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Biomedical subjects

T Thompson

Publications and source records attributed to T Thompson.

At least 127 records · Page 7Linked to original sources
PubMed1990

Effects on opioid-induced rate reductions by doxepin and bupropion.

Twelve pigeons key-pecked under a multiple variable interval 15-second, variable interval 150-second schedule of food reinforcement. Effects of two opioid drugs, buprenorphine and methadone, were determined alone and in combination with chronic daily administration of the antidepressants doxepin or bupropion. Methadone initially produced dose-dependent key-pecking rate reductions when administered acutely, prior to the session, while buprenorphine produced key-pecking rates that reached a plateau at 50-80% of baseline rate and were not reduced further by higher doses. Neither doxepin nor bupropion, given alone, had lasting effects on key-pecking rates. Chronic daily doxepin administration significantly attenuated methadone-induced response rate reductions. Bupropion reduced the effect of the highest methadone dose, but this effect was mitigated by the development of opioid tolerance. Unlike bupropion, doxepin interfered with the development of opioid tolerance. Neither antidepressant systematically altered effects of buprenorphine on key-pecking.

Animals↗
PubMed1990

Neuroleptics and learning: effects of haloperidol, molindone, mesoridazine and thioridazine on the behavior of pigeons under a repeated acquisition procedure.

The purpose of the present study was to examine the effects of haloperidol (0.3-10 mg/kg), molindone (0.3-5.6 mg/kg), mesoridazine (0.3-10) and thioridazine (0.3-25 mg/kg) on the behavior of pigeons exposed to a repeated acquisition procedure. At sufficiently high doses, each of these neuroleptics increased error rates (interfered with learning) and reduced rate of responding. When the drugs were compared on the basis of absolute doses administered, haloperidol disrupted behavior at doses considerably lower than the other drugs. If, however, chlorpromazine equivalent doses were examined, haloperidol was the least disruptive of the four drugs. Comparing the degree of behavioral disruption produced by the four drugs with their relative neuroreceptor affinities for dopamine D-2, cholinergic muscarinic, histamine H1, alpha-1 adrenergic and alpha-2 adrenergic receptors suggests that behavioral disruption cannot be attributed in any simple way to dopamine or acetylcholine receptor blockade. The relationship between the behavioral effects of neuroleptics and their simple neuropharmacological actions must be considered as highly tentative.

Animals↗
PubMed1990

Home-like architectural features of residential environments.

Adults who had no experience in the area of mental retardation viewed slides of residential settings, five providing housing for people with mental retardation, and rated their "home-likeness" (1 = home-like, 5 = institutional). Of 55 two-way comparisons, the mean home-likeness ratings of 48 such pairs differed significantly from one another. A .98 log-linear correlation was found between number of residents in a given facility and institutional ratings. Of 26 features of living rooms studied in detail, furniture position, lighting type, and lighting flexibility were highly correlated with home-likeness, whereas building code-specific features and seating type were minimally related to home-likeness.

Adult↗
PubMed1989

Treatment of pulmonary manifestations of gastroesophageal reflux in children two years of age or less.

Apnea and worsening bronchopulmonary dysplasia as well as recurrent aspiration pneumonia have been found to be consequences of gastroesophageal reflux in infants and young children. Antireflux procedures are effective in preventing gastroesophageal reflux; however, the effect of this operation on the course of these respiratory problems in very young patients is not known. We reviewed the results in 51 patients 2 years of age or less who underwent an antireflux fundoplication for pulmonary problems attributable to severe gastroesophageal reflux unresponsive to medical treatment. Twenty-eight patients had recurrent episodes of aspiration pneumonia, 14 had nonimproving or worsening bronchopulmonary dysplasia, and 9 had unexplained apneic episodes. Seventy-three percent of these patients had coexisting congenital anomalies or acquired problems. No operative deaths and no major surgical complications occurred. There were eight late deaths occurring between 1 and 25 months postoperatively: three were due to associated congenital anomalies or acquired problems, three to sepsis, and two to sudden infant death syndrome. Of the 43 surviving children, 91 percent with preoperative recurrent aspiration pneumonia had no additional episodes after Nissen procedure. Eighty-eight percent of the infants with unexplained apneic episodes showed marked benefit and 83 percent of those with bronchopulmonary dysplasia had clinical improvement. There were no late problems attributed to the operation even when it was performed in preterm infants. Therefore, we recommend fundoplication for patients 2 years of age or less who have a persistent pulmonary problem attributed to gastroesophageal reflux that does not respond to medical therapy.

Apnea↗
PubMed1989

Interaction of reinforcement history with methadone on responding maintained under a fixed-interval schedule.

