A broad tuneable birdcage coil for mouse 1H/19F MR applications.

In this paper, we present the design and implementation of a 1H/19F volume coil for mouse body magnetic resonance (MR) imaging and spectroscopy using a high magnetic field (4.7 T). By changing the geometry of the coil rungs to include both nuclei for MR experiments, this innovative coil can be tuned over an extremely wide range of frequency. The coil, 45 mm in diameter and 55 mm in length, consists of a 12-rung birdcage-like structure. Using two types of tuning, the coil can generate a sufficiently homogeneous B1+ electromagnetic field within a working volume optimized for laboratory mouse. The first tuning involves changing the resonance frequency over a large frequency range. The electrical capacitance between the wires can be adjusted to reflect changes in the length of the coil. The second tuning comprises a habitual tuning transformer for precise detection in a narrow band. In contrast to widely used multinuclear coils, the coil presented here features only one resonance peak and can be manipulated according to the Larmor frequencies given for 1H and 19F. The coil was successfully tested using full-wave simulations of magnetic and electric field distributions under in vivo MR conditions.

A water-soluble, bay-functionalized perylenediimide derivative - correlating aggregation and excited state dynamics.

The aggregation and the photophysics of a water soluble perylenediimide (PDI) derivative that features two bromine substituents in the bay positions has been probed. Non-fluorescent aggregates were found to be present at concentrations of 1.0 × 10-5 M. In situ small-angle X-ray scattering (SAXS) measurements and complementary molecular modeling showed the presence of PDI aggregates. In their singlet excited states, the PDI aggregates are characterized by distinct transient fingerprints and rapid deactivation, as revealed by pump-probe experiments on the femto-, pico-, nano-, and microsecond timescales. The product of this deactivation is a PDI triplet excited state. The efficiency of the triplet formation depends on the concentration, and hence on the degree of aggregation. Notably, for PDI concentrations in the range of the critical micelle concentration, the efficiency of intersystem crossing is close to zero. In short, we have demonstrated, for the first time, aggregation-induced formation of triplet excited states for PDI derivatives.

[Operative Treatment for Saddle-Shaped Femoral Heads]. / Operacní resení sedlovité deformity hlavice kosti stehenní.

PURPOSE OF THE STUDY A saddle-shaped deformity of the femoral head has a poor prognosis due to rapid development of secondary changes. A new method of treatment by intra-articular anteromedial wedge reduction osteotomy (AWRO) of the femoral head may preserve the hip for the future. This study was designed to ascertain that this invasive technique was safe and effective and to confirm our hypothesis that AWRO significantly improved functional and radiological parameters of the hip joint. MATERIAL AND METHODS Patients who underwent AWRO between 2010 and 2013 were enrolled in this study. The indication criteria for the procedure included Stulberg grade V hips on AP radiographs, hinged abduction with pain, limping and a limited range of movement. Values of the Stulberg grading, capital diaphyseal index, caput-collum-diaphyseal angle and Harris hip score were recorded before and after surgery and the results were statistically evaluated using the paired t-test. The AWRO procedure was performed from the anterolateral approach after subperiosteal protection of the vessels had been ensured. The central necrotic part of the femoral head was removed, and the medial segment was mobilised and fixed to the intact lateral segment. Either a hip spica cast or bed-rest for six weeks was indicated. Full weight bearing was allowed at 3 months after surgery. RESULTS Twelve patients with an average follow-up of 55 months were evaluated. There were eight boys and four girls with an average age of 14 years at the time of surgery. The average Harris hip score improved from 54.52 before to 73.58 after surgery. The post-operative outcomes according to the Stulberg classification included one grade II hip, seven grade III hips, three grade IV hips and one grade V hip. The average capital-diaphyseal index dropped from 1.56 (1.19-1.92) to 1.28 (0.95-1.67) and the average caput-collum-diaphyseal angle increased from 134 degrees (121-143) to 140 degrees (130-155) after surgery. Avascular necrosis developed in two patients. All the differences were statistically significant. DISCUSSION Reduction osteotomies of the femoral head reported in the literature differ from the AWRO procedure used in this study in both the approach and the performance. The results presented here are in agreement with those published in the relevant literature. They showed no significant deterioration in comparison with the outcomes of our short-term study reported earlier. The outcome of treatment is related to the disease aetiology, functional parameters and previous procedures involving the hip joint. CONCLUSIONS AWRO is a salvage procedure that prolongs the longevity of joints in incongruent hips with very high morbidity. This procedure gave significantly better results in years after surgery, which confirmed our hypothesis. Level of evidence IV Key words: hinge abduction, Perthes disease, Stulberg, femoral head reduction osteotomy, avascular necrosis, arteria circumflexa femoris medialis.

