The quest for GRACE 3.0: improving our beloved risk score with machine learning

Background

Although widely recommended for risk assessment of patients with acute coronary syndrome (ACS), the Global Registry of Acute Coronary Events (GRACE) score famously lacks discriminative power. On the other hand, in-hospital serum hemoglobin levels (HG) have been shown to simultaneously forecast both thrombotic and hemorrhagic hazards.

Purpose

To ascertain the extent to which the incorporation of HG in the GRACE score is able to increase its predictive ability.

Methods

Retrospective single-center study encompassing ACS patients consecutively admitted to a Cardiac Intensive Care Unit. Inclusion criteria comprised the acquaintance of GRACE score, HG and vital status on a 6-month follow-up, which served as the outcome. 3 discriminative models were first created: (standard) GRACE score (model 1); GRACE score plus HG, by means of logistic regression (model 2); GRACE score plus HG, by means of multilayer perceptron (a class of feedforward artificial neural network) (model 3). Hereafter, if models 2 and/or 3 were to be found significantly more discriminative than model 1, a correction factor would be calculated, also allowing for the conception of the most predictive model possible (model 4). The discriminative ability was estimated by both the area under the receiver-operating characteristic curve (AUC), and the dyad sensitivity/specificity.

Results

Between April 2009 and December 2016, 1468 patients met study inclusion criteria. Mean age was 68.0±13.2 years and 29.8% were female, while 36.9% presented with ST-segment elevation myocardial infarction. Mean GRACE score was 145.5±47.0 and mean HG was 13.5±2.0. All-cause mortality reached 10.5%, at 6 months. Predictive power for models 1, 2 and 3 may be quantified as follows: AUC 0.6998, sensitivity 77.7% and specificity 62.5%; AUC 0.7818, sensitivity 36.3% and specificity 92.2%; AUC 0.7851, sensitivity 47.7% and specificity 88.5%, respectively. Both models 2 and 3 exhibited more discriminative ability than model 1 (p<0.001), due to their higher specificity. As such, a correction factor was computed (y = −7.8556x + 86.4117) and model 4 was created, displaying a sensitivity of 65.9% and a specificity of 76.5%.

Conclusion

HG single-handedly provides incremental predictive value – namely more specificity – to the GRACE score. In particular, the latter seems to overestimate ACS patients' risk if HG is normal or close to normal.

Funding Acknowledgement

Type of funding sources: None.

Disfrute a través de una propuesta de descansos activos en educación infantil

La siguiente propuesta muestra un estudio que pretendió comprobar cuál es la influencia que tienen los descansos activos en el disfrute del alumnado de Educación Infantil, siendo este un elemento de la motivación. Además, se evaluó la existencia de diferencias en el disfrute en función del sexo del alumnado. Para ello, se llevó a cabo una metodología basada en los descansos activos durante diez días, en los cuales se recogieron las impresiones del alumnado a través de un test que se pasaba tras la actividad sedentaria, y, de igual forma, tras los descansos activos. Igualmente, se recogieron las impresiones por parte del profesorado a través de una entrevista realizada el último día del estudio. La muestra tomada para este trabajo constaba de 22 sujetos de una clase del primer curso del segundo ciclo de Educación Infantil (3 años), siendo estos 12 niñas y 10 niños. Finalmente, los resultados permitieron concluir que los descansos activos aumentan el disfrute del alumnado, sin que se den diferencias de acuerdo con la variable sexo. 

Protective effect of sulfurous water in peripheral blood mononuclear cells of Alzheimer's disease patients

AIMS

One of the main features of sulfurous water (SW) is the presence of hydrogen sulfide (H2S), which confers its antioxidant activity. Since oxidative stress plays an important role in Alzheimer's disease (AD) we hypothesize that SW could have a protective effect in these patients.

MATERIAL AND METHODS

A therapeutic in vitro approach of SW was performed in peripheral blood mononuclear cells (PBMCs) of AD patients and in age-matched healthy non-demented controls using one modification of the comet assay (to measure oxidative DNA damage) and the MTT assay (as an indicator of cell viability). Hydrogen peroxide and homocysteine were used to induce oxidative DNA damage, and vitamin C, Trolox and N-acetyl-cysteine were selected as antioxidants of reference to compare SW treatment results.

