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Biomedical subjects

K Shizume

Publications and source records attributed to K Shizume.

At least 73 records · Page 4Linked to original sources
PubMed1991

Effects of retinoids on iodine metabolism, thyroid peroxidase gene expression, and deoxyribonucleic acid synthesis in porcine thyroid cells in culture.

Effects of retinoids on DNA synthesis, iodine metabolism, and thyroid peroxidase messenger RNA levels were studied in cultured porcine thyroid cells. Retinol (10(-8)-10(-5) M) alone did not affect DNA synthesis but potentiated that induced by epidermal growth factor or insulin-like growth factor-I without changes in the number or affinity of receptors for the growth factors, suggesting that retinol stimulates postreceptor events responsible for DNA synthesis. Retinol was an inhibitor of TSH-stimulated iodine metabolism. Iodide uptake and release of organified iodine stimulated by TSH or forskolin were inhibited dose dependently by treatment with retinol. The inhibition was detected at 10(-8) M and was approximately 50% at 10(-6) M. The potency of retinoic acid was comparable to that of retinol. The inhibitory effect of retinol was detected after treatments of thyroid cells for 24 h, and the maximal effect occurred after 48 h incubation. The cAMP accumulation in cultures treated with TSH plus retinol was lower than that of control cultures treated with TSH alone. However, iodide uptake stimulated by 8-bromo-cAMP was also inhibited by retinoids. Retinol reduced TSH- or 8-bromo-cAMP-stimulated gene expression of thyroid peroxidase. Thus, the data suggest that retinoids inhibit TSH-stimulated iodine metabolism by reducing cAMP accumulation and also by acting on the steps subsequent to cAMP production.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Falsely elevated serum parathyroid hormone levels due to immunoglobulin G in a patient with idiopathic hypoparathyroidism.

A 73-yr-old patient with idiopathic hypoparathyroidism was admitted to our hospital in May 1981. The immunoreactive PTH (iPTH) level determined by RIA using antiserum specific for the C-terminal region of PTH-(65-69) was in the upper normal range (0.6 ng/mL) and over the next 7 yr increased gradually to 6 ng/mL. Since iPTH levels determined using other commercial RIA kits remained constantly decreased or in the undetectable range, we studied the mechanism of false elevation of iPTH in this patient. The patient's serum contained no binding protein to the tracer ([125I]) [Tyr45] human PTH-(46-84)), nor was any heterophilic antibody to the first [guinea pig immunoglobulin G (IgG)] or the second antibody (goat IgG) detected. Consistent with these findings, the dilution curve of the serum was parallel with that of standard bovine PTH-(1-84). Gel filtration analysis revealed that the iPTH-like substance was eluted in the void volume (apparent mol wt, greater than 70,000). Almost all of the iPTH-like substance was adsorbod by a protein-A-Sepharose column. When the IgG fraction purified by protein-A-Sepharose affinity chromatography was applied to an antihuman IgG lambda-Sepharose column, 72% of the iPTH-like substance was detected in the IgG lambda. These results suggest that the falsely elevated iPTH in the patient's serum was due to IgGs (mainly IgG lambda), which were cross-reactive with the antiserum highly specific for the C-terminal region of human PTH-(65-69).

Aged↗
PubMed1991

Measurement of free form of insulin-like growth factor I in human plasma.

