BEHAVIORAL AND NEUROCHEMICAL CHANGES DURING INTRANASAL ADMINISTRATION OF ALPHA-GLUTAMYL-TRYPTOPHAN AND CHELATE COMPLEX OF ZINC ARGINYL-GLYCINATE ON MONOAMINE SYSTEMS DYSFUNCTIONS KNOCK-OUT MODELS.

Monoamine neurotransmitter system dysfunctions lead to behavioral disorders, cognitive metabolic, and other pathological conditions. In this case, different amino acids are precursors of monoamines, while the parenteral path of monoamine administration has pharmacological restrictions. Therefore, intranasal administration one of the most promising methods of delivering an active substance is. The purpose of the work is to study the effect of intranasal administration of a chelate complex of zinc arginyl-glycinate and alpha-glutamyl-tryptophan dipeptide on behavioral and neurochemical changes in acute and chronic experiments. MATERIAL AND METHODS: The studies used outbred Wistar and DAT-KO rats, and inbred C57Bl6 and TAAR1-KO mice. Using intranasal administration of a chelate complex of zinc arginyl-glycinate and alpha-glutamyl-tryptophan dipeptide we tested methods for evaluating different behavioral indicators and the level of cerebral monoamines and their metabolites. RESULTS: An anxiolytic effect of zinc arginyl-glycinate and its combination with alpha-glutamyl-tryptophan was revealed. Both drugs have a physiological effect on the autonomic nervous system, but the determination of their operating mechanisms requires further research. CONCLUSION: Thus, these data indicate that intranasal delivery of the dipeptides is effective during acute and chronic intranasal administration in rodents, the latter showed a change in the anxiety indicator. Acute AG intranasal administration demonstrated signs of lower anxiety and depressive-like behavior in C57Bl6 mice. The acute intranasal administration of a chelate complex zinc arginyl-glycinate and combination with alpha-glutamyl-tryptophan in doses of 50-100 mg/kg of body weight may be used for pre-clinical studies as a new anxiolytic/antidepressant.

Relapse following withdrawal of D-penicillamine from combination (D-penicillamine + zinc) therapy in hepatic Wilson disease.

OBJECTIVES: Long-term D-penicillamine (D-pen) therapy in Wilson disease (WD) has numerous adverse effects which advocates its withdrawal, but with an inherent risk of relapse. This prospective observational study was conducted with the objective of evaluating incidence of relapse following withdrawal of D-pen from combination (D-pen + zinc) therapy in maintenance phase of previously symptomatic hepatic WD. METHODS: Hepatic WD patients <18 years of age and on combination therapy for >2 years with 6 months of biochemical remission were included. Biochemical remission was defined as achievement of (i) aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤1.5 times upper limit of normal (ULN), (ii) serum albumin >3.5 g/dL, international normalized ratio (INR) <1.5 and (iii) 24-h urinary copper excretion (UCE) <500 mcg/day, nonceruloplasmin-bound-copper (NCC) <15 mcg/dL. After D-pen withdrawal, monthly liver function test (LFT) and INR and 3 monthly UCE and NCC were done till 1 year or relapse (elevation of AST/ALT/both >2 times ULN or total bilirubin >2 mg/dL), whichever occurred earlier. RESULTS: Forty-five patients enrolled with median combination therapy duration of 36 months. Sixty percent of them had their index presentation as decompensated cirrhosis. Fourteen patients (31.8%) relapsed (cumulative incidence: 4 at 3 months, 11 at 6 months, and 14 at 12 months after D-pen discontinuation). All relapsers had index presentation as decompensated cirrhosis. On Cox-regression, ALT at D-pen withdrawal was an independent predictor of relapse (hazard ratio [HR]: 1.077, 95% confidence interval [CI]: 1.014-1.145, p = 0.017) with area under the receiver operating characteristic (AUROC) of 0.860. ALT ≥40 U/L predicted risk of relapse with 85.7% sensitivity, 70.9% specificity. CONCLUSION: Incidence of relapse after withdrawal of D-pen from combination therapy is 31.8% in hepatic WD. ALT ≥40 U/L, at the time of D-pen stoppage, predicts future relapse.

Effects of pharmacological inhibition of the sodium-dependent phosphate cotransporter 2b (NPT2b) on intestinal phosphate absorption in mouse and rat models.

