Multiple-mouse magnetic resonance imaging with cryogenic radiofrequency probes for evaluation of brain development.

Multiple-mouse magnetic resonance imaging (MRI) increases scan throughput by imaging several mice simultaneously in the same magnet bore, enabling multiple images to be obtained in the same time as a single scan. This increase in throughput enables larger studies than otherwise feasible and is particularly advantageous in longitudinal study designs where frequent imaging time points result in high demand for MRI resources. Cryogenically-cooled radiofrequency probes (CryoProbes) have been demonstrated to have significant signal-to-noise ratio benefits over comparable room temperature coils for in vivo mouse imaging. In this work, we demonstrate implementation of a multiple-mouse MRI system using CryoProbes, achieved by mounting four such coils in a 30-cm, 7-Tesla magnet bore. The approach is demonstrated for longitudinal quantification of brain structure from infancy to early adulthood in a mouse model of Sanfilippo syndrome (mucopolysaccharidosis type III), generated by knockout of the Hgsnat gene. We find that Hgsnat-/- mice have regionally increased growth rates compared to Hgsnat+/+ mice in a number of brain regions, notably including the ventricles, amygdala and superior colliculus. A strong sex dependence was also noted, with the lateral ventricle volume growing at an accelerated rate in males, but several structures in the brain parenchyma growing faster in females. This approach is broadly applicable to other mouse models of human disease and the increased throughput may be particularly beneficial in studying mouse models of neurodevelopmental disorders.

Inverse relationship of food and alcohol intake to sleep measures in obesity.

BACKGROUND: Short sleep and weight gain are inversely related. Sleep deprivation acutely increases food intake but little is known about eating behavior in chronically sleep-deprived, obese individuals. OBJECTIVE: To characterize the relationship between sleep, food intake and alcohol consumption under free-living conditions in obese, chronically sleep-deprived individuals. DESIGN: Cross-sectional study of a cohort of obese men and premenopausal women. SUBJECTS: A total of 118 obese subjects (age: 40.3±6.7 years; 91 females/27 males; body mass index 38.7±6.4 kg m(-2)). MEASUREMENTS: Energy, macronutrient, alcohol and caffeine intake assessed by 3-day food records. Sleep duration estimated by actigraphy. Respiratory disturbance index assessed by a portable device. RESULTS: SUBJECTS slept 360.7±50.2 min per night and had a total energy intake of 2279.1±689 kcal per day. Sleep duration and energy intake were inversely related (r=-0.230, P=0.015). By extrapolation, each 30-min deficit per day in sleep duration would translate to an ∼83 kcal per day increase in energy intake. In addition, sleep apnea was associated with a shift from carbohydrate to fat intake. Alcohol intake in subjects consuming >3.5 g of alcohol per day (N=41) was inversely related to sleep duration (r=-0.472, P=0.002). CONCLUSIONS: Shorter sleep duration and obstructive sleep apnea are associated with higher energy, fat and alcohol intakes in obese individuals. The importance of this study relies on the population studied, obese subjects with chronic sleep deprivation. These novel findings apply to the large segment of the US population who are obese and sleep-deprived.

Inclusive K(S);(0)K(S);(0) resonance production in ep collisions at HERA.

Inclusive K_{S};{0}K_{S};{0} production in ep collisions at the DESY ep collider HERA was studied with the ZEUS detector using an integrated luminosity of 0.5 fb;{-1}. Enhancements in the mass spectrum were observed and are attributed to the production of f_{2}(1270)/a_{2};{0}(1320), f_{2};{'}(1525) and f_{0}(1710). Masses and widths were obtained using a fit which takes into account theoretical predictions based on SU(3) symmetry arguments, and are consistent with the Particle Data Group values. The f_{0}(1710) state, which has a mass consistent with a glueball candidate, was observed with a statistical significance of 5 standard deviations. However, if this state is the same as that seen in gammagamma-->K_{S};{0}K_{S};{0}, it is unlikely to be a pure glueball state.

Examining the effect of residential change on intimate partner violence risk.

