TRAP-induced PAR1 expression with its mechanism during AMI in a rat model.

BACKGROUND AND OBJECTIVE: Protease-activated receptor 1 (PAR1) is crucial in individuals with acute myocardial infarction (AMI). The continuous and prompt PAR1 activation mainly dependent on PAR1 trafficking is essential for the role of PAR1 during AMI in which cardiomyocytes are in hypoxia. However, the PAR1 trafficking in cardiomyocytes specially during the hypoxia is still unclear. METHODS AND RESULT: A rat AMI model was created. PAR1 activation with thrombin-receptor activated peptide (TRAP) had a transient effect on cardiac function in normal rats but persistent improvement in rats with AMI. Cardiomyocytes from neonatal rats were cultured in a normal CO2 incubator and a hypoxic modular incubator chamber. The cells were then subjected to western blot for the total protein expression and staining with fluorescent reagent and antibody for PAR1 localization. No change in total PAR1 expression following TRAP stimulation was observed; however, it led to increased PAR1 expression in the early endosomes in normoxic cells and decreased expression in the early endosomes in hypoxic cells. Under hypoxic conditions, TRAP restored the PAR1 expression on both cell and endosomal surfaces within an hour by decreasing Rab11A (8.5-fold; 179.93 ± 9.82% of the normoxic control group, n = 5) and increasing Rab11B (15.5-fold) expression after 4 h of hypoxia. Similarly, Rab11A knockdown upregulated PAR1 expression under normoxia, and Rab11B knockdown downregulated PAR1 expression under both normoxic and hypoxic conditions. Cardiomyocytes knocked out of both Rab11A, and Rad11B lost the TRAP-induced PAR1 expression but still exhibited the early endosomal TRAP-induced PAR1 expression under hypoxia. CONCLUSIONS: TRAP-mediated activation of PAR1 in cardiomyocytes did not alter the total PAR1 expression under normoxic conditions. Instead, it triggers a redistribution of PAR1 levels under normoxic and hypoxic conditions. TRAP reverses the hypoxia-inhibited PAR1 expression in cardiomyocytes by downregulating Rab11A expression and upregulating Rab11B expression.

Detection of Acute Myocardial Infarction in a Pig Model Using the SAN-Atrial-AVN-His (SAAH) Electrocardiogram (ECG), Model PHS-A10, an Automated and Integrated Signals Recognition System.

BACKGROUND The aim of this study was to compare the use of the standard 12-lead electrocardiogram (ECG) with the SAN-Atrial-AVN-His (SAAH) ECG (Model PHS-A10), a new automated and integrated signals recognition system that detects micro-waveforms within the P, QRS, and T-wave, in a pig model of acute myocardial infarction (MI). MATERIAL AND METHODS Six medium-sized domestic Chinese pigs underwent general anesthesia, and an angioplasty balloon was placed and dilated for 120 minutes in the first diagonal coronary artery arising from the left anterior descending (LAD) coronary artery. A standard ECG and a SAAH ECG (Model PHS-A10) were used to evaluate: 1) the number of wavelets in ST-T segment in lead V5; 2) the duration of the repolarization initial (Ri), or duration of the wavelets starting from the J-point to the endpoint of the wavelets in the ST interval; 3) the duration of the repolarization terminal (Rt), of the wavelets, starting from the endpoint of the wavelets in the ST interval to the cross-point of the T-wave and baseline; 4) the ratio Ri: Rt. RESULTS Following coronary artery occlusion, duration of Ri and Ri/Rt increased, and Rt decreased, which was detected by the SAAH ECG (Model PHS-A10) within 12 seconds, compared with standard ECG that detected ST segment depression at 24 seconds following coronary artery occlusion. CONCLUSIONS The findings from this preliminary study in a pig model of acute MI support the need for clinical studies to evaluate the SAAH ECG (Model PHS-A10) for the early detection of acute MI.

Prewire channel stent: a novel stent for bifurcation lesions in a pig model.

