FITC-Dextran entrapped and silica coated gadolinium oxide nanoparticles for synchronous optical and magnetic resonance imaging applications

We report, microemulsion mediated synthesis of FITC-dextran dye entrapped and silica coated Gd2O3 nanoparticles (NPs) for dual purpose of optical and magnetic resonance imaging, in the present study. TEM image revealed that the average size of the NPs is 18nm and hydrodynamic diameter of the particles as measured by DLS comes out to be about 16nm. Gd2O3 core show paramagnetism which is affirmed by the NMR line broadening effect on neighboring water proton spectrum and also by magnetization curve obtained in VSM analysis. The fluorescence of the entrapped dye is confirmed by the UV-vis and fluorescence spectroscopy. Nanoencapsulation of FITC-dextran fluorophore was found to increase its optical activity and provided a blanket against quenching. Moreover, TGA data revealed that entrapment of dye imparts thermal stability to it and enhances its fluorescence in comparison to bare dye. The release kinetic pattern (at pH 7.4) of the entrapped dye revealed that these particles behave as non-releasing system. The in-vitro cell viability (SRB) assay of the particles done on normal cell line (HEK-293) as well as cancerous cell line (A-549) indicated non-cytotoxic nature of the particles. In a nut-shell, these particles have the potential to be efficiently used for optical and magnetic resonance imaging. We anticipate that further optimization of these particles can be done by either conjugating or entrapping a drug for targeted drug delivery which would open more prospective options in biomedical field.

PEG coated and doxorubicin loaded multimodal Gadolinium oxide nanoparticles for simultaneous drug delivery and imaging applications

We report water-in-oil microemulsion mediated synthesis of PEG¹ coated Gd₂O₃ NPs² loaded with fluorescent anti-cancer drug dox³ for synchronous drug delivery, optical and MR⁴ imaging applications. These PEG covered Gd₂O₃ NPs loaded with dox (Gd-PEG-dox NPs) were found to possess spherical morphology with 13nm size as measured from TEM and the hydrodynamic diameter comes out to be 37nm as determined from DLS. Fluorescence spectra and fluorescence microscopy images confirmed optical activity of the NPs. The paramagnetic nature of NPs was affirmed by NMR line broadening effect on the spectrum of surrounding water protons. Therefore, these particles can be efficiently used as CA⁵ in MR imaging. In vitro analysis showed significant cellular uptake of particles by A-549 cells. A pH dependent drug release pattern was observed for the NPs. Cell viability assay performed on A-549, PANC-1 and U-87 cancerous cell lines revealed that Gd-PEG-dox NPs are cytotoxic. On the basis of these observations, it can be concluded that these multi-modal paramagnetic NPs promise potential cancer therapy along with optical and MR imaging applications.

Assessment of left ventricular diastolic dysfunction in sub-clinical hypothyroidism

Background:

Adverse cardiovascular effect of hypothyroidism has been identified in many studies. Early identification of patients with sub-clinical hypothyroidism may lead to early treatment and thereby favourable effect on cardiovascular morbidity and mortality.

Objectives:

To find out the association of sub clinical hypothyroidism and left ventricular dysfunction and also to find out relationship between systolic and diastolic dysfunction in these patients.

Material and Methods:

A total 30 cases of sub clinical hypothyroidism along with 15 age sex matched healthy control subjects were included in study. Serum TSH, T4, T3 hormone level was measured and those who were found to have sub-clinical hypothyroidism underwent for 2DEcho.

Results:

Significant reduction in peak early filling velocity (PE) (p<0.001) and early filling time velocity integral (Ei) (p<0.001). Ratio of early and late peak velocities (PE/PA) (p<0.001), ratio of time velocity integral of early and atrial filling (Ei/Ai) (p<0.001) and ratio of the early peak to average velocity (PE/M) (p<0.001) were also reduced. Mean EF was 54.9± 5.55 as compared to 55.7 ± 3.46 of control subjects with a T.value of 0.48 ,however there was significant diastolic dysfunction in case of hypothyroid patients (mean Ei/Ai = 1.35 ± 0.53) as compared to control group subjects (mean Ei/AI = 2.11 ± 0.26) with a T value of 5.22.

