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PubMed2005

Assessment of ventilation inhomogenity with Krypton SPECT and planar imaging.

In 29 chronic obstructive pulmonary disease (COPD) patients and nine lung healthy volunteers, above the age of 50 years, ventilation defects were examined by (81m)Kr planar scintigraphy and (81m)Kr single photon emission computed tomography (SPECT) to investigate if SPECT adds information regarding size and extent of visually scored ventilation defects, and to correlate the extent of defects obtained from the two imaging settings with standard pulmonary function tests performed in these patients/volunteers. For testing the reproducibility of the visual defect score of (81m)Kr scintigraphy additionally 13 patients suspected for pulmonary embolism or lung cancer were included. Each series of planar or SPECT studies were read for the extent (% abnormal lung) and severity (0-3) of ventilation abnormalities. Seventeen scans were read twice for reproducibility studies. The extent of ventilation defect assessed by (81m)Kr SPECT was higher than by (81m)Kr planar (slope of regression line 0.60, P<0.0001), likewise severity score (rank signed test: P<0.0001). Correlation between ventilation inhomogeneity and pulmonary function test (residual volume and T(L,CO)) in the COPD group revealed only significance for the SPECT acquisition. We found good reproducibility of visual assessment of ventilation defect extent (correlation: 0.97, P<0.0001) and severity (Kappa 0.62). In conclusion, visual scoring of extent and severity of ventilation defects was reproducible. Ventilation defects were better demonstrated with SPECT than planar imaging. The correlation to pulmonary function was better with SPECT than planar imaging.

Aged↗
PubMed2005

Cerebral infarction: incidence and risk factors after diagnostic and interventional cardiac catheterization--prospective evaluation at diffusion-weighted MR imaging.

PURPOSE: To prospectively evaluate incidence of clinically silent and clinically apparent embolic cerebral infarction following diagnostic and interventional coronary angiography and associated risk factors. MATERIALS AND METHODS: Written informed consent was obtained from all patients, and the study was approved by the research ethics committee of University of Heidelberg, Germany. Fifty-two patients, including 37 men (mean age, 66.1 years +/- 11.9 [standard deviation]) and 15 women (mean age, 65.3 years +/- 10.3), undergoing elective cardiac catheterization were examined 3-26 hours (mean, 15.3 hours +/- 6) before and 12-48 hours (mean, 25.9 hours +/- 10.4) after cardiac catheterization. Magnetic resonance imaging protocol included isotropic and anisotropic diffusion-weighted single-shot echo-planar sequences. T2-weighted turbo spin-echo and T1-weighted spin-echo sequences also were performed. Apparent diffusion coefficient maps were calculated to exclude false-positive reading results on diffusion-weighted images because of T2 shine-through effect. Images were assessed by two experienced radiologists blinded to clinical data. Cardiac catheterization was performed by 11 experienced cardiologists to exclude operator-related risk. A neurologic examination according to the National Institutes of Health Stroke Scale and Barthel index was performed by a senior cardiologist before acquisition of each image. Sixteen clinical and angiographic variables were analyzed with univariate analysis for ability to predict occurrence of cerebral infarction. RESULTS: No embolic cerebral lesions could be detected at diffusion-weighted imaging before catheterization. After coronary angiography, seven (15%) of 48 patients demonstrated nine focal cerebral infarcts affecting anterior and posterior circulation. Patients remained asymptomatic. Of all tested variables, only duration of the procedure was identified as an independent predictor of occurrence of cerebral infarction (P < .05). CONCLUSION: In this prospective study, asymptomatic cerebral infarction following cardiac catheterization occurred in 15% of patients in whom duration of the procedure was significantly longer than in those without infarction (P = .017).

Aged↗
PubMed1998

Escherichia coli genes expressed preferentially in an aquatic environment.

