Processes controlling programmed cell death of root velamen radicum in an epiphytic orchid.

BACKGROUND AND AIMS: Development of the velamen radicum on the outer surface of the root epidermis is an important characteristic for water uptake and retention in some plant families, particularly epiphytic orchids, for survival under water-limited environments. Velamen radicum cells derive from the primary root meristem; however, following this development, velamen radicum cells die by incompletely understood processes of programmed cell death (PCD). METHODS: We combined the use of transmission electron microscopy, X-ray micro-tomography and transcriptome methods to characterize the major anatomical and molecular changes that occur during the development and death of velamen radicum cells of Cymbidium tracyanum, a typical epiphytic orchid, to determine how PCD occurs. KEY RESULTS: Typical changes of PCD in anatomy and gene expression were observed in the development of velamen radicum cells. During the initiation of PCD, we found that both cell and vacuole size increased, and several genes involved in brassinosteroid and ethylene pathways were upregulated. In the stage of secondary cell wall formation, significant anatomical changes included DNA degradation, cytoplasm thinning, organelle decrease, vacuole rupture and cell wall thickening. Changes were found in the expression of genes related to the biosynthesis of cellulose and lignin, which are instrumental in the formation of secondary cell walls, and are regulated by cytoskeleton-related factors and phenylalanine ammonia-lyase. In the final stage of PCD, cell autolysis was terminated from the outside to the inside of the velamen radicum. The regulation of genes related to autophagy, vacuolar processing enzyme, cysteine proteases and metacaspase was involved in the final execution of cell death and autolysis. CONCLUSIONS: Our results showed that the development of the root velamen radicum in an epiphytic orchid was controlled by the process of PCD, which included initiation of PCD, followed by formation of the secondary cell wall, and execution of autolysis following cell death.

Multicenter, international study of CT practices and radiation doses from 10 African countries: An International Atomic Energy Agency (IAEA) baseline study.

PURPOSE: The objective of our IAEA-coordinated international study was to assess CT practices and radiation doses from multiple hospitals across several African countries. METHODS: The study included 13 hospitals from Africa which contributed information on minimum of 20 consecutive patients who underwent head, chest, and/or abdomen-pelvis CT. Prior to the data recording step, all hospitals had a mandatory one-hour training on the best practices in recording the relevant data elements. The recorded data elements included patient age, weight, protocol name, scanner information, acquisition parameters, and radiation dose descriptors including phase-specific CT dose index volume (CTDIvol in mGy) and dose length product (DLP in mGy.cm). We estimated the median and interquartile range of body-region specific CTDIvol and DLP and compared data across sites and countries using the Kruskal-Wallis H Test for non-normal distribution, analysis of variance. RESULTS: A total of 1061 patients (mean age 50 ± 19 years) were included in the study. 16 % of CT exams had no stated clinical indications for CT examinations of the head (32/343, 9 %), chest (50/281, 18 %), abdomen-pelvis (67/243, 28 %), and/or chest-abdomen-pelvis CT (24/194, 12 %). Most hospitals used multiphase CT protocols for abdomen-pelvis (9/11 hospitals) and chest CT (10/12 hospitals), regardless of clinical indications. Total median DLP values for head (953 mGy.cm), chest (405 mGy.cm), and abdomen-pelvis (1195 mGy.cm) CT were above the UK, German, and American College of Radiology Diagnostic Reference Levels (DRLs). CONCLUSIONS: Concerning variations in CT practices and protocols across several hospitals in Africa were demonstrated, emphasizing the need for better protocol optimization to improve patient safety.

Noise-optimized virtual monoenergetic imaging technology of the third-generation dual-source computed tomography and its clinical applications.

