CVD Lu(2)O(3):Eu coatings For Advanced Scintillators.

Currently Lu(2)O(3):Eu(3+) scintillators can only be fabricated via hot-pressing and pixelization, which is commercially not viable, thus restricting their use. Chemical vapor deposition is being developed as an alternative manufacturing process. Columnar coatings of Lu(2)O(3):Eu(3+) have been achieved using the halide-CO(2)-H(2) system, clearly signifying feasibility of the CVD process. Characterization of the coatings using high resolution scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis have been used as an aid to optimize process parameters and attain highly oriented and engineered coating structures. These results have clearly demonstrated that this process can be successfully used to tailor sub-micron columnar growth of Lu(2)O(3):Eu(3+), with the potential of ultra high resolution x-ray imaging.

Effects of titanium nanotubes on the osseointegration, cell differentiation, mineralisation and antibacterial properties of orthopaedic implant surfaces.

The development and pre-clinical evaluation of nano-texturised, biomimetic, surfaces of titanium (Ti) implants treated with titanium dioxide (TiO2) nanotube arrays is reviewed. In vitro and in vivo evaluations show that TiO2 nanotubes on Ti surfaces positively affect the osseointegration, cell differentiation, mineralisation, and anti-microbial properties. This surface treatment can be superimposed onto existing macro and micro porous Ti implants creating a surface texture that also interacts with cells at the nano level. Histology and mechanical pull-out testing of specimens in rabbits indicate that TiO2 nanotubes improves bone bonding nine-fold (p = 0.008). The rate of mineralisation associated with TiO2 nanotube surfaces is about three times that of non-treated Ti surfaces. In addition to improved osseointegration properties, TiO2 nanotubes reduce the initial adhesion and colonisation of Staphylococcus epidermidis Collectively, the properties of Ti implant surfaces enhanced with TiO2 nanotubes show great promise. Cite this article: Bone Joint J 2018;100-B(1 Supple A):9-16.

Expression of carcinoembryonic antigen and its predicted immunoglobulin-like domains in HeLa cells for epitope analysis.

Carcinoembryonic antigen (CEA) is a member of the immunoglobulin gene superfamily with one predicted variable domain-like region (N domain; 108 amino acids) and three sets of constant domain-like regions (A1B1, A2B2, and A3B3; 92 amino acids for A domains and 86 amino acids for B domains). In addition, CEA possesses two signal peptides, one at the amino terminus and one at the carboxyl terminus. Both are removed during posttranslational processing, with the one at the carboxyl terminus being replaced by a glycosylphosphatidylinositol (GPI) moiety. We have previously expressed the full length complementary DNA clone for CEA in Chinese hamster ovary cells and murine L cells, demonstrating proper processing of nascent polypeptide chains to mature, fully glycosylated CEA including the GPI anchor. Using the same full length CEA complementary DNA clone and the polymerase chain reaction, we have now constructed expression clones for secreted versions of the N domain, the A3B3 domain, and the A3 and B3 subdomains. The clones were expressed in HeLa cells using the beta-actin promoter. A stop codon was introduced at the end of the A3B3 and the A3 and B3 domains to allow secretion instead of retention on plasma membranes with the GPI anchor. Expressed products were purified to homogeneity by affinity chromatography using monoclonal antibodies specific for each domain and by reversed phase high pressure liquid chromatography. Purified domains were characterized by Western blotting, antibody binding and inhibition studies, amino-terminal sequence and amino acid analyses, and laser desorption/time of flight mass spectrometry. These analyses revealed that the monomeric N domain is of size 15,990, with a glycosylation mass of about 4100, in good agreement with two N-linked glycosyl units of about mass 2100. There is some evidence that the N domain forms dimers. The N domain reacted with antibodies specific for this domain with an affinity similar to that of intact CEA. The A3B3 domain had a mass of 34,462, with a glycosylation mass of 14,900, in good agreement with seven N-linked glycosylation sites of average mass 2100. The A3B3 domain reacted only with antibodies specific for this domain, with a slightly lower affinity than that of native CEA. The amino-terminal sequences of the N domain and A3B3 domain proteins demonstrated proper processing of the signal peptide.(ABSTRACT TRUNCATED AT 400 WORDS)

Surfactant peptides stimulate uptake of phosphatidylcholine by isolated cells.

