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Biomedical subjects

B S Turner

Publications and source records attributed to B S Turner.

At least 19 recordsLinked to original sources
PubMed2001

The erosion of citizenship.

The Marshallian paradigm of social citizenship has been eroded because the social and economic conditions that supported postwar British welfare consensus have been transformed by economic and technological change. This article argues that effective entitlement was based on participation in work, war and reproduction, resulting in three types of social identity: worker-citizens, warrior-citizens and parent-citizens. The casualization of labour and the technological development of war have eroded work and war as routes to active citizenship. Social participation through reproduction remains important, despite massive changes to marriage and family as institutions. In fact the growth of new reproductive technologies have reinforced the normative dominance of marriage as a social relation. These rights of reproduction are described as 'reproductive citizenship'. The article also considers the role of voluntary associations in Third-Way strategies as sources of social cohesion in societies where social capital is in decline, and argues that the voluntary sector is increasingly driven by an economic logic of accumulation. With the erosion of national citizenship, Marshall's three forms of rights (legal, political and social) have been augmented by rights that are global, namely environmental, aboriginal and cultural rights. These are driven by global concerns about the relationship between environment, community and body such that the quest for social security has been replaced by concerns for ontological security.

Employment↗
PubMed2000

Tracheobronchial trauma associated with airway management in neonates.

Airway management procedures are an integral part of caring for the newborn infant with respiratory compromise. Concomitant with these interventions are latrogenic consequences that result in varying degrees of trauma to the tracheobronchial tree. Common interventions such as intubation, mechanical ventilation, use of heated and humidified gases, and endotracheal suctioning are discussed using research-based literature that evaluates the injury to the trachea and the mucociliary transport system.

Bronchi↗
PubMed2000

A historical perspective on the discovery of adenyl purines.

In 1929, Drury and Szent-Gyorgyi described the effects of a simple extract of heart muscle and other tissues on the mammalian heart. This extract was identified as adenylic acid and found to have profound effects on the cardiovascular system. The discovery and identification of adenyl purines and their effects on the cardiovascular system has now extended to other biological functions such as neurotransmission, neuromodulation, and endocrine/exocrine secretory functions and beyond. This review examines the history of the discovery and identification of the many roles played by adenyl purines in regulation of physiological homeostasis.

Adenine Nucleotides↗
PubMed1999

Cysteine-rich regions of pig gastric mucin contain von willebrand factor and cystine knot domains at the carboxyl terminal(1).

In order to sequence the cysteine-rich regions of pig gastric mucin (PGM), we used our previously identified pig gastric mucin clone PGM-2A to screen a pig stomach cDNA library and perform rapid amplification of cDNA ends to obtain two cysteine-rich clones, PGM-2X and PGM-Z13. PGM-2X has 1071 base pairs (bp) encoding 357 amino acids containing five serine-threonine-rich 16 amino acid tandem repeats, downstream from a cysteine-rich region similar to human and mouse MUC5AC. PGM-Z13 encodes the complete 3'-terminus of PGM and is composed of 3336 bp with a 2964 bp open reading frame encoding 988 amino acids with four serine-threonine-rich tandem repeats upstream from a cysteine-rich region similar to the carboxyl terminal regions of human and rat MUC5AC and human MUC5B. This region is homologous to von Willebrand factor C and D domains involved in acid induced polymerization, and to the carboxyl terminal cystine-knot domain of various mucins, TGF-beta, vWF and norrin, which is involved in dimerization. These newly sequenced cysteine-rich regions of pig gastric mucin may be critical for its gelation and for its observed increased viscosity induced by low pH.

Amino Acid Sequence↗
PubMed1999

pH-dependent conformational change of gastric mucin leads to sol-gel transition.

