Facial first impressions are not mandatory: A priming investigation

A common assertion is that, based around prominent character traits, first impressions are spontaneously extracted from faces. Specifically, mere exposure to a person is sufficient to trigger the involuntary extraction of core personality characteristics (e.g., trustworthiness, dominance, competence), an outcome that supports a range of significant judgments (e.g., hiring, investing, electing). But is this in fact the case? Noting ambiguities in the extant literature, here we used a repetition priming procedure to probe the extent to which impressions of dominance are extracted from faces absent the instruction to evaluate the stimuli in this way. Across five experiments in which either the character trait of interest was made increasingly obvious to participants (Expts. 1-3) or attention was explicitly directed toward the faces to generate low-level/high-level judgments (Expts. 4 & 5), no evidence for the spontaneous extraction of first impressions was observed. Instead, priming only emerged when judgments of dominance were an explicit requirement of the task at hand. Thus, at least using a priming methodology, the current findings contest the notion that first impressions are a mandatory product of person perception.

The power of the unexpected: Prediction errors enhance stereotype-based learning

Stereotyping is a ubiquitous feature of social cognition, yet surprisingly little is known about how group-related beliefs influence the acquisition of person knowledge. Accordingly, in combination with computational modeling (i.e., Reinforcement Learning Drift Diffusion Model analysis), here we used a probabilistic selection task to explore the extent to which gender stereotypes impact instrumental learning. Several theoretically interesting effects were observed. First, reflecting the impact of cultural socialization on person construal, an expectancy-based preference for stereotype-consistent (vs. stereotype-inconsistent) responses was observed. Second, underscoring the potency of unexpected information, learning rates were faster for counter-stereotypic compared to stereotypic individuals, both for negative and positive prediction errors. Collectively, these findings are consistent with predictive accounts of social perception and have implications for the conditions under which stereotyping can potentially be reduced.

People perception and stereotype-based responding: task context matters

Whether group impact social perception is a topic of renewed theoretical and empirical interest. In particular, it remains unclear when and how the composition of a group influences a core component of social cognition-stereotype-based responding. Accordingly, exploring this issue, here we investigated the extent to which different task requirements moderate the stereotype-related products of people perception. Following the presentation of same-sex groups that varied in facial typicality (i.e., high or low femininity/masculinity), participants had to report either the gender-related status of target words (i.e., a group-irrelevant gender-classification task) or whether the items were stereotypic or counter-stereotypic with respect to the preceding groups (i.e., a group-relevant stereotype-status task). Critically, facial typicality only impacted performance in the stereotype-status task. A further computational analysis (i.e., Diffusion Model) traced this effect to the combined operation of stimulus processing and response biases during decision-making. Specifically, evidence accumulation was faster when targets followed groups that were high (vs. low) in typicality and these arrays also triggered a stronger bias toward stereotypic (vs. counter-stereotypic) responses. Collectively, these findings elucidate when and how group variability influences people perception.

Comparing person and people perception: Multiple group members do not increase stereotype priming

A characteristic feature of daily life is encountering people in groups. Surprisingly, however, at least during the initial stages of processing, research has focused almost exclusively on the construal of single individuals. As such, it remains unclear whether person and people (i.e., group) perception yield comparable or divergent outcomes. Addressing this issue, here we explored a core social-cognitive topic-stereotype activation-by presenting both single and multiple facial primes in a sequential-priming task. In addition, the processes underlying task performance were probed using a drift diffusion model analysis. Based on prior work, it was hypothesised that multiple (vs. single) primes would increase stereotype-based responding. Across two experiments, a consistent pattern of results emerged. First, stereotype priming was insensitive to the number of primes that were presented and occurred only at a short prime-target stimulus onset asynchrony (i.e., 250 ms). Second, priming was underpinned by a bias towards congruent (vs. incongruent) prime-target responses. Collectively these findings advance understanding of the emergence and origin of stereotype priming during person and people perception.

