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Biomedical subjects

P Gründler

Publications and source records attributed to P Gründler.

8 recordsLinked to original sources
PubMed2005

Association interaction and voltammetric determination of 1-aminopyrene and 1-hydroxypyrene at cyclodextrin and DNA based electrochemical sensors.

The aim of this work was voltammetric determination of 1-aminopyrene and 1-hydroxypyrene using carbon paste electrodes modified with cyclodextrin derivatives and double stranded deoxyribonucleic acid (dsDNA). The detection schemes based on a preconcentration and differential pulse voltammetric (DPV) determination at beta-cyclodextrin and gamma-cyclodextrin modified carbon paste electrode (beta-CD/CPE, gamma-CD/CPE), neutral beta-cyclodextrin polymer and carboxymethyl-beta-cyclodextrin polymer modified screen-printed electrode (beta-CDP/SPE, beta-CDPA/SPE) and dsDNA modified screen-printed electrode (DNA/SPE) are proposed for the trace determination of studied analytes within the concentration range from 2 x 10(-8) to 4 x 10(-7) mol dm(-3) and from 2 x 10(-7) to 4 x 10(-6) mol dm(-3) with the limits of quantification down to 10(-8) mol dm(-3). Depending on pH, 1-aminopyrene interacts with both surface attached CD and DNA by electrostatic bonds and supramolecular complexation while 1-hydroxypyrene associates with the CD hosts via complexation. The 1-aminopyrene interaction with dsDNA was confirmed by fluorimetric measurements in the solution phase using a competing DNA-TO-PRO-3 dye complex. In addition, the effect of temperature on this association was investigated using an electrically heated DNA-modified carbon paste electrode (DNA/CPE).

Biosensing Techniques↗
PubMed2000

Stripping analysis of nucleic acids at a heated carbon paste electrode.

A new electrically heated carbon paste electrode has been developed for performing adsorptive stripping measurements of trace nucleic acids. Such coupling of electrochemistry at electrically heated electrodes with adsorptive constant-current stripping chronopotentiometry offers distinct advantages for trace measurements of nucleic acids. The application of increased temperatures during the deposition step results in dramatic (4-34-fold, depending on temperature applied) enhancement of the stripping signal. Such improvement is attributed to the accumulation step at the heated electrode. Forced thermal convection near the electrode surface facilitates the use of quiescent solutions and hence of ultrasmall volumes. Using an electrode temperature of 32 degrees C and a quiescent solution during the 1-min accumulation, the response is linear over the 1-8 mg/L range tested, with a detection limit of 0.5 mg/L. Such electrode heating technology offers great promise for various applications involving thermal manipulations of nucleic acids.

Carbon↗
PubMed2000

Basics of temperature pulse voltammetry.

A new electrochemical technique is presented that allows peak-shaped voltammograms to be recorded at local temperature values from room temperature to above boiling point. This new method, temperature pulse voltammetry (TPV), is analogous to differential pulse voltammetry (DPV), but makes use of temperature jumps instead of potential pulses. Fundamentals are presented and potentialities demonstrated. As an example, ferrocyanide is investigated using a new kind of heated electrode on the basis of screen-printed gold layer structures on low-temperature cofired ceramics (LTCC) substrates.

Journal Article↗
PubMed2000

Phenomena at hot-wire electrodes.

An overview is given describing phenomena at heated microelectrodes where matter and heat energy are simultaneously emitted into the solution. With controlled electric heating, virtual "quiescent" periods as well as ones with constant streaming conditions are found that depend on the heating time. A close look at a permanently heated wire reveals a well defined structure with stationary concentration, temperature and flow rate profiles. The observed phenomena can be utilised for analytical measurements, e.g. with the novel method "Temperature Pulse Voltammetry" (TPV).

DNA↗
PubMed1999

Electrochemical behaviour of cytochrome c at electrically heated microelectrodes.

The structural changes in cytochrome c with temperature have been been followed using a recently developed electrically-heated microelectrode sensor. Differential pulse voltammetry was used to perform electrochemical measurements of cytochrome c oxidation at different temperatures at heated bare gold electrodes contained in phosphate-buffered cytochrome c solution at room temperature. The voltammetric response shows the onset of unfolding and a marked dependence of the signal on electrode temperature. This augurs well for applications of heated electrodes as local probes in the study of the temperature dependence of electron transfer processes of other redox proteins, avoiding problems of bulk deterioration.

Animals↗
PubMed1987

Intestinal toxicoinfection by Clostridium botulinum type F in an adult. Case associated with Guillain-Barré syndrome.

A 27-year-old man with type F botulism (classification undetermined) had two episodes of botulinum toxaemia with identification of botulinum toxin and Clostridium botulinum organisms in faecal specimens during a three-month stay in hospital. Between these clinical episodes neither toxin nor Cl botulinum could be demonstrated. The illness was severe with quadriplegia, respiratory insufficiency, and bowel paralysis. In addition the patient had sensory abnormalities and a raised protein in the cerebrospinal fluid. The results demonstrate for the first time in detail an intestinal colonisation with and multiplication of C botulinum organisms and in-vivo production of toxin in an adult. The clinical findings at first pointed to Guillain-Barré syndrome, and it is suggested that patients with this syndrome should be examined for botulinum toxin in serum and for toxin and organisms in stool.

Adult↗
PubMed1987

A neutralizing epitope on human rhinovirus type 2 includes amino acid residues between 153 and 164 of virus capsid protein VP2.

Use has been made of a monoclonal antibody (designated 8F5) to map a neutralizing epitope on the viral capsid protein VP2 of human rhinovirus 2 (HRV2). This antibody which was raised against the native virus, neutralizes HRV2 and is also capable of recognizing denatured VP2 on Western blots. To examine the binding site of 8F5, VP2 of HRV2 was expressed in Escherichia coli. Deletions starting at the 3' end were then introduced into the gene for VP2 using Bal-31 nuclease. Polypeptides shortened at the carboxy terminus of VP2 were obtained from the deletions and were blotted onto nitrocellulose. The samples were then probed with monoclonal antibody 8F5. Recognition by 8F5 was maintained as long as the expressed polypeptide contained the VP2 sequence up to amino acid 164 or beyond. However, when the VP2 sequence was truncated to amino acid 153 or less 8F5 was no longer able to bind. The neutralization epitope (or part of it) recognized by 8F5 on VP2 is therefore located between amino acids 153 and 164.

Amino Acid Sequence↗