Effect of oxygen on the biosynthesis of flavor compound 3-methylbutanal from leucine catabolism during batch culture in Carnobacterium maltaromaticum LMA 28.

In this study, we demonstrated the effect of different dissolved oxygen concentrations (DOC) on cell growth and intracellular biosynthesis of 3-methylbutanal from leucine catabolism in Carnobacterium maltaromaticum LMA 28 during batch culture. The maximum specific growth rate was obtained in culture when DOC was controlled at 50% of air saturation. The specific consumption rates of glucose and specific production rates of lactate were higher at a DOC at 50 or 90% of air saturation. Carnobacterium maltaromaticum LMA 28 produced high quantities of 3-methylbutanal and 3-methylbutanol during culture with DOC maintained at 90%, suggesting that oxygen had a significant effect of the formation of these flavor compounds. This high formation of flavor compounds in an oxygen-rich environment was attributed to the simultaneous activation and stimulation of both α-ketoacid decarboxylase (KADC) and α-ketoacid dehydrogenase (KADH) pathways. Thus, intracellular biosynthesis of 3-methylbutanal can be controlled by modifying the DOC of the culture or food product during fermentation.

Effects of bioreactor hydrodynamics on the physiology of Streptomyces.

Streptomyces are filamentous bacteria which are widely used industrially for the production of therapeutic biomolecules, especially antibiotics. Bioreactor operating conditions may impact the physiological response of Streptomyces especially agitation and aeration as they influence hydromechanical stress, oxygen and nutrient transfer. The understanding of the coupling between physiological response and bioreactor hydrodynamics lies on a simultaneous description of the flow and transfers encountered by the bacteria and of the microbial response in terms of growth, consumption, morphology, production or intracellular signals. This article reviews the experimental and numerical works dedicated to the study of the coupling between bioreactor hydrodynamics and antibiotics producing Streptomyces. In a first part, the description of hydrodynamics used in these works is presented and then the main relations used. In a second part, the assumptions made in these works are discussed and put into emphasize. Lastly, the various Streptomyces physiological responses observed are detailed and compared.

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.

[Indications for fluorescein angiography and optical coherence tomography angiography (OCTA) in medical retina: Changes from 2015 and 2018]. / Indications d'angiographie à la fluorescéine et d'OCT-angiographie en consultation de rétine médicale : comparaison entre 2015 et 2018.

INTRODUCTION: Non-invasive multimodal imaging, including optical coherence tomography angiography (OCTA), has demonstrated high sensitivity and specificity for the management of retinal diseases. Since the availability of OCTA in 2015, we have developed a policy of "as little fluorescein angiography as possible". In this study, we describe the rate of OCTA and fluorescein angiography (FA) performed and their indications. METHODS: Retrospective descriptive single-centre study. Chart review of patients examined for retinal disorders by one medical retina specialist between January 2015 and June 2018. RESULTS: 3487 patients were examined for a retinal disease. The charts of 651 of these patients (1170 eyes) were randomly selected for analysis (study group). The mean age in the study group was 72 years (60% female). Overall, OCTA and FA were performed in 49.4% and 6.5% of the studied eyes respectively. After the first year, the rate of FA decreased to 2%. The main indications for OCTA were age-related macular degeneration (AMD): 50%, central serous chorioretinopathy (CSC): 12% and retinal vascular occlusion: 10%. The most frequent indications for FA were AMD: 49%, diabetic retinopathy (DR): 18% and CSC: 14%. FA was performed in 16%, 11% and 10% of eyes diagnosed with DR, CSC and AMD respectively (P<0.05). CONCLUSION: In routine practice, OCTA was performed in half of the eyes examined for a retinal disorder. The overall rate of FA was 6.5% and dropped to 2% after the first year of OCTA use. DR was the main disorder still requiring FA.

International practices in the dietary management of fructose 1-6 biphosphatase deficiency.

