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Biomedical subjects

H Itoh

Publications and source records attributed to H Itoh.

At least 217 records · Page 12Linked to original sources
PubMed2000

End-tidal CO2 pressure decreases during exercise in cardiac patients: association with severity of heart failure and cardiac output reserve.

OBJECTIVES: We measured end-tidal CO2 pressure (PETCO2) during exercise and investigated the relationship between PETCO2 and exercise capacity, ventilatory parameters and cardiac output to determine the mechanism(s) of changes in this parameter. BACKGROUND: It is unclear whether PETCO2 is abnormal at rest and during exercise in cardiac patients. METHODS: Cardiac patients (n = 112) and normal individuals (n = 29) performed exercise tests with breath-by-breath gas analysis, and measurement of cardiac output and arterial blood gases. RESULTS: PETCO2 was lower in patients than in normal subjects at rest and decreased as the New York Heart Association class increased, whereas the partial pressure of arterial CO2 did not differ among groups. Although PETCO2 increased during exercise in patients, it remained lower than in normal subjects. PETCO2 in relation to cardiac output was similar in patients and normal subjects. PETCO2 at the respiratory compensation point was positively correlated with the O2 uptake (r = 0.583, p < 0.0001) and the cardiac index at peak exercise (r = 0.582, p < 0.0001), and was negatively correlated with the ratio of physiological dead space to the tidal volume. The sensitivity and specificity of PETCO2 to predict an inadequate cardiac output were 76.6% and 75%, respectively, when PETCO2 at respiratory compensation point and a cardiac index at peak exercise that were less than the respective control mean-2 SD values were considered to be abnormal. CONCLUSIONS: PETCO2 was below normal in cardiac patients at rest and during exercise. PETCO2 was correlated with exercise capacity and cardiac output during exercise, and the sensitivity and specificity of PETCO2 regarding decreased cardiac output were good. PETCO2 may be a new ventilatory abnormality marker that reflects impaired cardiac output response to exercise in cardiac patients diagnosed with heart failure.

Anaerobic Threshold↗
PubMed2000

Current topics in pheochromocytoma.

Pheochromocytoma is the tumor that produces catecholamines and originates from chromaffin cells, which are differentiated from sympathoadrenal progenitor cells of neural crest under the influence of glucocorticoids. Genetic abnormalities of familial pheochromocytomas have elucidated oncogenic genetic bases of the tumor, including gene abnormalities of the RET proto-oncogene in multiple endocrine neoplasia type 2, VHL gene in von Hippel Lindau's disease or the NF1 gene in neurofibromatosis. Co-localization of various substances with catecholamines in the tumor, including neuropeptide Y, opioid peptides or adrenomedulOFF peptide elevating cAMP production, is recognized. The significance of these substances in modulating clinical features of pheochromocytomas is not fully understood.

Adrenal Gland Neoplasms↗
PubMed2000

Nitric oxide is an excitatory modulator in the rostral ventrolateral medulla in rats.

Nitric oxide is a messenger molecule having various functions in the brain. Previous studies have reported conflicting results for the roles of nitric oxide in the rostral ventrolateral medulla, a major center that regulates sympathetic and cardiovascular activities. We hypothesized that in this region, nitric oxide may have a biphasic effect on cardiovascular activity. Microinjection of a low dose (1 nmol) of a nitric oxide donor sodium nitroprusside or a cyclic GMP agonist 8-bromocyclic GMP into this area increased arterial pressure, whereas injection of a nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester or a soluble guanylate cyclase inhibitor methylene blue decreased arterial pressure. Microinjection of a high dose (100 nmol) of sodium nitroprusside decreased arterial pressure and inhibited spontaneous respiration with concomitant production of peroxynitrite, a strong cytotoxic oxidant. Increases in arterial pressure caused by microinjection of L-glutamate were inhibited after preinjection of Nomega-nitro-L-arginine methyl ester or methylene blue. Increases in arterial pressure caused by microinjection of sodium nitroprusside (1 nmol) were inhibited after preinjection of a glutamate receptor antagonist kynurenate. These results suggest that low doses of nitric oxide may increase arterial pressure, whereas high doses of nitric oxide may decrease arterial pressure through cytotoxic effects in the rostral ventrolateral medulla. They also indicate that nitric oxide may stimulate neurons both through activation of the nitric oxide cyclic GMP pathway and through modulation of glutamate receptor stimulation, and therefore, increase arterial pressure in rats.

Animals↗
PubMed2000

Modulation of endothelin-1 coronary vasoconstriction in spontaneously hypertensive rats by the nitric oxide system.

