Center of pressure motion after calf vibration is more random in fallers than non-fallers: Prospective study of older individuals

Aging is associated with changes in balance control and elderly take longer to adapt to changing sensory conditions, which may increase falls risk. Low amplitude calf muscle vibration stimulates local sensory afferents/receptors and affects sense of upright when applied in stance. It has been used to assess the extent the nervous system relies on calf muscle somatosensory information and to rapidly change/perturb part of the somatosensory information causing balance unsteadiness by addition and removal of the vibratory stimulus. This study assessed the effect of addition and removal of calf vibration on balance control (in the absence of vision) in elderly individuals (> 65 years, n = 99) who did (n = 41) or did not prospectively report falls (n = 58), and in a group of young individuals (18-25 years, n = 23). Participants stood barefoot and blindfolded on a force plate for 135 s. Vibrators (60 Hz, 1 mm) attached bilaterally over the triceps surae muscles were activated twice for 15 s; after 15 and 75 s (45 s for recovery). Balance measures were applied in a windowed (15 s epoch) manner to compare center-of-pressure (CoP) motion before, during and after removal of calf vibration between groups. In each epoch, CoP motion was quantified using linear measures, and non-linear measures to assess temporal structure of CoP motion [using recurrence quantification analysis (RQA) and detrended fluctuation analysis]. Mean CoP displacement during and after vibration did not differ between groups, which suggests that calf proprioception and/or weighting assigned by the nervous system to calf proprioception was similar for the young and both groups of older individuals. Overall, compared to the elderly, CoP motion of young was more predictable and persistent. Balance measures were not different between fallers and non-fallers before and during vibration. However, non-linear aspects of CoP motion of fallers and non-fallers differed after removal of vibration, when dynamic re-weighting is required. During this period fallers exhibited more random CoP motion, which could result from a reduced ability to control balance and/or a reduced ability to dynamically reweight proprioceptive information. These results show that non-linear measures of balance provide evidence for deficits in balance control in people who go on to fall in the following 12 months

Increased duration of co-contraction of medial knee muscles is associated with greater progression of knee osteoarthritis

Background: As knee osteoarthritis (OA) cannot be cured, treatments that slow structural disease progression are a priority. Knee muscle activation has a potential role in OA pathogenesis. Although enhanced knee muscle co-contraction augments joint stability; this may speed structural disease progression by increased joint load. Objective: This study investigated the relationship between cartilage loss and duration of co-contraction of medial/lateral knee muscles in medial knee OA. Design: Prospective cohort study. Methods: Medial (vastus medialis; semimembranosus) and lateral (vastus lateralis; biceps femoris) knee muscle myoelectric activity was recorded in 50 people with medial knee OA during natural speed walking at baseline. Medial tibial cartilage volume was measured from MRI at baseline and 12 months. Relationships between percent volume loss and duration of co-contraction of medial/lateral muscles around stance phase and ratio of duration of medial to lateral muscle co-contraction were evaluated with multiple linear regression. Results: Greater duration of medial muscle co-contraction and greater duration of medial relative to lateral co-contraction correlated positively with annual percent loss of medial tibial cartilage volume (. P = 0.003). Estimated cartilage loss was 0.14 (95% confidence interval -0.23 to -0.05) greater for each increase in medial muscle co-contraction duration of 1% of the gait cycle. Lateral muscle co-contraction inversely correlated with cartilage loss. Conclusion: Data support the hypothesis that augmented medial knee muscle co-contraction underpins faster progression of medial knee OA. Increased duration of lateral muscle co-contraction protected against medial cartilage loss. Exercise and biomechanical interventions to change knee muscle activation patterns provide possible candidates to slow progression of knee OA

A promiscuous archaeal cardiolipin synthase enables construction of diverse natural and unnatural phospholipids

Cardiolipins (CL) are a class of lipids involved in the structural organization of membranes, enzyme functioning, and osmoregulation. Biosynthesis of CLs has been studied in eukaryotes and bacteria, but has been barely explored in archaea. Unlike the common fatty acyl chain-based ester phospholipids, archaeal membranes are made up of the structurally different isoprenoid-based ether phospholipids, possibly involving a different cardiolipin biosynthesis mechanism. Here, we identified a phospholipase D motif-containing cardiolipin synthase (MhCls) from the methanogen Methanospirillum hungatei. The enzyme was overexpressed in Escherichia coli, purified, and its activity was characterized by LC-MS analysis of substrates/products. MhCls utilizes two archaetidylglycerol (AG) molecules in a transesterification reaction to synthesize glycerol-di-archaetidyl-cardiolipin (Gro-DACL) and glycerol. The enzyme is non-selective to the stereochemistry of the glycerol-backbone and the nature of the lipid tail, as it also accepts phosphatidylglycerol (PG) to generate glycerol-di-phosphatidyl-cardiolipin (Gro-DPCL). Remarkably, in the presence of AG and PG, MhCls formed glycerol-archaetidyl-phosphatidyl-cardiolipin (Gro-APCL), an archaeal-bacterial hybrid cardiolipin species that so far has not been observed in nature. Due to the reversibility of the transesterification, in the presence of glycerol, Gro-DPCL can be converted back into two PG molecules. In the presence of other compounds that contain primary hydroxyl groups (e.g., alcohols, water, sugars), various natural and unique unnatural phospholipid species could be synthesized, including multiple di-phosphatidyl-cardiolipin species. Moreover, MhCls can utilize a glycolipid in the presence of phosphatidylglycerol to form a glycosyl-mono-phosphatidyl-cardiolipin species, emphasizing the promiscuity of this cardiolipin synthase, that could be of interest for bio-catalytic purposes

Redox properties of the iron-sulfur clusters in activated Fe-hydrogenase from Desulfovibrio vulgaris (Hildenborough)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65750/1/j.1432-1033.1992.tb17261.x.pd

Refashioning the Ethiopian monarchy in the twentieth century: An intellectual history

This article traces the shift in the Ethiopian monarchical ideology from lineage as symbolic Christian filiation to dynasty as a political genealogy of sovereign power. From the end of the nineteenth century, and more prominently under Haylä Səllase, Ethiopian state sources started qualifying the Ethiopian ruling dynasty as ‘unbroken’ in history. A record of ‘uninterrupted’ power allowed the Ethiopian government to politically appropriate past glories and claim them as ‘ours’, thus compensating for the political weakness of the present with the political greatness of the past. The ideological rebranding of the Ethiopian monarchy in the 1930s brought Ethiopia closer to Japan, and the ‘eternalist clause’ of the Meiji constitution offered a powerful model of how to recodify dynasty in modern legal terms. An intellectual history of dynasty in the Ethiopian context sees the concept simultaneously associated with both hegemonic and counter-hegemonic political projects. The narratives of continuity enabled by the dynastisation of history were successful in invigorating the pro-Ethiopian front during the Italian occupation of Ethiopia (1936-1941), but served at the same time to reinforce domestic mechanisms of class, political and cultural domination

Granville Wolbert Papers, 1951-1952

Includes a series of letters to Roy P. Johnson of the Fargo Forum newspaper regarding his life in North Dakota. Includes 9 pages of excerpts from an autobiographical manuscript by Wolbert, in which he details his business and political careers in N.D. Includes mention of living in Fargo, N.D., being in the train that overturned at Fargo during the 1890 tornado, serving in the N.D. legislature, Judson LaMoure, Alexander McKenzie, Tom Hall and others