Dietary exposure to four sizes of spherical polystyrene, polylactide and silica nanoparticles does not affect mortality, behaviour, feeding and energy assimilation of Gammarus roeseli.

The abundance and persistence of plastic nanoparticles in aquatic habitats are considered a threat to marine and freshwater biota. However, the risk assessment of plastic particles is complicated due to various factors that need to be considered, including composition, size and environmental abundance. This study investigated the behavioural response of a key river species, Gammarus roeseli, to dietary exposure of plain biodegradable and non-biodegradable plastic as well as to natural small micro- and nanoparticles. Mortality, feeding, swimming velocity and energy assimilation endpoints were examined by considering four particles sizes ranging from 30 to 1000 nm in two concentrations. Contrary to our expectations, neither decreasing size nor increasing abundance of each tested particle impacted any of the examined endpoints. Likewise, dietary exposition with biodegradable plain polylactide did not induce other or stronger effects than non-biodegradable plain polystyrene or natural silica micro- and nanoparticles, as all three particle types did not lead to adverse effects on G. roeseli. These findings also suggest that the functional role of Gammarus roeseli as a shredder is not impaired due to particle occurrence within the exposure range of this study.

NWChem: Past, present, and future.

Specialized computational chemistry packages have permanently reshaped the landscape of chemical and materials science by providing tools to support and guide experimental efforts and for the prediction of atomistic and electronic properties. In this regard, electronic structure packages have played a special role by using first-principle-driven methodologies to model complex chemical and materials processes. Over the past few decades, the rapid development of computing technologies and the tremendous increase in computational power have offered a unique chance to study complex transformations using sophisticated and predictive many-body techniques that describe correlated behavior of electrons in molecular and condensed phase systems at different levels of theory. In enabling these simulations, novel parallel algorithms have been able to take advantage of computational resources to address the polynomial scaling of electronic structure methods. In this paper, we briefly review the NWChem computational chemistry suite, including its history, design principles, parallel tools, current capabilities, outreach, and outlook.

Combusting vegetable oils in diesel engines: the impact of unsaturated fatty acids on particle emissions and mutagenic effects of the exhaust.

High particle emissions and strong mutagenic effects were observed after combustion of vegetable oil in diesel engines. This study tested the hypothesis that these results are affected by the amount of unsaturated or polyunsaturated fatty acids of vegetable oils. Four different vegetable oils (coconut oil, CO; linseed oil, LO; palm tree oil, PO; and rapeseed oil, RO) and common diesel fuel (DF) were combusted in a heavy-duty diesel engine. The exhausts were investigated for particle emissions and mutagenic effects in direct comparison with emissions of DF. The engine was operated using the European Stationary Cycle. Particle masses were measured gravimetrically while mutagenicity was determined using the bacterial reverse mutation assay with tester strains TA98 and TA100. Combustion of LO caused the largest amount of total particulate matter (TPM). In comparison with DF, it particularly raised the soluble organic fraction (SOF). RO presented second highest TPM and SOF, followed by CO and PO, which were scarcely above DF. RO revealed the highest number of mutations of the vegetable oils closely followed by LO. PO was less mutagenic, but still induced stronger effects than DF. While TPM and SOF were strongly correlated with the content of polyunsaturated fatty acids in the vegetable oils, mutagenicity had a significant correlation with the amount of total unsaturated fatty acids. This study supports the hypothesis that numbers of double bounds in unsaturated fatty acids of vegetable oils combusted in diesel engines influence the amount of emitted particles and the mutagenicity of the exhaust. Further investigations have to elucidate the causal relationship.

A variant of the CXCL11 gene may influence susceptibility to contact allergy, particularly in polysensitized patients.

BACKGROUND: Hereditary factors may influence individual susceptibility to contact allergy. OBJECTIVES: To investigate genetic variants with impacts on early inflammatory reactions and T cell functions that possibly increase the risk of contact allergy. PATIENTS AND METHODS: Three hundred and seventy two patients undergoing patch testing were recruited from the Information Network of Departments of Dermatology (IVDK). Of these, 133 were monosensitized and 239 were polysensitized, defined as reacting to three or more unrelated sensitizers. Within the polysensitized individuals, a subgroup with at least one particularly strong patch test reaction (strong reactors; n = 194) was considered. Three hundred and forty-seven blood bank donors served as controls. Fifteen genetic variants in 13 genes were analysed. RESULTS: The homozygous variant CXCL11 AA genotype (rs6817952) was significantly more frequent among polysensitized patients (10 of 239 = 4.2%; p = 0.0048; odds ratio 7.49; 95%CI: 1.7-36.1) than among monosensitized patients (2.2%) and in the control group (0.6%). None of the remaining genetic variants investigated were characterized by similarly strong associations. However, the significance was lost after correction for multiple comparisons. CONCLUSIONS: The homozygous variant CXCL11 genotype is associated with an increased risk of contact allergy. To confirm this exploratory finding, further independent studies are needed.

