No evidence for a putative involvement of platelet-activating factor in systemic lupus erythematosus without active nephritis

BACKGROUND: Platelet-activating factor (PAF) seems to be implicated in systemic lupus erythematosus (SLE) patients with associated renal diseases. AIMS: In this study, we ensured the role of PAF in SLE patients without renal complications. METHODS: Blood PAF and acetylhydrolase activity, plasma soluble phospholipase A(2), and the presence of antibodies against PAF were investigated in 17 SLE patients without active nephritis and in 17 healthy controls. RESULTS: Blood PAF levels were not different (p=0.45) between SLE patients (6.7+/-2.8 pg/ml) and healthy subjects (9.6+/-3.1 pg/ml). Plasma acetylhydrolase activity (the PAF-degrading enzyme) was significantly (p=0.03) elevated in SLE patients (57.8+/-6.4 nmol/min/ml) as compared with controls (37.9+/-2.6 nmol/min/ml). Plasma soluble phospholipase A(2) (the key enzyme for PAF formation) was not different (p=0.6) between SLE patients (59.1+/-5.1 U/ml) and controls (54.7+/-2.4 U/ml). Antibodies against PAF were detected only in 3/17 SLE patients. Flow cytometry analysis did not highlight PAF receptors on circulating leukocytes of SLE patients. CONCLUSION: This clinical study highlights no evidence for a putative important role of PAF in SLE patients without active nephritis.     

Transplasma membrane electron transport: enzymes involved and biological function

The notion of transmembrane electron transport is usually associated with mitochondria and chloroplasts. However, since the early 1970s, it has been known that this phenomenon also occurs at the level of the plasma membrane. Ever since, evidence has accumulated for the existence of a plethora of transplasma membrane electron transport enzymes. In this review, we discuss the various enzymes known, their molecular characteristics and their biological functions.     

The mitochondrial membrane potential (deltapsi(m)) in apoptosis; an update

Mitochondrial dysfunction has been shown to participate in the induction of apoptosis and has even been suggested to be central to the apoptotic pathway. Indeed, opening of the mitochondrial permeability transition pore has been demonstrated to induce depolarization of the transmembrane potential (_m), release of apoptogenic factors and loss of oxidative phosphorylation. In some apoptotic systems, loss of _m may be an early event in the apoptotic process. However, there are emerging data suggesting that, depending on the model of apoptosis, the loss of _m may not be an early requirement for apoptosis, but on the contrary may be a consequence of the apoptotic-signaling pathway. Furthermore, to add to these conflicting data, loss of _m has been demonstrated to not be required for cytochrome c release, whereas release of apoptosis inducing factor AIF is dependent upon disruption of _m early in the apoptotic pathway. Together, the existing literature suggests that depending on the cell system under investigation and the apoptotic stimuli used, dissipation of _m may or may not be an early event in the apoptotic pathway. Discrepancies in this area of apoptosis research may be attributed to the fluorochromes used to detect _m. Differential degrees of sensitivity of these fluorochromes exist, and there are also important factors that contribute to their ability to accurately discriminate changes in _m.     

The plague in Vietnam: history and inventory of collected fleas (insecta, Siphonaptera) in the inhabited zones

Ten flea species are reported in anthropic zones of Vietnam. Xenopsylla vexabilis is also here included because of it has been involved in others plague's countries. Lentistivalius klossi is the only selvatic flea known as parasite of synanthropic rats. L. klossi bispiniformis (Li and Wang, 1958), first describe from Chinese specimens, is here synonymized (syn. nov.) with the nominal subspecies.     

Low Cell Number Proteomic Analysis Using In-Cell Protease Digests Reveals a Robust Signature for Cell Cycle State Classification

Comprehensive proteome analysis of rare cell phenotypes remains a significant challenge. We report a method for low cell number MS-based proteomics using protease digestion of mildly formaldehyde-fixed cells in cellulo, which we call the “in-cell digest.” We combined this with averaged MS1 precursor library matching to quantitatively characterize proteomes from low cell numbers of human lymphoblasts. About 4500 proteins were detected from 2000 cells, and 2500 proteins were quantitated from 200 lymphoblasts. The ease of sample processing and high sensitivity makes this method exceptionally suited for the proteomic analysis of rare cell states, including immune cell subsets and cell cycle subphases. To demonstrate the method, we characterized the proteome changes across 16 cell cycle states (CCSs) isolated from an asynchronous TK6 cells, avoiding synchronization. States included late mitotic cells present at extremely low frequency. We identified 119 pseudoperiodic proteins that vary across the cell cycle. Clustering of the pseudoperiodic proteins showed abundance patterns consistent with “waves” of protein degradation in late S, at the G2&M border, midmitosis, and at mitotic exit. These clusters were distinguished by significant differences in predicted nuclear localization and interaction with the anaphase-promoting complex/cyclosome. The dataset also identifies putative anaphase-promoting complex/cyclosome substrates in mitosis and the temporal order in which they are targeted for degradation. We demonstrate that a protein signature made of these 119 high-confidence cell cycle–regulated proteins can be used to perform unbiased classification of proteomes into CCSs. We applied this signature to 296 proteomes that encompass a range of quantitation methods, cell types, and experimental conditions. The analysis confidently assigns a CCS for 49 proteomes, including correct classification for proteomes from synchronized cells. We anticipate that this robust cell cycle protein signature will be crucial for classifying cell states in single-cell proteomes.     

