Level III, Retrospective Comparative Study.

Contributions of the alternative sigma factorB to Listeria monocytogenes infection were investigated using strains bearing null mutations in sigB, prfA, or inlA or in selected inlA or prfA promoter regions. The ⌬P4 inlA strain, which has a deletion in the B -dependent P4 inlA promoter, and the ⌬sigB strain had significantly reduced invasion efficiencies relative to that of the wild-type strain in the Caco-2 human colorectal epithelial cell line, while the invasion efficiency of a strain bearing a deletion in the partially B dependent P2 prfA promoter region did not differ from that of the wild type. The virulence of the ⌬sigB and ⌬P4 inlA strains was attenuated in intragastrically inoculated guinea pigs, with the ⌬sigB strain showing greater attenuation, while the virulence capacity of the ⌬P2 prfA strain was similar to that of the wild-type strain, suggesting that attenuation of virulence due to the ⌬sigB mutation does not result from loss of B -dependent prfA transcription. Our results show that B -dependent activation of inlA is important for cell invasion and gastrointestinal infection and suggest that B -regulated genes in addition to inlA appear to contribute to gastrointestinal infection. Interestingly, the virulence of the ⌬sigB strain was not attenuated in intravenously infected guinea pigs. We conclude that (i) L. monocytogenes B plays a critical role in invasion of human host cells, (ii) B -mediated contributions to invasion are, in part, due to direct effects on inlA transcription but not on prfA transcription, and (iii) B plays a critical role during the gastrointestinal stage of listeriosis in the guinea pig but is not important for systemic spread of the organism. Listeriosis results from consumption of food contaminated withListeria monocytogenes (40). To cause a human food-borne infection, L. monocytogenes must survive conditions encountered in the oral cavity, the stomach, and the intestine, which include exposure to lysozyme activity, gastric acidity, and bile salts (16). L. monocytogenes can invade the epithelial cells of the small intestine, then spread into mesenteric lymph nodes and disseminate systemically in the blood. Listeriosis is a relatively rare disease among healthy individuals, at least in part because the majority of L. monocytogenes organisms that enter the bloodstream are captured by the Kupffer cells in the liver and are killed by neutrophils (18). Listeriosis occurs predominantly among the immunocompromised, the elderly, and pregnant women and their fetuses (33). In susceptible individuals, L. monocytogenes can cross the bloodbrain barrier to cause central nervous system infections and the placental barrier to cause fetal infections (48). L. monocytogenes cells that escape the antimicrobial activity of the neutrophils can enter hepatocytes or endothelial cells or can be disseminated further to other tissues. Following invasion of nonphagocytic host cells, L. monocytogenes can escape from the host cell vacuole, then replicate intracellularly and spread from cell to cell (6,15...

BackgroundCompartment syndrome is an elevation of intracompartmental pressure to a level that impairs circulation. While the most common etiology is trauma, other less common etiologies such as burns, emboli, and iatrogenic injuries can be equally troublesome and challenging to diagnose. The sequelae of a delayed diagnosis of compartment syndrome may be devastating. All care providers must understand the etiologies, high-risk situation, and the urgency of intervention.Questions/PurposesThis study was conducted to perform a comprehensive review of compartment syndrome discussing etiologies, risk stratification, clinical progression, noninvasive and invasive monitoring, documentation, medical-legal implication, and our step-by-step approach to compartment syndrome prevention, detection, and early intervention.MethodsA literature search was performed using the PubMed Database and the following search terms: “Compartment syndrome AND Extremity,” “Compartment syndrome AND Gluteal,” and Compartment syndrome AND Paraspinal.” A total of 2,068 articles were identified. Filters allowed for the exclusion of studies not printed in English (359) and those focusing on exertional compartment syndrome (84), leaving a total of 1,625 articles available for review.ResultsThe literature provides details regarding the etiologies, risk stratification, clinical progression, noninvasive and invasive monitoring, documentation, medical-legal implication, and our step-by-step approach to compartment syndrome prevention, detection, and early intervention. The development and progression of compartment syndrome is multifactorial, and as complexity of care increases, the opportunity for the syndrome to be missed is increased. Recent changes in the structure of in-hospital medical care including resident work hour restrictions and the incorporation of midlevel providers have increased the frequency of “signouts” or “patient handoffs” which present opportunities for the syndrome to be mismanaged.ConclusionThe changing dynamics of the health care team have prompted the need for a more explicit algorithm for managing patients at risk for compartment syndrome to ensure appropriate conveyance of information among team members.Electronic supplementary materialThe online version of this article (doi:10.1007/s11420-014-9386-8) contains supplementary material, which is available to authorized users.

