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PubMed2005

The role of Cdc55 in the spindle checkpoint is through regulation of mitotic exit in Saccharomyces cerevisiae.

Cdc55, a B-type regulatory subunit of protein phosphatase 2A, has been implicated in mitotic spindle checkpoint activity and maintenance of sister chromatid cohesion during metaphase. The spindle checkpoint is composed of two independent pathways, one leading to inhibition of the metaphase-to-anaphase transition by checkpoint proteins, including Mad2, and the other to inhibition of mitotic exit by Bub2. We show that Cdc55 is a negative regulator of mitotic exit. A cdc55 mutant, like a bub2 mutant, prematurely releases Cdc14 phosphatase from the nucleolus during spindle checkpoint activation, and premature exit from mitosis indirectly leads to loss of sister chromatid cohesion and inviability in nocodazole. The role of Cdc55 is separable from Bub2 and inhibits release of Cdc14 through a mechanism independent of the known negative regulators of mitotic exit. Epistasis experiments indicate Cdc55 acts either downstream or independent of the mitotic exit network kinase Cdc15. Interestingly, the B-type cyclin Clb2 is partially stable during premature activation of mitotic exit in a cdc55 mutant, indicating mitotic exit is incomplete.

Cell Cycle Proteins↗
PubMed2006

The Ca2+-binding protein ALG-2 is recruited to endoplasmic reticulum exit sites by Sec31A and stabilizes the localization of Sec31A.

The formation of transport vesicles that bud from endoplasmic reticulum (ER) exit sites is dependent on the COPII coat made up of three components: the small GTPase Sar1, the Sec23/24 complex, and the Sec13/31 complex. Here, we provide evidence that apoptosis-linked gene 2 (ALG-2), a Ca(2+)-binding protein of unknown function, regulates the COPII function at ER exit sites in mammalian cells. ALG-2 bound to the Pro-rich region of Sec31A, a ubiquitously expressed mammalian orthologue of yeast Sec31, in a Ca(2+)-dependent manner and colocalized with Sec31A at ER exit sites. A Ca(2+) binding-deficient ALG-2 mutant, which did not bind Sec31A, lost the ability to localize to ER exit sites. Overexpression of the Pro-rich region of Sec31A or RNA interference-mediated Sec31A depletion also abolished the ALG-2 localization at these sites. In contrast, depletion of ALG-2 substantially reduced the level of Sec31A associated with the membrane at ER exit sites. Finally, treatment with a cell-permeable Ca(2+) chelator caused the mislocalization of ALG-2, which was accompanied by a reduced level of Sec31A at ER exit sites. We conclude that ALG-2 is recruited to ER exit sites via Ca(2+)-dependent interaction with Sec31A and in turn stabilizes the localization of Sec31A at these sites.

Apoptosis Regulatory Proteins↗
PubMed1998

Variations of the frontal exit of the supraorbital nerve: an anatomic study.

Until now, it has been taken for granted that the point of emergence of the supraorbital nerve is by way of a notch or a foramen at the border of the inner to the medial third of the supraorbital rim. In contrast to several anatomic textbooks, we noticed that the exit point was repeatedly not at the site where anticipated when implanting lid springs for facial palsy. This gave us the idea of investigating these variations and how big they are, because most open and recent endoscopic forehead lift techniques have relied on a constant exit point of the supraorbital nerve. A total of 507 macerated skulls (1014 orbits) from three anatomic collections in Austria and Germany were studied. All skulls were adult European skulls gathered from the prehistoric age up to the twentieth century. Additionally, 18 fixed cadavers (36 orbits) and 25 fresh cadavers (50 orbits) were studied. These data were not included in the statistical analysis but in the discussion. The anatomic measurements on the skulls were carried out with an anthropometric calliper. The examinations concentrated on the configuration (notch/foramen) and the number of exit point(s) on the supraorbital rim, the vertical distance from the supraorbital rim, and the distance from the nasion to the various exit point(s). Combining all of these parameters, 74 percent of the skulls showed asymmetric findings between the right and left orbits. In 15 percent of both orbits, the supraorbital nerve left the orbital cavity already in its two branches, the medial and lateral branch, either through a notch or a foramen, the foramen being sometimes the exit of a supraorbital canal. The average distance from the nasion to the frontal notch/foramen was 25 mm on both orbits (range 16 to 55 mm) and to the supraorbital notch/foramen 31 mm (range 20 to 49 mm). The largest vertical distance from the supraorbital rim to its farthest exit point was 19 mm. Other than what is cited in literature, the variations concerning the configuration and the distance of the exit point(s) of the supraorbital nerve were so significant that all forehead operations, especially those using endoscopic techniques, must take into account these findings.

