Trabecular bone score is associated with volumetric bone density and microarchitecture as assessed by central QCT and HRpQCT in Chinese American and white women.

Although high-resolution peripheral quantitative computed tomography (HRpQCT) and central quantitative computed tomography (QCT) studies have shown bone structural differences between Chinese American (CH) and white (WH) women, these techniques are not readily available in the clinical setting. The trabecular bone score (TBS) estimates trabecular microarchitecture from dual-energy X-ray absorptiometry spine images. We assessed TBS in CH and WH women and investigated whether TBS is associated with QCT and HRpQCT indices. Areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry, lumbar spine (LS) TBS, QCT of the LS and hip, and HRpQCT of the radius and tibia were performed in 71 pre- (37 WH and 34 CH) and 44 postmenopausal (21 WH and 23 CH) women. TBS did not differ by race in either pre- or postmenopausal women. In the entire cohort, TBS positively correlated with LS trabecular volumetric bone mineral density (vBMD) (r = 0.664), femoral neck integral (r = 0.651), trabecular (r = 0.641) and cortical vBMD (r = 0.346), and cortical thickness (C/I; r = 0.540) by QCT (p < 0.001 for all). TBS also correlated with integral (r = 0.643), trabecular (r = 0.574) and cortical vBMD (r = 0.491), and C/I (r = 0.541) at the total hip (p < 0.001 for all). The combination of TBS and LS aBMD predicted more of the variance in QCT measures than aBMD alone. TBS was associated with all HRpQCT indices (r = 0.20-0.52) except radial cortical thickness and tibial trabecular thickness. Significant associations between TBS and measures of HRpQCT and QCT in WH and CH pre- and postmenopausal women demonstrated here suggest that TBS may be a useful adjunct to aBMD for assessing bone quality.

Testosterone: a specific competitive antagonist of aldosterone in the toad bladder.

Testosterone (100 nM to 40 microM) antagonized the effect of aldosterone (10 nM) on Na+ transport in the toad bladder measured in vitro as short-circuit current (SCC). Half-maximal inhibition occurred at an antagonist-agonist molar ratio of 150:1. The antagonist action of testosterone was reversed by addition of more aldosterone. The antagonism was specific in the sense that testosterone (20 microM) did not inhibit the response of the SCC to oxytocin (50 mU/ml). By itself, testosterone (up to 20 microM) had no agonist activity on base-line SCC. Finally, testosterone (500 nM to 20 microM) specifically displaced [3H]aldosterone (5 nm) from its cytoplasmic and nuclear binding sites in bladders incubated in vitro at 25 or 0 degrees C and labeled at steady state. There was a significant linear correlation between the effect of testosterone on the aldosterone-dependent SCC and its effect on [3H]aldosterone binding sites in the cytoplasm and in the nucleus. We conclude that 1) testosterone is a specific competitive antagonist of aldosterone, and 2) [3H]aldosterone nuclear and cytoplasmic binding sites could be mineralocorticoid receptors, mediating the action of aldosterone on Na+ transport.

Femoroacetabular impingement: normal values of the quantitative morphometric parameters in asymptomatic hips.

OBJECTIVE: To determine the means and the reference intervals of the quantitative morphometric parameters of femoroacetabular impingement (FAI) in normal hips with high-resolution computed tomography (CT). METHODS: We prospectively included 94 adult individuals who underwent CT for thoracic, abdominal or urologic pathologies. Patients with a clinical history of hip pathology and/or with osteoarthritis on CT were excluded. We calculated means and 95 % reference intervals for imaging signs of cam-type (alpha angle at 90° and 45° and femoral head-neck offset) and pincer-type impingement (acetabular version angle, lateral centre-edge angle and acetabular index). RESULTS: The 95 % reference interval limits were all far beyond the abnormal thresholds found in the literature for cam-type and to a lesser extent for pincer-type FAI. The upper limits of the reference intervals for the alpha angles (at 90°/45°) were 68°/83° (men) and 69°/84° (women), compared to thresholds from the literature (50°, 55° or 60°). Reference intervals were similar between genders for cam-type parameters, and slightly differed for pincer-type. CONCLUSION: The 95 % reference intervals of morphometric measurements of FAI in asymptomatic hips were beyond the abnormal thresholds, which was especially true for cam-type FAI. Our results suggest the need for redefining the current morphometric parameters used in the diagnosis of FAI. KEY POINTS: ? 95 % reference intervals limits of FAI morphotype were beyond currently defined thresholds. ? Reference intervals of pincer-type morphotype measurements were close to current definitions. ? Reference intervals of cam-type morphotype measurements were far beyond the current definitions. ? Current morphometric definitions of cam-type morphotype should be used with care.

