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PubMed2004

Residual behavioral and neuroanatomical effects of short-term chronic ethanol consumption in rats.

The residual effects of short-term chronic ethanol consumption were investigated in rats maintained on an ethanol liquid diet for 26 consecutive days (mean intake = 16.1 g/kg/day). Animals were assessed for spontaneous motor activity (12 days post-ethanol), spatial working memory (17 days post-ethanol), spatial reference memory (184 days post-ethanol), and retention of passive avoidance (201 days post-ethanol). Measurements of brain weights and cortical thickness vertices within the dorsomedial and ventrolateral cortex of eight coronal planes were determined 260 days post-ethanol. Two-dimensional cell profile densities within six coronal planes and within CA1 region of the hippocampus were also obtained, along with the total volumetric measurement of the hippocampus proper. Results indicated between group differences when subjects were assessed on working memory with ethanol-treated animals exhibiting longer escape latencies in a Morris water maze, an effect partially attributed to the perseverance of ethanol-treated animals in exhibiting thigmotaxicity. No other ethanol-related behavioral impairment was noted. Neuroanatomically, ethanol-treated rats had thinner cortical mantles (6.3% and 6.6% reductions) within the frontoparietal cortex and had lower two-dimensional cell profile densities within the most caudal cortical region studied. Interestingly, control animals with thicker cortical mantles tended to perform better on the working memory task, whereas the opposite was true for ethanol-treated subjects. These data led to the conclusion that chronic ethanol consumption of a relatively short duration produces working memory impairments, albeit mild, that are partially related to an inability to abandon ineffectual behavioral strategies, and also produces neuroanatomical alterations within the cortex.

Alcohol Drinking↗
PubMed2001

Deciphering the genetic architecture of a multivariate phenotype.

A heritable multivariate quantitative phenotype comprises several correlated component phenotypes that are usually pleiotropically controlled by a set of major loci and environmental factors. One approach to decipher the genetic architecture of a multivariate phenotype, in particular to map the underlying loci, is to reduce the dimensionality of the data by means of a data reduction technique, such as principal component analysis. The extracted principal components are then analyzed in conjunction with marker data to map the underlying loci. We have examined the efficiency of this approach with and without taking into account the correlation structure of the multivariate phenotype when extracting principal components. We have assumed that genome-wide scan data on sibpairs are available for low-density (widely spaced) and high-density markers. Using extensive simulations, based on three models of the multivariate phenotype, we have shown that although ignoring the correlation structure of the multivariate phenotype does not have any serious impact on the efficiency of mapping the underlying trait loci in wide marker intervals, there is a significant adverse effect of this practice for fine-mapping. We, therefore, recommend that the correlation structure of the multivariate phenotype be carefully examined to decide on the strategy of extracting principal components for deciphering the genetic architecture of the multivariate phenotype.

Chromosome Mapping↗
PubMed2003

Radiation-induced second cancers: the impact of 3D-CRT and IMRT.

Information concerning radiation-induced malignancies comes from the A-bomb survivors and from medically exposed individuals, including second cancers in radiation therapy patients. The A-bomb survivors show an excess incidence of carcinomas in tissues such as the gastrointestinal tract, breast, thyroid, and bladder, which is linear with dose up to about 2.5 Sv. There is great uncertainty concerning the dose-response relationship for radiation-induced carcinogenesis at higher doses. Some animal and human data suggest a decrease at higher doses, usually attributed to cell killing; other data suggest a plateau in dose. Radiotherapy patients also show an excess incidence of carcinomas, often in sites remote from the treatment fields; in addition there is an excess incidence of sarcomas in the heavily irradiated in-field tissues. The transition from conventional radiotherapy to three-dimensional conformal radiation therapy (3D-CRT) involves a reduction in the volume of normal tissues receiving a high dose, with an increase in dose to the target volume that includes the tumor and a limited amount of normal tissue. One might expect a decrease in the number of sarcomas induced and also (less certain) a small decrease in the number of carcinomas. All around, a good thing. By contrast, the move from 3D-CRT to intensity-modulated radiation therapy (IMRT) involves more fields, and the dose-volume histograms show that, as a consequence, a larger volume of normal tissue is exposed to lower doses. In addition, the number of monitor units is increased by a factor of 2 to 3, increasing the total body exposure, due to leakage radiation. Both factors will tend to increase the risk of second cancers. Altogether, IMRT is likely to almost double the incidence of second malignancies compared with conventional radiotherapy from about 1% to 1.75% for patients surviving 10 years. The numbers may be larger for longer survival (or for younger patients), but the ratio should remain the same.