Adult↗
PubMed2004

Ultrasonography in the management of exit site infections in peritoneal dialysis patients.

AIM: To assess the efficacy of using ultrasonography (USG) in monitoring the progress of exit site infection (ESI) in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). METHODS: Twenty-two cases of newly diagnosed ESI and 20 cases with normal exit sites as controls were assessed by using USG. The exit sites were reassessed by using USG after finishing a course of antibiotic therapy, and the sonographic findings were correlated with the clinical outcome. RESULTS: Out of the 22 cases of ESI, 21 cases had definite sonolucent zones around the external cuffs, while one case had normal sonographic findings. Of the 20 control cases of normal exit sites, 16 had normal sonographic findings, and four had sonolucent zones around the external cuffs. Exit site infections correlated with positive sonographic findings as compared to normal exits (P <0.0001). The 21 cases of ultrasonic-positive ESI were re-examined after antibiotic therapy, and 10 of these had a post-treatment sonolucent rim around the distal cuff < or =1 mm thick, while 11 cases were persistently > mm thick. The former group was shown to have a more favourable outcome (P=0.013). And despite variable USG findings, all eight patients with Pseudomonas aeruginosa-related ESI had an unfavourable clinical outcome. CONCLUSION: Ultrasonography of the exit sites in CAPD patients is a useful adjunctive tool in the management of ESI. A sonolucent zone around the external cuff >1 mm thick following a course of antibiotic treatment and the involvement of the proximal cuff are associated with poor clinical outcome. In ESI caused by Pseudomonas aeruginosa, the clinical outcome was uniformly poor irrespective of the sonographic findings.

Bacterial Infections↗
PubMed1999

The cholesterol requirement for sindbis virus entry and exit and characterization of a spike protein region involved in cholesterol dependence.

Semliki Forest virus (SFV) and Sindbis virus (SIN) are enveloped alphaviruses that enter cells via low-pH-triggered fusion in the endocytic pathway and exit by budding from the plasma membrane. Previous studies with cholesterol-depleted insect cells have shown that SFV requires cholesterol in the cell membrane for both virus fusion and efficient exit of progeny virus. An SFV mutant, srf-3, shows efficient fusion and exit in the absence of cholesterol due to a single point mutation in the E1 spike subunit, proline 226 to serine. We have here characterized the role of cholesterol in the entry and exit of SIN, an alphavirus quite distantly related to SFV. Growth, primary infection, fusion, and exit of SIN were all dramatically inhibited in cholesterol-depleted cells compared to control cells. Based on sequence differences within the E1 226 region between SFV, srf-3, and SIN, we constructed six SIN mutants with alterations within this region and characterized their cholesterol dependence. A SIN mutant, SGM, that had the srf-3 amino acid sequence from E1 position 224 to 235 showed increases of approximately 100-fold in infection and approximately 250-fold in fusion with cholesterol-depleted cells compared with infection and fusion of wild-type SIN. Pulse-chase analysis demonstrated that SGM exit from cholesterol-depleted cells was markedly more efficient than that of wild-type SIN. Thus, similar to SFV, SIN was cholesterol dependent for both virus entry and exit, and the cholesterol dependence of both steps could be modulated by sequences within the E1 226 region.

Aedes↗
PubMed2007

Amuchina 10% solution, safe antiseptic for preventing infections of exit-site of Tenckhoff catheters, in the pediatric population of a dialysis program.

