Endoplasmic reticulum Ca(2+)-ATPase in microsomal vesicles isolated from bovine retinae

Active Ca2+ transport was measured in microsomal vesicles prepared from bovine retinae and was compared with that in disk membranes of the photoreceptor cells of the same retina. The 45Ca uptake was dependent on the presence of Mg(2+)-ATP and was inhibited by vanadate or when GTP substituted for ATP. The dependence of calcium uptake on the external free Ca2+ concentration gave a KM = 13 microM or a KM = 0.1 microM for disks and microsomal vesicles, respectively. A phosphorylated intermediate (E-P) of Ca(2+)-ATPase of about 100 kDa was isolated in microsomal vesicles. The E-P formation was strongly inhibited by thapsigargin and partially by 2,5-di-(-butyl)benzohydroquinone. Digestion of disks or microsomes with calpain had no effect on the phosphorylated intermediate, while digestion with trypsin produced two fragments of approximately 55 kDa and 35 kDa. These results suggest that bovine retinal microsomes contain a calcium pump belonging to the SERCA family.     

Flow-cytometric detection of the RI alpha subunit of type I cAMP-dependent protein kinase in human cells

cAMP-dependent protein kinase (PKA) is composed of two genetically distinct catalytic (C) and regulatory (R) subunits. There are two different classes of PKA, designated as type I and type II, which contain distinct R subunits (RI or RII, respectively) but share a common C subunit. Enhanced expression of type I PKA has been correlated with cell proliferation and neoplastic transformation. Detection of the different PKA subunits is usually performed by photoaffinity labeling with 8-N3-32P-cAMP or by radioimmunolabeling techniques. Both techniques are time consuming and require a high number of cells and the use of radioactive reagents. Using the MCF-10A normal human mammary cell line infected with a recombinant retroviral vector containing the human RI alpha gene (MCF-10A RI alpha), we have developed a flow-cytometric assay to detect the intracellular content of RI alpha protein in human cells. MCF-10A and MCF-10A RI alpha cells were fixed in 1.5% paraformaldehyde at 37 degrees C for 15 min and permeabilized by methanol and acetone (1:1) at -20 degrees C for 5 min before staining with a specific IgG2a MoAb followed by a FITC-conjugate rabbit-anti mouse IgG. This procedure was also successfully utilized to recognize RI alpha protein content in human peripheral blood lymphocytes. Flow-cytometric detection of the RI alpha subunit in human cells is feasible and allows the study of the role of type I PKA in cell growth and neoplastic transformation.     

Variability of intact rock mechanical properties for some metamorphic rock types and its implications on the number of test specimens

Intact rock strength and stiffness properties are commonly used in rock mass mechanical characterization, and their evaluation is usually based on laboratory tests. Due to the variability that affects strength and stiffness parameters, the determination of the number of laboratory-tested specimens required to obtain a reliable reference value is very useful. However, many studies reported in apposite literature focused only on the variability of strength parameters. This study investigates the variability of some of the most important strength and stiffness properties (unconfined compressive strength, indirect tensile strength, tangent and secant Young’s moduli, Poisson’s ratio) by applying statistical methods (statistical decision theory and statistical inference theory). A data set of 451 laboratory tests was used, performed on three rock types. The statistical analyses were applied with the aim of assessing how closely intact rock laboratory data follow a normal distribution and determining the minimum number of specimens required to obtain a reliable average value of the parameters in relation to a targeted precision index for a confidence level of 95 %. The results indicate that the minimum number of samples needed varies depending on rock and test types. Among the stiffness properties, tangent Young’s modulus has a lower variability than both the secant modulus and the Poisson’s ratio, whereas in terms of strength parameters, unconfined compressive strength is subject to greater variability than indirect tensile strength.     

Analyses and design of 95-GHz SoC CMOS radiometers for passive body imaging

Passive radiometry is a health-safe alternative to other imaging techniques conceived to be used on human beings for security screening or medical imaging applications. In this work we address a study on the feasibility of W-band passive radiometers in nano-scale CMOS technology for imaging applications. In particular, this study takes into account some of the most relevant aspects regarding the system-on-a-chip implementation, from system to circuit and technology limitations, with emphasis on the impact of the non-idealities of the detector on the overall system performances. Excluding the hardware differences between the investigated receiver architectures and their substantial implications, especially in case of array systems, the investigation shows how there is no a clear evidence to identify a priori the best performance receiver architecture, but it depends on the circuits, as well as operating frequency and technology.     

Hysteretic Critical State in Coplanar Josephson Junction with Monolayer Graphene Barrier

Coplanar Al/graphene/Al junctions fabricated on the same graphene sheet deposited on silicon carbide (SiC), show robust Josephson coupling at subKelvin temperature, when the separations between the electrodes is below 400 nm. Remarkably, a hysteretic Critical State sets in when ramping an orthogonal magnetic field, with a sudden collapse of the Josephson critical current I _c when turning the field on, and a revival of I _c when inverting the sweep. Similar hysteresis can be found in granular superconducting films which may undergo the Berezinskii-Kosterlitz-Thouless transition. Here, we give quantitative arguments to prove that this odd behavior of the magnetoconductance gives evidence for an incipient Berezinskii-Kosterlitz-Thouless transition with drift and pinning of fluctuating free vortices induced by the current bias.     

