Rationality in medical decision making: a review of the literature on doctors' decision-making biases

The objectives of this study were to describe ways in which doctors make suboptimal diagnostic and treatment decisions, and to discuss possible means of alleviating those biases, using a review of past studies from the psychological and medical decision-making literatures. A number of biases can affect the ways in which doctors gather and use evidence in making diagnoses. Biases also exist in how doctors make treatment decisions once a definitive diagnosis has been made. These biases are not peculiar to the medical domain but, rather, are manifestations of suboptimal reasoning to which people are susceptible in general. None the less, they can have potentially grave consequences in medical settings, such as erroneous diagnosis or patient mismanagement. No surefire methods exist for eliminating biases in medical decision making, but there is some evidence that the adoption of an evidence-based medicine approach or the incorporation of formal decision analytic tools can improve the quality of doctors' reasoning. Doctors' reasoning is vulnerable to a number of biases that can lead to errors in diagnosis and treatment, but there are positive signs that means for alleviating some of these biases are available.

No long-term increase in cardiac-related mortality after breast-conserving surgery and radiation therapy using modern techniques

PURPOSE

To determine whether left-breast irradiation using modern techniques after breast-conserving surgery leads to an increased risk of cardiac-related mortality.

METHODS

Between 1968 and 1986, 1,624 patients were treated for unilateral stage I or II breast cancer at the Joint Center for Radiation Therapy, Harvard Medical School, Boston, MA, with conservative surgery and breast irradiation. Seven hundred forty-five patients with a potential follow-up of at least 12 years were analyzed. Clinical, pathologic, and treatment characteristics were compared between the 365 patients (49%) who received left-sided irradiation and the 380 patients (51%) who received right-sided irradiation. The relationship between left-sided breast irradiation and the risk of nonbreast cancer- and cardiac-related mortality was examined.

RESULTS

There was no significant difference in the distribution of clinical, pathologic, or treatment characteristics between the two groups, with the exception of a small difference in pathologic tumor size (medians, left, 2.0 cm, right, 1.5 cm; P = .007). At 12 years, a majority of patients still were alive. Slightly more patients with left-sided tumors had died of breast cancer (31% v 27%; P = NS). Equivalent proportions from each group died of nonbreast cancer causes (11%), including nine patients (2%) from each group who died from cardiac causes. The risk of cardiac mortality did not increase as time after treatment increased for patients who received left-sided irradiation compared with right-sided irradiation. A model that controlled for clinical, pathologic, and treatment differences showed no significant increase in any category of cause of death (breast, cardiac, or other) for patients who received left-sided irradiation.

CONCLUSION

These results suggest that modern breast radiotherapy is not associated with an increased risk of cardiac-related mortality within at least the first 12 years after treatment.

Reduction of cardiac volume in left-breast treatment fields by respiratory maneuvers: a CT study

PURPOSE

A previous study of healthy female volunteers suggested that deep inspiratory breath holding can reduce the cardiac volume in the treatment portals for left-breast cancer treatment. The reduction of irradiated cardiac volume may be important considering the reported late cardiac morbidity and mortality and the frequent coexistent use of potentially cardiotoxic chemotherapy in breast cancer patients. In the present study, we evaluated the heart volume in the fields and, thus, the true benefit of this respiratory maneuver in breast cancer patients undergoing CT simulation.

MATERIALS AND METHODS

Fifteen patients (median age, 53) were studied. For each patient, CT scans were performed both when the patient breathed normally (quiet respiration) and when the patient held her breath after a deep inspiration. Tangential fields were planned using the same medial, lateral, superior, and inferior borders on skin for the normal breathing and the breath-holding configurations. The cardiac and left-lung volumes within the tangential fields were calculated for both breathing configurations. Multiple scan series were performed for the breath-holding configuration to provide a more accurate delineation of the cardiac tissue and to study the reproducibility of the patient's position between different cycles of deep inspiration.

