Effect of pH variation on cross-linking of water-soluble and acid-soluble chitosan with sodium tripolyphosphate and gallium-67

Background: Chitosan is a cationic biopolymer obtained from deacetylating chitin, a naturally compoundpresent in crustacean shell, fungi and exoskeleton of insects. Chitosan has various applications including drug and gene delivery systems, wound dressing and as scaffolds for tissue engineering, agriculture, textile, food and feed nanotechnology, waste water treatments. chitosan-TPP particle figure out as the most important and stable nanoparticle for chitosan application in various fields. Objective: At this study chitosan was chemically modified by sodium tripolyphosphate (TPP). Afterward, TPP-chitosan was radiolabeled with gallium-67 radionuclide. The effect of several factors on labeling yield such as chitosan solubility, acidity and concentration of TPP-chitosansolution, incubation time with gallium-67 were investigated. Methods: To prepare [67Ga] gallium-chitosan complex, chitosan (0.5 ml) was dissolved in 2.2 mCi of [67Ga] gallium chloride solution. The obtained solution was stirred for 5 min and then was kept for 30 min at room temperature. Radiochemical purity and radiolabeling yield was measured via radiochromatography that it was performed by using a radio thin-layer chromatography (TLC) scanner instrument. To investigate the effect of chitosan kind and concentration on the labeling yield, two kinds of chitosan (acid-soluble chitosan and water-soluble chitosan) with two different concentrations (1% and 0.5%) at different pH were used. In addition, labeling efficiency and stability of the 67Ga-TPP-chitosan complex (acidic/water soluble chitosan) at both concentrations (0.5 and 1%) at room temperature was assessed for 30, 45 and 60 min. Results: The incubation time has not significant effect on labeling yield. The acidic soluble chitosan, which has highest radiolabeling yield at pH=9.3-10.4, water soluble chitosan showed the highest radiolabeling yields at pH > 5. Also, the prepared complex was stable in the final solution at room temperature and can even be used 24 hours after preparation for further application. Conclusion: Taken together, the TPP modified water soluble chitosan at concentration 0.5 % depicted the highest radiochemical yield (>95 %) at the optimized condition (pH= 6.2–7.6). Therefore, TPP modified water soluble chitosan can be an effective carrier for therapeutic radionuclides for tumor treatment.

Rheumatic Myocarditis: A Poorly Recognized Etiology of Left Ventricular Dysfunction in Valvular Heart Disease Patients

Background: Heart failure occurs in ~10% of patients with acute rheumatic fever (RF), and several studies have shown that cardiac decompensation in RF results primarily from valvular disease and is not due to primary myocarditis. However, the literature on this topic is scarce, and a recent case series has shown that recurrent RF can cause ventricular dysfunction even in the absence of valvular heart disease.Methods: The present study evaluated the clinical, laboratory and imaging characteristics of 25 consecutive patients with a clinical diagnosis of myocarditis confirmed by 18F-FDG PET/CT or gallium-67 cardiac scintigraphy and RF reactivation according to the revised Jones Criteria. Patients underwent three sequential echocardiograms at (1) baseline, (2) during myocarditis and (3) post corticosteroid treatment. Patients were divided according to the presence (Group 1) or absence (Group 2) of reduced left ventricular ejection fraction (LVEF) during myocarditis episodes.Results: The median age was 42 (17–51) years, 64% of patients were older than 40 years, and 64% were women. Between Group 1 (n = 16) and in Group 2 (n = 9), there were no demographic, echocardiographic or laboratory differences except for NYHA III/IV heart failure (Group 1: 100.0% vs. Group 2: 50.0%; p = 0.012) and LVEF (30 [25–37] vs. 56 [49–62]%, respectively; p < 0.001), as expected. Group 1 patients showed a significant reduction in LVEF during carditis with further improvement after treatment. There was no correlation between LVEF and valvular dysfunction during myocarditis. Among all patients, 19 (76%) underwent 18F-FDG PET/CT, with a positive scan in 68.4%, and 21 (84%) underwent gallium-67 cardiac scintigraphy, with positive uptake in 95.2%, there was no difference between these groups.Conclusion: Myocarditis due to rheumatic fever reactivation can cause left ventricular dysfunction despite valvular disease, and it is reversible after corticosteroid treatment.

RetroSPECT: Gallium-67 As A Theranostic Imaging Agent

Gallium-67 has been in use in nuclear medicine for over 50 years. However, the tremendous interest in gallium imaging in theranostics in recent times has focused on the PET radionuclide gallium-68. In this article it is suggested that the longer-lived gallium-67, which has desirable characteristics for imaging with the gamma camera and a suitably long half-life to match biological timescales for drug uptake and turnover, has been overlooked, in particular, for treatment planning with radionuclide therapy. Gallium-67 could also allow non-PET facilities to participate in theranostic imaging prior to treatment or for monitoring response after therapy. Gallium-67 could play a niche role in the future development of personalised medicine with theranostics.

Calculated Radioactivity Yields of Gallium-67 using Matlab Codes

In nuclear medicine, gallium-67 (67Ga) is potentially applied for imaging a certain type of tissue. In this investigation, 67Ga is theoretically studied in terms of its potential radioactivity yields at the end of various energetic proton bombardments. Nuclear cross-sections derived from the Talys Evaluated Nuclear Data Library (TENDL) 2017 were used as the input files, while a Matlab code was developed to perform the yield calculations of 67Zn(p,n)67Ga and 68Zn(p,2n)67Ga nuclear reactions to produce 67Ga. Two different targets – enriched 67Zn and natZn targets – were simulated in the calculations. The calculated yields suggested that a maximum of 27.37 MBq/µAh could be achieved when enriched 67Zn target was irradiated with 15-MeV protons, whereas 46.99 MBq/µAh could be generated following a 30 MeV proton bombardment of enriched 68Zn target. Various radioactive gallium impurities, i.e. 63,64,65,66,68,70Ga and stable 69Ga isotope were also expected to be generated mostly via (p,n) and (p,2n) reactions when natZn target was used in the 67Ga production. In contrast, radioactive 66Ga and 68Ga impurities were mainly produced following bombardment of enriched 67Zn and 68Zn targets. This study can be used as a reference for future 67Ga radionuclide production.