To determine whether nitric oxide contributes to the augmented vasoconstrictive response to endothelin-1 (ET-1) in coronary vessels of hypertensive hearts, and also whether L-arginine administration can inhibit the augmented response to ET-1, we designed experiments to measure coronary perfusion resistance in isolated hearts of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) with or without L-arginine administration (0.5 g/L) for 2 weeks. The hearts were paced at a constant rate and perfused by the Langendorff technique at constant pressure (75 mm Hg). Perfusion flow and pressure were monitored, and coronary vascular resistance (CVR) was calculated. ET-1 infusion elicited dose-dependent increases in CVR in both WKY and SHR. At an ET-1 concentration of 1.5 x 10(-9) mol/L, the response was significantly greater in SHR. In L-NAME-treated WKY and SHR, responses to ET-1 were augmented, compared with those of nontreated rats, and this augmentation was greater in WKY. L-arginine administration reduced the CVR response to ET-1 in SHR, whereas it did not change responses to ET-1 in WKY. These findings suggest that the augmented vasoconstriction of the coronary artery induced by ET-1 in hypertensive hearts was due to a reduction in nitric oxide release in coronary vessels and that L-arginine can partially inhibit the vasoconstrictive response of the coronary artery.

Animals↗
PubMed2000

Loperamide therapy in a patient with diarrhea and resistant hypertension.

A 65-year-old man was admitted to our hospital for resistant essential hypertension. He had a past history of bowel resections due to Crohn's disease. We assumed that in this patient insufficient drug absorption might be a cause of resistant hypertension and that even increased antihypertensive regimens would fail to decrease blood pressure. We administered loperamide, which may increase drug absorption from the residual intestine. Blood pressure was successfully decreased, with a concomitant increase in blood concentration of antihypertensive drugs. In patients with impaired drug absorption, we should make an effort to restore drug obstruction before considering increased drug regimens.

Aged↗
PubMed2000

Specific preinduction of 60-kDa heat shock protein (chaperonin homolog) by TRH does not protect colonic mucosa against acetic acid-induced lesion in rats.

In order to study the cytoprotective function of colonic heat shock proteins (HSPs) in vivo, the effect of specific preinduction of HSP60 by thyrotropin-releasing hormone (TRH) administration on the development of acetic acid-induced colonic mucosal lesion was investigated. Expression of 60-kDa, 72-kDa, and 90-kDa heat shock proteins (HSP60, HSP72, and HSP90, respectively) in rat colonic mucosa was investigated by western blot and immunohistochemical analyses before and after TRH administration. Following pretreatment with or without TRH administration, the rats received intrarectal infusion of 5% acetic acid. The colonic mucosal damage was macroscopically evaluated 24 hr after the intrarectal infusion of acetic acid. Expression of HSP60 was significantly increased by TRH administration in the colonic mucosa, whereas HSP72 and HSP90 did not increase. Immunohistochemical study also showed a significant increase in HSP60 in colonic mucosal cells, especially at the surface of the colonic mucosa after TRH administration. No histopathologic alteration was observed in the colonic mucosa after TRH administration. The colonic mucosal damage caused by intrarectal infusion of 5% acetic acid was not prevented by preinduction of HSP60. We demonstrated that specific preinduction of HSP60 by TRH administration did not show cytoprotective function in the colonic mucosa, although this protein plays a crucial role for cytoprotection in the pancreatic acinar cells. Our results indicate that the role of HSP60 may be different in each organ with respect to cytoprotection.

Acetic Acid↗
PubMed2000

Cell kinetic study of normal human bone marrow hematopoiesis and acute leukemia using 7AAD/PY.

We have used the 7AAD/PY method to analyze the cell cycle status of normal human bone marrow hematopoiesis, and found that the cell kinetics differed. There were cells with relatively low levels of RNA in the S-phase (Type I) and a high level in the S-phase (Type 11). T-cells, B-cells, nucleated red cells and CD34+/CD19+ early B-cells in bone marrow were Type I, whereas myelomonocytic subset and CD34+/CD33-dim+ common myeloid cells were Type II. AC133+/CD38-dim cells, which were thought to be lineage-marker negative hematopoietic stem cells, had intermediate amounts of RNA in the S-phase between Type I and II (Type 0). Seventy-four cases of acute leukemia were also analyzed. Most of the T- and B-ALL cases were found to be Type I, most of the ANLL cases were Type II, and there were 10 cases that were Type 0. These findings yielded fundamental information about normal hematopoiesis and acute leukemia.

