Search

Background A significant proportion of patients with acute myeloid leukemia (AML) will either be refractory to initial chemotherapy or will suffer refractory relapse. The role of allogeneic transplantation (SCT) in active disease is contentious. There is a growing body of literature that sequential chemotherapy, pioneered by the German FLAMSA regimen, followed by RIC SCT is a safe and efficacious modality in these patients, and there have been numerous modifications of this regimen, especially as amsacrineis not widely available. Fludarabine, cytarabineand and etoposide (VP16) (FLAV) have been reported as an effective salvage regimen. Here we report on single center outcomes of a variation of the FLAMSA regimen, substituting amsacrine for etoposide with mainly myeloablative conditioning. Methods Patients were offered this regimen if fit for allogenic HSCT and had AML which is refractory to two cycles of chemotherapy or refractory to one cycle and considered at high risk for complication with second cycles. Patients with MDS received this regimens if eligible for transplant with high or very high risk cytogenetics. All patients received cytoreductive chemotherapy consisted of fludarabine 30mg/m2/day x 4 days, Cytarabine 2g/m2/day x 4 days, etoposide 100mg/m2/day x 3days, commenced simultaneously. After 3 days of rest, conditioning chemotherapy consisted of fludarabine 30mg/m2 x 2 days and and IV busulfan 0.8mg/m2 q 6 hours; the number of busulfan doses varied between 8 - 12, depending on patient comorbidity. All patients received 2 doses of ATG at 2.5mg/m2/day on day -3 and -2. All patients received GCSF mobilized peripheral blood hematopoietic cells. Post-transplant GVHD prophylaxis consist of CsA and MMF. CsA was tapered from day+60 and stopped at day +90 in the absence of GVHD. MMF was discontinued between day +30 and day +40. Donor lymphocyte infusions were collected for planned prophylactic DLI. Results Twenty six patients received FLAV-SCT between March 2014 and July 2019. The median age was 38 (14-60); 16 (62%) female. Overall 12 (46%) pts had de novo AML, 10 (39%) pts had secondary or therapy related AML and 4 (15%) pts had MDS. Fourteen (54%) pts had adverse risk cytogenetics include 8 (31%) pts had complex or monosomal karyotype. Patients' characteristics are summarized in Table 1. All patients had active disease prior to FLAV-SCT. The median time for ANC and platelet engraftment was 14 (10 - 42) days and 17 (10 - 52) days respectively. Day 30 assessment shows CR in 16 (61%) pts and CR/CRi in 17 (65%) pts. Outcomes are summarized in Table 2. Three patients (12%) developed veno-occlusive disease. Acute GVHD grade II-IV and III-IV occurred in 9 (35%) pts and 2 (8%) pts respectively. Three (12%) patients developed chronic GVHD. Cumulative incidence of NRM at 100 days and 2 years was 8% and 12% respectively. The median OS for all pts was 5.2 months with 2 years rate of 32% (15 - 50). Among responders, the median OS and RFS were 19.2 months and 8.7 months, 2y-OS and RFS were 47% and 25%, respectively (Figure 1). Conclusion Our result demonstrates that transplant is an effective therapeutic modality in this very high risk refractory AML/MDS patients. Sequential chemotherapy (FLAV) followed by SCT with busulfan at myeloablative dose is tolerable with an acceptable toxicities and encouraging results. Figure 1 Figure 1. Disclosures Chaudhri: Novartis: Honoraria; Abbvie: Honoraria; Astra Zeneca: Honoraria. Alzahrani: King Faisal Specialist Hospital and Research Centre: Current Employment; Novartis: Consultancy, Honoraria; Bayer: Consultancy, Honoraria, Speakers Bureau; Sobi: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau.