OBJECTIVES: To examine the relationship between residential change and a woman's subsequent risk of intimate partner violence (IPV), whether by a past or a new offender, a relationship that has not been prospectively examined to date. DESIGN: A dynamic cohort of women who recently changed residence (movers) was compared with those who did not (non-movers) for 12-month risk of IPV by a past offender and of IPV by a new offender. PARTICIPANTS AND METHODS: Secondary analysis of a linked, longitudinal National Crime Victimization Survey dataset including 10 754 recent movers and 10 236 non-movers among women aged 18-44 years. RESULTS: The risk of IPV by either a past or a new offender was almost double for women who had recently moved compared with those who had not moved. This increased risk proved to be robust, as it persisted when the data were weighted and unweighted, and when the main effect was adjusted by measured covariates. CONCLUSIONS: The apparent increase in IPV risk after residential change may be a marker of a pre-existing problem or a precursor of subsequent problems. Unlike past research that has considered residential change after abuse or as a simultaneous exposure, this study focused solely on empirically measuring the risk of IPV after a recent move. This decision has important public health ramifications: determination of IPV exposure is not always possible, whereas soliciting a woman's history of residence may be more feasible. If transience puts a woman at greater risk for victimisation by an intimate partner, increased awareness may have a vital role in protecting women who move.

A dynamic two-dimensional phantom for ultrasound hyperthermia controller testing.

A new thin layer phantom for testing hyperthermia controllers has been constructed and evaluated using an ultrasound hyperthermia system. The phantom's thermal behaviour agrees with the characteristics of the Pennes' bio-heat transfer equation (BHTE). In particular, the experimental and theoretical results agree in the following ways. First, with respect to the power deposition: for a given power magnitude and scan radius, the shape of the temperature distribution across the phantom corresponds to the shape predicted by the BHTE and the experimental and theoretical temperature values agree closely; when the power magnitude is varied at a fixed scan radius, the average temperature of the phantom varies linearly with the applied power, and as the scan radius is varied at a fixed power magnitude, the average temperature increases with decreasing scan radius size. Secondly, with respect to perfusion: increasing or decreasing the flow rate over the phantom simulates an increase or decrease in the BHTE perfusion term, and the estimated perfusion values are dependent on flow rate only, and are not functions of power or geometry. The combination of these experimental and theoretical results validate the phantom's potential for testing feedback control systems, particularly for future use in the development and verification of model-based controllers. The use of this phantom should improve and accelerate the testing and evaluation of feedback control systems, and reduce the need for animal and human testing.

Performance of compensation seeking and non-compensation seeking samples on the Victoria symptom validity test: cross-validation and extension of a standardization study.

Previous research suggests that the Victoria Symptom Validity Test (VSVT) is effective in confirming or disconfirming the validity of a patient's reported cognitive impairments. We sought to cross-validate the findings of the VSVT standardization study, and to determine cut-off scores that are most efficient in discriminating our samples of compensation-seeking patients, primarily with mild traumatic brain injury (CS; n = 53), and non-compensation seeking patients with intractable seizures (NCS; n = 30). All patients in the NCS sample scored in the "valid" range on the VSVT difficult memory items, compared to only 58.5% of the CS sample. We also identified VSVT measures and cut-off scores maximally efficient in discriminating these samples. This study confirms previous research that non-compensation seeking patients do well on the VSVT, but that many compensation seeking patients perform poorly on this measure.

Reduced-order modeling for hyperthermia: an extended balanced-realization-based approach.

Accurate thermal models are needed in hyperthermia cancer treatments for such tasks as actuator and sensor placement design, parameter estimation, and feedback temperature control. The complexity of the human body produces full-order models which are too large for effective execution of these tasks, making use of reduced-order models necessary. However, standard balanced-realization (SBR)-based model reduction techniques require a priori knowledge of the particular placement of actuators and sensors for model reduction. Since placement design is intractable (computationally) on the full-order models, SBR techniques must use ad hoc placements. To alleviate this problem, an extended balanced-realization (EBR)-based model-order reduction approach is presented. The new technique allows model order reduction to be performed over all possible placement designs and does not require ad hoc placement designs. It is shown that models obtained using the EBR method are more robust to intratreatment changes in the placement of the applied power field than those models obtained using the SBR method.

