Further evidence that the KIAA0319 gene confers susceptibility to developmental dyslexia

The DYX2 locus on chromosome 6p22.2 is the most replicated region of linkage to developmental dyslexia (DD). Two candidate genes within this region have recently been implicated in the disorder: KIAA0319 and DCDC2. Variants within DCDC2 have shown association with DD in a US and a German sample. However, when we genotyped these specific variants in two large, independent UK samples, we obtained only weak, inconsistent evidence for their involvement in DD. Having previously found evidence that variation in the KIAA0319 gene confers susceptibility to DD, we sought to refine this genetic association by genotyping 36 additional SNPs in the gene. Nine SNPs, predominantly clustered around the first exon, showed the most significant association with DD in one or both UK samples, including rs3212236 in the 5' flanking region (P = 0.00003) and rs761100 in intron 1 (P = 0.0004). We have thus refined the region of association with developmental dyslexia to putative regulatory sequences around the first exon of the KIAA0319 gene, supporting the presence of functional mutations that could affect gene expression. Our data also suggests a possible interaction between KIAA0319 and DCDC2, which requires further testing.

Towards many colors in FISH on 3D-preserved interphase nuclei

The article reviews the existing methods of multicolor FISH on nuclear targets, first of all, interphase chromosomes. FISH proper and image acquisition are considered as two related components of a single process. We discuss (1) M-FISH (combinatorial labeling + deconvolution + wide-field microscopy); (2) multicolor labeling + SIM (structured illumination microscopy); (3) the standard approach to multicolor FISH + CLSM (confocal laser scanning microscopy; one fluorochrome - one color channel); (4) combinatorial labeling + CLSM; (5) non-combinatorial labeling + CLSM + linear unmixing. Two related issues, deconvolution of images acquired with CLSM and correction of data for chromatic Z-shift, are also discussed. All methods are illustrated with practical examples. Finally, several rules of thumb helping to choose an optimal labeling + microscopy combination for the planned experiment are suggested.

Mitochondrial mutation detection using enhanced multiplex denaturing high-performance liquid chromatography

In this study, we investigated the presence of mutations within the mitochondrial genome in 40 Caucasian subjects using an enhanced multiplex denaturing high-performance liquid chromatography (DHPLC) approach. The enhanced DHPLC approach has increased sensitivity and throughput, and reduced analysis time per individual sample compared to conventional methods. This technique involved amplifying the mitochondrial genome in 18 fragments ranging in size from 300 to 2000 bp using a novel proofreading polymerase (Optimase, Transgenomic Inc., Omaha, NE) with a low misincorporation rate. Fourteen of these fragments underwent subsequent restriction digestion using a combination of five restriction enzymes to enable multiplex DHPLC analysis; the remaining four underwent conventional DHPLC. Using this complete mitochondrial genome-screening approach, we confirmed a number of previously reported mutations and additionally identified a large number of novel mutations using an enhanced DHPLC technique.

Repetitive elements in imprinted genes

Genomic imprinting in mammals results in mono-allelic expression of about 80 genes depending on the parental origin of the alleles. Though the epigenetic mechanisms underlying imprinting are rather clear, little is known about the genetic basis for these epigenetic mechanisms. It is still rather enigmatic which sequence features discriminate imprinted from non-imprinted genes/regions and why and how certain sequence elements are recognized and differentially marked in the germlines. It seems likely that specific DNA elements serve as signatures that guide the necessary epigenetic modification machineries to the imprinted regions. Inter- and intraspecific comparative genomic studies suggest that the unusual occurrence and distribution of various types of repetitive elements within imprinted regions may represent such genomic imprinting signatures. In this review we summarize the various observations made and discuss them in light of experimental data.