KEY FINDINGS

SW did not increase per se the oxidative DNA damage of PBMC. Furthermore, SW protected them against enhanced oxidative stress in AD and control populations after pro-oxidant stimuli, with similar results to those observed when using the antioxidants of reference. Nevertheless, SW was the only treatment that could avoid the loss of viability of PBMC for all pro-oxidant stimuli in both populations, suggesting that H2S could confer to SW a more antioxidant capacity than other known antioxidants.

SIGNIFICANCE

The protective effect of SW was proved for the first time not only in DNA stability but also in cell viability preservation in AD, indicating that further research in other in vitro and in vivo models could lead to include SW as a possible therapy for AD.

Effect of elite physical exercise by triathletes on seven catabolites of DNA oxidation

The oxidized nucleoside 8-hydroxy-2'-deoxyguanosine has been widely studied as a marker of DNA oxidation; however, data on the occurrence of other metabolites in plasma that are related to DNA damage are scarce. We have applied an improved, sensitive, robust, and reliable method, involving solid phase extraction and ultrahigh-performance liquid chromatography (UHPLC)-tandem mass spectrometry (MS/MS), to the precise quantitation of seven metabolites in the plasma of 15 elite triathletes after a 2-week training program. All compounds were eluted in the first 1.6 min, with limits of detection and quantification ranging between 0.001 and 0.3 ng.mL(-1) and 0.009 and 0.6 ng.mL(-1), respectively. Four compounds were detected in plasma: guanosine-3'-5'-cyclic monophosphate, 8-hydroxyguanine, 8-hydroxy-2'-deoxyguanosine, and 8-nitroguanosine. After two weeks of training, 8-hydroxyguanine exhibited the highest increase (from 0.031 ± 0.008 nM to 0.036 ± 0.012 nM) (p < 0.05), which could be related to the enhanced activity of DNA-repairing enzymes that excise this oxidized base. Increased levels of guanosine-3'-5'-cyclic monophosphate and 8-hydroxy-2'-deoxyguanosine were also observed. In contrast, levels of 8-nitroguanosine (p < 0.05) were significantly reduced, which might be a protective measure as this compound strongly stimulates the generation of superoxide radicals, and its excess is related to pathologies such as microbial (viral) infections and other inflammatory and degenerative disorders. The results obtained indicate an induced adaptive response to the increased oxidative stress related to elite training, and point to the benefits associated with regular exercise.

Expression of the basophil-specific antibodies 2D7 and BB1 in patients with cutaneous Mastocytosis

BACKGROUND

2D7 and BB1 are thought to be basophil-specific markers. In this study, we tested both antibodies in different skin and mast cell disorders with the aim of determining whether it was possible to differentiate between benign and aggressive presentations of mastocytosis.

METHODS

Using the antibodies 2D7, BB1, and c-Kit, we performed an immunohistochemical study of skin biopsy specimens from patients with cutaneous mastocytosis (15 urticaria pigmentosa and telangiectatic macularis eruptive perstans) and liver or bone marrow biopsy specimens from patients with systemic mastocytosis. A basophil leukemia cell line was used as a reference. Peripheral blood basophils from healthy donors were used as controls.

RESULTS

We observed intense expression of 2D7 and BB1 in all skin biopsy specimens from patients with cutaneous mastocytosis. Immunostaining of liver and bone marrow specimens from patients with systemic mastocytosis with 2D7 and BB1 antibodies was negative. Specimens from patients with either type of mastocytosis showed similarly strong expression of c-Kit. The basophil cell line showed a 2D7 and a BB1 profile, with intense expression of c-Kit. Peripheral blood basophils exhibited notable immunostaining for 2D7, BB1, and c-Kit.

CONCLUSIONS

2D7 and BB1 are expressed in cutaneous mastocytosis, although this expression is lost when mast cell proliferation is systemic, thus reflecting either a different cellular differentiation stage or the presence of basophils in these skin diseases.