Optimal actuator placement for large scale systems: a reduced-order modelling approach.

A recently developed, extended balanced realization, reduced order modelling technique for large-scale distributed systems is applied to the problem of optimal actuator placement for hyperthermia treatments. Extended balanced realization develops low-order models whose state reconstructions are robust to actuator and sensor placement changes, and hence can be effectively used to find optimal placements in a computationally efficient manner. This optimization approach has been tested on simulations of a scanned focused, ultrasound hyperthermia system and found to be robust and accurate over a wide range of models, and the savings in computational costs were found to be significant.

A comparison of reduced-order modelling techniques for application in hyperthermia control and estimation.

Reduced-order modelling techniques can make important contributions in the control and state estimation of large systems. In hyperthermia, reduced-order modelling can provide a useful tool by which a large thermal model can be reduced to the most significant subset of its full-order modes, making real-time control and estimation possible. Two such reduction methods, one based on modal decomposition and the other on balanced realization, are compared in the context of simulated hyperthermia heat transfer problems. The results show that the modal decomposition reduction method has three significant advantages over that of balanced realization. First, modal decomposition reduced models result in less error, when compared to the full-order model, than balanced realization reduced models of similar order in problems with low or moderate advective heat transfer. Second, because the balanced realization based methods require a priori knowledge of the sensor and actuator placements, the reduced-order model is not robust to changes in sensor or actuator locations, a limitation not present in modal decomposition. Third, the modal decomposition transformation is less demanding computationally. On the other hand, in thermal problems dominated by advective heat transfer, numerical instabilities make modal decomposition based reduction problematic. Modal decomposition methods are therefore recommended for reduction of models in which advection is not dominant and research continues into methods to render balanced realization based reduction more suitable for real-time clinical hyperthermia control and estimation.

Neutral endopeptidase regulates C-type natriuretic peptide metabolism but does not potentiate its bioactivity in vivo.

C-type natriuretic peptide (CNP) is a newly described 22-amino acid peptide of endothelial and renal cell origin with selective cardiovascular actions. Recent in vitro studies have reported that CNP is the most susceptible of all natriuretic peptides to enzymatic degradation by neutral endopeptidase 24.11 (NEP). The present study was undertaken to define the role of NEP in total and regional CNP metabolism and the modulatory actions of NEP inhibition on the biological actions of CNP. CNP (10 ng x kg(-1) x min(-1)) followed by candoxatrilat (240 microg x kg(-1) bolus and 8 microg x kg(-1) x min(-1)), a potent and selective NEP inhibitor, was administered intravenously to a group of anesthetized mongrel dogs (group 1) to permit calculation of total metabolic clearance rate (MCR); results were compared with those in a group receiving vehicle infusion followed by candoxatrilat (group 2; both groups, n=7). NEP inhibition increased circulating CNP achieved by exogenous infusion and reduced total MCR in group 1. The regional CNP MCRs increased after CNP administration. While the pulmonary MCR did not change during concomitant candoxatrilat infusion, renal MCR was suppressed. Hemodynamic changes were not different between groups. A mild natriuretic and diuretic effect in association with an increase in circulating and urinary ANP levels was not different between groups. Urinary CNP excretion did not change with CNP infusion but markedly increased after NEP inhibition. We conclude that (1) circulating CNP achieved by exogenous CNP infusion is regulated by NEP in vivo, (2) regional MCRs are heterogeneous with NEP inhibition, (3) NEP inhibition does not potentiate acute cardiovascular actions of CNP, and (4) a mild natriuretic and diuretic effect observed with CNP and NEP inhibition may be ANP dependent.

Angiotensin converting enzyme inhibition modulates endogenous endothelin in chronic canine thoracic inferior vena caval constriction.