To determine whether small hydrophobic surfactant peptides (SP-B and SP-C) participate in recycling of pulmonary surfactant phospholipid, we determined the effect of these peptides on transfer of 3H- or 14C-labelled phosphatidylcholine from liposomes to isolated rat alveolar Type II cells and Chinese hamster lung fibroblasts. Both natural and synthetic SP-B and SP-C markedly stimulated phosphatidylcholine transfer to alveolar Type II cells and Chinese hamster lung fibroblasts in a dose- and time-dependent fashion. Effects of the peptides on phospholipid uptake were dose-dependent, but not saturable and occurred at both 4 and 37 degrees C. Uptake of labelled phospholipid into a lamellar body fraction prepared from Type II cells was augmented in the presence of SP-B. Neither SP-B nor SP-C augmented exchange of labelled plasma membrane phosphatidylcholine from isolated Type II cells or enhanced the release of surfactant phospholipid when compared to liposomes without SP-B or SP-C. Addition of native bovine SP-B and SP-C to the phospholipid vesicles perturbed the size and structure of the vesicles as determined by electron microscopy. To determine the structural elements responsible for the effect of the peptides on phospholipid uptake, fragments of SP-B were synthesized by solid-phase protein synthesis and their effects on phospholipid uptake assessed in Type II epithelial cells. SP-B (1-60) stimulated phospholipid uptake 7-fold. A smaller fragment of SP-B (15-60) was less active and the SP-B peptide (40-60) failed to augment phospholipid uptake significantly. Like SP-B and SP-C, surfactant-associated protein (SP-A) enhanced phospholipid uptake by Type II cells. However, SP-A failed to significantly stimulate phosphatidylcholine uptake by Chinese hamster lung fibroblasts. These studies demonstrate the independent activity of surfactant proteins SP-B and SP-C on the uptake of phospholipid by Type II epithelial cells and Chinese hamster lung fibroblasts in vitro.

In vitro translation, post-translational processing and secretion of pulmonary surfactant protein B precursors.

Surfactant proteolipid SP-B is a hydrophobic protein of Mr = 8000 identified in organic solvent extracts of pulmonary surfactant. Analysis of the human SP-B RNA predicts that the active surfactant peptide is derived by proteolysis of an Mr = 40,000 precursor. In the present work, characteristics of synthesis, secretion and processing of SP-B were demonstrated in a pulmonary adenocarcinoma cell line by immunoprecipitation of radiolabelled precursors. Treatment of cells with tunicamycin resulted in synthesis and secretion of unglycosylated proSP-B of Mr = 39,000. Immunoprecipitation of protein produced by in vitro translation of human lung poly(A)+ RNA detected an Mr = 40,000 protein; the size discrepancy is likely related to cleavage of a leader signal sequence. Endoglycosidase-H-sensitive precursors of Mr = 41,000-43,000, pI = 5.1-5.4 were the first isoforms detected within the cells and were processed to endoglycosidase-H-resistant isoforms and secreted. Neuraminidase and endoglycosidase-F-sensitive forms of proSP-B were first detected in the media at 60 min as Mr = 42-46,000 isoforms with pI = 4.6-5.1. Proteolytically processed isoforms of proSP-B were detected primarily in the media and were generated by cleavage of an amino-terminal Mr = 16,000 peptide resulting in Mr = 27,000-33,000 isoforms (pH = 5.6-6.8). The Mr = 27,000-33,000 isoforms were sensitive to neuraminidase, resulting in isoforms with pH = 6.0-6.8. Digestion of the Mr = 27,000-33,000 peptide with endoglycosidase-F resulted in isoforms of Mr = 23,000, pH = 6.0-6.8. The endoglycosidase-F-resistant peptide of Mr = 16,000, pI = 4.2-4.4 was identified with an antiserum generated against synthetic peptides derived from the amino-terminal domain, as deduced from the SP-B DNA sequence. Further proteolytic processing of the Mr = 27,000-33,000 isoforms to the Mr = 8000 peptide detected in surfactant was not observed in this cell line. Thus, in the H441-4 cells (a cell line with morphologic features of Clara cells), SP-B is synthesized as a preproprotein which undergoes cleavage of a signal sequence and addition of asparagine-linked carbohydrate; proSP-B is secreted by processes which are independent of glycosylation. SP-B peptides of Mr = 27,000-33,000 and Mr = 16,000, representing carboxy and amino-terminal domains, accumulate in the media.

