In vivo evaluation of a vibration analysis technique for the per-operative monitoring of the fixation of hip prostheses

<p>Abstract</p> <p>Background</p> <p>The per-operative assessment of primary stem stability may help to improve the performance of total hip replacement. Vibration analysis methods have been successfully used to assess dental implant stability, to monitor fracture healing and to measure bone mechanical properties. The objective of the present study was to evaluate in vivo a vibration analysis-based endpoint criterion for the insertion of the stem by successive surgeon-controlled hammer blows.</p> <p>Methods</p> <p>A protocol using a vibration analysis technique for the characterisation of the primary bone-prosthesis stability was tested in 83 patients receiving a custom-made, intra-operatively manufactured stem prosthesis. Two groups were studied: one (n = 30) with non cemented and one (n = 53) with partially cemented stem fixation. Frequency response functions of the stem-femur system corresponding to successive insertion stages were compared.</p> <p>Results</p> <p>The correlation coefficient between the last two frequency response function curves was above 0.99 in 86.7% of the non cemented cases. Lower values of the final correlation coefficient and deviations in the frequency response pattern were associated with instability or impending bone fracture. In the cases with a partially cemented stem an important difference in frequency response function between the final stage of non cemented trial insertion and the final cemented stage was found in 84.9% of the cases. Furthermore, the frequency response function varied with the degree of cement curing.</p> <p>Conclusion</p> <p>The frequency response function change provides reliable information regarding the stability evolution of the stem-femur system during the insertion. The protocol described in this paper can be used to accurately detect the insertion end point and to reduce the risk for intra-operative fracture.</p

HCMV Targets the Metabolic Stress Response through Activation of AMPK Whose Activity Is Important for Viral Replication

Human Cytomegalovirus (HCMV) infection induces several metabolic activities that have been found to be important for viral replication. The cellular AMP-activated protein kinase (AMPK) is a metabolic stress response kinase that regulates both energy-producing catabolic processes and energy-consuming anabolic processes. Here we explore the role AMPK plays in generating an environment conducive to HCMV replication. We find that HCMV infection induces AMPK activity, resulting in the phosphorylation and increased abundance of several targets downstream of activated AMPK. Pharmacological and RNA-based inhibition of AMPK blocked the glycolytic activation induced by HCMV-infection, but had little impact on the glycolytic pathway of uninfected cells. Furthermore, inhibition of AMPK severely attenuated HCMV replication suggesting that AMPK is an important cellular factor for HCMV replication. Inhibition of AMPK attenuated early and late gene expression as well as viral DNA synthesis, but had no detectable impact on immediate-early gene expression, suggesting that AMPK activity is important at the immediate early to early transition of viral gene expression. Lastly, we find that inhibition of the Ca2+-calmodulin-dependent kinase kinase (CaMKK), a kinase known to activate AMPK, blocks HCMV-mediated AMPK activation. The combined data suggest a model in which HCMV activates AMPK through CaMKK, and depends on their activation for high titer replication, likely through induction of a metabolic environment conducive to viral replication

Risk Factors for and Clinical Outcome of Congenital Cytomegalovirus Infection in a Peri-Urban West-African Birth Cohort

BACKGROUND: Congenital cytomegalovirus (CMV) infection is the most prevalent congenital infection worldwide. Epidemiology and clinical outcomes are known to vary with socio-economic background, but few data are available from developing countries, where the overall burden of infectious diseases is frequently high. METHODOLOGY/PRINCIPAL FINDINGS: As part of an ongoing birth cohort study in The Gambia among term infants, urine samples were collected at birth and tested by PCR for the presence of CMV DNA. Risk factors for transmission and clinical outcome were assessed, including placental malaria infection. Babies were followed up at home monthly for morbidity and anthropometry, and at one year of age a clinical evaluation was performed. The prevalence of congenital CMV infection was 5.4% (40/741). A higher prevalence of hepatomegaly was the only significant clinical difference at birth. Congenitally infected children were more often first born babies (adjusted odds ratio (OR) 5.3, 95% confidence interval (CI) 2.0-13.7), more frequently born in crowded compounds (adjusted OR 2.9, 95%CI 1.0-8.3) and active placental malaria was more prevalent (adjusted OR 2.9, 95%CI 1.0-8.4). These associations were corrected for maternal age, bed net use and season of birth. During the first year of follow up, mothers of congenitally infected children reported more health complaints for their child. CONCLUSIONS/SIGNIFICANCE: In this study, the prevalence of congenital CMV among healthy neonates was much higher than previously reported in industrialised countries, and was associated with active placental malaria infection. There were no obvious clinical implications during the first year of life. The effect of early life CMV on the developing infant in the Gambia could be mitigated by environmental factors, such as the high burden of other infections.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Bovine Leukemia Virus (BLV) - A structural model based on chemical crosslinking studies

Nearest neighbor relationships between lipid and protein as well as between high-molecular-weight viral RNA and protein were investigated in bovine leukemia virus (BLV) particles using chemical crosslinking reagents. Separation of dimethyl suberimidate (DMS) induced lipid-protein complexes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the phosphoprotein pp 15 is linked to the lipid bilayer of the virus. By use of diepoxybutan (DEB) as crosslinking reagent p 12 and again pp 15 were found to be linked to the viral RNA. Based on these results and our previous data describing the spatial relationships of major structural proteins within BLV particles, a structural model of BLV is proposed. © 1984.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Replicative and cytopathic potential of HTLV-III/LAV with sor gene deletions.

The genome of the human T-lymphotropic virus type III (HTLV-III/LAV) has the potential to encode at least three polypeptides in addition to those encoded by the gag, pol, and env genes. In this study, the product of the sor (short open reading frame) region, which overlaps the 3' end of the pol gene, was found to be a protein with a molecular weight of 23,000. An assay was developed for testing the ability of cloned HTLV-III proviruses to produce viruses cytopathic for T4+ lymphocytes. In the cell line used, C8166, neither the HTLV-III sor gene product nor the complete 3'-orf gene product were necessary for the replication or cytopathic effects of the HTLV-III.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Trans activation of the bovine leukemia virus long terminal repeat in BLV-infected cells.

The transcription initiation signals for retroviruses lie within the long terminal repeat (LTR) sequences that flank the integrated provirus. This study shows that factors present in cells infected with bovine leukemia virus (BLV) mediate transcriptional trans activation of the BLV LTR. This phenomenon is similar to that reported for the human T-cell leukemia virus LTR and establishes both structural and functional criteria for inclusion of BLV and human T-cell leukemia viruses in the same family of transforming retroviruses.SCOPUS: ar.jinfo:eu-repo/semantics/publishe