Lower incidence of fracture after IV bisphosphonates in girls with Rett syndrome and severe bone fragility.

BACKGROUND: Classic Rett Syndrome (RS) is a disabling condition mainly caused by MECP2 mutations. Girls with RS are at risk of developing bone fragility and fractures at a young age which results in pain and may seriously impair quality of life. OBJECTIVE: To retrospectively assess the safety and efficacy of IV bisphosphonates on fracture, bone mineral density (BMD) and bone markers in RS girls with bone fragility. METHODS: RS girls received either IV pamidronate (n = 19) or IV zoledronate (n = 1) for 2 years. RESULTS: Of 20 patients studied (age: 12.5 years [6; 39]), 14 were non-ambulatory. The incidence of fracture decreased from 37 fractures in 20 patients, to 1 fracture during or after treatment (follow-up: 3.1 years [1.5; 5]). The spine BMD Z-score improved from -3.2 [-5.6; -0.1] to -2.2 [-3.8; 0.0], p = 0.0006. Most parents reported decreases in chronic pain and 2 patients started to walk. Urinary calcium excretion decreased from 0.7 [0.18; 1.5] to 0.2 [0.03; 0.67] mM/mM of creatinine (p = 0.0001). Pamidronate was well tolerated. CONCLUSION: RS girls should be screened for impaired bone mineralization and preventive measures should be taken. In girls experiencing fractures, IV bisphosphonates constitute a beneficial adjuvant treatment to diminish the risk of fracture and restore bone density.

Clinical validation of computer-assisted navigation in total hip arthroplasty.

A CT-based navigation system is helpful to evaluate the reamer shaft and the impactor position/orientation during unilateral total hip arthroplasty (THA). The main objective of this study is to determine the accuracy of the Navitrack system by measuring the implant's true anteversion and inclination, based on pre- and postoperative CT scans (n = 9 patients). The secondary objective is to evaluate the clinical validity of measurements based on postop anteroposterior (AP) radiographs for determining the cup orientation. Postop CT-scan reconstructions and postop planar radiographs showed no significant differences in orientation compared to peroperative angles, suggesting a clinical validity of the system. Postoperative AP radiographs normally used in clinic are acceptable to determine the cup orientation, and small angular errors may originate from the patient position on the table.

A bidirectional approach to the synthesis of polypropionates: synthesis of C1-C13 fragment of zincophorin and related isomers.

The structure-activity study of a bioactive natural product containing polypropionate subunits requires that its stereoisomers also be evaluated. Therefore, a general approach to synthesize these motifs is necessary. We describe herein the synthesis of the C1-C13 polypropionate subunit of zincophorin and isomers thereof using a two-reaction sequence: an aldol reaction using a mixture of tetrasubstituted enoxysilanes and a hydrogen-transfer reaction, both under Lewis acid control. Selection of the appropriate Lewis acid dictates the stereochemical outcome of these reactions. From a tactical standpoint, this study shows how a polypropionate sequence can be read and constructed in two directions, either the east-west or the west-east approaches. The choice of the optimal route is influenced by the number of complexation sites that can interfere in the aldol step under bidentate Lewis acid control.

Preserving the superficial branch of the radial nerve during carpometacarpal and metacarpophalangeal joint arthroscopy: an anatomical study.

