What can 7T sodium MRI tell us about cellular energy depletion and neurotransmission in Alzheimer's disease?

The pathophysiological processes underlying the development and progression of Alzheimer's disease (AD) on the neuronal level are still unclear. Previous research has hinted at metabolic energy deficits and altered sodium homeostasis with impaired neuronal function as a potential metabolic marker relevant for neurotransmission in AD. Using sodium (23 Na) magnetic resonance (MR) imaging on an ultra-high-field 7 Tesla MR scanner, we found increased cerebral tissue sodium concentration (TSC) in 17 biomarker-defined AD patients compared to 22 age-matched control subjects in vivo. TSC was highly discriminative between controls and early AD stages and was predictive for cognitive state, and associated with regional tau load assessed with flortaucipir-positron emission tomography as a possible mediator of TSC-associated neurodegeneration. TSC could therefore serve as a non-invasive, stage-dependent, metabolic imaging marker. Setting a focus on cellular metabolism and potentially disturbed interneuronal communication due to energy-dependent altered cell homeostasis could hamper progressive cognitive decline by targeting these processes in future interventions.

Unravelling the Origin of the Yellow-Orange Luminescence in Natural and Synthetic Scapolites.

After decades of speculation without material proof, the yellow-orange luminescence of scapolite is definitely assigned to (S2)- activators trapped in [Na4] square cages. Synthetic sulfur-doped scapolites confirm the implication of sulfur species in luminescence. Formally, the emission and excitation spectra of various polysulfide species were calculated. The excellent match between theory and experiments for (S2)- dimers provides definitive proof that it is the cause of the yellow-orange luminescence in scapolite.

Temporal Fluctuations in Indoor Background Gamma Radiation Using NaI(Tl).

An enhanced understanding of background gamma radiation is necessary for accurate radionuclide activity quantification. Background spectra are routinely subtracted from spectra of samples prepared in known geometries, with data collection time chosen to optimize statistics for counting uncertainties. The work presents measured background spectra collected inside and outside shields of varying geometry and composition, showing the effects of these on background. Gamma background measurements with and without blank samples are included along with spectra from different sizes and shapes of NaI(Tl) detectors. If the environment is being monitored for quick and confident detection of recently appearing radiation sources, a thorough knowledge of the background radiation and its temporal variation is essential. To study the requirements of such background measurements, sequential background gamma radiation collections were obtained on an hourly basis for a total of 316 h from an unshielded 5.5 × 11 × 40 cm NaI(Tl) detector located inside a laboratory setting where small sources are routinely stored and used. Finally, a strategy for optimizing data collection times and analyzing background gamma radiation spectra for long-term radionuclide monitoring is presented.

Presence of divalent cation is not mandatory for the formation of intramolecular purine-motif triplex containing human c-jun protooncogene target.

Modulation of endogenous gene function, through sequence-specific recognition of double helical DNA via oligonucleotide-directed triplex formation, is a promising approach. Compared to the formation of pyrimidine motif triplexes, which require relatively low pH, purine motif appears to be the most gifted for their stability under physiological conditions. Our previous work has demonstrated formation of magnesium-ion dependent highly stable intermolecular triplexes using a purine third strand of varied lengths, at the purine•pyrimidine (Pu•Py) targets of SIV/HIV-2 (vpx) genes (Svinarchuk, F., Monnot, M., Merle, A., Malvy, C., and Fermandjian, S. (1995) Nucleic Acids Res. 23, 3831-3836). Herein, we show that a designed intramolecular version of the 11-bp core sequence of the said targets, which also constitutes an integral, short, and symmetrical segment (G(2)AG(5)AG(2))•(C(2)TC(5)TC(2)) of human c-jun protooncogene forms a stable triplex, even in the absence of magnesium. The sequence d-C(2)TC(5)TC(2)T(5)G(2)AG(5)AG(2)T(5)G(2)AG(5)AG(2) (I-Pu) folds back twice onto itself to form an intramolecular triple helix via a double hairpin formation. The design ensures that the orientation of the intact third strand is antiparallel with respect to the oligopurine strand of the duplex. The triple helix formation has been revealed by non-denaturating gel assays, UV-thermal denaturation, and circular dichroism (CD) spectroscopy. The monophasic melting curve, recorded in the presence of sodium, represented the dissociation of intramolecular triplex to single strand in one step; however, the addition of magnesium bestowed thermal stability to the triplex. Formation of intramolecular triple helix at neutral pH in sodium, with or without magnesium cations, was also confirmed by gel electrophoresis. The triplex, mediated by sodium alone, destabilizes in the presence of 5'-C(2)TC(5)TC(2)-3', an oligonucleotide complementary to the 3'-oligopurine segments of I-Pu, whereas in the presence of magnesium the triplex remained impervious. CD spectra showed the signatures of triplex structure with A-like DNA conformation. We suggest that the possible formation of pH and magnesium-independent purine-motif triplexes at genomic Pu•Py sequences may be pertinent to gene regulation.