An excess phosphate burden in renal disease has pathological consequences for bone, kidney, and heart. Therapies to decrease intestinal phosphate absorption have been used to address the problem, but with limited success. Here, we describe the in vivo effects of a novel potent inhibitor of the intestinal sodium-dependent phosphate cotransporter NPT2b, LY3358966. Following treatment with LY3358966, phosphate uptake into plasma 15 min following an oral dose of radiolabeled phosphate was decreased 74% and 22% in mice and rats, respectively, indicating NPT2b plays a much more dominant role in mice than rats. Following the treatment with LY3358966 and radiolabeled phosphate, mouse feces were collected for 48 h to determine the ability of LY3358966 to inhibit phosphate absorption. Compared to vehicle-treated animals, there was a significant increase in radiolabeled phosphate recovered in feces (8.6% of the dose, p < .0001). Similar studies performed in rats also increased phosphate recovered in feces (5.3% of the dose, p < .05). When used in combination with the phosphate binder sevelamer in rats, there was a further small, but not significant, increase in fecal phosphate. In conclusion, LY3358966 revealed a more prominent role for NPT2b on acute intestinal phosphate uptake into plasma in mice than rats. However, the modest effects on total intestinal phosphate absorption observed in mice and rats with LY3359866 when used alone or in combination with sevelamer highlights the challenge to identify new more effective therapeutic targets and/or drug combinations to treat the phosphate burden in patients with renal disease.

Copper chelation in patients with hypertrophic cardiomyopathy.

BACKGROUND: Disturbances of copper (Cu) homeostasis can lead to hypertrophic cardiac phenotypes (eg, Wilson's disease). We previously identified abnormal Cu homeostasis in patients with hypertrophic cardiomyopathy (HCM) and, therefore, hypothesised that Cu2+-selective chelation with trientine dihydrochloride may slow or reverse disease progression in HCM. The aim of this study was, therefore to explore the clinical efficacy, safety and tolerability of trientine in HCM. METHODS: In this medicines and healthcare products regulatory agency (MHRA) registered open-label pilot study, we treated 20 HCM patients with trientine for 6 months. Patients underwent a comprehensive assessment schedule including separate cardiac magnetic resonance imaging (CMR) and CMR 31P-spectroscopy at baseline and end of therapy. Predefined end points included changes in left ventricular mass (LVM), markers of LV fibrosis, markers of LV performance and myocardial energetics. Ten matched patients with HCM were studied as controls. RESULTS: Trientine treatment was safe and tolerated. Trientine caused a substantial increase in urinary copper excretion (0.42±0.2 vs 2.02±1.0, p=0.001) without affecting serum copper concentrations. Treatment was associated with significant improvements in total atrial strain and global longitudinal LV strain using both Echo and CMR. LVM decreased significantly in the treatment arm compared with the control group (-4.2 g v 1.8 g, p=0.03). A strong trend towards an absolute decrease in LVM was observed in the treatment group (p=0.06). These changes were associated with a significant change in total myocardial volume driven by a significant reduction in extracellular matrix (ECM) volume (43.83±18.42 mL vs 41.49±16.89 mL, p=0.04) as opposed to pure cellular mass reduction and occurred against a background of significant ECM volume increase in the control group (44.59±16.50 mL vs 47.48±19.30 mL, p=0.02). A non-significant 10% increase in myocardial phosphocreatine/adenosine triphosphate (PCr/ATP) ratio with trientine therapy (1.27±0.44 vs 1.4±0.39) was noted. CONCLUSIONS: Cu2+-selective chelation with trientine in a controlled environment is safe and a potential future therapeutic target. A phase 2b trial is now underway.

Attenuation of ischemia-reperfusion injury by intracoronary chelating agent administration.

