Subtle white matter intensity changes on fluid-attenuated inversion recovery imaging in patients with ischaemic stroke.

Leukoaraiosis is a neuroimaging marker of small-vessel disease that is characterized by high signal intensity on fluid-attenuated inversion recovery MRI. There is increasing evidence from pathology and neuroimaging suggesting that the structural abnormalities that characterize leukoaraiosis are actually present within regions of normal-appearing white matter, and that the underlying pathophysiology of white matter damage related to small-vessel disease involves blood-brain barrier damage. In this study, we aim to verify whether leukoaraiosis is associated with elevated signal intensity on fluid-attenuated inversion recovery imaging, a marker of brain tissue free-water accumulation, in normal-appearing white matter. We performed a cross-sectional study of adult patients admitted to our hospital with a diagnosis of acute ischaemic stroke or transient ischaemic attack. Leukoaraiosis was segmented using a semi-automated method involving manual outlining and signal thresholding. White matter regions were segmented based on the probabilistic tissue maps from the International Consortium for Brain Mapping 152 atlas. Also, normal-appearing white matter was further segmented based on voxel distance from leukoaraiosis borders, resulting in five normal-appearing white matter strata at increasing voxel distances from leukoaraiosis. The relationship between mean normalized fluid-attenuated inversion recovery signal intensity on normal-appearing white matter and leukoaraiosis volume was studied in a multivariable statistical analysis using linear mixed modelling, having normal-appearing white matter strata as a clustering variable. One hundred consecutive patients meeting inclusion and exclusion criteria were selected for analysis (53% female, mean age 68 years). Mean normalized fluid-attenuated inversion recovery signal intensity on normal-appearing white matter was higher in the vicinity of leukoaraiosis and progressively lower at increasing distances from leukoaraiosis. In a multivariable analysis, the mean normalized fluid-attenuated inversion recovery signal intensity on normal-appearing white matter was positively associated with leukoaraiosis volume and age (B = 0.025 for each leukoaraiosis quartile increase; 95% confidence interval 0.019-0.030). This association was found similarly across normal-appearing white matter strata. Voxel maps of the mean normalized fluid-attenuated inversion recovery signal intensity on normal-appearing white matter showed an increase in signal intensity that was not adjacent to leukoaraiosis regions. Our results show that normal-appearing white matter exhibits subtle signal intensity changes on fluid-attenuated inversion recovery imaging that are related to leukoaraiosis burden. These results suggest that diffuse free-water accumulation is likely related to the aetiopathogenic processes underlying the development of white matter damage related to small-vessel disease.

Neurite orientation dispersion and density imaging in cocaine use disorder.

Cocaine use disorder (CUD) is characterized by a compulsive search for cocaine. Several studies have shown that cocaine users exhibit cognitive deficits, including lack of inhibition and decision-making as well as brain volume and diffusion-based white-matter alterations in a wide variety of brain regions. However, the non-specificity of standard volumetric and diffusion-tensor methods to detect structural micropathology may lead to wrong conclusions. To better understand microstructural pathology in CUD, we analyzed 60 CUD participants (3 female) and 43 non-CUD controls (HC; 2 female) retrospectively from our cross-sectional Mexican SUD neuroimaging dataset (SUDMEX-CONN), using multi-shell diffusion-weighted imaging and the neurite orientation dispersion and density imaging (NODDI) analysis, which aims to more accurately model microstructural pathology. We used Viso values of NODDI that employ a three-compartment model in white (WM) and gray-matter (GM). These values were also correlated with clinical measures, including psychiatric severity status, impulsive behavior and pattern of cocaine and tobacco use in the CUD group. We found higher whole-brain microstructural pathology in WM and GM in CUD patients than controls. ROI analysis revealed higher Viso-NODDI values in superior longitudinal fasciculus, cingulum, hippocampus cingulum, forceps minor and Uncinate fasciculus, as well as in frontal and parieto-temporal GM structures. We also found correlations between significant ROI and impulsivity, onset age of cocaine use and weekly dosage with Viso-NODDI. However, we did not find correlations with psychopathology measures. Overall, although their clinical relevance remains questionable, microstructural pathology seems to be present in CUD both in gray and white matter.

Seasonal changes in primary production and respiration in a subtropical lake undergoing eutrophication.

