Biomedical subjects

D Bylund

Publications and source records attributed to D Bylund.

8 recordsLinked to original sources

PubMed2005

Bio fuel ash in a road construction: impact on soil solution chemistry.

Limited natural resources and landfill space, as well as increasing amounts of ash produced from incineration of bio fuel and municipal solid waste, have created a demand for useful applications of ash, of which road construction is one application. Along national road 90, situated about 20 km west of Sollefteå in the middle of Sweden, an experiment road was constructed with a 40 cm bio fuel ash layer. The environmental impact of the ash layer was evaluated from soil solutions obtained by centrifugation of soil samples taken on four occasions during 2001-2003. Soil samples were taken in the ash layer, below the ash layer at two depths in the road and in the ditch. In the soil solutions, pH, conductivity, dissolved organic carbon (DOC) and the total concentration of cations (metals) and anions were determined. Two years after the application of the ash layers in the test road, the concentrations in the ash layer of K, SO4, Zn, and Hg had increased significantly while the concentration of Se, Mo and Cd had decreased significantly. Below the ash layer in the road an initial increase of pH was observed and the concentrations of K, SO4, Se, Mo and Cd increased significantly, while the concentrations of Cu and Hg decreased significantly in the road and also in the ditch. Cd was the element showing a potential risk of contamination of the groundwater. The concentrations of Ca in the ash layer indicated an ongoing hardening, which is important for the leaching rate and the strength of the road construction.

Anions↗

PubMed2003

Phosphate buffers in capillary electrophoresis/mass spectrometry using atmospheric pressure photoionization and electrospray ionization.

Capillary electrophoresis (CE) has been combined with atmospheric pressure photoionization (APPI) and electrospray ionization (ESI) for mass spectrometric (MS) detection. Separation conditions using potassium phosphate buffer and ammonium formate buffer have been compared for analysis of eleven pharmaceutical bases. The results showed improvements in separation efficiency and peak symmetry when phosphate buffer was used. The low flow in CE may enable utilization of these advances with MS detection. Compared with ESI, the APPI technique provided a cluster-free background. The enhanced signal-to-noise ratio in the total ion current (TIC) and the reduced spectral background indicated that the APPI process is less affected by non-volatile salts in the CE buffers. This results in a wider range of choice of CE buffers in CE/MS analysis when APPI is the ionization method.

Journal Article↗

PubMed2001

Peak purity assessment in liquid chromatography-mass spectrometry.

Fixed-size moving window evolving factor analysis and base peak chromatograms have been used for peak purity detection in data generated with LC-MS. The two methods were evaluated with both real and simulated data and were found to be fast and complementary to each other. When a possibly impure peak is detected, it is suggested that further information can be obtained from local principal component analysis modelling and comparative mass chromatogram plots.

Chromatography, Liquid↗

PubMed2001

A method for determination of ion distribution within electrosprayed droplets.

A simplified method for determination of ion distribution within electrospray ionization droplets has been developed. The method is based on an electrospray ionization mass spectrometry equilibrium partitioning model recently developed by Enke (Enke, C. G. Anal. Chem. 1997, 69, 4885-4893). This "simple" method required only two samples to be analyzed at each solution composition compared to the method previously reported. Furthermore, as the same m/z value is monitored in both experiments, possible effects of the mass-dependent ion transmission in the quadrupole were eliminated. Tetra-alkylammonium compounds with variable hydrophobicity were used as model compounds and the effect of methanol-water composition in the electrosprayed solution was studied. It was found, as expected, that the signal optimized at a high content of methanol in the electrosprayed solution. The distribution coefficient for analyte ions between the droplet surface and bulk solution maximize, however, at a lower content of methanol in the electrosprayed solution.

Journal Article↗

PubMed1995

Apolipoprotein E genotyping methods for the clinical laboratory.

