Forest and woodland replacement patterns following drought-related mortality.

Forest vulnerability to drought is expected to increase under anthropogenic climate change, and drought-induced mortality and community dynamics following drought have major ecological and societal impacts. Here, we show that tree mortality concomitant with drought has led to short-term (mean 5 y, range 1 to 23 y after mortality) vegetation-type conversion in multiple biomes across the world (131 sites). Self-replacement of the dominant tree species was only prevalent in 21% of the examined cases and forests and woodlands shifted to nonwoody vegetation in 10% of them. The ultimate temporal persistence of such changes remains unknown but, given the key role of biological legacies in long-term ecological succession, this emerging picture of postdrought ecological trajectories highlights the potential for major ecosystem reorganization in the coming decades. Community changes were less pronounced under wetter postmortality conditions. Replacement was also influenced by management intensity, and postdrought shrub dominance was higher when pathogens acted as codrivers of tree mortality. Early change in community composition indicates that forests dominated by mesic species generally shifted toward more xeric communities, with replacing tree and shrub species exhibiting drier bioclimatic optima and distribution ranges. However, shifts toward more mesic communities also occurred and multiple pathways of forest replacement were observed for some species. Drought characteristics, species-specific environmental preferences, plant traits, and ecosystem legacies govern postdrought species turnover and subsequent ecological trajectories, with potential far-reaching implications for forest biodiversity and ecosystem services.

Utility of component analyses in subjects undergoing sublingual immunotherapy for peanut allergy.

BACKGROUND: Sublingual immunotherapy (SLIT) with peanut changes clinical and immune responses in most peanut-allergic individuals, but the response is highly variable. OBJECTIVE: We sought to examine the component-specific effects of peanut SLIT and determine whether peanut component testing could predict the outcome of a double-blind, placebo-controlled food challenge (DBPCFC) after 12 months of peanut SLIT. METHODS: We included 33 subjects who underwent peanut SLIT with a DBPCFC of 2500 mg of peanut protein performed after 12 months of therapy. Plasma samples from baseline and after 12 months of peanut SLIT were assayed using ImmunoCAP for IgE and IgG4 against whole peanut, Ara h 1, Ara h 2, Ara h 3, Ara h 8, and Ara h 9. RESULTS: Following 12 months of SLIT, 10 subjects (30%) passed the DBPCFC without symptoms and were considered desensitized. Subjects that failed the DBPCFC tolerated a median of 460 mg peanut protein (range: 10-1710 mg). The desensitized group had significantly lower baseline levels of IgE against peanut (median 40.8 vs. 231 kUA /L, P = 0.0082), Ara h 2 (median 17 vs. 113 kUA /L, P = 0.0082), and Ara h 3 (median 0.3 vs. 8.5 kUA /L, P = 0.0396). ROC curves indicated that baseline IgE against peanut and Ara h 2 were equally effective at discriminating between the two groups (AUC = 0.7957, P = 0.007752 for both). CONCLUSION AND CLINICAL RELEVANCE: In this cohort of subjects undergoing SLIT for peanut allergy, lower baseline levels of IgE against Ara h 2, Ara h 3, and peanut were associated with successful desensitization.

High rate of galactose-alpha-1,3-galactose sensitization in both eosinophilic esophagitis and patients undergoing upper endoscopy.

