bluuebunny/crossref_metadata_2025 huggingface dataset:
Fish and mucus‐dwelling bacteria interact to produce a kairomone that induces diel vertical migration in Daphnia
Authors: BEKLIOGLU MERYEM , TELLI MURAT , GOZEN AYSE G.
Published: October 2006

1. Bacterial populations associated with fish have previously been documented to be crucial for the production of chemical signals governing the interactions between predator fish and zooplankton prey.

2. In this study, we investigated the roles of fish and mucus‐dwelling bacteria in kairomone production by conducting two sets of experiments related to elimination of bacteria with antibiotics and using fish mucus in bioassays of Daphnia pulex’s diel vertical migration.

3. Daphnia’s migratory response to the antibiotic‐treated fish was about half the strength of the response to the fish cue treatment. Furthermore, when the same antibiotic‐treated fish were removed from the antibiotic‐containing water and transferred into control water for 24 and 48 h, the extent of D. pulex’s migration depended on the length of the incubation period, apparently corresponding to the regeneration of bacterial colonies associated with mucus. The migration pattern observed in the 24 h treatment was similar to that of antibiotic‐treated fish. On the other hand, a pronounced migration occurred in the 48 h following antibiotic treatment; here, we found a higher density of fish surface dwelling bacteria than at the start of the experiment.

4. In the experiment involving fish mucus, the mucus‐enriched control water induced a weak response similar to antibiotic‐treated fish.

5. On the basis of the results from the two experiments, we suggest that both fish and fish mucus‐dwelling bacteria interact in the release of kairomone in ecologically relevant quantities.
Does excess carbon affect respiration of the rotifer Brachionus calyciflorus Pallas?
Authors: JENSEN THOMAS C. , ANDERSON THOMAS R. , DAUFRESNE MARTIN , HESSEN DAG O.
Published: October 2006

1. Herbivorous zooplankton maintain a rather constant elemental composition in their body mass as compared with the variability commonly encountered in their food. Furthermore, their high phosphorus (P) and nitrogen (N) content means that they often face an excess of carbon (C) in their diet. Regulation of this surplus of energy may occur via modulation of assimilation efficiency, or postassimilation by increased respiration (CO2) and/or excretion dissolved organic carbon, DOC. Whereas several studies have examined the effect of elemental imbalance in the genus Daphnia, few have examined other zooplankton taxa.

2. We investigated whether the rotifer Brachionus calyciflorus uses increased respiration as a means of stoichiometrically regulating excess dietary C. Growth rate and respiration were measured under different food qualities (C : N and C : P ratios).

3. Both C : N and C : P ratios in food had strong effects on growth rate, demonstrating strong nutrient limitation of rotifer growth when nutrient elements were depleted in the diet and indicating the need for stoichiometric regulation of excess ingested C.

4. Respiration measurements, supported by a stoichiometric model, indicated that excess C was not released as CO2 in B. calyciflorus and that nutrient balance must therefore be maintained by other means such as excretion of DOC or egestion in faecal material.
Large‐scale spatial and temporal dynamics of the vulnerable and highly mobile superb parrot
Authors: Manning Adrian D. , Lindenmayer David B. , Barry Simon C. , Nix Henry A.
Published: October 2006

Aim  To investigate the spatial and temporal dynamics of the vulnerable and highly mobile superb parrot (Polytelis swainsonii) across its range in south‐eastern mainland Australia.

Location  South‐eastern Australia (27°–37° S latitude and 141°–151° E longitude).

Methods  We used generalized additive models (GAMs) to model time‐specific bird atlas occurrence data against time‐specific plant productivity data, plus a range of environmental predictor variables. We then examined the effects of environmental variables on the temporal and spatial patterns of predicted abundance and distribution of the superb parrot using a correlative mapping approach.

Results  Key findings from GAM analysis were: (1) there was a strong positive relationship between abundance and plant productivity in all regions, but (2) the response of abundance to other predictor variables often differed between regions. Correlative mapping predictions of the abundance and distribution of the superb parrot also indicated that: (1) predicted abundance varied through time and space, (2) predicted abundance sometimes decreased in all regions, but at other times some regions had high abundance when others had low, and (3) changes in plant productivity (and therefore climate) were associated with this variation.

Main conclusion  The superb parrot favours productive landscapes that are also favoured for agriculture. Movements appear to be associated with seasonal and year to year climate variability. Thus, variation in the recorded abundance of the superb parrot may mask population trends, suggesting that existing population estimates are unreliable. Also, high abundances in some areas, and at some times, may reflect deteriorating habitat conditions elsewhere rather than species recovery. Temporal variability in the distribution of the superb parrot makes it difficult to identify specific drought refugia. Consequently, through time, as key habitat continues to deteriorate, the species will become increasingly vulnerable and threatened. Whole‐landscape habitat conservation and restoration strategies are therefore needed to sustain superb parrot populations in the long‐term.
Spatial patterns and vegetation–site relationships of the presettlement forests in western New York, USA
Authors: Wang Yi‐Chen
Published: October 2006

Aim  The purposes of this study were to develop a Geographic Information System and spatial analytical methodology to reconstruct and represent the presettlement vegetation in a spatially continuous manner over large areas and to investigate vegetation–site relationships before widespread changes of the vegetation had taken place.

Location  The study area was the Holland Land Company Purchase in western New York, a 14,400 km2 area extending across the physiographic provinces of the Erie–Ontario Lowlands and the Appalachian Uplands.

