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Biomedical subjects

G Hayes

Publications and source records attributed to G Hayes.

At least 19 recordsLinked to original sources
PubMed2006

Potential contributions to disability theorizing and research from positive pyschology.

PURPOSE: Within the context of taking the perspectives of disabled individuals themselves more seriously, it is imperative that researchers and practitioners accord due primacy to the experiential worlds and everyday lived experiences of individuals with disabilities. Based on the premise that theoretical groundedness (along with methodological rigour) is integral to sound research, it is argued that the existing body of knowledge regarding the lived experiences of individuals with disabilities may be complemented by a conceptual placing of understandings of disability in relation to a prominent theoretical pathway at the moment, namely, the interdisciplinary emphasis on human strengths and wellness. METHOD: A critical engagement with key conceptualizations of disability entailed a focus on the development, strengths, and challenges of medical, social and psychologically based conceptualizations of disability. RESULTS AND CONCLUSION: The existing body of knowledge around disability may be extended and complemented by key concepts regarding human health/wellness from the field of Positive Psychology. Positive Psychology's keynote contribution to the study of disability and rehabilitation entails directing researchers and practitioners to the aim of building, reinforcing and extending disabled individuals' strengths and capacities in order to optimize their functioning in all areas of life, and thereby promote wellness.

Cerebral Palsy↗
PubMed2005

Effect of cobalt doping on the phase transformation of TiO2 nanoparticles.

Co-doped TiO2 nanoparticles containing 0.0085, 0.017, 0.0255, 0.034, and 0.085 mol % Co(III) ion dopant were synthesized via sol-gel and dip-coating techniques. The effects of metal ion doping on the transformation of anatase to the rutile phase have been investigated. Several analytical tools, such as X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray analysis (EDAX) were used to investigate the nanoparticle structure, size distribution, and composition. Results obtained revealed that the rutile to anatase concentration ratio increases with increase of the cobalt dopant concentration and annealing temperature. The typical composition of Co-doped TiO2 was Ti(1-x)Co(x)O2, where x values ranged from 0.0085 to 0.085. The activation energy for the phase transformation from anatase to rutile was measured to be 229, 222, 211, and 195 kJ/mole for 0.0085, 0.017, 0.0255, and 0.034 mol % Co in TiO2, respectively.

Biocompatible Materials↗
PubMed2003

Incidence of cryptorchidism in dogs and cats.

Over a period of 54 months, 3518 dogs and 3806 cats were castrated; 240 of the dogs and 50 of the cats were cryptorchid. Pedigree dogs, in particular the German shepherd dog, boxer and chihuahua were over-represented. Among the dogs, right-sided inguinal cryptorchidism was the most common form, followed by right-sided abdominal cryptorchidism. The location of the affected testicle(s) was most variable in the boxer. Among the cats, left- or right-sided inguinal cryptorchidism were the most common forms of the condition.

Animals↗
PubMed2002

The influence of liquid binder on the liquid mobility and preparation of spherical granules by the process of extrusion/spheronization.

The influence of the type of liquid on the movement of water and the performance of the preparation of pellets by the process of extrusion/spheronization has been studied. Liquid movement was assessed by a pressure membrane technique and by extrusion, while the pellet properties were assessed in the terms of their median size, size range (interquartile range), roundness (by a two-dimensional shape factor) and porosity. The model formulations studied were microcrystalline cellulose (MCC) and mixtures of MCC and barium sulphate at 20, 50 and 80% levels. The liquids were water, a 25% solution of glycerol in water and an anionic surfactant (sodium lauryl sulphate) below its c.m.c. and two concentrations (0.01 and 0.0001%) of a non-ionic surfactant (Pluronic PF68). The presence of the different liquids changed the ease and extent with which the liquid could be removed (drying) and reabsorbed (wetting), resulting in lower levels of saturation with the glycerol solution and considerably increased levels of saturation with the surfactants. Changes in liquid movement during extrusion, were influenced more by the level of liquid and the rate of extrusion, than by its composition. The level of liquid was also an important factor in terms of the force necessary to extrude the different formulations. For a given level of liquid, the glycerol solution tended to increase extrusion force, while the surfactant solutions tended to decrease the extrusion force. The liquid levels, particulate composition and rate of extrusion were important in terms of pellet size, size range, roundness and porosity. The low level of liquid involved produced elongated pellets. The wet formulations produced larger, agglomerated pellets with a wide particle size range and a higher porosity. The lowest porosity pellets were prepared from mixtures with no or a low barium sulphate content while the highest levels of porosity were found with equal parts MCC and barium sulphate. In general, for equivalent liquid contents, pellets made with the glycerol solution were more porous than those prepared with water while the opposite was true for pellets made with surfactants. Although the different liquids influenced water movements, they did not prevent the formation of high quality pellets by the process of extrusion/spheronization.

