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Biomedical subjects

J Takahara

Publications and source records attributed to J Takahara.

At least 19 recordsLinked to original sources
PubMed1992

Stimulatory effects of quinpirole hydrochloride, D2-dopamine receptor agonist, at low concentrations on prolactin release in female rats in vitro.

Dopamine (DA) has dual actions (inhibitory and stimulatory) in the regulation of prolactin (PRL) release, depending on its concentration. To investigate the stimulatory effects of DA, perifused rat anterior pituitary cells were exposed to the highly-specific DA D2 receptor agonist, quinpirole hydrochloride (LY). Very low concentrations of LY (10(-12)-10(-10) M) stimulated PRL release and potentiated thyrotropin-releasing hormone (TRH)-induced PRL release. Higher concentrations of LY did not stimulate. Pretreatment with pertussis toxin (30 ng/ml, 24 h) completely abolished these effects of LY. The D2 receptor antagonist, metoclopramide, also blocked the potentiation by LY of TRH-induced PRL release. These data indicate that very low concentrations of dopamine stimulate PRL release via an interaction with a D2 receptor connected to a pertussis toxin-sensitive G protein.

Animals↗
PubMed1992

Acute myelocytic leukemia associated with thrombocytosis and inv 3(q21.3; q26.2) in a case of Grönbland-Strandberg syndrome.

Grönbland-Strandberg syndrome is an inherited connective tissue disorder with cutaneous, ophthalmologic, and systemic manifestations. Here we report a case of AML with thrombocytosis arising in a patient with this syndrome. Karyotypic analysis of bone marrow cells revealed the inversion 3 (q21.3;q26.2). To our knowledge, this is the first report of the association of AML with thrombocytosis and Grönbland-Strandberg syndrome. This might be a coincidental association, but it suggests some interesting speculations regarding the pathogenesis of these diseases.

Chromosome Inversion↗
PubMed1992

Corticotropin releasing factor and galanin-containing neurons projecting to the median eminence of the rat.

To identify corticotropin releasing factor (CRF)- and galanin (GAL)-containing neurons projecting to the median eminence, a retrograde tracing method with True blue was combined with a double-staining method. It was demonstrated that some True blue-labeled CRF neurons in the paraventricular nucleus were also immunoreactive for GAL. These findings support the hypothesis that GAL and CRF are simultaneously involved in regulation of ACTH secretion from the anterior pituitary.

Adrenocorticotropic Hormone↗
PubMed1992

Activity of antibiotics against resistant Pseudomonas aeruginosa.

The activity of 12 antibiotics, piperacillin, cefazolin, cefotiam, ceftizoxime, latamoxef, ceftazidime, cefuzonam, amikacin, ofloxacin, imipenem, aztreonam and minocycline, against 120 isolates of Pseudomonas aeruginosa was examined. In addition, the efficacy of antibiotics against single-, double-, or triple-drug-resistant isolates of P. aeruginosa were also examined to determine the cross-resistance to each drug. There was cross-resistance between piperacillin, ceftazidime and aztreonam, but amikacin and imipenem remained effective antibiotics, especially as salvage therapy, against isolates resistant to one agent. Results also suggested that piperacillin, ceftazidime or imipenem in combination with amikacin are effective combination regimens against most clinical isolates of P. aeruginosa. Amikacin and imipenem were also suitable antibiotics, especially as salvage therapy, against isolates of P. aeruginosa resistant to two agents. In conclusion, the results provide useful guidelines for choosing an effective treatment against clinical isolates of P. aeruginosa, and for choosing salvage therapy against resistant P. aeruginosa.

Amikacin↗
PubMed1992

Identification of dopamine and growth hormone-releasing factor-containing neurons projecting to the median eminence of the rat by combined retrograde tracing and immunohistochemistry.

The topographical location of tyrosine hydroxylase (TH) neurons, a marker for dopamine neurons in the hypothalamus, that project to the median eminence was identified with immunofluorescence staining in combination with retrograde transblue, indicating that they projected to the median eminence. Only a few retrogradely labeled TH cells were observed in the periventricular nucleus and the lateral basal hypothalamus. The elution restaining procedure revealed that an average of 32% of the labeled TH cells in the ventrolateral portion of the ARC contained GRF. These findings support the hypothesis of co-expression of dopamine with GRF from the ARC.

