Supramolecular nanoparticles based on elastin-like peptides modified capsid protein as drug delivery platform with enhanced cancer chemotherapy efficacy.

Cancer, a prevalent disease posing significant threats to human health and longevity, necessitates effective therapeutic interventions. Chemotherapy has emerged as a primary strategy following surgical procedures for combating most malignancies. Despite the considerable efficacy of conventional chemotherapeutic agents against cancer cells, their utility is hindered by profound challenges such as multidrug resistance and deleterious toxic side effects, thereby limiting their systemic application. To tackle these challenges, we have devised a promising nanomedicine platform based on a plant virus. Specifically, we have selected the cowpea melanoma mottled virus (CCMV) as our nano-delivery system owing to its monodisperse and homogeneous size, as well as its intrinsic ability for controlled self-assembly. Leveraging the potential of this platform, we have engineered CCMV-based nanoparticles functionalized with elastin-like peptides (ELPs) at their N-terminal region. The target protein, CP-ELP, was expressed via E.coli, enabling encapsulation of the model drug DOX upon structural domain modification of the protein. The resulting nanoparticles exhibit uniform size distribution, facilitating efficient internalization by tumor cells and subsequent intracellular drug release, leading to enhanced antitumor efficacy. In addition, EVLP@DOX nanoparticles were found to activate immune response of tumor microenvironment in vivo, which further inhibiting tumor growth. Our designed nanoparticles have also demonstrated remarkable therapeutic effectiveness and favorable biological safety profiles in both murine melanoma and colorectal cancer models.

[Cefoxitin plus levofloxacin for prevention of severe infection after transrectal prostate biopsy].

OBJECTIVE: To evaluate the effect of cefoxitin prophylactic in reducing the incidence of severe infection after transrectal prostate biopsy (TRPB). METHODS: This retrospective study included 155 cases of TRPB with a 5-day administration of oral levofloxacin at 200 mg bid (the control group) and another 167 cases with a 3-day administration of oral levofloxacin at the same dose plus intravenous cefoxitin at 2.0 g 2 hours before TRPB (the experimental group) according to the distribution characteristics of drug-resistance bacteria in our department. The patients of the control and experimental groups were aged (68.68 ± 8.12) and (68.72 ± 7.51) years, with PSA levels of (19.78 ± 21.57) and (21.15 ± 42.63) µg/L, involving (11.68 ± 1.44) and (11.77±1.02) biopsy cores, respectively. Comparisons were made between the two groups of patients in the incidence rate of severe infection, which was defined as lower urinary track symptoms plus the systemic inflammatory response syndrome (SIRS) within 7 days after TRPB. RESULTS: The incidence rate of postoperative severe infection was significantly lower in the experimental group than in the control (0.6% ï¼»1/167ï¼½ vs 5.8% ï¼»9/155ï¼½, P < 0.05). Blood cultures revealed positive E-coli strains in 6 cases in the control group, including 5 ESBL-positive and 4 quinolone-resistant and amikacin-sensitive cases, all sensitive to cefoxitin, cefoperazone/sulbactam and imipenem. The only one case of severe infection was shown to be negative in blood culture. CONCLUSIONS: Preoperative intravenous administration of cefoxitin according to the specific distribution characteristics of drug-resistance bacteria can significantly reduce the incidence of severe infection after TRPB.

A New Chimeric Natriuretic Peptide, CNAAC, for the Treatment of Left Ventricular Dysfunction after Myocardial Infarction.

