Obesity reduces the bioavailability of nitric oxide in juveniles

OBJECTIVE

There is growing evidence that nitric oxide (NO) is critically involved in obesity and its clinical consequences like cardiovascular disease, hypertension and diabetes. We hypothesize that NO is already involved in the pathophysiology of juvenile obesity. We here determined the role of NO, its metabolites arginine and citrulline in obese and normal weight children.

DESIGN

We investigated 57 obese and 57 normal weight age- and gender-matched juveniles. Various clinical parameters as well as body measurements and intima media thickness were determined.

RESULTS

Obese juveniles revealed highly significant alterations in the NO pathway. NOX and citrulline were decreased in obese compared to normal weight juveniles and negatively correlated with body weight. Arginine was increased in obese juveniles and positively correlated with body weight. We found a significant negative correlation between NOX and oxidized low-density lipoprotein. Analysis of gamma-aminobutyric acid (GABA) revealed correlations with the NO pathway as NOX and citrulline were negatively correlated with GABA and arginine showed a positive correlation.

CONCLUSION

We show here that NO and its metabolites arginine and citrulline are already involved in juvenile obesity that may contribute to atherogenesis via reduced bioavailability of NO. Moreover, we identify GABA as a new parameter in the mechanism of obesity-related NO reduction.

Compliance bei der Therapie schizophrener Patienten mit Neuroleptika - eine Übersicht

In connection with the efforts to improve the prophylaxis against relapse in schizophrenic patients, the topic of non-compliance to therapy with neuroleptics is gaining interest in scientific research. The importance of this problem has been underestimated in the past. Starting with a review of the current state of research, the article provides an overview of the various determinants of compliance. The conclusions made are discussed in terms of optimizing therapy possibilities. Central to this point are less psychopharmacological options but more process- related aspects of the doctor/patient relationship. Fully informed consent of the patient is aimed at; providing him with detailed information on the purposes and the side-effects of neuroleptic therapy is discussed in terms of its consequences regarding compliant behaviour.

IgG antibodies against food antigens are correlated with inflammation and intima media thickness in obese juveniles

OBJECTIVE

Systemic low grade inflammation may contribute to the development of obesity, insulin resistance, diabetes mellitus and atherosclerotic vascular disease. Food intolerance reflected by immunoglobulin G (IgG) antibodies may predispose to low grade inflammation and atherogenesis. We examined the relationship between IgG antibodies specific for food components, low grade inflammation and early atherosclerotic lesions in obese and normal weight juveniles.

RESEARCH METHODS AND PROCEDURES

We determined IgG antibodies directed against food antigens, C-reactive protein (CRP) and the thickness of the intima media layer (IMT) of the carotid arteries in 30 obese children and in 30 normal weight children.

RESULTS

Obese juveniles showed a highly significant increase in IMT (p=0.0001), elevated CRP values (p=0.0001) and anti-food IgG antibody concentrations (p=0.0001) compared to normal weight juveniles. Anti-food IgG showed tight correlations with CRP (p=0.001/r=0.546) and IMT (p=0.0001/r=0.513) and sustained highly significant in a multiple regression model.

DISCUSSION

We show here, that obese children have significantly higher IgG antibody values directed against food antigens than normal weight children. Anti- food IgG antibodies are tightly associated with low grade systemic inflammation and with the IMT of the common carotid arteries. These findings raise the possibility, that anti-food IgG is pathogenetically involved in the development of obesity and atherosclerosis.

Alkylcyanoacrylate nanocapsules prepared from mini-emulsions: a comparison with the conventional approach

Polyalkylcyanoacrylate nanocapsules are being prepared using two different types of o/w-emulsions: a conventional emulsion generated by intensive stirring with a home-made device and a mini-emulsion produced by the action of ultrasonic dispersion, using the alkylcyanoacrylate monomer as a hydrophobic agent. The emulsions and the resulting nanocapsule dispersions are compared using various methods of physical characterization. The formation of solid capsules is indicated by solid state NMR spectra and atomic force microscopy. Differences between the results of both synthetic approaches are found in terms of particle size distribution, zeta potential and tendency towards particle agglomeration. Capsules prepared by ultrasound via the mini-emulsion pathway tend to be smaller and more monodisperse. Their zeta potential is negative with larger absolute values as compared to capsules obtained from conventional emulsions, leading to stronger repulsive interactions and a higher stability against capsule agglomeration.

