Efficacy of a progressive walking program and glucosamine sulphate supplementation on osteoarthritic symptoms of the hip and knee: a feasibility trial

Introduction  

Management of osteoarthritis (OA) includes the use of non-pharmacological and pharmacological therapies. Although walking is commonly recommended for reducing pain and increasing physical function in people with OA, glucosamine sulphate has also been used to alleviate pain and slow the progression of OA. This study evaluated the effects of a progressive walking program and glucosamine sulphate intake on OA symptoms and physical activity participation in people with mild to moderate hip or knee OA.     

Investigation of mitochondrial sequence variants associated with aminoglycoside-induced ototoxicity in South African TB patients on aminoglycosides

A known side effect of aminoglycoside antibiotics is the development of permanent hearing loss. As South Africa is currently facing a tuberculosis (TB) epidemic, with an increasing number of multi-drug resistant tuberculosis (MDR-TB) infections, the use of aminoglycosides is on the increase. It is therefore important to determine whether the mitochondrial mutations associated with aminoglycoside-induced hearing loss occur at high frequencies in particular ethnic groups in our population. A total of 115 mainly MDR-TB patients all on aminoglycosides and 439 controls representative of the main ethnic groups in South Africa were screened for six mutations using the SNaPshot technique. Furthermore, the mitochondrial genomes of eight patients with ototoxicity were sequenced. Homoplasmic mutations were found in controls (A1555G in 0.9% of Black controls and A827G in 1.1% of Afrikaner controls) which reveal that a significant proportion of the South African population is genetically predisposed to developing aminoglycoside-induced hearing loss. The 961delT+insC_(n) and T961G variants were found at frequencies of >1% indicating that both are probably non-pathogenic polymorphisms. Sequencing of the entire mitochondrial genome in eight patients did not reveal any mutations in the MT-RNR1 gene. However, two potentially pathogenic variants, T10114C (I19T in MT-ND3) and T15312C (I189T in MT-CYB) were found that may impact on the oxidative phosphorylation capacity and warrant further investigation for their possible role in this disorder. It is imperative that the genetic basis of this potentially preventable condition be investigated, particularly in countries where aminoglycosides are still commonly used, in order to identify individuals and/or ethnic groups who are at risk for this type of hearing loss.     

Five hundred microsatellite loci for Peromyscus

Mice of the genus Peromyscus, including several endangered subspecies, occur throughout North America and have been important models for conservation research. We describe 526 primer pairs that amplify microsatellite DNA loci for Peromyscus maniculatus bairdii, 467 of which also amplify in Peromyscus polionotus subgriseus. For 12 of these loci, we report diversity data from a natural population. These markers will be an important resource for future genomic studies of Peromyscus evolution and mammalian conservation.     

Angiopoietin-2 deficiency decelerates age-dependent vascular changes in the mouse retina.

Retinae of aged humans show signs of vascular regression. Vascular regression involves a mismatch between Angiopoietin-2 (Ang-2) and vascular endothelial growth factor (VEGF) expression. We used heterozygous Ang-2 deficient (Ang2LacZ) mice to evaluate murine retinal vascular changes and gene expression of growth factors. Vascular changes were assessed by quantitative retinal morphometry and gene expression levels of growth factors were measured by quantitative PCR. The numbers of endothelial cells and pericytes did not change in the Ang2LacZ retinae with age, whereas they decreased throughout the age spectrum studied in the wild type retinae. Moreover, vascular regression significantly decelerated in the heterozygous Ang2LacZ retinae (200% to 1 month), while the formation of acellular capillaries was significantly increased at 13 months in the wild type retinae (340% to 1 month). Gene expression analysis revealed that VEGF, Ang-1, PDGF-B and Ang2 mRNA levels were decreased in the wild type retinae at 9 month of age. However, the decrease of Ang-2 was smaller compared with other genes. While VEGF levels dropped in wild type mice up to 60% compared to 1 month, VEGF increased in heterozygous Ang-2 deficient retinae at an age of 9 months (141% to 1 month). Similarly, Ang-1 levels decreased in wild type mice (45% to 1 month), but remained stable in Ang2LacZ mice. These data suggest that Ang-2 gene dose reduction decelerates vasoregression in the retina with age. This effect links to higher levels of survival factors such as VEGF and Ang-1, suggesting that the ratio of these factors is critical for capillary cell survival.     

Reduced hybrid cluster proteins (HCP) from Desulfovibrio desulfuricans ATCC 27774 and Desulfovibrio vulgaris (Hildenborough): X-ray structures at high resolution using synchrotron radiation

The hybrid cluster proteins from the sulfate reducing bacteria Desulfovibrio desulfuricans ATCC 27774 ( Dd) and Desulfovibrio vulgaris strain Hildenborough ( Dv) have been isolated and crystallized anaerobically. In each case, the protein has been reduced with dithionite and the crystal structure of the reduced form elucidated using X-ray synchrotron radiation techniques at 1.25 A and 1.55 A resolution for Dd and Dv, respectively. Although the overall structures of the proteins are unchanged upon reduction, there are significant changes at the hybrid cluster centres. These include significant movements in the position of the iron atom linked to the persulfide moiety in the oxidized as-isolated proteins and the sulfur atom of the persulfide itself. The nature of these changes is described and the implications with respect to the function of hybrid cluster proteins are discussed.     