The third-generation dual-source computed tomography (DSCT) is among the most advanced imaging methods. It employs noise-optimized virtual monoenergetic imaging (VMI+) technology. It uses the frequency-split method to extract high-contrast image information from low-energy images and low-noise information from images reconstructed at an optimal energy level, combining them to obtain the final image with improved quality. This review is the first to summarize the results of clinical studies that primarily and recently evaluated the VMI+ technique based on tumor, blood vessel, and other lesion classification. We aim to assist radiologists in quickly selecting the appropriate energy level when performing image reconstruction for superior image quality in clinical work and providing several ideas for future scientific research of the VMI+ technique. Presently, VMI+ reconstruction is mostly used for images of various tumors or blood vessels, including coronary plaques, coronary stents, deep vein thromboses, pulmonary embolisms (PEs), active arterial hemorrhages, and endoleaks after endovascular aneurysm repair. In addition, VMI+ has been used for imaging children's heads, liver lesions, pancreatic lacerations, and reducing metal artifacts. Regarding the reconstruction at the optimal energy level, the VMI+ technique yielded a higher image quality than the pre-optimized virtual monoenergetic imaging (VMI) technique and single-energy CT. Moreover, either low concentrations of contrast medium or low iodine injection rates can be applied before VMI+ reconstruction at a low-energy level to reduce contrast agent-related kidney injury risk. After reconstructing an image at the optimal energy level, both the image's window width and level can also be adjusted to improve the image effect's reach and diagnosis suitability. To improve image quality and lesion-imaging clarity and reduce the use of contrast agents, VMI+ reconstruction technology has been applied clinically, in which the selection of energy level is the key to the whole reconstruction process. Our review summarizes these optimal levels for radiologists' reference and suggests new ideas for the direction of future VMI+ research.

FT-Raman Spectroscopy Study of the Remineralization of Microwave-Exposed Artificial Caries.

Dental caries is a microbially mediated disease that can result in significant tooth structure degradation. Although the preponderance of lesions is treated by surgical intervention, various strategies have been developed for its noninvasive management. Here, we use a novel approach for noninvasive treatment based on killing Streptococcus mutans with high-frequency microwave energy (ME). The rationale for this approach is based on modulating the pH of caries to a physiological state to enable spontaneous tooth remineralization from exogenous sources. In the present study, after demonstrating that ME kills >99% of S. mutans in planktonic cultures, 8 enamel slabs were harvested from a single tooth. Baseline mineral concentration at each of 12 points per slab was obtained using Fourier transform (FT)-Raman spectroscopy. Surface demineralization was subsequently promoted by subjecting all samples to an S. mutans acidic biofilm for 6 d. Half of the samples were then exposed to high-frequency ME, and the other half were used as controls. All samples were next subjected to a remineralization protocol consisting of two 45-min exposures per 24-h period in tryptic soy broth followed by immersion in a remineralizing solution for the remaining period. After 10 d, samples were removed and cleaned. FT-Raman spectra were again obtained at the same 12 points per sample, and the mineral concentration was determined. The effect of the remineralization protocol on the demineralized slabs was expressed as a percentage of mineral loss or gain relative to baseline. The mineral concentration of the microwave-exposed group collectively approached 100% of baseline values, while that of the control group was in the order of 40%. Differences between groups were significant (P = 0.001, Mann-Whitney U test). We concluded that killing of S. mutans by ME promotes effective remineralization of S. mutans-demineralized enamel compared with controls.

Additional Value of SPECT/CT to Tc-99m MAG3 Renal Scintigraphy in the Diagnosis of a Patient with Ureteroileal Fistula.

UNLABELLED: We performed Tc-99m MAG3 dynamic renal scintigraphy followed by a SPECT/CT imaging to a 38-yr-old woman who had a fistula in the lower urinary tract after a gynecological operation for diagnostic purposes. After scintigraphy, CT and fusion images were evaluated, it was observed that the activity in the right lower quadrant was actually in the ileal lumen. When early and late SPECT/CT images were compared, it was seen that the activity was moving distally with intestinal peristaltism. The reason for diagnostic imaging of the fistulas is not only to show the existence of the fistula but also locate it anatomically before the surgery. SPECT systems integrated with CT scanning provide functional and anatomical imaging at the same session. Dynamic renal scintigraphy and abdominal SPECT/CT, is a safe diagnostic procedure in visualization of urinary tract fistulas with advantages of the low cost, low radiation exposure and easier tolerability compared to double contrast imaging. CONFLICT OF INTEREST: None declared.

