永井 良三

Adiponectin is an adipocyte-derived hormone, which has been shown to play important roles in the regulation of glucose and lipid metabolism. Eight mutations in human adiponectin have been reported, some of which were significantly related to diabetes and hypoadiponectinemia, but the molecular mechanisms of decreased plasma levels and impaired action of adiponectin mutants were not clarified. Adiponectin structurally belongs to the complement 1q family and is known to form a characteristic homomultimer. Herein, we demonstrated that simple SDS-PAGE under non-reducing and non-heat-denaturing conditions clearly separates multimer species of adiponectin. Adiponectin in human or mouse serum and adiponectin expressed in NIH-3T3 or Escherichia coli formed a wide range of multimers from trimers to high molecular weight (HMW) multimers. A disulfide bond through an amino-terminal cysteine was required for the formation of multimers larger than a trimer. An amino-terminal Cys-Ser mutation, which could not form multimers larger than a trimer, abrogated the effect of adiponectin on the AMP-activated protein kinase pathway in hepatocytes. Among human adiponectin mutations, G84R and G90S mutants, which are associated with diabetes and hypoadiponectinemia, did not form HMW multimers. R112C and I164T mutants, which are associated with hypoadiponectinemia, did not assemble into trimers, resulting in impaired secretion from the cell. These data suggested impaired multimerization and/or the consequent impaired secretion to be among the causes of a diabetic phenotype or hypoadiponectinemia in subjects having these mutations. In conclusion, not only total concentrations, but also multimer distribution should always be considered in the interpretation of plasma adiponectin levels in health as well as various disease states.

Skeletal muscle glucose utilization (SMGU) can be measured by dynamic PET imaging with F-18-FDG to characterize insulin resistance. The aim of this study was to determine the validity of simple methods to quantify SMGU by static PET imaging. Methods: Ten patients underwent dynamic F-18-FDG PET of the femoral region during hyperinsulinemic euglycemic clamping. SMGU was determined by Patlak graphical analysis using data from dynamic imaging with frequent arterial blood sampling. Standardized uptake values (SUVs) were calculated at 45 and 55 min after tracer injection. Skeletal muscle-to-background ratio (SM/B ratio), tissue count divided by venous plasma activity, was also computed at 45 and 55 min. These simple indices were compared by linear regression with the SMGU measured as above, and an estimated SMGU was obtained using the regression equation thus generated, together with a simple index. Results: SMGU was highly correlated with SUVs (r = 0.941 at 45 min, r = 0.951 at 55 min) and SM/B ratios (r = 0.968 at 45 min, r = 0.984 at 55 min). Although SMGU was almost proportional to SM/B ratios, the y-intercepts of the regression lines for SUVs significantly differed from zero. The residual in estimating SMGU using the regression equation was marginally smaller for SM/B ratios than for SUVs and for indices at 55 min than at 45 min, but these differences did not reach statistical significance. Correction for plasma glucose level slightly elevated the correlation coefficients between SMGU and these simple indices. Conclusion: It is proposed that the simple quantitative indices, SUV and the SM/B ratio, are reliable indicators of SMGU during hyperinsulinemic euglycemic clamping. Static imaging with or without a single venous blood sampling may therefore be able to replace dynamic imaging with frequent arterial blood sampling, offering substantially greater convenience in evaluating insulin resistance.

BACKGROUND: Clinical profiles and outcomes of patients with acute type B aortic dissection have not been evaluated in the current era. METHODS AND RESULTS: Accordingly, we analyzed 384 patients (65+/-13 years, males 71%) with acute type B aortic dissection enrolled in the International Registry of Acute Aortic Dissection (IRAD). A majority of patients had hypertension and presented with acute chest/back pain. Only one-half showed abnormal findings on chest radiograph, and almost all patients had computerized tomography (CT), transesophageal echocardiography, magnetic resonance imaging (MRI), and/or aortogram to confirm the diagnosis. In-hospital mortality was 13% with most deaths occurring within the first week. Factors associated with increased in-hospital mortality on univariate analysis were hypotension/shock, widened mediastinum, periaortic hematoma, excessively dilated aorta (>or=6 cm), in-hospital complications of coma/altered consciousness, mesenteric/limb ischemia, acute renal failure, and surgical management (all P<0.05). A risk prediction model with control for age and gender showed hypotension/shock (odds ratio [OR] 23.8, P<0.0001), absence of chest/back pain on presentation (OR 3.5, P=0.01), and branch vessel involvement (OR 2.9, P=0.02), collectively named 'the deadly triad' to be independent predictors of in-hospital death. CONCLUSIONS: Our study provides insight into current-day profiles and outcomes of acute type B aortic dissection. Factors associated with increased in-hospital mortality ("the deadly triad") should be identified and taken into consideration for risk stratification and decision-making.

