Chiral separations by capillary electrochromatography using molecularly imprinted polymers.
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Chromatography↗
Biomedical subjects
Staffan Nilsson
Publications and source records attributed to Staffan Nilsson.
Mutations in the N-terminal domain of DFF45 in a primary germ cell tumor and in neuroblastoma tumors.
DFF45 has essential functions in the final stage of apoptosis by acting both as a folding chaperone and a DNase inhibitor of DFF40. The gene encoding DFF45 (DFFA) maps to the consensus deleted region in primary neuroblastoma (NB; 1p36.2-3) and within the homozygously deleted region in an NB cell line (1p36.2). DFF45 is therefore an attractive candidate NB tumor suppressor. In a previous study we found a rare allele variant, causing a non-polar to a polar amino acid exchange (Ile69Thr) in a preserved hydrophobic patch of DFF45, and we also found DFFA to be preferentially expressed in favorable NB tumors. We have extended the previous study and performed mutation analyses in another 56 NB tumors (100 in total) as well as a set of other tumors for coding mutations in DFFA. We have also performed studies of the DFFA expression in tumors using real-time PCR. We found a missense mutation (Ile15Met) in the remaining allele of a teratoma with heterozygous deletion of 1p, and a three base-pair deletion in an NB of unknown stage causing a deletion of amino acid 37 in DFF45. The one-base substitution detected in the teratoma was not present in the patients constitutional DNA, i.e. it is a true mutation present in the tumor DNA only. In conclusion, three different coding alterations have been found in the region encoding the N-terminal regulatory domain of DFF45, responsible for binding and achieving its chaperone and inhibitor functions on other proteins. Moreover, by real-time RT-PCR expression study, we found the mRNA level of DFFA to be significantly (p=0.038) reduced by a factor of 1.7 times in NB tumors of unfavorable outcome.
Apoptosis↗
Analysis of 6 genetic loci for disease susceptibility in psoriatic arthritis.
OBJECTIVE: To analyze the association of several autoimmune disease susceptibility loci in a population of patients with psoriasis and defined joint disease from northern Sweden. METHOD: One hundred twenty patients with psoriasis and defined joint disease were examined clinically, radiologically, and with laboratory-based analyses. Disease classification was based on peripheral and/or axial engagement. The tumor necrosis factor (TNF) locus, 1q21 (PSORS4), 3q21 (PSORS5), 8q24, 16q21, and the CTLA4 gene were analyzed using a total of 38 microsatellite markers and 2 single nucleotide polymorphisms (SNP). Ninety-four controls with the same ethnic background as the patients were randomly selected from the same region of Sweden. RESULTS: An association was found with one of the markers in the TNFB locus within the HLA region (p = 0.012, pc = 0.024). Three markers at the PSORS4 locus on chromosome 1q21 and 2 markers at the 8q24 locus showed nominal p values of < 0.05. After applying the Bonferroni correction for multiple analyses these markers did not reach significance. No other marker showed significant association. In a subgroup of the patients, possible linkage disequilibrium between the TNFB123 and HLA-B antigens, B17, B27, B37, B44, and B62 was analyzed. A significant linkage (p = 0.0001) was found. CONCLUSION: We identified an association between psoriatic arthritis and one of the microsatellite markers within the TNFB locus at the HLA region on chromosome 6. Linkage disequilibrium between TNFB123 and certain HLA-B antigens was found.
Adult↗
Selectivity toward multiple predetermined targets in nanoparticle capillary electrochromatography.
Two unique methods to achieve selectivity toward multiple predetermined targets employing molecular imprinting technology have been developed. Partial filling capillary electrochromatography (CEC) was utilized to evaluate and compare the two techniques. The first approach, the mixed singly templated molecularly imprinted polymer (MIP) nanoparticle approach, is based on the mixing of two types of MIP nanoparticles with inherently different selectivity. The second approach, the multiply templated MIP nanoparticle approach, is based on the incorporation of two different templates during the preparation of the MIP nanoparticles. The use of MIPs in analytical chemistry applications has been extensively investigated during the past years. However, MIP nanoparticles with tailored multiple selectivity toward predetermined enantiomers has not yet been explored. The relative amounts of the two templates studied, i.e., (S)-ropivacaine and (S)-propranolol, were found to strongly affect the affinity of the multiply templated MIP nanoparticles for the predetermined targets. The amount of (S)-propranolol template had to be decreased to concentrations rarely applied in MIP synthesis in order to achieve 2-fold selectivity. Even though strongly decreased to 10% of the usual concentration employed, the MIP could efficiently separate the enantiomers of propranolol when applied in partial filling CEC. This opens up for new possibilities to decrease the need for an initial high amount of template in order to be able to produce an efficient MIP. The multiple enantiomer separation ability of the multiply templated MIP nanoparticles was compared with that of singly templated MIP nanoparticles that were mixed prior to analysis. It was concluded that the multiply templated MIP potentially can offer many new and interesting applications in chromatography as well as in sensor technology and solid-phase extraction.
