5-HT-receptor-induced changes of the intracellular cAMP level monitored by a hyperpolarization-activated cation channel

The HvCNG channel from the moth Heliothis virescens is highly sensitive to cAMP concentrations ranging between 0.1 microM and 5 microM. This HvCNG channel was over-expressed in Spodoptera frugiperda (Sf.9) cells to measure endogenous cAMP levels. Hyperpolarization-activated inward currents were measured in the whole-cell patch-clamp configuration with pipettes filled with different cAMP concentrations to calibrate the system. Varying the cAMP concentration between 0 microM and 100 microM in the pipette, the half-maximal activation voltage ( V1/2) was shifted by +28.5+/-1.7 mV. The activation time constant (tau(a)) was used as a parameter for cAMP quantification because it was independent of the expression level of HvCNG channels. tau(a) changed from 1106+/-60 ms at 0 microM cAMP to 265+/-7 ms at a saturating concentration of 1 mM cAMP. A dose-response relationship yielded values of 0.6 microM for the half-maximal cAMP concentration and 1.5 for the Hill coefficient. Activation of endogenous adenylyl cyclases by 50 microM forskolin induced an elevation of the cAMP level by about 1.6+/-0.2 microM. Co-expressions of HvCNG channels in combination with the mouse 5-HT4a- or 5-HT1A- receptors and the corresponding Gs- or Gi-proteins were successful and allowed us to also verify receptor-induced changes of the cAMP level. Stimulation of m5-HT4a-receptors by 0.1 microM 5-HT induced an increase of cAMP of about 4.6+/-1.5 microM, whereas cAMP levels decreased from a control value of 1+/-0.2 microM to 0.41+/-0.1 microM after stimulation of the m5-HT1A-receptors.     

Neuronal plasticity in memory and learning abilities: Theoretical position and selective review

Neural plasticity of modality-nonspecific and modality-specific memory and learning abilities pertains to fluid intelligence and crystallized intelligence, respectively. The limbic system with the novelty neurons of the hippocampus interacts with the prefrontal cortex optimization of the orienting reflex and voluntary attention. Brain-derived neurotrophic factor produced by novelty neurons of the hippocampus contributes to long-term memory formation and improves learning abilities in a wide range of disciplines. Synergistic combination of stimulation with “analytical-specific visual perceptual patterns” and “optimally high” physiological activation of the bilateral electrodermal system optimizes the limbic system and prefrontal cortex activity as demonstrated by enhanced prefrontal N450 ERPs to a memory workload paradigm. This is accompanied by improvements in auditory retention tasks, word memorization, higher school achievement and marks, and an amelioration of “analytical-specific perceptual skills” as measured by the Mangina-Test. Intracerebral ERPs to a memory workload paradigm contributed to the elucidation of limbic structures and neocortical sites involved in memory workload processes. The progressive degeneration of these same structures causes the gradual decline of memory functions observed in early Alzheimer's disease. Research findings indicate that ERPs elicited by a memory workload paradigm are sensitive markers for diagnosis, treatment and clinical follow-up of early Alzheimer's patients. In addition, ERPs provide objective measurement of cholinergic medication effects on cerebral functions involved in memory processes through neuropsychophysiological parameters.     

Unmasking Myocardial Dysfunction in Patients Hospitalized for Community-Acquired Pneumonia Using a 4-Chamber 3-Dimensional Volume/Strain Analysis

