Reactively sputtered MoO3 films for ammonia sensing

We report the gas-sensing properties of ion-beam sputter deposited MoO₃ thin-films. The change in the DC conductivity was measured in dry N₂ with 10% O₂ in the presence of up to 490 ppm of NH₃, NO, NO₂, C₃H₆, CO and H₂. At ∼440 °C the film was found to be very sensitive to NH₃, with 490 ppm increasing the conductivity by approximately a factor of 70. This was approximately 17 times greater than the response to the other gases. The NH₃ response was strongly affected by the accompanying levels of O₂, NO₂ and H₂O. For example, changing the accompanying O₂ levels from 1% to 20% decreased the NH₃ response by approximately a factor of 20. Similarly, the presence of 100 ppm NO₂ (in 10% O₂) decreased the NH₃ response by approximately a factor of three, and 1% water vapor decreased it by more than a factor of two. The NH₃ response, however, was relatively unaffected by 100 ppm of accompanying NO, C₃H₆, CO or H₂. XPS measurements show that the increased conductivity in the presence of NH₃ was also accompanied by a partial reduction of the surface MoO₃. We observed an increase in the resistance of the films after extended time at elevated temperatures.     

Biodoped Ceramics: Synthesis, Properties, and Applications

This feature article focuses on biodoped ceramics. These are inorganic materials in which biological materials are incorporated, thus adding new functionality to them. A brief overview of the prominent synthesis techniques for biodoped ceramics, with emphasis on modified sol–gel processes for metal oxide matrices, is given first. Theoretical treatments of the encapsulation of biologicals within a porous ceramic matrix are reviewed. Experimental studies of the stability and dynamics of protein entrapment in silica and other ceramic matrices are also discussed. Finally, key applications of biodoped ceramics in biochemical species detection, bio-catalysis, and drug delivery are presented.     

Annealing studies of γ-titanium aluminides alloyed with light elements for creep strengthening

A fully-lamellar γ-titanium aluminide alloy containing carbon and silicon additions has been found to have superior creep resistance. The aging characteristics of this alloy, which also contains Nb, Cr, and W, have been studied by means of transmission electron microscopy techniques and are correlated to the post-crept microstructures. Precipitation of carbides and silicides along γ/γ interlamellar boundaries was observed during aging and creep deformation. The driving force for the precipitation reaction is the accommodation of excess amounts of carbon and silicon which have limited solubility in the γ-matrix. For comparison, the aging behavior of a Ti-46.8Al (at%) alloy containing carbon and boron has been assessed. It is found that the lamellar grain size is significantly smaller than the alloy without boron, but that equiaxed γ-grains also form during aging. In this alloy, carbides are observed to precipitate homogeneously within γ-laths and equiaxed grains.     

Hospital experience and hospital mortality following partial pancreaticoduodenectomy in The Netherlands

OBJECTIVE: To analyse the effect of hospital experience on mortality after subtotal pancreaticoduodenectomy in the Netherlands. DESIGN: Retrospective evaluation. METHOD: Information on hospital mortality and pancreatic resection in 1994 and 1995 in the Netherlands was obtained from the National Medical Register. Subanalysis was carried out of surgical mortality by age and hospital experience. RESULTS: Approximately 50% of the pancreaticoduodenectomies in the Netherlands were performed in hospitals with limited experience (< 5 procedures per year). Hospital mortality was higher in small-volume hospitals than in hospitals with experience (> 25 procedures per year): in 1994 17.2 and 0% and in 1995 14.6 and 2.9%, respectively (p < 0.05). Mortality was higher in patients older than 70 years compared with patients younger than 55 (p < 0.05). CONCLUSION: There was a correlation between mortality after pancreaticoduodenectomy and hospital experience. Therefore these procedures should be performed in centres with experience.     

Increased concentrations of tumour necrosis factor (TNF) and soluble TNF receptors in biliary obstruction in mice; soluble TNF receptors as prognostic factors for mortality

