Evolução das doses no ambiente do Reator IEA-R1 e tendências com base nos resultados atuais

O Ipen/Cnen-SP possui um Reator de Pesquisa(IEA-R1) em operação desde 1957. Ele utiliza água leve como blindagem, moderador e como fluido refrigerante, o volume desta piscina é de 273m3. Até 1995 a operação do Reator era descontinua, ou seja, operava diariamente sendo desligado no final do dia, a uma potência de 2,0 MW. A partir daquele ano, após algumas modificações de segurança, o Reator passou a operar de forma continua, ou seja, de segunda-feira a quarta-feira sem ser desligado, totalizando 64 horas semanais. A potência também foi aumentando até 4,5 MW em 2012. Em virtude dessas alterações, a saber, operação contínua e do aumento da potência, as doses dos trabalhadores aumentaram e por isso foram realizados vários estudos para diminui-las. Estudos demonstraram que uma das principais limitações para operação de um reator em potência elevada, provém das radiações gama emitidas pelo sódio-24. Outros elementos como magnésio-27, Alumínio-28, Argônio-51, contribuem de forma considerável para a atividade da água da piscina. A introdução de uma camada de água quente em sua superfície, estável e isenta de elementos radioativos com 1,5m a 2m de espessura constituiria uma blindagem às radiações provenientes dos elementos radioativos dissolvidos na água. Estudos de otimização provaram que a instalação da camada quente não era necessária para o regime e potência atual de operação do Reator, pois outros procedimentos adotados eram mais eficazes. A partir desta decisão o serviço de Proteção Radiológica do Reator IEA-R1, montou um programa de avaliação das doses para certificar-se de que elas se mantinham em valores razoáveis baseados em princípios estabelecidos em normas nacionais e internacionais. O intuito deste trabalho é realizar uma análise das doses individuais dos IOE (Individuo Ocupacionalmente Expostos), considerando as mudanças no regime de operação do Reator e sugerir opções de proteção e segurança, viáveis em primeira instância, para reduzir as doses analisadas, visando se chegar aos níveis de referencia de 3 mSv/ano adotados pela instalação em apreço.

Análise do aporte de sódio sob a forma de pão, numa população idosa institucionalizada

"Introdução: O pão tem sido apontado como um alimento relevante no aporte total de sódio de algumas populações. Em 2009 em Portugal, o consumo anual de pão per capita foi cerca de 70 kg. As atuais recomendações de aporte de sal são quase sempre excedidas, sendo este facto mais grave em indivíduos idosos e hipertensos. Objetivo: Avaliar a contribuição do consumo de pão no aporte total de sódio diário em idosos institucionalizados e avaliar junto da instituição em pesquisa, o potencial efeito e o cumprimento da lei n.º 75/2009 com entrada em vigor a 12 de Agosto de 2010."

Independent relations of left ventricular structure with the 24-hour urinary excretion of sodium and aldosterone.

Previous studies reported on the association of left ventricular mass index (LVMI) with urinary sodium or with circulating or urinary aldosterone. We investigated the independent associations of LVMI with the urinary excretion of both sodium and aldosterone. We randomly recruited 317 untreated subjects from a white population (45.1% women; mean age 48.2 years). Measurements included echocardiographic left ventricular (LV) properties, the 24-hour urinary excretion of sodium and aldosterone, plasma renin activity (PRA), and proximal (RNa(prox)) and distal (RNa(dist)) renal sodium reabsorption, assessed from the endogenous lithium clearance. In multivariable-adjusted models, we expressed changes in LVMI per 1-SD increase in the explanatory variables, while accounting for sex, age, systolic blood pressure, and the waist-to-hip ratio. LVMI increased independently with the urinary excretion of both sodium (+2.48 g/m(2); P=0.005) and aldosterone (+2.63 g/m(2); P=0.004). Higher sodium excretion was associated with increased mean wall thickness (MWT: +0.126 mm, P=0.054), but with no change in LV end-diastolic diameter (LVID: +0.12 mm, P=0.64). In contrast, higher aldosterone excretion was associated with higher LVID (+0.54 mm; P=0.017), but with no change in MWT (+0.070 mm; P=0.28). Higher RNa(dist) was associated with lower relative wall thickness (-0.81x10(-2), P=0.017), because of opposite trends in LVID (+0.33 mm; P=0.13) and MWT (-0.130 mm; P=0.040). LVMI was not associated with PRA or RNa(prox.) In conclusion, LVMI independently increased with both urinary sodium and aldosterone excretion. Increased MWT explained the association of LVMI with urinary sodium and increased LVID the association of LVMI with urinary aldosterone.

