Alternating copolymerization of carbon dioxide and propylene oxide in the presence of organometallic catalysts

Carbon dioxide and propylene oxide (PO) were copolymerized using diethylzinc in addition with benzenedi- and triols, aliphatic diols and triols, and aminophenols as catalyst systems. A large amount of CO₂/PO alternating copolymer, {poly(propylene carbonate), poly(oxycarbonyloxypropylene), of high molecular weight was obtained using the homogeneous (C₂H₅)₂Zn/pyrogallol (2:1 by mole) system ( 1 ). The (C₂H₅)₂Zn/o-aminophenol system ( 2 ) (also homogeneous) appeared to be much less active in the copolymerization of CO₂ with PO than the former one. From the other studied systems, that appeared to be heterogeneous, (C₂H₅)₂Zn/resorcinol (1:1 by mole) was the most active one, but less active than the system 1 . Further, the copolymerization of CO₂ and PO was studied in the presence of the (C₂H₅)₂Zn/resorcinol (1:1 by mole) system at various temperatures and in reaction media of different basicity. On the basis of the obtained results of the copolymerization of CO₂ with PO and of measurements of the quantity of ethane evolved in the reactions between the catalytic systems' components, structures of several catalysts, particularly homogeneous ones, are suggested and some aspects of the copolymerization mechanism are discussed.     

Fünf neue Menacanthus-Arten aus mitteleuropäischen Singvögeln

Zusammenfassung Aus mitteleuropäischen Singvögeln werden die folgenden neuen Menacanthus-Arten beschrieben: M. festivus nov. spec. von Fringilla coelebs, M. pius nov. spec. von Turdus merula, M. polonicus nov. spec. von Turdus pilaris, M. vistulanus nov. spec. von Sylvia borin und M. wipszyckii nov. spec. von Chloris chloris. Die Tatsache, daß das insgesamt aus mehreren Funden und besonders für M. pius nov. spec. aus zahlreichen Exemplaren bestehende, dieser Arbeit zugrunde liegende Untersuchungsmaterial fast ausschließlich Weibchen enthält, wird als Ausgangspunkt für eine Diskussion des Speziesbegriffs bei uniparentalen Mallophagenarten herangezogen. Zur Klärung dieser auch evolutionstheoretisch bemerkenswerten Problematik wird ein Forschungsprogramm für Menacanthus-Arten entwickelt.Mit 10 Textabbildungen     

Image processing techniques for noise removal, enhancement and segmentation of cartilage OCT images

Osteoarthritis, whose hallmark is the progressive loss of joint cartilage, is a major cause of morbidity worldwide. Recently, optical coherence tomography (OCT) has demonstrated considerable promise for the assessment of articular cartilage. Among the most important parameters to be assessed is cartilage width. However, detection of the bone cartilage interface is critical for the assessment of cartilage width. At present, the quantitative evaluations of cartilage thickness are being done using manual tracing of cartilage-bone borders. Since data is being obtained near video rate with OCT, automated identification of the bone-cartilage interface is critical. In order to automate the process of boundary detection on OCT images, there is a need for developing new image processing techniques. In this paper we describe the image processing techniques for speckle removal, image enhancement and segmentation of cartilage OCT images. In particular, this paper focuses on rabbit cartilage since this is an important animal model for testing both chondroprotective agents and cartilage repair techniques. In this study, a variety of techniques were examined. Ultimately, by combining an adaptive filtering technique with edge detection (vertical gradient, Sobel edge detection), cartilage edges can be detected. The procedure requires several steps and can be automated. Once the cartilage edges are outlined, the cartilage thickness can be measured.     

The striopallidal pathway is involved in antiparkinsonian-like effects of the blockade of group I metabotropic glutamate receptors in rats

The aim of the study was to examine the influence of the blockade of group I metabotropic glutamate receptors (mGluRs) on the haloperidol-induced catalepsy and proenkephalin mRNA expression in the rat striatum. Bilateral, intrastriatal injection of AIDA ((RS)-1-aminoindan-1,5-dicarboxylic acid, 3-15 microg/0.5 microl), a selective antagonist of group I mGluRs, inhibited catalepsy induced by haloperidol (0.5 mg/kg i.p.). Repeated intrastriatal AIDA administrations (3 x 15 microg/0.5 microl, 3 h apart) counteracted the haloperidol-induced (3 x 1.5 mg/kg s.c., 3 h apart) increase in the proenkephalin mRNA expression in that structure. The present study indicates that the blockade of the striatal group I mGluRs may inhibit parkinsonian akinesia by normalizing the function of the striopallidal pathway.     

