Ventricular rate smoothing for atrial fibrillation: a quantitative comparison study.

AIMS: To quantitatively compare the ventricular rate-smoothing (VRS) effects of different ventricular pacing (VP) protocols for atrial fibrillation (AF). METHODS AND RESULTS: Using a recently developed open-source model that can simulate the ventricular response in AF and VP, the performance of fixed-rate pacing and four previously published VRS algorithms were assessed by the mean RR (mRR), the root mean square of successive RR differences (RMSSD), the percentage of ventricular senses (VS%), and the percentage of short RR intervals (sRR%). All pacing protocols cause rate-dependent reduction of RMSSD, VS%, and sRR% with or without shortening of mRR compared to spontaneous AF. Fixed-rate pacing was more sensitive to the intrinsic rate than the VRS algorithms. The performance was generally comparable between different VRS algorithms, although higher mRR and VS% can be achieved at the expense of larger RMSSD and sRR%. CONCLUSION: The effect of VP on ventricular rhythm in AF depends on both intrinsic rate and the aggressiveness of the pacing protocol. Adequate rate control is necessary for effective operation of the VRS algorithm. Choosing VRS algorithm should balance between the beneficial effects of rate regularization and the negative effects of increasing heart rate and percentage of VP.     

Sentinel Bleeding After Pancreaticoduodenectomy: A Disregarded Sign

Introduction Delayed massive hemorrhage induced by pancreatic fistula after pancreaticoduodenectomy is a rare but life-threatening complication. The purpose of this study was to analyze the clinical course of patients with late hemorrhage, with or without sentinel bleeding, to better define treatment options in the future. Material and Methods From April 1998 to December 2006, 189 pancreaticoduodenectomies were performed. Eleven patients, including two patients referred from other hospitals, were treated with delayed massive hemorrhage occurring 5 days or more after pancreaticoduodenectomy. Sentinel bleeding was defined as minor blood loss via surgical drains or the gastrointestinal tract with an asymptomatic interval until development of hemorrhagic shock. The clinical data of patients with bleeding episodes were analyzed retrospectively. Results Eight of the 11 patients had sentinel bleeding, and seven of them had it at least 6 h before acute deterioration. Seven out of 11 patients died, five out of eight with sentinel bleeding. No differences could be detected between patients with or without sentinel bleeding before delayed massive hemorrhage. The only difference found was that non-surviving patients were significantly older than surviving patients. Delayed massive hemorrhage is a common cause of death after pancreaticoduodenostomy complicated by pancreatic fistula formation. The observation of sentinel bleeding should lead to emergency angiography and dependent from the result to emergency relaparotomy to increase the likelihood of survival.     

Atypical absences and recurrent absence status in an adult with Angelman syndrome due to the UBE3A mutation.

Angelman syndrome is a neurogenetic disorder resulting in refractory epilepsy and profound psychomotor retardation in its most prevalent form, caused by deletion of maternal chromosome 15q11-13. We report the case of a 29-year-old, mentally retarded man with unusual electroencephalographic changes during periods of atypical absence status epilepticus, a previously unreported manifestation of the usually milder, drug-responsive epilepsy associated with Angelman syndrome due to the UBE3A mutation.[Published with video sequences].     

Voraussetzungen der ICD-Implantation Ist eine elektrophysiologische Untersuchung heute noch unumg?nglich?

Elektrophysiologische Untersuchungen (EPU) und programmierte Ventrikelstimulationen (PVS) werden vor der Implantation eines Defibrillators (ICD) empfohlen, wenn Patienten ohne nachweisbare strukturelle Herzerkrankung oder mit hypertrophischer obstruktiver Kardiomyopathie (HOCM) einen Herzstillstand überlebt haben, weil die Prävalenz von prinzipiell kurierbaren Rhythmusstörungen wie idiopathischen ventrikulären Tachykardien (VT), bei diesen Patienten hoch ist. Gleiches gilt für Patienten nach überlebtem Herzstillstand mit einer kurzen PQ-Zeit oder einer Deltawelle. Patienten mit Tachykardien, bei denen die Diagnose VT unsicher ist, sollten ebenfalls einer EPU unterzogen werden. Wenn sich Patienten mit nicht anhaltenden Tachykardien oder Synkopen vorstellen, sind eine EPU und PVS zur Risikostratifizierung indiziert. Bei den übrigen Patienten mit eingeschränkter linksventrikulärer Pumpfunktion nach überlebtem Herzstillstand oder instabiler VT, die Kandidaten für eine ICD-Implantation sind, haben die EPU und PVS möglicherweise nur einen geringen Nutzen.     

Reconstruction of lateral skull base defects after tumor ablation.

