Which component of treatment is important for changes of cortical epileptic afterdischarges after status epilepticus in immature rats?

Role of lithium chloride and paraldehyde in acute changes after lithium-pilocarpine status epilepticus (SE) induced at postnatal day 12 was studied in 15-day-old rats. In addition to SE group four other groups were formed: naïve animals without any injection, lithium chloride group, paraldehyde group and lithium-paraldehyde group. Cortical epileptic afterdischarges (CxADs) induced by increasing intensities of stimulation current were used as a measure of excitability. SE animals did not exhibit any change in duration of CxADs with increasing stimulation intensity in contrast to naïve control with a progressive prolongation of CxAD. LiCl group was similar to SE rats whereas paraldehyde and lithium-paraldehyde groups exhibited some progress in duration of ADs. Lithium chloride participates in short-term changes of CxADs after SE. Paraldehyde and combination of lithium and paraldehyde are similar to naïve controls.

DNA-protein cross-link formation in Burkitt lymphoma cells cultured with benzaldehyde and the sedative paraldehyde.

Exposure to aldehydes represents potential risks to human and animal health. Cyclic aldehydes such as benzaldehyde, 2-furaldehyde, and paraldehyde were found to induce formation of stable DNA-protein cross-links (DPXs) in cultured human lymphoma cells. A relationship between increased cytotoxicity and DPX formation was observed with each aldehyde. Paraldehyde is a sedative drug used predominately in treatment of ethanol withdrawal. Paraldehyde was the most potent cross-linking aldehyde studied, yet least cytotoxic. Although DPX formation by aliphatic aldehydes is well-known, this study confirms the potential for cyclic aldehydes to cause formation of DPXs in cultured cells at therapeutically relevant doses.

Outcome of status epilepticus in immature rats varies according to the paraldehyde treatment.

PURPOSE: To test effects of paraldehyde on behavioral outcome of status epilepticus (SE) in developing rats. METHODS: Motor SE was induced by LiCl-pilocarpine in rats on postnatal (P) day 12 or 25. Two hours after SE onset, animals were injected with a single dose of paraldehyde (0.07 and 0.3 ml/kg in the P12 group and 0.3 and 0.6 ml/kg in the P25 group). Effects on seizure severity and mortality were evaluated. Growth of animals and their motor abilities were monitored until the adulthood. Three months after SE, cognitive abilities were tested by using the Morris water maze. RESULTS: Both tested doses of paraldehyde equally affected motor seizures. Convulsions continued until the paraldehyde administration, but then they quickly subsided in all groups. During the subsequent 24 h, occasional clonic seizures occurred in P25 animals treated with the lower dose of paraldehyde. Only hyperactivity and/or automatisms were observed in the other experimental groups. Mortality was not affected by the dosage of paraldehyde. The higher dosage of paraldehyde improved recovery after SE in both age groups. No difference was found in motor abilities between controls and SE animals, except shortening of time spent on the rod in the rotarod test in the P12 group. In P25 rats, treatment with a higher dosage of paraldehyde improved learning abilities compared with the lower dosage. In the P12 group, animals treated with the lower dosage exhibited slightly impaired learning compared with controls and animals receiving the higher dosage. CONCLUSIONS: Paraldehyde injected 2 h after SE onset modulates long-term outcome in immature rats in a dose-related manner.

Brain-derived neurotrophic factor superinduction parallels anti-epileptic--neuroprotective treatment in the pilocarpine epilepsy model.

