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Objectives: Ulcerative colitis (UC) is a chronic inflammatory disorder of unknown aetiology. Gut virome dysbiosis is fundamental in UC progression, although its role in the early phases of the disease is far from fully understood. Therefore, we sought to investigate the role of a virome-associated protein encoded by the Orthohepadnavirus genus, the hepatitis B virus X protein (HBx), in UC aetiopathogenesis. Design: HBx positivity of UC patient-derived blood and gut mucosa was assessed by RT-PCR and Sanger sequencing and correlated with clinical characteristics by multivariate analysis. Transcriptomics was performed on HBx-overexpressing endoscopic biopsies from healthy donors. C57BL/6 mice underwent intramucosal injections of liposome-conjugated HBx-encoding plasmids or the control, with or without antibiotic treatment. Multidimensional flow cytometry analysis was performed on colonic samples from HBx-treated and control animals. Transepithelial electrical resistance measurement, proliferation assay, chromatin immunoprecipitation assay with sequencing and RNA-sequencing were performed on in vitro models of the gut barrier. HBx-silencing experiments were performed in vitro and in vivo. Results: HBx was detected in about 45% of patients with UC and found to induce colonic inflammation in mice, while its silencing reverted the colitis phenotype in vivo. HBx acted as a transcriptional regulator in epithelial cells, provoking barrier leakage and altering both innate and adaptive mucosal immunity ex vivo and in vivo. Conclusion: This study described HBx as a contributor to the UC pathogenesis and provides a new perspective on the virome as a target for tailored treatments.

Background and Objectives: Midlife hearing loss (HL) has been considered as a major modifiable risk factor for a later-life progression to dementia. Our aim was to detect a link between precocious sensorineural hearing loss (SNHL) and mild cognitive impairment (MCI) and their association to putative risk factors for a common pathology. Materials and methods: In this study, a retrospective case-control study was carried out. A total of 112 patients were enrolled as following: 81 patients with bilateral SNHL and 31 subjects with normal hearing, whose ages ranged from 50 to 65 years. Both groups performed pure tone audiometry, a tinnitus handicap inventory (THI), Mini-Mental State examination (MMSE), and the Montreal Cognitive Assessment (MoCA), Hospital Anxiety and Depression Scale (HADS-A and HADS-D). Results: The mean age was 58 ± 5.2 in SNHL patients and 53.2 ± 4.8 in the control group. The mean pure tone average in the SNHL group was 40.2 ± 18.7 dB HL on the right side and 41.2 ± 17.2 dB HL on the left side, while in the control group it was 12.5 ± 2.8 dB HL on right side and 12.4 ± 3.1 dB HL on left side. About 64% of patients with SNHL exhibited comorbidities, and the most common condition was hypertension. Altered MoCA test scores were significantly related to the pure tone averages in patients with SNHL compared to the control group (p = 0.0004), while the differences in the HADS-A and HADS-D were not significant. Furthermore, a significant correlation was observed in SNHL patients between an altered MoCA test and hypercholesterolemia (p = 0.043). Conclusions: Hearing impairment and screening tests to detect MCI should be considered in the midlife in order to carry out strategies to prevent the progression to dementia. Hypertension and hypercholesterolemia are two risk factors in the development of endothelial dysfunction, oxidative stress, and vascular inflammation, and may represent the common pathology linking the inner ear and brain damage.

Brain-derived neurotrophic factor (BDNF) has a crucial function in the central nervous system and in sensory structures including olfactory and auditory systems. Many studies have highlighted the protective effects of BDNF in the brain, showing how it can promote neuronal growth and survival and modulate synaptic plasticity. On the other hand, conflicting data about BDNF expression and functions in the cochlear and in olfactory structures have been reported. Several clinical and experimental research studies showed alterations in BDNF levels in neurodegenerative diseases affecting the central and peripheral nervous system, suggesting that BDNF can be a promising biomarker in most neurodegenerative conditions, including Alzheimer's disease, shearing loss, or olfactory impairment. Here, we summarize current research concerning BDNF functions in brain and in sensory domains (olfaction and hearing), focusing on the effects of the BDNF/TrkB signalling pathway activation in both physiological and pathological conditions. Finally, we review significant studies highlighting the possibility to target BDNF as a biomarker in early diagnosis of sensory and cognitive neurodegeneration, opening new opportunities to develop effective therapeutic strategies aimed to counteract neurodegeneration.

