bluuebunny/crossref_metadata_2025 huggingface dataset:
New safety margins for chin bone harvesting based on the course of the mandibular incisive canal in CT
Authors: Pommer Bernhard , Tepper Gabor , Gahleitner André , Zechner Werner , Watzek Georg
Published: November 2008

Objectives: Altered pulp sensitivity of anterior lower teeth is a frequent finding following chin bone harvesting. Persistent loss of tooth sensitivity has been reported in up to 20% of the patients. The aim of this study was to evaluate current recommendations for the location of the harvest zone with respect to the course of the mandibular incisive canal (MIC), the intrabony continuation of the mandibular canal mesial to the mental foramen.

Material and methods: On computed tomographic (CT) scans of 50 dentate mandibles, the MIC was located and its distance to the root apices, to the labial bony surface, and to the inferior margin of the mandible was assessed. The risk of nerve injury and the percentage of patients suitable for chin bone grafting were calculated.

Results: Respecting current recommendations for chin bone grafting, the content of the MIC was endangered in 57% of the CTs. Therefore, new safety margins are suggested: the chin bone should be harvested at least 8 mm below the tooth apices with a maximum harvest depth of 4 mm.

Conclusions: Applying the new safety recommendations and proper patient selection in chin bone harvesting could reduce the risk of altered postoperative tooth sensitivity due to injury of the mandibular incisive nerve.
Optimisation of the hydrogen peroxide pre‐treatment of titanium: surface characterisation and protein adsorption
Authors: Nagassa M. E. , Daw A. E. , Rowe W. G. , Carley A. , Thomas D. W. , Moseley R.
Published: November 2008

Background: Researchers have attempted to enhance titanium osseointegration by modifying its surface properties, including via H2O2 pre‐treatment, with reported treatment regimes varying from minutes/hours, to weeks.

Objective: This study examined the effects of various H2O2 treatments on titanium surface topography/roughness, chemical composition/oxide thickness, hydrophilicity and plasma protein adsorption.

Materials and methods: Titanium discs were treated with 30% H2O2 for 0–24 h or 1–4 weeks and subjected to atomic force microscopy (AFM), scanning electron microscopy (SEM), profilometry, X‐ray photon spectroscopy and contact angle analysis. For protein adsorption, whole plasma and FITC‐conjugated serum albumin were added to 0–24 h and  1–4 week H2O2‐treated discs and examined by SEM and fluorescence microscopy, respectively.

Results: AFM, SEM and profilometry demonstrated that 1–6 h H2O2‐treated discs exhibited subtle alterations in surface topography/roughness at the nanometre scale, although 24 h and 1–4 week H2O2‐treated discs exhibited much greater increases in surface roughness, in the micrometre range. Maximal increases in surface oxide thickness and chemical modification were identified between 1 h–4 weeks and 3 h–4 weeks, respectively, although no increases in oxygen/titanium (O1s : Ti2p) molar ratio or in hydrophilicity were evident. Plasma and serum albumin adsorption increased on 1–24 h H2O2‐treated discs, with further increases on 1–4 week H2O2‐treated discs.

Conclusions: Based upon the present data and previous findings, this study supports the concept that surface topography/roughness and oxide composition/thickness, are more significantly modified by H2O2 treatment and more influential to protein adsorption than hydrophilicity. Additionally, it can be hypothesized that the 24 h H2O2 treatment of titanium surfaces, which induced micrometre scale changes in roughness and protein adsorption, to those associated with enhanced osteoblast attachment/behaviour, mineralisation and subsequent implant osseointegration, would be most beneficial.
Periodontal ligament cell sheet promotes periodontal regeneration in athymic rats
Authors: Flores Mara Gomez , Yashiro Reiko , Washio Kaoru , Yamato Masayuki , Okano Teruo , Ishikawa Isao
Published: November 2008

Aim: The primary goal of periodontal treatment is regeneration of the periodontium. Current theories suggest that the periodontal ligament (PDL) cells have the capacity to participate in restoring connective and mineralized tissues, when appropriately triggered. We evaluated whether human PDL cell sheets could reconstruct periodontal tissue.

Material and Methods: To obtain the cell sheet, human PDL cells were cultured on temperature‐responsive culture dishes with or without osteogenic differentiation medium. The cell sheets were transplanted on periodontal fenestration defects of immunodeficient rats. Forty rats were divided in two groups: in one group, cell sheets cultured with control medium were transplanted and in the other, cell sheets cultured with osteogenic differentiation medium were transplanted. The defects were analysed histologically and histomorphologically after healing.

Results: Most of the experimental group exhibited a new cementum‐like layer and new attachment of collagen fibres to the layer. Histomorphological analyses indicated significant periodontal regeneration. The control group revealed dense extracellular matrix and fibre formation, but an obvious cementum layer was not observed.

Conclusions: Transplanted PDL cell sheets cultured with osteogenic differentiation medium induced periodontal regeneration containing an obvious cementum layer and Sharpey's fibres. Thus, the method could be feasible as a new therapeutic approach for periodontal regeneration.
Replacement therapy for periodontitis: pilot radiographic evaluation in a dog model
Authors: Nackaerts Olivia , Jacobs Reinhilde , Quirynen Marc , Rober Marleen , Sun Yi , Teughels Wim
Published: November 2008

Aim: The aim of this study was to radiologically evaluate the impact of replacement therapy by monitoring bone density changes and alveolar bone level in periodontal pockets in a dog model.