Ultrasonic-assisted transesterification of Jatropha curcus oil using solid catalyst, Na/SiO2.

The production of biodiesel from non-edible vegetable oil using ultrasonication, calls for an efficient solid catalyst to make the process fully ecologically and economically friendly. The methodology allows for the reaction to be run under atmospheric conditions. Solid catalyst and ultrasonication reduced the reaction time comparing to the conventional batch processes and we found 98.53% biodiesel yield. The optimal conditions for biodiesel production is the molar ratio oil to methanol 1:9, Catalyst conc. 3 wt.% of oil and 15 min reaction time.

Solvent-free sonochemical preparation of alpha-aminophosphonates catalyzed by 1-hexanesulphonic acid sodium salt.

1-Hexanesulphonic acid sodium salt was found to be an efficient catalyst for the green synthesis of alpha-aminophosphonates by the coupling of aldehydes/ketone, an amine and triethyl phosphite under ultrasound irradiation at ambient temperature for appropriate time to furnish the desired product in good to excellent yield under solvent-free condition. This catalyst provides clean conversion; greater selectivity and easy workup make this protocol practical and economically attractive.

Photolysis of the herbicide bispyribac sodium in aqueous medium under the influence of UV and sunlight in presence or absence of sensitizers.

The photolysis of a rice herbicide Bispyribac sodium (Sodium 2, 6-bis [(4, 6-dimethoxypyrimidin-2-yl) oxy] benzoate) has been studied in different aqueous medium (distilled water, pond water and Irrigation water) under the influence of UV (lambda max > or = 250 nm) and sunlight in presence or absence of sensitizers (TiO(2) and KNO(3)). The study was conducted under laboratory simulated condition which made it possible to evaluate the contribution of different factors viz. source of irradiation, solvent and sensitizers towards the photolysis of bispyribac sodium. The photodegradation proceeds via first order reaction Kinetics in all the cases. Five photo metabolites (M(1)-M(5)) were isolated in pure form by column chromatographic method from the irradiation system under UV influenced and TiO(2) as sensitizer. From the different spectral data (IR, NMR, UV-VIS, Mass) the structure of these five metabolites were assigned as M(1) (Phenol), M(2) [2, 6-Dihydroxy benzoic acid], M(3) [2, 6-bis [(4, 6 dimethoxypyrimidin-2yl) oxy] benzoic acid], M(4) [2-(3-Hydroxy-phenoxy)-pyrimidine-4, 6-diol] and M(5) as [2,4-Dihydroxy-3, 5-dimethoxy-6-(4-methoxy pyrimidine-2-yloxy)-benzoic acid]. Moreover, another six photometabolites (M(6)-M(11)) were identified from the different irradiation system on the basis of Micromass analysis. On the basis of MS/MS data analysis, the structure of these six photometabolites were assigned as M(6) [2-(4, 6-Dimethoxy-pyrimidin-2-yloxy)-6-hydroxy-benzoic acid], M(7) [2-Hydroxy-6-(4-hydroxy-6-methoxy-pyrimidin-2-yloxy)-benzoic acid], M(8) [4, 6-Dimethoxy-pyrimidin-2-ol], M(9) [6-Methoxy-pyrimidine-2, 4-diol], M(10) [2-Hydroxy-6-(pyrimidin-2-yloxy)-benzoic acid] and M(11) [2, 4, 6-Trimethoxy-pyrimidine]. The plausible Photodegradation pathways of bispyribac sodium in the present investigation were portrayed which proceeds via hydrolysis, hydrolytic cleavage, O-dealkylation, decarboxylation, dehydroxylation, O-alkylation and hydroxylation.

