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PubMed1995

Concurrent presence of inv(14)(q11q32) and t(4;11)(q21;q23) in pre-B acute lymphoblastic leukemia.

The inv(14)(q11q32) is a non-random chromosomal aberration which has been associated with a variety of T-cell malignancies. We have studied a case of inv(14)(q11q32) that is unique in several respects. First, the inversion, which is expressed at the mRNA level, occurred in the context of a pre-B acute lymphoblastic leukemia (ALL) as opposed to a T-cell malignancy. Second, cloning and sequencing of the inversion revealed that it resulted from a fusion between an immunoglobulin heavy chain variable (V) segment and a T-cell receptor delta diversity (D) segment. In addition, the patient had a second chromosomal abnormality at diagnosis, a t(4;11)(q21;q23) which disrupted the MLL gene. The fact that there were two distinct chromosomal abnormalities at diagnosis enabled us to address the question of leukemic clonal evolution during the course of this patient's disease. We present evidence suggesting that the t(4;11)(q21;q23) occurred first, with the inv(14)(q11q32) occurring as a second event.

Acute Disease↗
PubMed2005

Fast oxygen-enhanced multislice imaging of the lung using parallel acquisition techniques.

The purpose of this study was to evaluate an optimized multislice acquisition technique for oxygen-enhanced MRI of the lung using slice-selective inversion and refocusing pulses in combination with parallel imaging. An inversion recovery HASTE sequence was implemented with respiratory triggering to perform imaging in end-expiration and with ECG triggering to avoid image acquisition during the systolic phase. Inversion pulses and the readout of echo trains could be interleaved to decrease acquisition time. The sequence was evaluated in 15 healthy volunteers, comparing three acquisition schemes: (1) acquisition of four slices without parallel imaging; (2) acquisition of four slices with parallel imaging; (3) acquisition of six slices with parallel imaging. These multislice acquisitions were repeated 80 times with alternating inhalation of room air and oxygen. The oxygen-induced signal increase showed no significant difference with and without parallel imaging. However, only with parallel imaging did the interleaved acquisition of six or more slices become possible, thus enabling a more complete anatomic coverage of the lung. The average required end-expiration time per repetition to acquire six slices could be significantly reduced from 4112 ms without to 2727 ms with parallel imaging. Total acquisition time varied between 8 and 13 min depending on the respiratory frequency.

Adult↗
PubMed1988

Common features of three inversions in wheat chloroplast DNA.

We have determined the DNA sequences of regions involved in two of the three inversions known to have occurred during the evolution of wheat chloroplast DNA. This establishes the extent of the second largest of the three inversions. Examination of these sequences suggests that although short repeated sequences are present, the endpoints of the second and third inversions are not associated with repeated sequences as long as those associated with the first inversion. However the endpoints of all three inversions are all adjacent to at least one tRNA gene, and there is evidence that three of the tRNA genes have been subjected to partial duplication, possibly at the time of inversion. This suggests that tRNA genes might be involved with rearrangements of chloroplast DNA, as has also been postulated for mitochondrial DNA.

Base Sequence↗
PubMed2002

Phase-sensitive inversion recovery for detecting myocardial infarction using gadolinium-delayed hyperenhancement.

After administration of gadolinium, infarcted myocardium exhibits delayed hyperenhancement and can be imaged using an inversion recovery (IR) sequence. The performance of such a method when using magnitude-reconstructed images is highly sensitive to the inversion recovery time (TI) selected. Using phase-sensitive reconstruction, it is possible to use a nominal value of TI, eliminate several breath-holds otherwise needed to find the precise null time for normal myocardium, and achieve a consistent contrast. Phase-sensitive detection is used to remove the background phase while preserving the sign of the desired magnetization during IR. Experimental results are presented which demonstrate the benefits of both phase-sensitive IR image reconstruction and surface coil intensity normalization for detecting myocardial infarction (MI). The phase-sensitive reconstruction method reduces the variation in apparent infarct size that is observed in the magnitude images as TI is changed. Phase-sensitive detection also has the advantage of decreasing the sensitivity to changes in tissue T(1) with increasing delay from contrast agent injection.

Artifacts↗
PubMed2005

Comparative analysis of MR sequences to detect structural brain lesions in tuberous sclerosis.

