A comparison of forefoot stiffness in running and running shoe bending stiffness

This study characterizes the stiffness of the human forefoot during running. The forefoot stiffness, defined as the ratio of ground reaction moment to angular deflection of the metatarsophalangeal joint, is measured for subjects running barefoot. The joint deflection is obtained from video data, while the ground reaction moment is obtained from force plate and video data. The experiments show that during push-off, the forefoot stiffness rises sharply and then decreases steadily, showing that the forefoot behaves not as a simple spring, but rather as an active mechanism that exhibits a highly time-dependent stiffness. The forefoot stiffness is compared with the bending stiffness of running shoes. For each of four shoes tested, the shoe stiffness is relatively constant and generally much lower than the mean human forefoot stiffness. Since forefoot stiffness and shoe bending stiffness act in parallel (i.e., are additive), the total forefoot stiffness of the shod foot is dominated by that of the human foot.     

Uptake kinetics of 99Tc in common duckweed

The uptake of the nuclear waste product technetium-99 was studied in common duckweed (Lemna minor). In addition to measurements, a model involving two compartments in duckweed with different chemical forms of technetium was derived. The model was tested by chemical speciation, i.e. differentiating between reduced Tc-compounds and Tc(VII)O(4)(-). The TcO(4)(-) concentrations measured were in good agreement with those predicted by the model. Two processes determine technetium uptake: (1) transport of Tc(VII)O(4)(-) across the cell membrane, and (2) reduction of Tc(VII). The TcO(4)(-) concentration in duckweed reaches a steady state within 2 h while reduced Tc-compounds are stored, as a result of absence of release or re-oxidation processes. Bioaccumulation kinetic properties were derived by varying 99Tc concentration, temperature, nutrient concentrations, and light intensity. The reduction of technetium in duckweed was highly correlated with light intensity and temperature. At 25 degrees C the maximum reduction rate was observed at light intensities above 200 μmol m(-2) s(-1) while half of the maximum transformation rate was reached at 41 μmol m(-2) s(-1). Transport of TcO(4)(-) over the cell membrane requires about 9.4 kJ mol(-1), indicating an active transport mechanism. However, this mechanism behaved as first-order kinetics instead of Michaelis-Menten kinetics between 1x10(-14) and 2.5x10(-5) mol l(-1) TcO(4)(-). Tc uptake could not be inhibited by 10(-3) mol l(-1) nitrate, phosphate, sulphate or chloride.     

Positive Catch & Economic Benefits of Periodic Octopus Fishery Closures: Do Effective,Narrowly Targeted Actions ‘Catalyze’ Broader Management?

Overview

Eight years of octopus fishery records from southwest Madagascar reveal significant positive impacts from 36 periodic closures on: (a) fishery catches and (b) village fishery income, such that (c) economic benefits from increased landings outweigh costs of foregone catch. Closures covered ~20% of a village’s fished area and lasted 2-7 months.

Fishery Catches from Each Closed Site

Octopus landings and catch per unit effort (CPUE) significantly increased in the 30 days following a closure’s reopening, relative to the 30 days before a closure (landings: +718%, p<0.0001; CPUE: +87%, p<0.0001; n = 36). Open-access control sites showed no before/after change when they occurred independently of other management (“no ban”, n = 17/36). On the other hand, open-access control sites showed modest catch increases when they extended a 6-week seasonal fishery shutdown (“ban”, n = 19/36). The seasonal fishery shutdown affects the entire region, so confound all potential control sites.

Fishery Income in Implementing Villages

In villages implementing a closure, octopus fishery income doubled in the 30 days after a closure, relative to 30 days before (+132%, p<0.001, n = 28). Control villages not implementing a closure showed no increase in income after “no ban” closures and modest increases after “ban” closures. Villages did not show a significant decline in income during closure events.

Net Economic Benefits from Each Closed Site

Landings in closure sites generated more revenue than simulated landings assuming continued open-access fishing at that site (27/36 show positive net earnings; mean +$305/closure; mean +57.7% monthly). Benefits accrued faster than local fishers’ time preferences during 17-27 of the 36 closures. High reported rates of illegal fishing during closures correlated with poor economic performance.

Broader Co-Management

We discuss the implications of our findings for broader co-management arrangements, particularly for catalyzing more comprehensive management.     

Decreased hypertrophic differentiation accompanies enhanced matrix formation in co-cultures of outer meniscus cells with bone marrow mesenchymal stromal cells

Introduction

The main objective of this study was to determine whether meniscus cells from the outer (MCO) and inner (MCI) regions of the meniscus interact similarly to or differently with mesenchymal stromal stem cells (MSCs). Previous study had shown that co-culture of meniscus cells with bone marrow-derived MSCs result in enhanced matrix formation relative to mono-cultures of meniscus cells and MSCs. However, the study did not examine if cells from the different regions of the meniscus interacted similarly to or differently with MSCs.

Methods

Human menisci were harvested from four patients undergoing total knee replacements. Tissue from the outer and inner regions represented pieces taken from one third and two thirds of the radial distance of the meniscus, respectively. Meniscus cells were released from the menisci after collagenase treatment. Bone marrow MSCs were obtained from the iliac crest of two patients after plastic adherence and in vitro culture until passage 2. Primary meniscus cells from the outer (MCO) or inner (MCI) regions of the meniscus were co-cultured with MSCs in three-dimensional (3D) pellet cultures at 1:3 ratio, respectively, for 3 weeks in the presence of serum-free chondrogenic medium containing TGF-β1. Mono-cultures of MCO, MCI and MSCs served as experimental control groups. The tissue formed after 3 weeks was assessed biochemically, histochemically and by quantitative RT-PCR.

