A genetic switch controls Pseudomonas aeruginosa surface colonization

Efficient colonization of mucosal surfaces is essential for opportunistic pathogens like Pseudomonas aeruginosa, but how bacteria collectively and individually adapt to optimize adherence, virulence and dispersal is largely unclear. Here we identified a stochastic genetic switch, hecR-hecE, which is expressed bimodally and generates functionally distinct bacterial subpopulations to balance P. aeruginosa growth and dispersal on surfaces. HecE inhibits the phosphodiesterase BifA and stimulates the diguanylate cyclase WspR to increase c-di-GMP second messenger levels and promote surface colonization in a subpopulation of cells; low-level HecE-expressing cells disperse. The fraction of HecE+ cells is tuned by different stress factors and determines the balance between biofilm formation and long-range cell dispersal of surface-grown communities. We also demonstrate that the HecE pathway represents a druggable target to effectively counter P. aeruginosa surface colonization. Exposing such binary states opens up new ways to control mucosal infections by a major human pathogen.

Comparison of attitudes to media representation of mental illness between journalists and mental health professionals in Russia with German-speaking countries of Switzerland, Germany, and Austria

BACKGROUND

The media are an important source of information on mental health. They are often implicit in reinforcing negative stereotypes of people with mental health problems. There are no studies in German-speaking countries or Russia on media attitudes to mental health and mental health professionals' (MHP) attitudes to the media.

AIMS

This study explored journalists and MHPs attitudes to mental health media reporting in the German speaking countries of Switzerland, Germany, and Austria and in Russia.

METHODS

A cross-sectional online internet survey, of ten Likert scale statements to ascertain perceptions of stigma, role, and training needs following the STROBE guidance was conducted among journalists and MHPs via their professional organizations. A non-discriminatory exponential snowballing technique leading to non-probability sampling was used. Descriptive statistics, Kruskal-Wallis, and a post hoc Dunn's multiple comparisons test using Bonferroni adjustment were used to analyze data.

RESULTS

A total of 106 German-speaking and 78 Russian journalists, 109 German-speaking, and 82 Russian MHPs fully answered the survey. Journalists felt the media were more balanced about mental health than MHPs, and MHPs were wary of engagement with the media. Small minorities of journalists had engaged with mental health training, similarly few MHPs had engaged with media training, but both groups were interested in doing so in the future. Significant differences between German and Russian speaking respondents were found on a range of issues (e.g. stigmatization, image about psychotherapy, the media/MHPs, and their own role in engaging with the media/MHPs). Russians were more likely to know specialized (media/mental health awareness) training compared to German-speaking MHPs and journalists.

CONCLUSION

There are potential opportunities to engage journalists and MHPs in training about each other's worlds and reducing stigma toward mental illness through engaging MHPs with the media.

Stimulatory MAIT cell antigens reach the circulation and are efficiently metabolised and presented by human liver cells

OBJECTIVE

Mucosal-associated invariant T (MAIT) cells are the most abundant T cells in human liver. They respond to bacterial metabolites presented by major histocompatibility complex-like molecule MR1. MAIT cells exert regulatory and antimicrobial functions and are implicated in liver fibrogenesis. It is not well understood which liver cells function as antigen (Ag)-presenting cells for MAIT cells, and under which conditions stimulatory Ags reach the circulation.

DESIGN

We used different types of primary human liver cells in Ag-presentation assays to blood-derived and liver-derived MAIT cells. We assessed MAIT cell stimulatory potential of serum from healthy subjects and patients with portal hypertension undergoing transjugular intrahepatic portosystemic shunt stent, and patients with inflammatory bowel disease (IBD).

RESULTS

MAIT cells were dispersed throughout healthy human liver and all tested liver cell types stimulated MAIT cells, hepatocytes being most efficient. MAIT cell activation by liver cells occurred in response to bacterial lysate and pure Ag, and was prevented by non-activating MR1 ligands. Serum derived from peripheral and portal blood, and from patients with IBD stimulated MAIT cells in MR1-dependent manner.

CONCLUSION

Our findings reveal previously unrecognised roles of liver cells in Ag metabolism and activation of MAIT cells, repression of which creates an opportunity to design antifibrotic therapies. The presence of MAIT cell stimulatory Ags in serum rationalises the observed activated MAIT cell phenotype in liver. Increased serum levels of gut-derived MAIT cell stimulatory ligands in patients with impaired intestinal barrier function indicate that intrahepatic Ag-presentation may represent an important step in the development of liver disease.