Enteric bacteria are frequently found in aquatic environments, where they may pose a risk to human health. Although bacterial survival and persistence in such habitats has been studied extensively, there is almost no information about bacterial adaptation to these conditions at the level of changes in gene expression. As a first exploration of this field, we have carried out a screen designed to identify Escherichia coli genes that show increased expression in an aquatic environment. The screen was performed by subtractive hybridization on a genomic library and led to the identification of several RNA species more abundant in cells inoculated in this medium than in stationary-phase cultures after growth in rich medium. The genes identified include specific tRNA operons and a gene of unknown function, gapC, with similarities to glyceraldehyde-3-phosphate dehydrogenases. E. coli K-12 strains appear to have accumulated mutations in gapC, which may impede its translation, whereas natural isolates have an intact gapC gene. Sequence comparison of gapC with related genes suggests its acquisition by horizontal gene transfer from gram-positive bacteria.

Bacterial Proteins↗
PubMed2002

The reproducibility of endometrial volume acquisition and measurement with the VOCAL-imaging program.

OBJECTIVES: To determine the intraobserver reproducibility of volume acquisition and repeatability of endometrial volume measurements using the VOCAL-imaging program (Virtual Organ Computer-aided AnaLysis). METHODS: Ten three-dimensional (3D) ultrasound datasets of the same endometrium were obtained from one patient during one scan session. For every 3D dataset, the endometrial volume was calculated by four different measurement techniques; three rotational methods and one conventional method. A single observer acquired each dataset and conducted all measurements. For the rotational technique, the manual mode was used to trace the myometrial-endometrial border through three different predefined rotations of 30 degrees, 15 degrees and 9 degrees . Endometrial volume was also measured in a conventional manner by scrolling through one of the multiplanar images and outlining the contour in another. Ten consecutive measurements were taken for each of the four measurement techniques so that 40 endometrial volume readings were obtained for each of the 10 3D-ultrasound datasets. RESULTS: Endometrial volume measurements were more reproducible with the rotational technique. Rotational methods employing a rotation step of less than 30 degrees were associated with coefficients of variation below 1% and intraclass correlation coefficients above 0.94. Within each of the 10 different scans, the homogeneity of the variance of measurements was significantly different according to the method of measurement (P = 0.022 to < 0.001). Post-hoc tests revealed that both the conventional and 30 degrees rotational methods resulted in a significantly smaller mean endometrial volume than both the 15 degrees and the 9 degrees rotational methods. CONCLUSIONS: Endometrial volume acquisition is reproducible and endometrial volume measurements are repeatable but they depend upon the technique of volume calculation in so much as rotational methods employing a rotation step of less than 30 degrees are associated with a significantly smaller variance in measurements and a significantly greater mean endometrial volume.

Adult↗
PubMed1994

Gated technetium-99m sestamibi for simultaneous assessment of stress myocardial perfusion, postexercise regional ventricular function and myocardial viability. Correlation with echocardiography and rest thallium-201 scintigraphy.

OBJECTIVES: This study compares technetium-99m sestamibi (sestamibi) electrocardiographic (ECG) gated single-photon emission computed tomography (gated SPECT) and echocardiography for the evaluation of myocardial function and assesses the feasibility of single-injection, single-acquisition stress perfusion/rest function technetium-99m sestamibi-gated SPECT as an alternative to conventional stress/rest imaging for assessment of myocardial perfusion and viability. BACKGROUND: Simultaneous assessment of stress perfusion and rest function is possible with gated SPECT acquisition of stress-injected technetium-99m sestamibi. METHODS: Rest thallium-201 SPECT followed by stress sestamibi-gated SPECT (acquired 0.5 to 1 h after sestamibi injection) was performed in 58 patients. Echocardiography was performed immediately after or before gated SPECT in 43 of the patients. All studies were analyzed by semiquantitative visual scoring. Sestamibi-gated SPECT studies were read for stress perfusion and rest wall motion and thickening. Reversibility on sestamibi-gated SPECT was defined as the presence of a definite stress defect with normal or mildly impaired wall motion or thickening on gated SPECT: RESULTS: There was high segmental score agreement between gated SPECT and echocardiography for wall motion (91%, kappa = 0.68, p < 0.001) and thickening (90%, kappa = 0.62, p < 0.001). Correlation for global wall motion (r = 0.98, p < 0.001) and thickening (r = 0.96, p < 0.001) scores between the two modalities was excellent. In 32 patients without previous myocardial infarction, there was excellent agreement for reversibility between stress sestamibi-gated SPECT and rest thallium-201/stress sestamibi (98%, kappa = 0.93, p < 0.01). However, in 26 patients with previous infarction, discordance between the two approaches was frequent, with 26% (20 of 78) of nonreversible defects by stress sestamibi-gated SPECT being reversible by rest thallium-201/stress sestamibi and 21% (23 of 112) of reversible defects by stress sestamibi-gated SPECT being nonreversible by rest thallium-201/stress sestamibi. CONCLUSIONS: Gated SPECT of stress-injected sestamibi correlates well with echocardiographic assessment of regional function and thus adds information to perfusion SPECT: In patients without previous myocardial infarction, a single-injection stress perfusion/rest function approach using sestamibi-gated SPECT can substitute for conventional stress/rest myocardial perfusion imaging, adding a rest perfusion study only if there are nonreversible defects or consideration of attenuation artifacts. In patients with previous myocardial infarction, the gated SPECT approach does not replace the need for a rest perfusion study.