Endothelin (ET) is a potent vasoconstrictor peptide which is elevated in plasma in congestive heart failure. Recent studies suggest an important role for angiotensin II (AII) in the activation of ET in cultured cardiomyocytes. Chronic thoracic inferior vena caval constriction (TIVCC) is a model of reduced cardiac output that mimics the neurohumoral activation observed in congestive heart failure. We hypothesized that activation of the renin-angiotensin system in TIVCC plays a role in the activation of ET and that the elevation of endogenous ET contributes to the systemic and renal vasoconstriction that characterizes this model of venous congestion. We studied conscious dogs after 7 d of TIVCC in the presence or absence of chronic angiotensin converting enzyme inhibition with enalapril. TIVCC resulted in marked activation of plasma AII and ET in plasma, right atrium, lung, and renal medulla which was further localized to cardiomyocytes, pulmonary, and renal epithelial cells. Chronic angiotensin converting enzyme inhibition abolished the increases in plasma AII and ET during TIVCC. Acute endothelin A receptor blockade with FR-139317 resulted in significant decreases in mean arterial pressure and systemic vascular resistance in TIVCC. We conclude that activation of the renin-angiotensin system contributes to the activation of circulating and local ET in TIVCC and that this activation plays an important role in the regulation of arterial pressure and systemic vascular resistance in this model of congestive failure.

Presence and secretion of atrial natriuretic peptide from cultured human aortic endothelial cells.

The endothelium is the production site of several potent vasoactive substances that modulate vascular tone and growth. The present study was undertaken to investigate the presence and secretion of atrial natriuretic peptide (ANP) immunoreactivity from vascular endothelial cells. ANP immunoreactivity was present in cultured human aortic endothelial cells by both immunohistochemical staining and radioimmunoassay. ANP immunoreactivity was also detectable in culture medium from human aortic endothelial cells in low picogram concentrations. These findings suggest that vascular endothelium is a site of ANP production and secretion of ANP. There was a differential distribution of ANP and endothelin-1 (ET-1), with a higher ANP concentration in cell extracts and a higher ET-1 concentration in cell culture media. Although ANP has been conceived as a circulating endocrine hormone, these findings are consistent with ANP functioning also as an autocrine and paracrine modulator in the regulation of vascular tone and growth.

Presence of C-type natriuretic peptide in human kidney and urine.

The current study was undertaken to investigate the presence of CNP immunoreactivity in both human kidney and urine. Immunohistochemical staining with an indirect immunoperoxidase method utilizing an antibody which is 100% cross-reactive to both CNP-53 and CNP-22 was performed on five human kidney specimens (three biopsies of normal cadaveric donor kidneys and two of normal autopsy specimens). CNP immunoreactivity was positive in proximal, distal and medullary collecting duct tubular cells in a cytoplasmic and granular staining pattern. CNP immunoreactivity was also determined in the urine of five healthy volunteers utilizing a sensitive and specific double-antibody radioimmunoassay with a mean concentration of 10.8 +/- 1.0 pg/ml. With the utilization of high pressure liquid chromatography, this immunoreactivity proved to be consistent with both the low molecular weight form, CNP-22, as well as the high molecular weight form, CNP-53. Urinary excretion of CNP was also measured in normal subjects (N = 5) and in patients with congestive heart failure (CHF, N = 6). CHF patients excreted over three times more CNP than normals (27.2 +/- 2.8 vs. 8.7 +/- 0.81 pg/min, P < 0.004) despite no difference between the two groups in plasma CNP concentrations (6.97 +/- 0.28 vs. 8.08 +/- 1.52 pg/ml, P = NS). This study demonstrates for the first time the presence of CNP immunoreactivity in human kidney and suggests that renal tubular cells may be an additional non-vascular site of synthesis for this cardiorenal acting peptide. This study also demonstrates an increase in urinary CNP excretion in congestive heart failure.

Liver-lung interactions during E. coli endotoxemia. TNF-alpha:leukotriene axis.

