The porphyrias: a review

Analgesic Effect of Fortral (Pentazocine) in Acute Intermittent Porphyria

Five patients, all suffering severe abdominal pain in acute intermittent porphyria, were admitted to an investigation of the analgesic effect of Fortral (pentazocine) in this condition.

A single dose of Fortral was given daily to each patient at the time of severe abdominal pain and an attempt was made to use the smallest possible dose to achieve an analgesic effect. The analgesic effect produced was considered good in two cases and excellent in the remaining three cases. Pain ceased or decreased to a great extent within ten to twenty minutes of administration of Fortral. The drug appeared to act as rapidly when given orally as when given by intramuscular injection. The analgesic effect persisted from two to six hours, with an average of four hours.

In the doses of 50 mg three patients demonstrated side-effects which could be avoided by dividing the single dose into smaller ones.

In vitro catabolic effect of protoporphyrin IX in human osteoblast-like cells: possible role of the 18 kDa mitochondrial translocator protein

In several pathological conditions, when conversion of Protoporphyrin (PP)IX into heme is impaired, a toxic accumulation of PPIX might occur. PPIX has been found to have affinity to the mitochondrial Translocator Protein 18 kDa. Since it is known that TSPO is abundant in human osteoblast cells, thus we assumed that PPIX can affect cellular functions via interactions with TSPO in these cells. Therefore we aimed to study the metabolic responses of human osteoblast to a high (10⁻⁵ M) concentration of PPIX in vitro. We found that in primary culture of human osteoblast-like cells cell numbers decreased following exposure to PPIX(10⁻⁵ M). Cellular [¹⁸F]-FDG incorporation, mitochondrial mass, ATP content were suppressed, and ΔΨm collapsed. Lactate dehydrogenase activity was enhanced in culture media, indicating overall cell death, while no increase in apoptotic levels was observed. Cellular proliferation was not affected. Protein expression of TSPO, VDAC 1, and hexokinase 2 decreased, although the synthesis of mRNA for hexokinase 2 increased. Thus, PPIX(10⁻⁵ M) has a cytotoxic effect on human osteoblast-like cell in vitro. Since these cells remain viable following exposure to another TSPO ligand, PK 11195 (10⁻⁵ M), as observed previously by us, the mode of action of PPIX on osteoblast-like cells is not identical to that of PK 11195. Accordingly pathological accumulation of PPIX may cause necrosis of osteoblasts leading to bone mass loss. We show that this phenomenon is unrelated to iron overload.

Acute intermittent porphyria and epilepsy: safety of clonazepam

A young woman with acute intermittent porphyria (AIP) and juvenile myoclonic epilepsy began to have generalized tonic-clonic seizures (GTCs) at age 13. Subsequently, she had myoclonic seizures, which were often precipitated by visual stimulation, tended to occur in the morning, and sometimes evolved into GTCs. Valproate (VPA) resulted in a worsening of latent AIP, and treatment with a combination of phenytoin (PHT), carbamazepine (CBZ), and clonazepam (CZP) led to severe neuropathy of AIP and an electrolyte imbalance. These conditions were improved by water restriction, infusion of high doses of carbohydrates, and discontinuation of all antiepileptic drugs (AEDs) except for CZP. CZP appeared to be effective both in improving GTCs and myoclonic seizures and did not induce any symptoms of AIP. CZP may be porphyrogenic but can be used safely at a low dose for treatment of epilepsy in patients with AIP.

The possible role of ionic species in selective biodistribution of photochemotherapeutic agents toward neoplastic tissue

Photochemotherapeutic agents are photosensitizers that are selectively retained by neoplastic tissue. When tumor tissue containing these drugs is irradiated with visible electromagnetic radiation, the photosensitizing reaction may lead to tumor eradication, termed photodynamic therapy. Exogenous photosensitizers commonly used in clinical trials are mainly porphyrin derivatives. Phthalocyanines are currently being investigated as "second generation" photochemotherapeutic agents. The mechanism by which these photosensitizers are selectively retained in neoplastic tissue is unclear. This review examines the role of tissue and cellular pH as a factor in selective biodistribution. The pH values of normal and tumor tissue are summarized and the ionic species distribution diagram of porphyrins is presented. A two-fold mechanism of selective biodistribution is advanced, one involving normal tissue vs. tumor tissue selectivity, the other involving intracellular vs. intercellular distribution of sensitizer ionic species.

Case report of symptomatic porphyria cutanea tarda associated with histiocytic lymphoma

A fifth case is reported of symptomatic porphyria cutanea tarda (PCT) associated with lymphoma (of the histiocytic type) in a 45-year-old female. The PCT was documented in detail histologically and biochemically. The lymphoma was complicated by two paraneoplastic phenomena: inappropriate antidiuretic hormone secretion and peripheral neuropathy. It is possible that the PCT might also be a paraneoplastic phenomenon of the lymphoma. Search for an occult lymphoma may be of diagnostic and therapeutic value in patients presenting with PCT.

