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Biomedical subjects

Y Asano

Publications and source records attributed to Y Asano.

At least 415 records · Page 23Linked to original sources
PubMed1994

Deficiency of tyrosine phosphorylation in a Balb/c 3T3 cell variant hypersensitive to phorbol ester-induced cell transformation.

To identify the cellular factors which are involved in tumor promotion, we isolated and cloned a Balb/c 3T3 variant (designated Balb/c 3T3 TR4) showing hypersensitivity to phorbol ester-induced neoplastic cell transformation; variant cells were 50- to 100-fold more sensitive to phorbol ester induced cell transformation than the parent Balb/c 3T3 A31-1-1 cells. By using an anti-phosphotyrosine antibody, the variant TR4 cells were found to be deficient in the phorbol ester-induced tyrosine-phosphorylation of a cellular protein with a mol. wt of 66 kDa. The phosphorylation of this protein was rapidly induced by phorbol ester tumor promoters on tyrosine residues in the parent 1-1 cells. Biological and biochemical analyses using fusion cells revealed a good correlation between the deficiency in the tyrosine phosphorylation of this protein and their sensitivity to phorbol ester-induced cell transformation, suggesting that the deficiency in phorbol ester-induced tyrosine phosphorylation of the 66 kDa protein may be involved in the determination of the sensitivity of TR4 variant cells to phorbol ester-mediated neoplastic cell transformation. In addition, our observations suggest the possible involvement of the modulation of tyrosine phosphorylation of cellular proteins in the process of phorbol ester-mediated tumor promotion.

3T3 Cells↗
PubMed1994

A novel form of self tolerance dictated in the thymus of transgenic mice with autoreactive TCR alpha and beta chain genes.

Transgenic (TG) mice with TCR alpha and beta chain genes from a CD4-dependent auto-I-Ak reactive T cell clone were generated. H-2k TG mice had a large number of thymic and splenic CD4 T cells expressing the autoreactive TCR without manifestation of autoimmunity. The cells were not anergic, as they could respond to autologous antigen presenting cells and anti-TCR antibodies in vitro to proliferate and to produce interleukins. Various degrees of down-regulation of CD2 and CD44 was observed in TG mice, indicating the presence of a defective co-stimulatory process in TG T cells. These features indicate that the self tolerance in autoreactive TCR TG mice is due not to clonal deletion and anergy but to a novel mechanism where T cells cannot sufficiently respond to normally existing self ligand in vivo. That such an in vivo unresponsiveness of autoreactive T cells is dictated in the thymus during CD4 T cell differentiation atypical form of positive selection of autoreactive T cells was suggested by the abnormal surface expression of CD69 and HSA.

Animals↗
PubMed1994

Prevention of TCR-mediated apoptosis by the elevation of cAMP.

The stimulation through TCR-CD3 complexes by immobilized anti-CD3 antibody induced the production of IL-2 and activation-induced cell death (ACD) in the majority of T cell hybridomas. However, some hybridomas produced IL-2 without showing any signs of ACD by the same stimulation, indicating that TCR-CD3-mediated signaling pathways of IL-2 production and of ACD are different. These pathways were discriminated from each other by protein kinase inhibitors and cAMP-elevating reagents such as forskolin. The pathway of IL-2 production but not of ACD was inhibited by protein kinase inhibitors. On the other hand, various cAMP-elevating reagents prevented the T cell hybridomas from TCR-mediated ACD with minimal inhibition of IL-2 production. The elevated cytoplasmic cAMP did not block dexamethasone-induced apoptosis. This indicates that apoptosis is regulated by multiple pathways. Furthermore, the inhibitory effect of cAMP is specific for the TCR-mediated signaling pathway of ACD. Messenger RNA for bcl-2 was detected after treatment with forskolin.

Animals↗
PubMed1994

Mechanisms of the hyperkalaemia caused by nafamostat mesilate: effects of its two metabolites on Na+ and K+ transport properties in the rabbit cortical collecting duct.

