Monopyrroles in porphyria,psychosis and lead exposure

• 1.1. It has been shown that the monopyrrole other than porphobilinogen excreted in excess in acute porphyria is 3-ethyl-5-hydroxy-4,5-dimethyl-Δ³-pyrrolin-2-one (hydroxyhaemopyrrole lactam). A gas liquid chromatographic method has been developed for measurement of the concentrations of this compound. Hydroxyhaemopyrrole lactam was measured in the urine of patients with porphyria, psychiatric in-patients and subjects with industrial lead exposure. Concentrations were found to be raised in porphyria, but no correlation could be found between the concentrations of this compound and current clinical condition. In psychiatric patients, there was again significant elevation of hydroxyhaemopyrrole lactam, although no such rise could be found in lead workers. The studies in the lead workers and porphyria patients would suggest that there is an association between the concentrations of hydroxyhae-mopyrrole lactam in urine and porphobilinogen excretion.
• 2.2. The effects of the monopyrroles; hydroxyhaemopyrrole lactam; haemopyrrole; hydroxykryptopyr-role lactam; kryptopyrrole phyllopyrrole and ethyl-3-acetyl-2,4-dimethyl-pyrrole-5-carboxylate (EADC), have been examined on porphyrin metabolism in the rat. All significantly raised urinary porphyrin excretion and hepatic porphyrin concentrations. Hydroxyhaemopyrrole lactam caused an increase in the excretion of porphyrins associated with an increase in the activity of the rate-limiting enzyme of haem biosynthesis, δ-aminolaevulinic acid synthase. These results suggest some association between such pyrrole production and the biochemical changes found in acute porphyria.

     

Biochemistry of porphyria

• 1.1. The porphyrias are a group of metabolic disorders arising from defects in the haem biosynthetic pathway. Most forms are inherited as Mendelian autosomal dominants, but some types are recessive and others acquired through exposure to porphyrinogenic drugs and chemicals. There is a linked group of diseases, which are not porphyrias, but have in common alterations of haem biosynthesis.
• 2.2. The processes of haem biosynthesis are now well understood and the molecular biology of the functions and dysfunctions in the porphyrias are currently an area of intensive investigation.
• 3.3. The acute porphyrias. Acute Intermittent Porphyria, Variegate Porphyria and Hereditary Coproporphyria are of most importance since attacks of these may be life-threatening.
• 4.4. These diseases that usually present with a neurovisceral attack are characterized by excess production of the porphyrin precursors, 5-aminolaevulinate and porphobilinogen because of lowered activity of Porphobilinogen deaminase.
• 5.5. A variety of factors may precipitate these attacks including various drugs, alcohol, smoking, dieting or fasting and variations in steroid hormone levels.
• 6.6. The non-acute porphyrias are largely dermatological conditions, which present clinically as cutaneous photosensitivity. The dermatological changes are caused by the photosensitizing properties of circulating porphyrins and are accompanied by systemic effects of these porphyrins.

     

Kinetics of porphyrin accumulation in cultured epithelial cells exposed to ALA

• 1.1. The kinetics of porphyrin accumulation in cultured mammalian epithelial cells (CNCM-I-221) during exposure to ALA was investigated.
• 2.2. The total porphyrin synthesized is a function of ALA concentration and the incubation time. The cellular porphyrin content exhibited a saturation pattern, reaching a plateau at about 0.04 fmol porphyrins/cell. A biphasic time-dependent increase in the total porphyrin synthesized was observed.
• 3.3. After 3 hr of exposure to ALA the rate of synthesis increased to ahnost twice the initial rate, reaching between 0.02 and 0.05 fmol porphyrins/cell/hr depending on serum concentration in the medium.
• 4.4. Two effects of FBS on ALA-stimulated porphyrin accumulation were observed. Greater total porphyrin synthesis was found when incubations were made in 10% FBS compared to those in 1% FBS.
• 5.5. The higher serum concentration also caused a greater release into the medium of the porphyrins generated in the cells with a calculated half-life of 24 min in 10% serum-supplemented medium compared with 62 min in 1% serum.
• 6.6. The results obtained from cell synchronization experiments suggest that there is little obvious cell cycle-dependent variation in the synthesis of porphyrins from ALA.
• 7.7. The small differences in the intracellular porphyrin content that were observed may be attributed to a slight reduction in the rate of loss of porphyrins in G2/M cells.

