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Biomedical subjects

M B Poh-Fitzpatrick

Publications and source records attributed to M B Poh-Fitzpatrick.

At least 55 records · Page 3Linked to original sources

Porphyria cutanea tarda. Diagnosis, management, and differentiation from other hepatic porphyrias.

Porphyria cutanea tarda is a photocutaneous syndrome characterized clinically by cutaneous fragility, bullae, hypertrichosis, pigmentary changes, and sclerodermoid plaques and characterized biochemically by hepatic overproduction and storage of excessive amounts of porphyrins. Porphyria cutanea tarda, the most common disorder of porphyrin metabolism, must be differentiated from variegate porphyria, hereditary coproporphyria, bullous dermatosis of hemodialysis, and drug-related pseudoporphyria.

Biopsy↗

Protoporphyrin metabolic balance in human protoporphyria.

Short-term maintenance of different stable steady state balances for protoporphyrin production, accumulation in erythrocytes and plasma, and fecal excretion was demonstrated in 5 patients with uncomplicated protoporphyria in whom red blood cell, plasma, and fecal protoporphyrin levels were determined on 5-7 sequential days. The patients were hospitalized in a research unit for dietary control and standardization of specimen collection. Each patient was found to quantitatively partition protoporphyrin among these compartments in a pattern that was reproducible from day to day, and characteristic for that patient. These observations partially substantiate a previously proposed hypothesis that protoporphyrin partitioning patterns may provide a criterion for prospective classification of these patients into groups that may ultimately be shown to have different risk for development of symptomatic liver disease.

Adult↗

Quinidine photosensitivity.

A 55-year-old woman developed a dermatitis confined to light-exposed areas while taking quinidine gluconate, warfarin sodium, furosemide, spironolactone, and digoxin after cardiac surgery. Phototesting indicated a normal erythematous response to 290- to 320-nm ultraviolet radiation, but she developed erythema from 6 joules/sq cm of 320- to 400-nm radiation (ultraviolet A [UV-A]), a much lower dose than needed to produce a reaction in normal individuals. Two days after she discontinued quinidine and warfarin, phototesting showed no reaction to as much as 20 joules/sq cm of UV-A. One week after resuming quinidine (but not warfarin), she again reacted to 8 joules/sq cm of UV-A. No reactivity was elicited when the preparation was applied to the skin or injected into the dermis either with or without subsequent UV-A irradiation.

Dose-Response Relationship, Radiation↗

Correlation of serum and urinary porphyrin levels in porphyria cutanea tarda.

A significant linear correlation was found between serum total porphyrin concentration and 24-hour total urinary porphyrin excretion in 18 patients with porphyria cutanea tarda sampled at diagnosis and during and after treatment on 73 occasions. This confirms that the serum porphyrin level parallels urinary porphyrin excretion and is an appropriate indicator of disease activity useful for monitoring patients in clinical practice.

Humans↗

Abnormally low UV-induced unscheduled DNA synthesis in cells from a patient with hydroa vacciniforme.

Skin fibroblasts from a patient with the photosensitive disorder hydroa vacciniforme were tested in vitro for DNA repair capacity. The rate of ultraviolet light (254 nm)-induced unscheduled DNA synthesis (UDS) in these fibroblasts was found to be 51-59% of the rate found in 4 normal fibroblasts strains. The patient had none of the clinical signs of the classic DNA deficient disease, xeroderma pigmentosum.

Adult↗

Absence of crystalline retinopathy after long-term therapy with beta-carotene.

The retinas of twenty-six patients with protoporphyria who had received treatment with beta-carotene for periods ranging from 1 to 10 years were examined for the presence of yellow crystalline deposits, similar to those recently reported in and around the maculae of individuals ingesting the related carotenoid compound canthaxanthin. No crystalline deposits were observed in any of our patients.

Adolescent↗

Hepatoerythropoietic porphyria: a variant of childhood-onset porphyria cutanea tarda. Porphyrin profiles and enzymatic studies of two cases in a family.

Hepatoerythropoietic porphyria is a rare variant of porphyria cutanea tarda, manifested clinically as photosensitivity starting in early childhood. Biochemically, there are elevated levels of protoporphyrin in erythrocytes and acetate-substituted porphyrins in the plasma, urine, and feces. Uroporphyrinogen decarboxylase activities in these patients are markedly suppressed. Thus far, only nine patients have been reported. We hereby describe the clinical manifestations, histologic changes, porphyrin profiles, and erythrocyte uroporphyrinogen decarboxylase determinations of two additional patients, 9-year-old and 7-year-old siblings, that are consistent with those of nine previously reported patients with hepatoerythropoietic porphyria.

Child↗

Activation of the complement system in patients with porphyrias after irradiation in vivo.

Irradiation of the forearms of two patients with erythropoietic protoporphyria and one patient with porphyria cutanea tarda resulted in an in vivo activation of the complement system, as assessed by diminution of the hemolytic titers of the third component of complement by 23-57%, and of the fifth component of complement (C5) by 19-47%. Such treatment also generated chemotactic activity for human polymorphonuclear cells; the chemotactic activity was stable at 56 degrees C and antigenically related to human C5. On Sephadex G-75 chromatography the chemotactic activity eluted with an apparent molecular weight of 15,000. These in vivo results extend our previous in vitro observation of photoactivation of complement in sera from patients with erythropoietic protoporphyria and porphyria cutanea tarda, and suggest that the complement system may participate in the pathogenesis of cutaneous phototoxicity in these patients.

Chemotaxis, Leukocyte↗

Elevated plasma triglyceride levels are associated with human protoporphyria.

