Aqueous micelles are capable of solubilizing organic molecules with quite distinct polarities and degrees of hydrophobicity. Experimental Ks values for incorporation of neutral solutes in anionic sodium dodecyl sulfate micelles (SDS; 66 solutes), cationic hexadecyltrimethylammonium (CTAB; 42 solutes) and dodecyltrimethylammonium bromide micelles (DTAB; 39 solutes), and nonionic Brij-35 micelles (19 solutes) exhibited excellent fits (multiple correlation coefficients >0.98; standard deviations <0.2) to the linear solvation free energy relationship (LSER) proposed by Abraham (Chem. Soc. Rev. 1993, 22, 73): log Ks = c + -2 + ¿ /L + sn2 + rR2 + v(Vx/100). The LSER is based on medium-independent parameters for solute hydrogen bond acidity ( 2) and basicity ( ß ), excess molar refraction (R2), dipolarity ( 2), and volume (Vx). For all four detergents, incorporation is dominated by the Vx terms (positive, reflecting the hydrophobic effect) and the ß terms (negative, implying that bulk water is a better hydrogen bond donor than the micellar solubilization site). The contributions of 2 and /?", though smaller, vary in a chemically satisfying manner with detergent charge and stmcture. Incorporation is relatively insensitive to the solute dipolarity 2. These LSERs appear to provide a convenient framework for understanding the factors which contribute to the micellar solubility of organic solutes and for developing quantitative structure-solubility relationships for organized media.
Both preclinical and clinical data link glutamate to the migraine pathophisiology. Altered plasma, platelets and cerebrospinal (CSF) glutamate levels have been reported in migraine patients. Chronic migraine is comorbid with several conditions. It has been recently shown chronic migraine comorbidity with fibromyalgia. The objective of this study was to study cerebrospinal fluid glutamate levels in chronic migraine patients with and without fibromyalgia. We studied 20 chronic migraine patients, with and without fibromyalgia, compared to age-sex matched controls. CSF glutamate levels were measured by HPLC. CSF glutamate demonstrated significantly higher levels in patients with fibromyalgia compared to those without fibromyalgia. Patients overall had higher CSF glutamate levels than controls. Mean pain score correlated with glutamate levels in chronic migraine patients. Tender points, the hallmark of fibromyalgia, can be considered as pressure allodynia, and is probably mediated by central sensitization, with increase in CSF glutamate levels. We postulate chronic migraine patients with fibromyalgia, in addition to have more disabling headaches, suffer from a more severe central sensitization process. This subtype of patients may respond to medications modulating glutamate receptors. Headache intensity correlate with glutamate levels in chronic migraine patients.
Incorporation coefficients for binding of 29 nonionic solutes to cationic/nonionic mixed micelles (1:1
molar ratio of hexadecyltrimethylammonium bromide (CTAB)/ polyoxyethylene[23]dodecyl ether (Brij
35)) were employed to establish a linear solvation free energy relationship (LSER) based on five solute
parameters. Comparison of this LSER with those for solute incorporation into micelles of the pure, unmixed
detergents indicates that hydrogen-bonding interactions are the predominant contributors to the
nonidealities of solubilization in the mixed micelle.
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