Adrenomedullin (AM) is a potent vasodilating and natriuretic peptide that is thought to play important roles in cardiovascular function. Whether or not AM is involved in the development of cardiac hypertrophy and renal damage remains controversial. In the present study, using heterozygote knockout mice of the AM gene (AM +/-), we analyzed the physiological and pathological roles of the endogenous AM gene. There were no differences in body size or heart and kidney weight compared with wild-type (AM +/+) mice. However, angiotensin II (Ang II) infusion resulted in more severe cardiac hypertrophy in AM +/- mice. The increases in the heart weight-to-body weight ratio and wall thickness of the left ventricle were more prominent in the AM +/- mice. Renal dysfunction characterized by decreased creatinine clearance (C(cr)) was more severe in AM +/- after Ang II infusion. These results suggest that AM plays critical roles in the defense mechanism against cardiac hypertrophy and renal dysfunction. An improved understanding of these roles may pave the way to a novel pharmacological approach for the prevention of cardiovascular diseases.

Administration of angiotensin H to rats decreases renal expression of klotho, an aging-related gene, and also causes abnormal iron deposition in renal cells. Here we have examined the effects of iron overload and iron chelation on renal expression of klotho in untreated rats and rats treated with angiotensin II. Administration of iron-dextran caused a downregulation of klotho expression, and iron chelation suppressed the angiotensin II-induced downregulation of this gene. In addition, a free radical scavenger (T-0970), which effectively decreased plasma levels of 8-epi-prostaglandin F(2alpha) (8-epi-GF(2alpha)), suppressed angiotensin II-induced downregulation of klotho. Collectively, these findings suggest that abnormal iron metabolism and increased oxidative stress are involved in the mechanism of angiotensin II-mediated modulation of klotho expression. (C) 2003 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

OBJECTIVE: It has been suggested that deregulated expression of the tumor suppressor protein p53 may play a role in the pathogenesis of occlusive vascular remodeling. However, the role of p53 in cell proliferation and apoptosis in vascular lesions has been controversial. METHODS AND RESULTS: We tested the potential involvement of p53-mediated molecular signaling in lesion formation using a mouse model of vascular injury that may resemble balloon angioplasty. A large wire was inserted into the femoral artery of p53+/+ and p53-/- mice. There was no significant difference in the occurrence of rapid-onset apoptosis, that is, 4 hours after injury. At 2 weeks, the number of proliferating cells in the lesion of p53-/- mice was significantly higher than that observed in p53+/+ mice. The frequency of apoptotic cells was significantly lower in p53-/- mice than in p53+/+ mice. At 4 weeks, the neointimal hyperplasia of p53-/- mice was greater than that of p53+/+ mice. There was no significant difference in the frequency of apoptosis in the lesions. CONCLUSIONS: These results indicate a crucial role of p53 in pathological vascular remodeling after mechanical injury and provide the basis for the development of new therapies targeting p53 for a prophylactic treatment of vascular diseases.

