Paton, David M.

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27 June 1964 S.A. JOURNAL OF LABORATORY A Dell (CAL MEDICI E 5Lbranchial cyst. The remains of the cervical sinus maypresent an opening in the skin at the lower part of th~neck along the front margin of the sterno-mastoid,l anda branchial fistula results. In Braus' schematic illustrationalready referred to, the cervical sinus is shown linked u;on one side with the second pharyngeai pouch and on theother side with the third pharyngeal pouch. The smallchannels linking the sinus with the pharyngeal poucheswould be remains of the epithelium lining the second andthird external pharyngeal clefts. A communication maybecome established with the corresponding pouches, thusexplaining the presence of lymphoid tissue or of thymictissue, or of both in the walls of the branchial cyst. It alsoexplains the term lympho-epithelial cyst favoured byKing.5However, the right and left thymic diverticula describedhere, are obviously independent structures, not linked witha persisting cervical sinus. Any cyst in the neck which hadarisen from such a diverticulum would have to be called athymic cyst, not related to the ordinary type of branchialcyst. The usual embryological interpretation of thymiccysts appears to be the correct one, and the arguments putforward by King cannot be accepted.MMAR A 0 co L 10A ca e of persi tent thymu di erticulum on both ide ofthe neck i de cribed. Thi congenital abnormality wafound in an adult ubject in the di ecting room. Thestalk of the diverticulum blended on each ide with thethyroid and parathyroid gland and, on the right ide, thediverticulum was traced to a pocket in the interior of thepharynx situated at the lower end of the piriform fo a.This was thought to repre ent the remain of the thirdpharyngeal pouch; the pocket being pre ent on both ides.After considering the embryology of the thymu gland.its relationship to thymic cy t and to branchial cysts idiscussed. Despite a contrary opinion expre sed in surgicalliterature, it is concluded that the existence of branchialcysts derived solely from thymic remnants in the neckmust be accepted.R FERE 'CESI. Braus, H. (1924): Allatomie des Memelr",, Band 11. pp. 114, 115.Berlin: Springer.2. Brash. J. C. ed. (1951): CUllllillglram's Text-book of Anatomy, 9th 00.,p. 819. London: Oxford University Press.3. Patten. B. M. (1946): Humall Embryology, pp. 539, 540. Philadelphia:Blakislon.4. Cote, R. and FOrlin. C. (1961): Canad. J. urg .. 4, 566.5. King, E. S. J. (1949): Aust. N.Z. J. Surg .. 19, 109.THE CHOLESTEROL-SOLUBILIZING POWER OF BILIARY LIPIDSDAVID M. PATON, M.B., CH.B. (CAPE Tow), Department 01 Physiology and Pharmacology, Universily 01 Cape TOWlIBiliary cholesterol has long excited interest, since it wasshown that cholesterol was an important constituent ofmany gallstones and thus might be of aetiological impor-tance in their formation.1 Since cholesterol is present inbile in a concentration beyond that at which it is normallysoluble in triglycerides at body temperature,2 the continuedstate of solution of it in the oily phase of bile mustdepend on the presence of other factors. This problem hasbeen approached in a number of ways. There are indica-tions that both bile acids1 and biliary phospholipids3 in-crease the solubility of cholesterol in bile.The ability of phospholipids to 'solubilize' other lipids intissues has been outlined elsewhere.4 The factors thatkeep serum cholesterol in the oily phase have also beeninvestigated. The addition of very small amounts of totalserum lipids to a supersaturated cholesterol solution in atriglyceride oil not only increases the stability of thesolution but also depresses the rate of crystallization ofthe sterol.5, 6 This property of the serum lipids could beattributed to the action of the combined serum phospho-lipids; consequently, it was suggested that the serumphospholipids might help to maintain the solubility ofserum cholesterol in the circulating plasma lipids.6The effect of the total biliary lipids on a supersaturatedsolution of cholesterol in a triglyceride oil has beeninvestigated for the following reasons, namely:(a) It appeared to be a simpler method than certainothers1,3 for studying the stabilizing factors present inbile in health and disease.(b) A study of the effect of the total serum lipids onthe same test system has proved useful. Ischaemic heartdisease,5,6 the administration of adrenaline,7 and surgicalstress,S have all been shown to reduce the stabilizing effectof the total serum lipids.This paper deals with the re ults of a preliminaryinvestigation into the effect of the total biliary lipid onthe stability of a supersaturated solution of chole terol ina triglyceride oil.MaterialBile was obtained from the following ources, namely,(a) from patients with postoperative T-tube ,(b) from rabbits and cats with tube in the common bileduct while anaesthetized with 'pentobarbitone', and(c) from direct puncture of the gallbladder in dogs.The bile was stored at a temperature lower than O°C.until used.MethodsThe method of Wilkens and Krut6 (1963), designed tostudy the effect of the total erum lipids on the tabilityof cholesterol-triglyceride olution, wa used with thefollowing changes, namely(a) I ml. of bile was used in tead of I ml. of fastingserum, and(b) exactly }·25 G. of cholesterol, instead of about }·75 G.,was dissolved in the triglyceride oil.Crystallization rate value. The maximum cry tallizationrate (CR value) was computed as described by Wilken andKrut.6 In each ca e the CR value produced by a sample oftotal biliary lipids was compared with the 'R value ofthe standard solution to which no biliary lipid had beenadded.Result.