The relationship between ultrasound microcalcifications and psammoma bodies in thyroid tumours: a single-institution retrospective study

AIM

To investigate the diagnostic accuracy of ultrasound microcalcifications for the detection of malignancy in thyroid nodules and determine the validity of the concept that ultrasound microcalcification reflects the presence of psammoma body calcification in thyroid nodules.

MATERIALS AND METHODS

The laboratory information system at University Hospital Galway, a tertiary referral hospital, was used to compile a list of patients who underwent thyroid lobectomy or complete thyroidectomy over a continuous 12-month period with both preoperative ultrasound and postoperative histology available (n=106) from January to December 2019. The haematoxylin and eosin-stained histology slides of each case were sourced and reviewed under light microscopy by a histopathologist to determine the presence of psammoma body calcification within both benign and malignant thyroid nodules. Two radiologists reviewed preoperative thyroid ultrasound images of each case independently and blindly, and reported on the presence of ultrasonographic microcalcification.

RESULTS

There was a strong and significant relationship between the presence of preoperative ultrasound microcalcification and thyroid malignancy (p<0.001). Ultrasound microcalcification had a high specificity (93%) and positive predictive value (75%) for thyroid malignancy, with a diagnostic accuracy of 76%. Negative predictive value was high at 76.7%, while sensitivity was low at 42.8%. There was a strong and significant association between the presence of preoperative ultrasound microcalcification in thyroid nodules and the presence of pathological psammoma bodies on histology (p<0.001).

DISCUSSION

Ultrasound microcalcification has a strong and significant association with malignancy in thyroid nodules. This study supported the theory that ultrasound microcalcification occurs secondary to the presence of psammoma bodies within thyroid nodules.

The preferences of young adults with Type 1 diabetes at clinics using a discrete choice experiment approach: the D1 Now Study

AIM

Attending routine outpatient clinic appointments is a central self-management behaviour of individuals living with Type 1 diabetes. A large number of young adults with Type 1 diabetes disengage from diabetes services, which may contribute to poor psychosocial and diabetes outcomes. The aim of this study is to elicit preferences from young adults with Type 1 diabetes regarding clinic-related services to inform service delivery.

METHODS

A discrete choice experiment was developed to understand the preferences of young adults with Type 1 diabetes for clinic-related services.

RESULTS

Young adults recruited from young adult Type 1 diabetes clinics in 2016 completed the experiment (n = 105). Young adults with Type 1 diabetes showed a preference for shorter waiting times, seeing a nurse and a consultant, relative to a nurse alone, and a flexible booking system compared with fixed appointment times. Results suggest no preference for a nurse and a doctor, relative to a nurse alone, or other optional services (e.g. seeing dietitians or psychologists), type of HbA_1c test and digital blood glucose diaries over paper-based diaries.

CONCLUSION

This study highlights aspects of routine clinic appointments that are valued by young adults living with Type 1 diabetes, namely shorter waiting times at clinic, the option to see both a nurse and consultant at each visit and a flexible clinic appointment booking system. These findings suggest young adults with Type 1 diabetes value convenience and should help services to restructure their clinics to be more responsive to the needs of young adults.

Strength in Numbers: an international consensus conference to develop a novel approach to care delivery for young adults with type 1 diabetes, the D1 Now Study

PLAIN ENGLISH SUMMARY

Many young adults with type 1 diabetes struggle with the day-to-day management of their condition. They often find it difficult to find the time to attend their clinic appointments and to meet with their diabetes healthcare team. Young adults living with type 1 diabetes are not routinely involved in research that may help improve health services other than being invited to take part in studies as research participants. A 3-day international conference was held in Galway in June 2016 called "Strength In Numbers: Teaming up to improve the health of young adults with type 1 diabetes". It aimed to bring together people from a broad variety of backgrounds with an interest in young adults with type 1 diabetes. Young people with type 1 diabetes came together with healthcare professionals, researchers, software developers and policy makers to come up with and agree on a new approach for engaging young adults with type 1 diabetes with their health services and to improve how they manage their diabetes.The people involved in the conference aimed to reach agreement (consensus) on a fixed set of outcome measures called a core outcome set (COS) that the group would recommend future studies involving young adults with type 1 diabetes to use, to suggest a new approach (intervention) for providing health services to young adults with type 1 diabetes, and to come up with health technology ideas that could help deliver the new intervention. Over the 3 days, this diverse international group of people that included young adults living with type 1 diabetes, agreed on a COS, 3 key parts of a new intervention and 1 possible health technology idea that could help with how the overall intervention could be delivered.Involving young adults living with type 1 diabetes in a 3-day conference along with other key groups is an effective method for coming up with a new approach to improve health services for young adults with type 1 diabetes and better support their self-management.

