Proof-of-concept human laboratory study for protracted abstinence in alcohol dependence: effects of gabapentin

There is a need for safe medications that can effectively support recovery by treating symptoms of protracted abstinence that may precipitate relapse in alcoholics, e.g. craving and disturbances in sleep and mood. This proof-of-concept study reports on the effectiveness of gabapentin 1200 mg for attenuating these symptoms in a non-treatment-seeking sample of cue-reactive, alcohol-dependent individuals. Subjects were 33 paid volunteers with current Diagnostic and Statistical Manual of Mental Disorders-IV alcohol dependence and a strength of craving rating 1 SD or greater for alcohol than water cues. Subjects were randomly assigned to gabapentin or placebo for 1 week and then participated in a within-subjects trial where each was exposed to standardized sets of pleasant, neutral and unpleasant visual stimuli followed by alcohol or water cues. Gabapentin was associated with significantly greater reductions than placebo on several measures of subjective craving for alcohol as well as for affectively evoked craving. Gabapentin was also associated with significant improvement on several measures of sleep quality. Side effects were minimal, and gabapentin effects were not found to resemble any major classes of abused drugs. Results suggest that gabapentin may be effective for treating the protracted abstinence phase in alcohol dependence and that a randomized clinical trial would be an appropriate next step. The study also suggests the value of cue-reactivity studies as proof-of-concept screens for potential antirelapse drugs.     

Characterization of PR-10 genes from eight Betula species and detection of Bet v 1 isoforms in birch pollen

Background  

Bet v 1 is an important cause of hay fever in northern Europe. Bet v 1 isoforms from the European white birch (Betula pendula) have been investigated extensively, but the allergenic potency of other birch species is unknown. The presence of Bet v 1 and closely related PR-10 genes in the genome was established by amplification and sequencing of alleles from eight birch species that represent the four subgenera within the genus Betula. Q-TOF LC-MS^E was applied to identify which PR-10/Bet v 1 genes are actually expressed in pollen and to determine the relative abundances of individual isoforms in the pollen proteome.     

Biphasic ethylene production during the hypersensitive response in Arabidopsis: A window into defense priming mechanisms?

