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Biomedical subjects

T Kuga

Publications and source records attributed to T Kuga.

At least 19 recordsLinked to original sources
PubMed1998

Concentrations of thrombopoietin in bone marrow in normal subjects and in patients with idiopathic thrombocytopenic purpura, aplastic anemia, and essential thrombocythemia correlate with its mRNA expression of bone marrow stromal cells.

The function of bone marrow (BM) stromal thrombopoietin (TPO) in megakaryopoiesis remains unknown. In the present study we attempted to clarify the pathophysiological implications of stromal TPO in normal subjects (NS) and in patients with idiopathic thrombocytopenic purpura (ITP), aplastic anemia (AA), and essential thrombocythemia (ET) by measuring TPO concentrations in BM and peripheral blood (PB) and by estimating the levels of stromal TPO mRNA with TaqMan fluorescence-based post-reverse transcription-polymerase chain reaction product detection system. The results showed that TPO concentrations in PB were significantly elevated in patients with ITP (34.9 +/- 11.7 pg/mL) and AA (364.1 +/- 153.5 pg/mL) but within normal range in patients with ET (each 20.0 and 22.1; NS, 22.1 +/- 8.2 pg/mL). In all subjects, the TPO concentrations in BM correlated well with the PB levels, and the former were consistently higher than the latter. The concentrations of TPO in BM also correlated with the levels of TPO mRNA in stromal cells. Furthermore, expression levels of TPO mRNA clearly correlated with megakaryocyte counts in NS and patients with ITP, indicating that stromal TPO actually enhances megakaryopoiesis. Thus, our results in the present study indicate that TPO from BM stromal cells is considered to play an essential role for megakaryopoiesis under various patho-physiological conditions.

Anemia, Aplastic↗
PubMed1998

A proof of glutathione S-transferase-pi-related multidrug resistance by transfer of antisense gene to cancer cells and sense gene to bone marrow stem cell.

In order to directly prove the involvement of GST-pi in drug resistance, it's antisense gene was transduced into human colorectal cancer cell line which has been shown to express high level of GST-pi and the sensitivity of this cell line to anticancer drugs were assessed. The transfectant showed higher sensitivity to adriamycin (3.3-fold), Cisplatnum (2.3-fold), Melphalan (2.2-fold), Etoposode (2.2-fold) than the parental cell, while the sensitivity to vincristine, mitomicin C, 5-fluorouracil was unchanged by transfection. When the transfectant and parental cells were innoculated in nude mice and treated with adriamycin, a significant suppression of tumor growth was observed with the transfectant as compared to the parental cell. On the basis of this observation, we then transduced sense GST-pi gene into human bone marrow stem cells (CD34+ cells) to protect them from toxicity of anticancer drug. The gene transduced CD34+ cells formed more CFU-GM than nontransduced CD34+ cell in the presence of adriamycin (30 ng/ml). Thus, the autotransplantation of GST-pi gene transduced cell into cancer patients to protect the bone marrow from subsequent highdose chemotherapy is considered to be a new strategy for cancer gene therapy.

Animals↗
PubMed1998

Detection of type III collagen fragments in specimens of abdominal aortic aneurysms.

The purpose of this study was to analyze the collagens in aortic aneurysm walls and to investigate the mechanism of the formation of calcified abdominal aortic aneurysms (AAAs). Collagens were extracted from human aneurysmal aortic walls obtained during surgery, and from human nonaneurysmal aortic walls obtained at autopsy, using pepsin-acetic acid digestion. Electrophoresis and immunoblotting were performed. Type III collagen was found to be reduced in the arteriosclerotic aneurysmal aortic walls. The alpha1 chain of type II collagen/alpha1 chain of type I collagen ratio was 0.35+/-0.11 in the aortic aneurysms and 0.68+/-0.11 in the nonaneurysmal aortic walls (P=0.0111). All the calcified aneurysms were associated with type III collagen fragments having molecular mass of approximately 70 kDa and 30 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Thus, we concluded that AAAs with calcification may be caused by an abnormal degradation of type III collagen.

