Multifaceted Activities of Seven Nanobodies against Complement C4b

Cleavage of the mammalian plasma protein C4 into C4b initiates opsonization, lysis, and clearance of microbes and damaged host cells by the classical and lectin pathways of the complement system. Dysregulated activation of C4 and other initial components of the classical pathway may cause or aggravate pathologies, such as systemic lupus erythematosus, Alzheimer disease, and schizophrenia. Modulating the activity of C4b by small-molecule or protein-based inhibitors may represent a promising therapeutic approach for preventing excessive inflammation and damage to host cells and tissue. Here, we present seven nanobodies, derived from llama (Lama glama) immunization, that bind to human C4b (Homo sapiens) with high affinities ranging from 3.2 nM to 14 pM. The activity of the nanobodies varies from no to complete inhibition of the classical pathway. The inhibiting nanobodies affect different steps in complement activation, in line with blocking sites for proconvertase formation, C3 substrate binding to the convertase, and regulator-mediated inactivation of C4b. For four nanobodies, we determined single-particle cryo-electron microscopy structures in complex with C4b at 3.4–4 Å resolution. The structures rationalize the observed functional effects of the nanobodies and define their mode of action during complement activation. Thus, we characterized seven anti-C4b nanobodies with diverse effects on the classical pathway of complement activation that may be explored for imaging, diagnostic, or therapeutic applications.

Diverse binding properties are revealed for seven nanobodies against C4b.

Cryo-electron microscopy structures of C4b–nanobody complexes indicate nanobodies’ modes of action.

Nanobodies have therapeutic potential and are useful for labeling studies.

Stochastic palmitoylation of accessible cysteines in membrane proteins revealed by native mass spectrometry

Palmitoylation affects membrane partitioning, trafficking and activities of membrane proteins. However, how specificity of palmitoylation and multiple palmitoylations in membrane proteins are determined is not well understood. Here, we profile palmitoylation states of three human claudins, human CD20 and cysteine-engineered prokaryotic KcsA and bacteriorhodopsin by native mass spectrometry. Cysteine scanning of claudin-3, KcsA, and bacteriorhodopsin shows that palmitoylation is independent of a sequence motif. Palmitoylations are observed for cysteines exposed on the protein surface and situated up to 8 Å into the inner leaflet of the membrane. Palmitoylation on multiple sites in claudin-3 and CD20 occurs stochastically, giving rise to a distribution of palmitoylated membrane-protein isoforms. Non-native sites in claudin-3 indicate that membrane-protein function imposed evolutionary restraints on native palmitoylation sites. These results suggest a generic, stochastic membrane-protein palmitoylation process that is determined by the accessibility of palmitoyl-acyl transferases to cysteines on membrane-embedded proteins, and not by a preferred substrate-sequence motif.

Computer-based estimation of the hip joint reaction force and hip flexion angle in three different sitting configurations

Sitting is part of our daily work and leisure activities and can be performed in different configurations. To date, the impact of different sitting configurations on hip joint loading has not been studied. We therefore evaluated the hip joint reaction force (HJRF) and hip flexion angle in a virtual representative male Caucasian population by means of musculoskeletal modelling of three distinct sitting configurations: a simple chair, a car seat and a kneeling chair configuration. The observed median HJRF in relation to body weight and hip flexion angle, respectively, was 22.3% body weight (%BW) and 63° for the simple chair, 22.5%BW and 79° for the car seat and 8.7%BW and 50° for the kneeling chair. Even though the absolute values of HJRF are low compared to the forces generated during dynamic activities, a relative reduction of over 50% in HJRF was observed in the kneeling chair configuration. Second, the hip flexion angles were both in the kneeling chair (-29°) and simple chair configuration (-16°) lower compared to the car seat and, as such, did not reach the threshold value for femoroacetabular conflict. In conclusion, the kneeling chair appears to hold the greatest potential as an ergonomic sitting configuration for the hip joint.