Structural Evolution of GaOx-Shell and Intermetallic Phases in Ga-Pt Supported Catalytically Active Liquid Metal Solutions.

We present a comprehensive scale-bridging characterization approach for supported catalytically active liquid metal solutions (SCALMS) which combines lab-based X-ray microscopy, nano X-ray computed tomography (nano-CT), and correlative analytical transmission electron microscopy. SCALMS catalysts consist of low-melting alloy particles and have demonstrated high catalytic activity, selectivity, and long-term stability in propane dehydrogenation (PDH). We established an identical-location nano-CT workflow which allows us to reveal site-specific changes of Ga-Pt SCALMS before and after PDH. These observations are complemented by analytical transmission electron microscopy investigations providing information on the structure, chemical composition, and phase distribution of individual SCALMS particles. Key findings of this combined microscopic approach include (i) structural evolution of the SCALMS particles' GaOx shell, (ii) Pt segregation toward the oxide shell leading to the formation of Ga-Pt intermetallic phases, and (iii) cracking of the oxide shell accompanied by the release of liquid Ga-Pt toward the porous support.

Combustion of hydrotreated vegetable oil and jatropha methyl ester in a heavy duty engine: emissions and bacterial mutagenicity.

Research on renewable fuels has to assess possible adverse health and ecological risks as well as conflicts with global food supply. This investigation compares the two newly developed biogenic diesel fuels hydrotreated vegetable oil (HVO) and jatropha methyl ester (JME) with fossil diesel fuel (DF) and rapeseed methyl ester (RME) for their emissions and bacterial mutagenic effects. Samples of exhaust constituents were compared after combustion in a Euro III heavy duty diesel engine. Regulated emissions were analyzed as well as particle size and number distributions, carbonyls, polycyclic aromatic hydrocarbons (PAHs), and bacterial mutagenicity of the exhausts. Combustion of RME and JME resulted in lower particulate matter (PM) compared to DF and HVO. Particle numbers were about 1 order of magnitude lower for RME and JME. However, nitrogen oxides (NOX) of RME and JME exceeded the Euro III limit value of 5.0 g/kWh, while HVO combustion produced the smallest amount of NOX. RME produced the lowest emissions of hydrocarbons (HC) and carbon monoxide (CO) followed by JME. Formaldehyde, acetaldehyde, acrolein, and several other carbonyls were found in the emissions of all investigated fuels. PAH emissions and mutagenicity of the exhausts were generally low, with HVO revealing the smallest number of mutations and lowest PAH emissions. Each fuel showed certain advantages or disadvantages. As proven before, both biodiesel fuels produced increased NOX emissions compared to DF. HVO showed significant toxicological advantages over all other fuels. Since jatropha oil is nonedible and grows in arid regions, JME may help to avoid conflicts with the food supply worldwide. Hydrogenated jatropha oil should now be investigated if it combines the benefits of both new fuels.

Transport of lipids from golgi to plasma membrane is defective in tangier disease patients and Abc1-deficient mice.

Mutations in the gene encoding ATP-binding cassette transporter 1 ( ABC1) have been reported in Tangier disease (TD), an autosomal recessive disorder that is characterized by almost complete absence of plasma high-density lipoprotein (HDL), deposition of cholesteryl esters in the reticulo-endothelial system (RES) and aberrant cellular lipid trafficking. We demonstrate here that mice with a targeted inactivation of Abc1 display morphologic abnormalities and perturbations in their lipoprotein metabolism concordant with TD. ABC1 is expressed on the plasma membrane and the Golgi complex, mediates apo-AI associated export of cholesterol and phospholipids from the cell, and is regulated by cholesterol flux. Structural and functional abnormalities in caveolar processing and the trans-Golgi secretory pathway of cells lacking functional ABC1 indicate that lipid export processes involving vesicular budding between the Golgi and the plasma membrane are severely disturbed.

