Requirements of acetyl phosphate for the binding protein-dependent transport systems in Escherichia coli.

In Escherichia coli, acetyl phosphate can be formed from acetyl-CoA via the phosphotransacetylase (phosphate acetyltransferase; acetyl-CoA:orthophosphate acetyltransferase, EC 2.3.1.8) reaction and from acetate (plus ATP) via the acetate kinase (ATP:acetate phosphotransferase, EC 2.7.2.1) reaction. By restricting acetyl phosphate formation to the phosphotransacetylase reaction alone, through the use of metabolic inhibitors, we were able to show that, with pyruvate as a source of energy, mutants defective in phosphotransacetylase are unable to transport glutamine, histidine, and methionine. However, with the same energy source, mutants defective in acetate kinase are normal in the transport of these amino acids. The inability of the phosphotransacetylase mutants to transport is due to their presumed inability to form acetyl phosphate, because pyruvate is found to be metabolized to acetyl-CoA in these mutants. Thus acetyl phosphate has been implicated in active transport. Evidence is also presented that neither the protonmotive force nor the ecf gene product is required for the shock-sensitive transport systems.     

Aberrant actin depolymerization triggers the pyrin inflammasome and autoinflammatory disease that is dependent on IL-18, not IL-1β

Gain-of-function mutations that activate the innate immune system can cause systemic autoinflammatory diseases associated with increased IL-1β production. This cytokine is activated identically to IL-18 by an intracellular protein complex known as the inflammasome; however, IL-18 has not yet been specifically implicated in the pathogenesis of hereditary autoinflammatory disorders. We have now identified an autoinflammatory disease in mice driven by IL-18, but not IL-1β, resulting from an inactivating mutation of the actin-depolymerizing cofactor Wdr1. This perturbation of actin polymerization leads to systemic autoinflammation that is reduced when IL-18 is deleted but not when IL-1 signaling is removed. Remarkably, inflammasome activation in mature macrophages is unaltered, but IL-18 production from monocytes is greatly exaggerated, and depletion of monocytes in vivo prevents the disease. Small-molecule inhibition of actin polymerization can remove potential danger signals from the system and prevents monocyte IL-18 production. Finally, we show that the inflammasome sensor of actin dynamics in this system requires caspase-1, apoptosis-associated speck-like protein containing a caspase recruitment domain, and the innate immune receptor pyrin. Previously, perturbation of actin polymerization by pathogens was shown to activate the pyrin inflammasome, so our data now extend this guard hypothesis to host-regulated actin-dependent processes and autoinflammatory disease.Autoinflammatory syndromes are caused by dysregulation of the innate immune system, frequently affecting the inflammasome or other pathogen recognition pathways and leading to the overproduction of active IL-1β and IL-18 (Masters et al., 2009). To date, there are at least 12 known genetic causes of autoinflammatory disease, including familial Mediterranean fever (FMF), hyper-IgD syndrome, and cryopyrin-associated periodic syndrome. Therapeutic options for these diseases include nonsteroidal antiinflammatory drugs, corticosteroids, colchicine (for FMF), anti-TNF, and direct blockade of IL-1, which can be highly efficacious (Masters et al., 2009; Caso et al., 2013). IL-18 and IL-1β are produced in many cells, including monocytes and macrophages (Okamura et al., 1995; Ushio et al., 1996). IL-18 and IL-1β are produced as precursors and do not have a signal peptide to facilitate their secretion; instead, they are activated and released extracellularly as mature proteins after cleavage by caspase-1 (Li et al., 1995; Ghayur et al., 1997; Gu et al., 1997). Despite these similarities, there is no known hereditary autoinflammatory disease where the pathology is caused exclusively by IL-18.The inflammasome is an intracellular molecular platform that forms in response to pathogen- or danger-associated molecular patterns (DAMPs), leading to recruitment and activation of caspase-1 (Martinon et al., 2002; Schroder and Tschopp, 2010). A growing number of inflammasomes have been reported, each nucleated by a different innate immune receptor, such as NLRP1 (Martinon et al., 2000; Boyden and Dietrich, 2006), NLRP3 (Agostini et al., 2004), NLRC4 (Franchi et al., 2006), pyrin (Chae et al., 2011), and AIM2 (Hornung et al., 2009). Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) is a key adaptor used by most of these innate immune receptors to interact with and recruit caspase-1 (Srinivasula et al., 2002). Activating mutations in NLRP3 result in increased IL-1β and IL-18 production, which can be prevented in mice by deleting caspase-1 or ASC. Furthermore, deleting either the IL-18R or the IL-1R can both independently protect mice from this NLRP3-mediated autoinflammatory disease (Brydges et al., 2013). For the FMF protein, pyrin, activating mutations induce ASC-dependent but NLRP3-independent IL-1β activation and cause severe autoinflammation in mice (Chae et al., 2011). Interestingly, pyrin interacts with ASC, microtubules, and actin filaments (Mansfield et al., 2001; Richards et al., 2001; Waite et al., 2009), and it has recently been shown that modification of RhoGTPases by bacterial toxins can trigger the pyrin inflammasome, perhaps via modulation of actin dynamics (Xu et al., 2014). This raises the fascinating prospect of a link between perturbations in the actin cytoskeleton and autoinflammatory disease.Wdr1 is required for disassembly of actin filaments in conjunction with the actin-depolymerizing factor/cofilin family of proteins. Mice homozygous for a hypomorphic allele of Wdr1 (Wdr1^rd/rd) exhibit spontaneous autoinflammatory disease and thrombocytopenia (Kile et al., 2007). Both defects have been suggested to result from a disruption in actin dynamics. Thrombocytopenia results from defects in megakaryocytes, a cell type that is entirely dependent on a functional cytoskeleton to shed platelets (Patel et al., 2005). Wdr1 mutant mice also exhibit neutrophilia; however, the critical inflammatory mediators and cell types important for the development of inflammation in this genetic condition are unclear (Kile et al., 2007). Intriguingly, Wdr1 was found to be secreted after caspase-1 activation (Keller et al., 2008).We examined the role of key inflammatory mediators that drive autoinflammation in Wdr1^rd/rd mice and demonstrated that this disease is IL-18 dependent, but IL-1 independent. As expected, this IL-18 is produced by the inflammasome; however, it is not produced from neutrophils or macrophages, but instead only from monocytes. Finally, we found that the autoinflammatory disease was mediated by pyrin, providing evidence that this innate immune receptor recognizes alterations in the actin polymerization pathway.     