Aortic Aneurysm, Abdominal↗
PubMed1997

Vasculoprotective role of inducible nitric oxide synthase at inflammatory coronary lesions induced by chronic treatment with interleukin-1beta in pigs in vivo.

BACKGROUND: We recently developed a porcine model in which chronic, local treatment with interleukin-1beta (IL-1beta) causes coronary arteriosclerotic changes and hyperconstrictive responses. Inflammatory cytokines are known to induce inducible NO synthase (iNOS) in the vascular smooth muscle. This study was designed to examine whether or not the production of NO by iNOS has a protective or deleterious effect on the coronary artery in vivo. METHODS AND RESULTS: A segment of the porcine coronary artery was aseptically wrapped with cotton mesh absorbing IL-1beta suspension. We inhibited both eNOS and iNOS activity by cotreatment with L-NAME (a nonspecific inhibitor of NOS) and iNOS activity alone by aminoguanidine (a selective inhibitor of iNOS). Immunostaining showed that iNOS was absent in the normal coronary artery, whereas it was highly expressed 1 day after the application of IL-1beta and thereafter downregulated until 14 days. In contrast, eNOS was well maintained throughout the study period. Two weeks after the operation, hyperconstrictive responses to intracoronary serotonin and neointimal formation were noted at the IL-1beta-treated site, and both responses were significantly greater at the site cotreated with either L-NAME or aminoguanidine. CONCLUSIONS: These results indicate that iNOS is transiently induced in vivo in response to local inflammation and that NO produced by iNOS exerts an inhibitory effect against the cytokine-induced proliferative/vasospastic changes of the coronary artery in vivo.

Animals↗
PubMed1997

Fibronectin fragment-facilitated retroviral transfer of the glutathione-S-transferase pi gene into CD34+ cells to protect them against alkylating agents.

To protect bone marrow cells from the toxicity of chemotherapy, a multidrug resistant gene or a dihydrofolate reductase gene has been introduced into stem cells. These genes, however, are not capable of conferring refractoriness to alkylating agents (AA), which are some of the most commonly used agents in chemotherapy regimens. In the present study, an attempt was made to endow human stem cell (CD34+ cells) with resistance to cyclophosphamide, a well-known AA, and adriamycin (ADM) by transducing the glutathione-S-transferase pi (GST-pi) gene whose product is thought to detoxify AA by conjugating them with glutathione and to remove a toxic peroxide formed by ADM. The gene transduction was carried out retrovirally with a virus titer of 1 x 10(5) FFU/ml, employing a recombinant fibronectin fragment; transduction efficiency was extremely low without the fragment. Incubation with interleukin-6 and stem cell factor enhanced the expression of fibronectin ligands VLA4 and VLA5 on CD34+ cells. This enhanced expression of VLA4 and VLA5 was considered to facilitate a close contact of the CD34+ cell to the retroviral vector via fibronectin fragments and the subsequent transduction process. The GST-pi gene-transduced CD34+ cells formed almost 3- and 2.5-fold more CFU-GM than neo gene-transduced CD34+ cells in the presence of 2.5 microg/ml of 4-hydroperoxycyclophosphamide (4-HC), an active form of cyclophosphamide, and 30 ng/ml ADM, respectively. The transfectants formed an appreciable number of colonies, even at higher concentrations of these drugs (5.0 microg/ml of 4-HC, 50 ng/ml of ADM) whereas neo gene-transduced or nontransduced CD34+ cells formed no colonies at all, indicating the possibility of selecting out the transfectants by exposing them to these anticancer drugs. Thus, we were able to demonstrate that transduction of the GST-pi gene confers resistance to cyclophosphamide as well as to ADM, and therefore this approach can be applied clinically for high-dose chemotherapy.

Alkylating Agents↗
PubMed1997

Congenital cystic adenomatoid malformation with extramedullary hematopoiesis of the lung: a case report.

The authors report a case of congenital cystic adenomatoid malformation of the lung (CCAM) with extramedullary hematopoiesis (EMH). A baby girl suffered from Rh incompatibility and hemolytic anemia. She exhibited respiratory distress. Chest radiography and magnetic resonance imaging findings showed a CCAM. A resection of the upper and middle lobes of the right lung was performed. Histological examination showed a CCAM of Stocker's type II with EMH. EMH in the lung is very rare. The authors speculate that the cause of our case originated from Rh incompatibility and development arrest in the CCAM lung.

