Radiation shielding assessment for interventional radiology personnel: Geant4 dosimetry of lead-free compositions.

The inherent biological hazards associated with ionizing radiation necessitate the implementation of effective shielding measures, particularly in medical applications. Interventional radiology, in particular, poses a unique challenge as it often exposes medical personnel to prolonged periods of high x-ray doses. Historically, lead and lead-based compounds have been the primary materials employed for shielding against photons. However, the drawbacks of lead, including its substantial weight causing personnel's inflexibility and its toxicity, have raised concerns regarding its long-term impact on both human health and the environment. Barium tantalate has emerged as a promising alternative, due to its unique attenuation properties against low-energy x-rays, specifically targeting the weak absorption area of lead. In the present study, we employ the Geant4 Monte Carlo simulation tool to investigate various formulations of barium tantalate doped with rare earth elements. The aim is to identify the optimal composition for shielding x-rays in the context of interventional radiology. To achieve this, we employ a reference x-ray spectrum typical of interventional radiology procedures, with energies extending up to 90 keV, within a carefully designed simulation setup. Our primary performance indicator is the reduction in air kerma transmission. Furthermore, we assess the absorbed doses to critical organs at risk within a standard human body phantom protected by the shield. Our results demonstrate that specific concentrations of the examined rare earth impurities can enhance the shielding performance of barium tantalate. To mitigate x-ray exposure in interventional radiology, our analysis reveals that the most effective shielding performance is achieved when using barium tantalate compositions containing 15% Erbium or 10% Samarium by weight. These findings suggest the possibility of developing lead-free shielding solutions or apron for interventional radiology personnel, offering a remarkable reduction in weight (exceeding 30%) while maintaining shielding performance at levels comparable to traditional lead-based materials.

Chromosomal aberrations in ascetic fluid of metastatic gastric cancer patients: A clustering analysis.

To date, no specific pattern of chromosomal abnormalities has been established in gastric cancer (GC). Cytogenetic analysis was performed using G-banding and fluorescence in situ hybridization (FISH) in 9 ascetic fluids from GC patients, and the clustering patterns of chromosomal abnormalities were studied. Twenty-six different types of chromosomal abnormalities were identified. In contrast to structural abnormalities, the gain or loss of chromosomes was infrequent. Moreover, five main clusters of chromosomal abnormalities were identified by clustering analysis. Extensive cytogenetic complexity, specific chromosomal abnormalities and karyotype heterogeneity are the main characterizations of GC. Some of the recurrent and novel chromosomal abnormalities with distinct clustering patterns identified in this study may play important roles for GC initiation and progression and could serve as promising diagnostic and prognostic markers in GC patients.

An Investigation to Determine an Optimum Protective Garment Material in Nuclear Medicine.

AIM: The aim of this study is to find an optimum material to protect garment for protection against 99Tcm radionuclide. MATERIALS AND METHODS: Monte Carlo simulation code was applied to investigate radiation attenuation of 13 shielding materials including: Ba, gray Sn, white Sn, Sb, Bi, Bi2O3, BaSO4, Sn/W, Sb/W, Pb and W with thicknesses of 0.5 and 1 mm to determine an optimum protective garment material in nuclear medicine against 99Tcm. Furthermore, the dose enhancement on the staff body was investigated for shielding materials such as tungsten and lead. RESULTS: The findings of the simulations show that the maximum and minimum attenuation obtained with thicknesses of 1 mm W and 1 mm BaSO4 were 96.46% and 14.2%, respectively. The results also demonstrate that tungsten does not cause any dose enhancement on staff body but this is not true for lead. Tungsten provides the highest radiation attenuation without dose enhancement on the body of staff. CONCLUSION: Among materials evaluated, tungsten is the optimum material and it can be applied for the design of protective garment for nuclear medicine staff against 99Tcm.

Effectiveness of regionalization of trauma care services: a systematic review.

