Depletion of ceramides with very long chain fatty acids causes defective skin permeability barrier function, and neonatal lethality in ELOVL4 deficient mice

Very long chain fatty acids (VLCFA), either free or as components of glycerolipids and sphingolipids, are present in many organs. Elongation of very long chain fatty acids-4 (ELOVL4) belongs to a family of 6 members of putative fatty acid elongases that are involved in the formation of VLCFA. Mutations in ELOVL4 were found to be responsible for an autosomal dominant form of Stargardt's-like macular dystrophy (STGD3) in human. We have previously disrupted the mouse Elovl4 gene, and found that Elovl4+/- mice were developmentally normal, suggesting that haploinsufficiency of ELOVL4 is not a cause for the juvenile retinal degeneration in STGD3 patients. However, Elovl4-/- mice died within several hours of birth for unknown reason(s). To study functions of ELOVL4 further, we have explored the causes for the postnatal lethality in Elovl4-/- mice. Our data indicated that the mutant mice exhibited reduced thickness of the dermis, delayed differentiation of keratinocytes, and abnormal structure of the stratum corneum. We showed that all Elovl4-/- mice exhibited defective skin water permeability barrier function, leading to the early postnatal death. We further showed that the absence of ELOVL4 results in depletion in the epidermis of ceramides with omega-hydroxy very long chain fatty acids (> or = C28) and accumulation of ceramides with non omega-hydroxy fatty acids of C26, implicating C26 fatty acids as possible substrates of ELOVL4. These data demonstrate that ELOVL4 is required for VLCFA synthesis that is essential for water permeability barrier function of skin.     

LRGUK-1 Is Required for Basal Body and Manchette Function during Spermatogenesis and Male Fertility

Male infertility affects at least 5% of reproductive age males. The most common pathology is a complex presentation of decreased sperm output and abnormal sperm shape and motility referred to as oligoasthenoteratospermia (OAT). For the majority of OAT men a precise diagnosis cannot be provided. Here we demonstrate that leucine-rich repeats and guanylate kinase-domain containing isoform 1 (LRGUK-1) is required for multiple aspects of sperm assembly, including acrosome attachment, sperm head shaping and the initiation of the axoneme growth to form the core of the sperm tail. Specifically, LRGUK-1 is required for basal body attachment to the plasma membrane, the appropriate formation of the sub-distal appendages, the extension of axoneme microtubules and for microtubule movement and organisation within the manchette. Manchette dysfunction leads to abnormal sperm head shaping. Several of these functions may be achieved in association with the LRGUK-1 binding partner HOOK2. Collectively, these data establish LRGUK-1 as a major determinant of microtubule structure within the male germ line.     

A comparison of EMG feedback and alternative anxiety treatment programs

Four cohorts of 40 subjects each were randomly assigned to 1 of 10 treatment conditions utilizing EMG feedback, cognitive monitoring training, systematic desensitization, high expectancy discussion group, or waiting list controls either in isolation or in various combinations. A three-way ANOVA for repeated measures indicated that significant anxiety reductions were experienced in all noncontrol treatment conditions. Treatment groups employing EMG feedback demonstrated significantly greater anxiety decrements on Cattell's IPAT Self-Analysis Form, and baseline frontalis EMG. Adding desensitization or cognitive monitoring to EMG feedback did not produce a more powerful effect than using EMG feedback alone. Sex and age differences were also observed. Some implications are discussed.This research was supported in part by a grant from the Medical Services Research Foundation of Alberta.     

Interaction of chiral MS-245 analogs at h5-HT6 receptors

Optically active pyrrolidinylmethylindole analogs related in structure to the benzenesulfonyltryptamine 5-HT(6) receptor antagonist MS-245 were evaluated and their R-isomers were found to bind with affinity higher than their S-enantiomers.     

