In-depth mechanistic analysis including high-throughput RNA sequencing in the prediction of functional and structural cardiotoxicants using hiPSC cardiomyocytes

BACKGROUND

Cardiotoxicity remains one of the most reported adverse drug reactions that lead to drug attrition during pre-clinical and clinical drug development. Drug-induced cardiotoxicity may develop as a functional change in cardiac electrophysiology (acute alteration of the mechanical function of the myocardium) and/or as a structural change, resulting in loss of viability and morphological damage to cardiac tissue.

RESEARCH DESIGN AND METHODS

Non-clinical models with better predictive value need to be established to improve cardiac safety pharmacology. To this end, high-throughput RNA sequencing (ScreenSeq) was combined with high-content imaging (HCI) and Ca2+ transience (CaT) to analyze compound-treated human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs).

RESULTS

Analysis of hiPSC-CMs treated with 33 cardiotoxicants and 9 non-cardiotoxicants of mixed therapeutic indications facilitated compound clustering by mechanism of action, scoring of pathway activities related to cardiomyocyte contractility, mitochondrial integrity, metabolic state, diverse stress responses and the prediction of cardiotoxicity risk. The combination of ScreenSeq, HCI and CaT provided a high cardiotoxicity prediction performance with 89% specificity, 91% sensitivity and 90% accuracy.

CONCLUSIONS

Overall, this study introduces mechanism-driven risk assessment approach combining structural, functional and molecular high-throughput methods for pre-clinical risk assessment of novel compounds.

Successful Percutaneous Mechanical Suction Thrombectomy of Extracorporeal Filtration System Following Bilateral Lung Transplantation Secondary to COVID-Pneumonia

Introduction

COVID infections show increased risk of thromboembolic events. We report a case of a 43 year old male with acute Covid-19 pneumonia necessitating veno-venous ECMO and RVAD support as bridge to pulmonary transplantation. At transplant, he had thrombus along his extra-corporeal pulmonary artery cannula necessitating percutaneous mechanical thrombectomy.

Case Report

The patient presented as a transfer to our institution with COVID-19 related ARDS in refractory respiratory failure with multiple bronchopleural fistulas. Shortly after admission, veno-venous ECMO was initiated and over time was fully ECMO dependent due to extensive tissue destruction with essentially no functional lung tissue. He was converted to right internal jugular-left subclavian vein ECMO-RVAD configuration while assessing for transplantation. After 135 days of support, a suitable donor was identified and was taken for bilateral lung transplantation with ECMO/RVAD support. This was complicated by a frozen chest, massive transfusion, and primary graft dysfunction necessitating postoperative maintenance of circulatory support. Intraoperatively, a large thrombus burden was found along the pulmonary artery outflow cannula. His chest was left open at that time while his graft recovered. Three days later, a percutaneous suction thrombectomy device was inserted through his right femoral vein and under TEE guidance, he underwent suction thrombectomy of the pulmonary artery cannula clot burden (Figure 1). He was decannulated and underwent chest closure thereafter. He was anticoagulated post-operatively and has not had any further thromboembolic events.

Summary

Acute COVID-19 infection leads to a known increased risk of thromboembolic phenomena. We present an interesting approach to removal of ECMO-cannula associated thrombus in severe SARS-CoV-2 infection necessitating bilateral lung transplantation.

mRNA quality control is bypassed for immediate export of stress-responsive transcripts

