Radiolabeling of Platelets with 99mTc-HYNIC-Duramycin for In Vivo Imaging Studies

Following the in vivo biodistribution of platelets can contribute to a better understanding of their physiological and pathological roles, and nuclear imaging methods, such as single photon emission tomography (SPECT), provide an excellent method for that. SPECT imaging needs stable labeling of the platelets with a radioisotope. In this study, we report a new method to label platelets with 99mTc, the most frequently used isotope for SPECT in clinical applications. The proposed radiolabeling procedure uses a membrane-binding peptide, duramycin. Our results show that duramycin does not cause significant platelet activation, and radiolabeling can be carried out with a procedure utilizing a simple labeling step followed by a size-exclusion chromatography-based purification step. The in vivo application of the radiolabeled human platelets in mice yielded quantitative biodistribution images of the spleen and liver and no accumulation in the lungs. The performed small-animal SPECT/CT in vivo imaging investigations revealed good in vivo stability of the labeling, which paves the way for further applications of 99mTc-labeled-Duramycin in platelet imaging.

Results of a systematic review and meta-analysis of early studies on ivermectin in SARS-CoV-2 infection

Ivermectin, an antiparasitic drug, has been repurposed for COVID-19 treatment during the SARS-CoV-2 pandemic. Although its antiviral efficacy was confirmed early in vitro and in preclinical studies, its clinical efficacy remained ambiguous. Our purpose was to assess the efficacy of ivermectin in terms of time to viral clearance based on the meta-analysis of available clinical trials at the closing date of the data search period, one year after the start of the pandemic. This meta-analysis was reported by following the PRISMA guidelines and by using the PICO format for formulating the question. The study protocol was registered on PROSPERO. Embase, MEDLINE (via PubMed), Cochrane Central Register of Controlled Trials (CENTRAL), bioRvix, and medRvix were searched for human studies of patients receiving ivermectin therapy with control groups. No language or publication status restrictions were applied. The search ended on 1/31/2021 exactly one year after WHO declared the public health emergency on novel coronavirus. The meta-analysis of three trials involving 382 patients revealed that the mean time to viral clearance was 5.74 days shorter in case of ivermectin treatment compared to the control groups [WMD = -5.74, 95% CI (-11.1, -0.39), p = 0.036]. Ivermectin has significantly reduced the time to viral clearance in mild to moderate COVID-19 diseases compared to control groups. However, more eligible studies are needed for analysis to increase the quality of evidence of ivermectin use in COVID-19.

In Vitro Determination of Inhibitory Effects of Humic Substances Complexing Zn and Se on SARS-CoV-2 Virus Replication

(1) Background: Humic substances are well-known human nutritional supplement materials and they play an important performance-enhancing role as animal feed additives. For decades, ingredients of humic substances have been proven to carry potent antiviral effects against different viruses. (2) Methods: Here, the antiviral activity of a humic substance containing ascorbic acid, Se- and Zn2+ ions intended as a nutritional supplement material was investigated against SARS-CoV-2 virus B1.1.7 Variant of Concern ("Alpha Variant") in a VeroE6 cell line. (3) Results: This combination has a significant in vitro antiviral effect at a very low concentration range of its intended active ingredients. (4) Conclusions: Even picomolar concentration ranges of humic substances, Vitamin C and Zn/Se ions in the given composition, were enough to achieve 50% viral replication inhibition in the applied SARS-CoV-2 virus inhibition test.

Thermoresponsive Poly(N,N-diethylacrylamide-co-glycidyl methacrylate) Copolymers and Its Catalytically Active α-Chymotrypsin Bioconjugate with Enhanced Enzyme Stability

Responsive (smart, intelligent, adaptive) polymers have been widely explored for a variety of advanced applications in recent years. The thermoresponsive poly(N,N-diethylacrylamide) (PDEAAm), which has a better biocompatibility than the widely investigated poly(N,N-isopropylacrylamide), has gained increased interest in recent years. In this paper, the successful synthesis, characterization, and bioconjugation of a novel thermoresponsive copolymer, poly(N,N-diethylacrylamide-co-glycidyl methacrylate) (P(DEAAm-co-GMA)), obtained by free radical copolymerization with various comonomer contents and monomer/initiator ratios are reported. It was found that all the investigated copolymers possess LCST-type thermoresponsive behavior with small extent of hysteresis, and the critical solution temperatures (CST), i.e., the cloud and clearing points, decrease linearly with increasing GMA content of these copolymers. The P(DEAAm-co-GMA) copolymer with pendant epoxy groups was found to conjugate efficiently with α-chymotrypsin in a direct, one-step reaction, leading to enzyme-polymer nanoparticle (EPNP) with average size of 56.9 nm. This EPNP also shows reversible thermoresponsive behavior with somewhat higher critical solution temperature than that of the unreacted P(DEAAm-co-GMA). Although the catalytic activity of the enzyme-polymer nanoconjugate is lower than that of the native enzyme, the results of the enzyme activity investigations prove that the pH and thermal stability of the enzyme is significantly enhanced by conjugation the with P(DEAAm-co-GMA) copolymer.

