Some actions of taurine on ionic currents of myocardial cells and myometrial cells.
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Animals↗
Biomedical subjects
M Kusaka
Publications and source records attributed to M Kusaka.
Effects of recombinant human granulocyte colony-stimulating factor on the growth potential of two murine myeloid leukemias.
We investigated the in vitro and in vivo effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on the proliferation of two murine leukemic cell lines. The rhG-CSF stimulated leukemic colony formation of the promyelocytic leukemic cell line L-8801 in methylcellulose culture and increased the number of L-8801 cells in liquid culture. However, rhG-CSF treatment prolonged the median survival period of mice implanted with L-8801 cells and the emergence of the leukemic blast cells in peripheral blood. Meanwhile, rhG-CSF had no influence on that of the megakaryoblastic leukemic cells L-8057 and failed to prolong the median survival period of L-8057 leukemic mice. Receptor binding analysis revealed that L-8801 cells expressed a G-CSF receptor (Kd=125 pM, 479 binding sites/cell) and L-8057 cells had no G-CSF receptors. Then, we examined the growth potential of these cells. The median survival period was longer for mice implanted with L-8801 cells cultured with rhG-CSF for 72 h in vitro than for cells grown without rhG-CSF. Furthermore, the median survival period of mice implanted with spleen cells from L-8801 leukemic mice treated with rhG-CSF was prolonged compared with those from leukemic mice without rhG-CSF. In contrast, there was no effect of rhG-CSF on the growth potential of the spleen from L-8057 leukemic mice. The results of our present study demonstrate that rhG-CSF reduced the growth of L-8801 leukemic cells in vitro and in vivo mediated through G-CSF receptors, thereby suppressing the development of leukemia.
Animals↗
Effect of recombinant human thrombopoietin in nonhuman primates with chemotherapy-induced thrombocytopenia.
We examined the effects of recombinant human thrombopoietin (rhTPO) on myelosuppressive chemotherapy-induced thrombocytopenia in cynomolgus monkeys. After treatment with nimustine (ACNU) on day 0, the monkeys intravenously received rhTPO at a dose of 0.04, 0.2 or 1 microgram/kg/d or monkey's serum once each day from day 1 to day 28. Administration of rhTPO reduced the severity of thrombocytopenia and accelerated the rate of platelet recovery in a dose-dependent fashion. Treatment with the highest rhTPO dose completely prevented thrombocytopenia and stimulated a marked increase in platelet counts over the normal values. Animals treated with ACNU also became neutropenic and slightly anaemic. Administration of rhTPO following ACNU treatment significantly improved neutropenia with increasing doses of rhTPO, but had no effect on anaemia. Compared to the control animals, rhTPO-treated animals exhibited no significant changes in several serum parameters. C-reactive protein concentration and some blood coagulation profiles within the study period. These results suggest a therapeutic efficacy of rhTPO in improving chemotherapy-induced thrombocytopenia.
Animals↗
Stimulation of Ca2+ current by phorbol esters in rat myometrial cells is dependent on intracellular Ca2+ concentration.
The effects of phorbol esters on the L-type Ca2+ current (ICa(L)) were investigated using nystatin-perforated patch and standard whole-cell voltage clamp in uterine smooth muscle cells isolated from late-pregnant rats. Using nystatin-perforated patch to maintain the integrity of the cytosol components, phorbol 12-myristate 13-acetate (PMA, 300 nM) increased ICa(L). When the standard whole-cell voltage clamp was used, the effect of PMA was dependent on the Ca2+ concentration in the pipette solution: PMA enhanced ICa(L) at pCa 6 and pCa 7 but not at pCa 10 or pCa 8. The effect of PMA was reversed by a selective inhibitor of protein kinase C, calphostin-C (500 nM). It is concluded that phorbol esters stimulate ICa(L) in uterine muscle cells and that the isoform of protein kinase C involved in this effect is Ca2+ dependent. This mechanism may be involved in the regulation of uterine contraction during pregnancy.
Animals↗
Simultaneous measurement of proguanil and its metabolites in human plasma and urine by reversed-phase high-performance liquid chromatography, and its preliminary application in relation to genetically determined S-mephenytoin 4'-hydroxylation status.