The hypersensitive response (HR) is a cell death phenomenon associated with localized resistance to pathogens. Biphasic patterns in the generation of H₂O₂, salicylic acid and ethylene have been observed in tobacco during the early stages of the HR. These biphasic models reflect an initial elicitation by pathogen-associated molecular patterns followed by a second phase, induced by pathogen-encoded avirulence gene products. The first phase has been proposed to potentiate the second, to increase the efficacy of plant resistance to disease. This potentiation is comparable to the “priming” of plant defenses which is seen when plants display systemic resistance to disease. The events regulating the generation of the biphasic wave, or priming, remains obscure, however recently we demonstrated a key role for nitric oxide in this process in a HR occurring in tobacco. Here we use laser photoacoustic detection to demonstrate that biphasic ethylene production also occurs during a HR occurring in Arabidopsis. We suggest that ethylene emanation during the HR represents a ready means of visualising biphasic events during the HR and that exploiting the genomic resources offered by this model species will facilitate the development of a mechanistic understanding of potentiating/priming processes.Key words: hypersensitive response, biphasic patterns, potentiation, defense priming, ethylene, ArabidopsisThe Hypersensitive Response (HR) is a cell death process which occurs at the site of attempted pathogen attack and which has been associated with host resistance.¹ Much work on the regulation of the HR has indicated the importance of H₂O₂,² and NO.³ A feature of H₂O₂ generation during the HR is its biphasic pattern (Fig. 1A). The first rise reflects elicitation by pathogen-associated molecular patterns (PAMPs)⁴ and the second reflects the interaction between a pathogen-encoded avirulence (avr) gene product with a plant resistance (R) gene. A key aspect of the first rise is the initiation of salicylic acid (SA) synthesis which potentiates the second rise and hence the potency of plant defense and the HR.⁵Open in a separate windowFigure 1Patterns of defense signal generation during the Pseudomonas syringae pv. phaseolicola elicited-hypersensitive response in tobacco (Nicotiana tabacum). Generation of (A) H₂O₂ (●, Mur¹⁸); (B) nitric oxide (◇; Mur¹² (C) salicylic acid (SA, ■¹⁹) and (D) ethylene (○ Mur⁹) during a HR elicited by Pseudomonas syringae pv. phaseolicola (Psph) in tobacco cv. Samsun NN. In (A) a phase where SA acts to augment the second rise in H₂O₂—the potentiation phase—is highlighted. The potentiation phase is likely to be similar to defense “priming”.⁶ Methodological details are contained within the appropriate references. (E) A possible model for biphasic defense signal regulation during the Psph-elicited HR in tobacco. During an initial phase NO and H₂O₂ act to initiate SA biosynthesis, where SA and NO act to initiate a “H₂O₂ biphasic switch”. This could initially suppress both SA and the H₂O₂ generation but subsequently acts to potentiate a second phase of H₂O₂ generation. This in turn increases SA biosynthesis which could act with NO to initiate the “C₂H₄ biphasic switch” to potentiate ethylene production. These (and other) signals contribute to initiation of the HR and SAR.This potentiation mechanism appears to be similar to defense priming; when whole plants display systemic resistance to disease as opposed to a localized resistance against pathogens. Priming can be initiated (the “primary stimulus”) following attack with a necrotizing pathogen (leading to “systemic acquired resistance”, SAR) or non-pathogenic rhizosphere bacteria (to confer “induced systemic resistance”, ISR). In the primed state a plant stimulates a range of plant defense genes, produces anti-microbial phytoalexins and deposits cell wall strengthening molecules, but only on imposition of a “secondary stimulus”.⁶ Such secondary stimuli include SA³ or PAMPs⁷ and is likely to be mechanistically similar to the potentiation step in the biphasic pattern of H₂O₂ generation (shaded in Fig. 1A). Accordingly, the two phases in the biphasic wave represent primary and secondary stimuli in priming.Highlighting a similarity between local HR-based events and priming, adds further impetus to efforts aiming to describe the underlying mechanism(s), however both phenomena remain poorly understood. Besides SA, both jasmonates and abscisic acid (ABA) have been shown to prime defenses as have a range of non-plant chemicals, with β-aminobutyric acid (BABA) being perhaps most widely used.^6,8 Mutants which fail to exhibit BABA-mediated potentiation were defective in either a cyclin-dependent kinase-like protein, a polyphosphoinositide phosphatase or an ABA biosynthetic enzyme.⁸We have recently investigated biphasic ethylene production during the HR in tobacco elicited by the nonhost HR-eliciting bacterial pathogen Pseudomonas syringae pv. phaseolicola.