Dose-dependent biphasic induction and transcriptional activity of nuclear factor kappa B (NF-kappaB) in EA.hy.926 endothelial cells after low-dose X-irradiation

PURPOSE

Low-dose radiotherapy is known to exert an anti-inflammatory effect, but the underlying radiobiological mechanisms are still elusive. It was recently reported that transforming growth factor (TGF) beta1 essentially contributes to the reduced adhesion of peripheral blood mononuclear cells to endothelial cells at low-dose X-irradiation. As the transcription factor nuclear factor kappa B (NF-kappaB) is crucially involved in mediating an inflammatory response by inducing the expression of cytokines and adhesion molecules, NF-kappaB DNA binding and transcriptional activity as well as its impact on the expression of TGF-beta1 in EA.hy.926 endothelial cells were analysed subsequently to low-dose radiotherapy.

MATERIALS AND METHODS

Human EA.hy.926 endothelial cells were grown to subconfluence. Twenty hours after X-irradiation with single doses ranging from 0.3 to 3 Gy, the cells were activated with tumour necrosis factor-alpha. Four hours later, the cells were harvested. NF-kappaB DNA-binding activity of nuclear extracts was analysed by electrophoretic mobility shift assay. The NF-kappaB subunits p50, p65/RelA, c-Rel and RelB of the NF-kappaB complexes were quantified by enzyme-linked immunoabsorbant assay. The transcriptional activity of NF-kappaB was measured using luciferase reporter gene assays in EA.hy.926 endothelial cells transiently transfected with the plasmid pB2xLuc. To correlate transcriptional activity to TGF-beta1 expression, NF-kappaB decoy oligonucleotides were used to inhibit NF-kappaB activity and TGF-beta1 secretion.

RESULTS

After low-dose radiotherapy, an increased NF-kappaB DNA-binding activity was observed in stimulated EA.hy.926 endothelial cells with a relative maximum (threefold induction) at 0.5 Gy. The NF-kappaB activation then decreased after X-irradiation at 0.6-0.8 Gy and subsequently increased again at doses of 1 and 3 Gy. This biphasic induction profile of NF-kappaB was confirmed by the analysis of the NF-kappaB-specific transcriptional activity. The latter showed a relative maximum at 0.5 Gy, a relative minimum between 0.5 and 1.0 Gy, and an increase at 3 Gy. Transfection of EA.hy.926 endothelial cells with NF-kappaB decoy oligonucleotides before irradiation resulted in a 50% reduction of TGF-beta1 secretion at 0.5 Gy compared with control oligonucleotides or untreated cells.

CONCLUSIONS

Low-dose radiotherapy induces a biphasic activation of NF-kappaB with a relative maximum at 0.5 Gy. The induction by NF-kappaB of TGF-beta1 in endothelial cells might contribute to the anti-inflammatory properties of low-dose ionizing irradiation.

[Predictive microbiology and risk assessment]

Predictive microbiology (predictive modelling PM), in spite of its limits and short-comings, may often contribute to a reduction of the problems arising when HACCP systems are established or microbiological risk assessment is done. Having identified the agents which constitute a risk and the contamination rate and density in the raw material, the influences of production steps and storage on these microorganisms have to be examined. Finally, there should be an exposure assessment, i.e. an estimate of the contamination density in the final product at the time of consumption. Should the exposure assessment together with data from dose response assessments reveal a potential for intake of inacceptable numbers of organisms, the risk identified has to be characterized. As a consequence, risk management should result in a modification of the composition of the product and/or of the production process so that the risk does not surpass an acceptable limit. For this approach it is indispensable to have product- and process-specific information on the multiplication of pathogens prior to heat treatment, on reduction of their density by thermal treatment and on growth or dying of organisms having survived heat treatment or penetrated into the product after heat treatment as post-process contaminant. Commonly, challenge tests are conducted to provide such information. But they are time consuming and, as their results are only valid for the specific product tested and the conditions prevailing during the experiment, the have to be repeated if there is any modification of intrinsic or extrinsic factors. At least partially, the PM may replace the challenge tests. The efficiency of the models is rated particularly high if they are used already at the stage of product development when the question has to be answered whether a planned recipe or process of production are already save or have to be modified to become save.