Antiepileptic drugs provide neuroprotection in several animal models of brain damage, including those induced by status epilepticus (SE). The mechanisms involved in this action are unknown, but neurotrophic factors such as brain-derived neurotrophic factor (BDNF) may play a role. In this study we investigated the changes in BDNF levels in rats in which SE had been induced by pilocarpine injection (400 mg/kg i.p.) and continued for several hours (unprotected group). In other animals (protected groups), SE was suppressed after 30 min by intraperitoneal injection of either diazepam (10 mg/kg) + pentobarbital (30 mg/kg) or paraldehyde (0.3 mg/kg). In diazepam + pentobarbital-treated rats the hippocampal damage caused by SE was significantly lower (p < 0.05) than in unprotected animals. In addition, 2 and 24 h after pilocarpine injection, the levels of BDNF mRNA were moderately increased in the unprotected group, but 'superinduced' in protected animals, especially in the neocortex and hippocampus. A time-dependent increase in BDNF immunoreactivity was also found by western blot analysis in rats treated with diazepam + pentobarbital. In contrast, a decrease of BDNF immunoreactivity occurred in the unprotected group. In conclusion, these results show that neuroprotection induced by anti-epileptic drugs in pilocarpine-treated rats is accompanied by strong potentiation of BDNF synthesis in brain regions involved in SE.

Characterization of Ehrlichia risticii binding, internalization, and proliferation in host cells by flow cytometry.

The binding, internalization, and proliferation of Ehrlichia risticii in P388D1 cells and equine polymorphonuclear (PMN) leukocytes were studied by immunofluorescent staining and flow cytometric analysis. The binding of ehrlichiae to P388D1 cells at 4 degrees C was dose dependent, and the antigens of bound organisms were susceptible to pronase treatment. Additionally, the binding of ehrlichiae to P388D1 cells was diminished when either P388D1 cells or ehrlichiae were treated with 1% paraformaldehyde for 30 min or 0.25% trypsin for 15 min. These results indicate that the ehrlichial ligand and host cell receptor are likely surface proteins. Following incubation at 37 degrees C, bound E. risticii and/or its antigens were removed with pronase and indirect immunofluorescent staining in the presence of saponin was used to examine intracellular ehrlichiae. Our results indicate that E. risticii was internalized into P388D1 cells within 3 h and proliferated by 48 h of incubation. The microfilament-disrupting agent cytochalasin D and the transglutaminase inhibitor monodansylcadaverine were used to differentiate between phagocytosis (sensitive to cytochalasin) and receptor-mediated endocytosis (sensitive to monodansylcadaverine) of E. risticii by P388D1 cells. In concentrations that produced distinctive morphological changes and inhibited phagocytosis of polystyrene latex beads, cytochalasin D did not suppress the infectivity of E. risticii. Binding, internalization, or proliferation of E. risticii was not affected by cytochalasin D. However, monodansylcadaverine inhibited infection of E. risticii in a dose-dependent manner. The agent did not affect the attachment of ehrlichiae to host cells, but it did suppress internalization and proliferation. These results suggest that E. risticii is internalized by receptor-mediated endocytosis and that productive infection by E. risticii does not depend on phagocytosis by the P388D1 cells. Although E. risticii did not bind to the surface of equine PMN leukocytes at 4 degrees C, organisms were taken up by this cell at 37 degrees C. E. risticii, however, failed to survive in equine PMN leukocytes.

Classical genetic analyses of responses to sedative-hypnotic drugs in crosses derived from long-sleep and short-sleep mice.

A classical (Mendelian) genetic analysis of responses to eight sedative-hypnotic compounds (ethanol, urethane, trifluoroethanol, chloral hydrate, barbital, paraldehyde, methyprylon, pentobarbital) was conducted in crosses derived from mouse lines that were selectively bred for differential duration of anesthesia following ethanol. The sleep-time responses of these mice, the long-sleep (LS) and short-sleep (SS) mouse lines, as well as the F1, F2 and backcross (F1 x LS, F1 x SS) generations were measured. Generally, differences in responses among the generations were greater for water soluble compounds than were differences for more lipid soluble compounds. Also, the inheritance of responses to water soluble compounds could be explained primarily by additive effects of alleles while the inheritance patterns for more lipid soluble compounds were more complex. Genetic correlation with ethanol response decreased with increasing lipophilicity. These results suggest that the selection of the LS-SS mouse lines was specific for water soluble anesthetic agents. Because several of these agents are known to act at GABA receptors, examination of the interactions of compounds which differ in lipid solubility at GABA receptors from LS and SS mice may prove useful in elucidating the mechanism of the anesthetic actions of ethanol and other drugs.