⁹ As with H₂O₂ generation, this pattern reflected PAMP-and AVR-dependent elicitation events and included a SA-mediated potentiation stage. Crucially, we also showed that NO was a vital component in the SA-potentiation mechanism. When this finding is integrated with our other measurements of defense signal generation in the same host-pathogen system the complexity in the signaling network is revealed (Fig. 1). NO generation (Fig. 1B) appeared to be coincident with the first rise in H₂O₂ (Fig. 1A) which initiated SA biosynthesis^10,11 and together would contribute to the first small, but transient, rise in that hormone (Fig. 1C). In line with established models⁵ this momentary rise in SA coincides with the potentiation phase (shaded in Fig. 1A) required to augment the second rise in ROS. However, ethylene production seems to be correlated poorly with the patterns of NO, H₂O₂ and SA (Fig. 1D). Nevertheless, biphasic ethylene production was found to reflect PAMP and AVR-dependent recognition and included a SA-mediated potentiation step.⁹ Hence, ethylene production could be used as a post-hoc indicator of the potentiation mechanism. Therefore, our discovery that the second wave of ethylene production—a “biphasic switch”—is influenced by NO acting with SA could also be relevant to the H₂O₂ generation. Significantly, the second phases in both H₂O₂ and ethylene production occur exactly where SA and NO production coincides; in the case of H₂O₂ generation 2–4 h post challenge and with ethylene 6 h onwards (Fig. 1E).Thus, ethylene production represents a readily assayable marker to indicate perturbations in the underlying biphasic and possible priming mechanisms. As we have demonstrated, laser photoacoustic detection (LAPD) is a powerful on-line approach to determine in planta ethylene production in tobacco^9,12 but any mechanistic investigations would be greatly facilitated if the genetic resources offered by the model species Arabidopsis could be exploited.To address this, Arabidopsis Col-0 rosettes were vacuum infiltrated with either Pseudomonas syringae pv. tomato (Pst) avrRpm1 (HR-eliciting), the virulent Pst strain and the non-HR eliciting and non-virulent Pst hrpA strain. Ethylene production was monitored by LAPD (Fig. 2A). Significantly, Pst avrRpm1 initiated a biphasic pattern of ethylene production whose kinetics were very similar to that seen in tobacco (compare Figs. 2A with ​with1D).1D). Inoculations with Pst and Pst hrpA only displayed the first PAMP-dependent rise in ethylene production. Thus, these data establish that Arabidopsis can be used to investigate biphasic switch mechanism(s) in ethylene production during the HR and possibly defense priming. When considering such mechanisms, it is relevant to highlight the work of Foschi et al.¹³ who observed that biphasic activation of a monomeric G protein to cause phase-specific activation of different kinase cascades. Interestingly, ethylene has been noted to initiate biphasic activation of G proteins and kinases in Arabidopsis, although differing in kinetics to the phases seen during the HR.¹⁴ Further, plant defense priming has been associated with the increased accumulation of MAP kinase protein.⁶Open in a separate windowFigure 2Ethylene in the Pseudomonas syringae pv. tomato elicited-hypersensitive response in Arabidopsis thaliana. (A) Ethylene production from 5 week old short day (8 h light 100 µmol.m².sec⁻¹) grown Arabidopsis rosette leaves which were vacuum infiltrated with bacterial suspensions (2 × 10⁶ colony forming units.ml⁻¹) of Pseudomonas syringae pv. tomato (Pst) strains detected using laser photoacoustic detection (LAPD). Experimental details of the ethylene detection by LAPD are detailed in Mur et al.⁹ The intercellular spaces in leaves were infiltrated with the HR-eliciting strain Pst avrRpm1, (■), the virulent strain Pst (△) or the non-virulent and non-HR eliciting derivative, Pst hrpA (◇). (B) The appearance of Arabidopsis Col-0 and etr1-1 leaves at various h following injection with 2 × 10⁶ c.f.u.mL⁻¹ with of Pst avrRpm1. (C) Explants (1 cm diameter discs) from Arabidopsis leaf areas infiltrated with suspensions of Pst avrRpm1 were placed in a 1.5 cm diameter well, bathed in 1 mL de-ionized H₂O. Changes in the conductivity of the bathing solution, as an indicator of electrolyte leakage from either wild type Col-0 (◆), mutants which were compromised in ethylene signaling; etr1-1 (□), ein2-2 (▲) or which overproduced ethylene; eto2-1 (●) were measured using a conductivity meter. Methodological details are set out in Mur et al.⁹A further point requires consideration; the role of ethylene as a direct contributor to plant defense.¹⁵ The contribution of ethylene to the HR has been disputed,¹⁶ but in tobacco we have observed that altered ethylene production influenced the formation of a P. syringae pv. phaseolicola elicited HR.⁹ In Arabidopsis, cell death in the ethylene receptor mutant etr1-1 following inoculation with Pst avrRpm1 is delayed compared to wild type (Fig. 2B). When electrolyte leakage was used to quantify Pst avrRpm1 cell death, both etr1-1 and the ethylene insensitive signaling mutant ein2-1 exhibited slower death than wild-type but in the ethylene overproducing mutant eto2, cell death was augmented (Fig. 2C). These data indicate that ethylene influences the kinetics of the HR.Taking these data together we suggest that the complexity of signal interaction during the HR or in SAR/ISR could be further dissected by combining the genetic resources of Arabidopsis with measurements of ethylene production using such sensitive approaches as LAPD.     

