Processing of the bovine spongiform encephalopathy-specific prion protein by dendritic cells

Dendritic cells (DC) are suspected to be involved in transmissible spongiform encephalopathies, including bovine spongiform encephalopathy (BSE). We detected the disease-specific, protease-resistant prion protein (PrP(bse)) in splenic DC purified by magnetic cell sorting 45 days after intraperitoneal inoculation of BSE prions in immunocompetent mice. We showed that bone marrow-derived DC (BMDC) from wild-type or PrP-null mice acquired both PrP(bse) and prion infectivity within 2 h of in vitro culture with a BSE inoculum. BMDC cleared PrP(bse) within 2 to 3 days of culture, while BMDC infectivity was only 10-fold diminished between days 1 and 6 of culture, suggesting that the infectious unit in BMDC is not removed at the same rate as PrP(bse) is removed from these cells. Bone marrow-derived plasmacytoid DC and bone marrow-derived macrophages (BMM) also acquired and degraded PrP(bse) when incubated with a BSE inoculum, with kinetics very similar to those of BMDC. PrP(bse) capture is probably specific to antigen-presenting cells since no uptake of PrP(bse) was observed when splenic B or T lymphocytes were incubated with a BSE inoculum in vitro. Lipopolysaccharide activation of BMDC or BMM prior to BSE infection resulted in an accelerated breakdown of PrP(bse). Injected by the intraperitoneal route, BMDC were not infectious for alymphoid recombination-activated gene 2(0)/common cytokine gamma chain-deficient mice, suggesting that these cells are not capable of directly propagating BSE infectivity to nerve endings.     

Blood volume measurement: The comparison of pulse dye densitometry and Dill and Costill's methods

In many clinical situations, it is crucial to determine circulating blood volume (BV) easily and to repeat this measurement. The Dye DensitoGram Analyzer® (DDG, Nihon Kohden Corp) measures semi-automatically BV, using an injection of IndoCyanine Green (ICG, 10 mg), and avoiding intermittent blood samples. The DDG was used during a 90-day microgravity simulation by Head-Down-Tilt bed rest (HDT) to measure BV and compared with the calculation of the plasma volume (PV) variations according to Dill and Costill's formula (DC). Seventeen healthy volunteers were included: 8 control subjects (Co) and 9 subjects submitted to a resistive exercise counter-measure (CM). Measurements were performed, one day before HDT, on days 3 and 90 of HDT and on day 9 after HDT. A double measurement of the BV was performed to assess the repeatability of this method. On the last day of HDT a significant decrease (p < 0.05) in the PV was noted with the DDG (Co: − 12.3 ± 5.7%, CM: − 9.0 ± 5.3%) and DC; (Co: − 4.7 ± 1.8%, CM: − 6.8 ± 2.5%). A good repeatability of the technique was shown with a low intrasubjects coefficient of variation (4.95 ± 0.95%) and an acceptable intersubjects coefficient of variation (15.30 ± 1.13%). No correlation was noted between DDG and DC (r² = 0.27). The DDG gives a good repeatability, not affected by the microgravity exposure. Thanks to its capacity to measure accurately the BV within 7-10 min, this device presents major advantages for clinical use and research purpose.     

A Wnt1-regulated genetic network controls the identity and fate of midbrain-dopaminergic progenitors in vivo

Midbrain neurons synthesizing the neurotransmitter dopamine play a central role in the modulation of different brain functions and are associated with major neurological and psychiatric disorders. Despite the importance of these cells, the molecular mechanisms controlling their development are still poorly understood. The secreted glycoprotein Wnt1 is expressed in close vicinity to developing midbrain dopaminergic neurons. Here, we show that Wnt1 regulates the genetic network, including Otx2 and Nkx2-2, that is required for the establishment of the midbrain dopaminergic progenitor domain during embryonic development. In addition, Wnt1 is required for the terminal differentiation of midbrain dopaminergic neurons at later stages of embryogenesis. These results identify Wnt1 as a key molecule in the development of midbrain dopaminergic neurons in vivo. They also suggest the Wnt1-controlled signaling pathway as a promising target for new therapeutic strategies in the treatment of Parkinson's disease.     

Dehydroepiandrosterone (DHEA) is an anabolic steroid like dihydrotestosterone (DHT), the most potent natural androgen, and tetrahydrogestrinone (THG)

We have recently taken advantage of the unique power of DNA microarrays to compare the genomic expression profile of tetrahydrogestrinone (THG) with that of dihydrotestosterone (DHT), the most potent natural androgen, thus clearly demonstrating that THG is an anabolic steroid. In 2004, the U.S. Controlled Substances Act has been modified to include androstenedione (4-dione) as an anabolic steroid. However, despite the common knowledge that dehydroepiandrosterone (DHEA) is the precursor of testosterone, DHEA has been excluded from the list of anabolic steroids. We thus used the same DNA microarray technology to analyze the expression profile of practically all the 30,000 genes of the mouse genome modulated by DHEA and DHT in classical androgen-sensitive tissues. Daily subcutaneous injections of DHT (0.1mg) or DHEA (3mg) for 1 month in gonadectomized C57BL6/129 SV mice increased ventral prostate, dorsal prostate, seminal vesicle and preputial gland weight (p<0.01 for all tissues). As early as 24h after single injection of the two steroids, 878, 2681 and 14 probe sets were commonly stimulated or inhibited (p<0.01, change> or =30%), in the prostate (ventral+dorsal), seminal vesicles and preputial glands, respectively, compared to tissues from gonadectomized control animals. After 7 days of daily treatment with DHEA and DHT, 629, 919 and 562 probe sets were commonly modulated in the same tissues while after 27 days of treatment, 1195, 5127 and 2883 probe sets were modulated, respectively. In analogy with the data obtained with THG, the present microarray data provide an extremely precise and unquestionable genomic signature and proof of the androgenic/anabolic activity of DHEA. Such data add to the literature showing that DHEA is transformed into androgens in the human peripheral tissues as well as in laboratory animal species, including the monkey, thus exerting potent androgenic/anabolic activity. The present microarray approach to identify anabolic compounds is applicable to all potential androgenic/anabolic compounds.     