1. The present experiments were undertaken to determine the mechanism(s) of hyperkalaemia caused by nafamostat mesilate (NM), a serine-protease inhibitor. 2. We investigated the effects of luminal addition of two metabolites of NM, p-guanidinobenzoic acid (PGBA) and 6-amidino-2-naphthol (AN), on Na+ and K+ transport properties of the collecting duct (CD) cell in the isolated perfused cortical collecting duct (CCD) from rabbit kidneys, because these metabolites, but not NM, were mainly excreted into the urine. 3. Addition of PGBA at 10(-5) and 10(-4) M in the lumen resulted in a hyperpolarization of VA in parallel with increases in transepithelial resistance (RT) and fractional apical membrane resistance (fRA). PGBA added to the luminal perfusate at 10(-5) and 10(-4) M changed VA, RT and fRA in a dose-dependent manner. These effects were completely inhibited by pretreatment with luminal amiloride (50 microM). PGBA at 10(-6) M in the lumen had no effect on the electrical parameters. 4. Luminal addition of AN at 10(-4) M also caused the apical membrane to hyperpolarize in parallel with increases in RT and fRA. These effects were also completely inhibited by pretreatment with luminal amiloride (50 microM). AN at 10(-5) M in the lumen had no effect on the electrical parameters. 5. We conclude that two metabolites of NM, PGBA and AN, act on the apical membrane of the CD cell and inhibit the amiloride-sensitive Na+ conductance, resulting in an inhibition of K+ secretion. This direct action of these metabolites, rather than NM, on the CCD might contribute to the NM-induced hyperkalaemia.

Animals↗
PubMed1994

[Clinical evaluation of aciclovir granules in the treatment of chickenpox in otherwise healthy children].

The efficacy and safety of aciclovir granules (containing 40% w/w aciclovir) were evaluated in the treatment of chickenpox in otherwise healthy children. Patients presenting with chickenpox received aciclovir granules at a dose of 20 mg/kg four times daily for five to seven days. Overall 51 children received treatment with aciclovir. A further 53 patients receiving conventional symptomatic therapy acted as a control. In the aciclovir group the overall efficacy rate was 92.2%. There were reductions in the numbers of lesions, fever, itching and the duration of symptoms. No adverse experiences were reported. Overall this formulation of aciclovir appears to be a safe and effective treatment for chickenpox in this patient population. However the need for anti-viral therapy in otherwise healthy children is still the subject of debate and it might be appropriate to identify sub-groups for whom such therapy is justified.

Acyclovir↗
PubMed1994

Interleukin-1 inhibits sodium and water transport in rabbit cortical collecting duct.

Interleukin-1 (IL-1) induces natriuresis and diuresis. In the present study, the effect of basolateral IL-1 on sodium and water transport was examined in the cortical collecting duct (CCD) perfused in vitro. IL-1, 10 pg/ml and 10 ng/ml, inhibited lumen-to-bath sodium flux (JNa, peq.min-1.mm tubule-1), depolarizing transepithelial voltage (Vt) in a time- and dose-dependent manner. The inhibitory effect of 10 ng/ml but not 10 pg/ml IL-1 on Vt and JNa was mitigated by 5 microM indomethacin (IND) in bath. Also, 10 ng/ml IL-1, which did not affect the basal hydraulic conductivity (Lp, x10(-7) cm.atm-1.s-1) by itself, inhibited the hydrosmotic effect of 20 pM basolateral arginine vasopressin, and 5 microM IND abolished this inhibitory effect of 10 ng/ml IL-1. The present study demonstrated direct inhibitory effect of basolateral IL-1 on sodium and water reabsorption in the rabbit CCD. The effect of IL-1 is suggested to be mediated, in part, by a cyclooxygenase metabolite(s).

Animals↗
PubMed1994

Enhanced volume-sensitive K flux in patients on chronic hemodialysis.