Results

Co-culture of inner (MCI) or outer (MCO) meniscus cells with MSCs resulted in neo-tissue with increased (up to 2.2-fold) proteoglycan (GAG) matrix content relative to tissues formed from mono-cultures of MSCs, MCI and MCO. Co-cultures of MCI or MCO with MSCs produced the same amount of matrix in the tissue formed. However, the expression level of aggrecan was highest in mono-cultures of MSCs but similar in the other four groups. The DNA content of the tissues from co-cultured cells was not statistically different from tissues formed from mono-cultures of MSCs, MCI and MCO. The expression of collagen I (COL1A2) mRNA increased in co-cultured cells relative to mono-cultures of MCO and MCI but not compared to MSC mono-cultures. Collagen II (COL2A1) mRNA expression increased significantly in co-cultures of both MCO and MCI with MSCs compared to their own controls (mono-cultures of MCO and MCI respectively) but only the co-cultures of MCO:MSCs were significantly increased compared to MSC control mono-cultures. Increased collagen II protein expression was visible by collagen II immuno-histochemistry. The mRNA expression level of Sox9 was similar in all pellet cultures. The expression of collagen × (COL10A1) mRNA was 2-fold higher in co-cultures of MCI:MSCs relative to co-cultures of MCO:MSCs. Additionally, other hypertrophic genes, MMP-13 and Indian Hedgehog (IHh), were highly expressed by 4-fold and 18-fold, respectively, in co-cultures of MCI:MSCs relative to co-cultures of MCO:MSCs.

Conclusions

Co-culture of primary MCI or MCO with MSCs resulted in enhanced matrix formation. MCI and MCO increased matrix formation similarly after co-culture with MSCs. However, MCO was more potent than MCI in suppressing hypertrophic differentiation of MSCs. These findings suggest that meniscus cells from the outer-vascular regions of the meniscus can be supplemented with MSCs in order to engineer functional grafts to reconstruct inner-avascular meniscus.     

Microbial production host selection for converting second-generation feedstocks into bioproducts

Although many secondary metabolites with diverse biological activities have been isolated from myxobacteria, most strains of these biotechnologically important gliding prokaryotes remain difficult to handle genetically. In this study we describe the new fast growing myxobacterial thermophilic isolate GT-2 as a heterologous host for the expression of natural product biosynthetic pathways isolated from other myxobacteria. According to the results of sequence analysis of the 16S rDNA, this moderately thermophilic isolate is closely related to Corallococcus macrosporus and was therefore named C. macrosporus GT-2. Fast growth of moderately thermophilic strains results in shorter fermentation and generation times, aspects which are of significant interest for molecular biological work as well as production of secondary metabolites. Development of a genetic manipulation system allowed the introduction of the complete myxochromide biosynthetic gene cluster, located on a transposable fragment, into the chromosome of GT-2. Genetic engineering of the biosynthetic gene cluster by promoter exchange leads to much higher production of myxochromides in the heterologous host C. macrosporus GT-2 in comparison to the original producer Stigmatella aurantiaca and to the previously described heterologous host Pseudomonas putida (600 mg/L versus 8 mg/L and 40 mg/L, respectively).     

Familial social structure and socially driven genetic differentiation in Hawaiian short‐finned pilot whales

Social structure can have a significant impact on divergence and evolution within species, especially in the marine environment, which has few environmental boundaries to dispersal. On the other hand, genetic structure can affect social structure in many species, through an individual preference towards associating with relatives. One social species, the short‐finned pilot whale (Globicephala macrorhynchus), has been shown to live in stable social groups for periods of at least a decade. Using mitochondrial control sequences from 242 individuals and single nucleotide polymorphisms from 106 individuals, we examine population structure among geographic and social groups of short‐finned pilot whales in the Hawaiian Islands, and test for links between social and genetic structure. Our results show that there are at least two geographic populations in the Hawaiian Islands: a Main Hawaiian Islands (MHI) population and a Northwestern Hawaiian Islands/Pelagic population (F_ST and Φ_ST p < .001), as well as an eastern MHI community and a western MHI community (F_ST p = .009). We find genetically driven social structure, or high relatedness among social units and clusters (p < .001), and a positive relationship between relatedness and association between individuals (p < .0001). Further, socially organized clusters are genetically distinct, indicating that social structure drives genetic divergence within the population, likely through restricted mate selection (F_ST p = .05). This genetic divergence among social groups can make the species less resilient to anthropogenic or ecological disturbance. Conservation of this species therefore depends on understanding links among social structure, genetic structure and ecological variability within the species.     

Splinting or surgery for carpal tunnel syndrome? Design of a randomized controlled trial [ISRCTN18853827]

Background  

Carpal tunnel syndrome is a common disorder, which can be treated with surgery or conservative options. However, there is insufficient evidence and no consensus among physicians with regard to the preferred treatment for carpal tunnel syndrome. Therefore, a randomized controlled trial is conducted to compare the short- and long-term efficacy of surgery and splinting in patients with carpal tunnel syndrome. An attempt is also made to avoid the (methodological) limitations encountered in earlier trials on the efficacy of various treatment options for carpal tunnel syndrome.