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Biomedical subjects

J Ruff

Publications and source records attributed to J Ruff.

At least 19 recordsLinked to original sources
PubMed2004

Modern MRI tools for the characterization of acute demyelinating lesions: value of chemical shift and diffusion-weighted imaging.

Acute demyelinating lesions occur in various inflammatory disorders of the CNS. Apart from multiple sclerosis, most cases can be attributed to an overshooting immunological response to infectious agents called acute disseminated encephalomyelitis (ADEM). ADEM, which is mostly characterized by a monophasic course, has a multiphasic variant (MDEM). The early application of corticosteroids has been shown to be beneficial for the outcome; thus, an early diagnosis is highly desirable. Furthermore, the differential diagnosis ruling out neoplastic disorders may be difficult using conventional MRI alone. The potential diagnostic value of advanced MR techniques such as chemical shift imaging (CSI) and diffusion-weighted imaging (DWI) was investigated in a patient with MDEM, who had a new lesion in continuity with the initial disease manifestation. CSI was performed at 1.5 T with a long echo time of 135 ms for the evaluation of N-acetyl-aspartate (NAA) and choline (Cho) and with short TE of 30 ms for macromolecules (mm) and myo-Inositol (mI). DWI was performed using a single-shot isotropic EPI sequence. Whereas acute and chronic areas of demyelination were neither distinguishable on T2- nor on contrast-enhanced T1-weighted images, CSI and DWI revealed different metabolite concentrations and diffusion characteristics within the composite lesion, clearly separating acute from chronic areas of demyelination. In conclusion, the addition of CSI and DWI may add to the diagnostic power of MRI in the setting of demyelinating disorders by identifying areas of acute and chronic demyelination, even in the absence of contrast enhancement.

Adult↗
PubMed2001

Sulphoacetaldehyde sulpho-lyase (EC 4.4.1.12) from Desulfonispora thiosulfatigenes: purification, properties and primary sequence.

The strictly anaerobic bacterium Desulfonispora thiosulfatigenes ferments taurine via sulphoacetaldehyde, which is hydrolysed to acetate and sulphite by sulphoacetaldehyde sulpho-lyase (EC 4.4.1.12). The lyase was expressed at high levels and a two-step, 4.5-fold purification yielded an apparently homogeneous soluble protein, which was presumably a homodimer in its native form; the molecular mass of the subunit was about 61 kDa (by SDS/PAGE). The mass was determined to be 63.8 kDa by matrix-assisted laser-desorption ionization-time-of-flight (MALDI-TOF) MS. The purified enzyme converted 1 mol of sulphoacetaldehyde to 1 mol each of sulphite and acetate, but no requirement for thiamine pyrophosphate (TPP) was detected. The N-terminal and two internal amino acid sequences were determined, which allowed us to generate PCR primers. The gene was amplified and sequenced. The DNA sequence had no significant homologue in the databases searched, whereas the derived amino acid sequence indicated an oxo-acid lyase, revealed a TPP-binding site and gave a derived molecular mass of 63.8 kDa.

Amino Acid Sequence↗
PubMed2001

Dobutamine-stress magnetic resonance microimaging in mice : acute changes of cardiac geometry and function in normal and failing murine hearts.

The aim of this study was to assess the capability of MRI to characterize systolic and diastolic function in normal and chronically failing mouse hearts in vivo at rest and during inotropic stimulation. Applying an ECG-gated FLASH-cine sequence, MRI at 7 T was performed at rest and after administration of 1.5 microgram/g IP dobutamine. There was a significant increase of heart rate, cardiac output, and ejection fraction and significant decrease of end-diastolic and end-systolic left ventricular (LV) volumes (P<0.01 each) in normal mice during inotropic stimulation. In mice with heart failure due to chronic myocardial infarction (MI), MRI at rest revealed gross LV dilatation. There was a significant decrease of LV ejection fraction in infarcted mice (29%) versus sham mice (58%). Mice with MI showed a significantly reduced maximum LV ejection rate (P<0.001) and LV filling rate (P<0.01) and no increase of LV dynamics during dobutamine action, indicating loss of contractile and relaxation reserve. In 4-month-old transgenic mice with cardiospecific overexpression of the beta(1)-adrenergic receptor, which at this early stage do not show abnormalities of resting cardiac function, LV filling rate failed to increase after dobutamine stress (transgenic, 0.19+/-0.03 microL/ms; wild type, 0.36+/-0.01 microL/ms; P<0.01). Thus, MRI unmasked diastolic dysfunction during dobutamine stress. Dobutamine-stress MRI allows noninvasive assessment of systolic and diastolic components of heart failure. This study shows that MRI can demonstrate loss of inotropic and lusitropic response in mice with MI and can unmask diastolic dysfunction as an early sign of cardiac dysfunction in a transgenic mouse model of heart failure.

