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Biomedical subjects

J Owens

Publications and source records attributed to J Owens.

At least 55 records · Page 3Linked to original sources
PubMed1999

Television-viewing habits and sleep disturbance in school children.

OBJECTIVE: To investigate the relationship between specific television-viewing habits and both sleep habits and sleep disturbances in school children. METHODS: The parents of 495 children in grades kindergarten through fourth grade in three public elementary schools completed two retrospective survey questionnaires, one assessing their children's sleep behaviors and the other examining television-viewing habits of both the child and the family. Sleep domains assessed included bedtime resistance, sleep onset delay, sleep duration, anxiety around sleep, parasomnias, night wakings, and daytime sleepiness. Teachers from all three schools also completed daytime sleepiness questionnaires (N = 402) for the sample. RESULTS: Most of the television-viewing practices examined in this study were associated with at least one type of sleep disturbance. Despite overall close monitoring of television-viewing habits, one quarter of the parents reported the presence of a television set in the child's bedroom. The television-viewing habits associated most significantly with sleep disturbance were increased daily television viewing amounts and increased television viewing at bedtime, especially in the context of having a television set in the child's bedroom. The sleep domains that appeared to be affected most consistently by television were bedtime resistance, sleep onset delay, and anxiety around sleep, followed by shortened sleep duration. The parent's threshold for defining "problem sleep behavior" in their child was also important in determining the significance of the association between sleep disturbance and television-viewing habits. CONCLUSION: Health care practitioners should be aware of the potential negative impact of television viewing at bedtime. Parents should be questioned about their children's television-viewing habits as part of general screening for sleep disturbances and as part of anticipatory guidance in regards to healthy sleep habits in children. In particular, the presence of a television set in the child's bedroom may be a relatively underrecognized, but important, contributor to sleep problems in school children.

Analysis of Variance↗
PubMed1998

[3H](+)-7-OH-DPAT and [3H]pramipexole binding in the striatum and nucleus accumbens of Sprague-Dawley and Fischer-344 rats.

The binding of the D2-like agonists, (+)-7-hydroxy-N,N-di-n-[3H]propyl-2-aminotetralin (7-OH-DPAT) and [3H]pramipexole (2-amino-4,5,6-tetrahydro-6-propylaminobenzthiazole; MIRAPEX) were determined in membranes from adult male Sprague-Dawley and Fischer-344 rats. Saturation analysis, which optimized binding to D3 receptors, revealed 3-6 fold differences in Bmax values between the two radioligands with no change in affinity. [3H](+)7-OH-DPAT labeled 41.4+/-4.1 to 61.8+/-3.0 fmol/mg protein in nucleus accumbens and striatal homogenates, yet [3H]pramipexole labeled only 7.0+/-1.2 to 18.9+/-5.3 fmol/mg protein. Regional differences with both radioligands were observed in Fischer-344 rats; the striatum exhibited a 52%-69% greater density of sites in comparison to the nucleus accumbens. These data suggest that D3 receptor density can vary significantly between animal strains depending on the radioligand used, and [3H]pramipexole identifies a different ratio of sites in the striatum and nucleus accumbens compared to [3H](+)7-OH-DPAT.

Animals↗
PubMed1998

Differential cytotoxicity of [123I]IUdR, [125I]IUdR and [131I]IUdR to human glioma cells in monolayer or spheroid culture: effect of proliferative heterogeneity and radiation cross-fire.