Neoplasms located in the lateral skull base region present a challenge for evaluation and management due to their difficult anatomic location and the complex reconstruction that is required following extensive tumor resection. Repair following tumor ablation requires a watertight dural seal, obliteration of the dead space, and coverage with vascularized soft tissue. Advances in radiologic imaging, diagnostic pathology, and surgical techniques and a multidisciplinary team for tumor ablation and reconstruction have significantly improved the treatment of these patients, minimized the occurrence of postoperative complications, and maximized patient outcome and quality of life. In this article, we present our experience in the reconstruction of extensive lateral skull base defects after tumor ablation.     

Unaltered immunoglobulin expression in hybridoma cells modified by targeting of the heavy chain locus with an integration vector.

Chimeric antibodies against the murine T-cell antigen Thy-1.2 were generated in amounts sufficient for in vivo studies by substituting the constant gene segments via homologous recombination in the hybridoma cell. We show that an integration vector targets the heavy chain locus at high frequency even in a non-isogenic situation. Using this vector type, for the first time expression rates were obtained that were identical to the parental hybridoma. The use of the gpt selection marker seems to be crucial for efficient expression, and may overcome a recently claimed drawback of vector integration. A chimeric antibody produced by gene targeting was characterized in vitro and in vivo.     

Evaluation of postsurgical crestal bone levels adjacent to non‐submerged dental implants

In most of the studies on long-term radiographic evaluations of crestal bone levels adjacent to dental implants, no baseline radiographs taken immediately post-surgically had been obtained.The aim of this study was to test the reproducibility of a simple radiographic method for linear measurements of changes in bone levels and to evaluate changes in crestal bone levels adjacent co non-submerged ITI® implants 1 year following the surgical procedure. From 128 patients enrolled in a clinical and radiographic longitudinal study 40 patients also had radiographs taken immediately postsurgically. They were, however, not obtained as “identical” images. The radiographs were mounted onto slides and projected on a screen. Mesially and distally from 57 implants triplicate linear measurements of the distance implant shoulder to bone crest were taken, using known dimensions of the implants as internal reference distances. The median difference of 213 (out of 228 possible) duplicate measurements was 0.00 mm (ranging from ?1.72 mm to +1.47 mm when comparing the second co the third reading). Some 81% of the double measurements were within ±0.5 mm and the precision was 0.30 mm. In the immediate postoperative radiographs the median mesial bone level was located at 2.07 mm (distally 2.19 mm) from the implant shoulder. A statistically significant amount of bone loss in the first year was observed mesially (median=?0.78 mm) and distally (0.85 mm)(Wilcoxon matched pairs signed rank test ±0.001). No statistically significant influence of the implant location, the implant length, type of the implant (screw; cylinder) was observed (Kruskal-Wallis P>0.05).The age of the patients was not correlated significantly to the amount of bone loss observed. In conclusion, methodological limitations existed when evaluating linear bone changes in non-identical radiographs using reference dimensions of the implants. The amount of postsurgical bone loss estimated in other studies was confirmed when using an immediate postoperative radiograph as a baseline.     

牛胎盘中肝细胞生长因子的纯化

用高速离心、分段盐析、亲和层析、超滤和阴离子交换层析法，从牛胎盘中分离纯化出一种肝细胞生长因子。结果表明，此因子的最终得率为０．００５ｍｇ／ｇ牛胎盘，其分子量约为９９０００ｕ，它能强烈刺激原代培养大鼠肝细胞的ＤＮＡ合成。提示利用自制的亲和层析凝胶，通过此提纯流程可以得到一种肝细胞生长因子。     

Split tolerance in chimeric GVH mice

Abstract The i.v. inoculation of parental spleen cells into unirradiated adult F1 hybrid mice results in a graft-versus-host reaction (GVHR). In the strain combination B10D2±(B10.BRx B10.D2) F1, this reaction is associated with thymic injury and transient but profound cellular immune deficiency. We further analysed the immune status of these mice 60 days after GVHR induction. Phenotypic studies of spleen cells showed that these mice were re-populated with parental lymphocytes resulting in a high degree of chimerism (85%). At this time, the mice looked healthy and recovered a normal cytotoxic T cell response (CTL) against allogeneic cells. GVH chimeric splenocytes were unresponsive against F 1 hybrid cells in mixed lymphocyte culture (MLC), but exhibited anti-F1 CTL reactivity. We also analysed the anti-F 1 reactivity of these mice in vivo. GVH chimeric splenocytes were unable to induce GVHR after injection into a new F1 hybrid and F1 GVH mice specifically rejected F1 bone marrow (BM) cells after lethal irradiation. Grafting a neonatal parental thymus prevented the rejection of F1 BM cells and restored CTL alloreactivity. It is concluded that the chimeric state induced by GVHR is associated with a split tolerance and that a radiosensitive thymic-dependent mechanism is involved in maintaining self-tolerance in these mice.