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At least 523 records · Page 29Linked to original sources
PubMed1973

Decreased liver activity of porphyrin-metal chelatase in hepatic porphyria caused by 3,5-diethoxycarbonyl-1,4-dihydrocollidine. Studies in rats and mice.

1. A difference has been found between rats and mice in their sensitivity to the porphyrogenic effect of drugs. Mice are more sensitive than rats to 3,5-diethoxycarbonyl-1,4-dihydrocollidine, but less sensitive than rats to 2-allyl-2-isopropylacetamide. 2. Use has been made of this difference in sensitivity to ascertain the importance of the decrease of liver porphyrin-metal chelatase activity in porphyria caused by 3,5-diethoxycarbonyl-1,4-dihydrocollidine. Mice, which are more sensitive than rats to the stimulation of 5-aminolaevulinate caused by this drug, are also more sensitive with respect to the decrease of chelatase activity. 3. In both species, after treatment with 3,5-diethoxycarbonyl-1,4-dihydrocollidine, the ratio between chelatase activity and 5-aminolaevulinate activity is linear with respect to the reciprocal of the liver porphyrin concentration. This suggests that under these conditions the degree of porphyrin accumulation depends on the balance between rate of porphyrin formation and rate of porphyrin utilization. 4. Compound SKF 525-A (2-diethylaminoethyl 3,3-diphenylpropylacetate) when given before 3,5-diethoxycarbonyl-1,4-dihydrocollidine prevents the appearance of porphyria in the rat and also largely prevents the decrease of chelatase activity. In the mouse it is much less effective in preventing porphyria and it is almost completely inactive in protecting the chelatase from a decrease in activity. 5. Cycloheximide, when given before 3,5-diethoxycarbonyl-1,4-dihydrocollidine also inhibits the induction of 5-aminolaevulinate synthetase and the appearance of porphyria in the rat, but does not prevent the decrease of chelatase activity. These results suggest that two successive stages can be distinguished in the induction process: a first stage leading to inhibition of haem synthesis and a second stage requiring synthesis of protein in the liver and leading to stimulation of 5-aminolaevulinate synthetase.

5-Aminolevulinate Synthetase↗
PubMed1973

The effects of chemical porphyrogens and drugs on the activity of rat liver tryptophan pyrrolase.

1. Drugs such as phenobarbitone and phenylbutazone, which increase the concentration of microsomal haem and cytochrome P-450, also increase the saturation of rat liver apo-(tryptophan pyrrolase) with its haem activator, as does the haem precursor 5-aminolaevulinate. 2. At 4h after the administration of the porphyrogens 2-allyl-2-isopropylacetamide, 3,5-diethoxycarbonyl-1,4-dihydrocollidine and griseofulvin, the total pyrrolase activity is increased whereas the haem saturation of the apoenzyme is decreased. This decreased saturation is prevented by pretreatment of the animals with the inhibitor of drug-metabolizing enzymes, SKF 525-A. 3. Pretreatment of rats with the above porphyrogens inhibits the rise in holo-(tryptophan pyrrolase) activity produced by subsequent administration of cortisol, tryptophan and 5-aminolaevulinate with two single exceptions, the possible reasons for which are discussed. 4. At 24h after the administration, in starved rats, of a single daily injection of the above porphyrogens for 1 or 2 days, the holoenzyme activity is significantly increased. 5. It is suggested that the saturation of rat liver apo-(tryptophan pyrrolase) with its haem activator can be modified by treatment known to cause destruction, inhibition of synthesis, increased utilization and enhanced synthesis of liver haem. The possible involvement of the latter phenomenon in the aetiology of mental disorders in some patients with porphyria is discussed.

Acetamides↗
PubMed1986

Photoreduction of protochlorophyllide and its relationship to delta-aminolaevulinic acid synthesis in the leaves of dark-grown barley (Hordeum vulgare) seedlings.

The photoreduction of protochlorophyllide (Pchl) in dark-grown leaves of barley (Hordeum vulgare) brings about the synthesis of delta-aminolaevulinic acid (AmLev). Manipulation of the Pchl level in the leaves by incubation in AmLev indicated that the production of AmLev was intimately related to the state of the Pchl reductase ternary complex. Free Pchl reductase that is unassociated with substrate/product appeared at first to be essential for the photoinduction of AmLev synthesis. Experiments on the photoreduction of Pchl in dark-grown leaves exposed to low-energy red-light, however, showed that photoreduction and AmLev synthesis would occur when the Pchl reductase, together with substrate, was maintained at relatively high endogenous concentration. Under such conditions the availability of free reductase protein would be negligible. An alternative scheme is presented, therefore, that can explain many, if not all, of the observations on AMLev synthesis and its close relationship to Pchl reduction, and which is based on a common supply of NADPH for the reduction of glutamate to AmLev and the synthesis of chorophyll(-ide).

Aminolevulinic Acid↗
PubMed1987

Isolation and characterization of an aminolevulinate-requiring Rhodobacter capsulatus mutant.