Swelling-activated K flux was investigated in erythrocytes from patients on regular hemodialysis. K influx, measured by 86Rb uptake, was increased in hemodialysis patients from 25.5 +/- 0.6 to 47.3 +/- 3.4 nmol/10(9) cells/h (n = 4, p < 0.01), when the medium osmolarity of Hepes buffer was decreased by 100 mosm/kg H2O. In normal subjects, K influx was also stimulated from 28.1 +/- 1.2 to 37.8 +/- 2.1 nmol/10(9) cells/h (n = 4, p < 0.01). The swelling-activated increment of K influx was comparatively higher in hemodialysis patients (85.5 vs. 34.5% in controls). Reduction of the medium osmolarity by 100 mosm/kg H2O also caused a larger increase of K efflux in hemodialysis patients than in control subjects (171.1 vs. 118.1%). K efflux was increased even in the presence of 10(-4) M ouabain (from 284 +/- 25 to 879 +/- 122 nmol/10(9) cells/h), although the increment of K efflux was completely abolished when Cl was replaced by gluconate (555 +/- 47 nmol/10(9) cells/h with Cl and 467 +/- 44 nmol/10(9) cells/h without Cl). These data suggest that in hemodialysis patients, swelling-activated K transport is enhanced via activation of the Cl-dependent ouabain-insensitive K transport pathway.

Adult↗
PubMed1994

Short-term effects of uninephrectomy on electrical properties of the cortical collecting duct from rabbit remnant kidneys.

Microelectrode techniques were used to assess the electrical properties of the collecting duct cell in the isolated perfused cortical collecting duct from remnant kidneys 3, 6, and 24 h after uninephrectomy (UNX); results were compared with those from sham-operated kidneys. Plasma aldosterone levels did not change during the time course after UNX. The lumen-negative transepithelial voltage was elevated significantly 3 h after UNX, and was increased further 24 h after UNX. The basolateral membrane voltage (VB) was elevated 6 h after UNX, and then was increased further at 24 h. Although the tight junction conductance and the fractional apical membrane resistance (fRA) were not altered at any time points after UNX, the apical membrane conductance as well as the transepithelial (GT) and basolateral membrane conductances increased 6 and 24 h after UNX. The changes in apical membrane voltage, GT, and fRA upon addition of luminal amiloride increased just 3 h after UNX, and then remained elevated at 6 and 24 h. The changes in apical membrane voltage and GT upon addition of luminal Ba2+, the changes in VB upon addition of bath ouabain, and the changes in VB, GT, and fRA upon raising bath K+ were not influenced 3 h after UNX, but increased at 6 and 24 h. At these latter periods after UNX, the transference number of Cl- of the basolateral membrane decreased significantly, whereas the transference number of K+ of the basolateral membrane increased significantly. Simultaneously, addition of Ba2+ to the bath caused the VB to hyperpolarize in parallel with decreases in GT and fRA. We conclude: (a) the initial effect of UNX (3 h) in the collecting duct cell is an increase in apical membrane Na+ conductance; (b) the delayed effects of UNX (6 and 24 h) are increases in apical membrane K+ conductance as well as basolateral membrane Na(+)-K+ pump activity and K+ conductance; (c) the hyperpolarization of VB at 6 and 24 h after UNX may result in the decrease of the ratio of the relative Cl- conductance to the relative K+ conductance of the basolateral membrane and also may increase passive K+ entry into the cell across the basolateral membrane; (d) these time-dependent electrical changes occur independently of plasma aldosterone levels.

Aldosterone↗
PubMed1994

Electrical properties of the rabbit cortical collecting duct from obstructed kidneys after unilateral ureteral obstruction. Effects of renal decapsulation.

