Using phage to drive selections toward restoring antibiotic sensitivity in Pseudomonas aeruginosa via chromosomal deletions.

Phage therapy has re-emerged in modern medicine as a robust antimicrobial strategy in response to the increasing prevalence of antimicrobial-resistant bacteria. However, bacterial resistance to phages can also arise via a variety of molecular mechanisms. In fact, several clinical studies on phage therapy have reported the occurrence of phage-resistant variants, representing a significant concern for the successful development of phage-based therapies. In this context, the fitness trade-offs between phage and antibiotic resistance have revealed new avenues in the field of phage therapy as a countermeasure against phage resistance. This strategy forces to restore the antibiotic susceptibility of antimicrobial-resistant bacteria as compensation for the development of phage resistance. Here, we present the key achievements of these fitness trade-offs, notably focusing on the enhancement of antibiotic sensitivity through the induction of large chromosomal deletions by bacteriophage infection. We also describe the challenges of this strategy that need to be overcome to promote favorable therapeutic outcomes and discuss future directions. The insights gained from the trade-offs between phage and antibiotic sensitivity will help maximize the potential of phage therapy for the treatment of infectious diseases.

Association of prediabetes with impaired left atrial contractility in patients with never-treated hypertension.

AIM: Prediabetes defined by HbA1c 5.7-6.4 has been shown to be associated with left ventricular (LV) hypertrophy and diastolic dysfunction in hypertensive patients. We hypothesized HbA1c prediabetes may be related to the alterations of LA contractility or volume in nondiabetic hypertension. METHODS: Nondiabetic individuals on sinus rhythm were enrolled; 107 patients with never-treated hypertension, 134 patients with treated hypertension, and 71 normotensive subjects. Participants were classified as normal glucose tolerance (NGT, HbA1c<5.7), prediabetes (HbA1c 5.7-6.4) according to the ADA criteria. They underwent echocardiography to measure left atrial (LA) phasic volumes and functions, as well as mitral E/e' and mitral e'. RESULTS: In nondiabetic patients with never-treated hypertension, prediabetes saw lower LA total emptying fraction (53.7 ±â€¯8.2 vs. 48.3 ±â€¯9.9*) and mitral e' (7.38 ±â€¯2.18 vs. 6.17 ±â€¯1.50*) than NGT, implicating that the association of prediabetes with reduced LA contractility and LV stiffness. On the other hand, in nondiabetic patients with treated hypertension, prediabetes saw higher maximum LA volume/BSA (29.7 ±â€¯7.1 vs. 32.9 ±â€¯6.2* ml/mm2) and mitral E/e' (10.72 ±â€¯3.08 vs. 12.37 ±â€¯3.35*) than NGT, suggesting the relationship of prediabetes with increased LA preload. CONCLUSION: Prediabetes may be involved in the progression of LA structural and functional alterations in nondiabetic hypertensive patients.

Deep learning prediction of falls among nursing home residents with Alzheimer's disease.

AIM: This study aimed to use a convolutional neural network (CNN) to investigate the associations between the time of falling and multiple complicating factors, including age, dementia severity, lower extremity strength and physical function, among nursing home residents with Alzheimer's disease. METHODS: A total of 42 people with Alzheimer's disease were enrolled. We evaluated falling events from nursing home admission (baseline) to 300 days later. We assessed the knee extension strength and Functional Independence Measure locomotion item and carried out the Mini-Mental State Examination at baseline. To predict falling, participants were categorized into three classes: those who fell within the first 150 (or 300) days from baseline or those who did not experience a fall within the study period. For each class, 1000 bootstrap datasets were generated using 42 actual sample datasets, and were used to propose a CNN algorithm and cross-validate the algorithm. RESULTS: Eight (19.0%), 11 (26.2%) and 31 participants (73.8%) fell within 150 or 300 days after the baseline assessment or did not fall until 300 days or later, respectively. The highest accuracy rate of the CNN classification was 0.647 in the factor combination extracted from the Mini-Mental State Examination score, knee extension strength and Functional Independence Measure locomotion item score. CONCLUSIONS: A CNN based on multiple complicating factors could predict the time of falling in nursing home residents with Alzheimer's disease. Geriatr Gerontol Int 2020; ••: ••-••.

