Search

Background To secure human resources for occupational medicine, it is important to analyse occupational physician retention trends and the factors associated with retention. However, little is currently known about this topic. Aims To identify occupational physician retention trends, to identify factors associated with this retention and to discuss the policy implications of the findings. Methods We analysed data from the biannual national physician census surveys conducted by the government of Japan from 2002 to 2014. In this study, those who chose 'working as an occupational physician' as their workplace/type of work from a pre-determined list in the survey questionnaire were considered full-time occupational physicians. We presented retention trends by calculating the annual retention rate for each set of two consecutive surveys. We then used logistic regression to identify factors associated with retention among occupational physicians. Results The annual retention rate of full-time occupational physicians from 2012 to 2014 was estimated as 76%, which represents a 6% improvement in retention over the study period. The odds of continuing to practise as an occupational physician were higher for occupational physicians working in cities compared with those working in towns or villages. Conclusions Improving and facilitating smooth transitions between clinical practice and occupational medicine would help to secure human resources in occupational medicine, even if the current trend of low retention continues.

Background Coronary computed tomography angiography (CTA) has demonstrated high diagnostic accuracy for detection of coronary artery stenosis, and healthcare providers can detect coronary artery disease in earlier stages before it develops into more serious clinical conditions such as acute myocardial infarction (AMI). We hypothesized that the mortality ratio of AMI in regions with a higher density of coronary CTA is lower than that in regions with a lower density of coronary CTA. Methods This ecological and cross-sectional study using secondary data targeted all secondary medical service areas (SMSAs) in Japan (n = 349). We obtained the numbers of cardiologists, institutions with coronary CTA, and institutions with a cardiac catheterization laboratory (CCL) as medical resources, socioeconomic factors, lifestyle factors, exercise habit factors, and AMI mortality data from a Japanese national database. We evaluated the association between the number of these medical resources and the standardized mortality ratio (SMR) of AMI in each SMSA using a hierarchical Bayesian model accounting for spatial autocorrelation (i.e., a conditional autoregressive model). We assumed a Poisson distribution for the observed number of AMI-related deaths and set the expected number of AMI-related deaths as the offset variable. Results The number of institutions with coronary CTA was negatively and significantly associated with the SMR of AMI (relative risk [RR] 0.900; 95% credible interval [CI] 0.848–0.953), while the SMR in each SMSA was not significantly associated with the number of either cardiologists (RR 0.997; 95% CI 0.988–1.004) or institutions with a CCL (RR 1.026; 95% CI 0.963–1.096). Conclusions We observed a significant association between the number of institutions with coronary CTA and the SMR of AMI. Effective allocation of coronary CTA in each region is recommended, and it would be important to clarify the standing position of coronary CTA in regional networking for AMI treatment in the future. Electronic supplementary material The online version of this article (10.1186/s12942-018-0133-0) contains supplementary material, which is available to authorized users.

Background The board certification system serves as a quality assurance system for physicians, and its design and operation are important health policy issues. In Japan, board certification was established and operated independently by academic societies and has not been directly linked to reimbursement systems. The phenomenon of younger physicians seeking specialist careers has raised concerns about acceleration of the tendency of fewer physicians working in rural areas and the maldistribution of physicians. Little is known about the associations between physicians’ geographical migration patterns and board certification status changes or between the continuation of urban/rural practice and the maintenance of board certification. This study aimed to identify these associations and to discuss their policy implications. Methods We analyzed 2012 and 2014 data from the Survey of Physicians, Dentists, and Pharmacists, a national census survey. To analyze geographical migration patterns, transitions in practice location (rural, intermediate, and urban) were analyzed by board certification status change (new, lost, consistently certified, and consistently uncertified). Logistic regression analysis was conducted to assess whether the odds of migrating to more urban/rural municipalities were associated with board certification status changes, adjusting for covariates, and whether practicing in a rural area was associated with maintaining board certification. Results Among 18,726 newly board-certified physicians, 94.9% (13,435/14,150) of those working in urban areas before certification remained in urban areas, whereas 64.6% (393/608) of those working in rural areas stayed in rural areas. Those who were newly certified had higher odds of moving to more urban areas, adjusting for covariates. Those who stayed in rural areas showed lower odds of maintaining board certification, adjusting for covariates. Conclusions Newly board-certified physicians are more likely to migrate to other types of areas, particularly more urban areas, than other physicians. Allocating more training quotas to rural areas could be one option for leveling the distribution of specialists. It also appeared that those practicing in rural areas have difficulty maintaining their certification, so the need to establish a support system for already-certified physicians in rural areas should be emphasized. Electronic supplementary material The online version of this article (10.1186/s12913-018-3441-y) contains supplementary material, which is available to authorized users.

We comprehensively evaluated cognitive and social functioning in patients requiring long-term inpatient psychiatric care using the International Classification of Functioning, Disability, and Health.We surveyed 1967 patients receiving long-term inpatient psychiatric care. Patients were further categorized into an old long-stay group (n = 892,5 years in hospitals) and a new long-stay group (n = 1075, 1-5 years in hospitals). We obtained responses for all the International Classification of Functioning, Disability, and Health items in domain b (Body Functions) and domain d (Activities and Participation). We estimated weighted means for each item using the propensity score to adjust for confounding factors.Responses were received from 307 hospitals (response rate of hospitals: 25.5%). Cognitive and social functioning in the old long-stay group was more severely impaired than in the new long-stay group. No statistically significant differences were observed regarding the International Classification of Functioning, Disability, and Health items associated with basic activities of daily living between the two groups.Combined therapy consisting of cognitive remediation and rehabilitation on social functioning for this patient population should be started from the early stage of hospitalization. Non-restrictive, independent environments may also be optimal for this patient population. Implications for rehabilitation Rehabilitation of cognitive and social functioning for patients requiring long-term inpatient psychiatric care should be started in the early stages of hospitalization. In psychiatric fields, the International Classification of Functioning, Disability, and Health checklist could facilitate individualized rehabilitation planning by allowing healthcare professionals to visually assess the comprehensive functioning of each patient using graphics such as radar charts.

Parathyroid hormone-related protein (PTHrP) is detected in many aggressive tumors and involved in malignant conversion; however, the underlying mechanism remains obscure. Here, we identified PTHrP as a mediator of epidermal growth factor receptor (EGFR) signaling to promote the malignancies of oral cancers. PTHrP mRNA was abundantly expressed in most of the quiescent oral cancer cells, and was significantly upregulated by EGF stimulation via ERK and p38 MAPK. PTHrP silencing by RNA interference, as well as EGFR inhibitor AG1478 treatment, significantly suppressed cell proliferation, migration, and invasiveness. Furthermore, combined treatment of AG1478 and PTHrP knockdown achieved synergistic inhibition of malignant phenotypes. Recombinant PTHrP substantially promoted cell motility, and rescued the inhibition by PTHrP knockdown, suggesting the paracrine/autocrine function of PTHrP. These data indicate that PTHrP contributes to the malignancy of oral cancers downstream of EGFR signaling, and may thus provide a therapeutic target for oral cancer.

