In-storage psychrophilic anaerobic digestion: acclimated microbial kinetics.

In-storage psychrophilic anaerobic digestion develops by microbial acclimation in covered swine-manure storage tanks, producing CH4 and stabilizing organic matter. To optimize the system's performance, the process kinetics must be understood. The objective of this study was to evaluate kinetic parameters describing the major stages in the digestion process, and to investigate the effect of temperature acclimation on these parameters. Specific activity tests were performed using manure inocula and five substrates at three incubation temperatures. Extant substrate activities were determined analytically for each case, and intrinsic kinetic parameters for glucose uptake were estimated by grid search fitting to the Monod model. The results demonstrate that this acclimated microbial community exhibits different kinetic parameters to those of the mesophilic communities currently modelled in the literature, with increased activity at low temperatures, varying with substrate and temperature. For glucose, the higher uptake is accompanied by lower microbial yield and half-saturation constant. Decomposing these values suggests that active psychrophilic and mesophilic microbial populations co-exist within the community. This work also confirms that a new method of assessing microbial substrate kinetics must be developed for manure microbial communities, separating microbial mass from other suspended organics.

[Potentiation strategies]. / Dépression résistante : les stratégies de potentialisation.

Lithium is among the most classically recommended add-on therapeutic strategy for the management of depressive patients showing unsuccessful response to standard antidepressant medications. The effectiveness of the add-on strategy with lithium requires achieving plasma levels above 0.5 mEq/L. Mood-stabilizing antiepileptic drugs such as carbamazepine, valproate derivatives or lamotrigine have not demonstrated conclusive therapeutic effects for the management of depressive patients showing unsuccessful response to standard antidepressant medications. Thyroid hormones are considered among the currently recommended add-on therapeutic strategy for the management of depressive patients showing unsuccessful response to standard antidepressant medications. The effectiveness of the add-on strategy with thyroid hormones requires achieving plasma concentration of TSH close to the lower limits at the normal range (0.4 µUI/L) or even below it. Second-generation antipsychotics such as aripiprazole or quetiapine have consistently demonstrated significant therapeutic effects for the management of depressive patients showing unsuccessful response to standard antidepressant medications. Second-generation antipsychotics however require the careful monitoring of both cardiovascular and metabolic adverse effects.

[How to define treatment-resistant depression?]. / Quelle définition pour la dépression résistante ?

The most largely used definition of the treatment-resistant depression relies on the failure of two successive trials of antidepressant treatment at an adequate dose and duration. The absence of response to previous antidepressant treatments should be assessed using specific and appropriate clinical instruments enabling a correct staging of the therapeutic resistance. A wide range of socio-demographic and clinical factors (i.e. psychiatric/somatic comorbidities) are classically associated with the therapeutic resistance. The aim of the treatment of major depression is to achieve a complete clinical remission. The presence of residual symptoms increases the risk for the subsequent occurrence of relapses and recurrences, hence facilitating the development of therapeutic resistance. The treatment-resistant depression has a deleterious impact on the social, familial or professional functioning, thereby leading to an impaired quality of life with serious socioeconomic consequences and costs.

[Other therapeutic strategies]. / Dépression résistante : les autres stratégies thérapeutiques.

Non-selective and irreversible MAOI have become as third or fourth-line strategy for the management of treatment-resistant depression. Non-selective and irreversible MAOI requires careful monitoring of drug interactions and dietary restrictions. Nutritional supplements such as omega-3 have been found to produce beneficial effects in the management of treatment-resistant depression when administered in combination with the ongoing antidepressant treatment. The glutamate antagonist ketamine has been found to produce beneficial effects in the management of treatment-resistant depression while administered alone. Dopamine and/or norepinephrine agonists, such as methylphenidate, modafinil or pramipexole, have been found to produce beneficial effects in the management of treatment-resistant depression when administered in combination with the ongoing antidepressant treatment.

[Switching and combining strategies of antidepressant medications]. / Dépression résistante : les stratégies de changement et d'association de médicaments antidépresseurs.

Switching antidepressant medication may be helpful in depressed patients having no benefit from the initial antidepressant treatment. Before considering switching strategy, the initial antidepressant treatment should produce no therapeutic effect after at least 4 weeks of administration at adequate dosage. Choosing an antidepressant of pharmacologically distinct profile fails to consistently demonstrate a significant superiority in terms of effectiveness over the switching to another antidepressant within the same pharmacological class. Augmenting SSRI/SNRIs with mirtazapine/mianserin has become the most recommended strategy of antidepressant combinations. Augmenting SSRI with tricyclic drugs is now a less recommended strategy of antidepressant combinations given the increased risk for the occurrence of pharmacokinetic drug-drug interactions and adverse effects.