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Biomedical subjects

H Sakagami

Publications and source records attributed to H Sakagami.

At least 73 records · Page 4Linked to original sources
PubMed1997

Molecular cloning and developmental expression of a rat homologue of death-associated protein kinase in the nervous system.

Death-associated protein kinase (DAP kinase) has been recently identified as a novel Ca2+/calmodulin-dependent protein kinase and as a potential mediator of gamma interferon-induced cell death of Hela cells, which has cytological characteristics of the programmed cell death. In order to elucidate its functional roles in the rat brain where the programmed cell death is an essential mechanism in the organization of postmitotic neurons during development, we cloned a rat homologue of the human DAP kinase from the rat embryonic brain cDNA library. The deduced amino acid sequence was highly conserved between the two species (93.6%). By in situ hybridization histochemistry, the expression of DAP kinase mRNA was observed in the mantle and ventricular zones of the entire neuraxis on embryonic day 15. However, the overall expression in the brain decreased markedly after birth and the expression was maintained at substantial levels in several restricted mature neuronal populations, such as olfactory bulb, hippocampal formation and cerebellar Purkinje and granule cells. Its wide expression during development and its maintained expression in the restricted mature neuronal population suggest that DAP kinase might be involved in some neuronal functions beyond simply executing the developmental neuronal cell death.

Aging↗
PubMed1997

Induction of apoptotic cell death by direct-current treatment in human leukemic cell lines.

Exposure of human leukemic cell lines (HL-60, ML-1, U-937, MOLT-4, EOL-1) to short direct-current (d.c.) treatment induced apoptotic cell death, characterized by cell shrinkage and nuclear and internucleosomal DNA fragmentation. On the other hand, human peripheral blood lymphocytes and polymorphonuclear cells were relatively resistant to d.c. treatment, and did not show any clear nuclear and DNA fragmentation. The effect of d.c. was slightly reduced by calcium depletion, but was not significantly affected by catalase or by superoxide dismutase. The present data suggest that previously reported tumor regression activities of d.c. treatment might be due, at least in part, to its apoptosis-inducing activity.

Antioxidants↗
PubMed1997

Effect of glutathione-modulating compounds on hydrogen-peroxide-induced cytotoxicity in human glioblastoma and glioma cell lines.

The relation between the intracellular glutathione (GSH) concentration and hydrogen-peroxide(H2O2)-induced cytotoxicity was investigated. The intracellular GSH concentration in human glioblastoma (T98G, U87MG) and glioma (KG1C) cell lines was one or two orders of magnitude higher than that in a human myelogenous leukemic cell line (HL-60), which showed higher sensitivity to H2O2. Pretreatment of these cell lines with L-buthionine-[S,R]-sulfoximine, which significantly reduced the intracellular GSH concentration, increased their sensitivity against H2O2, whereas pretreatment with N-acetyl-L-cysteine, which did not significantly change the intracellular GSH concentration, only marginally protected the cells from the cytotoxic effect of H2O2. The results suggest that drug sensitivity of tumor cells can be modified by glutathione-modulating compounds.

Acetylcysteine↗
PubMed1997

Effect on an iron-chelator on ascorbate-induced cytotoxicity.

We investigated the effect of deferoxamine mesylate (DFO), an iron chelator, to test whether ascorbate-induced cytotoxicity is due to iron-catalyzed oxidation. Exposing human promyelocytic leukemic HL-60 cells to either sodium ascorbate or ascorbic acid for 1 h resulted in the progressive production of apoptotic cells characterized by cell shrinkage, as well as nuclear and internucleosomal DNA fragmentation. The addition of micromolar to millimolar concentrations of DFO during the 1-h exposure did not inhibit, but rather enhanced the ascorbate-induced apoptosis in both regular and serum-free RPMI1640 medium. However, a higher concentration of serum significantly inhibited the ascorbate-induced cytotoxicity. In contrast, the cytotoxic activity of ascorbate against T98G human glioblastoma cells was enhanced or reduced by micromolar and millimolar concentrations of DFO, respectively. Ascorbate significantly increased the oxidation potential in the culture medium, and the pro-oxidant action of ascorbate was further augmented by the presence of the cells. DFO did not significantly affect the ascorbyl radical intensity and only slightly reduced the ascorbate-elevated oxidation potential. These data demonstrated that ascorbate can induce cytotoxicity even in iron-deficient medium.

