Blood graft cellular composition and posttransplant recovery in non-Hodgkin's lymphoma patients mobilized with or without plerixafor: a prospective comparison.

BACKGROUND: Autologous stem cell transplantation is commonly used to treat non-Hodgkin's lymphomas (NHLs). Cellular composition of the blood grafts apparently has a role in the posttransplant hematologic and immune recovery. Plerixafor increases the mobilization of CD34+ cells and higher amounts of various lymphocyte subsets have been reported in the grafts. Limited prospective data are available in regard to graft cellular composition, hematologic and immune recovery, and patient outcomes in NHL patients who receive plerixafor added to chemomobilization. STUDY DESIGN AND METHODS: Forty-one patients with NHL participated in this prospective study. All patients received chemomobilization and 15 poor mobilizers also received plerixafor. CD34+ cell subsets and lymphocyte subsets of cell grafts, posttransplant hematologic and immune recovery, and outcome were evaluated. RESULTS: Blood grafts in the plerixafor group contained a significantly higher proportion of CD34+133+CD38- cells and more lymphocytes of all major subsets except B lymphocytes. Neutrophil engraftment was comparable and platelet recovery slightly slower in the plerixafor group. Natural killer cell recovery was significantly faster in patients mobilized with plerixafor. Otherwise hematologic and immune recovery as well as short-time outcome were comparable even though there was a trend for progression-free survival and overall survival benefit in the plerixafor group. CONCLUSIONS: In poorly mobilizing NHL patients, plerixafor added to chemomobilization is safe and effective. It also modifies the blood graft composition in many ways, some of which have been linked to better outcomes in previous studies. Larger sets of patients and longer follow-up are needed to see whether plerixafor-mobilized grafts are associated with superior outcome of the patients.

Engraftment and outcome after autologous stem cell transplantation in plerixafor-mobilized non-Hodgkin's lymphoma patients.

BACKGROUND: Plerixafor is used in combination with granulocyte-colony-stimulating factor to enhance the mobilization of hematopoietic stem cells. Limited data are available in regard to effects of plerixafor on posttransplant outcomes in chemomobilized patients who appear to mobilize poorly. STUDY DESIGN AND METHODS: Eighty-nine chemomobilized patients with non-Hodgkin's lymphoma (NHL) were included in this retrospective study. Thirty-three patients had received plerixafor preemptively (plerixafor group) and 56 patients served as controls. Posttransplantation outcomes including infections, hematologic recovery, and relapse were recorded. RESULTS: The median fold increase of CD34+ cells after the first plerixafor dose was 4.1 in patients mobilized with chemotherapy plus filgrastim and 7.2 in those mobilized with chemotherapy plus pegfilgrastim (p = 0.027). The median number of collected CD34+ cells was 3.5 × 10(6) CD34+ cells/kg in the plerixafor group and 4.2 × 10(6) CD34+ cells/kg in the control group (p = 0.076). Early engraftment was comparable between the groups (10 days for neutrophils >0.5 × 10(9) /L and 14 days for platelets >20 × 10(9) /L, respectively). Also late engraftment within 12 months was comparable except higher hemoglobin level at 3 months in the control group (121 g/L vs. 112 g/L, p = 0.009). Progression-free survival at 1 year after autologous stem cell transplantation (ASCT) was 79% in the plerixafor group and 86% in the control group (p = 0.399). CONCLUSIONS: Long-term engraftment and outcome after ASCT seem to be comparable in NHL patients receiving plerixafor compared to chemomobilized patients. These observations support the use of plerixafor in patients who mobilize poorly.

Model systems in ecology: dissecting the endophyte-grass literature.

Model systems can facilitate and focus research efforts but ill-chosen or inapt ones can distract or impede scientific progress. In this Opinion article, we pose the question: how can the literature provide appropriate general conclusions if the model systems upon which the literature is based are unrepresentative of the relevant biological diversity? A good example of this problem is the endophyte-grass symbiosis, which is considered to be a classic example of mutualistic interactions. Meta-analysis of the primary literature demonstrates that the conceptual framework for endophyte-grass interactions has largely been based on endophyte-plant-herbivore studies of two agricultural grass species, tall fescue and perennial ryegrass. Consistent with conventional wisdom, the meta-analysis indicates that endophytes slightly increase grass resistance to herbivores. By contrast, endophytes appear not to affect plant performance or competitive ability. The positive effects of endophytes appear to be dependent on genetic variation in the host and endophyte, and on nutrient availability in soils. Thus, the agronomic grass model systems fail to capture the breadth of variability inherent in wild grass-endophyte populations and communities.

Migration behaviour and separation of tramadol metabolites and diastereomeric separation of tramadol glucuronides by capillary electrophoresis.

Capillary electrophoresis with UV detection was used to separate tramadol (TR), a centrally acting analgesic, and its five phase I (M1, M2, M3, M4, M5) and three phase II metabolites (glucuronides of M1, M4 and M5). Several factors were evaluated in optimisation of the separation: pH and composition of the background electrolyte and the influence of a micellar modifier, sodium dodecyl sulfate. Baseline separation of TR and all the analytes was obtained with use of 65 mM tetraborate electrolyte solution at pH 10.65. The lowest concentrations of the analytes that could be detected were below 1 microM for the O-methylated, below 2 microM for the phenolic and ca. 7 microM for the glucuronide metabolites. The suitability of the method for screening of real samples was tested with an authentic urine sample collected after a single oral dose (50 mg) of TR. After purification and five-fold concentration of the sample (solid-phase extraction with Oasis MCX cartridges), the parent drug TR and its metabolites M1, M1G, M5 and M5G were easily detected, in comparison with standards, in an interference-free area of the electropherogram. Diastereomeric separation of TR glucuronides in in vitro samples was achieved with 10 mM ammonium acetate-100 mM formic acid electrolyte solution at pH 2.75 and with basic micellar 25 mM tetraborate-70 mM SDS electrolyte solution at pH 10.45. Both separations showed that glucuronidation in vitro produces glucuronide diastereomers in different amounts. The authentic TR urine sample was also analysed by micellar method, but unambiguous identification of the glucuronide diastereomers was not achieved owing to many interferences.

