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Biomedical subjects

H Mogami

Publications and source records attributed to H Mogami.

At least 19 recordsLinked to original sources
PubMed1995

Expression of calcium-permeable cation channel CD20 accelerates progression through the G1 phase in Balb/c 3T3 cells.

CD20 is a transmembrane protein that functions as a Ca(2+)-permeable cation channel (Bubien, J. K., Zhou, L. J., Bell, P. D., Frizzel, R. A., and Tedder, T. F. (1993) J. Cell Biol. 121, 1121-1132) and is involved in growth regulation of B lymphocytes. In order to further investigate the role of calcium entry in cell cycle progression, we introduced the cDNA encoding a Ca(2+)-permeable cation channel, CD20, into Balb/c 3T3 cells. Balb/c 3T3 cells transfected with a vector containing cDNA encoding CD20 expressed the CD20 protein, which was detected by assaying the binding of a monoclonal antibody against CD20. Calcium-permeable cation channel activity was detected in CD20-expressing cells by whole cell patch clamp recording and microfluorometric determination of the cytoplasmic Ca2+ concentration using fura-2. The expression of CD20 induced significant alterations in the responses of the cells to insulin-like growth factor-I (IGF-I). IGF-I induced DNA synthesis by control cells only when they had been pretreated with both platelet-derived growth factor (PDGF) and epidermal growth factor (EGF). In contrast, DNA synthesis by 30% of the quiescent CD20-expressing cells was initiated in response to IGF-I in the absence of priming with PDGF and EGF. When control quiescent cells were primed with PDGF and EGF, the addition of IGF-I led to the initiation of DNA synthesis after 14 h or more, whereas it induced DNA synthesis by CD20-expressing cells primed with PDGF and EGF 4 h earlier. The IGF-induced DNA synthesis was dependent on extracellular Ca2+, and expression of CD20 reduced the concentration of extracellular Ca2+ required for it. Furthermore, DNA synthesis by approximately 25% of the CD20-expressing cells was initiated after priming with PDGF and EGF, even in the absence of the progression factor IGF-I. These results indicate that CD20 expressed in Balb/c 3T3 cells functions as a constitutively active Ca(2+)-permeable cation channel and that expression of CD20 accelerates G1 progression in a Ca(2+)-dependent manner.

3T3 Cells↗
PubMed1995

Production of activin A and follistatin in cultured rat vascular smooth muscle cells.

Activin A, a member of the transforming growth factor beta supergene family, modulates DNA synthesis in cultured rat vascular smooth muscle cells (VSMC) (Kopma et al. (1993) Exp. Cell. Res. 206, 152-156). In the present study, we studied the production of activin A and follistatin in VSMC. When VSMCs cultured in a 24-well plate were cultured with 10% fetal calf serum (FCS) for 24 h, 0.94 +/- 0.20 pmol/well (mean +/- SE, n = 6) of bioactive activin was released into the culture media. Reverse-transcription polymerase chain-reaction revealed the expression of mRNA for the beta A subunit of inhibin but not for either the beta B or alpha subunit. Bioactivity of activin was increased in quiescent cells treated with FCS or platelet-derived growth factor (PDGF) but not with angiotensin II (Ang II) or insulin-like growth factor-I (IGF-I). Ang II or IGF-I did not stimulate DNA synthesis by itself but, when these two agents were combined, they increased nuclear labeling by 16.4% and release of bioactive activin by 170% of basal. The dose-response relationship and time course study indicated that PDGF-mediated release of activin correlated with initiation of DNA synthesis. Steady state expression of mRNA for the beta A subunit was markedly elevated 12 h after the addition of PDGF and was reduced thereafter. To assess the significance of autocrine activin, the effect of PDGF was determined in the presence and absence of excess of exogenous follistatin. The PDGF-mediated DNA synthesis was enhanced by the addition of excess follistatin.(ABSTRACT TRUNCATED AT 250 WORDS)

Activins↗
PubMed1995

Conversion of amylase-secreting rat pancreatic AR42J cells to neuronlike cells by activin A.