BACKGROUND: The superficial branch of the radial nerve (SBRN) is potentially at risk during thumb carpometacarpal (TCM) or thumb metacarpophalangeal (TMP) joint arthroscopy. The aim of this anatomical study was to describe the different branching patterns of the SBRN and to optimize positioning of portals during TCM and TMP arthroscopy. METHODS: The SBRN was dissected in 30 forearms. Three branches of the nerve (SR1, SR2, and SR3) were recorded and distances between SBRN branches and portals used for carpometacarpal (TCM) and metacarpophalangeal (TMP) joints of the thumb arthroscopy were measured. Three main portals were used for TCM joint arthroscopy. These portals were an ulnar portal (1-U), a radial portal (1-R), and an accessory portal (D-2). A radial metacarpophalangeal (MCP-rad) and an ulnar metacarpophalangeal (MCP-uln) portal were used for TMP joint arthroscopy. RESULTS: In 24 cases (80%), the 1-R portal was inserted radially (volar) to SR3 at a mean distance of 4.8 mm (0-8). In the remaining six cases (20%) when 1-R portal was inserted ulnar (dorsal) to SR3, the distance was less than 2 mm in all cases. SR3 was always far from the 1-U portal at a mean 13 mm (7-22). The D-2 portal was always close to SR2-D1 at a mean distance of 1.7 mm (0-6). The distance from SR2-D2 and D-2 portal was also inferior by 5 mm. At the level of the metacarphalangeal joint of the thumb, the MCP-rad portal was always situated dorsally and very close to SR3, at a mean distance of 1 mm (0-5). The MCP-uln portal was also situated dorsal to SR2-D1 at a mean distance of 3.7 mm (1.5-6.5). CONCLUSION: The results of this anatomical study confirm actual reported findings about the SR2 and SR3 branches. These two branches of the SBRN are the most at risk of injury during TCM and TMP joint arthroscopy. According to our measurements, the 1-U portal is a safer portal than 1-R and D-2 portal for TCM arthroscopy and should be preferred for surgery necessitating only one portal. Concerning TMP arthroscopy, the SBRN appears less at risk of injury when using a MCP-uln portal and safer than MCP-rad which is at risk at less than 5 mm from the extensor pollicis longus tendon.

The protective role of transferrin in Müller glial cells after iron-induced toxicity.

PURPOSE: Transferrin (Tf) expression is enhanced by aging and inflammation in humans. We investigated the role of transferrin in glial protection. METHODS: We generated transgenic mice (Tg) carrying the complete human transferrin gene on a C57Bl/6J genetic background. We studied human (hTf) and mouse (mTf) transferrin localization in Tg and wild-type (WT) C57Bl/6J mice using immunochemistry with specific antibodies. Müller glial (MG) cells were cultured from explants and characterized using cellular retinaldehyde binding protein (CRALBP) and vimentin antibodies. They were further subcultured for study. We incubated cells with FeCl(3)-nitrilotriacetate to test for the iron-induced stress response; viability was determined by direct counting and measurement of lactate dehydrogenase (LDH) activity. Tf expression was determined by reverse transcriptase-quantitative PCR with human- or mouse-specific probes. hTf and mTf in the medium were assayed by ELISA or radioimmunoassay (RIA), respectively. RESULTS: mTf was mainly localized in retinal pigment epithelium and ganglion cell layers in retina sections of both mouse lines. hTf was abundant in MG cells. The distribution of mTf and hTf mRNA was consistent with these findings. mTf and hTf were secreted into the medium of MG cell primary cultures. Cells from Tg mice secreted hTf at a particularly high level. However, both WT and Tg cell cultures lose their ability to secrete Tf after a few passages. Tg MG cells secreting hTf were more resistant to iron-induced stress toxicity than those no longer secreted hTf. Similarly, exogenous human apo-Tf, but not human holo-Tf, conferred resistance to iron-induced stress on MG cells from WT mice. CONCLUSIONS: hTf localization in MG cells from Tg mice was reminiscent of that reported for aged human retina and age-related macular degeneration, both conditions associated with iron deposition. The role of hTf in protection against toxicity in Tg MG cells probably involves an adaptive mechanism developed in neural retina to control iron-induced stress.

Dimeric transferrin inhibits phagocytosis of residual bodies by testicular rat Sertoli cells.

Transferrin is well known as an iron transport glycoprotein. Dimeric or tetrameric transferrin forms have recently been reported to modulate phagocytosis by human leukocytes. It is mainly synthesized by the liver, and also by other sources, such as Sertoli cells of the testis. Sertoli cells show a strong phagocytic activity toward apoptotic germ cells and residual bodies. Here, we provide evidence that purified human dimeric transferrin from commercial sources decreased residual body phagocytosis, unlike monomeric transferrin. The presence of iron appeared essential for dimeric transferrin inhibitory activity. Importantly, dimeric transferrin could be visualized by immunoblotting in Sertoli cell lysates as well as in culture media, indicating that dimeric transferrin could be physiologically secreted by Sertoli cells. By siRNA-mediated knockdown, we show that endogenous transferrin significantly inhibited residual body ingestion by Sertoli cells. These results are the first to identify dimeric transferrin in Sertoli cells and to demonstrate its implication as a physiological modulator of residual body phagocytosis by Sertoli cells.

