Clinical risk score for postoperative pneumonia following heart valve surgery.

BACKGROUND: Postoperative pneumonia (POP) is one of the most common infections following heart valve surgery (HVS) and is associated with a significant increase in morbidity, mortality, and health care costs. This study aimed to identify the major risk factors associated with the occurrence of POP following HVS and to derive and validate a clinical risk score. METHODS: Adults undergoing open HVS between January 2016 and December 2019 at a single institution were enrolled in this study. Patients were randomly assigned to the derivation and validation sets at 1:1 ratio. A prediction model was developed with multivariable logistic regression analysis in the derivation set. Points were assigned to independent risk factors based on their regression coefficients. RESULTS: POP occurred in 316 of the 3853 patients (8.2%). Multivariable analysis identified ten significant predictors for POP in the derivation set, including older age, smoking history, chronic obstructive pulmonary disease, diabetes mellitus, renal insufficiency, poor cardiac function, heart surgery history, longer cardiopulmonary bypass, blood transfusion, and concomitant coronary and/or aortic surgery. A 22-point risk score based on the multivariable model was then generated, demonstrating good discrimination (C-statistic: 0.81), and calibration (Hosmer-Lemeshow χ2 = 8.234, P = 0.312). The prediction rule also showed adequate discriminative power (C-statistic: 0.83) and calibration (Hosmer-Lemeshow χ2 = 5.606, P = 0.691) in the validation set. Three risk intervals were defined as low-, medium-, and high-risk groups. CONCLUSION: We derived and validated a 22-point risk score for POP following HVS, which may be useful in preventive interventions and risk management. TRIAL REGISTRATION: Chictr.org, ChiCTR1900028127; http://www.chictr.org.cn/showproj.aspx?proj=46932.

Type 3 muscarinic acetylcholine receptor stimulation is a determinant of endothelial barrier function and adherens junctions integrity: role of protein-tyrosine phosphatase 1B.

The main purpose of this study was to investigate whether type 3 muscarinic acetylcholine receptor (M3R) dysfunction induced vascular hyperpermeability. Transwell system analysis showed that M3R inhibition by selective antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) and small interfering RNA both increased endothelial permeability. Using coimmunoprecipitation and Western blot assay, we found that M3R inhibition increased VE-cadherin and ß-catenin tyrosine phosphorylation without affecting their expression. Using PTP1B siRNA, we found that PTP1B was required for maintaining VE-cadherin and ß-catenin protein dephosphorylation. In addition, 4-DAMP suppressed PTP1B activity by reducing cyclic adenosine monophosphate (cAMP), but not protein kinase Cα (PKCα). These data indicate that M3R preserves the endothelial barrier function through a mechanism potentially maintaining PTP1B activity, keeping the adherens junction proteins (AJPs) dephosphorylation.

Effects of the natural flavone trimethylapigenin on cardiac potassium currents.

The natural flavones and polymethylflavone have been reported to have cardiovascular protective effects. In the present study, we determined whether quecertin, apigenin and their methylated compounds (3,7,3',4'-tetramethylquecertin, 3,5,7,3',4'-pentamethylquecertin, 7,4'-dimethylapigenin, and 5,7,4'-trimethylapigenin) would block the atrial specific potassium channel hKv1.5 using a whole-cell patch voltage-clamp technique. We found that only trimethylapigenin showed a strong inhibitory effect on hKv1.5 channel current. This compound suppressed hKv1.5 current in HEK 293 cell line (IC50=6.4 µM), and the ultra-rapid delayed rectify K⁺ current I(Kur) in human atrial myocytes (IC50=8.0 µM) by binding to the open channels and showed a use- and frequency-dependent manner. In addition, trimethylapigenin decreased transient outward potassium current (I(to)) in human atrial myocytes, inhibited acetylcholine-activated K⁺ current (IC50=6.8µM) in rat atrial myocytes. Interestingly, trimethylapigenin had a weak inhibition of hERG channel current. Our results indicate that trimethyapigenin significantly inhibits the atrial potassium currents hKv1.5/I(Kur) and I(KACh), which suggests that trimethylapigenin may be a potential candidate for anti-atrial fibrillation.

Impaired thymic export and apoptosis contribute to regulatory T-cell defects in patients with chronic heart failure.