When AR42J cells, an amylase-secreting pancreatic exocrine cell line, were treated with activin A, cells extended neuritelike processes, and, concomitantly, amylase-containing vesicles disappeared. Immunofluorescence and immunoelectron microscopy revealed that these processes had neurite-specific cytoskeletal architectures: neurofilaments and microtubule bundles with cross-bridges of microtubule-associated protein 2. In addition to such morphological changes, activin-treated cells exhibited a marked increase in cytoplasmic free calcium concentration in response to depolarizing concentration of potassium. Moreover, activin-treated AR42J cells expressed mRNA for alpha 1 subunit of the neuroendocrine/beta cell-type voltage-dependent calcium channel. In naive AR42J cells, a sulfonylurea compound, tolbutamide, did not affect free calcium concentration, while it induced a marked elevation of free calcium in activin-treated cells. Single channel recording of the membrane patch revealed the existence of ATP-sensitive potassium channel in activin-treated cells. These results indicate that activin A converts amylase-secreting AR42J cells to neuronlike cells. Given that pancreatic endocrine cells possess neuronlike properties and express ATP-sensitive potassium channel as well as neuroendocrine/beta cell-type voltage-dependent calcium channel, activin treatment of AR42J cells may provide an in vitro model system to study the conversion of pancreatic exocrine cells to endocrine cells in islets.

Activins↗
PubMed1995

Modulation of adenosine triphosphate-sensitive potassium channel and voltage-dependent calcium channel by activin A in HIT-T15 cells.

The ATP-sensitive potassium channel (KATP channel) determines the membrane potential of pancreatic beta-cells and plays a critical role in the regulation of insulin secretion. The present study was conducted to investigate the effect of activin A, a member of the transforming growth factor-beta supergene family, on the KATP channel in HIT-T15 clonal hamster insulinoma cells. In an excised inside-out patch, ATP-sensitive currents with a single channel conductance of approximately 20 picosiemens were observed. In an outside-out patch, currents with identical unitary conductance were also observed. In either case, the currents were augmented by diazoxide and blocked by glibenclamide, verifying that they were KATP channel currents. When KATP channel currents were monitored in an outside-out patch, activin A added to the bath solution inhibited KATP channel currents. Upon removal of activin A, the KATP channel currents were restored, suggesting that the inhibition was not due simply to spontaneous disappearance of channel activity (run-down). The KATP channel activity was markedly reduced after the addition of activin A and was reversed by diazoxide. Besides the inhibition of KATP channel, activin A increased, in a perforated patch, the amplitude of the inward Ba2+ current in response to a depolarizing pulse from -40 to +10 mV. Under the current clamp condition, activin A induced gradual depolarization, followed by a burst of action potentials. Activin-mediated action potentials were accompanied by an elevation of the cytoplasmic free calcium concentration. These results indicate that activin A causes depolarization of the plasma membrane by inhibiting the activity of the KATP channel. In addition, activin A directly modulates the voltage-dependent calcium channel and augments calcium entry.

Action Potentials↗
PubMed1994

Inhibition of ATP-sensitive K+ channel by a non-sulfonylurea compound KAD-1229 in a pancreatic beta-cell line, MIN 6 cell.

We studied the mechanism of action of KAD-1229, a non-sulfonylurea compound shown to stimulate insulin secretion, in a glucose responsive insulinoma cell line, MIN 6 cells. In microsomal fraction of MIN 6 cells, KAD-1229 displaced binding of [3H]glibenclamide in a concentration-dependent manner. The dissociation constant and the maximum binding capacity were 0.61 nM and 8.70 pmol/mg.protein, respectively. In inside out configuration of patch-clamp technique, KAD-1229 attenuated the opening of ATP-sensitive K+ channels. The effect of KAD-1229 was detected at 10(-8) M, and 10(-5) M KAD-1229 almost completely blocked the activity of ATP-sensitive K+ channel. When membrane potential was monitored by a perforated mode of patch clamp, KAD-1229 induced depolarization of plasma membrane, which was followed by a burst of action potentials. These action potentials were blocked by cobalt. In a fura-2-loaded single MIN 6 cell, KAD evoked an elevation of intracellular free Ca2+ concentration, [Ca2+]i. The KAD-1229-mediated elevation of [Ca2+]i was attenuated by either removal of extracellular Ca2+ or an addition of nifedipine. Finally, KAD-1229 augmented insulin secretion in MIN 6 cells in a concentration-dependent manner. KAD-1229 also enhanced the effect of glucose and nifedipine inhibited the action of KAD-1229 on insulin secretion. These results indicate that KAD-1229 stimulates insulin secretion by stimulating Ca2+ influx and that, despite the lack of sulfonylurea structure, KAD-1229 binds to sulfonylurea receptors and inhibits the activity of ATP-sensitive K+ channel in MIN 6 cells.

Action Potentials↗
PubMed1992

[Intraarterial urokinase infusion therapy with superselective catheterization for acute occlusive cerebrovascular disease].