Erythema nodosum leprosum (ENL) is a serious complication of lepromatous (L) disease in leprosy. We have previously shown that of the four IgG subclasses, IgG1 and IgG3 Mycobacterium leprae-specific antibodies are significantly lower in leprosy patients during ENL reaction compared with untreated L patients. To see if this decrease results from a down-regulation of antibody synthesis during ENL, the frequency of antibody-secreting B cells (ABSC) in the blood compartment was determined by ELISPOT and related to serum immunoglobulin concentrations (microgram/ABSC). Control groups consisted of 16 patients with stable L disease and 32 healthy endemic controls (EC). Paired samples were analysed during acute ENLS (n = 13) and after the reaction had subsided to identify changes associated with ENL. Polyclonal (PC) IgG1 was elevated in L patients compared with EC (325 micrograms versus 180 micrograms). Interestingly, patients during acute ENL showed concentrations higher than L patients (419 micrograms), which decreased after the reaction had subsided (260 micrograms), indicating the transient nature of the antibody response. IgG2 antibodies showed the reverse trend and were lower during ENL and increased after the reaction had subsided. The mean concentrations for PC IgG3 and IgG4 antibodies were similar during ENL and after the reaction had subsided. Thus, decrease in M. leprae-specific IgG1 and IgG3 antibodies is not related to down-regulation of B cell responses. Identification of factors which regulate PC IgG1 antibody synthesis may provide additional insights into determinants of ENL reactions.     

Endoscopic sclerotherapy versus variceal ligation in the long-term management of patients with cirrhosis after variceal bleeding. A prospective randomized study

BACKGROUND/AIMS: Long-term endoscopic injection sclerotherapy of oesophageal varices prevents rebleeding in patients with cirrhosis surviving an acute variceal bleeding episode. However, this treatment is associated with a substantial complication rate. Endoscopic band ligation is a newly developed technique in an attempt to provide a safer alternative. The aim of this study was to compare the efficacy and safety of injection sclerotherapy versus variceal ligation in the management of patients with cirrhosis after variceal haemorrhage. METHODS: Seventy-seven patients with cirrhosis who proved to have oesophageal variceal bleeding were studied. After initial control of haemorrhage by sclerotherapy, 40 of the patients were randomly assigned to sclerotherapy and 37 to ligation. Both procedures were performed under midazolam sedation at intervals of 7-14 days until all varices in the distal oesophagus were eradicated or were too small to receive further treatment. RESULTS: The eradication of varices required a lower mean number of sessions with ligation (3.7 +/- 1.9) than with sclerotherapy (5.8 +/- 2.7, p = 0.002). The mean duration of follow-up was similar in both groups (15.6 months +/- 7.3 and 15 +/- 7.4, respectively). The proportion of patients remaining free from recurrent bleeding against time was significantly higher in the ligation group as compared to the sclerotherapy group (chi 2 = 3.86, p = 0.05). Only 13 patients (35%) developed complications in the ligation group as compared to 24 (60%, p = 0.05) in the sclerotherapy group. The mortality rate was similar in both groups (20% and 21%, respectively). CONCLUSIONS: Variceal ligation is better than sclerotherapy in the long-term management of patients with cirrhosis after variceal haemorrhage which was initially controlled with sclerotherapy.     

Comparative effects of enteric-coated pancreatin microsphere therapy after conventional and pylorus-preserving pancreatoduodenectomy

BACKGROUND: A comparative study was performed between patients with exocrine pancreatic insufficiency after conventional pancreatoduodenectomy (Whipple's procedure) and pylorus-preserving pancreatoduodenectomy (PPPD). In these patients the pharmacodynamics of 2-mm enteric-coated pancreatin microspheres (ECPMs) and their gastric transit time in relation to that of a solid meal were investigated. The efficacy of ECPM preparations may differ after Whipple's procedure compared with PPPD, because the latter procedure does not include gastrectomy. METHODS: Gastric transit was assessed by double-isotope scintigraphy. A pancake meal was labelled with 99mTc. ECPMs were cold-labelled with 170Er and neutron activated shortly before ingestion to enable imaging with a gamma camera. Intraluminal pancreatic enzyme activity was assessed during a 6-h period with two indirect tests: the cholesteryl [14C]octanoate breath test and the N-benzoyl-L-tyrosyl-p-aminobenzoic acid-p-aminosalicylic acid (NBT-PABA-PAS) test. RESULTS: In patients who had Whipple's procedure, the gastric transit time of ECPMs and of the pancake meal was not significantly different. The outcome of the indirect pancreatic function tests during enzyme supplementation was comparable, and not significantly different, from that in healthy volunteers. In patients who had PPPD, however, the gastric transit time of microspheres was greatly delayed compared with that of the pancake meal (P < 0.05). Improvement in the outcome of the indirect pancreatic function tests during enzyme supplementation was much less and remained well below that of healthy volunteers (P < 0.05). CONCLUSION: In cases of exocrine pancreatic insufficiency after Whipple's procedure, 2-mm ECPM treatment adequately restores pancreatic enzyme activity. Following PPPD, however, ECPM treatment is often ineffective because the microspheres are retained in the stomach. In these patients, use of conventional powdered pancreatin enzyme preparations may improve the efficacy of treatment.     

