Molecular characterisation and origin of the Coffea arabica L. genome

Restriction fragment length polymorphism (RFLP) markers were used in combination with genomic in situ hybridisation (GISH) to investigate the origin of the allotetraploid species Coffea arabica (2n = 44). By comparing the RFLP patterns of potential diploid progenitor species with those of C. arabica, the sources of the two sets of chromosomes, or genomes, combined in C. arabica were identified. The genome organisation of C. arabica was confirmed by GISH using simultaneously labelled total genomic DNA from the two putative genome donor species as probes. These results clearly suggest that C. arabica is an amphidiploid formed by hybridisation between C. eugenioides and C. canephora, or ecotypes related to these diploid species. Our results also indicate low divergence between the two constituent genomes of C. arabica and those of its progenitor species, suggesting that the speciation of C. arabica took place relatively recently. Precise localisation in Central Africa of the site of the speciation of C. arabica, based on the present distribution of the coffee species, appears difficult, since the constitution and extent of tropical forest has varied considerably during the late Quaternary period. Received: 6 June 1998 / Accepted: 10 November 1998     

Liver Dysfunction and Phosphatidylinositol-3-Kinase Signalling in Early Sepsis: Experimental Studies in Rodent Models of Peritonitis

Background

Hepatic dysfunction and jaundice are traditionally viewed as late features of sepsis and portend poor outcomes. We hypothesized that changes in liver function occur early in the onset of sepsis, yet pass undetected by standard laboratory tests.

Methods and Findings

In a long-term rat model of faecal peritonitis, biotransformation and hepatobiliary transport were impaired, depending on subsequent disease severity, as early as 6 h after peritoneal contamination. Phosphatidylinositol-3-kinase (PI3K) signalling was simultaneously induced at this time point. At 15 h there was hepatocellular accumulation of bilirubin, bile acids, and xenobiotics, with disturbed bile acid conjugation and drug metabolism. Cholestasis was preceded by disruption of the bile acid and organic anion transport machinery at the canalicular pole. Inhibitors of PI3K partially prevented cytokine-induced loss of villi in cultured HepG2 cells. Notably, mice lacking the PI3Kγ gene were protected against cholestasis and impaired bile acid conjugation. This was partially confirmed by an increase in plasma bile acids (e.g., chenodeoxycholic acid [CDCA] and taurodeoxycholic acid [TDCA]) observed in 48 patients on the day severe sepsis was diagnosed; unlike bilirubin (area under the receiver-operating curve: 0.59), these bile acids predicted 28-d mortality with high sensitivity and specificity (area under the receiver-operating curve: CDCA: 0.77; TDCA: 0.72; CDCA+TDCA: 0.87).

Conclusions

Liver dysfunction is an early and commonplace event in the rat model of sepsis studied here; PI3K signalling seems to play a crucial role. All aspects of hepatic biotransformation are affected, with severity relating to subsequent prognosis. Detected changes significantly precede conventional markers and are reflected by early alterations in plasma bile acids. These observations carry important implications for the diagnosis of liver dysfunction and pharmacotherapy in the critically ill. Further clinical work is necessary to extend these concepts into clinical practice. Please see later in the article for the Editors'' Summary     

Suppression of Drosophila cellular immunity by directed expression of the ExoS toxin GAP domain of Pseudomonas aeruginosa

We show here that transgenic Drosophila can be used to decipher the effect of a bacterial toxin on innate immunity and demonstrate the contribution of blood cells in fly resistance to bacterial infection. ExoS is a Pseudomonas aeruginosa exotoxin directly translocated into the host cell cytoplasm through the type III secretion system found in many Gram-negative bacteria. It contains a N-terminal GTPase activating (GAP) domain that prevents cytoskeleton reorganization by Rho family of GTPases in cell culture. Directed expression of the ExoS GAP domain (ExoSGAP) during fly eye morphogenesis inhibited Rac1-, Cdc42- and Rho-dependent signalling, demonstrating for the first time its activity on RhoGTPases in a whole organism. We further showed that fly resistance to P. aeruginosa infections was altered when ExoSGAP was expressed either ubiquitously or in haemocytes, but not when expressed into the fat body, the major source of NF-(kappa)B-dependent anti-microbial peptide synthesis. Fly sensitivity to infection was also observed with Gram-positive Staphylococcus aureus strain and was associated to a reduced phagocytosis capacity of ExoSGAP-expressing haemocytes. Our results highlight the major contribution of cellular immunity during the first hours after Drosophila infection by P. aeruginosa, an opportunist pathogen affecting patients with pathologies associated to a reduced leukocyte number.     

