Search PubMed⌕ Search

Biomedical subjects

T Tsushima

Publications and source records attributed to T Tsushima.

At least 55 records · Page 3Linked to original sources
PubMed1998

Growth hormone and prolactin stimulate tyrosine phosphorylation of insulin receptor substrate-1, -2, and -3, their association with p85 phosphatidylinositol 3-kinase (PI3-kinase), and concomitantly PI3-kinase activation via JAK2 kinase.

Growth hormone (GH) and prolactin (PRL) binding to their receptors, which belong to the cytokine receptor superfamily, activate Janus kinase (JAK) 2 tyrosine kinase, thereby leading to their biological actions. We recently showed that GH mainly stimulated tyrosine phosphorylation of epidermal growth factor receptor and its association with Grb2, and concomitantly stimulated mitogen-activated protein kinase activity in liver, a major target tissue. Using specific antibodies, we now show that GH was also able to induce tyrosine phosphorylation of insulin receptor substrate (IRS)-1/IRS-2 in liver. In addition, the major tyrosine-phosphorylated protein in anti-p85 phosphatidylinositol 3-kinase (PI3-kinase) immunoprecipitate from liver of wild-type mice was IRS-1, and IRS-2 in IRS-1 deficient mice, but not epidermal growth factor receptor. These data suggest that tyrosine phosphorylation of IRS-1 may be a major mechanism for GH-induced PI3-kinase activation in physiological target organ of GH, liver. We also show that PRL was able to induce tyrosine phosphorylation of both IRS-1 and IRS-2 in COS cells transiently transfected with PRLR and in CHO-PRLR cells. Moreover, we show that tyrosine phosphorylation of IRS-3 was induced by both GH and PRL in COS cells transiently transfected with IRS-3 and their cognate receptors. By using the JAK2-deficient cell lines or by expressing a dominant negative JAK2 mutant, we show that JAK2 is required for the GH- and PRL-dependent tyrosine phosphorylation of IRS-1, -2, and -3. Finally, a specific PI3-kinase inhibitor, wortmannin, completely blocked the anti-lipolytic effect of GH in 3T3 L1 adipocytes. Taken together, the role of IRS-1, -2, and -3 in GH and PRL signalings appears to be phosphorylated by JAK2, thereby providing docking sites for p85 PI3-kinase and activating PI3-kinase and its downstream biological effects.

Androstadienes↗
PubMed1998

Growth factors increase pericellular proteoglycans independently of their mitogenic effects on A10 rat vascular smooth muscle cells.

Proliferation of vascular smooth muscle cells with the accumulation of proteoglycans in the extracellular matrix is one of the significant changes found in atherosclerotic lesions. In order to clarify the relationship between pericellular proteoglycan and cell growth, we established a simple method for quantitatively estimating the amount of pericellular proteoglycans and investigated the effects of various growth factors on the synthesis of pericellular proteoglycans by cultured A10 rat smooth muscle cells. Analysis of trypsin accessible [35SO4]-labeled material in the pericellular area of the A10 cell culture by Q-sepharose anion-exchange chromatography showed two peaks. One peak, eluted at 0.55 M NaCl, disappeared after treatment with 2 mU/ml of heparitinase, indicating that heparan sulfates (HS) were present. The other peak, which eluted at 0.65 M NaCl, disappeared with 20 mU/ml of chondroitinase ABC, indicating the presence of chondroitin sulfates and dermatan sulfates (CS/DS). We estimated the effects of several growth factors on the synthesis of the pericellular proteoglycans by measuring heparitinase- and chondroitinase-ABC-sensitive radioactivities. Although PDGF-AB significantly stimulated cell proliferation and the synthesis of pericellular CS/DS, its dose-dependent effect on the cell growth did not coincide with that on the proteoglycan synthesis. IGF-I (1 nM) increased pericellular CS/DS but not the cell number, while basic FGF (1 nM) and EGF (1 nM) increased the cell number but not pericellular CS/DS. All the growth factors we examined had no effect on the synthesis of pericellular HS. These results indicate that growth factors increase pericellular proteoglycans independently of their mitogenic effects.

Animals↗
PubMed1998

Clinical evaluation of serum prostate-specific antigen-alpha1-antichymotrypsin complex values in diagnosis of prostate cancer: a cooperative study.

