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A continuous fluorescence displacement assay for phospholipase A2 using albumin and medium chain phospholipid substrates.

A continuous fluorescence assay for phospholipase A2 is described which involves the displacement of the highly fluorescent fatty-acid probe 11-(dansylamino) undecanoic acid from albumin by decanoic acid released as a result of phospholipase A2-catalyzed hydrolysis of didecanoyl-phosphatidylcholine. Using the phospholipase A2 from Naja naja, this assay will detect activity from 1 ng of pure enzyme and a linear response in terms of fluorescence change with time is observed up to about 50 ng of enzyme. The assay is compared with the original fluorescence displacement assay (Wilton, D.C., 1990, Biochem. J. 266, 435-439) which uses rat liver fatty acid binding protein instead of albumin and is able to utilize any natural long chain phospholipid as substrate. The present assay will provide a very convenient method for detection during enzyme purification of the low molecular weight secreted phospholipase A2 and other phospholipases A that can hydrolyze medium chain phospholipids. The assay should also allow the identification of inhibitors of these enzymes. Other substrates including dioleoylphosphatidylcholine and 1-stearoyl-2-arachidonoylphosphatidylcholine were also evaluated in the assay.

Animals↗

Cardiovascular toxicities of nandrolone and cocaine in spontaneously hypertensive rats.

The outcome of concurrent abuse of cocaine and anabolic steroids is largely unknown and merits investigation. The present study was designed to determine whether an animal model could be developed for investigation of the toxic responses to simultaneous administration of cocaine and an anabolic steroid, nandrolone decanoate. Twenty-four male spontaneously hypertensive rats (SHR), all 7 weeks of age, were assigned randomly to four groups: (1) control, (2) cocaine, (3) nandrolone, and (4) cocaine plus nandrolone. Metabolic measurements and indirect (tail-cuff) blood pressure and heart rate measurements were performed on all rats every 2 weeks. All drug treatment groups exhibited significantly (p < 0.05) higher levels of blood pressure after 6 weeks of treatment when compared to the control group. Cocaine plus nandrolone group exhibited the lowest heart rate compared to other groups. Rats were euthanized at 13 weeks of age, and different tissues were removed, blotted dry, and weighed. The kidney, levator ani muscle, and seminal vesicle (with prostate glands) weights in both nandrolone-receiving groups were higher than those of the control and cocaine groups. Testicular weights of the cocaine plus nandrolone group were less than those of the control and cocaine groups. Hearts were fixed in 10% buffered formaldehyde before myocardial dimension measurements were performed. The nandrolone group showed increased vertical ventricular diameters when compared to the control and cocaine groups. The nandrolone group also displayed higher vertical ventricular circumferences when compared to all the other groups. Finally, the cocaine plus nandrolone group had the greatest ventricular weights (per 100 g body weight) and left ventricular volumes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Effect of dosing vehicle on the dermal absorption of fluazifop-butyl and fomesafen in rats in vivo.

One important factor which may influence the extent and rate of percutaneous absorption is the dosing vehicle. The purpose of the experiments described was to compare the effect of dosing vehicles of different polarities on the absorption of two herbicides across rat skin in vivo. Rats were dosed dermally with either fluazifop-butyl (logP(oct) 4.5) or fomesafen sodium salt (logP(oct) -1.2) in propylene glycol (PG), octanol (OCT), or ethyl decanoate (ED), and the amount of radioactivity excreted in urine was determined. Absorption rates were estimated from the urinary excretion data and from blood kinetic data derived from intravenously dosed rats. For fluazifop-butyl the average rate of absorption (x10(-2) micrograms/hr-1 +/- SE) was not greatly influenced by the dosing vehicle (OCT, 2.94 +/- 0.08; ED, 3.66 +/- 0.10; PG, 3.95 +/- 0.32) despite relatively large differences in solubility (PG, 38 mg/ml; OCT, and ED, > 600 mg/ml). These results were consistent with the finding that there was at most only a twofold difference in the epidermal membrane:vehicle partition coefficients (km). In contrast, the absorption rate of fomesafen from PG (1.98 +/- 0.04) was approximately half that of ED (3.98 +/- 0.06) and OCT (4.49 +/- 0.08) for the first 30 hr after application and was in keeping with solubility data (PG, 638 mg/ml; OCT, 12 mg/ml; ED, < 10 mg/ml). At later time points the absorption of fomesafen from PG increased; this is discussed in relation to the penetration-enhancing properties of PG.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗

Anabolic-androgenic steroid effects on the sexual behavior of intact male rats.

