Prevalence and complications of MRI scans of cochlear implant patients : English version.

BACKGROUND: Cochlear implants (CI) are the preferred method of treatment for patients with severe to profound bilateral sensorineural hearing loss and unilateral deafness. For many years, because of the magnetic field applied during magnetic resonance imaging (MRI) examinations, MRI examinations were contraindicated for CI patients or feasible only under specific circumstances. MRI examinations of CI recipients entail complications and therefore preventive measures have to be considered. The aim of this study was to evaluate the prevalence of MRI scans in CI recipients and the occurrence of complications and furthermore to investigate the preventive measures taken in radiological daily routine. MATERIALS AND METHODS: A retrospective questionnaire was sent to 482 patients that received CIs from 1999-2013. Details of the MRI examination and subjective and objective incidents during and after the MRI scan were evaluated. RESULTS: A total of 204 CI recipients answered the retrospective questionnaire (42.3 %). Twenty patients (9.8 %) with 23 implants underwent a total of 33 MRI scans with their cochlear implant in place. In 16 cases the scanned region was the head (49 %). Preventive measures in the form of head bandages were taken in 20 cases (61 %). The most common complication was pain in 23 cases (70 %) and the most serious complication was the dislocation of the internal magnet in 3 cases (9 %). CONCLUSIONS: The number of CI recipients undergoing MRI scans is high. Possible complications and preventive measures attract too little attention in radiological daily routine.

Genetic selection to increase bone strength affects prevalence of keel bone damage and egg parameters in commercially housed laying hens.

The prevalence of keel bone damage as well as external egg parameters of 2 pure lines divergently selected for high (H) and low (L) bone strength were investigated in 2 aviary systems under commercial conditions. A standard LSL hybrid was used as a reference group. Birds were kept mixed per genetic line (77 hens of the H and L line and 201 or 206 hens of the LSL line, respectively, per pen) in 8 pens of 2 aviary systems differing in design. Keel bone status and body mass of 20 focal hens per line and pen were assessed at 17, 18, 23, 30, 36, 43, 52, and 63 wk of age. External egg parameters (i.e., egg mass, eggshell breaking strength, thickness, and mass) were measured using 10 eggs per line at both 38 and 57 wk of age. Body parameters (i.e. tarsus and third primary wing feather length to calculate index of wing loading) were recorded at 38 wk of age and mortality per genetic line throughout the laying cycle. Bone mineral density (BMD) of 15 keel bones per genetic line was measured after slaughter to confirm assignment of the experimental lines. We found a greater BMD in the H compared with the L and LSL lines. Fewer keel bone fractures and deviations, a poorer external egg quality, as well as a lower index of wing loading were found in the H compared with the L line. Mortality was lower and production parameters (e.g., laying performance) were higher in the LSL line compared with the 2 experimental lines. Aviary design affected prevalence of keel bone damage, body mass, and mortality. We conclude that selection of specific bone traits associated with bone strength as well as the related differences in body morphology (i.e., lower index of wing loading) have potential to reduce keel bone damage in commercial settings. Also, the housing environment (i.e., aviary design) may have additive effects.

[Prevalence and complications of MRI scans of cochlear implant patients: German version]. / Häufigkeit und Komplikationen von MRT-Untersuchungen bei Cochlea-Implantat-Patienten: German version.