Background: Despite increasing use of next-generation sequencing (NGS), data concerning the gain in germline pathogenic variants (PVs) remain scanty, especially with respect to uncanonical ones. We aimed to verify the impact of different cancer predisposition genes (CPGs) on colorectal cancer (CRC) in patients referred for genetic evaluation. Materials and methods: We enrolled for NGS, by Illumina TruSight Cancer panel comprising 94 CPGs, 190 consecutive subjects referred for microsatellite instability (MSI) CRC, polyposis, and/or family history. Results: Overall, 51 (26.8%) subjects carried 64 PVs; PVs coexisted in 4 (7.8%) carriers. PVs in mismatch repair (MMR) genes accounted for one-third of variant burden (31.3%). Four Lynch syndrome patients (20%) harbored additional PVs (HOXB13, CHEK2, BRCA1, NF1 plus BRIP1); such multiple PVs occurred only in subjects with PVs in mismatch syndrome genes (4/20 versus 0/31; P = 0.02). Five of 22 (22.7%) patients with MSI cancers but wild-type MMR genes harbored PVs in unconventional genes (FANCL, FANCA, ATM, PTCH1, BAP1). In 10/63 patients (15.9%) with microsatellite stable CRC, 6 had MUTYH PVs (2 being homozygous) and 4 exhibited uncanonical PVs (BRCA2, BRIP1, MC1R, ATM). In polyposis, we detected PVs in 13 (25.5%) cases: 5 (9.8%) in APC, 6 (11.8%) with biallelic PVs in MUTYH, and 2 (3.9%) in uncanonical genes (FANCM, XPC). In subjects tested for family history only, we detected two carriers (18.2%) with PVs (ATM, MUTYH). Conclusion: Uncanonical variants may account for up to one-third of PVs, underlining the urgent need of consensus on clinical advice for incidental findings in cancer-predisposing genes not related to patient phenotype. Keywords: DNA microsatellite instability; colorectal cancer; colorectal cancer genes; gene testing; inherited cancers.

Objectives: Tinnitus is a common symptom largely impactful on quality of life, especially in the elderly. Our aim was to evaluate the efficacy of self-administered screening tests to correlate the severity of subjective perception of tinnitus with emotional disorders and the overall cognitive status. Methods: Patients aged ≥ 55 years with chronic tinnitus were recruited and submitted to a complete audiological evaluation; Tinnitus Handicap inventory (THI); Hospital Anxiety and Depression Scale (HADS-A and HADS-D) and Mini-Mental State Examination (MMSE). Demographic and audiological features of patients with and without cognitive impairment (MMSE score cut-off of 24/30) were analyzed in order to reveal the relationship among tinnitus, emotional disorders, and cognitive dysfunction. Results: 102 patients were recruited (mean age: 70.4 ± 9.6). THI score was directly related to HADS-A score (r =.63) HADS-D score (r =.66), whereas there was no relationship between tinnitus severity and MMSE (r =.13). CI and n-CI groups did not differ in the characteristics of tinnitus (p >.05), however, hearing threshold (p =.049) and anxious depressive traits measured with HADS-A (p =.044) and HADS-D (p =.016) were significantly higher in the group with cognitive impairment. Furthermore, age ≥ 75 years (p =.002, OR = 13.8), female sex (p =.032; OR = 6.5), severe hearing loss (p =.036; OR = 2.3), and anxiety (p =.029; OR = 9.2) resulted risk factors for CI. Therefore, in CI group MMSE score was inversely related to age (r = −.84). Conclusions: Cognitive impairment and psychiatric discomfort should be considered in tinnitus patients, related to increasing age, female sex, and severe hearing loss. Thus, self-administered questionnaires can be useful in addressing clinical approach.

