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PubMed1995

Adenosine, methacholine, and exercise challenges in children with asthma or paediatric chronic obstructive pulmonary disease.

BACKGROUND: Bronchial hyperreactivity to methacholine is present in children with asthma and other types of paediatric chronic obstructive pulmonary disease (COPD), while hyperreactivity to exercise is more specific for asthma. Adenosine 5'-monophosphate (AMP) is a potent bronchoconstrictor and, like exercise, may provoke asthma by activating mast cells. This study investigated the suitability of AMP as a specific challenge for asthma in children. METHODS: Bronchial provocation challenges with methacholine and AMP were performed in a double blind fashion using tidal breathing in 51 children with asthma, 21 with paediatric COPD of various types, and in 19 control children. Each subject also underwent a standardised exercise challenge after inhalation challenges were completed. Sensitivity and specificity curves were constructed and the intersection point of sensitivity and specificity for each type of challenge was determined. RESULTS: When the asthmatic patients were compared with the children with COPD, the intersection points for AMP, exercise and methacholine were 90%, 85%, and 50%, respectively. When compared with the controls the same intersection points were 98%, 84%, and 92%, and when children with paediatric COPD were compared with controls they were 55%, 50%, and 82%. CONCLUSIONS: Methacholine distinguishes both asthma and paediatric COPD from controls with a sensitivity of 82-92%, but does not distinguish between asthma and paediatric COPD; exercise and AMP distinguish asthma from controls with a sensitivity and specificity of 84-98% but they also distinguish asthma from paediatric COPD with a sensitivity and specificity of 85-90%. AMP inhalation is a practical aid for diagnosing asthma and distinguishing it from COPD in children of all ages.

Adenosine Monophosphate↗

PubMed1999

New analytic framework for understanding sympathetic baroreflex control of arterial pressure.

The sympathetic baroreflex is an important feedback system in stabilization of arterial pressure. This system can be decomposed into the controlling element (mechanoneural arc) and the controlled element (neuromechanical arc). We hypothesized that the intersection of the two operational curves representing their respective functions on an equilibrium diagram should define the operating point of the arterial baroreflex. Both carotid sinuses were isolated in 16 halothane-anesthetized rats. The vagi and aortic depressor nerves were cut bilaterally. Carotid sinus pressure (CSP) was sequentially altered in 10-mmHg increments from 80 to 160 mmHg while sympathetic efferent nerve activity (SNA) and systemic arterial pressure (SAP) were recorded simultaneously under various hemorrhagic conditions. The mechanoneural arc was characterized by the response of SNA to CSP and the neuromechanical arc by the response of SAP to SNA. We parametrically analyzed the relationship between input and output for each arc using a four-parameter logistic equation model. In baseline states, the two arcs intersected each other at the point at which the instantaneous gain of each arc attained its maximum. Severe hemorrhage lowered the gain and offset of the neuromechanical arc and moved the operating point, whereas the mechanoneural arc remained unchanged. The operating points measured under the closed-loop conditions were indistinguishable from those estimated from the intersections of the two arc curves on the equilibrium diagram. The average root mean square errors of estimate for arterial pressure and SNA were 2 and 3%, respectively. Such an analytic approach could explain a mechanism for the determination of the operating point of the sympathetic baroreflex system and thus helps us integratively understand its function.

Animals↗

PubMed1994

Parasympathetic-mediated reflex salivation and vasodilatation in the cat submandibular gland.

The aim of the present study was to compare and characterize the secretory and vasodilator effects induced by chorda lingual nerve (CLN) stimulation (i.e., direct parasympathetic stimulation) and reflex parasympathetic stimulation in the submandibular gland (SMG) of sympathectomized cats. The increase in blood flow and salivary secretion in response to electrical stimulation of the central cut ends of the vagus and inferior alveolar nerves, as well as to stimulation of the CLN at a site approximately 5 mm distal to the intersection of the CLN and the SMG duct (site D) was completely abolished by section of the chorda tympani nerve (CTN). Neither response to CLN stimulation at a site nearly 5 mm proximal to the intersection of the CLN and the SMG duct (site C) was affected by CTN section. Section of the CLN at a site approximately 5 mm distal to the intersection of the CTN and the CLN abolished the submandibular salivary and vasodilator responses elicited by CLN stimulation at site D but had no effect on the two responses evoked by CLN stimulation at site C. The blood flow increases evoked by electrical stimulation of the CLN at site D were greatly reduced by prior treatment with the autonomic ganglion blocker hexamethonium, but the vasodilator responses evoked from site C were reduced much less. These data suggest that the secretory and vasodilator responses elicited by CLN stimulation at site D and those by vagus and inferior alveolar nerve stimulation are mediated largely via a parasympathetic reflex mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1981

Deficiencies in pore-membrane models of microvascular fluid and solute transudation.