The balance between gross primary production (GPP) and respiration (R) is frequently used to estimate the role of lakes in the carbon cycle. Seasonal changes in the carbon cycle of subtropical lakes are often underestimated, but changes in meteorological and limnological characteristics often follow the well-defined climatic seasons. Based on 1 year's free-water dissolved oxygen and temperature measurements, we investigated the seasonal changes in primary production and respiration in subtropical Peri Lake in Southern Brazil, which is currently undergoing eutrophication. We expected that periods of high light availability and temperature would lead to a net autotrophic condition. Furthermore, we explored the seasonal coupling between GPP and R, expecting that different sources of organic matter would have different effects on the metabolic rates. We found that Peri Lake was predominately net heterotrophic (GPP < R). GPP was high during summer and autumn and low in winter, as was R, coinciding with the seasonal changes occurring in light and temperature. Light conditions were of essential importance for the variations in GPP, while respiration was fueled by both autochthonous and allochthonous organic matter. Constant external input of organic matter resulted in a generally low coupling between GPP and R. A tighter coupling between GPP and R was observed in spring as a result of higher productivity, while a decoupling in autumn was due to intensified allochthonous organic matter runoff caused by rainfall and wind. We found that higher productivity rates in summer did not shift the system to an autotrophic condition and that Peri Lake functioned as a carbon source, light and organic matter being the prime drivers for the metabolic rates.

Impact of the Hydration States of Polymers on Their Hemocompatibility for Medical Applications: A Review.

Water has a key role in the functioning of all biological systems, it mediates many biochemical reactions, as well as other biological activities such as material biocompatibility. Water is often considered as an inert solvent, however at the molecular level, it shows different behavior when sorbed onto surfaces like polymeric implants. Three states of water have been recognized: non-freezable water, which does not freeze even at -100 °C; intermediate water, which freezes below 0 °C; and, free water, which freezes at 0 °C like bulk water. This review describes the different states of water and the techniques for their identification and quantification, and analyzes their relationship with hemocompatibility in polymer surfaces. Intermediate water content higher than 3 wt % is related to better hemocompatibility for poly(ethylene glycol), poly(meth)acrylates, aliphatic carbonyls, and poly(lactic-co-glycolic acid) surfaces. Therefore, characterizing water states in addition to water content is key for polymer selection and material design for medical applications.

Effect of variations in the nitrogen loading rate and seasonality on the operation of a free water surface constructed wetland for treatment of swine wastewater.

The aim of this study was to evaluate the effects of variations in the nitrogen loading rate (NLR) and seasonality on the operational efficiency of a free-water surface constructed wetland (FWS) and on the processes involved in total nitrogen (TN) removal in treating swine wastewater. The system, which operated for 550 days, consisted of a FWS mesocosm inoculated with Typha angustifolia L., using swine wastewater from a storage lagoon as an influent. After operating with nitrogen loading rates (NLRs) of 2.0 to 30.2 kg TN ha(-1)·d(-1), the FWS reduced total nitrogen (TN) concentration by between 21.6 and 51.0%, achieving maximum removal (48.2 ± 3.0%) when the system operated at a NLR below 15.0 kg TN ha(-1)·d(-1). Moreover, operations over 25.0 kg TN ha(-1)·d(-1) resulted in a 50.6% decrease in the maximum FWS efficiency, which may have been related to increased anoxic conditions (< 0.5 mg O2 L(-1); -169.8 ± 70.3 mV) resulting from the high concentration of organic matter in the system (12.3 ± 10.5 g TCOD L(-1)), which hindered nitrification. Ammonia volatilization is considered the main method to remove TN, with an average value of 14.4 ± 6.5% (3.1-26.2%). Maximum volatilization occurred during the summer (21.5 ± 2.4°C) at an NLR higher than 25 kg TN ha(-1)·d(-1) (26.6%), favored by higher temperatures (17.3-19.7°C), and high NH4(+)-N (>600.0 9 mg NH4(+)-N L(-1)) and pH levels (7.1-7.9). Uptake by plants accounted for 14.9% of the TN removed, with the vegetative peak in summer (height: 105.3 cm; diameter: 2.1 cm) at an NLR of 25.3 ± 0.3 kg TN ha(-1)·d(-1). However, growth decreased to 94.4% at an NLR of over 25.3 ± 0.3 kg TN ha(-1)·d(-1) (>379.9 mg NH4(+)-N L(-1)) in autumn (17.4 ± 2.4°C). This was associated with the period of plant senescence and the effects of ammonium phytotoxicity (379.9-624.2 mg NH4(+)-N L(-1)) and continued to the end of the study with the complete loss of macrophyte species. Finally, 1.5% of the TN removed was incorporated into the sediments where NH4(+)-N is the main form of nitrogen, with an accumulative value of 2.6 g m(-2).

