Formation of covalent deoxyribonucleic acid benzo[a]pyrene 4,5-epoxide adduct in mouse and rat skin

The covalently bound products of [³H]benzo[a]pyrene (BP) were determined in the DNA from the skin of mice and rats. The quality and the distribution of bound products was similar. The formation of products corresponding to 4,5-dihydro-4,5-epoxy benzo[a]pyrene (BPE) and to a further metabolite of 9-hydroxybenzo[a]pyrene bound to DNA were found in the 2 species at the 24 h end point.     

Persistence of benzo[a]pyrenediolepoxide DNA adduct in mouse skin

The covalently bound products of [³H] benzo[a]pyrene (BP) were determined in the DNA isolated from the skin of mice 3 weeks after application of the carcinogen. In the relatively repidly proliferating skin the persistence of BP-DNA adducts was observed, 50% of which were unmodified nucleosides. Small amounts of (7R) BPDE I-dG adduct (5% from the initial formation) were found after 3 weeks. The minor adducts observed at 18 h after treatment were excised.     

Cross reactions to antigens causing hypersensitivity pneumonitis

The sera of patients with asthma, aspergillosis, pigeon breeder's disease, farmer's lung, and a hypersensitivity pneumonitis in textile plant workers were screened by gel diffusion against a variety of fungal antigens and dust extracts. Patients with hypersensitivity pneumonitis were especially prone to develop precipitating antibody to numerous airborne antigens. From the results it was concluded that patients with hypersensitivity pneumonitis form precipitating antibodies to definite groups of antigens in their environment. Most of the patients had precipitins to house dust that formed lines of identity with fungi and thermophilic actinomycetes.     

Synthesis and properties of branched polyethylene/high‐density polyethylene blends using a homogeneous binary catalyst system composed of early and late transition metal complexes

Branched polyethylene/high‐density polyethylene blends (BPE/HDPE) with a wide range of molecular weights, melt flow indexes (MFI), and intrinsic viscosity were prepared using the homogeneous binary catalyst system composed by Ni(α‐diimine)Cl₂ ( 1 ) (α‐diimine = 1,4‐bis(2,6‐diisopropylphenyl)‐acenaphthenediimine) and {Tp^Ms*}TiCl₃ ( 2 ) (Tp^Ms* = hydridobis(3‐mesitylpyrazol‐1‐yl)(5‐mesitylpyrazol‐1‐yl)) activated with MAO and/or TIBA in hexane at two different polymerization temperatures (30 and 55 °C) and by varying the nickel loading molar fraction (x_Ni). At all temperatures, a non‐linear correlation between the x_Ni and the productivity was observed, suggesting the occurrence of a synergistic effect between the nickel and the titanium catalyst precursors, which is more pronounced at 55 °C. The molecular weight of the BPE/HDPE blends considerably decreases with increasing Al/M molar ratio. The melt flow indexes (MFI) and intrinsic viscosities (η) are strongly affected by x_Ni, but the melting temperatures are nearly constant, 132 ± 3 °C. Dynamic mechanical thermal analysis (DMTA) shows the formation of different polymeric materials where the stiffness varies according to the x_Ni and temperature used in the polymerization reaction. The surface morphology of the BPE/HDPE blends studied by scanning electron microscopy (SEM) revealed a low miscibility between the PE phases resulting in the formation of a “sandwich structure” after etching with o‐xylene.

     

影响洁净管道可清洗性因素的分析——对ASME BPE-SD篇中“死角”的定量分析

对ASME BPE标准中的＂可清洗性＂,＂死角L/D≤2＂进行分析和讨论。提出一些有效的经验方法,推导出理论计算公式,演示计算过程,根据计算结果简述工艺因素对死角的影响,最后提供在工程设计中死角的逻辑处理流程。     

Evaluation of the multipotent character of human foreskin-derived precursor cells

In the present study, the trilineage differentiation capacity of human foreskin-derived precursor cells (hSKP) was evaluated upon exposure to various (non)commercial (i and ii) ectodermal, (iii) mesodermal and (iv) endodermal differentiation media.

(i)

Upon sequential exposure of the cells to keratinocyte growth (CnT-07® or CnT-057®) and differentiation (CnT-02® or Epilife®) media, keratinocyte-like cells (filaggrin⁺/involucrin⁺) were obtained. The preferred keratinocyte differentiation strategy was exposure to CnT-07®.

(ii)

When hSKP were subsequently exposed to NeuroCult® media, cells underwent a weak neuro-ectodermal differentiation expressing nestin, myelin binding protein (MBP), vimentin and alpha-foetoprotein (AFP). Sequential exposure to NPMM® and NPDM® generated cells with an inferior neuro-ectodermal phenotype (nestin⁺/vimentin⁺/MBP⁻/AFP⁻).

(iii)

Upon exposure of hSKP to insulin-transferrin-selenite (ITS) and dexamethasone, small lipid droplets were observed, suggesting their differentiation potential towards adipocyte-like cells.

(iv)

Finally, after sequential exposure to hepatogenic growth factors and cytokines, an immature hepatic cell population was generated. The presence of pre-albumin suggests that a sequential exposure strategy is here superior to a cocktail approach.

In summary, a considerable impact of different (non)commercial media on the lineage-specific differentiation efficiency of hSKP is shown. In addition, we demonstrate here for the first time that, in a suitable keratinocyte stimulating micro-environment, hSKP can generate keratinocyte-like progeny in vitro.     

Evaluation of the multipotent character of human adipose tissue-derived stem cells isolated by Ficoll gradient centrifugation and red blood cell lysis treatment

In the present study, the multipotent potential of two differential isolated human adipose-derived stem cell (hADSC) populations was evaluated. More specifically, hADSC isolated by means of classical Ficoll (F) gradient centrifugation were compared to hADSC isolated by means of red blood cell (RBC) lysis treatment and subsequent cultivation as 3D spheres.No significant difference in the genotypic expression of the multipotent markers Oct-4, Sox-2, Nanog, Klf-4 and cMyc could be observed between both isolation methods. Upon adipogenic and osteogenic differentiation, both hADSC populations showed lipid droplet accumulation and mineral deposition, respectively. Although, a more pronounced mineral deposition was observed in hADSC-RBC, suggesting a higher osteogenic potential. Upon exposure to keratinogenic media, both hADSC populations expressed the keratinocyte markers filaggrin and involucrin, evidencing a successful keratinogenic differentiation. Yet, no differences in expression were observed between the distinctive isolation procedures. Finally, upon exposure to neurogenic differentiation media, a significant difference in marker expression was observed. Indeed, hADSC-RBC only expressed vimentin and nestin, whereas hADSC-F expressed vimentin, nestin, NF-200, MBP and TH, suggesting a higher neurogenic potential.In summary, our data suggest that the choice of the most efficient isolation procedure of hADSC depends on the differentiated cell type ultimately required.