Theory of Mind and Social Informant Discrepancy in Autism

When autistic youth are asked to assess their own social skills, they frequently rate themselves more favorably than their parents rate them. The magnitude of this informant discrepancy has been shown to relate to key clinical outcomes such as treatment response. It has been proposed that this discrepancy arises from difficulties with Theory of Mind. Participants were 167 youth 11 to 17 years old; 72% male, and their parents. Youth completed self-report measures of social skills and social cognitive tasks, while their parents completed questionnaires regarding social skills. A repeated-measures ANOVA indicated both non-autistic and autistic youth rated themselves more favorably than their parents rated them across all measures. Zero-order correlations revealed that raw differences between parent- and participant-report were negatively correlated with scores on parent-reported Theory of Mind measures. However, polynomial analysis did not indicate interaction effects between parent- and participant-report on any of the measures used. Polynomial regression revealed that increases in parent-reported social skill predicted larger increases in parent-report Theory of Mind at low levels of parent-reported social skill compared to high levels of parent-reported social skill. Participant-report social skills predicted performance on a behavioral Theory of Mind test in a curvilinear fashion, such that the relationship was positive at low levels of participant-reported social skills, but negative at high levels. This study replicates the finding that raw difference score analyses may result in illusory effects that are not supported when using more contemporary analysis methods, and that more complex and subtle relationships between social insight and perspective-taking exist within autistic youth.

More than a pump: the endocrine functions of the heart

The endocrine functions of all tissues, including the heart, are being delineated in more detail as our understanding of cellular biology unfolds. Natriuretic peptides form an important counterregulatory system to balance the effects of sympathetic neurohormones. As we learn to intervene with therapeutic manipulations of this system, critical care practitioners will be involved in the assessment, monitoring, and evaluation of new cardiovascular therapies.

More than a pump: the endocrine functions of the heart

The endocrine functions of all tissues, including the heart, are being delineated in more detail as our understanding of cellular biology unfolds. Natriuretic peptides form an important counterregulatory system to balance the effects of sympathetic neurohormones. As we learn to intervene with therapeutic manipulations of this system, critical care practitioners will be involved in the assessment, monitoring, and evaluation of new cardiovascular therapies.

A physiological model for tert-amyl methyl ether and tert-amyl alcohol: hypothesis testing of model structures

The oxygenate tert-amyl methyl ether (TAME) is a gasoline fuel additive used to reduce carbon monoxide in automobile emissions. To evaluate the relative health risk of TAME as a gasoline additive, information is needed on its pharmacokinetics and toxicity. The objective of this study was to use a physiologically-based pharmacokinetic (PBPK) model to describe the disposition of TAME and its major metabolite, tert-amyl alcohol (TAA), in male Fischer-344 rats. The model compartments for TAME and TAA were flow-limited. The TAME physiological model had 6 compartments: lung, liver, rapidly perfused tissues, slowly perfused tissues, fat, and kidney. The TAA model had 3 compartments: lung, liver, and total-body water. The 2 models were linked through metabolism of TAME to TAA in the liver. Model simulations were compared with data on blood concentrations of TAME and TAA taken from male Fischer-344 rats during and after a 6-hour inhalation exposure to 2500, 500, or 100 ppm TAME. The PBPK model predicted TAME pharmacokinetics when 2 saturable pathways for TAME oxidation were included. The TAA model, which included pathways for oxidation and glucuronide conjugation of TAA, underpredicted the experimental data collected at later times postexposure. To account for biological processes occurring during this time, three hypotheses were developed: nonspecific binding of TAA, diffusion-limited transport of TAA, and enterohepatic circulation of TAA glucuronide. These hypotheses were tested using three different model structures. Visual inspection and statistical evaluation involving maximum likelihood techniques indicated that the model incorporating nonspecific binding of TAA provided the best fit to the data. A correct model structure, based upon experimental data, statistical analyses, and biological interpretation, will allow a more accurate extrapolation to humans and, consequently, a greater understanding of human risk from exposure to TAME.