Cells grow well only in a narrow range of physiological conditions. Surviving extreme conditions requires the instantaneous expression of chaperones that help to overcome stressful situations. To ensure the preferential synthesis of these heat-shock proteins, cells inhibit transcription, pre-mRNA processing and nuclear export of non-heat-shock transcripts, while stress-specific mRNAs are exclusively exported and translated. How cells manage the selective retention of regular transcripts and the simultaneous rapid export of heat-shock mRNAs is largely unknown. In Saccharomyces cerevisiae, the shuttling RNA adaptor proteins Npl3, Gbp2, Hrb1 and Nab2 are loaded co-transcriptionally onto growing pre-mRNAs. For nuclear export, they recruit the export-receptor heterodimer Mex67-Mtr2 (TAP-p15 in humans). Here we show that cellular stress induces the dissociation of Mex67 and its adaptor proteins from regular mRNAs to prevent general mRNA export. At the same time, heat-shock mRNAs are rapidly exported in association with Mex67, without the need for adapters. The immediate co-transcriptional loading of Mex67 onto heat-shock mRNAs involves Hsf1, a heat-shock transcription factor that binds to heat-shock-promoter elements in stress-responsive genes. An important difference between the export modes is that adaptor-protein-bound mRNAs undergo quality control, whereas stress-specific transcripts do not. In fact, regular mRNAs are converted into uncontrolled stress-responsive transcripts if expressed under the control of a heat-shock promoter, suggesting that whether an mRNA undergoes quality control is encrypted therein. Under normal conditions, Mex67 adaptor proteins are recruited for RNA surveillance, with only quality-controlled mRNAs allowed to associate with Mex67 and leave the nucleus. Thus, at the cost of error-free mRNA formation, heat-shock mRNAs are exported and translated without delay, allowing cells to survive extreme situations.

Nuclear Export of Pre-Ribosomal Subunits Requires Dbp5, but Not as an RNA-Helicase as for mRNA Export

The DEAD-box RNA-helicase Dbp5/Rat8 is known for its function in nuclear mRNA export, where it displaces the export receptor Mex67 from the mRNA at the cytoplasmic side of the nuclear pore complex (NPC). Here we show that Dbp5 is also required for the nuclear export of both pre-ribosomal subunits. Yeast temperature-sensitive dbp5 mutants accumulate both ribosomal particles in their nuclei. Furthermore, Dbp5 genetically and physically interacts with known ribosomal transport factors such as Nmd3. Similar to mRNA export we show that also for ribosomal transport Dbp5 is required at the cytoplasmic side of the NPC. However, unlike its role in mRNA export, Dbp5 does not seem to undergo its ATPase cycle for this function, as ATPase-deficient dbp5 mutants that selectively inhibit mRNA export do not affect ribosomal transport. Furthermore, mutants of GLE1, the ATPase stimulating factor of Dbp5, show no major ribosomal export defects. Consequently, while Dbp5 uses its ATPase cycle to displace the export receptor Mex67 from the translocated mRNAs, Mex67 remains bound to ribosomal subunits upon transit to the cytoplasm, where it is detectable on translating ribosomes. Therefore, we propose a model, in which Dbp5 supports ribosomal transport by capturing ribosomal subunits upon their cytoplasmic appearance at the NPC, possibly by binding export factors such as Mex67. Thus, our findings reveal that although different ribonucleoparticles, mRNAs and pre-ribosomal subunits, use shared export factors, they utilize different transport mechanisms.

Quality control of spliced mRNAs requires the shuttling SR proteins Gbp2 and Hrb1

Eukaryotic cells have to prevent the export of unspliced pre-mRNAs until intron removal is completed to avoid the expression of aberrant and potentially harmful proteins. Only mature mRNAs associate with the export receptor Mex67/TAP and enter the cytoplasm. Here we show that the two shuttling serine/arginine (SR)-proteins Gbp2 and Hrb1 are key surveillance factors for the selective export of spliced mRNAs in yeast. Their absence leads to the significant leakage of unspliced pre-mRNAs into the cytoplasm. They bind to pre-mRNAs and the spliceosome during splicing, where they are necessary for the surveillance of splicing and the stable binding of the TRAMP complex to spliceosome-bound transcripts. Faulty transcripts are marked for their degradation at the nuclear exosome. On correct mRNAs the SR proteins recruit Mex67 upon completion of splicing to allow a quality controlled nuclear export. Altogether, these data identify a role for shuttling SR proteins in mRNA surveillance and nuclear mRNA quality control.