Algorithms↗
PubMed1998

Design of a 2 T multipole wiggler insertion device for the SRS.

Two new identical insertion devices have been designed for the Daresbury SRS. They are 2 T permanent-magnet multipole wigglers that will provide high flux in the X-ray region. This paper describes the magnetic and mechanical design of the arrays of steel pole pieces and permanent-magnet blocks. Also given is the engineering design of the support structure that will cope with the very large forces present while maintaining high levels of precision in gap setting and parallelism. The engineering design has been fully assessed using finite-element techniques to predict the deflections of critical parts of the structure. These two devices are due to be installed into the SRS by the end of 1998.

Journal Article↗
PubMed1996

Renal Na/Pi-cotransporters.

Two non-homologous proximal tubular apical Na/Pi-cotransport systems (type I and type II) have been identified thus far by expression cloning. Subsequent studies provided evidence that the type II Na/Pi-cotransporter represents a target for the physiological and pathophysiological regulation of proximal reabsorption of phosphate. The exact role of the type I Na/Pi-cotransporter in proximal Pi-reabsorption and eventually also in the renal handling of other substrates, such as organic anions, is currently less clear and needs further investigation. Evidence was obtained that acute changes of brush border membrane Na/Pi-cotransport involves endo- and exocytic movement of type II Na/Pi-cotransporters. In particular, we elucidated if and how phosphorylation reactions are involved and defined the intracellular structures of the endo/exocytic apparatus involved. At the level of the gene it will be necessary to elucidate its organization in order to understand the mechanisms involved in chronic regulations of Na/Pi-cotransport related to the type II Na/Pi-cotransporter. Furthermore, for structural investigations of these integral membrane proteins, they have to be isolated in sufficient quantities. Thus far the type II cotransporter (NaPi-2) has been expressed in Sf9 insect cells [20], which may eventually allow a purification of this protein.

Animals↗
PubMed1996

Taking the problem oriented medical record forward.

The problem oriented medical record (POMR) has proved to be very successful in providing a structure that helps doctors record their notes about patients, and view those notes subsequently in a manner that quickly gives them a good understanding of that patients history. This approach has been validated by the American Institute of Medicine. With the increased use of computer systems that implement the POMR by doctors, the limitations of this structure have become apparent, and there is clearly scope for developing the model further to improve the quality of the data recorded, and adding meaning to it. This paper describes some of the limitations of the POMR, and discusses a number of areas in which it may be extended. Crucially, this is done in a manner which is both implementable, and usable. The extensions explored include some types of entity including encounters, episodes and subproblems; and an alternative view-the Timeline. The terminology used for the extensions is clarified. Mechanisms by which these extensions have been implemented are described. Ways in which systems can manage these extensions automatically are suggested. Such implementations are constrained by the need not to allow the demands of the computer to intrude into the patient encounter. They are also constrained by the requirements for reporting by professional and governmental institutions, and by what is pragmatically feasible in software and hardware.

Computer Systems↗
PubMed1995

Expression of parathyroid hormone receptors in MDCK and LLC-PK1 cells.

Parathyroid hormone (PTH) inhibits renal proximal tubular phosphate (Pi) and bicarbonate reabsorption by regulating the activity of apical Na/Pi cotransport and Na/H exchange. Two renal epithelial cell lines ["proximal tubular", LLC-PK1; "distal tubular", Madin-Darby canine kidney, (MDCK) cells] were stably transfected with complementary deoxyribonucleic acids (cDNAs) encoding a cloned PTH receptor in order to examine the polarity of transfected receptor function and whether or not intrinsic Pi transport is regulated by the transfected PTH receptor. The receptors are functionally coupled to the stimulation of adenosine 3':5' cyclic monophosphate (cAMP) production at both cell surfaces in LLC-PK1 cells, whereas this response is primarily limited to the basolateral surface in MDCK cells. Immunocytochemistry suggests an apical and basolateral localization of the transfected PTH receptor in LLC-PK1 cells and only a basolateral localization in MDCK cells. PTH activation of the transfected receptors is not coupled to the regulation of intrinsic Pi transport in either LLC-PK1 or MDCK cells.