Adult↗
PubMed2000

Small Gtpase rab3A is associated with melanosomes in melanoma cells.

Rab3A is a small guanosine triphosphate (GTP)-binding protein that has been recently implicated in intracellular vesicle transport and the secretion of neurotransmitters in neuronal cells. We demonstrate here that Rab3A is associated with melanosomes in pigment cells. Rab3A as well as Rabphilin3A, a putative target protein of Rab3A, were detected in the melanosome fraction, purified from B16 murine melanoma cells by sucrose density gradient ultracentrifugation. In contrast, Rab GDP dissociation inhibitor (GDI), a GDP/GTP exchange protein for Rab3A, was found in the cytosol fraction. Further studies using confocal laser scanning microscopy and immunoelectron microscopy revealed that immunoreactive Rab3A is localized in conjunction with the melanosomal membrane. These results suggest the possibility of involvement of Rab3A-Rabphilin3A complex, regulated by Rab GDI, in the intracellular transport of melanosomes in pigment cells.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Pressor response to pulsatile compression of the rostral ventrolateral medulla mediated by nitric oxide and c-fos expression.

It has been reported that neurovascular compression of the rostral ventrolateral medulla might be causally related to essential hypertension. Recently, we found that pulsatile compression of the rostral ventrolateral medulla increases sympathetic nerve activity and elevates arterial pressure via activation of glutamate receptors in rats. We also found that increases in sympathetic and cardiovascular activities by microinjection of L-glutamate into the rostral ventrolateral medulla are mediated by c-fos expression-related substance(s) following activation of the nitric oxide-cyclic GMP pathway. Herein, we investigated whether responses to pulsatile compression are mediated by local activation of the nitric oxide-cyclic GMP pathway and/or c-fos expression-related substance(s) in rats. Increases in arterial pressure (15+/-1 mmHg), heart rate (9+/-1 b.p.m.), and sympathetic nerve activity (% change: 8.5+/-1.1%) induced by pulsatile compression were partially but significantly inhibited after local microinjection of a nitric oxide synthase inhibitor, L-N(G)-nitroarginine methyl ester (8+/-2 mmHg, 1+/-1 b.p.m., 4.0+/-1.3%; P<0.05 vs compression without pretreatment) or 7-nitroindazole (7+/-2 mmHg, 2+/-1 b.p.m., 4.0+/-1. 5%; P<0.05), or a soluble guanylate cyclase inhibitor, methylene blue (9+/-1 mmHg, 4+/-1 b.p.m., 4.1+/-1.4%; P<0.05). In addition, increases in arterial pressure, heart rate, and sympathetic nerve activity by pulsatile compression were significantly reduced 6 h after microinjection of antisense oligodeoxynucleotide to c-fos mRNA (2+/-2 mmHg, 2+/-1 b.p.m., 1.0+/-1.0%; P<0.05 vs sense oligodeoxynucleotide). These results suggest that increases in sympathetic and cardiovascular activities induced by pulsatile compression of the rostral ventrolateral medulla are mediated, at least in part, by local activation of the nitric oxide-cyclic GMP pathway and c-fos expression-related substance(s) in rats.

Animals↗
PubMed2000

LUCA15, a putative tumour suppressor gene encoding an RNA-binding nuclear protein, is down-regulated in ras-transformed Rat-1 cells.

BACKGROUND: The proliferation of mammalian cells is controlled by various intracellular mitogenic signalling pathways. In the intracellular pathways, Ras is involved in the activation of proto-oncogenes such as an immediate early gene c-fos. The somatic mutations of ras genes that elicit the constitutive activation of Ras have been found in tumours. Although these findings suggest that the constitutive activation of Ras-mediated pathways alters the expression of a set of genes involving tumorigenesis, these genes have not yet fully been studied. RESULTS: To study the up- or down-regulated genes in ras-transformed cells, we analysed Rat-1 transfectants expressing Ras(G12V) mutant protein in response to isopropyl-1-beta-thio-D-galactoside using a differential display. We found that the mRNA level of rat homologue of LUCA15, which has been cloned initially as a putative tumour suppressor gene mapped on human chromosome 3, was down-regulated by the expression of Ras(G12V). Epitope-tagged LUCA15 protein was localized in nuclei and had the ability to bind poly(G) RNA homopolymers in vitro. Moreover, ectopic expression of LUCA15 in human fibrosarcoma HT1080 cells suppressed the cell growth. CONCLUSION: These results demonstrate that LUCA15 is one of the down-regulated genes in ras-transformed cells, and suggests that LUCA15 may function as a negative regulator of cell proliferation by the alteration of its mRNA level.

