Exploring the metabolic and antioxidant potential of solergy: Implications for enhanced animal production

Cell models are indispensable tools in biotechnology when investigating the functional properties of organic compounds. The emergence of various additives designed to enhance animal production has introduced the need for in-depth evaluations, which are often hindered by the complexities of in vivo testing. In this study, we harnessed cell-based models to scrutinize the impact of Solergy as a regulator of cellular metabolism with a particular focus on its modulation of glycogen and antioxidant effects. Our experiment was designed to include assessments of the influence of Solergy on the viability of both terrestrial and aquatic vertebrate cell models, which revealed the benign nature of Solergy and its lack of adverse effects. Furthermore, we examined the capacity of Solergy to modulate intracellular ATP concentrations and enhance glycogen accumulation. Notably, the antioxidant potential of Solergy and its ability to mitigate cellular aging were evaluated within the same cellular frameworks. The outcomes of our investigation suggest that Solergy is a potent metabolic regulator that elevates cellular activity while exerting an antioxidant effect. Importantly, our study demonstrates that Solergy does not induce changes in membrane oxidation. These findings indicate the potential of using Solergy to regulate glycogen synthesis, intracellular ATP concentrations, and oxidative stress in production animals. The multifaceted effects of this additive, which acts as both a metabolism enhancer and an antioxidant, open doors to the creation of custom diets tailored to meet specific production needs while maintaining stable production parameters.

A synergy of the nutritional additives taurine and silymarin in salmon farming: evaluation with the CHSE-214 cellular model

The use of additives in the feed industry for producing fish has become the focus of constant change and research. The formulation of a product as a feeding strategy leads to the use of more than one molecule with particular characteristics to seek a synergistic effect when they are administered in the food. The application of taurine and silymarin in the salmon farming industry needs the exploration of the synergistic effects. For this study, we evaluated the effects of various concentrations of additives in the cell line CHSE-214 of Oncorhynchus tshawytscha. The cells were exposed to increasing concentrations of hydrogen peroxide as an oxidizing agent and were then given treatments of taurine, silymarin or both additives together. Our results indicate that the molecules had separate antioxidant effects, and the taurine treatment reached the highest number of cells per area at a dose of 100 ppm. However, if the cells were treated together at 100 ppm, silymarin achieved outstanding effects. However, when the treatment with both molecules was increased to 500 ppm of taurine, the effect was blocked, and the treatment acted as an antagonist. Our data indicate that the formulation of diets must be rigorously carried out, especially for determining the doses to be used to generate synergy among antioxidant additives and to reduce the effect of antagonism between the additives. Likewise, the use of cell lines is a strategy to evaluate the mechanisms of action for additives that are used in the development of diets for the salmon industry.

Polyphenols obtained from Didymosphenia geminata (Lyngbye) Schmith altered the viability and proliferation of salmonids cells lines SHK-1 and CHSE-214

Didymosphenia geminata (Lyngbye) Schmidt, also referred to as Didymo, is an invasive diatom that forms nuisance mats. Since it was first reported in our country in approximately 2010, Didymo has expanded and colonized different rivers in the Zona Austral region of Chile. Its biology and effects on ecosystems are still being studied because Didymo is an invasive algal mat that forms in a range of systems from oligotrophic austral rivers to more subtropical systems. We aimed to evaluate the viability of two salmonid cell lines, CHSE-214 and SHK-1 (somatic and embryonic cell lines, respectively), in dilutions of river water alone and in river water contaminated with Didymo or polyphenols extracted from Didymo under controlled conditions. We developed an artificial river system (2 aquariums/replicate) from five different rivers from the central area (Bio-Bio) and Patagonia area (Futaleufú) of Chile to maintain Didymo in the benthic phase. The Didymo populations were maintained for six months in the water from the rivers, after which samples were obtained. Following the extraction of polyphenols from the Didymo samples maintained in the artificial rivers, toxicity assays (10 assays) were performed to determine cell viability. Our results indicated that the CHSE-214 cells were highly sensitive to increasing concentrations of Didymo extracts. We observed a 50% reduction in cell viability after 24 h of exposure to a 0.01 V/V dilution, and this treatment further reduced the proliferative capacity by 70% after 120 h. The SHK-1 cells were less responsive, showing only a 20% decrease in viability at 24 h and a lower cell proliferation rate (45%) after 120 h, which remained higher than that of the CHSE-214 cells. We conclude that certain cell types are sensitive to Didymo in rivers, suggesting that there are chronic effects on several aquatic species following exposure to these diatom substances. These effects should be further studied using this laboratory model to understand the full impact of Didymo on river ecosystems.

