The cold atmospheric pressure plasma-generated species superoxide, singlet oxygen and atomic oxygen activate the molecular chaperone Hsp33

Cold atmospheric pressure plasmas are used for surface decontamination or disinfection, e.g. in clinical settings. Protein aggregation has been shown to significantly contribute to the antibacterial mechanisms of plasma. To investigate the potential role of the redox-activated zinc-binding chaperone Hsp33 in preventing protein aggregation and thus mediating plasma resistance, we compared the plasma sensitivity of wild-type E. coli to that of an hslO deletion mutant lacking Hsp33 as well as an over-producing strain. Over-production of Hsp33 increased plasma survival rates above wild-type levels. Hsp33 was previously shown to be activated by plasma in vitro. For the PlasmaDerm source applied in dermatology, reversible activation of Hsp33 was confirmed. Thiol oxidation and Hsp33 unfolding, both crucial for Hsp33 activation, occurred during plasma treatment. After prolonged plasma exposure, however, unspecific protein oxidation was detected, the ability of Hsp33 to bind zinc ions was decreased without direct modifications of the zinc-binding motif, and the protein was inactivated. To identify chemical species of potential relevance for plasma-induced Hsp33 activation, reactive oxygen species were tested for their ability to activate Hsp33 in vitro. Superoxide, singlet oxygen and potentially atomic oxygen activate Hsp33, while no evidence was found for activation by ozone, peroxynitrite or hydroxyl radicals.

Wissen, nicht Wahrheit

Wissen ist keine absolute Wahrheit, sondern immer sozial determiniert. Auch pädagogisches Wissen ist eine eher unübersichtliche Ansammlung von unterschiedlichen „Wahrheiten“ – sie lassen sich aber sortieren.

Characterization of an ester-based core-multishell (CMS) nanocarrier for the topical application at the oral mucosa

OBJECTIVES

Topical drug administration is commonly applied to control oral inflammation. However, it requires sufficient drug adherence and a high degree of bioavailability. Here, we tested the hypothesis whether an ester-based core-multishell (CMS) nanocarrier is a suitable nontoxic drug-delivery system that penetrates efficiently to oral mucosal tissues, and thereby, increase the bioavailability of topically applied drugs.

MATERIAL AND METHODS

To evaluate adhesion and penetration, the fluorescence-labeled CMS 10-E-15-350 nanocarrier was applied to ex vivo porcine masticatory and lining mucosa in a Franz cell diffusion assay and to an in vitro 3D model. In gingival epithelial cells, potential cytotoxicity and proliferative effects of the nanocarrier were determined by MTT and sulphorhodamine B assays, respectively. Transepithelial electrical resistance (TEER) was measured in presence and absence of CMS 10-E-15-350 using an Endohm-12 chamber and a volt-ohm-meter. Cellular nanocarrier uptake was analyzed by laser scanning microscopy. Inflammatory responses were determined by monitoring pro-inflammatory cytokines using real-time PCR and ELISA.

RESULTS

CMS nanocarrier adhered to mucosal tissues within 5 min in an in vitro model and in ex vivo porcine tissues. The CMS nanocarrier exhibited no cytotoxic effects and induced no inflammatory responses. Furthermore, the physical barrier expressed by the TEER remained unaffected by the nanocarrier.

CONCLUSIONS

CMS 10-E-15-350 adhered to the oral mucosa and adhesion increased over time which is a prerequisite for an efficient drug release. Since TEER is unaffected, CMS nanocarrier may enter the oral mucosa transcellularly.

CLINICAL RELEVANCE

Nanocarrier technology is a novel and innovative approach for efficient topical drug delivery at the oral mucosa.

Deficiency in the DNA repair protein ERCC1 triggers a link between senescence and apoptosis in human fibroblasts and mouse skin