Adenocarcinoma↗
PubMed1998

In vitro verification of myocardial motion tracking from phase-contrast velocity data.

The ability to track motion from cine phase-contrast (PC) magnetic resonance (MR) velocity measurements was investigated using an in vitro model. A computer-controlled deformable phantom was used for the characterization of the accuracy and precision of the forward-backward and the compensated Fourier integration techniques. Trajectory accuracy is limited by temporal resolution when the forward-backward technique is used. With this technique the extent of the calculated trajectories is underestimated by an amount related to the motion period and the sequence repetition time, because of the band-limiting caused in the cine interpolation step. When the compensated Fourier integration technique is used, trajectory accuracy is independent of temporal resolution and is better than 1 mm for excursions of less than 15 mm, which are comparable to those observed in the myocardium. Measurement precision is dominated by the artifact level in the phase-contrast images. If no artifacts are present precision is limited by the inherent signal-to-noise ratio of the images. In the presence of artifacts, similar in magnitude to those observed in vivo, the reproducibility of tracking a 2.2 x 2.2 mm2 region of interest is better than 0.5 mm. When the Fourier integration technique is used, the improved accuracy is accompanied by a reduction in precision. We verified that tracking three-dimensional (3D) motion from velocity measurements of a single slice can lead to underestimations of the trajectory if there is a through-plane component of the motion that is not truly represented by the measured velocities. This underestimation can be overcome if volumetric cine phase-contrast velocity data are acquired and full three-dimensional analysis is performed.

Artifacts↗
PubMed1999

The influence of junction conformation on RNA cleavage by the hairpin ribozyme in its natural junction form.

In the natural form of the hairpin ribozyme the two loop-carrying duplexes that comprise the majority of essential bases for activity form two adjacent helical arms of a four-way RNA junction. In the present work we have manipulated the sequence around the junction in a way known to perturb the global folding properties. We find that replacement of the junction by a different sequence that has the same conformational properties as the natural sequence gives closely similar reaction rate and Arrhenius activation energy for the substrate cleavage reaction. By comparison, rotation of the natural sequence in order to alter the three-dimensional folding of the ribozyme leads to a tenfold reduction in the kinetics of cleavage. Replacement with the U1 four-way junction that is resistant to rotation into the antiparallel structure required to allow interaction between the loops also gives a tenfold reduction in cleavage rate. The results indicate that the conformation of the junction has a major influence on the catalytic activity of the ribozyme. The results are all consistent with a role for the junction in the provision of a framework by which the loops are presented for interaction in order to create the active form of the ribozyme.

Base Sequence↗
PubMed2000

Ligand influences of the structures of molybdenum oxide networks.