Aged↗
PubMed2004

Resident training in advanced airway management.

Management of the difficult airway is an essential skill that should be taught during an anesthesiology residency. However, only a minority of anesthesiology residency programs have formal rotations in advanced airway management. We developed a formal advanced airway rotation as an integral part of our residency program, consisting of two 1-month rotations during the residency, each with a separate focus. While on the advanced airway rotation, the resident anesthesiologist is given a set of objectives, a list of required reading, and a required number of procedures unique to advanced airway management that they must perform during the rotation. We believe that this rotation has been beneficial in improving the residents' exposure to advanced airway techniques, and has dramatically improved their capabilities in this important aspect of anesthetic of anesthetic training. Additionally, the structure of the rotation ensures uniformity in the residents' acquisition of advanced airway skills.

Anesthesiology↗
PubMed1988

The muscle activity paradox during circular rhythmic leg movements.

A cyclist's legs make a simple 360 degrees circular and rhythmic movement, activated by a simple flexion-extension function in a sagittal plane. However, because of the simultaneous combination of leg rotation in the hip, knee and ankle joint with translation of the upper body, the general motion becomes quite complex. This complexity is increased by the anatomical interpretations of EMG readings taken during the pedalling cycle, indicating a high activity of 'flexor' muscles during the downward 'extension' of the leg (0-90 degrees propulsion phase of the pedalling cycle). This calls for an anatomical paradox. In order to verify these interpretations, the activity of six lower limb muscles was measured under field circumstances on nine elite cyclists using a portable EMG data acquisition system and active surface electrodes allowing remote (non-telemetric) monitoring of the cyclists' muscle activity patterns. Measurements were made during a 1000 m submaximal but constant effort and during a 200 m sprint. Confirmation of the anatomical paradox was found in both test circumstances. Analyses of the normalized EMG in combination with torque values of both hip and knee during the pedalling cycle indicate a zero torque at 135 degrees for the knee, while at this same angle the overall extensor activity ends in one leg and starts simultaneously in the other leg (at 315 degrees). Since the propulsion does not continue until 180 degrees, the flexor muscles have to be activated before the extension activity ends in order to generate the continuation of the circular motion until (and beyond) the bottom dead centre (180 degrees).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2005

Initial experience with balanced turbo field echo in depicting carotid artery stenosis: comparison with multiple overlapping thin slab acquisition and 3D contrast-enhanced magnetic resonance angiography.

PURPOSE: To compare balanced turbo field echo (bTFE) with multiple overlapping thin slice acquisition (MOTSA) and contrast-enhanced MR angiography (CE-MRA) in depicting carotid artery stenosis. MATERIALS AND METHODS: In this study 86 patients with cerebrovascular disease, who had been referred for a carotid examination, were imaged. All of the patients underwent MOTSA and one of four bTFE sequences followed by CE-MRA. Formatted maximum intensity projections (MIPs) and source images were read in a blinded fashion by a radiologist. Inter- and intrasequence statistical analyses were performed. RESULTS: We first compared image quality (IQ) and fat, background, and venous suppression using four distinct bTFE protocols in 118 carotid arteries, and found that bTFE4 performed the best. We then compared IQ, grades of stenosis, and background and venous suppression among bTFE4, MOTSA, and CE-MRA. bTFE produced significantly better IQ and venous suppression (P < 0.001), and higher SNR and CNR (P < 0.05) when compared to MOTSA. CONCLUSION: The bTFE sequence is robust and provides high-quality images in patients with mild to moderate carotid artery stenosis. Even though there is a tendency to overestimate stenosis with bTFE compared to CE-MRA, the shorter scan time of bTFE coupled with enhanced SNR and CNR measurements validates it as a clinically useful adjunct to MOTSA, if not a replacement.