Role of Ser-340 and Thr-341 in transmembrane domain IX of the Na+/proline transporter PutP of Escherichia coli in ligand binding and transport

The Na+/solute symporter family comprises more than 400 members of pro- and eukaryotic origin. Using the Na+/proline transporter PutP of Escherichia coli as a model, the role of two conserved residues, Ser-340 and Thr-341, is investigated to obtain insights into the mechanism of transport catalyzed by members of this family. Substitution of these amino acids alters the transport kinetics of cells and proteoliposomes containing the PutP variants significantly. In particular, the apparent affinities for Na+ and Li+ are reduced by 2 orders of magnitude or more. Also proline binding is affected, albeit to a lesser extent than ion binding. Thereby, the presence of a hydroxyl group at position 341 is essential for high affinity ligand binding. Furthermore, Cys placed at position 340 or 341 reacts with sulfhydryl reagents of different polarity, indicating accessibility from the water phase. In addition, Cys cross-linking suggests proximity of the residues to other amino acids previously shown to be crucial for ligand binding. For these reasons it is suggested that Ser-340 and Thr-341 are located in a ligand translocation pathway. Furthermore, it is proposed that the side chain of Thr-341 directly participates in Na+ binding.

Recurrent images and early memories in social phobia

A recent model [Clark, D. M. & Wells, A. (1995). A cognitive model of social phobia. In R. Heimberg, M. Liebowitz, D. A. Hope & F. R. Schneier (Eds.), Social phobia: diagnosis, assessment and treatment (pp. 69-93). New York: Guildford Press] suggests that a distorted image of one's public self lies at the heart of social phobia. A previous study of spontaneous imagery [Hackmann, A., Surawy, C. & Clark, D. M. (1998) Seeing yourself through others' eyes: a study of spontaneously occurring images in social phobia. Behavioural and Cognitive Psychotherapy, 26, 3-12] confirmed that patients with social phobia frequently report experiencing negative, distorted, observer-perspective images when in anxiety provoking social situations. In the present study, 22 patients with social phobia were given a semistructured interview which aimed to further explore the nature of social phobic imagery. All participants were able to identify negative spontaneous images that were recurrent in the sense that their content appeared to be relatively stable over time and across different feared social situations. Most recurrent images involved several sensory modalities. Most recurrent images were linked to memories of adverse social events that clustered in time around the onset of the disorder. Taken together, the results suggest that in patients with social phobia, early unpleasant experiences may lead to the development of excessively negative images of their social selves that are repeatedly activated in subsequent social situations and fail to update in the light of subsequent, more favourable experiences. Implications of the findings for the understanding and treatment of social phobia are discussed.

Brief cognitive therapy for panic disorder: a randomized controlled trial

Cognitive therapy (CT) is a specific and highly effective treatment for panic disorder (PD). Treatment normally involves 12-15 1-hr sessions. In an attempt to produce a more cost-effective version, a briefer treatment that made extensive use of between-sessions patient self-study modules was created. Forty-three PD patients were randomly allocated to full CT (FCT), brief CT (BCT), or a 3-month wait list. FCT and BCT were superior to wait list on all measures, and the gains obtained in treatment were maintained at 12-month follow-up. There were no significant differences between FCT and BCT. Both treatments had large (approximately 3.0) and essentially identical effect sizes. BCT required 6.5 hr of therapist time, including booster sessions. Patients' initial expectation of therapy success was negatively correlated with posttreatment panic-anxiety. Cognitive measures at the end of treatment predicted panic-anxiety at 12-month follow-up.

Brief cognitive therapy for panic disorder: a randomized controlled trial

Cognitive therapy (CT) is a specific and highly effective treatment for panic disorder (PD). Treatment normally involves 12-15 1-hr sessions. In an attempt to produce a more cost-effective version, a briefer treatment that made extensive use of between-sessions patient self-study modules was created. Forty-three PD patients were randomly allocated to full CT (FCT), brief CT (BCT), or a 3-month wait list. FCT and BCT were superior to wait list on all measures, and the gains obtained in treatment were maintained at 12-month follow-up. There were no significant differences between FCT and BCT. Both treatments had large (approximately 3.0) and essentially identical effect sizes. BCT required 6.5 hr of therapist time, including booster sessions. Patients' initial expectation of therapy success was negatively correlated with posttreatment panic-anxiety. Cognitive measures at the end of treatment predicted panic-anxiety at 12-month follow-up.