The influence of organonitrogen ligands on the network structure of molybdenum oxides was examined by preparing three new molybdenum oxide phases [MoO3(4,4'-bpy)0.5] (MOXI-8), [HxMoO3(4,4'-bpy)0.5] (MOXI-9), and [MoO3(triazole)0.5] (MOXI-32). The structure of [MoO3(4,4'-bpy)0.5) consists of layers of corner-sharing MoO5N octahedra, buttressed by bridging 4,4'-bipyridyl ligands into a three-dimensional covalently bonded organic-inorganic composite material. Partial reduction of [MoO3(4,4'-bpy)0.5] yields the mixed-valence material [HxMoO3(4,4'-bpy)0.5] (x approximately 0.5). The most apparent structural change upon reduction is found in the Mo-ligand bond lengths of the MoO5N octahedra, which exhibit the usual (2 + 2 + 2) pattern in [MoO3(4,4'-bpy)0.5] and a more regular (5 + 1) pattern in [HxMoO3(4,4'-bpy)0.5]. Substitution of triazole for 4,4'-bipyridine yields [MoO3(triazole)0.5], which retains the layer motif of corner-sharing MoO5N octahedra but with distinct sinusoidal ruffling in contrast to planar layers of [MoO3(4,4'-bpy)0.5] and [HxMoO3(4,4'-bpy)0.5]. The folding reflects the ligand constraints imposed by the triazole ligand that bridges adjacent Mo sites within a layer. MOXI-8, C5H4NMoO3: monoclinic P2(1)/c, a = 7.5727(6) A, b = 7.3675(7) A, c = 22.433(3) A, beta = 90.396(8) degrees, Z = 8. MOXI-9, C5H4.5NMoO3: monoclinic I2/m, a = 5.2644(4) A, b = 5.2642(4) A, c = 22.730(2) A, beta = 90.035(1) degrees, Z = 4. MOXI-32, C2H3N3Mo2O6: orthorhombic Pbcm, a = 3.9289(5) A, b = 13.850(2) A, c = 13.366(2) A, Z = 4.

Journal Article↗
PubMed2002

The catalytic pathway of horseradish peroxidase at high resolution.

A molecular description of oxygen and peroxide activation in biological systems is difficult, because electrons liberated during X-ray data collection reduce the active centres of redox enzymes catalysing these reactions. Here we describe an effective strategy to obtain crystal structures for high-valency redox intermediates and present a three-dimensional movie of the X-ray-driven catalytic reduction of a bound dioxygen species in horseradish peroxidase (HRP). We also describe separate experiments in which high-resolution structures could be obtained for all five oxidation states of HRP, showing such structures with preserved redox states for the first time.

Catalysis↗
PubMed1989

Saposin A: second cerebrosidase activator protein.

Saposin A, a heat-stable 16-kDa glycoprotein, was isolated from Gaucher disease spleen and purified to homogeneity. Chemical sequencing from its amino terminus and of peptides obtained by digestion with protease from Staphylococcus aureus strain V-8 demonstrated that saposin A is derived from proteolytic processing of domain 1 of its precursor protein, prosaposin. Processing of prosaposin (70 kDa) also generates three other previously reported saposin proteins, B, C, and D, from its second, third, and fourth domains. Similar to saposin C, saposin A stimulates the hydrolysis of 4-methylumbelliferyl beta-glucoside and glucocerebroside by beta-glucosylceramidase and of galactocerebroside by beta-galactosylceramidase, mainly by increasing the maximal velocity of both reactions. Saposin A is as active as saposin C in these reactions. Saposin A has no significant effect on other sphingolipid and 4-methylumbelliferyl glycoside hydrolases tested. Saposin A has two potential glycosylation sites that appear to be glycosylated. After deglycosylation, saposin A had a subunit molecular mass of 10 kDa and was as active as native saposin A. However, reduction and alkylation abolished the activation. A three-dimensional model comparing saposins A and C reveals significant sequence homology between them, especially preservation of conserved acidic and basic residues in their middle regions. Each appears to possess a conformationally rigid hydrophobic pocket stabilized by three internal disulfide bridges, with amphipathic helical regions interrupted by helix breakers.

Amino Acid Sequence↗
PubMed2000

On the optimality of the gridding reconstruction algorithm.