Aged↗
PubMed1998

Transposition of RhoA to the murine Y chromosome.

In an effort to produce a more complete transcription map of the short (approximately 5 Mb) arm of the mouse Y chromosome, we have initiated exon trapping from Yp-derived YACs. Sequence analysis of the trapped products has identified exons of previously cloned mouse Y-located genes Zfy and SSty and potential exons homologous to the human Y-located Tspy gene family. In addition, a family of three Yp-located transcripts that show close homology to human RHOA (locus designation ARHA), a member of the Ras family of small GTPases, has been identified. To determine whether these Yp sequences had been transposed from an autosomal ancestor, we used this trapped product to isolate a full-length autosomal mouse RhoA cDNA that is 80% identical at the nucleotide level and 98% identical at the amino acid level to human RHOA and maps to mouse Chromosome 2 (locus designation ArhA). Sequence analysis indicates that the Y-linked copies have diverged from the autosomal form, with small deletions precluding maintenance of a significant open reading frame in all Yp copies. Yet RT-PCR analysis indicates that two of these pseudogenes, RhoAy1 and 3, are expressed in a testis-specific manner, in sharp contrast to the nearly ubiquitous expression pattern of the autosomal ancestor. The data indicate that the Y copies of RhoA have been transposed from an autosome, followed by subsequent duplication, sequence divergence, and acquisition of a testis-specific promoter/enhancer.

Animals↗
PubMed1990

Acquisition and retention of a letter-detection skill.

In two experiments, we examined the acquisition and retention of a letter-detection skill with a consistent-mapping procedure. In Experiment 1, subjects were trained from 0 to 4 sessions at detecting the letter H in displays containing random letters, and retesting occurred after a 1-month delay. Performance improved and in some cases became more automatic, and the performance level was maintained over the retention interval. When tested with a prose passage, the high error rate on the word THE was eliminated after training and after the retention interval, regardless of the amount of training. In Experiment 2, two subjects were given 12 sessions of training followed by a retention test 6 months later. For 1 subject there was also a retention test 15 months after acquisition. Performance improved dramatically with training, and substantial but not complete automaticity was achieved. Performance on the retention tests was close to the final acquisition level. The surprising lack of forgetting in this study was contrasted with the substantial forgetting typically found in studies of verbal learning.

Form Perception↗
PubMed2003

Analysis of genome plasticity in pathogenic and commensal Escherichia coli isolates by use of DNA arrays.

Genomes of prokaryotes differ significantly in size and DNA composition. Escherichia coli is considered a model organism to analyze the processes involved in bacterial genome evolution, as the species comprises numerous pathogenic and commensal variants. Pathogenic and nonpathogenic E. coli strains differ in the presence and absence of additional DNA elements contributing to specific virulence traits and also in the presence and absence of additional genetic information. To analyze the genetic diversity of pathogenic and commensal E. coli isolates, a whole-genome approach was applied. Using DNA arrays, the presence of all translatable open reading frames (ORFs) of nonpathogenic E. coli K-12 strain MG1655 was investigated in 26 E. coli isolates, including various extraintestinal and intestinal pathogenic E. coli isolates, 3 pathogenicity island deletion mutants, and commensal and laboratory strains. Additionally, the presence of virulence-associated genes of E. coli was determined using a DNA "pathoarray" developed in our laboratory. The frequency and distributional pattern of genomic variations vary widely in different E. coli strains. Up to 10% of the E. coli K-12-specific ORFs were not detectable in the genomes of the different strains. DNA sequences described for extraintestinal or intestinal pathogenic E. coli are more frequently detectable in isolates of the same origin than in other pathotypes. Several genes coding for virulence or fitness factors are also present in commensal E. coli isolates. Based on these results, the conserved E. coli core genome is estimated to consist of at least 3,100 translatable ORFs. The absence of K-12-specific ORFs was detectable in all chromosomal regions. These data demonstrate the great genome heterogeneity and genetic diversity among E. coli strains and underline the fact that both the acquisition and deletion of DNA elements are important processes involved in the evolution of prokaryotes.