Conclusion:

Sub-clinical hypothyroidism showed significant diastolic dysfunction in the absence of significant impairment of systolic function.

Preclinical Evaluation of a Potential GSH Ester Based PET/SPECT Imaging Probe DT(GSHMe)₂ to Detect Gamma Glutamyl Transferase Over Expressing Tumors

Gamma Glutamyl Transferase (GGT) is an important biomarker in malignant cancers. The redox processes ensuing from GGT-mediated metabolism of extracellular GSH are implicated in critical aspects of tumor cell biology. Reportedly, Glutathione monoethyl ester (GSHMe) is a substrate of GGT, which has been used for its rapid transport over glutathione. Exploring GGT to be an important target, a homobivalent peptide system, DT(GSHMe)₂ was designed to target GGT-over expressing tumors for diagnostic purposes. DT(GSHMe)₂ was synthesized, characterized and preclinically evaluated in vitro using toxicity, cell binding assays and time dependent experiments. Stable and defined radiochemistry with ^99mTc and ⁶⁸Ga was optimized for high radiochemical yield. In vivo biodistribution studies were conducted for different time points along with scintigraphic studies of radiolabeled DT(GSHMe)₂ on xenografted tumor models. For further validation, in silico docking studies were performed on GGT (hGGT1, P19440). Preclinical in vitro evaluations on cell lines suggested minimal toxicity of DT(GSHMe)₂ at 100 μM concentration. Kinetic analysis revealed transport of ^99mTc-DT(GSHMe)₂ occurs via a saturable high-affinity carrier with Michaelis constant (Km) of 2.25 μM and maximal transport rate velocity (Vmax) of 0.478 μM/min. Quantitative estimation of GGT expression from western blot experiments showed substantial expression with 41.6 ± 7.07 % IDV for tumor. Small animal micro PET (Positron Emission Tomography)/CT(Computed Tomography) coregistered images depicted significantly high uptake of DT(GSHMe)₂ at the BMG-1 tumor site. ROI analysis showed high tumor to contra lateral muscle ratio of 9.33 in PET imaging studies. Avid accumulation of radiotracer was observed at tumor versus inflammation site at 2 h post i.v. injection in an Ehrlich Ascites tumor (EAT) mice model, showing evident specificity for tumor. We propose DT(GSHMe)₂ to be an excellent candidate for prognostication and tumor imaging using PET/SPECT.

Rose Bengal attached and dextran coated gadolinium oxide nanoparticles for potential diagnostic imaging applications

We report here, reverse micelle mediated synthesis of multifunctional dextran (dex) coated Gd₂O₃ nanoparticles (NPs) carrying rose bengal (RB) dye for magnetic resonance and optical imaging. The diameter of these RB attached dex coated Gd₂O₃ NPs (Gd-dex-RB NPs) was found to be ~17 nm as measured by TEM. NMR line broadening effect on the surrounding water protons affirmed the paramagnetic nature of these NPs. Optical properties of Gd-dex-RB NPs were validated by UV-Vis and fluorescence spectroscopy. Time dependent release profile of RB from NPs at two different pH of 7.4 and 5.0 revealed that these NPs behave as slow releasing system. In-vitro study revealed that NPs are efficiently taken up by cells and show optical activity in cellular environment. In vitro cell viability (SRB) assay was performed on cancerous (A-549, U-87) and normal (HEK-293) cell lines, showed the absence of cytotoxic effect of Gd-dex-RB NPs. Therefore, such multifunctional NPs can be efficiently used for bio-imaging and optical tracking.

