Document ba1m0ZVJxYDrjxXD1bRnB5p66

248 Pr o c e e d in g s 6443 Effect of Dietary Calcium and Phosphorus on Toxicity of Lead in the Rat: Rationale of Phosphate Therapy.* DAVID H. SHELLING. From the Harriet Lane Home, Johns Hopkins Hospital, amd the department of Pediatrics, Johns Hopkins University. Since the introduction of calcium salts or calcium containing foods, by Auband his associates,*1 in the treatment of lead poisoning, numerous papers have appeared in the literature advocating such therapy. The rationale of the procedure was based on the following facts : First, the solubility of lead phosphate was found to be analo gous to that of calcium phosphate; hence Aub and his associates believed that lead might be deposited in the bones in the same man ner that lime salts are and thus be removed from the circulation. Second, when diets low in calcium were fed to cats, the trabeculae of the bones of the animals were diminished in size and in number as compared to those of animals fed diets to which calcium had been added. This was interpreted to mean that the addition of calcium salts to diets in generai results in an increased storage of lime salts in the trabeculae; and since lead was supposed to behave like cal cium, its deposition in the bones could be hastened or increased by furthering the process of calcification through the administration of calcium. Third, the fact that lead colic may be alleviated, almost instantly, by the intravenous administration of calcium chloride was thought to add additional evidence that calcium "drives" lead into the bones. Plowever, the later studies of Aub and coworkers2 discredit such an assumption since the alleviation of pain is too rapid to be due to precipitation of lead in the osseous tissue. Aub and his coworkers are, therefore, now inclined to believe that the action of calcium in this instance is to relax the intestinal muscula ture. That the administration of calcium salts does not always result in improved calcification unless the phosphorus in the diet is con trolled, may be inferred from the experiments of McCollum, Ship- * Aided by a grant from Mead Johnson and Company, Evansville, Indiana. 1 Aub, J. C., Fairhall, L. T., Minot, A. S., and Keznikoff, P., Medicine, 1925, 4, 1. 2 Fitzhugh, G-, Miller, M. L., Taylor, G. W., and Aub, J. C., Am. J. Physiol., 1931, 7, 142. Ca l c iu m a n d P ley and Park3 on the pro are reared on diets in w about 1:1, the bones appe to about 4:1a most flori sive intake of calcium o\ cretion of the former fchphate, so that the body ifor calcification. Simila calcium intake, the exen feces as the insoluble cs quently, to osteoporosisciates in their experimen were relatively high in cium metabolism may t to the low-calcium diet decreasing the calciur that the calcium and ph priate value. Later Shi rickets may be produced ; phosphorus but also by tl ity to calcium which ar feces. Rickets has been p: part of the calcium in ric berj-llium, thallium, iron cium of the Steenbock r cium-phosphorus ratio ; When, however, the ren amount of lead so that th equal to the total amoun 4 times that of phosphor he intensified by adding merely adding lead to t' viously, aside from the ti lead diets which contain not lead to improved dq in the bones but, on tht deposition of calcium p 3 McCollum, E. V., Simm E, A., J. Biol. Chem., 1921, 4 4 Shipley, P. G., Park, E E. M,, Bull. Johns Hopkins s Park, E. A., Physiol. Bi DUP050315149 *1 d in ?nt of imng ling. such >ving ialoiates nan:ion. ulae iber )een ium alts calby :ion lost ide sad ire* too .ub the la- alt m- ip- il.. Ca l c iu m a n d Ph o s p h o r u s in Le a d Po is o n in g 249 ley and Park3 on the production of rickets in rats. When animals are reared on diets in which the calcium and phosphorus ratio is about 1:1, the bones appear normal, but when this ratio is increased to about 4:1a most florid rickets develops. Apparently the exces sive intake of calcium over phosphorus results in an increased ex cretion of the former through the intestines as the insoluble phos phate, so that the body is robbed of lime salts which are necessary for calcification. Similarly, if the phosphorus greatly exceeds the calcium intake, the excretion of the excess of phosphorus in the feces as the insoluble calcium salt leads to rickets or, more fre quently, to osteoporosis--a condition produced by Aub and asso ciates in their experiments with cats, since their low calcium diets were relatively high in phosphorus. These derangements in cal cium metabolism may be averted or rectified by adding calcium to the low-calcium diet and by either adding phosphorus to or decreasing the calcium in the low-phosphorus ration, so that the calcium and phosphorus ratio approaches a more appro priate value. Later Shipley ei al.