Effects of mineralocorticoid and K+ concentration on K+ secretion and ROMK channel expression in a mouse cortical collecting duct cell line.

The cortical collecting duct (CCD) plays a key role in regulated K(+) secretion, which is mediated mainly through renal outer medullary K(+) (ROMK) channels located in the apical membrane. However, the mechanisms of the regulation of urinary K(+) excretion with regard to K(+) balance are not well known. We took advantage of a recently established mouse CCD cell line (mCCD(cl1)) to investigate the regulation of K(+) secretion by mineralocorticoid and K(+) concentration. We show that this cell line expresses ROMK mRNA and a barium-sensitive K(+) conductance in its apical membrane. As this conductance is sensitive to tertiapin-Q, with an apparent affinity of 6 nM, and to intracellular acidification, it is probably mediated by ROMK. Overnight exposure to 100 nM aldosterone did not significantly change the K(+) conductance, while it increased the amiloride-sensitive Na(+) transport. Overnight exposure to a high K(+) (7 mM) concentration produced a small but significant increase in the apical membrane barium-sensitive K(+) conductance. The mRNA levels of all ROMK isoforms measured by qRT-PCR were not changed by altering the basolateral K(+) concentration but were decreased by 15-45% upon treatment with aldosterone (0.3 or 300 nM for 1 and 3 h). The paradoxical response of ROMK expression to aldosterone could possibly work as a preventative mechanism to avoid excessive K(+) loss which would otherwise result from the increased electrogenic Na(+) transport and associated depolarization of the apical membrane in the CCD. In conclusion, mCCD(cl1) cells demonstrate a significant K(+) secretion, probably mediated by ROMK, which is not stimulated by aldosterone but increased by overnight exposure to a high K(+) concentration.

Amiloride-sensitive epithelial Na+ channel is made of three homologous subunits.

The amiloride-sensitive epithelial sodium channel constitutes the rate-limiting step for sodium reabsorption in epithelial cells that line the distal part of the renal tubule, the distal colon, the duct of several exocrine glands, and the lung. The activity of this channel is upregulated by vasopressin and aldosterone, hormones involved in the maintenance of sodium balance, blood volume and blood pressure. We have identified the primary structure of the alpha-subunit of the rat epithelial sodium channel by expression cloning in Xenopus laevis oocytes. An identical subunit has recently been reported. Here we identify two other subunits (beta and gamma) by functional complementation of the alpha-subunit of the rat epithelial Na+ channel. The ion-selective permeability, the gating properties and the pharmacological profile of the channel formed by coexpressing the three subunits in oocytes are similar to that of the native channel.

Comparative phylogeography of mutualists and the effect of the host on the genetic structure of its partners.

Whether or not species participating in specialized and obligate interactions display similar and simultaneous demographic variations at the intraspecific level remains an open question in phylogeography. In the present study, we used the mutualistic nursery pollination occurring between the European globeflower Trollius europaeus and its specialized pollinators in the genus Chiastocheta as a case study. Explicitly, we investigated if the phylogeographies of the pollinating flies are significantly different from the expectation under a scenario of plant-insect congruence. Based on a large-scale sampling, we first used mitochondrial data to infer the phylogeographical histories of each fly species. Then, we defined phylogeographical scenarios of congruence with the plant history, and used maximum likelihood and Bayesian approaches to test for plant-insect phylogeographical congruence for the three Chiastocheta species. We show that the phylogeographical histories of the three fly species differ. Only Chiastocheta lophota and Chiastocheta dentifera display strong spatial genetic structures, which do not appear to be statistically different from those expected under scenarios of phylogeographical congruence with the plant. The results of the present study indicate that the fly species responded in independent and different ways to shared evolutionary forces, displaying varying levels of congruence with the plant genetic structure

cAMP-dependent chloride secretion mediates tubule enlargement and cyst formation by cultured mammalian collecting duct cells.