RESULTS

None of the patients had difficulty holding her breath for 20 s. The cardiac volume in the field was reduced (-86 +/- 24%; p < 0.001) when patients held their breath after a deep inspiration compared to when breathing normally. For 7 patients (47%), deep inspiration moved the heart completely out of the radiation fields. The expansion of the lung tissue due to deep inspiration also increased the absolute lung volume in the tangential fields (183 cm(3) vs 97 cm(3), p < 0.001). However, the fractional volume of the left lung in the field was essentially unchanged. For all but 1 patient, the maximum difference between the external body contours from different breath holding cycles was 5 mm and occurred at the lateral aspect of the breast. At the medial aspect, as indicated by the position of the midline marker, the variations were well within the currently accepted tolerance for patient positioning during tangential treatment.

CONCLUSIONS

Deep-inspiration breath holding substantially reduces cardiac volume in the tangential fields for left-sided breast cancer treatment. The variation between patient positions at different cycles of breath holding was found to be reasonably small. Therefore, it appears feasible to reduce cardiac radiation by treating patients with intratreatment minifractions lasting 10-15 s while patients hold their breath.

The relation between the presence and extent of lobular carcinoma in situ and the risk of local recurrence for patients with infiltrating carcinoma of the breast treated with conservative surgery and radiation therapy

BACKGROUND

When found in an otherwise benign biopsy, lobular carcinoma in situ (LCIS) has been associated with an increased risk of development of a subsequent invasive breast carcinoma. However, the association between LCIS and the risk of subsequent local recurrence in patients with infiltrating carcinoma treated with conservative surgery and radiation therapy has received relatively little attention.

METHODS

Between 1968 and 1986, 1625 patients with clinical Stage I-II invasive breast carcinoma were treated at the Joint Center for Radiation Therapy at Harvard Medical School with breast-conserving surgery (CS) and radiation therapy (RT) to a total dose to the primary site of > or =60 grays. Analysis was limited to 1181 patients with infiltrating ductal carcinoma, infiltrating lobular carcinoma, or infiltrating carcinoma with mixed ductal and lobular features who, on review of their histologic slides, had sufficient normal tissue adjacent to the tumor to evaluate for the presence of LCIS and also had a minimum potential follow-up time of 8 years. The median follow-up time was 161 months.

RESULTS

One hundred thirty-seven patients (12%) had LCIS either within the tumor or in the macroscopically normal adjacent tissue. The 8-year crude risk of recurrence was not significantly increased for patients with LCIS associated with invasive ductal, invasive lobular, or mixed ductal and lobular carcinoma. Among the 119 patients with associated LCIS adjacent to the tumor, the 8-year rate of local recurrence was 13%, compared with 12% for the 1062 patients without associated LCIS. For the 70 patients with moderate or marked LCIS adjacent to the tumor, the 8-year rate of local recurrence was 13%. The extent of LCIS did not affect the risk of recurrence. The risks of contralateral disease and of distant failure were similarly not affected by the presence or extent of LCIS.

CONCLUSIONS

Breast-conserving therapy involving limited surgery and radiation therapy is an appropriate method of treating patients with invasive breast carcinoma with or without associated LCIS. Neither the presence nor the extent of LCIS should influence management decisions regarding patients with invasive breast carcinoma. [See editorial counterpoint and reply to counterpoint on pages 978-81 and 982-3, this issue.]

Choosing a doctor: an exploratory study of factors influencing patients' choice of a primary care doctor

We assessed the relative importance healthcare consumers attach to various factors in choosing a primary care doctor (PCD) in a cross-sectional, in-person survey. Three survey locations were used: doctors' offices, a public shopping area, and meetings of a women's organization. A total of 636 community residents, varying across major demographic categories, participated. Participants completed a 23-item survey, designed to assess which factors consumers perceive as most relevant in choosing a PCD. Participants perceived professionally relevant factors (e.g. whether the doctor is board certified, office appearance) and management practices (e.g. time to get an appointment, evening and weekend hours) as more important than the doctor's personal characteristics (race, age, gender, etc.). Participants' own characteristics bore little relationship to the perceived importance of doctor characteristics. Factors patients perceive as most important to their choice of a PCD are also those that have the greatest effect on the quality of healthcare they will receive. However, they do not always have access to this information. A better understanding of the factors that influence people's choice of a PCD can contribute to efforts to provide them with the resources to make well-informed decisions in selecting among healthcare options.

Locally advanced rectal carcinoma: pelvic control and morbidity following preoperative radiation therapy, resection, and intraoperative radiation therapy

PURPOSE

To determine the impact of intraoperative radiation therapy (IORT) combined with preoperative external beam irradiation and surgical resection in patients with locally advanced, unresectable rectal carcinoma.