Although, decreasing in incidence with the disconnection systems, the first complication is still peritonitis in patients with chronic renal failure and the second is infection of Tenckhoff catheter exit-site. All efforts made to diminish the frequency of exit-site infection lower the possibility of peritonitis. The pediatric population is well-known to have a major risk of infectious complications, and making easy and safe the care of the exit-site will prevent the peritonitis that follows. The aim of the study was to evaluate the efficacy of the Amuchina 10% solution vs. pH neutral soap in children with chronic renal failure, on preventing exit-site infection. There were 60 patients who were assigned randomly to one of two groups. One group used Amuchina 10% solution for the daily cleaning of the exit-site, and the other used pH neutral soap, with 14 months of follow-up. Before the study they have to be free of infection for at least 30 days. All were taught by the same nurse how to clean their exit-site. Groups were almost identical in years, sex, and time on dialysis. We had nine infections in the soap group and none in the Amuchina 10% solution group, with an OR: 17 (p = 0.004). From these nine infections, the bacteria isolated were: 4 (13%) were caused by Pseudomona aeruginosa, 1 (3.3%) by Staphylococcus aureus, coagulase-positive staphylococci in 2 (6.6%) and Serratia marcensens in 1 (3.3%). In conclusion, Amuchina 10% solution is effective in preventing infection on the exit-site, without any secondary topical reaction.

Adolescent↗
PubMed2004

Active and specific recruitment of a soluble cargo protein for endoplasmic reticulum exit in the absence of functional COPII component Sec24p.

Exit of proteins from the yeast endoplasmic reticulum (ER) is thought to occur in vesicles coated by four proteins, Sec13p, Sec31p, Sec23p and Sec24p, which assemble at ER exit sites to form the COPII coat. Sec13p may serve a structural function, whereas Sec24p has been suggested to operate in selection of cargo proteins into COPII vesicles. We showed recently that the soluble glycoprotein Hsp150 exited the ER in the absence of Sec13p function. Here we show that its ER exit did not require functional Sec24p. Hsp150 was secreted to the medium in a sec24-1 mutant at restrictive temperature 37 degrees C, while cell wall invertase and vacuolar carboxypeptidase Y remained in the ER. The determinant guiding Hsp150 to this transport route was mapped to the C-terminal domain of 114 amino acids by deletion analysis, and by an HRP fusion protein-based EM technology adapted here for yeast. This domain actively mediated ER exit of Sec24p-dependent invertase in the absence of Sec24p function. However, the domain was entirely dispensable for ER exit when Sec24p was functional. The Sec24p homolog Sfb2p was shown not to compensate for nonfunctional Sec24p in ER exit of Hsp150. Our data show that a soluble cargo protein, Hsp150, is selected actively and specifically to budding sites lacking normal Sec24p by a signature residing in its C-terminal domain.

Endoplasmic Reticulum↗
PubMed2002

Keeping the catheter exit site clean by sealing with a dressing film in patients under continuous ambulatory peritoneal dialysis.

In patients on continuous ambulatory peritoneal dialysis (CAPD), exit-site care is troublesome. We developed a new method for exit-site care, using a dressing film. We investigated the possibility of keeping the exit site clean for up to 6 weeks, using seven protocols: Control group (n = 24)--the exit site was cleaned with a povidone iodine solution daily and a gauze dressing was applied. Group A (n = 120)--the exit site was cleaned with a povidone iodine solution once weekly, was covered with a small piece of gauze, and was completely sealed using a dressing film. Group B (n = 181)--as with Group A, except once every 2 weeks. Group C (n = 64)--as with Group A, except once every 3 weeks. And so on: Group D (n = 45)--once every 4 weeks. Group E (n = 8)--once every 5 weeks. Group F (n = 2)--once every 6 weeks. At each session, we examined the small gauze bacteriologically. In groups A-F, the patients were asked to bathe every day and not to do anything about the exit site for 1-6 weeks, as applicable. In the control group, the rate of positive bacterial culture was 87.5%. In the other groups, the rates were group A, 15%; group B, 6.6%; group C, 6.3%; group D, 2.2%; and groups E and F, 0%. In the film-method groups, the rates of positive bacterial culture were significantly low. We thought that the film method kept the exit site clean.

Aged↗
PubMed1992

Comparison of exit-site infections in disconnect versus nondisconnect systems for peritoneal dialysis.