Methods  Bearing‐tree records from the Holland Land Company township surveys of western New York in c. 1800 were collected and analysed. The geostatistical method of indicator kriging was used to map spatially continuous representations of individual tree species. Rule‐based and statistically clustered approaches were used to analyse and classify the reconstructed tree species distributions in order to obtain the vegetation association distribution. Contingency table analysis was conducted to quantify species relationships with soil conditions.

Results  The presettlement vegetation at both the tree species and the vegetation association levels were easier to interpret and visually more effective as a spatially continuous representation than as a discontinuous distribution of symbols. The results for tree species were probability occurrences of species distribution, showing spatial patterns that were not apparent in discrete maps of points or in summary tables of species frequencies. Analysis of the 8792 bearing trees suggested the dominance of American beech (Fagus grandifolia) and sugar maple (Acer saccharum) in the forest composition 200 years ago. Both soil drainage and texture were important site determinants of the vegetation in western New York. The rule‐based and statistically clustered approaches had the advantage of summarizing vegetation compositional patterns in a single image, thus avoiding the need to delineate manually and subjectively the location of boundaries between adjacent vegetation associations.

Main conclusions  The study offers more insights into the spatial pattern of presettlement forests in western New York than do prior studies. The spatially continuous representation could also enable the comparison of vegetation distribution from data sources that have different sampling schemes, for example the comparison of presettlement vegetation from the presettlement land survey records with current vegetation from modern forest inventories. The results are of value, providing a useful benchmark against which to examine vegetation change and the impacts of human land use.
The impact of quorum sensing and swarming motility on Pseudomonas aeruginosa biofilm formation is nutritionally conditional
Authors: Shrout Joshua D. , Chopp David L. , Just Collin L. , Hentzer Morten , Givskov Michael , Parsek Matthew R.
Published: October 2006

The role of quorum sensing in Pseudomonas aeruginosa biofilm formation is unclear. Some researchers have shown that quorum sensing is important for biofilm development, while others have indicated it has little or no role. In this study, the contribution of quorum sensing to biofilm development was found to depend upon the nutritional environment. Depending upon the carbon source, quorum‐sensing mutant strains (lasIrhlI and lasRrhlR) either exhibited a pronounced defect early in biofilm formation or formed biofilms identical to the wild‐type strain. Quorum sensing was then shown to exert its nutritionally conditional control of biofilm development through regulation of swarming motility. Examination of pilA and fliM mutant strains further supported the role of swarming motility in biofilm formation. These data led to a model proposing that the prevailing nutritional conditions dictate the contributions of quorum sensing and swarming motility at a key juncture early in biofilm development.
Concerted action of plasmid maintenance functions: partition complexes create a requirement for dimer resolution
Authors: Bouet Jean‐Yves , Bouvier Marie , Lane David
Published: October 2006

Partition of prokaryotic DNA requires formation of specific protein–centromere complexes, but an excess of the protein can disrupt segregation. The mechanisms underlying this destabilization are unknown. We have found that destabilization by the F plasmid partition protein, SopB, of plasmids carrying the F centromere, sopC, results from the capacity of the SopB–sopC partition complex to stimulate plasmid multimerization. Mutant SopBs unable to destabilize failed to increase multimerization. Stability of wild‐type mini‐F, whose ResD/rfsF site‐specific recombination system enables it to resolve multimers to monomers, was barely affected by excess SopB. Destabilization of plasmids lacking the rfsF site was suppressed by recF, recO and recR, but not by recB, mutant alleles, indicating that multimerization is initiated from single‐strand gaps. SopB did not alter the amounts or distribution of replication intermediates, implying that SopB–DNA complexes do not create single‐strand gaps by blocking replication forks. Rather, the results are consistent with SopB–DNA complexes channelling gapped molecules into the RecFOR recombination pathway. We suggest that extended SopB–DNA complexes increase the likelihood of recombination between sibling plasmids by keeping them in close contact prior to SopA‐mediated segregation. These results cast plasmid site‐specific resolution in a new role – compensation for untoward consequences of partition complex formation.
Global transcriptional upregulation in the absence of increased translation in Chlamydia during IFNγ‐mediated host cell tryptophan starvation
Authors: Ouellette Scot P. , Hatch Thomas P. , AbdelRahman Yasser M. , Rose Lorne A. , Belland Robert J. , Byrne Gerald I.
Published: October 2006

The developmentally regulated intracellular pathogen Chlamydia pneumoniae is a natural tryptophan auxotroph. These organisms survive tryptophan starvation induced by host cell activation with IFNγ by blocking maturation to the infectious form. In most bacteria, the stringent response is induced during amino acid starvation to promote survival. However, the response of obligate intracellular pathogens, which are predicted to lack stringent responses to amino acid starvation, is poorly characterized. Chlamydial transcription and translation were analysed during IFNγ‐mediated tryptophan starvation using genomic normalization methods, and the data revealed the novel findings that: (i) global chlamydial transcription was upregulated; and (ii) protein synthesis was dramatically reduced. These results indicate a dysregulation of developmental gene expression and an uncoupling of transcription from translation. These observations represent an alternative survival strategy for host‐adapted obligate intracellular bacterial pathogens that have lost the genes for stringent control during reductive evolution.
Netherton syndrome: Successful use of topical tacrolimus and pimecrolimus in four siblings
Authors: Saif Ghada Bin , Al‐Khenaizan Sultan
Published: October 2006

