Seasonal exposure of carbon dioxide ice on the nucleus of comet 67P/Churyumov-Gerasimenko.

Carbon dioxide (CO2) is one of the most abundant species in cometary nuclei, but because of its high volatility, CO2 ice is generally only found beneath the surface. We report the infrared spectroscopic identification of a CO2 ice-rich surface area located in the Anhur region of comet 67P/Churyumov-Gerasimenko. Spectral modeling shows that about 0.1% of the 80- by 60-meter area is CO2 ice. This exposed ice was observed a short time after the comet exited local winter; following the increased illumination, the CO2 ice completely disappeared over about 3 weeks. We estimate the mass of the sublimated CO2 ice and the depth of the eroded surface layer. We interpret the presence of CO2 ice as the result of the extreme seasonal changes induced by the rotation and orbit of the comet.

Exposed water ice on the nucleus of comet 67P/Churyumov-Gerasimenko.

Although water vapour is the main species observed in the coma of comet 67P/Churyumov-Gerasimenko and water is the major constituent of cometary nuclei, limited evidence for exposed water-ice regions on the surface of the nucleus has been found so far. The absence of large regions of exposed water ice seems a common finding on the surfaces of many of the comets observed so far. The nucleus of 67P/Churyumov-Gerasimenko appears to be fairly uniformly coated with dark, dehydrated, refractory and organic-rich material. Here we report the identification at infrared wavelengths of water ice on two debris falls in the Imhotep region of the nucleus. The ice has been exposed on the walls of elevated structures and at the base of the walls. A quantitative derivation of the abundance of ice in these regions indicates the presence of millimetre-sized pure water-ice grains, considerably larger than in all previous observations. Although micrometre-sized water-ice grains are the usual result of vapour recondensation in ice-free layers, the occurrence of millimetre-sized grains of pure ice as observed in the Imhotep debris falls is best explained by grain growth by vapour diffusion in ice-rich layers, or by sintering. As a consequence of these processes, the nucleus can develop an extended and complex coating in which the outer dehydrated crust is superimposed on layers enriched in water ice. The stratigraphy observed on 67P/Churyumov-Gerasimenko is therefore the result of evolutionary processes affecting the uppermost metres of the nucleus and does not necessarily require a global layering to have occurred at the time of the comet's formation.

Cometary science. The organic-rich surface of comet 67P/Churyumov-Gerasimenko as seen by VIRTIS/Rosetta.

The VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer) instrument on board the Rosetta spacecraft has provided evidence of carbon-bearing compounds on the nucleus of the comet 67P/Churyumov-Gerasimenko. The very low reflectance of the nucleus (normal albedo of 0.060 ± 0.003 at 0.55 micrometers), the spectral slopes in visible and infrared ranges (5 to 25 and 1.5 to 5% kÅ(-1)), and the broad absorption feature in the 2.9-to-3.6-micrometer range present across the entire illuminated surface are compatible with opaque minerals associated with nonvolatile organic macromolecular materials: a complex mixture of various types of carbon-hydrogen and/or oxygen-hydrogen chemical groups, with little contribution of nitrogen-hydrogen groups. In active areas, the changes in spectral slope and absorption feature width may suggest small amounts of water-ice. However, no ice-rich patches are observed, indicating a generally dehydrated nature for the surface currently illuminated by the Sun.

[Concept of an interdisciplinary emergency department at the Schwarzwald-Baar Hospital]. / Konzept einer interdisziplinären Notaufnahmeklinik am Schwarzwald-Baar Klinikum.

BACKGROUND: Numerous hospitals were combined years ago into a new Central Hospital for cost reasons in the Schwarzwald-Baar region. This also suggested the idea of a large central emergency department. The concept of a central emergency department is an organizational challenge, since they are directly engaged in the organizational structure of all medical departments that are involved in emergency treatment. Such a concept can only be enforced if it is supported by hospital management and all parties are willing to accept interdisciplinary and interprofessional work. OBJECTIVE: In this paper, the concept of a central emergency department in a tertiary care hospital which was rebuilt as an organizationally independent unit is described. Collaborations with various departments, emergency services, and local physicians are highlighted. The processes of a central emergency department with an integrated admission department and personnel structures are described. CONCLUSION: The analysis of the concept after almost a year has shown that the integration into the clinic has been successful, the central emergency department has proven itself as a central hub and has been accepted as a unit within the hospital.