Six separate experiments were conducted which examined the effects of long-term administration of anabolic-androgenic steroid (AAS) compounds on the sexual behavior of gonadally intact male rats. The six AAS compounds analyzed in this study were 17alpha-methyltestosterone, methandrostenolone, nandrolone decanoate, stanozolol, oxymetholone, and testosterone cypionate. In each experiment, subjects received daily injections of a high, medium, or low dose of the AAS compound, or the oil vehicle, for 12 weeks. Sexual behavior was quantified weekly. Twelve weeks of administration of the high dose of three AAS compounds, 17alpha-methyltestosterone, stanozolol, and oxymetholone, eliminated male sexual behavior. These treatments also suppressed serum testosterone levels. The remaining compounds had minimal effects on sexual behavior at any dose. Thus, in intact male rats the six AAS compounds examined in these studies evoked a range of behavioral and endocrine responses that varied as a function of the specific compound and dose administered.

Androgens↗

Inhibition of estrogen-induced sexual receptivity by androgens: role of the androgen receptor.

Both naturally occurring and synthetic androgens have been shown to inhibit estrogen-induced sexual receptivity when administered to ovariectomized (OVX) rats. The mechanisms by which androgens exert these effects, however, remain unclear. Experiments were conducted to determine the role of the androgen receptor in the inhibition of estrogen-induced sexual receptivity in OVX rats by using flutamide, an androgen receptor antagonist. In each experiment, OVX Long-Evans rats received 6 consecutive days of estradiol benzoate (EB; 2.0 microg/day) followed by 15 days of EB concurrent with flutamide (10. 0 mg/kg; twice daily) or the vehicle and one of the following androgens or the vehicle: dihydrotestosterone propionate (7.5 mg/kg), 3alpha-androstanediol (3.75 mg/kg), 17alpha-methyltestosterone (7.5 mg/kg), stanozolol (7.5 mg/kg), or nandrolone decanoate (7.5 mg/kg). On Day 15, all female rats received progesterone (P; 1.0 mg/rat) 4 h before testing. Tests for sexual receptivity were conducted on Days 3, 6, 14, and 15 of androgen/flutamide treatment. Each androgen inhibited sexual receptivity as expected, and concurrent treatment with flutamide reversed the inhibitory effects of all androgens on sexual receptivity on all test days. High levels of sexual receptivity were displayed in response to P on Day 15, regardless of experimental treatment. These results suggest that naturally occurring and synthetic androgens act at the androgen receptor to inhibit estrogen-induced sexual receptivity in OVX rats.

Androgen Antagonists↗

Measurement of the Surface Elasticity of an Adsorbed Monolayer by Continuous Surface Deformation

The elasticity of a monolayer adsorbed from a surfactant solution is considered by continuous surface deformation. For all kinds surface deformations a single relation between the elasticity and the effective time should be obtained (master curve). This effective time depends on the rate of deformation and on the kind of deformation. The relation between elasticity and effective time was proven experimentally for a decanoic acid solution at a concentration 10(-7) mol cm-3. The following surface deformations are considered: (i) expansion at a constant dilatation rate, (ii) compression at a constant dilatation rate, (iii) linear expansion, (iv) linear compression, and (v, vi) compression and expansion in a some what more complicated way. From these data the Gibbs elasticity and the diffusion relaxation time are obtained. These parameters are also obtained by longitudinal wave method of Lucassen-Van den Tempel. Both set of parameters are comparable. Finally the situation at a growing drop with constant flow rate is considered (Triton X-100) to show that also here the approach is followed.

Journal Article↗

Hydrophobic Laminin-Related Peptides: Synthesis and Surface Properties.

The synthesis of hydrophobic peptide derivatives related to the laminin sequence [YIGSR(NH(2))] is described. Hydrophobicity is achieved by the attachment of decanoic, myristic, or stearic acids to the amino terminal end of the peptide. Moreover, a cholesterol residue was also introduced as succinimidoyl-cholesteryl moiety at the same position. These peptidic compounds are designed to be inserted into lipid bilayers to prepare, what can be considered as, immunoliposomes to target these vesicles to tumor cells. Physicochemical aspects related to their surface activity, insertion into lipid layers, spreadibility, formation of aggregates, and haemolytic activity have been studied as a previous step in the selection of the most convenient derivative. The results obtained indicate that these peptide derivatives show a high tendency to form aggregates in aqueous media, this fact reducing their interaction with lipid mono- and bilayers. The most suitable derivatives for interacting with liposomes are myristoyl and decanoyl. Copyright 2001 Academic Press.