Adenylyl Cyclases↗
PubMed1995

Protein kinase C consensus sites and the regulation of renal Na/Pi-cotransport (NaPi-2) expressed in XENOPUS laevis oocytes.

Renal brush border membrane sodium/phosphate (Na/Pi)-cotransport activity is inhibited by hormonal mechanisms involving activation of protein kinases A and C. The recently cloned rat renal Na/Pi-cotransporter (NaPi-2) contains several protein kinase C but no protein kinase A consensus sites [17, 20]. In the present study we have expressed wild type and polymutant (protein kinase C consensus sites removed) NaPi-2-transporters in Xenopus laevis oocytes. The expression of transport function as well as the basic transport properties were unaffected by the removal of the consensus sites. Pharmacological activation of protein kinase C with phorbol 12,13-didecanoate (PDD) led to a time-dependent inhibition of expressed wild type Na/Pi-cotransport function; simultaneous exposure to staurosporine (0.3) prevented the PDD induced (50 nM) inhibition. The kinase-C-mediated inhibition was not prevented by the removal of the protein kinase C consensus sites. Pharmacological activation of protein kinase A (dibutyryl adenosine 3':5':cyclic monophosphate (cAMP)/forskolin) had no effect on wild type NaPi-2-induced oocyte Na/Pi-cotransport. It is concluded that the protein-kinase-C-mediated regulation of expressed Na/Pi-cotransport does not involve the predicted consensus sites. The involvement of "cryptic" phosphorylation sites and/or of a phosphorylated "regulatory" protein is discussed.

Amino Acid Sequence↗
PubMed1994

Role of N-linked glycosylation in rat renal Na/Pi-cotransport.

Our laboratory recently identified a sodium-dependent transport system for phosphate from rat kidney cortex (NaPi-2; Magagnin, S., Werner, A., Markovich, D., Sorribas, V., Stange, G., Biber, J., and Murer, H. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 5979-5983). In the present study we have investigated whether or not this cotransporter is glycosylated and the role of N-glycosylation in determining its function. Glycosidase digestion of the NaPi-2 protein from rat brush border membranes, in vitro translation studies, or oocyte expression of the NaPi-2 cRNA indicate that the mature protein is glycosylated. Glycosidase treatment reduces the size of the protein from approximately 70-110 kDa to approximately 60-65 kDa. We therefore used site-directed mutagenesis to identify which of the putative consensus sites for N-linked glycosylation are utilized in the mature NaPi-2 protein. Altering the nucleotide sequences encoding both of the Asn-298 and Asn-328 residues to Gln produced mutants that are completely devoid of glycosylation, whereas mutants in which each of these sites were mutated separately are glycosylated when expressed in oocytes. These results suggest that both of these sites are modified by N-linked glycosylation in the mature protein. Surface expression of glycosylated and unglycosylated NaPi-2-related proteins was documented by biotinylation experiments. In contrast to the wild-type (fully glycosylated) transporter, immunocytochemistry provides evidence for a partial intracellular localization of mutant unglycosylated cotransporters. Na/Pi cotransport was studied in oocytes expressing wild-type or mutagenized NaPi-2 proteins using tracer or electrophysiological techniques. Although the transport rates are lower (by a factor of 2-3) after expression of the unglycosylated NaPi-2 protein, the Pi transport characteristics (pH dependence, apparent affinity for Pi or Na+) are similar in oocytes expressing either wild-type or glycosylation-deficient proteins.

Animals↗
PubMed1994

Electrophysiological analysis of Na+/Pi cotransport mediated by a transporter cloned from rat kidney and expressed in Xenopus oocytes.

Phosphate (Pi) reabsorption in renal proximal tubules involves Na+/Pi cotransport across the brush border membrane; its transport rate is influenced by the Na(+)-coupled transport of other solutes as well as by pH. In the present study, we have expressed a cloned rat renal brush border membrane Na+/Pi cotransporter (NaPi-2) in Xenopus laevis oocytes and have analyzed its electrophysiologic properties in voltage- and current-clamp studies. Addition of Pi to Na(+)-containing superfusates resulted in a depolarization of the membrane potential and, in voltage-clamped oocytes, in an inward current (IP). An analysis of the Na+ and/or Pi concentration dependence of IP suggested a Na+/Pi stoichiometry of 3:1. IP was increased by increasing the pH of the superfusate; this phenomenon seems to be mainly related to a lowering of the affinity for Na+ interaction by increasing H+ concentration. The present data suggest that known properties of Pi handling at the tubular/membrane level are "directly" related to specific characteristics of the transport molecule (NaPi-2) involved.

Animals↗