Descripción: 1. 1. A family investigation was performed in eleven cases of Porphyria Cutanea Tarda (PCT). 2. 2. By using clinical findings, quantitative measurements and thin layer chromatography (TLC) of urinary porphyrins, overt and subclinical PCT patients have been identified. 3. 3. In the overt type, skin manifestations are present, excretion of urinary porphyrins is increased and the TLC pattern of porphyrins in urine is characteristic for PCT. 4. 4. In the subclinical type, patients have no clinical symptoms, excretion of porphyrins in urine might be normal or enhanced and TLC pattern of urinary porphyrins is typical for PCT. 5. 5. By applying these criteria a clear distinction between hereditary and non-hereditary PCT was possible. 6. 6. Among the 11 families studied, in four families where PCT was hereditary, four members have the overt type and ten relatives the subclinical type. 7. 7. In seven families where PCT was non-hereditary only the propositus has overt PCT and not a single relative showed any clinical or biochemical abnormality. © 1980.

Descripción: 1. 1. The porphyrinogenic ability of several antineoplasics used in the therapy of the different cancers was evaluated. The action of cyclophosphamide, busulfan and 5-fluorouracil on the amount and nature of the accumulated hepatic porphyrins and on the activity of δ-aminolaevulinate synthase(ALA-S). were estimated at different doses and times of drug treatment in 17-day-old chick embryos. 2. 2. It was observed that cyclophosphamide produces a significant increase in the accumulation of hepatic porphyrins at different doses as well as in the activity of the ALA-S, at all the incubation times. Cyclophosphamide alters the pattern of porphyrins accumulated in the liver, where a coproporphyrin: protoporphyrin ratio higher than in the controls can be observed. 3. 3. Busulfan increased the hepatic porphyrins accumulated in the liver but to a lesser degree than cyclophosphamide. 4. 4. 5-Fluorouracil did not modify the hepatic porphyrin content when it was administered at doses up to 40 mg/embryo. 5. 5. When the embryos were injected with busulfan or 5-fluorouracil no significant differences were observed in the activity of ALA-S up to 11 hr of incubation. 6. 6. These results indicate that cyclophosphamide has a remarkable porphyrinogenic capacity in chick embryo while busulfan. notwithstancling the fact that it alters the haem pathway, it does so to a degree that does not impair the regulation of ALA-S activity. Fluorouracil seems to be non porphyrinogenic in this system, up to 40 mg/embryo. © 1988.

Descripción: 1. 1. The effects of light and porphyrins on the activity of red cell uroporphyrinogen decarboxylase were studied. 2. 2. Photoinactivation of uroporphyrinogen decarboxylase was dependent on uroporphyrin concentration, irradiation time and temperature. Using 40 W/m2 of UV light intensity, 40-45% decreased activity was produced with 200 μM uroporphyrin I, at 37°C and after 2 hr of illumination. 3. 3. It has been demonstrated that porphyrins photoinactivate uroporphyrinogen decarboxylase and a mechanism for this action in relation to skin lesions is proposed. © 1986.

Descripción: The use of 5-aminolaevulinic acid (ALA) is gaining increasing attention for photosensitization in photodynamic therapy of superficially localized tumours. The aim of this work was to determine the kinetics of porphyrin generation in tissues after topical application of ALA delivered in different vehicles on the skin overlying the tumour and normal skin of mice. Maximal accumulation was found in tumour 3 h after ALA application in both cream and lotion preparations. Normal and overlying tumour skin tissues showed different kinetic patterns, reflecting histological changes when the latter is invaded by tumour cells. Liver, kidney, spleen and blood porphyrins also raised from basal levels, showing that ALA and/or ALA-induced porphyrins reach all tissues after topical application. During the first 24 h of ALA topical application, precursors and porphyrins are excreted by both urine and faeces. ALA lotion applied on the skin overlying the tumour induced higher accumulation of tumoural porphyrins than cream, and lotion applied on normal skin appeared to be the most efficient upon inducing total body porphyrins. This work has demonstrated the great influence of the formulation of ALA vehicle on penetration through the skin. Knowledge of the kinetics of porphyrin generation after different conditions of ALA application is needed for the optimization of diagnosis and phototherapy in human tumours.

