Evidence-Based Network Modelling to Simulate Nucleus Pulposus Multicellular Activity in Different Nutritional and Pro-Inflammatory Environments.

Initiation of intervertebral disc degeneration is thought to be biologically driven. This reflects a process, where biochemical and mechanical stimuli affect cell activity (CA) that compromise the tissue strength over time. Experimental research enhanced our understanding about the effect of such stimuli on different CA, such as protein synthesis or mRNA expression. However, it is still unclear how cells respond to their native environment that consists of a "cocktail" of different stimuli that might locally vary. This work presents an interdisciplinary approach of experimental and in silico research to approximate Nucleus Pulposus CA within multifactorial biochemical environments. Thereby, the biochemical key stimuli glucose, pH, and the proinflammatory cytokines TNF-α and IL1ß were considered that were experimentally shown to critically affect CA. To this end, a Nucleus Pulposus multicellular system was modelled. It integrated experimental findings from in vitro studies of human or bovine Nucleus Pulposus cells, to relate the individual effects of targeted stimuli to alterations in CA. Unknown stimulus-CA relationships were obtained through own experimental 3D cultures of bovine Nucleus Pulposus cells in alginate beads. Translation of experimental findings into suitable parameters for network modelling approaches was achieved thanks to a new numerical approach to estimate the individual sensitivity of a CA to each stimulus type. Hence, the effect of each stimulus type on a specific CA was assessed and integrated to approximate a multifactorial stimulus environment. Tackled CA were the mRNA expressions of Aggrecan, Collagen types I & II, MMP3, and ADAMTS4. CA was assessed for four different proinflammatory cell states; non-inflamed and inflamed for IL1ß, TNF-α or both IL1ß&TNF-α. Inflamed cell clusters were eventually predicted in a multicellular 3D agent-based model. Experimental results showed that glucose had no significant impact on proinflammatory cytokine or ADAMTS4 mRNA expression, whereas TNF-α caused a significant catabolic shift in most explored CA. In silico results showed that the presented methodology to estimate the sensitivity of a CA to a stimulus type importantly improved qualitative model predictions. However, more stimuli and/or further experimental knowledge need to be integrated, especially regarding predictions about the possible progression of inflammatory environments under adverse nutritional conditions. Tackling the multicellular level is a new and promising approach to estimate manifold responses of intervertebral disc cells. Such a top-down high-level network modelling approach allows to obtain information about relevant stimulus environments for a specific CA and could be shown to be suitable to tackle complex biological systems, including different proinflammatory cell states. The development of this methodology required a close interaction with experimental research. Thereby, specific experimental needs were derived from systematic in silico approaches and obtained results were directly used to enhance model predictions, which reflects a novelty in this research field. Eventually, the presented methodology provides modelling solutions suitable for multiscale approaches to contribute to a better understanding about dynamics over multiple spatial scales. Future work should focus on an amplification of the stimulus environment by integrating more key relevant stimuli, such as mechanical loading parameters, in order to better approximate native physiological environments.

Prospective study of somatostatin receptor scintigraphy and its effect on operative outcome in patients with Zollinger-Ellison syndrome.