The surface composition and temperature of asteroid 21 Lutetia as observed by Rosetta/VIRTIS.

The Visible, InfraRed, and Thermal Imaging Spectrometer (VIRTIS) on Rosetta obtained hyperspectral images, spectral reflectance maps, and temperature maps of the asteroid 21 Lutetia. No absorption features, of either silicates or hydrated minerals, have been detected across the observed area in the spectral range from 0.4 to 3.5 micrometers. The surface temperature reaches a maximum value of 245 kelvin and correlates well with topographic features. The thermal inertia is in the range from 20 to 30 joules meter(-2) kelvin(-1) second(-0.5), comparable to a lunarlike powdery regolith. Spectral signatures of surface alteration, resulting from space weathering, seem to be missing. Lutetia is likely a remnant of the primordial planetesimal population, unaltered by differentiation processes and composed of chondritic materials of enstatitic or carbonaceous origin, dominated by iron-poor minerals that have not suffered aqueous alteration.

Delays in diagnosis and therapy of gastric cancer and esophageal adenocarcinoma.

BACKGROUND AND STUDY AIMS: In the past, there were long delays in the diagnosis of patients with cancer of the stomach or esophagus. The objective of this study was to describe current delays in the diagnosis and treatment of gastric and esophageal adenocarcinoma and to compare the findings with those from an historical control population treated at the same institutions 10 years earlier. PATIENTS AND METHODS: Patients with biopsy-proven gastric cancer or esophageal adenocarcinoma who were treated at two academic medical centers in Germany between April and October 2003 were consecutively screened for eligibility to take part in the study. Medical charts for each patient were reviewed. Additional data were obtained via structured interviews. Main outcome measures were the total delay, and the delays related to patients themselves, to doctors, and to the hospital. Data were compared with those from a historic control group assessed in 1993. RESULTS: The median total delay for patients with gastric cancer (n = 104) was 3.5 months (range 0.3 - 29.6), and in patients with esophageal adenocarcinoma (n = 22) the total delay was significantly shorter (median 2.2 months, range 1.2 - 11.7; P < 0.05). Comparing these findings with those from an historic cohort of patients with gastric cancer (n = 100) revealed a significant decrease in the total delay (3.5 versus 8.0 months, P < 0.001). CONCLUSIONS: The current findings indicate that delays in the diagnosis and treatment of gastric cancer have become significantly shorter within the last 10 years as our understanding of and ability to treat this form of cancer have improved.

FDG PET and CT in locally advanced adenocarcinomas of the distal oesophagus. Clinical relevance of a discordant PET finding.

AIM: The incidence of adenocarcinomas of the distal oesophagus (ADE) has dramatically increased in Western countries. The clinical importance of a FDG PET finding discordant with CT was determined in patients with locally advanced ADE. In addition, tumour standardized uptake values (SUV) were correlated with patient survival. PATIENTS, METHODS: 40 consecutive patients were analyzed retrospectively. All patients underwent an attenuation corrected FDG PET scan (neck, chest, abdomen) and contrast enhanced helical CT of the chest and abdomen. PET and CT scans were reviewed independently and concomitantly with respect to metastases in predefined lymph node sites and organs. Any discordance between PET and CT was assessed for clinical relevance. Clinical relevance was defined as a change in the overall therapeutic concept (curative vs. palliative). Follow-up imaging and histological evaluation served as the gold standard. Mean tumour SUVs were determined by 1.5 cm regions of interest placed over the tumour's maximum. RESULTS: When read independently from the CT scan FDG PET indicated a clinically relevant change in tumour stage in 9/40 patients (23%) and a non-relevant change in 11/40 patients (28%). PET was correct in 5/9 patients (56%) with clinically relevant discordances. In 4/9 patients PET was incorrect (3 false positive due to suspicion of M1-lymph nodes or lung metastases, 1 false negative in disseminated liver metastases). With concomitant reading, PET indicated a clinically relevant change in tumour stage in 6/40 patients (15%) and a non-relevant change in 5/40 patients (13%). PET was correct in 5/6 patients (83%) with clinically relevant discordances. The patient with disseminated liver disease remained the single false negative. Overall, the benefit from PET was based on its higher diagnostic accuracy at organ sites. Tumour SUV did not correlate with patient survival. CONCLUSION: About half of discordances between FDG PET and CT are clinically relevant. Concomitant reading of PET and CT is advisable as it reduces the overall rate of discordances and enhances the accuracy of PET in clinical relevant discordances (from 56% to 83%).

