Distal dendrites of frog motor neurons: a computer-aided electron microscopic study of cobalt-filled cells.

With the aid of the cobalt labelling technique, frog spinal cord motor neuron dendrites of the subpial dendritic plexus have been identified in serial electron micrographs. Computer reconstructions of various lengths (2.5-9.8 micron) of dendritic segments showed the contours of these dendrites to be highly irregular, and to present many thorn-like projections 0.4-1.8 micron long. Number, size and distribution of synaptic contacts were also determined. Almost half of the synapses occurred at the origins of the thorns and these synapses had the largest contact areas. Only 8 out of 54 synapses analysed were found on thorns and these were the smallest. For the total length of reconstructed dendrites there was, on average, one synapse per 1.2 micron, while 4.4% of the total dendritic surface was covered with synaptic contacts. The functional significance of these distal dendrites and their capacity to influence the soma membrane potential is discussed.

Persistence of a Gastrocutaneous Fistula after gastrostomy removal in children: Incidence and predictive factors

Background/Purpose: The aims of this study were to determine the incidence of persistent gastrocutaneous fistulas (GCF) after gastrostomy removal and to identify associated risk factors. Methods: This retrospective study included 75 children from the Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland who had a gastrostomy performed between 1988 and 2010. The records of the children were reviewed for sex, age at the time of gastrostomy removal, underlying disease, type of gastrostomy placement and length of use, and then analyzed in order to find a correlation between the GCF and these parameters. Results: The gastrostomy orifice did not close spontaneously within the first month in 33 of the patients (44%), and 15 subsequently underwent surgical closure. The mean duration of gastrostomy use was significantly longer in children who developed a persistent GCF (30 vs. 19 months, P = 0.03). The other parameters studied did not show any significant association with the persistence of a GCF. Conclusions: The only predictive factor determining the persistence of a GCF was found to be the timespan between the placement and removal of the gastrostomy appliance. Elective surgical closure of the gastrostomy orifice should be considered after 1 month of persistent GCF.

Successful therapy for a patient with an infected ascending aortic graft and sternal osteomyelitis without graft removal.

Objective: Following open-heart surgery, sternal osteomyelitis or infection of the graft may be a serious complication with high mortality rates. The recommended treatment of an infected graft is its explantation. Because of the poor performance status of the patient, this may not always be an option. We report a successful treatment concept without removal of the infected graft. Methods: The infected ascending aortic graft and the remaining sternum of a critically ill 60-year-old man were covered with a bilateral pectoralis muscle flap. Results: Postoperatively, the laboratory test values normalized and the patient was discharged 1 month after the intervention. One year after surgery, the patient was in good condition and the examination showed no signs of infection. Conclusion: The thus demonstrated treatment concept with insertion of well-vascularized tissues in combination with a specific antibiotic regime in our hands proved to be an additional option for the successful management of life-threatening infections of a sternal osteomyelitis in combination of an infected aortic graft.

Antibiotic lock technique combined with systemic antimicrobial therapy for management of port-related bloodstream infections in onco-haematological patients without catheter removal

Background : Port-related bloodstream infection (PRBSI) is a common complication associated with long-term use of ports systems. Systemic antimicrobial therapy (ST) and removal of the device is the standard management of PRBSI. However, a conservative management combining ST with antibiotic lock therapy (ALT) without port removal has been suggested as an alternative management option for infections due to gram-positive skin colonizers with low virulence.¦Objectives : i) to assess the frequency of management of PRBSI in onco-hematological patients by combining the ALT with ST, without catheter removal and ii) to analyze the efficacy of such an approach.¦Methods : Retrospective observational study over a 6-year period between 2005 and 2010, including patients who where diagnosed with PRBSI and who were treated with ST and ALT. PRBSI diagnosis consisted in clinical signs of bacteremia with blood cultures positive for gram-positive skin colonizers. The primary endpoint was failure to cure the PRBSI.¦Results : 61 port infections were analysed, of which 23 PRBSI met the inclusion criteria. All the patients were suffering from haematological conditions and 75% were neutropenic at the time of PRBSI diagnosis. S. epidermidis was responsible for 91% of PRBSI (21/23). The median duration of ST was 14 days (range 7-35) and the median duration of ALT was 15 days (range 8-41). Failure to cure the PRBSI requiring port removal was observed in 4 patients, but was not associated with severe infectious complications. Kaplan-Meier analysis showed a success rate in port salvage at day 180 (6 months) of 78% (95%CI 59-97%).¦Conclusion : The success rate observed in the present study suggests that combining ST and ALT is an effective option to conservatively treat PRBSI caused by pathogens of low virulence such as S. epidermidis.