BACKGROUND: Tuberous sclerosis (TS) is a neurocutaneous genetically inherited disease with variable penetrance characterized by dysplasias and hamartomas affecting multiple organs. MR is the imaging method of choice to demonstrate structural brain lesions in TS. OBJECTIVE: To compare MR sequences and determine which is most useful for the demonstration of each type of brain lesion in TS patients. MATERIALS AND METHODS: We reviewed MR scans of 18 TS patients for the presence of cortical tubers, white matter lesions (radial bands), subependymal nodules, and subependymal giant cell astrocytoma (SGCA) on the following sequences: (1) T1-weighted spin-echo (T1 SE) images before and after gadolinium (Gd) injection; (2) nonenhanced T1 SE sequence with an additional magnetization transfer contrast medium pulse on resonance (T1 SE/MTC); and (3) fluid-attenuated inversion recovery (FLAIR) sequence. RESULTS: Cortical tubers were found in significantly (P<0.05) larger numbers and more conspicuously in FLAIR and T1 SE/MTC sequences. The T1 SE/MTC sequence was far superior to other methods in detecting white matter lesions (P<0.01). There was no significant difference between the T1 SE/MTC and T1 SE (before and after Gd injection) sequences in the detection of subependymal nodules; FLAIR sequence showed less sensitivity than the others in identifying the nodules. T1 SE sequences after Gd injection demonstrated better the limits of the SGCA. CONCLUSION: We demonstrated the importance of appropriate MRI sequences for diagnosis of the most frequent brain lesions in TS. Our study reinforces the fact that each sequence has a particular application according to the type of TS lesion. Gd injection might be useful in detecting SGCA; however, the parameters of size and location are also important for a presumptive diagnosis of these tumors.

Adolescent↗
PubMed2006

T1-weighted cine FLASH is superior to IR imaging of post-infarction myocardial viability at 4.7T.

PURPOSE: Data are unavailable for rational selection of pulse sequences to assess postinfarction myocardial viability in rodents at high field strength. We implemented a widely used clinical inversion recovery (IR) sequence at 4.7T and compared the results to a heavily T1-weighted cine FLASH sequence (T1-CF) for assessment of infarction size. MATERIALS AND METHODS: Eleven infarcted rats were examined within 24 h of infarction after injection of Gadophrin-3 contrast agent. Images were acquired using both pulse sequences and a standard cine (SC) sequence. Estimates of infarct size were compared to TTC. Global LV function was compared between the T1-CF and SC sequences. RESULTS: SNR, relative SNR, and CNR for the infarcted and normal myocardium were significantly greater for the IR sequence. Infarction size was overestimated by both sequences, but correlated highly and showed very close agreement with TTC. Global function revealed no significant differences between T1-CF and SC. CONCLUSION: Both IR and T1-CF produced reliable results for assessment of infarction size at 4.7T. While the IR sequence delivers better overall SNR and CNR, the T1-CF allows concomitant assessment of global cardiac function with a much shorter acquisition time.

Animals↗
PubMed1985

Early detection of canine myocardial infarction by magnetic resonance imaging in vivo.

This study was undertaken to assess the ability of proton magnetic resonance imaging (MRI) to detect myocardial ischemia shortly after coronary artery occlusion. Fifteen dogs were studied before and serially for up to 6 hr after anterior descending or circumflex coronary artery ligation in vivo by gated MRI with a 0.15 tesla resistive magnet (resonant frequency of hydrogen 6.25 MHz). Image acquisition was by single-spin echo, with echo times (TE) of 30 msec and TE 60 msec, and modified inversion recovery pulse sequences. Excellent anatomic definition was observed. By 4 hr after coronary artery occlusion the signal in the infarct zone increased to 36 +/- 20% greater than that in the adjacent normal myocardium for the TE 30 msec sequence (p less than .01) and to 116 +/- 100% for the TE 60 msec sequence (p less than .05). The most intense increase in signal was noted with the TE 60 msec pulse sequence and because normal myocardium is not well visualized by this technique, acutely ischemic myocardium was clearly delineated. Inversion recovery imaging did not show areas of ischemia. Changes seen on MR images correlated well with the location of ischemic changes noted on microscopic examination of the excised hearts. MRI thus provides a noninvasive means for detection of ischemia early in the course of myocardial infarction.

Animals↗
PubMed2003

Characterization and distribution of IS8301 in the radioresistant bacterium Deinococcus radiodurans.

