Low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope: Monte Carlo treatment planning and dose measurements in a postmortem subject.

Objective.The goal of this study was to use Monte Carlo (MC) simulations and measurements to investigate the dosimetric suitability of an interventional radiology (IR) c-arm fluoroscope to deliver low-dose radiotherapy to the lungs.Approach.A previously-validated MC model of an IR fluoroscope was used to calculate the dose distributions in a COVID-19-infected patient, 20 non-infected patients of varying sizes, and a postmortem subject. Dose distributions for PA, AP/PA, 3-field and 4-field treatments irradiating 95% of the lungs to a 0.5 Gy dose were calculated. An algorithm was created to calculate skin entrance dose as a function of patient thickness for treatment planning purposes. Treatments were experimentally validated in a postmortem subject by using implanted dosimeters to capture organ doses.Main results.Mean doses to the left/right lungs for the COVID-19 CT data were 1.2/1.3 Gy, 0.8/0.9 Gy, 0.8/0.8 Gy and 0.6/0.6 Gy for the PA, AP/PA, 3-field, and 4-field configurations, respectively. Skin dose toxicity was the highest probability for the PA and lowest for the 4-field configuration. Dose to the heart slightly exceeded the ICRP tolerance; all other organ doses were below published tolerances. The AP/PA configuration provided the best fit for entrance skin dose as a function of patient thickness (R2 = 0.8). The average dose difference between simulation and measurement in the postmortem subject was 5%.Significance.An IR fluoroscope should be capable of delivering low-dose radiotherapy to the lungs with tolerable collateral dose to nearby organs.

Monte Carlo simulations and phantom validation of low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope.

PURPOSE: To use MC simulations and phantom measurements to investigate the dosimetry of a kilovoltage x-ray beam from an IR fluoroscope to deliver low-dose (0.3-1.0 Gy) radiotherapy to the lungs. MATERIALS AND METHODS: PENELOPE was used to model a 125 kV, 5.94 mm Al HVL x-ray beam produced by a fluoroscope. The model was validated through depth-dose, in-plane/cross-plane profiles and absorbed dose at 2.5-, 5.1-, 10.2- and 15.2-cm depths against the measured beam in an acrylic phantom. CT images of an anthropomorphic phantom thorax/lungs were used to simulate 0.5 Gy dose distributions for PA, AP/PA, 3-field and 4-field treatments. DVHs were generated to assess the dose to the lungs and nearby organs. Gafchromic film was used to measure doses in the phantom exposed to PA and 4-field treatments, and compared to the MC simulations. RESULTS: Depth-dose and profile results were within 3.2% and 7.8% of the MC data uncertainty, respectively, while dose gamma analysis ranged from 0.7 to 1.0. Mean dose to the lungs were 1.1-, 0.8-, 0.9-, and 0.8- Gy for the PA, AP/PA, 3-field, and 4-field after isodose normalization to cover âˆ¼ 95% of each lung volume. Skin dose toxicity was highest for the PA and lowest for the 4-field, and both arrangements successfully delivered the treatment on the phantom. However, the dose distribution for the PA was highly non-uniform and produced skin doses up to 4 Gy. The dose distribution for the 4-field produced a uniform 0.6 Gy dose throughout the lungs, with a maximum dose of 0.73 Gy. The average percent difference between experimental and Monte Carlo values were -0.1% (range -3% to +4%) for the PA treatment and 0.3% (range -10.3% to +15.2%) for the 4-field treatment. CONCLUSION: A 125 kV x-ray beam from an IR fluoroscope delivered through two or more fields can deliver an effective low-dose radiotherapy treatment to the lungs. The 4-field arrangement not only provides an effective treatment, but also significant dose sparing to healthy organs, including skin, compared to the PA treatment. Use of fluoroscopy appears to be a viable alternative to megavoltage radiation therapy equipment for delivering low-dose radiotherapy to the lungs.

