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J L Price

Publications and source records attributed to J L Price.

At least 19 recordsLinked to original sources
PubMed2006

Discrimination of photon from proton irradiation using glow curve feature extraction and vector analysis.

Two types of thermoluminescence dosemeters (TLDs), the Harshaw LiF:Mg,Ti (TLD-100) and CaF(2):Tm (TLD-300) were investigated for their glow curve response to separate photon and proton irradiations. The TLDs were exposed to gamma irradiation from a (137)Cs source and proton irradiation using a positive ion accelerator. The glow curve peak structure for each individual TLD exposure was deconvolved to obtain peak height, width, and position. Simulated mixed-field glow curves were obtained by superposition of the experimentally obtained single field exposures. Feature vectors were composed of two kinds of features: those from deconvolution and those taken in the neighbourhood of several glow curve peaks. The inner product of the feature vectors was used to discriminate among the pure photon, pure proton and simulated mixed-field irradiations. In the pure cases, identification of radiation types is both straightforward and effective. Mixed-field discrimination did not succeed using deconvolution features, but the peak-neighbourhood features proved to discriminate reliably.

Algorithms↗
PubMed2003

Job satisfaction of hospital nurses: an empirical test of a causal model in Taiwan.

AIM: The purpose of this research was to empirically test a model of job satisfaction in Taiwan. METHODS: The model represents a revision of the Price-Mueller model, which is based on empirical research conducted since 1972 at the University of Iowa. This empirical test contributes to the generalization, on cross-national settings, of results from American-based research on job satisfaction. FINDINGS: The results, based on a sample of 308 non-supervisory hospital nurses in Taiwan, indicate that 45% of the variance in job satisfaction was accounted for by the revised model. The work characteristic variable "routinization" had the greatest impact on job satisfaction, followed by the personality traits "positive affectivity" and "job involvement". Although it is difficult to change the routine nature of nursing, the manager should make efforts to diversify the job description and empower his/her subordinates. CONCLUSIONS: It is suggested that having information on a nurse's personality will help to predict her/his future job satisfaction and may lead to improved selection of personnel. In addition, different management styles or reward systems that are sensitive to different personalities should be carefully studied and implemented, as appropriate.

Humans↗
PubMed2002

Feasibility of a neutron detector-dosemeter based on single-event upsets in dynamic random-access memories.

The feasibility was investigated of a solid-state neutron detector/dosemeter based on single-event upset (SEU) effects in dynamic random-access memories (DRAMs), commonly used in computer memories. Such a device, which uses a neutron converter material to produce a charged particle capable of causing an upset, would be light-weight, low-power, and could be read simply by polling the memory for bit flips. It would have significant advantages over standard solid-state neutron dosemeters which require off-line processing for track etching and analysis. Previous efforts at developing an SEU neutron detector/dosemeter have suffered from poor response, which can be greatly enhanced by selecting a modern high-density DRAM chip for SEU sensitivity and by using a thin 10B film as a converter. Past attempts to use 10B were not successful because the average alpha particle energy was insufficient to penetrate to the sensitive region of the memory. This can be overcome by removing the surface passivation layer before depositing the 10B film or by implanting 10B directly into the chip. Previous experimental data show a 10(3) increase in neutron sensitivity by chips containing borosilicate glass, which could be used in an SEU detector. The results are presented of simulations showing that the absolute efficiency of an SEU neutron dosemeter can be increased by at least a factor of 1000 over earlier designs.

Computer Storage Devices↗
PubMed2002

Glow curve analysis applied to the discrimination of X ray versus proton irradiation.

Three types of thermoluminescence dosemeters (TLDs): LiF:Mg,Ti (TLD-100), CaF2:Tm (TLD-300), and alpha-Al2O3:C (TLD-500), were investigated for their glow curve response to separate X ray and proton irradiations. The glow curve structure for each individual TLD's exposure to the X ray and proton irradiations was analysed and compared. Distinguishable differences between the glow curve structure characteristic of each type of radiation were observed. The proton TLD-100 glow curve has revealed a complex high-temperature peak structure that was used for the proton/X ray discrimination algorithm. Proton irradiation of TLD-300 resulted in an apparent switch in the relative heights of peaks 3 and 5 as compared to X ray. In TLD-500, proton irradiation produced a more subtle difference in the glow curve with an increase in the ratio between high- and low-temperature peaks. Results demonstrate promising differences in glow curve structure present allowing for discrimination between X ray and proton radiation field exposures.

Calcium Fluoride↗
PubMed2001

The Drosophila double-timeS mutation delays the nuclear accumulation of period protein and affects the feedback regulation of period mRNA.