Potential hazards associated with combustion of bio-derived versus petroleum-derived diesel fuel.

Fuels from renewable resources have gained worldwide interest due to limited fossil oil sources and the possible reduction of atmospheric greenhouse gas. One of these fuels is so called biodiesel produced from vegetable oil by transesterification into fatty acid methyl esters (FAME). To get a first insight into changes of health hazards from diesel engine emissions (DEE) by use of biodiesel scientific studies were reviewed which compared the combustion of FAME with common diesel fuel (DF) for legally regulated and non-regulated emissions as well as for toxic effects. A total number of 62 publications on chemical analyses of DEE and 18 toxicological in vitro studies were identified meeting the criteria. In addition, a very small number of human studies and animal experiments were available. In most studies, combustion of biodiesel reduces legally regulated emissions of carbon monoxide, hydrocarbons, and particulate matter. Nitrogen oxides are regularly increased. Among the non-regulated emissions aldehydes are increased, while polycyclic aromatic hydrocarbons are lowered. Most biological in vitro assays show a stronger cytotoxicity of biodiesel exhaust and the animal experiments reveal stronger irritant effects. Both findings are possibly caused by the higher content of nitrogen oxides and aldehydes in biodiesel exhaust. The lower content of PAH is reflected by a weaker mutagenicity compared to DF exhaust. However, recent studies show a very low mutagenicity of DF exhaust as well, probably caused by elimination of sulfur in present DF qualities and the use of new technology diesel engines. Combustion of vegetable oil (VO) in common diesel engines causes a strongly enhanced mutagenicity of the exhaust despite nearly unchanged regulated emissions. The newly developed fuel "hydrotreated vegetable oil" (HVO) seems to be promising. HVO has physical and chemical advantages compared to FAME. Preliminary results show lower regulated and non-regulated emissions and a decreased mutagenicity.

Mutagenicity of diesel engine exhaust is eliminated in the gas phase by an oxidation catalyst but only slightly reduced in the particle phase.

Concerns about adverse health effects of diesel engine emissions prompted strong efforts to minimize this hazard, including exhaust treatment by diesel oxidation catalysts (DOC). The effectiveness of such measures is usually assessed by the analysis of the legally regulated exhaust components. In recent years additional analytical and toxicological tests were included in the test panel with the aim to fill possible analytical gaps, for example, mutagenic potency of polycyclic aromatic hydrocarbons (PAH) and their nitrated derivatives (nPAH). This investigation focuses on the effect of a DOC on health hazards from combustion of four different fuels: rapeseed methyl ester (RME), common mineral diesel fuel (DF), SHELL V-Power Diesel (V-Power), and ARAL Ultimate Diesel containing 5% RME (B5ULT). We applied the European Stationary Cycle (ESC) to a 6.4 L turbo-charged heavy load engine fulfilling the EURO III standard. The engine was operated with and without DOC. Besides regulated emissions we measured particle size and number distributions, determined the soluble and solid fractions of the particles and characterized the bacterial mutagenicity in the gas phase and the particles of the exhaust. The effectiveness of the DOC differed strongly in regard to the different exhaust constituents: Total hydrocarbons were reduced up to 90% and carbon monoxide up to 98%, whereas nitrogen oxides (NO(X)) remained almost unaffected. Total particle mass (TPM) was reduced by 50% with DOC in common petrol diesel fuel and by 30% in the other fuels. This effect was mainly due to a reduction of the soluble organic particle fraction. The DOC caused an increase of the water-soluble fraction in the exhaust of RME, V-Power, and B5ULT, as well as a pronounced increase of nitrate in all exhausts. A high proportion of ultrafine particles (10-30 nm) in RME exhaust could be ascribed to vaporizable particles. Mutagenicity of the exhaust was low compared to previous investigations. The DOC reduced mutagenic effects most effectively in the gas phase. Mutagenicity of particle extracts was less efficiently diminished. No significant differences of mutagenic effects were observed among the tested fuels. In conclusion, the benefits of the DOC concern regulated emissions except NO(X) as well as nonregulated emissions such as the mutagenicity of the exhaust. The reduction of mutagenicity was particularly observed in the condensates of the gas phase. This is probably due to better accessibility of gaseous mutagenic compounds during the passage of the DOC in contrast to the particle-bound mutagens. Concerning the particulate emissions DOC especially decreased ultrafine particles.