AIMS: Avoiding side branch occlusion is challenging when treating bifurcation lesions. A newly designed stent system called the prewire channel stent (PWCS) with a side channel positioned between the metallic mesh material and the balloon is introduced. We aimed to compare the time taken to position the PWCS against that for a conventional stent. METHODS AND RESULTS: The PWCS and a conventional stent were used in a pig model. The time taken from the starting point with the stent outside the body to reaching the bifurcation of the vessel ready for further procedures such as balloon dilatation through the stent mesh opening and double kissing balloon technique, etc., was compared in the conventional stent and PWCS groups. The time taken in the PWCS stent group included the time from sending the stent from outside the body to the desired position of the bifurcation of the vessels of the heart, releasing the stent and pulling back the balloon (SB time). The time taken in the conventional stent included the time from sending the stent from outside the body to the desired position of the bifurcation of the vessels of the heart, releasing the stent, pulling back the balloon (SB time), and wire exchange (WE time). The SB times for the PWCS and the conventional stent groups were not different (28.5±3.8 vs. 25.25±0.75 seconds, n=4). The PWCS group did not have "wire exchange," and had no WE time, which was 28.5±5.7 seconds in the conventional stent group. The total time spent in the PWCS group was 28.5±3.8 seconds, which was shorter than the 53.75±6.2 seconds (n=4, p<0.05) in the conventional stent group. CONCLUSIONS: The PWCS makes "wire exchange" in the side branch (SB) unnecessary and it can be as easily manipulated as a conventional stent.

Factors Influencing Difficulty of Laparoscopic Abdominoperineal Resection for Ultra-Low Rectal Cancer.

PURPOSE: Our current study was conducted to identify patients' anatomic, pathologic, and clinical factors to predict difficulty of performing laparoscopic abdominoperineal resection for ultra-low rectal cancer. MATERIALS AND METHODS: Records of 117 consecutive patients with rectal cancer 2 to 5 cm from the anal verge were retrospectively reviewed. Using univariate and multivariate linear or logistic regression models, standardized operative time and blood loss, as well as postoperative morbidity were utilized as endpoints to screen patients' multiple variables to predict operative difficulty. RESULTS: Multivariate linear regression analysis showed body mass index (BMI) (estimate=0.07, P=0.0056), interspinous distance (estimate=-0.02, P=0.0011), tumor distance from anal verge (estimate=-0.17, P=0.0355), prior abdominal surgery (estimate=0.51, P=0.0180), preoperative chemoradiotherapy (estimate=0.67, P=0.0146), and concurrent diseases (hypertension and/or diabetes mellitus) (estimate=0.49, P=0.0122) are predictors for standardized operative time. Age (estimate=0.02, P=0.0208) and concurrent diseases (estimate=0.43, P=0.0476) were factors related to standardized blood loss. BMI (estimate=0.15, P=0.0472) was the only predictor for postoperative morbidity based on logistic regression analysis. CONCLUSIONS: Age, BMI, interspinous distance, tumor distance from anal verge, prior abdominal surgery, preoperative chemoradiotherapy, and concurrent diseases influence the difficulty of performing laparoscopic abdominoperineal resection for ultra-low rectal cancer. Standardized operative time allows researchers to amass samples by pooling data from all published studies, thus building reliable models to predict operative difficulty for clinical use.

C-Reactive Protein and Inflammatory Cytokines during Percutaneous Coronary Intervention.