Effects of radiation and alpha-tocopherol on saliva flow rate, amylase activity, total protein and electrolyte levels in oral cavity cancer.

OBJECTIVE: The objective of the present study was to evaluate early and late effects of radiation and a-tocopherol on the secretion rate of saliva and on selected saliva salivary parameters in oral cavity cancer patients. PATIENTS & METHODS: Eighty-nine histologically confirmed oral cavity cancer patients (OCC) were enrolled in the study. Resting whole saliva was collected before, during and at the end of the radiation therapy (RT) and simultaneous supplementation with alpha - tocopherol to the radiation treated patients (RT + AT). RESULTS: Salivary flow rate, pH, amylase activity, total protein, sodium and potassium were analyzed. Increased pH, potassium and decreased flow rate, amylase activity, protein content and sodium were observed in 6 weeks of radiation treated patients when compared to OCC patients. A significant improvement of those parameters was observed on alpha - tocopherol supplementation in RT + AT patients. CONCLUSION: Supplementation with alpha - tocopherol improves the salivary flow rate thereby, maintains salivary parameters.

Thermoluminescence emission spectra for the LiF:Mg,Cu,Na,Si thermoluminescent materials with various concentrations of the dopants (3-D measurement).

The thermoluminescence (TL) emission spectra from LiF TL materials, called KLT-300 (LiF:Mg,Cu,Na,Si) with various dopant concentrations are measured and analysed. These KLT-300 materials were developed by the Korea Atomic Energy Research Institute (KAERI) to achieve an enhancement of the thermal stability in TL readings. Six types of samples are prepared with different dopant concentrations in the following ranges; Mg (0-0.20 mol%), Cu (0-0.05 mol%), Na and Si (0-0.9 mol%). The spectra measurements are carried out for the six types of samples using a TL emission spectra measurement device. The spectra measurement device consists of a monochromator, photomultiplier tube and temperature control unit to thermally stimulate the samples. The measured data shows the light emission during heating of the sample as a function of temperature and wavelength (three-dimensional TL spectra). The spectra were analysed using a method of deconvolution based on gaussian curve. The wavelength of a main peak of the emission spectra changes depending on the existence of the Cu dopant, while intensity of the spectra rapidly changes with the Cu dopant concentrations. The 385 nm emission is mainly observed in all the spectra from the samples with the Cu dopant, but in those from the samples without the Cu dopant a very weak 401 nm emission is mainly observed. However, any change in the wavelength at a main peak of the TL emission spectra from the sample materials with Na and Si dopants is not observed but that in the intensity at a peak of the spectra is observed.

Photoemission from sodium on ice: a mechanism for positive and negative charge coexistence in the mesosphere.

Photoemission from sodium deposited on ice films is described. Deposition of 0.02 ML of sodium is found to dramatically reduce the threshold for photoemission from the ice film to (2.3+/-0.2) eV. Thus, the cross-section for photoemission reaches >10(-18) cm2 in the visible region of the spectrum. It is proposed that the initial state is a solvated electron on the ice surface, which is supported by optical transmission spectroscopy. The potential significance of these results in understanding unexplained charging phenomena in the mesosphere is discussed.

The effect of oscillating low intensity magnetic field on the Na+, K+, Ca++, and Mg++ concentrations in the maternal and fetal circulation of the dually perfused human placental cotyledon.