Netherton's syndrome (NS) is a rare autosomal recessive disease comprised of ichthyosis in the form of ichthyosis linearis circumflexa, hair shaft defects and atopic manifestations with an elevated IgE level. Various therapeutic options have been used in NS with variable success. Tacrolimus and pimecrolimus belong to the family of calcineurin inhibitors. They bind cytoplasmic proteins and the resulting complex binds calcineurin, inhibiting its ability to dephosphorylate the nuclear factor of activated T cells, thus suppressing gene transcription. There have been conflicting reports of the usefulness of tacrolimus in NS patients, with systemic absorption being the main adverse outcome. Here we report four Saudi siblings (two boys and two girls) with NS who were treated with topical tacrolimus and pimecrolimus with good control of their skin disease without any toxic effect. To our knowledge, this is the second report of the use of topical pimecrolimus in NS in the English literature.
99mTc‐MIBI imaging of cutaneous AIDS‐associated Kaposi's sarcoma
Authors: Peer Fawzia I. , Pui Margaret H. , Mosam Anisa , Rae William I. D.
Published: October 2006

Background  Kapoksi's sarcoma (KS) is a common neoplasm complicating acquired immunodeficiency syndrome (AIDS). Skin, mucus membranes, lymph nodes, gastrointestinal tract and lungs may be involved. Kaposi's sarcoma has been demonstrated by scintigraphy, and a 99mTc‐hexakis‐2‐methoxy isobutyl isonitrile (MIBI) scan can demonstrate lymphoma and tumors of the brain, nasopharynx, thyroid, parathyroid, lung, breast and kidney. It may also be useful for detecting and delineating the extent of KS. The objective of this study was to determine the efficacy of 99mTc‐MIBI scanning to demonstrate cutaneous AIDS‐associated KS, lymphedema and lymphadenopathy in the extremities.

Methods  Whole body 99mTc‐MIBI scans were obtained on 40 patients with AIDS‐associated KS. Abnormal uptake of 99mTc‐MIBI in the skin, subcutaneous soft tissues and lymph nodes was compared with the clinical assessment.

Results  The 99mTc‐MIBI uptake was noted in the cutaneous/subcutaneous KS of the extremities with a sensitivity of 73.53%, a specificity of 96.91% and an accuracy of 91.31%. Abnormal lymph nodes and lymphedema were detected in more patients on 99mTc‐MIBI scans (33 and 18 patients) than clinical assessment (10 and 12 patients), respectively. Lymphedema of the lower extremity was found in four of 17 patients without any palpable or abnormal lymph node uptake of 99mTc‐MIBI in the inguinal regions. Follow‐up 99mTc‐MIBI scans after treatment showed no uptake in the skin lesions and decreased uptake in the lymph nodes corresponding to complete clearing on clinical assessment.

Conclusions  99mTc‐MIBI imaging provides additional information on the extent of lymph node involvement and more precise staging and therapeutic planning. It may be useful as a predictive test or follow up of response of cutaneous KS to treatment.
Cutaneous leishmaniasis reactivation 2 years after treatment caused by systemic corticosteroids – first report
Authors: Tuon Felipe Francisco , Sabbaga Amato Valdir , Floeter‐Winter Lucile Maria , De Andrade Zampieri Ricardo , Amato Neto Vicente , Siqueira França Francisco Oscar , Shikanai‐Yasuda Maria Aparecida
Published: October 2006

American tegumentary leishmaniasis (ATL), an endemic anthropozoonosis in various countries in the world, is caused by parasites of the genus Leishmania. Despite reports on ATL reactivation as a result of immunosuppression, to the best of our knowledge, this paper describes the first case of ATL reactivation in its localized form (cutaneous leishmaniasis) associated with the administration of systemic corticosteroids. The possible action of corticosteroids on the host immune response to the parasite in patients with localized cutaneous leishmaniasis is discussed. This report demonstrates the possibility of ATL reactivation in patients using corticosteroids, an observation that should be considered in individuals treated with this medication.
Metastatic esophageal carcinoma masquerading as inflammatory breast carcinoma
Authors: Nebesio Christy L. , Goulet Robert J. , Helft Paul R. , Billings Steven D.
Published: October 2006

A 50‐year‐old Caucasian woman with a history of esophageal adenocarcinoma presented with a 3‐week history of right breast swelling and progressive erythema. Twenty‐two months prior to presentation, she had been diagnosed with adenocarcinoma of the esophagus (T3,N1,M1a) and underwent neoadjuvant chemoradiotherapy followed by surgical resection.

On physical examination, the right breast was red, swollen (40% larger than the contralateral breast), tender to palpation, and warm to the touch (Fig. 1). No mass was palpable. On the basis of the clinical findings, inflammatory breast carcinoma was suspected. A punch biopsy revealed a poorly differentiated adenocarcinoma with extensive involvement of dermal lymphatics (Fig. 2). The clinical and histologic differential diagnosis included inflammatory breast carcinoma vs. metastatic esophageal adenocarcinoma to the skin of the breast.

The affected breast resembled inflammatory breast carcinoma with erythema and prominent edema. The edema resulted in partial inversion of the nipple

image

Within the reticular dermis and dermal lymphatics, there was a poorly differentiated adenocarcinoma. Many of the tumor cells had a signet ring morphology (hematoxylin and eosin, ×200)

image

To resolve this question, immunohistochemical stains for estrogen and progesterone receptors and CDX‐2 (BioGenex, San Ramon, CA, USA) were performed. CDX‐2 is an intestinal homeobox gene expressed in gastrointestinal epithelium and gastrointestinal tumors. The tumor nuclei were positive for CDX‐2 but negative for both steroid receptors (Fig. 3), confirming the diagnosis of metastatic esophageal adenocarcinoma.