BACKGROUND: C-reactive protein (CRP) is significantly associated with cardiovascular diseases; however, whether CRP plays a causal role in coronary artery disease has yet to be determined. In addition, the relationship between CRP, atherosclerosis, and inflammation remains controversial. METHODS AND RESULTS: Serum interleukin (IL)-6, IL-1ß, and CRP levels were determined in 160 patients at time points around percutaneous coronary intervention (PCI) with drug-eluting stent implantation. The levels were found to be at peak at 24 h post-PCI and gradually declined to the level before PCI at day 30 post-PCI. These inflammation markers around PCI have no statistical difference in the different postdilation pressures (≤14, 14-18, and ≥18 atm) and stent number (1 and ≥2 stents) groups. Treatment of cultured human vascular smooth muscle cells (VSMCs) with a combination of IL-6 and IL-1ß at concentrations associated with PCI did not result in any significant change in the CRP mRNA levels. The IL-6-augmented CRP expression in human internal mammary arteries (IMAs) stretched with a mechanical strength of 3 g was blocked by the nuclear factor-κB (NF-κB) peptide inhibitor SN50 and not by the inactive SN50 analog SN50M. IL-6 treatment increased NF-κB activity in human IMAs stretched with 3 g, and this effect was further blocked by stretch-activated channel (SAC) inhibitors (streptomycin or GdCl3) and SN50. CONCLUSIONS: The current study provides evidence that increased serum IL-6, IL-1ß, and CRP levels around PCI are not different between different postdilation pressure and stent number groups. The combination of IL-6 and IL-1ß at concentrations associated with PCI cannot induce CRP expression in human VSMCs, but they can augment mechanical strain-induced CRP synthesis via the SAC-NF-κB pathway in human IMAs.

Factors Predicting Difficulty of Laparoscopic Low Anterior Resection for Rectal Cancer with Total Mesorectal Excision and Double Stapling Technique.

BACKGROUND: Laparoscopic sphincter-preserving low anterior resection for rectal cancer is a surgery demanding great skill. Immense efforts have been devoted to identifying factors that can predict operative difficulty, but the results are inconsistent. OBJECTIVE: Our study was conducted to screen patients' factors to build models for predicting the operative difficulty using well controlled data. METHOD: We retrospectively reviewed records of 199 consecutive patients who had rectal cancers 5-8 cm from the anal verge. All underwent laparoscopic sphincter-preserving low anterior resections with total mesorectal excision (TME) and double stapling technique (DST). Data of 155 patients from one surgeon were utilized to build models to predict standardized endpoints (operative time, blood loss) and postoperative morbidity. Data of 44 patients from other surgeons were used to test the predictability of the built models. RESULTS: Our results showed prior abdominal surgery, preoperative chemoradiotherapy, tumor distance to anal verge, interspinous distance, and BMI were predictors for the standardized operative times. Gender and tumor maximum diameter were related to the standardized blood loss. Temporary diversion and tumor diameter were predictors for postoperative morbidity. The model constructed for the operative time demonstrated excellent predictability for patients from different surgeons. CONCLUSIONS: With a well-controlled patient population, we have built a predictable model to estimate operative difficulty. The standardized operative time will make it possible to significantly increase sample size and build more reliable models to predict operative difficulty for clinical use.

Comparison of perioperative outcomes between laparoscopic and open surgery for mid-low rectal cancer with total mesorectal excision following neoadjuvant chemoradiotherapy.

OBJECTIVE: The objective of our study was to determine the feasibility and safety of laparoscopic total mesorectal excision (TME) for mid-low rectal cancer following neoadjuvant chemoradiotherapy (nCRT). METHODS: We retrospectively reviewed the records of 172 patients with locally advanced rectal cancer who underwent laparoscopic (n = 75) or conventional open (n = 97) surgery with TME following nCRT from June 2009 to October 2015. Perioperative outcomes and related clinical variables were collected and statistically analyzed. RESULTS: Our results showed that patients who underwent laparoscopic surgery had significantly less blood loss and shorter time to pass first flatus and to start a liquid diet compared to those on open surgery. However, other perioperative outcomes, including operative times, postoperative morbidity rates, number of lymph nodes harvested, and sphincter preservation rates, were not significantly different between the two groups. After controlling for surgical approaches, we found that age, gender, tumor stages, and tumor distance to anal verge were significantly correlated with operative times in both groups. Likewise, age, body mass index, tumor T stages, and tumor distance to anal verge were predictors for postoperative morbidity in both groups. CONCLUSIONS: We concluded that laparoscopic TME following nCRT is feasible and safe for patients with mid-low rectal cancer. Furthermore, tumor distance to anal verge and age are two important determinants of both operative times and postoperative morbidity, regardless of surgical option.

