Plasma calcium difference between man and vertebrates

From organic and inorganic phosphates to valvular and vascular calcifications

Calcification of the arterial wall and valves is an important part of the pathophysiological process of peripheral and coronary atherosclerosis, aortic stenosis, ageing, diabetes, and chronic kidney disease. This review aims to better understand how extracellular phosphates and their ability to be retained as calcium phosphates on the extracellular matrix initiate the mineralization process of arteries and valves. In this context, the physiological process of bone mineralization remains a human model for pathological soft tissue mineralization. Soluble (ionized) calcium precipitation occurs on extracellular phosphates; either with inorganic or on exposed organic phosphates. Organic phosphates are classified as either structural (phospholipids, nucleic acids) or energetic (corresponding to phosphoryl transfer activities). Extracellular phosphates promote a phenotypic shift in vascular smooth muscle and valvular interstitial cells towards an osteoblast gene expression pattern, which provokes the active phase of mineralization. A line of defense systems protects arterial and valvular tissue calcifications. Given the major roles of phosphate in soft tissue calcification, phosphate mimetics, and/or prevention of phosphate dissipation represent novel potential therapeutic approaches for arterial and valvular calcification.

Pathological calcification and replicating calcifying-nanoparticles: general approach and correlation

Calcification, a phenomenon often regarded by pathologists little more than evidence of cell death, is becoming recognized to be important in the dynamics of a variety of diseases from which millions of beings suffer in all ages. In calcification, all that is needed for crystal formation to start is nidi (nuclei) and an environment of available dissolved components at or near saturation concentrations, along with the absence of inhibitors for crystal formation. Calcifying nanoparticles (CNP) are the first calcium phosphate mineral containing particles isolated from human blood and were detected in numerous pathologic calcification related diseases. Controversy and critical role of CNP as nidi and triggering factor in human pathologic calcification are discussed.

Theory about aging in humans and hypotheses about its possible delay

Living beings can maintain their metastable state, e.g. can escape from the first law of thermodynamics by being open systems, by taking up high energy molecules and by dissipating waste products, heat and work. According to the present theory they can stay alive as long as they can escape from the external chaos which is due to the second law of thermodynamics. It is argued that aging is caused by penetration of this chaos into our body in the form of excess trace elements and as xenobiotic elements which either stop the functioning of our living cells or bring it out of neural or hormonal control. Aging might be delayed by the fact that sulfur metabolism maintains an H2S tension in the human body able to precipitate the xenobiotic elements from our tissues. For our defense we depend further on phagocytes to transport the precipitates to organs where they can be dissolved and excreted. It is suggested that the regular passing of kaoline, a natural cation exchanger, through the intestinal tract will help to extract the xenobiotic elements from the body. As far as cardiovascular diseases are concerned, they start with the inevitable tendency of triglycerides to form crystalline precipitates at the surface of the intima in the arteries and capillary vessels. It is hypothesized here that cholesterol serves as a complex former, together with yet unknown plasma protein factors to the triglycerides enabling the solubilization of the precipitates. It is supposed to act as a sort of hormone.(ABSTRACT TRUNCATED AT 250 WORDS)

Louis Bolk revisited. II--Retardation, hypermorphosis and body proportions of humans

A number of morphological particularities of humans, generally thought to be specializations produced by natural selection, arguably are instances of hypermorphosis: alterations in proportion brought about by simple prolongation of general embryonic allometries. The descended larynx, the flattened human chest, and several limb proportions are given as examples. The case of the human foot, often quoted as an example of advanced specialization in humans, is examined in some more detail. Besides, it is argued that the human growth pattern displays a unique 7-year periodicity unlikely to be the result of the erratics of Darwinian evolution. Developmental acceleration is the unavoidable correlate of animal specialization; it brings about the breakdown of the periodicity present in the generalized humanlike development and causes the embryonic allometries to be cut off prematurely in the non-human mammal.

The roles of intracellular buffers and bone mineral in the regulation of acid-base balance in mammals

1. Regulation of intracellular and extracellular pH may conflict in their requirements for movement of acid or base. 2. Cells make a positive or a negative contribution to 'tissue buffering' of extracellular fluid (ECF), depending on their internal buffer value, on the tightness of their internal pH control by membrane mechanisms, and on the nature of the acid-base disturbance. 3. A role is suggested for electrogenic Na-HCO3 co-transport in some of the ion shifts that occur in acid-base disturbances. 4. The time course of 'tissue buffering' in nephrectomized mammals in hypercapnia is variable, and it is far from clear in intact, unanaesthetized mammals. 5. Buffering of ECF by Ca salts of bone mineral in acidosis can only be substantial if accompanied by Ca excretion; the release of HCO3 with Na and K is more significant. 6. The relative importance of cells and of bone mineral in the buffering of ECF is unclear.

Proteoglycans synthesized in vitro by nude and normal mouse peritoneal macrophages

Peritoneal macrophages from nude mice were found to be functionally similar to 'activated' macrophages from normal mice. The objective of the present study was to characterize the proteoglycans synthesized and secreted in vitro by peritoneal macrophages isolated from nude and normal Balb/c mice and to investigate the relationship between macrophage 'activation' and changes in the proteoglycan patterns. Macrophages obtained by peritoneal lavage were seeded in Petri dishes. After 2 h incubation at 37 degrees C, the adherent cells (macrophages) were exposed to [35S]sulphate for the biosynthetic labelling of proteoglycans. After incubation, the cell and medium fractions were collected and analysed for proteoglycans and glycosaminoglycans. The glycosaminoglycans were identified and characterized by a combination of agarose gel electrophoresis and enzymatic degradation with specific mucopolysaccharidases. It was shown that 3/4 of the total 35S-labelled glycosaminoglycans were in the extracellular compartment after 24-48 h. The macrophages synthesized dermatan sulphate (68%), chondroitin sulphate (7%) and heparan sulphate (25%). Both cell and medium fractions of normal and nude mouse macrophages contained glycosaminoglycans with the same ratios, although the nude mouse macrophages synthesized 2-fold less glycosaminoglycans than the normal mouse macrophages. Lower levels of 35S-proteoglycans were also obtained from in vitro 'activated' macrophages, but the ratios of dermatan sulphate:chondroitin sulphate: heparan sulphate were altered in these cells as compared to the control. Furthermore, all the 35S-macromolecules found in the extracellular compartment of nude and normal control cells were of proteoglycan nature, in contrast to the medium fractions of 'activated' macrophages, which contain both intact proteoglycans and 'free' glycosaminoglycan chains. These results indicate that, at least as regards the proteoglycans and glycosaminoglycans, the nude mouse macrophages are not identical to the 'activated' macrophages from normal mice.