The tumor cells had strong nuclear immunoreactivity for CDX‐2 (CDX‐2 immunohistochemical stain, ×400)

image
The role of cyclic‐AMP on arginase activity by a murine macrophage cell line (RAW264.7) stimulated with lipopolysaccharide from Actinobacillus actinomycetemcomitans
Authors: Sosroseno W. , Musa M. , Ravichandran M. , Fikri Ibrahim M. , Bird P. S. , Seymour G. J.
Published: October 2006

Aims:  The aim of the present study was to determine the role of cyclic adenosine monophosphate (cAMP) on arginase activity in a murine macrophage cell line (RAW264.7 cells) stimulated with lipopolysaccharide (LPS) from Actinobacillus actinomycetemcomitans.

Materials and methods:  The cells were treated with A. actinomycetemcomitans LPS for 24 h. The effects of SQ22536 (an adenylyl cyclase inhibitor), ODQ (a guanylyl cyclase inhibitor), dibutyryl cAMP (a cAMP analog), 8‐bromo cyclic guanosine monophosphate (a cGMP analog), forskolin (an adenylyl cylase activator), and cycloheximide (a protein synthesis inhibitor) on arginase activity in A. actinomycetemcomitans LPS‐stimulated RAW264.7 cells were also determined. Arginase activity was assessed in LPS‐stimulated cells in the presence of 3‐isobutyl‐1‐methylxanthine (IBMX), siguazodan and rolipram [phosphodiesterase (PDE) inhibitors] as well as KT5720 [a protein kinase A (PKA) inhibitor].

Results:  Arginase activity in A. actinomycetemcomitans LPS‐stimulated RAW264.7 cells was suppressed by SQ22536 but not ODQ. Enhancement of arginase activity was observed in the presence of cAMP analog or forskolin but not cGMP analog. Cycloheximide blocked arginase activity in the cells in the presence of cAMP analog or forskolin with or without A. actinomycetemcomitans LPS. IBMX augmented arginase activity in A. actinomycetemcomitans LPS‐stimulated cells. Rolipram (a PDE4 inhibitor) increased the levels of arginase activity higher than siguazodan (a PDE3 inhibitor) in the antigen‐stimulated cells. The effect of cAMP analog or forskolin on arginase activity in the presence or absence of A. actinomycetemcomitans LPS was blocked by the PKA inhibitor (KT5720).

Conclusion:  The results of the present study suggest that A. actinomycetemcomitans LPS may stimulate arginase activity in murine macrophages (RAW264.7 cells) in a cAMP‐PKA‐dependent pathway.
Analysis of the strain relatedness of oral Candida albicans in patients with diabetes mellitus using polymerase chain reaction‐fingerprinting
Authors: Manfredi M. , McCullough M. J. , Al‐Karaawi Z. M. , Vescovi P. , Porter S. R.
Published: October 2006

To increase our understanding of Candida pathogenicity, the identification of those strains most frequently associated with infections is of paramount importance. Polymerase chain reaction (PCR)‐based methods are extremely effective in differentiating and determining reproducibility, they require minimum starting material and are rapid and simple to perform. In this study, the genetic relatedness of Candida albicans was assessed for two geographically different patient groups (London, UK and Parma, Italy) affected by diabetes mellitus. C. albicans samples from the oral cavities of non‐diabetic healthy subjects were also examined by PCR fingerprinting to evaluate the possible genetic differences among endogenous strains in individuals with and without diabetes mellitus. PCR fingerprinting, with subsequent phylogenetic analysis of C. albicans isolates from the diabetic patients from London and Italy and from the non‐diabetic subjects, revealed that there were significant differences (P < 0.0001) between C. albicans isolates indicative of the distinct ecological niches that occur in the oral cavities of these patient cohorts. The most diverse group comprised the isolates from the diabetic patients in the UK, possibly reflecting the antifungal treatment that these patients had received. Further studies that include isolates from patient cohorts with systemic diseases other than diabetes mellitus, and from more diverse geographic localities are required to explain the relatedness of C. albicans isolates in the mouth.
The effects of tetracycline, minocycline, doxycycline and ofloxacin on Prevotella intermedia biofilm
Authors: Takahashi N. , Ishihara K. , Kimizuka R. , Okuda K. , Kato T.
Published: October 2006

Prevotella intermedia, a black‐pigmented, anaerobic, gram‐negative bacterium, is associated with various type of periodontitis. Antibiotic treatments via a systemic or local route have been reported as being useful for treating periodontal disease. The purpose of this study was to examine the effects of four antibiotics, tetracycline (TET), minocycline (MINO), doxycycline (DOXY) and ofloxacin (OFLX) on P. intermedia biofilms at minimum inhibitory concentrations (MIC) from one‐fold to 100‐fold. MICs were determined for planktonic cells. Biofilm formation was determined with the crystal violet stain method and the bioactivities in the biofilms were determined with the adenosine triphosphate (ATP) ‐bioluminescent assay using a 96‐well culture plate. At one‐fold MIC, DOXY inhibited biofilm formation by P. intermedia ATCC 25611. Other antibiotics at one‐fold MIC had no effects on the biofilm formation of tested bacterial strains. In P. intermedia ATCC 25611 biofilms, all the antibiotics tested showed inhibitory activities at five‐ to 100‐fold MICs. In the biofilms of P. intermedia strains, except ATCC 25611, treated with three tetracycline antibiotics, the bioactivities were significantly increased, indicating the difficulties involved in designing antibiotic therapy for periodontal disease.
Identification of genetic differences between two clinical isolates of Streptococcus mutans by suppression subtractive hybridization
Authors: Guo L. H. , Shi J. N. , Zhang Y. , Liu X. D. , Duan J. , Wei S.
Published: October 2006