We have attempted to determine the membrane parameters, permeability-surface area product (PS) and reflection coefficient (sigma), necessary to describe solute exchange in the pulmonary circulation. Experimental lymph-to-plasma ratios were obtained for total protein (Rtot) and albumin (Ralb) using lung lymph collected from goats with chronic lung lymph fistulae. Lymph flow (QL) and solute flow (QS) were varied by increasing microvascular pressure in a stepwise manner by inflating a balloon in the left atrium. The increased QL and decreased Ralb from multiple experiments in four goats were used to plot PS vs. sigma using the equation of Patlak et al. (J. Theor. Biol. 5: 426-442, 1963). The region of intersection of two or more such curves should identify the two membrane constants. However, these curves rarely intersected suggesting that perhaps the lung barrier was not adequately represented by a single homoporous membrane. To evaluate heteroporosity, the three-pore model of Blake and Staub (Microvasc. Res. 12: 197-220, 1976) was investigated. By use of their pore sizes and relative pore distributions, values for the fluid filtration coefficient, PS, and sigma of each pore type were calculated, and finally QL and R were predicted at various microvascular pressures. When these calculated values of QL and R were plotted using the equation of Patlak et al., an equivalent homoporous PS and sigma could still be found. Therefore, a heteroporous membrane does not appear to explain the failure of our data plots to intersect. Possible alternative models are suggested.

Animals↗

PubMed2006

Reversibility of exercise-induced dendritic attenuation in brain cardiorespiratory and locomotor areas following exercise detraining.

It has been shown previously that dendritic branching in cardiorespiratory and locomotor brain areas can be attenuated with exercise training (ET). It was not known whether this process was reversible. Twenty-three (n = 23) male Sprague-Dawley rats were individually caged and divided into two groups: untrained (UN; n = 11) and detrained (DTR; n = 12). DTR were provided with a running wheel at 21 days of age and exercised spontaneously. After 120 days (70 days of ET followed by 50 days of detraining), ET indexes were obtained, including maximal oxygen uptake, percent body fat, resting heart rate, and heart weight-to-body weight ratios. The brain was processed according to a modified Golgi-Cox procedure. Impregnated neurons from the periaqueductal gray (PAG), posterior hypothalamic area (PH), nucleus of the tractus solitarius (NTS), and cuneiform nucleus (CfN) were examined in coronal sections. Neurons were traced using a camera lucida technique and analyzed using the Sholl concentric ring analysis of dendritic branching. t-Tests compared the mean number of intersections per neuron by grouping inner rings, outer rings, and total number of intersections per animal. There were no significant differences between UN and DTR in PH, PAG, CfN, and NTS in the inner rings, outer rings, and total number of intersections per animal. A separate group of animals was used to show that a training effect in the CfN and NTS was present at 56 days of ET. Our results show that dendritic attenuation resulting from 70 days of ET in PH, PAG, CfN, and NTS is completely reversed with 50 days of detraining.

Adaptation, Physiological↗

PubMed2005

Neuroplastic adaptations to exercise: neuronal remodeling in cardiorespiratory and locomotor areas.

Neuronal activity has been shown to be attenuated in cardiorespiratory and locomotor centers of the brain in response to a single bout of exercise in trained (TR) vs. untrained (UN) animals, but the mechanisms remain obscure. Based on this finding, dendritic branching patterns of seven brain areas associated with cardiorespiratory and locomotor activity were examined in TR and UN animals. Twenty-eight male Sprague-Dawley rats were kept in individual cages and divided into TR and UN. TR were provided with a running wheel and exercised spontaneously. After 85 or 120 days, exercise training indexes were obtained, including maximal oxygen consumption, percent body fat, resting heart rate, and heart weight-to-body weight ratios. The brain was removed and processed according to a modified Golgi-Cox procedure. Impregnated neurons from seven brain areas were examined in coronal sections: the periaqueductal gray, posterior hypothalamic area, nucleus of the tractus solitarius, rostral ventrolateral medulla, cuneiform nucleus, nucleus cuneatus, and cerebral cortex. Neurons were traced using a camera lucida technique and analyzed using the Sholl analysis of dendritic branching. t-tests were conducted to compare the mean number of intersections per neuron by grouping inner rings and outer rings and also comparing the total number of intersections per animal. There were significant differences between groups in the posterior hypothalamic area, periaqueductal gray, cuneiform nucleus, and nucleus of the tractus solitarius in the inner rings, outer rings, and the total number of intersections per animal. Our results show that dendritic fields of neurons in important cardiorespiratory and locomotor centers of the brain are attenuated in TR animals.

