Initiation of H1-T6SS dueling between Pseudomonas aeruginosa.

The Type VI secretion system (T6SS) is a multicomponent apparatus, present in many Gram-negative bacteria, which can inhibit bacterial prey in various ecological niches. Pseudomonas aeruginosa assembles one of its three T6SS (H1-T6SS) to respond to attacks from adjacent competing bacteria. Surprisingly, repeated assemblies of the H1-T6SS, termed dueling, were described in a monoculture in the absence of an attacker strain; however, the underlying mechanism was unknown. Here, we explored the role of H2-T6SS of P. aeruginosa in triggering H1-T6SS assembly. We show that H2-T6SS inactivation in P. aeruginosa causes a significant reduction in H1-T6SS dueling and that H2-T6SS activity directly triggers retaliation by the H1-T6SS. Intraspecific competition experiments revealed that elimination of H2-T6SS in non-immune prey cells conferred protection from H1-T6SS. Moreover, we show that the H1-T6SS response is triggered independently of the characterized lipase effectors of the H2-T6SS, as well as those of Acinetobacter baylyi and Vibrio cholerae. Our results suggest that H1-T6SS response to H2-T6SS in P. aeruginosa can impact intraspecific competition, particularly when the H1-T6SS effector-immunity pairs differ between strains, and could determine the outcome of multistrain colonization.IMPORTANCEThe opportunistic pathogen Pseudomonas aeruginosa harbors three different Type VI secretion systems (H1, H2, and H3-T6SS), which can translocate toxins that can inhibit bacterial competitors or inflict damage to eukaryotic host cells. Unlike the unregulated T6SS assembly in other Gram-negative bacteria, the H1-T6SS in P. aeruginosa is precisely assembled as a response to various cell damaging attacks from neighboring bacterial cells. Surprisingly, it was observed that neighboring P. aeruginosa cells repeatedly assemble their H1-T6SS toward each other. Mechanisms triggering this "dueling" behavior between sister cells were unknown. In this report, we used a combination of microscopy, genetic and intraspecific competition experiments to show that H2-T6SS initiates H1-T6SS dueling. Our study highlights the interplay between different T6SS clusters in P. aeruginosa, which may influence the outcomes of multistrain competition in various ecological settings such as biofilm formation and colonization of cystic fibrosis lungs.

Type 6 secretion dynamics within and between bacterial cells.

The bacterial type 6 secretion system (T6SS) functions as a virulence factor capable of attacking both eukaryotic and prokaryotic target cells by a process that involves protein transport through a contractile bacteriophage tail-like structure. The T6SS apparatus is composed, in part, of an exterior sheath wrapped around an interior tube. Here, we report that in living cells the cytoplasmic adenosine triphosphatase called ClpV specifically recognizes the contracted T6SS sheath structure, causing its disassembly within seconds. ClpV imaging allowed spatial and temporal documentation of cell-cell interactions (termed T6SS dueling) that likely mark the location of repeated T6SS-mediated protein translocation events between bacterial cells.

How positive and negative expectations shape the experience of visceral pain: an experimental pilot study in healthy women.

BACKGROUND: In order to elucidate placebo and nocebo effects in visceral pain, we analyzed the effects of positive and negative expectations on rectal pain perception, rectal pain thresholds, state anxiety and cortisol responses in healthy women. METHODS: Painful rectal distensions were delivered at baseline, following application of an inert substance combined with either positive instructions of pain relief (placebo group, N = 15), negative instructions of pain increase (nocebo group, N = 17), or neutral instructions (control, N = 15). Perceived pain intensity, unpleasantness/aversion and urge-to-defecate, state anxiety and serum cortisol were determined at baseline, immediately following group-specific instructions and on a second study day after the same instructions (test day). Rectal pain thresholds were determined at baseline and on the test day. KEY RESULTS: Whereas perceived pain intensity was significantly decreased in the placebo group, the nocebo group revealed significantly increased pain intensity ratings, along with significantly greater anticipatory anxiety on the test day (all P < 0.05 vs controls). Cortisol concentrations were significantly increased in the nocebo group following treatment but not on the test day. CONCLUSIONS & INFERENCES: The experience of abdominal pain can be experimentally increased or decreased by inducing positive or negative expectations. Nocebo effects involve a psychological stress response, characterized by increased anticipatory anxiety. These findings further underscore the role of cognitive and emotional factors in the experience of visceral pain, which has implications for the pathophysiology and treatment of patients with chronic abdominal complaints.

Type VI secretion requires a dynamic contractile phage tail-like structure.

Type VI secretion systems are bacterial virulence-associated nanomachines composed of proteins that are evolutionarily related to components of bacteriophage tails. Here we show that protein secretion by the type VI secretion system of Vibrio cholerae requires the action of a dynamic intracellular tubular structure that is structurally and functionally homologous to contractile phage tail sheath. Time-lapse fluorescence light microscopy reveals that sheaths of the type VI secretion system cycle between assembly, quick contraction, disassembly and re-assembly. Whole-cell electron cryotomography further shows that the sheaths appear as long tubular structures in either extended or contracted conformations that are connected to the inner membrane by a distinct basal structure. These data support a model in which the contraction of the type VI secretion system sheath provides the energy needed to translocate proteins out of effector cells and into adjacent target cells.

[Vitamin B6-sensitive hereditary sideroblastic anemia]. / Vitamin-B6-sensible hereditäre sideroblastische Anämie.