An innovative natriuretic peptide analog named CNAAC (structurally consisting of the C-terminus and ring of ANP and the N-terminus of CNP) that has been shown to exhibit potent vasodilatory, diuretic, and hypotensive effects in our previous study was evaluated for the treatment of left ventricular dysfunction following myocardial infarction. The temporal relaxation effect and metabolic status of CNAAC were determined. A myocardial ischemic model was established. Rats were randomly divided into Sham, MI, MI-ANP, MI-CNP, MI-VNP, and MI-CNAAC groups. Humoral factors were measured; echocardiography and hemodynamics methods were employed to assess the cardiac function at the fourth week after modeling. The results showed that CNAAC had a potent relaxant effect and longer duration of action than ANP, CNP, or VNP. The stability of CNAAC in blood was higher than other three NPs. Four weeks of NP administration ameliorated diastolic and systolic dysfunction, the hypertrophic index, myocardial fibrosis, and infarct size; it also restored the abnormal changes in humoral factors. These results demonstrate that CNAAC has a potent cardioprotective effect against left ventricular dysfunction after myocardial infarction. The results may lay the foundation for the clinical application of this newly designed NP chimera in the treatment and prevention of heart failure.

[Circumcision versus the foreskin-deglove plus shaft-fix procedure for phimosis or redundant prepuce in obese adult patients].

OBJECTIVE: To compare the clinical effects of circumcision and the foreskin-deglove plus shaft-fix (FDSF) procedure in the treatment of phimosis or redundant prepuce in obese adult males (body mass index [BMI] ≥ 28 kg/m²). METHODS: Forty-four obese adult men with phimosis or redundant prepuce underwent circumcision (n = 24) or FDSF (n = 20) according to their own wishes. The patients in the circumcision and FDSF groups were aged (26.38 ± 4.24) and (26.90 ± 3.14) years, with BMIs of (27.77 ± 0.77) and (28.07 ± 2.28) kg/m² and penis lengths of (3.51 ± 0.46) and (3.50 ± 0.59) cm, respectively. The operations were performed under local anesthesia with lidocaine plus ropivacaine mesylate. RESULTS: The operation time of circumcision was (28.04 ± 2.65) min and that of FDSF was (45.45 ± 3.49) min. At 6 months after surgery, normal penile erection was found in all the patients, the penis length was significantly longer in the FDSF than in the circumcision group ([5.01 ± 0.73] vs [3.70 ± 0.47] cm) , and the rate of satisfaction with penile appearance was markedly higher in the former than in the latter group (3.25 ± 0.71 vs 2.83 ± 0.56). CONCLUSION: The foreskin-deglove plus shaft-fix procedure under local anesthesia with lidocaine and ropivacaine mesylate may achieve desirable penile erection and appearance in the treatment of phimosis or redundant prepuce in obese adult patients.

κ-Opioid Receptor Stimulation Improves Endothelial Function via Akt-stimulated NO Production in Hyperlipidemic Rats.

This study was designed to investigate the effect of U50,488H (a selective κ-opioid receptor agonist) on endothelial function impaired by hyperlipidemia and to determine the role of Akt-stimulated NO production in it. Hyperlipidemic model was established by feeding rats with a high-fat diet for 14 weeks. U50,488H and nor-BNI (a selective κ-opioid receptor antagonist) were administered intraperitoneally. In vitro, the involvement of the PI3K/Akt/eNOS pathway in the effect of U50,488H was studied using cultured endothelial cells subjected to artificial hyperlipidemia. Serum total cholesterol and low-density lipoprotein cholesterol concentrations dramatically increased after high-fat diet feeding. Administration of U50,488H significantly alleviated endothelial ultrastructural destruction and endothelium-dependent vasorelaxation impairment caused by hyperlipidemia. U50,488H also increased Akt/eNOS phosphorylation and serum/medium NO level both in vivo and in vitro. U50,488H increased eNOS activity and suppressed iNOS activity in vivo. The effects of U50,488H were abolished in vitro by siRNAs targeting κ-opioid receptor and Akt or PI3K/Akt/eNOS inhibitors. All effects of U50,488H were blocked by nor-BNI. These results demonstrate that κ-opioid receptor stimulation normalizes endothelial ultrastructure and function under hyperlipidemic condition. Its mechanism is related to the preservation of eNOS phosphorylation through activation of the PI3K/Akt signaling pathway and downregulation of iNOS expression/activity.

Lacidipine attenuates TNF-α-induced cardiomyocyte apoptosis.

