Cardiovascular and behavioral responses of gray wolves to ketamine-xylazine immobilization and antagonism by yohimbine

Adult wolves (Canis lupus) were immobilized with 6.6 mg/kg ketamine hydrochloride (KET) and 2.2 mg/kg xylazine hydrochloride (XYL) administered intramuscularly. Induction time was 4.6 +/- 0.3 min (mean +/- SE). Immobilization resulted in significant bradycardia and hypertension (P less than 0.05). Twenty min after induction, the wolves were given 0.05-0.60 mg/kg yohimbine hydrochloride (YOH). Yohimbine given intravenously produced dose-related increases in heart rate (HR) with doses greater than 0.15 mg/kg resulting in extreme tachycardia (greater than 300 bpm). All doses of YOH caused a temporary decrease in mean arterial blood pressure (MABP) with some individual animals manifesting profound hypotension (less than 30 torr) at doses greater than 0.15 mg/kg. Increasing the dose of YOH above 0.15 mg/kg did not significantly decrease either arousal or ambulation times. Administering YOH at 40 or 60 min after induction resulted in decreased arousal and ambulation times. Stimulation by weighing and taking repeated blood samples during anesthesia did not shorten arousal times. We recommend that wolves immobilized with XYL-KET be antagonized with doses of YOH less than 0.15 mg/kg.     

Pixe analysis of reproductive fluids

An external 3.8-MeV proton beam was employed to induce X-rays in 100-mg pellets of human follicular fluids and in 4–8 mg pellets of spermatozoa. The elements Cl, K, Ca, Fe, Cu, Zn, and Br were quantitatively determined in follicular fluids, whereas the elements, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn were determined in the spermatozoa. Both samples had high interelement Spearman correlation coefficients. Correlations of elements in the samples were observed with several clinical parameters. The multielemental analysis of spermatozoa can be used to approximate quantities of trace elements inserted into the egg ooplasm at the time of fertilization. These elemental quantities appear to be in the femtogram (10^?15) range.     

Mechanisms of growth inhibition by nonsteroidal antioestrogens in human breast cancer cells

Treatment of MCF7 human mammary carcinoma cells with the nonsteroidal antioestrogens, tamoxifen and clomiphene, leads to a concentration-dependent decrease in cellular proliferation rate which can be resolved into oestrogen-reversible and oestrogen-irreversible components. This became more clearly apparent when cells were treated with the 4-hydroxylated derivatives of these compounds where, because of enhanced affinity for the oestrogen receptor (ER), the dose-response curves for the two components could be separated. Thus treatment with 4-hydroxyclomiphene resulted in a distinct biphasic effect on cell growth. In the concentration range 10(-10)-10(-8) M, cell proliferation was inhibited in a concentration-dependent manner to a maximum of 60-70%, there was no further effect between 10(-8) and 10(-6) M, but at concentrations greater than 10(-6) M there was another concentration-dependent decrease in cell growth. Studies with a series of vinyl-substituted hydroxytriphenylethylenes revealed that in the nanomolar concentration range, where the effects of the drugs could be completely negated by the simultaneous addition of oestradiol, the potency for growth inhibition was highly correlated with affinity for ER. Such data provide strong evidence that in this concentration range the growth inhibitory effects of nonsteroidal antioestrogens are mediated by the intracellular ER. In the micromolar concentration range the effects of antioestrogens are not completely reversed by oestradiol, potency is not well correlated with affinity for either ER or the antioestrogen binding site (AEBS) but the effect is cell cycle phase-specific. Furthermore, the disparity between the affinity for AEBS (0.8-3.3 nM) and the concentration of drug needed for oestrogen-irreversible growth inhibition (greater than or equal to 2.5 microM) argue against a central role for AEBS in mediating this effect. The observation that triphenylethylene antioestrogens are calmodulin antagonists may provide some insight into potential mechanisms for this oestrogen-irreversible effect. Indeed, in identical experiments two phenothiazine calmodulin antagonists inhibited MCF 7 cell proliferation at concentrations greater than or equal to 2.5 x 10(-6) M. Growth inhibition following administration of fluphenazine, perphenazine and triphenylethylene antioestrogens was accompanied by qualitatively similar changes in the cell cycle kinetic parameters, i.e. accumulation in G1 phase at the expense of S phase cells. These data suggest triphenylethylene antagonism of calmodulin activated cellular processes as a potential mechanism for the oestrogen-irreversible effects of the nonsteroidal antioestrogens.     