It is of paramount importance to investigate the relation between the time-dependent change in intracellular Ca2+ concentration ([Ca2+]i) (Ca2+ transients) and the mechanical activity of isolated single myocytes to understand the regulatory mechanisms of heart function. However, because of technical difficulties in performing mechanical measurements with single myocytes, the simultaneous recording of Ca2+ transients and mechanical activity has mainly been performed with multicellular cardiac preparations that give conflicting results concerning Ca2+ transients during isometric twitches and during twitches with unloaded shortening. In the present study, we coupled intracellular Ca2+ measurement optics with a force measurement system using carbon fibers to examine the relation between Ca2+ transients and the mechanical activity of rat single ventricular myocytes over a wide range of load. To minimize the possible load dependence of sarcoplasmic reticulum Ca2+ loading, contraction mode was switched at every twitch from unloaded shortening to isometric contraction. During a twitch with unloaded shortening, the Ca2+ transients exhibited a higher peak and a higher rate of decay than transients during an isometric twitch. Similarly, when we changed the contraction mode in every pair of twitches, Ca2+ transients were dependent only on the mode of contraction. Mechanical uncoupling with 2,3-butanedione monoxime abolished this dependence on the mode of contraction. Our results suggest that Ca2+ transients reflect the affinity of troponin C for Ca2+, which is influenced by the change in strain on the thin filament but not by the length change per se.

Transcription involves molecular interactions between general and regulatory transcription factors with further regulation by protein-protein interactions (e.g. transcriptional cofactors). Here we describe functional interaction between DNA-binding transcription factor and histone chaperone. Affinity purification of factors interacting with the DNA-binding domain of the transcription factor Sp1 showed Sp1 to interact with the histone chaperone TAF-I, both alpha and beta isoforms. This interaction was specific as Sp1 did not interact with another histone chaperone CIA nor did other tested DNA-binding regulatory factors (MyoD, NFkappaB, p53) interact with TAF-I. Interaction of Sp1 and TAF-I occurs both in vitro and in vivo. Interaction with TAF-I results in inhibition of DNA-binding, and also likely as a result of such, inhibition of promoter activation by Sp1. Collectively, we describe interaction between DNA-binding transcription factor and histone chaperone which results in negative regulation of the former. This novel regulatory interaction advances our understanding of the mechanisms of eukaryotic transcription through DNA-binding regulatory transcription factors by protein-protein interactions, and also shows the DNA-binding domain to mediate important regulatory interactions.

Despite recent advances in immunosuppressive therapy, accelerated coronary atherosclerosis remains a major problem in the long-term survival of cardiac transplant recipients. However, the pathogenesis of the transplant-associated atherosclerosis remains largely unknown. Here, we investigated the origin of the vascular cells that contribute to graft vasculopathy. We performed heterotopic heart transplantation using genetically modified mice that express LacZ or green fluorescent protein (GFP) ubiquitously and constitutively. At 4 weeks after transplantation, the graft coronary arteries developed neointimal hyperplasia, expressing several smooth muscle cell markers. Most of the neointimal cells were composed of recipient cells but not graft medial smooth muscle cells. We seldom detected neointimal cells that were positive for both LacZ and GFP. When we transplanted wild-type cardiac allografts into the chimeric mice whose bone marrow cells had been replaced with those of LacZ-mice or GFP-mice, we observed that most of the neointimal cells were derived from the bone marrow. These findings suggest that recipient bone marrow-derived cells contribute to the pathogenesis of graft arteriosclerosis. Spontaneous cell fusion between recipient and donor-derived cells seems to be a rare event, if it occurs at all.

The tumor suppressor p53 is a transcription factor that activates or represses its target genes after various genotoxic stresses. We have previously shown that sterol regulatory element-binding protein-1 (SREBP-1), a key transcriptional regulator of triglyceride synthesis, and the lipogenic enzymes under its control are markedly suppressed in adipocytes from genetically obese ob/ob mice. Here we demonstrate that p53 and its target genes are highly induced in adipocytes of ob/ob mice in a fed state, leading to the negative regulation of SREBP-1 and thereby lipogenic genes. In fact, disruption of p53 in ob/ob mice completely suppressed the p53-regulated genes to wild-type levels and partially restored expression of lipogenic enzymes. Consistently, reporter gene analysis showed that p53 overexpression suppressed the promoter activity of the SREBP-1c gene and its downstream genes. Thus, the activation of p53 might constitute a negative feedback loop against excess fat accumulation in adipocytes. In conclusion, we discovered a novel role of p53 in the pathophysiology of obesity.