[Obscure exophthalmus]. / Unklarer Exophthalmus.

A 63-year-old male patient presented with retrobulbar pressure which had been present for 1 year. Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) revealed symmetrical retrobulbar, perivascular and retroperitoneal infiltration of soft tissue and also showed cardiac involvement. In combination with the histological findings displaying infiltration by foamy histiocytes, Erdheim-Chester disease was diagnosed.

Toxoplasma gondii myosins B/C: one gene, two tails, two localizations, and a role in parasite division.

In apicomplexan parasites, actin-disrupting drugs and the inhibitor of myosin heavy chain ATPase, 2,3-butanedione monoxime, have been shown to interfere with host cell invasion by inhibiting parasite gliding motility. We report here that the actomyosin system of Toxoplasma gondii also contributes to the process of cell division by ensuring accurate budding of daughter cells. T. gondii myosins B and C are encoded by alternatively spliced mRNAs and differ only in their COOH-terminal tails. MyoB and MyoC showed distinct subcellular localizations and dissimilar solubilities, which were conferred by their tails. MyoC is the first marker selectively concentrated at the anterior and posterior polar rings of the inner membrane complex, structures that play a key role in cell shape integrity during daughter cell biogenesis. When transiently expressed, MyoB, MyoC, as well as the common motor domain lacking the tail did not distribute evenly between daughter cells, suggesting some impairment in proper segregation. Stable overexpression of MyoB caused a significant defect in parasite cell division, leading to the formation of extensive residual bodies, a substantial delay in replication, and loss of acute virulence in mice. Altogether, these observations suggest that MyoB/C products play a role in proper daughter cell budding and separation.

Multi-walled carbon nanotubes induce stronger migration of inflammatory cells in vitro than asbestos or granular particles but a similar pattern of inflammatory mediators.

Biopersistent pro-inflammatory fibers are suspected human carcinogens. Cytotoxicity and transcription of pro- and anti-inflammatory mediators of different fibers were investigated in functional relationship to chemotaxis in vitro as a model for fiber-induced inflammation of the lung. We challenged NR8383 rat macrophages with multi-walled carbon nanotubes (MWCNT) and various asbestos fibers. The resulting cell supernatants were than studied using the Particle-induced Cell Migration Assay (PICMA) and cytotoxicity was determined using the LDH test. Expression of inflammatory mediators was analyzed with qPCR and verified by ELISA. Chrysotile A and the rigid, needle-shaped NM-401 caused the strongest cytotoxic effects and the largest number of migrated cells. In contrast, the MWCNT NM-400, NM-402, and NM403 were apparently non-cytotoxic but induced pronounced cell migration showing a very steep dose response. However, the strength of cell migration and cytotoxicity of the asbestos fibers were correlated. The expression profile of inflammatory mediators was comparable, although cytotoxicity of the MWCNT NM-401 and NM-403 differed strongly. Induction of the corresponding proteins was confirmed for CCL2, CCL3, CXCL1, CXCL3, IL1RA (IL1RN), CSF1, GDF15 and TNFa. Chrysotile A and NM-401 induced much stronger chemotaxis than the non-fibrous particles reported in our previous study. Cytotoxic and chemotactic effects correspond to the induction of inflammatory mediators.

Variations of the melanocortin-1 receptor and the glutathione-S transferase T1 and M1 genes in cutaneous malignant melanoma.

Variations in the melanocortin-1 receptor (MC1R) and in the glutathione-S transferase genes mu1 (GSTM1) and theta 1 (GSTT1) have been reported to influence UV sensitivity and melanoma risk. MC1R is one of the major genes that determine skin pigmentation because the melanocortin-1 receptor regulates eumelanin synthesis. GSTT1 and GSTM1 are enzymes expressed in the skin that detoxify products of oxidative stress reactions caused by UV irradiation. In this study variations in the MC1R, GSTM1 and T1 genes were analyzed in 347 healthy subjects and 322 patients with cutaneous malignant melanoma by direct cycle sequencing, RFLP and multiplex PCR. Important phenotypic characteristics of the study participants were obtained to assess whether genetic associations occurred independently of phenotypic risk factors for melanoma. We found an association of the MC1R D84E and R151C polymorphisms with melanoma (odds ratios for carriage of the rare allele 4.96, 95% CI [1.06-23.13], P = 0.032, and 1.69, 95% CI [1.12-2.55], P = 0.013, respectively). Melanoma risk increased with the number of variant MC1R alleles carried by an individual (P = 0.003). In a multivariate model, however, only the D84E polymorphism influenced melanoma risk independently of the risk factors fair skin type, high nevus count and high age (P = 0.047). There was no effect of homozygous GST M1 or T1 deletions on melanoma risk. In contrast to previous data, there was no evidence that GSTM1 deficiency influences melanoma risk in the subgroup of individuals with red or blond hair.

