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Influence of dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and three dentin regions within a post space.

STATEMENT OF PROBLEM: Debonding is the most frequent failure encountered with translucent fiber posts and usually occurs along the post space dentin-adhesive interface. PURPOSE: The purpose of this study was to evaluate the effect of different dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and root dentin in different regions of the post space. MATERIAL AND METHODS: Forty maxillary canines with similar root lengths were selected, sectioned at the cemento-enamel junction, and the roots were endodontically treated. Following post space preparation, the roots were divided into 4 groups of 10 specimens each, and the post spaces were treated with 1 of 4 different dentin bonding agents: light-polymerized, single-bottle bonding agent Excite (Group EX); dual-polymerized, single-bottle bonding agent Excite DSC (Group EX-DSC); self-etching primer Clearfil Liner Bond 2V with a light-polymerized bonding agent, Bond A (Group CL-LC); or self-etching primer Clearfil Liner Bond 2V with a dual-polymerized bonding agent, Bond A+B (Group CL-DC). Translucent fiber posts (D.T. Light-Post), 2.2 mm in diameter, were luted (Panavia F) in each specimen after respective dentin bonding procedures. The roots were cut into 3-mm-thick sections, perpendicular to the long-axis in cervical, middle, and apical post space dentin. Push-out tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and bond strength values (MPa) were calculated by dividing the force at which bond failure occurred by the bonded area of the post. The data were analyzed with 1- and 2-way analysis of variance and Tukey multiple comparison tests (alpha=.05). Dentin adhesive bonding mechanisms in different regions of the post spaces were evaluated with a scanning electron microscope. RESULTS: The highest mean bond strength values were obtained for Group CL-LC (18.3 +/- 4.1 MPa). The dual-polymerized bonding agent resulted in significantly lower bond strength (P<.001) in combination with self-etching primer (Group CL-DC) (13.2 +/- 2.5 MPa). The light-polymerized and dual-polymerized single-bottle bonding agents provided similar bond strengths (12.7 +/- 5.0 for EX; 13.5 +/- 5.3 for EX-DSC). The regional bond strength values of single-bottle bonding agents were reduced significantly in apical post space dentin (P<.001). Self-etching primers did not demonstrate regional differences in post space dentin bonding and dense resin tags were apparent. CONCLUSION: Data suggests that the self-etching primer system used in this study was unaffected by the morphological variations in the post space dentin compared to the single-bottle bonding agents. Dual polymerization did not improve the bond strength values of the bonding agents tested.

Analysis of Variance↗

The relationship between access and quality of urban green space with population physical activity.

OBJECTIVES: This study examined the association between access to quality urban green space and levels of physical activity. STUDY DESIGN: A cross-sectional examination of the relationship between access to quality urban green space and level of recreational physical activity in 4950 middle-aged (40-70 years) respondents from the European Prospective Investigation into Cancer and Nutrition (EPIC), who resided in Norwich, UK. METHODS: Using geographic information systems (GIS), three measures of access to open green space were calculated based on distance only, distance and size of green space and distance, size and quality of green space. Multiple regression models were used to determine the relationship between the three indicators of access to open green space and level of recreational physical activity. RESULTS: There was no evidence of clear relationships between recreational activity and access to green spaces. Non-significant associations were apparent for all variables, and there was no evidence of a clear trend in regression coefficients across quartiles of access for either the distance, size adjusted, and quality and size-adjusted models. Furthermore, the neighbourhood measures of access to green spaces showed non-significant associations with recreational physical activity. CONCLUSIONS: Access to urban green spaces does not appear to be associated with population levels of recreational physical activity in our sample of middle-aged adults.

Adult↗

Avoiding the Space of Retzius During the Laparoscopic Burch Procedure

Although the structures apposed by a Burch colposuspension, the lateral vaginal fornix and Cooper's ligament, are approached surgically by opening the space of Retzius, neither actually lies in the space of Retzius but in the paravesical-paravaginal space. Cooper's ligament cannot be exposed adequately if the paravesical space is opened laparoscopically. Five primary Burch colposuspensions were performed without opening the space of Retzius, four with the uterus in place and one after a hysterectomy. Approaching the operation through the paravesical space has several advantages. A fixed anatomic landmark for the paravesical space is the umbilical ligament, and it can be easily identified laparoscopically. The paravesical space can be opened without risk of bladder injury. The urachus does not have to be divided. All the advantages of a transperitoneal approach are retained. Suture placement is greatly facilitated. Preliminary experience suggests that a laparoscopic Burch procedure can be carried out easily, quickly, and safely through the paravesical space, but this requires confirmation.