The Drosophila double-time (dbt) gene, which encodes a protein similar to vertebrate epsilon and delta isoforms of casein kinase I, is essential for circadian rhythmicity because it regulates the phosphorylation and stability of period (per) protein. Here, the circadian phenotype of a short-period dbt mutant allele (dbt(S)) was examined. The circadian period of the dbt(S) locomotor activity rhythm varied little when tested at constant temperatures ranging from 20 to 29 degrees C. However, per(L);dbt(S) flies exhibited a lack of temperature compensation like that of the long-period mutant (per(L)) flies. Light-pulse phase-response curves were obtained for wild-type, the short-period (per(S)), and dbt(S) genotypes. For the per(S) and dbt(S) genotypes, phase changes were larger than those for wild-type flies, the transition period from delays to advances was shorter, and the light-insensitive period was shorter. Immunohistochemical analysis of per protein levels demonstrated that per protein accumulates in photoreceptor nuclei later in dbt(S) than in wild-type and per(S) flies, and that it declines to lower levels in nuclei of dbt(S) flies than in nuclei of wild-type flies. Immunoblot analysis of per protein levels demonstrated that total per protein accumulation in dbt(S) heads is neither delayed nor reduced, whereas RNase protection analysis demonstrated that per mRNA accumulates later and declines sooner in dbt(S) heads than in wild-type heads. These results suggest that dbt can regulate the feedback of per protein on its mRNA by delaying the time at which it is translocated to nuclei and altering the level of nuclear PER during the declining phase of the cycle.

Alleles↗
PubMed2001

Orbitomedial prefrontal cortical projections to hypothalamus in the rat.

A previous study in the rat revealed that distinct orbital and medial prefrontal cortical (OMPFC) areas projected to specific columns of the midbrain periaqueductal gray region (PAG). This study used anterograde tracing techniques to define projections to the hypothalamus arising from the same OMPFC regions. In addition, injections of anterograde and retrograde tracers were made into different PAG columns to examine connections between hypothalamic regions and PAG columns projected upon by the same OMPFC regions. The most extensive patterns of hypothalamic termination were seen after injection of anterograde tracer in prelimbic and infralimbic (PL/IL) and the ventral and medial orbital (VO/MO) cortices. Projections from rostral PL/IL and VO/MO targeted the rostrocaudal extent of the lateral hypothalamus, as well as lateral perifornical, and dorsal and posterior hypothalamic areas. Projections arising from caudal PL/IL terminated within the dorsal hypothalamus, including the dorsomedial nucleus and dorsal and posterior hypothalamic areas. There were also projections to medial perifornical and lateral hypothalamic areas. In contrast, it was found that anterior cingulate (AC), dorsolateral orbital (DLO), and agranular insular (AId) cortices projected to distinct and restricted hypothalamic regions. Projections arising from AC terminated within dorsal and posterior hypothalamic areas, whereas DLO and AId projected to the lateral hypothalamus. The same OMPFC regions also projected indirectly, by means of specific PAG columns, to many of the same hypothalamic fields. In the context of our previous findings, these data indicate that, in both rat and macaque, parallel but distinct circuits interconnect OMPFC areas with specific hypothalamic regions, as well as PAG columns.

Animals↗
PubMed2001

Absence of cognitive impairment or decline in preclinical Alzheimer's disease.

OBJECTIVE: To determine whether clinically nondemented elderly individuals with pathologically confirmed preclinical AD are characterized by cognitive decline as measured by psychometric tests before death. METHODS: Psychometric performance was examined retrospectively in 14 individuals who were nondemented at time of death and grouped in accordance with their neuropathologic findings: 1) Healthy brain (n = 9) was characterized by the absence of senile plaques or by only patchy neocortical deposits of plaques; 2) preclinical AD (n = 5) was characterized by neuritic and diffuse plaques distributed throughout the neocortex. All individuals showed neurofibrillary pathologic change in medial temporal lobe structures. For comparison, we also evaluated 10 individuals who died in the earliest symptomatic stage of dementia of the Alzheimer type (DAT). All individuals had been assessed by clinical and psychometric measures during life. The psychometric measures yielded a standardized factor score that represented global cognitive performance. RESULTS: At the last assessment before death, individuals with very mild DAT were impaired on the factor score and on individual psychometric measures with respect to the nondemented individuals. Those nondemented individuals with preclinical AD did not differ in performance from those with healthy brains. For individuals with at least three psychometric assessments during life, there was no decline in performance for either those with healthy brains (n = 5) or preclinical AD (n = 3), although decline was evident for very mild DAT individuals (n = 5). CONCLUSIONS: Pathologically confirmed preclinical AD is not associated with cognitive impairment or decline, even on measures shown to be sensitive to very mild DAT.

