Novel bioassay based on acetylcholinesterase and lactate dehydrogenase activities to evaluate the toxicity of chemicals to soil isopods

This study developed a bioassay with the isopod Porcellio dilatatus based on the activity of the enzymes acetylcholinesterase (AChE) and lactate dehydrogenase (LDH). The in vivo effects of the insecticides parathion-ethyl and endosulfan-sulfate on AChE and LDH activities of P. dilatatus under laboratory conditions were investigated. The route of uptake of the pesticides was through the food (alder leaves). Isopods were exposed to a wide range of concentrations of parathion or endosulfan (0.1, 1, 10, 25, 50, 100, 250, and 500 microg/g of food) for 21 days. After this period, the activity of AChE and LDH was determined. Parathion induced significant depression of both AChE and LDH activities. Animals fed with endosulfan-contaminated food exhibited lower LDH activities than control animals, while AChE activity was similar in all treatments. The results of the present investigation suggest that the isopod. P. dilatatus is a suitable species for use in toxicity tests and indicate that the enzymes AChE and LDH could be used as effect criteria both in laboratory and in field studies with this species.     

Clonal karyotypic abnormalities in gynecomastia

Gynecomastia is a benign condition that frequently occurs in the male breast gland; however, the cytogenetic data on this entity are very limited. To our knowledge, three cases have been reported in the literature, and the only one with an abnormal karyotype had a concomitant breast carcinoma. In this study we report clonal chromosomal alterations in a gynecomastia sample without any signs of adjacent malignant tissue. The nonrandom abnormalities observed were a deletion of 12p, monosomies of chromosomes 9, 17, 19, and 20, and the presence of a marker chromosome. Most of these alterations have been previously described in the literature in other breast lesions, including benign and malignant (male and female) tumors, indicating their recurrence and nonrandomness in abnormal processes of the mammary gland.     

Facilitation by arachidonic acid of acetylcholine release from the rat hippocampus

We investigated the effect of arachidonic acid (AA) on the release of [3H]acetylcholine ([3H]ACh) from the rat hippocampus. AA (3-30 microM) increased the basal tritium outflow and the field-electrically evoked release of [3H]ACh from hippocampal slices in a concentration-dependent manner. AA (30 microM) produced a 69+/-7% facilitation of the evoked and a 36+/-3% facilitation of basal tritium outflow. The effect of AA (30 microM) on the evoked tritium release was prevented by bovine serum albumin (BSA, 1%), which quenches AA, and was unaffected by the cyclooxygenase inhibitor, indomethacin (100 microM), and the lipooxygenase inhibitor, nordihydroguaiaretic acid (50 microM). Phospholipase A2 (PLA2, 2 U/ml), an enzyme that releases AA from the sn-2 position of phospholipids, mimicked the facilitatory effect of AA on the evoked tritium release (86+/-14% facilitation), an effect prevented by BSA (1%). The PLA2 activator, melittin (1 microM), enhanced the evoked tritium release by 98+/-11%, an effect prevented by the PLA2 inhibitor, arachidonyl trifluromethylketone (AACOCF3, 20 microM), and by BSA (1%). AA (30 microM), but not arachidic acid (30 microM), also facilitated (72+/-9%) the veratridine (10 microM)-evoked [3H]ACh release from superfused hippocampal synaptosomes, whereas PLA2 (2 U/ml) and melittin (1 microM) caused a lower facilitation (46+/-1% and 38+/-5%, respectively). The present results show that both exogenously added and endogenously produced AA increase the evoked release of [3H]ACh from rat hippocampal nerve terminals. Since muscarinic activation triggers AA production and we now observed that AA enhances ACh release, it is proposed that AA may act as a facilitatory retrograde messenger in hippocampal cholinergic muscarinic transmission as it has been proposed to act in glutamatergic transmission.     

