination with a single course of external pituitary irradiation were followed. Eleven patients experienced long term remissions of 15.5 +/- 8.9 (mean +/- SD) yr (55%) after a mean irradiation dose of 53.9 +/- 11.4 Gy and a mean duration of reserpine administration of 24.3 +/- 9.3 months. The long term remission rates of the patients irradiated with 50 Gy or less (n = 9; 45.0 +/- 7.1 Gy) and those with more than 50 Gy (n = 10; 61.3 +/- 3.3 Gy; excluding 1 irradiated with 66 Gy who developed brain necrosis) were 56% (5 of 9) and 60% (6 of 10), respectively, and did not differ significantly. There were no significant differences between the 2 groups with regard to the duration of reserpine administration or pretreatment clinical features. At the latest examination, regardless of the irradiation dose, all 9 patients with long term remission showed a higher level of plasma cortisol or 11-hydroxycorticosteroids in the morning than in the evening, normal suppressibility of plasma cortisol with overnight 1 mg dexamethasone (9 of 10), and well preserved responses of other pituitary hormones to various loading tests: normal responses of plasma ACTH to CRH (6 of 9), TSH (7 of 8), and PRL (5 of 8) to TRH and age-related normal responses of GH to GRH (4 of 8), LH (6 of 8), and FSH (6 of 8) to GnRH. These findings suggest that long term reserpine administration in combination with a conventional dose of pituitary irradiation is useful in the treatment of Cushing's disease.

Adolescent↗
PubMed1992

Human luteal cells express dipeptidyl peptidase IV on the cell surface.

We previously reported that human theca interna cells and small luteal cells express membrane-bound aminopeptidase N, and suggested that membrane-bound peptidases are involved in folliculogenesis and luteal function by regulating extracellular peptide concentrations. In this study, we examined the expression of dipeptidyl peptidase IV (DPP IV), which is a membrane-bound peptidase and has its catalytic domain at extracellular sites, in human granulosa cells, thecal cells of growing, preovulatory, and atretic follicles, as well as corpora lutea. Indirect immunofluorescence staining of ovarian tissues with specific monoclonal antibodies revealed that DPP IV was present in large and small luteal cells in corpora lutea. DPP IV peptidase activity was also detected histochemically in corpora lutea. In growing, preovulatory, and atretic follicles, there was weak immunoreactivity and DPP IV peptidase activity on luteinized theca interna cells, but not on granulosa cells. The expression of DPP IV on the cell surface of large and small luteal cells was confirmed by indirect immunofluorescence staining of freshly isolated luteal cells. These results indicate that DPP IV is a useful surface differentiation marker of human luteal cells and suggest that peptidases are involved in luteal function.

Adult↗
PubMed1992

Cardiopulmonary function in dogs with serious chronic heartworm disease.

Cardiopulmonary function was examined in 18 dogs with serious chronic heartworm disease showing ascites, subcutaneous edema, prostration, weakness, jaundice and so on. After surgical heartworm removal from the pulmonary arteries, 10 dogs recovered (surviving group), and 8 dogs died or were euthanatized because of poor prognosis (nonsurviving group). The number of live heartworms residing in the pulmonary arteries of the surviving group tended to be larger than that in the nonsurviving group. At necropsy, severe pulmonary arterial lesions such as thromboembolism including dead heartworms, proliferative and villous lesions and intimal hyperplasia were noticed in all dogs examined, and tended to be severer in the nonsurviving group. Heartworm-coiling around the tricuspid valve chord was found in 1 dog of the surviving group and 4 dogs of the nonsurviving group. Before heartworm removal, there was no significant difference in the mean pulmonary arterial pressure (MPAP) between the surviving and nonsurviving group. Right atrial pressure (v-wave) was higher, and the cardiac index (CI) was lower in the nonsurviving group. Arterial oxygen tension was lower in the surviving group than in the heartworm-free group, and it was lower in the nonsurviving group than in the surviving group. Carbon dioxide tension was lower in the surviving group than in the heartworm-free group. Bicarbonate concentration (HCO3-) was lower both in the surviving and nonsurviving groups than in the heartworm-free group. One week after heartworm removal, MPAP decreased (P less than 0.05), and CI and HCO3- tended to increase in the surviving group.

Animals↗
PubMed1992

Characterization of insulin receptors in the bovine adrenal cortex and medulla.