Material and Methods: Eight male beagle dogs with moderate periodontitis were enrolled in this split‐mouth, double‐blind randomized trial with ethical approval. Periodontal defects were surgically created bilaterally in the lower jaw. Four months later, the defects were randomly assigned to initial therapy (scaling and root planing) alone (control sites), or combined with multiple subgingival application of beneficial species. Intra‐oral follow‐up radiography was performed at this stage and 3 months later to verify the treatment effect.

Results: The bone density within periodontal pockets treated with beneficial bacteria improved significantly after 12 weeks, while this was non‐significant for the control pockets, receiving a single root planing at baseline. There was a significant increase in the bone level at the end of the study for the pockets receiving beneficial bacteria. Again, no significance was noted for the control pockets.

Conclusions: This pilot study indicates the potential effect of a subgingival application of beneficial species in periodontal pockets, and illustrates the strength of standardized follow‐up radiography to evaluate the effects of different treatment strategies on bone re‐modelling.
TLR4 and IL‐18 gene variants in aggressive periodontitis
Authors: Noack Barbara , Görgens Heike , Lorenz Katrin , Ziegler Andreas , Hoffmann Thomas , Schackert Hans Konrad
Published: November 2008

Aim: We aimed to assess the association of different genotypes with increased aggressive periodontitis susceptibility by studying functional relevant variants in the pathogen‐recognition receptor Toll‐like receptor 4 (TLR4) and variants in the promoter region of the pro‐inflammatory cytokine interleukin‐18 (IL‐18).

Material and Methods: One hundred and eleven patients with aggressive periodontitis and 80 periodontally healthy controls were genotyped for four functional variants in the TLR4 gene (c.896A>G and c.1196C>T) and in the IL‐18 promoter (c.−368G>C and c.−838C>A). The genotype and allele frequencies, as well as the frequency of combined genotypes were compared between study groups.

Results: There were no statistical differences in genotype and allele frequencies within the four variants between the groups. All study subjects were further classified into carriers and non‐carriers of at least one variant of both genes. The logistic regression analysis adjusted for gender and smoking showed no association between carrier status of at least one variant of both genes and periodontal status (OR=1.41, 95% CI: 0.43–4.70).

Conclusions: Our results reject the hypothesis that functionally relevant IL‐18 and TLR4 gene mutations have a major effect on aggressive periodontitis susceptibility alone or in combination.
The skin: an indispensable barrier
Authors: Proksch Ehrhardt , Brandner Johanna M. , Jensen Jens‐Michael
Published: November 2008

Abstract:  The skin forms an effective barrier between the organism and the environment preventing invasion of pathogens and fending off chemical and physical assaults, as well as the unregulated loss of water and solutes. In this review we provide an overview of several components of the physical barrier, explaining how barrier function is regulated and altered in dermatoses. The physical barrier is mainly localized in the stratum corneum (SC) and consists of protein‐enriched cells (corneocytes with cornified envelope and cytoskeletal elements, as well as corneodesmosomes) and lipid‐enriched intercellular domains. The nucleated epidermis also contributes to the barrier through tight, gap and adherens junctions, as well as through desmosomes and cytoskeletal elements. During epidermal differentiation lipids are synthesized in the keratinocytes and extruded into the extracellular domains, where they form extracellular lipid‐enriched layers. The cornified cell envelope, a tough protein/lipid polymer structure, resides below the cytoplasmic membrane on the exterior of the corneocytes. Ceramides A and B are covalently bound to cornified envelope proteins and form the backbone for the subsequent addition of free ceramides, free fatty acids and cholesterol in the SC. Filaggrin is cross‐linked to the cornified envelope and aggregates keratin filaments into macrofibrils. Formation and maintenance of barrier function is influenced by cytokines, 3′,5′‐cyclic adenosine monophosphate and calcium. Changes in epidermal differentiation and lipid composition lead to a disturbed skin barrier, which allows the entry of environmental allergens, immunological reaction and inflammation in atopic dermatitis. A disturbed skin barrier is important for the pathogenesis of contact dermatitis, ichthyosis, psoriasis and atopic dermatitis.
Density dependent and temporal variability in habitat selection by a large herbivore; an experimental approach
Authors: Mobæk Ragnhild , Mysterud Atle , Egil Loe Leif , Holand Øystein , Austrheim Gunnar
Published: November 2008

