Modeling boron adsorption on five soils before and after removal of organic matter

Boron- B concentrations that cause deficiency and those that cause toxicity appear to be very similar, compared to other nutrients, which can complicate successful management of this element in soils. In this study, B adsorption onto two Oxisols from Brazil (Rhodic Eutroperox and Anionic Acroperox), two Alfisols (Natric Palexeralf and Aridic Paleustalf) and an Entisol (Xeric Torrifluvent) from the United States of America were evaluated. The samples were treated with sodium hypochlorite in order to remove soil organic matter. Both treated and untreated samples were used to determine B adsorption isotherms using different B concentrations (0-4.630 mmol L–1) and NaNO3 (0.05 M) as background electrolyte solution at pH 7. Boron adsorption envelopes were also measured using 0.463 mmol L–1 B at three ionic strengths (0.05, 0.1 and 1M) and NaNO3 as background electrolyte solutions at different pH values (3-12). The cation exchange capacity, specific surface area, free Al and Fe oxides, organic and inorganic carbon content, mineralogy and particle size distribution of the soils were also determined. The Langmuir isotherm and the constant capacitance model were fit to the B adsorption data and the parameters obtained were related to the chemical attributes by multiple linear regression equations. Boron maximum adsorption capacity (BMAC) and the complexation constant for the SH3BO4inner-sphere complex (LogKB–) could be predicted under all experimental conditions. The Alc content was the main soil chemical attribute associated with the BMAC under the conditions evaluated and the LogKB–(int) in untreated and treated samples.(AU)

Modeling boron adsorption on five soils before and after removal of organic matter

Boron- B concentrations that cause deficiency and those that cause toxicity appear to be very similar, compared to other nutrients, which can complicate successful management of this element in soils. In this study, B adsorption onto two Oxisols from Brazil (Rhodic Eutroperox and Anionic Acroperox), two Alfisols (Natric Palexeralf and Aridic Paleustalf) and an Entisol (Xeric Torrifluvent) from the United States of America were evaluated. The samples were treated with sodium hypochlorite in order to remove soil organic matter. Both treated and untreated samples were used to determine B adsorption isotherms using different B concentrations (0-4.630 mmol L–1) and NaNO3 (0.05 M) as background electrolyte solution at pH 7. Boron adsorption envelopes were also measured using 0.463 mmol L–1 B at three ionic strengths (0.05, 0.1 and 1M) and NaNO3 as background electrolyte solutions at different pH values (3-12). The cation exchange capacity, specific surface area, free Al and Fe oxides, organic and inorganic carbon content, mineralogy and particle size distribution of the soils were also determined. The Langmuir isotherm and the constant capacitance model were fit to the B adsorption data and the parameters obtained were related to the chemical attributes by multiple linear regression equations. Boron maximum adsorption capacity (BMAC) and the complexation constant for the SH3BO4– inner-sphere complex (LogKB–) could be predicted under all experimental conditions. The Alc content was the main soil chemical attribute associated with the BMAC under the conditions evaluated and the LogKB–(int) in untreated and treated samples.

Telomere protein complexes and their role in lymphoid malignancies.

Telomeres are highly regulated and dynamic complexes that protect the genomic DNA and prevent the end of linear chromosomes from being misrecognized as a broken DNA. Due to the end replication problem, telomeres of somatic cells shorten with each cell division, inducing cell senescence. Telomerase is a reverse transcriptase capable of compensating telomere attrition by adding telomere repeats to the ends of chromosomes. Human telomeres are associated with the shelterin complex which consists of six telomere-associated proteins that specifically bind to telomeric DNA. Alterations or removal of individual shelterin components would lead to telomere uncapping and telomere dysfunction, resulting in cellular senescence and transformation to a malignant state. Another complex of multifunctional proteins, named non-shelterin complex, is thought to prevent telomere degradation and facilitate telomerase-based telomere elongation. As telomerase is highly expressed in most human tumor cells, it is considered an attractive target for new therapeutic strategies. In this review, we will summarize the characteristics of telomeres and telomerase in lymphoid malignancies and discuss the role of telomere-associated proteins in these entities.

Cholinergic Oculomotor Nucleus Activity Is Induced by REM Sleep Deprivation Negatively Impacting on Cognition.