Electrophoresis, Gel, Pulsed-Field↗
PubMed2002

Comparing light sensitivity, linearity and step response of electronic cameras for ophthalmology.

PURPOSE: To develop and test a procedure to measure and compare light sensitivity, linearity and step response of electronic cameras. METHODS: The pixel value (PV) of digitized images as a function of light intensity (I) was measured. The sensitivity was calculated from the slope of the P(I) function, the linearity was estimated from the correlation coefficient of this function. To measure the step response, a short sequence of images was acquired. During acquisition, a light source was switched on and off using a fast shutter. The resulting PV was calculated for each video field of the sequence. RESULTS: A CCD camera optimized for the near-infrared (IR) spectrum showed the highest sensitivity for both, visible and IR light. There are little differences in linearity. The step response depends on the procedure of integration and read out.

Equipment Design↗
PubMed2004

Transcriptome of uropathogenic Escherichia coli during urinary tract infection.

A uropathogenic Escherichia coli strain CFT073-specific DNA microarray that includes each open reading frame was used to analyze the transcriptome of CFT073 bacteria isolated directly from the urine of infected CBA/J mice. The in vivo expression profiles were compared to that of E. coli CFT073 grown statically to exponential phase in rich medium, revealing the strategies this pathogen uses in vivo for colonization, growth, and survival in the urinary tract environment. The most highly expressed genes overall in vivo encoded translational machinery, indicating that the bacteria were in a rapid growth state despite specific nutrient limitations. Expression of type 1 fimbriae, a virulence factor involved in adherence, was highly upregulated in vivo. Five iron acquisition systems were all highly upregulated during urinary tract infection, as were genes responsible for capsular polysaccharide and lipopolysaccharide synthesis, drug resistance, and microcin secretion. Surprisingly, other fimbrial genes, such as pap and foc/sfa, and genes involved in motility and chemotaxis were downregulated in vivo. E. coli CFT073 grown in human urine resulted in the upregulation of iron acquisition, capsule, and microcin secretion genes, thus partially mimicking growth in vivo. On the basis of gene expression levels, the urinary tract appears to be nitrogen and iron limiting, of high osmolarity, and of moderate oxygenation. This study represents the first assessment of any E. coli pathotype's transcriptome in vivo and provides specific insights into the mechanisms necessary for urinary tract pathogenesis.

Animals↗
PubMed1998

Identification of iron-regulated proteins of Mycobacterium tuberculosis and cloning of tandem genes encoding a low iron-induced protein and a metal transporting ATPase with similarities to two-component metal transport systems.

Iron plays a central role in the pathogenesis of Mycobacterium tuberculosis, the principal causative agent of tuberculosis. To learn more about iron acquisition by this bacterium, its iron regulated proteins (IRPs) were investigated. Seven IRPs were identified - three increased by high iron concentrations, and four by low iron concentrations. The smallest protein induced by low iron, Irp10, is tightly iron regulated as it is virtually absent in bacteria cultured in the presence of high iron concentrations. The gene (irpA ) encoding this protein and an adjacent open reading frame, mtaA, were cloned and sequenced. The protein encoded by mtaA (Mta72) has striking homology to metal transporting P-type ATPases. This study suggests that Irp10 and Mta72 function as a two-component metal transport system in M. tuberculosis.

ATP-Binding Cassette Transporters↗
PubMedDate not supplied

Hepatic MR imaging: comparison of RARE derived sequences with conventional sequences for detection and characterization of focal liver lesions.