Ischemia-reperfusion (IR) injury accelerates myocardial injury sustained during the myocardial ischemic period and thus abrogates the benefit of reperfusion therapy in patients with acute myocardial infarction. We investigated the efficacy of intracoronary ethylenediaminetetraacetic acid (EDTA) administration as an adjunctive treatment to coronary intervention to reduce IR injury in a swine model. We occluded the left anterior descending artery for 1 h. From the time of reperfusion, we infused 50 mL of EDTA-based chelating agent via the coronary artery in the EDTA group and normal saline in the control group. IR injury was identified by myocardial edema on echocardiography. Tetrazolium chloride assay revealed that the infarct size was significantly lower in the EDTA group than in the control group, and the salvage percentage was higher. Electron microscopy demonstrated that the mitochondrial loss in the cardiomyocytes of the infarcted area was significantly lower in the EDTA group than in the control group. Echocardiography after 4 weeks showed that the remodeling of the left ventricle was significantly less in the EDTA group than in the control group: end-diastolic dimension 38.8 ± 3.3 mm vs. 43.9 ± 3.7 mm (n = 10, p = 0.0089). Left ventricular ejection fraction was higher in the EDTA group (45.3 ± 10.3 vs. 34.4 ± 11.8, n = 10, respectively, p = 0.031). In a swine model, intracoronary administration of an EDTA chelating agent reduced infarct size, mitochondrial damage, and post-infarct remodeling. This result warrants further clinical study evaluating the efficacy of the EDTA chelating agent in patients with ST-segment elevation myocardial infarction.

Success of small-dose fractionated sodium thiosulfate in the treatment of calciphylaxis in a peritoneal dialysis patient.

BACKGROUND: Calciphylaxis, or calcific uremic arteriolopathy (CUA), is a rare, fatal disorder of microvascular calcification and thrombosis that typically affects patients with end-stage renal disease (ESRD) receiving long-term dialysis. Fewer reports describe calciphylaxis in peritoneal dialysis patients than hemodialysis patients as per a literature review. To date, there are no clear guidelines for CUA diagnosis and treatment. While sodium thiosulfate (STS) has been increasingly used for treatment in recent years, there have also been reports of severe side effects. There is no uniform standard for its usage and dosage, especially for peritoneal dialysis patients. CASE PRESENTATION: We present a case of a 40-year-old Chinese male patient with ESRD on peritoneal dialysis who developed calciphylaxis with severe painful cutaneous ulcers on the fingers and toes that were managed successfully for 6 months with comprehensive treatment composed mainly of small-dose fractionated sodium thiosulfate. CONCLUSIONS: Our experience suggests that the treatment of calciphylaxis requires timely and multi-angle intervention. Treatment with small-dose fractionated sodium thiosulfate has proven effective and tolerated in this patient.

Association of fibroblast growth factor 23 and α-klotho in hemodialysis patients during administration of ferric citrate hydrate: post hoc analysis of ASTRIO study.

BACKGROUND: Fibroblast growth factor-23 (FGF23) and α-klotho are associated with anemia in patients with chronic kidney disease. In this post hoc analysis of the ASTRIO study (UMIN000019176), we investigated the relationship between FGF23 and α-klotho during treatment with an iron-based phosphate binder, ferric citrate hydrate (FC), compared with non-iron-based phosphate binders in hemodialysis (HD) patients. We examined the effect of iron absorption by FC on the relationship between FGF23 and α-klotho. There have been few clinical studies evaluating these biomarkers simultaneously in HD patients. METHODS: The ASTRIO study was a 24-week, randomized, open-label, multicenter trial. HD patients taking non-iron-based phosphate binder(s) were randomized at a 1:1 ratio to continue other binder(s) (control group) or switch to FC (FC group). Serum phosphate (P) and hemoglobin (Hb) were maintained within 3.5-6.0 mg/dL and 10-12 g/dL, respectively. Plasma levels of intact FGF23 (i-FGF23), C-terminal FGF23 (c-FGF23), and α-klotho were measured, as were iron-related parameters. Association analyses of FGF23 and α-klotho were conducted. RESULTS: Patients were randomized to FC (n = 48) and control (n = 45) groups. Serum ferritin significantly increased from baseline to end-of-treatment (EOT) in the FC group, compared with the control group (adjusted mean difference [95% confidence interval]: 79.5 [44.7, 114.4] ng/mL; p <  0.001). The mean change from baseline to EOT in c-FGF23 was significantly different between the FC and control groups (mean ± standard deviation (SD): - 0.2 ± 0.8 loge pg/mL vs. 0.2 ± 0.8 loge pg/mL, respectively; p = 0.04). The mean change from baseline to EOT in i-FGF23 and α-klotho were not significantly different between the FC and control groups (mean ± SD: - 0.1 ± 0.8 loge pg/mL vs. 0.1 ± 0.9 loge pg/mL; p = 0.33, and 2.0 ± 91.5 pg/mL vs. - 8.9 ± 145.3; p = 0.58, respectively). However, both forms of FGF23 and α-klotho were not significantly associated with each other in both groups. CONCLUSIONS: Iron absorbed via FC administration in HD patients did not influence the correlation relationship between plasma levels of FGF23 and α-klotho under the condition of serum P and Hb were maintained. TRIAL REGISTRATION: ASTRIO study ( UMIN000019176 , registered at UMIN Clinical Trials Registry on October 1, 2015).

