Registration of Functioning of a Single Horseradish Peroxidase Macromolecule with a Solid-State Nanopore.

Currently, nanopore-based technology for the determination of the functional activity of single enzyme molecules continues its development. The use of natural nanopores for studying single enzyme molecules is known. At that, the approach utilizing artificial solid-state nanopores is also promising but still understudied. Herein, we demonstrate the use of a nanotechnology-based approach for the investigation of the enzymatic activity of a single molecule of horseradish peroxidase with a solid-state nanopore. The artificial 5 nm solid-state nanopore has been formed in a 40 nm thick silicon nitride structure. A single molecule of HRP has been entrapped into the nanopore. The activity of the horseradish peroxidase (HRP) enzyme molecule inserted in the nanopore has been monitored by recording the time dependence of the ion current through the nanopore in the course of the reaction of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) oxidation reaction. We have found that in the process of ABTS oxidation in the presence of 2.5 mM hydrogen peroxide, individual HRP enzyme molecules are able to retain activity for approximately 700 s before a decrease in the ion current through the nanopore, which can be explained by structural changes of the enzyme.

Neurohumoral Markers of Cardiac Autonomic Denervation after Surgical Ablation of Long-Standing Persistent Atrial Fibrillation.

Although the autonomic nervous system has an evident impact on cardiac electrophysiology and radiofrequency ablation (RFA) is the conventional technique for treating persistent atrial fibrillation, the specific effects of RFA have been insufficiently studied to date. Here, we investigated whether RFA affects neurohumoral transmitter levels and myocardial 123I-metaiodobenzylguanidine (123I-MIBG) uptake. To perform this task, we compared two groups of patients with acquired valvular heart disease: patients who had undergone surgical AF ablation and patients with sinus rhythm. The decrease in norepinephrine (NE) level in the coronary sinus had a direct association with the heart-to-mediastinum ratio (p = 0.02) and a negative correlation with 123I-MIBG uptake defects (p = 0.01). The NE level decreased significantly after the main surgery, both in patients with AF (p = 0.0098) and sinus rhythm (p = 0.0039). Furthermore, the intraoperative difference between the norepinephrine levels in the ascending aorta and coronary sinus (ΔNE) of -400 pg/mL was determined as a cut-off value to evaluate RFA efficacy, as denervation failed in all patients with ΔNE < -400 pg/mL. Hence, ΔNE can be utilized to predict the efficacy of the "MAZE-IV" procedure and to assess the risk of AF recurrence after RFA.

Femtosecond Laser-Printed Gold Nanoantennas for Electrically Driven and Bias-Tuned Nanoscale Light Sources Operating in Visible and Infrared Spectral Ranges.

Nanoscale electrically driven light-emitting sources with tunable wavelength represent a milestone for implementation of integrated optoelectronic chips. Plasmonic nanoantennas exhibiting an enhanced local density of optical states (LDOS) and strong Purcell effect hold promise for fabrication of bright nanoscale light emitters. Here, we justify gold parabola-shaped nanobumps and their ordered arrays produced by direct ablation-free femtosecond laser printing as broadband plasmonic light sources electrically excited by a probe of scanning tunneling microscope (STM). I-V curves of the probe-nanoantenna tunnel junction reveal characteristic bias voltages correlating with visible-range localized (0.55 and 0.85 µm) and near-IR (1.65 and 1.87 µm) collective plasmonic modes of these nanoantennas. These multiband resonances confirmed by optical spectroscopy and full-wave simulations provide enhanced LDOS for efficient electrically driven and bias-tuned light emission. Additionally, our studies confirm remarkable applicability of STM for accurate study of optical modes supported by the plasmonic nanoantennas at nanoscale spatial resolution.

Nanoscale Electrically Driven Light Source Based on Hybrid Semiconductor/Metal Nanoantenna.

A micro- or nanosized electrically controlled source of optical radiation is one of the key elements in optoelectronic systems. The phenomenon of light emission via inelastic tunneling (LEIT) of electrons through potential barriers or junctions opens up new possibilities for development of such sources. In this work, we present a simple approach for fabrication of nanoscale electrically driven light sources based on LEIT. We employ STM lithography to locally modify the surface of a Si/Au film stack via heating, which is enabled by a high-density tunnel current. Using the proposed technique, hybrid Si/Au nanoantennas with a minimum diameter of 60 nm were formed. Studying both electronic and optical properties of the obtained nanoantennas, we confirm that the resulting structures can efficiently emit photons in the visible range because of inelastic scattering of electrons. The proposed approach allows for fabrication of nanosized hybrid nanoantennas and studying their properties using STM.

