Oral nutrition or water loading before hip replacement surgery; a randomized clinical trial

Background

Hand hygiene is considered as an important means of infection control. We explored whether guided hand hygiene together with transmission-limiting behaviour reduces infection episodes and lost days of work in a common work environment in an open cluster-randomized 3-arm intervention trial.

Methods

A total of 21 clusters (683 persons) were randomized to implement hand hygiene with soap and water (257 persons), with alcohol-based hand rub (202 persons), or to serve as a control (224 persons). Participants in both intervention arms also received standardized instructions on how to limit the transmission of infections. The intervention period (16 months) included the emergence of the 2009 influenza pandemic and the subsequent national hand hygiene campaign influencing also the control arm.

Results

In the total follow-up period there was a 6.7% reduction of infection episodes in the soap-and water arm (p = 0.04). Before the onset of the anti-pandemic campaign, a statistically significant (p = 0.002) difference in the mean occurrence of infection episodes was observed between the control (6.0 per year) and the soap-and-water arm (5.0 per year) but not between the control and the alcohol-rub arm (5.6 per year). Neither intervention had a decreasing effect on absence from work.

Conclusions

We conclude that intensified hand hygiene using water and soap together with behavioural recommendations can reduce the occurrence of self-reported acute illnesses in common work environment. Surprisingly, the occurrence of reported sick leaves also increased in the soap-and water-arm.

Trial Registration

ClinicalTrials.gov: NCT00981877

Source of funding

The Finnish Work Environment Fund and the National Institute for Health and Welfare.     

Displacement of the occluding loop by the parasite protein, chagasin, results in efficient inhibition of human cathepsin B

Cathepsin B is a papain-like cysteine protease showing both endo- and exopeptidase activity, the latter due to a unique occluding loop that restricts access to the active site cleft. To clarify the mode by which natural protein inhibitors manage to overcome this obstacle, we have analyzed the structure and function of cathepsin B in complexes with the Trypanosoma cruzi inhibitor, chagasin. Kinetic analysis revealed that substitution of His-110e, which anchors the loop in occluding position, results in 3-fold increased chagasin affinity (Ki for H110A cathepsin B, 0.35 nm) due to an improved association rate (kon, 5 x 10(5) m(-1)s(-1)). The structure of chagasin in complex with cathepsin B was solved in two crystal forms (1.8 and 2.67 angstroms resolution), demonstrating that the occluding loop is displaced to allow chagasin binding with its three loops, L4, L2, and L6, spanning the entire active site cleft. The occluding loop is differently displaced in the two structures, indicating a large range of movement and adoption of conformations forced by the inhibitor. The area of contact is slightly larger than in chagasin complexes with the endopeptidase, cathepsin L. However, residues important for high affinity to both enzymes are mainly found in the outer loops L4 and L6 of chagasin. The chagasin-cathepsin B complex provides a structural framework for modeling and design of inhibitors for cruzipain, the parasite cysteine protease and a virulence factor in Chagas disease.     

IFN-gamma production dominates the early human natural killer cell response to Coxsackievirus infection

Coxsackieviruses (CV) are important human pathogens that have been implicated in the pathogenesis of several diseases, including myocarditis and pancreatitis. How the human immune system recognizes and controls CV infections is not well understood. Studies in mice suggest that natural killer (NK) cells play a critical role in viral clearance and host survival, but the mechanism(s) by which human NK cells may contribute to the host anti-CV defence has not been investigated. Here we show that CVB3 infection markedly reduces HLA class I cell surface expression but does not increase the expression of the activating NK cell receptor ligands MICA/B and ULBP1-3 on human cells. We also demonstrate that the lowered target cell HLA class I surface expression does not correlate with an increased susceptibility to NK cell-mediated killing. However, NK cells responded with a robust production of interferon γ (IFN-γ) when peripheral blood mononuclear cells were cocultured with infected cells. In summary, this study shows that CVB3 interferes with the expression of NK cell receptor ligands on infected cells and indicates that IFN-γ production, rather than cytotoxicity, marks the early human NK cell response to CVB3 infection.     

NK cell triggering by the human costimulatory molecules CD80 and CD86.

NK cell-mediated effector functions are regulated by a delicate balance between positive and negative signals. Receptors transmitting negative signals upon engagement with target cell MHC class I molecules have been characterized in detail in recent years. In contrast, less information is available about receptor-ligand interactions involved in the transmission of positive or "triggering" signals to NK cells. Recently, it has been described that murine NK cells are triggered by the costimulatory molecules CD80, CD86, and CD40. Using NK cell lines derived from PBMC as effectors, we demonstrate that the human CD80 and CD86 gene products can function as triggering molecules for NK cell-mediated cytotoxicity. Expression of human CD80 or CD86 molecules in murine B16.F1 melanoma cells rendered these significantly more susceptible to lysis by human NK cell lines. Blocking of the transfected gene products with specific mAb reduced lysis levels to that of nontransfected control cell lines. Triggering of human NK cells by CD80 and CD86 appeared to be independent of CD28 and CTLA-4, at least as determined by the reagents used in the present study, because the expression of these molecules could not be detected on the NK cell lines by either flow cytometry or in redirected lysis assays. Thus, human NK cells may use receptors other than CD28 and CTLA-4 in their interactions with CD80 and CD86 molecules. Alternatively, interactions may involve variants of CD28 (and possibly CTLA-4) that are not recognized by certain anti-CD28 mAb.     