Several efforts have been made to understand the involvement of rapid eye movement (REM) sleep for cognitive processes. Consolidation or retention of recognition memories is severely disrupted by REM sleep deprivation (REMSD). In this regard, pedunculopontine tegmental nucleus (PPT) and other brainstem nuclei, such as pontine nucleus (Pn) and oculomotor nucleus (OCM), appear to be candidates to take part in this REM sleep circuitry with potential involvement in cognition. Therefore, the objective of this study was to investigate a possible association between the performance of Wistar rats in a declarative memory and PPT, Pn, and OCM activities after different periods of REMSD. We examined c-Fos and choline acetyltransferase (ChaT) expressions as indicators of neuronal activity as well as a familiarity-based memory test. The animals were distributed in groups: control, REMSD, and sleep rebound (REB). At the end of the different REMSD (24, 48, 72, and 96 h) and REB (24 h) time points, the rats were immediately tested in the object recognition test and then the brains were collected. Results indicated that OCM neurons presented an increased activity, due to ChaT-labeling associated with REMSD that negatively correlated (r = -0.32) with the cognitive performance. This suggests the existence of a cholinergic compensatory mechanism within the OCM during REMSD. We also showed that 24 h of REMSD impacted similarly in memory, compared to longer periods of REMSD. These data extend the notion that REM sleep is influenced by areas other than PPT, i.e., Pn and OCM, which could be key players in both sleep processes and cognition.

Infection by Henneguya sp. (Myxozoa) in the bone tissue of the gill filaments of the Amazonian catfish Hypophthalmus marginatus (Siluriformes).

This study describes aspects of the infection caused by the myxosporean genus Henneguya, which forms cysts in the bony portion of the gill filaments of Hypophthalmusmarginatus. Specimens of this catfish were acquired dead from artisanal fishermen near the town of Cametá, state of Pará, northern Brazil, between July 2011 and May 2012. They were transported in refrigerated containers to the Carlos Azevedo Research Laboratory at the Federal Rural University of Amazonia, in Belém, where analyses were performed. After confirmation of parasitism by the genus Henneguya, observation were made using optical and differential interference contrast (DIC) microscopy. The histological technique of embedment in paraffin was used. Ziehl-Neelsen staining was applied to the histological sections. Necropsy analyses on specimens of H. marginatus showed that 80% of them (40/50) had cysts of whitish coloration inside the bony portion of the gill filaments, filled with Henneguya spores. The present study found inflammatory infiltrate in the vicinity of the cysts. Furthermore, the special Ziehl-Neelsen staining technique made it possible to mark the Henneguya sp. cysts in the bone tissue and in spore isolates in the gill tissue structure. The descriptions of these histopathological findings show that this parasite is very invasive and causes damage to its host tissues.

The critical illness polyneuropathy in septic patients with prolonged weaning from mechanical ventilation: is the diaphragm also affected? A pilot study.

BACKGROUND: Critical illness myopathy and/or neuropathy (CRIMYNE) is a common alteration seen in the ICU. The currently available bedside methods of measuring respiratory and peripheral muscle function in critically ill patients are somewhat inadequate. The objective of this study was to evaluate the presence of diaphragmatic and peripheral CRIMYNE in septic patients with prolonged weaning from mechanical ventilation (MV). METHODS: Cohort prospective study with an entry period of 6 months. In 2 Brazilian medical-surgical ICUs, septic patients ≥ 18 years of age, dependent on MV ≥ 14 days, requiring prolonged weaning from MV, awake (Richmond Agitation Sedation Scale ≥ -2), and with no previous history of polyneuropathy or myopathy were included. Electrophysiological studies of the limbs and also of the respiratory system by phrenic nerve conduction and needle electromyography of the diaphragm were performed in all subjects. RESULTS: Twelve subjects were enrolled during 6 months of study. The electrophysiological signs of peripheral CRIMYNE occurred in 9 subjects, 7 of whom died in the ICU. Three subjects developed critical illness polyneuropathy, 4 critical illness myopathy, and 2 both. Only one subject who developed peripheral CRIMYNE did not present diaphragmatic involvement, whereas no subject developed diaphragm involvement alone. Thus, electrophysiological signs of diaphragmatic CRIMYNE occurred in 8 of the 9 subjects with peripheral CRIMYNE. Upon clinical examination, 8 subjects were not able to moves their limbs against gravity, and these findings were related to the presence of peripheral and diaphragmatic dysfunction. CONCLUSIONS: Our pilot findings suggested that CRIMYNE is common in septic patients with prolonged weaning from MV (MV ≥ 14 d). The inability to move limbs against gravity is frequently associated with peripheral and diaphragmatic CRIMYNE, and the findings of CRIMYNE in peripheral electrophysiological tests are associated with diaphragmatic involvement.