* and others5 demonstrated that rickets may be produced not only by diets high in calcium and low in phosphorus but also by the addition of other cations equal in molal ity to calcium which are excreted as insoluble phosphates in the feces. Rickets has been produced in the rat by replacing the whole or part of the calcium in ricketogenic diets with strontium, magnesium, beryllium, thallium, iron or lead. For example, when part of the cal cium of the Steenbock ricketogenic diet is removed so that the cal cium-phosphorus ratio approaches one, rickets is usually absent. When, however, the removed calcium is replaced by an equimolar amount of lead so that the sum of the amounts of calcium and lead is equal to the total amount of calcium in the Steenbock diet, or about 4 times that of phosphorus, severe rickets develops. The rickets may be intensified by adding calcium to the lead-containing diet, or by merely adding lead to the usual Steenbock ricketogenic diet. Ob viously, aside from the toxicity of the lead, the addition of calcium to lead diets which contain an inadequate amount of phosphorus does not lead to improved deposition of either calcium or lead phosphate in the bones but, on the contrary, it inhibits such a process. The deposition of calcium phosphate in the course of normal ossifica- 3 McCollum, E. V., Simmonds, N., Parsons, H. T.. Shipley, P. G., and Part, E. A., J. Biol. Client., 1921, 45, 383; Bull. Johns 77oplcins Hasp., 1921, 82, 363. * Shipley, P. G., Park, E. A., McCollum, E. V., Simmonds, N., and Kinney, E. M., Bull. Johns Hopkins Hosp., 1922, 83, 210. s Park, E. A., Physiol. Mev., 1923, S, 129. ii ,nn j i DUP05031 51 50 250 Pr o c e e d in g s tion, or the deposition of other insoluble phosphates such as stron tium or lead, can occur only when the phosphorus intake is adequate for their deposition and for the excretion of the excess cations as the insoluble salts in the feces. On theoretical grounds alone, it would seem logical that if the aim of therapy in lead poisoning is to deposit or excrete the lead in an insoluble and hence in an innocuous form, L e., as the phosphate, an abundance of phosphorus or foods containing phosphorus should be supplied. Certainly, the introduction of large amounts of calcium without phosphorus into the animal organisms merely di verts the available phosphorus to rid the body of the excess calcium as the phosphate and thus interferes with the formation of such a compound with lead. The correctness of such an assumption was tested experimentally in rats. Thirty-two rats, 30-40 days old, averaging 65 gm. in weight, the offspring of healthy stock, were divided into 8 groups of 4 each. They were fed 1.5 gm. % of 2PbC03-Pb(0H)2 in the SteenbockBills stock diet6 with and without the additions of either CaC03, Na2HP04 or 3 MgC0s.Mg(0H)2+3H20. Four of the groups re ceived the respective diets without vitamin D while the remainder received the corresponding diets and vitamin D in the form of viosterol 1-D in levels of 1 % of the diet. The compositions of the diets are given in Table I. The animals were allowed food and water TABLE I. ________________________ Composition of Pieta Used. Diet No. 1 Diet No. 2 Diet No. 3 Diet No. 4 Stock +1.5 gm. Diet No. 1+1.5 gm. Diet No. 1+0.9 gm. Diet No. 1+2.75 gm. 2PbC03.Pb(0H)2 Ca0O3 3Mg0O3Mg(OH)2 Na2HP04 (Anhyd.) ? * + Viosterol*? + Viosterolf 9 + Viosterol 3 f + Viosterol The stock diet is that described by Bills0 and contains approximately 0.475 gm. calcium and 0.515 gm. phosphorus % The viosterol was diluted with olive oil to make ID, or equal to cod liver oil in antirachitic potency. The added calcium, magnesium and phosphorus are, approximately, in equimolar amounts. ad libitum, and their weights and changes