Effects of paraldehyde on the convulsions induced by administration of soman in rats.

The ability of paraldehyde, a potent central nervous system depressant, to prevent the convulsions induced by the organophosphate soman, an irreversible inhibitor of acetylcholinesterase, was studied in rats. Paraldehyde (0.1-500 mg/kg, im) administered 10 min before soman (100 micrograms/kg, sc) did not protect against seizures. Co-administered with atropine sulfate (10 mg/kg, im), paraldehyde produced a clear dose-dependent anticonvulsant response. Although this pre-treatment could delay the occurrence of death, it did not produce any change in the soman-induced 24 h mortality rate. Thus, co-administration of paraldehyde and atropine sulfate might constitute a valuable tool to be used against the convulsant consequences of soman poisoning. However, supplementary pre-medication, in addition to paraldehyde and atropine sulfate, remains necessary to improve the antilethal capacity of the pre-treatment.

Role of acetaldehyde in ethanol-induced increase in the activity of phosphatidate phosphatase in rat liver.

The effect of ethanol on the activity of phosphatidate phosphatase was studied in rat liver using membrane-bound phosphatidate and phosphatidate emulsion as substrate. A single large dose of ethanol (5 g/kg body wt) caused an increase in the enzyme activity measured with membrane-bound phosphatidate after an approximate 2-hr lag period in both cytosolic and microsomal fraction and the increase was approximately 2.2- and 1.8-fold that in control rats at 5 hr in cytosol and microsomes, respectively. A similar time-course of the increase was obtained with phosphatidate emulsion as substrate. These ethanol-induced increases in the activity of cytosolic and microsomal phosphatidate phosphatase were blocked by the pretreatment of rats with actinomycin D. The ethanol-induced rise in the activity of cytosolic and microsomal phosphatidate phosphatase measured with membrane-bound phosphatidate was abolished when rats were injected with pyrazole prior to ethanol administration. On the other hand, pretreatment with cyanamide enhanced the increase in cytosolic activity produced by a suboptimal dose of ethanol (1 g/kg), while microsomal activity was not affected by the same treatment, suggesting that acetaldehyde may be selectively involved in the ethanol-induced increase in the activity of cytosolic phosphatidate phosphatase. This hypothesis was supported by a finding that administration of paraldehyde, a cyclic trimer of acetaldehyde, produced an increase (35%) in cytosolic activity, but not in microsomal activity.

The action of intravenous anaesthetic and central depressant drugs on the contractures elicited by tetraethylammonium in the chick biventer cervicis muscle.

A group of intravenous anaesthetic drugs was compared with methohexitone sodium for their ability to potentiate tetraethylammonium induced contractures of the chick biventer cervicis muscle (TEA test). The equipotent concentrations in the TEA test were: methohexitone 8.8 X 10(-5) M, propanidid 1.78 X 10(-4) M, althesin 3.58 X 10(-5) M (in terms of alphaxalone), etomidate 1.6 X 10(-4) M, thiopentone 2.13 X 10(-5) M and valium 4.95 X 10(-5) M. There was no relation between activity in the TEA test and excitatory muscular activity reported clinically. The central depressant drugs ethyl alcohol and urethane also potentiated TEA but they were only active in high concentrations (10(-1) - 10(-2) M). alpha-Chloralose was inactive but paraldehyde (3.8 X 10(-3) M) actually reduced TEA induced contractures. Lipophilicity is only one factor in determining activity in the TEA test, the ability to block Ca2+ reuptake may also be important.

Aldehyde-induced platelet aggregation.

