Topical Skin Application of Small-Molecule Antiplatelet Agent against Pressure Injury in Rat Models.

Due to prolonged forced positioning, the incidence of intraoperative pressure injuries is high. This study aimed to explore the impact of small-molecule antiplatelet drugs on pressure injuries by locally applying them before an injury occurs. In the first part of this study, water-soluble tracers with different molecular weights were applied to normal and early-stage pressure-injured skin. Through digital cameras, spectrophotometers, and histological observations, the penetration of tracers into the epidermis was clarified. In the second part of this study, a water-soluble antiplatelet drug called Trapidil (molecular weight = 205 Da) was applied to the left side of the back of a rat before, during, and after compression, and the contralateral side served as a non-intervention control group. The differences in pressure injuries between the two groups were observed through a digital camera, an ultraviolet camera, and temperature measurement, and skin circulation and perfusion were assessed via an intravenous injection of Evans Blue. The first part of this study found that water-soluble tracers did not easily penetrate normal skin but could more easily penetrate pressure-damaged skin. The smaller the molecular weight of the tracer, the easier it penetrated the skin. Therefore, in the next step of research, water-soluble drugs with smaller molecular weights should be selected. The second part of this study found that, compared with the control group, the occurrence rates and areas of ulcers were lower, the gray value was higher, and the skin temperature was lower in the Trapidil group (p < 0.05). After the intravenous Evans Blue injection, skin circulation and perfusion in the Trapidil group were found to be better. In conclusion, this study found that the topical skin application of a small-molecule antiplatelet agent may have significant effects against pressure injuries by improving post-decompression ischemia, providing new insights into the prevention and treatment of intraoperative pressure injuries.

Fluctuations in Detection Indicators and Their Significance for the Diagnosis of Early Pressure Injury in Rat Models.

PURPOSE: The aim of this study was to identify the most meaningful diagnostic indicator for distinguishing blanchable erythema (BE) and stage 1 pressure injury (early PI) in an in vivo (rat) model. DESIGN: A prospective case-control design was used to complete a horizontal and vertical comparison of detection indicators during the process of fading of BE or the deterioration of early PI into ulcer in rat models. MATERIALS AND SETTING: The sample comprised 5 hairless rats with 20 injuries, of which 10 were BE and the other 10 were early PI. Data were collected at Nagano College of Nursing in 2020 in Nagano, Japan. METHODS: The BE and PI rat models were established by subjecting the dorsal skin of a hairless rat to compression between 2 neodymium magnets for 45 minutes and 3.45 hours, respectively. The affected skin was observed based on the following: (1) photography, (2) hardness, (3) temperature, (4) moisture, and (5) spectrophotometric (a* value and ultraviolet [UV] reflectance) measurements. All measurements of BE were performed at the beginning to 60 minutes after decompression, and those for early PI were performed until 48 hours after decompression. RESULTS: Multiple BE factors, such as the degree of erythema (macroscopy and a* value), hardness, temperature, and moisture, were found to have unstable fluctuations. Only UV reflectance gradually decreased from 6 hours and decreased significantly at 48 hours after decompression (P = .001 vs 1 hour). In contrast to early PI, erythema in BE obviously faded within 10 minutes. CONCLUSIONS: Study findings indicate that a continuous decrease in UV reflectance can reflect the worsening of hemorrhage in early (stage 1) PI. In contrast, other indicators including photography, skin hardness, temperature, and moisture fluctuated and did not prove predictive for PI progression. The obvious fading of erythema in BE a short time after decompression can be used for clinical observations.

A comprehensive analysis of multi-circulatory disorders in early pressure injury and their diagnostic significance in rat models.

