Simple and easy method for chordal reconstruction during mitral valve repair

We describe a simple reproducible method for chordal replacement using expanded polytetrafluoroethylene sutures during a mitral valve repair. With this technique, fine length adjustments of the new chordae are easy to make and it is possible to tie the two ends of the suture securely without slippage.     

Effect of High Concentrations of Bile Acids on Cultured Hepatocytes

High concentrations of bile acids have been reported as injurious to hepatocytes. We report the influence of various combinations of bile acids on the liver-specific function of cultured rat hepatocytes. Using 4 bile acids (glycocholate [GC], taurocholate [TC], glycohenodeoxycholate [GCDC], and taurochenodeoxycholate [TCDC]), we obtained 6 bile-acid mixtures, each containing equal amounts of 2 bile acids (total bile acids [TBA], 2 m M ). Changes in gluconeogenesis, ureagenesis, DNA contents, medium alanine aminotransferase, and morphologies were compared among the paired bile acid compositions by measuring the C/CDC ratio ([GC + TC]/[GCDC + TCDC]) of each. In terms of their relative impairments of ureagenesis from greatest to least, the acids were GCDC, TCDC, and GC, which was almost the same as TC. When the C/CDC ratio was 0, the values of all parameters measured deteriorated. When the C/CDC ratio was 1 in the presence of 1 m M GCDC, only the rate of ureagenesis was diminished. When the C/CDC ratio was infinite, no hepatocellular injury was observed. GCDC and TCDC, together or separately, showed significant hepatocellular injury when the TBA concentration was 2 m M .     

Stentless bioprosthesis for aortic valve replacement

The stentless aortic bioprosthesis was reported to reduce left ventricular mass (LVM) in the early period after implantation and have better hemodynamic performance and a larger effective orifice area (EOA) than stented valves. However, its clinical advantage over the stented valve is still unclear. We have implanted stentless bioprostheses in 61 patients and had a low operative mortality rate (1.6%). LVM index, left ventricular end-diastolic volume (LVEDV) index, left ventricular end-systolic volume (LVESV) index, and peak pressure gradient (PG) were rapidly reduced after implantation. Ten-year-freedom from cardiac-related death, thromboemolism, and structural valve deterioration rates were 91.0%, 100%, and 95.0%, respectively. Furthermore, using MRI analysis, blood velocity through stentless valves was similar to that through native aortic valves in comparison with stented valves. In conclusion, the stentless valve enables more physiologic blood flow through the valve, and thus it may be useful in patients with small annuli or those who require better hemodynamic performance to enable physical activity.     

Disruption of gap junctions attenuates aminoglycoside-elicited renal tubular cell injury

BACKGROUND AND PURPOSE

Gap junctions play important roles in the regulation of cell phenotype and in determining cell survival after various insults. Here, we investigated the role of gap junctions in aminoglycoside-induced injury to renal tubular cells.

EXPERIMENTAL APPROACH

Two tubular epithelial cell lines NRK-E52 and LLC-PK1 were compared for gap junction protein expression and function by immunofluorescent staining, Western blot and dye transfer assay. Cell viability after exposure to aminoglycosides was evaluated by WST assay. Gap junctions were modulated by transfection of the gap junction protein, connexin 43 (Cx43), use of Cx43 siRNA and gap junction inhibitors.

KEY RESULTS

NRK-E52 cells expressed abundant Cx43 and were functionally coupled by gap junctional intercellular communication (GJIC). Exposure of NRK-E52 cells to aminoglycosides, G418 and hygromycin, increased Cx43 phosphorylation and GJIC. The aminoglycosides also decreased cell viability that was prevented by gap junction inhibitors and Cx43 siRNA. LLC-PK1 cells were gap junction-deficient and resistant to aminoglycoside-induced cytotoxicity. Over-expression of a wild-type Cx43 converted LLC-PK1 cells to a drug-sensitive phenotype. The gap junction inhibitor α-glycyrrhetinic acid (α-GA) activated Akt in NRK-E52 cells. Inhibition of the Akt pathway enhanced cell toxicity to G418 and abolished the protective effects of α-GA. In addition, gentamycin-elicited cytotoxicity in NRK-E52 cells was also significantly attenuated by α-GA.

CONCLUSION AND IMPLICATIONS

Gap junctions contributed to the cytotoxic effects of aminoglycosides. Modulation of gap junctions could be a promising approach for prevention and treatment of aminoglycoside-induced renal tubular cell injury.     

Cortical mechanisms of person representation: recognition of famous and personally familiar names

Personally familiar people are likely to be represented more richly in episodic, emotional, and behavioral contexts than famous people, who are usually represented predominantly in semantic context. To reveal cortical mechanisms supporting this differential person representation, we compared cortical activation during name recognition tasks between personally familiar and famous names, using an event-related functional magnetic resonance imaging (fMRI). Normal subjects performed familiar- or unfamiliar-name detection tasks during visual presentation of personally familiar (Personal), famous (Famous), and unfamiliar (Unfamiliar) names. The bilateral temporal poles and anterolateral temporal cortices, as well as the left temporoparietal junction, were activated in the contrasts Personal-Unfamiliar and Famous-Unfamiliar to a similar extent. The bilateral occipitotemporoparietal junctions, precuneus, and posterior cingulate cortex showed activation in the contrasts Personal-Unfamiliar and Personal-Famous. Together with previous findings, differential activation in the occipitotemporoparietal junction, precuneus, and posterior cingulate cortex between personally familiar and famous names is considered to reflect differential person representation. The similar extent of activation for personally familiar and famous names in the temporal pole and anterolateral temporal cortex is consistent with the associative role of the anterior temporal cortex in person identification, which has been conceptualized as a person identity node in many models of person identification. The left temporoparietal junction was considered to process familiar written names. The results illustrated the neural correlates of the person representation as a network of discrete regions in the bilateral posterior cortices, with the anterior temporal cortices having a unique associative role.     

Prognostic Value of BNP Reduction During Hospitalization in Patients With Acute Heart Failure

BackgroundPrognostication of patients discharged after acute heart failure (AHF) hospitalization remains challenging. Body weight (BW) reduction is often used as a surrogate marker of decongestion despite the paucity of evidence. We thought to test the hypothesis that B-type natriuretic peptide (BNP) reduction during hospitalization has independent prognostic value in AHF.Methods and ResultsWe studied the prognostic predictability of percentage BNP reduction achieved during hospitalization in patients from the REALITY-AHF study. Percentage BNP reduction was defined as (BNP on admission ? BNP at discharge) / BNP on admission × 100. The primary endpoint was 1-year all-cause death. In 1028 patients (age, 77 ± 13 years; 57% male; left ventricular ejection fraction, 47 ± 16%) with AHF, median BNP level at admission was 747 ng/L (interquartile range, 439–1367 ng/L) and median percentage BNP reduction was 62.5% (interquartile range, 36.5–78.5%). The smallest percentage BNP reduction quartile had more than 2-fold higher risk of all-cause death than the greatest quartile (23.0% vs 9.7%, P< .001). After adjusting for covariates including BNP at discharge, the percentage BNP reduction was significantly associated with all-cause death (hazard ratio 0.96, 95% confidence interval 0.93–0.99, P= .032), whereas percentage BW reduction was not. Percentage BNP reduction was more predictive in patients with heart failure with reduced ejection fraction than in those with preserved ejection fraction.ConclusionsThe prognostic value of percentage BNP reduction during hospitalization was superior to that of percentage BW reduction and was independent of other risk markers, including BNP at discharge.