Background There is a growing body of literature highlighting the role that wearable and mobile remote measurement technology (RMT) can play in measuring symptoms of major depressive disorder (MDD). Outcomes assessment typically relies on self-report, which can be biased by dysfunctional perceptions and current symptom severity. Predictors of depressive relapse include disrupted sleep, reduced sociability, physical activity, changes in mood, prosody and cognitive function, which are all amenable to measurement via RMT. This study aims to: 1) determine the usability, feasibility and acceptability of RMT; 2) improve and refine clinical outcome measurement using RMT to identify current clinical state; 3) determine whether RMT can provide information predictive of depressive relapse and other critical outcomes. Methods RADAR-MDD is a multi-site prospective cohort study, aiming to recruit 600 participants with a history of depressive disorder across three sites: London, Amsterdam and Barcelona. Participants will be asked to wear a wrist-worn activity tracker and download several apps onto their smartphones. These apps will be used to either collect data passively from existing smartphone sensors, or to deliver questionnaires, cognitive tasks, and speech assessments. The wearable device, smartphone sensors and questionnaires will collect data for up to 2-years about participants’ sleep, physical activity, stress, mood, sociability, speech patterns, and cognitive function. The primary outcome of interest is MDD relapse, defined via the Inventory of Depressive Symptomatology- Self-Report questionnaire (IDS-SR) and the World Health Organisation’s self-reported Composite International Diagnostic Interview (CIDI-SF). Discussion This study aims to provide insight into the early predictors of major depressive relapse, measured unobtrusively via RMT. If found to be acceptable to patients and other key stakeholders and able to provide clinically useful information predictive of future deterioration, RMT has potential to change the way in which depression and other long-term conditions are measured and managed. Electronic supplementary material The online version of this article (10.1186/s12888-019-2049-z) contains supplementary material, which is available to authorized users.

This study describes the regioselective hydroxylation and the rates of conversion of a series of fluorinated phenol derivatives by phenol hydroxylase from the yeast Trichosporon cutuneurn. The natural logarithm of the k,,, value for the conversion of the phenolic substrates correlates with the calculated energy of the reactive electrons in the highest occupied molecular orbital of the substrate ( r = 0.85). This observation supports the hypothesis that at physiological pH (7.6) and 25"C, in the absence of monovalent anions, the nucleophilic attack of the electrons in the highest occupied molecular orbital of the substrate on the C(4a)-hydroperoxyflavin enzyme intermediate is of major importance in determining the overall rate of catalysis. Results from 19F-NMR analysis of the incubation mixtures demonstrate for phenols with two identical ortho substituents, that the ortho position which becomes preferentially hydroxylated is the one with the highest density of the reactive electrons in the highest occupied molecular orbital. A halogen substituent at a metu position decreases the chances for hydroxylation at the adjacent ortho position further than expected on the basis of the calculated reactivity. This result indicates a contribution of a proteinkubstrate dipolar interaction, influencing the time-averaged orientation of the substrate with respect to the reactive C(4a)-hydroperoxyflavin intermediate. Keywords.Flavin ; 29F-NMR ; molecular orbital ; monooxygenase ; phenol hydroxylase.Phenol hydroxylase is a flavin-dependent monooxygenase that can be isolated from a variety of sources, e.g. bacteria, actinomycetes and yeasts. The present study focuses on the phenol hydroxylase from the strictly aerobic yeast Trichosporon cumneurn [l]. The catalytic mechanism of the enzyme is reported to proceed by formation of a C(4a)-hydroperoxyflavin intermediate, formed upon two-electron reduction of the flavin prosthetic group by NADPH, incorporation of an oxygen molecule, and protonation of the lperoxy moiety [l -31. The mechanism by which the C(4a)-hydroperoxyflavin intermediate converts the substrate to its hydroxylated form is supposed to proceed analogously to the mechanism for other aromatic hydroxylases, i.e. by an electrophilic attack of the hydroperoxide function on the substrate [4-61. The enzyme has been reported to catalyse the hydroxylation of a variety of substituted phenols, such as fluoro-, chloro-, amino-and methyl-phenols and also dihydroxybenzenes, at the ortho position with respect to the hydroxyl moiety [7, 81. The reaction cycle consists of various separate steps and is supposed to proceed by successive substrate binding, NADPH binding, flavin reduction, NADP' release, oxygen Correspondence to S. Peelen, Department of Biochemistry, Agricultural University, Dreijenlaan 3, NL-6703 HA Wageningen, The Netherlands Fax: +31 8370 84801. Abbreviations. MO-QSAR, molecular-orbital-based quantitative structure-activity relationship; HOMO, highest occupied molecular orbital; E(HOMO), energy of the highest occupied mol...

