PARTIAL PURIFICATION AND CHARACTERIZATION OF A THERMOSTABLE TRYPSIN FROM PYLORIC CAECA OF TAMBAQUI (COLOSSOMA MACROPOMUM)

A 38.5 kDa alkaline protease from pyloric caeca of tambaqui (Colossoma macropomumj, a tropical freshwater fish, was partially purified in three steps: thermal treatment (45Cfor 30 min), salting‐out (ammonium sulfate at 40–80% of saturation) and gel filtration (Sephadex G‐75), The purification and yield were 51.2‐fold and 40%, respectively. The effects of pH, temperature, inhibitors, and substrates on proteolytic activities of partially purified enzyme were investigated. The optimum pH was 9.5, while the optimum temperature was 60C. This alkaline proteolytic activity remained unaltered after 30 min incubation at 55C. Active site inhibition provided additional evidence that this activity is attributed to a trypsin‐like enzyme.     

ION LEVELS OF FRESH AND PROCESSED SPINACH USING ION CHROMATOGRAPHY

The anion (Cl^?, NO^?₃, So^2-₄, PO^3-₄, OX^2-) and cation (Na⁺, K⁺, NH4⁺) composition of raw, frozen and canned spinach samples was determined by Ion Chromatography (IC). In general, the levels of these ions were determined after typical food processing operations. Important for its health-related and nutritional point of view is the observation that nitrate levels decreased by about 50% with losses of 15% in total organic nitrogen after typical commercial processing methods.     

CHARACTERIZATION OF STOMACH AND PYLORIC CAECA PROTEINASES OF TAMBAQUI (COLOSSOMA MACROPOMUM)

The effects of pH, temperature, inhibitors, and substrates on proteolytic activities of crude extracts from the stomach, liver, pyloric caeca, and intestines of Colossoma macropomum were investigated. The highest acid and alkaline proteolytic activities were found in stomach and pyloric caeca, respectively. The optimum pH for the acid and alkaline proteases were 1.8 and 7.0–9.0, respectively, while the optimum temperatures were 35C and 65C. This alkaline protease thermal stability remained unaltered after 90 min incubation at 55C. A pepsin‐like protease was responsible for most of the acidic proteolytic activity (Pepstatin A inhibited approximately 90%), whereas PMSF inhibited about 40% of the alkaline protease. The alkaline proteolytic activity has attractive thermal properties for industrial applications.     

Is ionic dialysance useful for early detection of vascular access dysfunction? Six illustrative cases

Continuous ionic dialysance monitoring is a useful clinical tool to determine the dialysis dose in real time in each hemodialysis session. We followed up 49 patients for 16 months. Six patients with a Kt reduction of ≥20% in >3 consecutive hemodialysis sessions were identified. Fistulography demonstrated significant stenosis in all 6 patients. Angioplasty was performed in 5 with an excellent angiographic result and optimal Kt levels were restored. Unexplained and persistent Kt reduction in patients with stable chronic kidney disease under hemodialysis could represent, together with an accurate vascular access examination, a practical and additional indirect method for the early detection of vascular access dysfunction.     

ON THE PREDICTION OF HEATS OF VAPORIZATION OF PURE COMPOUNDS

An expression to predict the values of the latent heat of vaporization of pure compounds at their normal boiling point has been developed. A knowledge of the critical temperature, critical pressure, normal boiling point and acentric factor of the compound coupled with the use of generalized correlations for second virial coefficient and liquid molar volume allows to obtain good estimates, particularly for alcohols and ketones. Results for 71 various substances are compared with experimental values and with the results of eight other equations available in the literature. The possibility of using the calculated heats of vaporization at the normal boiling point to estimate values at other temperatures is discussed.