Extracellular matrix promotes highly efficient cardiac differentiation of human pluripotent stem cells: the matrix sandwich method

RATIONALE

Cardiomyocytes (CMs) differentiated from human pluripotent stem cells (PSCs) are increasingly being used for cardiovascular research, including disease modeling, and hold promise for clinical applications. Current cardiac differentiation protocols exhibit variable success across different PSC lines and are primarily based on the application of growth factors. However, extracellular matrix is also fundamentally involved in cardiac development from the earliest morphogenetic events, such as gastrulation.

OBJECTIVE

We sought to develop a more effective protocol for cardiac differentiation of human PSCs by using extracellular matrix in combination with growth factors known to promote cardiogenesis.

METHODS AND RESULTS

PSCs were cultured as monolayers on Matrigel, an extracellular matrix preparation, and subsequently overlayed with Matrigel. The matrix sandwich promoted an epithelial-to-mesenchymal transition as in gastrulation with the generation of N-cadherin-positive mesenchymal cells. Combining the matrix sandwich with sequential application of growth factors (Activin A, bone morphogenetic protein 4, and basic fibroblast growth factor) generated CMs with high purity (up to 98%) and yield (up to 11 CMs/input PSC) from multiple PSC lines. The resulting CMs progressively matured over 30 days in culture based on myofilament expression pattern and mitotic activity. Action potentials typical of embryonic nodal, atrial, and ventricular CMs were observed, and monolayers of electrically coupled CMs modeled cardiac tissue and basic arrhythmia mechanisms.

CONCLUSIONS

Dynamic extracellular matrix application promoted epithelial-mesenchymal transition of human PSCs and complemented growth factor signaling to enable robust cardiac differentiation.

Spatial distribution of fibrosis governs fibrillation wave dynamics in the posterior left atrium during heart failure

Heart failure (HF) commonly results in atrial fibrillation (AF) and fibrosis, but how the distribution of fibrosis impacts AF dynamics has not been studied. HF was induced in sheep by ventricular tachypacing (220 bpm, 6 to 7 weeks). Optical mapping (Di-4-ANEPPS, 300 frames/sec) of the posterior left atrial (PLA) endocardium was performed during sustained AF (burst pacing) in Langendorff-perfused HF (n=7, 4 micromol/L acetylcholine; n=3, no acetylcholine) and control (n=6) hearts. PLA breakthroughs were the most frequent activation pattern in both groups (72.0+/-4.6 and 90.2+/-2.7%, HF and control, respectively). However, unlike control, HF breakthroughs preferentially occurred at the PLAs periphery near the pulmonary vein ostia, and their beat-to-beat variability was greater than control (1.93+/-0.14 versus 1.47+/-0.07 changes/[beats/sec], respectively, P<0.05). On histological analysis (picrosirius red), the area of diffuse fibrosis was larger in HF (23.4+/-0.4%) than control (14.1+/-0.6%; P<0.001, n=4). Also the number and size of fibrous patches were significantly larger and their location was more peripheral in HF than control. Computer simulations using 2-dimensional human atrial models with structural and ionic remodeling as in HF demonstrated that changes in AF activation frequency and dynamics were controlled by the interaction of electrical waves with clusters of fibrotic patches of various sizes and individual pulmonary vein ostia. During AF in failing hearts, heterogeneous spatial distribution of fibrosis at the PLA governs AF dynamics and fractionation.

Loss of H3K4 methylation destabilizes gene expression patterns and physiological functions in adult murine cardiomyocytes

