Comparative Cardiac Toxicity of Anthracyclines In Vitro and In Vivo in the Mouse

Purpose

The antineoplastic efficacy of anthracyclines is limited by their cardiac toxicity. In this study, we evaluated the toxicity of doxorubicin, non-pegylated liposomal-delivered doxorubicin, and epirubicin in HL-1 adult cardiomyocytes in culture as well as in the mouse in vivo.

Methods

The cardiomyocytes were incubated with the three anthracyclines (1 µM) to assess reactive oxygen generation, DNA damage and apoptotic cell death. CF-1 mice (10/group) received doxorubicin, epirubicin or non-pegylated liposomal-doxorubicin (10 mg/kg) and cardiac function was monitored by Doppler echocardiography to measure left ventricular ejection fraction (LVEF), heart rate (HR) and cardiac output (CO) both prior to and 10 days after drug treatment.

Results

In HL-1 cells, non-pegylated liposomal-doxorubicin generated significantly less reactive oxygen species (ROS), as well as less DNA damage and apoptosis activation when compared with doxorubicin and epirubicin. Cultured breast tumor cells showed similar sensitivity to the three anthracyclines. In the healthy mouse, non-pegylated liposomal doxorubicin showed a minimal and non-significant decrease in LVEF with no change in HR or CO, compared to doxorubicin and epirubicin.

Conclusion

This study provides evidence for reduced cardiac toxicity of non-pegylated-liposomal doxorubicin characterized by attenuation of ROS generation, DNA damage and apoptosis in comparison to epirubicin and doxorubicin.     

Cancer incidence and mortality in people aged less than 75 years: Changes in Australia over the period 1987–2007

BackgroundAustralia has one of the highest rates of cancer incidence worldwide and, despite improving survival, cancer continues to be a major public health problem. Our aim was to provide simple summary measures of changes in cancer mortality and incidence in Australia so that progress and areas for improvement in cancer control can be identified.MethodsWe used national data on cancer deaths and newly registered cancer cases and compared expected and observed numbers of deaths and cases diagnosed in 2007. The expected numbers were obtained by applying 1987 age–sex specific rates (average of 1986–1988) directly to the 2007 population. The observed numbers of deaths and incident cases were calculated for 2007 (average of 2006–2008). We limited the analyses to people aged less than 75 years.ResultsThere was a 28% fall in cancer mortality (7827 fewer deaths in 2007 vs. 1987) and a 21% increase in new cancer diagnoses (13,012 more diagnosed cases in 2007). The greatest reductions in deaths were for cancers of the lung in males (?2259), bowel (?1797), breast (?773) and stomach (?577). Other notable falls were for cancers of the prostate (?295), cervix (?242) and non-Hodgkin lymphoma (?240). Only small or no changes occurred in mortality for cancers of the lung (female only), pancreas, brain and related, oesophagus and thyroid, with an increase in liver cancer (267). Cancer types that showed the greatest increase in incident cases were cancers of the prostate (10,245), breast (2736), other cancers (1353), melanoma (1138) and thyroid (1107), while falls were seen for cancers of the lung (?1705), bladder (?1110) and unknown primary (?904).ConclusionsThe reduction in mortality indicates that prevention strategies, improvements in cancer treatment, and screening programmes have made significant contributions to cancer control in Australia since 1987. The rise in incidence is partly due to diagnoses being brought forward by technological improvements and increased coverage of screening and early diagnostic testing.     

Genomic landscape of rat strain and substrain variation

Background

Since the completion of the rat reference genome in 2003, whole-genome sequencing data from more than 40 rat strains have become available. These data represent the broad range of strains that are used in rat research including commonly used substrains. Currently, this wealth of information cannot be used to its full extent, because the variety of different variant calling algorithms employed by different groups impairs comparison between strains. In addition, all rat whole genome sequencing studies to date used an outdated reference genome for analysis (RGSC3.4 released in 2004).

