Neurotrophins and their receptors in breast cancer

Growth factors of the neurotrophin family and their receptors have been mainly studied in the nervous system, but they are also expressed in carcinomas, and in breast cancer they significantly impact tumor cell growth and metastasis through various signaling pathways. Nerve growth factor and its precursor proNGF, brain-derived neurotrophic factor and neurotrophin-4/5 stimulate breast cancer cells through an autocrine loop involving the tyrosine kinase receptors TrkA, TrkB as well as its truncated form TrkB.T1 and the p75^NTR death receptor. Preclinical studies have shown that targeting neurotrophins and their receptors induce an inhibition of breast cancer cell survival, proliferation and invasion. Furthermore, targeting neurotrophins may also decrease tumor-induced cancer pain and this additional effect further strengthens their clinical relevance.     

Secretive bacterial pathogens and the secretory pathway

Eukaryotic cells possess two extensive endomembrane systems, each consisting of several sub-compartments connected by vesicular trafficking. One of these systems, the endocytic pathway, serves incoming traffic, and the other system, the secretory pathway (SP), is responsible for surface-bound traffic of intracellularly formed vesicles. Compartments derived of either system can be colonized by intracellular pathogens. In this review, we discuss the interactions between the SP and prominent intracellular bacterial pathogens of the genera Legionella, Brucella, Chlamydia and Salmonella. We emphasize secreted bacterial effector proteins, which directly manipulate host components of this pathway.     

Regulation of hepatic mitochondrial metabolism in response to a high fat diet: a longitudinal study in rats

Mitochondrial dysfunctions have been detected in non-alcoholic steatohepatitis, but less information exists regarding adaptation of mitochondrial function during the initiation of hepatic steatosis. This study aimed to determine in rat liver the sequence of mitochondrial and metabolic adaptations occurring during the first 8 weeks of a moderate high fat diet (HFD). Sprague-Dawley rats were fed a HFD during 2, 4, and 8 weeks. Mitochondrial oxygen consumption, respiratory chain complexes activity, and oxidative phosphorylation efficiency were assessed in isolated liver mitochondria. Gene expression related to fat metabolism and mitochondrial biogenesis were determined. Results were compared to data collected in a group of rats sacrificed before starting the HFD feeding. After 2 and 4 weeks of HFD, there was a development of fatty liver and a concomitant increase the expression of mitochondrial glycerol-3-phosphate acyltransferase (mtGPAT) and peroxisome proliferator-activated receptor γ. Higher serum β-hydroxybutyrate levels and enhanced hepatic pyruvate dehydrogenase kinase 4 expression suggested increased fatty acid oxidation. However, mitochondrial respiration and respiratory chain activity were normal. After 8 weeks of HFD, lower accumulation of liver triglycerides was associated with reduced expression of mtGPAT. At this time, oxygen consumption with palmitoyl-L: -carnitine was decreased whereas oxidative phosphorylation efficiency (ATP/O) with succinate was enhanced. Hepatic levels of mtDNA were unchanged whatever the time points. This longitudinal study in rats fed a HFD showed that hepatic lipid homeostasis and mitochondrial function can adapt to face the increase in fatty acid availability.     

A NanoDrop-based method for rapid determination of viability decline in suspension cultures of animal cells

We describe a rapid method for monitoring the cell growth and decline phases in suspension cultures of animal cells. During the cell growth phase, ultraviolet (UV)-absorbing components in the medium are consumed, but at later times as cells begin to die, UV-absorbing molecules such as proteins are released into the medium. Measuring the absorbance at 280 nm (A₂₈₀) with a NanoDrop spectrophotometer, an inverse correlation between the onset of the cell decline phase and A₂₈₀ was observed. This simple method can be applied to quickly determine the beginning of the decline phase of cultures of mammalian and insect cells in suspension.     