Apoptosis↗
PubMed1997

Induction of apoptosis in human eosinophilic leukemic cell line (EOL-1).

Exposure of human eosinophilic leukemic EOL-1 cells to H2O2, ascorbic acid derivatives, actinomycin D, low-molecular-weight polyphenols, UV irradiation, or hyperthermia resulted in nuclear fragmentation, but failed to induce internucleosomal DNA cleavage. The findings suggest that internucleosomal DNA fragmentation is not a universal biochemical hallmark of apoptosis. Removal of Ca2+ ions from the culture medium significantly reduced the cytotoxic activity of sodium ascorbate, but not that of H2O2. H2O2 significantly elevated the intracellular Ca2+ concentration, with or without Ca2+ in the culture medium. This suggests that sodium ascorbate and H2O2 initiate cell death by different mechanisms. Induction of apoptosis in in vitro systems might be useful in studying the pathogenesis of allergy or asthma.

Apoptosis↗
PubMed1997

[A study of the indication for conservative surgery in adult hydronephrosis based on presurgery post-contrast computed tomography (CT) finding].

BACKGROUND AND OBJECT: The cases with adult hydronephrosis are usually performed either conservative surgery or nephrectomy according to the grade of residual renal function. The residual renal function of adult hydronephrosis are usually suspected with analysis of concentration and/or clearance of the renal urine content after percutaneous nephrostomy. However, percutaneous nephrostomy is invasive and risky. On the other hand, post-contrast computed tomography (CT) is non-invasive. We studied whether post-contrast CT is available for the assessment of residual renal function of adult hydronephrosis and also studied the indication for conservative surgery of adult hydronephrosis on post-contrast CT. MATERIALS AND METHODS: Conservative surgery or nephrectomy was performed in 14 patients with adult hydronephrosis in the duration from April, 1986 to March, 1995. All of 14 patients (14 kidneys) hydronephrosis were retrospectively studied of the character in the indication for conservative surgery by post-contrast CT before surgery. RESULTS: The indication for conservative surgery of adult hydronephrosis on post-contrast CT are (1) well enhanced renal parenchyma exist round the kidney, even if it is very thin, and (2) excretion of contrast medium to renal calyx are showed. CONCLUSION: It was concluded that post-contrast CT might be useful for the assessment of residual renal function of adult hydronephrosis.

Adolescent↗
PubMed1996

Differentiation-dependent enhanced expression of protein phosphatase 2Cbeta in germ cells of mouse seminiferous tubules.

The presence of five distinct isoforms of protein phosphatase 2Cbeta (PP2Cbeta-1 approximately -5) is known. In this study, we demonstrate that the mRNA levels of PP2Cbeta-3, -4 and -5 and PP2Cbeta protein level increased during the course of the first wave of spermatogenesis in neonatal mouse testis. Northern blot and in situ hybridization analyses revealed that PP2Cbeta-3, -4 and -5 were expressed predominantly in pachytene spermatocytes and in more highly differentiated germ cells. The substrate specificity of PP2Cbeta-4 determined with artificial substrates differed from those of PP2Cbeta-3 and -5, suggesting that the difference in the structure of PP2Cbeta-3, -4 and -5 reflect their unique physiological functions in testicular germ cells.

Animals↗
PubMed1996

Ca2+/calmodulin-dependent protein kinase type IV in dorsal root ganglion: colocalization with peptides, axonal transport and effect of axotomy.

Using the indirect immunofluorescence technique, the distribution of Ca2+/calmodulin-dependent protein kinase IV (CaM kinase IV) was studied in dorsal root ganglia (DRGs) and the sciatic nerve under normal circumstances and after axotomy and nerve ligation. CaM kinase IV-like immunoreactivity (-LI) was observed mainly in small DRG neurons but also in some large ones with the immunoreactivity mainly confined to the cell nuclei and with varying levels in the cytoplasm. CaM kinase IV-LI was present in around 1/4 of all CGRP-positive neurons and in the vast majority of the somatostatin-positive neurons. The enzyme levels decreased markedly after axotomy. The enzyme was also observed in axons in the sciatic nerve and accumulated both proximal and distal to a ligation. The present results suggest that CaM kinase is not of direct importance for upregulation of neuropeptides in DRG neurons after nerve injury. In addition to a nuclear function it may also play a role in the peripheral processes of DRG neurons.