Avian influenza and Newcastle disease in three risk areas for H5N1 highly pathogenic avian influenza in Mali, 2007-2008

Our survey aimed to investigate avian influenza (AI) and Newcastle disease (ND) prevalence and risk factors in three areas of Mali at risk for occurrence of H5N1 highly pathogenic avian influenza. Blood samples and cloacal and oropharyngeal swabs were collected from 1470 birds between February 2007 and May 2008 and were tested by commercial enzyme-linked immunosorbent assay to detect antibodies and real-time reverse-transcription (rRT)-PCR to detect virus. Risk factors associated with seropositivity or positive rRT-PCR were identified by random effect logistic regression. AI seroprevalence was significantly lower in birds from commercial farms (0%) than in village backyard birds (3.1%). For backyard birds, no individual risk factors (species, age, sex) were identified, but birds in the Mopti area in the Sahelian zone, where millions of wild birds migrate, were more seropositive than in the Sikasso area in the Sudano-Guinean zone (odds ratio [OR] = 2.0, P = 0.051). Among backyard birds nonvaccinated against ND, ND seroprevalence was 58.4%, and the odds of seropositivity was 2.0 higher in chickens than in ducks, 1.7 higher in females than in males, 3.1 higher in adults than in young birds, and 3.0 higher in poultry from the Sikasso area than from the Mopti area (P < 0.01 in all cases). Prevalence established by rRT-PCR was low for both AI virus (1.1%) and ND virus (2.6%) and was associated with no risk factors for AI but was higher in chickens than in ducks (OR = 5.3, P = 0.05) and in the Sikasso area than in the Mopti area (OR = 3.4, P = 0.027) for ND. For AI and ND, prevalence assessed by serology or rRT-PCR varied over time, although seasonal and interannual variation could not be clearly distinguished. The intracluster correlation coefficient for serologic data was low for AI (0.014) and higher for ND (0.222). These results are useful to optimize surveillance and control strategy for notifiable avian diseases in African countries with similar agroecological and resource-limited contexts.

Risk factors for avian influenza and Newcastle disease in smallholder farming systems, Madagascar highlands

Newcastle disease (ND) and avian influenza (AI) are issues of interest to avian producers in Madagascar. Newcastle disease virus (NDV) is the major constraint for village aviculture, and avian influenza viruses type A (AIAV) are known to circulate in bird flocks. This study aims at classifying smallholder poultry farms, according to the combination of risk factors potentially associated with NDV and AIAV transmission and to assess the level of infection for each farm class. Two study sites, Lake Alaotra and Grand Antananarivo, were chosen with respect to their differences in terms of agro-ecological features and poultry productions. A typology survey involving 526 farms was performed to identify possible risk factors for (i) within-village, and (ii) between-village virus transmission. A cross-sectional serological study was also carried out in 270 farms to assess sero-prevalences of NDV and AIAV for each farm class and the link between them and risk factor patterns. For within-village transmission, four classes of farms were identified in Grand Antananarivo and five in Lake Alaotra. For between-village virus transmission, four classes of farms were identified for each site. In both sites, NDV sero-prevalence was higher than for AIAV. There was no evidence of the presence of H5 or H7 subtypes of AIAV. Sero-prevalences were significantly higher in Lake Alaotra than in Grand Antananarivo for both viruses (OR=2.4, p=0.02 for NDV, and OR=9.6, p<0.0001 for AIAV). For within-village NDV transmission in Grand Antananarivo, backyard chicken farms (OR=3.6, p<0.001), and chicken farms with biosecurity awareness (OR=3.4, p<0.01) had greater odds of having antibodies against NDV than the others. For between-village virus transmission, farms with multiple external contacts, and farms using many small markets had greater odds of having antibodies against NDV than the others (OR=5.4, p<0.01). For AIAV, there were no differences in sero-prevalences among farm classes. In Lake Alaotra, the observed high density of palmipeds and widespread rice paddies were associated with high sero-prevalences for both viruses, and a homogeneous risk of virus transmission between the different farm classes. In Grand Antananarivo, farm visits by collectors or animal health workers, and farm contacts with several markets were identified as potential risk factors for NDV transmission. Further studies are needed to identify the circulating virus genotypes, model their transmission risk, and provide adapted control measures.