Biotinidase Resistant 68Gallium-Radioligand Based on Biotin/Avidin Interaction for Pretargeting: Synthesis and Preclinical Evaluation

A new macrocyclic system 2,2'-(12-amino-11,13-dioxo-1,4,7,10-tetraazacyclotridecane-4,7-diyl)diacetic acid (ATRIDAT) was designed for coordinating metals in +2 and +3 oxidation states particularly ⁶⁸Ga(III), for PET imaging. ATRIDAT was conjugated to d-biotin for pretargeting via biotin-avidin interaction. This model provides high tumor targeting efficiency and stability to biotinidase activity leading to modest signal amplification at the tumor site. Cyclization of triethylenetetramine with protected diethylamino malonate resulted in the formation of 13 membered diamide ring. d-Biotin was then anchored on the pendant amine rendering α-methyne carbon to the biotinamide bond which blocks the biotinidase enzyme activity. Biotinidase stability assay showed remarkable stability toward the action of biotinidase with ∼95% remaining intact after treatment following 4 h. Binding affinity experiments such as HABA assay, competitive displacement studies with d-biotin and CD showed high binding affinity of the molecule with avidin in nanomolar range. Biotin conjugate was successfully radiolabeled with ⁶⁸Ga(III) with radiolabeling efficiency of ∼70% and then purified to get 99.9% radiochemical yield. IC₅₀ of the compound was found to be 2.36 mM in HEK cell line and 0.82 mM in A549 as assessed in MTT assay. In biodistribution studies, the major route of excretion was found to be renal. Significant uptake of 4.15 ± 0.35% was observed in tumor in the avidin pretreated mouse at 1 h. μPET images also showed a high tumor to muscle ratio of 26.8 and tumor to kidney ratio of 1.74 at 1 h post-injection after avidin treatment.

Synthesis, preclinical evaluation and molecular modelling of macrocyclic appended 1-(2-methoxyphenyl)piperazine for 5-HT1A neuroreceptor imaging

An efficient approach in the design and synthesis of a multi-functional chelating agent based on 1-(2-methoxyphenyl)piperazine for targeting 5-HT_1A receptors in brain was envisaged.

Radiolabeling and Preclinical Evaluation of a New S-Alkylated Cysteine Derivative Conjugated to C-Substituted Macrocycle for Positron Emission Tomography

A new S-alkylated cysteine-derivatized tumor targeting agent, 2,2'-(12-(2-((2-acetamido-2-carboxyethyl)thio)acetamido)-11,13-dioxo-1,4,7,10-tetraazacyclotridecane-4,7-diyl)diacetic acid was developed for positron emission tomography (PET) imaging. N-Acetyl cysteine (NAC) was conjugated to ATRIDAT as a specific targeting agent toward L-type and ASC amino acid transporter systems in the oncogenic cells. NAC was attached via S-alkylation to prevent its incorporation at undesired recognition sites affecting the signal-to-noise ratio. NAC-ATRIDAT was subjected to gallium-68 complexation with >75% radiolabeling yield. The radiocomplex was purified through the tc18 cartridge to obtain 99.89% radiochemical yield. IC-50 of the NAC-ATRIDAT conjugate was 0.8 mM in A549 cells as evaluated through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazonium bromide assay. Binding affinity experiments on A549 cells showed noteworthy binding with K_D in the nanomolar range. A time course study showed a K_m value of 0.19 μM and V_max value of 0.49 pmol/μg protein/min showing reasonable tumor kinetics. Efflux studies showed that the synthesized radioligand is transported majorly by LAT followed by the ASC system. Clearance was found to be renal with 7.67 ± 1.48% ID/g uptake at 30 min which substantially declined to 0.52 ± 0.% ID/g at 4 h. A significant uptake of 10.06 ± 1.056% ID/g was observed at the tumor site in mice at 1 h. μPET images revealed a high contrast with a tumor-to-kidney ratio of 4.8 and a tumor-to-liver ratio of 35.85 at 1 h after injection. These preclinical in vitro and in vivo evaluation supports its potential on the way of becoming a successful ⁶⁸Ga-radiolabeled amino acid-based PET imaging agent.