Cystic Adenomatoid Malformation of Lung, Congenita↗
PubMed1997

Bradykinin-induced vasodilation of human coronary arteries in vivo: role of nitric oxide and angiotensin-converting enzyme.

OBJECTIVES: The present study aimed to determine the role of nitric oxide (NO) and angiotensin-converting enzyme (ACE) in bradykinin (BK)-induced dilation of human coronary arteries in vivo. BACKGROUND: BK, produced by way of the kinin-kallikrein system, causes endothelium-dependent vasodilation. However, little is known about the mechanism of BK-induced dilation of coronary arteries in humans in vivo. METHODS: The effects of an inhibitor of NO synthesis and of an ACE inhibitor on BK-induced coronary vasodilation were examined in 20 patients who had no significant atherosclerotic stenosis in the artery under study. Lumen diameters of the large epicardial coronary arteries and coronary blood flow (CBF) were measured by quantitative coronary arteriography and intracoronary Doppler technique. RESULTS: Intracoronary infusion of BK (0.6 and 2.0 micrograms/min) increased coronary artery diameter and CBF with no change in arterial pressure or heart rate. The BK-induced increases in coronary artery diameter and CBF were significantly reduced (p < 0.01) after pretreatment with NG-monomethyl-L-arginine (200 mumol) and were significantly increased (p < 0.01) after pretreatment with enalaprilat (50 micrograms). CONCLUSIONS: BK-induced dilation of human large epicardial and resistance coronary arteries is mediated by NO and increased by prior ACE inhibition.

Aged↗
PubMed1997

Long-term survival and differentiation of human peripheral blood CD34+ cells in SCID mice.

Human peripheral blood progenitor cells (PBPC) are currently used as a source of hematopoietic reconstitution by autologous transplantation after myeloabrative chemotherapy for malignancies. PBPC would also be useful for allogeneic transplantation since the collection of PBPC is much safer than that of bone marrow stem cells (BM). For allogeneic transplantation, it is imperative to confirm that PBPC contains self-renewable stem cells that can sustain a long lasting hematopoiesis. In the present study, we examined the reconstitution of human hematopoiesis in severe combined immunodeficiency (SCID) mice by transplanting peripheral blood CD34+ cells in which the neo gene was transduced as a marker. In 2 of 4 mice receiving PB-CD34+ cell transplantation, the neo gene appeared as early as 4 weeks and lasted as long as 24 weeks in all DNA preparations of bone marrow, peripheral blood and spleen cells from the SCID mice, while in 2 of 4 mice receiving BM-CD34+ cell transplantation, although the neo gene also lasted as late as 24 weeks, it did not appear as early as in the mice receiving PB-CD34+ cell transplantation. A similar observation was noted in clinical trials, i.e. the white blood cell and platelet recovered earlier by transplantation of PBPC than of BM. In mice who had the neo gene, we were also able to demonstrate by FACS the presence of human lineage specific antigen in the cells as late as 24 weeks after transplantation with PB-CD34+ cells, and the presence of human IgG in the sera 10 weeks after transplantation. These findings indicate that PB-CD34+ cells contain long-term repopulating stem cells which undergo differentiation in SCID mice.

Animals↗
PubMed1997

Role of nitric oxide in substance P-induced vasodilation differs between the coronary and forearm circulation in humans.