To select the best method for detecting apolipoprotein E (apo E) genotypes determined by the three common alleles epsilon 2, epsilon 3 and epsilon 4, we compared the radiolabeled allele-specific oligonucleotide (ASO) probe assay and the nonisotopic restriction isotyping assay. Leukocytic DNA was extracted from the blood of 93 patients after which the region containing two mutation points coding amino acid residues 112 and 158 was amplified by using the polymerase chain reaction (PCR). Amplified DNA fragments were spotted on nylon membranes, then hybridized for the ASO probe assay. The amplified DNA fragments were also digested with restriction endonuclease Hhal, followed by polyacrylamide gel electrophoresis for the restriction isotyping assay. The apo E genotypes determined by both methods for every specimen studied were in complete agreement. Although the radiolabeled ASO probe method was 10 times more sensitive than restriction isotyping on polyacrylamide gel, the two were comparable in accuracy. Additionally, because it is simpler to perform, is less time consuming, and is less expensive, we conclude that the restriction isotyping assay is the more suitable of these two methods for use in a clinical laboratory.

Adolescent↗

PubMed1995

Anticoagulant response to activated protein C: method validation and assay comparison.

Poor anticoagulant response to activated protein C (APC), present in 20-60% of thrombophilic patients, is most often caused by abnormal factor Va due to the mutation of Arg506 to Gln, and DNA sequencing confirms this finding. At Scripps Reference Laboratory (SRL), we have validated an in-house assay to detect APC resistance. A study of 80 normal subjects (40 males and 40 females, 21-60 years old) showed that adult males and females have statistically significant differences in their anticoagulant response to APC. Furthermore, APC response is increased in older individuals. APC responses of the same 80 normal samples determined using the SRL assay were compared to a commercial kit (Chromogenix, Coatest). Although both procedures are similar, the SRL assay gave a greater difference between male and female normal ranges. Eight of 18 (44%) thrombophilic patients were identified as APC-resistant. Samples from individuals having the factor V Arg506Gln mutation yielded low responses to APC in both assays. Determination of APC resistance assists physicians in determining the cause of thrombotic disorders and may eventually help in predicting the risk of familial thrombosis.

Adult↗

PubMed1994

Mohs micrographic excision of sebaceous carcinoma of the eyelids.

BACKGROUND: Sebaceous carcinoma of the eyelid is a difficult tumor to manage because of diagnostic difficulties and pagetoid-type spread in the conjunctivae. OBJECTIVE: We report our experience with eight patients using the Mohs technique of excision with reconstruction. METHODS: Six cases were managed with paraffin-embedded hematoxylin and eosin sections. One case was managed by frozen histologic sections and one was managed with frozen section processing followed by paraffin-embedded section review. RESULTS: The correct pathologic diagnosis was made initially in only 50% of the cases. Eighty-eight percent of the cases revealed intraepithelial neoplasm. There has been one recurrence with metastatic disease. The average follow-up period has been 56.8 months. CONCLUSIONS: We advocate early recognition and excision with the Mohs technique with paraffin-embedded sections followed by reconstruction. The use of paraffin-embedded histologic sections helps with interpretation of intraepithelial and pagetoid tumor spread.

Adenocarcinoma, Sebaceous↗

PubMed1982

Sensitization produced by repeated administration of naloxone is blocked by food deprivation.

The current study was conducted in order to explore the effects of repeated naloxone administration as a function of food intake. Rats were trained to press a bar to avoid foot-shock. They were allowed either free or restricted access to food. Free-feeding rats developed a strong sensitivity to naloxone, as manifested by an increased shock rate after naloxone injection. When animals were food-deprived, the sensitivity was greatly reduced. A different species (mouse) and two different tests were used to examine further the effects of food intake and pretreatment with naloxone. The mice were given either free access to food or a restricted diet and were pretreated with either naloxone or saline. The effects of food intake and pretreatment with naloxone were examined in terms of motor activity, morphine analgesia and naloxone hyperalgesia. The results showed that prior exposure to naloxone in free-feeding animals enhanced the suppressant effect of naloxone on motor activity and the analgesic effects of morphine (as measured by paw-lick, but not as measured by jump in the hot-plate test), but had no effect on the hyperalgesic effect of naloxone. When mice were food-deprived during naloxone administration, sensitization did not occur. The hypothesis that naloxone sensitivity is due to changes in the number of brain opiate receptors was tested by measuring the number and affinity of [3H]naloxone binding sites on brain membranes from mice chronically treated with naloxone. Neither naloxone pretreatment nor food deprivation affected the number or affinity of binding sites. The gamma-aminobutyric acid antagonist effect of naloxone (as measured by gamma-[3H]aminobutyric acid binding) was also unchanged by naloxone pretreatment. Thus, the basis of the interactions between naloxone and the feeding state remains unclear.

Animals↗