Investigations on the catalytic systems diethylzinc/Di- and trihydroxybenzenes in the copolymerization of carbon dioxide with propylene oxide

Investigations on the reactions of diethylzinc ( 1 ) with resorcinol ( 2 ) and phloroglucinol ( 8 ) were carried out for different mole ratios of the reactants. It was found that the reaction of 1 with 2 at a mole ratio of 1:1 is a two step process. In the first step 1 reacts very rapidly with half of applied 2 yielding di(ethylzinc) resorcinolate ( 6 ), which then reacts slowly with the remaining amount of 2 . It was found that zinc 3-ethylzincoxyphenolate resorcinolate ( 5 ) formed in the second step is an active catalyst of the copolymerization reaction of carbon dioxide with propylene oxide. The reaction of 1 with 8 shows a similar course.     

Gene transfer by adenovirus-mimetic peptides in the presence of a cationic lipid and/or adenovirus. Analysis of the contribution of the viral and nonviral components

Summary.  Peptide and cationic lipid-based gene transfer vectors have shown promise for gene therapy but are still less efficient than viral gene transfer vectors. We have examined the mechanism of gene transfer of different adenovirus-mimetic peptides in the presence and absence of a cationic lipid, lipofectamine and/or adenovirus with the aim of improving the design of nonviral vectors for efficient gene transfer. Three polylysine-adenovirus-mimetic peptides were synthesised and examined for their efficacy for gene transfer. Transfection levels in four cell lines: adenovirus permissive human tracheal epithelial (56FHTE8o⁻), human lung carcinoma (A549), human colon carcinoma (Caco-2) cells, and adenovirus low-permissive Chinese hamster ovary (CHO) cells, were examined. The polylysine-adenovirus-mimetic peptides increased the level of transfection of a reporter transgene in all cell lines. Transfection was substantially increased when an adenovirus was added to cells after pre-incubation with the vector complexes. Formulation of the peptide vector complexes with lipofectamine increased their transfection efficacy and the subsequent addition of an adenovirus increased transfection levels even further but only in permissive cells. Pre-incubation of cells with lipofectamine-peptide vector complexes increased cell binding of the adenovirus but uptake was only increased in intermediate- or non-permissive cells. The addition of lipofectamine increased transgene expression of a recombinant adenovirus in non-permissive cells but not in permissive cells. Enhancement with an adenovirus of peptide vector gene transfer is probably due to more efficient endosome escape while enhancement of gene transfer by peptide vectors complexed to lipofectamine is due to an increase in cellular binding and/or internalisation of the adenovirus. Received February 8, 2002; accepted August 23, 2002     

Influence of exposure mode on vinyl chloride action

Rats were subjected to 4 h continuous or intermittent exposure to vinyl chloride (VC) at different time-weighted average concentrations (15, 50, 150, 500 and 15,000 mg/m³). Hepatic non-protein sulfhydryl content (NPSH) and excretion of thiodiglycolic acid (TdGA) in urine were determined. VC at concentrations from 50 mg/m³ to 15,000 mg/m³ caused a dose-dependent depression of NPSH, but no difference in the magnitude of this depression induced by continuous or intermittent exposure at the same average concentration of VC was noted. At average concentrations of 50 mg/m³ and 150 mg/m³, the urinary excretion of TdGA under continuous exposure did not differ from that under intermittent exposure, whereas at VC concentrations of 500 mg/m³ and 15,000 mg/m³ it was higher following continuous exposure.     