Streptococcus mutans is generally considered to be the principal aetiological agent for dental caries. Phenotypic variation in strains is often associated with differences in gene content, so the isolation of DNA fragments from these genes or associated regions is illuminating. The S. mutans strains 9‐1 and 9‐2, which both colonized the same oral cavity, were selected after screening for the possession of suspected virulence traits. Genomic DNA of strain 9‐1 was used as the tester, and that of 9‐2 was used as the driver. Suppression subtractive hybridization (SSH) was applied between the tester and the driver DNAs. The subtractive products were cloned into a pCR2.1 vector. Clone libraries representing sequence differences were obtained. The subtractive fragments that were found specifically in strain 9‐1 but not in strain 9‐2 were identified by dot blotting and then sequenced. BLASTn and BLASTx sequence homology analyses were subsequently performed. Twenty‐seven sequences were found in the genome of strain 9‐1 that were not in 9‐2. Among them, three revealed no homology to published nucleotide sequences while the remaining sequences showed 81–100% homology to known genes of S. mutans strain UA159. These sequences are involved in competence development, signal transduction and transcriptional regulation, repairing stress damage, transport, carbohydrate catabolism, biochemical synthesis, or unknown functions. Differences exist in the genomes of different S. mutans isolates. SSH is effective in screening for S. mutans strain specific DNA sequences.
The role of CD4+ and CD8+ T cells on antibody production by murine Peyer's patch cells following mucosal presentation of Actinomyces viscosus
Authors: Sosroseno W. , Bird P. S. , Gemmell E. , Seymour G. J.
Published: October 2006

The aim of this study was to determine the role of CD4 and CD8 cells on specific antibody production by murine Peyer's patch (PP) cells after oral immunization with Actinomyces viscosus in mice. Female DBA/2 mice were orally immunized with three low doses of heat‐killed A. viscosus. Sham‐immunized mice served as a control group. Mice were depleted of CD4 or CD8 cells by intraperitoneal injection of anti‐CD4 or anti‐CD8 antibodies daily for 3 days before oral immunization. One week after the last oral immunization, PPs were removed and cell suspensions were cultured with A. viscosus. Specific antibody production in the culture supernatants was assessed by enzyme‐linked immunosorbent assay. The results showed that oral immunization with A. viscosus induced a predominant specific immunoglobulin A (IgA) response by PP cells and, to a lesser extent, IgM antibodies. Depletion of CD4 but not CD8 cells suppressed the production of specific antibodies. These results suggest that oral immunization with low doses of A. viscosus may induce the production of specific antibodies by murine PP cells in a CD4‐cell‐dependent fashion.
Serotype‐specific polysaccharide of Streptococcus mutans contributes to infectivity in endocarditis
Authors: Nagata E. , Okayama H. , Ito H.‐O. , Yamashita Y. , Inoue M. , Oho T.
Published: October 2006

Streptococcus mutans and other viridans streptococci have been implicated as major etiological agents of infective endocarditis. The serotype‐specific rhamnose‐glucose polysaccharide (RGP) of S. mutans has several biological functions that appear to be essential for the induction of infective endocarditis. The aim of this study was to examine the contribution of RGP to the infectivity of S. mutans in infective endocarditis using a rat model. The RGP‐defective mutant of S. mutans showed reduced ability to induce infective endocarditis compared to the parental strain. The ability of S. mutans to induce infective endocarditis was not consistent with the binding capacity of the organism to extracellular matrix proteins. The results suggest that S. mutans containing whole RGP is more virulent than the RGP‐defective mutant, and the RGP has an important role for the induction of infective endocarditis by S. mutans.
Childhood allergic disorders in Samsun, Turkey: discrepancy between reported and diagnosed
Authors: Anlar F. Y. , Sancak Recep , Öztürk Fadil
Published: October 2006

Schoolchildren (n = 1310) randomly selected from 32 schools in Samsun, Northern Turkey, were screened using the International Study of Asthma and Allergies in Childhood questionnaire. The prevalence of wheezing and current (last 12 months) wheezing were 21% and 14%, respectively: 2.3% of this group had received the diagnosis of asthma by a physician. Allergic skin rash was described in 17.3% and rhinitis in 44.7%, while 2.6% had been diagnosed with eczema and 10.5%, with allergic rhinitis. Respiratory symptoms were more common among 6–7‐yr‐old children compared with those aged 13–14 yr, and tended to be more prevalent in urban and coastal regions. The discrepancy between the rate of allergic symptoms and diagnosed allergic disorders may indicate a need for increased public and professional awareness and screening for allergic disorders in this area.
Xenotransplantation – ethics and regulation
Authors: Ellison Tracy
Published: October 2006

Abstract:  Healthcare workers, researchers, and policy makers find themselves in challenging times, being required to make (often prompt) decisions in the face of novel ethical dilemmas. Moral theory may assist with decision‐making in complex areas of medicine such as the xenotransplantation of insulin‐producing cells to reverse diabetes. Moral theory attempts to capture intuitions about whether an action is right or wrong and it may gives us a deeper understanding of moral claims as it gives us an account as to why an action is good or bad. We may opt to choose different ethical frameworks such as consequentialism, principlism or a duty‐based approach, to assist with deciding a certain action in a particular scenario. The xenotransplantation of porcine insulin‐producing cells is a potential solution to the shortage of human tissue. It is crucial for the advancement of xenotransplantation that the benefits to society outweigh the risks and whilst there is enormous potential to assist mankind, there are unique bioethical challenges and dilemmas.

