A simple methodology for characterization of germanium coaxial detectors by using Monte Carlo simulation and evolutionary algorithms

The determination in a sample of the activity concentration of a specific radionuclide by gamma spectrometry needs to know the full energy peak efficiency (FEPE) for the energy of interest. The difficulties related to the experimental calibration make it advisable to have alternative methods for FEPE determination, such as the simulation of the transport of photons in the crystal by the Monte Carlo method, which requires an accurate knowledge of the characteristics and geometry of the detector. The characterization process is mainly carried out by Canberra Industries Inc. using proprietary techniques and methodologies developed by that company. It is a costly procedure (due to shipping and to the cost of the process itself) and for some research laboratories an alternative in situ procedure can be very useful. The main goal of this paper is to find an alternative to this costly characterization process, by establishing a method for optimizing the parameters of characterizing the detector, through a computational procedure which could be reproduced at a standard research lab. This method consists in the determination of the detector geometric parameters by using Monte Carlo simulation in parallel with an optimization process, based on evolutionary algorithms, starting from a set of reference FEPEs determined experimentally or computationally. The proposed method has proven to be effective and simple to implement. It provides a set of characterization parameters which it has been successfully validated for different source-detector geometries, and also for a wide range of environmental samples and certified materials.

Microscopic properties of xenon plasmas for density and temperature regimes of laboratory astrophysics experiments on radiative shocks

This work is divided into two parts. In the first one, a study of radiative properties (such as monochromatic and the Rosseland and Planck mean opacities, monochromatic emissivities, and radiative power loss) and of the average ionization and charge state distribution of xenon plasmas in a range of plasma conditions of interest in laboratory astrophysics and extreme ultraviolet lithography is performed. We have made a particular emphasis in the analysis of the validity of the assumption of local thermodynamic equilibrium and the influence of the atomic description in the calculation of the radiative properties. Using the results obtained in this study, in the second part of the work we have analyzed a radiative shock that propagated in xenon generated in an experiment carried out at the Prague Asterix Laser System. In particular, we have addressed the effect of plasma self-absorption in the radiative precursor, the influence of the radiation emitted from the shocked shell and the plasma self-emission in the radiative precursor, the cooling time in the cooling layer, and the possibility of thermal instabilities in the postshock region.

Measurement of the transverse target and beam-target asymmetries in η meson photoproduction at MAMI

We present new data for the transverse target asymmetry T and the very first data for the beam-target asymmetry F in the γ[over →]p[over →]→ηp reaction up to a center-of-mass energy of W=1.9  GeV. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. All existing model predictions fail to reproduce the new data indicating a significant impact on our understanding of the underlying dynamics of η meson photoproduction. The peculiar nodal structure observed in existing T data close to threshold is not confirmed.

Natural radioactivity measurements of beach sands in Gran Canaria, Canary Islands (Spain)

Concentrations of natural radionuclides (226)Ra, (232)Th, (40)K and man-made (137)Cs in most important tourist Gran Canaria beaches have been determined using a high-purity Germanium detector to analyse their radiological hazard. Average values of the activity concentrations of (226)Ra, (232)Th and (40)K were 17.6±1.4, 21.3±1.8 and 480±22 Bq kg(-1), respectively. Observed activity concentration values of (137)Cs were practically negligible from a radiological protection point of view. The results of this paper were compared with others published in the bibliography for beaches and coastal sediments of different countries. The mean external air absorbed dose rate was 43.9±2.8 nGyh(-1), which resulted in an outdoor annual effective dose below the world average. Also, the radium equivalent and the external hazard index were calculated. Results from Gran Canaria beaches showed the low levels of radioactivity, indicating no significant radiological risk related to human activities in the area.

New Measurement of the π0 radiative decay width

High precision measurements of the differential cross sections for π0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the π0→γγ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The π0→γγ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0→γγ)=7.82±0.14(stat)±0.17(syst)  eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.

