Neuroimmunomodulation in the Gut: Focus on Inflammatory Bowel Disease.

Intestinal immunity is finely regulated by several concomitant and overlapping mechanisms, in order to efficiently sense external stimuli and mount an adequate response of either tolerance or defense. In this context, a complex interplay between immune and nonimmune cells is responsible for the maintenance of normal homeostasis. However, in certain conditions, the disruption of such an intricate network may result in intestinal inflammation, including inflammatory bowel disease (IBD). IBD is believed to result from a combination of genetic and environmental factors acting in concert with an inappropriate immune response, which in turn interacts with nonimmune cells, including nervous system components. Currently, evidence shows that the interaction between the immune and the nervous system is bidirectional and plays a critical role in the regulation of intestinal inflammation. Recently, the maintenance of intestinal homeostasis has been shown to be under the reciprocal control of the microbiota by immune mechanisms, whereas intestinal microorganisms can modulate mucosal immunity. Therefore, in addition to presenting the mechanisms underlying the interaction between immune and nervous systems in the gut, here we discuss the role of the microbiota also in the regulation of neuroimmune crosstalk involved in intestinal homeostasis and inflammation, with potential implications to IBD pathogenesis.

Analysis of mutations in TP53, APC, K-ras, and DCC genes in the non-dysplastic mucosa of patients with inflammatory bowel disease.

BACKGROUND AND AIMS: Patients with ulcerative colitis (UC) and Crohn's disease (CD) have a high risk for colorectal cancer (CRC). To understand the molecular basis of colitis-associated CRC, we analyzed alterations in TP53, APC, K-ras, and DCC genes in the non-dysplastic UC and CD colon. MATERIALS AND METHODS: Endoscopic biopsies were collected from six predefined colon sites of 35 UC and 12 CD patients for DNA extraction and genetic analysis. RESULTS: A mutation was found in codon 1141 of the APC gene of two CD patients, being somatic in one and germinative in the other. The mutation seen in both patients was a base exchange of thymine for cytosine, resulting in an exchange of leucine for serine. We did not detect any mutations in the other samples analyzed. CONCLUSIONS: Mutations in APC gene may occur in the non-dysplastic CD mucosa of patients with disease for more than 10 years. The follow-up of these patients will show the likelihood of mutant APC progressing to CRC in CD. Further analysis will be required for evaluating the impact of these findings in the context of cancer surveillance in inflammatory bowel disease.

Feasibility of a semiconductor dosimeter to monitor skin dose in interventional radiology.

The design and preliminary test results of a semiconductor silicon dosimeter are presented in this article. Use of this dosimeter is foreseen for real-time skin dose control in interventional radiology. The strong energy dependence of this kind of radiation detector is well overcome by filtering the silicon diode. Here, the optimal filter features have been calculated by numerical Monte Carlo simulations. A prototype has been built and tested in a radiological facility. The first experimental results show a good match between the filtered semiconductor diode response and an ionization chamber response, within 2% fluctuation in a 2.2 to 4.1 mm Al half-value layer (HVL) energy range. Moreover, the semiconductor sensor response is linear from 0.02 Gy/min to at least 6.5 Gy/min, covering the whole dose rate range found in interventional radiology. The results show that a semiconductor dosimeter could be used to monitor skin dose during the majority of procedures using x-rays below 150 keV. The use of this device may assist in avoiding radiation-induced skin injuries and lower radiation levels during interventional procedures.

Interventional radiology with laser in bone and joint.

Laser energy is able to ablate, coagulate, and vaporize tissues. Its transmissibility in thin optical fibers makes it an ideal tool for use in percutaneous procedures. This article describes two applications in interventional musculoskeletal radiology. In percutaneous laser disc decompression the laser source is used to vaporize a small portion of the nucleus pulposus. In interstitial laser photocoagulation of osteoid osteoma the laser energy is used to coagulate and destroy the tumor by direct heating.

Evaluation of the use of six diagnostic X-ray spectra computer codes.

