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Biomedical subjects

T Thompson

Publications and source records attributed to T Thompson.

At least 145 records · Page 8Linked to original sources
PubMed1988

Therapeutic options in IgA nephropathy.

IgA nephropathy (IgAN) is a common form of glomerulonephritis that leads to end-stage renal disease at variable rates in 20% to 30% of cases. A rational approach to therapy requires an understanding of pathogenetic mechanisms that are largely unknown. Several therapeutic approaches have been used, generally in uncontrolled trials, aimed at lowering levels of circulating immune complexes, affecting cellular immunity, or removing antigens through dietary restriction. Thus far, no clear-cut beneficial effects are evident. Alternative means of changing glomerular hemodynamics through prevention of harmful mediators await exploration.

Antigen-Antibody Complex↗
PubMed1988

Effects of buprenorphine, methadone and naloxone on acquisition of behavioral chains.

Buprenorphine, methadone and naloxone were administered to pigeons key pecking under a repeated acquisition procedure. Under this procedure subjects are required to emit a new sequence of responses each session to receive access to food. All three drugs reduced overall key pecking rates although naloxone's rate-reducing effect was limited to the highest dose (30 mg/kg). The dose-effect curves for overall key pecking rate under buprenorphine and methadone were similar though the effective dose range for buprenorphine appeared wider. Methadone increased percentage of total errors at the highest doses, but neither buprenorphine nor naloxone affected total error levels very much. Within-session errors were increased early in the session under high methadone doses. Low buprenorphine doses also showed some tendency to increase errors early in the session. Buprenorphine and methadone reduced the number of chains completed in a dose-dependent manner. Buprenorphine was also administered daily at the most behaviorally disruptive dose (10 mg/kg/day). Under this dosing schedule, the behavior-suppressing effects of buprenorphine returned to base-line levels within 4 days. Error rates were unaffected by daily buprenorphine administration.

Animals↗
PubMed1987

Conditional relations by monkeys: Reflexivity, symmetry, and transitivity.

Two cynomolgous macaques categorized six colors into two groups of three after conditional discrimination training (zero-delay symbolic match-to-sample). The procedures resulted in the establishment of relations among the elements of each set-relations that were not specifically trained and that can be characterized by the properties of reflexivity, symmetry, and transitivity. Each set of colors was related to a characteristic pattern of responding: One response pattern involved temporal duration (press and hold the response keys); the second response pattern entailed repeated pressing and releasing of the response keys (fixed ratio 8). Six combinations of two colors were trained, three combinations from each set. After discriminative performance stabilized for each monkey, they were tested with 10 additional color combinations, all of which differed from the training combinations. The conditional relations established between test combinations can be characterized as stimulus equivalence. The training procedures were analogous to the procedure of using category names, and have implications for understanding the function of language in the formation of equivalence classes.

Journal Article↗
PubMed1987

An animal model of the interpersonal communication of interoceptive (private) states.

Pigeons were taught to interact communicatively (i.e., exchange discriminative stimuli) based on 1 pigeon's internal state, which varied as a function of cocaine, pentobarbital, and saline administration. These performances generalized to untrained pharmacological agents (d-amphetamine and chlordiazepoxide) and were observed in the absence of aversive stimulation, deprivation, and unconditioned reinforcement. The training procedure used in this study appears similar to that by which humans learn to report on (tact) their internal environments and may be construed as a rudimentary animal model of the interpersonal communication of private events.

Animal Communication↗
PubMed1987

Interaction of methadone, reinforcement history, and variable-interval performance.

In the present study, we examined how a reinforcement schedule history that generated high or low rates of responding influenced the effects of acute (Experiment 1) and chronic (Experiment 2) methadone administration. Initially, key-peck responses of pigeons were maintained under a variable-interval 90-s schedule of food presentation, and a methadone dose-response curve was determined with doses of 0.6, 1.2, and 2.4 mg/kg. The pigeons were then exposed, for at least 40 sessions, to either a fixed-ratio 50 schedule or a differential-reinforcement-of-low-rate 10-s schedule, or were given continued exposure to the variable-interval schedule. The methadone dose-response curve was redetermined after all pigeons again were responding under the variable-interval schedule. The effects of two different daily methadone doses (9.0 and 12.0 mg/kg/day) and withdrawal precipitated by naloxone also were assessed. Experience with a fixed-ratio or differential reinforcement of low rate schedule did not result in significantly different response rates under the variable-interval schedule and, in general, the acute effects of methadone did not have differential effects correlated with schedule history. However, for 2 of 4 subjects the rate-decreasing effects of methadone on rates of key pecking were greater following a history of low-rate responding, suggesting a possible interaction between schedule history and effects of methadone. Daily methadone administration under the variable-interval schedule revealed that pigeons with experience under the differential reinforcement of low rate schedule developed more rapid and complete tolerance to the rate-decreasing effects of methadone. Three of the 4 subjects in this group showed rate increases above drug-free baselines during chronic methadone dosing. Pigeons with a history of fixed-ratio responding also developed tolerance to the rate-decreasing effects of methadone but without the subsequent rate increases seen by subjects with low-rate histories. No subjects with variable-interval histories showed complete recovery of drug-free baselines, suggesting that interpolated training under other schedules may attenuate the rate-altering effects of chronically administered drugs. Naloxone (1.0 mg/kg), administered during the chronic methadone phase, resulted in greater disruption of responding by pigeons with a history of low-rate responding, as compared to subjects in the other two groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Splenic hemangioma with thrombocytopenia in a newborn.

