Overexpression of SMYD2 contributes to malignant outcome in gastric cancer.

BACKGROUND: SET and MYND domain-containing protein 2 (SMYD2) is a lysine methyltransferase for histone H3, p53 and Rb and inhibits their transactivation activities. In this study, we tested whether SMYD2 (1q42) acts as a cancer-promoting factor by being overexpressed in gastric cancer. METHODS: We analysed 7 gastric cancer cell lines and 147 primary tumor samples of gastric cancer, which were curatively resected in our hospital. RESULTS: SET and MYND domain-containing protein 2 was detected in these cell lines (five out of seven cell lines; 71.4%) and primary tumor samples (fifty-six out of one hundred and forty-seven cases; 38.1%). Knockdown of SMYD2 using specific small interfering RNA inhibited proliferation, migration and invasion of SMYD2-overexpressing cells in a TP53 mutation-independent manner. Overexpression of SMYD2 protein correlated with larger tumor size, more aggressive lymphatic invasion, deeper tumor invasion and higher rates of lymph node metastasis and recurrence. Patients with SMYD2-overexpressing tumours had a worse overall rate of survival than those with non-expressing tumours (P=0.0073, log-rank test) in an intensity and proportion score-dependent manner. Moreover, multivariate analysis demonstrated that SMYD2 was independently associated with worse outcome (P=0.0021, hazard ratio 4.25 (1.69-10.7)). CONCLUSIONS: These findings suggest that SMYD2 has a crucial role in tumor cell proliferation by its overexpression and highlight its usefulness as a prognostic factor and potential therapeutic target in gastric cancer.

Plasma microRNA profiles: identification of miR-25 as a novel diagnostic and monitoring biomarker in oesophageal squamous cell carcinoma.

BACKGROUND: Recent studies have demonstrated that microRNAs are stably detectable in plasma/serum because of their binding to specific proteins or being packaged in secretory particles. This study was designed to detect novel microRNAs in plasma for cancer detection and monitoring using microRNA array-based approaches in oesophageal squamous cell carcinoma (ESCC) patients. METHODS: Through the integration of two Toray 3D-Gene microRNA array-based approaches to compare plasma microRNA levels between ESCC patients and healthy volunteers and between preoperative and postoperative ESCC patients, we identified a novel plasma biomarker in ESCC. RESULTS: (1) Eight upregulated and common microRNAs (miR-15b, 16, 17, 25, 19b, 20a, 20b, and 106a) were selected using two high-resolution microRNA array approaches. (2) Test-scale analyses by quantitative RT-PCR validated a significant higher levels of plasma miR-19b (P=0.0020) and miR-25 (P=0.0030) in ESCC patients than controls. However, a significant correlation was observed between plasma miR-19b levels and concentrations of red blood cells (P=0.0073) and haemoglobin (P=0.0072). (3) miR-25 expression was found to be significantly higher in ESCC tissues (P=0.0157) and ESCC cell lines (P=0.0093) than in normal tissues and fibroblasts. (4) In a large-scale validation analysis, plasma miR-25 levels were significantly higher in 105 preoperative (P<0.0001) ESCC patients who underwent curative oesophagectomy and 20 superficial ESCC patients who underwent endoscopic resection (P<0.0001) than in 50 healthy volunteers. (5) Plasma miR-25 levels were significantly reduced in postoperative samples than in preoperative samples (P<0.0005) and were significantly increased during ESCC recurrences (P=0.0145). CONCLUSIONS: Plasma miR-25 might be a clinically useful biomarker for cancer detection and the monitoring of tumour dynamics in ESCC patients.

Alcohol consumption reduces ischemia-reperfusion injury by species-specific signaling in guinea pigs and rats.