Treatment of refractory subacute cuataneous lupus erythematosus with baricitinib

We report on a patient who presented with refractory subacute cutaneous lupus erythematosus. The scaly annular and polycyclic patches/plaques, and hyperkeratotic lesions on multiple fingers improved rapidly after treatment with baricitinib.

A Surface-Induced Asymmetric Program Promotes Tissue Colonization by Pseudomonas aeruginosa

The opportunistic human pathogen Pseudomonas aeruginosa effectively colonizes host epithelia using pili as primary adhesins. Here we uncover a surface-specific asymmetric virulence program that enhances P. aeruginosa host colonization. We show that when P. aeruginosa encounters surfaces, the concentration of the second messenger c-di-GMP increases within a few seconds. This leads to surface adherence and virulence induction by stimulating pili assembly through activation of the c-di-GMP receptor FimW. Surface-attached bacteria divide asymmetrically to generate a piliated, surface-committed progeny (striker) and a flagellated, motile offspring that leaves the surface to colonize distant sites (spreader). Cell differentiation is driven by a phosphodiesterase that asymmetrically positions to the flagellated pole, thereby maintaining c-di-GMP levels low in the motile offspring. Infection experiments demonstrate that cellular asymmetry strongly boosts infection spread and tissue damage. Thus, P. aeruginosa promotes surface colonization and infection transmission through a cooperative virulence program that we termed Touch-Seed-and-Go.

Quorum-Quenching Human Designer Cells for Closed-Loop Control of Pseudomonas aeruginosa Biofilms

Current antibiotics gradually lose their efficacy against chronic Pseudomonas aeruginosa infections due to development of increased resistance mediated by biofilm formation, as well as the large arsenal of microbial virulence factors that are coordinated by the cell density-dependent phenomenon of quorum sensing. Here, we address this issue by using synthetic biology principles to rationally engineer quorum-quencher cells with closed-loop control to autonomously dampen virulence and interfere with biofilm integrity. Pathogen-derived signals dynamically activate a synthetic mammalian autoinducer sensor driving downstream expression of next-generation anti-infectives. Engineered cells were able to sensitively score autoinducer levels from P. aeruginosa clinical isolates and mount a 2-fold defense consisting of an autoinducer-inactivating enzyme to silence bacterial quorum sensing and a bipartite antibiofilm effector to dissolve the biofilm matrix. The self-guided cellular device fully cleared autoinducers, potentiated bacterial antibiotic susceptibility, substantially reduced biofilms, and alleviated cytotoxicity to lung epithelial cells. We believe this strategy of dividing otherwise coordinated pathogens and breaking up their shielded stronghold represents a blueprint for cellular anti-infectives in the postantibiotic era.

Delboeuf Illusions: Contour or Size Detector Interactions?

Manipulations of contour lightness were shown to alter the magnitude and direction of the Delboeuf illusion. The data suggest that size detector rather than contour interactions create this visual anomaly.

Thiol-dependent peroxidases care little about homology-based assignments of function

Thiol-dependent peroxidase systems are reviewed with special emphasis on their potential use as drug targets. The basic catalytic mechanism of the two major thiol-peroxidase families, the glutathione peroxidases and the peroxiredoxins, are reasonably well understood. Sequence-based predictions of substrate specificities are still unsatisfactory. GPx-type enzymes are not generally specific for GSH but may specifically react with CXXC motifs as present in thioredoxins or tryparedoxins. Inversely, the peroxiredoxin family that was believed to be specific for CXXC-type proteins, also comprises glutathione peroxidases. Since structure-based predictions of function are also limited by small data bases, the increasing number of sequences emerging from genome projects require enzymatic characterization and genetic proof of relevance before they can be classified as drug targets.

Histological, immunohistological, and clinical features of merkel cell carcinoma in correlation to merkel cell polyomavirus status

Merkel cell carcinoma is a rare, but highly malignant tumor of the skin with high rates of metastasis and poor survival. Its incidence rate rises and is currently about 0.6/100000/year. Clinical differential diagnoses include basal cell carcinoma, cyst, amelanotic melanoma, lymphoma and atypical fibroxanthoma. In this review article clinical, histopathological and immunhistochemical features of Merkel cell carcinoma are reported. In addition, the role of Merkel cell polyomavirus is discussed.

Direct and indirect costs of management of long-term warfarin therapy in Canada

BACKGROUND

 Comparisons of overall costs and resource utilization associated with anticoagulation management are important as new alternatives to warfarin are introduced. The aim of the present study was to assess total costs of warfarin-based anticoagulation in different health care models.