A method to measure free form of insulin-like growth factor I (IGF-I) in human plasma using octadecylsilyl silica (Sep-Pak C18) cartridge has been developed. IGF-I was adsorbed by Sep-Pak C18 cartridge and eluted with 75% ethanol--0.01 M HCl. Labeled and non-labeled IGF-I were recovered in yields 92.5 +/- 2.1% (Mean +/- SEM) and 94.4 +/- 6.3% after adsorption to and elution from the Sep-Pak, respectively. When EDTA plasma was applied to the Sep-Pak, less than 5% of total IGF-I was recovered in the eluate. However, when acid-ethanol extracted plasma was applied to the Sep-Pak, IGF-I was recovered in yields greater than 75% of total IGF-I. When the Sep-Pak eluate was gel filtered, 88.4 +/- 4.0% of immunoreactive IGF-I eluted in the same fraction as synthetic IGF-I did, but the fraction passed through the Sep-Pak was observed as a high molecular weight form (bound form) of IGF-I. These data indicate that this Sep-Pak method does not extract all of the IGF-I in plasma, but extracts mainly the free form IGF-I. Using this method, IGF-I values of free form (fIGF-I) in EDTA plasma were measured. The fIGF-I values in normal adults, patients with acromegaly, and patients with growth hormone (GH)-deficiency were 2.4 +/- 0.1, 13.8 +/- 1.6, and 1.1 +/- 0.1 ng/ml, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1991

Repeated sc administration of recombinant human insulin-like growth factor I (IGF-I) to human subjects for 7 days.

Recombinant human insulin-like growth factor I (rhIGF-I) was administered subcutaneously to 6 normal subjects and 2 patients with GH deficiency at a dose of 0.1 mg/kg for 7 consecutive days after breakfast. In normal subjects, plasma IGF-I levels increased from 217 +/- 22 ng/ml (Mean +/- SEM) to maximal levels of 581 +/- 6 ng/ml 4 h after the first administration of IGF-I. The blood glucose levels were statistically depressed 4 h after injection at 69 +/- 2 mg/dl. Similar plasma IGF-I and blood glucose profiles were observed after the seventh administration of IGF-I. The free form of IGF-I in plasma was 2.3 +/- 0.3 ng/ml in normal subjects and increased to maximal levels of 43.5 +/- 5.1 ng/ml 2 h after the first IGF-I administration. A similar pattern for the free form of IGF-I was observed after the seventh administration; however, the values obtained at 0, 1 and 2 h were greater after the seventh administration. In patients with G-deficiency, the plasma IGF-I and blood glucose profiles were similar to those observed in normal subjects, although the total IGF-I levels were low in these patients at all sampling points during the study. Slight decreases in serum insulin, uric acid, and creatinine were observed after the seventh administration of IGF-I. There were no changes in the excretion of urea nitrogen, creatine, creatinine, sodium, potassium, chlorine, calcium or C-peptide in the urine during the 7 days of IGF-I administration.

Adult↗
PubMed1990

Insulin-induced hypoglycemia, L-dopa and arginine stimulate GH secretion through different mechanisms in man.

We sought to clarify the mechanisms of growth hormone (GH) secretion induced by insulin hypoglycemia, L-dopa, and arginine in man. The secretion of GH as measured by increased plasma level, in response to oral administration of 500 mg L-dopa or 30 min-infusion of arginine, was not modified by prior intravenous administration of 200 micrograms GH-releasing hormone (GHRH). It was, however, completely blocked by preadministered 50 micrograms SMS201-995, a long-acting somatostatin (SRIH) analog. GH release with 200 micrograms GHRH was completely blocked by 100 micrograms SMS201-995. GH secretion caused by insulin-induced hypoglycemia was significantly reduced but still present after administration of 100 micrograms of the analog. These results suggest that a suppression of SRIH release may be partially involved in the stimulatory mechanism of GH secretion by L-dopa. Coadministration of GHRH accentuated the stimulatory effect of arginine on GH secretion. Arginine significantly raised plasma TSH levels. These findings suggest that arginine suppresses SRIH release from the hypothalamus to cause GH secretion because SRIH suppresses TSH secretion. It is also suggested that some factor (or factors) other than GHRH and SRIH are involved in the mechanism by which insulin-induced hypoglycemia stimulates GH secretion, because the effect of insulin was not fully blocked in the presence of SRIH analog. Thus all the tests for GH release appear to act via different mechanisms.