This study was designed to investigate whether lacidipine elicited a protective role on cardiomyocyte against apoptosis induced by TNF-α. Neonatal rat cardiomyocytes were randomly assigned into different groups. TUNEL staining was utilized to detect apoptosis, and caspase-3 and caspse-12 were determined. To explore the underlying mechanism, Z-ATAD-FMK (a selective caspase-12 inhibitor) was used to identify the key molecule involved. TNF-α increased caspase-3 expression, which was mediated by increased caspase-12 expression. In the meantime, apoptosis was significantly induced by TNF-α. Lacidipine lowered caspase-12 and caspase-3 expression, and cardiomyocyte apoptosis induced by TNF-α. The results suggest that lacidipine attenuates TNF-α -induced apoptosis via inhibition of caspase-12 and caspase-3 successively.

Silencing the expression of Cbl-b enhances the immune activation of T lymphocytes against RM-1 prostate cancer cells in vitro.

BACKGROUND: The ubiquitin ligase Cbl-b potently modulates T lymphocyte immune responses and is critical in modulating tumor-induced immunosuppression. The influence of Cbl-b in modulating T lymphocyte activity against prostate cancer remains ill defined. We have determined the effects of silencing Cbl-b expression in T lymphocytes and their subsequent cytotoxic activity against prostate cancer cells. METHODS: T lymphocytes were isolated from the spleens of C57BL/6 mice. Lipofectamine-directed transfection of T lymphocytes with specific small interfering RNA (siRNA) silenced Cbl-b expression, which was confirmed by Western immunoblotting. The siRNA species were chosen that promoted the greatest transfection efficiency and dampened Cbl-b expression in T lymphocytes. The expression of CD69, CD25, and CD71 by the transfected T lymphocytes was determined by flow cytometry. T lymphocyte proliferation was assessed by CCK-8 assay. Enzyme-linked immunosorbent assay (ELISA) was used to measure the secretion of interleukin (IL)-2, interferon (IFN)-γ, and tumor necrosis factor (TNF)-ß. The objective was to compare the cytotoxic activity of transfected T lymphocytes and nontransfected (i.e., negative control) T lymphocytes against the murine prostate cancer cell line target RM-1 in vitro. RESULTS: We selected a specific siRNA that decreased T lymphocyte Cbl-b expression to 15%. The siRNA-transfected T lymphocytes showed higher proliferation; higher CD69, CD25, and CD71 expression (p < 0.001); and higher IL-2, IFN-γ, and TNF-ß secretion (p < 0.05), compared to the nontransfected cells. Transfected T lymphocytes were also more potent at killing RM-1 prostate cancer cells, compared to the negative control in vitro. CONCLUSION: Silencing Cbl-b significantly enhanced T lymphocyte function and T lymphocyte cytotoxicity activity against a model prostate cancer cell line in vitro. This study suggests a potentially novel immunotherapeutic strategy against prostate cancer.

A Changing Healthcare System Model: The Effectiveness of Knowledge, Attitude, and Skill of Nursing Assistants Who Attend Senile Dementia Patients in Nursing Homes in Xi'an, China - A Questionnaire Survey.

BACKGROUND: In 2010, China had an elderly population of 1.78 billion people. As in other societies around the world, China is facing a growing challenge in providing care for its elderly citizens. Ensuring the highest quality of care for elderly patients, many of whom have senile dementia, is directly related to the performance of nursing assistants. METHODS: With the goal of investigating the knowledge, attitudes, and skills of nursing assistants who care for senile dementia patients in nursing homes in Xi'an, China, we distributed a survey and analyzed the responses. RESULTS: Nursing assistants showed dedication and sincerity in their care for senile dementia patients. However, their performances in the categories of life nursing and mental nursing reveal room for improvement. Further, the nursing assistants did not display adequate knowledge about senile dementia. Based on survey results, the knowledge of the nursing assistants concerning nursing safety was comparatively adequate. CONCLUSION: Nursing assistants who care for senile dementia patients in nursing homes in Xi'an, China, require further training that expands their knowledge and increases their capabilities. We recommend that nursing homes in Xi'an offer a standardized professional nurse/nurse assistant training course that focuses on care for elderly patients with senile dementia.

