Anatomy-corresponding method of IMRT verification

Background

During a proper execution of dMLC plans, there occurs an undesired but frequent effect of the dose locally accumulated by tissue being significantly different than expected. The conventional dosimetric QA procedures give only a partial picture of the quality of IMRT treatment, because their solely quantitative outcomes usually correspond more to the total area of the detector than the actually irradiated volume.

Aim

The aim of this investigation was to develop a procedure of dynamic plans verification which would be able to visualize the potential anomalies of dose distribution and specify which tissue they exactly refer to.

Materials & methods

The paper presents a method discovered and clinically examined in our department. It is based on a Gamma Evaluation concept and allows accurate localization of deviations between predicted and acquired dose distributions, which were registered by portal as well as film dosimetry. All the calculations were performed on the self-made software GammaEval, the γ-images (2-dimensional distribution of γ-values) and γ-histograms were created as quantitative outcomes of verification.

Results

Over 150 maps of dose distribution have been analyzed and the cross-examination of the gamma images with DRRs was performed.

Conclusions

It seems, that the complex monitoring of treatment would be possible owing to the images obtained as a cross-examination of γ-images and corresponding DRRs.     

Serodiversity of opsonic antibodies against Enterococcus faecalis--glycans of the cell wall revisited

In a typing system based on opsonic antibodies against carbohydrate antigens of the cell envelope, 60% of Enterococcus faecalis strains can be assigned to one of four serotypes (CPS-A to CPS-D). The structural basis for enterococcal serotypes, however, is still incompletely understood. Here we demonstrate that antibodies raised against lipoteichoic acid (LTA) from a CPS-A strain are opsonic to both CPS-A and CPS-B strains. LTA-specific antibodies also bind to LTA of CPS-C and CPS-D strains, but fail to opsonize them. From CPS-C and CPS-D strains resistant to opsonization by anti-LTA, we purified a novel diheteroglycan with a repeating unit of →6)-β-Galf-(1→3)- β-D-Glcp-(1→ with O-acetylation in position 5 and lactic acid substitution at position 3 of the Galf residue. The purified diheteroglycan, but not LTA absorbed opsonic antibodies from whole cell antiserum against E. faecalis type 2 (a CPS-C strain) and type 5 (CPS-D). Rabbit antiserum raised against purified diheteroglycan opsonized CPS-C and CPS-D strains and passive protection with diheteroglycan-specific antiserum reduced bacterial counts by 1.4-3.4 logs in mice infected with E. faecalis strains of the CPS-C and CPS-D serotype. Diheteroglycan-specific opsonic antibodies were absorbed by whole bacterial cells of E. faecalis FA2-2 (CPS-C) but not by its isogenic acapsular cpsI-mutant and on native PAGE purified diheteroglycan co-migrated with the gene product of the cps-locus, suggesting that it is synthesized by this locus. In summary, two polysaccharide antigens, LTA and a novel diheteroglycan, are targets of opsonic antibodies against typeable E. faecalis strains. These cell-wall associated polymers are promising candidates for active and passive vaccination and add to our armamentarium to fight this important nosocomial pathogen.     

Changes in electric charge and phospholipids composition in human colorectal cancer cells

Cancer cells perform their malicious activities through own cell membranes that screen and transmit inhibitory and stimulatory signals out of the cells and into them. This work is focused on changes of phospholipids content (PI—phosphatidylinositol, PS—phosphatidylserine, PE—phosphatidylethanolamine, PC—phosphatidylcholine) and electric charge that occur in cell membranes of colorectal cancer of pT3 stage, various grades (G2, G3) and without/with metastasis. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC (high-performance liquid chromatography). The surface charge density of colorectal cancer cell membranes was measured using electrophoresis. The measurements were carried out at various pH of solution. It was shown that the process of cancer transformation was accompanied by an increase in total amount of phospholipids as well as an increase in total positive charge at low pH and total negative charge at high pH. A malignant neoplasm cells with metastases are characterized by a higher PC/PE ratio than malignant neoplasm cells without metastases. (Mol Cell Biochem 276: 113–119, 2005)     

