Biomedical subjects

F Nomura

Publications and source records attributed to F Nomura.

At least 19 recordsLinked to original sources

PubMed2001

Capabilities of liposomes for topological transformation.

Dynamic behaviors of liposomes caused by interactions between liposomal membranes and surfactant were studied by direct real-time observation by using high-intensity dark-field microscopy. Solubilization of liposomes by surfactants is thought to be a catastrophic event akin to the explosion of soap bubbles in the air; however, the actual process has not been clarified. We studied this process experimentally and found that liposomes exposed to various surfactants exhibited unusual behavior, namely continuous shrinkage accompanied by intermittent quakes, release of encapsulated liposomes, opening up, and inside-out topological inversion.

Lipids↗

PubMed2001

IkappaB kinase alpha is essential for mature B cell development and function.

IkappaB kinase (IKK) alpha and beta phosphorylate IkappaB proteins and activate the transcription factor, nuclear factor (NF)-kappaB. Although both are highly homologous kinases, gene targeting experiments revealed their differential roles in vivo. IKKalpha is involved in skin and limb morphogenesis, whereas IKKbeta is essential for cytokine signaling. To elucidate in vivo roles of IKKalpha in hematopoietic cells, we have generated bone marrow chimeras by transferring control and IKKalpha-deficient fetal liver cells. The mature B cell population was decreased in IKKalpha(-/-) chimeras. IKKalpha(-/-) chimeras also exhibited a decrease of serum immunoglobulin basal level and impaired antigen-specific immune responses. Histologically, they also manifested marked disruption of germinal center formation and splenic microarchitectures that depend on mature B cells. IKKalpha(-/-) B cells not only showed impairment of survival and mitogenic responses in vitro, accompanied by decreased, although inducible, NF-kappaB activity, but also increased turnover rate in vivo. In addition, transgene expression of bcl-2 could only partially rescue impaired B cell development in IKKalpha(-/-) chimeras. Taken together, these results demonstrate that IKKalpha is critically involved in the prevention of cell death and functional development of mature B cells.

Animals↗

PubMed2001

Enhanced polyadenosine diphosphate-ribosylation in cirrhotic liver and carcinoma tissues in patients with hepatocellular carcinoma.

AIM: The aim of this study is to assess the poly ADP-ribosylation activity in human hepatocellular carcinoma (HCC) and in liver cirrhosis (LC) as compared to the activity in normal livers (NL). METHODS: Hepatocellular carcinoma and LC tissues were sampled from 19 patients with HCC. Normal liver tissue was obtained from 19 patients with metastatic liver cancer. Poly ADP-ribosylation activity of these tissues was measured by using [32P]-adenylate nicotinamide adenine dinucleotide (NAD)-incorporation into the 116-kDa protein. Nicotinamide adenine dinucleotide glycohydrolase activity of these tissues was determined with thin layer chromatography. The immunohistochemical expression of Ki-67 was also assessed as a parameter of cell proliferative activity. RESULTS: The poly ADP-ribosylation of the 116 kDa protein was significantly increased in patients with HCC and LC as compared with NL (P<0.0001, P<0.05, respectively) and was inhibited by poly (ADP-ribose) polymerase inhibitors in a dose-dependent manner. There was no significant difference in NAD glycohydrolase activity among the three groups. A significant correlation was found between the Ki-67 positive cell rate and the relative radioactivity of poly ADP-ribosylation in HCC patients (r=0.794, P<0.0001). The poly ADP-ribosylation of the 116 kDa protein of LC was significantly higher in patients who had recurrences of HCC after hepatic resection than in patients without recurrence (P<0.05). CONCLUSION: Poly ADP-ribosylation of the 116 kDa protein in HCC patients might be enhanced with its proliferative activity, and poly ADP-ribosylation of the same protein in LC patients might be a useful parameter of carcinogenic potential for predicting HCC recurrence after hepatectomy in patients who have had HCC.

