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Biomedical subjects

K Nakao

Publications and source records attributed to K Nakao.

At least 37 records · Page 2Linked to original sources
PubMed2003

Enhanced antitumor effect of combined replicative adenovirus and nonreplicative adenovirus expressing interleukin-12 in an immunocompetent mouse model.

For cancer gene therapy, replicative adenovirus is a promising vector to overcome low infectivity and poor gene delivery of nonreplicative adenovirus in vivo, but its therapeutic efficacy is still unsatisfactory because of the limited spread of replicative virus in a solid tumor. Therefore, the combined therapy with other antitumor agents may be necessary. Nonreplicative adenovirus expressing a therapeutic gene may be a promising candidate because E1 proteins expressed by replicative adenovirus would render nonreplicative adenovirus replicative, augmenting a transgene expression. In this study, we first found that mouse hepatoma Hepa 1-6 cells were permissive for the replication and cytopathic effect of human adenovirus, which enabled us to examine the potential of combined replicative adenovirus and nonreplicative adenovirus expressing an immunostimulator in an immunocompetent mouse-syngeneic Hepa 1-6 tumor model. Nonreplicative adenovirus expressing interleukin-12 (AdIL-12) was used as a model. In vitro coinfection of two adenoviruses produced higher concentrations of IL-12 than infection of AdIL-12 alone in this cell line. In vivo experiments with Hepa 1-6 tumors in syngeneic immunocompetent C57BL/6 mice showed higher concentrations of serum IL-12 and greater therapeutic efficacy in the combination therapy than infection of either adenovirus. These data indicate that the combination of replicative adenovirus and nonreplicative adenovirus expressing an immunostimulator appears to be very efficacious for cancer gene therapy.

Adenoviridae↗
PubMed2003

Anti-obesity and anti-diabetic effects of brain-derived neurotrophic factor in rodent models of leptin resistance.

OBJECTIVE: Obesity in rodents and humans is mostly associated with elevated plasma leptin concentrations, suggesting a new pathological concept of 'leptin resistance'. We have demonstrated that brain-derived neurotrophic factor (BDNF) can improve obesity and diabetes of C57BL/KsJ db/db (db/db) mice. In this study, we investigated whether or not BDNF is effective in two different models of leptin resistance, an acquired model and a genetic model. DESIGN: C57BL/6J mice rendered obese by consumption of a high-fat diet (diet-induced obesity (DIO) mice) were used as an acquired model and lethal yellow agouti mice (KKA(y) mice) as a genetic model of leptin resistance. Food intake and glucose metabolism were studied after acute or repetitive administration of BDNF. RESULTS: Intraperitoneal administration of BDNF (10 mg/kg, twice/day) significantly reduced cumulative food intake of DIO and KKA(y) mice, whereas they were unresponsive to leptin administration. Repetitive subcutaneous administration of BDNF (10 mg/kg daily for 6 days) reduced food intake and improved impaired glucose tolerance in DIO mice. Pair feeding of vehicle-treated DIO mice with the same amount of chow consumed by the BDNF-treated group did not improve the impaired glucose homeostasis, indicating that the antidiabetic effect is not due to decreased food intake. We also observed that BDNF is effective in improving obesity and diabetes of KKA(y) mice. CONCLUSION: This study demonstrated antiobesity and antidiabetic effects of BDNF in two different models of leptin resistance, thereby suggesting the therapeutic potential of BDNF in the treatment of leptin-resistant obesity and diabetes.

Animals↗
PubMed2003

Chromosomal instability and human hepatocarcinogenesis.

Recently, many studies have identified losses and gains of several chromosomal loci in human hepatocellular carcinoma (HCC) with fine microsatellite analysis and comparative genomic hybridization. Although distribution of aberrant chromosomal arms differs among HCCs, loss of 1p, 4q, 6q, 8p, 9p, 10q, 13q, 16q and 17p, and gain of 1q, 6p, 8q, 17q and 20q have been recurrently reported, and loss of 4q and 16q seems to occur preferentially in hepatitis B virus-related HCCs. Accumulation of these aberrant chromosomal regions is associated with tumor progression, and some chromosomal aberrations, such as loss of 1p, are frequently identified in well-differentiated HCCs and also detected even in dysplastic nodule and cirrhotic nodule. This evidence suggests that chromosomal instability (CIN) emerges at an early stage during hepatocarcinogenesis and is successively inherent to tumor cells, resulting in acquisition of malignant phenotype. The molecular basis of CIN is beginning to be explored; however, several mechanisms may be involved for CIN of HCC.