BACKGROUND: Cochlear implants (CI) are the preferred method of treatment for patients with severe to profound bilateral sensorineural hearing loss and unilateral deafness. For many years, because of the magnetic field during magnetic resonance imaging (MRI) examinations, MRI examinations were contraindicated for CI patients or feasible only under specific circumstances. MRI examinations of CI recipients entail complications and therefore preventive measures have to be considered. The aim of this study was to evaluate the incidence of MRI scans in CI recipients and the occurrence of complications, and furthermore to investigate the preventive measures taken in radiological daily routine. MATERIALS AND METHODS: A retrospective questionnaire was sent to 482 patients that received CIs from 1999-2013. Details of the MRI examination and subjective and objective incidents during and after the MRI scan were evaluated. RESULTS: A total of 204 CI recipients answered the retrospective questionnaire (42.3%). Twenty patients (9.8%) with 23 implants underwent a total of 33 MRI scans with their cochlear implant in place. In 16 cases the scanned region was the head (49%). Preventive measures in the form of head bandages were taken in 20 cases (61%). The most common complication was pain in 23 cases (70%) and the most serious complication was the dislocation of the internal magnet in 3 cases (9%). CONCLUSIONS: The number of CI recipients undergoing MRI scans is quite high. Possible complications and preventive measures attract too little attention in radiological daily routine.

Providing ramps during lay has larger impacts on laying hens than ramps at rearing.

Commercial laying hen housing is shifting from traditional cages to non-cage housing systems, such as the aviary, which has gained popularity due to potential for more species-typical behavior. However, birds housed in aviaries may have difficulties moving through the vertical tiers of the system leading to health problems such as keel bone fracture (KBF). One possible way to improve movement is to add ramps into an aviary system, allowing hens to walk between tiers rather than jump or fly. The objective of this study was to evaluate the impact of adding ramps to rearing and laying aviaries on bird health, production, and movement across vertical tiers of the aviary. Lohmann Selected Leghorn pullets were raised in 2 treatments: 4 pens (600 birds/pen) were raised with wire mesh ramps to aid movement between aviary tiers (RR) and 4 pens (600 birds/pen) were raised without ramps (RO). At 17 wk of age (WOA), birds were moved to the laying facility, in which 16 aviary pens with 225 birds/pen were populated. Half the pens (n = 8) were supplemented with wire mesh ramps (LR) and the other half were not (LO). Within each laying treatment group, 4 pens were populated with RR hens and 4 pens were populated with RO hens, creating 4 treatment combinations (RRLR, RRLO, ROLR, ROLO). From each pen, 15 focal hens were selected for radiographic imaging of their keel bones taken at 21, 36, 45, and 60 WOA and the images were subsequently scored for KBF severity. Focal hens were also scored for feather condition and footpad quality at 36 and 60 WOA using a standardized welfare assessment protocol. The number of downward transitions among aviary areas and falls were recorded at 19 to 20 and 30 to 31 WOA. Data were analyzed using (generalized) linear mixed models in R software. When ramps were available, they were used in most of the observed downward transitions (79% in ROLR and 86% in RRLR). Hens who received ramps in lay (i.e., RRLR and ROLR) showed more transitions immediately after lights on compared to midday or dusk phases (p < 0.001), performed more transitions from the first aviary tier compared to nest or top tier (p = 0.013) and had lower KBF severity than those who did not receive ramps in the laying aviaries (ROLO, RRLO; p < 0.001). At 60 WOA, hens in the RRLR treatment had greater feather coverage than those in ROLR and RRLO treatments (p < 0.001). Birds in the RRLR treatment had better foot health overall than those in treatments without ramps in lay (p = 0.018). Providing ramps to hens in aviaries appeared to be the preferred means of transitioning between aviary tiers though had positive effects on welfare parameters such as food health, feather coverage, and KBF severity, without negative impacts on production. Benefits were seen primarily when ramps were provided in lay, though their installation in rearing provided evidence of easier adaptation to the laying barn. Our study supports providing ramps throughout the lifetime of the bird to accommodate hens' preferred means of moving vertically in aviaries and deliver consequent benefits to health and welfare.

The potential of a light spot, heat area, and novel object to attract laying hens and induce piling behaviour.

