The Lectin LecB Induces Patches with Basolateral Characteristics at the Apical Membrane to Promote Pseudomonas aeruginosa Host Cell Invasion.

The opportunistic bacterium Pseudomonas aeruginosa can infect mucosal tissues of the human body. To persist at the mucosal barrier, this highly adaptable pathogen has evolved many strategies, including invasion of host cells. Here, we show that the P. aeruginosa lectin LecB binds and cross-links fucosylated receptors at the apical plasma membrane of epithelial cells. This triggers a signaling cascade via Src kinases and phosphoinositide 3-kinase (PI3K), leading to the formation of patches enriched with the basolateral marker phosphatidylinositol (3,4,5)-trisphosphate (PIP3) at the apical plasma membrane. This identifies LecB as a causative bacterial factor for activating this well-known host cell response that is elicited upon apical binding of P. aeruginosa. Downstream from PI3K, Rac1 is activated to cause actin rearrangement and the outgrowth of protrusions at the apical plasma membrane. LecB-triggered PI3K activation also results in aberrant recruitment of caveolin-1 to the apical domain. In addition, we reveal a positive feedback loop between PI3K activation and apical caveolin-1 recruitment, which provides a mechanistic explanation for the previously observed implication of caveolin-1 in P. aeruginosa host cell invasion. Interestingly, LecB treatment also reversibly removes primary cilia. To directly prove the role of LecB for bacterial uptake, we coated bacterium-sized beads with LecB, which drastically enhanced their endocytosis. Furthermore, LecB deletion and LecB inhibition with l-fucose diminished the invasion efficiency of P. aeruginosa bacteria. Taken together, the results of our study identify LecB as a missing link that can explain how PI3K signaling and caveolin-1 recruitment are triggered to facilitate invasion of epithelial cells from the apical side by P. aeruginosa. IMPORTANCE An intriguing feature of the bacterium P. aeruginosa is its ability to colonize highly diverse niches. P. aeruginosa can, besides forming biofilms, also enter and proliferate within epithelial host cells. Moreover, research during recent years has shown that P. aeruginosa possesses many different mechanisms to invade host cells. In this study, we identify LecB as a novel invasion factor. In particular, we show that LecB activates PI3K signaling, which is connected via a positive feedback loop to apical caveolin-1 recruitment and leads to actin rearrangement at the apical plasma membrane. This provides a unifying explanation for the previously reported implication of PI3K and caveolin-1 in host cell invasion by P. aeruginosa. In addition, our study adds a further function to the remarkable repertoire of the lectin LecB, which is all brought about by the capability of LecB to recognize fucosylated glycans on many different niche-specific host cell receptors.

[Magdeburg Medical School - Logbook for Surgical Training of Final Year Medical Students - an Interdisciplinary, Medical School-Specific Concept Based on the Guidelines Issued by the Medical School Association ("Medizinischer Fakultätentag") in 2012]. / Magdeburger PJ-Logbuch der chirurgischen Fächer ­ interdisziplinäre, einrichtungsspezifische Umsetzung der Vorgabe des Medizinischen Fakultätentages (MFT) von 2012.

BACKGROUND: The final year is the last part of the study of human medicine and can be regarded as an essential period, during which medical knowledge should be consequently converted into medical expertise. Since the amendment of the medical license policy ("Ärztliche Approbationsordnung" [ÄApprO]) from July 17, 2012, in particular, since April 01, 2013, German universities have been obliged to provide a training schedule such as a "logbook" for this final year, specifically for the mandatory time periods within surgery and internal medicine. In preparation for this innovation, the German Medical School Association ("Medizinischer Fakultätentag") presented basic logbooks as consensus documents in June 2012. The portfolio for each surgery discipline and the Magdeburg Medical School, had been developed on the basis of individual initiatives and used for years, and was revised, specified and further developed into a "logbook of the medical study's final year" - specific for daily practice and the Magdeburg Medical School, and to the guidelines of the Medical School Association ("Medizinischer Fakultätentag"). The aim of the present commentary is i) to present the Magdeburg Medical School logbook and its clinical planning for cases, diagnoses and (surgical) interventions, as a summary of institutional experience and ii) to describe the mandatory surgical part of the "Magdeburg's final year of the study of human medicine". METHOD: Narrative short overview including individual teaching experiences and topic-related references from "PubMed" using terms for literature search such as "surgical logbook", "practical year" and "medical teaching". The background and aims of the document's modifications are explained for each surgical discipline. RESULTS: The "Logbook" is subdivided into 6 chapters: introduction, basics, statement of requirement, selected surgical diseases and interventions as well as information on final year-associated events and courses and instructions for creating the obligatory case report. CONCLUSION: The presented "Magdeburg Medical School Final Year Logbook of the Surgical Disciplines" has been created according to the requirements of the German Medical School Association ("Medizinischer Fakultätentag") and has been simultaneously adapted to the conditions and established medical teaching at the presenting Medical School. In particular, the medical students are given a document related to daily clinical practice, which allows them, within an overall teaching concept, to acquire indispensable expertise.