Mat thickness associated with Didymosphenia geminata and Cymbella spp. in the southern rivers of Chile

Didymosphenia geminata is a diatom that can alter aquatic systems. Several investigations have shown as chemical, and hydraulic factors have a great influence on the proliferation of D. geminata, but the study of other microalgae that could be associated with it has been poorly addressed. The objective of this study is to evaluate the relationship between mat thickness, D. geminata and another taxon that produces mucilage, Cymbella, while also considering physical and chemical factors. For this, two samples were taken, one in the spring of 2013 and the other in the autumn of 2014, from eight rivers in central-southern Chile-South America, where the benthic community was characterized, and the thickness of the mat was measured. The results show that the mat thickness on sites with the presence of both taxa is doubled, and while sites with D. geminata presence showed mat peak on autumn, sites with Cymbella spp. presence showed on spring. Also, higher values of mat thickness associated with low cell densities of D. geminata and intermediate cell densities of Cymbella spp. Finally, physicochemical variables that better explain mat thickness are phosphorus and water temperature. An alternation process of mucilage production may explain these results by these taxa strongly related to physicochemical variables. The present study contributes evidence about the relationship between mat thickness D. geminata and other microalgae contribution, and aquatic condition for this development.

Generación de un protocolo para la síntesis de nanopartículas de quitosano cargadas con florfenicol a través del método de gelación iónica

La formación de nanopartículas de quitosano mediante el método de gelación iónica tiene un alto potencial para la carga, transporte y liberación controlada de moléculas. Es un método sencillo y las nanopartículas presentan buena absorción, estabilidad, biocompatibilidad y baja toxicidad. El florfenicol es uno de los antibióticos más utilizados en la industria acuícola y es administrado mezclado con el alimento en altas concentraciones, lo cual genera problemas de dosis efectivas y de residuos no deseados. De esta manera, la síntesis de nanopartículas de quitosano (Q) cargadas con florfenicol podría otorgar ventajas a la hora de proteger, transportar y liberar de forma controlada el fármaco en peces de interés económico. En el presente estudio se sintetizaron nanopartículas de quitosano y tripolifosfato de sodio (TPP) con y sin florfenicol para evaluar su carga efectiva y liberación. Los resultados obtenidos con espectrometría FTIR corroboran la formación de las nanopartículas de Q-TPP con los cambios observados en los patrones de espectros infrarojo entre el quitosano matriz y las nanopartículas sintetizadas. Las nanopartículas de Q-TPP pueden cargar entre 48 y 50% de florfenicol en su interior. El ensayo de liberación in vitro del antibiótico mostró una liberación controlada y estable en el tiempo en condiciones de pH ácido y temperatura controlada de 15° C de hasta 10 días. Finalmente, se muestra que las nanopartículas de Q-TPP tienen potencial para atrapar y liberar de forma controlada el fármaco evaluado.

Effects of storage time on the motility, mortality and calcium levels of Atlantic salmon Salmo salar spermatozoa

This study estimates spermatozoa mortality, morphology, motility and intracellular calcium levels in Atlantic salmon Salmo salar milt after prolonged storage. Milt samples were preserved at 4° C for 25 days and then evaluated for mortality. Motility remained high for the first 3 days and the mortality was low during the first 5 days of storage. A decrease of >50% in calcium content was observed after 5 days of storage. When spermatozoa were activated, calcium levels increased >200% in relative fluorescence units (RFU); this rate of increase was lost when the samples were stored for extended periods of time and was only partially manifested in a zero calcium solution. The results suggest that in vitro storage of S. salar spermatozoa at 4° C for a period of 3 days preserves motility and limits mortality to levels similar to those of fresh spermatozoa. This method also maintains intracellular calcium storage critical for spermatozoa performance.

Antimutagenic evaluation of traditional medicinal plants from South America Peumus boldus and Cryptocarya alba using Drosophila melanogaster

Peumus boldus Mol. ("Boldo") and Cryptocarya alba Mol. Looser ("Peumo") are medicinal shrubs with wide geographical distribution in South America. Their leaves and fruits are commonly used in traditional medicine because they exhibit natural medicinal properties for treatment of liver disorders and rheumatism. However, there are no apparent data regarding potential protective effects on cellular genetic components. In order to examine potential mutagenic and/or antimutagenic effects of these medicinal plants, the Drosophila melanogaster (D. melanogaster) wing-spot test was employed. This assay detects a wide range of mutational events, including point mutations, deletions, certain types of chromosomal aberrations (nondisjunction), and mitotic recombination. Qualitative and quantitative analyses of phenolic and anthocyanin compounds were carried out using biochemical and high-performance liquid chromatography methodologies. In addition, the antioxidant capacity of P. boldus and C. alba leaf extracts was also analyzed. P. boldus and C. alba extracts did not induce significant mutagenic effects in the D. melanogaster model. However, simultaneous treatment of extracts concurrently with the mutagen ethyl methane sulphonate showed a decrease of mutant spots in somatic cells of D. melanogaster, indicating desmutagenic effects in this in vivo model. Flavonoids and anthocyanins were detected predominantly in the extracts, and these compounds exerted significant antioxidant capacity. The observed antimutagenic effects may be related to the presence of phytochemicals with high antioxidant capacity, such as flavonoids and antohocyanins, in the extracts.