A simple high-performance liquid chromatographic (HPLC) assay method was developed for the measurement of proguanil (PG) and its major metabolites, cycloguanil (CG) and 4-chlorophenyl-biguanide (CPB), in human plasma and urine. The assay allowed the simultaneous determination of all analytes in 1 ml of plasma or 0.1 ml of urine. The detection limits of PG, CG, and CPB, defined as the signal-to-noise ratio of 3, were 1 and 5 ng/ml for plasma and urine samples, respectively. Recoveries of the analytes and the internal standard (pyrimethamine) were > 62% from plasma and > 77% from urine. Intra-assay and interassay coefficients of variation for all analytes in plasma and urine were < 10% except for the values of CG and CPB, which ranged from 10% to 15% at one or two concentrations among 4-5 concentrations studied. The clinical applicability of the method was assessed by the preliminary pharmacokinetic study of PG, CG, and CPB in six healthy volunteers with the individually known phenotypes (extensive and poor metabolizers) of S-mephenytoin 4'-hydroxylation, suggesting that individuals with a poor metabolizer phenotype of S-mephenytoin have a much lower capacity to bioactivate PG to CG compared with the extensive metabolizers.
Adult↗
Management conditions during dialysis therapy influence the occurrence of complications after renal transplantation?
We investigated whether the management condition of patients during dialysis therapy has an influence on the occurrence of complications after renal transplantation. Thirty-one patients who underwent renal transplantation were investigated: thirteen received kidneys from living related donors and 18 received cadaveric transplants. The relations between weight gain ratio, cardiothoracic ratio (CTR) and blood pressure during dialysis and the rate of episodes of acute rejection or infection after renal transplantation were analyzed. The rate of acute rejection tended to be higher among patients whose CTR was less than 45% than in those whose CTR was 45% or more. There was no relation found between the rate of infection after transplantation and weight gain ratio. CTR, or blood pressure during dialysis therapy. These results suggest the possibility that the management condition of patients during dialysis therapy influences the rate of acute rejection after these patients undergo renal transplantation.
Adolescent↗
Improvement of thrombocytopenia following bone marrow transplantation by pegylated recombinant human megakaryocyte growth and development factor in mice.
We examined whether pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) is capable of improving thrombocytopenia and promoting thrombopoietic reconstitution following lethal irradiation and bone marrow transplantation (BMT) in mice. Immediately after receiving 10 Gy whole body irradiation (day 0), male C3H/HeN mice were inoculated with 10(6) bone marrow cells obtained from syngeneic mice. Circulating platelet counts decreased to below 4% of the normal counts with a nadir on day 10, and then returned to the normal level on day 28 in the control mice undergoing BMT. Subcutaneous consecutive treatment with PEG-rHuMGDF at doses from 10 to 300 micrograms/kg/day from day 1 for 13 days significantly improved the platelet nadir and promoted platelet recovery. The white blood cell counts and hemoglobin concentration following BMT were not influenced by the PEG-rHuMGDF. PEG-rHuMGDF-injection starting from day 5 did not improve the platelet nadir following BMT. Furthermore, administration with PEG-rHuMGDF on alternate days at 55.7 micrograms/kg/day for 7 days or at an interval of 3 days at 78 micrograms/kg/day for 4 days (twice a week for 2 weeks) had a significant efficacy, but these administration regimens had less efficacy than consecutive administration at 30 micrograms/kg/day for 13 days. The numbers of megakaryocytes and megakaryocyte progenitor cells decreased to 5 and 0.2% of normal level, respectively, in the control mice. Consecutive administration of PEG-rHuMGDF enhanced the recovery of the mean number of these cells compared to those in vehicle-treated mice, although such effects were not statistically significant except for the number of megakaryocyte progenitors on day 12. These results suggest that consecutive treatment with PEG-rHuMGDF beginning from the day after BMT may be effective in improving thrombocytopenia following BMT.
Animals↗
Inhibition of L-type calcium current by genistein, a tyrosine kinase inhibitor, in pregnant rat myometrial cells.
Possible regulation of L-type Ca2+ channels by tyrosine kinase was examined in freshly isolated uterine smooth muscle cells obtained from late pregnant (18-19 day) rat, using whole-cell voltage clamp. Bath application of genistein, an inhibitor of tyrosine kinase, decreased L-type Ca2+ current (ICa(L)) dose-dependently. The maximal inhibition of ICa(L) was 46% and the concentration for half-maximal inhibition (IC50) was 50 microM (at a holding potential of -60 mV). The effect of genistein was reversible. Daidzein, an inactive analog of genistein, had no inhibitory effect on ICa(L) at concentrations as high as 300 microM. The steady-state inactivation curve for ICa(L) was shifted to the left by genistein (15 mV at 100 microM), whereas the activation curve was not affected, suggesting that genistein exerts.a voltage-dependent block. These results suggest that the L-type Ca2+ channels in myometrial cells may be modulated by endogenous tyrosine kinase, i.e., they are in a tonically stimulated state due to tyrosine kinase activity. This modulatory mechanism may play a role on the regulation of Ca2+ influx and uterine contraction during normal labor and preterm labor.