We recently discovered that regular alcohol consumption reduces ischemia-reperfusion injury to the same degree as ischemic preconditioning in guinea pig hearts. Ischemic preconditioning, like this cardioprotective effect of alcohol, is mediated by adenosine signaling in guinea pigs. In rats, ischemic preconditioning may be mediated predominantly by alpha1-adrenergic signaling. To be certain that this protective effect of alcohol is a general biological response, we searched for alcohol's cardioprotection in rat and identified a potential signaling mechanism. Hearts isolated from alcohol-fed guinea pigs and rats were subjected to ischemia-reperfusion. Hearts from alcohol-fed animals showed greater recovery of left ventricular developed pressure than controls (guinea pigs, 46 vs. 29%; rats, 50 vs. 31%) and decreased myocyte necrosis assessed by creatine kinase release (guinea pigs, 204 +/- 42 vs. 440 +/- 70 U . ml-1 . g dry wt-1; rats 158 +/- 13 vs. 328 +/- 31 U . ml-1 . g dry wt-1). Adenosine receptor blockade [8-(p-sulfophenyl)theophylline] abolished alcohol's protection in guinea pig but not rat hearts. By contrast, alpha1-adrenergic blockade (prazosin) abolished alcohol's protection in rat but not guinea pig hearts. We conclude that regular alcohol consumption reduces ischemia-reperfusion injury and is mediated by species-specific signaling mechanisms. A major goal of cardiovascular research is to find a pharmacologically induced chronic state of preconditioning. Understanding the mechanisms of alcohol's cardioprotection against ischemia-reperfusion injury may aid in reaching this goal.

Activation of epsilon protein kinase C correlates with a cardioprotective effect of regular ethanol consumption.

In addition to decreasing the incidence of myocardial infarction, recent epidemiological data suggest that regular alcohol consumption improves survival after myocardial infarction. We recently found that chronic ethanol exposure induces long-term protection against cardiac ischemia-reperfusion injury, which improves myocardial recovery after infarction. Furthermore, this cardioprotection by ethanol is mediated through myocyte adenosine A1 receptors. We now determine the role of protein kinase C (PKC) in ethanol's protective effect against ischemia-reperfusion injury. Using perfused hearts of ethanol-fed guinea pigs, we find that improved contractile recovery and creatine kinase release after ischemia-reperfusion are abolished by PKC inhibition with chelerythrine. Western blot analysis and immunofluorescence localization demonstrate that regular ethanol consumption causes sustained translocation (activation) of epsilonPKC, but not delta or alphaPKC. This same isozyme is directly implicated in ischemic preconditioning's protection against ischemia-reperfusion injury. Our findings suggest (i) that regular ethanol consumption induces long-term cardioprotection through sustained translocation of epsilonPKC and (ii) that PKC activity is necessary at the time of ischemia to mediate ethanol's protective effect against ischemia-reperfusion injury. Studying this selective effect of ethanol on epsilonPKC activation may lead to new therapies to protect against ischemia-reperfusion injury in the heart and other organ systems.

Blockade of ATP-sensitive K+ channels attenuates preconditioning effect on myocardial metabolism in swine: myocardial metabolism and ATP-sensitive K+ channels.