Activation of protein kinase Cepsilon stimulates DNA-repair via epidermal growth factor receptor nuclear accumulation

PURPOSE

To elucidate the interaction between radioprotector O-phospho-l-tyrosine (P-Tyr) with epidermal growth factor receptor (EGFR).

METHODS

Molecular effects of P-Tyr at the level of EGFR responses were investigated in vitro with TP53-wildtype bronchial carcinoma cell line A549, which is radio-protected by P-Tyr treatment. Nuclear EGFR accumulation was followed by confocal microscopy and Western blotting. PKCepsilon protein expression was impaired by specific siRNA. Residual DNA-damage was quantified with gammaH(2)AX foci analysis.

RESULTS

P-Tyr mediated radio-protection was associated with nuclear EGFR accumulation. Radiation-induced nuclear EGFR presented increased phosphorylation at residue No. T654. We identified PKCepsilon as responsible for T654-phosphorylation. Knockdown of PKCepsilon by siRNA blocked both radiation- and P-Tyr-triggered nuclear EGFR accumulation. Furthermore, nuclear accumulation of EGFR was associated with increased phosphorylation of DNA-dependent protein kinase (DNA-PK) at residue No. T2609, essential for DNA-repair. Consequently P-Tyr mediated effects upon DNA-PK resulted in a significant reduction of radiation-induced residual gammaH(2)AX-foci. Knockdown of PKCepsilon increased radiation-induced residual damage and abolished the P-Tyr associated radioprotection. In addition, P-Tyr mediated radioprotection was completely absent in colony formation assay.

CONCLUSION

The data presented herein suggest that P-Tyr-treatment mediates activation of PKCepsilon, which triggers nuclear EGFR accumulation. Nuclear EGFR is involved in phosphorylation of DNA-PK at Thr2609, which has a significant impact upon DNA-DSB repair.

Celecoxib induced tumor cell radiosensitization by inhibiting radiation induced nuclear EGFR transport and DNA-repair: a COX-2 independent mechanism

PURPOSE

The purpose of the study was to elucidate the molecular mechanisms mediating radiosensitization of human tumor cells by the selective cyclooxygenase (COX)-2 inhibitor celecoxib.

METHODS AND MATERIALS

Experiments were performed using bronchial carcinoma cells A549, transformed fibroblasts HH4dd, the FaDu head-and-neck tumor cells, the colon carcinoma cells HCT116, and normal fibroblasts HSF7. Effects of celecoxib treatment were assessed by clonogenic cell survival, Western analysis, and quantification of residual DNA damage by gammaH(2)AX foci assay.

RESULTS

Celecoxib treatment resulted in a pronounced radiosensitization of A549, HCT116, and HSF7 cells, whereas FaDu and HH4dd cells were not radiosensitized. The observed radiosensitization could neither be correlated with basal COX-2 expression pattern nor with basal production of prostaglandin E2, but was depended on the ability of celecoxib to inhibit basal and radiation-induced nuclear transport of epidermal growth factor receptor (EGFR). The nuclear EGFR transport was strongly inhibited in A549-, HSF7-, and COX-2-deficient HCT116 cells, which were radiosensitized, but not in FaDu and HH4dd cells, which resisted celecoxib-induced radiosensitization. Celecoxib inhibited radiation-induced DNA-PK activation in A549, HSF7, and HCT116 cells, but not in FaDu and HH4dd cells. Consequentially, celecoxib increased residual gammaH2AX foci after irradiation, demonstrating that inhibition of DNA repair has occurred in responsive A549, HCT116, and HSF7 cells only.

