Multiple Lidkantentumore

Ohne Zusammenfassung     

Basic fibroblast growth factor mRNA, bFGF peptide and FGF receptor in epiretinal membranes of intraocular proliferative disorders (PVR and PDR)

Basic fibroblast growth factor (bFGF) has been shown to be involved in epiretinal membrane formation in proliferative vitreoretinal disorders. However, up to now, little knowledge exists, as to the actual cellular source of this potent mitogen.We examined 20 epiretinal membranes from patients with proliferative diabetic retinopathy (PDR) (n = 12) and proliferative vitreoretinopathy (PVR) (n = 8) for the presence of bFGF peptide, fibroblast growth factor receptor-1 (FGFR-1) and bFGF messenger ribonucleic acid (mRNA).Using a specific antibody, we detected bFGF peptide in most (8/10) examined PDR membranes and in all (8/8) PVR membranes. Moreover, we found positive staining for the corresponding receptor.Local production of bFGF in epiretinal membranes was confirmed by nonisotopic in situ hybridisation for bFGF mRNA in some (4/7) examined PDR membranes and some (3/4) examined PVR membranes. All membranes which contained bFGF mRNA were also positive for bFGF peptide.In conclusion, bFGF is produced and stored in epiretinal membranes. Together with the corresponding receptor, bFGF may play a role in the auto- and paracrine control of the proliferative processes at the vitroretinal interface.Abbreviations aFGF acidic fibroblast growth factor - bFGF basic fibroblast growth factor - FGFR-1 fibroblast growth factor receptor-1 - mRNA messenger ribonucleic acid     

Rigid rods with flexible side chains — A route to molecular reinforcement?

Liquid-crystalline main-chain polyesters with polystyrene side chains of different length and number per main chain were synthesized using aromatic hydroxyfunctional polystyrene (PS) macromonomers, terephthalic acid derivatives and tert-butylhydroquinone as co-diol. The molecular weight of the polystyrene side chain was varied in the range from 1000 to 20000. The influence of this novel type of substituent on the solubility, thermal behaviour and miscibility with PS as a flexible matrix polymer is discussed. The properties of the new compounds are compared to those of the respective homopolyester. The graft copolyesters are, depending on the characteristics of the polymeric substituent, soluble in common organic solvents and their thermal transition points are lowered compared to the homopolyester. Compared to blends of the homopolyester, the improvement of miscibility of the polymer-substituted rigid rods with PS as an example for a flexible matrix polymer can be valued as a step to molecular reinforcement.     

Postinjection transmission scanning in myocardial 18F-FDG PET studies using both filtered backprojection and iterative reconstruction.

The aim of the present study was to evaluate the effect of postinjection transmission scanning (Post-Tx) on both the qualitative interpretation and the quantitative analysis of cardiac (18)F-FDG PET images. Furthermore, the accuracy of 2 different methods to correct for emission contamination was studied. An additional aim of this study was to compare images reconstructed with both standard filtered backprojection (FBP) and an iterative reconstruction algorithm (ordered-subset maximization expectation [OSEM]). METHODS: Sixteen patients underwent dynamic (18)F-FDG imaging. Both before injection of (18)F-FDG and after completing the emission scan, a 10-min transmission scan was performed (Pre-Tx and Post-Tx, respectively). Images were reconstructed using both FBP and OSEM. The emission study reconstructed with Pre-Tx was considered to be the gold standard. Emission studies were also reconstructed with Post-Tx, with and without correction for emission contamination. Correction for emission contamination was performed with either transmission image segmentation (TIS) or by estimating the emission bias from the last emission frame (dwell profile [DP] method). All images were then compared by calculating ratios of (18)F-FDG activity between corresponding myocardial segments in each patient. Furthermore, qualitative grading of (18)F-FDG uptake was compared between the studies. RESULTS: The mean ratio of (18)F-FDG activity between segments from FBP-Post and FBP-Pre was 0.78 +/- 0.08. When TIS and DP were used, the mean ratios were 0.80 +/- 0.07 and 0.94 +/- 0.06, respectively. The use of OSEM resulted in, on average, 2% lower values for (18)F-FDG activity as compared with FBP. The mean normalized (18)F-FDG uptake was higher in FBP-Post, especially in segments with decreased (18)F-FDG activity. Only in the case of DP were no significant differences observed as compared with FBP-Pre. In general, qualitative analysis of the images showed that the agreement between the reconstruction methods was comparable with the reproducibility of FBP-Pre. CONCLUSION: Post-Tx for attenuation correction in cardiac (18)F-FDG PET scans resulted in substantial underestimation of (18)F-FDG activity. More accurate results were obtained with correction for emission contamination using DP. Differences in visual assessment of (18)F-FDG images were small. Finally, iterative reconstruction could be used as an alternative to FBP in static (18)F-FDG imaging of the heart.     

Optimization of localized 19F magnetic resonance spectroscopy for the detection of fluorinated drugs in the human liver.

