Persisting chemosensory dysfunction in COVID-19 - a cross-sectional population-based survey

BACKGROUND

Chemosensory dysfunction (CD) has been reported as a common symptom of SARS-CoV-2 infection, but it is not well understood whether and for how long changes of smell, taste and chemesthesis persist in infected individuals.

METHODOLOGY

Unselected adult residents of the German federal state of Schleswig-Holstein with Polymerase Chain Reaction (PCR)-test-confirmed SARS-CoV-2 infection were invited to participate in this large cross-sectional study. Data on the medical history and subjective chemosensory function of participants were obtained through questionnaires and visual analogue scales (VAS). Olfactory function (OF) was objectified with the Sniffin Sticks test (SST), including threshold (T), discrimination (D) and identification (I) test as well as summarized TDI score, and compared to that in healthy controls. Gustatory function (GF) was evaluated with the suprathreshold taste strips (TS) test, and trigeminal function was tested with an ampoule containing ammonia.

RESULTS

Between November 2020 and June 2021, 667 infected individuals (mean age: 48.2 years) were examined 9.1 months, on average, after positive PCR testing. Of these, 45.6% had persisting subjective olfactory dysfunction (OD), 36.2% had subjective gustatory dysfunction (GD). Tested OD, tested GD and impaired trigeminal function were observed in 34.6%, 7.3% and 1.8% of participants, respectively. The mean TDI score of participants was significantly lower compared to healthy subjects. Significant associations were observed between subjective OD and GD, and between tested OD and GD.

CONCLUSION

Nine months after SARS-CoV-2 infection, OD prevalence is significantly increased among infected members of the general population. Therefore, OD should be included in the list of symptoms collectively defining Long-COVID.

Evidence for stronger discrimination between conspecific and heterospecific mating partners in sexual vs. asexual female freshwater snails

Once-useful traits that no longer contribute to fitness tend to decay over time. Here, we address whether the expression of mating-related traits that increase the fitness of sexually reproducing individuals but are likely less useful or even costly to asexual counterparts seems to exhibit decay in the latter. Potamopyrgus antipodarum is a New Zealand freshwater snail characterized by repeated transitions from sexual to asexual reproduction. The frequent coexistence of sexual and asexual lineages makes P. antipodarum an excellent model for the study of mating-related trait loss. Under the presumption (inherent in the Biological Species Concept) that failure to discriminate between conspecific and heterospecific mating partners represents a poor mate choice, we used a mating choice assay including sexual and asexual P. antipodarum females and conspecific (presumed better choice) vs. heterospecific (presumed worse choice) males to evaluate the loss of behavioral traits related to sexual reproduction. We found that sexual females engaged in mating behaviors with conspecific mating partners more frequently and for a greater duration than with heterospecific mating partners. By contrast, asexual females mated at similar frequency and duration as sexual females, but did not mate more often or for longer duration with conspecific vs. heterospecific males. While further confirmation will require inclusion of a more diverse array of sexual and asexual lineages, these results are consistent with a scenario where selection acting to maintain effective mate discrimination in asexual P. antipodarum is weak or ineffective relative to sexual females and, thus, where asexual reproduction is associated with the evolutionary decay of mating-related traits in this system.

Factors associated with health-related quality of life in heart failure in 23,000 patients from 40 countries: results of the global congestive heart failure research program

Background

Poor health-related quality of life (HRQL) is common in heart failure (HF) and strongly predicts death and HF hospitalization in all regions of the world. Understanding facors associated with HRQL could therefore lead to improved prognosis in HF patients. Despite that the majority of HF occurs in low- and middle-income countries, there are limited data characterizing self-perceived health HRQL and its correlates in these settings.

Purpose

To examine clinical and social correlates of HRQL in patients with HF from high- (HIC), upper middle- (UMIC), lower middle-(LMIC) and low-income (LIC) countries.