METHODS AND MATERIALS

Between 1982 and 1993, 40 patients with locally advanced colorectal cancer unresectable at initial presentation were treated with preoperative external beam radiation therapy (median dose 50.4 Gy). Thirty patients received concurrent 5-fluorouracil. Twenty-seven patients had primary tumors and 13 had recurrent disease; 1 patient had a solitary hepatic metastasis at the time of surgery. Four to 6 weeks after radiation, surgical resection was undertaken, and if microscopic or gross residual disease was encountered, IORT was delivered to the tumor bed. Patients with an unevaluable or high-risk margin were also considered for IORT. IORT was delivered through a dedicated 300-kVp orthovoltage unit. The median dose of IORT was 12.5 Gy (range 8-20). The dose was typically prescribed to a depth of 1-2 cm. The median follow-up was 33 months (range 5-100).

RESULTS

Thirty-three patients were able to undergo a curative resection (83%). Five patients had gross residual disease despite aggressive surgery. Seven patients did not receive IORT: six because of clear margins, and one with gross disease that could not be treated for technical reasons. The remainder of the patients (26) received IORT to the site of pelvic adherence. The crude local control rates for patients following complete resection with negative margins were 92% for patients treated with IORT and 33% for patients without IORT. IORT was ineffective for gross residual disease. Pelvic control was none of four in this setting. The crude local control rate of patients with primary cancer was 73% (16 of 22), as opposed to 27% (3 of 11) for these with recurrent cancer. The 5-year actuarial overall survival and local control rates for patients undergoing gross complete resection and IORT were 64% and 75%, respectively. Seventeen of the 26 patients (65%) who received IORT experienced pelvic complications, as opposed to two patients (28%) who did not receive IORT. The incidence of complications was similar in the patients with primary versus recurrent disease. All cases were successfully treated with the placement of a posterior thigh myocutaneous flap. Of note, no pelvic osteoradionecrosis was seen in this series.

CONCLUSION

Patients with locally advanced carcinoma of the rectum were aggressively treated with combined modality therapy consisting of preoperative external beam radiotherapy, surgery, and IORT. The pelvic control rate was 82% for patients with minimal residual disease. IORT failed to control gross residual disease. The incidence of pelvic wound healing problems was 65% in this series; however, a reconstructive procedure which replaced irradiated tissue with a vascularized myocutaneous flap was successful in treating this complication. We believe that IORT has therapeutic merit in the treatment of locally advanced rectal cancer, particularly in the setting of minimal residual disease.

Registered Replication Report: Schooler and Engstler-Schooler (1990)

Trying to remember something now typically improves your ability to remember it later. However, after watching a video of a simulated bank robbery, participants who verbally described the robber were 25% worse at identifying the robber in a lineup than were participants who instead listed U.S. states and capitals-this has been termed the "verbal overshadowing" effect (Schooler & Engstler-Schooler, 1990). More recent studies suggested that this effect might be substantially smaller than first reported. Given uncertainty about the effect size, the influence of this finding in the memory literature, and its practical importance for police procedures, we conducted two collections of preregistered direct replications (RRR1 and RRR2) that differed only in the order of the description task and a filler task. In RRR1, when the description task immediately followed the robbery, participants who provided a description were 4% less likely to select the robber than were those in the control condition. In RRR2, when the description was delayed by 20 min, they were 16% less likely to select the robber. These findings reveal a robust verbal overshadowing effect that is strongly influenced by the relative timing of the tasks. The discussion considers further implications of these replications for our understanding of verbal overshadowing.

Family history and treatment outcome in young women after breast-conserving surgery and radiation therapy for early-stage breast cancer

PURPOSE

To evaluate the safety and efficacy of breast-conserving therapy for young women with a family history (FH) suggestive of inherited breast cancer susceptibility.

MATERIALS AND METHODS

A total of 201 patients aged 36 or younger at diagnosis treated with breast-conserving surgery and radiation therapy (> or = 60 Gy) for early-stage breast cancer were categorized by FH. FH was considered positive in 29 patients who, at the time of diagnosis, had a mother or sister previously diagnosed with breast cancer before age 50 or ovarian cancer at any age. Clinical, pathologic, and demographic variables; sites of first failure; disease-free survival; and overall survival (OS) were compared between FH-positive and -negative groups. Median follow-up time was 11 years.