BACKGROUND: In fructose 1,6 bisphosphatase (FBPase) deficiency, management aims to prevent hypoglycaemia and lactic acidosis by avoiding prolonged fasting, particularly during febrile illness. Although the need for an emergency regimen to avoid metabolic decompensation is well established at times of illness, there is uncertainty about the need for other dietary management strategies such as sucrose or fructose restriction. We assessed international differences in the dietary management of FBPase deficiency. METHODS: A cross-sectional questionnaire (13 questions) was emailed to all members of the Society for the Study of Inborn Errors of Metabolism (SSIEM) and a wide database of inherited metabolic disorder dietitians. RESULTS: Thirty-six centres reported the dietary prescriptions of 126 patients with FBPase deficiency. Patients' age at questionnaire completion was: 1-10y, 46% (n = 58), 11-16y, 21% (n = 27), and >16y, 33% (n = 41). Diagnostic age was: <1y, 36% (n = 46); 1-10y, 59% (n = 74); 11-16y, 3% (n = 4); and >16y, 2% (n = 2). Seventy-five per cent of centres advocated dietary restrictions. This included restriction of: high sucrose foods only (n = 7 centres, 19%); fruit and sugary foods (n = 4, 11%); fruit, vegetables and sugary foods (n = 13, 36%). Twenty-five per cent of centres (n = 9), advised no dietary restrictions when patients were well. A higher percentage of patients aged >16y rather than ≤16y were prescribed dietary restrictions: patients aged 1-10y, 67% (n = 39/58), 11-16y, 63% (n = 17/27) and >16y, 85% (n = 35/41). Patients classified as having a normal fasting tolerance increased with age from 30% in 1-10y, to 36% in 11-16y, and 58% in >16y, but it was unclear if fasting tolerance was biochemically proven. Twenty centres (56%) routinely prescribed uncooked cornstarch (UCCS) to limit overnight fasting in 47 patients regardless of their actual fasting tolerance (37%). All centres advocated an emergency regimen mainly based on glucose polymer for illness management. CONCLUSIONS: Although all patients were prescribed an emergency regimen for illness, use of sucrose and fructose restricted diets with UCCS supplementation varied widely. Restrictions did not relax with age. International guidelines are necessary to help direct future dietary management of FBPase deficiency.

A method for the determination of pyruvate carboxylase activity during the glutamic acid fermentation with Corynebacterium glutamicum.

A discontinuous lactate dehydrogenase coupled assay is described for the evaluation of the pyruvate carboxylase activity (Pc, EC 6.4.1.1) in a glutamate overproducing strain of Corynebacterium glutamicum. After an initial permeabilisation period of the cells, the method consisted of the fluorometric determination of the remaining pyruvate level after transformation into oxaloacetate by the endogenous Pc. The assay was demonstrated to be powerful and enabled the determination of the C. glutamicum Pc activity grown on different carbon sources. Besides, this method was used to assay Pc activity in C. glutamicum 2262 during a temperature triggered glutamate producing process with biotin excess or limitation.

Solubilization of phenanthrene above cloud point of Brij 30: a new application in biodegradation.

In the present study a new application of solubilization of phenanthrene above cloud point of Brij 30 in biodegradation was developed. It was shown that a temporal solubilization of phenanthrene above cloud point of Brij 30 (5wt%) permitted to obtain a stable increase of the solubility of phenanthrene even when the temperature was decreased to culture conditions of used microorganism Pseudomonas putida (28°C). A higher initial concentration of soluble phenanthrene was obtained after the cloud point treatment: 200 against 120µM without treatment. All soluble phenanthrene was metabolized and a higher final concentration of its major metabolite - 1-hydroxy-2-naphthoic acid - (160 against 85µM) was measured in the culture medium in the case of a preliminary cloud point treatment. Therefore a temporary solubilization at cloud point might have a perspective application in the enhancement of biodegradation of polycyclic aromatic hydrocarbons.

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.

Phosphoinositides are involved in control of the glucose-dependent growth resumption that follows the transition phase in Streptomyces lividans.

The interruption of the sblA gene of Streptomyces lividans was previously shown to lead to relief of glucose repression of the normally strongly glucose-repressed alpha-amylase gene. In addition to this relief, an early entry into stationary phase was observed when cells were grown in a minimal medium containing glucose as the main carbon source. In this study, we established that this mutant does not resume growth after the transition phase when cultured in the complex glucose-rich liquid medium R2YE and sporulates much earlier than the wild-type strain when plated on solid R2YE. These phenotypic differences, which were abolished when glucose was omitted from the R2YE medium, correlated with a reduced glucose uptake ability of the sblA mutant strain. sblA was shown to encode a bifunctional enzyme possessing phospholipase C-like and phosphoinositide phosphatase activities. The cleavage of phosphoinositides by SblA seems necessary to trigger the glucose-dependent renewed growth that follows the transition phase. The transient expression of sblA that takes place just before the transition phase is consistent with a regulatory role for this gene during the late stages of growth. The tight temporal control of sblA expression was shown to depend on two operator sites. One, located just upstream of the -35 promoter region, likely constitutes a repressor binding site. The other, located 170 bp downstream of the GTG sblA translational start codon, may be involved in the regulation of the degradation of the sblA transcript. This study suggests that phosphoinositides constitute important regulatory molecules in Streptomyces, as they do in eukaryotes.

Flexibility of the metabolism of Corynebacterium glutamicum 2262, a glutamic acid-producing bacterium, in response to temperature upshocks.