IFNγ Response to Mycobacterium tuberculosis,Risk of Infection and Disease in Household Contacts of Tuberculosis Patients in Colombia

Objectives

Household contacts (HHCs) of pulmonary tuberculosis patients are at high risk of Mycobacterium tuberculosis infection and early disease development. Identification of individuals at risk of tuberculosis disease is a desirable goal for tuberculosis control. Interferon-gamma release assays (IGRAs) using specific M. tuberculosis antigens provide an alternative to tuberculin skin testing (TST) for infection detection. Additionally, the levels of IFNγ produced in response to these antigens may have prognostic value. We estimated the prevalence of M. tuberculosis infection by IGRA and TST in HHCs and their source population (SP), and assessed whether IFNγ levels in HHCs correlate with tuberculosis development.

Methods

A cohort of 2060 HHCs was followed for 2–3 years after exposure to a tuberculosis case. Besides TST, IFNγ responses to mycobacterial antigens: CFP, CFP-10, HspX and Ag85A were assessed in 7-days whole blood cultures and compared to 766 individuals from the SP in Medellín, Colombia. Isoniazid prophylaxis was not offered to child contacts because Colombian tuberculosis regulations consider it only in children under 5 years, TST positive without BCG vaccination.

Results

Using TST 65.9% of HHCs and 42.7% subjects from the SP were positive (OR 2.60, p<0.0001). IFNγ response to CFP-10, a biomarker of M. tuberculosis infection, tested positive in 66.3% HHCs and 24.3% from the SP (OR = 6.07, p<0.0001). Tuberculosis incidence rate was 7.0/1000 person years. Children <5 years accounted for 21.6% of incident cases. No significant difference was found between positive and negative IFNγ responders to CFP-10 (HR 1.82 95% CI 0.79–4.20 p = 0.16). However, a significant trend for tuberculosis development amongst high HHC IFNγ producers was observed (trend Log rank p = 0.007).

Discussion

CFP-10-induced IFNγ production is useful to establish tuberculosis infection prevalence amongst HHC and identify those at highest risk of disease. The high tuberculosis incidence amongst children supports administration of chemoprohylaxis to child contacts regardless of BCG vaccination.     

The human collagen beta(1-O)galactosyltransferase,GLT25D1, is a soluble endoplasmic reticulum localized protein

Background  

Glycosyl transferases transfer glycosyl groups onto their substrate. Localization partially defines their function. Glycosyl transferase 25 domain 1 (GLT25D1) was recently shown to have galactosyltransferase activity towards collagens and another well known substrate, mannose binding lectin (MBL). To gain more insight in the role of galactosylation of lysines in the Gly-X-Lys repeats of collagenous proteins, we investigated the subcellular localization of GLT25D1.     

New cytotoxic furoquinones obtained from terpenyl-1,4-naphthoquinones and 1,4-anthracenediones

A series of new furoterpenyl-1,4-naphtho(anthra)quinones have been prepared via oxidative cyclization of the corresponding 2-hydroxy-3-butenyl-1,4-naphtho(anthra)quinones. Depending on the reaction conditions the 1,2-quinones or the 1,4-quinones were obtained. Several new furo-1,4-anthraquinones were also obtained by condensation of 2,3-dichloroquinones with 1,3-dicarbonyls. The compounds synthesized have been evaluated for their cytotoxicity against neoplastic cell lines, some of them being effective below the micromolar level.     

Synthesis of Sansalvamide A derivatives and their cytotoxicity in the MSS colon cancer cell line HT-29

We report the synthesis of thirty-six Sansalvamide A derivatives, and their biological activity against colon cancer HT-29 cell line, a microsatellite stable (MSS) colon cancer cell-line. The thirty-six compounds can be divided into three subsets, where the first subset of compounds contains L-amino acids, the second subset contains D-amino acids, and the third subset contains both D- and L-amino acids. Five compounds exhibited excellent inhibitory activity (>75% inhibition). The structure-activity relationship (SAR) of the compounds established that a single D-amino acid in position 2 or 3 gave up to a 10-fold improved cytotoxicity over Sansalvamide A peptide. This work highlights the importance of residues 2 and 3 and the role of D-amino acids in the extraordinary SAR for this compound class.     

Exercise Training Prevents Regain of Visceral Fat for 1 Year Following Weight Loss

The purpose of this study was to determine what effect aerobic and resistance exercise training has on gain of visceral fat during the year following weight loss. After being randomly assigned to aerobic training, resistance training, or no exercise training, 45 European‐American (EA) and 52 African‐American (AA) women lost 12.3 ± 2.5 kg on a 800 kcal/day diet. Computed tomography was used to measure abdominal subcutaneous and visceral adipose tissue, whereas total fat and regional fat (leg, arm, and trunk) were measured by dual energy X‐ray absorptiometry after weight loss and 1 year following the weight loss. Because not all the subjects adhered to the 2 time/week 40 min/day exercise training during the 1‐year follow‐up, subjects were divided into five groups for analysis: aerobic adherers, aerobic nonadherers, resistance adherers, resistance nonadherers, and no exercise. No significant differences were observed between the aerobic training and resistance training adherers for any variable. However, the aerobic (3.1 kg) and resistance (3.9 kg) exercise adherers gained less weight than any of the other three groups (all >6.2 kg). In addition, the two exercise adherence groups did not significantly increase visceral fat (<0.8%) as compared with the 38% increase for the two nonadhering exercise groups and the 25% for the nonexercise group. In conclusion, as little as 80 min/week aerobic or resistance training had modest positive effects on preventing weight regain following a diet‐induced weight loss. More importantly, both aerobic and resistance training prevented regain of potentially harmful visceral fat.