Complement-mediated inflammation exacerbates the tissue injury of ischaemic necrosis in heart attacks and strokes, the most common causes of death in developed countries. Large infarct size increases immediate morbidity and mortality and, in survivors of the acute event, larger non-functional scars adversely affect long-term prognosis. There is thus an important unmet medical need for new cardioprotective and neuroprotective treatments. We have previously shown that human C-reactive protein (CRP), the classical acute-phase protein that binds to ligands exposed in damaged tissue and then activates complement1, increases myocardial and cerebral infarct size in rats subjected to coronary or cerebral artery ligation, respectively2, 3. Rat CRP does not activate rat complement, whereas human CRP activates both rat and human complement4. Administration of human CRP to rats is thus an excellent model for the actions of endogenous human CRP2, 3. Here we report the design, synthesis and efficacy of 1,6-bis(phosphocholine)-hexane as a specific small-molecule inhibitor of CRP. Five molecules of this palindromic compound are bound by two pentameric CRP molecules, crosslinking and occluding the ligand-binding B-face of CRP and blocking its functions. Administration of 1,6-bis(phosphocholine)-hexane to rats undergoing acute myocardial infarction abrogated the increase in infarct size and cardiac dysfunction produced by injection of human CRP. Therapeutic inhibition of CRP is thus a promising new approach to cardioprotection in acute myocardial infarction, and may also provide neuroprotection in stroke. Potential wider applications include other inflammatory, infective and tissue-damaging conditions characterized by increased CRP production, in which binding of CRP to exposed ligands in damaged cells may lead to complement-mediated exacerbation of tissue injury.

Background Mice are now widely used as models of cardiovascular disease. Their small size and fast heart rates are technically challenging to echocardiography. This study examined the influence of different scanning frequencies and ultrasonic contrast agent (UCA) on the accuracy and reproducibility of measurements of left ventricular (LV) structure and function. Methods Normal mouse hearts (C57BL6) were imaged at 3 different scanning frequencies before and after intravenous injection of the UCA, Optison. Coronary artery ligation mice and sham-operated controls were scanned at 10-22 MHz with and without UCA. Results Scanning frequency had no significant effect on intraobserver or interobserver variation of LV measurements in normal mice under baseline conditions. Use of UCA significantly reduced estimated ejection fraction at 10-22 MHz compared with baseline (baseline 50.8 ± 7.6% vs UCA 39.7 ± 7.6%; P = .03) and significantly increased values for LV cavity dimensions (eg, LV area diastole 20.74 ± 1.20 vs 23.23 ± 0.98 mm 2 ; P = .002). UCA significantly reduced intraobserver and interobserver variation in LV ejection fraction. Conclusions Scanning frequency had no significant effect on reproducibility of LV measurements in the mouse but UCA significantly reduced interobserver variation. Use of UCA could reduce the number of mice required in any given experiment to observe a statistically significant change in LV function.

Urotensin II (U-II) is a cyclic peptide, recently cloned in man and present in cardiac tissue and arteries. The effects of human U-II (hU-II) on coronary perfusion pressure (CPP) were investigated in isolated rat hearts perfused retrogradely via the aorta at constant flow. hU-II produced a concentration-dependent increase in CPP (pEC 50 8.6 ± 0.3, n =8), the maximum increase in CPP (12± 4 mmHg) was obtained at 10 −7 M hU-II. At higher concentrations of hU-II CPP fell back towards baseline. Endothelin-1 produced a maximum increase in CPP of 63±11 mmHg within the concentration-range studied. Addition of the NO synthase inhibitor L N G nitro-arginine methyl ester (10 −4 M) and the cyclooxygenase inhibitor, indomethacin (10 −5 M) to the perfusion solution had no effect on the pEC 50 value for hU-II, but significantly increased the maximum constriction (to 34 ± 7 mmHg, n = 8, p in vivo .

OBJECTIVE: Results from recent clinical trials of estrogen and progestogen therapy (EPT) suggest that some progestogens may interfere with the cardiovascular benefits of estrogen (E). The aim of this study was to investigate whether medroxyprogesterone acetate (MPA) modifies the protective effect of E in experimental ischemia-reperfusion (IR) injury in vivo and in vitro in the rat. DESIGN: Ovariectomized female Wistar rats (250-280 g, n = 61) received E, MPA, E and MPA, or placebo subcutaneously. Fourteen days later, hearts were isolated and perfused with Krebs Henseleit for in vitro experiments or left in situ for in vivo experiments. In both cases, the left coronary artery was occluded for 45 minutes, followed by 2 hours of reperfusion. RESULTS: In vivo E significantly reduced the necrotic zone of reperfused hearts (21.8% +/- 1.7% of area at risk) compared with placebo (42.8% +/- 4.8% area at risk; P < 0.05). This protection was reversed by co-administration of MPA with E (necrotic zone 38.2% +/- 6.1% area at risk). The influence of E on neutrophil infiltration was demonstrated by its ability to reduce myocardial myeloperoxidase activity (0.2 +/- 0.1 U/g tissue) relative to placebo (1.3 +/- 0.5 U/g tissue; P < 0.05). Myocardial myeloperoxidase activity was significantly increased to 1.1 +/- 0.3 U/g tissue in rats receiving E and MPA. However, MPA also reversed the protective effect of E in neutrophil-free buffer-perfused hearts, suggesting that additional mechanisms are involved. CONCLUSION: In this study, we showed that the administration of MPA can inhibit the effects of E that lead to protection of the myocardium from reperfusion injury and that this involves both neutrophil-dependent and neutrophil-independent mechanisms.