     

The peculiarities of nitrogen excretion in sturgeons (Acipenser ruthenus) (Pisces,Acipenseridae)—I. the influence of ration size

• 1.1. The nonfaecal nitrogenous excretion rate in starved sterlet fingerlings and fingerlings fed on different rations was investigated. The weight of the fish and temperature of the water was 43 g and 17.5°C, respectively.
• 2.2. In the nonfaecal excrements of starved sterlets the ammonia: urea ratio was substantially lower than in teleosts. This ratio was found to be 1.4:1.
• 3.3. In fed sterlets the urea excretion rate was higher than in starved ones but independent of ration size.
• 4.4. During the day the urea excretion rate in sterlets was constant.
• 5.5. The ammonia excretion rate accelerated 2 hr after feeding and reached its peak duration 6–11 hr after depending on the ration size.
• 6.6. Total ammonia output in the sterlet increased following the increase of ration size up to 8.4% of body wt. Further increases in ration size did not cause the corresponding elevation of ammonia excretion rate.

     

Experience with the red cell uroporphyrinogen synthase (URO-S) assay in kindreds with acute intermittent porphyria (AIP)

• 1.1. Erythrocyte URO-S activity was assessed in members of 14 AIP kindreds and correlated with clinical symptoms and urinary excretion of porphobilinogen (PBG).
• 2.2. When a single URO-S assay showed levels in an indeterminate range, in most cases genotype ascertainment was achieved by repeat assay, assay by more than one laboratory, PBG quantitation in the urine, and analysis of pedigrees. In about 5% of cases, this approach still precluded definition of the genotype.
• 3.3. Neither symptoms of AIP nor urinary excretion of PBG correlated with red cell URO-S activity.

     

Development of chronic hepatic porphyria (porphyria cutanea tarda) with inherited uroporphyrinogen decarboxylase deficiency under exposure to dioxin

• 1.1. Exposure to dioxin triggered a clinically manifest chronic hepatic porphyria (porphyria cutanea tarda) in two patients (brother and sister) with hereditary uroporphyrinogen decarboxylase deficiency.
• 2.2. The patients showed a decrease of erythrocyte uroporphyrinogen decarboxylase activity to ~ 50% of controls even in reinvestigations after three years, whereas clinical symptoms and porphyrinuria had improved considerably. Only a subclinical phase of chronic hepatic porphyria persisted. Subnormal uroporphyrinogen decarboxylase activity could be determined in altogether nine family members.
• 3.3. The remission of porphyria cutanea tarda into a subclinical phase occurred after chloroquine therapy. Subclinical phases of chronic hepatic porphyria (type A) in other family members remitted without special therapy.
• 4.4. Among the 60 persons dioxin-exposed by the Seveso accident, a secondary coproporphyrinuria was found in 22% of examined patients with transition to a subclinical chronic hepatic porphyria in 5 cases. The changes had subsided completely after one year. A persistence of the transition state in 3 cases is probably due to alcohol influence. None of these cases developed a porphyria cutanea tarda.
• 5.5. The investigations showed that a hereditary disposition is necessary for biochemical and clinical expression of chronic hepatic porphyria after a unique dioxin exposure. This is not given in the sporadic cases: after a unique dioxin exposure they indeed develop a symptomatic disturbance of porphyrin metabolism but not a clinically relevant chronic hepatic porphyria.
• 6.6. We conclude that a unique acute exposure to dioxin can trigger the chronic hepatic porphyria disease process in persons with an underlying genetic abnormality of uroporphyrinogen decarboxylase.

     

Structural requirements in dihydropyridines for ferrochelatase inhibition and δ-aminolevulinic acid synthetase induction

• 1.1. A series of analogues of 3,5-diethoxycarbonyl-1,4-dihydro-2,4,6-trimethylpyridine (DDC) was investigated for hepatic δ-aminolevulinic acid (ALA)-synthetase inducing and ferrochelatase-inhibiting activity in the 17-day-old chick embryo.
• 2.2. A DDC analogue was found which was capable of inducing ALA-synthetase activity without inhibiting ferrochelatase activity.
• 3.3. On the other hand we were unable to find a DDC analogue with the ability to inhibit ferrochelatase activity which was devoid of ALA-synthetase-inducing activity.

