Recently proposed universality of the nonlinear response is put to the test and used to improve a previously designed model for xenon. Utilizing accurate measurements resolving the nonlinear polarization and ionization in time and space, we calibrate the scaling parameters of the model and demonstrate agreement with several experiments spanning the intensity range relevant for applications in nonlinear optics at near-infrared and mid-infrared wavelengths. Applications to other species including small molecules are discussed, suggesting a self-consistent way to calibrate light-matter interaction models.
View Article and Find Full Text PDFThe optical Kerr effect, and the nonlinear polarization in general, represents an important light-matter interaction governing many regimes encountered in the nonlinear optics. We reason that in the context of optical filamentation one should distinguish the third-order Kerr effect occurring at relatively low light intensities from the effective Kerr nonlinearity relevant to higher intensity. While many properties of filaments can be captured well with a third-order nonlinear polarization model with a nonlinear index chosen somewhat higher than the true nonlinear index operative at low intensities, our comparative simulations indicate that some filamentation aspects carry significant signatures from the higher-order nonlinearity.
View Article and Find Full Text PDFStimulation of prostate growth is a major concern with testosterone therapy in older hypogonadal men. As a result, nonsteroidal selective androgen receptor modulators with anabolic activity but less prostate stimulation are being developed. Anabolic steroids might exhibit similar tissue selectivity.
View Article and Find Full Text PDFObjective: To identify herbal product use in a dialysis population.
Design And Setting: Cross-sectional survey conducted at 2 freestanding dialysis centers in Northwest Ohio.
Patients: Two hundred and sixteen hemodialysis and peritoneal dialysis patients who provided informed consent.
These studies evaluated neurotoxic and pharmacologic properties of the R(+) and S(-) enantiomers of methcathinone, a psychostimulant drug that has surfaced in the illicit drug market, primarily in the S(-) form. Neurotoxic potential toward brain dopamine (DA) and serotonin (5-HT) neurons was assessed by measuring DA and 5-HT axonal markers and by means of silver degeneration studies; pharmacologic effects were evaluated by measuring locomotor stimulation. Methcathinone produced dose-related neurotoxic and locomotor stimulant effects which were species- and enantiomer-dependent.
View Article and Find Full Text PDFThe radioprotectant, dithiothreitol (DTT) has been shown to increase excitability in the hippocampal slice preparation. In the present study, intracellular recording techniques were used to further examine the actions of DTT. Electrophysiological recordings from CA1 pyramidal cells were obtained prior to, during and after DTT exposure.
View Article and Find Full Text PDFTo investigate the effects of ionizing radiation on an isolated neuronal network without complicating systemic factors, slices of hippocampus from the guinea pig were isolated and studied in vitro. Slices were irradiated with a 60Co source and compared to paired, sham-irradiated controls. Electrophysiological activity in the CA 1 population of pyramidal cells was evoked by stimulation of the stratum radiatum.
View Article and Find Full Text PDFDithiothreitol (DTT) is a sulfhydryl reducing agent used as a radioprotectant. Exposure of hippocampal slices for 30 min to 0.5 mM DTT irreversibly increased the orthodromic population spike amplitude, promoted repetitive firing and induced spontaneous epileptiform activity in the CA1 subfield.
View Article and Find Full Text PDFThe subarachnoid injection of gentamicin into rats causes a transient flaccid paralysis of the hindlimbs lasting 1 to 5 hrs followed by a permanent flaccid paralysis which develops after 24 to 36 hrs. Although the early transient paralysis could be attributed to a pharmacologic blockade of central synaptic transmission, the mechanism of the blockade was not apparent. This study examines the effects of gentamicin and two other aminoglycoside antibiotics, kanamycin and neomycin, on reflex transmission in the isolated, hemisected spinal cord of the neonatal rat and the interaction with calcium.
View Article and Find Full Text PDFThe intrathecal injection of gentamicin into a human patient with gram-negative bacterial meningitis as well as its intracisternal injection into rabbits caused spongy-like lesions in the gray matter and tetraplegia in rabbits. To characterize this neurotoxic effect, gentamicin was injected into the subarachnoid space of the lumbar spinal cord of the rat. A biphasic hindlimb paralysis ensued which consisted at first of a transient flaccid paralysis lasting 1 to 5 hr followed by a permanent flaccid paralysis which developed after 24 to 36 hr.
View Article and Find Full Text PDFThe characteristics of atropine-sensitive binding of l-[3H]-quinuclidinyl benzilate ([3H]-QNB) to membrane suspensions of sheep posterior pituitary indicate that the binding sites represent muscarinic cholinergic receptors. Scatchard plots of 6 saturation experiments showed a single class of binding sites, with an equilibrium dissociation constant of 16 +/- 2 pM and a density equivalent to 1.8 +/- 0.
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