Amyloid pore-channel hypothesis: effect of ethanol on aggregation state using frog oocytes for an Alzheimer's disease study

Alzheimer's disease severely compromises cognitive function. One of the mechanisms to explain the pathology of Alzheimer’s disease has been the hypotheses of amyloid-pore/channel formation by complex Aβ-aggregates. Clinical studies suggested the moderate alcohol consumption can reduces probability developing neurodegenerative pathologies. A recent report explored the ability of ethanol to disrupt the generation of complex Aβ in vitro and reduce the toxicity in two cell lines. Molecular dynamics simulations were applied to understand how ethanol blocks the aggregation of amyloid. On the other hand, the in silico modeling showed ethanol effect over the dynamics assembling for complex Aβ-aggregates mediated by break the hydrosaline bridges between Asp 23 and Lys 28, was are key element for amyloid dimerization. The amyloid pore/channel hypothesis has been explored only in neuronal models, however recently experiments suggested the frog oocytes such an excellent model to explore the mechanism of the amyloid pore/channel hypothesis. So, the used of frog oocytes to explored the mechanism of amyloid aggregates is new, mainly for amyloid/pore hypothesis. Therefore, this experimental model is a powerful tool to explore the mechanism implicates in the Alzheimer’s disease pathology and also suggests a model to prevent the Alzheimer’s disease pathology. [BMB Reports 2015; 48(1): 13-18]

Wnt5a inhibits K(+) currents in hippocampal synapses through nitric oxide production

Hippocampal synapses play a key role in memory and learning processes by inducing long-term potentiation and depression. Wnt signaling is essential in the development and maintenance of synapses via several mechanisms. We have previously found that Wnt5a induces the production of nitric oxide (NO), which modulates NMDA receptor expression in the postsynaptic regions of hippocampal neurons. Here, we report that Wnt5a selectively inhibits a voltage-gated K(+) current (Kv current) and increases synaptic activity in hippocampal slices. Further supporting a specific role for Wnt5a, the soluble Frizzled receptor protein (sFRP-2; a functional Wnt antagonist) fully inhibits the effects of Wnt5a. We additionally show that these responses to Wnt5a are mediated by activation of a ROR2 receptor and increased NO production because they are suppressed by the shRNA-mediated knockdown of ROR2 and by 7-nitroindazole, a specific inhibitor of neuronal NOS. Together, our results show that Wnt5a increases NO production by acting on ROR2 receptors, which in turn inhibit Kv currents. These results reveal a novel mechanism by which Wnt5a may regulate the excitability of hippocampal neurons.

Water contaminated with Didymosphenia geminata generates changes in Salmo salar spermatozoa activation times

Didimosphenia geminata ("didymo"), has become a powerful and devastating river plague in Chile. A system was developed in D. geminata channels with the purpose evaluating the effects of water polluted with didymo on the activation of Atlantic salmon (Salmo salar) spermatozoa. Results indicate that semen, when activated with uncontaminated river water had an average time of 60±21s. When using Powermilt, (a commercial activator), times of 240±21s are achieved, while rivers contaminated with D. geminata achieve a motility time of 30±12s. Interestingly enough, the kinetic parameters of VSL, VCL and VAP showed no significant changes under all of the conditions. Furthermore, the presence of D. geminata reduces activation time of the samples as the cells age, indicating increased effects in spermatozoa that are conserved for more than 5 days. D. geminata has antioxidant content, represented by polyphenols; 200ppm of polyphenol were obtained in this study per 10g of microalgae. Spermatozoa exposed to these extracts showed a reduction in mobility time in a dose dependent manner, showing an IC50 of 15ppm. The results suggest an effect on spermatozoa activation, possibly due to the release of polyphenols present in contaminated rivers, facilitating the alteration of sperm motility times, without affecting the viability or kinetics of the cells. These findings have important implications for current policy regarding the control of the algae. Current control measures focus on the number of visible species, and not on the compounds that they release, which this study shows, also have a problematic effect on salmon production.

Effects of tetrahydrohyperforin in mouse hippocampal slices: neuroprotection, long-term potentiation and TRPC channels

Tetrahydrohyperforin (IDN5706) is a semi-synthetic compound derived from hyperforin (IDN5522) and is the main active principle of St. John's Wort. IDN5706 has shown numerous beneficial effects when administered to wild-type and double transgenic (APPswe/PSEN1ΔE9) mice that model Alzheimer's disease. However, its mechanism of action is currently unknown. Toward this end, we analysed field excitatory postsynaptic potentials (fEPSPs) in mouse hippocampal slices incubated with IDN5706 and in the presence of the TRPC3/6/7 activator 1-oleoyl-2-acetyl-sn-glycerol (OAG), the TRPC channel blocker SKF96365, and neurotoxic amyloid β-protein (Aβ) oligomers. To study spatial memory, Morris water maze (MWM) behavioural tests were conducted on wild-type mice treated with IDN5706 and SKF96365. In silico studies were conducted to predict a potential pharmacophore. IDN5706 and OAG had a similar stimulating effect on fEPSPs, which was inhibited by SKF96365. IDN5706 protected from reduced fEPSPs induced by Aβ oligomers. IDN5706 improved spatial memory in wild-type mice, an effect that was counteracted by co-administration of SKF96365. Our in silico studies suggest strong pharmacophore similarity of IDN5706 and other reported TRPC6 activators (IDN5522, OAG and Hyp9). We propose that the effect of IDN5706 is mediated through activation of the TRPC3/6/7 channel subfamily. The unveiling of the drug's mechanism of action is a necessary step toward the clinical use of IDN5706 in Alzheimer's disease.