Methods

Between 2017 and 2020, we enrolled 23,292 patients with HF (32% inpatients, 61% men) from 40 countries in the Global Congestive Heart Failure Study. We recorded HRQL at baseline using Kansas City Cardiomyopathy Questionnaire (KCCQ)-12. In a cross-sectional analysis, we compared age- and sex-adjusted mean KCCQ-12 summary scores (SS: 0–100, higher=better) between patients from different country income levels. We used multivariable linear regression examining correlations (estimates expressed as β-coefficients) of KCCQ-12-SS with sociodemographic-, comorbidity-, treatment- and symptom-covariates. The adjusted model (37 covariates) was informed by univariable findings, clinical importance and backward selection. We used partial R2-estimates to understand the contribution to the variability in KCCQ-12-SS of 4 different groups of covariates. (sociodemographic, comorbidities, treatments and signs and symptoms of congestion).

Results

Mean age was 63 years and 40% were in NYHA class III–IV. Average HRQL was 55± SD 0.5. It was 62.5 (95% CI 62.0–63.1) in HIC, 56.8 (56.1–57.4) in UMIC, 48.6 (48.0–49.3) in LMIC, and 38.5 (37.3–39.7) in LICs (p<0.0001). Strong correlates (β-coefficient [95% CI]) of KCCQ-12-SS were NYHA class III vs class I/II (−12.1 [−12.8 to −11.4] and class IV vs. class I/II (−16.5 [−17.7 to −15.3]), effort dyspnea (−9.5 [−10.2 to −8.8]) and living in LIC vs. HIC (−5.8 [−7.1 to −4.4]). Symptoms explained most of the KCCQ-12-SS variability (partial R2=0.32 of total adjusted R2=0.51), followed by sociodemographic factors (R2=0.12). Results were consistent in populations across income levels.

Conclusion

The most important correlates of HRQL in HF patients relate to HF symptom severity, irrespective of country-income level. Improved symptom control may have a big impact on HRQL, especially in LICs.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Bayer AG

P5450Evening levels and circadian changes of salivary cortisol predict adverse events in heart failure patients with comorbid depression - a MOOD-HF substudy

Background

Depression is frequent in heart failure (HF) and associated with adverse clinical outcomes. The randomized MOOD-HF trial showed that in depressed patients with systolic heart failure (HF) the selective serotonin reuptake inhibitor escitalopram (E) improved neither survival nor depression compared to placebo (P). The hypothalamic-pituitary-adrenocortical axis is known to be altered in depression or HF. This MOOD-HF substudy aimed to clarify whether circadian salivary cortisol levels (SCL) were predictive of adverse events in depressed MOOD-HF participants and whether outcomes differed according to treatment with E.

Methods

MOOD-HF participants (all suffering from symptomatic systolic HF with left ventricular ejection fraction (LVEF) <45% and current major depression) were eligible for the present analysis if providing samples for SCL determination (luminescence immunoassay) at baseline visit (BL) and if not on oral glucocorticosteroid therapy. Depression severity was determined with the Montgomery–Åsberg Depression Rating Scale (MADRS) and LVEF measured by echocardiography.

Results

In the total study cohort (146 patients on E, 147 on P) median morning SCL at BL was 0.210 μg/dL (IQR 0.141–0.338 μg/dL) and median evening (pm) SCL 0.067 μg/dL (0.036–0.128 μg/dL, p<0.001). Median circadian change was 0.124 μg/dL (0.044–0.239 μg/dL). In patients with BL pm-SCL above the median MADRS-score was 21.7±9.1 and LVEF 33.7±8.4% respectively, in patients with pm-SCL below the median these values were 19.6±9.1 and 36.5±7.8% (p=0.048; p=0.004).

During 12 months follow-up the composite endpoint (all-cause death or rehospitalization) occurred least in E-treated patients with low pm-SCL and most often in E-treated patients with high pm-SCL (HR 2.02, 95% CI 1.12–3.65, p=0.010); patients on P had comparable event rates irrespective of BL pm-SCL (Figure A). Thus, numerically patients on E with low BL pm-SCL had lower event rates compared with corresponding P-treated patients (HR 0.76 (0.41–1.40, p=0.796)), while patients with high BL pm-SCL had higher event rates (HR 1.29 (0.74–2.24, p=0.799)) than corresponding P-treated patients. Patients with circadian SCL changes above the median receiving P experienced the composite primary endpoint least, while both subgroups with circadian SCL changes below the median and also patients with circadian SCL changes above the median on E had higher event rates (HR 0.66 (0.45–0.97, p=0.039), Figure B).

