Programmed cell death (PCD) is one of the important terminal paths for the cells of metazoans, and is involved in a variety of biological events that include morphogenesis, maintenance of tissue ...homeostasis, and elimination of harmful cells. Dysfunction of PCD leads to various diseases in humans, including cancer and several degenerative diseases. Apoptosis is not the only form of PCD. Recent studies have provided evidence that there is another mechanism of PCD, which is associated with the appearance of autophagosomes and depends on autophagy proteins. This form of cell death most likely corresponds to a process that has been morphologically defined as autophagic PCD. The present review summarizes recent experimental evidence about autophagic PCD and discusses some aspects of this form of cell death, including the mechanisms that may distinguish autophagic death from the process of autophagy involved in cell survival.
Farmyard manure (FYM) - mixtures of animal droppings, crop residues, and fodder that are piled nearby homesteads - is a major nutrient source for smallholder farmers in Sub-Saharan Africa. However, ...its application effect has not been fully understood on typical P-deficient soils in tropics and in particular under anaerobic conditions. This study assessed the effect of FYM on irrigated rice in relation to soil properties - oxalate-extractable P (P
Ox
), pH, and total C (TotC) - that are important indicators of soil P deficiency in the region. The first pot experiment was conducted with a factorial combination of FYM (0 and 20 g kg
-1
) and mineral P (0 and 100 mg kg
-1
) applications using six paddy soils differing in the aforementioned soil properties. The second pot experiment was conducted in a factorial combination of FYM and mineral P using the isotope dilution technique. In both experiments, the effect of FYM application on biomass and P uptake of rice per P applied was nearly equivalent to that of mineral P and was greater in soils with lower TotC and lower pH with negligible effect of P
Ox
. The isotope tracing suggested that the FYM application might increase rice P uptake by solubilizing non-labile P pools in soils while mineral P was directly used by rice from labile P pools. The results indicated that the FYM should be most effective in soils with low TotC and low pH, and its application could enable the use of insoluble P pools in soils and enhance P uptake of rice under P-deficient and anaerobic conditions.
Programmed cell death is a crucial process in the normal development and physiology of metazoans, and it can be divided into several categories that include type I death (apoptosis) and type II death ...(autophagic cell death). The Bcl-2 family proteins are well-characterized regulators of apoptosis, among which multidomain pro-apoptotic members (such as Bax and Bak) function as a mitochondrial gateway at which various apoptotic signals converge. Although embryonic fibroblasts from Bax/Bak double-knockout (DKO) mice are resistant to apoptosis, we have previously reported that these cells still die by autophagy in response to various death stimuli. In this study, we found that jun N-terminal kinase (JNK) was activated in etoposide- and staurosporine-treated, but not serum-starved, Bax/Bak DKO cells, and that autophagic cell death was suppressed by the addition of a JNK inhibitor and by a dominant-negative mutant of JNK. Studies with sek1(-/-)mkk7(-/-) cells revealed that disruption of JNK prevented the induction of autophagic cell death. Co-activation of JNK and autophagy induced autophagic cell death. Activation of JNK occurred downstream of the induction of autophagy, and was dependent on the autophagic process. These results indicate that JNK activation is crucial for the autophagic death of Bax/Bak DKO cells.
Conventional high-temperature reactions limit the control of coordination polyhedra in transition-metal oxides to those obtainable within the bounds of known coordination geometries for a given ...transition metal. For example, iron atoms are almost exclusively coordinated by three-dimensional polyhedra such as tetrahedra and octahedra. However, recent works have shown that binary metal hydrides act as reducing agents at low temperatures, allowing access to unprecedented structures. Here we show the reaction of a perovskite SrFeO3 with CaH2 to yield SrFeO2, a new compound bearing a square-planar oxygen coordination around Fe2+. SrFeO2 is isostructural with 'infinite layer' cupric oxides, and exhibits a magnetic order far above room temperature in spite of the two-dimensional structure, indicating strong in-layer magnetic interactions due to strong Fe d to O p hybridization. Surprisingly, SrFeO2 remains free from the structural instability that might well be expected at low temperatures owing to twofold orbital degeneracy in the Fe2+ ground state with D4h point symmetry. The reduction and the oxidation between SrFeO2 and SrFeO3 proceed via the brownmillerite-type intermediate SrFeO2.5, and start at the relatively low temperature of ∼400 K, making the material appealing for a variety of applications, including oxygen ion conduction, oxygen gas absorption and catalysis.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Enhanced coupling of material properties offers new fundamental insights and routes to multifunctional devices. In this context 5d oxides provide new paradigms of cooperative interactions that drive ...novel emergent behaviour. This is exemplified in osmates that host metal-insulator transitions where magnetic order appears intimately entwined. Here we consider such a material, the 5d perovskite NaOsO3, and observe a coupling between spin and phonon manifested in a frequency shift of 40 cm(-1), the largest measured in any material. The anomalous modes are shown to involve solely Os-O interactions and magnetism is revealed as the driving microscopic mechanism for the phonon renormalization. The magnitude of the coupling in NaOsO3 is primarily due to a property common to all 5d materials: the large spatial extent of the ion. This allows magnetism to couple to phonons on an unprecedented scale and in general offers multiple new routes to enhanced coupled phenomena in 5d materials.
