Biomedical subjects

Hatsumi Yamamoto

Publications and source records attributed to Hatsumi Yamamoto.

9 recordsLinked to original sources

PubMed2007

Identification of alpha-1L and alpha-1A adrenoceptors in human prostate by tissue segment binding.

PURPOSE: Silodosin (KMD-3213 or [(-)-1-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-1H-indole-7-carboxamide]) (Kissei Pharmaceutical Co., Ltd., Matsumoto, Japan) is a selective antagonist for alpha-1A and alpha-1L adrenoceptors. Using this tritiated ligand the 2 alpha-1 adrenoceptors were examined in binding studies with intact tissue segments and membrane preparations of human prostate, and compared with functionally identified alpha-1 adrenoceptor. MATERIALS AND METHODS: Binding assays with tissue segments and membrane preparations of human prostate samples were performed using [3H]-silodosin and binding affinities for various drugs were estimated. In functional experiments antagonist affinities were evaluated from the inhibitory potency against the contractile response to noradrenaline. RESULTS: [3H]-silodosin bound to intact segments and membrane preparations of human prostate with subnanomolar affinity. [3H]-silodosin binding sites in intact segments were divided into 2 distinct components with different affinities for prazosin and RS-17053 (N-[2(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha, alpha-dimethyl1H-indole-3-ethanamine hydrochloride) (Research Biochemicals International, Natick, Massachusetts), while binding in membrane preparations showed single high affinity for these drugs. [3H]-silodosin binding sites also showed high affinity for silodosin and tamsulosin but low sensitivity to BMY 7378 (8-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-8-azaspiro(4.5)decane-7,9-dione) (Research Biochemicals International) in intact segments and in membrane preparations. In functional experiments silodosin and tamsulosin potently inhibited the contractile response to noradrenaline but prazosin, RS-17053 and BMY 7378 showed low antagonistic affinity. CONCLUSIONS: The current binding studies in human prostate samples clearly show that alpha-1L and alpha-1A adrenoceptors coexist as pharmacologically distinct entities in intact tissues but not in crude membrane preparations. Also, alpha-1 adrenoceptors involved in the contractile response to noradrenaline are the alpha-1L subtype.

Humans↗

PubMed2006

Emergence of physiological rhythmicity in term and preterm neonates in a neonatal intensive care unit.

BACKGROUND: Biological rhythmicity, particularly circadian rhythmicity, is considered to be a key mechanism in the maintenance of physiological function. Very little is known, however, about biological rhythmicity pattern in preterm and term neonates in neonatal intensive care units (NICU). In this study, we investigated whether term and preterm neonates admitted to NICU exhibit biological rhythmicity during the neonatal period. METHODS: Twenty-four-hour continuous recording of four physiological variables (heart rate: HR recorded by electrocardiogram; pulse rate: PR recorded by pulse oxymetry; respiratory rate: RR; and oxygen saturation of pulse oxymetry: SpO2) was conducted on 187 neonates in NICU during 0-21 days of postnatal age (PNA). Rhythmicity was analyzed by spectral analysis (SPSS procedure Spectra). The Fisher test was performed to test the statistical significance of the cycles. The cycle with the largest peak of the periodogram intensities was determined as dominant cycle and confirmed by Fourier analysis. The amplitudes and amplitude indexes for each dominant cycle were calculated. RESULTS: Circadian cycles were observed among 23.8% neonates in HR, 20% in PR, 27.8% in RR and 16% in SpO2 in 0-3 days of PNA. Percentages of circadian cycles were the highest (40%) at < 28 wks of gestational age (GA), decreasing with GA, and the lowest (14.3%) at > or = 37 wks GA within 3 days of PNA in PR and were decreased in the later PNA. An increase of the amplitude with GA was observed in PR, and significant group differences were present in all periods. Amplitudes and amplitude indexes were positively correlated with postconceptional age (PCA) in PR (p < 0.001). Among clinical parameters, oxygen administration showed significant association (p < 0.05) with circadian rhythms of PR in the first 3 days of life. CONCLUSION: Whereas circadian rhythmicity in neonates may result from maternal influence, the increase of amplitude indexes in PR with PCA may be related to physiological maturity. Further studies are needed to elucidate the effect of oxygenation on physiological rhythmicity in neonates.

Journal Article↗

PubMed2006

Discrimination of acute graft-versus-host disease from infections by enumeration of peripheral blood interferon-gamma spot-forming cells.