Aged↗
PubMed2001

Amphetamine-induced dopamine release in human ventral striatum correlates with euphoria.

BACKGROUND: Studies in experimental animals have implicated the mesolimbic dopaminergic projections into the ventral striatum in the neural processes underlying behavioral reinforcement and motivated behavior; however, understanding the relationship between subjective emotional experience and ventral striatal dopamine (DA) release has awaited human studies. Using positron emission tomography (PET), we correlated the change in endogenous dopamine concentrations following dextroamphetamine (AMPH) administration with the associated hedonic response in human subjects and compared the strength of this correlation across striatal subregions. METHODS: We obtained PET measures of [(11)C]raclopride specific binding to DA D2/D3 receptors before and after AMPH injection (0.3 mg/kg IV) in seven healthy subjects. The change in [(11)C]raclopride binding potential (DeltaBP) induced by AMPH pretreatment and the correlation between DeltaBP and the euphoric response to AMPH were compared between the anteroventral striatum (AVS; comprised of accumbens area, ventromedial caudate, and anteroventral putamen) and the dorsal caudate (DCA) using an MRI-based region of interest analysis of the PET data. RESULTS: The mean DeltaBP was greater in the AVS than in the DCA (p <.05). The AMPH-induced changes in euphoria analog scale scores correlated inversely with DeltaBP in the AVS (r = -.95; p <.001), but not in the DCA (r =.30, ns). Post hoc assessments showed that changes in tension-anxiety ratings correlated positively with DeltaBP in the AVS (r =.80; p [uncorrected] <.05) and that similar relationships may exist between DeltaBP and emotion ratings in the ventral putamen (as were found in the AVS). CONCLUSIONS: The preferential sensitivity of the ventral striatum to the DA releasing effects of AMPH previously demonstrated in experimental animals extends to humans. The magnitude of ventral striatal DA release correlates positively with the hedonic response to AMPH.

Adult↗
PubMed2001

Mild cognitive impairment represents early-stage Alzheimer disease.

BACKGROUND: Mild cognitive impairment (MCI) is considered to be a transitional stage between aging and Alzheimer disease (AD). OBJECTIVE: To determine whether MCI represents early-stage AD by examining its natural history and neuropathologic basis. DESIGN: A prospective clinical and psychometric study of community-living elderly volunteers, both nondemented and minimally cognitively impaired, followed up for up to 9.5 years. Neuropathologic examinations were performed on participants who had undergone autopsy. SETTING: An AD research center. PARTICIPANTS: All participants enrolled between July 1990 and June 1997 with Clinical Dementia Rating (CDR) scores of 0 (cognitively healthy; n = 177; mean age, 78.9 years) or 0.5 (equivalent to MCI; n = 277; mean age, 76.9 years). Based on the degree of clinical confidence that MCI represented dementia of the Alzheimer type (DAT), 3 subgroups of individuals with CDR scores of 0.5 were identified: CDR 0.5/DAT, CDR 0.5/incipient DAT, and CDR 0.5/uncertain dementia. MAIN OUTCOME MEASURE: Progression to the stage of CDR 1, which characterizes mild definite DAT. RESULTS: Survival analysis showed that 100% of CDR 0.5/DAT participants progressed to greater dementia severity over a 9.5-year period. At 5 years, rates of progression to a score of CDR 1 (or greater) for DAT were 60.5% (95% confidence interval [CI], 50.2%-70.8%) for the CDR 0.5/DAT group, 35.7% (95% CI, 21.0%-50.3%) for the CDR 0.5/incipient DAT group, 19.9% (95% CI, 8.0%-31.8%) for the CDR 0.5/uncertain dementia group, and 6.8% (95% CI, 2.2%-11.3%) for CDR 0/controls. Progression to greater dementia severity correlated with degree of cognitive impairment at baseline. Twenty-four of the 25 participants with scores of CDR 0.5 had a neuropathologic dementing disorder, which was AD in 21 (84%). CONCLUSIONS: Individuals currently characterized as having MCI progress steadily to greater stages of dementia severity at rates dependent on the level of cognitive impairment at entry and they almost always have the neuropathologic features of AD. We conclude that MCI generally represents early-stage AD.

Aged↗
PubMed2001

Neuron number in the entorhinal cortex and CA1 in preclinical Alzheimer disease.