New treatment strategies should be regulated appropriately to minimize risks to patients, their relatives and the wider community. There are specific regulations (such as those developed by the FDA) that provide a robust framework for the safe implementation of xenotransplantation and more generally applicable ones such as the Declaration of Helsinki. Xenotransplantation is either morally acceptable or not to an individual. Patients must ultimately decide as to whether they would accept a certain form of treatment or not, a decision which would take into account their religious beliefs and categorical objections. There is no point in developing a treatment option unless there is good patient support. To that end, a study was conducted to ascertain the acceptance of tissue from different animal sources, by diabetic patients in England and Australia. Interviews were conducted to ensure that patients’ views were reflected in their answers. There were 316 English and 195 Australian questionnaire respondents and the vast majority would accept human (85%, 94%), porcine (68%, 85%) or non‐human primate (67%, 82%) tissue, respectively. This study suggests that a large proportion of diabetic patients may accept a xenotransplantation product.
Prevalence of Genes Encoding Exfoliative Toxins among Staphylococcus hyicus Isolated in Russia and Germany
Authors: Kanbar T. , Voytenko A. V. , Alber J. , Lämmler C. , Weiss R. , Zschöck M. , Shilov I. A. , Dmitrenko O. A. , Gintsburg A. L.
Published: October 2006

In the present study, previously characterized Staphylococcus hyicus isolated in Russia (n = 23) and Germany (n = 17) were investigated for the prevalence of the exfoliative toxin encoding genes exhA, exhB, exhC and exhD by multiplex PCR resulting in the detection of exhD positive strains among the S. hyicus isolated from pigs with exudative epidermitis in Russia and the detection of exhC and exhD for one and two strains isolated from exudative epidermitis in Germany respectively. The toxin gene negative strains were generally isolated from apparently healthy pigs, from other animals and from specimens where the relation between the isolation of S. hyicus and the clinical symptoms remained unclear. Partial sequencing of the toxin genes of selected exhC and exhD positive strains and comparing the sequencing results with sequences of exhC and exhD reference strains revealed an almost complete identity. The results of the present study were in agreement with the findings of Andresen and Ahrens (J. Appl. Microbiol., 96, 2004, 1265) and Andresen (J. Vet. Rec., 157, 2005, 376) that the presented multiplex PCR could be used to investigate S. hyicus for toxinogenic potential and that there is an association between the presence of toxin genes in S. hyicus strains from exudative epidermitis. However, comparable with the S. hyicus strains isolated in Germany which were investigated previously by Andresen (J. Vet. Rec., 157, 2005, 376), exhD seems to predominate in S. hyicus strains from Russia.
Abundant distribution of TARP γ‐8 in synaptic and extrasynaptic surface of hippocampal neurons and its major role in AMPA receptor expression on spines and dendrites
Authors: Fukaya Masahiro , Tsujita Mika , Yamazaki Maya , Kushiya Etsuko , Abe Manabu , Akashi Kaori , Natsume Rie , Kano Masanobu , Kamiya Haruyuki , Watanabe Masahiko , Sakimura Kenji
Published: October 2006

Transmembrane α‐amino‐3‐hydroxyl‐5‐isoxazolepropionate (AMPA) receptor regulatory proteins (TARPs) play pivotal roles in AMPA receptor trafficking and gating. Here we examined cellular and subcellular distribution of TARP γ‐8 in the mouse brain. Immunoblot and immunofluorescence revealed the highest concentration of γ‐8 in the hippocampus. Immunogold electron microscopy demonstrated dense distribution of γ‐8 on the synaptic and extrasynaptic surface of hippocampal neurons with very low intracellular labeling. Of the neuronal surface, γ‐8 was distributed at the highest level on asymmetrical synapses of pyramidal cells and interneurons, whereas their symmetrical synapses selectively lacked immunogold labeling. Then, the role of γ‐8 in AMPA receptor expression was pursued in the hippocampus using mutant mice defective in theγ‐8gene. In the mutant cornu ammonis (CA)1 region, synaptic and extrasynaptic AMPA receptors on dendrites and spines were severely reduced to 35–37% of control levels, whereas reduction was mild for extrasynaptic receptors on somata (74%) and no significant decrease was seen for intracellular receptors within spines. In the mutant CA3 region, synaptic AMPA receptors were reduced mildly at asymmetrical synapses in the stratum radiatum (67% of control level), and showed no significant decrease at mossy fiber–CA3 synapses. Therefore, γ‐8 is abundantly distributed on hippocampal excitatory synapses and extrasynaptic membranes, and plays an important role in increasing the number of synaptic and extrasynaptic AMPA receptors on dendrites and spines, particularly, in the CA1 region. Variable degrees of reduction further suggest that other TARPs may also mediate this function at different potencies depending on hippocampal subregions, input sources and neuronal compartments.
Improved outcome of facial nerve repair in rats is associated with enhanced regenerative response of motoneurons and augmented neocortical plasticity
Authors: Peeva Gergana P. , Angelova Srebrina K. , Guntinas‐Lichius Orlando , Streppel Michael , Irintchev Andrey , Schütz Ulrich , Popratiloff Anastas , Savaskan Nicolai E. , Bräuer Anja U. , Alvanou Athanasia , Nitsch Robert , Angelov Doychin N.
Published: October 2006