Formation and structure of a NAIP5-NLRC4 inflammasome induced by direct interactions with conserved N- and C-terminal regions of flagellin

The NOD-like receptors NAIP5 and NLRC4 play an essential role in the innate immune response to the bacterial tail protein flagellin. Upon flagellin detection, NAIP5 and NLRC4 form a hetero-oligomeric inflammasome that induces caspase-1-dependent cell death. So far, both the mechanism of formation of the NAIP5-NLRC4 inflammasome and its structure are poorly understood. In this study we combine inflammasome reconstitution in HEK293 cells, purification of inflammasome components, and negative stain electron microscopy to address these issues. We find that a Salmonella typhimurium flagellin fragment comprising the D0 domain and the neighboring spoke region is able to co-precipitate NAIP5 and induce formation of the NAIP5-NLRC4 inflammasome. Comparison with smaller fragments indicates that flagellin recognition is mediated by its C-terminal residues as well as the spoke region. We reconstitute the inflammasome from purified flagellin, NAIP5, and NLRC4, thus proving that no other cellular components are required for its formation. Electron micrographs of the purified inflammasome provide unprecedented insight into its architecture, revealing disk-like complexes consisting of 11 or 12 protomers in which NAIP5 and NLRC4 appear to occupy equivalent positions. On the basis of our data, we propose a model for inflammasome formation wherein direct interaction of flagellin with a single NAIP5 induces the recruitment and progressive incorporation of NLRC4, resulting in the formation of a hetero-oligomeric inflammasome.

Systemically induced resistance and microbial competitive exclusion: implications on biological control

The root-knot nematode, Meloidogyne incognita, is among the most damaging agricultural pests, particularly to tomato. The mutualistic endophytes Fusarium oxysporum strain Fo162 (Fo162) and Rhizobium etli strain G12 (G12) have been shown to systemically induce resistance toward M. incognita. By using triple-split-root tomato plants, spatially separated but simultaneous inoculation of both endophytes did not lead to additive reductions in M. incognita infection. More importantly, spatially separated inoculation of Fo162 and G12 led to a reduction in Fo162 root colonization of 35 and 39% when G12 was inoculated on a separate root section of the same plant in two independent experiments. In an additional split-root experiment, spatial separation of Fo162 and G12 resulted in a reduction of Fo162 root colonization of approximately 50% over the water controls in two independent experiments. The results suggested that the suppressive activity of G12 on Fo162 and M. incognita is possibly related to the induction of specific plant defense mechanisms. Thus, although Fo162 and G12 have the ability to systemically repress M. incognita infection in tomato, they can be considered incompatible biocontrol agents when both organisms are present simultaneously on the same root system.

L-Alanine methyl ester hydrochloride monohydrate

The enanti­opure title compound, C₄H₁₀NO₂⁺·Cl⁻·H₂O, forms a two-dimensional network by inter­molecular hydrogen bonding parallel to (010). Non-merohedral twinning with a twofold rotation about the reciprocal c* axis as twin operation was taken into account during intensity integration and structure refinement. This twinning leads to alternative orientations of the stacked hydrogen-bonded layers.

l-Serine methyl ester hydro-chloride

In the enanti-opure crystal of the title compound, C(4)H(10)NO(3) (+)·Cl(-), inter-molecular O-H⋯Cl and N-H⋯Cl hydrogen bonds link the mol-ecules into layers parallel to (001).

Factor B structure provides insights into activation of the central protease of the complement system

Factor B is the central protease of the complement system of immune defense. Here, we present the crystal structure of human factor B at 2.3-A resolution, which reveals how the five-domain proenzyme is kept securely inactive. The canonical activation helix of the Von Willebrand factor A (VWA) domain is displaced by a helix from the preceding domain linker. The two helices conformationally link the scissile-activation peptide and the metal ion-dependent adhesion site required for binding of the ligand C3b. The data suggest that C3b binding displaces the three N-terminal control domains and reshuffles the two central helices. Reshuffling of the helices releases the scissile bond for final proteolytic activation and generates a new interface between the VWA domain and the serine protease domain. This allosteric mechanism is crucial for tight regulation of the complement-amplification step in the immune response.

Structure of Complement Component C2a: Implications for Convertase Formation and Substrate Binding

C2a provides the catalytic center to the convertase complexes of the classical and lectin-binding pathways of complement activation. We determined two crystal structures of full-length C2a, with and without a pseudo ligand bound. Both structures reveal a near-active conformation of the catalytic center of the serine protease domains, while the von Willebrand factor A-type domains display an intermediate activation state of helix alpha7 with an open, activated metal-ion-dependent adhesion site. The open adhesion site likely serves to enhance the affinity for the ligand C4b, similar to "inside-out" signaling in integrins. Surprisingly, the N-terminal residues of C2a are buried in a crevice near helix alpha7, indicative of a structural switch between C2 and C2a. Extended loops on the protease domain possibly envelop the protruding anaphylatoxin domain of the substrate C3. Together with a putative substrate-induced completion of the oxyanion hole, this may contribute to the high substrate specificity of the convertases.