Adult↗

PubMed2001

Metabolic and ethnic determinants of alcohol drinking habits and vulnerability to alcohol-related disorder.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Shoji Harada and Dharam P. Agarwal. The presentations were (1) Mutations in the exons, exon-intron junctions, and promoter regions of human CYP2E1 gene and alcoholism, by Fumio Nomura; (2) Genetic variability in alcohol metabolism and drinking habits in Japanese, by Shoji Harada; (3) Genetic studies of alcohol dependence using alcoholics with inactive ALDH2, by Susumu Higuchi; and (4) Alcohol consumption, apolipoprotein polymorphisms, and cardiovascular disorders, by Dharam P. Agarwal.

Alcohol Drinking↗

PubMed2001

Polymorphism of the 5'-flanking region of the CYP2E1 gene: an association study with alcoholism.

BACKGROUND: Recently, a restriction fragment length polymorphism in the regulatory region of the CYP2E1 gene was identified. It has been suggested that the polymorphism is associated with the elevated activity of the cytochrome P-450 2E1 (CYP2E1) enzyme in obese or alcoholic subjects. However, significance of the polymorphism in connection with alcoholism has not been studied. In the present study, we have characterized these repeated sequences in the 5'-untranslated region of the CYP2E1 gene in Japanese subjects and North American white subjects and investigated whether these polymorphisms are associated with drinking habits and alcoholism. METHODS: DNAs were isolated from blood samples of 192 Japanese nonalcoholics and 202 alcoholics as well as 125 North American white nonalcoholics. DNA samples were amplified by polymerase chain reaction and subjected to a fluorescent-based single-strand conformational change polymorphism analysis, DNA fragment analysis, and polymerase chain reaction-direct sequencing. RESULTS: Four alleles (A1-A4) were found, which were differentiated by the six subunits (L1, L2, L3, L4, S1, S2) based on the size difference and nucleotide replacement. A2 and A4 alleles were observed in the two ethnic groups (A2: Japanese subjects, 0.752; white subjects, 0.976; A4: Japanese subjects, 0.227; white subjects, 0.016). However, A1 allele was found only in North American white subjects (0.008), and A3 allele was detected only in Japanese subjects (0.021). Allele frequencies were significantly different between the two ethnic groups (p < 0.0001). Distribution of genotypes between Japanese nonalcoholics and alcoholics were not significantly different. Also, no significant difference for the allele frequencies was observed between Japanese moderate drinkers and heavy drinkers. CONCLUSIONS: Our data suggested no association among the polymorphic repeats, drinking behavior, and alcoholism. Allele frequencies were significantly different between Japanese subjects and North American white subjects.

5' Untranslated Regions↗

PubMed2001

Effects of chronic alcohol consumption on hepatic poly-ADP-ribosylation in the rat.

BACKGROUND: Poly-adenosine diphosphate (ADP)-ribosylation is involved in a variety of biological processes, which include DNA repair, malignant transformation, and apoptosis. It is of interest how this reaction is altered after long-term alcohol intake. Therefore, we determined long-term alcohol effects on hepatic poly-ADP-ribosylation in the rat. METHODS: Male Sprague Dawley(R) rats (four pairs) were pair-fed a nutritionally adequate liquid diet that contained ethanol as 36% of total energy and an isocaloric control diets for 4 weeks. Liver tissue homogenates and nuclear fractions were subjected to ADP-ribosylation with [32P]nicotinamide adenine dinucleotide. The ADP-ribosylated proteins were separated by SDS-PAGE, followed by autoradiography. Expression of poly-ADP-ribose polymerase (PARP) also was evaluated by Western blotting. RESULTS: Incubation of rat liver homogenates in ADP-ribosylation reaction mixture resulted in a radiolabeling of a 116 kDa protein, most likely auto-ribosylation of PARP. This poly-ADP-ribosylation was increased significantly (p < 0.025) after long-term alcohol intake. This alcohol effect was reproducible in nuclear fractions as well. Expression levels of PARP, however, were comparable between alcohol-fed rats and their pair-fed controls. CONCLUSION: Poly-ADP-ribosylation, an important posttranslational modification of nuclear proteins, was increased significantly after chronic alcohol consumption in the rat.

