Cardiac diffusion-weighted and tensor imaging: a Society for Cardiovascular Magnetic Resonance (SCMR) special interest group consensus statement.

Thanks to recent developments in Cardiovascular magnetic resonance (CMR), cardiac diffusion-weighted magnetic resonance is fast emerging in a range of clinical applications. Cardiac diffusion-weighted imaging (cDWI) and diffusion tensor imaging (cDTI) now enable investigators and clinicians to assess and quantify the 3D microstructure of the heart. Free-contrast DWI is uniquely sensitized to the presence and displacement of water molecules within the myocardial tissue, including the intra-cellular, extra-cellular and intra-vascular spaces. CMR can determine changes in microstructure by quantifying: a) mean diffusivity (MD) -measuring the magnitude of diffusion; b) fractional anisotropy (FA) - specifying the directionality of diffusion; c) helix angle (HA) and transverse angle (TA) -indicating the orientation of the cardiomyocytes; d) E2A and E2A mobility - measuring the alignment and systolic-diastolic mobility of the sheetlets, respectively. This document provides recommendations for both clinical and research cDWI and cDTI, based on published evidence when available and expert consensus when not. It introduces the cardiac microstructure focusing on the cardiomyocytes and their role in cardiac physiology and pathophysiology. It highlights methods, observations and recommendations in terminology, acquisition schemes, post-processing pipelines, data analysis and interpretation of the different biomarkers. Despite the ongoing challenges discussed in the document and the need for ongoing technical improvements, it is clear that cDTI is indeed feasible, can be accurately and reproducibly performed and, most importantly, can provide unique insights into myocardial pathophysiology.

Relationship between cardiac diffusion tensor imaging parameters and anthropometrics in healthy volunteers.

BACKGROUND: In vivo cardiac diffusion tensor imaging (cDTI) is uniquely capable of interrogating laminar myocardial dynamics non-invasively. A comprehensive dataset of quantative parameters and comparison with subject anthropometrics is required. METHODS: cDTI was performed at 3T with a diffusion weighted STEAM sequence. Data was acquired from the mid left ventricle in 43 subjects during the systolic and diastolic pauses. Global and regional values were determined for fractional anisotropy (FA), mean diffusivity (MD), helix angle gradient (HAg, degrees/%depth) and the secondary eigenvector angulation (E2A). Regression analysis was performed between global values and subject anthropometrics. RESULTS: All cDTI parameters displayed regional heterogeneity. The RR interval had a significant, but clinically small effect on systolic values for FA, HAg and E2A. Male sex and increasing left ventricular end diastolic volume were associated with increased systolic HAg. Diastolic HAg and systolic E2A were both directly related to left ventricular mass and body surface area. There was an inverse relationship between E2A mobility and both age and ejection fraction. CONCLUSIONS: Future interpretations of quantitative cDTI data should take into account anthropometric variations observed with patient age, body surface area and left ventricular measurements. Further work determining the impact of technical factors such as strain and SNR is required.

Syrian Hamster Embryo (SHE) cell transformation assay with and without X-ray irradiation of feeder cells using Di(2-ethylhexyl)phthalate (DEHP) and N-nitroso-N-methylnitroguanidine (MNNG).

The SHE cell transformation assay has traditionally been conducted with a feeder layer of X-ray irradiated cells to provide growth support to the target cells seeded in low numbers. The need for an X-ray irradiated feeder cell layer necessitates the maintenance of an X-ray machine and the additional step to seed feeder cells prior to plating target cells. This laboratory has previously reported a method allowing target cells to be seeded in conditioned media prepared from the stock culture flasks in lieu of plating them on a feeder layer (Pant et al. [1,2,4]). In order to expand the data base for chemicals tested using this method, we describe in this paper the results obtained testing Di(2-ethylhexyl)phthalate (DEHP) and N-nitroso-N-methylnitroguanidine (MNNG) which are known to give positive responses in the standard SHE cell transformation assay. With freshly prepared conditioned medium (used within 2 weeks of preparation), there was essentially no difference in the number of target cell colonies in the conditioned medium and in the plates with the X-ray irradiated feeder cell layer. The plating efficiencies of the vehicle controls were within the historical range for the standard SHE cell transformation assay. In more than ten experiments the positive control benzo(a)pyrene [B(a)P] elicited a significant increase in morphological transformation frequency (MTF), with or without X-ray irradiated feeder cells. Compounds, DEHP and MNNG, were tested in the SHE cell transformation assay with and without an X-ray irradiated feeder layer and using a 7-day exposure regimen. The results were comparable between experiments performed using either method. These results demonstrate the feasibility of conducting the SHE cell transformation assay without the use of an X-ray irradiated feeder layer, thereby simplifying the test procedure and assisting the scoring of morphologically transformed colonies.