Results

Here we present a comprehensive, multi-sample and uniformly called set of genetic variants in 40 rat strains, including 19 substrains. We reanalyzed all primary data using a recent version of the rat reference assembly (RGSC5.0 released in 2012) and identified over 12 million genomic variants (SNVs, indels and structural variants) among the 40 strains. 28,318 SNVs are specific to individual substrains, which may be explained by introgression from other unsequenced strains and ongoing evolution by genetic drift. Substrain SNVs may have a larger predicted functional impact compared to older shared SNVs.

Conclusions

In summary we present a comprehensive catalog of uniformly analyzed genetic variants among 40 widely used rat inbred strains based on the RGSC5.0 assembly. This represents a valuable resource, which will facilitate rat functional genomic research. In line with previous observations, our genome-wide analyses do not show evidence for contribution of multiple ancestral founder rat subspecies to the currently used rat inbred strains, as is the case for mouse. In addition, we find that the degree of substrain variation is highly variable between strains, which is of importance for the correct interpretation of experimental data from different labs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1594-1) contains supplementary material, which is available to authorized users.     

alpha-Isopropylmalate, a leucine biosynthesis intermediate in yeast, is transported by the mitochondrial oxalacetate carrier

In Saccharomyces cerevisiae, alpha-isopropylmalate (alpha-IPM), which is produced in mitochondria, must be exported to the cytosol where it is required for leucine biosynthesis. Recombinant and reconstituted mitochondrial oxalacetate carrier (Oac1p) efficiently transported alpha-IPM in addition to its known substrates oxalacetate, sulfate, and malonate and in contrast to other di- and tricarboxylate transporters as well as the previously proposed alpha-IPM transporter. Transport was saturable with a half-saturation constant of 75 +/- 4 microm for alpha-IPM and 0.31 +/- 0.04 mm for beta-IPM and was inhibited by the substrates of Oac1p. Though not transported, alpha-ketoisocaproate, the immediate precursor of leucine in the biosynthetic pathway, inhibited Oac1p activity competitively. In contrast, leucine, alpha-ketoisovalerate, valine, and isoleucine neither inhibited nor were transported by Oac1p. Consistent with the function of Oac1p as an alpha-IPM transporter, cells lacking the gene for this carrier required leucine for optimal growth on fermentable carbon sources. Single deletions of other mitochondrial carrier genes or of LEU4, which is the only other enzyme that can provide the cytosol with alpha-IPM (in addition to Oac1p) exhibited no growth defect, whereas the double mutant DeltaOAC1DeltaLEU4 did not grow at all on fermentable substrates in the absence of leucine. The lack of growth of DeltaOAC1DeltaLEU4 cells was partially restored by adding the leucine biosynthetic cytosolic intermediates alpha-ketoisocaproate and alpha-IPM to these cells as well as by complementing them with one of the two unknown human mitochondrial carriers SLC25A34 and SLC25A35. Oac1p is important for leucine biosynthesis on fermentable carbon sources catalyzing the export of alpha-IPM, probably in exchange for oxalacetate.     

Liver autofluorescence properties in animal model under altered nutritional conditions

Autofluorescence spectroscopy is a promising and powerful approach for an in vivo, real time characterization of liver functional properties. In this work, preliminary results on the dependence of liver autofluorescence parameters on the nutritional status are reported, with particular attention to vitamin A and lipid accumulation in liver tissue. Normally fed and 24 h starving rats were used as animal models. Histochemical and autofluorescence analysis showed that lipids and vitamin A colocalize in the liver parenchyma. Fasting condition results in a parallel increase in both lipids and vitamin A. Autofluorescence imaging and microspectrofluorometric analysis carried out on unfixed, unstained tissue sections under 366 nm excitation, evidenced differences in both spectral shape and response to continuous irradiation between liver biopsies from fed and starving rats. As to photobleaching, in particular, fitting analysis evidenced a reduction of about 85% of the signal attributable solely to vitamin A during the first 10 s of irradiation. The tissue whole emission measured in fed and starving rat livers exhibited reductions of about 35% and 52%, respectively, that are closely related to vitamin A contents. The findings open interesting perspectives for the set up of an in situ, real time diagnostic procedure for the assessment of liver lipid accumulation, exploiting the photophysical properties of vitamin A.     