OBJECTIVE: We investigated if blockade of ATP-sensitive K+ channels (KATP) abolishes the protective effect of ischemic preconditioning (IP) on myocardial metabolism and ischemia-induced reactive hyperemia (RH) in pigs. METHODS: IP was elicited by a single cycle of 5 min occlusion and 5 min reperfusion of coronary artery, followed by 15 min of test ischemia and 120 min of reperfusion. Vehicle or the ATP-sensitive K+ channels (KATP) blocker, glibenclamide (3 or 6 mg/kg; G3 or G6) was administered before IP (groups; IP, G3+IP, G6+IP). As respective controls, the same treatment was performed in groups without IP (groups; C, G3, G6). Tissue levels of ATP, creatine phosphate (CP) and intracellular pH (pHi) in the area at risk were measured by 31P-nuclear magnetic resonance spectroscopy. RH after 5 min of preconditioning ischemia was assessed by regional myocardial blood flow. RESULTS: ATP and pHi were preserved after 15 min of ischemia in the IP group [C/IP; ATP=57+/-4/76+/-10% of baseline, pHi=6.18+/-0.08/6.66+/-0.03, P<0.05, C vs. IP]. Both doses of glibenclamide completely abolished the ATP sparing effect of IP. The high dose completely abolished pHi preservation (G6+IP=6.33+/-0.06), while the low dose showed only a partial effect (G3+IP=6.48+/-0.03). Glibenclamide did not adversely affect myocardial metabolism in groups without IP. Glibenclamide attenuated RH after 5 min of ischemia by 30% in both subendocardium and subepicardium. CONCLUSIONS: Blockade of KATP abolished the preconditioning effect on myocardial metabolism, and partially attenuated post-ischemic reactive hyperemia in pigs. These results indicate that KATP activation might be involved in the mechanisms of these phenomena, reactive hyperemia is not sufficient to induce IP protection.

Inorganic phosphate and coronary perfusion pressure mediate contractile dysfunction during mild ischemia.

During mild graded ischemia in perfused rat hearts, we (V.M. Figueredo, R. Brandes, M. W. Weiner, B. M. Massie, and S. A. Camacho. J. Clin. Invest 90: 1794-1802, 1992) previously found a relationship between decreased left ventricular developed pressure (LVDP) and increased Pi, in which intracellular pH, cytosolic Ca2+ concentration ([Ca2+]i), ATP, and free-energy change of ATP hydrolysis were not altered enough to affect contractility. However, the contribution of decreased coronary perfusion pressure (CPP) to decreased LVDP could not be determined. Thus, in the present study, graded hypoxia in perfused rat hearts (95-37.5% O2) was used to increase Pi to similar levels produced during mild ischemia without altering CPP and minimizing changes of other potential mediators of contractile dysfunction. 31P-magnetic resonance spectroscopy and indo 1 fluorescence were used to assess energy metabolites and [Ca2+]i, respectively. The relationship between LVDP and Pi during graded hypoxia was fit to a monoexponential (LVDP = 105 x e-0.04Pi). These data were compared with the relationship of LVDP and Pi during mild ischemia (LVDP = 106 x e-0.08Pi) (V. M. Figueredo, R. Brandes, M. W. Weiner, B. M. Massie, and S. A. Camacho. J. Clin. Invest 90: 1794-1802, 1992). The exponential constant, which describes the effect of Pi on LVDP, was 50% lower during graded hypoxia relative to mild ischemia. This suggests that another mediator, which accounted for approximately 50% of the decrease of LVDP during mild ischemia, was not present during hypoxia. Because CPP decreased during ischemia but not hypoxia, these data suggest that CPP and Pi contribute similarly in mediating contractile dysfunction during mild ischemia.

Regular alcohol consumption mimics cardiac preconditioning by protecting against ischemia-reperfusion injury.

Epidemiologic studies indicate that long-term alcohol consumption decreases the incidence of coronary disease and may improve outcome after myocardial infarction. Attenuation of ischemia-reperfusion injury after myocardial infarction improves survival. This study investigates the possibility that alcohol consumption can improve survival after myocardial infarction by reducing ischemia-reperfusion injury. Hearts were isolated from guinea pigs after drinking ethanol for 3-12 weeks and subjected to global ischemia and reperfusion. Hearts from animals drinking ethanol showed improved functional recovery and decreased myocyte damage when compared with controls. Adenosine A1 receptor blockade abolished the protection provided by ethanol consumption. These findings indicate that long-term alcohol consumption reduces myocardial ischemia-reperfusion injury and that adenosine A1 receptors are required for this protective effect of ethanol. This cardioprotective effect of long-term alcohol consumption mimics preconditioning and may, in part, account for the beneficial effect of moderate drinking on cardiac health.