\'The addition of mall amount of total biliary lipid toa supersaturated solution of cholesterol in a triglycerideoil not only increa ed the tability of the olution but al52 S.A. TYDSKRIF VIR LABORATORIUM- EN KLINIEKWERK 27 Junie 1964markedly depressed the rate of crystallization of the sterolwhen crystallization did occur (fable I). The eR valuesof different samples of bile also varied.TABLE I. THE STABILIZING EFFECT OF BILIARY LlPIDS ON CHOLESTEROLSubjects ControlsVolume ofAnimal bile used (ml.) CR value CR valueCat I 1·0 2·60 4·01Cat 2 1·0 1·96 4·01Cat 3 1·0 2·05 3'73Cat 4 1·0 1·43 4·01Rabbit 1 1·0 2·16 4·01Rabbit 2 0·8 2·45 4·01Rabbit 3 0·5 3·49 4·01Rabbit 4 1·0 2·75 3·49Man 1 1·0 3·49 4·01Man 2 1·0 1·88 3·73Man 3 1·0 3·08 4·01Man4 1·0 2·75 3·73Man 5 1·0 3·49 3·73Man 6 1·0 1·73 4·01Man 7 1·0 2·36 3·73Man 8 1·0 1·00 4·01Dog 1 1·0 .1·96 4·01DISCUSSIONThe nature of the stabilizing factors present in the totalbiliary lipids used remains to be determined. It wouldseem likely, however, that the bile salts and phospholipidsmight account for this property. .Molecules of bile salts in solution will at certain criticalconcentrations aggregate to form larger molecular massescalled micelles. Once these micelles are formed, theability of the solution to dissolve cholesterol is increased.9Preliminary results likewise suggest .that the addition ofsodium taurocholate to the cholesterol-triglyceride solutionincreases the stability of the contained cholesterol.The addition of lecithin to bile increases its cholesterol-holding capacity.3 The stabilizing effect of the total serumlipids on the cholesterol-triglyceride solution used waslikewise found to be attributable to the effect of thephospholipids.5,6Lecithin has been shown to increase the stability ofcholesterol in the cholesterol-triglyceride solution, whileinositol and lysolecithin cause a decrease in stability;however, none of these phospholipid fractions were pure.6Presumably the decreased stabilizing power of the totalserum lipids found in patients with ischaemic heart di-sease,5,6 in animals after the injection of adrenaline,7 andin animals during surgical operations,8 is related to a rela-tive and/ or absolute change in these phospholipid fractions.Until quite recently it was believed that lecithin wasthe only phospholipid present in bile ;10 however, since1960, it has been shown that several other phospholipids,e.g. cephalin, sphingomyelin and lysolecithin, are alsopresent.2, 11, 12 This would suggest that changes in therelative and/or absolute amounts of biliary phospholipidscould produce changes in cholesterol stability. Bearing thispossibility in mind, a study of the effect of biliary lipidson cholesterol stability under various conditions (e.g.cholelithiasis) has been started.Although such studies into the physicochemical proper-ties of bile salts, cholesterol and phospholipids are nodoubt important in the elucidation of the problem ofgallstone formation, it has been rightly pointed out thatother factors, such as biliary stasis, infection and foreignbodies, may also be of aetiological importance.I,9SUMMARYBiliary lipids increase the stability of cholesterol in acholesterol-triglyceride solution and decrease the rate ofcrystallization of cholesterol when crystallization occurs.The possible role of these findings in relation to biliarypathology is discussed.I wish to thank Prof. A. W. Sloan and Prof. N. Sapeika fortheir encouragement and for the provision of facilities. Thisstudy was supported by a research grant from the FourcadeBequest to the University of Cape Town.REFERENCES1. Rains, A. J. H. (1962): Brit. Med. J., 2, 685.2. Turner, D. A. (1962):. Fed. Proc., 21, Supp!. 11, 25.3. Johnston. C. G. and Nakayama, F. (1951): Arch. Surg., 75, 436.4. Dixon, K. C. (1958): Quart. J. Exp. Physio!.. 43, 139.5. Wilkens, J. A. and Krut, L. H. (1962): S. Mr. J. Lab. Clin. Med.,8. 123.6. Idem (1963): J. Atheroscler. Res., 3, 15.7. Wilkens, J. A. and Sapeika, N. (1964): J. Atheroscler. Res. (in theDress).8. Paton, D. M. and Wilkens, J. A. (1964): (In the press).9. Rains, A. J. H. (1961): Ann. Roy. Coli. Surg. Eng!., 29, 85.10. Johnston, C. G., Irvin, J. L. and Walton, C. (1939): J. Bio!. Chem.,131. 425.11. Philips, G. B. (1960): Biochim. biophys. Acta (Amst.), 41, 361.12. Nakayama, F. and Blomstrand, R. (1961): Acta chem. scand., IS, 1595.NITROGEN, FAT AND MINERAL BALANCE STUDIES IN PATIENTS WITHPROTEIN MALNUTRITIONP. J. PRETORIUS, M.MED. (PAED.), M.D., Department of Paediatrics, University of Pretoria, and National NutritionResearch Institute, South African Council for Scientific and Industrial Research, Pretoria; AND A. S. WEHMEYER,M.Se., National Nutrition Research Institute, Council for Scientific and Industrial Research, PretoriaSeveral papers have been published on nitrogen and fatbalance in infants with protein malnutrition. Much less isknown about mineral salt balances and the relationshipbetween the retention of nitrogen and the retention of themajor intracellular ions.It has become increasingly evident that infants withkwashiorkor are depleted not only of protein, but also ofseveral minerals, including potassium,I,2 phosphorus,3 andmagnesium.4 In view of the importance of these mineralsas intracellular ions, and their essential role in manymetabolic processes, a study was undertaken of the nutri-tional state of kwashiorkor patients in our area withregard to these minerals. Nitrogen, fat, calcium and sodiumbalances were carried out concomitantly.MATERIALS AND METHODSThe investigations formed part of a more comprehensivestudy5 designed to assess the effect of milk fat and sun-

The cholesterol-solubilizing power of biliary lipids

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The cholesterol-solubilizing power of biliary lipids

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