Monitoring of the booster biocide dichlofluanid in water and marine sediment of Greek marinas

Dichlofluanid (N-dichlorofluoromethylthio-N'-dimethyl-N-phenylsulphamide) is used as booster biocide in antifouling paints. The occurrence of dichlofluanid and its metabolite DMSA (N'-dimethyl-N-phenyl-sulphamide) was monitored in seawater and marine sediment from three Greek marinas. Seawater and sediment samples were collected at three representative positions and one suspected hotspot in each marina and shipped to the laboratory for chemical analysis. As part of the project, an analytical method had been developed and validated. Furthermore, some additional experiments were carried out to investigate the potential contribution of paint particle bound dichlofluanid on the total concentration in the sediment. As expected, given its known high hydrolytic degradation rate, no detectable concentrations of dichlofluanid were measured in any of the seawater samples. DMSA was detected in seawater samples at very low concentrations varying from <3 ng l(-1) (LOD) to 36 ng l(-1). During method validation, it had already been demonstrated that dichlofluanid is unstable in sediment and can therefore only be determined as its metabolite DMSA. In a separate experiment, in which marine sediment was spiked with artificial paint particles containing dichlofluanid and then analysed according to the validated method, it was demonstrated that if there is any dichlofluanid originating from paint particles, this would be determined as DMSA. No DMSA was detected in any of the sediment samples. It could therefore be concluded that there were no significant concentrations of dichlofluanid in the sediment samples.

Structure of a Drosophila sigma class glutathione S-transferase reveals a novel active site topography suited for lipid peroxidation products

Insect glutathione-S-transferases (GSTs) are grouped in three classes, I, II and recently III; class I (Delta class) enzymes together with class III members are implicated in conferring resistance to insecticides. Class II (Sigma class) GSTs, however, are poorly characterized and their exact biological function remains elusive. Drosophila glutathione S-transferase-2 (GST-2) (DmGSTS1-1) is a class II enzyme previously found associated specifically with the insect indirect flight muscle. It was recently shown that GST-2 exhibits considerable conjugation activity for 4-hydroxynonenal (4-HNE), a lipid peroxidation product, raising the possibility that it has a major anti-oxidant role in the flight muscle. Here, we report the crystal structure of GST-2 at 1.75A resolution. The GST-2 dimer shows the canonical GST fold with glutathione (GSH) ordered in only one of the two binding sites. While the GSH-binding mode is similar to other GST structures, a distinct orientation of helix alpha6 creates a novel electrophilic substrate-binding site (H-site) topography, largely flat and without a prominent hydrophobic-binding pocket, which characterizes the H-sites of other GSTs. The H-site displays directionality in the distribution of charged/polar and hydrophobic residues creating a binding surface that explains the selectivity for amphipolar peroxidation products, with the polar-binding region formed by residues Y208, Y153 and R145 and the hydrophobic-binding region by residues V57, A59, Y211 and the C-terminal V249. A structure-based model of 4-HNE binding is presented. The model suggest that residues Y208, R145 and possibly Y153 may be key residues involved in catalysis.

Learning and memory of school children with epilepsy: a prospective controlled longitudinal study

The aim of the study was to determine whether learning and memory are compromised in school children with recently diagnosed idiopathic and/or cryptogenic epilepsy and to study relationships between learning and memory and psychosocial and epilepsy variables. Word span and learning of locations were assessed within 48 hours after diagnosis of epilepsy and three and 12 months later, in 69 school children with epilepsy (aged 9.1 years, SD 2.7; 33 males, 36 females) and 66 classmates. Results showed that patients and controls performed similarly in registration, recall, and retention. Patients recalled slightly less than controls when probed under conditions of increased demand on working memory. Maladaptive reactions of parents and children to the onset of epilepsy and not reaching 6-months of seizure remission contributed to poor performance. Individually, those patients who required special assistance at school, under-performed occasionally in one or the other component of memory. Although the proportion of under-performers was stable over time, the children composing the group did change. It was concluded that school children with new onset idiopathic or cryptogenic epilepsy are inordinately vulnerable when processing memory tasks. The vulnerability is neither persistent nor memory-specific.