Objective— C-reactive protein (CRP), an obesity-related inflammatory marker, is a promising predictor for cardiovascular disease and may be a mediator for atherogenesis. It has been reported that diet-induced weight loss lowered CRP levels. However, the effect of exercise training, another therapy that can reduce weight, on CRP is still unclear. We examined effects of exercise training with weight loss on CRP levels and conventional cardiovascular risks. Methods and Results— A total of 227 apparently healthy women were recruited, and 199 subjects (average age 52 years) completed a 2-month weight reduction program consisting of supervised aerobic exercises. After the program, weight was reduced from 65.8 to 62.8 kg ( P P Conclusions— Exercise training with weight reduction disproportionately lowered CRP levels. Considering inflammatory status, there might be an optimal pace of exercise with weight loss.

✓ Letter-perception centers are not held in as high regard as motor- and language-related cortices during planning of neurosurgical procedures, and there have been no reports suggesting cortical reorganization of reading ability. The authors describe a patient with a left mesial temporal glioma in whom two letter-perception centers (the anterior portion of the left superior temporal gyrus and the left fusiform gyrus) were successfully localized before surgery by performing magnetoencephalography (MEG) during reading tasks. Control MEG examinations of 15 healthy volunteers were also performed to assist in a careful interpretation of patient results. Although a radical resection of the mesial temporal glioma, which involved the left fusiform gyrus, caused severe dyslexia, the patient's impaired reading skills improved gradually during a 1-year postoperative period. In the meantime, the spared left superior temporal gyrus displayed an overshot recovery of MEG responses. During the postoperative period there was no obvious recovery in MEG signals and no compensatory activity in the contralateral fusiform gyrus. This case demonstrates that lexicosemantic centers involved in the reading process can be noninvasively localized using MEG and that the results obtained are highly reliable for surgical planning. The results of the repeated MEG reflected sequentially the patient's recovery from dyslexia. This is the first report in which MEG studies have been shown to predict preoperatively the risk of dyslexia and demonstrate its serial physiological recovery.

In the hearts of spontaneously hypertensive rats, mRNA of the renin-angiotensin system (renin, angiotensinogen, and angiotensin converting enzyme) was expressed. Level of angiotensinogen and renin mRNA expressed in ventricles, and angiotensinogen mRNA expressed in fibroblasts from SHR were higher than those from WKY. ACE mRNA was also more strongly expressed in the ventricles and fibroblasts from SHR compared with those of WKY. We investigated the effects of angiotensin II on cardiac collagen synthesis in cardiac fibroblasts of 10-week-old spontaneously hypertensive rats and age-matched Wistar-Kyoto rats. Basal collagen synthesis in cardiac fibroblasts from spontaneously hypertensive rats was 1.6-fold greater than that in the cell of Wistar-Kyoto rats. Angiotensin II stimulated collagen synthesis in cardiac fibroblasts in a dose-dependent manner. The responsiveness of collagen production to angiotensin II was significantly enhanced in cardiac fibroblasts from spontaneously hypertensive rats (100 nM angiotensin II resulted in 185 ± 18% increase above basal levels, 185 ± 18 versus 128 ± 19% in Wistar-Kyoto rats, p < 0.01). This effect was receptor-specific, because the competitive inhibitor saralasin and MK 954 blocked it. These results indicate that collagen production was enhanced in cardiac fibroblasts from spontaneously hypertensive rats, that angiotensin II had a stimulatory effect on collagen synthesis in cardiac fibroblasts, and that cardiac fibroblasts from spontaneously hypertensive rats were hyperresponsive to stimulation by angiotensin II. These findings suggest that the cardiac renin-angiotensin system may play an important role in collagen accumulation in hypertensive cardiac hypertrophy.

The effects of L-arginine on spontaneous contraction of endothelium-denuded longitudinal preparations of the rat portal vein were studied. L-arginine increased the frequency of spontaneous contraction concentration-dependently between 10 microM and 1 mM. Changes in contraction amplitude and duration were not remarkable. D-arginine had a negligible effect on spontaneous contraction. N(omega)-nitro-L-arginine (1 mM) did not affect spontaneous contraction or the response to L-arginine. Addition of N(G)-monomethyl-L-arginine (1 mM), l-lysine (1 mM) or N-ethymaleimide (0.1 mM) increased the frequency of spontaneous contractions and inhibited the effect of L-arginine. Glibenclamide (10 microM) did not affect spontaneous contraction or the response to L-arginine. Spontaneous increase in concentration of intracellular Ca2+, estimated as the ratio of Fura-PE3 fluorescence occurred synchronously with spontaneous contraction. Spontaneous increase in concentration of intracellular Ca2+ occurred more frequently in the presence of L-arginine (1 mM). L-arginine (1 mM) also increased the number of action potential bursts/min in the longitudinal smooth muscle layer. L-arginine (1 mM) also depolarized cell membranes. This study indicates that L-arginine increases the frequency of spontaneous contraction of longitudinal muscle in the rat portal vein by membrane depolarization through mechanisms that do not involve nitric oxide or the inhibition of ATP-sensitive K+ channels.

Although the types of pathophysiological stimulation that initiate an overexpression of OPN have yet to be determined, we hypothesized that mechanical stress is one of the candidates which initiates OPN expression in vascular smooth muscle cells. Cell proliferation assay indicated that a pure atmospheric pressure of 160 mmHg activated cell proliferation by 11% in human aortic smooth muscle cells (HASMC) compared to nonpressurized controls. Immunoblot analysis probed with an anti-OPN antibody demonstrated a 50% increase in OPN. Dual-luciferase reporter assay demonstrated that OPN promoter, corresponding to the −771 through −1 region of OPN gene, was highly responsive to pure atmospheric pressure by ten times that of the control. From these observations, we concluded that pure atmospheric pressure directly promotes an expression of OPN in HASMC, with these results also suggesting that high blood pressure-mediated mechanical compression is involved in the process of atherosclerosis and remodeling via OPN expression in HASMC.

This study examined the effects of long-term treatments with the angiotensin-converting enzyme inhibitor, enalapril, and the calcium antagonist, amlodipine, on the morphologic changes, progressive left ventricular dysfunction, and gene expression of the ryanodine receptor (RyR) and phospholamban (PLN) in dilated cardiomyopathy. From the ages of 5 through 20 weeks, dilated cardiomyopathic hamsters, BIO53.58 (BIO), and control hamsters, F1b, orally received either enalapril or amlodipine. Cardiac function was assessed by echocardiography. At the age of 20 weeks, the collagen volume fractions were analyzed by the stereologic method. RyR and PLN messenger RNAs (mRNAs) were examined by Northern blot in the amlodipine group. In BIO, the reduction of left ventricular percentage of fractional shortening was attenuated in the enalapril group (p < 0.05) and amlodipine group (p < 0.001), and the increase in the collagen volume fraction and the loss of myocytes were suppressed in the amlodipine group compared with the untreated group. RyR mRNA level decreased in BIO (p < 0.01) compared with F1b, but PLN mRNA level was unchanged. RyR and PLN mRNA levels were unaffected by the treatment with amlodipine. Enalapril and amlodipine prevent progressive remodeling and reduce cardiac dysfunction in BIO. Amlodipine prevents fibrosis and cell death without modifying RyR and PLN mRNA levels in BIO.