Dual-sided perfusions of the human placental cotyledon in vitro were used to study effects of low intensity magnetic fields (MFs) of 2 mT, 50 Hz (E1, 10 perfusions) and 5 mT, 50 Hz (E2, 10 perfusions). In the control group C (10 experiments) no field was used. Perfusions lasted 180 min each. Increased release of calcium ions from the placental cotyledon was found in the fetal circulation during perfusion when the 2 mT, 50 Hz MF was used. No changes in the release of sodium and magnesium ions were observed compared to the control group. The 5 mT, 50 Hz oscillating MF intensified the release of sodium ions from the perfused cotyledon both to the fetal and maternal circulation up to the 150th min of the experiment. Increased release of magnesium ions was observed only to the fetal circulation between 120 and 180 min and of calcium ions to the fetal circulation between 60 and 180 min. No significant differences in K concentrations were found between the control and MF exposed cotyledons under conditions of these experiments.

59Co, 23Na NMR and electric field gradient calculations in the layered cobalt oxides NaCoO2 and HCoO2.

59Co and 23Na NMR has been applied to the layered cobalt oxides NaCoO(2) and HCoO(2) at three different magnetic field strengths (4.7, 7.1 and 11.7T). The 59Co and 23Na quadrupole and anisotropic shift tensors have been determined by iterative fitting of the NMR line shapes at the three magnetic field strengths. Due to the large 59Co quadrupole interaction in NaCoO(2), a frequency-swept irradiation procedure was used to alleviate the limited bandwidth of the excitation. While the 59Co and 23Na shift and quadrupole coupling tensors in NaCoO(2) are found to be coincident and axially symmetric in agreement with the crystal symmetry requirements, the fits of the 59Co NMR spectra clearly show the presence of structural disorder in HCoO(2). The 23Na chemical shift anisotropy can be reproduced by shift tensor calculations using a point dipole model and considering that the magnetic susceptibility in NaCoO(2) is due to Van Vleck paramagnetism for Co(3+). Electric field gradient calculations using either the empirical point charge model or the ab initio full potential-linearized augmented plane wave method are compared with the experimental NMR data.

Evaluation of systematic errors in thyroid monitoring.

In this manuscript the thyroid is described by a new model. Efficiencies of a NaI(Tl) detector, for 364 keV photons, are calculated using Monte Carlo simulation. Contributions from thyroid size, detector placement and tissue overlay thickness, to the efficiency uncertainty, are evaluated considering the thyroid of a 12 year old subject as a limit for the adult thyroid. For a shielded 3" x 3" NaI(Tl) detector, placed at 20 cm from the neck, a contribution of 18% to the efficiency uncertainty was found.

[The effect of high-dose ultraviolet irradiation on sodium, calcium and aldosterone in the blood of calves]. / Pôsobenie nadmerného ultrafialového ziarenia na sodík, vápnik a aldosteron v plazme teliat.

Five Holstein-Friesian calves, from one sire, with prevalent black hair coat pigmentation were used in the experiment. The mean age was 33 days and the mean live weight 51 kg. The animals were exposed free running without interruption for 12 hours to an artificial ultraviolet light in the range of 280-320 nm. The mean doses of radiation was 179.10(-10) J/h/m. One-spot high-pressure mercury discharge lamps Tesla RVK 400 W were used as a radiation source. The dose rate was estimated from measurements by a spectral photometer with filter UG 2 for absorbtion of visible light located at the height of the back of standing calf. Blood samples were collected immediately before the beginning of treatment and after 5, 12, 24, 48 and 72 hours. The blood plasma aldosterone was measured by radioimmunoassays, the levels of sodium, potassium and calcium in blood plasma by flame spectrophotometry. Double classification variance analysis and evaluation according to the Snedecor F-test, the contrast effect test according to Duncan and regression analysis were used for statistical evaluation. Compared to the first sampling, sodium increased significantly after 5 and 12 hours of exposure (Tab. I) to 138.1 and 138.3 mmol/l, respectively. In the subsequent samplings this trend continued up to 72 hours from the beginning of irradiation (140.5 mmol/l). The potassium level did not change statistically significantly. Owing to an excessive irradiation, the calcium concentration increased significantly. The greatest increase occurred after 12 hours of irradiation (from 2.29 mmol/l to 2.61 mmol/l) and after 36 hours from the end of irradiation (2.70 mmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of ultraviolet irradiation on calcium, sodium and potassium levels in albino rats]. / Vliianie ul'trafioletovogo oblucheniia na soderzhanie kal'tsiia, natriia i kaliia v organizme belykh krys.

