Simplified Fabrication for Ion-Selective Optical Emulsion Sensor with Hydrophobic Solvatochromic Dye Transducer: A Cautionary Tale.

It has recently been reported that polystyrene microbeads may be modified to realize plasticizer-free ion-selective optical sensors (optodes) on the basis of solvatochromic dye transducers. We show here that the functionalized microbeads, individually isolated by flow cytometry, exhibit unexpectedly poor fluorescent properties and that the sensor response is instead attributed to the supernatant. A more thorough study reveals that such optical microemulsion sensors can be made operationally functional and chemically selective, seemingly in the absence of any solvent matrix or added surfactant. Instead, it is shown that residual THF used in the fabrication of the emulsified sensors may solubilize the sensing components and give a functional optode response. To evaluate this further, the number of sensing components was stepwise simplified to assess their need. Variation of residual THF levels has no effect on the ion optode response when plasticizer is present, in support of established results. Lipophilic solvatochromic dye transducers are also shown not to require an added surfactant as their nature already endows the emulsified sensors with a stabilizing ionic surface charge. The ionophores are shown to exhibit much larger stability constants in the surfactant-free formulations than surfactant-based ones (valionomycin, log ß > 9.2 compared to 6.1; Na+-ionophore X, 6.7 vs 4.7), which is attributed to a less polar solvent environment for the ionophore. Potassium-, sodium-, and calcium-selective sensors were used as model systems in this study.

A sib-pair study of the Temperament and Character Inventory scales in major depression.

BACKGROUND: Certain aspects of the personality may be associated with the vulnerability to develop depression. A sib-pair method has been used to examine the familiality of the 7 scales of the Temperament and Character Inventory (TCI) and whether this could be related to the genetic vulnerability to develop depression. METHODS: Probands with depression and their nearest-aged siblings from Wales were compared with healthy control probands and their nearest-aged siblings on the TCI and measures of depressed mood. RESULTS: All 7 scales of the TCI were familial, and scores on 6 of the scales were similar to US population scores. However, the Welsh subjects' scores on the self-transcendence scale were markedly lower than the US mean, suggesting strong cultural or national influences on this measure. Harm avoidance scores were substantially influenced by current and past depression, but this scale also showed stable traitlike characteristics that are likely related to the genetic vulnerability to depression. Novelty seeking and self-directedness were also partly state-dependent and were negatively correlated with low mood; high scorers may be resilient to the development of depression. High reward dependence may also protect against the development of depression and is unrelated to mood state. The cooperativeness, persistence, and self-transcendence scales appear to have a limited relationship with the development of depression. CONCLUSIONS: Harm avoidance, reward dependence, novelty seeking, and self-directedness have traitlike characteristics that are related to the familiality of depression. Cooperativeness, self-transcendence, and persistence are also familial, but this appears to be unrelated to depression.

Neuroticism, extraversion, life events and depression. The Cardiff Depression Study.

BACKGROUND: Certain personality traits may mediate the relationship between familiality and adversity in causing depression. AIMS: To examine whether the neuroticism and extraversion scales of the Eysenck Personality Inventory (EPI) represent enduring traits underlying the vulnerability to respond to adversity by developing depressive episodes. METHOD: A total of 108 subjects with depression and their siblings were compared with 105 healthy control subjects and their siblings. All were interviewed using the Schedules for the Clinical Assessment of Neuropsychiatry and the Life Events and Difficulties Schedule. Subjects also completed the EPI. RESULTS: Both neuroticism and extraversion were familial and correlated with mood and life event measures. There were no differences on either measure between the never-depressed siblings of probands with depression and controls. Regression analyses showed that the major influence on neuroticism was current mood. CONCLUSIONS: Neither extraversion nor neuroticism measures trait vulnerability to depression, and neuroticism scores mainly reflect symptoms of depression.