Eosinophilic esophagitis (EoE) is an antigen/allergy-mediated chronic inflammatory condition. The rapid rise in the number of cases of EoE suggests an as-yet undiscovered environmental trigger. This study tested the hypothesis that immunoglobulin E (IgE) to galactose-alpha-1,3-galactose (alpha-gal), a newly recognized sensitization induced by a tick bite that causes mammalian meat allergy, is a risk factor for EoE. We conducted a case-control study using prospectively collected and stored samples in the University of North Carolina EoE Patient Registry and Biobank. Serum from 50 subjects with a new diagnosis of EoE and 50 non-EoE subjects (either with gastroesophageal reflux disease or dysphagia from non-EoE etiologies) was tested for alpha-gal-specific IgE using an ImmunoCAP-based method. Specific IgE > 0.35 kUA /L was considered a positive result. Subjects with EoE were a mean of 35 years old, 68% were male, and 94% were white. Non-EoE controls were a mean of 42 years, 50% were male, and 78% were white. A total of 22 (22%) subjects overall had alpha-gal-specific IgE > 0.35 kUA /L. Of the EoE cases, 12 (24%) were positive, and of the non-EoE controls, 10 (20%) were positive (p=0.63). Neither the proportion sensitized nor the absolute values differed between EoE and non-EoE subjects. We found a similar but high rate of alpha-gal sensitization in patients with EoE as found in non-EoE controls who were undergoing endoscopy. While our data do not support alpha-gal sensitization as a risk factor for EoE, the high rates of sensitization observed in patients undergoing upper endoscopy for symptoms of esophageal dysfunction is a new finding.

[Gastric and duodenal perforations: what is the role of laparoscopic surgery?]. / Magen- und Duodenalperforation: Welchen Stellenwert hat die laparoskopische Chirurgie?

INTRODUCTION: The gastric and duodenal perforations are a life-threatening complication of peptic ulcer disease with the indication for immediate surgical intervention. To which extent laparoscopy is a suitable method in an acute situation was examined in the present investigation. MATERIALS AND METHODS: The data of all patients within a period of 15 years (01/1996-12/2010) who were operated laparoscopically because of a perforated gastric or duodenal ulcer, were collected prospectively in terms of age, gender, localisation of perforation, diagnostics, symptoms, surgical procedures, intraoperative and postoperative complications and postoperative course, and were analysed retrospectively. RESULTS: During the observation period 45 patients were operated laparoscopically due to gastric or duodenal perforation. The median age at operation was 58 (18-91) years. An NSAID medication was present in 11 (24.4 %) patients. The perforation was juxtapyloric in 12 (26.7 %) patients, postpyloric in 10 (22.2 %) patients, one (2.2 %) patient in each small and greater curvature, in 18 (40.0 %) at the front and in three (6.7 %) patients on the rear wall. In two cases, previous surgical treatment in the upper abdomen was performed. After primary diagnostic laparoscopy, an indication for conversion was seen in 20 (44.4 %) patients. During laparoscopically completed operations simple suturing was done in 18/25 (72.0 %) patients and excision and suturing was performed in 7/25 (37.8 %) patients. After conversion simple suturing was observed in 7/20 (35.0 %) patients, whereas in 10/20 (50.0 %) patients excision and suturing was performed. 3/20 (15.0 %) patients underwent a resective operation. The median operative time was 105 (40-306) minutes and mean hospitalisation 11 (4-66) days. The ICU stay was in median 2 (0-37) days. Major complications were seen in 11 (24.4 %) patients, namely re-laparotomy (n = 7; 15.6 %) and haemorrhage (n = 4; 8.9 %). Minor complications were observed in 8 (17.8 %) of cases. The mortality rate was 11.1 % (n = 5). CONCLUSION: The laparoscopic treatment of gastric and duodenal perforations is a minimally invasive therapeutic option for the definitive treatment of this life-threatening disease. The indication for a laparoscopic approach has to be considered individually and depends to a decisive extent on the experience of the laparoscopic surgeon.

[Diagnostics and therapy for neuroendocrine neoplasia of an unknown primary - a plea for open exploration]. / Diagnostik und Therapie bei neuroendokrinen Neoplasien mit unklarem Primarius - ein Plädoyer für die offene Exploration.