Hypertensive cardiac hypertrophy is associated with the accumulation of collagen in the myocardial interstitium. Previous studies have demonstrated that this myocardial fibrosis accounts for impaired myocardial stiffness and ventricular dysfunction. Although cardiac fibroblasts are responsible for the synthesis of fibrillar collagen, the factors that regulate collagen synthesis in cardiac fibroblasts are not fully understood. We investigated the effects of angiotensin II on cardiac collagen synthesis in cardiac fibroblasts. Cardiac fibroblasts of 10 week old spontaneously hypertensive rats and age-matched Wistar-Kyoto rats were prepared and maintained in culture medium supplemented with 10% fetal calf serum. The expression of mRNA of the renin-angiotensin system (renin, angiotensinogen, angiotensin converting enzyme) was determined by using a ribonuclease protection assay. Basal collagen synthesis in cardiac fibroblasts from spontaneously hypertensive rats was 1.6 fold greater than that in the cell of Wistar-Kyoto rats. Angiotensin II stimulated collagen synthesis in cardiac fibroblasts in a dose-dependent manner. The responsiveness of collagen production to angiotensin II was significantly enhanced in cardiac fibroblasts from spontaneously hypertensive rats (100 nM angiotensin II resulted in 185 ± 18% increase above basal levels, 185 ± 18 versus 128 ± 19% in Wistar-Kyoto rats p < 0.01). This effect was receptor-specific, because it was blocked by the competitive inhibitor saralasin and MK 954. These results indicate that collagen production was enhanced in cardiac fibroblasts from spontaneously hypertensive rats, that angiotensin II had a stimulatory effect on collagen synthesis in cardiac fibroblasts, and that cardiac fibroblasts from spontaneously hypertensive rats were hyper-responsive to stimulation by angiotensin II. Level of angiotensin and renin mRNA expressed in ventricles, and angiotensinogen mRNA expressed in fibroblasts from SHR were higher than those from WKY. These findings suggest that the cardiac renin-angiotensin system may play an important role in collagen accumulation in hypertensive cardiac hypertrophy.

近年の生化学,遺伝子工学の研究の発展によって循環器領域でも,日常外来検査で簡単に行う事が出来,しかも正確な診断が出来る検査が幾つか出現してきた.たとえば心房性ナトリウム利尿ペプチド(ANP, BNP),は心不全時に増加し,その予後との関連が検討されている.また心筋梗塞時にも増加し,心筋梗塞巣の大きさや心室リモデリングとの関連も検討されてきた.トロポニンT,ミオシン軽鎖,ミオグロビンなどは心筋梗塞時にそれぞれ特異な遊出パターンを示すので,これらを組み合わせて測定することによって,より正確な病態把握が可能になる.

To examine the contribution of the renin-angiotensin system to hypertrophic cardiomyopathy (HCM), we studied 96 patients with HCM (mean age 50 years, 55% male), 105 of their unaffected siblings and offspring, and 160 healthy subjects without known hypertension and left ventricular hypertrophy (LVH) who were frequency matched to cases by age and sex. Patients were divided into familial or sporadic HCM (FHCM or SHCM) groups with or without affected members of their family. The region of interest in the angiotensinogen (AGT) gene, the missense mutation with methione-to-threonine amino acid substitution at codon 235 in angiotensinogen (M235T), was amplified by polymerase chain reaction with the use of allele-specific oligonucleotide primers flanking the polymorphic region of the AGT gene to amplify template deoxyribonucleic acid prepared from peripheral leukocytes. The T allele frequency was higher in the SHCM group than in unaffected siblings and offspring (88% vs 78%, X2 = 4.6, p < 0.05). The M allele frequency was higher in unaffected siblings and offspring than in patients with SHCM (23% vs 12%, X2 = 4.6, p < 0.05). The T allele frequency among unaffected siblings and offspring was similar to that observed in healthy subjects (78% vs 78%). We conclude that HCM, especially in sporadic cases, is partially determined by genetic disposition. The molecular variant of angiotensinogen T235 seems to be a predisposing factor for cardiac hypertrophy in HCM and carries an approximately twofold increased risk.

Congestive heart failure (CHF) patients share several similar features, such as reduced cardiac contractility and neurohumoral activation to compensate the impaired cardiac function. In CHF patients, the cardiac renin-angitensin (RA) system, receptors, GTP-binding proteins, and their effector molecules are inevitably exposed to chronically elevated neurohumoral stimulation. A widely recognized concept is that a chronic increase in such stimulation can desensitize target cell receptors and the post-receptor signal transducing pathway. Recently, reports of several studies have indicated that the inhibitory GTP-binding protein (Gi) can be increased in CHF patients and animal models. Although direct evidence for a change in catalytic protein of adenylyl cyclase has not been found, limited information has suggested a reduced catalytic activity in terminally failing hearts. In this paper, we have assessed the changes in beta AR, GTP-binding protein, catalytic protein and beta ARK. We also examined angiotensinogen mRNA expression in failing heart. It was detected not only in the liver, but also in both the atrial and ventricular heart tissues, suggesting that angiotensinogen is synthesized in the human heart. Immunohistochemical studies revealed a stronger reaction in the endocardial layer of the human left ventricle than in the epicardial layer, and intense immunoreactivity in the conduction system and right atrium. Our experiments revealed a widespread immunopositive reaction for angiotensinogen in the left ventricle of diseased hearts. In the non-diseased heart, ACE and AT1 receptor RNA are present in ventricular muscles. Renin and Ao mRNA could not be detected in the subendocardium of non-diseased left ventricle, but both were present in the left ventricle of diseased hearts. These data indicate that the cardiac RA system plays an important role in the deterioration of cardiac function.

Background Regional disparity in suicide rates is a serious problem worldwide. One possible cause is unequal distribution of the health workforce, especially psychiatrists. Research about the association between regional physician numbers and suicide rates is therefore important but studies are rare. The objective of this study was to evaluate the association between physician numbers and suicide rates in Japan, by municipality. Methods The study included all the municipalities in Japan (n = 1,896). We estimated smoothed standardized mortality ratios of suicide rates for each municipality and evaluated the association between health workforce and suicide rates using a hierarchical Bayesian model accounting for spatially correlated random effects, a conditional autoregressive model. We assumed a Poisson distribution for the observed number of suicides and set the expected number of suicides as the offset variable. The explanatory variables were numbers of physicians, a binary variable for the presence of psychiatrists, and social covariates. Results After adjustment for socioeconomic factors, suicide rates in municipalities that had at least one psychiatrist were lower than those in the other municipalities. There was, however, a positive and statistically significant association between the number of physicians and suicide rates. Conclusions Suicide rates in municipalities that had at least one psychiatrist were lower than those in other municipalities, but the number of physicians was positively and significantly related with suicide rates. To improve the regional disparity in suicide rates, the government should encourage psychiatrists to participate in community-based suicide prevention programs and to settle in municipalities that currently have no psychiatrists. The government and other stakeholders should also construct better networks between psychiatrists and non-psychiatrists to support sharing of information for suicide prevention.

