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Biomedical subjects

Jens Burmeister

Publications and source records attributed to Jens Burmeister.

6 recordsLinked to original sources
PubMed2004

Online resistance monitoring during autometallographic enhancement of colloidal Au labels for DNA analysis.

DNA diagnostics at the point-of-care requires biosensors that rely on highly sensitive transducers and are producible at low cost. A promising candidate technology is based on direct electrical detection of autometallographically enhanced Au labeled analytes. We present a substantial improvement to the previously used method by introducing online DC resistance monitoring during the autometallographic enhancement process. Since multi-step enhancement, washing, drying, and measurement cycles are eliminated, our method takes the direct electrical detection method a step further to applicability in a point-of-care environment. The feasibility of the novel method is demonstrated by its application in a simple DNA hybridization assay and the analysis of a single nucleotide polymorphism (SNP) using allele-specific hybridization. Unequivocal discrimination of all possible base pairing combinations in the SNP assay has been achieved. The SNP assay in particular indicates the potential of the method for analyte quantification.

Biosensing Techniques↗
PubMed2004

Single nucleotide polymorphism analysis by chip-based hybridization and direct current electrical detection of gold-labeled DNA.

Single nucleotide polymorphism (SNP) analysis at the point of care requires a low cost detection technology that is capable of miniaturization, multiplexing, and high sensitivity. Direct current electrical detection (DCED) of DNA following nanoparticle labeling and silver enhancement is a promising candidate technology for point-of-care diagnostics. In this work we present, for the first time, SNP analysis in PCR products from patient samples using DCED, taking this platform technology a step closer to practical application. We developed a silane functionalized polymer for coating of biochip surfaces. This polymeric coating is stable under harsh conditions and has exceptionally high binding capacity. Allele-specific oligonucleotide probes were immobilized on chips coated with this polymer. Biotinylated PCR products of the human cholesteryl ester transfer protein gene from different patients were hybridized to the chips, labeled with gold nanoparticles, and autometallographically enhanced. The chips were scanned for DC electrical resistance by applying movable electrodes to the surface. Eighteen of nineteen patient samples were assigned the correct genotype. Our results demonstrate that SNP analysis of patient samples is feasible with DCED.

Affinity Labels↗
PubMed2002

In vivo properties of an anti-GnRH Spiegelmer: an example of an oligonucleotide-based therapeutic substance class.

Spiegelmers are high-affinity l-enantiomeric oligonucleotide ligands that display high resistance to enzymatic degradation compared with d-oligonucleotides. The target binding properties of Spiegelmers can be designed by an in vitro-selection process starting from a random pool of oligonucleotides. Applying this method, a Spiegelmer with high affinity (K(D) = 20 nM) for the peptide hormone, gonadotropin-releasing hormone (GnRH) was isolated. The Spiegelmer acts as an antagonist to GnRH in Chinese hamster ovary cells stably expressing the human GnRH receptor, and its activity is unchanged by linking to 40-kDa polyethylene glycol. In a castrated rat model the Spiegelmer further demonstrated strong GnRH antagonist activity, which is more pronounced and persists longer with the polyethylene glycol-linked derivative. Furthermore, in rabbits the anti-GnRH Spiegelmer was shown to have a very low, possibly negligible immunogenic potential. These studies suggest that Spiegelmers could be of substantial interest in the development of new pharmaceutical approaches against GnRH and other targets.

Animals↗
PubMed2002

GnRH binding RNA and DNA Spiegelmers: a novel approach toward GnRH antagonism.

Mirror-image oligonucleotide ligands (Spiegelmers) that bind to the pharmacologically relevant target gonadotropin-releasing hormone I (GnRH) with high affinity and high specificity have been identified using the Spiegelmer technology. GnRH is a decapeptide that plays an important role in mammalian reproduction and sexual maturation and is associated with several benign and malignant diseases. First, aptamers that bind to D-GnRH with dissociation constants of 50-100 nM were isolated out of RNA and DNA libraries. The respective enantiomers of the DNA and RNA aptamers were synthesized, and their binding to L-GnRH was shown. These Spiegelmers bind to L-GnRH with similar affinity to that of the corresponding aptamers that bind to D-GnRH. We further demonstrated dose-dependent inhibition of GnRH-induced Ca(2+) release in Chinese hamster ovary cells that were stably transfected with the human GnRH receptor.

Animals↗
PubMed2002

Auxological computer based network for early detection of disorders of growth and weight attainment.

INTRODUCTION: For several years practising pediatricians and pediatric endocrinologists in Leipzig have been collaborating closely to achieve early detection of growth disorders. As a result of this collaboration a data-bank was established in September 1998 into which height and weight measurements were entered and related to age and gender. This well established network of pediatricians in practice, pediatric endocrinologists and the auxological data-bank functions well. METHODS: All data are anonymized and continually monitored. By September 2000, the data for 60,984 children had been assessed. The data were evaluated using the German Synthethic Norm Curve for body height and German normal data for BMI. Pathology of growth dynamics was assumed when change in height SDS was greater than 0.5 height SDS/year. RESULTS: Analysis showed that 2,216 children (3.6%) had a height greater than the 97th percentile and 2,775 children (4.5%) had a height less than the 3rd percentile of the normative reference. BMI above the 97th percentile was found in 7,687 children (12.6%) and below the 3rd percentile in 2,678 children (4.4%). When assessing growth development (n = 5,665), 194 (3.4%) showed acceleration and 155 (2.7%) showed deceleration of growth. CONCLUSION: The computer-based monitoring system is useful to document short-term and long-term changes of growth and weight attainment in the general population. The presence of growth disorders and/or disturbed weight gain can be detected early in the individual child.

Body Height↗