Understanding the ecological drivers of avian influenza virus infection in wildfowl: a continental-scale study across Africa

Despite considerable effort for surveillance of wild birds for avian influenza viruses (AIVs), empirical investigations of ecological drivers of AIV prevalence in wild birds are still scarce. Here we used a continental-scale dataset, collected in tropical wetlands of 15 African countries, to test the relative roles of a range of ecological factors on patterns of AIV prevalence in wildfowl. Seasonal and geographical variations in prevalence were positively related to the local density of the wildfowl community and to the wintering period of Eurasian migratory birds in Africa. The predominant influence of wildfowl density with no influence of climatic conditions suggests, in contrast to temperate regions, a predominant role for inter-individual transmission rather than transmission via long-lived virus persisting in the environment. Higher prevalences were found in Anas species than in non-Anas species even when we account for differences in their foraging behaviour (primarily dabbling or not) or their geographical origin (Eurasian or Afro-tropical), suggesting the existence of intrinsic differences between wildfowl taxonomic groups in receptivity to infection. Birds were found infected as often in oropharyngeal as in cloacal samples, but rarely for both types of sample concurrently, indicating that both respiratory and digestive tracts may be important for AIV replication.

Influence of memory strategies on memory test performance: a study in healthy and pathological aging

The ability to generate memory strategies is a key factor in the performance of episodic memory tasks. Whether the ability to generate memory strategies exerts an influence in the performance of memory tests in the elderly population is still a matter of debate. Here we present results from an experimental memory task (Test of Memory Strategies, TMS), comprised of five lists of words starting from an incidental learning task, and four more lists which progressively gain in their external organization of the material, reducing the necessity of mobilizing complex memory strategies. TMS has been applied to four groups of elderly patients (amnestic Mild Cognitive Impairment - aMCI, multidomain (mMCI), and Vascular Cognitive Impairment - VCI and Depression) and a healthy aging group. In conditions with low organization of the material, the mMCI and VCI groups (both showing a greater executive function impairment) have shown lower performance. However, as the material was progressively organized, they improved their performance. The aMCI group showed similar performance to the control group at the lower level of external organization but did not improve performance in conditions with a high level of external organization. The mMCI and VCI groups showed lower performance on all TMS conditions compared with controls. Discriminant analysis revealed 90% sensitivity and specificity to differentiate between groups based on TMS conditions. These results indicate how executive functions influence performance on memory tasks in elderly subjects with different neuropsychological profiles.

Safety of positive-pressure valve connectors in arterial catheters inserted into critically ill patients

Needleless valve connectors were introduced to avoid needlestick injuries in healthcare workers but some concerns exist about their microbiological safety. A randomised controlled trial was performed to assess hub colonisation affecting positive-pressure valve connectors (PPVCs) compared to conventional caps used for radial arterial catheters inserted into critically ill patients. Patients were randomly assigned either to the PPVC (Smartsite Plus positive bolus valve) or to the conventional cap group. Only catheters inserted for >24h were analysed. Of 100 consecutive arterial lines, 80 were inserted for >24h (mean insertion duration 5.8 days), 41 in the PPVC group and 39 in the conventional cap group. Catheter hubs were colonised in eight cases in the control group (20.5%) and in one case in the PPVC group (2.4%). Hub colonisation was caused by coagulase-negative staphylococci in all cases. No attributable bacteraemia was observed. In multivariate analysis, PPVC (odds ratio: 0.09; 95% confidence interval: 0.1-0.79; P=0.03) and use of the line for continuous haemodynamic monitoring (0.16; 0.03-0.89; P=0.037) were independently associated with a lower incidence of hub colonisation.

Ventricular arrhythmias assessment

An integrated framework for ventricular arrhythmias (VA) assessment, composed of two levels, is proposed in this work. The first level consists of four independent neural networks (NN), designed for specific detection tasks: signal quality, premature ventricular contractions (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF). Time and frequency domain features, obtained from the electrocardiogram (ECG) and selected through a correlation analysis procedure, form the inputs to the neural modules. The outputs feed the second layer, which consists of a global classifier (ANFIS structure), returns the global result for the VA assessment scheme. Sensitivity and specificity values, evaluated from public MIT-BIH databases, show the effectiveness of the proposed strategy.