More or less of me and you: self-relevance augments the effects of item probability on stimulus prioritization

Self-relevance exerts a powerful influence on information processing. Compared to material associated with other people, personally meaningful stimuli are prioritized during decision-making. Further exploring the character of this effect, here we considered the extent to which stimulus enhancement is impacted by the frequency of self-relevant versus friend-relevant material. In a matching task, participants reported whether shape-label stimulus pairs corresponded to previously learned associations (e.g., triangle = self, square = friend). Crucially however, before the task commenced, stimulus-based expectancies were provided indicating the probability with which both self- and friend-related shapes would be encountered. The results revealed that task performance was impacted by the frequency of stimulus presentation in combination with the personal relevance of the items. When self- and friend-related shapes appeared with equal frequencies, a self-prioritization effect emerged (Expt. 1). Additionally, in both confirmatory (Expt. 2) and dis-confirmatory (Expt. 3) task contexts, stimuli that were encountered frequently (vs. infrequently) were prioritized, an effect that was most pronounced for self-relevant (vs. friend-relevant) items. Further computational analyses indicated that, in each of the reported experiments, differences in performance were underpinned by variation in the rate of information uptake, with evidence extracted more rapidly from self-relevant compared to friend-relevant stimuli. These findings advance our understanding of the emergence and origin of stimulus-prioritization effects during decisional processing.

Self-prioritization during stimulus processing is not obligatory

An emerging literature has suggested that self-relevance automatically enhances stimulus processing (i.e., the self-prioritization effect). Specifically, during shape-label matching tasks, geometric shapes associated with the self are identified more rapidly than comparable stimuli paired with other targets (e.g., friend, stranger). Replicating and extending work that challenges the putative automaticity of this effect, here we hypothesized that self-relevance facilitates stimulus processing only when task sets draw attention to previously formed shape-label associations in memory. The results of a shape-classification task confirmed this prediction. Compared to shapes associated with a friend, those paired with the self were classified more rapidly when participants were required to report who the stimulus denoted (i.e., self or friend). In contrast, self-relevance failed to facilitate performance when participants judged either what the shape was (i.e., triangle or square, diamond or circle) or where it was located on the screen (i.e., above or below fixation). These findings further elucidate the conditions under which self-relevance does-and does not-influence stimulus processing.

Stereotype-based priming without stereotype activation: A tale of two priming tasks

An extensive literature has demonstrated stereotype-based priming effects. What this work has only recently considered, however, is the extent to which priming is moderated by the adoption of different sequential-priming tasks and the attendant implications for theoretical treatments of person perception. In addition, the processes through which priming arises (i.e., stimulus and/or response biases) remain largely unspecified. Accordingly, here we explored the emergence and origin of stereotype-based priming using both semantic- and response-priming tasks. Corroborating previous research, a stereotype-based priming effect only emerged when a response-priming (vs. semantic-priming) task was used. A further hierarchical drift diffusion model analysis revealed that this effect was underpinned by differences in the evidential requirements of response generation (i.e., a response bias), such that less evidence was needed when generating stereotype-consistent compared with stereotype-inconsistent responses. Crucially, information uptake (i.e., stimulus bias, efficiency of target processing) was faster for stereotype-inconsistent than stereotype-consistent targets. This reveals that stereotype-based priming originated in a response bias rather than the automatic activation of stereotypes. The theoretical implications of these findings are considered.

It's not always about me: The effects of prior beliefs and stimulus prevalence on self-other prioritisation

Although self-relevance is widely acknowledged to enhance stimulus processing, the exclusivity of this effect remains open to question. In particular, in commonly adopted experimental paradigms, the prioritisation of self-relevant (vs. other-relevant) material may reflect the operation of a task-specific strategy rather than an obligatory facet of social-cognitive functioning. By changing basic aspects of the decisional context, it may therefore be possible to generate stimulus-prioritisation effects for targets other than the self. Based on the demonstration that ownership facilitates object categorisation (i.e., self-ownership effect), here we showed that stimulus prioritisation is sensitive to prior expectations about the prevalence of forthcoming objects (owned-by-self vs. owned-by-friend) and whether these beliefs are supported during the task. Under conditions of stimulus uncertainty (i.e., no prior beliefs), replicating previous research, objects were classified more rapidly when owned-by-self compared with owned-by-friend (Experiment 1). When, however, the frequency of stimulus presentation either confirmed (Experiment 2) or disconfirmed (Experiment 3) prior expectations, stimulus prioritisation was observed for the most prevalent objects regardless of their owner. A hierarchical drift diffusion model (HDDM) analysis further revealed that decisional bias was underpinned by differences in the evidential requirements of response generation. These findings underscore the flexibility of ownership effects (i.e., stimulus prioritisation) during object processing.