METHODS

 Physician- or pharmacist-managed hospital- or community-based anticoagulation clinics in five Canadian provinces were asked to provide itemized information on costs for staff, laboratory, hardware and overheads associated with warfarin management. At each site, cohorts of patients were provided with diaries and participants prospectively entered all costs for warfarin medication and associated health professional contacts, travel to the laboratory, required assistance and time lost from work by patient or caregiver over 3months. All costs were calculated for a 3-month period.

RESULTS

Data from 429 patients at 15 sites were evaluated. The cost from the Ministry of Health perspective ranged from $108 to $199 per 3months in the different settings, the patient costs were $40-$80 and the total societal costs ranged from $188-$244. Sensitivity analyses with typical blood test intervals, the most prescribed strength of warfarin and dispensing fee from another province increased these estimates to $230-$302. When reimbursement for unemployed caregivers was also entered the total cost was $308-$503 per 3months.

CONCLUSIONS

 The total cost for warfarin-based anticoagulation amounted to at least 10 times the lowest cost for the drug. The costs provided should be useful for comparisons with newer drugs without requirement for routine laboratory monitoring and dose adjustments.

YfiBNR mediates cyclic di-GMP dependent small colony variant formation and persistence in Pseudomonas aeruginosa

During long-term cystic fibrosis lung infections, Pseudomonas aeruginosa undergoes genetic adaptation resulting in progressively increased persistence and the generation of adaptive colony morphotypes. This includes small colony variants (SCVs), auto-aggregative, hyper-adherent cells whose appearance correlates with poor lung function and persistence of infection. The SCV morphotype is strongly linked to elevated levels of cyclic-di-GMP, a ubiquitous bacterial second messenger that regulates the transition between motile and sessile, cooperative lifestyles. A genetic screen in PA01 for SCV-related loci identified the yfiBNR operon, encoding a tripartite signaling module that regulates c-di-GMP levels in P. aeruginosa. Subsequent analysis determined that YfiN is a membrane-integral diguanylate cyclase whose activity is tightly controlled by YfiR, a small periplasmic protein, and the OmpA/Pal-like outer-membrane lipoprotein YfiB. Exopolysaccharide synthesis was identified as the principal downstream target for YfiBNR, with increased production of Pel and Psl exopolysaccharides responsible for many characteristic SCV behaviors. An yfi-dependent SCV was isolated from the sputum of a CF patient. Consequently, the effect of the SCV morphology on persistence of infection was analyzed in vitro and in vivo using the YfiN-mediated SCV as a representative strain. The SCV strain exhibited strong, exopolysaccharide-dependent resistance to nematode scavenging and macrophage phagocytosis. Furthermore, the SCV strain effectively persisted over many weeks in mouse infection models, despite exhibiting a marked fitness disadvantage in vitro. Exposure to sub-inhibitory concentrations of antibiotics significantly decreased both the number of suppressors arising, and the relative fitness disadvantage of the SCV mutant in vitro, suggesting that the SCV persistence phenotype may play a more important role during antimicrobial chemotherapy. This study establishes YfiBNR as an important player in P. aeruginosa persistence, and implicates a central role for c-di-GMP, and by extension the SCV phenotype in chronic infections.

During long-term chronic infections of cystic fibrosis patients, Pseudomonas aeruginosa adapts to the lung environment, generating various different morphotypes including small colony variants (SCVs), small, strongly adherent colonies whose appearance correlates with persistence of infection. The SCV morphology is strongly associated with increased levels of the signaling molecule cyclic di-GMP. In this study we investigated the connection between cyclic di-GMP, SCV and persistence of infection. Following a genetic screen for mutants that displayed SCV morphologies, we identified and characterized the YfiBNR system. YfiN is a membrane-bound cyclic di-GMP producing enzyme, whose activity is tightly controlled by YfiR and YfiB. Cyclic di-GMP produced by YfiN boosts exopolysaccharide synthesis, generating an SCV morphotype upon YfiR-mediated release of YfiN repression. The resulting YfiN-mediated SCV morphotype is highly resistant to macrophage phagocytosis in vitro, suggesting a role for the SCV phenotype in immune system evasion. Consistent with this, YfiN de-repression increased the persistence of P. aeruginosa in long-term infections in a mouse model. The observation that the addition of antibiotics decreased the number of suppressors, and the relative fitness disadvantage of the YfiN-mediated SCV morphotype in liquid culture, suggested that SCV-mediated persistence might be favored during antimicrobial chemotherapy.

