Abnormal Porphyrin Metabolism in Diseases Other Than Porphyria

Increased urinary coproporphyrin excretion observed in patients with differently staged Hodgkin's disease treated with chemotherapy

It has been reported that patients with Hodgkin's disease (HD) show altered porphyrin metabolism, and suggested that the cause is the neoplastic process itself. If this is true, disease progression should be associated with higher levels of porphyrin excretion. The aim of this study was to evaluate urinary coproporphyrin levels in patients with Hodgkin's disease at different stages. As many of the patients received chemotherapy, another aim was to verify experimentally whether chemotherapeutic agents might increase porphyrin levels in rabbits. All of the patients had above-normal urinary coproporphyrin levels. On the other hand, rabbits receiving the porphyrin precursor 5-aminolevulinic acid (5-ALA), and also treated with doxorubicin, showed very high plasma porphyrin levels. The increased levels of urinary coproporphyrins seem to be due to the disease itself, since the patients in stages III and IV had higher excretion values, presumably due to biochemical heme synthesis lesions that lead to the availability of the porphyrin precursor, as well as coproporphyrin accumulation and excretion. The altered porphyrin synthesis may be attributable to the cytotoxic oxygen species generated in the presence of NADH and iron. As the patients also received extensive chemotherapy regimes, the altered porphyrin metabolism may be affected by antineoplastic treatment generating oxygen reactive radicals. The alterations in porphyrin metabolism induced by chemotherapeutic agents appear to be demonstrated in rabbits in which doxorubicin increases porphyrin synthesis after porphyrin precursor treatment.

[Anemia secondary to lead poisoning. Our experience with 12 cases]

BACKGROUND

A decrease in hemoglobin production is probably the main cause of anemia observed in patients poisoned by lead although hemolysis caused by the effects on membrane or by inhibition of other enzymes such as 5'-pyrimidine nucleotidase may also play a key role. The main lead exposure source comes from lead use in industry; however, outside occupational exposure, food and water consumption is the main cause of lead exposure.

MATERIALS AND METHODS

Clinical and analytical characteristics are reported of twelve patients with lead poisoning of food and water source occurred in the last 14 years in two health areas in north Extremadura.

RESULTS

The exposure source was wine, vinegar and olives in one case, hand-made brandy in five, water consumption in houses with lead piping, and in two cases the cause was not determined. The clinical picture was similar in all cases with the exception of one female patient who had encephalopathy and hepatic failure. Diagnosis was suggested by regenerative anemia with basophilic stippling of erythrocytes. All patients received oral calcium disodium EDTA.

CONCLUSIONS

Lead poisoning in non-industrial areas is a rare entity. Nevertheless, owing to the use of artisanal procedures for wine elaboration and derivatives, its occurrence is increasing. In a patient with symptoms of lead poisoning and regenerative anemia, a peripheral blood smear should be reviewed.

Analysis of urinary porphyrins in rats exposed to aluminum and iron

The mechanism by which excess aluminum induces anemia may be aluminum overload resulting from a reversible block in heme synthesis due either to a defect in porphyrin synthesis or to impaired iron utilization. Studies were conducted to define the specific changes in the urinary porphyrin excretion pattern (porphyrin profile) and the time course of those changes in rats exposed to aluminum. In these studies, aluminum chloride (AlCl3) was orally administered to female Wistar rats at the dose of 100 mg Al/kg for 35 days with or without FeCl2 (4 mg Fe/kg). Control rats were treated with 0.9% NaCl or with FeCl2 (4 mg/kg). The dynamics of urine porphyrins (8-, 7-, 6-, 5-, and 4-carboxyporphyrins) was determined by HPLC on the 7th, 14th, 21st, 28th, and 35th days in both exposed and control groups of rats. The results of the experiment indicate that aluminum induced a statistically significant increase in the percentage of uroporphyrin and a decrease in coproporphyrin in urine (cumulative dose, 2100 mg Al/kg). Changes in urinary porphyrins were observed when the concentration of aluminum in serum was at 48 microg Al/L on average. Administration of iron together with aluminum diminished the described changes in porphyrins metabolism caused by aluminum itself.

