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M B Poh-Fitzpatrick

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

83 records · Page 5Linked to original sources
PubMed1977

Rates of plasma porphyrin disappearance in fluorescent vs. red incandescent light exposure.

The rates of porphyrin disappearance in plasma specimens were assessed during exposure to standard fluorescent room lighting. Protoporphyrin half-life in specimens from patients with erythropoietic protoporphyria appeared to be less than 30 min under these conditions. Uroporphyrin-coproporphyrin mixtures in plasmas of patients with porphyria cutanea tarda were more photostable, with half-lives measurable in terms of hours. All plasma porphyrins could be protected for several days from similar photodegradation by performing all blood drawing, processing, and assay procedures under ordinary red-incandescent illumination, and by storage in the dark.

Blood Preservation↗
PubMed1977

Comparative study of protoporphyrins in erythropoietic protoporphyria and griseofulvin-induced murine protoporphyria. Binding affinities, distribution, and fluorescence spectra in various blood fractions.

Excess erythrocyte protoporphyrins of human congenital erythropoietic protoporphyria and of griseofulvin-induced murine hepatic protoporphyria were found to be associated with hemoglobin and stroma fractions in similar relationships. More than 99.5% of total erythrocyte protoporphyrin was bound to hemoglobin in each case. However, profound differences were found when protoporphyrin concentration was measured in erythrocytes that had been segregated into populations of progressive age on discontinuous density gradients. In erythropoietic protoporphyria, porphyrin content diminished rapidly with age; in murine protoporphyria, the aging erythrocyte populations became progressively more porphyrin rich. In vitro diffusion of protoporphyrin from plasma across the intact erythrocyte membrane was demonstrated. The equimolar binding affinity of protoporphyrin to hemoglobin was shown to be 40 times that of protoporphyrin to serum albumin. This strong affinity provides the driving force for the observed transmembrane diffusion, and explains the high erythrocyte/plasma porphyrin ratio in murine hepatic protoporphyria. The opposite rapid efflux of intra-erythrocytic protoporphyrin into plasma previously shown in uncomplicated erythropoietic protoporphyria occurs despite this strong hemoglobin affinity, implying continuous efficient clearance of protoporphyrin from plasma by the liver. Furthermore, these and other data suggest that a hepatic synthetic source for any significant fraction of the blood protoporphyrin in erythropoietic protoporphyria is highly improbable.

Animals↗
PubMed1976

Direct spectrofluorometry of diluted erythrocytes and plasma: a rapid diagnostic method in primary and secondary porphyrinemias.

Primary and secondary porphyrinemias are characterized by the presence of several porphyrin species in erythrocytes and/or plasma. Acid solvent extraction of porphyrins from natural ligands can preclude observation of significant spectral differences apparent on direct spectrofluorometric examination of porphyrin complexes in tissue. Erythrocytes and hemoglobin-free plasma obtained from 13 patients with erythropoietic, 9 with lead intoxication, 5 with porphyria cutanea tarda, 3 with iron deficiency anemia, 1 with erythropoietic porphyria, and 10 normal persons were simply diluted and analyzed spectrofluorometrically. Characteristic porphyrin-ligand spectral patterns were consistently obtained for each group of specimens, allowing diagnostic application of the data.

Anemia↗
PubMedDate not supplied

Cholic acid amelioration of light and electron microscopic hepatic lesions in experimental protoporphyria.

We studied the effects of cholic acid treatment on hepatic histology and ultrastructure in mice with griseofulvin-induced protoporphyria. After 5 weeks of feeding griseofulvin alone, control mice developed darkly pigmented livers which by light microscopy showed birefringent, brown pigment deposits in bile ducts and ductules, sinusoidal Kupffer cell aggregates, and occasionally in hepatocytes and bile canaliculi. Electron microscopy demonstrated aggregated protoporphyrin crystals at these sites as well as membrane blebs and reduction of microvilli in bile canaliculi. In contrast, experimental mice that were concomitantly fed cholic acid and griseofulvin developed no detectable pigment on light microscopy, only rare protoporphyrin crystals on electron microscopy and minimal bile canalicular abnormalities. This study suggests that protoporphyrin transport into bile is enhanced by cholic acid treatment and results in a significant reduction in hepatic protoporphyrin deposition and associated abnormalities of liver morphology.

Animals↗