Long-term storage at tropical temperature of dried-blood filter papers for detection and genotyping of RNA and DNA viruses by direct PCR

In tropical countries the diagnosis of viral infections of humans or animals is often hampered by the lack of suitable clinical material and the necessity to maintain a cold chain for sample preservation up to the laboratory. This study describes the use of filter papers for rapid sample collection, and the molecular detection and genotyping of viruses when stored over long periods at elevated temperatures. Infected blood was collected on filter papers, dried and stored at different temperatures (22, 32 and 37 degrees C) for various periods (up to 9 months). Two animal viruses, African swine fever, a large double-stranded DNA virus and Peste des Petits Ruminants, a negative single-stranded RNA virus, were used to validate the method. Filter papers with dried blood containing virus or control plasmid DNA were cut in small 5mm(2) pieces and added directly to the PCR tube for conventional PCR. Nucleic acid from both viruses could still be detected after 3 months at 32 degrees C. Moreover, the DNA virus could be detected at least 9 months after conservation at 37 degrees C. PCR products obtained from the filter papers were sequenced and phylogenetic analysis carried out. The results were consistent with published sequences, demonstrating that this method can be used for virus genotyping.

Infections of implantable cardioverter-defibrillators: frequency, predisposing factors and clinical significance

The prognosis for patients with ventricular arrhythmias has improved dramatically with the aid of implantable cardioverter-defibrillators (ICDs). Although infection is a serious complication that frequently causes dysfunction and loss of ICDs, the frequency, predisposing risk-factors, and clinical and microbiological features are only partially understood. This study describes a retrospective review of 423 procedures in 278 patients with ICD primary implants and replacements performed at a tertiary-care hospital. Generators were placed in either a pectoral (68%) or abdominal (32%) site, and electrodes were placed transvenously in 97% of the patients. Most (95%) interventions were performed in a one-stage procedure. Infection developed with ten (2.4%) implanted devices. Four cases occurred within 30 days of surgery ('early infections') and six occurred > 1 month after surgery ('late infections'). In univariate analysis, factors associated with the development of an early infection were: two-stage surgery, a sub-costal approach, and abdominal generator placement. In patients with late infections, a significant association was found with trauma or decubitus ulcer in the generator area. Infection presented with local signs without systemic complications. Seven of the ten patients required complete removal of the system.

Successful treatment of lichen planus with sulfasalazine in 20 patients

BACKGROUND

Lichen planus (LP) is a disturbing pruritic cutaneous disease that may have an spontaneous resolution or exhibit a more chronic course during some weeks or months.

OBJECTIVE

Our objective was to demonstrate that sulfasalazine is effective in the treatment of LP.

METHODS

Twenty patients were diagnosed in our department with LP of the skin and/or mucosa between 1985 and 2001 on the basis of clinical and histologic findings.

RESULTS

All patients were treated with sulfasalzine at initial doses of 1.5 g/day, increasing by 0.5 g/week to 3 g/day for 4-16 weeks. Some patients also received descendent doses for 2-12 months. Complete responses were observed in 13 patients and partial responses in seven patients. All patients reported an early resolution of the pruritus. No changes were detected in mucosal LP. Most of the patients tolerated the treatment well and only eight patients presented some minor side-effects.

CONCLUSION

Sulfasalazine is a successful therapeutic option for cutaneous LP, constituting an alternative to corticosteroids and retinoids.

[Antioxidant enzymes in acute cerebral infarction]

BACKGROUND AND PURPOSE

Oxidative modification of DNA, protein and lipids by reactive oxygen peroxides plays an important role in acute cerebral infarction. The biological antioxidant defence system against oxidative stress is an integrated array of enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathion peroxidase (GPx). The purpose of this work was: 1. To investigate the evolution of SOD and CAT activities as possible markers of oxidative activity in patients with acute cerebral infarction. 2. To establish the relationship between the type of stroke and the activity of these two enzymes. 3. To analyze the relationship between the degree of neurological deficits of patients with stroke and SOD and CAT activities.

PATIENTS AND METHODS

This is a prospective study comprising 45 patients with acute cerebral infarction (24 females and 21 males), aged from 48 to 96. The infarcts were classified in atherotrombotics and cardioembolics. SOD and CAT activities were measured on days 1, 3, 6 and 15.

RESULTS

Activities of SOD and CAT in patients on admission were lower than those of controls and showed a gradual increase over time. The activity mean of SOD was significantly higher in cardioembolic infarctions than in atherotrombotic infarctions (p < 0.05). SOD activity was significantly lower for Mathew score > 60, while CAT activity was higher.

CONCLUSIONS

Our findings suggest that there is a progressive increase in SOD and CAT activity during ictus evolution, a different activity of SOD and CAT in cardioembolic and atherotrombotic infarctions, and that there is a relationship between activity of antioxidant enzymes and Mathew's score.