Self-relevance enhances evidence gathering during decision-making

Despite repeated demonstrations that self-relevant material is prioritized during stimulus appraisal, a number of unresolved issues remain. In particular, it is unclear if self-relevance facilitates task performance when stimuli are encountered under challenging processing conditions. To explore this issue, using a backward masking procedure, here participants were required to report if briefly presented objects (pencils and pens) had previously been assigned to the self or a best friend (i.e., object-ownership task). The results yielded a standard self-ownership effect, such that responses were faster and more accurate to self-owned (vs. friend-owned) objects. In addition, a drift diffusion model analysis indicated that this effect was underpinned by a stimulus bias. Specifically, evidence was accumulated more rapidly from self-owned compared to friend-owned stimuli. These findings further elucidate the extent and origin of self-prioritization during decisional processing.

Predictably confirmatory: The influence of stereotypes during decisional processing

Stereotypes facilitate the processing of expectancy-consistent (vs expectancy-inconsistent) information, yet the underlying origin of this congruency effect remains unknown. As such, here we sought to identify the cognitive operations through which stereotypes influence decisional processing. In six experiments, participants responded to stimuli that were consistent or inconsistent with respect to prevailing gender stereotypes. To identify the processes underpinning task performance, responses were submitted to a hierarchical drift diffusion model (HDDM) analysis. A consistent pattern of results emerged. Whether manipulated at the level of occupational (Expts. 1, 3, and 5) or trait-based (Expts. 2, 4, and 6) expectancies, stereotypes facilitated task performance and influenced decisional processing via a combination of response and stimulus biases. Specifically, (1) stereotype-consistent stimuli were classified more rapidly than stereotype-inconsistent stimuli; (2) stereotypic responses were favoured over counter-stereotypic responses (i.e., starting-point shift towards stereotypic responses); (3) less evidence was required when responding to stereotypic than counter-stereotypic stimuli (i.e., narrower threshold separation for stereotypic stimuli); and (4) decisional evidence was accumulated more efficiently for stereotype-inconsistent than stereotype-consistent stimuli and when targets had a typical than atypical facial appearance. Collectively, these findings elucidate how stereotypes influence person construal.

Planetary boundaries: Guiding human development on a changing planet

The planetary boundary (PB) concept, introduced in 2009, aimed to define the environmental limits within which humanity can safely operate. This approach has proved influential in global sustainability policy development. Steffen et al. provide an updated and extended analysis of the PB framework. Of the original nine proposed boundaries, they identify three (including climate change) that might push the Earth system into a new state if crossed and that also have a pervasive influence on the remaining boundaries. They also develop the PB framework so that it can be applied usefully in a regional context.

Science , this issue 10.1126/science.1259855

Identifying chemicals that are planetary boundary threats

Rockström et al. proposed a set of planetary boundaries that delimit a "safe operating space for humanity". Many of the planetary boundaries that have so far been identified are determined by chemical agents. Other chemical pollution-related planetary boundaries likely exist, but are currently unknown. A chemical poses an unknown planetary boundary threat if it simultaneously fulfills three conditions: (1) it has an unknown disruptive effect on a vital Earth system process; (2) the disruptive effect is not discovered until it is a problem at the global scale, and (3) the effect is not readily reversible. In this paper, we outline scenarios in which chemicals could fulfill each of the three conditions, then use the scenarios as the basis to define chemical profiles that fit each scenario. The chemical profiles are defined in terms of the nature of the effect of the chemical and the nature of exposure of the environment to the chemical. Prioritization of chemicals in commerce against some of the profiles appears feasible, but there are considerable uncertainties and scientific challenges that must be addressed. Most challenging is prioritizing chemicals for their potential to have a currently unknown effect on a vital Earth system process. We conclude that the most effective strategy currently available to identify chemicals that are planetary boundary threats is prioritization against profiles defined in terms of environmental exposure combined with monitoring and study of the biogeochemical processes that underlie vital Earth system processes to identify currently unknown disruptive effects.