The insertion sequence element IS8301 isolated from the radiation resistant bacterium Deinococcus radiodurans strain KD8301 was characterized. IS8301 is comprised of 1,736-bp, lacks terminal inverted repeats and does not duplicate target DNA upon its insertion. The amino acid sequence homology of two open reading frames encoded in IS8301 indicates that this insertion sequence element belongs to the IS200/IS605 group. There were seven loci completely identical with the IS8301 sequence in the published D. radiodurans R(1) genome sequence. The genome distribution profiles of IS8301 in strain KD8301 as well as in the three different laboratory isolates (KR(1), MR(1), and R(1)) of wild-type D. radiodurans were investigated using genomic hybridization analysis. At least 21 strong hybridization signals were detected in strain KD8301 while only one hybridization signal was detected in strain KR(1), the parent strain of KD8301. In strain MR1, a different wild-type isolate, six strong hybridization signals were detected. In spite of the identification of seven copies of IS8301 in the published D. radiodurans R(1) genome sequence, only one hybridization signal was detected in strain R(1) purchased from American Type Culture Collection. Using inverse PCR and sequencing analyses, total 13 different insertion loci of IS8301 in the D. radiodurans genome were identified. Sequence comparison of the flanking region of insertion sites indicated that the sequence 5'-TTGAT-3' preceded the left end of IS8301 in all cases.

Amino Acid Sequence↗
PubMed2000

Purification and characterization of the R64 shufflon-specific recombinase.

The shufflon, a multiple DNA inversion system in plasmid R64, consists of four invertible DNA segments which are separated and flanked by seven 19-bp repeat sequences. The product of a site-specific recombinase gene, rci, promotes site-specific recombination between any two of the inverted 19-bp repeat sequences of the shufflon. To analyze the molecular mechanism of this recombination reaction, Rci protein was overproduced and purified. The purified Rci protein promoted the in vitro recombination reaction between the inverted 19-bp repeats of supercoiled DNA of a plasmid carrying segment A of the R64 shufflon. The recombination reaction was enhanced by the bacterial host factor HU. Gel electrophoretic analysis indicated that the Rci protein specifically binds to the DNA segments carrying the 19-bp sequences. The binding affinity of the Rci protein to the four shufflon segments as well as four synthetic 19-bp sequences differed greatly: among the four 19-bp repeat sequences, the repeat-a and -d sequences displayed higher affinity to Rci protein. These results suggest that the differences in the affinity of Rci protein for the 19-bp repeat sequences determine the inversion frequencies of the four segments.

Bacterial Proteins↗
PubMed1988

Interactions between the promoter and first intron are involved in transcriptional control of alpha 1(I) collagen gene expression.

The first intron of the human collagen alpha 1(I) gene contains several positively and negatively acting elements. We have studied the transcription of collagen-human growth hormone fusion genes, containing deletions and rearrangements of collagen intronic sequences, by transient transfection of chick tendon fibroblasts and NIH 3T3 cells. In chick tendon fibroblasts, but not in 3T3 cells, inversion of intronic sequences containing a previously studied 274-base-pair segment, A274, resulted in markedly reduced human growth hormone mRNA levels as determined by an RNase protection assay. This inhibitory effect was largely alleviated when deletions were introduced in the collagen promoter of plasmids containing negatively oriented intronic sequences. Evidence for interaction of the promoter with the intronic segment, A274, was obtained by gel mobility shift assays. We suggest that promoter-intron interactions, mediated by DNA-binding proteins, regulate collagen gene transcription. Inversion of intronic segments containing critical interactive elements might then lead to an altered geometry and reduced activity of a transcriptional complex in those cells with sufficiently high levels of appropriate transcription factors. We further suggest that the deleted promoter segment plays a key role in directing DNA interactions involved in transcriptional control.

Chromosome Deletion↗
PubMed1994

Gene conversion is involved in the transfer of genetic information between naturally occurring inversions of Drosophila.

The DNA sequences of the ribosomal protein 49 (rp49) region were determined for 34 isochromosomal strains of Drosophila subobscura representing two chromosomal arrangements, the OST and the O3 + 4 gene arrangements, which differ by two overlapping inversions. The data reveal that gene conversion is a mechanism responsible for the transfer of genetic information between naturally occurring inversions of Drosophila. The estimated rate of gene transfer by gene conversion at this region, which is close to an inversion breakpoint, is lower than previous estimates obtained experimentally at the rosy (ry) gene in Drosophila melanogaster. Our data indicate that gene arrangements OST and O3 + 4 are monophyletic and rather old (0.58 and 0.73 million years old, respectively).