OBJECTIVE: To determine if disconnect systems reduce the incidence of exit-site infections when compared to nondisconnect systems. DESIGN: We prospectively monitored exit-site infections and peritonitis rates in 96 disconnect patients (Y-set, automated peritoneal dialysis (APD)) and 60 nondisconnect patients (spike, ultraviolet connection device (UVXD)). SETTING: A freestanding chronic peritoneal dialysis unit staffed by physicians from both a medical school and a private setting. PATIENTS: All patients who began peritoneal dialysis at our unit were monitored, regardless of cause of end-stage renal disease (ESRD) or age. INTERVENTION: Patients were dialyzed using the system (Y-set, spike, etc.) most appropriate for their life-style and their ability to administer self-care. MAIN OUTCOME: We attempted to follow disconnect and nondisconnect patients for a similar median time on dialysis and compared differences in exit-site infections. RESULTS: Peritonitis rates (episodes/pt year) were reduced for disconnect (0.60) versus nondisconnect (0.99) systems (p = 0.0006). Despite the marked reduction in peritonitis rates, there was no difference in exit-site infection rates (0.35 vs 0.38), the time to the first exit-site infection, or the time to the first catheter removal for disconnect versus nondisconnect groups. When individual systems were compared, differences in exit-site infection rates (episodes/pt years) were noted (0.62,spike; 0.26,UVXD; 0.32,Y-set; 0.41,APD). CONCLUSION: We found no overall difference in exit-site infection rates for disconnect versus nondisconnect systems, despite a reduction in peritonitis rates for disconnect systems.

Adult↗
PubMed2004

[Effect of progesterone on theophylline and prolactin stimulated Ca2+ exit from intracellular stores of pig oocytes].

Effect of progesterone on theophylline and prolactin stimulated Ca2+ exit from intracellular stores of pig oocytes was investigated using a fluorescent dye chlortetracycline. It is shown that in progesterone treated oocytes prolactin in concentration 50 ng/ml inhibits Ca2+ exit from intracellular stores of pig oocytes. Theophylline exerts the effect on prolactin Ca2+ exit from intracellular stores of pig oocytes. Employment of protein kinase C inhibitor cancelled inhibitory effect of prolactin and theophylline on Ca2+ exit from intracellular stores of pig oocytes. Ca2+ exit from intracellular stores of pig oocytes caused a joint influence of prolactin and GDP, and that of theophylline and GTP. The influence of protein kinase C inhibitor cancelled the stimulating effect of prolactin and GDP on Ca2+ exit from intracellular stores of pig oocytes also did not render any influence on the action of theophylline and GTP. These data suggest the influence of progesterone on theophylline and prolactin stimulated Ca2+ exit from intracellular stores of pig oocytes.

Animals↗
PubMed1989

Exit-site location does not influence peritoneal catheter infection rate.

Peritoneal catheter infections are a cause of peritonitis, catheter loss, and permanent transfer of continuous ambulatory peritoneal dialysis (CAPD) patients to hemodialysis. Risk factors for catheter infections have not been delineated. We investigated the location of the peritoneal exit-site location as a risk factor for catheter infection and loss. There was no relationship between catheter infection rates and exit location. Catheters exiting on the beltline had a median infection rate of 0.5 episodes/year, as opposed to 1.2 episodes/year for catheters exiting above the beltline and 0.9 episodes/year for catheters exiting below the beltline (ns). The percentage of catheters that became infected and required removal was the same for catheters exiting above, below, or on the beltline. Although we recommend avoiding the beltline for patient comfort, exit-site location is not an important determinant of infection rates or catheter outcome.

Catheters, Indwelling↗
PubMed1976

Glycine transport by hemolysed and restored pigeon red cells. Effects of a Donnan-induced electrical potential on entry and exit kinetics.

