Clearance times of porphyrin derivatives from mice as measured by in vivo fluorescence spectroscopy.

The clearance times of 17 different porphyrin derivatives from SKH:HR-1 mice have been measured using the technique of in vivo fluorescence spectroscopy. This technique monitors the in vivo porphyrin fluorescence observed from the external skin surface. Most hydrophilic porphyrin derivatives show relatively short clearance times, in the order of 2.5-6 h. The dicarboxylic acid porphyrins, proto-, hydroxyethylvinyldeutero- and hematoporphyrin IX have clearance times of 7.8, 12.2 and 14.7 h respectively. The mixture hematoporphyrin derivative has an intermediate clearance time of 12.6 h. N-methylated porphyrins show clearance times in the vicinity of 15-22 h. Monoaspartyl chlorin e6 shows the longest clearance time of all porphyrin derivatives measured (30.3 h).

Uroporphyrinogen I synthase from human erythrocytes: separation, purification, and properties of isoenzymes.

Uroporphyrinogen I synthase [porphobilinogen ammonia-lyase (polymerizing), EC 4.3.1.8] from human erythrocytes was separated into two active protein peaks (A and B on DEAE-cellulose, by ammonium sulfate fractionation, on Sephadex G-100, and on DEAE-Sephadex A-50 with a NaCl gradient. The final purification was 613 and 743 times for A and B, respectively. The corresponding yields were 2.2 and 3.4% Fraction A was separated further into two (A1 and A2) active protein bands and fraction B into three (B1, B2, and B3) on analytical polyacrylamide disc gel electrophoresis. Bands A1 and A2 were identical with B1 and B2; B3 represented a third isoenzyme. Molecular weights (mean +/- SEM), measured by gel filtration and sodium dodecyl sulfate/polyacrylamide gel electrophoresis, were 38,000 +/- 1000 for B1 and 40,000 +/- 1000 for B2 and B3. Isoelectric focusing on 4% polyacrylamide gel separated both fractions A and B into three active protein bands. Maximal activity of the enzyme was found in gel cuts (5-mm) at pH 5.6 for both fractions A and B.

Location of iron and porphyrin in the liver in porphyria cutanea tarda.

Porphyrin and iron distributions in the liver biopsies of patients with Porphyria cutanea tarda (PCT) were investigated by comparison of composite photographs from fluorescence microscope and after iron stain. Three distinct areas are visible: 1. red fluorescent areas with porphyrins; 2. blue areas corresponding to iron; 3. areas with neither iron nor porphyrin. The areas with iron or porphyrin do not overlap, therefore, this experiment indicates lack of direct correlation between iron and prophyrin distribution in livers of PCT patients.

Transitory renal failure following rapid administration of a relatively large amount of hematin in a patient with acute intermittent porphyria in clinical remission.

Transitory renal failure occurred in a patient with acute intermittent porphyria in clinical remission following i.v. administration of 1 000 mg hematin. The clinical and biochemical picture suggested "acute tubular necrosis", which was followed by a prompt and complete return of renal function without any late sequelae. The renal failure is thought to have resulted from the presence of circulating free hematin, formed as a result of rapid administration of such a relatively large amount. Such a complication has not occurred in patients given hematin for acute porphyric relapse, in whom much smaller amounts have been infused.

Effect and fate of intravenously administered porphobilin in rats.

In rats after i.v. porphobilin, blood pressure and pulse rate remained stable, the animals were calm and moved freely with no symptoms or signs of nervous effect. Porphobilin was rapidly excreted in the urine.

Porphyria variegata and porphyria cutanea tarda in siblings: chemical and genetic aspects (addendum).

A porphyria kindred in which the index case has porphyria variegata had also been shown to include a case of porphyria cutanea tarda, typical both from chemical and clinical features. The possibility that this was purely acquired rather than genetic seemed unlikely, but could not be wholly excluded. Recently, a niece of both of these cases, although asymptomatic, has been found to conform chemically with porphyria cutanea tarda, including the excretion of the isocoproporphyrin series, and thus represents the second case of this form of porphyria in this family. This strengthens the concept of genetic heterogeneity in this kindred and supports the suggestion of a double heterozygosity, as proposed in the primary paper [Watson, C.J. et al. (1975) Proc. Nat. Acad. Sci. USA 72, 5126-5129].

The activities of uroporphyrinogen synthetase and cosynthetase in congenital erythropoietic porphyria (CEP).

