Determination of Maduramicin in Feedingstuffs and Premixtures by Liquid Chromatography: Development, Validation, and Interlaboratory Study

A reversed-phase liquid chromatography method for determination of maduramicin in feedingstuffs and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was methanol. Maduramicin was detected at 520 nm after postcolumn derivatization with vanillin.

Liquid Chromatographic Method to Determine Narasin in Feedingstuffs and Premixtures: Development, Validation, and Interlaboratory Study

A reversed-phase liquid chromatography (LC) method for narasin in feedingstuffs and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was methanol–K2HPO4 solution (9 + 1, v/v). Narasin was detected at 600 nm after post-column derivatization with dimethylamino-benzaldehyde. Recovery was >90%. The repeatability (RSDr) in feed (20–140 mg/kg) ranged between 1.2 and 10.5%; the within-laboratory reproducibility (RSDR) ranged between 2.2 and 4.9%. The limit of determination was <20 mg/kg. Other feed additives did not interfere in the assay. The method showed ruggedness against changes in the composition of extraction solvent, eluent, and conditions for post-column reactions. In an interlaboratory study, 5 broiler feeds (4 positive, 1 blank) and 1 premixture were analyzed by 13 laboratories. The RSDr of the feedingstuffs (20–120 mg/kg) varied between 2.17 and 7.57%. The HORRAT ranged between 0.77 and 0.88, with recoveries between 82 and 104%. One laboratory detected small signals in the blank sample, calculated as 0.6 and 2.8 mg/kg. For the premixture, acceptable results for reproducibility could only be obtained after modification of the method: the RSDr was 4.42% and the HORRAT was 1.56 (12 laboratories).

Liquid Chromatographic Method for Nicarbazin in Broiler Feeds and Premixtures: Development, Validation, and Interlaboratory Study

A reversed-phase liquid chromatography method for nicarbazin in broiler feeds and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was an acetonitrile–methanol (1 + 1) mixture. For feedingstuffs, water was also added. The 4,4′-dinitrocarbanilide moiety of nicarbazin was detected at a wavelength of 350 nm. Recovery was ≥ 87%. At 20 mg/kg, the repeatability was 0.7% and the within-laboratory reproducibility was 2.7%. The limit of determination was <20 mg/kg. Other feed additives did not interfere in the assay that proved to be applicable to broiler feeds from different European Union countries. In an interlaboratory study, 4 positive broiler feeds, 1 blank pig feed, and 1 broiler premixture were analyzed by 19 laboratories using the method developed in this study. The relative standard deviation for repeatability (RSDr) of the feedingstuffs (20–240 mg/kg) varied between 2.6 and 10.2%. The HORRAT ranged between 0.70 and 1.22. Recoveries were 91–108%. Three laboratories detected small signals in the blind blank samples, ranging from 0.4 to 2 mg/kg. For the premixture, acceptable results for reproducibility could only be obtained after the sample weight and volume of extraction had been doubled. To avoid excessive dilution of the extracts, the range of the calibration curve had also been doubled. With this modified method, the RSDr was 5.7% and the HORRAT was 1.95 (10 laboratories).

Method of Determination of Appropriate Heat Treatment of Animal Meal by Immunoassay Developed for Detection of Cooked Beef: Interlaboratory Study

An interlaboratory trial was conducted for the validation of an enzyme-linked immunosorbent assay (ELISA) method for determination of appropriate heat treatment of animal meal. A commercially available ELISA test kit developed for the identification of beef in cooked food was used in the study. Twelve laboratories from 7 European countries examined 2 different analytical protocols to establish the most appropriate analytical method. Three different samples were used, 2 animal waste materials sterilized at 129 and 134°C (wet conditions), respectively, and a meat and bone meal material processed at dry conditions (maximum temperature, 140°C). Statistical evaluation applying t-statistics showed that the animal meal treated according to European legislation (>133°C) was clearly distinguishable from the 2 other test materials at a 99% confidence level using both analytical protocols. This method can be considered as a complementary test to the immunoassay developed for the detection of pork in cooked food that is already applied in routine analysis for the surveillance of rendering plants.