Vitamin D Status and Immune Response in Hospitalized Patients with Moderate and Severe COVID-19.

A low 25-hydroxyvitamin D (25(OH)D) level is considered as an independent risk factor for COVID-19 severity. However, the association between vitamin D status and outcomes in COVID-19 is controversial. In the present study we investigate the association between the serum 25(OH)D level, immune response, and clinical disease course in patients with COVID-19. A total of 311 patients hospitalized with COVID-19 were enrolled. For patients with a vitamin D deficiency/insufficiency, the prevalence of severe COVID-19 was higher than in those with a normal 25(OH)D level (p < 0.001). The threshold of 25(OH)D level associated with mortality was 11.4 ng/mL (p = 0.003, ROC analysis). The frequency of CD3+CD4+ T helper (Th) cells was decreased in patients with 25(OH)D level ≤ 11.4 ng/mL, compared to healthy controls (HCs). There were no differences in the frequency of naive, central memory (CM), effector memory (EM), and terminally differentiated effector memory Th cells in patients with COVID-19 compared to HCs. The frequency of T-follicular helpers was decreased both in patients with 25(OH)D level > 11.4 ng/mL (p < 0.001) and 25(OH)D level ≤ 11.4 ng/mL (p = 0.003) compared to HCs. Patients with 25(OH)D level > 11.4 ng/mL had an increased frequency of Th2 CM (p = 0.010) and decreased Th17 CM (p < 0.001). While the frequency of Th2 EM was significantly increased, the frequency of Th17 EM was significantly decreased in both groups compared to HCs. Thus, 25(OH)D level is an independent risk factor for the disease severity and mortality in patients with COVID-19. We demonstrate that the serum 25(OH)D level ≤ 11.4 ng/mL is associated with the stimulation of Th2 and the downregulation of Th17 cell polarization of the adaptive immunity in patients with COVID-19.

Association between Markers of Fibrosis and Heart Failure Incidence in Patients with Type 2 Diabetes Mellitus.

Type 2 diabetes mellitus (T2DM) and chronic heart failure (HF) have close association, and several biomarkers have been studied to better understand this association and improve prediction of HF in T2DM. Furthermore, in recent clinical trials, sodium glucose cotransporter 2 inhibitors (SGLT2i), glucose-lowering drugs, improved HF outcomes. The objective of the present study was to evaluate association between circulating biomarkers of fibrosis and incidence of HF with preserved ejection fraction (HFpEF) in patients with T2DM receiving sodium glucose cotransporter 2 inhibitors (SGLT2i). Materials and Methods. At baseline, transthoracic echocardiography and laboratory assessment of N-terminal fragment of the brain natriuretic peptide (Nt-proBNP), soluble suppression of tumorigenesis-2 (sST2), galectin-3 (Gal-3), C-terminal propeptide of procollagen type I (PICP), N-terminal propeptide of procollagen type III (PIIINP), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of matrix proteinase-1 (TIMP-1) were done. After 3 years of follow-up, information about HF events (hospitalization for HF, established HF in outpatient department by a cardiologist) was obtained. Results. Seventy-two patients were included in the study. The mean age was 57 (49.7; 63.2) years; 44% were female. Most patients had T2DM for more than 4 years. All patients were overweight or had obesity, and 93% patients had arterial hypertension (AH). After 3 years of follow-up, HFpEF was established in 21% patients. Patients were divided into two groups according to the presence of HFpEF, and baseline characteristics were compared. Patients with HF were older and had longer diabetes and AH duration and higher Nt-proBNP, Gal-3, PIIINP, and PICP levels at baseline than patients without HF (all p < 0.05). Gal - 3 > 10 ng/ml (OR = 2.25; 95% CI, 1.88-5.66; p = 0.01) and NT - pro - BNP > 80 pg/ml (OR = 2.64; 95% CI, 1.56-4.44; p = 0.001) were associated with increased risk of HF incidence. Age > 60 years, diabetes duration > 10 years, and presence of abdominal obesity were independent predictors of HFpEF as well. Conclusions. T2DM patients treated with SLGT2i, who developed HFpEF after 3 years of follow-up, had higher PICP, PIIINP, Gal-3, and NT-proBNP serum concentrations at baseline, and Gal-3 level was an independent predictor of HFpEF.

Clinical phenotypes of primary hyperparathyroidism in hospitalized patients who underwent parathyroidectomy.

