Oxygen supply controls the onset of pristinamycins production by Streptomyces pristinaespiralis in shaking flasks

Antibiotics are secondary metabolites, generally produced during stationary phase of growth under different nutritional and hydrodynamic stresses. However, the exact mechanisms of the induction of antibiotics production are still not clearly established. In a previous study, the induction of pristinamycins production by Streptomyces pristinaespiralis as well as product concentrations were correlated with power dissipation per unit of volume (P/V) in shaking flasks. In this study, detailed kinetics of growth, substrate consumption, oxygen transfer rate and pristinamycins production under varying P/V conditions have been obtained and analyzed. Our results showed that higher P/V resulted in a higher concentration of biomass and promoted an earlier nutrient limitation and ultimately an earlier induction of pristinamycins production. The maximal specific growth rate, specific oxygen consumption rate and specific consumption rate of glutamate increased with P/V while influence was less marked with specific consumption rate of glucose, arginine, ammonium ions and phosphate. When oxygen uptake rate (OUR) was limited by free-surface oxygen transfer, pristinamycins production was not detected despite the occurrence of nitrogen and/or phosphate sources limitation. The threshold value for OUR observed was around 25 mmol L(-1) h(-1). This suggested that a limitation in nitrogen and/or phosphate alone was not sufficient to induce pristinamycins production by S. pristinaespiralis pr11. To induce this production, the oxygen transfer had to be non-limiting.

Predictors of institution admission in the year following acute hospitalisation of elderly people

OBJECTIVES

The aim of the study was to identify factors related to institutionalisation within one-year follow up of subjects aged 75 or over, hospitalised via the emergency department (ED).

DESIGN

Prospective multicentre cohort.

SETTING

Nine French university teaching hospitals.

PARTICIPANTS

One thousand and forty seven (1 047) non institutionalised subjects aged 75 or over, hospitalised via ED. A sub-group analysis was performed on the 894 subjects with a caregiver.

MEASUREMENTS

Patients were assessed using Comprehensive Geriatric Assessment (CGA) tools. Cox survival analysis was performed to identify predictors of institutionalisation at one year.

RESULTS

Within one year after hospital admission, 210 (20.1%) subjects were institutionalised. For the overall study population, age >85 years (HR 1.6; 95%CI 1.1-2.1; p=0.005), inability to use the toilet (HR 1.6; 95%CI 1.1-2.4; p=0.007), balance disorders (HR 1.6; 95%CI 1.1-2.1; p=0.005) and presence of dementia syndrome (HR 1.9; 95%CI 1.4-2.6; p<0.001) proved to be independent predictors of institutionalisation; while a greater number of children was inversely linked to institutionalisation (HR 0.8; 95%CI 0.7-0.9; p<0.001). Bathing was of borderline significance (p=.09). For subjects with a caregiver, initial caregiver burden was significantly linked to institutionalisation within one year, in addition to the predictors observed in the overall study population.

CONCLUSIONS

CGA performed at the beginning of hospitalisation in acute medical wards is useful to predict institutionalisation. Most of the predictors identified can lead to targeted therapeutic options with a view to preventing or delaying institution admission.

Real-time terahertz near-field microscope

We report a terahertz near-field microscope with a high dynamic range that can capture images of a 370 x 740 μm2 area at 35 frames per second. We achieve high spatial resolution (14 μm corresponding to λ/30 for a center frequency at 0.7 THz) on a large area by combining two novel techniques: terahertz generation by tilted-pulse-front excitation and electro-optic balanced imaging detection using a thin crystal. To demonstrate the microscope capability, we reveal the field enhancement at the gap position of a dipole antenna after the irradiation of a terahertz pulse.

