Seeing It Helps: Movement-related Back Pain Is Reduced by Visualization of the Back During Movement

OBJECTIVES:: The aim of this study was to determine whether visualization of the back influenced parameters of movement-related pain in people with chronic nonspecific low back pain. METHODS:: We used a randomized cross-over experiment in which 25 participants performed repeated lumbar spine movements under 2 conditions. In the visual feedback condition, patients were able to visualize their back as it moved by the use of mirrors. In the control condition, the mirror was covered so no visualization of the back was possible. RESULTS:: The average postmovement pain intensity after participants had moved with visual feedback was less (35.5±22.8 mm) than when they moved without visual feedback (44.7±26.0 mm). This difference was statistically significant (mean difference=9.3, 95% confidence interval: 2.8-15.7 F(1,22)=8.82, P=0.007). The average time to ease after participants had moved with visual feedback was shorter (44.5 s±53.8) than when they moved without visual feedback (94.4 s±80.7). This difference was also statistically significantly (mean difference=49.9, 95% confidence interval: 19.3-80.6, F(1,22)=8.82, P=0.003). DISCUSSION:: Patients with chronic nonspecific low back pain reported less increase in pain and faster resolution of pain when moving in an environment that enabled them to visualize their back. This is consistent with emerging research on the use of mirror visual feedback in other long-standing pain problems and suggests that similar lines of inquiry may be worth pursuing in the chronic nonspecific low back pain population.     

Effect of moderate intensity resistance training during weight loss on body composition and physical performance in overweight older adults

The impact of resistance training has not been thoroughly examined in overweight older adults undergoing weight loss. Subjects (n = 27) were overweight and obese (BMI 31.7 ± 3.6 kg/m²) older (age 67 ± 4 years) adults and were randomized into either a 10-week Dietary Approaches to Stop Hypertension for weight loss diet (DASH, n = 12) or DASH plus moderate intensity resistance training (DASH-RT, n = 15). Outcomes included weight loss, total body and mid-thigh composition, muscle and physical function. There were no significant weight loss differences between the DASH-RT and DASH groups (−3.6 ± 0.8 vs. −2.0 ± 0.9%, p = 0.137). The DASH-RT group had a greater reduction in body fat than the DASH group (−4.1 ± 0.9 vs. −0.2 ± 1.0 kg, p = 0.005). The DASH-RT group had greater changes in lean mass (+0.8 ± 0.4 vs. −1.4 ± 0.4 kg, p = 0.002) and strength (+60 ± 18 vs. −5 ± 9 N, p = 0.008) than the DASH group. There were favorable changes in mid-thigh composition variables in the DASH-RT group that were different than the lack of changes observed in the DASH group, except for intermuscular adipose tissue. Both groups experienced decreases in 400-m walk times showed (DASH −36 ± 11 s, DASH-RT −40 ± 7 s) with no differences between groups. Moderate intensity resistance training during weight loss appears to improve fat mass and thigh composition, but weight loss only does not. However, global measures of physical functioning may improve with a weight loss-only program.     

A comparison of the functionality and in vivo phenotypic stability of cartilaginous tissues engineered from different stem cell sources

Joint-derived stem cells are a promising alternative cell source for cartilage repair therapies that may overcome many of the problems associated with the use of primary chondrocytes (CCs). The objective of this study was to compare the in vitro functionality and in vivo phenotypic stability of cartilaginous tissues engineered using bone marrow-derived stem cells (BMSCs) and joint tissue-derived stem cells following encapsulation in agarose hydrogels. Culture-expanded BMSCs, fat pad-derived stem cells (FPSCs), and synovial membrane-derived stem cells (SDSCs) were encapsulated in agarose and maintained in a chondrogenic medium supplemented with transforming growth factor-β3. After 21 days of culture, constructs were either implanted subcutaneously into the back of nude mice for an additional 28 days or maintained for a similar period in vitro in either chondrogenic or hypertrophic media formulations. After 49 days of in vitro culture in chondrogenic media, SDSC constructs accumulated the highest levels of sulfated glycosaminoglycan (sGAG) (～2.8% w/w) and collagen (～1.8% w/w) and were mechanically stiffer than constructs engineered using other cell types. After subcutaneous implantation in nude mice, sGAG content significantly decreased for all stem cell-seeded constructs, while no significant change was observed in the control constructs engineered using primary CCs, indicating that the in vitro chondrocyte-like phenotype generated in all stem cell-seeded agarose constructs was transient. FPSCs and SDSCs appeared to undergo fibrous dedifferentiation or resorption, as evident from increased collagen type I staining and a dramatic loss in sGAG content. BMSCs followed a more endochondral pathway with increased type X collagen expression and mineralization of the engineered tissue. In conclusion, while joint tissue-derived stem cells possess a strong intrinsic chondrogenic capacity, further studies are needed to identify the factors that will lead to the generation of a more stable chondrogenic phenotype.     

