Ciprofibrate--racemate and enantiomers: effects of a four-week treatment on male inbred Fischer rats. A biochemical and morphological study

Ciprofibrates (racemate and both enantiomers, Raccip, R- and Scip) were administered orally in doses of 1 and 10 mg/kg once daily over 28 days to male inbred Fischer 344 rats, age 90-110 days at the beginning of the experiment. Body mass gain was observed in all groups. The 1 mg groups showed almost no difference to the control group. The 10 mg groups exhibited less body mass gain, most pronounced in the Scip group. Liver masses were increased in a dose dependent manner up to more than 200%, only the 10 mg Scip group was not significantly different from the 1 mg group which exhibited an increase in liver weight to about 175%. Also the kidney weights increased to 130%, whereas thymus and spleen weights were decreased in the high dose groups. Liver microsomal cytochromes P450 (P450) concentrations were not altered in the 1 mg groups and distinctly lowered in the 10 mg groups. Ethoxyresorufin and ethoxycoumarin O-deethylations were lowered in all experimental groups in a dose dependent manner, after administration of the high doses down to 30% of the control levels or less. Pentoxyresorufin O-depentylation, however, was increased in all 1 mg groups. In the high dose groups it was not altered. Ethylmorphine N-demethylation was decreased after administration of the high doses by about 50%, but only Scip decreased this reaction also after administration of the low dose. NADPH/Fe2+-stimulated microsomal luminol and lucigenin amplified chemiluminescence was increased, whereas hydrogen peroxide formation was depressed even by the low doses to 50% of the normal values, to about 25% by the high doses. Microsomal lipid peroxidation, however, was only slightly or not influenced. Glutathion concentrations (in the reduced and the oxidized form) were increased in a dose dependent manner by about 20 to 30%, the concentration of lipid peroxides was not significantly influenced. Thus, the effects of the enantiomers were not different and were similar to those of the racemate. In serum, cholesterol and triglycerides were only moderately lowered. Albumin concentrations were significantly enhanced in all groups, total proteins after 1 mg/kg Raccip only. Serum bilirubins were not altered, and among the indicator enzymes for liver damage only ALAT, alkaline phosphatase and the dehydrogenases were increased, in no case higher than twofold. Histologically distinct effects were seen after administration of both doses, more pronounced after 10 mg/kg, but with no differences between the enantiomers and Raccip: marked hypertrophy of the hepatocytes, reduced staining of the nuclei, strongly acidophilic granulated cytoplama, no basophilia of the cell bodies, loss of glycogen. These changes were most pronounced around the central veins. Hepatocyte apoptoses also were observed. By immunohistochemistry an increased staining was seen for all P450 isoforms tested (1A1, 2B1, 2E1, 3A2 and 4A1), predominantly perivenously and most pronounced after administration of the high doses without differences between Rcip, Scip or Raccip (preliminary results). By electron microscopy a moderate proliferation of peroxisomes after treatment with 1 mg/kg Cips with a ratio between mitochondria and peroxisomes of about 1:1 (controls: 10:1) was observed, and the peroxisomes were a more heterogeneous population. The relative portions of glycogen and both forms of the ER decreased. Treatment with 10 mg/kg Rcip, Scip or Raccip led to a strong increase in the number of peroxisomes, in some hepatocytes the ratio between mitochondria and peroxisomes was 1:3 with an increased heterogeneity among the peroxisomes evidenced by a broad range of electron densities. Most peroxisomes lacked a nucleoid. Thus, the biochemical effects differed only slightly and the morphological effects of the enantiomers were not different and were similar to those of the racemate.     

Charge storage and its dynamics in porous polytetrafluoroethylene (PTFE) film electrets

The outstanding space charge storage stability of porous polytetrafluoroethylene (PTFE) film electrets is studied by isothermal surface potential decay measurements and open-circuit thermally stimulated discharge (TSD) experiments after corona charging at room and elevated temperatures, or corona charging at RT and then aging at different temperatures. Charge storage properties of porous PTFE, nonporous PTFE (Teflon/spl reg/ PTFE) and nonporous FEP (Teflon/spl reg/ FEP) electrets are compared. The results show that porous PTFE has the best charge storage stability of organic materials for both negative and positive charges, especially at high temperatures. The structure of porous PTFE, investigated by a scanning electron microscope (SEM), is important for understanding the electret properties of this material. Charge dynamics, including the influence of environmental humidity and temperature on charge stability and shift of mean charge depth, and the kinetics of detrapped charges for the porous PTFE film electrets were also investigated by means of isothermal surface potential decay measurements and analysis of the TSD current spectra in combination with the heat pulse technique. It is found that from about RT to 200/spl deg/C slow retrapping plays a dominant role; from about 200/spl deg/C to 300/spl deg/C fast retrapping controls the transport.     