Chrebp regulates the transcriptional activity of androgen receptor in prostate cancer.

Androgen receptor (AR), a member of nuclear hormone receptor, plays an essential role in the initiation and progression of prostate cancer (PCa). In the present study, by way of immunoprecipitation followed by mass spectrometry (IP/MS) system, we found that carbohydrate-responsive element-binding protein (Chrebp), a glucose sensor in normal and cancer cells, interacted with AR in LNCaP cells. The interaction was further confirmed by coimmunoprecipitation analysis. Besides, Chrebp is required for the optimal transcriptional activity of AR in promoting the transcription of the prostate-specific antigen (PSA) promoter and messenger RNA (mRNA) expression. Consistently, knockdown of Chrebp using small interfering RNA (siRNA) in LNCaP cells reduced endogenous PSA levels. Together, our study demonstrates that Chrebp interacts with AR and regulates its transcriptional activity.

Κ-opioid receptor stimulation improves endothelial function in hypoxic pulmonary hypertension.

The present study was designed to investigate the effect of κ-opioid receptor stimulation with U50,488H on endothelial function and underlying mechanism in rats with hypoxic pulmonary hypertension (HPH). Chronic hypoxia-induced HPH was simulated by exposing the rats to 10% oxygen for 2 wk. After hypoxia, mean pulmonary arterial pressure (mPAP), right ventricular pressure (RVP) and right ventricular hypertrophy index (RVHI) were measured. Relaxation of pulmonary artery in response to acetylcholine (ACh) was determined. Expression and activity of endothelial nitric oxide (NO) synthase (eNOS) and inducible NO synthase (iNOS) with NO production, total antioxidant capacity (T-AOC), gp91(phox) expression and nitrotyrosine content were measured. The effect of U50,488H administration during chronic hypoxia was investigated. Administration of U50,488H significantly decreased mPAP and right ventricular hypertrophy as evidenced by reduction in RVP and RVHI. These effects were mediated by κ-opioid receptor. In the meantime, treatment with U50,488H significantly improved endothelial function as evidenced by enhanced relaxation in response to ACh. Moreover, U50,488H resulted in a significant increase in eNOS phosphorylation, NO content in serum, and T-AOC in pulmonary artery of HPH rats. In addition, the activity of eNOS was enhanced, but the activity of iNOS was attenuated in the pulmonary artery of chronic hypoxic rats treated with U50,488H. On the other hand, U50,488H markedly blunted HPH-induced elevation of gp91(phox) expression and nitrotyrosine content in pulmonary artery, and these effects were blocked by nor-BNI, a selective κ-opioid receptor antagonist. These data suggest that κ-opioid receptor stimulation with U50,488H improves endothelial function in rats with HPH. The mechanism of action might be attributed to the preservation of eNOS activity, enhancement of eNOS phosphorylation, downregulation of iNOS activity and its antioxidative/nitrative effect.

κ-opioid receptor activation prevents against arrhythmias by preserving Cx43 protein via alleviation of intracellular calcium.

κ-opioid receptor (κ-OR) activation with U50,488H, a selective κ-OR agonist, has been previously demonstrated to prevent against cardiac arrhythmias via stabilizing the synthesis and degradation of an integral membrane protein, Cx43, in gap junctions. However, the exact prevention mechanism remains unclear. The present study tested the hypothesis that the kappa OR agonist U50,488H mediates the prevention of arrhythmia through the regulation of intracellular calcium leading to the preservation of Cx43 protein. By performing electrocardiogram monitoring and immunoblotting in isolated Langendorff-perfused rat hearts, high concentrations of calcium-perfused rat hearts exhibited increased cardiac arrhythmias. Diminished expression of Cx43 protein was observed. The utilization of a whole-cell patch clamp technique revealed that U50,488H inhibited L-type calcium current in single ventricular myocytes in a dose-dependent manner. These effects were blocked by nor-binaltorphimine, potent and selective κ-OR antagonists. Administration of U50,488H before myocardial ischemia resulted in an attenuated of total arrhythmia scores. The attenuation effect was blocked by nor-binaltorphimine. The attenuation effect was antagonized both by Bay K8644, a L-type calcium channel agonist, and also by the Cx43 uncoupler heptanol. Finally, immunoblotting data demonstrated that the preservation of Cx43 protein conferred by U50,488H was reversed in the presence of Bay K8644. In summary, the present study demonstrates κ-OR activation with U50,488H may confer antiarrhythmic effects via modulation of the calcium-Cx43 pathway.