The influence of a Donnan effect on the transport of glycine by hemolysed and restored pigeon red cells was examined. The Donnan effect was produced by replacing Cl- with 2,4-toluenedisulfonate or glutamate. The effects of the associated membrane potential and inside-outside pH difference on glycine entry and exit rates were examined. The effects of pH on entry and exit rates in the absence of a Donnan effect were also examined. In the absence of a Donnan effect, Na+-dependent glycine entry requires the protonated form of a group with a pKapp of 7.9 and the deprotonated form of another group with a pKapp of 6.8. Neither of these are required for exit but the deprotonated form of a group(s) with a pKapp of 6.2 is required. The pK 7.9 group and pK 6.2 group probably react with H+ at the inner face of the membrane and the pK 6.8 group probably reacts at the outer face. The V for glycine entry was determined for cells with their Cl- largely replaced by toluenedisulfonate and without such replacement. Between pH 6.1 and 7, the ratio of the respective V values, VT/VC1, was 1.5-1.7. VT/VC1 rose above pH 7 to near 4 at pH 8.3. At pH 6.9, with glutamate replacing cell Cl-, the analogous ratio (VGlu/VC1) was 1.7. The increase of VT/VC1 above pH 7 could be quantitatively accounted for by the increase in cell [H+]/medium [H+] caused by the Donnan effect together with the assumption that the pK 7.9 group reacts with H+ at the inner face of the membrane. When cell Cl- was replaced by toluenedisulfonate or glutamate there was a drop in the term in the glycine Km describing Na+ dependence of glycine entry. When cell Cl- was replaced by toluenedisulfonate therewas a rise in the Na+-independent term in the glycine entry Km. By replacing varying amounts of cell Cl- with either toluenedisulfonate or glutamate, plots were obtained of entry rates vs. the cell [Cl-]/ medium [Cl-] ratio consistent with the assumption that the Donnan-induced membrane potential acts on a "moving" charge. Glycine exit was only slightly accelerated by trans-toluenedisulfonate. The ratio, exit rate into toluenedisulfonate medium/exit rate into Cl- medium rose with decreasing pH. This rise could be accounted for by a Donnan-induced inside-outside pH difference which affects a pKapp 6.2 group reacting with internal H+. The observed influences of the Donnan effect on V (glycine entry), on both components of Km (glycine entry), on the shape of the plot of glycine entry rate vs. the cell [Cl-]/medium [Cl-] ratio and on glycine exit all fit the assumptions that when the empty porter reorients, one unit of negative charge accompanies it "across" the membrane and that no other steps involve charge movement. The properties of the system seem inconsistent with a translational ("ferry boat") mobile carrier.

Animals↗
PubMed1988

Specific recognition of the 3'-terminal adenosine of tRNAPhe in the exit site of Escherichia coli ribosomes.

Ribosomes from Escherichia coli possess, in addition to A and P sites, a third tRNA binding site, which according to its presumed function in tRNA release during translocation has been termed the exit site. The exit site exhibits a remarkable specificity for deacylated tRNA; charged tRNA, e.g. N-AcPhe-tRNAPhe, is not bound significantly. To determine the molecular basis of this discrimination, we have measured the exit site binding affinities of a number of derivatives of tRNAPhe from E. coli, modified at the 3' end. Binding to the exit site of the tRNAPhe derivatives was measured fluorimetrically by competition with a fluorescent tRNAPhe derivative. We show here that removal of the 2' and 3' hydroxyl groups of the 3'-terminal adenosine decreases the affinity of tRNAPhe for the exit site 15 and 40-fold, respectively. Substitutions at the 3' hydroxyl group (aminoacylation, phosphorylation, cytidylation) as well as removal of the 3'-terminal adenosine (or adenylate) of tRNAPhe lower the affinity below the detection limit of 2 x 10(5) M-1, i.e. more than 100-fold. Modification of the adenine moiety (1,N6-etheno adenine) or replacement of it with other bases (cytosine, guanine) has the same dramatic effect. In contrast, the binding to both P and A sites is virtually unaffected by all of the modifications tested. These results suggest that a major fraction (at least -12 kJ/mol, probably about -17 kJ/mol) of the free energy of exit site binding of tRNAPhe (-42 kJ/mol at 20 mM-Mg2+) is contributed by the binding of the 3'-terminal adenine to the ribosome. The binding most likely entails the formation of hydrogen bonds.

Adenosine↗
PubMed1995

The use of an electronic portal imaging device for exit dosimetry and quality control measurements.