Descripción: 1. 1. The activity of the following enzymes involved in the biosynthesis of porphyrins was determined in endosymbiote-free and endosymbiote-containing Crithidia deanei grown in a chemically defined medium: succinyl Coenzyme A synthetase (Suc.CoA-S), 5-aminolevulinate synthetase (ALA-S), 4,5-dioxovaleric acid transaminase (DOVA-T), 5-aminolevulinate dehydratase (ALA-D), por- phobilinogenase (PBGase), deaminase and heme synthetase (Heme-S). The amount of 5-aminolevulinic acid (ALA) and porphobilinogen, porphyrins and heme was also determined. 2. 2. ALA and PBG were detected in C. deanei. The levels of free porphyrins was low. Heme concentration was nil. 3. 3. The activity of ALA-D. deaminase and PBGase was not detected in C deanei. 4. 4. The activity of Suc.CoA-S and ALA-S were twice higher in symbiote-containing than in aposymbiotic C. deanei. Aposymbiotic cells had a higher activity of DOVA-T than symbiote-containing cells. 5. 5. The level of Heme-S, measured using protoporphyrin as substrate, was twice as high in symbiotecontaining than in symbiote-free cells,. © 1985.

Descripción: Medical and biochemical analysis were performed on 58 patients with chronic alcoholism. In accordance with medical characterisation, patients were divided in three groups: A (patients having only hepatopathy), B (patients with hepatopathy and neuropathy) and C (patients having only alcoholic neuropathy). Simultaneously, several parameters related to heme biosynthesis were examined. Urinary delta-aminolevulic acid (ALA), porphobilinogen (PBG) and porphyrins and fecal porphyrins measurements did not show significant difference among all studied groups. The activities of ALA-dehydratase (ALA-D), uroporphyrinogen-I-synthase (URO-I-S) and uroporphyrinogen-III-synthase (URO-III-S) were monitored in peripheral erythrocytes. From the enzymes measured, only ALA-D levels in groups B and C were significantly depressed (p < 0.002) compared with normal subjects. The decrease in ALA-D correlated with the degree of neuropathy.

Descripción: 1. 1. Effects of various factors on chlorophyll, porphyrin and protein content, growth and on the activities of the enzymes involved in the earlier stages of tetrapyrrole synthesis, in cultured soybean cells, were studied. 2. 2. When dark-grown callus was exposed to light, it was found that the amount of porphyrins formed was not altered, but chlorophyll content as well as Succinyl CoA Synthetase (Suc.CoA-S), Aminolevulic Acid Synthetase (ALA-S), Aminolevulic Acid Dehydratase (ALA-D) and Porphobilinogenase (PBGase) activities increased. 3. 3. Addition of Aminolevulic Acid (ALA) to the medium culture, was found to stimulate porphyrin accumulation and to prevent growth; however chlorophyll content was not significantly modified. ALA-S was inhibited while both ALA-D and PBGase activities were enhanced. The action of puromycin and mitomycin added along with ALA to the media, was also studied, but neither of these inhibitors modified much the effects produced by ALA. 4. 4. Addition of Porphobilinogen (PBG), showed accumulation of uroporphyrin in the tissue; except inhibition of ALA-S, enzymes activities, protein and chlorophyll content were not modified. Evidence obtained would indicate that callus tissue was not permeable to PBG. 5. 5. Omission of iron from the culture medium, produced porphyrin accumulation and prevented growth. It has been consistently found that, the higher the content of porphyrins, the less the callus growth. Coproporphyrin was the major component of the porphyrins formed in ALA supplemented or iron deficient media. ALA-S and ALA-D were reduced under iron deficiency. 6. 6. The addition of ATP to the media, did not affect porphyrin, protein, and chlorophyll synthesis, growth or ALA-D, but Suc.CoA-S, ALA-S and PBGase activities diminished. 7. 7. Gibberelic acid produced a measurable increase of PBGase, while diminished Suc.CoA-S and ALA-S. 8. 8. Succinate increased growth and inhibited ALA-S and ALA-D. 9. 9. Carbonyl cyanide m-chlorophenyl hydrazine (CCCP), added to the medium produced accumulation of porphyrins, consequently, ALA-S was greatly inhibited and growth prevented. PBGase was also diminished. 10. 10. Coproporphyrinogenase and Decarboxylases activities were hardly detected in most experiments, and are limiting. 11. 11. The complex pattern of results obtained is discussed. © 1975.

