Loss of lipopolysaccharide receptor CD14 from the surface of human macrophage-like cells mediated by Porphyromonas gingivalis outer membrane vesicles

Porphyromonas gingivalis, the major etiologic agent of chronic periodontitis, produces a broad spectrum of virulence factors, including outer membrane vesicles. In this study, we investigated the capacity of P. gingivalis vesicles to promote the shedding or cleavage of the lipopolysaccharide (LPS) receptor CD14 from the surface of human U937 macrophage-like cells. SDS-PAGE/Western immunoblotting analysis of gingival crevicular fluid samples from patients affected by moderate or advanced periodontitis revealed the presence of soluble CD14 and CD14 fragments, thus supporting the hypothesis of an in vivo shedding and cleavage of CD14 receptors. Flow cytometry analysis of macrophage-like cells treated with a vesicle-containing culture supernatant of P. gingivalis showed a significant decrease in the binding of anti-human CD14 to the cell surface. However, no accumulation of soluble CD14 or immunoreactive CD14 fragments in the assay supernatant could be demonstrated by ELISA. Treatment of macrophage-like cells with various concentrations of P. gingivalis vesicles substantially suppressed TNF-alpha production triggered by Escherichia coli LPS. This suppressive effect was much less important using heat-treated vesicles or in the presence of leupeptin, a gingipain inhibitor, during the treatment. Recombinant human CD14 receptors were found to be susceptible to proteolytic degradation by P. gingivalis vesicles. A purified Arg-gingipain preparation produced much more degradation than a Lys-gingipain preparation. This study provides evidence that P. gingivalis outer membrane vesicles contribute to the loss of membrane-bound CD14 receptors and that gingipains degrade this LPS receptor. Such a phenomenon, which results in an hyporesponsiveness of macrophages to LPS stimulation, may contribute to an increased capacity of P. gingivalis, and other periodontopathogens, to evade the host immune system mechanisms.     

Effects of acculturation on prenatal anxiety among Latina women

Anxiety in pregnancy has been associated with adverse birth outcomes. Relatively few studies have investigated how acculturation affects mental health in pregnancy among Latinas. The goal of this study was to determine if acculturation was associated with anxiety over the course of pregnancy in a sample of predominantly Puerto Rican women. Women were recruited in pregnancy for participation in Proyecto Buena Salud, a prospective cohort study of Latina women (n?=?1412). Acculturation was measured via the Psychological Acculturation Scale (PAS), language preference and generation in the USA. Anxiety was measured using the State-Trait Anxiety Instrument. Linear and logistic multivariable regressions were used to investigate associations. After adjustment, women with bicultural identification had significantly lower trait anxiety scores in early pregnancy (β?=??3.62, SE?=?1.1, p?<?0.001) than low acculturated women. Women with higher levels of acculturation as indicated by English-language preference (β?=?1.41, SE?=?0.7, p?=?0.04) and second or third generation in the USA had significantly higher trait anxiety scores in early pregnancy (β?=?1.83, SE?=?0.6, p?<?0.01). Bicultural psychological acculturation was associated with lower trait anxiety in early pregnancy, while English-language preference and higher generation in the USA were associated with higher trait anxiety in early pregnancy.     

Centrosomes in the DNA damage response—the hub outside the centre

Here, we review how DNA damage affects the centrosome and how centrosomes communicate with the DNA damage response (DDR) apparatus. We discuss how several proteins of the DDR are found at centrosomes, including the ATM, ATR, CHK1 and CHK2 kinases, the BRCA1 ubiquitin ligase complex and several members of the poly(ADP-ribose) polymerase family. Stereotypical centrosome organisation, in which two centriole barrels are orthogonally arranged in a roughly toroidal pericentriolar material (PCM), is strongly affected by exposure to DNA-damaging agents. We describe the genetic dependencies and mechanisms for how the centrioles lose their close association, and the PCM both expands and distorts after DNA damage. Another consequence of genotoxic stress is that centrosomes undergo duplication outside the normal cell cycle stage, meaning that centrosome amplification is commonly seen after DNA damage. We discuss several potential mechanisms for how centrosome numbers become dysregulated after DNA damage and explore the links between the DDR and the PLK1- and separase-dependent mechanisms that drive centriole separation and reduplication. We also describe how centrosome components, such as centrin2, are directly involved in responding to DNA damage. This review outlines current questions on the involvement of centrosomes in the DDR.     

Lymph node biopsy analysis reveals an altered immunoregulatory balance already during the at‐risk phase of autoantibody positive rheumatoid arthritis

The balance between proinflammatory and regulatory CD4⁺ T cells is tightly controlled in lymphoid organs. In autoimmune diseases this balance is altered in the periphery and target tissue of patients. However, not much is known about the balance initiated in lymphoid organs during the development of disease. Since systemic autoimmunity is present years before the clinical manifestations of rheumatoid arthritis (RA), it is possible to study the immunoregulatory balance during the earliest (preclinical) phases of disease. Here, we report for the first time the frequency and phenotype of proinflammatory and regulatory CD4⁺ T cells in lymph node biopsies obtained from autoantibody positive individuals at risk for developing RA, patients with established disease and healthy controls. The frequency of proinflammatory LN Th1 cells was increased in RA patients compared with HCs, while the frequency of regulatory T cells was lower in LN biopsies of RA‐risk individuals. Upon in vitro stimulation LN CD4⁺ T cells produced lower levels of proinflammatory cytokines, IFN‐γ and IL‐17A, in both RA‐risk individuals and early RA patients. This study shows that already during the earliest phases of systemic autoimmunity the immunoregulatory balance between proinflammatory and regulatory CD4⁺ T cells is altered in LN tissue.     