OBJECTIVES: To determine whether nondemented subjects with pathological evidence of preclinical Alzheimer disease (AD) demonstrate neuronal loss in the entorhinal cortex and hippocampus, and whether the onset of cognitive deficits in AD coincides with the onset of neuronal degeneration. METHODS: Preclinical AD cases have been defined by the absence of cognitive decline but with neuropathological evidence of AD. The hippocampus and entorhinal cortex were examined in 13 nondemented cases (Clinical Dementia Rating [CDR] 0) with healthy brains, 4 cases with preclinical AD, 8 cases with very mild symptomatic AD (CDR 0.5), and 4 cases with severe AD (CDR 3, hippocampus only). The volume and number of neurons were determined stereologically in 2 areas that are vulnerable to AD--the entorhinal cortex (as a whole and layer II alone) and hippocampal field CA1. RESULTS: There was no significant decrease in neuron number or volume with age in the healthy nondemented group and little or none between the healthy and preclinical AD groups. Substantial decreases were found in the very mild AD group in neuron number (35% in the entorhinal cortex, 50% in layer II, and 46% in CA1) and volume (28% in the entorhinal cortex, 21% in layer II, and 29% in CA1). Greater decrements were observed in CA1 in the severe AD group. CONCLUSIONS: There is little or no neuronal loss in aging or preclinical AD but substantial loss in very mild AD. The findings indicate that AD results in clinical deficits only when it produces significant neuronal loss.

Aged↗
PubMed2001

A review of individual psychotherapy outcomes for adult survivors of childhood sexual abuse.

This review examines the current literature on individual psychotherapy outcomes with adult survivors of childhood sexual abuse. As compared to the literature on treatment with victims of sexual trauma in adulthood, fewer researchers have explored the field of psychotherapy outcome with this population, particularly with regard to individual treatments. For this reason, a review of psychotherapy outcome for adult survivors of child sexual abuse is needed. This review first presents issues salient to the study of treatment with this population, such as prevalence, short-term impact, and long-term sequelae of childhood sexual trauma. Next, the eight studies that have been published on individual psychotherapy for this population are presented and evaluated according to both efficacy and effectiveness criteria for a methodologically sound study. Last, directions for future research with this population include continued integration of efficacy and effectiveness methodology, use of multi-method/multi-rater assessment data, as well as further investigation of interpersonal variables such as the therapeutic alliance.

Child↗
PubMed2001

Pathologic correlates of nondemented aging, mild cognitive impairment, and early-stage Alzheimer's disease.

The results of studies from the Washington University Alzheimer Disease (AD) Research Center and those from other centers and investigators regarding the neuropathologic correlates of normal aging and early-stage AD are reviewed. We conclude that widespread amyloid plaques in the neocortex best distinguishes very early stage AD, including "MCI" stage, and preclinical stages, from healthy brain aging. Other AD lesions, including increased formation of neurofibrillary tangles and neuronal degeneration appear to result from the amyloid-initiated pathologic process, although they may have a more immediate effect on expression and severity of dementia. These data provide strong support for anti-amyloid intervention as a preventive therapy for AD. It is now critical to develop methods to detect preclinical AD during life.

Aged↗
PubMed2000

Prefrontal cortical projections to the striatum in macaque monkeys: evidence for an organization related to prefrontal networks.

The organization of projections from the prefrontal cortex (PFC) to the striatum in relation to previously defined "orbital" and "medial" networks within the PFC were studied in monkeys using anterograde and retrograde tracing techniques. The results indicate that the orbital and medial networks connect to different striatal regions. The ventromedial striatum (the medial caudate nucleus, accumbens nucleus, and ventral putamen) receives input predominantly from the medial PFC (mPFC) and orbital areas 12o, Iai, and 13a, which constitute the "medial" network. More specifically, caudal medial areas 32, 25, and 14r project to the medial edge of the caudate nucleus, accumbens nucleus, and ventromedial putamen, whereas rostral areas 10o, 10m, and 11m are restricted to the medial edge of the caudate. Projections from orbital areas 12o, 13a, and Iai extend more laterally into the lateral accumbens and the ventral putamen. Area 24 gives rise to a divided pattern of projections, including fibers to the ventromedial striatum, apparently from area 24b, and fibers to the dorsolateral striatum, apparently from area 24c. Other areas of orbital cortex (11l, 12m, 12l, 13m, 13l, Ial, and Iam) that constitute the "orbital" network project primarily to the central part of the rostral striatum. This region includes the central and lateral parts of the caudate nucleus, and the ventromedial putamen, on either side of the internal capsule. The results support the subdivision of the orbital and medial PFC into "medial" and "orbital" networks and suggest that the prefrontostriatal projections reflect the functional organization of the PFC rather than topographic location.