Effect of surfactants, dispersion and temperature on solubility and biodegradation of phenanthrene in aqueous media

In the present study surfactant addition with the help of either a mechanical dispersion or a thermal treatment was applied in order to increase the solubility and the bioavailability of phenanthrene in aqueous media, and therefore to promote its biodegradation. Among four tested surfactants (Tween 80, Brij 30, sodium dodecyl sulphate and rhamnolipids), Brij 30 (0.5 gL(-1)) showed the best results allowing us to attain about 20 mgL(-1) of soluble phenanthrene. An additional thermal treatment at 60°C for 24h, 200 rpm permitted to increase the solubility of phenanthrene in the presence of Brij 30 (0.5 gL(-1)) to about 30 mgL(-1). Higher dispersions of phenanthrene particles as well as the reduction of their size were obtained using Ultra-Turrax and French press. The biodegradation of phenanthrene by Pseudomonas putida was then investigated. The reduction of size of phenanthrene particles by mechanical dispersion did not influence its biodegradation, suggesting that P. putida consumed only soluble phenanthrene. The addition of Brij 30 (0.5 gL(-1)) permitted to obtain more phenanthrene metabolized. The use of Brij 30 coupled with a transitory heating of phenanthrene-containing medium at 60°C led to an even more complete biodegradation. This might be a promising way to enhance biodegradation of PAHs.

Therapeutic approach of primary bone tumours by bisphosphonates

Bone tumours can be dissociated in two main categories: i) primary bone tumours (benign or malignant) including mainly osteosarcoma and other sarcomas.ii)and giant cell tumour and bone metastases originate from others cancer (Breast, prostate, kidney cancer, etc). These tumours are able to destroy or/and induce a new calcified matrix. However, the first step of bone tumour development is associated with an induction of bone resorption and the establishment of a vicious cycle between the osteoclasts and the tumour growth. Indeed, bone resorption contributes to the pathogenesis of bone tumour by the release of cytokines (IL6, TNFα) which govern the bone tumour's development and which are trapped into the bone matrix. Bisphosphonates (BPs) are chemical compounds of P-C-P structure with a high affinity for bone hydroxyapatite crystals. Thus, they have been used as a carrier for radio nucleotides to develop novel approaches of bone imaging. BPs exert also indirect anti-tumour activities in vivo. Indeed, BPs directly interfere with the bone microenvironment and target osteoclasts, endothelial cells and immune cells (tumour-associated macrophages, γ9δ2 T cells). BPs induce tumour cell death in vitro and same activity is suspected in vivo. The present review summarizes the mechanisms of actions of BPs as well as their clinical interests in bone primary tumours.

TP53 mutations in irinotecan-refractory KRAS wt-BRAF wt metastatic colorectal cancer patients treated with cetuximab-based chemotherapy

426

Background: Anti-EGFR antibodies are more efficient when EGFR pathway is activated without mutations on downstream effectors such as KRAS and BRAF (Lievre et al. Cancer Res. 2008 and Khambata-Ford et al. J Clin Oncol. 2007). Moreover, tumor growth from EGFR activation may required inactivation of the molecular brake p53 suggesting that anti-EGFR therapy should be more efficient if p53 is inactivated (Oden-Gangloff et al. Br J Cancer. 2008). The aim of the study was to evaluate, in an independent series, the impact of p53 mutations in irinotecan-refractory KRAS wt-BRAF wt MCRC patients treated with anti- EGFR.

Methods: A total of 100 MCRC patients treated with cetuximab-based CT were included. KRAS and BRAF mutational status were determined using SNaPshot or allelic discrimination methods. TP53 mutations within exons 5 to 8 were detected using direct sequencing. Response to cetuximab, based on RECIST criteria, was evaluated according to molecular analysis using the Fischer exact test. Progression- free survivals (PFS) and overall survival (OS) were calculated using the Kaplan-Meier method and compared with log-rank test.

Results: Objective response (OR = partial and complete response) was observed in 40% and control disease (CD = OR+stable disease) in 74% of patients. Median PFS and OS was 12 weeks and 12 months, respectively. TP53 mutations were detected in 66% of patients and were not significantly associated with OR and CD. In contrast, patients with KRAS wt-BRAF wt and TP53 mutation had significantly longer PFS as compared to KRAS wt–BRAF wt and TP53 non mutated patients (32 weeks vs. 21 weeks, respectively; p = 0.01). There was a trend but not significant increased OS in patients with TP53 mutations (16 months vs. 13 months)

Conclusions: In this independent study, our results confirm that TP53 mutation was significantly associated with an increase PFS in irinotecan-refrcatory KRAS wt-BRAF wt MCRC patients treated with anti-EGFR.