A 1,10-phenanthroline derivative selectively targeting telomeric G-quadruplex induces cytoprotective autophagy, causing apoptosis of gastric cancer cells.

AIMS: This study aimed to evaluate the ability of compound 13d to induce autophagy and to promote apoptosis of tumor cells and its interaction mechanism. MATERIALS AND METHODS: Using CCK-8 assay, transwell assay, fluorescence resonance energy transfer melting analysis (FRET), transmission electron microscopy, flow cytometry assay, immunofluorescence assay, Western blot analysis, and wound healing assay. KEY FINDINGS: The results indicated that compound 13d could induce autophagy and apoptosis of gastric cancer cells. Moreover, the findings of CCK-8 assay, colony formation, migration and invasion assay, and wound healing assay revealed that compound 13d would effectively inhibit cell proliferation, migration, and invasion. Its IC50 value is about 2.4 µM against gastric cancer cells, which is similar to positive drug­platinum. 13d specific induction of telomere G-quadruplex formation was proved in extracellular FRET melting assay, and indirectly affected telomerase activity. G-quadruplex formation promoted cell apoptosis and autophagy. Upon incorporating the autophagy inhibitors 3-MA and HCQ, the expression of the autophagy marker protein LC3 was then checked, suggesting that the compound 13d influences the autophagy flux. Furthermore, knocking down the autophagy-related gene Atg5 to reduce the level of autophagy enhances the anti-tumor activity and increases apoptotic cells' proportion. Mechanistic experiments have shown that blocking the Akt/m-TOR signal pathway plays a crucial role in autophagy and G-quadruplex induced telomere dysfunction. DNA damage is the leading cause of autophagy. Compound 13d combined with autophagy inhibitor can inhibit tumor cells more effectively. SIGNIFICANCE: Our findings demonstrate that compound 13d as a telomeric G-quadruplex ligand induces Telomere dysfunction, DNA damage response, autophagy, and apoptosis in gastric cancer cells by blocking the Akt/m-TOR signaling pathway.

One-step, kit-based radiopharmaceuticals for molecular SPECT imaging: a versatile diphosphine chelator for 99mTc radiolabelling of peptides.

Radiotracers labelled with technetium-99m (99mTc) enable accessible diagnostic imaging of disease, provided that radiotracer preparation is simple. Whilst 99mTc radiopharmaceuticals for imaging perfusion are routinely prepared from kits, and regularly used in healthcare, there are no 99mTc-labelled receptor-targeted radiopharmaceuticals in widespread clinical use. This is in part due to the multistep radiosyntheses required for the latter. We demonstrate that the diphosphine, 2,3-bis(diphenylphosphino)maleic anhydride (BMA), is an excellent platform for preparation of kit-based, receptor-targeted 99mTc-labelled radiotracers: its conjugates are simple to prepare and can be easily labelled with 99mTc using one-step, kit-based protocols. Here, reaction of BMA with the αvß3-integrin receptor targeted cyclic peptide, Arg-Gly-Asp-DPhe-Lys (RGD), provided the first diphosphine-peptide conjugate, DP-RGD. DP-RGD was incorporated into a "kit", and addition of a saline solution containing 99mTcO4- to this kit, followed by heating, furnished the radiotracer [99mTcO2(DP-RGD)2]+ in consistently high radiochemical yields (>90%). The analogous [ReO2(DP-RGD)2]+ compound was prepared and characterised, revealing that both [99mTcO2(DP-RGD)2]+ and [ReO2(DP-RGD)2]+ consist of a mixture of cis and trans geometric isomers. Finally, [99mTcO2(DP-RGD)2]+ exhibited high metabolic stability, and selectively targeted αvß3-integrin receptors, enabling in vivo SPECT imaging of αvß3-integrin receptor expression in mice.