Animals↗
PubMed2000

Germ cell-specific heat shock protein 105 binds to p53 in a temperature-sensitive manner in rat testis.

Heat shock protein (HSP)105 is a testis-specific and HSP90-related protein. The aim of this study was to explore the functions of HSP105 in the rat testis. Signals of HSP105 were detected immunohistochemically in the germ cells and translocated from the cytoplasm to the nucleus at 2 days after experimental induction of cryptorchidism. In cultured testicular germ cells, a significant increase in the expression of HSP105 in response to heat stress (37 degrees C) was detected in the insoluble protein fractions. Several binding proteins were isolated from rat testis using a HSP105 antibody immunoaffinity column, and p53, the tumor suppressor gene product, was copurified with these. Furthermore, immunoprecipitation using antibodies to p53 led to coprecipitation of HSP105 together with p53 after culturing germ cells at 32.5 degrees C, but not at 37 or 42 degrees C. In conclusion, HSP105 is specifically localized in the germ cells and may translocate into the nucleus after heat shock. HSP105 is suggested to form a complex with p53 at the scrotal temperature, and dissociate from it at suprascrotal temperatures. At scrotal temperature, HSP105 may thus contribute to the stabilization of p53 proteins in the cytoplasm of the germ cells, preventing the potential induction of apoptosis by p53.

Animals↗
PubMed2000

Genomic structure and chromosomal localization of the human hepatocyte growth factor activator inhibitor type 1 and 2 genes.

Hepatocyte growth factor activator inhibitor type 1 (HAI-1) and type 2 (HAI-2) are recently discovered Kunitz-type serine protease inhibitors which can be purified and cloned from human stomach cancer cell line MKN45 as specific inhibitors against hepatocyte growth factor activator (HGFA). HAI-2 was identical with the protein originally reported as placental bikunin. Both proteins contain two Kunitz inhibitor domains (KDs), of which the first domain (KD1) is mainly responsible for the inhibitory activity against HGFA, and are expressed ubiquitously in various tissues. In this study, we cloned the genes coding for these two structurally similar proteins by screening of human genomic bacterial artificial chromosome (BAC) library and their genomic structures were compared. HAI-1 and -2 genes consist of 11 and 8 exons spanning 12 kbp and 12.5 kbp, respectively. Three exons were inserted between KD1 and KD2 of each gene, of which the middle one was the low-density lipoprotein (LDL) receptor-like domain (HAI-1) and the testis specific exon (HAI-2). Apparently homologous regions between HAI-1 and -2 were not found in 5'-flanking region and neither TATA nor CAAT box was present. The genes were mapped to chromosome 15q15 (HAI-1) and 19q13.11 (HAI-2). These results suggested that although HAI-1 and -2 genes might be derived from same ancestor gene, they acquired distinctive in vivo roles during their evolution.

Amino Acid Sequence↗
PubMed2000

Anaesthetic and cardiopulmonary effects of balanced anaesthesia with medetomidine-midazolam and butorphanol in dogs.

The anaesthetic and cardiopulmonary effects of combinations of medetomidine (Me), midazolam (Mi) and butorphanol (Bu) were evaluated in dogs. The characterization of anaesthetic effects was assessed using a scoring system. The combinations tested were 20 or 40 micrograms/kg Me and 0.5 mg/kg Mi (20Me-Mi or 40Me-Mi) followed by either an intravenous injection of physiological saline solution (PSS) or Bu (0.1 or 0.3 mg/kg). The mixture of Me and Mi was injected intramuscularly, followed 15 min later by an intravenous injection of Bu or PSS in all six groups. The combined Me-Mi induced deep sedation but not profound anaesthesia. The effect of the subsequent Bu administration was observed in the scores related to its analgesic effect. There were no significant differences between the two doses of Bu, following either 20Me-Mi or 40Me-Mi in the duration of anaesthesia, heart and respiratory rates, rectal temperature, and anaesthetic and analgesic scores except for palpebral reflex, and interdigital web clamping scores. Therefore, we concluded that the addition of 0.1 mg/kg Bu to Me-Mi elicits adequate anaesthesia with adequate analgesic effect, and side-effects such as bradycardia, hypertension, and slight respiratory acidosis in some dogs.

Adrenergic alpha-Agonists↗
PubMed2000

Plasma human hepatocyte growth factor concentrations in patients with biliary obstruction.