ERCC1 (excision repair cross complementing‐group 1) is a mammalian endonuclease that incises the damaged strand of DNA during nucleotide excision repair and interstrand cross‐link repair. Ercc1^−/Δ mice, carrying one null and one hypomorphic Ercc1 allele, have been widely used to study aging due to accelerated aging phenotypes in numerous organs and their shortened lifespan. Ercc1^−/Δ mice display combined features of human progeroid and cancer‐prone syndromes. Although several studies report cellular senescence and apoptosis associated with the premature aging of Ercc1^−/Δ mice, the link between these two processes and their physiological relevance in the phenotypes of Ercc1^−/Δ mice are incompletely understood. Here, we show that ERCC1 depletion, both in cultured human fibroblasts and the skin of Ercc1^−/Δ mice, initially induces cellular senescence and, importantly, increased expression of several SASP (senescence‐associated secretory phenotype) factors. Cellular senescence induced by ERCC1 deficiency was dependent on activity of the p53 tumor‐suppressor protein. In turn, TNFα secreted by senescent cells induced apoptosis, not only in neighboring ERCC1‐deficient nonsenescent cells, but also cell autonomously in the senescent cells themselves. In addition, expression of the stem cell markers p63 and Lgr6 was significantly decreased in Ercc1^−/Δ mouse skin, where the apoptotic cells are localized, compared to age‐matched wild‐type skin, possibly due to the apoptosis of stem cells. These data suggest that ERCC1‐depleted cells become susceptible to apoptosis via TNFα secreted from neighboring senescent cells. We speculate that parts of the premature aging phenotypes and shortened health‐ or lifespan may be due to stem cell depletion through apoptosis promoted by senescent cells.

[Pedicled vascularized iliac bone graft for treatment of osteonecrosis of the femoral head]

OBJECTIVE

Illustration of a nowadays only rarely performed operative procedure for the treatment of osteonecrosis of the femoral head to prevent or at least delay advanced arthrosis and the need for a total hip replacement. The pedicled vascularized iliac bone graft is raised without the need for special microsurgical techniques and has less vascular complications often seen in free vascularized grafts.

INDICATIONS

Early stages of osteonecrosis of the femoral head stages II and III according to the Association Research Circulation Osseous (ARCO) up to the detection of fracture lines (crescent sign) but without mechanical insufficiency.

CONTRAINDICATIONS

Osteonecrosis of the femoral head with collapse of the femoral head (ARCO stage ≥IIIB) and mechanical insufficiency. Patients who are noncompliant or a not able to take the weight off the operated leg. Patients who had radiotherapy or an operation on ipsilateral inguinal lymph nodes and patients who have vascular anomalies or severe arteriosclerosis.

SURGICAL TECHNIQUE

Debridement of the femoral head osteonecrosis and implantation of a pedicled vascularized iliac bone graft.

POSTOPERATIVE MANAGEMENT

Free movement of the hip joint 4 weeks after surgery. Outward rotation of the hip joint allowed after 3 months and restriction of weight load on the operated leg for at least 3-6 months postoperatively depending on the bony consolidation.

RESULTS

Vascularized bone grafts for the treatment of femoral head necrosis show better clinical and radiological results than avascular bone grafts. Nevertheless, after 5 years follow-up approximately 25% of the operated hips formerly in stage II show further progression of radiological necrosis. In stage III all hips eventually show progress of femoral head collapse and the need of a total hip replacement. Concerning the outcome of a free vascularized bone graft (fibula flap) compared to the pedicled vascularized graft from the iliac crest for treatment, the anatomically demanding area and a higher complication rate should be considered even though the cancellous bone of the iliac crest is biologically ideal. Nowadays a free vascularized fibular graft is the most frequently used bone graft for treatment of femoral head necrosis.

Induction chemotherapy (IC) followed by radiotherapy (RT) versus cetuximab plus IC and RT in advanced laryngeal/hypopharyngeal cancer resectable only by total laryngectomy-final results of the larynx organ preservation trial DeLOS-II

Background

The German multicenter randomized phase II larynx organ preservation (LOP) trial DeLOS-II was carried out to prove the hypothesis that cetuximab (E) added to induction chemotherapy (IC) and radiotherapy improves laryngectomy-free survival (LFS; survival with preserved larynx) in locally advanced laryngeal/hypopharyngeal cancer (LHSCC).

Patients and methods

Treatment-naïve patients with stage III/IV LHSCC amenable to total laryngectomy (TL) were randomized to three cycles IC with TPF [docetaxel (T) and cisplatin (P) 75 mg/m2/day 1, 5-FU (F) 750 mg/m2/day days 1-5] followed by radiotherapy (69.6 Gy) without (A) or with (B) standard dose cetuximab for 16 weeks throughout IC and radiotherapy (TPFE). Response to first IC-cycle (IC-1) with ≥30% endoscopically estimated tumor surface shrinkage (ETSS) was used to define early responders; early salvage TL was recommended to non-responders. The primary objective was 24 months LFS above 35% in arm B.