Pharmacotherapeutic compass 1998

The Central Medical Pharmaceutical Committee of the Health Insurance Council informs the medical profession annually about the effects of drugs through the Pharmacotherapeutical Compass. The 1998 edition now contains a chapter on pharmacokinetics as well. Compared with previous editions the main alterations of the contents concern an introduction and advice on the antidepressants, two protocols with respect to the medical treatment of patients suffering from epilepsy, advice with respect to oral drugs for the treatment of inflammatory bowel disease, an introduction and advice regarding the treatment of allergic rhinitis, the treatment of patients suffering from AIDS with antiretroviral drugs, the treatment of genital herpes, the taking of insulin lispro by patients with diabetes and the taking of bisphosphonates to prevent or to treat osteoporosis. Two corrections to the 1998 edition are given.     

P(VDF/CTFE)共聚物薄膜的驻极体行为

通过不同条件下的正负电晕充电,等温表面电位衰减测量,热刺激放电（TSD）电流谱分析和热脉冲技术,首次研究了偏氟乙烯（VDF）和三氟氯乙烯（CTFE）共聚物P（VDF／CTFE）的驻极体性质,结果指出：共聚物驻极体的空间电荷热稳定性明显优于PVDF;TSD谱分析说明这种材料驻极体也是极性驻极体,即体内同时包含有偶极和空间电荷。本文还对样品的正负电晕充电后的电荷储存稳定性做了对比;研究了材料的能阱分布,确定了样品在不同温度电晕充电时平均电荷重迁移规律。     

Electron beam poling of thin fluoropolymer layers

Electron beam poling by use of a scanning electron microscope was developed and applied to thin polymer layers. The electron beam charging process was studied by measurement of the surface potential, dependent on the acceleration voltage. The induced orientation of CF₂ dipole groups of the ferroelectric copolymer vinylidene fluoride/trifluoroethylene was detected by means of IR spectroscopy as well as by nonlinear optical methods. Using electron beam microlithography, microscopic polarization structures have been written into thin fluoropolymer layers by means of a direct, computer-controlled writing process; they were read out through potential contrast images as well as by means of SHG (second harmonic generation)     

Evaluation of the role of waste in a truck manufacturing line using simulation

In their never-ending search to improve manufacturing performance, companies try to eliminate all sources of waste. In this paper, we describe how the effects of the elimination of waste on performance measures such as lead time and overtime costs can be estimated using logistical simulation. This is illustrated using a real-life case study that was conducted in the repair department of a truck cabin factory. In this department, cabs are controlled and if necessary repaired. The first part of the paper describes how bottlenecks were determined for both the present layout and for a proposed layout change. This turned out to be difficult, as several product flows intertwine. Modelling was made complex by these interactions, as they caused deadlock phenomena. The second part of the paper represents a sensitivity analysis, which evaluates the effects of different types of waste, such as machine breakdowns, inadequate buffer size and production time variance.     

FULLSPECTRUM: a new PV wave making more efficient use of the solar spectrum

The project FULLSPECTRUM — an Integrated Project (IP) in the terminology of the European Commission — pursues a better exploitation of the FULL solar SPECTRUM by (1) further developing concepts already scientifically proven but not yet developed and (2) by trying to prove new ones in the search for a breakthrough in photovoltaic (PV) technology. More specific objectives are the development of: (a) III–V multijunction cells (MJC), (b) solar thermo-photovoltaic (TPV) converters, (c) intermediate band (IB) materials and cells (IBC), (d) molecular-based concepts (MBC) for full PV utilisation of the solar spectrum and (e) manufacturing technologies (MFG) for novel concepts including assembling. MJC technology towards 40% efficiency will be developed using lower cost substrates and high light concentration (up or above 1000 suns). TPV is a concept with a theoretically high efficiency limit because the entire energy of all the photons is used in the heating process and because the non-used photons can be fed back to the emitter, therefore helping in keeping it hot. In the IBC approach, sub-bandgap photons are exploited by means of an IB. Specific IB materials will be sought by direct synthesis suggested by material-band calculations and using nanotechnology in quantum dot (QD) IBCs. In the development of the MBC, topics such as the development of two-photon dye cells and the development of a static global (direct and diffuse) light concentrator by means of luminescent multicolour dyes and QDs, with the radiation confined by photonic crystals, will be particularly addressed. MFG include optoelectronic assembling techniques and coupling of light to cells with new-optic miniconcentrators.