Vasculoprotective effect of U50,488H in rats exposed to chronic hypoxia: role of Akt-stimulated NO production.

Impairment of pulmonary endothelium function in the pulmonary artery is a direct result of chronic hypoxia. This study is to investigate the vasculoprotective effects of U50,488H (a selective κ-opioid receptor agonist) and its underlying mechanism in hypoxia-induced pulmonary artery endothelial functional injury. Chronic hypoxia was simulated by exposing the rats to 10% oxygen for 2 wk. After hypoxia, right ventricular pressure (RVP) and right ventricular hypertrophy index (RVHI) were measured. The pulmonary vascular dysfunction, effect of nitric oxide synthase inhibitor (l-NAME) on the relaxation of U50,488H, and level of nitric oxide (NO) were determined. In vitro, the signaling pathway involved in the anti-apoptotic effect of U50,488H was investigated. Cultured endothelial cells were subjected to simulated hypoxia, and cell apoptosis was determined by TUNEL staining. U50,488H (1.25 mg/kg) significantly reduced RVP and RVHI in hypoxia. U50,488H markedly improved both pulmonary endothelial function (maximal vasorelaxation in response to ACh: 74.9 ± 1.8%, n = 6, P <0.01 vs. hypoxia for 2 wk group) and increased total NO production (1.65 fold). U50,488H relaxed the pulmonary artery rings of the hypoxic rats. This effect was partly abolished by l-NAME. In cells, U50,488H both increased NO production and reduced hypoxia-induced apoptosis. Moreover, pretreatment with nor-binaltorphimine (nor-BNI, a selective κ-opioid receptor antagonist), PI3K inhibitor, Akt inhibitor or l-NAME almost abolished anti-apoptotic effect exerted by U50,488H. U50,488H resulted in increases in Akt and eNOS phosphorylation. These results demonstrate that pretreatment with U50,488H attenuates hypoxia-induced pulmonary vascular endothelial dysfunction in an Akt-dependent and NO-mediated fashion.

Development of a rat respiratory mask and its application in experimental chronic myocardial ischaemia.

In addressing the challenge of the low survival rates of rats with myocardial ischaemia, we developed a novel respiratory mask. We tested this mask on the rat model. We gave attention to several features of the mask: (1) shape, (2) size, (3) inlet, (4) outlet, (5) compatibility between rat head and the mask, (6) connection between mask and ventilator. We found certain features, especially to influence mask efficacy. These features include: mask shape, mask inlet and outlet, mask connection to the respiratory machine, mask mount on the rat head. We examined the rat mask in a model of chronic myocardial ischaemia; our model was the ligation of the coronary artery. The rats with the masks experienced an increase in survival by a factor of 50-90% compared with rats deprived of the masks. Towards the examination of myocardial ischaemia, our new mask may offer a platform replete with both efficiency and stability.

[Effect of compound nutrients on acute immobilization and cold water-immersion stress-induced changes of Th1/Th2 cytokines].