Results

Of 180 patients randomized (July 2007 to September 2012), 173 fulfilled eligibility criteria (A/B: larynx 44/42, hypopharynx 41/46). Because of 4 therapy-related deaths among the first 64 randomized patients, 5-FU was omitted from IC in the subsequent 112 patients reducing further fatal toxicities. Thus, IC was TPF in 61 patients and TP in 112 patients, respectively. The primary objective (24 months LFS above 35%) was equally met by arms A (40/85, 47.1%) as well as B (41/88, 46.6%). One hundred and twenty-three early responders completed IC+RT; their overall response rates (TPF/TP) were 94.7%/87.2% in A versus 80%/86.0% in B. The 24 months overall survival (OS) rates were 68.2% and 69.3%.

Conclusions

Despite being accompanied by an elevated frequency in adverse events, the IC with TPF/TP plus cetuximab was feasible but showed no superiority to IC with TPF/TP regarding LFS and OS at 24 months. Both early response and 24 months LFS compare very well to previous LOP trials and recommend effective treatment selection and stratification by ETSS.

Clinical trial information

NCT00508664.

Ultrasound measurements of subcutaneous adipose tissue thickness show sexual dimorphism in children of three to five years of age

Aim

A standard approach to measure subcutaneous adipose tissue (SAT) using ultrasound has proved successful in adults, but has not been studied in children. This study addressed that gap in children aged three to five years.

Methods

In autumn 2016, 24 preschools in Southwest Germany, recruited via mail, agreed to take part in this study and 274 children (51.4% boys) with a mean age of 4.6 ± 0.7 years participated in measurements of SAT and anthropometry. Differences in measurements were explored between the sexes and anthropometric predictors of mean SAT thickness were identified. Intra‐observer reliability for ultrasound measurements of SAT was also assessed.

Results

The mean SAT thickness showed significant differences between the boys and girls (5.3 ± 2.0 and 6.3 ± 2.0 mm, respectively, p < 0.01). The children's body mass, height and sex explained 66% of the variance in the mean SAT thickness, as SAT was larger with a higher body mass, a smaller stature and in girls. Intra‐observer reliability resulted in an intra‐class correlation coefficient of 0.994 (p < 0.01) with a 95% confidence interval of 0.983–0.998.

Conclusion

Subcutaneous adipose tissue thickness differed between boys and girls with a mean age of 4.6 years. Intra‐observer reliability was excellent. This standardised approach enabled high‐precision measurements of SAT in a paediatric population.

Abstract 4697: Intratumoral immunotherapy with TLR7/8 agonist MEDI9197 modulates the tumor microenvironment and holds potential for combination with immune checkpoint inhibitors

Recent successes in immuno-oncology have focussed primarily on the T-cell synapse, targeting co-activatory /inhibitory pathways to modulate T cell function. However, strategies that target tumor-resident myeloid cells may be required to fully exploit the therapeutic potential of the anti-cancer immune response. TOLL-like receptors (TLRs) are expressed on a broad range of myeloid cells and function to recognise highly evolutionarily conserved pathogen-associated molecular patterns. Signalling through TLRs leads to the activation of antigen-presenting cells (APCs) and to expression of inflammatory cytokines. However, whilst topical application of TLR agonists have proved successful in the treatment of dermatological tumors, systemic administration have proved to be poorly tolerated. MEDI9197 (formerly 3M-052), is a novel lipophilic TLR7/8 agonist designed with a lipid tail to facilitate retention at the site of injection, limiting systemic exposure. These properties make MEDI9197 ideal for intratumoral (IT) administration. We have demonstrated that MEDI9197 is a potent TLR7 and TLR8 agonist and induces pro-inflammatory cytokines through activation of a diverse range of myeloid and lymphoid cells. In mice bearing established tumors, IT injection of MEDI9197 induces a local inflammatory response, characterized by upregulation of genes associated with the activation of innate and adaptive immunity in the injected tumor and tumor draining lymph nodes. Moreover, treatment leads to an increase in the frequency of tumor infiltrating lymphocytes (TILs), such as CD8+ cytotoxic T cells and increased expression of activation markers, such as CD69. Cellular depletion studies reveal that CD8+ T cells are required for therapeutic activity. Furthermore, using in vitro co-cultures we demonstrate that MEDI9197 is able to enhance cytotoxic activity of NK cell and T cells. Importantly, in models that respond poorly to mAbs targeting either PD-L1 or CTLA-4, combination with MEDI9197 significantly improved anti-tumor activity when compared to either monotherapy alone. These preclinical data demonstrate that MEDI9197 can modulate both the myeloid and lymphoid immune compartments to mediate anti-tumor activity and combines productively with immune checkpoint blockade. MEDI9197 is currently being evaluated as a monotherapy for safety and efficacy in human clinical trials (NCT02556463).

