Isolated Lung Perfusion as an Adjuvant Treatment of Colorectal Cancer Lung Metastases: A Preclinical Study in a Pig Model

Background

The lung is a frequent site of colorectal cancer (CRC) metastases. After surgical resection, lung metastases recurrences have been related to the presence of micrometastases, potentially accessible to a high dose chemotherapy administered via adjuvant isolated lung perfusion (ILP). We sought to determine in vitro the most efficient drug when administered to CRC cell lines during a short exposure and in vivo its immediate and delayed tolerance when administered via ILP.

Methods

First, efficacy of various cytotoxic molecules against a panel of human CRC cell lines was tested in vitro using cytotoxic assay after a 30-minute exposure. Then, early (operative) and delayed (1 month) tolerance of two concentrations of the molecule administered via ILP was tested on 19 adult pigs using hemodynamic, biological and histological criteria.

Results

In vitro, gemcitabine (GEM) was the most efficient drug against selected CRC cell lines. In vivo, GEM was administered via ILP at regular (20 µg/ml) or high (100 µg/ml) concentrations. GEM administration was associated with transient and dose-dependant pulmonary vasoconstriction, leading to a voluntary decrease in pump inflow in order to maintain a stable pulmonary artery pressure. After this modulation, ILP using GEM was not associated with any systemic leak, systemic damage, and acute or delayed histological pulmonary toxicity. Pharmacokinetics studies revealed dose-dependant uptake associated with heterogenous distribution of the molecule into the lung parenchyma, and persistent cytotoxicity of venous effluent.

Conclusions

GEM is effective against CRC cells even after a short exposure. ILP with GEM is a safe and reproducible technique.     

Chemical modifications of imidazole-containing alkoxyamines increase C–ON bond homolysis rate: Effects on their cytotoxic properties in glioblastoma cells

Previously, we described alkoxyamines bearing a pyridine ring as new pro-drugs with low molecular weights and theranostic activity. Upon chemical stimulus, alkoxyamines undergo homolysis and release free radicals, which can, reportedly, enhance magnetic resonance imaging and trigger cancer cell death. In the present study, we describe the synthesis and the anti-cancer activity of sixteen novel alkoxyamines that contain an imidazole ring. Activation of the homolysis was conducted by protonation and/or methylation. These new molecules displayed cytotoxic activities towards human glioblastoma cell lines, including the U251-MG cells that are highly resistant to the conventional chemotherapeutic agent Temozolomide. We further showed that the biological activities of the alkoxyamines were not only related to their half-life times of homolysis. We lastly identified the alkoxyamine (RS/SR)-4a, with both a high antitumour activity and favourable logD_7.4 and pK_a values, which make it a robust candidate for blood-brain barrier penetrating therapeutics against brain neoplasia.     

Effects of dietary soybean lecithin on plasma lipid transport and hepatic cholesterol metabolism in rats

Dietary lecithin can stimulate bile formation and biliary lipid secretion, particularly cholesterol output in bile. Studies also suggested that the lecithin-rich diet might modify hepatic cholesterol homeostasis and lipoprotein metabolism. Therefore, we examined hepatic activities of 3-hydroxy-3 methylglutaryl coenzyme A reductase "HMG -CoA reductase", cholesterol 7 alpha-hydroxylase and acyl-CoA: cholesterol acyltransferase "ACAT" as well as plasma lipids and lipoprotein composition in rats fed diets enriched with 20% of soybean lecithin during 14 days. We also evaluated the content of hepatic canalicular membrane proteins involved in lipid transport to the bile (all P-glycoproteins as detected by the C 219 antibody and the sister of P-glycoprotein "spgp" or bile acid export pump) by Western blotting. As predicted, lecithin diet modified hepatic cholesterol homeostasis. The activity of hepatic HMG-CoA reductase and cholesterol 7 alpha-hydroxylase was enhanced by 30 and 12% respectively, while microsomal ACAT activity showed a dramatic decrease of 75%. As previously reported from ACAT inhibition, the plasma level and size of very low-density lipoprotein (VLDL) were significantly decreased and bile acid pool size and biliary lipid output were significantly increased. The canalicular membrane content of lipid transporters was not significantly affected by dietary lecithin. The current data on inhibition of ACAT activity and related metabolic effects by lecithin mimic the previously reported effects following drug-induced inhibition of ACAT activity, suggesting potential beneficial effects of dietary lecithin supplementation in vascular disease.     

Natural regulatory T cells control the development of atherosclerosis in mice

Atherosclerosis is an immunoinflammatory disease elicited by accumulation of lipids in the artery wall and leads to myocardial infarction and stroke. Here, we show that naturally arising CD4(+)CD25(+) regulatory T cells, which actively maintain immunological tolerance to self and nonself antigens, are powerful inhibitors of atherosclerosis in several mouse models. These results provide new insights into the immunopathogenesis of atherosclerosis and could lead to new therapeutic approaches that involve immune modulation using regulatory T cells.     

Physiology of maize II: Identification of physiological markers representative of the nitrogen status of maize (Zea mays) leaves during grain filling

To illustrate the development of the source-to-sink transition in maize leaves during the grain-filling period, an integrated physiological-agronomic approach is presented in this study. The evolution of physiological markers such as total leaf nitrogen (N), chlorophyll, soluble protein, amino acid and ammonium contents was monitored from silking to a period close to maturity in different leaf stages of three maize genotypes grown at high and low levels of N fertilization. In addition, the activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH), two enzymes known to play a direct or an indirect role during leaf N remobilization, were measured. In the three genotypes examined, we found that a general decrease of most metabolic and enzyme markers occurred during leaf ageing and that this decrease was enhanced when plants were N starved. In contrast, such variations were not observed between different sections of a single leaf even at an advanced stage of leaf senescence. We found that there is a strong correlation between total N, chlorophyll, soluble protein and GS activity, which is not dependent upon the N fertilization level, which indicates the N status of the plant, either in a single leaf or during ageing. In contrast, ammonium, amino acids and GDH activity were not subject to such variations, thus suggesting that they are indicators of the metabolic activity of the whole plant in response to the level of N fertilization. The use of these markers to predict the N status of maize as a function of both plant development and N availability is discussed.     

Evolution in heterogeneous environments: between soft and hard selection

Since their first formulations about half a century ago, the soft and hard selection models have become classical frameworks to study selection in subdivided populations. These models differ in the timing of density regulation and represent two extreme types of selection: density- and frequency-dependent selection (soft) and density- and frequency-independent selection (hard). Yet only few attempts have been made so far to model intermediate scenarios. Here, we design a model where migration may happen twice during the life cycle: before density regulation with probability d(J) (juvenile migration) and after density regulation with probability d(A) (adult migration). In the first step, we analyze the conditions for the coexistence of two specialists. We find that coexistence is possible under a large range of selection types, even when environmental heterogeneity is low. Then, we investigate the different possible outcomes obtained through gradual evolution. We show that polymorphism is more likely to evolve when the trade-off is weak, environmental heterogeneity is high, migration is low, and in particular when juvenile migration is low relative to adult migration, because the timing of migration affects the magnitude of frequency-dependent selection relative to gene flow. This model may provide a more general theoretical framework to experimentally study evolution in heterogeneous environments.     

Compartment-Specific Biosensors Reveal a Complementary Subcellular Distribution of Bioactive Furin and PC7

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