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Biomedical subjects

A Vinther

Publications and source records attributed to A Vinther.

12 recordsLinked to original sources
PubMed2006

Exercise-induced rib stress fractures: potential risk factors related to thoracic muscle co-contraction and movement pattern.

The etiology of exercise-induced rib stress fractures (RSFs) in elite rowers is unclear. The purpose of the study was to investigate thoracic muscle activity, movement patterns and muscle strength in elite rowers. Electromyographic (EMG) and 2-D video analysis were performed during ergometer rowing, and isokinetic muscle strength was measured in seven national team rowers with a history of RSF and seven matched controls (C). RSF displayed a higher velocity of the seat in the initial drive phase (RSF: 0.25+/-0.03, 0.25 (0.15-0.33) m/s vs C: 0.15+/-0.06, 0.18 (-0.11-0.29) m/s P=0.028) (Mean+/-SEM, median and range). Further, RSF had greater co-contraction of m. serratus anterior and m. trapezius in the mid-drive phase (RSF: 47.5+/-3.4, 48.5 (35.8-60.2)% EMG signal overlap vs C: 30.8+/-6.5, 27.0 (11.2-61.6)%P=0.043). In addition, the RSF subjects showed a lower knee-extension to elbow-flexion strength ratio (RSF: 4.2+/-0.22, 4.3 (3.5-5.1) vs C: 4.8+/-0.16, 5.0 (4.2-5.3) P=0.043), indicating stronger arms relative to legs compared with controls. In conclusion, increased thoracic muscle co-contraction, altered movement patterns and reduced leg/arm strength ratio were observed in the RSF subjects, which may all predispose toward an increased risk of RSF.

Adult↗
PubMed1999

Managing job strain: a randomized, controlled trial of an intervention conducted by mail and telephone.

A randomized, clinical intervention focused on alleviating job strain was conducted over 6 months by mail and/or telephone with a total of 136 employees of Bank of America. Both the mail and mail plus telephone interventions evidenced positive results, with the mail plus telephone intervention being the more effective. Given the relative low cost of such mediated interventions, the results provide a basis for the further development of interventions that may demonstrate both clinical and cost effectiveness.

Adaptation, Psychological↗
PubMed1996

Improved peptide mapping using phytic acid as ion-pairing buffer additive in capillary electrophoresis.

By digestion of the highly basic polypeptide aprotinin or bovine pancreatic trypsin inhibitor (BPTI) with endoproteinase Lys-C after unfolding, reduction and pyridylethylation, five fragments are obtained. These fragments are separated by free solution capillary electrophoresis using a phosphate buffer at neutral pH. The effect of the ion-pairing buffer additive phytic acid on the separation was investigated. It is shown that phytic acid through ion-pair formation influences the mobility of only those peptide fragments having a net positive charge at the pH of the separation buffer. The affinity of phytic acid to the peptides correlates with their isoelectric point and the charge to mass ratios. Hence, by changing the concentration of phytic acid, it is possible to manipulate the migration order and the separation of the peptides.

Amino Acid Sequence↗
PubMed1996

Synthesis of stereoisomers and isoforms of a tryptic heptapeptide fragment of human growth hormone and analysis by reverse-phase HPLC and capillary electrophoresis.