Colorectal cancer is a major cause of cancer-related death in Western countries and is associated with increased numbers of lymphatic vessels (LV) and tumor-associated macrophages (TAM). The VEGFC/VEGFR3 pathway is regarded as the principal inducer of lymphangiogenesis and it contributes to metastases; however, no data are available regarding its role during primary colorectal cancer development. We found that both VEGFC and VEGFR3 were upregulated in human non-metastatic colorectal cancer, with VEGFR3 expressed on both LVs and TAMs. With the use of three different preclinical models of colorectal cancer, we also discovered that the VEGFC/VEGFR3 axis can shape both lymphatic endothelial cells and TAMs to synergistically inhibit antitumor immunity and promote primary colorectal cancer growth. Therefore, VEGFR3-directed therapy could be envisioned for the treatment of nonmetastatic colorectal cancer.Significance: The prolymphangiogenic factor VEGFC is abundant in colorectal cancer and activates VEGFR3 present on cancer-associated macrophages and lymphatic vessels; activation of VEGFR3 signaling fosters cancer immune escape, resulting in enhanced tumor growth.

Tumor-associated macrophages (TAMs) play a role in tumor development and progression. We hypothesized that abundance of TAMs might modify efficacy of 5-fluorouracil chemotherapy in colorectal cancer. We measured the density of CD68+ TAMs at the invasive front of primary tumor of colorectal carcinoma (PT-TAMs; n = 208), at available matched metastatic lymph node (LN-TAMs; n = 149), and in an independent set of primary colorectal cancers (PT-TAMs, n = 111). The hazard ratios for disease-free survival were computed by Cox proportional-hazards model. In exploratory analysis, the interaction between TAMs and 5-fluorouracil adjuvant therapy was significant (PT-TAMs, p=0.02; LN-TAMs, p D 0.005). High TAMs were independently associated with better disease-free survival only in 5-fluorouracil-treated patients (PT-TAMs, HR 0.23; 95% CI, 0.08-0.65; p=0.005; LN-TAMs, HR 0.13; 95% CI, 0.04-0.43; p D 0.001). The independent predictive value of PT-TAMs was replicated in the external set (HR, 0.14; 95% CI 0.02-1.00; p=0.05). In an in vitro experiment, 5-fluorouracil and macrophages showed a synergistic effect and increased colorectal cancer cell death. High densities of TAMs, particularly in metastatic lymph-nodes, identify stage III colorectal cancer patients benefitting from 5-fluorouracil adjuvant therapy.

Tumor-associated macrophages (TAMs) play a role in tumor development and progression. We hypothesized that abundance of TAMs might modify efficacy of 5-fluorouracil chemotherapy in colorectal cancer. We measured the density of CD68+ TAMs at the invasive front of primary tumor of colorectal carcinoma (PT-TAMs; n = 208), at available matched metastatic lymph node (LN-TAMs; n = 149), and in an independent set of primary colorectal cancers (PT-TAMs, n = 111). The hazard ratios for disease-free survival were computed by Cox proportional-hazards model. In exploratory analysis, the interaction between TAMs and 5-fluorouracil adjuvant therapy was significant (PT-TAMs, p=0.02; LN-TAMs, p D 0.005). High TAMs were independently associated with better disease-free survival only in 5-fluorouracil-treated patients (PT-TAMs, HR 0.23; 95% CI, 0.08-0.65; p=0.005; LN-TAMs, HR 0.13; 95% CI, 0.04-0.43; p D 0.001). The independent predictive value of PT-TAMs was replicated in the external set (HR, 0.14; 95% CI 0.02-1.00; p=0.05). In an in vitro experiment, 5-fluorouracil and macrophages showed a synergistic effect and increased colorectal cancer cell death. High densities of TAMs, particularly in metastatic lymph-nodes, identify stage III colorectal cancer patients benefitting from 5-fluorouracil adjuvant therapy.