Allelic Imbalance↗
PubMed2002

Relation between ultrasonographic and histologic findings of tracheal invasion by differentiated thyroid cancer.

Between 1988 and 1999 a total of 24 patients with differentiated thyroid cancer invading the airway underwent various types of tracheal resection at the Osaka Police Hospital. Preoperative ultrasonographic (US) findings in these patients were compared with postoperative histologic results of the resected specimens to confirm the relation between the preoperative and postoperative diagnoses and to determine the indications for operative procedures. Preoperative US revealed cancer invasion to the adventitia in 2 cases, to the intercartilage space in 13, and to the tracheal mucosa in 9. Histologically, cancer invasion to the adventitia was confirmed in 4, to the intercartilage space in 10, and to the mucosa in 10. Among 13 cancer invasion instances to the intercartilage revealed by US, overdiagnosis occurred in 3 cases and underdiagnosis in 1. The actual overall diagnostic rate by US was 83.3%, which is a great improvement over other available methods. In conclusion, preoperative US findings of the trachea agreed with the histologic findings of the resected specimens, indicating US to be the first choice when making decisions about resecting the trachea and about the operative procedure.

Carcinoma, Papillary↗
PubMed2002

Accelerated reendothelialization with suppressed thrombogenic property and neointimal hyperplasia of rabbit jugular vein grafts by adenovirus-mediated gene transfer of C-type natriuretic peptide.

BACKGROUND: Vein graft disease limits the late results of coronary revascularization. C-type natriuretic peptide (CNP) inhibits the growth of vascular smooth muscle cells. Given the effects of CNP on cGMP cascade, we hypothesized that transfected CNP genes modulate endothelial repair and thrombogenicity in the vein graft. METHODS AND RESULTS: Autologous rabbit jugular vein grafts were incubated ex vivo in a solution of adenovirus vectors containing CNP gene (Ad.CNP) or Escherichia coli lac Z gene (Ad.LacZ) and then interposed in the carotid artery. Reendothelialization, mural thrombi formation, and intima/media ratio were evaluated on the 14th and 28th postoperative days. More reendothelialization was seen in Ad.CNP-infected grafts than in Ad.LacZ-infected grafts both at 14 days (0.81+/-0.05 versus 0.30+/-0.14, P<0.01) and at 28 days (0.96+/-0.01 versus 0.45+/-0.08, P<0.001). The mural thrombus area was smaller in Ad.CNP-infected grafts than in Ad.LacZ-infected grafts. Neointimal thickening was significantly suppressed in the Ad.CNP group. The in vitro wound assay with human coronary artery endothelial cells revealed significant potentiation of the wound repair process by CNP and atrial natriuretic peptide administration. CONCLUSIONS: Infected Ad.CNP accelerated reendothelialization and suppressed thrombosis and neointimal hyperplasia. The method may potentially prevent vein graft disease in patients undergoing coronary artery revascularization.

Adenoviridae↗
PubMed2002

Clinical implications of leptin and its potential humoral regulators in long-term low-calorie diet therapy for obese humans.