Preconditioning with 15-minute ischemia extends myocardial infarct size after subsequent 30-minute ischemia in rabbits.

Ischemic preconditioning (PC) induced by 1 cycle of 5-min coronary occlusion and 5-min reperfusion limits infarct size (IS) after 30-min sustained ischemia in rabbits. The shortest ischemic period that induces the PC effect in rabbits is 3 min. To establish the maximum ischemic period to induce a beneficial PC effect, we examined the effect of PC periods of 10 and 15 min on IS after sustained ischemia. The IS in control rabbit hearts after 30 min of sustained occlusion of the left anterolateral coronary artery and 48-h reperfusion was compared with that of hearts treated as follows before being subjected to PC: 5-min occlusion and 5-min reperfusion; 10-min occlusion and 5-min reperfusion; or 15-min occlusion and 5-min reperfusion. In addition, the IS after 15-min or 45-min occlusion and 48-h reperfusion was measured. There was no significant difference in blood pressure, heart rate, or area at risk (AAR) among the rabbits in 5 groups. The IS measured histologically was 40 +/- 4% of AAR in the control, 10 +/- 3% after 5-min PC, and 12 +/- 2% after 10-min PC. However, in the 15-min PC group, the IS was 77 +/- 4% of AAR, which was significantly larger than that of the controls, but similar to that of hearts subjected to 45-min ischemia and reperfusion (67 +/- 3%). As 15 min of preconditioning ischemia alone caused small infarcts (18 +/- 1% of AAR), the infarcts caused by sustained ischemia per se in the 15-min PC group was estimated to be 72 +/- 5% of AAR, which was still significantly higher than in the control groups. We conclude that the maximum period of preconditioning ischemia that induces cardioprotection in rabbits is 10 min. When the ischemic period is longer than this, the IS after sustained ischemia is increased rather than restricted. However, the infarcted size in the 15-min PC group was not higher than that in the group subjected to 45-min continuous ischemia. This may be a major limitation for any clinical application of PC.

Attenuation of postischemic reperfusion injury is related to prevention of [Ca2+]m overload in rat hearts.

Intracellular calcium overload has been implicated in postischemic reperfusion injury. In myocytes, mitochondrial free calcium concentration ([Ca2+]m), not cytosolic free calcium concentration ([Ca2+]c), overload is related to reoxygenation injury. We tested the hypothesis that [Ca2+]m, not [Ca2+]c, overload is an important mediator of reperfusion injury in whole hearts. [Ca2+]m and [Ca2+]c were assessed using indo 1 fluorescence in isolated rat hearts subjected to 45 min of ischemia and 20 min of reperfusion. Ruthenium red (RR), a selective inhibitor of mitochondrial calcium uptake at 0.025 microM, attenuated the increase of [Ca2+]m (4% RR vs. 57% control) over preischemic levels (230 +/- 10 nM) but did not affect the increase of systolic [Ca2+]c (990 +/- 100 nM RR vs. 1,010 +/- 130 nM control). This was associated with improved recovery of left ventricular developed pressure (61% RR vs. 37% control) and attenuation of the increase of diastolic pressure (34 mmHg RR vs. 47 mmHg control). Contractile recovery was related to the degree of [Ca2+]m overload in both control and RR hearts (r2 = 0.47, P = 0.001). This study is the first to demonstrate that [Ca2+]m, and not [Ca2+]c, overload is related to reperfusion injury in intact beating hearts.

Cytosolic and mitochondrial [Ca2+] in whole hearts using indo-1 acetoxymethyl ester: effects of high extracellular Ca2+.

