Hand and wrist imaging using a low-field dedicated MRI system

Summary Purpose of this study was to evaluate the diagnostic value of a low field dedicated MRI system in hand and wrist imaging. All 308 exams of the hand and wrist, that were performed on a low-field dedicated MRI system (Artoscan, Esaote Biomedica, Italy) in our institution in 1996, and high-field MRI exams performed in addition as part of the diagnostic work-up, were evaluated and correlated to final operative (n = 64) and histologic (n = 12) reports. 90 % of all low-field MRI scans stated a diagnosis according to clinical suspicion. In 62 % the clinical question was answered, and in 26 % additional pathologies were identified. An MR-diagnosis completely different from the clinical suspicion was stated in 2 %. High field exams contributed additional information in 6 of 36 patients. In 3 patients a tumor was not shown completely in the limited field-of-view of the dedicated low-field MRI-system. Frequency-selective fat-suppression pulse sequences and a better spatial resolution were the reasons for the additional information obtained in the other three patients. Low-field dedicated MR-imaging is a valuable method in the extensive work-up of the hand and wrist. Osseous, ligamentous and tendinous pathologies are well depicted. Large or infiltrative tumors should be referred to a high-field system.      

Whole-body imaging of sequestration of Plasmodium falciparum in the rat

The occlusion of vessels by packed Plasmodium falciparum-infected (iRBC) and uninfected erythrocytes is a characteristic postmortem finding in the microvasculature of patients with severe malaria. Here we have employed immunocompetent Sprague-Dawley rats to establish sequestration in vivo. Human iRBC cultivated in vitro and purified in a single step over a magnet were labeled with 99mtechnetium, injected into the tail vein of the rat, and monitored dynamically for adhesion in the microvasculature using whole-body imaging or imaging of the lungs subsequent to surgical removal. iRBC of different lines and clones sequester avidly in vivo while uninfected erythrocytes did not. Histological examination revealed that a multiadhesive parasite adhered in the larger microvasculature, inducing extensive intravascular changes while CD36- and chondroitin sulfate A-specific parasites predominantly sequester in capillaries, inducing no or minor pathology. Removal of the adhesive ligand Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), preincubation of the iRBC with sera to PfEMP1 or preincubation with soluble PfEMP1-receptors prior to injection significantly reduced the sequestration. The specificity of iRBC binding to the heterologous murine receptors was confirmed in vitro, using primary rat lung endothelial cells and rat lung cryosections. In offering flow dynamics, nonmanipulated endothelial cells, and an intact immune system, we believe this syngeneic animal model to be an important complement to existing in vitro systems for the screening of vaccines and adjunct therapies aiming at the prevention and treatment of severe malaria.     

The Arabidopsis PILZ group genes encode tubulin-folding cofactor orthologs required for cell division but not cell growth

Plant microtubules are organized into specific cell cycle-dependent arrays that have been implicated in diverse cellular processes, including cell division and organized cell expansion. Mutations in four Arabidopsis genes collectively called the PILZ group result in lethal embryos that consist of one or a few grossly enlarged cells. The mutant embryos lack microtubules but not actin filaments. Whereas the cytokinesis-specific syntaxin KNOLLE is not localized properly, trafficking of the putative auxin efflux carrier PIN1 to the plasma membrane is normal. The four PILZ group genes were isolated by map-based cloning and are shown to encode orthologs of mammalian tubulin-folding cofactors (TFCs) C, D, and E, and associated small G-protein Arl2 that mediate the formation of alpha/beta-tubulin heterodimers in vitro. The TFC C ortholog, PORCINO, was detected in cytosolic protein complexes and did not colocalize with microtubules. Another gene with a related, although weaker, embryo-lethal phenotype, KIESEL, was shown to encode a TFC A ortholog. Our genetic ablation of microtubules shows their requirement in cell division and vesicle trafficking during cytokinesis, whereas cell growth is mediated by microtubule-independent vesicle trafficking to the plasma membrane during interphase.     

Mosaicism of the CAG repeat sequence in the Huntington disease gene in a pair of monozygotic twins

We report on a pair of monozygotic twins belonging to a family segregating Huntington disease (HD). In routine DNA analysis of blood cells, they displayed three alleles of the CAG repeat sequence in the HD gene. Two different cell lines, carrying the normal allele together with either an expanded allele with 47 CAGs or an intermediate allele with 37 CAGs, were detected in blood and buccal epithelium from both twins. To our knowledge, this is the first case described of HD gene CAG repeat length mosaicism in blood cells. Haplotype analysis established that the 37 CAG allele most likely arose by contraction of the maternal 47 CAG allele. The contraction must have taken place postzygotically, possibly at a very early stage of development, and probably before separation of the twins. One of the twins has presented symptoms of HD for 4 years; his skin fibroblasts and hair roots carried only the cell line with the 47 CAG repeat allele. The other twin, who is without symptoms at present, displayed mosaicism in skin fibroblasts and hair roots. If the proportion of the two cell lines in the brain of each twin resembles that of their hair roots (another tissue originating from the ectoderm), the mosaicism in the unaffected twin would mean that only a part of his brain cells carried the expanded allele, which could explain why he, in contrast to his brother, has no symptoms at this time.     