Histone H3 lysine 4 (H3K4me) methyltransferases and their cofactors are essential for embryonic development and the establishment of gene expression patterns in a cell-specific and heritable manner. However, the importance of such epigenetic marks in maintaining gene expression in adults and in initiating human disease is unclear. Here, we addressed this question using a mouse model in which we could inducibly ablate PAX interacting (with transcription-activation domain) protein 1 (PTIP), a key component of the H3K4me complex, in cardiac cells. Reducing H3K4me3 marks in differentiated cardiomyocytes was sufficient to alter gene expression profiles. One gene regulated by H3K4me3 was Kv channel-interacting protein 2 (Kcnip2), which regulates a cardiac repolarization current that is downregulated in heart failure and functions in arrhythmogenesis. This regulation led to a decreased sodium current and action potential upstroke velocity and significantly prolonged action potential duration (APD). The prolonged APD augmented intracellular calcium and in vivo systolic heart function. Treatment with isoproterenol and caffeine in this mouse model resulted in the generation of premature ventricular beats, a harbinger of lethal ventricular arrhythmias. These results suggest that the maintenance of H3K4me3 marks is necessary for the stability of a transcriptional program in differentiated cells and point to an essential function for H3K4me3 epigenetic marks in cellular homeostasis.

Nongenomic thyroid hormone signaling occurs through a plasma membrane-localized receptor

Thyroid hormone (TH) is essential for vertebrate development and the homeostasis of most adult tissues, including bone. TH stimulates target gene expression through the nuclear thyroid receptors TRα and TRβ; however, TH also has rapid, transcription-independent (nongenomic) effects. We found a previously uncharacterized plasma membrane-bound receptor that was necessary and sufficient for nongenomic TH signaling in several cell types. We determined that this receptor is generated by translation initiation from an internal methionine of TRα, which produces a transcriptionally incompetent protein that is palmitoylated and associates with caveolin-containing plasma membrane domains. TH signaling through this receptor stimulated a pro-proliferative and pro-survival program by increasing the intracellular concentrations of calcium, nitric oxide (NO), and cyclic guanosine monophosphate (cGMP), which led to the sequential activation of protein kinase G II (PKGII), the tyrosine kinase Src, and extracellular signal-regulated kinase (ERK) and Akt signaling. Hypothyroid mice exhibited a cGMP-deficient state with impaired bone formation and increased apoptosis of osteocytes, which was rescued by a direct stimulator of guanylate cyclase. Our results link nongenomic TH signaling to a previously uncharacterized membrane-bound receptor, and identify NO synthase, guanylate cyclase, and PKGII as TH effectors that activate kinase cascades to regulate cell survival and proliferation.

Atrial septopulmonary bundle of the posterior left atrium provides a substrate for atrial fibrillation initiation in a model of vagally mediated pulmonary vein tachycardia of the structurally normal heart

BACKGROUND

The posterior left atrium (PLA) and pulmonary veins (PVs) have been shown to be critical for atrial fibrillation (AF) initiation. However, the detailed mechanisms of reentry and AF initiation by PV impulses are poorly understood. We hypothesized that PV impulses trigger reentry and AF by undergoing wavebreaks as a result of sink-to-source mismatch at specific PV-PLA transitions along the septopulmonary bundle, where there are changes in thickness and fiber direction.

METHODS AND RESULTS

In 7 Langendorff-perfused sheep hearts AF was initiated by a burst of 6 pulses (CL 80 to 150ms) delivered to the left inferior or right superior PV ostium 100 to 150 ms after the sinus impulse in the presence of 0.5 micromol/L acetylcholine. The exposed septal-PLA endocardial area was mapped with high spatio-temporal resolution (DI-4-ANEPPS, 1000-fr/s) during AF initiation. Isochronal maps for each paced beat preceding AF onset were constructed to localize areas of conduction delay and block. Phase movies allowed the determination of the wavebreak sites at the onset of AF. Thereafter, the PLA myocardial wall thickness was quantified by echocardiography, and the fiber direction in the optical field of view was determined after peeling off the endocardium. Finally, isochrone, phase and conduction velocity maps were superimposed on the corresponding anatomic pictures for each of the 28 episodes of AF initiation. The longest delays of the paced PV impulses, as well as the first wavebreak, occurred at those boundaries along the septopulmonary bundle that showed sharp changes in fiber direction and the largest and most abrupt increase in myocardial thickness.

CONCLUSION

Waves propagating from the PVs into the PLA originating from a simulated PV tachycardia triggered reentry and vagally mediated AF by breaking at boundaries along the septopulmonary bundle where abrupt changes in thickness and fiber direction resulted in sink-to-source mismatch and low safety for propagation.