Adaptation, Physiological↗

PubMed1996

Neurons in the supplementary eye field of rhesus monkeys code visual targets and saccadic eye movements in an oculocentric coordinate system.

1. We investigated whether neurons in the supplementary eye field (SEF) of macaque monkeys code saccadic eye movements in oculocentric coordinates (relative to the current direction of fixation) or in craniocentric coordinates (relative to the head). Craniocentric coding in SEF had been previously suggested by the convergent appearance of electrically elicited saccades originating at different orbital positions. 2. We primarily studied SEF neurons that started responding before the beginning of saccades because such presaccadic activity is likely related to saccade generation and metrics. Using a memory-saccade task, we classified the presaccadic activity of each neuron as either purely visual related, purely movement related, or both visual and movement related. 3. We then mapped the response fields (receptive fields and movement fields) of SEF neurons from different orbital positions. When mapped relative to a central fixation point, the strongest responses for a given SEF neuron invariably occurred for a particular polar direction with fairly symmetrical declines for departures from that direction. When tested using other fixation point locations, their strongest responses almost always continued to occur for stimuli having the same polar direction relative to each fixation point tested, and thus they appeared to code both stimulus direction and saccade direction in an oculocentric coordinate system. 4. The effect of eye position on SEF presaccadic activity was quantified in two ways by computing, for each neuron, 1) an "intersection distance," the eccentricity of the point where extensions of the neuron's optimal polar directions measured at two eccentric orbital positions converged, and 2) an "orbital perturbation index" such that an index of 0 corresponded to no change in the neuron's optimal polar direction across different orbital positions (i.e., perfectly oculocentric response fields) and an index of 1 corresponded to optimal polar directions that converged to the same craniocentric goal regardless of initial eye position (i.e., perfectly craniocentric response fields). For neurons with both visual and movement responses, these measures were calculated separately for each type of activity using tasks that temporally separated the visual cue presentation and the saccade to it. 5. Almost all of the intersection distances were well beyond the oculomotor range (+/- 50 degrees) of the monkey (38/39 for movement activity and 62/66 for visual activity). The median intersection distance for visual activity was very large (274 degrees), and the median for movement activity was slightly divergent (beyond infinity). Thus SEF neurons rarely showed a conspicuous convergence of response field direction. 6. Likewise, the mean orbital perturbation indexes were very small (-0.04 +/- 0.21, mean +/- SD, for movement activity and 0.09 +/- 0.15 for visual activity), also indicating that SEF neurons code stimuli and saccades in an oculocentric manner. 7. For neurons with both visual and movement activities, the orbital perturbation indexes of the two activities were not significantly correlated (r = 0.16), even though their characteristic directions (optimal polar direction estimated from the center of the screen) were almost the same (circular correlation, r+ = 0.97). The lack of a significant correlation between the visual and movement activity orbital perturbation indexes is consistent with the hypothesis that most of the variation in this index represents statistically independent errors of measurement. Conversely, the strong covariation of visual and movement activity characteristic directions indicates that directional preference is a fundamental functional property of SEF presaccadic activity.(ABSTRACT TRUNCATED)

Animals↗

PubMed2005

Ultraviolet photography of the in vivo human cornea unmasks the Hudson-Stähli line and physiologic vortex patterns.