Adrenergic beta-Agonists↗
PubMed2001

Serial cine-magnetic resonance imaging of left ventricular remodeling after myocardial infarction in rats.

The purpose of the present study was the serial investigation of morphological and functional changes after left coronary artery ligation in the intact rat using cine-magnetic resonance imaging (MRI). MRI studies were performed 4, 8, 12, and 16 weeks after myocardial infarction (MI) with an echocardiogram (ECG)-triggered cine-fast low-angle shot (FLASH)-sequence in a 7-Tesla magnet. MI-size, left ventricular (LV) mass and volumes, cardiac index, ejection fraction (EF), and remote wall and scar thickness of 11 Wistar rats were compared to four sham-operated rats. Stress MRI with dobutamine (10 microl/kg x minute) was performed at 16 weeks. In MI groups (small MI < 30%, N = 5, large MI > 30%, N = 6), there was significant increase of LV mass (small MI + 47.8% increase, large MI + 74.1%) and wall thickness (large MI 1.21 +/- 0.03 to 1.84 +/- 0.07 mm). Scar thickness declined from four to 16 weeks (large MI 0.92 +/- 0.06 to 0.38 +/- 0.02 mm, P < 0.05). End-diastolic volume of both MI groups was significantly elevated but increased further only in animals with large MI from four to 16 weeks (657.1 +/- 38.6 to 869.7 +/- 60.7 microL, P < 0.05). Compared to sham, EF was significantly depressed in MI (large MI 31.5 +/- 2.0%). Wall thickening declined from four to 16 weeks post-MI (large MI 50.9 +/- 9.9 to 28.9 +/- 4.4%, P < 0.05). During stress, sham and MI rats increased wall thickening from 66.5 +/- 8.2 to 111.2 +/- 6.7% and from 30.8 +/- 4.3 to 47.5 +/- 5.8%, respectively (P < 0.05). Hypertrophy was found in all animals with MI throughout the entire period of observation, whereas dilatation after four weeks was only detected in animals with large MI. These morphologic changes were accompanied by an early decline of EF; myocardial function characterized by wall thickening deteriorated later.

Animals↗
PubMed2001

Map of the IncP1beta plasmid pTSA encoding the widespread genes (tsa) for p-toluenesulfonate degradation in Comamonas testosteroni T-2.

The catabolic IncP1beta plasmid pTSA from Comamonas testosteroni T-2 was mapped by subtractive analysis of restriction digests, by sequencing outwards from the tsa operon (toluenesulfonate degradation), and by generating overlapping, long-distance-PCR amplification products. The plasmid was estimated to comprise 72 +/- 4 kb. The tsa region was found to be a composite transposon flanked by two IS1071 elements. A cryptic tsa operon was also present in the tsa transposon. Those backbone genes and regions which we sequenced were in the same order as the corresponding genes in resistance plasmid R751, and identities of about 99% were observed. Enrichment cultures with samples from four continents were done to obtain organisms able to utilize p-toluenesulfonate as the sole source of carbon and energy for aerobic growth. Most (15) of the 16 cultures (13 of them isolates) were obtained from contaminated sites and were attributed to three metabolic groups, depending on their metabolism of p-toluenesulfonate. The largest group contained the tsa transposon, usually (six of seven isolates) with negligible differences in sequence from strain T-2.

Bacterial Proteins↗
PubMed2001

Dissimilatory sulfite reductase (desulfoviridin) of the taurine-degrading, non-sulfate-reducing bacterium Bilophila wadsworthia RZATAU contains a fused DsrB-DsrD subunit.

A dissimilatory sulfite reductase (DSR) was purified from the anaerobic, taurine-degrading bacterium Bilophila wadsworthia RZATAU to apparent homogeneity. The enzyme is involved in energy conservation by reducing sulfite, which is formed during the degradation of taurine as an electron acceptor, to sulfide. According to its UV-visible absorption spectrum with maxima at 392, 410, 583, and 630 nm, the enzyme belongs to the desulfoviridin type of DSRs. The sulfite reductase was isolated as an alpha2beta)gamma(n) (n > or = 2) multimer with a native size of 285 kDa as determined by gel filtration. We have sequenced the genes encoding the alpha and beta subunits (dsrA and dsrB, respectively), which probably constitute one operon. dsrA and dsrB encode polypeptides of 49 (alpha) and 54 kDa (beta) which show significant similarities to the homologous subunits of other DSRs. The dsrB gene product of B. wadsworthia is apparently a fusion protein of dsrB and dsrD. This indicates a possible functional role of DsrD in DSR function because of its presence as a fusion protein as an integral part of the DSR holoenzyme in B. wadsworthia. A phylogenetic analysis using the available Dsr sequences revealed that B. wadsworthia grouped with its closest 16S rDNA relative Desulfovibrio desulfuricans Essex 6.