PURPOSE: To determine ways in which electronic portal imaging devices (EPIDs) could be used to (a) measure exit doses for external beam radiotherapy and (b) perform quality control checks on linear accelerators. METHODS AND MATERIALS: When imaging, our fluoroscopic EPID adjusts the gain, offset, and frame acquisition time of the charge coupled device (CCD) camera automatically, to allow for the range of photon transmissions through the patient, and to optimize the signal-to-noise ratio. However, our EPID can be programmed to act as an integrating dosemeter. EPID dosemeter measurements were made for 20 MV photons, for different field sizes and thicknesses of unit density phantom material placed at varying exit surface to detector distances. These were compared with simultaneous Silicon diode exit dose measurements. Our exit dosimetry technique was verified using an anthropomorphic type phantom, and some initial measurements have been made for patients treated with irregularly shaped 20 MV x-ray fields. In this dosimetry mode, our EPID was also used to measure certain quality control parameters, x-ray field flatness, and the verification of segmented intensity modulated field prescriptions. RESULTS: Configured for dosimetry, our EPID exhibited a highly linear response, capable of resolving individual monitor units. Exit doses could be measured to within about 3% of that measured using Silicon diodes. Field flatness was determined to within 1.5% of Farmer dosemeter measurements. Segmented intensity modulated fields can be easily verified. CONCLUSIONS: Our EPID has the versatility to assess a range of parameters pertinent to the delivery of high quality, high precision radiotherapy. When configured appropriately, it can measure exit doses in vivo, with reasonable accuracy, perform certain quick quality control checks, and analyze segmented intensity modulated treatment fields.

Humans↗
PubMed1989

Ultrasound as a tool in the diagnosis and management of exit-site infections in patients undergoing continuous ambulatory peritoneal dialysis.

Ultrasonographic examination of the subcutaneous course and exit site of the Tenckhoff catheter in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) was performed to evaluate catheter-related infections. Real-time ultrasound studies were performed in 24 patients with initial exit-site infections; clinically suspected tunnel infections were excluded from analysis. A peri-catheter sonolucent fluid collection, considered a positive study, was demonstrated in 13 ultrasound examinations and tended to be organism-specific; eight of 12 Staphylococcus aureus exit-site infections and three of four gram-negative exit-site infections had positive studies. Only two of seven Staphylococcus epidermidis exit-site infections were initially positive on ultrasound examination. Nine of 13 patients with positive ultrasound studies ultimately lost their catheters to infection despite weeks of parenteral antibiotic therapy and local incision and drainage. There were 11 negative ultrasound studies. Only one of these patients' catheters was lost because of infection. In some episodes of CAPD-associated exit-site infections, especially those caused by S aureus and gram-negative organisms, ultrasound examination of the catheter course may be useful to diagnose unsuspected tunnel infections, direct early therapy, and confirm resolution or persistence of the infections.

Catheters, Indwelling↗
PubMed1998

Effect of a silver device in preventing catheter-related infections in peritoneal dialysis patients: silver ring prophylaxis at the catheter exit study.

Catheter-related infections remain a significant cause of method failure in chronic peritoneal dialysis (PD) therapy. Given the increasing antibiotic resistance, such nonpharmacological strategies as local silver devices attract more interest. To establish whether a silver ring device (designed by Grosse-Siestrup in 1992) mounted onto the PD catheter and placed at the exit site at skin level is effective in preventing exit-site and other catheter-related infections, a prospective 12-month, multicenter, controlled study stratified by diabetes status was conducted. The study subjects were assessed by an extensive structured inventory, including a broad spectrum of control variables, such as age, body mass index (BMI), Staphylococcus aureus carrier status, catheter features, mode and quality of PD therapy, comorbidity, and psychosocial rehabilitation. Ten experienced German outpatient dialysis centers (seven adult, three pediatric) participated in the trial. All eligible patients (n=195) from the study area without catheter-related infections during the ascertainment period were included (incidental subjects undergoing PD therapy for at least 3 months). The main outcome measures were the occurrence of first exit-site infections (primary study end point), sinus tract/tunnel infection, and peritonitis. Ninety-seven patients were assigned to the silver ring and 98 patients to the control group. Baseline characteristics of age, sex, proportion of pediatric and incidental patients, S aureus carrier status, and other variables were similar in both groups. The incidence of infections in the silver ring group versus the control group was as follows: 23 of 97 versus 16 of 98 patients had exit-site infections, 12 of 97 versus 12 of 98 patients had sinus tract/tunnel infections, 16 of 97 versus 18 of 98 patients had peritonitis, respectively. Kaplan-Meier analysis for the probability of an infection-free interval showed no statistical difference (log-rank test) between the two groups. Displacement of the silver ring contributed to study termination in 6% of the study group patients, including two patients with catheter loss. Univariate analysis and multiple logistic regression identified younger age (<50 years), low serum albumin level (<35 g/L), number of previously placed PD catheters, short cuff-exit distance (<2 cm), and S aureus nasal carriage as risk factors for the development of exit-site infections. In conclusion, our study does not show any benefit of the silver ring in preventing catheter-related infections in PD patients. Thus, prevention of infection-related method failure in PD still has to rely on conventional antibiotic treatment strategies and less so on alternative methods.