The liver modulates host responses to endotoxemia by production and clearance of tumor necrosis factor alpha (TNF-alpha) and eicosanoid lipoxygenation products. Reductions in liver blood flow (QL) are common during endotoxemia, but it is unknown whether the kinetics of TNF-alpha and leukotrienes (LTs) are thereby altered to amplify lung inflammation. To test this hypothesis, reductions in QL were modeled by an end-to-side portacaval shunt (PCS) in Sprague-Dawley rats. Conscious animals received 2.5 mg/kg of intravenous E. coli lipopolysaccharide (LPS) serotype 055:B5 (PCS + LPS; n = 17) or saline (n = 5). Responses were compared with those in sham-operated rats (sham + LPS; n = 13) and NSS-challenged control rats (n = 5). Cardiopulmonary changes, serum TNF-alpha, and formed elements were determined at t = 0, 1.5, 3.5, and 24 h, when organ wet/dry ratios (W/D) were measured with TNF-alpha, LTB4, and polymorphonuclear neutrophils (PMN) in bronchoalveolar lavage fluid (BALF). In PCS + LPS rats, mortality was 59% and serum TNF-alpha peaked at 1.5 h (2,784 +/- 658 U/ml, mean +/- SEM) coincident with the onset of hypotension. Despite equivalent endotoxemia and liver- and lung-associated TNF-alpha in sham + LPS rats at 1.5 h, peak serum TNF-alpha was 38% less and mortality was 15% (p < 0.05). Cardiac, hepatic, and cecal W/D were likewise increased in PCS + LPS versus sham + LPS rats, as were BALF PMNs (p < 0.05). In parallel studies, the disappearance kinetics of infused rTNF-alpha were not altered in nonendotoxemic PCS animals, implicating enhanced lung uptake of LPS and systemic export of TNF-alpha in PCS + LPS rats.(ABSTRACT TRUNCATED AT 250 WORDS)

A recombinant factor VIII A2 domain polypeptide quantitatively neutralizes human inhibitor antibodies that bind to A2.

Human antibodies that inactivate coagulation factor VIII (fVIII), known as inhibitors, have been shown by immunoblotting or immunoprecipitation assays to bind predominantly to epitopes within the A2 and/or C2 domains of the fVIII protein. Because these assays simply measure antibody binding, a soluble recombinant polypeptide containing the fVIII A2 domain was used to develop a quantitative inhibitor neutralization assay for antibodies that bound only to A2 by immunoblotting assay. Antibodies from six of eight inhibitor plasmas were fully neutralized by A2 (> or = 90%), whereas two were only partially neutralized. These results established the fVIII inhibitor properties of anti-A2 antibodies. In immunoprecipitation assays, five of the eight inhibitors also had significant levels of anti-light-chain antibody. In one case, this light-chain antibody was shown to have inhibitor activity. Because it did not bind to the C2 domain, this antibody appears to define a new inhibitor epitope within the fVIII light chain. Another inhibitor, which was partially neutralized by A2, was not neutralized by the light chain, even though it contained anti-light-chain antibodies by immunoprecipitation assay. Our results show additional complexities of the immune response to fVIII.

Promotion of murine B cell differentiation by 2-mercaptoethanol in contrast to glutathione.

The role of thiol compounds in B cell proliferation and differentiation was investigated with a stable, homogeneous population of an antigen-specific plasmablastoma, 2C3. This cell line expresses both membrane and secreted forms of immunoglobulin and is arrested at an intermediate stage of B cell development. Attempts to induce its differentiation into plasma cells using antigen, anti-idiotypic antibodies, or mitogens were unsuccessful. However, cultivation of 2C3 in the presence of 2-mercaptoethanol (5 x 10(-5) M) changed its doubling time from 19.8 to 34.9 h. There was also a significant rise in intracellular glutathione and in immunoglobulin production, but little change in non-Ig protein secretion. In contrast, exposure of 2C3 to exogenous glutathione (5 x 10(-3) M) reduced the doubling time to 11.0 h, with marked increases in proliferation. Moreover, there was no significant rise in either intracellular glutathione or immunoglobulin secretion. Distinct morphological differences were also apparent at the ultrastructural level. Thus, there is a dichotomy in the action of the two thiols. Although the effects of 2-mercaptoethanol could not be reversed, the two thiols together abrogated each other's effects, implying that their actions may be mediated through a common regulatory pathway.