In vitro anti-HIV activity of five selected South African medicinal plant extracts

AIM OF THE STUDY

Five South African medicinal plants, Bulbine alooides (L.) Willd. (Asphodelaceae), Crinummacowani Baker (Amaryllidaceae), Hypoxis sobolifera var. sobolifera (Jacq.) Nel (Hypoxidaceae), Leonotisleonurus (L.) R.Br. (Lamiaceae) and Tulbaghiaviolacea Harv (Liliaceae) used for the treatment of various ailments, including infectious diseases, were screened for activity against human immunodeficiency virus (HIV).

MATERIALS AND METHODS

Aqueous and ethanol extracts were tested for inhibitory activity in HIV-1 infected CEM.NK(R)-CCR5 cells, and against HIV-1 reverse transcriptase (RT) and HIV-1 protease (PR).

RESULTS

In CEM.NK(R)-CCR5 cells, ethanol extracts of Leonotisleonurus inhibited HIV-1 significantly (33% reduction in HIV-1 p24, P<0.05). HIV-1 RT inhibition (> or =50%) was shown for extracts of Bulbine alooides (aqueous and ethanol), Hypoxis sobolifera (aqueous and ethanol) and Leonotisleonurus (aqueous), but inhibitory activity was lost upon dereplication for removal of non-specific tannins/polysaccharides. HIV-1 PR inhibition was observed for extracts of Hypoxis sobolifera (aqueous), Bulbine alooides (aqueous and ethanol) and Leonotisleonurus (ethanol). Only ethanolic extracts of Bulbine alooides and Leonotisleonurus retained HIV-1 PR inhibition after dereplication with IC50 of 94 microg/ml and 120 microg/ml, respectively.

CONCLUSION

The dereplicated ethanolic extracts of Leonotisleonurus and Bulbine alooides showed the greatest anti-HIV potential in this study through inhibition of HIV-1 PR.

The effects of the ketone body β-hydroxybutyrate on isolated rat ventricular myocyte excitation-contraction coupling

β-hydroxybutyrate is the primary ketone body produced by the body during ketosis and is used to meet its metabolic demands. The healthy adult heart derives most of its energy from fatty acid oxidation. However, in certain diseases, the heart alters its substrate preference and increases its ketone body metabolism. Little is known about the effects of βOHB on ventricular myocyte excitation-contraction coupling. Therefore, we examined the effects of ketone body metabolism on single cell excitation-contraction coupling during normoxic and hypoxic conditions. Myocytes were isolated from adult rats, cultured for 18 h in RPMI 1640, RPMI 1640 no glucose, and M199, HEPES with/without various amount of βOHB added. To simulate hypoxia, myocytes were incubated at 1%O₂, 5% CO₂ for 1 h followed by incubation at atmospheric oxygen (21%O₂,5% CO₂) for 30 min before recordings. Recordings were obtained using an IonOptix system at 36±1ᵒ C. Myocytes were paced at 0.5, 1, 2, 3, and 4 Hz. We found that exposure to βOHB had no effect on excitation-contraction coupling. However, culturing cells with βOHB results in a significant increase in both contraction and calcium in RPMI 1640 media. Dose response experiments demonstrated 0.5 mM βOHB is enough to increase myocyte contraction in the absence of glucose. However, βOHB has no measurable effects on myocytes cultured in a nutrient rich media, M199, HEPES. Therefore, βOHB improves single cell excitation-contraction coupling, is protective against hypoxia, and may be a beneficial adaptation for the heart during periods of nutrient scarcity and or metabolic dysregulation.

Endoscopic fluorescence mapping of the left atrium: a novel experimental approach for high resolution endocardial mapping in the intact heart

BACKGROUND

Despite the availability of several mapping technologies for investigating the electrophysiologic mechanisms of atrial fibrillation (AF), an experimental tool enabling high-resolution mapping of electrical impulses on the endocardial surface of the intact left atrium is lacking.

OBJECTIVE

The purpose of this report is to present a new optical mapping approach implementing a steerable cardio-endoscope in isolated hearts.