The cytochrome P450 (P450) catalyzed 4-hydroxylation of halogenated anilines was investigated with special emphasis on possible relationships between kinetic parameters and physicochemical and electronic characteristics of the substrates. The most important observation of the present study was a correlation (r = 0.96) between the natural logarithm of the apparent maximum reaction rate kcats for 4-hydroxylation of the aniline substrates in a iodosobenzene-supported microsomal cytochrome P450-catalyzed reaction and the energy of the highest molecular orbital [E(HOMO)] of the anilines. This result is in accordance with a mechanism that proceeds by an initial electrophilic attack of the P450 (FeO)3+ intermediate on the frontier pi electrons of the aniline substrates. In the iodosobenzene-supported aniline 4-hydroxylation this electrophilic attack is the rate-limiting step. In the NADPH/oxygen-supported cytochrome P450-catalyzed 4-hydroxylation of the anilines a correlation of the natural logarithm of kcats with E(HOMO) was not observed and the kcats values were lower than observed in the iodosobenzene-supported reaction. From this result it is concluded that, although the NADPH/oxygen-supported microsomal 4-hydroxylation of the halogenated anilines proceeds by the same cytochrome P450 (FeO)3+ intermediate and, thus, by a similar electrophilic attack of the (FeO)3+ on the pi electrons of the substrate, this attack is no longer the rate-limiting step of the reaction. Additional results of the present study demonstrate that the apparent Michaelis constant Kms of the NADPH/oxygen-supported 4-hydroxylation of the anilines decreases with increasing hydrophobicity of the aniline derivatives.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophage M13 major coat protein has been isolated with cholate and reconstituted in dimyristoyl- and dioleoylphosphatidylcholine (DMPC and DOPC, respectively) bilayers by dialysis. Fourier transform infrared spectra of DMPC/coat protein recombinants confirmed that, whereas the protein isolated by phenol extraction was predominantly in a beta-sheet conformation, the cholate-isolated coat protein contained a higher proportion of the alpha-helical conformation [cf. Spruijt, R. B., Wolfs, C. J. A. M., & Hemminga, M. A. (1989) Biochemistry 28, 9158-9165]. The cholate-isolated coat protein/lipid recombinants gave different electron spin resonance (ESR) spectral line shapes of incorporated lipid spin labels, as compared with those from recombinants with the phenol-extracted protein that were studied previously [Wolfs, C. J. A. M., Horváth, L. I., Marsh, D., Watts, A., & Hemminga, M. A. (1989) Biochemistry 28, 9995-10001]. Plots of the ratio of the fluid/motionally restricted components in the ESR spectra of spin-labeled phosphatidylglycerol were linear with respect to the lipid/protein ratio in the recombinants up to 20 mol/mol. The corresponding values of the relative association constants, Kr, and number of association sites, N1, on the protein were Kr approximately 1 and N1 approximately 4 for DMPC recombinants and Kr approximately 1 and N1 approximately 5 for DOPC recombinants. Simulation of the two-component lipid spin label ESR spectra with the exchange-coupled Bloch equations gave values for the off-rate of the lipids leaving the protein surface of 2.0 x 10(7) s-1 at 27 degrees C in DMPC recombinants and 3.0 x 10(7) s-1 at 24 degrees C in DOPC recombinants.(ABSTRACT TRUNCATED AT 250 WORDS)

The regioselectivity and rate of the ortho-hydroxylation of 3-fluorophenol by phenol hydroxylase from Trichosporon curuneum (EC 1.14.13.7) was studied using 19F-NMR. The regioselective hydroxylation as well as the rate of orrho-hydroxylation are pH dependent with a pKa of 6.5. At pH values below 6.5, 3-fluorophenol preferentially becomes hydroxylated at the C6 ortho position, resulting in a maximum C6/C2 hydroxylation ratio of 6.7. Upon increasing the pH, the total rate of conversion increases. Also, the C2 ortho-hydroxylation increases relatively to the C6 orthohydroxylation and yields a minimum C6/C2 hydroxylation ratio of 2.2 at pH values above 7.5.Based on data from I9F-NMR binding studies and molecular orbital calculations, a hypothesis is put forward which explains the pH-dependent effects observed. A mechanism is proposed involving an active-site amino acid residue acting as a base in the reduced form of the protein. Deprotonation of this residue results in hydrogen bond formation with the hydroxyl moiety of the phenolic substrate, leading to (partial) deprotonation of the substrate. Molecular orbital calculations demonstrate that such a (partial) deprotonation increases (a) the overall reactivity of 3-fluorophenol for an electrophilic attack and (b) the reactivity of C2 relative to the C6 position. The hypothesis may explain the decrease in the C6/C2 hydroxylation ratio. Furthermore the increased amount of orthohydroxylated products formed with increasing pH can also be explained by this hypothesis.Phenol hydroxylase from Trichosporoa cutaneurn is one of the many flavin-dependent aromatic hydroxylases [l 1. The enzyme catalyses the conversion of phenol to 1 ,Zdihydroxybenzene (catechol). The monooxygenase phenol hydroxylase is a homodimer (molecular mass 152 kDa), each subunit containing a non-covalently bound FAD [2]. Unlike most bacterial flavin-dependent aromatic hydroxylases, eukaryotic phenol hydroxylase shows a rather broad substrate specificity. In addition to the parent substrate phenol, the enzyme also catalyses the hydroxylation of various substituted phenols such as o-, m-and p-fluorophenol, m-and p-chlorophenol, aminophenols, dihydroxybenzenes and cresol [3, 41.The catalytic mechanism of the enzyme is reported to proceed by formation of a C(4a)-hydroperoxyflavin intermediate, formed upon two-electron reduction of the flavin prosthetic group by NADPH and incorporation of an oxygen molecule [3, 51. The mechanism by which the C(4a)-hydroperoxyflavin intermediate converts the substrate to its hydroxylated form is supposed to proceed analogously to the mechanism for other aromatic hydroxylases, i.e. by an elec- trophilic attack of the peroxide function, or a hydroxyl radical derived from it, on the substrate [6-lo]. The nature in which the substrate reacts, however, is still a matter of debate. Despite the availability of the recently determined amino acid sequence [ll], it is not clear which amino acid residues participate in catalysis. Binding of phenol was reported to be favored at higher pH va...