The Pseudomonas aeruginosa Lectin LecB Causes Integrin Internalization and Inhibits Epithelial Wound Healing.

The opportunistic bacterium Pseudomonas aeruginosa produces the fucose-specific lectin LecB, which has been identified as a virulence factor. LecB has a tetrameric structure with four opposing binding sites and has been shown to act as a cross-linker. Here, we demonstrate that LecB strongly binds to the glycosylated moieties of ß1-integrins on the basolateral plasma membrane of epithelial cells and causes rapid integrin endocytosis. Whereas internalized integrins were degraded via a lysosomal pathway, washout of LecB restored integrin cell surface localization, thus indicating a specific and direct action of LecB on integrins to bring about their endocytosis. Interestingly, LecB was able to trigger uptake of active and inactive ß1-integrins and also of complete α3ß1-integrin-laminin complexes. We provide a mechanistic explanation for this unique endocytic process by showing that LecB has the additional ability to recognize fucose-bearing glycosphingolipids and causes the formation of membrane invaginations on giant unilamellar vesicles. In cells, LecB recruited integrins to these invaginations by cross-linking integrins and glycosphingolipids. In epithelial wound healing assays, LecB specifically cleared integrins from the surface of cells located at the wound edge and blocked cell migration and wound healing in a dose-dependent manner. Moreover, the wild-type P. aeruginosa strain PAO1 was able to loosen cell-substrate adhesion in order to crawl underneath exposed cells, whereas knockout of LecB significantly reduced crawling events. Based on these results, we suggest that LecB has a role in disseminating bacteria along the cell-basement membrane interface.IMPORTANCEPseudomonas aeruginosa is a ubiquitous environmental bacterium that is one of the leading causes of nosocomial infections. P. aeruginosa is able to switch between planktonic, intracellular, and biofilm-based lifestyles, which allows it to evade the immune system as well as antibiotic treatment. Hence, alternatives to antibiotic treatment are urgently required to combat P. aeruginosa infections. Lectins, like the fucose-specific LecB, are promising targets, because removal of LecB resulted in decreased virulence in mouse models. Currently, several research groups are developing LecB inhibitors. However, the role of LecB in host-pathogen interactions is not well understood. The significance of our research is in identifying cellular mechanisms of how LecB facilitates P. aeruginosa infection. We introduce LecB as a new member of the list of bacterial molecules that bind integrins and show that P. aeruginosa can move forward underneath attached epithelial cells by loosening cell-basement membrane attachment in a LecB-dependent manner.

Aggressive digital papillary adenocarcinoma - a rare malignant tumor of the sweat glands: two case reports and a review of the literature.

Aggressive digital papillary adenocarcinomas are rare malignant tumors often located on the digits of the hand. Due to lack of pain, slow growth, and an inconspicuous appearance, diagnosis is often missed or delayed. We report two cases and review the present literature to give recommendations for diagnosis and treatment.

Genital Reconstruction After Weight Loss in Adipose Male Patients: A Case report.

OBJECTIVE: We introduce our surgical technique in two male genital reconstruction cases out of 15 post-bariatric patients. METHODS: At our Department for Plastic Surgery at the University Hospital Magdeburg, 15 patients, 6 male and 9 female, underwent a surgical abdominoplasty after weight loss in 2009. RESULTS: The average weight of the 15 patients was preoperatively 197.2 kg and the average hospital stay was of 14 days. In 2 cases, a second procedure for male genital reconstruction was necessary. After primary dietary measures and weight loss, we performed genital reconstruction in a second step with a sleeve-, Z-, VY-plasty and a "bilobed flap" to restore function and appearance of the male genitalia. In these patients, the average weight was 207.5 kg and hospital stay lasted 32 days. CONCLUSION: The increase of patients with obesity-related genital deformities will be expected in the future. Therefore, more controlled long-term studies should be published to develop guidelines for genital reconstruction techniques in plastic surgery.

