Essential role for caspase 8 in T-cell homeostasis and T-cell-mediated immunity

Defects in death receptor-mediated apoptosis have been linked to cancer and autoimmune disease in humans. The in vivo role of caspase 8, a component of this pathway, has eluded analysis in postnatal tissues because of the lack of an appropriate animal model. Targeted disruption of caspase 8 is lethal in utero. We generated mice with a targeted caspase 8 mutation that is restricted to the T-cell lineage. Despite normal thymocyte development in the absence of caspase 8, we observed a marked decrease in the number of peripheral T-cells and impaired T-cell response ex vivo to activation stimuli. caspase 8 ablation protected thymocytes and activated T-cells from CD95 ligand but not anti-CD3-induced apoptosis, or apoptosis activated by agents that are known to act through the mitochondria. caspase 8 mutant mice were unable to mount an immune response to viral infection, indicating that caspase 8 deletion in T-cells leads to immunodeficiency. These findings identify an essential, cell-stage-specific role for caspase 8 in T-cell homeostasis and T-cell-mediated immunity. This is consistent with the recent identification of caspase 8 mutations in human immunodeficiency.     

Increased rates of chromosome breakage in BRCA1 carriers are normalized by oral selenium supplementation.

Women who are born with constitutional heterozygous mutations of the BRCA1 gene face greatly increased risks of breast and ovarian cancer. The product of the BRCA1 gene is involved in the repair of double-stranded DNA breaks and it is believed that increased susceptibility to DNA breakage contributes to the cancer phenotype. It is hoped therefore that preventive strategies designed to reduce chromosome damage will also reduce the rate of cancer in these women. To test for increased mutagenicity of cells from BRCA1 carriers, the frequency of chromosome breaks was measured in cultured blood lymphocytes following in vitro exposure to bleomycin in female BRCA1 carriers and was compared with noncarrier relatives. The frequency of chromosome breaks was also measured in BRCA1 carriers following oral selenium supplementation. Carriers of BRCA1 mutations showed significantly greater mean frequencies of induced chromosome breaks per cell than did healthy noncarrier relatives (0.58 versus 0.39; P < 10(-4)). The frequency of chromosome breaks was greatly reduced following 1 to 3 months of oral selenium supplementation (mean, 0.63 breaks per cell versus 0.40; P < 10(-10)). The mean level of chromosome breaks in carriers following supplementation was similar to that of the noncarrier controls (0.40 versus 0.39). Oral selenium is a good candidate for chemoprevention in women who carry a mutation in the BRCA1 gene.     

Inhibition of cell cycle and induction of apoptosis by 2‐oxoheksyl isothiocyanate and alyssin in cell lines carrying various inherited BRCA1 mutations

An important aspect of the chemopreventive activity of isothiocyanates (ITC) is their ability to induce cell growth inhibition and apoptosis. In this study, the effect of two sulforaphane analogues, 2‐oxoheksyl isothiocyanate and alyssin, on lymphoblastoid cells, derived from people carrying four different germ‐line mutations in BRCA1 gene, was tested and compared to the effect on wild type cells. The mutations studied were: C61G; 3819del5; 4153delA, and 5382INSC. Changes in cell viability and density after 2‐oxoheksyl isothiocyanate and alyssin treatment were evaluated, as well as cell cycle progression, mitochondrial membrane potential changes, and phosphatidylserine externalization. Both isothiocyanates were shown to reduce cell viability and density in all cell lines tested, as well as the change in cell cycle phase's distribution. The response of cells to two ITC tested was various, as well as mutation type‐modulated. We found that change of cellular maintenance by chemopreventive agents can be modulated by single allele BRCA1 mutation. Drug Dev. Res. 65:84–92, 2005. © 2005 Wiley‐Liss, Inc.     

The toxicity of cationic surfactants in four bioassays

The purpose of this study was to investigate the toxicity of 15 quaternary ammonium compounds (QACs) in a battery of four bioassays comprising the bacterium Vibrio fischeri, two ciliated protozoa Spirostomum ambiguum and Tetrahymena thermophia, and the anostracean crustacean Artemia franciscana. The compounds were prepared by Professor Pernak's group at Poznań University of Technology (Poland). The toxicity of the test compounds was very high, with EC(LC)(50) values varying from 0.11 to 70 micromol/L. Microtox was the most sensitive bioassay, while the crustacean test was the least sensitive. Among the protozoa T. thermophila was 5-30 times less sensitive than S. ambiguum. The toxicity of the QACs depended on their structure, but no simple correlation was found for all the bioassays applied.     