Mouse monoclonal antibody 5-21-3 recognizes a contiguous, conformation-dependent epitope and maps to a hydrophilic region in HIV-1 gp41.

Mouse monoclonal antibody 5-21-3 is mapped to an epitope within a hydrophilic region of HIV-1 gp41 between amino acids 642 and 665 (numbering by Meyers et al. based on HXB2 isolate). The epitope is formed from amino acids within the sequence IHSLIEESQNQQEKNEQELLELDK; however, antibody 5-21-3 is unable to recognize the epitope-forming sequence when it is presented to the antibody in the form of a short (642-665) synthetic polypeptide. The epitope apparently is partially formed when additional native sequence of varying length is added to the amino and/or carboxy ends of the epitope-forming sequence, and 5-21-3 binds these larger synthetic polypeptides to varying degrees depending on the position and length of the flanking sequences. The 5-21-3 epitope apparently is formed from contiguous amino acids which require a specific, conformation-dependent, secondary structure for proper epitope formation. Binding preferences exhibited by 5-21-3 toward synthetic polypeptides and recombinant proteins may reflect the conformational nature of the epitope in disrupted HIV which elicited formation of the monoclonal.

Identification of surfactant proteolipid SP-B in human surfactant and fetal lung.

Surfactant proteolipid (SP-B) is one of several hydrophobic peptides detected in organic extracts of pulmonary surfactant and associated with the dramatic surface-active properties of surfactant phospholipids. In the present study human SP-B was identified as a protein with a relative molecular weight (Mr) of 7,500-8,000 under reducing conditions; protein of Mr 18,000 was detected under nonreducing conditions by immunoblot analysis of organic extracts of bovine and human surfactant utilizing an antiserum directed against a 60-amino acid synthetic SP-B peptide. This peptide antiserum was subsequently used to identify SP-B in explant cultures of 18- to 23-wk gestation human fetal lung. Immunoprecipitation of explants labeled with [35S]methionine after 48 h of culture identified proteins of Mr 40,000-42,000, 25,000, and 18,000 after electrophoresis under nonreducing conditions. The Mr 18,000 form was reduced to Mr 7,500-8,000 in the presence of beta-mercaptoethanol. These molecular forms likely represent the SP-B precursor protein, a proteolytic intermediate, and the mature SP-B peptide, respectively. Immunocytochemistry with the peptide antiserum localized SPL(Phe) in granular inclusions in the apical region of type II-like epithelial cells, a pattern of staining similar to that observed for the major surfactant-associated protein of Mr 26,000-38,000 (SP-A). SP-B is a novel pulmonary surfactant-associated protein that is synthesized by the human alveolar type II epithelial cell as an Mr 40,000-42,000 precursor that is subsequently proteolytically processed to Mr 7,500-8,000.

Mechanobiology and joint conformity regulate endochondral ossification of sesamoids.

Sesamoid bones form by the endochondral ossification of sesamoid cartilages. This ossification process is thought to be similar to that responsible for the formation of secondary ossific nuclei in long-bone epiphyses. Sesamoids ossify much later in development than do epiphyses, however, and bone formation within sesamoids often begins by way of multiple ossific nuclei. Endochondral growth and ossification in the formation of secondary ossific nuclei have previously been correlated with distributions of the octahedral shear and hydrostatic stresses generated in vivo within cartilage anlagen. In this study, we used two-dimensional finite element analysis to predict the distributions of octahedral shear and hydrostatic stresses in an idealized model of a sesamoid cartilage subjected to in vivo loading. We examined the influence of sesamoid joint conformity. The distribution of an osteogenic stimulus was calculated with an approach similar to that used to predict epiphyseal ossification. The results suggest that, compared with conforming joints, nonconformity between the sesamoid cartilage and its articulating surface, which arises during early development, produces higher contact pressures within the sesamoid and leads to a thicker articular cartilage layer. For a nonconforming joint surface, the results suggest that ossification is favored anywhere within a broad internal region of the sesamoid, whereas a layer at the articular surface will remain cartilaginous. These findings highlight the subtle differences between ossification processes in epiphyses and sesamoids, indicating that the mechanical stress environment in sesamoids produces a diffuse stimulus leading to the onset of ossification and that the degree of joint nonconformity may influence the thickness of the articular cartilage layer.

Effects of surfactant-associated protein SP-B synthetic analogs on the structure and surface activity of model membrane bilayers.

