Numerical modeling of microplastic interaction with fine sediment under estuarine conditions

Microplastic (MP) pollution is an important challenge for human life which has consequently affected the natural system of other organisms. Mismanagement and also careless handling of plastics in daily life has led to an accelerating contamination of air, water and soil compartments with MP. Under estuarine conditions, interactions with suspended particulate matter (SPM) like fine sediment in the water column play an important role on the fate of MP. Further studies to better understand the corresponding transport and accumulation mechanisms are required. This paper aims at providing a new modeling approach improving the MP settling velocity formulation based on higher suspended fine sediment concentrations, as i.e. existent in estuarine turbidity zones (ETZ). The capability of the suggested approach is examined through the modeling of released MP transport in water and their interactions with fine sediment (cohesive sediment/fluid mud). The model results suggest higher concentrations of MP in ETZ, both in the water column as well as the bed sediment, which is also supported by measurements. The key process in the modeling approach is the integration of small MP particles into estuarine fine sediment aggregates. This is realized by means of a threshold sediment concentration, above which the effective MP settling velocity increasingly approaches that of the sediment aggregates. The model results are in good agreement with measured MP mass concentrations. Moreover, the model results also show that lighter small MP particles can easier escape the ETZ towards the open sea.

Early in-hospital discontinuation of aspirin following coronary stent implantation in patients with indication for direct oral anticoagulation

Background and purpose

5–10% of patients undergoing percutaneous coronary intervention (PCI) have an indication for oral anticoagulation (OAC). Triple therapy, i.e. anticoagulation plus dual antiplatelet therapy, is associated with a high bleeding rate. Discontinuation of aspirin while continuing direct OAC (DOAC) and a P2Y12 inhibitor (so-called dual therapy) after PCI, was investigated in four randomized trials demonstrating a reduction in bleeding without significant differences in ischemic events. Since randomization was performed several days after the index PCI, these trials allowed for a short period of triple therapy. Whether exclusive procedural application of aspirin and early discontinuation of aspirin at the first postprocedural day is safe, is unknown and was the scope of this work.

Methods and results

We retrospectively analysed 3613 patients (4564 PCIs) treated from 2017 to 2020 at our centre. 871 (24.1%) patients (1059 PCIs, 23.2%) had an indication for OAC. In 284 PCIs with stenting, patients received DOAC (71.8% Rivaroxaban, 25.7% Apixaban, 1.8% Dabigatran, 0.7% Edoxaban) + P2Y12 inhibitor (100% clopidogrel) + aspirin only at the day of procedure (group 1). In 52 PCIs with stenting, patients received DOAC (59.6% Rivaroxaban, 34.6% Apixaban, 1.9% Dabigatran, 3.9% Edoxaban) + P2Y12 inhibitor (100% clopidogrel) + 100 mg aspirin/d at ≥1 postprocedural day (group 2). Based on our local patient database, we analysed the rate of ischemic events (myocardial infarction, stent thrombosis, stroke/transient ischemic attack (TIA), pulmonary/systemic embolism (PE/SE), deep vein thrombosis) as well as major and minor bleeding according to the Thrombolysis in Myocardial Infarction (TIMI) criteria during hospitalisation. Data are presented as mean±standard deviation or median (range).

Baseline characteristics were similar (group 1 vs. group 2: 74.3% vs. 73.1% male, age 75.9±8.5 vs. 74.3±9.3 years, atrial fibrillation 91.2% vs. 88.5%), except previous PE (3.5% vs. 11.5%; p=0.024), type of preprocedural DOAC (Rivaroxaban 52.5% vs. 34.6%; p=0.023) and creatinine clearance (62.4±19.7 vs. 68.9±20.3 ml/min; p=0.029). Median duration of postprocedural hospitalisation was 1 day for both groups (0–20 days vs. 1–21 days). In both groups, one TIA occurred (p=0.292), there were no other ischemic events. 36 (12.7%) bleeding events occurred in group 1 and 11 (21.2%) in group 2 (p=0.126). A subgroup analysis of cases being hospitalised for ≥2 postprocedural days (group 1: 87 cases, median 4 (2–20) days; group 2: 20 cases, median 2 (2–21) days) found no ischemic events and no difference regarding bleeding events (34.5% vs. 45.0%; p=0.443).

Conclusions

Exclusive procedural application of aspirin and start of dual therapy at the first postprocedural day appears safe regarding ischemic events in a real-world population. Nearly ¼ of patients undergoing PCI had an indication for OAC, which is much more frequent than previously reported.

Funding Acknowledgement

Type of funding sources: None.