Effect of maternal betamethasone administration at midgestation on baboon fetal adrenal gland development and adrenocorticotropin receptor messenger ribonucleic acid expression

Although fetal pituitary ACTH is important to fetal adrenal growth and steroidogenesis in the second half of primate pregnancy, its role in adrenal development and function has not been established in vivo in the first half of gestation. In the present study, therefore, baboons were treated at midgestation with betamethasone to determine the effect of fetal pituitary ACTH on fetal adrenal growth, development, and ACTH receptor and P-450 enzyme messenger ribonucleic acid (mRNA) levels. The administration of betamethasone to baboon mothers on days 60-99 of gestation (term = 184 days) decreased fetal pituitary POMC mRNA levels by 54% (P < 0.01) and fetal serum ACTH levels to undetectable values (P < 0.05). The decline in ACTH was associated with decreases in fetal adrenal weight (P < 0.001), cortical cell size (P < 0.05), appearance of apoptosis and cellular disorganization, and a loss of immunocytochemically demonstrable definitive zone-specific delta5-3beta-hydroxysteroid dehydrogenase expression. The concomitant administration of ACTH and betamethasone restored these aspects of adrenal integrity to normal. Moreover, there was approximately a 95% decrease (P < 0.01) in fetal adrenal expression of ACTH receptor, P-450 cholesterol side-chain cleavage, and P-450 17alpha-hydroxylase 17/20-lyase mRNA levels after betamethasone administration. We conclude that fetal pituitary ACTH is necessary for the growth and development of fetal and definitive cortical zones and the marked coordinated increase in ACTH receptor and maintenance of P-450 cholesterol side-chain cleavage/P-450 17alpha-hydroxylase 17/20-lyase expression in the baboon fetal adrenal gland during the first half of gestation.     

A comparative evaluation of halo pin designs in an immature skull model

To design an improved halo pin for use in pediatric patients, three commonly used halo pins were evaluated with a mechanical testing apparatus and segments of prepared fetal calf skull. The pins were driven through the bone segments while the load at the bone-pin interface was measured. New pins were designed with respect to pin tip and flange width and similarly compared. Mean maximum loads to penetration, normalized for bone segment thickness, were 55.6 N/mm for the PMT Corporation pin, 61.5 N/mm for the Bremer pin, and 73.6 N/mm for the Ace pin. Four new, short tipped pins were designed and compared with the Ace pin, and there was no significant difference. Finally, four new pins were designed with varying flange widths. Mean maximum loads, normalized for bone segment thickness, were 68.9 N/mm for the 4.2 mm flange, 72.2 N/mm for the 4.7 mm flange, 92.9 N/mm for the 5.2 mm flange, and 96.4 N/mm for the 5.7 mm flange. The findings of this investigation are clinically important because they may help to explain the variability in the complication rates seen with the use of different halo systems in children. The three halo pins currently on the market have different pin designs, including tip lengths and flange distances, which contribute to the difference in load to penetration for each pin. The new, wide flanged, short tipped halo pin design might decrease the complication rate of halo use in children by providing an improved capacity to resist penetration despite increased loads of application.     

An electrochemical impedance investigation of the behaviour of anodically oxidised titanium in human plasma and cognate fluids,relevant to dental applications

In dental applications, the contact between the metal implant and the receiving living tissue is made through the oxide layer on the implant surface, which allows the osseointegration process. In dentistry, the passive film formed on titanium seems to be more stable and protective than that formed on the Ti alloys, customarily used in other medical applications. Corrosion of titanium alloys in the mouth can result from the presence of a number of corrosive species, such as the hydrogen ion (H(+)), sulfide compounds (S(2-)), dissolved oxygen (O(2)) and Cl(-) and can result in the release of Ti(4+) ions that, in turn, brings about the reduction of alkaline phosphatase activity of osteoblastic cells. The present study reports a time-dependent electrochemical corrosion study of titanium in contact with the following biologically relevant solutions: (i) SBF (simulating the inorganic part of human plasma), (ii) SBF with added ovalbumin (a protein simulating the post-implant environment) and (iii) human plasma. To the best of the authors' knowledge, this is the first report on the corrosion of Ti in human plasma. The electrochemical measurements are based on electrochemical impedance spectrometry. Impedance spectra were interpreted on the basis of the equivalent-circuit approach and estimates of the time-variation of oxide film thickness and resistance were computed. Surface Raman spectroscopy was used to characterise the structure of as-anodised and corroded TiO(2) films: the effects of phosphate and organic incorporation were highlighted. EIS and surface Raman measurements have demonstrated that the corrosion resistance of the oxide films formed on Ti is strongly affected by the presence of biomolecules in the chloride- and phosphate-based aqueous solution. In particular, ovalbumin increases corrosion performance and human plasma is found to be remarkably more aggressive in comparison to SBF. These results suggest some caution in extrapolating corrosion results obtained in simulated biological fluids to the actual behaviour in vivo.     

The significance of the three volar spaces in forearm compartment syndrome: a clinical and cadaveric correlation

The goal of this study was to assess the importance of the 3 volar spaces in forearm compartment syndrome in a prospective manner. A cadaveric model was developed to correlate with our clinical experience. All but 1 of 21 volar compartments (superficial volar, deep volar, and pronator quadratus spaces) in 7 patients in our clinical series decompressed adequately after release of the superficial volar fascia. One patient needed further release of the pronator quadratus compartment; he had suffered a combined crush and vascular injury. All volar compartments in our cadaveric model decompressed with superficial fasciotomy. Prefasciotomy and postfasciotomy pressures should be obtained from all 3 compartments of the volar forearm. Superficial fasciotomy usually adequately decompresses the entire volar forearm; however, in the event that deep compartment pressures remain high after superficial fasciotomy, release of the affected space is indicated.