Controlling the contractile strength of engineered cardiac muscle by hierarchal tissue architecture

The heart is a muscular organ with a wrapping, laminar structure embedded with neural and vascular networks, collagen fibrils, fibroblasts, and cardiac myocytes that facilitate contraction. We hypothesized that these non-muscle components may have functional benefit, serving as important structural alignment cues in inter- and intra-cellular organization of cardiac myocytes. Previous studies have demonstrated that alignment of engineered myocardium enhances calcium handling, but how this impacts actual force generation remains unclear. Quantitative assays are needed to determine the effect of alignment on contractile function and muscle physiology. To test this, micropatterned surfaces were used to build 2-dimensional myocardium from neonatal rat ventricular myocytes with distinct architectures: confluent isotropic (serving as the unaligned control), confluent anisotropic, and 20?μm spaced, parallel arrays of multicellular myocardial fibers. We combined image analysis of sarcomere orientation with muscular thin film contractile force assays in order to calculate the peak sarcomere-generated stress as a function of tissue architecture. Here we report that increasing peak systolic stress in engineered cardiac tissues corresponds with increasing sarcomere alignment. This change is larger than would be anticipated from enhanced calcium handling and increased uniaxial alignment alone. These results suggest that boundary conditions (heterogeneities) encoded in the extracellular space can regulate muscle tissue function, and that structural organization and cytoskeletal alignment are critically important for maximizing peak force generation.     

Is mortality among under‐five children in Nairobi slums seasonal?

Objective  To investigate the seasonal pattern of overall mortality among children aged below 5 years living in two informal settlements in Nairobi City.
Methods  We used data collected from January 2003 to December 2005 in the Nairobi Urban Health and Demographic Surveillance System on demographic events (birth, death, and migration). Analyses of seasonal effects on under-five mortality are based on Poisson regression controlling for sex, age, study site and calendar year.
Results  During the study period, there were 17 878 children below 5 years in the study sites. Overall 436 under-five deaths were recorded. The overall death rate for the under-five children was 19.95 per 1 000 person years. There is a significant seasonal variation of under-five mortality. The mortality risk was significantly higher in the second and third quarters of year than in the fourth quarter (RR = 1.6, CI: 1.3–2.2 and RR = 1.5, CI: 1.1–2.0).
Conclusion  This paper demonstrates that overall mortality among under-five children in the urban poor is seasonal. Overall during the second quarter of the year, the death rate increases by nearly twofold. This evidence generated here may help to support well targeted interventions in reducing under-five mortality in the slums.     

Yeast coexpression of human papillomavirus types 6 and 16 capsid proteins

The L1 and L2 capsid proteins of animal and human papillomaviruses (HPVs) can self-assemble into virus-like particles (VLPs) that closely resemble native virions. The use of different animal models shows that VLPs can be very efficient at inducing a protective immune response. However, studies with infectious HPV virions and VLPs of different HPV types indicate that the immune response is predominantly type-specific. We have generated a diploid yeast strain that coexpresses the L1 and L2 capsid proteins of both HPV-6b and HPV-16, and we have purified fully assembled VLPs banding in a cesium chloride gradient at the expected density of 1.29-1.3 mg/ml. Experimental evidence strongly indicated that the four proteins coassembled into VLPs. Western blot analysis, using anti-HPV-6 and anti-HPV-16 L1-specific monoclonal antibodies and type-specific L2 antisera, demonstrated that all four proteins copurified. Most importantly, immunoprecipitation experiments, carried out using type-specific anti-L1 monoclonals and either total yeast cell extracts or purified VLPs, confirmed the interaction and the formation of covalent disulfide bonds between the two L1 proteins. Finally, HPV-6/16 VLPs administered to mice induced conformational antibodies against both L1 protein types. These results suggest that coexpression of different capsid proteins may provide new tools for the induction of antibodies directed against multiple HPV types.     

Statistical characterization of the pubertal growth spurt

Background: This is a methodical investigation into the problem of estimating parameters for the pubertal spurt (PS). The variability involved in determining the timing, intensity and duration of the PS for height, leg height and biiliac width is estimated via a realistic simulation. Further, a decomposition of adolescent growth into a component due to the pubertal peak and one due to ongoing prepubertal velocity is evaluated.

