Production of laccases in submerged process by <Emphasis Type="Italic">Pleurotus sajor-caju</Emphasis> PS-2001 in relation to carbon and organic nitrogen sources,antifoams and Tween 80

Some conditions in media composition for laccases production, such as different sources of carbon and organic nitrogen, antifoams and a surfactant, were studied in liquid cultures of Pleurotus sajor-caju strain PS-2001. Cultivation with fructose or glucose as carbon sources produced maximum enzyme activities of 37 and 36 U mL⁻¹, respectively. When sucrose was present in the medium, the best results were obtained using 5 g L⁻¹ of this carbohydrate, on the 11th day of the process, attaining laccase titres of 13 U mL⁻¹. In a medium without casein, practically no enzyme was produced during the experiments; among the sources of nitrogen studied, pure casein led to the highest titres of laccase activity. Different concentrations of pure casein and sucrose were also tested. As to the different concentrations of casein, the addition of 1.5 g L⁻¹ resulted in the highest titres of laccase activity. Negligible levels of manganese peroxidase activity were also detected in the culture medium. In low concentrations, polypropylene glycol or silicon-based antifoams and the surfactant Tween 80 have no significant influence on the formation of laccases by P. sajor-caju. However, enhanced concentration of polypropylene glycol negatively affected the production of laccases but favored the titres in total peroxidases, lignin peroxidase and veratryl alcohol oxidase.     

Genetic disassociation of autoimmunity and resistance to costimulation blockade-induced transplantation tolerance in nonobese diabetic mice

Curing type 1 diabetes by islet transplantation requires overcoming both allorejection and recurrent autoimmunity. This has been achieved with systemic immunosuppression, but tolerance induction would be preferable. Most islet allotransplant tolerance induction protocols have been tested in nonobese diabetic (NOD) mice, and most have failed. Failure has been attributed to the underlying autoimmunity, assuming that autoimmunity and resistance to transplantation tolerance have a common basis. Out of concern that NOD biology could be misleading in this regard, we tested the hypothesis that autoimmunity and resistance to transplantation tolerance in NOD mice are distinct phenotypes. Unexpectedly, we observed that (NOD x C57BL/6)F(1) mice, which have no diabetes, nonetheless resist prolongation of skin allografts by costimulation blockade. Further analyses revealed that the F(1) mice shared the dendritic cell maturation defects and abnormal CD4(+) T cell responses of the NOD but had lost its defects in macrophage maturation and NK cell activity. We conclude that resistance to allograft tolerance induction in the NOD mouse is not a direct consequence of overt autoimmunity and that autoimmunity and resistance to costimulation blockade-induced transplantation tolerance phenotypes in NOD mice can be dissociated genetically. The outcomes of tolerance induction protocols tested in NOD mice may not accurately predict outcomes in human subjects.     

Deuterium isotope effect on enantioselectivity in the Comamonas testosteroni quinohemoprotein alcohol dehydrogenase-catalyzed kinetic resolution of rac-2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane,solketal

Isotopic substitution provides an effective tool to probe the mechanism of enzyme-catalyzed reactions. To our knowledge, kinetic isotope effects on the enantioselectivity of enzymes have not been reported. We investigated the effect of deuterium substitution on the enantiomeric ratio, E, of PQQ-containing quinohemoprotein alcohol dehydrogenase, QH-ADH, from Comamonas testosteroni in the ferricyanide-coupled kinetic resolution of rac-2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane, solketal. Under otherwise identical conditions, we measured E=30 for solketal and E=6 for rac-2,2-dimethyl-4-[1,1-2H]hydroxymethyl-1,3-[5,5,4-2H]dioxolane, d(5)-solketal. It is proposed that isotopic substitution affects the relative kinetic weights of the initial hydron/deuteron transfer from substrate to cofactor and the subsequent proton/deuteron shift in the cofactor-product complex. The latter step becomes more important in the deuterated complex to the extent that the enantiomer discrimination in the first step is partially overruled.     

Bioimpedance analysis: a useful technique for assessing appendicular lean soft tissue mass and distribution.

The present study was aimed at evaluating the feasibility and reliability of lower limb skeletal muscle (SM) mass estimates obtained by bioimpedance analysis (BIA). BIA estimates were compared with the estimates obtained by dual-energy X-ray absorptiometry (DXA). Ten normal weight and 10 obese women had BIA and DXA evaluations. Lower limb SM mass was then derived from DXA appendicular lean soft tissue estimates. Lower limb SM mass and SM distribution were also estimated from BIA modeling that fits measured resistance values along the leg. SM mass (mean +/- SD) was 5.8 +/- 1.0 kg by BIA vs. 5.8 +/- 1.1 kg by DXA in normal weight subjects and 7.2 +/- 1.4 kg by BIA vs. 7.2 +/- 1.2 kg by DXA in obese subjects. Mean +/- SD of the absolute value of the relative error was 7.0 +/- 3.4 and 5.9 +/- 3.4% in the two groups, respectively. Similar results were obtained by using five resistance values for the analysis. In conclusion, the proposed BIA model provides an adequate means of evaluating appendicular SM mass.     

Multicenter evaluation of an enzyme immunoassay (Platelia® Aspergillus) for the detection of Aspergillus antigen in serum

Invasive aspergillosis is a serious problem for immunocompromised patients, especially if neutropenic. The diagnosis of this infection is complicated, since clinical symptoms are often similar to those of other fungal diseases. The chance of detecting the presence of a specific antigen in the serum could confirm the suspected clinical diagnosis and. perhaps, be useful for the follow-up of the patient. The Medical Mycology Committee of the Associazione Microbiologi Clinici Italiani (AMCLI) decided to evaluate in a multicenter prospective study (from I November 1998 to 28 February 1999) the performance of the Platelia Aspergillus Kit (Bio-Rad) for the detection of Aspergillus galactomannan in human serum. The enrolled patients included various groups of immunosuppressed patients (mostly neutropenic). Blood samples were drawn at the time of enrollment. This decision was based upon a clinical diagnosis of probable aspergillosis (antibiotic non-responsive fever for at least 96 hours, cough, hemophthosis and positive chest X-ray). Additional blood samples were drawn on days 3, 6, 9, 12, 15 and 21. Culture and histopathologic examinations were performed according to the individual laboratory workflow. For each patient the laboratory filled a form with all the available clinical information, to create a database on which to evaluate the results of the test. During the study, 187 patients with various kinds of immunosuppression were enrolled. A total of 256 sera were tested: for 117 patients (62.6%) only the basal sample was tested, whereas for the 70 symptomatic patients (37.4%) multiple specimens (range: 1-6) were tested. The results allowed the laboratories to exclude (68.6%) or confirm (31.5%: confirmed and/or probable) the clinical diagnosis of invasive aspergillosis; 4 cases remained undetermined. Based on the results of this study, it seems that the use of this test should be limited to those patients with clinical symptoms of aspergillosis.