Inter-arm difference of systolic blood pressure measured by automated double-cuff device is associated with arterial stiffness in patients with hypertension.

PURPOSE: Inter-arm differences of SBP ≧5 mmHg have been associated with all-cause and cardiovascular mortalities in hypertensive subjects. Inter-arm differences of SBP appears to be mediated by arterial stiffness. We hypothesized inter-arm differences of SBP ≧5 mmHg may be related to higher pulse pressure/stroke volume index, a surrogate marker of arterial stiffness. MATERIALS AND METHODS: To obtain inter-arm differences of SBP (the absolute difference of right and left arm) and ankle-brachial index, bilateral blood pressures were measured simultaneously at the four limbs using an automated oscillometric device in patients with treated hypertension (n = 234) and in normotensive subjects (n = 40). Pulse pressure was calculated as SBP-DBP. Stroke volume was obtained by time-velocity integral method using echocardiography. Left ventricular mass and relative wall thickness were calculated by the conventional methods. RESULTS: All hypertensive patients were medically treated and had average blood pressure levels of 135/85 mmHg. Inter-arm differences of SBP ≧5 mmHg was detected in 26.5% of hypertensive patients. Hypertensive patients with inter-arm differences of SBP ≧5 mmHg had higher pulse pressure/stroke volume index, lower ankle-brachial index, higher BMI, and higher relative wall thickness, higher prevalence of female than those with inter-arm differences of SBP <5 mmHg. Multiple linear regression analysis confirmed inter-arm differences of SBP ≧5 mmHg was associated with higher pulse pressure/stroke volume index, higher relative wall thickness, and lower ankle-brachial index. CONCLUSION: Inter-arm difference of SBP measured by automated double-cuff device was related to large artery stiffness in patients with hypertension.

Association of tricuspid regurgitation within normal range on the development of left ventricular diastolic dysfunction in patients with uncomplicated hypertension.

AIM: Tricuspid regurgitation (TR) with the maximum velocity >2.8m/s has been newly integrated into the diagnostic criteria for left ventricular (LV) diastolic dysfunction. Although the maximum velocity of TR within the normal range (TR < 2.8m/s) is frequently detected in hypertensive patients and is associated with enlarged left atrial (LA) volumes, the influence of TR < 2.8m/s on LV diastolic dysfunction remains unknown in uncomplicated hypertension. METHODS: Echocardiography was performed to assess the mitral annular velocity (e'), E/e', LV mass, and LA phasic volumes and emptying fractions (total, passive, and active) in 100 patients with uncomplicated hypertension with TR within the normal range and in 77 of those without measurable TR. Patients were defined as having normal, inclusive, or dysfunction of LV diastolic function, according to how many parameters met the cut-off levels (maximum LA volume index >34ml/mm2, e'<7 cm/s, and E/e'>15). Pulmonary artery systolic pressure (PASP) was estimated by the formula; PASP =4 (maximum velocity of TR)2 + 5 mmHg. RESULTS: The maximum velocity of TR or PASP saw a positive correlation, and LA total or passive emptying fractions saw an inverse correlation with LV diastolic dysfunction in hypertensive patients with TR < 2.8. In contrast, pulse pressure and LV mass saw positive correlation in hypertensive patients without TR. A stepwise ordinal logistic regression analysis indicated that PASP and LA passive emptying fractions were associated with LV diastolic dysfunction in hypertensive patient with TR < 2.8m/s. CONCLUSION: The presence of TR may be related to the development of LV diastolic dysfunction in hypertensive patients with TR <2.8m/s.

Urinary type IV collagen is related to left ventricular diastolic function and brain natriuretic peptide in hypertensive patients with prediabetes.