Animals↗
PubMed1992

Post-splenectomy meningitis in patients with lymphoid malignancy.

This report describes pneumococcal meningitis in two splenectomized patients with lymphoid malignancy. Early diagnosis and emergency treatment of pneumococcal infection in splenectomized patients is proven to be of significant value. Prophylactic antibiotics targeted against pneumococcus should be considered for the clinical management of such conditions in splenectomized patients, particularly during cytotoxic chemotherapy.

Adult↗
PubMed1992

[Pilot phase II trial of high-dose etoposide combined with cisplatin in the treatment of refractory lung cancer].

The efficacy of combined high-dose etoposide with standard dose cisplatin was evaluated in patients who had refractory lung cancer after standard chemotherapy. Each patient was given etoposide at 500 mg/m2/day on day 1 to 3 continuously (total dose 1,500 mg/m2) and cisplatin at 80 mg/m2 on day 1. Fifteen patients (7 adenocarcinoma, 5 small cell lung cancer, 2 squamous cell lung cancer and 1 sarcoma, which latter was difficult to distinguish from giant cell carcinoma) were entered in this study. The overall response was 41.7% (5 of 12); five partial response, 6 no change, and 1 progressive disease. Three treatment-related deaths were observed; one resulted from sepsis and two from respiratory failure because of tumor progression. All of the patients developed severe myelosuppression; the mean nadir white blood cell count was 400, and the mean nadir platelet count was 24,000 in 28 evaluable courses. The range of maximum concentration of etoposide determined by HPLC was from 17.4 to 39.1 micrograms/ml. These results suggest that high-dose etoposide combined with a standard dose of cisplatin is effective against refractory lung cancer.

Adenocarcinoma↗
PubMed1992

[Nosocomial respiratory infection caused by Pseudomonas cepacia in immunocompromised hosts].

Pseudomonas cepacia is a gram negative rod, having no fermentative activity on glucose. This organism was detected in the sputum, throat swab, or throat washing of 22 inpatients treated between January, 1990, and December, 1990, at the First Department of Internal Medicine, Kagawa Medical School. The primary diseases for which these 22 patients were hospitalized were leukemia in 12, malignant lymphoma in 5, lung cancer in 2, myelodysplastic syndrome in 1, and embryonal cell carcinoma in 1. Twelve of the 22 patients had episodes of pneumonia which complied clinically with the diagnostic criteria provided to facilitate the National Nosocomial Infection Study. The complication of pneumonia occurred in 7 patients with leukemia, 2 with malignant lymphoma, 2 with lung cancer, and 1 with myelodysplastic syndrome. In 10 of these 12 patients, the organism was detected before the onset of pneumonia. All 22 patients in whom the organism was demonstrated had received antibiotics. The antibiotics which was most frequently used to treat these patients 1 month before detection of Pseudomonas cepacia were amikacin and ceftizoxime, which were used in 13 patients. Of the antibiotics in which the susceptibility to Pseudomonas cepacia was, evaluated, minocycline was effective in 100% (21/21), ceftazidime in 50% (11/22), and ofloxacin in 27.3% (6/22). Physicians should be especially aware of the possibility of colonization and nosocomial respiratory infection by Pseudomonas cepacia in patients with severe underlying diseases.

Adolescent↗
PubMed1992

E. coli gpt gene expression effects on K562 human leukemia cell proliferation and erythroid differentiation altered by mycophenolic acid.

