Mojca Krzan

Surface modified magnetic nanoparticles for immuno-gene therapy of murine mammary adenocarcinoma

Cancer immuno-gene therapy is an introduction of nucleic acids encoding immunostimulatory proteins, such as cytokine interleukin 12 (IL-12), into somatic cells to stimulate an immune response against a tumor. Various methods can be used for the introduction of nucleic acids into cells; magnetofection involves binding of nucleic acids to magnetic nanoparticles with subsequent exposure to an external magnetic field. Here we show that surface modified superparamagnetic iron oxide nanoparticles (SPIONs) with a combination of polyacrylic acid (PAA) and polyethylenimine (PEI) (SPIONs-PAA-PEI) proved to be safe and effective for magnetofection of cells and tumors in mice. Magnetofection of cells with plasmid DNA encoding reporter gene using SPIONs-PAA-PEI was superior in transfection efficiency to commercially available SPIONs. Magnetofection of murine mammary adenocarcinoma with plasmid DNA encoding IL-12 using SPIONs-PAA-PEI resulted in significant antitumor effect and could be further refined for cancer immuno-gene therapy.

Controlled systemic release of interleukin-12 after gene electrotransfer to muscle for cancer gene therapy alone or in combination with ionizing radiation in murine sarcomas.

The present study aimed to evaluate the antitumor effectiveness of systemic interleukin (IL)‐12 gene therapy in murine sarcoma models, and to evaluate its interaction with the irradiation of tumors and metastases. To avoid toxic side‐effects of IL‐12 gene therapy, the objective was to achieve the controlled release of IL‐12 after intramuscular gene electrotransfer.

The prevalence and pattern of pharmaceutical and excipient exposure in a neonatal unit in Slovenia

Abstract Objective: Because of the restraints on conducting studies on pharmaceutical use in sick newborns, many drugs are used off-label in this population. Moreover, industrially manufactured pharmaceuticals may contain different excipients, which may be either untested or not licensed for use in neonates. The aim of our study was to determine the prevalence and pattern of pharmaceutical and excipient exposure in newborns hospitalized at the Department of Neonatology, Ljubljana, Slovenia. Methods: A longitudinal prospective cross-sectional study was performed during a one-month period and included all hospitalized neonates. Route of administration, site of action, type of manufacture, licensing status, type and concentrations of excipients for all pharmaceuticals given to the neonates were determined. Results: Twenty seven different pharmaceutical preparations were prescribed to a total of 48 hospitalized newborns. In most cases, newborns were prescribed various pharmaceuticals that were not approved for use in this population. Newborns were exposed to 60 different excipients in industrially manufactured pharmaceutical preparations. More than half of the received pharmaceuticals contained potentially harmful and harmful excipients. Conclusions: Two-thirds of pharmaceutical preparations for neonates were used off-label. Newborns receive more auxiliary substances, which may be unsuitable for this age group and may even be toxic to them, via industrially manufactured pharmaceuticals.

Histamine receptors in the heart—Molecular characteristics, physiology and pharmacology

Histamine is a normal constituent of mammalian heart. It affects cardiac function mainly through stimulating histamine H1- and H2-receptor subtypes.The simultaneous activation of H1- and H2-receptors in the heart results in: a positive inotropic and chronotropic effect, a negative dromotropic effect, increased automaticity and increased coronary blood flow.H1- and H2-receptors have already been cloned from different, but not yet from cardiac, tissue. They are two independent molecular entities differing in the length of their amino acid sequence, pathways of transmembrane and intracellular signalling, characteristics of their binding sites and selectivity for the specific agonists and/or antagonists. Our results of radioligand binding studies show the presence in the heart of a high-affinity (KD 0.4 nmol/L andBmax 100 fmol/mg of protein) and a low-affinity (KD 4.5 nmol/L,Bmax 466 fmol/mg of protein) H1-receptor-binding site and only a single population of less-abundant high-affinity H2-receptor binding sites (KD 1.0 nmol/L andBmax 27 fmol/mg of protein).The role of the histamine in cardiac pathophysiology is well established but the physiological role is unclear. The only proposed physiological role of histamine in the heart is the modulation of noradrenaline release from sympathetic nerve terminals, where H3-receptor subtypes might be involved.