[Table: see text]

Is the screening test of the French version of the dementia quality of life questionnaire indispensable?

The aim of this study was to evaluate the usefulness of the screening questions in the French version of the Dementia Quality of Life (DQoL) questionnaire. To assess the psychometric properties of the French DQoL, 155 patients with mild-to-moderate dementia were recruited. Here, we compared the psychometric properties of the instrument between patients who passed the screening test (n = 109) and the whole study population (n = 155). The French DQoL version showed a good test-retest reliability at a 2-week interval (0.95 ≤ intraclass correlation coefficients ≤ 1.0), and an average internal consistency (0.58 ≤ Cronbach's α ≤ 0.87) for the 2 study groups. Significant differences were observed in the 2 groups for 4 dimensions of the DQoL regarding dementia severity (Cornell scale), and for 3 dimensions evaluating depression (MMSE). Convergent validity with the Duke Health Profile revealed many significant correlations between dimensions not only in the 109 patients, but also in the whole study population. Our study demonstrated that patients who failed the screening procedure nonetheless seemed to be able to answer the DQoL questionnaire, the whole study group showing acceptable psychometric properties.

Near-field THz imaging of free induction decay from a tyrosine crystal

We demonstrate images of free induction decay (FID) signals from a grain of tyrosine in the near-field of the THz frequency region. By combining electro-optic sampling with a charge-coupled-device (CCD) camera, our near-field THz microscope allows us to visualize the electric field blinking with the FID signal with spatial resolution of better than 70 microm. The oscillating frequency of the FID signal centered at approximately 1 THz corresponds to the vibrational mode of the tyrosine crystal. These results confirm that the THz near-field microscope can take spectroscopic images with subwavelength spatial resolution (approximately lambda/4).

Early markers of prolonged hospital stay in demented inpatients: a multicentre and prospective study

BACKGROUND

Dementia is a serious, chronic, and costly public health problem. Prior studies have described dementia as increasing length of hospital stay, but so far no explanations have been proposed.

METHODS

To identify early markers for prolonged hospital stay in demented elderly inpatients, 178 community-dwelling or institutionalized subjects aged 75+, hospitalized through an emergency department in 9 teaching hospitals in France, were analyzed. Prolonged hospital stays were defined according a limit adjusted for Diagnosis Related Group. All patients underwent a comprehensive geriatric assessment at admission. Logistic regression multifactorial mixed model was performed. Center effect was considered as a random effect.

RESULTS

Of the 178 stays, 52 were prolonged. Most concerned community-dwelling patients (86%). Multifactor analysis demonstrated that demographic variables had no influence on the length of stay, while diagnosis of delirium (OR 2.31; 95% CI 1.77 - 2.91), walking difficulties (OR 1.94; 95% CI 1.62 - 2.43) and report by the informal caregiver of moderate or severe burden (OR 1.52; 95% CI 1.19 - 1.86) or low social quality-of-life score (OR 1.25; 95% CI 1.03 - 1.40), according to the Zarit's Burden Inventory short scale (12 items) and the Duke's Health Profile respectively, were identified as early markers for prolonged hospital stays.

CONCLUSION

At the time of the rising incidence of cognitive disorders, these results suggest that preventive approaches might be possible. In a hospital setting as well as in a community-dwelling population, more specific, specialized and coordinated care, using the expertise of multiple disciplines appears as a probable effective measure to limit prolonged hospital stay. Such approaches require (i) clear patient-oriented goal definition, (ii) understanding and appreciation of roles among various health care and social disciplines and, (iii) cooperation between partners in patient's management. However, the cost- and health-effectiveness of such approaches should be evaluated.

