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D Pierson

Publications and source records attributed to D Pierson.

16 recordsLinked to original sources
PubMed2001

Mapping of the water quality of Lake Erken, Sweden, from imaging spectrometry and Landsat Thematic Mapper.

Hyperspectral data have been collected by the Compact Airborne Spectrographic Imager (CASI) and multispectral data by the Landsat Thematic Mapper (TM) instrument for the purpose of mapping lake water quality. Field campaigns have been performed on Lake Erken in Sweden during the summer of 1997. Water samples have been collected and analysed in laboratory. Continuously measured variables from a boat have added a spatial dimension to the ground truth dataset. The data have been used to construct algorithms, based on remotely sensed data, for the retrieval of water quality parameters. The correlation between the continuous data and the collected CASI data has been investigated. Algorithms using both the point sampling results and the continuous data have been developed. Maps based on data from each instrument, showing the distribution of chlorophyll, are presented. Problems of having few water sampling stations, and the potential of using sub-water optics models are addressed as well. Tests were performed on MERIS bands and found useful for mapping chlorophyll and turbidity, and algorithms have been suggested for future use with MERIS.

Algorithms↗
PubMed2000

Mapping of quantitative trait loci for ethanol preference in quasi-congenic strains.

Ethanol preference, a component of alcoholism, has been known for four decades to differ greatly between C57BL/6 and BALB/c inbred mouse strains. For mapping quantitative trait loci (QTLs) that affect ethanol preference, we used a set of B6.C Recombinant QTL Introgression (RQI) strains, which carry about 5% of the donor BALB/cJ (C) genome on a C57BL/6ByJ (B6) background. After characterizing males of the progenitor and RQI strains for variations in ethanol preference, we scanned their genome for polymorphisms at 244 dinucleotide-repeat marker loci known to differ between B6 and C. Because of the introgression of BALB/c-type QTLs onto the B6 background, some strains showed ethanol preference significantly lower or higher than that of the background strain, suggesting that genetic interaction between ethanol preference QTLs and the background can be operative. The genomic region showing the strongest influence on ethanol preference was on mouse chromosome 15, and corresponds to human chr.12q11-q13.

Alcohol Drinking↗
PubMed1998

Prolactin response to electroconvulsive therapy: effects of electrode placement and stimulus dosage.

BACKGROUND: It is unclear whether the serum prolactin (PRL) surge following electroconvulsive therapy (ECT) is a marker of optimal ECT administration. We investigated the relations among PRL surge, stimulus parameters, and outcome in major depressive disorder (MDD). METHODS: Seventy-nine patients with MDD were randomized in a double-blind trial to right unilateral (RUL) or bilateral (BL), and to low-dose (just above seizure threshold) or high-dose (2.5 x threshold) ECT. RESULTS: Change in PRL (delta PRL) varied among treatment groups, with significant effects of electrode placement (BL > RUL, p < .006), electrical dosage (high > low, p < .04), and gender (female > male, p < .005). There was no evidence that clinical improvement was associated with greater PRL surge. CONCLUSIONS: Although delta PRL varied with parameters impacting on response rates, these data indicate the PRL surge cannot serve as a useful index of clinically effective treatment. This finding does not support the view that diencephalic seizure propagation is necessary for ECT to exert therapeutic effects.

Adult↗
PubMed1998

Temporal control in rats: analysis of nonlocalized effects from short interfood intervals.

The present experiment analyzed temporal control of postreinforcement pause duration during within-session changes in the criterion for reinforcement (interfood interval, IFI). Analysis of interval-by-interval changes in the pause revealed localized and nonlocalized effects from short intervals that caused specific changes in performance. In Phase 1, rats were presented with five consecutive 15-s IFIs intercalated into a series of 60-s IFIs. The 15-s set decreased the pause in adjacent and more remote 60-s intervals. In Phase 2, two sets of 15-s intervals were intercalated. The spacing between the two sets varied so that 0, 5, 10, or 15 60-s IFIs separated the sets. The postreinforcement pause tracked all changes in the IFI duration, and the localized effect from a short set extended beyond the next interval to the next few 60-s IFIs. Effects from one set, however, did not combine with a second set: Changes in the pause after two sets were the same regardless of the spacing between sets.

Animals↗
PubMed1994

Bistability and the dynamics of periodically forced sensory neurons.

Many neurons at the sensory periphery receive periodic input, and their activity exhibits entrainment to this input in the form of a preferred phase for firing. This article describes a modeling study of neurons which skip a random number of cycles of the stimulus between firings over a large range of input intensities. This behavior was investigated using analog and digital simulations of the motion of a particle in a double-well with noise and sinusoidal forcing. Well residence-time distributions were found to exhibit the main features of the interspike interval histograms (ISIH) measured on real sensory neurons. The conditions under which it is useful to view neurons as simple bistable systems subject to noise are examined by identifying the features of the data which are expected to arise for such systems. This approach is complementary to previous studies of such data based, e.g., on non-homogeneous point processes. Apart from looking at models which form the backbone of excitable models, our work allows us to speculate on the role that stochastic resonance, which can arise in this context, may play in the transmission of sensory information.

