Acetylcholinesterase of Mytilus galloprovincialis LmK. hemolymph: a suitable environmental biomarker.
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Acetylcholinesterase↗
Biomedical subjects
J Coimbra
Publications and source records attributed to J Coimbra.
Polycyclic aromatic hydrocarbons inhibit in vitro ovarian steroidogenesis in the flounder (Platichthys flesus L.).
The in vitro effect of polycyclic aromatic hydrocarbons (PAHs) on ovarian steroidogenesis of the flounder (Platichthys flesus L.) was determined. Fully vitellogenic ovary tissue was in vitro incubated in the presence of phenanthrene, benzo[a]pyrene or chrysene, using 17alpha-hydroxyprogesterone or androstenedione as precursors. Androstenedione (A), testosterone (T) and 17beta-estradiol (E(2)) synthesised in the presence of PAHs were assayed by radioimmunoassay and results compared with control incubations. In order to establish the effect of PAHs on the steroidogenic enzyme systems cytochrome P450 17,20-lyase (P450-17,20l), 17beta-hydroxysteroid dehydrogenase (17beta-HSD) and cytochrome P450 aromatase (P450-arom), results were also compared with the action of ketoconazole (KCZ) and aminoglutethimide (AMG), wich are, respectively, inhibitors of cytochrome P450 steroidogenic enzymes and of P450-arom. KCZ inhibited secretion of A and E(2) in 65% and T in 40%, as a consequence of inhibited P450-17,20l and P450-arom. AMG inhibited P450-arom, which resulted in decreased E(2) synthesis to approximately 50% of control incubations. All the three PAHs inhibited A secretion by approximately 50% and E(2) from 10 to 40%. Because steroid conjugation was also inhibited by phenanthrene, it could be concluded that PAH action was mediated by an inhibitory effect over P450-17,20l, 17beta-HSD and P450-arom. Except for 17beta-HSD, PAHs resembled KCZ, and P450-17,20l was the most sensitive to their inhibitory effect. In conclusion, PAHs strongly blocked the activity of P450-17,20l, a rate-limiting enzyme for conversion of C21 to C19 steroids, and showed, therefore, the potential to disrupt the reproductive cycle of fish living in polluted environments, due to impairment of steroid biosynthesis.
Journal Article↗
Plasma steroid levels in female flounder (Platichthys flesus) after chronic dietary exposure to single polycyclic aromatic hydrocarbons.
The chronic effects of polycyclic aromatic hydrocarbons (PAHs) on ovary development, total hepatic lipids and plasma sex- and corticosteroid levels in female flounder (Platichthys flesus) were examined. Sexually mature feral female flounder were exposed via the diet to phenanthrene (0.5, 2.5 or 12.5 nmol/g food) or chrysene (0.4 nmol/g food) for 12 weeks, during the previtellogenic phase of the annual reproductive cycle. PAH exposure did not directly affect germ cell development since no structural and/or developmental differences were observed between control and exposed fish. On the contrary, all treatments resulted in altered plasma steroid levels. The most pronounced effect was the significant decrease in plasma 17 beta-estradiol to 19 +/- 11%, 27 +/- 7%, 63 +/- 20% and 61 +/- 12% in relation to control fish, respectively, in flounders exposed to 12.5, 2.5 or 0.5 nmol phenanthrene/g food and 0.4 nmol chrysene/g food. Impaired ovarian growth was not observed, most likely because experiments were ended before the period of vitellogenesis, even though a non-significant general decline in total hepatic lipids could be observed. Moreover, all exposed flounders, except fish fed with the highest amount of phenanthrene, showed a negative correlation between plasma 17 beta-estradiol and 17 alpha-hydroxyprogesterone levels (r = -0.46). One possible explanation is that PAH action may be mediated by a specific inhibition of steroidogenic enzymes. These findings provide evidence that selected PAHs are antiestrogenic xenobiotics with the capability to impair female teleost reproductive function.
Adrenal Cortex Hormones↗
Trout farm effluents: characterization and impact on the receiving streams.
Effluents from three rainbow trout (Oncorhynchus mykiss) farms located in Northern Portugal were characterized and their impact on the receiving streams was evaluated. Mean fish productions in the studied fish farms were 15, 55 and 500 t of trout per year, respectively. The feeding water was abstracted from Fornelo, Inha and Coura Rivers, at flow rates ranging from 1.2 (15 t year(-1) fish farm) to 4.8 litre s(-1) per ton annual fish production (500 t year(-1) fish farm). As the water flows through the farms, net variations in the chemical characteristics were observed: a mean reduction in the dissolved oxygen (DO) concentration between 0.7 and 2.4 mg litre(-1); mean increases between 1.9 and 3.2 mg CaCO3 litre(-1) for total alkalinity, between 0.9 and 14 mg litre(-1) for BOD5, between 0.27 and 1.46 mg litre(-1) for ammonia nitrogen (NH4-N), between 0.060 and 0.579 mg litre(-1) for soluble phosphorus (PO4-P) and less than 16 mg litre(-1) for suspended solids; variations in the pH value and nitrate nitrogen concentration were not statistically significant (p<0.05). At the 500 t year(-1) fish farm it was also possible to detect net increases of total hardness (3.2 mg CaCO3 litre(-1)), electric conductivity (19 mS cm(-1)) and permanganate value (3.6 mgO2 litre(-1)). At the other farms net variations in these parameters were not significant. Net mass flow variations reported to the annual fish production are presented. The DO mass flow decreased, on average, between 255 and 549 g t(-1) of fish per day. The mean daily BOD5 increase ranged from 353 to 1510 g t(-1) of fish. The corresponding ranges for the other parameters were 105-157 g t(-1) for NH4-N, 24-62 g t(-1) for PO4-P, 348-1035 g CaCO3 t(-1) for total alkalinity and 224 x 10(6)-506 x 10(6) t(-1) for mesophilic bacteria. Daily net variations of suspended solids, total hardness, electric conductivity and permanganate value were below 1753 g t(-1), 342 g CaCO3 t(-1), 2081 mS cm t(-1) and 392 gO2 t(-1), respectively. Longitudinal concentration profiles for the most relevant parameters show the impact of the effluent discharges on the physico-chemical and bacteriological river water quality downstream from the trout farms. Analyzing the situations from a purely chemical point of view, the polluted stretches were 3, 5 and 12 km long downstream from the effluent discharges, respectively. The microbiological contamination extended over longer distances.
