Allelic loss of chromosomes 8 and 19 in MENX‐associated rat pheochromocytoma

Pheochromocytomas are neoplasias of neural crest origin that arise from the chromaffin cells of the adrenal medulla. Pheochromocytomas arise with complete penetrance in rats homozygous for a germ‐line frameshift mutation of Cdkn1b, encoding the cell cycle inhibitor p27KIP1 (MENX syndrome). We performed a genome‐wide scan for allelic imbalance comparing 20 rat pheochromocytoma DNAs with normal rat DNA to better understand the pathobiology of the tumors and to correlate the findings with human pheochromocytoma. We identified allelic imbalance (AI) at candidate regions on rat chromosomes 8 and 19. Interestingly, the regions often lost in rat tumors are syntenic to regions involved in human pheochromocytomas. Fluorescence in situ hybridization analysis further validated the AI data. Sdhd and Rassf1a were analyzed in detail as they map to regions of AI on chromosome 8 and their homologues are implicated in human pheochromocytoma: we found no genetic mutations nor decreased expression. We also analyzed additional candidate genes, that is, rat homologues of genes predisposing to human pheochromocytoma and known tumor‐suppressor genes, but we found no AI. In contrast, we observed frequent overexpression of Cdkn2a and Cdkn2c, encoding the cell cycle inhibitors p16INK4a and p18INK4c, respectively. The relative small number of allelic changes we found in rat pheochromocytoma might be related to their nonmalignant status and losses at chromosomes 8 and 19 are events that precede malignancy. Because of the high concordance of affected loci between rat and human tumors, studies of the MENX‐associated pheochromocytomas should facilitate the identification of novel candidate genes implicated in their human counterpart.     

Foxp3+ regulatory T‐cell homeostasis quantitatively differs in murine peripheral lymph nodes and spleen

Regulatory T (Treg) cells are essential for maintaining self‐tolerance and modulating inflammatory immune responses. Treg cells either develop within the thymus or are converted from CD4⁺ naive T (Tnaive) cells in the periphery. The Treg‐cell population size is tightly controlled and Treg‐cell development and homeostasis have been intensively studied; however, quantitative information about mechanisms of peripheral Treg‐cell homeostasis is lacking. Here we developed the first mathematical model of peripheral Treg‐cell homeostasis, incorporating secondary lymphoid organs as separate entities and encompassing factors determining the size of the Treg‐cell population, namely thymic output, homeostatic proliferation, peripheral conversion, transorgan migration, apoptosis, and the Tnaive‐cell population. Quantitative data were collected by monitoring Tnaive‐cell homeostasis and Treg‐cell rebound after selective in vivo depletion of Treg cells. Our model predicted the previously unanticipated possibility that Treg cells regulate migration of Tnaive cells between spleen and peripheral lymph nodes (LNs), whereas migration of Treg cells between these organs can largely be neglected. Furthermore, our simulations suggested that peripheral conversion significantly contributed to the maintenance of the Treg‐cell population, especially in LNs. Hence, we provide the first estimation of the peripheral Treg‐cell conversion rate and propose additional facets of Treg‐cell‐mediated immune regulation that may previously have escaped attention.     

Preexisting antigen‐specific immune responses are modulated by oral KLH feeding in humans

Oral tolerance is the antigen‐specific inhibition of a systemic immune response after oral antigen uptake and well established in animal models. We recently showed that keyhole limpet hemocyanin (KLH) feeding modulates subsequently induced systemic immune responses in humans as well. In the present study, we investigated whether oral KLH can also modulate preexisting antigen‐specific systemic B‐ and T‐cell responses. We induced delayed‐type hypersensitivity (DTH) reactions as well as systemic KLH‐specific B‐ and T‐cell responses by subcutaneous KLH injections. Subsequent oral KLH administration decreased the small proportion of antigen‐specific CD4⁺ T cells positive for the cytokine IL‐17 at the end of the feeding regimen even further. After reimmunization, there was no difference in DTH reactions and the KLH‐specific B‐cell responses, but KLH‐fed volunteers had an increased proportion of antigen‐specific CD4⁺ T cells positive for IL‐10 and a reduced proportion of antigen‐specific CD4⁺ T cells positive for the skin‐homing receptor cutaneous lymphocyte antigen and IL‐2 and IFN‐γ. Taken together, oral KLH can modulate a preexisting systemic KLH‐specific immune response. These results suggest that feeding antigen may offer therapeutic strategies for the suppression of unwanted immune reactions in humans.     

Vacuolating Cytotoxin of Helicobacter pylori Induces Apoptosis in the Human Gastric Epithelial Cell Line AGS

Helicobacter pylori induces cell death by apoptosis. However, the apoptosis-inducing factor is still unknown. The virulence factor vacuolating cytotoxin A (VacA) is a potential candidate, and thus its role in apoptosis induction was investigated in the human gastric epithelial cell line AGS. The supernatant from the vacA wild-type strain P12 was able to induce apoptotic cell death, whereas the supernatant from its isogenic mutant strain P14 could not. That VacA was indeed the apoptosis-inducing factor was demonstrated further by substantial reduction of apoptosis upon treatment of AGS cells with a supernatant specifically depleted of native VacA. Furthermore, a recombinant VacA produced in Escherichia coli was also able to induce apoptosis in AGS cells but failed to induce cellular vacuolation. These findings demonstrate that the vacuolating cytototoxin of H. pylori is a bacterial factor capable of inducing apoptosis in gastric epithelial cells.     