Early pressure injury (PI) progression is associated with multi-circulatory disorders and they interplay with each other, resulting in a lack of a satisfactory diagnostic method. We generated early PI and blanchable erythema hairless rat models. Transparent disc method and capillary refilling time test (CRTT) results were recorded with ultraviolet camera to capture the dynamics changes, and the blanching index and refilling index were set for comprehensive analysis. The deteriorated areas of early PI showed non-blanchable erythema (NBE) and an increase in erythema at 0.5 and 6 h with the transparent disc method. CRTT showed a marked refilling delay at 12 h. The comprehensive analysis of blanching index and refilling index showed a significant change in erythema from NBE at 0.5 h and ischemia progressing to hemorrhage at 18 h. There was also a marked difference in the deteriorating and improving areas within the same erythema. Pathological analysis showed inflammatory cell infiltration, with marked edema accompanied by increased hemorrhage and tissue necrosis. Furthermore, small arteries and veins with thrombosis and microthrombi were observed. Consistent ischemia after decompression and subsequent hemorrhage are important indicators, and comprehensive analysis can help increase the positive diagnosis rate over that for other circulatory disorders alone.

Thermal preconditioning can reduce the incidence of intraoperatively acquired pressure injuries.

Intraoperatively acquired pressure injuries (IAPIs) occur frequently among patients who undergo surgical procedures that last longer than 3 h. Several studies indicated that heat shock proteins (HSPs) play an important role in the protection of stress-induced damages in skin tissues. Hence, the aim of this study was to investigate the potential preventive effect of thermal preconditioning (TPC) on IAPIs in surgical patients and rats and to identify the differentially expressed HSP genes in response to the above treatment. TPC was performed on one group of hairless rats before the model of pressure injuries was established. Subsequently, the size of skin lesions was measured and the expression levels of mRNA and protein of HSPs of the pressured skin were detected by real-time polymerase chain reaction (RT-PCR), western blot, and immunohistochemical staining. For human studies, 118 surgical patients were randomly divided into the TPC group (n = 59) and the control group (n = 59), respectively. The temperature and pressure of sacral skin, as well as the incidence of pressure injury (PI) were detected and compared. In animal studies, TPC significantly reduced both the size and incidence of PI in rats on the second, third and fourth days post treatment. In addition, the expression levels of both mRNA and protein of HSP27 were increased in the TPC group, compared with the control group. Immunohistochemical staining showed that HSP27 was distributed in various types of dermal cells and increased in basal cells. In human studies, a significant reduction (75%) of IAPIs was observed among the patients in the TPC group. TPC can reduce the incidence of PI in rats and humans, and the upregulation of HSP27 may play an important role in this biological progress. Further studies are warranted to explore the molecular mechanism of the preventive effect in PI mediated by HSP27.

Elucidation of Ischemic Mechanisms of Early Pressure Injury during Post-Decompression and Detecting Methods.

Background: Pressure injuries (PIs) generally result from prolonged ischemia through localized skin compression, and ischemia persists and exacerbates damage even post-decompression. The mechanisms of ischemia post-decompression are still unclear, and appropriate methods for detection are lacking. Methods: We used blanchable erythema (BE) and early PI rat models. We assessed the perfusion using Evans Blue (EB) and thrombus formation under a light microscope. Furthermore, we performed a capillary refill time test (CRTT) to detect ischemia after depression coupled with the transparent disk method using a spectrophotometer. Results: Compared with the BE group, the early PI group showed significantly slow and insufficient perfusion, as determined by EB staining (p < 0.001). Histological observations revealed that ischemia during post-decompression of early PI was caused by a greater amount of thrombi. The CRTT results showed that although both groups exhibited varying degrees of insufficient refilling volume, the early PI group had significantly slower refilling than the BE group (p < 0.001), which persisted during the deterioration or disappearance of erythema. Conclusions: Our results showed that persistent ischemia caused by thrombi is an important cause of early PI deterioration post-decompression. Therefore, the performance of CRTT coupled with the transparent disc method may become a promising method for detecting ischemia post-decompression.

Predicting the different progressions of early pressure injury by ultraviolet photography in rat models.