Confronting unknown planetary boundary threats from chemical pollution

Rockström et al. proposed a set of planetary boundaries that delimitate a "safe operating space for humanity". One of the planetary boundaries is determined by "chemical pollution", however no clear definition was provided. Here, we propose that there is no single chemical pollution planetary boundary, but rather that many planetary boundary issues governed by chemical pollution exist. We identify three conditions that must be simultaneously met for chemical pollution to pose a planetary boundary threat. We then discuss approaches to identify chemicals that could fulfill those conditions, and outline a proactive hazard identification strategy that considers long-range transport and the reversibility of chemical pollution.

Computerized venous strain-gauge plethysmography is a reliable method for measuring venous function

OBJECTIVES

To achieve reference values for computerized strain-gauge plethysmography (SGP), to assess reproducibility, and to evaluate the influence of different factors such as age, gender, body mass index, and symptomatic post-thrombotic disease on commonly used variables.

METHODS

Sixty-three healthy controls and 56 patients with previous deep venous thrombosis (DVT) were included. All participants underwent computerized SGP with evaluation of outflow capacity, as well as evaluation of venous reflux and muscle pump function.

RESULTS

All variables were significantly reduced in DVT limbs, both compared with contralateral limbs and with healthy controls. Only two patients had all values within normal ranges (=mean ± 2 SD in controls). Measures of outflow capacity had a coefficient of variation (CV) of 5-6% and exercise-induced volume changes a CV of 10-15%. In symptomatic post-thrombotic limbs half-refilling time was significantly related to presence of edema (R = -0.28, p < .05) and to chronic skin changes (R = -0.58, p < .001).

CONCLUSIONS

We suggest that our values in healthy controls can be used as new reference values for computerized venous strain-gauge plethysmography. The computerized design ensures high reproducibility and the results indicate that this is a very useful and sensitive test for functional quantitative assessment of patients with venous disease.

Deep venous thrombosis after surgery for Achilles tendon rupture: a provoked transient event with minor long-term sequelae

BACKGROUND

Deep venous thrombosis (DVT) occurs frequently in patients undergoing orthopedic surgery, but there is a lack of knowledge regarding long-term sequelae of DVT after different types of surgical procedures.

OBJECTIVE

To describe the long-term effect of symptomatic (SDVT) and asymptomatic (ADVT) deep venous thrombosis on venous function and subsequent incidence of post-thrombotic syndrome (PTS) in patients who have undergone surgery for Achilles tendon rupture.

PATIENTS/METHODS

This observational follow-up study includes 83 patients with postoperative DVT, examined after a mean of 7 years. There were two series of patients: 45 with SDVT and 38 with ADVT. In both series, more than 90% of the DVTs were limited to calf veins. Follow-up examinations comprised color duplex ultrasonography (CDU), strain-gauge plethysmography (SGP), clinical examination including scoring for venous disease and questionnaires for quality of life (QOL).

RESULTS

A mild degree of PTS was found in 11% of the patients: 13% in SDVT and 8% in ADVT patients. The rate of recurrent ipsilateral DVT was 2%. Deep venous reflux was more common in patients with SDVT than in ADVT patients (84% vs. 55%, P < 0.01). Only a few patients had plethysmograpically abnormal findings without difference between the two groups.

CONCLUSION

DVT after surgery for Achilles tendon rupture consists mainly of distal DVTs and are associated with a low risk for PTS. Deep venous reflux was more common in SDVT than in ADVT patients, probably as an effect of larger DVTs in the former group.

Dose and time dependent apoptotic response in a human melanoma cell line exposed to accelerated boron ions at four different LET

The aim was to investigate and compare the influence of linear energy transfer (LET), dose and time on the induction of apoptosis in a human melanoma cell line exposed to accelerated light boron ((10)B) ions and photons. Cells were exposed in vitro to doses up to 6 Gy accelerated boron ions (40, 80, 125 and 160 eV nm(-1)) and up to 12 Gy photons (0.2 eV nm(-1)). The induction of apoptosis was measured up to 9 days after irradiation using morphological characterization of apoptotic cells and bodies. In parallel, measurements of cell-cycle distribution, monitored by DNA flow cytometry, and cell survival based on the clonogenic cell survival assay, were performed. In addition, the induction and repair of DNA double-strand breaks (DSB), using pulsed-field gel electrophoresis (PFGE) were studied. Accelerated boron ions induced a significant increase in apoptosis as compared with photons at all time points studied. At 1-5 h the percentage of radiation-induced apoptotic cells increased with both dose and LET. At the later time points (24-216 h) the apoptotic response was more complex and did not increase in a strictly LET-dependent manner. The early premitotic apoptotic cells disappeared at 24 h following exposure to the highest LET (160 eV nm(-1)). A postmitotic apoptotic response was seen after release of the dose-, time- and LET-dependent G2/M accumulations. The loss of clonogenic ability was dose- and LET-dependent and the fraction of un-rejoined DSB increased with increasing LET. Despite the LET-dependent clonogenic cell killing, it was not possible to measure quantitatively a LET-dependent apoptotic response. This was due to the different time course of appearance and disappearance of apoptotic cells.