Lower respiratory infection was reported as the most common fatal infectious disease. Community-acquired pneumonia (CAP) and myocardial injury are associated; yet, true prevalence of myocardial injury is probably underestimated. We assessed the rate and severity of myocardial dysfunction in patients with CAP. Admitted patients diagnosed with CAP were prospectively recruited. All the patients had C-reactive protein (CRP), brain natriuretic peptide (BNP), and high-sensitivity cardiac troponin (hs-cTnl) tests added to their routine workup. 2D/3D Doppler echocardiography was done on a Siemens Acuson SC2000 machine ≤ 24 h of diagnosis. 3D datasets were blindly analyzed for 4-chamber volumes/strains using EchobuildR 3D-Volume Analysis prototype software, v3.0 2019, Siemens-Medical Solutions. Volume/strain parameters were correlated with admission clinical and laboratory findings. The cohort included 34 patients, median age 60 years (95% CI 55–72). The cohort included 18 (53%) patients had hypertension, 9 (25%) had diabetes mellitus, 7 (21%) were smokers, 7 (21%) had previous myocardial infarction, 4 (12%) had chronic renal failure, and 1 (3%) was on hemodialysis treatment. 2D/Doppler echocardiography findings showed normal ventricular size/function (LVEF 63 ± 9%), mild LV hypertrophy (104 ± 36 g/m²), and LA enlargement (41 ± 6 mm). 3D volumes/strains suggested bi-atrial and right ventricular dysfunction (global longitudinal strain RVGLS =  − 8 ± 4%). Left ventricular strain was normal (LVGLS =  − 18 ± 5%) and correlated with BNP (r = 0.40, p = 0.024). The patients with LVGLS >  − 17% had higher admission blood pressure and lower SaO₂ (144 ± 33 vs. 121 ± 20, systolic, mmHg, p = 0.02, and 89 ± 4 vs. 94 ± 4%, p = 0.006, respectively). hs-cTnl and CRP were not different. Using novel 3D volume/strain software in CAP patients, we demonstrated diffuse global myocardial dysfunction involving several chambers. The patients with worse LV GLS had lower SaO₂ and higher blood pressure at presentation. LV GLS correlated with maximal BNP level and did not correlate with inflammation or myocardial damage markers.     

Interplay between the key proteins of serotonin system in SSRI antidepressants efficacy

Introduction: Selective serotonin reuptake inhibitors (SSRIs) are the most effective and most used antidepressant drugs. Acting by inhibiting serotonin (5-HT) transporter, SSRIs display a typical 3–4-week delay in their therapeutic effects, with nearly 40% of depressed patients remaining treatment-resistant. Recent evidence suggests complex interplay between 5-HT receptors and key proteins of 5-HT metabolism in molecular mechanisms of such delay and resistance to SSRIs.

Area covered: This paper concentrates on the interplay between 5-HT receptors in the delay of therapeutic effect of SSRIs, and the interaction between tryptophan hydroxylase 2 and 5-HT transporter in the SSRI resistance. Specifically, it discusses: (1) the data on the association between antidepressant drug efficacy and genetically defined characteristics of key proteins in the 5-HT signaling (TPH2, MAOA, SERT and 5-HT_1A receptor), (2) the effect of dimerization of 5-HT₇ and 5-HT_1A receptors on the internalization and functioning of 5-HT_1A presynaptic receptors, (3) the role of Tph2 deficiency in the resistance to SSRIs treatment. We shift the emphasis from individual proteins to their interactions in explaining antidepressant action of SSRI.

Expert opinion: These interactions should be considered when developing more effective antidepressant drugs as well as for predicting and improving the efficacy of antidepressant therapies.     

Diagnosis and surgical treatment of pathologic tortuosity of carotid and vertebral arteries

The article summarizes an experience with 179 surgical interventions on patients with pathological tortuosity of brachiocephalic arteries. The optimal described diagnostic algorithm for this pathology included ultrasonic dopplerography, transcranial dopplerography, angiography or magnetic resonance tomography in the angiography regimen. Clinical and angiographic indications to surgical treatment of this pathology were determined. The operative treatment was carried on in patients with neurological symptoms having kinks of brachiocephalic arteries. The intraoperative strategy depending on the type and localization of the disease are analyzed. Stabile regression of manifestations of vascular cerebral insufficiency after surgical correction of the pathological tortuosity of the brachiocephalic arteries was achieved in 76% of the patients.     