Feasibility of Sentinel Lymph Node Biopsy in Multiple Unilateral Synchronous Breast Cancer: Results of a French Prospective Multi-Institutional Study (IGASSU 0502)

Introduction: Controversy remains over whether to perform sentinel lymph node biopsy (SLNB) in multiple (multicentric or multifocal) unilateral synchronous breast cancer. Several small retro- or prospective studies, included pre- or post-operative (or both) multiple synchronous tumours (MST) have suggested that the test performance of SLNB is similar to that seen in unifocal disease. The purpose of this study was to evaluate the feasibility and accuracy of SLNB in preoperatively diagnosed invasive MST.Patients and Methods: The Interest of Axillary SLNB in Multiple Invasive Breast Cancer (IGASSU) study was a prospective multi-institutional study with initial breast surgery, SLNB, and systematic level I to II axillary lymph node dissection (ALND). Patients eligible for the IGASSU study had an operable invasive MST, defined as two or more physically separate invasive tumours in the same or different breast quadrant. The diagnosis of invasive MST was confirmed histologically in all patients by core needle biopsy before surgery. Detection of sentinel node was performed by using either blue patent or radiocolloide injection or both. Injection sites were subareolar.Statistical Analysis: Sensitivity (Se), negative predictive value (NPV), accuracy (A), false negative rate (FNR) and their 95%-confidence intervals (95%CI) were calculated with a classical 2x2 contingency table. A univariate analysis using odds ratio calculation was performed to identify the risk factors for false negative results.Results: Between March 1, 2006, and August 31, 2007, 216 patients were prospectively included from 16 institutions. Of these patients, 211 were evaluable. The SLNB identified rate were 93.4% (197/211). A mean number of 2.2 SLN (range, 1 to 8, ± 1.4) was successfully excised. The mean number of resected nodes in ALND was 12 (range, 1 to 39, ± 5.7). The FNR was 13.6% (14/103) [95%CI: 7- 20%], Se was 86 .4% (89/103) [95%CI: 79- 93%], NPV was 87% (94/108) [95%CI: 80-93%], A was 92.9% (183/197) [95%CI: 89- 96%]. For the 14 false-negative SN, all had ≤ 3 involved nodes in ALND. Table 1 shows patterns of management of the axilla.Table 1 ALND+ALND-Non-identified SLNB113Identified SLNB+4544Identified SLNB-1494 In a univariate analysis, tumour location (only external location vs other location) was the only clinico-pathological factor influencing the FNR (22% [11-33%] vs 7% [4-10%]), even then median aggregate histological tumour size was smaller in external tumours (17mm [range, 12-80] vs 34mm [range, 8- 90], p=0.016).Conclusion: With a FNR of 13.6% (95%CI: 7-20%), we do not recommend SLNB as a routine procedure for multiple unilateral synchronous breast cancer, even for small tumour foci.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 305.

Modeling of population kinetics of plasmas that are not in local thermodynamic equilibrium, using a versatile collisional-radiative model based on analytical rates

We discuss the modeling of population kinetics of nonequilibrium steady-state plasmas using a collisional-radiative model and code based on analytical rates (ABAKO). ABAKO can be applied to low-to-high Z ions for a wide range of laboratory plasma conditions: coronal, local thermodynamic equilibrium or nonlocal thermodynamic equilibrium, and optically thin or thick plasmas. ABAKO combines a set of analytical approximations to atomic rates, which yield substantial savings in computer running time, still comparing well with more elaborate codes and experimental data. A simple approximation to calculate the electron capture cross section in terms of the collisional excitation cross section has been adapted to work in a detailed-configuration-accounting approach, thus allowing autoionizing states to be explicitly included in the kinetics in a fast and efficient way. Radiation transport effects in the atomic kinetics due to line trapping in the plasma are taken into account via geometry-dependent escape factors. Since the kinetics problem often involves very large sparse matrices, an iterative method is used to perform the matrix inversion. In order to illustrate the capabilities of the model, we present a number of results which show that the ABAKO compares well with customized models and simulations of ion population distribution. The utility of ABAKO for plasma spectroscopic applications is also outlined.

Presynaptic action of neurotensin on dopamine release through inhibition of D(2) receptor function

Background

Neurotensin (NT) is known to act on dopamine (DA) neurons at the somatodendritic level to regulate cell firing and secondarily enhance DA release. In addition, anatomical and indirect physiological data suggest the presence of NT receptors at the terminal level. However, a clear demonstration of the mechanism of action of NT on dopaminergic axon terminals is lacking. We hypothesize that NT acts to increase DA release by inhibiting the function of terminal D2 autoreceptors. To test this hypothesis, we used fast-scan cyclic voltammetry (FCV) to monitor in real time the axonal release of DA in the nucleus accumbens (NAcc).