Journal Article↗
Multiple sclerosis and intrathecal IgA synthesis.
A clinically definite diagnosis of multiple sclerosis was done in a 61 year-old woman who displayed severe cerebellar and pyramidal tract involvement. Symptoms developed 5 years before with unsteadiness of gait and difficulties in walking. Diagnosis was supported by evoked potentials studies and magnetic resonance imaging. However, the cerebrospinal fluid (CSF) analysis was very unusual. CSF albumin and IgG concentrations were normal, as well as the IgG index. In contrast, the IgA level and the IgA index were markedly increased and the local synthesis of IgA was estimated at 31.36 mg/l. Reduction by dithiotreitol did not change the IgA level. On affinity immunoblots, oligoclonal IgA bands were not detected but oligoclonal IgG bands were present. The strong local production of IgA in this patient seems to be therefore polyclonal.
Dithioerythritol↗
[Neuropathy in Waldenstrom's macroglobulinemia].
The association of a neuropathy and a paraproteinaemia such as Waldenström's macroglobulinaemia is frequent and not fortuitous. This paper reports a slowly progressive, predominantly sensory neuropathy, occurring in a 69-year-old man, as the first sign of a Waldenström's macroglobulinaemia. A saphenous [correction of sural] nerve biopsy revealed a mixed process of primary demyelination and axonal degeneration. Accumulations of immunoglobulin M were observed in the myelin sheets and the perineurium by immunocytochemistry. Infiltrations of inflammatory blood cells and accumulations of amyloid material were absent in the peripheral nerve. The axonal loss was most prominent in central areas of the nerve fascicles. This find supports the hypothesis of an ischemic mechanism for the axonal degeneration plus secondary demyelination, associated to a direct immunological attack against myelin. The various types of peripheral nerve involvement in Waldenström's macroglobulinaemia, as well as the admitted mechanisms of nerve lesion and the therapeutic approaches to this still unclear neuropathy are briefly reviewed.
Aged↗
[ERCP/ES in the therapy of acute calculous pancreatitis].
In the medical press there are several data confirming the value of E.R.C.P. and E.E.S., in the therapeutical approach of acute lithiasic pancreatitis (A.L.P.). Nowadays it is a first line endoscopic technic on the therapeutical approach in A.L.P. permitting to clean out the biliary tree of stones, eliminating the etiological factor of the disease. It's the experience of the group of E.R.C.P./E.S.E. of Hospital dos Capuchos that we will present on this paper.
Acute Disease↗
[Prefrontal syndrome as a manifestation of intracranial dural arterio-venous malformation].
The authors present a clinical case of an intracranial dural arteriovenous malformation with clinical manifestations of a prefrontal syndrome, documented with its respective diagnostic tests, including imaging studies. A number of considerations are being enlarged upon, concerning possible pathophysiological mechanisms.
Arteriovenous Fistula↗
Ecdysteroids in the shrimp Palaemon serratus: relations with molt cycle.
Ecdysteroids were studied during the molt cycle of the shrimp Palaemon serratus using radioimmunoassay and HPLC. Continuous presence of ecdysteroids was observed in whole extracts, with two hormonal peaks: a minor peak during stage B and a major one during stage D2. The ecdysteroid titers were generally higher in females than in males. The ecdysteroid peak at stage B was more pronounced in the integument (cuticle and epidermis) than in other tissues and, at this time, 20-hydroxyecdysone was the predominant form. The observed 20-hydroxyecdysone peaks in stages B and D2 are correlatable to the previously reported rise in integumental carbonic anhydrase activity.
Animals↗
[Familial peripheral neuropathy caused by susceptibility to entrapment (tomaculous neuropathy)].
The authors describe a case of hereditary neuropathy with liability to pressure palsies (entrapment), and compare it to reports from literature. The main characteristics are: autosomal dominant inheritance, recurrent mononeuropathies (ulnar, median, peroneal, brachial plexus), and specific features at nerve biopsy. The sensory nerve reveals predominantly demyelinating alterations, having the remaining myelin fibres focal thickenings, the so called tomaculous, and shows numerous subperineural structures named Renaut Bodies. The EMG findings show a slowing of the nerve conduction velocities and an increase of distal latencies.
Adult↗