Gridding reconstruction is a method to reconstruct data onto a Cartesian grid from a set of nonuniformly sampled measurements. This method is appreciated for being robust and computationally fast. However, it lacks solid analysis and design tools to quantify or minimize the reconstruction error. Least squares reconstruction (LSR), on the other hand, is another method which is optimal in the sense that it minimizes the reconstruction error. This method is computationally intensive and, in many cases, sensitive to measurement noise. Hence, it is rarely used in practice. Despite their seemingly different approaches, the gridding and LSR methods are shown to be closely related. The similarity between these two methods is accentuated when they are properly expressed in a common matrix form. It is shown that the gridding algorithm can be considered an approximation to the least squares method. The optimal gridding parameters are defined as the ones which yield the minimum approximation error. These parameters are calculated by minimizing the norm of an approximation error matrix. This problem is studied and solved in the general form of approximation using linearly structured matrices. This method not only supports more general forms of the gridding algorithm, it can also be used to accelerate the reconstruction techniques from incomplete data. The application of this method to a case of two-dimensional (2-D) spiral magnetic resonance imaging shows a reduction of more than 4 dB in the average reconstruction error.

Algorithms↗
PubMed1996

Glycosylation of recombinant ancrod from Agkistrodon rhodostoma after expression in mouse epithelial cells.

The thrombin-like serine protease ancrod from the Malayan pit viper Agkistrodon rhodostoma was expressed in mouse epithelial cells (C127). Oligosaccharide constituents were liberated from tryptic glycopeptides by treatment with peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase F. Neutral oligosaccharide alditols obtained after reduction and enzymic desialylation were separated by two-dimensional HPLC and characterized by methylation analysis, liquid secondary-ion mass spectrometry, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and sequential degradation with exoglycosidases. In contrast to natural ancrod, the recombinant glycoprotein carries exclusively diantennary, triantennary and tetraantennary N-glycans with Gal beta 4 GlcNAc beta (type-2) antennae which were, in part, further substituted by host-cell-specific structural elements such as Gal alpha 3 residues or N-acetyllactosamine repeats. As a characteristic feature, a substantial proportion of the oligosaccharides bears a GalNAc beta 4Glc-NAc antenna. Studies at the level of individual N-glycosylation sites demonstrated that glycans with N, N'-diacetyllactosediamine units are not specifically attached but occur at all sites in varying amounts. Hence, the putative recognition signal (Pro70-Lys-Lys) for glycoprotein hormone N-acetylgalactosaminyltransferase, present in this glycoprotein in close proximity to Asn79, does not convey site-specific transfer of GalNAc residues in these cells.

Agkistrodon↗
PubMed1991

Intracoronary urokinase in Kawasaki disease: treatment and prevention of myocardial infarction.

The main cause of death in Kawasaki disease is myocardial infarction due to thrombotic occlusion of a coronary aneurysm. Intracoronary thrombolytic treatment was performed in 15 patients with Kawasaki disease with giant coronary aneurysms. Three patients had acute myocardial infarction, four demonstrated silent myocardial infarction, three suffered chest pain and five did not show ischemia features but had massive thrombus in the coronary aneurysms. Urokinase was infused into the coronary aneurysms as a bolus of 8,000 to 10,000 units/kg via a catheter over 10 minutes. Partial but significant coronary recanalization was achieved after injection of urokinase in a patient with acute myocardial infarction. Complete resolution of massive intracoronary thrombi was observed in 3 of 15 patents, and partial resolution was recognized in 4 cases. In 7 patients, the size of thrombus did not change. Recurrence of the thrombus was observed in 4 patients by serial two-dimensional echocardiography. Urokinase was readministered and two showed significant reduction in the thrombus. All patients have been followed for more than 2 years with longest 8 years (mean: 3.3 yrs), and none have had a recurrence of myocardial infarction or died. These findings suggest that intracoronary urokinase is useful for the treatment and prevention of myocardial infarction in Kawasaki disease.

Child↗
PubMed2006

Does shade improve light interception efficiency? A comparison among seedlings from shade-tolerant and -intolerant temperate deciduous tree species.

