Podocyte vascular endothelial growth factor (Vegf₁₆₄) overexpression causes severe nodular glomerulosclerosis in a mouse model of type 1 diabetes

AIMS/HYPOTHESIS

The pathogenic role of excessive vascular endothelial growth factor (VEGF)-A in diabetic nephropathy has not been defined. We sought to test whether increased podocyte VEGF-A signalling determines the severity of diabetic glomerulopathy.

METHODS

Podocyte-specific, doxycycline-inducible Vegf₁₆₄ (the most abundant Vegfa isoform) overexpressing adult transgenic mice were made diabetic with low doses of streptozotocin and examined 12 weeks after onset of diabetes. We studied diabetic and non-diabetic transgenic mice fed a standard or doxycycline-containing diet. VEGF-A and albuminuria were measured by ELISA, creatinine was measured by HPLC, renal morphology was examined by light and electron microscopy, and gene expression was assessed by quantitative PCR, immunoblotting and immunohistochemistry.

RESULTS

Podocyte Vegf₁₆₄ overexpression in our mouse model of diabetes resulted in advanced diabetic glomerulopathy, characterised by Kimmelstiel-Wilson-like nodular glomerulosclerosis, microaneurysms, mesangiolysis, glomerular basement membrane thickening, podocyte effacement and massive proteinuria associated with hyperfiltration. It also led to increased VEGF receptor 2 and semaphorin3a levels, as well as nephrin and matrix metalloproteinase-2 downregulation, whereas circulating VEGF-A levels were similar to those in control diabetic mice.

CONCLUSIONS/INTERPRETATION

Collectively, these data demonstrate that increased podocyte Vegf₁₆₄ signalling dramatically worsens diabetic nephropathy in a streptozotocin-induced mouse model of diabetes, resulting in nodular glomerulosclerosis and massive proteinuria. This suggests that local rather than systemic VEGF-A levels determine the severity of diabetic nephropathy and that semaphorin3a signalling and matrix metalloproteinase-2 dysregulation are mechanistically involved in severe diabetic glomerulopathy.

Advances in ecology and conservation of Hippocamelus species in South America

A symposium was held for the two South American deer of the genus Hippocamelus: the taruka, H. antisensis and the Patagonian huemul, H. bisulcus. The taruka is recognized as vulnerable and the huemul as endangered on the IUCN red list. To reverse the current trend and prevent further imminent declines, 13 recommendations were proposed. For taruka, national recovery plans should be developed and implemented in each country it inhabits, and hunting must be managed. For huemul’s lack of recovery, much still remains unknown about the causal factors and their overall significance: culpeo fox (Pseudalopex culpaeus) appear not to be an important mortality agent of heumul fawns, whereas habitat suitability may be the fundamental cause for the declines. Research should be conducted to better evaluate the interplay of threats and their relative importance.

Activated sludge model (ASM) based modelling of membrane bioreactor (MBR) processes: a critical review with special regard to MBR specificities

Membrane bioreactors (MBRs) have been increasingly employed for municipal and industrial wastewater treatment in the last decade. The efforts for modelling of such wastewater treatment systems have always targeted either the biological processes (treatment quality target) as well as the various aspects of engineering (cost effective design and operation). The development of Activated Sludge Models (ASM) was an important evolution in the modelling of Conventional Activated Sludge (CAS) processes and their use is now very well established. However, although they were initially developed to describe CAS processes, they have simply been transferred and applied to MBR processes. Recent studies on MBR biological processes have reported several crucial specificities: medium to very high sludge retention times, high mixed liquor concentration, accumulation of soluble microbial products (SMP) rejected by the membrane filtration step, and high aeration rates for scouring purposes. These aspects raise the question as to what extent the ASM framework is applicable to MBR processes. Several studies highlighting some of the aforementioned issues are scattered through the literature. Hence, through a concise and structured overview of the past developments and current state-of-the-art in biological modelling of MBR, this review explores ASM-based modelling applied to MBR processes. The work aims to synthesize previous studies and differentiates between unmodified and modified applications of ASM to MBR. Particular emphasis is placed on influent fractionation, biokinetics, and soluble microbial products (SMPs)/exo-polymeric substances (EPS) modelling, and suggestions are put forward as to good modelling practice with regard to MBR modelling both for end-users and academia. A last section highlights shortcomings and future needs for improved biological modelling of MBR processes.

Clinical benefit of lapatinib-based therapy in patients with HER2-positive breast tumors expressing p95HER2

1048

Background: Approximately 25% of HER2 overexpressing breast tumors express a truncated form of the receptor (p95HER2) that lacks the extracellular domain but retains kinase activity. p95HER2-positive tumors are associated with a worse prognosis and resistant to trastuzumab therapy. In preclinical models, lapatinib (L), a tyrosine kinase inhibitor of EGFR and HER2, is active in p95HER2 expressing tumors. The aim of this analysis was to test the hypothesis that benefit from L-based therapy is independent of p95HER2 expression in 2 clinical trials in patients (pts) with HER2-positive tumors treated with either L monotherapy (Study EGF20009 ) or L in combination with capecitabine (Study EGF100151). Methods: Pre-treatment tumor tissue from both trials (N=201) was analyzed for p95HER2 expression by immunofluorescence as previously described (Scaltriti M. et al, JNCI 2007). Expression of p95HER2 was correlated with clinical benefit rate (CBR: complete response [CR] + partial response [PR] + stable disease [SD] ≥ 24 weeks) and progression-free survival (PFS) using logistic regression and Cox-proportional hazard models. Results: 68/105 and an initial 72/96 tissue samples were evaluable for p95HER2 expression from studies EGF20009 and EGF100151, respectively. The Table summarizes the results from the L treated pts. The CBR and PFS in L treated pts were not significantly different between the p95HER2 subgroups. Expanded data for p95HER2 expression in additional EGF100151 tumor samples will be presented. Conclusions: L as a monotherapy or in combination with capecitabine has similar response activity in pts with p95HER2-positive and p95HER2-negative HER2-positive breast tumors.

[Table: see text]

[Table: see text]