Low and high LET radiation‐induced apoptosis in M059J and M059K cells

PURPOSE

To investigate and compare the ability of DNA-dependent protein kinase (DNA-PK)-deficient and -proficient cells to undergo apoptosis after exposure to low and high linear energy transfer (LET) radiation.

MATERIALS AND METHODS

A human glioma cell line M059J lacking the catalytic subunit of DNA-PK (DNA-PKcs) and its DNA-PKcs-proficient counterpart, M059K, were exposed to 1 and 4 Gy of accelerated nitrogen ions (14N, 140 eV nm(-1), 8-12 Gy min(-1)) or 60Co gamma-rays (0.2 eV nm(-1), 0.7 Gy min(-1)). The induction of apoptosis was studied up to 144 h post-irradiation using two different methods: morphological characterization of apoptotic cells after fluorescent staining and cell size distribution analysis to detect apoptotic bodies. In parallel, protein expression of DNA-PKcs and poly(ADP-ribose) polymerase (PARP) as well as DNA-PK and caspase-3 activity were investigated.

RESULTS

Low and high LET radiations (4 Gy) induced a time-dependent apoptotic response in both cell lines. Low LET radiation induced a significantly elevated apoptotic response in M059J as compared with M059K cells at 144 h post-irradiation. Following high LET radiation exposure, there was no difference between the cell lines at this time. PARP cleavage was detected in M059J cells following both low and high LET irradiation, while only high LET radiation induced PARP cleavage in M059K cells. These cleavages occurred in the absence of caspase-3 activation.

CONCLUSIONS

M059J and M059K cells both display radiation-induced apoptosis, which occur independently of caspase-3 activation. The apoptotic course differs between the two cell lines and is dependent on the quality of radiation.

Asymptomatic deep venous thrombosis is associated with a low risk of post-thrombotic syndrome

Post-thrombotic syndrome (PTS) is a well-recognized condition that develops after symptomatic deep venous thrombosis, but the clinical significance and late complications of asymptomatic deep venous thrombosis (ADVT) are unclear.

OBJECTIVE

To determine whether ADVT following minor surgery affects venous function and contributes to the later development of PTS.

PATIENTS/METHODS

The study included 83 patients operated on for Achilles tendon rupture; 38 patients with postoperative ADVT and 45 patients without (control group). The follow-up examinations five years after the operation comprised computerised strain-gauge plethysmography, colour duplex ultrasonography, clinical scoring of venous disease, and quality of life (QOL).

RESULTS

Villalta scores, CEAP classification and QOL did not differ between groups. PTS (=Villalta score > or =5) was found in three ADVT patients (8%) and in two controls (4%). Ultrasonography revealed post-thrombotic changes in 55% of ADVT patients and in none of the controls. Deep venous reflux occurred in 22 ADVT patients and in three controls (P<0.001). There was no difference between groups in plethysmographic variables, demonstrating that the ultrasonographic abnormalities were of negligible haemodynamic significance.

CONCLUSIONS

PTS is not a common sequel to ADVT after minor surgery. Although more than 50% of patients with ADVT developed post-thrombotic changes according to ultrasound, these changes did not result in haemodynamically significant venous dysfunction.

Effect of an ibuprofen-releasing foam dressing on wound pain: a real-life RCT

OBJECTIVE

To compare an ibuprofen-releasing foam dressing (Biatain Ibu, ColoplastA/S) with local best practice in the treatment of painful exuding wounds.

