Altered postural modulation of Hoffmann reflex in the soleus and fibularis longus associated with chronic ankle instability

Our purpose was to assess Hoffmann (H) reflex modulations of the soleus and fibularis longus in three body positions (prone, bipedal and unipedal stances) in subjects with and without chronic ankle instability (CAI). Sixteen subjects with unilateral CAI and 15 healthy controls participated. Maximum H-reflexes and motor (M) waves were recorded bilaterally from the soleus and fibularis longus while subjects lied prone and then stood in quiet bipedal and unipedal stances. Maximum H-reflexes were normalized to maximum M waves to obtain H_max:M_max ratios for the three positions. H-reflex modulations, for each muscle, were quantified as the percent change scores in H_max:M_max ratios between each pair of positions: prone to bipedal, bipedal to unipedal, and prone to unipedal. There were significant group by limb interactions found for all three modulations (P < 0.05) for the soleus. In the CAI group, soleus modulations in involved limbs were significantly lower than in uninvolved limbs and both limbs in the controls. For the fibularis longus, similar results were found for the bipedal to unipedal and prone to unipedal modulations. Constrained ability of the sensorimotor system to down regulate H-reflex in more demanding postures may represent a potential mechanism of postural control deficits associated with CAI.     

The role and pathophysiological relevance of membrane transporter PepT1 in intestinal inflammation and inflammatory bowel disease

Intestinal inflammation is characterized by epithelial disruption, leading to loss of barrier function and the recruitment of immune cells, including neutrophils. Although the mechanisms are not yet completely understood, interactions between environmental and immunological factors are thought to be critical in the initiation and progression of intestinal inflammation. In recent years, it has become apparent that the di/tripeptide transporter PepT1 may play an important role in the pathogenesis of such inflammation. In healthy individuals, PepT1 is primarily expressed in the small intestine and transports di/tripeptides for metabolic purposes. However, during chronic inflammation such as that associated with inflammatory bowel disease, PepT1 expression is upregulated in the colon, wherein the protein is normally expressed either minimally or not at all. Several recent studies have shown that PepT1 binds to and transports various bacterial di/tripeptides into colon cells, leading to activation of downstream proinflammatory responses via peptide interactions with innate immune receptors. In the present review, we examine the relationship between colonic PepT1-mediated peptide transport in the colon and activation of innate immune responses during disease. It is important to understand the mechanisms of PepT1 action during chronic intestinal inflammation to develop future therapies addressing inappropriate immune activation in the colon.     

Analysis of candidate genes on chromosome 2 in oral cleft case-parent trios from three populations

Isolated oral clefts, including cleft lip with/without cleft palate (CL/P) and cleft palate (CP), have a complex and heterogeneous etiology. Case-parent trios from three populations were used to study genes spanning chromosome 2, where single nucleotide polymorphic (SNP) markers were analyzed individually and as haplotypes. Case-parent trios from three populations (74 from Maryland, 64 from Singapore and 95 from Taiwan) were genotyped for 962 SNPs in 104 genes on chromosome 2, including two well-recognized candidate genes: TGFA and SATB2. Individual SNPs and haplotypes (in sliding windows of 2–5 SNPs) were used to test for linkage and disequilibrium separately in CL/P and CP trios. A novel candidate gene (ZNF533) showed consistent evidence of linkage and disequilibrium in all three populations for both CL/P and CP. SNPs in key regions of ZNF533 showed considerable variability in estimated genotypic odds ratios and their significance, suggesting allelic heterogeneity. Haplotype frequencies for regions of ZNF533 were estimated and used to partition genetic variance into among-and within-population components. Wright’s fixation index, a measure of genetic diversity, showed little difference between Singapore and Taiwan compared with Maryland. The tensin-1 gene (TNS1) also showed evidence of linkage and disequilibrium among both CL/P and CP trios in all three populations, albeit at a lower level of significance. Additional genes (VAX2, GLI2, ZHFX1B on 2p; WNT6–WNT10A and COL4A3–COL4A4 on 2q) showed consistent evidence of linkage and disequilibrium only among CL/P trios in all three populations, and TGFA showed significant evidence in two of three populations.Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Jogging gait kinetics following fatiguing lumbar paraspinal exercise

