Regulation of replicative histone RNA metabolism by the histone chaperone ASF1

In S phase, duplicating and assembling the whole genome into chromatin requires upregulation of replicative histone gene expression. Here, we explored how histone chaperones control histone production in human cells to ensure a proper link with chromatin assembly. Depletion of the ASF1 chaperone specifically decreases the pool of replicative histones both at the protein and RNA levels. The decrease in their overall expression, revealed by total RNA sequencing (RNA-seq), contrasted with the increase in nascent/newly synthesized RNAs observed by 4sU-labeled RNA-seq. Further inspection of replicative histone RNAs showed a 3' end processing defect with an increase of pre-mRNAs/unprocessed transcripts likely targeted to degradation. Collectively, these data argue for a production defect of replicative histone RNAs in ASF1-depleted cells. We discuss how this regulation of replicative histone RNA metabolism by ASF1 as a "chaperone checkpoint" fine-tunes the histone dosage to avoid unbalanced situations deleterious for cell survival.

Enantioselective C-H Arylation for Axially Chiral Heterobiaryls

An enantioselective palladium-catalyzed C-H arylation of functionalized pyrazoles/triazoles/imidazoles is developed, affording a variety of axially chiral ortho-nitro/formyl-substituted heterobiaryls with excellent enantioselectivities and good yields. The method features a deuterated P-chiral phosphorus ligand CD3-AntPhos, a broad substrate scope of functionalized heterobiaryls, mild reaction conditions, and low palladium loadings.

Directed regioselective ortho,ortho'-magnesiations of aromatics and heterocycles using sBu2Mg in toluene

Aryl azoles are ubiquitous as bioactive compounds and their regioselective functionalization is of utmost synthetic importance. Here, we report the development of a toluene-soluble dialkylmagnesium base sBu2Mg. This new reagent allows mild and regioselective ortho-magnesiations of various N-arylated pyrazoles and 1,2,3-triazoles as well as arenes bearing oxazoline, phosphorodiamidate or amide directing groups. The resulting diarylmagnesium reagents were further functionalized either by Pd-catalyzed arylation or by trapping reactions with a broad range of electrophiles (aldehydes, ketones, allylic halides, acyl chlorides, Weinreb amides, aryl halides, hydroxylamine benzoates, terminal alkynes). Furthermore, several double ortho,ortho'-magnesiations were realized in the case of aryl oxazolines, N-aryl pyrazoles as well as 2-aryl-2H-1,2,3-triazoles by simply repeating the magnesiation/electrophile trapping sequence allowing the preparation of valuable 1,2,3-functionalized arenes.

PRELIMINARY INVESTIGATIONS OF TRANSPORT IN HETEROGENEOUS RANDOM MEDIA

Random media emerge in several applications in reactor physics and safety analysis. Most often, models of stochastic media assume spatial homogeneity, whereas real-world complex materials, such as fuel chunks resulting from core degradation, typically display apparent heterogeneities. In a series of previous works, we have shown that stochastic tessellations can be successfully used in order to describe the material properties of several classes of random media. In this paper we extend these results to the case of heterogeneous random media by using Voronoi tessellations with space-dependent seed distributions, allowing for spatial gradients.

Regioselective functionalization of aryl azoles as powerful tool for the synthesis of pharmaceutically relevant targets

Aryl azole scaffolds are present in a wide range of pharmaceutically relevant molecules. Their ortho-selective metalation at the aryl ring is challenging, due to the competitive metalation of the more acidic heterocycle. Seeking a practical access to a key Active Pharmaceutical Ingredient (API) intermediate currently in development, we investigated the metalation of 1-aryl-1H-1,2,3-triazoles and other related heterocycles with sterically hindered metal-amide bases. We report here a room temperature and highly regioselective ortho-magnesiation of several aryl azoles using a tailored magnesium amide, TMPMgBu (TMP = 2,2,6,6-tetramethylpiperidyl) in hydrocarbon solvents followed by an efficient Pd-catalyzed arylation. This scalable and selective reaction allows variation of the initial substitution pattern of the aryl ring, the nature of the azole moiety, as well as the nature of the electrophile. This versatile method can be applied to the synthesis of bioactive azole derivatives and complements existing metal-mediated ortho-functionalizations.

Aryl azoles are common scaffolds in pharmaceutically relevant molecules. Here, the authors report the mild and highly regioselective ortho magnesiation of aryl azoles using a tailored magnesium amide base in hydrocarbon solvents followed by an efficient Pd-catalyzed arylation.