Protein-Bound Uremic Toxins Lowering Effect of Sevelamer in Pre-Dialysis Chronic Kidney Disease Patients with Hyperphosphatemia: A Randomized Controlled Trial.

P-cresyl sulfate and indoxyl sulfate are strongly associated with cardiovascular events and all-cause mortality in chronic kidney disease (CKD). This randomized controlled trial was conducted to compare the effects between sevelamer and calcium carbonate on protein-bound uremic toxins in pre-dialysis CKD patients with hyperphosphatemia. Forty pre-dialysis CKD patients with persistent hyperphosphatemia were randomly assigned to receive either 2400 mg of sevelamer daily or 1500 mg of calcium carbonate daily for 24 weeks. A significant decrease of total serum p-cresyl sulfate was observed in sevelamer therapy compared to calcium carbonate therapy (mean difference between two groups -5.61 mg/L; 95% CI -11.01 to -0.27 mg/L; p = 0.04). There was no significant difference in serum indoxyl sulfate levels (p = 0.36). Sevelamer had effects in terms of lowering fibroblast growth factor 23 (p = 0.01) and low-density lipoprotein cholesterol levels (p = 0.04). Sevelamer showed benefits in terms of retarding CKD progression. Changes in vascular stiffness were not found in this study.

A safety evaluation of sucroferric oxyhydroxide for the treatment of hyperphosphatemia.

INTRODUCTION: Hyperphosphatemia is a common complication as chronic kidney disease (CKD) progresses and most patients undergoing dialysis are prescribed oral phosphate binder therapy to control serum phosphate concentrations. Sucroferric oxyhydroxide is an iron-based phosphate binder approved for the treatment of hyperphosphatemia in CKD patients on dialysis. AREAS COVERED: This article reviews key safety and effectiveness data for sucroferric oxyhydroxide from both prospective clinical trials and real-world observational studies. EXPERT OPINION: Sucroferric oxyhydroxide potently binds dietary phosphate in the gastrointestinal (GI) tract, resulting in effective reduction of serum phosphate concentrations with a relatively low daily pill burden. Data from clinical trials and real-world observational studies show sucroferric oxyhydroxide has a favorable safety and tolerability profile. The most frequent side effects observed with sucroferric oxyhydroxide are GI-related, mainly discolored (black) stools and mild or moderate transient diarrhea, both of which are manageable. There is minimal systemic iron absorption from sucroferric oxyhydroxide, and therefore the drug is associated with a low risk of iron accumulation. Sucroferric oxyhydroxide also displays low potential for drug-drug interactions with other commonly prescribed oral medications. Overall, sucroferric oxyhydroxide offers an effective and well-tolerated treatment option for the management of hyperphosphatemia.

Comparison of the Pharmacokinetic Profiles of Trientine Tetrahydrochloride and Trientine Dihydrochloride in Healthy Subjects.

BACKGROUND AND OBJECTIVE: Wilson disease (WD) is an autosomal recessive inherited disorder of copper metabolism. Chelation of excessive copper is recommended but data on the pharmacokinetics of trientine are limited. The aim of this study was to compare the pharmacokinetics of a new trientine tetrahydrochloride formulation (TETA 4HCl) with those of an established trientine dihydrochloride (TETA 2HCl) salt. METHODS: A randomised single-centre crossover study to evaluate the pharmacokinetics, safety and tolerability of two different oral formulations of trientine (TETA 4HCl tablets vs TETA 2HCl capsules) in 23 healthy adult subjects receiving a single dose equivalent to 600 mg of trientine base was performed. RESULTS: Following oral administration, the median time to reach maximum plasma concentration (Tmax) was 2.00 h (TETA 4HCl) and 3.00 h (TETA 2HCl). The rate (maximum plasma concentration [Cmax]) and extent (area under the plasma concentration-time curve from time zero to infinity [AUC0-∞]) of absorption of the active moiety, trientine, were greater (by approximately 68% and 56%, respectively) for TETA 4HCl than for the TETA 2HCl formulation. The two formulations presented a similar terminal elimination rate (λz) and a similar terminal half-life (t½) for trientine. Differences between TETA 4HCl and TETA 2HCl in the levels of the two main mono- and diacetylated metabolites were less than seen for trientine. For both tested formulations, healthy male volunteers demonstrated higher trientine plasma levels but lower mono- and diacetylated metabolite levels compared with females, with no sex differences in terminal half-life (t½) observed. Single oral doses of both formulations were safe and well tolerated. CONCLUSIONS: Compared with an identical dose of a TETA 2HCl formulation, the TETA 4HCl formulation provided more rapid absorption of trientine and greater systemic exposure in healthy subjects. Clinical Trials Number EudraCT # 2015-002199-25.