Citation Format: Stefanie R. Mullins, Katharina Vogel, John Vasilakos, Iwen Grigsby, Simon Dovedi, Ryan Patricia, Zachary Cooper, Ronald Herbst, Rakesh Kumar, Mark Tomai, Robert W. Wilkinson. Intratumoral immunotherapy with TLR7/8 agonist MEDI9197 modulates the tumor microenvironment and holds potential for combination with immune checkpoint inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4697. doi:10.1158/1538-7445.AM2017-4697

Maintaining knife sharpness in industrial meat cutting: A matter of knife or meat cutter ability

Knife sharpness is imperative in meat cutting. The aim of this study was to compare the impact of knife blade steel quality with meat cutters' individual ability to maintain the cutting edge sharp in an industrial production setting. Twelve meat cutters in two different companies using three different knives during normal production were studied in this quasi-experimental study. Methods included were measuring knife cutting force before and after knife use, time knives were used, ratings of sharpness and discomfort and interviews. Results showed that the meat cutters' skill of maintaining sharpness during work had a much larger effect on knife sharpness during work than the knife steel differences. The ability was also related to feelings of discomfort and to physical exertion. It was found that meat cutters using more knives were more likely to suffer from discomfort in the upper limbs, which is a risk for developing MSD.

Increased work pace is unprofitable: a beef-cutting case study

The beef industry worldwide is showing a trend towards increased cutting pace aimed at higher profits. However, prior research in the duck meat industry suggested that a higher cutting pace reduced quality and yield, leading to losses. This study aimed to test this hypothesis by investigating the effects of varying beef-cutting paces on yield, quality and economy. A field experiment was conducted on six workers cutting beef fillet, sirloin and entrecôte. Three types of paces were sequentially tested: Baseline (i.e., status quo), 'Quantity focus' (i.e., pace required to maximise quantity) and 'Quality focus' (i.e., pace required to minimise errors). The results showed a significant drop in yield, increased rate of quality deficiency and economic losses with the change to 'Quantity focus' (from Baseline and 'Quality focus') for all meat types. Workers supported these results and also added health problems to the list. The results confirmed that an increased cutting pace is unprofitable.

Chromatographische Fraktionierung und Trennung von Polystyrolen an Silicagel

Silica gel as a filler of separation columns fractionates and separates dissolved polystyrenes. Fractionation means: Continuous distribution of the polymeric homologues among the successive fractions of the eluate. Separation means: Discontinuous distribution. In both cases the polymeric homologues with higher molecular weights are transported more rapidly through the columns than the polymeric homologues with lower molecular weigths. Fractionation and separation of polystyrenes are based on characteristics of the space system within the silica gel particles. With equal dimensions of the columns fractionation and separation grow with the pore size of the silica gel particles.

Improving meat cutters' work: changes and effects following an intervention

Meat cutters face higher risks of injury and musculoskeletal problems than most other occupational groups. The aims of this paper were to describe ergonomics changes implemented in three meat cutting plants and to evaluate effects related to ergonomics on the individual meat cutters and their work. Data was collected by interviews, observations, document studies and a questionnaire (n = 247), as a post intervention study. The changes implemented consisted of reducing knife work to a maximum of 6 h per day and introducing a job rotation scheme with work periods of equal length. Tasks other than traditional meat cutting were added. A competence development plan for each meat cutter and easy adjustment of workplace height were introduced. The questionnaire showed a reduction in perceived physical work load. In general, the changes were perceived positively. Figures from the company showed a positive trend for injuries and sick leave.

Relationship between estimated glomerular filtration rate and biological half-life of 131I. Retrospective analysis in patients with differentiated thyroid carcinoma

AIM

This retrospective study sought to investigate the relationship between biological half-life (t1/2 biol) of 131I and estimated glomerular filtration rate (eGFR) in patients with thyroid carcinoma.