Intraarterial urokinase infusion therapy with superselective catheterization was performed on 11 patients for acute occlusive cerebrovascular disease. The subjects were five men and six women with a mean age of 70 years (range, 48-83 years). Nine of 11 patients had middle cerebral artery occlusion and two had basilar artery occlusion. The interval from onset to infusion ranged from 3.5 to 9 hours, and the total dosage of urokinase from 24 x 10(4) to 150 x 10(4) IU. Recanalization of the occluded artery was achieved in nine patients (82%), and favorable clinical outcome was achieved in seven patients (64%). Six of whom were discharged with no neurologic deficits. Hemorrhagic infarction occurred in two patients without clinical deterioration. Our observations suggest that intraarterial urokinase infusion therapy with superselective catheterization may be very useful in the acute stage of occlusive cerebrovascular disease.

Acute Disease↗
PubMed1992

[A case with delayed-onset radiation pneumonitis suspected to be induced by oral etoposide].

Radiation pneumonitis usually occurs within 1-3 months after the completion of radiation therapy. A 63-year-old male with primary lung cancer treated by radiation therapy developed radiation pneumonitis 5 months after the completion of radiation therapy. He received 60 Gy to the lung tumor in a conventional fractionation schedule, and then two courses of intravenous chemotherapy using cis-diamine-dichloroplatinum (II) (110-140 mg) and etoposide (140-175 mg). Oral etoposide was initiated for bone metastases on the 104th day after the completion of radiation therapy at a daily dose of 20 mg, to a total dose of 1075 mg. He complained of fever and exertional dyspnea 5 months after the completion of radiation therapy. Chest radiography showed homogeneous infiltrates in the irradiated lung. These clinical signs and symptoms were refractory to antibiotic therapy, but steroid therapy resulted in marked improvement. The development of radiation pneumonitis was suspected to be induced by oral etoposide, which was given before the onset of radiation pneumonitis. These data suggest that etoposide induces a recall phenomenon, as has been demonstrated with such drugs as adriamycin and actinomycin-D.

Administration, Oral↗
PubMed1992

[Temperature distribution and geometry of the electrodes in RF interstitial hyperthermia using circular and interstitial electrodes].

To evaluate the feasibility of clinical application of a newly developed interstitial hyperthermia system, which consists of an 8 MHz radiofrequency generator, interstitial needle electrodes, and a superficial circular electrode, we conducted preclinical experiments using an agar phantom and VX-2 carcinoma in the rabbit. In the experiment with an agar phantom, four 4 cm needle electrodes were placed in a square array at intervals of 1.0, 1.5, and 2.0 cm. Thermography demonstrated homogeneous temperature distribution at electrode intervals of 1.0 and 1.5 cm, but hot spots around the electrodes at an interval of 2.0 cm. When electrode deviation was less than 8 degrees from the parallel plane, no temperature deviation was observed. Using two 2 cm electrodes and two 4 cm electrodes in square array, thermography demonstrated a homogeneous temperature distribution in the area surrounded by the electrodes. Even if the electrodes were located at the periphery of the agar phantom, a homogeneous temperature distribution was obtained in the area surrounded by the electrodes. Using four 4 cm electrodes at intervals of 1.5 cm in VX-2 carcinoma in the rabbit, ideal heating was obtained: 42 degrees C at the periphery of the tumor and 43 degrees C at the center. These data suggest that the newly developed interstitial hyperthermia apparatus provides homogeneous heat distribution at electrode intervals of 1.5 cm or less and can be used in a Phase I study for deep-seated or superficial tumors.

Animals↗
PubMed1992

[Results of radiation therapy for squamous cell carcinoma of the uterine cervix using high dose-rate intracavitary irradiation].

We retrospectively analyzed 216 previously untreated patients with cervical cancer treated by high dose-rate intracavitary irradiation between 1978 and 1986. Cumulative 5-year survivals in stage Ib, IIa, IIb, IIIa, IIIb and IVa were 72.3%, 88.9%, 68.9%, 75.0%, 64.0% and 16.7%, respectively. Cause-specific 5-year survivals in stage Ib, IIa, IIb, IIIa, IIIb and IVa were 93.3%, 88.9%, 74.7%, 75.0%, 68.9%, and 18.8%, respectively. Recurrences outside the pelvis in stage IIb and IIIb (14.9% and 24.0%) were more common than loco-regional recurrences (10.3% and 12.0%). However, loco-regional recurrences (50%) were most frequent in stage IVa. Thirteen patients (6.0%) required surgical management for intestinal complications (severe). Six patients (2.7%) died due to intestinal complications (fatal). These fatal and severe complications were closely correlated with the dose of external radiation. These data suggest that intracavitary irradiation using a high dose-rate system is useful for the treatment of uterine cancer; however, further efforts to reduce intestinal complications by lowering the dose of external radiation will be necessary. It is also suggested that a combined modality, such as chemotherapy, is necessary for controlling metastases outside the pelvis in stage IIb and IIIb, and for local control in stage IVa.