     

Chemistry of porphyrin biosynthesis: Results and applications

• 1.1. Pairs of suitable mono-, di-, and tripyrroles, differently labeled with ¹⁴C and ³H, were submitted to in vivo incorporation into heme in competition experiments. It turned out that the di- and tripyrroles, in striking contrast to porphobilinogen and uroporphyrinogen III compete little with the intermediates bound to the enzyme. Some inspecifity of the enzyme system is indicated by similarity of the low but significant incorporation of different di- and tripyrroles.
• 2.2. Systematic investigation of the in vitro condensation of porphobilinogen derivatives under conditions of kinetic control revealed that the ratio of uroporphyrinogen I in the reaction mixture dropped steadily in favour of the III/IV isomers with increasing acidity. A mechanistic explanation is given, by which the formation of the biologically essential uroporphyrinogen III appears less cryptic than assumed before.
• 3.3. Derivatives of nor- and homoporphobilinogen with equal side chains, provided by convenient syntheses, gave porphyrins by biomimetic condensation in high yields. Among these porphyrins are useful model compounds, as well as novel nonplanar porphyrins and porphyrinogens with remarkable properties.

     

The influence of chloroquine on the formation of porphyrins by yeasts

A single two-compartment model suitable for studying the production and elimination of porphyrins from cells was prepared. Chloroquine with increasing concentrations:-

• 1.1. Inhibits the total production of porphyrins.
• 2.2. Reduces intracellular concentration of porphyrins.
• 3.3. Increases transversal permeation of porphyrins through the cellular membrane.

     

Trehalose synthase and trehalase behaviour in yeast cells in anhydrobiosis and hydrobiosis

• 1.I. Trehalose synthase and trehalase behaviour has been analysed in cultured yeast cells isolated from baker's yeast to increase the understanding of the mechanisms involved in trehalose content modifications observed in anyhydrobiois and hydrobiosis.
• 2.2. After desiccating yeast cells to a constant weight, trehalose levels sharply increased, whereas the glycogen content decreased, trehalose synthase was stimulated and trehalase was significantly inhibited.
• 3.3. In desiccated cells after a rehydration for 15 min, trehalose levels dropped, the glycogen content further decreased, the activity of trehalose synthase declined while that of trehalase was dramatically stimulated.
• 4.4. After rehydration for 12hr, while the trehalose and glycogen content decreased even more, the behaviour of the two enzymes was completely reversed, trehalose synthase being activated and trehalase inhibited.
• 5.5. The reasons for such impressive enzyme activity alterations in desiccated and rehydrated cells for the moment remain unknown.

     

Comparison of the porphyrin patterns in patients with porphyria cutanea tarda in Czechoslovakia and Denmark

• 1.1. The incidence of porphyria cutanea tarda (PCT) has increased considerably in Denmark during the last decade (Table 1) but is much higher in Czechoslovakia than in Denmark.
• 2.2. We therefore made a detailed study of the urinary porphyrin excretion pattern in 10 cases of PCT from Copenhagen and 10 from Prague.
• 3.3. The results are presented (Table 2). They show no simple pattern.
• 4.4. Comparison with the type subdivision of Doss et al. (Table 3) and the important findings of Piñol Aguade et al. show that such elaborate type division, involving considerable and time-consuming analytical work, belong to research and have limited value in clinical work.

     

Sulphate conjugation is the main route of pentachlorophenol metabolism in Daphnia magna

• 1.1. Daphnia magna were exposed for 24 hr to ¹⁴C-labelled pentachlorophenol (PCP) at an initial concentration of 20μg/l in the incubation water. Occurrence of free PCP and its metabolites were measured both from the animals and the water.
• 2.2. Hydrophilic metabolites excreted into water were analysed, after acid or enzymatic hydrolyses, with a liquid-liquid extraction and TLC.
• 3.3. PCP was metabolized and excreted, perhaps solely, via the sulphate conjugation. The average excretion rate, 2.65nmol/g/hr, accounted for 35% of the absorption rate measured at the start of exposure.
• 4.4. Neonate daphnids had an equal ability to metabolize PCP as the older animals. Bioconcentration in young animals was, however, only 23% of that in adult ones.
• 5.5. Effect of naturally humic water on metabolization and excretion of PCP was negligible.

