CD19-positive antibody-secreting cells provide immune memory.

Long-lived antibody-secreting cells (ASCs) are critical for the maintenance of humoral immunity through the continued production of antibodies specific for previously encountered pathogen or vaccine antigens. Recent reports describing humoral immune memory have suggested the importance of long-lived CD19- bone marrow (BM) ASCs, which secrete antibodies recognizing previously encountered vaccine antigens. However, these reports do not agree upon the unique contribution of the CD19+ BM ASC subset toward humoral immunity. Here, we found both CD19+ and negative ASCs from human BM were similar in functional capacity to react to a number of vaccine antigens via ELISpot assays. The CD19+ cells were the predominant ASC population found in lymphoid tissues, and unlike the CD19- ASCs, which were found only in spleen and BM, the CD19+ ASCs were found in tonsil and blood. CD19+ ASCs from the BM, spleen, and tonsil were capable of recognizing polio vaccine antigens, indicating the CD19+ ASC cells play a novel role in long-lasting immune defense. Comparative gene expression analysis indicated CD19+ and negative BM ASCs differed significantly by only 14 distinct messenger RNAs and exhibited similar gene expression for cell cycle, autophagy, and apoptosis control necessary for long life. In addition, we show identical CDR-H3 sequences found on both BM ASC subsets, indicating a shared developmental path. Together, these results provide novel insight for the distribution, function, genetic regulation, and development of long-lived ASCs and may not only impact improved cell therapies but also enhance strategies for vaccine development.

Exposure to low-frequency electromagnetic fields does not alter HSP70 expression or HSF-HSE binding in HL60 cells.

Environmental exposure to extremely low-frequency electromagnetic fields (ELF EMFs) has been identified as a possible contributor to increased cancer incidence and other diseases. In vitro studies designed to probe for biological mechanisms that might explain such relationships have included several studies of gene expression. While gene expression studies have focused on MYC, effects of ELF EMFs on the expression of beta-actin, histone H2B, beta-tubulin, SRC, FOS and JUN have also been reported. In addition, some investigators have reported both an induction of HSP70 expression and an increase in HSF-HSE binding in HL60 (human promyelocytic leukemia) cells after exposure to a 60 Hz magnetic field. In this study, HL60 cells were exposed to a weak 60 Hz magnetic field (6.3 or 8.0 microT) or to a positive control heat shock (42 or 44 degrees C). While heat shock led to reproducible induction of HSP70 expression and HSF-HSE binding, no significant effect of exposure to ELF EMFs on either of these end points was observed.

Exposure of Daudi cells to low-frequency magnetic fields does not elevate MYC steady-state mRNA levels.

The effect of extremely low-frequency electromagnetic field (ELF EMF) exposures to human health has been widely debated. Epidemiological studies have found a possible correlation between increased cancer incidence and environmental ELF EMF exposures. Results from in vitro studies performed to examine the possible underlying bioeffects of ELF EMFs have varied greatly. Reported effects range from robust and reproducible effects to undetectable. In this study, Daudi cells were exposed to 60 Hz magnetic fields for 20, 40 or 60 min at flux densities of 12.5, 50, 100 or 500 microT. Exposures were performed in the Regional ELF-EMF Exposure Facility (Rockville, MD) to minimize variables that might contribute to a false positive effect. Exposures included sham/sham, exposed/sham or sham/exposed, and were performed with blinding with respect to type of exposure. 12-O-Tetradecanoylphorbol-13-acetate (TPA) treatment was used as a positive control. Total cellular RNA was isolated using a single-step technique. Human MYC expression was measured by northern blot hybridization as an indicator of the responsiveness of Daudi cells to experimental conditions. Beta-2-microglobulin (B2M) expression was measured simultaneously as an internal control. Exposure to a 60 Hz magnetic field did not significantly alter MYC expression in Daudi cells under any of the exposure conditions.

An in vitro biomechanical study of the static stabilizing effect of lateral prophylactic knee bracing on medial stability.

We attempted to determine if the selected lateral prophylactic knee braces (ie, Anderson Knee Stabler-101W, Don Joy-PKG and McDavid Knee Guard) were effective at stabilizing the medial collateral ligament against valgus loading to the knee joint. We tested 23 volunteer subjects under each of three braced conditions, plus a nonbraced condition. Applying stress to the lower leg of the subjects, we measured and recorded the linear displacement of the tibia in abduction and/or adduction. We analyzed the data, using a repeated measures ANOVA. There were no differences between the bracing conditions. We concluded that the three knee braces were not effective at stabilizing the knee joint from a static valgus force.