We present dynamic light scattering (DLS) and hydrophobic dye-binding data in an effort to elucidate a molecular mechanism for the ability of gastric mucin to form a gel at low pH, which is crucial to the barrier function of gastric mucus. DLS measurements of dilute mucin solutions were not indicative of intermolecular association, yet there was a steady fall in the measured diffusion coefficient with decreasing pH, suggesting an apparent increase in size. Taken together with the observed rise in depolarized scattering ratio with decreasing pH, these results suggest that gastric mucin undergoes a conformational change from a random coil at pH >/= 4 to an anisotropic, extended conformation at pH < 4. The increased binding of mucin to hydrophobic fluorescent with decreasing pH indicates that the change to an extended conformation is accompanied by exposure of hydrophobic binding sites. In concentrated mucin solutions, the structure factor S(q, t) derived from DLS measurements changed from a stretched exponential decay at pH 7 to a power-law decay at pH 2, which is characteristic of a sol-gel transition. We propose that the conformational change facilitates cross-links among mucin macromolecules through hydrophobic interactions at low pH, which in turn leads to a sol-gel transition when the mucin solution is sufficiently concentrated.

Animals↗
PubMed1999

Efficacy of saline vs heparin in maintaining 24-gauge intermittent intravenous catheters in a rabbit model.

PURPOSE: The purpose of this study was to compare saline and heparin flushes in 24-gauge i.v. catheters. DESIGN: A double-blind experiment in four recorded trials was conducted using a rabbit model. Twenty-four-gauge catheters were placed in both auricle veins, and all catheters were secured in the same manner. Ampicillin was infused into each ear at the same interval, with each ear randomized to receive either the heparin solution or the saline solution. SAMPLE: The subjects were ten white New Zealand rabbits. Data were collected on 76 catheter sites. MAIN OUTCOME VARIABLE: Patency for each catheter was measured in hours and evaluated based on presence of warmth, erythema, induration, leakage, or occlusion. RESULTS: There was no significant difference in the duration of patency of the catheters between the two groups.

Animals↗
PubMed1998

Dysregulation of proteoglycan production by intrahepatic biliary epithelial cells bearing defective (delta-f508) cystic fibrosis transmembrane conductance regulator.

Hepatic dysfunction in cystic fibrosis (CF) has been attributed to accumulation of viscous mucoid secretions in intrahepatic bile ducts. The purpose of our study was to compare glycoconjugate secretion by intrahepatic biliary epithelial (IBE) cells derived from normal livers and livers of CF patients with the delta F508 mutation of the cystic fibrosis transmembrane conductance regulator (CFTR). Confluent cells were incubated with 3H-glucosamine (GlcN) for 16 hours, and radiolabeled macromolecules were analyzed for the amount and type of glycoconjugates. Incorporation of 3H-GlcN into macromolecular glycoconjugates was two- to threefold higher in CF cells versus normals, as was uptake of 3H-Glcn into the cytoplasm of CF cells. Gel exclusion chromatography on Sepharose Cl 4B revealed that the secreted glycoconjugates from CF cells eluted entirely in the excluded fraction (molecular weight > 2 x 10(6)), while, in the normal cells, 60% of the glycoconjugates eluted as lower-molecular-weight species. The high-molecular-weight glycoconjugates in both CF and normal cells were identified as chondroitin sulfates, as evidenced by susceptibility to beta elimination, chondroitinase digestion, and amino acid composition. Western blotting of IBE cell secretions with a polyclonal antibody to chondroitin sulfate revealed proteoglycan bands at 100 and 210 kd. Our results indicate that secretion of chondroitin sulfate is markedly increased in CF biliary epithelium in vitro compared with non-CF cells. Increased uptake of precursor 3H-GlcN may contribute to enhanced glycosylation of chondroitin sulfate in CF cells.

Amino Acids↗
PubMed1998

Ageing and generational conflicts: a reply to Sarah Irwin.