Polycystic kidney diseases result from disruption of the genetically defined program that controls the size and geometry of renal tubules. Cysts which frequently arise from the collecting duct (CD) result from cell proliferation and fluid secretion. From mCCD(cl1) cells, a differentiated mouse CD cell line, we isolated a clonal subpopulation (mCCD-N21) that retains morphogenetic capacity. When grown in three-dimensional gels, mCCD-N21 cells formed highly organized tubular structures consisting of a palisade of polarized epithelial cells surrounding a cylindrical lumen. Subsequent addition of cAMP-elevating agents (forskolin or cholera toxin) or of membrane-permeable cAMP analogs (CPT-cAMP) resulted in rapid and progressive dilatation of existing tubules, leading to the formation of cystlike structures. When grown on filters, mCCD-N21 cells exhibited a high transepithelial resistance as well as aldosterone- and/or vasopressin-induced amiloride-sensitive and -insensitive current. The latter was in part inhibited by Na(+)-K(+)-2Cl(-) cotransporter (bumetanide) and chloride channel (NPPB) inhibitors. Real-time PCR analysis confirmed the expression of NKCC1, the ubiquitous Na(+)-K(+)-2Cl(-) cotransporter and cystic fibrosis transmembrane regulator (CFTR) in mCCD-N21 cells. Tubule enlargement and cyst formation were prevented by inhibitors of Na(+)-K(+)-2Cl(-) cotransporters (bumetanide or ethacrynic acid) or CFTR (NPPB or CFTR inhibitor-172). These results further support the notion that cAMP signaling plays a key role in renal cyst formation, at least in part by promoting chloride-driven fluid secretion. This new in vitro model of tubule-to-cyst conversion affords a unique opportunity for investigating the molecular mechanisms that govern the architecture of epithelial tubes, as well as for dissecting the pathophysiological processes underlying cystic kidney diseases.

Respective roles of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMP) in cell surface expression of CRLR/RAMP heterodimeric receptors.

Receptor activity modifying proteins RAMP1, RAMP2, and RAMP3 are responsible for defining affinity to ligands of the calcitonin receptor-like receptor (CRLR). It has also been proposed that receptor activity-modifying proteins (RAMP) are molecular chaperones required for CRLR transport to the cell surface. Here, we have studied the respective roles of CRLR and RAMP in transporting CRLR/RAMP heterodimers to the plasma membrane by using a highly specific binding assay that allows quantitative detection of cell surface-expressed CRLR or RAMP in the Xenopus oocytes expression system. We show that: (i) heterodimer assembly is not a prerequisite for efficient cell surface expression of CRLR, (ii) N-glycosylated RAMP2 and RAMP3 are expressed at the cell surface and their transport to the plasma membrane requires N-glycans, (iii) RAMP1 is not N-glycosylated and is transported to the plasma membrane only upon formation of heterodimers with CRLR, and (iv) introduction of N-glycosylation sites in the RAMP1 sequence (D58N/G60S, Y71N, and K103N/P105S) allows cell surface expression of these mutants at levels similar to that of wild-type RAMP1 co-expressed with CRLR. Our data argue against a chaperone function for RAMP and identify the role of N-glycosylation in targeting these molecules to the cell surface.

Recurrent deletions and reciprocal duplications of 10q11.21q11.23 including CHAT and SLC18A3 are likely mediated by complex low-copy repeats.

We report 24 unrelated individuals with deletions and 17 additional cases with duplications at 10q11.21q21.1 identified by chromosomal microarray analysis. The rearrangements range in size from 0.3 to 12 Mb. Nineteen of the deletions and eight duplications are flanked by large, directly oriented segmental duplications of >98% sequence identity, suggesting that nonallelic homologous recombination (NAHR) caused these genomic rearrangements. Nine individuals with deletions and five with duplications have additional copy number changes. Detailed clinical evaluation of 20 patients with deletions revealed variable clinical features, with developmental delay (DD) and/or intellectual disability (ID) as the only features common to a majority of individuals. We suggest that some of the other features present in more than one patient with deletion, including hypotonia, sleep apnea, chronic constipation, gastroesophageal and vesicoureteral refluxes, epilepsy, ataxia, dysphagia, nystagmus, and ptosis may result from deletion of the CHAT gene, encoding choline acetyltransferase, and the SLC18A3 gene, mapping in the first intron of CHAT and encoding vesicular acetylcholine transporter. The phenotypic diversity and presence of the deletion in apparently normal carrier parents suggest that subjects carrying 10q11.21q11.23 deletions may exhibit variable phenotypic expressivity and incomplete penetrance influenced by additional genetic and nongenetic modifiers.

Expertises croisées dans la dégénérescence maculaire liée à l'âge. Focus sur la physiopathologie, l'angiogenèse, les données pharmacologiques et cliniques [Review and expert opinion in age related macular degeneration. Focus on the pathophysiology, angiogenesis and pharmacological and clinical data].