Mutagenicity of cytochrome P450 2E1 substrates in the Ames test with the metabolic competent S. typhimurium strain YG7108pin3ERb5.

UNLABELLED: Poor metabolic competence of in vitro systems was proposed to be one of their major shortcomings accounting for false negative results in genotoxicity testing. For several "low molecular weight cancer suspects" this was specifically attributed to the lack of cytochrome P450 2E1 (CYP2E1) in conventional in vitro metabolising systems. One promising attempt to overcome this problem is the transfection of "methyltransferase-deficient"S. typhimurium strains with the plasmid pin3ERb5. This plasmid contains DNA encoding for a complete electron transport chain, comprising P450 reductase, cytochrome b5 and cytochrome P450 2E1. In order to answer the question if CYP2E1 substrates that yield negative or inconclusive results in the Ames test can be activated by metabolic competent bacterial strains, we used YG7108pin3ERb5 to investigate the following compounds: acetamide, acrylamide, acrylonitrile, allyl chloride, ethyl acrylate, ethyl carbamate, methyl-methacrylate, vinyl acetate, N-nitrosopyrrolidine, trichloroethylene and tetrachloroethylene. N-Nitrosodiethylamine served as a positive control. In addition to these known or proposed CYP2E1 substrates, we investigated the polycyclic aromatic hydrocarbon benzo[alpha]pyrene and the heterocyclic aromatic amines 2-aminofluorene and 2-aminoanthracene. RESULTS: The extensive metabolic competence of the transformed strain is underlined by results showing strong mutagenicity between 10 and 500 micro g N-nitrosopyrrolidine per plate. Unexpectedly, 2-aminoanthracene was mutagenic at a concentration range between 25 and 250 micro g per plate using YG7108pin3ERb5. Moreover, we demonstrate for the first time a clear response of sufficiently characterised allyl chloride in the Ames test at a reasonably low concentration range between 300 and 1500 micro g per plate. We achieved similar results in the parent strain YG7108 with conventional metabolic activation. Without metabolic activation less pronounced mutagenicity occurred, suggesting a contribution of a direct alkylating effect. Propylene oxide is usually contained in allyl chloride as stabilizer at amounts up to 0.09%. Though YG7108 revealed to be very sensitive towards propylene oxide, allyl chloride dissolved in water was not mutagenic, showing that no water soluble compounds contribute to its mutagenicity. None of the remaining compounds showed mutagenic effects using YG7108pin3ERb5. CONCLUSION: YG7108pin3ERb5 and its parent strain YG7108 are sensitive for compounds which are negative in conventional tester strains including N-nitrosodiethylamine, N-nitrosopyrrolidine, propylene oxide and allyl chloride.

Effect of ACE and AT-2 inhibitors on mortality and progression to microalbuminuria in a nested case-control study of diabetic nephropathy in diabetes mellitus type 2: results from the GENDIAN study.