RESULTS

Patient and tumor features were similar between those with and without an FH. Regression analysis of sites of first failure at 5 years demonstrated a risk ratio (RR) of 5.7 for opposite breast cancer for FH-positive patients. Rates of local, regional, and distant failure and disease-free survival or OS did not differ between FH-positive and -negative patients. Age at diagnosis and Ashkenazi heritage were not significantly predictors of patterns of failure.

CONCLUSION

Breast-conserving surgery combined with radiation therapy is not associated with a higher rate of local recurrence, distant failure, or second (non-breast) cancers in young women with an FH suggestive of inherited breast cancer susceptibility compared with young women without an FH. However, their increased risk of opposite breast cancer should be taken into account when considering breast conservation as a treatment option.

AEGIS autonomous targeting for ChemCam on Mars Science Laboratory: Deployment and results of initial science team use

Limitations on interplanetary communications create operations latencies and slow progress in planetary surface missions, with particular challenges to narrow-field-of-view science instruments requiring precise targeting. The AEGIS (Autonomous Exploration for Gathering Increased Science) autonomous targeting system has been in routine use on NASA's Curiosity Mars rover since May 2016, selecting targets for the ChemCam remote geochemical spectrometer instrument. AEGIS operates in two modes; in autonomous target selection, it identifies geological targets in images from the rover's navigation cameras, choosing for itself targets that match the parameters specified by mission scientists the most, and immediately measures them with ChemCam, without Earth in the loop. In autonomous pointing refinement, the system corrects small pointing errors on the order of a few milliradians in observations targeted by operators on Earth, allowing very small features to be observed reliably on the first attempt. AEGIS consistently recognizes and selects the geological materials requested of it, parsing and interpreting geological scenes in tens to hundreds of seconds with very limited computing resources. Performance in autonomously selecting the most desired target material over the last 2.5 kilometers of driving into previously unexplored terrain exceeds 93% (where ~24% is expected without intelligent targeting), and all observations resulted in a successful geochemical observation. The system has substantially reduced lost time on the mission and markedly increased the pace of data collection with ChemCam. AEGIS autonomy has rapidly been adopted as an exploration tool by the mission scientists and has influenced their strategy for exploring the rover's environment.

Mutation analysis in 16 patients with mtDNA depletion

Sixteen unrelated Southern European patients with the mitochondrial depletion syndrome (MDS) were analyzed for mutations in the TK2 and DGUOK genes. Three novel mutations were identified in TK2 (R183G, R254X, and 142insG). When we analyzed additional genes involved in the dNTPs pool, such as SLC25A19 (DNC) and NT5M (d-NT2), we did not detect mutations. The current study suggest that scanning the TK2, DGUOK, SLC25A19, and NT5M genes is likely to help about 10% of MDS families in terms of genetic counseling. Also, our findings indicate that genotype-phenotype correlations are not straightforward in MDS.

Heat shock stimulates the release of arachidonic acid and the synthesis of prostaglandins and leukotriene B4 in mammalian cells

Heat shock has a profound influence on the metabolism and behavior of eukaryotic cells. We have examined the effects of heat shock on the release from cells of arachidonic acid and its bioactive eicosanoid metabolites, the prostaglandins and leukotrienes. Heat shock (42-45 degrees) increased the rate of arachidonic acid release from human, rat, murine, and hamster cells. Arachidonate accumulation appeared to be due, at least partially, to stimulation of a phospholipase A2 activity by heat shock and was accompanied by the accumulation of lysophosphatidyl-inositol and lysophosphatidylcholine in membranes. Induction of arachidonate release by heat did not appear to be mediated by an increase in cell Ca++. Stimulation of arachidonate release by heat shock in hamster fibroblasts was quantitatively similar to the receptor-mediated effects of alpha thrombin and bradykinin. The effects of heat shock and alpha thrombin on arachidonate release were inhibited by glucocorticoids. Increased arachidonate release in heat-shocked cells was accompanied by the accelerated accumulation of cyclooxygenase products prostaglandin E2 and prostaglandin F2 alpha and by 5-lipoxygenase metabolite leukotriene B4. Elevated concentrations of arachidonic acid and metabolites may be involved in the cytotoxic effects of hyperthermia, in homeostatic responses to heat shock, and in vascular and inflammatory reactions to stress.

