Biomedical subjects

S Turner

Publications and source records attributed to S Turner.

At least 109 records · Page 6Linked to original sources

PubMed1997

Influence of Ringer's solution on creep resistance of hydroxyapatite reinforced polyethylene composites.

In vitro creep studies of polyethylene, both unfilled and filled with hydroxyapatite at 0.20 and 0.40 volume fraction, have been performed. The samples were immersed in Ringer's solution at 37 degrees C for 1, 7, 30, 90 and 150 days prior to isochronous and creep tests in the same condition. The creep properties of unfilled polyethylene is unaffected by the immersion, but the isochronous modulus and the creep resistance of filled polyethylene were reduced. The effect increased with increasing volume fraction and time of immersion. This reduction is related to the penetration of the solution into the material, softening the interface.

Journal Article↗

PubMed1997

Genetic modification of the phenotypes produced by amyloid precursor protein overexpression in transgenic mice.

Overexpression of Alzheimer amyloid precursor protein (APP) produces dramatically different phenotypes in transgenic mice depending on the genetic background. For example, concentrations of APP that produce amyloid plaques in outbred transgenic lines are lethal for inbred FVB/N or C57BL/6J mice. Expression of SOD1 transgenes is protective, suggesting involvement of oxidative damage in premature death, but ablation of Apoe had no significant effect. In contrast, FGF2 transgene overexpression enhances the lethal effects of APP. Differential survival does not appear to reflect genetic differences in APP processing, but rather host responses to APP or its derivatives.

Alleles↗

PubMed1997

Practice parameters for the psychiatric assessment of infants and toddlers (0-36 months). American Academy of Child and Adolescent Psychiatry.

These practice parameters describe the psychiatric assessment of infants and toddlers (0-36 months) and support the growth of infant and toddler psychiatry, a rapidly developing field. Infants and toddlers are brought to clinical attention because of concerns about emotional, behavioral, relational, or developmental difficulties. It is axiomatic that the infant or toddler must be understood, evaluated, and treated within the context of the family. A perspective that is developmental, relational, and multidimensional and that borrows from the knowledge of multiple disciplines is essential. Collaborative efforts support the urgent need and incomparable opportunity to understand and to intervene early and preventively with young children and their families.

Child Psychiatry↗

PubMed1997

Measurement of hepatic Ra UDP-glucose in vivo in rats: relation to glycogen deposition and labeling patterns.

We previously described an isotopic method for quantifying the rate of appearance of hepatic UDP-glucose (Ra UDP-Glc) and the direct entry of glucose into hepatic UDP-Glc in humans. Here, the method is tested in depth in rats. The basic principles are that dilution of labeled galactose in hepatic UDP-Glc, sampled noninvasively by the xenobiotic glucuronate (GlcUA) method, reveals Ra UDP-Glc. First, labeling patterns in secreted acetaminophen-GlcUA were compared with hepatic glycogen and plasma glucose by use of mass isotopomer distribution analysis from [2-(13)C]glycerol. Labeling was consistent with common precursor pools of glucose 6-phosphate and triose-phosphate for all end products studied in fasted and in intravenous glucose- and fructose-infused states. Next, [1-(3)H]galactose was administered. After a 24-h fast, Ra UDP-Glc was 25.0 +/- 1.7 mumol.kg body wt-1.min-1 and rose to 57.7 and 72.7 mumol.kg-1.min-1 at intravenous glucose infusion rates of 111 and 167-194 mumol.kg-1.min-1, respectively. Liver glycogen deposition correlated closely with Ra UDP-Glc (R2 = 0.76), although the turnover value was approximately 50% higher than the net deposition rate. In conclusion, the turnover of an intrahepatic metabolite, UDP-Glc, can be measured noninvasively, and Ra UDP-Glc correlates with liver glycogen deposition in rats.

Animals↗

PubMed1997

Altered fluxes responsible for reduced hepatic glucose production and gluconeogenesis by exogenous glucose in rats.