Tachykinin NK(3)receptor involvement in anxiety

This study investigates the effects of intracerebroventricular injection of selective agonists and antagonists of tachykinin NK(3)receptor on performance of mice in the elevated plus-maze test. Mice were treated with either vehicle or 1, 10, 100 or 500 pmol of neurokinin B or senktide ([succinil-Asp(6), MePhe(8)]substance P(6-11), a natural and synthetic selective NK(3)receptor agonists, respectively. Other mice received similar doses of [Trp(7)beta-Ala(8)]NKA(4-10)or SR 142801 ((S)-N-(1-(3-(1-benzoyl-3-(3, 4-dichlorophenyl)-piperidin-3-yl)propyl)-4-phenyl-piperidin- 4-yl)-N-m ethylacetamide) tachykinin NK(3)receptor selective peptide and non-peptide antagonists, respectively. Senktide significantly increased the frequency of entries and the time spent in the open arms, which is compatible with an anxiolytic action. Neurokinin B treatment did not alter the plus-maze parameters in a significant way. Conversely, the NK(3)peptide antagonist [Trp(7)beta-Ala(8)]NKA(4-10), but not SR142801 non-peptide antagonist, showed a reverse effect, i.e. an anxiogenic profile of action, reducing the frequency and the time spent in the open arms. Co-injection of either senktide plus [Trp(7)beta-Ala(8)]NKA((4-10)), or senktide plus SR 142801, blocked the effects promoted by senktide, indicating that centrally-administered NK(3)receptor agonists and antagonists can modulate experimental anxiety.     

Adenosine modulates synaptic plasticity in hippocampal slices from aged rats

Adenosine is known to modulate synaptic plasticity in the hippocampus of young animals through activation of adenosine A1 receptors. The objective of the present study is to investigate whether the modulatory role of adenosine on phenomena of synaptic plasticity is maintained or modified in the hippocampus of aged animals. We compared the effects of the selective adenosine A1 receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 50 nM), on paired-pulse facilitation (PPF), long-term depression (LTD), long-term potentiation (LTP) and depotentiation elicited in hippocampal slices taken from young adult (5-6 weeks) and old (2 years old) male Wistar rats. DPCPX attenuated PPF both in young (1.64 +/- 0.05 vs. 1.76 +/- 0.05%, n = 6) and in old rats (1.33 +/- 0.05 vs. 1.55 +/- 0.1%, n = 6). LTD was only observed in the presence of DPCPX in both young (21.3 +/- 0.6%, n = 4) and old rats (14.4 +/- 0.9%, n = 6). LTP induced by high-frequency stimulation (HFS) was not significantly different in young and old animals, in the presence or in the absence of DPCPX. A larger depotentiation was observed in the presence of DPCPX in young rats (27.6 +/- 4.4% vs. 16.8 +/- 4.7%, n = 7) as well as in old rats (41.3 +/- 5.1% vs. 16.1 +/- 2.7%, n = 6). LTP induced by theta-burst stimulation was observed only in the presence of DPCPX (53.9 +/- 4.9%, n = 5) in young rats, but could be obtained either in the control solution (81.8 +/- 17.9%, n = 7) or in the presence of DPCPX (98.5 +/- 24.2%, n = 7) in old rats. The modulatory role of endogenous adenosine on synaptic plasticity is generally maintained in aged animals. Drugs interfering with adenosine A1 receptor effects could then be used in old animals to modify synaptic plasticity with relevant behavioural consequences.     

Slow sharp waves.

Slow sharp waves (SSHW) are of longer duration (around 200 msec and longer) than typical sharp wave discharges (70 to 200 msec). This pattern is not merely of academic interest, as the electroclinical correlation showed that SSHW were found in 23 patients, mostly above age 50 years, with serious illnesses of various etiologies. Epileptic seizures occurred in a minority of the cases. The electrophysiological basis remains unclear and there is no answer to the question, "what causes the relatively long duration of these discharges?"     

Bilateral Pseudomonas corneal ulcer in a disposable contact lens wearer.

PURPOSE: To describe a case of bilateral corneal ulcers caused by Pseudomonas in a disposable soft contact lens wearer. This case study discusses the role of patient examination, contact lens care instruction, and adequate patient supervision in reducing the risk of serious potential complications. METHODS AND RESULTS: A 17 year old student who had been using disposable soft contact lenses on an extended wear basis for 6 months presented complaining of pain in the left eye. When he was examined, a corneal ulcer with surrounding infiltrate was observed in the superior middle periphery of the left eye. Samples were collected for culture, and treatment with fortified cefalotin and gentamicin was started. After 8 hours the patient returned, now complaining of pain in the right eye. Examination of the right eye revealed a diffused keratitis with a mucopurulent discharge. A culture was taken, and the same treatment was instituted. The laboratory tests revealed Pseudomonas in both eyes. The bilateral corneal ulcers responded to therapy after 1 week of treatment. CONCLUSIONS: We discuss the factors involved in the occurrence of infectious keratitis in contact lens wearers, and stress that even disposable contact lens wear can be associated with serious complications. This case also highlights extended wear as one of the main risk factors for complications in disposable soft contact lens wear.     