Episodic recruitment of the seedling banks in balsam fir and white spruce

• Premise of the study: In ecosystems where seed production is low and masting years are sporadic, or with species that have short-lived seeds, regeneration is assured by seedling banks rather than seed banks. Seedling establishment and survival play a critical role in determining the composition of these plant communities by supplying new individuals for their maintenance. Seedling emergence and mortality were investigated to test the hypothesis that recruitment into the seedling bank is periodic. • Materials and methods: Seed production and seedling emergence and survival was monitored during 1994-2007 in balsam fir (Abies balsamea) and white spruce (Picea glauca) in four pristine stands of the boreal forest of Quebec, Canada. Measurements were collected twice per month by sampling one permanent plot of 20 × 20 m per stand. • Key results: Seed-rain abundance reached 9 × 10³ seeds m⁻² year⁻¹, and was characterized by synchronous sequences of low and high seed production. New seedlings appeared only during the year following a seed production of at least 1 × 10³ and 1.5 × 10² seeds m⁻² year⁻¹ for balsam fir and white spruce, respectively. Seedlings emerged in July and survived 34-52 d on average, with balsam fir showing a longer lifespan and lower mortality, although 85–99% of seedlings died before completing one year of life. • Conclusions: The emergence of young seedlings was coupled with massive seed rains, which allowed synchronous replenishment of the seedling banks among stands and species, and generated different cohorts, yielding a discontinuous age structure.     

Understanding the central role of citrate in the metabolism of cancer cells

Cancers cells strongly stimulate glycolysis and glutaminolysis for their biosynthesis. Pyruvate derived from glucose is preferentially diverted towards the production of lactic acid (Warburg effect). Citrate censors ATP production and controls strategic enzymes of anabolic and catabolic pathways through feedback reactions. Mitochondrial citrate diffuses in the cytosol to restore oxaloacetate and acetyl-CoA. Whereas acetyl-CoA serves de novo lipid synthesis and histone acetylation, OAA is derived towards lactate production via pyruvate and / or a vicious cycle reforming mitochondrial citrate. This cycle allows cancer cells to burn their host's lipid and protein reserves in order to sustain their own biosynthesis pathways. In vitro, citrate has demonstrated anti-cancer properties when administered in excess, sensitizing cancer cells to chemotherapy. Understanding its central role is of particular relevance for the development of new strategies for counteracting cancer cell proliferation and overcoming chemoresistance.     

Emergency treatment of a ruptured huge omphalocele by simple suture of its membrane

Background

Emergency repair of incarcerated incisional hernia with associated bowel obstruction in potentially or contaminated field is technically challenging due to edematous, inflamed and friable tissues with occasional need for concurrent bowel resection and carries high rates of post-operative infectious complications. The aim of this study was to retrospectively assess the wound related morbidity of use of permanent prosthetic mesh in emergency repair of incarcerated incisional hernia with associated bowel obstruction. We also describe a new technique of leaving the mesh exposed to heal by secondary intention with granulation tissue.

Methods

Between 2000 and 2010 a total of 60 patients underwent emergency surgery for incarcerated incisional hernia with associated bowel obstruction with placement of permanent prosthetic mesh. The wound was closed after hernia repair in 55 patients while it was left open to granulate in 5 patients.

Results

In the group of patients with primary wound closure, 11 patients developed superficial surgical site infection, 5 developed deep wound infection and one patient had cellulitis. These patients were treated with wound debridement and antibiotics. Mesh removal was required in one patient. There were no infections in the group of patients who had their surgical wounds left open. One patient in this group died on the fifth postoperative day from septicemia.

Conclusion

Use of permanent prosthetic mesh in emergency repair of incarcerated incisional hernia with associated bowel obstruction. in contaminated field is associated with high risk of wound infection.     