BACKGROUND: Neuroendocrine neoplasia (NEN) are a rare and heterogenous tumour entity. The subgroup with unknown primary tumour (N-CUP) seems to have a worse prognosis as resection of the primary is necessary for cure. The diagnostics and therapeutic algorithms for N-CUP in a German single centre are presented. PATIENTS/METHODS: Analysis of the surgical databank showed 35 cases of N-CUP in 261 cases with NEN from gastroenteropancreatic and lung origin over 2 decades (03/1990-03/2011). Three groups were built: K1 - primary detection after operative exploration (n = 10), K2 - unknown primary after operative exploration (n = 10) and K3 - no operative exploration for various reasons (n = 13). RESULTS: Initially 13.4 % (35/261) of patients presented as N-CUP, after intensified diagnostics 12.7 % (33/261) and after operative exploration 8.8 % (23/261) remained with unknown primary tumour. The sex ratio was 1 : 1, the median age is significantly higher in N-CUP [63.8 years (y) vs. 55.9 y, p = 0.004), the 5-year-survival is lower (58 vs. 72 %, n. s.). compared to NEN with known primary. Operative exploration was performed in 60.6 % (20/33), 30 % (6/20) of them were found to have inoperable situations, in 20 % (4/20) single site metastases were removed completely and in 50 % (10/20) a primary tumour was detected (8 × midgut, 2 × pancreas) intraoperatively. In these cases 70 % (7/10) got complete tumour resection (R0) and in 30 % (3/10) primary tumour resection with debulking of liver metastasis was done. In K3 (39.4 %, 13/33) most patients [69.2 % (9/13)] were treated with chemotherapy. The median age in K1 was significantly lower than in K3 (54.9 y vs. 68.3 y, p = 0.028), male dominance was seen in K3 (3,3 : 1, n. s.). The average Ki-67 index was 4.3, 23.8 and 53 % in K1, K2 and K3 (p < 0.0001 for K1 and K3 and p = 0.035 for K2 and K3), respectively. The death rate was 20, 30 and 76.9 % in K1, K2 and K3, respectively. CONCLUSION: Primary tumours of the midgut and pancreas are often found in the subset of well differentiated neuroendocrine CUP syndrome after open surgical exploration. A high rate of complete tumour resection and cure can be achieved in these cases. After common diagnostic tools (CT, MRI and somatostatin receptor scintigraphy), immunhistochemistry can give important hints (CDX-2 for midgut, TTF-1 for lung and thyroid) for a primary lesion. Also in single site metastasis without primary tumour detection a good clinical outcome is seen after complete resection.

[Neuroendocrine tumours of the GI tract--data from the German NET Registry]. / Neuroendokrine Tumoren des Verdauungstrakts - Daten des deutschen NET-Registers.

BACKGROUND: Neuroendocrine tumours (NET) are rare and heterogeneous neoplasia. To obtain valid data on epidemiology, diagnostics, therapy, prognosis and risk factors is the aim of the German NET registry. PATIENTS AND METHODS: Data from 2009 histologically proven NET were collected from 35 NET centres between 1999 and 2010. Data collection has been performed prospectively since 2004. Results: Median follow-up was 34.5 months and median age at diagnosis 56.4 years. Primary tumour localisations were pancreas (34.2%), midgut (5.8%), stomach (6.5%), bowel (6.9%), duodenum (4.8%) and neuroendocrine CUP (12.6%). Synchronous metastases were seen in 46% and second malignancies in 12%. From 860 patients, 402 (46.7%) had functional tumours with the following hormone excess syndromes: carcinoid syndrome (19.1%; n = 164), persistent hyperinsulinaemic hypoglycaemia (17.7%; n = 152), Zollinger- Ellison syndrome (7.1%; n = 61), glucagonoma (0.7%; n = 15), Verner-Morrison syndrome (0.4%; n = 8) and somatostatinoma syndrome(0.1%; n = 2). Surgical therapy was performed in 78%, therapy with somatostatin receptor analogues(SSA) in 28%, peptide radioreceptor therapy (PRRT) in 19%, chemotherapy in 18% and interferon therapy in 6.5%. Only surgery was done in 47%, whereas 53% received a second therapy. General mortality rate during follow-up was 14.9%. The tumour-specific survival rates for 2, 5 and 10 years were 94, 85 and 70%. The 5-year survival is dependent on the surgical or non-surgical therapy (82 versus 61%, p < 0.001) and also on the primary tumour site (90/30% for midgut, 85/65% for pancreas, p < 0.001). Grading (G1, G2, G3) based on proliferation index Ki-67 recommended by the ENETS guidelines and WHO classification is highly correlated to the 5-year survival rate (88, 82, 33%, p < 0.001). CONCLUSION: The German NET registry provides valid multicentric data on NET in Germany. Surgical therapy is the most frequent and important therapy with good clinical outcome. In non-resectable, metastatic tumours, systemic therapies are common. Continuation and evaluation of the new WHO and TNM classifications for NET and their therapies will be a future focus of the registry.

