Pharmacokinetics of Single Domain Antibodies and Conjugated Nanoparticles Using a Hybrid near Infrared Method.

Iron oxide nanoparticles and single domain antibodies from camelids (VHHs) have been increasingly recognized for their potential uses for medical diagnosis and treatment. However, there have been relatively few detailed characterizations of their pharmacokinetics (PK). The aim of this study was to develop imaging methods and pharmacokinetic models to aid the future development of a novel family of brain MRI molecular contrast agents. An efficient near-infrared (NIR) imaging method was established to monitor VHH and VHH conjugated nanoparticle kinetics in mice using a hybrid approach: kinetics in blood were assessed by direct sampling, and kinetics in kidney, liver, and brain were assessed by serial in vivo NIR imaging. These studies were performed under "basal" circumstances in which the VHH constructs and VHH-conjugated nanoparticles do not substantially interact with targets nor cross the blood brain barrier. Using this approach, we constructed a five-compartment PK model that fits the data well for single VHHs, engineered VHH trimers, and iron oxide nanoparticles conjugated to VHH trimers. The establishment of the feasibility of these methods lays a foundation for future PK studies of candidate brain MRI molecular contrast agents.

Perfluorobutanoic acid (PFBA): No high-level accumulation in human lung and kidney tissue.

Perfluorobutanoic acid (PFBA) belongs to the complex group of synthetic perfluoroalkyl substances (PFAS) which have led to ubiquitous environmental contamination. While some of the long-chain compounds accumulate in the human body, the short-chain compound PFBA was found to have a relatively short half-life in blood of a few days, in agreement with relatively low PFBA serum/plasma levels of roughly 0.01 ng/ml in European studies. Surprisingly, very high median levels of PFBA of 807 and 263 ng/g tissue for human lung and kidney autopsy samples, respectively, were reported in a paper of Pérez et al. (2013). This would question the concept of PFAS blood analysis reflecting the body burden of these compounds. To verify the results of high PFBA tissue accumulation in humans, we have analyzed PFBA in a set of 7 lung and 9 kidney samples from tumor patients with a different method of quantification, using high-resolution mass spectrometry with the accurate mass as analytical parameter. The only human sample with a quantifiable amount of PFBA (peak area more than twice above the analytical background signals) contained approximately 0.17 ng/g lung tissue. In the light of our results and considering the analytical problems with the short-chain compound PFBA exhibiting only one mass fragmentation, it appears to be likely that PFBA is not accumulating on a high level in human lung and kidney tissue. In general, the analysis of short-chain PFAS in complex matrices like food or tissue is very challenging with respect to instrumental quantification and possible sample contamination.

Chronic kidney disease linked to SARS-CoV-2 infection: a case report.

BACKGROUND: The recent COVID-19 pandemic has raised concerns about patient diagnosis and follow-up of chronically ill patients. Patients suffering from chronic illnesses, concomitantly infected by SARS-CoV-2, globally tend to have a worse prognosis and poor outcomes. Renal tropism and acute kidney injury following SARS-CoV-2 infection has recently been described in the literature, with elevated mortality rates. Furthermore, patients with pre-existing chronic kidney disease, infected by SARS-CoV-2, should be monitored carefully. Here, we report the case of a 69-year-old patient with splenic marginal zone lymphoma, suffering from longstanding chronic kidney disease following SARS-CoV-2 infection. CASE PRESENTATION: A 69-year-old male patient previously diagnosed with pulmonary embolism and splenic marginal zone lymphoma (Splenomegaly, Matutes 2/5, CD5 negative and CD23 positive), was admitted to the hospital with shortness of breath, fever and asthenia. A nasopharyngeal swab test was performed in addition to a CT-scan, which confirmed SARS-CoV-2 infection. Blood creatinine increased following SARS-CoV-2 infection at 130 µmol/l, with usual values at 95 µmol/l. The patient was discharged at home with rest and symptomatic medical treatment (paracetamol and hydration), then readmitted to the hospital in August 2020. A kidney biopsy was therefore conducted as blood creatinine levels were abnormally elevated. Immunodetection performed in a renal biopsy specimen confirmed co-localization of SARS-CoV2 nucleocapsid and protease 3C proteins with ACE2, Lewis x and sialyl-Lewis x antigens in proximal convoluted tubules and podocytes. Co-localization of structural and non-structural viral proteins clearly demonstrated viral replication in proximal convoluted tubules in this chronically ill patient. Additionally, we observed the co-localization of sialyl-Lewis x and ACE2 receptors in the same proximal convoluted tubules. Reverse Transcriptase-Polymerase Chain Reaction test performed on the kidney biopsy was negative, with very low Ct levels (above 40). The patient was finally readmitted to the haematology department for initiation of chemotherapy, including CHOP protocol and Rituximab. CONCLUSIONS: Our case emphasizes on the importance of monitoring kidney function in immunosuppressed patients and patients suffering from cancer following SARS-CoV-2 infection, through histological screening. Further studies will be required to decipher the mechanisms underlying chronic kidney disease and the putative role of sialyl-Lewis x and HBGA during SARS-CoV-2 infection.

Use of Donor-Derived Cell-Free DNA for Assessment of Allograft Injury in Kidney Transplant Recipients During the Time of the Coronavirus Disease 2019 Pandemic.

BACKGROUND: Kidney allograft biopsy is the gold standard for diagnosis of rejection. Under the current extraordinary circumstances of the coronavirus disease 2019 (COVID-19), in which social distancing is key to limiting the spread of the virus, the model used to provide care to transplant recipients has undergone a very rapid transformation. In the spirit of medical distancing, we have been using the donor-derived cell-free DNA (dd-cfDNA) test for screening for rejection. METHODS: This article describes our experience with this approach between March 15th and May 20th, 2020. RESULTS: This test was obtained for-cause in 23 patients and for monitoring in 9 patients. Normal results aided in forgoing biopsy in 63% of the patients for whom the test was obtained in the outpatient setting. The test is neither 100% sensitive nor specific for rejection; however, when used in combination with the available clinical information, it can be used for determining whether bringing in a transplant recipient into a medical facility is necessary. CONCLUSIONS: In the event COVID-19 becomes a long-term challenge for our community, noninvasive biomarkers such as the dd-cfDNA may become more relevant than ever in enhancing our ability to care for our transplant patients while maximizing the distancing measures.