Positive and negative patterning in human causal learning.

Investigations of patterning discriminations by nonhuman animals have generally found that positive patterning is easier to learn than negative patterning. Studies of patterning discriminations in human causal learning tasks have failed to document any differences between positive and negative patterning. In the present study, human participants predicted an outcome on trials involving either a compound cue or its elements. Positive and negative patterning problems were successfully solved in a within-subjects design; negative patterning problems proved to be more difficult when an additional, 50% contingent cue was included (Experiment 2), but not when it was excluded (Experiment 1). Possible reasons for these results are discussed. The discussion concludes with an analysis of exemplar models (e.g., Pearce, 1994) of human causal learning and considers the conditions under which these models do and do not anticipate our results.

Evaluation of the potential of a polylactic acid barrier for correction of periodontal defects in baboons: a clinical and histologic study.

Created periodontal defects in baboons were treated with one of four possible treatment modes: (1) root preparation and Epi-Guide biodegradable polylactic acid barrier, (2) root preparation and Gore-Tex e-PTFE membrane, (3) root preparation only (no barrier), and (4) no root preparation and no barrier (control). Root preparation consisted of hand instrumentation and use of finishing burs. Measurements of gingival recession were recorded from color photographic slides taken weekly for 6 weeks following barrier placement. Block sections were removed from one animal 6 weeks after barrier placement and prepared for histologic evaluation. Significantly more gingival recession was observed at the Gore-Tex sites than at the Epi-Guide sites. There were no significant differences in gingival recession between the Epi-Guide sites and root preparation-only sites or control sites. Both types of barriers were histologically acceptable. At 6 weeks, the Epi-Guide material was present histologically in a partially resorbed state. There was a mild inflammatory reaction in the surrounding connective tissues.

Features of the nutrient database and analysis system for the Modification of Diet in Renal Disease Study.

This article describes the features of the nutrient database and analysis system developed for the Modification of Diet in Renal Disease (MDRD) Study and outlines the development process itself, an example of tailoring a database and analysis system for a complex, long-term clinical trial. The MDRD Study was a 15-center trial for men and women aged 18 to 70 years with chronic renal disease who were not on dialysis and who had not had a kidney transplant. The effects of three levels of protein and phosphorus intake and two levels of blood pressure management were assessed on the rate of decline in kidney function. This paper describes the development, structure, contents, and application of the nutrient database and analysis system that was used to enter, analyze, and report the MDRD Study dietary data.

Poor breath sounds with good voice sounds. A sign of bronchial stenosis.

The auscultatory finding of disparity in breath and voice sounds, the former being absent or faint whereas the latter are easily heard when compared to the corresponding site over the opposite lung, predicts stenosis of a main, intermediate, or lobar bronchus. Stenosis limits airflow and consequently reduces turbulence, causing diminution or absence of breath sounds over the poorly ventilated region; however, flow-independent voice sounds are not significantly impaired. This sign was present in ten patients, in each of whom bronchial stenosis was confirmed by bronchoscopy.

Warfarin-induced skin necrosis. A cutaneous sign of malignancy?

Patchy necrosis of the skin is a rare and unpredictable complication of oral anticoagulant therapy. Of the four patients that we have seen with this disorder, three had metastatic adenocarcinoma; in two, this was an unexpected finding. The association of a malignant neoplasm with warfarin-induced skin necrosis has not been emphasized previously. Whether such necrosis represents a clue to the presence of cancer or occurs only coincidentally in patients requiring anticoagulant therapy because of adenocarcinoma-associated thrombophlebitis must await further experience. A congenital or acquired deficiency of protein C may be the primary initiating factor.

Rifampin-containing chemotherapy for pulmonary tuberculosis associated with coal workers' pneumoconiosis.

The outcomes of 20 anthracite miners with coal workers' pneumoconiosis and culture-proved pulmonary tuberculosis treated with rifampin-containing chemotherapeutic regimens were determined by a retrospective review. Their mean age was 65 yr, and the duration of underground dust exposure averaged 27 yr. Nine miners had simple pneumoconiosis, 11 had progressive massive fibrosis, and 13 had cavitary disease; 3 also had extrapulmonary disease. All patients were given rifampin (mean, 12 months in survivors) plus one or more other effective agents; the mean duration of treatment with 2 or more drugs was 17 months. Follow-up averaged 46 months in those surviving more than 1 yr. Sputum cultures became negative and remained so within 3 months in 17 patients and within 5 months in the remainder. Eighteen patients survived more than 1 yr after completing chemotherapy. No clinical, radiologic, or bacteriologic relapses were observed during follow-up, but 5 patients died of nontuberculous causes. These results are superior to those reported previously in patients with coal workers' pneumoconiosis treated for pulmonary tuberculosis with regimens not containing rifampin. They suggest that treatment of tuberculosis in coal workers, even in the presence of progressive massive fibrosis and cavitary disease, can yield results as favorable as in nonpneumoconiotic patients provided the initial treatment regimen includes rifampin plus one or more other effective agents.

Intrapleural haemorrhage complicating pulmonary arteriovenous fistula.

Rupture of a pulmonary arteriovenous fistula caused intrapleural haemorrhage in a young woman with hereditary haemorrhagic telangiectasia and multiple bilateral fistulas. Bleeding was limited and exsanguination was probably prevented by pleural adhesions. Treatment included decortication, excision of the bleeding fistula, and prophylactic sclerosis of the opposite pleural space.

Sporadic Legionnaires' disease.

The first case of Legionnaires' disease recognized in Pennsylvania since the Philadelphia epidemic of 1976 was that of a 53-year-old emphysematous man who had extensive unilateral pneumonia accompanied by high fever, hypoxemia, and disorientation. His illness progressed despite treatment with cephalothin, but he recovered coincident with the administration of gentamicin and erythromycin. The diagnosis was established serologically by a 32-fold rise in antibody titer to the agent of Legionnaires' disease. Similar illness did not affect others in his community, and infection in four family members was excluded clinically and serologically.

Metabolic disposition of 2-phenylethylamine and the role of depression in methadone-dependent and detoxified patients.

We have now postulated that differences in the innate capacity of individuals to synthesize, store and utilize biogenic amines may provide the biological basis for human abuse of narcotic and other drugs, and that these drugs are used in an apparent unconscious effort to self-medicate against an inherent affective disorder. In this communication, we attempted a preliminary characterization of the narcotics withdrawal syndrome on biochemical and clinical parameters. Abstinence was found to be characterized by low urinary excretion of 2-phenylethylamine and depression. An indication for use of tricyclic drugs has been discussed.