In vivo and in vitro effects of imidacloprid on sheep keds (Melophagus ovinus): a light and electron microscopic study

The effects of imidacloprid (Advantage) on sheep keds (Melophagus ovinus Linné 1758) were studied in vivo and in vitro by means of direct observation (monitored on video tape) and by light and electron microscopy. It was found that: 1. Imidacloprid acted rapidly on all motile stages of the sheep keds. Within 3–4 min after exposure they became immobile and their legs and the abdomen started tetanic trembling movements for 15–30 min, leading to death. 2. The compound is apparently taken up by the body, since it also acted on those sheep keds that had been exclusively exposed to imidacloprid-contaminated filter papers. 3. The compound is available and active for more than 1 month in the wool of sheep; even rainfall does not reduce its efficacy. Body contact between treated mother sheep and their lambs protects them from infestation with these ectoparasites. 4. The compound initiates an ultimately lethal destruction of the ganglia, nerve chords and related muscle fibers, as can be seen in electron micrographs. Received: 7 October 2000 / Accepted: 18 October 2000     

Intra-operative adjustment of standard planes in C-arm CT image data

Purpose

With the help of an intra-operative mobile C-arm CT, medical interventions can be verified and corrected, avoiding the need for a post-operative CT and a second intervention. An exact adjustment of standard plane positions is necessary for the best possible assessment of the anatomical regions of interest but the mobility of the C-arm causes the need for a time-consuming manual adjustment. In this article, we present an automatic plane adjustment at the example of calcaneal fractures.

Methods

We developed two feature detection methods (2D and pseudo-3D) based on SURF key points and also transferred the SURF approach to 3D. Combined with an atlas-based registration, our algorithm adjusts the standard planes of the calcaneal C-arm images automatically. The robustness of the algorithms is evaluated using a clinical data set. Additionally, we tested the algorithm’s performance for two registration approaches, two resolutions of C-arm images and two methods for metal artifact reduction.

Results

For the feature extraction, the novel 3D-SURF approach performs best. As expected, a higher resolution (\(512^3\) voxel) leads also to more robust feature points and is therefore slightly better than the \(256^3\) voxel images (standard setting of device). Our comparison of two different artifact reduction methods and the complete removal of metal in the images shows that our approach is highly robust against artifacts and the number and position of metal implants.

Conclusions

By introducing our fast algorithmic processing pipeline, we developed the first steps for a fully automatic assistance system for the assessment of C-arm CT images.

     

Clinical outcomes of different first- and second-generation drug-eluting stents in routine clinical practice: results from the prospective multicenter German DES.DE registry

Background

Second-generation drug-eluting stents (DES) have provided better results over both bare-metal stents and first-generation DES. However, comparative data of different first- and second-generation DES in a clinical setting of all-comers have not been well studied.

Methods and results

Baseline clinical and angiographic characteristics and in-hospital and follow-up events were recorded for enrolled patients. The composite of death, myocardial infarction, and stroke, defined as major adverse cardiac and cerebrovascular events (MACCE), as well as target vessel revascularization (TVR) was used as the primary end point. Between May 2007 and May 2009, 10,852 patients subjected to drug-eluting stent implantation were enrolled at 74 sites. 3,032 patients (27.9 %) were treated with Taxus?, 4,382 (40.4 %) with Cypher?, 1,012 (9.3 %) with Endeavor?, 1,693 (15.6 %) with Xience V? and 733 (6.8 %) with Promus? during this period. At 1-year follow-up, the comparison between groups revealed no significant differences with respect to overall death, MACCE, definite stent thrombosis, TVR, stroke and major bleeding. After adjustment for risk factors in final regression models, a modestly significant association of DES type to MACCE was observed (p = 0.046); however, this association could not be attributed to one particular DES. An impact of DES type on TVR was not seen after risk adjustment.

Conclusion

Data generated from the prospective German drug-eluting stent (DES.DE) registry confirm that safety and efficacy of different first- and second-generation DES are clinically equivalent in the first year of follow-up, even in a more complex setting.     

Articular surface segmentation using active shape models for intraoperative implant assessment

Purpose

In orthopedic surgeries, it is important to avoid intra-articular implant placements, which increase revision rates and the risk of arthritis. In order to support the intraoperative assessment and correction of surgical implants, we present an automatic detection approach using cone-beam computed tomography (CBCT).

Methods

Multiple active shape models (ASM) with specified articular surface regions are used to isolate the joint spaces. Fast and easy-to-implement methods are integrated in the ASM segmentation to optimize the robustness and accuracy for intraoperative application. A cylinder detection method is applied to determine metal implants. Intersections between articular surfaces and cylinders are detected and used to find intra-articular collisions.

Results

Segmentations of two calcaneal articular surfaces were evaluated on 50 patient images and have shown average surface distance errors of 0.59 and 0.46 mm, respectively. The proposed model-independent segmentation at the specified articular surface regions allowed to significantly decrease the error by 22 and 25 % on average. The method was able to compensate suboptimal initializations for translations of up to 16 mm and rotations of up to 21\(^{\circ }\). In a human cadaver test, articular perforations could be localized with an accuracy of 0.80 mm on average.

Conclusions

A concept for automatic intraoperative detection of intra-articular implants in CBCT images was presented. The results show a reliable segmentation of articular surfaces in retrospective patient data and an accurate localization of misplaced implants in artificially created human cadaver test cases.