Rapid identification of respiratory viruses: impact on isolation practices and transmission among immunocompromised pediatric patients

OBJECTIVE

To determine whether empiric isolation of patients with acute respiratory virus infection symptoms could be discontinued when preliminary shell vial cultures were negative, and the impact of this approach on hospital resources.

DESIGN

In 1993, we retrospectively reviewed respiratory virus test results from 1992 to 1993 and extended data collection prospectively through the 1993 to 1994 season. The rapid test and 48-hour shell vial results were compared to a standard of rapid test plus 5-day shell vial culture results to determine the sensitivity and specificity of these "preliminary" results.

SETTING

A 400-bed tertiary referral research hospital.

PATIENTS

Patients from any inpatient unit or clinic with acute respiratory virus infection symptoms who had a specimen submitted for respiratory virus culture. Patients were placed on empiric respiratory isolation pending culture results.

RESULTS

The overall sensitivity of the combined rapid and 48-hour culture results in adults and children was 97%. All 15 pediatric patients with respiratory syncytial virus infection who had specimens submitted on first suspicion of respiratory virus infection were positive by rapid test. Culture results were positive within 48 hours for 100% of patients with influenza A (15 patients), influenza B (6), and parainfluenza (18) viruses. Of 59 pediatric inpatients who were isolated empirically awaiting 5-day culture results, 31 (52%) ultimately were determined to be culture negative.

CONCLUSIONS

Empiric isolation of symptomatic children can be discontinued at 48 hours when both the rapid test and the early culture results are negative. Our institution would have saved 93 days of unnecessary isolation over 2 years had such a policy been in place.

Normotensive blacks have heightened sympathetic response to cold pressor test

The purpose of this study was to compare sympathetic nerve activity responses to the cold pressor test in black and white normotensive subjects. We recorded muscle sympathetic nerve activity (microneurography of the peroneal nerve), arterial blood pressure, and heart rate in 9 normotensive American blacks (24 +/- 2 years, mean +/- SEM) and 10 normotensive American whites (28 +/- 2 years) at rest and during hand immersion in ice water (cold pressor test). Body weight was not different in the two groups (72.4 +/- 3.7 versus 74.1 +/- 3.8 kg, black versus white subjects). During supine rest, mean arterial pressure (92 +/- 2 versus 93 +/- 3 mm Hg, black versus white), heart rate (66 +/- 4 versus 62 +/- 3 beats per minute, black versus white), and muscle sympathetic nerve burst frequency (12 +/- 2 versus 17 +/- 3 bursts per minute, black versus white) were not different in the two groups. During the cold pressor test, mean arterial pressure, heart rate, and muscle sympathetic nerve activity increased from supine rest in both groups. The magnitudes of increases in mean arterial pressure and total minute muscle sympathetic nerve activity were significantly greater in blacks than whites (33.5 +/- 3 versus 22.4 +/- 3 mm Hg and 416 +/- 24% versus 243 +/- 31% of control, respectively, black versus white, P < .05). The increases in heart rate were most significantly different for the two groups. These data suggest that the enhanced pressor response to cold stress observed in normotensive blacks is attributable to greater increases in peripheral sympathetic nerve activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastrointestinal complications in shock

The gut organs are vulnerable to injury during shock because of ischemia and reperfusion of the microcirculation. These injuries result in upper GI hemorrhage, liver dysfunction, and pancreatic and mesenteric necrosis. Toxic mediators, released via lymph drainage and with reperfusion, contribute to the failure of other organs and the development of refractory shock. Until single organ perfusion can be measured, the primary goal of care is to maintain systemic perfusion. Secondary goals are to decrease hydrogen ion accumulation, minimize pancreatic stimulation, remove hepatotoxic agents, and reduce blood bacteria. Gut ischemia is simply one piece of the puzzle in the multiple organ response to reduced systemic oxygenation and perfusion that characterizes the clinical syndrome of shock.