Journal Article↗

Dilated intercellular spaces as a marker of oesophageal damage: comparative results in gastro-oesophageal reflux disease with or without bile reflux.

BACKGROUND: The dilation of oesophageal intercellular spaces, clearly apparent in transmission electron microscopy images, is a marker of cellular damage induced by acid. AIM: To analyse the presence of dilated intercellular spaces and to quantify the scores in controls and in patients with gastro-oesophageal reflux disease or duodenal gastro-oesophageal reflux accompanied by erosive or non-erosive reflux disease. METHODS: Thirty-eight symptomatic patients with gastro-oesophageal reflux disease or duodenal gastro-oesophageal reflux and 12 asymptomatic controls, classified on the basis of pH-metry and bilimetry, underwent endoscopy. Six tissue biopsies were taken from the normal mucosa for light microscopy and transmission electron microscopy evaluation. Dilated intercellular spaces were measured on photomicrographs of the specimens (at least 100 transects were measured for each patient). RESULTS: Twenty-two patients with gastro-oesophageal reflux disease had normal macroscopic mucosa but, at histology, five patients with erosive gastro-oesophageal reflux disease had mild oesophagitis and one had moderate oesophagitis. Seven patients with duodenal gastro-oesophageal reflux had normal mucosa, whilst three with erosive duodenal gastro-oesophageal reflux had mild oesophagitis at histology. At transmission electron microscopy, all controls had dilated intercellular spaces of less than 1.69 microm. Each symptomatic patient had a mean dilated intercellular space value and a mean value of the maximum dilated intercellular space at least three or more times greater than that in controls (P < 0.001). No statistical differences were observed between erosive and non-erosive oesophagitis. CONCLUSIONS: The dilated intercellular space is an extremely sensitive marker of damage in gastro-oesophageal reflux disease, duodenal gastro-oesophageal reflux and non-erosive reflux disease, and serves as the most appropriate marker of damage evaluation in non-erosive reflux disease reported to date. A mean dilated intercellular space of 0.74 micro m provides a cut-off score for damage. No quantitative or qualitative differences in dilated intercellular space scores were found between pure and mixed acid reflux.

Adult↗

Microbial contamination of indoor air due to leakages from crawl space: a field study.

Mechanical exhaust ventilation system is typical in apartment buildings in Finland. In most buildings the base floor between the first floor apartments and crawl space is not air tight. As the apartments have lower pressure than the crawl space due to ventilation, contaminated air may flow from the crawl space to the apartments. The object of this study was to find out whether a potential air flow from crawl space has an influence on the indoor air quality. The results show that in most cases the concentration of fungal spores was clearly higher in the crawl space than inside the building. The size distribution of fungal spores depended on the fungal species. Correlation between the fungal spores in the crawl space and indoors varied with microbial species. Some species have sources inside the building, which confounds the possible relation between crawl pace and indoor concentrations. Some species, such as Acremonium, do not normally have a source indoors, but its concentration in the crawl space was elevated; our measurements showed also elevated concentrations of Acremonium in the air of the apartments. This consistent finding shows a clear linkage between fungal spores in the indoor air and crawl space. We conclude that a building with a crawl space and pressure difference over the base floor could be a potential risk for indoor air quality in the first floor apartments.

Air Microbiology↗

Crown allometry and growing space efficiency of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) in pure and mixed stands.