Alcoholism↗

PubMed2001

Effects of Hot shot on recovery after hypothermic ischemia in neonatal lamb heart.

BACKGROUND: Terminal warm blood cardioplegia, "Hot shot", is the method for providing an energy replenishment and/or early recovery of aerobic metabolism without electromechanical activity at initial reperfusion. The mechanism of beneficial effects of this Hot Shot is multifactorial. This study was designed to assess the effects of terminal warm blood cardioplegia by comparing with oxygenated terminal warm crystalloid cardioplegia. METHODS: In Group HS-B, n=8 (oxygenated blood; 37 degrees C, Ht: 20%, K+ 20 mEq/l, pH 7.237, PO2 219 mmHg) and in Group HS-C, n=8 (bloodless oxygenated (5% CO2+95%O2) crystalloid, 37 degrees C, K+ 20 mEq/l, pH 7.435, PO2 624 mmHg), terminal warm cardioplegia (20 ml/kg for 5 minutes) was studied in the isolated blood perfused neonatal lamb heart following 2 hr of cardioplegic ischemia. Another eight hearts served as control without any kind of terminal cardioplegia. After 60 min of reperfusion, LV function was measured. Coronary blood flow (CBF), oxygen content, and oxygen consumption (MVO2) were measured and the oxygen extraction ratio was calculated in Group HS-B and HS-C during terminal cardioplegia and/or reperfusion. Results are given as % recovery of preischemic values. RESULTS: HS-B as well as HS-C groups showed better functional recovery in maximum developed pressure (DP: 78.0+/-8.3 in HS-B vs 65.2+/-9.2%; p=0.018), maximum dp/dt (67.3+/-6.2 in HS-B, 65.3+/-7.4 in HS-C vs 55.8+/-5.0%; p=0.003, p=0.02), DP V10 (87.1+/-8.5 in HS-B vs 67.2+/-9.9%; p=0.0001), and peak dp/dt V10 (76.4+/-7.6 in HS-B, 69.8+/-8.1 in HS-C vs 58.6+/-6.9 %; p=0.0001) than the control group. Between the HS-B and HS-C groups, HS-B showed better functional recovery in terms of DP V10 (p=0.01). Oxygen delivery of terminal cardioplegia was almost four times higher in HS-B group (90.4+/-17.7 vs 18.7+/-1.1 mcl/ml), contrarily, HS-C group showed four times higher oxygen extraction ratio compared to HS-B group (0.78+/-0.06 vs 0.18+/-0.11), thus oxygen consumption during hot shot was maintained at the same level in both groups. CBF in the control group was lower than that in the other groups at 60 min of reperfusion. CONCLUSIONS: Reperfusion with both terminal warm cardioplegia including blood and oxygenated crystalloid cardioplegia resulted in better recovery of function and higher levels of CBF with slightly better function in terminal warm blood cardioplegia.

Animals↗

PubMed2001

[A nutritional investigation of homeless patients with tuberculosis].

A retrospective case-control study was performed with TB patients who were admitted to our hospital over the two years from Jan. 1997 to Dec. 1998 and healthy men who underwent a health screening in April 2000 in the same hospital. Thirty-two non-homeless TB patients (the first control group) and 32 healthy men (the second control group) were matched with 32 homeless TB patients according to age. All 3 groups were male. Total protein, albumin, cholesterol, cholinesterase, hemoglobin level and lymphocyte count on admission were significantly lower in the homeless patients than in the non-homeless patients and healthy men. Albumin, cholesterol, cholinesterase, hemoglobin level, white blood cell count and lymphocyte count on admission were significantly lower in non-homeless patients than healthy men. Height, weight and body mass index were significantly lower in the homeless patients than in the healthy men. However, there were no significant differences in these body characteristics between the homeless and non-homeless patients. Twenty-five percent of homeless patients died during hospitalization, compared with 6.3 percent of non-homeless patients. Lymphocyte counts among homeless patients who died during hospitalization were significantly lower than among those who survived during hospitalization. Total protein, albumin, cholesterol, cholinesterase, hemoglobin level and weight were lower in patients who died than in those who survived, although the differences were statistically not significant.

