Polymeric complements to the Alzheimer's disease biomarker ß-amyloid isoforms Aß1-40 and Aß1-42 for blood serum analysis under denaturing conditions.

Treatment of Alzheimer's disease (AD) is plagued by a lack of practical and reliable methods allowing early diagnosis of the disease. We here demonstrate that robust receptors prepared by molecular imprinting successfully address current limitations of biologically derived receptors in displaying affinity for hydrophobic peptide biomarkers for AD under denaturing conditions. C-terminal epitope-imprinted polymers showing enhanced binding affinity for Aß1-42 were first identified from a 96-polymer combinatorial library. This information was then used to synthesize molecularly imprinted polymers for both of the ß-amyloid (Aß) isoforms and a corresponding nonimprinted polymer. A solid-phase extraction method was developed to be compatible with sample loading under conditions of complete protein denaturation. This resulted in a method capable of quantitatively and selectively enriching a shorter C-terminal peptide corresponding to the sequences Aß33-40 and Aß33-42 as well as the full-length sequence Aß1-40 and Aß1-42 from a 4 M guanidinum chloride solution. Application of the method to serum allowed selective, high-recovery extraction of both biomarkers at spiking levels marginally higher than clinically relevant concentrations found in cerebrospinal fluid.

Dental Care of Patients With Dementia: A Survey on Practice Equipment, Training, and Dental Treatment.

For patients with dementia, dental care can pose a considerable challenge due to cognitive impairment, behavioral, and psychological symptoms, and (often subsequently) limited autonomous oral care. In this study, we aimed to assess the proficiency of dentists in general practice in the outpatient dental care of these patients. A total of 119 dentists from private practices in Lower Saxony, Germany, participated in this study. Concerning treatment of patients with dementia, they provided details about (1) practice equipment/consultation, (2) training/expertise, and (3) special circumstances of dental treatment. Participating dentists predominantly reported to use medical aids (e.g., positioning cushions) to improve the treatment situation for patients with dementia. Over two thirds (68.6%) offered consultations in nursing homes, and at the patients' homes (47.0%). The training rate was remarkably low in the field of gerodontology for dentists and their practice staff (<10%), however, 54.5% expressed interest in such training. The majority of dentists reportedly adapted their treatment strategy to the needs of patients with dementia (e.g., communication, inclusion of caregivers, time management). Furthermore, most participants adapted dental treatment adequately (e.g., strict indication for tooth extraction, simple design of dental prostheses). In summary, even though training in the field of gerodontology must be considered insufficient, most dentists in this study showed an adequate adaptation of their treatment strategy as well as consideration of dental characteristics in patients with dementia, along with interest in trainings. We conclude that dementia-specific training should be expanded in the field of dentistry, preferably already at university level.

Microchip electrophoresis profiling of Aß peptides in the cerebrospinal fluid of patients with Alzheimer's disease.

The preferential aggregation of Aß1-42 in amyloid plaques is one of the major neuropathological events in Alzheimer's disease. This is accompanied by a relative reduction of the concentration of Aß1-42 in the cerebrospinal fluid (CSF) of patients developing the signs of Alzheimer's disease. Here, we describe a microchip gel electrophoresis method in polydimethylsiloxane (PDMS) chip that enables rapid profiling of major Aß peptides in cerebrospinal fluid. To control the electroosmotic flow (EOF) in the PDMS channel and also to reduce the adsorption of the peptides to the surface of the channel, a new double coating using poly(dimethylacrylamide-co-allyl glycidyl ether) (PDMA-AGE) and methylcellulose-Tween-20 was developed. With this method, separation of five synthetic Aß peptides (Aß1-37, Aß1-38, Aß1-39, Aß1-40, and Aß1-42) was achieved, and relative abundance of Aß1-42 to Aß1-37 could be calculated in different standard mixtures. We applied our method for profiling of Aß peptides in CSF samples from nonAlzheimer patients and patients with Alzheimer's disease. Aß peptides in the CSF samples were captured and concentrated using a microfluidic system in which magnetic beads coated with anti-Aß were self-organized into an affinity microcolumn under the a permanent magnetic field. Finally, we could detect two Aß peptides (Aß1-40 and Aß1-42) in the CSF samples.

A quantitative CE method to analyse tau protein isoforms using coated fused silica capillaries.

We evaluated the potential of CE to analyse different isoforms of unphosphorylated recombinant tau protein and for separating one phosphorylated tau from the respective unphosphorylated protein. Different capillary coatings such as polyacrylamide, poly-(ethylene oxide) and polybrene (PB) were evaluated to overcome the poor efficiencies obtained with fused-silica capillary. Although peak asymmetry values were quite similar for the three investigated coatings, the peak efficiencies were 35-fold and 5-fold higher with PB coating than with polyacrylamide and poly(ethylene oxide) coatings, respectively. The recovery percentage (over 97%) was satisfactory and confirmed the efficacy of PB coating to limit the adsorption of tau protein to capillary walls. Moreover, PB coating produced higher repeatability for migration times (RSD values <1.2%) in comparison to the neutral coatings. The potential of PB-modified capillary in producing high resolutive separations of one phosphorylated tau isoform from its unphosphorylated counterpart and of a mixture of phosphorylated and unphosphorylated tau peptides was demonstrated with 50 mM phosphate buffer pH 3.0. The separation of unphosphorylated tau isoform 352 (Tau-352) from Tau-352 phosphorylated in vitro by the mitogen-activated protein kinase ERK2, was accomplished in less than 15 min.