Mechanisms of the metabolic disturbances caused by hypoglycin and by pent-4-enoic acid in vivo studies

1. It was confirmed that administration of either hypoglycin or pent-4-enoate to rats caused severe hypoglycaemia and hypothermia. Hypothermia was prevented by keeping the animals in a thermoneutral environment (30°). Hypoglycaemia caused by hypoglycin lasted longer than that caused by pent-4-enoate. 2. Administration of hypoglycin to rats caused several volatile fatty acids to accumulate in the plasma. By contrast, the only volatile fatty acid found in plasma following administration of pent-4-enoate to rats was pent-4-enoate itself. 3. Several short-chain acyl-CoA dehydrogenase activities were irreversibly inactivated in extracts of mitochondria isolated from livers taken from rats after administration of hypoglycin; no inhibitions were found following administration of pent-4-enoate. 4. Evidence is presented that some of the branched-chain acyl-CoA esters are not, as often assumed, substrates for the butyryl-CoA dehydrogenase of β-oxidation, and that there are some specific branched-chain acyl-CoA dehydrogenases. 5. Mitochondria isolated from livers of hypoglycin-treated rats had their ability to oxidize acyl-carnitines severely impaired, and the O₂ consumption was consistent with the incomplete oxidation of the substrate as far as butyrate. Pyruvate oxidation was uninhibited in these mitochondria. 6. Mitochondria isolated from livers of pent-4-enoate-treated rats had their ability to oxidize acyl-carnitines impaired but the O₂ consumption was consistent with the complete oxidation of the substrate to acetoacetate. Pyruvate oxidation was also inhibited. During recovery, pyruvate oxidation was restored before that of palmitoyl-carnitine indicating that sequestration of mitochondrial CoASH is not the mechanism by which pent-4-enoate inhibits β-oxidation. 7. A working model is proposed to explain the in vivo effects of these compounds.     

Pathogenic role of the IgA molecule in IgA nephropathy

SUMMARY: Deposits of IgA together with complement in different body tissues support the hypothesis that IgA can trigger inflammatory mechanisms. IgA nephropathy (IgAN) is characterized by predominant mesangial IgA₁ deposits of a polymeric nature. So far, the mechanism of polymeric IgA₁ deposition in the kidney mesangium is poorly understood in IgAN. the exact pathophysiological sequel preceding renal fibrosis following the mesangial deposition of IgA immune complexes remains speculative. Recent in vitro studies revealed that binding of IgA to mesangial cells led to increased expression of growth factors, cytokines, and integrins. the release of these proinflammatory factors is likely to enhance inflammatory injury. In addition, the local renin-angiotensin system present in renal tissues also contributes to renal fibrosis through the activation of transforming growth factor-β. the question of whether polymeric IgA isolated from patients with IgAN exerted any upregulatory effect on the synthesis of macrophage migration inhibitory factor (MIF) and components of the renin-angiotensin system in human mesangial cells was explored. the in vitro studies revealed that polymeric IgA from IgAN patients upregulated the gene expression of renin and MIF in human mesangial cells in a dose-dependent manner. These findings further support the notion that glomerular deposition of IgA is not only a pathological epiphenomenon of IgAN, but that polymeric IgA exerts a pathophysiologic effect on the mesangial cells leading to renal fibrosis.     

SERCA-inhibiting activity of C-19 terpenolides from Thapsia garganica and their possible biogenesis

An investigation of Thapsia garganica afforded a series of tetracyclic C-19 dilactones, whose production was dependent on the time and location of the collection. These unusual tetrahomosesquiterpenoids are presumably biosynthesized via a carbon dioxide-triggered electrophilic polyolefin cyclization. Despite the structural differences with thapsigargin, these compounds showed SERCA-inhibiting properties.     

A toolbox facilitating stable transfection of Eimeria species

Stable transfection of Eimeria species has been difficult to achieve because of the obligate requirement for in vivo amplification and selection of the parasites. Strategies to generate and stabilise populations of transfected Eimeria tenella are described here, together with the identification of optimal parameters for the transfection process. A series of plasmids expressing selectable markers, including a panel of fluorescent reporter genes and a mutant Toxoplasma gondii dihydrofolate reductase-thymidylate synthase (DHFR-TSm2m3) gene that confers resistance to pyrimethamine, were electroporated into sporozoites of the E. tenella Wisconsin strain and stabilised by selective passage through chickens. Very high transfection efficiencies of up to 25% sporozoites in transient transfection and up to 9% oocysts following a single round of in vivo selection were achieved. Crucial factors include the use of very freshly harvested parasites with the AMAXA nucleofection system (program U33 in a cytomix-buffered reaction) and linearised plasmid DNA. The use of a restriction enzyme mediated integration (REMI) protocol boosted overall efficiency and elevated insertion rate per genome. Successful development of methods to generate and isolate stable populations of transfected Eimeria parasites will now stimulate rapid expansion of reverse genetic studies in this important coccidian.     

A hotspot mutation in transcription factor IKZF3 drives B cell neoplasia via transcriptional dysregulation

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Effect of peripheral 2-DG on opioid and neuropeptide Y gene expression

It is well known that 2-Deoxy-d-glucose (2-DG) blocks intracellular utilization of glucose and increases food intake. The aim of the present study was to determine whether administration of 2-DG alters gene expression of the orexigenic peptides, neuropeptide Y (NPY) and endogenous opioids, in the arcuate nucleus of the hypothalamus (ARC). Male Sprague–Dawley rats were injected peripherally (i.p.) with 2-DG (200 or 400 mg/kg body weight) and were sacrificed at 2 or 6 h post injection. Half of the animals were given ad libitum access to food whereas the other half of the animals were food-deprived. 2-DG increased food intake fourfold compared to saline injected animals, but did not affect NPY mRNA levels after 2 h. Messenger RNA levels of ProDynorphin (proDYN), but not pro-opiomelanocortin (POMC) nor proEnkephalin (proENK) were significantly decreased 2 h after 2-DG injection. Administration of 400 mg/kg of 2-DG increased mRNA levels of NPY in the arcuate nucleus after six h, but only in those animals not receiving food.