Effects of thrombin and thrombin receptor activation on cardiac function after acute myocardial infarction.

Thrombin and thrombin receptor activation impact cardiomyocyte contraction and ventricular remodeling. However, there is some controversy regarding their effects in cardiac function, especially in cardiac dysfunction after acute myocardial infarction (AMI). A rat AMI model was created by left coronary artery ligation (LCA). Cardiac functional parameters, including the maximum left ventricular (LV) systolic pressure (LVSPmax), LV end-diastolic pressure (LVEDP), and the rise and fall rates in LV pressure (dp/dt max and dp/dt min, respectively), were measured. Hirudin decreased cardiac function within 120 minutes after AMI, whereas treatment with thrombin receptor-activating peptide (TRAP) reversed this hirudin-induced decrease in cardiac function. The mRNA and protein expression levels of inositol 1,4,5-trisphosphate receptor (IP3R) subtypes in infarct area tissues were analyzed by reverse transcription-polymerase chain reaction and immunoreaction. Hirudin decreased the expression levels of IP3R-1, -2, and -3 in the infarct area for up to 40 minutes after AMI, whereas TRAP treatment reversed these hirudin-induced effects. Treatment with the IP3R antagonist 2-aminoethoxydiphenyl borate (2.5 mg/kg) eliminated the effect of TRAP on the hirudin-induced decrease in cardiac function after AMI. Finally, TRAP increased the maximum binding capacity of the three IP3R subtypes, but only enhanced the affinity of IP3R-2. Thrombin and thrombin receptor activation improved cardiac function after AMI by an IP3R-mediated pathway, probably through the IP3R-2 subtype.

Interleukin 6 augments mechanical strain-induced C-reactive protein synthesis via the stretch-activated channel-nuclear factor κ B signal pathway.

OBJECTIVES: C-reactive protein (CRP), an inflammation marker, is a strong independent risk factor for cardiovascular disease. Vessels are able to express CRP; however, the molecular mechanism behind this expression is not clear. METHODS: Reverse transcription PCR and ELISA were used to detect messenger RNA and proteins of CRP and nuclear factor κB (NF-κB) activity in vessel rings stretched with different mechanical strains. RESULTS: Interleukin (IL)-6 treatment did not induce CRP expression in vessel rings of white rabbits in the absence of mechanical strain. In contrast, IL-6 augmented CRP expression in vessel rings stretched with mechanical strains of 3 and 5 g (CRP mRNA, IL-6: 11.367±1.68 and 12.78±0.76 vs vehicle: 7.27±0.88 and 8.3±0.91 folds, respectively; CRP, IL-6: 12.79±1.62 and 14.05±2.1 vs vehicle: 7.72±1.04 and 8.16±1.52 folds, respectively; p<0.05 vs 0 g group and vehicle control group; n=5), and this effect was completely blocked by treatment with gadolinium III chloride hexahydrate (GdCl3). Moreover, IL-6 treatment increased NF-κB activity in vessels stretched with a mechanical strain of 3 g, and this effect was blocked by stretch-activated channel inhibitors (streptomycin or GdCl3) and the NF-κB peptide inhibitor SN50, but not by the inactive SN50 analogue SN50M. We also performed similar experiments on human internal mammary arteries and obtained similar results. CONCLUSIONS: These results indicate that the inflammatory cytokine IL-6 alone does not induce CRP synthesis in vessels in the absence of mechanical strain; however, IL-6 augments mechanical strain-induced CRP synthesis in vessels via the stretch-activated channel-NF-κB pathway.

Impairment of cardiac function and remodeling induced by myocardial infarction in rats are attenuated by the nonpeptide angiotensin-(1-7) analog AVE 0991.