in health and behavior were noted at frequent intervals. The effect of the variations in the calcium and phosphorus of the diets on the toxicity of lead as indi cated by weight and longevity of the animals is shown in Figs. 1, 2, and 3. It is seen that among the groups not receiving vitamin D, the weight and longevity were the poorest in the following order: 6 Bills, C. E,3 Honeywell, E. M., Wirick, A. M., and Nuesmeier, M., 3. J&iol. Chem., 1931, 90, 619. Ca l Growth curves additions of calc of lead and magi are given in the Same as Pig, 1 diets. DUP050315151 stron:quate as the if the ad in >hate, lould s of y dicium ich a was , the ach. ock- :o3, * relder iosliets iter I Ca l c iu m a n d Ph o s p h o r u s in Le a d Po is o n in g 251 Growth curves of rats fed the stock diet and lead earbonate, with and without additions of calcium, magnesium and phosphate. The formulae for the carbonate of lead and magnesium are abbreviated in Pigs. 1 and 2. The complete formulae aro given in tho text. gm. a.) al jm. oil un. or he li- J ,2 : 3, I k I ii Same as Pig. 1, except that 1% of viosterol ID was added to the corresponding diets. 252 Pr o c e e d in g s C min D mar calcium in t Alagnesh -MgSCh is (2) If phos of lead by that magne . summation shown by 5 that magne solubility o suits of thi 1 view and i: the treatme A few a stock diet a as indicate< were then and in anoi Xa2HPCh poorly. T Pig . 3. Appearance of rats poisoned with lead carbonate. Upper: Female, 117 days on lead and phosphate diet. Weight, 142 grams. Still living. Had litter at 133 days. Lamer: Female, litter mate, 117 days on lead and calcium diet. Weight, 43 grams. Died on 118th day. diet for 20 changed to became less hind legs a parently th MgCOa, > CaCOs, > PbC03 (Without additions). Of the animals receiving PbCOa alone, one is still alive but is failing very rapidly. Those receiving Na2HP04 gain weight steadily and appear normal outwardly. One female of this group had a litter of young after being on the diet for 133 days, but she killed her offspring soon after delivery. With the exception of those in the Na2HP04 group, which are alive and doing well, the animals receiving vitamin D all died sooner than their corresponding mates not receiving the vitamin. The interpretation of these results may be that vitamin D diverted cal cium phosphate into the bones and allowed lead, not combined with phosphate, to circulate freely in the body fluids; whereas in the Na2HP0, group the phosphate was adequate for both deposition stored lead The app of lead pcthe gastrr diets of ci phoras to cation lead insoluble c in the tre: milk, whic but others prescribe phate. It and excretion of the cations (Ca" and Pb+t) as the insoluble phos phate and the animals, therefore, seem well. In the latter case vita- 7 SheffiaBull. Johns 3 Shipley DUP050315153  r dayg on 133 days, eight, 43 mimals apidly. normal g after g soon ch are sooner The :d cali with in the isition phos: vita- Ca l c iu m a n d Ph o s p h o r u s in Le a d Po is o n in g 253 min D may have been helpful in depositing lead along with the calcium in the bones. Magnesium was used in the experiments for two reasons: (1) MgSCL is frequently advocated as a remedy in lead encephalitis. (2) If phosphorus should be a determining factor in the inactivation of lead by forming an insoluble lead compound, it was anticipated that magnesium would increase the toxicity of lead because of the summation of total cations, and also because it was previously shown by Shelling, Kramer and Orent7 and by Shipley and Holt3 that magnesium hinders calcification, probably by increasing the solubility of insoluble phosphate compounds (Ca++, Pb"). The re sults of the experiment with magnesium are in accord with this view and indicate the danger of using soluble magnesium salts in the treatment of lead poisoning. A few animals, not included in the above groups, were fed the stock diet and lead carbonate until they showed evidence of toxicity, as indicated by diminution of activity and loss in weight. They were then placed on the same diets to which, in one group CaCO; and in another group Na^Pth, were, added. Those receiving the Na2HP04 improved rapidly while those getting CaCOs fared very poorly. The animals in the Na2HPC>4 