The Bcl-2 family of proteins consists of anti-apoptotic and pro-apoptotic members, which determine the life or death of cells by altering mitochondrial membrane permeability. Pro-apoptotic Bcl-2 ...family members increase mitochondrial membrane permeability, resulting in the release of mitochondrial apoptogenic factors such as cytochrome c that activates death proteases called caspases, whereas anti-apoptotic family members prevent this increase of mitochondrial membrane permeability. The release of cytochrome c is central to apoptotic signal transduction in mammals, and has been studied extensively, leading to the development of several models for cytochrome c release including rupture of the mitochondrial outer membrane and involvement of specific channels. This article describes the important role of a mitochondrial outer membrane channel, the voltage-dependent anion channel (VDAC), in apoptogenic cytochrome c release and its regulation by Bcl-2 family members, and also discusses the molecular architecture of the life - death switch in mammalian cells. Cell Death and Differentiation (2000) 7, 1174 - 1181
Abstract
Cavitation instabilities such as rotating cavitation and cavitation surge often occur in high speed turbopumps. In the present study, numerical simulation of cavitation surge, which ...numerically solves the one-dimensional momentum and continuity equations with modelled dynamic cavitation characteristics, is conducted. The phase lag of cavity response against the inlet pressure and the suction flow rate variations is modeled in the form of the first-order lag system considering that the frequency of cavitation surge is small. Differently from linear stability analysis made in our previous study, the equations are solved in time domain with retaining some of non-linear terms. The method is validated through the comparison with the stability analysis. Then the effect of phase lags in dynamic cavitation characteristics is examined.
In patients with ischemic stroke, DWI lesions can occasionally be reversed by reperfusion therapy. This study aimed to ascertain the relationship between ADC levels and DWI reversal in patients with ...acute ischemic stroke who underwent recanalization treatment.
We conducted a retrospective cohort study in patients with acute ischemic stroke who underwent endovascular mechanical thrombectomy with successful recanalization between April 2017 and March 2021. DWI reversal was assessed through follow-up MR imaging approximately 24 hours after treatment.
In total, 118 patients were included. DWI reversal was confirmed in 42 patients. The ADC level in patients with reversal was significantly higher than that in patients without reversal. Eighty-three percent of patients with DWI reversal areas had mean ADC levels of ≥520 × 10
mm
/s, and 71% of patients without DWI reversal areas had mean ADC levels of <520 × 10
mm
/s. The mean ADC threshold was 520 × 10
mm
/s with a sensitivity and specificity of 71% and 83%, respectively. In multivariate analysis, the mean ADC level (OR, 1.023; 95% CI, 1.013-1.033;
< .0001) was independently associated with DWI reversal. Patients with DWI reversal areas had earlier neurologic improvement (NIHSS at 7 days) than patients without reversal areas (
< .0001).
In acute ischemic stroke, the ADC value is independently associated with DWI reversal. Lesions with a mean ADC of ≥520 × 10
mm
/s are salvageable by mechanical thrombectomy, and DWI reversal areas regain neurologic function. The ADC value is easily assessed and is a useful tool to predict viable lesions.
The mechanisms of bleaching of discolored coronal teeth using hydrogen peroxide (H
2O
2) were investigated. In a scanning–electron-microscopy study, the intertubular dentin and peritubular dentin ...were dissolved by high concentrations of H
2O
2, which is used for bleaching. The X-ray diffraction study showed that hydroxyapatite was not influenced by H
2O
2. In an electron–spin-resonance study, more hydroxyl radical (· OH) was detected as the H
2O
2 concentration was increased. When amino acids that are core components of dentin proteins, such as proline and alanine, were added to H
2O
2, the generation of · OH decreased, but there was no change when glycine was added. A nuclear–magnetic-resonance study showed that proline was degraded completely by H
2O
2, the structure of alanine changed slightly, and glycine was not affected by H
2O
2. It is suggested that H
2O
2 and · OH do not influence the inorganic tissue of dentin but attack the organic component of dentin. These facts suggest that · OH has the main role in tooth bleaching with H
2O
2.
Spin transition has attracted the interest of researchers in various fields since the early 1930s, with thousands of examples now recognized, including those in minerals and biomolecules. However, so ...far the metal centres in which it has been found to occur are almost always octahedral six-coordinate 3d(4) to 3d(7) metals, such as Fe(II). A five-coordinate centre is only rarely seen. Here we report that under pressure SrFe(II)O(2), which features a four-fold square-planar coordination, exhibits a transition from high spin (S = 2) to intermediate spin (S = 1). This is accompanied by a transition from an antiferromagnetic insulating state to a ferromagnetic so-called half-metallic state: only half of the spin-down (d(xz),d(yz)) states are filled. These results highlight the square-planar coordinated iron oxides as a new class of magnetic and electric materials.
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