Oligodendrocyte differentiation is increased in transferrin transgenic mice.

Transferrin (Tf), the iron transport glycoprotein found in biological fluids of vertebrates, is synthesized mainly by hepatocytes. Tf is also synthesized by oligodendrocytes (Ol), and several lines of evidence indicate that brain Tf could be involved in myelinogenesis. Because Tf is postnatally expressed in the brain, we sought to investigate whether Tf could intervene in Ol differentiation. For this purpose, we analyzed transgenic mice overexpressing the complete human Tf gene in Ol. We show that the hTf transgene was expressed only from 5 days postpartum onward. In the brain of 14-day-old transgenic mice, the DM-20 mRNA level was decreased, whereas the PLP, MBP, CNP, and MAG mRNA levels were increased. We counted a higher proportion of Ol expressing the O4 (Ol-specific antigens) and PLP in brain cells cultured from transgenic mice. These results support the idea that overexpressing Tf in the brain accelerates the oligodendrocyte lineage maturation. Accordingly, by NMR imaging acquisition of diffusion tensor in hTf transgenic mice, we observed early maturation of the cerebellum and spinal cord and more myelination in the corpus callosum. In addition, hTf overexpression led to an increase in Sox10 mRNA and protein. Increases in Sox10 and in Tf expression occur simultaneously during brain development. The Olig1 mRNA level also increased, but long after the rise of hTf and Sox10. The Olig2 mRNA level remained unchanged in the brain of transgenic mice. Our findings suggest that Tf could influence oligodendrocyte progenitor differentiation in the CNS.

Follicle-stimulating hormone activates p70 ribosomal protein S6 kinase by protein kinase A-mediated dephosphorylation of Thr 421/Ser 424 in primary Sertoli cells.

FSH is a major hormonal input that drives Sertoli cells to their fully differentiated function in male reproduction. It is a physiologically important issue to define how FSH mediates its effects at the cellular level to regulate gene expression. FSH biological activities are transduced via a seven-spanned transmembrane receptor, the FSH-R, primarily leading to cAMP-dependent protein kinase A (PKA) activation and cAMP response element binding protein-mediated transcriptional responses. Nevertheless, the intracellular mechanisms interacting with PKA to control Sertoli cell differentiation by FSH are still incompletely defined. Here, we report that, in primary cultures of Sertoli cells isolated from prepubertal rats, FSH enhanced p70S6K enzymatic activity, in a PKA-dependent manner. p70S6K was constitutively phosphorylated on Thr 389, in a manner sensitive to inhibitors of phosphatidyl-inositide-3 kinase and mammalian target of rapamycin. But FSH could not enhance p70S6K phosphorylation on Thr 389. Rather, the hormone induced the dephosphorylation of Thr 421/Ser 424, located in the autoinhibitory domain of p70S6K, in a PKA-dependent manner. Consistently, FSH-induced phosphorylation of the S6 ribosomal protein, a cellular substrate of p70S6K, required PKA activity. In conclusion, these results show that FSH triggers unexpected regulations of p70S6K by dephosphorylation of Thr 421/Ser 424 mediated by PKA, and stimulates S6 phosphorylation, in Sertoli cells.

Myelination and motor coordination are increased in transferrin transgenic mice.

Myelin deficiency in the central nervous system (CNS) can cause severe disabling conditions. Most of the transgenic mice models overexpressing myelin components have limitations for investigators of myelin deficiency and myelin therapy as they severely alter CNS architecture. It has been postulated that transferrin (Tf) is involved in oligodendrocyte (OL) maturation and myelinogenesis. Because Tf is not an intrinsic myelin constituent, we decided to investigate if its overexpression could have an impact on the myelination process without affecting myelin integrity. We generated transgenic mice containing the complete human Tf gene specifically overexpressed in OLs. This overexpression leads to more than a 30% increase in myelin components, such as galactolipids, phospholipids, and proteins. Electron microscopy showed that myelin is structurally normal in terms of thickness and compaction. Behavior analysis showed that mice do not display significant modifications in their locomotion and cognitive and emotional abilities. Furthermore, in one of the genetic background, animals presented a significant increase in motor coordination. We did not find any modification in OL number during early postnatal development, suggesting that Tf does not act on OL proliferation. In addition, the levels of iron and ferritin remained unchanged in the brain of transgenic mice compared to control mice. Our findings indicate that, besides its known iron transport function, Tf is able to influence myelination process and induce behavioral improvements in mice.