Adult↗
PubMed2001

Pace mapping of postinfarction scar to detect ventricular tachycardia exit sites and zones of slow conduction.

INTRODUCTION: The exit site and central common pathway of slow conduction are preferred sites to guide radiofrequency ablation of postinfarction ventricular tachycardia (VT). Both require inducibility of VT. In addition, their low amplitude hampers direct recording of potentials generated by activation in pathways of slow conduction. We hypothesized that pace mapping during sinus rhythm would help to detect the VT exit site and potentials generated by activation in pathways of slow activation. METHODS AND RESULTS: In 13 patients suffering from VT late after anterior (n = 10) or inferior (n = 3) myocardial infarction, stimulation was performed in scarred endocardium at 23.5 (range 13 to 36) sites per patient during arrhythmia surgery. Multielectrode recordings (64 sites) during stimulation at a fixed cycle length of 500 msec were obtained. Endocardial breakthrough sites distant (>2 cm) from the pacing site were found at 4.3 (range 3 to 19) pacing sites per patient. Low-amplitude discrete potentials (LADPs) could be detected between the pacing site and the breakthrough site in 2.3 (range 0 to 13) of 4.3 stimulation sequences. In these patients, 19 VTs were induced and the exit site determined. In 6 patients, the distant pacing breakthrough site was identical to the VT exit site; in 7 patients, no similar exit sites were found. LADPs during VT were found at a median 2.0 (range 0 to 14) sites per patient. CONCLUSION: Pace mapping of the postinfarction endocardial scar during sinus rhythm revealed 50% of the endocardial exit sites of VT and the same number of LADPs observed during VT.

Cardiac Pacing, Artificial↗
PubMed2002

Utility of exit block for identifying electrical isolation of the pulmonary veins.

INTRODUCTION: Electrical isolation of the pulmonary veins (PVs) to treat paroxysmal atrial fibrillation (AF) has been described using "entry block" as an endpoint for PV isolation. We describe a new technique for guiding PV isolation, using "exit block" out of the PV after ablation as a criterion for successful isolation. METHODS AND RESULTS: A circular mapping catheter was positioned at the os of arrhythmogenic PVs and ablation was performed proximal to the mapping catheter until entry block into the vein was achieved. Pacing was performed from the mapping catheter and from the ablator inside the PV to document exit block out of the PV. In patients in whom cardioversion did not restore sinus rhythm, PV isolation was performed in AF. Entry and exit block were reassessed in ablated veins after a 20-minute waiting period. Ninety-five PVs were ablated in 41 patients. A total of 66 PVs in 34 patients were ablated in sinus rhythm. After entry block was achieved, exit block was present in only 38 (58%) of 66 PVs. A total of 29 PVs in 21 patients were ablated in AF. After cardioversion to sinus rhythm, there was evidence of entry block into the PV in 20 (69%) of 29 PVs and exit block in only 14 (48%) of 29 PVs. There was no significant difference between the total number of lesions applied per vein in sinus rhythm compared with AF (11.6 +/- 8.6 vs 10.3 +/- 6.2; P = NS). There was recovery of conduction after a 20-minute waiting period in 9 (11%) of 84 PVs. CONCLUSION: Identification of exit block after ostial PV ablation provides a clear endpoint for electrical isolation of the PVs. Isolation of the PVs can be performed during sustained AF without the need to apply excess RF lesions. Applying a 20-minute waiting period after electrical isolation will identify reconnection in approximately 10% of PVs.

Adult↗