Platelet washing to prevent recurrent febrile reactions to leucocyte-reduced transfusions

Symptoms of fever and/or rigours after transfusion continue to occur commonly in patients receiving platelets leucocyte-reduced after storage. A cohort of 24 consecutive patients who had experienced severe or repeated febrile nonhaemolytic reactions to post-storage leucocyte-reduced platelet transfusions were treated with saline-washed, post-storage leucocyte-reduced platelets. The frequency of reactions declined from 20% of transfusions (n = 191) to 0.6% (n = 331) after instituting saline-washed, post-storage leucocyte-reduced platelet transfusions. These results support the hypothesis that substances present in the supernatant of stored platelet concentrates mediate febrile nonhaemolytic transfusion reactions, and provide one strategy for preventing their occurrence.

Blood transfusion and total joint replacement surgery: T helper 2 (TH2) cytokine secretion and clinical outcome

Surgery and blood transfusions have both been reported to cause decreases in various measures of cell-mediated immunity. A study of in vitro T helper lymphocyte type 2 (Th2) cytokine secretion after major joint replacement surgery was performed because these cytokines (IL4 and IL10) generally down-regulate cellular immune function. Th1 cytokines such as IL2 tend to up-regulate cellular immunity. Forty-three patients undergoing elective joint replacement surgery had pre- and multiple post-operative levels of IL2, IL4 and IL10 secretion measured and analysed with regard to demographic and clinical outcome data. Total joint replacement alone without allogeneic transfusions led to substantial increases in peak mean IL4 (2.1 times the pre-operative level) and IL10 secretion in vitro (4.3-fold) compared with much more modest increases in IL2 (1.36-fold) (P < 0.0001 for changes from baseline for each cytokine). In 14 patients who received allogeneic transfusions, these changes were greater than those in recipients of only autologous blood for IL4 (5.0-fold; P = 0.0036 vs. no allogeneic transfusion) and IL10 (15.7-fold; P = 0.079) but not for IL2 (1.38-fold; P = 0.38). The dramatic increase in Th2 cytokine secretion and minimal change in Th1 cytokine secretion after total joint replacement, with or without allogeneic transfusions, was seen regardless of type of anaesthetic, duration of surgery or whether knee or hip replacement occurred. These changes in cytokine patterns may contribute to the decreases in cellular immune function seen after surgery. Allogeneic transfusions but not autologous transfusions appear to exacerbate this immune deviation toward a T helper 2 (Th2) type response, and thus probably contribute to down-regulation of cellular immunity in the setting of joint replacement surgery.

Seedling growth and development on space shuttle

Young pine seedlings, and mung bean and oat seeds were flown on shuttle flights, STS-3 and STS-51F, in March, 1982 and July/August, 1985, respectively. The plant growth units built to support the two experiments functioned mechanically as anticipated and provided the necessary support data. Pine seedlings exposed to the microgravity environment of the space shuttle for 8 days continued to grow at a rate similar to ground controls. Pine stems in flight seedlings, however, averaged 10 to 12% less lignin than controls. Flight mung beans grew slower than control beans and their stems contained about 25% less lignin than control seedlings. Reduced mung bean growth in microgravity was partly due to slower germination rate. Lignin also was reduced in flight oats as compared to controls. Oats and mung beans exhibited upward growing roots which were not observed in control seedlings. Chlorophyll A/B ratios were lower in flight tissues than controls. The sealed PGCs exhibited large variations in atmospheric gas composition but the changes were similar between flight and ground controls. Ethylene was present in low concentrations in all chambers.

Antibodies to plasma proteins: an association with platelet transfusion refractoriness

We hypothesized that antibodies to HLA-linked polymorphic plasma proteins could be involved in platelet refractoriness by an 'innocent bystander' or immune complex mechanism. Employing a kinetic enzyme-linked immunosorbent assay (ELISA) technique the ability of IgG from the plasma of refractory patients to bind to albumin, fibrinogen, complement components C2 and C4 was measured. As compared with controls a high percentage of refractory patients had increased IgG capable of binding to all four plasma proteins: C2 (83%), C4 (83%), albumin (75%), fibrinogen (34%). In the presence of exogenous plasma proteins these antibodies mediated increased deposition of IgG onto normal donor platelets. The plasma protein binding IgG consisted both of monomeric IgG and a broad range of high molecular weight complexes. IgG anti-plasma protein antibody could be eluted from platelets of refractory patients. The development of anti-plasma protein IgG was studied during the course of platelet transfusion therapy and found to increase progressively so that by the 20th transfusion greater than 90% of samples were positive. The presence of plasma protein binding activity correlated with the development of increased levels of platelet bound IgG and refractoriness. Multiple platelet transfusions lead to sensitization to polymorphic determinants on C2 and C4 as well as the formation of high molecular weight complexes. These antibodies and complexes contribute to the deposition of IgG on platelets and may contribute to refractoriness.

