Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Expression of αvβ6integrin in oral leukoplakia

The distribution of αvβ6integrin was examined in oral leukoplakia, lichen planus and squamous cell carcinomas using immunohistochemistry. Controls included oral mucosal wounds, chronically inflamed and normal oral mucosa. Integrins β1, β3, β4, β5, fibronectin and tenascin were also studied. The integrin αvβ6was highly expressed throughout the whole lesion of 90% of the squamous cell carcinomas but was not present in any of the normal specimens. αvβ6integrin was also expressed in 41% of the leukoplakia specimens, and 85% of the lichen planus samples, but in none of the tissues with inflammatory hyperplasia or chronic inflammation. The expression of β1 integrins was localized in the basal layer, and that of the β4at the cell surface facing the basement membrane of all specimens. The integrins β3and β5were absent from all normal and leukoplakia specimens. Fibronectin and tenascin were present in the connective tissue underneath the epithelium of all the sections, and their expression was similar in both αvβ6-positive and αvβ6-negative tissues. A group of 28 leukoplakia patients were followed 1–4 years after first diagnosis. In this group, initially αvβ6integrin-positive leukoplakia specimens had high tendency for disease progression while αvβ6-negative specimens did not progress. These results suggest that the expression of αvβ6integrin could be associated in the malignant transformation of oral leukoplakias. © 2000 Cancer Research Campaig

Giant magnetoresistance effect in la0.8sr0.2mno3 thin films

The resistivity and magnetoresistivity behavior of highly oriented La0.8Sr0.2MnO3 thin films have been studied in the temperature range 4.2 K less than or equal to T less than or equal to 300 K, in magnetic fields up to 4.5 T. The films exhibit a temperature-dependent giant magnetoresistance (GMR) effect, with a maximum GMR of the order of similar to 60% in a field of 4.5 T, at 210 K. The temperature dependence of the magnetization shows that the films are ferromagnetic below similar to 200 K. The peak in GMR and zero-field resistivity is observed to lie near the magnetic transition temperature. Our results show that the functional dependence of the magnetoresistivity on the field H, changes from linear at 4.2 K to root H at 210 K. Above the Curie temperature, on the other hand, it shows a H-2 dependence. The resistivity, magnetoresistivity, and magnetization behavior of the present films exhibit a strong correlation as seen through their temperature dependences

Giant magnetoresistance studies on La-(0.8-x)R(x)Sr(0.2)MnO(3) thin films (R=Pr,Nd,Gd,Ho)

The effect of substituting La by a smaller lanthanide element (R) in La(0.8-x)R(x)Sr(0.2)MnO(3) (x = 0.1; R = Pr, Nd, Gd, Ho) thin films on the resistivity (rho) and giant magnetoresistance (GMR) behaviour was studied. The magnitude of GMR shows a maximum as a function of temperature. The temperature at which the maximum value of GMR is observed was found to shift systematically towards higher temperatures (from 210 to 300 K) as the size of the substitution ion increases from Ho to Pr, rho(T) also shows a maximum which shifts to higher temperatures as the size of the substitution ion increases. The zero-field resistivity shows a systematic decrease as the size of R(3+) increases. This result is explained qualitatively by invoking the interrelation between the conduction electron hopping probability and the Mn-O-Mn bond angle distortion which, in turn, is governed by the size of the substitution ion. Our results show that the size of the rare earth substitution ion can play an important role in tailoring the resistivity and GMR behaviour of La-R-Sr-Mn-O thin films, particularly for room temperature applications