BACKGROUND: Although TNP-470, a synthetic analog of fumagillin, may inhibit vascular intimal hyperplasia, the effects of TNP-470 on smooth muscle cell (SMC) proliferation have not been demonstrated in vivo. The aim of this study was to confirm the effect of TNP-470 on vascular SMC proliferation using a rat carotid artery balloon injury model. MATERIALS AND METHODS: Rats were treated with vehicle or with TNP-470 at low dosage (10 mg/kg), medium dosage (20 mg/kg), or high dosage (40 mg/kg). The animals received subcutaneous injections of materials three times a week from the day following balloon injury. All rats were sacrificed at 2 weeks after injury. The ratio of intimal-to-medial cross-sectional areas (I/M ratio) and the PCNA labeling index was calculated for each group. The DNA synthesis of cultured SMCs was also evaluated using [3H]thymidine incorporation assays. Smooth muscle cells were stimulated with basic fibroblast growth factor and TNP-470 (0.01-100 ng/ml) were added. RESULTS: The inhibition of intimal hyperplasia increased in a dose-dependent manner. TNP-470 also decreased PCNA expression in the neointima and inhibited DNA synthesis of cultured SMCs. CONCLUSIONS: TNP-470 may be useful in the prevention of vascular intimal hyperplasia.

Adiponectin (also known as 30-kDa adipocyte complement-related protein; Acrp30) is a hormone secreted by adipocytes that acts as an antidiabetic and anti-atherogenic adipokine. Levels of adiponectin in the blood are decreased under conditions of obesity, insulin resistance and type 2 diabetes. Administration of adiponectin causes glucose-lowering effects and ameliorates insulin resistance in mice. Conversely, adiponectin-deficient mice exhibit insulin resistance and diabetes. This insulin-sensitizing effect of adiponectin seems to be mediated by an increase in fatty-acid oxidation through activation of AMP kinase and PPAR-alpha. Here we report the cloning of complementary DNAs encoding adiponectin receptors 1 and 2 (AdipoR1 and AdipoR2) by expression cloning. AdipoR1 is abundantly expressed in skeletal muscle, whereas AdipoR2 is predominantly expressed in the liver. These two adiponectin receptors are predicted to contain seven transmembrane domains, but to be structurally and functionally distinct from G-protein-coupled receptors. Expression of AdipoR1/R2 or suppression of AdipoR1/R2 expression by small-interfering RNA supports our conclusion that they serve as receptors for globular and full-length adiponectin, and that they mediate increased AMP kinase and PPAR-alpha ligand activities, as well as fatty-acid oxidation and glucose uptake by adiponectin.

OBJECTIVES: Neoendothelialization by circulating endothelial progenitor cells has been a topic of recent research. The extent and scale of this process in humans is not well understood. We examined the extent of neoendothelialization of the aorta and peripheral arteries in the case of a patient who underwent peripheral blood stem cell transplantation for acute radiation syndrome. METHODS: Human tissue samples from the aorta and peripheral arteries were obtained at autopsy. Endothelial cells were isolated, confirmed by von Willebrand factor immunostaining, and then subjected to fluorescent in situ hybridization analysis using X- and Y-chromosome specific probes to examine neoendothelialization by donor cells as possible in this case in which the donor and recipient were of different genders. RESULTS: The aorta showed almost 25% of all endothelial cells to be replaced by donor-origin endothelial cells. The peripheral arteries were also replaced but to a lesser extent. DISCUSSION: The present study provides evidence that peripheral blood is a source of endothelial progenitor cells in humans. Neoendothelialization of the aorta occurs to a significant extent under certain conditions suggesting the potential for exploitation of therapeutic neovascularization by transplantation of circulating endothelial progenitor cells.