Early-onset multisystem mitochondrial disorder caused by a nonsense mutation in the mitochondrial DNA cytochrome C oxidase II gene

We report the first nonsense mutation (G7896A) in the mtDNA gene for subunit II of cytochrome c oxidase (COX) in a patient with early-onset multisystem disease and COX deficiency in muscle. The mutation was heteroplasmic in muscle, blood, and fibroblasts from the patient and abundantly present in COX-deficient fibers, but less abundant in COX-positive fibers; it was not found in blood samples from the patient's asymptomatic maternal relatives. Immunoblot analysis showed a reduced concentration of both COX II and COX I polypeptides, suggesting impaired assembly of COX holoenzyme.

Relationship of tumor grade to other pathologic features and to treatment outcome of patients with early stage breast carcinoma treated with breast-conserving therapy

BACKGROUND

Although histologic grade has previously been described as a predictor of distant failure, it is uncertain whether histologic grade should be used to decide which patients should undergo axillary lymph node dissection and whether grade should be considered as a selection factor for breast-conserving therapy.

METHODS

The authors retrospectively analyzed data from 1081 patients with American Joint Committee on Cancer Stage I or II infiltrating ductal carcinoma treated with breast-conserving therapy at the Joint Center for Radiation Therapy between 1970 and 1986. All patients had pathology slides reviewed by one of two study pathologists. Using the Elston modification of the Bloom-Richardson grading system, patients were divided by histologic grade into 3 groups (219 with Grade I, 482 with Grade II, and 380 with Grade III). The median follow-up time for 716 survivors was 134 months. The incidence of various pathologic features was examined with respect to histologic grade. In addition, the 10-year crude rates of failure (by first site) were examined as they related to grade. A polychotomous logistic regression model was used to determine the effect of grade on local and distant failure.

RESULTS

High grade tumors tended to be larger, to exhibit more mononuclear cellular reaction and necrosis, and were more likely to be estrogen receptor negative. Patients with high grade tumors were also younger than those with lower grade tumors. The incidence of an extensive intraductal component and lymphatic vessel invasion did not vary significantly by histologic grade. The incidence of pathologic lymph node metastases also did not vary by grade, even when stratified by tumor size. In both univariable and multivariable analyses, the 10-year crude rate of local recurrence was not related to histologic grade (P = 0.44). Distant recurrence rates, however, were significantly higher as grade increased (p = 0.002).

CONCLUSIONS

Higher histologic grade predicted an increased incidence of distant recurrence, but not a greater likelihood of axillary lymph node metastases or local recurrence after breast-conserving therapy. The authors conclude that grade should not be used to make decisions regarding local management.

The IAP-antagonist ARTS initiates caspase activation upstream of cytochrome C and SMAC/Diablo

ARTS (Sept4_i2) is a pro-apoptotic tumor suppressor protein that functions as an antagonist of X-linked IAP (XIAP) to promote apoptosis. It is generally thought that mitochondrial outer membrane permeabilization (MOMP) occurs before activation of caspases and is required for it. Here, we show that ARTS initiates caspase activation upstream of MOMP. In living cells, ARTS is localized to the mitochondrial outer membrane. In response to apoptotic signals, ARTS translocates rapidly to the cytosol in a caspase-independent manner, where it binds XIAP and promotes caspase activation. This translocation precedes the release of cytochrome C and SMAC/Diablo, and ARTS function is required for the normal timing of MOMP. We also show that ARTS-induced caspase activation leads to cleavage of the pro-apoptotic Bcl-2 family protein Bid, known to promote MOMP. We propose that translocation of ARTS initiates a first wave of caspase activation that can promote MOMP. This leads to the subsequent release of additional mitochondrial factors, including cytochrome C and SMAC/Diablo, which then amplifies the caspase cascade and causes apoptosis.