Adult↗
PubMed1990

Epidermal growth factor and transforming growth factor alpha induce ascitic fluid in mice.

Recent studies have suggested that pleural or peritoneal effusion associated with metastatic tumors is induced by some mediators produced by the tumor cells. We studied the ability of well-characterized peptide growth factors to produce ascites in mice. Peritoneal administration of epidermal growth factor (EGF, 10 to 40 micrograms/mouse/wk) or transforming growth factor alpha (TGF-alpha, 10 to 40 micrograms/mouse/wk) via osmotic minipumps resulted in formation of bloody ascites. The amount of ascites produced was dependent on the dose of growth factors. Vehicle alone or insulin-like growth factor I (40 micrograms/mouse/wk) was without effect. Indomethacin, a blocker of prostaglandin synthesis, significantly reduced the ascites accumulation induced by EGF, suggesting that prostaglandins are involved in ascites formation induced by EGF. Dexamethasone was also effective in attenuating the effect of EGF. Thus, it is possible that peritoneal effusion associated with disseminated tumors is, at least in part, due to EGF-like materials (most likely TGF-alpha) produced by tumor cells. The mechanism by which these peptides induce bloody ascites is not known for certain, but it may be due to the reported activity for neovascularization or increased vascular permeability.

Animals↗
PubMed1990

Insulin-like growth factor I and transforming growth factor alpha as autocrine growth factors in human pancreatic cancer cell growth.

The roles of insulin-like growth factor I (IGF-I) and transforming growth factor alpha (TGF-alpha) as autocrine factors in the proliferation of MIA-PaCa 2 cells (human pancreatic cancer cells, PC cells) were investigated. Furthermore, the mechanism(s) of inhibition of PC cell growth by a phorbol ester in relation to these two kinds of growth factor was also studied. PC cells grew autonomously when Dulbecco's modified essential medium supplemented with 4% fetal calf serum was changed to serum-free medium (0.3% bovine serum albumin-Dulbecco's modified essential medium). In addition, serum-free conditioned medium from PC cells dialyzed against fresh Dulbecco's modified essential medium had a stimulatory action on the growth of the same kind of cells when compared with that induced by nonconditioned medium. These observations suggest that a factor(s) produced and released by PC cells stimulates their own growth. Analysis of conditioned medium from PC cells revealed the presence of immunoreactive (IR)-IGF-I and IR-TGF-alpha. The molecular size of IR-IGF-I was similar to that of authentic IGF-I. On the other hand, IR-TGF-alpha was present as multiple forms when analyzed using gel chromatography. Authentic IGF-I and TGF-alpha added to culture medium stimulated PC cell growth by 1.45- and 1.5-fold above control value, respectively. A monoclonal antibody to IGF-I receptor was able to inhibit PC cell growth. PC cell proliferation was markedly inhibited by 12-O-tetradecanoyl-13-acetate (greater than 0.16 nm), whereas cell growth of human fibroblasts was stimulated by it. 12-O-Tetradecanoyl-phorbol-13-acetate also reduced the binding of 125I-TGF-alpha, but not 125I-IGF-I, to PC cells. Decrease in TGF-alpha binding was mainly due to the reduced affinity of receptors to the ligand. These results suggest that IGF-I and TGF-alpha are involved in PC cell proliferation as autocrine factors. Further, the inhibition of PC cell growth by phorbol ester could be, at least partly, due to the decreased binding of TGF-alpha to the cells.

Adult↗
PubMed1990

Prolonged and ubiquitous inhibition by interferon gamma of bone resorption induced by parathyroid hormone-related protein, 1,25-dihydroxyvitamin D3, and interleukin 1 in fetal mouse forearm bones.