Soft Contact Lenses for Sports.

Good vision is essential in sports, but many athletes go without correction because the solution is worse than the problem. This study shows that soft contact lenses correct more than vision.

A novel oncogenic role for the miRNA-506-514 cluster in initiating melanocyte transformation and promoting melanoma growth.

Malignant melanoma is the most aggressive form of skin cancer and its incidence has doubled in the last two decades. It represents only 4% of skin cancer cases per year, but causes as many as 74% of skin cancer deaths. Early detection of malignant melanoma is associated with survival rates of up to 90%, but later detection (stage III to stage IV) is associated with survival rates of only 10%. Dysregulation of microRNA (miRNA) expression has been linked to tumor development and progression by functioning either as a tumor suppressor, an oncogene or a metastasis regulator in multiple cancer types. To understand the role of miRNA in the pathogenesis of malignant melanoma and identify biomarkers of metastasis, miRNA expression profiles in skin punches from 33 metastatic melanoma patients and 14 normal healthy donors were compared. We identified a cluster of 14 miRNAs on the X chromosome, termed the miR-506-514 cluster, which was consistently overexpressed in nearly all melanomas tested (30-60 fold, P<0.001), regardless of mutations in N-ras or B-raf. Inhibition of the expression of this cluster as a whole, or one of its sub-clusters (Sub-cluster A) consisting of six mature miRNAs, led to significant inhibition of cell growth, induction of apoptosis, decreased invasiveness and decreased colony formation in soft agar across multiple melanoma cell lines. Sub-cluster A of the miR-506-514 cluster was critical for maintaining the cancer phenotype, but the overexpression of the full cluster was necessary for melanocyte transformation. Our results provide new insights into the functional role of this miRNA cluster in melanoma, and suggest new approaches to treat or diagnose this disease.

Knee stability and knee ligament injuries.

Controversy exists on the relationship of knee ligament stability to knee injuries. Subjective evaluation of joint tightness or looseness has been proposed as a criterion for prescribing selective corrective strengthening or stretching exercises. Biomechanical studies of knee ligament stability were performed on 401 college football players from 1969 to 1971. Forty-three knee ligament injuries occurred during this period of time, 19 (44.2%) in "loose-jointed" players and 24 (55.8%) in "tight-jointed" players. Joint laxity tests were performed on 72 college football players; the distribution of college football players failing to perform each of the tests was quite different from that reported for professional football players. There was no relationship between the subjective joint laxity tests and the objective biomechanical tests of knee ligament stability. We conclude that it is not possible to predict knee injuries by subjective evaluations of joint laxity or by objective biomechanical knee ligament evaluations and that exercise programs based on subjective studies are therefore not sound.

Torques developed by different types of shoes on various playing surfaces.

The purpose of this investigation was to determine the effects of shoe type, playing surface, weight supported and stance position upon the torques developed at the shoe-turf interface. The study was predicated upon the assumption that many knee injuries are torque-related and due to foot fixation, either by rigid cleating or by excessive traction between the shoe and playing surface. A laboratory apparatus was designed to measure the torque developed by various shoe-surface combinations. Under investigation were 11 shoe types, three artificial surfaces and natural grass, two player weights, and two player foot-stance positions. Torque data were gathered using impact loading, with an impact energy that is probably often experienced under competitive playing conditions. Resulting data indexed the shoes according to the mean torques developed on each of the playing surfaces, and comparisons of torque data with field studies by other researchers suggested which shoe-surface combinations might be the most potentially hazardous.

Effects on traction of outsole composition and hardnesses of basketball shoes and three types of playing surfaces.

The purposes of this investigation were to determine the effects of outsole composition and hardness, playing surfaces and player weight on the dynamic torque, traction forces and static drag developed at the shoe-surface interface. Basketball shoes of polyurethane and elastomer outsoles, each of three different hardnesses, were tested on clean and dusty hardwood floor samples, and on a sample of an artificial gymnasium flooring. The tests were conducted using a laboratory apparatus which included a player leg assembly with simulation of two player weights. Dynamic torque, traction forces from side and rear impacts and static drag were measured at the shoe surface interface. The results indicated that in basketball the magnitude of the resistance forces and torques are influenced by the outsole material and outsole hardness of the shoes, the playing surface and player weights.