Ureteral obstruction causes impaired salt wastage and K+ secretion in the distal nephron segments, including the cortical collecting duct (CCD). Recently, we demonstrated that conductances of Na+ and K+ in the apical membrane, as well as the electrogenic Na(+)-K+ pump activity and the relative K+ conductance in the basolateral membrane of the collecting duct cell, were inhibited in the obstructed kidney after unilateral ureteral obstruction (UUO). To examine whether the increased intrarenal pressure might be causally related to these abnormalities in the CCD, the effects of unilateral renal decapsulation, a maneuver that partially blocks the increase in renal pressure, were evaluated with microelectrode techniques in isolated CCDs from UUO and sham-operated (control) rabbits 24 h after operation. Renal decapsulation had no effects on barrier voltages and conductances in the CCD from control animals. The lumen-negative transepithelial (VT) and basolateral membrane (VB) voltages as well as the transepithelial (GT) and the apical membrane (GA) conductances were decreased in the CCD from UUO animals compared with control animals. Pretreatment of renal decapsulation partially corrected the decreases in VT, VB, GT, and GA seen in the CCD from UUO animals. The changes in apical membrane voltage and GT upon addition of luminal amiloride and Ba2+, and the changes in VB upon addition of bath ouabain, were also decreased in the CCD from UUO animals compared with control animals. Pretreatment of renal decapsulation also partially corrected the above abnormalities seen in UUO animals, whereas it had no effect in control animals. The transference numbers for Cl- (tCl) and K+ (tK) in the basolateral membrane were, respectively, increased and decreased in the CCD from UUO animals compared with control animals. Pretreatment of renal decapsulation also partially corrected the changes in tCl and tK seen in UUO animals, whereas it had no effect in control animals. We conclude that, in UUO animals, renal decapsulation partially corrects the inhibition of apical Na+ and K+ conductances as well as basolateral Na(+)-K+ pump activity and relative K+ conductance seen after UUO, whereas in control animals it has no effect. The increased renal pressure may partly contribute to the defects in Na+ and K+ transport in the CCD from obstructed kidneys. Renal decapsulation has protective effects on impaired Na+ and K+ transports in the CCD after ureteral obstruction.

Animals↗
PubMed1994

Differential susceptibility of morphologically TPA-resistant and -sensitive Balb/c 3T3 variants to TPA-induced cell transformation: relationship to induction of membrane ruffling.

To investigate the responsiveness to phorbol ester-mediated malignant cell transformation of Balb/c 3T3 variant clones that were morphologically phorbol ester-sensitive and -resistant, we used an in vitro two-stage transformation assay in which cells were treated with 0.1 microgram/ml of MCA as an initiator and subsequently with 12-O-tetradecanoylphorbol-13-acetate (TPA) as a promoter. The morphologically TPA-sensitive variant, TR5, and the parent cells showed a relatively low sensitivity to TPA-induced cell transformation, whereas the morphologically TPA-resistant variant, TR4 cells, exhibited 50- to 100-fold higher sensitivity to phorbol ester-induced cell transformation than the parent or the TR5 cells. We investigated the effects of TPA on protein kinase C activity, 80 kDa PKC substrate phosphorylation, the organization of actin stress fibers, DNA synthesis, and anchorage-independent growth in the three cell clones. They showed similar responses to these biological and biochemical events, indicating that these PKC-mediated events may not be the causes of the differential responsiveness of the variant cells to TPA-induced cell transformation. We further examined their responsiveness to growth factor-mediated and spontaneous induction of membrane ruffling. When these cells were stimulated by PDGF in their growing phase, membrane ruffling was rapidly induced in the three cells. However, the PDGF-mediated membrane ruffling was completely suppressed in parent and TR5 but not TR4 cells in the confluent, contact-inhibited (steady-state) growth phase. Similar responses were observed by other growth factors such as insulin, IGF-I, acidic or basic FGF. In addition, when the cells were cultured beyond confluence in the presence of TPA, spontaneous membrane ruffling was induced continuously up to termination of culture in TR4 but not in parent and TR5 cells. These results suggest that the deficiency in cell contact-mediated inhibition of membrane ruffling may be responsible for hypersensitivity of TR4 cells to TPA-induced cell transformation.