Assessment of free cytosolic [Ca2+] ([Ca2+]c) using the acetoxymethyl ester (AM) form of indo-1 may be compromised by loading of indo-1 into noncytosolic compartments, primarily mitochondria. To determine the fraction of noncytosolic fluorescence in whole hearts loaded with indo-1 AM, Mn2+ was used to quench cytosolic fluorescence. Residual (i.e., noncytosolic) fluorescence was subtracted from the total fluorescence before calculating [Ca2+]c. Noncytosolic fluorescence was used to estimate mitochondrial [Ca2+]. In hearts paced at 5 Hz (N = 17), noncytosolic fluorescence was 0.61 +/- 0.06 and 0.56 +/- 0.07 of total fluorescence at lambda 385 and lambda 456, respectively. After taking into account noncytosolic fluorescence, systolic and diastolic [Ca2+]c was 673 +/- 72 and 132 +/- 9 nM, respectively, noncytosolic [Ca2+] was 183 +/- 36 nM and increased to 272 +/- 12 when extracellular Ca2+ was increased from 2 to 6 mM. This increase in noncytosolic [Ca2+] was inhibited by ruthenium red, a blocker of Ca2+ uptake by mitochondria. We conclude that cytosolic and mitochondrial [Ca2+] can be determined in whole hearts loaded with indo-1 AM by using Mn2+ to quench cytosolic fluorescence.

Cardiovascular risk factors in diabetic patients undergoing continuous ambulatory peritoneal dialysis.

To determine the impact of continuous ambulatory peritoneal dialysis (CAPD) on cardiovascular risk factors in diabetic patients, we evaluated serum lipid profiles and plasma levels of coagulation and fibrinolysis parameters in 23 diabetic patients on long-term CAPD (aged 55 +/- 14 years, mean +/- SD), and compared them with those of diabetic patients undergoing hemodialysis (n = 62, 56 +/- 10 years) or kidney transplantation (n = 14, 43 +/- 14 years), and 40 normal subjects (39 +/- 10 years). All of the parameters were compared using analysis of covariance to adjust for the difference in age among the four groups in males and females separately. In the male CAPD patients, there were no significant differences in the serum concentrations of lipids, lipoproteins, and apolipoproteins. In contrast, in the female CAPD patients, the levels of triglyceride and apolipoprotein (apo) B and the low-density lipoprotein (LDL) cholesterol/ high-density lipoprotein (HDL) cholesterol ratio were significantly higher than those in the normal females. Lipoprotein (a) did not differ significantly among the four male and female groups. The plasma levels of fibrinogen and von Willebrand factor were higher both in the male and in the female CAPD patients than in the other corresponding groups. There was no significant difference in the levels of plasminogen activator inhibitor-1 among the four groups. In conclusion, CAPD is associated with a more atherogenic lipid profile than are hemodialysis and kidney transplantation in female diabetic patients, but not in male diabetic patients. Both male and female diabetic patients on CAPD have a hypercoagulability state but not a decreased fibrinolysis state.

Transient adenosine infusion before ischemia and reperfusion protects against metabolic damage in pig hearts.

We investigated whether transient adenosine (Ado) infusion before ischemia had the same effect on myocardial metabolism and function as ischemic preconditioning (IP). The control (C) group underwent 15 min of coronary artery occlusion followed by 120 min of reperfusion. The Ado group received a 15-min infusion of Ado (200 micrograms.kg-1.min-1) into the left atrium starting 20 min before ischemia. IP was elicited by two cycles of 5-min ischemia and 5-min reperfusion. In the area at risk, tissue levels of ATP, creatine phosphate (CP), and intracellular pH (pHi) were serially measured by 31P-nuclear magnetic resonance spectroscopy in 10 pigs from each group, and percent segment shortening (%SS) was measured in 7 pigs from each group. ATP and pHi were preserved after 15 min of ischemia in both Ado and IP groups [ATP = 64 +/- 7, 76 +/- 6, and 74 +/- 9% of baseline; pHi = 6.35 +/- 0.19, 6.54 +/- 0.11, and 6.64 +/- 0.11 in C, Ado, and IP groups, respectively (P < 0.05, Ado and IP vs. C)]. During reperfusion, ATP was restored progressively in both groups [71 +/- 7, 90 +/- 8, and 91 +/- 9% of baseline at 120 min of reperfusion in C, Ado, and IP groups, respectively (P < 0.05, Ado and IP vs. C)]. However, in contrast to the IP group, CP was not preserved during 15-min ischemia nor did it show persistent overshoot during reperfusion in the Ado group. There were no significant differences in %SS during ischemia and reperfusion among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Ischemic preconditioning elevates cardiac stress protein but does not limit infarct size 24 or 48 h later in rabbits.