PATIENTS, METHODS

96 patients with differentiated thyroid carcinoma (69 women, 27 men, mean age 64.0 ± 13.6 years) and diagnostic and therapeutic administration of 131I were considered. Patients with pronounced specific iodine storage were not included in the study. The eGFR was estimated according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula, the t1/2 biol via dosimetry. Patients were subdivided in groups with normal clearance (NC) (n = 37, 38.5%), medium clearance (MC) (n = 48, 50.0%), and low clearance (LC) (n = 11, 11.5%) (eGFR ≥ 90; 60-89; 15-59 ml/min per 1.73 m2, respectively). The relationship between eGFR and t1/2 biol of 131I was modeled using a power function.

RESULTS

The groups significantly differed in terms of age (NC 53.8, MC 68.6, and 78.0 years, respectively), serum creatinine levels (NC: 0.71; MC: 0.85; LC: 1.18 mg/dl), and t1/2 biol (NC: 0.53; MC: 0.71; LC: 1.01 days). The t1/2 biol was significantly influenced only by eGFR, and not by age, gender, or body weight. The relationship between t1/2 biol of 131I and eGFR was described by the formula t1/2 biol = 20.3 · eGFR-0.782.

CONCLUSIONS

The calculated relationship between renal function and t1/2 biol of 131I can be used in principle to estimate a dose reduction for patients with renal insufficiency. The model, however, gives erroneous results in individual cases and therefore a routine utilization cannot be recommended. Prospective studies are necessary, based on larger patient numbers and more accurate methods for dose rate measurement and GFR.

Relationship between estimated glomerular filtration rate and biological half-life of 131I

Aim: This retrospective study sought to investigate the relationship between biological half-life (t 1/2 biol ) of 131I and estimated glomerular filtration rate (eGFR) in patients with thyroid carcinoma. Patients, methods: 96 patients with differentiated thyroid carcinoma (69 women, 27 men, mean age 64.0 ± 13.6 years) and diagnostic and therapeutic administration of 131I were considered. Patients with pronounced specific iodine storage were not included in the study. The eGFR was estimated according to the Chronic Kidney Disease Epidemiology Collaboration (CKDEPI) formula, the t 1/2 biol via dosimetry. Patients were subdivided in groups with normal clearance (NC) (n = 37, 38.5%), medium clearance (MC) (n = 48, 50.0%), and low clearance (LC) (n = 11, 11.5%) (eGFR _ 90; 60-89; 15-59 ml/min per 1.73 m2, respectively). The relationship between eGFR and t 1/2 biol of 131I was modeled using a power function. Results: The groups significantly differed in terms of age (NC 53.8, MC 68.6, and 78.0 years, respectively), serum creatinine levels (NC: 0.71; MC: 0.85; LC: 1.18 mg/dl), and t 1/2 biol (NC: 0.53; MC: 0.71; LC: 1.01 days). The t 1/2 biol was significantly influenced only by eGFR, and not by age, gender, or body weight. The relationship between t 1/2 biol of 131I and eGFR was described by the formula t 1/2 biol = 20.3 · eGFR−0.782. Conclusions: The calculated relationship between renal function and t 1/2 biol of 131I can be used in principle to estimate a dose reduction for patients with renal insufficiency. The model, however, gives erroneous results in individual cases and therefore a routine utilization cannot be recommended. Prospective studies are necessary, based on larger patient numbers and more accurate methods for dose rate measurement and GFR.

Supervisors in ergonomic change of meat cutting work

Being a supervisor is an important and lonely occupation. The aim of this study was to identify barriers and opportunities in working conditions for supervisors, being facilitators and implementers of change for meat cutters. Nine supervisors of meat cutters in one large company were interviewed. The semi-structured interviews covered their roles as supervisors, performance of the change process and their own working conditions. Notes were taken and structured in themes. Similarities, differences, plus and minus were identified. There was a nuanced view on the change processes and their effects. The change processes and the decisions were anchored in a democratic process with groups of employees and the union. All were clear on what demands the company had on them. They were secure in a functioning network of peers and their immediate superior. On their own education, most were as a whole satisfied, but in need of more training and talked of lifelong learning. They considered their work demanding and lonely, with a need both to be manager and leader. A shared leadership could mean doing a better job. There is a need for education and training as a manager and leader as well as the opportunity to discuss with peers.