SCA27 caused by a chromosome translocation: further delineation of the phenotype

We report of a spinocerebellar ataxia (SCA)27 in a daughter and her mother whose karyotype is 46, XX t(5;13)(q31.2;q33.1). The translocation breakpoint is identical in both patients, disrupting the gene-encoding fibroblast growth factor 14 isoform b (FGF14-1b). Clinically, both show signs of SCA, although the daughter is the most affected with early onset cerebellar ataxia, microcephaly, and severe mental retardation. FGF14-1b is the predominant isoform in brain, where it interacts with the voltage gated Na channel. Fgf14(-/-) mice develop ataxia and paroxysmal dyskinesia and have cognitive deficits. One missense and one non-sense mutation in FGF14 have previously been linked to SCA27. Truncation of one allele in our patients suggests that haploinsuffiency of FGF14 can cause SCA27.

N-acetylmuramic acid 6-phosphate lyases (MurNAc etherases): role in cell wall metabolism, distribution, structure, and mechanism

MurNAc etherases cleave the unique D-lactyl ether bond of the bacterial cell wall sugar N-acetylmuramic acid (MurNAc). Members of this newly discovered family of enzymes are widely distributed among bacteria and are required to utilize peptidoglycan fragments obtained either from the environment or from the endogenous cell wall (i.e., recycling). MurNAc etherases are strictly dependent on the substrate MurNAc possessing a free reducing end and a phosphoryl group at C6. They carry a single conserved sugar phosphate isomerase/sugar phosphate-binding (SIS) domain to which MurNAc 6-phosphate is bound. Two subunits form an enzymatically active homodimer that structurally resembles the isomerase module of the double-SIS domain protein GlmS, the glucosamine 6-phosphate synthase. Structural comparison provides insights into the two-step lyase-type reaction mechanism of MurNAc etherases: beta-elimination of the D-lactic acid substituent proceeds through a 2,3-unsaturated sugar intermediate to which water is subsequently added.

Allosteric regulation of histidine kinases by their cognate response regulator determines cell fate

The two-component phosphorylation network is of critical importance for bacterial growth and physiology. Here, we address plasticity and interconnection of distinct signal transduction pathways within this network. In Caulobacter crescentus antagonistic activities of the PleC phosphatase and DivJ kinase localized at opposite cell poles control the phosphorylation state and subcellular localization of the cell fate determinator protein DivK. We show that DivK functions as an allosteric regulator that switches PleC from a phosphatase into an autokinase state and thereby mediates a cyclic di-GMP-dependent morphogenetic program. Through allosteric activation of the DivJ autokinase, DivK also stimulates its own phosphorylation and polar localization. These data suggest that DivK is the central effector of an integrated circuit that operates via spatially organized feedback loops to control asymmetry and cell fate determination in C. crescentus. Thus, single domain response regulators can facilitate crosstalk, feedback control, and long-range communication among members of the two-component network.

[Dynamic transrectal ultrasound (dTRUS): a new method to diagnose anastomotic insufficiency after radical retropubic prostatectomy]

PURPOSE

To prove extravasation after radical retropubic prostatectomy (RRP) nowadays a cystoradiogram is essential. In the present study the diagnostic value of dynamic transrectal ultrasound and cystoradiogram to find an extravasation was compared.

MATERIALS AND METHODS

For detection of an extravasation Cystoradiogram and dTRUS were performed in 250 patients who had undergone RRP. TRUS was performed dynamically, that means that the urinary bladder was filled up with common salt solution backwards by using the transurethral catheter. Anastomosis was inspected by transrectal ultrasound. Detectable extravasation was measured and documented. To verify the results a cystoradiogram was carried out afterwards. In cases of detectable extravasation the results of measurement were compared to the results of dTRUS.

RESULTS

The mean age was 65 years. An extravasation could be detected in 46% within the first 7 days and in 18% after 14 days. At day 21 an extravasation could not be seen in any patient. Seven days postoperative the mean volume of extravasation was 11 ml (3-50 ml) and after 14 days 9 ml (3-25 ml) for dTRUS. For cystoradiogram 12 ml (3-45 ml) and 9 ml (4-23 ml), respectively. The average time until catheter removal was 8 days (5-35 days). 60% of the patients were continent immediately after removing the catheter, 40% were incontinent for not more than 3 months after removal of the catheter (35% ICS I and 5% ICS II). A prolonged urinary incontinence and serious postoperative complications were not observed.

CONCLUSION

Dynamic transrectal ultrasound is a reliable and reasonable method to identify extravasation after RRP. Furthermore radiation exposure (on average 60 cGy/cm(2)/cystoradiogram) can be avoided by replacing the cystoradiogram with dTRUS slips with the dTRUS.