The structure of phosphatidylinositol transfer protein alpha reveals sites for phospholipid binding and membrane association with major implications for its function

Elucidation of the three-dimensional structure of phosphatidylinositol transfer protein alpha (PI-TPalpha) void of phospholipid revealed a site of membrane association connected to a channel for phospholipid binding. Near the top of the channel specific binding sites for the phosphorylcholine and phosphorylinositol head groups were identified. The structure of this open form suggests a mechanism by which PI-TPalpha preferentially binds PI from a membrane interface. Modeling predicts that upon association of PI-TPalpha with the membrane the inositol moiety of bound PI is accessible from the medium. Upon release from the membrane PI-TPalpha adopts a closed structure with the phospholipid bound fully encapsulated. This structure provides new insights as to how PI-TPalpha may play a role in PI metabolism.

Structure of apo-phosphatidylinositol transfer protein alpha provides insight into membrane association

Phosphatidylinositol transfer protein alpha (PITP alpha) is a ubiquitous and highly conserved protein in multicellular eukaryotes that catalyzes the exchange of phospholipids between membranes in vitro and participates in cellular phospholipid metabolism, signal transduction and vesicular trafficking in vivo. Here we report the three-dimensional crystal structure of a phospholipid-free mouse PITP alpha at 2.0 A resolution. The structure reveals an open conformation characterized by a channel running through the protein. The channel is created by opening the phospholipid-binding cavity on one side by displacement of the C-terminal region and a hydrophobic lipid exchange loop, and on the other side by flattening of the central beta-sheet. The relaxed conformation is stabilized at the proposed membrane association site by hydrophobic interactions with a crystallographically related molecule, creating an intimate dimer. The observed open conformer is consistent with a membrane-bound state of PITP and suggests a mechanism for membrane anchoring and the presentation of phosphatidylinositol to kinases and phospholipases after its extraction from the membrane. Coordinates have been deposited in the Protein Data Bank (accession No. 1KCM).

Attention deficits are not characteristic of schoolchildren with newly diagnosed idiopathic or cryptogenic epilepsy

PURPOSE

To compare problems of attention in schoolchildren with newly diagnosed idiopathic or cryptogenic epilepsy with those in healthy classmates.

METHODS

A computerized battery of tasks comprised Reaction Time (RT) measurement, Trail making (Color Trails 1 and 2), Manual Tapping and Steadiness, and a newly developed task of sustained attention (Balloon Piercing).

SUBJECTS

Fifty-one children with epilepsy (age 7-16 years) and 48 gender- and age-matched classmates were assessed thrice: within 48 h after diagnosis [before start of antiepileptic drugs (AEDs)], and 3 and 12 months later. Significantly more children with epilepsy (51%) than control children (27%) had required special educational assistance at school.

RESULTS

Children with epilepsy could not be distinguished from controls in execution times or motor speed. However, errors were more frequent among patients in a "go-no-go" RT task, and errors of omission in a task requiring sustained attention. Within the group of children with epilepsy, those with prior school or behavior difficulties and those whose parents reacted maladaptively to the onset and diagnosis of epilepsy performed worse than those without these adversities, in the sense that their RT increased inordinately with increasing task difficulty. Epilepsy-related variables did not explain any variance. Transient inordinately poor performances were found in 69% of patients and 40% of controls.

CONCLUSIONS

Children with newly diagnosed "epilepsy only" do not have persistent attention deficits. AED treatment has no detrimental effect on attention. Prior school and behavior difficulties and a maladaptive reaction to the onset of epilepsy rather than epilepsy variables are related to decreased attentional efficiency.

Parents' perceptions of adversity introduced by upheaval and uncertainty at the onset of childhood epilepsy

PURPOSE

We report the parent's perceptions of and reactions to the onset of "epilepsy only" and the implications for continuity of parenting.

METHODS

Content analysis was used to extract data on perceived (dis)continuity of parenting, from interviews held with parents of 69 schoolchildren in whom idiopathic or cryptogenic epilepsy ("epilepsy only") had recently been diagnosed.

RESULTS

Almost half of the parents (42%) perceived neither themselves nor their child as having been thrown off balance by the onset of epilepsy. Quite a few parents (33%) perceived themselves rather than their child as having been thrown off balance. More parents of children with cryptogenic than with idiopathic epilepsy perceived themselves as being off balance. However, parents' perceptions of their children's reactions to the epilepsy-related changes were not influenced by any epilepsy variable. Rather, family trouble, long-standing behavioral problems, and adolescence contributed to the child's maladaptive reaction. Three extremely off-balance parents had children with seizures of "unclassifiable" epilepsy that later were found to be nonepileptic and psychogenic.