group, after being on the diet for 20 days and showing marked improvement, were suddenly changed to the high calcium diet They lost weight very rapidly, became less active and on the 6th day one developed paralysis of the hind legs and died in convulsions during the following day. Ap parently the sudden ingestion of an excess of calcium liberated the stored lead into the circulation, causing the toxic manifestations. The application of these experimental results to the prophylaxis of lead poisoning in human beings, especially those poisoned by the gastro-intestinal tract, seems obvious. Fortunately, most diets of children and adults contain adequate amounts of phos phorus to take care of calcification and inactivation of the heavy cation lead which requires but a small amount of PO't to form an insoluble compound. In advocating calcium additions to the diets in the treatment of lead poisoning Aub and his associates advise milk, which contains, besides calcium, an abundance of phosphorus; but others, not realizing the phosphorus factor in this process, prescribe large amounts of calcium salts other than the phos phate. It would also seem that not only is phosphorus important in t Shelling, 3D. H., Kramer, B., and Orent, E. It., J. Biol. C/vem., 1928, 77, 157 j Bull. Johns Hopkins Hosp., 1927, 41, 426. a Shipley, P. G., ana Holt, L. B., Jr., Bull. Johns Hopkins Hosp., 1927,41, 437. til ai: .KJ sur 5\ iredt ty he na. rit; irr M DUP050315154 254 Pr o c e h mn g s depositing lead in the bones but also in attempting to delead at a future date. This may be accomplished by giving a diet low in calcium and relatively high in phosphorus so that the cations re moved from the bones are excreted as the insoluble phosphates. The metabolism data of Aub and his associates indicate that, aside from its acidity, HnPO, was the most effective substance in delead ing patients suffering from chronic lead poisoning. More extensive experiments on the effect of dietary calcium and phosphorus in lead and thallium poisoning in rats, induced by oral and subcutaneous administration, are now in progress. The results of these experiments and also of those obtained with phos phate therapy in human cases of plumbism will be reported later. 6444 Relation of Pressure to Rate and Quality of Milk Secreted." pressure from ti: the variations cas of milk in the ut maximum pressu Two methods the maximum prt meter and (2) d milk is secreted l; To measure the in the udder a ms in the teat canal, the milk would ri While the left permitted to accun intervals with a 5 the milk was draw frequently. Two repeated. W. E. PETERSEN an d T. V. BIGOE. From the Division of Dairy Husbandry, University of Minnesota. Trial Xntjr Recent work1'1 has shown that milk secretion takes place in the interim between milkings, and that practically all milk drawn at a milking is present in the udder at the time of milking. It is evi dent, therefore, that pressure must develop in the duct system as the Cow E 03 01 1 hr. 21 2+ 36 36 I I secretion accumulates. The purpose of this work is to establish the amount of pressure developed by the accumulating secretion; the effect of such pressure upon the rate of secretion; and the maximum 1 Cow lid 1 120 120 21 21 pressure against which milk will be secreted. Neusch,3 Isaachsen,4 and Tgetgel5 measured the pressure in the udder at milking time and reported wide differences due no doubt 12 36 36 1 120 o 120 to a difference in distention of the gland, and as they measured the * The data used in this paper are taken mainly from a thesis presented by T. T. Eigor in partial fulfillment for the Ph.D. degree. Published with the approval of the Director as Paper No. 1110, Journal Series, Minnesota Experiment Station. r Petersen, W. E,, Palmer, L. S., and Eckles, 0. H., Am. J. Physiol., 1929, 90, 573. 2 Swett, W. W.,Dairy Sci., 1927, 10, X. 3 Neuseh, J., Uber das Sog. Aufaieben der Milch, 1910, Paul Pare?, Berlin. Isaachsen, H., Pros. World's Dairy Congress, 1923, 2, 1018. 5 Tgetgel, B., Schweisrer Arch. f. Tierheil., 1926, 68, 335, 369. Table I gives the developing the same milk in the gland re the maximum pressu for cow E93 it took . at 24 hours than at tained there is a fall 12 hours. This is dt sorption of the jmxlu DUP050315155