BACKGROUND: We studied the clinical significance of serum prostate-specific antigen bound to alpha1-antichymotrypsin (PSA-ACT) values determined with a newly developed enzyme immunoassay. METHODS: Serum PSA-ACT values were determined in a total of 652 sera. Clinical utility for the diagnosis of prostate cancer was compared to that of Tandem-R PSA and gamma-seminoprotein (gamma-Sm). The new enzyme immunoassay is based on the use of the Stanford reference as an international standard for PSA assays. RESULTS: Serum PSA-ACT values ranged from less than 0.10 to 1.4 ng/mL in healthy males (n = 100) while values in patients with benign prostatic hyperplasia (n = 155) averaged 3.4 +/- 3.8 ng/mL (mean +/- SD). In patients with prostate cancer, serum PSA-ACT values increased significantly with progression of the clinical stage and there were statistically significant differences between benign prostatic hyperplasia and each stage of prostate cancer except for stage A. Using BPH levels as controls (4.8 ng/mL for PSA-ACT, 7.2 ng/mL for PSA, 3.8 ng/mL for gamma-Sm, and 2.4 ng/mL for the complexed/free PSA ratio of PSA-ACT/gamma-Sm), specificity was 80%. The sensitivity of prostate cancer detection was 79% for PSA-ACT, 77% for PSA, 57% for gamma-Sm, and 46% for the ratio between PSA-ACT/gamma-Sm. CONCLUSION: Although the determination of serum PSA-ACT showed essentially the same utility as that of PSA for the diagnosis of prostate cancer, PSA-ACT may allow prediction of the clinical stage. The PSA-ACT assay may therefore replace PSA in the detection of prostate cancer.

Disease Progression↗
PubMed1998

Absorption of epirubicin instilled intravesically immediately after transurethral resection of superficial bladder cancer.

As postoperative adjuvant therapy for superficial bladder cancer, intravesical instillation therapy is commonly conducted. In this case, from the view point of prevention of intraoperative dissemination, commencement of instillation therapy at an early postoperative period is preferred. However, increased drug permeability is suspected because of damage to the bladder mucosa during operation. Therefore, this study was conducted to investigate the plasma level of epirubicin (EPI) instilled immediately after transurethral operation. EPI (20 mg/40 ml or 50 mg/100 ml) was instilled immediately after a transurethral operation, and retained in the bladder for 1 h. Blood samples were obtained before instillation, as well as 30, 60, 120 and 240 min after instillation, and EPI levels were assayed. The mean EPI concentrations (ng/ml) among the 20-mg/40 ml group (n = 5) were < 2.5 and < 2.0 at 30 and 60 min, respectively, after which they were undetectable. The 50-mg/100 ml group (n = 5) recorded 5.0, 4.4 and < 3.0 after 30, 60 and 120 min, respectively, and after 240 min it was undetectable. Intravesical instillation of EPI immediately after a transurethral operation causes a small increase in the plasma level and it is thought to cause small systemic side effects.

Absorption↗
PubMed1998

Effect of growth hormone (GH) on serum concentrations of leptin: study in patients with acromegaly and GH deficiency.

As leptin, an ob gene product, plays a pivotal role in the regulation of adiposity and energy homeostasis, the level of its expression is likely to fluctuate under various physiological, nutritional, and disease conditions. Reports regarding the effect of GH on serum leptin levels are inconsistent. We have measured serum leptin levels and correlated them with several variables in patients with acromegaly, patients with adult GH deficiency (GHD), and normal controls. In 116 normal subjects, the mean serum concentration of leptin was 5.0+/-2.8 (mean +/- SD) ng/mL in men (n = 42) and 10.7+/-7.3 ng/mL in women (n = 73), respectively. As reported previously, the leptin levels in women were significantly (P < 0.001) higher than in men, and there was a strong positive correlation between log-transformed serum leptin levels and percent body fat in simple regression analysis (in men: r = 0.606; P < 0.0001; in women: r = 0.707; P < 0.0001). In 36 acromegalic patients, the percent body fat mass was significantly lower than that in normal subjects, and the mean serum leptin level was 2.2+/-1.8 ng/mL in men (n = 18) and 3.6+/-2.5 ng/mL in women (n = 18). Analysis of covariance revealed that serum leptin levels in acromegalics were significantly lower than those in normal subjects after correcting percent body fat (P = 0.016 for men and P < 0001 for women). In male patients with GHD (n = 20), the mean percent body fat was significantly (P < 0.05) higher than that in age-matched controls, whereas the value in female GHD patients (n = 15) did not differ from that in age-matched controls. Serum leptin levels in GHD patients were 5.1+/-2.5 ng/mL in men and 11.5+/-8.1 ng/mL in women, which were not different from those in normal subjects adjusted for percent body fat mass. In multiple regression analysis models with log-transformed leptin as the dependent variable, gender, percent body fat (or body fat mass), and serum insulin-like growth factor I levels entered the equations at a statistically significant level. These data suggest that excess GH/insulin-like growth factor I reduces serum leptin levels by reducing body fat mass and/or by unknown mechanisms.