OBJECTIVE: Animal studies suggest that regulatory T (T(reg)) cells play a beneficial role in ventricular remodeling and our previous data have demonstrated defects of T(reg) cells in patients with chronic heart failure (CHF). However, the mechanisms behind T(reg-)cell defects remained unknown. We here sought to elucidate the mechanism of T(reg-)cell defects in CHF patients. METHODS AND RESULTS: We performed flow cytometry analysis and demonstrated reduced numbers of peripheral blood CD4(+)CD25(+)FOXP3(+)CD45RO(-)CD45RA(+) naïve T(reg) (nT(reg)) cells and CD4(+)CD25(+)FOXP3(+)CD45RO(+)CD45RA(-) memory T(reg) (mT(reg)) cells in CHF patients as compared with non-CHF controls. Moreover, the nT(reg)/mT(reg) ratio (p<0.01), CD4(+)CD25(+)FOXP3(+)CD45RO(-) CD45RA(+)CD31(+) recent thymic emigrant T(reg) cell (RTE-T(reg)) frequency (p<0.01), and T-cell receptor excision circle levels in T(reg) cells (p<0.01) were lower in CHF patients than in non-CHF controls. Combined annexin-V and 7-AAD staining showed that peripheral T(reg) cells from CHF patients exhibited increased spontaneous apoptosis and were more prone to interleukin (IL)-2 deprivation- and CD95 ligand-mediated apoptosis than those from non-CHF individuals. Furthermore, analyses by both flow cytometry and real-time polymerase chain reaction showed that T(reg)-cell frequency in the mediastinal lymph nodes or Foxp3 expression in hearts of CHF patients was no higher than that of the non-CHF controls. CONCLUSION: Our data suggested that the T(reg)-cell defects of CHF patients were likely caused by decreased thymic output of nascent T(reg) cells and increased susceptibility to apoptosis in the periphery.

Functional ion channels in mouse cardiac c-kit(+) cells.

Cardiac c-kit(+) cells are generally believed to be the major population of stem/progenitor cells in the heart and can be used as a cell source for cardiomyoplasty; however, the cellular electrophysiological properties are not understood in this type of cells. The present study was designed to investigate functional ion channels in undifferentiated mouse cardiac c-kit(+) cells using approaches of whole cell patch voltage clamp, RT-PCR, and cell proliferation assay. It was found that three types of ionic currents were present in mouse cardiac c-kit(+) cells, including a delayed rectifier K(+) current (IK(DR)) inhibited by 4-aminopyridine (4-AP), an inward rectifier K(+) current (I(Kir)) decreased by Ba(2+), and a volume-sensitive chloride current (I(Cl.vol)) inhibited by 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB). RT-PCR revealed that the corresponding ion channel genes, Kv1.1, Kv1.2, and Kv1.6 (for IK(DR)), Kir.1.1, Kir2.1, and Kir2.2 (likely responsible for I(Kir)), and Clcn3 (for I(Cl.vol)), were significant in mouse cardiac c-kit(+) cells. The inhibition of I(Cl.vol) with NPPB and niflumic acid, but not IK(DR) with 4-AP and tetraethylammonium, reduced cell proliferation and accumulated the cell progression at G(0)/G(1) phase in mouse cardiac c-kit(+) cells. Our results demonstrate that three types of functional ion channel currents (i.e., IK(DR), I(Kir), and I(Cl.vol)) are present in mouse cardiac c-kit(+) cells, and I(Cl.vol) participates in regulating cell proliferation.

[Heat-shock protein 70 may be a putative endogenous ligand of Toll-like receptor-4 of human monocytes].