Operative decisions for endoscopic treatment of cubital tunnel syndrome.

The authors review the relevant anatomy and provide technical tips for endoscopic decompression of the cubital tunnel. Cubital tunnel syndrome is the second most common nerve compression syndrome in the upper extremity. Until recently, surgeons focused on open decompression combined with submuscular or subcutaneous transposition of the nerve. Decompression was usually limited to the region of the medial epicondyle, and related morbidity was relatively high. Endoscopic decompression is a promising technique because the dissection range can be extended and the scar length can be reduced. The authors review the relevant anatomy for the endoscopic approach and give some recommendations concerning the details of the surgical technique.

Custom-made wrist prosthesis in a patient with giant cell tumor of the distal radius.

INTRODUCTION: Treatment for giant cell tumors of the distal radius is challenging when motion is to be preserved. As standard wrist prostheses typically do not achieve favorable results, we treated a 36-year-old man with giant cell tumor of the distal radius with a new, custom-made implant. METHODS: A custom-made wrist prosthesis with a long shaft was designed according to the patient's X-ray findings. After complete tumor resection, the prosthesis was subsequently implanted into the distal radius without complications. RESULTS: Two months after surgery, range of motion was 30°-0-25° for extension/flexion, 10°-0-5° for ulnar/radial abduction, 80°-0-0 for pronation/supination, complete range of motion for the fingers, and a grip strength of 6 kg. Two years after surgery, implant position was still correct and range of motion was 45°-0-10° for extension/flexion, 10°-0-20° for ulnar/radial abduction, and 80°-0-10° for pronation/supination. Grip strength was 16 kg, and DASH score was 25 compared to 39 before surgery. The patient returned to work as a craftsman. CONCLUSION: Custom-made wrist prostheses could become a practical option in patients with large defects of the distal radius who desire to preserve wrist motion.

Syndromes with focal overgrowth in infancy: diagnostic approach and surgical treatment.

Syndromes with focal overgrowth are sporadic diseases and comprise Proteus syndrome and congenital lipomatous overgrowth, vascular malformations, and epidermal naevi (CLOVE) syndrome, and isolated hemihyperplasia. We describe 3 children classified according to standard criteria with dysregulated growth of various tissues that was excised, together with excess toes, and tumours. Correct classification facilitates diagnosis and operations. Interdisciplinary treatment and follow-up are recommended to prevent disfiguration.

Stimulation of Schwann cell proliferation and axonal regeneration by FK 506.

PURPOSE: Nerve allografts are highly antigenic and, thus, require the continuous use of immunosuppressive drugs. FK 506 was found to pre-vent rejection successfully. However, clinically neurotoxic complications have been noted in the central and peripheral nervous system although an increased rate of axonal regeneration has also been shown after nerve crush experiments. To investigate whether a possible regeneration pro-moting potency of FK 506 is determined via an influence on Schwann cells, Schwann cells were cultured from the sciatic nerve of the rat. METHODS: The effect of 100 micro M FK 506 administered daily on these cultures was assessed microscopically over a period of seven days and compared to an untreated control group of cultures. Additionally, the changes in intracellular calcium were recorded using a laser scanning microscope. In vivo regeneration of autologous rat sciatic nerve grafts was assessed clinically, histologically and morphometrically after two and six weeks. The animals received a daily administration of 0.6 mg FK 506/kg body weight, the control received saline. RESULTS: In vitro FK 506 increased the Schwann cell number in culture significantly compared to non treated cultures, while the fibrocyte population was decreased. FK 506 caused a transient increase of intracellular calcium levels in cultured cells. In vivo, a significantly higher axon count was observed in the FK 506 treated grafts after two weeks regeneration compared with controls. Good regeneration was noted in all grafts after six weeks regeneration. CONCLUSIONS: The increased axon counts and decreased myelin debris in the FK 506 grafts after two weeks indicate an accelerated Wallerian degeneration and increased axon sprouting into the graft initially. The inhibition of calcineurin activity is not the mediator of the neurotrophic effect. FK 506 promotes axonal regeneration through binding to FKBP-12. The increase of intracellular calcium may induce Schwann cell pro-liferation via calmodulin. The therapeutic relevance for autologous nerve grafting, however, has to be defined in further studies.