Brief antecedent anoxia preserves mitochondrial function after sustained undersupply: A subcellular correlate to ischemic preconditioning?

Background: There is increasing evidence that mitochondria – owning a high degree of autonomy within the cell – might represent the target organelles of the myocardial protection afforded by ischemic preconditioning. It was the aim of the study to investigate a possible subcellular correlate to ischemic preconditioning at the mitochondrial level. In addition, we tested whether this protection depends on mitochondrial ATP-dependent potassium channels (K _ATP) and an might involve an attenuation of mitochondrial ATP hydrolysis during sustained anoxia.Methods and Results: Sustained anoxia (A, 14 min) and reoxygenation (R) completely inhibited state 3 and state 4 respiration of isolated ventricular mitochondria from Wistar rats. An antecedent brief anoxic incubation (4 min) followed by reoxygenation (2 min) prevented this loss of mitochondrial function. The protection afforded by anoxic preconditioning could be mimicked by the K _ATP opener diazoxide (30 μmol/l) and was completely inhibited by the K _ATP blocker 5-hydroxydecanoic acid (300 μmol/l). Structural mitochondrial integrity, as estimated from externalization of the mitochondrial enzymes creatine kinase and glutamateoxalacetate transaminase, remained unchanged between the groups, as did mitochondrial ATP loss during anoxia.Conclusion: For the first time, we provide direct evidence for a subcellular preconditioning-like functional mitochondrial adaptation to sustained anoxia. This effect apparently depends on opening of K_ATP but is independent of ATP preservation.     

High-throughput fluorescence screening of antioxidative capacity in human serum.

Diphenylhexatriene-labeled phosphatidylcholine and propionic acid have been established as selective fluorescence markers for the continuous determination of oxidation processes in the lipid and aqueous phases of unfractionated human serum. Oxidation of the respective fluorophores leads to a decrease in fluorescence intensity from which the time-dependent degradation of the marker molecule can be determined. The lag times preceding the propagation of oxidation are representative for the antioxidative capacity of the system, which may be influenced by exogenous factors, e.g., the antioxidants from the diet. Supplementation of human serum by quercetin, rutin, vitamin E, vitamin C, or total apple phenolics in vitro led to a decrease in oxidizability depending on the oxidation marker and the hydrophobicity of the antioxidant. Quercetin and vitamin E showed a higher in vitro capacity of protecting lipoproteins against oxidation. In contrast, rutin and vitamin C were more efficient as inhibitors in the aqueous phase. The same effect on serum was found after dietary consumption of apples. This result is in line with the known observation that intake of plant polyphenols leads to an increase in serum levels of hydrophilic antioxidants.     

The pattern of histone H4 expression in the tomato shoot apex changes during development

Two histone H4 cDNA clones were isolated from a tomato (Lycopersicon esculentum Mill.) shoot-tip cDNA library using a heterologous probe from barley (Hordeum vulgare L.). Both cDNAs, which are 81% identical in the coding region, are polyadenylated and belong to a small gene family in the tomato genome. Histone H4 message is abundant in young tissues and rare in older tissues. In the shoot apical meristem, the distribution of H4-expressing cells changes during development. In a juvenile vegetative apex, H4 message is detectable in the central region and the peripheral parts of the meristem. In a mature vegetative apical meristem, H4-expressing cells are localized in the peripheral zone extending into the provascular strands and the rib meristem whereas the central zone is almost devoid of H4 mRNA. After floral transition, H4 mRNA is found throughout the floral meristem, indicating a second change in the pattern of H4 expression. The observed changes in H4 expression are indicative of changes in the distribution of mitotic activity in the shoot apical meristem during plant development. In addition, H4-expressing cells were found to occur frequently in clusters, which may indicate a partial synchronization of cell divisions in the shoot apex.     

Synthesis, crystal structure, magnetic properties and electrochemical behaviour of the mixed valence compound [Cu(CN)3Cu(C3H10N2)2]

The binuclear mixed valence copper(I/II) compound [Cu^I(CN)₃Cu^II(tn)₂] (1) (tn = propane-1,3-diamine) and its acetonitrile adduct [Cu^I(CN)₃Cu^II(tn)₂] · 2MeCN (2) have been synthesized. Complex 1 crystallizes triclinic, space group , a = 8.117(2) Å, b = 8.389(2) Å, c = 11.920(2) Å, α = 108.728(3)°, β = 100.024(3)°, γ = 104.888(4)°, Z = 2, and compound 2 monoclinic, space group P2₁/m, a = 8.752(2) Å, b = 13.243(3) Å, c = 9.549(2) Å, β = 114.678(4)°, Z = 2. In both crystal structures, the binuclear [Cu^I(CN)₃Cu^II(tn)₂] complex with slightly different bonding geometries is formed. One of the three nitrogen atoms of a Cu^I(CN)₃ moiety is coordinated to Cu(II) at the apex of a square-pyramid with two chelating ligands tn on its base. The shortest intramolecular Cu^II?Cu^II distance in 1 is 5.640(7) Å. The EPR behaviour of 1 has been investigated at room temperature and at 77 K. The magnetic properties were measured in the temperature range 1.8-300 K.     

Rapid disease development in scrapie-infected mice deficient for CD40 ligand

The inhibition of CD40-CD40L interaction-mediated signalling was suggested as a therapeutic strategy for the treatment of Alzheimer's disease. Conversely, CD40-deficient neurons were reported to be more vulnerable to stress associated with ageing as well as nerve growth factor-beta and serum withdrawal. We studied the scrapie infection of CD40L-deficient (CD40L(-/-)) mice to see whether ablation of the CD40L gene would be beneficial or detrimental in this model of a neurodegenerative amyloidosis. CD40L(-/-) mice died on average 40 days earlier than wild-type control mice and exhibited a more pronounced vacuolation of the neuropil and an increased microglia activation. The experimental model indicates that a deficiency for CD40L is highly detrimental in prion diseases and reinforces the neuroprotective function of intact CD40-CD40L interactions. The stimulation of neuroprotective pathways may represent a possibility to delay therapeutically the disease onset in prion infections of the central nervous system.     

The architecture of chicken chromosome territories changes during differentiation

Background  

Between cell divisions the chromatin fiber of each chromosome is restricted to a subvolume of the interphase cell nucleus called chromosome territory. The internal organization of these chromosome territories is still largely unknown.     

Potency estimation of vaccine batches remains unaffected by anesthesia for intracerebral injection

Potency testing of rabies and whole-cell pertussis vaccine batches is still performed by an intracerebral (i.c.) challenge test, in conformity with international regulatory requirements. For the i.c. injection, the use of anesthesia is strongly recommended to alleviate the severe pain induced by the procedure. Today, anesthesia is not consistently mentioned in regulatory requirements, in contrast to the times when the potency tests were developed. The introduction of anesthesia is hampered, due to the lack of data on a hypothetical impact of anesthesia on potency estimation. Here, we show the comparative analysis of the extensive batch release data set of a rabies vaccine for human use that was tested in two laboratories of which only one applied anesthesia. In essence, we find that the mean batch test results were similar to each other, demonstrating that anesthesia for i.c. injection does not interfere with potency estimation. Consequently, we recommend the update of regulatory requirements and protocols and support the implementation of anesthesia for i.c. injection.