Colloidal Calcium Phosphate Research Articles

Histochemical studies on the fate of colloidal calcium phosphate in the rat

Histochemical studies on the fate of colloidal calcium phosphate in the rat

The State and Partition of the Calcium and Inorganic Phosphorus in the Serum of the Fowl. Effect of Growth and Ovulation

INTRODUCTIONTHE partition of the calcium and inorganic phosphorus in the blood stream of the fowl during ovulation has recently been the subject of extensive experimental investigation (Laskowski, 1935; Benjamin and Hess, 1933; Correll and Hughes, 1933; Heller and Thompson, 1934). Little data, however, are available on the changes and partition of these elements in the blood of the fowl during growth. This, together with the fact that the nature of the calcium compounds which produce the great augmentation in the serum calcium level of the hen during ovulation has not been definitely established by previous investigators, led us to undertake the present study.It is generally agreed that the augmented level of serum calcium during ovulation is virtually confined to the non-diffusible fraction. Laskowski (1933) has suggested that this extra calcium is present in the form of a colloidal calcium phosphate compound. Benjamin and Hess (1933) and Heller, Paul .

134. The Titration of Milk and Whey as a Means of estimating the Colloidal Calcium Phosphate of Milk

1. The titration method for the estimation of colloidal tricalcium phosphate in milk was found to agree closely with the determination of total colloidal inorganic P2O5.2. The method was used to study the solution of tricalcium phosphate in milks of rising acidities.3. Close agreement was obtained between the actual increase in total P2O5 in the wheys of souring samples and that calculated from the disappearance of tricalcium phosphate as found by the titration method.4. The discrepancy between the actual increase in whey calcium in such cases and that calculated from the titration figures was attributed to the solution of calcium from the calcium salt of caseinogen. From figures so obtained it would appear that colloidal calcium phosphate dissolves with greater ease in milk than the calcium of the protein salt.5. A linear relationship was found to exist between the ordinary titration value of milk and the three other values used in this estimation, and also between the curd acidity and milk acidity.6. Average figures are given for the tricalcium phosphate content of the samples studied and for the various titration factors.

Colloidal Calcium Phosphate of Blood and Calcium Partition in Serum

It has now been thoroughly shown that under certain conditions the inorganic phosphate of the serum becomes incompletely diffusible. A logical explanation of this phenomenon is that the non-diffusible phosphate which is formed is combined with some of the serum calcium in a compound which is in a colloidal state. As yet, no direct evidence is available as to the exact composition of this colloidal calcium phosphate. On the basis of the view which has recently received strong support from the work of McLean and Hastings, namely, that there is an equilibrium between the ionized and the protein bound calcium in serum which is governed by the mass law, it appears possible to develop a relationship which will quantitatively account for the partition of the serum calcium and one which will also yield a plausible value for the composition of the colloidal calcium phosphate. In the following treatment it is assumed that the diffusible calcium is virtually equivalent to the ionized calcium of the serum. This opinion also is supported by the work of McLean and Hastings. where P represents the protein, CaP the calcium protein complex, and CaD++ the diffusible calcium. A and B are constants whose significance is given below. The equation as given has the advantage that if the observed data obey the mass law, then a straight line is obtained on plotting the values of P/CaP against 1/CaD++. The value of the constant A is given by the reciprocal of the point of intersection of the straight line on the P/CaP axis. It has the significance of being the maximum amount of calcium which can be bound by each unit weight of protein. The slope of the straight line gives the value of the constant B. This term consists of the equilibrium constant divided by A.

CALCIFICATION IN THE SUBCUTANEOUS TISSUES

A brief resume of the various theories advanced to explain the formation of the deposits of calcium or calcification follows. Pauli and Samec1showed that in a colloidal albuminous solution, calcium carbonate and calcium phosphate are many times more soluble than in water. These salts could therefore be carried in the blood in nearly the same form as they are found in the deposits. Holt, La Mer and Chown2demonstrated that blood serum is normally saturated up to 200 per cent with neutral calcium phosphate, and that this salt will remain for days without precipitating. They thought, however, that most of the calcium is carried in the form of the much more readily soluble acid carbonate and acid phosphates which may be changed into the neutral salts by the loss of carbon dioxide. Barille3held that calcium is contained in the blood as a double salt, calcium