Efficient use of synchrotron radiation for macromolecular diffraction data collection

In recent years, number of X-ray synchrotron beam lines dedicated to collecting diffraction data from macromolecular crystals has exceeded 50. Indeed, today most protein and nucleic acid crystal structures are solved and refined based on the synchrotron data. Collecting diffraction data on a synchrotron beam line involves many technical points, but it is not a mere technicality. Even though the available hardware and software have become more advanced and user-friendly, it is always beneficial if the experimenter is aware of the problems involved in the data collection process and can make informed decisions leading to the highest possible quality of the acquired diffraction data. Various factors, important for the success of data collection experiments and their relevance for different kinds of applications, are discussed.     

Selenium level in benign and cancerous prostate

The dietary microelement selenium (Se) has been proposed as a potential chemopreventive agent for prostate cancer. This element is present in various amounts in all tissues. Little information is available on Se level in patients with prostate gland disorders. The levels of Se in prostatic gland of patients with prostate cancer, benign prostate hyperplasia, and healthy controls were examined. The Se level for benign prostate hyperplasia (156±30.6 ng/g) was the same as in the control group (157±26.0 ng/g), but in the gland of prostate cancer patients (182±34.1 ng/g wet weight), the Se level was significantly (p<0.01) higher than in both healthy controls and benign prostate hyperplasia. Thus, the Se level in human healthy controls is lower than in kidney and liver but higher compared with other tissues.     

Antiradical and anti-H2O2 properties of polyphenolic compounds from an aqueous peppermint extract

Polyphenolic compounds such as eriocitrin, luteolin-7-O-rutinoside, diosmin, hesperidin, narirutin, isorhoifolin, rosmarinic and caffeic acids were identified in an aqueous extract (Ex) obtained from peppermint leaves (Menthae x piperitae folium). The content of polyphenols in Ex was as follows: eriocitrin 38%, luteolin-7-O-rutinoside 3.5%, hesperidin 2.9%, diosmin 0.8%, isorhoifolin 0.6%, narirutin 0.3%, rosmarinic acid 3.7% and caffeic acid 0.05%. The strongest antiradical activity (determined as DPPH* scavenging features) was observed for luteolin-7-O-rutinoside, eriocitrin and rosmarinic acid. Caffeic acid and hesperidin revealed a lower antiradical activity while isorhoifolin, narirutin and diosmin showed the lowest activity. The strongest anti-H2O2 activity was observed for eriocitrin, a little lower for rosmarinic acid. The rate of hydrogen peroxide scavenging activity displayed by luteolin-7-O-rutinoside and caffeic acid was lower than that of rosmarinic acids. Hesperidin appeared to be a very weak scavenger of hydrogen peroxide. Almost no anti-H2O2 activity was demonstrated for diosmin, narirutin and isorhoifolin. Among examined flavonoids, the strongest antiradical and anti-H2O2 activity was shown for compounds with two hydroxy groups bound to the Bring in ortho position in relation to each other. Replacement of one hydroxy group in the Bring with a methoxy group or removing one hydroxy group leads to decrease of antiradical and anti-H2O2 activity of flavonoids. Our results suggest that eriocitrin is a powerful peppermint antioxidant and a free radical scavenger.     

