APETx4, a novel sea anemone toxin and a modulator of the cancer-relevant potassium channel K_V10.1

The human ether-à-go-go channel (hEag1 or KV10.1) is a cancer-relevant voltage-gated potassium channel that is overexpressed in a majority of human tumors. Peptides that are able to selectively inhibit this channel can be lead compounds in the search for new anticancer drugs. Here, we report the activity-guided purification and electrophysiological characterization of a novel KV10.1 inhibitor from the sea anemone Anthopleura elegantissima. Purified sea anemone fractions were screened for inhibitory activity on KV10.1 by measuring whole-cell currents as expressed in Xenopus laevis oocytes using the two-microelectrode voltage clamp technique. Fractions that showed activity on Kv10.1 were further purified by RP-HPLC. The amino acid sequence of the peptide was determined by a combination of MALDI- LIFT-TOF/TOF MS/MS and CID-ESI-FT-ICR MS/MS and showed a high similarity with APETx1 and APETx3 and was therefore named APETx4. Subsequently, the peptide was electrophysiologically characterized on KV10.1. The selectivity of the toxin was investigated on an array of voltage-gated ion channels, including the cardiac human ether-à-go-go-related gene potassium channel (hERG or Kv11.1). The toxin inhibits KV10.1 with an IC50 value of 1.1 μM. In the presence of a similar toxin concentration, a shift of the activation curve towards more positive potentials was observed. Similar to the effect of the gating modifier toxin APETx1 on hERG, the inhibition of Kv10.1 by the isolated toxin is reduced at more positive voltages and the peptide seems to keep the channel in a closed state. Although the peptide also induces inhibitory effects on other KV and NaV channels, it exhibits no significant effect on hERG. Moreover, APETx4 induces a concentration-dependent cytotoxic and proapoptotic effect in various cancerous and noncancerous cell lines. This newly identified KV10.1 inhibitor can be used as a tool to further characterize the oncogenic channel KV10.1 or as a scaffold for the design and synthesis of more potent and safer anticancer drugs

Umbilical uptakes and transplacental concentration ratios of amino acids in severe fetal growth restriction

Background: This study examines the relationship between placental amino acid (AA) transport and fetal AA demand in an ovine fetal growth restriction (FGR) model in which placental underdevelopment induces fetal hypoxemia and hypoglycemia. Methods: Umbilical uptakes of AA, oxygen, glucose, and lactate were measured near term in eight experimental ewes (FGR group) and in eight controls (C group). Results: The FGR group demonstrated significantly reduced umbilical uptakes of oxygen, glucose, lactate, and 11 AAs per kg fetus. The combined uptake of glucose, lactate, and AAs, expressed as nutrient/oxygen quotients, was reduced almost to 1.00 (FGR: 1.05 vs. C: 1.32, P ≤ 0.02). In contrast to a decrease in umbilical glucose concentration, all but one of the AAs that were transported from placenta to fetus demonstrated normal or elevated fetal concentrations, and five of the essential AAs were transported against a significantly higher feto/maternal (F/M) concentration ratio. This ratio peaked at the lowest fetal oxygen levels. Conclusion: We conclude that, in the hypoxic FGR fetus, the reduction in AA uptake is not due to a disproportionally small placental AA transport capacity. It is the consequence of decreased fetal oxidative metabolism and growth rate, which together reduce fetal AA demand. © 2013 International Pediatric Research Foundation, Inc

Nitrification in a highly polluted European estuary (the Scheldt estuary) and consequences on changing the natural isotopic ratio of ¹⁵N in particulate organic matter (poster)

The Scheldt Estuary is a highly polluted macrotidal estuary draining one of the most densely populated areas in the world (425 inhab/km²). The present nitrogen load to the estuary is approximately of 50 kT N / year from which about 20% is under the form of ammonium. This ammonium is almost completely nitrified in the estuary, even in winter conditions, when low temperatures are known to limit the activity of nitrifying bacteria. This is probably linked to the fact that water residence times are very long (75 days on the average) so that even with reduced nitrification rate depletion of ammonium is still possible. The oxidation of ammonium to nitrate by nitrifying bacteria results in an enrichment of N-NH4+ in its heavy isotope 15N. Indeed, the heavy isotope 15N is discriminated against the light 14N isotope during the oxidation process. Measurements of the delta15N in particulate organic matter and copepods show that the heavy 15N isotope of ammonium is most probably incorporated in the entire microbial food web. This indicates that, at least for some periods of the year, the microbial food web of the estuary is based on micro-organisms (phyto- and bacterioplankton) finding their N requirements by assimilating NH4+ rather than any other inorganic or organic N source

Development of sandwich ELISA and lateral flow immunoassay to detect almond in processed food