Adult↗

PubMed2000

Synergy and cross-tolerance between toll-like receptor (TLR) 2- and TLR4-mediated signaling pathways.

A family of Toll-like receptor (TLR) mediates the cellular response to bacterial cell wall components; murine TLR2 and TLR4 recognize mycoplasmal lipopeptides (macrophage-activating lipopeptides, 2 kDa (MALP-2)) and LPS, respectively. Costimulation of mouse peritoneal macrophages with MALP-2 and LPS results in a marked increase in TNF-alpha production, showing the synergy between TLR2- and TLR4-mediated signaling pathways. Macrophages pretreated with LPS show hyporesponsiveness to the second LPS stimulation, termed LPS tolerance. The LPS tolerance has recently been shown to be primarily due to the down-regulation of surface expression of the TLR4-MD2 complex. When macrophages were treated with MALP-2, the cells showed hyporesponsiveness to the second MALP-2 stimulation, like LPS tolerance. Furthermore, macrophages pretreated with MALP-2 showed reduced production of TNF-alpha in response to LPS. LPS-induced activation of both NF-kappaB and c-Jun NH(2)-terminal kinase was severely impaired in MALP-2-pretreated cells. However, MALP-2-pretreated macrophages did not show any reduction in surface expression of the TLR4-MD2 complex. These findings indicate that LPS-induced LPS tolerance mainly occurs through the down-regulation of surface expression of the TLR4-MD2 complex; in contrast, MALP-2-induced LPS tolerance is due to modulation of the downstream cytoplasmic signaling pathways.

Animals↗

PubMed2000

Effects of natriuretic peptides (ANP, BNP, CNP) on catecholamine synthesis and TH mRNA levels in PC12 cells.

Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) are present in adrenal chromaffin cells, and are co-secreted with catecholamines suggesting that these natriuretic peptides (NPs) may modulate functions of chromaffin cells in an autocrine and/or paracrine manner. Therefore, we investigated the effects of NPs on tyrosine hydroxylase (TH: a rate-limiting enzyme in biosynthesis of catecholamine) mRNA in rat pheochromocytoma PC12 cells. It was also determined whether the cyclic GMP/cGMP-dependent protein kinase (cGMP/PKG) pathway was involved in theses effects. Finally, we examined the effects of NPs on intracellular catecholamine content to confirm increase of catecholamine synthesis following TH mRNA induction. NPs (0.1 microM) induced significant increases of the TH mRNA (ANP= BNP> CNP). Also, the effects of NPs on TH mRNA were mimicked by 8-bromo cyclic GMP (1mM), and were blocked by KT5823 (1 microM) (inhibitor PKG) or LY83583 (1 microM) (guanylate cyclase inhibitor). Moreover, NPs were shown to induce significant increases of intracellular catecholamine contents (ANP= BNP> CNP). These findings suggest that NPs induced increases of TH mRNA through cGMP/PKG dependent mechanisms, which, in turn, resulted in stimulation of catecholamine synthesis in PC12 cells.

Animals↗

PubMed2000

Cutting edge: endotoxin tolerance in mouse peritoneal macrophages correlates with down-regulation of surface toll-like receptor 4 expression.

Monocytes/macrophages exposed to LPS show reduced responses to second stimulation with LPS, which is termed LPS tolerance. In this study, we investigated molecular mechanism of LPS tolerance in macrophages. Mouse peritoneal macrophages pre-exposed to LPS exhibited reduced production of inflammatory cytokines in a time- and dose-dependent manner. Activation of neither IL-1 receptor-associated kinase nor NF-kappaB was observed in macrophages that became tolerant by LPS pretreatment, indicating that the proximal event in Toll-like receptor 4 (TLR4)-MyD88-dependent signaling is affected in tolerant macrophages. Although TLR4 mRNA expression significantly decreased within a few hours of LPS pretreatment and returned to the original level at 24 h, the surface TLR4 expression began to decrease within 1 h, with a gradual decrease after that, and remained suppressed over 24 h. A decrease in inflammatory cytokine production in tolerant macrophages well correlates with down-regulation of the surface TLR4 expression, which may explain one of the mechanisms for LPS tolerance.