Animals↗
PubMed1996

Immunohistochemical localization of Ca2+/calmodulin-dependent protein kinase type IV in the mature and developing rat retina.

The localization of Ca2+/calmodulin-dependent protein kinase IV (CaM kinase IV) in the mature and developing rat retina was examined by immunohistochemistry and in situ hybridization histochemistry. In immunoblotting analysis, a single band of 63 kDa was detected in the crude homogenate of the adult rat retina, indicating the presence of the alpha polypeptide of CaM kinase IV. In the adult rat retina, most of the bipolar cells and some ganglion cells exhibited CaM kinase IV-immunoreactivity. By immunoelectron microscopy, the immunoreactive product was predominantly localized to the nucleus of immunoreactive cells. In the developing rat retina, immunoreactive bipolar cells were first detected on postnatal day 10 (P10), and they were abundant on P14. All these findings suggest that CaM kinase IV may participate in some yet unknown nuclear Ca(2+)-relating visual signal-processing of the retina.

Animals↗
PubMed1996

Localization of mRNA for Ca2+/calmodulin-dependent protein kinase I in the brain of developing and mature rats.

The gene expression of Ca2+/calmodulin-dependent protein kinase I (CaM kinase I) in the brain of developing and adult rats was examined by in situ hybridization histochemistry. During the development, CaM kinase I showed two chronological expression patterns; the persistent and relative high expression as observed in the olfactory bulb and cerebellar cortex, and the gradual decrease in the expression during the postnatal development as observed in most other brain regions. The gene expression was not detected in the germinal ventricular zone and cerebellar external granular layer. In the mature brain, CaM kinase I mRNA was expressed widely, though weakly in general, in almost all neurons, except for the olfactory bulb, cerebellum and hippocampus expressing at high intensity. These findings suggest that CaM kinase I may play a variety of neuronal Ca2+/calmodulin-mediated signaling processes in the developing and mature brains.

Animals↗
PubMed1996

The requirement for and mobilization of calcium during induction by sodium ascorbate and by hydrogen peroxide of cell death.

The requirement for and mobilization of Ca2+ ions during induction of cell death by sodium ascorbate were compared with those during induction of cell death by hydrogen peroxide. When HL-60 cells were incubated with sodium ascorbate, a rapid increase in the intracellular concentration of Ca2+ ions and subsequent apoptotic cell death, characterized by cell shrinkage, nuclear fragmentation and cleavage of internucleosomal DNA to yield fragments that were multiples of 180-200 base pairs, were induced. However, these effects of sodium ascorbate were significantly reduced in Ca2+-depleted medium. By contrast, hydrogen peroxide induced similar apoptosis associated phenomena in the presence and in the absence of extracellular Ca2+ ions. The intracellular concentration of the reduced form of glutathione was not significantly affected and glutathione disulfide was undetectable during the early stages of apoptosis. These data suggest that sodium ascorbate and hydrogen peroxide initiate cell death by different mechanisms.

Apoptosis↗
PubMed1996

Enhanced gene expression for phosphatidylinositol 3-kinase in the hypoglossal motoneurons following axonal crush.

We attempted to see whether or not gene expression of phosphatidylinositol 3-kinase (PI 3-kinase) is changeable in the hypoglossal nucleus of rats after hypoglossal nerve crushing by in situ hybridization histochemistry. After unilateral nerve crushing, an apparent enhancement of gene expression for PI 3-kinase was observed in individual neurons of the hypoglossal nucleus at the operated side on the first postoperative day, and it was sustained for 7 postoperative days. Thereafter the expression decreased at the operated side and no significant difference in the expression level was noticed between the operated nucleus and the contralateral, non-operated or sham-operated nucleus on postoperative day 14. The present study suggests that PI 3-kinase contributes to some important roles in morphological changes of mature neurons associated with nerve regeneration.

Animals↗
PubMed1996

Dopamine D2 receptor plays a critical role in cell proliferation and proopiomelanocortin expression in the pituitary.

