The binding of 14C-labelled porphyrins by plasma proteins

Koskelo, Pentti; Toivonen, Ilkka; Rintola, P.

doi:10.1016/0009-8981(70)90028-8

Cited by 42 publications

(11 citation statements)

References 16 publications

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“…Spontane ous remission may occur [16] but is rare. Morever, in agree ment with others [17] our own studies on porphyrin clear ance during HD using standard Cuprophan and highly permeable PAN membranes failed to reveal any significant porphyrin clearance, probably because of protein binding of porphyrins [18] thereby making plasma exchange [16] the most logical way of lowering porphyrin at least temporarily in acute circumstances.…”

Section: Discussionsupporting

confidence: 49%

Haemodialysis – Related Porphyria Cutanea Tarda and Treatment by Recombinant Human Erythropoietin

Yaqoob¹,

Smyth

Ahmad³

et al. 1992

Nephron

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Haemodialysis-related porphyria cutanea tarda is a rare, but serious and mutilating skin condition, resulting from extremely high plasma porphyrin levels because of their inadequate clearance by haemodialysis. The treatment is very difficult as chloroquine is ineffective and venesection, the conventional treatment of this disease, is not always an option because of anaemia of end-stage renal disease. We report a case of haemodialysis-related porphyria cutanea tarda and her successful management by recombinant human erythropoietin treatment.

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Section: Discussionsupporting

confidence: 49%

Haemodialysis – Related Porphyria Cutanea Tarda and Treatment by Recombinant Human Erythropoietin

Yaqoob¹,

Smyth

Ahmad³

et al. 1992

Nephron

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“…The plasma proteins that bind protoporphyrin most strongly appear to be hemopexin and albumin (28,29). While it may be that hemopexin binds PP somewhat more strongly than does albumin, the large ratio of concentrations of albumin to hemopexin, approximately 100:1 in all species examined (30) served for erythrocytes obtained from both EPP patients and GFPP mice.…”

Section: Methodsmentioning

confidence: 95%

Comparative Study of Protoporphyrins in Erythropoietic Protoporphyria and Griseofulvin-Induced Murine Protoporphyria

Poh–Fitzpatrick¹,

Lamola²,

Zalar³

et al. 1977

J. Clin. Invest.

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A B S T R A C T Excess erythrocyte protoporphyrins of human congenital erythropoietic protoporphyria and of griseofulvin-induced murine hepatic protoporphyria were found to be associated with hemoglobin and stroma fractions in similar relationships. More than 99.5% of total erythrocyte protoporphyrin was bound to hemoglobin in each case. However, profound differences were found when protoporphyrin concentration was measured in erythrocytes that had been segregated into populations of progressive age on discontinuous density gradients. In erythropoietic protoporphyria, porphyrin content diminished rapidly with age; in murine protoporphyria, the aging erythrocyte populations became progressively more porphyrin rich. In vitro diffusion of protoporphyrin from plasma across the intact erythrocyte membrane was demonstrated. The equimolar binding affinity of protoporphyrin to hemoglobin was shown to be 40 times that of protoporphyrin to serum albumin. This strong affinity provides the driving force for the observed transmembrane diffusion, and explains the high erythrocyte/plasma porphyrin ratio in murine hepatic protoporphyria. The opposite rapid efflux of intraerythrocytic protoporphyrin into plasma previously shown in uncomplicated erythropoietic protoporphyria occurs despite this strong hemoglobin affinity, implying continuous efficient clearance of protoporphyrin from plasma by the liver. Furthermore, these and other This work was presented in part at the 7th International Congress on Photobiology, Rome, Italy, September, 1976. Received for publication 22 November 1976 and in revised form 29 March 1977. data suggest that a hepatic synthetic source for any significant fraction of the blood protoporphyrin in erythropoietic protoporphyria is highly improbable. INTRODUCTION Congenital protoporphyria in humans was first named erythropoietic protoporphyria (EPP)' (1-3) based upon the large amounts of protoporphyrin IX (PP) found in the blood of patients with the disease which was thought to be synthesized in the bone marrow. However, the observation was made that the daily excretion of PP in the feces of these patients approached the total excess PP in the circulating erythrocyte mass. It was clear that this amount could not be derived from senescent erythrocytes only (4). Some investigators proposed the liver as an important additional source of PP in this disease. Acquired protoporphyria is extremely rare in man, but protoporphyria can be easily induced in mice with certain drugs, among which is griseofulvin (GF) (9-11). Murine protoporphyria induced by oral administration of GF has been used as an experimental model for human EPP (12,13). The site of excess PP synthesis in GF-induced murine protoporphyria (GFPP) is thought to be primarily, if not solely, hepatic (14). However, the concentration of PP associated with the circulating erythrocytes in GFPP can become comparable to that observed in EPP (9, 13, 14).We have developed spectrofluorometric techniques which give information about the binding sites of PP ...

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“…This major difference in clearances cannot be accounted for on the basis of mole cular weights (URO = 830.7, COPRO = 654.7) or by com parative water solubilities, since URO is more soluble than either COPRO or COPRO'GEN. Furthermore, differen tial affinities for plasma carrier proteins such as albumin and hemopexin offer no better solution since the associa tion of COPRO with these proteins has been shown to be stronger than that of URO [12]. It appears, therefore, that even in normal subjects most urinary COPRO is secreted into the tubular fluid after synthesis in the epithelial cells, with negligible amounts being filtered at the glomeruli.…”

Section: Clinical Researchmentioning

confidence: 97%