Bacterial contamination rates following processing of bone marrow and peripheral blood progenitor cell preparations

BACKGROUND: The performance of cultures to assess possible bacterial contamination of bone marrow and peripheral blood progenitor cell preparations is required by the standards of the American Association of Blood Banks. STUDY DESIGN AND METHODS: Consecutive (n = 893) bone marrow and peripheral blood progenitor cell preparations were cultured for assessment of possible contamination by microorganisms. RESULTS: Consecutive bone marrow and peripheral blood progenitor cell preparations (n = 893) were cultured; the overall positive rate detected was 2.5 percent (22/893). The isolates predominantly were skin contaminants (gram-positive cocci) and so-called water-borne organisms (gram-negative rods). The 6.0-percent rate of positivity in 317 bone marrow preparations was higher than the 0.5-percent rate in 576 peripheral blood progenitor cell preparations (p < 10(-6)). Culture- positive preparations were transfused to 16 patients at this institution; however, none of these transfusions led to documented sepsis with the contaminating organism. CONCLUSION: The culture method described here complies with the standards of the American Association of Blood Banks. Contamination can be detected in both bone marrow and peripheral blood progenitor cell preparations. When contaminated preparations are transfused, there are few complications that can be attributed to the contamination.     

Development and validation of a short-term clinical model for assessing calculus inhibitory agents

The purpose of this project was to develop and validate an efficient, short-term clinical model for assessing topically-applied anticalculus agents. In this model, calculus development occurred within 14 days on both labial and lingual surfaces of the mandibular anterior teeth. Because of documented long-term clinical efficacy, pyrophosphate dentifrices were used to investigate the validity of the short-term calculus model for evaluating anticalculus agents. This paper provides the results of the final 3 studies conducted during the development of this model. For each study, the design consisted of two 14-day phases, i.e., a control phase and a treatment phase, separated by a 7-day washout phase. At the start of each phase, a prophylaxis was performed on the mandibular anterior teeth to remove all plaque and calculus. At the end of each phase, supragingival calculus formation on the labial and lingual surfaces of these same teeth was measured using the VMI scoring method. Twice a day during the control phase, subjects applied a control dentifrice undiluted to the test teeth with a custom-fitted toothshield and brushed only the exposed teeth with the same dentifrice. For the treatment phase, subjects were randomly assigned to groups balanced on the basis of control-phase calculus scores and then delivered the dentifrices using the toothshield as in the first phase. After 14 days, calculus formation occurred in all groups. However, the pyrophosphate dentifrice groups had significantly less calculus (16-30%) than the control dentifrice group. These studies demonstrated that this methodology permitted rapid formation of dental calculus, and by substantiating with anticalculus systems documented to have activity in long-term human trials, it is concluded that this short-term clinical model is valid for assessing anticalculus agents.     

Blood counts in healthy donors 1 year after the collection of granulocyte-colony-stimulating factor-mobilized progenitor cells and the results of a second mobilization and collection