Radioiodinated iododeoxyuridine (IUdR) is a novel, cycle-specific agent that has potential for the treatment of residual malignant glioma after surgery. As only cells in S-phase incorporate IUdR into DNA, a major limitation to this therapy is likely to be proliferative heterogeneity of the tumour cell population. Using a clonogenic end point, we have compared the toxicities of three radioiodoanalogues of IUdR--[123I]IUdR, [125I]IUdR and [131I]IUdR--to the human glioma cell line UVW, cultured as monolayers in the exponential and the plateau phase of growth and as multicellular spheroids. Monolayers treated in the exponential growth phase were most efficiently sterilized by [125I]IUdR (concentration resulting in 37% survival (C37) = 2.36 kBq ml(-1)), while [123I]IUdR and [131I]IUdR were less effective eradicators of clonogens (C37 = 9.75 and 18.9 kBq ml(-1) respectively). Plateau-phase monolayer cultures were marginally more susceptible to treatment with [123I]IUdR and [125I]IUdR (40% clonogenic survival) than [131I]IUdR (60% clonogenic survival). In cells derived from glioma spheroids, both [125I]IUdR and [123I]IUdR were again more effective than [131I]IUdR at concentrations up to and including 20 kBq ml(-1). However, the survival curve for [131I]IUdR crossed the curves for the other agents, resulting in lower survival for [131I]IUdR than [123I]IUdR and [125I]IUdR at concentrations of 40 kBq ml(-1) and higher, the clonogenic survival values at 100 kBq ml(-1) were 13%, 45% and 28% respectively. It was concluded that IUdR incorporating the Auger electron emitters 123I and 125I killed only cells that were in S-phase during the period of incubation with the radiopharmaceutical, whereas the superior toxicity to clonogenic cells in spheroids of [131I]IUdR at higher concentration was due to cross-fire beta-irradiation. These findings suggest that [131I]IUdR or combinations of [131I]IUdR and [123I]IUdR or [125I]IUdR may be more effective than Auger electron emitters alone for the treatment of residual glioma, if proliferative heterogeneity exists.

Cell Division↗
PubMed1998

'It comes together at the end': the impact of a one-year subject in Nursing Inquiry on philosophies of nursing.

This paper reframes an interpretive study as critical inquiry as the researchers interrogate their roles and authority in the 'reading' of what is valued as reflective. Working from data collected in written philosophies and interviews within the context of a one-year subject aimed at developing reflective practice and an appreciation of ways of knowing, this paper examines the change in philosophies of nursing perceived by three university-based educators and their students. The study reveals a growing appreciation of the complexity of nursing but a limited consideration of the dialectic of critical theorising and everyday engagement necessary to critical reflection and reconstruction of action. More importantly, the process of research collaboration raises questions of the soul-searching necessary for university educators to act against the institutionalised political context that determines what is seen to be of value in student learning.

Education, Nursing, Baccalaureate↗
PubMed1998

A split-mouth placebo-controlled study to determine the effect of amorphous calcium phosphate in the treatment of dentine hypersensitivity.

Many treatments for dentine hypersensitivity are formulated to directly or indirectly occlude the open dentinal tubules associated with the condition. Combining solutions of calcium chloride and potassium phosphate can result in the precipitation of amorphous calcium phosphate. Such a system applied to exposed dentine could occlude dentinal tubules and reduce sensitivity. The aims of this study using a placebo control were to assess the therapeutic value of amorphous calcium phosphate in dentine hypersensitivity and provide further information on the apparently natural improvement in the condition frequently observed in clinical trials. 38 subjects with dentine hypersensitivity affecting 1 tooth in each left and right sides of the jaws were recruited into this split mouth, randomised, double-blind study. At baseline, sensitivity was scored by the subjects on a 0-10 visual apologue scale after tactile, cool and cold water and evaporative stimulation of the test teeth. Active and control, water, solutions were then applied by a 2nd clinician. After 24 h, subjects returned for rescoring. On days 7 and 14, subjects were again rescored and the treatments reapplied. Further follow-up appointments for rescoring were on days 21, 28, 56 and 84. Plaque scores also were recorded from test teeth at each visit. Overall sensitivity decreased considerably and to a similar degree in test and control teeth with no consistent significant treatment difference. Plaque scores also decreased through the study period. It is concluded that either the amorphous calcium phosphate was without therapeutic effect or the activity was masked by the placebo response in the control teeth.

Administration, Topical↗
PubMed1998

Sleep and daytime behavior in children with obstructive sleep apnea and behavioral sleep disorders.