HISTORY: A 30-year-old patient was admitted for investigation of microcytotic, hypochromic anemia (hemoglobin 8.3 g/dl) with splenomegaly. INVESTIGATIONS: Bone marrow smear showed a normocellular marrow with augmented severely dysplastic erythropoesis. Prussian-blue staining revealed an increased number of ring sideroblasts, thus myelodysplastic syndrome (refractory anemia with ringsideroblasts) was suspected. DIAGNOSIS AND TREATMENT: Review of former laboratory values and investigations of the patient's family revealed the correct diagnosis of x-linked sideroblastic anemia (XLSA). The patient was treated with oral pyridoxine. Hemoglobin levels steadily increased, so the diagnosis of pyridoxine-responsive sideroblastic anemia was made. Liver biopsy showed secondary fibrosis with beginning cirrhosis due to iron overload. Therapy with deferoxamine and phlebotomies was initiated. CONCLUSION: XLSA is a rare differential diagnosis of acquired forms of sideroblastic anemias. A high degree of clinical suspicion is necessary for diagnosis because morphological studies such as histology and cytology may not yield conclusive results. A correct diagnosis is especially important because of the uncomplicated therapeutic options.

An evaluation of two concentrations of hyaluronidase for supplementation of peribulbar anaesthesia.

We studied the effect of the addition of hyaluronidase to a mixture of lignocaine 2% and bupivacaine 0.75% for peribulbar anaesthesia in 60 patients presenting for elective intra-ocular surgery. Using a randomised, double-blind design, patients were allocated to one of three groups: no hyaluronidase (group A) (n = 20); hyaluronidase 50 iu.ml-1 (group B) (n = 20); hyaluronidase 150 iu.ml-1 (group C) (n = 20). The speed of onset of the block, the presence of akinesia, analgesia and the need for supplementary injections were assessed. The addition of 150 iu.ml-1 of hyaluronidase resulted in a mean (SEM) time to akinesia of 9.2 (0.9) min compared to 10.9 (0.9) min in the control group and 10.7 (1.1) min in those receiving the lower dose. Fewer patients in group C required a further injection (20%) than those in groups A (40%) or B (45%). None of the findings were statistically significant. Hyaluronidase was not associated with any complications.

DNA polymorphism of the major histocompatibility class I genes and their association with serologically defined haplotypes.

DNA of unrelated persons as well as members of families that were totally or partially homozygous or completely heterozygous on the loci of the major histocompatibility class I genes has been isolated from peripheral blood lymphocytes and blot hybridized with the class I pseudogene pHLA 12.4 probe. The autoradiographic DNA patterns were discussed and compared with well-defined serological features. Positive associations with serologically typed alleles had been demonstrated for HLA-A1,11; -A2; -A3; -B7; -B14; -B35; -Bw41; and -Cw5.

Evidence for a "new" allele at the esterase D (E.C. 3.1.1.1.) locus.

An apparently new EsD gene product (EsD*Düsseldorf) was detected by use of horizontal agarose gel electrophoresis (AGE), starch gel electrophoresis (SGE), and isoelectric focusing (IEF). The observed phenotype EsD (1-Düsseldorf) can be distinguished from any known EsD type.

[Unusual Gm-haplotypes possibly due to crossing over]. / Uber ungewöhnliche Gm-Haplotypen, die vermutlich durch Crossing-over entstanden sind.

Four cases are introduced with unusual Gm-haplotypes. Their possible origin is discussed as being either intra- and intergenic or unequal cross over. The last case shows deletions of either y1 or y3 -cistrons due to unequal cross over.

Polymorphism of the human phosphoglycolate phosphatase in Northrhine-Westphalia (F.R.G.) and its application to paternity testing.

Blood samples from 563 unrelated German and from 110 Turkish individuals living in the Düsseldorf area were studied for phosphoglycolate phosphatase polymorphism. The distribution of the observed phenotypes in the population genetic study did not diverge from the expected values according to Hardy-Weinberg law. In our series, the gene frequencies were calculated as follows: (a) Germans: PGP1 = 0.851, PGP2 = 0.118, PGP3 = 0.031, (b) Turks: PGP1 = 0.973, PGP2 = 0.018, PGP3 = 0.009. The assumed autosomal codominant mode of inheritance was confirmed by the examination of 109 mother-child pairs and by analysis of 70 cases of disputed paternity. The plausibility to exclude German non-fathers from paternity is 12.78%.

Further data on the development of red blood cell antigens Lua, Lub, and Cob.

One hundred and fifty-five cord cells were tested for the red blood cell antigens Lua, Lub and Cob in order to collect data on the early postnatal expression of these markers. Additionally, dosage studies were carried out in 8 - 10-month-old heterozygous children. Antigens Lua and Lub revealed to be significantly less expressed in children of both ages compared with those of their mothers, whereas no such differences could be demonstrated in the expression of the antigen Cob.

Subacute sclerosing panencephalitis in a brother and sister. Therapeutic trial of fibroblast interferon.

This paper describes the very rare occurrence of subacute sclerosing panencephalitis (SSPE) in two siblings: a Turkish boy and his younger sister. The clinical picture was characteristic, and the diagnosis was confirmed in both cases by appropriate laboratory examination. The interval between the occurrence of the first neurological symptoms in the boy, and subsequently in the girl was four years. Study of HLA- and 27 other polymorphic marker-systems did not reveal linkage to one of the systems tested. Therapeutic trials in the girl included intravenous and intraventricular application of a total of 87 X 10(6) U human fibroblast interferon (Hu INF-beta) over 21 days. However, up to 3 months after the end of interferon administration there were no significant changes in the girl's condition.