Identilication of the novel cycloaliphatic brominated flame retardant 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane in Canadian Arctic beluga (Delphinapterus leucas)

1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) is used primarily as an additive flame retardant. Technical grade TBECH consists of near equimolar amounts of two (of a possible four) diastereoisomers: rac-(1R,2R)-1,2-dibromo-(4S)-4-((1S)-1,2-dibromoethyl)cyclohexane ((alpha-TBECH) and rac-(1R,2R)-1,2-dibromo-(4S)-4-((1R)-1,2-dibromoethyl)cyclohexane (beta-TBECH). The two other possible isomers, gamma- and delta-TBECH, appear in the technical mixture when heated at temperatures above 120 degrees C. Careful selection of GC-capillary column length was critical in resolution of the two main diastereoisomers. Column lengths of 60 or 30 m (0.25 microm film thickness) resulted in incomplete separation of the alpha- and beta-isomers, while on a 10 m column, the isomers were baseline separated. The gamma- and delta-isomers could not be resolved on any column length in this study. Increased injector port temperature induced thermal conversion of the alpha- and beta-isomers to gamma- and delta-TBECH. Electron impact ionization (EI) was used to provide specificity because no characteristic ions in the electron capture negative ionization (ECNI) mass spectrum of TBECH were evident. In EI, the dominant ions in the mass spectrum corresponded to a concomitant loss of HBr and Br from the molecular ion; the biggest peak in this ion cluster (m/z 266.9208) was used for quantitation and the second biggest peak (m/z 264.9227) was used for confirmation. Beluga (Delphinapterus leucas) blubber extracts of animals from the Canadian Arctic (n=29) were analyzed using low resolution (LR) MS and high resolution (HR) MS run at a resolving power of 10,000. beta-TBECH was the only isomer observed in the samples and was detected in 17 samples. The LRMS technique appeared to overestimate beta-TBECH concentrations compared to HRMS, suggesting a small interference arose at the nominal mass monitored. This potential interference also led to some false positive and negative values (n=7) based on the expected ion ratio of the quantitation and confirmation ions. Observed concentrations of the beta-isomer as measured by HRMS ranged from 1.1 to 9.3 ng/g (lipid weight).     

Examination of isomer specific bioaccumulation parameters and potential in vivo hepatic metabolites of syn- and anti-Dechlorane Plus isomers in juvenile rainbow trout (Oncorhynchus mykiss)

Juvenile rainbow trout (Oncorhynchus mykiss) were exposed in the laboratory to elevated doses of syn- and anti-isomers of Dechlorane Plus (DP) via their diet for 49 days (uptake phase), followed by 112 days of untreated food (depuration phase) to examine bioaccumulation parameters and possible metabolic products. Three groups of 60 fish were used in the study. Two groups were exposed separately to food fortified with known concentrations of syn- (0.79 +/- 0.03 microg/g, lipid weight) and anti-DP (1.17 +/- 0.12 microg/g, lipid weight) while a third control group was fed unfortified food. Neither isomer reached steady-state after 49 days of exposure. Only the syn-isomer accumulated linearly in the fish (whole-body minus liver) during the dosing phase with a calculated uptake rate constant of 0.045 +/- 0.005 (arithmetic mean +/- 1 x standard error) nmoles per day. A similar uptake rate was also observed for this isomer in the liver. The elimination of both isomers from the whole fish (minus liver) obeyed first order depuration kinetics (syn-: r2 = 0.6427, p < 0.001, anti-: r2 = 0.5350, p < 0.005) with calculated half-lives (t1/2) of 53.3 +/- 13.1 (syn-) and 30.4 +/- 5.7 (anti-) days. Elimination of the isomers from the liver was difficult to interpret because of suspected enterohepatic circulation and redistribution of the isomers in the liver during clearance from other tissues. The biomagnification factor (BMF, determined in whole fish minus liver) of the syn-isomer (5.2) was greater than the anti-isomer (1.9) suggesting that the former isomer is more bioavailable. A suite of metabolites were screened for in the liver including dechlorinated, hydroxylated, methoxylated and methyl sulfone degradates. Even with the purposely high dose used in the uptake phase, none of these degradates could be detected in the extracts. This suggests that if metabolites of DP are detected in fish from aquatic food webs their presence is likely not from in vivo biotransformation of the parent compound.     

Neutrophilic cell production by combination of stem cell factor and thrombopoietin from CD34(+) cord blood cells in long-term serum-deprived liquid culture

In the present study, we investigated the effects of stem cell factor (SCF) and/or thrombopoietin (TPO) on the cell production by cord blood CD34(+) cells using a serum-deprived liquid culture system. Although SCF alone supported a modest production of neutrophilic cells and a remarkable generation of mast cells, the addition of TPO to the culture containing SCF caused an apparent generation of neutrophilic cells, identified by immunocytochemical staining and flow cytometric analysis. The significant production of neutrophilic cells by SCF and TPO was persistently observed from 2 weeks to 2 to 3 months of culture. The interaction between SCF and TPO on the neutrophilic cell generation was greater than the combined effects of SCF with granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF). The addition of neutralizing antibody against G-CSF or GM-CSF did not influence the SCF + TPO-dependent neutrophilic cell production. A single-cell culture study showed that not only CD34(+)CD38(+) c-kit+ cells but also CD34(+)CD38(-)c-kit+ cells were responsible for the neutrophilic cell generation. In clonal cell cultures, GM progenitors as well as erythroid progenitors and multipotential progenitors expanded in the cultures supplemented with SCF and TPO. The neutrophilic cells grown by SCF + TPO were at myeloblast to band cell stages, and scarcely matured to segmented neutrophils. In addition, the cells generated by SCF + TPO were stained with monoclonal antibodies against myeloperoxidase, elastase, lactoferrin, and CD11b, but they had negligible levels of alkaline phosphatase (ALP) and CD35. The replating of the CD34(-)c-kit-/low CD15(+) cells grown by SCF + TPO into a culture containing SCF + G-CSF permitted both the terminal maturation into segmented cells and the appearance of ALP and CD35. These results indicate the existence of a G-CSF/GM-CSF-independent system of neutrophilic cell production.     

