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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
PubMed1992

Childhood-onset familial porphyria cutanea tarda: effects of therapeutic phlebotomy.

Cutaneous fragility at age 2 years with blistering, scarring, milia, and hypertrichosis at age 4 years were noted in an otherwise healthy girl who had no family history of porphyria. Results of porphyrin analyses of urine, serum, and red blood cells revealed a pattern consistent with porphyria cutanea tarda. Red blood cell uroporphyrinogen decarboxylase activity was diminished to approximately 50% of normal in the child and in her mother and maternal grandmother, who were without symptoms; activity was normal in her sister, father, and maternal grandfather. Therapeutic phlebotomies were followed by a biochemical and clinical remission.

Bloodletting↗
PubMed1992

Distribution of erythrocyte free porphyrin content in erythropoietic protoporphyria.

Erythrocytes of patients suffering from erythropoietic protoporphyria (EPP) contain high levels of unchelated protoporphyrin IX (PP) molecules when they enter circulation, and the leakage of PP that leaks from the circulating cells is responsible for the patients' cutaneous photosensitivity. The level of PP in EPP blood has long been used as an indicator of the severity of the disease and is useful in its management. The present study investigates what additional information may be obtained by determining the distribution of the PP content of individual EPP red cells. Absorption and fluorescence images of fields of the dispersed and immobilized red cells from nine patients with EPP were acquired under computer control by use of an inverted fluorescence microscope equipped with a cooled slow-scan charge-coupled device camera. The distribution functions of the fluorescence emitted by individual red blood cells (IRBC) were derived by a suitable image analysis program and were converted to the distributions of the cellular PP content by relating the average value of the distributions (Iav) to the PP level of packed cells, as determined by an extraction assay. The IRBC distributions show that a small percentage of the red cells is responsible for most of the PP fluorescence, and the distributions of IRBC/Iav for the nine patients with EPP were found to be very similar. This is consistent with the leakage rate during circulation being approximately proportional to the cells' PP content.

Erythrocyte Membrane↗
PubMed1992

Skin care of the healed burned patient.

Many complications beset the skin formed over burn wounds, whether by primary re-epithelialization or grafting techniques, and these can evolve over days to decades. Mechanisms by which re-epithelializations, reattachment, and remodeling may result in skin prone to blistering, dryness, itching, contact dermititis, photosensitivity, and hypertrophic changes relatively early in the course of healing are considered, and therapeutic approaches are discussed. Late development of benign and malignant lesions calls for long-term surveillance of the healed skin of burned patients.

Burns↗
PubMed1991

Urinary porphyrin excretion in normal children and adults.

The relationship of random urinary porphyrin and creatinine values as functions of age and sex was examined in a normal population. Total urinary porphyrin was measured by a solvent extraction technique, while urinary creatinine was evaluated by an alkaline picrate method. Random urine specimens from 120 healthy patients (81 children and 39 adults) were evaluated. In both pediatric and adult populations, a strong correlation was found between urinary concentrations of porphyrin and creatinine (r = 0.7, P less than 0.0001). Urinary porphyrin excretion in mumol/mol creatinine (micrograms/g) was inversely related to both age (r = -0.59, P less than 0.0001) and weight (r = -0.61, P less than 0.0001) until approximately 9 years of age or 30 kg. Urinary porphyrin excretion in children 9 to 18 years of age was lower than that of younger children (P less than 0.0001) and approached adult values. Sex was not found to be a factor until 9 to 18 years of age, when females had higher urinary creatinine concentrations (P less than 0.05), but lower urinary porphyrin excretions (P less than 0.05) than similarly aged males. The converse was observed when similar values of adult women were compared with those of adult men. Men also had higher urinary porphyrin concentrations than women (P less than 0.01). Men had increased urinary creatinine concentration (P less than 0.05) and decreased porphyrin excretion ratios (P less than 0.05) when compared with males 9 to 18 years of age. Women had significantly lower urinary creatinine (P less than 0.001) and porphyrin (P less than 0.001) concentrations than females 9 to 18 years of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Cutaneous photosensitivity and coproporphyrin abnormalities in the Alagille syndrome.