Both density dependent and density independent processes such as climate affect population dynamics in large herbivores. Understanding herbivore foraging patterns is essential to identify the underlying mechanisms behind variation in vital rates. However, very little is known about how animals vary their selection of habitat temporally, alone or in interaction with density during summer. At the foraging scale, we tested using a fully replicated experiment whether domestic sheep Ovis aries stocked at high (80 per km2) and low (25 per km2) densities (spatial contrasts) varied their habitat selection temporally over a four year period. We predicted reduced selection of high productivity vegetation types with increasing density, and that seasonal and annual variation in climate would affect this density dependent selection pattern by increasing competition for high quality habitats in late grazing season and in years with poor vegetation development and over time related to vegetation responses to grazing. As predicted from the Ideal free distribution model, selection of high productivity habitat decreased at high density. There was also a marked temporal variation in habitat selection. Selection of the most productive vegetation types declined towards the end of each grazing season, but increased over years both at low and high sheep density. There was only weak evidence for interactions, as selection ratio of highly productive habitats tended to increase more over years at low density as compared to high density. Limited interactive effects of density and annual variation on habitat selection during summer may explain why similar interactions in vital rates have rarely been reported for summer seasons. Our results are consistent with the view that variation in habitat selection is a central mechanism for climate and density related variation in vital rates.
Does the mode of transmission between hosts affect the host choice strategies of parasites? Implications from a field study on bat fly and wing mite infestation of Bechstein's bats
Authors: Reckardt Karsten , Kerth Gerald
Published: November 2008

In a two‐year field study, we analyzed the distribution of two hematophagous ectoparasites, the bat flyBasilia nanaand the wing miteSpinturnix bechsteini, within and among 14 female colonies and among 26 solitary male Bechstein's batsMyotis bechsteinii. Our goal was to investigate whether differences in the transmission mode of the parasites, which result from differences in their life cycle, affect their distribution between host colonies and among host individuals within colonies. Bat flies deposit puparia in bat roosts, allowing for the transmission of hatched flies via successively shared roosts, independent of body contact between hosts or of hosts occupying a roost at the same time. In contrast, wing mites stay on the bat's body and are transmitted exclusively by contact of bats that roost together. As expected in cases of higher inter‐colony transmissibility, bat flies were more prevalent among the demographically isolated Bechstein's bat colonies and among solitary male bats, as compared to wing mites. Moreover, the prevalence and density of wing mites, but not of bat flies, was positively correlated with colony size, as expected in cases of low inter‐colony transmissibility. Within colonies, bat flies showed higher abundance on host individuals in good body condition, which are likely to have high nutritional status and strong immunity. Wing mites showed higher abundance on hosts in medium body condition and on reproductive females and juveniles, which are likely to have relatively weak immunity. We suggest that the observed infestation patterns within host colonies reflect different host choice strategies of bat flies and wing mites, which may result from differences in their inter‐colony transmissibility. Our data also indicate that infestation with wing mites, but not with bat flies, might be a cost of sociality in Bechstein's bats.
Propagule pressure and resource availability determine plant community invasibility in a temperate forest understorey
Authors: Tanentzap Andrew J. , Bazely Dawn R.
Published: November 2008

Few field experiments have examined the effects of both resource availability and propagule pressure on plant community invasibility. Two non‐native forest species, a herb and a shrub (Hesperis matronalisandRhamnus cathartica, respectively), were sown into 60 1‐m2sub‐plots distributed across three plots. These contained reconstructed native plant communities in a replaced surface soil layer in a North American forest interior. Resource availability and propagule pressure were manipulated as follows: understorey light level (shaded/unshaded), nutrient availability (control/fertilized), and seed pressures of the two non‐native species (control/low/high).HesperisandRhamnuscover and the above‐ground biomass ofHesperiswere significantly higher in shaded sub‐plots and at greater propagule pressures. Similarly, the above‐ground biomass ofRhamnuswas significantly increased with propagule pressure, although this was a function of density. In contrast, of species that seeded into plots from the surrounding forest during the growing season, the non‐native species had significantly greater cover in unshaded sub‐plots. Plants in these unshaded sub‐plots were significantly taller than plants in shaded sub‐plots, suggesting a greater fitness. Total and non‐native species richness varied significantly among plots indicating the importance of fine‐scale dispersal patterns. None of the experimental treatments influenced native species. Since the forest seed bank in our study was colonized primarily by non‐native ruderal species that dominated understorey vegetation, the management of invasions by non‐native species in forest understoreys will have to address factors that influence light levels and dispersal pathways.
Objective measurement of periocular pigmentation
Authors: Lee Janet Agnes , Osmanovic Smajo , Viana Marlos A. G. , Kapur Rashmi , Meghpara Beeran , Edward Deepak P.
Published: November 2008

Purpose: To evaluate the Minolta CR‐400 chromameter in objectively measuring periocular/facial pigmentation in subjects of different ethnicities.

Methods: The CR‐400 was used to obtain skin color measurements from 75 African‐American, Caucasian and Hispanic subjects in 16 facial and periocular locations. Comparisons between ethnic and Fitzpatrick groups and instrument reliability were analyzed.

Results: Significant differences in L* were observed among all three ethnic groups, while values a* and b* were less sensitive to differences in pigmentation. Comparison between Fitzpatrick groups again identified value L* as being the most sensitive, demonstrating significant differences between the more heavily pigmented groups. The 16 facial locations measured were found to be statistically similar to each other, and the chromameter demonstrated excellent inter‐ and intra‐instrument reliability.

Conclusions: The Minolta CR‐400 chromameter reliably measures facial pigmentation and can be useful for studies evaluating changes in skin pigmentation. Value L* is the parameter that is most sensitive to differences between ethnic and Fitzpatrick groups. Overlap between groups was observed, demonstrating that in future studies, each individual must serve as their own control when monitoring changes in pigmentation. The similarity between all the locations tested demonstrates uniformity of facial pigmentation within an individual.
Sun protection factor persistence during a day with physical activity and bathing
Authors: Bodekær Mette , Faurschou Annesofie , Philipsen Peter Alshede , Wulf Hans Christian
Published: November 2008

Background/purpose: The persistence of sunscreens during a day with physical activity and bathing is often debated. We wished to examine the durability of the protection achieved by one sunscreen application.