OBJECTIVE: The purpose of this study was: 1) to examine both bedtime sleep behaviors and daytime behaviors associated with daytime sleepiness in a group of children with a primary medical sleep disorder (obstructive sleep apnea syndrome [OSAS]) compared with a group of children with a primary behavioral sleep disorder (BSD) (limit setting sleep disorder or sleep onset association disorder); and 2) to investigate the impact of a comorbid BSD on sleep and daytime behavioral consequences of OSAS. METHODS: Children referred to a pediatric sleep disorders clinic during a 3-year period with a primary diagnosis of either polysomnographically-confirmed OSAS (n = 100) or a BSD (n = 52) were compared on several parent report measures assessing the following domains: symptoms of sleep disordered breathing, other sleep behaviors (primarily parasomnias), bedtime behaviors, and externalizing daytime behavior problems. The OSAS sample was then divided into a pure OSAS group (n = 78) and an OSAS plus a behavioral sleep diagnosis group (n = 22) based on the presence or absence of delayed sleep onset and/or prolonged nightwakings and compared on the parent-report symptom domains. RESULTS: Almost one-quarter of the OSAS group had clinically significant behavioral sleep problems, primarily bedtime resistance, in addition to OSAS. Bedtime resistance was associated with a significantly shortened sleep duration in both the BSD and OSAS-BSD groups. Although the OSAS-BSD group had less severe disease, as defined by polysomnographic variables, than the pure OSAS group, they were rated by their parents as having more daytime externalizing behavior problems associated with daytime sleepiness. CONCLUSIONS: The results of this study suggest that evaluation for comorbid BSD should be done in all children presenting with symptoms of OSAS. The coexistence of such BSDs may contribute significantly to sleep deprivation, and thus to behavioral manifestations of daytime sleepiness in these children.

Child↗
PubMed1997

Leadership. The personal touch.

The government is likely to move from a centralised corporatist form of governance to a more collaborative approach. This will require chief executives to rely on a style of leadership which derives more from personal influence than positional forms of power. It may be time to discuss the future of politically appointed chairs and whether the chief executive should be the sole local leader. The government's commitment to delegating power to regional tiers is likely to have a major impact on the nature of leadership in the NHS.

Administrative Personnel↗
PubMed1997

Interleukin-18 (interferon-gamma-inducing factor) is produced by osteoblasts and acts via granulocyte/macrophage colony-stimulating factor and not via interferon-gamma to inhibit osteoclast formation.

We have established by differential display polymerase chain reaction of mRNA that interleukin (IL)-18 is expressed by osteoblastic stromal cells. The stromal cell populations used for comparison differed in their ability to promote osteoclast-like multinucleated cell (OCL) formation. mRNA for IL-18 was found to be expressed in greater abundance in lines that were unable to support OCL formation than in supportive cells. Recombinant IL-18 was found to inhibit OCL formation in cocultures of osteoblasts and hemopoietic cells of spleen or bone marrow origin. IL-18 inhibited OCL formation in the presence of osteoclastogenic agents including 1alpha,25-dihydroxyvitamin D3, prostaglandin E2, parathyroid hormone, IL-1, and IL-11. The inhibitory effect of IL-18 was limited to the early phase of the cocultures, which coincides with proliferation of hemopoietic precursors. IL-18 has been reported to induce interferon-gamma (IFN-gamma) and granulocyte/macrophage colony-stimulating factor (GM-CSF) production in T cells, and both agents also inhibit OCL formation in vitro. Neutralizing antibodies to GM-CSF were able to rescue IL-18 inhibition of OCL formation, whereas neutralizing antibodies to IFN-gamma did not. In cocultures with osteoblasts and spleen cells from IFN-gamma receptor type II-deficient mice, IL-18 was found to inhibit OCL formation, indicating that IL-18 acted independently of IFN-gamma production: IFN-gamma had no effect in these cocultures. Additionally, in cocultures in which spleen cells were derived from receptor-deficient mice and osteoblasts were from wild-type mice and vice versa, we identified that the target cells for IFN-gamma inhibition of OCL formation were the hemopoietic cells. The work provides evidence that IL-18 is expressed by osteoblasts and inhibits OCL formation via GM-CSF production and not via IFN-gamma production.

Animals↗
PubMed1997

Acute and chronic effects of hypoxia on the developing hippocampus.

Perinatal hypoxia is associated with both seizures arising acutely and the subsequent development of temporal lobe epilepsy (as determined retrospectively). We therefore attempted to identify acute and chronic morphological and/or electrophysiological hippocampal pathologies associated with experimentally induced hypoxia in immature rats. Pups were exposed to 15 minutes of hypoxia on 3 successive days (starting on postnatal day 8; P8), or to 60 minutes of hypoxia on P10 with either one or multiple hypoxia-induced seizures. For animals experiencing multiple seizures, flurothyl seizure threshold was significantly lower than that of controls at 60 to 80 days, but not at 10 days, after hypoxia. Acutely, there was a treatment-related increase in the number and the density of pyknotic dentate and hilar neurons, in particular in animals experiencing multiple seizures. However, 60 to 80 days after the multiple-seizure protocol, the number of dentate and hilar neurons did not differ between control and experimental animals. Electrophysiological measures of pyramidal cell properties showed no striking difference between experimental and control animals at any time point. These results indicate that early postnatal hypoxia and hypoxia-induced seizure episodes decrease seizure threshold in the adult but produce minimal acute or chronic morphological or functional changes in the hippocampus.