AIM: Urinary type IV collagen is an early biomarker of diabetic nephropathy. Concomitant prediabetes (the early stage of diabetes) was associated with left ventricular (LV) diastolic dysfunction and increased brain natriuretic peptide (BNP) in hypertensive patients. We hypothesized that urinary type IV collagen may be related to these cardiac dysfunctions. METHODS: We studied hypertensive patients with early prediabetes (HbA1c <5.7% and fasting glucose >110, n=18), those with prediabetes (HbA1c 5.7-6.4, n=98), and those with diabetes (HbA1c>6.5 or on diabetes medications, n=92). The participants underwent echocardiography to assess left atrial volume/body surface area (BSA) and the ratio of early mitral flow velocity to mitral annular velocity (E/e'). Left ventricular diastolic dysfunction (LVDD) was defined if patients had E/e'≥15, or E/e'=9-14 accompanied by left atrial volume/BSA≥32ml/mm(2). Urinary samples were collected for type IV collagen and albumin, and blood samples were taken for BNP and HbA1c. RESULTS: Urinary type IV collagen and albumin increased in parallel with the deterioration of glycemic status. In hypertensive patients with prediabetes, subjects with LVDD had higher levels of BNP and urinary type IV collagen than those without LVDD. In contrast, in hypertensive patients with diabetes, subjects with LVDD had higher urinary albumin and BNP than those without LVDD. Urinary type IV collagen correlated positively with BNP in hypertensive patients with prediabetes, whereas it correlated with HbA1c in those with diabetes. CONCLUSIONS: In hypertensive patients with prediabetes, urinary type IV collagen was associated with LV diastolic dysfunction and BNP.

Utility of cystatin C as a marker for the severity of aortic regurgitation in hypertensive patients.

BACKGROUND: Cystatin C, a cathepsin inhibitor, is involved in the remodeling of human aortic valve and left ventricle (LV). OBJECTIVE: Cystatin C may be related to the severity of aortic regurgitation (AR). METHODS: We measured cystatin C and CRP in hypertensive patients with mild-to-moderate AR (n=120) and in those without AR (n=128). Echocardiography was performed to assess the vena contracta width (the narrowest region of regurgitant jet, VCW) as a marker of the severity of AR, relative wall thickness as a marker of LV concentric remodeling, and the ratio of early peak mitral flow to early diastolic mitral annular velocity (E/e') as an index of LV diastolic function. Glomerular filtration rate (GFR) was estimated using the MDRD methods. RESULTS: Cystatin C levels were greater in hypertensive patients with AR than in those without AR. A multiple linear regression analysis indicated cystatin C levels correlated with the VCW independent of GFR, body mass index, CRP, relative wall thickness, and E/e' in hypertensive patients with AR. CONCLUSIONS: Cystatin C was associated with the severity of regurgitation independent of renal function body composition chronic inflammation LV remodeling and diastolic function in hypertensive patients with mild-to-moderate AR.

A single intracoronary injection of midkine reduces ischemia/reperfusion injury in Swine hearts: a novel therapeutic approach for acute coronary syndrome.

Several growth factors are effective for salvaging myocardium and limiting infarct size in experimental studies with small animals. Their benefit in large animals and feasibility in clinical practice remains to be elucidated. We investigated the cardioprotective effect of midkine (MK) in swine subjected to ischemia/reperfusion (I/R). I/R was created by left anterior descending coronary artery occlusion for 45 min using a percutaneous over-the-wire balloon catheter. MK protein was injected as a bolus through the catheter at the initiation of reperfusion [MK-treated (MKT) group]. Saline was injected in controls (CONT). Infarct size/area at risk (24 h after I/R) in MKT was almost five times smaller than in CONT. Echocardiography in MKT revealed a significantly higher percent wall thickening of the interventricular septum, a higher left ventricular (LV) fractional shortening, and a lower E/e(') (ratio of transmitral to annular flow) compared with CONT. LV catheterization in MKT showed a lower LV end-diastolic pressure, and a higher dP/dt(max) compared with CONT. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling-positive myocytes and CD45-positive cell infiltration in the peri-infarct area were significantly less in MKT than in CONT. Here, we demonstrate that a single intracoronary injection of MK protein in swine hearts at the onset of reperfusion dramatically reduces infarct size and ameliorates systolic/diastolic LV function. This beneficial effect is associated with a reduction of apoptotic and inflammatory reactions. MK application during percutaneous coronary intervention may become a promising adjunctive therapy in acute coronary syndromes.