In pure and mixed stands of Norway spruce ( Picea abies [L.] Karst.) and European beech ( Fagus sylvatica L.) we have analyzed crown allometry and growing space efficiency at the tree level and have scaled this from tree level to stand level production. Allometry is quantified by the ratio A between the relative growth rates of laterally and vertically oriented tree dimensions. Efficiency parameters, EOC for efficiency in space occupation, EEX for efficiency in space exploitation, and EBI for efficiency in biomass investment, were evaluated, based on quantity and quality of growing space and were measured using crown size and competition index. The evaluation reveals why pure stands of spruce are preferred by foresters, even though the natural vegetation would be dominated by beech. Spruce occupies its share of resources intensively by means of tightly packed pillar-like crowns, whereas beech seizes resources extensively by means of a multi-layered, veil-like canopy. With a given relative biomass increment, beech achieves a 57 % higher increment in crown projection area and a 127 % higher increment in height due to its particular capacity of lateral and vertical expansion. Beech trees are approximately 60 % more efficient in space occupation than spruce trees, however, on average, they are about 70 % less efficient in space exploitation. As a vertical fast growing tree, spruce is efficient in space exploitation under constant conditions, but far more susceptible to disturbances and less well equipped to overcome them when compared with beech. Beech is weaker in terms of space exploitation, while being superior in space occupation, where it encircles competitors and fills gaps after disturbances, which is a successful long-term strategy. A mixture of the two species reduces stand level production by 24 % in comparison to a pure spruce stand, however, when considering enhanced stabilization of the whole stand and risk distribution in the long term, the mixed stand may exceed the production level of pure spruce stands. EEX reflects a strong ontogenetic drift and competition effect that should be considered when scaling from tree to stand level production.

Ecosystem↗

Dynamical and statistical effects of the intrinsic curvature of internal space of molecules.

The Hamilton dynamics of a molecule in a translationally and/or rotationally symmetric field is kept rigorously constrained in its phase space. The relevant dynamical laws should therefore be extracted from these constrained motions. An internal space that is induced by a projection of such a limited phase space onto configuration space is an intrinsically curved space even for a system of zero total angular momentum. In this paper we discuss the general effects of this curvedness on dynamics and structures of molecules in such a manner that is invariant with respect to the selection of coordinates. It is shown that the regular coordinate originally defined by Riemann is particularly useful to expose the curvature correction to the dynamics and statistical properties of molecules. These effects are significant both qualitatively and quantitatively and are studied in two aspects. One is the direct effect on dynamics: A trajectory receives a Lorentz-like force from the curved space as though it was placed in a magnetic field. The well-known problem of the trapping phenomenon at the transition state is analyzed from this point of view. By showing that the trapping force is explicitly described in terms of the curvature of the internal space, we clarify that the physical origin of the trapped motion is indeed originated from the curvature of the internal space and hence is not dependent of the selection of coordinate system. The other aspect is the effect of phase space volume arising from the curvedness: We formulate a general expression of the curvature correction of the classical density of states and extract its physical significance in the molecular geometry along with reaction rate in terms of the scalar curvature and volume loss (gain) due to the curvature. The transition state theory is reformulated from this point of view and it is applied to the structural transition of linear chain molecules in the so-called dihedral angle model. It is shown that the curvature effect becomes large roughly linearly with the size of molecule.

Journal Article↗

Physical space and cyberspace: how do they interrelate? A study of offline and online social interaction choice in Singapore.

This paper investigates if the new space created by cyberspace affects how we use old space--physical space--and how the range of physical space we have access to affects our urge to extend into cyberspace. To do this I polled young IT savvy people in land-scarce Singapore about the amount of physical space they had at their disposal--private space in terms of the size of their house and bedroom space, and public space in terms of how many public meeting areas they frequented. I attempted to see if there was a correlation between the amount of physical space they enjoyed and the amount of time they spent in cyberspace.

Adolescent↗

Floor Space Needs for Laboratory Mice: C56BL/6 Males in Solid-bottom Cages with Bedding.