Independent relations of left ventricular structure with the 24-h urinary excretion of sodium and aldosterone

Objective: Previous studies reported on the association of left ventricular mass index (LVMI) with urinary sodium or with circulating or urinary aldosterone.We investigated the independent associations of LVMI with the urinary excretion of both sodium and aldosterone. Design and method: We randomly recruited 317 untreated subjects from a White population (45.1%women; mean age 48.2 years).Measurements included echocardiographic left ventricular (LV) properties, the 24 h urinary excretion of sodium and aldosterone, plasma renin activity (PRA), and proximal (RNaprox) and distal (RNadist) renal sodium reabsorption, assessed fromthe endogenous lithium clearance. Inmultivariable-adjusted models,we expressed changes in LVMI per 1 SD increase in the explanatory variables, while accounting for sex, age, systolic blood pressure and the waist-to-hip ratio. Results: LVMI increased independentlywith the urinary excretion of both sodium (+2.48 g/m2; P=0.005) and aldosterone (+2.63 g/m2; P=0.004). Higher sodium excretion was associated with increased mean wall thickness (MWT: +0.126 mm, P=0.054), but with no change in LV end-diastolic diameter (LVID: +0.12mm, P=0.64). In contrast, higher aldosterone excretion was associated with higher LVID (+0.54 mm; P=0.017), but with no change in MWT (+0.070mm; P=0.28).Higher RNadistwas associatedwith lower relativewall thickness (−0.81×10−2, P=0.017), because of opposite trends in LVID(+0.33 mm; P=0.13) and MWT (−0.130mm; P=0.040). LVMI was not associated with PRA or RNaprox. Conclusions: LVMI independently increased with both urinary sodium and aldosterone excretion. IncreasedMWT explained the association of LVMI with urinary sodium and increased LVID the association of LVMI with urinary aldosterone.

Correlation between sodium and potassium excretion in 24- and 12-h urine samples

Low-sodium and high-potassium diets have been recommended as an adjunct to prevention and treatment of hypertension. Analysis of these nutrients in 24-h urine has been considered the reference method to estimate daily intake of these minerals. However, 24-h urine collection is difficult in epidemiological studies, since urine must be collected and stored in job environments. Therefore, strategies for shorter durations of urine collection at home have been proposed. We have previously reported that collecting urine during a 12-h period (overnight) is more feasible and that creatinine clearance correlated strongly with that detected in 24-h samples. In the present study, we collected urine for 24 h divided into two 12-h periods (from 7:00 am to 7:00 pm and from 7:00 pm to 7:00 am next day). A sample of 109 apparently healthy volunteers aged 30 to 74 years of both genders working in a University institution was investigated. Subjects with previous myocardial infarction, stroke, renal insufficiency, and pregnant women were not included. Significant (P < 0.001) Spearman correlation coefficients (r s) were found between the total amount of sodium and potassium excreted in the urine collected at night and in the 24-h period (r s = 0.76 and 0.74, respectively). Additionally, the 12-h sodium and potassium excretions (means ± SD, 95% confidence interval) corresponded to 47.3 ± 11.2%, 95%CI = 45.3-49.3, and 39.3 ± 4.6%, 95%CI = 37.3-41.3, respectively, of the 24-h excretion of these ions. Therefore, these findings support the assumption that 12-h urine collected at night can be used as a reliable tool to estimate 24-h intake/excretion of sodium and potassium.