Avaliação de métodos radiográficos utilizados na localização vertical de sítios eleitos para instalação de mini-implantes / The accuracy of radiographic techniques used for vertical localization of mini-implants fixture placement

OBJETIVO: avaliar a efetividade de métodos de diagnóstico por imagem utilizados na localização vertical de sítios eleitos para inserção de mini-implantes. METODOLOGIA: a amostra foi composta de quatro pacientes, nos quais foram estabelecidos 32 sítios inter-radiculares, na região posterior, para instalação de mini-implantes, sítios estes representados por orifícios preenchidos com guta-percha em moldeiras de acetato (PCg - ponto de contato das coroas dentárias na moldeira de acetato; PIg - ponto de inserção do mini-implante na moldeira de acetato). Foram feitas radiografias periapicais, interproximais e tomografias computadorizadas de feixe cônico, com as moldeiras posicionadas em boca, sendo considerados os seguintes pontos: PC - imagem radiodensa do ponto PCg; PI - imagem radiodensa do ponto PIg; PCx - ponto de contato entre as coroas dentárias, determinado sobre a radiografia. Medidas verticais utilizadas: padrão-ouro - de PCg a PIg; medida 1 - de PC a PI; e medida 2 - de PCx a PI. As medidas foram comparadas através de análise descritiva e do teste t de Student. RESULTADOS: para a medida 1, foi observada diferença estatisticamente significante, em relação ao padrão-ouro, em 4,1 por cento, 25 por cento e 100 por cento das medidas avaliadas nas tomografias computadorizadas, radiografias interproximais e periapicais, respectivamente. Para a medida 2, foi observada diferença estatisticamente significante, em relação ao padrão-ouro, em 4,1 por cento, 56,2 por cento e 100 por cento das medidas avaliadas nas tomografias computadorizadas, radiografias interproximais e periapicais, respectivamente CONCLUSÕES: a tomografia computadorizada de feixe cônico foi o exame mais preciso na avaliação da posição vertical dos sítios eleitos para instalação de mini-implantes; a radiografia interproximal pode, com reserva, ser utilizada; a radiografia periapical apresentou resultados insatisfatórios, sendo contra-indicada para este fim.

OBJECTIVE: Evaluate the effectiveness of image diagnosis methods used in the vertical location of sites elect to insert mini-implants. METHODS: The sample was composed of four patients, in which 32 inter-radicular sites were established in the subsequent area, for setting up mini-implants. These sites were represented by holes filled out with guta-percha in acetate moulder (PCg - contact point of dental crowns in the acetate moulder; PIg - point of insertion of the mini-implant in the acetate moulder). Periapical X-rays, interproximal and computerized tomographies of cone-beam, with the moulders positioned in mouth, were performed and the following points were taken into consideration: PC - radiodense image of the PCg point; PI - radiodense image of the PIg point; PCx - contact point among the determined dental crowns on the X-ray. Vertical measures used: gold-pattern from PCg to PIg; measure 1 - from PC to PI; and measure 2 - from PCx to PI. The measures were compared through descriptive analysis and test t of Student. RESULTS: For the measure 1, differences statistically significant were observed (4.1 percent), in relation to the gold-pattern, 25 percent and 100 percent of the appraised measures in the computerized tomographies, interproximal and periapical X-rays, respectively. For the measure 2, differences statistically significant were observed in relation to the gold-pattern (4.1 percent), 56.2 percent and 100 percent of the appraised measures in the computerized tomographies, interproximal and periapical X-rays, respectively CONCLUSIONS: The cone-beam computerized tomography was the most precise exam in the evaluation of the vertical position of the elect sites to install mini-implants; the interproximal X-ray can, with reservation, be also used; the periapical X-ray presented unsatisfactory results, being contraindicated for this purpose.