Measures of performance, mortality, adrenal weights, plasma glucocorticoid concentration, and selected immune measures were collected in an attempt to define space needs of laboratory mice. Six replications of 3 C57BL/6 male mice per cage were examined while housed on bedding at 5, 10, 15, or 20 in(2) (32.2, 64.5, 96.8, or 129 cm(2)) per mouse. Body weights were not influenced by treatment; however, mice in smaller spaces (5 in(2) per mouse) consumed or wasted more feed and water than mice given greater space allowances. Mice given the least amount of space (5 in(2) per mouse) had greater lymphocyte proliferation in response to the T-cell mitogen PHA than mice given more space. Mice provided 10 in(2) per mouse had greater natural killer cytotoxicity than mice given greater or less space. Mouse mortality was greater as more space was provided. In contrast, adrenal weights and plasma glucocorticoid concentrations were progressively greater with lower space allowances. The National Research Council 1996 recommendation of 15 in(2) per mouse, for this strain and sex of mice, would result in greater mortality and reduced activity of some immune measures. Socially housed male C57BL/6 mice will benefit from less space than recommended by the National Research Council in 1996.

Journal Article↗

Joint space in radiologically normal knees.

Joint space loss is a characteristic feature of rheumatoid arthritis and osteoarthritis. It cannot be fully evaluated, however, without knowledge of the normal variability of joint space size. We have measured joint space size using digital image analysis in a population of radiologically normal individuals. Anteroposterior films of the knee were studied from 685 consecutive patients attending Casualty with unexplained knee pain or following trauma, but with no clinical or radiological evidence of arthritis. Results show that in a radiologically normal population, men have larger joint spaces than women and there is a steady decline in joint space size with age. We found no significant difference in joint space size between weight bearing and non-weight bearing women. There was also no difference in patients presenting with pain and those presenting following an injury. Normal joint space size was not related to height, weight or body mass index in a subgroup of 213 patients. We suggest that patients lose joint space with increasing age and eventually reach a 'pain threshold' at which symptoms of osteoarthritis occur. This explains the increase in joint symptoms in those who begin with smaller joint spaces; that is in women and in the elderly.

Adolescent↗

Stress radiographs after ankle fracture: the effect of ankle position and deltoid ligament status on medial clear space measurements.

OBJECTIVE: This study was designed to determine 1) how ankle position affects the medial clear space by using stress radiographs, 2) which medial clear space measurement, overall width or increase in width, better predicts deep deltoid ligament disruption after Weber type-B distal fibular fracture, and 3) what value of medial clear space is most predictive of deep deltoid ligament disruption after Weber type-B distal fibular fracture. DESIGN: Cadaveric fracture model. SETTING: Biomechanics laboratory. INTERVENTION: Fluoroscopic mortise views were taken of 6 fresh cadaveric ankles mounted in a fixture permitting both positioning in neutral flexion, dorsiflexion, and plantarflexion, and the application of internal and external rotational forces. After destabilizing the ankles according to the supination-external rotation mechanism of Lauge-Hansen, repeat radiographs were taken with the same combination of flexion and applied rotational stress. MAIN OUTCOME MEASURE: Radiographic measurements of medial clear space width and changes in medial clear space were made. RESULTS: A medial clear space of > or =5 mm on radiographs taken in dorsiflexion with an external rotational stress was most predictive of deep deltoid ligament transection after distal fibular fracture. In dorsiflexion-external rotation, medial clear spaces of > or =4 mm yielded lower specificity and positive predictive value, whereas > or =6 mm yielded lower sensitivity and negative predictive value. All other stress conditions and increases in medial clear space of 2 or 3 mm were less predictive. CONCLUSIONS: Ankle stress radiographs taken in dorsiflexion-external rotation were most predictive of deep deltoid ligament disruption after distal fibular fracture. Under this stress condition, a medial clear space of > or =5 mm was the most reliable predictor of deep deltoid ligament status.

Aged↗

Solutes in the free space of growing stem tissues.