Adult↗
PubMed1992

Oscillation of cytoplasmic free calcium concentration induced by insulin-like growth factor I.

The effect of insulin-like growth factor I (IGF-I) on cytoplasmic free calcium concentration ([Ca2+]c) was studied in single BALB/c 3T3 cells by monitoring fura-2 fluorescence. In primed competent cells, IGF-I (1 nM) increased [Ca2+]c in approximately 60% of the cells tested. IGF-I-mediated elevation of [Ca2+]c was observed after a 4- to 17-min lag period. Elevation of [Ca2+]c was only transient but was followed by repetitive increases in [Ca2+]c. The interval between each peak was quite constant in each cell at a given concentration of IGF-I. When the concentration of IGF-I was reduced, both the latent period and interval of each peak were prolonged, whereas amplitude of the increase in [Ca2+]c was not altered. In medium containing 10 microM extracellular calcium, IGF-I did not cause any increase in [Ca2+]c. Likewise, blockade of IGF-induced calcium entry by either cobalt or tetramethrin abolished IGF-I action on [Ca2+]c. IGF-I-mediated oscillation was not affected by either ryanodine or caffeine, compounds that affect calcium-induced calcium release. In addition, pretreatment of the cell with neomycin did not affect IGF-I-mediated oscillation. In agreement with this, IGF-I did not augment production of [3H]inositol trisphosphate in cells prelabeled with [3H]inositol. These results indicate that IGF-I induces oscillation of [Ca2+]c in a single primed competent cell and that the oscillation is totally dependent on IGF-I-mediated calcium entry.

3T3 Cells↗
PubMed1991

[Embolotherapy of varicocele by stainless steel coil].

Fifty-two patients with varicocele underwent embolotherapy using stainless steel coils. Forty-six of the patients complained of infertility, four of scrotal mass and two of scrotal pain. The procedure was successful in 42 of the 52 patients (81%). Positive semen analyses increased 53% (16/30), and the number of subsequent pregnancies was five of 33 (15%). We conclude that embolotherapy with the coils is a useful therapeutic procedure for varicoceles.

Adolescent↗
PubMed1991

Chemotherapy of brain metastases from lung carcinoma: a controlled randomized study.

A controlled randomized study was carried out to evaluate the effects of chemotherapy in patients with brain metastases from lung carcinoma. One hundred patients were randomly divided into three groups at the time of diagnosis or after surgery for metastases. Group A received radiotherapy alone; Group B received radiotherapy and chloroethylnitrosoureas (methyl-CCNU, 100-120 mg/m2, or ACNU 80-100 mg/m2, every 6-8 weeks), and Group C received radiotherapy and a combination of chloroethylnitrosoureas and tegafur (300 mg/m2, daily). Of the 100 patients, 88 could be evaluated. The reduction rates of the tumors of the patients in whom tumor was not surgically removed or not totally removed were compared. Complete resolution of the tumor was noted in 29, 69, and 63% of the patients in Groups A, B, and C, respectively. Tumor regression of greater than or equal to 50% was seen in 36, 69, and 74% of the patients in Groups A, B, and C, respectively. The difference in the response rates of Groups A and C was statistically significant (P less than 0.05). Median survival after the start of treatment for brain metastasis was 27, 30.5, and 29 weeks in Groups A, B and C, respectively. There was 1 long-term survivor (more than 5 years) in Group A, 3 in Group B, and 1 in Group C. The main cause of death was deterioration attributable to the primary lesion or systemic metastasis, and no statistical difference was noted in survival time among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1991

Purine catabolites in cerebral interstitial fluid during progression of and recovery from ischemia.

