Serum immunoglobulin free light chains in patients with monoclonal gammapathies.

Serum concentrations of κ- and λ-free light chains and their ratios were compared in 126 patients with monoclonal gammapathies (age 23-80 years) and 60 normal subjects (25-82 years). The main group included patients with intact immunoglobulin multiple myeloma, Bence Jones multiple myeloma, nonsecreting multiple myeloma, plasmocytoma, and monoclonal gammapathy of unknown origin. The accuracy of the method was evaluated by the analysis of 3 serum specimens with different concentrations of κ- and λ-free light chains. The variability of the method did not surpass the coefficient of variations permissible for this kind of analysis (10%). The new immunochemical method is characterized by high analytical sensitivity 100-fold surpassing that of electrophoretic methods. High concentrations of free light chains were most often found in the sera of patients with multiple myeloma with intact immunoglobulin secretion, Bence Jones multiple myeloma, and plasmocytoma. The diagnostic sensitivity of measurements of serum free light chains by the immunoturbidimetric method attained 90.5%. Combination of this method with serum protein electrophoresis and immunofixation resulted in detection of monoclonal gammapathy in 98.8% cases. These data indicate high specificity and analytical and diagnostic sensitivity of the immunoturbidimetric method for measurement of serum free light chains.

Clinical and biochemical aspects of the carcinoid syndrome in neuroendocrine tumors of the abdominal and retroperitoneal organs and its impact for the disease prognosis.

Overall and relapse-free survival of 238 patients with neuroendocrine tumors of the abdominal and retroperitoneal organs was evaluated with consideration for the presence of the carcinoid syndrome. The incidence of the carcinoid syndrome was 15.6%. The presence of the carcinoid syndrome was inessential for survival and relapse prognosis in patients with neuroendocrine tumors of the abdominal and retroperitoneal organs. A trend to the development of earlier relapses was noted in patients with this syndrome. Diarrhea was found to be a prognostically unfavorable factor. The time of the carcinoid syndrome development was prognostically significant in patients with malignant neuroendocrine tumors. The mean secretion of epinephrine, norepinephrine, and dopamine with daily urine was significantly higher in patients with the carcinoid syndrome. A significant positive correlation between urinary excretion of catecholamines was detected (r=0.53; p<0.05).

Purification and characterization of the constitutive form of laccase from the basidiomycete Coriolus hirsutus and effect of inducers on laccase synthesis.

An isolate of Coriolus hirsutus constitutively expresses substantial amounts of extracellular laccase on a defined growth medium. The most efficient inducer of extracellular laccase synthesis was syringaldazine, which increased the enzyme yield by 1000% at a concentration of 0.11 microM. The constitutive form of the enzyme was purified 312-fold. Laccase from C. hirsutus, with an estimated molecular mass of 55 kDa and pI of 4.0, is a monomeric glycoprotein containing 12% carbohydrate consisting of mannose and N-acetylglucosamine. The laccase was found to contain 3.9-4.1 copper atoms per molecule. The absorption spectrum shows a maximum at 610 nm and a shoulder at 330 nm, which is typical of laccase possessing type 1 and type 3 copper atoms. The parameters of the first type of copper were determined by EPR as g perpendicular=2.046 and g parallel=2.200, A parallel=8.103 x 10(-3) cm-1. Laccase was found to be a pH-stable and thermostable enzyme. With organic substrates it exhibits a pH optimum of 4.5, but with the inorganic substrate K4[Fe(CN)6] this decreased to 3.5. The highest efficiency of catalysis was observed with sinapinic acid as the substrate. The kinetic constants kcat and Km of this reaction were 578 s-1 and 24 microM respectively. It was established that the kinetics of the assayed reaction shows a Ping Pong mechanism.