METHODS

The system consists of a direct or side-view endoscope coupled to a 532-nm excitation laser for illumination and a CCD camera for imaging of potentiometric dye fluorescence (di-4-ANEPPS, 80 x 80 pixels, 200-800 frames/s). The cardio-endoscope was aimed successively at diverse posterior left atrial locations to obtain high-resolution movies of electrical wave propagation and detailed endocardial anatomic features in the presence and absence of atrial stretch.

RESULTS

We present several examples of high-resolution endoscopic posterior left atrial recordings of wave propagation patterns during both sinus rhythm and AF with signal-to-noise ratio similar to conventional optical mapping systems. We demonstrate the endoscope's ability to visualize highly organized AF sources (rotors) at specific locations on the posterior left atrium and posterior left atrium-pulmonary vein junctions. We present video images of waves emanating from such sources as they propagate into pectinate muscles in the left atrial appendage. In particular, we demonstrate this approach is ideally suited for studying the effects of atrial stretch on AF dynamics.

CONCLUSION

In isolated hearts, cardio-endoscopic optical mapping of electrical activity should enable comprehensive evaluation of AF activity in the posterior left atrium, the role of local anatomy on AF dynamics, and the efficacy of pharmacologic and ablative interventions.

Left atrial coronary perfusion territories in isolated sheep hearts: implications for atrial fibrillation maintenance

BACKGROUND

The role of coronary perfusion in the maintenance of atrial fibrillation (AF) electrical sources that anchor to the posterior (wall of the) left atrium (PLA) has been incompletely investigated. We hypothesized that the PLA-pulmonary vein region is perfused by branches originating from both the right and left coronary arteries.

OBJECTIVE

The purpose of this study was to evaluate whether branches originating from the right and left coronary arteries could serve as conduits to chemically ablate restricted PLA regions.

METHODS

In Langendorff-perfused sheep hearts, the right anterior and left anterior atrial arteries (RAAA and LAAA) and the branches of the left circumflex artery (LCX) were identified as main coronary artery branches perfusing the atria. During sustained AF, 20-mL boluses of cold Tyrode's solution (4°C) was injected into each artery to determine changes in dominant frequency. The injection that yielded the largest dominant frequency decrease indicated the coronary branch to be subsequently perfused with ethanol. Ethanol was selectively injected into the LAAA (n = 4), LCX (n = 4), or RAAA (n = 1).

RESULTS

Six of nine AF cases rapidly terminated upon ethanol perfusion. In those hearts and in eight additional preparations (n = 17), Congo red and Evans blue was subsequently perfused into the remaining atrial branches. The perfusion territories were classified as triple-vessel PLA perfusion (n = 4), LAAA-dominant PLA perfusion (n = 5), balanced double-vessel PLA perfusion (n = 5), and LCX or RAAA dominant (n = 3).

CONCLUSION

PLA coronary perfusion relies on a variable contribution of right and left coronary branches. Regional irrigation of ethanol in well-delineated PLA perfusion territories enabled ablation of high-frequency sites during AF.

Success of bone marrow transplantation in congenital Diamond-Blackfan anaemia: a case report

A 6-yr-old girl with congenital corticosteroid-resistant pure red cell aplasia was treated with bone marrow transplant from her HLA-identical, MLC-unreactive sister in November 1984 following conditioning with busulfan and cyclophosphamide. Full engraftment was obtained and the patient at 21 months post-transplant is in excellent clinical condition maintaining normal red cell counts. We conclude that BMT should be considered as a therapy for at least the most severe cases of Diamond-Blackfan anaemia resistant to corticosteroids. Successful outcome of this therapy provides an argument for the stem cell origin of this disorder.