Although we and others have generated IRS-2 knock-out (IRS-2(-/-)) mice, significant differences were seen between the two lines of IRS-2(-/-) mice in the severity of diabetes and alterations of beta-cell mass. It has been reported that although IRS-1 and IRS-3 knock-out mice showed normal blood glucose levels, IRS-1/IRS-3 double knock-out mice exhibited marked hyperglycemia. Thus, IRS-1 and IRS-3 compensate each other's functions in maintaining glucose homeostasis. To assess the effect of genetic background and also ablation of IRS-3 on IRS-2(-/-), we generated IRS-2/IRS-3 double knock-out (IRS-2(-/-)IRS-3(-/-)) mice by crossing IRS-3(-/-) mice (129/Sv and C57Bl/6 background) with our IRS-2(-/-) mice (CBA and C57Bl/6 background). Intercrosses of IRS-2(+/-)IRS-3(+/-) mice yielded nine genotypes, and all of them including IRS-2(-/-)IRS-3(-/-) mice were apparently healthy and showed normal growth. However, at 10-20 weeks of age, 20-30% mice carrying a null mutation for the IRS-2 gene, irrespective of the IRS-3 genotype, developed diabetes. When mice with diabetes were excluded from the analysis of glucose and insulin tolerance test, IRS-2(-/-)IRS-3(-/-) showed a degree of glucose intolerance and insulin resistance similar to those of IRS-2(-/-) mice. Both IRS-2(-/-) and IRS-2(-/-)IRS-3(-/-) mice had moderately reduced beta-cell mass despite having insulin resistance. Insulin-positive beta-cells were decreased to nearly zero in IRS-2(-/-) mice with diabetes. Although Pdx1 and glucose transporter 2 expressions were essentially unaltered in islets from IRS-2(-/-) mice without diabetes, they were dramatically decreased in IRS-2(-/-) mice with diabetes. Taken together, these observations indicate that IRS-3 does not play a role compensating for the loss of IRS-2 in maintaining glucose homeostasis and that the severity of diabetes in IRS-2(-/-) mice depends upon genetic background, suggesting the existence of modifier gene(s) for diabetes in mice of the 129/Sv genetic strain.

The efficacy of electrical defibrillation is considered to be related to the autonomic status. In search of a possible adjunct to enhance the therapeutic performance of an implantable cardioverter-defibrillator, we investigated whether parasympathetic manipulation by cervical vagal nerve stimulation (VNS) increases defibrillation efficacy. The effects of VNS on transcardiac defibrillation threshold (DFT) were assessed in 55 anesthetized dogs. In neurally intact dogs, right and left unilateral VNS at 10 mA for 7 seconds significantly decreased the DFT after 10 seconds of ventricular fibrillation (control: 3.1±0.9 J, right: 2.1±0.9 J [Δ-35±12%, P&lt 0.0001], left: 2.2±0.8 J [Δ-31±11%, P&lt 0.0005]), while bilateral VNS did not (2.8±1.0 J). In dogs with decentralized vagus nerves, both unilateral and bilateral VNS decreased the DFT. The extent of the VNS-induced decrease in DFT was dependent on the current and the duration of stimulation. We conclude that unilateral VNS decreases the DFT, while bilateral VNS paradoxically has no effect on the DFT unless the vagi are decentralized. Copyright © 2003 by the Japanese Heart Journal.

"Standards on the Implementation of Clinical Trials on Drugs (New GCP)" is a Japanese government policy established in April 1998 with the aim of satisfying scientific and ethical requirements for industry-sponsored research, i.e., registration-directed clinical trials and clinical trials intended to support reexamination or reevaluation applications. Since then, efforts for more effective implementation of clinical trials have been promoted, including establishment of a system to invite more active participation of subjects in clinical trials and improvement of a network of medical institutions conducting clinical trials. These efforts should help to reactivate clinical trials in Japan, which reportedly have become stagnant. Although the New GCP addresses the quality of industry-sponsored clinical trials, investigators also construct study protocols without industry involvement. We reviewed clinical trials submitted by investigators at Gunma University Hospital to institutional review boards (IRBs) from June 1999 to February 2002. Ten clinical research coordinators contributed to the present survey. A total of 151 investigator-initiated clinical trials reviewed included a wide variety of content; and investigators from many institutions and organizations conducted trials. Most of the ethical guidelines for approving proposed trials represented the provisions of the Declaration of Helsinki. However, additional guidelines prepared by the Japanese Ministry of Health, Labour and Welfare were also helpful. Development of a support system for clinical trails requires the contribution of clinical research coordinators. Flexible management and careful attention to both the protocol and its execution by the investigators were also important for promoting clinical trials on the basis of meticulous patient care. (Jpn Heart J 2003; 44: 235-242).