Significance of protein p53 overexpression in the clinical course of high-risk superficial bladder cancer

OBJECTIVES

This is a retrospective study in which the long-term biological behavior of 67 "high-risk" superficial bladder tumors and the prognostic relevance (prediction of disease recurrence and progression) of the determination of the p53 phenotype in these cases were studied.

MATERIAL AND METHODS

67 tumors with a "high-risk" of progression were selected from the 1,103 transurethral resections for bladder cancer carried out in 640 patients in this center between 1987 and 1992. These included 39 T1G3, 14 Tis (isolated or associated with Ta-T1, non-G3 tumors), and 14 Ta-T1, non-G3 tumors with submucosal lymphatic affection (L+). The median follow-up of these cases was 69.7 months. An immunohistochemical technique with monoclonal antibodies (DO-7) was used to detect the p53 phenotype in paraffin-fixed material.

RESULTS

Tumor recurrence occurred in 31 patients (46.3%) and local or distant progression in 14 (20.9%). Radical cystectomy was carried out in 16 (23.9%) cases. p53 overexpression of > or =20% ("p53+") was detected in 40 tumors (59.7%). The rate of recurrence and progression, the disease and progression-free intervals, cancer-specific survival, disease-free survival and progression-free survival were similar in the 3 tumor groups (in all cases, p > 0.05). There were no significant differences in the overexpression of protein p53, using the standard cutoff point of 20% stained nuclei, on comparing the same variables in the whole group of 67 patients (in all cases, p > 0.05).

CONCLUSION

The detection of protein p53 was not found to be of use in the retrospective prediction of disease progression or survival in "high-risk" superficial bladder cancer.

The use of neural networks and logistic regression analysis for predicting pathological stage in men undergoing radical prostatectomy: a population based study

PURPOSE

Clinical under staging occurs in 40% to 60% of patients who undergo radical prostatectomy for prostate cancer. To decrease under staging several methods of predicting pathological stage preoperatively have been developed based on statistical logistic regression analysis and neural networks. To our knowledge none has been validated in our homogeneous regional patient population to date. We created logistic regression and neural network models, and implemented and adapted them into our practice. We also compared the 2 methods to determine their value and practicality in daily clinical practice. We present the results of our novel approach for predicting pathological staging of prostate adenocarcinoma.

MATERIALS AND METHODS

Between 1986 and 1999, 600 white men from the Aragon region of Spain underwent surgery for prostate cancer; of whom 468 were selected for study. Predictive study variables included patient age, clinical stage, biopsy Gleason score and preoperative prostate specific antigen (PSA). The predicted result included in analysis was organ confined or nonorgan confined disease. Data were analyzed by multivariate logistic regression and a supervised neural network (multilayer perceptron and radial basis function). Results were compared by comparing the areas under the receiver operating characteristics curves.

RESULTS

We generated 5 logistic regression models. The model created with clinical staging, Gleason biopsy score and PSA distributed in 5 categories (p <0.001) with an area under the receiver operating characteristics curve of 0.840 proved to be most predictive of pathological stage. Similarly of the 6 neural network models evaluated the radial basis function model, which included age, clinical stage, Gleason biopsy score and preoperative PSA distributed in 5 categories with an area under the curve of 0.882, proved the most predictive but not superior to the logistic regression model. The difference in the area under the curves in the 2 chosen models was 0.042 (p = 0.1).

CONCLUSIONS

It is possible to generate useful predictive models of organ confined disease using logistic regression or neural networks with high indexes of clinical and statistical validity. However, using these variables neural networks did not prove to be better than logistic regression analysis. Therefore, better predictive variables must be identified, preferably nonlinear characteristics with respect to the probability of organ confined tumor, to generate better predictive models using neural networks.