OBJECTIVES: Improving trauma systems in various forms has always been an important aspect of health policy. While several papers have reported the implementation of a structured trauma system of care, research evidence on the effectiveness of such regionalization for improvement in trauma outcome is limited. STUDY DESIGN: Systematic review. METHOD: Medline, EMbase, EconLit and Health Management Information Consortium were searched, using sensitive search terms, for interventional studies that reported a trauma regionalization system as their intervention, and compared important outcomes such as mortality and preventable deaths. At least two authors assessed eligibility for inclusion and risk of bias, and extracted data from the included studies. As meta-analysis was not possible for all studies, two controlled before-after studies were included in the meta-analysis, and a narrative analysis was conducted for the other studies. RESULTS: After title and abstract sifting, 66 papers were retrieved. After reading the full texts, a total of 24 studies from the USA, UK, Canada, Australia, and the Netherlands were included in this review. In spite of variation in study specifications, most were before-after studies with a high risk of bias. Although a reduction in mortality was shown in most studies, only two studies were eligible for meta-analysis, and the results showed a significant reduction in mortality after implementation of an organized trauma system (odds ratio 0.840, 95% confidence interval 0.756-0.924; P = 0.00). CONCLUSION: Correlation was found between a regionalized network of trauma care and a reduction in trauma-related mortality, based on studies that did not exclude the effects of other concurrent changes on observed reductions. It is recommended that more studies with robust research designs should be conducted in a more diverse range of countries to assess the effectiveness of regionalization. Despite this limitation, the present findings support the regionalization of trauma care services.

Assessing medical students' communication skills by the use of standardized patients: emphasizing standardized patients' quality assurance.

OBJECTIVE: The objective structured examination is one of the most valid, reliable, and effective tools for assessing clinical and communication skills, often by use of standard patients (SPs). SPs can also be assessors of those skills. One of the crucial areas when utilizing SP-based assessment is the quality and consistency assurance of their portrayal of the case and their ability to fill in checklists in an adequate way. The aim of this study was to assess the validity and reliability of SPs' ability to assess students' communication skill via a Calgary-Cambridge checklist. METHOD: This cross-sectional and correlational study was conducted at the Tehran University of Medical Science. We first analyzed validity; the criterion validity of the SPs' filling in the checklists was assessed through determining the correlation between the SPs' completed checklists and the checklists filled in by three physician raters individually and then reproducibility: it was assessed by a test-retest approach inter-rater reliability. RESULT: The mean correlation for assessing the validity of SPs' completed checklists by individual SPs was 0.81. The inter-rater reliability was calculated by kappa coefficient, and the total correlation among the three raters was 0.85. The reliability of the test-retest approach showed no significant differences between the test and re-test results. CONCLUSION: The increased number of medical students and different faculties' responsibilities such as doing educational, research, and health services duties assessing medical student communication skills is a complex issue. The results of our study showed that trained SPs can be used as a valid tool to assess medical students' communication skills, which is also more cost effective and reduces work load of medical faculties.

Reduction of mycotoxins in white pepper.

A simple method for the reduction of aflatoxins B1 (AFB1), B2 (AFB2), G1 (AFG1), G2 (AFG2) and ochratoxin A (OTA) in white pepper was studied. Response surface methodology (RSM) was applied to determine the effect of four variables, which included time (20-60 min), temperature (30-70°C), calcium hydroxide (Ca(OH)2) (0-1%) and hydrogen peroxide (H2O2) (1-3%) during the washing step of white pepper. The efficacy of the method was evaluated by the determination of mycotoxins by HPLC with fluorescence detection (FD). Statistical analysis showed that the experimental data could be adequately fitted into a second-order polynomial model, with a multiple regression coefficient (R²) in the range of 0.805-0.907 for AFG2 and AFG1, respectively. The optimal condition was 57.8 min, 62.0°C, of 0.6% (w/v) and 2.8% (v/v) for time, temperature, Ca(OH)2 and H2O2 respectively. By applying the optimum condition, the mycotoxins reduction was found to be in the range of 68.5-100% for AFB2 and AFG1 respectively.

Reduced-intensity conditioning hematopoietic SCT for pediatric patients with LAD-1: clinical efficacy and importance of chimerism.

Pediatric patients with leukocyte adhesion deficiency type-I (LAD-I) experience severe and recurrent life-threatening bacterial infections with failure of pus formation and delayed wound healing. LAD-I is a rare inherited disease caused by mutation in the leukocyte CD18 integrin expression, resulting in defective adherence and migration of leukocytes, in particular neutrophilic granulocytes through the intravascular space. Hematopoietic SCT is the only curative treatment option available to patients with LAD-I. Since 2007, in a prospective trial, reduced-intensity conditioning regimen have been developed for 10 consecutive patients with LAD-I who were referred to our center. Based upon available data, it is the first time that such a number of patients affected by LAD-I have been treated with this regimen. This study attempts to show that reduced-intensity regimen leads to a favorable result in LAD-I patients even in those who have experienced comorbid complications. Following transplantation, some patients develop mixed chimerism, however, in our study mixed chimerism was not followed by transplant rejection.

The effect of chemical treatment on reduction of aflatoxins and ochratoxin A in black and white pepper during washing.

The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B(1), B(2), G(1) and G(2) and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B(1), which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05).

Natural occurrence of ochratoxin A contamination in commercial black and white pepper products.