The concentrations of purine catabolites in the cerebral interstitial fluid during progression of and recovery from ischemia were studied using brain microdialysis and high-performance liquid chromatography. Sealed 0.5-mm hollow dialysis fibers were stereotactically implanted into either the cerebral cortex or hippocampus of ketamine anesthetized gerbils and perfused with artificial cerebrospinal fluid at 2 microliters/min. Cerebral ischemia was induced by occlusion of the bilateral common carotid arteries. The reflectance spectra of oxy- and deoxyhemoglobin at the brain surface were monitored over the scalp to assess ischemia and confirm recirculation. Ischemia caused a rapid, 4.8-fold increase in the extracellular concentration of adenosine. The progressive increase in the concentration of adenosine, inosine, and hypoxanthine soon after recirculation is particularly interesting. The subsequent decrease in purine compound concentration was rapid for adenosine but more gradual for inosine and hypoxanthine. Calculated K values for adenosine deaminase and purine nucleoside phosphorylase were 0.045/min and 0.016/min, respectively. However, no xanthine, uric acid, or purine nucleotides were found in the perfusate. These observations indicated the presence of purine catabolites in the cerebral interstitial space as well as consecutive degradation and recycling involving the interconversion of purine compounds by biochemical metabolic pathways.

Animals↗
PubMed1991

A frameless, armless navigational system for computer-assisted neurosurgery. Technical note.

A computer-assisted neurosurgical navigational system has been developed which displays intraoperative manipulation on the preoperative computerized tomography (CT) scans or magnetic resonance (MR) images. The system consists of a three-dimensional digitizer, a personal computer, and an image-processing unit. Utilizing recently developed magnetic field modulation technology, the three-dimensional digitizer determines the spatial position and orientation angles of the resin probe, triangle-shaped pointer, or suction tube with a small attached magnetic field sensor. Four fiducial markers on the scalp were used to translate the spatial data of the probe onto the preoperative CT scans or MR images of the patient. With this frameless, armless navigational system, CT or MR-imaging stereotaxy can be applied to conventional open neurosurgery without limiting the operative field or interfering with the surgical procedures.

Adult↗
PubMed1991

[Coronary vasospastic activity at sites of percutaneous transluminal coronary angioplasty: evaluation using intracoronary acetylcholine administration].

To investigate coronary vasospastic activity after percutaneous transluminal coronary angioplasty (PTCA), we performed intracoronary injection of acetylcholine in 55 patients, mean 3.3 months after successful PTCA. Coronary spasm was defined as transient total or subtotal occlusion of the PTCA sites. Sixty-nine lesions of the 55 patients were examined to determine whether spasm was provoked by incremental doses of acetylcholine. Restenosis was defined as coronary luminal narrowing of > or = 50% after nitroglycerin or isosorbide dinitrate. Twenty of the 55 patients (36%) and 23 of the 69 lesions (33%) had coronary spasm. There was no correlation between the incidence of coronary spasm and the interval from PTCA to the acetylcholine test. The spasm was provoked in 17 lesions of the 50 non-restenotic lesions (34%) and was also provoked in 6 of the 19 restenotic lesions (32%). On the other hand, restenoses occurred in 6 of the 23 spastic lesions (26%) and in 13 of the 43 non-spastic lesions (28%). There was no correlation between the incidence of coronary spasm and the occurrence of restenoses. Twenty-four patients had undergone acetylcholine provocative test before PTCA. Among these 24 patients, 11 had coronary spasm before PTCA, and 7 had coronary spasticity after PTCA. Four patients who had positive evidence of coronary spasm before PTCA did not show negative spasm after PTCA. On the other hand, 3 patients who did not show evidence of coronary spasm showed positive evidence of coronary spasm after PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1991

[A case of Osler-Weber-Rendu disease with brain abscess; the mechanism of the formation of brain abscess and its treatment in Osler-Weber-Rendu disease].

A 54 year-old man, who had a hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease; O-W-R) accompanied by pulmonary arteriovenous fistulas (PAVFs) and congestive heart failure, developed seizure, right hemiparesis and dysphasia. A brain CT scan revealed a cystic lesion with perifocal edema in left frontoparietal lobe. A contrast enhanced CT scan showed a ring-like enhancement. Dynamic CT scans disclosed that the ring in the cortical side was enhanced more thickly than that in the ventricular side. Considering the severity of the cardio-pulmonary condition, and the deep location of the abscess, we performed an echo-guided aspiration and drainage of the abscess under local anesthesia. No bacteria were demonstrated in the culture of the contents of the abscess. After the surgery, the right hemiparesis and dysphasia were much improved and a CT scan showed the marked reduction of the abscess. However, around eight days after the surgery, the patient showed severe pleural effusion due to progressive heart failure and died on the 11th postoperative day. Autopsy disclosed a shrunken brain abscess, multiple cerebral infarction, multiple PAVFs and severe constrictive pericarditis which was regarded as the cause of death in the patient. In this report, we presented the therapeutic advantage of echo-guided surgery for the treatment of brain abscess in a high-risk patient. We also discussed the mechanism of the formation of brain abscess in patients of O-W-R disease by reviewing published cases.

Arteriovenous Fistula↗