Results

DA release was evoked by single electrical pulses and pulse trains (10 Hz, 30 pulses). Under these two stimulation conditions, we evaluated the characteristics of DA D₂ autoreceptors and the presynaptic action of NT in the NAcc shell and shell/core border region. The selective agonist of D₂ autoreceptors, quinpirole (1 μM), inhibited DA overflow evoked by both single and train pulses. In sharp contrast, the selective D₂ receptor antagonist, sulpiride (5 μM), strongly enhanced DA release triggered by pulse trains, without any effect on DA release elicited by single pulses, thus confirming previous observations. We then determined the effect of NT (8–13) (100 nM) and found that although it failed to increase DA release evoked by single pulses, it strongly enhanced DA release evoked by pulse trains that lead to prolonged DA release and engage D₂ autoreceptors. In addition, initial blockade of D₂ autoreceptors by sulpiride considerably inhibited further facilitation of DA release generated by NT (8–13).

Conclusion

Taken together, these data suggest that NT enhances DA release principally by inhibiting the function of terminal D₂ autoreceptors and not by more direct mechanisms such as facilitation of terminal calcium influx.

A nomogram predictive of non-sentinel lymph node involvement in breast cancer patients with a sentinel lymph node micrometastasis

PURPOSE

Predictive factors of non-sentinel lymph node (NSN) involvement at axillary lymph node dissection (ALND) have been studied in the case of sentinel node (SN) involvement, with validation of a nomogram. This nomogram is not accurate for SN micrometastasis. The purpose of our study was to determine a nomogram for predicting the likelihood of NSN involvement in breast cancer patients with a SN micrometastasis.

METHODS

We collated 909 observations of SN micrometastases with additional ALND. Characteristics of the patients, tumours and SN were analysed.

RESULTS

Involvement of SN was diagnosed 490 times (53.9%) with standard staining (HES) and 419 times solely on immunohistochemical analysis (IHC) (46.1%). NSN invasion was observed in 114 patients (12.5%), whereas 62.3% (71) had only one NSN involved and 37.7% (43) two or more NSN involved. In multivariate analysis, significant predictive factors were: tumour size (pT stage < or = 10 mm or >11 and < or = 20 or >20 mm [odds ratio (OR) 2.1 and 3.43], micrometastases detected by HES or IHC [OR 1.64], presence or absence of lymphovascular invasion (LVI) [OR 1.76], tumour histological type mixed or not [OR 2.64]. The rate and probability of NSN involvement with the model are given for 24 groups, with a representation by a nomogram.

CONCLUSION

One group, corresponding to 10.1% of the patients, was associated with a risk of NSN involvement of less than 5%, and five groups, corresponding to 29.8% of the patients, were associated with a risk < or = 10%. Omission of ALND could be proposed with minimal risk for a low probability of NSN involvement.

Case volume and mortality in haematological patients with acute respiratory failure

High case volume is associated with improved survival in medical and surgical conditions. The present study sought to determine whether intensive care unit (ICU) case volume was associated with survival of critically ill patients with haematological malignancies and acute respiratory failure (ARF). A regional database containing data from 1,753 haematological patients with ARF admitted to 28 medical ICUs from 1997 to 2004 was used. Multivariate analysis using mixed models was performed to adjust for severity of illness and other confounding factors, including a propensity score that incorporates differences between ICUs with different case volumes. The three case volume tertiles were: low volume (<12 admissions per year), intermediate volume (12-30 admissions per year), and high volume (>30 admissions per year). In univariate analyses, ICU case volume was not associated with ICU mortality. After adjusting for prognostic factors for ICU mortality and the propensity score, patients in high-volume ICUs had lower mortality than other patients. A case volume increase of one admission per year led to a significant mortality reduction with an odds ratio of 0.98 (95% confidence limits 0.97-0.99). Mortality was independently associated with severity of organ dysfunction. In intensive care units admitting larger numbers of critically ill haematological patients with acute respiratory failure, mortality was lower than in other intensive care units. The mechanisms of the relationship between volume and outcome among haematological patients with acute respiratory deserve additional studies.

Dressings for acute and chronic wounds: a systematic review

OBJECTIVE

To critically review the literature on the efficacy of modern dressings in healing chronic and acute wounds by secondary intention.

DATA SOURCES

Search of 3 databases (MEDLINE, EMBASE, and the Cochrane Controlled Clinical Trials Register) from January 1990 to June 2006, completed by manual research, for articles in English and in French.

STUDY SELECTION

The end points for selecting studies were the rate of complete healing, time to complete healing, rate of change in wound area, and general performance criteria (eg, pain, ease of use, avoidance of wound trauma on dressing removal, ability to absorb and contain exudates). Studies were selected by a single reviewer. Overall, 99 studies met the selection criteria (89 randomized controlled trials [RCTs], 3 meta-analyses [1 of which came from 1 of the selected systematic reviews], 7 systematic reviews, and 1 cost-effectiveness study).

