Magnetic Resonance Imaging (MRI) Analysis of Tissue Sodium Concentration in Chronic Kidney Disease

Human body sodium is regulated by the kidneys and extrarenal mechanisms. Stored skin and muscle tissue sodium accumulation is associated with kidney function decline, hypertension, and a pro-inflammatory and cardiovascular disease profile. In this chapter, we describe the use of sodium-hydrogen magnetic resonance imaging (²³Na/¹H MRI) to dynamically quantify tissue sodium concentration in the lower limb of humans. Real-time quantification of tissue sodium is calibrated against known sodium chloride aqueous concentrations. This method may be useful for investigating in vivo (patho-)physiological conditions associated with tissue sodium deposition and metabolism (including in relation to water regulation) to enlighten our understanding of sodium physiology.

Optimal spatial filter selection for illumination-invariant color texture discrimination

Color textures contain a large amount of spectral and spatial structure that can be exploited for recognition. Recent work has demonstrated that spatial filters offer a convenient means of extracting illumination-invariant spatial information from a color image. In this paper, we address the problem of deriving optimal filters for illumination-invariant color texture discrimination. Color textures are represented by a set of illumination-invariant features that characterize the color distribution of a filtered image region. Similar features have been used in previous studies. Given a pair of color textures, we derive a spatial filter that maximizes the distance between these textures in feature space. We provide a method for using the pairwise result to obtain a filter that maximizes discriminability among multiple classes. A set of experiments on a database of deterministic and random color textures obtained under different illumination conditions demonstrates the improved discriminatory power achieved by using an optimized filter.

Targeted disruption of the type 1 selenodeiodinase gene (Dio1) results in marked changes in thyroid hormone economy in mice

The type 1 deiodinase (D1) is thought to be an important source of T3 in the euthyroid state. To explore the role of the D1 in thyroid hormone economy, a D1-deficient mouse (D1KO) was made by targeted disruption of the Dio1 gene. The general health and reproductive capacity of the D1KO mouse were seemingly unimpaired. In serum, levels of T4 and rT3 were elevated, whereas those of TSH and T3 were unchanged, as were several indices of peripheral thyroid status. It thus appears that the D1 is not essential for the maintenance of a normal serum T3 level in euthyroid mice. However, D1 deficiency resulted in marked changes in the metabolism and excretion of iodothyronines. Fecal excretion of endogenous iodothyronines was greatly increased. Furthermore, when compared with both wild-type and D2-deficient mice, fecal excretion of [125I]iodothyronines was greatly increased in D1KO mice during the 48 h after injection of [125I]T4 or [125I]T3, whereas urinary excretion of [125I]iodide was markedly diminished. From these data it was estimated that a majority of the iodide generated by the D1 was derived from substrates other than T4. Treatment with T3 resulted in a significantly higher serum T3 level and a greater degree of hyperthyroidism in D1KO mice than in wild-type mice. We conclude that, although the D1 is of questionable importance to the wellbeing of the euthyroid mouse, it may play a major role in limiting the detrimental effects of conditions that alter normal thyroid function, including hyperthyroidism and iodine deficiency.

Quantitative PCR identifies a minimal deleted region of 120 kb extending from the Philadelphia chromosome ABL translocation breakpoint in chronic myeloid leukemia with poor outcome

Fluorescence in situ hybridization (FISH) analysis has shown previously that 10-15% of chronic myeloid leukemias (CML) have hemizygous deletions of variable sizes affecting regions that flank the ABL and BCR translocation breakpoints on the derivative chromosome 9, and these patients have a poor outcome. FISH studies using large commercial genomic probes have previously suggested that haploinsufficiency of sequences flanking either ABL or BCR modify the disease process of CML and lead to an unfavorable prognosis. In this present study, real-time quantitative PCR (Q-PCR) analysis was used to identify and map much smaller hemizygous microdeletions in a subset of CML patients that were not deleted using large genomic FISH probes. Microdeletions were identified by Q-PCR in 25 of 71 patients selected based on less favorable outcome (chronic phase duration of less than 96 months and a survival time of less than 84 months). In contrast, no microdeletion was detected in any of 18 CML samples selected from a group with a more favorable outcome. Detailed mapping of the 25 Q-PCR microdeletions showed that the minimal deleted region extended approximately 120 kb from the 5' end of the ABL gene in the centromeric direction on the derivative chromosome 9, and the region 3' to BCR on chromosome 22 was excluded. Of the four ESTs and/or genes that map to the 120 kb region, the putative tumor suppressor PRDM12 is the strongest candidate gene. The potential role for each sequence in modifying the clinical behavior of CML is presented.

Tachykinin-induced contraction of the guinea-pig isolated oesophageal mucosa is mediated by NK(2) receptors

1. The tachykinin receptor present in the guinea-pig oesophageal mucosa that mediates contractile responses of the muscularis mucosae has been characterized, using functional in vitro experiments. 2. The NK(1) receptor-selective agonist, [Sar(9)(O(2))Met(11)]SP and the NK(3) receptor-selective agonists, [MePhe(7)]-NKB and senktide, produced no response at submicromolar concentrations. The NK(2) receptor-selective agonists, [Nle(10)]-NKA(4 - 10), and GR 64,349 produced concentration-dependent contractile effects with pD(2) values of 8.20+/-0.16 and 8.30+/-0.15, respectively. 3. The concentration-response curve to the non-selective agonist, NKA (pD(2)=8.13+/-0.04) was shifted significantly rightwards only by the NK(2) receptor-selective antagonist, GR 159,897 and was unaffected by the NK(1) receptor-selective antagonist, SR 140,333 and the NK(3) receptor-selective antagonist, SB 222,200. 4. The NK(2) receptor-selective antagonist, GR 159,897, exhibited an apparent competitive antagonism against the NK(2) receptor-selective agonist, GR 64,349 (apparent pK(B) value=9.29+/-0.16) and against the non-selective agonist, NKA (apparent pK(B) value=8.71+/-0.19). 5. The NK(2) receptor-selective antagonist, SR 48,968 exhibited a non-competitive antagonism against the NK(2) receptor-selective agonist, [Nle(10)]-NKA(4 - 10). The pK(B) value was 10.84+/-0.19.6. It is concluded that the guinea-pig isolated oesophageal mucosa is a useful preparation for studying the effects of NK(2) receptor-selective agonists and antagonists as the contractile responses to various tachykinins are mediated solely by NK(2) receptors.