Responders benefit from neoadjuvant radiochemotherapy in esophageal squamous cell carcinoma: results of a prospective phase-II trial.

BACKGROUND: We present the results of a prospective phase-II-study of neoadjuvant combined radiochemotherapy followed by surgical resection in patients with histological proven locally advanced squamous cell carcinoma of the esophagus located at or above the level of the tracheal bifurcation. METHODOLOGY: Between February 1995 and March 2000 a total of 76 patients with esophageal squamous cell carcinoma (uT3/4N0/+-categories) received simultaneous combined neoadjuvant radiochemotherapy consisting of a continuous intravenous infusion of 5-fluorouracil (300 mg/m2/day) 7 day per week concurrently with conventional fractioned external beam radiation therapy (2 Gy/day), five fractions per week up to a total dose of 30 Gy. RESULTS: Radiochemotherapy related acute severe toxicity rate (CTC-grade-III) occurred in 34 patients, two patients died. Sixty-four patients underwent surgery with a complete resection in 48 patients. Three patients died during a 90-day post-operative course. The histopathological workup revealed no viable residual tumour cells in eight patients (ypCR) and according to the modified criteria of Mandard in 26 patients a histopathological response. Twenty-two of these patients underwent a R0-resection. The median follow-up time was 5.4 years with an overall median survival time of 20.6 months. The median survival in the 26 responders was 32.3 months versus 19.5 months in 38 non-responders (p=0.03). CONCLUSIONS: Patients with locally advanced squamous cell carcinoma of the esophagus, who respond to preoperative neoadjuvant combined radiochemotherapy, seem to have more benefit from subsequent resection than non-responding patients.

Recurrent arachnoid cyst of Meckel's cave mimicking a brain stem ischaemia. Report of a rare case.

UNLABELLED: A 44-years old man developed TIA-like symptoms with dysaesthesia around the mouth, vertigo and diplopia. MRI revealed a cystic space-occupying lesion on the right Meckel's cave, which spread out into cerebellopontine angle in a further examination. Therefore surgical exploration was performed using a suboccipital approach. An arachnoidal cyst was found and removed including its wall. About three months later the patient suffered again from dysaesthesias of the right side of the face and a new MRI revealed a recurrence of the lesion, with extension into the cerebellopontine angle, too. Surgical revision was done using the same approach and the recurrent cyst was removed. Postoperatively, there were a transient hypaesthesia in the distribution area of the right trigeminal nerve and a light pulmonary embolism occurred as a complication. No symptoms have returned during an observation period of 15 months. CONCLUSION: An arachnoidal cyst must be considered as a rare cause, when a lesion is found at the Meckel's cave with intermittent clinical symptoms of a trigeminal nerve affection. As surgical treatment we favour fenestration and cyst wall resection.

[Neoadjuvant therapeutic principles guided by response prediction and evaluation]. / Neoadjuvante Therapieprinzipien orientiert an Responseprädiktion und Evaluation.

Only patients with a clinical and pathohistological response to neoadjuvant therapy have a significantly improved survival. Therefore the identification of predictors for response and procedures for the early identification of nonresponders appear to be mandatory. Preliminary data of biochemical investigations of target enzymes for several cytostatics (e.g. TS, ERCC1) appear to be promising. Early changes of the tumor metabolism in the FDG-PET enable the identification of nonresponders with a negative predictive value of 88-95%. In near future these findings should lead to consequences in the design and realization of clinical studies.