Inosine monophosphate dehydrogenase (IMPDH, EC 1.1.1.205) inhibitors including mycophenolic acid (MPA) were reported to induce K562 human leukemia cells to differentiate into erythroid cells. A shuttle vector plasmid pMSG containing E. coli xanthine-guanine phosphoribosyl transferase (Eco gpt) gene was transfected into K562 cells (K562-pMSG cells) to investigate the role of IMPDH in both K562 cell proliferation and erythroid differentiation. Eco gpt provides K562 cells with an additional salvage pathway for GMP production from xanthine. In the presence of xanthine, K562-pMSG cells continued to proliferate and did not differentiate to erythroid cells regardless of the presence of MPA, but they discontinued proliferating and differentiated into the erythroid lineage in the absence of xanthine. Proliferation and differentiation of control K562 cells into erythroid cells were suppressed by MPA regardless of the presence or absence of xanthine. Addition of guanosine maintained the proliferation and blocked the erythroid differentiation of K562 and K562-pMSG cells induced by MPA even in the absence of xanthine. These data indicate that a decrease in the activity of IMPDH and a subsequent decline in the concentration of guanine nucleotides caused by MPA resulted in the induction of the erythroid differentiation and discontinuation of the proliferation of K562 cells.

Blotting, Southern↗
PubMed1991

Neurotensin and growth hormone-releasing factor-containing neurons projecting to the median eminence of the rat: a combined retrograde tracing and immunohistochemical study.

The origins of the neurotensin (NT)-containing nerve terminals in the median eminence were determined in rats by a combination of retrograde labeling with True blue and immunofluorescence staining. Moreover, the distribution of NT and growth hormone-releasing factor (GRF) was analyzed in the arcuate nucleus (ARC) with an elution-restaining procedure. The retrogradely labeled NT neurons were found mainly in the ARC. Only a few labeled NT neurons were seen in the periventricular and the paraventricular nuclei. The elution restaining procedure demonstrated that an average of 43% of the labeled NT cells in the ventral part of the ARC restained for GRF. These findings support the hypothesis of co-expression of NT with GRF from the ARC.

Animals↗
PubMed1991

Induction of erythroid differentiation of K562 cells by 4-carbamoylimidazolium 5-olate (SM-108).

The effects of 4-carbamoylimidazolium 5-olate (SM-108), an antipurine compound, on a human leukemia cell line, K562, were studied. Treatment with SM-108 induced erythroid differentiation of K562 cells. During a 6-day culture with 100 microM SM-108, the cell number decreased to 37% of the control number, 77% of the cells became benzidine-positive, and the hemoglobin content increased from 2.1 +/- 0.2 to 10.6 +/- 1.3 pg/cell. Cell differentiation was associated with reduction of IMP dehydrogenase activity and intracellular GTP content to 25 and 36%, respectively, of the control values within 1.5 hr. The differentiation and decrease in the GTP pool induced by SM-108 were blocked by the presence of 25 microM guanine or guanosine. SM-108 also induced erythroid differentiation of K562 subline cells transfected with pMSG (K562/pMSG), which have an additional salvage pathway for GMP production from xanthine. The addition of 100 microM xanthine prevented erythroid differentiation of this subline and restored the GTP pool. These findings suggest that the induction of erythroid differentiation of K562 cells by SM-108 may be due to an early decrease in IMP dehydrogenase activity and a subsequent decrease in GTP content in the cells. Thus, purine metabolism may have an important role in SM-108-induced differentiation.

Cell Differentiation↗
PubMed1991

Characterization of the stimulatory effect of galanin on growth hormone release from the rat anterior pituitary.

The present study was undertaken to investigate the direct actions of rat galanin (R-GAL) on growth hormone (GH) release from the rat anterior pituitary in vitro. R-GAL modestly but significantly stimulated GH release without an increase in intra- and extracellular cyclic AMP levels in monolayer cultures of rat anterior pituitary cells. This stimulatory effect of R-GAL was dose-dependent but not additive with that of GH-releasing factor (GRF). R-GAL-stimulated GH release was less sensitive to the inhibitory effect of somatostatin than was GRF-stimulated GH release. In perfusions of rat anterior pituitary fragments, R-GAL induced a gradual and sustained increase of GH release. Incremental GH release derived in part from preformed stored GH. These data confirm that R-GAL acts at the pituitary level to stimulate GH release by a mechanism distinct from that of GRF.

Animals↗
PubMed1991

[Two cases of Trichosporon beigelii pneumonia in immunocompromised hosts].