CONCLUSIONS

Celecoxib enhanced radiosensitivity by inhibition of EGFR-mediated mechanisms of radioresistance, a signaling that was independent of COX-2 activity. This novel observation may have therapeutic implications such that COX-2 inhibitors may improve therapeutic efficacy of radiation even in patients whose tumor radioresistance is not dependent on COX-2.

The radioprotector O-phospho-tyrosine stimulates DNA-repair via epidermal growth factor receptor- and DNA-dependent kinase phosphorylation

BACKGROUND AND PURPOSE

Purpose of the study was to elucidate the underlying molecular mechanism of the radioprotector O-phospho-tyrosine (P-Tyr).

METHODS

Molecular effects of P-Tyr at the level of EGFR responses were investigated in vitro with bronchial carcinoma cell line A549. Nuclear EGFR transport and DNA-PK activation were quantified after Western blotting. Residual DNA-damages were quantified by help of gammaH(2)AX focus assay.

RESULTS

As determined by dose-response curves, treatment of cells with P-Tyr for 16h before irradiation results in radioprotection. Simultaneous treatment with EGFR blocking antibody Cetuximab abolished P-Tyr associated radioprotection. At the molecular level P-Tyr mediated a general phosphorylation of EGFR and a pronounced phosphorylation of nuclear EGFR at residue Thr No. 654, also observed after treatment with ionizing radiation. This phosphorylation was associated with nuclear EGFR accumulation. Moreover, P-Tyr-triggered EGFR nuclear accumulation was associated with phosphorylation of DNA-PK at Thr 2609. This activated form of DNA-PK was not DNA associated, but after radiation, DNA binding increased, particularly after P-Tyr pre-treatment. These molecular effects of P-Tyr resulted in a reduction of residual DNA-damage after irradiation.

CONCLUSIONS

Radioprotection by P-Tyr is mediated through its stimulation of nuclear EGFR transport and concurrent, but DNA-damage independent, activation of DNA-PK. Thus, subsequent irradiation results in increased binding of DNA-PK to DNA, improved DNA-repair and increased cell survival.

Mononuclear cell metallothionein mRNA levels in human subjects with poor zinc nutrition

Human zinc deficiency is thought to be prevalent worldwide, particularly in populations with diets low in zinc and animal protein and high in inhibitors of zinc absorption, such as phytic acid. Confirmation of zinc deficiency is, however, difficult in the absence of a reliable and sensitive marker of zinc status. Under controlled conditions, T-lymphocyte metallothionein-2A (MT-2A) mRNA levels change in relation to zinc status and the objective of the present study was to investigate whether these transcript levels could be related to dietary zinc intake, plasma zinc or other biochemical parameters influenced by, or influencing, zinc metabolism in human subjects likely to be zinc deficient. Rural Koreans (n 110, age 50-80 years) with a range of zinc and phytic acid dietary intake were recruited for the study and blood samples were analysed for plasma zinc, HDL, LDL, alpha-tocopherol and thiobarbituric acid reactive substances, mononuclear cell (MNC) MT-2A mRNA, serum protein and albumin, and blood haematocrit, Hb and glucose. Multiple correlation and principal component analysis showed a significant negative correlation between plasma zinc and MNC MT-2A mRNA levels. Female subjects had higher MT-2A transcript levels than males and MT-2A mRNA levels tended to increase with age. There was no significant association between dietary zinc intake or any index of zinc intake relating to dietary inhibitors of zinc absorption. It is concluded that MNC MT-2A mRNA levels cannot be used to predict poor zinc nutrition.

Rosuvastatin reduces interleukin-6-induced expression of C-reactive protein in human hepatocytes in a STAT3- and C/EBP- dependent fashion

OBJECTIVE

It has been speculated that the reduction in vascular events by statins may not only be due to lowering of cholesterol, but also to the decrease in plasma C-reactive protein (CRP). In the present study we investigated the possibility that rosuvastatin directly affected CRP expression in stimulated human hepatocytes.