The net release of glucose from the liver, or hepatic glucose production (HGP), and apparent gluconeogenesis (GNG) are reduced by exogenous glucose. We investigated the changes in metabolic fluxes responsible. Flux through the hepatic GNG pathway was quantified by mass isotopomer distribution analysis (MIDA) from [2-13C]glycerol. Unidirectional flux across hepatic glucose-6-phosphatase (G-6-Pase), or total hepatic glucose output (THGO), and hepatic glucose cycling (HGC) were also measured by using glucuronate (GlcUA) to correct for glucose 6-phosphate (G-6-P) labeling. Infusion of glucose (15-30 mg.kg-1.min-1 iv) to 24 h-fasted rats caused two important metabolic alterations. First was a significant increase in hepatic glucose uptake and HGC: > 60% of THGO was from HGC. Second, although flux through hepatic G-6-P increased (from 15.7 to 17.7-22.7 mg.kg-1.min-1), the partitioning of G-6-P flux changed markedly [from 30-35% to 55-60% entering UDP-glucose (UDP-Glc), P < 0.01]. Total flux through the GNG pathway remained active during intravenous glucose, but increased partitioning into UDP-Glc lowered GNG flux plasma glucose by 50%. In summary, the suppression of HGP and GNG flux into glucose is not primarily due to reduced carbon flow through hepatic G-6-Pase or the hepatic GNG pathway. THGO persists, but hepatic G-6-P is derived increasingly from plasma glucose, and flow through GNG persists, but the partitioning coefficient of G-6-P into UDP-Glc doubles. These adjustments permit net HGP to fall despite increased total production of hepatic G-6-P during administration of glucose.

Animals↗

PubMed1997

A study of the impact of Sun Awareness Week 1995.

We report a questionnaire-based survey of parents of schoolchildren to assess the impact of Sun Awareness Week, organized by the U.K. Skin Cancer Working Party, from 4 to 10 June 1995. A questionnaire was designed, pre-tested and modified. Nine hundred and eighty-nine patients of schoolchildren were approached before and after Sun Awareness Week at eight comprehensive primary schools and a children's clothes shop. Responses to the questionnaires were analysed in the following categories: total knowledge, sunscreen knowledge, melanoma risk factor knowledge, attitude, self-reported behaviour and awareness of the link between childhood sun exposure and cancer (link). A reasonable level of knowledge was demonstrated in the sample population. Significant improvements in attitude and behaviour scores were observed (P < 0.05). Three of the four link questions were significantly improved (P < 0.005). These results were not explained by differences in age, sex, or occupation between the before and after populations. Further national studies are needed to establish long-term benefits of such interventions.

Adolescent↗

PubMed1997

The role of soft tissues in the aetiology of malocclusion.

It is not always easy to discover the aetiology of malocclusion: only in about 5% of cases is a cause clearly identifiable. In this article, the various genetic, environmental and physical factors that may contribute to malocclusion are discussed.

Bite Force↗

PubMed1996

Distractive properties of a threaded interbody fusion device. An in vivo model.

STUDY DESIGN: Twenty sheep underwent anterior lumbar interbody fusions with either a threaded titanium interbody fusion device (cage, n = 8), autogenous iliac crest dowel graft (autograft, n = 6), or interbody decortication only (sham, n = 6). Two sheep had misplaced cages and were excluded. Sheep were killed after 6 months. OBJECTIVES: To determine whether this model is useful for examining the distractive and fixation properties of interbody fusion cages. SUMMARY OF BACKGROUND DATA: Interbody fusion cages are used in anterior lumbar interbody fusion procedures to provide immediate intersegmental fixation and to distract and preserve interbody height. The process of physiologic anchorage by bone ingrowth into such devices is under investigation. METHODS: Sheep were radiographed immediately after surgery and 2, 4, and 6 months after surgery. Interbody distraction and angulation were measured with a digital photo image analyzer at each time point. After the sheep were killed, stiffness to flexion, extension, and lateral bending moments were measured. Twelve untreated cadaver spines were also tested for comparison. RESULTS: After surgery, interbody distraction successfully occurred in cage and autograft-implanted sites. Loss of interbody height ensued, however, in all groups during the first 2 months. Percentage loss of height was lowest in cage sites. By 6 months, only cage sites remained distracted beyond normal. Fusions in all groups were stiffer than untreated spines. Autograft sites were stiffer than cage sites to lateral bending. Sham sites were stiffer than cage and autograft sites to flexion, but this likely resulted from complete intervertebral collapse. CONCLUSION: Despite early subsidence, interbody fusion cages successfully distracted and preserved interbody spaces. This model is useful for investigating methods of improving distraction and stabilization.

Animals↗

PubMed1996