Biomedical subjects
Publications and source records attributed to R L Thompson.
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The contingency between conditional and unconditional stimuli in classical conditioning paradigms, and between responses and consequences in instrumental conditioning paradigms, is analyzed. The results are represented in two- and three-dimensional spaces in which points correspond to procedures, or procedures and outcomes. Traditional statistical and psychological measures of association are applied to data in classical conditioning. Root mean square contingency, Ø, is proposed as a measure of contingency characterizing classical conditioning effects at asymptote. In instrumental training procedures, traditional measures of association are inappropriate, since one degree of freedom-response probability-is yielded to the subject. Further analysis of instrumental contingencies yields a surprising result. The well established "Matching Law" in free-operant concurrent schedules subsumes the "Probability Matching" finding of mathematical learning theory, and both are equivalent to zero contingency between responses and consequences.
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Weakly electric fish of the African family Mormyridae emit pulses at variable intervals with a distribution skewed toward longer intervals. Fourteen specimens of the genera Mormyrops, Gnathonemus, and Marcusenius were classically conditioned to increase briefly their discharge frequency. The unconditioned stimulus was electric shock and the conditioned stimulus was light. These results are novel in that the overt conditioned response involves neither secretion nor movement.
Infective complications are a significant problem in the management of patients with obstructive jaundice, despite the widespread use of prophylactic antibiotics. The cause of this may be suppression of the immune system. This study investigates the effect of serum from an animal model of extrahepatic biliary obstruction (BDL) for 7, 14, and 21 days on the lymphoproliferative response of a single population of T-lymphocytes to the mitogen phytohemagglutinin (PHA). Mean stimulation counts for lymphocytes cultured with 7 days with BDL serum (938 +/- 90 p = 0.04) and for 21 days with BDL serum (844 +/- 253 p = 0.04) are significantly lower than control serum (2382 +/- 1340). The effect of 14 days BDL serum has some suppression of lymphocyte stimulation but this is not significant (1115 +/- 429 p = 0.06). There was no significant correlation with any clinical parameters including bilirubin and the duration of jaundice. We have concluded that serum from animals with obstructive jaundice is immunosuppressive, but further studies are required to identify the factor and its role in vivo.
Surveillance activities for the detection of nosocomial infections at the University of Virginia Hospital (Charlottesville, Virginia) and at hospitals participating in the Virginia Statewide Infection Control Program have focused on outbreaks and device-related infections which are potentially preventable. Eleven outbreaks of nosocomial infections were identified at the University of Virginia Hospital between January 1, 1978 and December 31, 1982 (9.8 outbreaks/100,000 admissions). Ten of the 11 were centered in critical care units. The 269 patients involved in the epidemics represented 0.2% of all hospital admissions and 3.7% of all patients who developed nosocomial infections. Eight of the 11 outbreaks involved infection of the bloodstream, and the 90 patients who developed a bloodstream infection as part of an epidemic represented 8% of all patients with nosocomial bloodstream infections identified during the five-year study period. The reservoir of the 11 outbreaks involved devices (5), contaminated cocaine (1), probable blood products (1), other patients (3), and nursing personnel (1). Forty-one percent of all nosocomial bloodstream infections and 41% of all nosocomial pneumonias occurred in intensive care units (ICUs). In 38 hospitals in the state of Virginia with ICUs and practitioners who voluntarily reported surveillance data between June 1, 1980 and May 31, 1982, there were 264,757 patients admitted and a crude infection rate of 3%. Of note is that 1,867 of the 7,407 nosocomial infections (25%) occurred in the ICU patients. Several factors point to a compelling argument that the highest priority in infection control resources be assigned to the prevention and control of ICU infections: ICU patients often have serious device-related infections and may be identified as high risk prior to infection.(ABSTRACT TRUNCATED AT 250 WORDS)
In a retrospective study covering a period of 13 1/2 years, polymicrobial fungemia was documented in 22 (3.4%) of 645 patients with fungemia. These infections were hospital acquired and occurred in patients with significant underlying diseases. In terms of the clinical setting and features, predisposing factors, fungal species responsible, management, and mortality rate (59%), polymicrobial fungemia appears similar to the more common "monomicrobial" fungemia. With increasing numbers of patients at risk and improved laboratory detection of fungemia, clinicians will probably encounter increasing numbers of these polymicrobial bloodstream infections.