PURPOSE: To perform ultraviolet (UV) macrophotography of the normal in vivo human cornea, establishing biometric data of the major component of UV absorption for comparison with the Hudson-Stähli (HS) line, the distribution of iron demonstrated by Perl stain, and cases of typical amiodarone keratopathy. METHODS: Nonrandomized comparative case series of UV photographs of 76 normal corneas (group 1) and 16 corneas with typical amiodarone keratopathy (group 2). Image-analysis software was used to grade the major component of UV absorption for slope and the coordinates of its points of intersection with the vertical corneal meridian and inflection. RESULTS: In group 1 the major component had a mean slope of 5.8 degrees, sloping down from nasal to temporal cornea. The mean coordinates of points of intersection with the vertical corneal meridian and inflection were (0, 0.30) and (0.02, 0.31), respectively. No significant differences between groups 1 and 2 were found for slope (P = 0.155), intersection with the vertical corneal meridian (P = 0.517), and point of inflection (P = 0.344). The major component of UV absorption was consistent with published characteristics of the HS line, and coincidence of UV absorption and Perl-stained iron was demonstrated in one corneal button. A vortex pattern of UV absorption was observed in all corneas. CONCLUSIONS: UV photography demonstrates subclinical corneal iron, confirming its deposition in an integrated HS line/vortex pattern. Coincident iron and amiodarone deposition occurs in amiodarone keratopathy.

Adult↗

PubMed1989

Modeling of Doppler signal considering sample volume and field distribution.

The ultrasound Doppler amplitude spectrum for a single scatterer and the power spectrum for multiple scatterers were calculated in terms of the echo signal from scatterers crossing the sample volume, defined by the transmitted pulse and the diffracted field distribution for cw. The observation time for the Doppler signal is also considered. Statistical parameters such as mean and variance of the Doppler power spectrum are studied as continuous functions of the intersection angle between the beam axis and the flow direction, the pulse length and the viewing position. The derived equations are valid whether the transit time is governed by the pulse length, or beam geometry, or both. It is shown that the Doppler power spectra calculated by the proposed model and by the Doppler signal obtained from field theory are in good agreement. It is also shown that, when the Doppler signal broadening due to the transmitted pulse and beam geometry is constant without regard to the intersection angle, the degree of spread of the velocity distribution can be estimated from the variance of the Doppler power spectrum measured by the Doppler system once the intersection angle is known.

Blood Flow Velocity↗

PubMedDate not supplied

Effect of electrical stimulation on arteriogenesis and angiogenesis after bilateral femoral artery excision in the rabbit hind-limb ischemia model.

The effects of electrical stimulation (ES) on arteriogenesis (the opening of preexisting collaterals) and angiogenesis (formation of new capillaries) were studied after acute bilateral hind limb ischemia was induced via bilateral femoral artery excision in a rabbit model. The study evaluated the rabbit hind limbs' normal response to acute ischemia and to application of ES by calculating changes in arterial and capillary densities. Comparisons were made with our prior study, in which the femoral artery was unilaterally excised, as we attempted to expand on the topics of arteriogenesis and angiogenesis. Twelve adult New Zealand white rabbits were randomly assigned to 1 of 2 series. In Series 1, the control group, both femoral arteries were excised and no ES was applied. In Series 2, both femoral arteries were excised and ES was applied to the left limb. One lead was implanted into the left adductor muscle near the site of the excised left femoral artery (Series 2), and a stimulator (Thera, Medtronic, Inc, Minneapolis, MN) was implanted in a separate pocket. ES was applied at a rate of 3 V, 30 contractions per minute, beginning immediately after surgery and continuously for 1 month. Angiography was performed in all 12 rabbits 1 month after surgery to establish the anatomy of the collateral vessels and to demonstrate that the femoral artery stump continued to be an end artery. Contrast-opacified arteries (COAs) that crossed the grid's midline, and the total number of grid lines intersected by COAs, were tallied according to an established method. Capillary density was calculated as the number of capillaries per square millimeter of muscle. In Series 1, after 1 month, the number of COAs crossing the grid's midline was 4.5 +/-1.5 on the left and 4.8 +/-1.2 on the right side. In Series 2, the number of COAs crossing the grid's midline was 7.9 +/-1.8 on the left side (p<0.05 vs Series 1) and 5.9 +/-1.6 on the right side of the same rabbit (p=NS vs Series 1). In Series 1, 36.7 +/-5.4 and 30.5 +/-7.7 total intersections were crossed by COAs on the left and right sides, respectively. In Series 2, total grid intersections crossed by COAs were 48.4 +/-8.5 and 47.5 +/-9.1 in the left and right sides, respectively (p<0.001 vs series 1). Baseline capillary density before femoral artery excision was 180.2 +/-21.3/mm(2). The capillary densities on the left sides were 94.2 +/-19.1 and 264.5 +/-7.6 in Series 1 and 2, respectively (p<0.001). The right sides showed a similar pattern with capillary densities of 88.5 +/-37.2 and 135.8 +/-6.8 (p<0.05) in Series 1 and 2, respectively. When capillary density was compared on the left and right sides of the same rabbit in Series 2, a statistically significant increase was also found; 264.5 +/-7.6 vs 135.8 +/-6.8 (p<0.001) in the left and right sides, respectively. Comparisons of the effect of electrical stimulation and the body's normal physiologic response to acute ischemia revealed a significant increase in the opening of preexisting collaterals (arteriogenesis) and the promotion of capillary density (angiogenesis) with the use of electrical stimulation.

