Cytotoxic and allergenic potential of bioactive proteins and peptides

This review article deals with the assessment of cytotoxic and allergenic potential of bioactive proteins and peptides. It is evident that 'novel' foods or nutraceuticals containing bioactive proteins and peptides must fulfill their proposed "health claim". Furthermore, there is a need to assess their potential to exert adverse effects before they can be made widely available to consumers. A brief overview of compounds (i.e. proteins and peptides of animal and plant origin) and mechanisms involved in cytotoxic and allergenic (adverse) reactions is given along with some recent results obtained from ongoing studies. There are numerous proteins and peptides of plant and animal origin that are known to exhibit cytotoxic effects. There is evidence that many cytotoxic compounds described in the literature exclusively affect malignant cells leading to the assumption that a cancer protective effect could exist for such bioactive proteins and peptides. All the constituents that are responsible for the allergenicity of foods (as well as of pollens) are proteinaceous in nature. Some protein breakdown products, i.e. peptide fragments, may conserve part of the allergenicity of the native protein and thus can also be considered as allergens. The molecular basis of IgE recognition underlying cow's milk protein allergy is described. Some results from studies on volunteers fed caseinophosphopeptides or potentially hypotensive milk protein hydrolysates illustrate the major difference between allergenicity and immunogenicity. The data presented on the relationship between the structure of food proteins and peptides and their allergenicity shows the difficulty in trying to assess the "non-allergenicity" of products derived from an allergenic source, even if the process used involved extensive hydrolysis of the native protein(s). A 'weight of evidence approach' for assessing the potential allergenicity of a novel protein with no history of prior allergenicity is also presented with regard to the current EU Regulations.     

Pharmacological modulation of subliminal learning in Parkinson's and Tourette's syndromes

Theories of instrumental learning aim to elucidate the mechanisms that integrate success and failure to improve future decisions. One computational solution consists of updating the value of choices in proportion to reward prediction errors, which are potentially encoded in dopamine signals. Accordingly, drugs that modulate dopamine transmission were shown to impact instrumental learning performance. However, whether these drugs act on conscious or subconscious learning processes remains unclear. To address this issue, we examined the effects of dopamine-related medications in a subliminal instrumental learning paradigm. To assess generality of dopamine implication, we tested both dopamine enhancers in Parkinson''s disease (PD) and dopamine blockers in Tourette''s syndrome (TS). During the task, patients had to learn from monetary outcomes the expected value of a risky choice. The different outcomes (rewards and punishments) were announced by visual cues, which were masked such that patients could not consciously perceive them. Boosting dopamine transmission in PD patients improved reward learning but worsened punishment avoidance. Conversely, blocking dopamine transmission in TS patients favored punishment avoidance but impaired reward seeking. These results thus extend previous findings in PD to subliminal situations and to another pathological condition, TS. More generally, they suggest that pharmacological manipulation of dopamine transmission can subconsciously drive us to either get more rewards or avoid more punishments.     

A coiled-coil motif that sequesters ions to the hydrophobic core

Most core residues of coiled coils are hydrophobic. Occasional polar residues are thought to lower stability, but impart structural specificity. The coiled coils of trimeric autotransporter adhesins (TAAs) are conspicuous for their large number of polar residues in position d of the core, which often leads to their prediction as natively unstructured regions. The most frequent residue, asparagine (N@d), can occur in runs of up to 19 consecutive heptads, frequently in the motif [I/V]xxNTxx. In the Salmonella TAA, SadA, the core asparagines form rings of interacting residues with the following threonines, grouped around a central anion. This conformation is observed generally in N@d layers from trimeric coiled coils of known structure. Attempts to impose a different register on the motif show that the asparagines orient themselves specifically into the core, even against conflicting information from flanking domains. When engineered into the GCN4 leucine zipper, N@d layers progressively destabilized the structure, but zippers with 3 N@d layers still folded at high concentration. We propose that N@d layers maintain the coiled coils of TAAs in a soluble, export-competent state during autotransport through the outer membrane. More generally, we think that polar motifs that are both periodic and conserved may often reflect special folding requirements, rather than an unstructured state of the mature proteins.     