An experimental investigation of the role of safety-seeking behaviours in the maintenance of panic disorder with agoraphobia

This study evaluates the hypothesis that safety-seeking behaviours play an important role in maintaining anxiety because they prevent patients from benefiting from disconfirmatory experience. Patients suffering from panic disorder with agoraphobia carried out a behaviour test, closely followed by an experimental session, which included a brief (15 min) period of exposure during which participants either stopped or maintained within-situation safety-seeking behaviours. When the behaviour test was repeated within two days, patients who had stopped their safety-seeking behaviours during the experimental session showed a significantly greater decrease in catastrophic beliefs and anxiety than those who had maintained safety-seeking behaviour. This difference was also reflected in questionnaires measuring clinical anxiety. These results are consistent with the cognitive hypothesis.

Two psychological treatments for hypochondriasis. A randomised controlled trial

BACKGROUND

Hypochondriasis is generally considered difficult to manage. This study aimed to assess the effectiveness of cognitive therapy and to compare it with an equally credible, alternative treatment.

METHOD

Forty-eight patients with hypochondriasis were initially randomly assigned to either cognitive therapy, behavioural stress management or a no treatment waiting list control group. At the end of the waiting period, patients in the control group were randomly assigned to one of the two treatments. Assessments were at pre-, mid- and post-treatment or waiting list and at three-, six- and 12-month post-treatment follow-up.

RESULTS

Comparisons with the waiting list group showed both treatments were effective. Comparisons between the treatments showed that cognitive therapy was more effective than behavioural stress management on measures of hypochondriasis, but not general mood disturbance at mid-treatment and at post-treatment. One year after treatment patients who had received either treatment remained significantly better than before treatment, and on almost all measures the two therapies did not differ from each other.

CONCLUSIONS

Cognitive therapy is a specific treatment for hypochondriasis. Behavioural stress management is also effective but its specificity remains to be demonstrated.

Extension of the Rorschach--Hazlewood theoretical model for spin-lattice relaxation in biological systems to low frequencies

The water-biopolymer cross-relaxation model, proposed by H. E. Rorschach and C. F. Hazlewood (RH) [J. Magn. Reson. 70, 79 (1986)], explains the Larmor frequency dependence of T1 in many biological systems. However, the RH theory fails at low Larmor frequencies. In this paper, a more general version of the RH theory has been developed. This theory is valid at all frequencies. Use of the new expression for the spin-lattice relaxation rate (1/T1), earlier published experimental data in H2O/D2O bovine serum albumin, which had been measured over a wide frequency range (10 kHz to 100 MHz), were fitted over the entire frequency range. The agreement between theory and the experimental data is excellent. Theoretical expressions for the rotating-frame spin-lattice relaxation rate (1/T1(rho)) were also obtained.

Application to rat lung of the extended Rorschach-Hazlewood model of spin-lattice relaxation

The spin-lattice relaxation time T1 was measured in excised degassed (airless) rat lungs over the frequency range 6.7 to 80.5 MHz. The observed frequency dependence was fitted successfully to the water-biopolymer cross-relaxation theory proposed by H. E. Rorschach and C. F. Hazlewood (RH) [J. Magn. Reson. 70, 79 (1986)]. The rotating frame spin-lattice relaxation time T1(rho) was also measured in rat lung fragments over the frequency range 0.56 to 5.6 kHz, and the observed frequency dependence was explained with an extension of the RH model. The agreement between the theory and the experimental data in both cases is good.

Cognitive behaviour therapy for the chronic fatigue syndrome: a randomized controlled trial

OBJECTIVE

To evaluate the acceptability and efficacy of adding cognitive behaviour therapy to the medical care of patients presenting with the chronic fatigue syndrome.

