Structure and function of ETAA16: a novel cell surface antigen in Ewing’s tumours

Immunoscreening of an Ewing’s family of tumour (EFT)-derived cDNA library using formerly described EFT-specific antibodies led to the isolation of a 3.5 kb cDNA, named Ewing’s tumour-associated antigen 16 (ETAA16). The ETAA16 cDNA shows no homology to any functionally characterised human gene. Only a bovine cDNA expressed in bovine testis and hepatocytes is functionally characterised as it encodes for a junction plaque associated protein and showed a homology of 69.9% at amino acid level to ETAA16. The human cDNA encodes for a 926 amino acid tumour antigen with a calculated molecular weight of 103 kDa. The epitope of the ETAA16-specific antibody, Ak16, covers the central region of the protein which is part of an extra cellular domain. The human ETAA16 gene locus has been assigned to chromosome 2p13-15 by FISH analyses and is confirmed by the human genome sequencing project. As demonstrated by flow cytometry, the cell surface expression of ETAA16 antigen is restricted to ET cell lines and not expressed on other small blue round cell tumours or other kind of tumour. RT-PCR analysis revealed a high expression of ETAA16 in brain, liver and kidney while lung and heart were negative. Immunohistochemistry showed an intracellular expression of ETAA16 in different kind of non-Ewing tumour tissues. These results suggest that ETAA16 may function as a tumour-specific cell surface antigen in EFTs.     

Modular optical topometric sensor for 3D acquisition of human body surfaces and long-term monitoring of variations.

Optical topometric 3D sensors such as laser scanners and fringe projection systems allow detailed digital acquisition of human body surfaces. For many medical applications, however, not only the current shape is important, but also its changes, e.g., in the course of surgical treatment. In such cases, time delays of several months between subsequent measurements frequently occur. A modular 3D coordinate measuring system based on the fringe projection technique is presented that allows 3D coordinate acquisition including calibrated color information, as well as the detection and visualization of deviations between subsequent measurements. In addition, parameters describing the symmetry of body structures are determined. The quantitative results of the analysis may be used as a basis for objective documentation of surgical therapy. The system is designed in a modular way, and thus, depending on the object of investigation, two or three cameras with different capabilities in terms of resolution and color reproduction can be utilized to optimize the set-up.     

MICROTUBULE PROTEIN DURING CILIOGENESIS IN THE MOUSE OVIDUCT

A colchicine-binding assay and quantitative sodium dodecyl sulfate gel electrophoresis have been used to determine the changes which occur in microtubule protein (tubulin) concentrations in the particulate and soluble fractions of mouse oviduct homogenates during that period of development when centriole formation and cilium formation are at a maximum. When mouse oviducts, at various ages after birth, are homogenized in Tris-sucrose buffer, tubulin concentration is partitioned between the soluble (70%) and particulate (30%) fractions. During the period of most active organelle formation (3–12 days), there is a marked increase in colchicine-binding specific activity, in both the soluble and particulate fractions. Microtubule protein concentration increases from 16 to 24% in the soluble fraction, declining to 14% in the adult. In the particulate fractions, microtubule protein concentration increases from 16 to 27%, leveling off at 16% in the adult. We have concluded from these observations and from electron microscopy that colchicine-binding activity in the particulate fractions is related to the presence of centriole precursors in the pellets of homogenized oviducts from newborn mice. These data further suggest that centriole precursor structures are conveniently packaged aggregates of microtubule protein actively synthesized between 3 and 5 days, and maintained at a maximum during the most active period of organelle assembly.     

Role of calcium permeation in dihydropyridine receptor function. Insights into channel gating and excitation-contraction coupling.

The skeletal and cardiac muscle dihydropyridine receptors (DHPRs) differ with respect to their rates of channel activation and in the means by which they control Ca2+ release from the sarcoplasmic reticulum (Adams, B.A., and K.G. Beam. 1990. FASEB J. 4:2809-2816). We have examined the functional properties of skeletal (SkEIIIK) and cardiac (CEIIIK) DHPRs in which a highly conserved glutamate residue in the pore region of repeat III was mutated to a positively charged lysine residue. Using expression in dysgenic myotubes, we have characterized macroscopic ionic currents, intramembrane gating currents, and intracellular Ca2+ transients attributable to these two mutant DHPRs. CEIIIK supported very small inward Ca2+ currents at a few potentials (from -20 to +20 mV) and large outward cesium currents at potentials greater than +20 mV. SkEIIIK failed to support inward Ca2+ flux at any potential. However, large, slowly activating outward cesium currents were observed at all potentials greater than + 20 mV. The difference in skeletal and cardiac Ca2+ channel activation kinetics was conserved for outward currents through CEIIIK and SkEIIIK, even at very depolarized potentials (at +100 mV; SkEIIIK: tau(act) = 30.7 +/- 1.9 ms, n = 11; CEIIIK: tau(act) = 2.9 +/- 0.5 ms, n = 7). Expression of SkEIIIK in dysgenic myotubes restored both evoked contractions and depolarization-dependent intracellular Ca(2+) transients with parameters of voltage dependence (V(0.5) = 6.5 +/- 3.2 mV and k = 9.3 +/- 0.7 mV, n = 5) similar to those for the wild-type DHPR (Garcia, J., T. Tanabe, and K.G. Beam. 1994. J. Gen. Physiol. 103:125-147). However, CEIIIK-expressing myotubes never contracted and failed to exhibit depolarization-dependent intracellular Ca2+ transients at any potential. Thus, high Ca2+ permeation is required for cardiac-type excitation-contraction coupling reconstituted in dysgenic myotubes, but not skeletal-type. The strong rectification of the EIIIK channels made it possible to obtain measurements of gating currents upon repolarization to -50 mV (Qoff) following either brief (20 ms) or long (200 ms) depolarizing pulses to various test potentials. For SkEIIIK, and not CEIIK, Qoff was significantly (P < 0.001) larger after longer depolarizations to +60 mV (121.4 +/- 2.0%, n = 6). The increase in Qoff for long depolarizations exhibited a voltage dependence similar to that of channel activation. Thus, the increase in Q(off) may reflect a voltage sensor movement required for activation of L-type Ca2+ current and suggests that most DHPRs in skeletal muscle undergo this voltage-dependent transition.     