Animals↗

PubMed2000

Reliable and cost-effective system for surgical stent graft insertion.

For intraoperative stented graft implantation, we use a half-inch translucent soft polyvinyl tube as a sheath and an obturator from a two-stage venous cannula as a pushing rod. Ten centimeters of any kind of graft can be used for the stent graft itself. The stent we used was a self-expandable Gianturco double Z stent and was sutured inside the graft.

Aortic Dissection↗

PubMed2000

NF-kappaB activation through IKK-i-dependent I-TRAF/TANK phosphorylation.

BACKGROUND: NF-kappaB is an ubiquitously expressed transcription factor that plays an important role in the immune, anti-apoptotic and inflammatory responses. NF-kappaB is normally sequestered in the cytoplasm by interacting with inhibitory IkappaB molecules. Upon stimulation, IkappaB is phosphorylated and subsequently degraded by the proteasome, allowing NF-kappaB to translocate into the nucleus where they regulate target gene expression. Two kinases, IKK-alpha and IKK-beta, which are responsible for IkappaB phosphorylation were recently identified. We have recently identified a cytokine inducible IKK-i, a kinase related to IKK-alpha and -beta. IKK-i significantly induced NF-kappaB activation upon over-expression, as did IKK-alpha and IKK-beta. Unlike IKK-alpha and IKK-beta, IKK-i phosphorylated Ser36 but not Ser32 in vitro, suggesting that IKK-i activates NF-kappaB by distinct mechanisms from the conventional IKKs. RESULTS: I-TRAF/TANK was isolated as a molecule that interacts specifically with inducible IkappaB kinase (IKK-i) by the yeast two-hybrid screening procedure. The association of IKK-i and I-TRAF is mediated via the interaction between the N-terminal domain of I-TRAF and the C-terminal portion of IKK-i. In vitro kinase assays demonstrate that IKK-i phosphorylates I-TRAF in the middle portion that associates with TRAF2. Interestingly, TRAF2 is freed from the I-TRAF/TRAF2 complex after I-TRAF phosphorylation. NF-kappaB activation by IKK-i is significantly blocked by coexpression of the N-terminal domain of I-TRAF, dominant negative TRAF2, and dominant negative NIK and IKK-beta. IKK-i over-expression also induced c-Jun N-terminal kinase. These results show that I-TRAF is a substrate of IKK-i. NF-kappaB activation by IKK-i may be mediated through phosphorylation of I-TRAF by IKK-i and subsequent liberation of TRAF2. CONCLUSION: These results indicate that NF-kappaB activation by IKK-i is mediated through phosphorylation of I-TRAF/TANK by IKK-i and subsequent liberation of TRAF2.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Enhancement of poly-adenosine diphosphate-ribosylation in human hepatocellular carcinoma.

BACKGROUND: Poly-adenosine diphosphate (ADP)-ribosylation, catalysed by poly(ADP-ribose) polymerase (PARP), is a post-translational modification of nuclear proteins and is involved in a wide range of biological processes including DNA repair, cell proliferation and malignant transformation. Alteration of this reaction in human hepatocellular carcinoma (HCC) is of interest, but has not yet been explored. The aim of this study was to evaluate poly-ADP-ribosylation and to compare the expression of PARP in HCC and adjacent non-tumour tissues. METHODS: Tumorous and adjacent non-tumorous tissues were obtained from five consecutive patients with HCC during surgery for tumour resection. Tissue homogenates were subjected to ADP-ribosylation with [32P]-nicotinamide adenine dinucleotide. The ADP-ribosylated proteins were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis, followed by autoradiography. Expression of PARP was also evaluated by western blotting. RESULTS: Several proteins were ADP-ribosylated in human HCC tissues. Notably, the radiolabelling of a 116-kDa protein was remarkably greater than that in adjacent non-tumorous tissues (86.5 +/- 35.2 arbitrary units by densitometry vs 12.2 +/- 9.9, mean +/- SD, n = 5, P < 0.02). The radiolabelling of the 116-kDa protein was decreased in the presence of PARP inhibitors in a concentration-dependent manner. Immunoblot analyses revealed that the radiolabelled protein was PARP and that its expression was significantly greater in HCC than in adjacent non-tumorous tissues (333 +/- 204% of non-tumorous tissue, P < 0.05). CONCLUSIONS: We found that poly-ADP-ribosylation and PARP expression were significantly increased in human HCC compared with those in adjacent non-tumorous tissues in surgically obtained specimens.