Journal Article↗
Altered gene expression of folate enzymes in adjacent mucosa is associated with outcome of colorectal cancer patients.
PURPOSE: The purpose of this study was to analyze whether gene expression levels of folate enzymes in adjacent mucosa were associated with outcome of colorectal cancer patients. EXPERIMENTAL DESIGN: Real-time PCR was used to quantify expression levels of folate-associated genes including the reduced folate carrier (RFC-1), folylpolyglutamate synthase (FPGS), gamma-glutamyl hydrolase (GGH),and thymidylate synthase (TS) in tumor tissue and adjacent mucosa of patients with primary colorectal cancer (n=102). Furthermore, reduced folates in the tissues were measured with a binding-assay method. RESULTS: Mean gene expression levels of RFC-1, FPGS, GGH, and TS were significantly higher in tumor biopsies compared with mucosa. Univariate and multivariate analyses showed that the FPGS gene expression level in mucosa, but not in tumor, was a prognostic parameter independent of the clinicopathological factors with regard to survival. Patients with high FPGS levels (>0.92) in mucosa also showed significantly higher total folate concentrations (P=0.03) and gene expression levels of RFC-1 (P<0.01), GGH (P<0.01), and TS (P=0.04) compared with patients with low FPGS levels. The total reduced folate concentration correlated with the gene expression levels of RFC-1 and FPGS but not with TS or GGH. CONCLUSION: Our results suggest that normal-appearing colonic mucosa adjacent to primary colon cancer can show altered gene expression levels of FPGS that may have bearing on the development of aggressive metastatic behavior of the tumor and on tumor-specific survival.
Aged↗
Airborne chemistry coupled to Raman spectroscopy.
In this paper, the use of airborne chemistry (acoustically levitated drops) in combination with Raman spectroscopy is explored. We report herein the first Raman studies of crystallization processes in levitated drops and the first demonstration of surface-enhanced Raman scattering (SERS) detection in this medium. Crystallization studies on the model compounds benzamide and indomethacin resulted in the formation of two crystal modifications for each compound, suggesting that this methodology may be useful for investigation of polymorphs. SERS detection resulted in a signal enhancement of 27 000 for benzoic acid and 11 000 for rhodamine 6-G. The preliminary results presented here clearly indicate that several important applications of the combination between Raman spectroscopy and acoustic drop levitation can be expected in the future.
Journal Article↗
Screening of nucleation conditions using levitated drops for protein crystallization.
The growth of suitable protein crystals is an essential step in the structure determination of a protein by X-ray crystallography. At present, crystals are mostly grown using trial-and-error procedures, and protocols that rapidly screen for the crystal nucleation step are rare. Presented here is an approach to minimize the consumption of precious protein material while searching for the nucleation conditions. Acoustically levitated drops of known protein concentration (0.25-1.5-microL volumes) are injected with crystallizing agents using piezoelectric flow-through dispensers (ejecting 50-100-pL droplets at 1-9000 droplets/s). A restricted number of crystallizing agents representing three classes are used: poly(ethylene glycol), salts, and the viscous alcohol 2-methyl 2,4-pentanediol. From a digitized picture of the levitated drop volume, calculations are performed giving the concentrations of all components in the drop at any time during a "precipitation experiment". Supersaturation is the prerequisite for crystal nucleation, and protein precipitation indicates high supersaturation. A light source illuminates the levitated drop, and protein precipitation is monitored using right-angle light scattering. On the basis of these intensity measurements and the volume determination, precipitation diagrams for each crystallizing agent are constructed that give the protein/crystallizing agent concentration boundaries between the minimum and the maximum detectable protein precipitation. Guided by the concentration values obtained from such plots, when approaching the supersaturation region, separate crystallization drops are mixed and allowed to equilibrate under paraffin oil. At conditions in which microcrystals can be observed, the nucleation tendency of the macromolecule is confirmed. Optimization of crystallization conditions can then follow. Proteins tested include alcohol dehydrogenase and D-serine dehydratase. Alcohol dehydrogenase, known to crystallize easily, was used to evaluate whether the ultrasonic field inhibits nucleation. Details are given for the screening procedure of D-serine dehydratase, an enzyme earlier found to be difficult to crystallize reproducibly. The time and material-saving qualities of this method are emphasized, since a range of conditions can quickly be screened using small amounts of protein to roughly determine solubility characteristics of a protein before crystallization trials are initiated.
Alcohol Dehydrogenase↗
A polymorphism in the serotonin receptor 3A (HTR3A) gene and its association with harm avoidance in women.