Rate-dependent shortening of action potential duration increases ventricular vulnerability in failing rabbit heart.

Congestive heart failure (CHF) predisposes to ventricular fibrillation (VF) in association with electrical remodeling of the ventricle. However, much remains unknown about the rate-dependent electrophysiological properties in a failing heart. Action potential properties in the left ventricular subepicardial muscles during dynamic pacing were examined with optical mapping in pacing-induced CHF (n=18) and control (n=17) rabbit hearts perfused in vitro. Action potential durations (APDs) in CHF were significantly longer than those observed for controls at basic cycle lengths (BCLs)>1,000 ms but significantly shorter at BCLs<400 ms. Spatial APD dispersions were significantly increased in CHF versus control (by 17-81%), and conduction velocity was significantly decreased in CHF (by 6-20%). In both groups, high-frequency stimulation (BCLs<150 ms) always caused spatial APD alternans; spatially concordant alternans and spatially discordant alternans (SDA) were induced at 60% and 40% in control, respectively, whereas 18% and 82% in CHF. SDA in CHF caused wavebreaks followed by reentrant excitations, giving rise to VF. Incidence of ventricular tachycardia/VFs elicited by high-frequency dynamic pacing (BCLs<150 ms) was significantly higher in CHF versus control (93% vs. 20%). In CHF, left ventricular subepicardial muscles show significant APD shortenings at short BCLs favoring reentry formations following wavebreaks in association with SDA. High-frequency excitation itself may increase the vulnerability to VF in CHF.

Acute amiodarone promotes drift and early termination of spiral wave re-entry.

Intravenous application of amiodarone is commonly used in the treatment of life-threatening arrhythmias, but the underlying mechanism is not fully understood. The purpose of the present study is to investigate the acute effects of amiodarone on spiral wave (SW) re-entry, the primary organization machinery of ventricular tachycardia/fibrillation (VT/VF), in comparison with lidocaine. A two-dimensional ventricular myocardial layer was obtained from 24 Langendorff-perfused rabbit hearts, and epicardial excitations were analyzed by high-resolution optical mapping. During basic stimulation, amiodarone (5 microM) caused prolongation of action potential duration (APD) by 5.6%-9.1%, whereas lidocaine (15 microM) caused APD shortening by 5.0%-6.4%. Amiodarone and lidocaine reduced conduction velocity similarly. Ventricular tachycardias induced by DC stimulation in the presence of amiodarone were of shorter duration (sustained-VTs >30 s/total VTs: 2/58, amiodarone vs 13/52, control), whereas those with lidocaine were of longer duration (22/73, lidocaine vs 14/58, control). Amiodarone caused prolongation of VT cycle length and destabilization of SW re-entry, which is characterized by marked prolongation of functional block lines, frequent wavefront-tail interactions near the rotation center, and considerable drift, leading to its early annihilation via collision with anatomical boundaries. Spiral wave re-entry in the presence of lidocaine was more stabilized than in control. In the anisotropic ventricular myocardium, amiodarone destabilizes SW re-entry facilitating its early termination. Lidocaine, in contrast, stabilizes SW re-entry resulting in its persistence.

Early termination of spiral wave reentry by combined blockade of Na+ and L-type Ca2+ currents in a perfused two-dimensional epicardial layer of rabbit ventricular myocardium.