Age related macular degeneration (AMD) is a pathological aging of the macula, brought about by the interaction of genetic and environmental factors. It induces geographic atrophy of the retina and/or choroidal neovascularization. In the latter, abnormal vessels develop from the choriocapillaris, with the involvement of VEGF (vascular endothelial growth factor). The VEGF family includes several factors, including VEGF-A, B, C, D, F and PlGF (placental growth factor). Their biological properties and their affinities to the VEGFR1, VEGFR2 and VEGFR3 receptors found on endothelial cells differ. Exudative AMD involves mainly VEGF-A and VEGF-R2. Anti-VEGF agents used in ophthalmology (ranibizumab, bevacizumab and aflibercept) are designed to primarily target this pathway. In vitro, all have sufficient affinity to their ligands. Their therapeutic efficacy must therefore be judged based on clinical criteria. In clinical practice, the minimum number of injections required for a satisfactory result appears to be comparable with all the three. The few available studies on therapeutic substitutions of anti-VEGF compounds suggest that some patients may benefit from substituting the anti-VEGF in cases of an unsatisfactory response to an initial molecule. Although local side effects, including increased risk of geographic atrophy, and systemic effects, including vascular accidents, have been suggested, these risks remain low, specially compared to the benefits of the treatment. Differences in safety between anti-VEGF are theoretically possible but unproven.

Nitric oxide reduces Cl- absorption in the mouse cortical collecting duct through an ENaC-dependent mechanism.

Since nitric oxide (NO) participates in the renal regulation of blood pressure, in part, by modulating transport of Na(+) and Cl(-) in the kidney, we asked whether NO regulates net Cl(-) flux (JCl) in the cortical collecting duct (CCD) and determined the transporter(s) that mediate NO-sensitive Cl(-) absorption. Cl(-) absorption was measured in CCDs perfused in vitro that were taken from aldosterone-treated mice. Administration of an NO donor (10 μM MAHMA NONOate) reduced JCl and transepithelial voltage (VT) both in the presence or absence of angiotensin II. However, reducing endogenous NO production by inhibiting NO synthase (100 μM N(G)-nitro-l-arginine methyl ester) increased JCl only in the presence of angiotensin II, suggesting that angiotensin II stimulates NO synthase activity. To determine the transport process that mediates NO-sensitive changes in JCl, we examined the effect of NO on JCl following either genetic ablation or chemical inhibition of transporters in the CCD. Since the application of hydrochlorothiazide (100 μM) or bafilomycin (5 nM) to the perfusate or ablation of the gene encoding pendrin did not alter NO-sensitive JCl, NO modulates JCl independent of the Na(+)-dependent Cl(-)/HCO3(-) exchanger (NDCBE, Slc4a8), the A cell apical plasma membrane H(+)-ATPase and pendrin. In contrast, both total and NO-sensitive JCl and VT were abolished with application of an epithelial Na(+) channel (ENaC) inhibitor (3 μM benzamil) to the perfusate. We conclude that NO reduces Cl(-) absorption in the CCD through a mechanism that is ENaC-dependent.

Global radiolarian zonation for the Pliensbachian, Toarcian and Aalenian

Jurassic radiolarians from 220 samples in Queen Charlotte Islands, B.C., Williston Lake, B.C., east-central Oregon, Baja California Sur, southern Spain, Austria, Slovenia, Turkey, Oman, Japan and Argentina were studied in order to construct global zonation for the Pliensbachian, Toarcian and Aalenian stages. Well-preserved faunas from continuous stratigraphic sections in Queen Charlotte Islands provide the most detailed record for this time interval, and all collections are tied to North American ammonite zones or assemblages. Collections from nearly all other areas lack independent dating except for early Toarcian carbon-isotope dating in Slovenia and late Aalenian ammonites in Spain. A database of 197 widely distributed updated taxonomic species was used to construct a Unitary Association (UA) zonation for the interval. A global sequence of 41 UAs was obtained for the top of the Sinemurian to the base of the Bajocian. The first and the last UAs represent the Late Sinemurian and the Early Bajocian respectively. The remaining 39 UAs were merged into nine zones (four Early Pliensbachian, one Late Pliensbachian, one Early Toarcian, one Middle-Late Toarcian, and two Aalenian) according to prominent radiolarian faunal breaks and ammonite data. The new zones are the Canutus tip pen - Katroma clara Zone (latest Sinemurian/earliest Pliensbachian); Zartus mostleri - Pseudoristola megaglobosa, Hsuum mulleri - Trillus elkhornensis and Gigi fustis - Lantus sixi zones (Early Pliensbachian); Eucyrtidiellum nagaiae - Praeparvicingula tlellensis Zone (Late Pliensbachian); Napora relica - Eucyrtidiellum disparile Zone (Early Toarcian); Elodium pessagnoi - Hexasaturnalis hexagonus Zone (Middle and Late Toarcian); Higumastra transversa - Napora nipponica Zone (early Aalenian); and Mirifusus proavus - Transhsuum hisuikyoense Zone (late Aalenian). These zones can be correlated worldwide and link previously established UA zonations for the Hettangian-Sinemurian and the Middle to Upper Jurassic. The new zonation allows high-resolution dating in the studied interval and provides a solid basis for analyzing faunal turnovers and the paleobiogeography of Jurassic radiolarians. (C) 2010 Elsevier B.V. All rights reserved.