Productive performance and milk protein fraction composition of dairy cows supplemented with sodium monensin

The objective of this work was to evaluate the levels of sodium monensin on lactating cows and their effects on productive performance and milk protein fraction composition. It was used 12 Holstein cows, distributed in four balanced 3 × 3 Latin squares, and fed three diets: one control without monensin, and two diets with monensin at the levels of 24 or 48 mg/kg DM added to the concentrate. Milk production was daily measured throughout the entire experimental period. The samples used for analysis of milk composition were collected on two alternated days from the two daily milking. Non-protein nitrogen, total nitrogen and non-casein nitrogen contents were directly evaluated in the milk, and casein, whey protein and true protein contents were indirectly determined. The use of monensin in the rations reduced dry matter and nutrient intake, especially when diet with 48 mg/kg of dry matter was given. The ration with 24 mg/kg of DM increased milk production, with or without correction, and also fat and lactose yield, and it improved productive efficiency. The levels of monensin in the ratios did not influence contents of milk crude protein, non-protein nitrogen, non-casein nitrogen, true protein, casein, casein/true protein ratio, whey protein, and of all those fractions expressed as percentage of crude protein. The utilization of monensin in the ratio at the dose of 24 mg/kg of DM influences positively the productive performance of lactating cows, and it does not influence the composition of milk protein fractions.

A Randomized Trial of Sodium Fluoride (60 mg) ± Estrogen in Postmenopausal Osteoporotic Vertebral Fractures

Postmenopausal Caucasian women aged less than 80 years (n = 99) with one or more atraumatic vertebral fracture and no hip fractures, were treated by cyclical administration of enteric coated sodium fluoride (NaF) or no NaF for 27 months, with precautions to prevent excessive stimulation of bone turnover. In the first study 65 women, unexposed to estrogen (-E study), age 70.8 +/- 0.8 years (mean SEM) were all treated with calcium (Ca) 1.0-1.2 g daily and ergocalciferol (D) 0.25 mg per 25 kg once weekly and were randomly assigned to cyclical NaF (6 months on. 3 months off, initial dose 60 mg/day; group F CaD, n = 34) or no NaF (group CaD, n = 3 1). In the second study 34 patients. age 65.5 +/- 1.2 years, on hormone replacement therapy (E) at baseline, had this standardized, and were all treated with Ca and D and similarly randomized (FE CaD, n = 17, E CaD, n = 17) (+E study). The patients were stratified according to E status and subsequently assigned randomly to NaF. Seventy-five patients completed the trial. Both groups treated with NaF showed an increase in lumbar spinal density (by DXA) above baseline by 27 months: FE CaD + 16.2% and F CaD +9.3% (both p = 0.0001). In neither group CaD nor E CaD did lumbar spinal density increase. Peripheral bone loss occurred at most sites in the F CaD group at 27 months: tibia/fibula shaft -7.3% (p = 0.005); femoral shaft -7.1% (p = 0.004); distal forearm -4.0% (p = 0.004); total hip -4.1% (p = 0. 003); and femoral neck -3.5% (p = 0.006). No significant loss occurred in group FE CaD. Differences between the two NaF groups were greatest at the total hip at 27 months but were not significant [p < 0.05; in view of the multiple bone mineral density (BMD) sites, an alpha of 0.01 was employed to denote significance in BMD changes throughout this paper]. Using Cox's proportional hazards model, in the -E study there were significantly more patients with first fresh vertebral fractures in those treated with NaF than in those not so treated (RR = 24.2, p = 0.008, 95% CI 2.3-255). Patients developing first fresh fractures in the first 9 months were markedly different between groups: -23% of F CaD, 0 of CaD, 29% of FE CaD and 0 of E CaD. The incidence of incomplete (stress) fractures was similar in the two NaF-treated groups. Complete nonvertebral fractures did not occur in the two +E groups, there were no differences between groups F CaD and CaD. Baseline BMD (spine and femoral neck) was related to incident vertebral fractures in the control groups (no NaF), but not in the two NaF groups. Our results and a literature review indicate that fluoride salts. if used, should be at low dosage, with pretreatment and co-treatment with a bone resorption inhibitor.

Sodium channel alpha 1-subunit mutations in severe myoclonic epilepsy of infancy and infantile spasms