Diurnal Rhythms of Plasma Ions and Metabolites Levels in Thoroughbred Racehorses

The purposes of this study were to observe the presence of diurnal rhythms in plasma ions and metabolites levels in Thoroughbred racehorses under physical training, and to determine the time of blood sampling in clinical investigations. Plasma calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, glucose, cholesterol, triglycerides, and total proteins levels were studied over a 72-h period. Blood samples were taken every 4 hours from five male and five female Thoroughbred racehorses under physical training. COSINOR analyses (P = 0.05) were done. Plasma potassium and triglycerides showed significant diurnal rhythms, with its acrophases occurring at dark period. No significant diurnal rhythms of other variables were found. It was concluded that, in Thoroughbred racehorses, the optimum time for potassium, and triglycerides sampling seems to be light period. And for other variables, time of diagnosis is not important.     

Epac and phospholipase Cepsilon regulate Ca2+ release in the heart by activation of protein kinase Cepsilon and calcium-calmodulin kinase II

Recently, we identified a novel signaling pathway involving Epac, Rap, and phospholipase C (PLC)epsilon that plays a critical role in maximal beta-adrenergic receptor (betaAR) stimulation of Ca2+-induced Ca2+ release (CICR) in cardiac myocytes. Here we demonstrate that PLCepsilon phosphatidylinositol 4,5-bisphosphate hydrolytic activity and PLCepsilon-stimulated Rap1 GEF activity are both required for PLCepsilon-mediated enhancement of sarcoplasmic reticulum Ca2+ release and that PLCepsilon significantly enhances Rap activation in response to betaAR stimulation in the heart. Downstream of PLCepsilon hydrolytic activity, pharmacological inhibition of PKC significantly inhibited both betaAR- and Epac-stimulated increases in CICR in PLCepsilon+/+ myocytes but had no effect in PLCepsilon-/- myocytes. betaAR and Epac activation caused membrane translocation of PKCepsilon in PLCepsilon+/+ but not PLCepsilon-/- myocytes and small interfering RNA-mediated PKCepsilon knockdown significantly inhibited both betaAR and Epac-mediated CICR enhancement. Further downstream, the Ca2+/calmodulin-dependent protein kinase II (CamKII) inhibitor, KN93, inhibited betaAR- and Epac-mediated CICR in PLCepsilon+/+ but not PLCepsilon-/- myocytes. Epac activation increased CamKII Thr286 phosphorylation and enhanced phosphorylation at CamKII phosphorylation sites on the ryanodine receptor (RyR2) (Ser2815) and phospholamban (Thr17) in a PKC-dependent manner. Perforated patch clamp experiments revealed that basal and betaAR-stimulated peak L-type current density are similar in PLCepsilon+/+ and PLCepsilon-/- myocytes suggesting that control of sarcoplasmic reticulum Ca2+ release, rather than Ca2+ influx through L-type Ca2+ channels, is the target of regulation of a novel signal transduction pathway involving sequential activation of Epac, PLCepsilon, PKCepsilon, and CamKII downstream of betaAR activation.     

Therapeutic efficacy of alpha-1 antitrypsin augmentation therapy on the loss of lung tissue: an integrated analysis of 2 randomised clinical trials using computed tomography densitometry

Background

Two randomised, double-blind, placebo-controlled trials have investigated the efficacy of IV alpha-1 antitrypsin (AAT) augmentation therapy on emphysema progression using CT densitometry.

Methods

Data from these similar trials, a 2-center Danish-Dutch study (n = 54) and the 3-center EXAcerbations and CT scan as Lung Endpoints (EXACTLE) study (n = 65), were pooled to increase the statistical power. The change in 15^th percentile of lung density (PD15) measured by CT scan was obtained from both trials. All subjects had 1 CT scan at baseline and at least 1 CT scan after treatment. Densitometric data from 119 patients (AAT [Alfalastin^® or Prolastin^®], n = 60; placebo, n = 59) were analysed by a statistical/endpoint analysis method. To adjust for lung volume, volume correction was made by including the change in log-transformed total lung volume as a covariate in the statistical model.

Results

Mean follow-up was approximately 2.5 years. The mean change in lung density from baseline to last CT scan was -4.082 g/L for AAT and -6.379 g/L for placebo with a treatment difference of 2.297 (95% CI, 0.669 to 3.926; p = 0.006). The corresponding annual declines were -1.73 and -2.74 g/L/yr, respectively.

Conclusions

The overall results of the combined analysis of 2 separate trials of comparable design, and the only 2 controlled clinical trials completed to date, has confirmed that IV AAT augmentation therapy significantly reduces the decline in lung density and may therefore reduce the future risk of mortality in patients with AAT deficiency-related emphysema.

Trial registration

The EXACTLE study was registered in ClinicalTrials.gov as ''Antitrypsin (AAT) to Treat Emphysema in AAT-Deficient Patients''; ClinicalTrials.gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT00263887","term_id":"NCT00263887"}}NCT00263887.