OBJECTIVE: To address the clinical implications of leptin and to re-examine the relationship between leptin and its potential humoral regulators such as insulin, nonesterified fatty acids (NEFA) and triiodothyronine (T3) in low-calorie diet (LCD) for obese humans. DESIGN: Longitudinal study. SETTING: University and foundation hospitals. SUBJECTS: Ten obese men and 10 premenopausal obese women. INTERVENTIONS: Five men and five women took 800 kcal/day LCD and another five men and five women took 1400 kcal/day balanced deficit diet (BDD) during 4 weeks. RESULTS: Plasma leptin levels in the LCD group decreased more markedly (46.2+/-14.6 to 13.2+/-3.6 ng/ml) than that expected for the decrement in percentage fat (39.0+/-1.7 to 35.9+/-1.7%) and body mass index (BMI; 35.4+/-2.4 to 33.1+/-2.2 kg/m(2)), while that in the BDD group did not decrease significantly (14.9+/-3.5 to 13.4+/-2.8 ng/ml). The ratio of the decrease in leptin levels to that of BMI during the first week was significantly greater than that during the following 3 weeks (39.5+/-2.7 vs 29.3+/-2.1%, P=0.017). The plasma insulin and T3 levels also fell substantially in the first week and continued to decrease during the entire course. Plasma leptin levels measured weekly in each subject were correlated well with insulin (r=0.586, P=0.0003) and T3 (r=0.785, P=0.0004). Multiple regression analyses after adjustment for the time course and BMI revealed that serum levels of T3 were independently correlated with plasma leptin levels (r=0.928, P<0.0001). The plasma NEFA level was markedly elevated during the first 2 weeks and decreased thereafter. CONCLUSIONS: A rapid fall in leptin during the first week of LCD, coordinated by insulin, T3 and NEFA, should be beneficial for responding to decreased energy intake. Inversely, in view of the powerful effect of leptin on energy dissipation, the present findings suggest the potential usefulness of leptin in combination with caloric restriction for the treatment of obesity. SPONSORSHIP: The Ministry of Education, Culture, Sports, Science and Technology of Japan and the Ministry of Health, Labour and Welfare of Japan.

Adolescent↗
PubMed2002

Exercise prescription based upon cardiac vagal activity for middle-aged obese women.

OBJECTIVE: The purposes of this study were to examine a new method to determine exercise intensity for obese people based on the cardiac vagal activity and to determine the effect of this approach on myocardial stress. SUBJECTS: Forty-three middle aged obese female volunteers (age 43.7+/-6.5 y; height 1.56+/-0.05 m; body mass 66.5+/-9.3 kg; body mass index 27.3+/-2.8 kg m(2); percentage body fat 40.7+/-5.9%). MEASUREMENT: In the first experiment, 43 subjects performed a ramp exercise test on a bicycle ergometer with measurement of ECG and gas exchange parameters. In the second experiment, 11 subjects performed 45 min of constant walking exercise on a treadmill at a level corresponding to exercise intensity determined by vagal activity obtained from a ramp bicycle test. Blood pressure, endothelin 1 (ET-1), catecholamine, atrial natriuretic peptide (ANP), and brain natriuretic peptide (BNP) were measured before and after exercise. RESULTS: The heart rate variability power decreased with increasing work rate, and changed little after reaching individual-specific work rate. We presumed that vagal activity disappeared at this point and that the heart rate at this exercise intensity was determined as the vagal activity threshold (T(VA)). The results showed a significant positive correlation (r=0.742, P<0.0001) between T(VA) and ventilatory threshold (VT) heart rates, although the mean heart rate of T(VA) (114.3+/-8.5 beats/min) was significantly lower (P<0.001) than that at VT (119.0+/-11.7), suggesting the cardiac vagal withdrawal occurred prior to the onset of lactate acidosis (lactic acid accumulation). Furthermore, exercise intervention experiment at T(VA) indicated that ET-1, catecholamine and BNP levels were not significantly different before and after exercise. However, ANP levels increased significantly after exercise (pre-exercise 18.6+/-5.38 vs post-exercise 44.0+/-24.87 pg/ml, P<0.001), which in turn brought about a significant post-exercise reduction in the blood pressure (SBP 117.6+/-13.7 vs 110.5+/-7.4 mmHg, P<0.05; DBP 78.6+/-6.7 vs 73.5+/-6.6 mmHg, P<0.01). CONCLUSION: Our data suggest that it is possible to determine the exercise intensity (T(VA)) on the basis of cardiac vagal response. These results also suggest that exercise at T(VA) level is a safe exercise intensity in the light of cardiac stress, and that T(VA) may be recommended for obese people who might possess lower cardiac sympatho-vagal activity.

Adult↗
PubMed2002

Drug-induced neutropenia associated with anti-neutrophil cytoplasmic antibodies (ANCA): possible involvement of complement in granulocyte cytotoxicity.