[Comparison of perioperative methylene blue-stained and permanent Papanicolaou-stained urine cytology to detect patients with high-grade urothelial cancer or the urinary bladder. Part 1]

INTRODUCTION

The aim of the study was to investigate whether intraoperative methylene blue-stained and permanent Papanicolaou-stained urine cytologies show comparable accuracy in detection of high-grade urothelial carcinoma.

PATIENTS AND METHODS

The study included 130 patients; 50 patients were without malignancy (25 follow-up, 25 with hematuria). In 80 patients transurethral resection due to urothelial carcinoma was performed. Per patient two cytology specimens were prepared: one immediate methylene blue-stained specimen, which was evaluated by the surgeon, and one Papanicolaou-stained permanent cytology slide, which was blinded and evaluated by one urologist.

RESULTS

Cytology results of all patients without malignancy were unsuspicious irrespective of the staining method. Of 80 patients with urothelial carcinoma, 50 showed a low-grade tumor. Sensitivity of tumor detection was 20 and 30% for methylene blue/Papanicolaou-stained slides, respectively. Among 30 patients with high-grade carcinoma, 10 were detected by methylene blue cytology and 30 by Papanicolaou-stained slides, corresponding to a sensitivity of 40 and 100%, respectively.

CONCLUSIONS

The results of standard Papanicolaou-stained urine cytology in the detection of clinically relevant high-grade urothelial carcinoma are excellent. The quality of cytological tumor detection by methylene blue-stained cytology made by different evaluators is insufficient in our opinion.

[High-dose rate brachytherapy for high-risk prostate cancer]

To estimate disease-free survival it is necessary to allocate patients into tumor risk groups: locally advanced prostate carcinoma with extracapsular spread or localized prostate carcinoma of tumor stage T2c or one of the risk factors PSA >20 or Gleason > or =8 apply for the high-risk group. Intermediate-risk carcinomas are those belonging to tumor stage T2b or with PSA >10-20 or Gleason 7. Particularly for patients with intermediate and high-risk disease early PSA relapse is of major interest. This phenomenon could be a consequence of current inadequate imaging of lymph node or bone metastasis or as a consequence subclinical metastatic spread remains undetectable during radical treatment. However, tumor biology itself could lead to the progression of the disease in the high-risk group. As a consequence, risk-adapted therapy is very important in these cases. The applied radiation dose plays an important role in radiotherapy. Several publications have shown that the biochemical relapse correlates with the generally accepted risk factors and the radiation dose. Regarding this, high-quality treatment planning and HDR brachytherapy combined with EBRT (external beam radiation therapy) leads to good treatment results in selected groups. So far in our own experience, HDR brachytherapy in combination with EBRT is a successful form of treatment with few acute and late side effects in the first 42 patients examined. First results concerning to PSA relapse-free time, quality of life, miction, and erectile function are promising.

MurQ Etherase is required by Escherichia coli in order to metabolize anhydro-N-acetylmuramic acid obtained either from the environment or from its own cell wall

MurQ is an N-acetylmuramic acid-phosphate (MurNAc-P) etherase that converts MurNAc-P to N-acetylglucosamine-phosphate and is essential for growth on MurNAc as the sole source of carbon (T. Jaegar, M. Arsic, and C. Mayer, J. Biol. Chem. 280:30100-30106, 2005). Here we show that MurQ is the only MurNAc-P etherase in Escherichia coli and that MurQ and AnmK kinase are required for utilization of anhydro-MurNAc derived either from cell wall murein or imported from the medium.

Scission of the lactyl ether bond of N-acetylmuramic acid by Escherichia coli "etherase"

The ubiquitous bacterial cell wall sugar N-acetylmuramic acid (MurNAc) carries a unique D-lactyl ether substituent at the C3 position. Recently, we proposed an etherase capable of cleaving this lactyl ether to be part of the novel bacterial MurNAc dissimilation pathway (Dahl, U., Jaeger, T., Nguyen, B. T., Sattler, J. M., Mayer, C. (2004) J. Bacteriol. 186, 2385-2392). Here, we report the identification of the first known MurNAc etherase. The encoding gene murQ is located at 55 min on the Escherichia coli chromosome adjacent to murP, the MurNAc-specific phosphotransferase system. A murQ deletion mutant could not grow on MurNAc as the sole source of carbon and energy but could be complemented by expressing murQ from a plasmid. The mutant had no obvious phenotype when grown on different carbon sources but accumulated MurNAc 6-phosphate at millimolar concentrations from externally supplied MurNAc. Purified MurQ-His6 fusion protein and extracts of cells expressing murQ both catalyze the cleavage of MurNAc 6-phosphate, with GlcNAc 6-phosphate and D-lactate being the primary products. The 18O label from enriched water is incorporated into the sugar molecule, showing that the C3-O bond is cleaved and reformed by the enzyme. Moreover, an intermediate was detected and identified as an unsaturated sugar molecule. Based on this observation, we suggested a lyase-type mechanism (beta-elimination/hydration) for the cleavage of the lactyl ether bond of MurNAc 6-phosphate. Close homologs of murQ were found on the chromosome of several bacteria, and amino acid sequence similarity with the N-terminal domain of human glucokinase-regulatory protein (GckR or GKRP) was recognized.

