Humans' folk physics is sensitive to physical connection and contact between a tool and reward.

Three experiments examined adult humans' folk physics (i.e., their naturally occurring understanding of the physical world) using variations of rope-and-banana problems that are used to study chimpanzees' folk physics. When presented with symbolic versions of these problems, the participants' choices were controlled by both the presence of a physical connection between a tool and reward (unlike chimpanzees' choices) and the degree of contact between these objects (more like what controls chimpanzees' choices). Similar results were obtained when actual ropes and bananas were used. We speculate that the degree of contact between a tool and a reward influenced people's behavior because contact and physical connection are often correlated in people's natural environments and because contact is a reliable predictor of physical connection.

Incidence, prevalence and possible risk factors for pneumonitis in patients with rheumatoid arthritis receiving methotrexate.

OBJECTIVE: Methotrexate (MTX) is being used increasingly to treat rheumatoid arthritis (RA). Pneumonitis is a serious side effect of MTX therapy (P-MTX). Our aim was to determine in patients with RA the incidence and prevalence of P-MTX in Western Australia and identify risk factors for the development of this adverse reaction. METHODS: Patients with P-MTX were identified by (a) direct communication with rheumatologists in Western Australia, (b) use of a computerized clinical database, (c) questionnaire inquiry of all other rheumatologists in Australia. Possible risk factors for P-MTX were examined using age/sex matched case controls selected from the computerized clinical database. RESULTS: Ten definite and 3 probable cases of P-MTX were identified. Local incidence of P-MTX was 1/35.4 patient years MTX treatment; if definite and probable cases are included (1/49.6 patient years MTX treatment for definite cases alone). Twelve patients with P-MTX were compared with 24 age/sex matched controls. A shorter duration of MTX treatment and a higher incidence of preexisting lung disease were observed in P-MTX cases but these differences were not statistically significant. No difference was observed between the P-MTX and control patients with respect to rheumatoid factor, duration of RA, use of tobacco, dose of MTX, serum creatinine, creatinine clearance or concurrent treatment with aspirin, nonsteroidal antirheumatic drugs or prednisolone. CONCLUSION: Our results indicate that in hospital clinic patients with RA pneumonitis is a common adverse reaction. They suggest that hypersensitivity is probably responsible for most cases of pneumonitis associated with MTX, but preexisting lung disease may confer increased risk.

Intraarticular pressure and the relationship between synovial perfusion and metabolic demand.

We examined the influence of intraarticular pressure on products of synovial energy metabolism in patients with knee effusions. A range of intraarticular pressures was generated by controlled flexion. Pressures greater than or equal to 45 mm Hg were associated with increased synovial fluid lactate concentrations and pCO2, and decreased pH. Our results suggest that pressures greater than or equal to 45 mm Hg, which we also observed during standing and walking, can cause synovial ischemia and hypoxia manifest in a perfusion/metabolic demand mismatch. Monitoring changes in SF concentrations of uric acid did not provide consistent evidence for accelerated purine degradation following periods of inadequate perfusion. Overall, our results suggest that synovial blood flow can be compromised by modest elevations in intraarticular pressure in the range encountered during daily activity in patients with knee effusions.

Evaluation of direct and buffy coat films of peripheral blood for the early detection of bacteraemia.

During an 8 month period, 298 evaluations of direct and buffy coat films of peripheral blood for the detection of bacteraemia were undertaken in 287 infants (243 less than 24 h of age and 55 aged between 2 days and 30 days). Bacteraemia was diagnosed by simultaneously drawn aerobic and anaerobic blood cultures. Intracellular organisms were observed in both the direct and buffy coat films of only four of 24 infants with bacteraemia, giving a sensitivity of 17%, specificity of 100% and positive and negative predictive values of 100% and 93%, respectively. Of 12 infants with bacteraemia on the first day of life, eight were asymptomatic when studied, and none of the 12 had positive smears. As two of four infants with positive smears died, it is concluded that in fulminating sepsis the tests seem to correlate with the degree of illness and may give useful information as to the causative organism and the choice of antibiotic. However, as a screening test, the present methodology lacks sensitivity and cost-effectiveness.

Early diagnosis of neonatal sepsis using a hematologic scoring system.

Hematologic findings and published complete blood cell count criteria were evaluated as screening tests for neonatal sepsis. From the data obtained, a hematologic scoring system was formulated that assigns a score of 1 for each of seven findings: abnormal total leukocyte count, abnormal total neutrophil (PMN) count, elevated immature PMN count, elevated immature to total PMN ratio, immature to mature PMN ratio greater than or equal to 0.3, platelet count less than or equal to 150,000/mm3, and pronounced degenerative changes in PMNs. There were 298 evaluations for sepsis (243 in the first 24 hours of life and 55 between days 2 and 30). Twenty-six of 27 (96%) infants with sepsis and all 23 infants with probable infection had scores greater than or equal to 3, compared with 35 of 248 (14%) noninfected infants. The likelihood of sepsis with score greater than or equal to 3 was 31%, and this value differed with both gestational and postnatal ages (34% vs 8% in preterm and term infants less than 24 hours of age, and 65% thereafter). The higher the score the greater was the likelihood of sepsis. With score less than or equal to 2 the likelihood that sepsis was absent was 99%. The hematologic scoring system should improve the diagnostic accuracy of the complete blood cell count as a screening test for sepsis and could simplify and standardize the interpretation of this global test.