Regional Characteristics of Histamine Uptake into Neonatal Rat Astrocytes

Histaminergic signalling constitutes an attractive target for treatment of neuropsychiatric disorders. One obstacle to developing new pharmacological options has been failure to identify putative specific histamine transporter responsible for histamine clearance. Although high-affinity histamine uptake was detected in neonatal cortical astrocytes, its existence in other brain regions remains largely unexplored. We investigated whether cerebellar and striatal astrocytes participate in histamine clearance and evaluated the role of organic cation transporters (OCT) in astroglial histamine transport. Kinetic and pharmacological characteristics of histamine transport were determined in cultured astrocytes derived from neonatal rat cerebellum, striatum and cerebral cortex. As well as astrocytes of cortical origin, cultured striatal and cerebellar astrocytes displayed temperature-sensitive, high-affinity histamine uptake. Exposure to ouabain or Na+-free medium, supplemented with choline chloride markedly depressed histamine transport in cortical astrocytes. Conversely, histamine uptake in striatal and cortical astrocytes was ouabain-resistant and was only partially diminished during incubation in the absence of Na+. Also, histamine uptake remained unaltered upon exposure to OCT inhibitor corticosterone, although OCTs were expressed in cultured astrocytes. Finally, histamine transport in cerebellar and striatal astrocytes was not sensitive to antidepressants. Despite common characteristics, cerebellar astrocytes had lower affinity, but markedly higher transport capacity for histamine compared to striatal astrocytes. Collectively, we provide evidence to suggest that cerebellar, striatal as well as cortical astrocytes possess saturable histamine uptake systems, which are not operated by OCTs. In addition, our data indicate that Na+-independent histamine carrier predominates in cerebellar and striatal astrocytes, whereas Na+-dependent transporter underlies histamine uptake in cortical astrocytes. Our findings implicate a role for histamine transporters in regulation of extracellular histamine concentration in cerebellum and striatum. Inhibition of histamine uptake might represent a viable option to modulate histaminergic neurotransmission.

Efficiency of electrochemotherapy with reduced bleomycin dose in the treatment of nonmelanoma head and neck skin cancer: Preliminary results

In the present study, effectiveness of electrochemotherapy was compared in patients with nonmelanoma skin cancer (NMSC) of the head and neck using standard and reduced doses of bleomycin.

Vascularization of the tumours affects the pharmacokinetics of bleomycin and the effectiveness of electrochemotherapy

Pre‐clinical and clinical data indicate differences in the responses of melanoma and carcinoma tumours to electrochemotherapy. The purpose of this study was to investigate the origin of this difference, whether it is due to the intrinsic difference in tumour cell susceptibility to the chemotherapeutic, or due to the tumour micro‐environment. For this purpose, we performed a pre‐clinical study in B16F1 melanoma and TS/A carcinoma tumours in mice, in which the antitumour effectiveness of electrochemotherapy with bleomycin, the intrinsic sensitivity of tumour cells in vitro, the pharmacokinetics of bleomycin in plasma and tumours, and the vascularization of tumours in vivo were evaluated. The results of the treatment show that carcinoma was significantly more responsive to electrochemotherapy than melanoma. This effect cannot be ascribed to the intrinsic sensitivity of these cells, as melanoma cells were more sensitive than carcinoma cells in vitro. The difference in responses could be ascribed to differences in the pharmacokinetics of bleomycin; at the time of electroporation in carcinomas, more bleomycin was accumulated. This effect could be due to differences in tumour vascularization, as carcinoma tumours had numerous well‐distributed, small blood vessels, while melanomas were less vascularized, exhibiting predominantly larger vessels. In conclusion, this study provides evidence on the importance of the tumour micro‐environment, particularly the tumour vasculature, in the responses of the tumours to bleomycin electrochemotherapy. Vasculature is important for the pharmacokinetics of bleomycin, influencing drug accumulation and drug distribution in tumours, and might be used as a predictive factor for the tumour response to electrochemotherapy.