It has been shown that substance P causes endothelium-dependent vasodilation in the human coronary and forearm vessels. However, the precise mechanism whereby substance P dilates the coronary and peripheral vasculatures is unknown in humans. The aim of this study was to examine whether the vasodilator effect of substance P is mediated by nitric oxide in the human coronary and forearm vessels. Eight patients with normal coronary angiograms were studied for the measurements of coronary blood flow (intracoronary Doppler guide wire and quantitative coronary arteriography) and forearm blood flow (strain-gauge plethysmograph). Intracoronary acetylcholine (10 micrograms/min for 2 min) and substance P (30 and 90 ng/min for 2 min) increased coronary blood flow from the baseline value. Intracoronary infusion of NG-monomethyl-L-arginine (L-NMMA) at 200 mumol significantly attenuated the magnitudes of increase in coronary blood flow induced by both acetylcholine (p < 0.01) and substance P (p < 0.01). Acetylcholine (4, 8, and 16 micrograms/min for 2 min) and substance P (0.8, 1.6, and 3.2 ng/min for 2 min) also increased forearm blood flow in a dose-dependent manner. Intraarterial L-NMMA (8 mumol/min for 5 min) decreased the magnitudes of increase in forearm blood flow induced by acetylcholine (p < 0.01). L-NMMA at the same dosage decreased the increase in forearm blood flow induced by substance P, but the magnitude of the inhibitory effect of L-NMMA on blood-flow responses to substance P was significantly smaller in the forearm than in coronary vessels. It is suggested that endothelium-derived nitric oxide contributes to substance P-induced vasodilation, and that the contribution of nitric oxide to substance P-induced vasodilation is smaller in the forearm than in coronary circulation.

Acetylcholine↗
PubMed1997

Central role of vascular smooth muscle hyperreactivity in coronary hyperconstriction after balloon injury in miniature pigs.

BACKGROUND: Coronary constrictive responses to autacoids become augmented 1 week after balloon injury in our swine model. The present study aimed to elucidate the mechanisms of this effect. METHODS: In 12 hypercholesterolaemic miniature pigs, the coronary constrictive response to serotonin was examined angiographically 1 week after injury. After the angiographic study, organ chamber experiments using excised coronary artery were performed to clarify whether functional changes in endothelial cells or in vascular smooth muscle cells contributed to the hyperconstriction. RESULTS: The coronary constrictive response to serotonin in vivo was significantly greater at the previously injured site than at the non-injured site. The degree of the hyperconstriction at the previously injured site exceeded that predicted from a geometric theory. Histological examination demonstrated that the previously injured site was almost covered with regenerated endothelial cells. In vitro studies demonstrated that serotonin caused significantly greater contraction in coronary artery strips, whether with or without endothelium, from the previously injured site than in those from the non-injured site. Endothelium-dependent relaxation in response to serotonin was comparable at the injured and non-injured sites. CONCLUSIONS: These results suggest that the coronary hyperconstriction response to serotonin 1 week after injury results primarily from hyperreactivity of vascular smooth muscle. Whereas any contribution of endothelial dysfunction or the geometric effect may be minimal.

Animals↗
PubMed1997

Basal release of nitric oxide is decreased in the coronary circulation in patients with heart failure.

It is unknown whether basal release of endothelium-derived nitric oxide in the coronary artery is altered in heart failure in humans. The aim of the present study was to evaluate the effect of inhibition of nitric oxide synthesis on basal tone of the conduit and resistance coronary arteries in awake patients. Coronary blood flow velocity (Doppler guide wire) and coronary arterial diameter (quantitative coronary angiography) were measured in 14 patients with heart failure caused by nonischemic left ventricular dysfunction (7 idiopathic dilated cardiomyopathy and 7 valvular insufficiency) and 7 patients with normal ventricular function (controls). Intracoronary N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of nitric oxide synthesis, at graded doses decreased coronary blood flow in both groups. However, the magnitude of flow reduction was smaller in patients with heart failure than in control patients (P<.0001). The magnitude of coronary blood flow reduction in response to L-NMMA inversely correlated to indexes of left ventricular contractile function (P<.01) but was not affected by the cause of heart failure. Constriction of the large epicardial coronary artery with L-NMMA also tended to be attenuated in patients with heart failure. In summary, vasoconstricting response to L-NMMA was blunted in the coronary resistance artery in heart failure in vivo. These findings suggest that basal release of nitric oxide in the coronary circulation is decreased in patients with heart failure.

Adult↗
PubMed1997

Correlations between recruitable coronary collateral flow velocities, distal occlusion pressure, and electrocardiographic changes in patients undergoing angioplasty.