Functional and structural effects of amyloid-β aggregate on Xenopus laevis oocytes

Xenopus laevis oocytes exposed to amyloid-β aggregate generated oscillatory electric activity (blips) that was recorded by two-microelectrode voltage-clamp. The cells exhibited a series of "spontaneous" blips ranging in amplitude from 3.8 ± 0.9 nA at the beginning of the recordings to 6.8 ± 1.7 nA after 15 min of exposure to 1 μM aggregate. These blips were similar in amplitude to those induced by the channel-forming antimicrobial agents amphotericin B (7.8 ± 1.2 nA) and gramicidin (6.3 ± 1.1 nA). The amyloid aggregate-induced currents were abolished when extracellular Ca(2+) was removed from the bathing solution, suggesting a central role for this cation in generating the spontaneous electric activity. The amyloid aggregate also affected the Ca(2+)-dependent Cl(-) currents of oocytes, as shown by increased amplitude of the transient-outward chloride current (T(out)) and the serum-activated, oscillatory Cl(-) currents. Electron microcopy revealed that amyloid aggregate induced the dissociation of the follicular cells that surround the oocyte, thus leading to a failure in the electro-chemical communication between these cells. This was also evidenced by the suppression of the oscillatory Ca(2+)-dependent ATP-currents, which require proper coupling between oocytes and the follicular cell layer. These observations, made using the X. laevis oocytes as a versatile experimental model, may help to understand the effects of amyloid aggregate on cellular communication.

Wnt-5a is a synaptogenic factor with neuroprotective properties against Aβ toxicity

BACKGROUND

We have recently found that Wnt-5a regulates the synaptic structure and function in hippocampal neurons. This ligand is expressed in the hippocampus, stimulates dendritic spine morphogenesis and increases glutamatergic neurotransmission. Moreover, we have also shown that Wnt-5a induces the clustering of PSD-95.

OBJECTIVE

To explore the role of Wnt-5a in the formation of synaptic contacts.

METHODS

Primary rat hippocampal neurons were exposed to a formylated hexapeptide (Foxy-5) derived from the sequence of Wnt-5a to study synapse formation and function.

RESULTS

In short-term experiments, Wnt-5a only induced the clustering of PSD-95 but had no effect on the density of presynaptic puncta, while in long-term experiments, it induced both pre- and postsynaptic protein clustering and the number of synaptic contacts, in agreement with electrophysiological studies. In long-term experiments, Foxy-5 increased miniature excitatory postsynaptic current amplitude and frequency.

CONCLUSION

Our findings indicate that Wnt-5a induces synapse formation in hippocampal neurons. In addition, we discuss recent findings indicating a neuroprotective action of Wnt-5a against Aβ neurotoxicity.

Effect of aracnotoxin from Latrodectus mactans on bovine sperm function: modulatory action of bovine oviduct cells and their secretions

Latrodectus mactans' aracnotoxin (Atx) induces changes in sperm function that could be used as a co-adjuvant in male contraceptive barrier methods. This effect includes the suppression of intracellular reactive oxygen species (ROS), an event necessary for capacitation, chemotaxis and acrosome reaction (AR). The sperm that are not trapped by the barrier method can reach the oviduct before fertilisation and be exposed to the secretions of the oviducts. This study evaluated the effect of bovine tubal explants (TU) and conditioned media (CM) from the ampullar and isthmal regions on spermatozoa exposed to Atx. Thawed bovine sperm were incubated with Atx, TU and CM from the ampullar and isthmal regions for 4 h and then DNA integrity, intracellular ROS and lysophosphatidylcholine-induced AR were determined. Spermatozoa exposed to Atx and co-incubated with TU and CM for 4 h produced an increase in sperm DNA damage, a decrease in ROS production and a decrease in %AR, compared with the control. A similar result was obtained from the co-incubation of spermatozoa with Atx. In conclusion, the effect of Atx is not modified by tubal cells or their secretions and this opens the door to future studies to evaluate the application of synthetic peptides obtained from Atx as a co-adjuvant of contraceptive barrier methods.

The GABA(A)ρ receptors in hippocampal spontaneous activity and their distribution in hippocampus, amygdala and visual cortex

A bicuculline-resistant and TPMPA-sensitive GABAergic component was identified in hippocampal neurons in culture and in acute isolated brain slices. In both preparations, total GABAergic activity showed two inactivation kinetics: fast and slow. RT-PCR, in situ hybridization (ISH) and immunohistochemistry detected expression of GABAρ subunits. Immunogold and electron microscopy indicated that the receptors are mostly extrasynaptic. In addition, by RT-PCR and immunofluorescence we found GABAρ present in amygdala and visual cortex.