The effect of several synthetic peptides based on the sequence of human pulmonary surfactant-associated protein B (SPB) on the molecular packing of model membrane lipids (7:1 dipalmitoyl phosphatidylcholine (DPPC)/dipalmitoyl phosphatidylglycerol (DPPG)) was studied using fluorescence anisotropy. This information was then correlated with complementary biophysical data obtained on both a modified Wilhelmy-Langmuir balance and a pulsating bubble surfactometer. The SP-B peptides examined in these studies are synthetic human SP-B Phe1-Ser78 (SP-B 1-78, full-length sequence), synthetic human SP-B Phe1-Thr60 (SP-B 1-60), synthetic human SP-B Phe1-Ala20 (SP-B 1-20), synthetic human SP-B Ala20-Thr60 (SP-B 20-60), synthetic human SP-B Leu27-Ser78 (SP-B 27-78), synthetic human SP-B Leu40-Thr60 (SP-B 40-60) and synthetic human SP-B Tyr53-Ser78 (SP-B 53-78). trans-parinaric acid was utilized to detect changes in ordering of lipids within the interior upon incorporation of synthetic SP-B peptide, whereas 1-hexadecanoyl-2-[N-(7-nitro-2-benzoxa-1,3-diazol-4-yl)-a min ohexanoyl] phosphatidylcholine (6-NBD-PC) and 1-acyl-2-[N-(7-nitro-2-benzoxa-1,3-diazol-4-yl)aminohexanoyl ] phosphatidylglycerol (6-NBD-PG) were utilized to determine alterations in lipid order at the surface of the model membrane bilayer. With the exception of SP-B 40-60, which corresponds to the most hydrophobic segment of the full-length SP-B, none of the other peptide significantly perturbed the interior bilayer as determined by fluorescence anisotropy of trans-parinaric acid. Incorporation of any of the peptides with the exception of SP-B 40-60, resulted in an increase in anisotropy of NBD-PC. The most significant enhancements resulted from the addition of SP-B 1-78, SP-B 1-20, SP-B 27-78 or SP-B 53-78. The magnitude of anisotropy increase with these peptides is similar to that observed with an equivalent molar ratio of native SP-B isolated from a bovine source. These observations suggest that these four synthetic peptides have the structural and compositional characteristics required for surface ordering of the membrane bilayer in a manner similar to that observed with native SP-B, thereby facilitating the surfactant-like properties of phospholipid mixtures.

Flow of an elastico-viscous liquid in a curved pipe of slowly varying curvature.

Curvature forms an important feature of thoracic aorta and this paper deals with the flow of an idealized elastico-viscous liquid in a curved pipe of circular cross-section and slowly varying curvature, under a pressure gradient. The flow is assumed to be steady and at low Reynolds numbers. By using the series expansion method of Dean (Phil Mag 4 (1927) 208-223; Phil Mag 5 (1928) 673-693) in powers of a parameter L, which can be considered as the square of ratio of the centrifugal force induced by the circular motion of the fluid to the viscous force, it is shown that in a tube of increasing curvature, there will be delay in setting up of the secondary motion. The wall shear stress, an important parameter in physiological flows, is calculated. The flow of Newtonian fluid in a tube of circular cross section is discussed, as a particular case.

A four compartment model to study the kinetics of strontium metabolism in man.

Many drugs confer upon the body the characteristics of a four compartment model. This paper deals with the estimation of pharmacokinetic parameters of a four compartment model to study the distribution of strontium in the organism. The central compartment (where the introduction of the material takes place) is connected to two other compartments (which represent the organic fluids) and one of them is connected to the fourth compartment (which represents the fraction that can be exchanged in the bone). The elimination from the central compartment is through urine and the elimination from the third compartment is in the form of a non-exchangeable deposit. The method of solution involves an optimization method which provides the global minimum of delta, a single variable function. The model is tested for different sets of data and the results are compared with those obtained by the generalized least square method.

A four compartment linear mammillary model.

Studies are made for a four compartment model in which the central compartment is connected reversibly to three other compartments and the elimination occurs from the central compartment only. Identification of different distribution rate constants is made, with concentrations of drug in the central compartment at different times of observation being known. The solution depends on an optimization method in which the different unknowns are reduced to single variable with the help of Archimedes spiral. Thus, the solution requires the global minimum of a functional of single variable. Results are compared with those obtained by the generalized least square method.

Pharmacokinetics of estulic [corrected] in humans.