The laboratory evaluation of microcytic red blood cells

Microcytic red blood cell states are common clinical problems in both adult and pediatric age groups. The recent widespread availability of electronic blood cell counters for performing routine blood counts has increased the detection of microcytic red blood cells. Physicians must workup both symptomatic and asymptomatic patients with microcytic red blood cells before they can initiate proper therapy and/or counseling. The purpose of this review is threefold: (1) to discuss the causes of microcytic red blood cells in terms of disorders of decreased heme production vs. disorders of decreased globin production, (2) to review the clinical laboratory tests useful in differentiating microcytic red blood cell states, and (3) to present a practical approach for the laboratory workup of microcytic red blood cells.

Delta-Aminolaevulinic acid and amino acid neurotransmitters

The effects of the porphyrin precursor delta-aminolaevulinic acid (ALA) on gamma-aminobutyric acid (GABA) and L-glutamate transmitter systems was investigated in rat brain. It was found that ALA inhibited GABA and glutamate uptake and stimulated basal efflux of the amino acids in purified nerve endings. These effects were evident only at relatively high concentrations of ALA (at least 100 microM). Such concentrations probably do not occur in the nervous systems of patients suffering from acute porphyria. In addition, it was found that ALA inhibited the stimulated release of GABA from nerve endings probably by acting as an agonist at GABA autoreceptors. This effect was found at very low concentrations of ALA (1 microM). It is therefore likely that the neuropsychiatric manifestations of the acute porphyric attack are attributable, to some extent, to reduced GABA release at central synapses.

The effect of fluroxene [(2,2,2-trifluoroethoxy)ethane] on haem biosynthesis and degradation

Acute fluroxene treatment of male Wistar rats decreases the amounts of hepatic microsomal cytochrome P-450 and haem, increases the activities of hepatic delta-aminolaevulinate synthase and haem oxygenase, and increases the amounts of haem precursors (delta-aminolaevulinate and porphobilinogen) in the urine. All of the above effects of fluroxene are enhanced by pretreatment of the experimental animals with 3-methylcholanthrene and phenobarbital. The amounts of porphyrins in the urine and faeces were generally unaffected by acute fluroxene treatment of uninduced or 3-methylcholanthrene- or phenobarbital-induced Wistar rats. 2,2,2-Trifluoroethyl ethyl ether, the saturated analogue of fluroxene, did not affect the amounts of hepatic cytochrome P-450 and haem, the amounts of any of the haem precursors in the urine or faeces, or the activity of hepatic haem oxygenase in phenobarbital-induced male Wistar rats. The amounts of hepatic cytochrome P-450 and haem and of the haem precursors in urine and faeces, and the activity of delta-aminolaevulinate synthase, were generally not altered by acute fluroxene treatment of uninduced male Long-Evans rats. Chronic treatment of Wistar rats with fluroxene resulted in small increases in the amounts of delta-aminolaevulinate and porphyrins in urine. The amounts of porphobilinogen in urine were elevated up to 2000%, whereas the amounts of the porphyrins in faeces were generally unaffected. After chronic fluroxene treatment, the activity of delta-aminolaevulinate synthase was increased, whereas the activity of uroporphyrinogen synthase was decreased. It is concluded that acute fluroxene treatment may affect haem biosynthesis and degradation by a mechanism similar to allylisopropylacetamide, namely by stimulating an atypical cytochrome P-450-dependent pathway for haem degradation. The effects of chronic fluroxene treatment on haem biosynthesis may be a consequence of this mechanism or a result of the inhibition by fluroxene of uroporphyrinogen synthase. Chronic fluroxene treatment of male rats affects the haem biosynthetic pathway in a manner similar to that seen in human genetic acute intermittent porphyria.

The pathology of the liver in porphyria cutanea tarda

We report the findings in 53 biopsies from 45 patients with porphyria cutanea tarda (PCT). Red autofluorescence and birefringent acicular cytoplasmic inclusions were constant findings in all untreated cases. Autofluorescence occurs in other hepatic porphyrias, but acicular inclusions appear to be specific for PCT; we have seen them in subclinical porphyria and before development of cutaneous symptoms. They are probably uroporphyrins and they trend to disappear during rinsing by water during most staining procedures. We recommend unstained paraffin sections for their demonstration. Liver damage in PCT has features distinct from other liver diseases, including alcoholic liver disease. These include constant but mild periportal siderosis, focal lipofuscin deposition, focal lobular hepatocyte necrosis associated with groups of pigment-laden macrophages, focal steatosis, marked hepatocyte hyperplasia and the presence of periductal lymphocyte aggregates. The latter have not been previously described in PCT and were present in 43% of our cases. There is a direct relationship between increasing age and progressive distortion of liver architecture, with fibrosis present at a mean age of 48 years, cirrhosis at 57 and hepatocellular carcinoma at 66. The characteristic liver histology and the natural history of PCT are against this being the result of any non-specific liver damage and favour instead a specific liver disease whose pathogenesis may be mainly the result of the metabolic defect of PCT.