Conclusion

In depressed patients with systolic HF high pm-SCL are associated with more severe disease (depression and cardiac dysfunction). Extending primary MOOD-HF results indicating unfavourable outcomes related to E, the current findings suggest a SCL x treatment interaction with higher event rates in (sicker) patients with high pm-SCL and lower event rates in (less sick) patients with low pm-SCL when treated with the antidepressant. Low circadian changes of SCL were always associated with higher event rates.

Acknowledgement/Funding

BMBF (Grant 01 KG0702) and Lundbeck A/S Denmark

Altered conditioned fear behavior in glutamate decarboxylase 65 null mutant mice

We investigated the involvement of the 65 kDa isoform of glutamic acid decarboxylase (GAD65) and GAD65-mediated gamma-aminobutyric acid (GABA) synthesis in the formation and expression of Pavlovian fear memory. To this end, behavioral, endocrine and autonomic parameters were examined during conditioned fear retrieval of mice with targeted ablation of the GAD65 gene (GAD65-/- mice). These mutant mice were found to display specific fear behavior (freezing, escape), as well as autonomic (increased defecation) and endocrine activation (increased plasma corticosterone) during fear memory retrieval. However, freezing was reduced and flight and escape behavior were increased in GAD65-/- mice compared to their wild type and heterozygous littermates, while corticosterone levels and defecation rates did not differ between genotypes. Active defensive behavior of GAD65-/- mice was observed during both auditory cued and contextual retrieval of fear memory, as well as immediately after conditioning. These data indicate a selectively altered behavioral fear response in GAD65-/- mice, most likely due to deficits in threat estimation or the elicitation of appropriate conditioned fear behavior, and suggest that GAD65 is a genetic determinant of conditioned fear behavior. GAD65-/- mice provide a valuable tool to further dissect the GABAergic mechanisms involved in fear and anxiety and to model GABA-related neurological and psychiatric disorders.

Protective effect of parvalbumin on excitotoxic motor neuron death

The mechanism responsible for the selective vulnerability of motor neurons in amyotrophic lateral sclerosis (ALS) is poorly understood. Several lines of evidence indicate that susceptibility of motor neurons to Ca(2+) overload induced by excitotoxic stimuli is involved. In this study, we investigated whether the high density of Ca(2+)-permeable AMPA receptors on motor neurons gives rise to higher Ca(2+) transients in motor neurons compared to dorsal horn neurons. Dorsal horn neurons were chosen as controls as these cells do not degenerate in ALS. In cultured spinal motor neurons, the rise of the cytosolic Ca(2+) concentration induced by kainic acid (KA) and mediated by the AMPA receptor was almost twice as high as in spinal neurons from the dorsal horn. Furthermore, we investigated whether increasing the motor neuron's cytosolic Ca(2+)-buffering capacity protects them from excitotoxic death. To obtain motor neurons with increased Ca(2+) buffering capacity, we generated transgenic mice overexpressing parvalbumin (PV). These mice have no apparent phenotype. PV overexpression was present in the central nervous system, kidney, thymus, and spleen. Motor neurons from these transgenic mice expressed PV in culture and were partially protected from KA-induced death as compared to those isolated from nontransgenic littermates. PV overexpression also attenuated KA-induced Ca(2+) transients, but not those induced by depolarization. We conclude that the high density of Ca(2+)-permeable AMPA receptors on the motor neuron's surface results in high Ca(2+) transients upon stimulation and that the low cytosolic Ca(2+)-buffering capacity of motor neurons may contribute to the selective vulnerability of these cells in ALS. Overexpression of a high-affinity Ca(2+) buffer such as PV protects the motor neuron from excitotoxicity and this protective effect depends upon the mode of Ca(2+) entry into the cell.