Characterizing the interplay between gene nucleotide composition bias and splicing

BACKGROUND

Nucleotide composition bias plays an important role in the 1D and 3D organization of the human genome. Here, we investigate the potential interplay between nucleotide composition bias and the regulation of exon recognition during splicing.

RESULTS

By analyzing dozens of RNA-seq datasets, we identify two groups of splicing factors that activate either about 3200 GC-rich exons or about 4000 AT-rich exons. We show that splicing factor-dependent GC-rich exons have predicted RNA secondary structures at 5' ss and are dependent on U1 snRNP-associated proteins. In contrast, splicing factor-dependent AT-rich exons have a large number of decoy branch points, SF1- or U2AF2-binding sites and are dependent on U2 snRNP-associated proteins. Nucleotide composition bias also influences local chromatin organization, with consequences for exon recognition during splicing. Interestingly, the GC content of exons correlates with that of their hosting genes, isochores, and topologically associated domains.

CONCLUSIONS

We propose that regional nucleotide composition bias over several dozens of kilobase pairs leaves a local footprint at the exon level and induces constraints during splicing that can be alleviated by local chromatin organization at the DNA level and recruitment of specific splicing factors at the RNA level. Therefore, nucleotide composition bias establishes a direct link between genome organization and local regulatory processes, like alternative splicing.

Preparation of 2'-Deoxy-2'-spirocyclopropylcytidine via an Alternative Cyclopropanation Reaction

Herein we report the preparation of 2'-deoxy-2'-spirocyclopropylcytidine via an alternative cyclopropanation reaction starting from γ-silyl tertiary alcohols. Activation of the hydroxyl function with thionyl chloride in the presence of 4-DMAP allows the ring-closing step under mild conditions. Participation of the uracil moiety in the cyclization step is proposed.

Interplay between coding and exonic splicing regulatory sequences

The inclusion of exons during the splicing process depends on the binding of splicing factors to short low-complexity regulatory sequences. The relationship between exonic splicing regulatory sequences and coding sequences is still poorly understood. We demonstrate that exons that are coregulated by any given splicing factor share a similar nucleotide composition bias and preferentially code for amino acids with similar physicochemical properties because of the nonrandomness of the genetic code. Indeed, amino acids sharing similar physicochemical properties correspond to codons that have the same nucleotide composition bias. In particular, we uncover that the TRA2A and TRA2B splicing factors that bind to adenine-rich motifs promote the inclusion of adenine-rich exons coding preferentially for hydrophilic amino acids that correspond to adenine-rich codons. SRSF2 that binds guanine/cytosine-rich motifs promotes the inclusion of GC-rich exons coding preferentially for small amino acids, whereas SRSF3 that binds cytosine-rich motifs promotes the inclusion of exons coding preferentially for uncharged amino acids, like serine and threonine that can be phosphorylated. Finally, coregulated exons encoding amino acids with similar physicochemical properties correspond to specific protein features. In conclusion, the regulation of an exon by a splicing factor that relies on the affinity of this factor for specific nucleotide(s) is tightly interconnected with the exon-encoded physicochemical properties. We therefore uncover an unanticipated bidirectional interplay between the splicing regulatory process and its biological functional outcome.

Exploiting Synergistic Effects in Organozinc Chemistry for Direct Stereoselective C-Glycosylation Reactions at Room Temperature

Pairing a range of bis(aryl) zinc reagents ZnAr₂ with the stronger Lewis acidic [(ZnAr^F₂ )] (Ar^F =C₆ F₅ ), enables highly stereoselective cross-coupling between glycosyl bromides and ZnAr₂ without the use of a transition metal. Reactions occur at room temperature with excellent levels of stereoselectivity, where ZnAr^F₂ acts as a non-coupling partner although its presence is crucial for the execution of the C(sp² )-C(sp³ ) bond formation process. Mechanistic studies have uncovered a unique synergistic partnership between the two zinc reagents, which circumvents the need for transition-metal catalysis or forcing reaction conditions. Key to the success of the coupling is the avoidance of solvents that act as Lewis bases versus diarylzinc compounds (e.g. THF).

Ferrier Rearrangement of 1,2-Dihydropyrans with Organozinc Species in Toluene/n-Dibutyl Ether

Herein, we report the catalyst-free addition of organozinc species to glycal derivatives and dihydropyrans in a toluene/n-dibutyl ether solvent mixture via a Ferrier rearrangement at room temperature. This methodology requires only a slight excess of the nucleophile and leads preferentially to the C-glycoside α-anomer. Various 1,2-dihydropyrans were assessed with a range of nucleophiles (aryl, alkynyl, alkyl) yielding the desired C-glycosides in good yield and diastereoselectivity up to 20:1.