Antioxidative compounds isolated from the rhizomes of smaller galanga (Alpinia officinarum Hance)

Antioxidative compounds were isolated from the methanol extract of fresh rhizome of smaller galanga (Alpinia officinarum Hance). Seven phenylpropanoids (1-7) were obtained and their structures were elucidated by MS and NMR analyses. They comprised the two known compounds, (E)-p-coumaryl alcohol gamma-O-methyl ether (1) and (E)-p-coumaryl alcohol (6); and the five novel compounds, stereoisomers of (4E)-1,5-bis(4-hydroxy-phenyl)-1-methoxy-2-(methoxymethyl)-4-pentene (2a and 2b), stereoisomers of (4E)-1,5-bis(4-hydroxyphenyl)-1-ethoxy-2-(methoxymethyl)-4-pentene (3a and 3b), (4E)-1,5-bis(4-hydroxy-phenyl)-1-[(2E)-3-(4-acetoxyphenyl)-2-propenoxy]-2-(methoxymethyl)-4-pentene (4), (4E)-1,5-bis(4-hydroxyphenyl)-2-(methoxymethyl)-4-penten-1-ol (5), and (4E)-1,5-bis(4-hydroxyphenyl)-2-(hydroxymethyl)-4-penten-1-ol (7). Compounds 1-7 were detected for the first time as constituents of galanga rhizomes and exhibited antioxidative activities against the autoxidation of methyl linoleate in bulk phase.     

Characterization of VDAC1 as a plasma membrane NADH-oxidoreductase

We have recently demonstrated that voltage dependent anion selective channel~1 (porin, isoform 1) can function as a transplasma membrane NADH:ferricyanide-reductase. However, both the specific redox characteristics and the mechanism of electron transport in this enzyme presently remain unclear. Here we demonstrate that the redox capability of porin 1 is specific for ferricyanide as this same enzyme cannot reduce DCIP or cytochrome c in vitro. Furthermore, NADH-dependent ferricyanide reduction associated with VDAC1 is not sensitive to the anion channel inhibitors DIDS and dextran sulfate. However, this activity can be inhibited by thiol chelators, suggesting that at least one of the two cysteine groups present in VDAC1 are critical for electron transfer. We propose a model on how electron transport may occur in VDAC1.     

Functional characterization of the dimer linkage structure RNA of Moloney murine sarcoma virus

Several determinants that appear to promote the dimerization of murine retroviral genomic RNA have been identified. The interaction between these determinants has not been extensively examined. Previously, we proposed that dimerization of the Moloney murine sarcoma virus genomic RNAs relies upon the concentration-dependent interactions of a conserved palindrome that is initiated by separate G-rich stretches (H. Ly, D. P. Nierlich, J. C. Olsen, and A. H. Kaplan, J. Virol. 73:7255-7261, 1999). The cooperative action of these two elements was examined using a combination of genetic and antisense approaches. Dimerization of RNA molecules carrying both the palindrome and G-rich sequences was completely inhibited by an oligonucleotide complementary to the palindrome; molecules lacking the palindrome could not dimerize in the presence of oligomers that hybridize to two G-rich sequences. The results of spontaneous dimerization experiments also demonstrated that RNA molecules lacking either of the two stretches of guanines dimerized much more slowly than the full-length molecule which includes the dimer linkage structure (DLS). However, the addition of an oligonucleotide complementary to the remaining stretch of guanines restored the kinetics of dimerization to wild-type levels. The ability of this oligomer to rescue the kinetics of dimerization was dependent on the presence of the palindrome, suggesting that interactions within the G-rich regions produce changes in the palindrome that allow dimerization to proceed with maximum efficiency. Further, unsuccessful attempts to produce heterodimers between constructs lacking various combinations of these elements indicate that the G-rich regions and the palindrome do not interact directly. Finally, we demonstrate that both of these elements are important in maintaining efficient viral replication. Modified antisense oligonucleotides targeting the DLS were found to reduce the level of viral vector titer production. The reduction in viral titer is due to a decrease in the efficiency of viral genomic RNA encapsidation. Overall, our data support a dynamic model of retroviral RNA dimerization in which discrete dimerization elements act in a concerted fashion.     

Borna disease virus persistence causes inhibition of glutamate uptake by feline primary cortical astrocytes

Borna disease virus (BDV), a nonsegmented, negative-stranded (NNS) RNA virus, causes central nervous system (CNS) disease in a broad range of vertebrate species, including felines. Both viral and host factors contribute to very diverse clinical and pathological manifestations associated with BDV infection. BDV persistence in the CNS can cause neurobehavioral and neurodevelopmental abnormalities in the absence of encephalitis. These BDV-induced CNS disturbances are associated with altered cytokine and neurotrophin expression, as well as cell damage that is very restricted to specific brain regions and neuronal subpopulations. BDV also targets astrocytes, resulting in the development of prominent astrocytosis. Astrocytes play essential roles in maintaining CNS homeostasis, and disruption of their normal activities can contribute to altered brain function. Therefore, we have examined the effect of BDV infection on the astrocyte's physiology. We present here evidence that BDV can establish a nonlytic chronic infection in primary cortical feline astrocytes that is associated with a severe impairment in the astrocytes' ability to uptake glutamate. In contrast, the astrocytes' ability to uptake glucose, as well as their protein synthesis, viability, and rate of proliferation, was not affected by BDV infection. These findings suggest that, in vivo, BDV could also affect an important astrocyte function required to prevent neuronal excitotoxicity. This, in turn, might contribute to the neuropathogenesis of BDV.