3T3 Cells↗
PubMed1994

Induction of membrane ruffling by growth factors in morphologically TPA-resistant Balb/c3T3 TR4 cells.

To investigate the biological characteristics of a Balb/c3T3 variant TR4 clone which is morphologically resistant to TPA and hypersensitive to v-src induced metastasis, we compared the responsiveness of the variant and its parent cells to growth factor-induced membrane ruffling. When the confluent cells were stimulated with PDGF, membrane ruffling was rapidly induced in TR4 but not in the parent cell cultures. In TR4 cells, membrane ruffling was observed under a phase-contrast microscope within 2 min after the addition of PDGF, reaching the maximum 5 min later and thereafter decreased gradually to the control level. There were no apparent differences in 125I-PDGF binding kinetics between TR4 and parent cells. Similar membrane ruffling was induced by other growth factors such as insulin, IGF-I, acidic or basic FGF but not by EGF or alpha- and beta-TGF, only in TR4 cells. When TR4 cells were incubated with TPA just before stimulation with these growth factors, growth factor-induced membrane ruffling was completely inhibited. Also, 5 out of 6 clones of stable fusion cells between TR4 and parent cells showed the parental type of responses to TPA and growth factors, indicating that the TR4 phenotype is recessive. These results suggest that the variant TR4 cells may acquire the genetic and recessive alteration of a cellular factor which is responsible for the regulation of growth factor-mediated membrane ruffling and that this genetic alteration occurs at a common step downstream of growth factor-mediated cascades, rather than at their receptor level.

3T3 Cells↗
PubMed1994

Sex-associated differences in protein 1 values in urine: immunochemical detection of protein 1 in genital tissues.

Immunochemical methods were used to analyse sex-associated differences in urinary protein 1 concentration. Spot urine from seven normal men and seven women of reproductive age was collected in four sequentially divided fractions, and protein 1 concentration in each fraction was measured by an enzyme immunoassay using the sandwich method: protein 1 values in the first of the sequential urine samples from the male subjects were remarkably high (81.4 +/- 80.4 micrograms/l; mean +/- 1 SD), but were much lower in the remaining three fractions. In females, on the other hand, protein 1 values were low (0.7 +/- 0.4 microgram/l), were uniform in all four sequential fractions, and were close to those of the last three fractions of urine from male subjects. Based on this finding, protein 1 concentration was measured in 14 specimens of seminal plasma, where concentration of protein 1 was high (1259.1 +/- 1716.5 micrograms/l; range, 201.9 to 6580.0 micrograms/l). On Western blotting, protein 1 in seminal plasma had a molecular mass of M(r) 14,000, the same as that of protein 1 purified from the urine of patients with chronic renal failure of probable plasma origin, and of concentrated male urine collected at the initiation of voiding, which is thus thought to come mainly from genital tissue. Protein 1 was found to be in high concentration (434.8 +/- 504.6 micrograms/l) in five aspirated fluids collected at the ejaculatory duct after squeezing the prostate. Three prostate tissue extracts contained protein 1 concentrations ranging from 8.6 to 50.1 micrograms/l. Protein 1 is also present in seminal vesicle fluids (7.1 +/- 2.8 micrograms/l; range, 2.3 to 9.5 micrograms/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Improvement of poor operant performance by continual intake of phenobarbital in spontaneously epileptic rats.

Spontaneously epileptic rats (SER) are a double mutant (zi/zi, tm/tm) obtained by mating the tremor rats with another tremulous mutant, zitter rats, and spontaneously exhibit absence-like seizures, tonic convulsions and wild jumping or running episodes. In addition, SER exhibit retardation in learning ability under differential reinforcement at a low rate (DRL)-5 sec schedule of food reinforcement in operant behavior at 14 to 15 weeks of age. We examined the long-term effects of phenobarbital (PB) on total bar presses, reinforcements and inter-response time distribution to assess whether the poorness of learning ability in SER can be ascribed to frequent occurrence of seizures. Food pellets containing 0.1% PB were given ad libitum to male SER from 7 weeks, and operant behavior was examined at 13 to 14 weeks of age. Tonic seizures and wild jumping or running episode were inhibited effectively and poor operant performance was significantly improved by continual intake of PB in SER.