Background: Mutations in SCN1A, the gene encoding the alpha1 subunit of the sodium channel, have been found in severe myoclonic epilepsy of infancy (SMEI) and generalized epilepsy with febrile seizures plus (GEFS(+)). Mutations in SMEI include missense, nonsense, and frameshift mutations more commonly arising de novo in affected patients. This finding is difficult to reconcile with the family history of GEFS(+) in a significant proportion of patients with SMEI Infantile spasms (IS), or West syndrome, is a severe epileptic encephalopathy that is usually symptomatic. In some cases, no etiology is found and there is a family history of epilepsy. Method: The authors screened SCN1A in 24 patients with SMEI and 23 with IS. Results: Mutations were found in 8 of 24 (33%) SMEI patients, a frequency much lower than initial reports from Europe and Japan. One mutation near the carboxy terminus was identified in an IS patient. A family history of seizures was found in 17 of 24 patients with SMEI. Conclusions: The rate of SCN1A mutations in this cohort of SMEI patients suggests that other factors may be important in SMEI. Less severe mutations associated with GEFS(+) could interact with other loci to cause SMEI in cases with a family history of GEFS(+). This study extends the phenotypic heterogeneity of mutations in SCN1A to include IS.

Association of low sodium-iodide symporter messenger ribonucleic acid expression in malignant thyroid nodules with increased intracellular protein staining

Context: The expression of sodium iodide symporter (NIS) is required for iodide uptake in thyroid cells. Benign and malignant thyroid tumors have low iodide uptake. However, previous studies by RT-PCR or immunohistochemistry have shown divergent results of NIS expression in these nodules. Objective: The objective of the study was to investigate NIS mRNA transcript levels, compare with NIS and TSH receptor proteins expression, and localize the NIS protein in thyroid nodules samples and their surrounding nonnodular tissues (controls). Design: NIS mRNA levels, quantified by real-time RT-PCR, and NIS and TSH receptor proteins, evaluated by immunohistochemistry, were examined in surgical specimens of 12 benign and 13 malignant nodules and control samples. Results: When compared with controls, 83.3% of the benign and 100% of the malignant nodules had significantly lower NIS gene expression. Conversely, 66.7% of the benign and 100% of malignant nodules had stronger intracellular NIS immunostaining than controls. Low gene expression associated with strong intracellular immunostaining was most frequently detected in malignant (100%) than benign nodules (50%; P = 0.005). NIS protein was located at the basolateral membrane in 24% of the control samples, 8.3% of the benign, and 15.4% of the malignant nodules. The percentage of benign nodules with strong TSH receptor positivity (41.6%) was higher than malignant (7.7%). Conclusion: We confirmed that reduced NIS mRNA expression in thyroid malignant nodules is associated with strong intracellular protein staining and may be related to the inability of the NIS protein to migrate to the cellular basolateral membrane. These results may explain the low iodide uptake of malignant nodules.

Spontaneous reversibility of damage to outer hair cells after sodium salicylate induced ototoxicity

Background: High sodium salicylate doses can cause reversible hearing loss and tinnitus, possibly due to reduced outer hair cell electromotility. Sodium salicylate is known to alter outer hair cell structure and function. This study determined the reversibility and cochlear recovery time after administration of an ototoxic sodium salicylate dose to guinea pigs with normal cochlear function. Study design: Prospective experimental investigation. Methods: All animals received a single 500 mg sodium salicylate dose, but with different durations of action. Function was evaluated before drug administration and immediately before sacrifice. Cochleae were processed and viewed using scanning electron microscopy. Results: Changes in outer hair cell function were observed to be present 2 hours after drug administration, with recovery of normal anatomy beginning after 24 hours. Subsequently, derangement and distortion of cilia reduced, with effects predominantly in row three. At 168 hours, cilia were near-normal but with mild distortions which interfered with normal cochlear physiology. Conclusions: Ciliary changes persisted for up to 168 hours after ototoxic sodium salicylate administration.

Effect of the Combination of Sodium Hypochlorite and Chlorhexidine on Dentinal Permeability and Scanning Electron Microscopy Precipitate Observation