In order to test the temperature sensitivity of glutamate production metabolism, several temperature shifts, from 33 to 37, 38, 39, 40 or 41 degrees C, were applied to the temperature-sensitive strain, Corynebacterium glutamicum 2262, cultivated in a 24-h fed-batch process. Whereas glucose was entirely dedicated to biomass synthesis when cells were grown at 33 degrees C, applying temperature upshocks, whatever their range, triggered a redistribution of the carbon utilisation between glutamate, biomass and lactate production. Although increasing the culture temperature from 33 to 37, 38, 39 or 40 degrees C resulted in final glutamate titers superior to 80 g/l, temperatures resulting in the best chanelling of the carbon flow towards glutamic acid synthesis were 39 and 40 degrees C. Moreover, this study showed that the higher the temperature, the slower the growth rate and the higher the lactate accumulation.

Radiographic measurements of dysplastic adult hips.

Hip dysplasia is a not uncommon feature in adults and can vary from subtle acetabular dysplasia to complex sequelae of developmental dysplasia of the hip. This review article describes the most useful radiographic measurements used to evaluate the adult hip. The frontal projection of the pelvis permits measurement of the center-edge angle (CE angle) and "horizontal toit externe" angle (HTE angle), both of which assess the superior coverage of the acetabulum. The femoral neck-shaft angle (NSA) is also measured on this view. The false profile radiograph of the pelvis is described. It allows measurement of the vertical-center-anterior angle (VCA angle), which determines the anterior acetabular coverage and detects early degenerative hip joint disease. When surgery is contemplated, computed tomography (CT) is useful to better determine the anterior acetabular coverage by use of the anterior acetabular sector angle (AASA), and the posterior acetabular coverage by use of the posterior acetabular sector angle (PASA). CT also permits measurement of femoral anteversion. These measurements are particularly useful in the evaluation of acetabular dysplasia and for the preoperative assessment of the dysplastic hip.

Folding of the rabbit hemorrhagic disease virus capsid protein and delineation of N-terminal domains dispensable for assembly.

Rabbit hemorrhagic disease virus (RHDV) and European brown hare syndrome virus (EBHSV) are caliciviruses that produce severe symptoms and are lethal to rabbits and hares. The folding of the capsid protein was studied by determination of the antigenic pattern of chimeric capsid proteins, composed of regions from RHDV and EBHSV capsid proteins. The anti-RHDV monoclonal antibody (MAb) E3, which is known to bind an external conformational epitope, recognized the RHDV C-terminal region. The anti-RHDV MAb A47, which binds a buried epitope, recognized the RHDV N-terminal region. Using a pGEX expression library, we more precisely mapped the MAb A47 epitope on a 31 residues length peptide, between residue 129 and 160 of the VP60, confirming its location in the N-terminal part of the protein. These results demonstrate that the C-terminal part of the protein is accessible to the exterior whereas the N-terminal domain of the protein constitutes the internal shell domain of the particle. With the aim of using virus-like particles (VLPs) of RHDV as epitope carriers or DNA transfer vectors, we produced in the baculovirus system three proteins, DeltaN1, DeltaN2 and DeltaN3, truncated at the N terminus. The DeltaN1 protein assembled into VLPs, demonstrating that the first 42 amino acid residues are not essential for capsid assembly. In contrast, DeltaN2, from which the first 75 residues were missing, was unable to form VLPs. The small particles obtained with the DeltaN3 protein lacking residues 31 to 93, located in the immunodominant region of the RHDV capsid protein, indicate that up to 62 amino acid residues can be eliminated without preventing assembly.

Importance of phosphoenolpyruvate carboxylase of Corynebacterium glutamicum during the temperature triggered glutamic acid fermentation.

To give clues about the respective importance of phosphoenol-pyruvate carboxylase (PEPc) and pyruvate carboxylase (Pc) in Corynebacterium glutamicum metabolism during a temperature triggered glutamic acid fermentation, PEPc activity was genetically amplified and Pc activity was suppressed by biotin limitation in the culture medium. In absence of Pc activity, glutamate production was dramatically reduced whereas lactate excretion was strongly increased. Whereas PEPc amplification in excess of biotin (4 mg/L) only slightly modified the cell kinetics, under biotin limiting conditions this amplification strongly improved the glutamate production (4 microg/L). When Pc was absent, PEPc activity was sufficient to allow up to 70% of the maximal glutamate production rate and seemed to have an important anaplerotic role, especially at the beginning of the production phase. In contrast, Pc was predominant during the remainder of the glutamate fermentation.

[Liver transplantation, vascular complications, role of imaging, percutaneous therapeutic possibilities]. / Transplantation hépatique complications vasculaires place de l'imagerie possibilités thérapeutiques per-cutanées.

Duplex Doppler ultrasound should be the first investigation when a vascular complication is suspected. Serial examinations may increase sensitivity. Color imaging enhances identification of small vessels and increases specificity. Angiography is not necessary unless an pseudoaneurysm is suspected. When duplex Doppler ultrasound is abnormal, angiography is performed to evaluate the possibility of treatment. Endovascular therapeutic procedures appear to have a limited field of application in comparison to percutaneous biliary procedures. Hemostatic embolization or dilatation of vascular strictures can be used either as definitive treatment or while waiting for a new graft to be performed under better conditions.