Colorectal manifestations of endocrine disease

PURPOSE: The aim of this review is to alert the colon and rectal surgeon to the colorectal manifestations of endocrine disease. METHODS: This report was obtained by a review of the medical literature. Endocrine disease may initially present as a symptom felt to be referable to colorectal disease. Furthermore symptoms of well-established endocrine disorders may have refractory colorectal symptoms. RESULTS: Constipation is the most common gastrointestinal symptom of diabetics; however, in patients with brittle diabetes, diarrhea may be chronic and intermittent. Unexplained diarrhea, despite an exhaustive work-up for an etiology, should alert the clinician to the possibility of a pancreatic endocrine tumor. Thyroid disorders, depending on activity of the gland, may have refractory constipation, diarrhea, or steatorrhea as the only presenting symptoms. Constipation is a common symptom of hypercalcemia, secondary to hyperparathyroidism. Primary hyperparathyroidism has been associated with increased incidence of malignancies, specifically of colonic origin. In patients with acromegaly a threefold to eightfold increased risk of colon carcinoma or adenomatous polyps is seen. Chronic adrenal insufficiency may present initially as diarrhea and malabsorption. The adrenal gland is a frequent site of metastases from colorectal cancer. Pheochromocytomas may be a cause of occult gastrointestinal bleeding or ischemic colitis. CONCLUSION: Unexplained symptoms referable to the colon and rectum should alert the clinician to the possibility of an underlying endocrine disorder.     

Methane steam reforming in a Pd-Ag membrane reformer: An experimental study on reaction pressure influence at middle temperature

In this experimental work, methane steam reforming (MSR) reaction is performed in a dense Pd-Ag membrane reactor and the influence of pressure on methane conversion, CO_x-free hydrogen recovery and CO_x-free hydrogen production is investigated. The reaction is conducted at 450 °C by supplying nitrogen as a sweep gas in co-current flow configuration with respect to the reactants. Three experimental campaigns are realized in the MR packed with Ni-ZrO catalyst, which showed better performances than Ni-Al₂O₃ used in a previous paper dealing with the same MR system. The first one is directed to keep constant the total pressure in both retentate and permeate sides of the membrane reactor. In the second case study, the total retentate pressure is kept constant at 9.0 bar, while the total permeate pressure is varied between 5.0 and 9.0 bar. As the best result of this work, at 450 °C and 4.0 bar of total pressure difference between retentate and permeate sides, around 65% methane conversion and 1.2 l/h of CO_x-free hydrogen are reached, further recovering 80% CO_x-free hydrogen over the total hydrogen produced during the reaction. Moreover, a study on the influence of hydrogen-rich gas mixtures on the hydrogen permeation through the Pd-Ag membrane is also performed and discussed.     

Mechano-Transduction Boosts the Aging Effects in Human Erythrocytes Submitted to Mechanical Stimulation

Erythrocytes’ aging and mechano-transduction are fundamental cellular pathways that determine the red blood cells’ (RBCs) behavior and function. The aging pattern can be influenced, in morphological, biochemical, and metabolic terms by the environmental conditions. In this paper, we studied the effect of a moderate mechanical stimulation applied through external shaking during the RBCs aging and revealed a strong acceleration of the aging pattern induced by such stimulation. Moreover, we evaluated the behavior of the main cellular effectors and resources in the presence of drugs (diamide) or of specific inhibitors of the mechano-transduction (probenecid, carbenoxolone, and glibenclamide). This approach provided the first evidence of a direct cross-correlation between aging and mechano-transduction and permitted an evaluation of the overall metabolic regulation and of the insurgence of specific morphological features, such as micro-vesicles and roughness alterations. Overall, for the first time the present data provided a schematic to understand the integration of distinct complex patterns in a comprehensive view of the cell and of its interactions with the environment. Mechano-transduction produces structural effects that are correlated with the stimulation and the strength of the environmental stimulation is paramount to effectively activate and trigger the biological cascades initiated by the mechano-sensing.     

EmStar: development with high system visibility

Recently, increasing research attention has been directed toward wireless sensor networks: collections of small low-power nodes, physically situated in the environment, that can intelligently deliver high-level sensing results to the user. As the community has moved into more complex design efforts large-scale, long-lived systems that truly require self-organization and adaptivity to the environment - a number of important software design issues have arisen. To make software robust, we must carefully observe its behavior and understand its failure modes. However, many of these failures are not manifested until deployment time. Channel and storage limitations make visibility into a deployed system difficult, hindering our understanding of failure modes. Simulation is difficult to apply; the network's physical situatedness makes it sensitive to subtleties of sensors and wireless communication channels that are difficult to model. In this article we describe EmStar, a PC-based software framework that aims to make development easier by improving system visibility. EmStar's novel execution environments encompass pure simulation, true in-situ deployment, and hybrid modes that combine simulation with real wireless communication and sensors situated in the environment.     