Differences in Chain Usage and Cross-linking Specificities of Cartilage Type V/XI Collagen Isoforms with Age and Tissue

Collagen type V/XI is a minor but essential component of collagen fibrils in vertebrates. We here report on age- and tissue-related variations in isoform usage in cartilages. With maturation of articular cartilage, the α1(V) chain progressively replaced the α2(XI) chain. A mix of the molecular isoforms, α1(XI)α1(V)α3(XI) and α1(XI)α2(XI)α3(XI), best explained this finding. A prominence of α1(V) chains is therefore characteristic and a potential biomarker of mature mammalian articular cartilage. Analysis of cross-linked peptides showed that the α1(V) chains were primarily cross-linked to α1(XI) chains in the tissue and hence an integral component of the V/XI polymer. From nucleus pulposus of the intervertebral disc (in which the bulk collagen monomer is type II as in articular cartilage), type V/XI collagen consisted of a mix of five genetically distinct chains, α1(XI), α2(XI), α3(XI), α1(V), and α2(V). These presumably were derived from several different molecular isoforms, including α1(XI)α2(XI)α3(XI), (α1(XI))₂α2(V), and others. Meniscal fibrocartilage shows yet another V/XI phenotype. The findings support and extend the concept that the clade B subfamily of COL5 and COL11 gene products should be considered members of the same collagen subfamily, from which, in combination with clade A gene products (COL2A1 or COL5A2), a range of molecular isoforms has evolved into tissue-dependent usage. We propose an evolving role for collagen V/XI isoforms as an adaptable polymeric template of fibril macro-architecture.The collagen framework of hyaline cartilages is based on a covalently cross-linked heteropolymeric network of types II, IX, and XI collagens. During development, collagen type IX molecules are covalently linked to the surface of thin, new fibrils of type II collagen polymerized on a template of type XI collagen (1–5). In fetal cartilage, type XI collagen is a heterotrimer of three genetically distinct chains, α1(XI), α2(XI), and α3(XI) in a 1:1:1 ratio (6–9). The α3(XI) chain has the same primary sequence as α1(II), but the chains differ in their post-translational processing and cross-linking properties (7–9). All three collagen subunits, II, IX, and XI, are heavily cross-linked in the same fibril through a lysyl oxidase-mediated mechanism (2, 5, 9). The location of the cross-links determined by sequence analysis of peptides prepared from proteolytically degraded fibrils reveals a high degree of chain specificity (9). Collagen XI molecules are linked to each other in a head-to-tail fashion by N-telopeptide² to helix cross-links and laterally to type II collagen molecules through α1(II) C-telopeptides (9). Isolated from mature articular cartilage, type XI collagen includes a significant pool of α1(V) chains (6), implying the presence of V/XI hybrid molecules. The ratio of type XI collagen to type II collagen is about 1 to 10 in fetal bovine and human epiphyseal cartilage when compared with 1 to 30 in adult articular cartilage. Similarly, the ratio of collagen IX to collagen II falls from about 1 to 10 to 1 to 100 between fetal and adult. In adult articular cartilage, most of the collagen IX is located in the immediate pericellular matrix (10–12).The intervertebral disc has a unique collagen architecture that combines features of ligament and cartilage in its morphology, function, and matrix biochemistry. The lamellar fabric of the outer annulus fibrosus combines collagens I and II fibrils in a complex weave with a radial gradient from mostly type I in the outermost layers and mostly type II in the interior. Nucleus pulposus, the gel-like center of the young intervertebral disc, has a similar collagen molecular phenotype to hyaline cartilage in which types II, IX, and XI collagens are the principal cross-linked fibrillar components (13–16). Collagen IX in the disc has a different protein isoform to that of hyaline cartilages. The α1(IX) chain is expressed as a short form that lacks the amino-terminal NC4 domain (16). One of the aims of the present study was to determine whether a unique pattern of type V/XI hybrid molecules is present in disc tissue when compared with articular cartilage and a more typical fibrocartilage, the knee meniscus.The results show an accumulation of collagen α1(V) chains as articular cartilage matures. A related but distinct complexity in chain usage in the type V/XI collagen of nucleus pulposus is also revealed. Such tissue diversity suggests that the different molecular isoforms produce functional differences in the type V/XI polymeric template on which the bulk fibril architecture of a tissue is built.     

ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion--Part II: shoulder, elbow, wrist and hand

In this communication, the Standardization and Terminology Committee (STC) of the International Society of Biomechanics proposes a definition of a joint coordinate system (JCS) for the shoulder, elbow, wrist, and hand. For each joint, a standard for the local axis system in each articulating segment or bone is generated. These axes then standardize the JCS. The STC is publishing these recommendations so as to encourage their use, to stimulate feedback and discussion, and to facilitate further revisions. Adopting these standards will lead to better communication among researchers and clinicians.