Nucleosome eviction in mitosis assists condensin loading and chromosome condensation

Condensins associate with DNA and shape mitotic chromosomes. Condensins are enriched nearby highly expressed genes during mitosis, but how this binding is achieved and what features associated with transcription attract condensins remain unclear. Here, we report that condensin accumulates at or in the immediate vicinity of nucleosome-depleted regions during fission yeast mitosis. Two transcriptional coactivators, the Gcn5 histone acetyltransferase and the RSC chromatin-remodelling complex, bind to promoters adjoining condensin-binding sites and locally evict nucleosomes to facilitate condensin binding and allow efficient mitotic chromosome condensation. The function of Gcn5 is closely linked to condensin positioning, since neither the localization of topoisomerase II nor that of the cohesin loader Mis4 is altered in gcn5 mutant cells. We propose that nucleosomes act as a barrier for the initial binding of condensin and that nucleosome-depleted regions formed at highly expressed genes by transcriptional coactivators constitute access points into chromosomes where condensin binds free genomic DNA.

CT and MRI imaging at the acute phase of inaugural non-traumatic hepatic haemorrhages

PURPOSE

Although rare, non-traumatic hepatic haemorrhage is a known complication of liver tumors. In cases where the haemorrhage is the first clinical event, diagnostic work-up is critical.

MATERIAL AND METHODS

This retrospective study was conducted between July 2001 and March 2011. Acute phase CT-scan and MRI imaging in patients diagnosed with non-traumatic liver hematomas were interpreted with particular attention to the radio-semiotic characteristics of hematomas and liver lesions. Those findings were then confronted to the patients' final diagnoses.

RESULTS

Twelve patients were included (mean age of 42 years). In seven of them a suspect liver lesion was discovered in the acute CT-Scan or MRI imaging. All lesions were strongly hyper vascular.The haemorrhage revealed hepatocarcinoma in four patients, liver adenoma in two and focal nodular hyperplasia in an other.

CONCLUSION

It is important in spontaneous liver haemorrhage to consider the high probability of hepatocarcinoma or potentially malignant lesions even when the patient has no known hepatic disorders, and especially in young patients. The results of this study show that imaging is a key issue at the acute phase of inaugural non-traumatic hepatic haemorrhages and requires a simple but complete triphasic injected protocol.

Computed tomography of the parathyroids: the value of density measurements to distinguish between parathyroid adenomas of the lymph nodes and the thyroid parenchyma

PURPOSE

To compare the densities of parathyroid adenomas, lymph nodes and the thyroid parenchyma during multi-phase cervico-thoracic computed tomography to determine the differentiating threshold values.

MATERIALS AND METHODS

This study comprises 30 patients operated for a parathyroid adenoma after computed tomography without injection and then 45 and 70 seconds after the injection of an iodine based contrast product (350 mgI/mL, 150 mL, 3 mL/s). The density of the adenomas, lymph nodes and thyroid was measured during the three phases (D0, D45, D70). The relative enhancement (RE) at 45 seconds was calculated: RE=(D45-D0)/D0.

RESULTS

A significant difference was found in the spontaneous density of the parathyroid adenomas of the thyroid (P<0.01) with a threshold value of 75 HU. A significant difference is found in the enhancement after injection of the adenomas and lymph nodes (P<0.01). The adenomas present an enhancement peak at 45 seconds while the maximum enhancement of the lymph nodes is at 70 seconds. At 45 seconds, a threshold value of 114 HU and an RE 125% allows them to be distinguished (sensitivity and specificity 0.96).

CONCLUSION

Measurement of the densities can differentiate between the parathyroid adenomas, lymph nodes and thyroid.