Piling behaviour of laying hens often results in smothering or death due to suffocation. Mechanisms leading to piling are not yet understood though various potential factors have been suggested. In this experimental study, we predicted that the presence of a light spot, a novel object (metal foil), or a heat area within animal pens would increase animal numbers around the stimulus leading to piling behaviour. We presented the cues in a 4 × 2 Latin-square design in eight identical experimental pens including each 55 Lohmann Selected Leghorn hens. The cues were presented in two test areas per pen, at two bouts per day in the morning, consecutively for 5 days, over four periods (age: 20, 22, 24, 26 weeks). Each pen received a cue and control condition simultaneously (test areas without cue presentation) once. For a bout, each cue was presented for 35 min except for the light spot where the duration was 10 min. Birds' responses to the cues during bout and non-bout times were video recorded and analysed for the first bout of each period. To assess the cues' attractiveness, the number of hens during bout times was counted at predefined times within the test and control areas. To assess the cues' effects on piling, we described piling behaviour (pile number, duration, animal numbers, trigger) in control and test areas during bout times. Furthermore, we described piling behaviour during bout times and non-bout times on the first day of the first period and fourth period. The best model explaining the number of hens included the interactions of treatment and bout time, and treatment and area. Over the bout's time course, more hens were attracted to the light spot compared to the control condition, and more to test areas compared to control areas. In the novel object condition, more hens were drawn to the test areas compared to the control areas. Hens were not attracted to the heat area. Piling in bout times was observed twice when hens pecked at the novel object. During non-bout times, piling behaviour occurred frequently at midday and in the late morning compared to the afternoon, mostly in corners and mainly preceded by the mutual attraction of hens. Overall, hens were attracted to light spots and less so to the novel object though neither reliably induced piling behaviour. The occurrence of piling behaviour in non-bout times shows that more work is needed to understand mechanisms eliciting piling behaviour.

MRI-Based Estimation of Scalar Cochlear-Implant Electrode Position.

The position of the cochlear-implant electrode is important to audiological outcomes after cochlear implantation. The common technique to evaluate the intracochlear electrode's position involves the use of ionized radiation in MSCT, DVT, or flat-panel tomography (FPT). Recent advances in knowledge regarding the handling of MRI artifacts in cochlear implantees indicate that estimating the intracochlear electrode's position with an MRI could be possible. This study's aim was to evaluate the ipsilaterally position of electrodes using MRI at 1.5 T. In a retrospective study of 10 implantees with postoperative need for MRI scanning, we evaluated the intrascalar electrode's position using a T2-weighted sequence at 1.5 T. We compared the resulting estimate of the intracochlear position with the estimates from the postoperative FPT scan and the intraoperative NRT ratio. For each ear, the MRI-estimated scalar position corresponded with the estimated positions from the FPT and NRT ratio. For eight ears, a scala tympani's position was observed in the MRI. In one case, an electrode scalar translocation was found. In one case, the scala vestibuli's position was observed. Thus, MRI-based estimation of the scalar position of a cochlear-implant electrode is possible. Limitations to this method include implant-specific magnet and fixation configurations, which can cause complications.

The biosynthetic gene cluster for the microtubule-stabilizing agents epothilones A and B from Sorangium cellulosum So ce90.

BACKGROUND: Epothilones are produced by the myxobacterium Sorangium cellulosum So ce90, and, like paclitaxel (Taxol((R))), they inhibit microtubule depolymerisation and arrest the cell cycle at the G2-M phase. They are effective against P-glycoprotein-expressing multiple-drug-resistant tumor cell lines and are more water soluble than paclitaxel. The total synthesis of epothilones has been achieved, but has not provided an economically viable alternative to fermentation. We set out to clone, sequence and analyze the gene cluster responsible for the biosynthesis of the epothilones in S. cellulosum So ce90. RESULTS: A cluster of 22 open reading frames spanning 68,750 base pairs of the S. cellulosum So ce90 genome has been sequenced and found to encode nine modules of a polyketide synthase (PKS), one module of a nonribosomal peptide synthetase (NRPS), a cytochrome P450, and two putative antibiotic transport proteins. Disruptions in the genes encoding the PKS abolished epothilone production. The first PKS module and the NRPS module are proposed to co-operate in forming the thiazole heterocycle of epothilone from an acetate and a cysteine by condensation, cyclodehydration and subsequent dehydrogenation. The remaining eight PKS modules are responsible for the elaboration of the rest of the epothilone carbon skeleton. CONCLUSIONS: The overall architecture of the gene cluster responsible for epothilone biosynthesis has been determined. The availability of the cluster should facilitate the generation of designer epothilones by combinatorial biosynthesis approaches, and the heterologous expression of epothilones in surrogate microbial hosts.