Early pressure injury (PI) can result in either spontaneous healing (SH) or deterioration into ulcer (DU). However, determining whether PI will progress into SH or DU on the basis of non-blanchable erythema only is difficult. In this study, we constructed two animal PI models to mimic SH and DU injuries and observed haemorrhage by using ultraviolet (UV) photography to develop potential clinical indicators for predicting the progression of early PI. Macroscopy, UV photography, and skin temperature observations were obtained. In the SH group, macroscopic observation showed the erythema was obvious at 0.5 hours after decompression and faded gradually had almost disappeared at 72 hours. In the DU group, the erythema persisted, and an erosion appeared at 24 hours after decompression and expanded at 36 hours. The erythema developed into an obvious ulcer at 48 hours and enlarged at 72 hours. The obvious ulcer found at 48 hours through macroscopic observation was clearly visible at 36 hours with UV photography, and a significant difference in grey values between the two groups was found at as early as 18 hours (P < .05). This study provided evidence showing that UV photography can predict the different progression stages of early PI. Additionally, when combined with the transparent disc method, UV photography also can be used to identify the circulatory disorders of early PI, such as haemorrhage or hyperaemia and even congestion.

Combination therapy with pemafibrate (K-877) and pitavastatin improves vascular endothelial dysfunction in dahl/salt-sensitive rats fed a high-salt and high-fat diet.

BACKGROUND: Statins suppress the progression of atherosclerosis by reducing low-density lipoprotein (LDL) cholesterol levels. Pemafibrate (K-877), a novel selective peroxisome proliferator-activated receptor α modulator, is expected to reduce residual risk factors including high triglycerides (TGs) and low high-density lipoprotein (HDL) cholesterol during statin treatment. However, it is not known if statin therapy with add-on pemafibrate improves the progression of atherosclerosis. The aim of this study was to assess the effect of combination therapy with pitavastatin and pemafibrate on lipid profiles and endothelial dysfunction in hypertension and insulin resistance model rats. METHODS: Seven-week-old male Dahl salt-sensitive (DS) rats were divided into the following five treatment groups (normal diet (ND) plus vehicle, high-salt and high-fat diet (HD) plus vehicle, HD plus pitavastatin (0.3 mg/kg/day), HD plus pemafibrate (K-877) (0.5 mg/kg/day), and HD plus combination of pitavastatin and pemafibrate) and treated for 12 weeks. At 19 weeks, endothelium-dependent relaxation of the thoracic aorta in response to acetylcholine was evaluated. RESULTS: After feeding for 12 weeks, systolic blood pressure and plasma levels of total cholesterol were significantly higher in the HD-vehicle group compared with the ND-vehicle group. Combination therapy with pitavastatin and pemafibrate significantly reduced systolic blood pressure, TG levels, including total, chylomicron (CM), very LDL (VLDL), HDL-TG, and cholesterol levels, including total, CM, VLDL, and LDL-cholesterol, compared with vehicle treatment. Acetylcholine caused concentration-dependent relaxation of thoracic aorta rings that were pre-contracted with phenylephrine in all rats. Relaxation rates in the HD-vehicle group were significantly lower compared with the ND-vehicle group. Relaxation rates in the HD-combination of pitavastatin and pemafibrate group significantly increased compared with the HD-vehicle group, although neither medication alone ameliorated relaxation rates significantly. Western blotting experiments showed increased phosphorylated endothelial nitric oxide synthase protein expression in aortas from rats in the HD-pemafibrate group and the HD-combination group compared with the HD-vehicle group. However, the expression levels did not respond significantly to pitavastatin alone. CONCLUSIONS: Combination therapy with pitavastatin and pemafibrate improved lipid profiles and endothelial dysfunction in hypertension and insulin resistance model rats. Pemafibrate as an add-on strategy to statins may be useful for preventing atherosclerosis progression.