Although antineutrophil antibodies are thought to be involved in drug-induced neutropenia, neither the precise mechanisms nor the particular antigens on the neutrophil surface have yet been clarified. Recently, we examined a patient with Graves' disease who developed antineutrophil cytoplasmic antibodies (ANCA) after propylthiouracil treatment and exhibited neutropenia. Because several target antigens of ANCA are expressed on the surface of neutrophils, it was suggested that ANCA might contribute to neutropenia. The patient's serum bound specifically to neutrophils and HL-60 cells differentiated into granulocytes, and lysed the HL-60 cells via a complement-mediated mechanism. Furthermore, two representative ANCA antigens, proteinase 3 and myeloperoxidase, significantly inhibited both the binding and cytotoxicity of the serum. Finally, tumour necrosis factor-alpha, which is known to up-regulate cell surface expression of several ANCA antigens, enhanced both the binding and cytotoxicity of the serum. These findings suggest that ANCA induced by propylthiouracil contributed to leucopenia through a complement-mediated mechanism.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2002

Leptin inhibits stress-induced apoptosis of T lymphocytes.

Leptin, which is secreted by adipocytes, the placenta and the stomach, not only controls appetite through leptin receptors in the hypothalamus but also regulates cell-mediated immunity. In this study we have demonstrated that continuous injection of leptin prevents the reduction in lymphocyte numbers normally observed in fasted and steroid-injected mice. Consistent with leptin-induced protection, we observed up-regulation of the bcl-xL gene as a result of signal transduction via leptin receptors on lymphocytes. We suggest that leptin might contribute to the recovery of immune suppression in malnourished mice by inhibiting lymphocyte apoptosis.

Animals↗
PubMed2002

Full-length sequence and functional analysis of hepatitis B virus genome in a virus carrier: a case report suggesting the impact of pre-S and core promoter mutations on the progression of the disease.

In chronic hepatitis B virus (HBV) infection, the quiescent immunotolerant phase evolves into the immunoactive phase. The aim of the present study was to clarify the virological alterations relevant to progression. Serial serum samples obtained from a patient with HBV during long-term follow-up were analysed by sequencing of the full-length HBV-DNA using polymerase chain reaction (PCR). In addition, PCR products of HBV genome from each serum sample were transfected into HuH-7 human hepatoma cells for the functional analysis of the transfected viral genomes. Based on the HBV-DNA sequence analysis, the patient had the genotype C virus, and the mutant HBV with common core promoter mutations (T(1762)A(1764)) and deletion of the pre-S region responsible for large surface protein transcription emerged before the onset of hepatitis. When the vigorous host immune response developed (indicated by the flare-up of hepatitis), the mutant HBV containing common core promoter mutations and another pre-S deletion causing lack of the surface protein promoter became predominant. The HBV-DNA sequences, other than pre-S and core promoter regions were identical to the wild-type sequence throughout the study. Transfection of PCR products containing the mutant HBV sequences resulted in increased amounts of intracellular replicative intermediates but the decreased secretion of HBsAg and HBeAg into culture media, suggesting accumulation of nonenveloped viral core particles within the cells. These results indicate that pre-S deletion and core promoter mutations may participate cooperatively in progression of the disease.

Adult↗
PubMed2002

Role of leptin in pregnancy--a review.

Leptin is an adipocyte-derived hormone that decreases food intake and body weight via its receptor in the hypothalamus. In rodents, it also modulates glucose metabolism by increasing insulin sensitivity. We previously reported that leptin is produced by human placental trophoblasts. We also revealed that leptin gene expression in the placenta was augmented in severe pre-eclampsia, and suggested that placental hypoxia may play a role in this augmentation. Maternal plasma leptin levels correlated well with mean blood pressure, but not with body mass index. Plasma leptin levels in pre-eclamptic women with IUGR were higher than those without IUGR (P< 0.05). We further examined the effects of hyperleptinemia on the course of pregnancy by using transgenic mice (Tg) overexpressing leptin. In pregnant Tg mice, food intake was significantly less than non-Tg, and the fetal body weights were reduced to approximately 70 per cent of those of non-Tg. Resistin is a novel adipocyte-derived hormone that decreases insulin sensitivity and increases plasma glucose concentration, thus contributing the development of obesity-related type II diabetes mellitus. We recently found that resistin gene is expressed in the human placenta as well as adipose tissue. In this review, possible roles of placental leptin and resistin are discussed.

Adult↗
PubMed2002

Plasma leptin levels and cardiac sympathetic function in patients with obstructive sleep apnoea-hypopnoea syndrome.