Blockade of tissue factor-factor X binding attenuates sepsis-induced respiratory and renal failure

Tissue factor expression in sepsis activates coagulation in the lung, which potentiates inflammation and leads to fibrin deposition. We hypothesized that blockade of factor X binding to the tissue factor-factor VIIa complex would prevent sepsis-induced damage to the lungs and other organs. Acute lung injury was produced in 15 adult baboons primed with killed Escherichia coli [1 x 10(9) colony-forming units (CFU)/kg], and then 12 h later, they were given 1 x 10(10) CFU/kg live E. coli by infusion. Two hours after live E. coli, animals received antibiotics with or without monoclonal antibody to tissue factor intravenously to block tissue factor-factor X binding. The animals were monitored physiologically for 34 h before being killed and their tissue harvested. The antibody treatment attenuated abnormalities in gas exchange and lung compliance, preserved renal function, and prevented tissue neutrophil influx and bowel edema relative to antibiotics alone (all P < 0.05). It also attenuated fibrinogen depletion (P < 0.01) and decreased proinflammatory cytokines, e.g., IL-6 and -8 (P < 0.01), in systemic and alveolar compartments. Similar protective effects of the antibody on IL-6 and -8 expression and permeability were found in lipopolysaccharide-stimulated endothelial cells. Blockade of factor X binding to the tissue factor-factor VIIa complex attenuates lung and organ injuries in established E. coli sepsis by attenuating the neutrophilic response and inflammatory pathways.     

Extracellular production of Streptomyces lividans acetyl xylan esterase A in Escherichia coli for rapid detection of activity

Acetyl xylan esterase A (AxeA) from Streptomyces lividans belongs to a large family of industrially relevant polysaccharide esterases. AxeA and its truncated form containing only the catalytically competent domain, AxeA(tr), catalyze both the deacetylation of xylan and the N-deacetylation of chitosan. This broad substrate specificity lends additional interest to their characterization and production. Here, we report three systems for extracellular production of AxeA(tr): secretion from the native host S. lividans with the native signal peptide, extracellular production in Escherichia coli with the native signal peptide, and in E. coli with the OmpA signal peptide. Over five to seven days of a shake flask culture, the native host S. lividans with the native signal peptide secreted AxeA(tr) into the extracellular medium in high yield (388 mg/L) with specific activity of 19 U/mg corresponding to a total of 7000 U/L. Over one day of shake flask culture, E. coli with the native secretion signal peptide produced 84-fold less in the extracellular medium (4.6 mg/L), but the specific activity was higher (100 U/mg) corresponding to a total of 460 U/L. A similar E. coli culture using the OmpA signal peptide, produced 10mg/L with a specific activity of 68 U/mg, corresponding to a total of 680 U/L. In 96-well microtiter plates, extracellular production with E. coli gave approximately 30 and approximately 86 microg/mL in S. lividans. Expression in S. lividans with the native signal peptide is best for high level production, while expression in E. coli using the OmpA secretion signal peptide is best for high-throughput expression and screening of variants in microtiter plate format.     

Time, from psychology to neurophysiology: a historical view

Two aspects of psychology and physiology of time are dealt with in this paper: the way time perception was increasingly studied during the 19th century by scientists, including many physicists, and the way the temporal properties of the nervous system were discovered and explored by physiologists. The neurophysiological correlation between both aspects still remains to be explained. The relationship between time consciousness and consciousness mechanisms was often guessed by philosophers and looked for by scientists. It remains a major subject of investigation in neuroscience as well as a philosophical puzzle.     

An integrated metabonomic approach to describe temporal metabolic disregulation induced in the rat by the model hepatotoxin allyl formate

The time-related metabolic events in rat liver, plasma, and urine following hepatotoxic insult with allyl formate (75 mg/kg) were studied using a combination of high-resolution liquid state and magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopic methods together with pattern recognition analysis. The metabonomics results were compared with the results of conventional plasma chemistry and histopathological assessments of liver damage. Various degrees of liver damage were observed in different animals, and this variation was reflected in all of the analyses. Furthermore, each analysis revealed a high degree of functional and structural recovery by the end of the study. The allyl formate-induced changes included hepatocellular necrosis, hepatic lipidosis, decreased liver glycogen and glucose, decreased plasma lipids, increased plasma creatine and tyrosine, increased urinary taurine and creatine, and decreased urinary TCA cycle intermediates. The observed reductions in hepatic glycogen and glucose suggest increased glucose utilization and are consistent with the expected depletion of hepatic ATP following mitochondrial impairment, assuming that there is a consequent increase in energy production from glycolysis. The increase in plasma tyrosine is consistent with impaired protein synthesis, a known consequence of ATP depletion. Partial least squares-based cross-correlation of the variation in the liver and plasma NMR profiles indicated that the allyl formate-induced increase in liver lipids correlated with the decrease in plasma lipids. This suggests disruption in lipid transport from the liver to plasma, which could arise through impaired apolipoprotein synthesis, as with ethionine.