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Biomedical subjects

P Zeman

Publications and source records attributed to P Zeman.

34 records · Page 2Linked to original sources
PubMed1988

Surface skin lipids of birds--a proper host kairomone and feeding inducer in the poultry red mite, Dermanyssus gallinae.

A factor in bird skin responsible for D. gallinae feeding on its natural hosts was investigated. Both skin and plumage of chickens contained substance(s) attractive to mites which was easily dissolved in benzene derivates, amyl acetate or ethyl acetate, thermostabile up to 100 degrees C, nonvolatile, alkaline hydrolysable, and susceptible to oxidation. Components of surface skin lipids were ascertained to be the host-markers when using chromatographic separation and consecutive in vitro feeding technique for testing the isolates. Purified specific fowl diol esters of fatty acids prepared from the secretion of uropygial (preen) glands of hens were at least as effective a feeding stimulant for the mites as the natural extract of surface lipids of birds.

Animals↗
PubMed1988

Opioid mu and delta and dopamine receptor number changes in rat striatum during stress.

The question whether acute and repeated immobilization stress is accompanied by changes in the number of opioid mu- and delta- -receptor and that of dopamine receptor in the rat corpus striatum was studied. The number of opioid mu- and delta-receptors as well as that of dopamine receptors was estimated in corpus striatum of rats subjected either to a single (acute) immobilization stress (IMO) for 150 min or to identical repeated stress exposure for 7 or 40 consecutive days. The number of mu-receptors was estimated by the use of 3H-dihydromorphine binding (an agonist) or 3H-naloxone binding (an antagonist). Increased number of mu-receptors was found after acute IMO as estimated from the binding of both mu-specific ligands. However, the binding of 3H-dihydromorphine showed no changes after 7x and elevated mu-receptor number after 40x repeated IMO, although the binding of 3H-naloxone after 7x and 40x IMO was decreased. This paradoxical pattern might be explained by different affinity of both ligands to mu-receptor subpopulations (i.e. mu1- and mu2-receptors). In addition, the number of delta-receptors (assayed by 3H-D-Ala2,D-Leu5-enkephalin binding) was increased after acute as well as repeated (7x and 40x) IMO. The changes of dopamine receptor number (as measured from 3H-spiroperidol saturation analysis) correlated well with delta-receptor changes after 1x and 7x repeated IMO, but not after 40x IMO, since in the latter group the number of dopamine receptors decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Systemic efficacy of ivermectin against Dermanyssus gallinae (De Geer, 1778) in fowls.

The efficacy of ivermectin on females of a laboratory strain of Dermanyssus gallinae was tested. Ivermectin produced a noticeable systemic effect on the mites when inoculated intra-abdominally into infested chickens at rates greater than 0.6 mg kg-1. The concentrations efficacious against D. gallinae (1.8-5.4 mg kg-1) were unfavourably close to those causing toxicity in experimental birds (greater than or equal to 5.4 mg kg-1). Ivermectin administered at 5.4 mg kg-1 was active for 70 h post inoculation.

Animals↗
PubMed1987

Sympathoadrenal activity facilitates beta-endorphin and alpha-MSH secretion but does not potentiate ACTH secretion during immobilization stress.

The potential involvement of the sympathoadrenal system in stress-induced secretion of peptides from the intermediate lobe of the pituitary gland and the activation of the pituitary-adrenal axis was studied. Male Wistar rats were subjected to control procedures, to sympathectomy by chronic administration (8 weeks) of guanethidine and/or to medullectomy by adrenal enucleation 9 weeks prior to exposure to forced immobilization stress for various periods of time. In intact or sham-operated rats, immobilization caused a prompt increase of circulating norepinephrine, epinephrine (EPI), corticosterone and of immunoreactive adrenocorticotropic hormone (ACTHi), alpha-melanocyte-stimulating hormone (alpha-MSHi) and beta-endorphin (beta-ENDi). Peak levels of pituitary hormones were found after 10 min of stress exposure, but fell to less than 30% of these levels after 2.5 h of immobilization. Adrenal medullectomy, which abolished the stress-induced release of EPI, reduced the acute increase of plasma alpha-MSHi and beta-ENDi, but did not influence the acute increase of plasma ACTHi during immobilization stress. Also in medullectomized plus sympathectomized rats, the initial stress response of circulating ACTHi was not different from that of controls. Adrenal medullectomy with or without additional sympathectomy caused a marked increase in plasma ACTHi concentrations after prolonged stress exposure. We conclude that: catecholamines originating from the adrenalmedulla facilitate the stress-induced secretion of intermediate lobe peptides (alpha-MSHi, beta-ENDi); catecholamines from the sympathoadrenomedullary system do not contribute to the acute release of ACTH during immobilization stress; the sympathoadrenomedullary system is involved in the secondary reduction of circulating ACTHi levels seen during prolonged stress.