Hypothalamic neuropeptide release after experimental subarachnoid hemorrhage: in vivo microdialysis study

OBJECTIVES

As evidence exists about independent regulation of peripheral and central release of the vasoactive and natriuretic neuropeptides arginine-vasopressin (AVP) and oxytocin (OXT), we investigated their release patterns following subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

After injection of 0.1 ml arterial blood or saline into the great cistern of 33 Wistar rats, AVP and OXT levels were measured in blood and by microdialysis in the hypothalamic supraoptic (SON) and paraventricular nucleus (PVN). For statistical analysis, the analysis of variance (ANOVA) was used with Tukey HSD post hoc ANOVA tests to determine specific group differences.

RESULTS

Plasma AVP and OXT peaked 2 h after SAH (P < 0.05), and normalized at 4 h. In the SON, both AVP and OXT peaked 4 h after SAH (P < 0.05). In the PVN, AVP increased in both groups (P < 0.05), while no OXT release occurred. By the sham group, any effect of experimental procedure was excluded.

CONCLUSIONS

The SAH-specific central neuropeptide release, which exceeded peripheral release and continued longer, may contribute to pathophysiological events following SAH.

Autonomous nervous system with respect to dressing of cattle carcasses and its probable role in transfer of PrP(res) molecules

Pathogen prions are widely recognized as the causative agent in bovine spongiform encephalopathy (BSE) and other transmissible spongiform encephalopathies. However, more research on the possible transmission mutes of this agent once it has reached the host is needed. There is evidence based on the anatomy and physiology of the autonomous nervous system (ANS), as well as observations for different animal species, that the ANS might be involved in the axonal drainage of pathogen prions toward the central nervous system. In this context, more attention should be paid to the cranial cervical ganglion, the stellate ganglion, the chain of paravertebral ganglia next to the first six thoracic vertebrae, the chain of the paravertebral ganglia next to loin vertebrae 1 through 6, the vagus nerve in the neck region and in the mediastine, and the esophagus (because of its close connection to the vagus nerve). For a more detailed risk analysis with respect to these tissues, the ANSs of animals having shown clinical signs of BSE might be examined to corroborate the evidence presented here. In the meantime, as a precautionary measure, the tissue addressed should be taken out of the human food chain, taken out of animal feed, and handled as if it were specified risk material. It is technically possible to remove these parts during cutting and dressing.

Anti-inflammatory effect of low-dose X-irradiation and the involvement of a TGF-beta1-induced down-regulation of leukocyte/endothelial cell adhesion

PURPOSE

Low-dose radiotherapy (LD-RT) is known to exert an anti-inflammatory effect, but the underlying radiobiological and immunological mechanisms remain elusive. In recent studies, we observed a reduced adhesion of peripheral blood mononuclear cells (PBMC) to endothelial cells (EC) after LD-RT (0.3-0.7 Gy). This shows that this treatment affects the initial steps of the inflammatory response. To explore the role of inflammatory mediators in this process, we investigated the expression of Transforming growth factor beta(1) (TGF-beta(1)) and Interleukin 6 (IL-6) after LD-RT.

MATERIALS AND METHODS

EC were grown to subconfluence and irradiated with single-dose LD-RT. Twenty-hours after irradiation, EC were treated with IL-1beta for 4 h and then incubated with peripheral blood mononuclear cells (PBMC). Adherent PBMC were counted when using light microscopy. Expression of the cytokines TGF-beta(1) and IL-6 was measured by ELISA, and mRNA levels were analysed by the RNAse-protection assay (RPA). Surface expression of E-selectin was quantified by flow cytometry.

RESULTS

A relative minimum of adhesion was observed after LD-RT between 0.3 and 0.7 Gy. This was paralleled by an expression maximum of TGF-beta(1) and IL-6, as shown by protein and mRNA levels, respectively. Neutralization of TGF-beta(1) by monoclonal antibodies, but not of IL-6, increased PBMC adhesion to EC nearly to control levels. In addition, fluorescence activated cell sorter (FACS) analysis of irradiated EC demonstrated a down-regulation of E-selectin in the same dose range.

CONCLUSION

Low-dose X-irradiation between 0.3 and 0.7 Gy induced a relative maximum of TGF-beta(1) production by stimulated EC. This results in a down-regulation of leukocyte/PBMC adhesion and may contribute to the anti-inflammatory effect of LD-RT.