Journal Article↗

Reactions of oxaprozin-1-O-acyl glucuronide in solutions of human plasma and albumin.

Hydrolysis and rearrangement (isomerization by acyl migration) of oxaprozin glucuronide are greatly accelerated by plasma and human serum albumin. Albumin accounts for all the hydrolytic activity in plasma and no esterase is involved. The isomeric esters formed by rearrangement are also good substrates for the hydrolysis reaction. Another reaction between oxaprozin glucuronide and albumin leads to covalent binding of the aglycone. Similar reactions leading to covalent binding have been described for other acyl glucuronides by several investigators. In the case of oxaprozin, there is little or no potential for biological significance of covalent binding because the reaction is almost entirely inhibited by low concentrations of the drug. All three reactions are pH dependent but not to the same extent. They can be considered to be transacylations to the hydroxyl ion (hydrolysis), to a different OH-group of the glucuronic acid moiety (rearrangement) or to a nucleophilic group on the albumin molecule (covalent binding). All three reactions are greatly inhibited by the same compounds suggesting a common reaction site. This site has certain features in common with the indole or benzodiazepine binding site of human serum albumin. A scheme is proposed in which the first step is reversible binding of the acyl glucuronide to this site in analogy to the known reversible binding of reactive esters (such as p-nitrophenyl acetate) to the same site. All three reactions are inhibited by compounds such as naproxen and decanoic acid which are known to also inhibit the acylation of albumin by reactive esters and the reversible binding of benzodiazepines.

Carbon Radioisotopes↗

Diminished D2 dopamine receptor function and the emergence of repetitive jaw movements.

Oral movements in rats, repetitive jaw movements (RJM), can be induced in a dose dependent manner by a specific D1 agonist, SKF 38393, and decreased by D2 receptor stimulation with a specific D2 agonist, LY 141865. Irreversible D1 receptor inactivation by N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline severely reduced oral responses induced by SKF 38393, whereas such blockade of D2 receptors greatly augmented the D1 mediated behavior. Further, we found that chronic prolonged D2 receptor blockade following administration of fluphenazine decanoate facilitated repetitive jaw movements.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

Induction of tardive dyskinesia in Cebus apella and Macaca speciosa monkeys: a review.

Two different studies were performed in subhuman primates in an attempt to induce symptoms of tardive dyskinesia. The first study lasted for over 5 years. This involved elderly Macaca speciosa. The animals were given first 25 mg of fluphenazine decanoate and later the enanthate IM (3.2 mg/kg) every 2 weeks and on 5 days a week, haloperidol, first IM and later PO. Haloperidol was given first in doses of 1.0 mg/kg and ultimately after years of therapy, in doses of 6.4 mg/kg per day. Those animals who survived gained weight to over 10 kg. After neuroleptic withdrawal, tardive dyskinesia became evident in 1 month. The symptoms of tardive dyskinesia following cessation of medication lasted a maximum of 1 year. This animal model produced very impressive symptoms in one of the three animals treated who survived. This is not a very practical animal model from the aspects of economics (costly), time (5 years), and animal availability (rare and endangered species). However, the symptoms of tardive dyskinesia are very striking and identical with human tardive dyskinesia in a susceptible animal. A more practical experimental animal model involved Cebus apella. Depot fluphenazine (0.1 to 3.2 mg/kg) was given continuously every 2 weeks for 1 year. In this species the symptoms of tardive dyskinesia became progressively prolonged and intense with each course of fluphenazine therapy and withdrawal, suggesting that reversible tardive dyskinesia may turn into irreversible tardive dyskinesia. With each succeeding course of fluphenazine therapy (1 month) and withdrawal (1-3 months), the animals appeared to be sensitized to both the acute extrapyramidal and the tardive dyskinesia symptoms. These animals were also given various experimental drug treatments including biperiden lactate, benztropine mesylate, and d-amphetamine after they developed signs of tardive dyskinesia.

Animals↗

Utilization and degradation of an ester-based synthetic lubricant by Acinetobacter lwoffi.

An oil-degrading bacterium, Acinetobacter lwoffi, isolated by elective culture from the Medway estuary, utilized an ester-based synthetic lubricating oil EMKARATE DE 155 as sole carbon and energy source. Analysis of culture supernatants by gas chromatography showed the accumulation of a nondegradable metabolite 1,1,1 Tris (hydroxymethyl)propane in addition to two metabolizable fatty acids, octanoic and decanoic acids as products of the synthetic oil degradation. Esterase activities were subsequently demonstrated in oil and acetate-grown cells. The synthetic oil therefore appears to be partially biodegradable in the environment.

