Setting up regional diagnostic reference levels for pediatric interventional cardiology in Latin America and the Caribbean countries: preliminary results and identified challenges.

The goal of the present study was to propose a set of preliminary regional diagnostic reference levels (DRLs) for pediatric interventional cardiology (IC) procedures in Latin America and the Caribbean countries, classified by age and weight groups. The study was conducted in the framework of the Optimization of Protection in Pediatric Interventional Radiology in Latin America and the Caribbean program coordinated by the World Health Organization and the Pan American Health Organization in cooperation with the International Atomic Energy Agency. The first step of the program was focused on pediatric IC. Dose data from diagnostic and therapeutic procedures were collected between December 2020 and December 2021. Regional DRLs were set as the third quartile of patient dose data (kerma area product) collected in 18 hospitals from 10 countries in an initial sample of 968 procedures. DRLs were set for four age bands and five weight ranges. The values obtained for the four age bands (<1 yr, 1 to <5 yr, 5 to <10 yr and 10 to <16 yr) were 2.9, 6.1, 8.8 and 14.4 Gy cm2for diagnostic procedures, and 4.0, 5.0, 10.0 and 38.1 Gy cm2for therapeutic procedures, respectively. The values obtained for the five weight bands (<5 kg, 5 to <15 kg, 15 to <30 kg, 30 to <50 kg and 50 to <80 kg) were 3.0, 4.5, 8.1, 9.2 and 26.8 Gy cm2for diagnostic procedures and 3.7, 4,3, 7.3, 16.1 and 53.4 Gy cm2for therapeutic procedures, respectively. While initial data were collected manually as patient dose management systems (DMSs) were not available in most of the hospitals involved in the program, a centralized automatic DMS for the collection and management of patient dose indicators has now been introduced and is envisaged to increase the sample size. The possibility of alerting on high dose values and introducing corrective actions will help in optimization.

Modulated scattering technique in the terahertz domain enabled by current actuated vanadium dioxide switches.

The modulated scattering technique is based on the use of reconfigurable electromagnetic scatterers, structures able to scatter and modulate an impinging electromagnetic field in function of a control signal. The modulated scattering technique is used in a wide range of frequencies up to millimeter waves for various applications, such as field mapping of circuits or antennas, radio-frequency identification devices and imaging applications. However, its implementation in the terahertz domain remains challenging. Here, we describe the design and experimental demonstration of the modulated scattering technique at terahertz frequencies. We characterize a modulated scatterer consisting in a bowtie antenna loaded with a vanadium dioxide switch, actuated using a continuous current. The modulated scatterer behavior is demonstrated using a time domain terahertz spectroscopy setup and shows significant signal strength well above 0.5 THz, which makes this device a promising candidate for the development of fast and energy-efficient THz communication devices and imaging systems. Moreover, our experiments allowed us to verify the operation of a single micro-meter sized VO2 switch at terahertz frequencies, thanks to the coupling provided by the antenna.

Self-biased reconfigurable graphene stacks for terahertz plasmonics.

The gate-controllable complex conductivity of graphene offers unprecedented opportunities for reconfigurable plasmonics at terahertz and mid-infrared frequencies. However, the requirement of a gating electrode close to graphene and the single 'control knob' that this approach offers limits the practical implementation and performance of these devices. Here we report on graphene stacks composed of two or more graphene monolayers separated by electrically thin dielectrics and present a simple and rigorous theoretical framework for their characterization. In a first implementation, two graphene layers gate each other, thereby behaving as a controllable single equivalent layer but without any additional gating structure. Second, we show that adding an additional gate allows independent control of the complex conductivity of each layer within the stack and provides enhanced control on the stack equivalent complex conductivity. These results are very promising for the development of THz and mid-infrared plasmonic devices with enhanced performance and reconfiguration capabilities.

ZRF1 controls the retinoic acid pathway and regulates leukemogenic potential in acute myeloid leukemia.