Oncogenic HRAS suppresses clusterin expression through promoter hypermethylation

Silencing of gene expression by methylation of CpG islands in regulatory elements is frequently observed in cancer. However, an influence of the most common oncogenic signalling pathways onto DNA methylation has not yet been investigated thoroughly. To address this issue, we identified genes suppressed in HRAS-transformed rat fibroblasts but upregulated after treatment with the demethylating agent 5-Aza-2-deoxycytidine and with the MEK1,2 inhibitor U0126. Analysis of gene expression by microarray and Northern blot analysis revealed the MEK/ERK target genes clusterin, matrix metalloproteinase 2 (Mmp2), peptidylpropyl isomerase C-associated protein, syndecan 4, Timp2 and Thbs1 to be repressed in the HRAS-transformed FE-8 cells in a MEK/ERK- and methylation-dependent manner. Hypermethylation of putative regulatory elements in HRAS-transformed cells as compared to immortalized fibroblasts was detected within a CpG island 14.5 kb upstream of clusterin, within the clusterin promoter and within a CpG island of the Mmp2 promoter by bisulphite sequencing. Furthermore, hypermethylation of the clusterin promoter was observed 10 days after induction of HRAS in immortalized rat fibroblasts and a clear correlation between reduced clusterin expression and hypermethlyation could also be observed in distinct rat tissues. These results suggest that silencing of individual genes by DNA methylation is controlled by oncogenic signalling pathways, yet the mechanisms responsible for initial target gene suppression are variable.

Parapoxvirus-Infektion am Euter eines Rindes

Ziel: Der Fallbericht beschreibt die diagnostischen Möglichkeiten bei Verdacht auf Euterpocken und erörtert die Therapie beim Einzeltier sowie Maßnahmen zur Bestandssanierung. Falldarstellung: In der Klinik wurde eine primipare Fleckviehkuh 18 Tage post partum mit hochgradig krustösen Veränderungen an den Hinterzitzen vorgestellt. Im Bestand wiesen ca. 20% der Tiere Zitzenläsionen geringerer Ausprägung auf. Neben der allgemeinen klinischen und labordiagnostischen Untersuchung wurde eine histologische Untersuchung des veränderten Gewebes durchgeführt. MittelsVirusanzüchtung und Elektronenmikroskopie sollte ein Erregernachweis erfolgen. Ergebnisse: Die Virusanzüchtung war erfolgreich und elektronenmikroskopisch konnte die Diagnose einer Infektion mit Parapoxvirus gestellt werden. Histopathologisch ließ sich verhorntes Epithel mit Bakterienkolonien nachweisen. Die Blutuntersuchung ergab eine Leukozytose mit Neutrophilie. Das Tier wurde lokal und systemisch antibiotisch trockengestelltund parenteral mit einem Paramunitätsinducer behandelt. Die lokale Versorgung der betroffenen Zitzen erfolgte mit Lebertranzinksalbe. Die Läsionen heilten unter der Therapie so weitaus, dass sechs Wochen nach Vorstellung nur noch Narben zu erkennen waren. Zur Bestandssanierung wurden allgemeine Hygiene- und Desinfektionsmaßnahmen sowie die Anwendung eines jodophoren Zitzendippings angeraten. Schlussfolgerung und klinische Relevanz: Euterpocken sind eine zwar weit verbreitete, aber seltener zweifelsfrei diagnostizierte Infektion an der Zitze des Rindes. Die Diagnose lässt sich mithilfe der Elektronenmikroskopie stellen. Die Prognose aufeine Genesung des Einzeltieres unter der Therapie stellt sich als gut dar. Eine Sanierung des infizierten Bestandes ist nur unter strengsten Hygiene- und Desinfektionsmaßnahmen zu erreichen. Um der Einschleppung in eine Herde vorzubeugen, empfiehlt sich eine Einstallungsquarantäne.