AIMS: We evaluated effects of the nonpeptide angiotensin (ANG)-(1-7) analog AVE 0991 (AVE) on cardiac function and remodeling as well as transforming growth factor-beta1 (TGF-ß1)/tumor necrosis factor-alpha (TNF-α) expression in myocardial infarction rat models. METHODS AND RESULTS: Sprague-Dawley rats underwent either sham surgery or coronary ligation. They were divided into four groups: sham, control, AVE, and AVE+A-779 [[D-Ala(7) ]-ANG-(1-7), a selective antagonist for the ANG-(1-7)] group. After 4 weeks of treatment, the AVE group displayed a significant elevation in left ventricular fractional shorting (LVFS) (25.5 ± 7.3% vs. 18.4 ± 3.3%, P < 0.05) and left ventricular ejection fraction (LVEF) (44.8 ± 7.6% vs. 32.7 ± 6.5%, P < 0.05) when compared to the control group, but no effects on the left ventricular end-diastolic and end-systolic diameters (LVDd and LVDs, respectively) were observed. In addition, we found that the myocyte diameter (18 ± 2 µm vs. 22 ± 4 µm, P < 0.05), infarct size (42.6 ± 3.6% vs. 50.9 ± 4.4%, P < 0.001) and collagen volume fraction (CVF) (16.4 ± 2.2% vs. 25.3 ± 3.2%, P < 0.001) were significantly reduced in the AVE group when compared to the control group. There were no differences in LVFS, LVEF, myocyte diameter, and infarct size between the control and AVE+A-779 groups. AVE also markedly attenuated the increased mRNA expression of collagen I (P < 0.001) and collagen III (P < 0.001) and inhibited the overexpression of TGF-ß1 (P < 0.05) and TNF-α (P < 0.05) compared to the control group. CONCLUSION: AVE could improve cardiac function and attenuate ventricular remodeling in MI rat models. It may involve the inhibition of inflammatory factors TGF-ß1/TNF-α overexpression and the action on the specific receptor Mas of ANG-(1-7).

Thrombin and its receptor enhance ST-segment elevation in acute myocardial infarction by activating the KATP channel.

ST-segment elevation is the major clinical criterion for committing patients with chest pain to have emergent coronary revascularizations; however, the mechanism responsible for ST-segment elevation is unknown. In a guinea pig model of ST-segment elevation acute myocardial infarction (AMI), local application of hirudin, a thrombin antagonist, significantly decreased AMI-induced ST-segment elevation in a dose-dependent manner. Hirudin-induced (5 antithrombin units [ATU]) decrease in ST elevation was reversed by 250 nmol/L thrombin receptor activator peptide (TRAP). TRAP (250 nmol/L [100 microL]) significantly induced ST-segment elevation in hearts without AMI. The TRAP effect was blocked by 4 mg/kg glibenclamide and 4 mg/kg HMR1098 and partially blocked by 3 mg/kg 5HD. Pinacidil (0.45 mg/kg) simulated the effect of TRAP (250 nmol/L [100 microL]) on hearts without AMI. Moreover, single-channel recordings showed that TRAP induced ATP-sensitive K+ channel (KATP channel) activity, and this effect was blocked by HMR1098 but not 5HD. Finally, TRAP significantly shortened the monophasic action potential (MAP) at 90% repolarization (MAP90) and epicardial MAP (EpiMAP) duration. These effects of TRAP were completely reversed by HMR1098 and partially reversed by 5HD. Thrombin and its receptor activation enhanced ST-segment elevation in an AMI model by activating the sarcolemmal KATP channel.

[Distribution characteristics of traditional Chinese medicine syndromes and their elements in people with subhealth fatigue].