Acute myeloid leukemia (AML) is frequently linked to epigenetic abnormalities and deregulation of gene transcription, which lead to aberrant cell proliferation and accumulation of undifferentiated precursors. ZRF1, a recently characterized epigenetic factor involved in transcriptional regulation, is highly overexpressed in human AML, but it is not known whether it plays a role in leukemia progression. Here, we demonstrate that ZRF1 depletion decreases cell proliferation, induces apoptosis and enhances cell differentiation in human AML cells. Treatment with retinoic acid (RA), a differentiating agent currently used to treat certain AMLs, leads to a functional switch of ZRF1 from a negative regulator to an activator of differentiation. At the molecular level, ZRF1 controls the RA-regulated gene network through its interaction with the RA receptor α (RARα) and its binding to RA target genes. Our genome-wide expression study reveals that ZRF1 regulates the transcription of nearly half of RA target genes. Consistent with our in vitro observations that ZRF1 regulates proliferation, apoptosis, and differentiation, ZRF1 depletion strongly inhibits leukemia progression in a xenograft mouse model. Finally, ZRF1 knockdown cooperates with RA treatment in leukemia suppression in vivo. Taken together, our data reveal that ZRF1 is a key transcriptional regulator in leukemia progression and suggest that ZRF1 inhibition could be a novel strategy to be explored for AML treatment.

Acclimatization of rats after ground transportation to a new animal facility.

This study aimed to assess the time needed by rats, which had not been previously transported, to acclimate to a new environment after 5 h of van transport, using physiological parameters as measures of acclimatization. Animal shipping boxes and transport van conditions were standardized to minimize stress factors that could be associated with transport. Heart rate (HR), body temperature and activity levels were measured in the rats before and after transport using previously implanted radio-telemetry transmitters. Body weight was also recorded. All parameters were changed significantly except for body temperature. Results suggest that rats take three days to acclimate to a new environment, as measured by the physiological parameters of body weight, HR and activity.

Antioxidant patterns (superoxide dismutase, glutathione reductase, and glutathione peroxidase) in kidneys from non-heart-beating-donors: experimental study.

INTRODUCTION: The evolution of renal antioxidant concentrations in the different phases of a non-heart-beating donor (NHBD) transplant after prolonged warm ischemia (40 and 90 minutes) and the effect of normothermic extracorporeal recirculation (37 degrees C) for 30 minutes were evaluated on antioxidant tissue concentrations in the kidney. METHODS: Forty pairs of pigs, were divided into groups of 10 as follows: group 0, control donor with beating heart; group 1, 40 minutes of warm ischemia without recirculation by cardiopulmonary bypass pump (groups 2 and 3); group 2, 40 minutes of warm ischemia and recirculation for 30 minutes at 37 degrees C; and group 3, 90 minutes of warm ischemia and recirculation for 30 minutes at 37 degrees C. The concentrations of superoxide dismutase (SOD), glutathione peroxidase, and glutathione reductase were determined at the tissue level by biopsy at baseline the end of warm ischemia, the end of recirculation, at the end of cold ischemia, and 1 hour after reperfusion. RESULTS: SOD was consumed at the end of the cold ischemia phase (P < .009) and increased during reperfusion (P < .02). Glutathione reductase was consumed during the cold ischemia phase (P < .04). In kidneys submitted to 40 minutes of warm ischemia, SOD was consumed during the cold ischemia phase (P < .04) and increased with reperfusion (P < .03). In kidneys undergoing 90 minutes of hot ischemia, SOD was consumed during cold ischemia (P < .04) and glutathione reductase during extracorporeal recirculation (P < .01). CONCLUSIONS: Recirculation increased the tissue level of SOD at the end of the cold ischemia period.

Ultrasound-guided skeletal biopsies.