BACKGROUND: We compared two T2-weighted turbo spin echo (TSE) sequences with a T2-weighted conventional SE (CSE) sequence to determine whether sequences derived from rapid acquisition with relaxation enhancement such as TSE could replace CSE for the detection and subsequent characterization of focal liver lesions. METHODS: A total of 55 consecutive patients with 107 liver lesions underwent magnetic resonance imaging examinations at 1.5 Tesla, with a constant imaging protocol. TSE pulse sequences were acquired with eight echo trains (repetition time [TR], 4718 ms; echo time [TE], 90 ms; acquisition time [TA], 4.03 min; and a symmetric k-space ordering scheme) and 11 echo trains (TR, 4200 ms; TE, 140 ms; TA, 4.40 min; and an asymmetric k-space ordering scheme) and compared with CSE (TR, 2300 ms; TE, 45/90 ms; TA, 9.53 min). Images were analyzed qualitatively by scoring image quality and artifacts and counting focal liver lesions by independent reading with consensus obtained for discrepancies. Quantitative analysis was performed by measuring signal-to-noise (S/N), contrast-to-noise (C/N), and tumor-liver signal intensity (T/L) ratios. RESULTS: T2-weighted TSE sequences provided better subjective image quality and reduced artifacts as compared with the T2-weighted CSE sequence. CSE and TSE sequences exhibited no statistically significant differences in liver S/N, lesion-liver C/N (CSE TE, 90 ms: 18.6 +/- 14.0; TSE TE, 90 ms: 16.5 +/- 12.9) and the detectability of focal liver lesions. Heavily T2-weighted TSE with a TE of 140 ms allowed correct characterization of focal liver lesions based on a T/L ratio of 3.0 in 84% of patients. CONCLUSIONS: T2-weighted TSE sequences are as suited as CSE for the detection (TE, 90 ms), and appear to be superior for the characterization (TE, 140 ms), of focal hepatic lesions. Whether a single sequence, such as a double-echo TSE or a single-echo TSE sequence with a TE between 110 and 120 ms, might perform both functions as well or better than CSE is unknown. However, because of time savings, TSE eventually may be preferred over CSE.

Artifacts↗
PubMed1994

Language and communication in autistic disorders.

Communication problems form one of the key diagnostic criteria for autism, but there is a wide variety of manifestations. The theory that autistic individuals are unable to represent mental states can shed light on both the nature and range of communication impairments. This theory predicts that the specific communication deficit lies in the use of language to affect other minds. Language is not special in this respect, and is important only in so far as it may be used to give evidence of a speaker's thoughts and intentions. Thus, in autism, language level would be expected to relate strongly to performance on standard tests of theory of mind. Normal language acquisition appears to build upon the ability to recognize and orient towards ostensive behaviour. For this reason, it may not be necessary to postulate additional language impairments in order to explain the almost universal prevalence of language delay in children with autism. Autism, then, provides a model for studying the important distinction between language and communication, and demonstrates the vital part which mind-reading plays in normal human verbal and non-verbal interaction.

Autistic Disorder↗
PubMed2006

Probabilistic models of language processing and acquisition.

Probabilistic methods are providing new explanatory approaches to fundamental cognitive science questions of how humans structure, process and acquire language. This review examines probabilistic models defined over traditional symbolic structures. Language comprehension and production involve probabilistic inference in such models; and acquisition involves choosing the best model, given innate constraints and linguistic and other input. Probabilistic models can account for the learning and processing of language, while maintaining the sophistication of symbolic models. A recent burgeoning of theoretical developments and online corpus creation has enabled large models to be tested, revealing probabilistic constraints in processing, undermining acquisition arguments based on a perceived poverty of the stimulus, and suggesting fruitful links with probabilistic theories of categorization and ambiguity resolution in perception.

Brain↗
PubMed2004

Are nonlinguistic functions in "Broca's area" prerequisites for language acquisition? FMRI findings from an ontogenetic viewpoint.

There is incomplete consensus on the anatomical demarcation of Broca's area in the left inferior frontal gyrus and its functional characterization remains a matter of debate. Exclusive syntactic specialization has been proposed, but is overall inconsistent with the neuroimaging literature. We examined three functional MRI (fMRI) datasets on lexicosemantic decision, tone discrimination, and visuomotor coordination for potential overlap of activation. A single site of convergent activation across all three paradigms was found in the left inferior frontal lobe (area 44/45). This result is discussed in the context of animal and human studies showing inferior frontal participation in visuomotor and audiomotor functions as well as working memory. We propose that Broca's area involvement in lexical semantics and syntax emerges from these nonlinguistic functions, which are prerequisites for language acquisition.

Adult↗