In order to identify insulin receptors in the bovine adrenal cortex and medulla, we have studied 125I-porcine insulin binding to the membrane preparations from the bovine adrenal cortex and medulla. 125I-porcine insulin bound not only to the bovine adrenal cortex but to the medulla in time-, temperature-, and pH-dependent manners. The maximum levels of 125I-porcine insulin binding in the two tissues were observed at 4 degrees C for 24 h of incubation, and its optimum pH ranged from 7.6 to 8.0. Under these conditions, at tracer concentration of porcine insulin (200 pg/ml), 10.4% and 6.6% of 125I-porcine insulin added to each reaction tube bound specifically to 10(5) x g-pellet fractions (microsomal membrane) from the cortical tissue (0.3 mg of protein) and from the medullary tissue (2 mg of protein), respectively. 125I-porcine insulin binding was observed predominantly in the microsomal membrane from the bovine adrenal cortex, and in a 15,000 x g- pellet fraction (synaptosomal membrane) from the bovine adrenal medulla. Scatchard analysis of binding data yielded curvilinear plots in each tissue. Analysis of curvilinear plots based on two sites model revealed similar affinity constant between the cortex and medulla. Receptor concentration of the cortex was several times higher than that of the medulla. In the two bovine adrenal tissues, human proinsulin and insulin-like growth factor I (IGF-I) had about 1/100 potency compared to porcine insulin in displacing 125I-porcine insulin binding. Porcine glucagon added with concentration up to 10(-6) M did not inhibit 125I-porcine insulin binding to both the cortex and the medulla.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex↗
PubMed1992

Synergistic actions of cytokines and growth factors in enhancing porcine granulosa cell growth.

In our studies of the growth-promoting effect of a cytokine, interleukin-1 (IL-1), on cultured porcine granulosa cells, we found that the potency of IL-1 action correlated with the serum concentration in the culture medium and that IL-1 acted synergistically with insulin to increase the number of cells in the presence of low serum concentrations (0.1-1%). With granulosa cells maintained in a quiescent state under serum-free conditions, we therefore examined the effects of combined treatment with IL-1 and peptide growth factors, including insulin, on [3H]thymidine incorporation by these cells. IL-1 by itself enhanced [3H]thymidine incorporation in a concentration-dependent manner. Moreover, IL-1 acted synergistically with insulin, epidermal growth factor (EGF), or fibroblast growth factor (FGF) to enhance [3H]thymidine incorporation. Combinations of maximally effective concentrations of insulin (1 micrograms/ml), EGF (1 ng/ml), or FGF (50 ng/ml) with the maximally effective concentration of IL-1 (10 ng/ml) increased the levels of [3H]thymidine incorporation to 10-, 22-, and 20-fold, respectively, over the control values. Whereas IL-2 (0.1-100 ng/ml) did not affect [3H]thymidine incorporation, tumor necrosis factor alpha (TNF alpha) stimulated [3H]thymidine incorporation by itself and reproduced the actions of IL-1 to act synergistically with insulin, EGF, or FGF. When IL-1 and TNF alpha were added together in relatively low concentrations (1 ng/ml each), the combination had synergistic effects in enhancing [3H]thymidine incorporation. The present study demonstrates that cytokines and peptide growth factors act synergistically to markedly enhance porcine granulosa cell growth in vitro.

Analysis of Variance↗
PubMed1992

Beneficial effects of high daily dose bromocriptine treatment in Cushing's disease.

Treatment with a high daily dose bromocriptine was evaluated in 6 Cushing's disease patients (4 females and 2 males; aged 23 to 56 years). The highest doses administered were 40 mg to patient 1, 55 mg to patient 2, 35 mg to patient 3, 25 mg to patient 4, 25 mg to patient 5, and 17.5 mg to patient 6. The former 3 cases, 2 (patients 1 and 2) of whom were previously reported and further followed up, showed clinical and biochemical improvement with the regimen. Patient 1 who obtained remission with 40 mg/day has been on remission for further 14 months with a total of 36 months. Patient 2, who had a reduction in pituitary tumor size with 35 mg daily, relapsed thereafter. The therapy, however, resolved the paradoxical responses of plasma ACTH and cortisol to arginine. Readministration of bromocriptine resulted into another clinical and biochemical improvement with 45 to 55 mg/day. Patient 3, a relapsed case after a remission with reserpine plus pituitary irradiation, showed an improvement in the 24-h urinary free cortisol excretion with 35 mg/day. Patient 4 was the only case who had a marked decrease in plasma cortisol (basal; 16.3, nadir; 1.9 micrograms/dl) after a single-dose bromocriptine test among the 5 cases tested. The patient had favorable response with 25 mg/day for 2 months but the dose was not increased after an escape. Patient 5 received the drug in 4 occasions, 7.5 to 25 mg/day, in combination with several agents, which failed to induce clinical remission. The last patient did not respond to a maximum dose of 17.5 mg/day. These observations suggest that, regardless of the result of a single-dose bromocriptine test, treatment with a high daily dose of bromocriptine, 35 mg or more, may be necessary to obtain a favorable clinical response and normal cortisol secretion.