Acromegaly↗
PubMed1998

Registration system for growth hormone (GH) treatment with standardized immunoreactive GH values in Japan.

The Foundation for Growth Science has been controlling the use of GH by its registration system, which includes a scoring system for the eligibility for GH treatment according to the diagnostic criteria for GH deficiency (GHD) established by the Study Group for Hypothalamo-pituitary Disorder of the Ministry of Health and Welfare. Until 1995, 28,876 patients with GHD (19,432 boys and 9,444 girls) had been registered as eligible for GH treatment. The number of patients registered in a year increased gradually till 1990 due to the unlimited hGH supply by recombinant techniques and the change in the criteria for GH treatment and the number registered became stable after 1990. The frequency of GH-treated patients is calculated to be 55.2/100,000 persons (72.2/100,000 in boys and 37.1/100,000 in girls) in patients born between 1960 and 1990. The highest frequency was 148.4/100,000 persons (191.7/ 100,000 boys and 103.7/100,000 girls) in 1981, when 2,278 patients (1,508 boys and 770 girls) were born. Eligibility for GH treatment is assessed according to the scoring system which is basically dependent on peak GH values in provocation tests so that standardization of GH values measured with the various commercial GH kits is required to avoid inequality of patients' access to the treatment. In samples obtained by GRF test in 10 normal volunteers, hGH was measured with seven human GH (hGH) kits at a laboratory center. Since the RIA value has been used historically for the diagnosis of GHD, the mean of two RIA measurements was selected as the basis for the standardization procedure and the linear regression formula was used for each hGH kit. After the freely available supply of hGH obtained by recombinant DNA techniques, the role of the Foundation for Growth Science has changed to avoid hGH abuse. Even with this regulation, the frequency of registered patients may indicate a tendency to GH overuse.

Child↗
PubMed1998

Growth hormone-induced tyrosine phosphorylation of EGF receptor as an essential element leading to MAP kinase activation and gene expression.

GH binding to its receptor, which belongs to the cytokine receptor superfamily, activates Janus kinase (JAK) 2 tyrosine kinase, thereby activating a number of intracellular key proteins such as STAT (signal transducers and activators of transcription) proteins and mitogen-activated protein (MAP) kinases, which finally lead to GH's biological actions including gene expression. In contrast to receptor tyrosine kinases, the signalling pathways leading to MAP kinase activation by GH are poorly understood but appear to involve Grb2 and Shc. We now show that GH stimulated tyrosine phosphorylation of epidermal growth factor receptor (EGFR) and its association with Grb2, and concomitantly stimulated MAP kinase activity in liver, a major target tissue. Expression of EGFR and its mutants into CHO-GH receptor (GHR) cells revealed that GH-induced full activation of MAP kinase and c-fos expression required tyrosine phosphorylation sites of EGFR but not its intrinsic tyrosine kinase activity. Moreover, by also using dominant negative JAK2 and in vitro kinase assay, we demonstrated that tyrosine 1068 of EGFR was evidently one of the major phosphorylation and Grb2 binding sites stimulated by GH via JAK2. These data suggest that the role of EGFR in GH signalling is to be phosphorylated by JAK2, thereby providing docking sites for Grb2 and activating MAP kinases and gene expression. This novel cross talk pathway may provide the first example of the hormone and cytokine receptor superfamily transducing signals via associated nonreceptor tyrosine kinase by phosphorylating growth factor receptor and utilizing it as a docking protein independent of its receptor tyrosine kinase activity.