A relationship exists between lumbar paraspinal muscle fatigue and quadriceps muscle activation. The objective of this study was to determine whether hip and knee joint moments during jogging changed following paraspinal fatiguing exercise. Fifty total subjects (25 with self-reported history of low back pain) performed fatiguing, isometric lumbar extension exercise until a shift in EMG median frequency corresponding to a mild level of muscle fatigue was observed. We compared 3-dimensional external joint moments of the hip and knee during jogging before and after lumbar paraspinal fatigue using a 10-camera motion analysis system. Reduced external knee flexion, knee adduction, knee internal rotation and hip external rotation moments and increased external knee extension moments resulted from repetitive lumbar paraspinal fatiguing exercise. Persons with a self-reported history of LBP had larger knee flexion moments than controls during jogging. Neuromuscular changes in the lower extremity occur while resisting knee and hip joint moments following isolated lumbar paraspinal exercise. Persons with a history of LBP seem to rely more heavily on quadriceps activity while jogging.     

Developmental characterization of the gene for laminin alpha-chain in sea urchin embryos.

We describe the isolation and characterization of a cDNA clone encoding a region of the carboxy terminal globular domain (G domain) of the alpha-1 chain of laminin from the sea urchin, Strongylocentrotus purpuratus. Sequence analysis indicates that the 1.3 kb cDNA (spLAM-alpha) encodes the complete G2 and G3 subdomains of sea urchin a-laminin. The 11 kb spLAM-alpha mRNA is present in the egg and declines slightly in abundance during development to the pluteus larva. The spLAM-alpha gene is also expressed in a variety of adult tissues. Whole mount in situ hybridization of gastrula stage embryos indicates that ectodermal and endodermal epithelia and mesenchyme cells contain the spLAM-alpha mRNA. Immunoprecipitation experiments using an antibody made to a recombinant fusion protein indicates spLAM-alpha protein is synthesized continuously from fertilization as a 420 kDa protein which accumulates from low levels in the egg to elevated levels in the pluteus larva. Light and electron microscopy identify spLAM-alpha as a component of the basal lamina. Blastocoelic microinjection of an antibody to recombinant spLAM-alpha perturbs gastrulation and skeleton formation by primary mesenchyme cells suggesting an important role for laminin in endodermal and mesodermal morphogenesis.     

Scale diversity in bigeye tuna (Thunnus obesus): Fat‐filled trabecular scales made of cellular bone

Tunas of the genus Thunnus possess many morphological and physiological adaptations for their high‐performance epipelagic ecology. Although Thunnus anatomy has been studied, there are no quantitative studies on the structure of their scales. We investigated the scales of bigeye tuna (Thunnus obesus) from ten regions of the body using micro computed tomography (µCT)‐scanning and histology to quantitatively and qualitatively compare regional scale morphology. We found a diversity of scale sizes and shapes across the body of bigeye tuna and discriminant function analysis on variables derived from µCT‐data showed that scales across the body differ quantitatively in shape and size. We also report the discovery of a novel scale type in corselet, tail, and cheek regions. These modified scales are ossified shells supported by internal trabeculae, filled with fat, and possessing an internal blood supply. Histological analysis showed that the outer lamellar layers of these thickened scales are composed of cellular bone, unexpected for a perciform fish in which bone is typically acellular. In the fairing region of the anterior body, these fat‐filled scales are stacked in layers up to five scales deep, forming a thickened bony casing. Cheek scales also possess a fat‐filled internal trabecular structure, while most posterior body scales are more plate‐like and similar to typical teleost scales. While the function of these novel fat‐filled scales is unknown, we explore several possible hypotheses for their function.     

Ubiquitin-dependent remodeling of the actin cytoskeleton drives cell fusion

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Regional interdependence in calf lungs

We measured K, an index of interdependence in sublobar segments of both intact and excised calf lungs. In excised and intact lungs, segment volume was held constant while the lung was inflated. K in excised lungs was of small magnitude but was greater in caudal than in cranial and middle lobes. When isolated segments in a variety of regions and with a variety of shapes were studied, K was positively correlated with the interface area between the segment and the remainder of the lung, was negatively correlated with the pleural surface area of the segment, but was not correlated with segment volume. In a given region of lung, however, small segments had a greater interdependence than large segments. In intact lungs of anesthetized calves, K was an order of magnitude greater than in excised lungs, confirming that the chest wall is the major determinant of interdependence. There were no lobar differences in K in intact lungs.