In vitro differentiation of trout oligodendrocytes: evidence for an A2B5-positive origin.

The molecular differentiation of oligodendrocytes derived from larval trout brain was studied in dissociated cell cultures using a range of cell type and stage specific antibodies. By double-labeling immunostaining using A2B5 antibodies in conjunction with antibodies against the myelin glycoproteins IP1 and IP2 evidence was obtained that oligodendrocytes of trout in vitro originate from A2B5+ precursor cells, which in terms of morphology closely resemble 0-2A progenitors of the mammalian CNS. Most surprisingly these cells did not differentiate in vitro beyond the level of IP2 expression, which signifies the initial step of oligodendroglial development in vivo. Hence it appears that in trout oligodendrocytes the initiation of the developmental program is intrinsically regulated, whereas further maturation of the cells requires appropriate environmental stimulation.

Anti-angiogenic gene therapy of malignant glioma.

Glioblastoma, one of the best vascularized tumours in humans, appears well suited for an antiangiogenic therapy. VEGF (vascular endothelial growth factor), the most important angiogenesis factor identified to date, is highly expressed in glioblastoma. VEGF is particulary upregulated in palisading cells adjacent to necroses and has subsequently been shown to be hypoxia-inducible in glioma cells in vitro. VEGF-receptor tyrosine kinases, VEGF-R1 (flt-1) and VEGF-R2 (flk-1), are induced in a tumour stage dependent manner during glioma progression and are exclusively expressed in tumour vascular endothelial cells. These observations suggest that VEGF-receptors are promising targets for tumour endothelial cell specific therapy. The ability to block VEGF-signalling by the VEGF-R2 dominant-negative mutant identifies the VEGF/VEGF-R2 system as a major regulator of glioma angiogenesis. Several experimental approaches demonstrate that in rat gliomas tumour growth can be prevented by the inhibition of angiogenesis. These findings are of pivotal importance for the development of anti-angiogenic therapies in glioblastoma patients.

Application of a proton microprobe to biomedical research : Limits and potentialities.

The capability of PIXE analysis to simultaneously detect trace elements with Z≥14, with a high power of detection, can be exploited in biomedical research if the diameter of the proton beam is reduced to micrometer dimensions. In this case, trace analyses of small particles or small parts of a larger specimen are rendered possible without deteriorating the detection limits of PIXE. The measurements yield a completely new type of information on the biological microstructure. In order to fully utilize the abilities of the combined method, however, sample preparation techniques, and irradiation procedures have to be adapted to each analysis problem. Examples of application of the Bochum Proton Microprobe will be used to demonstrate how and to what extent this can be achieved for different types of biomedical problems.

Molecular cloning and tissue expression of a cDNA encoding IP1--a P0-like glycoprotein of trout CNS myelin.

A full-length cDNA encoding a major structural glycoprotein of trout CNS myelin (IP1) was cloned and sequenced. The deduced amino acid sequence exhibited a significant structural homology with the P0 proteins of rat PNS and shark CNS. Sequence conservation was strongest in the extracellular domain, and it included the position of the two cysteine residues required for stabilization of an immunoglobulin-like secondary structure as well as those of the single N-glycosylation acceptor site. The cytoplasmic domain was shorter by 38 amino acids than those of rat and shark P0 and except for a high proportion of basic amino acids did not show any appreciable sequence homology. A single mRNA species of 2 kb was identified by northern blotting, which was expressed in brain tissue but not in liver. By in situ hybridization a selective labeling of myelinating glial cells in the trout CNS and PNS was revealed. The developmental appearance of the IP1 transcript closely coincided with a period of active myelin deposition in most regions of the trout brain.