Fluorine MR spectroscopy ((19)F MRS) is an indispensable tool for assessing the pharmacokinetics of fluorinated drugs. Since the metabolism of 5-fluorouracil (5FU), a frequently used cytotoxic drug, is expected to be different in normal liver and in tumor tissue, spatial localization is required for detection by MRS. In this study, three independent signal-to-noise ratio (SNR) optimizations were combined to enable chemical shift imaging (CSI) as a localization method in the detection of 5FU and its metabolites in tumor tissue. First, the hardware was optimized by using circularly polarized coils together with integrated preamplifiers. Second, the optimal pulse angle (Ernst angle) was determined on the basis of T(1) relaxation time measurements of 5FU. Finally, averaging of CSI phase-encoding steps was optimized by using the applied Hamming filter as a weighting function. The combination of these three methods enables the in vivo detection of 5FU and alpha-fluoro-beta-alanine (FBAL) by (19)F MRS, localized in three dimensions in tumor and liver tissue at a time resolution of 4 min at 1.5 Tesla.     

Identification of cytotoxic principles from Fusarium avenaceum using bioassay-guided fractionation

The cytotoxicity of extracts from rice cultures of five Fusarium avenaceum strains against the porcine epithelial kidney cell-line PK-15 was investigated using the Alamar Blue™ assay. After the identification of known fungal metabolites, cytotoxic extracts were fractionated using semi-preparative reversed-phase HPLC and normal phase LC, and the fractions were tested for cytotoxicity. In this way, two different groups of metabolites were identified as the major cytotoxic principles of the extracts. High concentrations of enniatins, especially enniatins B and B1, inhibited the metabolic activity of PK-15 cells. Furthermore, an unidentified metabolite, produced in high amounts by a strain that produced relatively small amounts of enniatins, was also found to be cytotoxic to PK-15 cells. This study shows that enniatins, a group of cyclic depsipeptides, which have been ignored as significant contributors to the toxicity of fungal extracts, may account for most of the observed effect for F. avenaceum.     

Walking exercise in patients with intermittent claudication. Experience in routine clinical practice.

BACKGROUND: In patients with intermittent claudication, exercise in the form of walking is effective in reducing pain and maximising achievable walking distance. However, data are lacking on the implementation of walking exercise in these patients. AIMS: To explore the current behaviour and views of patients with intermittent claudication towards taking walking exercise. DESIGN OF STUDY: Postal questionnaire and focus group meetings. SETTING: Two academic general practice networks (Utrecht and Maastricht Universities) in The Netherlands. METHOD: Three hundred and seventy-five patients with intermittent claudication, selected from the files of general practitioners participating in two academic general practice networks, were sent a postal questionnaire; 216 (58%) were returned. Nine of these responders also attended a focus group meeting. RESULTS: Seventy per cent (151/216) of the patients reported having received advice about walking exercise. If specified, the advice given most often recommended walking in the local neighbourhood (56%, 84/151). Fifty-two per cent (113/216) of all patients actually performed walking exercise and only 32%of them received any kind of supervision. Among the barriers for taking walking exercise, 'comorbidity', 'lack of (specific) advice' and 'lack of supervision' were often mentioned. Among the stimuli to start and continue walking, 'following the doctor's advice', 'relief of complaints' and 'a better general condition' were often mentioned by patients. CONCLUSIONS: Walking exercise was not carried out by almost half of patients with intermittent claudication in this study. Lack of specific advice and supervision were found to be important barriers to taking walking exercise.     

Ultrastructural changes in the conjunctiva of Cynomolgus monkeys following pilocarpine administration?

After a slow-release pilocarpine carrier had been applied for three months, the conjunctival epithelium of two Cynomolgus monkeys showed some remarkable changes in the structure and distribution of the cell types as defined by the authors. The goblet cells (Type I) had almost entirely disappeared, whereas the epithelial cells with secretion granules (Type II) had considerably increased in number. The morphology of the Type II cells gave clear indications of a very active metabolism. In a control experiment, in which two Cynomolgus monkeys treated with a 4% pilocarpine solution for three months, these ultrastructural changes did not occur; it must therefore be assumed that mechanical irritation of the conjunctiva was the cause.     

Anticytoplasmic autoantibodies in the diagnosis and follow-up of Wegener's granulomatosis

Sixty-five patients with biopsy-proven Wegener's granulomatosis (WG), 54 with systemic vasculitis, 22 with relapsing polychondritis, 20 with sarcoidosis, 20 with malignant pulmonary lesions, and 15 with other conditions underwent determination of anticytoplasmic autoantibodies (ACPA) by the indirect immunofluorescence technique on neutrophil cytospin preparations to assess the specificity of ACPA for WG, their sensitivity in relationship to the extent and activity of the disease, and their value for follow-up of WG. Of these 65 patients with WG, 38 were ACPA positive. Two patients in the vasculitis group, best categorized as having microscopic polyarteritis, were ACPA positive. We obtained 125 serum samples from the 65 patients with WG and assigned them to one of two categories (limited or generalized), based on the extent of disease. Each of these categories was then subdivided into "active" or "in remission." Median ACPA titers were significantly different between active disease and remission in each category, as well as between active limited and active generalized disease. All patients whose disease changed from active to in remission had reductions in ACPA titer levels; those who experienced flares had titer increases. Patients with intercurrent illnesses or complications of treatment, mimicking WG flares, did not have titer increases. We conclude that ACPA determined by the indirect immunofluorescence technique is highly specific for WG. The sensitivity is dependent on the extent and activity of WG, and serial titer determinations are valuable in monitoring disease activity.