Here, we tested two hypotheses: shading increases light interception efficiency (LIE) of broadleaved tree seedlings, and shade-tolerant species exhibit larger LIEs than do shade-intolerant ones. The impact of seedling size was taken into account to detect potential size-independent effects on LIE. LIE was defined as the ratio of mean light intercepted by leaves to light intercepted by a horizontal surface of equal area. Seedlings from five species differing in shade tolerance (Acer saccharum, Betula alleghaniensis, A. pseudoplatanus, B. pendula, Fagus sylvatica) were grown under neutral shading nets providing 36, 16 and 4% of external irradiance. Seedlings (1- and 2-year-old) were three-dimensionally digitized, allowing calculation of LIE. Shading induced dramatic reduction in total leaf area, which was lowest in shade-tolerant species in all irradiance regimes. Irradiance reduced LIE through increasing leaf overlap with increasing leaf area. There was very little evidence of significant size-independent plasticity of LIE. No relationship was found between the known shade tolerance of species and LIE at equivalent size and irradiance.

Microclimate↗
PubMedDate not supplied

Random sampling for evaluating treatment plans.

We analyze the influence of sampling technique on the accuracy of estimating irradiated volumes, dose-volume histograms and tumor control and normal tissue complication probabilities. The sampling techniques we consider are uniform distribution of points on a regular Cartesian grid and random selection of points. For three-dimensional treatment planning, random sampling leads to a significant reduction in estimation error and/or in the number of calculation points necessary to achieve a required accuracy. We discuss advantages and drawbacks of random sampling, as compared to sampling on a regular grid. It is suggested that, in practical situations, at least 50 times fewer randomly sampled points per organ/volume of interest are needed for fast estimation of complication probability with the same accuracy, i.e., not exceeding 5% (within 95% confidence limits) in the worst case.

Evaluation Studies as Topic↗
PubMed2000

Magnetic resonance imaging of thermal coagulation effects in a phantom for calibrating thermal therapy devices.

A material has been developed and tested that permanently records thermal response patterns from heating devices. The material consists of a mixture of polyacrylamide and 18% w/w bovine serum albumin. Thermal denaturation is complete when the local temperature exceeds 70 degrees C, causing a large reduction in the T2 of the material. Three-dimensional distributions of "thermal damage" can be assessed using standard magnetic resonance imaging sequences. The material works well with microwave heating devices and is adaptable for use with ultrasound, radio-frequency, or laser heating devices. Suggested uses include characterizing heating devices prior to treatment and developing new clinical applications for thermal therapies.

Acrylic Resins↗
PubMed1983

Protease production by Pseudomonas aeruginosa isolates from patients with cystic fibrosis.

The temporal appearance of extracellular proteases produced by Pseudomonas aeruginosa was analyzed by pH 9 and pH 4 polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE. Ammonium sulfate precipitates of culture supernatants from various stages of growth revealed a time-dependent increase in number and amount of proteolytically active proteins. One mucoid P. aeruginosa clinical isolate and its derived nonmucoid variant, as well as two other nonmucoid variant P. aeruginosa strains (all from cystic fibrosis patients), showed similar production of five differently migrating proteases (P1 to P5, numbered according to increasing net negative charge) in pH 9 PAGE and one protease in pH 4 PAGE. P2, P3, and P5 increased to maximum concentrations at 24 to 48 h, decreasing thereafter, whereas P4 continued increasing even at 83 h, and P1 fluctuated. P3 was identified as an elastase. P2 was possibly composed of polypeptide chains bridged by disulfide bonds, since without reduction it migrated in sodium dodecyl sulfate-PAGE as a single protein, and with reduction it migrated as three protein bands. Two-dimensional PAGE revealed multiple molecular weight species within protease-positive bands in pH 9 gel strips. Isoelectric focusing gave a pattern of protein separation that correlated with two-dimensional PAGE analysis. Thus, greater heterogeneity of active proteases than previously reported has been demonstrated in all P. aeruginosa clinical isolates studied by sensitive two-dimensional PAGE analysis.

Cystic Fibrosis↗
PubMed1992

Capsule structure of Proteus mirabilis (ATCC 49565).

