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M Perrier

Publications and source records attributed to M Perrier.

51 records · Page 3Linked to original sources
PubMedDate not supplied

Application of multi-wavelength fluorometry for on-line monitoring of an anaerobic digestion process.

This work examined the use of multi-wavelength fluorometry for on-line monitoring of an anaerobic digestion process. Experiments were carried out in a laboratory-scale anaerobic digestor fed with either synthetic or agricultural (cheese factory) wastewater. An in-line fiber optic probe installed in the external recirculation loop of the reactor was used to acquire fluorescence spectra with an interval of 5-10 min. The spectra were compared with analytical measurements taken at the same time to develop regression models, which were then used to predict concentrations of chemical oxygen demand, volatile fatty acids, and other key process parameters. A comparison of partial least squares (PLS), nonlinear principal components regression, and step-wise regression models on an independent set of data showed that the PLS model gave the best prediction accuracy.

Bacteria, Anaerobic↗
PubMedDate not supplied

293SF metabolic flux analysis during cell growth and infection with an adenoviral vector.

Metabolic flux quantification of cell culture is becoming a crucial means to improve cell growth as well as protein and vector productions. The technique allows rapid determination of cell culture status, thus providing a tool for further feeding improvements. Herein, we report on key results of a metabolic investigation using 293 cells adapted to suspension and serum-free medium (293SF) during growth and infection with an adenoviral vector encoding the green fluorescence protein (GFP). The model developed contains 35 fluxes, which include the main fluxes of glycolysis, glutaminolysis, and amino acids pathways. It requires specific consumption and production rate measurements of amino acids, glucose, lactate, NH(3), and O(2), as well as DNA and total proteins biosynthesis rate measurements. Also, it was found that extracellular protein concentration measurement is important for flux calculation accuracy. With this model, we are able to describe the 293SF cell metabolism, grown under different culture conditions in a 3-L controlled bioreactor for batch and fed-batch with low glucose. The metabolism is also investigated during infection under two different feeding strategies: a fed-batch starting at the end of the growth phase and extending during infection without medium change and a fed-batch after infection following medium renewal. Differences in metabolism are observed between growth and infection, as well as between the different feeding strategies, thus providing a better understanding of the general metabolism.

Adenoviridae↗
PubMedDate not supplied

Adaptive control at low glucose concentration of HEK-293 cell serum-free cultures.

Fed-batch cultures were implemented to study the metabolism of HEK-293 cells. Glucose, measured every 30 min by a FIA biosensor system, was maintained at 1 mM throughout the culture using an adaptive nonlinear controller based on minimal process modeling. The controller performed satisfactorily at both low and high cell concentrations without the need for retuning between different culture phases. Overall, lactate production was significantly reduced by maintaining a low glucose concentration, thus decreasing the rate of glycolysis. The rates of glucose and glutamine uptake as well as the lactate and ammonia production were compared to those obtained in batch mode with an initial glucose concentration of 21 mM. Basically, three phases were observed in both culture modes. The metabolic shift from the first to the second phase was characterized by a significant reduction in glucose consumption and lactate production while maximum growth rate was maintained. The specific respiration rate appeared unchanged during the first two phases, suggesting that no change occurred in the oxidative pathway capacity. In the third phase, cell growth became slower very likely due to glutamine limitation.

Ammonia↗
PubMedDate not supplied

Somatosensory evoked potentials from posterior tibial nerve; normative data.

The somatosensory evoked potentials from posterior tibial nerve were studied in a group of normal adults. The latencies of popliteal fossa potential, L3, N33 and P40 waves as well as central conduction time were analyzed as a function of height and age. The correlation of the peripheral conduction velocity with the subject's age was also studied. The corresponding regression formulae were calculated and can be used to predict normal values of these parameters over a wide range of height and age. Standard error estimates are given for all parameters.

Adult↗
PubMedDate not supplied

[Basedow's disease: recurrence after surgical treatment. Study of a series of 88 patients].

A homogeneous series of 88 patients with a history of surgery for Basedow's disease was studied retrospectively to evaluate long term recurrences. A total of 88 cases were reviewed after a follow up of a median of 50 months (range 1 to 13 years), and hormone assays were carried out in 74 cases. Surgical complications were minor: no mortality, no definitive hypoparathyroidism, 45% unilateral recurrent nerve palsies and 14.3% definitive hypothyroidism occurring during the first year. Fifteen patients had one or several recurrences of hyperthyroidism. The actuarial recurrence rate at 5 years was 17%, the risk increasing progressively up to the sixth year. The type of operation was the only predictive factor of recurrence surveillance of these patients should be prolonged and involve regular hormone assays, since 6 of the 15 recurrences were poorly symptomatic.

Adolescent↗
PubMedDate not supplied

[Acute renal failure following intravenous urography. 4 cases (author's transl)].

The authors report on 4 cases of acute oligo-anuric renal failure that followed intravenous urography (IVU) independently from myeloma or cardiovascular collapse. Eighty other cases can be found in the literature. Post-IVU renal failure only occurs in patients already presenting with chronic renal insufficiency, those with diabetic or geriatric arterial disease being particularly at risk. It is reversible in only one out of two cases when serum creatinine levels exceed 440 mumol/l. The various triiodide contrast media with a high osmolality are equally nephrotoxic. The pathophysiology and prevention of this complication of IVU are discussed.

Acute Kidney Injury↗