CONCLUSIONS

The majority of the parents perceived their child as adapting well to the onset of epilepsy only. Children with seizure onset in adolescence and children with other adversities were perceived as adapting poorly to the additional adversity of epilepsy. Cryptogenic rather than idiopathic etiology leaves parents in great suspense. In behavioral studies, it is advisable to treat children with unclassifiable epilepsy as a separate group.

The structure of leech anti-platelet protein, an inhibitor of haemostasis

Leech anti-platelet protein (LAPP) from the leech Haementeria officinalis is a collagen-binding protein that inhibits the collagen-mediated adhesion of blood platelets. The crystal structure of recombinant LAPP has been determined using single isomorphous replacement with anomalous scattering combined with solvent flattening and threefold molecular averaging. The model of LAPP has been refined to 2.2 A resolution (R factor 21.5%; free R factor 24.0%). LAPP contains an 89-residue C-terminal domain consisting of a central six-stranded antiparallel beta-sheet flanked on one side by an alpha-helix and on the other side by two extended loops with little secondary structure. A 36-residue N-terminal region is not visible in the electron-density map. This region is rich in glycine and lacks hydrophobic residues. It probably does not have a compact globular fold, but instead has an extended conformation and is flexible. The crystal packing suggests that LAPP may form tightly interacting dimers. The fold of the C-terminal domain of LAPP closely resembles that of the N-domain of hepatocyte growth factor (HGF), which classifies LAPP as a PAN domain. However, no significant sequence homology exists between LAPP and other PAN domains. Common structural features between LAPP and the HGF N-domain include two disulfide bonds that link the alpha-helix to the central region of the protein and five residues with a conserved hydrophobic nature that are located in the core of the domain. These conserved structural features may be an important determinant of the PAN-domain type of fold.

Epilepsy-related ambiguity in rating the child behavior checklist and the teacher's report form

Although the child behavior checklist (CBCL) and the teacher's report form (TRF) were not designed for diagnosing psychopathology in children with chronic illnesses, they have become extensively used research tools to assess behavioural problems in paediatric populations, including children with epilepsy. When applied to children with epilepsy, items like "staring blankly" or "twitching" can be rated on the basis of seizure features rather than behaviour and, hence, render behavioural scores ambiguous. The aims were detection, and evaluation of the impact, of CBCL and TRF items eliciting ambiguity when applied to children with "epilepsy only" (idiopathic or cryptogenic epilepsy, attending normal schools). Experts identified items that give rise to interpretational ambiguity of the ratings in epilepsy. By treating ratings on these items as missing values, their effect was evaluated in CBCL and TRF scores of 59 schoolchildren with "epilepsy only" and age and gender matched healthy classmates. Seven items of the CBCL gave rise to ambiguity of which items 5 co-occur on the TRF. Rescoring reduced psychopathology scores in children with "epilepsy only", but not in those of healthy children: the percentage of patients trespassing the clinical cut off score, on at least one of the subscales, reduced from 46 to 23% on the CBCL and from 18 to 15% on the TRF. Parents and teachers run the risk of confusing behaviour and seizure features when filling out the CBCL and TRF. In "epilepsy only", prevalence estimates of psychopathology based on the CBCL and TRF, should be considered with some reserve.

Set-shifting in healthy children and in children with idiopathic or cryptogenic epilepsy

Set-shifting is an important aspect of attention and regulation of behaviour. The ability of young children to shift set is debated. Set-shifting is usually examined using sorting tasks that are designed for adults and hence are inadequate for children. In this study, an experimental Sorting Task for Children (STC) is administered to 54 healthy children (aged 4 to 10 years) and compared with a widely used adult sorting task, the Modified Card Sorting Test. This experiment shows that preschool children are capable of set-shifting. An extensive error analysis of the STC reveals that perseverations are not predominant. Hence, set-shifting in young children may be characterised by 'trial and error' rather than by being stuck in a mental set, which is suggested to be typical of adults with frontal lobe damage. A pilot study of 10 children with idiopathic or cryptogenic epilepsy shows unstable set-shifting rather than inability to shift set, which is concordant with known problems in regulation of behaviour.

