Nanotechnology research has continued to garner interest and is investigated across a number of fields and industries, ranging from water treatment to clinical and biomedical applications. In biomedical research, for example, polymeric nanoparticles can be leveraged for controlled delivery of drugs and chemical compounds into cells. In cryobiological applications, polymeric nanoparticles can be utilized to deliver cryoprotectants (CPAs) and other protective agents, particularly those impermeable to the cell membrane, into cells to study their effects on cells during cooling down and warming back and at low temperatures. This perspective will discuss how polymeric nanoparticles have been used in cryobiology, with particular focus on how delivery systems have been specifically developed for low temperature applications and the potential for these systems going forward.
Amphotericin B (AmB) increases host resistance against several infectious agents and tumors. We evaluated its effect on infections with the helminth Schistosoma mansoni. A single dose of 500 microgram i.p. or 25 microgram i.v. increased resistance in mice to a challenge with 500 or 100 S. mansoni cercariae. Schistosomula recovery from the lungs, 5 days after challenge, was reduced 33 to 40%. Adult worm recovery 8 wk after infection was reduced 36 to 43%, AmB was effective in protecting mice when given from 9 days before until the day of cercarial challenge but was ineffective 2 wk before or at all intervals after S. mansoni infection. To examine the mechanism of this resistance, we obtained peritoneal exudate cells (PEC) from animals treated with AmB and assessed their ability to kill schistosomula, the migrating larval stage of the parasite. Killing by adherent PEC 1 or 2 days after AmB treatment was the same as that of resident macrophages from untreated animals. Adherent PEC from animals 3 to 7 days after AmB treatment showed enhanced killing of schistosomula (38.0 plus or minus 3.0% at day 4, which exceeded control of 8.1 plus or minus 4.0%, p less than 0.01). These PEC also displayed increased killing of Staphylococcus aureus. When AmB was added to cultures of resident peritoneal adherent cells from untreated mice at 0.5 microgram/ml to 2.0 microgram/ml (concentrations not toxic to the organism), schistosomula killing was increased 1- to 6- fold. These findings demonstrate activation of murine macrophages by AmB in vitro and in vivo, which results in greater killing of this multicellular parasite and potentially contributes to enhanced resistance to infection.
We have developed a method for using short (30-42 base pair) synthetic oligonucleotide DNA probes in Northern blot assays. The method involves labeling the probes to high specific activity, very stringent hybridization and wash conditions, and the presence of several inhibitors of nonspecific binding in the hybridization buffer. We have tested this method with several probes obtained from local and commercial sources. The results with every probe used were high signal-to-noise ratios in an exposure time range of 30 min to 7 days.
The effects of pertussis toxin and cholera toxin on early events of T lymphocyte activation were examined in the T lymphocyte cell line, Jurkat. Pertussis toxin treatment of these T cells increased inositol phosphates production and led to increases in intracellular free calcium concentration. These effects were produced by the isolated B (binding) subunit of pertussis toxin, alone. Inositol phosphates production resulting from perturbation of the T cell antigen receptor-CD3 complex by MAb was not affected by pertussis toxin treatment but was markedly inhibited by cholera toxin. This effect of cholera toxin paralleled elevations in cAMP content. However, forskolin, in concentrations equipotent for cAMP production, was a weaker inhibitor of inositol phosphates production. Cholera toxin inhibition of inositol phosphates production did not result from inhibition of baseline incorporation of inositol into phosphoinositide substrates of phospholipase C. These studies underline the complexity of toxin effects on cellular systems and suggest that other approaches will be required to implicate guanine nucleotide-binding regulatory proteins in control of the early events of T lymphocyte activation. However, the data presented here provide a molecular basis for the clinical observations of lymphocytosis and the in vitro observations of lymphocyte mitogenesis after pertussis toxin stimulation.
Type 1 diabetes is an autoimmune disease in which the immune system attacks insulin-producing beta cells of pancreatic islets. Type 1 diabetes can be treated with islet transplantation; however, patients must be administered immunosuppressants to prevent immune rejection of the transplanted islets if they are not autologous or not engineered with immune protection/isolation. To overcome biological barriers of islet transplantation, encapsulation strategies have been developed and robustly investigated. While islet encapsulation can prevent the need for immunosuppressants, these approaches have not shown much success in clinical trials due to a lack of long-term insulin production. Multiple engineering strategies have been used to improve encapsulation and post-transplantation islet survival. In addition, more efficient islet cryopreservation methods have been designed to facilitate the scaling-up of islet transplantation. Other islet sources have been identified including porcine islets and stem cell-derived islet-like aggregates. Overall, islet-laden capsule transplantation has greatly improved over the past 30 years and is moving toward becoming a clinically feasible treatment for type 1 diabetes.