METHOD

In this large-scale randomised comparative study, 853 patients were randomised to either ibuprofen-releasing foam (test) dressing (n=467) or local best practice (n=386). Primary endpoint was wound pain relief from day 1-7, assessed by the patients twice daily using a five-point verbal rating scale. Secondary endpoints were reduction in pain intensity from day 0-7 (assessed using an 11-point numeric box scale), quality of life (assessed using the WHO-5 well-being index and effect on health-related activities of daily living) and the incidence of adverse events.

RESULTS

After seven days significantly more patients in the experimental group experienced relief from temporary and persistent pain and a reduction in pain intensity,when compared with patients in the local best practice group (p<0.0001). They also experienced a greater improvement in quality of life. The number of adverse events in both groups was low.

CONCLUSION

The test dressing provided an appropriate wound healing environment, relieved temporary and persistent wound pain, and decreased pain intensity. It was also associated with an improvement in quality of life.

Primary deep vein thrombosis in the upper limb: A retrospective study with emphasis on pathogenesis and late sequelae

BACKGROUND

Thrombosis of the upper extremity (UEDVT) is an uncommon disease with an incidence of 2-3% of all deep vein thromboses. The aim of this study was to determine the frequency of thrombophilia, post-thrombotic symptoms (PTS), and the rate of complications and recurrences in patients with primary UEDVT, which includes idiopathic and effort-related thrombosis.

METHODS

Thirty-two patients with primary UEDVT were participants in the study. All patients with malignancies and intravenous devices were excluded. Two different scoring instruments - the Villalta and the DASH - were used to diagnose PTS, and a visual analogue scale (VAS) was used to estimate pain and disability. To evaluate working capacity, an arm exercise test was performed. Blood samples were taken for antithrombin, protein C and S deficiencies, antiphospholipid antibodies, mutation of factor V, fibrinogen, D-dimer, and von Willebrand factor antigen.

RESULTS

None of the patients developed malignancy, pulmonary embolism, or recurrent UEDVT. Twenty-eight percent of the patients had mild to moderate PTS according to the scoring instruments. The arm exercise test and the VAS did not provide any additional information about the severity of PTS. The prevalence of thrombophilia was 40%; the most frequent disorders were the mutation of factor V (19%) and elevated fibrinogen (22%).

CONCLUSIONS

This study supports the belief that primary UEDVT is a benign disorder with a low risk for recurrence but with a high frequency of PTS. For a majority of the patients, the underlying cause of the thrombotic event is unclear.

Repairable-conditionally repairable damage model based on dual Poisson processes

The advent of intensity-modulated radiation therapy makes it increasingly important to model the response accurately when large volumes of normal tissues are irradiated by controlled graded dose distributions aimed at maximizing tumor cure and minimizing normal tissue toxicity. The cell survival model proposed here is very useful and flexible for accurate description of the response of healthy tissues as well as tumors in classical and truly radiobiologically optimized radiation therapy. The repairable-conditionally repairable (RCR) model distinguishes between two different types of damage, namely the potentially repairable, which may also be lethal, i.e. if unrepaired or misrepaired, and the conditionally repairable, which may be repaired or may lead to apoptosis if it has not been repaired correctly. When potentially repairable damage is being repaired, for example by nonhomologous end joining, conditionally repairable damage may require in addition a high-fidelity correction by homologous repair. The induction of both types of damage is assumed to be described by Poisson statistics. The resultant cell survival expression has the unique ability to fit most experimental data well at low doses (the initial hypersensitive range), intermediate doses (on the shoulder of the survival curve), and high doses (on the quasi-exponential region of the survival curve). The complete Poisson expression can be approximated well by a simple bi-exponential cell survival expression, S(D) = e(-aD) + bDe(-cD), where the first term describes the survival of undamaged cells and the last term represents survival after complete repair of sublethal damage. The bi-exponential expression makes it easy to derive D(0), D(q), n and alpha, beta values to facilitate comparison with classical cell survival models.

Relative biological effectiveness of boron ions on human melanoma cells

PURPOSE

To compare the difference in relative biological effectiveness (RBE) between (10)B ions and a (60)Co gamma-ray beam for human melanoma cells using in vitro cell survival based on a clonogenic assay.

MATERIALS AND METHODS

Cells were irradiated in vitro under aerobic conditions with (60)Co and (10)B ions with different linear energy transfer (LET) (40, 80 and 160 eV nm(-1)). The dose to the cells was determined using ferrous sulphate dosimetry and an ionisation chamber. The standard linear-quadratic model and the newly proposed repairable conditionally repairable damage (RCR) model were used to calculate the RBE.