We investigated whether ischemic preconditioning (PC) produced a second window of protection by delayed synthesis of cardioprotective proteins. Anesthetized open-chest rabbits were subjected to 30 min of coronary occlusion and 3 h of reperfusion. PC was elicited by 5 min of ischemia and was separated from sustained ischemia by 5 min, 2 h, or 24 h of reperfusion. Infarct size (% area at risk) was markedly limited by PC with 5 min of reperfusion when compared with controls (13.3 +/- 2.5 vs. 46.8 +/- 7.0%; P < 0.05). This protective effect was lost when the interval between PC and sustained ischemia was extended to 2 h (47.8 +/- 4.8%; P = NS vs. control) and did not reoccur even when it was extended to 24 h (44.2 +/- 6.5%; P = NS vs. sham-operated control). To potentiate induction of heat shock proteins (HSPs), a PC protocol involving four 5-min episodes of ischemia and reperfusion was also used and was separated from sustained ischemia by 24 or 48 h of reperfusion. However, neither of these protocols was protective, and limitation of infarct size was not observed (55.5 +/- 5.9 and 53.4 +/- 6.5% in 24 and 48 h of reperfusion, respectively; P = NS vs. corresponding sham-operated control). Myocardial expression of HSPs was examined using a monoclonal antibody against 72- to 73-kDa HSP in additional rabbits. Immunoreactivity was observed in the myocardium at 24 and 48 h after PC, but not immediately after PC.(ABSTRACT TRUNCATED AT 250 WORDS)

Dropout of young non-insulin-dependent diabetics from diabetic care.

We investigated the follow-up status and prognosis of 109 patients with non-insulin-dependent diabetes mellitus aged from 10 to 19 years old (66 males and 43 females). Patients who had not attended hospital for at least 20 months up to the end of September 1990 were regarded as defaulters, and were surveyed by questionnaire. There were 62 defaulters (56.9%) among the 109 patients originally enrolled in diabetes care. The defaulters had a significantly higher body mass index (both males and females), mean arterial blood pressure, and fasting blood glucose level than the patients still attending the diabetes clinic, as well as a significantly worse lipid profile. The main reason given for non-attendance was a busy schedule. Compared with patients attending the diabetes clinic, a lower percentage of the defaulters remained on a diet or took regular exercise. Rapid eating was more common among the defaulters than the attendees (92.9% vs. 60%, P = n.s.). Thus, the lifestyle of the defaulters seemed to be undesirable for young diabetic patients. These findings emphasize the importance of effective education and follow-up for young obese patients with non-insulin-dependent diabetes mellitus.

Ventricular expression of brain natriuretic peptide in hypertrophic cardiomyopathy.