METHODS

Interleukin 6 (IL-6) stimulated human hepatoma cells (Hep3B) and primary human hepatocytes (PHH) were incubated with various concentrations of rosuvastatin (0.3 - 1 microM) for 24 hours. CRP expression was determined using ELISA and quantitative real-time RT-PCR. The activation of STAT3 and C/EBP was investigated utilizing transcription factor assays (TransAM).

RESULTS

IL-6 increased CRP secretion by up to 5-fold in Hep3B and 6.6-fold in PHH. Rosuvastatin reduced CRP expression by 32% and 46% in Hep3B and PHH, respectively. IL-6 increased CRP mRNA up to 32-fold. At 1 microM, rosuvastatin reduced CRP mRNA by 73% compared to IL-6-stimulated cells. IL-6 activated the transcription factors STAT3 and C/EBP up to 2.6-fold and 2.2-fold, respectively. Rosuvastatin (1 microM) attenuated the activation of STAT3 and C/EBP by 48% and 54%, respectively.

CONCLUSIONS

Our results show a direct inhibitory effect of rosuvastatin on IL-6-induced expression of CRP in liver cells. Statins may lower CRP by inhibiting its production in the liver rather than by exerting systemic anti-inflammatory effects. The effects of rosuvastatin in reducing the levels of CRP in plasma may have clinical utility in addition to its effects on atherogenic lipoproteins.

Assessing cubicle dimensions for finishing bulls based on animal behaviour and cleanliness

Finishing bulls need increasingly large cubicles throughout their growth, and optimal cubicle dimensions may differ from those used for dairy cows. The space requirements of finishing bulls was investigated by observing standing-up and lying-down behaviour, lying duration and number of lying bouts, as well as the cleanliness of cubicles and animals before and after increasing cubicle size at four different points in time. Lying area in the cubicles measured 120 × 70 cm at the start and 185 × 110 cm at the end of the finishing period (approx. at 160 and 550 kg, respectively). Twenty animals kept in four groups were observed at weights of approximately 220, 330, 380 and 500 kg before and after cubicle dimensions were increased. The proportion of standing-up events with more than one head lunge decreased with enlargement of the cubicles (P = 0·01). As cubicle size increased, bulls hit the partition rails less on standing up, except at 220 kg weight where the pattern was inverted (interaction: P = 0·001). Partitions were also hit less on lying down as cubicle size increased, except at 220 kg weight with an inverse pattern (interaction: P = 0·01). The number of exploratory head sweeps before lying down did not change with cubicle enlargement (P > 0·5). Bulls slipped more often with cubicle enlargement, except at 380 kg where the difference was inverted (interaction: P = 0·03). They never fell and never turned around in the cubicles. In general, both animals and cubicles were very clean. On average, lying duration decreased (P < 0·01) while the number of lying bouts tended to increase (P = 0·052) with enlargement of the cubicles but the absolute differences were small. Consequently at each point in time, the smaller cubicles still seemed to provide sufficient lying space for the bulls. If the impacts with the partitions were minor and did not represent a serious welfare concern, as suggested by qualitative observations, the cubicle dimensions used could be considered suitable for housing the type of finishing bulls used in this study.

Effects of two weeks' mandatory snack consumption on energy intake and energy balance

OBJECTIVE

Our goal was to compare the effects of mandatory consumption of commercial snack products (CSPs) on energy intakes and energy balance in free-living adults and to assess the interaction between habitual level of CSP consumption and the interventions.

RESEARCH METHODS AND PROCEDURES

Four groups of 18 subjects (lean and overweight, males and females) were studied using a crossover design. Subjects consumed one type of CSP (high-carbohydrate, high-fat, or mixed composition) at three manipulations of energy 0 MJ (control), 1.5 MJ (low-energy), and 3.0 MJ (high-energy) each day during three 14-day interventions. The study design was parallel for type of CSP (macronutrient composition) and within-subjects for energy level. Subjects self-recorded food intakes between Days 8 and 14, and body weights were investigator-recorded on Days 1, 8, and 15 of each intervention period. Daily energy expenditure was estimated by heart rate monitoring.