Implicit sequence learning processes after unilateral stroke

Implicit learning is durable over time, robust under psychological stress and shows specificity of transfer; characteristics that may be beneficial in stroke rehabilitation. The purpose of this study was to investigate implicit sequence learning processes in unilateral stroke using an extended number of trial blocks in a serial reaction time task (SRTT). Previous research, using a SRTT, has produced equivocal results that may be associated with the small number of trial blocks used. Seven adults, at least one year after stroke, and eight controls performed 54 blocks of a modified SRTT over two weeks. Participants responded with a finger key press during acquisition and retention and with a whole arm movement during transfer. Response times in milliseconds were used to measure learning. The stroke group performed more slowly than the controls during all experimental phases. Response times for both groups decreased with practice of the repeating sequence, increased with introduction of a random sequence, and decreased when reintroduced to the repeating sequence of the SRTT. Both groups demonstrated delayed retention of knowledge of the sequence over a two-week period and exhibited specificity of transfer. These data suggest that with extended practice people with unilateral stroke are able to learn implicitly.     

Religiosity/Spirituality and Behavioral Medicine: Investigations Concerning the Integration of Spirit with Body

This article introduces the special section on Religiosity/Spirituality and Behavioral Medicine. After brief comments on the increase in interest in this topic and related definition concerns, each of the five articles that comprise the special section is presented.     

The impact of a change in work posture from seated to stand‐up on work‐related musculoskeletal disorders among sewing‐machine operators

Background

Work‐related postural change could lead to improved musculoskeletal health.

Method(s)

In a quantitative, retrospective, longitudinal study, data of work‐related musculoskeletal disorders of 123 sewing‐machine operators were captured for 4.5 years, and analysed using Poisson regression.

Results

Stand‐up work posture (SUWP) reduced the incidence for spinal disorders (SD) to 0.29 fold the incidence for sitting work posture (SWP) (P < 0.001). Morbid obesity had significantly increased (P = 0.04) incidence of upper limb disorders (ULD), 3.35 times that of normal body mass index (BMI) (regardless of work posture). SUWP was associated with increased IRR (1.49) for lower limb disorders (LLD). LLDs were associated with obesity (overweight (IRR = 2.58; P = 0.08), obese (IRR = 2.45; P = 0.09), and morbidly obese (IRR = 6.24; P = 0.001)).

Conclusions

The protective benefit of the SUWP was statistically significant for SD incidence. Owing to high mean BMI, SUWP had a negative impact on the incidence of LLDs for the first 2 months.

     

The colitis of Behcet's disease: A separate entity?

Summary An additional case of Behcet's disease with colonic involvement has been presented. This association is rare, as only 13 prior cases with adequate data were available for comparison. Controversy exists as to whether these cases represented true involvement of the colon by Behcet's disease, coincidental inflammatory bowel disease and Behcet's disease, or merely autoimmune phenomena associated with inflammatory bowel disease. Unusual colonoscopic lesions noted in our patient and other features enumerated in the text suggested to us that at least some of these cases represented primary Behcet's disease involving the colon.