[Monitoring of response to neoadjuvant therapy by positron emission tomography (PET)]. / Responseevaluation durch Positronenemissionstomographie (PET) im Rahmen der neoadjuvanten Therapie.

Neoadjuvant therapy is frequently hampered by the lack of reliable non-invasive techniques for prediction and assessment of response. Positron emission tomography using the glucose analogue 18F-fluorodeoxyglucose (FDG-PET) provides a unique means of non-invasive assessment of tumor metabolism. Several recent studies have indicated that a reduction of tumor metabolic activity after neoadjuvant therapy is closely correlated with the degree of histopathological tumor regression. The reduction of metabolic activity may also allow one to predict subsequent response early during the course of therapy. Therefore FDG-PET may permit individualized therapy management. However, there is a requirement for larger-scale trials to assess this technique.

Histologic tumor type is an independent prognostic parameter in esophageal cancer: lessons from more than 1,000 consecutive resections at a single center in the Western world.

OBJECTIVE: To analyze the changing pattern in tumor type and postoperative deaths at a national referral center for esophageal cancer in the Western world and to assess prognostic factors for long-term survival after resection. SUMMARY BACKGROUND DATA: During the past two decades, the epidemiology and treatment strategies of esophageal cancer have changed markedly in the Western world. The influence of these factors on postoperative deaths and long-term prognosis has not been adequately evaluated. METHODS: Between 1982 and 2000, 1,059 patients with primary esophageal squamous cell cancer or adenocarcinoma had resection with curative intention at a single center. Patient and tumor characteristics and details of the surgical procedure and outcome were documented during this period. Follow-up was available for 95.8% of the patients. Changing patterns in tumor type and postoperative deaths were analyzed. Prognostic factors for long-term survival were assessed by multivariate analysis. RESULTS: The prevalence of adenocarcinoma in patients with resected esophageal cancer increased markedly during the study period. The postoperative death rate decreased from about 10% before 1990 to less than 2% since 1994, coinciding with the introduction of a procedure-specific composite risk score and exclusion of high-risk patients from surgical resection. In addition to the well-established prognostic parameters, tumor cell type "adenocarcinoma" was identified as a favorable independent predictor of long-term survival after resection. The independent prognostic effect of tumor cell type persisted in the subgroups of patients with primary resection and patients with primary resection and R0 category. CONCLUSION: Esophagectomy for esophageal cancer has become a safe procedure in experienced hands. Esophageal adenocarcinoma has a better long-term prognosis after resection than squamous cell carcinoma.

Proliferation kinetics and prognosis in gastric cancer after resection.

The influence of proliferation and proliferation kinetics on prognosis in gastric cancer after complete resection are controversial. In a prospective study we investigated the tumour specimens of 111 patients after resection of gastric cancer, who received 200 mg intravenous (i.v.) bromodeoxyuridine (BrdU) pre-operatively. The following biological parameters were analysed in the tumour tissue using flow-cytometry: DNA ploidy, proportion of S-phase cells, BrdU labelling index (LI), DNA synthesis time (T(s)), potential tumour doubling time (T(pot)), proliferating cell nuclear antigen (PCNA) and Ki-67 LI. The median follow-up time was 40 months (range 19-62 months). Besides the established pathohistological prognostic factors, univariate analysis revealed a prognostic influence on survival for BrdU LI, T(pot) and the proportion of S-phase cells. By multivariate Cox analysis of the completely resected cases, only tumour stage and T(pot) had a significant, independent influence on survival. By classification and regression trees (CART) analysis, resection status, tumour stage and T(pot) defined risk groups with significantly different outcomes. A short T(pot) was a predictor of better survival in stage I, II and IIIA tumours. Ploidy and the other investigated proliferation-related parameters failed to demonstrate any influence on prognosis after resection of gastric cancer.

A new method for surgical repair of impression fractures of the cranial vault and frontal sinus with rivet-like titanium clamps.

Conventional methods of stabilizing fragments in cranial impression fracture include the use of threads, wires, plates, etc. A new approach to facilitate this surgery is the use of titanium clamps, presented here in five cases, including one with frontal sinus fracture. Surgery was performed on admission day, with the exception of the sinus fracture. Compared with the use of mini- and microplates, the procedure was simple and short. The fixation was very rigid and the esthetic result excellent in all five cases. Skin irritation was minimal, compared with that from miniplates. Computed tomography and MRI compatibility due to artifacts are identical to those with miniplates.