The Need for Accurate Osmotic Pressure and Mass Transfer Resistances in Modeling Osmotically Driven Membrane Processes

The widely used van 't Hoff linear relation for predicting the osmotic pressure of NaCl solutions may result in errors in the evaluation of key system parameters, which depend on osmotic pressure, in pressure-retarded osmosis and forward osmosis. In this paper, the linear van 't Hoff approach is compared to the solutions using OLI Stream Analyzer, which gives the real osmotic pressure values. Various dilutions of NaCl solutions, including the lower solute concentrations typical of river water, are considered. Our results indicate that the disparity in the predicted osmotic pressure of the two considered methods can reach 30%, depending on the solute concentration, while that in the predicted power density can exceed over 50%. New experimental results are obtained for NanoH2O and Porifera membranes, and theoretical equations are also developed. Results show that discrepancies arise when using the van 't Hoff equation, compared to the OLI method. At higher NaCl concentrations (C > 1.5 M), the deviation between the linear approach and the real values increases gradually, likely indicative of a larger error in van 't Hoff predictions. The difference in structural parameter values predicted by the two evaluation methods is also significant; it can exceed the typical 50-70% range, depending on the operating conditions. We find that the external mass transfer coefficients should be considered in the evaluation of the structural parameter in order to avoid overestimating its value. Consequently, measured water flux and predicted structural parameter values from our own and literature measurements are recalculated with the OLI software to account for external mass transfer coefficients.

Examination of left ventricular contractile reserve by Doppler myocardial imaging in patients with dilated cardiomyopathy

Detection of left ventricular contractile reserve by means of dobutamine stress echocardiography is a well known technique. The aim of the present study was to detect velocity changes during the administration of dobutamine, to establish if Doppler myocardial imaging is a suitable method for determining left ventricular contractile reserve, and to determine if the technique provides more information than traditional stress echocardiography. Twenty-five patients (all males; mean age, 53.4 years) were examined for a clinical diagnosis of idiopathic dilated cardiomyopathy with a poor left ventricular systolic function (ejection fraction less than 30%). Doses of 5-10 and 20 mg/kg/min dobutamine were administered and elevated at 4-minute intervals. Ejection fraction was calculated using the Simpson rule. The peak systolic and the early and late diastolic velocities were measured in the basal segment of the septum and the inferior wall at baseline and at full dose of dobutamine. Results indicated that peak systolic velocity increased significantly, both in the septum (0.11±0.03 vs. 0.20±0.05 m/sec; p=0.001) and in the inferior wall (0.10±0.05 vs. 0.17±0.06 m/sec; p=0.03). Late diastolic velocities also increased significantly, both in the septum (0.17±0.05 vs. 0.22±0.07 m/sec; p=0.01) and in the inferior wall (0.18±0.08 vs.0.21±0.02 m/sec; p=0.01). There was a significant linear correlation between the relative increases in basal ejection fraction value and in peak systolic velocity upon dobutamine stimulation. Patients were divided into responders and nonresponders based on responses in either ejection fraction (25% relative increase) or peak systolic velocity (5 cm/s increase). This study concludes that 1) Doppler myocardial imaging is an adequate and simple technique to examine left ventricular contractile reserve; and 2) measurement of peak systolic velocity during dobutamine stimulation seems to be a simple and good indicator of left ventricular contractile reserve. (c)2001 CHF, Inc.

[Prediction of the result of high-risk coronary bypass surgery by positron emission tomography]

Coronary angiography revealed three-vessel disease in a 56-year-old male with two previous myocardial infarctions. Coronary bypass surgery was initially ruled out by cardiac surgeon because of the poor left ventricular function (EF: 23%), despite moderate viability signs during conventional isotope techniques. Positron emission tomography with 18FDG indicated a large periinfarction area of hibernating myocardium. Accordingly, coronary bypass grafting was performed. Postoperatively, the symptoms disappeared, the left ventricular wall motion abnormalities (with the exception of the scarred region demonstrated by PET) improved, and the global left ventricular function increased significantly. This case and the role of cardiac PET study for prediction of the result of revascularization are discussed.