BACKGROUND: Modification of spiral wave (SW) reentry by antiarrhythmic drugs is a central issue to be challenged for better understanding of their benefits and risks. OBJECTIVE: We investigated the effects of pilsicainide and/or verapamil, which block sodium and L-type calcium currents (I(Na) and I(Ca,L)), respectively, on SW reentry. METHODS: A two-dimensional epicardial ventricular muscle layer was created in rabbit hearts by cryoablation (n = 32), and action potential signals were analyzed by high-resolution optical mapping. RESULTS: During constant stimulation, pilsicainide (3-5 microM) caused a frequency-dependent decrease of conduction velocity (CV; by 20%-54% at 5 Hz) without affecting action potential duration (APD). Verapamil (3 microM) caused APD shortening (by 16% at 5 Hz) without affecting CV. Ventricular tachycardias (VTs) that were induced were more sustained in the presence of either pilsicainide or verapamil. The incidence of sustained VTs (>30 s)/all VTs per heart was 58% +/- 9% for 5 microM pilsicainide vs. 22% +/- 9% for controls and 62% +/- 10% for 3 microM verapamil vs. 22% +/- 8% for controls. The SWs with pilsicainide were characterized by slower rotation around longer functional block lines (FBLs), whereas those with verapamil were characterized by faster rotation around shorter FBLs. Combined application of 3 microM pilsicainide and 3 microM verapamil resulted in early termination of VTs (sustained VTs/all VTs per heart: 2% +/- 2% vs. 29% +/- 9% for controls); SWs showed extensive drift and decremental conduction, leading to their spontaneous annihilation. CONCLUSION: Blockade of either I(Na) or I(Ca,L) stabilizes SWs in a two-dimensional epicardial layer of rabbit ventricular myocardium to help their persistence, whereas blockade of both currents destabilizes SWs to facilitate their termination.

Moderate hypothermia increases the chance of spiral wave collision in favor of self-termination of ventricular tachycardia/fibrillation.

In cardiac arrest due to ventricular fibrillation (VF), moderate hypothermia (MH, 33 degrees C) has been shown to improve defibrillation success compared with normothermia (NR, 37 degrees C) and severe hypothermia (SH, 30 degrees C). The underlying mechanisms remain unclear. We hypothesized that MH might prevent reentrant excitations rotating around functional obstacles (rotors) that are responsible for the genesis of VF. In two-dimensional Langendorff-perfused rabbit hearts prepared by cryoablation (n = 13), action potential signals were recorded by a high-resolution optical mapping system. During basic stimulation (2.5-5.0 Hz), MH and SH caused significant prolongation of action potential duration and significant reduction of conduction velocity. Wavelength was unchanged at MH, whereas it was shortened significantly at SH at higher stimulation frequencies (4.0-5.0 Hz). The duration of direct current stimulation-induced ventricular tachycardia (VT)/VF was reduced dramatically at MH compared with NR and SH. The spiral wave (SW) excitations documented during VT at NR were by and large organized, whereas those during VT/VF at MH and SH were characterized by disorganization with frequent breakup. Phase maps during VT/VF at MH showed a higher incidence of SW collision (mutual annihilation or exit from the anatomical boundaries), which caused a temporal disappearance of phase singularity points (PS-0), compared with that at NR and SH. There was an inverse relation between PS-0 period in the observation area and VT/VF duration. MH data points were located in a longer PS-0 period and a shorter VT/VF duration zone compared with SH. MH causes a modification of SW dynamics, leading to an increase in the chance of SW collision in favor of self-termination of VT/VF.

Altered expression of connexin43 contributes to the arrhythmogenic substrate during the development of heart failure in cardiomyopathic hamster.

