Comparative compositional analysis of cassava brown streak disease resistant 4046 cassava and its non-transgenic parental cultivar

Compositional analysis is an important component of an integrated comparative approach to assessing the food and feed safety of new crops developed using biotechnology. As part of the safety assessment of cassava brown streak disease resistant 4046 cassava, a comprehensive assessment of proximates, minerals, amino acids, fatty acids, vitamins, anti-nutrients, and secondary metabolites was performed on leaf and storage root samples of 4046 cassava and its non-transgenic parental control, TME 204, collected from confined field trials in Kenya and Uganda over two successive cropping cycles. Among the 100 compositional components that were assessed in samples of 4046 and control TME 204 cassava roots (47 components) and leaves (53 components), there were no nutritionally relevant differences noted. Although there were statistically significant differences between the transgenic and control samples for some parameters, in most cases the magnitudes of these differences were small (<20%), and in every case where comparative literature data were available, the mean values for 4046 and control cassava samples were within the range of normal variation reported for the compositional component in question. Overall, no consistent patterns emerged to suggest that biologically meaningful adverse changes in the composition or nutritive value of the leaves or storage roots occurred as an unintended or unexpected consequence of the genetic modification resulting in 4046 cassava. The data presented here provide convincing evidence of the safety of 4046 cassava with respect to its biochemical composition for food and feed, and it could be considered as safe as its non-transgenic control.

A Mitochondrial Role of SV2a Protein in Aging and Alzheimer's Disease: Studies with Levetiracetam

Aberrant neuronal network activity associated with neuronal hyperexcitability seems to be an important cause of cognitive decline in aging and Alzheimer's disease (AD). Out of many antiepileptics, only levetiracetam improved cognitive dysfunction in AD patients and AD animal models by reducing hyperexcitability. As impaired inhibitory interneuronal function, rather than overactive neurons, seems to be the underlying cause, improving impaired neuronal function rather than quieting overactive neurons might be relevant in explaining the lack of activity of the other antiepileptics. Interestingly, improvement of cognitive deficits by levetiracetam caused by small levels of soluble Aβ was accompanied by improvement of synaptic function and plasticity. As the negative effects of Aβ on synaptic plasticity strongly correlate with mitochondrial dysfunction, wehypothesized that the effect of levetiracetam on synaptic activity might be raised by an improved mitochondrial function. Accordingly, we investigated possible effects of levetiracetam on neuronal deficits associated with mitochondrial dysfunction linked to aging and AD. Levetiracetam improved several aspects of mitochondrial dysfunction including alterations of fission and fusion balance in a cell model for aging and early late-onset AD. We demonstrate for the first time, using immunohistochemistry and proteomics, that the synaptic vesicle protein 2A (SV2a), the molecular target of levetiracetam, is expressed in mitochondria. In addition, levetiracetam shows significant effect on the opening of the mitochondrial permeability transition pore. Importantly, the effects of levetiracetam were significantly abolished when SV2a was knockdown using siRNA. In conclusion, interfering with the SV2a protein at the mitochondrial level and thereby improving mitochondrial function might represent an additional therapeutic effect of levetiracetam to improve symptoms of late-onset AD.

A cell model for the initial phase of sporadic Alzheimer's disease

Recent data suggest that the combined effect of oxidative stress due to aging and slightly elevated amyloid-β (Aβ) levels initiate Alzheimer's disease (AD) long before the clinical onset. Investigations of this early phase are hampered by the lack of cellular or animal models reflecting this scenario. We used SH-SY5Y cells stably transfected with an additional copy of the human AβPP gene and artificial aging by complex I inhibition. These cells show slightly elevated Aβ levels, moderately decreased ATP levels, impaired mitochondrial membrane potential, and decreased mitochondrial respiration. Assessing mitochondrial dynamics with three different methods reveals a distinct shift toward mitochondrial fission and fragmentation in SH-SY5Y AβPPwt cells. We also performed electron cryo-tomography of isolated mitochondria to reveal that there were no major differences between SH-SY5Y control and SH-SY5Y AβPPwt mitochondria with respect to swelling or loss of cristae. Dystrophic neurites are an early pathological feature of AD. Interestingly, SH-SY5Y AβPPwt cells exhibit significantly longer neurites, likely due to substantially elevated levels of sAβPPα. Complex I inhibition also shows substantial effects on mitochondrial dynamics, impairs neuritogenesis, and elevates Aβ levels in both cell types. In SH-SY5Y AβPPwt cells, these defects were more pronounced due to a relatively elevated Aβ and a reduced sAβPPα production. Our findings suggest that the progression from low Aβ levels to the beginning of AD takes place in the presence of oxidative stress during normal aging. This mechanism not only results from additive effects of both mechanisms on mitochondrial function but might also be additionally aggravated by altered amyloidogenic processing.

