Comparative in vivo mucoadhesion studies of thiomer formulations using magnetic resonance imaging and fluorescence detection.

The aim of this study was to compare different oral delivery systems based on the thiolated polymer polycarbophil-cysteine (PCP-Cys) and to provide evidence for the validity of the hypothesis that unhydrated polymers provide better mucoadhesion in vivo. To achieve dry polymer application, a new, experimental dosage form named Eutex (made of Eudragit L100-55 and latex) capsule has been developed. Magnetic resonance imaging was used to localize the point of release of the thiolated polymer from the application forms via the positive magnetic resonance signal from a gadolinium complex (Gd-DTPA). In vivo mucoadhesion was determined by ascertaining the residence time of the fluorescence-tagged thiomer on intestinal mucosa after 3 h. Results showed that in comparison to conventional application forms the Eutex capsules led to 1.9-fold higher mucoadhesive properties of PCP-Cys when compared to application with a conventional enteric-coated capsule, and to 1.4-fold higher mucoadhesion when compared to administration with an enteric-coated tablet of the thiomer. The findings of this study should contribute to the understanding of mucoadhesion and mucoadhesion influencing parameters in vivo and should therefore be of considerable interest for the development of future mucoadhesive oral drug delivery dosage forms.

[Hybrid operation theatre in vascular surgery. Options and perspectives]. / Hybridoperationssaal in der Gefäßchirurgie. Möglichkeiten und Perspektiven.

BACKGROUND: Demographic development leads to an increase in vascular interventions due to the increase in elderly and multimorbid patients. The aim of this study was to demonstrate the open interventional therapy options and their influence on staff and patients which have become possible due to the introduction of angio-hybrid operations including 3-D imaging Dyna-CT. MATERIAL AND METHODS: The modifications with respect to radiation protection for staff, improvements for patients and the possibilities of operative 3-D imaging Dyna-CT are described based on the current literature. RESULTS: The implementation of angio-hybrid operation theaters has resulted in new open interventional treatment options which can also be employed for high risk elderly patients with aortic and peripheral arterial pathologies. With hybrid operations the radiation exposure and contrast medium exposure can be reduced for patients and an improvement in the results can also be achieved. The implementation of 3-D imaging in the angio-hybrid operation theater could also lead to further improvements, especially for complex aortic procedures. DISCUSSION: Using angio-hybrid operational procedures complex interventions can be carried out with more safety for patients and personnel. The implementation of 3-D imaging Dyna-CT offers additional interesting options for complex aortic procedures.

In vivo investigation of thiomer-polyvinylpyrrolidon nanoparticles using magnetic resonance imaging.

This study focused on the investigation of the permeation enhancing effects of a stomach targeted, nanoparticulate drug delivery system. The polyacrylic acid-cysteine/polyvinylpyrrolidon nanoparticles were loaded with the magnetic resonance imaging (MRI) contrast agent diethylenetriaminepentaacetic acid gadolinium(III)dihydrogen salt (Gd-DTPA). Average particle size was determined to be 130 nm and the optimum for stability was found to be below a pH of 4.5. In vitro permeation studies were performed on rat gastric mucosa and revealed an eightfold increase in Gd-DTPA uptake when incorporated in the nanoparticles compared to evaluation in the presence of unformulated polyacrylic acid-cysteine. In vivo investigations with rats were performed via the noninvasive MRI method in order to track the nanoparticles way through the gastrointestinal tract. When Gd-DTPA was administered orally as nanoparticulate suspension, an increased MRI signal in the urinary bladder was detected after 34 min, providing evidence for systemic uptake and renal elimination of the contrast agent. As control experiments with Gd-DTPA only or in combination with unformulated polyacrylic acid-cysteine revealed no MRI signal increase at all, the significant permeation enhancing effect could be identified based on the nanoparticulate formulation.

A new model of active avoidance conditioning adequate for pharmacological studies.

A model of rapid learning (active avoidance conditioning), using rats, is described which induces retention depending on the number of trials to which the animals are submitted. For 3 trials (double stimulation) adequately spaced, the memory trace lasts for 48 hr, whilst 6 trails induce a trace for 10 days. One single application of the double stimulation does not give any apparent retention in normal rats for 24 hr. This experimental fact is used to study and screen the activity of substances on the learning process. Animals treated with piracetam, pemoline, methamphetamin, strychnine, pyritinol and meclofenoxate before this single trial, display evidence of retention 24 hr later. Other substances, with known clinical CNS activites, eg, tranquillizers, analgesics, etc... show no positive effect on the mnesic trace.

Nootropic drugs and aging.

Nootropics are drugs which ameliorate the functional "plasticity" of the central nervous system. The nootropic drug acts at the telencephalic level through a series of bioenergetic, hemorheological, microcirculatory and neurochemical mechanisms. As to this, recent data show a facilitation by piracetam, of the efficiency of the central cholinergic system.