Two cases of Trichosporon beigelli pneumonia in severely immunocompromised patients are reported. At autopsy, Trichosporon beigelii was detected in all lobes in one patient who had a small cell lung cancer. Polymycotic infection involving Trichosporon beigelii and Aspergillus was proved in the other patient who had a non-Hodgkin's lymphoma. Miconazole therapy was not effective against Trichosporon beigelii infection in both cases. Although diagnosis and management are difficult, Trichosporon beigelii must be considered as a cause of visceral opportunistic fungal infection.

Aged↗
PubMed1990

Immunohistochemical identification of galanin and growth hormone-releasing factor-containing neurons projecting to the median eminence of the rat.

Through the combined demonstration of the retrograde transport of True blue and the immunohistochemical staining of galanin (GAL), the GAL neurons that project to the median eminence were identified. Moreover, the distribution of GAL and growth hormone-releasing factor (GRF) was analyzed in the arcuate nucleus (ARC) with an elution-restaining procedure. Following the injection of True blue into the median eminence, GAL-positive cells labeled with True blue were found mainly in the ARC. In addition, a few GAL neurons in the periventricular, the paraventricular and the supraoptic nuclei were labeled with True blue. The elution-restaining results revealed that many retrogradely labeled GAL neurons in the ARC contained GRF. These findings suggest that a subpopulation of GAL neurons in the ARC sending axons to the median eminence produces, stores and releases a GRF-like peptide.

Animals↗
PubMed1988

Physiological role of growth hormone (GH)-releasing factor and somatostatin in the dynamics of GH secretion in adult male rat.

To investigate the physiological role of GRF and somatostatin (SRIF) in GH secretion in adult male rats, we prepared in vitro models using the perifusion system of cultured rat anterior pituitary cells exposed to various combinations of human GRF-(1-44)NH2 (hGRF) and SRIF. We studied the following three models on GRF secretion: 1) pulsatile GRF secreted at 1-h intervals, 2) pulsatile GRF secreted at 3-h intervals, and 3) GRF continuously secreted. When 5-min pulses of 20 nM GRF were delivered at 1-h intervals, the responses to GRF gradually declined. The addition of continuous 20 nM SRIF with short pauses prevented this attenuated response and produced high peaks of GH at 3-h intervals. When 5-min pulses of 20 nM GRF were delivered at 3-h intervals, three high peaks of GH were observed regardless of the addition of SRIF. Pretreatment with GRF pulses enhanced the peaks of GH during SRIF pauses. When 20 nM GRF was continuously delivered, a rapid attenuated response to GRF was observed. Although the addition of continuous 20 nM SRIF with short pauses produced three small peaks of GH, these results were caused by the post-SRIF rebound release. These observations suggest that preexposure to prolonged SRIF can prevent an attenuated response to repeated GRF pulses, and that pretreatment with GRF pulses enhances post-SRIF rebound release.

Animals↗
PubMed1985

Effects of age on GH responses to growth hormone-releasing factor in rats.

This paper aims to investigate the growth hormone (GH) responses to the growth hormone releasing factor-44 (GRF-44) in young and adult rats in vitro and in vivo. Male Wistar rats aged 28 days and 6 months were used. In pentobarbital anesthetized young rats, an intravenous administration of GRF-44 at a dose of 25 ng/100 g b.w. resulted in an 11.4 fold rise in the serum GH level at 5 min after GRF-44 injection. On the other hand, in adult rats the same dose of GRF-44 did not elicit a significant rise in the serum GH level. However, GH secretion in response to GRF-44 at a dose of 250 ng/100 g b.w. was not attenuated in adult rats. Isolated pituitary cells obtained from young and adult rats were incubated for 3 days. The addition of GRF-44 at a concentration of 5 ng/ml to the cultured pituitary cells from young rats caused a 3.2 fold increase in GH content in the medium. On the other hand, the same dose of GRF-44 added to the cultured pituitary cells from adult rats resulted in only a 2.3 fold increase in GH content. These data indicate that the sensitivity of somatotrophs to GRF may be diminished with age.

Aging↗