A reliable risk score for stage IV esophagogastric cancer.

BACKGROUND: The role of surgery for patients with metastatic esophagogastric adenocarcinoma (EGC) is not defined. The purpose of this study was to define selection criteria for patients who may benefit from resection following systemic chemotherapy. METHODS: From 1987 to 2007, 160 patients presenting with synchronous metastatic EGC (cT3/4 cNany cM0/1 finally pM1) were treated with chemotherapy followed by resection of the primary tumor and metastases. Clinical and histopathological data, site and number of metastases were analyzed. A prognostic score was established and validated in a second cohort from another academic center (n = 32). RESULTS: The median survival (MS) in cohort 1 was 13.6 months. Significant prognostic factors were grading (p = 0.046), ypT- (p = 0.001), ypN- (p = 0.011) and R-category (p = 0.015), lymphangiosis (p = 0.021), clinical (p = 0.004) and histopathological response (p = 0.006), but not localization or number of metastases. The addition of grading (G1/2:0 points; G3/4:1 points), clinical response (responder: 0; nonresponder: 1) and R-category (complete:0; R1:1; R2:2) defines two groups of patients with significantly different survival (p = 0.001) [low risk group (Score 0/1), n = 22: MS 35.3 months, 3-year-survival 47.6%); high risk group (Score 2/3/4) n = 126: MS 12.0 months, 3-year-survival 14.2%]. The score showed a strong trend in the validation cohort (p = 0.063) [low risk group (MS not reached, 3-year-survival 57.1%); high risk group (MS 19.9 months, 3-year-survival 6.7%)]. CONCLUSION: We observed long-term survival after resection of metastatic EGC. A simple clinical score may help to identify a subgroup of patients with a high chance of benefit from resection. However, the accurate estimation of achieving a complete resection, which is an integral element of the score, remains challenging.

Preoperative therapy of esophagogastric cancer: the problem of nonresponding patients.

INTRODUCTION: Preoperative treatment is nowadays standard for locally advanced esophagogastric cancer in Europe. Surprisingly, little attention has been paid to nonresponders so far. The aim of our retrospective exploratory study was the comparison of responder, nonresponder, and primary resected patients in respect of outcome considering the tumor entity. PATIENTS AND METHODS: From 2001-2011, 607 patients with locally advanced esophagogastric carcinoma (adenocarcinoma of the esophagogastric junction (AEG), n = 293; squamous cell cancer (SCC), n = 111; gastric cancer, n = 203) after preoperative treatment (n = 281) or primary resection (n = 326) were included. Histopathological response evaluation (Becker criteria) was available for 263. RESULTS: A total of 76/263 (28.9 %) were responders (<10 % residual tumor). There was an association of response with increased R0 resections (p < 0.001) but also with a higher complication rate (p = 0.008) compared to nonresponse and primary surgery. Mortality was not influenced. Increased R0 resections after response were confirmed in every tumor entity (AEG, p = 0.010; SCC, p = 0.023; gastric cancer, p = 0.006). Median survival was best for responders with 43.5 months [95 % confidence interval (CI), 27.9-59.1], followed by nonresponders with 24.3 months (95 % CI, 21.6-27.0) and primary resected patients with 20.8 months (95 % CI, 17.7-23.9; p = 0.002). AEG (p = 0.012) and gastric cancer (p = 0.017) revealed identical results, but in the subgroup of SCC, the survival of nonresponders (median, 11.6 months; 95 % CI, 6.9-16.3) was even worse than for primary resected patients (median, 23.8 months; 95 % CI, 1.7-46.0; p = 0.012). CONCLUSION: The histopathological response rate was low. Generally, nonresponding patients with AEG or gastric cancer seem not to have a disadvantage compared to primary resected patients, but nonresponders with SCC have a worse prognosis, which strengthens the demand for a critical patient selection in surgery for this tumor entity.

