Effect of background interference on accelerant detection by canines.

Additional studies were performed with respect to examining the lower limits at which canines can reliably detect products commonly used as accelerants and distinguish them from pyrolysis products or background hydrocarbons. As part of a testing exercise performed in conjunction with a national conference of the Canine Accelerant Detection Association (CADA), 34 canines were subjected to a series of tests, some of them were a recertification proficiency. In one of the tests, the dogs were nearly unanimously successful in locating one can (out of five) containing 50% evaporated gasoline at the 5 microL level on a burnt carpet matrix, and pinpointing the 6-in. square sector on a piece of plain carpeting where the same amount of gasoline (5 microL) was applied. However, only half were able to detect a second doped sample containing a lesser amount (0.05, 0.1, or 0.2 microL) of gasoline, and registered a number of alerts on samples containing only burnt carpeting material. The dogs were also tested on measured amounts (2 or 5 microL) of a variety of other light, medium, and heavy petroleum products applied to a variety of substances containing significant pyrolysis products. As a group, the canines were much less successful in pinpointing these products than they were with gasoline at this same level, and again registered a number of alerts on cans containing only pyrolysis products. The significant number of alerts by canines on samples not containing gasoline or other products points out the importance of obtaining laboratory confirmation on samples on which dogs alert, and on keeping accurate field and training records of canines to establish their credibility.

Evaluation of canines for accelerant detection at fire scenes.

In recent years, canines have been successfully used in fire investigations to detect accelerant residues. We set out to determine the lower limits at which canines could reliably detect potential accelerants. Measured amounts ranging from 10 to as little as 0.01 microL of gasoline, kerosene, and isopars were applied to preselected spots along a continuous sample path (25 to 40 feet long) made out of burned and unburned wood or nylon carpeting strips at the testing site. Two canines were led past this sample path at least three times and positive alerts and negative responses were recorded. Both dogs were generally able to alert on spots containing 0.01 microL or more of all three accelerants, at or beyond the purge and trap recovery and gas chromatographic detection method employed. The canines did alert occasionally on background, especially that containing traces of styrene residues, either purposely added in specific amounts or formed upon partial pyrolysis of carpeting material. The dogs alerted on sites containing 0.1 to 1.0 microL of freshly applied gasoline or kerosene placed at actual heavily damaged fire scenes, but were less successful on samples containing smaller amounts.

Regeneration of autotransplanted splenic tissue at different implantation sites.

Inbred animals (Lewis rats) were used to investigate the regeneration of autologously implanted splenic tissue at intra-omental and subcutaneous sites. Quantitative immunohistology with monoclonal antibodies against lymphocytes and macrophages was performed to analyse the cell density of red pulp (RP), periarteriolar lymphoid sheath (PALS), marginal zone (MZ) and follicle, 7-180 days after transplantation. Antigenic, allogeneic and mitogenic stimulation and Northern blotting were also performed. Transplant groups differed from spleen only in the reduced size of PALS; however, quantitative analysis demonstrated subtle differences between spleen and transplants. The cell density of B-cells and ED-1+ macrophages was reduced in the RP, Tsupp/cyt-cells were decreased and B-cells increased in PALS, and B-cells and Thelper-cells reduced in the MZ. No differences could be detected between the transplant groups. Flow-cytometric analysis of cell suspensions from spleen and transplants revealed a reduction of T-cells (OX-19+), MHC-I and transferrin-receptor-bearing cells in both transplant groups, and a decrease in the number of Thelper-cells and ED-3+ macrophages in subcutaneous transplants. Both transplant groups were defective regarding the allogeneic and pokeweed mitogen response. Aberration of the lipopolysaccharide response was restricted to subcutaneous transplants, which additionally showed abnormal expression of interferon-gamma, interleukin-5 and interleukin-6 mRNA. Thus, subtle alterations of the newly developed microenvironment and/or lymphocyte-homing may influence the regeneration of splenic tissue; the implantation site may represent an important parameter in functional reorganisation.

Immunoarchitecture and specific functions of splenic autotransplants at different implantation sites.

The present study deals with the morphological and functional development of intraomentally and subcutaneously implanted splenic tissue. Spleens and splenic transplants from 138 Lewis rats were investigated with immunohistological, immunological and molecular biological methods at different times after operation (up to 200 days postoperatively). The analysis of the development revealed a nonsignificant reduction concerning the weight of subcutaneous replants and a nonsignificant decrease of the weight of female transplants of both groups at different phases after operation. The cell composition of cell suspensions from spleen and both transplant types showed a deficiency of T, B, MHC-I+ cells and a certain macrophage subset (ED-3+ cells) in transplants. In a quantitative immunohistological analysis of compartments (red pulp, periarteriolar lymphoid sheaths, marginal zone and follicles) the T cell reduction was related to the Tsupp/cyt cells and T cell receptor bearing cells in the periarteriolar lymphoid sheaths, whereas the density of T helper cells was normal. In addition, a different homing of kappa-light chain positive and leukocyte common antigen (B cell type)-positive B cells in follicles and marginal zone was detected. The amount of two macrophage subsets (ED-1+ and ED-2+ cells) was increased in the red pulp. Only minor differences in the immunoarchitecture of transplants at different implantation sites were measured. A functional analysis of spleen compared to both transplant groups elicited a B cell defect after LPS stimulation in subcutaneous transplants and a reduced allogeneic response of both transplant types but a normal proliferation of T cells after ConA stimulation and a correct IgM antibody response against sheep red blood cells. The in vivo mRNA expression and the expression kinetics of interferon-gamma and granulocyte-macrophage colony-stimulating factor after antigen stimulation differed in both transplant groups with a remarkable permanent expression of both mediators in subcutaneous transplants. It can be summarized that the results clearly indicate a development of spleen-like immunoarchitecture of intraomental replants with subtle cellular, functional and molecular alterations. In contrast, despite a comparable development, some severe functional defects occurred in subcutaneous implants pointing out the important role of interactions between the regenerating splenic tissue and the target tissue on a functional and molecular level.