Identification of a phosphotransferase system of Escherichia coli required for growth on N-acetylmuramic acid

We report here that wild-type Escherichia coli grows on N-acetylmuramic acid (MurNAc) as the sole source of carbon and energy. Analysis of mutants defective in N-acetylglucosamine (GlcNAc) catabolism revealed that the catabolic pathway for MurNAc merges into the GlcNAc pathway on the level of GlcNAc 6-phosphate. Furthermore, analysis of mutants defective in components of the phosphotransferase system (PTS) revealed that a PTS is essential for growth on MurNAc. However, neither the glucose-, mannose/glucosamine-, nor GlcNAc-specific PTS (PtsG, ManXYZ, and NagE, respectively) was found to be necessary. Instead, we identified a gene at 55 min on the E. coli chromosome that is responsible for MurNAc uptake and growth. It encodes a single polypeptide consisting of the EIIB and C domains of a so-far-uncharacterized PTS that was named murP. MurP lacks an EIIA domain and was found to require the activity of the crr-encoded enzyme IIA-glucose (EIIA(Glc)), a component of the major glucose transport system for growth on MurNAc. murP deletion mutants were unable to grow on MurNAc as the sole source of carbon; however, growth was rescued by providing murP in trans expressed from an isopropylthiogalactopyranoside-inducible plasmid. A functional His(6) fusion of MurP was constructed, isolated from membranes, and identified as a polypeptide with an apparent molecular mass of 37 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis. Close homologs of MurP were identified in the genome of several bacteria, and we believe that these organisms might also be able to utilize MurNAc.

Similarity and lightness effects in Ebbinghaus illusion created by keyboard characters

36 observers judged the size of a central S in variants of the Ebbinghaus figure having contextual Ss, $s, or Hs. When the figures were composed of similarly shaped elements, underestimation of the central S was obtained. Manipulations of lightness indicated that these underestimations were strongest for figures with gray contextual characters and a black central S and weakest for figures with black contextual characters and a gray central S. All black or all gray figures produced intermediate illusions. The data are consistent with Choplin and Medin's 1999 claim that figural properties rather than semantic similarity influences size contrast and further show that the visual processes underlying size contrast include interactions of contours.

The role of complement, antibody, and tumor necrosis factor alpha in the killing of Plasmodium falciparum by the monocytic cell line THP-1

Killing of Plasmodium falciparum blood forms by the differentiated human myelomonocytic THP-1Mo cell line was studied by a radiometric assay. Results showed that parasite killing was promoted by complement, antimalarial antibody, and the cytokines tumor necrosis factor alpha and gamma interferon. Differentiated THP-1Mo appears to be a useful monocytic cell line for the study of mechanisms of immunity to Plasmodium.

Enhancement of neutrophil-mediated killing of Plasmodium falciparum asexual blood forms by fatty acids: importance of fatty acid structure

Effects of fatty acids on human neutrophil-mediated killing of Plasmodium falciparum asexual blood forms were investigated by using a quantitative radiometric assay. The results showed that the antiparasitic activity of neutrophils can be greatly increased (>threefold) by short-term treatment with fatty acids with 20 to 24 carbon atoms and at least three double bonds. In particular, the n-3 polyenoic fatty acids, eicosapentaenoic and docosahexaenoic acids, and the n-6 fatty acid, arachidonic acid, significantly enhanced neutrophil antiparasitic activity. This effect was >1.5-fold higher than that induced by an optical concentration of the known agonist cytokine tumor necrosis factor alpha (TNF-alpha). At suboptimal concentrations, the combination of arachidonic acid and TNF-alpha caused a synergistic increase in neutrophil-mediated parasite killing. The fatty acid-induced effect was independent of the availability of serum opsonins but dependent on the structure of the fatty acids. The length of the carbon chain, degree of unsaturation, and availability of a free carboxyl group were important determinants of fatty acid activity. The fatty acids which increased neutrophil-mediated killing primed the enhanced superoxide radical generation of neutrophils in response to P. falciparum as detected by chemiluminescence. Scavengers of oxygen radicals significantly reduced the fatty acid-enhanced parasite killing, but cyclooxygenase and lipoxygenase inhibitors had no effect. These findings have identified a new class of immunoenhancers that could be exploited to increase resistance against Plasmodium species.