Expression of staphylococcal superantigens during nasal colonization is not sufficient to induce a systemic neutralizing antibody response in humans.

Staphylococcus aureus carriers have high-titer serum antibodies against non-enterotoxin gene cluster (egc) superantigens, whereas they lack anti-egc antibodies, suggesting different superantigen expression profiles in vivo. We measured the superantigen transcripts in S. aureus directly isolated from the nose of persistent carriers and correlated them with the superantigen-neutralizing antibody response. While neutralizing serum antibodies against the staphylococcal enterotoxins A and C (SEA and SEC) were found in carriers, antibodies against the egc-encoded staphylococcal enterotoxin-like toxin O (SElO) were rare. Surprisingly, the transcription of selo was comparable to sea and sec during nasal colonization. Thus, egc superantigens are transcribed during nasal colonization, but this is not sufficient to induce a serum antibody response.

Piezosurgery prevents brain tissue damage: an experimental study on a new rat model.

Piezosurgery is a promising meticulous system for bone cutting, based on ultrasound microvibrations. It is thought that the impact of piezosurgery on the integrity of soft tissue is generally low, but it has not been examined critically. The authors undertook an experimental study to evaluate the brain tissue response to skull bone removal using piezosurgery compared with a conventional drilling method. In Wistar male rats, a circular bone window was drilled to the parietal bone using piezosurgery on one side and a conventional bone drill on the other side. The behavioural performance of animals was evaluated using the motor BBB test and sensory plantar test. The brains of animals were evaluated by magnetic resonance imaging (MRI) and histology. The results of MRI showed significantly increased depth and width of the brain lesion in the region of conventional drilling compared with the region where piezosurgery was used. Cresylviolet and NF 160 staining confirmed these findings. There was no significant difference in any of the behavioural tests between the two groups. In conclusion, piezosurgery is a safe method for the performance of osteotomy in close relation to soft tissue, including an extremely injury-sensitive tissue such as brain.

[Efficiency of conservative treatment by overhead traction in developmental dysplasia of the hip]. / Úspesnost konzervativní lécby vývojové kycelní dysplazie metodou "over-head trakce"

PURPOSE OF THE STUDY: Developmental dysplasia of the hip (DDH) is a disorder affecting the development of the acetabulum, proximal femur and joint capsule. The objective of this study was to analyse the results of closed reduction by overhead traction in subluxated and dislocated hips. MATERIAL AND METHODS: In the period from 2002 to 2007, a total of 109 patients (124 hips) were treated by overhead traction. The indication criteria included adductor contracture and misalignment of the hip joint assessed as classes III A, III B or IV according to the Graf ultrasonographic classification. There were 96 (88 %) girls and 13 (12 %) boys. The left side was more frequently affected, at a ratio of 83 to 41, and bilateral DDH was found in 15 patients. Teratologic dislocations were not included in the study. The patients were divided into two groups according to age and the place of primary diagnosis. The children primarily diagnosed at our hospital Na Bulovce where placed in group 1, the patients diagnosed outside our hospital fell in group 2. The average age at the beginning of treatment was 2.2 months in the first group and 6 months in the second group. Our method of overhead traction consists of two phases. Horizontal traction is applied for two weeks in phase 1; the hips are then flexed beyond 90 degrees and gradually abducted for another 4 weeks in phase 2.The outcome of traction is examined by arthrography and a spica cast is applied in the safe zone.We observed the relation between the Graf classification and arthrograpy. The outcome of closed reduction was compared between the groups and the development of avascular necrosis was observed. The hips treated by open reduction were assessed in a different study. RESULTS The efficiency of closed reduction was 84 % in group 1 and 60 % in group 2 in which also two cases of recurrent dislocation were found. No significant differences between the Graf classification and the final arthrographic findings were recorded in either group (p ≥ 0.05). Avascular necrosis as defined by the Salter criteria was not diagnosed. DISCUSSION: Early reduction is essential to ensure normal development of the hip joint. Overhead traction therapy for misalignment of the hip joint is a safe method reducing damage to the femoral head. Its principle lies in gradual distraction of the contracted muscles and joint capsule with a concomitant change in traction direction in order to achieve a reduction manoeuvre without placing increased stress on the femoral head. CONCLUSIONS: Overhead traction is the method of choice for management of Graf's class III A, III B and IV hips. For the efficiency of treatment, an early diagnosis and a correct indication are essential. To avoid complications such as avascular necrosis, it is necessary to observe the principle of a safe zone.

