CLIC-1 functions as a chloride channel when expressed and purified from bacteria.

CLIC-1 is a member of a family of proteins related to the bovine intracellular chloride channel p64 which has been proposed to function as a chloride channel. We expressed CLIC-1 as a glutathione S-transferase fusion protein in bacteria. The fusion protein was purified by glutathione affinity, and CLIC-1 was released from its fusion partner by digestion with thrombin. After further purification, CLIC-1 was reconstituted into phospholipid vesicles by detergent dialysis. Chloride permeability of reconstituted vesicles was assessed using a valinomycin dependent chloride efflux assay, demonstrating increased vesicular chloride permeability with CLIC-1 compared with control. CLIC-1-dependent chloride permeability was inhibited by indanyloxyacetic acid-94 with an apparent IC(50) of 8.6 micrometer. The single channel properties of CLIC-1 were determined using the planar lipid bilayer technique. We found that CLIC-1 forms a voltage-dependent, Cl-selective channel with a rectifying current-voltage relationship and single channel conductances of 161 +/- 7.9 and 67.5 +/- 6.9 picosiemens in symmetric 300 and 150 mm KCl, respectively. The anion selectivity of this activity is Br approximately Cl > I. The open probability of CLIC-1 channels in planar bilayers was decreased by indanyloxyacetic acid-94 with an apparent IC(50) of 86 micrometer at 50 mV. These data convincingly demonstrate that CLIC-1 is capable of forming a novel, chloride-selective channel in the absence of other subunits or proteins.

A prospective randomized study of preoperative nutritional supplementation in patients awaiting elective orthotopic liver transplantation.

BACKGROUND: Poor nutritional status is common among patients awaiting orthotopic liver transplantation and is associated with poor outcome. METHODS: This prospective randomized controlled trial examined the effect of pretransplant nutritional supplementation on the outcome of patients undergoing liver transplantation. Of 82 consecutive patients with mid-arm muscle circumference <25th percentile, 42 received enteral supplementation, and the remainder acted as the control group. The supplemented group received a calorie-dense enteral feed taken daily (in addition to diet) until transplantation. Nutritional status was monitored by upper arm anthropometric measurements and handgrip strength. Dietary intake was calculated from 5-day food diaries. RESULTS: Supplementation improved mid-arm circumference, mid-arm muscle circumference, and grip strength. Pretransplant nutritional status was not associated with posttransplant sepsis or major complications. Preoperative grip strength of <85% of normal values was predictive of increased incidence of posttransplant major complications. Supplementation did not affect outcome, although there were more deaths in the control group (seven deaths before and two deaths after transplant) than there were in the supplemented group (two deaths before and three deaths after transplant). There was no difference in overall survival (P = 0.075). CONCLUSIONS: Enteral supplementation improved some parameters of nutritional status pretransplant. Dietary intake of patients in the two groups was similar at transplant. Nutritional supplementation has not increased nutritional intake, although this may reflect the importance of regular dietetic input and support, rather than suggesting that nutritional supplementation is ineffective. Supplementation had no effect on outcome of liver transplantation.

Prospective randomized comparison of two different sized percutaneous endoscopically placed gastrostomy tubes.

We performed a prospective randomised study of two different sized percutaneous endoscopic gastrostomy (PEG) tubes to determine if tube size influenced the incidence of PEG-related complications. Patients were given prophylactic cefuroxime, if not already on antibiotics at the time of PEG insertion. Fifty-two PEGs were successfully placed, 26 in each group. Most patients who required a PEG had suffered a cerebrovascular event (82.7%). There were no procedure-related deaths. The mean ages (standard deviation) for the 12 and 20 French Gauge (FG) groups were 78.7 (8.9) and 73.9 (14.4) years, respectively, with no statistical difference. There were no significant differences in mortality (9 deaths in the 12 FG and 11 deaths in the 20 FG groups), number of peristomal infections (8 infections in the 12 FG and 12 infections in the 20 FG groups), episodes of leakage (12 leakages in the 12 FG and 17 leakages in the 20 FG groups) or tube blockage (2 blockage episodes in the 12 FG and 1 blockage episode in the 20 FG groups) between the two groups over a follow-up period of 190 days. The incidence of insertion- and feeding-related complications was thus not influenced by tube size. As the smaller PEG tubes were easier and less traumatic to insert we conclude that there are grounds for considering the more widespread use of the narrower diameter 12 FG PEG tubes.

Influence of three different fiber-supplemented enteral diets on bowel function and short-chain fatty acid production.