Methods: Data for 120 boys and 112 girls are available from 4 weeks to adulthood. The curve-fitting method is kernel estimation for distance, velocity and acceleration.

Results: The age of peak velocity and the age of stopping of the PS are well determined. In contrast, the age of onset of the PS is less well determined. Intensity is less variable for the parameter peak velocity than for maximal acceleration. It is feasible to decompose adolescent growth into a component due to the pubertal peak and one due to ongoing prepubertal growth.

Conclusions: Nonparametric curve-fitting methods which do not rely on a parametric growth model can be successfully used to extract individual characteristics of the PS.

Hintergrund: Dieses ist eine methodische Untersuchung zum Problem der Schätzparameter des puberalen Wachstumsspurts (PS). Die Variabilität, die bei der Bestimmung des Zeitpunktes, der Intensität und Dauer des PS bei der Körperhöhe, der Beinhöhe und bei der Beckenbreite auftritt, wird über eine realistische Simulation geschätzt. Weiterhin wird das Wachstum in der Adoleszens hinsichtlich des puberalen Wachstumsgipfels und der fortwährenden prepuberalen Geschwindigkeit ausgewertet. Methoden: Für 120 Jungen und 112 Mädchen liegen Daten von einem Alter von 4 Wochen bis zum Erwachsenenalter vor. Als Kurven-Glättungsmethode wurde die Kernel-Schätzung für Zunahme, Geschwindigkeit und Beschleunigung genutzt. Resultate: Das Alter bei der maximalen Wachstumsgeschwindigkeit und das Alter beim Abschluß des PS sind gut feststellbar. Demgegenüber ist das Alter des Einsetzens des PS weniger gut feststellbar. Die Intensität der maximalen Wachstumsgeschwindigkeit ist weniger variabel als die Intensität der maximalen Beschleunigung. Es ist möglich das Wachstum in der Adoleszens in einen Bereich des puberalen Wachstumsgipfel und ein fortwährendes prepuberales Wachstums zu unterteilen. Schlußfolgerungen: Nichtparametrische Kurvenglättungsmethoden, welche nicht auf einem parametrischen Wachstumsmodell beruhen, können erfolgreich verwendet werden, um individuelle Charakteristiken des PS herauszuarbeiten.

Arrière plan: ceci est une analyse méthodique du problème de l'estimation des paramètres de la poussée pubertaire (PP). La variabilité de détermination de la chronologie, de l'intensité et de la durée de la PP pour la stature, la hauteur de la jambe et la largeur biiliaque, est estimée au moyen d'une simulation réaliste, puis est effectuée une décomposition de la poussée de l'adolescence en un composant du au pic pubertaire et en un autre du à la continuation de la vélocité prépubertaire. Méthodes: des données sur 120 garçons et sur 112 filles sont disponibles de l'âge de quatre semaines jusqu'à l'état adulte. La méthode d'ajustement des courbes est celle de l'estimation de fond (kernel), pour la distance, la vélocité et l'accélération. Résultats: l'âge de la vélocité de pic et celui de l'arrêt de la PP sont bien déterminés. Par contre, l'âge au début de la PP est moins précis. L'intensité est moins variable pour la vélocité de pic que pour l'accélération maximale. Il est possible de décomposer la poussée de l'adolescence en un composant du au pic pubertaire et un autre du à la poursuite de la croissance prépubertaire. Conclusions: les méthodes non paramétriques d'ajustement des courbes, qui ne reposent pas sur un modèle paramétrique de croissance peuvent être utilisées avec succès pour extraire des caractéristiques individuelles de la PP.     

Contribution of growth phases to adult size

Based on the data of the First Zurich Longitudinal Growth Study we investigate how interindividual differences in adult size arise in the variables leg height, sitting height and standing height, arm length, biiliac width and bihumeral width. Specifically, we are also interested in the question of whether across sexes and variables the same growth phases and the same parameters are predictive for achieving a certain adult size. A rather complex pattern emerges, demonstrating that regulation of growth is not the same for boys and girls and moreover is not the same for the six anthropometric variables studied. Prepubertal growth is characterized by its intensity (average velocity) and by its duration. Whereas duration has by itself no appreciable influence on adult size, prepubertal intensity determines adult size to a high degree across all variables and both sexes. The intensity of prepubertal growth determines adult size to a larger degree for boys than for girls. For a given size at the end of the prepubertal period, a small duration enhances the chance of obtaining a large adult size. Compared with prepubertal growth, the amount of variance of adult size explained is small for pubertal parameters, and - with respect to linear measures - significant for girls only. A small duration of prepubertal growth is in the following mainly compensated by a stronger pubertal spurt (PS), to a varying degree across variables. The overall picture which emerges indicates that sitting height - and to a lesser extent bihumeral width - develop in a more irregular fashion than the variables biiliac width and leg height.     