A novel two-phase bioprocess for the production of Arthrospira (Spirulina) maxima LJGR1 at pilot plant scale during different seasons and for phycocyanin induction under controlled conditions.

A two-phase outdoor cultivation bioprocess for Arthrospira maxima LJGR1 combined with phycocyanin induction in concentrated cultures under controlled conditions was evaluated using a modified low-cost Zarrouk medium. Growth was monitored during 4 cycles in 2018 and 4 cycles in 2019. Biomass was harvested and concentrated using membrane technology at the end of each cycle for further phycocyanin induction using blue LED light (controlled conditions, 24 h). The highest biomass productivity was observed during spring and summer cycles (13.63-18.97 gDWm-2 d-1); during mid-fall and mid-end fall, a decrease was observed (9.93-7.76 gDWm-2 d-1). Under favorable growth conditions, phycocyanin induction was successful. However, during cycles with unfavorable growth condition, phycocyanin induction was not observed. Reactive-grade phycocyanin (3.72 ± 0.14) was recovered and purified using microfiltration and ultrafiltration technologies.

Biotransformation of water lettuce (Pistia stratiotes) to biohydrogen by Rhodopseudomonas palustris.

AIMS: Aim of the paper was to assess the feasibility of producing hydrogen as a biofuel by photofermentation of fermented water lettuce (Pistia stratiotes L.) waste biomass, after a nitrogen-stripping treatment. METHODS AND RESULTS: A natural (42OL) and an engineered strain (CGA676, with low-ammonium sensitivity) of Rhodopseudomonas palustris were used for producing hydrogen. The stripping procedure was highly effective for ammonium removal, with an acceptable selectivity (91% of ammonium was removed; only 14% of total organic acids were lost). Both strains were able to produce hydrogen only in the nitrogen-stripped substrate. The natural strain R. palustris 42OL showed a higher Biochemical Hydrogen Potential (1224 ml l-1 vs 720 ml l-1 ; 50·0 mol m-3 vs 29·4 mol m-3 ), but at a lower rate (5·6 ml l-1  h-1 vs 7·3 ml l-1  h-1 ; 0·23 mol m-3  h-1 vs 0·29 mol m-3  h-1 ) than strain CGA676. CONCLUSIONS: Water lettuce waste biomass can be used for biofuel production, after hydrolization, fermentation and nitrogen stripping. SIGNIFICANCE AND IMPACT OF THE STUDY: The investigation on novel, low cost and sustainable biomasses as feedstocks for biofuel production is a priority. Aquatic plants do not compete for arable land. Moreover, water lettuce is a floating and invasive weed, thus its biomass must be harvested when detrimental, and can now be biotransformed in clean hydrogen.

Biosorption of heavy metals influenced by the chemical composition of Spirulina sp. (Arthrospira) biomass.

The capacity of Spirulina sp. cells with different chemical composition for Pb (II), Cd (II) and Cr (VI) sorption, was evaluated. Four different types of Spirulina biomass with a different chemical composition were tested. Two of them contained a high percentage of protein (68.95 +/- 0.30 and 63.73 +/- 0.25%) as a result of being cultivated in Zarrouk medium and exposedat two light intensities (66 micromol photon m(-2) s(-1) and 144 micromol photon m(-2) s(-1)) in batch cultures. A third type of biomass, cultivated in a "Complex" medium and exposed at 66 micromol photon (m-2) s(-1), contained a high percentage of lipids (30.08 +/- 1.92. Finally, the fourth type of biomass was enriched in polysaccharides (25.54 +/- 0.51%) as a result of being cultivated in the "Complex" medium, but exposed at 144 micromol photon m(-2) s(-1). It was found that the chemical composition of Spirulina sp. cells did have a strong influence on their adsorption capacity. The maximum adsorption capacities (q(max)) for Pb and Cd were highest (172.41 and 54.05 mg g(-1) of cells, at pH 5.0 and 4.5 respectively) when cells exhibited the higher polysaccharide content. In the case of Cr VI, the highest q(max), was exhibited by cells cultivated in Zarrouk medium and showing the higher protein content (at pH 2.0). pH did not affect the adsorption of Pb II in the range of 3 to 5.5, nor of Cd in the range of 4 to 7. For Cr VI, adsorption was observed only at a pH equal to 2 or lower.