131 DYNAMICS OF HISTONE H3 METHYLATION AT POSITIONS K4 AND K9 IN MOUSE, RABBIT, AND BOVINE PRE-IMPLANTATION EMBRYOS

In mammals, upon the penetration of sperm into the oocyte, the paternal genome undergoes dramatic epigenetic changes. Protamin packaging of DNA is replaced by histones that acquire specific modifications. In mouse zygotes, paternal DNA gets rapidly demethylated by an active mechanism. In bovine zygotes the methylation from paternal DNA is erased only partially, and in rabbit zygotes it persists at the initial level. To understand whether these reprogramming differences are also reflected in histone modifications, we examined the dynamic changes of histone H3 methylation at positions K4 and K9 in mouse, bovine, and rabbit zygotes and in preimplantation embryos using an immunofluorescence staining procedure (Lepikhov and Walter 2004 BMC Dev. Biol. 4, 12). In zygotes, maternal chromatin contains both types of histone H3 methylation. After fertilization protamines in sperm are very quickly replaced by histones. After the formation of nucleosomes, histone H3 acquires methylation at position K4 in a stepwise manner: first as mono-methylated form and later as tri-methylated. In the late zygote, both paternal and maternal pronuclei show equal levels of histone H3 methylation at position K4. Regardless of the differences in DNA reprogramming in these 3 species, H3/K9 di-methylation is not detected on paternal genomes and is only associated with maternal genomes. During the subsequent cleavage stages, H3/K9 di-methylation decreases gradually and becomes hardly detectable in 4-cell bovine and rabbit embryos. In mouse embryos, it is detectable through all the stages. Bovine embryos reacquire this type of modification at the 8-16 cell stage, and it remains at the very low levels in rabbit, embryos until the blastocyst stage. In conclusion, mouse, rabbit and bovine zygotes show similar patterns of H3/K4triMe and H3/K9diMe distribution despite the difference in paternal DNA demethylation. The dynamics of H3/K9diMe distribution patterns in cleavage stage embryos from all embryos do not correlate with embryonic genomic activation events.

Risikostratifizierung diabetischer Koronarpatienten—

Among the coronary bypass patients from our Datamart database, we found a prevalence of 29.6% of diagnosed diabetics. 5.2% of the patients without a diagnosis of diabetes mellitus and a fasting plasma glucose level > 125 mg/dl were defined as undiagnosed diabetics. The objective of this paper was to compare univariate methods and techniques for risk stratification to determine, whether undiagnosed diabetes is per se a risk factor for increased ventilation time and length of ICU stay, and for increased prevalence of resuscitation, reintubation and 30-d mortality for diabetics in heart surgery. Univariate comparisons reveals that undiagnosed diabetics needed resuscitation significantly more often and had an increased ventilation time, while the length of ICU stay was significantly reduced. The significantly different distribution between the diabetics groups of 11 from 32 attributes examined, demands the use of methods for risk stratification. Both risk adjusted methods regression and matching confirm that undiagnosed diabetics had an increased ventilation time and an increased prevalence of resuscitation, while the length of ICU stay was not significantly reduced. A homogeneous distribution of the patient characteristics in the two diabetics groups could be achieved through a statistical matching method using the propensity score. In contrast to the regression analysis, a significantly increased prevalence of reintubation in undiagnosed diabetics was found. Based on an example of undiagnosed diabetics in heart surgery, the presented study reveals the necessity and the possibilities of techniques for risk stratification in retrospective analysis and shows how the potential of data collection from daily clinical practice can be used in an effective way.

[Hepatitis B and C risk factors in Germany--results of the national surveillance]

Collection of risk factor data is part of the national surveillance of hepatitis B and C in Germany. After modifications of risk factor surveillance had been implemented in September 2003, the response rate for data on risk factors increased markedly. For the period between September 2003 and August 2004, information on risk factors (at least one "yes" or "no" answer) was available for 66% (1853) of all notified hepatitis B cases and for 67% (5813) of all notified hepatitis C cases. More than 30% of those hepatitis B cases occurred among risk groups for whom hepatitis B immunisation is recommended by the German Advisory Committee on Immunisation (STIKO). Of the hepatitis C cases with risk factor data, 40% reported previous or continuing injecting drug use (IDU). IDU was predominant among young men (78% among men, aged 15 to 29 years) and can explain the comparatively high incidence observed in young adults, especially among men. The impact of other risk factors (e. g. medical interventions) cannot be quantified without a proper control group. The results of this study demonstrate that--in addition to the hepatitis B immunisation of children and adolescents--vaccination coverage of specific risk groups, as defined by the STIKO, should be increased. Measures to prevent hepatitis C have to focus on intravenous drug users and clearly have to be intensified.