Microcirculation of subepithelial gastric tumors using contrast-enhanced ultrasound.

OBJECTIVES: The evaluation of subepithelial tumors of the stomach is normally the domain of gastroscopy and endoscopic ultrasound. We investigated these rare tumors using transabdominal B-mode ultrasound and performed perfusion analysis of these tumors with contrast enhanced ultrasound. METHODS: Patients with gastrointestinal stromal tumors (GIST, n = 3), leiomyoma (n = 1) and schwannoma (n = 1) were routinely examined using conventional B-mode-ultrasound, colour Doppler ultrasound and contrast-enhanced ultrasound (contrast media: Sonovue; ultrasound device: Siemens Acuson Sequoia 512). Gastroscopy, endosonography with puncture of the subepithelial tumor and computed tomography were also performed in all patients. After surgery, the resected stomach tumors were correlated with the preoperative imaging findings. RESULTS: All calculated tumor sizes using any imaging modalities showed a good correlation with the macroscopic tumor sizes ex-vivo. Histologically increased tumor size of the GISTs was correlated with large, central avascular areas. The GISTs and the leiomyoma presented with mixed echogenicity in B-mode-ultrasound. Colour Doppler ultrasound was able to detect some vessels in the periphery of the tumor only. Using contrast-enhanced ultrasound the GISTs and the leiomyoma presented hypervascular. The contrast pattern of these lesions was from the periphery to the centre or diffuse or a progressive centrifugal fill in during the arterial phase. We also registered slowly progressive washout starting at the end of the arterial phase and increasing into the late phase. The contrast media behaviour in the schwannoma was different from that describt above within the GISTs: it was noted to have a diffuse intralesional pattern at the start of the arterial phase followed by an early, rapidly progressing washout-phenomenon. CONCLUSION: In our pilot study B-mode transabdominal ultrasound was able to visualise gastric subepithelial tumors larger than three centimetre. Contrast-enhanced ultrasound is a proven method in clinical practice for the perfusion analysis of gastric subepithelial tumors. It can also be used for the planning of ultrasound-guided biopsies to avoid punctures of necrotic tumor parts.

Core-shell La(1-x)Sr(x)MnO3 nanoparticles as colloidal mediators for magnetic fluid hyperthermia.

Core-shell nanoparticles consisting of La(0.75)Sr(0.25)MnO(3) cores covered by silica were synthesized by a procedure consisting of several steps, including the sol-gel method in the presence of citric acid and ethylene glycol, thermal and mechanical treatment, encapsulation employing tetraethoxysilane and final separation by centrifugation in order to get the required size fraction. Morphological studies revealed well-separated particles that form a stable water suspension. Magnetic studies include magnetization measurements and investigation of the ferromagnetic-superparamagnetic-paramagnetic transition. Magnetic heating experiments in 'calorimetric mode' were used to determine the heating efficiency of the particles in water suspension and further employed for biological studies of extracellular and intracellular effects analysed by tests of viability.

Simultaneous use of laparoscopy and endoscopy for minimally invasive resection of gastric subepithelial masses - analysis of 93 interventions.

