Gender and line size factors modulate the deviations of the subjective visual vertical induced by head tilt

<p>Abstract</p> <p>Background</p> <p>The subjective visual vertical (SVV, the visual estimation of gravitational direction) is commonly considered as an indicator of the sense of orientation. The present study examined the impact of two methodological factors (the angle size of the stimulus and the participant's gender) on deviations of the SVV caused by head tilt. Forty healthy participants (20 men and 20 women) were asked to make visual vertical adjustments of a light bar with their head held vertically or roll-tilted by 30° to the left or to the right. Line angle sizes of 0.95° and 18.92° were presented.</p> <p>Results</p> <p>The SVV tended to move in the direction of head tilt in women but away from the direction of head tilt in men. Moreover, the head-tilt effect was also modulated by the stimulus' angle size. The large angle size led to deviations in the direction of head-tilt, whereas the small angle size had the opposite effect.</p> <p>Conclusions</p> <p>Our results showed that gender and line angle size have an impact on the evaluation of the SVV. These findings must be taken into account in the growing body of research that uses the SVV paradigm in disease settings. Moreover, this methodological issue may explain (at least in part) the discrepancies found in the literature on the head-tilt effect.</p

Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank

9 páginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved: the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and Conselleria de Pesca de la Xunta de GaliciaPeer reviewe

Atrophy and neoplastic transformation of the ileal pouch mucosa in patients with ulcerative colitis and primary sclerosing cholangitis - A case control study

INTRODUCTION: Patients with ulcerative colitis and primary sclerosing cholangitis have an increased risk of developing carcinoma both in the bile ducts and in the colon. PURPOSE: To investigate whether this patient group also has an increased risk of developing atrophy and neoplasia in the deal pouch mucosa after construction of a pelvic pouch with an ileoanal anastomosis or a continent Kock ileostomy. METHODS: Flexible video endoscopic examinations of the ileal pouch were performed in 16 patients with ulcerative colitis and primary sclerosing cholangitis and in 16 matched patients with ulcerative colitis without sclerosing cholangitis. Biopsies were sampled from different locations in the pouch for histologic assessment of mucosal atrophy and dysplasia and for flow cytometric DNA analysis assessing chromosomal aberrations. RESULTS: The patients with sclerosing cholangitis developed moderate or severe atrophy in the pouch significantly more often (P 8 years). CONCLUSION: Patients with ulcerative colitis and primary sclerosing cholangitis with an ileal reservoir are more prone to developing mucosal atrophy in the pouch and seem to have a higher risk of neoplastic transformation in the pouch mucosa than patients with ulcerative colitis without sclerosing cholangitis

Chronic colitis is associated with a reduction of mucosal alkaline sphingomyelinase activity

Background and Aims: The hydrolysis of sphingomyelin (SM) generates key molecules regulating cell growth. Animal cancer studies support an inhibitory role for this pathway in the malignant transformation of the colonic mucosa. The activity of a specific intestinal alkaline sphingomyelinase (SMase), which hydrolyzes SM, is reduced in colorectal tumors. In this study we measured alkaline SMase activity in patients with longstanding colitis and assessed if a reduction can be used as a marker in surveillance of high risk patients. Methods: Alkaline SMase activity was measured in 139 colonic biopsies from 34 patients with longstanding, extensive colitis and from I I controls. Fifteen patients had earlier diagnosis of dysplasia or DNA aneuploidy. Alkaline SMase activity was related to histologic dysplasia and DNA aneuploidy assessed by flow cytometry, patient age, and duration of disease. Results: Alkaline SMase activity was significantly lower in the patient group with and without dysplasia compared with controls (p = 0.006). In biopsies, an association was not found between alkaline SMase activity, dysplasia, or DNA ploidy. However, alkaline SMase activity decreased with age both in patients and controls (p = 0.008). Conclusions: Reduction of alkaline SMase activity seen in colorectal cancer and adenomas is also present in patients with chronic colitis. It is not complementary to dysplasia or DNA-aneuploidy in the identification of high risk patients. The age-associated decrease of alkaline SMase activity seems to be a general phenomenon indicating premature senescence of the mucosa in longstanding colitis