Angiography↗

PubMed2006

Surgical anatomy of microneurosurgical sulcal key points.

OBJECTIVE: The brain sulci constitute the main microanatomic delimiting landmarks and surgical corridors of modern microneurosurgery. Because of the frequent difficulty in intraoperatively localizing and visually identifying the brain sulci with assurance, the main purpose of this study was to establish cortical/sulcal key points of primary microneurosurgical importance to provide a sulcal anatomic framework for the placement of craniotomies and to facilitate the main sulci intraoperative identification. METHODS: The study was performed through the evaluation of 32 formalin-fixed cerebral hemispheres of 16 adult cadavers, which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes necessary for the evaluation of cranial-cerebral relationships. Three-dimensional anatomic and surgical images are displayed to illustrate the use of sulcal key points. RESULTS: The points studied were the anterior sylvian point, the inferior rolandic point, the intersection of the inferior frontal sulcus with the precentral sulcus, the intersection of the superior frontal sulcus with the precentral sulcus, the superior rolandic point, the intersection of the intraparietal sulcus with the postcentral sulcus, the superior point of the parieto-occipital sulcus, the euryon (the craniometric point that corresponds to the center of the parietal tuberosity), the posterior point of the superior temporal sulcus, and the opisthocranion, which corresponds to the most prominent point of the occipital bossa. These points presented regular neural and cranial-cerebral relationships and can be considered consistent microsurgical cortical key points. CONCLUSION: These sulcal and gyral key points can be particularly useful for initial intraoperative sulci identification and dissection. Together, they compose a framework that can help in the understanding of hemispheric lesion localization, in the placement of supratentorial craniotomies, as landmarks for the transsulcal approaches to periventricular and intraventricular lesions, and in orienting the anatomic removal of gyral sectors that contain infiltrative tumors.

Adult↗

PubMed2002

Orthogonal planar laser polarization spectroscopy.

Planar laser polarization spectroscopy has recently been used to image the hydroxyl radical in combustion for small intersection angles of pump and probe beams. We report an experimental configuration that allows planar laser polarization imaging for perpendicular intersection of pump and probe beams. We demonstrate what to our knowledge is the first planar laser polarization spectroscopy imaging at a 90 degree intersection of pump and probe beams for both linearly and circularly polarized pump beams.

Journal Article↗

PubMed2001

Increments and decrements in color constancy.

The present study examines whether increment-decrement asymmetries reported in a number of recent center-surround situations occur in more complex images as well. Subjects saw the CRT simulation of a whole uniformly illuminated array of foreground surfaces presented against a large background surface and, for a number of different viewing contexts, made achromatic settings over a wide range of luminance values. Three results emerged. First, subjects' achromatic loci did not fall on a single straight line in color space but rather fell on two separate lines intersecting at some point in this space. Second, the intersection points were not identical to but dependent largely on background color and showed only small effects of foreground colors. Third, cone signals that were decremental relative to the intersection point were more responsive to illuminant changes than cone signals that were incremental, the latter additionally showing some variation with foreground colors. The results are interpreted in terms of increment-decrement asymmetries. They suggest that these asymmetries occur in more complex images as well.

Color Perception↗

PubMed2002

Neural grouping and geometric effect in the determination of apparent orientation.

We propose that neural grouping of retinotopically distributed responses in the primary visual cortex (V1) is essential for the determination of apparent tilt, including the tilt illusion. Our psychophysical study shows that apparent tilt is independent of stereo disparity, hue, or contrast of bars, which determine the ownership of their intersection. This leads us to suspect that the neuronal responses within the intersection are excluded from the computation of apparent tilt. To investigate the underlying cortical mechanisms, we developed and examined a V1 network model including the collinear connections observed in the superficial layers. The model shows good agreement with the results of psychophysical experiments, including segmentation independence, contrast dependence, and apparent tilt for various stimuli. The results suggest that collinear connections underlie the neural grouping that excludes the intersection region and establishes the independence of segmentation.