Acoustic Stimulation↗
PubMed1987

Effects of ECT on the TRH stimulation test.

The prognostic value of the TRH stimulation test was evaluated in 23 inpatients with major depressive disorder before and after a trial of ECT. In contrast to previous reports, the peak TSH response to TRH was significantly decreased after treatment compared with before treatment. This effect was consistent across individuals and subgroups (responders/nonresponders; unilateral/bilateral ECT). The particular ECT technique used in the study may account for the discrepancies between these findings and those previously reported by other authors.

Aged↗
PubMed1983

Efficacy of graded elastic compression in the lower leg.

Graded elastic compression stockings on the lower leg were evaluated for their ability to (1) decrease leg volume, (2) decrease circumference, and (3) alleviate discomfort. One hundred three test subjects participated in this study, including 30 normal, asymptomatic control subjects. The conditions of the 73 symptomatic patients were categorized by pain and swelling, varicose veins, venous stasis, lymphedema, and phlebitis, which constituted symptoms in 120 legs. Although total body weight did not change during the week of observation, the volume, circumference, and pain decreased in the symptomatic group. The volume of the stockinged leg decreased in comparison with the nonstockinged control leg in the asymptomatic subjects as well. We conclude that non-custom-made graded elastic stockings with 24 mm Hg of pressure at the ankle are effective in decreasing volume, circumference, and symptoms in the lower leg in patients with minimal problems during a one-week period.

Ankle↗
PubMed1983

Quantitative determination of haloperidol in human plasma by high-performance liquid chromatography.

We present a method for the quantitative determination of haloperidol in human plasma. The high-performance liquid chromatographic method of analysis is a significant advancement in terms of ease and speed of haloperidol determination. The drug and the internal standard, chlorohaloperidol, are extracted from 2.0 ml of serum or plasma, back-extracted into the aqueous mobile phase, separated on a C-18 reversed-phase column, and monitored at 254 nm. The potential interference by other drugs was evaluated and was found to be negative. The method is sensitive to at least 5 ng/ml of extracted material and is suitable for drug measurement in the therapeutic range (5-20 ng/ml) and in the toxic range (greater than 50 ng/ml).

Chromatography, High Pressure Liquid↗
PubMed1979

Suppressor cell function in atopic dermatitis associated with elevated immunoglobulin E.

Suppressor cell function was evaluated in 11 patients with atopic dermatitis (AD) and elevated IgE levels (mean, 4,554 IU/ml +/- 1,825 SEM) and compared to 11 matched nonatopic controls (135 IU/ml +/- 52 SEM). Two assays were employed to evaluate suppressor cell function. In the first assay, concanavalin A--activated suppressor cell activity of AD and control subjects were compared. In the second assay, peripheral blood mononuclear cells (PBM) from the same AD and control subjects were stimulated with varying doses of mitogen at day 0 and after 24 hr of preculture. In this system, increased proliferative response of precultured cells as compared to 0-hr cells has previously been shown in normals to represent loss of suppressor cell function in vitro. The lack of such an increase implies aberrant suppressor cell function. The data from both assays showed no significant difference in the degree of suppressor cell function of the patient population vs the control population. Thus, suppressor cell function as tested in these proliferative assays appears normal in AD patients with increased IgE.

Cells, Cultured↗
PubMed1976

Hepatic carbamyl phosphate synthetase and ornithine transcarbamylase in mouse influenze A and influenze B infection.

In mice infected with mouse-adapted influenza A/PR/8/34, hepatic carbamyl phosphate synthetase (CPS) activity was reduced to 88%, and ornithine transcarbamylase (OTC) was reduced to 83% of control values. In mice infected with mouse-adapted B/Lee/40, CPS activity was 98% was 94% of control values. These limited reductions in enzyme activity were attributed to a nonspecific debilitating effect of acute influenzal pneumonia. These findings suggest that the pronounced reduction of CPS and OTC activities reported in Reye's syndrome in man are not a general manifestation of the severity of influenza infection.

Adult↗
PubMed1972

Documentation of auxotrophic mutation in blue-green bacteria: characterization of a tryptophan auxotroph in Agmenellum quadruplicatum.

A tryptophan-requiring auxotroph of Agmenellum quadruplicatum strain BG1, a species of blue-green bacteria, was isolated by means of a nitrosoguanidine-penicillin procedure. Its growth characteristics were determined, and the enzymological block was identified in the A activity of tryptophan synthetase. Starvation of the auxotroph for tryptophan resulted in the derepression of the synthesis of all five enzymes. The first four enzymes derepressed 2- to 3-fold, and tryptophan synthetase B derepressed 20-fold. In the parental prototroph, BG1, anthranilate synthetase was active in crude extracts with ammonia as the amino donor reactant, but not with glutamine.

Anthranilate Synthase↗