The vascular endothelium, a monolayer of endothelial cells (EC), constitutes the inner cellular lining of arteries, veins and capillaries and therefore is in direct contact with the components and cells of blood. The endothelium is not only a mere barrier between blood and tissues but also an endocrine organ. It actively controls the degree of vascular relaxation and constriction, and the extravasation of solutes, fluid, macromolecules and hormones, as well as that of platelets and blood cells. Through control of vascular tone, EC regulate the regional blood flow. They also direct inflammatory cells to foreign materials, areas in need of repair or defense against infections. In addition, EC are important in controlling blood fluidity, platelet adhesion and aggregation, leukocyte activation, adhesion, and transmigration. They also tightly keep the balance between coagulation and fibrinolysis and play a major role in the regulation of immune responses, inflammation and angiogenesis. To fulfill these different tasks, EC are heterogeneous and perform distinctly in the various organs and along the vascular tree. Important morphological, physiological and phenotypic differences between EC in the different parts of the arterial tree as well as between arteries and veins optimally support their specified functions in these vascular areas. This review updates the current knowledge about the morphology and function of endothelial cells, particularly their differences in different localizations around the body paying attention specifically to their different responses to physical, biochemical and environmental stimuli considering the different origins of the EC.

This document, supported by both the International Society for Clinical Hemorheology and the European Society for Clinical Hemorheology and Microcirculation, proposes new guidelines for hemorheological methods used in experimental and clinical studies. It is based on a similar document entitled: "Guidelines for measurement of blood viscosity and erythrocyte deformability" published in 1986 by the Expert Panel on Blood Rheology of the International Committee for Standardization in Hematology. Recent methods techniques and instruments, as well as new approaches to interpretation of results, are added to these new guidelines; wide spread adoption should improve comparability between hemorheological laboratories and increase the reliability of rheological tests

The new scanning laser technique allows one to quantify the retinal microcirculation. A digital image analysing system was used to study capillary blood flow velocities and morphological parameters of perifoveal intercapillary areas and foveal avascular zones in normal and diabetic subjects. Diabetic patients showed a significant reduction in capillary blood cell velocities in comparison with normal subjects. Perifoveal intercapillary areas and foveal avascular zones were significantly increased in all stages of diabetic retinopathy, and both parameters increased with progressing diabetic retinopathy. Significant changes in the perifoveal intercapillary areas were observed between normal subjects and patients with no retinopathy.

Spirulina platensis, a multicelluar, photosynthetic prokaryote (algae) contains a high amount of proteins, vitamins and minerals superior to many foods as e.g. soybeans. Thus, Spirulina platensis was recognized as nutritious food by the United Nations World Food Conference. Due to the high amount of nutritive ingredients Spirulina has a long history as dietary supplement. In addition, spirulina platensis is also efficiently used as forage with known effects on flesh, egg and plumage color, milk yield and fertility. The versatile utilization of the alga can be explained on the one hand with the nutrient levels and on the other hand with recognized effects as anti-viral, anti-bacterial, anti-oxidant, anti-diabetic, anti-cancer and anti-inflammatory substance. Therefore, this alga is named as “superfood”. Beyond, these algae convert carbon dioxide into organic substances and produce oxygen during their growth in alkaline and saline water thereby not wasting fresh water allowing the production in barren areas. Despite this diverse use of Spirulina platensis due to its beneficial properties, many basic mechanisms on a molecular and cellular level are not well understood and should be explored in future studies.

We describe a newly developed multi-function video image analysis system for the computer-aided evaluation of capillaroscopic findings in microcirculation research. The Cap image analysis system comprises an IBM-compatible PC with a Matrox image processing card and real-time video tape digitalization. The video recorder is driven by a personal computer to which it is connected via an RS-232 interface. In contrast to currently available systems, the program presented here makes it possible to select any of several integrated image analysis functions, depending on the quality of the video image. Some examples of the analysis functions available are measurements of erythrocyte flow velocity using the line shift diagram method, the spatial correlation method, and the auto flying spot method. The standard features of the new program include a number of special functions and automatic movement correction. The system thus makes it possible not only to measure numerous morphological parameters such as capillary diameter, length, torquation index and capillary density, but also to perform video densitometric analysis, for example using fluorescent dyes.