Direct and Continuous Detection of ATP Secretion from Primary Monolayer Cultures of Bovine Adrenal Chromaffin Cells

A method was developed for direct and continuous detection of secretion of ATP from primary monolayer cultures of bovine adrenal chromaffin cells. ATP, which is costored with catecholamines within adrenal chromaffin cells, was released into the incubation medium, where it reacted with firefly luciferin-luciferase producing light detected by a photomultiplier located directly below the culture well. Acetylcholine, nicotine, the Ca2+ ionophore A23187, BaCl2, and KCl induced release of ATP. Induction of release of ATP by acetylcholine was dose dependent, with a threshold at 10(-7) M and a maximum at 10(-4) M. The dose-response curve for nicotine was bell shaped, with a threshold at 10(-7) M, a maximum at 10(-5) M, and diminished release at higher concentrations, an observation indicative of desensitization. Investigation of the initial rates of ATP secretion revealed that 10(-4) M nicotine actually induced release of ATP at a faster rate than 10(-5) M nicotine. However, the rate of ATP release evoked by 10(-4) M nicotine began to decline by 6 s, a result indicating the onset of receptor desensitization, whereas release induced by 10(-5) M nicotine continued unabated. Induction of release of ATP by acetylcholine or nicotine was biphasic, with a rapid, initial phase of release followed by a plateau at 0.5-1.5 min and a second phase of release beginning at 1.5-2 min, reaching a maximum by 2-3 min.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evidence of "cross-stressor"-induced adaptive gastric cytoprotection

Rats were given 7 days pre-treatment with either water (p.o.), 1 h immobilization or 20% ethanol (p.o.) with or without concomitant indomethacin injection. Following the pre-treatment phase, rats from each pre-treatment group were exposed to either 3 h cold-restraint stress or to 100% ethanol p.o. Results indicated that immobilization and 20% ethanol pre-treatment significantly reduced both cold-restraint stress ulcer formation and 100% ethanol-induced ulcers. Indomethacin co-treatment attenuated the reduction of ulcer formation of both pretreatments. These results suggest that "cross-stressor" adaptive cytoprotection occurs. Indomethacin abolished these effects, implicating the involvement of endogenous prostaglandins in the mediation of "cross-stressor"-induced gastric cytoprotection.     

Hormonal regulation of estradiol biosynthesis, aromatase activity, and aromatase mRNA in rat ovarian follicles and corpora lutea

To determine the molecular basis for changes in aromatase (P450arom) activity in rat ovarian follicles and corpora lutea, seven clones for rat P450arom cDNA have been identified and isolated from a rat granulosa cell λgtll cDNA expression library using a 62 mer deoxyoligonucleotide probe (derived from an amino acid sequence of purified human placental aromatase) and a human placental P450arom cDNA probe. One of the rat P450arom cDNA clones contained an insert 1.2 kb in size. Both the human 1.8 kb cDNA and the rat 1.2 kb cDNA probes hybridized to a single species of P450arom mRNA that was 2.6 kb in size. Northern blot analysis revealed that corpora lutea isolated on day 15 of pregnancy contained high amounts of P450arom mRNA, whereas granulosa cells of antral follicles of hormonally primed, hypophysectomized rats (i.e., those from which mRNA was isolated to construct the cDNA library) contained only low amounts of P450arom mRNA. The lower amounts of P450arom in granulosa cells of preovulatory follicles in the estradiol-follicle-stimulating hormone primed hypophysectomized rats were unexpected because follicles incubated in medium containing testosterone substrate produce more estradiol than do corpora lutea isolated on day 15 of pregnancy and incubated under similar conditions. Additional studies will determine the hormonal events responsible for the elevated amounts and constitutive maintenance of P450arom mRNA and aromatase activity in luteal cells in vivo and in vitro.     

Selective internalization of arachidonic acid by endothelial cells.

The asymmetric distribution of phospholipids in bovine endothelial-cell membranes was probed with 2,4,6-trinitrobenzenesulphonate and purified phospholipase A2. The data suggest that phosphotidylethanolamine is primarily located in the inner lipid bilayer, as reported for other cell types. Stearic acid is taken up by the endothelial cells and is randomly distributed among the membrane phospholipids. In contrast, the polyunsaturated fatty acids (arachidonic, eicosatrienoic and eicosapentaenoic acids) have initial incorporation into the phosphatidylcholine fraction. These fatty acids then undergo a time-dependent transfer from phosphatidylcholine to phosphatidylethanolamine. Thus we propose that endothelial cells possess a mechanism for the selective internalization of polyunsaturated fatty acids.     

Functional genes for cellobiose utilization in natural isolates of Escherichia coli.

The genes for utilization of cellobiose are normally cryptic in both laboratory strains and natural isolates of Escherichia coli. A survey of natural isolates of E. coli reveals that functional genes for cellobiose utilization, while rare, are present. The fraction of E. coli that utilized cellobiose ranged from less than 0.01% in human fecal samples to 7% in fecal samples obtained from horses. Samples obtained from sheep, cows, dogs, and pigs contained 0.1 to 0.5% cellobiose-positive E. coli. Neither the previously identified cel genes nor the bgl genes from E. coli K-12 were expressed during growth on cellobiose by any of the 14 naturally occurring Cel+ isolates that were tested. All of the naturally occurring Cel+ isolates possessed a cel operon, but all were deleted for the major portion of the bgl operon. The functional cel+ genes from these natural isolates differed from the mutationally activated cel+ genes obtained in earlier studies in that (i) the mutationally activated cel+ genes were temperature sensitive, while the functional genes were not, and (ii) transport of cellobiose was inducible in the strains carrying functional cel+ genes, while it was expressed constitutively in strains carrying mutationally activated genes.