AIM: To investigate the effect of compound nutrients on Th1/Th2 imbalance caused by changes in cytokines of Th cell subsets, interleukin (IL)-2, IL-6 and TNF-α, in rats with acute immobilization and cold water-immersion stress. METHODS: Male SD rats were randomly assigned to three groups including normal control group (C), acute stress group (S) and acute stress+compound nutrients group (S+CN). Stress procedure was the acute immobilization and cold water-immersion. The stress rats were fed water (Group S) or compound nutrient liquid (Group S+CN) by a feeding needle 1 week before acute stress, and then restrained and immersed in cold water for 30 min. The control rats were given water in the same way without stress stimulation. The rats were killed and blood samples were collected 0, 30, 60 and 120 min after stress, respectively. Serum was separated by centrifugation and stored at -70 DegreesCelsius until assayed. The serum levels of IL-2, IL-6 and TNF-α were analyzed by an enzyme-linked immunosorbent assay (ELISA) kit. RESULTS: Acute immobilization and cold water-immersion stress reduced IL-2 level, and increased IL-6 and TNF-α level at different time points (0, 30, 60 and 120 min) after stress, which was most obvious at 30 min. Oral administration (gavage) of compound nutrients was found to moderate the acute immobilization and cold water-immersion stress-induced changes in serum IL-2, IL-6 and TNF-α, which was also most significant at 30 min after stress. CONCLUSION: Complex nutrients can significantly alleviate the changes of Th1/Th2 cytokines in stress rats, including IL-2, IL-6 and TNF-α, which suggests that compound nutrients can improve the immune regulation function of stress rats and restore Th1/Th2 balance. Compound nutrients might enhance the body's anti-stress ability and lighten the stress-related damage, thus being a possible candidate for the therapeutic modulation of stress.

Resveratrol attenuates ischemia/reperfusion injury in neonatal cardiomyocytes and its underlying mechanism.

This study was designed to investigate whether Resveratrol (Res) could be a prophylactic factor in the prevention of I/R injury and to shed light on its underlying mechanism. Primary culture of neonatal rat cardiomyocytes were randomly distributed into three groups: the normal group (cultured cardiomyocytes were in normal conditions), the I/R group (cultured cardiomyocytes were subjected to 2 h simulated ischemia followed by 4 h reperfusion), and the Res+I/R group (100 µmol/L Res was administered before cardiomyocytes were subjected to 2 h simulated ischemia followed by 4 h reperfusion). To test the extent of cardiomyocyte injury, several indices were detected including cell viability, LDH activity, Na(+)-K(+)-ATPase and Ca(2+)-ATPase activity. To test apoptotic cell death, caspase-3 activity and the expression of Bcl-2/Bax were detected. To explore the underlying mechanism, several inhibitors, intracellular calcium, SOD activity and MDA content were used to identify some key molecules involved. Res increased cell viability, Na(+)-K(+)-ATPase and Ca(2+)-ATPase activity, Bcl-2 expression, and SOD level. While LDH activity, capase-3 activity, Bax expression, intracellular calcium and MDA content were decreased by Res. And the effect of Res was blocked completely by either L-NAME (an eNOS inhibitor) or MB (a cGMP inhibitor), and partly by either DS (a PKC inhibitor) or Glybenclamide (a K(ATP) inhibitor). Our results suggest that Res attenuates I/R injury in cardiomyocytes by preventing cell apoptosis, decreasing LDH release and increasing ATPase activity. NO, cGMP, PKC and K(ATP) may play an important role in the protective role of Res. Moreover, Res enhances the capacity of anti-oxygen free radical and alleviates intracellular calcium overload in cardiomyocytes.

Deletion of RBP-J in adult mice leads to the onset of aortic valve degenerative diseases.