BACKGROUND: Brain natriuretic peptide (BNP), as a cardiac hormone, is expressed together with atrial natriuretic peptide (ANP) in the ventricles in congestive heart failure. However, the ventricular expression of BNP in hypertrophic cardiomyopathy (HCM) with normal systolic function is still unclear. METHODS AND RESULTS: The study population consisted of 39 HCM patients with asymmetric septal hypertrophy and 10 control subjects without any specific cardiac disease. Eleven cases of HCM were obstructive (HOCM), and the other 28 cases were nonobstructive (HNCM). All of these patients had a normal ejection fraction. Immunohistochemical analysis of endomyocardial biopsy specimens with specific monoclonal antibodies showed BNP immunoreactivity in the HOCM group (5/10, 50%) but not in the HNCM group (0/22) or in control subjects (0/5). In HOCM, left ventricular end-diastolic pressure was significantly higher in the BNP-positive patients than the BNP-negative patients. Histological changes such as myocardial fiber disarray, hypertrophy of myocytes, and fibrosis were greater in BNP-positive patients than BNP-negative patients in HCM. However, the expression had no significant relation with other clinical parameters. The elevation of the BNP plasma level versus control subjects was marked in both HOCM (85-fold) and HNCM (23-fold). By contrast, the elevation of the ANP plasma level versus control subjects was mild in HOCM (5.7-fold) and HNCM (4.2-fold). The ratio of BNP level to ANP level was higher in HOCM (4.16) than in HNCM (1.46) and control subjects (0.28), and it was higher than the ratio previously reported for severe congestive heart failure (1.72). CONCLUSIONS: These findings suggest that BNP is expressed in the ventricular myocytes of HCM with normal systolic function. In HOCM, ventricular expression of BNP may be augmented in response to both obstruction and diastolic dysfunction.

Preconditioning improves energy metabolism during reperfusion but does not attenuate myocardial stunning in porcine hearts.

BACKGROUND: It has been reported that a brief period of coronary occlusion and reperfusion slows the rate of ATP depletion during subsequent sustained ischemia as well as limiting infarct size. However, it has not yet been determined whether ischemic preconditioning also has an effect on the functional and metabolic recovery of stunned myocardium. Our study was designed to address this problem. METHODS AND RESULTS: Farm pigs were anesthetized with fluothane and randomly assigned to either a control group or a preconditioned group. The control group (n = 15) underwent 15 minutes of coronary occlusion followed by 120 minutes of reperfusion. The preconditioned group (n = 14) underwent two episodes of 5-minute occlusion and 5-minute reperfusion followed by 15 minutes of occlusion and 120 minutes of reperfusion. This protocol was designed to exclude the stunning effect of the preconditioning procedure itself as much as possible besides preconditioning the heart. A pair of ultrasonic crystals was implanted in the area at risk perfused by the left anterior descending coronary artery. 31P-nuclear magnetic resonance spectroscopy and sonomicrometry were performed alternately. Regional myocardial blood flow (RMBF) was determined with colored microspheres. At 15 minutes of sustained ischemia, phosphocreatine (Pcr), ATP, and intracellular pH were significantly better preserved in the preconditioned group (Pcr: control/preconditioned, 1 +/- 1%/14 +/- 1%; ATP:control/preconditioned, 66 +/- 2%/74 +/- 2%; pH:control/preconditioned, 6.32 +/- 0.07/6.52 +/- 0.05; P < .05). After reperfusion, ATP increased progressively and was almost normalized at 120 minutes of reperfusion in the preconditioned group (control/preconditioned, 73 +/- 4%/95 +/- 3%; P < .05). Overshoot of Pcr (which indicates that the energy generating system is operating better than energy utilizing system) persisted in preconditioned hearts but disappeared rapidly in controls (control/preconditioned, 104 +/- 3%/130 +/- 3% after 120 minutes of reperfusion). There was no significant difference in percent segment shortening (%SS), RMBF, and hemodynamics between the two groups throughout the experiment (%SS: control/preconditioned, 29.8 +/- 5.9%/28.8 +/- 6.3% of baseline after 120 minutes of reperfusion). CONCLUSIONS: Preconditioning improves energy metabolism during reperfusion, although it does not attenuate myocardial stunning for at least 2 hours after reperfusion.

Dobutamine prevents both myocardial stunning and phosphocreatine overshoot without affecting ATP level.