ABSTRACT

Background A 3-day international consensus meeting was hosted by the D1 Now study team in Galway on June 22-24, 2016 called "Strength In Numbers: Teaming up to improve the health of young adults with type 1 diabetes". The aim of the meeting was to bring together young adults with type 1 diabetes, healthcare providers, policy makers and researchers to reach a consensus on strategies to improve engagement, self-management and ultimately outcomes for young adults living with type 1 diabetes. Methods This diverse stakeholder group participated in the meeting to reach consensus on (i) a core outcome set (COS) to be used in future intervention studies involving young adults with type 1 diabetes, (ii) new strategies for delivering health services to young adults and (iii) potential digital health solutions that could be incorporated into a future intervention. Results A COS of 8 outcomes and 3 key intervention components that aim to improve engagement between young adults with type 1 diabetes and service providers were identified. A digital health solution that could potentially compliment the intervention components was proposed. Conclusion The outputs from the 3-day consensus conference, that held patient and public involvement at its core, will help the research team further develop and test the D1 Now intervention for young adults with type 1 diabetes in a pilot and feasibility study and ultimately in a definitive trial. The conference represents a good example of knowledge exchange among different stakeholders for health research and service improvement.

Explaining Disparities in Ovarian Cancer Incidence Rates between Women of African and European Ancestry: The Role of Genetic Factors

Non-Hispanic White (NHW) women are at higher risk of ovarian cancer than African-American (AA) women. Approximately 30% of the difference in age-adjusted invasive epithelial ovarian cancer incidence rates (AAIR) between the two groups can be explained by differing oophorectomy rates and the prevalence of non-genetic risk and protective factors. Our purpose was to determine how much of the remaining difference in AAIRs could be explained by varying allele frequencies between NHWs and AAs for 18 genome-wide significant common susceptibility variants for ovarian cancer. Using data on 13,385 cases and 24,875 controls from the Ovarian Cancer Association Consortium, a genetic risk score (GRS) was created from 18 single nucleotide polymorphisms (SNPs) associated with ovarian cancer risk following the Collaborative Oncological Gene-environment Study (COGS) effort. Relative risks for each GRS quintile were estimated using conditional logistic regression, adjusting for genetic ancestry and conditioning on study site, age, and race. The population attributable risk percent (PAR) for GRS above the lowest quintile was calculated using the Bruzzi method. Previously reported oophorectomy and non-genetic risk factor (talc, oral contraceptive use, family history of ovarian cancer, endometriosis, parity and tubal ligation) adjusted incidence rates for ovarian cancer in NHWs and AA's were 7.2 and 5.8 per 100,000 respectively. These incidence rates were further adjusted for the contribution of the GRS from this analysis. The subsequent genetic PAR adjusted rate was 5.1 per 100,000 for the European ancestry group and 4.9 for the African ancestry group, after taking into account the different oophorectomy rates and prevalence of non-genetic risk factors. These incidence rates show the unexplained difference in incidence rates between NHWs and AAs is only 3.9%. Future efforts should focus on incorporating novel non-genetic and genetic factors into this analysis to determine whether essentially all of the difference in incidence between these groups can be explained.

Cesarean delivery is not associated with decreased at-birth fracture rates in osteogenesis imperfecta

Purpose

Osteogenesis imperfecta (OI) predisposes to recurrent fractures. The moderate-to-severe forms of OI present with antenatal fractures and the mode of delivery that would be safest for the fetus is not known.

Methods

We conducted systematic analyses on the largest cohort of individuals (n=540) with OI enrolled to-date in the OI Linked Clinical Research Centers. Self-reported at-birth fracture rates were compared in individuals with OI types I, III, and IV. Multivariate analyses utilizing backward-elimination logistic regression model building were performed to assess the effect of multiple covariates including method of delivery on fracture-related outcomes.

Results

When accounting for other covariates, at-birth fracture rates did not differ based on whether delivery was by vaginal route or by cesarean section (CS). Increased birth weight conferred higher risk for fractures irrespective of the delivery method. In utero fracture, maternal history of OI, and breech presentation were strong predictors for choosing CS for delivery.

