Analysis of cytotoxic effector cell function in patients with leukemia or aplastic anemia before and after marrow transplantation

Cytotoxic effector cells mediating natural killing (NK), antibody-dependent cellular cytotoxicity (ADCC), and lectin-dependent cellular cytotoxicity (LDCC) were studied in patients with leukemia or aplastic anemia before and/or after marrow transplantation. Before transplantation, about one-third to one-half of the patients were deficient in cytotoxic activity. In patients with leukemia, this was most likely due to large numbers of circulating blast cells diluting or replacing the effector cells. In patients with aplastic anemia there was an apparent absence of the effector cells in a proportion of the patients. After marrow transplantation, cytotoxic activity in all three systems returned to normal rapidly, by 30 days, and remained so through 100 days. However, about 20% of patients studied beyond 1 year were deficient in these functions. There were no significant associations between cytotoxic activity and important clinical parameters including infections, graft-vs-host disease, and recurrence of leukemia. Our findings do not support an immunosurveillance role for NK against leukemia after marrow transplantation. Furthermore, they point out the need for new in vitro approaches for meaningful monitoring of marrow transplant patients. Finally, our results showed a significant discordance between NK, ADCC, and LDCC activities in these immunologically perturbed individuals, indicating that either different cell populations or different cellular mechanisms are involved in these cytotoxic functions.     

Distribution of Acidic- and Neutral Peptidases in Germinating Barley

Activities of barley peptide hydrolases A (acidic peptidase) and H (neutral peptidase) were examined in the growing embryo and in the embryoless tissues of Himalaya barley incubated for 70 hours. Tissues examined were roots, shoots, embryo residue (scutellum + seutellar node + coleorhiza) and the embryoless portion of the kernel. Activity of the hydrolase A increased mainly in the embryo residue during 0 to 30 hours but little thereafter. Activity of hydrolase B increased mainly in the embryo residue but did so linearly over the 70 hour period. A small linear increase occurrence in the embryoless portion during this lime.     

Haemostatic Changes during Dialysis Associated with Thrombus Formation on Dialysis Membranes

Platelet counts, coagulation factors, and the fibrinolytic system were studied in seven regular dialysis patients during the course of haemodialysis by parallel flow (Gambro-Alwall) and coil (Travenol Ultra-Flo 100) dialysers. Significant falls in the patients'' platelet counts and rises in their factor V levels were found with both dialysis systems. The changes were more pronounced over the course of a Gambro-Alwall dialysis, when significant falls in the partial thromboplastin clotting time and in the plasminogen levels were also noted. These haemostatic changes were associated with the retention of platelets on the dialysis membranes and, in the case of the Gambro-Alwall dialyser, with the formation of platelet-fibrin thrombus. This thrombus formation may take place in spite of efficient heparin anticoagulation and may cause excessive blood loss to the regular dialysis patient.     

On the use of historical control data to estimate dose response trends in quantal bioassay.

New tests for trend in proportions, in the presence of historical control data, are proposed. One such test is a simple score statistic based on a binomial likelihood for the "current" study and beta-binomial likelihoods for each historical control series. A closely related trend statistic based on estimating equations is also proposed. Trend statistics that allow overdispersed proportions in the current study are also developed, including a version of Tarone's (1982, Biometrics 38, 215-220) test that acknowledges sampling variation in the beta distribution parameters, and a trend statistic based on estimating equations. Each such trend test is evaluated with respect to size and power under both binomial and beta-binomial sampling conditions for the current study, and illustrations are provided.     

Nuclease digestibility of chromatin is affected by nuclei isolation procedures

Experiments using nucleases as probes of chromatin structure take place in two stages: (1) nuclei isolation, and (2) nuclease digestion. The parameters of the nuclease digestion stage are usually strictly controlled because of nuclease sensitivity to them. However, there have been no reports on whether parameters in the nuclei isolation stage affect the subsequent nuclease digestions. We have evaluated a typical nuclei isolation technique with respect to how changes in the isolation parameters affect nuclease digestion kinetics. Our observations point out that various parameters encountered in the nuclei isolation stage have a significant effect on the subsequent nuclease digestion kinetics of DNAase I. These parameters include the concentration of cells, divalent cations and phosphatase inhibitors. The pH, concentration of NaCl and concentration of detergent had little effect. Micrococcal nuclease was relatively unaffected by changes in the nuclei isolation parameters. The importance of this report lies in the demonstration that lack of control of seemingly insignificant parameters, such as cell concentration during the nuclei isolation stage, leads to subsequent irreproducible results in the DNAase I digestion. These findings indicate that great care must be exercised in the nuclei isolation stage if reproducible work is to be performed with DNAase I.