Free water molecules and hydrogen bonding form the basis of variation in homeopathic potencies as revealed by vibrational spectroscopy

Objective: Using Fourier Transform Infrared spectroscopy (FTIR) we have demonstrated that homeopathic potencies of Natrum mur, Cantharis, Nux vomica and Sulphur show differences with respect to the number of free water molecules and strength of hydrogen bonding. The purpose of the present study is to confirm this phenomenon in three potencies of two more drugs Calcarea carb and Silicea. Design: The potencies used for each of the two drugs were 30cH, 200cH and 1000cH. The control was 90% ethanol as also the potentized drugs. The control, as well as the potencies, were diluted with distilled water to reduce the level of ethanol to 0.03 molar fraction in each of them. FTIR spectra of all the potentized drugs, control and sterile distilled water (reference water) were taken in the wave number region of 4000-2800 cm-1. The full width at half maximum (fwhm) of OH band was measured for each spectrum. The width was divided into two in the middle. The difference spectrum (absorbance of drug solution - absorbance of reference water) for each potency and the control was obtained after normalization of the spectrum at 3410 cm-1. One difference spectrum so obtained for a potency was subtracted from another to find out if there is a difference between two different potencies. Results: The half width half maximum (hwhm) in both the high and low-frequency sides of the OH band is far less narrow in potencies than in the control as compared to that in water. The difference spectra for different potencies show different levels of fall in intensity at the wave number region of dip at 3630 cm-1. The level of dip at 3630 cm-1 and subsequent rise in intensity in the lower frequency region represent the quantity of free water molecules and strong alcoholic OH bond around 3250 cm-1, respectively. The results of subtraction between two different potencies are not zero but have marked positive or negative values. Conclusion (i) Potencies have stronger intermolecular interactions and a higher number of chemical environments than the control, as revealed by the data on hwhm. (ii) The three potencies of each of the two drugs show distinct variation in the number of free water molecules and strength of hydrogen bonding. (iii) There exists both inter-drug and inter-potency variation as revealed by the difference spectra and results of subtraction between two difference spectra.(AU)

Free water molecules and hydrogen bonding form the basis of variation in homeopathic potencies as revealed by vibrational spectroscopy

Using Fourier Transform Infrared spectroscopy (FTIR) we have demonstrated that homeopathic potencies of Natrum mur, Cantharis, Nux vomica and Sulphur show differences with respect to the number of free water molecules and strength of hydrogen bonding. The purpose of the present study is to confirm this phenomenon in three potencies of two more drugs Calcarea carb and Silicea. Design: The potencies used for each of the two drugs were 30cH, 200cH and 1000cH. The control was 90% ethanol as also the potentized drugs. The control, as well as the potencies, were diluted with distilled water to reduce the level of ethanol to 0.03 molar fraction in each of them. FTIR spectra of all the potentized drugs, control and sterile distilled water (reference water) were taken in the wave number region of 4000-2800 cm-1. The full width at half maximum (fwhm) of OH band was measured for each spectrum. The width was divided into two in the middle. The difference spectrum (absorbance of drug solution - absorbance of reference water) for each potency and the control was obtained after normalization of the spectrum at 3410 cm-1. One difference spectrum so obtained for a potency was subtracted from another to find out if there is a difference between two different potencies. Results: The half width half maximum (hwhm) in both the high and low-frequency sides of the OH band is far less narrow in potencies than in the control as compared to that in water. The difference spectra for different potencies show different levels of fall in intensity at the wave number region of dip at 3630 cm-1...

Association between maintenance fluid tonicity and hospital-acquired hyponatremia.