Acinetobacter↗

Zuclopenthixol levels in serum and breast milk.

Breast milk and serum samples were obtained from six psychotic patients 3 days-10 months after delivery. Five of the women were given zuclopenthixol PO daily, and one was given zuclopenthixol decanoate IM every 2 weeks. Zuclopenthixol was estimated in breast milk and serum by high performance liquid chromatography. The zuclopenthixol levels in milk were found to be 29% of the serum levels on average. Based on the drug levels found in milk, the daily dose to a suckling infant was estimated to be 0.5-5 micrograms zuclopenthixol, corresponding to a dose of 0.01-0.1 mg to an adult. It is not likely that such a low dose would cause any effects or side effects in the infant unless infants are very different from adults concerning metabolism or sensitivity to the drug. The suckling infants included in this study were apparently not influenced by the intake of zuclopenthixol with the milk.

Adult↗

Adenosine triphosphate-dependent K currents activated by metabolic inhibition in rat ventricular myocytes differ from those elicited by the channel opener rilmakalim.

Adenosine triphosphate (ATP) dependent potassium channels (KATP channels) in heart ventricular muscle cells can be activated by depletion of intracellular ATP stores as well as by channel openers. In the present study we examined whether properties of KATP channels are dependent on the mode of activation. Whole-cell and single-channel currents were investigated by use of the patch-clamp technique in isolated ventricular rat myocytes. The channel opener rilmakalim dose dependently activated whole-cell currents [concentration for half-maximal activation (EC50) = 1.1 microM, Hill coefficient = 3.1, saturation concentration 10 microM]. Metabolic inhibition with 2-deoxy-D-glucose (10 mmol/l) also activated KATP currents after a time lag of several minutes. These currents were about two-fold higher than the rilmakalim-activated currents (rilmakalim-activated current 3.9 +/- 0.2 nA, 2-deoxy-D-glucose-activated current 8.1 +/- 0.9 nA; both recorded at 0 mV clamp potential). While the rilmakalim-activated current could be blocked completely and with high affinity by the sulphonylurea glibenclamide [concentration for half-maximal inhibition (IC50) = 8 nM, Hill coefficient = 0.7] the 2-deoxy-D-glucose-activated current could only be blocked partially (by maximally 46%) and higher glibenclamide concentrations were needed (IC50 = 480 nM, Hill coefficient = 0.8). The partial loss of blocking efficiency after metabolic inhibition was not restricted to glibenclamide but was also observed with the sulfonylureas glimepiride and HB 985, as well as with the non-sulfonylureas HOE 511 and 5-hydroxy-decanoate. Single-channel studies were in accordance with these whole-cell experiments. Both rilmakalim and metabolic inhibition with the uncoupler carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) activated single channels in the attached mode, where the number of current levels was significantly higher in the case of FCCP. Rilmakalim-activated channels were completely blocked by 10 microM glibenclamide, whereas several single-channel levels appeared in the presence of 100 microM glibenclamide after metabolic inhibition. In conclusion, after metabolic inhibition the amplitude of the activated KATP current is about twice as high as under saturating concentrations of the opener rilmakalim. Moreover, channels activated by metabolic inhibition lost part of their sensitivity to known channel blockers.

Adenosine Triphosphate↗

Plasma levels of fluphenazine and prolactin in psychiatric patients.

A total of 100 patients receiving fluphenazine (FPZ) decanoate for at least 12 months (96 schizophrenics and 4 other diagnoses) were investigated for plasma levels of FPZ and prolactin on the day of injection (day 0) and 7 days later (day 7). The plasma FPZ level significantly correlated with the weekly dose of FPZ. The plasma FPZ level per weekly FPZ dose multiplied by 100 (the FPZ ratio) showed a 20-fold variation. The FPZ ratio was significantly higher in the day- and in-patients (hospital-patients) than in out-patients. The plasma prolactin level significantly correlated with the plasma FPZ level but the prolactin to FPZ ratio negatively correlated with the plasma FPZ level. The prolactin to FPZ ratio was lower in the hospital patients than in the out-patients. This may suggest either that the high prolactin to FPZ ratio is an indicator of the therapeutic efficacy of FPZ or that there are at least two biologically distinct subgroups, one with a sharp prolactin response to FPZ, therefore with good prognosis, and another with the reverse direction.