The effects of transforming growth factor beta-1 on concentration of intracellular Ca2+ changes in the presence of isoproterenol were studied in cardiac fibroblasts. Transforming growth factor beta-1 effect on cyclic-AMP production and ligand assay of beta-adrenergic receptors were also examined. Production of cyclic-AMP in fibroblasts preincubated with transforming growth factor beta-1 decreased compared with non-transforming growth factor beta-1-treated fibroblasts in the presence of isoproterenol. An increase of intracellular Ca2+ concentration in the presence of isoproterenol was also inhibited in transforming growth factor beta-1-treated fibroblasts. Islet-activating protein did not restore these reactions of transforming growth factor beta-1. Concentration change of intracellular calcium under the treatment of transforming growth factor beta-1 was unaffected by forskolin addition. Binding of [3H]CGP-12177 was decreased to 47% of control preincubated for 24 h with transforming growth factor beta-1 in fibroblasts. Scatchard plots suggested a decrease in beta-adrenergic receptor number without specific change in receptor affinity. These results suggested that transforming growth factor beta-1 modulates the signal transduction through beta-adrenergic receptor and intracellular Ca2+ concentration by regulating the number of receptor in fibroblasts.

Extrahepatic synthesis and localization of angiotensinogen (ATN) have been described in animals, thus establishing the tissue renin-angiotensin (RA) system. However, there had been no reports of tissue RA systems in human organs, including the heart. In earlier, we have reported the possibility of ATN synthesis in the human heart using ribonuclease protection assay system. ATN mRNA was detected not only in the liver, but also in both the atrial and ventricular heart tissues, suggesting that ATN is synthesized in the human heart. In this report, we looked for the distribution of ATN in diseased human heart. Northern blot hybridization of cDNA with total RNA extracted from human liver, brain, kidney, atrial and ventricular tissues revealed that ATN mRNA exists in cardiac ventricule. Immunohistochemical studies using a specific antibody to ATN revealed a stronger reaction in the endocardial layer of the human left ventricle, than in the epicardial layer, and intense immunoreactivity in the conduction system and right atrium. This distribution pattern was similar to that of human atrial natriuretic peptide (hANP), which functions a smooth muscle relaxant. Double immunostaining of ATN and hANP demonstrated that all myocytes in the right atrium had immunopositive reactions to ATN, hANP or both of ATN and hANP. Double immunoelectron staining enabled us to show more detailed localization of ATN and hANP; hANP only existed in the specific granules and ATN existed in the myofibril, but not in the granule. Furthermore, our experiments provide evidence of ATN in healthy human hearts and also reveal a widespread immunopositive reaction for ATN in the left ventricle of diseased hearts.

The accumulation of inositol 1,4,5-trisphosphate (IP3) after hormonal stimulation has a physiological role, possibly by alteration of Ca2+ levels in cardiac myocyte. However, this accumulation has not been studied under pathophysiological conditions. In this report, we examine phosphatidylinositol metabolism during cellular response to norepinephrine in pressure-overloaded hypertrophic rat heart. After stimulation with norepinephrine, the accumulations of IP3 and diacylglyceride significantly increased in isolated myocytes from stroke-prone spontaneously hypertensive rat (SHRSP) heart, indicating phosphatidylinositol-specific phospholipase C activity increased in SHRSP heart cells. Protein kinase C activity was also enhanced in SHRSP, with a marked increase in particulate activity. We determined the intracellular calcium concentration and found it to be higher in SHRSP than in Wistar-Kyoto (WKY) rats at 30-40 weeks of age. Ca2+ influx was also elevated in SHRSP stimulated by norepinephrine. In SHRSP heart, cytosolic Ca2+ concentration may rise quickly in response to some stimuli, such as alpha 1-adrenergic stimulation, which is shown to be one of the pathways that increases cytosolic Ca2+ levels in hypertrophied rat heart. These data suggest that a part of the phosphatidylinositol-turnover pathway, such as the phosphatidylinositol 4,5-bisphosphate-IP3-Ca2+ pathway or the diacylglyceride-protein kinase C pathway, may play an important role in the development of hypertrophy in SHRSP heart.

It is known that inositol (1, 4, 5)-trisphosphate (IP3) stimulates Ca2+ release from sarcoplasmic reticulum (SR) in several tissues, but in cardiac myocytes this phenomenon has not been confirmed. The purpose of the present study was to confirm the effect of (1, 4, 5)-IP3 on Ca2+ release from SR in cardiac myocytes. The effect of IP3 on Ca2+ release from SR in hypertrophic cardiac cells was also determined. We examined the effects of IP3 on Ca2+ release from cardiac myocyte SR by the digital-image method in a single cell. We also determined the effect of IP3 on calcium release from isolated SR. SR was prepared from spontaneous hypertensive rat hearts and Wistar kyoto rat hearts. The SR was prelabeled with 45Ca2+, and then incubated with the indicated concentrations of IP3 for 1 min at 37 degrees C. In cardiac myocytes treated with saponin, Ca2+ release stimulated by 10 microM (1, 4, 5)-IP3 was detected by fura-2. In 45Ca2+ prelabeled SR, the maximal Ca2+ release was achieved at 10 microM IP3 incubated for 1 min. The release of Ca2+ was higher in SR of SHR than in the SR of WKY. IP3 stimulates Ca2-release from cardiac SR, and this release is greater in SHR than in WKY. However, it is uncertain whether this phenomenon plays a role in cardiac hypertrophy.

The accumulations of inositol-1,4,5-trisphosphate (IP3) and inositol-1,3,4,5-tetrakisphosphate (IP4) after hormonal stimulation may have a physiological role, possibly by alteration of Ca2+ levels in cardiac tissue. But the accumulation of inositol polyphosphate in a pathophysiological condition has not been studied. We investigated phosphatidylinositol-4,5-bisphosphate (PIP2) metabolism in hypertrophic cardiac myocytes, and clarified that the accumulations of IP3, IP4 and diacylglyceride after stimulation with norepinephrine were significantly enhanced in isolated myocytes from spontaneously hypertensive rat heart. Phospholipase C activity increased with age in SHRSP heart cells. These data suggest that PI turnover pathways, which can be mediated by both phosphatidylinositol-4,5-bisphosphate and diacylglyceride, may play an important role in development of hypertrophy in the hearts of rats with spontaneous hypertension.

BACKGROUND There have been no reports on the presence of the tissue renin-angiotensin system in the human heart, although the presence of angiotensinogen has been described in the animal heart. METHODS AND RESULTS To determine whether angiotensinogen is synthesized in the human heart, we examined angiotensinogen messenger RNA (mRNA) synthesis in autopsy hearts by using ribonuclease protection assay. As a result, angiotensinogen mRNA was detected in the atrial muscle, muscles of the conduction system, and the left ventricular wall. In the left ventricular wall, mRNA expression was more prominent in the subendocardial muscles than in the midcardial or epicardial muscles. Using a monoclonal antibody to human angiotensinogen in immunoblotting experiments, we detected two closely spaced bands at approximately 70 kd in the heart, which was quite consistent with the human angiotensinogen molecule. Immunohistochemical studies with this monoclonal antibody demonstrated intense immunoreactivity in the atrial muscles, the muscles of the conduction system, and those of the subendocardial layers. CONCLUSIONS We conclude that angiotensinogen was synthesized in the human heart. It was evident that the localization of angiotensinogen was not ubiquitous in the cardiac muscles, showing its predilection for the atrial muscles, muscles of the conduction system, and subendocardial layer of the left ventricle.