     

The effect of time on physiological changes in eel Anguilla anguilla,induced by lindane

• 1.1. Eel were exposed to a sublethal concentration of lindane (0.335 ppm) for 6, 12, 24, 48, 72 and 96 hr.
• 2.2. Concentrations of glycogen, glucose, lactate, pyruvate and lipids were determined in gill tissue after lindane exposure.
• 3.3. Gill glycogen descreased and glucose levels increased at 6 hr of treatment, lactate and pyruvate concentration increased between 6 and 48 hr. Total lipid values decreased between 6 and 24 hr; thereafter, the levels increased up to 72 hr of exposure.
• 4.4. Clear changes were found in all parameters tested in gill tissues. The observed effects of lindane on metabolism in fish are discussed in relation to acute stress syndrome.

     

Correlation of water translocation,cuticle dehydration and post-ecdysial sclerotization by the american cockroach

• 1.1. Haemolymph volume decreases during the initial 16 hr post-ecdysial period, increases after water ingestion and subsequently drops until the inter-ecdysial level is reached.
• 2.2. Total body water follows a similar pattern, but the changes are not as pronounced.
• 3.3. Tissue water is inversely proportional to the total body water.
• 4.4. Soluble cuticle protein declines throughout the initial 16 hr period while both β-glucosidase and alkaline phosphatase activity is lost within 6 hr after ecdysis.
• 5.5. Dehydration of the cuticle also occurs during the immediate 6 hr post-ecdysial period.
• 6.6. These data suggest that the formation of the protein-insoluble matrix is linked with water loss.
• 7.7. Water removal may decrease the distance between molecules allowing specific reactions to take place.

     

δ-Aminolevulinic acid transport in Saccharomyces cerevisiae

• 1.1. This work represents the first approach to characterize the transport system of haem pathway precursors, such as δ-aminolevulinic acid (ALA), in two strains of Saccharomyces cerevisiae, a wild type, D27, and a HEM R⁺ mutant.
• 2.2. ALA transport occurs unidirectionally by a sole active system with an apparent K_M of 0.10 mM, at the optimum pH of 5.0. ALA uptake is influenced by both the carbon and nitrogen source; this suggests a rather complex regulation mechanism.
• 3.3. This transport is not mediated by the general amino acid permease (GAP).
• 4.4. ALA uptake is strongly inhibited by compounds harboring a methyl-amine terminus suggesting that this group is essential for ALA transport; however, the electric environment of the carboxylic group may be also important for the interaction between ALA and its transporter active site.
• 5.5. We have found differences in ALA transport which would indicate a different regulation mechanism for this system in both strain cells.

     

Acute stress suppresses plasma estradiol levels in female alligators (Alligator mississippiensis)

• 1.1. Five adult, female alligators (Alligator mississippiensis) were captured at night during the breeding season, and a blood sample taken within 5 min of capture.
• 2.2. The alligators were physically restrained (tied to boards) and additional blood samples taken at 4, 8, 12, 16, 22, 28, 38, and 48 hr after capture. After the last blood sample was collected the animals were released.
• 3.3. Plasma estradiol-17β and corticosterone were measured by radioimmunoassay. Estradiol declined significantly from initial values by 22 hr post capture, but remained unchanged for 48 hr.
• 4.4. Plasma corticosterone rose from a mean of 0.8 ng/ml at capture to 12.6 ng/ml after 4 hr. Corticosterone continued to rise up to 16 hr then declined after 22 hr. From 28 until 48 hr corticosterone again increased significantly.
• 5.5. These results demonstrate that acute stress in female alligators causes significant suppression of plasma estradiol and a biphasic pattern of corticosterone secretion.