Myocardial gallium-67 citrate scintigraphy in patients with systemic sclerosis

OBJECTIVE

To detect myocardial involvement in 16 patients with systemic sclerosis using radiogallium scintigraphy

METHODS

Sixteen patients with systemic sclerosis were investigated by myocardial gallium-67 citrate scintigraphy. Echocardiographic studies and (in the positive cases) magnetic resonance imaging were also performed.

RESULTS

Increased myocardial gallium uptake was found in five of the 16 patients. None of these positive cases exhibited any 'classical' clinical, electrocardiographic or laboratory signs characteristic of myocarditis. The mean age of the positive cases was 60.8 (SD 5.0) years compared with 44.6 (10.7) years for the negative cases; no difference was detected in the mean disease duration between these two groups. Two of the affected cases belonged to the limited scleroderma subgroup.

CONCLUSIONS

In spite of the low number of patients investigated, it is tempting to speculate that elderly patients with a disease onset around 60 years tend to be the candidates in whom a positive gallium-67 scintigraphy test may best indicate a silent myocardial interstitial inflammation.

Left ventricular wall motion abnormalities in 80 patients with systemic sclerosis

Segmental analysis of left ventricular wall motion was performed in 80 patients with systemic sclerosis by echocardiography. Half of the cases showed normal wall motion. Eighteen of the 57 patients with limited cutaneous systemic sclerosis (31.6%) exhibited hypokinetic wall motion abnormalities, while five of the 23 cases with diffuse cutaneous systemic sclerosis (21.7%) had similar findings. The three cases showing akinesis also belonged to the limited scleroderma subgroup. Our findings show that hypokinetic wall motion abnormalities can be detected in a remarkably high proportion of cases with limited cutaneous systemic sclerosis.

[Ischemic cerebrovascular lesion caused by left atrial myxoma]

A case presentation is given of a 40 years old woman with acute ischemic cerebrovascular lesion in the territory of the left middle cerebral artery caused by embolization from a myxoma in the left atrium. The tumor was diagnosed by transthoracic echocardiography. Histological examination after cardiac surgery revealed a benignant myxoma. In the six-month-long postoperative follow up gradual improvement of the neurological signs was observed. The most important morphological and clinical characteristics of myxomas are summarized. The necessity of detailed cardiological examination of each young patient with stroke is emphasized.

Left ventricular wall thickness and disease duration in systemic sclerosis

Myocardial thickness, left ventricular functions, and right heart overloading were investigated in 80 patients with systemic sclerosis by echocardiography. Based on the left ventricular wall thickness, three groups were formed. Fifteen patients with asymmetrical left ventricular wall hypertrophy (Group 1) showed shorter mean disease duration with marked diastolic and mild systolic left ventricular functional impairment. The 25 patients with wall thinning (Group 3) had a slight increase in left ventricular diameters, impaired systolic functions and longer disease duration. Group 2 with wall thickness exhibited mixed changes. Patients with increased wall thickness tended to have a shorter disease duration than patients with wall thinning. Patients with systemic sclerosis showed systolic and diastolic function impairment as compared to the 18 control healthy individuals. Pericardial disease was found in 23 cases (28.7%).

[Late post-infarction angina]

The authors survey the clinical features and therapeutic results of 88 patients suffering from late postinfarctional angina. The results of the bicycle ergometer ECG tests were negative only in the case of 8 patients. Exercise-induced silent myocardial ischaemia was registered in 45.4%. Coronary angiography revealed that 54 (61%) of the patients suffered from multivessel disease. Coronary bypass surgery was carried out in 56.8% and the rate of peripheral anastomoses was 3.1/patient. The authors consider it to be essential to detect the ischaemia in the infarct survivors with chest pain. Taking into consideration the clinical feature and the results of exercise tests, the authors propose cardiac catheterization. Myocardial revascularization is recommended if the medical therapy is not successful or the patients suffered from left main, triple-vessels disease and the myocardium is jeopardized to a large extend.

Metabolism and pharmacokinetics of dibromodulcitol (DBD, NSC-104800) in man--II. pharmacokinetics of DBD

Dibromodulcitol (DBD), labelled with [3H] at position C-1, was administered orally to 6 patients in a single dose of 15 mg/kg. Kinetic parameters were calculated for the effective drug (DBD + BrEpG + DAG), protein-bound hexitol moieties and free metabolites. Approximate values were estimated for the oral bioavailability of DBD. Disposal of the drug by metabolism and excretion was described by a simplified catenary model. The results indicated that 8-20% of the drug became firmly bound to macromolecules, probably by alkylation. The slow rate of alkylation in vivo (half-life 14 hr) may imply conversion of DBD into epoxides and their alkylating interaction with the target nucleophiles. The long retention of the firmly bound hexitol moieties in the body may be an indicator of the cumulative potency of DBD and must be taken into consideration by developing dosage schedules.