Introduction: This study compared the combined use of sodium hypochlorite (NaOCl) and chlorhexidine (CXH) with citric acid and CXH on dentinal permeability and precipitate formation. Methods: Thirty-four upper anterior teeth were prepared by rotary instrumentation and NaOCl. The root canal surfaces were conditioned for smear layer removal using 15% citric acid solution under ultrasonic activation and a final wash with distilled water. All teeth were dried, and 30 specimens were randomly divided into three equal groups as follows: positive control group (PC), no irrigation; 15% citric acid + 2% CHX group (CA + CHX); and 1% NaOCl + 2% CHX group (NaOCl + CHX). All roots were immersed in a 0.2% Rhodamine B solution for 24 hours. One-millimeter-thick slices from the cementum-enamel junction were scanned at 400 dpi and analyzed using the software ImageLab (LIDO-USP, Sao Paulo, Brazil) for the assessment of leakage in percentage. For scanning electron microscopy analysis, four teeth, irrigated for NaOCl + CHX samples, were split in half, and each third was evaluated at 1,000x and 5,000x (at the precipitate). Results: Using the analysis of variance test followed by the Bonferroni comparison method, no statistical differences between groups were found when analyzed at the cervical and medium thirds. At the apical third, differences between the PC and NaOCl + CHX (p<0.05) and CA + CHX and NaOCl + CHX could be seen (p < 0.05). Conclusion: The combination of 1% NaOCl and 2% CHX solutions results in the formation of a flocculate precipitate that acts as a chemical smear layer reducing the dentinal permeability in the apical third. (J Endod 2010;36:847-850)

The effect of sodium chloride supplementation on the milk production of grazing Holstein Friesian cows during summer and autumn in a humid sub-tropical environment

Two studies were conducted to examine the effects of including NaCl at various rates in grain-based supplements for Friesian cows grazing established, dominant (>90%), rainfed kikuyu (Pennisetum clandestinum cv. Common) pastures during summer and autumn in a humid sub-tropical environment. In study 1 (19 January-27 March 1998), 48 cows (36 multiparous, 12 primiparous; 27-96 days postpartum) were allocated to one of four groups based on genetic merit, milk production, liveweight (LW) and days postpartum. They were fed (2.7 kg dry matter (DM) per cow, twice-a-day) one of four isoenergetic and isonitrogenous barley grain-based concentrates containing NaCl at concentrations (% as-fed) of either 0 (SC1), 1.1 (SC2), 2.2 (SC3) or 3.3 (SC4). Maximum temperature humidity index (THImax) was greater than or equal to78 during 50% of the experimental period. Concentrate NaCl content had no effect (P>0.05) on daily milk yield or LW change but daily yields of 4% fat corrected milk (FCM), fat and protein were higher (P0.05) among treatments at 7.6+/-1.24 kg DM per cow. In study 2 (18 January 1999-1 March 1999), 48 cows (32 pluriparous, 16 primiparous: 32-160 days postpartum) were fed (2.7 kg DM per cow twice-a-day) one of two isoenergetic and isonitrogenous barley grain-based concentrates containing NaCl at concentrations (% as-fed) of 0 (control) or 2.2 (HSC). THImax was greater than or equal to78 during 34% of days in the experimental period. Yields of milk, FCM, fat and protein were lower (P0.05) by concentrate NaCl content. These studies indicate that NaCl supplementation can be beneficial in terms of milk production during warm, humid conditions as opposed to milder conditions. (C) 2002 Elsevier Science B.V. All rights reserved.

Sensitivity of Helicoverpa armigera nucleopolyhedrovirus polyhedra to sodium dodecyl sulfate

Sodium dodecyl sulfate (SDS) is commonly used to extract polyhedra from infected cells and diseased dead larval tissues. It was found, however, that 80% of Helicoverpa armigera nucleopolyhedrovirus (HaSNPV) polyhedra produced via cell culture were damaged after 30 min of 0.5% SDS treatment whereas only 20% of in vivo produced polyhedra were damaged by the same treatment. Transmission and scanning electron microscopy revealed that the damaged polyhedra had lost their polyhedron envelopes and virions were dislodged from the polyhedrin matrix, leaving empty spaces that were previously occupied by the occluded virions. Up to 20% in vitro produced polyhedra were resistant to SDS and remained intact, even after a 24 h exposure to SDS. This sensitivity to SDS was observed across a range of cell culture media, including serum supplemented media. Electron microscopy also revealed that the inferior polyhedron envelope of in vitro produced polyhedra is likely due to poor interaction between the polyhedron envelope, polyhedron envelope protein (PEP), and polyhedrin matrix. The PEP gene was cloned and sequenced and mutations in this gene were ruled out as an explanation. In vitro produced polyhedra that were passed through insect larva once were resistant to SDS, indicating that a critical component is lacking in insect cell culture medium used for producing HaSNPV or the cells growing in culture are inefficient in some ways in relation to production of polyhedra. (C) 2002 Elsevier Science (USA). All rights reserved.