The Thy-1/Thy-1 ligand interaction is involved in binding of melanoma cells to activated Thy-1- positive microvascular endothelial cells

The expression of adhesion molecules on endothelial cells as well on tumor cells regulates and directs adhesion and transmigration of tumor cells through the endothelial cell barrier as one prerequisite to the formation of metastasis. Thy-1 is an inducible activation-associated cell-adhesion molecule on human dermal microvascular endothelial cells (HDMECs). In this study we investigated whether the Thy-1/Thy-1 ligand interaction may also play a role in adhesion of melanoma cells to endothelial cells. In situ, a strong Thy-1 expression on endothelial cells in melanoma and melanoma metastases was observed. In vitro, Thy-1 expression was stimulated by melanoma-cell-derived soluble factors, reflecting that Thy-1 expression in melanoma is not only due to a nonspecific inflammatory response. TNFalpha and bFGF were not responsible for this effect. In vitro and in situ a Thy-1 ligand was detected on melanoma cells. In cell-adhesion assays we showed the involvement of the Thy-1/Thy-1 ligand interaction in adhesion of melanoma cells to HDMECs. In summary, the data support that the study of the Thy-1/Thy-1 ligand interaction might give a more detailed insight into the regulation and direction of adhesion of melanoma cells to endothelial cells as one critical step in the formation of tumor metastasis.

Mononuclear cell adhesion and cell adhesion molecule liberation after X-irradiation of activated endothelial cells in vitro

PURPOSE

Increased expression of cell adhesion molecules on endothelial cells is an important early event in inflammation. Low-dose radiotherapy is very effective anti-inflammatory treatment. The hypothesis that it may act by modulation of cell adhesion molecule expression in activated endothelial cells and the subsequent adhesion of mononuclear cells onto the activated endothelial cells was tested.

MATERIALS AND METHODS

EA.hy.926 endothelial cells were irradiated with 0.3-10 Gy X-rays at different times before or after stimulation with TNFalpha. ICAM-1 or E-selectin expression was measured by ELISA and FACS. Isolated peripheral blood mononuclear cells were incubated with an activated and irradiated confluent monolayer of endothelial cells 4 h, 12 h or 24 h after stimulation, and adhesion was determined in dynamic and static adhesion assays.

RESULTS

In the static adhesion assay, where integrin-mediated adhesion dominates, radiation doses of 0.3-0.6 Gy reduced the adhesion of mononuclear cells onto EA.hy.926-EC in vitro by 25-40% and 15-25% of the control level 4 h and 24 h after stimulation, respectively, but increased adhesion 12 h after stimulation. In the dynamic adhesion assay, where selectin-mediated adhesion dominates, radiation doses of 0.3-0.6 Gy reduced the adhesion events by 40-50% and 30-40% of the control level 4 h and 24 h after stimulation, respectively, and again increased adhesion 12h after stimulation. X-ray doses of < or =5 Gy did not induce ICAM-1 expression, or modulate TNFalpha-induced ICAM-1 expression. E-selectin expression was, however, increased in a dose-dependent way 6 h after irradiation. In contrast, X-irradiation 2-5 h before stimulation decreased the characteristic transient expression of E-selectin after TNFalpha stimulation.

CONCLUSIONS

Modulation of E-selectin liberation on activated endothelial cells may be one mechanism to decrease leukocyte adhesion after low-dose irradiation in vitro, and could be involved in the therapeutic action of anti-inflammatory radiotherapy.

Fibroblasts enhance the invasive capacity of melanoma cells in vitro

In previous experiments we have shown an enhanced expression of matrix metalloproteinase-1 (MMP-1) in fibroblasts obtained from the border of invasive melanoma in comparison to fibroblasts more distant from the tumour. In the study reported here we sought to determine whether melanoma-derived soluble factors are responsible for the stimulation of MMP-1 expression in fibroblasts. By real-time PCR and enzyme-linked immunosorbent assays, we demonstrated that the stimulation of fibroblasts with melanoma cell conditioned medium led to an increased expression of MMP-1 mRNA as well as MMP-1 protein, whereas melanoma cells themselves did not produce detectable amounts of MMP-1 protein. Basic fibroblast growth factor (bFGF) was detected as an important factor responsible for the enhanced expression of MMP-1 by fibroblasts after stimulation with melanoma cell conditioned medium. In a three-dimensional in vitro invasion assay, we demonstrated that fibroblasts are essential for melanoma cell invasion into a collagen I matrix. These findings support the hypothesis that stromal fibroblasts assist the invasion of melanoma cells through the extracellular matrix by producing elevated amounts of proteolytic enzymes after interaction with soluble factors (e.g. bFGF).