Direct assessment of coronary collateral flow has been difficult in humans. The goal of this study was to correlate the magnitudes and waveform characteristics of recruitable coronary collateral flow velocity measured with Doppler guidewire with other hemodynamic and functional indexes of collateral circulation in patients during angioplasty. Twenty-six patients [age 60 +/- 10 (SD) years] were studied for measurements of flow velocity at the distal segment of the dilated vessel. Collateral flow signals were demonstrated in 18 patients (69%) during balloon inflation. There was a weak yet significant positive correlation between the magnitude of collateral flow velocity and distal occlusion pressure (p < 0.01). The sum of ischemic ST elevation on the 12-lead electrocardiogram was inversely correlated with distal occlusion pressure, but not with the magnitude of collateral flow velocity. Subgroup analysis between patients with (n = 18) and without (n = 8) ST elevation during balloon inflation revealed higher collateral flow velocity signals (p < 0.0001) and greater systolic components of collateral flow in the latter group (p < 0.0001). Thus, functionally significant coronary collaterals showed greater velocity signals and systolic predominance in flow pattern. The functional capacity of human coronary collaterals may be semiquantitated using the Doppler guidewire technique.

Angina Pectoris↗
PubMed1997

[Utility of daily oral administration of etoposide in 25 cases of refractory hematological malignancies].

We estimated the utility of daily oral administration of etoposide (ETOP) in 25 cases of refractory hematological malignancies who had been admitted to our hospital between February, 1988 and October, 1995. Patients were 9 cases of malignant lymphoma, 7 cases of adult T cell leukemia (ATL), 7 cases of acute leukemia, 1 case of primary macroglobulinemia, and 1 case of chronic lymphocytic leukemia (CLL). Eight cases were elderly patients over 65 years old, 7 cases were refractory to previous chemotherapies, and 13 cases were relapsed cases. ETOP was administered at 25 or 50 mg per day for at least more than 3 consecutive weeks, if the peripheral white blood cell count exceeded 1,000/microliter. Complete and partial responses were obtained in 64% of all cases, especially in 81% of malignant lymphoma and ATL. Probability of survival for 3 years of malignant lymphoma and ATL was 36.7%. As mild toxicities, 2 cases (8%) had nausea and vomiting, 2 cases (8%) had diarrhea, and 3 cases (12%) had stomatitis. Grade 3 leukocytopenia was observed in 16% of cases. Twelve out of 16 evaluable patients recovered in performance status (PS) after this therapy. Daily oral administration of ETOP might be an effective therapy for refractory hematological malignancies, especially for malignant lymphoma.

Administration, Oral↗
PubMed1997

[Preoperative evaluation of the right ventricular function using the pulsed Doppler echocardiogram in the patients scheduled for the elective pulmonary resection].

Preoperative evaluation of the both right ventricular (RV) systolic and diastolic function using the pulsed Doppler echocardiogram were examined for 46 patients scheduled for the pulmonary resection of the pulmonary tumorous lesions. The parameters which included the RV inflow pattern at the tricuspid orifice and the RV ejection flow pattern at the RV outflow tract were obtained by the pulsed Doppler echocardiogram. Following results were obtained. 1) The RV afterload shown by the parameters of the acceleration time (AT, time beginning of RV ejection to peak velocity) were higher in the aged patients, the low FEV 1% populations, and the patients having the deteriorated left ventricular contraction. 2) The RV diastolic dysfunction were present preoperatively in aged patients over the 60 years old. This phenomenon was characterized by a high degree of atrial contraction and an increased ratio of the peak velocity in atrial contraction phase to that in early rapid filling phase (A/E). When we evaluate the RV inflow and ejection Doppler flow patterns after the major lung resection, these findings must be considerable thing.

Adolescent↗
PubMed1997

[Successful high-dose chemotherapy combined with autologous bone marrow transplantation in a case of refractory follicular lymphoma].