The aim of this study was to investigate the correlation between hypoxic myocardial cell injury and intracellular protease activity. Cardiac myocytes were isolated from neonatal rat hearts and cultured in Eagle's modified minimum essential medium. Myocytes were incubated in hypoxic conditions for 6 hours. The cell death rate during hypoxia rose to 80% after 6 hours. Extracellular protease activity was elevated to 4 units during hypoxia, much higher than the 0.7 units in aerobic states at 6 hours. This extracellular protease activity in hypoxic conditions was markedly inhibited by leupeptin and EDTA, and weakly inhibited by the cysteine protease inhibitor, NCO-700, but phenylmethyl sulfonyl fluoride did not inhibit the protease activity. To identify the protease activated during hypoxia, calpain-specific inhibitors were added to the incubation mixture. Calpain inhibitor 1 and calpastatin, an endogenous selective calpain inhibitor, markedly inhibited extracellular protease activity during hypoxia. NCO-700 also inhibited intracellular protease activity. NCO-700 reduced hypoxic cell death to 30% after 6 hours of hypoxy-genation. These observations indicate that calpain is activated during hypoxia and leads to irreversible cell membrane degradation after 6 hours of hypoxygenation.

The adaptor protein Crk mediates intracellular signaling related to cell motility and proliferation and is implicated in human tumorigenesis. The role of Crk in the growth of human sarcoma has remained unclear, however. The present study shows that Crk-induced activation of Src and subsequent signaling by p38 mitogen-activated protein kinase (MAPK) contribute to the enhanced proliferation of human synovial sarcoma cells. Depletion of Crk by RNA interference markedly inhibited proliferation of the synovial sarcoma cell lines HS-SYII, SYO-1, and Fuji as well as prevented anchorage-independent growth. Conversely, reconstitution with CrkII by authentic small interfering RNA–resistant Crk gene restored proliferation in Crk-silenced SYO-1 cells. Crk-depleted synovial sarcoma cells manifested enhanced transcriptional activity and expression of the p16INK4A gene, resulting in their accumulation in G1 phase of the cell cycle. In response to hepatocyte growth factor stimulation, Crk prominently induced the tyrosine phosphorylation of Grb2-associated binder 1 through activation of Src and focal adhesion kinase, and the Src family kinase inhibitor PP2 almost completely inhibited the proliferation of SYO-1 cells. Crk also induced the phosphorylation of p38 MAPK, and SB203580, a p38 MAPK–specific inhibitor, increased expression of p16INK4A gene in SYO-1 cells. Furthermore, SB203580 or depletion of p38 MAPK by small interfering RNA suppressed both the phosphorylation of Akt triggered by hepatocyte growth factor and the proliferation of SYO-1 cells. These results suggest that Crk promotes proliferation of human synovial sarcoma cells through activation of Src and its downstream signaling by a novel p38 MAPK-Akt pathway, with these signaling molecules providing potent new targets for molecular therapeutics. (Mol Cancer Res 2009;7(9):1582–92)

Angiogenesis is involved in various physiologic and pathological conditions, including tumor growth, and is tightly regulated by the orchestration of proangiogenic and antiangiogenic factors. Inhibition of vascular endothelial growth factor (VEGF), the best-established antiangiogenic treatment in cancer, has shown some effectiveness; however, the identification of novel regulators, whose function is independent of VEGF, is required to achieve better outcomes. Here, we show that transcription factor 8 (TCF8) is up-regulated in endothelial cells during angiogenesis, acting as a negative regulator. Furthermore, TCF8 is specifically expressed in the endothelium of tumor vessels. Tcf8-heterozygous knockout mice are more permissive than wild-type mice to the formation of tumor blood vessels in s.c. implanted melanoma, which seems to contribute to the more aggressive growth and the lung metastases of the tumor in mutant mice. Suppression of TCF8 facilitates angiogenesis in both in vitro and ex vivo models, and displays comprehensive cellular phenotypes, including enhanced cell invasion, impaired cell adhesion, and increased cell monolayer permeability due to, at least partly, MMP1 overexpression, attenuation of focal adhesion formation, and insufficient VE-cadherin recruitment, respectively. Taken together, our findings define a novel, integral role for TCF8 in the regulation of pathologic angiogenesis, and propose TCF8 as a target for therapeutic intervention in cancer. [Cancer Res 2009;69(4):1678–84]

Cell death during hypoxia rose to 80% after 6 h. Calpain activity increased to 4 units during hypoxia, much higher than the 0.7 units seen in aerobic condition at 6 h. This activity was markedly inhibited by calpain-specific inhibitor I ( n -acetyl-leucyle-leucyle-norleucinal). β-Adrenergic blocking agents and calcium antagonists suppressed the calpain activity and decreased cell death during hypoxia. On the other hand, α-adrenergic blocking agents did not affect calpain activity and cell death under hypoxic conditions. These results prove that β-adrenergic blocking agents and calcium antagonists prevent protein degradation during hypoxic cell injury.

We studied the effects of elastase on [3H]thymidine incorporation into aortic smooth muscle cells. When elastase was added to cultured aortic smooth muscle cells, [3H]thymidine incorporation was inhibited in a dose-dependent manner in the presence of fetal bovine serum. Elastase also inhibited this incorporation in cells treated with epidermal growth factor. Epidermal growth factor (50 ng/ml) stimulated thymidine incorporation, without elastase, but with the addition of 20 units/ml of elastase the incorporation was inhibited 70%. The incorporation of thymidine into cells treated with 50 ng/ml epidermal growth factor was also inhibited 50% by a low concentration of elastase (5 units/ml). These inhibitory effects on thymidine incorporation were also observed in cells stimulated with platelet-derived growth factor. Platelet-derived growth factor (20 units/ml) markedly stimulated thymidine incorporation into cells, and elastase inhibited its activity in a dose-dependent manner. These results suggest that elastase has the potential to prevent the development of atherosclerosis by inhibiting smooth muscle proliferation.

This study was undertaken to investigate the correlation between hypoxic cell injury and protease activity, as well as the effects of alpha 1-, and beta-adrenergic blocking agents and calcium antagonists during hypoxia. Cell death during hypoxia rose to 80% after 6h. Calpain activity increased to 4 units during hypoxia, much higher than the 0.7 units seen in aerobic condition at 6h. This activity was markedly inhibited by calpain-specific inhibitor I (n-acetyl-leucyle-leucyle-norleucinal). alpha 1-adrenergic blocking agents did not affect calpain activity and cell death under hypoxia. On the other hand, beta-adrenergic blocking agents and calcium antagonists suppressed the calpain activity and decreased cell death during hypoxia. These beta-adrenergic blocking agents and calcium antagonists also inhibited intracellular calcium-influx during hypoxia. These results suggest the beta-adrenergic receptor stimulation activates adenylate cyclase activity and enhances calcium-influx during hypoxia. The elevated intracellular calcium concentration then stimulates calpain activity under hypoxia. These results prove that beta-adrenergic blocking agents and calcium antagonists prevent protein degradation during hypoxic cell injury.