Activities of antistaphylococcal antibiotics towards the extracellular and intraphagocytic forms of Staphylococcus aureus isolates from a patient with persistent bacteraemia and endocarditis

Decreased susceptibility of Staphylococcus aureus to antistaphylococcal agents may be associated with inability to eradicate intracellular forms, which could explain therapeutic failures. This hypothesis was tested using clinical isolates obtained from a patient with persistent staphylococcal bacteraemia under therapy. Four isogenic isolates (three from tissue, one from blood) with increased MICs for vancomycin (1-4 mg/L) and for daptomycin (1-4 mg/L) were collected after an initial 16-day treatment with vancomycin-rifampicin-gentamicin, followed by 13-20 days of treatment with daptomycin-rifampicin-gentamicin. Isolates were tested for MICs and for: (i) vancomycin (BODIPY-FL-vancomycin) and daptomycin binding; (ii) cell wall turnover (loss of N-acetyl-d-[1-(14)C]glucosamine in 30 min after 1 h of labelling); and (iii) Triton X-100-induced autolysis. Extracellular (broth) and intracellular (THP-1 macrophages) activities of rifampicin, linezolid and fusidic acid at C(max), and of vancomycin, daptomycin, quinupristin-dalfopristin and oritavancin over a wide range of extracellular concentrations (with pharmacological modelling to determine E(max)), were measured at 24 h. Increases in vancomycin MICs correlated with increased drug binding, and decreased cell wall turnover and detergent-induced autolysis. Increases in daptomycin MICs correlated with decreased daptomycin binding. Intracellular activity was weak (E(max) <1 log(10) CFU decrease) for vancomycin against all isolates, and for daptomycin against isolates with MICs >1 mg/L. Among all antibiotics tested, only quinupristin-dalfopristin and oritavancin provided close to bactericidal intracellular activities (1.6-2.5 log(10) CFU decreases at C(max)). Determination of the intracellular susceptibility of S. aureus, combined with improved methods of diagnosis, could be useful when dealing with persistent staphylococcal infections and could improve therapy.

Infiltration foraminale L5-S1 radioguidée dans le traitement de la lombosciatique S1

OBJECTIVE

To assess the efficacy of fluoroscopy guided L5-S1 transforaminal steroid injections for the treatment of S1 radiculopathy secondary to intervertebral disk disorder.

METHOD

41 patients were included: prospective study (20 patients) and retrospective study (21 patients). All patients suffered from S1 radiculopathy secondary to nerve root compression by intervertebral disk material, as demonstrated by lumbar spine CT. The patients underwent 2 fluoroscopy guided L5-S1 transforaminal injections of steroid (Hydrocotancyl 125 mg), at 8 days interval.

RESULTS

60% of patients showed significant improvement of their painful radiculopathy at day 8 (n:41), 60-67% at day 30 (n:41) and 67% at day 90 (n:18).

CONCLUSION

Fluoroscopy guided L5-S1 transforaminal injection showed good efficacy in the treatment of S1 radiculopathy.

Biochemical and histological responses in mussel (Mytilus edulis) exposed to North Sea oil and to a mixture of North Sea oil and alkylphenols

Several environmental chemicals are suspected to be responsible for adverse health effects on the reproductive system in various organisms. During this work, environmentally relevant concentrations of North Sea oil were used alone or in combination with alkylphenols and additional PAH to study the effect on vitellogenin-like protein expression and gonadal development in mussels. North Sea oil (0.5 ppm) induced the expression of phospho-proteins in both sexes indicating that some compounds are oestrogen-mimics. This induction was not seen in samples dosed with the mixture but signs of toxic effects were observed in the gonads. Indeed, numerous degenerating ovarian follicles in females and foci, similar to vertebrate melanomacrophage centres, were observed in testes.

Target-controlled infusion of propofol and remifentanil in cardiac anaesthesia: influence of age on predicted effect-site concentrations

BACKGROUND

Propofol-anaesthesia administrated via target-controlled infusion (TCI) has been proposed for cardiac surgery. Age-related changes in pharmacology explain why propofol dose requirement is reduced in elderly patients. However, the Marsh pharmacokinetic model incorporated in the Diprifusor propofol device does not take age into account as a covariable. In the absence of depth of anaesthesia monitoring, this limitation could cause adverse cardiovascular effects resulting from propofol overdose in older patients. We assessed the influence of age on effect-site propofol concentrations predicted by the Diprifusor and titrated to the bispectral index score (BIS) during cardiac anaesthesia.

METHODS

Forty-five patients received propofol by Diprifusor and remifentanil by software including Minto model. Propofol and remifentanil effect-site concentrations were adapted to BIS (40-60) and haemodynamic profile, respectively. The influence of age on effect-site concentrations was assessed by dividing patients into two groups: young (<65 yr) and elderly (> or =65 yr).

RESULTS

For a similar depth of anaesthesia, effect-site propofol concentrations were significantly lower in elderly patients at the different stages of cardiac surgery. The mean dose of propofol required to perform tracheal intubation was significantly lower in elderly patients. However, the overall doses of propofol were comparable in both groups. Neither effect-site remifentanil concentrations nor overall doses of remifentanil were significantly different between the two groups.