Inhibition of TGFβ1 accelerates regeneration of fibrotic rat liver elicited by a novel two-staged hepatectomy

Aims: Emerging evidence is demonstrating that rapid regeneration of remnant liver elicited by associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) may be attenuated in fibrotic livers. However, the molecular mechanisms responsible for this process are largely unknown. It is widely acknowledged that the TGFβ1 signaling axis plays a major role in liver fibrosis. Therefore, the aims of this study were to elucidate the underlying mechanism of liver regeneration during ALPPS with or without fibrosis, specifically focusing on TGFβ1 signaling. Approach: ALPPS was performed in rat models with N-diethylnitrosamine-induced liver fibrosis and no fibrosis. Functional liver remnant regeneration and expression of TGFβ1 were analyzed during the ALPPS procedures. Adeno-associated virus-shTGFβ1 and the small molecule inhibitor LY2157299 (galunisertib) were used separately or in combination to inhibit TGFβ1 signaling in fibrotic rats. Results: Liver regeneration following ALPPS was lower in fibrotic rats than non-fibrotic rats. TGFβ1 was a key mediator of postoperative regeneration in fibrotic liver. Interestingly, AAV-shTGFβ1 accelerated the regeneration of fibrotic functional liver remnant and improved fibrosis, while LY2157299 only enhanced liver regeneration. Moreover, combination treatment elicited a stronger effect. Conclusions: Inhibition of TGFβ1 accelerated regeneration of fibrotic liver, ameliorated liver fibrosis, and improved liver function following ALPPS. Therefore, TGFβ1 is a promising therapeutic target in ALPPS to improve fibrotic liver reserve function and prognosis.

Cardiomyocyte Expression of ZO-1 Is Essential for Normal Atrioventricular Conduction but Does Not Alter Ventricular Function

RATIONALE

ZO-1 (Zonula occludens-1), a plasma membrane-associated scaffolding protein regulates signal transduction, transcription, and cellular communication. Global deletion of ZO-1 in the mouse is lethal by embryonic day 11.5. The function of ZO-1 in cardiac myocytes (CM) is largely unknown.

OBJECTIVE

To determine the function of CM ZO-1 in the intact heart, given its binding to other CM proteins that have been shown instrumental in normal cardiac conduction and function.

METHODS AND RESULTS

We generated ZO-1 CM-specific knockout (KO) mice using α-Myosin Heavy Chain-nuclear Cre (ZO-1cKO) and investigated physiological and electrophysiological function by echocardiography, surface ECG and conscious telemetry, intracardiac electrograms and pacing, and optical mapping studies. ZO-1cKO mice were viable, had normal Mendelian ratios, and had a normal lifespan. Ventricular morphometry and function were not significantly different between the ZO-1cKO versus control (CTL) mice, basally in young or aged mice, or even when hearts were subjected to hemodynamic loading. Atrial mass was increased in ZO-1cKO. Electrophysiological and optical mapping studies indicated high-grade atrioventricular (A-V) block in ZO-1cKO comparing to CTL hearts. While ZO-1-associated proteins such as vinculin, connexin 43, N-cadherin, and α-catenin showed no significant change with the loss of ZO-1, Connexin-45 and Coxsackie-adenovirus (CAR) proteins were reduced in atria of ZO-1cKO. Further, with loss of ZO-1, ZO-2 protein was increased significantly in ventricular CM in a presumed compensatory manner but was still not detected in the AV nodal myocytes. Importantly, the expression of the sodium channel protein NaV1.5 was altered in AV nodal cells of the ZO-1cKO versus CTL.

CONCLUSIONS

ZO-1 protein has a unique physiological role in cardiac nodal tissue. This is in alignment with its known interaction with CAR and Cx45, and a new function in regulating the expression of NaV1.5 in AV node. Uniquely, ZO-1 is dispensable for function of the working myocardium.

Chitin: an immunological adjuvant and a polyclonal B-lymphocyte activator

Chitin, a linear beta 1-4 linked poly-N-acetylglucosamine, enhanced the in vivo immune response of normal mice to sheep red blood cells, but not that of mice with thymic aplasia (nude mice). The compound is mitogenic for murine B lymphocytes but not for thymocytes or splenic T lymphocytes. Similarly to well-known polyclonal B-lymphocyte activators; e.g. lipopolysaccharide, chitin induces differentiation of B lymphocytes into antibody-forming cells in vitro.