Fate of mucilage cell wall polysaccharides during coffee fermentation.

Effects of a 20-h fermentation on cell wall polysaccharides from the mucilage of pulped coffee beans were examined and compared to those of unfermented beans, on alcohol insoluble residues (AIRs), their hot-water-soluble crude pectic substances (PECTs), and their hot-water-insoluble residues (RESs). Yields and compositions were very similar: AIRs, which consisted of approximately 30% highly methylated pectic substances, approximately 9% cellulose, and approximately 15% neutral noncellulosic polysaccharides, exhibited no apparent degradation. However, PECTs from fermented beans were shown to have undergone a slight reduction of their intrinsic viscosity and weight-average molecular weight by capillary viscosimetry and high-performance size-exclusion chromatography. After fermentation, hot-water-insoluble pectic substances of RES exhibited partial de-esterification. Removal of coffee bean mucilage by natural fermentation seems to result from a restricted pectolysis, the mechanism of which remains to be elucidated.

Microbiological and biochemical study of coffee fermentation.

The coffee fermentation microflora were rich and mainly constituted of aerobic Gram-negative bacilli, with Erwinia and Klebsiella genuses at the highest frequencies. The best population increase was observed with lactic acid bacteria and yeasts, whereas those microorganisms that counted on a pectin medium remained constant during the fermentation step. Qualitatively, lactic acid bacteria belonged mainly to Leuconostoc mesenteroides species but the others microflora were relatively heterogeneous. The microorganisms isolated on pectin medium were Enterobacteriaceae, identified as Erwinia herbicola and Klebsiella pneumoniae, not reported as strong pectolytic strains. Throughout coffee fermentation, 60% of the simple sugars were degraded by the total microflora and not specifically by pectolytic microorganisms.

The effect of low light flux and nitrogen deficiency on the chemical composition of Spirulina sp. (Arthrospira) grown on digested pig waste.

Evaluation of the effect of low light flux and nitrogen deficiency on growth and chemical composition of Spirulina sp. (straight filaments strain, SF) in batch cultures utilizing a complex medium containing sea-water supplemented with anaerobic effluents from digested pig waste, was undertaken. Cultivation was carried out either at a light flux of 66 (lower) or 144 micromol photon m(-2) s(-1) (higher), utilizing bench raceways. Biomass concentration (as dry weight) after 12 days of cultivation in the complex medium was similar (P < 0.05) to the one observed in a chemically defined medium (Zarrouk), regardless of the light intensity. Protein content of the biomass in the complex medium was significantly lower (P < 0.05), compared to the Zarrouk medium, regardless of the light flux. However, biomass from the complex medium was enriched in total lipids (28.6%), when cultures were exposed to the lower light flux. On the other hand, the palmitoleic acid percentage of total fatty acids was significantly higher (P < 0.05) at a higher light intensity and a high level of gamma linolenic acid (GLA) as a percentage of total fatty acids was observed (28.13%) in the biomass harvested from the complex medium at the lower light intensity. Finally, polysaccharide content was significantly higher (P < 0.05) at the high light intensity and a very high content of total polysaccharides (28.41%) was observed in the complex medium.

Accelerated coffee pulp composting.