Descripción: Fil:Tigier, H.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: 1. 1. The present work undertakes a comparative study on the hexachlorobenzene (HCB) porphyria induction in female rats of Wistar and CHBBTHOM strains. The purpose was to characterize the CHBBTHOM strain with respect to the haem metabolic pathway, its regulatory mechanisms and its response to foreign drugs. 2. 2. After 7 weeks of treatment it was observed that the hepatic porphyrins increased 140 times, ALA-synthase 4 times and PCL was 73% inhibited in the Wistar strain. 3. 3. On the other hand the animals of CHBBTHOM strain showed lesser alteration on these parameters; hepatic porphyrins increased only 3-fold, ALA-synthase 1.7-fold and PCL was only 22% inhibited. 4. 4. Total iron liver content was nearly equal in both strains of rats. 5. 5. The results obtained would indicate that the lower susceptibility of the CHBBTHOM strain to acquire porphyria does not seem to be due to either: (1) congenital alterations of any parameters of the haem metabolic pathway, since the behaviour of normal animals from both strains was similar; or (2) a lower hepatic iron content in such animals. 6. 6. These findings would suggest that the differential response to HCB to this strain would be looked for in another metabolic pathway, such as that involved in the metabolization process of the toxic. © 1989.

Descripción: δ-aminolevulinic acid (ALA) is the precursor in the biosynthesis of porphyrins. The knowledge of both the regulation of ALA entrance and efflux from the cells and the control of porphyrin biosynthesis is essential to improve ALA-mediated photodynamic therapy. In this work, we studied the regulation of ALA uptake and efflux by endogenously accumulated ALA and/or porphyrins in murine mammary adenocarcinoma cells. Under our set of conditions, the haem synthesis inhibitor succinyl acetone completely prevented porphobilinogen and porphyrin synthesis from ALA, and led to an increase in the intracellular ALA pool. However, neither intracellular ALA nor porphyrin pools regulate ALA uptake or efflux during the first 15 min of the process. Based on temperature dependence data, ALA but not γ-aminobutyric acid (GABA) efflux is mediated by a diffusion mechanism. Moreover, the addition of extracellular GABA not only did not influence the rate of ALA efflux but on the contrary it affected ALA uptake, showing the contribution of a saturable mechanism for the uptake, but not for the efflux of ALA from the cells. © 2003 Cancer Research UK.

Descripción: The aim of this work was to test in vitro and in vivo the efficacy of the derivatives of 5-aminolevulinic acid (ALA): hexyl-ALA (He-ALA), undecanoyl-ALA and R,S-2-(hydroximethyl)tetrahydropyranyl-ALA (THP-ALA) as pro-photosensitising agents. The compounds were assayed in a cell line derived from a murine mammary tumour, in tumour explants and after injection of the cells into mice. In vitro, undecanoyl-ALA and THP-ALA did not improve ALA efficacy in terms of porphyrin synthesis. On the other hand, half of the amount of ALA is required to obtain the same plateau amount of photosensitiser from He-ALA. However, this plateau value cannot be surpassed in spite of the four-times higher accumulation of ALA/He-ALA from the ALA derivative. This shows that He-ALA conversion to porphyrins but not He-ALA entry to the cells is limiting. Employing ionic exchange chromatography, we found that 80% of total uptake was He-ALA whereas only 20% was ALA. This suggests that the esterases, probably themselves regulated by the heme pathway, are limiting the conversion of ALA derivatives into porphyrins. A similar situation occurs with THP-ALA. Tumour explant porphyrin results correlate well with cell line data. However, i.p. injection of ALA derivatives to mice resulted in a lower porphyrin concentration in the tumour when compared to the administration of equimolar amounts of ALA, indicating that there should be retention of ALA derivatives either within the blood vessels in the initial phase of distribution and/or within the capillaries of the tumour. © 2004 Cancer Research UK.