EPR analysis of multiple forms of [4Fe–4S]3+ clusters in HiPIPs

The electron paramagnetic resonance (EPR) spectrum from the [4Fe–4S]³⁺ cluster in several high-potential iron–sulfur proteins (HiPIPs) is complex: it is not the pattern of a single, isolated S=1/2 system. Multifrequency EPR from 9 to 130 GHz reveals that the apparent peak positions (g values) are frequency-independent: the spectrum is dominated by the Zeeman interaction plus g-strain broadening. The spectra taken at frequencies above the X-band are increasingly sensitive to rapid-passage effects; therefore, the X-band data, which are slightly additionally broadened by dipolar interaction, were used for quantitative spectral analysis. For a single geometrical [4Fe–4S]³⁺ structure the (Fe–Fe)⁵⁺ mixed-valence dimer can be assigned in six different ways to a pair of iron ions, and this defines six valence isomers. Systematic multicomponent g-strain simulation shows that the [4Fe–4S]³⁺ paramagnets in seven HiPIPs from different bacteria each consist of three to four discernible species, and these are assigned to valence isomers of the clusters. This interpretation builds on previous EPR analyzes of [4Fe–4S]³⁺ model compounds, and it constitutes a high-resolution extension of the current literature model, proposed from paramagnetic NMR studies.     

Cocoa flavanols lower vascular arginase activity in human endothelial cells in vitro and in erythrocytes in vivo

The availability of l-arginine can be a rate-limiting factor for cellular NO production by nitric oxide synthases (NOS). Arginase competes with NOS for l-arginine as the common substrate. Increased arginase activity has been linked to low NO levels, and an inhibition of arginase activity has been reported to improve endothelium-dependent vasorelaxation. Based on the above, we hypothesized that an increase in the circulating NO pool following flavanol consumption could be correlated with decreased arginase activity. To test this hypothesis we (a) investigated the effects of (−)-epicatechin and its structurally related metabolites on endothelial arginase expression and activity in vitro; (b) evaluated the effects of dietary flavanol-rich cocoa on kidney arginase activity in vivo; and (c) assessed human erythrocyte arginase activity following flavanol-rich cocoa beverage consumption in a double-blind intervention study with cross-over design. The results demonstrate that cocoa flavanols lower arginase-2 mRNA expression and activity in HUVEC. Dietary intervention with flavanol-rich cocoa caused diminished arginase activity in rat kidney and, erythrocyte arginase activity was lowered in healthy humans following consumption of a high flavanol beverage in vivo.     

Amazon Forest Structure from IKONOS Satellite Data and the Automated Characterization of Forest Canopy Properties

We developed an automated tree crown analysis algorithm using 1-m panchromatic IKONOS satellite images to examine forest canopy structure in the Brazilian Amazon. The algorithm was calibrated on the landscape level with tree geometry and forest stand data at the Fazenda Cauaxi (3.75° S, 48.37° W) in the eastern Amazon, and then compared with forest stand data at Tapajos National Forest (3.08° S, 54.94° W) in the central Amazon. The average remotely sensed crown width (mean ± SE) was 12.7 ± 0.1 m (range: 2.0–34.0 m) and frequency of trees was 76.6 trees/ha at Cauaxi. At Tapajos, remotely sensed crown width was 13.1 ± 0.1 m (range: 2.0–38.0 m) and frequency of trees was 76.4 trees/ha. At both Cauaxi and Tapajos, the remotely sensed average crown widths were within 3 percent of the crown widths derived from field measurements, although crown distributions showed significant differences between field-measured and automated methods. We used the remote sensing algorithm to estimate crown dimensions and forest structural properties in 51 forest stands (1 km²) throughout the Brazilian Amazon. The estimated crown widths, tree diameters (dbh), and stem frequencies differed widely among sites, while estimated biomass was similar among most sites. Sources of observed errors included an inability to detect understory crowns and to separate adjacent, intermingled crowns. Nonetheless, our technique can serve to provide information about structural characteristics of large areas of unsurveyed forest throughout Amazonia.     

Reinvestigation of the steady-state kinetics and physiological function of the soluble NiFe-hydrogenase I of Pyrococcus furiosus

Pyrococcus furiosus has two types of NiFe-hydrogenases: a heterotetrameric soluble hydrogenase and a multimeric transmembrane hydrogenase. Originally, the soluble hydrogenase was proposed to be a new type of H₂ evolution hydrogenase, because, in contrast to all of the then known NiFe-hydrogenases, the hydrogen production activity at 80°C was found to be higher than the hydrogen consumption activity and CO inhibition appeared to be absent. NADPH was proposed to be the electron donor. Later, it was found that the membrane-bound hydrogenase exhibits very high hydrogen production activity sufficient to explain cellular H₂ production levels, and this seems to eliminate the need for a soluble hydrogen production activity and therefore leave the soluble hydrogenase without a physiological function. Therefore, the steady-state kinetics of the soluble hydrogenase were reinvestigated. In contrast to previous reports, a low K_m for H₂ (~20 μM) was found, which suggests a relatively high affinity for hydrogen. Also, the hydrogen consumption activity was 1 order of magnitude higher than the hydrogen production activity, and CO inhibition was significant (50% inhibition with 20 μM dissolved CO). Since the K_m for NADP⁺ is ~37 μM, we concluded that the soluble hydrogenase from P. furiosus is likely to function in the regeneration of NADPH and thus reuses the hydrogen produced by the membrane-bound hydrogenase in proton respiration.