Infections may coexist and in certain circumstances aggravate acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation. Early detection of aGVHD is often difficult in patients with concurrent infections. Using an enzyme-linked immunospot assay that reflects ongoing immune status in vivo, we enumerated spot-forming cells (SFCs) for interferon (IFN)-gamma, interleukin (IL)-4, and IL-12 in peripheral blood from 56 patients with hematological disorders. Eleven patients had viral, fungal, or bacterial systemic infections during first 10 weeks posttransplant. Of these, six patients with grade 0-I aGVHD showed normal levels of IFN-gamma SFCs. On the other hand, IFN-gamma SFCs were elevated in five patients with grade II-IV aGVHD. These data indicate that increased IFN-gamma SFCs seemed to be correlated with clinically significant aGVHD, but not with infection itself. IL-4 and IL-12 SFCs increased in some patients with infections, irrespective of the presence of aGVHD. Thus, IFN-gamma SFCs may be used to distinguish systemic infections from aGVHD.

Acute Disease↗

PubMed2006

[Alpha1-adrenoceptor subtypes and alpha1-adrenoceptor antagonists].

Alpha(1)-adrenoceptors are widely distributed in the human body and play important physiologic roles. Three alpha(1)-adrenoceptor subtypes (alpha(1A), alpha(1B) and alpha(1D)) have been cloned and show different pharmacologic profiles. In addition, a putative alpha(1)-adrenoceptor (alpha(1L) subtype) has also been proposed. Recently, three drugs (tamsulosin, naftopidil, and silodosin) have been developed in Japan for the treatment of urinary obstruction in patients with benign prostatic hyperplasia. In this review, we describe recent alpha(1)-adrenoceptor subclassifications and the pharmacologic characteristics (subtype selectivity and clinical relevance) of alpha(1)-adrenoceptor antagonists.

Adrenergic alpha-1 Receptor Antagonists↗

PubMed2005

Quantifying receptor properties: the tissue segment binding method - a powerful tool for the pharmacome analysis of native receptors.

The radioligand binding assay technique is an extremely powerful tool for studying receptors. It allows an analysis of the interactions of hormones, neurotransmitters, and related drugs with their receptors. Most of the binding assays have widely been applied to crude membrane fractions prepared from many tissues, but in the conventional method, there are some limitations such as a yield loss of receptor-bearing membranes and a change in receptor environment upon homogenization and fractionation. Recently, in order to overcome these problems, a binding assay has been developed using intact tissue segments. This article presents a brief overview of the tissue segment binding assay that has been developed mainly in our department. Practical guidelines for setting up this new assay are presented, including segment preparation, choice of appropriate radioligand, optimizing assay conditions, and appropriate methods for data analysis. The unique advantages and disadvantages of the tissue segment binding method are discussed in comparison with those of conventional membrane binding methods. We suggest that the tissue segment binding method is a powerful tool for detecting the native properties of receptors occurring in tissues and cells without altering their environment.

Animals↗

PubMed2005

Prediction of acute graft-versus-host disease and detection of distinct end-organ targets by enumeration of peripheral blood cytokine spot-forming cells.

BACKGROUND: Acute graft-versus-host disease (aGVHD) remains a significant cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. It was hypothesized that type 1 cytokines promoted aGVHD and type 2 cytokines inhibited it. However, recent publications demonstrated contradictory results in murine models. Type 1/2 paradigm in aGVHD remains to be determined in human. METHODS: Using enzyme-linked immunospot assay that reflects ongoing immune status in vivo, we measured spot-forming cells (SFCs) for interferon (IFN)-gamma, interleukin (IL)-12, IL-4, and IL-10 in peripheral blood from 56 patients with hematological disorders who underwent allogeneic hematopoietic stem cell transplantation. RESULTS: The numbers of IFN-gamma and IL-4 SFCs in patients with grade II approximately IV aGVHD were significantly higher than those in patients with grade 0 approximately I aGVHD. The enumeration of cytokine SFCs predicted aGVHD approximately 4 days before it became clinically evident, since IFN-gamma SFCs in asymptomatic phase that later progressed into grade II approximately IV aGVHD were elevated in 8 out of 8 evaluable patients. Similarly, IL-4 SFCs were elevated in 6 of 8 patients. In addition, Type 1 cytokine SFCs contributed to the intestinal, but not skin and hepatic aGVHD. CONCLUSIONS: Enzyme-linked immunospot assay is clinically useful for predicting aGVHD and detecting distinct end-organ targets following allogeneic hematopoietic stem cell transplantation.

Acute Disease↗

PubMed2004

Identification of alpha-1L adrenoceptor in rabbit ear artery.