Inhibitory Effects of Tofogliflozin on Cardiac Hypertrophy in Dahl Salt-Sensitive and Salt-Resistant Rats Fed a High-Fat Diet.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are drugs for diabetes and might prevent heart failure. In this study, we investigated the effects of tofogliflozin, an SGLT2 inhibitor, on cardiac hypertrophy and metabolism in hypertensive rats fed a high-fat diet. Dahl salt-sensitive (DS) rats, hypertensive model rats, and Dahl salt-resistant (DR) rats, non-hypertensive model rats, were fed a high-salt and high-fat diet containing tofogliflozin (0.005%) for 9 weeks to examine the effects of this drug on cardiac hypertrophy and metabolism. Tofogliflozin tended to suppress a rise of the systolic blood pressure, relative to the control, throughout the treatment period in both DR and DS rats, and significantly suppress a rise of the systolic blood pressure, relative to the control, at the 9th week in DS rats. Tofogliflozin reduced cardiac hypertrophy (heart weight/body weight) not only in DS rats but also in DR rats. Histological analysis showed that tofogliflozin significantly decreased cardiomyocyte hypertrophy and perivascular fibrosis in both DS and DR rats. Tofogliflozin significantly decreased the expression levels of genes related to cardiac hypertrophy (encoding for natriuretic peptides A and B and interleukin-6), and to cardiac fibrosis (encoding for transforming growth factor-ß1 and collagen type IV), in DS rats. Recent studies have shown that hypertrophied and failing hearts shift to oxidizing ketone bodies as a significant fuel source. We also performed metabolome analysis for ventricular myocardial tissue. Tofogliflozin reduced 3-hydroxybutyrate, a ketone body, and significantly decreased the expression levels of ß-hydroxybutyrate dehydrogenase 1 and 3-oxoacid CoA-transferase, which are related to ketone oxidization. In conclusion, tofogliflozin ameliorated cardiac hypertrophy and fibrosis along with reduction of ketone usage in myocardial tissue.

Effect of LCZ696, a dual angiotensin receptor neprilysin inhibitor, on isoproterenol-induced cardiac hypertrophy, fibrosis, and hemodynamic change in rats.

BACKGROUND: Recent clinical studies have shown that treatment with LCZ696, a complex containing the angiotensin receptor blocker valsartan and neprilysin inhibitor sacubitril, improves the prognosis of heart failure patients with a reduced ejection fraction. This study evaluated whether LCZ696 affects left ventricular hypertrophy, fibrosis, and hemodynamics in isoproterenol (ISO)-treated rats compared with valsartan alone. METHODS: Male Wistar rats received subcutaneous saline (n = 10), subcutaneous ISO (2.4 mg/kg/day; n = 10), subcutaneous ISO + oral LCZ696 (60 mg/kg/day; n = 20) (ISO-LCZ), or subcutaneous ISO + oral valsartan (30 mg/kg/day; n = 20) (ISO-VAL) for 7 days. RESULTS: LCZ696 and valsartan did not significantly reduce the increased heart weight/body weight ratio in rats treated with ISO. Echocardiography showed that the deceleration time shortened by ISO was restored by LCZ696 but not valsartan alone (p = 0.01 vs. the ISO group). Histological analysis showed that cardiac interstitial fibrosis increased by ISO was decreased significantly by LCZ696 but not valsartan alone (control: 0.10 ± 0.14%; ISO: 0.41 ± 0.32%; ISO-LCZ: 0.19 ± 0.23% [p < 0.01 vs. the ISO group]; ISO-VAL: 0.34 ± 0.23% [p = 0.34 vs. the ISO group]). Quantitative polymerase chain reaction showed that mRNA expression of Tgfb1, Col1a1, Ccl2, and Anp increased by ISO was significantly attenuated by LCZ696 but not valsartan alone (p < 0.05 vs. the ISO group). CONCLUSIONS: LCZ696 improves cardiac fibrosis, but not hypertrophy, caused by continuous exposure to ISO in rats.

Suppression of Wnt Signaling and Osteogenic Changes in Vascular Smooth Muscle Cells by Eicosapentaenoic Acid.