Cloning and characterization of a glutathione S-transferase homologue from the plant pathogenic fungus Botrytis cinereadouble dagger

Abstract A gene was cloned from Botrytis cinerea that encodes a protein homologous to glutathione S-transferase (GST). The gene, denominated Bcgst1, is present in a single copy and represents the first example of such a gene from a filamentous fungus. The biochemical function of GSTs is to conjugate toxic compounds to glutathione, thereby detoxifying the compound. In many other organisms, GST plays a role in chemical stress tolerance. We anticipated that GST functions for B. cinerea as a potential virulence factor, enabling the fungus to tolerate fungitoxic plant defence compounds. The expression of Bcgst1 mRNA under various presumably stressful conditions was investigated. Bcgst1 mRNA is expressed at a basal level in liquid cultures and is induced upon addition of hydrogen peroxide to the medium. The level of Bcgst1 mRNA expression during infection of tomato leaves parallels the level of actin mRNA. The role of the Bcgst1 gene in the virulence of Botrytis cinerea was evaluated by constructing gene disruption mutants. Three independent disruption mutants were obtained. The virulence of two mutants on tomato leaves was evaluated. Neither of the mutants showed a decrease in virulence, indicating that the Bcgst1 gene is not essential for virulence on tomato leaves under the conditions tested.

Negative emotions in children with newly diagnosed epilepsy

PURPOSE

To understand the emotional predicament in children with recently diagnosed idiopathic or cryptogenic epilepsy.

METHODS

We used the well-tried method of structured projection for the first time in children with epilepsy. Thirty-six children with epilepsy, aged 7-15 years (mean age, 9.5 years) and in 35 control children aged 7-15 years (mean age, 9.4 years), attributed shame and guilt in relation to three types of situation (non-illness related, illness related, and epilepsy related). Children were evaluated twice: shortly after diagnosis, before antiepileptic drug (AED) use and after an interval of 3 months.

RESULTS

Children with epilepsy and healthy controls were similar in their way of attributing shame and guilt. However, the type of situation was of influence: Both children with epilepsy and healthy children attributed more shame to incompetence due to epilepsy than to incompetence due to other illnesses.

CONCLUSIONS

Increased affective problems in childhood epilepsy cannot be explained by excessive attribution of shame and guilt, affects known to be important precursors of psychopathology, yet both healthy children and children with epilepsy attribute more shame to epilepsy than to other illnesses. Epilepsy is not like any other disease.

Adhesion mechanism of human beta(2)-glycoprotein I to phospholipids based on its crystal structure

Human beta(2)-glycoprotein I is a heavily glycosylated five-domain plasma membrane-adhesion protein, which has been implicated in blood coagulation and clearance of apoptotic bodies from the circulation. It is also the key antigen in the autoimmune disease anti-phospholipid syndrome. The crystal structure of beta(2)-glycoprotein I isolated from human plasma reveals an elongated fish-hook-like arrangement of the globular short consensus repeat domains. Half of the C-terminal fifth domain deviates strongly from the standard fold, as observed in domains one to four. This aberrant half forms a specific phospholipid-binding site. A large patch of 14 positively charged residues provides electrostatic interactions with anionic phospholipid headgroups and an exposed membrane-insertion loop yields specificity for lipid layers. The observed spatial arrangement of the five domains suggests a functional partitioning of protein adhesion and membrane adhesion over the N- and C-terminal domains, respectively, separated by glycosylated bridging domains. Coordinates are in the Protein Data Bank (accession No. 1QUB).

Improving scFv antibody expression levels in the plant cytosol

Expression of single-chain antibody fragments (scFvs) in the plant cytosol is often cumbersome. It was unexpectedly shown that addition at the C-terminus of the ER retention signal KDEL resulted in significantly improved expression levels. In this report the cytosolic location of the scFv-CK was confirmed, excluding possible mistranslocation to other subcellular compartments. It was shown that expression of several other scFvs was also improved in tobacco protoplasts. In addition expression was improved in transgenic potato. Changing from KDEL to KDEI did not affect the enhanced protein expression level. Addition of the KDEL motif is a simple and straightforward tool to stabilize in planta cytosolic expression of many scFvs.

Effect of Brussels sprouts on oxidative DNA-damage in man

The effect of consumption of Brussels sprouts on the excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) into human urine was investigated. Ten non-smoking volunteers (five males and five females) were randomly assigned to two groups. Five volunteers started on a diet of 300 g of glucosinolate-free vegetables whereas the other five consumed 300 g of Brussels sprouts per day. After 1 week dietary regimes were reversed. Levels of 8-oxodG in 24-h urine samples were measured by high-performance liquid chromatography. In four of five males a reduction in 8-oxodG was found, whereas in the fifth male the 8-oxodG excretion was high in the control period and was even much higher in the sprouts period. In females no effect of consumption of Brussels sprouts on excretion of 8-oxodG was found. Our previous and present findings support the results of epidemiologic studies that consumption of brassica vegetables may diminish cancer risk.