Heme oxygenase-1 (HO-1) is an inducible form of heme oxygenase that catabolizes heme to carbon monoxide, biliverdin, and ferrous iron. We have investigated whether HO-1 can induce angiogenic effects in vivo. Rats were subjected to a bolus injection of either wild type adenovirus (ad-wt) or adenovirus encoding HO-1 (ad-HO-1) through the right femoral artery, which was then removed immediately. HO-1 gene transfer resulted in about a sixfold increase in HO-1 protein levels as compared to the non-treated animals. The increase in both blood flow and capillary density was significantly greater in the ischemic hindlimbs that had been injected with ad-HO-1 than in those injected with ad-wt. These angiogenic effects of ad-HO-1 infection could be completely abolished by treating the animals with the HO inhibitor, zinc protoporphyrin, indicating that they were specifically due to the expression of HO-1. Thus, HO-1 gene transfer improves the blood flow in ischemic hindlimb, at least in part, via angiogenesis facilitated by the induction of this molecule. (C) 2003 Elsevier Science (USA). All rights reserved.

三尖弁狭窄症(TS)を合併し,焼灼に難渋した房室結節回帰性頻拍の1例を経験した.解剖学的アプローチでコッホ三角部と考えられる部位の電位はすべていわゆるon the valve型であり,small A largeV型の電位はヒス東電位記録部位(HBE)から2mm以内でしか記録されず,スローポテンシャルは記録されなかった.3次元エレクトロアナトミカルマッピングシステム(CARTOTM)を用いて,HBEをマッピングし,解剖学的アプローチで冠静脈洞側から焼灼を開始したが,成功通電部位はHBEから3mmの点であり,この局所電位もon the valve型であった.右房右室間に拡張期に10mmHgの圧格差を認め,右房造影と経食道心エコーでTSを認めた.形態的に三尖弁輪の異常を伴い,ヒス束近傍での通電を要する症例ではCARTOTMは有用と考えられ報告した.

Expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1alpha (HIF-1alpha), a transcription factor involved in the VEGF induction, was examined in the myocardium. In the 10-day-old chick embryonic hearts and ventricular myocytes, the mRNA species encoding VEGF and HIF-1alpha were abundantly expressed even at the basal conditions. The steady-state levels of the VEGF mRNA were regulated by various protein kinases. In the cultured neonatal rat ventricular myocytes,VEGF expression was upregulated by lipopolysaccharide. These data suggest that VEGF and HIF-1alpha expressed in cardiac myocytes may play significant roles in cardiovascular development. Furthermore, the cardiac myocyte-derived VEGF may also contribute to the pathogenesis of systemic inflammatory response syndrome, including myocardial interstitial edema.

The background cationic current and the effects of lysophosphatidylcholine (LPC) were investigated in cultured rabbit coi-onary arterial smooth muscle cells (CASMCs) by using patch clamp techniques and [Ca2+](i) measurements. Here, we provided evidence that background nonselective cation current (I-NSC) contributed to form membrane potential, and LPC further induced I NSC' followed by depolarizing the membrane. The background and LPC-activated I-NSC were blocked by La3+ and Gd3+ but not by nicardipine and verapamil. LPC increased [Ca2+](i) due to Ca2+ influx. I-NSC plays important roles in forming membrane potentials and regulating [Ca2+](i) of CASMCs under various pathophysiological conditions such as ischemia.

KLF5/BTEB2 is a Kruppel-like zinc-finger type transcription factor of a nonmuscle type myosin heavy chain gene SMemb, which is markedly induced in phenotypically modulated smooth muscle (SMC). KLF5/BTEB2 expression in SMC is downregulated with vascular development in vivo but upregulated in neointima that is produced in response to vascular injury. KLF5/BTEB2 activates the promoter of not only SMemb gene, but also of other genes which are actvated in synthetic SMC, including plasminogen activator inhibitor-1 (PAI-1), iNOS, PDGF-A, Egr-1 and VEGF receptors. Mitogenic stimulation activates KLF5/BTEB2 gene expression through MEK1 and Egr-1. KLF5/BTEB2 +/- mice showed a marked reduction in neointimal formation, angiogenesis and cardiac fibrosis induced by various kinds of stress. We suggest that KLF5/BTEB2 is a crucial transcription factor involved in smooth muscle phenotypic modulation as well as mesenchymal cell activation in cardiovascular disease.