BACKGROUND: The brain neurotransmitter serotonin is known to affect various aspects of human behavior, including personality traits. Serotonin receptor type 3 is a ligand-gated channel encoded by 2 different subunit genes, HTR3A and HTR3B. A polymorphism (C178T) in the 5' region of the HTR3A gene has recently been identified and suggested to be of functional importance. OBJECTIVE: To elucidate the possible association between the C178T polymorphism in the HTR3A gene and personality traits in women. DESIGN: Two independent samples of 35- to 45-year-old Swedish women were recruited using the population register. Sample 1 (n = 195) was assessed via the Karolinska Scales of Personality and the Temperament and Character Inventory; sample 2 (n = 175) was assessed using the latter only. Both samples were genotyped with respect to the C178T polymorphism in the HTR3A gene. The A1596G polymorphism in the same gene was also investigated. RESULTS: A significant association between C178T genotype and the Temperament and Character Inventory factor harm avoidance was observed in sample 1 (corrected for multiple comparisons P =.04); this finding was subsequently replicated in sample 2 (P =.004) (pooled populations: P<.001). In the pooled sample, all harm avoidance subscales were found to be significantly associated with the C178T polymorphism: anticipatory worry (P =.001), fear of uncertainty (P<.001), shyness (P<.001), and fatigability and asthenia (P =.008). In addition, a significant association was found in sample 1 between the C178T polymorphism and the Karolinska Scales of Personality nonconformity factor (corrected P =.002), including the subscales of social desirability (P<.001), indirect aggression (P =.002), verbal aggression (P =.05), and irritability (P<.001). Participants homozygous for the less common T allele (<4%) differed from the remaining women by displaying lower ratings on harm avoidance and nonconformity. CONCLUSION: The C178T polymorphism in the HTR3A gene may affect the personality trait of harm avoidance in women.
Adult↗
Molecularly imprinted polymers in capillary electrochromatography: recent developments and future trends.
The developments in molecularly imprinted polymer (MIP)-based capillary electrochromatography (CEC) achieved during the past years are reviewed in this article. The MIP is prepared using a templated polymerization reaction and results in a material with a high selectivity towards a predetermined target. The selectivity of the MIP is comparable to that of the biological antibodies, however, the MIP is much more stable and is thus able to withstand extremely harsh conditions in terms of pH, temperature, and organic solvents. The high selectivity and stability of the MIP made it an interesting candidate for application as stationary phase sorbent in chromatography. However, due to slow kinetics the efficiency of the early MIP columns, which were predominantly applied in high-performance liquid chromatography (HPLC), were limited. The use of CEC was thought to improve the efficiency of the MIP-based separation system. The small dimensions of the capillary format employed in CEC have put demands on the polymer systems which have resulted in the development of many different polymer formats. Thus, this need for novel MIP formats for applications in CEC has contributed a lot to the general development of MIP formats as well as to the knowledge in MIP synthesis and characteristics.
Chromatography, Micellar Electrokinetic Capillary↗
Meta and pooled analysis of European coeliac disease data.
Four full genome scans have been carried out by the partners of the European cluster on coeliac disease as well as follow-up studies of candidate regions. No region outside HLA showed significant linkage to the disease in any single study. We first applied a meta-analysis based on a modification of Genome Screen Meta-Analysis to take into account the different linkage statistics, the arbitrariness of bin cutoff points, as well as the sample size of each study. We then performed a pooled linkage analysis of all families and raw genotypes. Besides the HLA region, already known to harbour a risk factor for coeliac disease, both approaches leave very little doubt on the presence of a genetic risk factor in the 5q31-33 region. This region was suggested by several individual studies, but did not reach statistical values high enough to be conclusive when data sets were analysed separately.
Celiac Disease↗
Nanoparticles as pseudostationary phase in capillary electrochromatography/ESI-MS.
A novel technique that uses polymer nanoparticles as pseudostationary phase in capillary electrochromatography with electrospray ionization mass spectrometry detection is described. A continuous full filling technique in which the nanoparticles were suspended in the entire electrolyte volume as well as a conventional partial filling technique is presented. No nanoparticles entered the mass spectrometer, which was fitted with an orthogonal electrospray interface, despite the continuous flow of nanoparticles into the interface. Nanoparticles (average diameter 160 nm) were prepared from methacrylic acid, methyl methacrylate, and trimethylolpropane trimethacrylate by utilizing a precipitation polymerization technique. Salbutamol, nortriptyline, and diphenhydramine were used as analytes. The interaction between analytes and nanoparticles was found to be predominantly ionic.
Journal Article↗
Risk factors for invasive epithelial ovarian cancer: results from a Swedish case-control study.