BACKGROUND: The control of body weight and cardiac sympathetic function in patients with obstructive sleep apnoea-hypopnoea syndrome (OSAHS) are important because both factors have significant effects on the mortality of these patients. It has recently been reported that OSAHS has a significant effect on the secretion of leptin, a hormone involved in the control of body weight and sympathetic nerve activity. In addition to the circadian rhythm of leptin secretion, the effects of one night of treatment with nasal continuous positive airway pressure (nCPAP) and the mechanism of the effects of nCPAP on nocturnal leptin secretion in patients with OSAHS has not yet been elucidated. METHODS: Blood samples were obtained at 21.00 hours, 00.00 hours, 03.00 hours, and 06.30 hours from 21 subjects with OSAHS (mean apnoea and hypopnoea index 52.4/h), with and without nCPAP treatment. Iodine-123 (I(123))-meta-iodobenzylguanidine (MIBG) imaging was used to evaluate myocardial sympathetic function before nCPAP treatment. RESULTS: Plasma leptin reached a peak level at 00:00 hours (p<0.01) in patients with OSAHS, both with and without nCPAP treatment. The first night of nCPAP treatment significantly decreased the plasma leptin levels at 03.00 hours (without nCPAP: mean (SE) 21.6 (4.7) ng/ml; with nCPAP: 19.3 (4.1) ng/ml, p<0.02) and at 06.30 hours (without nCPAP: 17.6 (3.8) ng/ml; with nCPAP: 15.2 (3.2) ng/ml, p<0.01). The magnitude of the decrease in leptin levels after nCPAP treatment was significantly correlated with cardiac sympathetic function measured before nCPAP treatment (p<0.03). CONCLUSIONS: Patients with OSAHS undergo nocturnal increases in leptin levels in spite of interruption of sleep due to apnoea and hypopnoea, a trend seen in normal subjects. Plasma leptin levels in patients with OSAHS decreased significantly after the first night of nCPAP treatment. Enhanced cardiac sympathetic function in these patients may contribute to the leptin levels before nCPAP treatment and vice versa.

3-Iodobenzylguanidine↗
PubMed2001

Human granulocyte-macrophage colony-stimulating factor (hGM-CSF) stimulates primitive and definitive erythropoiesis in mouse embryos expressing hGM-CSF receptors but not erythropoietin receptors.

Although erythropoietin (EPO) and its receptor (EPOR) are crucial for the proliferation, survival, and terminal differentiation of erythroid progenitors, it remains to be elucidated whether EPOR-unique signaling is required for erythropoiesis. To address this issue, human granulocyte-macrophage colony-stimulating factor (hGM-CSF) receptor (hGMR)-transgenic mice and heterozygous EPOR mutant mice were crossed by in vitro fertilization. In methylcellulose clonal culture of fetal liver (FL) cells of generated hGMR-expressing EPOR(-/-) embryos at embryonic day (E) 12.5 of gestation, hGM-CSF stimulated erythroid colony formation under serum-containing and serum-free conditions. Analysis of globin expression in individual erythrocyte-containing colonies formed from E12.5 FL cells showed that hGM-CSF supports primitive and definitive erythropoiesis even in EPOR(-/-) embryos. In comparison of activities between hGM-CSF and EPO in hGMR-expressing EPOR(+/+) embryos, the 2 substances supported the formation of similar numbers of erythroid colonies in clonal culture of E12.5 FL cells; enhanced adult, but not embryonic, globin synthesis; and induced increase of GATA-1 expression and decrease of erythroid Kruppel-like factor and cMyb expression in the FL cells. On the other hand, in E8.0 yolk sac erythropoiesis, both substances had a similar effect on erythroid colony formation, but hGM-CSF induced an increase of beta-major globin expression, while EPO did not. All together, the results of the present study demonstrated that hGM-CSF can stimulate the proliferation and differentiation of primitive and definitive erythroid cells independently of EPOR signal if they express hGMR, and the activity is comparable to that of EPO in definitive, but not primitive, erythropoiesis.

Animals↗
PubMed2001

Relationship between plasma level of cardiotrophin-1 and left ventricular mass index in patients with dilated cardiomyopathy.

