Design,synthesis, and biological evaluation of novel selective peptide inhibitors of 11β-hydroxysteroid dehydrogenase 1

The enzyme 11β-HSD1 plays a crucial role in the tissue-specific regulation of cortisol levels and it has been associated with various diseases. Inhibition of 11β-HSD1 is an attractive intervention strategy and the discovery of novel selective 11β-HSD1 inhibitors is of high relevance. In this study, we identified and evaluated a new series of selective peptide 11β-HSD1 inhibitors with potential for skin care applications. This novel scaffold was designed with the aid of molecular modeling and two previously reported inhibitors. SAR optimization yielded highly active peptides (IC₅₀ below 400?nM) that were inactive at 1?µM concentration against structurally related enzymes (11β-HSD2, 17β-HSD1 and 17β-HSD2). The best performing peptides inhibited the conversion of cortisone into cortisol in primary human keratinocytes and the most active compound, 5d, was further shown to reverse cortisone-induced collagen damage in human ex-vivo tissue.     

Modification of life-history parameters of Daphnia pulex Leydig and D. magna Straus by the presence of Chaoborus sp.

Contamination of the culture water by high densities of phantom midge larvae, Chaoborus sp. resulted in size diminution, retarded reproduction and decrease in the clutch size of D. pulex, and size diminution of D. magna. Furthermore, D. pulex suffered heavy mortality. The results are discussed in the context of the hypothesis that energy is expended in the formation of defensive cyclomorphic spines. Other hypotheses are also discussed.     

Mapping of genes affecting linolenic acid content in Brassica rapa ssp. oleifera

F₂ progeny segregating for linolenic acid content were used to identify genes and develop markers for linolenic acid in spring turnip rape (Brassica rapa ssp. oleifera). A candidate gene approach applying the rapeseed fad3 gene and bulked segregant analysis with RAPD markers was used. A total of 27 markers were distributed in three linkage groups which each exhibited a QTL for linolenic acid. Jointly the three QTLs accounted for 73.5% of the variation in linolenic acid level in this population. The fad3 gene was mapped near one QTL controlling 23.5% of the variation. Allele-specific markers were developed for fad3 and can be used for marker-assisted selection in future spring turnip rape breeding programmes.     

Role of cellular energetics in ischemia-reperfusion and ischemic preconditioning of myocardium

A short period of ischemia followed by reperfusion produces a state of affairs in which the cells' potential for surviving longer ischemia is enhanced. This is called ischemic preconditioning. The effects of preconditioning are also related to the reperfusion damage which ensues upon tissue oxygenation. The role of the cellular energy state in reperfusion damage remains an enigma, although ischemic preconditioning is known to trigger mechanisms which contribute to the prevention of unnecessary ATP waste. In some species up to 80% of ATP hydrolysis in ischemia can be attributed to mitochondrial F₁-F₀-ATPase (ATP synthase), and a role for its inhibitor protein (IF₁) in ATP preservation has been proposed. Although originally regarded as limited to large animals with a slow heart beat, inhibition by IF₁ is probably a universal phenomenon. Coincidentally with ATPase inhibition, the decline in cellular ATP slows down, but even so the difference in ATP concentration between preconditioned and non-conditioned hearts is still small at the final stages of a long ischemia, when the beneficial effect of preconditioning is observable, although the energy state during reperfusion remains low in hearts which do not recover.     

The reactivity of ruthenium mono(bipyridine) carbonyl complexes in an alcoholic solution of alkali metal carbonates

Chlorine containing ruthenium bipyridine carbonyl compounds react readily in dilute alkaline solutions under a CO atmosphere affording a poorly soluble and air sensitive product that is suggested to have a polymeric nature. Various analysis methods (MS and TPD) were used in the characterisation of the product. The replacement of the axial chloride ligands in trans(Cl), cis(CO)[Ru(bpy)(CO)₂Cl₂] and [Ru(bpy)(CO)₂Cl]₂ is proposed to be the initial step in the polymerisation. The replacement of chlorides in methanolic solution was confirmed by isolating and characterising the dimeric intermediate [Ru(bpy)(CO)₂(COOCH₃)]₂.     

Role of Heparan Sulfate in Cellular Infection of Integrin-Binding Coxsackievirus A9 and Human Parechovirus 1 Isolates

Heparan sulfate/heparin class of proteoglycans (HSPG) have been shown to function in cellular attachment and infection of numerous viruses including picornaviruses. Coxsackievirus A9 (CV-A9) and human parechovirus 1 (HPeV-1) are integrin-binding members in the family Picornaviridae. CV-A9 Griggs and HPeV-1 Harris (prototype) strains have been reported not to bind to heparin, but it was recently shown that some CV-A9 isolates interact with heparin in vitro via VP1 protein with a specific T132R/K mutation. We found that the infectivity of both CV-A9 Griggs and HPeV-1 Harris was reduced by sodium chlorate and heparinase suggestive of HSPG interactions. We analyzed the T132 site in fifty-four (54) CV-A9 clinical isolates and found that only one of them possessed T132/R mutation while the other nine (9) had T132K. We then treated CV-A9 Griggs and HPeV-1 Harris and eight CV-A9 and six HPeV-1 clinical isolates with heparin and protamine. Although infectivity of Griggs strain was slightly reduced (by 25%), heparin treatment did not affect the infectivity of the CV-A9 isolates that do not possess the T132R/K mutation, which is in line with the previous findings. Some of the HPeV-1 isolates were also affected by heparin treatment, which suggested that there may be a specific heparin binding site in HPeV-1. In contrast, protamine (a specific inhibitor of heparin) completely inhibited the infection of both prototypes and clinical CV-A9 and HPeV-1 isolates. We conclude that T132R/K mutation has a role in heparin binding of CV-A9, but we also show data, which suggest that there are other HSPG binding sites in CV-A9. In all, we suggest that HSPGs play a general role in both CV-A9 and HPeV-1 infections.     