A convex hull inclusion test

A new characterization of the interior of the convex hull of a finite point set is given. An inclusion test based on this characterization is, on average, almost linear in the number of points times the dimensionality.

Detection of IgG anti-Lewis (a) antibodies in cord sera by kinetic Elisa

Lewis blood group antibodies rarely, if ever, cause hemolytic disease of the newborn. This observation has been attributed to the absence both of Lewis antigens on fetal cells and of maternal IgG Lewis antibody. In the present study, sera from 13 mother-infant pairs were tested for the presence of anti-Lewis (a) by hemagglutination and by a sensitive and specific kinetic enzyme-linked immunosorbent assay. By routine hemagglutination methods, anti-Lea was present in all maternal samples but absent in all cord samples. By kinetic enzyme-linked immunosorbent assay, IgG anti-Lea was present in 13 of 13 maternal samples and in 12 of 13 cord samples. These results indicate that IgG anti-Lea antibodies are common and do cross the placenta. This suggests that they do not cause hemolytic disease of the newborn because of the low levels of Lewis antigens on fetal red cells.

Cluster definition by the optimization of simple measures

We adopt the following measures of clustering based on simple edge counts in an undirected loop-free graph. Let S be a subset of the points of the graph. The compactness of S is measured by the number of edges connecting points in S to other points in S. The isolation or separation of S is measured by the negative of the number of edges connecting points in S to points not in S. The subset S is a cluster if it is compact and isolated. We study the cluster search problem: find a subset S which maximizes a linear combination of the compactness and (negative) isolation edge counts. We show that a closely related decision problem is NP-complete. We develop a pruned search tree algorithm which is much faster than complete search, especially for graphs which are derived from points embedded in a space of low dimensionality.

Correlation of humoral immunity to Lewis blood group antigens with renal transplant rejection

Recent studies suggest that the Lewis blood group antigens are important for human renal transplantation. A possible mechanism by which Lewis blood group incompatibility could influence allograft rejection was investigated by measuring Lewis antibodies in sera from renal transplant recipients and appropriate controls using conventional hemagglutination and a sensitive and specific kinetic enzyme-linked immunosorbent assay (k-ELISA). The two methods yielded identical results with 14 positive control sera known to contain Lewis antibodies and with 43 sera from negative controls. Antibody was not detected in 16 Lewis-positive transplant patients. However, antibody was detected by k-ELISA in 4/11 Lewis-negative transplant candidates and in 8/8 Lewis-negative recipients of Lewis-incompatible grafts. All 8 grafts were rejected. The one Lewis-negative recipient of a Lewis-negative graft did not develop Lewis antibody nor reject his graft. Of the 12 renal patients in whom antibody was detected by k-ELISA, in only 4 was antibody also demonstrable by hemagglutination. These results indicate that hemagglutination may not be sensitive enough for antibody detection and that Lewis antibodies may play a role in renal allograft rejection.

A new technique in quantitative immunohematology: solid-phase kinetic enzyme-linked immunosorbent assay

A solid-phase kinetic enzyme-linked immunosorbent assay has been developed to measure binding of antibodies to purified or synthetic blood group antigens and tested in the Lewis blood group system. Chemically synthesized Lewis a antigen is used as the target for the binding of serum antibody in this sandwich-type assay. Kinetic, rather than endpoint, determinations are used to calculate the amount of specific antibody. Data are presented showing the assay to be quantitative, sensitive, and specific. It can separately quantitate the amount of IgG or IgM anti-Lewis a present in patient sera. The assay uses commercially available reagents and is semiautomated. Thus, it will be useful for studies in quantitative immunohematology as other blood group antigens become available in purified form.