D6PK AGCVIII Kinases Are Required for Auxin Transport and Phototropic Hypocotyl Bending in Arabidopsis.

Phototropic hypocotyl bending in response to blue light excitation is an important adaptive process that helps plants to optimize their exposure to light. In Arabidopsis thaliana, phototropic hypocotyl bending is initiated by the blue light receptors and protein kinases phototropin1 (phot1) and phot2. Phototropic responses also require auxin transport and were shown to be partially compromised in mutants of the PIN-FORMED (PIN) auxin efflux facilitators. We previously described the D6 PROTEIN KINASE (D6PK) subfamily of AGCVIII kinases, which we proposed to directly regulate PIN-mediated auxin transport. Here, we show that phototropic hypocotyl bending is strongly dependent on the activity of D6PKs and the PIN proteins PIN3, PIN4, and PIN7. While early blue light and phot-dependent signaling events are not affected by the loss of D6PKs, we detect a gradual loss of PIN3 phosphorylation in d6pk mutants of increasing complexity that is most severe in the d6pk d6pkl1 d6pkl2 d6pkl3 quadruple mutant. This is accompanied by a reduction of basipetal auxin transport in the hypocotyls of d6pk as well as in pin mutants. Based on our data, we propose that D6PK-dependent PIN regulation promotes auxin transport and that auxin transport in the hypocotyl is a prerequisite for phot1-dependent hypocotyl bending.

ENaC inhibition stimulates Cl- secretion in the mouse cortical collecting duct through an NKCC1-dependent mechanism.

In cortical collecting ducts (CCDs) perfused in vitro, inhibiting the epithelial Na(+) channel (ENaC) reduces Cl(-) absorption. Since ENaC does not transport Cl(-), the purpose of this study was to determine how ENaC modulates Cl(-) absorption. Thus, Cl(-) absorption was measured in CCDs perfused in vitro that were taken from mice given aldosterone for 7 days. In wild-type mice, we observed no effect of luminal hydrochlorothiazide on either Cl(-) absorption or transepithelial voltage (V(T)). However, application of an ENaC inhibitor [benzamil (3 μM)] to the luminal fluid or application of a Na(+)-K(+)-ATPase inhibitor to the bath reduced Cl(-) absorption by ∼66-75% and nearly obliterated lumen-negative V(T). In contrast, ENaC inhibition had no effect in CCDs from collecting duct-specific ENaC-null mice (Hoxb7:CRE, Scnn1a(loxlox)). Whereas benzamil-sensitive Cl(-) absorption did not depend on CFTR, application of a Na(+)-K(+)-2Cl(-) cotransport inhibitor (bumetanide) to the bath or ablation of the gene encoding Na(+)-K(+)-2Cl(-) cotransporter 1 (NKCC1) blunted benzamil-sensitive Cl(-) absorption, although the benzamil-sensitive component of V(T) was unaffected. In conclusion, first, in CCDs from aldosterone-treated mice, most Cl(-) absorption is benzamil sensitive, whereas thiazide-sensitive Cl(-) absorption is undetectable. Second, benzamil-sensitive Cl(-) absorption occurs by inhibition of ENaC, possibly due to elimination of lumen-negative V(T). Finally, benzamil-sensitive Cl(-) flux occurs, at least in part, through transcellular transport through a pathway that depends on NKCC1.

Biodiversity study of arthropods collected on rat carrion in Yaounde, Cameroon: first study on forensic entomology in Central Africa

The first investigation of arthropods associated with carrion in Cameroon was carried out within the campus of the University of Yaounde I (Cameroon) from 17thJanuary to 3rd April 2008. Carcasses of rats (Rattus norvegicus Berkenhout, 1769 var WISTAR) were exposed to colonization by the local fauna of arthropods. The invading organisms were collected daily during the study period. 2287 individuals of arthropod belonging to 3 classes, 16 orders, 37 families and 7 subfamilies were identified. The insects assessed were mainly Diptera, Coleoptera and Acari. This study illustrates the high diversity of the necroentomofauna in Cameroon and provides an insight approximation into the succession pattern of invading insect and a weekly estimation of the time of death.