Vascular medial calcification is often observed in patients with arteriosclerosis. It is also associated with systolic hypertension, wide pulse pressure, and fluctuation of blood pressure, which results in cardiovascular events. Eicosapentaenoic acid (EPA) has been shown to suppress vascular calcification in previous animal experiments. We investigated the inhibitory effects of EPA on Wnt signaling, which is one of the important signaling pathways involved in vascular calcification. Intake of food containing 5% EPA resulted in upregulation of the mRNA expression of Klotho, an intrinsic inhibitor of Wnt signaling, in the kidneys of wild-type mice. Expression levels of ß-catenin, an intracellular signal transducer in the Wnt signaling pathway, were increased in the aortas of Klotho mutant (kl/kl) mice compared to the levels in the aortas of wild-type mice. Wnt3a or BIO, a GSK-3 inhibitor that activates ß-catenin signaling, upregulated mRNA levels of AXIN2 and LEF1, Wnt signaling marker genes, and RUNX2 and BMP4, early osteogenic genes, in human aorta smooth muscle cells. EPA suppressed the upregulation of AXIN2 and BMP4. The effect of EPA was cancelled by T0070907, a PPARγ inhibitor. The results suggested that EPA could suppress vascular calcification via the inhibition of Wnt signaling in osteogenic vascular smooth muscle cells via PPARγ activation.

Eicosapentaenoic acid prevents arterial calcification in klotho mutant mice.

BACKGROUND: The klotho gene was identified as an "aging-suppressor" gene that accelerates arterial calcification when disrupted. Serum and vascular klotho levels are reduced in patients with chronic kidney disease, and the reduced levels are associated with arterial calcification. Intake of eicosapentaenoic acid (EPA), an n-3 fatty acid, reduces the risk of fatal coronary artery disease. However, the effects of EPA on arterial calcification have not been fully elucidated. The aim of this study was to determine the effect of EPA on arterial calcification in klotho mutant mice. METHODS AND RESULTS: Four-week-old klotho mutant mice and wild-type (WT) mice were given a diet containing 5% EPA (EPA food, klotho and WT: n = 12, each) or not containing EPA (control food, klotho and WT: n = 12, each) for 4 weeks. Calcium volume scores of thoracic and abdominal aortas assessed by computed tomography were significantly elevated in klotho mice after 4 weeks of control food, but they were not elevated in klotho mice after EPA food or in WT mice. Serum levels of EPA and resolvin E1, an active metabolite of EPA, in EPA food-fed mice were significantly increased compared to those in control food-fed mice. An oxidative stress PCR array followed by quantitative PCR revealed that NADPH oxidase-4 (NOX4), an enzyme that generates superoxide, gene expression was up-regulated in arterial smooth muscle cells (SMCs) of klotho mice. Activity of NOX was also significantly higher in SMCs of klotho mice than in those of WT mice. EPA decreased expression levels of the NOX4 gene and NOX activity. GPR120, a receptor of n-3 fatty acids, gene knockdown by siRNA canceled effects of EPA on NOX4 gene expression and NOX activity in arterial SMCs of klotho mice. CONCLUSIONS: EPA prevents arterial calcification together with reduction of NOX gene expression and activity via GPR120 in klotho mutant mice.

Intratracheal Administration of Prostacyclin Analogue-incorporated Nanoparticles Ameliorates the Development of Monocrotaline and Sugen-Hypoxia-induced Pulmonary Arterial Hypertension.