Stellenwert des kontrastverst?rkten Ultraschalls bei der Beurteilung des Morbus Crohn

Ohne Zusammenfassung

---

Four consecutive multicenter phase II trials of adjuvant chemoradiation in patients with completely resected high-risk gastric cancer: the experience of the German AIO/ARO/CAO group

Purpose

Feasibility and efficacy of four different adjuvant radiochemotherapy regimens in patients with completely resected gastric cancer were evaluated in consecutive cooperative phase II trials using different 5-fluorouracil (5-FU)-based combination chemotherapies (CTX) and 5-FU-enhanced radiotherapy.

Methods

Between 2000 and 2005, 157 patients with completely resected gastric adenocarcinoma were included. The study design was based on two cycles of CTX and irradiation with 45 Gy plus concomitant 5-FU 225 mg/m² per 24 h between these two cycles. CTX cycles consisted of 5-FU, folinic acid (FA), cisplatin plus paclitaxel (FLPP); 5-FU, FA and cisplatin (FLP); 5-FU, FA and irinotecan (FLI); or 5-FU, cisplatin plus docetaxel (FPD).

Results

Median follow-up for all four trials was 18 months (range, 1–64) without significant difference between the four regimens: FLPP 30 months (2–46+), FLP 18 months (1–64+), FLI 15 months (1–26), FPD 10 months (5–19+). Treatment associated toxicity was tolerable and did not differ significantly between the four CTX regimens. Across all patients grade ¾, toxicities during the first cycle/chemoradiation/second cycle consisted of leukocytopenia 4%/2%/30%, anorexia 5%/10%/6%, diarrhea 6%/1%/3%, nausea 2%/7%/2%. Early death occurred in one patient due to Pneumocystis carinii pneumonia. Median progression free survival was 23 months for FLPP, 18 months for FLP, 14 months for FLI, 9 months for FPD (not significant). One-year-overall survival rates were 95% for FLPP, 82% for FLP, 94% for FLI, 86% for FPD.

Conclusion

Adjuvant radiochemotherapy in patients with gastric cancer can be safely given continuous infusion of 5-FU at 225 mg/m² per day. In addition, a variety of 5-FU-based multiagent chemotherapy regimen with defined activity in gastric cancer appears both safe and effective when given prior and after radiochemotherapy in this setting.

     

Development of a biological screening system for the evaluation of highly active and selective 17beta-HSD1-inhibitors as potential therapeutic agents

17beta-Hydroxysteroid dehydrogenase type 1 (17beta-HSD1) catalyses the intracellular conversion of oestrone (E1) to oestradiol (E2). E2 is known to be involved in the development and progression of breast cancer and endometriosis. Since 17beta-HSD1 is overexpressed in these oestrogen-dependent diseases, inhibition of this enzyme may be a more target-directed therapeutical approach compared to established medical treatments. For the identification of highly active and selective 17beta-HSD1-inhibitors that are suitable for application as potential therapeutics, there is a need for an appropriate, efficient and reliable screening system. Here, we report the development and application of our screening system using our in house library of potential 17beta-HSD1-inhibitors. Four potent and selective compounds with a good first pharmacokinetic profile were identified.     

Hand augmentation with stabilized hyaluronic acid (Macrolane™ VRF20 and Restylane® Vital,Restylane® Vital Light)

Volume augmentation of the back of the hand is a new technique which is not yet often employed. We describe the treatment of two patients who received hyaluronic acid products produced by Q‐Med (Macrolane? VRF20, Restylane^® Vital and Vital Light). The injections of Macrolane? VRF 20 were done by feathering technique using a long and blunt 18 gauge canula while Restylane^® was injected by tunneling or tenting technique with a 30 gauge needle. Significant adverse events did not occur. After injection of the hyaluronic acid fillers, the appearance of the back of the hands was improved. Both patients were very satisfied with the result.