Estulic [corrected] given orally without food after overnight fast produces a blood concentration curve with a pronounced second peak that does not appear when the drug is taken with food. A two-compartment open model involving two different time lags is used to study the pharmacokinetics of estulic [corrected] in humans after oral administration. The drug accumulates in a tissue or organ that is well perfused in the first pass transfer. The accumulation appears to occur by a competitive process. The second peak apparently is the result of a rapid release of drug and bioreversible drug compounds from the hepatic-biliary system with subsequent reabsorption. This release may occur spontaneously, but appears to be triggered by food intake. We use an optimization method to characterize the pharmacokinetic profiles of drug for this model. This technique which provides the global minimum of the deviation delta, from the given observations, leads to the optimization of a single variable function. The results are compared with those obtained from the generalized least squares method.

A three-compartment open model with first order absorption.

Many drugs confer upon the body the characteristics of a three-compartment model. This paper deals with the estimation of pharmacokinetic parameters of a three-compartment open model, with first order absorption from plasma level data. The central compartment (e.g. plasma) is connected to two other peripheral compartments, and (elimination occurs from only the central compartment. The method of solution involves an optimization method which provides a global minimum of delta, the deviation of plasma concentration from the observed values. The distribution volume of the central compartment and the lag time are also identified. The uniqueness of the absorption rate constant is obtained by the minimum energy principle. The model is tested for different sets of data for the drug Guanfacine (Sandoz laboratories), and the results are compared to those obtained by the generalised least square method.

Stenotic effects in a tube of elliptic cross-section at low Reynolds numbers.

With an objective to understanding arteriosclerosis, the blood flow in a cylindrical tube with local constriction is analysed. The cross-section of the tube is an ellipse, the axes of which are in an arbitrary position with respect to the axis of the tube. Blood is taken to be a Newtonian and homogeneous fluid. The cross-sectional area varies slowly with the longitudinal distance and the area change is so adjusted to take account of stenosis. The transverse velocity field and the effects of inertia on the primary velocity and pressure distribution are calculated to a first order in the relevant small parameter and effects of asymmetry on the wall shear stress and impedance are presented.

A four compartment open model with first-order absorption.

This paper is related to the identification of pharmacokinetic parameters of a four-compartment open model with first order absorption from plasma level data. The eigenvalues of the characteristic matrix of the given system are obtained by transforming them into a single variable and the solution involves the minimization of the sum of squares of deviation of the model-predicted values of the state variables from an experimentally obtained values. The distribution volume and the lag time are also identified. Finally, the unicity of the absorption rate constant is obtained by the minimum energy principle. The results obtained with present method are compared with those obtained by the generalized least squares method.

A three compartment open model with two time lags.

The present study deals with the identification of exchange parameters involved in a three-compartment open model with two time lags in which elimination occurs from the central compartment. Two different optimization methods have been used which involve the reduction of different unknowns to a single variable theta, with the help of Archimedes Spiral. Thus, the solution requires the global minimum of a functional of single variable theta. Results are compared with those obtained by the generalized least square method.

Sequence-specific fragmentation from oligopeptides using plasma-desorption mass spectrometry.

252Cf plasma-desorption mass spectrometry (PDMS) has been demonstrated to provide sequence-specific fragmentation for several oligopeptides. The nature of the fragment ions observed is generally similar to that observed using liquid secondary-ion mass spectrometry (LSIMS) and can be observed using less sample than LSIMS requires, but PDMS spectra are acquired at a lower resolution. In addition, the molecular weight of some of the oligopeptides studied exceeds that which is generally accepted as within the sequence range of LSIMS. The specific series of sequence ions that predominate in the PDMS spectra appear to be related to the amino acid compositions and sequences of the oligopeptides.

General treatment of linear mammillary models.

This paper deals with the mathematical analysis of time courses of absorption, distribution and elimination of drug in a body, which is of considerable value in developing dosage schedules to provide optimal therapeutic action and to reduce the unwanted side effects due to accumulation of drug in the body to a minimum. We consider a general n-compartment model, where elimination occurs from the central compartment which, in turn, is connected reversibly with all other compartments. This linear mammillary model can be used to study the kinetics of protein metabolism in organism. We use an optimization method to characterize the pharmacokinetic profiles of drug for a general n-compartment model. Results are compared to those obtained by making use of (a) SAAM program and (b) an asymptotic method.