OBJECTIVE: To evaluate whether the administration of hypotonic fluids compared with isotonic fluids is associated with a greater risk for hyponatremia in hospitalized children. STUDY DESIGN: Informatics-enabled cohort study of all hospitalizations at Lucile Packard Children's Hospital between April 2009 and March 2011. Extraction and analysis of electronic medical record data identified normonatremic hospitalized children who received either hypotonic or isotonic intravenous maintenance fluids upon admission. The primary exposure was the administration of hypotonic maintenance fluids, and the primary outcome was the development of hyponatremia (serum sodium <135 mEq/L). RESULTS: A total of 1048 normonatremic children received either hypotonic (n = 674) or isotonic (n = 374) maintenance fluids upon admission. Hyponatremia developed in 260 (38.6%) children who received hypotonic fluids and 104 (27.8%) of those who received isotonic fluids (unadjusted OR 1.63; 95% CI 1.24-2.15, P < .001). After we controlled for intergroup differences and potential confounders, patients receiving hypotonic fluids remained more likely to develop hyponatremia (aOR 1.37, 95% CI 1.03-1.84). Multivariable analysis identified additional factors associated with the development of hyponatremia, including surgical admission (aOR 1.44, 95% CI 1.09-1.91), cardiac admitting diagnosis (aOR 2.08, 95% CI 1.34-3.20), and hematology/oncology admitting diagnosis (aOR 2.37, 95% CI 1.74-3.25). CONCLUSIONS: Hyponatremia was common regardless of maintenance fluid tonicity; however, the administration of hypotonic maintenance fluids compared with isotonic fluids was associated with a greater risk of developing hospital-acquired hyponatremia. Additional clinical characteristics modified the hyponatremic effect of hypotonic fluid, and it is possible that optimal maintenance fluid therapy now requires a more individualized approach.

Aspectos da função renal em portadores do vírus da imunodeficiência humana / Renal function aspects in carriers of the human immunodeficiency virus

Verificou-se a ocorrência de alterações em alguns parâmetros da função renal de indivíduos infectados pelo virus da imunodeficiência humana (HIV), assintomáticos. Foram estudados 47 indivíduos, realizando-se provas funcionais renais: depuração de creatinina endógena, depuração de água livre, depuração osmolar, reabsorção tubular proximal e distal de sódio, excreção fracional de sódio e potássio e pH urinário. Os resultados revelaram diferenças significantes (p < 0,05) no pH urinário, maior no grupo HIV (6,36 ± 0,41), do que nos controles (6,02 ± 0,41); na depuração de água livre, que indicou reabsorção de água maior no grupo HIV (1,00 ± 0,64ml/min), do que nos controles (0,53 ± 0,48ml/min) e na depuração osmolar, que foi 2,00 ± 0,83ml/min no grupo HIV e 1,57 ± 0,48ml/min nos controles. O restante dos indicadores de função renal estudados não se mostraram diferentes estatisticamente entre um e outro grupo. Concluiu-se que essas diferenças são significativas, apesar de os valores absolutos estarem dentro da normalidade, pois podem estar associadas a alterações evolutivas tardias da doença, tais como o aumento na frequência de infecções do trato urinário e a hiponatremia dilucional. Mais estudos são necessários para se confirmarem essas hipóteses.

The occurrence of alterations was verified in some parameters of the asymptomatic individuals' renal function infected by the virus of the human immunodeficiency (HIV). Forty seven individuals were studied, taking place renal functional tests, as: creatinine clearance, clearance of free water, clearance osmolar, reabsorption tubular proximal and distal of sodium and potassium and urinary pH. The results revealed significant differences (p < 0.05) in the urinary pH, larger in the group with HIV (6.36 +/- 0.41), that in the controls (6.02 +/- 0.41); in the clearance of free water, that indicated reabsorption of larger water in the group with HIV (1.00 +/- 0.64 ml/min) and in the clearance osmolar, that was 2.00 +/- 0.83 ml/min in the group with HIV and 1.57 +/- 0.48 ml/min. The remaining of the indicators of renal function was not shown statistically different between an and other group. It was ended that those differences are significant, in spite of the absolute values they be inside of the normality, because could be associated to late evolutionary alterations of the disease, such as the increase of the frequency of infections of the urinary treatment and the dilution hyponatremia. More studies are necessary for if they confirm those hypotheses.