Late removal of retrievable caval filters.

The advent of retrievable caval filters was a game changer in the sense, that the previously irreversible act of implanting a medical device into the main venous blood stream of the body requiring careful evaluation of the pros and cons prior to execution suddenly became a "reversible" procedure where potential hazards in the late future of the patient lost most of their weight at the time of decision making. This review was designed to assess the rate of success with late retrieval of so called retrievable caval filters in order to get some indication about reasonable implant duration with respect to relatively "easy" implant removal with conventional means, i.e., catheters, hooks and lassos. A PubMed search (www.pubmed.gov) was performed with the search term "cava filter retrieval after 30 days clinical", and 20 reports between 1994 and 2013 dealing with late retrieval of caval filters were identified, covering approximately 7,000 devices with 600 removed filters. The maximal duration of implant reported is 2,599 days and the maximal implant duration of removed filters is also 2,599 days. The maximal duration reported with standard retrieval techniques, i.e., catheter, hook and/or lasso, is 475 days, whereas for the retrievals after this period more sophisticated techniques including lasers, etc. were required. The maximal implant duration for series with 100% retrieval accounts for 84 days, which is equivalent to 12 weeks or almost 3 months. We conclude that retrievable caval filters often become permanent despite the initial decision of temporary use. However, such "forgotten" retrievable devices can still be removed with a great chance of success up to three months after implantation. Conventional percutaneous removal techniques may be sufficient up to sixteen months after implantation whereas more sophisticated catheter techniques have been shown to be successful up to 83 months or more than seven years of implant duration. Tilting, migrating, or misplaced devices should be removed early on, and replaced if indicated with a device which is both, efficient and retrievable.

Purification of recombinant proteins by chemical removal of the affinity tag.

The efficient removal of a N- or C-terminal purification tag from a fusion protein is necessary to obtain a protein in a pure and active form, ready for use in human or animal medicine. Current techniques based on enzymatic cleavage are expensive and result in the presence of additional amino acids at either end of the proteins, as well as contaminating proteases in the preparation. Here we evaluate an alternative method to the one-step affinity/protease purification process for large-scale purification. It is based upon the cyanogen bromide (CNBr) cleavage at a single methionine placed in between a histidine tag and a Plasmodium falciparum antigen. The C-terminal segment of the circumsporozoite polypeptide was expressed as a fusion protein with a histidine tag in Escherichia coli purified by Ni-NAT agarose column chromatography and subsequently cleaved by CNBr to obtain a polypeptide without any extraneous amino acids derived from the cleavage site or from the affinity purification tag. Thus, a recombinant protein is produced without the need for further purification, demonstrating that CNBr cleavage is a precise, efficient, and low-cost alternative to enzymatic digestion, and can be applied to large-scale preparations of recombinant proteins.

Development and use of a high-fidelity simulator for fetal endotracheal balloon occlusion (FETO) insertion and removal.

Objectives The objective of this article is to describe the development of an anatomically accurate simulator in order to aid the training of a perinatal team in the insertion and removal of a fetal endoscopic tracheal occlusion (FETO) balloon in the management of prenatally diagnosed congenital diaphragmatic hernia. Methods An experienced perinatal team collaborated with a medical sculptor to design a fetal model for the FETO procedure. Measurements derived from 28-week fetal magnetic resonance imaging were used in the development of an anatomically precise simulated airway within a silicone rubber preterm fetal model. Clinician feedback was then used to guide multiple iterations of the model with serial improvements in the anatomic accuracy of the simulator airway. Results An appropriately sized preterm fetal mannequin with a high-fidelity airway was developed. The team used this model to develop surgical skills with balloon insertion, and removal, and to prepare the team for an integrated response to unanticipated delivery with the FETO balloon still in situ. Conclusions This fetal mannequin aided in the ability of a fetal therapy unit to offer the FETO procedure at their center for the first time. This model may be of benefit to other perinatal centers planning to offer this procedure.