Catecholamines can overcome myocardial stunning. However, a previous report on energy metabolism in stunned myocardium during catecholamine infusion was based on the conventional biochemical methods which might affect contractile function. Twenty farm pigs were anesthetized and underwent 15 min coronary artery occlusion and 2 h reperfusion. Ten pigs were given 10 micrograms/kg/min dobutamine from immediately after and throughout the reperfusion (dobutamine group). The other ten pigs were given saline (control group). Phosphorus-31 magnetic resonance spectroscopy and sonomicrometry were done alternately. Dobutamine improved percent segment shortening after reperfusion (control/dobutamine = 3.8%-5.7%/11.7%-13.4%; P < 0.01). At 15 min ischemia, adenosine triphosphate (ATP) decreased (control/dobutamine = 72 +/- 8%/73 +/- 10%, n.s.), and remained depressed after reperfusion in both groups. After reperfusion, phosphocreatine (PCr) returned to and maintained the preischemic value in the dobutamine group, while in the control group, PCr overshoot (112 +/- 5%) was observed. Except for the presence and absence of PCr overshoot, there was no significant difference of ATP and PCr between the two groups, although rate pressure product was significantly higher in the dobutamine group than in the control group. Regional myocardial blood flow after reperfusion was significantly higher in the dobutamine group. Dobutamine may improve "stunning" through effective improvement of energy utilization and production, indicated by the disappearance of PCr overshoot and maintained ATP level.

Histologic studies in percutaneous transluminal coronary angioplasty for chronic total occlusion: comparison of tapering and abrupt types of occlusion and short and long occluded segments.

OBJECTIVES: The purpose of this study was to examine the histologic-angiographic correlates of chronic total coronary occlusion and to explain why a tapering type of occlusion and short occluded segments are favorable for percutaneous transluminal coronary angioplasty. BACKGROUND: Coronary angioplasty is less successful for vessels with chronic total occlusion than for highly stenotic but patent vessels. Several clinical and angiographic factors determining the rate of initial success have been investigated, but the underlying histologic features are not clear. METHODS: Ten autopsy hearts that showed chronic total coronary occlusion on cineangiography performed < or = 3 months before death were selected. In all, the estimated duration of occlusion was > 1 year. At autopsy, postmortem angiography was performed and hearts were fixed with 10% buffered formalin. Occluded segments were sectioned transversely and serially into slices 10 microns thick. Every five slices were stained in hematoxylin-eosin and elastic van-Gieson. RESULTS: Ten hearts with chronic total coronary occlusion were angiographically classified into five with a tapering and five with an abrupt type of occlusion and seven with a short (< or = 15 mm) and three with a long (> 15 mm) occluded segment. Histologically, the occluded segment was composed of loose or dense fibrous tissue, atheroma, small vascular channels and calcified tissue. Reconstruction of the serial preparations showed that small lumen recanalized areas (diameter 160 to 230 microns) with surrounding loose fibrous tissue penetrated the occluded segment in four hearts with occlusion of the tapering type and a short occluded segment. In these four cases, the lack of anterograde flow on cineangiography could be explained by the presence of rich collateral flow. In three cases of the abrupt type of occlusion with a short occluded segment, a mass of loose fibrous tissue penetrated the occluded segment. In hearts with a long occluded segment (one with a tapering type of occlusion and two with an abrupt type), there was no recanalization and loose fibrous tissue was dispersed in the occluded segment. CONCLUSIONS: Chronic total coronary occlusion of the tapering type or with a short occluded segment, or both, is possibly favorable for angioplasty, because small lumen recanalized areas or loose fibrous tissue penetrates the occluded segment and may form a route for successful angioplasty.

Adhesive strength between teeth and resin cements for porcelain laminate veneer.

We performed an experiment on adhesive strength between teeth and resin cements for porcelain laminate veneer. A compression shear test was performed using three types of resin cement in extracted human anterior teeth. In dentin, the effects of various surface treatment methods were also evaluated. All three types of resin cement showed high adhesive strengths to enamel, but low adhesive strengths to dentin that were less than 1/2 of those to enamel. Treatment of the dentin surface with both a surface treatment agent and primer significantly increased adhesive strength.