OBJECTIVE: Percutaneous biopsy of skeletal lesions is a widely used diagnostic technique that involves fluoroscopic or computerized tomography guidance. The objective of this report is to describe the use of ultrasonography in the guidance of percutaneous biopsy of skeletal lesions. DESIGN AND PATIENTS: We employed ultrasound to guide percutaneous biopsy in 65 skeletal lesions in 63 patients (30 male and 33 female) whose ages ranged from 1 to 82 years (mean 47.2 years ). The lesions were divided into four groups: group 1 ( n=41) were lytic with a soft tissue mass, group 2 ( n=14) were lytic with a disrupted cortex without a soft tissue mass, group 3 ( n=4) were lytic with an intact cortex and group 4 ( n=6) were sclerotic lesions. Different techniques and materials were used in each group. RESULTS: Cytologic assessment obtained the diagnosis in 50 cases, (success rate 76.9%), histology in 56 cases (86.1%) and a combination of both in 60 cases (92.3%). There were no complications. CONCLUSIONS: Ultrasound is a highly accurate and safe method of guidance in percutaneous biopsy of bone lesions, either lytic or sclerotic, because it can identify subtle changes in the cortical and the associated soft tissue component.

[Echography-guided percutaneous biopsy of pleural lesions and effusions]. / Biopsia percutánea de lesiones y derrames pleurales dirigida por ecografía.

Our experience in the use of ultrasonic echography (UE) is exposed as a guide for directing small lesions and pleural effusions percutaneous lesions with an unknown grounds. We have done pleural percutaneous biopsy using UE as guide in 45 patients. The needle diameter ranges between 17 and 19.5 G. Lesions were benign for 16 patients and malignant for 29. The right result was obtained in 93% of the cases. There were not complications. We conclude that echography-directed pleural biopsy presents an excellent diagnostic profitability, it improves the results obtained with blind biopsy with Cope's needle and it must precede thoracoscopy by means of its less aggressiveness.

Characterization of solid liver lesions with color and pulsed Doppler imaging.

BACKGROUND: To assess the usefulness of color Doppler and duplex sonography in the characterization of solid liver lesions. METHODS: We performed color Doppler and duplex sonography on 106 solid hepatic lesions. With color Doppler, we evaluated the aspect and distribution of tumoral vessels. The pulsed Doppler parameters considered were only those showing the highest systolic peak velocity values. RESULTS: Intratumoral color and pulsed Doppler signals were obtained in 81% (59/73) of malignant tumors (p < 0. 0001) but only in 18% (6/33) of benign tumors. Ninety-six percent (45/47) of the lesions with arterial intratumoral and peritumoral signals were malignant, whereas 4% were benign (p < 0.0001). Only eight (11%) malignant lesions had intratumoral venous signal vis-a-vis 23 (70%) benign. Twelve cases showing intratumoral venous Doppler signal as a single finding were benign. No statistically significant differences were observed in the quantitative parameters recorded by pulsed Doppler (Student t test, p < 0.05), there having been a clear overlapping in the values obtained in benign and malignant lesions. CONCLUSIONS: (a) The type of signal (arterial or venous) and its distribution detected by color and pulsed Doppler is more helpful than the assessment of the spectral quantitative parameters obtained by pulsed Doppler. (b) The presence of intratumoral venous flow remarkably suggests benignancy. (c) The presence of both intra- and peritumoral arterial flow in the same lesion strongly suggests malignancy.

Eosinophilic gastroenteritis: percutaneous biopsy under ultrasound guidance.

Eosinophilic gastroenteritis (EG) is an unusual disorder that is characterized by diffuse or scattered eosinophilic infiltration of the digestive tract. The diagnosis is based on histology obtained by capsule, endoscopic, laparoscopic, or laparotomy biopsy. The eosinophilic infiltration produces thickening of the small bowel wall that can be observed by using sonography. The appearance produces the pseudokidney sign that can be used to guide biopsy. We report the first case of EG diagnosed by percutaneous biopsy under ultrasound guidance.