Use of transcranial duplex sonography in the treatment of intracranial aneurysms

The use of transcranial duplex sonography in documenting additional findings by measuring vasospasm and visualising aneurysms in neurosurgical patients is described. Daily measurement of vasospasm using this method enables reassessment of the status of the lesion in the context of the patient's clinical condition. This offers a practical alternative to angiographic investigation in aneurysm patients, provided ultrasound penetration of the cranium is optimal.

Cutaneous breast angiosarcoma after conserving treatment of breast cancer

Cutaneous angiosarcoma is a rare malignancy that sometimes occurs as a late sequela of breast conservation therapy. We report on a 79-year-old female who developed well-differentiated angiosarcoma in a lymphedematous left breast 5.5 years after surgery and radiotherapy for early invasive ductal breast cancer. The initial appearance was very similar to late radiation dermatitis, and histologically interpreted as scar tissue with atypical vascular lesion. The lesion progressed further, and was clinically suspicious for angiosarcoma. Thus, a second biopsy was taken which confirmed the diagnosis. A complete mastectomy removed all the tumor with clear margins. However, within a period of 16 months she presented four local recurrences which were treated by wide local excision. At present, the patient is free of locally recurrent tumour for 7 months. The few cases of breast angiosarcoma after breast conservation therapy reported so far demonstrate that these lesions are difficult to diagnose due to their rarity and their highly variable and benign appearance, which sometimes may mimic radiation-induced cutaneous changes. Since chronic lymphedema possibly contributes to the development of angiosarcoma, long-term clinical surveillance of these patients is recommended. Biopsies should be taken if new skin lesions occur.

[Comparison of direct colony count methods and the MPN-method for quantitative detection of Listeria in model and field conditions]

In order to compare the plate count method for quantitating Listeria, as published in the "Official Collection of Testing Methods" in section 35 LMBG (L. 00.00-22), to an MPN-method for Listeria based on the same mediums, these two detection methods for Listeria were tested in three sets of experiments and a routine sample status evaluation. A pure broth culture of L. monocytogenes, artificially with L. monocytogenes contaminated ground meat, artificially contaminated and cold stored ground meat as well as 77 ground beef samples from Berlin retail food stores were used in the four trials. The detection limit of the MPN-method is about 66% lower than the plate count method allowing detection of a clearly greater number of Listeria-positive samples from naturally contaminated ground meat. The MPN-method yielded more Listeria spp.-positive samples (rel. 43%) and more L. monocytogenes-positive samples (rel. 21%) versus the colony count method based on the results from the field trial using ground beef samples from retail food stores in Berlin. Nevertheless the standardized colony count method is preferred over the MPN-method for routine use because of its slightly higher productivity and much smaller variation in the results. However, the MPN-method is preferable for epidemiological studies because of the significance of the lower detection level. The random sampling evaluation of ground beef from retail stores indicated that 39% of the samples were Listeria spp.-positive and 31% were L. monocytogenes-positive when using the colony count method. A total of 56% of the meat samples were found to be Listeria spp.-positive and 38% L. monocytogenes-positive when the MPN-method was used. Population levels ranged from 10 to 580 cfu/g (Listeria spp.-positive samples) and from 10 to 270 cfu/g (L. monocytogenes-positive samples) for the colony count method. The MPN-method yielded population levels of 3.6 to 930 MPN/g for Listeria spp.-positive samples and 3.6 to 150 MPN/g for L. monocytogenes-positive samples. L. monocytogenes strains isolated using the colony count method belonged to the following serovars: 1/2a (46%), 1/2b (13%), 1/2c (33%), 3b (4%) and 4c (4%). A similar serovar isolation pattern was found for L. monocytogenes-positive MPN-tubes. The most common serotype was 1/2a (43%), followed by 1/2c (32%) and 1/2b (14%). The serotypes 3c, 4b and 4c were all isolated 4% of the time.