High-precision nanoscale temperature sensing using single defects in diamond.

Measuring local temperature with a spatial resolution on the order of a few nanometers has a wide range of applications in the semiconductor industry and in material and life sciences. For example, probing temperature on the nanoscale with high precision can potentially be used to detect small, local temperature changes like those caused by chemical reactions or biochemical processes. However, precise nanoscale temperature measurements have not been realized so far owing to the lack of adequate probes. Here we experimentally demonstrate a novel nanoscale temperature sensing technique based on optically detected electron spin resonance in single atomic defects in diamonds. These diamond sensor sizes range from a micrometer down to a few tens of nanometers. We achieve a temperature noise floor of 5 mK/Hz(1/2) for single defects in bulk sensors. Using doped nanodiamonds as sensors the temperature noise floor is 130 mK/Hz(1/2) and accuracies down to 1 mK for nanocrystal sizes and therefore length scales of a few tens of nanometers. This combination of precision and position resolution, combined with the outstanding sensor photostability, should allow the measurement of the heat produced by chemical interactions involving a few or single molecules even in heterogeneous environments like cells.

Obstructive defecation syndrome: 19 years of experience with laparoscopic resection rectopexy.

BACKGROUND: In obstructive defecation syndrome (ODS) combinations of morphologic alterations of the pelvic floor and the colorectum are nearly always evident. Laparoscopic resection rectopexy (LRR) aims at restoring physiological function. We present the results of 19 years of experience with this procedure in patients with ODS. METHODS: Between 1993 and 2012, 264 patients underwent LRR for ODS at our department. Perioperative and follow-up data were analyzed. RESULTS: The female/male ratio was 25.4:1, mean age was 61.3 years (±14.3 years), and mean body mass index (BMI) was 25.2 kg/m(2) (±4.2 kg/m(2)). The pathological conditions most frequently found in combination were a sigmoidocele plus a rectocele (n = 79) and a sigmoidocele plus a rectal prolapse or intussusception (n = 69). The conversion rate was 2.3 % (n = 6). The mortality rate was 0.75 % (n = 2), the rate of complications requiring surgical re-intervention was 4.3 % (n = 11), and the rate of minor complications was 19.8 % (n = 51). Follow-up data were available for 161 patients with a mean follow-up of 58.2 months (±47.1 months). Long-term results showed that 79.5 % of patients (n = 128) reported at least an improvement of symptoms. In cases of a sigmoidocele (n = 63 available for follow-up) or a rectal prolapse II°/III° (n = 72 available for follow-up), the improvement rates were 79.4 % (n = 50) and 81.9 % (n = 59), respectively. CONCLUSIONS: LRR is a safe and effective procedure. Our perioperative results and long-term functional outcome strengthen the evidence regarding benefits of LRR in patients with an outlet obstruction. However, careful patient selection is essential.

[Laparoscopic resection rectopexy as treatment for obstructive defecation syndrome]. / Die laparoskopische Resektionsrektopexie zur Therapie des obstruktiven Defäkationssyndroms.

Anorectal outlet obstruction constitutes one form of chronic constipation. Combinations of morphological alterations of the pelvis, the pelvic floor and the colorectum are nearly always evident. The goal of the diagnostic work-up is to identify those patients who will profit from a surgical intervention. Resection rectopexy aims at restoring the physiological anatomy thereby ameliorating the functional interaction of structures effected with the laparoscopic approach entailing all advantages of minimally invasive surgery. Besides a detailed description of the surgical technique used and an algorithm for indications to operate we present our results after 19 years of experience. Throughout this period, 264 laparoscopic resection rectopexies for outlet obstruction were performed. With a mean follow-up of 58.2 months the rate of improvement of obstructive symptoms was 79.5 % (n = 128 of 161 available for follow-up). Present studies suggest that (laparoscopic) resection rectopexy entails better results in comparison to non-resecting procedures and procedures with the implantation of allogenic material. Certainly, in order to achieve these results a correct patient selection and an expertise in laparoscopic surgery are essential. Both the perioperative and the functional results of our own collective fortify the advantages of laparoscopic resection rectopexy in patients with an outlet obstruction.