Animals↗
PubMed1997

First SPET images of glutamate (NMDA) receptor activation in vivo in cerebral ischaemia.

This report describes the initial clinical assessment of (+)-3-[123I]Iodo-MK-801 and its potential to provide single photon emission tomographic (SPET) images in vivo of NMDA receptor activation during cerebral ischaemia. Multiple SPET images were obtained in the 120 min after the administration of 150 MBq of (+)-3-[123I]Iodo-MK-801 to five patients with cerebral ischaemia (due to cerebral haemorrhages) and to five normal volunteers. In normal subjects, (+)-3-[123I]Iodo-MK-801 has a rapid uptake into the brain. The tracer has a high non-specific retention in the central nervous system due to its lipophilicity, which was made evident by the retention of tracer in the cerebellum and white matter (brain areas with few NMDA receptors). In all patients with cerebral haemorrhages, the initial uptake of (+)-3-[123I]Iodo-MK-801 into the ipsilateral hemisphere was markedly reduced, consistent with a reduced level of cerebral blood flow. In two of five patients, relatively increased tracer retention at later time points (60-120 min after tracer administration) could be seen in cortical areas adjacent to the site of the haemorrhage, consistent with activated NMDA receptors. In three of the patients, no relatively enhanced tracer retention could be identified. Using (+)-3-[123I]Iodo-MK-801, it may be possible to image excessive glutamate (NMDA) receptor activation during an ischaemic episode in living human patients. The utility of (+)-3-[123I]Iodo-MK-801 as a SPET ligand for assessing modest alterations in NMDA receptor activity may ultimately be limited by its lipophilicity and consequent high non-specific binding.

Aged↗
PubMed1997

A short-term clinical study design to investigate the chemical plaque inhibitory properties of mouthrinses when used as adjuncts to toothpastes: applied to chlorhexidine.

The removal of plaque by toothbrushing with toothpaste is the most common form of plaque control in the developed world. However, the use of chemical adjuncts such as mouthrinses is increasing. In practice mouthrinses and toothpaste are used together, however, in many clinical trials, employed to assess mouthrinse activity, toothpaste use is suspended. This fails to measure the effect of chemical interactions which are known to occur between toothpaste ingredients and mouthrinses. The objective of this trial was to develop a methodology which would assess the adjunctive chemical plaque inhibitory action of mouthrinses, when used with toothpaste but without the indeterminate variable of toothbrushing. The study was a single blind, randomised, 7-way crossover design, based on a variation of a 4 day plaque regrowth model. The 2 x daily rinsing regimens produced increasing plaque scores in the following order: (1) water/chlorhexidine, (2) chlorhexidine/water, (3) chlorhexidine/toothpaste slurry, (4) toothpaste slurry/chlorhexidine, (5) water/toothpaste slurry, (6) toothpaste slurry/water, (7) water/water. Chlorhexidine and water or chlorhexidine and toothpaste slurry combinations produced significantly lower plaque scores than water alone. Slurry and water combinations resulted in less plaque than water alone, but differences were not significant. Toothpaste slurry and chlorhexidine produced significantly increased plaque scores compared to chlorhexidine and water. The study suggests that, outside the Hawthorne effect, chlorhexidine rinses would be less effective in reducing plaque when used with toothpaste than when used alone. The methodology could be employed as a screening tool for the evaluation of mouthrinses expected to be used as adjuncts to normal oral hygiene methods. The same could be used to optimise oral hygiene regimens which include the use of mouthrinses.

Adult↗
PubMed1997

An 18-week home-use study comparing the oral hygiene and gingival health benefits of triclosan and fluoride toothpastes.