[Compression sonography as a screening method in thrombosis diagnosis]. / Kompressionssonographie als Screening-Methode in der Thrombosediagnostik.

The incidence of thromboses in the leg was studied in 542 patients (220 women and 322 men, mean age 61 [15-88] years) in a medical intensive care unit who had routinely undergone ultrasound examinations of the venous system of the legs. Not previously known thromboses were demonstrated in 62 (11.4%) of patients, bilaterally in 27.4% of them. Thromboses were most frequent (28.8%) in patients with malignant disease, rarest (3.7%) in those with myocardial infarction. 45% of thromboses were located solely in the lower leg. Autopsy, performed in 87 of the patients, revealed recent pulmonary emboli in 14. In eight of them venous thrombosis had been diagnosed by ultrasound before death, while the total number of leg vein thromboses identified in the 87 patients was 11.

[Mononeuritis multiplex as initial manifestation of systemic granulomatosis]. / Mononeuritis multiplex als Erstmanifestation einer systemischen Granulomatose.

We report two young patients with a painful and rapidly progressive polyneuropathy of the mononeuritis multiplex type confiding them to bed. Extensive investigations led to the diagnosis of a granulomatosis in both: Churg-Strauss allergic granulomatosis in one and Wegener's granulomatosis in the other. The importance and frequency of peripheral nervous system manifestations in the presenting clinical pattern of a systemic granulomatosis and vasculitis are discussed. Their proper recognition with regard to available effective therapeutic measures is stressed.

Cell type-specific expression of angiopoietin-1 and angiopoietin-2 suggests a role in glioblastoma angiogenesis.

Glioblastomas are highly vascular tumors which overexpress the angiogenesis factor vascular endothelial growth factor (VEGF). VEGF and its receptors, VEGF-R1 and VEGF-R2, have been shown to be necessary for embryonic angiogenesis as well as for tumor angiogenesis. Recently, the angiopoietin/Tie2 receptor system has been shown to exert functions in the cardiovascular system that are distinct from VEGF but are also critical for normal vascular development. To assess the potential role of Tie2 and its ligands angiopoietin-1 and angiopoietin-2 in tumor vascularization, we analyzed their expression pattern in human gliomas. Tie-2 was up-regulated in tumor endothelium compared to normal human brain tissue. We further observed cell type-specific up-regulation of the message for both angiopoietin-1 and angiopoietin-2 in gliomas. Whereas Ang-1 mRNA was expressed in tumor cells, Ang-2 mRNA was detected in endothelial cells of a subset of glioblastoma blood vessels. Small capillaries with few periendothelial support cells showed strong expression of Angiopoietin-2, whereas larger glioblastoma vessels with many periendothelial support cells showed little or no expression. Although the function of Tie2 and its ligands in tumor angiogenesis remains a subject of speculation, our findings are in agreement with a recently proposed hypothesis that in the presence of VEGF, local production of Ang-2 might promote angiogenesis.

[Heart valve surgery: an analysis of the causes and peri- and postoperative course]. / Herzklappenreoperationen: Eine Analyse der Ursachen sowie des peri- und postoperativen Verlaufs.

From a total of 1,152 consecutive patients with heart valve replacement (1964-87) 108 patients (9.4%) had to be reoperated. Mechanical valves had to be replaced (n = 89) mainly because of perivalvular leakage followed by prosthetic stenosis and dysfunction. The lowest reoperation rate was found with Björk-Shiley prostheses (3.4%). Bioprostheses (reoperation rate 8.2%) had to be reoperated predominantly as a consequence of dysfunction. Ten years following implantation 30% of bioprostheses had to be replaced. Patients with reoperations demonstrated, in comparison to patients with singular valve replacement, no significant change in early mortality during the last 6 years (6.8% vs 5.4%). Furthermore, both patient groups revealed similar survival rates (10 years; 78% vs 76%) and improvement of life quality. However, non-lethal peri- and postoperative complication rates were higher in reoperated patients compared to patients with first valve replacement.