Methods: Seven areas were marked on the back of 24 volunteers. One area was phototested to determine UV sensitivity. Six areas were treated with either an organic or an inorganic sunscreen (2 mg/cm2). The participants performed physical activities, were exposed to a hot environment and bathing during 8 h and were phototested with ultraviolet‐B (UVB) radiation 30 min, 4 and 8 h after sunscreen application. The minimal erythema dose (MED) was determined 24 h after irradiation. The sun protection factor (SPF) was calculated, as MED on protected skin/MED on unprotected skin.

Results: The SPFs of the inorganic and organic sunscreen, respectively, were reduced by 38% and 41% after 4 h and by 55% and 58% after 8 h.

Conclusion: One application of either an inorganic or an organic sunscreen reduced the erythema caused by UVB during a day with physical activity and bathing. After 8 h the sunscreens still provided approximately 43% of the initial protective effect. This might simulate what happens during a day at the beach.
Riboflavin‐mediated cellular photoinhibition of cisplatin‐induced oxidative DNA breakage in mice epidermal keratinocytes
Authors: Husain Eram , Naseem Imrana
Published: November 2008

Background/purpose: Cisplatin is one of the most effective chemotherapeutic agents used in the treatment of various kinds of malignant tumors. A major drawback associated with cisplatin chemotherapy is its cytotoxicity/genotoxicity towards normal tissues. The cytotoxicity has been attributed, in part, to the oxidative stress generated by the drug. Riboflavin is a micronutrient known for its photosensitization characteristics. Owing to the emergence of photodynamic therapy as a modality for the treatment of solid tumors and other accessible lesions in terms of opthalmic, dermatological, cardiovascular and urological diseases, the therapeutic window of riboflavin as a sensitizer has been used to avoid the toxic side effects of cisplatin.

Methods & results: Using mice epidermal keratinocytes and comet assay, we show that photochemically activated riboflavin is able to prevent oxidative cellular DNA breakage induced by cisplatin. Irradiation of cells exposed to cisplatin resulted in a dose‐dependent increase in the frequency of strand breaks in cellular DNA. Sequential incubation of keratinocytes with riboflavin and cisplatin followed by irradiation led to a significant decrease in strand breakage and reduced the generation of reactive oxygen species.

Conclusion: Our results suggest that cisplatin‐induced genotoxicity may be blunted or reduced by using riboflavin as a photosensitizer.
Increased anxiety‐like behavior in mice lacking the inhibitory synapse cell adhesion molecule neuroligin 2
Authors: Blundell J. , Tabuchi K. , Bolliger M. F. , Blaiss C. A. , Brose N. , Liu X. , Südhof T. C. , Powell C. M.
Published: November 2008

Neuroligins (NL) are postsynaptic cell adhesion molecules that are thought to specify synapse properties. Previous studies showed that mutant mice carrying an autism‐associated point mutation in NL3 exhibit social interaction deficits, enhanced inhibitory synaptic function and increased staining of inhibitory synaptic puncta without changes in overall inhibitory synapse numbers. In contrast, mutant mice lacking NL2 displayed decreased inhibitory synaptic function. These studies raised two relevant questions. First, does NL2 deletion impair inhibitory synaptic function by altering the number of inhibitory synapses, or by changing their efficacy? Second, does this effect of NL2 deletion on inhibition produce behavioral changes? We now show that although NL2‐deficient mice exhibit an apparent decrease in number of inhibitory synaptic puncta, the number of symmetric synapses as determined by electron microscopy is unaltered, suggesting that NL2 deletion impairs the function of inhibitory synapses without decreasing their numbers. This decrease in inhibitory synaptic function in NL2‐deficient mice correlates with a discrete behavioral phenotype that includes a marked increase in anxiety‐like behavior, a decrease in pain sensitivity and a slight decrease in motor co‐ordination. This work confirms that NL2 modulates inhibitory synaptic function and is the first demonstration that global deletion of NL2 can lead to a selective behavioral phenotype.
Structural and mutational analyses of protein–protein interactions between transthyretin and retinol‐binding protein
Authors: Zanotti Giuseppe , Folli Claudia , Cendron Laura , Alfieri Beatrice , Nishida Sonia K. , Gliubich Francesca , Pasquato Nicola , Negro Alessandro , Berni Rodolfo
Published: November 2008