Animals↗
PubMed1994

Inverse polymerase chain reaction for cloning cellular sequences adjacent to integrated hepatitis B virus DNA in hepatocellular carcinomas.

Integration of hepatitis B virus (HBV) DNA is found in most HBV-related human hepatocellular carcinomas (HCCs). In the past, construction of genomic libraries was mainly employed to study the role of viral integration. However, large amounts of tissue DNA and a laborious screening procedures were required. Inverse polymerase chain reaction (IPCR) is based on the simple procedures of digestion of DNA with restriction enzymes and circularization of cleavage products before amplification using primers synthesized in the opposite orientations to those normally employed for PCR. This technique allows the in vitro amplification of DNA flanking a region of known sequence. By employing this method, starting from nanograms of hepatoma DNA, two adjacent cellular sequences were cloned from 11 HBV integrants in three HCCs. The original configurations in the chromosomes were further confirmed. One of the flanking cellular sequences was identified as the human 28S rRNA gene, the other was not found homologous to any known human sequences. This method appears to be practical and can be improved further to clone more flanking cellular sequences, especially in early and small HCCs.

Base Sequence↗
PubMed1998

Rump white inversion in the mouse disrupts dipeptidyl aminopeptidase-like protein 6 and causes dysregulation of Kit expression.

The mouse rump white (Rw) mutation causes a pigmentation defect in heterozygotes and embryonic lethality in homozygotes. At embryonic day (E) 7.5, Rw/Rw embryos are retarded in growth, fail to complete neurulation and die around E 9.5. The Rw mutation is associated with a chromosomal inversion spanning 30 cM of the proximal portion of mouse chromosome 5. The Rw embryonic lethality is complemented by the W19H deletion, which spans the distal boundary of the Rw inversion, suggesting that the Rw lethality is not caused by the disruption of a gene at the distal end of the inversion. Here, we report the molecular characterization of sequences disrupted by both inversion breakpoints. These studies indicate that the distal breakpoint of the inversion is associated with ectopic Kit expression and therefore may be responsible for the dominant pigmentation defect in Rw/+ mice; whereas the recessive lethality of Rw is probably due to the disruption of the gene encoding dipeptidyl aminopeptidase-like protein 6, Dpp6 [Wada, K., Yokotani, N., Hunter, C., Doi, K., Wenthold, R. J. & Shimasaki, S. (1992) Proc. Natl. Acad. Sci. USA 89, 197-201] located at the proximal inversion breakpoint.

Amino Acid Sequence↗
PubMed2006

USPIO-enhanced MR imaging for visualization of synovial hyperperfusion and detection of synovial macrophages: preliminary results in an experimental model of antigen-induced arthritis.

PURPOSE: To evaluate whether ultrasmall superparamagnetic iron particles (USPIO)-enhanced MRI is capable of assessing both synovial perfusion characteristics and the presence of synovial macrophages in a model of antigen-induced arthritis. MATERIALS AND METHODS: Unilateral arthritis was induced in six knees of six rabbits. The contralateral knees of the rabbits served as control knees. After onset of arthritis, all 12 knees were scanned prior to and immediately following intravenous administration of USPIO using a multiphase T1-weighted (T1w) fast gradient-echo (FGRE) sequence, and T1w spin-echo (SE), T2-weighted (T2w) FSE, T2*w GRE, and short-tau inversion recovery (STIR) sequences prior to and 24 hours following USPIO administration. SI-vs.-time curves (STCs) and the early enhancement rate during the first 56 seconds (REE(56)) were calculated from SI measurements within the synovial tissue of all knees on dynamic T1w images. MR findings were correlated to histopathology. RESULTS: REE(56) was significantly higher in the synovial tissue of arthritic knees than in the control knees (P < 0.01). Significant T1-, T2-, and T2* effects (P = 0.03-0.04) and multiple synovial vessels were visually detectable within the arthritic synovial tissue 24 hours after administration of USPIO, whereas no signal changes or synovial vessels were seen in the control knees. Histopathology revealed widened synovial blood vessels in the arthritic knees, and confirmed iron uptake by macrophages in the arthritic knees. CONCLUSION: USPIO-enhanced MRI is capable of both assessing synovial hyperperfusion and detecting macrophages in antigen-induced arthritis in rabbits.