Descripción: 1. 1. Studies on porphyrin biosynthesis from exogenus ALA, at various time intervals as well as direct enzyme measurements (aminolevulimc acid dehydratase (ALA-D); porphobilinogenase (PBG ase) and deaminase were carried out in hemolysates of human erythrocytes from healthy controls and patients with lead poisoning (Pb), acute intermittent porphyria (AIP), porphyria cutanea tarda (PCT), erythropoietic protoporphyria (EPP), variegate porphyria (VP) and congenital erythropoietic porphyria (CEP). 2. 2. Inhibited ALA-D in Pb, reduced PBGase and deaminase in AIP, lower uroporphyrinogen decarboxylase in PCT, and diminished isomerase in CEP, were confirmed. In addition, ALA-D was found, reduced in AIP, unchanged in PCT and increased in EPP, VP and CEP. PBGase and deaminase were, on the other hand, increased in Pb and PCT, unchanged in VP and diminished in EPP and CEP. 3. 3. Total porphyrin biosynthesis is a function of time; compared to normals, is lower in CEP and AIP, but higher in PCT. 4. 4. The porphyrin profile changes along the time; uroporphyrin increases at longer intervals while that of coproporphyrin concomitantly diminished. A significance enhancement of octacarboxylic porphyrins was observed during the entire duration of the incubation in PCT hemolysates. In CEP the main porphyrin was always uroporphyrin I. 5. 5. Studies on both total porphyrins formed and their distribution were performed in hemolysates from cases of non-hereditary and hereditary PCT and AIP, before and after therapy. © 1980.

Descripción: The use of more lipophilic derivatives of 5-aminolevulinic acid (ALA) is expected to have better diffusing properties, and after conversion into the parent ALA, to reach a higher protoporphyrin IX (PPIX) formation rate, thus improving the efficacy of topical photodynamic therapy (PDT). Here we have analysed the behaviour of 3 ALA derivatives (ALA methyl-ester, hexyl ester and a 2-sided derivative) regarding PPIX formation, efficiency in photosensitizing cells and mechanism of cellular death. The maximum amount of porphyrins synthesized from 0.6 mM ALA was 47 ± 8 ng/105 cells. The same amount was formed by a concentration 60-fold lower of hexyl-ALA and 2-fold higher of methyl-ALA. The 2-sided derivative failed to produce PPIX accumulation. Applying a 0.6 J cm-2 light dose, cell viability decreased to 50%. With the 1.5 J cm-2 light dose, less than 20% of the cells survive, and higher light doses produced nearly total cell killing. Comparing the PPIX production and the induced phototoxicity, the more the amount of porphyrins, the greater the cellular killing, and PPIX formed from either ALA or ALA-esters equally sensitize the cells to photoinactivation. ALA-PDT treated cells exhibited features of apoptosis, independently on the pro-photosensitizer employed. ALA-PDT can be improved with the use of ALA derivatives, reducing the amount of ALA necessary to induce efficient photosensitization. © 2001 Cancer Research Campaign.

Descripción: The high levels of δ-aminolevulinate synthetase (ALA-S) in Rhodopseudomonas palustris cells grown anaerobically in the light (Ph) decrease to those found in cells grown aerobically in the dark (A), when the former cultures were vigorously oxygenated; simultaneously bacteriochlorophyll (Bchl) synthesis abruptly halted leading to diminished steady-state specific Bchl content. When flushing oxygen was interrupted, enzymic activity increased, whether chloramphenicol was present or not in the medium; if the protein synthesis inhibitor was added when oxygenation started, ALA-S declined in the same fashion as in its absence, but thereafter reactivation of the enzyme was lower than before. Succinyl-CoA-synthetase and ALA-dehydratase activities were also measured under the conditions described, and no changes at all have been observed. The existence of different forms of ALA-S in R. palustris depending on growth conditions is postulated along with the formation of low molecular weight factors which can modulate ALA-S activity by binding to the enzyme; a widespread mechanism in the adaptation of micro-organisms to changes in environment. It is also proposed that this particular regulatory phenomenon, could be referred to as a switch off/on mechanism controlling ALA-S activity in R. palustris. © 1987.