Preoperative biliary drainage, colonisation of bile and postoperative complications in patients with tumours of the pancreatic head: a retrospective analysis of 241 consecutive patients

OBJECTIVE: To analyse the outcome of preoperative biliary drainage in patients being operated on for a tumour in the pancreatic head. DESIGN: Retrospective study. SETTING: University hospital, The Netherlands. SUBJECTS: Consecutive series of 241 patients. MAIN OUTCOME MEASURES: Decline in bilirubin concentrations and bacterial contamination of bile as a result of preoperative drainage. Incidence of postoperative complications in patients who underwent preoperative drainage and those who did not. RESULTS: 184/241 patients underwent preoperative biliary drainage. Endoscopic drainage was the most effective, shown by a median reduction in bilirubin concentrations of 82%, 74%, and 50% after endoscopic drainage (n = 149), papillotomy (n = 25) and external drainage (n = 10), respectively. Bacterial contamination of bile was significantly more common when an endoprosthesis was used, but did not result in a higher rate of infective complications. 163 Whipple's resections, 33 total pancreatectomies, and 45 biliary-enteric bypasses were performed. 137/241 (57%) patients had postoperative complications. There was no significant difference in the incidence of postoperative complications between patients who had preoperative biliary drainage and those who did not (p = 0.4).     

Nanostructured oxide-based selective gas sensor arrays for chemical monitoring and medical diagnostics in isolated environments

MoO3 and MoO3-WO3-based resistive type sensors/arrays have been used for the detection of toxic gaseous compounds important to environmental monitoring and to medical diagnostics. The responses of the sensing elements when exposed to 400 ppm of methanol, 10 ppm of isoprene, and 15 ppm of ammonia at temperatures between 400 degrees C and 500 degrees C have been assessed. A correlation was made between the crystallography of the nanostructured oxide sensing films and their relative gas selectivity to the analytes of interest. Arrays of selective sensing elements are proposed as valuable tools for the survival of humans in isolated environments and for space exploration.     

Prospective, randomized trial on the effect of cyclic versus continuous enteral nutrition on postoperative gastric function after pylorus-preserving pancreatoduodenectomy

OBJECTIVE: The effect of a cyclic versus a continuous enteral feeding protocol on postoperative delayed gastric emptying, start of normal diet, and hospital stay was assessed in patients undergoing pylorus-preserving pancreatoduodenectomy (PPPD). SUMMARY BACKGROUND DATA: Delayed gastric emptying occurs in approximately 30% of patients after PPPD and causes prolonged hospital stay. Enteral nutrition through a catheter jejunostomy is used to provide postoperative nutritional support. Enteral infusion of fats and proteins activates neurohumoral feedback mechanisms and therefore can potentially impair gastric emptying and prolong postoperative gastroparesis. METHODS: From September 1995 to December 1996, 72 consecutive patients underwent PPPD at the Academic Medical Center, Amsterdam. Fifty-seven patients were included and randomized for either continuous (CON) jejunal nutrition (0-24 hr; 1500 kCal/24 hr) or cyclic (CYC) enteral nutrition (6-24 hr; 1125 kCal/18 hr). Both groups had an equal caloric load of 1 kCal/min. The following parameters were assessed: days of nasogastric intubation, days of enteral nutrition, days until normal diet was tolerated orally, and hospital stay. On postoperative day 10, plasma cholecystokinin (CCK) levels were measured during both feeding protocols. RESULTS: Nasogastric intubation was 9.1 days in the CON group (n = 30) and 6.7 days in the CYC group (n = 27) (not statistically significant). First day of normal diet was earlier for the CYC group (15.7 vs. 12.2 days, p < 0.05). Hospital stay was shorter in the CYC group (21.4 vs. 17.5 days, p < 0.05). CCK levels were lower in CYC patients, before and after feeding, compared with CON patients (p < 0.05). CONCLUSIONS: Cyclic enteral feeding after PPPD is associated with a shorter period of enteral nutrition, a faster return to a normal diet, and a shorter hospital stay. Continuously high CCK levels could be a cause of prolonged time until normal diet is tolerated in patients on continuous enteral nutrition. Cyclic enteral nutrition is therefore the feeding regimen of choice in patients after PPPD.