Altered myocyte contractility and calcium homeostasis in alpha-myosin heavy chain point mutations linked to familial dilated cardiomyopathy

Mutations in the human cardiac motor protein beta-myosin heavy chain (βMHC) have been long recognized as a cause of familial hypertrophic cardiomyopathy. Recently, mutations (P830L and A1004S) in the less abundant but faster isoform alpha-myosin heavy chain (αMHC) have been linked to dilated cardiomyopathy (DCM). In this study, we sought to determine the cellular contractile phenotype associated with these point mutations. Ventricular myocytes were isolated from 2 month male Sprague Dawley rats. Cells were cultured in M199 media and infected with recombinant adenovirus containing the P830L or the A1004S mutant human αMHC at a MOI of 500 for 18 h. Uninfected cells (UI), human βMHC (MOI 500, 18 h), and human αMHC (MOI 500, 18 h) were used as controls. Cells were loaded with fura-2 (1 μM, 15 min) after 48 h. Sarcomere shortening and calcium transients were recorded in CO₂ buffered M199 media (36°±1 C) with and without 10 nM isoproterenol (Iso). The A1004S mutation resulted in decreased peak sarcomere shortening while P830L demonstrated near normal shortening kinetics at baseline. In the presence of Iso, the A1004S sarcomere shortening was identical to the βMHC shortening while the P830L was identical to the αMHC control. All experimental groups had identical calcium transients. Despite a shared association with DCM, the P830L and A1004S αMHC mutations alter myocyte contractility in completely different ways while at the same preserving peak intracellular calcium.

Reversible cerebral hyperperfusion syndrome after stenting of the carotid artery—Two case reports

Hyperperfusion syndrome can complicate carotid revascularization, be it endarterectomy or carotid artery stenting (CAS). Although extensive effort has been devoted to reducing the incidence of ischemic stroke complicating CAS, little is known about the incidence, etiology, and prevention strategies for hyperperfusion following CAS. We report two cases (female patients 72 and 81 years) presenting severe internal carotid stenosis (> 90%), who underwent presurgical and therapeutic intervention with CAS. Both patients developed hyperperfusion symptoms at 2 hours and at 30 minutes, respectively, following stenting, in both cases unilateral hyperperfusion was CCT confirmed. Case 1 was presenting with acute edema of the right hemisphere, case 2 with distended focal edema (left fronto-temporoparietally). Hyperperfusion syndrome and neurological symptoms retroceded in both cases (conservative therapy) and both patients returned to full activity (case 2 within 48 hours).

Revision of 116 orthognathic surgery patients operated on with the high-oblique sagittal osteotomy (HOSO): a retrospective case series (PROCESS-compliant article)

BACKGROUND

The high-oblique sagittal osteotomy (HOSO) is an alternative to a bilateral sagittal split osteotomy (BSSO). Due to its novelty, there are no long-term studies which have focused on describing the incidence and type of complications encountered in the post-operative follow-up. The aim of this retrospective study is to analyze patients operated on with this surgical technique and the post-operative complications encountered.

PATIENT AND METHODS

The electronic medical records of all patients treated with orthognathic surgery at the Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Frankfurt, Goethe University, Frankfurt, Germany, between the years 2009 and 2016 were retrospectively reviewed.

RESULTS

A total of 116 patients fulfilled the inclusion criteria. The cases operated on with the standard osteosynthesis (X, Y, and straight) showed a complication rate of 36.37% (n = 4/11). The cases operated on with the HOSO-dedicated plates (HOSO-DP) showed, in total, a complication rate of 6.67% (n = 7/105). The most common post-operative complication resulting from both fixation methods was a reduction in mouth opening and TMJ pain for 4.3%. During the first years of performing the surgery (2009-211), a variety of standard plates had material failure causing non-union or pseudarthrosis. No cases of material failure were observed in the cases operated on with the HOSO-DP. The statistical results showed a highly significant dependence of a reduction in OP-time over the years, when the HOSO was performed without additional procedures (R² > 0.83, P < 0.0015).