RESULTS

The RBE at 10% cell survival for 40, 80 and 160 eV nm(-1) boron ions compared with (60)Co were 1.98 (1.83-2.22), 2.85 (2.64-3.11) and 3.37 (3.17-3.58), respectively, of almost independence of the model used in the calculation.

CONCLUSIONS

Different cell survival models may generate different RBE, especially at low doses and high cell survival levels.

RBE of 50 MV scanned bremsstrahlung beams determined using clonogenic assay

PURPOSE

In order to compare the biological effectiveness of a 50 MV scanned bremsstrahlung beam to (60)Co and 6 MV photons, the survival of Chinese hamster cells (V79-379A), human normal fibroblasts cells (GSH(+/+)) and human small cell lung cancer cells (U-1690) were analysed.

MATERIALS AND METHODS

Cells were irradiated in vitro under aerobic conditions in a plastic phantom. Dose to the cells was determined using ferrous sulphate and ionization chamber dosimetry. A number of cell survival models were fitted to the experimental data, including the standard LQ model with and without the induced repair. In particular, a new model treating damage and repair separately was used in combination with a new technique for accurate RBE determination.

RESULTS

The measured RBE for the three cell lines were 0.988 (0.984-0.992), 0.999 (0.996-1.002) and 1.013 (1.009-1.016) for V79-379A, GSH(+/+) and U-1690 respectively and thus 50 MV scanned beams did not differ more than a fraction of a per cent from conventional therapy beams.

CONCLUSIONS

The present study gives RBE consistent with previously calculated RBEs based on photonuclear reaction cross-sections of high-energy photons.

Contact allergy to hydrocortisone and systemic contact dermatitis from prednisolone with tolerance of betamethasone

BACKGROUND

Contact allergy to corticosteroids is not uncommon. As the clinical pattern that the patients exhibit may be misleading, the discovery at patch testing may be unexpected and solely a result of the fact that marker molecules for corticosteroid contact allergy are incorporated into standard series and that tests are read twice, on D3/4 and D7.

OBJECTIVE

We describe a patient allergic to hydrocortisone who was given a cross-reacting corticosteroid, prednisolone, that led to a systemic contact dermatitis. The patient cleared when betamethasone, a non¿Ncross-reacting corticosteroid, was administered.

METHODS

The patient was patch tested to a standard series including tixocortol pivalate, and an extended corticosteroid series including betamethasone.

RESULTS

Patch testing with tixocortol pivalate provoked an allergic patch test reaction (+? D3, +D7), whereas betamethasone did not.

CONCLUSION

Our patient's allergy was undiagnosed for 5 years, and it was not until she was given a cross-reacting corticosteroid, which led to exacerbation of her dermatitis, that her physician suspected corticosteroid allergy. The incorporation of marker molecules for the detection of corticosteroid contact allergy into standard series with two reading occasions, 3 to 4 days apart, is advocated.

Comparison of the glucose dependency of glucagon-like peptide-1 (7-37) and glyburide in vitro and in vivo

The purpose of the present study was to compare the glucose dependency of the insulin secretagogue activity of the sulfonylurea, glyburide, versus that of glucagon-like peptide-1(7-37) [GLP-1(7-37)] in vitro and in vivo. In freshly isolated rat islets, maximally effective concentrations of glyburide (10 micromol/L) and GLP-1(7-37) (10 nmol/L) were equally effective in stimulating insulin secretion in the presence of 15 mmol/L glucose (2.4-fold increase relative to 15 nmol/L glucose alone). At 5 nmol/L glucose, both agents increased insulin secretion, but the effect for glyburide was threefold greater than for GLP-1(7-37) (122% and 41% increase in insulin secretion, respectively). In conscious catheterized rats infused with glucose at a variable rate to clamp plasma glucose concentration at 11 mmol/L, glyburide (1 mg/kg orally) and GLP -1(7-37) (infused intravenously [IV] at 5 pmol/min/kg) produced similar increase in insulin levels (1.8-fold relative to the respective vehicle controls) that were sustained through 60 minutes of measurement. These doses of GLP-1(7-37) and glyburide were then administered to fasted and fed rats (basal plasma glucose concentration, 5.8 and 7.3 mmol/L, respectively). Relative to the vehicle control group, GLP-1(7-37) infusion produced a transitory increase (30%) in plasma insulin concentration and a modest sustained decrease (10% to 20%) in glucose in both fasted and fed rats, whereas glyburide induced a sustained 2.4- and 1.7-fold increase in plasma insulin concentration in fasted and fed rats, respectively, and a 50% decrease in plasma glucose in both fasted and fed rats. Results of these studies demonstrate the higher glucose threshold for the insulin secretagogue activity of GLP-1(7-37) relative to glyburide in vitro and in vivo.