DESIGN

Randomised controlled trial with final assessment at 12 months.

SETTING

An infectious diseases outpatient clinic.

SUBJECTS

60 consecutively referred patients meeting consensus criteria for the chronic fatigue syndrome.

INTERVENTIONS

Medical care comprised assessment, advice, and follow up in general practice. Patients who received cognitive behaviour therapy were offered 16 individual weekly sessions in addition to their medical care.

MAIN OUTCOME MEASURES

The proportions of patients (a) who achieved normal daily functioning (Karnofsky score 80 or more) and (b) who achieved a clinically significant improvement in functioning (change in Karnofsky score 10 points or more) by 12 months after randomisation.

RESULTS

Only two eligible patients refused to participate. All randomised patients completed treatment. An intention to treat analysis showed that 73% (22/30) of recipients of cognitive behaviour therapy achieved a satisfactory outcome as compared with 27% (8/30) of patients who were given only medical care (difference 47 percentage points; 95% confidence interval 24 to 69). Similar differences were observed in subsidiary outcome measures. The improvement in disability among patients given cognitive behaviour therapy continued after completion of therapy. Illness beliefs and coping behaviour previously associated with a poor outcome changed more with cognitive behaviour therapy than with medical care alone.

CONCLUSION

Adding cognitive behaviour therapy to the medical care of patients with the chronic fatigue syndrome is acceptable to patients and leads to a sustained reduction in functional impairment.

Chronic fatigue syndrome: a cognitive approach

Observations concerning the characteristics of patients who presented to a medical clinic with a principal complaint of chronic medically unexplained fatigue (Chronic Fatigue Syndrome or CFS) are described, including the cognitions (thoughts and assumptions) elicited from a sample of these patients who were treated using cognitive behavioural therapy. On the basis of these observations a cognitive theory of the aetiology of CFS is proposed. These observations have implications for the treatment of patients with CFS.

A comparison of cognitive therapy, applied relaxation and imipramine in the treatment of panic disorder

Recent studies have shown that cognitive therapy is an effective treatment for panic disorder. However, little is known about how cognitive therapy compares with other psychological and pharmacological treatments. To investigate this question 64 panic disorder patients were initially assigned to cognitive therapy, applied relaxation, imipramine (mean 233 mg/day), or a 3-month wait followed by allocation to treatment. During treatment patients had up to 12 sessions in the first 3 months and up to three booster sessions in the next 3 months. Imipramine was gradually withdrawn after 6 months. Each treatment included self-exposure homework assignments. Cognitive therapy and applied relaxation sessions lasted one hour. Imipramine sessions lasted 25 minutes. Assessments were before treatment/wait and at 3, 6, and 15 months. Comparisons with waiting-list showed all three treatments were effective. Comparisons between treatments showed that at 3 months cognitive therapy was superior to both applied relaxation and imipramine on most measures. At 6 months cognitive therapy did not differ from imipramine and both were superior to applied relaxation on several measures. Between 6 and 15 months a number of imipramine patients relapsed. At 15 months cognitive therapy was again superior to both applied relaxation and imipramine but on fewer measures than at 3 months. Cognitive measures taken at the end of treatment were significant predictors of outcome at follow-up.

Treatment of panic attacks using cognitive therapy without exposure or breathing retraining

Cognitive treatment of panic attacks is based on the hypothesis that panic results from the catastrophic misinterpretation of bodily sensations, and that changing such misinterpretations will block the occurrence of panic. The treatment normally involves an integrated set of cognitive and behavioural techniques. In a consecutive series of panic patients, a multiple baseline across subjects design was used to investigate whether a modified form of treatment involving only cognitive procedures could reduce panic attack frequency. The results provide preliminary evidence that cognitive procedures directed at changing misinterpretations of bodily sensations can reduce panic attack frequency, and also that cognitive procedures which do not target misinterpretations may not reduce panic.