ADP-Ribosylation Factors↗

PubMed2000

Enhanced expression of mRNA coding for the adrenaline-synthesizing enzyme phenylethanolamine-N-methyl transferase in adrenaline-secreting pheochromocytomas.

PURPOSE: In some pheochromocytomas, the tumors contain and secrete greater amounts of adrenaline than do normal adrenal medullas. It is not yet known how adrenaline synthesis is enhanced in the adrenaline-secreting pheochromocytomas. MATERIALS AND METHODS: As a first step toward understanding the molecular mechanisms by which adrenaline synthesis is controlled in these tumors, we measured the level of mRNA coding for the adrenaline-synthesizing enzyme phenylethanolamine N-methyl transferase (PNMT) and the content of adrenaline in the pheochromocytomas (n = 9), including 3 cases of the adrenaline-secreting type (one of the patients had bilateral pheochromocytomas), and in normal adrenal medullas (n = 7). We then measured the concentration of cortisol, which is thought to regulate the PNMT activity. Finally, we examined the expression of the mRNA for Egr-1, which was recently reported to be a transcriptional factor regulating PNMT gene expression. RESULTS: In the 4 tissue specimens from 3 adrenaline-secreting pheochromocytomas, the contents of adrenaline and the PNMT mRNA expression were considerably greater than those of the normal adrenal medullas. PNMT immunoreactivity was only detected in the adrenaline-secreting tumors. Three of the 4 specimens showed high concentrations of cortisol. To show the capacity for cortisol production locally in the pheochromocytoma tissues, we showed the expression of a glucocorticoid biosynthetic enzyme, 17alpha-hydroxylase, in the tumors by Western blotting. PNMT expression was found to be associated with 17alpha-hydroxylase expression in the tumors. The glucocorticoid receptor expression was also correlated with PNMT expression in the tumors and the expression of Egr-1 was also high in 3 of the 4 specimens. CONCLUSIONS: These findings indicate that adrenaline production in adrenaline-secreting pheochromocytomas is primarily controlled by the level of PNMT gene expression, and that the gene expression may be enhanced by both cortisol and Egr-1.

Adrenal Gland Neoplasms↗

PubMed2000

Biological markers of alcoholism with respect to genotypes of low-Km aldehyde dehydrogenase (ALDH2) in Japanese subjects.