The alpha-1L adrenoceptor (AR) was identified in rabbit ear artery by both functional and ligand binding studies. In functional studies using arterial rings, the contractile response to NS-49 [(R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluorometh-anesulfonanilide hydrochloride] (alpha-1A and alpha-1L AR-selective agonist) was competitively antagonized with low affinities by prazosin, RS-17053 [N-[2-(2-cyclopropylmethoxyphenoxy) ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethamine hydrochloride], and 5-methylurapidil but with high affinities by tamsulosin and KMD-3213 [(-)-1-(3-hydroxypropyl)-5-[(2R)-2-([2-[(2,2,2-trifluoroethoxy)phenoxy]ethyl]amino)propyl]-2,3-dihydro-1H-indole-7-carboxamide]. In contrast, the response to noradrenaline (nonselective alpha-1 AR agonist) was inhibited noncompetitively by these antagonists (except 5-methylurapidil) with Schild slopes different from unity. These results suggest that the response to NS-49 was mediated predominantly via alpha-1L ARs, whereas the response to noradrenaline was produced through two distinct alpha-1 AR subtypes (presumably alpha-1B and alpha-1L ARs). In binding studies with intact segments of rabbit ear artery, [3H]KMD-3213 bound with high affinity (pKD=9.7) to alpha-1 ARs, which were subdivided by prazosin, RS-17053, and 5-methylurapidil into two subtypes (alpha-1A and alpha-1L ARs). In contrast, [3H]prazosin binding sites in ear artery segments (pKD = 9.8) were identified as alpha-1A and alpha-1B ARs. In conventional binding studies using isolated rabbit ear artery microsomal membranes, [3H]KMD-3213 binding sites were identified as alpha-1A ARs with high affinities for prazosin, RS-17053, and 5-methylurapidil. Our study indicates that an alpha-1L AR having a unique pharmacological profile coexists with alpha-1A and alpha-1B ARs in rabbit ear artery and can be identified either functionally or by binding studies using intact tissues but not microsomal membrane preparations.

Adrenergic alpha-Antagonists↗

PubMed2003

Expression of short-form caspase 8 correlates with decreased sensitivity to Fas-mediated apoptosis in neuroblastoma cells.

Disruption of apoptotic death signal transduction pathways may be responsible for tumor formation, progression and resistance to treatment in neuroblastoma. Caspase 8, one of the initiator caspases, plays an important role in the Fas-Fas ligand pathway. This caspase signals through the formation of a death-inducing signaling complex in response to Fas activation by its ligand. In this study, we evaluated the sensitivity of a series of human neuroblastoma cell lines to membrane-bound Fas ligand induced-cell death, as well as the expression of Fas, caspase 3 and caspase 8. Sensitivity to Fas-mediated cell death did not correlate with the expression of Fas in neuroblastoma cells, but was directly associated with the pattern of caspase 8 protein expression. We found that the majority of neuroblastoma cell lines we evaluated lacked caspase 8 expression, and these cell lines were invariably resistant to Fas-mediated cell death. In contrast, cell lines expressing normal caspase 8 protein were quite sensitive to Fas-mediated cell death. More interestingly, a group of cell lines expressing a distinct short form of caspase 8 with splicing out of exon 3 consistently showed moderate sensitivity to Fas-mediated cell death. These results indicate that the profile of caspase 8 expression is an important determinant of the response of neuroblastoma cells to Fas-mediated cell death.

Alternative Splicing↗

PubMed2002

The role of donor age in naive T-cell recovery following allogeneic hematopoietic stem cell transplantation: the younger the better.

The high incidence of opportunistic infections after unrelated bone marrow transplantation has been reported. Delayed lymphocyte recovery may be associated with opportunistic infections. Immune reconstitution is influenced by recipient age and graft-vs-host disease. However, the role of donor age is largely unknown. When the effect of donor age on lymphocyte reconstitution post-transplant was examined in the murine allogeneic hematopoietic stem cell transplantation, the recovery of CD4+ naive T-cells in early post-transplant period was correlated inversely with donor age. Clinically, recipient mice transplanted from younger donors showed significantly higher survival rate and mitogenic responses than adult donors. Since CD4+ naive T-cells are mainly involved in primary immune responses to newly encountered antigens and play an important role in host defense, faster recovery of CD4+ naive T-cells in younger donors may contribute to the reduced mortality in early post-transplant period. Therefore, it is better to choose a younger donor if sufficient cell dose is available. In this review, age-related changes in hematopoiesis and lymphopoiesis as well as thymus-dependent and thymus-independent pathways following allogeneic hematopoietic stem cell transplantation are discussed.

Age Factors↗