Biology subjects

Persson, L.

Publications and source records attributed to Persson, L..

3 recordsLinked to original sources

bioRxiv2024

Evaluation of Iron Oxide Nanoparticles for Lymph Node Detection with Magnetomotive Ultrasound- A Pilot Study in Rats

IntroductionThe inadequate detection of lymph node metastases by current imaging methods has led to overtreatment in rectal cancer. Magnetomotive ultrasound (MMUS) has the potential of being a more accurate diagnostic imaging method for lymph node metastases. This method is based on the detection of tissue movement that is induced by the vibration of iron oxide nanoparticles, caused by an external alternating magnetic field. This study investigated the suitability of the subcutaneous administration of two iron oxide nanoparticles--Ferrotran(R) and Magtrace(R)--and their distribution in lymph nodes, with regard to the possibility of identifying lymph node metastases in rectal cancer by MMUS. MethodsMale Sprague Dawley rats were injected subcutaneously with 10.7 mg Ferrotran(R) (n=9), 10.5 mg Magtrace(R) (n=9), or saline (n=3) dorsally at the root of the tail. On euthanization of the rats after 1, 5, and 24 hours, the proximal and distal lymph nodes were harvested and analyzed by histology [hematoxylin/eosin, Perls Prussian Blue (PPB)] and inductively coupled plasma-optical emission spectroscopy. The primary aim was to evaluate the distribution of the iron oxide nanoparticles throughout the lymphatic system; the general health of the rats after subcutaneous administration of these nanoparticles was also monitored. ResultsAt 1 hour after subcutaneous injection, Ferrotran(R) and Magtrace(R) accumulated in the proximal lymph nodes. After 24 hours, both particles had spread to distal lymph nodes, but only Ferrotran(R) reached the mesenteric and mandibular lymph nodes. In addition, Ferrotran(R) penetrated the lymph nodes more deeply than Magtrace(R) at 24 hours. No toxicity was observed with either nanoparticle. ConclusionAlthough both compounds disseminated well, Ferrotran(R) accumulated better and more rapidly in lymph nodes than Magtrace(R). Because accumulation and time are important parameters for imaging, our data indicate that Ferrotran(R) is a potentially more suitable particle for MMUS in clinical use.

biophysics↗

bioRxiv2019

Viscoadaptation controls intracellular reaction rates in response to heat and energy availability

Summary/AbstractCells must precisely orchestrate thousands of reactions in both time and space. Yet reaction kinetics are highly dependent on uncontrollable environmental conditions such as temperature. Here, we report a novel mechanism by which budding yeast influence reaction rates through adjustment of intracellular viscosity. This \"viscoadaptation\" is achieved by production of two carbohydrates, trehalose and glycogen, which combine to create a more viscous cellular environment in which biomolecules retain solubility. We demonstrate that viscoadaptation functions as both an acute response to temperature increase as well as a homeostatic mechanism, allowing cells grown at temperatures spanning from 22{degrees}C to 40{degrees}C to maintain equivalent rates of intracellular diffusion and diffusion-controlled chemical reactions. Multiple conditions that lower ATP trigger viscoadaptation, suggesting that viscoadaptation may be a general cellular response to low energy. Viscoadaptation reveals viscosity to be a tunable property of cells through which they can regulate diffusion-controlled processes dynamically in response to a changing environment.

cell biology↗

bioRxiv2018

Conjugation factors controlling F-plasmid antibiotic resistance transmission

The rapid horizontal transmission of many antibiotic resistance genes between bacterial host cells on conjugative plasmids is a major cause of the accelerating antibiotic resistance crisis. Preventing understanding and targeting conjugation, there currently are no experimental platforms for fast and cost-efficient screening of genetic effects on antibiotic resistance transmission by conjugation. We introduce a novel experimental framework to screen for conjugation based horizontal transmission of antibiotic resistance between >60.000 pairs of cell populations in parallel. Plasmid-carrying donor strains are constructed in high throughput. We then mix the resistance plasmid carrying donors with recipients in a design where only transconjugants can reproduce, measure growth in dense intervals and extract transmission times as the growth lag. As proof-of-principle, we exhaustively explored chromosomal genes controlling F plasmid donation within E. coli populations, by screening the Keio deletion collection at high replication. We recover all six known chromosomal gene mutants affecting conjugation and identify >50 novel factors, all of which diminish antibiotic resistance transmission. We verify 10 of the novel genes effects in a liquid mating assay. The new framework holds great potential for exhaustive disclosing of candidate targets for helper drugs that delay resistance development in patients and societies and improves the longevity of current and future antibiotics.

microbiology↗