Nanoparticles (NPs) have been used as novel drug delivery systems. Drug-incorporated NPs for local delivery might optimize the efficacy and minimize the side effects of drugs. Intravenous prostacyclin improves long-term survival in patients with pulmonary arterial hypertension (PAH), but it causes serious side effects such as catheter-related infections. We investigated the efficacy and safety of intratracheal administration of a prostacyclin analogue, beraprost (BPS), incorporated NPs in Sugen-hypoxia-normoxia and monocrotaline rat models of PAH and in human PAH pulmonary arterial smooth muscle cells (PASMCs). After a single administration, BPS NPs significantly decreased right ventricular pressure, right ventricular hypertrophy, and pulmonary artery muscularization in the 2 rat models. BPS NPs significantly improved the survival rate in the monocrotaline rat model. No infiltration of inflammatory cells, hemorrhage, or fibrosis was found in the liver, kidney, spleen, and heart after the administration of BPS NPs. No liver or kidney dysfunction was found in the blood examinations. BPS and BPS NPs significantly inhibited the proliferation of human PAH PASMCs after 24 hours of treatment. BPS NPs significantly continued to inhibit the proliferation of human PAH PASMCs at 24 hours after the removal of BPS NPs. BPS NPs significantly induced apoptosis in PAH PASMCs compared to that in non-PAH PASMCs. Intratracheal administration of BPS NPs ameliorates pulmonary hypertension in PAH rat models by a sustained antiproliferative effect and a proapoptotic effect on PAH PASMCs.

Delivery of imatinib-incorporated nanoparticles into lungs suppresses the development of monocrotaline-induced pulmonary arterial hypertension.

Platelet-derived growth factor (PDGF) is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). Imatinib, a PDGF-receptor tyrosine kinase inhibitor, improved hemodynamics, but serious side effects and drug discontinuation are common when treating PAH. A drug delivery system using nanoparticles (NPs) enables the reduction of side effects while maintaining the effects of the drug. We examined the efficacy of imatinib-incorporated NPs (Ima-NPs) in a rat model and in human PAH-pulmonary arterial smooth muscle cells (PASMCs). Rats received a single intratracheal administration of PBS, FITC-NPs, or Ima-NPs immediately after monocrotaline injection. Three weeks after monocrotaline injection, intratracheal administration of Ima-NPs suppressed the development of pulmonary hypertension, small pulmonary artery remodeling, and right ventricular hypertrophy in the rat model of monocrotaline-induced PAH. We also examined the effects of imatinib and Ima-NPs on PDGF-induced proliferation of human PAH-PASMCs by (3)H-thymidine incorporation. Imatinib and Ima-NPs significantly inhibited proliferation after 24 hours of treatment. Ima-NPs significantly inhibited proliferation compared with imatinib at 24 hours after removal of these drugs. Delivery of Ima-NPs into lungs suppressed the development of MCT-induced PAH by sustained antiproliferative effects on PAS-MCs.

Electrocardiographic parameters and fatal arrhythmic events in patients with Brugada syndrome: combination of depolarization and repolarization abnormalities.

OBJECTIVES: This study aimed to determine the usefulness of the combination of several electrocardiographic markers on risk assessment of ventricular fibrillation (VF) in patients with Brugada syndrome (BrS). BACKGROUND: Detection of high-/low-risk BrS patients using a noninvasive method is an important issue in the clinical setting. Several electrocardiographic markers related to depolarization and repolarization abnormalities have been reported, but the relationship and usefulness of these parameters in VF events are unclear. METHODS: Baseline characteristics of 246 consecutive patients (236 men; mean age, 47.6 ± 13.6 years) with a Brugada-type electrocardiogram, including 13 patients with a history of VF and 40 patients with a history of syncope episodes, were retrospectively analyzed. During the mean follow-up period of 45.1 months, VF in 23 patients and sudden cardiac death (SCD) in 1 patient were observed. Clinical/genetic and electrocardiographic parameters were compared with VF/SCD events. RESULTS: On univariate analysis, a history of VF and syncope episodes, paroxysmal atrial fibrillation, spontaneous type 1 pattern in the precordial leads, and electrocardiographic markers of depolarization abnormalities (QRS duration ≥120 ms, and fragmented QRS [f-QRS]) and those of repolarization abnormalities (inferolateral early repolarization [ER] pattern and QT prolongation) were associated with later cardiac events. On multivariable analysis, a history of VF and syncope episodes, inferolateral ER pattern, and f-QRS were independent predictors of documented VF and SCD (odds ratios: 19.61, 28.57, 2.87, and 5.21, respectively; p < 0.05). Kaplan-Meier curves showed that the presence/absence of inferolateral ER and f-QRS predicted a worse/better prognosis (log-rank test, p < 0.01). CONCLUSIONS: The combination of depolarization and repolarization abnormalities in BrS is associated with later VF events. The combination of these abnormalities is useful for detecting high- and low-risk BrS patients.