Kainate receptors coupled to G(i)/G(o) proteins in the rat hippocampus.

Kainate receptors are a subtype of ionotropic glutamate receptors, permeable to cations and thus expected to have an excitatory depolarizing action on neurons. However, kainate receptor activation inhibits gamma-aminobutyric acid release in the hippocampus through activation of protein kinase C in a pertussis toxin-dependent manner, suggesting a coupling of kainate receptors to G proteins. Thus, we directly investigated the G protein coupling of kainate receptors in the rat hippocampus by using a selective kainate receptor agonist, [(3)H](2S,4R)-4-methylglutamate ([(3)H]MGA). [(3)H]MGA bound to a single site to hippocampal membranes with a K(D) value of 32 nM and a B(max) value of 1024 fmol/mg protein. This binding likely represents kainate receptors because it was displaced by domoate (K(i) = 4 nM), kainate (K(i) = 11 nM), and 6-cyano-7-nitroquinoxaline-2,3-dione (K(i) = 1.4 microM), but not by alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (K(i) > 10 microM), (RS)-alpha-methyl-4-phosphonophenylglycine (K(i) > 10 microM), or (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (K(i) > 10 microM). Guanylylimidodiphosphate (30 microM), which uncouples all G protein-coupled receptors, shifted to the right the saturation curve of [(3)H]MGA (K(D) = 133 nM). This effect was mimicked by pretreatment of hippocampal membranes with modifiers of G(i)/G(o) proteins [30 microM N-ethylmaleimide (K(D) = 98 nM) or 25 microgram/ml pertussis toxin (K(D) = 95 nM)] but not by a modifier of G(s) proteins [50 microgram/ml cholera toxin (K(D) = 32 nM)]. Treatment of solubilized hippocampal membranes with pertussis toxin (25 microgram/ml) decreased [(3)H]MGA affinity (K(D) = 105-113 nM), which was recovered by reconstitution of these pretreated solubilized hippocampal membranes with G(i)/G(o) proteins (K(D) = 41-76 nM). These results indicate that hippocampal kainate receptors are coupled to G(i)/G(o) proteins.     

Reactions of 'bay-region' and non-'bay-region' diol-epoxides of benz(a)anthracene with DNA: evidence indicating that the major products are hydrocarbon-N2-guanine adducts

The rates of reaction and the products formed when two vicinaldiol-epoxides derived from benz(a)an-thracene, anti-BA-3, 4-dioI1, 2-oxide (t-3, r-4-dihydroxy-t-1, 2-oxy-l, 2, 3, 4-tetrahydrobenz(a)anthracene)^* and anti-BA-8, 9-diol 10, 11-oxide (r-8, t-9-dihydroxy-t-10,ll-oxy-8, 9, 10, ll-tetrahydro-benz(a)anthracene) reacted withDNA were studied in vitro and the results were compared withthose obtained in similar experiments using anti-BP-7, 8-diol9, 10-oxide (r-7, t-8-dihydroxy-t-9, 10-oxy-7, 8, 9, 10-tetrahydrobenzo(a)pyrene).The reactivities appeared to decrease in the order anti-BP-7,8-diol 9, 10-oxide > anti-BA-3, 4-diol 1, 2-oxide anti-BA-8,9-diol 10, 11-oxide. The diol-epoxides reacted to a similarextent with single- and with double-stranded DNA but reactionswith dGMP, at equivalent concentrations, were much slower thanwith DNA. With the diol-epoxides of benz(a)anthracene, two principaladducts were present in DNA hydrolysates and evidence was obtained,based on pK determinations before and after nitrous acid treatment,consistent with their being N²-guanine derivatives, analogousto the known DNA-reaction products of benzo(a)-pyrene 7, 8-diol9, 10-oxide.