The case report of a newborn infant with a splenic hemangioendothelioma with the life-threatening complications of thrombocytopenia, anemia, and disseminated intravascular coagulation is presented together with a review of the literature. Removal of the tumor via splenectomy, despite the known risk of subsequent overwhelming sepsis due to encapsulated organisms in the young child, is the treatment of choice for splenic hemangiomas complicated by thrombocytopenia. The use of enhanced CT with delayed filling is a diagnostic tool in the workup of suspected hemangiomatous lesions.

Anemia, Neonatal↗
PubMed1986

Asynchronies of diphenhydramine plasma-performance relationships.

The relation between performance on driving-related tasks and plasma levels of diphenhydramine was studied in eight male volunteers over 24 hours following oral administration. DPH plasma concentrations rose to peak levels in 1.5-2.5 hours varying with dose, declining to a nearly constant level by 12-24 hours. For all behavioral measures, the shape of performance curves over time was similar to that of plasma, reaching maximum decrements in 1-4 hours. The relation between plasma levels and performance was asynchronous varying with behavioral measure and dose. The use of plasma DPH values to predict performance decrements is limited due to the bivalued nature of these relationships in time. Nonetheless, it would appear that if DPH is administered in the therapeutic dosage range at the intervals typically recommended for cold symptoms and allergies, it appears some aspects of human performance may be impaired.

Administration, Oral↗
PubMed1986

Effects of imipramine on responding reduced by methadone.

Interactions between methadone and acute and chronic imipramine were studied in pigeons key pecking under a multiple variable interval 15-sec variable interval 150-sec schedule of food presentation. Both drugs decreased response rates at the highest doses. The VI 15-sec schedule was slightly more sensitive to acute drug administration than was the variable interval 150-sec schedule. Acute combinations of the two drugs neither ameliorated nor exacerbated the effects of either drug alone. Chronic imipramine alone had no lasting effect on responding. Unlike acute combinations, chronic imipramine lessened the rate reducing effect of methadone.

Animals↗
PubMed1986

Structural similarity between the lepidoptera- and diptera-specific insecticidal endotoxin genes of Bacillus thuringiensis subsp. "kurstaki" and "israelensis".

A gene from Bacillus thuringiensis subsp. "israelensis" was cloned from the large plasmids of this subspecies and was shown to code for a mosquitocidal polypeptide. The gene could be expressed in either Escherichia coli, Bacillus subtilis, or B. thuringiensis subsp. "israelensis" to produce the larvicidal activity. Similarly, a Lepidoptera-specific toxin gene from B. thuringiensis subsp. "kurstaki" was also cloned and expressed in E. coli and B. subtilis. Both cloned genes were sequenced and subjected to computer analysis. A long open translational reading frame coded for the B. thuringiensis subsp. "kurstaki" gene product. However, the B. thuringiensis subsp. "israelensis" clone was composed of two adjacent open reading frames oriented as if they were in a transcriptional operon. The products of the cloned genes retained their specificity for either Lepidoptera or Diptera. The control regions immediately preceding the toxin genes of both B. thuringiensis subspecies showed considerable DNA homology, most likely because both toxins are expressed only during sporulation. In addition, the deduced amino acid sequences from the two contiguous B. thuringiensis subsp. "israelensis" genes bore a striking resemblance to the deduced amino acid sequence from the single larger B. thuringiensis subsp. "kurstaki" gene, as if these two arrangements were evolutionarily related.

Amino Acid Sequence↗
PubMed1986

The effect of a low protein diet with amino acid/keto acid supplements on glucose metabolism in children with uremia.

Six children with chronic renal failure were treated with dietary protein restriction and essential amino acid and keto acid supplements for 6 months. Dietary protein and phosphate intake decreased, dietary calcium increased, and dietary carbohydrate and energy did not change. Plasma urea and urea to creatinine ratio decreased significantly during treatment. Glucose metabolism was studied before and after 6 months of treatment using the hyperglycemic clamp technique. Fasting hyperglycemia, glucose intolerance, and insulin resistance improved during treatment, while fasting insulin and insulin levels during hyperglycemia did not change. These metabolic changes were not related to hyperparathyroidism and were probably due to reduction in nitrogen toxicity.

Adolescent↗
PubMed1986

Units of analysis and kinetic structure of behavioral repertoires.

It is suggested that molar streams of behavior are constructed of various arrangements of three elementary constituents (elicited, evoked, and emitted response classes). An eight-cell taxonomy is elaborated as a framework for analyzing and synthesizing complex behavioral repertoires based on these functional units. It is proposed that the local force binding functional units into a smoothly articulated kinetic sequence arises from temporally arranged relative response probability relationships. Behavioral integration is thought to reflect the joint influence of the organism's hierarchy of relative response probabilities, fluctuating biological states, and the arrangement of environmental and behavioral events in time.

Journal Article↗