Animals↗
PubMed2000

Orbitomedial prefrontal cortical projections to distinct longitudinal columns of the periaqueductal gray in the rat.

We utilised retrograde and anterograde tracing procedures to study the origin and termination of prefrontal cortical (PFC) projections to the periaqueductal gray (PAG) in the rat. A previous study, in the primate, had demonstrated that distinct subgroups of PFC areas project to specific PAG columns. Retrograde tracing experiments revealed that projections to dorsolateral (dlPAG) and ventrolateral (vlPAG) periaqueductal gray columns arose from medial PFC, specifically prelimbic, infralimbic, and anterior cingulate cortices. Injections made in the vlPAG also labeled cells in medial, ventral, and dorsolateral orbital cortex and dorsal and posterior agranular insular cortex. Other orbital and insular regions, including lateral and ventrolateral orbital, ventral agranular insular, and dysgranular and granular insular cortex did not give rise to appreciable projections to the PAG. Anterograde tracing experiments revealed that the projections to different PAG columns arose from specific PFC areas. Projections from the caudodorsal medial PFC (caudal prelimbic and anterior cingulate cortices) terminated predominantly in dlPAG, whereas projections from the rostroventral medial PFC (rostral prelimbic cortex) innervated predominantly the vlPAG. As well, consistent with the retrograde data, projections arising from select orbital and agranular insular cortical areas terminated selectively in the vlPAG. The results indicate: (1) that rat orbital and medial PFC possesses an organisation broadly similar to that of the primate; and (2) that subdivisions within the rat orbital and medial PFC can be recognised on the basis of projections to distinct PAG columns.

Animals↗
PubMed2000

Effects of excitotoxic lesions in the ventral striatopallidal--thalamocortical pathway on odor reversal learning: inability to extinguish an incorrect response.

The role of the ventral striatopallidal pathway and related cortical areas in stimulus-reward association reversal behavior was studied by inducing bilateral lesions with the excitotoxin, N-methyl-D-aspartate (NMDA) at restricted sites in the system. The areas lesioned were the ventral pallidum (VP), the ventral striatum (VS), the medial prefrontal cortex (mPFC) [i.e., the prelimbic (PL) and infralimbic (IL) cortexes], and the orbital cortex [i.e., the dorsolateral orbital (DLO), ventral lateral orbital (VLO), and lateral orbital (LO) cortexes]. Rats with lesions of the dorsal caudate nucleus and putamen (CPu) served as a positive control in this study. Water-deprived rats were trained on a go, no-go two-odor olfactory discrimination task to respond to one odor (S+) with water as a reward and to suppress responding to the other odor (S-). The rats were then tested for their ability to reverse the associated stimuli. The number of errors made before successfully learning the stimulus-reward association were measured in relation to a sham lesion control group which did not receive injections of NMDA. In experimental rats, the lesions did not affect their ability to learn stimulus-reward associations for novel odors, but did result in an increase in the number of false alarms after the significance of the associated stimuli were reversed. That is, the lesioned animals persisted in responding to the formerly rewarded but now unrewarded stimulus. Rats with damage to the CPu did not show a significant effect when compared with the controls during reversal problems. The results support the hypothesis that the ventral striatopallidal system, together with related thalamic and frontal cortical structures, functions in reversal learning by suppressing inappropriate responses to stimuli that are no longer rewarded.

Animals↗
PubMed2000

The organization of networks within the orbital and medial prefrontal cortex of rats, monkeys and humans.

This paper reviews architectonic subdivisions and connections of the orbital and medial prefrontal cortex (OMPFC) in rats, monkeys and humans. Cortico-cortical connections provide the basis for recognition of 'medial' and 'orbital' networks within the OMPFC. These networks also have distinct connections with structures in other parts of the brain. The orbital network receives sensory inputs from several modalities, including olfaction, taste, visceral afferents, somatic sensation and vision, which appear to be especially related to food or eating. In contrast, the medial network provides the major cortical output to visceromotor structures in the hypothalamus and brainstem. The two networks have distinct connections with areas of the striatum and mediodorsal thalamus. In particular, projections to the nucleus accumbens and the adjacent ventromedial caudate and putamen arise predominantly from the medial network. Both networks also have extensive connections with limbic structures. Based on these and other observations, the OMPFC appears to function as a sensory-visceromotor link, especially for eating. This linkage appears to be critical for the guidance of reward-related behavior and for setting of mood. Imaging and histological observations on human brains indicate that clinical depressive disorders are associated with specific functional and cellular changes in the OMPFC, including activity and volume changes, and specific changes in the number of glial cells.

Animals↗