Effect of vildagliptin, a dipeptidyl peptidase 4 inhibitor, on cardiac hypertrophy induced by chronic beta-adrenergic stimulation in rats.

BACKGROUND: Heart failure with left ventricular (LV) hypertrophy is often associated with insulin resistance and inflammation. Recent studies have shown that dipeptidyl peptidase 4 (DPP4) inhibitors improve glucose metabolism and inflammatory status. We therefore evaluated whether vildagliptin, a DPP4 inhibitor, prevents LV hypertrophy and improves diastolic function in isoproterenol-treated rats. METHODS: Male Wistar rats received vehicle (n = 20), subcutaneous isoproterenol (2.4 mg/kg/day, n = 20) (ISO), subcutaneous isoproterenol (2.4 mg/kg/day + oral vildagliptin (30 mg/kg/day, n = 20) (ISO-VL), or vehicle + oral vildagliptin (30 mg/kg/day, n = 20) (vehicle-VL) for 7 days. RESULTS: Blood pressure was similar among the four groups, whereas LV hypertrophy was significantly decreased in the ISO-VL group compared with the ISO group (heart weight/body weight, vehicle: 3.2 ± 0.40, ISO: 4.43 ± 0.39, ISO-VL: 4.14 ± 0.29, vehicle-VL: 3.16 ± 0.16, p < 0.05). Cardiac catheterization revealed that vildagliptin lowered the elevated LV end-diastolic pressure observed in the ISO group, but other parameters regarding LV diastolic function such as the decreased minimum dp/dt were not ameliorated in the ISO-VL group. Histological analysis showed that vildagliptin attenuated the increased cardiomyocyte hypertrophy and perivascular fibrosis, but it did not affect angiogenesis in cardiac tissue. In the ISO-VL group, quantitative PCR showed attenuation of increased mRNA expression of tumor necrosis factor-α, interleukin-6, insulin-like growth factor-l, and restoration of decreased mRNA expression of glucose transporter type 4. CONCLUSIONS: Vildagliptin may prevent LV hypertrophy caused by continuous exposure to isoproterenol in rats.

Increased passive stiffness of cardiomyocytes in the transverse direction and residual actin and myosin cross-bridge formation in hypertrophied rat hearts induced by chronic ß-adrenergic stimulation.

BACKGROUND: Left ventricular (LV) hypertrophy is often present in patients with diastolic heart failure. However, stiffness of hypertrophied cardiomyocytes in the transverse direction has not been fully elucidated. The aim of this study was to assess passive cardiomyocyte stiffness of hypertrophied hearts in the transverse direction and the influence of actin-myosin cross-bridge formation on the stiffness. METHODS AND RESULTS: Wistar rats received a vehicle (control) or isoproterenol (ISO) subcutaneously. After 7 days, compared with the controls, ISO administration had significantly increased heart weight and LV wall thickness and had decreased peak early annular relaxation velocity (e') assessed by echocardiography. Elastic modulus of living cardiomyocytes in the transverse direction assessed by an atomic force microscope was significantly higher in the ISO group than in controls. We added butanedione monoxime (BDM), an inhibitor of actin-myosin interaction, and blebbistatin, a specific myosin II inhibitor, to the medium. BDM and blebbistatin significantly reduced the elastic modulus of cardiomyocytes in the ISO group. X-ray diffraction analysis showed that the reflection intensity ratio (I((1,0))/I((1,1))) at diastole was not different before and after treatment with BDM, which induces complete relaxation, in control hearts, but that I((1,0))/I((1,1)) was significantly increased after BDM treatment in the ISO group, indicating residual cross-bridge formation in hypertrophied hearts. CONCLUSIONS: Passive cardiomyocyte stiffness in the transverse direction is increased in hearts with ISO-induced hypertrophy and this is caused by residual actin-myosin cross-bridge formation.