A 34-year-old patient with follicular lymphoma who was treated with CHOP followed by COPP for 3 years, became resistant to treatment in December 1993. Histological findings and surface markers of cervical lymph node cells revealed no change from previous findings. Tumor cell involvement of bone marrow was also observed by molecular analysis of DNA fragments with bcl-2 oncogene and J-H gene probes. Following 2 courses of salvage chemotherapy with NOAC-M regimen (novantrone, cytarabine and methylprednisolone), There was an 88% reduction of tumor mass on computed tomographic findings. Through the use of polymerase chain reaction analysis of residual cells with the bcl-2 translocation, we confirmed the in vivo purging of tumor cells from bone marrow and we harvested marrow cells for autologous transplantation. After high-dose chemotherapy (HDC) with ranimustine, cisplatin, etoposide and cyclophosphamide followed by bone marrow transplantation (BMT), complete remission was achieved. The patient has survived for 16 months and remains disease free. The standard chemotherapy regimen for advanced low grade non-Hodgkin's lymphoma has not yet been defined. Although we must follow this patient carefully to determine the effect of HDC with BMT for a long time, this seems to be an effective complementary treatment for patients responding to conventional salvage regimens.

Adult↗
PubMed1996

Effects of L-arginine supplementation on endothelium-dependent coronary vasodilation in patients with angina pectoris and normal coronary arteriograms.

BACKGROUND: The pathogenesis of impaired endothelium-dependent coronary vasodilation in angina pectoris and normal coronary arteriograms (microvascular angina pectoris) is not known. We examined whether supplementation with L-arginine, a precursor of endothelium-derived nitric oxide, improves endothelium-dependent coronary vasodilation in patients with microvascular angina. METHODS AND RESULTS: The effect of intracoronary infusion of L-arginine (50 mg/mm) on acetylcholine-induced coronary vasomotion was studied in eight patients with microvascular angina and eight control subjects. The responses of the large epicardial coronary artery diameter and coronary blood flow were measured with coronary arteriography and an intracoronary Doppler catheter, respectively. Acetylcholine increased coronary blood flow with modest vasoconstriction of the large coronary artery without altering arterial pressure and heart rate. The acetylcholine-induced increases in coronary blood flow were significantly less (P < .01) in patients than in control subjects. L-Arginine significantly augmented the coronary blood flow responses to acetylcholine in patients, but not in control subjects. L-Arginine did not alter responses of the large coronary artery in either group. CONCLUSIONS: Study results suggest that L-arginine improved endothelium-dependent vasodilation of coronary microcirculation in patients with microvascular angina pectoris.

Acetylcholine↗
PubMed1996

Altered serotonin receptor subtypes mediate coronary microvascular hyperreactivity in pigs with chronic inhibition of nitric oxide synthesis.

BACKGROUND: We previously reported that chronic inhibition of nitric oxide synthesis by administration of N omega-nitro-L-arginine methyl ester (L-NAME) causes microvascular hyperreactivity to 5-hydroxytryptamine (5-HT) and vascular structural changes in pigs in vivo. In the present study, we investigated the relative contributions of 5-HT receptor subtypes to microvascular hyper-reactivity in this animal model. METHODS AND RESULTS: Coronary vasomotor response was studied in 16 pigs treated with oral L-NAME for 4 weeks (L group) and in 11 control pigs (C group). Intracoronary administration of 5-HT at 30 micrograms/kg decreased coronary blood flow (CBF) in the two groups. The decrease in CBF by 5-HT was greater (P < .01) in the L group than in the C group. The decrease in CBF by 5-HT in the C group was blocked completely by pretreatment with ketanserin, a 5-HT2 antagonist. In contrast, the augmented decrease in CBF by 5-HT in the L group was only partly inhibited by ketanserin alone and was blocked completely by ketanserin and methiothepin, a 5-HT1/5-HT2 antagonist. The decrease in CBF caused by prostaglandin F2 alpha and the increase in CBF caused by nitroglycerin were comparable between the two groups and were not affected by the 5-HT antagonists. CONCLUSIONS: These results suggest that the 5-HT-induced microvascular hyperreactivity may be mediated by relative changes in affinity for 5-HT receptors or de novo expression of 5-HT1 receptors in microvascular smooth muscle cells in our animal model.

Animals↗