Secreted Phospholipase A2 Specificity on Natural Membrane Phospholipids.

The secreted phospholipase A2 (sPLA2) family contains 10 catalytically active isoforms. Current in vitro biochemical studies have shown that individual sPLA2s have distinct substrate selectivity in terms of the polar head groups or sn-2 fatty acids of their substrate phospholipids. Importantly, transgenic or knockout mice for distinct sPLA2s display nonoverlapping phenotypes, arguing that they do act on different phospholipid substrates and mobilize unique lipid metabolites in vivo. In an effort to comprehensively understand lipid metabolism driven by individual sPLA2s under pathophysiological conditions, we took advantages of mass spectrometric lipidomics technology to monitor the spatiotemporal changes in phospholipids (substrates) and products (fatty acids, lysophospholipids, and their metabolites) in tissues or cells of sPLA2-transgenic or knockout mice. The in vivo lipidomic data were compared with the in vitro activity of recombinant sPLA2s toward phospholipid mixtures extracted from the target tissues, cells, or extracellular membrane components on which sPLA2s may intrinsically act. These approaches reveal that the overall tendency in in vitro assays using natural membranes is recapitulated in several in vivo systems, often with even more selective patterns of hydrolysis. In this chapter, we will summarize current understanding of the in vivo substrate specificity of sPLA2s toward natural membrane phospholipids.

The Roles of the Secreted Phospholipase A2 Gene Family in Immunology.

Within the phospholipase A2 (PLA2) family that hydrolyzes phospholipids to yield fatty acids and lysophospholipids, secreted PLA2 (sPLA2) enzymes comprise the largest group containing 11 isoforms in mammals. Individual sPLA2s exhibit unique tissue or cellular distributions and enzymatic properties, suggesting their distinct biological roles. Although PLA2 enzymes, particularly cytosolic PLA2 (cPLA2α), have long been implicated in inflammation by driving arachidonic acid metabolism, the precise biological roles of sPLA2s have remained a mystery over the last few decades. Recent studies employing mice gene-manipulated for individual sPLA2s, in combination with mass spectrometric lipidomics to identify their target substrates and products in vivo, have revealed their roles in diverse biological events, including immunity and associated disorders, through lipid mediator-dependent or -independent processes in given microenvironments. In this review, we summarize our current knowledge of the roles of sPLA2s in various immune responses and associated diseases.

NecroX-5 suppresses IgE/Ag-stimulated anaphylaxis and mast cell activation by regulating the SHP-1-Syk signaling module.

BACKGROUND: IgE/Ag-stimulated mast cells release various pro-allergic inflammatory mediators, including histamine, eicosanoids, and pro-inflammatory cytokines. NecroX-5, a cell permeable necrosis inhibitor, showed cytoprotective effects in both in vitro and in vivo models. However, the anti-allergic effect of NecroX-5 has not yet been investigated. The aims of this study were to evaluate the anti-allergic activity of NecroX-5 in vivo and to investigate the underlying mechanism in vitro. METHODS: The anti-allergic activity of NecroX-5 was evaluated in vitro using bone marrow-derived mast cells (BMMCs) and IgE receptor-bearing RBL-2H3 or KU812 cells and in vivo using a mouse model of passive anaphylaxis. The levels of histamine, eicosanoids (PGD2 and LTC4 ), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were measured using enzyme immunoassay kits. The mechanism underlying the action of NecroX-5 was investigated using immunoblotting, immunoprecipitation, and gene knockdown techniques. RESULTS: NecroX-5 markedly inhibited mast cell degranulation and the synthesis of eicosanoids, TNF-α, and IL-6 by suppressing the activation of Syk, LAT, phospholipase Cγ1, MAP kinases, the Akt/NF-κB pathway, and intracellular Ca(2+) mobilization via the activation of phosphatase SHP-1. Oral administration of NecroX-5 effectively suppressed mast cell-dependent passive cutaneous and systemic anaphylactic reactions in a dose-dependent manner. CONCLUSIONS: NecroX-5 might be a potential candidate for the development of a novel anti-allergic agent that suppresses IgE-dependent mast cells signaling.

Primary graft dysfunction after living donor liver transplantation is characterized by delayed functional hyperbilirubinemia.

