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L T Tsai

Publications and source records attributed to L T Tsai.

6 recordsLinked to original sources
PubMed2000

Dopamine modulates acute responses to cocaine, nicotine and ethanol in Drosophila.

BACKGROUND: Drugs of abuse have a common property in mammals, which is their ability to facilitate the release of the neurotransmitter and neuromodulator dopamine in specific brain regions involved in reward and motivation. This increase in synaptic dopamine levels is believed to act as a positive reinforcer and to mediate some of the acute responses to drugs. The mechanisms by which dopamine regulates acute drug responses and addiction remain unknown. RESULTS: We present evidence that dopamine plays a role in the responses of Drosophila to cocaine, nicotine or ethanol. We used a startle-induced negative geotaxis assay and a locomotor tracking system to measure the effect of psychostimulants on fly behavior. Using these assays, we show that acute responses to cocaine and nicotine are blunted by pharmacologically induced reductions in dopamine levels. Cocaine and nicotine showed a high degree of synergy in their effects, which is consistent with an action through convergent pathways. In addition, we found that dopamine is involved in the acute locomotor-activating effect, but not the sedating effect, of ethanol. CONCLUSIONS: We show that in Drosophila, as in mammals, dopaminergic pathways play a role in modulating specific behavioral responses to cocaine, nicotine or ethanol. We therefore suggest that Drosophila can be used as a genetically tractable model system in which to study the mechanisms underlying behavioral responses to multiple drugs of abuse.

Animals↗
PubMed1990

Enhanced recovery of cytomegalovirus in conventional tube cultures with a spin-amplified adsorption.

Low-speed centrifugation-mediated adsorption was evaluated as an enhancement of infectivity of clinical and laboratory strains of cytomegalovirus (CMV) occurring with cells grown in conventional culture tubes. The time required for reporting of primary isolates of CMV from urine specimens adsorbed onto monolayers of WI-38 cells in culture tubes was calculated. Of 668 specimens adsorbed by the stationary phase (SP) method, 98 were positive by cytopathic effect (CPE) that required an average of 16.8 days for recovery in culture. However, the appearance of CPE required a shorter average time of 11.9 days for 70 CMV strains isolated from 283 specimens adsorbed in tube cultures by the spin-amplified (SA) method. In another phase of clinical CMV recovery, urine specimens were adsorbed by the SA method onto cell cultures grown in both shell vials and test tubes. Of 594 specimens inoculated, a total of 74 were positive by either CPE in test tubes or immunostaining-localized early antigen in shell vials. Approximately one-third of these CMV isolates were recovered only by CPE from specimens adsorbed by the SA method in test-tube cultures. In a related study to further evaluate differences between adsorption methods, the AD-169 laboratory strain of CMV was adsorbed by SP and SA methods onto MRC-5 cells grown in both culture vessels. Early antigen detection by immunomicroscopy was found in the infected cells at least 2 to 4 days prior to the appearance of CPE, regardless of adsorption procedure. In both vessels, the replication of AD-169 virus in cultures adsorbed by the SA method consistently exceeded that of virus adsorbed by the SP procedure. CPE occurred 24 to 48 h earlier and progressed two to four times more extensively; early antigen was expressed two- to fourfold greater within 24 to 48 h postinfection; and foci of infected cells containing late antigen were two to four times greater in number at 1, 2, and 5 days postinfection. Overall, the replication and enhancement of infectivity of laboratory and clinical strains of CMV as determined by CPE and early and late antigen expression occurred most efficiently with specimens adsorbed by the SA method onto cultures grown in conventional tubes or shell vials.

Adsorption↗
PubMed1990

[Clinical studies of neonatal hyperbilirubinemia treated with blood exchange transfusion].

From April 1984 to November 1989, 194 cases of neonatal hyperbilirubinemia treated with blood exchange transfusions (BET) were studied. The patients included 127 male and 67 female neonates, with an age ranged from 13 hours to 16 days. The most common cause was idiopathic (52.6%), followed by G-6-PD deficiency (23.7%), and sepsis (12.9%). Most of the neonates received BET at the 4th day of birth (23.2%), but there were still 30 cases (15.5%) that received BET after 1 week of age. There were 17 cases (8.8%) with maximum serum bilirubin lower than 20 mg/dl before receiving BET, five of them were LBW infants; 11 cases (5.7%) were greater than 40 mg/dl. The mean of maximum serum bilirubin was 26.9 +/- 7.96 mg/dl. Most of the cases received BET once (145 cases) or twice (33 cases). There were two cases that received up to six BET's. One was G-6-PD deficiency and one idiopathic in etiology. No significant difference of BET frequency between sex or body weight (p greater than 0.05) was found. Newborns with higher serum bilirubin due to G-6-PD deficiency, received more BET (p less than 0.05). No significant differences of the pH value (7.33 +/- 0.08 vs 7.35 +/- 0.10) and bicarbonate values (21.20 +/- 3.99 vs 22.00 +/- 3.83 mM/L) occurred before and after blood exchange transfusion (p greater than 0.1). The serum calcium decreased significantly after BET (3.88 +/- 0.91 vs 3.15 +/- 6.97 mEq/L, p less than 0.05). There were 11 deaths in this series, the mortality rate was 5.7%. Three cases (1.5%) were dead within 6 hours after BET.(ABSTRACT TRUNCATED AT 250 WORDS)

Bilirubin↗