Palmitoylation of the 5-hydroxytryptamine4a receptor regulates receptor phosphorylation, desensitization, and beta-arrestin-mediated endocytosis

The mouse 5-hydroxytryptamine4a (5-HT4a) receptor is an unusual member of the G protein-coupled receptor superfamily because it possesses two separate carboxyl-terminal palmitoylation sites, which may allow the receptor to adopt different conformations in an agonist-dependent manner (J Biol Chem 277:2534-2546, 2002). By targeted mutation of the proximal (Cys-328/329) or distal (Cys-386) palmitoylation sites, or a combination of both, we generated 5-HT4a receptor variants with distinct functional characteristics. In this study, we showed that upon 5-HT stimulation, the 5-HT4a receptor undergoes rapid (t(1/2) approximately 2 min) and dose-dependent (EC50 approximately 180 nM) phosphorylation on serine residues by a staurosporine-insensitive receptor kinase. Overexpression of GRK2 significantly reduced the receptor-promoted cAMP formation. The Cys328/329-Ser mutant, which is constitutively active in the absence of ligand, exhibited enhanced receptor phosphorylation under both basal and agonist-stimulated conditions and was more effectively desensitized and internalized via a beta-arrestin-2 mediated pathway compared with the wild-type 5-HT4a. In contrast, G protein activation, phosphorylation, desensitization, and internalization of the other palmitoylation-deficient receptor mutants were affected differently. These findings suggest that palmitoylation plays an important role in modulating 5-HT4a receptor functions and that G protein activation, phosphorylation, desensitization, and internalization depend on the different receptor conformations.     

Flux coupling analysis of genome-scale metabolic network reconstructions

In this paper, we introduce the Flux Coupling Finder (FCF) framework for elucidating the topological and flux connectivity features of genome-scale metabolic networks. The framework is demonstrated on genome-scale metabolic reconstructions of Helicobacter pylori, Escherichia coli, and Saccharomyces cerevisiae. The analysis allows one to determine whether any two metabolic fluxes, v(1) and v(2), are (1) directionally coupled, if a non-zero flux for v(1) implies a non-zero flux for v(2) but not necessarily the reverse; (2) partially coupled, if a non-zero flux for v(1) implies a non-zero, though variable, flux for v(2) and vice versa; or (3) fully coupled, if a non-zero flux for v(1) implies not only a non-zero but also a fixed flux for v(2) and vice versa. Flux coupling analysis also enables the global identification of blocked reactions, which are all reactions incapable of carrying flux under a certain condition; equivalent knockouts, defined as the set of all possible reactions whose deletion forces the flux through a particular reaction to zero; and sets of affected reactions denoting all reactions whose fluxes are forced to zero if a particular reaction is deleted. The FCF approach thus provides a novel and versatile tool for aiding metabolic reconstructions and guiding genetic manipulations.     

Economic Consequences and Potentially Preventable Costs Related to Osteoporosis in the Netherlands

Background

Osteoporosis often does not involve symptoms, and so the actual number of patients with osteoporosis is higher than the number of diagnosed individuals. This underdiagnosis results in a treatment gap.

The use of passive hemagglutination for determining the fibronectin-binding properties of microorganisms

The authors present the data that evidence in favour of employing fibronectin sensitized formalin-treated red cells for the indication of fibronectin-binding microorganisms (as exemplified by staphylococci) in the passive hemagglutination test (PHAT). The possibility of a quantitative estimation of fibronectin binding by the PHAT is shown. PHAT will help detect higher numbers of fibronectin-binding staphylococci than flocculation on the glass.     

The passive coagglutination reaction as a method of determining the fibronectin-binding properties of microorganisms]

The authors suggest a method for the detection of S. aureus and S. epidermidis strains fibronectin-binding ability (FNBA), based on a new principle--the passive coagglutination test. Using this test, FNBA was detected at 16 of the 20 tested S. aureus strains and in 6 of the 11 S. epidermidis strains. This method yields more demonstrable results than the flake-formation test on the glass in the presence of fibronectin. A nonagglutinating fibronectin form may be used in the test.