Synapses on motoneuron dendrites in the brachial section of the frog spinal cord: a computer-aided electron microscopic study of cobalt-filled cells.

Cobalt-labelled motoneuron dendrites of the frog spinal cord at the level of the second spinal nerve were photographed in the electron microscope from long series of ultrathin sections. Three-dimensional computer reconstructions of 120 dendrite segments were analysed. The samples were taken from two locations: proximal to cell body and distal, as defined in a transverse plane of the spinal cord. The dendrites showed highly irregular outlines with many 1-2 microns-long 'thorns' (on average 8.5 thorns per 100 microns 2 of dendritic area). Taken together, the reconstructed dendrite segments from the proximal sites had a total length of about 250 microns; those from the distal locations, 180 microns. On all segments together there were 699 synapses. Nine percent of the synapses were on thorns, and many more close to their base on the dendritic shaft. The synapses were classified in four groups. One third of the synapses were asymmetric with spherical vesicles; one half were symmetric with spherical vesicles; and one tenth were symmetric with flattened vesicles. A fourth, small class of asymmetric synapses had dense-core vesicles. The area of the active zones was large for the asymmetric synapses (median value 0.20 microns 2), and small for the symmetric ones (median value 0.10 microns 2), and the difference was significant. On average, the areas of the active zones of the synapses on thin dendrites were larger than those of synapses on large calibre dendrites. About every 4 microns 2 of dendritic area received one contact. There was a significant difference between the areas of the active zones of the synapses at the two locations. Moreover, the number per unit dendritic length was correlated with dendrite calibre. On average, the active zones covered more than 4% of the dendritic area; this value for thin dendrites was about twice as large as that of large calibre dendrites. We suggest that the larger active zones and the larger synaptic coverage of the thin dendrites compensate for the longer electrotonic distance of these synapses from the soma.

Identification and removal of low-complexity sites in allele-specific analysis of ChIP-seq data.

MOTIVATION: High-throughput sequencing technologies enable the genome-wide analysis of the impact of genetic variation on molecular phenotypes at unprecedented resolution. However, although powerful, these technologies can also introduce unexpected artifacts. Results: We investigated the impact of library amplification bias on the identification of allele-specific (AS) molecular events from high-throughput sequencing data derived from chromatin immunoprecipitation assays (ChIP-seq). Putative AS DNA binding activity for RNA polymerase II was determined using ChIP-seq data derived from lymphoblastoid cell lines of two parent-daughter trios. We found that, at high-sequencing depth, many significant AS binding sites suffered from an amplification bias, as evidenced by a larger number of clonal reads representing one of the two alleles. To alleviate this bias, we devised an amplification bias detection strategy, which filters out sites with low read complexity and sites featuring a significant excess of clonal reads. This method will be useful for AS analyses involving ChIP-seq and other functional sequencing assays.

Recovery of biological motion perception and network plasticity after cerebellar tumor removal.

Visual perception of body motion is vital for everyday activities such as social interaction, motor learning or car driving. Tumors to the left lateral cerebellum impair visual perception of body motion. However, compensatory potential after cerebellar damage and underlying neural mechanisms remain unknown. In the present study, visual sensitivity to point-light body motion was psychophysically assessed in patient SL with dysplastic gangliocytoma (Lhermitte-Duclos disease) to the left cerebellum before and after neurosurgery, and in a group of healthy matched controls. Brain activity during processing of body motion was assessed by functional magnetic resonance imaging (MRI). Alterations in underlying cerebro-cerebellar circuitry were studied by psychophysiological interaction (PPI) analysis. Visual sensitivity to body motion in patient SL before neurosurgery was substantially lower than in controls, with significant improvement after neurosurgery. Functional MRI in patient SL revealed a similar pattern of cerebellar activation during biological motion processing as in healthy participants, but located more medially, in the left cerebellar lobules III and IX. As in normalcy, PPI analysis showed cerebellar communication with a region in the superior temporal sulcus, but located more anteriorly. The findings demonstrate a potential for recovery of visual body motion processing after cerebellar damage, likely mediated by topographic shifts within the corresponding cerebro-cerebellar circuitry induced by cerebellar reorganization. The outcome is of importance for further understanding of cerebellar plasticity and neural circuits underpinning visual social cognition.