Interaction of aluminum with exogenous and endogenous iron in the organism of rats

The aim of these experiments was to find changes in free erythrocyte protoporphyrins (FEP) and in the concentration of endogenous iron in the blood, erythrocytes, serum, liver, kidneys, and spleen of rats, as well as in the dynamics of aluminum concentrations in the serum of rats after oral application of aluminum chloride (AlCl(3)) separately or with ferrum chloride (FeCl(2)), depending on the time and doses administered. The experiments were carried out on female Wistar rats which received (p.o.) 100 mg Al/kg separately or with iron (4 mg Fe/kg) daily for 35 days. The effects of aluminum administration were noticed after the second week. The experiments demonstrated that the increase in the level of free erythrocyte protoporphyrins in the blood is the most sensitive indicator of exposure to AlCl(3). A decrease in iron concentration in erythrocytes, blood, and spleen was also noticed. The response and the sequence of the investigated effects were recorded according to aluminum and iron concentration in the serum. Joint administration of iron and aluminum decreases concentration of aluminum in serum and prevents changes in the investigated indicators in rats exposed to aluminum chloride.

The ratio of erythrocyte zinc-protoporphyrin to protoporphyrin IX in disease and its significance in the mechanism of lead toxicity on haem synthesis

Protoporphyrin and zinc-protoporphyrin were measured in the erythrocytes of normal subjects, workers exposed to lead and patients with iron deficiency and erythropoietic protoporphyria (EPP). Results showed significantly higher levels of zinc-protoporphyrin in the lead-exposed workers (P < 0.0001), patients with iron deficiency (P < 0.0001) and EPP patients (P < 0.001) compared with normal subjects. The lead-exposed workers showed the highest levels of zinc-protoporphyrin, which were significantly greater than both the iron-deficient and EPP patients (P < 0.0001). They also showed a higher ratio of zinc-protoporphyrin to free protoporphyrin compared with normal subjects (P < 0.0001) but no significant difference in this ratio was found when compared with iron-deficient patients (P = 0.1). These results are discussed in light of the controversy concerning the mechanism of formation of zinc-protoporphyrin in lead exposure.

Neonatal bullous eruption as a result of transient porphyrinemia in a premature infant with hemolytic disease of the newborn

We describe the clinical and biochemical features of an infant with marked transient porphyrinemia in whom blistering developed while the infant was undergoing phototherapy for severe Rh isoimmunization. The cause of the transient porphyrinemia was likely to be multifactorial--abnormal porphyrin metabolism or accumulation in a premature infant with multisystem disease and multiple drug therapy. In addition, the infant received an unusually large amount of phototherapy. No evidence for an associated porphyria has been obtained. We believe this is a unique case because transient porphyrinemia associated with neonatal blistering does not appear to have been reported previously. Furthermore, blistering associated with phototherapy is rare.

Erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is an inherited inborn error of porphyrin metabolism caused by decreased activity of the enzyme ferrochelatase, the terminal enzyme of the haem biosynthetic pathway, which catalyses the insertion of iron into protoporphyrin to form haem. EPP is characterized clinically by photosensitivity to visible light commencing in childhood, and biochemically by elevated red cell protoporphyrin levels. Although the majority of papers and reviews have classified EPP as an autosomal dominant disorder, the inheritance has now been shown to be more complex, and both autosomal dominant and recessive patterns of inheritance have been demonstrated using ferrochelatase activity. Further molecular studies should clarify the exact mode of inheritance. It seems likely that in the majority of families a defective allele from the apparently normal parent will be required for disease expression, but another possibility is autosomal dominant inheritance with low clinical penetrance. Exposure to bright sunlight, for as little as a few minutes in the worst affected patients, causes burning pain in exposed skin, which may be so severe and persistent that it prevents sleep for several nights. Patients usually attempt to relieve the pain by cold water or cold compresses. Apart from sun avoidance, the mainstay of prophylactic treatment has been beta-carotene. Although the published evidence for the effectiveness of beta-carotene is impressive, no controlled trials using adequate doses have been performed to unequivocally confirm its usefulness. The most serious complication of EPP is acute hepatic failure, which is due to accumulation of protoporphyrin in the liver. If jaundice develops, a rapidly fatal outcome often follows, unless liver transplantation is undertaken. Regular monitoring of liver function and red cell porphyrin levels is advisable, but this does not always identify patients before serious liver damage has occurred. Even when patients are identified at an early stage in the development of liver disease the therapeutic options available to prevent further damage are limited, and have not been fully evaluated. The gene for ferrochelatase has been cloned, sequenced and mapped to the long arm of chromosome 18. As mutations continue to be identified, phenotype/genotype correlations should become apparent, and it may eventually be possible to identify those patients at risk of developing hepatic failure. In addition, as the basic enzymatic defect in EPP is at the level of the bone marrow stem cells, which are the target cells of choice in the development of retroviral-mediated gene transfer, definitive treatment of EPP by gene therapy is a distinct hope for the future.(ABSTRACT TRUNCATED AT 400 WORDS)

Some parameters of haem synthesis in dialysed and non-dialysed uraemic patients

Some parameters of haem synthesis were estimated in 60 uraemic patients (30 non-dialysed, 30 dialysed) and in 30 matched controls. Serum delta-aminolaevulinic acid and erythrocyte coproporphyrin and protoprophyrin were found significantly higher in the non-dialysed uraemics than in the controls. Erythrocyte delta-aminolaevulinic acid dehydrase (ALA-D) activity was 498 +/- 174 mumol/h.l in the non-dialysed patients, 321 +/- 146 in the dialysed (just before haemodialysis) and 833 +/- 281 in the healthy controls, the differences between these groups all being statistically significant (p less than 0.001). After haemodialysis the enzymic activity in the dialysed group increased significantly (380 +/- 167, p less than 0.001), but remained lower than normal (p less than 0.001). A similar pattern - although with less statistical significance of the differences between groups - was observed concerning erythrocyte uroporphyrinogen I synthase activity. Incubation of normal erythrocytes with uraemic plasma resulted in a considerable decrease of their ALA-D activity (from 830 +/- 263 to 616 +/- 126) while incubation of uraemic erythrocytes with normal plasma increased their ALA-D (from 384 +/- 139 to 494 +/- 77). Addition of zinc in the haemolysate caused a similar induction of ALA-D in both controls and uraemics. The zinc-induced uraemic ALA-D practically reached normal levels. The mechanism of enzymic depression and the possible role of elevated delta-aminolaevulinic acid concentrations (to which depressed ALA-D activity considerably contributes) in the pathogenesis of the neurologic manifestations of uraemia, are discussed.

Direct fluorometric determination of erythrocyte free and zinc protoporphyrins in health and disease

Precise estimation of erythrocyte non-iron fluorescent protoporphyrins in conditions where small variations in their level are involved is experimentally difficult. We used a highly sensitive fluorometric procedure which provided, in a single direct measurement, the differential estimation of the levels of free (FPP) or zinc (ZPP) protoporphyrins relative to the hemoglobin (Hgb) concentration in diluted blood samples. With use of an internal calibration procedure, the levels of ZPP and FPP in normal healthy donors were found to be 2.7 +/- 0.9 and 0.20 +/- 0.08 micrograms/g Hgb, respectively. In blood samples taken from patients suffering from acute inflammatory processes the mean ZPP level was twofold higher, and the mean FPP was four times higher, than the normal level, suggesting better sensitivity of the FPP measurement for the detection of minor influences on the hemopoietic system. In a variety of non-inflammatory diseases FPP was less but still significantly above normal level. No significant correlation was found between the levels of both protoporphyrins and Hgb concentrations in all the groups of normal donors and patients examined.