[Supratentorial cavernoma and epileptic seizures. Are there predictors for postoperative seizure control?]

For cavernous haemangiomas, it is the aim of surgical treatment to control epilepsy and eliminate potential sources of intracerebral haematomas. In the following investigation, it was attempted to find indicators for seizure freedom after surgery. Success of therapy was assessed according to three patterns of classification. Thirty patients underwent tailored resection based on findings from preoperative investigations and intraoperative electrocorticography. Follow-up averaged 4 years. Lesionectomy, extended lesionectomy, and modified lobe resection were carried out in 13, 11, and six patients, respectively. For all procedures, including microsurgical lesionectomy, the firm gliotic layer unequivocally differed in colour and consistency from normal brain and was removed. Further tissue resection was carried out only if the electrocortical course suggested persistent spike activity around the resection cavity or if presurgical MRI evaluation (e.g. hippocampal atrophy) or electrophysiology also pointed to pathology distant from the lesion. Of the patients, 53.3% became completely seizure-free (Engel I), and one additional patient had only occasional isolated auras. Dramatic reductions in seizure frequency and severity were exhibited by 26.7%. Outcome in respect to seizure control was not associated with resection procedure, comparing pure lesionectomy with lesionectomy plus cortectomy. In the group of patients with epilepsy surgery, those with hippocampectomy had significantly better outcome than those without. Important prognostic factors were early operation after seizure manifestation (91.7% operated upon within 2 years of seizure onset became seizure-free). Another prognostic factor was unifocal seizure onset (bilateral or multifocal seizure onset was found in care of the ten patients with unfavourable outcome). None of the four patients harbouring multiple cavernomas became seizure-free after resection of one lesion, which was believed to be mostly attributable to the epileptic focus that was removed.

Magnetoencephalography (MEG) predicts focal epileptogenicity in cavernomas

OBJECTIVE

The aim of this study was to identify the irritative epileptic zone in patients with cavernomas by means of magnetoencephalography (MEG).

METHOD

Among 82 patients operated for epilepsy, whose presurgical evaluation had included MEG, histological assessment of the tissue removed had confirmed cavernomas in eight. These eight patients had epilepsy since 18.6 (SD 12.7) years on average. The monitoring lasted about 2.1 (SD 1.3) hours and a median 20.9 (SD 14.3) spikes per hour were recorded. Spontaneous brain activity was recorded by means of a 74 channel dual unit MEG system (Magnes II, 4-D Neuroimaging) with simultaneous EEG recording (31 scalp electrodes). Spike analysis was performed using different source (moving dipole, current density reconstruction) and head models (spherical shells, BEM). Co-registration of neurophysiological and imaging data (MRI) was based upon anatomical landmarks.

RESULTS

In 6/8 patients co-localisation from the cavernoma and epileptic zone was found. In two patients the focus was localised in the parieto-occipital lobe, in three patients in the frontal lobe and in three patients in the temporal lobe. In one case of temporal and one case of frontal lobe focus localisation there was no spatial relationship to the cavernoma.

CONCLUSION

In cases of focal seizures due to a single cavernoma, MEG may precisely delineate the epileptogenic tissue bordering the lesion. In patients with multiple cavernomas or dual pathology, MSI may reveal the complexity of the case, and contribute to the decision about further invasive diagnostics and more sophisticated therapeutic measures. MEG is a promising method for prediction of the epileptic zone in cavernoma related epilepsies, and thus it can contribute to decision making about and planning of epilepsy surgery.