Data presented by the authors testifies to the fact that neither 2 weeks, nor one month after the 10-day course of ultraviolet irradiation (UVR) with an intensity from 1/4 up to 2 biodoses daily changes in calcium, sodium and potassium content in blood serum of laboratory animals (white rats) were detected. At the same time, 2 weeks following the cessation of UVR course a tendency towards calcium accumulation in the whole organism of laboratory animals was observed, which was most noticeable+ after daily 10-day exposure to UVR with an intensity from 1/2 up to 1 biodose. The tendency was still present one month following the termination of UVR course. The total sodium and potassium store in the whole organism of laboratory animals did not practically change either immediately, or 2 weeks, or 1 month after the termination of 10-day UVR course with the intensity from 1/4 to 2 biodoses daily.

[The action of ionizing radiation on neuronal function in the edible snail. Phospholipase A2 and the Na+ and K+ transport systems]. / Deistvie ioniziruiushchei radiatsii na funktsional'noe sostoianie neironov vinogradnoi ulitki. Fosfolipaza A2 i sistemy transporta Na+ i K+.

A study was made of the influence of A2 phospholipase on 22Na release from cells of nerve ganglia of edible snail. The treatment of nerve ganglia with A2 phospholipase inhibits Na, K-pump of neuronal membranes and does not exert a substantial effects on Na/Ca metabolism. There is a similarity between the effects of ionizing radiation and A2 phospholipase on the release of 22Na from cells.

[Ionic permeability of sarcoplasmic reticulum membranes damaged by x-rays]. / Ionnaia pronitsaemost' membran sarkoplazmaticheskogo retikuluma pri porazhenii rentgenovskim izlucheniem.

As early as 1 and 24 h following single local X-irradiation (0.21 C/kg) of rabbit hindlimbs an increase was noted in the permeability of skeletal muscle sarcoplasmic reticulum membranes for Ca2+, K+ and Na+. The effect was maximum 1 h after irradiation and more pronounced for K+ and Na+ than Ca2+.

[Modifying effect of ionizing radiation on the transmembrane transport of sodium ions in Ehrlich carcinoma tumor cells]. / Modifitsiruiushchii éffekt ioniziruiushchei radiatsii na transmembrannyi perenos ionov natriia v opukholevykh kletkakh kartsinomy Erlikha.

The effect of a local X-irradiation on the transmembrane transfer of Na ions and activity of Na-K ATPase in Ehrlich ascites tumor cells has been investigated. Irradiation with doses of 0.05 and 0.15 C/kg are shown to change natrium ion transport. This effect is absent at a dose of 0.08 C/kg. A change in the rate of active transport correlates to some extent with the disturbance in Na-K ATPase occurring at the same radiation doses.

A search for nonthermal effects of 434 MHz microwave radiation on whole human blood.

Whole human blood was subjected to a microwave environment at 434 MHz for 6 hr with external electric fields corresponding to free space power densities up to 598 mW cm-2 and the levels of hemoglobin, sodium, and potassium in the plasma were monitored. Under geometrical conditions in which the field strength within the samples was unknown, measurements indicated increased red cell membrane fragility following irradiation. It was not possible to exclude localized heating as an explanation of this effect. However, with a known and reasonably uniform electric field distribution within spherical specimens, increased membrane fragility was not observed. We are therefore unable to confirm previously reported results which indicate a nonthermal deleterious effect of microwave radiation on erythrocytes.