BACKGROUND: Subepithelial gastric tumors are common findings during upper gastrointestinal endoscopy. Tumor resection is mostly done laparoscopically, but there is still discussion concerning the size of lesion for which the treatment may be minimally invasive; additionally there is very little data available concerning patient outcome after minor access surgery. METHODS: Clinicopathologic features and survival data of 93 consecutive patients undergoing a combined laparoscopic-endoscopic approach for gastric submucosal tumors were prospectively analyzed. Analysis included preoperative diagnostic work-up, perioperative data, and postoperative complications. Follow-up was carried out for patients with GIST to check for tumor recurrence. RESULTS: It was possible to resect 88 of 93 lesions by the laparoscopic-endoscopic approach, with tumor-free margins in all patients. Intraoperative endoscopy facilitated exact tumor localization in 92 patients. Most lesions were removed by endoscopic-laparoscopic wedge resection or, less frequently, by a combined transgastric approach. Mean operative time was 90.7 min; the postoperative hospitalization was 7.3 days. Adverse events appeared in 7.5%, and conversion to open surgery was required in 6.5%. For patients suffering from gastrointestinal stromal tumors, there was no tumor recurrence at a mean follow-up of 40 months. CONCLUSIONS: Combined laparoscopic-endoscopic "rendez-vous" procedures are easy to perform and offer a curative approach for almost all gastric submucosal lesions. The technique is associated with low morbidity and short hospitalization. Though even patients with large GISTs of intermediate and high risk were treated, no tumor recurrence has been observed to date.

[Rare occurrence of fulminant acid burn of the esophagus]. / Seltene Ursache einer fulminanten Säureverätzung des Osophagus.

Peptic ulcer due to Zollinger-Ellison syndrome is a rare entity. In this case report a 55-year-old man had a medical history of esophageal reflux, vomiting, and diarrhea for 10 years. Despite continuous medication with a proton pump inhibitor, no complete recovery from symptoms was achieved. A diagnosis of gastrinoma was at first not considered. After discontinuation of the proton pump inhibitor for only a few days, the strong stimulation of the gastrinoma led to fulminant hydrochloric acid burn of the distal esophagus with iatrogenic or spontaneous perforation at the esophagogastral junction. We describe the operative treatment as a two-stage reconstruction with colon interposition and resection of the primary tumor in the duodenum.

Development, standardization, and evaluation of NOTES cholecystectomy using a transsigmoid approach in the porcine model: an acute feasibility study.

BACKGROUND: Transluminal cholecystectomy is feasible. However, the procedure is time consuming, difficult, and poorly standardized so far. In the present study we therefore aimed to further evaluate and optimize a transsigmoid approach for cholecystectomy with minimal transabdominal assistance in the porcine model. METHODS: After a pilot series of 6 pigs, NOTES (natural-orifice transluminal endoscopic surgery) cholecystectomy was performed in a standardized manner in another 12 pigs. A transsigmoid approach was applied via a specially designed trocar (ISSA) with a double-channel gastroscope advanced into the peritoneal cavity. After identification of the infundibulum, the cystic duct and artery were closed by application of hemostasis clips. After dissection of these structures, the gallbladder was separated from the liver by electrocautery following injection of isotonic saline solution. A grasper introduced through a modified Veress needle (initially used for establishing the hydroperitoneum) and an additional transcutaneous stay suture were used to ease preparation of the gallbladder. RESULTS: Transluminal cholecystectomy was successfully performed in all animals. No serious acute complications occurred; minor bleeding in 4 out of 12 cases (1 cystic artery and 3 liver parenchyma) was successfully handled by electrocautery. Clip application to close the cystic duct and artery resulted in complete sealing. Standardization of the procedure was associated with a significant decrease in total operating time (113.3 +/- 31.8 minutes for the first 6 pigs and 73.6 +/- 17.2 minutes for the last 6 pigs). CONCLUSIONS: In pigs with a healthy gallbladder, our standardized technique of transsigmoid cholecystectomy could be performed relatively fast with acceptable complication rates at this level of evolution, as shown in these acute experiments.

Squamous cell carcinoma and Zenker diverticulum.

Squamous cell carcinoma in a Zenker diverticulum is a very rare condition. We report a case of a patient with a Zenker carcinoma, who was primarily functionally inoperable and therefore received neoadjuvant radiochemotherapy before cardiac bypass surgery. After a complicated course with cardiogenic shock and myocardial infarction, a re-evaluation of functional risk analysis and the tumor situation revealed operability. Subsequently, partial hypopharyngectomy and partial cervical esophageal resection with lymphadenectomy was performed. Reconstruction of the gastrointestinal continuity was made by interposition of a free small bowel graft and microvascular anastomosis. The postoperative course showed a small anastomotic leakage of the hypopharyngeal-small bowel anastomosis, which was successfully treated conservatively.