The role of organ preservation in the surgical therapy of traumatic spleen injury.

BACKGROUND: New findings on immunological und haematological functions of the spleen, the postoperative risks following splenectomy, as well as improved surgical techniques resulted in an increased interest in organ preservative surgery after traumatic spleen injury in recent years. MATERIAL AND METHODS: The data of all patients who underwent surgery for traumatic spleen injuries between 1995-2009 were recorded prospectively and analysed concerning type of operation, intra-and postoperative complications and the postoperative course. RESULTS: A total of 214 patients with splenic trauma underwent surgery. The spleen could be preserved in 80 patients (37.4%, group 1), using thermocoagulation, suture, glue sealant, splenorhaphy and partial spleen resection or combined techniques. 4 of those patients (5%) required a revision operation, in which two spleens could be salvaged by application of glue sealant. Eight of the patients of group 1 could be treated laparoscopically (10%). CONCLUSION: Under consideration of the surgical segment anatomy of the spleen and the surgical techniques presented, organ preservation is possible with high success rates, even in patients with severe splenic damage. In stable patients with minor splenic injury, laparoscopic or conservative treatment can be considered. Splenectomy should be reserved for patients with complete shattering of the spleen or instable patients.

[Current state of laparoscopic hepatic surgery: results of a survey of DGAV-members]. / Stand der laparoskopischen Leberchirurgie: Ergebnisse einer Umfrage der DGAV-Mitglieder.

BACKGROUND: To date laparoscopic hepatic surgery is only common in a few centres for a specific selected patient group. The intention of this survey was to estimate the current state of affairs for laparoscopic hepatic surgery in Germany at 2008. MATERIALS AND METHODS: A questionnaire was prepared and sent out by e-mail in May 2009 to the members of the DGAV (German Society of General and Visceral Surgery). The feedback was evaluated anonymously. RESULTS: A total of 181 answers were received by 31st July 2009 (return rate of 15.9%). The return rate of basic and standard care hospitals was 9.2%, specialized hospitals 23.6%, hospitals with maximum care 50% and university hospitals had a return rate of 71.9%. The question whether laparoscopic hepatic surgery had been performed in 2008 was answered with YES by 125 (69.1%) and NO by 54 (29.8%) members. The number of laparoscopic hepatic surgery interventions (laparoscopic ultrasound, laparoscopic radiofrequency ablation and resection) in 2008 was given as more than 50 by 4 (2.2%) hospitals, between 20 and 50 by 11 (6.1%) hospitals, between 10 and 20 by 23 (12.7%) hospitals, between 5 and 10 by 45 (24.9%) hospitals and between 0 and 5 by 54 (29.8%) hospitals. In 2008 the frequency of laparoscopic ultrasound during intraoperative staging to confirm the diagnosis ranged from 2 to 250, whereby 96.4% of the hospitals had less than 50 and only 2 hospitals (2.7%) had 211 and 250 examinations, respectively. 50 hospitals carried out laparoscopic radiofrequency ablation (RFA). 69 (38.1%) of the interviewed hospitals reported hepatic laparoscopic resections (n=551). CONCLUSION: Laparoscopic liver surgery has been done in Germany in patients with benign or malignant liver lesions. Pure laparoscopy is the most common access. Atypical resections are the primarily indication followed by left lateral resections. All further types of resection have been done in a very small number. Laparoscopic liver surgery has been performed in all types of hospitals.

New insights into the epidemiology and etiology of Fournier's gangrene: a review of 33 patients.