Open or laparoscopic nephrectomy and extracoroporeal repair of complicated renal artery aneurysms: techniques for renal salvage

Renal artery aneurysm is an infrequently seen disease. The most feared symptom is rupture, which is often rapidly fatal. Indications for intervention include size, intractable symptoms and pregnancy. Many cases are managed by endovascular techniques; however, very complex cases often are referred to the urologist. We report our experience with the rarely used technique of renal artery aneurysms repair comprised of nephrectomy, extracorporeal vascular reconstruction with aneurysmectomy, and autotransplant.

Canonical Wnt3a modulates intracellular calcium and enhances excitatory neurotransmission in hippocampal neurons

A role for Wnt signal transduction in the development and maintenance of brain structures is widely acknowledged. Recent studies have suggested that Wnt signaling may be essential for synaptic plasticity and neurotransmission. However, the direct effect of a Wnt protein on synaptic transmission had not been demonstrated. Here we show that nanomolar concentrations of purified Wnt3a protein rapidly increase the frequency of miniature excitatory synaptic currents in embryonic rat hippocampal neurons through a mechanism involving a fast influx of calcium from the extracellular space, induction of post-translational modifications on the machinery involved in vesicle exocytosis in the presynaptic terminal leading to spontaneous Ca(2+) transients. Our results identify the Wnt3a protein and a member of its complex receptor at the membrane, the low density lipoprotein receptor-related protein 6 (LRP6) coreceptor, as key molecules in neurotransmission modulation and suggest cross-talk between canonical and Wnt/Ca(2+) signaling in central neurons.

Beta-amyloid causes depletion of synaptic vesicles leading to neurotransmission failure

Alzheimer disease is a progressive neurodegenerative brain disorder that leads to major debilitating cognitive deficits. It is believed that the alterations capable of causing brain circuitry dysfunctions have a slow onset and that the full blown disease may take several years to develop. Therefore, it is important to understand the early, asymptomatic, and possible reversible states of the disease with the aim of proposing preventive and disease-modifying therapeutic strategies. It is largely unknown how amyloid beta-peptide (A beta), a principal agent in Alzheimer disease, affects synapses in brain neurons. In this study, we found that similar to other pore-forming neurotoxins, A beta induced a rapid increase in intracellular calcium and miniature currents, indicating an enhancement in vesicular transmitter release. Significantly, blockade of these effects by low extracellular calcium and a peptide known to act as an inhibitor of the A beta-induced pore prevented the delayed failure, indicating that A beta blocks neurotransmission by causing vesicular depletion. This new mechanism for A beta synaptic toxicity should provide an alternative pathway to search for small molecules that can antagonize these effects of A beta.

Synaptic effects of low molecular weight components from Chilean Black Widow spider venom

alpha-Latrotoxin is the principal component of the venom from the euroasiatic Black Widow spider and has been studied for its pharmacological use as a synaptic modulator. Interestingly, smaller molecular weight fractions have been found to be associated with this toxin, but their cellular actions have not been studied in detail. The venom from the Chilean Black Widow spider (Latrodectus mactans) does not produce alpha-latrotoxin, however it does contain several small polypeptides. We have recently demonstrated cellular effects of these peptides at the synaptic level using whole-cell patch clamp techniques. Purified venom from the glands of L. mactans was studied in 12 DIV rat hippocampal neuronal cultures. Venom at a concentration of 10nM was able to decrease neuronal conductance thereby increasing membrane resistance. This effect on the passive properties of the neurons induced a change in action potential kinetics simulating the action of classic potassium channel blockers. These changes produced an increase in spontaneous synaptic activity in rat hippocampal cultures in the presence of the venom in a concentration- and time-dependent manner. These results indicate that venom from Chilean spider L. mactans is capable of increasing cell membrane resistance, prolonging the action potential and generating an increase in synaptic activity demonstrating an interesting pharmacological effect of these low molecular weight fragments.

S-Methylcysteine may be a Causal Factor in Monohalomethane Neurotoxicity

S-methylcysteine (SMC) is formed after exposure to monohalomethanes in rodents as well as in humans. The present study was performed to study whether SMC, directly or indirectly, contributes to the well-known neurotoxicity of monohalomethanes. We have investigated the effects of acute exposure to SMC by means of electrophysiolocal measurements in freshly prepared hippocampal slices and dissociated hippocampal neurons in culture. For longer-term exposures (24 h) we have used organotypic cultures (2 weeks in culture), taking electrophysiologic recordings and assessing membrane integrity with propidium iodide (PI) fluorescence. We found that only high concentrations of SMC (10(-2) M; exposure time 30 min) in freshly isolated slices of adult rats reduce synaptically evoked population spikes in the CA1 region. This effect was at least partially reversible. In organotypic cultures, at 5 x 10(-5) M after 24 h of exposure, SMC compromises membrane integrity as revealed by PI fluorescence, only in the dentate gyrus, spreading to pyramidal cell layers at 50 x 10(-4) M. At 5 x 10(-6) and 2 x 10(-5) M, under the same experimental conditions, no changes were seen with the PI method, but we recorded increased population spike amplitudes, repetitive discharges and frequency potentiation (at a stimulus repetition rate of 0.05 Hz). Using whole-cell patch clamp in hippocampal dissociated neurons we have found that SMC (applied for approximately 1s) reduces GABA-induced currents ( IC(50) = 4.4 x 10(-4) M) without having an effect of its own, acting like a competitive antagonist at GABA(A) receptors. Our findings are in line with the view that the ability of monohalomethanes to induce the formation of SMC is an important factor for their neurotoxicity, provided that SMC is allowed to act at least for several hours. The effects exerted by SMC seem to be due, at least in part, to its interaction with GABA receptors.