The Medicago Genome Initiative: a model legume database.

The Medicago Genome Initiative (MGI) is a database of EST sequences of the model legume MEDICAGO: truncatula. The database is available to the public and has resulted from a collaborative research effort between the Samuel Roberts Noble Foundation and the National Center for Genome Resources to investigate the genome of M.truncatula. MGI is part of the greater integrated MEDICAGO: functional genomics program at the Noble Foundation (http://www.noble.org ), which is taking a global approach in studying the genetic and biochemical events associated with the growth, development and environmental interactions of this model legume. Our approach will include: large-scale EST sequencing, gene expression profiling, the generation of M.truncatula activation-tagged and promoter trap insertion mutants, high-throughput metabolic profiling, and proteome studies. These multidisciplinary information pools will be interfaced with one another to provide scientists with an integrated, holistic set of tools to address fundamental questions pertaining to legume biology. The public interface to the MGI database can be accessed at http://www.ncgr.org/research/mgi.

Influence of soluble suture factors on in vitro macrophage function.

Suture materials may interact with immune competent cells and thereby affect localized immunity. Macrophages are central to the inflammatory response and coordinate wound healing. They are also involved in the clearance of foreign material, bacteria and malignant cells. We studied the influence of soluble factors associated with silk, steel, nylon, polyglactin, polydioxanone and chromic catgut sutures on macrophage adherence, phagocytosis and the production of lysozyme and tumour necrosis factor. Soluble factors from suture materials influenced macrophage behaviour in vitro causing cellular activation, functional impairment and alterations in secreted levels of the cytokine tumour necrosis factor and the bactericidal agent lysozyme. Of the six materials studied, polyglactin had the most extreme effect, causing significant inhibition of cell adherence and lysozyme production. Silk also exerted a considerable effect on macrophages, significantly inhibiting adherence. In contrast, steel and polydioxanone media caused minimal inhibition of macrophage function although, as with all materials, they did activate the cells. This study has demonstrated that sutures release immunotoxic factors which considerably influence macrophage behaviour in vitro. These effects may have important clinical implications.

Medical causes of faecal incontinence.

Faecal incontinence can result from a disturbance in any one of the multiple factors which maintain continence. In practice, faecal incontinence is most commonly seen in women who have had children. This symptom can also be seen in other patient groups, who may in addition have had children, and this article will discuss the mechanisms involved in the loss of continence in diabetics and patients with multiple sclerosis.

Nasal intermittent positive-pressure ventilation in weaning intubated patients with chronic respiratory disease from assisted intermittent, positive-pressure ventilation.

Nasal intermittent positive-pressure ventilation (NIPPV) has been used for domiciliary ventilatory support, and to avoid intubation for acute respiratory failure in patients with chronic airflow limitation (CAL). Its role in weaning patients from assisted ventilation in intensive care has not been defined. We have used NIPPV to wean 14 patients with respiratory disease who were referred either because of predicted difficulty in weaning or failure to wean using standard techniques. Twelve patients were ventilated for acute respiratory failure; eight patients had CAL and four had chest wall or neuromuscular disease. Two further patients with chest disease were difficult to wean following surgery. Weaning was successful in 13 patients. NIPPV corrected hypoxia, reduced hypercapnia and was well tolerated. Weaning from NIPPV was achieved in all patients with CAL, although three patients with chest wall disease later required domiciliary ventilatory support. All but one of the patients survived to leave hospital. NIPPV may have an important role in weaning from assisted ventilation, particularly in patients with underlying chronic respiratory disease. This preliminary report needs to be followed by a controlled study comparing NIPPV with established weaning methods.

The Saccharomyces cerevisiae RAD7 and RAD16 genes are required for inducible excision of endonuclease III sensitive-sites, yet are not needed for the repair of these lesions following a single UV dose.