This case-control study evaluated reproductive and other factors in relation to epithelial ovarian cancer (EOC) risk. Between 1993 and 1995, the authors recruited 655 EOC cases and 3,899 population controls aged 50-74 years who were born in and residents of Sweden. Data were collected through mailed questionnaires. Odds ratios were estimated by unconditional logistic regression. Parity reduced EOC risk (odds ratio = 0.61, 95% confidence interval (CI): 0.46, 0.81) for uniparous compared with nulliparous women. The risk of EOC decreased with incomplete pregnancies, early menopausal age, late age at first birth, and unilateral oophorectomy; increased with family history of ovarian cancer; and was not associated with menarcheal age, lactation, irregular menses, and menopausal symptoms. Histology-specific odds ratios of EOC for ever compared with never users of oral contraceptives were: serous, 0.56 (95% CI: 0.42, 0.74); mucinous, 1.96 (95% CI: 1.04, 3.68); endometrioid, 0.71 (95% CI: 0.49, 1.03); clear cell, 0.66 (95% CI: 0.31, 1.43); and all EOCs, 0.73 (95% CI: 0.59, 0.90). Prolonged oral contraceptive use reduced EOC risk, with persistent protection up to 25 years after the last use. Ever use of hormone replacement therapy increased EOC risk (odds ratio = 1.41, 95% CI: 1.15, 1.72). Among etiologic hypotheses, the retrograde transportation hypothesis accommodates most epidemiologic findings concerning EOC risk.
Age Factors↗
Hormone replacement therapy and the risk of invasive epithelial ovarian cancer in Swedish women.
BACKGROUND: Estrogen replacement therapy (ERT), which is mainly used to relieve climacteric symptoms, increases a woman's risk for uterine endometrial cancer and epithelial ovarian cancer (EOC). Estrogens are often combined with progestins in hormone replacement therapy (HRT) to reduce the risk of uterine endometrial cancer. Data on the association between HRT including progestins and EOC risk are limited. This nationwide case-control study examined EOC risk in relation to HRT regimens with sequentially added progestins (HRTsp) and continuously added progestins (HRTcp). METHODS: Between 1993 and 1995, we enrolled 655 histologically verified incident case patients with EOC and 3899 randomly selected population controls, all 50-74 years of age. Data on HRT use were collected through mailed questionnaires. Multivariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by the use of unconditional logistic regression. RESULTS: Risks of EOC were elevated among ever users as compared with never users of both ERT (OR = 1.43, 95% CI = 1.02 to 2.00) and HRTsp (OR = 1.54, 95% CI = 1.15 to 2.05); risks were elevated for serous, mucinous, and endometrioid subtypes. For all EOC types combined, the greatest risk increases were seen with hormone use exceeding 10 years. Ever use of HRTcp was not associated with increased EOC risk relative to HRTcp never use (OR = 1.02, 95% CI = 0.73 to 1.43). The risk of EOC was elevated among HRTsp ever users as compared with HRTcp ever users (OR = 1.78, 95% CI = 1.05 to 3.01). ORs for EOC after ever use of low-potency estrogens were 1.18 (95% CI = 0.89 to 1.55) for oral and 1.33 (95% CI = 1.03 to 1.72) for vaginal applications, but no relationship was seen between EOC risk and duration of use. CONCLUSION: Ever users of ERT and HRTsp but not HRTcp may be at increased risk of EOC.
Adenocarcinoma, Clear Cell↗
Molecularly imprinted CEC sorbents: investigations into polymer preparation and electrolyte composition.
The influence of the sorbent preparation protocol and separation parameters on the selectivity and chromatographic efficiency of super-porous molecularly imprinted polymer (MIP) monoliths in capillary electrochromatography (CEC) was studied. Chiral templates were employed and enantiomer separation and resolution were used as measures of imprint selectivity and column efficiency, respectively; the latter was in addition studied by chromatography of non-related aromatic structures. The polymer preparation was varied with respect to monomer composition in the pre-polymerisation mixture and also the use of single versus multiple template(s). The separation parameters investigated were type and content of organic solvent and surfactant modifier in the electrolyte. It was found that acetone and acetonitrile in buffer mixtures provided enantiomer separation of enantiomers of the template and also structural analogues; however, the degree of separation was greatly influenced by the content in the electrolyte. Three surfactants, sodium dodecylsulfate (SDS), cetyltrimethylammonium bromide (CTAB) and polyoxyethylene sorbitanmonolaurate (Tween 20), were examined as electrolyte modifiers. It was found that addition of SDS decreased and CTAB and Tween 20 increased the enantiomer separation. SDS and CTAB could be used up to 1 mM concentration whereas Tween could be used up to 90 mM concentration without causing baseline disturbances. The effects found and demonstrated strongly suggest that these parameters are to be considered during optimisation of an MIP-CEC system.
Journal Article↗
Molecularly imprinted polymers.
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Journal Article↗