The antihyperglycemic agent englitazone prevents the defect in glucose transport in rats fed a high-fat diet

The effects of englitazone in male Wistar rats fed a high-fat diet (59% of calories as fat) were compared with control rats fed a high-carbohydrate diet (69% of calories as carbohydrate) (5-15 animals per group). Insulin-stimulated (17 nmol/l) 2-deoxy-D-glucose (2-DG) uptake was inhibited 31% in adipocytes isolated from rats on the high-fat diet for 3 weeks, but englitazone (50 mg/kg for the last 7 days) normalized the response. There was a selective decrease in GLUT4 (54 +/- 5% of high-carbohydrate) in epididymal fat from rats on the high-fat diet for 3 weeks, but englitazone treatment did not reverse the defect in GLUT4 (43 +/- 8% of high-carbohydrate) or increase GLUT1 (81 +/- 12% of high-carbohydrate). Englitazone normalized oral glucose (1 g/kg body wt) intolerance and excessive (210% of high-carbohydrate) liver glycogen deposition (from [14C]glucose) caused by the high-fat diet. The high-fat diet tended to decrease insulin receptor substrate-1 (IRS-1) and phosphatidylinositol-3'-kinase (PI-3-kinase) expression in epididymal fat (26% decrease; P < 0.1). Englitazone did not reverse this decrease in IRS-1 and PI-3-kinase levels in fat from high-fat-fed rats (there was a further 25-30% decrease, P < 0.05), nor did it increase PI-3-kinase activity in 3T3-L1 adipocytes under conditions (48 h incubation) where it stimulated 2-DG uptake sixfold or enhanced insulin-stimulated 2-DG uptake. In summary, englitazone prevented the insulin resistance associated with a high-fat diet, but the mechanism of action does not involve changes in fat or muscle glucose transporter content and may not involve activation of the insulin signaling pathway via PI-3-kinase.

Glucose-dependent action of glucagon-like peptide-1 (7-37) in vivo during short- or long-term administration

In vitro, truncated glucagon-like peptides [GLP-1(7-36)-amide and GLP-1(7-37)] increase insulin secretion in a glucose-dependent manner, and desensitization to the action of GLP-1(7-37) has been demonstrated acutely with high concentrations. The purpose of these studies was to evaluate the glucose dependency and threshold of GLP-1(7-37) action in normal rats and in a rat model of type II diabetes and to assess the effects of long-term administration in vivo. All studies were conducted in conscious catheterized rats. An intravenous (IV) infusion of GLP-1(7-37) at 0.5, 5, or 50 pmol/min/kg during the second hour of a 2-hour 11-mmol/L hyperglycemic clamp in Sprague-Dawley rats produced a dose-related enhancement of the glucose-induced increase in plasma insulin concentration. A 1-hour infusion of a submaximal dose of GLP-1(7-37) (5 pmol/min/kg IV) in fasted and fed Sprague-Dawley rats produced small transient increases in plasma insulin (incremental increases above basal, 72 +/- 27 and 96 +/- 28 pmol/L, respectively) and decreases in plasma glucose (to levels > or = 5.2 mmol/L). Infusion of GLP-1(7-37) (5 pmol/min/kg IV) during a hyperglycemic clamp at two sequentially increasing concentrations of glucose, 11 and 17 mmol/L, produced incremental increases in insulin of 600 and 1,200 pmol/L, respectively, relative to levels in clamped control rats. Similarly, infusion of GLP-1(7-37) (5 pmol/min/kg IV) in hyperinsulinemic, hyperglycemic Zucker diabetic fatty (ZDF) rats produced a transitory increase in plasma insulin concentration and normalized the plasma glucose concentration.(ABSTRACT TRUNCATED AT 250 WORDS)