INTRODUCTION: There is an established role of clinical risk factors such as arterial hypertension and smoking in causing cardiovascular morbidity and diabetic nephropathy (DNP). Genetic factors increase the risk for DNP. To examine the genetic risk, we initiated a case-control study with predefined follow-up examinations. We describe the study design and baseline characteristics under special consideration of comedication, and give preliminary results of the 4-year follow-up. METHODS: We enrolled all 477 patients with DNP receiving maintenance hemodialysis in 30 centers in Southern Germany between August 1999 and January 2000. As controls, we enrolled all 482 diabetes mellitus type 2 patients without urinary microalbuminuria in two examinations on consecutive days and without other signs of renal disease in a large diabetes clinic from September 2000 to September 2001. Follow-up examinations are performed 4 and 6 years after inclusion by questionnaire and telephone interview to determine mortality and new morbidity. Controls progressing to novel DNP at follow-up, as defined by semiquantitative dipstick urinary albumin/creatinine ratio > 30 mg/g, are defined as cases in the study's nested case control component. RESULTS: At study inclusion in cases and controls, respectively, mean age was 67.3 +/- 8.2 and 58.1 +/- 11.2 years and duration of diabetes mellitus was 15.6 +/- 9.6 (at dialysis initiation) and 11.0 +/- 8.6 years. 328 controls (of which 25 had died and 14 did not perform urinalysis) were subjected to follow-up at 4 years, at a mean of 3.5 +/- 0.8 years after inclusion. 51.2% (n = 148) of living controls remained normalbuminuric, 33.9% (n = 98) had microor macroalbuminuria, and in 14.9% (n = 43) the dipstick test was inconclusive. There was no significant difference in progression to micro- or macroalbuminuria between controls treated with ACE or AT-2 inhibitors at baseline or not. Renal function as estimated by the abbreviated MDRD formula declined from 86.8 +/- 21.0 to 82.5 +/- 22.3 ml/min/1.73 m2 (p < 0.001). The decline was significant in patients on ACE or AT-2 inhibitors at baseline and not in patients without such medication at baseline. DISCUSSION: GENDIAN is a large case-control study designed to evaluate clinical and genetic determinants of DNP and other complications of long-standing diabetes mellitus type 2. We observed an association of ACE or AT-2 inhibitor therapy with cardiovascular comorbidity and a significant decline in renal function after a 4-year follow-up.

Microcirculatory blood flow, capillary morphology and local oxygen pressure of the hamster amelanotic melanoma A-Mel-3.

Transparent chambers and permanent indwelling catheters were implanted in the dorsal skin flaps of 24 inbred golden Syrian hamsters. After 48 hours, 4 x 10(4) amelanotic melanoma cells (A-Mel-3) were transplanted sc (12 hamsters) in areas exposed for intravital microscopy. A platinum multiwire electrode and techniques for a quantitative analysis of television images were used for measurements of local oxygen pressure (PO2), capillary blood cell velocity, capillary density, and capillary diameter and length, whereas capillary morphology was evaluated by electron microscopy. Compared to the mean local PO2 of the skin flaps of controls (12 hamsters), the mean local PO2 on the tumor surface of melanoma-bearing hamsters decreased with tumor size. Although capillary density of the melanoma was elevated 4 days after tumor transplantation, it decreased significantly until day 12. Of hemodynamic significance were huge platelet conglomerates in short, dilated capillaries. Electron microscopy revealed endothelial hyperplasia, open endothelial junctions, and disintegration of the capillary endothelium. These findings strongly suggest that elevated microvascular resistance, intratumor tissue pressure, and widening of intercapillary distances in the melanoma might significantly diminish the impact of chemotherapeutic treatment.

[Perioperative echocardiography: basic principles]. / Perioperative Echokardiographie: Technische Grundlagen für den Kliniker.

Over the past decades, echocardiography has undergone a continuous evolution in technology that has promoted its clinical application and acceptance throughout perioperative medicine. These technological advances include improvements in transducer development that permit superior imaging quality and a wider selection of probes for epicardial, epiaortic, and surface echocardiography which can also be used in conjunction with multiplane transesophageal echocardiography. Moreover, the addition of Doppler technology and digital acquisition has secured the role of echocardiography as a valuable and relatively noninvasive diagnostic tool for the assessment of cardiovascular disease and hemodynamic monitoring throughout the perioperative period. Therefore, it has become increasingly important for perioperative physicians to understand the basic principles and underlying fundamental concepts pertaining to the technology and physics of echocardiography, as well as its inherent limitations. The current review outlines the modes and applications of different echocardiographic techniques used in perioperative echocardiography including M-mode, two-dimensional echocardiography, and Doppler assessment of blood flow. In addition, the limitations of these techniques and typical artifacts associated with the perioperative use of echocardiography are described.

Quantitative analysis of microvascular structure and function in the amelanotic melanoma A-Mel-3.