DATA EXTRACTION

The RCTs, meta-analyses, and cost-effectiveness studies were critically appraised by 2 reviewers to assess the clinical evidence level according to a modification of Sackett's 1989 criteria. Ninety-three articles were finally graded.

DATA SYNTHESIS

We found no level A studies, 14 level B studies (11 RCTs and 3 meta-analyses), and 79 level C studies. Hydrocolloid dressings proved superior to saline gauze or paraffin gauze dressings for the complete healing of chronic wounds, and alginates were better than other modern dressings for debriding necrotic wounds. Hydrofiber and foam dressings, when compared with other traditional dressings or a silver-coated dressing, respectively, reduced time to healing of acute wounds.

CONCLUSIONS

Our systematic review provided only weak levels of evidence on the clinical efficacy of modern dressings compared with saline or paraffin gauze in terms of healing, with the exception of hydrocolloids. There was no evidence that any of the modern dressings was better than another, or better than saline or paraffin gauze, in terms of general performance criteria. More wound care research providing level A evidence is needed.

Consensus panel recommendations for chronic and acute wound dressings

OBJECTIVE

To seek a consensus on recommendations that would help health professionals choose appropriate wound dressings in daily practice, since a systematic review found only limited evidence to support reported indications for modern wound dressings.

PARTICIPANTS

A steering committee selected a panel of 27 experts with no declared conflicts of interest from lists of nursing staff and physicians (specialists or general practitioners) with long-standing experience of wound care. The lists were put forward by 15 French learned societies.

EVIDENCE

The panelists received a recent systematic review of the literature, a classification of indications established by a working group, and definitions for the dressings.

CONSENSUS PROCESS

The steering committee designed questionnaires on chronic wounds and on acute wounds including burns for each of the 2 panels. The consensus method was derived from the nominal group technique adapted by RAND/UCLA. Panelists rated the relevance of each possible dressing-indication combination on the basis of the published evidence and their own experience. After the first round of rating, they met to discuss results and propose recommendations before taking part in a second round of rating. The working group peer reviewed the final recommendations.

CONCLUSIONS

A strong consensus was reached for use of the following combinations: for chronic wounds, (1) debridement stage, hydrogels; (2) granulation stage, foam and low-adherence dressings; and (3) epithelialization stage, hydrocolloid and low-adherence dressings; and for the epithelialization stage of acute wounds, low-adherence dressings. For specific situations, the following dressings were favored: for fragile skin, low-adherence dressings; for hemorrhagic wounds, alginates; and for malodorous wounds, activated charcoal.

Guidelines for doctors attending detainees in police custody: a consensus conference in France

Medical practice in police custody needs to be harmonized. A consensus conference was held on 2-3 December 2004 in Paris, France. The health, integrity, and dignity of detainees must be safeguarded. The examination should take place in the police station so that the doctor can assess the conditions in which the detainee is being held. If the minimum conditions needed for a medical examination are not available, the doctor may refuse to express an opinion as to whether the detainee is fit to be held in custody or may ask for the detainee to be examined in a hospital. Doctors are subject to a duty of care and prevention. They should prescribe any ongoing treatment that needs to be continued, as well as any emergency treatment required. Custody officers may monitor the detainee and administer medication. However, their role should not be expected to exceed that required of the detainee's family under normal circumstances and must be specified in writing on the medical certificate. Doctor's opinion should be given in a national standard document. If the doctors consider that the custody conditions are disgraceful, they may refuse to express an opinion as to whether the detainee is fit for custody.

[Laparoscopy-assisted vaginal pelvic exenteration]

OBJECTIVE

The aim of the study was to evaluate the feasibility, morbidity and survival outcome of laparoscopy-assisted vaginal pelvic exenteration.

PATIENTS AND METHODS

Since 2000, 7 en-bloc pelvic exenteration combining a vaginal or perineal approach and laparoscopic approach have been performed in our cancer center associated with complex laparoscopic reconstruction. All patients but one received previous irradiation. Two patients underwent a total pelvic exenteration; three patients an anterior and middle exenteration; two patients a middle and posterior exenteration. Urinary system was reconstructed with an ileal loop in one case, with a hand-assisted laparoscopic Miami pouch in four cases. Reconstruction of the vagina was performed with an omental cylinder in three cases, with a gluteal thigh flap in one case. A colorectal anastomosis was performed in three patients, one patient had an end colostomy. A mini-laparotomy conversion was necessary in one case because of a pelvic side involvement to perform an intraoperative irradiation.

