Glutamate acts at NMDA receptors on fresh bovine and on cultured human retinal pigment epithelial cells to trigger release of ATP

Efficient vesicle membrane recycling at presynaptic terminals is pivotal for preventing depletion and maintaining high firing rates in neuronal networks. We used a new approach, based on the combination of spectrally different optical probes, to investigate how stimulation determines the fate of synaptic vesicles after endocytosis. We found that in the small central synapses of rat hippocampal neurones low frequency stimulation (40 action potentials at 2 Hz) targets vesicles preferentially to vesicle pools that were kinetically faster. Vesicles taken up during endocytosis triggered by high frequency stimulation (400 action potentials, 20 Hz) were also placed in the back of the release queue. We performed a spatial analysis of the recycled vesicles in living hippocampal boutons using two spectrally different FM-dyes (FM1-43 and FM5-95). By using these consecutively, vesicles endocytosed by either stimulation protocol were labelled with a different colour. This revealed that the kinetic arrangement was also reflected in the spatial organization of vesicles within the bouton. Next, we identified the postsynaptic site of the active zone by transfecting the neurones with postsynaptic density protein PSD-95-CFP. The data from these triple colour experiments suggest that retrieval after low frequency stimulation keeps vesicles in a more confined region closer to the active zone as identified by PSD-95-CFP expression at the postsynaptic site.     

Effectiveness and nephrotoxicity of intravenous colistin for treatment of patients with infections due to polymyxin-only-susceptible (POS) gram-negative bacteria

The prospective case series study presented here was conducted to assess the outcome of patients with infections caused by polymyxin-only-susceptible (POS) gram-negative bacteria managed with intravenous colistin. Between July 2003 and April 2005 a total of 27 patients were infected with a POS gram-negative bacterium and received intravenous colistin at a dose of 2 million international units (MIU) (160 mg or 66.7 mg colistin base) every 8 h for a mean (±SD) duration of 13.9 (±7.5) days. Nine patients had ventilator-associated pneumonia and received, in addition to the intravenous colistin therapy, 1 MIU (80 mg or 33.3 mg colistin base) aerosolized colistin every 12 h for a mean (±SD) duration of 13 (±6.5) days. The predominant pathogens were Pseudomonas aeruginosa (n=17) and Acinetobacter baumannii (n=12); in two patients both pathogens were isolated from one clinical specimen. In-hospital mortality and clinical response were 15% and 85%, respectively. Colistin-associated nephrotoxicity was observed in two of the 27 patients. POS gram-negative pathogens represent a major threat for hospitalized patients. Colistin appears to be an effective and safe treatment, even in patients with severe underlying diseases.     

Comparative genomic hybridization (CGH) of augmentation cystoplasties

OBJECTIVE: Tumors arising within augmentation cystoplasties are aggressive, have poor prognosis and the majority are not detected at follow-up cystoscopy. Genetic changes in tumors precede morphological abnormalities. Therefore, the aim of this study was to investigate whether genetic abnormalities detected by comparative genomic hybridization (CGH) could be used to identify those patients with augmentation cystoplasties at increased risk of tumorigenesis. METHODS: Bladder biopsy samples were obtained from 16 augmentation cystoplasty patients both distant from and near to the enterovesical anastomosis. CGH was used to detect genetic abnormalities in DNA extracted from the biopsies, archival specimens of two augmentation cystoplasties and two de novo bladder adenocarcinomas. RESULTS: A greater number of amplifications on 2p, 3q, 8q, 9p, 17p, 18pq and 20pq, were observed in bladder biopsies obtained near to the enterovesical anastomosis compared to those taken distant to the suture line. CGH of archival augmentation cystoplasty tumor DNA indicated abnormalities at several loci with amplifications at 2q, 5q, 10p and 21pq, while deletions occurred at 5p and 16p. CONCLUSIONS: The results of this study suggest that the urothelium adjacent to the bladder and/or bowel anastomosis in augmentation cystoplasties is genetically unstable. Furthermore, longitudinal studies are required to establish whether or not patients exhibiting genetic instability following augmentation cystoplasty are at greater risk of developing tumors than those with genetically stable epithelia.     

Within-gene interaction between c.135 G/A genotypes and RET proto-oncogene germline mutations in HSCR families.

Hirschsprung disease (HSCR) is considered a model for a complex inheritance disorder. Several genes, including the major HSCR-susceptibility RET proto-oncogene, play an aetiological role in the development of HSCR. Genetic linkage analysis in familial HSCR with both long- and short-segment phenotypes has demonstrated a tight linkage to the RET locus, while the phenotype within a HSCR family is characterised by an incomplete penetrance or a variable extension of the aganglionosis. Therefore, additional genetic alterations of RET are postulated in the aetiology or modification of the HSCR phenotype. In this study, the coding region of all 21 exons of the RET proto-oncogene, including the flanking intronic sequences, were investigated by direct DNA sequencing in a HSCR population. We genotyped the c.135 G/A polymorphism and resolved haplotypes comprising the mutation locus and the c.135 G/A polymorphism. Twenty different mutations were detected in 18 of 76 HSCR patients. In ten families the mutations were inherited from the parents, while only four patients had a positive family history for the disease. Moreover, in all ten families an incomplete penetrance of the HSCR phenotype was observed. We have investigated the effect of the non-mutated wild-type allele as well as the c.135 G/A polymorphism on the phenotype within the HSCR families. Our findings support the notion that both RET alleles are involved in the pathogenesis of a subgroup of HSCR patients in a dose-dependent fashion. Additionally, we have shown a modifying effect of the c.135 G/A polymorphism on the HSCR phenotype within HSCR families.     

Mindestmengen

BACKGROUND: Consequences of the volume outcome relationship are controversial. Objectification based on data analysis is strongly needed. The aim of this publication was to analyse the effects of volume outcome reallocations based on German inpatient data. METHOD: The analysis based on inpatient data of the Krankenhauszweckverband Koeln, Bonn und Region (Hospital Association of the Cologne and Bonn Region) of 2002 and 2005. Relevant data sets were identified according to the effects of current German regulations on volume outcome on the special fields liver transplant, kidney transplant, complex pancreatic surgery, and complex oesophageal surgery. RESULTS: The effects of current German regulations on volume outcome results differed greatly between the four surgical specialities. There were fewer effects on kidney transplant, but due to an already very high level of centralisation 34% (oesophagus) and 8% (pancreas) of the hospitals stopped related surgery. This affected 8.9% (oesophagus) and 2.2% (pancreas) of related cases. CONCLUSION: Concentration and the formation of specialised medical centres are results of the implementation of volume outcome relationships. The quality of medical treatment does not automatically improve from this development. It is necessary to analyse any correlation between quality and frequency of treatment or other criteria such as know-how, structure and process management, and multidisciplinarity.