Angiogenesis restores blood flow to healing tissues, a process that is inhibited by high doses of glucocorticoids. However, the role of endogenous glucocorticoids and the potential for antiglucocorticoid therapy to enhance angiogenesis is unknown. Usingin vitroandin vivomodels of angiogenesis in mice, we examined effects of (i) endogenous glucocorticoids, (ii) blocking endogenous glucocorticoid action with the glucocorticoid receptor antagonist RU38486, and (iii) abolishing local regeneration of glucocorticoids by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1). Glucocorticoids, administered at physiological concentrations, inhibited angiogenesis in anin vitroaortic ring model andin vivoin polyurethane sponges implanted s.c. RU38486-enhanced angiogenesis in s.c. sponges, in healing surgical wounds, and in the myocardium of mice 7 days after myocardial infarction induced by coronary artery ligation. 11βHSD1 knockout mice showed enhanced angiogenesisin vitroandin vivowithin sponges, wounds, and infarcted myocardium. Endogenous glucocorticoids, including those generated locally by 11βHSD1, exert tonic inhibition of angiogenesis. Inhibition of 11βHSD1 in liver and adipose has been advocated to reduce cardiovascular risk in the metabolic syndrome: these data suggest that 11βHSD1 inhibition offers a previously uncharacterized therapeutic approach to improve healing of ischemic or injured tissue.

Mice are particularly popular as laboratory animals as they are relatively inexpensive to keep and are genetically very similar to humans. This together with the ease with which their genome can be manipulated has led to their increasing use as models of human disease processes. While the full range of imaging techniques can be utilised for imaging the mouse, the heart is particularly challenging as a result of rapid heart rate and required image resolution. Echocardiography is a powerful yet relatively inexpensive technique for cardiac imaging potentially able to address these issues. A real time high frequency linear array scanner coupled with a physiological signal capture package has been developed for the functional study of the mouse heart. This system overcomes the limitations of clinical cardiac ultrasound scanners previously employed for this purpose. A commercially available linear array scanner intended for muskuloskeletal imaging (Dynamic Imaging Ltd., Livingston, UK) has been modified to extend the frequency range up to 28 MHz and frame rate to 300 frames per second. The physiological signal capture system and a software analysis package enable the display of captured cine-loops and corresponding physiological signals. Over 100 mice have been scanned to date. Investigations underway include comparison of LV function in mice which had undergone coronary artery ligation under general anesthesia with sham operated animals acting as controls, the application and value of ultrasonic contrast agents and the dependence of functional assessment of the mouse heart on scanning frequency.

We employed Cre/loxP technology to generate mPDK1(-/-) mice, which lack PDK1 in cardiac muscle. Insulin did not activate PKB and S6K, nor did it stimulate 6-phosphofructo-2-kinase and production of fructose 2,6-bisphosphate, in the hearts of mPDK1(-/-) mice, consistent with PDK1 mediating these processes. All mPDK1(-/-) mice died suddenly between 5 and 11 weeks of age. The mPDK1(-/-) animals had thinner ventricular walls, enlarged atria and right ventricles. Moreover, mPDK1(-/-) muscle mass was markedly reduced due to a reduction in cardiomyocyte volume rather than cardiomyocyte cell number, and markers of heart failure were elevated. These results suggested mPDK1(-/-) mice died of heart failure, a conclusion supported by echocardiographic analysis. By employing a single-cell assay we found that cardiomyocytes from mPDK1(-/-) mice are markedly more sensitive to hypoxia. These results establish that the PDK1 signalling network plays an important role in regulating cardiac viability and preventing heart failure. They also suggest that a deficiency of the PDK1 pathway might contribute to development of cardiac disease in humans.