OBJECTIVE: To investigate the characteristics of traditional Chinese medicine (TCM) syndromes and their elements in people with subhealth fatigue. METHODS: The TCM symptoms in line with the diagnostic criteria of subhealth fatigue status were collected by clinical investigations and using information collection form based on TCM four diagnostic methods. Referred to Clinical Guidelines of Chinese Medicine on Subhealth and other related standards, the syndrome type was identified in accordance with clinical symptoms of each patient with subhealth fatigue by two physicians. The data of syndrome differentiation were analyzed by descriptive statistical analysis. RESULTS: There were 81 syndrome types from 495 cases of subhealth fatigue. There were 24 syndrome types after separation, and the top ten were liver stagnation and spleen deficiency, stagnation of liver qi, hyperactivity of liver fire, disharmony between liver and stomach, damp obstruction due to spleen deficiency, deficiency of both heart and spleen, yin deficiency of liver and kidney, yang deficiency of spleen and kidney, stagnation of gallbladder and disturbance of phlegm, and internal disturbance of phlegm-heat. There were 17 syndrome elements, including seven disease location elements and ten disease nature elements. The disease location elements were liver, spleen, kidney, stomach, heart, gallbladder and lung. The disease nature elements were qi stagnation, qi deficiency, exuberance of fire (heat), damp obstruction, phlegm obstruction, yin deficiency, adverse flow of qi, yang deficiency, blood deficiency, and blood stasis. CONCLUSION: Syndrome types of subhealth fatigue involve in deficiency syndrome, excess syndrome, and mixture of deficiency and excess syndromes. The syndrome elements of disease location involve five zang organs and two fu organs, and the liver and spleen were the most frequently involved organs. The syndrome elements of disease nature involve deficiency and excess. Qi stagnation is most frequently involved in the excess syndrome, and qi deficiency is most frequently involved in the deficiency syndrome.

Change in high-sensitive C-reactive protein during abdominal aortic aneurysm formation.

OBJECTIVES: We try to clear the relationship between high-sensitive C-reactive protein (hsCRP) release and abdominal aortic aneurysm formation. METHODS AND RESULTS: A rabbit abdominal aortic aneurysm model was created by elastase perfusion. At days 10, 20, and 30 after elastase perfusion, mean serum hsCRP levels detected by ELISA increased over 200% over their basal level (n = 11, P < 0.05). Serum hsCRP levels were significantly higher in the aneurysm groups than in the sham controls by day 5 (n = 11, P < 0.05) and were positively correlated with percentage vessel diameter changes in the aneurysm group by day 10 (r = 0.8012, n = 33, P < 0.05). In the aneurysm group, increased serum CRP was derived from the liver in early stages, yet from dilated vessels in the later stages, as shown by immunostaining, western blot, and reverse transcriptase-PCR. Similar increased hsCRP levels were also observed in dissected rabbit aortic ring explants from the aneurysm model. Pretreatment with the stretch-activated channel blockers gadolinium or streptomycin, as well as nuclear factor-kappaB inhibitor SN50, blocked hsCRP production in the dilated aortic rings. Stretch-activated channel blockers also inhibited the activation of nuclear factor-kappaB. CONCLUSION: During abdominal aortic aneurysm formation, increased serum hsCRP levels derive from aneurysmal arteries with degenerating elastic lamina. This process is mediated by mechanical stretch-activated channel-dependent nuclear factor-kappaB translocation to the nucleus.

Mechanical strain induces expression of C-reactive protein in human blood vessels.

C-reactive protein (CRP) is a powerful independent risk factor for cardiovascular diseases. Elevated mechanical strain on vessels induces the local expression of proinflammatory cytokines. We hypothesized that mechanical strain on vessels may induce local CRP expression. Human saphenous vein and internal mammary artery (IMA) rings were stretched in vitro with a mechanical strength of 1, 3, or 5 g. Reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay results showed that mechanical stretching significantly induced CRP mRNA and protein expression in the saphenous vein and IMA rings in a strength-dependent manner reaching a maximum at a mechanical strength of 3 g, but CRP expression returned at strengths of >5 g. In vessels, mechanical strain-induced CRP expression was blocked by two stretch-activated ion channel (SAC) blockers: GdCl(3) and streptomycin. Mechanical strain also increased activation of nuclear factor kappaB (NF-kappaB), which was detected with a nonradioactive NF-kappaB p50/p65 EZ-TFA transcription factor assay. Mechanical strain-induced NF-kappaB activation was blocked by SAC blockers and the NF-kappaB inhibitor (SN50, H-Ala-Ala-Val-Ala-Leu-Leu-Pro-Ala-Val-Leu-Leu-Ala-Leu-Leu-Ala-Pro-Val-Gln-Arg-Lys-Arg-Gln-Lys-Leu-Met-Pro-OH). SN50 also blocked mechanical strain-induced CRP expression in vessels. In conclusion, mechanical strain induces CRP expression in IMAs and saphenous veins by activating the SAC-induced NF-kappaB pathway.