Differential inhibition of tumor angiogenesis by tie2 and vascular endothelial growth factor receptor-2 dominant-negative receptor mutants.

Tumor growth is angiogenesis-dependent. Current evidence suggests that vascular endothelial growth factor (VEGF), a major regulator of embryonic and hypoxia-mediated angiogenesis, is necessary for tumor angiogenesis. VEGF is expressed in tumor cells in vivo, and its tyrosine kinase receptors VEGFR-1 and VEGFR-2 are up-regulated in the tumor endothelium. A second endothelial cell-specific ligand/receptor tyrosine kinase system, consisting of the tie2 receptor, its activating ligand angiopoietin-1 and the inhibitory ligand angiopoietin-2, has been characterized. We have examined 6 human primary breast-cancer samples and 4 murine breast-cancer cell lines (M6363, M6378, M6444, M6468), transplanted into nude mice, by in situ hybridization and/or Northern analysis. Expression of angiopoietin-1, angiopoietin-2 and tie2 was compared to VEGF and VEGFR-2 expression. Human tumors expressed VEGFR-2 and tie2 but varied considerably in VEGF and angiopoietin-1/-2 expression. In the murine tumor models, we observed high heterogeneity of receptor and ligand expression. M6363 and M6378 tumors were analyzed in detail because they showed different expression of components of the tie2/angiopoietin signaling system. M6363 tumors expressed VEGF, VEGFR-2 and angiopoietin-2 but not tie2 or angiopoietin-1, suggesting activation of VEGFR-2 and inhibition of tie2 signaling pathways, whereas M6378 tumors expressed VEGF, VEGFR-2, tie2 and angiopoietin-1 but little angiopoietin-2, suggesting activation of both VEGFR-2 and tie2 signaling pathways. In vivo studies using truncated dominant-negative tie2 and VEGFR-2 mutants revealed inhibition of M6363 tumor growth by 15% (truncated tie2) and 36% (truncated VEGFR-2), respectively. In contrast, M6378 tumor growth was inhibited by 57% (truncated tie2) and 47% (truncated VEGFR-2), respectively. These findings support the hypothesis that tumor angiogenesis is dependent on VEGFR-2 but suggest that, in addition, tie2-dependent pathways of tumor angiogenesis may exist. For adequate application of angiogenesis inhibitors in tumor patients, analysis of prevailing angiogenesis pathways may be a prerequisite.

Molecular cloning, tissue expression, and partial characterization of the major fish CNS myelin protein 36k.

A full-length cDNA clone encoding the major structural protein of trout CNS myelin 36K was isolated and sequenced. The deduced amino acid sequence did not reveal a putative transmembrane domain and exhibited no structural homology with any of the known myelin proteins. 36K instead shared characteristic structural elements with enzymes of the short-chain dehydrogenase family. The highest similarity in the database (60%), however, was obtained with a human protein of unknown function. By Northern blotting, a single mRNA species of about 2 kb was identified, which was expressed in brain tissue but not in liver. By in situ hybridization, a selective labeling of myelinating glial cells in the trout CNS but not in the PNS was revealed. The developmental appearance of the 36K transcript closely coincided with a period of active myelin deposition in most regions of the trout brain. As a first step in elucidating the structural and biochemical role of 36K for myelin formation and maintenance, we have overexpressed it in Escherichia coli as a soluble His-tag fusion protein and purified it in high yield by Ni+-chelated affinity chromatography. By SDS-PAGE, a single band of the expected molecular size was revealed, which heavily cross-reacted with polyclonal antibodies generated against the native protein. The results of circular dichroism spectroscopy are compatible with a betaalphabeta-barrel structure (Rossman fold), confirming the results of computer-assisted secondary structure predictions.