Adaptor Proteins, Signal Transducing↗
PubMed1998

[Combination chemotherapy with cis-platinum and ifosfamide for hormone unresponsive prostate cancer].

PURPOSE: There is no effective therapy against hormone refractory prostate cancer. This led us to evaluate the effectiveness and toxicity of cis-platinum (CDDP) and ifosfamide (IFM) combination chemotherapy in the patients with hormone-unresponsive carcinoma of the prostate. METHODS: Patients with hormone-unresponsive prostate cancer were scheduled to receive CDDP 70 mg/m2 intravenously on day 1 and IFM 1.2 g/m2/day intravenously on day 1 through day 5 of 28-day cycle. RESULTS: Twenty seven patients with hormone unresponsive prostate cancer were enrolled onto this trial. Of these patients, seven (26%) demonstrated a partial objective response (PR), and ten (37%) a stable disease (ST). The response duration of PR cases lasted from 6 to 49 months with a median of 16 months and the response duration of PR + ST cases lasted from 3 to 36 months with a median of 10 months. Subjective improvement was obtained in 11 patients (41%). Survival duration of all cases were 4 to 89 months with a median of 23 months and probabilities of survival at 3 years and 5 years were 36% and 24%, respectively. The toxicity of this treatment was mostly mild to moderate, anemia (96%), leukocytopenia (89%), anorexia (81%), alopecia (67%), thrombocytopenia (44%), hematuria (38%), renal dysfunction (19%) and liver dysfunction (7%) were noticed. Severe toxicity was observed in two cases, one acute renal failure and one endotoxin shock. CONCLUSION: We conclude that CDDP and IFM combination chemotherapy was active regimen for hormone unresponsive prostate cancer.

Aged↗
PubMed1998

[A case of squamous cell carcinoma of the lung associated with exophthalmos and hypercalcemia].

A 69-year-old man visited in the department of ophthalmology of this university, complained with exophthalmos. He was pointed out hypercalcemia and transferred to the department of endocrinology. The chest X-ray and thoracic CT showed a large mass in lower lobe of the left lung. Cytological diagnosis of this tumor was squamous cell carcinoma. In clinical examination, serum CA was 12.2 mg/dl in spite of normal level of PTH, calcitonin, 1 alpha, -25 (OH) 2D3 and uric cAMP. On the other hand, PTHrP-intact in serum was 9.8 pmol/l. His thyroid gland had no abnormality in palpation or roentogenological examination. The thyroid functions, thyroglobulin, thyrotropin receptor antibody, thyroid test and microsome test were all in normal limit. From these results, he was diagnosed of lung cancer with humoral hypercalcemia of malignancy and euthyroid "isolated" Graves' ophthalmopathy. Left lower lobectomy with mediastinal lymph node dissection (R 2 a) was done and p-stage was IIIA. After operation, serum Ca decreased in normal level and the exophthalmos was also improved gradually. He was in well until 10 months after operation, and died with multiple lung metastases and hypercalcemia. Exophthalmos was also recurred in his terminal stage. Similar case could not find in literature and some discussion of the literatures was mentioned.

Aged↗
PubMed1998

[Clinical studies of tazobactam/piperacillin (TAZ/PIPC) in pediatric patients].

Tazobactam/Piperacillin (TAZ/PIPC) is a newly developed intravenous antibiotics, in which TAZ, a new potent inhibitor of beta-lactamases, is combined with PIPC, a well-established beta-lactam antibiotics, at the ratio of 1:4. In this study, we clinically evaluated efficacy of the drug in 14 pediatric patients with various infections, and pharmacokinetic study was applied to 3 patients. Range of age was from 1-month to 15 1/4-year. Patients consisted of 9 cases of pneumonia, 3 urinary tract infection, 1 acute otitis media, and 1 left sacroiliitis with sepsis. Standard dose of TAZ/PIPC was 50 mg/kg/dose and administered 2-4 times per day with intravenous injection or drip infusion. Two cases of pneumonia were excluded because of non-bacterial infection. Nine causative pathogens including 3 Gram-positive cocci and 6 Gram-negative bacilli were detected in 7 patients, of which 5 Gram-negative strains produced bete-lactamase. All of cases showed 100% of efficacy rate and bacteriological eradication rate. It was noted that beta-lactamase-producing E. coli and B. catarrhalis were eradicated efficiently by TAZ/PIPC, which should be resistant to PIPC alone according to MIC data. Non-serious diarrhea and discomfort of back with nausea were observed in one each patients as side effects. Both of side effects were transient, and improved with anti-diarrheic agent or cessation of the drug, respectively. As abnormal laboratory test results, moderate increases of the eosinophils and platelets counts as well as moderate elevation of the transaminases were observed in 2 separate patients. Pharmacokinetics study showed that Cmax, T1/2, and AUC were similar to the data reported in adult patients. Urinary recovery rate in the first 6 hours also resemble the data from adult patients. Based on above results, TAZ/PIPC is a useful agents pediatric infections by beta-lactamase producing strains also.