Twelve pigeons were initially trained under either a fixed-ratio (FR) 50 or differential-reinforcement-of-low-rate (DRL) 10-sec schedule of food presentation. After 50 sessions of exposure to the foregoing schedules all pigeons key pecked under a fixed-interval (FI) 90-sec schedule. Key-peck rates differed as a function of schedule history, with FR-history subjects responding at significantly higher rates under the FI schedule than DRL-history subjects. To better compare methadone's rate-altering effects on baseline response rates, 8 naive pigeons were trained from the outset to key peck under an FI 90-sec schedule and were subsequently divided into 2 groups based on overall response rates (groups FI-H and FI-L). After at least 40 sessions under the FI schedule methadone dose-response curves were determined at doses of 0.6, 1.2 and 2.4 mg/kg. Low and intermediate methadone doses did not effect key-peck rates by pigeons with an FR history compared to significant rate decreases by pigeons having comparable rates but without a history of responding under an FR schedule (group FI-H). No differential effects following methadone were observed in low-rate subjects (DRL history and FI-L). When methadone (9.0 and 12.0 mg/kg/day) was administered chronically, response rates of all subjects were initially suppressed, with FI control subjects showing more complete recovery of drug-free baselines than either FR- or DRL-history groups. Naloxone (1.0 mg/kg) reversed methadone's rate-decreasing effects, although these actions were significantly less in subjects with prior experience under DRL schedules. Following completion of the chronic phase, and when subjects had been drug free for at least 14 sessions, the methadone dose-response curve was redetermined. The differential effects of methadone associated with reinforcement history were no longer evident, suggesting that a drug history can interact with a schedule history. These experiments add to the growing body of evidence indicating that prior experience can influence the behavioral actions of drugs independent of control rate of responding. Moreover, the data reveal that the influence of reinforcement schedule history depends on whether drugs are administered acutely or chronically.

Animals↗
PubMed1989

The ras and myc oncogenes cooperate in tumor induction in many tissues when introduced into midgestation mouse embryos by retroviral vectors.

Midgestation embryos were infected with replication-defective retroviral vectors that either transduced the myc oncogene, the ras oncogene, or both oncogenes simultaneously. The myc virus induced tumors in diverse organs at a very low frequency and with a long latency period, while approximately 20% of the mice derived from embryos infected with the ras virus developed tumors in the skin with a latency of 4-8 weeks. In contrast, infection of embryos with the ras/myc double oncogene virus resulted in 27% of the animals developing rapidly growing and malignant tumors in a great variety of tissues after a median latency period of 2-3 weeks. All tumors were of monoclonal origin, as shown by Southern analysis using the provirus as a molecular marker. Our results are consistent with the hypothesis that the ras and myc oncogenes cooperate in transforming cells, but that additional alterations are necessary for realization of the fully malignant phenotype. Our observations also suggest that a much wider range of cell types become targets for malignant transformation when the embryos are exposed to the myc and the ras oncogenes simultaneously than when exposed to the same oncogenes separately. Infection of mouse embryos with vectors carrying different oncogenes or oncogene combinations may be an efficient and rapid method for evaluating the spectrum of cell types at risk for malignant conversion following mutation of a protooncogene to a transforming gene.

Animals↗
PubMed1989

Effects of methadone on alternative fixed-ratio fixed-interval performance: latent influences on schedule-controlled responding.

Effects of methadone on pigeons' key pecking were examined under four conditions selected to analyze the control of behavior under alternative fixed-ratio fixed-interval schedules. In Condition 1, pigeons pecked under one of three different alternative schedules (alternative fixed-ratio 50 fixed-interval 90 s, alternative fixed-ratio 75 fixed-interval 90 s and alternative fixed-ratio 200 fixed-interval 90 s) each week. In Condition 2, fixed-ratio 50 or fixed-ratio 75 schedules were in effect during baseline sessions, and alternative fixed-ratio 50 fixed-interval 90-s or alternative fixed-ratio 75 fixed-interval 90-s schedules were in effect during sessions in which methadone was administered. In Condition 3, effects of methadone on key pecking maintained under fixed-ratio 50 and fixed-ratio 75 schedules were examined, whereas in Condition 4 the effects of methadone on key pecking under a fixed-interval 90-s schedule as well as fixed-ratio 50 and fixed-ratio 75 schedules were investigated. Control by the fixed-interval contingency was assessed by computing the proportion of total session reinforcers delivered under the fixed-interval schedule. Methadone administration (0.5-4.0 mg/kg) shifted the predominant source of schedule control under the alternative schedule from the fixed-ratio schedule to the fixed-interval contingency. This shift was dependent on methadone dose and fixed-ratio size. Control by the fixed-interval contingency was greatest following extensive exposure to the interval component embedded within the alternative schedule (Condition 1), but was apparent to a lesser degree with even very limited exposure to the alternative fixed-ratio fixed-interval schedule (Condition 2). Interreinforcement intervals comparable to those under fixed-interval schedule were not observed under the fixed-ratio schedules presented alone (Condition 3). Repeated exposure to the fixed-interval contingency outside the context of the alternative fixed-ratio fixed-interval schedule did not engender performance changes under a fixed-ratio schedule which would mimic those of increased fixed-interval contingency control (Condition 4). These data suggest that drug administration can be used to unmask the influence of contingencies that are latent under baseline conditions and reveal influences of both past and present environmental variables.