Demonstration of intracytoplasmic needle-like inclusions in hepatocytes of patients with porphyria cutanea tarda

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Diazinon and porphyria cutanea tarda

Cutaneous application of diazinon to rats over a period of 12 weeks gives rise to a condition biochemically indistinguishable from porphyria cutanea tarda. Faecal porphyrin levels are elevated with the appearance of isocoproporphyrin in the faeces. Oral administration of diazinon does not appear to cause any disturbance of porphyrin metabolism.

Optic atrophy in acute intermittent porphyria

A 24-year-old woman developed bilateral blindness after recovery from coma secondary to acute intermittent porphyria. Gradual return of vision in the right eye with a permanent unilateral visual field defect and optic atrophy followed. We believe the pathophysiologic mechanism was spasm of the vessels supplying the optic disk leading to ischemia and infarction of the optic nerve.

The differentiation of the porphyrias by means of high pressure liquid chromatography

The analysis of faecal and urinary porphyrins by high pressure liquid chromatography (H.P.L.C.) provides characteristic profiles and facilitates rapid diagnosis of variegate (porphyria cutanea tarda hereditaria), symptomatic porphyria (porphyria cutanea tarda symptomatica), hereditary coproporphyria, acute intermittent porphyria, erythro-hepatic protoporphyria and congenital porphyria (erythropoietic porphyria).

Erythropoietic protoporphyria. 10 years experience

The clinical and laboratory findings in 32 patients with erythropoietic protoporphyria as well as a review of the pertinent literature on this relatively recently described form of porphyria are presented. The disease is thought to be transmitted in an autosomal dominant fashion with variable penetrance and was characterized in these 32 patients by the onset in childhood of burning (97 per cent) and itching (88 per cent) of the skin on exposure to sunlight. This was accompanied by edema (49 per cent) and erythema (69 per cent) of the exposed areas. Vesicles, petechiae and residual scarring occurred less frequently. Associated abnormalities included cholelithiasis (12 per cent), anemia (27 per cent) and abnormal liver function studies (4 per cent). Reports of associated liver disease including nine cases of fatal hepatic failure, are reviewed. Current methods of diagnosis as well as theories of pathophysiology of the disease are presented. Nineteen of 23 of these patients recently treated with beta-carotene responded with significant increase in their tolerance to sun exposure.

Erythropoietic uroporphyria of Gunther first presenting at 58 years with positive family studies

Erythropoietic uroporphyria of Gunther was seen in a 58-year-old man who presented with photosensitivity, haemolytic anaemia, and classical laboratory findings. Family studies showed five asymptomatic relatives with erythrocyte uroporphyrin concentrations in the probable latent heterozygote range.

Ribosome function in livers of porphyric mice

1. A porphyrinogenic drug, 3,5-diethoxycarbonyl-1,4-dihydrocollidine, caused a decrease in the proportion of single ("run off") ribosomes, and an increase in the number of polyribosomes, in the livers of treated animals. 2. No change could be detected in the distribution of amino acid incorporation among hepatic polyribosomes.

Differentiation of porphyria cutanea tarda symptomatica from other types of porphyria by measurement of isocoproporphyrin in faeces

The faecal porphyrin patterns of 24 patients with porphyria cutanea tarda symptomatica (PCTS), eight patients with variegate porphyria, three patients with other types of porphyria, and 20 non-porphyrics subjects have been compared using a two-demensional thin layer chromatographic technique that separates porphyrins of the isocoproporphyrin series from other faecal porphyrins. The 'isocoproporphyrin': coproporphyrin ratio ranged from 0-1 to 5-6 for patients with PCTS, whereas in other types of porphyria and non-porphyric subjects it was 0-05 or less.

Repression by hematin of porphyrin biosynthesis in erythrocyte precursors in congenital erythropoietic porphyria

Hematin administered intravenously in a patient with congenital erythropoietic porphyria evidently entered erythrocyte precursors in the bone marrow, producing the well-known negative feedback repression of porphyrin biosynthesis with marked decline of porphyrin concentrations in urine, circulating plasma, and erythrocytes. A delay in the major segment of this effect corresponded roughly with the sum of the average transit times through the maturation compartments of the erythrocyte precursors. This delay was considerably longer than previously observed in the decline of porphyrin precursors after administration of hematin in patients with hepatic porphyria. The effect of hematin was compared with that of packed erythrocyte transfusions given at regular intervals in the same patient over a period of 2.5 years. In general, administration of hematin results in a reduction of porphyrin formation of the same order of magnitude, but of shorter duration, possibly in relation to the relatively small amounts of hematin infused.