Using transposon Tn5 mutagenesis, we isolated a mutant strain of Rhodobacter capsulatus that requires aminolevulinate for growth. Southern blot analysis indicated that this strain has a single Tn5 insertion. The addition of 0.1 mM aminolevulinate to the medium allowed the mutant to grow either aerobically or photosynthetically with generation times similar to those of the parental strain. When grown photosynthetically, bacteriochlorophyll accumulation increased with increasing aminolevulinate concentration. The mutant strain had only 10% of the normal aminolevulinate synthase activity, but it had a normal level of porphobilinogen synthase activity. The requirement for aminolevulinate could be satisfied by porphobilinogen, hemin, or protoporphyrin. While the mutant grew well on agar plates containing any of these substrates, growth in liquid media containing hemin or protoporphyrin was poor. Introduction of an R' factor containing all the known R. capsulatus bch genes into the mutant strain did not relieve the requirement for aminolevulinate, suggesting that the Tn5 insertion is not within the bch region.

Aminolevulinic Acid↗
PubMed1965

URINARY AMINO-ACETONE EXCRETION IN LEAD WORKERS.

Urinary amino-acetone concentrations were determined in a group of 51 persons with industrial exposure to lead and the findings compared with those obtained from a control group of 27 persons having no exposure to lead.A good correlation was found between delta-aminolaevulinic acid and amino-acetone excretion in the control group but this correlation was not so well defined in the lead-exposed group. In this group excretion of amino-acetone seemed to be better correlated with excretion of delta-aminolaevulinic acid for values less than 0.6 mg.% than with values greater than 0.6 mg.%. All the men concerned in the investigation were employed in dusty occupations. Hypotheses are put forward to attempt to explain the differences in excretion of amino-acetone noted amongst lead workers with high excretion of delta aminolaevulinic acid.Little correlation was found between amino-acetone excretion and that of either porphobilinogen or coproporphyrin.

Acetone↗
PubMed1980

Effects of urinary volume on urinary concentrations of lead, delta-aminolaevulinic acid, coproporphyrin, creatinine, and total solutes.

Urinary volume was related to urinary concentrations of lead, delta-aminolaevulinic acid (ALA), coproporphyrin (COPRO), creatinine, and total solutes in nine lead workers. On a log scale, linear relationships were found between urinary volume and the urinary concentrations. There was a certain difference in the extent of the effects of urinary volume on the urinary concentrations. For example, the concentration of creatinine was more affected by urinary volume than those of lead, ALA, and total solutes among the substances examined: similarly, the concentration of COPRO more than that of ALA. An equation was introduced to eliminate the effects of urinary volume on urinary concentrations. The effects of urinary volume on the concentrations adjusted to urinary specific gravity, osmolality, and creatinine are discussed in the light of these findings.

Adult↗
PubMed1976

[Determination of delta aminolevulinic acid in urine in a population exposed to lead].

Uninary levels of delta-aminolevulinic acid (ALA) were determined in 93 workers exposed to lead. Control groups were made up of 32 employees of the same factories of test group and of 24 patients with no history of lead exposure. In the first group, urinary concentration of ALA was 28.55 mg/1; it was 3.36 mg/1 in the second group and 2.98 mg/1 in the other control group. Differences between workers and controls were statistically significant.

Aminolevulinic Acid↗
PubMed1975

[Aminolcevulinic acid excretion in women before and after delivery and in their newborn infants (authors transl)].

A report is given on the excretion of variation of-aminolaevulinic acid (ALA) as an index of the lead load in pregnant women at term and at one and also at four weeks after delivery in both mothers and the newborn infants. The mean values in women were 7.2 + 3.7 before delivery 9.0 + 4.1 one week and 4.1mg ALA/1 urine four weeks after delivery; mean values of 5.2 + 3.2 one week after birth and 2.2 + 1.0 mg ALA/1 urine four weeks after birth were recorded in the newborn infants, according to the method of Davis and Andelman. Two groups were set up: mothers coming from the rural environs of Vienna and mothers living in the centre of the city. The ALA excretion was 14% lower in the former group (20% four weeks post partum) as compared with the mothers living in the city. When these data are considered against a threshold value of 10 ALA/1 urine (set up by the "Hauptverband der Berufsgenossenschafen", Bonn, West Germany, using the same method) the mean value of 9.0mg ALA/1 urine (with individual values of up to 17.4mg ALA/1 urine) in mothers one week after delivery already seems extremely serious.

Adult↗
PubMed1990

Phototoxic damage to sebaceous glands and hair follicles of mice after systemic administration of 5-aminolevulinic acid correlates with localized protoporphyrin IX fluorescence.

The skin of albino mice given 5-aminolevulinic acid (ALA) by intraperitoneal injection rapidly developed the characteristic red fluorescence of protoporphyrin IX. Fluorescence microscopy of frozen tissue sections revealed intense red fluorescence within the sebaceous glands and a much weaker fluorescence within the epidermis and hair follicles. Little or no fluorescence was detected in the dermis, blood vessels, or cartilage of the ear. Light microscopy of skin taken at intervals after whole-body exposure of ALA-injected mice to photoactivating light revealed destruction of sebaceous cells, focal epidermal necrosis with a transient acute inflammation, and diffuse reactive changes in the keratinocytes. The dermis showed transient secondary edema and inflammation. The location and severity of the phototoxic damage correlated well with the location and intensity of the red fluorescence. The light-exposed skin appeared to recover completely except for a persistent reduction in the number of hair follicles.