Effect of long-term B-type natriuretic peptide treatment on left ventricular remodeling and function after myocardial infarction in rats.

Although short-term B-type natriuretic peptide (BNP) treatment has been shown to be effective for decompensated congestive heart failure, little is known about the effects of long-term BNP treatment in ventricular remodeling and heart failure in response to myocardial infarction. The aim of the present study was to investigate the effects of long-term BNP treatment on ventricular remodeling and heart failure after myocardial infarction in rats. Myocardial infarction was induced by ligating the left anterior descending coronary artery. The surviving rats were randomly divided into four groups: 1) vehicle-treated myocardial infarction group ('vehicle-treated group'), 2) rats treated with low-dose BNP ('low BNP group'), 3) rats treated with high-dose BNP ('high BNP group'), 4) sham-operated group. Eight weeks after the operation, rats were sacrificed. Compared with the sham-operated group, the vehicle-treated group had significantly higher collagen deposition and angiotensin II levels (P<0.01) and a significantly lower cardiac function (P<0.05). Both BNP-treated groups had significant improvement of these indexes compared with the vehicle-treated group (P<0.01). The high BNP group had significantly less collagen deposition and better cardiac function than the untreated and low BNP groups. Moreover, the mRNA and protein expression of TGFbeta1 and Smad2 in the vehicle-treated group was significantly higher than in the sham-operated group (P<0.01). Both BNP-treated groups had a suppression of TGFbeta1 and Smad2 expression (P<0.01). In conclusion, long-term treatment with BNP prevents ventricular remodeling and deterioration of cardiac function in a dose-dependent fashion, a process that may be associated with the inhibition of TGFbeta1/ Smad2 signaling.

Thrombin receptor and ventricular arrhythmias after acute myocardial infarction.

The mechanism mediating the development of ventricular arrhythmia (VA) after acute myocardial infarction (AMI) is still uncertain. Thrombin receptor (TR) activation has been proven to be arrhythmogenic in many other situations, and we hypothesize that it may participate in the genesis of post-AMI VA. Using a left coronary artery ligation rat model of AMI, we found that a local injection of hirudin into the left ventricle (LV) significantly reduced the ratio of VA durations to infarction sizing, whereas injection of thrombin receptor-activating peptide (TRAP) increased the ratios of VA duration to infarction sizing. The effects of TR activation on whole-cell currents were investigated in isolated myocytes. TRAP increased a glibenclamide-sensitive outward current. Pretreatment of rats with glibenclamide (4 mg/kg intraperitoneally) eliminated the effects of a local injection of TRAP on the ratios of VA durations to infarction sizing. TR mRNA and protein expression in the ischemic left ventricle had reached its peak by 20 min postligation in the rat AMI model (P < 0.05). TR-immunoreactive myocytes were observed in infarcted LV but were seldom seen in the right ventricle or in the normal heart. By 60 min, TR transcript levels had returned to control levels. We conclude that increased TR activation and expression in the infarcted LV after AMI may contribute to VA through a mechanism involving glibenclamide-sensitive potassium channels.

Granulation encapsulated stent: a new therapeutic approach for vascular implantation.

