Experimental and Analytical Performance Evaluation of Short Circular Hydrodynamic Journal Bearings Used in Rotary Blood Pumps

Rotary blood pumps (RBPs) have demonstrated considerable promise while treating heart failure patients, such that they are being placed at an earlier stage of the disease. These devices may therefore be required to operate for prolonged durations which yields the need for RBPs exhibiting high durability, reliability, and blood compatibility. Noncontacting bearings, utilizing magnetic and/or hydrodynamic suspension techniques, appear to provide a suitable solution to these challenges. Hydrodynamic suspension has the advantage that it does not need feedback control systems. Among various hydrodynamic bearing types, the circular journal bearing has the particular benefit of easy manufacturing. This study presents methods to evaluate the performance of short (length to diameter ratio <1) circular hydrodynamic journal bearings (HJBs) for RBPs. Analytical calculations with specific boundary conditions are presented to predict the rotor's eccentricity under equilibrium states and thus the related performance parameters such as load capacity, power loss, and shear rates. These results and boundary conditions were confirmed experimentally in a specially designed test set‐up. The bearing performance was found to correlate to analytical solutions using the full Sommerfeld boundary condition instead of the half Sommerfeld condition conventionally used for such applications. Geometrical and operational parameter variations showed that HJB designs with a short Sommerfeld Number S_S >0.02 can provide sufficient fluid film thicknesses and low shear rates. The measurements were further used to evaluate the bearings' stability. The estimation of the stability threshold drawn in relation to a modified stability index and the equilibrium eccentricity of the rotor allows the prediction of stability for short circular HJB designs under full Sommerfeld condition.     

Salvage of a free radial forearm flap by creation of an arteriovenous fistula at the distal arterial pedicle

Interdisciplinary approaches with infrainguinal bypass grafts and free flaps between the plastic and vascular surgery may well offer an opportunity for diabetic patients with peripheral vascular disease to salvage their critically affected limbs. A free flap transfer combined with an autologous vein graft can cover large tissue defects and simultaneously improve distal perfusion even in patients with arterial occlusive disease. We are presenting a case of bypass‐free radial forearm flap used to cover a foot defect in an old diabetic patient with peripheral arterial disease. The flap perfusion deteriorated significantly during the early postoperative period. The patient was brought back to the operating room with acute thrombosis of the popliteal‐radial venous graft and the arterial pedicle of the flap. The flap was salvaged by thrombectomy and creation of an additional arteriovenous fistula at the distal arterial pedicle. The procedure improved the flap perfusion and decreased the high internal resistance that was noticed in the flap when trying to flush the radial artery during the revision surgery and was evident by continuous wave ‐Doppler sonography. The successful salvage of the flap in the presented case and the convenient long‐term follow up suggest that this technique may be safe and helpful as a last effort to salvage a bypass‐free flap with a suspected high internal resistance. © 2013 Wiley Periodicals, Inc. Microsurgery 33:391–395, 2013.     

Lifestyle Risk Factors Associated with Arm Swelling Among Women with Breast Cancer

Background

Breast cancer-related lymphedema (BCRL) is a feared complication for breast cancer patients who have undergone axillary surgery. Although clinical risk factors for BCRL are defined, data are sparse regarding common exposures that might induce incident arm swelling. The goal of this study was to quantify the association between common exposures thought to be potential risk factors and the occurrence of incident arm swelling among breast cancer survivors with or at risk for BCRL.

Methods

This is a prospective subanalysis of the Physical Activity and Lymphedema (PAL) trial, a randomized controlled trial of 295 breast cancer survivors. Participants reported their exposure to 30 different potential risk factors at 3 month intervals for 1 year. Incident arm swelling was defined as a ≥5 % increase in interlimb water volume difference between two consecutive time points.

Results

Twenty-seven participants (9 %) experienced incident arm swelling and 268 patients (91 %) did not. Sauna use was the only exposure that was significantly predictive of incident arm swelling (p = 0.05). Nonwhite and nonblack participants had a significantly increased risk for experiencing incident arm swelling (p = 0.005 for both comparisons).

Conclusions

In our patient cohort, many common exposures that have been reported to be risk factors did not prove to have a significant predictive relationship for incident arm swelling. This study supports the recommendation that breast cancer patients who have had axillary surgery should avoid sauna use. The results do not confirm the need for other restrictions that may interfere with the quality of life in women with breast cancer.     

Development and Psychometric Properties of a Computer-Based Standardized Emotional Competence Inventory (MeKKi) for Preschoolers and School-Aged Children

Child Psychiatry & Human Development - A computer-based emotional competence inventory for preschoolers and school-aged children (MeKKi) was developed to assess five components of emotional...     