Porphyria cutanea tarda-like blistering, fragility, and scarring of light-exposed skin was observed in four children with the Alagille syndrome. Abnormally elevated levels of serum porphyrins, of which coproporphyrin isomers I and III together accounted for 50%-89% of the total, were found in these four children but also in three other children with the Alagille syndrome without such skin lesions. The ratio for isomer I to III for total serum coproporphyrin concentration was determined in six cases; the concentration of isomer I was greater than or equal to that of isomer III in each case. Urinary total porphyrin excretion was found to be elevated in six of the seven cases, with 72% +/- 8% occurring as coproporphyrins I and III. The ratio for urinary coproporphyrin I to III was greater than or equal to 1 in six of these patients, the reverse of the typical normal isomer distribution. Inasmuch as the presence or absence of photocutaneous lesions did not correlate with levels of porphyrins in serum or urine, other factors may be involved in the pathogenesis of the skin lesions.

Adolescent↗
PubMed1989

Interaction of hemopexin, albumin and liver fatty acid-binding protein with protoporphyrin.

Equilibrium constants for the binding of protoporphyrin to serum albumin and hemopexin and liver cytosolic fatty acid-binding protein of the rat were determined fluorometrically. The experimental equilibrium constant [10(6) M-1 (mean +/- S.D.)] values were 8.4 +/- 1.3, 10.0 +/- 2.4 and 34.0 +/- 3.0 for albumin, hemopexin and liver fatty acid-binding protein, respectively. Statistical analysis showed the equilibrium constant of binding of protoporphyrin to liver fatty acid-binding protein to be significantly (p less than 0.01) higher than that to albumin and hemopexin. The data suggest that in patients with erythropoietic protoporphyria an equilibrium gradient may exist which favors the uptake by hepatocytes of plasma protoporphyrin as a result of its greater affinity for intracellular liver fatty acid-binding protein.

Animals↗
PubMed1989

Porphyrialike bullous dermatosis after chronic intense tanning bed and/or sunlight exposure.

Five fair-skinned patients had porphyrialike blisters and mechanical fragility of skin chronically exposed to intense radiation from tanning devices and/or the sun, but they had normal red blood cell, plasma, urine, and stool porphyrin levels. Use of several weak photosensitizing drugs during the year before or while developing lesions was identified or suspected in four patients.

Adult↗
PubMed1987

Hepatoerythropoietic porphyria: clinical, biochemical, and enzymatic studies in a three-generation family lineage.

Hepatoerythropoietic porphyria is caused by a marked deficiency in the activity of uroporphyrinogen decarboxylase, an enzyme that is essential for heme biosynthesis. It has been hypothesized that uroporphyrinogen decarboxylase deficiency is inherited as a homozygous defect in the disease. This suggestion has been supported by reports of a deficiency of the enzyme in parents of patients with the disorder. Further confirmation would be provided by demonstrating a similar uroporphyrinogen decarboxylase deficiency in the offspring of such patients. This study follows the enzymatic defect throughout three generations of a family in which a second-generation male was shown to have hepatoerythropoietic porphyria. Detailed biochemical and enzymatic analyses revealed a moderate deficiency of uroporphyrinogen decarboxylase in both the proband's parents and in his three children, all of whom were asymptomatic. The mildness of the clinical symptoms in the proband correlated with a higher level of residual enzyme activity than that in previously described patients. We conclude that clinically manifested hepatoerythropoietic porphyria results from the homozygous inheritance of a defect in the uroporphyrinogen decarboxylase gene, that the severity of clinical symptoms is probably related to the level of residual enzyme activity, and that the genetic defect of uroporphyrinogen decarboxylase in hepatoerythropoietic porphyria can be heterogeneous.

Adult↗
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↗