Normal or increased amounts of series III porphyrins with greater amounts of series I were observed on incubation of PBG in hemolysates of congenital erythropoietic porphyria vs. normal erythrocytes, human or bovine. Correlation with reticulocyte percentage was poor, in the aggregate a general trend toward increased values of both isomers I and III was noted with increasing reticulocytes. When the percent of type III was low the net amount was increased as compared with normal. Hemolysates of non-porphyric, reticulocyte-rich red cells (hemolytic or posthemorrhagic anemia) formed only minute amounts of type I porphyrin but at the same time no more, or even less type III than the porphyric hemolysates, although representing red cells of greater reticulocyte content. No evidence of deficient heme synthesis was observed in porphyric hemolysates incubayed with [14C]-porphobilinogen or 59Fe. Other studies of porphyric hemolysates incubated with and without added mouse spleen synthetase failed to reveal evidence of an absolute UPG-III cosynthetase (Co-S) deficiency. The large increases of type I porphyrin with normal or increased formation of type III, both in the disease and in the hemolysates, are believed due to a primary increase of ALA-S or UPG-S activity rather than a decrease of Co-S. Possible mutations which might be responsible for this increase are considered.

Porphyria variegata and porphyria cutanea tarda in siblings: chemical and genetic aspects.

A woman aged 54 was studied because of a severe acute porphyric (neurologic) relapse with clinical and chemical findings characteristic of porphyria variegata. During a family survey, her brother, aged 59, was found to have chemical abnormalities typical of porphyria cutanea tarda, without suggestion of neurologic manifestations. He had mild skin changes compatible with either of these forms of porphyria. The sister exhibited the protocoproporphyria of porphyria variegata, together with a large amount of fecal "x" porphyrin fraction, without demonstrable isocoproporphyrins. The brother had a uro-isocopro-type of porphyria in accord with the diagnosis of porphyria cutanea tarda, and quite at variance with the sister's findings. This occurrence of porphyria variegata and porphyria cutanea tarda in siblings is thus far unique. Certain hypotheses are considered in respect to genetic aspects of the differing prophyrias in this sibling pair.

Effects of hematin in hepatic porphyria. Further studies.

The present study was carried out in five cases of hepatic porphyria, including three of acute intermittent porphyria, one of variegate porphyria, and one of porphyria cutanea tarda in clinical remission. In two cases of acute intermittent porphyria (in relapse), a marked lowering effect on serum and urine porphobilinogen and delta-aminolevulinic acic was observed, together with prompt and gratifying clinical improvement. In a third case, in chemical remission but with longstanding psychoneurosis, no significant effects were noted, nor were any observed in the case of porphyria cutanea tarda. Although clinical improvements occurred in the case of variegate porphyria, the results were inconclusive for reasons given. Hematin was generally well tolerated. Preliminary reference is made to a transitory renal injury, without sequelae, where an excess of hematin was given in relation to time. Limits of tolerance are proposed. In the light of these observations the basic mechanism of the acute attack is diccussed.

On the existence of a mono-vinyl d-urobilin.

Chromic acid degradation of a d-urobilin, obtained after incubation of bilirubin in fecal bacterial cultures, gave methylvinylmaleimide and methylethylmaleimide. The d-urobilin, molecular weight 588, C(33)H(40)-N(4)O(6), clearly showed the presence of both vinyl and ethyl resonances in the nuclear magnetic resonance spectrum. These results point unambiguously to a urobilin structure with one vinyl and one ethyl beta-substituent.

Repression by hematin of porphyrin biosynthesis in erythrocyte precursors in congenital erythropoietic porphyria.

Hematin administered intravenously in a patient with congenital erythropoietic porphyria evidently entered erythrocyte precursors in the bone marrow, producing the well-known negative feedback repression of porphyrin biosynthesis with marked decline of porphyrin concentrations in urine, circulating plasma, and erythrocytes. A delay in the major segment of this effect corresponded roughly with the sum of the average transit times through the maturation compartments of the erythrocyte precursors. This delay was considerably longer than previously observed in the decline of porphyrin precursors after administration of hematin in patients with hepatic porphyria. The effect of hematin was compared with that of packed erythrocyte transfusions given at regular intervals in the same patient over a period of 2.5 years. In general, administration of hematin results in a reduction of porphyrin formation of the same order of magnitude, but of shorter duration, possibly in relation to the relatively small amounts of hematin infused.