Distinct adrenergic system changes and neuroinflammation in response to induced locus ceruleus degeneration in APP/PS1 transgenic mice

Degeneration of locus ceruleus (LC) neurons and subsequent reduction of norepinephrine (NE) in LC projection areas represent an early pathological indicator of Alzheimer's disease (AD). In order to study the effects of NE depletion on cortical and hippocampal adrenergic system changes, LC degeneration was induced in 3-month-old APP/PS1 mice by the neurotoxin N-(2-chloroethyl)-N-ethyl-bromo-benzylamine (dsp4). Dsp4 induced a widespread loss of norepinephrine transporter binding in multiple brain structures already at 4.5 months. This was accompanied by changes of α-1-, α-2-, and β-1-adreneroceptor binding sites as well as altered adrenoceptor mRNA expression. In parallel, we observed increased micro- and astrogliosis in cortical and hippocampal structures in dsp4-treated groups. In addition, the expression of the pro-inflammatory cytokines CCL2 and IL-1β were induced in both, dsp4-treated and APP/PS1-transgenic mice, whereas IL-1α was only up-regulated in dsp4-treated APP/PS1 mice. Concerning amyloid β (Aβ) deposition, we observed an elevation of Aβ1-42 levels in aged dsp4-treated APP/PS1 mice. These data support the hypothesis that LC degeneration leads to dysregulation of adrenergic receptors and exacerbation of Aβ-induced neuroinflammation, both of which are exploitable for early disease marker development.

Myelodysplasia in 2 pig-tailed macaques (Macaca nemestrina) associated with retroviral vector-mediated insertional mutagenesis and overexpression of HOXB4

Gammaretroviral vectors are an efficient means to effect gene therapy. However, genotoxicity from insertion at nonrandom sites can confer a competitive advantage to transduced cells, resulting in clonal proliferation or neoplasia. Six pig-tailed macaques (Macaca nemestrina) underwent total body irradiation and reconstitution with autologous stem cells genetically modified by a gammaretroviral vector overexpressing HOXB4. Two animals were euthanized owing to irradiation- or transplantation-associated toxicity, whereas the other 4 had successful reconstitution. Of the 4 macaques with successful reconstitution, 1 has no long-term follow-up information; 1 was euthanized owing to infection with simian varicella virus infection 18 months post-total body irradiation; and the 2 others are described herein as case Nos. 1 and 2. After being stable for 3 years, case No. 1 developed pancytopenia and petechiation, and after 2 years of stability case No. 2 developed anemia and thrombocytopenia. Despite therapy, the animals deteriorated and were euthanized. Gross findings included emaciation; case No. 1 also had hemorrhage, peritonitis, and cholecystitis. Histologically, bone marrow was hypercellular with predominately blast cells of all hematopoietic lineages, though with myeloid predominance, and with maturation arrest and blast cell dysplasia (myelodysplasia). Myelodysplasia was likely from a combination of insertional mutagenesis by the retroviral vector and overexpression of HOXB4. Consequences of myelodysplasia included the blood dyscrasias and, in case No. 1, hemorrhage, bacterial cholecystitis, hepatitis, and peritonitis.

Filler features and their effects on wear and degree of conversion of particulate dental resin composites

Based on the incomplete understanding on how filler features influence the wear resistance and monomer conversion of resin composites, this study sought to evaluate whether materials containing different shapes and combinations of size of filler particles would perform similarly in terms of three-body abrasion and degree of conversion. Twelve experimental monomodal, bimodal or trimodal composites containing either spherical or irregular shaped fillers ranging from 100 to 1500 nm were examined. Wear testings were conducted in the OHSU wear machine (n = 6) and quantified after 10(5) cycles using a profilometer. Degree of conversion (DC) was measured by FTIR spectrometry at the surface of the composites (n = 6). Data sets were analyzed using one-way Anova and Tukey's test at a significance level of 0.05. Filler size and geometry was found to have a significant effect on wear resistance and DC of composites. At specific sizes and combinations, the presence of small filler particles, either spherical or irregular, may aid in enhancing the wear resistance of composites, without compromising the percentage of reacted carbon double bonds.