RESULTS

Daily energy intakes increased from 10.4 MJ (control) to 11.1 MJ (low-energy) and 11.5 MJ (high-energy) (p < 0.001), resulting in a trend (not significant) for body weight gain. Energy balance was more positive when subjects were not recording their food intakes than when they were (p < 0.001). There was a trend (not significant) for greater increases in energy intake with increasing fat content, and energy density, of the interventions. Frequent CSP consumers compensated more for the interventions than did infrequent CSP consumers (R2 = 0.125, p = 0.003).

DISCUSSION

Subjects partially compensated for energy when supplemented with CSPs over 14-day periods, although this was insufficient to prevent some increase in energy balance. The level of compensation correlated with habitual energy intake from CSPs.

Altered expression of SOCS3 in the hypothalamic arcuate nucleus during seasonal body mass changes in the field vole, Microtus agrestis

We have previously shown that cold-acclimated (8 degrees C) male field voles (Microtus agrestis) transferred from short day (SD, 8 h light) to long day (LD, 16 h light) photoperiod exhibit an increase in body mass lasting 4 weeks, after which they stabilise at a new plateau approximately 7.5 g (24.8%) higher than animals maintained in SD. By infusing voles with exogenous leptin, we have also demonstrated that SD voles respond to the hormone by reducing body mass and food intake, whereas LD animals increasing body mass are resistant to leptin treatment. In the present study, we investigated whether seasonal changes in body mass could be linked to modulation of the leptin signal by suppressor of cytokine signalling-3 (SOCS3). We used in situ hybridisation to examine hypothalamic arcuate nucleus (ARC) expression of SOCS3, neuropeptide Y (NPY), agouti-related peptide (AgRP), pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) genes in 90 voles exposed to either SD or LD for up to 11 weeks. LD voles increasing body mass had significantly higher levels of SOCS3 mRNA than SD or LD voles with a stable body mass. There were no associated changes in expression of NPY, AgRP, POMC and CART genes. These results suggest that voles that regulate body mass at either the lower (SD) or upper (LD) plateau remain sensitive to leptin action, whereas SOCS3-mediated leptin resistance is a short-term mechanism that enables animals to move between the stable body mass plateaus. Our data provide evidence that expression of SOCS3 in the ARC is involved in the modulation of the strength of the leptin signal to facilitate seasonal cycles in body mass and adiposity.

Ribosome biogenesis and cell growth: mTOR coordinates transcription by all three classes of nuclear RNA polymerases

The target of rapamycin (TOR) signal-transduction pathway is an important mechanism by which eucaryotic cells adjust their protein biosynthetic capacity to nutrient availability. Both in yeast and in mammals, the TOR pathway regulates the synthesis of ribosomal components, including transcription and processing of pre-rRNA, expression of ribosomal proteins and the synthesis of 5S rRNA. Expression of the genes encoding the numerous constituents of ribosomes requires transcription by all three classes of nuclear RNA polymerases. In this review, we summarize recent advances in understanding the interplay among nutrient availability, transcriptional control and ribosome biogenesis. We focus on transcription in response to nutrients, detailing the relevant downstream targets of TOR in yeast and mammals. The critical role of TOR in linking environmental queues to ribosome biogenesis provides an efficient means by which cells alter their overall protein biosynthetic capacity.

Universal childhood immunisation with pneumococcal vaccine and meningococcal serogroup C vaccine introduced in Germany

In July 2006, vaccination against meningococcal C and pneumococcal disease was added to the routine childhood immunisation programme in Germany

Leg lesions and cleanliness of finishing bulls kept in housing systems with different lying area surfaces