Pro-apoptotic effects of imatinib on PDGF-stimulated pulmonary artery smooth muscle cells from patients with idiopathic pulmonary arterial hypertension.

BACKGROUND: Remodeling of the pulmonary artery by an inappropriate increase of pulmonary artery smooth muscle cells (PASMCs) is problematic in the treatment of idiopathic pulmonary arterial hypertension (IPAH). Effective treatment that achieves reverse remodeling is required. The aim of this study was to assess the pro-apoptotic effects of imatinib, a platelet-derived growth factor (PDGF)-receptor tyrosine kinase inhibitor, on PASMCs obtained from patients with IPAH. METHODS: PASMCs were obtained from 8 patients with IPAH undergoing lung transplantation. Cellular proliferation was assessed by (3)H-thymidine incorporation. Pro-apoptotic effects of imatinib were examined using TUNEL and caspase-3,7 assays and using transmission electron microscopy. RESULTS: Treatment with imatinib (0.1 to 10 µg/mL) significantly inhibited PDGF-BB (10 ng/mL)-induced proliferation of PASMCs from IPAH patients. Imatinib (1 µg/mL) did not induce apoptosis in quiescent IPAH-PASMCs, but it had a pro-apoptotic effect on IPAH-PASMCs stimulated with PDGF-BB. Imatinib did not induce apoptosis in normal control PASMCs with or without PDGF-BB stimulation. PDGF-BB induced phosphorylation of Akt at 15 min, and Akt phosphorylation was inhibited by imatinib in IPAH-PASMCs. Akt-I-1/2 (1 µmol/L), an Akt inhibitor, in the presence of PDGF-BB significantly increased apoptotic cells compared with the control condition. Thus, Akt-I-1/2 could mimic the effects of imatinib on PASMCs. CONCLUSION: Imatinib has anti-proliferative and pro-apoptotic effects on IPAH-PASMCs stimulated with PDGF. The inhibitory effect of imatinib on Akt phosphorylation induced by PDGF plays an important role in the pro-apoptotic effect.

Elevated oxidative stress is associated with ventricular fibrillation episodes in patients with Brugada-type electrocardiogram without SCN5A mutation.

BACKGROUND: Brugada syndrome is a disease known to cause ventricular fibrillation with a structurally normal heart and is linked to SCN5A gene mutation. However, the mechanism by which ventricular fibrillation develops in cases of Brugada-type electrocardiogram without SCN5A mutation has remained unclear. Recently, oxidative stress has been implicated in the pathophysiology of cardiac arrhythmia. We also investigated oxidative stress levels in the myocardia of patients with Brugada-type electrocardiogram. METHODS: Endomyocardial biopsy samples were obtained from 68 patients with Brugada-type electrocardiogram (66 males and two females). We performed histological and immunohistochemical analyses for CD45, CD68, and 4-hydroxy-2-nonenal-modified protein, which is a major lipid peroxidation product. RESULTS: SCN5A mutation was detected in 14 patients. Ventricular fibrillation was documented in three patients with SCN5A mutation and in 11 without SCN5A mutation. In patients with SCN5A mutation, 4-hydroxy-2-nonenal-modified protein-positive area was not significantly different between the documented ventricular fibrillation (VF) group (VF+ group) and the group without documented VF (VF- group). However, in patients without SCN5A, the area was significantly larger in the VF+ group than that in the VF- group (P<.05). All other parameters (fibrosis area, CD45, and CD68) were not different between the VF+ and VF- group in both SCN5A+ and SCN5A- patients. CONCLUSION: Oxidative stress is elevated in the myocardium of patients with Brugada-type electrocardiogram who have VF episodes and do not have SCN5A gene mutations. Oxidative stress may be associated with the occurrence of VF in patients with Brugada-type electrocardiogram without SCN5A mutation.