Cellular Cancer Therapy, part 3

Chapter 2    Properties of the cell membrane

    Cells are bounded by a thin layer of molecules that responds to physico-chemical influence. This delicate cell membrane is made up of complex lipoproteins and is in close contact with the cytoplasm; it is semi-permeable and functions as a reversible colloid.

    The interface of two heterogeneous systems in contact generates a kind of membrane that has the tendency to reduce its surface area, demonstrating a force called surface tension.

    The cell membrane is formed by the intervention of tenslo—active substances that, concentrating on the separating surface, form a superficial condensation; the proteins and other substances that make up the cell also have a tendency to concentrate at the separating surface, as well. This accumulation of molecules that are necessary for the cell’s equilibrium, in certain cases provokes the coagulation or freezing of the proteins.

    All living matter is composed mostly of bodies that possess the property of considerably reducing the surface tension of the water in which they are in solution within the organism. If a body in solution has the property of reducing the surface tension of the solvent, it will concentrate at the separating surface so that the final equilibrium state of the system will have a minimum of free energy.

    The tensio—active substances that contribute to the formation of the membrane reduce its permeability because they increase its surface tension. Dissolved, ionized salts reduce surface tension. thus increasing the permeability of the membrane; this same effect is produced by the anions and cations that are formed. The surface tension decreases with an increase in temperature, disappearing completely at the liquid’s boiling point.

    The removal of the constituents of the cell membrane, that is, the modification of the surface tension by changing the environment surrounding those constituents, modifies the permeability of the membrane’s interstices, making permeable those that were semi-permeable, or vice— versa.

    When the cytoplasm loses water the membrane is attracted to the center of the cell through its retraction, and an empty space appears between the external covering and the cytoplasm.; this is called plasmolysis. When water gets into the cytoplasm, in contact with a hypotonic solution, there is considerable swelling.

    Any modification of the solubility of the proteins by the protoplasm, as well as a change in pH, will determine a change in the dimensions or in the shape of the cell. Cellular proteins are ampholytes, i.e., those electrolytes that have, at the same time, acidic and basic functions. The release of these ions depends on the reaction in the environment: in an acid environment, with a high concentration of H+ ions, the release of these is blocked and the protein behaves like a free base; the opposite happens in a strongly alkaline environment where the OH- ions are released and the ampholyte behaves like a free acid, possibly combining with these bases.

    In sum, when an ampholyte is placed in a beaker with electrodes, it moves to the negative pole in an acid medium, and inversely, when the net situation is electrically neutral, it will not behave either as an anion or a cation, remaining neutral. This electrical neutrality does not usually conform to the postulates of chemistry, but each ampholyte has a specific value and the constancy of this characteristic is its isoelectric point.

    The activity of’ the cell depends on the electrocapillary effects introduced by the molecular condenser which is the result of the orientation of the proteins in the membrane.

    The displacement of the molecules in a solution can vary from the point of greatest to that of’ least concentration, in spite of gravity and molecular cohesion: it is possible for a substance to diffuse from a zone of low osmotic pressure to zones where the osmotic pressure is higher whenever the concentration of the substance is higher in the first.

    The kinetic energy that molecules develop to distribute themselves uniformly, makes for a certain pressure in the recipient where they are; this is called osmotic pressure. The rate of diffusion will depend on the size of the molecules and the diffusable substance, and on its molecular weight and electrical charge.

    Crystalloids are substances that diffuse more quickly and almost all at the same rate; on the other hand, colloids diffuse only with difficulty or not at all.

    The osmotic pressure of a solution depends on three primary factors: concentration of the substance, its nature, and the temperature. Electrolytes behave as normal molecules.

    An increase in temperature and concentration of crystalloids increases the osmotic pressure; at the same concentration, binary electrolytes behave as normal molecules.

    An increase in temperature and concentration of crystalloids increases the osmotic pressure; at the same concentration, binary electrolytes yield approximately twice the osmotic pressure; that of colloids is low or zero.