OBJECTIVE: For quick and stable identification of the primary motor area (PMA), diffusion tensor imaging (DTI) data were acquired and corticospinal tractography was mathematically visualized. METHODS: Data sets of DTI, anatomic magnetic resonance imaging, and functional magnetic resonance imaging with finger-tapping tasks were acquired during the same investigation in 30 patients with a brain lesion affecting the motor system. Off-line processing of DTI data was performed to visualize the corticospinal tract, placing a seed area in the cerebral peduncle of the midbrain, where the corticospinal tract is densely concentrated. Somatosensory evoked magnetic fields and intraoperative cortical somatosensory evoked potentials were recorded with electrical stimulation of the median nerve to confirm the results of the corticospinal tractography. RESULTS: Functional magnetic resonance imaging and somatosensory evoked magnetic fields failed to identify the PMA in eight patients (16.7%) and one patient (3.8%) investigated, respectively, because of cortical dysfunctions caused by brain lesions. DTI data were acquired within 3 minutes without patient tasks. Using the appropriate seed area and fractional anisotropy, corticospinal tractography successfully indicated the PMA location in all patients. The suspected PMA and central sulcus locations were confirmed by the cortical somatosensory evoked potentials. CONCLUSION: Corticospinal tractography enables identification of the PMA and is beneficial, particularly for patients who present with dysfunction of the PMA.

Hypertension is a major risk factor for atherosclerosis, and elevated pressure (i.e., mechanical pressure stresses) has been known to modulate vascular remodeling, possibly by affecting the tissue renin-angiotensin system.In the present study we applied pulsatile pressure to human aortic smooth muscle cells (HASMCs) and investigated whether mechanical pressure stress affects cell proliferation and/or the angiotensin-converting enzyme (ACE), and we tested whether the administration of an angiotensin II (AII) receptor blocker has a favorable effect.Three hours of pulsatile atmospheric pressure resulted in an approximately 8% increase in cell proliferation of human aortic smooth muscle cells. The cell surface ACE level, enzyme activity and mRNA expression were all elevated (37%, 110% and 17%, respectively) under pressurized conditions, and co-administration of AII reduced all these values. The reductions in these three parameters resulting from the administration of AII were all abolished by AII receptor blocker co-administration and values were increased (11%, 62% and 12%, respectively) under pressurized conditions. Pulsatile atmospheric pressure increased the amount of phosphorylated extracellular signal-regulated kinase (ERK) by approximately 54% in HASMCs. The administration of PD98059 (10 microM) resulted in a decrease in phosphorylated ERK and ACE activity in HASMCs compared to those of the pressurized control.From these observations, we conclude that pulsatile mechanical pressure is one of the mediators of ACE production in vascular smooth muscle cells and that AII receptor blocking may prevent negative feedback. The present findings may provide a potential therapeutical target beyond lowering blood pressure in hypertensive patients.

We studied the effects of atrial natriuretic factor (ANF) on the conversion of angiotensin I to angiotensin II. Pulmonary artery endothelial cells converted 1.22 nmol/min per dish [125I]angiotensin I to angiotensin II, but ANF suppressed the conversion by 0.475 nmol/min per dish. The maximum rate of inhibition of angiotensin converting enzyme (ACE) activity by ANF was 60% at 10(-6) mol/l ANF compared with control conditions. The amino acid fragments of ANF were studied to determine whether its specific structure was necessary for inhibiting ACE in endothelial cells. We found that atriopeptin II (fragment 5-27) inhibited ACE activity as much as ANF. Fragment 7-25 had the same rate of inhibition, but fragment 13-27 had no effect on the conversion of angiotensin I to angiotensin II. These results suggest that the amino acid sequence of Cys (7)-Cys (23) in ANF is important for the inhibition of ACE in pulmonary endothelial cells.

In the present experiment, we demonstrated that IP3 kinase activity was increased in SHRSP heart compared to WKY heart. IP3 kinase activity in the heart was highest in the cytosolic fraction in both SHRSP and WKY. Its activity progressively increased with age in 5- to 20-week SHRSP. The activity reached about three times the level of 5-week-old SHRSP in 40-week-old SHRSP. On the other hand, in WKY it was 1.3-fold at 40 weeks compared with that at 5 weeks. We determined the effect of divalent cations on IP3 kinase activity. Ca2+ stimulated its activity in a dose-dependent manner at 10(-9) to 10(-6) M. In SHRSP it was enhanced about 2.1-fold at 10(-6) M of Ca2+, but in WKY it was 1.5-fold at 1.0(-6) M of Ca2+. Mn2+ also stimulated IP3 kinase activity in both groups of animals, while, Fe2+, Zn2+, and Cu2+ inhibited IP3 kinase activity. In our experiment IP3 kinase activity was increased in SHRSP and its activity was markedly affected by divalent cations. These data suggest that the accumulations of IP3 and IP4 after hormonal stimulation play a physiologic role, possibly by alteration of Ca2+ levels in cardiac tissue.

We studied the effects of endothelin on the conversion of angiotensin I to angiotensin II in pulmonary artery endothelial cells. Endothelin had a novel effect on angiotensin I conversion. When endothelin was added to pulmonary artery endothelial cells, the conversion of angiotensin I to angiotensin II was enhanced about two-fold. The maximum stimulation was achieved at 10(-8) M of endothelin. This stimulatory effect was suppressed by angiotensin converting enzyme inhibitors such an enalapril. When the calcium antagonist, nifedipine, was incubated with 10(-8) M of endothelin, the conversion of angiotensin I to angiotensin II stimulated with endothelin was slightly suppressed by nifedipine. Enalapril (10(-6) M) completely inhibited the conversion of angiotensin I to angiotensin II in the presence of endothelin. These results suggest that endothelin may play an important role in regulating vascular tone by modulating the conversion of angiotensin I to angiotensin II.

We studied the effects of platelet activating factor (PAF) on angiotensin-converting enzyme (ACE). PAF (1 · 10 −10 to 1 · 10 −6 M) had a novel effect on angiotensin I conversion. Pulmonary artery endothelial cells converted 1 nmol/dish of 125 I-angiotensin I to angiotensin II in the absence of PAF. ACE activity was increased to 2.5 nmol/dish by the addition of 1 · 10 −6 M of PAF. To clarify the mechanism of this stimulatory effect of PAF on ACE, Ca 2+ influx and inositol 1,4,5-trisphosphate (IP 3 ) release in pulmonary artery endothelial cells were determined. PAF stimulated Ca 2+ influx in a dose-dependent manner. PAF also stimulated phospholipase C (PLC) activity and released IP 3 . To study the relationship between PLC activity and ACE activity, neomycin was added. The Ca 2+ influx and IP 3 release stimulated by 10 −6 M of PAF were suppressed by about 60–70%. ACE activity was also inhibited up to 70% in the presence of PAF (10 −10 − 10 −6 M) by 50 M of neomycin. These results suggest that ACE was stimulated by PAF, and that its activityl in endothelial cells may be mediated by the PI-turnover pathway via changes in PLC activity and IP 3 -mediated Ca 2+ release from intracellular stores.