Characteristics of fungal phytases from Aspergillus fumigatus and Sartorya fumigata

Aspergillus fumigatus phytase has previously been identified as a phytase with a series of favourable properties that may be relevant in animal and human nutrition, both for maximising phytic acid degradation and for increasing mineral and amino acid availability. To study the natural variability in amino acid sequence and its impact on the catalytic properties of the enzyme, we cloned and overexpressed the phytase genes and proteins from six new purported A. fumigatus isolates. Five of these phytases displayed < or= 2 amino acid substitutions and had virtually identical stability and catalytic properties when compared with the previously described A. fumigatus ATCC 13073 phytase. In contrast, the phytase from isolate ATCC 32239 ( Sartorya fumigata, the anamorph of which was identified as A. fumigatus) was more divergent (only 86% amino acid sequence identity), had a higher specific activity with phytic acid, and displayed distinct differences in substrate specificity and pH-activity profile. Finally, comparative experiments confirmed the favourable stability and catalytic properties of A. fumigatus phytase.

Tumor vascularization in experimental melanomas: correlation between unenhanced and contrast enhanced power Doppler imaging and histological grading

The purpose of this study was to evaluate the reliability of unenhanced and enhanced power Doppler sonography in visualization of intratumoral angioneogenesis. Thirty-seven malignant melanomas, which had been implanted intra- or subcutaneously in 22 mice, were examined. Various B-mode criteria, power Doppler criteria and spectral Doppler parameters were evaluated before and after IV-application of the d-galactose-based contrast agent Levovist. After sonographic examination, all tumors were analyzed histologically with semiquantitative grading of tumoral vascularization. Unenhanced, in 70% of the tumors, no intratumoral vessels were visible using power Doppler, but only in 11% of the intracutaneous and in 0% of the subcutaneous after injection of the contrast agent. The enhanced mode was definitely superior to unenhanced Doppler in showing the intratumoral vascularity. The intratumoral vascular structure could be sufficiently analyzed in 30% of all tumors by unenhanced Doppler, but in 92% enhanced. The mean percentage vessel area increased about 433% after application of Levovist (intracutaneous: 485%, subcutaneous: 280%). Despite the missing direct correlation between the sonographically and histologically determined grade of tumor vascularization (Pearson's correlation unenhanced 0,356, p <.05/enhanced 0.395, p <.05), the correlation between the percentage vessel area and the histologic grade of vascularization was improved after application of the contrast agent (Pearson's correlation unenhanced 0.347, p <.05/enhanced 0.686, p <.01). We did not find a significant direct correlation between histologically and sonographically determined degree of vascularization. However, the correlation was improved using a d-galactose-based signal-enhancing agent in power Doppler sonography.

Carbon monoxide binding by de novo heme proteins derived from designed combinatorial libraries

Carbon monoxide binding was studied in a collection of de novo heme proteins derived from combinatorial libraries of sequences designed to fold into 4-helix bundles. The design of the de novo sequences was based on the previously reported "binary code" strategy, in which the patterning of polar and nonpolar amino acids is specified explicitly, but the exact identities of the side chains are varied extensively.(1) The combinatorial mixture of amino acids included histidine and methionine, which ligate heme iron in natural proteins. However, no attempt was made to explicitly design a heme binding site. Nonetheless, as reported previously, approximately half of the binary code proteins bind heme.(2) This collection of novel heme proteins provides a unique opportunity for an unbiased assessment of the functional potentialities of heme proteins that have not been prejudiced either by explicit design or by evolutionary selection. To assess the capabilities of the de novo heme proteins to bind diatomic ligands, we measured the affinity for CO, the kinetics of CO binding and release, and the resonance Raman spectra of the CO complexes for eight de novo heme proteins from two combinatorial libraries. The CO binding affinities for all eight proteins were similar to that of myoglobin, with dissociation constants (K(d)) in the low nanomolar range. The CO association kinetics (k(on)) revealed that the heme environment in all eight of the de novo proteins is partially buried, and the resonance Raman studies indicated that the local environment around the bound CO is devoid of hydrogen-bonding groups. Overall, the CO binding properties of the de novo heme proteins span a narrow range of values near the center of the range observed for diverse families of natural heme proteins. The measured properties of the de novo heme proteins can be considered as a "default" range for CO binding in alpha-helical proteins that have neither been designed to bind heme or CO, nor subjected to genetic selections for heme or CO binding.