Eight patients with atypical pneumonia caused by the Legionnaires' disease organism were seen during the spring and summer of 1977. Two died of the acute illness. All patients were febrile and presented with symptoms of acute respiratory infection. Other symptoms included malaise, anorexia, chills, myalgia, and headache. Severe hypoxemia was a striking feature. Conventional methods to determine the etiology of these pneumonias were unsuccessful but subsequent serological studies confirmed the diagnosis of Legionnaires' disease. Seven patients were treated with beta-lactam antibiotics alone or with an aminoglycoside and all failed to respond. Six were subsequently treated with erythromycin and five who received this drug for at least 48 hours were markedly improved within this time period. We believe that erythromycin is effective in the treatment of Legionnaires' disease.
Septicemia is the major cause of morbidity in home parenteral nutrition patients, accounting for approximately 70% of rehospitalizations. To identify risk factors, the incidence of infection was examined in 41 current home parenteral nutrition patients, 30 with short-bowel syndrome (including 16 with inflammatory bowel disease and 11 with bowel infarction) and 11 with chronic obstructive disorders. Management, which was followed for a mean duration of 78.6 months (range, 1 to 15 1/2 years), was standardized by protocol. Ten patients never experienced infection during the average follow-up of 61 months (range, 14 to 174 months), whereas seven patients experienced frequent infections during the mean follow-up of 77 months (range, 24 to 180 months). Significant distinguishing features in the frequent-infection group were younger age (45 +/- 12 vs 66.9 +/- 14.3 years, p < .05), Crohn's disease (in five of seven vs zero of 10 subjects, p < .05), jejunostomies (in seven of seven vs one of 10 subjects, p < .0005), and central vein thrombosis (in five of seven vs zero of 10 subjects, p < .05). A greater proportion of the frequent-infection group had poor catheter-care technique and more were smokers. One hundred fifty septicemias were confirmed by blood culture, giving an average infection rate of one every 31 months, 52% caused by Gram-positive organisms (chiefly coagulase-negative staphylococci and Staphylococcus aureus), 30% caused by Gram-negative organisms, and 16% caused by fungus (chiefly Candida albicans).(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVE: To assess the efficacy of using an iodized talc slurry as a sclerosing agent instilled into the pleural space via a 12-French pigtail catheter for controlling malignant pleural effusions. DESIGN: A prospective study in which patients were followed until their death. SETTING: A university-affiliated tertiary-care teaching hospital. PATIENTS: Medical oncology patients admitted with symptomatic malignant pleural effusions were considered for iodized talc pleurodesis. MAIN OUTCOME MEASURES: The control of pleural effusion. Treatment failure was defined as any reaccumulation of fluid in the pleural space. RESULTS: Fifteen patients were treated for a total of 17 instillations. The median follow-up on all patients until death was 6 months (range 1-20). The most frequent adverse effect in the study group was pleuritic chest pain (60%). The probability of control of effusion, as determined by the method of Kaplan-Meier, was 81% (SEM 9.7%). The cost of preparing 5 g of iodized talc was $4.32 (US). CONCLUSIONS: Iodized talc slurry instilled through a small-bore pigtail catheter is a safe, economical, and effective treatment for malignant pleural effusion.
Over an 18-month period (January 1987 to June 1988), Group Health Cooperative (GHC) examined the direct medical costs and service utilization of enrollees with Class IV HIV conditions. Data is presented on inpatient stays, outpatient visits by specialty, and outpatient pharmacy, laboratory, home health, and purchased-outside services. Results for enrollees with Class IV HIV disease are compared to those for a control sample of enrollees, age and sex matched with the HIV sample. The per member per month (PMPM) cost for the HIV sample was $1,761, approximately 33 times greater than the PMPM cost for the control sample. Group Health's annualized cost of $21,130 per case and diagnosis-to-death cost of $31,700-$42,300 per case are comparable to costs of Class IV care in other settings. Primary care costs were 11 times that of controls. Several specialty areas (e.g., infectious disease, pulmonary, oncology, and radiation therapy) were impacted to a greater extent.