Administration, Oral↗
PubMed1994

Varied value of urinary N-acetyl-beta-D-glucosaminidase isoenzyme B in males of reproductive age.

A reliable enzyme-linked immunosorbent assay designed to detect N-acetyl-beta-D-glucosaminidase isoenzyme B (NAG-B) was used to determine distribution and variation of urinary NAG-B in normal and pathologic urine. NAG-B values varied over a much broader range in urine from male than in that from female subjects under different conditions of sampling. Because NAG-B values are markedly high in the semen (5800.2 micrograms/liter on the average), contamination of the urine with NAG-B from genital tissues occurs at urination, when it enters urine containing NAG-B of renal origin. The clinical significance of NAG-B and total NAG enzymatic activity as a renal tubular marker should be carefully evaluated when analyzing urine of males from reproductive age.

Acetylglucosaminidase↗
PubMed1994

Bone marrow transplant recipients harbor the B variant of human herpesvirus 6.

Lymphotropic herpesviruses have recently been isolated from patients undergoing kidney, liver and bone marrow transplantation (BMT). We have molecularly characterized isolates of HHV-6 from children undergoing allogenic BMT. We show that viruses recovered from the BMT recipients correspond to the B variant of human herpesvirus 6, the etiological agent of exanthem subitum. HHV-6 B strains are known to be associated with infections in the majority of children in infancy or early childhood. Infection in the BMT recipients most likely reflects the reactivation of these viruses during immunosuppressive treatment. Each of the reactivated viruses has its own characteristic heterogeneous (het) sequence. We show that the het sequence is stably unique for each HHV-6 strain. We also show that prolonged viremia can be documented with some of the patients, unlike the characteristic short duration febrile sickness in the exanthem subitum cases of infancy. The mechanism of HHV-6 B reactivation from latency is not known. Furthermore, the full clinical outcome of HHV-6 B viremia in the BMT patients requires further investigation.

Adolescent↗
PubMed1994

[Modified CHOP and radiation therapy in an aged patient with angioendothelial lymphoma].

A 77-year-old man was admitted because of high fever and general malaise. Whole-body CT showed large bilateral adrenal masses and para-aortic lymphadenopathy. Needle biopsy of the adrenal mass revealed mononuclear tumor cells within the lumens of small vessels, indicating the features of angioendothelial lymphoma. Immunohistochemically, these tumor cells were B cell lineage (positive for LCA, Mx-pan B, MB-1, and negative for factor VIII-related antigen, UEA-1, QB/ENDO 10). We used a modified CHOP therapy (500 mg of cyclophosphamide, 40mg of 4'-o-tetrahydropyranyl doxorubicin, 2mg of vindesine, and 50 mg of prednisolone) due to the patient's advanced age and general condition. Following the first course of this modified CHOP, the adrenal masses and para-aortic lymph nodes decreased dramatically in size, and his subjective symptoms also improved remarkably. Following three courses of modified CHOP, the patient developed dementia and disturbance of consciousness. Brain MRI revealed enhanced multiple nodular lesions. A diagnosis of multiple brain metastasis was made and modified CHOP and radiation therapy were begun, which relieved his symptoms for some time. However, he later died of pneumonia with severe leukopenia. A postmortem examination was performed. Microscopic examination showed no residual tumor cells in the adrenal gland. brain lymph nodes, or other organs. These results suggest that modified CHOP and radiation therapy may have beneficial anti-tumor effects against angioendothelial lymphoma.

Adrenal Gland Neoplasms↗