Transcription factor RBP-J-mediated Notch signaling has been implicated in several inherited cardiovascular diseases including aortic valve diseases (AVD). But whether Notch signal plays a role in AVD in adults has been unclear. This study aims to test whether the deletion of RBP-J in adult mice would lead to AVD and to investigate the underlying mechanisms. Cre-LoxP-mediated gene deletion was employed to disrupt Notch signal in adult mice. Immunofluorescence and electron microscope observations showed that deletion of RBP-J in adult mice led to early morphological changes of AVD. The size of aortic valve was enlarged. The endothelial homeostasis was perturbed, probably due to the up-regulation of VEGFR2. The endothelial cells exhibited increased proliferation and loose endothelial junctions. The valvular mesenchyme displayed significant fibrosis, consistent with the up-regulation of TGF-ß1 and activation of endothelial-mesenchymal transition. We observed melanin-producing cells in aortic valves. The number of melanin-producing cells increased significantly, and their location changed from the mesenchyme to subendothelial layer of valve cusps in RBP-J deficient mice. These results suggest that RBP-J-mediated Notch signaling in aortic valves may be critically involved in valve homeostasis and valve diseases as well. These findings will be helpful for the understanding of the molecular mechanisms of AVD in adults.

Endogenous κ-opioid peptide mediates the cardioprotection induced by ischemic postconditioning.

The aim of this study was to investigate the underlying mechanism that dynorphin, an endogenous kappa opioid receptor (κ-OR) agonist, triggers antiapoptotic effect of postconditioning (Postcon). In addition to vehicle treatment, Sprague Dawley rats (n = 6) underwent a 30-minute left anterior descending occlusion followed by 2 hours of reperfusion with or without a Postcon stimulus. The selective κ-OR antagonist nor-binaltorphimine (Nor-BNI) was administered intravenously 5 minutes before reperfusion. Infarct size was determined by using 2,3,5-triphenyltetrazolium chloride staining. Blood plasma concentrations of creatine kinase (CK) and lactate dehydrogenase (LDH) and myocardial caspase-3 activity were analyzed spectrophotometrically. Myocardial apoptosis was analyzed by the detection of terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end labeling. Immunoreactive dynorphin in blood serum and myocardium was measured by means of an antigen-competitive enzyme-linked immunosorbent assay. Infarction size, caspase-3 activity, apoptotic index, and CK and LDH levels were significantly higher in the ischemic/reperfusion group than in the vehicle group (P < 0.01). Postcon significantly reduced infarction size, caspase-3 activity, apoptotic index, CK and LDH levels (P < 0.01 vs. ischemic/reperfusion). Dynorphin content significantly increased after Postcon (P < 0.01). All the effects described above were abolished by Nor-BNI, with the exception of dynorphin content. We found that cardiac protection and antiapoptotic effect of Postcon is mediated by the activation of κ-OR. Effect of Postcon is mediated, at least partially, by enhanced dynorphin expression.

Doppler flow spectra of the superior vena cava in a rat model of chronic pulmonary hypertension.

The aim of this study was to explore the changes of the Doppler flow spectra of the superior vena cava (SVC) in a rat model of chronic pulmonary hypertension (PH). Thirty-two rats were injected with monocrotaline (MCT) to establish a model of chronic PH. Eight rats from the control group had a sham operation by injecting Dulbecco's phosphate-buffered solution. Serial echocardiographic parameters of the SVC were analysed four weeks after treating with MCT or placebo, and the relationship was analysed between the Doppler flow spectra of SVC and the pulmonary arterial systolic pressure (PASP). PH models were successfully established in 29 rats. The right ventricular systolic pressure, mean pulmonary arterial pressure and PASP in the PH group were significantly higher than those in the sham group at 28 days (P < 0.001). The ratios of SVC maximum reverse peak flow velocity/maximum systolic peak flow velocity (VAr/VS) and maximum reverse peak velocity time integral/maximum systolic peak velocity time integral (VTIAr/VTIS) increased significantly (P < 0.05) after MCT injection. These results demonstrate that echocardiography can be used to monitor the haemodynamic changes in SVC in MCT-induced chronic PH rat models. The ratios of VAr/VS and VTIAr/VTIS may be sensitive indices for evaluating PH.

Antiarrhythmic effect mediated by κ-opioid receptor is associated with Cx43 stabilization.