Several triclosan and stannous fluoride toothpastes have been shown to have plaque inhibitory and more particularly gingival health benefits when compared to minus active controls. There have been relatively few studies to compare such products with conventional fluoride toothpastes in home use. The aim of this study was to compare the relative gingival health benefits of a triclosan/zinc citrate, triclosan/copolymer, stannous fluoride and conventional fluoride toothpastes in a home use study. The study was a double blind, parallel design with a total 143 healthy dentate volunteers (41 male, 102 female) who toothbrushed 2x daily with 1 of 4 toothpastes over an 18 week period. At the beginning of the trial, each volunteer was scored for plaque and gingivitis and then received a thorough prophylaxis. Each volunteer was allocated a toothpaste according to a predetermined randomisation scheme. The volunteers were then re-examined after 6, 12 and 18 weeks. No other oral hygiene products were used during this period. The results showed no statistically significant treatment differences between products for the gingival index throughout the 18 week-trial. No statistically significant treatment effects between products for plaque index were found at 6 or 18 weeks. However, a small but statistically significant treatment effect for plaque index was seen at 12 weeks in favour of the triclosan/copolymer toothpaste compared to the stannous fluoride and conventional fluoride toothpastes, this difference had disappeared by the 18 week examination. All volunteers oral hygiene and gingivitis scores improved after the baseline examination, and this improvement continued throughout the trial. This is a feature of nearly all toothbrushing studies and can be attributed to the initial prophylaxis and the Hawthorne phenomenon. Such phenomena, noted in home use clinical trials, may mask the efficacy of proven antiplaque formulations.

Adolescent↗
PubMed1997

A comparison of triclosan and stannous fluoride toothpastes for inhibition of plaque regrowth. A crossover study designed to assess carry over.

Some triclosan and stannous fluoride toothpastes have been shown effective in reducing plaque and more particularly gingivitis in home use studies. There have been few comparisons of such products for their chemical plaque inhibitory action divorced from the indeterminate variable of toothbrushing. This study was a randomised, single-blind, cross-over comparison of 4 products, in a 4-day plaque regrowth design, balanced for residual effects and involving 12 healthy dentate subjects. The test agents were a stannous fluoride toothpaste, a triclosan/copolymer toothpaste, a triclosan/zinc citrate toothpaste and water. On day 1 of each study period, subjects were rendered plaque free. For the following 4 days, each subject suspended normal toothcleaning and rinsed 2 x daily with the allocated treatment for 60 s under supervision. On day 5, plaque was scored by index. Washout periods of 2 1/2 days brushing with water alone, followed each treatment period. Pseudo treatment periods of 4 days, involving 2 x daily rinsing with water in the absence of toothbrushing, followed the normal washouts after the stannous fluoride and triclosan/zinc citrate treatments, giving a total of 6 treatment periods. This design permitted analyses for 1st-order-carry-over. Intention to treat analyses revealed all toothpastes were more effective than water but that there were no differences between the active treatments. Per protocol analysis gave essentially similar findings except that the difference in plaque in favour of the triclosan/zinc citrate toothpaste over water did not reach significance. There was no evidence of 1st-order-carry-over effects for the stannous fluoride or triclosan/zinc citrate toothpastes. Consistent with other studies it appears that stannous fluoride and triclosan can be formulated into toothpaste vehicles to provide plaque inhibitory effects.

Adult↗
PubMed1997

Incidence of parasomnias in children with obstructive sleep apnea.

The incidence of parent-reported parasomnias in children with obstructive sleep apnea (OSA) is increased in comparison with a normative age-matched sample of children but is not higher than that for a similar clinical sample of children with a diagnosed behavioral sleep disorder.

Child↗
PubMed1996

Wild-type p53 transgenic mice exhibit altered differentiation of the ureteric bud and possess small kidneys.

Transgenic mice expressing wild-type murine p53 under the control of the mouse mammary tumor virus long terminal repeat (MMTV LTR) undergo progressive renal failure due to abnormal kidney development. Similar phenotypes are observed in two transgenic lines that express wild-type p53 within the ureteric bud but not in transgenic animals expressing a dominant-negative p53 mutant allele. Defective differentiation of the ureteric bud, as evidenced by altered marker expression during development, accompanies expression of the p53 transgene. At E17.5-18.5, metanephric mesenchymal cells undergo high rates of apoptosis, and fewer cells than normal are converted to tubular epithelium. As a result, p53 transgenic kidneys grow to only half of their expected size and contain about half of the normal number of nephrons, with compensatory hypertrophy of the glomeruli. In this setting, rather than arrest the cell cycle or induce apoptosis directly, abnormally high levels of wild-type p53 appear to alter cellular differentiation in embryonic ureteric buds and cause secondary effects (apoptosis and inefficient conversion to epithelium) in the adjacent undifferentiated mesenchyme.

Animals↗