ABSTRACT
We present a detailed analysis of the uncertainty in the neutron F(2n) structure function extracted from inclusive deuteron and proton deep-inelastic scattering data. The analysis includes experimental uncertainties as well as uncertainties associated with the deuteron wave function, nuclear smearing, and nucleon off-shell corrections. Correctly accounting for the Q(2) dependence of the data and calculations and restricting the nuclear corrections to microscopic models of the deuteron, we find a significantly smaller uncertainty in the extracted F(2n)/F(2p) ratio than in previous analyses. In addition to yielding an improved extraction of the neutron structure function, this analysis also provides an important baseline that can be compared to future, model-independent extractions of neutron structure to examine nuclear medium effects in the deuteron.
ABSTRACT
The behavioral and neurochemical consequences of the intrastriatal administration of 1-methyl-4-phenylpyridinium ion (MPP+), the toxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), were evaluated using the shuttlebox avoidance paradigm. MPP+ caused a significant depletion of striatal dopamine and significant disruption of shuttlebox performance. L-Dopa administration reversed both the dopamine depletion and the behavioral deficits. These observations are discussed in reference to the rodent-MPTP model of Parkinson's disease.
Subject(s)
Herbicides/toxicity , Levodopa/pharmacology , Pyridinium Compounds/toxicity , 1-Methyl-4-phenylpyridinium , Animals , Brain Chemistry/drug effects , Conditioning, Operant/drug effects , Male , Mice , Psychomotor Performance/drug effects , Pyridinium Compounds/antagonists & inhibitorsABSTRACT
This article deals with a broad overview of the incidence and treatment of dental anxiety and dental phobia. The dentist's position in this phenomenon is explored, and the basic psychological principles and modalities are discussed. This article serves to prepare the reader for the material presented in the ensuing articles.
Subject(s)
Anxiety/psychology , Dental Care/psychology , Fear , Anxiety/therapy , Humans , Phobic Disorders/psychology , Phobic Disorders/therapySubject(s)
Dental Service, Hospital , Phobic Disorders , Dental Care for Disabled , Dental Clinics , HumansSubject(s)
Dental Care/psychology , Dental Clinics , Fear , Anxiety/diagnosis , Anxiety/therapy , Behavior Therapy , Dentist-Patient Relations , HumansSubject(s)
Dental Care/psychology , Phobic Disorders/therapy , Adult , Aged , Desensitization, Psychologic , Female , Humans , Male , Patient Care Planning , Relaxation TherapyABSTRACT
1. [3H]Batrachotoxinin A-20-alpha-benzoate ([3H]BTX-B) and [3H]saxitoxin ([3H]STX), radioligands that bind to distinct sites on the voltage-sensitive sodium channel, were bound specifically to saturable sites in rainbow trout (Oncorhynchus mykiss) brain synaptoneurosomes. 2. Specific [3H]BTX-B binding was temperature dependent with highest levels of specific [3H]BTX-B binding observed at 7 degrees C. Specific binding was inversely correlated with assay temperature at temperatures above 7 degrees C. 3. Saturating concentrations of scorpion (Leiurus quinquestriatus) venom (ScV) stimulated specific [3H]BTX-B binding at 27 degrees C, but not at 7 degrees C. The dihydropyrazole insecticide RH 3421 inhibited specific [3H]BTX-B binding at 7 degrees C but had no effect on specific binding at 27 degrees C. The sodium channel activators veratridine and aconitine and the local anesthetic dibucaine inhibited specific [3H]BTX-B binding at both 7 degrees C and 27 degrees C. 4. Displacement experiments in the presence of ScV at 27 degrees C gave an equilibrium dissociation constant (KD) for [3H]BTX-B of 710 nM and a maximal binding capacity (Bmax) of 11.3 pmol/mg protein. Kinetic experiments established the rates of association (1.17 x 10(5) min-1 nM-1) and dissociation (0.0514 min-1) of the ligand-receptor complex. 5. The binding of [3H]STX reached apparent saturation at 7.5 nM. Scatchard analysis of the saturation data indicated a KD of 3.8 nM and a Bmax of 1.9 pmol/mg protein. 6. These studies provide evidence for high affinity, saturable binding sites for [3H]BTX-B and [3H]STX in trout brain preparations. Whereas certain neurotoxins modified the specific binding of [3H]BTX-B in trout brain synaptoneurosomes in a predictable fashion, other compounds known to affect specific [3H]BTX-B binding in mammalian brain preparations had no effect on specific [3H]BTX-B binding in the trout.