The influence of the quality of different lying surfaces on lesions and swellings at the joints as well as on the cleanliness of finishing bulls throughout the fattening period was studied. On 17 farms (623 bulls), pens with fully slatted concrete floors (CONCRETE), with rubber coated slats (RUBBER), with cubicles (CUBICLES, provided with five different types of soft lying mat) and with a littered lying area (STRAW) were compared. Bulls kept on STRAW developed the smallest lesion scores at the joints. In CUBICLES, there was a huge variability in the lesion scores depending on the type of lying mat, ranging from values comparable to STRAW up to and greater than the values for CONCRETE. The highest lesion scores at the carpal joints were found on CONCRETE, with intermediate values on RUBBER and in CUBICLES. At the tarsal joints, lesion scores were similar on CONCRETE and RUBBER and in the same range or worse on most mats in the CUBICLES. Swelling scores were highest on CONCRETE and intermediate on RUBBER and in CUBICLES compared to STRAW. In general, there was a steady increase in the lesion scores of the leg joints throughout the fattening period on CONCRETE, RUBBER and STRAW, whereas on some of the mats in CUBICLES these scores were at a high level from early on in the fattening period. Animals in all the housing systems were clean over the whole fattening period. Littering the lying area in CUBICLES affected neither the lesion scores nor the swelling scores at the joints nor animal cleanliness. In conclusion, both rubber coated slats and cubicles provided with soft lying mats were favourable with regard to the levels of lesions and swellings of the leg joints of finishing bulls compared to concrete slats. However, these levels were even lower in pens with a straw bedded lying area.

Sequence characterization and expression patterns of defensin and lysozyme encoding genes from the gut of the reduviid bug Triatoma brasiliensis

The cDNAs encoding an intestinal defensin (def1) and lysozyme (lys1) of the reduviid bug Triatoma brasiliensis have been amplified by PCR using specific oligonucleotide primers and 5'- and 3'-RACE, cloned and sequenced. The 576 bp clone has an open reading frame of 282 bp and encodes a pre-prodefensin with 94 amino acid residues, containing a putative signal and activation peptide cleavage site at Ser19 and Arg51, respectively. The genomic DNA contains a second defensin gene with similar characteristics, 88.3% identity and also one intron of 107 nucleotides. The 538 bp clone has an open reading frame of 417 bp, encoding a pre-lysozyme with 139 amino acid residues. The putative signal peptide is cleaved at alanine 18. Using whole mount in situ hybridization, high expression of both genes has been found, distributed uniformly throughout the entire cardia and the blood-storing stomach and to a much lower extent in the digesting small intestine. Using quantitative real-time PCR, the expression level of def1 was also shown to be very low in small intestine, rectum and salivary glands; in the stomach, expression was 500-2500 times higher than in the cardia and fat body. No expression of lys1 could be detected in the salivary glands and rarely a very low expression in the small intestine, rectum and fat body. Lys1 expression in the stomach was 60-300 times higher than in the cardia. Comparing the levels in unfed fifth instars and up to 15 days after feeding, a strong def1 induction was evident in the fat body at 15 days after feeding and in the stomach a maximum level of def1 and lys1 at 5 days after feeding.

Effects of added fruits and vegetables on dietary intakes and body weight in Scottish adults

An increased consumption of fruits and vegetables (F&V) has been suggested as a way to limit, or even lower, energy and fat intakes. The present study examined the effects of incorporating F&V supplements into the diets of adults who reported consuming <240 g (three portions) of F&V per d on energy and fat intakes, and change in body weight, over 8 weeks using a randomised parallel design. Thirty-four males and twenty-eight females (age 42.6 (sd 11.1) years, BMI 23.7 (sd 2.7) kg/m(2)) were each provided with supplements of 0, 300 or 600 g F&V per d. Food, nutrient and energy intakes were measured before, during and at the end of the supplementation period using 7 d weighed records. Mean daily energy intakes were not different among the three groups before (P = 0.151) or during the supplementation periods (P = 0.407), although changes in energy intakes over the study period tended to be more positive with increasing amounts of F&V supplements (P = 0.078). There was no difference in changes of body weights during the study (P = 0.242). Carbohydrate (P < 0.001), sugar (P < 0.001), fibre (P < 0.001) and weight of food consumed (P = 0.022) increased in the treatment groups. There were no significant differences, or changes, in fat intakes among the three groups. Consumption of mandatory F&V supplements for 8 weeks produced beneficial changes in diet composition, but did not result in lower reported energy or fat intakes, and did not result in loss of body weight.