Identification, cloning, expression, and characterization of the extracellular acarbose-modifying glycosyltransferase, AcbD, from Actinoplanes sp. strain SE50.

An extracellular enzyme activity in the culture supernatant of the acarbose producer Actinoplanes sp. strain SE50 catalyzes the transfer of the acarviosyl moiety of acarbose to malto-oligosaccharides. This acarviosyl transferase (ATase) is encoded by a gene, acbD, in the putative biosynthetic gene cluster for the alpha-glucosidase inhibitor acarbose. The acbD gene was cloned and heterologously produced in Streptomyces lividans TK23. The recombinant protein was analyzed by enzyme assays. The AcbD protein (724 amino acids) displays all of the features of extracellular alpha-glucosidases and/or transglycosylases of the alpha-amylase family and exhibits the highest similarities to several cyclodextrin glucanotransferases (CGTases). However, AcbD had neither alpha-amylase nor CGTase activity. The AcbD protein was purified to homogeneity, and it was identified by partial protein sequencing of tryptic peptides. AcbD had an apparent molecular mass of 76 kDa and an isoelectric point of 5.0 and required Ca(2+) ions for activity. The enzyme displayed maximal activity at 30 degrees C and between pH 6.2 and 6.9. The K(m) values of the ATase for acarbose (donor substrate) and maltose (acceptor substrate) are 0.65 and 0.96 mM, respectively. A wide range of additional donor and acceptor substrates were determined for the enzyme. Acceptors revealed a structural requirement for glucose-analogous structures conserving only the overall stereochemistry, except for the anomeric C atom, and the hydroxyl groups at positions 2, 3, and 4 of D-glucose. We discuss here the function of the enzyme in the extracellular formation of the series of acarbose-homologous compounds produced by Actinoplanes sp. strain SE50.

The AcbC protein from Actinoplanes species is a C7-cyclitol synthase related to 3-dehydroquinate synthases and is involved in the biosynthesis of the alpha-glucosidase inhibitor acarbose.

The putative biosynthetic gene cluster for the alpha-glucosidase inhibitor acarbose was identified in the producer Actinoplanes sp. 50/110 by cloning a DNA segment containing the conserved gene for dTDP-D-glucose 4,6-dehydratase, acbB. The two flanking genes were acbA (dTDP-D-glucose synthase) and acbC, encoding a protein with significant similarity to 3-dehydroquinate synthases (AroB proteins). The acbC gene was overexpressed heterologously in Streptomyces lividans 66, and the product was shown to be a C7-cyclitol synthase using sedo-heptulose 7-phosphate, but not ido-heptulose 7-phosphate, as its substrate. The cyclization product, 2-epi-5-epi-valiolone ((2S,3S,4S,5R)-5-(hydroxymethyl)cyclohexanon-2,3,4,5-tetrol), is a precursor of the valienamine moiety of acarbose. A possible five-step reaction mechanism is proposed for the cyclization reaction catalyzed by AcbC based on the recent analysis of the three-dimensional structure of a eukaryotic 3-dehydroquinate synthase domain (Carpenter, E. P., Hawkins, A. R., Frost, J. W., and Brown, K. A. (1998) Nature 394, 299-302).

[Development-dependent diagnosis in two children with a rare "combined disorder of school readiness" in accordance with ICD-10, F81.3]. / Entwicklungsbezogene Diagnostik bei zwei Kindern mit der seltenen "kombinierten Störung schulischer Fertigkeiten" gemäss ICD-10, F81.3.

The new category (ICD-10) of mixed disorder of scholastic skills (F81.3) includes the combination of specific reading and spelling disorders with specific disorder of arithmetical skills and the combination of specific spelling disorder with specific disorder of arithmetical skills. We could demonstrate such combinations of specific developmental disorders in two children. In addition to diagnostic approaches with standardized testing procedures we used a model that is based on the steps in the development of specific skills. This method can be helpful in determining what kinds of intervention would be most appropriate. Both children with mixed disorders of scholastic skills also had psychiatric disorders.