The concentration of osmotically active solutes in the cell wall free space of young stem tissues was studied using a variety of extraction methods. When the intercellular air spaces of etiolated pea (Pisum sativum L.) internodes were perfused with distilled H(2)O, the resulting solution contained a solute concentration of about 70 milliosmoles per kilogram. A second procedure involving vacuum infiltration of segments followed by centrifugation to collect the free space solution gave similar results. Apical stem segments yielded free space extracts about twice as concentrated as those from basal portions of the stem. After correcting for dilution of the free space solution by the infiltrated water, the osmotic pressure of the undiluted free space in pea stem tissue was estimated to be 2.9 bars for apical segments, 1.8 bars for basal regions. These values may be somewhat overestimated due to solute efflux from intracellular pools during the extraction procedure. Similar results were obtained for stem regions of etiolated soybean (Glycine max [L.] Merr.) and cucumber (Cucumis sativus L.) seedlings.From measurements of the electrical conductivity and refractive index of free space extracts before and after ashing, it appears that 25% of the solutes are inorganic electrolytes and 75% are organic nonelectrolytes with an average size similar to that of glucose.A significant osmotic pressure in the wall space offers an explanation for the frequent observation that nontranspiring plants have negative water potentials. Calculations of hydraulic resistance from water potential data must take into account solutes in the free space, else ;apparent,' but unreal, changes in resistance may be calculated.

Journal Article↗

Role of endogenous cortisol in basal liquid clearance from distal air spaces in adult guinea-pigs.

1. We investigated the role of endogenous cortisol in the modulation of distal air space liquid clearance in adult guinea-pigs. Cortisol synthesis was inhibited with the 11-beta-hydroxylase inhibitor metyrapone (0-7 days pretreatment). After cortisol synthesis inhibition, distal air space liquid clearance was measured by the increase in concentration of an instilled 5 % albumin solution after 1 h. 2. Two days of metyrapone pretreatment resulted in a 46+/-19 % decrease in plasma cortisol levels compared with control, which was paralleled by a 60+/-13 % decrease in distal air space liquid clearance. The Na+ channel inhibitor amiloride inhibited 40+/-22 % of distal air space liquid clearance in control animals but did not inhibit distal air space liquid clearance in the metyrapone-pretreated group. Co-injection of dexamethasone prevented the inhibition by metyrapone and the amiloride sensitivity of distal air space liquid clearance was greater than in control animals. After 7 days of metyrapone pretreatment, plasma cortisol levels and distal air space liquid clearance were not significantly different from normal, but amiloride sensitivity was greater than in control animals (91+/-37%). 3. Pretreatment with emetine, a protein synthesis inhibitor, reduced distal air space liquid clearance in control animals and in dexamethasone-co-injected animals, but failed to inhibit distal air space liquid clearance after metyrapone pretreatment. Expression of the epithelial sodium channel alpha-subunit (alphaENaC) mRNA in lung tissue was decreased after 2 days of metyrapone pretreatment and after 7 days pretreatment or after co-injection with dexamethasone, alphaENaC mRNA expression was restored towards control levels. 4. Thus, endogenous cortisol is important for maintaining normal liquid balance in the adult guinea-pig lung and a critical regulatory pathway is by modulation of ENaC expression and/or function.

Amiloride↗

Factors associated with life space among community-living rural elders in Japan.

OBJECTIVE: The study objective was to identify factors associated with life space to examine the service needs of the elderly. Cross-sectional study. SAMPLE: 2,409 community-living elderly in a rural town in Japan. MEASUREMENTS: Daily activity level was used as a proxy for life space. Respondents were asked about their daily activity, health status, and psychosocial factors in a self-administered questionnaire. Factors associated with life space were identified using general linear models. Relative associations of each factor with life space were tested using stepwise multiple regression procedure. RESULTS: Elderly in a smaller life space were significantly older, had more illnesses, worse activities of daily living (ADL), and poor self-rated health. Poor psychological well-being and fewer social relations were also associated with a smaller life space. Age and ADL difficulty accounted for 51.7% of life space variations. In addition, more elderly with ADL difficulty expressed unmet needs for transportation and socializing opportunities. CONCLUSIONS: Life space was related not only to age or health status but also to environmental or psychosocial factors. Appropriate services for a vulnerable population may have a positive effect on elderly health. Moreover, elderly life space may be used as an indicator to identify people at risk in order to provide more effective community-based programs for the elderly.

Activities of Daily Living↗

Comparison study of the kinetics of ceftizoxime penetration into extravascular spaces with known surface area/volume ratio in vitro and in vivo in rabbits.