Aspirin in essential thrombocythemia: status quo and quo vadis

Aspirin has a well established role in the prevention of arterial thrombosis. Discussion on the efficacy and safety of aspirin in the treatment and prophylaxis of thrombosis in essential thrombocythemia (ET) has become an important issue. The rationale for its use in ET comes from the observation that arterial thrombosis and platelet-mediated microcirculatory disturbances are the major causes of morbidity and mortality in ET. Experimental data have shown persistently elevated levels of thromboxane A2 (TXA2) in ET patients probably reflecting an enhanced in vivo platelet activation. Increased TXA2 biosynthesis and platelet activation in vivo in ET are selectively suppressed by repeated low doses of aspirin. ET-related symptoms such as erythromelalgia, transient neurologic and ocular disturbances are sensitive to aspirin. However, the benefit of low-dose aspirin is still uncertain in the primary prevention of thrombosis in ET. Furthermore, aspirin may unmask a latent bleeding diathesis frequently present in ET which may result in severe hemorrhagic complications. Thus, aspirin is contraindicated in ET patients with a bleeding history or a very high platelet count (> 1500 x 10(9)/L) leading to the acquisition of von Willebrand factor deficiency. If indicated, aspirin is presently used in the widely accepted low-dose regimen of 100 mg daily. However, an optimal effective dose has not yet been established. To further evaluate the efficacy and safety of aspirin in ET, prospective clinical trials are needed.     

Comparison of alcohol-preferring and nonpreferring selectively bred rat lines. I. Ethanol initiation and limited access operant self-administration

Several lines of alcohol-preferring and alcohol-nonpreferring rats have been developed using selective breeding based on 24-hr homecage ethanol consumption. However, it remains unclear if the selection based on two-bottle choice resulted in similar ethanol self-administration when measured using an operant procedure. In this paper, we compare our previous work using alcohol-accepting (AA) and alcohol-nonaccepting (ANA) rats with data obtained using the identical procedures in the (P) and (NP) rat lines, and both replicate lines of the high alcohol drinking (HAD1 and HAD2) and low alcohol drinking (LAD1 and LAD2) lines. All rats from each line were initiated to self-administer 10% ethanol using the sucrose fading procedure. After initiation, increasing concentrations of ethanol up to 30% ethanol were tested. The results indicated that only in the LAD1 and LAD2 lines was ethanol presentation not able to maintain lever pressing after initiation. Compared with the AA line, the P, HAD1, HAD2, and NP lines all self-administered more ethanol in the operant paradigm after initiation. The ANA line self-administered less ethanol than the AA line, but more than the LAD lines. Correlational analysis of homecage consumption with operant ethanol self-administration suggested that approximately 62% of the genetic variance in operant self-administration resulted from genes selected for the homecage drinking. At the same time, it was clear that there were genetic influences on operant self-administration that were not selected for by homecage ethanol drinking.     

Experimental infection of axenic mice by "Yersinia enterocolitica" (author's transl)

Although most of Yersinia enterocolitica strains isolated from man have no pathogenicity for laboratory animals, it has been demonstrated that some strains are pathogenic for conventional mice and that most of the strains are probably pathogenic for Nude mice. The authors report the results of the infection of germ-free mice with a strain of Y. enterocolitica which is non pathogenic for holoxenic mice. It appears that C3H/He mice are sensitive to the infection by gavage or aerogenic and peritoneal routes. They all die within 8 to 12 days after injection of an inoculum of 5.10(5) viable cells. Germ-free NCS mice were also sensitive to the oral and aerogenic infection but not to the peritoneal infection; the difference between C3H/He and NCS sensitivity to this way of infection could be explained by a higher bactericidal activity of the peritoneal phagocytes of the latter. The C3H/He and NCS holoxenic control mice infected with the same inoculum of the same strain, did not show any symptoms and all attempts to isolate Y. enterocolitica failed three months after the challenge. Germ-free mice killed by the infection showed histopathological findings, i.e. abscesses involving intestinal wall. liver and spleen; they were similar to those described in experiments with pathogenic strains for conventional mice (holoxenic) and to those observed in infection of athymic Nude mice with strains non pathogenic for conventional mice. This infectious disease model is discussed in regards to the natural human infection.     

Effects of 5-hydroxytryptamine and bradykinin in cat dorsal horn neurones activated by noxious stimuli

The levels of homovarillic acid and 3,4-dihydroxyphenylacetic acid in rat c. striatum after acute and 10 day administration of clozapine (30 and 100 mg/kg p.o.), thioridazine (100 mg/kg p.o.), haloperidol (1 mg/kg p.o.), and chlorpromazine (30 mg/kg p.o.), were estimated. With clozapine and haloperidol, the mesolimbic area was also investigated. With all these neuroleptics, the levels of both dopamine metabolites were reduced after a 10 day treatment as compared to acute administration, sometimes almost to control values. With clozapine, however, such a reduction occurred only with the higher dose of 100 mg/kg p.o., acting for a period longer than 24 h. This tolerance phenomenon was also observed with clozapine and haloperidol in the mesolimbic area. We conclude that clozapine is not qualitatively different from classical neuroleptics with respect to development of biochemical tolerance.