BACKGROUND : Granulocyte–colony-stimulating factor (G–CSF)-mobilized blood cells are being used for allogeneic transplants, but the long-term effects of G–CSF on healthy individuals are not known. Furthermore, it is not certain how many CD34+ cells can be collected in a second mobilization and collection procedure. STUDY DESIGN AND METHODS : Nineteen people were given 2, 5, 7.5, or 10 μg of G–CSF per kg per day for 5 days, and blood progenitor cells were collected by apheresis on the sixth day; this was done on two occasions separated by at least 12 months. Blood counts obtained before and after each course of G–CSF and the quantity of cells collected were compared. RESULTS : There were no differences in white cell (WBC), platelet, red cell, and WBC differential counts measured before each course of G–CSF, and all the values were in the normal range. In a subset of 12 people who received 7.5 or 10 μg of G–CSF per kg per day for both courses, the numbers of neutrophils, mononuclear cells, and CD34+ cells in the blood after each course were similar (34.1 ± 7.31 × 10⁹/L vs. 36.4 ± 12.3 × 10⁹/L, p = 0.24; 6.59 ± 2.28 × 10⁹/L vs. 5.63 ± 2.11 × 10⁹/L, p = 0.24; and 92.0 ± 55.6 × 10⁶/L vs. 119.2 ± 104.6 × 10⁸/L; p = 0.48, respectively), as were the quantities of mononuclear cells (31.0 ± 8.4 × 10⁹ vs. 31.0 ± 6.1 × 10⁹; p = 0.64) and CD34+ cells (417 ± 353 × 10⁶ vs. 449 ± 286 × 10⁶; p = 0.53) collected in the two apheresis procedures. Furthermore, there was a positive correlation between the quantity of CD34+ cells collected from each of the 12 people per liter of whole blood processed in the two procedures (r² = 0.86, p<0.001). CONCLUSION : One year after the administration of G–CSF to healthy people, their blood counts were normal and unchanged from pretreatment counts. If healthy people donate blood progenitor cells after a second G–CSF course, the quantity of CD34+ cells collected will be similar to that obtained in the first collection.     

Improved power in crossover designs through linear combinations of baselines

In a crossover design in the absence of any carryover effect, including period‐specific baselines as covariates in an analysis of covariance, is known to increase the precision of the estimated treatment effect. The extent of the efficiency gain is a function of the joint covariance structure of the baselines and post‐treatment responses, as well as the metric used to incorporate the baselines into the analysis. Here, we show how the underlying covariance structure can be leveraged to find an optimal linear combination of baselines so as to minimize the theoretical variance of the analysis of covariance‐based estimated treatment effect. Our work is relevant to complete designs with up to four periods, specifically the 2 × 2, 3 × 3, and 4 × 4. Given that the optimal linear combination of baselines is a function of the covariance structure, which in practice is unknown, we propose an adaptive method. Here, the covariance structure is chosen using information criterion to guide the choice of the linear combination of baselines. Evaluation of the proposed approach suggests that the type I error rate is maintained. Moreover, relative to previously published methods, sizeable gains in power are possible with this method. Results from a 2 × 2 trial exploring renal function, and a 3 × 3 trial with heart rate as the outcome, are used to illustrate the methods. Copyright © 2016 John Wiley & Sons, Ltd.     

SB265610 is an allosteric,inverse agonist at the human CXCR2 receptor

Background and purpose:

In several previous studies, the C-X-C chemokine receptor (CXCR)2 antagonist 1-(2-bromo-phenyl)-3-(7-cyano-3H-benzotriazol-4-yl)-urea (SB265610) has been described as binding competitively with the endogenous agonist. This is in contrast to many other chemokine receptor antagonists, where the mechanism of antagonism has been described as allosteric.

Experimental approach:

To determine whether it displays a unique mechanism among the chemokine receptor antagonists, the mode of action of SB265610 was investigated at the CXCR2 receptor using radioligand and [³⁵S]-GTPγS binding approaches in addition to chemotaxis of human neutrophils.

Key results:

In equilibrium saturation binding studies, SB265610 depressed the maximal binding of [¹²⁵I]-interleukin-8 ([¹²⁵I]-IL-8) without affecting the K_d. In contrast, IL-8 was unable to prevent binding of [³H]-SB265610. Kinetic binding experiments demonstrated that this was not an artefact of irreversible or slowly reversible binding. In functional experiments, SB265610 caused a rightward shift of the concentration-response curves to IL-8 and growth-related oncogene α, but also a reduction in maximal response elicited by each agonist. Fitting these data to an operational allosteric ternary complex model suggested that, once bound, SB265610 completely blocks receptor activation. SB265610 also inhibited basal [³⁵S]-GTPγS binding in this preparation.

Conclusions and implications:

Taken together, these data suggest that SB265610 behaves as an allosteric inverse agonist at the CXCR2 receptor, binding at a region distinct from the agonist binding site to prevent receptor activation, possibly by interfering with G protein coupling.