The extravascular kinetics of ceftizoxime were studied both in an in vitro kinetic model and in an in vivo rabbit model. Visking tubing chambers were used in both models to provide extravascular spaces with large or small volumes and surface areas, but identical surface area/volume ratios. Four rabbits, each implanted with two large Visking chambers and four small chambers, received 50 mg of ceftizoxime per kg intramuscularly every 3 h for eight doses. In the in vitro model, 80 mg of ceftizoxime was infused over 30 min every 3 h for eight doses. Intravascular and extravascular spaces were sampled in both models after the eighth dose. Ceftizoxime had similar intravascular kinetics in both models, i.e., the peak levels, the peak-to-trough fluctuations, and the half-life were comparable. The area under the curve (AUC) for the extravascular spaces was also similar in the two models. Large and small chambers having identical surface area/volume ratios demonstrated identical kinetics. The extravascular Visking chamber spaces achieved equilibrium with the intravascular spaces in both models, i.e., the AUC for the extravascular spaces was the same (P > 0.2) as that for the serum (rabbit model) or the test chamber (in vitro model). This study illustrates (i) that our modified in vitro model is a potentially valid model for studying extravascular kinetics; (ii) that extravascular spaces with identical surface area/volume ratios show similar penetration kinetics with a freely diffusible drug, such as ceftizoxime, despite differences in size; and (iii) that the Visking chamber extravascular-space model permits the free diffusion of the antimicrobial agent and reaches equilibrium (equivalent AUC) with the intravascular space.

Animals↗

Green space, urbanity, and health: how strong is the relation?

STUDY OBJECTIVES: To investigate the strength of the relation between the amount of green space in people's living environment and their perceived general health. This relation is analysed for different age and socioeconomic groups. Furthermore, it is analysed separately for urban and more rural areas, because the strength of the relation was expected to vary with urbanity. DESIGN: The study includes 250 782 people registered with 104 general practices who filled in a self administered form on sociodemographic background and perceived general health. The percentage of green space (urban green space, agricultural space, natural green space) within a one kilometre and three kilometre radius around the postal code coordinates was calculated for each household. METHODS: Multilevel logistic regression analyses were performed at three levels-that is, individual level, family level, and practice level-controlled for sociodemographic characteristics. MAIN RESULTS: The percentage of green space inside a one kilometre and a three kilometre radius had a significant relation to perceived general health. The relation was generally present at all degrees of urbanity. The overall relation is somewhat stronger for lower socioeconomic groups. Elderly, youth, and secondary educated people in large cities seem to benefit more from presence of green areas in their living environment than other groups in large cities. CONCLUSIONS: This research shows that the percentage of green space in people's living environment has a positive association with the perceived general health of residents. Green space seems to be more than just a luxury and consequently the development of green space should be allocated a more central position in spatial planning policy.

Adolescent↗

The possibility of changing meaning in light of space and place.

The author considers the possibility of changing meaning in light of space and place. Many questions are raised, including a fundamental question: If we simply choose the meaning of space and place based on personal knowing, regardless of the space and place we are in, does space and place really matter with regard to the possibility of changing meaning? Many possibilities of changing meaning in light of space and place are explored, including the influence of personal knowing, new life experiences and understandings, changes to space and place, unique languaging in space and place, imaging space and place, and engaging in the wonder and mystery of space and place beyond this realm. The possibility of changing meaning is significant in that new meanings open doors to different choices-and living choices is living health.

Choice Behavior↗

The effect of orthotic devices on freeway space.

After any orthotic device placement, there are three possible outcomes to the freeway space. The freeway space is either decreased, unchanged, or increased. The objective of this study was to determine what effect the placement of an orthotic device has on freeway space. Freeway space was measured in a group of 26 subjects immediately after placement of an orthotic device. In a second group of 26 subjects, freeway space was measured at least one week after placement of their orthotic devices. The freeway space was measured along the closing trajectory path during function. The number recorded was based on the actual measurement of the freeway space using a computer measuring device. Both sets of data were analyzed without taking into account other factors which may have influenced the freeway space. A Mann Whitney U test showed no significant differences between the two groups (Z = 0.027, P = 0.978 ). This study concluded that the thickness of an orthotic device does not necessarily increase or decrease freeway space.

Follow-Up Studies↗