The oxidation state of methionine and cysteine in normal and cataractous lenses is reported. In young lenses no oxidation was detected in any protein fraction examined. Only the intrinsic membrane fraction and membrane-related components showed evidence of oxidation in old (60-65 years of age) normal lenses. However, in a similar age group, with the development of cataract, progressive, dramatic changes were observed. With severe cataracts, 60% or more of the methionine in membrane-associated components was found in the methionine sulfoxide form, and met ionine sulfone was observed in one case. Most of the cysteine was found oxidized to either the disulfide form or putative cysteic acid. Mixed disulfides with glutathione were observed. Oxidative changes in soluble components as illustrated by a-crystallin occurred more gradually. The data clearly support the viewpoint that extensive oxidation of lens proteins occurs with cataract and that it begins at the lens fiber membrane.The question arises as to whether oxidation of the sulfur found in cataractous lens homogenates is random or, conversely, whether the oxidation progresses in a particular order from specific regions and polypeptides of the tissue.In the study reported here, methionine and cysteine oxidation in selected fractions of lens tissue homogenates was measured. The data suggest that, in the aging normal lens, oxidation of cysteine and methionine occurs only in the intrinsic membrane fraction and to some extent in the high molecular weight membrane-associated fractions. In the severe cataractous lens, the oxidation occurs not only in the intrinsic membrane fraction but in all fractions examined. Furthermore, higher sulfur oxidation states are observed in membrane-related fractions in cataract lenses.The formation of certain types of cataract appears to be associated with the generation of high molecular weight aggregates which act as scatter points of light (1, 2). Comparison of the quantity and polypeptide compositions of the water-soluble and -insoluble material of normal and cataractous lenses of the same age shows that the amount of water-insoluble material and high molecular weight aggregates increases at the expense of water-soluble protein (3). High molecular weight disulfidelinked aggregates, unique to cataract, can be isolated (4). Partial characterization of these aggregates indicates the presence of a 43,000-dalton polypeptide that is an extrinsic membrane component in the normal lens (5), polypeptides in the 20,000-dalton range including a major component related to y-crystallin,* and a 9600-dalton polypeptide fraction (5). Also present in this high molecular weight disulfide-linked aggregate is a diffuse, poorly defined species that contains lipid (unpublished data). This component, present in the normal lens as well, may be membrane associated. The water-insoluble material of both normal and cataractous lenses may also contain noncovalently linked aggregates (6).Many of the changes associated with cataract may be caused by oxida...

The effects of environmental stress exposure on Listeria monocytogenes growth and virulence-associated characteristics were investigated. Specifically, we measured the effects of temperature (7 or 37°C), pH (5.5 or 7.4), the presence of salt and organic acids (375 mM NaCl, 8.45 mM sodium diacetate [SD], 275 mM sodium lactate [SL], or a combination of NaCl, SD, and SL), and deletion of sigB, which encodes a key stress response regulator, on the ability of L. monocytogenes to grow, invade Caco-2 cells, and survive exposure to synthetic gastric fluid (pH 2.5 or 4.5). Our results indicate that (i) L. monocytogenes log-phase generation times and maximum cell numbers are not dependent on the alternative sigma factor B in the presence of NaCl and organic acids at concentrations typically found in foods; (ii) growth inhibition of L. monocytogenes through the addition of organic acids is pH dependent; (iii) the ability of L. monocytogenes to invade Caco-2 cells is affected by growth phase, temperature, and the presence of salt and organic acids, with the highest relative invasion capabilities observed for cells grown with SL or NaCl at 37°C and pH 7.4; (iv) growth of L. monocytogenes in the presence of NaCl, SD, or SL reduces its ability to survive exposure to gastric fluid; and (v) exposure of L. monocytogenes to gastric fluid reduces the enhanced invasiveness caused by growth in the presence of NaCl or SL. These findings suggest that virulence-associated characteristics that determine the L. monocytogenes infectious dose are likely to be affected by food-specific properties (e.g., pH or the presence of salt or organic acid).