Oocyte nucleus controls progression through meiotic maturation

We analyzed progression through the meiotic maturation in oocytes manipulated to replace the prophase oocyte nucleus with the nucleus from a cumulus cell, a pachytene spermatocyte or the pronucleus from a fertilized egg. Removal of the oocyte nucleus led to a significant reduction in histone H1 kinase activity. Replacement of the oocyte nucleus by a pronucleus followed by culture resulted in premature pseudomeiotic division and occasional abnormal cytokinesis; however, histone H1 kinase activity was rescued, microtubules formed a bipolar spindle, and chromosomes were condensed. In addition to the anomalies observed after pronuclear transfer, those after transfer of the nucleus from a cumulus cell or spermatocyte included a dramatically impaired ability to form the bipolar spindle or to condense chromosomes, and histone H1 kinase activity was not rescued. Expression of a cyclin B-YFP in enucleated oocytes receiving the cumulus cell nucleus rescued histone H1 kinase activity, but spindle formation and chromosome condensation remained impaired, indicating a pleiotropic effect of oocyte nucleus removal. However, when the cumulus cell nucleus was first transformed into pronuclei (transfer into a metaphase II oocyte followed by activation), such pronuclei supported maturation after transfer into the oocyte in a manner similar to that of normal pronuclei. These results show that the oocyte nucleus contains specific components required for the control of progression through the meiotic maturation and that some of these components are also present in pronuclei.     

Control of Taenia solium taeniasis/cysticercosis: from research towards implementation

Theoretically, considering the biology of its transmission and reservoirs, global eradication of Taenia solium taeniasis and cysticercosis is feasible. Recently much progress has been made in research on diagnosis, treatment and prevention of human taeniasis and porcine cysticercosis, although more operational research is still needed. In spite of this, global eradication of T. solium infection is still unlikely in the near future. Major obstacles to practical implementation of control measures include low levels of sanitation and health education amongst endemic populations, ineffective health services infrastructure and inadequate socioeconomic development in these areas. The continued public health impact of neurocysticercosis, especially fatalities and epilepsy, force us to identify improved options for control. In order to implement control measures in highly endemic areas the active involvement of medical services in controlling T. solium infection and more effective collaboration between medical and veterinary services is necessary. A switch is suggested from total reliance on meat inspection to active diagnosis and treatment of human taeniasis, protection of pigs against infection, promotion of health education and improved surveillance preparing chemotherapeutic and/or sanitary interventions. This could be implemented in areas where active transmission causes substantial morbidity and mortality provided there is the political will, social support, better financing and an effective organizational framework.     

Expression of cell survival/death genes: Bcl-2 and Bax at the rate of colon cancer prognosis

The rate of tumour growth is dependent on the balance between proliferation and apoptosis at all stages of carcinogenesis. Apoptosis inhibition, in turn, depends partly on the balance between expression of two cell death regulatory genes, Bcl-2 and Bax. Colon cancer has long been associated with disturbances in apoptosis regulation. The aim of our study was to determine the expression levels of Bcl-2 and Bax mRNAs in 1 microg sample of total RNA obtained from normal colon and colon adenocarcinoma. This study was intended to evaluate possible differences in Bcl-2 and Bax mRNA levels at particular stages of colon adenocarcinoma classified according to Duke's system. The apoptotic frequency (represented by Bax mRNA copy number) was inversely proportional to the decrease of Bcl-2 gene expression. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) was performed to confirm apoptosis.     

Circular dichroism and aggregation studies of amyloid beta (11-8) fragment and its variants

Aggregation of Abeta peptides is a seminal event in Alzheimer's disease. Detailed understanding of Abeta assembly would facilitate the targeting and design of fibrillogenesis inhibitors. Here comparative conformational and aggregation studies using CD spectroscopy and thioflavine T fluorescence assay are presented. As a model peptide, the 11-28 fragment of Abeta was used. This model peptide is known to contain the core region responsible for Abeta aggregation. The structural and aggregational behaviour of the peptide was compared with the properties of its variants corresponding to natural, clinically relevant mutants at positions 21-23 (A21G, E22K, E22G, E22Q and D23N). In HFIP (hexafluoro-2-propanol), a strong alpha-helix inducer, the CD spectra revealed an unexpectedly high amount of beta-sheet conformation. The aggregation process of Abeta(11-28) variants provoked by water addition to HFIP was found to be consistent with a model of an alpha-helix-containing intermediate. The aggregation propensity of all Abeta(11-28) variants was also compared and discussed.