Modulation of glycine-activated ion channel function by G-protein betagamma subunits

Glycine receptors (GlyRs), together with GABA(A) and nicotinic acetylcholine (ACh) receptors, form part of the ligand-activated ion channel superfamily and regulate the excitability of the mammalian brain stem and spinal cord. Here we report that the ability of the neurotransmitter glycine to gate recombinant and native ionotropic GlyRs is modulated by the G protein betagamma dimer (Gbetagamma). We found that the amplitude of the glycine-activated Cl- current was enhanced after application of purified Gbetagamma or after activation of a G protein-coupled receptor. Overexpression of three distinct G protein alpha subunits (Galpha), as well as the Gbetagamma scavenger peptide ct-GRK2, significantly blunted the effect of G protein activation. Single-channel recordings from isolated membrane patches showed that Gbetagamma increased the GlyR open probability (nP(o)). Our results indicate that this interaction of Gbetagamma with GlyRs regulates both motor and sensory functions in the central nervous system.

Rapid stimulation of L-arginine transport by D-glucose involves p42/44(mapk) and nitric oxide in human umbilical vein endothelium

D-glucose infusion and gestational diabetes induce vasodilatation in humans and increase L-arginine transport and nitric oxide (NO) synthesis in human umbilical vein endothelial cells. High D-glucose (25 mmol/L, 2 minutes) induced membrane hyperpolarization and an increase of L-arginine transport (V(max) 6.1+/-0.7 versus 4.4+/-0.1 pmol/ microg protein per minute) with no change in transport affinity (K(m) 105+/-9 versus 111+/-16 micromol/L). L-[3H]citrulline formation and intracellular cGMP, but not intracellular Ca2+, were increased by high D-glucose. The effects of D-glucose were mimicked by levcromakalim (ATP-sensitive K+ channel blocker), paralleled by p42/p44(mapk) and Ser(1177)-endothelial NO synthase phosphorylation, inhibited by N(G)-nitro-L-arginine methyl ester (L-NAME; NO synthesis inhibitor), glibenclamide (ATP-sensitive K+ channel blocker), KT-5823 (protein kinase G inhibitor), PD-98059 (mitogen-activated protein kinase kinase 1/2 inhibitor), and wortmannin (phosphatidylinositol 3-kinase inhibitor), but they were unaffected by calphostin C (protein kinase C inhibitor). Elevated D-glucose did not alter superoxide dismutase activity. Our findings demonstrate that the human fetal endothelial L-arginine/NO signaling pathway is rapidly activated by elevated D-glucose via NO and p42/44(mapk). This could be determinant in pathologies in which rapid fluctuations of plasma D-glucose may occur and may underlie the reported vasodilatation in early stages of diabetes mellitus.

Inhibition of nitrobenzylthioinosine-sensitive adenosine transport by elevated D-glucose involves activation of P2Y2 purinoceptors in human umbilical vein endothelial cells

Chronic incubation with elevated D-glucose reduces adenosine transport in endothelial cells. In this study, exposure of human umbilical vein endothelial cells to 25 mmol/L D-glucose or 100 micromol/L ATP, ATP-gamma-S, or UTP, but not ADP or alpha,beta-methylene ATP, reduced adenosine transport with no change in transport affinity. Inhibition of transport by D-glucose, ATP, and ATP-gamma-S was associated with reduced maximal binding, with no changes in the apparent dissociation constant for nitrobenzylthioinosine (NBMPR). A significant reduction (approximately 60+/-10%, P<0.05; n=6) in the number of human equilibrative NBMPR-sensitive nucleoside transporters (hENT1s) per cell (1.8+/-0.1x10(6) in 5 mmol/L D-glucose) and in hENT1 mRNA levels was observed in cells exposed to D-glucose or ATP-gamma-S. Incubation with elevated D-glucose, but not with D-mannitol, increased the ATP release by 3+/-0.2-fold. The effects of D-glucose and nucleotides on the number and activity of hENT1 and hENT1 mRNA were blocked by reactive blue 2 (nonspecific P2Y purinoceptor antagonist), suramin (Galpha(s) protein inhibitor), or hexokinase but not by pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (nonselective P2 purinoceptor antagonist). Our findings demonstrate that inhibition of adenosine transport via hENT1 in endothelial cells cultured in 25 mmol/L D-glucose could be due to stimulation of P2Y2 purinoceptors by ATP, which is released from these cells in response to D-glucose. This could be a mechanism to explain in part the vasodilatation observed in the early stages of diabetes mellitus or in response to D-glucose infusion.