In response to Sarah Irwin, the article develops a conflict model of inter-generational exchanges and treats generation as a neglected dimension of social stratification theory and research. Against Irwin's focus on individual attitudes from survey data towards intra-familial co-operation between generations, the article draws on public policy on dependency, legislation on retirement, superannuation and pensions, and stereotypes of the elderly to study inter-generational inequalities. Employing Pierre Bourdieu's distinction between cultural and economic capital, it considers the formation of generations around political events, shared culture and strategic advantage. Generational conflict is structurally organized around the tensions between early retirement, age-related competency, legislation on ageism, and youth unemployment. Given rapid and radical changes to the labour market, generational cohesion is an important dimension therefore of strategies of social closure.

Aged↗
PubMed1995

Isolation and characterization of cDNA clones encoding pig gastric mucin.

Polyclonal antibodies raised to deglycosylated pig gastric mucin were used to screen a cDNA library constructed with pig stomach mucosal mRNA. Immunocytochemistry indicated that the antibody recognizes intracellular and secreted mucin in surface mucous cells of pig gastric epithelium. A total of 70 clones producing proteins immunoreactive to this antibody were identified, two of which (PGM-2A,9B) were fully sequenced from both ends. Clone PGM-9B hybridized to a polydisperse mRNA (3-9 kb) from pig stomach, but not liver, intestine or spleen, nor to mRNA from human, mouse, rabbit or rat stomach. Sequence analysis indicated that PGM-9B encodes 33 tandem repeats of a 16-amino-acid consensus sequence rich in serine (46%) and threonine (17%). Using the restriction enzyme MwoI, which has a single target site in the repeat, it was demonstrated that PGM-9B consists entirely of this tandem repeat. Southern-blot analysis indicated that the repeat region is contained in a 20 kb HindIII-EcoRI fragment, and BamHI digestion suggested that most of the repeats are contained in a 10 kb fragment. In situ hybridization with an antisense probe to PGM-9B showed an intense signal in the entire gastric gland. Clone PGM-2A also contains the same repeat sequence as 9B, but, in addition, has a 64-amino-acid-long non-repeat region at its 5' end. Interestingly the non-repeat region of PGM-2A has five cysteine residues, the arrangement of which is identical with that reported for human intestinal mucin gene MUC2.

Amino Acid Sequence↗
PubMed1994

How to make research happen: working with staff.

Implementing a research project in a clinical nursing unit requires the researcher to gain cooperation and support from administration, physicians, and the nursing staff. In this article the site coordinators from the Transition of the Preterm Infant to an Open Crib research-utilization project share their strategies for generating support, energizing the staff nurses, assuring compliance with the study, resolving problems, and bringing the project to closure. Many of the strategies used can be applied to other research projects by nurse researchers interested in using clinical nursing units as research sites.

Clinical Nursing Research↗
PubMed1992

Viscous fingering of HCl through gastric mucin.

The HCl in the mammalian stomach is concentrated enough to digest the stomach itself, yet the gastric epithelium remains undamaged. One protective factor is gastric mucus, which forms a protective layer over the surface epithelium and acts as a diffusion barrier Bicarbonate ions secreted by the gastric epithelium are trapped in the mucus gel, establishing a gradient from pH 1-2 at the lumen to pH 6-7 at the cell surface. How does HCl, secreted at the base of gastric glands by parietal cells, traverse the mucus layer without acidifying it? Here we demonstrate that injection of HCl through solutions of pig gastric mucin produces viscous fingering patterns dependent on pH, mucin concentration and acid flow rate. Above pH 4, discrete fingers are observed, whereas below pH 4, HCl neither penetrates the mucin solution nor forms fingers. Our in vitro results suggest that HCl secreted by the gastric gland can penetrate the mucus gel layer (pH 5-7) through narrow fingers, whereas HCl in the lumen (pH 2) is prevented from diffusing back to the epithelium by the high viscosity of gastric mucus gel on the luminal side.

Animals↗
PubMed1991

Profound increase in viscosity and aggregation of pig gastric mucin at low pH.