Copper-lowering agents as an adjuvant in chemotherapy.

Copper is an important element essential for metabolism and normal human body function. Although it is an essential element, related imbalance leads to toxic effects. Studies have proved that there is an increase in copper level in cancer cells. Evidences suggest the link between increase in copper levels and progression of various types of cancers. Different strategies have been utilized to decrease the level of copper in various types of cancer cells. However, it was observed that cell machinery involved in copper homeostasis plays critical factor in lowering copper levels in cancer cells. The outcomes of many monotherapies consisting copper-lowering agents for the treatment of different types of cancers showed that the inhibition of single factor is not sufficient to inhibit the growth of cancer cells. The combination of copper-lowering agent with chemotherapeutic agent showed synergistic effect. Interestingly, the presence of copper-lowering agent in such combinations significantly improved the efficacy of chemotherapeutic agent. The present work has focused on the discussion of outcomes of studies involving anti-copper agent and chemotherapeutic agent and related future strategies.

Perspectives on metals-based radioimmunotherapy (RIT): moving forward.

Radioimmunotherapy (RIT) is FDA-approved for the clinical management of liquid malignancies, however, its use for solid malignancies remains a challenge. The putative benefit of RIT lies in selective targeting of antigens expressed on the tumor surface using monoclonal antibodies, to systemically deliver cytotoxic radionuclides. The past several decades yielded dramatic improvements in the quality, quantity, recent commercial availability of alpha-, beta- and Auger Electron-emitting therapeutic radiometals. Investigators have created new or improved existing bifunctional chelators. These bifunctional chelators bind radiometals and can be coupled to antigen-specific antibodies. In this review, we discuss approaches to develop radiometal-based RITs, including the selection of radiometals, chelators and antibody platforms (i.e. full-length, F(ab')2, Fab, minibodies, diabodies, scFv-Fc and nanobodies). We cite examples of the performance of RIT in the clinic, describe challenges to its implementation, and offer insights to address gaps toward translation.

Phosphate, Microbiota and CKD.

Phosphate is a key uremic toxin associated with adverse outcomes. As chronic kidney disease (CKD) progresses, the kidney capacity to excrete excess dietary phosphate decreases, triggering compensatory endocrine responses that drive CKD-mineral and bone disorder (CKD-MBD). Eventually, hyperphosphatemia develops, and low phosphate diet and phosphate binders are prescribed. Recent data have identified a potential role of the gut microbiota in mineral bone disorders. Thus, parathyroid hormone (PTH) only caused bone loss in mice whose microbiota was enriched in the Th17 cell-inducing taxa segmented filamentous bacteria. Furthermore, the microbiota was required for PTH to stimulate bone formation and increase bone mass, and this was dependent on bacterial production of the short-chain fatty acid butyrate. We review current knowledge on the relationship between phosphate, microbiota and CKD-MBD. Topics include microbial bioactive compounds of special interest in CKD, the impact of dietary phosphate and phosphate binders on the gut microbiota, the modulation of CKD-MBD by the microbiota and the potential therapeutic use of microbiota to treat CKD-MBD through the clinical translation of concepts from other fields of science such as the optimization of phosphorus utilization and the use of phosphate-accumulating organisms.

Albumin-based nanoparticles as contrast medium for MRI: vascular imaging, tissue and cell interactions, and pharmacokinetics of second-generation nanoparticles.