Modulation of adenosine transport by insulin in human umbilical artery smooth muscle cells from normal or gestational diabetic pregnancies

1. Adenosine transport was measured in human cultured umbilical artery smooth muscle cells, isolated from non-diabetic or gestational diabetic pregnancies, under basal conditions and after pretreatment in vitro with insulin. 2. Adenosine transport in non-diabetic smooth muscle cells was significantly increased by insulin (half-maximal stimulation at 0.33 +/- 0.02 nM, 8 h) and characterized by a higher maximal rate (V(max)) for nitrobenzylthioinosine (NBMPR)-sensitive (es) saturable nucleoside transport (17 +/- 5 vs. 52 +/- 12 pmol (microg protein)(-1) min(-1), control vs. insulin, respectively) and maximal binding sites (B(max)) for [(3)H]NBMPR (0.66 +/- 0.07 vs. 1.1 +/- 0.1 fmol (microg protein)(-1), control vs. insulin, respectively), with no significant changes in Michaelis-Menten (K(m)) and dissociation (K(d)) constants. 3. In contrast, in smooth muscle cells from diabetic pregnancies, where the values of V(max) for adenosine transport (59 +/- 4 pmol (microg protein)(-1) min(-1)) and B(max) for [(3)H]NBMPR binding (1.62 +/- 0.16 fmol (microg protein)(-1)) were significantly elevated by comparison with non-diabetic cells, insulin treatment (1 nM, 8 h) reduced the V(max) for adenosine transport and B(max) for [(3)H]NBMPR binding to levels detected in non-diabetic cells. 4. In non-diabetic cells, the stimulatory effect of insulin on adenosine transport was mimicked by dibutyryl cGMP (100 nM) and reduced by inhibitors of phosphatidylinositol 3-kinase (10 nM wortmannin), nitric oxide synthase (100 microM N (G)-nitro-L-arginine methyl ester, L-NAME) or protein synthesis (1 microM cycloheximide), whereas inhibition of adenylyl cyclase (100 microM SQ-22536) had no effect. 5. Wortmannin or SQ-22536, but not L-NAME or cycloheximide, attenuated the inhibitory action of insulin on the diabetes-induced stimulation of adenosine transport. 6. Protein levels of inducible NO synthase (iNOS) were similar in non-diabetic and diabetic cells, but were increased by insulin (1 nM, 8 h) only in non-diabetic smooth muscle cells. 7. Our results suggest that adenosine transport via the es nucleoside transporter is modulated differentially by insulin in either cell type. Insulin increased adenosine transport in non-diabetic cells via NO and cGMP, but inhibited the diabetes-elevated adenosine transport via activation of adenylyl cyclase, suggesting that the biological actions of adenosine may be altered under conditions of sustained hyperglycaemia in uncontrolled diabetes.

Efficacy of a proximal occlusion catheter with reversal of flow in the prevention of embolic events during carotid artery stenting: an experimental analysis

OBJECTIVE

The role of percutaneous angioplasty and stenting of carotid bifurcation lesions has been limited by its potential for producing embolic debris. We evaluated the efficacy of a proximal occlusion catheter (POC) in the prevention of embolic events during carotid artery stenting. In addition, pressure measurements relevant to the clinical application of this device were obtained from 10 patients undergoing carotid endarterectomy.

METHODS

The POC is a guiding catheter with an occlusion balloon attached on the outside of the catheter at its distal end. Occlusion of the common carotid artery (CCA) was achieved by inflating the balloon while access to carotid bifurcation lesions was obtained through the inner lumen. The POC was inserted in the CCA of 10 dogs via the femoral artery. The side port of the POC was connected to a sheath placed in the femoral vein, thereby creating an external arteriovenous shunt. Ten artificial radiopaque particles simulating embolic particles and contrast agent were introduced in the CCA and monitored fluoroscopically. As a control, the same procedure was performed with a standard guiding catheter without an occlusion balloon. In 10 patients undergoing carotid endarterectomy, the internal carotid artery (ICA) and external carotid artery stump pressures and the pressure in the internal jugular vein were measured.

RESULTS

Without the external arteriovenous shunt, in all animals there was prograde flow in the distal CCA despite CCA occlusion. This flow was derived from the thyroid artery. However, once the arteriovenous shunt was activated, reversal of flow in the distal CCA was achieved in each animal, and all the artificial particles were recovered from the side port of the POC. In the control group, each particle embolized to the brain (100%, P <.01). In the patients, the mean stump pressures in the ICA and external carotid artery and the jugular vein pressure were 51.8 +/- 14.2, 62.2 +/- 15.1, and 6.5 +/- 3.5 mm Hg, respectively. In each case, the jugular vein pressure was the lowest among the three.

CONCLUSIONS

Obtaining proximal CCA control by inflating the POC does not sufficiently prevent embolization. However, reversal of flow in the ICA can always be created with the external shunt, which effectively prevents embolization. Thus, POC may markedly lower procedural stroke rates during carotid artery stenting. The ability of POC to prevent embolization before crossing the lesion with a guidewire may be an important advantage over other distal protection devices.