Mechanical forces related to pressure and flow are important for cell hypertrophy and proliferation. There are still a few studies that examine responses of human vascular smooth muscle cells to pure pressure stress (transmural pressure). It is unclear as to which mechanisms are involved in cellular responses to pressure elevation. On the other hand, although the involvement of the local renin-angiotensin system (RAS) in pressure-induced responses was reported, the results were contradictory. It still remains to be determined whether RAS in human vascular smooth muscle cells is activated by pure pressure stress. We studied the upstream signal transduction events of extracellular signal kinase (ERK) in response to atmospheric pressure stress and involvement of angiotensin II in pressure-induced cell proliferation in human aortic smooth muscle cells (HASMC). A pressure-loading apparatus was set up to examine the effects of atmospheric pressure on human aortic smooth muscle cells. Pressure application of 160 mmHg for 3 h produced cell proliferation and activated ERK and c-JUN N-terminal kinase (JNK). ACE inhibitor suppressed all of them. ERK kinase (MEK) inhibitor also suppressed cell proliferation stimulated by pure pressure. The phosphorylated c-Src was increased by pure pressure stress. The treatment with c-Src kinase inhibitor suppressed pressure-induced proliferative response. In summary, our study found that ERK activation mediated pure pressure-induced proliferative response of HASMC. This activation was partly mediated by c-Src.

Contraction of skeletal muscle generates pressure stimuli to intramuscular tissues. However, the effects of pressure stimuli, other than those created by electricity or nerve impulse, on physiological and biochemical responses in skeletal muscles are unknown. The purpose of this study is to examine the effects of a pure pressure stimulus on metabolic responses in a skeletal muscle cell line. Atmospheric pressure was applied to L6 myoblasts using an original apparatus. Succinate dehydrogenase (SDH) activity was evaluated by colorimetric assay using tetrazolium monosodium salt. The amounts of 2-deoxy-[3H]glucose uptake and lactate release were measured. SDH activity was 2.6- to 2.9-fold higher in pressurized L6 cells than in nonpressurized L6 cells ( P < 0.01), and 2-deoxy-[3H]glucose uptake was 2.2-fold higher ( P < 0.001). In addition, the amount of released lactate decreased from 6.8 to 3.7 μmol/dish when pressure was applied ( P < 0.001). In contrast, the intracellular lactate contents of the pressurized cells were higher than those of nonpressurized cells ( P < 0.01). However, the total amount of released lactate and intracellular lactate was lower in the pressurized cells than in nonpressurized cells. These findings demonstrate that a pure pressure stimulus enhances aerobic metabolism in L6 skeletal muscle cells and raise the possibility that elevated intramuscular pressure during muscle activity may be an important factor in stimulating oxidative metabolic responses in skeletal muscles.

Lactate is formed and utilized continuously under fully aerobic conditions. Lactate is oxidized actively at all times, especially during exercise. Family of monocarboxylate transport proteins (MCTs) that are differentially expressed in cells and tissues accomplishes the facilitated transport of lactate across membranes. Previously we reported that there is MCT1 in blood circulation. We also reported the pressure stress stimulated cell proliferation in aortic smooth muscle cells (HASMC). In this experiment we attempted to prove the existence of MCT1 in HASMC and to clarify the effect of pressure stress on MCT1 localization in HASMC. We determined succinate dehydrogenase (SDH) activity as a marker of energy metabolism in cells. SDH activity was increased by pressure stress. Lactate enhanced the SDH activity under pressure stress (160 mmHg for 3 h) as dose dependent manner. On the other hand, lactate excretion was suppressed by the addition of lactate. We could detect MCT1 in the cytosolic and the membrane fractions of HASMC. The pressure stress increased MCT1 in the membrane fraction in the presence of extracellular lactate. In summary, we proved the existence of MCT1 in HASMC. Pressure stress changed the localization of MCT1. The increased membranous MCT1 may transport lactate for energy metabolism in cells.

Hypertension is a major risk factor for atherosclerosis and the genesis of cardiovascular and cerebrovascular diseases. Therefore, the protection of atherosclerosis progression is one of the purpose of an anti-hypertensive treatment in vascular system. Nitric oxide (NO)-releasing drugs have been reported to have an inhibitory effect on shear stress-induced extracellular signal-regulated kinase (ERK) activation in endothelial cells. For further understanding of the effects of these drugs, the present study focused on the effects on intracellular signal transduction and cell proliferation in cultured human aortic smooth muscle cells (HASMC) under high atmospheric pressure. Three hours of 160-mmHg atmospheric pressure resulted in an approximately 380% increase in cell proliferation compared to non-pressurized controls. Nipradilol (3,4-dihydro-8-(2-hydroxy-3-isopropylaminoproxy)-3-nitroxy-2 H -1-benzopyran) (10 −6 M) demonstrated approximately 40% reduction in cell proliferation compared to that shown by pressurized HASMC as a vehicle control. Three hours of 160-mmHg atmospheric pressure resulted in a 25% increase in the amount of activated ERKs. Nipradilol (10 −6 M) demonstrated approximately a 26% reduction in the amount of activated ERKs. NO x concentration under the presence of nipradilol (10 μM) with HASMC resulted in a 7.2 μM of NO production and was 2.4-fold more than that from no dug control (3.0 μM). An administration of L-NAME (10 −4 M) supplemented with Nipradilol (10 −6 M) did not show any significant effect on cell proliferation. From these observations, we concluded that nipradilol has an anti-proliferative effect on HASMC under high atmospheric pressure. Nipradilol may act as a nitric oxide inducer from HASMC and suspected to work as a supplement to mitigate the impaired endothelial cell function caused by hypertension.

Mechanical forces related to pressure and flow are important for cell hypertrophy and proliferation. We hypothesized the presence of mechanosensors that were solely sensitive to pure atmospheric pressure in the absence of shear and tensile stresses. A pressure-loading apparatus was set up to examine the effects of atmospheric pressure on human aortic smooth muscle cells (HASMC). Pressure application of 140 to 180 mmHg produced DNA synthesis in a pressure-dependent manner. In contrast, pressure of 120 mmHg or less produced no significant change. Pertussis toxin (PTx) completely inhibited the pressure-induced increase of DNA synthesis. Under the high pressure of 200 mmHg. Both extracellular signal-related kinase and c-Jun N-terminal kinase activities, but not p38 activity, were stimulated by pressure of more than 160 mmHg. ACE inhibitor inhibited cell proliferation under the pressure. But the addition of All on ACE inhibitor under the pressure could not recover the cell proliferation.

Recent reports have shown that angiotensin-converting enzyme inhibitors have a role in cardiac remodeling and have beneficial effects on congestive heart failure. But calcium antagonist therapy has been controversial in the treatment of congestive heart failure. The present study examined the effects of the calcium antagonist amlodipine on the morphological changes in the cardiac muscle cells and extracellular matrix and on progressive left ventricular dysfunction in cardiomyopathic hamsters. The effects of amlodipine were compared with enalapril.

