Should curative surgery be attempted in patients with cancer of the main stem bronchus?

Among tumors of the lung, main stem bronchial cancer offers a particularly unfavorable prognosis, probably because of its rapid extension to the segmental bronchi, trachea, and extrapulmonary structures. However, analysis of data gathered by the End Results Group indicates that survival among those patients with main stem bronchial cancer whose tumor was resected was virtually the same as that of patients with resectable lung cancer of other sites. From these data it is impossible to assess what role, if any, the resection itself played, and a randomized trial would be necessary to determine whether resection improves the probability of patient survival. On the other hand, it is not now advisable to deny resection to patients with operable main stem bronchial tumors (except oat cell tumors) on the basis of the available nonexperimental evidence alone.     

Optimization of the nutrient medium for Actinomyces spheroides--producer of proteolytic enzymes with fibrinolytic activity

Optimization of the medium for growing Actinomyces spheroides producing proteolytic exoenzymes with the fibrinolytic activity was performed by the method of mathematical planning. The composition of the medium is as follows (%): glucose 7.1, sodium citrate, trisubstituted, 0.48; (NH4)2SO4, 0.15; MgSO4, 0.575; KH2PO4, 0.2; ZnSO4, 0.001; FeSO4, 0.002. The fibrinolytic activity of the cultural broth on this medium is three times as high as on the initial medium (7142 units). Changes in the ratio between components of the medium lead to changes in the ratio between the fibrinolytic and caseinolytic activities. Therefore, Act. spheroides, strain 1, produces exoenzymes which differ by their substrate specificity. The ratio between the fibrinolytic and caseinolytic activities of the complex on the optimized medium is twice as high as on the initial medium.     

Effect of chromium(VI) on bacterial kinetics of heterotrophic biomass of activated sludge

The effect of hexavalent chromium, Cr(VI), on the maximum specific growth rate, mu(m) and biomass yield, Y(H), of heterotrophic biomass was studied in batch tests conducted under high (= 10) and low (= 1.5) substrate-to-biomass ratios (S0/X0). The effects of sludge age and biomass acclimatization to Cr(VI) on the bacterial kinetics were also studied. The mu(m) values were determined by measuring oxygen uptake rate (OUR) and volatile suspended solids (VSS) increase. Cr(VI) concentrations equal or greater than 10 mg l(-1) inhibited the growth of unacclimatized activated sludge and caused a significant decrease in mu(m) and Y(H) values. The acclimatization of biomass and the selection of a high operating sludge age reduced the inhibitory effect of Cr(VI). At a sludge age of 20 days, Cr(VI) concentrations of <10 mg l(-1) stimulated bacterial growth as evidenced by an increase in both the mu(m) and Y(H) values. Determining mu(m) values by OUR and VSS methods, revealed that the presence of Cr(VI) in unacclimatized biomass caused an inhibitory effect mostly on substrate oxidation, while in acclimatized biomass, anabolic pathways were inhibited more.     

Development and Validation of an ETAAS Method for the Determination of Tin in Canned Tomato Paste Samples

The determination of tin in canned food became very important in the last few years since it gives information about the contamination process helping to increase canned food quality and safety. The present work describes the development of a method for the determination of tin in canned tomato paste by electrothermal atomic absorption spectrometry in order to investigate the influents of (1) the industrial sample pretreatment procedure of canned tomato paste and (2) the type of materials used in packaging, on the total concentration of tin in canned tomato paste samples. For method validation, precision (repeatability and reproducibility) and accuracy (by recovery tests) have been assessed as performance criteria. The calculated recoveries ranged between 87.9% and 91.9%. The calculated expanded uncertainties based on the EURACHEM/CITAC Guidelines achieved from three different concentration levels were also calculated. The obtained results indicated that the method is efficiently and properly implemented. The validated method was applied for tin concentration determination in canned tomato paste purchased from the local market. In all analyzed samples, tin concentrations levels were lower than the maximum permissible value recommended by the European Regulation.