BACKGROUND: It has been suggested that the dopaminergic system is involved in the inhibitory control of secretion of pituitary hormones and in the regulation of motor function in the striatum. To elucidate the specific role of the dopamine D2 receptor (D2R) in the pituitary and brain, we generated D2R deficient (D2R mutant) mice using the gene targeting method. RESULTS: Electrophysiological studies as well as ligand binding assays show no functional D2R in mutant mice. The D2R mutant mice display a hypoactivity and a slow, creeping movement. The expression of enkephalin mRNA in the striatum is increased in the mutant mice, but not that of dynorphin and substance P. D2R mutant mice have significantly darker coat colour than their wild-type littermates and show an elevation of plasma alpha-melanocyte stimulating hormone (alpha-MSH) levels. We found corresponding hyperplastic changes of intermediate lobe of the pituitary and the increased expression of pro opiomelanocortin (POMC) in the pituitary in D2R mutant mice. CONCLUSIONS: D2R plays a critical role in the inhibitory regulation of endocrine cell proliferation and the transcription of POMC mRNA, and consequently in the regulation of alpha-MSH in plasma. D2R might be involved in the regulation of enkephalin expression in the striatum, and hence might affect the movement and the behaviour.

Animals↗
PubMed1996

Clinicopathological evaluation of repeated courses of intravesical bacillus Calmette-Guerin instillation for preventing recurrence of initially resistant superficial bladder cancer.

PURPOSE: The efficacy of repeated courses of intravesical bacillus Calmette-Guerin (BCG) for superficial bladder cancer was assessed with particular attention to initially resistant cases. MATERIALS AND METHODS: A total of 75 patients with stages Ta to T1b superficial transitional cell bladder carcinoma received 6 weekly instillations of 80 mg. Tokyo strain BCG in 40 ml. saline followed by 6 instillations at monthly intervals. If tumors recurred, another course of treatment was given with surgery. RESULTS: Of 17 patients (22.7%) with recurrent tumor at followup periods of up to 84 months 12 received an additional course of BCG instillations according to the same protocol after transurethral resection of bladder tumors, and 10 (83.3%) showed no further recurrence with or without additional surgery and BCG therapy after a median followup of 42.9 months. Thus, the overall success rate with this approach was 90.7% (68 of 75 patients). Comparison of patients with and without recurrence revealed a significant difference in number of tumors before therapy (p < 0.05), and a pronounced tendency (p = 0.00507) for recurrence after prior systemic chemotherapy or intravesical instillation. CONCLUSIONS: The results suggest that up to 3 courses of repeated intravesical instillation of BCG are effective even for cases that initially did not respond, and that best results may be achieved if no other prior chemotherapy has been attempted.

Administration, Intravesical↗
PubMed1996

[Clinical analysis of 683 prostatic cancer patients in the Tokai Urological Cancer Registry].

Of 815 patients with prostatic carcinoma registered in Tokai Urological Cancer Registry between 1989 and 1991, 683 patients followed up until April to July 1992 were analyzed. The patients were between 48 and 94 years old (mean 73.2). The clinical stage was A in 96 (14.1%), B in 118 (17.3%), C in 117 (17.1%) and D in 352 (51.5%) patients. The histological study well differentiated adenocarcinoma in 150 (22%) patients, moderately differentiated adenocarcinoma in 305 (44.6%), and poorly differentiated adenocarcinoma in 194 (28.4%) patients. There were 12 undifferentiated adenocarcinomas and 22 were not classified. The incidence of patients with poorly differentiated adenocarcinoma increased with the progression of clinical stage. Hormonal therapy was the main treatment (92.8%) and a variety of hormonal therapies with surgery or chemotherapy were attempted through out the clinical stages. Overall survival rate at 5 years was 48.6%. The 5-year survival rage for stage A, B, C and D carcinoma was 84.7, 93.1, 51.8 and 30.3%, respectively. Significant differences in the survival of patients were noted among stage A or B, stage C and stage D (Logrank test: p < 0.0001). The 5-year survival rate was 70.2% for well differentiated, 53.0% for moderately differentiated, and 32.6% for poorly differentiated adenocarcinoma (Logrank test: p < 0.0001). Disease-specific death was observed in 128 patients (66%), and cardio- or cerebrovascular death accounted for 16 (8%) deaths.

Adenocarcinoma↗
PubMed1996

Epidermoid cyst of the scrotum: a case report.

A 44-year-old male was admitted with the chief complaint of a huge mass in the right scrotum. Computed tomography (CT), magnetic resonance imaging (MRI) and ultrasonography demonstrated a homogeneous lesion in the right testis. Under the diagnosis of right testicular tumor, surgical resection was performed and the right testis itself was found to be essentially normal. The mass contained 500 ml of liquid. The pathologic diagnosis was an epidermoid cyst of the scrotum, a rare disease with only 11 cases reported in Japan.

Adult↗