Identification of naturally processed hepatitis C virus-derived major histocompatibility complex class I ligands

Fine mapping of human cytotoxic T lymphocyte (CTL) responses against hepatitis C virus (HCV) is based on external loading of target cells with synthetic peptides which are either derived from prediction algorithms or from overlapping peptide libraries. These strategies do not address putative host and viral mechanisms which may alter processing as well as presentation of CTL epitopes. Therefore, the aim of this proof-of-concept study was to identify naturally processed HCV-derived major histocompatibility complex (MHC) class I ligands. To this end, continuous human cell lines were engineered to inducibly express HCV proteins and to constitutively express high levels of functional HLA-A2. These cell lines were recognized in an HLA-A2-restricted manner by HCV-specific CTLs. Ligands eluted from HLA-A2 molecules isolated from large-scale cultures of these cell lines were separated by high performance liquid chromatography and further analyzed by electrospray ionization quadrupole time of flight mass spectrometry (MS)/tandem MS. These analyses allowed the identification of two HLA-A2-restricted epitopes derived from HCV nonstructural proteins (NS) 3 and 5B (NS3_1406–1415 and NS5B_2594–2602). In conclusion, we describe a general strategy that may be useful to investigate HCV pathogenesis and may contribute to the development of preventive and therapeutic vaccines in the future.     

Angiostatic kinase inhibitors to sustain photodynamic angio-occlusion

Targeted angiostatic therapy receives major attention for the treatment of cancer and exudative age‐related macular degeneration (AMD). Photodynamic therapy (PDT) has been used as an effective clinical approach for these diseases. As PDT can cause an angiogenic response in the treated tissue, combination of PDT with anti‐angiogenic compounds should lead to improved therapy. This study was undertaken to test the clinically used small molecule kinase inhibitors Nexavar® (sorafenib), Tarceva® (erlotinib) and Sutent® (sunitinib) for this purpose, and to compare the results to the combination of Visudyne®‐PDT with Avastin® (bevacizumab) treatment. When topically applied to the chicken chorioallantoic membrane at embryo development day (EDD) 7, a clear inhibition of blood vessel development was observed, with sorafenib being most efficient. To investigate the combination with phototherapy, Visudyne®‐PDT was first applied on EDD11 to close all <100 μm vessels. Application of angiostatics after PDT resulted in a significant decrease in vessel regrowth in terms of reduced vessel density and number of branching points/mm². As the 50% effective dose (ED50) for all compounds was approximately 10‐fold lower, Sorafenib outperformed the other compounds. In vitro, all kinase inhibitors decreased the viability of human umbilical vein endothelial cells. Sunitinib convincingly inhibited the in vitro migration of endothelial cells. These results suggest the therapeutic potential of these compounds for application in combination with PDT in anti‐cancer approaches, and possibly also in the treatment of other diseases where angiogenesis plays an important role.     

Seawater temperature, Gambierdiscus spp. variability and incidence of ciguatera poisoning in French Polynesia

In the context of global warming and climate change, ciguatera disease is put forward as an indicator of environmental disturbance. However, to validate this indicator, some unknown parameters such as the delay between environmental perturbation and outbreaks of ciguatera need to be investigated. The main goal of this study was to investigate the temporal link between the growth of Gambierdiscus spp., and one of its influencing factors and the declared cases of ciguatera disease in humans. Algal cell density and seawater temperature (SWT) were recorded monthly from February 1993 to December 2001 on the Atimaono barrier reef of Tahiti Island. Reports of ciguatera cases were obtained from three community health clinics near the study sites. The autoregressive integrated moving average model (ARIMA) shows: (1) SWT were positively associated with Gambierdiscus spp. growth at a lagtime of 13 and 17 months (p < 0.001); (2) Gambierdiscus spp. growth measured at a given time is related to a peak number of cases of ciguatera recorded 3 months after peak densities of this dinoflagellate (p < 0.001). These results allow the construction of a predictive model of the temporal link between ciguatera disease in humans and its etiologic agent: Gambierdiscus spp. This model constructed by using 1993–1999 data, then validated by 2000–2001 data, demonstrates an appreciable ability to predict changes in the incidence of ciguatera disease following algae blooms.