Evaluation of endovascular abdominal aortic aneurysm repair: anatomical classification, procedural success, clinical assessment, and data collection

PURPOSE

To detail a methodology for evaluation of endovascular abdominal aortic aneurysm (AAA) repair that has been achieved through consensus of an international multidisciplinary team of investigators.

METHODS

This schema features an anatomical classification for AAAs, a definition of procedural success, and a procedure for clinical assessment, as well as the necessary data collection forms. Patient data include demographics, procedural and clinical success, complications, and follow-up. Procedural details can be related to anatomic situations, comorbid processes, devices, and effective aneurysmal exclusion.

RESULTS

These data would allow assessment of the procedures, physician learning curves, procedural indications, techniques, methodologies, the relationship of indications to success and complications, devices and subsequent graft patency, and aneurysmal exclusion.

CONCLUSIONS

The use of this standardized data collection system could enable physicians and industry to better understand endovascular AAA repair and ultimately improve patient care.

Magnetic resonance acquisition to determine the lumen length of a tortuous phantom aorta

PURPOSE

Endovascular abdominal aortic aneurysm repair is a technique that requires an accurate measurement of the aneurysm's lumen length prior to the procedure. This study examines the accuracy of luminal length measurement in an aortic phantom using magnetic resonance angiography (MRA) axial source images.

METHODS AND RESULTS

Tortuous phantom aortas were constructed using water-filled plastic tubing (7 mm in diameter with lengths of 80 to 160 mm). The tubes were molded into three-dimensional "S" or "C" shapes that simulated the luminal course of a tortuous aorta. Phantoms were imaged at angles of 0 degrees, 15 degrees, 30 degrees, and 45 degrees to the image slice direction on a 1.5T Signa MR scanner using a transaxial two-dimensional time-of-flight (TOF) and a T1-weighted spin-echo acquisition. The luminal length of the phantom was calculated after establishing the lumen center coordinates in axial source images and then measuring the distance between two sequential slices using the Pythagorean theorem. The accuracy of this measurement in the phantom was 89% to 99.6%, proportional to the length of the tubing. Accuracy was not affected by angulation of < 45 degrees.

CONCLUSION

Two-dimensional TOF MRA source images can provide an accurate measurement of the phantom aorta's lumen length.

Time-series analysis of myoelectric cycling of sphincter of Oddi: evidence of cycling during fed state

The sphincter of Oddi (SO) in the fasted opossum exhibits spontaneous cyclic spikeburst activity that is temporally related to the interdigestive migrating myoelectric complex (MMC) of the small intestine. After feeding, the cyclic activity is apparently disrupted. Our aim was to use time-series analysis to mathematically describe the periodic behavior of the fasted state and to determine whether this periodicity is present after feeding. Five opossums were chronically prepared with bipolar electrodes secured to the SO. With the animals fasted and conscious, myoelectric activity was recorded for at least two MMC cycles after which they were fed 170 kcal of cream. Spikeburst frequency data were analyzed by fast Fourier transform (FFT) and by digital band-pass filtering. Results from FFT analysis showed an intense low-frequency peak during the fasted state which persisted but was markedly depressed during the fed state. Analysis of the data after filtering also showed persistent sinusoidal activity at the MMC frequency after feeding, although the waveform was significantly depressed by both peak-to-peak amplitude and root mean square amplitude analysis. Recovery to normal fasting cyclic behavior with recovery of both FFT and filtered data was observed. We conclude that in the opossum the cyclic nature of the SO myoelectric activity observed during the fasted state persists after feeding, but is inhibited and masked by an increase in overall spikeburst activity.

Hypertonicity of intestinal smooth muscle as a factor of intestinal ischemia in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is thought to be secondary to mucosal ischemia. Because blood flow to the submucosal plexus is derived from vessels traversing three separate layers of visceral smooth muscle (longitudinal, circular, and muscularis mucosa), we investigated whether an increase in their tone might elicit mucosal ischemia. The intestinal intraluminal pressure (IIP) and the superior mesenteric artery (SMA) blood flow were evaluated in 23 dogs before and after either ligation of the SMA or neostigmine infusion into the SMA. Changes in vascularity were assessed by silicone rubber casting, India ink, or arteriography. Ten minutes after ligation of the SMA, there was a considerable increase in peristalsis, IIP, and inability to fill the intestinal microcirculation by the three methods described. Mucosal necrosis was present three hours later. In the neostigmine infusion group after a transient increase in mesenteric flow, the IIP rose 750%, while the mesenteric flow fell by 40%, mucosal necrosis occurred in one hour. When myotomy was performed on the antimesenteric border, mucosal necrosis was prevented. In a third group, neostigmine infused (femoral artery) in the hind limb demonstrated vasodilating effects. The data indicate that an increase in the myogenic tone and frequency of contraction of intestinal smooth muscle can produce mucosal ischemia, thus, intestinal hypertonicity may be an important factor in the pathogenesis of intestinal ischemia and possibly NEC. The effects of neostigmine in these experiments raise questions regarding its use during anesthesia in neonates with intestinal low flow states.