OBJECTIVES: The study evaluated the relationship between plasma cardiotrophin-1 (CT-1) concentration and left ventricular (LV) mass in dilated cardiomyopathy (DCM) patients with congestive heart failure (CHF). BACKGROUND: Cardiotrophin-1 is a newly identified member of the interleukin-6 (IL-6) family of cytokines and one of the endogenous ligands for gp130 signaling pathways in the heart, and it has potent hypertrophic and survival effects on cardiac myocytes. However, the clinical significance of CT-1 is poorly understood. METHODS: We measured the plasma CT-1 level in 51 consecutive patients with DCM. Patients were classified into two groups: small LV mass index group and large LV mass index group, based on the median level of LV mass index. RESULTS: The plasma CT-1 level was increased in DCM patients with the severity of CHF and was significantly higher in the large LV mass group than in the small LV mass group, despite the absence of a difference in LV ejection fraction between the two groups. In addition, there was a significant positive correlation between the plasma CT-1 level and the LV mass index (r = 0.627, p < 0.0001). According to stepwise multivariate analyses among hemodynamic and neurohumoral factors, a high plasma CT-1 level showed an independent and significant positive relationship with a large LV mass index in patients with DCM. CONCLUSIONS: These results indicate that the plasma CT-1 level is increased in patients with DCM and is significantly correlated with the LV mass index, suggesting that CT-1 plays an important role in structural LV remodeling in patients with DCM.

Adolescent↗
PubMed2001

Retrovirus-mediated gene therapy for hepatocellular carcinoma with reversely oriented therapeutic gene expression regulated by alpha-fetoprotein enhancer/promoter.

In the present study, to achieve more selective and efficient therapeutic gene expression in hepatoma cells, we compared the therapeutic efficacies of the retroviral vectors expressing the herpes simplex virus thymidine kinase (HSV-tk) gene by the alpha-fetoprotein (AFP) enhancer/promoter in the forward (LNAFE0.3TK) and reverse (LN[AFE0.3TK]R) orientation to the vector long terminal repeats. By Northern blotting, the level of the HSV-tk mRNA in LN[AFE0.3TK]R-infected HepG2 human hepatoma cells was much higher than that in LNAFE0.3TK-infected cells. Consistent with this, LN[AFE0.3TK]R infection into HepG2 cells caused a greater cytotoxicity by ganciclovir exposure together with a stronger bystander effect than LNAFE0.3TK infection. In an animal model, intratumorous injection of LN[AFE0.3TK]R with ganciclovir treatment resulted in pronounced growth inhibition of HepG2 tumor. Thus, the reversely oriented therapeutic gene expression under the control of AFP enhancer/promoter is a possible candidate for the retrovirus-mediated gene therapy for hepatocellular carcinoma.

Animals↗
PubMed2001

Spontaneous tumorigenesis in mice defective in the MTH1 gene encoding 8-oxo-dGTPase.

Oxygen radicals, which can be produced through normal cellular metabolism, are thought to play an important role in mutagenesis and tumorigenesis. Among various classes of oxidative DNA damage, 8-oxo-7,8-dihydroguanine (8-oxoG) is most important because of its abundance and mutagenicity. The MTH1 gene encodes an enzyme that hydrolyzes 8-oxo-dGTP to monophosphate in the nucleotide pool, thereby preventing occurrence of transversion mutations. By means of gene targeting, we have established MTH1 gene-knockout cell lines and mice. When examined 18 months after birth, a greater number of tumors were formed in the lungs, livers, and stomachs of MTH1-deficient mice, as compared with wild-type mice. The MTH1-deficient mouse will provide a useful model for investigating the role of the MTH1 protein in normal conditions and under oxidative stress.

Adenocarcinoma↗
PubMed2001

Impaired delay but normal trace eyeblink conditioning in PLCbeta4 mutant mice.

To elucidate the functional role of phospholipase Cbeta4 (PLCbeta4), which is highly expressed in the Purkinje cells of the rostral cerebellum, cerebellar long-term depression (LTD) and delay and trace eyeblink conditioning were investigated in PLCbeta4-deficient mice. Rostral cerebellar LTD and delay eyeblink conditioning were severely impaired, whereas trace eyeblink conditioning was not. These results indicate that PLCbeta4 is essential for LTD in the rostral cerebellum and delay conditioning, but not trace conditioning. Rostral cerebellar LTD may be required as a neural substrate for delay conditioning, but is not required for trace conditioning.

Afferent Pathways↗