    Any modification in the solubility of the proteins of the protoplasm as a consequence of the change in pH and with it the change in osmotic pressure (which is more common), determines a change in the dimensions or in the shape of the cell; the concentration of biological liquids, within certain limits, works the same way.

    In sum, the osmotic pressure is especially important as the fundamental state of the internal organic environment; this pressure cannot deviate very much from a certain value without seriously damaging the protoplasm; thus it is important that it remains constant. It should be noted, too, that erythrocytes are very sensitive osmometers.

    So that normal cell functions can be carried out, it Is necessary that the osmotic pressure be consistently constant both within the cell and in the surrounding environment, since the protoplasm is a complex system in which the ratio between the water and the dissolved substances can only vary within a very limited range.

    The small variations in the quantity of protoplasmic water are immediately revealed in abnormality of cell functioning, and this becomes more important as the function of the affected cells becomes more delicate. Every difference in isotonia has toxic effects; this can be called osmonocivity,

    In the organism, sensitivity to water varies according to function; this is one of the elements that affect the cell’s physico—chemical constant. Any change in the blood is transmitted to the tissue liquids and finally to the cells, Life Is a colloidal complex whose physico— chemical properties are constant, depending on the surrounding environment; they vary within a very limited range and correspond to the different functions of the organism: rest, physical or mental exertion, feeding, fasting, etc.

    Besides the changes discussed above, there Is that of the blood’s pH, which is maintained constant through a special system of three regulating salts: carbonic and bicarbonic acid, primary and secondary phosphates and the amphoterism of protides, These regulating systems are an index of potential alkalinity and are what is called the blood’s alkaline reserve,

    Cells have the ability to keep their reactions constant when the pH Is near neutral (pH = 7,35); the slight variations in blood pH do not affect cell pH. When there is a considerable change, however, the reaction of the cytoplasm changes greatly, though not for a prolonged period, since this would cause cytolysis.

    The rate of the intracellular reaction is proportional to the concentration of the ions. The substrate of the cell protoplasm is made up of substances that are very sensitive to the effects of H+ and OH-.

    Not only phenomena of diffusion and osmosis regulate changes in the solvent, but due to inhibition pressure certain colloids absorb water, according to their properties; sometimes this phenomenon can run counter to the laws of osmosis, The solvent where these physico-chemical phenomena take place is water which constitutes 68% of the blood.

    There is a permanent fixed state of fluidity that permits normal functioning. We still cannot determine the minimal quantity of water necessary to maintain life; but it has been demonstrated that the smaller the amount of water, the lower the level of activity of’ the organs and organisms. This demonstrates that vital activity is closely related to the proportion of water in the cell.

    The water In the cells is partially in a chemical combination with the substances that are found in contact with it, there being veritable colloidal ions (micelles with variable electrical charge), that are more or less voluminous, and which we can consider as a nucleus of attraction for a variable number of water molecules with which it forms different compounds (degree of hydration or imbibition of the colloids).

    When one wishes to extract water from colloids, resistance is found that expresses the attractive force which unites the solvent and the colloid ions. The affinity between the solvent and the colloidal micelles is weak, as is the case with glucogen; the water is not found in an imbibed state and its physico-chemical properties are not profoundly changed.

    When the micelles of a colloid pass from the state of ions to that of electrically neutral micelles, a change is produced in the water that is totally or partially combined with the protoplasm.

    The real reaction of the cells is lower than that of the blood; we could say that the cytoplasm has an average reaction corresponding to pH6, due to which the metabolic functions (release of carbonic acid) acidify the cytoplasm more and more as a function of increased activity.

    The blood requires a minimal concentration of glucose, for which reason it is the immediate fuel and most directly usable material for all cells. The blood has a constant osmotic pressure between —0.55° and -0.58°C measured by cryoscopy. For the realization of cell functions a: constant osmotic pressure is necessary in the cells and in their environment; they are similarly accustomed to a fixed, determined surface tension of the liquids that surround them.

part 4