BACKGROUND: Fournier's gangrene is a necrotizing fasciitis involving the perineal and genital regions. Even today, this often polymicrobial infection still carries a high mortality rate and continues to be a major challenge to the medical community. The purpose of this study was to report our experience with this condition and to compare it with those reported in published studies. We also introduce our approach to treatment. METHODS: We analyzed data from 33 patients with Fournier's gangrene who were managed in our hospital from 1996 to 2007, focusing on patient gender, age, etiology, predisposing conditions, comorbidities, bacteriology, sepsis, blood results, mortality, and spread of gangrene. RESULTS: 18 (54.5%) of the 33 patients had been referred to our department by smaller district hospitals. The patient cohort consisted of 23 men and ten women with a median age of 59 years (range 40-79 years). The median time between the onset of symptoms and progression to gangrene was 6 days (range 2-28 days). An underlying cause was identified in 27 patients (81.8%). The commonest etiological events were perianal and perirectal abscesses (n = 13; 39.4%). Predisposing factors included diabetes mellitus in 12 cases (36.4%), chronic alcoholism in ten cases (30.3%), immunosuppression in six cases (18.2%), and prolonged immobilization in five cases (15.2%). 17 patients (51.5%) had a body mass index (BMI) of 25 or higher, and 13 patients (39.4%) had a BMI of 30 or higher. Positive cultures were obtained in 30 cases (90.9%). In 26 cases (78.8%), multiple microorganisms were recovered, including nine cases (27.3%) with both aerobes and anaerobes. Sepsis was present in 26 patients (78.8%). The mortality rate was 18.2%. CONCLUSION: Fournier's gangrene remains a major challenge with a high mortality. Our results suggest that women are more commonly affected than has generally been assumed. Contrary to published reports, we found that anorectal sources appear to account for more cases of Fournier's gangrene than urological sources.

Prototype of an online navigation system for laparoscopic radiofrequency ablation.

BACKGROUND/AIMS: Laparoscopic Radiofrequency-ablation is a safe and effective method for tumor destruction in patients with unresectable liver tumors. However, accurate probe placement using laparoscopic ultrasound guidance is required to achieve complete tumor ablation. After development and evaluation of laparoscopic navigation tools for radiofrequency ablation, we are now presenting a prototype of a navigation- and documentation-system for laparoscopic RFA. METHODOLOGY: An image-guided surgery system for laparoscopic liver treatments (LapAssistent) based on a 3D-navigation scene was developed. A laparoscopic ultrasound probe and a RFA needle could be navigated using an electromagnetic tracking system. The system was studied using a perfused tumour-mimic-model of a porcine liver. RESULTS: The study showed that laparoscopic ultrasound-guided navigation is technically feasible. The system enables the surgeon to intraoperatively update the three-dimensional planning data in case of new findings. The RFA needle could be placed accurately in a targeted tumour with a targeting error ranging from 5 - 7 mm, even out of the ultrasound plane. In case of multiple tumours lying in close spatial relationship, the documentation module helps to keep track of the already ablated tumours and those that still need to be treated. DISCUSSION: Laparoscopic radiofrequency ablation requires advanced laparoscopic ultrasound skills for accurate placement of the RFA probe. The system adds benefit to laparoscopic RFA enabling the surgeon to place the needle accurately inside the targeted tumours using the navigation scene. The possibility to update the three-dimensional model with new intraoperative findings enables the surgeon to adapt to a new intraoperative situation.

Prototype of an intraoperative navigation and documentation system for laparoscopic radiofrequency ablation: first experiences.

