Central Nervous System Function in Youth With Type 1 Diabetes 12 Years After Disease Onset

OBJECTIVE—In this study, we used neurocognitive assessment and neuroimaging to examine brain function in youth with type 1 diabetes studied prospectively from diagnosis

MAS NMR measurements of intact articular bovine cartilage

Articular cartilage (AC), an avascular connective tissue lining articulating surfaces of the long bones, comprises extracellular biopolymers. In functionally compromised states such as osteoarthritis, thinned or lost AC causes reduced mobility and increased health-care costs. Understanding of the characteristics responsible for the load bearing efficiency of AC and the factors leading to its degradation are incomplete. DTI shows the structural alignment of collagen in AC [1] and T2 relaxation measurements suggest that the average director of reorientational motion of water molecules depends on the degree of alignment of collagen in AC [2]. Information on the nature of the chemical interactions involved in functional AC is lacking. The need for AC structural integrity makes solid state NMR an ideal tool to study this tissue. We examined the contribution of water in different functional ‘compartments’ using 1H-MAS, 13C-MAS and 13C-CPMAS NMR of bovine patellar cartilage incubated in D2O. 1H-MAS spectra signal intensity was reduced due to H/D exchange without a measureable redistribution of relative signal intensity. Chemical shift anisotropy was estimated by lineshape analysis of multiple peaks in the 1H-MAS spinning sidebands. These asymmetrical sidebands suggested the presence of multiple water species in AC. Therefore, water was added in small aliquots to D2O saturated AC and the influence of H2O and D2O on organic components was studied with 13C-MAS-NMR and 13C-CPMAS-NMR. Signal intensity in 13C-MAS spectra showed no change in relative signal intensity throughout the spectrum. In 13C-CPMAS spectra, displacement of water by D2O resulted in a loss of signal in the aliphatic region due to a reduction in proton availability for cross-polarization. These results complement dehydration studies of cartilage using osmotic manipulation [3] and demonstrate components of cartilage that are in contact with mobile water

Effect of magnesium depletion and potassium and chlorothiazide on intracellular pH in the rat, studied by 31P NMR

1. Both dietary magnesium depletion and potassium depletion (confirmed by tissue analysis) were induced in rats which were then compared with rats treated with chlorothiazide (250 mg/kg diet) and rats on a control synthetic diet. 2. Brain and muscle intracellular pH was measured by using a surface coil and [31P]-NMR to measure the chemical shift of inorganic phosphate. pH was also measured in isolated perfused hearts from control and magnesium-deficient rats. Intracellular magnesium status was assessed by measuring the chemical shift of β-ATP in brain. 3. There was no evidence for magnesium deficiency in the chlorothiazide-treated rats on tissue analysis or on chemical shift of β-ATP in brain. Both magnesium and potassium deficiency, but not chlorothiazide treatment, were associated with an extracellular alkalosis. 4. Magnesium deficiency led to an intracellular alkalosis in brain, muscle and heart. Chlorothiazide treatment led to an alkalosis in brain. Potassium deficiency was associated with a normal intracellular pH in brain and muscle. 5. Magnesium depletion and chlorothiazide treatment produce intracellular alkalosis by unknown mechanism(s)

A study of the diffusion characteristics of normal, delipidized and relipidized articular cartilage using magnetic resonance imaging

This paper assesses the capacity to provide semipermeability of the synthetic layer of surface-active phospholipids created to replace the depleted surface amorphous layer of articular cartilage. The surfaces of articular cartilage specimens in normal, delipidized, and relipidized conditions following incubation in dipalmitoyl-phosphatidylcholine and palmitoyl-oleoyl-phosphatidylcholine components of the joint lipid mixture were characterized nanoscopically with the atomic force microscope and also imaged as deuterium oxide (D2O) diffused transiently through these surfaces in a magnetic resonance imaging enclosure. The MR images were then used to determine the apparent diffusion coefficients in a purpose-built MATLAB®-based algorithm. Our results revealed that all surfaces were permeable to D2O, but that there was a significant difference in the semipermeability of the surfaces under the different conditions, relative to the apparent diffusion coefficients. Based on the results and observations, it can be concluded that the synthetic lipid that is deposited to replace the depleted SAL of articular cartilage is capable of inducing some level of semipermeability

NMR relaxation behavior and quadrupole coupling constants of 39K and 23Na ions in glycerol. Comparisons with 39K tissue data