Assessment of the Effect of Selenium Supplementation on Production of Selected Cytokines in Women with Hashimoto’s Thyroiditis

The impact of selenium on the course of Hashimoto’s thyroiditis (HT) was mainly assessed by monitoring the titer of antithyroid autoantibodies in most of the studies conducted hitherto. On the other hand, the imbalance in activity of T cells such as Th1, Th2, Th17, and Treg may be relevant in the pathogenesis of this disease. Hence, the assessment of changes in the secretion of cytokines by these cells during selenium supplementation in patients with HT seems to be an important issue and was the main goal of this study. A further aim was to search for correlations among these cytokines, as well as markers of thyroid function, selenium/iodine status in the body, and other biochemical parameters. The group of 29 women with newly diagnosed Hashimoto’s thyroiditis was supplemented with selenium in a dose of 100 µg/day for 6 months. Immunological parameters: interferon γ, tumor necrosis factor α, chemokine CXCL10, interleukin 4, interleukin 1β, interleukin 17, transforming growth factor β, and C-reactive protein, as well as selenium status parameters were determined in serum twice, i.e., before and after supplementation. Selenium supplementation was associated with a change in the production of two cytokines: interferon γ and interleukin 1β, for which a decrease and an increase in concentration were observed, respectively. The partial least squares (PLS) model revealed the presence of many relevant correlations among analyzed parameters. The stage of HT development, degree of thyroid dysfunction, and selenium supplementation of diet are interdependent factors which shape the profile of some cytokines secreted by cells participating in the autoimmunity process.     

Double teeth: evaluation of 10-years of clinical material

The aim of the study was to evaluate 10-years of clinical material referring to the rare dental abnormality of double teeth. The study material consisted of case records, operation-books and radiographic or photographic documentation on patients treated in the Department of Oral Surgery, Silesian Medical University, Katowice, from the 1st of June 2000 to the 31st of May 2010. The following features were considered important: age and sex, the reason why the patient reported for treatment, general state of health, the time of recognition and type of double teeth, location of double teeth, complaints and disturbances connected with double teeth, types of radiographs, the radiographic and macroscopic appearance of double teeth and treatment method. Diagnoses were as follows: eight conrescent teeth, two fused teeth, two geminated teeth and one invaginated tooth. The anomaly of a deciduous tooth was referred to in one case only. Double teeth were most often seen in the region of maxillary incisors and molars but rarely in the mandible. The region of incisors was affected chiefly in children and the region of molars in adults. Double incisors are usually recognized prior to treatment whereas double molars as late as during their extraction. In many cases, neither intraoral radiographs nor pantomographs help to confirm double teeth or provide sufficient information to plan the treatment. In such a situation, CT or CBCT should be used in addition to imaging diagnostics. Double teeth among incisors are usually accompanied by occlusal disorders. Therefore the therapeutic management is conducted by a team, including orthodontists.     

Melatonin-induced modulation of glucose metabolism in primary cultures of rabbit kidney-cortex tubules

The effect of melatonin on glucose metabolism in the presence and absence of insulin has been investigated in the primary cultures of renal tubules grown in a defined medium. In the absence of glucose in the medium containing 5 microg/mL of insulin and 2 mm alanine + 5 mm glycerol + 0.5 mm octanoate, 100 nm melatonin stimulated both glucose and lactate synthesis, while in the medium devoid of insulin melatonin action was negligible. Melatonin-induced increase in glucose and lactate synthesis was accompanied by an enhancement of alanine and glycerol consumption. In view of measurements of [U-14C]L-alanine and [U-14C]L-glycerol incorporation into glucose, it is likely that melatonin increased alanine utilization for glucose production, while accelerated lactate synthesis was because of an enhanced glycerol consumption. As (i) 10 nm luzindole attenuated the stimulatory action of melatonin on glucose formation and (ii) the indole induced a decrease in intracellular cAMP level, it seems likely that in renal tubules melatonin binds to ML1 membrane receptor subtype. In view of a decline of intracellular fructose-1,6-bisphosphate content accompanied by a significant rise in hexose-6-phosphate and glucose levels, melatonin might result in an acceleration of flux through fructose-1,6-bisphosphatase probably because of an increase in the active, dephosphorylated form of this enzyme. Thus, the administration of melatonin in combination with insulin might be beneficial for diabetic therapy because of protection against hypoglycemia.