Animals↗
Improvement of anemia in W/WV mice by recombinant human erythropoietin (rHuEPO) mediated through EPO receptors with lowered affinity.
We studied the effects of recombinant human erythropoietin (rHuEPO) on anemic W/WV mice which manifested severe anemia accompanied by mutation of the W gene encoding tyrosine kinase type receptor (c-kit gene) of bone marrow hematopoietic cells. Nine-week-old male W/WV mice or normal littermates (+/+) were used. Since serum EPO concentration in W/WV mice increased in proportion to severity of anemia, EPO production in the kidneys of these animals was found to be regulated normally. Hematocrit in +/+ mice increased and a maximal response was also obtained with 2,000 IU/kg of rHuEPO. On the other hand, hematocrit in W/WV mice increased in a dose-responsive manner by administration with 2,000 and 10,000 IU/kg, showing different responses to rHuEPO in these two types of mice. The responsiveness of W/WV mice to rHuEPO was low in terms of increases in erythroblastic precursor cells (CFU-E), and immature cells in the bone marrow. Scatchard analysis of the specific binding of 125I-rHuEPO against bone marrow cells revealed that the different responsiveness to rHuEPO between W/WV and +/+ mice may be correlated with differences in affinity of EPO receptor of bone marrow cells in these mice. From these results, a high dose of rHuEPO is capable of improving the anemia in W/WV mice that had EPO receptors with lowered affinity, indicating the possible effectiveness of rHuEPO in anemic patients with EPO receptor abnormality.
Anemia↗
Metabolic disposition of proguanil in extensive and poor metabolisers of S-mephenytoin 4'-hydroxylation recruited from an Indonesian population.
1. The metabolism of proguanil (PG) was studied by measuring PG, cycloguanil (CG) and 4-chlorophenylbiguanide (CPB) in plasma and urine samples after an oral 200 mg dose of PG hydrochloride administered to 14 extensive (EMs) and 10 poor hydroxylators (PMs) of S-mephenytoin of Indonesian origin. 2. The mean ( +/- s.d.) values of the elimination half-life (t 1/2) and AUC of PG were significantly (P < 0.01) greater in the PM than in the EM group (20.6 +/- 3.1 vs 14.6 +/- 3.5 (95% confidence intervals of difference 3.1 to 8.9) h; and 5.43 +/- 1.89 vs 3.68 +/- 0.83 (0.58 to 2.91) micrograms ml-1 h). 3. Plasma concentrations of CG, an active metabolite, could not be detected in all PMs, and those of CPB were sufficiently high to determine a time-course in only four PMs. Mean AUC(0,24 h) values of CPB were significantly (P < 0.05) lower in the PM (n = 4) than in the EM group (n = 14) (0.47 +/- 0.13 vs 0.88 +/- 0.50 (-0.14 to 0.96) micrograms ml-1 h). 4. Log10 percentage urinary recovery of 4'-hydroxymephenytoin correlated significantly (P < 0.05) with the t 1/2 (rs = -0.661) and AUC (rs = -0.652) of PG. 5. PG, CG and CPB were detectable in urine at 12 h in all subjects. Log10 percentage urinary recovery of 4'-hydroxymephenytoin correlated significantly (P < 0.01) with urinary PG/CG (rs = -0.876), PG/CPB (rs = -0.833) and PG/(CG + CPB) (rs = -0.831) metabolic ratios.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Transient expression of type I collagen in glomeruli with anti-Thy-1 antibody-induced mesangial proliferative lesions.