Functionalized Polymers from α‐Hydroxyalkylated N‐Vinylcaprolactam

Hydroxyalkylation of N‐vinylcaprolactam (NVCL) in α‐position via ring‐opening reaction of propylene oxide and ε‐caprolactone, respectively, yields in precursors for multifunctional NVCL derivatives. Homo‐ and copolymers of hydroxyfunctionalized NVCL derivatives, synthesized by free radical mechanism, are further investigated regarding their thermoresponsive behavior. Esterification of hydroxypropylated NVCL derivative with methacrylic anhydride is carried out yielding a versatile bifunctional cross‐linker. Networks are obtained either via free radical polymerization of the cross‐linker or anionic polymerization of only the methacrylic function and subsequent polymer analogous cross‐linking of the vinylic side groups. The rheological behavior during and after curing is investigated by oscillatory rheology. Furthermore, N‐vinylcaprolactam anion is used as an initiator for the anionic ring‐opening polymerization of ε‐caprolactone. Copolymerization of poly(ε‐caprolactone) macromonomer with NVCL yields graft copolymers. A polymerizable thermotropic liquid crystalline (LC) derivative is prepared by coupling cholesteryl chloroformate to NVCL. The thermal behavior of LC derivative is investigated by differential scanning calorimetry and polarized light microscopy.

     

Tissue temperature oscillations in an isolated pig kidney during surface heating

In the present study, an isolated pig kidney was used to study tissue temperature oscillations due to vascular thermoregulation, frequently observed during hyperthermia treatments. The kidney was perfused with the distilled water pumped through the renal artery to simulate blood flow. When the local perfusion rate was increased with a time delay, temperature oscillations were observed in the kidney as its surface temperature raised linearly with time in a water bath. The magnitude of tissue temperature decreased as the flow rate increased during the surface heating. A 3D transient model was developed to predict the temperature oscillations, which was validated by the measurements. Using the model, relationships of the changes in perfusion rate and heating rate with temperature oscillations were investigated. It was found that the heating rate, and the magnitude and time delay of the flow response to the temperature elevation, each significantly affected tissue temperature oscillations. The magnitude of oscillation was primarily determined by the spatial gradient of temperature, while the oscillation type depended on the change of flow rate and the time delay. In conclusion, to accurately predict and control the tissue temperature distribution during hyperthermia treatment, understanding of the local perfusion change with respect to tissue temperature is essential. © 2002 Biomedical Engineering Society. PAC2002: 8719Pp, 8754Br, 8719Uv, 8710+e     

Plasma HIV-1 RNA viral load rebound among people who inject drugs receiving antiretroviral therapy (ART) in a Canadian setting: an ethno-epidemiological study

Background

People who inject drugs (PWID) living with HIV often experience sub-optimal antiretroviral therapy (ART) treatment outcomes, including HIV plasma viral load (PVL) rebound. While previous studies have identified risk factors for PVL rebound among PWID, no study has examined the perspectives of PWID who have experienced PVL rebound episodes. We conducted an ethno-epidemiological study to investigate the circumstances surrounding the emergence of rebound episodes among PWID in Vancouver, BC, Canada.

Methods

Comprehensive clinical records linked to a community-based prospective observational cohort of HIV-positive drug users were used to identify PWID who had recently experienced viral rebound. In-depth qualitative interviews with 16 male and 11 female participants explored participant perspectives regarding the emergence of viral rebound. A timeline depicting each participant’s HIV viral load and adherence to ART was used to elicit discussion of circumstances surrounding viral rebound.

Findings

Viral rebound episodes were shaped by interplay between various individual, social, and environmental factors that disrupted routines facilitating adherence. Structural-environmental influences resulting in non-adherence included housing transitions, changes in drug use patterns and intense drug scene involvement, and inadequate care for co-morbid health conditions. Social-environmental influences on ART adherence included poor interactions between care providers and patients producing non-adherence, and understandings of HIV treatment that fostered intentional treatment discontinuation.

Conclusions

This study describes key pathways which led to rebound episodes among PWID receiving ART and illustrates how environmental forces may increase vulnerability for non-adherence leading to treatment failure. Our findings have potential to help inform interventions and supports that address social-structural forces that foster non-adherence among PWID.

     

Using the Health Belief Model to Examine the Link between HPV Knowledge and Self-Efficacy for Preventive Behaviors of Male Students at a Two-Year College in New York City

The human papillomavirus (HPV) is one of the most common and easily transmitted sexually transmitted infections in the United States; infected individuals are frequently unaware that they are carriers, and transmission occurs unknowingly. Infection can lead to genital warts or cervical, penile, anal, or oral cancer. The object of this study was to examine the link between HPV knowledge and self-efficacy for preventive behaviors among college students as well as HPV vaccine acceptability. A cross-sectional survey of students at a two-year college in New York City was conducted electronically. The current study focuses on male students (N = 120). We found that HPV knowledge was low among this sample, but that self-efficacy and vaccine acceptability were high. Self-efficacy and perceived susceptibility to HPV predicted vaccine acceptability, but not condom use. The challenge for health care practitioners and health educators is to provide focused, comprehensive education about HPV without causing undue fear.