Retrospective comparison of Resting Full-cycle Ratio (RFR) and Fractional Flow Reserve (FFR) in a coronary artery disease cohort

Background

The fractional flow reserve (FFR) is the gold standard for the assessment of the physiological severity of coronary artery disease. Measurement of FFR requires administration of a vasodilator (commonly adenosine) to achieve maximum hyperemia. The development of resting indices that do not require the administration of adenosine is of great importance. A novel hyperemia-free resting index is the “resting full cycle ratio” (RFR), which corresponds to the lowest pressure distal to the stenosis in relation to the aortic pressure during the entire cardiac cycle. The aim of the present study was to examine the diagnostic accuracy of RFR compared to FFR.

Methods

The study included consecutive patients undergoing pressure wire studies for standard indications at our university hospital from March 9, 2015 to February 15, 2019. Lesions with FFR ≤0.80 were classified as functionally significant. The RFR values were calculated retrospectively from the curves of the FFR measurements, using a point in time before adenosine administration, so that non-hyperemic resting conditions were present.

Results

A total of 635 patients with 733 coronary lesions were investigated using FFR. The average age of the subjects was 68.1±10.7 years. 459 (72.3%) were male. The distribution of the lesions was as follows: LAD: 444 (60.5%), RCA: 140 (19.1%), RCX: 127 (17.3%), RIM: 12 (1.6), LM: 6 (0.9%) and bypasses: 4 (0.5). Overall, the FFR and RFR values were 0.841±0.08 and 0.91±0.06. The RFR showed a significant correlation with the FFR (Table 1). Diagnostic accuracy of the RFR compared to the FFR was highest at a cut-off value of 0.89. This could be demonstrated using the receiver operating characteristic curve (Picture 1).

In 408 measurements, coronary stenoses that were not hemodynamically relevant were found (FFR>0.8 and RFR>0.89). 164 measurements showed hemodynamically relevant coronary stenoses (FFR ≤0.8 and RFR ≤0.89). In 66 lesions, the FFR measurement showed hemodynamic relevance and the RFR measurement did not, whereas in 95 patients the RFR measurement showed hemodynamic relevance and the FFR values were normal.

Conclusions

The RFR as a new resting index has a significant correlation with the FFR after adenosine administration. In 22% of the measurements, a different therapeutic decision would have been made based on the RFR vs. the FFR. A randomized study should therefore investigate whether a RFR-guided approach is non-inferior to a FFR-guided approach in terms of avoiding cardiovascular complications.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Abbott Laboratories

Pulmonary hypertension and valvular heart disease

Pulmonary hypertension (PH) is an important contributor to morbidity and mortality in patients with left-sided heart disease, including valvular heart disease. In this context, elevated left atrial pressure primarily leads to the development of post-capillary PH. Despite the fact that repair of left-sided valvular heart disease by surgical or interventional approaches will improve PH, recent studies have highlighted that PH (pre- or post-interventional) remains an important predictor of long-term outcome. Here, we review the current knowledge on PH in valvular heart disease taking into account new hemodynamic PH definitions, and the distinction between post- and pre-capillary components of PH. A specific focus is on the precise characterization of hemodynamics and cardiopulmonary interaction, and on potential strategies for the management of residual PH after mitral or aortic valve interventions. In addition, we highlight the clinical significance of tricuspid regurgitation, which may occur as a primary condition or as a consequence of PH and right heart dilatation (functional). In this context, proper patient selection for potential tricuspid valve interventions is crucial. Finally, the article highlights gaps in evidence, and points toward future perspectives.

[Certification : Pro: indispensable component of quality]

Certification is a critical component of quality assurance in medicine. From the certification of individual persons, through units and up to whole hospitals, certification stimulates testing and optimization of treatment processes, thereby improving the quality of care. Minimum case numbers needed to acquire a certificate are an important and objective attribute of quality. Advantages of certification include an improved treatment of patients, structured training of new employees and enhanced cost efficiency.

[Platelet inhibition in patients with coronary, cerebral and peripheral macroangiopathy : What, when and how long?]

BACKGROUND

Inhibition of platelet aggregation can reduce the rate of vascular events in patients with coronary artery disease, carotid artery stenosis and symptomatic peripheral arterial disease. The choice of platelet inhibitors in monotherapy and combination therapy as well as the duration of dual platelet inhibition depend on the clinical situation and individual patient characteristics.

GOAL

The present review summarizes the latest data from clinical trials and recommendations regarding platelet inhibition in coronary, cerebral and peripheral arterial disease.

DATA

A large number of randomized trials on platelet inhibition in different clinical situations have been performed, allowing evidence-based recommendations on the choice of drugs and duration of treatment. Moreover, new guidelines of European professional societies on platelet inhibition in patients with coronary, cerebral and peripheral arterial disease have been recently published.

CONCLUSION

Based on latest randomized trials and major society guidelines, a number of recommendations on platelet inhibition in stable coronary artery disease, after stent implantation, after acute coronary syndromes and in cerebral and peripheral arterial disease can be made.

