Studies in porphyria. VII. Induction of uroporphyrinogen-I synthase and expression of the gene defect of acute intermittent porphyria in mitogen-stimulated human lymphocytes.

A 50% reduction in the activity of uroporphyrinogen-I (URO) synthase in liver, erythrocytes, and cultured skin fibroblasts characterizes all patients with clinically active acute intermittent porphyria (AIP). The same enzyme defect has also been demonstrated in the erythrocytes and skin fibroblasts of completely latent gene carriers of this disorder and presumably exists in the liver as well. In this study, we examined whether or not the formation of URO-synthase is impaired in AIP cells using lymphocytes treated with mitogens or infected with Epstein-Barr virus. Both mitogens (phytohemagglutinin and pokeweed mitogen) and Epstein-Barr virus induced the synthesis of URO-synthase in lymphocytes, but the induction of URO-synthase in AIP lymphocytes was only 50% as compared with that in normal lymphocytes. The impaired induction of URO-synthase in AIP lymphocytes reflects a specific gene defect because AIP lymphocytes showed normal [(3)H] thymidine uptake into DNA, [(3)H] uridine uptake into RNA, and normal delta-aminolevulinic acid (ALA) synthase, ALA-dehydratase, catalase activities, and heme content. Utilizing the same methodology, the ferrochelatase deficiency of hereditary erythropoietic protoporphyria could also be identified. The K(m) of the induced URO-synthase in AIP cells was identical to that of the enzyme in normal cells. The induced URO-synthase of mitogen-treated AIP lymphocytes was not accompanied by a concurrent enhanced level of ALA-synthase. Moreover, the URO-synthase deficiency in lymphocytes from actively ill AIP patients was not different from the level of enzyme activity when they were in clinical remission, or when compared with the enzyme activity of cells from completely latent AIP gene carriers. The results of this study indicate that the URO-synthase deficiency in AIP may be the result of a gene mutation regulating the rate of synthesis of a normal enzyme rather than a mutation causing a structural abnormality of this enzyme protein.

Studies in porphyria: functional evidence for a partial deficiency of ferrochelatase activity in mitogen-stimulated lymphocytes from patients with erythropoietic protoporphyria.

In this paper we show that the ferrochelatase defect in erythropoietic protoporphyria (EPP) can readily be identified in mitogen-stimulated lymphocytes since such cells from patients with EPP accumulate approximately twice as much protoporphyrin IX as cells from normal subjects when incubated with a porphyrin precursor, gamma-aminolevulinic acid (ALA). Treatment of cultures with ALA and with the iron chelator, CaMgEDTA significantly increased the level of protoporphyrin IX in mitogen-stimulated lymphocytes from normal subjects, while the same treatment failed to produce an increase in protoporphyrin IX in cell preparations from EPP patients. In contrast to the results with the chelator treatment, supplementation of the cultures with iron and ALA reduced the level of protoporphyrin IX in normal cells, but not in EPP cells. These findings are compatible with a partial deficiency of ferrochelatase in EPP lymphocytes. The gene defects of acute intermittent porphyria and hereditary coproporphyria have previously been identified using lymphocyte preparations from the gene carriers of these diseases. The present study demonstrates that EPP represents another form of human porphyria in which the gene defect of the disease can now be identified in lymphocyte preparations.

Assay of contact photosensitivity to musk ambrette in guinea pigs.

This study reports the induction of contact photodermatitis to musk ambrette, 2-methoxy-3,5-dinitro-4-methyl-t-butylbenzene, in guinea pigs. Photoallergic contact dermatitis was assayed using 2 alternative induction methods. Successful photosensitization was achieved only when the nuchal skin was stripped with scotch tape before application of musk ambrette and ultraviolet radiation. Induction methods utilizing nonstripped nuchal skin which induce photosensitivity to potent photoallergens were ineffective for musk ambrette. Phtotoxicity tests to musk ambrette at concentrations between 1 and 50% and a dose of 10.2 joules/cm2 from "Black Light" fluorescent tubes were all negative. Under identical irradiation conditions, anthracene at 0.9% and 8-methoxypsoralen at 1% were consistently positive. The mechanism of photosensitivity to musk ambrette appears to be photoallergic rather than phototoxic. The requirement for skin abrasion to induce photosensitization parallels the clinical reports of photosensitivity to musk ambrette in man.

Infestation by Tunga penetrans.

