Porphyria properties

Certain disease states also produce alterations in the skin s optical properties. Alterations of the skin s surface, such as by psoriatic plaques, decrease transmitted fight. The effect may be lessened by application of oils whose refractive index is similar to that of skin (Anderson and Parrish, 1981). Disorders such as hyperbilirubinemia, porphyrias, and blue skin nevi result in increased absorption of visible light due to accumulation or altered distribution of endogenous chromophoric compounds. 

Only phenobarbital strongly induces the synthesis of the hepatic cytochrome P-450 drug metabolizing system. Phenobarbital is contraindicated in the treatment of acute intermittent porphyria. Buspirone lacks the anticonvulsant and muscle-relaxant properties of the benzodiazepines and causes only minimal sedation, v ... 

The gene mutation inhibits hydrolytic cleavage of fumarylacetoacetate into fumarate and acetoacetate. Consequently, the toxic precursors maleylacetoacetate and fumarylacetoacetate accumulate in the liver and kidneys. They possess a reactive double bond and can therefore react with macromolecules to assume the properties of alkylating substances. In addition, intracellular glutathione deficiency develops due to the stable complex formation with glutathione, favouring lipid peroxidations. Enhanced formation of 5-aminolaevulinic acid can also be observed during occasional attacks of acute intermittent porphyria (G. Mitchel et al., 1990). 

Now that we have considered the properties of ALA-synthetase, its synthesis and control, and the other factors that affect its activity, let us see how we may explain the symptoms of the hepatic porphyrias. There are two major forms of the disease acute intermittent porphyria (AIP) and porphyria cutanea tarda (PCT) [6,11]. In Table V are listed... 

Properties or Symptoms of Hepatic Porphyrias AND Interpretations of Their Causes"... 

The urine of acute porphyria patients develops a red color on standing. This substance called porphobilin arises spontaneouriy from PBG. Its absorption maximum is at 480 mp. Chemical properties suggest it is a condensation of two PBG to form a dipyrrylmethene derivative (7,106). 

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