The induction of anterior chamber inflammation by factors released from hydrogen peroxide-injured corneas: effect of dexamethasone and indomethacin

Studies from our laboratory have demonstrated the release of high levels of neutrophil chemotactic factors (NCF) from isolated rabbit corneas injured by hydrogen peroxide (H2O2). The purpose of the present study was to determine the biological activity of these factors and to test the hypothesis that the intracameral injection of these factors can induce inflammation of the anterior segment. Under sterile conditions, the epithelial surfaces of isolated rabbit corneas were incubated with a 300 ul mixture of glucose (G) (1mg/ml) and glucose oxidase (GO) (20 U/ml) at 37 degrees C for 6 hours. This supernatant solution was collected and a 100 ul sample containing NCF, but not H2O2, was injected into the anterior chamber of anesthetized rabbit eyes (n = 8). Anterior chamber inflammation, characterized by moderate corneal edema associated with a fibrinous anterior chamber reaction, was evident 2 and 4 hours after injection. Aqueous humor analysis revealed the presence of fibrin and a large number of neutrophils (32 +/- 5 x 10(4) cells/ml). Control eyes, on the other hand, showed normal morphology and low levels of neutrophils after the injection of 100 ul minimum essential medium (MEM) (n = 8) (1.2 +/- 0.14 x 10(4) cells/ml), G/GO mixture (n = 8) (5 +/- 0.86 x 10(4) cells/ml), or supernatant solutions collected from MEM-treated corneas (n = 8) (15 +/- 2 x 10(4) cells/ml). To determine whether the inflammatory reaction observed was due to a direct effect of the chemoattractants or mediated through stimulation of arachidonic acid (AA) metabolites, we pretreated rabbit eyes with a sterile solution of 0.1% dexamethasone (n = 8 eyes) or with a sterile solution of 3.4% indomethacin (n = 8 eyes) three times a day, for one day, prior to the injection of NCF supernatant solution. Examination 2 hours and 4 hours after injection revealed inflammation characterized by mild-to-moderate corneal edema associated with a fibrinous anterior chamber reaction was observed with or without prior treatment with AA metabolite inhibitors. No difference in the degree of inflammation was detected clinically. Results of these studies suggest that NCF released from H2O2-injured corneas can directly induce inflammation of the anterior segment, and that metabolites of AA are not mediating the observed in vivo response.

Cyclocreatine inhibits neutrophil accumulation in the myocardium of a canine model of coronary artery occlusion and reperfusion

This study tests the hypothesis that the administration of cyclocreatine before ischemia inhibits the release of neutrophil chemotactic factors from myocardial tissues and subsequently reduces neutrophil accumulation into ischemic areas. Adult mongrel dogs underwent left anterior descending coronary artery occlusion for 1 h, followed by a 2-h reperfusion. Cyclocreatine-treated dogs (n = 6) were injected intravenously with cyclocreatine solution (600 mg/kg) 1 h before the experiment and during ligation of the coronary artery. Control dogs (n = 6) were injected with saline. Neutrophil chemotactic activity was measured in plasma samples using standard modified Boyden chambers. In controls dogs, significantly elevated levels of chemotactic activity were recovered in blood samples taken during reperfusion (i.e., 2.8-3.5-fold; P < .0001) as compared to base-line activity recovered before occlusion. Preliminary biochemical characterizations revealed that the recovered chemotactic factors (via checkerboard analysis) are proteins of high molecular weight (greater than 100 kDa). Biopsy samples of control hearts showed an accumulation of a large number of neutrophils in the ischemic portions. Cyclocreatine-treated dogs, on the contrary, showed low levels of chemotactic activity during reperfusion, which correlated with the absence of neutrophils in ischemic areas. These results indicate the capability of cyclocreatine to inhibit the release of neutrophil chemotactic factors from ischemic myocardium, which subsequently prevented neutrophil accumulation.