Almond (Prunus dulcis) represents a potential allergenic hazard that should be included in Allergen Control Plans. In this study, sandwich ELISA and lateral flow immunoassay (LFIA), using amandin (Pru du 6) as the target protein, were developed to detect almond in processed food and validated according to international guides. ELISA could detect 2 ng/mL and LFIA 30 ng/mL of pure amandin. No cross-reactivity was found on a panel of 50 food commodities with the exception of Pecan nut, Brazil nut and chestnut for which the cross-reactivity was lower than 0.02%. Furthermore, ELISA and LFIA were able to detect 0.12 and 0.70 ppm of almond protein in foods spiked with almond extract whereas 0.20 and 2.0 ppm could be detected in baked cookies incurred with almond, respectively. Both techniques could be applied for food manufacturers and control agencies for monitoring the presence of almond traces in food and working surfaces. © 2021 The Author(s

Correction:Chronic hyperglycaemia increases the vulnerability of the hippocampus to oxidative damage induced during post-hypoglycaemic hyperglycaemia in a mouse model of chemically induced type 1 diabetes

Correction: Diabetologia (2023) 66:1340-1352 https://doi.org/10.1007/s00125-023-05907-6The Original Article was published on 04 April 2023Unfortunately, the funding statement included in this paper did not fully satisfy the reporting requirements of the funder. The original article has been updated to include the sentence: ‘This paper reflects the authors’ views and the JU is not responsible for any use that may be made of the information it contains’

Correction:Chronic hyperglycaemia increases the vulnerability of the hippocampus to oxidative damage induced during post-hypoglycaemic hyperglycaemia in a mouse model of chemically induced type 1 diabetes

Correction: Diabetologia (2023) 66:1340-1352 https://doi.org/10.1007/s00125-023-05907-6The Original Article was published on 04 April 2023Unfortunately, the funding statement included in this paper did not fully satisfy the reporting requirements of the funder. The original article has been updated to include the sentence: ‘This paper reflects the authors’ views and the JU is not responsible for any use that may be made of the information it contains’

Counterregulatory hormone and symptom responses to hypoglycaemia in people with type 1 diabetes, insulin-treated type 2 diabetes or without diabetes:the Hypo-RESOLVE hypoglycaemic clamp study

Aim: The sympathetic nervous and hormonal counterregulatory responses to hypoglycaemia differ between people with type 1 and type 2 diabetes and may change along the course of diabetes, but have not been directly compared. We aimed to compare counterregulatory hormone and symptom responses to hypoglycaemia between people with type 1 diabetes, insulin-treated type 2 diabetes and controls without diabetes, using a standardised hyperinsulinaemic-hypoglycaemic clamp. Materials: We included 47 people with type 1 diabetes, 15 with insulin-treated type 2 diabetes, and 32 controls without diabetes. Controls were matched according to age and sex to the people with type 1 diabetes or with type 2 diabetes. All participants underwent a hyperinsulinaemic–euglycaemic-(5.2 ± 0.4 mmol/L)-hypoglycaemic-(2.8 ± 0.13 mmol/L)-clamp. Results: The glucagon response was lower in people with type 1 diabetes (9.4 ± 0.8 pmol/L, 8.0 [7.0–10.0]) compared to type 2 diabetes (23.7 ± 3.7 pmol/L, 18.0 [12.0–28.0], p &lt; 0.001) and controls (30.6 ± 4.7, 25.5 [17.8–35.8] pmol/L, p &lt; 0.001). The adrenaline response was lower in type 1 diabetes (1.7 ± 0.2, 1.6 [1.3–5.2] nmol/L) compared to type 2 diabetes (3.4 ± 0.7, 2.6 [1.3–5.2] nmol/L, p = 0.001) and controls (2.7 ± 0.4, 2.8 [1.4–3.9] nmol/L, p = 0.012). Growth hormone was lower in people with type 2 diabetes than in type 1 diabetes, at baseline (3.4 ± 1.6 vs 7.7 ± 1.3 mU/L, p = 0.042) and during hypoglycaemia (24.7 ± 7.1 vs 62.4 ± 5.8 mU/L, p = 0.001). People with 1 diabetes had lower overall symptom responses than people with type 2 diabetes (45.3 ± 2.7 vs 58.7 ± 6.4, p = 0.018), driven by a lower neuroglycopenic score (27.4 ± 1.8 vs 36.7 ± 4.2, p = 0.012). Conclusion: Acute counterregulatory hormone and symptom responses to experimental hypoglycaemia are lower in people with type 1 diabetes than in those with long-standing insulin-treated type 2 diabetes and controls.</p

Chiral separation of substituted phenylalanine analogues using chiral palladium phosphine complexes with enantioselective liquid–liquid extraction

Chiral palladium phosphine complexes have been employed in the chiral separation of amino acids and phenylalanine analogues in particular. The use of (S)-xylyl-BINAP as a ligand for the palladium complex in enantioselective liquid–liquid extraction allowed the separation of the phenylalanine analogues with the highest operational selectivity reported to date. 31P NMR, FTIR, FIR, UV-Vis, CD and Raman spectroscopy methods have been applied to gain insight into the binding mechanism of the amino acid substrates with the chiral palladium phosphine complexes. A complexation in a bidentate fashion is proposed.