Tumor-associated macrophages (TAMs) play a role in tumor development and progression. We hypothesized that abundance of TAMs might modify efficacy of 5-fluorouracil chemotherapy in colorectal cancer. We measured the density of CD68+ TAMs at the invasive front of primary tumor of colorectal carcinoma (PT-TAMs; n = 208), at available matched metastatic lymph node (LN-TAMs; n = 149), and in an independent set of primary colorectal cancers (PT-TAMs, n = 111). The hazard ratios for disease-free survival were computed by Cox proportional-hazards model. In exploratory analysis, the interaction between TAMs and 5-fluorouracil adjuvant therapy was significant (PT-TAMs, p=0.02; LN-TAMs, p D 0.005). High TAMs were independently associated with better disease-free survival only in 5-fluorouracil-treated patients (PT-TAMs, HR 0.23; 95% CI, 0.08-0.65; p=0.005; LN-TAMs, HR 0.13; 95% CI, 0.04-0.43; p D 0.001). The independent predictive value of PT-TAMs was replicated in the external set (HR, 0.14; 95% CI 0.02-1.00; p=0.05). In an in vitro experiment, 5-fluorouracil and macrophages showed a synergistic effect and increased colorectal cancer cell death. High densities of TAMs, particularly in metastatic lymph-nodes, identify stage III colorectal cancer patients benefitting from 5-fluorouracil adjuvant therapy.

Tumor-associated macrophages (TAMs) play a role in tumor development and progression. We hypothesized that abundance of TAMs might modify efficacy of 5-fluorouracil chemotherapy in colorectal cancer. We measured the density of CD68+ TAMs at the invasive front of primary tumor of colorectal carcinoma (PT-TAMs; n = 208), at available matched metastatic lymph node (LN-TAMs; n = 149), and in an independent set of primary colorectal cancers (PT-TAMs, n = 111). The hazard ratios for disease-free survival were computed by Cox proportional-hazards model. In exploratory analysis, the interaction between TAMs and 5-fluorouracil adjuvant therapy was significant (PT-TAMs, p = 0.02; LN-TAMs, p = 0.005). High TAMs were independently associated with better disease-free survival only in 5-fluorouracil-treated patients (PT-TAMs, HR 0.23; 95%CI, 0.08-0.65; p = 0.005; LN-TAMs, HR 0.13; 95%CI, 0.04-0.43; p = 0.001). The independent predictive value of PT-TAMs was replicated in the external set (HR, 0.14; 95%CI 0.02-1.00; p = 0.05). In an in vitro experiment, 5-fluorouracil and macrophages showed a synergistic effect and increased colorectal cancer cell death. High densities of TAMs, particularly in metastatic lymph-nodes, identify stage III colorectal cancer patients benefitting from 5-fluorouracil adjuvant therapy.

Tumor-associated macrophages (TAMs) play a role in tumor development and progression. We hypothesized that abundance of TAMs might modify efficacy of 5-fluorouracil chemotherapy in colorectal cancer. We measured the density of CD68+ TAMs at the invasive front of primary tumor of colorectal carcinoma (PT-TAMs; n = 208), at available matched metastatic lymph node (LN-TAMs; n = 149), and in an independent set of primary colorectal cancers (PT-TAMs, n = 111). The hazard ratios for disease-free survival were computed by Cox proportional-hazards model. In exploratory analysis, the interaction between TAMs and 5-fluorouracil adjuvant therapy was significant (PT-TAMs, p=0.02; LN-TAMs, p D 0.005). High TAMs were independently associated with better disease-free survival only in 5-fluorouracil-treated patients (PT-TAMs, HR 0.23; 95% CI, 0.08-0.65; p=0.005; LN-TAMs, HR 0.13; 95% CI, 0.04-0.43; p D 0.001). The independent predictive value of PT-TAMs was replicated in the external set (HR, 0.14; 95% CI 0.02-1.00; p=0.05). In an in vitro experiment, 5-fluorouracil and macrophages showed a synergistic effect and increased colorectal cancer cell death. High densities of TAMs, particularly in metastatic lymph-nodes, identify stage III colorectal cancer patients benefitting from 5-fluorouracil adjuvant therapy.