Heart failure is known to predispose to life-threatening ventricular tachyarrhythmias even before compromising the systemic circulation, but the underlying mechanism is not well understood. The aim of this study was to clarify the connexin43 (Cx43) gap junction remodeling and its potential role in the pathogenesis of arrhythmias during the development of heart failure. We investigated stage-dependent changes in Cx43 expression in UM-X7.1 cardiomyopathic hamster hearts and associated alterations in the electrophysiological properties using a high-resolution optical mapping system. UM-X7.1 hamsters developed left ventricular (LV) hypertrophy by ages 6 approximately 10 wk and showed a moderate reduction in LV contractility at age 20 wk. Appreciable interstitial fibrosis was recognized at these stages. LV mRNA and protein levels of Cx43 in UM-X7.1 were unaffected at age 10 wk but significantly reduced at 20 wk. The expression level of Ser255-phosphorylated Cx43 in UM-X7.1 at age 20 wk was significantly greater than that in control golden hamsters at the same age. In UM-X7.1 at age 10 wk, almost normal LV conduction was preserved, whereas the dispersion of action potential duration was significantly increased. UM-X7.1 at age 20 wk showed significant reduction of cardiac space constant, significant decrease in conduction velocity, marked distortion of activation fronts, and pronounced increase in action potential duration dispersion. Programmed stimulation resulted in sustained ventricular tachycardia or fibrillation in UM-X7.1. LV activation during polymorphic ventricular tachycardia was characterized by multiple phase singularities or wavebreaks. During the development of heart failure in the cardiomyopathic hamster, alterations of Cx43 expression and phosphorylation in concert with interstitial fibrosis may create serious arrhythmogenic substrate through an inhibition of cell-to-cell coupling.

Mechanisms of destabilization and early termination of spiral wave reentry in the ventricle by a class III antiarrhythmic agent, nifekalant.

Nifekalant (NF) is a novel class III antiarrhythmic agent that is effective in preventing life-threatening ventricular tachycardia/fibrillation (VT/VF). We investigated mechanisms of destabilization and early termination of spiral-type reentrant VT by NF in a two-dimensional subepicardial myocardial layer of Langendorff-perfused rabbit hearts (n = 21) using a high-resolution optical action potential mapping system. During basic stimulation, NF (0.1 microM) caused uniform prolongation of action potential duration (APD) without affecting conduction velocity and an increase of APD restitution slope. VTs induced by direct current stimulation in the presence of NF were of shorter duration (VTs > 30 s: 2/54 NF vs. 19/93 control). During VTs in control (with visible rotors), the wave front chased its own tail with a certain distance (repolarized zone), and they seldom met each other. The average number of phase singularity (PS) points was 1.31 +/- 0.14 per 665 ms (n = 7). In the presence of NF, the wave front frequently encountered its own tail, causing a transient breakup of the spiral wave or sudden movement of the rotation center (spatial jump of PS). The average number of PS was increased to 1.63 +/- 0.22 per 665 ms (n = 7, P < 0.05) after NF. The mode of spontaneous termination of rotors in control was in most cases (9/10, 90.0%) the result of mutual annihilation of counterrotating wave fronts. With NF, rotors frequently terminated by wave front collision with the atrioventricular groove (12/19, 63.2%) or by trapping the spiral tip in a refractory zone (7/19, 36.8%). Destabilization and early termination of spiral wave reentry induced by NF are the result of a limited proportion of excitable tissue after modulation of repolarization.

Optical imaging of spiral waves: pharmacological modification of spiral-type excitations in a 2-dimensional layer of ventricular myocardium.

Differential effects of sodium channel blockers, an I(Kr) blocker (nifekalant) and amiodarone on the spiral-type reentry, were investigated in rabbit hearts by using a high-resolution optical mapping system. Two-dimensional subepicardial layer of left ventricular myocardium with uniform anisotropy was prepared by endocardial cryoablation. During ventricular tachycardia (VT) elicited by cross-field stimulation, spiral-type excitations rotating around functional block lines (FBLs) were visualized. All the sodium channel blockers stabilized rotors; VT duration was prolonged in association with increases of FBLs and VT cycle length. The rotors in the presence of nifekalant were characterized by large meandering, long FBLs, and frequent front-tail interactions generating wave breaks. Amiodarone (acute application) increased FBLs and VT cycle length, but shortened the VT duration with minimal front-tail interaction. These results suggest that multifaceted drug action on both depolarization and repolarization may be required for the early termination of spiral-type reentry without causing breakup of rotors.