Transthyretin is a tetrameric binding protein involved in the transport of thyroid hormones and in the cotransport of retinol by forming a complex in plasma with retinol‐binding protein. In the present study, we report the crystal structure of a macromolecular complex, in which human transthyretin, human holo‐retinol‐binding protein and a murine anti‐retinol‐binding protein Fab are assembled according to a 1 : 2 : 2 stoichiometry. The main interactions, both polar and apolar, between retinol‐binding protein and transthyretin involve the retinol hydroxyl group and a limited number of solvent exposed residues. The relevance of transthyretin residues in complex formation with retinol‐binding protein has been examined by mutational analysis, and the structural consequences of some transthyretin point mutations affecting protein–protein recognition have been investigated. Despite a few exceptions, in general, the substitution of a hydrophilic for a hydrophobic side chain in contact regions results in a decrease or even a loss of binding affinity, thus revealing the importance of interfacial hydrophobic interactions and a high degree of complementarity between retinol‐binding protein and transthyretin. The effect is particularly evident when the mutation affects an interacting residue present in two distinct subunits of transthyretin participating simultaneously in two interactions with a retinol‐binding protein molecule. This is the case of the amyloidogenic I84S replacement, which abolishes the interaction with retinol‐binding protein and is associated with an altered retinol‐binding protein plasma transport in carriers of this mutation. Remarkably, some of the residues in mutated human transthyretin that weaken or abolish the interaction with retinol‐binding protein are present in piscine transthyretin, consistent with the lack of interaction between retinol‐binding protein and transthyretin in fish.
Glutamic acid residues in the C‐terminal extension of small heat shock protein 25 are critical for structural and functional integrity
Authors: Morris Amie M. , Treweek Teresa M. , Aquilina J. A. , Carver John A. , Walker Mark J.
Published: November 2008

Small heat shock proteins (sHsps) are intracellular molecular chaperones that prevent the aggregation and precipitation of partially folded and destabilized proteins. sHsps comprise an evolutionarily conserved region of 80–100 amino acids, denoted the α‐crystallin domain, which is flanked by regions of variable sequence and length: the N‐terminal domain and the C‐terminal extension. Although the two domains are known to be involved in the organization of the quaternary structure of sHsps and interaction with their target proteins, the role of the C‐terminal extension is enigmatic. Despite the lack of sequence similarity, the C‐terminal extension of mammalian sHsps is typically a short, polar segment which is unstructured and highly flexible and protrudes from the oligomeric structure. Both the polarity and flexibility of the C‐terminal extension are important for the maintenance of sHsp solubility and for complexation with its target protein. In this study, mutants of murine Hsp25 were prepared in which the glutamic acid residues in the C‐terminal extension at positions 190, 199 and 204 were each replaced with alanine. The mutants were found to be structurally altered and functionally impaired. Although there were no significant differences in the environment of tryptophan residues in the N‐terminal domain or in the overall secondary structure, an increase in exposed hydrophobicity was observed for the mutants compared with wild‐type Hsp25. The average molecular masses of the E199A and E204A mutants were comparable with that of the wild‐type protein, whereas the E190A mutant was marginally smaller. All mutants displayed markedly reduced thermostability and chaperone activity compared with the wild‐type. It is concluded that each of the glutamic acid residues in the C‐terminal extension is important for Hsp25 to act as an effective molecular chaperone.
Secondary structure of lipidated Ras bound to a lipid bilayer
Authors: Güldenhaupt Jörn , Adigüzel Yekbun , Kuhlmann Jürgen , Waldmann Herbert , Kötting Carsten , Gerwert Klaus
Published: November 2008

Ras proteins are small guanine nucleotide binding proteins that regulate many cellular processes, including growth control. They undergo distinct post‐translational lipid modifications that are required for appropriate targeting to membranes. This, in turn, is critical for Ras biological function. However, most in vitro studies have been conducted on nonlipidated truncated forms of Ras proteins. Here, for the first time, attenuated total reflectance‐FTIR studies of lipid‐modified membrane‐bound N‐Ras are performed, and compared with nonlipidated truncated Ras in solution. For these studies, lipidated N‐Ras was prepared by linking a farnesylated and hexadecylated N‐Ras lipopeptide to a truncated N‐Ras protein (residues 1–181). It was then bound to a 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine bilayer tethered on an attenuated total reflectance crystal. The structurally sensitive amide I absorbance band in the IR was detected and analysed to determine the secondary structure of the protein. The NMR three‐dimensional structure of truncated Ras was used to calibrate the contributions of the different secondary structural elements to the amide I absorbance band of truncated Ras. Using this novel approach, the correct decomposition was selected from several possible solutions. The same parameter set was then used for the membrane‐bound lipidated Ras, and provided a reliable decomposition for the membrane‐bound form in comparison with truncated Ras. This comparison indicates that the secondary structure of membrane‐bound Ras is similar to that determined for the nonlipidated truncated Ras protein for the highly conserved G‐domain. This result validates the multitude of investigations of truncated Ras without anchor in vitro. The novel attenuated total reflectance approach opens the way for detailed studies of the interaction network of the membrane‐bound Ras protein.
Phosphorylation of the Saccharomyces cerevisiae Grx4p glutaredoxin by the Bud32p kinase unveils a novel signaling pathway involving Sch9p, a yeast member of the Akt / PKB subfamily
Authors: Peggion Caterina , Lopreiato Raffaele , Casanova Elena , Ruzzene Maria , Facchin Sonia , Pinna Lorenzo A. , Carignani Giovanna , Sartori Geppo
Published: November 2008