RESULTS

Mean time of the procedure was 6.5 hours with peroperative bleeding less than 500 cm3. Four patients presented minor complications. No revision of the Miami pouch was necessary. Mean length of hospital stay was 27 days. The four patients with a Miami pouch were able to self catheterize at the time of discharge. Mean follow-up was 14 months. Four patients died of the disease (three were metastatic). One patient presented a local recurrence. Two patients are free of disease.

DISCUSSION AND CONCLUSION

Laparoscopic or laparoscopy-assisted vaginal pelvic exenteration followed by reconstruction is feasible with curative intent in selected patients.

[Transient ischemic stroke]

According to the new definition proposed by the TIA working group, transient ischemic stroke (TIA) is "a brief episode of neurologic dysfunction caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than one hour, and without evidence of acute infarction." Patient presenting with a TIA should be investigated and treated urgently because the risk of ischemic stroke is about 10% at one month with 50% of these events occurring during the first 48 hours. Atherosclerosis, cardioembolism and small vessel disease account for the majority of TA. Aspirin should be started as soon as possible after brain imaging has been performed. Other treatment such as oral anticoagulants or carotide surgery may be necessary, depending on the result of the electronical work up.

Membranous nephropathy and cancer: Epidemiologic evidence and determinants of high-risk cancer association

The association between membranous nephropathy (MN) and cancer is often mentioned in textbooks but poorly substantiated, and the characteristics of cancer-associated MN are unknown. To address these questions, we studied a cohort of 240 patients with MN, among them 24 had malignancy at the time of renal biopsy or within a year thereafter. The incidence of cancer was significantly higher in these patients than in the general population (standardized incidence ratio 9.8 [5.5-16.2] for men and 12.3 [4.5-26.9] for women). The frequency of malignancy increased with age. At the time of diagnosis, clinical presentation did not differ between the patients with cancer-associated MN and those with idiopathic MN, but smoking was more frequent among patients with cancer. Analysis of renal biopsies revealed that the number of inflammatory cells infiltrating the glomeruli was significantly higher in patients with cancer-associated MN (P = 0.001). The best cutoff value for distinguishing malignancy-related cases from controls was eight cells per glomerulus. Using this threshold led to a diagnosis of cancer-associated MN with a specificity of 75% and a sensitivity of 92%. In patients with cancer-associated MN, there was a strong relationship between reduction of proteinuria and clinical remission of cancer (P < 0.001). In conclusion, our study provides epidemiologic evidence of an excess of cancer risk in patients with MN. It also shows that age, smoking, and the presence of glomerular leukocytic infiltrates strongly increase the likelihood of malignancy in MN patients.

[Laparoscopic surgery in gynaecological tumors]

The use of laparoscopic staging and/or surgery in the field of gynaecological oncology was pioneered in the late 80's and the first reports were published in the early 90's. The issue has been initially most controversial, and is still debated, with some justification considering the possible adverse consequences of surgical mismanagement of gynaecologic malignancy. Since then, a number of papers have confirmed the absence of significant adverse effects on survival after laparoscopic diagnosis or surgery in gynaecological cancers. New developments cover virtually all the basic techniques in cancer surgery, including major exenterative surgery. The use of extraperitoneal technique for aortic dissections is emerging as a new tool. New indications, such as radical vaginal trachelectomy (Dargent operation), radical parametrectomy, pelvic sentinel node identification, decisional laparoscopy in adnexal malignancies, or the use of pretherapeutic surgical staging of uterine cancers, have been developed in direct relation with the use of laparoscopic techniques. Worldwide interest clearly demonstrates that laparoscopic techniques must now be part of the armamentarium of the gynaecologic oncologist. Postoperative morbidity and recurrence risk do not seem to be affected. Cost-efficiency of laparoscopic procedures is based on the reduction of hospital stay and recovery time, particularly in obese patients. Combined training in gynaecologic oncology and in laparoscopic and/or vaginal surgery is more than ever mandatory to reduce the operating time, which is becoming similar to laparotomy in experiences hands, and avoid the risk of inadequate staging or management of pelvic malignancies.

Clinical practice guidelines: medical follow-up of patients with asthma--adults and adolescents

The follow-up of patients with asthma should focus on asthma control (disease course over a number of weeks).