[Comparison of the two different PCR assays for the detection of thermotolerant Campylobacter in poultry]

In this study two PCR-assays were compared for there suitability in routine food-examination. The rapid and sensitive seminested PCR assay of Wegmueller et al. (1993) provides a useful tool for specific detection of thermotolerant Campylobacter spp. in poultry. For laboratories, which have not established hybridisation technique yet, the seminested PCR assay fulfills the necessity to verify the amplicons (Anonymous, 1998 a) and provides therefore an alternative to the published provisional method according to section 35 LMBG (Anonymous, 2000). The results clearly show that the pg50/pg3-PCR assay (Oyofo et al., 1992) isn't a useful screening method because there is a strong necessity to verify the obtained amplicons by southernblot-hybridization in order to increase sensitivity and specificity. To avoid false-negative results extern amplification controls are reliable tools. The commercially available DNA-Extraction kit used in this study facilitates rapid and effective extraction of bacterial DNA out of food matrix.

[Sampling plans in microbiological criteria for food and their "performance criteria"]

Statistically based acceptance sampling plans have been integrated into microbiological criteria for food in international trade for some time. Especially two- and three-class sampling plans for attributes are used, variables plans are applied less. A lot of examples can be found in the so-called ICMSF (International Commission on Microbiological Specifications for Foods) "sampling book" or in EU guidelines. However, quite often the required confidence and the assumptions on tolerable lot qualities on which the choice and design of sampling plans are based can't be deduced from such recommendations and prescriptions. These problems have led to critical discussion of the performance of two- and three-class sampling plans used in microbiological criteria, showing complex dependencies on microbiological limits and on the expected variability of sampling results. As a result means should be considered to use knowledge gained from process analyses in food production in the design of sampling plans. In this context the performance of acceptance sampling plans as prescribed in microbiological criteria for foods will be discussed as well as their role in recently developed food safety concepts.

[Perspectives of veterinary science--from the viewpoint of consumer health protection]

Concerning the causal chain "healthy animal--healthy food--healthy man" there's no doubt that mainly veterinarians are responsible for a safe preharvest area. In the food processing sector, of which economical importance is increasing in inverse proportion to agricultural activity of developed nations, the veterinarians must win through against many other professions. In this competition the specific veterinarian competence to prevent or to control microbiological, parasitological and some chemical hazards should be used. Therefore scientific work in veterinary public health has to concentrate on risk management. Additionally to developing methods for rapid and/or discriminative determination of causative agents the implementation of integrated quality assurance systems is needed in future according to the spirit of "intelligent" food hygiene.

[The vegetarian appeal and killing animals. An ethical challenge]

The demand for renunciation of killing animals has already been discussed by mankind since ancient times. Many arguments for and against this demand have accumulated in the meantime. The reproaches of the vegetarians repeatedly forced the ones who eat meat to justify their diet. Today most of these historical justifications however have to be rejected because of lacking plausibility. Many of the vegetarian arguments on the other hand must be rejected for similar reasons as well. Remaining as morally convincing is the demand for doing the killing absolutely painless and without frightening the animals, which was already formulated for example by Kant and Schopenhauer. Arguments which consider this way of killing as still immoral belong in a broad sense to the "anthropocentric" animal ethics. They do not belong to what is called in Germany "pathocentric" animal ethics, because an animal that is killed without being frightened or tortured, has not suffered, for it hasn't consciously realized anything like danger or harm. We do even argue that these animals are not harmed at all, because it seems senseless to talk about harm without negative conscious phenomena. To push ahead a ban on animal slaughter for moral reasons could be itself morally wrong because it would disturb indirectly many people's conscious well-being without being justified by protecting an animal's conscious well-being. It is however possible to derive from a general duty not to make animals suffer (pathocentric animal ethics) a duty to boycott food of animal origin if these animals had to suffer during their lives.

Prevalence of Salmonella in Ethiopian cattle and minced beef

To estimate the prevalence and distribution of Salmonella in the chain from cattle to the consumer, faeces, mesenteric lymphnodes and beef cuts from 235 cattle, stool samples from 300 workers of the same Addis Ababa abattoir, and 330 minced beef samples from supermarkets in Addis Ababa were analyzed. Isolated Salmonella strains were serotyped and tested for antibiotic susceptibility. Low prevalence in faeces and lymphnodes, and higher contamination rates of beef cuts (diaphragm, abdominal muscles) indicate severe cross-contamination during slaughter. Animals of poor health status were far more frequently carriers of salmonellae, which stresses the need of intensive ante-mortem inspection on slaughter animals. During transport from slaughterhouse to the supermarkets, production and selling of minced beef, the prevalence of Salmonella did not increase.