GM-CSF-induced priming of human neutrophils for enhanced phagocytosis and killing of asexual blood stages of Plasmodium falciparum: synergistic effects of GM-CSF and TNF

Granulocyte macrophage-colony stimulation factor (GM-CSF), which is a haematopoietic cytokine generated by activated T lymphocytes and macrophages during infection, was investigated for its effects on human neutrophil-mediated killing of asexual blood forms of Plasmodium falciparum. Pretreatment of neutrophils with human recombinant-GM-CSF markedly increased the parasite killing (measured by a radiometric assay), in the presence of normal serum (containing complement), immune serum (IS), purified IgG (from IS) or heat inactivated IS. GM-CSF pretreatment also enhanced phagocytosis of the parasite by neutrophils and the expression of CR3, Fc gamma RII and Fc gamma RIII receptors. Treatment of neutrophils with a combination of GM-CSF and TNF resulted in a synergistic increase in phagocytosis and killing of the parasite. The findings suggest that GM-CSF is likely to form part of the cytokine network responsible for regulating the antiparasitic activity of the neutrophil in malaria.

Note on the ontogeny of assimilative illusions: a reply to Pressey (1987)

It is argued that a previous study showing the parallel lines illusion is stronger in adulthood than in adolescence or old age is methodologically sound. Further, this finding does not necessitate a defense of assimilation theory based on epistemology that links the phenomenal properties of illusions to the techniques of measurement. Rather, it is suggested that Pressey's 1974 and 1987 hypothesis that all illusions of assimilation decline from childhood to adulthood mistakenly extends the decrement into adulthood when in fact the decrement occurs only between the ages of 6 and 10 years.

Contour lightness and separation effects in the Ebbinghaus illusion

For 48 observers, the central circle of Ebbinghaus figures appeared smaller as the separation between it and the contextual circles increased. Lightness of the contours only affected the illusion when the contextual circles were large and located close to the central circle. An explanation incorporating size contrast and attraction between contours was offered.

Effects of cytokines, complement, and antibody on the neutrophil respiratory burst and phagocytic response to Plasmodium falciparum merozoites

The interaction between Plasmodium falciparum merozoites and human neutrophils, as well as the role of cytokines, complement, and antimalarial antibody on this interaction, was examined in vitro by measuring luminol-dependent chemiluminescence and phagocytosis. Merozoites, in the presence of heat-inactivated (56 degrees C/30 min) normal serum, had very little effect on the neutrophil chemiluminescence. This response was significantly enhanced by the addition of normal serum (containing normal complement activity). In the presence of serum or plasma containing anti-P. falciparum antibodies (IS) with no detectable complement activity, the merozoites induced a marked response characterized by an increase in initial peak rate of chemiluminescence and a sustained increased rate of chemiluminescence. However, this response was not further increased if IS containing complement activity was used. Pretreatment of neutrophils with either tumor necrosis factor alpha, lymphotoxin, or gamma interferon significantly increased the neutrophil response to IS-treated merozoites, reflected in an increased initial peak rate and sustained increased rate of chemiluminescence. The effects of cytokine treatment of neutrophils and IS opsonization of merozoites were synergistic. In association with the changes in the chemiluminescence responses, IS was shown to promote phagocytosis of merozoites by neutrophils, and this event was further increased by treating neutrophils with the cytokines. The results emphasize the importance of antibody and cytokines in neutrophil-mediated damage of P. falciparum merozoites.

[CPM treatment of the shoulder joint]

Since Salter's results about experimental continuous passive motion (CPM) there are remarkable, generally positive experiences on CPM-treatment of the knee-joint. Now CPM-experiences on shoulder joints are described based on data from 150 patients during the last six years. Three types of motorized CPM-machines are presented for the treatment of the shoulder joint. At the present time they are components of the so-called "Artromot-System." Indications and applications of the CPM-devices are described. Patients are accepting the new way of treatment promptly, because they could apply the devices during the early postoperative period for hours in a selected range of motion, causing no pain. The duration of the CPM-treatment should be two to four hours a day. As shown by Salter's experimental studies the continuous passive motion enhances the metabolism of a joint, improves the resorption of effusions, and may prevent joint stiffness as well as secondary arthrosis. CPM-treatment can especially be prolonged for outpatients; thus CPM treatment can contribute to shorten the hospital stay and the time of treatment in general showing an economic factor.