The crystal structure of the major cat allergen Fel d 1, a member of the secretoglobin family

The domestic cat (Felis domesticus) is one of the most important causes of allergic asthma worldwide. The dominating cat allergen, Fel d 1, is composed of two heterodimers. Recently, it has been shown that recombinant Fel d 1, consisting of chain 2 and chain 1 fused together without additional linker, has immunological properties indistinguishable from the natural heterodimeric protein. Herein, we report the crystal structure of recombinant monomeric Fel d 1 at 1.85-A resolution, determined by multi-wavelength anomalous diffraction using selenomethionine substituted protein. Fel d 1 is an all-helical protein and consists of eight helices. The two halves of the recombinant Fel d 1 molecule, corresponding to the wild-type Fel d 1 chains, are very similar in three-dimensional structure, despite the lack of significant sequence identity. The structure of the Fel d 1 presents a striking similarity to that of uteroglobin, a steroid-inducible cytokine-like molecule with anti-inflammatory and immunomodulatory properties. An internal, asymmetric cavity is formed in the Fel d 1 that could bind an endogenous ligand. The distribution of residues lining this cavity suggests that such a ligand must be amphipathic. The structure of Fel d 1 displays the localization of three previously defined Fel d 1 IgE epitopes on the surface of the protein. The three-dimensional structure provides a framework for rational design of hypoallergenic mutants aimed for treatment of cat allergy.     

Emergence of CD8+ T cells expressing NK cell receptors in influenza A virus-infected mice

Both innate and adaptive immune responses play an important role in the recovery of the host from viral infections. In the present report, a subset of cells coexpressing CD8 and NKR-P1C (NK1.1) was found in the lungs of mice infected with influenza A virus. These cells were detected at low numbers in the lungs of uninfected mice, but represented up to 10% of the total CD8(+) T cell population at day 10 postinfection. Almost all of the CD8(+)NK1.1(+) cells were CD8alphabeta(+)CD3(+)TCRalphabeta(+) and a proportion of these cells also expressed the NK cell-associated Ly49 receptors. Interestingly, up to 30% of these cells were virus-specific T cells as determined by MHC class I tetramer staining and by intracellular staining of IFN-gamma after viral peptide stimulation. Moreover, these cells were distinct from conventional NKT cells as they were also found at increased numbers in influenza-infected CD1(-/-) mice. These results demonstrate that a significant proportion of CD8(+) T cells acquire NK1.1 and other NK cell-associated molecules, and suggests that these receptors may possibly regulate CD8(+) T cell effector functions during viral infection.     

Increased Soluble Urokinase-Type Plasminogen Activator Receptor (suPAR) Levels in Plasma of Suicide Attempters

The soluble form of the urokinase receptor, suPAR, has been suggested as a novel biomarker of low-grade inflammation. Activation of the immune system has been proposed to contribute to the development of depression and suicidal behavior. In order to identify depressed and suicidal individuals who could benefit from an anti-inflammatory treatment, a reliable biomarker of low-grade inflammation is vital. This study evaluates plasma suPAR levels as a biomarker of low-grade inflammation in patients with major depressive disorder and in patients who recently attempted suicide. The plasma suPAR and an established biomarker, C reactive protein (CRP) of suicide attempters (n = 54), depressed patients (n = 19) and healthy controls (n = 19) was analyzed with enzyme-linked immunosorbent assays. The biomarker attributes of sensitivity and sensibility were evaluated using ROC curve analysis. Both the depressed patients and suicide attempters had increased plasma suPAR. The levels of suPAR discriminated better between controls and suicide attempters than did CRP. In the future, plasma suPAR might be a superior prognosticator regarding outcome of treatment applying conventional antidepressants in conjunction with anti-inflammatory drugs.     

Induction of a metabolic switch in insect cells by substrate-limited fed batch cultures

Insect cell metabolism was studied in substrate-limited fed batch cultures of Spodoptera frugiperda (Sf-9) cells. Results from a glucose-limited culture, a glutamine-limited culture, a culture limited in both glucose and glutamine and a batch culture were compared. A stringent relation between glucose excess and alanine formation was found. In contrast, glucose limitation induced ammonium formation, while, at the same time, alanine formation was completely suppressed. Simultaneous glucose and glutamine limitation suppressed both alanine and ammonium formation. Although the metabolism was influenced by substrate limitation, the specific growth rate was similar in all cultures. Alanine formation must involve incorporation of free ammonium, if ammonium formation is mediated by glutaminase and glutamate dehydrogenase, as our data suggest. On the basis of the results, two possible pathways for the formation of alanine in the intermediary metabolism in insect cells are suggested. The cellular yield on glucose was increased 6.6 times during glucose limitation, independently of the cellular yield on glutamine, which was increased 50–100 times during glutamine limitation. The results indicate that alanine overflow metabolism is energetically wasteful and that glutamine is a dispensable amino acid for cultured Sf-9 cells. Preliminary data confirm that glutamine can be synthesised by the cells themselves in amounts sufficient to support growth.