Adrenocorticotropic Hormone↗
PubMed1992

Resolution of possible paradoxical responses of gonadotropins to thyrotropin-releasing hormone with bromocriptine therapy in a patient with follicle-stimulating hormone-secreting pituitary adenoma.

We report the effectiveness of bromocriptine therapy in resolving the abnormal responses of plasma FSH and LH to TRH in a 70-year-old male with FSH-secreting pituitary macroadenoma who had unsuccessful transsphenoidal pituitary surgery. In the pre-treatment and post-operative periods, respectively, basal plasma levels of FSH were increased to 88.7 and 65.6 mIU/ml (normal range; 8.5-32.4) but those of plasma LH were normal being 7.0 and 4.1 mIU/ml; (normal range; 4.1 to 14.0). The responses of plasma FSH and LH to LHRH were exaggerated and their paradoxical responses to TRH were highly suggested. During the bromocriptine therapy, the basal level of plasma FSH was normalized and that of plasma LH remained normal. The magnitude of FSH and LH responses to LHRH decreased and their paradoxical responses to TRH were completely resolved.

Adenoma↗
PubMed1992

Secretory regulation of 19-hydroxyandrostenedione in normal man.

To evaluate the secretory regulation of 19-hydroxyandrostenedione (19-OH-AD), its plasma concentration was measured before and after stimulation and inhibition tests for the ACTH-adrenal axis and the renin-angiotensin system in 50 normal subjects. Basal levels of plasma 19-OH-AD did not correlate with either those of plasma renin activity (PRA) or the plasma aldosterone concentration (PAC), but positively correlated with those of plasma cortisol. Plasma 19-OH-AD was stimulated by 0.25 mg ACTH-(1-24) and was suppressed by 1 mg dexamethasone (DEX) as were plasma cortisol and PAC. On the other hand, with 2-h standing alone or iv 40 mg furosemide plus 2-h standing, plasma 19-OH-AD and cortisol did not increase but PRA and PAC did. With iv furosemide plus 2-h standing with 3 mg DEX pretreatment, plasma 19-OH-AD and cortisol did not respond either, but PRA and PAC increased. With 25 mg oral captopril following 1-h standing with 3 mg DEX pretreatment, plasma 19-OH-AD and cortisol did not change but PAC decreased. These results indicate that the secretion of 19-OH-AD is mainly under the control of the ACTH-adrenal axis rather than the renin-angiotensin system.

Adolescent↗
PubMed1992

Ultrasonography in the diagnosis of aldosterone-producing adenoma: is it useful?

The usefulness of ultrasonography (US) in the diagnosis of aldosterone-producing adenoma(s) (APA) was compared with computed tomography (CT) and adrenal scintigraphy in 13 patients. The initial examination with US could demonstrate four of seven right APA. Repeat examinations later in two patients whose tumors were initially not detectable did reveal a tumor in one patient. On the other hand, two left APA were delineated on the initial trial. The other seven left APA, except two small APA in one patient, could be delineated during repeat US examinations performed on other days. With CT, all APA were detected during the first or second trial except for the smallest one. The rate of localization by adrenal scintigraphy with dexamethasone pretreatment was 11 of 13 patients. CT had the highest localization rate. However, US was shown to be useful in the localization diagnosis of APA on repeat examinations with a high delineation rate comparable to CT.

Adenoma↗
PubMed1992

Expression of GLUT1 and GLUT2 glucose transporter isoforms in rat islets of Langerhans and their regulation by glucose.