Identification of genes expressed in the amygdala during the formation of fear memory

In this study we describe changes of gene expression that occur in the basolateral complex of the mouse amygdala (BLA) during the formation of fear memory. Through the combination of a behavioral training scheme with polymerase chain reaction-based expression analysis (subtractive hybridization and virtual Northern analysis) we were able to identify various gene products that are increased in expression after Pavlovian fear conditioning and are of potential significance for neural plasticity and information storage in the amygdala. In particular, a key enzyme of monoamine metabolism, aldehyde reductase, and the protein sorting and ubiquitination factor Praja1, showed pronounced and learning-specific induction six hours after fear conditioning training. Aldehyde reductase and Praja1, including a novel alternatively spliced isoform termed Praja1a, were induced in the BLA depending on the emotional stimulus presented and showed different expression levels in response to associative conditioning, training stress, and experience of conditioned fear. Stress and fear were further found to induce various signal transduction factors (transthyretin, phosphodiesterase1, protein kinase inhibitor-alpha) and structural reorganization factors (e.g., E2-ubiquitin conjugating enzyme, neuroligin1, actin, UDP-galactose transporter) during training. Our results show that the formation of Pavlovian fear memory is associated with changes of gene expression in the BLA, which may contribute to neural plasticity and the processing of information about both conditioned and unconditioned fear stimuli.

Recovery of emotional behaviour in neural cell adhesion molecule (NCAM) null mutant mice through transgenic expression of NCAM180

In the present study we further investigate functions of the neural cell adhesion molecule (NCAM) in the mature central nervous system and its implications for animal behaviour. To this end we generated transgenic mice expressing the major NCAM isoform with the largest cytoplasmic domain, NCAM180, under control of a promoter for the small form neurofilament gene. Transgenic mice were also bred with mice deficient in endogenous NCAM (Ncam-/- mice) so that effects of NCAM180 could be analysed in the presence and absence of endogenous NCAM. While overexpression of transgenic NCAM180 was without apparent behavioural or morphological effect, its expression in Ncam-/- mice counteracted NCAM ablation-induced aggressive, anxiety-like and antidepressant-like behaviour. It furthermore prevented a hypersensitivity of Ncam-/- mice to the anxiolytic serotonin1A (5-HT1A) receptor agonist buspirone. Such recovery of emotional behaviour and behavioural 5-HT1A response occurred in spite of misdevelopment of the olfactory bulb and hippocampus that is characteristic of Ncam-/- mice, and without an apparent change in the expression of 5-HT1A binding sites in the brain. Hippocampus- and amygdala-dependent learning, though disturbed in Ncam-/- mice, remained unaffected by the transgenic NCAM180. We suggest an involvement of NCAM180-mediated cell recognition processes in the serotonergic modulation of emotional behaviour in adult mice.

Postnatal development of a GABA deficit and disturbance of neural functions in mice lacking GAD65

The 65-kDa isoform of glutamic acid decarboxylase (GAD65) is believed to play an essential role for GABA synthesis in the central nervous system. Using mice with targeted disruption of the GAD65 gene (GAD65(-/-) mice) we investigated the contribution of GAD65 to GABA synthesis in different brain areas during postnatal development and in adulthood. In the amygdala, hypothalamus and parietal cortex of GAD65(+/+) mice an increase of GABA levels was observed during postnatal development, most prominently between the first and second month after birth. This increase appeared to be dependent on GAD65, as it was delayed by 2 months in GAD65(+/-) mice and was not observed in GAD65(-/-) mice. Likely as a consequence of their GABA deficit, adult GAD65(-/-) mice showed a largely abnormal neural activity with frequent paroxysmal discharges and spontaneous seizures. They furthermore displayed increased anxiety-like behaviour in a light/dark avoidance test and reduced intermale aggression, as well as a reduced forced-swimming-induced immobility indicative of an antidepressant-like behavioural change. Adult GAD65(+/-) mice did not show behavioural disturbances except for a reduced aggressive behaviour that was comparable to that in GAD65(-/-) mice. We conclude that GAD65-mediated GABA synthesis may be crucially involved in control of emotional behaviour and indispensable for a tonic inhibition that prevents the development of hyperexcitability in the maturating central nervous system. Aggressive, and possibly other social behaviour may be especially prone to regulation through GAD65-mediated GABA synthesis.