BACKGROUND: Dietary fiber is known to influence bowel habit and gastrointestinal mucosal cell morphology and function. large-bowel function is particularly influenced by insoluble, poorly fermentable fiber sources, whereas mucosal function is affected by fiber sources that are soluble and highly fermentable. The aim of the present study was to compare bowel function during consumption of a self-selected diet, a fiber-free enteral diet, and three polymeric enteral diets, each supplemented with a fiber with different fermentation characteristics. The fiber sources used were oat, soy oligosaccharide, and soy polysaccharide. METHODS: Seven healthy subjects consumed four diets in random order for 4 to 7 days. These were a self-selected diet, a 2-L polymeric enteral diet, and a 2-L polymeric enteral diet supplemented with 15 g of total dietary fiber per liter derived from either soy oligosaccharide fiber (75 g/L) or oat fiber (15 g/L). An additional six healthy subjects were randomly assigned to three diets (4 to 7 days): a self-selected diet, a 2-L polymeric enteral diet, or the same 2-L polymeric enteral diet supplemented with 20 g of soy polysaccharide fiber per liter (15 g of total dietary fiber per liter). Bowel function was assessed by measuring whole-gut transit time, mean daily stool wet weights, and bowel movement frequency per day. Fermentation characteristics of the different fiber sources were determined quantitatively and qualitatively by measuring short-chain fatty acids produced during in vitro stool culture. RESULTS: Total short-chain fatty acid and butyric acid production with soy oligosaccharide fiber were significantly higher compared with values observed for soy polysaccharide fiber (p < .003), oat fiber (p < .005), and self-selected (control) diet (p < .003). Compared with the fiber-free diet, consumption of the soy polysaccharide, oat, and soy oligosaccharide-fiber-supplemented enteral diets did not significantly (p > .05) alter whole-gut transit time or stool wet weight. However, bowel frequency was significantly improved by consumption of the soy polysaccharide-fiber-supplemented diet but not the oat fiber or soy oligosaccharide-fiber-supplemented diets. CONCLUSION: Compared with a fiber-free polymeric enteral diet, the daily consumption of an enteral diet supplemented with 30 g of total dietary fiber per day derived from a poorly fermentable oat fiber, a highly fermentable soy oligosaccharide fiber, or a moderately fermentable soy polysaccharide fiber has little impact, if any, on bowel function.

The effect of a fibre free and fibre supplemented polymeric enteral diet on normal human bowel function.

Although the effects of dietary fibre in a normal diet on intestinal function are well known, the effects of supplementing enteral diet with fibre on intestinal function are not so clear. The aims of the present study were two fold: firstly to compare intestinal function during ingestion of a self selected diet and fibre free polymeric enteral diet and secondly to investigate the effect of adding the fibre source, soy polysaccharide to the same polymeric diet, on bowel function. Six healthy subjects were randomly assigned to 3 treatment periods (7 days) of a self selected diet (SSD), 2 l polymeric enteral diet (ED), or 2 l of the same polymeric enteral diet supplemented with 20 g/l of soy polysaccharide fibre (SPED). Parameters measured were bowel frequency/day, mean daily wet stool weights and whole gut transit time. Highest stool wet weights (g/24 h +/- SEM) were obtained from subjects consuming a SSD (180.3 +/- 30.6). This was significantly higher (p < 0.02) than those consuming an ED (81.9 +/- 14.5) but not a SPED (123 +/- 22.3). Whole gut transit (h +/- SEM) on a SSD (47 +/- 5.9) was significantly (p < 0.05) quicker than on an ED (73 +/- 4.9), but not significantly different from those ingesting a SPED (54 +/- 5.5). Bowel frequency/day (+/- SEM) in subjects consuming a SPED (1.0 +/- 0.1) was significantly (p < 0.02) higher than in subjects ingesting an ED (0.8 +/- 0.1) but was not significantly different when compared to a SSD (1.0 +/- 0.2). We conclude that ingestion of an ED results in significantly longer whole gut transit time, significantly decreased daily stool wet weights and decreased bowel frequency when compared to a SSD. The ingestion of 30 g of soy polysaccharide in a polymeric enteral diet not only tends to normalise whole gut transit time and daily stool wet weights, but also significantly increases bowel frequency when compared with values seen during the consumption of a fibre free polymeric enteral diet.

Is oropharyngeal anaesthesia with topical lignocaine useful in upper gastrointestinal endoscopy?

The aim of this study was to determine whether patients' tolerance of upper gastrointestinal endoscopy is related to the dose of lignocaine spray used for oropharyngeal anaesthesia and to measure plasma concentrations at these doses. Sixty consecutive patients undergoing routine upper gastrointestinal endoscopy with sedation were randomized to receive lignocaine spray 50 mg (Group A), 100 mg (Group B) or 200 mg (Group C). Patient, endoscopist and endoscopy nurse were unaware of the variation in dose used. Each patient's tolerance of the intubation and of the remainder of the gastroscopy was assessed independently by the patient, endoscopy nurse, and endoscopist using a visual analogue scale. Plasma lignocaine concentration was measured at 20, 40, 60 and 80 min after administration of the spray. Fifty (83%) patients were unable to recall either the intubation, or the procedure. On the endoscopy nurse's assessment, the patients in Group B tolerated the intubation better than those in Group A, and Groups B and C tolerated the remainder of the gastroscopy better than those in Group A. On the endoscopist's assessment, Groups B and C tolerated the remainder of the gastroscopy better than Group A. There were fewer gags per min in Groups B and C compared to Group A. Mean plasma lignocaine concentrations showed a dose-dependent absorption of the spray, but none exceeded the potentially toxic level of 5 mg/L.