Within a recent study on the vibrissae motor performance after facial nerve repair in strains of blind (SD/RCS) and sighted (SD) rats we found that, despite persisting myotopic disorganization in the facial nucleus, the blind animals fully restored vibrissal whisking. Here we searched for morphological substrates of better recovery in the regenerating motoneurons and in the cerebral motor cortex. Expression analyses of the neurite growth‐related proteins f‐actin, neuronal class III β‐tubulin and plasticity‐related gene‐1, and stereological estimates of growth cone densities revealed a more vigorous regenerative response in the proximal nerve stump of blind SD/RCS rats compared with SD animals at 5–7 days after buccal nerve transection. Using c‐Fos immunoreactivity as a marker for neuronal activation, we found that the volume of the cortex acutely responding to nerve transection (facial muscles reactive volume, FMRV) in both hemispheres of intact sighted rats was twofold smaller than that measured in blind animals. One month after transection and suture of the right facial nerve (FFA) we found a twofold increase in the FMRV in both rat strains compared with intact animals. The FMRV in SD/RCS animals, but not in SD rats, returned to the values in intact rats 2 months after FFA. Our findings suggest that enhanced plasticity in the CNS and an augmented regenerative response of the injured motoneurons contribute to better functional recovery in blind rats.
Novel Drosophila two‐pore domain K+ channels: rescue of channel function by heteromeric assembly
Authors: Döring Frank , Scholz Henrike , Kühnlein Ronald P. , Karschin Andreas , Wischmeyer Erhard
Published: October 2006

Ten genes with essential structural features of two‐pore domain potassium channels were identified in the genome of Drosophila melanogaster. Two Drosophila two‐pore domain potassium subunits displayed substantial amino acid similarity to human TWIK‐related acid‐sensitive K+ (TASK) channels (38–43%), whereas all others were less than 26% similar to any human homolog. The cDNAs of Drosophila TASK (dTASK)‐6 and dTASK‐7 channels were isolated from adult fruit flies. In Northern blots dTASK transcripts were found predominantly in the head fraction of adult flies and whole‐mount brain in situ hybridizations showed strongly overlapping expression patterns of both dTASK isoforms in the antennal lobes. When heterologously expressed in Drosophila Schneider 2 cells, dTASK‐6 gave rise to rapidly activating K+‐selective currents that steeply depended on external pH. Structural elements in the extracellular M1–P1 loop of dTASK‐6 were found to be involved in proton sensation. In contrast to mammalian TASK channels, the pH sensitivity was independent of extracellular histidines adjacent to the GYG selectivity filter (His98). As revealed by mutational analysis, functional expression of dTASK‐7 was prevented by two nonconserved amino acids (Ala92‐Met93) in the pore domain. When these two residues were replaced by conserved Thr92‐Thr93, typical K+‐selective leak currents were generated that were insensitive to changes in external pH. Nonfunctional wildtype dTASK‐7 channels appeared to form heteromeric assemblies with dTASK‐6. Following cotransfection of dTASK‐6 and wildtype dTASK‐7 (or when engineered as concatemers), K+ currents were observed that were smaller in amplitude, harbored slower activation kinetics and were considerably less inhibited by local anesthetics as compared with dTASK‐6. Thus, pore‐loop residues in dTASK‐7 changed functional and pharmacological properties in heteromeric dTASK channels.
Leptin induces cyclooxygenase‐2 via an interaction with interleukin‐1β in the rat brain
Authors: Inoue Wataru , Poole Stephan , Bristow Adrian F. , Luheshi Giamal N.
Published: October 2006

In addition to its central effects on appetite regulation, leptin has been implicated in immune function and inflammation. Previous data suggested that leptin acts as an inflammatory signal within the brain, as exogenously administered leptin induced fever, a typical brain‐regulated inflammatory response. The present study aimed to delineate the inflammatory actions and cellular targets of leptin in the brain by examining its effects on the expression of interleukin (IL)‐1β and cyclooxygenase (COX)‐2, two important inflammatory components of the fever response. Intracerebroventricular injection of leptin (5 µg/rat) induced IL‐1β and COX‐2 mRNA and protein in the hypothalamus between 1 and 3 h after treatment as determined by reverse transcription‐polymerase chain reaction and immunohistochemistry. Coinjection of IL‐1 receptor antagonist (100 µg/rat, intracerebroventricular) attenuated leptin‐induced COX‐2, whereas IL‐1 receptor antagonist had no effect on endogenous IL‐1β levels, suggesting that leptin induces COX‐2 via, at least partly, IL‐1β action. IL‐1β protein expression was induced in macrophages in the meningis and perivascular space after leptin treatment, whereas COX‐2 induction was observed in endothelial cells, indicating the roles for these non‐neuronal cells in mediating inflammatory actions of leptin. In addition, neutralization of endogenous circulating leptin with anti‐leptin antiserum attenuated intraperitoneal lipopolysaccharide (100 µg/kg)‐induced brain IL‐1β and COX‐2 upregulation, suggesting that leptin indeed acts as an inflammatory signal to the brain during systemic inflammation. These findings are in contrast to the effects of leptin on appetite regulation where it is believed to act primarily on neurons, thus presenting a distinct anatomical basis for the inflammatory and appetite regulatory actions of leptin in the brain.
Comparison of seizure phenotype and neurodegeneration induced by systemic kainic acid in inbred, outbred, and hybrid mouse strains
Authors: McLin Jessica Pilar , Steward Oswald
Published: October 2006