Animals↗
PubMed1994

The STIR sequence MRI in the assessment of extraocular muscles in thyroid eye disease.

Nineteen patients with thyroid eye disease were examined with magnetic resonance imaging using the Short Tau Inversion Recovery (STIR) sequence and compared with normal controls. The Signal Intensity Ratio (SIR) of each of the four recti was obtained by comparison with the signal intensity of the adjacent temporalis muscle. The SIR was compared with disease activity assessed using Werner's grading system, a clinical inflammatory score, and the range of extraocular movements. Results show that a high SIR is associated with a high index of disease activity. This technique is likely to prove useful in assessing disease activity and planning the management of thyroid eye disease, particularly with respect to immunosuppression.

Adult↗
PubMed2004

[Determining myocardial viability in myocardial infarct. Comparison of single and multisclice MRI techniques with TurboFlash and TrueFISP sequences].

PURPOSE: The aim of the study was to compare the diagnostic accuracy in imaging viability of the myocardium with a multislice inversions recovery 2D single shot TrueFISP sequence and an established inversion recovery TurboFlash sequence. MATERIAL AND METHODS: Twelve patients with myocardial infarction were examined at a 1.5 tesla MR system (Sonata, Siemens, Medical Systems) 10 min after application of a single dose multihance (0,1 mmol/kg body weight) with a 2D multislice technique (inversion recovery single shot TrueFISP), that allows to image the entire short axis during one breathhold and a 2D single slice technique (inversion recovery TurboFlash), that requires one breathhold per slice. Signal intensity was determined in normal myocardium, in the infarcted myocardium and in the left ventricle. The contrast/noise ratio of normal and infarcted myocardium was determined. The areas of hyperintense infarction were compared for both sequence techniques. RESULTS: The multislice single shot 2D IR-TrueFisp sequence has a lower contrast/noise ratio than the IR-TurboFlash sequence (mean values 6.9 vs. 12.5) for viable and non viable myocardium. The assessment of the volume of the infarction is possible with excellent correlation of both techniques (r=0.97, p <0.036). In addition, an assessment of the transmural extent of the infarction is possible with identical spatial resolution. CONCLUSION: The inversions recovery 2D single shot TrueFisp technique allows for accurate detection of the infarction, for accurate determination of the area of the infarction and for assessment of the transmural extent of the infarction with high spatial resolution.

Adult↗
PubMed2000

Pulse inversion imaging of liver blood flow: improved method for characterizing focal masses with microbubble contrast.

RATIONALE AND OBJECTIVES: To create a microbubble contrast image of vessels that lie below the resolution of an ultrasound system, a technique is required that detects preferentially the agent echo, rejecting that from tissue. Harmonic imaging exploits the nonlinear behavior of microbubbles but forces a compromise between image sensitivity and axial resolution. The authors describe and evaluate a new method that overcomes this compromise and improves contrast imaging performance: pulse inversion imaging. METHODS: Sequences of pulses of alternate phase are transmitted into tissue and their echoes summed. A prototype scanner equipped with pulse inversion was used to image phantoms and 16 patients with focal liver masses. RESULTS: Pulse inversion images show contrast sensitivity and resolution superior to that of harmonic images. Vessels can be imaged at an incident power sufficiently low to avoid destroying the agent, allowing unique visualization of tumor vasculature. Distinct patterns were seen in hemangiomas, metastases, and hepatocellular carcinomas. CONCLUSIONS: Pulse inversion imaging is an improved bubble-specific imaging method that extends the potential of contrast ultrasonography.

Adult↗
PubMed1994

Amino acid sequence homology between Piv, an essential protein in site-specific DNA inversion in Moraxella lacunata, and transposases of an unusual family of insertion elements.

Deletion analysis of the subcloned DNA inversion region of Moraxella lacunata indicates that Piv is the only M. lacunata-encoded factor required for site-specific inversion of the tfpQ/tfpI pilin segment. The predicted amino acid sequence of Piv shows significant homology solely with the transposases/integrases of a family of insertion sequence elements, suggesting that Piv is a novel site-specific recombinase.

Amino Acid Sequence↗