Glomerular expression of extracellular matrices at the protein and mRNA levels was examined in rats with mesangial proliferative glomerulonephritis induced by the intravenous administration of a monoclonal anti-rat Thy-1 antibody. In close association with the mesangial proliferative lesion, type I collagen was immunostained at day 8 but not demonstrated at day 28 in the glomeruli of the kidneys. Type I collagen mRNA expression prominently increased in the nephritic glomeruli at day 4, prior to the appearance of type I collagen protein. In addition, fibronectin expression was also elevated in the diseased glomeruli at both the protein and mRNA levels. These results indicated that glomerular, probably mesangial cells, change their phenotypes during this disease, to synthesize abnormal extracellular matrices that lead to the progression of glomerular sclerosis.
Animals↗
[Pharmacological properties of chitosan-coated dialdehyde cellulose (chitosan DAC), a newly developed oral adsorbent (I). Effect of chitosan DAC in normal rats].
The effects of chitosan-coated dialdehyde cellulose (chitosan DAC), a newly developed oral adsorbent of urea and ammonia, were examined in an in vitro adsorption study and in normal rats. Chitosan DAC showed high adsorption capacity for urea and ammonia in an in vitro study using the diluted supernatant of rat gastrointestinal fluid. In contrast, Kremezin, an oral charcoal adsorbent (AST-120), had little influence on these substances. In normal rats fed diets containing chitosan DAC (1, 2, 3, 4, 5, 7, and 10% content) for three weeks, increases in fecal wet weight, fecal dry weight and fecal water content were observed in a dose-dependent manner. In addition, chitosan DAC feeding increased fecal excretion of nitrogen and electrolytes (sodium, potassium and chloride ions) and decreased the apparent protein ratio in a dose-dependent manner. There were no obvious effects in serum parameters except that increased levels of protein and albumin and decreased levels of blood urea nitrogen, cholesterol and glucose were observed in rats fed a high concentration of chitosan DAC. In conclusion, these findings suggest the possibility that chitosan DAC treatment might be effective for improving chronic renal failure.
Administration, Oral↗
[Pharmacological properties of chitosan-coated dialdehyde cellulose (chitosan DAC), a newly developed oral adsorbent (II). Effect of chitosan DAC on rats with chronic renal failure induced by adriamycin].
The effects of chitosan-coated dialdehyde cellulose (Chitosan DAC), a newly developed oral adsorbent of urea and ammonia, were examined in rats with progressive chronic renal failure (CRF) induced by adriamycin. CRF rats induced by repeated injections of adriamycin were fed a diet containing chitosan DAC (5% content) or Kremezin (5% content), an oral charcoal adsorbent (AST-120) under strict paired-feeding for four months. CRF rats that received both a normal diet and Kremezin showed progressive azotemia, hyperphosphatemia, hyperlipidemia, proteinuria, and anemia, and began to die from 9 weeks after feeding started. In contrast, chitosan DAC-treatment showed marked prolongation of the survival period and decreases in blood urea nitrogen, serum creatinine, and serum phosphate. In addition, chitosan DAC-treatment ameliorated anemia in CRF rats, although hyperlipidemia and proteinuria were not improved. Furthermore, fecal weight, fecal water content, fecal nitrogen and fecal sodium were markedly increased, and the apparent protein ratio was decreased in CRF rats fed a diet containing chitosan DAC for 9 weeks. In contrast, none of these effects were observed in CRF rats receiving Kremezin. These observations suggest the further possibility of using oral adsorbent therapy for CRF patients.
Administration, Oral↗
Direct block of calcium channels by dioctanoylglycerol in pregnant rat myometrial cells.
The effect of 1,2-dioctanoyl-sn-glycerol (DiC8), a diacylglycerol and potent protein kinase C (PKC) activator, on the voltage-dependent slow (L-type) Ca2+ current [lCa(L)] was examined using whole-cell voltage clamp of myometrial cells freshly isolated from late pregnant rats. Bath application of DiC8 (25 microM) decreased ICa(L) by 50.7 +/- 2.4% (n = 22). The effect was reversible and dose dependent (IC50 of 15.3 microM). The effect of DiC8 was not reversed or prevented by application of calphostin C, a selective PKC inhibitor. In addition, 1-oleoyl-2-acetyl-sn-glycerol, another PKC activator, did not produce an inhibitory effect on ICa(L), even at a concentration of 100 microM; ICa(L) was actually slightly stimulated (10.6 +/- 5.1%, n = 6). The steady state inactivation curve for ICa(L) was shifted to the left by DiC8 application (by approximately 15 mV at 25 microM), whereas the activation curve was not affected; the shift should produce a voltage-dependent block. DiC8 decreased ICa(L) progressively during repetitive step depolarizations (use-dependent block). We conclude from these results that (a) DiC8 inhibits ICa(L) independently of PKC in uterine muscle cells and (b) DiC8 preferentially acts on the inactivated state and/or open state of the L-type Ca2+ channels. Therefore, caution must be exercised when studying PKC actions on ion channel regulation using DiC8 as a PKC activator.
