Impact of clinical history on fracture detection with radiography

The effect of knowledge of localizing symptoms and signs in the detection of fractures was studied. Forty radiographs of the extremities were examined twice by seven radiologists; the sessions were separated by 4 months. In 26 cases, a subtle fracture was present; 14 cases were normal. In half of the cases at each session, the precise location of pain, tenderness, or swelling was provided. The observer was asked to determine if the case was normal or abnormal (provide the exact location of the fracture) and to indicate the degree of confidence in the diagnosis. Responses were converted to a numeric scale for analysis. Analysis of receiver operator characteristic parameters indicates that clues regarding location of trauma facilitate detection of fractures. The improvement is based largely on an increased true-positive rate without an increased false-positive rate, regardless of the decision criteria of the radiologist (overall willingness to "overread" or "underread"). This has direct clinical applicability and reinforces the plea of radiologists for precise clinical information.     

Photoelectric recording of mechanical responses of cardiac myocytes

A method to monitor contraction of isolated myocytes by transmicroscopic photometry is illustrated. Two photodiodes are mounted inside an inverse microscope used for visual control of a cell. Illumination of one diode varies in proportion to changes in cell length. The contraction signal is amplified in a comparator circuit. Spatial resolution of the device is in the order of 1 m which corresponds to about 5% of cell shortening in the fully activated state of contraction. The method was tested on isolated myocytes from guinea-pig ventricle. Optical records of contraction in response to action potentials or during voltage clamp compare well with the contractile behaviour of multicellular preparations.     

The application of co-culture in assisted reproduction: 10 years of experience with human embryos

Co-culture techniques using fetal bovine uterine fibroblasts or bovine oviductal epithelial cells have improved embryonic development prior to replacement in humans. In initial co-culture trials, embryo development and implantation rates increased after just 1 day in culture. The most overt characteristics noted following co-culture were improved blastomere development and characteristics, reduced fragmentation, and the appearance of swollen blastomeres. In addition, an increase in the incidence of zona thickness variation was detected. Improved development of polyspermic and supernumerary embryos to the blastocyst stage was noted in initial trials. Retrospective analysis indicated that certain patient subgroups benefit the most from co-culture. As a result, co-culture is now applied routinely to patients that have previously failed attempts at in-vitro fertilization (IVF) and/or have endocrine imbalances such as polycystic ovarian syndrome and elevated day 3 concentrations of follicle stimulating hormone (FSH). The use of co-culture prior to or following cryopreservation has also proven to be beneficial to human embryos. The proposed beneficial mechanisms thought to improve embryonic development include a secretory and/or a scavenging role. Evidence describing the postulated benefits is discussed.     

A survey of different high resolution visualization modes of a volumetric object with applications

Summary In view of the variety of 3D representation techniques, a clinical study was carried out in order to evaluate their respective usefulness. It appears that a single technique cannot be claimed to be valid for all clinical situations and that a combination of representations brings more relevant information. Among the different techniques a clear delineation must be established between those which allow the accurate definition of landmarks (multiplanar reformation, surface representation), and those which do not (integral shading, reconstructed radiology). The main point is the possibility to recognize anatomical landmarks on these latter modes and to choose oblique cut planes in relation to them. Visualization quality is strongly dependent upon the acquisition protocol which must provide a spatial resolution as isotropic as possible.

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Une revue de différents modes de visualisation en haute résolution d'un objet volumique avec des applications

Résumé Face à la variété des techniques de représentation 3D une étude clinique a été conduite pour évaluer leurs utilités respectives. Il apparait qu'une technique unique ne peut pas convenir à toutes les situations cliniques et qu'une combinaison de différents modes de présentation apporte une information plus pertinente. Parmi les différentes techniques une distinction claire doit être établie entre celles qui autorisent la prise de repères précis (reformatage multiplanaire, représentation de surface), et celles qui ne le permettent pas (ombrage intégral, radiologie reconstruite). Le point principal est la possibilité de reconnaître des repères anatomiques sur ces derniers modes et de choisir des plans de coupe en relation avec eux. La qualité de la visualisation dépend étroitement du protocole d'acquisition qui doit fournir une résolution aussi isotrope que possible.

     

Intergenerational instability of the CAG repeat of the gene for Machado- Joseph disease (MJD1) is affected by the genotype of the normal chromosome: implications for the molecular mechanisms of the instability of the CAG repeat

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder caused by unstable expansion of a CAG repeat in the MJD1 gene at 14q32.1. To identify elements affecting the intergenerational instability of the CAG repeat, we investigated whether the CGG/GGG polymorphism at the 3' end of the CAG repeat affects intergenerational instability of the CAG repeat. The [expanded (CAG)n-CGG]/[normal (CAG)n- GGG] haplotypes were found to result in significantly greater instability of the CAG repeat compared to the [expanded (CAG)n- CGG]/[normal (CAG)n-CGG] or [expanded (CAG)nGGG]/[normal (CAG)n-GGG] haplotypes. Multiple stepwise logistic regression analysis revealed that the relative risk for a large intergenerational change in the number of CAG repeat units (< -2 or > 2) is 7.7-fold (95% CI: 2.5-23.9) higher in the case of paternal transmission than in that of maternal transmission and 7.4-fold (95% CI: 2.4-23.3) higher in the case of transmission from a parent with the [expanded (CAG)n-CGG]/[normal (CAG)n-GGG] haplotypes than in that of transmission from a parent with the [expanded (CAG)n-CGG]/[normal (CAG)n-CGG] or [expanded (CAG)n- GGG]/[normal (CAG)n-GGG] haplotypes. The combination of paternal transmission and the [expanded (CAG)n-CGG]/[normal (CAG)n-GGG] haplotypes resulted in a 75.2-fold (95% CI: 9.0-625.0) increase in the relative risk compared with that of maternal transmission and the [expanded (CAG)n-CGG]/[normal (CAG)n-CGG] or [expanded (CAG)n- GGG]/[normal (CAG)n-GGG] haplotypes. The results suggest that an inter- allelic interaction is involved in the intergenerational instability of the expanded CAG repeat.      

Functional consequences of ROMK mutants linked to antenatal Bartter's syndrome and implications for treatment

The antenatal variant of Bartter's syndrome is an autosomal recessive kidney disease characterized by polyhydramnios, premature delivery, hypokalemic alkalosis and hypercalciuria. It is genetically heterogeneous, having been linked recently to mutations in an ATP- sensitive, renal outer medullary K+channel, ROMK, and earlier to mutations in the Na-K-2Cl co-transporter, NKCC2. We characterized four of the mutations reported in three heterozygous ROMK variants of antenatal Bartter's and found that each expressed a distinct phenotype in Sf9 cells. One mutation expressed normal function and appears to be an allelic polymorphism. The other three mutations produced channels with significantly reduced K+fluxes. However, the mechanisms in each case were different and reflected abnormalities in phosphorylation, proteolytic processing or protein trafficking. The different mechanisms may be important in the design of appropriate therapy for patients with this disease.