The Saccharomyces cerevisiae atypical protein kinase Bud32p is a member of the nuclear endopeptidase‐like, kinase, chromatin‐associated/kinase, endopeptidase‐like and other protein of small size (EKC/KEOPS) complex, known to be involved in the control of transcription and telomere homeostasis. Complex subunits (Pcc1p, Pcc2p, Cgi121p, Kae1p) represent, however, a small subset of the proteins able to interact with Bud32p, suggesting that this protein may be endowed with additional roles unrelated to its participation in the EKC/KEOPS complex. In this context, we investigated the relationships between Bud32p and the nuclear glutaredoxin Grx4p, showing that it is actually a physiological substrate of the kinase and that Bud32p contributes to the full functionality of Grx4p in vivo. We also show that this regulatory system is influenced by the phosphorylation of Bud32p at Ser258, which is specifically mediated by the Sch9p kinase [yeast homolog of mammalian protein kinase B (Akt/PKB)]. Notably, Ser258 phosphorylation of Bud32p does not alter the catalytic activity of the protein kinase per se, but positively regulates its ability to interact with Grx4p and thus to phosphorylate it. Interestingly, this novel signaling pathway represents a function of Bud32p that is independent from its role in the EKC/KEOPS complex, as the known functions of the complex in the regulation of transcription and telomere homeostasis are unaffected when the cascade is impaired. A similar relationship has already been observed in humans between Akt/PKB and p53‐related protein kinase (Bud32p homolog), and could indicate that this pathway is conserved throughout evolution.
Purification and characterization of zebrafish hatching enzyme – an evolutionary aspect of the mechanism of egg envelope digestion
Authors: Sano Kaori , Inohaya Keiji , Kawaguchi Mari , Yoshizaki Norio , Iuchi Ichiro , Yasumasu Shigeki
Published: November 2008

There are two hatching enzyme homologues in the zebrafish genome: zebrafish hatching enzyme ZHE1 and ZHE2. Northern blot and RT‐PCR analysis revealed that ZHE1 was mainly expressed in pre‐hatching embryos, whereas ZHE2 was rarely expressed. This was consistent with the results obtained in an experiment conducted at the protein level, which demonstrated that one kind of hatching enzyme, ZHE1, was able to be purified from the hatching liquid. Therefore, the hatching of zebrafish embryo is performed by a single enzyme, different from the finding that the medaka hatching enzyme is an enzyme system composed of two enzymes, medaka high choriolytic enzyme (MHCE) and medaka low choriolytic enzyme (MLCE), which cooperatively digest the egg envelope. The six ZHE1‐cleaving sites were located in the N‐terminal regions of egg envelope subunit proteins, ZP2 and ZP3, but not in the internal regions, such as the ZP domains. The digestion manner of ZHE1 appears to be highly analogous to that of MHCE, which partially digests the egg envelope and swells the envelope. The cross‐species digestion using enzymes and substrates of zebrafish and medaka revealed that both ZHE1 and MHCE cleaved the same sites of the egg envelope proteins of two species, suggesting that the substrate specificity of ZHE1 is quite similar to that of MHCE. However, MLCE did not show such similarity. Because HCE and LCE are the result of gene duplication in the evolutionary pathway of Teleostei, the present study suggests that ZHE1 and MHCE maintain the character of an ancestral hatching enzyme, and that MLCE acquires a new function, such as promoting the complete digestion of the egg envelope swollen by MHCE.
Enhancer requirement for histone methylation linked with gene activation
Authors: Rentoft Matilda , Kim Kihoon , Cho Youngran , Lee Choon‐Hwan , Kim AeRi
Published: November 2008

Enhancers cause a high level of transcription and activation of chromatin structure at target genes. Hyperacetylation of histones H3 and H4, a mark of active chromatin, is established broadly across target loci by enhancers that function over long distances. In the present study, we studied the role of an enhancer in methylation of various lysine residues on H3 by comparing a model gene locus having an active enhancer with one in which the enhancer has been inactivated within the context of minichromosomes. The intact enhancer affected histone methylation at K4, K9 and K36 in distinct ways depending on the methylation level and the location in the locus. All three lysine residues were highly tri‐methylated in the coding region of the gene linked to the active enhancer but not the inactive enhancer. However di‐methylation of K9 and K36 was not affected by the enhancer. The enhancer region itself was marked by mono‐methylation at K4 and K9, distinguishing it from the methyl marks in the gene coding region. These results indicate that an enhancer has roles in establishing active histone methylation patterns linked with gene transcription rather than removing methylation linked with gene inactivation.
Residues affecting the chloride regulation and substrate selectivity of the angiotensin‐converting enzymes (ACE and ACE2) identified by site‐directed mutagenesis
Authors: Rushworth Christopher A. , Guy Jodie L. , Turner Anthony J.
Published: November 2008