[Baroreflex activation therapy. A novel interventional approach to treat heart failure with reduced ejection fraction]

Sympathovagal imbalance plays an important role in the progression of heart failure with reduced ejection fraction. Baroreflex activation therapy (BAT), i. e. electrical stimulation of baroreceptors located at the carotid sinus, can reduce sympathetic and enhance parasympathetic tone. Large animal studies on BAT demonstrated improvements in cardiac function, arrhythmogenic risk and a survival benefit compared to untreated controls. The recently published Neo Randomized Heart Failure Study, the first multicenter, randomized and controlled trial of optimal medical and device therapy alone or plus BAT in patients with a left ventricular ejection fraction ≤ 35 %, demonstrated a reasonable safety profile of BAT in this severely ill patient population and no relevant interactions with other devices. The study found significant improvements in the New York Heart Association (NYHA) class of heart failure, quality of life as well as 6 min walking distance and data pointed to a reduction in hospitalization rates. Moreover, N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were significantly reduced. This review gives an overview on BAT for the treatment of heart failure with reduced ejection fraction, from the rationale and animal experiments to the most recent clinical data and future perspectives.

Nasopharyngeally and vertex recorded P300's in normal subjects

The P300 waveform has been associated with cognitive activity during information processing, and the hippocampus has been discussed as a possible generator of this waveform. This being the case some would argue that it should be possible to record the P300 with a shorter latency and greater amplitude from an electrode placed as near the hippocampus as possible. Under local anaesthesia we inserted a specially constructed needle electrode through the left nostril in the recessus pharyngeus close to the hippocampus. The results did not support the hippocampal hypothesis. Nasopharyngeally recorded P300's were found to have significantly decreased amplitudes and extended latencies when compared to vertex recordings.

Abnormal glucocorticoid dependent increase of spiperone binding sites on lymphocytes from schizophrenics in vitro

The attempt was made to revise experimentally the concept of spiperone binding to human peripheral lymphocytes as a peripheral marker for schizophrenic disorder. Although it was not possible to detect differences in spiperone binding in freshly isolated lymphocytes from schizophrenics and controls, a significant increase in spiperone binding became apparent when the lymphocytes from patients were cultured in vitro in the presence of physiological concentrations of glucocorticoids. From our findings we have to assume that glucocorticoid-dependent regulation of the gene(s) containing the coding for spiperone binding sites could be functionally affected in distinct forms of schizophrenic psychosis. The glucocorticoid-induced increase of spiperone binding of human lymphocytes could represent a dynamic peripheral marker system. It further has to be investigated whether this concept of a regulatory dysfunction, as observed in lymphocytes from schizophrenic patients, can be applied to the CNS in general.

Neuromuscular, autonomic and central cholinergic hyperactivity associated with thymoma and acetylcholine receptor-binding antibody

Two cases of a neuromuscular hyperactivity syndrome associated with a proliferative thymoma and high serum titres of acetylcholine receptor (AChR) antibody with no signs of myasthenia are reported. The clinical and electrodiagnostic findings indicated generalized cholinergic hyperactivity at the neuromuscular junction and in the autonomic and central nervous system, resulting in generalized myokymia, excessive sweating and intermittent psychotic behaviour. The association with thymoma and raised AChR antibody suggests that this syndrome represents a unique type of autoimmune disease, in which antibodies against the AChR facilitate rather than inhibit cholinergic action. This conclusion is supported by the remission of symptoms after thymectomy and with immunosuppressive therapy in one case.

Rabies virus infection selectively impairs membrane receptor functions in neuronal model cells

A persistent infection with rabies virus (HEP-Flury) was established in the CNS-derived hybrid cell line 108CC15 which possesses specific membrane receptors for prostaglandins, catecholamines and acetylcholine. We report a differential virus influence on the specific receptor response to PGE, isoproterenol and acetycholine as indicated by typical changes of the intracellular cyclic AMP levels. As the adenylate cyclase activity was unchanged in infected cells in vitro, a selective virus influence on specific receptors themselves or their coupling to the cAMP synthesizing system must be considered.

Impairment of hormone dependent signal transfer by chronic SSPE virus infection

In a CNS-derived cell line, the cellular response to hormonal stimulation, represented by the rise of intracellular cAMP levels, is impaired under the influence of a persisting neurotropic virus infection. This dysfunction is caused by the decrease in adenylate cyclase activity, most probably due to the virus-induced loss of active catalytic units.

Interferon enhances the fragility of lysosomes in L-929 mouse fibroblasts

Infection of interferon-treated L-929 mouse fibroblasts with vaccinia WR virus is followed by severe cytolysis within 3 to 4 h. It is shown that this cytolysis cannot be caused by enzymes released from lysosomes into the cytosol. However, there is evidence that homologous interferon has a noxious effect on lysosomes. This phenomenon appears to be another aspect of the anticellular functions of interferon.