Adolescent↗
PubMed1998

[Chemotherapy for hormone-refractory prostate cancer].

Chemotherapy may be an appropriate treatment for patients with evidence of disease progression despite of antiandrogen withdrawal or secondary hormonal therapy. But none of the chemotherapeutic regimens, neither monotherapy nor combination therapy, were shown to be superior to another with regard to survival. The criteria to assess the effect of chemotherapy on disease-related symptoms and quality of life is expected to be framed. Preclinical investigations and well-designed, well-powered clinical trials remain key to altering the natural history of hormone-refractory prostate cancer.

Antineoplastic Agents↗
PubMed1997

Synthesis and structure-activity relationships of dual histamine H2 and gastrin receptor antagonists with decreased hydrophobicity.

In order to study structure-activity relationships of the previously reported dual histamine H2 and gastrin receptor antagonists and also to improve their low oral absorbability, we tried two chemical modifications. One tried to decrease the high hydrophobicity of the parent hybrid compounds to an appropriate level by incorporating a hydrophilic group into the molecule and the other by replacing the more hydrophobic groups with less hydrophobic ones. The former compounds (type I) involved hybrid compounds with a hydroxyl group at a position of a spacer, a piperidine moiety of H2A, or a phenyl ring at the C5 of the benzodiazepine skeleton as well as those with a free carboxyl group in the piperidine moiety of H2A. The latter (type II) involved hybrid compounds with the C5-phenyl group replaced with either a methyl group or hydrogen atom. Among them, only a type I compound, ([2-[3-(3-piperidin-1-ylmethylphenoxy)propylcarbamoyl] ethylcarbamoyl]methyl)carbamic acid 3-[3-[5-(3-hydroxyphenyl)-1-methyl-2-oxo-2,3-dihydro-1H-1,4-benzodiaz epin-3-yl]ureido]benzyl ester (18), showed potent dual histamine H2 and gastrin receptor antagonistic activity, whereas others resulted in a significant decrease of histamine H2 receptor antagonistic activity. The in vivo gastric acid antisecretory activity of 18 evaluated by Schild's rat method, however, did not suggest any notable improvement in oral absorbability.

Animals↗
PubMed1997

Synthesis and structure-activity relationships of dual histamine H2 and gastrin receptor antagonists with modified benzodiazepine skeletons.

Three different types of dual histamine H2 and gastrin receptor antagonists, e.g. those bearing a benzazepine, benzoxazepine, or benzothiazepine skeleton instead of the benzodiazepine one as a gastrin receptor antagonistic moiety were synthesized to reduce high hydrophobicity of parent compounds and evaluated for the dual activities. These skeletal modifications significantly potentiated the binding affinity of dual antagonists with histamine H2 receptor but markedly diminished their binding affinity with the gastrin receptor and the gastrin versus CCK-A receptor selectivity. We evaluated in vivo gastric acid antisecretory activities for some representative compounds by the rat pylorus ligation method for 10 mg kg(-1) dose by oral route. However, they exerted only low inhibitory activities for oral dose with % inhibition values ranging between 32 and 53%.

Animals↗
PubMed1997

Synthesis and structure-activity relationships of dual histamine H2 and gastrin receptor antagonists with noncyclic gastrin receptor antagonistic moieties.