The quadrupole coupling constants (qcc) for39K and23Na ions in glycerol have been calculated from linewidths measured as a function of temperature (which in turn results in changes in solution viscosity). The qcc of39K in glycerol is found to be 1.7 MHz, and that of23Na is 1.6 MHz. The relaxation behavior of39K and23Na ions in glycerol shows magnetic field and temperature dependence consistent with the equations for transverse relaxation more commonly used to describe the reorientation of nuclei in a molecular framework with intramolecular field gradients. It is shown, however, that τc is not simply proportional to the ratio of viscosity/temperature (ηT). The 39K qcc in glycerol and the value of 1.3 MHz estimated for this nucleus in aqueous solution are much greater than values of 0.075 to 0.12 MHz calculated from T2 measurements of39K in freshly excised rat tissues. This indicates that, in biological samples, processes such as exchange of potassium between intracellular compartments or diffusion of ions through locally ordered regions play a significant role in determining the effective quadrupole coupling constant and correlation time governing39K relaxation. T1 and T2 measurements of rat muscle at two magnetic fields also indicate that a more complex correlation function may be required to describe the relaxation of39K in tissue. Similar results and conclusions are found for23Na

Seizure-associated abnormalities in epilepsy: Evidence from MR imaging

Acute seizure-associated changes have been described in the animal and human literature. Controversy exists over whether seizures cause permanent damage to the brain, and whether a (prolonged) seizure can induce changes that lead to an epileptic lesion, resulting in habitual seizures and epilepsy. Current magnetic resonance imaging (MRI) offers a variety of imaging tools and is capable of detecting acute seizure-associated changes. In contrast to the histologic examination, serial MRI studies are possible and allow longitudinal observation of the fate of these changes. This report reviews the literature on acute seizure-associated effects emphasizing the MRI evidence

Magnetic resonance spectroscopy in epilepsy

Key points \ud • The clinical aims of MR spectroscopy (MRS) in \ud seizure disorders are to help identify, localize \ud and characterize epileptogeic foci. \ud • Lateralizing MRS abnormalities in temporal lobe \ud epilepsy (TLE) may be used clinically in combi- \ud nation with structural and T2measurements. \ud • Characteristic metabolite abnormalities are \ud decreased N-acetylaspartate (NAA) with \ud increased choline (Cho) and myoinositol (mI) \ud (short-echo time). \ud • Contralateral metabolite abnormalities are \ud frequently seen in TLE, but are of uncertain \ud significance. \ud • In extra-temporal epilepsy, metabolite abnor- \ud malities may be seen where MR imaging (MRI) \ud is normal; but may not be sufficiently local- \ud ized to be useful clinically. \ud • MRS may help to characterize epileptogenic \ud lesions visible on MRI (aggressive vs. indolent \ud neoplastic, dysplasia). \ud • Spectral editing techniques are required to \ud evaluate specific epilepsy-relevant metabolites \ud (e.g. -aminobutyric acid (GABA)) which may \ud be useful in drug development and evaluation. \ud • MRS with phosphorus (31P) and other nucleii \ud probe metabolism of epilepsy, but are less \ud useful clinically

Investigation of cellular level of water in plant-based food material

Water in plant tissue is generally distributed in three different spaces namely, intercellular water, intracellular water, and cell wall water. For hygroscopic material, these three water states should be considered for understanding heat and mass transfer during drying. However, to the authors’ best knowledge, the proportion of these three types of water in plant-based food tissue has not yet been investigated. The present study was performed to investigate the proportion of intercellular water, intracellular water, and cell wall water inside plant-based food material. In this study, experiments were performed for two different plant-based food tissues namely, granny smith apple and potato. H1-NMR relaxation measurement offers a unique method for investigating the physical state of tissue water in compartments by using T2 relaxometry. The different water environments were calculated by using multicomponent fits of the T2 relaxation curves. The experimental results confirmed that plant-based food materials contain about 80 to 92 % LBW, 6 to 16 % free water and only about 1 to 6 % SBW. An attempt was made to establish the relationship between physical properties of fruits and vegetables and the proportion of different water environments. Interestingly, it was found that SBW strongly depends on the proportion of solid in the sample tissue, whereas FW depends on the porosity of the material

Aromatic l-amino acid decarboxylase : histochemical localization in rat kidney and lack of effect of dietary potassium or sodium loading on enzyme distribution

Utilizing a mono-specific antiserum produced in rabbits to hog kidney aromatic L-amino acid decarboxylase (AADC), the enzyme was localized in rat kidney by immunoperoxidase staining. AADC was located predominantly in the proximal convoluted tubules; there was also weak staining in the distal convoluted tubules and collecting ducts. An increase in dietary potassium or sodium intake produced no change in density or distribution of AADC staining in kidney. An assay of AADC enzyme activity showed no difference in cortex or medulla with chronic potassium loading. A change in distribution or activity of renal AADC does not explain the postulated dopaminergic modulation of renal function that occurs with potassium or sodium loading