The RAD7 and RAD16 genes of Saccharomyces cerevisiae have roles in the repair of UV induced CPDs in nontranscribed genes [1], and in the repair of CPDs in the nontranscribed strand of transcribed genes [2]. Previously, we identified an inducible component to nucleotide excision repair (NER), which is absent in a rad16 delta strain [3]. We have examined the repair of UV induced endonuclease III sensitive-sites (EIIISS), and have shown repair of these lesions to proceed by NER but their removal from nontranscribed regions is independent of RAD7 and RAD16. Furthermore, EIIISS are repaired with equal efficiency from both transcribed and nontranscribed genes [4]. In order to dissect the roles of RAD7 and RAD16 in the above processes we examined the repair of EIIISS in the MAT alpha and HML alpha loci, which are, respectively, transcriptionally active and inactive in alpha haploid cells. These loci have elevated levels of these lesions after UV (in genomic DNA EIIISS constitute about 10% of total lesions, whereas CPDs are about 70% of total lesions). We have shown that excision of UV induced EIIISS is enhanced following a prior UV irradiation. No enhancement of repair was detected in either the rad7 delta or the rad16 delta mutant. The fact that RAD7 and RAD16 are not required for the repair of EIIISS per se yet are required for the enhanced excision of these lesions from MAT alpha and HML alpha suggests two possibilities. These genes have two roles in NER, namely in the repair of CPDs from nontranscribed sequences, and in enhancing NER itself regardless of whether these genes' products are required for the excision of the specific lesion being repaired. In the latter case, the induction of RAD7 and RAD16 may increase the turnover of complexes stalled in nontranscribed DNA so as to increase the availability of NER proteins for the repair of CPDs and EIIISS in all regions of the genome.

Construction and evaluation of a potassium-selective tube-mounted membrane electrode.

A simple procedure for the rapid construction of inexpensive potassium-selective electrodes with valinomycin-based PVC membranes is described. Potassium-selective membranes were formed on the end of Parafilm- or Tygon-covered glass tubes by dipping the tubes into a mixture of PVC, valinomycin, and dioctyl sebacate dissolved in tetrahydrofuran. Small internal Ag/AgCl reference electrodes were made with silver wire and placed inside the tubes with AgCl-saturated potassium chloride solution. This procedure yields tube-mounted membrane electrodes that perform as well as commercially available potassium-selective electrodes in terms of their response characteristics and practical applications with soil extracts. Moreover, it facilitates the evaluation of membranes with different compositions, for making ion-selective electrodes.

Laparoscopic laser cholecystectomy: results of the technique in 210 patients.

The results of laparoscopic laser cholecystectomy (LLC) in a consecutive series of 210 patients, operated on between May 1990 and August 1991, were assessed to analyse the advantages of the technique and to detail the causes of any technical problems, failures, or complications. The operations were performed by JMcKW and ADNS. A success rate of 98% (206/210) was achieved with a minor complication rate of 13% (26/210) and major complication rate of 3% (7/206), including three patients (3/206; 1.5%) who had a reactionary haemorrhage postoperatively, two requiring laparotomy. The length of hospital stay was 48 h or less in over 80% (148/184) of the patients. The period of absence from work was 2 weeks or less in over 90% (118/130) of the patients. Cholecystectomy can safely be performed laparoscopically and this procedure has significant advantages over open cholecystectomy.

How to build a cardiac surgery program.

Follow one hospital's experience in opening a new heart center, including its philosophy, triaging of issues, and staff preparation to achieve successful patient outcomes.

Genotoxicity testing of a Hoodia gordonii extract.

Hoodia gordonii extract consists of a mixture of steroid glycosides, fatty acids, plant sterols and alcohols. As part of the overall safety assessment H. gordonii extract was assessed for genotoxicity in two assays in vitro: a bacterial mutation assay; and a gene mutation assay using mouse lymphoma cells. H. gordonii extract showed no evidence of genotoxic activity in either of these assays. In addition, H. gordonii extract was assessed for mutagenic activity in a bone marrow micronucleus (MN) assay in the mouse, with 400mg/kg selected as the high-dose group, based on observations in a dose-range-finding study. The group mean frequencies of micronucleated polychromatic erythrocytes of treated animals were similar to those of the vehicle control group, indicating H. gordonii extract to be non-genotoxic under the conditions of this test. All assays were performed in compliance with the Good Laboratory Practice Regulations and in accordance with standard guidelines for genotoxicity tests. H. gordonii extract was shown to be non-genotoxic in 3 independent assays (a bacterial mutation test, a gene mutation assay using mouse lymphoma cells and a bone marrow micronucleus assay in the mouse).