AIMS: Laparoscopic radiofrequency ablation (RFA) is an accepted approach to treat unresectable liver tumours, distinguishing itself from other techniques by combining minimal invasiveness and the advantages of a surgical approach. The major task of laparoscopic RFA is the accurate needle placement according to preoperative planning to achieve complete tumour ablation. This study investigates the value of an image-guided surgery system to accomplish this task. METHODS: An image-guided surgery system for laparoscopic liver treatments (LapAssistent) based on a 3D-navigation scene was developed. A laparoscopic ultrasound probe and a RFA needle could be navigated using an electromagnetic tracking system. The system was studied using a perfused tumour-mimic-model of a porcine liver. Navigating the RFA needle, the tumours were ablated. RESULTS: The system enables the surgeon to intraoperatively update the three-dimensional planning data in case of new findings. The RFA needle could be placed accurately in a targeted tumour, even out of the ultrasound plane. In case of multiple tumours lying in close spatial relationship, the documentation module helps to keep track of the already ablated tumours and those that still need to be treated. CONCLUSION: The system adds benefit to laparoscopic RFA enabling the surgeon to place the needle accurately inside the targeted tumours using the navigation scene. A manual alignment of the preoperative data to the physical space produces a feasible result for a restricted region. A precise measurement of the accuracy of this process has to be done. The possibility to update the three-dimensional model with new intraoperative findings enables the surgeon to adapt to a new intraoperative situation. Furthermore the possibility to mark ablated tumours helps to keep track of the operation plan.

Development of a perfused ex vivo tumor-mimic model for the training of laparoscopic radiofrequency ablation.

BACKGROUND: Laparoscopic radiofrequency ablation (RFA) is a safe and effective method for tumor destruction in patients with unresectable liver tumors. However, accurate probe placement using laparoscopic ultrasound guidance is required to achieve complete tumor ablation. This study aimed to develop a perfusable ex vivo tumor-mimic model for laparoscopic radiofrequency ablation training. METHODS: After rinsing the prepared liver vessels with anticoagulants, porcine livers were perfused. Tumor-mimics were created by injecting a mixture consisting of 3% agarose, 3% cellulose, 7% glycerol, and 0.05% methylene blue, creating hyperechoic lesions in ultrasound. Heparinized porcine blood was used as perfusion medium. Continuous perfusion of the porcine liver was provided by connection of a pump system to the portal vein and the vena cava inferior. Laparoscopic RFA techniques were taught using a laparoscopic pelvi-trainer. RESULTS: A total of 30 laparoscopic ablations were performed in four porcine livers. The simulated "tumors" were clearly visible on laparoscopic ultrasound and not felt during placement of the RFA probe. In addition, color duplex ultrasound showed clear signals indicating for a sufficient liver perfusion. CONCLUSION: Laparoscopic RFA requires advanced laparoscopic ultrasound skills for an accurate placement of the RFA probe. The perfused tumor-mimic model presented is a safe, easy, effective, and economic method to improve and train laparoscopic RFA skills on porcine liver tissue.

Evaluation of an online navigation system for laparoscopic interventions in a perfused ex vivo artificial tumor model of the liver.

BACKGROUND: Laparoscopic radiofrequency ablation (RFA) is a safe and effective method for tumor destruction in patients with unresectable liver tumors. However, accurate probe placement using laparoscopic ultrasound guidance is required to achieve complete tumor ablation. After evaluation of an ultrasound navigation system for transcutaneous and open RFA, we now intend to transfer this technique to laparoscopic liver surgery. This study aimed to evaluate an electromagnetic navigation system for laparoscopic interventions using a perfusable ex vivo artificial tumor model. MATERIALS AND METHODS: First a special adapter was developed to attach the ultrasound and electromagnetic tracking-based navigation system to a laparoscopic ultrasound probe. The laparoscopic online navigation system was studied in a laparoscopic artificial tumor model using perfused porcine livers. Artificial tumors were created by injection of a mixture of 3% agarose, 3% cellulose, and 7% glycerol, creating hyperechoic lesions in ultrasound. RESULTS: This study showed that laparoscopic ultrasound-guided navigation is technically feasible. Even in cases of angulation of the ultrasound probe no disturbances of the navigation system could be detected. Artificial tumors were clearly visible on laparoscopic ultrasound and not felt during placement of the RFA probe. Anatomic landmarks and simulated 'tumors' in the liver could be reached safely. DISCUSSION: Laparoscopic RFA requires advanced laparoscopic ultrasound skills for accurate placement of the RFA probe. The use of an ultrasound-based, laparoscopic online navigation system offers the possibility of out-of-plane needle placement and could increase the safety and accuracy of punctures. The perfused artificial tumor model presented a realistic model for the evaluation of this new technique.