A soluble recombinant factor VIII fragment containing the A2 domain binds to some human anti-factor VIII antibodies that are not detected by immunoblotting.

Human factor VIII (fVIII) inhibitors are pathologic antibodies that inactivate fVIII. A cDNA clone was modified to encode fVIII amino acid residues 373-740 for expression in a baculovirus vector in insect cells. The encoded protein fragment H2 was produced as a soluble, secreted protein, and it was used to test inhibitor plasmas for the presence of antibodies that were not detected by immunoblotting. Seven of 13 inhibitors that bound only to the fVIII light chain by immunoblotting also bound to fragment H2 in an immunoprecipitation assay. Thus multi-chain inhibitor reactivity of inhibitors is more frequent than previously reported. One of these inhibitors was shown to share the epitope for other inhibitors that bind to H2 within amino acid residues 373-541 in immunoblotting assays. The sensitive immunoprecipitation assay described allows determination of relative H2 binding capacity of the total IgG and epitope localization of inhibitors that cannot be similarly characterized by immunoblotting.

Magnetic resonance imaging of lipid deposits in human atheroma via a stimulated-echo diffusion-weighted technique.

NMR images of subintimal lipid deposits within the vessel walls of atherosclerotic human aortas were obtained at 37 and 27 degrees C at 4.7 T. A combination of a stimulated-echo and pulsed-field gradients was used for suppressing the mobile tissue water relative to the less mobile tissue lipids. At 27 degrees C there was also a substantial reduction of the subintimal lipid signal intensity, which is consistent with the characteristic phase transition of cholesteryl esters in human atheroma. These results represent the first direct detection of lipid deposits in nonprotruding atherosclerotic lesions with NMR imaging.

Decreased cell membrane magnesium in some essential hypertension patients.

The concentrations of total ([T-Mg]), ultrafilterable ([UF-Mg]), and protein-bound or nonfilterable ([NF-Mg]) magnesium were measured in the plasma and in the intracellular compartment of blood from 8 essential hypertensive patients and 9 normotensive subjects. In the former, [T-Mg] was unchanged in the plasma but decreased in whole blood due to decreases of both [UF-Mg] and [NF-MG]; [UF-Mg] was increased in plasma but decreased intracellularly while [NF-Mg] was decreased in plasma and unchanged intracellularly. These concentrations correlated significantly with the average blood pressures. Decreased Mg binding to the erythrocyte membrane was also observed in 13 additional essential hypertensive patients. This decreased binding may well be responsible for the decreased intracellular [UF-Mg] in the blood of such patients. The cause of the decreased Mg binding to the erythrocyte membrane is unknown, but the binding is returned to normal by incubating erythrocytes from essential hypertensive patients with blood plasma from normotensive subjects. Decreased Mg binding to cell membranes must also occur in frankly Mg-deficient patients, some of whom, as a consequence of the primary deficiency of this mineral, are hypertensive. Normal Mg binding to erythrocyte membranes was observed in two patients with hypertension indicating that hypertension per se does not cause decreased Mg binding to cell membranes. These observations suggest that decreased Mg binding to cell membranes may be an important contributing factor in some cases of essential hypertension.

Analysis of diabetic cataractogenesis using chemical-shift nuclear magnetic resonance microscopy.

We here report the analysis of single rabbit lenses under high-glucose stress using four-dimensional 13C nuclear magnetic resonance (NMR) spectroscopy (three spatial and one chemical-shift). We have produced spatial maps of lenticular metabolites (glucose, sorbitol, and lactate) with submillimeter in-plane resolution. The production of sorbitol and its inhibition are also presented. This is the first study to report regional tissue metabolism. We expect further improvements in spatial resolution and acquisition times that will enable localized kinetic studies in intact tissues.