Epithelial mucins are glycoproteins of very large molecular weight that provide viscoelastic and gel-forming properties to mucus, the jellylike protective layer covering epithelial organs. In the mammalian stomach the mucus gel layer protects the underlying epithelial cells from HCl in the lumen. We report here that pig gastric mucin undergoes a 100-fold increase in viscosity in vitro when pH is lowered from 7 to 2. Sedimentation velocity and dynamic light-scattering measurements revealed the formation of extremely large aggregates at low pH consistent with the observed increase in viscosity. Aggregation of mucin at low pH was prevented by increasing the ionic strength, suggesting the involvement of electrostatic interactions. Trypsin digestion and thiol reduction, but not enzymatic removal of neuraminic acid, prevented aggregation at low pH. This implies that the peptide core rather than the oligosaccharide side chains of the molecule is involved in the aggregation of mucin at low pH. Increased aggregation and viscosity at low pH were also observed in a solvent made to mimic the ionic composition of gastric juice, indicating the physiological relevance of our findings. Our observations suggest that one mechanism of gastric protection may be the ability of gastric mucin to undergo aggregation with a marked increase in viscosity at low pH.

Animals↗
PubMed1991

Endotracheal suctioning in adults with head injury.

The purpose of this study was to determine the method of endotracheal suctioning (ETS) that resulted in the least compromise to the cerebrovascular status of adult patients with severe head injuries. A two-group (two vs three ETS), two-protocol (100% tidal volume [VT] vs 135% VT) design was used. The dependent variables were mean intracranial pressure (MICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), heart rate (HR), and oxygen saturation (SaO2). By random assignment, 14 subjects were in the two-ETS group and 16 subjects were in the three-ETS group. Intracranial pressure response to ETS in these patients with head injury can be characterized as falling into three patterns: (1) a rise in baseline beginning with ETS and continuing throughout the ETS sequences; (2) intracranial pressure spiking during the suctioning component of the protocol; (3) a combination of both a rising baseline and spiking. There was a significant (p less than or equal to 0.001) increase from baseline for both two- and three-ETS groups with both hyperoxygenation protocols (100% VT vs 135% VT) for MICP, MAP, HR, and CPP. No significant difference was found for SaO2 for either of the protocols regardless of number of suction passes. No significant differences were found between two- and three-ETS groups for any of the dependent variables. All groups, however, regardless of number of suction passes, demonstrated a cumulative increase in MICP, MAP, and CPP with each consecutive suction sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Bile salts stimulate glycoprotein release by guinea pig gallbladder in vitro.

Alterations in the composition of bile during cholesterol gallstone formation appear to be responsible for increased release of gallbladder mucin, a potent cholesterol nucleating agent. We investigated the effects of bile salts on release of radiolabeled glycoproteins by explants of guinea pig gallbladder in organ culture. Bile salts, in concentrations of 1 to 5 mmol/L, caused a dose-dependent release of [3H]-glycoproteins with a range of potencies in this order: chenodeoxycholate greater than deoxycholate much greater than cholate greater than ursodeoxycholate = control. Chenodeoxycholate and deoxycholate were significantly more potent than cholate (p less than 0.0001). Unconjugated and taurine-conjugated bile salts were of similar potency. Bile salts also caused increased release of glycoproteins from explants of guinea pig gastric antrum and colon. The bile salts released after bile salt exposure included mucin and lower molecular weight glycoproteins from the gallbladder. Release of glycoproteins in response to bile salts was not inhibited by indomethacin, atropine or propranolol, nor was it dependent on extracellular calcium or microtubules. Glycoprotein release in response to bile salts was associated with membrane damage as indicated by a dose-dependent leakage of the cytoplasmic enzyme lactate dehydrogenase, although light microscopy did not reveal structural damage to epithelial cells. We conclude that hydrophobic bile salts stimulate gallbladder glycoprotein release in vitro by a detergent effect on the plasma membrane rather than by a receptor-mediated secretory pathway.

Animals↗
PubMed1990

Embryologic and physiologic basis of neonatal respiration.

Development of the respiratory system requires the integration of anatomic, physiologic, and biochemical factors. This process is described from 5 weeks gestation until establishment of respirations after birth.

Embryonic and Fetal Development↗