OBJECTIVE: To determine the relative abilities of somatostatin receptor scintigraphy (SRS) and conventional imaging studies (computed tomography, magnetic resonance imaging, ultrasound, angiography) to localize gastrinomas before surgery in patients with Zollinger-Ellison syndrome (ZES) subsequently found at surgery, and to determine the effect of SRS on the disease-free rate. SUMMARY BACKGROUND DATA: Recent studies demonstrate that SRS is the most sensitive imaging modality for localizing neuroendocrine tumors such as gastrinomas. Because of conflicting results in small series, it is unclear in ZES whether SRS will alter the disease-free rate, which gastrinomas are not detected, what factors contribute to failure to detect a gastrinoma, or whether the SRS result should be used to determine operability in patients without hepatic metastases, as recently recommended by some investigators. METHODS: Thirty-five consecutive patients with ZES undergoing 37 exploratory laparotomies for possible cure were prospectively studied. All had SRS and conventional imaging studies before surgery. Imaging results were determined by an independent investigator depending on surgical findings. All patients underwent an identical surgical protocol (palpation after an extensive Kocher maneuver, ultrasound during surgery, duodenal transillumination, and 3 cm duodenotomy) and postoperative assessment of disease status (fasting gastrin, secretin test imaging within 2 weeks, at 3 to 6 months, and yearly), as used in pre-SRS studies previously. RESULTS: Gastrinomas were detected in all patients at each surgery. Seventy-four gastrinomas were found: 22 duodenal, 8 pancreatic, 3 primaries in other sites, and 41 lymph node metastases. The relative detection order on a per-patient or per-lesion basis was SRS > angiography, magnetic resonance imaging, computed tomography > ultrasound. On a per-lesion basis, SRS had greater sensitivity than all conventional studies combined. SRS missed one third of all lesions found at surgery. SRS detected 30% of gastrinomas < or =1.1 cm, 64% of those 1.1 to 2 cm, and 96% of those >2 cm and missed primarily small duodenal tumors. Tumor size correlated closely with SRS rate of detection. SRS did not increase the disease-free rate immediately after surgery or at 2 years mean follow-up. CONCLUSIONS: SRS is the most sensitive preoperative imaging study for extrahepatic gastrinomas in patients with ZES and should replace conventional imaging studies as the preoperative study of choice. Negative results of SRS for localizing extrahepatic gastrinomas should not be used to decide operability, because a surgical procedure will detect 33% more gastrinomas than SRS. SRS does not increase the disease-free rate. In the future, more sensitive methods to detect small gastrinomas, especially in the duodenum and in periduodenal lymph nodes, or more extensive surgery will be needed to improve the postoperative disease-free rate in ZES.

Endoscopic ultrasound for staging esophageal cancer, with or without dilation, is clinically important and safe.

BACKGROUND: To fully evaluate patients with esophageal cancer by endoscopic ultrasonography (EUS), the transducer must pass through the entire tumor to the cardia to scan the celiac axis. Dilation may be necessary. Published information suggests that dilation with EUS carries a sizeable risk. METHODS: In order to assess the complication rate associated with dilation prior to EUS in patients with esophageal cancer and the clinical significance of dilation for complete EUS staging, we reviewed the records of all patients who had undergone EUS for esophageal cancer. RESULTS: Sixty-three patients underwent EUS staging of esophageal cancer. Thirty-nine (62%) had lesions through which the EUS scope was passable (Group I). Ten (16%) patients (Group II) had lesions through which an EUS scope (diameter 13 mm) was unable to pass even after dilation. Fourteen patients (22%) had lesions that were dilated to allow passage of the EUS scope (Group III). All patients in Groups II and III had confirmation of EUS staging by CT and/or surgery. In Group II, five patients had tumors defined as T4 (50%) and five as T3 (50%). In Group III, nine (64%) had T4 tumors, four (29%) had T3, and one (7.7%) had T2. No complications were encountered in any group. CONCLUSION: EUS, either alone or after dilation, is a safe procedure and the complete EUS examination with celiac node visualization adds prognostically significant information.

Staging and prognosis using endosonography in patients with inoperable esophageal carcinoma treated with combined intraluminal and external irradiation.

Brachytherapy and external irradiation combined are an alternative to surgery in the treatment of advanced esophageal cancer. Endosonography has proved to be an accurate method of staging the depth of tumor invasion of esophageal cancer. Sixty-three patients with inoperable esophageal cancer underwent endosonography followed by combined brachytherapy and external irradiation. Staging was incomplete in 31 of 63 patients because of tight stenosis or difficulty in imaging celiac lymph nodes. During follow-up of 23 patients, reduction of tumor thickness and lymph node abnormalities was observed in 16. The median survival was 10.4 months. Survival time was correlated with initial number of metastatic lymph nodes found by endosonography. Paradoxically, the survival of patients with more extensive intra-luminal tumor growth was significantly better than survival of those with less tumor growth. In summary, the response to combined brachytherapy and external irradiation could accurately be assessed with endosonography. Lymph node abnormalities and tumor thickness were closely related to survival rate.