Adrenal Medulla↗
PubMed1987

Thermodynamic analysis of rat brain opioid mu-receptor-ligand interaction.

Opioid mu-receptors are membrane bound receptors. The mechanism by which they transduce their biological effect into the inner compartment of the postsynaptic cell is still not fully understood. The present study was attempted to the measurement of changes of the thermodynamic parameters of the receptor--agonist/antagonist interaction. We have set up the binding assays of a mu-receptor agonist (3H-dihydromorphine) as well as an antagonist (3H-naloxone). The saturation isotherms of both ligands have been assayed at various temperatures and from the resulting KD values the standard changes of Gibbs energy, enthalpy and entropy have been calculated. While the binding of the mu-receptor agonist 3H-dihydromorphine appears to be entropy driven (delta S0 = 230 J mol-1 K-1) and endothermic (delta H0 = 19 kJ mol-1), the binding of the mu-receptor antagonist 3H-naloxone is apparently driven by a decrease of standard enthalpy (delta H0 = -27 kJ mol-1; i.e. the reaction is exothermic) and is also characterized by an increase of standard entropy (delta S0 = 76 J mol-1 K-1). The maximal number of 3H-naloxone binding sites has to be determined by incubation at 0-4 degrees C. The present data to not support the view that opioid mu-receptors transduce their biological signal through the adenylatecyclase system by a mechanism similar to beta-adrenergically stimulated adenylatecyclase.

Adenylyl Cyclases↗
PubMed1987

Encounter the poultry red mite resistance to acaricides in Czechoslovak poultry-farming.

Poultry red mite susceptibility to permethrin, deltamethrin, tetramethrin, trichlorfon, fenitrothion, carbaryl and DDT, respectively, was screened within the territory of Bohemia by a method of diagnostic doses. The survey indicated widely spread resistance to DDT; in a few cases ineffectivity of permethrin, tetramethrin and trichlorfon, respectively, was also documented.

Animals↗
PubMed1985

The susceptibility of the poultry red mite, Dermanyssus gallinae (De Geer, 1778), to some acaricides under laboratory conditions.

Toxicity of 14 selected acaricides was tested for a laboratory strain of female D. gallinae. The most toxic were carbaryl (LC50 = 5.0 micrograms/m2), deltamethrin (LC50 = 7.8 micrograms/m2), bendiocarb (LC50 = 11.1 micrograms/m2), and permethrin (LC50 = 12.6 micrograms/m2). High level resistance to DDT in D. gallinae was recorded, with factors of resistance at LC50/LC90 reaching 57/73.

Animals↗
PubMed1985

Psychiatric triage.

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Crisis Intervention↗
PubMed1984

Solubilization and characterization of opioid binding sites from frog (Rana esculenta) brain.

Active opioid receptors were solubilized from frog (Rana esculenta) brain membrane fractions by the use of 1% digitonin. It was found by kinetic as well as by equilibrium measurements that both the membrane and the solubilized fractions contain two binding sites. For the membrane preparations, KD values were 0.9 and 3.6 nM, and Bmax values were 293 and 734 fmol/mg protein. For the solubilized preparations, KD values were 0.4 and 2.6 nM, an Bmax values were 35 and 266 fmol/mg protein. The stereospecificity of the binding did not change during solubilization. Both the membrane-bound and the solubilized receptors showed weak binding of enkephalin and mu-specific drugs, suggesting that they are predominantly of the kappa-type. The membrane-bound and the soluble receptors showed the same distribution of subtypes, i.e., 70% kappa, 13% mu, and 17% delta for the membrane-bound and 71% kappa, 17% mu, and 12% delta for the soluble receptors.

Animals↗