Journal Article↗

PubMed2005

Blind and sighted pedestrians' judgments of gaps in traffic at roundabouts.

This paper reports two experiments about street crossing under conditions of free flowing traffic, with a focus on modem roundabout intersections. Experiment 1 was conducted at three roundabouts varying in size and traffic volume. Six totally blind and six sighted adults judged whether gaps in traffic were long enough to permit crossing to the median (splitter) island before the next vehicle arrived. Gap distributions and measures of judgment quality are reported. Overall, blind participants were about 2.5 times less likely to make correct judgments than sighted participants, took longer to detect crossable gaps, and were more likely to miss crossable gaps altogether. However, the differences were significant only at the two higher volume roundabouts. In Experiment 2, we evaluated the response of drivers to pedestrians with and without mobility devices (i.e., long canes, dog guides). The experiment was conducted at a single-lane roundabout, a midblock crossing, and a two-way-stop-controlled intersection. Site-specific characteristics appeared to have a greater impact on drivers' yielding than did a mobility device. Actual or potential applications of this research include the development of methods for assessing pedestrian safety and driver behavior as well as identifying intersections that may require modification in order to be accessible to blind pedestrians.

Accidents, Traffic↗

PubMed1988

Alterations in uterine epithelial tight junction structure during the oestrous cycle and implantation in the pig.

The structure of the pig uterine epithelium tight junction has been studied using freeze-fracture methods during oestrus and implantation. Compared with non-pregnant non-cyclic pigs, in both pregnancy and during the cycle the number of intersections per unit area of the tight junction ridges increases to a maximum 16 days after ovulation. There was no significant alteration in the depth or number of ridges in the tight junction band. The only significant difference between tight junctions in cyclic and pregnant pigs was a brief increase in the depth during the cycle (12-15 days after ovulation). The number of intersections is thought to be a far more important measure than depth in determining the permeability of the tight junction. It therefore seems unlikely that changes in tight junction structure play any direct role in the rescue of the corpus luteum or in establishing pregnancy but merely reflect the alterations in progesterone concentrations. However, the decrease in uterine permeability indicated by the increase in intersection frequency has been reported for other species and may reflect an important change in the uterine milieu in preparation for a possible pregnancy, apparently induced by alterations in progesterone concentration.

Animals↗

PubMed2003

Influence of socioeconomic status on the effectiveness of bicycle helmet legislation for children: a prospective observational study.