BACKGROUND: It has been suggested that human hepatocyte growth factor (hHGF) maintains the growth and viability of hepatocytes and biliary epithelial cells. The purpose of this study was to determine plasma hHGF concentrations in patients with obstructive jaundice and to correlate these findings with clinical outcome. METHODS: The study included 22 patients who had biliary obstruction and underwent percutaneous transhepatic biliary drainage. The plasma concentrations of hHGF, standard liver function tests, daily bile flow and the half-life of serum total bilirubin were measured following the drainage. RESULTS: Plasma hHGF concentrations were significantly higher in patients with biliary obstruction compared with a control group (P<0.01). The plasma hHGF concentrations correlated with white cell count, prothrombin time and bilirubin half-life (P<0.05), but not with the values from other liver function tests. Seven patients who died within 3 months after biliary drainage had significantly higher concentrations of plasma hHGF than the 15 patients who survived for at least 3 months (P<0.05). The patients who experienced a poor outcome also had lower bile flows and prolonged bilirubin half-lives compared with the survivors (P<0.05). The plasma hHGF concentrations decreased significantly after biliary drainage in the survivors (P<0.01), but not in the patients with a poor outcome. CONCLUSIONS: These results suggest that systemic inflammation and the hepatic dysfunction caused by obstructive jaundice cause an increase in the plasma concentrations of hHGF. In addition, the plasma concentrations of hHGF may be a predictor of poor outcome in jaundiced patients.

Aged↗
PubMed2000

Clinical significance of urokinase-type plasminogen activator activity in hepatocellular carcinoma.

BACKGROUND AND METHODS: The plasminogen activation system plays a crucial role in the process of cancer invasion and metastasis. To evaluate the most effective factor in the invasion, metastasis and prognosis of hepatocellular carcinoma (HCC), we examined urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor (PAI)-1, PAI-2 and uPA activity by enzyme-linked immunosorbent assays (ELISA) in HCC tissues obtained from 46 patients. The results were compared with the patients' clinicopathological features and prognoses. RESULTS: Of the clinicopathological features, only histological portal involvement or intrahepatic metastasis, or both (INV), was significantly correlated to the disease-free survival rates (DFS; P < 0.05). The levels of uPA, PAI-1 and PAI-2 antigens were significantly associated with INV and histological grade. The DFS was not different, however, between cases with uPA, PAI-1 and PAI-2 values above and below the median. The high levels of uPA activity were closely related to INV (P < 0.001), and the activity gradually raised histological grades (P < 0.0001). The DFS was significantly different between patients with uPA activity below and above the median (0.70 ng/mL; P = 0.0092); it was also significantly different between such patients without INV (P < 0.05). CONCLUSIONS: Urokinase-type plasminogen activator activity may be the most sensitive factor affecting HCC invasion in the plasminogen activation system and a strong predictor for the recurrence of HCC. We suggest that cases with uPA activity of more than 0.70 ng/mL should be carefully followed up for possible HCC recurrence.

Adolescent↗
PubMed2000

Changes in subjective sleepiness, subjective fatigue and nocturnal sleep after anaesthesia with propofol.

The purpose of this study was to clarify the changes in psycho-physiological functions after anaesthesia with propofol (PF). The subjects were seven healthy male volunteers and the duration of the anaesthesia was 1 h (14:00-15:00 h). The plasma concentration of PF immediately decreased after the anaesthesia. The subjective sleepiness and VAS (visual liner analogue scale) scores (i.e. effort to do something) increased significantly at 20 min after the anaesthesia. However, these changes were improved at 80 min after the anaesthesia. The sleep latency at the nocturnal sleep 8 h after the anaesthesia was prolonged significantly, but the other parameters including the distributions of stage 3 + 4 and the rapid eye movement 'REM' stage were not changed.

Adult↗
PubMed2000

Sleep architectures of obstructive sleep apnea syndrome in the young child.

The sleep architectures of obstructive sleep apnea syndrome (OSAS) in the young child (child-OSAS, n = 17; mean age: 5.9+/-2.7 years; male:female 14:3) were compared with that of OSAS in the adult (n = 19; mean age: 44.7+/-10.7 years; male:female 18:1) and that of primary snoring in the child (n = 5; mean age: 7.0+/-2.4 years; male:female 5:0). Child-OSAS and OSAS in the adult had the same severity in oxygen desaturation. Child-OSAS showed lower Apnea-Hypopnea Index compared with OSAS in the adult. Sleep continuity in child-OSAS was not impaired compared with OSAS in the adult. Sleep fragmentation in child-OSAS was not so remarkable. The quantity of slow wave sleep in child-OSAS was similar to that of primary snoring in the child. Both profiles of sleep architectures showed nearly the same pattern.

Cerebral Cortex↗