Amino Acid Sequence↗
PubMed2000

Magnetic resonance imaging of coronary arteries and heart valves in a living mouse: techniques and preliminary results.

New investigations in MRI of a mouse heart showed high-contrast cardiac images and thereby the possibility of doing functional cardiac studies of in vivo mice. But is MRI, in addition, capable of visualizing microstructures such as the coronary arteries and the heart valves of a living mouse? To answer this question, 2D and 3D gradient echo sequences with and without flow compensation were used to image the coronary arteries. To increase signal-to-noise ratio, a birdcage resonator was optimized for mouse heart imaging. Contrast between blood and myocardium was achieved through the inflow effect. A segmented three-dimensional FLASH sequence acquired with a multiple overlap thin slab technique showed the best results. With this technique an isotropic resolution of 100 microm was achieved. The left coronary artery could be visualized up to the apex of the heart. This is demonstrated with short axis views and 3D surface reconstructions of the mouse heart. The four cardiac valves were also visible with the 3D method.

Algorithms↗
PubMed2000

Developmental changes of cardiac function and mass assessed with MRI in neonatal, juvenile, and adult mice.

Cardiovascular transgenic mouse models with an early phenotype or even premature death require noninvasive imaging methods that allow for accurate visualization of cardiac morphology and function. Thus the purpose of our study was to assess the feasibility of magnetic resonance imaging (MRI) to characterize cardiac function and mass in newborn, juvenile, and adult mice. Forty-five C57bl/6 mice from seven age groups (3 days to 4 mo after birth) were studied by MRI under isoflurane anesthesia. Electrocardiogram-gated cine MRI was performed with an in-plane resolution of (78-117 microm)(2). Temporal resolution per cine frame was 8.6 ms. MRI revealed cardiac anatomy in mice from all age groups with high temporal and spatial resolution. There was close correlation between MRI- and autopsy-determined left ventricular (LV) mass (r = 0.95, SE of estimate = 9.5 mg). The increase of LV mass (range 9.6-101.3 mg), cardiac output (range 1.1-14.3 ml/min), and stroke volume (range 3. 2-40.2 microl) with age could be quantified by MRI measurements. Ejection fraction and cardiac index did not change with aging. However, LV mass index decreased with increasing age (P < 0.01). High-resolution MRI allows for accurate in vivo assessment of cardiac function in neonatal, juvenile, and adult mice. This method should be useful when applied in transgenic mouse models.

Aging↗
PubMed2000

In vivo assessment of cardiac remodeling after myocardial infarction in rats by cine-magnetic resonance imaging.

The rat infarct model offers important parallels to the process of remodeling after myocardial infarction (MI) in humans. The aim of this study was to test the feasibility of cine fast low-angle shot (FLASH) magnetic resonance imaging (MRI) for assessment of the infarcted and noninfarcted rat heart and to compare the results with established methods. In group A, MRI was done 8-16 weeks after MI on a 7-T scanner using an electrocardiogram-triggered cine-FLASH sequence. We determined left ventricular (LV) volumes and mass, wall thickness, MI size, cardiac output, and ejection fraction. Afterward, MI size was histologically determined. In group B, after MRI eight controls and eight rats 16 weeks after MI underwent conventional hemodynamic measurements for determination of cardiac output, LV volumes, and ejection fraction by electromagnetic flowmeter and pressure-volume curves. LV wet weight was determined. In group A, MRI-acquired MI size (18.5 +/- 2%) was smaller than histology (22.8 +/- 2.5%, p < 0.05) with close correlation (r = 0.97). In group B, agreement in LV mass was found between MRI and wet weight (controls, 537.6 +/- 19.6 vs. 540.3 +/- 18.4 mg; MI, 865.1 +/- 39.2 vs. 865.1 +/- 41.3 mg; for the difference p = ns, r = 0.97, p < 0.05) and in the MRI and flowmeter measurements (cardiac output, controls 73.1 +/- 2.9 vs. 75.2 +/- 2.6 ml/min; MI 82.4 +/- 5.2 vs. 81.9 +/- 3.7 ml/min; for the difference p = ns, r = 0.80, p < 0.05). End-diastolic volume by MRI differed from pressure-volume curves with good correlation (controls, 343.9 +/- 8.4 vs. 262.7 +/- 12.8 microl; MI, 737.0 +/- 70.5 vs. 671.1 +/- 64.1 microl; p < 0.05 each, r = 0.96, p < 0.05). Cine-FLASH-MRI is a valuable diagnostic tool applicable to the rat model of MI. Being noninvasive and exact, it offers new insights in the remodeling process after MI because serial measurements are possible.