CONCLUSION

The rate of complications in the HOSO were shown to be comparable to the rate of complications from the BSSO reported in the literature. Moreover, the use of the ramus dedicated plate appears to provide enough stability to the bone segments, making the surgery safer.

CLINICAL RELEVANCE

The HOSO needs to be considered by surgeons as an alternative to BSSO. Once the use of the HOSO-DP was established, the rate of complications and the operation time reduced considerably.

Lack of relationship between the HLA system and subacute sclerosing panencephalitis

Thirty-six HLA - A, B and C antigens were typed in 35 SSPE patients. No difference in the frequency of any of the antigens studied was noted between SSPE and age-, sex- and race-matched controls. Nor was there any difference when they were compared with the adult control group.

[Treatment of myocardial infarction by primary PTCA within 12 to 24 hours after onset of pain]

BACKGROUND AND OBJECTIVE

The time elapsed until effective infarct vessel perfusion has been identified as an essential determinant of survival after acute myocardial infarction (MI). Significant mortality rate reduction has not been demonstrated for patients who received thrombolytic treatment more than 12 to 24 hours after MI. For this reason such patients have so far largely been denied reperfusion treatment and have thus been excluded from any potential benefit of an reopened infarct vessel. It was the aim of this study to assess the applicability and safety of achieving reperfusion by percutaneous transluminal coronary angioplasty (PTCA) without prior thrombolysis (primary PTCA) within 12 (> 12) to 24 (< or = 24) hours after onset of pain, taking into account early and late results in selected consecutive patients.

PATIENTS AND METHODS

The data were analysed retrospectively of 35 patients (29 men, 6 women; mean age 60 [49-78] years) who had been admitted and treated by primary PTCA for MI more than 12-24 hours after onset of pain, with persisting ECG changes and (or) continuing chest pain. Reperfusion rates, acute haemodynamic parameters, acute cardiac and noncardiac complications, 30-day mortality rate, 3-month angiographic results and late mortality rate were obtained after an average of 23 (4-36) months.

RESULTS

Complete infarct vessel reperfusion was achieved in 30 patients (85.7%), the infarct vessel remaining occluded in five. The early measurement of mean left ventricular ejection fraction was 53% (8-76%). A small, conservatively managed pericardial effusion occurred in one patient due to coronary artery penetration. Three patients who were in cardiogenic shock on admission died (8.6% 30-day mortality rate). Nine cases of restenosis and two of re-occlusion of the infarct vessel were documented in 24 patients who were investigated invasively 3 months after the primary PTCA. One patient had sustained a nonfatal MI. During the follow-up period one patient died of a noncardiac cause.

INTERPRETATION

In this selected group of patients who received treatment more than 12 to 24 hours after MI primary PTCA achieved a high rate of reperfusion, while early and late complications were rare. Using individualized criteria of patient selection, primary PTCA can accomplish recanalization. The question of prognostic advantage can only be answered by results in a larger and randomized cohort of patients.

Interaction between Entamoeba histolytica and the immune system. I. Mitogenicity of Entamoeba histolytica extracts for human peripheral T lymphocytes

The effect of Entamoeba histolytica extracts (E.h.e.) on proliferation in vitro of human peripheral blood lymphocytes, cord blood lymphocytes, and lymphocytes enriched for T cells or non-T cells was investigated. As tested by 3H-thymidine uptake and by morphologic criteria, E.h.e. stimulate T lymphocyte proliferation. Non-T lymphocytes do not respond to E.h.e. The response of lymphocytes to E.h.e. differed from their response to Con A in several respects, indicating either that E.h.e. and Con A act on different subsets of T cells or that E.h.e. act by different mechanism on the Con A reactive cells.