Conclusion

Our study, the largest to analyze the effect of various factors on at-birth fracture rates in OI shows that delivery by CS is not associated with decreased fracture rate. With the limitation that the fracture data were self-reported in this cohort, these results suggest that CS should be performed only for other maternal or fetal indications, but not for the sole purpose of fracture prevention in OI.

Human adipose microRNA-221 is upregulated in obesity and affects fat metabolism downstream of leptin and TNF-α

AIMS/HYPOTHESIS

MicroRNAs (miRNAs) are short endogenous RNAs that regulate multiple biological processes including adipogenesis and fat metabolism. We sought to identify miRNAs that correlate with BMI and to elucidate their upstream regulation and downstream targets.

METHODS

Microarray-based expression profiling of 233 miRNAs was performed on subcutaneous abdominal adipose tissue biopsies from 29 non-diabetic Pima Indian participants. Correlation of the expression levels of eight miRNAs with BMI was assessed by quantitative reverse transcription (QRT) PCR in adipose samples from 80 non-diabetic Pima Indians with a BMI of 21.6-54.0 kg/m(2). The upstream regulation of one of these miRNAs, miR-221, was tested by treating cultured human pre-adipocytes with leptin, TNF-α and insulin. Predicted targets of miR-221 were validated using QRT-PCR, immunoblots and luciferase assays. The downstream effects of miR-221 overexpression were assayed by proteomic analysis.

RESULTS

Expression levels of miR-221 were positively correlated with BMI (particularly in women) and fasting insulin concentrations, while the levels of miR-193a-3p and miR-193b-5p were negatively correlated with BMI; other miRNAs did not show significant associations in the 80 samples. miR-221 was downregulated by leptin and TNF-α treatment in cultured human pre-adipocytes. Conversely, miR-221 overexpression upregulated several proteins involved in fat metabolism, mimicking peroxisome proliferator-activated receptor (PPAR) activation. Furthermore, miR-221 directly downregulated the adiponectin receptor 1 (ADIPOR1) and the transcription factor v-ets erythroblastosis virus E26 oncogene homolog 1 (ETS1). Adiponectin signalling is known to promote insulin sensitivity, and ETS1 is crucial for angiogenesis.

CONCLUSIONS/INTERPRETATION

Our data suggest that miR-221 may contribute to the development of the insulin resistance that typically accompanies obesity, by affecting PPAR signalling pathways and by directly downregulating ADIPOR1 and ETS1.

Ilizarov wire tensioning and holding methods: a biomechanical study

AIM

To investigate and compare two specific methods of Ilizarov wire tensioning and hold.

METHOD

This study utilised the vertical Hounsfield test machine H25KS, a stress/strain device with a load-cell linked to a computer program. Firstly, the department's present mechanical tensioners were assessed. Secondly, the method of twisting the three designs of wire holding bolts to achieve wire tension, as described by Ilizarov, was assessed. These bolts are described as "cannulated", "slotted" and "Russian" (which are hexagonal headed with a slot down one side).

RESULTS

The mechanical tensioners were found to be accurate, if inefficient, with a maximum producible tension of 1330N. The most effective bolts for creation of tension were the Russian, which produced mean wire tensions of 785N at 45 degrees; 1200N at 90 degrees; 1695N at 135 degrees. The cannulated and slotted bolts regularly broke the wires at 90 degrees twist.

CONCLUSION

The findings demonstrated two effective methods. The present tensioners were found to be inefficient when compared to the simple twisting of the wire holding bolts, which created equivalent tensions with ease and are capable of producing greater wire tensions. The Russian bolts are recommended for use when wire tension is created by bolt twisting.

Sequence variation in the gene encoding the 10-kDa prolamin in Oryza (Poaceae). I. Phylogenetic Implications