Salvage therapy with oral etoposide in recurrent and/or metastatic squamous cell carcinoma of the head and neck.

BACKGROUND: The purpose of this retrospective evaluation was to assess the palliative effect of oral etoposide in heavily pretreated patients with squamous cell carcinoma of the head and neck. PATIENTS AND METHODS: Between October 1995 and February 2003, a total of 26 patients with metastatic and/or recurrent squamous cell carcinoma of the head and neck (SCCHN) were treated with oral etoposide. Therapy consisted of etoposide at a total dose of 100 mg daily for 7 days and was repeated every 4 weeks until progression of disease or for a maximum of 8 courses. Eighteen patients underwent primary surgery of the tumour followed by adjuvant irradiation or surgery after neoadjuvant radiochemotherapy. Eight patients had primary irradiation with or without concomitant chemotherapy. All patients previously received at least one palliative chemotherapy with cisplatin/5-floururacil (5-FU) or cisplatin/taxotere. Patients did not routinely receive anti-emetic medication. RESULTS: All patients were eligible for toxicity and survival assessment, and 24 of 26 patients for response evaluation according to an intention-to-treat principle. Two patients had a partial response (8 percent); disease was stable in 9 patients (35 percent) and progressed in 13 patients (50 percent). The median time to progression for all patients was 3 months (range, 2-54), and median overall survival was 10 months (range, 2-52). Toxicity was in general mild and moderate (Grade 1 and 2), except three patients, who experienced Grade 3 anaemia, and one patient who had Grade 3 thrombocytopenia without bleeding complications. Severe nonhematologic adverse reactions were not seen, except for alopecia. CONCLUSION: Our data suggest that oral etoposid is markedly effective, in regard to stabilization of disease and survival, and an excellent tolerated therapy for pretreated patients with recurrent and/or metastatic head and neck carcinomas. Its advantage over other commonly used and more intensive regimens such as 5-fluorouracil (5-FU) + cisplatin or taxane-containing combinations is its superior tolerance, in particular the incidence of nausea and vomiting, complete alopecia, and/or hematologic complications.

Superimposed high-frequency jet ventilation (SHFJV) for endoscopic laryngotracheal surgery in more than 1500 patients.

BACKGROUND: Superimposed high-frequency jet ventilation (SHFJV), which does not require any tracheal tubes or catheters, was developed specifically for use in laryngotracheal surgery. SHFJV uses two jet streams with different frequencies simultaneously and is applied in the supraglottic space using a jet laryngoscope and jet ventilator. METHODS: Between 1990 and 2004, SHFJV was studied in 1515 consecutive patients (including 158 children requiring laryngotracheal surgery) prospectively. Ventilation was performed with an air/oxygen mixture and anaesthesia was administered i.v. RESULTS: Adequate oxygenation and ventilation was achieved in 1512 patients. Arterial blood gas analyses (BGA) were performed between 1990 and 1994; thereafter BGA was only performed in patients with high-grade stenosis of the larynx/trachea or high-risk patients [n=623, mean Pa(O(2)) 133.8 (39.4) mm Hg and mean Pa(CO(2)) 42.3 (10.1) mm Hg]. There were no significant changes in Pa(O(2)) or Pa(CO(2)) during the entire period of SHFJV. No complications secondary to the ventilation technique were observed; in particular, no barotrauma occurred. Three patients required tracheal intubation. SHFJV was also successfully used for laser surgery (n=312). It proved to be a safe mode of ventilation without any complications such as airway fire, major haemorrhage, or aspiration of debris. CONCLUSION: SHFJV is an advanced ventilation mode playing a pivotal role in the (open) ventilatory support/ventilation of patients with laryngotracheal stenosis. It is particularly indicated in cases of severe stenosis and offers optimal conditions for laryngotracheal surgery, including laser surgery and stent implantation techniques.

Nickel release, a possible indicator for the duration of antiplatelet treatment, from a nickel cardiac device in vivo: a study in patients with atrial septal defects implanted with an Amplatzer occluder.