OBJECTIVE: To explore the relation between human heat shock protein 70 (HSP70) and Toll-like receptor-4 (TLR4) in human monocytes. METHODS: Periphery blood mononuclear cells were isolated from the samples of healthy blood donors' whole blood and monocytes were prepared and cultured. HSP70 of the final concentrations of 2.5 microg/ml, 5.0 microg/ml, 7.5 microg/ml, and 10 microg/ml respectively was added; 6 hours later the concentration of TNF-alpha in the supernatant was detected. Another monocytes were cultured and HSP70 of the final concentration of 5.0 microg/ml was added and the concentrations of NF-kappaB were detected 0, 30, 60, and 120 minutes later respectively. TLR4 blocker of the final concentrations of 5 microg/ml, 20 microg/ml, and 30 microg/ml respectively was added into another culture for 30 minutes and 5.0 microg/ml HSP70 was added, then immunochemistry was used to detect the concentration of NF-kappaB 120 minutes after ELISA was used to detect the concentration of and TNF-alpha 8 hours later. In order to examine the influence of HSP70 on the TLR4 in the cytomembrane of monocytes, HSP70 of the final concentration of 5.0 microg/ml was added into the culture of monocytes for 0, 30, 60, and 120 minutes respectively then flow cytometry was used to detect the mean fluorescence intensity (MFI) of TLR4. RESULTS: HSP70 stimulation increased the TNF-a concentration in the supernatant dose-dependently. The percentages of NF-kappaB positive monocytes were 38 +/- 6, 67 +/- 12, and 54 +/- 12 30 min, 60 min, 120 min after HSP70 stimulation, all significantly higher than that at the beginning of experiment (17 +/- 6, P < 0.05, P < 0.01, and P < 0.01). The percentages of NF-kappaB positive monocytes were 39% +/- 4%, 32% +/- 6%, and 28% +/- 6% 120 minutes after anti-TLR4 mAb stimulation, all significantly lower than that of the control group (67% +/- 12%, all P < 0.05). TLR4 blocker of different concentrations significantly inhibited the TNF-alpha secretion by the monocytes (all P < 0.05). The MFI of TLR4 in the cytomembrane of monocyte was significantly down-regulated 60 minutes, especially 120 minutes, after the HSP70 stimulation in comparison with that before the stimulation (P < 0.05 and P < 0.01). CONCLUSION: TLR4 appears to be involved in HSP70-mediated activation of innate immunity.

Differential effects of tyrosine kinase inhibitors on volume-sensitive chloride current in human atrial myocytes: evidence for dual regulation by Src and EGFR kinases.

To determine whether protein tyrosine kinase (PTK) modulates volume-sensitive chloride current (I(Cl.vol)) in human atrial myocytes and to identify the PTKs involved, we studied the effects of broad-spectrum and selective PTK inhibitors and the protein tyrosine phosphatase (PTP) inhibitor orthovanadate (VO(4)(-3)). I(Cl.vol) evoked by hyposmotic bath solution (0.6-times isosmotic, 0.6T) was enhanced by genistein, a broad-spectrum PTK inhibitor, in a concentration-dependent manner (EC(50) = 22.4 microM); 100 microM genistein stimulated I(Cl.vol) by 122.4 +/- 10.6%. The genistein-stimulated current was inhibited by DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, 150 microM) and tamoxifen (20 microM), blockers of I(Cl.vol). Moreover, the current augmented by genistein was volume dependent; it was abolished by hyperosmotic shrinkage in 1.4T, and genistein did not activate Cl(-) current in 1T. In contrast to the stimulatory effects of genistein, 100 microM tyrphostin A23 (AG 18) and A25 (AG 82) inhibited I(Cl.vol) by 38.2 +/- 4.9% and 40.9 +/- 3.4%, respectively. The inactive analogs, daidzein and tyrphostin A63 (AG 43), did not alter I(Cl.vol). In addition, the PTP inhibitor VO(4)(-3) (1 mM) reduced I(Cl.vol) by 53.5 +/- 4.5% (IC(50) = 249.6 microM). Pretreatment with VO(4)(-3) antagonized genistein-induced augmentation and A23- or A25-induced suppression of I(Cl.vol). Furthermore, the selective Src-family PTK inhibitor PP2 (5 microM) stimulated I(Cl.vol), mimicking genistein, whereas the selective EGFR (ErbB-1) kinase inhibitor tyrphostin B56 (AG 556, 25 microM) reduced I(Cl.vol), mimicking A23 and A25. The effects of both PP2 and B56 also were substantially antagonized by pretreatment with VO(4)(-3). The results suggest that I(Cl.vol) is regulated in part by the balance between PTK and PTP activity. Regulation is complex, however. Src and EGFR kinases, distinct soluble and receptor-mediated PTK families, have opposing effects on I(Cl.vol), and multiple target proteins are likely to be involved.