The effect of two abundant, easily available and very low-cost agro-industrial organic residues, i.e., filter cake from the sugar industry and poultry litter, on the composting stabilization time of coffee pulp and on the quality of the produced compost, was evaluated. Piles of one cubic meter were built and monitored within the facilities of a coffee processing plant in the Coatepec region of the State of Veracruz, Mexico. Manual aeration was carried out once a week. A longer thermophilic period (28 days) and a much lower C/N ratio (in the range of 6.9-9.1) were observed in the piles containing the amendments, as compared to the control pile containing only coffee pulp (14 days and a C/N ratio of 14.4, respectively). The maximum assimilation rate of the reducing sugars was 1.6 g kg-1 d-1 (from 7.5 to 5.3%) during the first two weeks when accelerators were present in the proportion of 20% filter cake plus 20% poultry litter, while they accumulated at a rate of 1.2 g kg-1 d-1 (from 7.4 to 9.13%) during the same period in the control pile. The best combination of amendments was 30% filter cake with 20% poultry litter, resulting in a final nitrogen content as high as 4.81%. The second best combination was 20% filter cake with 10% poultry litter, resulting in a compost which also contained a high level of total nitrogen (4.54%). It was concluded that the use of these two residues enhanced the composting process of coffee pulp, promoting a shorter stabilization period and yielding a higher quality of compost.

Simultaneous high-biomass protein production and nutrient removal using Spirulina maxima in sea water supplemented with anaerobic effluents.

Maximum protein accumulation (71%, w/w) and nutrient removal by a mutant strain of Spirulina maxima growing on sea water supplemented with anaerobically treated pig slurry was achieved at 30°C with constant illumination (60 to 70 µEm(-2)s(-1)), using a flow rate of 14.5 cm s(-1) (20 rev. min(-1) of a paddle wheel). Total phosphates were decreased by 99% and all ammonia-N was removed under these conditions.

Accelerated food waste composting.

Experiments on food waste composting under the temperate and dry conditions of Mexico City showed that the waste stabilized faster (within 2 months) if an 'accelerator' (chopped orange peel and carrot bagasse) was used. The relatively cool and humid conditions prevailing during similar experiments in Xalapa City inhibited decomposition, and stabilization of waste, with or without accelerator, was generally slower than in Mexico City. However, addition of wood chips as a bulking agent greatly improved composting in Xalapa, leading to stabilization in just 35 days.Use of the accelerator increases the initial C/N ratio in the waste. This permits rapid utilization of any easily degradable sugars, which in turn supports rapid multiplication of mesophilic microorganisms.

Xeroderma pigmentoso. / Xeroderma pigmentosum

Se presenta un caso clinico de xeroderma pigmentoso diagnosticado en una nina de 3 anos y medio, la que consulto por tumores malignos faciales de tipo epitelioma basocelular; hiperpigmentacion cutanea; ectropion bilateral; conjuntivitis y fotofobia.La paciente que ahora tiene 4 anos y 9 meses, ha sido operada en 6 oportunidades, extirpandosele los tumores faciales, cuyo estudio histopatologico demostro que correspondian a carcinomas pavimentosos de tipo basocelular. Ademas de la cirugia, ha sido tratada con indometacina y con aplicaciones topicas de 5 fluorouracilo. Actualmente la paciente continua en tratamiento y bajo control. Se aprovecha el caso para hacer: una revision del xeroderma pigmentoso en relacion a etiologia, fisiopatologia, sintomatologia, diagnostico y tratamiento, haciendo hincapie en los aspectos preventivos

Sindrome del nino agredido. Actitud del pediatra en la practica clinica. / The abused child syndrome. Attitude of the pediatrician in clinical practice

El sindrome del nino agredido es un concepto muy amplio que incluye dano moral, psicologico y fisico. El abuso de ninos es frecuente en nuestro medio, aunque es relativamente desconocido entre los medicos y no hay criterios medico-forenses al respecto. La ley obliga al pediatra a denunciar los casos sospechosos de agresion a un nino. El medico que no denuncie estos casos cae en pena legal. El hecho debe ser informado aun en caso de ser sospecha, basada en la historia o en los hallazgos clinicos. Si la sospecha no es confirmada la Ley protege al medico de demandas civiles por esta causa, estimando que el facultativo ha obrado de buena fe