Aminolevulinic Acid↗
PubMed1985

[Interrelation of delta-aminolevulinic acid and brain myelin proteins as affected by benzene and lead].

An experimental model of subacute lead and benzene intoxication was induced in rabbits. It increased significantly delta-aminolevulinic acid (14C-ALA) incorporation into CNS myelin. ALA stably fixes on myelin proteins, especially Wolfgram proteins. In spite of this about one half of ALA incorporated into myelin linked with its basic proteins. Lead and benzene intoxication cause changes in the proportion of the basic fractions of myelin proteins. The amount of basic proteins increases, while the amount of proteolipid and Wolfgram proteins decreases. Lead and especially benzene intoxication decreases exogenous ALA insertion into basic proteins and proteolipid proteins, with ALA fixation on Wolfgram proteins remaining unchanged.

Aminolevulinic Acid↗
PubMed1987

Enzymatic conversion of glutamate to delta-aminolevulinic acid in soluble extracts of Euglena gracilis.

Glutamate was converted to the chlorophyll and heme precursor delta-aminolevulinic acid in soluble extracts of Euglena gracilis. delta-Aminolevulinic acid-forming activity depended on the presence of native enzyme, glutamate, ATP, Mg2+, NADPH or NADH, and RNA. The requirement for reduced pyridine nucleotide was observed only if, prior to incubation, the enzyme extract was filtered through activated carbon to remove firmly bound reductant. Dithiothreitol was also required for activity after carbon treatment. delta-Aminolevulinic acid formation was stimulated by RNA from various plant tissues and algal cells, including greening barley leaves and members of the algal groups Chlorophyta (Chlorella vulgaris, Chlamydomonas reinhardtii), Rhodophyta (Cyanidium caldarium), Cyanophyta (Anacystis nidulans, Synechocystis sp. PCC 6803), and Prochlorophyta (Prochlorothrix hollandica), but not by RNA derived from Escherichia coli, yeast, wheat germ, bovine liver, and Methanobacterium thermoautotrophicum. E. coli glutamate-specific tRNA was inhibitory. Several of the RNAs that did not stimulate delta-aminolevulinic acid formation nevertheless became acylated when incubated with glutamate in the presence of Euglena enzyme extract. RNA extracted from nongreen dark-grown wild-type Euglena cells was about half as stimulatory as that from chlorophyllous light-grown cells, and RNA from aplastidic mutant cells stimulated only slightly. delta-Aminolevulinic acid-forming enzyme activity was present in extracts of light-grown wild-type cells, but undetectable in extracts of aplastidic mutant and dark-grown wild-type cells. Gabaculine inhibited delta-aminolevulinic acid formation at submicromolar concentration. Heme inhibited 50% at 25 microM, but protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllide inhibited only slightly at this concentration.

Adenosine Triphosphate↗
PubMed1986

Sorbent therapy of the porphyrias. V. Adsorption of the porphyrin precursors delta-aminolevulinic acid and porphobilinogen by sorbents in vitro.

The acute attacks of the acute hepatic porphyrias may be precipitated by the excessive intracellular accumulation of the porphyrin precursors delta-aminolevulinic acid (ALA) or porphobilinogen (PBG). Sorbents that bind porphyrin precursors in the gastrointestinal tract may interrupt their enterohepatic circulation, thus reducing the body burden of these materials and minimizing the frequency or severity of acute attacks. We have determined the adsorption capacities (Qm's) of several activated charcoals and the ion exchange resin cholestyramine for ALA and PBG. Qm's (mg ALA or PBG adsorbed/gm dry sorbent) were determined from Langmuir isotherms, which were derived from studies of the amount of porphyrin precursor adsorbed after the addition of a constant amount of ALA or PBG to varying amounts of sorbent. These experiments were carried out pH 8.2 in 0.1% desoxycholate, to simulate conditions of the small intestine. Extremely high Qm's were obtained for all charcoals and both porphyrin precursors; those for cholestyramine were one or several orders of magnitude lower. For ALA, the Qm of Gulf Bio-Systems Super Char charcoal (110 +/- 35 [SD]) was not significantly greater than that of Med-Corp Acta-Char charcoal (95 +/- 20), but it did exceed those of all other charcoals by a statistically significant amount. For PBG, the Qm of Super Char (68 +/- 14) was marginally greater than that of Mallinckrodt USP charcoal (42 +/- 21, t8 = 2.18, p approximately equal to 0.06), but it was significantly greater than that of Acta-Char charcoal (27 +/- 12). All sorbents adsorbed ALA or PBG at comparable rates, and the complex of sorbent and porphyrin precursor appeared to be undissociable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