Expression and functional characterization of a single chain Fv antibody directed against secretions involved in plant nematode infection process

Expression in plants of antibodies directed against proteins essential for pathogenesis could provide an alternative approach to engineer new resistance traits into crops. Salivary secretions of the root-knot nematode Meloidogyne incognita are known to play a key role during this nematode infection process. From a hybridoma cell line producing an IgM monoclonal antibody specific to these secretions, we have constructed a synthetic gene that encodes an antigen-binding single-chain Fv protein (scFv). The scFv gene was created by polymerase chain reaction amplification of variable domain encoding regions from the IgM antibody. The cloned scFv was initially expressed in Escherichia coli as a 33-kDa protein which could be purified to near homogeneity by immobilized metal affinity chromatography. The produced scFv is fully functional since it shows the same specificity towards a crude extract of M. incognita infective larvae as the corresponding parental IgM. Transient expression assays with tobacco leaf protoplasts using different targeting signals resulted in a high intracellular accumulation of scFv, especially when fused to the tetrapeptide KDEL retention signal. Activity analysis and stability characterization of this scFv in tobacco protoplast represent the first step before plant transformation in order to test a new form of resistance to root-knot nematode in plants.

The C-terminal KDEL sequence increases the expression level of a single-chain antibody designed to be targeted to both the cytosol and the secretory pathway in transgenic tobacco

The effects of subcellular localization on single-chain antibody (scFv) expression levels in transgenic tobacco was evaluated using an scFv construct of a model antibody possessing different targeting signals. For translocation into the secretory pathway a secretory signal sequence preceded the scFv gene (scFv-S). For cytosolic expression the scFv antibody gene lacked such a signal sequence (scFv-C). Also, both constructs were provided with the endoplasmic reticulum (ER) retention signal KDEL (scFv-SK and scFv-CK, respectively). The expression of the different scFv constructs in transgenic tobacco plants was controlled by a CaMV 35S promoter with double enhancer. The scFv-S and scFv-SK antibody genes reached expression levels of 0.01% and 1% of the total soluble protein, respectively. Surprisingly, scFv-CK transformants showed considerable expression of up to 0.2% whereas scFv-C transformants did not show any accumulation of the scFv antibody. The differences in protein expression levels could not be explained by the steady-state levels of the mRNAs. Transient expression assays with leaf protoplasts confirmed these expression levels observed in transgenic plants, although the expression level of the scFv-S construct was higher. Furthermore, these assays showed that both the secretory signal and the ER retention signal were recognized in the plant cells. The scFv-CK protein was located intracellularly, presumably in the cytosol. The increase in scFv protein stability in the presence of the KDEL retention signal is discussed.

Peptides containing the sulfonamide transition-state isostere: synthesis and structure of N-acetyl-tauryl-L-proline methylamide

The structure of the sulfonamide isostere-containing peptide N-acetyl-tauryl-proline methylamide 4 was compared to information on the structure of the peptide N-acetyl-beta-alanyl-proline methylamide 6. NMR measurements of the beta-alanine containing peptide 6 showed the presence of two conformations due to cis/trans isomerism of the beta-Ala-Pro amide bond, whereas the sulfonamide-containing peptide 4 appeared in only one conformation. The crystal structure of N-acetyl-tauryl-proline methylamide 4 gave additional evidence for the absence of cis/trans isomerism. The crystals are orthorhombic, space group P2(1)2(1)2(1), Z = 4, F(000) = 592, a = 7.5919(3), b = 10.3822(2), c = 17.1908(7) A, V = 1354.99(8) A3, Dx = 1.359 g cm-3. The oxygen atoms connected to the sulfur take positions similar to both the cis and trans positions of the carbonyl oxygen of an amide. Consequently the tauryl part is placed perpendicular to the proline alpha-C-C(O) bond, giving it an extended conformation in contrast to the cis/trans isomers of N-acetyl-beta-alanyl-proline methylamide 6.

Antimutagenicity of eugenol in the rodent bone marrow micronucleus test

The antimutagenic effect of eugenol on the mutagenicity of cyclophosphamide (CP), mitomycin C (MMC), ethyl methanesulfonate (EMS) and benzo[a]pyrene (B[a]P) was assessed in the rodent bone marrow micronucleus test using male Swiss mice. Oral administration of eugenol (0.4% in the diet) for 15 days was found to decrease significantly the frequency of micronucleated polychromatic erythrocytes (MPEs) elevated by CP. No effect was found on the frequency of MPEs elevated by MMC, EMS and B[a]P. The results provide some support for antimutagenic potency of eugenol in vivo.