Modeling the frequency dependence (5-120 MHz) of ultrasound backscattering by red cell aggregates in shear flow at a normal hematocrit.

The frequency dependence of the ultrasound signal backscattered by blood in shear flow was studied using a simulation model. The ultrasound backscattered signal was computed with a linear model that considers the characteristics of the ultrasound system and tissue acoustic properties. The tissue scattering properties were related to the position and shape of the red blood cells (RBCs). A 2D microrheological model simulated the RBC dynamics in a Couette shear flow system. This iterative model, described earlier [Biophys. J. 82, 1696-1710 (2002)], integrates the hydrodynamic effect of the flow, as well as adhesive and repulsive forces between RBCs. RBC aggregation was simulated at 40% hematocrit and shear rates of 0.05-2 s(-1). The RBC aggregate sizes ranged, on average, from 3.3 RBCs at 2 s(-1) to 33.5 cells at 0.05 s(-1). The ultrasound backscattered power was studied at frequencies between 5-120 MHz and insonification angles between 0-180 degrees. At frequencies below approximately 30 MHz, the ultrasound backscattered power increased as the shear rate was decreased and the size of the aggregates was raised. A totally different scattering behavior was noted above 30 MHz. Typical spectral slopes of the backscattered power (log-log scale) between 5-25 MHz equaled 3.8, whereas slopes down to 0.6 were measured at 0.05 s(-1), between 40-60 MHz. The ultrasound backscattered power was shown to be angle dependent at low frequencies (5-25 MHz). The anisotropy persisted at high frequencies (>25 MHz) for small aggregates (at 2 s(-1)). In conclusion, this study sheds some light on the blood backscattering behavior with an emphasis on the non-Rayleigh regime. Additional experimental studies may be necessary to validate the simulation results, and to fully understand the relation between the ultrasound backscattered power, level of RBC aggregation, shear rate, frequency, and insonification angle.

Sertoli and granulosa cell-specific Cre recombinase activity in transgenic mice.

We have established transgenic mice expressing the Cre recombinase under the control of the anti-Müllerian hormone (AMH) gene promoter. Cre activity and specificity were evaluated by different means. In AMH-Cre mice, expression of the Cre recombinase mRNA was confined to the testis and ovary. AMH-Cre mice were crossed with reporter transgenic lines and the offspring exhibited Cre-mediated recombination only in the testis and the ovary. In male, histochemical analysis indicated that recombination occurred in every Sertoli cells. In female, Cre-mediated recombination was restricted to granulosa cells, but the protein was not evenly active in every cells. From these results, we conclude that potentially, this transgenic line possessing AMH promoter-driven expression of the Cre recombinase is a powerful tool to delete genes in Sertoli cells only, in order to study Sertoli cell gene function during mammalian spermatogenesis.

Simulation of ultrasound backscattering by red cell aggregates: effect of shear rate and anisotropy.

Tissue characterization using ultrasound (US) scattering allows extraction of relevant cellular biophysical information noninvasively. Characterization of the level of red blood cell (RBC) aggregation is one of the proposed application. In the current paper, it is hypothesized that the microstructure of the RBCs is a main determinant of the US backscattered power. A simulation model was developed to study the effect of various RBC configurations on the backscattered power. It is an iterative dynamical model that considers the effect of the adhesive and repulsive forces between RBCs, and the effect of the flow. The method is shown to be efficient to model polydispersity in size, shape, and orientation of the aggregates due to the flow, and to relate these variations to the US backscattering properties. Three levels of aggregability at shear rates varying between 0.05 and 10 s(-1) were modeled at 40% hematocrit. The simulated backscattered power increased with a decrease in the shear rate or an increase in the RBC aggregability. Angular dependence of the backscattered power was observed. It is the first attempt to model the US power backscattered by RBC aggregates polydisperse in size and shape due to the shearing of the flow.