OBJECTIVE: The aim of our study was to investigate the distribution of the PHPT clinical manifestations and biochemical features in patients who underwent parathyroidectomy. MATERIALS AND METHODS: Medical records of 449 patients from three Medical Centers (Saint-Petersburg, Russia), hospitalized during a period from 2011 to 2018, were reviewed. History and anthropometric data, laboratory results (iPTH, total and iCa, phosphorus, ALP, 24-h urinary calcium, 25(OH)D) and imaging data (ultrasonography, scintigraphy, CT/MRI scan, DXA) were analyzed. RESULTS: Three hundred ninety-four patients were included in the final analysis. Median age was 60 years with 94.2% being women. Symptomatic disease was evident in 222 (56.4%) patients, asymptomatic in 172 (43.6%). Skeletal involvement was more common for women, while frequency of other manifestations did not differ in both genders. There was no difference between symptomatic and asymptomatic patients in age. Serum iPTH level was higher in symptomatic patients (202.9 and 181.0 pg/mL, P = 0.022). Serum 25(OH)D level was estimated in few patients and negatively correlated with PTH (r = ¯0.294, P = 0.005), iCa (r = ¯0.268, P = 0.010) and total Ca (r = ¯0.284, P = 0.014) levels. Manifestations of CVD were observed in 67.7% of cases and affected equally both symptomatic and asymptomatic patients (70.7 and 63.4%, P = 0.076). Both age and BMI were higher in patients with CVD, whether or not they were symptomatic (62 and 53 years, P < 0.0001; 30.4 vs 26.0 kg/m2, P < 0.0001, respectively). CONCLUSIONS: This experience illustrates that symptomatic phenotype is still the most common form of PHPT.

Scanning Tunneling Microscopy-Induced Light Emission and I(V) Study of Optical Near-Field Properties of Single Plasmonic Nanoantennas.

Electrically driven plasmonic nanoantennas can be integrated as a local source of the optical signal of advanced photonic schemes for on-chip data processing. The inelastic electron tunneling provides the photon generation or launch of surface plasmon waves. This process can be enhanced by the local density of optical states of nanoantennas. In this paper, we used scanning tunnel microscopy-induced light emission to probe the local optoelectronic properties of single gold nanodiscs. The electromagnetic field distribution in the vicinity of plasmonic structures was investigated with high spatial resolution. The obtained photon maps reveal the nonuniform distribution of electromagnetic near-fields, which is consistent with nanoantenna optical modes. Also, the analysis of derived I(V) curves showed a direct correlation between the nanoantenna optical states and the appearance of features on current-voltage characteristics.

Glass/Au Composite Membranes with Gold Nanoparticles Synthesized inside Pores for Selective Ion Transport.

Nanocomposite membranes have been actively developed in the last decade. The involvement of nanostructures can improve the permeability, selectivity, and anti-fouling properties of a membrane for improved filtration processes. In this work, we propose a novel type of ion-selective Glass/Au composite membrane based on porous glass (PG), which combines the advantages of porous media and promising selective properties. The latter are achieved by depositing gold nanoparticles into the membrane pores by the laser-induced liquid phase chemical deposition technique. Inside the pores, gold nanoparticles with an average diameter 25 nm were formed, which was confirmed by optical and microscopic studies. To study the transport and selective properties of the PG/Au composite membrane, the potentiometric method was applied. The uniform potential model was used to determine the surface charge from the experimental data. It was found that the formation of gold nanoparticles inside membrane pores leads to an increase in the surface charge from -2.75 mC/m2 to -5.42 mC/m2. The methods proposed in this work allow the creation of a whole family of composite materials based on porous glasses. In this case, conceptually, the synthesis of these materials will differ only in the selection of initial precursors.

Mental state, psychoemotional status, quality of life and treatment compliance in patients with Type 2 diabetes mellitus.

AIM: To identify correlations between quality of life (QoL), emotional and mental state in patients with Type 2 diabetes mellitus (T2DM) and to evaluate its contribution in prediction of compliance. MATERIALS & METHODS: The T2DM patients aged 18-75 years with at least 12 weeks of stable hypoglycemic therapy were included to this cross-sectional study. We used Mini Mental State Examination (MMSE) for mental state assessment, Hospital Anxiety and Depression Scale (HADS) for anxiety and depression level and EQ-5D for QoL. Compliance level was self-reported by patients. RESULTS: The QoL positively correlates with MMSE score (p < 0.0001) and negatively with HADS anxiety (p < 0.0001) and depression (p < 0.0001) levels. The MMSE score is higher (p < 0.0001), and both HADS levels are lower (p < 0.01) in patients with higher compliance level. CONCLUSION: Cognitive function and psychoemotional state in T2DM patients are important for treatment compliance and QoL and are to be corrected whenever possible.