The purpose of this study is to propose a new concept of primary graft dysfunction (PGD) after living donor liver transplantation (LDLT), characterized by delayed functional hyperbilirubinemia (DFH) and a high early graft mortality rate. A total of 210 adult-to-adult LDLT grafts without anatomical, immunological or hepatitis-related issues were included. All of the grafts with early mortality (n = 13) caused by PGD in LDLT had maximum total bilirubin levels >20 mg/dL after postoperative day 7 (p < 0.001). No other factors, including prothrombin time, ammonia level or ascites output after surgery were associated with early mortality. Thus, DFH of >20 mg/dL for >seven consecutive days occurring after postoperative day 7 (DFH-20) was used to characterize PGD. DFH-20 showed high sensitivity (100%) and specificity (95.4%) for PGD with early mortality. Among the grafts with DFH-20 (n = 22), those with early mortality (n = 13) showed coagulopathy (PT-INR > 2), compared with those without mortality (p = 0.002). Pathological findings in the grafts with DFH-20 included hepatocyte ballooning and cholestasis, which were particularly prominent in the centrilobular zone. PGD after LDLT is associated with DFH-20 caused by graft, recipient and surgical factors, and increases the risk of early graft mortality.

Resolution of a reflection hologram recorded with a slit.

Resolution of the reconstructed image is evaluated for the reflection hologram recorded by use of a slit. Sharp and deep images are obtained because the resolution in the vertical direction is higher than that of the conventional reflection holograms and is independent of the size of the illuminating light source. In contrast, the resolution in the horizontal direction depends on the light-source size in this direction. The optimum source size is discussed in connection with the balance in the resolutions for both directions. A method for obtaining the vertical parallax by use of multiple slits is proposed, and application of the proposed hologram to the heads-up display is also demonstrated.

Reflection hologram for reconstructing deep images: errata.

On p. 1725 of Ref. 1, in the 20th line in the righthand column, the printed phrase "two-step time diffraction" should read as "two-step diffraction."

Reflection hologram for reconstructing deep images.

A method to record deep and blurless images as a reflection hologram is proposed. A slit was used in the recording process in the same manner as for a rainbow hologram. The reconstructed image was monocolor and could be observed from wide longitudinal angles when it was illuminated by an extended white-light source such as a fluorescent lamp. One can easily obtain multicolor images by multiplexing the holograms with different wavelengths.

Moving grating for enhanced holographic recording in cerium-doped Sr(0.6)Ba(0.4)Nb(2)O(6).

We demonstrate that holographic recording in photorefractive materials can be improved by using a moving grating to reduce energy coupling. In cerium-doped Sr(0.6)Ba(0.4)Nb(2)O(6) under an applied dc electric field, experimental and theoretical results show that the proper grating velocity can maximize the modulus and the real part of the spacecharge field while reducing the imaginary component of the space-charge field (and energy coupling) to zero. Avoiding energy transfer between the recording beams allows us to maintain maximum contrast throughout the crystal, producing a uniform, high-index-modulation grating with enhanced diffraction efficiency and superposition properties.

Moving grating and dc external field in photorefractive GaP at 633 nm.

We demonstrate that the photorefractive effect in GaP crystal at 633 nm can be enhanced using an externally applied dc field and a moving grating. A two-beam coupling gain coefficient of 2.5 cm(-1) and a steady-state phase-conjugate reflectivity of 1.9% were obtained.

Incremental recording for photorefractive hologram multiplexing.

We investigate an incremental recording technique for multiplexed hologram storage in photorefractive crystals, in which each hologram is recorded with multiple short exposures. The performance is theoretically compared with that of scheduled (single exposure per hologram) recording. Our analysis shows that this technique systematically controls the signal uniformity and can also decrease the total recording time. We present an experimental demonstration with LiNbO(3) using a binary orthogonal phase-code addressing technique.

Dynamic photorefractive optical memory.

We investigate an architectural approach to dynamic three-dimensional volume storage that circulates holograms between two photorefractive crystals. Introduction of an optical amplifier into the system increases the effective write-erase asymmetry of the crystals and permits the amplification of the recalled images. This memory architecture is experimentally shown to provide write-erase storage with robustness to multiple optical readouts.

Carbamylation of insulin and its biological activity.