Glucuronidation of racemic O-desmethyltramadol, the active metabolite of tramadol.

O-Desmethyltramadol, the active metabolite of analgesic tramadol, is metabolised through glucuronidation. The present study was conducted to identify the human UDP-glucuronosyltransferases (UGTs) that catalyse the glucuronidation of O-desmethyltramadol, a racemic mixture of 1R,2R- and 1S,2S-enantiomers. We developed a fast and selective liquid chromatography-mass spectrometry method to separate, analyse and quantify the diastereomeric phenolic O-glucuronides of O-desmethyltramadol. To quantify O-desmethyltramadol glucuronidation, we biosynthesised both phenolic O-glucuronides of O-desmethyltramadol and verified their structure by mass spectrometry and nuclear magnetic resonance spectroscopy. Subsequently, the 16 human UGTs of subfamilies 1A and 2B were screened for O-desmethyltramadol glucuronidation activity. UGTs 1A7-1A10 exhibited a strict stereoselectivity, exclusively glucuroniding the 1R,2R-enantiomer. Similar though not strict enantioselectivity was exhibited by UGT2B15. UGT2B7, on the other hand, glucuronidated both O-desmethyltramadol enantiomers, with slight preference for 1S,2S-O-desmethyltramadol. Enzyme kinetic parameters were determined for the most active UGTs, 1A8 and 2B7. The apparent K(m) or S(50) values were high: 1.2mM±0.23 for 1R,2R-O-desmethyltramadol with UGT1A8 and 1.84±1.2 and 4.6±2.0mM for 1S,2S- and 1R,2R-O-desmethyltramadol enantiomers with UGT2B7, respectively. Glucuronidation analyses of O-desmethyltramadol with human liver microsomes exhibited stereoselectivity, favouring the 1S,2S-O-desmethyltramadol over 1R,2R-O-desmethyltramadol and yielding 62.4 and 24.6pmol/mg/min, respectively. In intestinal microsomes, on the other hand, the two enantiomers were glucuronidated at similar rates, about 6pmol/mg/min. The results shed new light on both tramadol metabolism and the substrate selectivity of the human UGTs.

Consumption of grass endophytes alters the ultraviolet spectrum of vole urine.

Fungal endophytes of grasses are known to benefit their hosts directly by increasing resistance to herbivores through mycotoxins. We propose and test assumptions of a novel hypothesis according to which fungal endophytes of grasses may benefit their hosts also indirectly by increasing the conspicuousness of a mammalian herbivore, the field vole (Microtus agrestis), to its avian predators by enhancing the ultraviolet visibility of vole urine. We found that field voles feeding on endophyte-infected meadow ryegrass (Lolium pratense) lost body mass, while voles feeding on non-infected meadow ryegrass gained mass. More interestingly, the maximum peak intensity of ultraviolet fluorescence in the urine of voles feeding on endophyte-infected grass shifted from over 380 nm to circa 370 nm, which is the suggested maximum sensitivity of the ultraviolet pigments in the eyes of vole-eating raptors. Therefore, grazing on endophyte-infected grass alters the ultraviolet spectrum of vole urine, thus potentially enhancing its visibility to avian predators.

Endophytic fungus decreases plant virus infections in meadow ryegrass (Lolium pratense).

We studied the effects of fungal endophyte infection of meadow ryegrass (Lolium pratense=Festuca pratensis) on the frequency of the barley yellow dwarf virus (BYDV). The virus is transferred by aphids, which may be deterred by endophyte-origin alkaloids within the plant. In our experiment, we released viruliferous aphid vectors on endophyte-infected and endophyte-free plants in a common garden. The number of aphids and the percentage of BYDV infections were lower in endophyte-infected plants compared to endophyte-free plants, indicating that endophyte infection may protect meadow ryegrass from BYDV infections.

Are endophyte-mediated effects on herbivores conditional on soil nutrients?

Neotyphodium endophytes are assumed to have mutualistic relationship with their grass hosts, mainly resulting from mycotoxin production increasing plant resistance to herbivores by the fungus that subsists on the plant. To study importance of often ignored environmental effects on these associations, we performed a greenhouse experiment to examine the significance of endophyte infection and nutrient availability for bird-cherry aphid ( Rhopalosiphum padi) performance on meadow fescue ( Lolium pratense). Naturally endophyte-infected (E+), uninfected (E-), or manipulatively endophyte-free (ME-) half-sib families of meadow fescue were grown on two soil nutrient levels. Endophyte infection reduced aphid performance in general. However, to our knowledge, this is the first study to demonstrate experimentally that herbivore performance decreases on E+ host plants with increasing availability of nutrients in soils. Potential improvement in herbivore performance in high nutrient soils and decreased plant performance in low nutrient soils in ME- plants, compared to E- and E+ plants, suggests that loss of endophyte infection after long coevolutionary relationship may be critical to plant fitness.