     

The effect of feed restriction on certain haematological indices,enzymes and metabolites in Nubian goats

• 1.1. Some effects of restricting feed intake for 96 or 168 hr were determined in male Nubian goats.
• 2.2. Goats restricted for 96 hr lost 11.6% of their body weight, and goats restricted for 168 hr lost 19.8%.
• 3.3. Feed restriction for up to 168 hr did not produce significant effects on the heart rate, respiratory rate or rectal temperature.
• 4.4. Haemoglobin concentration, packed cell volume and erythrocyte number were all decreased by feed restriction. There was also a tendency towards eosinopenia and lymphopenia.
• 5.5. Feed restriction for 96 or 168 hr raised the plasma activity of aspartate transaminase, and did not affect significantly cholinesterase activity. Plasma amine oxidase activity was significantly reduced in goats restricted for 168 hr.
• 6.6. Feed restriction produced significant increases in the blood or plasma concentrations of lactate. pyruvate, non-esterified fatty acids, cholesterol, ketone bodies and bilirubin.
• 7.7. Significant decreases were found in the concentrations of total protein and calcium.
• 8.8. No significant changes were observed in the plasma concentrations of glucose, sodium or potassium.

     

Acid hydrolase activity in tissues of mice after physical stress

• 1.1. The activities of β-glucuronidase and cathepsin D and the protein concentration were assayed from brain, kidney, liver, cardiac muscle and skeletal muscle (m. rectus femoris) samples from mice (Mus musculus) 1, 3, and 6 days after intermittent exhaustive (duration 100–145min) and submaximal prolonged (duration 9 hr) running on treadmill.
• 2.2. The activity of β-glucuronidase in skeletal muscle strongly increased being the highest 3 days after both exertions. Cathepsin D activity also slightly increased. In cardiac muscle β-glucuronidase activity was unaffected. Cathepsin D activity slightly increased 3 days after intermittent exhaustive exercise.
• 3.3. The specific activities of β-glucuronidase and cathepsin D in the liver increased 1 day after the both exertions. Simultaneously the protein concentration decreased. In the kidney β-glucuronidase activity and protein concentration were unaffected but cathepsin D activity decreased 1 day after intermittent exhaustive exercise.
• 4.4. In the brain protein concentration transiently decreased 3 days after the exertions. β-Glucuronidase activity transiently decreased 1 day after intermittent exercise thereafter increasing 6 days afterwards above the control level. Cathepsin D activity decreased 1 day after intermittent exercise but was unaffected after prolonged submaximal exercise.
• 5.5. Physical stress affected to varying extent the acid hydrolase activities in all organs studied.

     

Acute toxicity and bioaccumulation of endosulfan in rotifer (Brachionus calyciflorus)

• 1.1. The acute toxicity of endosulfan was determined for the freshwater rotifer Brachionus calyciflorus.
• 2.2. The mean 24 hr lc₅₀ value for endosulfan was 5.15 ppm with a coefficient of variation of 14.7%.
• 3.3. Rotifers were exposed at two sublethal concentrations (1.5–2.0 ppm) of endosulfan for bioaccumulation experiments, for an exposure time of 24, 48, 72 and 96 hr. The rotifers were fed with Nannochloris oculata (5 × 10⁵cell/ml).
• 4.4. The highest accumulation of endosulfan was found 24 hr after the start of the exposure to 1.5 ppm of the toxicant. A steady-state concentration in rotifer was reached between 24–48 hr, followed by a gradual decrease until 96 hr.

     

Human urinary excretion of l-histidine-related compounds after ingestion of several meats and fish muscle

• 1.1. After oral administration of the muscle of skipjack tuna, about 90% of ingested anserine (Ans) was excreted quickly into urine as Ans (8%) and π-methylHis (82%), indicating the fast decomposition of Ans into π-methylHis. This was also the case for chicken muscle ingestion.
• 2.2. After eel muscle ingestion, carnosine (Car) excretion was only 1 % of the ingested whereas almost no increase was found in His, a constituent of Car, indicating the re-utilization of this essential amino acid. Similar results were also obtained from beef and pork ingestion.
• 3.3. In all cases, the urinary excretion of these compounds reached a maximum within 7 hr after ingestion and returned to the level of meat-free diet within 40 hr.