OBJECTIVE: Acute myocardial ischemia induces electrical and chemical uncoupling of gap junctions, which contributes to conduction abnormalities and re-entrant arrhythmias. We tested the hypothesis that structure and function of Connexin43 may vibrate during acute myocardial ischemia and reperfusion and κ-opioid receptor stimulation may stabilize the alteration of Connexin43. DESIGN: An animal intervention study was conducted with comparison to a control group. SETTING: University preclinical research laboratory. SUBJECTS: Age-, weight-, and sex-matched Sprague-Dawley rats. INTERVENTIONS: Adult rat hearts were subjected to ischemia or ischemia/reperfusion, which was induced by temporary occlusion of the left main coronary artery. U50488H was given 10 mins before tissue specimens were taken or before ischemia (1.5 mg/kg, intravenous) and nor-BNI was given 15 mins before tissue specimens were taken or before ischemia (2 mg/kg, intravenous). Tissue samples came from left ventricular myocardium of the rat hearts. MEASUREMENTS AND MAIN RESULTS: Electrocardiogram, immunohistochemistry, immunoblotting, and reverse transcription-polymerase chain reaction were used to measure changes of arrhythmias, protein, and gene expression of Connexin43, respectively. κ-opioid receptor activation with U50 decreased arrhythmia in a model of myocardial ischemia and reperfusion. In normal hearts, immunohistochemical data showed reduced amount and lateralization of Connexin43 induced by κ-opioid receptor activation, whereas immunoblotting data demonstrated no significant changes between control and U50 group. During ischemia, however, Connexin43 protein underwent dephosphorylation and degradation, and Connexin43 mRNA was upregulated. These alterations were significantly attenuated on κ-opioid receptor stimulation. During ischemia and reperfusion, Connexin43 protein underwent dephosphorylation and degradation and recovered slowly during reperfusion. Activation of κ-opioid receptor accelerated recovery of phosphorylated and total Connexin43. CONCLUSIONS: In normal rat hearts, Connexin43 translocates from intercellular junctions to intracellular locations on κ-opioid receptor activation. In rat hearts experiencing acute myocardial ischemia and reperfusion, protein and gene expression of Connexin43 undergo vibration. This phenomenon is stabilized when κ-opioid receptor is activated and by the fact that κ-opioid receptor produces antiarrhythmic effects.

Modulation of intracellular calcium transient in response to beta-adrenoceptor stimulation in the hearts of 4-wk-old rats during simulated weightlessness.

Modulation of intracellular calcium ([Ca(2+)](i)) transient in response to beta-adrenoceptor stimulation in the hearts of hindlimb unweighted (HLU) rats during simulated weightlessness has not been reported. In the present study, we adopted the rat tail suspension for 4 wk to simulate weightlessness. Effects of simulated microgravity on beta-adrenoceptor responsiveness were then studied. Mean arterial blood pressure, left ventricular pressure (LVP), systolic function [maximum positive change in pressure over time (+dP/dt(max))], and diastolic function [maximum negative change in pressure over time (-dP/dt(max))] were monitored during the in vivo experiment. beta-Adrenoceptor density was quantitated by radioactive ligand binding. Single rat ventricular myocyte was obtained by enzymatic dissociation method. +/-dP/dt(max), myocyte contraction, intracellular [Ca(2+)](i) transient, and L-type calcium current in response to beta-adrenoceptor stimulation with isoproterenol were measured. Compared with the control group, no significant changes were found in heart weight, body weight, and mean arterial blood pressure, whereas LVP and +/-dP/dt(max) were significantly reduced. LVP and +/-dP/dt(max) were significantly attenuated in the HLU group in response to isoproterenol administration. In the in vitro study, the beta-adrenoceptor density was unchanged. Effects of isoproterenol on electrically induced single-cell contraction and [Ca(2+)](i) transient in myocytes of ventricles in HLU rats were significantly attenuated. The enhanced L-type Ca(2+) current elicited by isoproterenol in cardiomyocytes was significantly decreased in the HLU group. The above results indicate that impaired function of L-type Ca(2+) current and decreased [Ca(2+)](i) transient cause the depressed responsiveness of the beta-adrenoceptor stimulation, which may be partially responsible for the depression of cardiac function.