We have shown previously that a small bolus dose of endothelin-1, given intravenously before coronary occlusion, exerts a marked antiarrhythmic effect in anaesthetised rats. The aim of the current study was to determine whether or not this is due to a direct effect of endothelin-1 on the heart by assessing the antiarrhythmic effect of endothelin-1 against occlusion-induced arrhythmias in rat isolated hearts. Rat isolated hearts were perfused in Langendorff mode (constant flow) and subjected to coronary artery occlusion for 30 min. Coronary perfusion pressure and a surface electrocardiogram (ECG) were monitored throughout the experiment. In the first series of studies, the effects of three 5-min infusions of endothelin-1 (0.1–10 nM), given prior to coronary occlusion, were assessed. A second series of hearts was given a single bolus dose of endothelin-1 (10 pmol) 5 min prior to ischaemia. A third series of experiments was performed using a modified (low K+) Krebs Henseleit solution to increase the incidence of ischaemia-induced ventricular fibrillation (VF). In these hearts, endothelin-1 (0.1 or 2 pmol) was administered as a bolus injection 5 min before ischaemia. Infusion of endothelin-1 prior to ischaemia did not modify the incidence or severity of arrhythmias at any of the concentrations used. Bolus administration of endothelin-1 (10 pmol) in hearts perfused with Kreb's Henseleit solution containing normal K+ (4.4 mM) was found to cause a small rise in coronary perfusion pressure, with no preceding depressor response. Under these conditions, endothelin-1 exerted only a very moderate reduction in arrhythmias, by reducing the arrhythmia count in the 21–30-min post-occlusion period. Furthermore, in hearts perfused with low K+ solution, bolus injection of endothelin-1, in a dose that either had no effect on coronary perfusion pressure (0.1 pmol) or produced a significant vasodilator effect with no significant pressor effect (2 pmol), had no effect on ventricular fibrillation. Thus, in concentrations that are sufficient to exert effects on the coronary vasculature, endothelin-1 fails to modify arrhythmias in an isolated heart preparation. These results suggest that the antiarrhythmic effects of endothelin-1 previously observed in vivo are not due to a direct effect on either the myocardium or the coronary blood vessels.

The aim of this study was to investigate whether the endothelin-B- (ETB) receptor agonist sarafotoxin 6c (S6c) can protect against ischaemia-induced cardiac arrhythmias. Arrhythmias were induced by a 30 min period of coronary artery occlusion in pentobarbitone-anaesthetized male rats, or in Langendorff-perfused rat hearts. Rats or rat hearts were administered a bolus dose of vehicle or S6c (0.8 nmol/kg i.v. or 10(-8) M into the coronary circulation, respectively) 5 min before the onset of ischaemia. In vivo administration of S6c significantly reduced the incidence of ventricular fibrillation (VF) from 59% to 13% and the number of premature ventricular beats. This effect was associated with a transient fall in mean arterial blood pressure. In isolated hearts, S6c reduced significantly both the incidences of ventricular tachycardia (VT) and VF while having no statistically significant effect on coronary perfusion pressure. This is the first report to show that stimulation of ETB-receptors, with a bolus dose of S6c, has an antiarrhythmic effect on rat hearts both in vivo and in vitro, suggestive of a direct effect on the myocardium.

Objective: The aim of this study was to investigate the influence of endogenously released and exogenously applied endothelin-1 (ET-1) on ischaemia-induced arrhythmias. Methods: Ischaemia was induced in pentobarbitone-anaesthetised rats by ligation of a coronary artery for 30 min. To determine the role of endogenous ET-1 in ischaemic arrhythmias, either the ETA receptor antagonist BQ123 (50 μg/kg/min, i.v.; n =10) or the ETB receptor antagonist PD161721 (0.1 or 1 mg/kg i.v.; n =10 per group) was administered before the onset of ischaemia. To assess the influence of exogenous ET-1 on arrhythmias, ET-1 (1.6 nmol/kg i.v.) was administered 5 min before ischaemia in the absence ( n =12) or presence of BQ123 ( n =10) or PD161721 ( n =10). The total number of ventricular ectopic beats (VEB's) were counted and expressed as median (Q1−Q3) and the incidence of ventricular fibrillation (VF) and ventricular tachycardia (VT) in each group was determined. Mean arterial blood pressure (MABP) and heart rate (HR) were measured. Results: In control animals ( n =20), the incidence of VF was 65% and the total VEB count was 2775 (1870–4041). Both BQ123 and the higher dose of PD161721 reduced the VEB count to 654 (348–1489; P