In order to study structure-activity relationships of dual histamine H2 and gastrin receptor antagonists as well as to improve their low oral absorbability, their prototype benzodiazepine gastrin receptor antagonistic moieties were altered to a conformationally flexible noncyclic dipeptide equivalent. This skeletal modification significantly potentiated the binding affinity of hybrid compounds for the histamine H2 receptor, whereas their affinity for the gastrin receptor and receptor selectivity over the CCK-A receptor varied widely with the substituents on the gastrin moiety. Among them, [3-[3-(3-piperidin-1-ylmethylphenoxy)propylcarbamoyl]p ropyl carbamic acid 3-[3-([(3-methoxyphenyl)[(methylphenylcarbamyl)methyl]carbamoyl]me thyl)ureido]benzyl ester (7a) showed the highest dual histamine H2 and gastrin receptor antagonistic activities. It also displayed distinct gastric acid antisecretory activity in vivo for two assays, namely, Schild's rat method by i.d. administration and the rat pylorus ligation method by oral administration. With the latter case, dose-response relationships were observed for the first time, suggesting its substantially improved oral absorbability. However, 7a did not display distinct in vivo gastric acid antisecretory activity for the assay with Heidenhain pouch dogs.

Absorption↗
PubMed1997

Oncostatin M: a new potent inhibitor of iodine metabolism inhibits thyroid peroxidase gene expression but not DNA synthesis in porcine thyroid cells in culture.

The functions of thyroid cells are regulated by a number of cytokines and growth factors in addition to TSH. Recent studies have revealed that several cytokines including interleukin (IL)-6 are involved in thyroid dysfunction. Oncostatin M (OSM) is a glycoprotein belonging to the same family of cytokines as IL-6, to which it is related by sequence and structural homology and the use of the signal-transducing receptor component gp130. We, therefore, studied the effect of OSM on iodide uptake and DNA synthesis by porcine thyroid cells in culture. OSM increased c-fos and c-jun mRNA levels but did not stimulate DNA synthesis. OSM inhibited iodide uptake stimulated by TSH; while IL-6 also inhibited iodide uptake, it was only about one-tenth as potent. IL-6 had about the same potency as OSM when it was added with soluble IL-6 receptor. OSM had no effect on cAMP production but inhibited iodide uptake stimulated by 8-bromo-cAMP and forskolin. These findings suggest that OSM exerts its inhibitory effects at the post-cAMP production step(s). OSM also inhibited thyroid peroxidase mRNA levels but had little effect on thyroglobulin mRNA levels. Investigations of the signal transduction system showed that gp130 and leukemia inhibitory factor (LIF) receptor beta subunit mRNA were detectable in porcine thyroid cells by reverse transcription (RT)-polymerase chain reaction (PCR). Together with the report that serum OSM and IL-6 concentrations are elevated to the same levels in patients with sepsis, these results suggest that OSM may contribute to the thyroid dysfunction in this condition.

Animals↗
PubMed1997

Preoperative endocrine therapy for clinical stage A2, B, and C prostate cancer: an interim report on short-term effects. Prostate Cancer Study Group.

BACKGROUND: Preoperative endocrine therapy has been suggested to improve surgical radicality and/or patient prognosis in prostate cancer. METHODS: Patients with clinical stage A2, B, and C prostate cancer were randomized to either group I (n = 113) or group II (n = 111). Group I patients were to receive preoperative endocrine therapy consisting of leuprolide and chlormadinone for 3 months, followed by radical prostatectomy with lymph node dissection. Group II patients were to undergo the surgery before endocrine therapy. RESULTS: Group I patients showed a remarkable decrease in prostate-specific antigen (PSA) (mean +/- SE: 41.8 +/- 8.6 ng/mL to 2.7 +/- 0.7 ng/mL) and prostate volume (29.8 +/- 1.7 mL to 21.2 +/- 1.6 mL) during the preoperative therapy. Histopathologic analysis showed a significant difference in the rates of down-staging (19.1% in group I versus 3.3% in group II), positive surgical margins (63.8% versus 81.3%) and positive lymph node metastasis (20.7% versus 36.5%). No significant difference was detected in operating features. Subgroup analyses indicated that beneficial effects were correlated positively with degree of histologic differentiation and negatively with the basal PSA level. CONCLUSIONS: Preoperative endocrine therapy reduced local extension of prostate cancer, and the effects depended on histologic differentiation and PSA level. Long-term follow-up data are needed to determine the effects on the patient prognosis.

Aged↗