OBJECTIVES: To determine if stents could be encapsulated with immunocompatible granulation tissue for the treatment of vascular diseases. METHODS: Bare metal stents were implanted in New Zealand white rabbits so they would be encapsulated with immunocompatible granulation tissue. The granulation encapsulated stents (GES) were then treated with either mitomycin C or saline, and implanted into rabbit iliac arteries for 4 weeks. To test whether the effect of mitomycin C was retained, we co-cultured smooth muscle cells for 3 h with subcutaneous tissue (as control) or with granulation tissue from GES treated with mitomycin C and saline. RESULTS: Vessels with GES treated with mitomycin C (MS) and washed with saline had significantly less neointimal area (NA) after 4 weeks (0.27 (SD 0.03) mm(2) than vessels containing bare metal stents (B) (1.15 (SD 0.10) mm(2), n = 5, p<0.05) or GES treated with saline (S) (4.78 (SD 0.72) mm(2), n = 5, p<0.05). The average vessel injury score was not significantly different among these three groups (S: 1.98 (SD 0.51), MS: 1.46 (SD 0.18) and B: 1.51 (SD 0.32)). GES treated with saline had significantly less NA than the other two groups and also blocked blood flow in the contralateral iliac artery in the abdominal aortic bifurcation immediately after implantation and 4 weeks later. Histology also showed neointimal overgrowth in the vessel wall over the contralateral iliac artery. CONCLUSIONS: GES treated with mitomycin C can significantly inhibit neointimal formation in rabbit arteries due to the formation of granulation tissue. GES treated with saline demonstrated significantly increased NA and resisted normal rabbit artery pressures.

Platelet-derived growth factor-AB promotes the generation of adult bone marrow-derived cardiac myocytes.

The directed generation of cardiac myocytes from endogenous stem cells offers the potential for novel therapies for cardiovascular disease. To facilitate the development of such approaches, we sought to identify and exploit the pathways directing the generation of cardiac myocytes from adult rodent bone marrow cells (BMCs). In vitro cultures supporting the spontaneous generation of functional cardiac myocytes from murine BMCs demonstrated induced expression of platelet-derived growth factor (PDGF)-A and -B isoforms with alpha- and beta-myosin heavy chains as well as connexin43. Supplementation of PDGF-AB speeded the kinetics of myocyte development in culture by 2-fold. In a rat heart, myocardial infarction pretreatment model PDGF-AB also promoted the derivation of cardiac myocytes from BMCs, resulting in a significantly greater number of islands of cardiac myocyte bundles within the myocardial infarction scar compared with other treatment groups. However, gap junctions were detected only between the cardiac myocytes receiving BMCs alone, but not BMCs injected with PDGF-AB. Echocardiography and exercise testing revealed that the functional improvement of hearts treated with the combination of BMCs and PDGF-AB was no greater than with injections of BMCs or PDGF-AB alone. These studies demonstrated that PDGF-AB enhances the generation of BMC-derived cardiac myocytes in rodent hearts, but suggest that alterations in cellular patterning may limit the functional benefit from the combined injection of PDGF-AB and BMCs. Strategies based on the synergistic interactions of PDGF-AB and endogenous stem cells will need to maintain cellular patterning in order to promote the restoration of cardiac function after acute coronary occlusion.

Genetically engineered biologically based hemostatic bioassay.

Real-time direct measures of hemostatic parameters in vivo are required for optimizing the dynamic delivery of coagulation modifying pharmacotherapies. Typical sensors of physiologic functions in vivo, however, have only a restricted array of sensory inputs, and thus limited capacity to monitor thrombotic and hemostatic activity. To overcome this limitation we have developed a genetically engineered excitable cell line that can be potentially used for an implantable thrombin biosensor. Specifically, we have generated stem cell-derived cardiac myocyte aggregates overexpressing the human thrombin receptor, protease activated receptor-1 (PAR-1), which exploit the inherent electropotential input-output relationship of the cells to detect local changes in thrombin activity. In vitro, the signaling activity of PAR-1 cardiac myocytes was highly responsive to thrombin, inducing a sixfold increase in intracellular cAMP as compared with a twofold increase in control cells. In vivo, the engineered myocytes also detected alterations in local coagulation potential. Specifically, PAR-1 engineered cells implanted in vivo detected local increases in thrombin with a doubling in chronotropic activity compared with a 50% increase in control aggregates. Overall these studies demonstrate the potential of genetic engineering to expand the physiologic signals recognized by excitable cells, and may facilitate the translation of this approach for the real-time monitoring of hemostatic function in vivo.