Influence of operator experience in radiofrequency ablation of malignant liver tumours on treatment outcome.

AIMS: Radiofrequency ablation is gaining popularity as the interventional therapy of choice for unresectable hepatic malignancies. However, little attention has been paid to the importance of operator experience in this therapy. This study aims to evaluate the results of RFA treatment dependent on operator experience and learning curve. PATIENTS AND METHODS: Between 2/2000 and 11/2004 we have undertaken 116 RFA procedures to ablate 404 unresectable primary or metastatic liver tumours in 84 patients. The clinical data of all patients were recorded prospectively and treatment results of the first 42 patients (group I) and the second 42 patients (group II) were compared. All patients were treated by the same surgeon or interventional radiologist. RESULTS: RFA was performed percutaneously in 44 procedures (group I n = 35, group II n = 9), via laparotomy in 64 procedures (group I n = 27, group II n = 37) and via laparoscopy in eight procedures (group I n = 1, group II n = 7). The complication rate was comparable in both groups with 7.9% in group I and 7.5% in group II. Group II had a higher complete ablation rate (96.2 vs 93.7%) than group I. One- and two-year survival rates of 92 and 89% in group II were significantly higher than in group I with 69 and 46% (p = 0.015). CONCLUSION: By the experience conditional optimization of indication and performance by a specialized RFA team the results could be improved significantly. The data on hand speak for a considerable learning curve in the RFA and demonstrate the importance of the experience of the therapist for the outcome of the patients.

Two types of aggression are differentially related to serotonergic activity and the A779C TPH polymorphism.

The authors investigated whether different types of aggression relate to the A779C tryptophan hydroxylase (TPH) polymorphism and to serotonergic activity in volunteers. A factor analysis of the Buss-Durkee Hostility Inventory yielded 2 factors representing Neurotic Hostility (NH) and Aggressive Hostility (AH). The authors used a neuroendocrine challenge with Citalopram in 48 volunteers and increased cortisol concentrations only in those with high levels of AH. Finally, an association study with 58 volunteers revealed that the A779C TPH polymorphism significantly relates to AH, with the highest aggression levels for the genotype AA and the lowest aggression levels for the genotype CC, but not to NH. Results are discussed with respect to inconsistent findings in the literature, which may be explained by this distinction of types of aggression.

Uretero-iliac artery fistula--a rare cause of massive hematuria.

Uretero-arterial fistulae are rare. Immediate diagnosis and treatment are crucial in this life-threatening disorder and thus a uretero-arterial fistula in a patient with persistent hematuria should be taken into consideration. The authors report a case of a fistula between the right ureter and right common iliac artery.

Immunoassay methods for paralytic shellfish poisoning toxins.

The current status of immunochemical techniques for analysis of paralytic shellfish poisoning (PSP) toxins is summarized. Important aspects regarding production of the biological reagents necessary for immunochemical methods, the characteristics of polyclonal and monoclonal antibodies against saxitoxin and neosaxitoxin, and the importance of test sensitivity and specificity are discussed. Applications of immunochemical techniques for PSP toxins include microtiter plate enzyme immunoasays and enzyme-linked immunofiltration assays for toxin detection, and immunoaffinity chromatography (IAC) for sample extract cleanup. A major advantage of enzyme immunoassay (EIA) is simplicity and rapidity of the test procedure, and higher sensitivity than other methods. However, quantitative agreement between EIA and mouse bioassay is dependent on antibody specificity and the toxin profile in the shellfish; thus, both over- and underestimation of total toxicity may occur. For screening purposes, however, EIAs offer major advantages over the mouse bioassay, which is criticized in Europe because of animal welfare. A major application of antibodies against PSP toxins is their use for extract cleanup by IAC, which gives highly purified extracts, thereby enhancing determination of PSP toxins by conventional physicochemical methods such as liquid chromatography. IAC can also be used to isolate PSP toxins for preparation of analytical standard solutions.