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574. A further report
408
MISCELLANEOUS DIRECT ADDITIVES
urine contain a protective substance which blocks the precipitation of calcium phosphat in vitro. It was suggested that this substance may be a polyphosphate. Evidence is now pr¢ sented to eortfirm this hypothesis. The plasma was treated with trichloroacetic acid, e~ tracted with ether and further purification carried out by ion-exchange chromatography an recrystallization. The product was isolated as the barium salt, and showed properties ider tical to those of an inorganic pyrophosphate (I). Although the concentration of I in norm,' human plasma is only about 10-SM, this amount is sufficient to protect the tissues from m due calcification. Since pyrophosphate bonding is not strong enough to cause lowering of ionized calciui by complex formation, an alternative theory is put forward involving an interference wit crystal growth and active centres in collagen via a link of I with certain amino acids such lysine and hydroxylysine. 574. ° A further report
Fleisch, H. & Bisaz, Sylvia (1963). Die Pyrophosphatausscheidung im Harn betm gesunde Mensehen. Heir. physiol. Acta 21, 88. An extension of the work described in the previous abstract describes a method for tt quantitative determination of urinary pyrophosphate, involving chromatographic separ~ tion from orthophosphate on Dowex 1 × 10 resin. Application of the method to huma urine revealed striking differences in urinary output of pyrophosphate, in accordance wil sex and age. On a basis of 24-hr output/kg body weight values are highest in childhoc (1-15 yr). Women have a lower output than men but reach higher levels after the menq pause. With increasing age the output falls to very low levels. There is a suggestion of ho monal control and the authors attribute the origin of the pyrophosphate, at least in part, the remodelling of bone.
MISCELLANEOUS DIRECT ADDITIVES 575. Sprout inhibition by y-rays Chopra, V. L. & Swaminathan, M. S. (1963), Sprout inhibition and radiomimetic properti in irradiated potatoes. Naturwissenschaften 50, 374. When embryos of non-irradiated barley seed are grown on a potato mash previous irradiated by X-rays, growth of the barley is inhibited. This effect has been demonstrated I Swaminathan et al. (Radiat. Res. 1962, 16, 182) who suggested that as an experiment finding it was only relevant to food if the effect persisted after irradiation. The prese authors have now established that it does persist. Potato tubers were irradiated with 20 krad of ,r-rays in March and stored cooled un October. The tubers, together with non-irradiated controls, were allowed to sprout, aft which they were used to prepare two sets of mash on which germinating barley embry were planted. When the root tips (meristems) of the embryos were examined microscot eally, micronuclei were found in 2 ~o of the roots from the irradiated mash compared wi only 0.3 ~o of the control roots. It appears that irradiation liberates a substance which inhibits root growth and whi persists for some months. The importance of this finding to the question of safety-in-use irradiated foodstuffs (Cited in F.C.T. 1964, 2, 71) needs no emphasis.
MISCELLANEOUS DIRECT ADDITIVES
urine contain a protective substance which blocks the precipitation of calcium phosphat in vitro. It was suggested that this substance may be a polyphosphate. Evidence is now pr¢ sented to eortfirm this hypothesis. The plasma was treated with trichloroacetic acid, e~ tracted with ether and further purification carried out by ion-exchange chromatography an recrystallization. The product was isolated as the barium salt, and showed properties ider tical to those of an inorganic pyrophosphate (I). Although the concentration of I in norm,' human plasma is only about 10-SM, this amount is sufficient to protect the tissues from m due calcification. Since pyrophosphate bonding is not strong enough to cause lowering of ionized calciui by complex formation, an alternative theory is put forward involving an interference wit crystal growth and active centres in collagen via a link of I with certain amino acids such lysine and hydroxylysine. 574. ° A further report
Fleisch, H. & Bisaz, Sylvia (1963). Die Pyrophosphatausscheidung im Harn betm gesunde Mensehen. Heir. physiol. Acta 21, 88. An extension of the work described in the previous abstract describes a method for tt quantitative determination of urinary pyrophosphate, involving chromatographic separ~ tion from orthophosphate on Dowex 1 × 10 resin. Application of the method to huma urine revealed striking differences in urinary output of pyrophosphate, in accordance wil sex and age. On a basis of 24-hr output/kg body weight values are highest in childhoc (1-15 yr). Women have a lower output than men but reach higher levels after the menq pause. With increasing age the output falls to very low levels. There is a suggestion of ho monal control and the authors attribute the origin of the pyrophosphate, at least in part, the remodelling of bone.
MISCELLANEOUS DIRECT ADDITIVES 575. Sprout inhibition by y-rays Chopra, V. L. & Swaminathan, M. S. (1963), Sprout inhibition and radiomimetic properti in irradiated potatoes. Naturwissenschaften 50, 374. When embryos of non-irradiated barley seed are grown on a potato mash previous irradiated by X-rays, growth of the barley is inhibited. This effect has been demonstrated I Swaminathan et al. (Radiat. Res. 1962, 16, 182) who suggested that as an experiment finding it was only relevant to food if the effect persisted after irradiation. The prese authors have now established that it does persist. Potato tubers were irradiated with 20 krad of ,r-rays in March and stored cooled un October. The tubers, together with non-irradiated controls, were allowed to sprout, aft which they were used to prepare two sets of mash on which germinating barley embry were planted. When the root tips (meristems) of the embryos were examined microscot eally, micronuclei were found in 2 ~o of the roots from the irradiated mash compared wi only 0.3 ~o of the control roots. It appears that irradiation liberates a substance which inhibits root growth and whi persists for some months. The importance of this finding to the question of safety-in-use irradiated foodstuffs (Cited in F.C.T. 1964, 2, 71) needs no emphasis.