New aspects of prognostic factors in adenocarcinomas of the small bowel.

BACKGROUND/AIMS: Primary small bowel tumors are rare and the prognosis is generally considered to be poor. Histologically chiefly adenocarcinomas are reported. The surgeon is challenged in their treatment, because of the infrequency, unspecific symptoms and delay in diagnosis. Retrospectively we investigated the surgical therapy, combined morbidity, survival rates and prognostic factors in a large series of primary adenocarcinomas of the small bowel at a single surgical center. METHODOLOGY: Between 1985 and 1998, 94 patients with a primary tumors of the small bowel (malignant n = 62 [65.9%], benign n = 32 [34.1%]) were operated on. The subgroup of the adenocarcinomas (n = 22) were considered for this study. RESULTS: The median follow-up is 8.4 years (range: 0.9-14.2 years). Sixteen patients had a follow-up more than 5 years. The main surgical procedure was a small bowel segment resection. Morbidity was 13.6% (only in patients with a duodenal tumors) and the 30-day mortality 5.6%. The estimated 2-year-survival rate was 66%, the 5-year-survival rate 45%. Univariate analysis identified the presence of the residual tumor (R-status) (P = 0.004), tumor stage according to the UICC (P = 0.01), lymph node metastasis (P = 0.007), distant metastasis (P = 0.001), lymphangiosis carcinomatosa (P = 0.001) and vascular invasion (P = 0.0008) as prognostic factors. CONCLUSIONS: A complete macroscopic and microscopic tumor resection including a systemic lymph node dissection has to be the aim of any curative surgical approach in patients with adenocarcinoma of the small bowel.

Prediction of response to preoperative chemotherapy in adenocarcinomas of the esophagogastric junction by metabolic imaging.

PURPOSE: Preoperative chemotherapy in patients with gastroesophageal cancer is hampered by the lack of reliable predictors of tumor response. This study evaluates whether positron emission tomography (PET) using fluorine-18 fluorodeoxyglucose (FDG) may predict response early in the course of therapy. PATIENTS AND METHODS: Forty consecutive patients with locally advanced adenocarcinomas of the esophagogastric junction were studied by FDG-PET at baseline and 14 days after initiation of cisplatin-based polychemotherapy. Clinical response (reduction of tumor length and wall thickness by > 50%) was evaluated after 3 months of therapy using endoscopy and standard imaging techniques. Patients with potentially resectable tumors underwent surgery, and tumor regression was assessed histopathologically. RESULTS: The reduction of tumor FDG uptake (mean +/- 1 SD) after 14 days of therapy was significantly different between responding (-54% +/- 17%) and nonresponding tumors (-15% +/- 21%). Optimal differentiation was achieved by a cutoff value of 35% reduction of initial FDG uptake. Applying this cutoff value as a criterion for a metabolic response predicted clinical response with a sensitivity and specificity of 93% (14 of 15 patients) and 95% (21 of 22), respectively. Histopathologically complete or subtotal tumor regression was achieved in 53% (eight of 15) of the patients with a metabolic response but only in 5% (one of 22) of the patients without a metabolic response. Patients without a metabolic response were also characterized by significantly shorter time to progression/recurrence (P =.01) and shorter overall survival (P =.04). CONCLUSION: PET imaging may differentiate responding and nonresponding tumors early in the course of therapy. By avoiding ineffective and potentially harmful treatment, this may markedly facilitate the use of preoperative therapy, especially in patients with potentially resectable tumors.

Neoadjuvant therapy for patients with locally advanced gastric carcinoma with etoposide, doxorubicin, and cisplatinum. Closing results after 5 years of follow-up.

