Structural Macrokinetics of Biomimetic Processes in Artificial Cells

It is known that all cytophysiological processes occur on the cell ultrastructure, which is a heterogeneous (heterophase) medium. So the kinetics of metabolic processes should be considered as a structural macrokinetics of this partially ordered medium (soft matter). Our model reproduces the structural-macrokinetic aspect of a number of metabolic phenomena, based on the physico-chemical analogies with the biological cell. Thus, the semipermeability of bioorganic membranes is simulated by semiconductive polymer inorganic dynamic membranes, exergonic chemoosmotic redox processes are equivalent to cellular respiration, biomimetic self-oscillating reactions are analogues of oscillatory metabolic processes and finally the structure formation in these models is also provided by reaction-diffusion mechanisms.

Structural Macrokinetics of Biomimetic Processes in Artificial Cells

It is known that all cytophysiological processes occur on the cell ultrastructure, which is a heterogeneous (heterophase) medium. So the kinetics of metabolic processes should be considered as a structural macrokinetics of this partially ordered medium (soft matter). Our model reproduces the structural-macrokinetic aspect of a number of metabolic phenomena, based on the physico-chemical analogies with the biological cell. Thus, the semipermeability of bioorganic membranes is simulated by semiconductive polymer inorganic dynamic membranes, exergonic chemoosmotic redox processes are equivalent to cellular respiration, biomimetic self-oscillating reactions are analogues of oscillatory metabolic processes and finally the structure formation in these models is also provided by reaction-diffusion mechanisms.

PET Tracers for Clinical Imaging of Breast Cancer

Molecular imaging of breast cancer has undoubtedly permitted a substantial development of the overall diagnostic accuracy of this malignancy in the last years. Accurate tumour staging, design of individually suited therapies, response evaluation, early detection of recurrence and distant lesions have also evolved in parallel with the development of novel molecular imaging approaches. In this context, positron emission tomography (PET) can be probably seen as the most interesting molecular imaging technology with straightforward clinical application for such purposes. Dozens of radiotracers for PET imaging of breast cancer have been tested in laboratory animals. However, in this review we shall focus mainly in the smaller group of PET radiopharmaceuticals that have lead through into the clinical setting. PET imaging can be used to target general metabolic phenomena related to tumoural transformation, including glucose metabolism and cell proliferation, but can also be directed to specific hormone receptors that are characteristic of the breast cancer cell. Many other receptors and transport molecules present in the tumour cells could also be of interest for imaging. Furthermore, molecules related with the tumour microenvironment, tumour induced angiogenesis or even hypoxia could also be used as molecular biomarkers for breast cancer imaging.

Intranuclear membranous inclusions in oocytes of a viviparous teleost (Xiphophorus helleri)

Intranuclear inclusions were observed in oocytes of Xiphophorus helleri during prophase I. In osmium-fixed leptotene nuclei, the inclusions were made up of groups of membrane-limited vesicles or tubules with pale contents, situated near the inner nuclear membrane with which some of them exhibited apparent continuities. In zygotene nuclei, larger vesicles also appeared bounded by two or three membranes and containing tubules apparently invaginated from their walls. In pachytene-dictyate nuclei most vesicular bodies had a wall formed by stratified membranes, or were entirely made up of membranous whorls. In glutaraldehyde-osmium fixed material some of these myeline-like bodies showed a peculiar arrangement, consisting of concentric bands each containing thick inner dense lamellae 2-0-3-0 nm thick and a 5-0 nm outer lamella. It is suggested that these inclusion bodies arise from the inner nuclear membrane of oocytes when cells start to grow intensely during prophase I. The bodies seem to become more complex at late prophase, probably by association of individual vesicles and the occurrence of multiple membrane invaginations, which may be related to active metabolic phenomena taking place at this stage in oocytes.