We assessed inbred, outbred and hybrid mouse strains for susceptibility to seizures and neurodegeneration induced by systemic administration of kainic acid (KA). Each strain showed a unique pattern of susceptibility to seizures as assessed by the dose necessary to induce continuous tonic clonic seizures, progression through six seizure levels, the number of mice that failed to satisfy seizure criteria, and seizure‐induced mortality. In general, the C57BL/6, ICR, FVB/N, and BALB/c strains were resistant to seizures while the C57BL/10, DBA/2 J, and F1 C57BL/6*CBA/J strains were vulnerable. Neuronal cell death was quantified in four subfields of the hippocampus: CA3, the hilus of the dentate gyrus, CA1, and the dentate granule cell layer. Neurodegeneration was also semiquantitatively assessed in other brain regions including the neocortex, striatum, thalamus, hypothalamus and amygdala. Although there was variability in the extent of cell death within strains, there were significant differences in the amount of hippocampal cell death between strains and also different patterns of neurodegeneration in affected brain areas. In general, the C57BL/6, C57BL/10, and F1 C57BL/6*CBA/J strains were resistant to neurodegeneration while the FVB/N, ICR and DBA/2 J strains were vulnerable. The BALB/c strain was unique in that neurodegeneration was confined to the hippocampus. Consistent with previous findings, the resistant neurodegeneration phenotype was dominant in an F1 cross of resistant and vulnerable inbred strains. Our results, using a large number of mouse strains, definitively demonstrate that a mouse strain's seizure phenotype is not related to its neurodegeneration phenotype.
Pattern motion selectivity in population responses of area 18
Authors: Schmidt Kerstin E. , Castelo‐Branco Miguel , Goebel Rainer , Payne Bertram R. , Lomber Stephen G. , Galuske Ralf A. W.
Published: October 2006

It is commonly believed that the complexity of visual stimuli represented by individual neurons increases towards higher cortical areas. However, even in early visual areas an individual neuron's response is influenced by stimuli presented outside its classical receptive field. Thus, it has been proven difficult to characterize the coding of complex stimuli at the level of single neurons. We therefore investigated population responses using optical imaging in cat area 18 to complex stimuli, plaids. Plaid stimuli are composed of two superimposed gratings moving in different directions. They may be perceived as either two separate surfaces or as a global pattern moving in intermediate direction to the components' direction of motion. We found that in addition to activity maps representing the individual components' motion, plaid stimuli produced activity distributions matching the predictions from a pattern‐motion model in central area 18. Thereby, relative component‐ and pattern‐like modulations followed the degree of psychophysical pattern bias in the stimulus. Thus, our results strongly indicate that area 18 exhibits a substantial response to pattern‐motion signals at the population level suggesting the presence of intrinsic or extrinsic mechanisms that allow for integration of motion responses from far outside the classical receptive field.
Altered processing of corollary discharge in thalamic lesion patients
Authors: Bellebaum Christian , Hoffmann Klaus‐Peter , Koch Benno , Schwarz Michael , Daum Irene
Published: October 2006

Accumulating evidence suggests that thalamic nuclei relay corollary discharge information of saccadic eye movements, enabling the visual system to update the representation of visual space. The present study aimed to explore the effect of thalamic lesions in humans on updating‐related cortical processing. Event‐related potentials were recorded while four patients with impairments in using corollary discharge information and 12 healthy control subjects performed a saccadic double‐step task. In the experimental condition, which required the use of corollary discharge information, control subjects showed a pronounced positivity over the parietal cortex starting about 150 ms after first saccade onset, reflecting the updating process. In the patients, parietal processing related to updating was altered. Three patients showed evidence of reduced updating event‐related potential effects, consistent with a unilateral deficit in using corollary discharge information. In two patients, the event‐related potential topography differed significantly from the topography pattern observed in controls. Thalamic damage affects updating‐related processing, presumably due to insufficient transfer of saccade‐related information to parietal areas. This study thus provides further evidence for thalamic involvement in relaying corollary discharge information related to saccadic eye movements. Our data suggest that integration of corollary discharge and motor information occurs directly before the second saccade in a double‐step task.
Subthalamic nucleus lesions increase impulsive action and decrease impulsive choice − mediation by enhanced incentive motivation?
Authors: Uslaner Jason M. , Robinson Terry E.
Published: October 2006

The subthalamic nucleus (STN) is traditionally thought of as part of a system involved in motor control but recent evidence suggests that it may also play a role in other psychological processes. Here we examined the effects of STN lesions on two measures of impulsivity and found that STN lesions increased ‘impulsive action’ (produced behavioral disinhibition), as measured by performance on a differential reinforcement of low rates of responding task, but decreased ‘impulsive choice’ (impulsive decision making), as measured by a delay discounting task. In addition, amphetamine and food restriction increased ‘impulsive action’ and decreased ‘impulsive choice’ to a greater extent in STN‐lesioned animals than in sham controls. We speculate that these apparently discrepant effects may be because STN lesions enhance the incentive salience assigned to rewards. These findings suggest that the STN may serve as a novel target for the treatment of psychological disorders characterized by deficits in behavioral control, such as drug addiction and attention deficit hyperactivity disorder.