A study of medication compliance, side effects, and clinical change with the use of antidepressants in 32 Southeast Asian refugee patients seen at an urban mental health center is reported. Patients met criteria for either major depressive episode, posttraumatic stress disorder, or both. Only five of the 32 patients who stated that they were taking their medications regularly had antidepressant blood levels in the therapeutic range. Another 10 patients had subtherapeutic levels and the remaining 17 had undetectable blood levels. Patients with therapeutic blood levels had fewer side effects (p = 0.049) than patients with undetectable blood levels. Blood levels tended (p = 0.070) to be correlated with clinical improvement. The authors discuss cultural attitudes of Southeast Asian refugee patients toward medication use and side effects that appear to influence medication compliance.
Enzymes from thermophilic and hyper-thermophilic organisms have an intrinsic high stability. Understanding the mechanisms behind their high stability will be important knowledge for the engineering of novel enzymes with high stability. Lysine methylation of proteins is prevalent in Sulfolobus, a genus of hyperthermophilic and acidophilic archaea. Both unspecific and temperature dependent lysine methylations are seen, but the significance of this post-translational modification has not been investigated. Here, we test the effect of eliminating in vivo lysine methylation on the stability of an esterase (EstA). The enzyme was purified from the native host S. islandicus as well as expressed as a recombinant protein in E. coli, a mesophilic host that does not code for any machinery for in vivo lysine methylation. We find that lysine mono methylation indeed has a positive effect on the stability of EstA, but the effect is small. The effect of the lysine methylation on protein stability is secondary to that of protein expression in E. coli, as the E. coli recombinant enzyme is compromised both on stability and activity. We conclude that these differences are not attributed to any covalent difference between the protein expressed in hyperthermophilic versus mesophilic hosts.
What is known and objective Pharmacogenomic biomarkers are now used in many clinical care settings and represent one of the successes of precision medicine. Genetic variants are associated with pharmacokinetic and pharmacodynamic changes leading to medication adverse effects and changes in clinical response. Actionable pharmacogenomic variants are common in transplant recipients and have implications for medications used in transplant, but yet are not broadly incorporated into practice. Methods From the Clinical Pharmacogenetics Implementation Consortium and Dutch Pharmacogenetics Working Group guidelines, and PharmGKB databases, 12 pharmacogenomic genes with 30 variants were selected and used to create diplotypes and actionable pharmacogenomic phenotypes. A total of 853 kidney allograft recipients who had genomic information available from a genome-wide association study were included. Results Each recipient had at least one actionable pharmacogenomic diplotype/phenotype, whereas the majority (58%) had three or four actionable diplotypes/phenotypes and 17.4% had five or more among the 12 genes. The participants carried actionable diplotypes/phenotypes for multiple medications, including tacrolimus, azathioprine, clopidogrel, warfarin, simvastatin, voriconazole, antidepressants and proton-pump inhibitors. What is new and conclusion Pharmacogenomic variants are common in transplant recipients, and transplant recipients receive medications that have actionable variants. Clinical trial Genomics of Transplantation, clinicaltrials.gov (NCT01714440).
In this work, we use coarse-grained modeling to study the free solution electrophoretic mobility of small highly charged peptides (lysine, arginine, and short oligos thereof (up to nonapeptides)) in NaCl and Na2SO4 aqueous solutions at neutral pH and room temperature. The experimental data are taken from the literature. A bead modeling methodology that treats the electrostatics at the level of the nonlinear Poisson Boltzmann equation developed previously in our laboratory is able to account for the mobility of all peptides in NaCl, but not Na2SO4. The peptide mobilities in Na2SO4 can be accounted for by including sulfate binding in the model and this is proposed as one possible explanation for the discrepancy. Oligo arginine peptides bind more sulfate than oligo lysines and sulfate binding increases with the oligo length.
Liposomes have attracted intensive attention as drug delivery systems in anti-cancer therapy. Since liposomes are constructed by self-assembling of phospholipids, ICP-MS is a suitable method for simultaneous determination of liposomes and encapsulated metallic drug substances such as platinum-based drugs. An efficient method for simultaneous determination of phosphorus and platinum in liposome samples has been established based on the use of xenon as a collision gas in DRC-ICP-MS. Under the optimum conditions with respect to signal to noise ratio, the interferences were suppressed and the detection limits of phosphorus and platinum were 0.3 and 0.05 ng mL−1, respectively. Quality control was performed by using a certified reference material BCR 273 and biological reference materials. For the purpose of investigation of liposome stability and metallo-drug release from liposomes, a hyphenated method based on size exclusion chromatography was developed for separation of free and encapsulated platinum in a model liposome formulation of oxaliplatin. Moreover, an accelerated drug release study was performed by sonication of liposomal samples and using the developed hyphenated method to determine the drug leakage. It has been demonstrated that the SEC-DRC-ICP MS method was an efficient tool in the development and characterization of liposome based formulations of metallic drugs.
Recently, an enzymatic reaction was utilized to covalently link the N and C termini of membrane scaffold proteins to produce circularized nanodiscs that were more homogeneous and stable than standard nanodiscs. We continue this development and aim for obtaining high yields of stable and monodisperse nanodiscs for structural studies of membrane proteins by solution small‐angle scattering techniques. Based on the template MSP 1E3D1, we designed an optimized membrane scaffold protein (His‐ls MSP 1E3D1) with a sortase recognition motif and high abundance of solubility‐enhancing negative charges. With these modifications, we show that high protein expression is maintained and that the circularization reaction is efficient, such that we obtain a high yield of circularized membrane scaffold protein (cs MSP 1E3D1) and downstream circularized nanodiscs. We characterize the circularized protein and corresponding nanodiscs biophysically by small‐angle X‐ray scattering, size‐exclusion chromatography, circular dichroism spectroscopy, and light scattering and compare to noncircularized samples. First, we show that circularized and noncircularized (ls MSP 1E3D1) nanodiscs are structurally similar and have the expected nanodisc structure. Second, we show that ls MSP 1E3D1 nanodiscs are more stable compared to the template MSP 1E3D1 nanodiscs as an effect of the extra negative charges and that cs MSP 1E3D1 nanodiscs have further improved stability as an effect of circularization. Finally, we show that a membrane protein can be efficiently incorporated in cs MSP 1E3D1 nanodiscs. Large‐scale production methods for circularized nanodiscs with improved thermal and temporal stability will facilitate better access to the nanodisc technology and enable applications at physiologically relevant temperatures.