Oryza L. (Poaceae) contains approximately 20 wild and two domesticated species and nine genomes. Major disagreements exist on its systematics and genome evolution. Sequence polymorphism in the gene that encodes the 10-kDa prolamin polypeptide (a seed storage protein) was used to determine phylogenetic relationships and evaluate current systematics for 19 Oryza species. This gene in Oryza is approximately 402-bp long, and includes a 72-bp signal peptide region. A strict consensus tree shows Oryza brachyantha (FF) as the most basal species, followed by a polytomy of three clades that can be delineated based on genome composition: (1) the GG clade: Oryza granulata and Oryza meyeriana, (2) the EE clade: Oryza australiensis, and (3) the ABCD clade: the remaining Oryza species. Two subclades within the ABCD clade emerge, one containing species with the AA genome, the other with components of the BC and D genomes. Members of the AA subclade form a polytomy and were delineated by a single 3-base deletion. The African species Oryza punctata (BB) and the South American-endemic CCDD genome species form a strong lineage, pointing to a close genetic affinity of O. punctata to the missing DD genome donor. The strong association between the CC and BBCC species implies convergence at the gene level. The study supports the following sectional units of Oryza: Section Oryza (Series sativae and officinaliae), Section australiensis, Section Granulata, Section Brachyantha.

Cooperative action of ADMP- and BMP-mediated pathways in regulating cell fates in the zebrafish gastrula

It was shown in Xenopus and chick that Spemann's organizer activity is regulated through the negative action of Anti-Dorsalizing Morphogenetic Protein (ADMP). We report the characterization and functional properties of admp in zebrafish. admp expression profile is consistent with a role in the organizer, including the tail organizer. We studied admp function through overexpression experiments, with the use of a dominant-negative form (TR-ADMP) and of an antisense morpholino-modified oligonucleotide. Our results indicate that the ADMP pathway causes the restriction of anterior and axial fates and that ADMP, BMP2b, and BMP7 pathways have distinct actions but cooperate in establishing proper dorso-ventral regionalization. This is shown by partial rescue of the dorsalized mutant snailhouse and of the ventralized mutant chordino, upon admp and tr-admp RNA injection, respectively. Moreover, ADMP and BMP7 probably form heterodimers as shown by the ability of TR-ADMP and BMP7 to antagonize each other. We observed that a MYC-tagged ADMP was secreted and detected in the extracellular space, suggesting that admp could act at a distance. Simultaneous local inhibition of bmp function at the blastoderm margin and impairment of ADMP secretion led to the induction of secondary head structures, confirming that the two pathways cooperatively regulate organizer formation and activity.

Potential influence of acute CT on inpatient costs in patients with ischemic stroke

RATIONALE AND OBJECTIVES

Patients presenting with ischemic brain symptoms have widely variable outcomes dependent to some degree on the pathologic basis of their stroke syndrome. The purpose of this study was to determine the cost implications of the emergency use of a computed tomographic (CT) protocol comprising unenhanced CT, head and neck CT angiography, and whole-brain CT perfusion.

MATERIALS AND METHODS

By using a retrospective patient database from a tertiary care facility and publicly available cost data, the authors derived the potential savings from the use of CT angiography. CT perfusion, or both at hospital arrival by means of a cost model. The cost of the CT angiography-CT perfusion protocol was determined from Medicare reimbursement rates and compared with that of traditional imaging protocols. Cost savings were estimated as a decrease in the length of stay for most stroke patients, whereas the most benign (lacunar) strokes were assumed to be managed in a non-acute setting. Misdiagnosis cost (erroneously not admitting a patient with nonlacunar stroke) was calculated as the cost of a severe complication. Sensitivity testing included varying the percentage of misdiagnosed patients and admitting patients with lacunar stroke.

RESULTS

The nationwide net savings that would result from the adoption of the CT angiography-CT perfusion protocol are in the $1.2 billion range (-$154 million to $2.1 billion) when patients with lacunar strokes are treated nonacutely and $1.8 billion when those patients are admitted for acute care.

CONCLUSION

The results demonstrate the potential effect of implementing a CT angiography-CT perfusion protocol. In particular, prompt CT angiography-CT perfusion imaging could have an effect on the cost of acute care in the treatment of stroke.

Preparing medical students for a filmless environment: instruction on the preparation of electronic case presentations from PACS

RATIONALE AND OBJECTIVES

As the use of picture archiving and communication systems (PACS) expands and radiology departments become increasingly filmless, it will become increasingly necessary to teach physicians how to use PACS and download diagnostic images. The authors developed an instruction method in which medical students enrolled in a radiology clerkship were taught how to use the PACS, download digital images, and incorporate them into an electronic case presentation. The feasibility and potential benefits of this instructional method were studied prospectively.