Development of Nutritionally Enhanced Tortillas

Large interest has recently risen in the development of “functional” foods, products that may provide a health benefit beyond the traditional nutrients. Foods rich in antioxidants and, simultaneously, characterized by a low glycemic index (GI), can reduce, through a double mechanism, the risk of increased postprandial oxidative stress, which is one of the constituent of the onset of several chronic diseases. Nutritionally enhanced tortillas were therefore developed by incorporating ingredients with well-documented nutritional functionality (carrots, soy, and wholemeal kamut) in a standard wheat tortillas formulation, in an attempt to create low GI and antioxidant-rich products while preserving sensory acceptability and physico-chemical properties. Five tortilla prototypes were developed and characterized for sensory acceptability, textural attributes, color, total antioxidant capacity, and in vivo GI. The simultaneous combination of carrot juice, soy, and wholemeal kamut resulted in a very interesting product that was not only the most acceptable by the consumers (although slightly harder than the standard control) but also showed the lowest GI and was relatively high in total antioxidant capacity. This work was presented at the 2nd International Symposium on: Delivery of Functionality in Complex Food Systems, Amherst, MA, USA, October 8–10, 2007.     

Attenuated AMPA Receptor Expression Allows Glioblastoma Cell Survival in Glutamate-Rich Environment

Background

Glioblastoma multiforme (GBM) cells secrete large amounts of glutamate that can trigger AMPA-type glutamate receptors (AMPARs). This commonly results in Na⁺ and Ca²⁺-permeability and thereby in excitotoxic cell death of the surrounding neurons. Here we investigated how the GBM cells themselves survive in a glutamate-rich environment.

Methods and Findings

In silico analysis of published reports shows down-regulation of all ionotropic glutamate receptors in GBM as compared to normal brain. In vitro, in all GBM samples tested, mRNA expression of AMPAR subunit GluR1, 2 and 4 was relatively low compared to adult and fetal total brain mRNA and adult cerebellum mRNA. These findings were in line with primary GBM samples, in which protein expression patterns were down-regulated as compared to the normal tissue. Furthermore, mislocalized expression of these receptors was found. Sequence analysis of GluR2 RNA in primary and established GBM cell lines showed that the GluR2 subunit was found to be partly unedited.

Conclusions

Together with the lack of functional effect of AMPAR inhibition by NBQX our results suggest that down-regulation and afunctionality of AMPARs, enable GBM cells to survive in a high glutamate environment without going into excitotoxic cell death themselves. It can be speculated that specific AMPA receptor inhibitors may protect normal neurons against the high glutamate microenvironment of GBM tumors.     

Type 4 pili are dispensable for biofilm development in the cyanobacterium Synechococcus elongatus

The hair‐like cell appendages denoted as type IV pili are crucial for biofilm formation in diverse eubacteria. The protein complex responsible for type IV pilus assembly is homologous with the type II protein secretion complex. In the cyanobacterium Synechococcus elongatus PCC 7942, the gene Synpcc7942_2071 encodes an ATPase homologue of type II/type IV systems. Here, we report that inactivation of Synpcc7942_2071 strongly affected the suite of proteins present in the extracellular milieu (exo‐proteome) and eliminated pili observable by electron microscopy. These results support a role for this gene product in protein secretion as well as in pili formation. As we previously reported, inactivation of Synpcc7942_2071 enables biofilm formation and suppresses the planktonic growth of S. elongatus. Thus, pili are dispensable for biofilm development in this cyanobacterium, in contrast to their biofilm‐promoting function in type IV pili‐producing heterotrophic bacteria. Nevertheless, pili removal is not required for biofilm formation as evident by a piliated mutant of S. elongatus that develops biofilms. We show that adhesion and timing of biofilm development differ between the piliated and non‐piliated strains. The study demonstrates key differences in the process of biofilm formation between cyanobacteria and well‐studied type IV pili‐producing heterotrophic bacteria.