Sonography in acute appendicitis: diagnostic utility and influence upon management and outcome

A study is made of the diagnostic utility of echography in clinically suspected appendicitis, and its influence upon patient management and outcome. A total of 374 consecutive patients with possible appendicitis were prospectively evaluated by ultrasound. Two groups were established: group A (high clinical probability, > or =0.70) and group B (moderate clinical probability, 0.20-0.60). In group-A patients (n = 105, 28%), prevalence of appendicitis = 0.90) underwent surgery regardless of the echographic findings. In group B (n = 269, 72%), prevalence of appendicitis = 0.28) surgery was performed in the event of positive echography, whereas negative echographic findings did not definitively discard appendicitis. The diagnostic utility of echography was evaluated by applying the Pauker-Kasirer threshold approach to clinical decision making. The influence of ultrasound upon outcome was in turn evaluated by contrasting the total appendectomized patients (190 of 374) with a series of 181 individuals subjected to appendectomy prior to the introduction of echography. The probability of appendicitis in the presence of positive echography was 0.95 in group A (sensitivity = 0.92) and 0.89 in group B (sensitivity = 0.91). The probability of appendicitis in the event of negative ultrasound was 0.58 in group A (specificity = 0.55) and 0.03 in group B (specificity = 0.95) . In 46% of cases the echographic findings led to a change in therapeutic regimen. In addition, the incidence of negative appendectomies was significantly reduced (19.3 vs 11.6% with echography; p = 0.03), as was the delay in establishing a diagnosis (under 6 h in 68.5 vs 84.2% with echography; p = 0.002) and the number of medical acts required (three in 71.3 vs 84.1% with echography; p = 0.001). There was no significant reduction in the incidence of perforated appendicitis (17.1 vs 17.9% with echography), in the number of postoperative complications (13.8 vs 7.6% with echography), or in the days of hospital stay (4.44 vs 4.80 with echography). Echography proved useful in group B, and was generally of little utility in group A. The technique had a positive influence on treatment, with management reorientation in a considerable number of patients, and on outcome, since ultrasound contributed to establishing an earlier diagnosis, with a reduction of unnecessary appendectomies.

BIG: a calossin-like protein required for polar auxin transport in Arabidopsis

Polar auxin transport is crucial for the regulation of auxin action and required for some light-regulated responses during plant development. We have found that two mutants of Arabidopsis-doc1, which displays altered expression of light-regulated genes, and tir3, known for its reduced auxin transport-have similar defects and define mutations in a single gene that we have renamed BIG. BIG is very similar to the Drosophila gene Calossin/Pushover, a member of a gene family also present in Caenorhabditis elegans and human genomes. The protein encoded by BIG is extraordinary in size, 560 kD, and contains several putative Zn-finger domains. Expression-profiling experiments indicate that altered expression of multiple light-regulated genes in doc1 mutants can be suppressed by elevated levels of auxin caused by overexpression of an auxin biosynthetic gene, suggesting that normal auxin distribution is required to maintain low-level expression of these genes in the dark. Double mutants of tir3 with the auxin mutants pin1, pid, and axr1 display severe defects in auxin-dependent growth of the inflorescence. Chemical inhibitors of auxin transport change the intracellular localization of the auxin efflux carrier PIN1 in doc1/tir3 mutants, supporting the idea that BIG is required for normal auxin efflux.

Gastrointestinal bezoars: sonographic and CT characteristics

OBJECTIVE

The purpose of this study was to assess the value of imaging studies--conventional abdominal radiographs, sonography, and CT--in the diagnosis of gastrointestinal bezoars.

METHODS AND METHODS

A review was made of the radiologic findings of 17 consecutive patients with surgically verified gastrointestinal bezoars over a period of 51 months.

RESULTS

Twelve patients had a history of previous gastric surgery. In no patient was a bezoar clinically suspected. Phytobezoars were recorded in 16 patients and a trichobezoar in only one. A total of 33 bezoars were identified at surgery. Two patients had isolated gastric bezoars, whereas 15 patients had bezoars located in the small bowel. Among the latter group, associated gastric bezoars were found in eight patients, and five patients had multiple intestinal bezoars. Abdominal radiographs revealed bezoars in three patients, sonography revealed bezoars in 15, and CT revealed bezoars in all 17. Seven patients had associated gastric bezoars revealed at CT versus only two patients with gastric bezoars revealed at sonography. CT revealed multiple intestinal bezoars in five patients whereas sonography revealed them in only two patients.

CONCLUSION

Both sonography and CT are reliable methods for diagnosing gastrointestinal bezoars. CT is more accurate, however, and exhibits a quite characteristic bezoar image; in addition, this imaging technique is able to reveal the presence of additional gastrointestinal bezoars.