MATERIALS AND METHODS

Between June and October 1999, all 36 medical students enrolled in Harvard Medical School's core radiology clerkship at Massachusetts General Hospital, Boston, were required to give an electronic radiology case presentation with images downloaded from the departmental PACS. They were taught how to download images, edit them, and then import them into PowerPoint software. They were also given access to the hospital information system to obtain pertinent clinical information. At the formal presentations, the images were displayed with a liquid crystal display (LCD) projector. The students were surveyed on the Ist and last days of the clerkship regarding their learning experiences.

RESULTS

Before the radiology clerkship, 81% of the students had never given an electronic presentation with computer and LCD projector, 83% had no PACS experience, and 56% had no PowerPoint experience. All students learned to prepare and deliver electronic presentations of radiologic cases downloaded from PACS. Their presentations were informative, innovative, and entertaining, and the images were well displayed. The students praised the instruction highly and thought their new skills would serve them well.

CONCLUSION

Teaching medical students how to prepare and deliver electronic presentations of radiologic cases downloaded from PACS proved to be very feasible and well appreciated by the students.

Patterning the early zebrafish by the opposing actions of bozozok and vox/vent

Fish and frog embryos are patterned along the dorsal-ventral axis during the gastrula stage by opposing gradients of Bmps and Bmp inhibitory proteins. Three transcriptional repressors with partially overlapping expression domains have been proposed to be important mediators of Bmp function in Xenopus. We find that two related factors are expressed in the early zebrafish embryo. Although these factors are considerably divergent from the related Xenopus genes, they are expressed in domains similar to those of their Xenopus relatives throughout embryogenesis. Both of the zebrafish genes, which we have named vox and vent, are potent ventralizing factors in both zebrafish and Xenopus embryos. Using mutants in the Bmp pathway, we find that there are Bmp-dependent and Bmp-independent domains of vox expression, whereas vent is mostly dependent upon Bmp signaling. We show that ectopic vox or vent negatively regulates expression of the early dorsal gene bozozok (boz) and that ectopic boz eliminates vox and vent expression. Moreover, the normal exclusion of vox and vent from the organizer region is lost in boz mutant embryos. Our results show that boz and vox/vent are mutually antagonistic and indicate that the early establishment of the size of the organizer domain is dependent on an interplay between these early expressed transcriptional repressors.

Early intervention and prevention of anxiety disorders in children: results at 2-year follow-up

The Queensland Early Intervention and Prevention of Anxiety Project evaluated a child- and family-focused group intervention for preventing anxiety problems in children. This article reports on 12- and 24-month follow-up data to previously reported outcomes at posttreatment and at 6-month follow-up. A total of 1,786 7- to 14-year-olds were screened for anxiety problems using teacher nominations and children's self-report. After diagnostic interviews, 128 children were selected and assigned to either a 10-week school-based child- and parent-focused psychosocial intervention or a monitoring group. Both groups showed improvements immediately at postintervention and at 6-month follow-up; the improvement was maintained in the intervention group only reducing the rate of existing anxiety disorder and preventing the onset of new anxiety disorders. At 12 months, the groups converged, but the superiority of the intervention group was evident again at 2-year follow-up. Severity of pretreatment diagnoses, gender, and parental anxiety predicted poor initial response to intervention, whereas pretreatment severity was the only predictor of chronicity at 24 months. Overall, follow-up results show that a brief school-based intervention for children can produce durable reductions in anxiety problems.

Early intervention and prevention of anxiety disorders in children: results at 2-year follow-up

The Queensland Early Intervention and Prevention of Anxiety Project evaluated a child- and family-focused group intervention for preventing anxiety problems in children. This article reports on 12- and 24-month follow-up data to previously reported outcomes at posttreatment and at 6-month follow-up. A total of 1,786 7- to 14-year-olds were screened for anxiety problems using teacher nominations and children's self-report. After diagnostic interviews, 128 children were selected and assigned to either a 10-week school-based child- and parent-focused psychosocial intervention or a monitoring group. Both groups showed improvements immediately at postintervention and at 6-month follow-up; the improvement was maintained in the intervention group only reducing the rate of existing anxiety disorder and preventing the onset of new anxiety disorders. At 12 months, the groups converged, but the superiority of the intervention group was evident again at 2-year follow-up. Severity of pretreatment diagnoses, gender, and parental anxiety predicted poor initial response to intervention, whereas pretreatment severity was the only predictor of chronicity at 24 months. Overall, follow-up results show that a brief school-based intervention for children can produce durable reductions in anxiety problems.