BACKGROUND: The intent to curatively treat patients with gastric carcinoma is based on complete surgical resection of the primary tumor and its lymphatic drainage. Postoperative adjuvant chemotherapy has failed to show a significant prognostic advantage for these patients. Preoperative chemotherapy, based on promising results in the treatment of patients with disease in primarily unresectable stages, is still being evaluated for those with locally advanced gastric carcinoma. Most published studies still lack adequate staging methods, and long term results of this treatment modality are not known at present. METHODS: In a Phase II study, a series of 42 patients with locally advanced gastric carcinoma (International Union Against Cancer Stages IIIA, IIIB, and IV) initially were staged with endoscopy, with endoscopic ultrasound to establish the clinical tumor classification, with computed tomography scans to rule out tumor infiltration of adjacent organs and to detect distant metastases, and with surgical laparoscopy to exclude occult peritoneal carcinomatosis. Three or four planned cycles of neoadjuvant chemotherapy with etoposide, doxorubicin, and cisplatinum were given prior to total gastrectomy. RESULTS: After a complete follow-up of at least 5 years, there was a median survival of 19.1 months for all patients. Only patients who underwent a complete surgical tumor resection appeared to have a survival benefit, with a median survival of 28.4 months. A superior survival rate was seen in patients who had a major clinical response to chemotherapy, with a median survival of 45 months. CONCLUSIONS: Phase III studies comparing results from patients who undergo neoadjuvant chemotherapy followed by surgery with results from patients who undergo surgery alone should stress the value of adequate pretherapeutic staging and must be accompanied by studies of potential methods for predicting tumor response.

Neoadjuvant therapy of esophageal squamous cell carcinoma: response evaluation by positron emission tomography.

OBJECTIVE: To evaluate the use of positron emission tomography using [(18)F]-fluorodeoxyglucose (FDG-PET) to assess the response to neoadjuvant radiotherapy and chemotherapy in patients with locally advanced esophageal cancer. SUMMARY BACKGROUND DATA: Imaging modalities, including endoscopy, endoscopic ultrasound, computed tomography, and magnetic resonance imaging, currently used to evaluate response to neoadjuvant treatment in esophageal cancer do not reliably differentiate between responders and nonresponders. METHODS: Twenty-seven patients with histopathologically proven squamous cell carcinoma of the esophagus, located at or above the tracheal bifurcation, underwent neoadjuvant therapy consisting of external-beam radiotherapy and 5-fluorouracil as a continuous infusion. FDG-PET was performed before and 3 weeks after the end of radiotherapy and chemotherapy (before surgery). Quantitative measurements of tumor FDG uptake were correlated with histopathologic response and patient survival. RESULTS: After neoadjuvant therapy, 24 patients underwent surgery. Histopathologic evaluation revealed less than 10% viable tumor cells in 13 patients (responders) and more than 10% viable tumor cells in 11 patients (nonresponders). In responders, FDG uptake decreased by 72% +/- 11%; in nonresponders, it decreased by only 42% +/- 22%. At a threshold of 52% decrease of FDG uptake compared with baseline, sensitivity to detect response was 100%, with a corresponding specificity of 55%. The positive and negative predictive values were 72% and 100%. Nonresponders to PET scanning had a significantly worse survival after resection than responders. CONCLUSION: FDG-PET is a valuable tool for the noninvasive assessment of histopathologic tumor response after neoadjuvant radiotherapy and chemotherapy.

[Lumbar lateral recess stenosis. Clinical symptoms, diagnostic modalities and surgical management]. / Die lumbale Rezessusstenose. Klinische Symptome, Diagnostik und operative Therapie.

BACKGROUND: In spite of its importance for lumbar radicular syndroms only a few reports about lumbar lateral recess stenosis exist in literature. Most important clinical symptom is radicular pain, which may be exercise-dependent. Confirmation of diagnosis and differentiation from disc herniation requires imaging like CT, MRI or post-myelo-CT. Surgical treatment options include selective decompression techniques like foraminotomy, medial facettectomy and undercutting as well as hemilaminectomy, laminotomy and wide laminectomy or fusion. METHOD: We treated 35 patients with selective decompression techniques. RESULTS: In the follow-up 5 up to 18 months after surgery 25 patients for themselves described the results as good or excellent. Therefore, individually tailored selective microsurgical decompression is an appropriate and successful treatment strategy for lumbar lateral recess stenosis, if conservative treatment fails.