Identification of a Carcinoembryonic Antigen Gene Family in the Rat

The existence of a carcinoembryonic antigen (CEA)-like gene family in rat has been demonstrated through isolation and sequencing of the N- terminal domain exons of presumably five discrete genes (rnCGM1-5). This finding will allow for the first time the study of functional and clinical aspects of the tumor marker CEA and related antigens in an animal model. Sequence comparison with the corresponding regions of members of the human CEA gene family revealed a relatively low similarity at the amino acid level, which indicates rapid divergence of the CEA gene family during evolution and explains the lack of cross- reactivity of rat CEA-like antigens with antibodies directed against human CEA. The N-terminal domains of the rat CEA-like proteins show structural similarity to immunoglobulin variable domains, including the presence of hypervariable regions, which points to a possible receptor function of the CEA family members. Although so far only one of the five rat CEA-like genes could be shown to be transcriptionally active, multiple mRNA species derived from other members of the rat CEA-like gene family have been found to be differentially expressed in rat placenta and liver

Monitoring the Stability of Perfluorocarbon Nanoemulsions by Cryo-TEM Image Analysis and Dynamic Light Scattering.

Perfluorocarbon nanoemulsions (PFC-NE) are disperse systems consisting of nanoscale liquid perfluorocarbon droplets stabilized by an emulsifier, usually phospholipids. Perfluorocarbons are chemically inert and non-toxic substances that are exhaled after in vivo administration. The manufacture of PFC-NE can be done in large scales by means of high pressure homogenization or microfluidization. Originally investigated as oxygen carriers for cases of severe blood loss, their application nowadays is more focused on using them as marker agents in 19F Magnetic Resonance Imaging (19F MRI). 19F is scarce in organisms and thus PFC-NE are a promising tool for highly specific and non-invasive imaging of inflammation via 19F MRI. Neutrophils, monocytes and macrophages phagocytize PFC-NE and subsequently migrate to inflamed tissues. This technique has proven feasibility in numerous disease models in mice, rabbits and mini pigs. The translation to clinical trials in human needs the development of a stable nanoemulsion whose droplet size is well characterized over a long storage time. Usually dynamic light scattering (DLS) is applied as the standard method for determining particle sizes in the nanometer range. Our study uses a second method, analysis of transmission electron microscopy images of cryo-fixed samples (Cryo-TEM), to evaluate stability of PFC-NE in comparison to DLS. Four nanoemulsions of different composition are observed for one year. The results indicate that DLS alone cannot reveal the changes in particle size, but can even mislead to a positive estimation of stability. The combination with Cryo-TEM images gives more insight in the particulate evolution, both techniques supporting one another. The study is one further step in the development of analytical tools for the evaluation of a clinically applicable perfluorooctylbromide nanoemulsion

Initial dynamic light scattering analysis of nanoemulsions.

<p>d_z is the intensity-weighted hydrodynamic diameter as determined with dynamic light scattering. PI is the polydispersity index. ζ is the Zeta-Potential. Nanoemulsions carrying the same portion of PFC show a comparable size and size distribution when measured directly after preparation. Size and size distribution change during heat sterilization where those nanoemulsions without perfluorodecylbromide (PFDB) (23 and 63) grow more than their homologues with PFDB (20/3 and 60/3).</p><p>Initial dynamic light scattering analysis of nanoemulsions.</p

Nanoemulsion composition and indices.

<p>Nanoemulsion composition and indices.</p

Sample Cryo-TEM images of perfluorocarbon-nanoemulsions.

<p>(A) Image of a nanoemulsion containing 23% w/w perfluorooctylbromide, after heat sterilization. Nanoemulsion droplets appear as dark vesicles, liposomes are visible to a hugh number as smaller, light vesicles. Scale bar is 500 nm. (B) shows the same nanoemulsion after 50 weeks storage at 4°C. Though the scale bar is 1 μm in this image, increased size of droplets can easily be observed. The number of liposomes seems to be stepped up. In (C) a nanoemulsion containing 20% perfluorooctylbromide and 3% perfluorodecylbromide after heat sterilization is depicted. Though a huge number of liposomes can be detected, more and smaller nanoemulsion droplets are visible than compared to image (A). All samples were diluted in the same ratio with sample buffer.</p

Frequency of nanoemulsion droplet sizes in heat sterilized preparations.

<p>Data obtained from Cryo-TEM image analysis. Nanoemulsions without added perfluorodecylbromide (23 and 63) show a broader size distribution that is shifted to bigger droplets as compared to nanoemulsions containing 3% perfluorodecylbromide (20/3 and 60/3). This indicates a stabilizing effect of perfluorodecylbromide in heat sterilization.</p

Box plot diagrams revealing droplet size distribution of nanoemulsions.

<p>Box plots show the development of droplet sizes over storage time for four nanoemulsions. Boxes represent droplet sizes with a probability between 25 and 75%, the line ▬ inside the box is for the median size. Mean diameter is indicated with a bullet ● and whiskers are for a probability of 5 (┴) or 95 (┬) % respectively. An arrow pointing downwards (▼) indicates the 1% value whereas an arrow pointing upwards (▲) represents the 99% probability of particle diameter. (A) is the nanoemulsion containing 23% perfluorooctylbromide (23), (B) the nanoemulsion with 20% perfluorooctylbromide and 3% perfluorodecylbromide (20/3). (C) represents the nanoemulsion with 63% perfluorooctylbromide (63) and (D) the one with 60% perfluorooctylbromide and 3% perfluorodecylbromide (60/3). Nanoemulsions lacking perfluorodecylbromide (A and C) show a broader size distribution and bigger mean size than their comparative nanoemulsions with stabilizing perfluorodecylbromide (B and D).</p

Exosome-coated metal–organic framework nanoparticles: an efficient drug delivery platform

Drug delivery systems aim at a reduction of side effects in chemotherapy. This is achieved by encapsulation of drugs in nanocarriers followed by controlled release of these drugs at the site of the diseased tissue. Though inorganic or polymeric nanoparticles (NPs) are often used as nanocarriers,(1, 2) hybrid nanomaterials such as metal−organic framework (MOF) NPs have recently emerged as a valuable alternative.(3-6) They are synthesized from inorganic and organic building block units to create porous three-dimensional frameworks. Because of this building principle, the composition and structure of these materials are highly tunable.(7-10) Furthermore, both external and internal surfaces can be functionalized independently. With these properties, MOF NPs can be designed to fit the specific requirements of the desired application.(3, 11) For drug delivery purposes these so-called “design materials” have been synthesized with high porosity allowing for high drug loading capacities. They also have been designed to be biodegradable. Specifically, iron-based MOF NPs have attracted great attention. In addition to the above-mentioned properties, they can be detected via magnetic resonance imaging (MRI), rendering them an ideal platform for theranostics.(12-14) In our study, we focus on one of these iron-based MOFs, namely MIL-88A NPs, which are composed of iron(III) and fumaric acid.(15, 16) Both compounds can be found in the body and the NPs are reported to be nontoxic.(12) Additionally, MIL-88A NPs have been shown to efficiently host chemotherapeutic drugs.(12) Thus, they represent a promising nanocarrier