Tumor-associated macrophages (TAMs) play a role in tumor development and progression. We hypothesized that abundance of TAMs might modify efficacy of 5-fluorouracil chemotherapy in colorectal cancer. We measured the density of CD68+ TAMs at the invasive front of primary tumor of colorectal carcinoma (PT-TAMs; n = 208), at available matched metastatic lymph node (LN-TAMs; n = 149), and in an independent set of primary colorectal cancers (PT-TAMs, n = 111). The hazard ratios for disease-free survival were computed by Cox proportional-hazards model. In exploratory analysis, the interaction between TAMs and 5-fluorouracil adjuvant therapy was significant (PT-TAMs, p=0.02; LN-TAMs, p D 0.005). High TAMs were independently associated with better disease-free survival only in 5-fluorouracil-treated patients (PT-TAMs, HR 0.23; 95% CI, 0.08-0.65; p=0.005; LN-TAMs, HR 0.13; 95% CI, 0.04-0.43; p D 0.001). The independent predictive value of PT-TAMs was replicated in the external set (HR, 0.14; 95% CI 0.02-1.00; p=0.05). In an in vitro experiment, 5-fluorouracil and macrophages showed a synergistic effect and increased colorectal cancer cell death. High densities of TAMs, particularly in metastatic lymph-nodes, identify stage III colorectal cancer patients benefitting from 5-fluorouracil adjuvant therapy.

Objective Infl ammation plays crucial roles in the pathogenesis of several chronic inflammatory disorders, including Crohn's disease (CD) and UC, the two major forms of IBD. The urokinase plasminogen activator receptor (uPAR) exerts pleiotropic functions over the course of both physiological and pathological processes. uPAR not only has a key role in fibrinolysis but also modulates the development of protective immunity. Additionally, uPAR supports extracellular matrix degradation and regulates cell migration, adhesion and proliferation, thus influencing the development of infl ammatory and immune responses. This study aimed to evaluate the role of uPAR in the pathogenesis of IBD. Design The functional role of uPAR was assessed in established experimental models of colitis. uPAR deficiency effects on cytokine release, polarisation and bacterial phagocytosis were analysed in colonic macrophages. uPAR expression was analysed in surgical specimens collected from normal subjects and patients with IBD. Results In mice, uPAR expression is positively regulated as colitis progresses. uPAR-KO mice displayed severe inflammation compared with wild-type littermates, as indicated by clinical assessment, endoscopy and colon histology. The absence of uPAR led to an increased production of inflammatory cytokines by macrophages that showed an M1 polarisation and impaired phagocytosis. In human IBD, CD68+ macrophages derived from the inflamed mucosa expressed low levels of uPAR. Conclusions These findings point to uPAR as an essential component of intestinal macrophage functions and unravel a new potential target to control mucosal inflammation in IBD.