The amino acid sequence Asn-Gly has at pH 7 a tendency to induce deamidation of asparagine to aspartic acid via the formation of a cyclic imide. This imide opens up to yield Asp-Gly or the isoaspartic acid (isoAsp) form, isoAsp-Gly. Both isomers may be found in their L-form or D-form. Like Asn-Gly, the sequence Asp-Gly has a tendency for isomerization and racemization via the formation of a cyclic imide intermediate. When human growth hormone is digested with trypsin, one of the fragments is a heptapeptide (amino acid residues 128-134) containing the amino acid sequence Asp-Gly (amino acid residues 130 and 131). This heptapeptide, as well as stereoisomers and isoforms where L-Asp was replaced by D-Asp, L-isoAsp, D-isoAsp or the L-cyclic imide, respectively, has been synthesized and used as a standard to achieve separation of the five forms by capillary electrophoresis and by reverse-phase HPLC. Capillary electrophoresis analysis was performed in uncoated capillaries by the use of aspartic acid/cyclodextrin buffers at low pH. The elution order of the aspartic-acid-containing heptapeptides was D-Asp, L-Asp, L-isoAsp, D-isoAsp and L-cyclic imide. Reverse-phase HPLC analysis was performed on a C18 column by the use of a shallow acetonitrile gradient in trifluoroacetic acid/water. The elution order was D-isoasp, L-isoASp, L-Asp, D-Asp and L-cyclic imide. Human growth hormone samples were degraded by incubation at high temperature and analyzed for their potential content of isomerization and racemization products. Only L-forms of aspartic acid and isoaspartic acid of the heptapeptide fragment were found.

Amino Acid Sequence↗
PubMed1995

Effective ion-pairing for the separation of basic proteins in capillary electrophoresis.

The addition of the sodium salt of phytic acid to the separation buffer (pH's 6.0-9.5) has allowed the analysis of a number of basic proteins (pI's > 9) by capillary electrophoresis. The method of analysis is simple and leads to considerable improvement in peak shape. Some very basic proteins, totally adsorbed onto the capillary fused silica surfaces in the presence of buffer only, can be analysed as sharp signals when this polyanionic species is included in the running electrolyte. These improvements in analysis are thought to arise as a result of the suppression of coulombic interactions between these positively charged proteins (ion-paired to phytic acid) and the negatively charged silanol groups on the inner wall of the capillary.

Adsorption↗
PubMed1992

Capillary electrophoretic determination of the protease Savinase in cultivation broth.

The highly basic washing enzyme Savinase and various analogues were analysed by micellar electrokinetic chromatography (MEKC) and electrophoresis. Broth samples were withdrawn during the cultivation of Savinase by recombinant microorganisms. Savinase peak areas obtained by MEKC-electrophoretic analysis were normalized with respect to migration time and compared with traditional enzyme activity measurements. The electropherograms indicated thermal degradation of the Savinase molecule at high field strengths. Baseline separation of Savinase and two analogues was achieved.

Bacillus↗
PubMed1990

Identification of aprotinin degradation products by the use of high-performance capillary electrophoresis, high-pressure liquid chromatography and mass spectrometry.

A preparation of bovine aprotinin, bovine pancreatic trypsin inhibitor, was subjected to high-performance capillary electrophoresis (HPCE) analysis and the purity was calculated to be approximately 80%. The two dominating contaminants were integrated to approximately 7% each as compared to the intact molecule. Characterization by high-pressure liquid chromatographic (HPLC) and mass spectrometric analysis was carried out on digests of the reduced and alkylated molecules. The contaminants were identified as truncated aprotinin, missing one and two amino acids, respectively, at the C-terminus. No such structures were identified in similar amounts in preparations of recombinant aprotinin by HPLC or HPCE.

Animals↗
PubMedDate not supplied

Using capillary electrophoresis in the optimization of a carboxypeptidase Y catalyzed transpeptidation reaction.

A peptide amide, R-Arg-NH2, was produced by carboxypeptidase Y (CPDY)-catalyzed transpeptidation of a peptide, R-Ala-OH in presence of a large excess of Arg-NH2. Baseline separation of R-Ala-OH and R-Arg-NH2 was achieved by free solution capillary electrophoresis (CE) analysis. With CE the reactions could be closely followed with an analysis frequency of 3-6 h-1. Due to a low consumption of sample per CE analysis (1-5 nL introduced, 5-6 microL in the sample vial), the reactions were performed in 100 and 250 microL volumes. Consequently, the optimization experiments consumed limited amounts of enzyme and substrate only. At optimized experimental conditions approximately 90% conversion of the starting peptide, R-Ala-OH, to R-Arg-NH2 was achieved.

Amino Acid Sequence↗