Towards clinical assessment of velopharyngeal closure using MRI: evaluation of real-time MRI sequences at 1.5 and 3 T.

OBJECTIVE: The objective of this study was to demonstrate soft palate MRI at 1.5 and 3 T with high temporal resolution on clinical scanners. METHODS: Six volunteers were imaged while speaking, using both four real-time steady-state free-precession (SSFP) sequences at 3 T and four balanced SSFP (bSSFP) at 1.5 T. Temporal resolution was 9-20 frames s(-1) (fps), spatial resolution 1.6 × 1.6 × 10.0-2.7 × 2.7 × 10.0 mm(3). Simultaneous audio was recorded. Signal-to-noise ratio (SNR), palate thickness and image quality score (1-4, non-diagnostic-excellent) were evaluated. RESULTS: SNR was higher at 3 T than 1.5 T in the relaxed palate (nasal breathing position) and reduced in the elevated palate at 3 T, but not 1.5 T. Image quality was not significantly different between field strengths or sequences (p=NS). At 3 T, 40% acquisitions scored 2 and 56% scored 3. Most 1.5 T acquisitions scored 1 (19%) or 4 (46%). Image quality was more dependent on subject or field than sequence. SNR in static images was highest with 1.9 × 1.9 × 10.0 mm(3) resolution (10 fps) and measured palate thickness was similar (p=NS) to that at the highest resolution (1.6 × 1.6 × 10.0 mm(3)). SNR in intensity-time plots through the soft palate was highest with 2.7 × 2.7 × 10.0 mm(3) resolution (20 fps). CONCLUSIONS: At 3 T, SSFP images are of a reliable quality, but 1.5 T bSSFP images are often better. For geometric measurements, temporal should be traded for spatial resolution (1.9 × 1.9 × 10.0 mm(3), 10 fps). For assessment of motion, temporal should be prioritised over spatial resolution (2.7 × 2.7 × 10.0 mm(3), 20 fps). Advances in knowledge Diagnostic quality real-time soft palate MRI is possible using clinical scanners and optimised protocols have been developed. 3 T SSFP imaging is reliable, but 1.5 T bSSFP often produces better images.

In vitro and in vivo repeatability of abdominal diffusion-weighted MRI.

OBJECTIVE: To study the in vitro and in vivo (abdomen) variability of apparent diffusion coefficient (ADC) measurements at 1.5 T using a free-breathing multislice diffusion-weighted (DW) MRI sequence. METHODS: DW MRI images were obtained using a multislice spin-echo echo-planar imaging sequence with b-values=0, 100, 200, 500, 750 and 1000 s mm(-2). A flood-field phantom was imaged at regular intervals over 100 days, and 10 times on the same day on 2 occasions. 10 healthy volunteers were imaged on two separate occasions. Mono-exponential ADC maps were fitted excluding b=0. Paired analysis was carried out on the liver, spleen, kidney and gallbladder using multiple regions of interest (ROIs) and volumes of interest (VOIs). RESULTS: The in vitro coefficient of variation was 1.3% over 100 days, and 0.5% and 1.0% for both the daily experiments. In vivo, there was no statistical difference in the group mean ADC value between visits for any organ. Using ROIs, the coefficient of reproducibility was 20.0% for the kidney, 21.0% for the gallbladder, 24.7% for the liver and 28.0% for the spleen. For VOIs, values fall to 7.7%, 6.4%, 8.6% and 9.6%, respectively. CONCLUSION: Good in vitro repeatability of ADC measurements provided a sound basis for in vivo measurement. In vivo variability is higher and when considering single measurements in the abdomen as a whole, only changes in ADC value greater than 23.1% would be statistically significant using a two-dimensional ROI. This value is substantially lower (7.9%) if large three-dimensional VOIs are considered.