Proteus mirabilis 2573 (ATCC 49565) produces an acidic capsular polysaccharide which was shown from glycose analysis, carboxyl reduction, methylation, periodate oxidation, and the application of one dimensional and two-dimensional high-resolution nuclear magnetic resonance techniques to be a high-molecular-weight polymer of branched trisaccharide units composed of 2-acetamido-2-deoxy-D-glucose (N-acetyl-D-glucosamine), 2-acetamido-2,6-dideoxy-L-galactose (N-acetyl-L-fucosamine), and D-glucuronic acid, having the structure: [formula: see text] P. mirabilis 2573 also produces an O:6 serotype lipopolysaccharide in which the O-chain component has the same structure as the homologous capsular polysaccharide. This is the first report of a defined capsular polysaccharide in this bacterial genus.

Carbohydrate Sequence↗
PubMed1994

Neuronal selectivities to complex object features in the ventral visual pathway of the macaque cerebral cortex.

1. To infer relative roles of cortical areas at different stages of the ventral visual pathway, we quantitatively examined visual responses of cells in V2, V4, the posterior part of the inferotemporal cortex (posterior IT), and the anterior part of the inferotemporal cortex (anterior IT), using anesthetized macaque monkeys. 2. The critical feature for the activation was first determined for each recorded cell by using a reduction method. We started from images of three-dimensional complex objects and simplified the image of effective stimuli step by step by eliminating a part of the features present in the image. The simplest feature that maximally activated the cell was determined as the critical feature. The response to the critical feature was then compared with responses of the same cell to a routine set of 32 simple stimuli, which included white and black bars of four different orientations and squares or spots of four different colors. 3. Cells that responded maximally to particular complex object features were found in posterior IT and V4 as well as in anterior IT. The cells in posterior IT and V4 were, however, different from the cells in anterior IT in that many of them responded to some extent to some simple features, that the size of the receptive field was small, and that they intermingled in single penetrations with cells that responded maximally to some simple features. The complex critical features in posterior IT and V4 varied; they consisted of complex shapes, combinations of a shape and texture, and combinations of a shape and color. 4. We suggest that local neuronal networks in V4 and posterior IT play an essential role in the formation of selective responses to complex object features.

Animals↗
PubMed1990

Identification of a novel integrin beta subunit expressed on cultured monocytes (macrophages). Evidence that one alpha subunit can associate with multiple beta subunits.

The vitronectin receptor (VnR) is one member of a subset of cell adhesion receptors within the integrin supergene family which shares the beta 3 subunit (IIIa). We show here that the VnR is absent from the surface of monocytes freshly isolated from blood but is expressed on these cells after a period of in vitro culture. Such cultured monocytes (macrophages) from a patient with type I Glanzmann's thrombasthenia, however, failed to express the VnR. Instead, immunoprecipitation with a monoclonal antibody directed to the VnR alpha chain (alpha v) revealed a novel integrin comprising alpha v associated noncovalently with a 100-kDa beta subunit (beta 3b), immunologically unrelated to the VnR beta subunit (beta 3a). This same novel integrin complex was also identified on 10-day-old macrophages from healthy donors, but on these cells, the beta 3b subunit was co-expressed with the classical VnR complex of alpha v beta 3a. The novel beta 3b subunit was not identified by monoclonal or polyclonal antibodies to IIIa (beta 3a) nor by a monoclonal antibody to the classical VnR complex. The beta 3b subunit could be distinguished from beta 3a by its relatively greater migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis after reduction, by its distinct isoelectric point upon two-dimensional gel electrophoresis, and by one-dimensional peptide mapping. Neither platelets nor B lymphoblasts from this patient with Glanzmann's thrombasthenia expressed any VnR on their surface, whereas control cells from a normal donor expressed the classical VnR but not the beta 3b subunit. The two beta chains, and hence also the combined receptor complexes, appeared to be differentially regulated. These findings provide the first example of an integrin alpha chain complexed with more than a single beta chain in the same cell. Furthermore, the differential regulation of expression of the different beta subunits that associate with the VnR alpha chain on cultured monocytes suggests a role for the novel receptor complex during monocyte/macrophage differentiation.

Adult↗