Descripción: 1. 1. Uroporphyrinogen carboxy-lyase (EC 4.1.1.d), the enzyme catalysing the decaroxylation of uroporphyrinogen to coproporphyrinogen, has been isolated from normal chicken erythrocytes. The enzyme was purified 220-fold with a yield of 24% from haemolysate supernatant by DEAE-cellulose batch treatment, (NH4)2SO4 fractionation and chromatography on DEAE-cellulose. 2. 2. The purified material appears to be homogeneous in polyacrylamide gel disc electrophoresis. 3. 3. The enzyme was heat labile and inhibited by sodium salt; the activity was enhanced by EDTA, GSH and boiled rat-liver extract. 4. 4. The influence of these chemical and physical agents on the removal of the first and second carboxyl groups from uroporphyrinogen was compared; the second group was more susceptible to these agents. 5. 5. The possibility that one or several enzymes were involved in the stepwise decarboxylation of uroporphyrinogen is discussed. 6. 6. The general name of porphyrinogen carboxy-lyase for the enzyme system is proposed because of the different porphyrinogens it can decarboxylate. © 1970.

Descripción: 1. 1. The effect of several metals and reagents on the decarboxylation rate of uroporphyrinogen I by using a 16-fold purified preparation of Uroporphyrinogen Decarboxylase from Rhodopseudomonas palustris, was studied. 2. 2. 1 mM Hg2+ and Cu2+ were strong inhibitors, 1 mM Zn2+ and Fe2+ under certain conditions and 1 mM Fe3+ and Cr3+ also inactivated the enzyme, but Pb2+, Cd2+, and Al3+ did not. Metals inhibition was reversed by 1 mM GSH or CvSH. 3. 3. 0.1 mM DTNB and PCMB, 1 mM pyridoxal phosphate and 100 mM chloral hydrate, as well as 1 mM 2-methoxy-5-nitrotropone and 0.2 mM diethylpyrocarbonate inhibited Uroporphyrinogen Decarboxylase; while GSH, CySH, N-ethylmaleimide, sodium thioglycolate, 1,4-dithioerythritol, EDTA and O-phenantroline did not modify activity. 4. 4. Data obtained would indicate that one cysteine, one or two histidine residues and probably a lysine group are required for enzyme activity. © 1987.

Descripción: 1. 1.|Porphobilinogenase has been isolated and purified from cow liver and its components, porphobilinogen deaminase and uroporphyrinogen isomerase, have been separated from each other and purified. 2. 2.|The effect of NH4+ was studied. The deaminase exhibited classical Michaelis-Menten kinetics in the absence or presence of NH4+, which at high concentrations behaved as a noncompetitive inhibitor of the deaminase. As expected from Hill plots, n = 1 both in the absence or presence of NH4+. Instead, when activity of porpho bilinogenase is plotted versus porphobilinogen concentration, sigmoid curves are obtained; but the presence of NH4+ at different concentrations altered the kinetic parameters of this enzymic system, again showing normal kinetics. In addition, n values were found to be 2 for porphobilinogen per porphobilinogenase molecule and 1 in the presence of NH4+ which behaves as a competitive inhibitor of the isomerase. Results are discussed in relation to the allosteric theories of monod et al.1,2 and liver porphobilinogenase is proposed to be an allosteric protein. 3. 3.|The presence of an ultrafiltrable factor which stimulates uroporphyrinogen formation from porphobilinogen has been revealed. © 1969.

Descripción: 1. 1. The activity of Succinyl CoA Synthetase (Suc CoA-S), Cysthationase, Rhodanese, Aminolevulinate Synthetase (ALA-S) and Aminolevulinate Dehydratase (ALA-D) was studied in old (405-407 subcultures) and young (34-36 subcultures) soybean callus clones as a function of the days of growing. 2. 2. Suc CoA-S, ALA-S and ALA-D activities were much lower in old than in young callus, while the activity of Cysthationase and Rhodanese was higher in old callus. 3. 3. ALA-S reached its maximum activity when Rhodanese and Cysthationase their minimum, on the 11th day of growth. It is suggested that the cellular content of a possible thio-compound which would regulate ALA-S activity, is controlled through its degradation by Rhodanese. © 1980.