Animals↗
PubMed1999

Bioavailability of water-polluting sulfonoaromatic compounds.

Highly substituted arenesulfonates are chemically stable compounds with a range of industrial applications, and they are widely regarded as being poorly degradable. We did enrichment cultures for bacteria able to utilise the sulfonate moiety of 14 compounds, and we obtained mixed cultures that were able to desulfonate each compound. The products formed were usually identified as the corresponding phenol, but because we could not obtain pure cultures, we followed up these findings with quantitative work in pure cultures of, e.g., Pseudomonas putida S-313, which generated the same phenols from the compounds studied. Many of these phenols are known to be biodegradable, or to be subject to binding to soil components. We thus presume that the capacity to degrade aromatic sulfonates extensively is widespread in the environment, even though the degradative capacity is spread over several organisms and conditions.

Arylsulfonates↗
PubMed1998

Magnetic resonance microimaging for noninvasive quantification of myocardial function and mass in the mouse.

The purpose of this work was to develop high-resolution cardiac magnetic resonance imaging techniques for the in vivo mouse model for quantification of myocardial function and mass. Eight male mice were investigated on a 7-Tesla MRI scanner. High-quality images in multiple short axis slices (in-plane resolution 117 microm2, slice thickness 1 mm) were acquired with an ECG-gated cine sequence. Left ventricular end-diastolic and end-systolic volumes and mass were calculated from segmented slice volumes. There was precise agreement of left ventricular mass determined ex vivo and by MRI. Intraobserver (5%) and interobserver (5%) variability of in vivo MR measurements were low.

Animals↗
PubMed1994

Characterisation of two intronic nuclear-matrix-attachment regions in the human DNA topoisomerase I gene.

We identify two high-affinity matrix-attachment regions (MAR elements) located in two introns of the human DNA topoisomerase I gene (TOP1). These intronic MAR elements, designated MI and MII, are specifically bound by the nuclear matrix and partition with scaffolds in vitro. One of these MAR elements, MII, is part of a genomic region which is hypersensitive for endogenous nucleases. We have sequenced both DNA elements and have characterized their mode of binding to the nuclear matrix. Experiments with the minor-groove-binding ligands distamycin and chromomycin indicate that the A+T-rich regions, most likely homopolymeric A tracts, are responsible for binding of these DNA elements to the nuclear matrix. MII contains an alu-like element and a segment of curved DNA. Analysis of subfragments of MII show that the curved DNA region itself shows only weak nuclear-matrix binding, and that the high-affinity binding sites are located on subfragments on the 5' side of the curved DNA. In addition, we found that the alu-like sequence does not contribute significantly to the binding of MII and of subfragments of MII to nuclear-matrix proteins. Comparing the distribution of repetitive sequences in the cloned parts of human DNA topoisomerase I gene with the location of high-affinity matrix-binding sites we find no evidence that repetitive DNA may be located close to MAR elements as has been previously suggested.

Binding Sites↗
PubMed1993

A comparison of Teflon slides and the Army Insecticide Measuring System for sampling aerosol clouds.

The effects of method of droplet analysis, reader of Teflon slides and distance on mass median diameter of a Cythion aerosol cloud were examined in the calibration of an Army Insecticide Measuring System (AIMS). There were no significant differences in results among readers and between the AIMS and readers. There were slight but statistically significant differences between readers of Teflon slides and between the methods of analysis. Data supports the manufacturer's recommendation that, for the AIMS, the distance at which an aerosol generator air blast is between 3 and 7 m3 s-1 must be determined.

Aerosols↗
PubMed1991

DNA topoisomerase I cleavage sites in DNA and in nucleoprotein complexes.

The intracellular substrate for eukaryotic DNA topoisomerases is chromatin rather than protein-free DNA. Yet, little is known about the action of topoisomerases on chromatin-associated DNA. We have analyzed to what extent the organization of DNA in chromatin influences the accessibility of DNA molecules for topoisomerase I cleavage in vitro. Using potassium dodecyl sulfate precipitation (Trask et al., 1984), we found that DNA in chromatin is cleaved by the enzyme with somewhat reduced efficiency compared to protein-free DNA. Furthermore, using native SV40 chromatin and mononucleosomes assembled in vitro, we show that DNA bound to histone octamer complexes is cleaved by topoisomerase I and that the cleavage sites as well as their overall distribution are identical in histone-bound and in protein-free DNA molecules.

Base Sequence↗