Angiotensin‐converting enzyme (ACE) and its homologue angiotensin‐converting enzyme 2 (ACE2) are critical counter‐regulatory enzymes of the renin–angiotensin system, and have been implicated in cardiac function, renal disease, diabetes, atherosclerosis and acute lung injury. Both ACE and ACE2 have catalytic activity that is chloride sensitive and is caused by the presence of the CL1 and CL2 chloride‐binding sites in ACE and the CL1 site in ACE2. The chloride regulation of activity is also substrate dependent. Site‐directed mutagenesis was employed to elucidate which of the CL1 and CL2 site residues are responsible for chloride sensitivity. The CL1 site residues Arg186, Trp279 and Arg489 of testicular ACE and the equivalent ACE2 residues Arg169, Trp271 and Lys481 were found to be critical to chloride sensitivity. Arg522 of testicular ACE was also confirmed to be vital to the chloride regulation mediated by the CL2 site. In addition, Arg514 of ACE2 was identified as a residue critical to substrate selectivity, with the R514Q mutant, relative to the wild‐type, possessing a fourfold greater selectivity for the formation of the vasodilator angiotensin‐(1–7) from the vasoconstrictor angiotensin II. The enhancement of angiotensin II cleavage by R514Q ACE2 was a result of a 2.5‐fold increase in Vmax compared with the wild‐type. Inhibition of ACE2 was also found to be chloride sensitive, as for testicular ACE, with residues Arg169 and Arg514 of ACE2 identified as influencing the potency of the ACE2‐specific inhibitor MLN‐4760. Consequently, important insights into the chloride sensitivity, substrate selectivity and inhibition of testicular ACE and ACE2 were elucidated.
Towards understanding the nitrogen signal transduction for nif gene expression in Klebsiella pneumoniae
Authors: Glöer Jens , Thummer Robert , Ullrich Heike , Schmitz Ruth A.
Published: November 2008

In the diazotroph Klebsiella pneumoniae, the nitrogen sensory protein GlnK mediates the cellular nitrogen status towards the NifL/NifA system that regulates transcription of the nitrogen fixation genes in response to ammonium and molecular oxygen. To identify amino acids of GlnK essential for this signal transduction by protein–protein interaction, we performed random point mutagenesis by PCR amplification under conditions of reduced Taq polymerase fidelity. Three thousand two hundred mutated glnK genes were screened to identify those that would no longer complement a K. pneumoniaeΔglnK strain for growth under nitrogen fixing conditions. Twenty‐four candidates resulting in a Nif− phenotype were identified, carrying 1–11 amino acid changes in GlnK. Based on these findings, as well as structural data, several single mutations were introduced into glnK by site‐directed mutagenesis, and the Nif phenotype and the respective effects on NifA‐mediated nif gene induction was monitored in K. pneumoniae using a chromosomal nifK′–′lacZ fusion. Single amino acid changes resulting in significant nif gene inhibition under nitrogen limiting conditions were located within the highly conserved T‐loop (A43G, A49T and N54D), the body of the protein (G87V and K79E) and in the C‐terminal region (I100M, R103S, E106Q and D108G). Complex formation analyses between GlnK (wild‐type or derivatives) and NifL or NifA in response to 2‐oxoglutarate indicated that: (a) besides the T‐loop, the C‐terminal region of GlnK is essential for the interaction with NifL and NifA and (b) GlnK binds both proteins in the absence of 2‐oxoglutarate, whereas, in the presence of 2‐oxoglutarate, NifA is released but NifL remains bound to GlnK.
Association of aplastic anaemia and Fanconi's disease with HLA‐DRB1 alleles
Authors: Yari F. , Sobhani M. , Vaziri M. Z. , Bagheri N. , Sabaghi F. , Talebian A.
Published: November 2008

One of the most fascinating areas of research within the field of histocompatibility at present time concerns an observation that a major human histocompatibility system, human leucocyte antigen (HLA), is deeply involved in the development of a great number of diseases. Major histocompatibility complex is the most polymorphic system in the genome of different species. Recognition of HLA alleles could be useful in transplantation and disease studies. Genetic construct of HLA DRB1 was studied in Iranian normal populations and patients with aplastic anaemia and Fanconi's disease. DNA was extracted from the whole blood of 466 normal, 35 aplastic anaemia and 10 Fanconi's individuals. Then DRB1 gene polymorphism was studied by polymerase chain reaction‐sequence‐specific primer method. The HLA DRB1 gene analysis showed increase of DRB1*07 in aplastic anaemia patients compared to normal population (P = 0.02). According to this study, the frequency of DRB1*07 in normal individuals was 8.3, and in aplastic anaemia patients, 15.7%. Additionally, the frequency of DRB1*04 in normal, aplastic anaemia and Fanconi's individuals was 10, 5.7 and 20%, respectively. Our results of investigation showed correlation between some HLA alleles with the studied diseases. We reported the frequency of various DR types in aplastic and Fanconi's patients. This study could imply the possible role of HLA‐DRB1*07 in the incidence of aplastic anaemia. Moreover, the frequency of DRB1*04, DRB1*03 and DRB1*15 alleles showed intermediate correlation with Fanconi's anaemia.
Galactic dynamo action in presence of stochastic α and shear
Authors: Sur Sharanya , Subramanian Kandaswamy
Published: November 2008

Using a one-dimensional αω-dynamo model appropriate to galaxies, we study the possibility of dynamo action driven by a stochastic α-effect and shear. To determine the field evolution, one needs to examine a large number of different realizations of the stochastic component of α. The net growth or decay of the field depends not only on the dynamo parameters but also on the particular realization, the correlation time of the stochastic α compared to turbulent diffusion time-scale and the time over which the system is evolved. For dynamos where both a coherent and fluctuating α are present, the stochasticity of α can help alleviate catastrophic dynamo quenching, even in the absence of helicity fluxes. One can obtain final field strengths up to a fraction ∼0.01 of the equipartition field Beq for dynamo numbers |D| ∼ 40, while fields comparable to Beq require much larger degree of α-fluctuations or shear. This type of dynamo may be particularly useful for amplifying fields in the central regions of disc galaxies.
Inverse Modeling Approach to Allogenic Karst System Characterization
Authors: Dörfliger N. , Fleury P. , Ladouche B.
Published: November 2008