Connectivity of Ad Hoc Networks with Link Asymmetries Induced by Shadowing

The aim of this letter is to determine the minimum node density to achieve a connected large-scale ad hoc network, where every node has the same transmitting and receiving capabilities. Due to the log-normal shadowing, links are unidirectional in general. Contrary to the prevailing opinion, we argue that such asymmetries result into a "reduced" connectivity graph, which, from the point of view of MAC and routing protocols, is to be considered the true or effective connectivity graph. Accordingly, we derive a new formula for the connection probability between two nodes in order to compute global connectivity. Finally, theoretical findings, borrowed from random graphs theory, are compared to numerical simulation results in synthetic wireless network scenarios.     

Functional vasopressin V1 type receptors are present in variant as well as classical forms of small-cell carcinoma

Vasopressin and other neuropeptides are believed to serve as autocrine growth factors for small-cell carcinoma of the lung (SCCL), and these mitogenic influences are reported to involve increases in intracellular Ca2+. Of the classical and variant forms of SCCL, the latter is not only more drug-resistant but also refractory to vasopressin, and other peptides, with respect to changes in intracellular Ca2+. It is currently unclear if this refractiveness of variant SCCL is due to the absence of involved peptide receptors, to the production of abnormal receptors, or to abnormalities in components of induced transduction cascades. In this study, the presence of structurally-normal and functional vasopressin V1a receptors, was examined in a classical SCCL cell line (NCI H345) that is Ca(2+)-responsive to vasopressin, and a variant SCCL cell line (NCI H82) that is unresponsive in this regard to the peptide. Both cell lines were shown to express an mRNA of 1.9 Kb for the vasopressin V1a receptor. RT-PCR, cloning, and DNA sequencing revealed the structure of the mRNA was identical for both cell lines, and, in turn, identical to the mRNA expressed for this receptor by human liver cells. In both cell lines and liver, this mRNA was shown by Western analysis and RIA to generate major protein products of approximately 70,000 and 43,000 daltons. Vasopressin action on NCI H82 cells resulted in a substantial rise in the levels of total inositol phosphates. However, it was reaffirmed that these changes in inositol phosphates were not accompanied by a rise in Ca2+ levels. All of these data indicate that variant SCCL, as well as classical SCCL, expresses structurally-normal and functional vasopressin V1a receptors, but their activation in variant SCCL raises IP3 levels without a corresponding rise in intracellular Ca2+. This difference between the two SCCL sub-types therefore involves either steps in the inositol triphosphate cascade beyond the activation of phospholipase C, or alternatively, components of other transduction events that might be involved with changes in intracellular Ca2+.     

The Alicia/sup 3/ climbing robot: a three-module robot for automatic wall inspection

The system proposed in this article is the Alicia/sup 3/ climbing robot. The aim of this project is to develop a system that can be adopted in a variety of applications, such as maintenance, building, inspection, and safety in the process and construction industries. The system could be adopted in many places where direct access by a human operator is very expensive because of the need for scaffolding or is very dangerous due to the presence of a hostile environment.     

Indirect evaporative cooling and economy cycle in summer air conditioning

The air‐side economy cycle has a large application in warm and dry climates, where the simple increase in the amount of outside air supplied to the conditioned space can substantially reduce the cooling load. Although the dry‐bulb economy cycle is the simplest implementation, requiring only a dry‐bulb temperature comparison to operate the air flow rate regulation, the greatest potential in cost reduction is achieved by the wet‐bulb economizer (WBE). Indirect evaporative cooling (IEC), based on energy recovery from the saturated exhaust airflow, is another technique to be applied in the reduction of a building cooling load. Preconditioning the outdoor airflow by IEC actually extends the applicability of the WBE. In such a way, specific synergies can be exploited when WBE and IEC are combined, even in humid climates. On the other hand, the largest benefits can be accomplished only by redefining the control strategy of the outside air flow rate. In the present paper, the outside air flow rate control strategies are described both for simple WBE and for preconditioned WBE cycles. Different regulation regions are defined on the psychrometric chart together with the relative control strategies. The incidence of these regions is evaluated for 14 different European and American climates. Finally, the seasonal cooling energy requirements are determined for the dehumidification by cooling process, which can be considered as mainly responsible for cooling energy costs in the considered localities. Traditional, preconditioned by heat recovery and IEC on the exhaust airflow, WBE and PWBE air conditioning cycles are compared. Copyright © 2003 John Wiley & Sons, Ltd.     

Hypertransaminemia and methotrexate: not always a toxic effect?

Serial measurement of liver enzymes is useful to detect liver toxicity due to methotrexate in patients with rheumatoid arthritis or other rheumatic diseases. We have reviewed retrospectively 141 adult patients treated with methotrexate from 1988 to 1991. The more common diagnoses included rheumatoid arthritis (120 cases) and psoriatic arthritis (12 cases). In periodic studies carried our every 2-3 months, a transient increase in transaminase values associated with methotrexate in 13 patients (9.2%) was observed. Two patients developed a viral infection during therapy, one due to cytomegalovirus and the other due to the Epstein-Barr virus. Both patients had a favorable outcome once methotrexate was withdrawn.