Direct in vitro evidence for different susceptibilities to 4-hydroperoxycyclophosphamide of antigen-primed T cells regulating humoral and cell-mediated immune responses to sheep erythrocytes: a possible explanation for the inverse action of cyclophosphamide on humoral and cell-mediated immune responses

Suppressor T cells of humoral immune responses, effector T cells mediating DTH, suppressor T cells of DTH, and helper T cells of humoral immune responses, all with specificity to SRBC, were produced in mice. The biologic activity was tested in adoptive transfer experiments. In vitro treatment with different doses of 4-hydroperoxycyclophosphamide (4-HPCy) yielded the result that the various activities tested were not uniformly sensitive to the action of this drug: Suppressor T cells of humoral immune responses and effector T cells mediating DTH were resistant to doses of 4-HPCy that eliminated the activities of suppressor T cells of DTH and helper cells of the humoral immune response. These findings help to explain the various effects cyclophosphamide has on the in vivo immune response and may help to form a basis for the rational manipulation of the immune response by drugs that selectively affect different subgroups of immune cells.

Interaction between Entamoeba histolytica and the immune system. I. Mitogenicity of Entamoeba histolytica extracts for human peripheral T lymphocytes

The effect of Entamoeba histolytica extracts (E.h.e.) on proliferation in vitro of human peripheral blood lymphocytes, cord blood lymphocytes, and lymphocytes enriched for T cells or non-T cells was investigated. As tested by 3H-thymidine uptake and by morphologic criteria, E.h.e. stimulate T lymphocyte proliferation. Non-T lymphocytes do not respond to E.h.e. The response of lymphocytes to E.h.e. differed from their response to Con A in several respects, indicating either that E.h.e. and Con A act on different subsets of T cells or that E.h.e. act by different mechanism on the Con A reactive cells.

Abstract 192: Sex Dependent Differences in Cardiac Myocyte Excitation-Contraction Coupling After Chronic Stimulation of the Delta or Kappa Opioid Receptors During Normoxic and Hypoxic Conditions

Introduction: In 2016 the US government declared opioid misuse a public emergency. While most opioid related deaths can be attributed to overdose, recent data suggest a link between opioid use and cardiovascular disease. Further, epidemiological data suggest it may be sex dependent, with females (♀) being at a somewhat higher risk than males (♂). This is paradoxical because until menopause, ♀ have a lower risk of heart disease when compared to ♂. Healthy adult hearts express the δ and κ ORs, but not the μOR. Therefore, the overall goals of this study using a reductionist model were to: 1). To determine if there are sex specific differences in cardiac myocyte excitation-contraction coupling between ♂ and ♀ myocytes exposed to δ or κ OR agonists during normoxia/hypoxia. 2). Examine if 17β-Estradiol enhances or augments the effects of δ or κ OR stimulation.

Methods: Myocytes were isolated from adult ♂ and ♀ Sprague-Dawley rats and cultured overnight in M199 HEPES media, or M199 HEPES media containing either 1 μM DADLE (δ agonist), 20 μM U50-488 (κ agonist), 100 nm 17β-Estradiol, 1μM DADLE + 100 nm 17β-Estradiol, or 20 μM U50-488 + 100 nm 17β-Estradiol. To simulate an infarct, a subset of the myocytes was incubated at 1%O 2 , 5% CO 2 for 4 hours + 10 nM isoproterenol followed by 60 min normoxia (21%O 2 , 5% CO 2 ) before recordings. Excitation-Contraction was measured using an IonOptix rig (IonOptix LLC, Milton MA) at 36±1° at 1 Hz pacing.

Results: During normoxia, ♂ myocytes compared to ♀ myocytes had an increased peak contraction and peak Ca 2+ transient. The addition of 100 nM 17β-Estradiol did not affect peak contraction in either sex but decreased the Ca 2+ transient in ♂ myocytes while increasing it in ♀ myocytes. DADLE and U50-488 had no effect on ♀ myocyte contractility but decreased ♂ myocyte contractility by a minimum of 13% and a maximum of 26% with/without 100 nM 17β-Estradiol. ♀ myocytes were immune to the effects of hypoxia, even exhibiting a slight increase in their peak calcium compared to control conditions, arguably because of the addition of isoproterenol. ♂ myocytes on the other hand, had an overall decrease in excitation-contraction coupling during hypoxia which was made worse by OR stimulation.

Conclusion: ♀ myocytes are immune to the detrimental effects of δ and κ OR stimulation.