Growth of early and late maturers

Background: This is a study on the growth of subgroups of normal children, maturing early or late, in the variables height, leg and sitting height, arm length, biiliac and bihumeral width. While a longer growth period affects adult height only marginally, less is known about the other variables. It is also of interest to see in what way a shorter growth period is compensated by a higher velocity.

Methods: Out of 120 boys and 112 girls followed from 4 weeks until adulthood, subgroups of 40 boys and 37 girls were formed with respect to the average timing (across variables) of the pubertal spurt as an indicator of maturity.

Results: Only leg height shows a smaller adult size for early maturers. The shorter growth period is compensated by a higher prepubertal velocity and a higher level in pubertal years. The pubertal peak is a little larger for early maturing boys but not for girls.

Conclusions: There is an inherent pacemaker for growth that leads to the same adult size for a shorter growth period via a higher basic intensity. Legs are an exception since late maturers have, on average, longer legs as adults.

Hintergrund: Es handelt sich um eine Studie über das Wachstum von Untergruppen früh- oder spätreifender normaler Kinder bezüglich der Variablen Körperlänge, Beinlänge und Sitzhöhe, Armlänge, Beckenbreite und Ellbogenbreite. Während eine längere Wachstumperiode die Erwachsenenkörperhöhe nur unbedeutend beeinflusst, ist über die anderen Variablen wenig bekannt. Es ist daher interessant zu sehen, in welcher Weise eine kürzere Wachstumsperiode durch eine höhere Wachstumsgeschwindigkeit kompensiert wird. Methodik: Aus einer Gruppe von 120 Jungen und 112 Mädchen, die vom Alter von 4 Wochen bis zum Erwachsenenalter untersucht wurden, wurden Untergruppen von 40 Jungen und 37 Mädchen gebildet. Dies erfolgte mit Bezug auf den durchschnittlichen Zeitpunkt (ermittelt aus allen Variablen) des puberalen Spurts als Reifungsindikator. Ergebnisse: Nur die Beinlänge zeigt eine geringere Erwachsenengröße bei den Probanden mit früher Reife. Die kürzere Wachstumsperiode wird durch eine höhere präpuberale Geschwindigkeit und ein höheres Niveau in den Pubertätsjahren kompensiert. Der puberale Gipfel ist etwas größer bei den Jungen mit früher Reife, nicht dagegen bei den Mädchen. Schlussfolgerungen: Es gibt einen inhärenten Schrittmacher für das Wachstum, welcher bei einer kürzeren Wachstumsperiode über eine höhere Basisintensität zur gleichen Erwachsenengröße führt. Die Beinlänge bildet eine Ausnahme, da die spät Reifenden im Durchschnitt als Erwachsene längere Beine haben.

Arrière plan: il s'agit d'une étude sur la croissance de la la stature, hauteur de la jambe et de la taille-assis, de la longueur du bras et des largeurs bihumérale et biiliaque, chez des sous-groupes d'enfants normaux àmaturation lente ou rapide. Alors qu'on sait qu'une plus longue période de croissance n'affecte la stature adulte que de façon marginale, peu de choses sont connues quant aux autres variables. Il est également intéressant de voir dans quelle mesure une période de croissance plus courte est compensée par une vélocité plus grande. Méthode: à partir d'échantillons de 120 garçons et 112 filles suivis de l'âge de quatre semaines jusqu'à l'état adulte, on a formédes sous-groupes de 40 garçons et de 37 filles, selon la chronologie moyenne (calculée sur l'ensemble des variables) de la poussée pubertaire, considérée comme un indicateur de maturité. Résultats: seule la hauteur de la jambe exprime une plus petite taille adulte chez les enfants à maturation rapide. La période de croissance plus courte est compensée par une vélocité prépubertaire plus élevée et un plus haut niveau pendant la puberté. Le pic pubertaire est un peu plus marqué pour les garçons à maturation précoce, mais non pour les filles. Conclusions: il existe un régulateur inhérent au processus de croissance, qui conduit à une dimension adulte identique lorsque se raccourcit la période de croissance, via une intensité de base plus grande. Les jambes en sont une exception, car les enfants à maturation tardive ont en moyenne de plus longues jambes à l'état adulte.