Mechanisms of D-Aspartate Release Under Ischemic Conditions in Mouse Hippocampal Slices

The release of preloaded D-[³H]aspartate, an unmetabolizable analogue of L-glutamate, was studied in superfused hippocampal slices from 7-day-old and 3-month-old (adult) mice under various cell-damaging conditions, including hypoxia, hypoglycemia, ischemia, oxidative stress and the presence of free radicals and metabolic poisons. The release was generally markedly enhanced in most of the above conditions, the responses being greater in adults than in developing mice. The presence of dinitrophenol had the most pronounced effect at both ages, followed by NaCN- and free-radical-containing media and ischemia. Hypoxia did not affect release in the immature hippocampus. Under most conditions K⁺ stimulation (50 mM) was still able markedly to enhance D-aspartate release. This potentiation under cell-damaging conditions in both adult and developing hippocampus signifies that increased L-glutamate release contributes to excitotoxicity and subsequent cell death. The mechanisms of ischemia-induced release of D-aspartate were analyzed in the adult hippocampus using ion channel inhibitors and modified superfusion media. The induced release proved to be partly Ca²⁺-dependent and partly Ca²⁺-independent. The results obtained with Na⁺ omission and homo- and heteroexchange with D-aspartate and L-glutamate demonstrated that a part of the release in normoxia and ischemia is mediated by the reversal of Na⁺-dependent glutamate transporters. The Na⁺ channel blockers amiloride and riluzole reduced the ischemia-induced release, also indicating the involvement of Na⁺ channels. In addition to this, the enhanced release of D-aspartate may comprise a swelling-induced component through chloride channels.     

Identification of the acidic degradation products of hexenuronic acid and characterisation of hexenuronic acid-substituted xylooligosaccharides by NMR spectroscopy

A 4-O-methylglucuronoxylan was converted into a hexenuronoxylan at high temperature and alkalinity similar to the conditions used during kraft pulping. The hexenuronoxylan was hydrolysed with enzymes, and acidic xylooligosaccharides were separated from the hydrolysate by anion-exchange and size-exclusion chromatography. The primary structure of the two main hexenuronic acid-substituted xylooligosaccharides (a tetramer and a pentamer) was determined by two-dimensional ¹H and ¹³C NMR spectroscopy. The 4-deoxy-hexenutronic acid is not stable under the acid hydrolysis step of conventional carbohydrate analysis. Here, we have identified the acidic degradation products of 4-deoxy-hexenuronic acid by NMR spectroscopy. Two degradation pathways were observed, both resulting in a furan derivative.     

Interactions of γ-L-glutamyltaurine with excitatory aminoacidergic neurotransmission

The in vitro effects of -L-glutamyltaurine on different stages of excitatory aminoacidergic neurotransmission were tested with -D-glutamyltaurine as reference. -L-Glutamyltaurine enhanced the K⁺-stimulated release of [³H]glutamate from cerebral cortical slices (25% at 0.1 mM) and slightly inhibited the uptake by crude brain synaptosomal preparations (about 10% at 1 mM). -L-Glutamyltaurine was also a weak displacer of glutamate and its agonists from their binding sites in brain synaptic membrane preparations, being, however, less selective to quisqualate (QA) sites than -D-glutamyltaurine. The basal influx of Ca²⁺ into cultured cerebellar granular cells was not affected by 1 mM -L-glutamyltaurine, but the glutamate- and its agonist-activated influx was significantly inhibited in low-Mg²⁺ (0.1 mM) and Mg²⁺-free media. The glutamate-evoked increase in free intracellular Ca²⁺ and the kainate-activated formation of cGMP in cerebellar slices were both markedly inhibited by 0.1 mM -L-giutamyltaurine. We propose that -L-glutamyltaurine may act as endogenous modulator in excitatory aminoacidergic neurotransmission.     

Lamotrigine and Carbamazepine Affect Differently the Release of D-[3H]Aspartate from Mouse Cerebral Cortex Slices: Involvement of NO

The effects of lamotrigine and carbamazepine on the release of preloaded D-[³H]aspartate and the involvement of nitric oxide were studied with mouse cerebral cortical slices in a superfusion system. Lamotrigine inhibited the veratridine-evoked release, whereas the K⁺-stimulated release was attenuated more strongly by carbamazepine than by lamotrigine. These effects were accentuated by the N-methyl-D-aspartate receptor antagonist L-2-amino-5-phosphonovalerate and the nitric oxide synthase inhibitor L-nitroarginine, but diminished by the nitric oxide donor sodium nitroprusside. The results show that in addition to the blockade of voltage-sensitive Na⁺ (and Ca²⁺) channels, NO-mediated mechanisms are probably involved in the anticonvulsant actions of carbamazepine and, in particular, those of lamotrigine.