[Arthrolysis of the knee joint]

This publication consists of two parts, the first of which is concerned with the definition of arthrolysis as a mere soft tissue procedure. This is delineated from arthroplasty. In the second part, arthrolysis results are presented. Three different means of treatment are possible for knee joint stiffness: manual joint mobilization under anaesthesia, arthroscopic operation, and "open" arthrolysis. The authors concentrate on the third type of treatment because of the great amount of long-term experience they have made. In the majority of cases knee joint stiffness is caused by immobilization and posttraumatic and postoperative effects on the joint itself or in the area of the joint. Morphological findings are intraarticular adhesions in the recessus, as well as between the joint surfaces, retraction of the capsular-ligament system, and extra-articularly located impediments caused by shrinkage and scars in the muscles, tendons, and sliding laminas of the soft tissue. Open arthrolysis is indicated after failure of conservative treatment and in cases of severe stiffness of the knee joint. For operative arthrolysis many requirements must be met, which are specified in detail. The preoperative information about the treatment given to the patient is of particular interest. The operative methods, including postoperative management, are described only briefly, because the presentation of the results is the main purpose of this paper. Eighty-five patients (94%) who underwent open arthrolysis were personally examined. Information about the other patients was obtained from medical records such as the examination at discharge or the last presentation in the outpatient clinic. The average follow-up time was 5 years and 4 months ranging from 6 months to 14.25 years. The results are differentiated in many respects whereas the so-called relative improvement of joint mobility following an operation is of main interest. Well-defined criteria have been published and were applied. The results are listed according to the severity of joint stiffness. Four grades of joint stiffness are created, ranging from grade IV, the most severe form with a preoperative maximum of joint mobility of 30 degrees, to grade I with a maximum of 90 degrees joint mobility. In all, operative procedures led to an improvement in nearly 100% compared to the preoperative findings. The results are presented in relation to age, operative methods, previous operations, and different stages during the follow-up.

The type I/type II perceptual dichotomy: a reanalysis for the illusions of extent

The categorization of geometrical illusions of extent as Type I or Type II phenomena based on variation in magnitude with age is critically examined. Methodological shortcomings and the failure of contemporary findings to show matching age trends for components of a single illusion are presented as factors undermining the usefulness of this perceptual dichotomy. Finally, it is shown that a new Type I/Type II dichotomy based on changes in perceived size rather than amount of illusion indicates a developmental commonality among most of the illusions of extent.

Life-span ontogeny of the parallel-lines illusion

The magnitude of two assimilative and one contrastive version of the parallel-lines illusion was measured using 72 observers whose ages ranged in years from the teens to the seventies. Only the overestimated assimilative illusion varied significantly with age, producing smaller misestimations in both youth and old age and a maximal distortion in the 50s. This quadratic trend duplicated the adult-age course of the overestimated Müller-Lyer illusion thereby reinforcing the belief that the two are kindred visual anomalies. As with the Müller-Lyer, the ontogeny of the parallel-lines illusion is best explained by age-induced changes in the vigor of contour interactions.

Contextual effects in the parallel lines illusion: some implications for assimilation theory

32 undergraduates participated in each of two experiments designed to determine how structural manipulations of the parallel lines figure affect the resulting illusion. Collectively and for the range of figures studied, the data show progressive elongations of the contextual lines of the illusion figure first increase, then decrease, the apparent length of the judged line; the misestimation of the length of the judged line diminishes as the separation between it and shorter contextual lines increases; and variations in contour lightness significantly affect the illusion when the contextual lines are shorter than and at any distance from the judged line or when the contextual lines are slightly longer than and at an intermediate distance from the judged line. These data indicate that size-assimilation, as well as size-contrast processes, contributes to the parallel lines illusion and that the assimilation process must be mediated by both sensory and cognitive activity in the visual system.

Assimilation and contrast in the parallel lines illusion?

Judgments of 40 undergraduates indicated that the assimilative character of the parallel lines illusion was destroyed at large values of both context line length and separation of context and center line variables. Accommodation of a portion of these results requires a modification of Brigner's (1977) theory of perception of illusory extent.

Exposure duration and line length: an analogy to the Broca-Sulzer effect in perception of extent?

For 30 undergraduates, brief exposures were shown to increase the apparent length of a line. This enhancement of length diminished as duration of exposure increased, creating an illusion of line length that resembles the Broca-Sulzer brightness anomaly.

Delboeuf illusions: contour or size detector interactions?

Manipulations of contour lightness were shown to alter the magnitude and direction of the Delboeuf illusion. The data suggest that size detector rather than contour interactions create this visual anomaly.