As the number of the genetic studies has rapidly increased in recent years, there has been growing concern that the privacy of the participants in such studies can be invaded unless effective measures are adopted to protect confidentiality. It is crucial for the scientific community to establish a method to anonymize DNA samples so that the public will trust genetic researchers. Here, we present a reliable and practical method of making DNA samples used in the genetic research anonymous. It assures complete anonymity by coding samples and personal information twice. Since it does not require equipment, such as bar-code readers or a software package, its cost is nominal compared with the laboratory costs. All institutions engaged in genetic research may wish to take measures such as the one described here to ensure the privacy and confidentiality of the participants in their genetic studies.

Background/Aims: Histamine H2 receptor antagonists are considered to exert their effects on gastric acid secretion more rapidly than proton pump antagonists. However, there are no reports concerning the direct interaction of a histamine H2 receptor antagonist with the human H2 receptor in terms of onset of action. This study aims to characterize how rapidly famotidine and ranitidine, the most widely used histamine H2 receptor antagonists, interact with the human histamine H2 receptor. Methods: HEK293 cell lines, stably expressing human histamine H2 receptors, were obtained. The dose- and time-dependent effects of famotidine and ranitidine on [3H]-tiotidine binding and histamine-stimulated cAMP production were analyzed. Results: Ranitidine inhibited both [3H]-tiotidine binding and histamine-stimulated cAMP production more promptly than did famotidine. Inhibition of histamine- stimulated cAMP production by Cmax doses of famotidine (20 mg p.o.) and ranitidine (150 mg p.o.) peaked by 15 and 2 min, respectively. [ 3H]-Tiotidine binding was not saturated by 60 min at the famotidine Cmax, while the ranitidine Cmax had produced saturation by 15 min. Conclusion: Ranitidine inhibits the human histamine H2 receptor very rapidly. Copyright © 2003 S. Karger AG, Basel.

Leptin-deficient ob/ob mice show many characteristics of obesity, including excess peripheral adiposity as well as severe hepatic steatosis, at least in part, due to increased hepatic lipogenesis. Polyunsaturated fatty acids (PUFAs) are not only ligands for peroxisome proliferator-activated receptor (PPAR) α but are also negative regulators of hepatic lipogenesis, which is thought to be mediated by the repression of sterol regulatory element-binding protein (SREBP)-1. We have previously shown that the disruption of SREBP-1 in ob/ob mice decreased their liver triglyceride storage. To examine whether PUFAs could reduce hepatic triglyceride deposition, we challenged ob/ob mice with dietary PUFA. It is demonstrated that PUFA markedly decreased the mature form of SREBP-1 protein and thereby reduced the expression of lipogenic genes such as fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD1) in the livers of ob/ob mice. Consequently, the liver triglyceride content and plasma alanine aminotransferase (ALT) levels were decreased. Furthermore, both hyperglycemia and hyperinsulinemia in ob/ob mice were improved by PUFA administration, similar to the effect of PPARα activators. In conclusion, PUFAs ameliorate obesity-associated symptoms, such as hepatic steatosis and insulin resistance, presumably through both down-regulation of SREBP-1 and activation of PPARα.

We recently isolated a Krüppel-like zinc-finger transcription factor 5 (KLF5; also known as BTEB2 and IKLF), which is markedly induced in activated vascular smooth-muscle cells and fibroblasts. Here we describe our analysis of the in vivo function of KLF5 using heterozygous KLF5-knockout mice (Klf5(+/-)). In response to external stress, Klf5(+/-) mice showed diminished levels of arterial-wall thickening, angiogenesis, cardiac hypertrophy and interstitial fibrosis. Also, angiotensin II induced expression of KLF5, which in turn activated platelet-derived growth factor-A (PDGF-A) and transforming growth factor-beta (TGF-beta) expression. In addition, we determined that KLF5 interacted with the retinoic-acid receptor (RAR), that synthetic RAR ligands modulated KLF5 transcriptional activity, and that in vivo administration of RAR ligands affected stress responses in the cardiovascular system in a KLF5-dependent manner. KLF5 thus seems to be a key element linking external stress and cardiovascular remodeling.