Allogenic karst systems function in a particular way that is influenced by the type of water infiltrating through river water losses, by karstification processes, and by water quality. Management of this system requires a good knowledge of its structure and functioning, for which a new methodology based on an inverse modeling approach appears to be well suited. This approach requires both spring and river inflow discharge measurements and a continuous record of chemical parameters in the river and at the spring. The inverse model calculates unit hydrographs and the impulse responses of fluxes from rainfall hydraulic head at the spring or rainfall flux data, the purpose of which is hydrograph separation. Hydrograph reconstruction is done using rainfall and river inflow data as model input and enables definition at each time step of the ratio of each component. Using chemical data, representing event and pre‐event water, as input, it is possible to determine the origin of spring water (either fast flow through the epikarstic zone or slow flow through the saturated zone). This study made it possible to improve a conceptual model of allogenic karst system functioning. The methodology is used to study the Bas‐Agly and the Cent Font karst systems, two allogenic karst systems in Southern France.
Another Aboriginal death in custody: uneasy alliances and tensions in the Mulrunji case
Authors: Corrin Jennifer , Douglas Heather
Published: November 2008

The death of an Aboriginal man, Mulrunji, in an Australian police cell in 2004 precipitated an extraordinary response from the community. The usual distinctions between the roles of police, coroner, prosecutors and politicians became confused and merged in the media maelstrom that followed the death. Uneasy alliances developed which qualified the binary response of right versus wrong. Could the coroner's findings be reconciled with the decision of the prosecutor not to try the police officer involved? Was the government's response of overriding the decision of the independent prosecutor justified? What does this case tell us about the adversarial and inquisitorial approaches to evidence? This paper examines the tensions at play in the response to the death of Mulrunji and explores the wide reaching implications for law and justice in death in custody cases.
Support networks of older people living in the community
Authors: Drennan Jonathan , Treacy Margaret P. , Butler Michelle , Byrne Anne , Fealy Gerard , Frazer Kate , Irving Kate
Published: November 2008

Aim.  The aim of the study was to identify the social support networks of older people living in the community in Ireland using Wenger’s (1994) network typology.

Background.  The population of older people in the community is increasing. With increasing age and changes in family circumstances a substantial proportion of older people will require social, psychological and instrumental support. However a lack of adequate social support networks for vulnerable older people can result in poor health, loneliness and isolation.

Method.  A national, cross‐sectional telephone survey of 683 people aged between 65 and 99 years was undertaken using the Practitioner Assessment of Network Type as the basis for identifying social support networks.

Results.  The results demonstrated that the majority of older people were living in stable and supportive social networks and reported high levels of contact with family, friends and neighbours. However, a significant minority of older people were living in vulnerable networks. Older people in these networks are susceptible to loneliness, isolation and poor emotional and physical health.

Conclusion.  Through the identification of people in vulnerable networks, nurses working both in the hospital and community setting can ensure that formal support is aimed at providing care to older people who do not have access to informal care networks. Furthermore, the predictive utility of the Practitioner Assessment Network Type (PANT) can enable nurses to identify people at risk of poor social support.
Sampling Procedures for Coordinating Stratified Samples: Methods Based on Microstrata
Authors: Nedyalkova Desislava , Pea Johan , Tillé Yves
Published: November 2008

The aim of sampling coordination is to maximize or minimize the overlap between several samples drawn successively in a population that changes over time. Therefore, the selection of a new sample will depend on the samples previously drawn. In order to obtain a larger (or smaller) overlap of the samples than the one obtained by independent selection of samples, a dependence between the samples must be introduced. This dependence will emphasize (or limit) the number of common units in the selected samples. Several methods for coordinating stratified samples, such as the Kish & Scott method, the Cotton & Hesse method, and the Rivière method, have already been developed. Using simulations, we compare the optimality of these methods and their quality of coordination. We present six new methods based on permanent random numbers (PRNs) and microstrata. These new methods have the advantage of allowing us to choose between positive or negative coordination with each of the previous samples. Simulations are run to test the validity of each of them.
Tetranucleotide microsatellite loci from the black bear (Ursus americanus)
Authors: SANDERLIN JAMIE SKVARLA , FAIRCLOTH BRANT C. , SHAMBLIN BRIAN , CONROY MICHAEL J.
Published: November 2008

We describe primers and polymerase chain reaction conditions to amplify 21 tetranucleotide microsatellite DNA loci in black bears (Ursus americanus). We tested primers using individuals from two populations, one each in Georgia and Florida. Among individuals from Georgia (n = 29), primer pairs yielded an average of 2.9 alleles (range, one to four) and an average observed heterozygosity (HO) of 0.50 (range, 0.00 to 0.79). Among individuals from Florida (n = 19), primer pairs yielded an average of 5.7 alleles (range, one to 14) and an HO of 0.55 (range, 0.00 to 1.00). A comparison of previously developed markers with individuals from Georgia suggests that bear populations in Georgia and Florida have reduced allelic diversity relative to other populations.