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Biomedical subjects

M B Poh-Fitzpatrick

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

At least 37 records · Page 2Linked to original sources
PubMed1987

The porphyrias.

The porphyrias are a group of disorders of heme metabolism that result from partial defects in the several enzymes that control heme biosynthesis. Accumulation of porphyrins or porphyrin precursors in several different patterns results from these defects and biochemically characterizes each specific syndrome. Patterns of cutaneous photosensitivity and associated systemic symptoms among the several porphyrias result from the types of porphyrins or precursors accumulated in each.

Acute Disease↗
PubMed1986

Changes in protoporphyrin distribution dynamics during liver failure and recovery in a patient with protoporphyria and Epstein-Barr viral hepatitis.

Acute liver failure with cholestasis, histologic and serologic evidence of Epstein-Barr viral infection, and associated autoimmune hemolytic anemia occurred in a patient with lifelong protoporphyria. Changes in previously established baseline protoporphyrin distribution dynamics in erythrocyte, plasma, and fecal excretion compartments were observed during the period of severe hepatic dysfunction and recovery. These changes were consistent with predictions of a previously described conceptual model for human protoporphyria.

Acute Disease↗
PubMed1986

Molecular and cellular mechanisms of porphyrin photosensitization.

Mechanisms of porphyrin-sensitized photochemistry involving biomolecular substrates have been studied in a diverse array of in vitro and in vivo experimental protocols. Porphyrin-sensitized, singlet oxygen-mediated photooxidative damage has been implicated in peroxidation of cell membrane lipids; cross-linking of cell membrane and intracellular proteins; inhibition of cell membrane associated, cytosolic, mitochondrial and microsomal enzymes; disruption of intracellular organelles with release of inflammatory mediators and hydrolases; damage to DNA with retarded protein synthesis and delay in cell cycle; and activation of complement-generated inflammatory events leading to cell injury or death.

Cell Membrane↗
PubMed1986

The erythropoietic porphyrias.

There are two well-characterized disorders of porphyrin-heme metabolism in which the bulk of the porphyrins that accumulate in excess are formed chiefly within juvenile erythroid elements of the bone marrow. The first is most often termed congenital erythropoietic porphyria, and the second is most often termed erythropoietic protoporphyria. The former is a rare disorder, whereas the latter is one of the two most common porphyrias (along with porphyria cutanea tarda) and has a good probability of being encountered in general dermatologic practice. Both are determined genetically, cause cutaneous photosensitivity and systemic complications of importance, and are amenable to various forms of therapy.

Diagnosis, Differential↗
PubMed1986

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↗
PubMed1985

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↗
PubMed1985

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↗
PubMed1985

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↗
PubMed1985

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↗
PubMed1984

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↗
PubMed1984

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↗
PubMed1984

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↗
PubMed1984

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↗
PubMed1983

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↗