UNLABELLED: The present study was undertaken to evaluate the safety and release of nickel after implantation of a nickel device (Amplatzer occluder) in patients with an atrial septal defect (ASD) receiving antiplatelet therapy. METHODS: Blood and urine samples were obtained from 24 patients with ASD before occluder implantation (baseline) and during a 12-month post closure period. Antiplatelet drugs were administered for the initial 6-month period post implantation. The nickel content in the specimens was determined using electrothermal atomic absorption spectroscopy. The clinical, sonographic and magnetic resonance imaging follow-ups were carried out 1 week, 1 month, 6 months and 12 months post implantation. RESULTS: Mean baseline concentrations of nickel in serum and urine were within normal range with values of 0.6 +/- 0.2 microg/l and 3.1 +/- 1.2 microg/l, respectively. During the 6-week post closure period, the time needed for the formation of neointima on the surface of the graft, nickel levels in serum increased up to 5-fold (p < 0.01 versus baseline). Mean concentrations in serum and urine returned to baseline levels within 4-6 months post implantation. All patients showed satisfactory clinical improvements and there was no sonographic evidence of complications. CONCLUSIONS: The initial dissolution of nickel from the Amplatzer occluder is not a specific cardiovascular risk and is temporarily linked to the formation of the non-thrombogenic neointima on the surface of the graft. The antiplatelet drug regimen used (300 mg aspirin + 75 mg clopidogrel daily for 3 months in the initial phase and 100 mg aspirin daily for a further 3 months) appears to cover the period of neointima formation on the nickel device when nickel levels are significantly elevated. However, further studies in a larger number of patients and over a period greater than 12 months are needed to confirm the validity of these conclusions and to formulate definitive recommendations on the duration of the antiplatelet treatment.

Linear microstrip surface coil for MR imaging of the rat spinal cord at 4.7 T.

A new design of RF coil based on a quasi-transverse electromagnetic field is described. The coil was developed for the acquisition of MR images of the rat spinal cord at 4.7 T. Different materials for the construction of the coil were tested, and the best results were obtained with Teflon. The design of the microstrip coil enables the investigator to change the length of the coil in a longitudinal direction and yields a relatively high signal-to-noise ratio due to the restricted field of view. Low RF field penetration depth also helps in suppressing motion artifacts generated by, e.g., breathing or heartbeats.

[Sentinel lymph node mapping in gastric and esophageal carcinomas]. / Sentinel Lymph Node beim Magen- und Osophaguskarzinom.

During the last 5 years, the concept of sentinel lymph nodes has been investigated in a variety of solid tumors. Despite the multidirectional and complex lymphatic drainage of the stomach, early gastric cancer has been shown to be a suitable model for sentinel lymph node mapping. In contrast, sentinel lymph node mapping of esophageal cancer is compromised by the anatomic location of the esophagus and its lymphatic drainage in the closed space of the mediastinum. The technique and clinical application of sentinel lymph node mapping thus differ between esophageal and gastric cancer. Reliable detection of sentinel lymph nodes in the mediastinum requires radioisotope labelling, while blue dye and radioisotope labelling are both feasible for gastric cancer. In patients with early gastric cancer, laparoscopic resection with sentinel node negative status is already under investigation in clinical trials. In esophageal cancer, sentinel node mapping is still considered an experimental technique. Preliminary data, however, indicate that it may be reliable and feasible in patients with early adenocarcinoma of the distal esophagus.

[Methods of sentinel lymph node mapping]. / Zur Methodik des Sentinel Lymph Node Mapping.

Sentinel lymph node mapping is used as a diagnostic method in order to increase staging accuracy without the well-known morbidities of radical lymphadenectomy. The sentinel node is defined as the first node to receive lymphatic drainage from a primary tumor. The sentinel node concept postulates that if the first draining node is negative for metastasis, the remaining lymph nodes in the nodal basin can be spared. Thus one can predict the status of the nodal basin with high accuracy. It also shows that lymphatic spread seems to follow certain rules that do not concern the whole lymphatic basin. Skip metastases were proven to be rare in breast and gastric cancer. The main issue in sentinel lymph node mapping remains the improvement of staging accuracy for detection of lymph nodes most likely to develop metastasis as well as reducing morbidity by planning lymphadenectomies individually for each tumor and each patient.