To investigate the mechanism of the inhibitory effects of interferon-gamma (IFN-gamma) on bone resorption, the effects of murine IFN-gamma on 45Ca release from prelabeled fetal mouse forearm bones were investigated. Murine IFN-gamma usually did not affect basal 45Ca release but almost completely and equipotently inhibited bone resorption induced by PTH(1-34), PTH-rP(1-34), 1,25(OH)2D3, and interleukin 1 (IL-1). The half-maximal concentration for inhibition of bone resorption induced by IL-1 alpha was 25.8 +/- 14.6 U/ml (mean +/- SD for 13 experiments), which is not different from those for PTH, PTH-rP, and 1,25(OH)2D3. There was no correlation between prostaglandin E2 concentration in the conditioned medium and 45Ca release from the IFN-gamma-treated forearm bones. The inhibitory effect of IFN-gamma on bone resorption induced by PTH-rP (1-34) or IL-1 alpha continued during 6 days of culture, whereas that of calcitonin disappeared after 2 days of culture. These findings suggest that IFN-gamma non-preferentially inhibits bone resorption induced by various bone-resorbing factors in fetal mouse forearm bones via a PGE2-independent mechanism. As no escape phenomenon developed in IFN-gamma-treated bones, the cytokine may be potentially useful for treatment of certain patients with malignancy-associated hypercalcemia.

Animals↗
PubMed1990

Effects of endothelin on renal hemodynamics and excretory functions in anesthetized dogs.

The effects of endothelin on renal hemodynamics and excretory functions were investigated in anesthetized dogs. Infusion of endothelin at a rate of 1 ng/kg.min resulted in a slight but significant decrease in renal blood flow and an increase in renal vascular resistance and filtration fraction. Endothelin at doses higher than 10 ng/kg.min significantly decreased cardiac output, glomerular filtration rate, urine volume, and urinary sodium and potassium excretion, whereas it increased systemic vascular resistance. Mean arterial pressure and heart rate showed a transient decrease and increase, respectively, at doses higher than 50 ng/kg.min. Plasma renin activity and plasma aldosterone concentrations were increased only at the dose of 100 ng/kg.min. These effects lasted for more than 60 min. These results suggest that endothelin may have an important role in the modulation of renal functions as well as in the modulation of systemic hemodynamics.

Aldosterone↗
PubMed1990

Renal and hemodynamic effects of endothelin in anesthetized dogs.

The effects of endothelin on systemic hemodynamics and renal functions were investigated in anesthetized dogs. Infusion of endothelin at a dose of 1 ng/kg/min decreased renal blood flow and increased renal vascular resistance and filtration fraction. Endothelin at doses higher than 10 ng/kg/min significantly decreased cardiac output, glomerular filtration rate, renal plasma flow, urine volume, and urinary sodium excretion. Mean arterial pressure showed a transient decrease at doses higher than 50 ng/kg/min. These results showed that endothelin in systemic administration has effects on renal functions as well as on systemic hemodynamics.

Anesthesia↗
PubMed1990

Effects of short-term growth hormone therapy in short children without growth hormone deficiency.

Evaluation of 24-hour endogenous growth hormone (GH) secretion was carried out in 62 children, aged 7-16 years, who did not have classic GH deficiency (GHD). The mean 24-hour GH concentration, determined at 20-minute intervals over 24 hours, was variable, ranging from 1.28 to 11.39 micrograms/l with a mean of 4.95 +/- 2.55 micrograms/l (+/- SD). There was a positive correlation between mean 24-hour GH concentration and plasma insulin-like growth factor I (IGF-I) values (r = 0.54; p less than 0.01). Recombinant human GH, 0.1 IU/kg/day was administered to 30 of the 62 children for 6 months followed by 6 months' observation without treatment. Thereafter, GH was administered at the same dose for a further 6 months to 16 children. The mean height velocities before, during, and after the first treatment period were 4.3 +/- 0.9, 7.3 +/- 1.9 and 4.9 +/- 2.0 cm/year (mean +/- SD), respectively. The height velocity during treatment was greater than pre- and post-treatment values (p less than 0.001). The height velocity increased again during the second treatment period to a mean of 8.5 +/- 2.0 cm/year (p less than 0.001). Nine other children were treated continuously in a similar manner for 1 year and their height velocity increased significantly from 4.1 +/- 1.4 to 6.0 +/- 1.9 cm/year (p less than 0.001). According to our criteria, 29 of the 39 children (74.4%) who were treated for 6-12 months showed a GH-dependent height increase during therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Relationships between puberty and growth at adolescence in growth-hormone-deficient males: effect of growth hormone and of associated gonadal suppression therapy.