Previous studies revealed that rat islets express the GLUT2-liver facilitative glucose transporter isoform, a glucose carrier with a low affinity for glucose but a high capacity for glucose transport. These studies indicated the presence of a second glucose transporter in rat islets; however, they did not indicate to which of the five known facilitative glucose transporters it corresponded. In this study, we isolated RNA from rat islets of Langerhans and confirmed the presence of GLUT2 mRNA. In addition, we present data indicating that the second isoform expressed in islets is the GLUT1-erythrocyte isoform. The effect of culturing islets in 5.5, 8.3, or 11.1 mM glucose on the levels of GLUT1 and GLUT2 mRNA also was examined. The levels of GLUT1 and GLUT2 mRNA were two- and threefold higher, respectively, in islets cultured for 24 h in 11.1 mM glucose compared with those incubated in the presence of 5.5 mM glucose. Therefore, the previously observed increase in GLUT2 mRNA levels in the islets of rats made hyperglycemic by chronic infusion of glucose can be mimicked in vitro, implying that glucose regulates GLUT2 mRNA expression.

Animals↗
PubMed1992

Human GLUT4/muscle-fat glucose-transporter gene. Characterization and genetic variation.

Four overlapping DNA fragments spanning 32 kb containing the human GLUT4 facilitative glucose-transporter gene were isolated and characterized. The sequence of the GLUT4 gene (approximately 6.3 kb) and 2.0 kb of the promoter region was determined. The sequence of the promoter revealed potential binding sites for transcription factors known to regulate gene expression in muscle cells and adipocytes. However, transfection of constructs including 2 kb of the GLUT4 promoter fused to the bacterial CAT gene into 3T3-L1 adipocytes displayed only weak promoter activity. Because insulin resistance plays a prominent role in the development of NIDDM, genetic variation in the sequence of GLUT4 also was evaluated. Oligonucleotide primer pairs were selected that allowed the protein-coding region of the human GLUT4 gene to be amplified by PCR. The sequence of the protein-coding region of the GLUT4 gene and all intron-exon junctions was determined for a single diabetic Pima Indian and was identical to that of the cloned gene and cDNA. SSCP analysis was used to screen patients with diabetes mellitus and normal, healthy nondiabetic individuals for mutations at the GLUT4 locus. In addition to the silent substitution in the codon for Asn130 (AAC or AAT) and a Val383 (GTC)-->Ile(ATC) replacement described previously, two new variants were identified. One was a T-->A substitution in intron 1 that was found in 1 of 36 NIDDM patients who were typed for this variant. The second was a Ile385(ATT)-->Thr(ACT) replacement that occurred in 1 normal individual and was not found in any of 676 other normal and diabetic subjects. A large and racially diverse group of normal and diabetic individuals also was screened for the Ile383 polymorphism. It occurred in both diabetic and nondiabetic subjects. There is no indication from our data that these polymorphisms are associated with NIDDM.

3T3 Cells↗
PubMed1992

Glucose as regulator of glucose transport activity and glucose-transporter mRNA in hamster beta-cell line.

To investigate the role of glucose in regulating glucose transporters in pancreatic beta-cells, we studied the hamster clonal beta-cell line HIT-T15, which retains responsiveness to glucose. Northern blot analysis demonstrates that GLUT2 and GLUT1 mRNA are abundant in HIT cells. After a 24-h culture with various concentrations of glucose (0-22.2 mM [0-400 mg/dl]), the GLUT2 mRNA level in HIT cells increased by 40% at 22.2 mM (400 mg/dl) glucose compared with 11.1 mM (200 mg/dl) without a change in mRNA stability. It also decreased proportionally to the reduction of glucose concentration. Glucose deprivation resulted in a decrease of GLUT2 mRNA to an almost undetectable level, with a marked increase in the degradation rate of mRNA. In contrast, the GLUT1 mRNA was not affected by glucose. We show that glucose uptake is highest in HIT cells incubated at 2.8-5.5 mM (50-99 mg/dl) glucose for 24 h, and that levels in cells cultured at 0 mM (0 mg/dl) and 22.2 mM (400 mg/dl) glucose decrease to approximately 20% of the maximum level. This decrease is consistent with the effects of glucose on glucose-stimulated insulin secretion in HIT cells. Our results indicate that glucose is involved in regulating GLUT2 mRNA and glucose uptake activity and that the glucose responsiveness of the insulin secretion correlates with the glucose-induced change in glucose uptake activity in HIT cells.

Animals↗