Blood cell velocity, capillary diameter, and capillary length were determined in the microcirculation of the amelanotic hamster melanoma A-Mel-3 as well as in s.c. tissue of tumor-free animals. Studies were carried out using a dorsal skin flap chamber, intravital microscopy, and television techniques after transplantation of a 0.5-cu mm piece of tumor tissue. The tumor revealed a special microvascular configuration of short, thin-walled, sometimes dilated capillaries running around the edge of the tumor. Large avascular areas appeared in the center part approximately 5 days after tumor transplantation. Although mean capillary blood cell velocity was not different in tumor-containing and tumor-free preparations, localized irregularities of blood flow were observed close to points of endothelial sacculations. Huge platelet conglomerates were consistently noted in capillaries of the tumor, blocking the blood stream temporarily. Due to discrepancies in microvascular morphology and lack of visible vascularization, large parts of this tumor seem to be inaccessible to tumor treatment. This implies that better vascularization of these regions might enhance the efficiency of cancer treatment. The chamber technique, intravital microscopy, and television methods combined with the subsequent, quantitative microvascular analysis may provide a unique means for direct evaluation of local therapy, particularly during early melanoma growth.

Barium sulfate micro- and nanoparticles as bioinert reference material in particle toxicology.

The inhalation of particles and their exposure to the bronchi and alveoli constitute a major public health risk. Chemical as well as particle-related properties are important factors for the biological response but are difficult to separate from each other. Barium sulfate is a completely inert chemical compound, therefore it is ideally suited to separate these two factors. The biological response of rat alveolar macrophages (NR8383) was analyzed after exposure to barium sulfate particles with three different diameters (40 nm, 270 nm, and 1.3 µm, respectively) for 24 h in vitro (particle concentrations from 12.5 to 200 µg mL-1). The particles were colloidally stabilized as well as fluorescently-labeled by carboxymethylcellulose, conjugated with 6-aminofluorescein. All kinds of barium sulfate particles were efficiently taken up by NR8383 cells and found inside endo-lysosomes, but never in the cell nucleus. Neither an inflammatory nor a cytotoxic response was detected by the ability of dHL-60 and NR8383 cells to migrate towards a chemotactic gradient (conditioned media of NR8383 cells) and by the release of inflammatory mediators (CCL2, TNF-α, IL-6). The particles neither caused apoptosis (up to 200 µg mL-1) nor necrosis (up to 100 µg mL-1). As only adverse reaction, necrosis was found at a concentration of 200 µg mL-1 of the largest barium sulfate particles (1.3 µm). Barium sulfate particles are ideally suited as bioinert control to study size-dependent effects such as uptake mechanisms of intracellular distributions of pure particles, especially in nanotoxicology.

The tyrosine kinase inhibitor CGP 57148 (ST1 571) induces apoptosis in BCR-ABL-positive cells by down-regulating BCL-X.

CGP 57148 is a potent inhibitor of the ABL protein tyrosine kinase and a promising new compound for the treatment of a variety of BCR-ABL-positive leukemias. We used this enzyme inhibitor to characterize the biological effects of BCR-ABL in primary cells and two growth factor-dependent BCR-ABL-transfected cell lines. The effect of CGP 57148 on primary cells is dependent on the stage of differentiation. The growth of maturing chronic myeloid leukemia cells is independent of BCR-ABL in the presence of growth factors. However, the proliferation of leukemic immature cobblestone-forming area cells is almost completely blocked after the inhibition of the BCR-ABL kinase. In the BCR-ABL-transfected cell lines, M07/ p210 and Ba/F3/p185, CGP 57148 induces apoptosis by releasing cytochrome c, activating caspase 3, and cleavage of PARP. No alteration of the expression level of the apoptosis regulator BCL-2 was observed. In contrast, BCL-X was down-regulated after exposure to CGP 57148. Inhibitors of signal transduction proteins such as PI-3 kinase, mitogen-activated protein/extracellular signal-regulated kinase kinase, and Janus-activated kinase 2 pathways were not capable of a comparable down-regulation of BCL-X. The Fas/Fas ligand system was not involved either in the induction of apoptosis by CGP 57148. We conclude that the inhibition of the BCR-ABL kinase by CGP 57148 (a) preferentially inhibits the growth of immature leukemic precursor cells, (b) efficiently reverts the antiapoptotic effects of BCR-ABL by down-regulation of BCL-X, and (c) is more effective than the inhibition of the downstream signal transduction pathways of PI-3 kinase, mitogen-activated protein/extracellular signal-regulated kinase kinase, and Janus-activated kinase 2.