Six patients with protoporphyria had mildly elevated triglyceride levels (200 to 300 mg/dl) on serum chemistry screening panels. Measurement of fasting plasma lipid profiles indicated that triglyceride levels were mildly elevated in 22 patients with protoporphyria compared with the values of a age- and sex-matched population of the Lipid Research Clinics prevalence study (p = 0.021). The effect of ingestion of the retinoid precursor beta-carotene on plasma triglyceride levels was assessed in 13 of these patients, both during carotene therapy and during therapy-free intervals. There was no significant increase in plasma triglyceride levels during administration of carotene; eight of 13 patients had lower levels during therapy. There was no significant correlation between plasma triglyceride levels at p less than or equal to 0.05 and serum carotene or blood protoporphyrin levels. Our results indicate that mild hypertriglyceridemia occurs with increased frequency in patients with protoporphyria, but not as a direct result of beta-carotene therapy.

Adolescent↗

Hydroa vacciniforme: induction of lesions with ultraviolet A.

Hydroa vacciniforme is a rare photosensitivity disorder with onset in childhood. The distinctive lesion is a vesicle which heals with scarring. We report a case of hydroa vacciniforme in which an abnormal minimal erythema dose to wavelengths of 322 to 370 nm within the ultraviolet A (UVA) range was demonstrated. Vesicles could be induced only with multiple exposures to UVA. Increased tolerance to UVA erythema was induced by multiple UVB exposures, although tanning was poor. Of note were the presence of several halo nevi and a history of the loss of ability to tan. The clinical features and appropriate laboratory evaluation of hydroa vacciniforme are reviewed.

Adult↗

Protoporphyrin hepatopathy. Effects of cholic acid ingestion in murine griseofulvin-induced protoporphyria.

Short-term effects of cholic acid ingestion on hepatic accumulation, fecal excretion, and blood levels of protoporphyrin were studied in vivo in griseofulvin-induced protoporphyric mice. Experimental mice that received feed with 2% griseofulvin and 0.5% cholic acid were compared with control mice that received feed with 2% griseofulvin for 4 wk. Five mice from each group were assessed each week for liver and blood porphyrin levels. Fecal protoporphyrin was compared weekly in the total pooled output of each population. Mean protoporphyrin levels were significantly lower for liver (P less than 0.0001), erythrocytes (P less than 0.05), and plasma (P less than 0.05), and higher for feces (P less than 0.001) for the mice that were fed cholic acid. Microscopic protoporphyrin deposits, inflammation, necrosis, and dysplasia were more severe in livers of control mice. A second experimental design compared four regimens in the feed given to all mice after 1-wk induction with 2% griseofulvin: (a) 0.5% cholic acid, (b) no adulterant, (c) 2% griseofulvin and 0.5% cholic acid, and (d) 2% griseofulvin. No difference in protoporphyrin removal from livers of mice in groups 1 and 2 was observed after 1 and 2 wk of these regimens. The apparent reduction in hepatic protoporphyrin content in mice of group 3 as compared with group 4 at weeks 2 and 3 was not significant at P less than 0.05. These data suggest that in selected circumstances, hepatic protoporphyrin secretion may be enhanced in protoporphyric disease states by bile salt supplementation.

Animals↗

A tightly bound protein-porphyrin complex isolated from the plasma of a patient with variegate porphyria.

Free acid porphyrins were isolated from plasma of a patient with variegate porphyria. Part of the total porphyrin content--which included protoporphyrin IX, harderoporphyrin and uroporphyrin in a molar ratio of 1.2:1:0.5 and traces of pentacarboxylic porphyrin--was extractable with ethyl acetate/acetic acid as described previously [1]. Unextractable porphyrins remained in the precipitate formed after mixing the lower liquid layer and precipitate from the extraction procedure (Fig. 1, [1]) with excess ethyl acetate/acetic acid. A portion of this precipitate was hydrolyzed in 8 mol/l HCl; its porphyrins were extracted with N-butanol and analyzed by high pressure liquid chromatography; another portion was chromatographed on Sephadex G-150 with 1 mol/l MgCl2, and the major porphyrin-protein pool was hydrolyzed in 8 mol/l HCl, reacted separately with AgNO3 and Ag2SO4, and subjected to cellulose acetate and polyacrylamide-gel electrophoresis. The results support the hypothesis that a dicarboxylic porphyrin, a major portion of which was unextractable by standard procedures [1] and which appeared to be covalently bound to a protein of approximately 68 000 mol. wt. that moved with human serum albumin during cellulose acetate electrophoresis, is the preponderant porphyrin in this plasma.

Carrier Proteins↗

Porphyrin levels in plasma and erythrocytes of chronic hemodialysis patients.

Plasma porphyrins and free erythrocyte protoporphyrins were measured in sixty-two chronic hemodialysis patients. Plasma porphyrins were significantly elevated in these patients and overlapped the lower portion of the range observed in twenty-four patients with porphyria cutanea tarda. Free erythrocyte protoporphyrins were moderately elevated in four patients. Overall, these values were not statistically different from values for a control group of specimens from fifty ambulatory dermatology patients. However, they were, on average, lower than the normal values previously determined for the method used.

Erythrocytes↗

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.

Adolescent↗

Cutaneous aspects of the porphyrias.

The clinical features of the porphyrias are often characteristic; and all can be definitively diagnosed by appropriate biochemical tests. Many of the cutaneous lesions are thought to be the result of photochemical damage which occurs due to 400 nm radiation exciting abnormally high concentrations of porphyrins in the skin. Others are probably based on hormonal or unidentified systemic factors. The effects of exogenous environmental porphyrinogenic agents have become increasingly well understood in recent years and at present treatment for many of the porphyrias is available. Early diagnosis, aided by recognition of the initial cutaneous signs and symptoms, is crucial for rapid implementation of appropriate therapy.

Coproporphyrins↗