Infestation by the flea Tunga penetrans, although quite prevalent in Central America, South America, and Africa, is rarely recognized or reported in North America. This report describes a case of tungiasis occurring in a New York resident who acquired the disease in Africa. The patient manifested characteristic lesions of white papules with central black pits on the dorsa of her toes. Treatment consisted of removal of the offending parasites.

Induction of drug photosensitization in man after parenteral exposure to hematoporphyrin.

Two patients had acute phototoxic reactions after intravenous injections of hematoporphyrin (7 mg/kg) and exposure to light. These reactions were characterized by pain, redness, and swelling of affected sites. Controlled clinical studies were instituted using known types and amounts of light to ascertain the degree of photosensitivity at various time intervals after drug administration. In addition, action spectrum studies elicited a peak response at 405 nm (+/- 5 nm). Plasma hematoporphyrin concentration was approximately 520 microgram/100 ml one hour after hematoporphyrin infusion and it gradually declined during a period of 42 days with a biphasic diminution that suggested the existence of at least two pools of hematoporphyrin with half-life decay times of 16 hours and 12 days. beta-carotene was administered to ascertain whether or not the phototoxic response could be modified. It is suggested that a degree of protection was obtained that was insufficient to protect the patient.

Cutis marmorata telangiectatica congenita: clinicopathologic characteristics and differential diagnosis.

Cutis marmorata telangiectatica congenita is an uncommon cutaneous vascular disorder characterized by persistent cutis marmorata, telangiectases, and phlebectases. In addition to atrophic and/or ulcerated lesions, other vascular conditions may be observed. Cutis marmorata telangiectasia congenita usually occurs sporadically, typically is present at birth, and predominantly affects girls. Various associated congenital anomalies have been reported in approximately half of the patients with this condition.

Bilateral tinea nigra plantaris and tinea nigra plantaris mimicking melanoma.

Tinea nigra, a superficial fungal infection caused by Phaeoannellomyces werneckii, presents as a hyperpigmented, nonscaling macule of variable size and shape. Typically lacking induration, erythema, or pruritus, these "ink spot" lesions may resemble junctional nevi or malignant melanoma. Rapid, noninvasive diagnosis can be provided by potassium hydroxide examination, demonstrating numerous large, dematiaceous hyphae.

Tinea pedis masking a Kaposi's sarcoma.

A 67-year-old white man presented with bilateral blancing erythema and scale of the second through fifth toes extending on to the dorsa and moccasin areas of the feet for two years. The right great toe had subungual debris. No cultures or KOH studies were recorded. A course of tolnaftate cream therapy was initiated. Two years later, the patient returned and complained of no change in his condition. Previously recorded descriptions and diagrams in the medical record confirmed his report. At this time, KOH preparations from the skin and nail were positive for hyphae. He refused to accept medical recommendations for a fungal culture and griseofulvin therapy. He, therefore, was instructed to use miconazole cream twice daily as alternative treatment. One year later, physical examination was unchanged. KOH preparations and fungal cultures of the skin were twice negative. A 4-mm punch skin biopsy specimen of the erythematous patch on the dorsum of the foot was performed. Hematoxylin and eosin-stained sections revealed a proliferating vascular process in the cutis. Many spindle-shaped cells formed vascular slits and endothelial-lined spaces in which there were erythrocytes. No hyphae were seen. One year after the biopsy specimen was taken, the erythema of his feet persists, and a few nonblanching nodules are visible. He declined further studies.

Studies in porphyria IX: Detection of the gene defect of erythropoietic protoporphyria in mitogen-stimulated human lymphocytes.

We have demonstrated in this study that mitogen-stimulated lymphocytes from EPP subjects accumulate substantially greater amounts of protoporphyrin IX than do normal lymphocytes when incubated with ALA. Protoporphyrin IX formation by normal lymphocytes is stimulated by CaMgEDTA, an inhibitor of ferrochelatase, and is decreased by ferrous iron which facilitates the utilization of protoporphyrin IX for heme synthesis. In contrast, protoporphyrin IX formation by EPP lymphocytes is less stimulated by CaMgEDTA than is the case with normal lymphocytes and is only slightly affected by iron. Clinically manifested EPP subjects and completely latent gene carriers of EPP can be identified using this lymphocyte culture technique. The data from this study provide clear evidence of a functional deficiency of ferrochelatase activity in human EPP lymphocytes. EPP thus represents the third of the three dominant porphyric disorders of man, including acute intermittent porphyria and hereditary coproporphyria, which can now be diagnosed using lymphocytes.