This multidisciplinary study examined the pharmacokinetics of nanoparticles based on albumin-DTPA-gadolinium chelates, testing the hypothesis that these nanoparticles create a stronger vessel signal than conventional gadolinium-based contrast agents and exploring if they are safe for clinical use. Nanoparticles based on human serum albumin, bearing gadolinium and designed for use in magnetic resonance imaging, were used to generate magnet resonance images (MRI) of the vascular system in rats ("blood pool imaging"). At the low nanoparticle doses used for radionuclide imaging, nanoparticle-associated metals were cleared from the blood into the liver during the first 4 h after nanoparticle application. At the higher doses required for MRI, the liver became saturated and kidney and spleen acted as additional sinks for the metals, and accounted for most processing of the nanoparticles. The multiple components of the nanoparticles were cleared independently of one another. Albumin was detected in liver, spleen, and kidneys for up to 2 days after intravenous injection. Gadolinium was retained in the liver, kidneys, and spleen in significant concentrations for much longer. Gadolinium was present as significant fractions of initial dose for longer than 2 weeks after application, and gadolinium clearance was only complete after 6 weeks. Our analysis could not account quantitatively for the full dose of gadolinium that was applied, but numerous organs were found to contain gadolinium in the collagen of their connective tissues. Multiple lines of evidence indicated intracellular processing opening the DTPA chelates and leading to gadolinium long-term storage, in particular inside lysosomes. Turnover of the stored gadolinium was found to occur in soluble form in the kidneys, the liver, and the colon for up to 3 weeks after application. Gadolinium overload poses a significant hazard due to the high toxicity of free gadolinium ions. We discuss the relevance of our findings to gadolinium-deposition diseases.

Safety and feasibility of crushing sevelamer tablets for enteral feeding tube administration.

WHAT IS KNOWN AND OBJECTIVE: Sevelamer is an insoluble polymer indicated for the management of hyperphosphatemia in patients with chronic kidney disease (CKD). The package inserts for both tablet formulations recommend the tablets be administered whole. Due to whole tablets being sometimes inadvertently crushed and the significantly increased cost of sevelamer packets, we evaluated the safety and feasibility of crushed sevelamer tablets for enteral feeding tube administration. METHODS: A single-centre retrospective chart review was performed. All adult ICU patients prescribed sevelamer carbonate between 1 January 2015 and 31 July 2019 were included if they received at least one dose of a sevelamer tablet or packet, whereas they had an enteral feeding tube in place. The primary outcome was the incidence of an obstructed enteral feeding tube or need for replacement, as defined as the number of occurrences over the total numbers of doses administered. The secondary outcome was the change in phosphorus levels from time of sevelamer initiation to discontinuation or patient discharge. RESULTS: A total of 14 obstructions were reported, four in the tablet arm and ten in the packet arm (0.4% tablet arm, 0.5% packet arm; P = .5931). Of these, four (29%) required tube replacement and were followed by sevelamer discontinuation. Two (14%) were documented to be due to increased tube feeds and esomeprazole. Six (43%) cases required tube replacement, but no issues arose upon continuation. Only one of the obstructions resulted in a recurrent tube occlusion. WHAT IS NEW AND CONCLUSION: Sevelamer tablets may be crushed and administered via enteral feeding tubes, provided clear instruction on tablet preparation is included. Oral administration in dysphagic patients requires further evaluation with clear protocols for preparation and administration.

Power Function Retention of Radionuclides in a Wound.

NCRP Report 156 describes soluble radionuclide retention kinetics in a wound, segregated into four retention categories: weak (W), moderate (M), strong (S), and avid (A). An alternate single-parameter model, the negative power function, t, is presented in this paper to describe the time behavior of radionuclide retention. With this mathematical description, γ is a single parameter that can be used to assign the wound retention category rapidly. Using the power function description of wound retention, the various wound categories present as straight lines on log scales with different slopes corresponding to the various retention categories. Regression analysis of average retention values in NCRP 156 shows γ = 0.735 ± 0.132, 0.514 ± 0.015, 0.242 ± 0.016, and 0.053 ± 0.023 for the weak, moderate, strong, and avid categories, respectively. A case study is presented (REAC/TS Registry case 1284) where a power function is shown to fit retention data in a Pu/Am hand wound up to 2,000 d (5.4 y) post-accident.