The complete control of steatorrhea in postsurgical exocrine pancreatic insufficiency is difficult. The aim of this study was to evaluate the effect of the association of ranitidine with pancrelipase on fecal fat excretion in patients who had undergone a pancreatoduodenectomy with suppression of the exocrine pancreatic secretion by Neoprene injection. Ten patients were studied 1 year after surgery. Steatorrhea was measured as an integrated test of 3-day stools, while patients were kept on a diet of 100 g lipid/day, with their usual enzyme supplementation therapy (16,050 USP units of lipase/meal). A basal 24-h gastroenteric pH profile was also obtained. In the following month, patients had ranitidine (150 mg twice a day) in addition to pancrelipase. Then steatorrhea and gastroenteric pH were reassessed. Mean fecal fat was 26.9 (SD 13.7) g/day without ranitidine and 30.5 (SD 13.9) g/day during combined treatment. Body weight and nutritional parameters did not show any significant variation after ranitidine administration. Even in the absence of ranitidine, postprandial gastroenteric pH values were always >4; the H2-receptor antagonist only reduced fasting gastric acidity. In conclusion, the gastroenteric pH and fecal fat determinations showed that ranitidine is not useful in patients with total postsurgical exocrine pancreatic insufficiency.

Cold polypectomy techniques (without electrocautery) by means of biopsy forceps or snare are widely adopted for the removal of subcentimetric polyps. However, few data are available on the safety of this approach. The aim of this study was to assess the safety of cold polypectomy for subcentimetric polyps, as well as the rate of advanced neoplasia in these lesions.

To assess the efficacy and safety of a balanced approach using midazolam in combination with propofol, administered by non-anesthesiologists, in a large series of diagnostic colonoscopies.

This paper gives practical guidelines for diagnosis and treatment of chronic pancreatitis. Statements have been elaborated by working teams of experts, by searching for and analysing the literature, and submitted to a consensus process by using a Delphi modified procedure. The statements report recommendations on clinical and nutritional approach, assessment of pancreatic function, treatment of exocrine pancreatic failure and of secondary diabetes, treatment of pain and prevention of painful relapses. Moreover, the role of endoscopy in approaching pancreatic pain, pancreatic stones, duct narrowing and dilation, and complications was considered. Recommendations for most appropriate use of various imaging techniques and of ultrasound endoscopy are reported. Finally, a group of recommendations are addressed to the surgical treatment, with definition of right indications, timing, most appropriate procedures and techniques in different clinical conditions and targets, and clinical and functional outcomes following surgery. (C) 2010 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Benign esophageal strictures refractory to standard dilation therapy present a challenging problem. Temporary plastic and metal stents have been proposed with inconclusive results.

Although endoscopic submucosal dissection (ESD) is becoming accepted as an established treatment for superficial esophageal squamous cell neoplasia, the majority of data on this endoscopic modality has been provided by Japanese series.

Thesis (S.M. in Ocean Systems Management)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006., Includes bibliographical references (p. 190-193)., Seakeeping analysis is a fundamental part of the design process of a ship. Due to its complexity, seakeeping analysis is usually completed in a late stage of the design process. Although this approach can be successfully used for monohull vessels, it is not optimal in designing more innovative hull forms, due to the high degree of uncertainty of the seakeeping performances of these vessels. The recent interest in multihull vessels poses a problem to the naval architecture world as little is known about such hull forms and a limited number of design tools is available to analyze them. These concerns led to the development of the I-Marine Seakeeping Analysis Toolbox that aims to help students and naval architects alike understand the importance of seakeeping analysis and the seakeeping capabilities of multihull vessels. The Toolbox includes five different seakeeping programs suitable for the analysis of multihull vessels and is accessible through a web interface. The integrated nature of I-Marine strongly facilitates the usage of the programs, making it a great educational tool to learn seakeeping analysis without any previous programming knowledge., (cont.) This thesis shows that a tool such as I-Marine could be effectively used in calculating the seakeeping capabilities of multihulls and successfully integrated in the preliminary design of a vessel, leading to numerous advantages such as a higher efficiency in the design process, a reduction in the risk of designing multihulls, and an expansion of the design envelope., by Cosimo Malesci., S.M.in Ocean Systems Management