BACKGROUND: Although the mutant low-Km acetaldehyde dehydrogenase (ALDH2) allele (ALDH2(2)) with reduced capacity to metabolize acetaldehyde offers biological protection against alcoholism and subsequent alcohol-induced organ damage in many individuals, a significant proportion of individuals with heterozygote of the normal and mutant ALDH2 gene (ALDH2(1)/2(2)) consume excessive amounts of alcohol. Indeed, it has been postulated that habitual drinkers with ALDH2(1)/2(2) may be at a higher risk for alcoholic liver disease than those with ALDH2(1)/2(1). In this study, we determined how representative biological markers of alcoholism (gamma-glutamyltransferase [GGT], carbohydrate-deficient transferrin [CDT], and the mean corpuscular volume of erythrocytes [MCV]) differ with respect to the ALDH2 genotypes in Japanese habitual drinkers. METHODS: We obtained genomic DNA samples from 227 Japanese men with various drinking habits. ALDH2 genotypes were determined by allele-specific polymerase chain reaction. GGT, CDT, and MCV were determined and compared between ALDH2(1)/2(1) and ALDH2(1)/2(2) habitual drinkers who consumed more than 66 g of alcohol per day for more than 5 years. We measured CDT by anion-exchange chromatography followed by turbidity immunoassay by using a commercially available assay kit (Axis %CDT TIA). RESULTS: CDT levels were comparable between the two groups. GGT activities were significantly greater in ALDH2(1)/2(1) than in ALDH2(1)/2(2) habitual drinkers (81 +/- 85 vs. 53 +/- 40 IU/liters, p < 0.02). MCV values, on the other hand, were significantly larger in ALDH2(1)/2(2) than in ALDH2(1)/2(1) subjects (98.2 +/- 5.8 vs. 95.8 +/- 4.2 fl, p = 0.02). When we used elevation of either CDT or GGT to detect habitual drinking in ALDH2(1)/2(1) and 2(1)/2(2) subjects, the sensitivities were 57% and 46%, respectively. CDT levels were similar between habitual drinkers with normal aspartate aminotransferase levels and those with elevated levels. CONCLUSION: GGT and MCV, but not CDT, differ with respect to the ALDH2 genotypes in Japanese male habitual drinkers. ALDH2 genotypes should be considered when interpreting data on biological markers of alcoholism.

Adult↗

PubMed1999

Leptin directly stimulates catecholamine secretion and synthesis in cultured porcine adrenal medullary chromaffin cells.

Leptin, a protein encoded by the ob gene, is an adipose tissue-derived signaling factor involved in body weight homeostasis. The hypothalamus is a major site of central action for leptin. However, mounting evidence indicates expression of leptin receptor mRNA in various peripheral organs including the adrenal medulla. Therefore, we investigated the effects of leptin on catecholamine secretion and synthesis in cultured porcine adrenal medullary chromaffin cells. We initially confirmed the expression of leptin receptor (Ob-Rb) mRNA in cultured porcine adrenal medullary cells. Murine recombinant leptin (>==50 nM) strongly induced the release of both epinephrine (E) and norepinephrine (NE) from chromaffin cells. Removal of external Ca(2+) significantly suppressed these effects. Also, leptin (>==1 nM) enhanced nicotine-induced increases in E- and NE. Leptin (1, 10, 100 nM) significantly increased tyrosine hydroxylase (TH) (a rate-limiting enzyme in the biosynthesis of catecholamine) mRNA levels in a concentration-dependent manner. Furthermore, leptin (1, 10, 100 nM) significantly induced increases in cAMP levels, suggesting that the stimulatory effects on TH mRNA are mediated, at least in part, by the cAMP/protein kinase A pathway. These results indicate that leptin directly stimulates catecholamine release and synthesis, which in turn may potentiate the anti-obesity effects of leptin.

Animals↗

PubMed1999

Death-associated protein kinase 2 is a new calcium/calmodulin-dependent protein kinase that signals apoptosis through its catalytic activity.

We have identified and characterized a new calcium/calmodulin (Ca2+/CaM) dependent protein kinase termed death-associated protein kinase 2 (DAPK2) that contains an N-terminal protein kinase domain followed by a conserved CaM-binding domain with significant homologies to those of DAP kinase, a protein kinase involved in apoptosis. DAPK2 mRNA is expressed abundantly in heart, lung and skeletal muscle. The mapping results indicated that DAPK2 is located in the central region of mouse chromosome 9. In vitro kinase assay revealed that DAPK2 is autophosphorylated and phosphorylates myosin light chain (MLC) as an exogenous substrate. DAPK2 binds directly to CaM and is activated in a Ca2+/CaM-dependent manner. A constitutively active DAPK2 mutant is generated by removal of the CaM-binding domain (deltaCaM). Treatment of agonists that elevate intracellular Ca2+-concentration led to the activation of DAPK2 and transfection studies revealed that DAPK2 is localized in the cytoplasm. Overexpression of DAPK2, but not the kinase negative mutant, significantly induced the morphological changes characteristic of apoptosis. These results indicate that DAPK2 is an additional member of DAP kinase family involved in apoptotic signaling.

3T3 Cells↗