The concentration of ochratoxin A (OTA) in 120 commercial pepper (84 pre-packed and 36 bulk samples), which consist of local and imported white and black pepper in powder and seed form in Malaysia were determined. The objective of the study was to investigate and compare OTA concentration in black pepper and white pepper being commercialized in Malaysia. Determination method was based on HPLC with fluorescence detection coupled with immunoaffinity column clean-up step. Mobile phase consisted of acetonitrile-water-acetic acid (49.5:49.5:1.0, v/v/v), and flow rate was 1 ml/min. The LOD was 0.02 ng/g, and the average recovery values of OTA ranged from 79.5 to 92.0% in black pepper and 81.2-90.3% in white pepper. A total of 57 samples (47.5%) were contaminated with OTA ranging from 0.15 to 13.58 ng/g. The results showed that there was a significant difference between type of pepper and brands. OTA concentration in black pepper was significantly higher than white pepper (p < 0.05). The highest concentration of ochratoxin, 13.58 ng/g, was detected in a sample of black pepper seed followed by 12.64 ng/g in a sample of black pepper powder, both were bulk samples purchased from open market.

Survey of aflatoxins in retail samples of whole and ground black and white peppercorns.

A total of 126 local and imported samples of commercial white and black pepper in Malaysia were analysed for aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1, AFG2) content using high-performance liquid chromatography (HPLC) with a fluorescence detector (FD). An acetonitrile-methanol-water (17 : 29 : 54; v/v) mixture was used as a mobile phase and clean-up was using an immunoaffinity column (IAC). Seventy out of 126 (55.5%) samples were contaminated with total aflatoxins, although only low levels of aflatoxins were found ranging from 0.1 to 4.9 ng g(-1). Aflatoxin B1 showed the highest incidence of contamination and was found in all contaminated samples. There was a significant difference between type of samples and different brands (p < 0.05). The results showed black peppers were more contaminated than white peppers.

Alpha rhythm and hypofrontality in schizophrenia.

OBJECTIVE: To reveal the EEG correlates of resting hypofrontality in schizophrenia (SZ). METHOD: We analyzed the whole-head EEG topography in 14 patients compared to 14 matched controls by applying a new parameterization of the multichannel EEG. We used a combination of power measures tuned for regional surface mapping with power measures that allow evaluation of global effects. RESULTS: The SZ-related EEG abnormalities include i) a global decrease in absolute EEG power robustly manifested in the alpha and beta frequency bands, and ii) a relative increase in the alpha power over the prefrontal brain regions against its reduction over the posterior regions. In the alpha band both effects are linked to the SZ symptoms measured with Positive and Negative Symptom Scales and to chronicity. CONCLUSION: As alpha activity is related to regional deactivation, our findings support the concept of hypofrontality in SZ and expose the alpha rhythm as a sensitive indicator of it.

Carotid blood-flow velocity changes detected by Doppler ultrasound in determination of brain death in children. A preliminary report.

To investigate the value of Doppler ultrasonography of the carotid arteries as a diagnostic test for the determination of brain death in children, we enrolled 17 patients in a blinded fashion in the pediatric intensive care unit of Memorial Miller Children's Hospital of Long Beach between the period of December 1990 and October 1992. After institutional review board approval and parental consent, children who sustained severe brain injury underwent Doppler ultrasonography study of their carotid arteries. Seven of 17 patients were diagnosed as having brain death by clinical criteria (complete loss of cerebral and brainstem functions) and electroencephalogram (EEG). Five of seven (71%) patients with the diagnosis of brain death had bilateral reverse flow (characteristic of increased cerebrovascular resistance and absent cerebral circulation) on their Doppler ultrasonography, yielding a specificity of 100% and sensitivity of 71.4% (P = 0.01). All surviving patients (five) and the five who did not fulfill the brain-death criteria at the time of Doppler ultrasonography and were later taken off life supportive measures had normal Doppler findings. These data indicate that Doppler ultrasonography of the carotid arteries is a very specific test and can be used as an adjunctive modality for determination of brain death in children.

[Synthesis and biological effects of new N,N-disubstituted 5-alkyliden- and 5-aralkyliden-3-aminorhodanines]. / Synthese und biologische Wirksamkeit neuer N,N-disubstituierter 5-Alkyliden- bzw. 5-Aralkyliden-3-aminorhodanine.

Numerous novel N,N-disubstituted 5-alkyliden- or 5-aralkyliden-3-aminorhodanines 2 have been prepared by condensation of carbonyl compounds with 1. The effectiveness of some derivatives in an "akanthose test" with hairless mice was shown.