Detection of tilapia lake virus (TiLV) infection by PCR in farmed and wild Nile tilapia (Oreochromis niloticus) from Lake Victoria

Tilapia lake virus disease (TiLVD) has emerged to be an important viral disease of farmed Nile tilapia (Oreochromis niloticus) having the potential to impede expansion of aquaculture production. There is a need for rapid diagnostic tools to identify infected fish to limit the spread in individual farms. We report the first detection of TiLV infection by PCR in farmed and wild Nile tilapia from Lake Victoria. There was no difference in prevalence between farmed and wild fish samples (p = .65), and of the 442 samples examined from 191 fish, 28 were positive for TiLV by PCR. In terms of tissue distribution, the head kidney (7.69%, N = 65) and spleen (10.99%, N = 191), samples had the highest prevalence (p < .0028) followed by heart samples (3.45%, N = 29). Conversely, the prevalence was low in the liver (0.71%, N = 140) and absent in brain samples (0.0%, N = 17), which have previously been shown to be target organs during acute infections. Phylogenetic analysis showed homology between our sequences and those from recent outbreaks in Israel and Thailand. Given that these findings were based on nucleic acid detection by PCR, future studies should seek to isolate the virus from fish in Lake Victoria and show its ability to cause disease and virulence in susceptible fish.

A double mutation (A8296G and G8363A) in the mitochondrial DNA tRNA (Lys) gene associated with myoclonus epilepsy with ragged-red fibers

OBJECTIVE

To define potential pathogenic mitochondrial DNA (mtDNA) point mutations in a patient with myoclonus epilepsy with ragged-red fibers (MERRF) syndrome.

BACKGROUND

MERRF syndrome is typically associated with point mutations in the mtDNA tRNALys gene.

METHODS

We performed morphologic, biochemical, and genetic analysis of muscle samples from the patient and four relatives. Molecular genetic studies included sequencing, PCR, and restriction enzyme analysis on whole muscle, blood, and single muscle fibers.

RESULTS

Muscle biopsy showed cytochrome c oxidase (COX), negative ragged-red fibers (RRF), and a defect of complex I of the mitochondrial respiratory chain. We found an A8296G transition and a G8363A mutation in the mtDNA tRNALYs gene. The A8296G was almost homoplasmic in muscle and blood from the propositus and his oligosymptomatic maternal relatives. The G8363A mutation was heteroplasmic and more abundant in muscle than in blood, and its proportion correlated with clinical severity. Single muscle fiber analysis showed significantly higher levels of G8363A genomes in COX-negative than in normal fibers, and almost homoplasmic levels of mutant A8296G mtDNA in both COX-negative and normal fibers. The two mutations affect highly conserved nucleotides and were not found in controls.

CONCLUSIONS

The G8363A mutation is pathogenic; the co-occurrence of the A8296G mutation is of unclear significance and is likely to be a rare polymorphism.

Mitochondrial dysfunction associated with a mutation in the Notch3 gene in a CADASIL family

BACKGROUND

Cerebral autosomal arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is characterized by recurrent subcortical ischemic strokes and dementia caused by mutations in the Notch3 gene. In Drosophila melanogaster, Notch signaling has a pleiotropic effect, affecting most tissues of the organism during development.

OBJECTIVE

To characterize a potential mitochondrial dysfunction associated with mutations in the Notch3 gene.

METHODS

Biochemical, histochemical, molecular, and genetic analyses were performed on muscle biopsy specimens and fibroblasts obtained from patients of a Spanish family with CADASIL. Additional biochemical and molecular analyses of the N(55e11) mutant of D. melanogaster were performed.

RESULTS

In muscle biopsy specimens, a significant decrease was found in the activity of complex I (NADH [reduced form of nicotinamide adenine dinucleotide] dehydrogenase), and in one patient, histochemical analysis showed the presence of ragged-red fibers with abnormal cytochrome c oxidase staining. Reduced fibroblast activity of complex V (ATP synthase) was found. Supporting data on patients with CADASIL, it was found that the mutation N(55e11) in Drosophila decreases the activity of mitochondrial respiratory complexes I and V.

CONCLUSIONS

Mitochondrial respiratory chain activity responds, directly or indirectly, to the Notch signaling pathway. Mitochondrial dysfunction in patients with CADASIL may be an epiphenomenon, but results of this study suggest that the pathophysiology of the disease could include a defect in oxidative phosphorylation.

Rationality in medical treatment decisions: is there a sunk-cost effect?