Eurotransplant donor‐risk‐index and recipient factors: influence on long‐term outcome after liver transplantation – A large single‐center experience

The organ shortage has led to increased use of marginal organs. The Eurotransplant Donor‐Risk‐Index (ET‐DRI) was established to estimate outcome after Liver Transplantation (LT). Currently, data on impact of ET‐DRI on long‐term outcome for different indications and recipient conditions are missing. Retrospective, single‐center analysis of long‐term graft survival (GS) of 1767 adult primary LTs according to indication, labMELDcategory (1: ≤18; 2: >18–25; 3: >25–35; 4: >35), and ET‐DRI. Mean ET‐DRI in our cohort was 1.63 (±0.43). One‐, 10, and 15‐yr GS was 83.5%, 63.3%, and 54.8%. Long‐term GS was significantly influenced by ET‐DRI. Accordingly, four ET‐DRI categories were defined and analyzed with respect to underlying disease. Significant impact of these categories was observed for: Alcohol, cholestatic/autoimmune diseases (CD/AIH), and HCV, but not for HCC, HBV, cryptogenic cirrhosis, and acute liver failure. labMELD categories showed no significant influence on graft, but on patient survival. Matching ET‐DRI categories with labMELD revealed significant differences in long‐term GS for labMELDcategories 1, 2, and 3, but not 4. In multivariate analysis, HCV combined with ET‐DRI > 2 and labMELDcategory 3 combined with ET‐DRI > 2 emerged as negative predictors. To achieve excellent long‐term graft survival, higher risk organs (ET‐DRI > 1.4) should be used restrictively for patients with CD/AIH or HCV. Organs with ET‐DRI > 2 should be avoided in patients with a labMELD of >25–35.     

Mycobacterium tuberculosis heat-shock protein 70 impairs maturation of dendritic cells from bone marrow precursors, induces interleukin-10 production and inhibits T-cell proliferation in vitro

In different inflammatory disease models, heat-shock proteins (hsp) and hsp-derived peptides have been demonstrated to possess anti-inflammatory properties. While some studies have shown that hsp can directly interact with antigen-presenting cells, others report that bacterial hsp can induce specific T cells with regulatory phenotypes. Effective characterization of the immunomodulatory effects of hsp 70, however, has historically been confounded by lipopolysaccharide (LPS) contamination. In this study, we compared the effects of LPS-free Mycobacterial tuberculosis hsp 70 (TBhsp70) and its possible contaminants on dendritic cells (DC). We demonstrate herein that LPS-free TBhsp70 inhibits murine DC maturation in vitro, while LPS-contaminated TBhsp70 induces DC maturation. Mock recombinant preparations have no effect. In contrast to LPS, TBhsp70 does not induce tumour necrosis factor-alpha production by DC, but interleukin-10. In vivo, only LPS-contaminated TBhsp70 induces up-regulation of CD86 in splenic mature DC. Finally, TBhsp70 inhibited phytohaemagglutinin-induced T-cell proliferation. Our results support the hypothesis that TBhsp70 does not have inflammatory potential, but rather has immunosuppressive properties.     

Nucleotide sequence comparisons between several strains and isolates of human cytomegalovirus reveal alternate start codon usage

Summary Mutations abound in all viral populations, which are thus rendered adaptable to changes in environmental conditions. Human cytomegalovirus (HCMV) is an important human pathogen for investigating nucleotide sequence variations because they can affect its potential to cause disease. We have determined part of the nucleotide sequence of the Toledo strain and compared it to the published sequences of the strains AD169, Toledo, and Towne and of three clinical isolates. Overall nucleotide sequence divergence between strains AD169 and Toledo amounts to roughly 2%, with considerable variations across the viral genome. In aligning the Toledo nucleotide sequences with those of the other strains and clinical isolates, numerous amino-terminal extensions of the known open reading frames (ORFs) have been noted. These extensions carry additional AUG or non-canonical CUG or GUG translational initiation codons. CUG and GUG have previously been shown to serve as translational start codons in prokaryotic and eukaryotic systems. Six of the more closely inspected extensions start with an AUG, 26 with a CUG, and 26 with a GUG. Some of these extended sequences might bestow altered biological properties upon HCMV proteins. These ORF extensions are common to the sequenced genomes of most of the HCMV strains or isolates. Supporting evidence for their functionality comes from studies on HCMV mRNAs that were isolated from HCMV-infected human cells. Several of these viral mRNA sequences carry the identified ORF extensions. Moreover, in the amino-terminal ORF extensions, codon usage in general resembles that in the main parts of several of the HCMV genes analyzed for this property.