Exploring Niclosamide as a Multi-target Drug Against SARS-CoV-2: Molecular Dynamics Simulation Studies on Host and Viral Proteins

Niclosamide has emerged as a promising repurposed drug against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In vitro studies suggested that niclosamide inhibits the host transmembrane protein 16F (hTMEM16F), crucial for lipid scramblase activity, which consequently reduces syncytia formation that aids viral spread. Based on other in vitro reports, niclosamide may also target viral proteases such as papain-like protease (PLpro) and main protease (Mpro), essential for viral replication and maturation. However, the precise interactions by which niclosamide interacts with these multiple targets remain largely unclear. Docking and molecular dynamics (MD) simulation studies were undertaken based on a homology model of the hTMEM16F and available crystal structures of SARS-CoV-2 PLpro and Mpro. Niclosamide was observed to bind stably throughout a 400 ns MD simulation at the extracellular exit gate of the hTMEM16F tunnel, forming crucial interactions with residues spanning the TM1-TM2 loop (Gln350), TM3 (Phe481), and TM5-TM6 loop (Lys573, Glu594, and Asp596). Among the SARS-CoV-2 proteases, niclosamide was found to interact effectively with conserved active site residues of PLpro (Tyr268), exhibiting better stability in comparison to the control inhibitor, GRL0617. In conclusion, our in silico analyses support niclosamide as a multi-targeted drug inhibiting viral and host proteins involved in SARS-CoV-2 infections.

A Rare Case of Endolymphatic Sac Tumour: Clinical, Radiological, Pathological and Immunohistochemical Findings with Review of Literature

Endolymphatic sac tumour (ELST) is a rare low grade malignant epithelial tumour of the petrous temporal bone, thought to arise from papillary epithelium of the endolymphatic sac. They may occur sporadically or in association with Von-Hippel Lindau disease. ELST is extremely rare neoplasm with benign histopathological appearance and clinically destructive behaviour. Because of the rarity of this tumour, it can easily be confused with other tumours such as paraganglioma, middle ear adenoma, metastatic carcinomas or choroid plexus papilloma. We report here a rare case of ELST with review of literature and discuss the differentiating features of ELST from its mimickers, showing a papillary configuration.

Toxic Leukoencephalopathy: An unusual Presentation by 5-Fluorouracil Infusion

BACKGROUND

Toxic leukoencephalopathy predominantly affect white matter of the brain parenchyma. Patient presents either in acute, subacute or chronic phase. The clinical presentation may vary, ranging from mild cognitive impairment to severe neurological dysfunction. It can also mimic psychiatric illness.

CASE REPORT

A 50-year-old woman was diagnosed with locally advanced carcinoma buccal mucosa. She was planned for Neoadjuvant chemotherapy consisting of Docetaxel, Cisplatin, 5-FU (TPF). During 3rd day of 3rd cycle of 5-fluorouracil (5FU) infusion, patient developed hypoactive delirium and later became comatose state of drowsiness, with Glasgow Coma Scale (GCS) was 5. There was no previous history for the same. Hence, the infusion was stopped. Patient was evaluated with NCCT head. No abnormality was seen on CT scan. MRI brain was done and it showed diffusion restriction with T2 / FLAIR hyper intensities in bilateral centrum semiovale, white matter of bilateral parietal region and in corpus callosum. Patient received symptomatic care, nutrition by ryles tube during this period and she started to improve after 1st week of onset of symptoms. After 3 weeks, MRI was repeated and there was complete resolution of previous findings.

CONCLUSIONS

Development of neurological symptoms during 5FU infusion is a rare entity. Henceforth, occurrence of toxic leukoencephalopathy should be kept in mind. Diffusion weighted imaging play an important role in both acute episode of toxic encephalopathy and in follow up.

Evolution of drug resistance against antiviral agents that target cellular factors

Antiviral drugs have classically been developed by directly disrupting the functions of viral proteins. However, this strategy has been largely unsuccessful due to the rapid generation of viral escape mutants. It has been well established that as compared to the virus-centric approach, the strategy of developing antiviral drugs by targeting host-dependency factors (HDFs) minimizes drug resistance. However, recent reports have indicated that drug resistance against some of the host-targeting antiviral agents can in fact occur under some circumstances. Long-term selection pressure of a host-targeting antiviral agent may induce the virus to use an alternate cellular factor or alters its affinity towards the target that confers resistance. Alternatively, virus may synchronize its life cycle with the patterns of drug therapy. In addition, virus may subvert host's immune system to perpetuate under the limiting conditions of the targeted cellular factor. This review describes novel potential mechanisms that may account for the acquiring resistance against agents that target HDFs.