Effects of glucagon-like peptide 1 analogs in combination with insulin on myocardial infarct size in rats with type 2 diabetes mellitus.

AIM: To evaluate the effects of glucagon-like peptide-1 analogs (GLP-1a) combined with insulin on myocardial ischemia-reperfusion injury in diabetic rats. METHODS: Type 2 diabetes mellitus (T2DM) was induced in male Wistar rats with streptozotocin (65 mg/kg) and verified using an oral glucose tolerance test. After anesthesia, the left coronary artery was occluded for 40 min followed by 80 min reperfusion. Blood glucose level was measured during surgery. Rats were randomized into six groups as follows: (1) control rats; (2) insulin (0.1 U/kg) treated rats prior to ischemia; (3) insulin (0.1 U/kg) treated rats at reperfusion; (4) GLP-1a (140 mg/kg) treated rats prior to ischemia; (5) GLP-1a (140 mg/kg) treated rats at reperfusion; and (6) rats treated with GLP-1a (140 mg/kg) prior to ischemia plus insulin (0.1 U/kg) at reperfusion. Myocardial area at risk and infarct size was measured planimetrically using Evans blue and triphenyltetrazolium chloride staining, respectively. RESULTS: There was no significant difference in the myocardial area at risk among groups. Insulin treatment before ischemia resulted in a significant increase in infarct size (34.7% ± 3.4% vs 18.6% ± 3.1% in the control rats, P < 0.05). Post-ischemic administration of insulin or GLP-1a had no effect on infarct size. However, pre-ischemic administration of GLP-1a reduced infarct size to 12% ± 2.2% (P < 0.05). The maximal infarct size reduction was observed in the group treated with GLP-1a prior to ischemia and insulin at reperfusion (8% ± 1.6%, P < 0.05 vs the control and GLP-1a alone treated groups). CONCLUSION: GLP-1a pre-administration results in myocardial infarct size reduction in rats with T2DM. These effects are maximal in rats treated with GLP-1a pre-ischemia plus insulin at reperfusion.

Presenilin1/γ-secretase protects neurons from glucose deprivation-induced death by regulating miR-212 and PEA15.

Reduced cerebral glucose utilization is found in aged individuals and often is an early sign of neurodegeneration. Here, we show that under glucose deprivation (GD) conditions, decreased expression of presenilin 1 (PS1) results in decreased neuronal survival, whereas increased PS1 increases neuronal survival. Inhibition of γ-secretase also decreases neuronal survival under GD conditions, which suggests the PS1/γ-secretase system protects neurons from GD-induced death. We also show that neuronal levels of the survival protein, phosphoprotein enriched in astrocytes at ∼15 kDa (PEA15), and its mRNA are regulated by PS1/γ-secretase. Furthermore, down-regulation of PEA15 decreases neuronal survival under reduced glucose conditions, whereas exogenous PEA15 increases neuronal survival even in the absence of PS1, which indicates that PEA15 promotes neuronal survival under GD conditions. The absence or reduction of PS1, as well as γ-secretase inhibitors, increases neuronal miR-212, which targets PEA15 mRNA. PS1/γ-secretase activates the transcription factor, cAMP response element-binding protein, regulating miR-212, which targets PEA15 mRNA. Taken together, our data show that under conditions of reduced glucose, the PS1/γ-secretase system decreases neuronal losses by suppressing miR-212 and increasing its target survival factor, PEA15. These observations have implications for mechanisms of neuronal death under conditions of reduced glucose and may provide targets for intervention in neurodegenerative disorders.-Huang, Q., Voloudakis, G., Ren, Y., Yoon, Y., Zhang, E., Kajiwara, Y., Shao, Z., Xuan, Z., Lebedev, D., Georgakopoulos, A., Robakis, N. K. Presenilin1/γ-secretase protects neurons from glucose deprivation-induced death by regulating miR-212 and PEA15.

Perfusion and metabolic scintigraphy with (123)I-BMIPP in prognosis of cardiac resynchronization therapy in patients with dilated cardiomyopathy.