Low-dose ghrelin infusion--evidence against a hormonal role in food intake

Ghrelin is the only peripheral orexigenic peptide of gastrointestinal origin. Its preprandial increase is supposed to initiate food intake. This assumption is based on studies with intravenously infused ghrelin in rather high doses and the correlation between ghrelin levels and hunger sensations. As yet it is unclear whether or not low dose ghrelin resulting in physiological and moderately supraphysiological plasma levels has an effect on hunger sensations, the wish for food intake and / or the quantity of the meal consumed. We examined 20 normal-weight males (age 25±1.7 years, BMI 24±0.5 kg/m(2)) in a prospective double-blind randomized fashion. On two different days they obtained a ghrelin infusion 1 ng/kg/min or intravenous saline starting one hour after a standardized meal. Hunger and satiety ratings were documented by visual analogue scales. A second meal was served on demand and consumed until feeling satiated. Time point of the second meal as well as ingested calories were registered. Prior to the start of i.v. ghrelin the postprandial decrease of active plasma ghrelin by 30 pg/ml was comparable. In the controls the postprandial reduction was significant until 210 min compared to basal. With i.v. ghrelin basal levels were reached within 10 min. The maximal rise was twice basal. No effect was observed on hunger and satiety ratings. The time period between the meals and the food quantity of the second meal were similar. During ghrelin infusion glucose and growth hormone but not insulin and cortisol levels were significantly higher after the second meal compared to saline. The present data demonstrate for the first time the effect of a low dose ghrelin infusion on food intake. Neither physiological nor moderably supraphysiological ghrelin levels were associated with any change of the various food intake parameters determined. These data do not favour a hormonal role of peripheral ghrelin in the regulation of food intake.     

Second generation of BACE-1 inhibitors. Part 1: The need for improved pharmacokinetics

Inhibition of the aspartyl protease BACE-1 has the potential to deliver a disease-modifying therapy for Alzheimer’s disease. We have recently disclosed a series of transition-state mimetic BACE-1 inhibitors showing nanomolar potency in cell-based assays. Amongst them, GSK188909 (compound 2) had favorable pharmacokinetics and was the first orally bioavailable inhibitor reported to demonstrate brain amyloid lowering in an animal model. In this Letter, we describe the reasons that led us to favor a second generation of inhibitors for further in vivo studies.     

Harmonization is more important than experience—results of the first Nordic–Baltic diatom intercalibration exercise 2007 (stream monitoring)

The goal of this study was a harmonization of diatom identification and counting among diatomists from the Scandinavian and Baltic countries to improve the comparison of diatom studies in this geographical area. An analysis of the results of 25 diatomists following the European standard EN 14407 during an intercalibration exercise showed that a high similarity was achieved by harmonization and not because of a long experience with diatoms. Sources of error were wrong calibration scales, overlooking of small taxa, especially small Navicula s.l., misidentifications (Eunotia rhomboidea was mistaken for Eunotia incisa) and unclear separation between certain taxa in the identification literature. The latter was discussed during a workshop with focus on the Achnanthes minutissima group, the separation of Fragilaria capucina var. gracilis from F. capucina var. rumpens, and Nitzschia palea var. palea from N. palea var. debilis. The exercise showed also that the Swedish standard diatom method tested here worked fine with acceptable error for the indices IPS (Indice de Polluo-sensibilité Spécifique) and ACID (ACidity Index for Diatoms) when diatomists with a low similarity (Bray–Curtis <60%) with the auditor in at least one of the samples are excluded.     

Computational modelling of cancerous mutations in the EGFR/ERK signalling pathway

Background  

The Epidermal Growth Factor Receptor (EGFR) activated Extracellular-signal Regulated Kinase (ERK) pathway is a critical cell signalling pathway that relays the signal for a cell to proliferate from the plasma membrane to the nucleus. Deregulation of the EGFR/ERK pathway due to alterations affecting the expression or function of a number of pathway components has long been associated with numerous forms of cancer. Under normal conditions, Epidermal Growth Factor (EGF) stimulates a rapid but transient activation of ERK as the signal is rapidly shutdown. Whereas, under cancerous mutation conditions the ERK signal cannot be shutdown and is sustained resulting in the constitutive activation of ERK and continual cell proliferation. In this study, we have used computational modelling techniques to investigate what effects various cancerous alterations have on the signalling flow through the ERK pathway.     

The Kiddie-SADS allows a dimensional assessment of externalizing symptoms in ADHD children and adolescents

Objective of the study was the investigation of the psychometric properties of a scale derived from the Kiddie-SADS used for a dimensional assessment of externalizing symptoms in children and adolescents. The scale consists of 26 DSM-IV Kiddie-SADS items for attention deficit hyperactivity disorder (ADHD, 18 items) and oppositional defiant disorder (ODD, 8 items). Patients and their mothers were interviewed separately on the patients' symptoms during the last 2 weeks prior to interview. An ADHD-ODD sum score ranging between 0 and 26 was computed reflecting the number of fulfilled diagnostic criteria within the 2-week period under investigation. Interviews were videotaped and re-rated by an independent second rater. Additionally, mothers filled out two questionnaires on their children's symptoms (FBB-HKS, a German ADHD scale based on ICD-10 and DSM-IV criteria; strength and difficulties questionnaire, SDQ). We investigated 59 patients affected by AD(H)D according to DSM-IV recruited from our Department for Child and Adolescent Psychiatry (39 males, 20 females; mean age: M=9.66, SD=2.30). Inter-rater correlation regarding the ADHD-ODD scores was r=0.98 with no significant differences in mean sum scores between rater 1 and rater 2. Internal consistency of the ADHD-ODD scale was 0.85 (Cronbach's alpha). Item difficulties and discriminative power of the items also proved to be adequate. Convergent and discriminant validity were indicated by middle to high correlations with mother-ratings of the children's externalizing symptoms and a low correlation with ratings of internalizing symptoms. Factor analysis revealed a three-factor solution mainly covering inattentive, hyperactive and oppositional symptoms. In summary, ADHD and ODD sections of the Kiddie-SADS allow a reliable and valid dimensional assessment of externalizing symptoms in AD(H)D children and adolescents.