Cloning of a cryV-type insecticidal protein gene from Bacillus thuringiensis: the cryV-encoded protein is expressed early in stationary phase

A CryV-type protein (CGCryV) has been isolated from supernatant fluids of Bacillus thuringiensis AB88 cultures. Previous reports have suggested the cryptic nature of the cryV-type genes on the basis of the absence of CryV-type proteins in parasporal crystals. The CryV-type protein reported here is expressed early in stationary phase, and evidence indicates that it is an exported protein. Analysis of the deduced protein sequence from this gene reveals the presence of an N-terminal domain that likely acts as a signal peptide. The CGCryV protein is the first reported case of a delta-endotoxin being a secreted protein, which may influence the biological relevance of these proteins.

Adverse vascular effects of homocysteine are modulated by endothelium-derived relaxing factor and related oxides of nitrogen

Elevated levels of homocysteine are associated with an increased risk of atherosclerosis and thrombosis. The reactivity of the sulfhydryl group of homocysteine has been implicated in molecular mechanisms underlying this increased risk. There is also increasingly compelling evidence that thiols react in the presence of nitric oxide (NO) and endothelium-derived relaxing factor (EDRF) to form S-nitrosothiols, compounds with potent vasodilatory and antiplatelet effects. We, therefore, hypothesized that S-nitrosation of homocysteine would confer these beneficial bioactivities to the thiol, and at the same time attenuate its pathogenicity. We found that prolonged (> 3 h) exposure of endothelial cells to homocysteine results in impaired EDRF responses. By contrast, brief (15 min) exposure of endothelial cells, stimulated to secrete EDRF, to homocysteine results in the formation of S-NO-homocysteine, a potent antiplatelet agent and vasodilator. In contrast to homocysteine, S-NO-homocysteine does not support H2O2 generation and does not undergo conversion to homocysteine thiolactone, reaction products believed to contribute to endothelial toxicity. These results suggest that the normal endothelium modulates the potential, adverse effects of homocysteine by releasing EDRF and forming the adduct S-NO-homocysteine. The adverse vascular properties of homocysteine may result from an inability to sustain S-NO formation owing to a progressive imbalance between the production of NO by progressively dysfunctional endothelial cells and the levels of homocysteine.

S-nitrosylation of tissue-type plasminogen activator confers vasodilatory and antiplatelet properties on the enzyme

Tissue-type plasminogen activator (t-PA) reacts upon exposure to endothelium-derived relaxing factor (EDRF) by way of the enzyme's single free sulfhydryl (Cys-83) to form a stable S-nitrosothiol protein adduct. S-nitrosylation endows t-PA with potent vasodilatory and antiplatelet properties that are accompanied by elevations in intracellular cyclic GMP analogous to those induced by low molecular weight (e.g., S-nitroso amino acid) S-nitrosothiols. Moreover, this chemical modification does not adversely affect the catalytic efficiency of t-PA, the fibrin stimulation of this activity, the binding of t-PA to fibrinogen, or the interaction of the enzyme with its physiologic serine protease inhibitor, plasminogen-activator inhibitor type I. The coupling of vasodilatory, antiplatelet, and fibrinolytic properties in one molecule makes the S-nitrosylated t-PA a unique molecular species and may provide insight into the mechanisms by which the endothelium maintains vessel patency. These data also suggest a pharmacologic approach to treatment of thromboocclusive disorders.

Comparing autistic and normal children along the dimensions of reinforcement maximization, stimulus sampling, and responsiveness to extinction

The purpose of this study was to assess autistic children's ability to maximize reinforcement, sample among available stimuli, and respond to extinction. Responding to five concurrent reinforcement schedules (CRF, FR 2, FR 4, FR 7, and FR 11) was monitored and compared to groups of mental age-matched and chronological age-matched normal children. When a given child consistently selected a given schedule of reinforcement, it was then put on extinction, and both perseveration and responding to the remaining (intact) schedules of reinforcement were monitored. The results showed, first, that while normal children selected the richest schedule of reinforcement, autistics did not maximize reinforcement, typically selecting one of the thinner schedules available. Second, the autistic children sampled less, and less efficiently, than the normal children. Third, the autistic children proved to be much less responsive to extinction, perseverating longer than the normal children before switching to a new reinforcement schedule. Fourth, whenever extinction proved to be a problem in the autistics, it was quickly achieved by a simple change in the stimulus conditions. These results are discussed as possible "keystone" deficits, which may be causally related to many of the behavioral deficits of autism and which might be important target behaviors for treatment.