OBJECTIVE

To assess residents' propensity to display the sunk-cost effect, an irrational decision-making bias, in medical treatment decisions; and to compare residents' and undergraduates' susceptibility to the bias in non-medical, everyday behaviors.

DESIGN

Cross-sectional, in-person survey.

SETTING

Louisiana State University, two locations: Medical Center-Baton Rouge and Main Campus-Psychology Department.

PARTICIPANTS

Internal medicine and family practice residents (N = 36, Mdn age = 27) and college undergraduates (N = 40, Mdn age = 20).

MEASUREMENTS AND MAIN RESULTS

Residents evaluated medical and non-medical situations that varied the amount of previous investment and whether the present decision maker was the same or different from the person who had made the initial investment. They rated reasons both for continuing the initial decision (e.g., stay with the medication already in use) and for switching to a new alternative (e.g., a different medication). There were two main findings: First, the residents' ratings of whether to continue or switch medical treatments were not influenced by the amount of the initial investment (p's>0.05). Second, residents' reasoning was more normative in medical than in non-medical situations, in which it paralleled that of undergraduates (p's<0.05).

CONCLUSIONS

Medical residents' evaluation of treatment decisions reflected good reasoning, in that they were not influenced by the amount of time and/or money that had already been invested in treating a patient. However, the residents did demonstrate a sunk-cost effect in evaluating non-medical situations. Thus, any advantage in decision making that is conferred by medical training appears to be domain specific.

Structure and regulated expression of the delta-aminolevulinate synthase gene from Drosophila melanogaster

The structure of the single copy gene encoding the putative housekeeping isoform of Drosophila melanogaster delta-aminolevulinate synthase (ALAS) has been determined. Southern and immunoblot analyses suggest that only the housekeeping isoform of the enzyme exists in Drosophila. We have localized a critical region for promoter activity to a sequence of 121 base pairs that contains a motif that is potentially recognized by factors of the nuclear respiratory factor-1 (NRF-1)/P3A2 family, flanked by two AP4 sites. Heme inhibits the expression of the gene by blocking the interaction of putative regulatory proteins to its 5' proximal region, a mechanism different from those proposed for other hemin-regulated promoters. Northern and in situ RNA hybridization experiments show that maternal alas mRNA is stored in the egg; its steady-state level decreases rapidly during the first hours of development and increases again after gastrulation in a period where the synthesis of several mRNAs encoding metabolic enzymes is activated. In the syncytial blastoderm, the alas mRNA is ubiquitously distributed and decreases in abundance substantially through cellular blastoderm. Late in embryonic development alas shows a specific pattern of expression, with an elevated mRNA level in oenocytes, suggesting an important role of these cells in the biosynthesis of hemoproteins in Drosophila.

The revelation effect in frequency judgment

In three experiments, we explored the revelation effect in a frequency judgment task. Participants estimated the frequency of words that had been presented one, two, four, or eight times. At test, half the words were revealed by completing word fragments, and half were presented intact. Estimated frequencies were reliably higher for revealed than for intact words, and in two of the three experiments, the revelation effect became larger as actual frequency increased. A revelation effect was obtained whether the revealed word was the same as (Experiment 1) or different from (Experiment 2) the word judged for frequency. Frequency estimates were higher for more distorted test items (Experiment 3).

Effects of L-carnitine on erythrocyte acyl-CoA, free CoA, and glycerophospholipid acyltransferase in uremia

We studied the effects of L-carnitine treatment in the acyl flux of erythrocyte membranes from uremic patients. We found a significantly lower relative proportion of long-chain acyl-CoA (LCCoA) to free CoA (FCoA) in patients than in control subjects. In addition, patients had reduced activities of both carnitine palmitoyltransferase (CPT) and glycerophospholipid acyltransferase (LAT; CoA dependent), and increased ratios of long-chain acylcarnitine (LCAC) to free carnitine in their erythrocytes. These data support the hypothesis that acyl-trafficking is altered in erythrocytes in uremia. After treatment with L-carnitine, we observed a significant increase in CPT and LAT activities as well as in the LCCoA-FCoA ratio, and a significant decrease in the ratio of LCAC to free carnitine. These results support the conclusion that L-carnitine supplementation improves erythrocyte flux in uremic patients.