OBJECTIVE: The objective of the study was to investigate the left ventricular (LV) myocardial perfusion and metabolism in patients with idiopathic dilated cardiomyopathy (DCM) and to identify the scintigraphic predictors of the efficacy of cardiac resynchronization therapy (CRT). METHODS: The study comprised 63 patients with DCM and severe heart failure (NYHA class III-IV). Before CRT, all patients received gamma-scintigraphy with (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) and with (123)I-ß-methyl-iodophenyl pentadecanoic acid ((123)I-BMIPP) for evaluation of myocardial perfusion and metabolism, respectively. Before and after 6 months of CRT, all patients underwent echocardiography study to assess cardiac hemodynamics. RESULTS: After 6 months of CRT, patients were divided into two groups: group 1 comprised responders in whom LV end systolic volume (LVESV) decreased by ≥15 % (n = 39); group 2 comprised non-responders in whom LVESV decreased by <15 % (n = 24). Before CRT, LV pumping function did not significantly differ between groups. Significant differences were found in the following preoperative scintigraphic parameters: myocardial perfusion defect size [7.4 % (5.9; 13.2) % and 11.8 (8.8; 16.2) %, p < 0.05] and metabolic defect size [7.4 (4.4; 14.7) % and 8.8 (8.8; 17.6) %, p < 0.05]. Metabolic scintigraphy showed greater diagnostic efficacy in determining the indications for CRT compared with perfusion scintigraphy [areas under the ROC curves (AUC) of 0.722 and 0.612, respectively]. The best metabolic defect size threshold value of 7.35 % predicted CRT efficacy with the sensitivity and specificity rates of 77.8 and 66.7 %, respectively. CONCLUSION: Data of metabolic scintigraphy may be useful for the integrated prediction of CRT efficacy.

The possible role of nuclear imaging in assessment of the cardiac resynchronization therapy effectiveness in patients with moderate heart failure.

BACKGROUND: The aim of the study was to elucidate the role of nuclear medicine imaging in the selection of candidates for cardiac resynchronization therapy (CRT) and in the evaluation of CRT effectiveness METHODS: We studied 28 patients (19 male and 9 female) with dilated cardiomyopathy (DCM) and heart failure (HF). Before implantation of CRT device, all patients underwent SPECT with (99m)Tc-MIBI at rest to evaluate the myocardial perfusion, (123)I-BMIPP to evaluate the myocardial metabolism, and gated cardiac blood-pool SPECT (GBPS) to assess the myocardial contractile function. Following CRT, all patients were examined with 99mTc-MIBI SPECT and GBPS 12 ± 3 months after the intervention. RESULTS: All patients after CRT were divided into three groups. The first group included 10 patients with LVEF increased by more than 10 % (hyperresponders), the 2nd group included 11 patients with an increase in EF of more than 5 % but less than 10 % (responders) and third group consisted of 7 males whose LVEF remained unchanged or worsened compared with pre-operative values (nonresponders). Prior to CRT, no statistically significant differences were found between groups in hemodynamic parameters (EF, EDV, ESV, SV), intra- and interventricular dyssynchrony, as well as in the midsize of perfusion defects. Following long-term CRT, we found increase in LVEF and decrease in average size of perfusion defects in groups of hyperresponders and responders (p < 0.05). Results of SPECT with (123)I-BMIPP, performed prior to CRT, showed that nonresponders had more pronounced disturbance of myocardial metabolism compared with the group of hyperresponders (20 vs. 14.7 %, p < 0.05). CONCLUSION: The radionuclide methods can be used as possible indicators in the evaluation effectiveness and selection of candidates on the CRT.

Behavioral perseveration and impairment of long-term memory in rats after intrahippocampal injection of kainic acid in subconvulsive dose.

Delayed disturbances of cognitive functions caused by intrahippocampal injection of subconvulsive dose of kainic acid were studied in rats. Animals were behaviorally tested for the presence of cognitive deterioration 1 week after bilateral injection of 0.25 microg kainic acid into the left and right hippocampi. Behavioral tests included the retrieval of a food-procuring task, its experimental extinction, and learning of a new similar task. Kainate-treated rats showed deterioration of performance of the task learned before the treatment: An impairment of the task performance occurred in the first trial of a daily session (each daily session consisted of 10 trials), and beginning from the second trial, the task was performed as rapidly as by control animals. This deterioration of retrieval in the first trial took place during several days, in spite of daily training during the retrieval test. Other disturbances of cognitive functions in kainate-treated rats were revealed in the test of experimental extinction of the response. At the initial step of this test, the rats showed active behavioral perseveration, performing habitual response with short latencies in spite of reinforcement removal. Besides, kainate-treated rats made significantly more responses before full extinction (inhibition of the previously learned response) than the control rats. In the learning test, kainate-treated rats did not exhibit any disturbances: repeated learning was the same as in the control group. Therefore, results showed that hippocampal dysfunctions induced by kainic acid resulted in the following cognitive disturbances: difficulties in memory retrieval and weakening of inhibitory control. These disturbances can be most adequately explained on the basis of the concept, according to which the hippocampus acts as a detector and comparator of new signals, thereby accomplishing selective attention.