CONCLUSIONS

In cardiac anaesthesia, target concentrations of propofol must be reduced in elderly patients. Although this probably contributes to improving intraoperative haemodynamic stability, the absence of decrease in overall dose requirement of propofol suggests that this adjustment is relatively moderate.

Quality of life in multiple sclerosis: influence of interferon-beta1 a (Avonex) treatment

BACKGROUND

Numerous data argue for initiating treatment with interferon-beta (IFN-beta) at an early stage in multiple sderosis (MS). The consequences of its use may negatively influence the MS patient's quality of life (QoL).

OBJECTIVE

To evaluate the QoL of MS patients before and after a one-year period of treatment with IFN-beta1a (Avonex).

PATIENTS AND METHODS

QoL was assessed using the SF-36 in 121 relapsing-remitting MS patients. We compared QoL before and after treatment and with data from a normal population. We also studied the possible influence of disease progression on the SF-36 scores.

RESULTS

One hundred six patients completed the study (87%). Compared to a normal population, patients were, at baseline, worse off for all QoL scales, varying from a minimum decrease of 0.73 SD in mental health, to a maximum decrease of 1.55 SD in general health. After treatment, we found no significant changes in any of the QoL scores, except for physical function, where we noted a slight but significant decrease (p = 0.03). Furthermore, there was no significant change either in the physical component summary (PCS) or mental component summary (MCS). The 'reported health transition' item was significantly improved compared to baseline (p = 0.001). At indusion, significant correlations were found between EDSS scores and scores of physical function (p < 0.001), role - physical (p < 0.01), general health and social function (both p < 0.01), and with the PCS (p < 0.01). Patients with dinical relapses and/or disability progression had a more significant decease in physical function (p < 0.05) and also in social function (p < 0.05).

CONCLUSION

The QoL, assessed by the SF-36 scale, is correlated with disability in MS. IFN-beta1a treatment (Avonex) has no negative effect on MS patient's QoL.

Early evaluation of dressage ability in different breeds

Dressage is one of the Olympic equestrian sports practiced in several countries using different horse breeds. Specific characteristics of the walk, trot and canter are required for dressage. It has been assumed that some of these traits could be selected for genetically and contribute to dressage performance. The purpose of this study was to compare the walk, trot and conformation characteristics in young horses of different breeds used for dressage. A total of 142 horses age 3 years were classified into 3 groups of breeds (German, French and Spanish saddle horses) and tested using the same procedure. The skeletal conformation measurements were made by image analysis. Gait variables of the walk and trot were measured by the accelerometric gait analysis system Equimetrix. Discriminant analysis could explain the variability between the groups by taking into account the walk (P<0.0003), trot (P<0.0001) and conformation variables (P<0.0001). Many gait and conformation variables were significantly different between the breeds. In summary, the German horses had gait characteristics more adapted for dressage competition, and the results of this group could be used as a reference for early evaluation in dressage. Purebred Spanish horses could be considered as a reference for collected gaits used for farm work and old academic dressage. The gait and conformation tests could be applied in a breeding or crossing plan to detect more accurately young horses with good dressage ability.

The effect of reins on kinetic variables of locomotion

The equestrian literature and reports of experienced riders indicated that attitude of a horse's head and neck is related to the equine locomotion characteristics. The purpose of this study was to quantify the effects of 3 types of reins on locomotion at walk and trot. Eight saddle horses were tested in an automatic walker without reins, with rubber bands, Chambons and Back lift, using the same procedure. The rubber bands closed the head-neck angle, whereas the Chambons and the Back lift opened it. The gait characteristics were measured with the Equimetrix gait analysis system. Two accelerometric devices were fixed on the sternum and sacrum to measure the kinetic characteristics of the fore- and hindlimbs at walk and trot. Analysis of variance was used to test the effects of reins on the fore- and hindlimbs. All 3 types of reins significantly (P<0.05) modified walk and trot, with increased forelimb propulsion at the trot (P<0.05). Chambons increased the dorsoventral activity of the hindlimbs at the trot and hindlimb propulsion at the walk (P<0.05). Back lift increased forelimb dorsoventral activity both at the trot and walk (P<0.05). It was concluded that the Chambons increased the activity of the hindlimbs while Back lift increased that of the forelimbs. The use of reins modified the head placement and the fore- and hindlimbs activity. The specific effect of each type of rein can be used for training, rehabilitation or management of locomotor's injury.