Terahertz pulse induced intervalley scattering in photoexcited GaAs

Nonlinear transient absorption bleaching of intense few-cycle terahertz (THz) pulses is observed in photoexcited GaAs using opticalpump--THz-probe techniques. A simple model of the electron transport dynamics shows that the observed nonlinear response is due to THz-electric- field-induced intervalley scattering over sub-picosecond time scales as well as an increase in the intravalley scattering rate attributed to carrier heating. Furthermore, the nonlinear nature of the THz pulse transmission at high peak fields leads to a measured terahertz conductivity in the photoexcited GaAs that deviates significantly from the Drude behavior observed at low THz fields, emphasizing the need to explore nonlinear THz pulse interactions with materials in the time domain.

Mild Alzheimer's disease: a "position paper"

Under the auspices of the Societe Francaise de Geriatrie et Gerontologie, a multi-disciplinary group of specialists in geriatrics, neurology, epidemiology, psychiatry, neuroradiology and nuclear medicine met with the aim of drawing up references on the methods for diagnosing and treating mild Alzheimer's disease. The critical analysis of international literature, conducted by Professor Bruno Vellas for the scientific committee, has served to support study of the latest knowledge in 2008. The multi-disciplinary group met on 14 and 15 May 2008 in order to set out the questions that this study must answer and to allocate draft studies. Thus, it has been possible to conduct a study focused on mild Alzheimer's disease, giving particular attention to diagnostic procedure, specific methods of treatment and the benefits of making a diagnosis.

Improved terahertz two-color plasma sources pumped by high intensity laser beam

We investigate the intensity dependent spatial drift of two-color plasma based terahertz (THz) sources. A simple scheme that uses an off-axis parabolic mirror is presented to overcome this shifting. In addition, the THz energy and electric field measurements are related via the real time images of the THz spot size.

Predicting early mortality among elderly patients hospitalised in medical wards via emergency department: the SAFES cohort study

OBJECTIVES

The aim of the study was, by early identification of deleterious prognostic factors that are open to remediation, to be in a position to assign elderly patients to different mortality risk groups to improve management.

DESIGN

Prospective multicentre cohort.

SETTING

Nine French teaching hospitals.

PARTICIPANTS

One thousand three hundred and six (1 306) patients aged 75 and over, hospitalised after having passed through Emergency Department (ED).

MEASUREMENTS

Patients were assessed using Comprehensive Geriatric Assessment (CGA) tools. A Cox survival analysis was performed to identify prognostic variables for six-week mortality. Receiver Operating Characteristics analysis was used to study the discriminant power of the model. A mortality risk score is proposed to define three risk groups for six-week mortality.

RESULTS

Crude mortality rate after a six week follow-up was 10.6% (n=135). Prognostic factors identified were: malnutrition risk (HR=2.1; 95% CI: 1.1-3.8; p=.02), delirium (HR=1.7; 95% CI: 1.2-2.5; p=.006), and dependency: moderate dependency (HR=4.9; 95% CI: 1.5-16.5; p=.01) or severe dependency (HR=10.3; 95% CI: 3.2-33.1; p < .001). The discriminant power of the model was good: the c-statistic representing the area under the curve was 0.71 (95% IC: 0.67 - 0.75; p < .001). The six-week mortality rate increased significantly (p < .001) across the three risk groups: 1.1% (n=269; 95% CI=0.5-1.7) in the lowest risk group, 11.1% (n=854; 95% CI=9.4-12.9) in the intermediate risk group, and 22.4% (n=125; 95% CI=20.1-24.7) in the highest risk group.

CONCLUSIONS

A simple score has been calculated (using only three variables from the CGA) and a practical schedule proposed to characterise patients according to the degree of mortality risk. Each of these three variables (malnutrition risk, delirium, and dependency) identified as independent prognostic factors can lead to a targeted therapeutic option to prevent early mortality.