To elucidate the intracellular function and localization of the heterotrimeric G-protein beta3 subunit (Gbeta3) in the heart, we studied the effects of subtype-specific beta-adrenergic receptor (beta-AR) stimulation on Gbeta3 localization using isoform-specific antibodies. The amount of Gbeta3 in the cytosol dramatically decreased in hearts perfused with isoproterenol (ISO) alone or ISO with ICI 118551, a beta2-AR antagonist. Propranolol or CGP 20712A, a beta1-AR antagonist, blocked the ISO-induced decrease in the Gbeta3 content of the cytosol. In contrast, Gbeta3 content of the membrane fraction significantly increased in hearts perfused with ISO alone or ISO with ICI 118551. We conclude that stimulation of the beta1-AR induces isoform-specific translocation of Gbeta3 from the cytosol to the membrane fraction in rat hearts.

Chronic mechanical stress of the heart secondary to arterial hypertension is a primary cause of left ventricular hypertrophy (LVH). The renin-angiotensin system (RAS) plays an important role in the cardiovascular system, regulating the expression of cardiac hypertrophy, in part, independent of the effects of systemic hypertension. A major component of RAS is angiotensin converting enzyme (ACE), which is upregulated in pressure overload-induced cardiac hypertrophy as well as heart failure. In a recent study, we found that the T allele of the M235T polymorphism of the angiotensinogen gene in sporadic hypertrophic cardiomyopathy (HCM) patients is associated with LVH. The present study was designed to assess the contribution of the polymorphisms of the angiotensin II type 1 receptor (AGT1R A1166C) genes on development of left ventricular hypertrophy. Patients with hypertensive LVH and relatives of HCM without manifesting the disease, showed higher C allele frequency compared to patients with HCM (11.3% vs 4.2%, chi 2 = 5.3, p < 0.05 and 10.5% vs 4.2%, chi 2 = 5.3, p < 0.05, respectively), but healthy controls did not (11.3% vs 7.5%, chi 2 = 1.42, NS and 10.5% vs 7.5%, chi 2 = 1.2, NS). The strong interaction between ACE I/D and AGT1R A1166C gene polymorphisms has been found in groups of relatives of HCM patients; odds ratio associated with ACE D allele was significant in subjects carrying the AGT1R C allele (OR = 7.3, 95% CI 1.6-33.1; chi 2 = 7.9, p < 0.02) compared with healthy subjects. We conclude that the molecular variant of the AGT1R A1166C gene is not contributing to the development of cardiac hypertrophy in hypertensive LVH and HCM patients, whereas carriers of both C and D alleles had a four-fold increase in the odds ratio for family history of HCM without manifesting the disease.

Angiotensinogen mRNA expression in human tissues was detected not only in the liver, but also in both atrial and ventricular heart tissues, suggesting that angiotensinogen is synthesized in the human heart. Angiotensinogen was present in the endocardial layer of the human left ventricle, rather than in the epicardial layer, and in the conduction system and right atrium. Furthermore, we found angiotensinogen to be widespread in the left ventricle of diseased hearts. We examined the involvement of collagen in the occurrence and progression of cardiomyopathy. In the early phase of cardiomyopathy, the extracellular matrix of the myocardium is rich in type III collagen, which is similar to immature tissues. In the later phase, the matrix resembles that of hard tissues in which collagen is mainly of type I and is insoluble. We also examined the relationship between angiotensin II and collagen synthesis. Previous studies have demonstrated that myocardial fibrosis accounts for impaired myocardial stiffness and ventricular dysfunction in hypertensive cardiac hypertrophy. Basal collagen synthesis in cardiac fibroblasts from spontaneously hypertensive rats (SHR) was 1.6 fold greater than that in Wistar-Kyoto rats. The responsiveness of collagen production to angiotensin II was significantly enhanced in SHR. This effect was angiotensin receptor specific because it was blocked by the competitive inhibitor. These results indicate angiotensin II may play an important role in collagen accumulation in hypertensive cardiac hypertrophy.

Recent reports have shown that angiotensin-converting enzyme inhibitors have a role in cardiac remodeling and have beneficial effects on congestive heart failure. Several studies have described alterations in sarcoplasmic reticulum gene expression in the failing heart. These results indicate that calcium homeostasis in myocytes may be disturbed in congestive heart failure. The present study examines the effects of long-term treatments with the angiotensin-converting enzyme inhibitor Enalapril and Ang II subtype 1 receptor antagonist TCV-116 on the morphological changes in the extracellular matrix, progressive left ventricular dysfunction in cardiomyopathic hamsters. Between age 5–20 weeks, 24 BIO53.58 hamsters (model of dilated cardiomyopathy) received 10mg/kg per day orally either of TCV-116 or no treatment. Between age 5–30 weeks, 24 BIO53.58 hamsters (model of dilated cardiomyopathy) received 20mg/kg per day orally either of Enalapril or no treatment. During the study period, cardiac function was assessed by echocardiography in a noninvasive manner. At 20 or 30 weeks of age, each heart was fixed with 10% formalin, embedded in paraffin, and serial sections were stained with Gomori’s aldehyde fuchsin using the Masson-Goldner method. High framerate ultrasonoscopic echocardiograms revealed that the left ventricular percent fractional shortening (%FS) tended to improve in the Enalapril group (22 ± 4% vs 20 ± 3%) and TCV-116 group (24 ± 4% vs 21 ± 4%). The fibrous tissue volume significantly decreased in Enalapril group (25.2 ± 0.5 mm3, P < 0.05) compared with the untreated group (27.6 ± 2.3mm3). TCV-116 did not significantly decrease the fibrous tissue volume. Enalapril can prevent cardiac remodeling, but TCV-116 is not as effective as Enalapril. Enalapril may nevertheless, suppress fibrosis.

The purpose of this study was to characterize the collagen in hereditary dilated cardiomyopathic hamster hearts, and to examine the participation of the collagen in the occurrence and progression of cardiomyopathy. BIO 53.58 hamsters (5, 10, 20 weeks old) were used as the model of dilated cardiomyopathy. Flb hamsters were used as controls. The collagen content was almost constant at any age in the Flb hamsters, but increased with age in BIO 53.58 hamsters. Type III collagen increased significantly in BIO 53.58 hamsters at 10 weeks. The acetic acid solubility of collagen decreased in BIO 53.58 hamsters as the fibrosis progressed, but was unchanged in controls. Reducible crosslinks showed a tendency to decrease progressively in BIO 53.58 hamsters. There were no differences between Flb and BIO 53.58 hamsters at 5 weeks, but its expression in BIO 53.58 hamsters at 10 and 20 weeks of age increased compared to Flb controls. These findings indicate that in the early phase of cardiomyopathy the extracellular matrix of the myocardium is rich in type III collagen. In the later phase, the matrix resembles that of hard tissues, whose collagen is mainly of type I collagen and is insoluble. These data suggest that the increased collagen synthesis may impair the cardiac function in the development of cardiomyopathy.