Animals↗
[Autoimmune hemolytic anemia reactivated by alpha-interferon therapy in a case of chronic active C-type hepatitis].
A case with autoimmune hemolytic anemia (AIHA) induced by interferon-alpha (IFN-alpha) is presented. A 40-year-old male who had a previous history of autoimmune hemolytic anemia, agranulocytosis and thrombocytopenia was admitted to our hospital because of chronic C type hepatitis. Liver biopsy was performed, which diagnosed chronic active hepatitis and IFN-alpha was administrated at a dose of 3 Meg unit per day. 11 days after the initiation of the therapy he developed hemolytic anemia, but Coombs tests were negative. Although IFN was withdrawn 15 days later, anemia became progressively more serious. 20 days later, both direct and indirect Coombs tests became positive. He was diagnosed as AIHA and treated with methylprednisolone pulse therapy, then he recovered soon afterward. Further analysis of Coombs tests revealed that he had both cold type and warm type (IgG) autoantibodies which was the same type of antibodies for AIHA he suffered 10 years ago. In conclusion, latent AIHA may be reactivated by the treatment with IFN-alpha.
Adult↗
Beneficial effect of 15-deoxyspergualin on accelerated rejection in rat heart transplantation.
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Animals↗
Experimental study on safety for granulopoiesis in simultaneous therapy with recombinant human granulocyte colony-stimulating factor and chemotherapy.
Since recombinant human granulocyte colony-stimulating factor (rhG-CSF) recruits hematopoietic progenitor cells into the cell cycle, the possibility remains that simultaneous injection of rhG-CSF and chemotherapeutic agents may aggravate the chemotherapy-induced neutropenia by sensitizing normal progenitor cells to the cytotoxic effects of chemotherapeutic agents. Therefore, the use of rhG-CSF is usually restricted from the day after chemotherapy. In the present study, we investigated whether concurrent treatment with rhG-CSF and chemotherapeutic agents aggravated granulopoietic failure, using murine neutropenic models. Neutropenia induced by a single injection of cyclophosphamide, mitomycin C, adriamycin, vincristine, combination of mitomycin C+vincristine, or combination of cyclophosphamide+vincristine+adriamycin (CHOP) was not aggravated by simultaneous injection of rhG-CSF (30 micrograms/kg, SC). In contrast, a single concurrent injection of rhG-CSF and 5-fluorouracil aggravated the neutropenia and the decrease in marrow colony-forming unit-granulocyte/macrophage counts, but simultaneous and following injections of rhG-CSF enhanced the recovery of neutrophils. Moreover, neutropenia induced by successive treatment with cisplatin was prevented by concurrent treatment with rhG-CSF during the period of the chemotherapy. From these results, concurrent treatment with rhG-CSF and chemotherapeutic agents with the exception of 5-fluorouracil may be feasible and well-tolerated in clinical use.
Animals↗
Veratridine actions on two types of fast Na+ channels in human uterine leiomyosarcoma cells.
In human uterine leiomyosarcoma cell line (SK-UT-1B), we previously demonstrated two types of fast Na+ current (INa(f)) induced by serum, based on different time course of current decay: fast-inactivating and slow-inactivating. To further clarify the properties of these currents, we studied the effects of veratridine, which is known to modify the inactivation process of INa(f), using whole-cell voltage clamp. Bath application of veratridine (100 microM) produced a decrease in peak INa(f) (Ipeak), simultaneous with increase in the steady-state current (Iss) and tail current (Itail). These effects of veratridine were observed in only slow-inactivating INa(f). The induction of Iss and Itail was completely reversed by washout of veratridine within 5 min, whereas the decreased Ipeak did not recover even after 15 min of washout. These findings suggest that the fast Na+ channels in this cell line may have two binding sites for veratridine: a high-affinity site, involved in the decrease in Ipeak (possibly due to a decrease in conductance), and a low-affinity site, related to the appearance of Iss and Itail (due to a long opening of the channels). It is concluded that the two types of INa(f) in this cell line have different sensitivity to veratridine and the fast Na+ channels may have two binding sites for veratridine.
Female↗