Formaldehyde, acetaldehyde, malondialdehyde, glutaraldehyde and paraldehyde, when added in vitro to platelet-rich plasma, generate a similar distinct platelet aggregation response which is dose dependent when measured with a manual visual microscopic technique and by computerized image analysis, 'computerized platelet aggregation analysis'. Light transmission aggregometry did not measure this aggregation in a reliable manner. The aggregating reaction was specific to the aldehyde group and was not seen when the aldehyde was replaced by an alcohol, ketone, or acetate group in the case of acetaldehyde. The maximal aggregating effect of these aldehydes was directly proportional to the number of aldehyde groups per molecule. Aggregation was found to require the presence of plasma, but not von Willebrand's factor.

The role of paraldehyde in the rapid preparation of aldehyde fuchsin.

Preparation of aldehyde fuchsin normally requires ripening for 3 to 5 days. By using a 5-fold excess of paraldehyde a fully potent aldehyde fuchsin can be prepared in 24 hr at room temperature. Aldehyde fuchsin prepared by both normal and accelerated ripening afforded comparable results, including selective staining of unoxidized pancreatic B cells. Dried aldehyde fuchsin prepared form pararosaniline and reconstituted in acid alcohol has spectrophotometric properties different form the ripened strain. Reconstituted aldehyde fuchsin stains unoxidized B cells adequately only if staining time is extended. Excess paraldehyde added to reconstituted aldehyde fuchsin retards decomposition but does not produce a normal stain by spectrophotometric standards. Warming of aldehyde fuchsin solutions to accelerate ripening has been shown to produce deleterious effects and should be avoided.

Uropharmacology: X. Central nervous system stimulants and depressants.

Several drugs that are utilized primarily for their effects on the central nervous system also affect lower urinary tract function. Most of these effects are produced by the action of these drugs on adrenergic and cholinergic receptors or by direct action of lower urinary tract musculature. Central nervous system stimulants and depressants which are known to affect the storage or evacuation role of the lower urinary tract are discussed.

Abnormality in body curvature of Cyprinus carpio after injection of anaesthetics.

Abnormalities in the body curvatures were noticed in Cyprinus carpio after the injection of anaesthetics, viz. paraldehyde, tertiary butyl alcohol and butanol. These abnormalities occurred behind the dorsal fin and progressively developed over a period of four months. The abnormalities affect the locomotion and speed of swimming of the fish and appear to be due to toxic effects of the anaesthetics.

Activating and anesthetic effects of general depressants.

The long-sleep (LS) and short-sleep (SS) lines of mice were derived by selective breeding with respect to ethanol sleep time. We found that in current generations LS mice also have longer sleep times than SS mice to trichloroethanol and paraldehyde. Two subsequent experiments tested our hypothesis that mice that are relatively insensitive to the hypnotic effects of depressant drugs might be relatively activated by low doses of these drugs. Both experiments failed to support the hypothesis. First, although SS mice were more activated than LS mice by subhypnotic doses of paraldehyde, the lines did not differ in the degree of activation produced by low doses of trichloroethanol. Second, among mice from a genetically heterogeneous population (HS), there was no relation between the degree of activation induced by a low dose of ethanol and sensitivity to the hypnotic effects of a higher dose.

The effects of certain anaesthetic and anti-convulsant drugs on the CSF potassium fluxes of the dog.

1 A technique has been developed for open-ended perfusion of the cerebroventricular system of the unanaesthetized dog.2 Perfusion with an artificial CSF solution containing inulin and (42)K allowed the potassium fluxes out of and into the CSF to be monitored over a period of 2 to 3 hours.3 Sodium thiopentone and sodium pentobarbitone, in doses producing light anaesthesia, caused varying degrees of depression (up to 50%) in the CSF potassium fluxes, influx being consistently more affected than efflux. These effects are attributed to a decrease in the potassium exchange between extracellular and intracellular compartments in the brain.4 Diazepam depressed both potassium fluxes by up to 10% while there was some evidence that diphenylhydantoin depressed only potassium influx.5 Paraldehyde, in contrast to the other drugs, when given at a dose level sufficient to produce light anaesthesia, stimulated CSF potassium fluxes, particularly efflux.