Active site residue 297 of Aspergillus niger phytase critically affects the catalytic properties

The wild-type phytases from the Aspergillus niger strains NRRL 3135 and T213 display a three-fold difference in specific activity (103 versus 32 U/mg protein), despite only 12 amino acid differences that are distributed all over the sequence of the protein. Of the 12 divergent positions, three are located in or close to the substrate binding site. Site-directed mutagenesis of these residues in A. niger T213 phytase showed that the R297Q mutation (R in T213, Q in NRRL 3135) fully accounts for the differences in catalytic properties observed. Molecular modelling revealed that R297 may directly interact with a phosphate group of phytic acid. The fact that this presumed ionic interaction - causing stronger binding of substrates and products - correlates with a lower specific activity indicates that product (myo-inositol pentakisphosphate) release is the rate-limiting step of the reaction.

Targeting of SNAP-25 to membranes is mediated by its association with the target SNARE syntaxin

The docking and fusion of synaptic vesicles with the presynaptic plasma membrane require the interaction of the vesicle-associated membrane protein VAMP with the plasma membrane proteins syntaxin and SNAP-25. Both of these proteins behave as integral membrane proteins, although they are unusual in that they insert into membranes post-translationally. Whereas VAMP and syntaxin possess hydrophobic transmembrane domains, SNAP-25 does not, and it is widely believed that SNAP-25 traffics to and inserts into membranes by post-translational palmitoylation. In pulse-chase biosynthesis studies, we now show that SNAP-25 and syntaxin rapidly bind to each other while still in the cytosol of neuroendocrine and transfected heterologous cells. Cell fractionation studies revealed that cytosolic SNAP-25.syntaxin complexes then traffic to and insert into membranes. Furthermore, the association of SNAP-25 with membranes is dramatically enhanced by syntaxin, and the transmembrane domain of syntaxin is essential for this effect. Surprisingly, despite the importance of the SNAP-25 palmitoylation domain for membrane anchoring at steady state, removal of this domain did not inhibit the initial association of newly synthesized SNAP-25 with membranes in the presence of syntaxin. These data demonstrate that the initial attachment of newly synthesized SNAP-25 to membranes is a consequence of its association with syntaxin and that it is only after syntaxin-mediated membrane tethering that SNAP-25 is palmitoylated.

SPIO-MR imaging versus double-phase spiral CT in detecting malignant lesions of the liver

PURPOSE

To assess the diagnostic performance of superparamagnetic iron oxide MR (SPIO-MR) imaging compared with double-phase spiral CT in detecting liver metastases and hepatocellular carcinoma.

MATERIAL AND METHODS

Thirty-eight patients with a total of 144 malignant lesions of the liver were examined by CT and SPIO-MR. After definition of a gold standard by a panel of experts, the patient images were randomized and presented to a blinded jury of 5 independent observers whose task was to identify as many lesions as possible. The results were tested for statistical significance using multifactorial analysis of variance (alpha=5%).

RESULTS

SPIO-MR produced the highest detection rate and was significantly superior (p<0.05) to unenhanced MR imaging and double spiral-phase contrast-enhanced CT (DPS-CECT). Maximum performance in DPS-CECT was obtained during the portal venous contrast phase but was significantly inferior to SPIO-MR imaging. The scores for unenhanced CT and unenhanced MR were significantly lower than for the corresponding enhanced procedures. SPIO-MR imaging produced a higher incidence of false-positive findings (n=39).

CONCLUSION

SPIO-MR produced a significantly better detection rate for malignant focal liver lesions compared with double-phase spiral DPS-CECT but was associated with a higher rate of false-positive findings.

SNAP-23 and SNAP-25 are palmitoylated in vivo

The neuronal presynaptic membrane t-SNARE complex consists of the transmembrane protein syntaxin with the palmitoylated protein SNAP-25. In non-neuronal tissues, SNAP-23 replaces SNAP-25 in the t-SNARE complex, although the mechanism of membrane anchoring of SNAP-23 has not been determined. We now report that like SNAP-25, SNAP-23 is palmitoylated in vivo on one or more cysteine residues present in a central "palmitoylation domain." Interestingly, SNAP-23 is palmitoylated less well than SNAP-25, and in vivo binding studies indicate a correlation between the extent of palmitoylation and the ability of SNAP-23 or SNAP-25 to bind to syntaxin in vivo.