Farnesyl diphosphate synthase is involved in the resistance to zoledronic acid of osteosarcoma cells

We recently demonstrated original anti-tumor effects of zoledronic acid (Zol) on osteosarcoma cell lines independently of their p53 and Rb status. The present study investigated the potential Zol-resistance acquired by osteosarcoma cells after prolonged treatment. After 12 weeks of culture in the presence of 1 μm Zol, the effects of high doses of Zol (10–100 μm) were compared between the untreated rat (OSRGA, ROS) and human (MG63, SAOS2) osteosarcoma cells and Zol-pretreated cells in terms of cell proliferation, cell cycle analysis, migration assay and cytoskeleton organization. Long-term treatment with 1 μm Zol reduced the sensitivity of osteosarcoma cells to high concentrations of Zol. Furthermore, the Zol-resistant cells were sensitive to conventional anti-cancer agents demonstrating that this resistance process is independent of the multidrug resistance phenotype. However, as similar experiments performed in the presence of clodronate and pamidronate evidenced that this drug resistance was restricted to the nitrogen-containing bisphosphonates, we then hypothesized that this resistance could be associated with a differential expression of farnesyl diphos-phate synthase (FPPS) also observed in human osteosarcoma samples. The transfection of Zol-resistant cells with FPPS siRNA strongly increased their sensitivity to Zol. This study demonstrates for the first time the induction of metabolic resistance after prolonged Zol treatment of osteosarcoma cells confirming the therapeutic potential of Zol for the treatment of bone malignant pathologies, but points out the importance of the treatment regimen may be important in terms of duration and dose to avoid the development of drug metabolic resistance.

Influence of intracellular nucleotide and nucleotide sugar contents on recombinant interferon-gamma glycosylation during batch and fed-batch cultures of CHO cells

Both the macroheterogeneity of recombinant human IFN-gamma produced by CHO cells and intracellular levels of nucleotides and sugar nucleotides, have been characterized during batch and fed-batch cultures carried out in different media. Whereas PF-BDM medium was capable to maintain a high percentage of the doubly- glycosylated glycoforms all over the process, mono-glycosylated and non-glycosylated forms increased during the batch culture using SF-RPMI medium. Intracellular level of UTP was higher in PF-BDM all over the batch culture compared to the SF-RPMI process. UDP-Gal accumulated only during the culture performed in PF-BDM medium, probably as a consequence of the reduced UDP-Glc synthesis flux in SF-RPMI medium. When the recombinant CHO cells were cultivated in fed-batch mode, the UTP level remained at a relatively high value in serum-containing RPMI and its titer increased during the fed-phase indicating an excess of biosynthesis. Besides, an accumulation of UDP-Gal occurred as well. Those results all together indicate that UTP and UDP-Glc syntheses in CHO cells cultivated in SF-RPMI medium in batch process, could be limiting during the glycosylation processes of the recombinant IFN-gamma. At last, the determination of the energetic status of the cells over the three studied processes suggested that a relationship between the adenylate energy charge and the glycosylation macroheterogeneity of the recombinant IFN-gamma may exist.

What is there left to learn about the Drosophila clock?

Circadian rhythms offer probably the best understanding of how genes control behavior, and much of this understanding has come from studies in Drosophila. More recently, genetic manipulation of clock neurons in Drosophila has helped identify how daily patterns of activity are programmed by different clock neuron groups. Here, we review some of the more recent findings on the fly molecular clock and ask what more the fly model can offer to circadian biologists.

Generation of 1.5 microJ single-cycle terahertz pulses by optical rectification from a large aperture ZnTe crystal

We demonstrate the generation muJ-level, single-cycle terahertz pulses by optical rectification from a large-aperture ZnTe single crystal wafer. Energies up to 1.5 muJ per pulse and a spectral range extending to 3 THz were obtained using a 100 Hz Ti:sapphire laser source and a 75-mmdiameter, 0.5-mm-thick, (110) ZnTe crystal, corresponding to an average power of 150 muW and an energy conversion efficiency of 3.1 x 10(-5). We also demonstrate real-time imaging of the focused terahertz beam using a pyroelectric infrared camera.