Towards targeted colorectal cancer biopsy based on tissue morphology assessment by compression optical coherence elastography.

Identifying the precise topography of cancer for targeted biopsy in colonoscopic examination is a challenge in current diagnostic practice. For the first time we demonstrate the use of compression optical coherence elastography (C-OCE) technology as a new functional OCT modality for differentiating between cancerous and non-cancerous tissues in colon and detecting their morphological features on the basis of measurement of tissue elastic properties. The method uses pre-determined stiffness values (Young's modulus) to distinguish between different morphological structures of normal (mucosa and submucosa), benign tumor (adenoma) and malignant tumor tissue (including cancer cells, gland-like structures, cribriform gland-like structures, stromal fibers, extracellular mucin). After analyzing in excess of fifty tissue samples, a threshold stiffness value of 520 kPa was suggested above which areas of colorectal cancer were detected invariably. A high Pearson correlation (r =0.98; p <0.05), and a negligible bias (0.22) by good agreement of the segmentation results of C-OCE and histological (reference standard) images was demonstrated, indicating the efficiency of C-OCE to identify the precise localization of colorectal cancer and the possibility to perform targeted biopsy. Furthermore, we demonstrated the ability of C-OCE to differentiate morphological subtypes of colorectal cancer - low-grade and high-grade colorectal adenocarcinomas, mucinous adenocarcinoma, and cribriform patterns. The obtained ex vivo results highlight prospects of C-OCE for high-level colon malignancy detection. The future endoscopic use of C-OCE will allow targeted biopsy sampling and simultaneous rapid analysis of the heterogeneous morphology of colon tumors.

Measuring Intratumoral Heterogeneity of Immune Repertoires.

There is considerable clinical and fundamental value in measuring the clonal heterogeneity of T and B cell expansions in tumors and tumor-associated lymphoid structures-along with the associated heterogeneity of the tumor neoantigen landscape-but such analyses remain challenging to perform. Here, we propose a straightforward approach to analyze the heterogeneity of immune repertoires between different tissue sections in a quantitative and controlled way, based on a beta-binomial noise model trained on control replicates obtained at the level of single-cell suspensions. This approach allows to identify local clonal expansions with high accuracy. We reveal in situ proliferation of clonal T cells in a mouse model of melanoma, and analyze heterogeneity of immunoglobulin repertoires between sections of a metastatically-infiltrated lymph node in human melanoma and primary human colon tumor. On the latter example, we demonstrate the importance of training the noise model on datasets with depth and content that is comparable to the samples being studied. Altogether, we describe here the crucial basic instrumentarium needed to facilitate proper experimental setup planning in the rapidly evolving field of intratumoral immune repertoires, from the wet lab to bioinformatics analysis.

Interrogation of tumor metabolism in tissue samples ex vivo using fluorescence lifetime imaging of NAD(P)H.

Exploring metabolism in human tumors at the cellular level remains a challenge. The reduced form of metabolic cofactor NAD(P)H is one of the major intrinsic fluorescent components in tissues and a valuable indicator of cellular metabolic activity. Fluorescence lifetime imaging (FLIM) enables resolution of both the free and protein-bound fractions of this cofactor, and thus, high sensitivity detection of relative changes in the NAD(P)H-dependent metabolic pathways in real time. However, the clinical use of this technique is still very limited. The applications of metabolic FLIM could be usefully expanded by probing cellular metabolism in tissues ex vivo. For this, however, the development of appropriate tissue preservation protocols is required in order to maintain the optical metabolic characteristics in the ex vivo sample in a state similar to those of the tumor in vivo. Using mouse tumor models of different histological types-colorectal cancer, lung carcinoma and melanoma-we tested eight different methods of tissue handling by comparing NAD(P)H fluorescence decay parameters ex vivo and in vivo as measured with two-photon excited FLIM microscopy. It was found that the samples placed in 10% BSA on ice immediately after excision maintained the same fluorescence lifetimes and free/bound ratios as measured in vivo for at least 3 hours. This protocol was subsequently used for metabolic assessments in fresh postoperative samples from colorectal cancer patients. A high degree of inter- and intra-tumor heterogeneity with a trend to a more oxidative metabolism was detected in T3 colorectal tumors in comparison with normal tumor-distant colon samples. These results suggest that the methodology developed on the basis of FLIM of NAD(P)H in tissues ex vivo show promise for interrogating the metabolic state of patients' tumors.

Advanced enteral therapy in acute pancreatitis: is there a room for immunonutrition? A meta-analysis.

BACKGROUND: It is believed that certain nutrients such as glutamine, arginine and omega-3 fatty acids may play a significant role in metabolic, inflammatory, and immune processes in acute pancreatitis. The present systematic review aimed to define whether the addition of these substances to enteral nutrition provides any clinical benefit over standard enteral formulas in patients with acute pancreatitis. METHODS: A computerized search on electronic databases (Cochrane Central Register of Controlled Trials, EMBASE and MEDLINE) and manual search of the abstracts of major gastroenterological meetings (UEGW, DDW) were undertaken. The studied outcomes were total infectious complication, in-hospital mortality and length of hospital stay. The data were meta-analyzed using a random-effects model. RESULTS: A total of three randomized controlled trials satisfied the inclusion criteria. When compared with standard enteral nutrition, immunonutrition was not associated with the significantly reduced risk of total infectious complications (risk ratio 0.82; 95% confidence interval 0.44-1.53; P=0.53) and death (risk ratio 0.64; 95% confidence interval 0.20-2.07; P=0.46). Mean difference in length of hospital stay between two groups was not significant (P=0.80). CONCLUSIONS: There is no evidence that enteral nutrition supplemented with glutamine, arginine and/or omega-3 fatty acids, in comparison with standard enteral nutrition, has any beneficial effect on infectious complications, mortality or length of hospital stay in acute pancreatitis. The pursuit of new compositions of enteral formulations in this category of patients may be advocated.

Influence of enteral versus parenteral nutrition on blood glucose control in acute pancreatitis: a systematic review.

BACKGROUND & AIMS: There is increasing evidence that tight glucose control may reduce infectious complications and mortality in surgical critically ill patients. However, data regarding the influence of artificial nutrition on glycemic homeostasis are limited. Our aim was to review all randomized controlled trials on enteral versus parenteral nutrition in acute pancreatitis to determine whether the route of feeding can affect the glucose control in the setting of this disease. METHODS: Relevant literature cited in three electronic databases (Cochrane Central Register of Controlled Trials, EMBASE and Medline) were systematically reviewed. A meta-analysis was carried out using a random-effects model. RESULTS: Thirteen randomized controlled trials on enteral versus parenteral nutrition in acute pancreatitis were identified. Seven studies were excluded from analysis, leaving 6 trials in which a total of 264 non-diabetic patients with acute pancreatitis were treated. Intake of nutrients did not differ among enterally and parenterally fed patients in 5 of 6 randomized controlled trials. Enteral nutrition reduced the risk of hyperglycemia (relative risk 0.53; 95% confidence interval 0.29-0.98; p = 0.04) and insulin requirement (relative risk 0.41; 95% confidence interval 0.24-0.70; p = 0.001). CONCLUSIONS: Enteral nutrition, when compared with parenteral nutrition, is associated with better blood glucose control in patients with acute pancreatitis.