High-throughput single strand conformation polymorphism mutation detection by automated capillary array electrophoresis: validation of the method

Capillary array electrophoresis (CAE) is a novel technique, which allows for high throughput analysis of DNA fragments. When screening for mutations in whole populations or large patient groups it is necessary to have robust and well-characterized setups for high throughput analysis. For large-scale mutation screening, we have developed procedures for single strand conformation polymorphism (SSCP) assays using CAE (CAE-SSCP) whereby we may increase both the sensitivity and the throughput compared to conventional SSCP analysis. In this study we have validated CAE-SSCP by 1) comparing detection by slab-gel based SSCP with CAE-SSCP of mutations in the MYH7, MYL2, and MYL3 genes encoding sarcomere proteins from patients suffering from hypertrophic cardiomyopathy; and 2) by constructing a series of 185 mutants having substitution mutations, as well as insertion/deletion mutations, or some combinations of these, in different sequence contexts in four exons and different positions relative to the end of the amplicon (three from the KCNQ1 gene, encoding a cardiac potassium channel, and one from the TNNI3 gene encoding cardiac troponin I). The method identified 181 out of 185 mutations (98%), and the data suggest that the position of mutation in the fragment had no effect on the sensitivity. Analysis of the specificity of the method showed that only very few mutants could not be distinguished from each other and there were no false positives.     

Progenitor cells in liver regeneration: molecular responses controlling their activation and expansion

Although normally quiescent, the adult mammalian liver possesses a great capacity to regenerate after different types of injuries in order to restore the lost liver mass and ensure maintenance of the multiple liver functions. Major players in the regeneration process are mature residual cells, including hepatocytes, cholangiocytes and stromal cells. However, if the regenerative capacity of mature cells is impaired by liver-damaging agents, hepatic progenitor cells are activated and expand into the liver parenchyma. Upon transit amplification, the progenitor cells may generate new hepatocytes and biliary cells to restore liver homeostasis. In recent years, hepatic progenitor cells have been the subject of increasing interest due to their therapeutic potential in numerous liver diseases as alternative or supportive/complementary tools to liver transplantation. While the first investigations on hepatic progenitor cells have focused on their origin and phenotypic characterization, recent attention has focused on the influence of the hepatic microenvironment on their activation and proliferation. This microenvironment comprises the extracellular matrix, epithelial and non-epithelial resident liver cells, and recruited inflammatory cells as well as the variety of growth-modulating molecules produced and/or harboured by these elements. The cellular and molecular responses to different regenerative stimuli seem to depend on the injury inflicted and consequently on the molecular microenvironment created in the liver by a certain insult. This review will focus on molecular responses controlling activation and expansion of the hepatic progenitor cell niche, emphasizing similarities and differences in the microenvironments orchestrating regeneration by recruitment of progenitor cell populations or by replication of mature cells.     

Isolierung und Charakterisierung von DNA-Abbaumutanten bei Proteus mirabilis: Funktion der Endonuclease I im postmortalen DNA-Abbau

DNase deficient mutants of Proteus mirabilis selected for reduced toluene induced DNA degradation were isolated. Their defect in DNA degradation was shown not only after treatment by toluene but also in crude extracts after cell disintegration by ultrasonic and in untreated starved cultures. The degradation mutants behave just as the wild type with respect to their in vivo functions proofed. The results indicate that the affected DNase does not have an essential function in vivo but acts in postmortem DNA degradation. Probably, the DNase in question concerns the endonuclease I of P. mirabilis described by GOEBEL and HELINSKI (1971 a, b).     

Neuropsychological aspects of cognitive functioning in epileptic children and adolescents treated with lamotrigine

The aim of our study was to examine the influence of long term lamotrigine (LTG) add-on therapy on higher nervous function in patients at the developmental age with epilepsy and to analyse the correlation between changes in EEG and cognitive parameters as a consequence of applying LTG in bi- or polytherapy with conventional antiepileptic drugs (AEDs). There were 25 patients (pts), 8-18 years of age with epilepsy stated as "difficult to treat" with partial (12 pts) and generalised (13 pts) seizures. The frequency of seizures was estimated as one or more per month last year (before LTG treatment). The mean age of the patients who had the first seizure was 4.7 yrs. Doses of LTG were adjusted individually (depending on conventional AEDs) according to the recommendation of the producer. The serum levels of conventional AEDs were checked during LTG therapy. Psychological examination was administered three times: before introduction of LTG (as add-on drug) to the therapy, after 3- and after 16 months of the treatment. We measured the level of intelligence, short-term memory, attention, visuomotor integration and abilities of learning. EEG was recorded by Ceegraph (Biologic, USA) after 3 and 12 months of LTG treatment. After the treatment no statistically significant differences in Intelligence Quotient (IQ): global, verbal, nonverbal were noticed. Statistical significance has been stated in parameters of short-term memory. The number of seizures decreased more than 50% in 12 pts. EEG records improved in 6 pts (normalisation of background activity), minimising of epileptform discharges has been noticed in 3 pts. LTG introduced into polytherapy of epilepsy in children and adolescents modified EEG and had minimal influence on cognitive functions.