Contents of methyl-, ethyl-, propyl-, butyl- and benzylparaben in cosmetic products

The contents of methyl-, ethyl-, propyl-, butyl- and benzylparaben in 215 cosmetic products have been determined to elucidate the concentration and frequency of use of these parabens in cosmetic products, and to monitor whether the products complied with the Danish and EEC regulations. The results showed that 77% of the products investigated contained 0.01%-0.87% parabens. Nearly all (99%) of the leave-on cosmetics and 77% of rinse-off cosmetics were found to contain parabens. A maximum of 0.32% methyl- and propylparaben, 0.19% ethylparaben, and 0.07% butyl- and benzylparaben were present in paraben-positive cosmetics. A preferential use of methyl-/ethyl-/propyl-/butyl-/benzylparaben in various groups of cosmetic products was revealed.

Coordinate expression of antibody subunit genes yields high levels of functional antibodies in roots of transgenic tobacco

To explore the feasibility of employing antibodies to obtain disease resistance against plant root pathogens, we have studied the expression of genes encoding antibodies in roots of transgenic plants. A model monoclonal antibody was used that binds to a fungal cutinase. Heavy and light chain cDNAs were amplified by PCR, fused to a signal sequence for secretion and cloned behind CaMV 35S and TR2' promoters in a single T-DNA. The chimeric genes were cloned both in tandem and in a divergent orientation. The roots of tobacco plants transformed with these constructs produced antibodies that were able to bind antigen in an ELISA. Immunoblotting showed assembly to a full-size antibody. In addition, a F(ab')2-like fragment was observed, which is probably formed by proteolytic processing. Both antibody species were properly targeted to the apoplast, but the full-size antibody was partially retained by the wall of suspension cells. The construct with divergent promoters showed a better performance than the construct with promoters in tandem. It directed the accumulation of functional antibodies to a maximum of 1.1% of total soluble protein, with half of the plants having levels higher than 0.35%. The high efficiency of this construct probably results from coordinated and balanced expression of light and heavy chain genes, as evidenced by RNA blot hybridization.

[Peroperative anaphylactic reactions due to latex allergy]

A 10-year-old girl with spina bifida underwent surgery to increase the capacity of her neurogenic bladder using an isolated loop of intestine. During the operation serious circulatory and respiratory problems occurred after the peritoneum was opened, when the ileum was manipulated using gloves containing latex. Latex allergy can lead to potentially fatal anaphylactic reactions. A survey is presented of the risk groups, together with measures recently advocated in the literature to detect latex allergy and to avoid major reactions.

2′-O-Methyl-cis-adenosine 3′,5′-cyclic methyl monophosphate, a new model system for cAMP. Aspects of structure and reactivity

This study is focussed on 2′-O-methyl-cis-adenosine 3′,5′-cyclic methyl monophosphate (cis-4; cis describes the relationship between OMe (bound to phosphorus) and the adenine base), which is regarded a model for enzyme-bound cyclic adenosine monophosphate (cAMP). In this complex the negative phosphate charge is shielded in part via complexation with cationic sites on the enzyme surface. We report synthesis, crystal structure, solution conformation (400 MHz 1H NMR), and kinetic-mechanistic aspects of the alkaline hydrolysis of cis-4. The methanol solvate of cis-4 crystallizes in the orthorhombic space group P212121 and the cell dimensions are a = 8.170(2) Å, b = 9.249(1) Å, c = 23.699(4) Å; V = 1788.5(6) Å3; Z = 4 molecules per cell. Least-squares refinement converged at R = 0.062 for 2006 observed reflections. The adenine bases are linked via [Formula: see text] and [Formula: see text] hydrogen bonds in such a way that infinite one-dimensional chains are formed. This hydrogen bond scheme is very similar to that observed in the structure of 2′-deoxy-3′,5′-di-O-acetyl adenosine. An additional hydrogen bond is formed between methanol, incorporated in the crystal structure, and the adenine base. The conformational preferences of the cis-4 dissolved in methanol have been determined with 400 MHz 1H NMR. It is found that the conformations observed in the solid and solution states are practically the same. Hydrolysis of the title compound yields two acyclic phosphate diesters (a 3′- and a 5′-phosphate diester). The intermediates formed during the hydrolysis reaction are most likely five-coordinated phosphorus (PV) compounds with a trigonal bipyramidal geometry and an equatorial-axial located 3′,5′-dioxaphosphorinane ring.