Nanocapsules as drug delivery systems

Dispersed polymer nanocapsules can serve as nano-sized drug carriers to achieve controlled release as well as efficient drug targeting. The dispersion stability and the primary physiological response are mainly determined by the type of the surfactant and the nature of the outer coating. Their release and degradation properties largely depend on the composition and the structure of the capsule walls. Another important criterion is the capsule size, where an optimum is generally seen for radii ranging between 100 and 500 nm. Nanocapsules can be prepared by four principally different approaches: interfacial polymerization, interfacial precipitation, interfacial deposition, and self assembly procedures. All these procedures offer their individual advantages and disadvantages when it comes to the design of optimized drug carrier systems. The most important capsule parameters such as capsule radius distribution, the capsule surface, the thickness and the permeability of the capsule membrane and its thermal or chemical decomposition, are discussed and examples are shown. In combination with efficient preparation procedures, nanocapsule dispersions allow for new and promising approaches in many kinds of pharmaceutical therapies.

Renale Anämie — eine wichtige Folgeerkrankung der Niereninsuffizienz

Anemia is as a frequent complication in patients with chronic kidney disease, which gains in importance in the treatment of patients with renal disease. The main cause of renal anemia is the inadequately low production of endogenous erythropoietin. Often the patients develop an additional absolute or functional iron deficiency, which complicates the diagnostic and therapeutic procedures. Substitution of recombinant human erythropoietin (r-HuEPO) is the most effective therapy. The goal is a stable haemoglobin level >11 g/dl. An often additional existing iron deficiency should be balanced adequately according to the guidelines. With consequent and early treatment morbidity, mortality, and quality of life can be effectively improved.

Inhibition of radiation-induced EGFR nuclear import by C225 (Cetuximab) suppresses DNA-PK activity

BACKGROUND AND PURPOSE

Inhibition of EGFR-function can induce radiosensitization in tumor cells. Purpose of our investigation was to identify the possible molecular mechanism of radiosensitization following treatment with anti-EGFR-antibody C225 (Cetuximab).

MATERIALS AND METHODS

The effect of C225 on radiation response was determined in human cell lines of bronchial carcinoma (A549) and breast adenoma cells (MDA MB 231). The molecular effects of C225 on EGFR-function after irradiation were analyzed applying western blotting, immune-precipitation and kinase assays. Effects on DNA-repair were detected by quantification of gamma-H2AX positive foci 24h after irradiation.

RESULTS

The EGFR specific antibody C225 induced radiosensitization in A549 and also in MDA MB 231 cells. Radiosensitization in A549 was associated with blockage of radiation-induced EGFR transport into the nucleus, and immobilized the complex of EGFR with DNA-dependent protein kinase (DNA-PK) in the cytoplasm. As a consequence radiation-induced DNA-PK activation was abolished, a process that is essential for DNA-repair after radiation exposure. Likewise C225 treatment increased the residual amount of gamma-H2AX-positive foci 24h after irradiation in A549 and in MDA MB 231 cells.

CONCLUSIONS

Our results suggest that irradiation induced DNA-PK activation-essential for DNA repair-may be hampered specifically by use of the anti-EGFR-antibody C225. This process is associated with radiosensitization.

NMR-Characterization of Magnetic Fluids

31P-NMR spectra have been measured on aqueous solutions and gels of phosphorylated polyvinyl alcohol in absence and in presence of dispersed magnetic nanoparticles. In this system, the rotational diffusion is still rapid enough for a sufficient averaging of the CSA tensor of the 31P nucleus. At the same time, the lateral diffusion of the 31P nuclei is significantly reduced. Under these circumstances, it is possible to detect the spatial distribution of the local field by 31P-NMR. The obtained line shape exhibits the characteristic shark fin pattern which has been predicted on a theoretical basis. This basically supports the proposed dependence of the NMR line shape on the velocity of lateral diffusion which allows for detailed analysis of lateral motion.