Effect of the addition of nitrogen sources to cassava fiber and carbon-to-nitrogen ratios on Agaricus brasiliensis growth.

The same substratum formulation to grow Agaricus bisporus has been used to grow Agaricus brasiliensis since its culture started in Brazil. Despite being different species, many of the same rules have been used for composting or axenic cultivation when it comes to nitrogen content and source in the substrate. The aim of this study was to verify the mycelial growth of A. brasiliensis in different ammonium sulfate and (or) urea concentrations added to cassava fiber and different carbon-to-nitrogen (C:N) ratios to increase the efficiency of axenic cultivation. Two nitrogen sources (urea and (or) ammonium sulfate) added to cassava fiber were tested for the in vitro mycelial growth in different C:N ratios (ranging from 2.5:l to 50:l) in the dark at 28 degrees C. The radial mycelial growth was measured after 8 days of growth and recorded photographically at the end of the experiment. Nitrogen from urea enhanced fungal growth better than ammonium sulfate or any mixture of nitrogen. The best C:N ratios for fungal growth were from 10:l to 50:l; C:N ratios below 10:l inhibited fungal growth.

Heterogeneity of nuclear DNA pattern and its relationship with cell cycle activity parameters in multinodular goitre.

OBJECTIVE: Recent studies suggest that the malignancy rate in multinodular goitre is not significantly different from that observed in solitary nodules and that chromosomal aberrations are not infrequent in multinodular goitre. To further investigate this topic we determined the DNA pattern in multinodular goitres. DESIGN: DNA ploidy and cell cycle activity parameters were determined in multinodular goitres. PATIENTS: We evaluated 235 patients (185 female, 50 male, mean age 52 +/- 13 years), who had undergone thyroidectomy; 11 of them harboured occult differentiated microcarcinoma. MEASUREMENTS: DNA index (DI), coefficient of variation of G0/G1 phase (CV), percentage of cells in S phase (%S) and in G2+M phase (%G2-M) and proliferative index (PI = %S+%G2-M) were determined by flow cytometric analysis (FCM) in tissue samples taken from 3 different areas of the thyroid gland. RESULTS: Aneuploid DNA was found in 50 goitres without carcinoma (22.3%) and in 5 goitres with carcinoma (45.5%). The mean PI of euploid cells in the goitre without carcinoma was significantly higher in the goitres with an aneuploid component compared to the goitres without aneuploidy (10.8 +/- 1.3 SEM vs 6 +/- 0.32; P +/- 0.001). Also, the percentage difference between maximal and minimal PI found within each goitre (delta PI %) was higher in the former group (373 +/- 49 SEM vs 142 +/- 11.3; P < 0.0001). The PI was significantly higher in goitres with carcinoma compared to the goitres without carcinoma (12.9 +/- 3.2 SEM vs 7.07 +/- 0.40; P < 0.05). CONCLUSIONS: The findings of increased proliferation rate in goitres with an aneuploid or neoplastic component suggests that some factors involved in goitrogenesis could also be responsible for the development of chromosomal aberrations and/or for the selection of cellular clones endowed with high growth potential.

Generation of human monoclonal antibodies by transformation of lymphoblastoid B cells with ras oncogene.

Human monoclonal antibodies (hu-mAbs) of predetermined specificity and isotype are potentially important for a variety of applications, including therapy and diagnosis. Their efficient generation, however, is still hampered by technical difficulties. Even the most established approaches to the generation of hu-mAbs, i.e., B cell immortalization by Epstein-Barr virus (EBV) and/or fusion with appropriate myeloma cell lines, are characterized by a relatively low efficiency. It has been shown that expression of activated Ha- or N-ras oncogenes causes the malignant transformation and plasmacytoid differentiation of EBV-immortalized lymphoblastoid cell (LC) lines, suggesting that activated ras oncogenes can convert LC lines into effective hu-mAb producers. We have used retroviral vector-mediated gene transfer to introduce an activated Ha-ras (v-ras) oncogene into four distinct LC lines producing hu-mAbs of different classes (IgM and IgG) and specificities (to human insulin, human thyroglobulin and rabies virus glycoprotein). The cloning efficiency and antibody secretion of these ras-transformed LC (ras-LC) lines were compared with those of the hybrid LC (hyb-LC) lines generated by fusing the same parental LC lines with the Ig non-secretor F3B6 human-mouse hybrid cells. ras-LC lines were comparable to their hybrid counterparts in either parameter tested. This, together with the relatively higher efficiency of the method, suggests that ras transformation may constitute a valid alternative to the currently available technologies for hu-mAbs production from LC lines.