A knowledge of photon energy spectra emitted from X-ray tubes in radiology is crucial for many research domains in the medical field. Since spectrometry is difficult because of high photon fluence rates, a convenient solution is to use computational models. This paper describes the use of six computer codes based on semiempirical or empirical models. The use of the codes was assessed, notably by comparing theoretical half value layers and air kerma with measurements on five different X-ray tubes used in a research hospital. It was found that three out of the six computer codes give relative spectra very close to those produced by X-ray units equipped with constant potential generators: the mean difference between measured and modelled half value layer was less than 3% with a standard deviation of 3.6% whatever the tube and the applied voltage. Absolute output is less accurate: for four computer codes, the mean difference between the measured and modelled air kerma was between 18% and 36%, with a standard deviation of 9% whatever the tube (except for the single phase generator) and the applied voltage. One of the codes gives a good output and beam quality for X-ray units equipped with 100% ripple voltage generators. The use of computational codes as described in this paper provides a means of modelling relative diagnostic X-ray spectra, the usefulness of the tube output data depending on the accuracy required by the end user.

Use of butyrate or glutamine in enema solution reduces inflammation and fibrosis in experimental diversion colitis.

AIM: To investigate whether butyrate or glutamine enemas could diminish inflammation in experimental diversion colitis. METHODS: Wistar specific pathogen-free rats were submitted to a Hartmann's end colostomy and treated with enemas containing glutamine, butyrate, or saline. Enemas were administered twice a week in the excluded segment of the colon from 4 to 12 wk after the surgical procedure. Follow-up colonoscopy was performed every 4 wk for 12 wk. The effect of treatment was evaluated using video-endoscopic and histologic scores and measuring interleukin-1ß, tumor necrosis factor-alpha, and transforming growth factor beta production in organ cultures by enzyme linked immunosorbent assay. RESULTS: Colonoscopies of the diverted segment showed mucosa with hyperemia, increased number of vessels, bleeding and mucus discharge. Treatment with either glutamine or butyrate induced significant reductions in both colonoscopic (P < 0.02) and histological scores (P < 0.01) and restored the densities of collagen fibers in tissue (P = 0.015; P = 0.001), the number of goblet cells (P = 0.021; P = 0.029), and the rate of apoptosis within the epithelium (P = 0.043; P = 0.011) to normal values. The high levels of cytokines in colon explants from rats with diversion colitis significantly decreased to normal values after treatment with butyrate or glutamine. CONCLUSION: The improvement of experimental diversion colitis following glutamine or butyrate enemas highlights the importance of specific luminal nutrients in the homeostasis of the colonic mucosa and supports their utilization for the treatment of human diversion colitis.

Endoscopia na hemorragia digestiva alta: estudo retrospectivo em uma Enfermaria de Clínica Médica / Endoscopy in upper gastrointestinal bleeding: retrospectivy study in Ward of Internal Medicine

A hemorragia digestiva alta (HDA) é uma complicação freqüente de doenças do trato gastrointestinal superior. A endoscopia tornou possível a identificação da fonte de sangramento na maioria dos casos, além de fornecer dados prognósticos e da possibilidade de ser usada como instrumento terapêutico. Foi realizada uma análise retrospectiva dos registros de todos os pacientes internados na 5ª Enfermaria de Clínica Médica com HDA, entre 1995 e 1998. Uma planilha de dados foi montada de acordo com protocolo definido, para o armazenamento das informações e para a realização de testes estatísticos. Hematêmese e(ou) melena foram registradas na maioria dos casos, e a presença de hematêmese aumentou a probabilidade de identificação da fonte do sangramento. A fonte de sangramento foi identificada na maioria dos casos e a precisão diagnóstica foi inversamente proporcional ao intervalo de tempo entre o episódio hemorrágico e a realização do exame. Úlcera péptica foi a causa mais comum de HDA. O índice de sangramento por varizes esofágicas foi mais elevado do que o encontrado na maioria dos estudos norte-americanos e europeus, provavelmente devido à alta prevalência de hepatopatia. Nosso estudo confirmou que a endoscopia terapêutica pode ser utilizada como método eficaz em pacientes selecionados. A taxa geral de ressangramento e a taxa de mortalidade foram inferiores ás de outros estudos epidemiológicos. A elevada prevalência de patologias subjacentes, especialmente da hipertensão portal, não representou risco significativamente aumentado para ressangramento nem para o êxito letal