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005., Includes bibliographical references (p. 79-83)., There have been a number of recent proposals for link and network-layer protocols in the sensor networking literature, each of which claims to be superior to other approaches. However, a proposal for a networking protocol at a given layer in the stack is typically evaluated in the context of a single set of carefully selected protocols at other layers, as well as a particular network topology and application workload. Because of the limited data available about interactions between different protocols at various layers of the stack, it is difficult for developers of sensor network applications to select from amongst the range of alternative sensor networking protocols. This thesis attempts to remedy this situation by evaluating the interaction between several protocols at the MAC and network layers and measuring their performance in terms of end-to-end throughput and loss on a large, real-world TinyOS and Mica2 mote-based tested. We report on different combinations of protocols using different application workloads and power-management schemes. This thesis analyzes the effects of various services provided by the different protocols, such as link-level retransmission, neighborhood management, and link-quality estimation. Our analysis suggests some common sources of poor performance that developers may experience during real-life deployments; based on this experience, we propose a set of design principles and lessons for the designers of future interfaces and services in TinyOS., by Umberto Malesci., M.Eng.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005., Includes bibliographical references (p. 79-83)., There have been a number of recent proposals for link and network-layer protocols in the sensor networking literature, each of which claims to be superior to other approaches. However, a proposal for a networking protocol at a given layer in the stack is typically evaluated in the context of a single set of carefully selected protocols at other layers, as well as a particular network topology and application workload. Because of the limited data available about interactions between different protocols at various layers of the stack, it is difficult for developers of sensor network applications to select from amongst the range of alternative sensor networking protocols. This thesis attempts to remedy this situation by evaluating the interaction between several protocols at the MAC and network layers and measuring their performance in terms of end-to-end throughput and loss on a large, real-world TinyOS and Mica2 mote-based tested. We report on different combinations of protocols using different application workloads and power-management schemes. This thesis analyzes the effects of various services provided by the different protocols, such as link-level retransmission, neighborhood management, and link-quality estimation. Our analysis suggests some common sources of poor performance that developers may experience during real-life deployments; based on this experience, we propose a set of design principles and lessons for the designers of future interfaces and services in TinyOS., by Umberto Malesci., M.Eng.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005., Includes bibliographical references (p. 79-83)., There have been a number of recent proposals for link and network-layer protocols in the sensor networking literature, each of which claims to be superior to other approaches. However, a proposal for a networking protocol at a given layer in the stack is typically evaluated in the context of a single set of carefully selected protocols at other layers, as well as a particular network topology and application workload. Because of the limited data available about interactions between different protocols at various layers of the stack, it is difficult for developers of sensor network applications to select from amongst the range of alternative sensor networking protocols. This thesis attempts to remedy this situation by evaluating the interaction between several protocols at the MAC and network layers and measuring their performance in terms of end-to-end throughput and loss on a large, real-world TinyOS and Mica2 mote-based tested. We report on different combinations of protocols using different application workloads and power-management schemes. This thesis analyzes the effects of various services provided by the different protocols, such as link-level retransmission, neighborhood management, and link-quality estimation. Our analysis suggests some common sources of poor performance that developers may experience during real-life deployments; based on this experience, we propose a set of design principles and lessons for the designers of future interfaces and services in TinyOS., by Umberto Malesci., M.Eng.

The occurrence of maldigestion and malnutrition was studied in 14 patients who had undergone pancreaticoduodenectomy and occlusion of the Wirsung duct with Neoprene®. Before discharge patients were put on a 70 g/day dietary fat intake. Mean faecal fat excretion was 32·9 g/day without enzyme replacement and fell to 14·2 g/day with pancrelipase supplementation. At discharge all patients were underweight (88 per cent of the usual mean body‐weight) and nine patients showed alteration in laboratory nutritional parameters. At the time of discharge a low‐fat diet (50 g/day) was prescribed. Six months after surgery, mean faecal fat excretion decreased further to 8·3 g/day (P < 0·01) and all patients but one gained weight, reaching 93 per cent of the usual mean body‐weight with normalized nutritional parameters. Our data show that the combination of enzyme replacement therapy and low‐fat diet allows good correction of steatorrhoea and a significant improvement in nutritional status.