125 boys with idiopathic GH deficiency who received GH treatment were followed until they reached their final height. In 85 patients who had spontaneous puberty (group I), the mean final height was 151.5 +/- 6.6 cm. In 23 patients with combined GH and gonadotropin deficiency (group II) whose pubertal development was induced artificially at age 19.4 +/- 2.1 years, the mean final height was 163.7 +/- 3.9 cm (p less than 0.01 vs. group I). Final height was strongly related to height at the onset of pubertal development in combined groups I and II when the time of gonadal replacement treatment was taken as the onset of pubertal development in group II. In 17 patients (group III) who developed spontaneous puberty, gonadal suppression treatment was started at their early stage of puberty and was continued for a mean duration of 4.3 +/- 1.1 years. The mean final height in group III was 157.9 +/- 3.0 cm (p less than 0.01 vs. group I, group II). Longitudinal growth pattern analysis demonstrated that this beneficial effect on final height by gonadal suppression treatment was attributed to the elongation of pubertal growth spurt and pubertal height gain.

Adolescent↗
PubMed1990

Exogenous and locally synthesized angiotensin II and glomerulosa cell functions.

We conducted this study to examine the effects of exogenous and locally synthesized angiotensin II (Ang II) on cultured bovine glomerulosa cell functions (i.e., aldosterone secretion and cell proliferation measured by [3H] thymidine incorporation into the deoxyribonucleic acids (DNA) after the arresting cell growth). The effects of Ang II were found to depend on the culture conditions. After 72 hours of serum-free culture, the differentiated function of cultured cells such as Ang II-induced aldosterone secretion was suppressed, and DNA synthesis was stimulated by Ang II. After 24 hours of serum-free culture, the cells showed a good steroidogenic response and DNA synthesis was inhibited after Ang II was added in a concentration-dependent manner (10(-11) to 10(-7) M). Ang II was detected in 24 hours of culture grown in a serum-free medium by a specific Ang II radioimmunoassay. Ion-exchange high-performance liquid chromatography indicated that this immunoreactive (ir) Ang II was composed mainly of Ang II with small amounts of angiotensin III (Ang III). The concentration of irAng II in the cultured medium was significantly reduced by the addition of captopril, indicating de novo generation and secretion of Ang II. Captopril (10(-5) to 10(-3) M) reduced aldosterone secretion and reciprocally increased DNA synthesis. Ang II antagonist, [Sar1, Ile8] Ang II, increased DNA synthesis presumably by competitive blockade of locally synthesized Ang II. In summary, Ang II inhibited cell proliferation. In addition to exogenous (circulating) Ang II, Ang II was generated and secreted by the glomerulosa cells themselves, and this locally synthesized Ang II appeared to work as an autocrine factor to stimulate aldosterone secretion and to suppress cell proliferation.

Aldosterone↗
PubMed1990

Effect of lithium on deoxyribonucleic acid synthesis and iodide uptake in porcine thyroid cells in culture.

