Beaconing Signalization Substantially Reduces Blind Pedestrians' Veer on Snow-Covered Pavement.

Veering outside of crosswalks is a common problem experienced by individuals who are blind. One technology found to be effective for reducing this veer when other guidance cues are absent is audible beaconing. However, veering in general and veering from crosswalks in particular have been studied primarily on smooth, flat walking surfaces such as clear pavement. This experiment compared veering on clear pavement with veering on snow-covered pavement, with and without audible beaconing. Eleven blind participants traveling with long canes attempted to walk a straight path for 72 ft (21.9 m), a typical length of a six-lane crosswalk. Beaconing substantially reduced veering at 36 ft (11.0 m) and 72 ft from the starting point and enabled participants to remain within a simulated crosswalk. Walking on snow was not found to affect veering but did increase the number of steps taken. The findings suggest that in snowy and clear conditions alike, audible beaconing is an effective wayfinding tool for intersections equipped with accessible pedestrian signals.

Blind and sighted pedestrians' road-crossing judgments at a single-lane roundabout.

OBJECTIVE: The aim of this study was to evaluate the relative risk and efficiency of road crossing experienced by blind and sighted pedestrians at a single-lane roundabout with two levels of traffic volume and at two distances from the roundabout. BACKGROUND: With the rapid spread of modern roundabouts across the United States,their accessibility to blind pedestrians has become an important concern. To date, accessibility research relevant to blind pedestrians has focused on multilane roundabouts, and single-lane roundabouts have been virtually ignored. METHOD: Blind and sighted participants made judgments about when they would cross a single-lane roundabout with high and low traffic volumes, at exit and entry lanes, and at the actual crosswalks and at locations farther from the roundabout. RESULTS: Relative to sighted participants, blind participants' judgments about when to cross were more frequently risky, especially when traffic volume was high. Blind participants also were slower to make crossing judgments and accepted fewer crossing opportunities. Both groups made somewhat safer and more efficient judgments at locations farther from the roundabout. CONCLUSION: Some single-lane roundabouts may pose greater risk to blind pedestrians than to sighted pedestrians, especially when traffic volume is high. Crosswalk location merits further investigation as a design issue. APPLICATION: These findings are relevant to transportation planners and engineers who are responsible for the accessibility of public rights-of-way.

Elevated expression of iNOS mRNA and protein in coeliac disease.

BACKGROUND: The role of nitric oxide synthase (NOS) in the pathophysiology of coeliac disease (CD) was investigated. METHODS: We examined mRNA (reverse transcription multiplex polymerase chain reaction) and protein expression (Western blotting) of i,e and nNOS in enterocytes isolated from the duodenum of patients with untreated CD (n=22) and iron deficiency anaemia (IDA, n=22). Expression of IL1beta and TNFalpha, two pivotal "NOS-controlling" cytokines, was also studied. RESULTS: Enterocytes from both patient groups were negative for eNOS and TNF(alpha) message but positive for n and iNOS. nNOS gene expression was not statistically different between groups (158.38+/-29.11% vs. 114.95+/-24.17%, IDA vs. CD, p=0.07, Mann-Whitney U). iNOS expression was higher in patients with CD when compared to patients with IDA (96.95+/-17.82% vs. 48.76+/-8.07%, p<0.006). Low levels of IL1beta mRNA (15.66+/-3.70%) were detected in nine samples-all of these samples were isolated from patients with CD representing a positive result in 40% of coeliac patients. In support of these observations, patients with CD expressed more iNOS protein than those with IDA (159.7+/-14.9% vs. 69.8+/-20%, p<0.05). CONCLUSION: These results suggest that iNOS could be an important mediator in coeliac disease. Expression of this regulatory protein may be under the control of IL1beta.

Fasting plasma nitric oxide products in coeliac disease.

OBJECTIVES: In coeliac disease, inducible nitric oxide synthase activity in the duodenal mucosa is greatly increased, resulting in increased production of nitric oxide. We investigated whether this resulted in increased plasma concentrations of its stable end products (nitrate/nitrite: NOx). METHODS: Fasting plasma NOx was determined in 66 patients attending for upper gastrointestinal endoscopy. Of these, 21 had coeliac disease (nine were on a gluten-free diet). The remainder had a variety of other gastrointestinal disorders. NOx was determined using the Griess reaction. Distal duodenal biopsies for coeliac patients were graded according to the Marsh score. RESULTS: Patients with untreated coeliac disease had a higher fasting NOx concentration (mean 117.5 microM) than either those with coeliac disease taking a gluten-free diet (mean 71.2 microM) or those with other diseases (mean 33.5 microM; one-way analysis of variance, P < 0.001). Coeliac patients with higher fasting NOx concentrations had more marked histological changes (P < 0.05). CONCLUSION: Fasting plasma NOx is significantly elevated in untreated coeliac disease and correlates with histological grade. The potential clinical utility of serial NOx measurements to monitor improvement on a gluten-free diet requires further study.

Increased activity and expression of iNOS in human duodenal enterocytes from patients with celiac disease.

The activity of nitric oxide synthase (NOS) was assayed in enterocytes isolated from human duodenal biopsies to determine its role in celiac disease. Patients were categorized into groups with irritable bowel syndrome, iron-deficiency anemia, B(12)/folate deficiency, and treated and untreated celiac disease. Enterocytes isolated from all groups showed 1400W-inhibitable Ca2+-independent NOS activity with a pH level and temperature optimum of 9.4 and 37 degrees C, respectively. Western blotting showed that enterocytes expressed the inducible NOS protein and proteins with nitrated tyrosine residues, the latter being indicative of nitric oxide-driven peroxynitrite and/or free-radical damage. Endothelial NOS was seen only in the lamina propria. Patients with celiac disease had higher NOS activity than other patient groups. Treatment of the condition led to a fall in activity. Enzyme-linked immunosorbent assay demonstrated cGMP production by the enterocyte fraction, but cGMP levels did not correlate with NOS activity. These results suggest that inducible NOS is constitutively expressed in human duodenal enterocytes, is increased in patients with untreated celiac disease, and is partially corrected when such patients are treated. We found no evidence to support a role for nitric oxide in the formation of cGMP within the small intestine. Furthermore, we were unable to demonstrate a role for peroxynitrite/free radical damage in the pathophysiology of celiac disease.