Wound ballistic evaluation of the TASER® XREP ammunition

The Taser® eXtended Range Electronic Projectile (XREP®) is a wireless conducted electrical weapon (CEW) designed to incapacitate a person from a larger distance. The aim of this study was to analyze the ballistic injury potential of the XREP. Twenty rounds were fired from the Taser®X12 TM shotgun into ballistic soap covered with artificial skin and clothing at different shooting distances (1–25 m). One shot was fired at pig skin at a shooting distance of 10 m. The average projectile velocity was 67.0 m/s. The kinetic energy levels on impact varied from 28–52 J. Depending on the intermediate target, the projectiles penetrated up to 4.2 cm into the ballistic soap. On impact the nose assembly did not separate from the chassis, and no electrical activation was registered. Upon impact, a skin penetration of the XREP cannot be excluded. However, it is very unlikely at shooting distances of 10 m or more. Clothing and a high elasticity limit of the target body area can significantly reduce the penetration risk on impact.     

Can a threshold for 11‐nor‐9‐carboxy‐Δ9 ‐tetrahydrocannabinol in hair be derived when its respective concentration in blood serum indicates regular use?

A 100 μg/L or higher concentration of 11‐nor‐9‐carboxy‐Δ9‐tetrahydrocannabinol (THC‐COOH) in blood serum is generally assumed to be associated with regular and/or heavy use of cannabis. At present, determination of the extent of cannabis use by means of the concentration of THC‐COOH in hair has not been assessed. Therefore, we aimed at establishing a threshold for THC‐COOH concentrations in hair to prove frequent consumption by comparing THC‐COOH concentrations in 129 corresponding serum and hair samples, respectively. The concentration of THC‐COOH in the serum was analyzed by gas chromatography–mass spectrometry and in the hair by liquid chromatography–tandem mass spectrometry. Data were statistically evaluated using receiver operating characteristic curves and contingency tables. Our results suggest that a THC‐COOH concentration of ≥4.2 pg/mg in hair was always accompanied by a THC‐COOH concentration of at least 100 μg/L in blood serum. Should this be confirmed by further studies of a larger study population, a hair concentration of 4.2 pg/mg THC‐COOH can be set as a threshold to predict regular and/or heavy consumption of cannabis even if no corresponding blood sample is available for analysis.     

Environmental monitoring and control strategy of urban mosquito Culicidae (Diptera: Culicidae) populations in Wrocław

Among dipterans of medical and veterinary importance, the mosquitoes (Culicidae) play the most important role both as vectors and nuisance insects. Mass occurrence of floodwater mosquito species in the flooded area in Wroc?aw district (Lower Silesia, Poland) in 1997 has enhanced the already existed problem of mosquito control. A successful model of control strategy for the city based on the currently recommended integrated methodologies with special emphasis on preventive treatment of aquatic larvae with microbial insecticides has been conducted. Bacillus thuringiensis israelensis-based formulations replaced chemicals to control Culex pipiens and Culiseta annulata--two dominant species out of eight noticed during field study in Wroc?aw area in the years 1998-2000. Use of Bti larvicide or other biocontrol agent, conserving biodiversity, requires collecting entomological data, mapping and treating all breeding sources as well as the designing appropriate strategies every year.     

Immune reconstitution after haematopoietic cell transplantation in children: immunophenotype analysis with regard to factors affecting the speed of recovery

Immune reconstitution was studied prospectively in 66 children who underwent 77 haematopoietic cell transplantations (HCT): 46 autologous HCTs in 39 patients and 31 allogeneic HCTs in 27 patients. We studied the dynamic analysis of immune recovery with regard to potential factors affecting its speed, including age, type of HCT, diagnosis, graft-versus-host disease (GvHD) and cytomegalovirus (CMV) infection reactivation. Absolute counts of different lymphocyte subsets and immunoglobulin serum levels were determined in peripheral blood of patients on d -7 and +16, and then at various intervals up to 24 months post transplant. Common patterns of immune recovery after both allogeneic and autologous HCT were identified: (i) CD4+CD45RO+ peripheral T-cell expansion on d +16; (ii) inverted CD4+:CD8+ ratio from d +30 onwards; (iii) rapid natural killer (NK) cell (CD16+/-CD56+) count normalization. We observed prolonged T-cell lymphopenia (CD3+, CD3+CD4+, CD4+CD45RA+) until 24 months after autologous HCT, whereas in the allogeneic setting CD3+CD4+ cells, including naive CD45RA+ cells, returned to normal values at 9 months post transplant. Age > 10 years and coexistence of GvHD and CMV reactivation were associated with a substantial delay in T- (CD4+, including CD45RA+) and B-cell recovery after allogeneic HCT. Multidrug GvHD prophylaxis resulted in impaired T- (CD4+, CD4+CD45RA+) and B-cell reconstitution only in the early phase after allogeneic HCT (up to 4 months). Our results demonstrated that T-cell recovery was severely impaired in children after autologous HCT. It should be emphasized that specific approaches to enhance immune reconstitution are necessary to control minimal residual disease and avoid the risk of infectious complications in the autologous setting. Thymic involution after allogeneic HCT seems to be associated with age and coexistence of GvHD and CMV reactivation.