We investigated the direct effect of lithium on porcine thyroid cells in culture to exclude the secondary regulatory factors. First we have studied the effect of lithium on TSH-induced iodide uptake. Significant suppression was seen at 0.1 mmol/liter, and half-maximal suppression was obtained at the pharmacological concentration reported in patient serum. The suppression was dose dependent and reversible. Besides the suppression of cAMP production stimulated by TSH, lithium also inhibited iodide uptake stimulated by forskolin or 8-bromo-cAMP. These results demonstrated that lithium inhibits TSH-induced iodide uptake not only by reducing cAMP production, but also by acting on the steps of post-cAMP production. Next, we studied the effect of lithium on DNA synthesis of the cultured porcine thyroid cells. Lithium stimulated [3H]thymidine incorporation of the thyroid cells in the basal condition (0.5% fetal calf serum) as well as those stimulated by insulin-like growth factor-I (100 micrograms/liter). The minimal concentrations for the significant increase were 0.5 and 0.1 mmol/liter, respectively. These results suggest that lithium might contribute to the formation of the goiter directly at the cellular levels in patients treated with the agent.

Animals↗
PubMed1990

Inhibition of 125I organification and thyroid hormone release by interleukin-1, tumor necrosis factor-alpha, and interferon-gamma in human thyrocytes in suspension culture.

To elucidate the mechanism of decreased 131I uptake by the thyroid gland in patients with subacute thyroiditis and painless thyroiditis, human thyroid follicles were cultured with interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF alpha), and/or interferon-gamma (IFN gamma), and the effects of these cytokines on thyroid function were studied in vitro. When human thyrocytes were cultured in RPMI-1640 medium containing 0.5% fetal calf serum and TSH for 5-8 days, the cells incorporated 125I, synthesized de novo [125I]iodotyrosines and [125I]iodothyronines, and secreted [125I]T4 and [125I]T3 into the medium. IL-1 alpha and IL-1 beta inhibited 125I incorporation and [125I]iodothyronine release in a concentration-dependent manner. The minimal inhibitory effect was detected at 10 pg/ml. Electron microscopic examination revealed a marked decrease in lysosome formation in IL-1-treated thyrocytes. TNF alpha and IFN gamma also inhibited thyroid function in a concentration-dependent manner. Furthermore, when thyrocytes were cultured with IL-1, TNF alpha and IFN gamma, these cytokines more than additively inhibited thyroid function. Although the main mechanism of 131I uptake suppression in the thyroid gland in subacute thyroiditis is due to cellular damage and suppression of TSH release, our present findings suggest that IL-1, TNF alpha, and IFN gamma produced in the inflammatory process within the thyroid gland further inhibit iodine incorporation and at least partly account for the decreased 131I uptake by the thyroid gland in destruction-induced hyperthyroidism.

Cells, Cultured↗
PubMed1990

Effects of sc administration of recombinant human insulin-like growth factor I (IGF-I) on normal human subjects.

Recombinant human insulin-like growth factor I (IGF-I) was administered subcutaneously to each of 5 normal human subjects at doses of 0 mg/kg (control), 0.06 mg/kg, or 0.12 mg/kg successively at one week intervals. After 0.06 mg/kg or 0.12 mg/kg IGF-I injections, plasma IGF-I levels increased from 185 +/- 17 ng/ml (mean +/- SEM) to maximal levels of 396 +/- 21 ng/ml at 3 hours and from 169 +/- 14 ng/ml to 480 +/- 27 ng/ml at 4 hours, respectively. These two peak values were statistically different (p less than 0.05). After 0.06 mg/kg and 0.12 mg/kg IGF-I administration, blood glucose levels decreased from 85 +/- 2 mg/dl to minimal levels of 73 +/- 3 mg/dl at 3 hours and from 83 +/- 1 mg/dl to 50 +/- 4 mg/dl at 2 hours, respectively. These two minimal values were statistically different (p less than 0.001). Serum insulin and C-peptide levels were decreased in a dose dependent manner after IGF-I administration. There were no changes between blood urea nitrogen levels before and 4 hours after IGF-I administration. The urinary GH concentration decreased after 0.06 mg/kg IGF-I administration, but increased and maintained normal values after 0.12 mg/kg IGF-I administration.

Adult↗