Adult↗

Modification of nigral kainic acid-induced ipsilateral circling behaviour in the rat by neuroleptics and by contralateral caudate ablation.

A study was performed to examine possible changes in excitatory amino acid sensitivity within the pars reticulata of the rat substantia nigra as a result of neuroleptic exposure. Unilateral application of 20 ng kainic acid into caudal regions of the pars reticulata resulted in ipsilateral circling behaviour. This activity was significantly reduced 7 days after administration of the depot neuroleptic fluphenazine decanoate, 10.0 mg/kg SC, or 1 h after pretreatment with haloperidol, 0.1-1.0 mg/kg IP. The inhibitory effect of 0.1 mg/kg haloperidol was unaffected by prior ablation of the ipsilateral striatum, which by itself had no effect on the kainate-induced response. However, contralateral caudate ablation 21 days prior to intra-nigral kainate resulted in a markedly enhanced response, although 0.1 mg/kg haloperidol appeared to retain its inhibitory action when tested in such animals. The experimental data suggest a compensatory role of contralateral striatal mechanisms in nigral kainate-induced ipsilateral circling behaviour in the rat. Furthermore, they demonstrate at least a modulatory role of central dopaminergic mechanisms in such elicited behaviour. This latter action may involve multiple basal ganglia sites or, more probably, occur in other brain areas such as the mesolimbic system.

Animals↗

Early unwanted effects of fluphenazine esters related to plasma fluphenazine concentrations in schizophrenic patients.

Seven outpatients already receiving neuroleptic drugs by depot intramuscular injections were treated in two consecutive 3-week periods with 25 mg fluphenazine doses as enanthate and decanoate esters in a double-blind crossover study. They were assessed for incidence of akinesia, involuntary movement, autonomic disturbances and drowsiness, using a rating scale, and their blood pressures and pulse rates were recorded. Blood was collected for plasma fluphenazine and plasma prolactin assay. Additionally, a handwriting test was applied. A higher incidence of unwanted drug effects occurred when plasma fluphenazine concentrations were maximal, but this was not so with prolactin concentrations. No significant blood pressure changes occurred. Small increases in pulse rate and decreases in handwriting length occurred, but these changes were not associated with high fluphenazine levels.

Adult↗

Oral dyskinesia in rats following brain lesions and neuroleptic drug administration.

After 10-12 weeks of chronic haloperidol administration rats with frontal cortex ablations or lesions induced by intracerebroventricular infection of 6-hydroxydopamine developed vacuous chewing behavior at a fairly stable frequency (bifrontal ablations had 15-20, 6-hydroxy-dopamine lesioned rats 7-12 chewing movements/min). This behavior persisted for 10 weeks after the last injection of haloperidol decanoate. However, rats with frontal cortex lesions developed a low rate of vacuous chewings (4-8 chewings/min) even without haloperidol administration. Bilateral intrastriatal injections of kainic acid in combination with chronic haloperidol administration did not cause chewing movements in excess of unlesioned haloperidol-treated controls. Pharmacological tests of this animal model for tardive dyskinesia (TD) revealed similarities to human TD, but also differences. Dopamine agonists (apomorphine) and antagonists (haloperidol) both lowered chewing behavior analogous to reported effects on TD and so did gabaculine. The cholinergic drugs physostigmine and pilocarpine, however, increased chewing in rats, while anticholinergics (atropine) reduced it, in contrast to reported effects on human TD.

Acetylcholine↗

Nigral actions of GABA agonists are enhanced by chronic fluphenazine and differentiated by concomitant flurazepam.

Unilateral intranigral administration of baclofen (50-200 ng), muscimol (2.5--20 ng), or THIP (50--400 ng) in the rat led to contralateral circling behavior of a qualitatively similar nature. The potency of all three GABA-mimetics was enhanced in animals which had received the depot neuroleptic fluphenazine decanoate (10 mg/kg SC) 7 days prior to their intranigral administration. Significant differences between the nigral actions of the drugs could be demonstrated by their altered activity in the presence of a benzodiazepine. Flurazepam (500 ng) enhanced the intranigral potency of THIP, but reduced that of intranigral baclofen. Muscimol-induced circling behavior was unaffected by concomitant flurazepam. The data provide evidence for a functional supersensitivity of GABA-sensitive nondopaminergic projections from the substantia nigra in response to chronic neuroleptic treatment and reveal differences between the precise sites or modes of action of baclofen, muscimol, and THIP within this structure.

Animals↗