A nonspecific binding reaction between cyanic acid formed from urea and protein or peptide is called carbamylation. In the present study, insulin, a peptide hormone, was subjected to carbamylation and the activity of carbamylated insulin was determined. Both immunological and biological activities of insulin changed on carbamylation. The decrease in biological activity in respect to glucose oxidation of fat cells or receptor-binding capacity of rat hepatocytes was greater than that in immunological activity.

Ultrastructure of the mandibular organ of the shrimp, Penaeus japonicus, in untreated and experimentally manipulated individuals.

The fine structure of the mandibular organ of the shrimp, Penaeus japonicus, was studied. The cells of mandibular organ contain mitochondria, smooth endoplasmic reticulum and Golgi complex. These organelles do not show any change during molt cycle. Prominent changes were observed in the cells after some steroids or proteinaceous substance. Some changes in the cells also occurred after the eyestalks were ablated. The function of the mandibular organ was considered.

Absorption of experimentally administered materials by the hepatopancreas cells of the crayfish, Procambarus clarki.

After long term starvation, the crayfish, Procambarus clarki was administered protein silver, iron lactate and olive oil, and its hepatopancreas was subsequently examined by electron microscopy. The reserve cells showed changes suggesting the absorption of these materials from the acinar lumen had taken place. In contrast, the hindgut of crayfish seemed to have no absorptive ability. In crustaceans the hepatopancreas is the largest gland in the body. The chief functions of this gland are the secretion of digestive juice into the stomach and absorption of digested food. It is also where materials which are necessary for hardening of animals that have undergone ecdysis are stored. Although these roles are commonly accepted, the absorptive ability of the gland has been rarely studied. Yonge (1924) and van Weel (1955) attempted to obtain evidence for the absorptive function of hepatopancreas cells of Nephrops norvegicus and Atya spinides using iron lactate and iron saccharate, and obtained some positive results. They used the histochemical Prussian blue test to demonstrate absorbed iron. Vonk (1960) referred to the results of a few authors who had tried to show fat deposits in reserve cells of the hepatopancreas after the administration of olive oil to the animals. But because starvation did not affect the quantity of stored fat in the hepatopancreas cells, the attempt failed to reveal the absorption of fat by the hepatopancreas. In the present paper, the authors describe the results of studies on the absorption of experimentally administered materials by hepatopancreas cells of the crayfish, Procambarus clarki, using electron microscopy.

The microvilli of the midgut epithelium in the freshwater shrimp, Caridina denticulata.

The ultrastructure of the epithelial cell microvilli of the midgut of a decapod, Caridina denticulata , was studied. The microvilli have an axial bundle of filaments extend from the tip of the microvilli deeply into the interior cytoplasm of the epithelial cells. Basal globules were present at the base of the microvilli in the premolt stage animals. The length and arrangement of the microvilli change during the molting cycle.

Effect of physical fitness and training on physiological responses to hypogravity.

The studies on the orthostatic tolerance during the hypodynamics exposure seem to be significant in connection with the selection, training and health maintenance of astronauts. Using male human subjects of various physical fitness levels, fluctuations of their physical fitness through 2 weeks of vigorous athletic training were measured in many parameters. For some of the subjects, the effects of 6 hr thermal neutral water immersion exposure in head out supine position on the physical fitness parameters and orthostatic tolerability were compared before training with after training. The results obtained were as follows: (1) Before training, orthostatic tolerability before hypodynamics exposure increased, following the physical fitness levels; the value after the hypodynamics exposure decreased in all the cases, but no differences were observed between the physical fitness levels. (2) As a result of training an increase of the physical fitness capacity was observed. The increase of orthostatic tolerability before hypodynamics exposure was noticed except for athletes. (3) Before hypodynamics exposure the urinary excretion of noradrenaline on non-athlete subjects increased as the physicsl fitness level increased. The values were decreased by physical training, the more so the better the physical fitness. After hypodynamics exposure the same relation was observed. But for athletes the values remain more stable and the decrease by hypodynamics exposure was not so distinctive. Such decreased reaction to hypodynamic conditions seems to reveal the neuro hormonal mechanism for the detrimental adaptation of athletes to hypodynamics. These results suggest that stable athletes do not always have low orthostatic tolerability, but do not respond well to hypodynamic conditions, at least from the orthostatic point of view. The mechanism seems related to sympathetic nerve activity.