Animals↗
PubMed1988

Congenital adrenal hypoplasia and selective absence of pituitary luteinizing hormone: a new autosomal recessive syndrome.

Congenital hypoplasia of the adrenal glands (CHA) is a rare condition, particularly in the absence of a central nervous system (CNS) anomaly. Two major types of CHA have been described in the setting of an apparently normal CNS and pituitary: a cytomegalic type usually with X-linked recessive inheritance and a miniature adult type that, when hereditary, is an autosomal recessive trait. Glycerol kinase deficiency (GKD) is an X-linked recessive trait, and it may be associated with CHA and adrenal insufficiency, presumably because of deletion of adjacent X-linked loci. We report on three sibling infants, one male and two females, with normal CNS and lethal CHA of the miniature adult type, selective absence of pituitary LH; two of the infants also had glycerol kinase (GK) activity that was decreased but not in the GKD range. Restriction fragment length polymorphism (RFLP) analysis of X chromosome markers located at Xp21-p22 was carried out on the maternal grandfather, both parents, two of three affected infants, and a living normal brother. The results excluded the X-linked type of this disorder associated with GKD in this family. Autosomal recessive inheritance is most likely.

Adrenal Glands↗
PubMed1988

Multimodality treatment of non-small cell lung cancer: response to cisplatin, VP-16, and 5-FU chemotherapy and to surgery and radiation therapy.

Twenty-one patients with unresectable non-small cell lung cancer (NSCLC), 11 with stage III M0, five with malignant pleural effusion, and five with a single resectable metastasis were treated with multimodality therapy. All received two to three cycles of preoperative chemotherapy with a new sequential combination of cisplatin (50 mg/m2 IV X 1) followed by 5-FU infusion (40 mg/m2/hr X 72) and etoposide (80 mg/m2/day X 3). Thirteen of 21 (62%) had a partial response, and three (14%) had a minor response to chemotherapy. Of the 19 who underwent surgical exploration, 17 were confirmed to have NSCLC. Ten patients with NSCLC and one with choriocarcinoma were rendered disease free by resection of the primary tumor and lymph nodes. Six received intra- and/or perioperative interstitial therapy with 125I and/or 192Ir. Another patient was treated with 32P. Postoperative external radiotherapy was administered in 15 patients, and adjuvant chemotherapy was administered in ten. This multimodality therapy was well tolerated, safe, and highly effective, resulting in excellent palliation even in patients with pleural effusion and metastasis. The most promising results were in unresectable stage III M0 with a partial response rate of 82% following neoadjuvant chemotherapy and a complete response rate of 73% after surgery. In this group, median survival has not yet been reached and will exceed 12 months.

Adult↗
PubMed1988

Chromatin structure of hormone-responsive Moloney murine leukemia virus proviruses that contain sequences from mouse mammary tumor virus.

The chromatin structure of chimeric Moloney murine leukemia viruses (M-MuLVs) containing a glucocorticoid response element (GRE) from mouse mammary tumor virus (MMTV) inserted into the long terminal repeat (LTR) was investigated. Nuclear run-on assays indicated that transcription from the chimeric proviruses was induced 2- to 4-fold by dexamethasone. The wild-type M-MuLV 5' LTR contained a DNase I hypersensitive (HS) site at the TATA sequences, as well as four sites in the enhancer region. The chimeric LTRs contained these sites, as well as three additional sites in the MMTV sequences. Two of the MMTV sites were present in the absence of hormone, while one was hormone-induced. In addition, internal MMTV sequences appeared protected from DNase I digestion in the absence of hormone, suggesting bound protein. Hormone treatment resulted in loss of the DNase I protection.

Base Sequence↗
PubMed1988

Stereotypic behavior of mentally retarded adults adjunctive to a positive reinforcement schedule.

Stereotypic behavior is one of the more common disturbed behaviors displayed by people who are developmentally disabled. This study evaluated the indirect effects on stereotypic frequency when the value of a concurrent fixed-interval reinforcement schedule for adaptive behavior was varied. Three profoundly mentally retarded adults performed a simple adaptive task reinforced under a fixed-interval schedule. The reinforcement schedule value was varied from fixed-interval 15 to 90, and 180 seconds after schedule control under each condition was demonstrated. The dependent measure was the frequency of stereotypic behavior. Stereotypic behavior increased in direct relation to the interval length. The theoretical and practical implications of treating stereotypies as an adjunctive behavior partially controlled by the reinforcement frequency for adaptive behaviors are discussed.

Adult↗
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↗