OBJECTIVE: To evaluate the influence of average family income in a geographic area on the effectiveness of helmet legislation on observed helmet use by children (5-14 years). METHODS: The study was conducted in East York, a health district of Metropolitan Toronto, in collaboration with the East York Health Unit. In 1996, the total population was 107 822, 11 340 of which were children 5 to 14 years. Census data were used to group the 21 census tracts in East York into 7 geographically distinct areas. The boundaries of these areas are natural barriers to travel, such as expressways, ravines, railway tracks, and hydroelectric power lines. The areas were also ranked according to average family income (based on Statistics Canada data). For analytical purposes, areas were defined as low-, mid-, and high-income areas. Census data profiles of the areas have been previously described. For each consecutive year from 1990 to 1997 inclusive, direct observations of children riding bicycles in East York during the months of April through October were made. In 1995, observations were completed before the introduction of the law on October 1, 1995. Only children who were between 5 and 14 years of age and riding a 2-wheeled bicycle were included in the study. In total, 111 sites across all 7 areas were selected for observation. Observational sites included school yards of all elementary and middle schools (kindergarten to grade 8) and all parks in East York. In addition, 5 major intersections and 5 residential streets from each area were randomly selected. Observers were trained and used a standardized data collection form. A pilot study showed that the data collected by observers were reliable and valid. Observers remained at each site for 1 hour and collected data on helmet use and sex. Ethical approval for the study was obtained from the Hospital for Sick Children Research Ethics Board, the East York Board of Education, and the Metropolitan Separate School Board. The proportion of children who were wearing a bicycle helmet was estimated by year (1990-1997, inclusive), sex (male, female), location (school, park, major intersection, residential street), and income area (low, mid, high). For estimating the effect of legislation on helmet use, data from the year immediately after legislation (1996) were compared with data from the year preceding legislation (1995). The relative risk (RR) of helmet use (after vs before legislation) was calculated along with a 95% confidence interval (CI). Logistic regression analysis was used to adjust for potential confounding variables (sex and location). RESULTS: During the 8-year study period, 9768 observations were made (range: 914-1879 observations per year). The proportion of child cyclists who wore a bicycle helmet increased steadily during the first 4 years of the study period, from 4% in 1990 (34 of 914), to 16% in 1991 (303 of 1879), to 25% in 1992 (383 of 1563), and to 45% in 1993 (438 of 984). During 1994 (460 of 1083) and 1995 (568 of 1227), helmet use remained relatively stable at approximately 44%. Helmet use rose markedly in 1996 (the first year after helmet legislation was introduced) to 68% (818 of 1202) and remained stable at 66% (609 of 916) in 1997. Throughout the study period, girls were consistently more likely to wear helmets than were boys. In total, 47% (1420 of 3047) of girls wore helmets, compared with 33% (2193 of 6721) of boys (RR: 1.43; 95% CI: 1.36-1.50). In addition, children who were riding to school were more likely to use helmets, compared with children who were riding on residential streets, major intersections, and parks. Overall, 48% (1497 of 3129) of children who were riding to school wore bicycle helmets, compared with 32% (2116 of 6639) of children who were riding at other locations (RR: 1.50; 95% CI: 1.43-1.58). Children in the high-income areas were consistently more likely to wear helmets, compared with children in the mid- and low-income areas. Helmet legislation was associated with a significant increase in helmet use by children in East York. In 1995, 46% (ast York. In 1995, 46% (568 of 1227) of children wore bicycle helmets, compared with 68% (818 of 1202) of children in 1996 (RR: 1.47; 95% CI: 1.37-1.58). The effect of legislation, however, varied by income area. In low-income areas, helmet use increased by 28% after legislation, from 33% (213 of 646) in 1995 to 61% (442 of 721) in 1996 (RR: 1.86; 95% CI: 1.64-2.11). In mid-income areas, helmet use increased by 29% after legislation, from 50% (150 of 300) in 1995 to 79% (185 of 234) in 1996 (RR: 1.58; 95% CI: 1.39-1.80). In high-income areas, helmet use increased by only 4%, from 73% (205 of 281) in 1995 to 77% (191 of 247) in 1996 (RR: 1.06; 95% CI: 0.96-1.17). This finding of a significant increase in helmet use after legislation in low- and mid-income areas but not in high-income areas remained even after logistic regression analysis adjusted for sex and location. CONCLUSIONS: This study showed that bicycle helmet use by children increased significantly after helmet legislation. In this urban area with socioeconomic diversity and in the context of prelegislation promotion and educational activities, the legislative effect was most powerful among children who resided in low-income areas.

Accidents, Traffic↗

PubMed2006

Three-dimensional glenoid deformity in patients with osteoarthritis: a radiographic analysis.

BACKGROUND: In osteoarthritis of the shoulder, the tilt of the glenoid surface undergoes an eccentric deformation not only in the anteroposterior but also in the superoinferior direction. The goals of this study were to analyze glenoid version in the coronal plane and to clarify the relationship between retroversion and inferior inclination of the glenoid. METHODS: Standardized radiographs of 100 consecutive patients with primary osteoarthritis of the shoulder and 100 otherwise healthy patients with shoulder pain (the control group) were included in this study and were analyzed by two independent observers. RESULTS: We defined four different types of inclination deformity of the glenoid. In a type-0 glenoid, a line at the base of the coracoid process and a line at the glenoid rim run parallel. Both lines intersect below the inferior glenoid rim in a type-1 glenoid. In a type-2 glenoid, the line at the base of the coracoid process and the glenoid line intersect between the inferior glenoid rim and the center of the glenoid. In a type-3 glenoid, the lines intersect above the base of the coracoid process. A significant difference (p < 0.0001) in the distribution of glenoid types between the two patient groups was observed. Forty-seven patients with osteoarthritis showed combined posterior and inferior glenoid wear. We found no correlation between the type of inclination and the type of glenoid morphology. The interobserver reliability of our observations was very high. CONCLUSIONS: In osteoarthritis, eccentric inferior glenoid wear is frequent and independent from retroversion deformity of the glenoid. Normalization of glenoid version in both transverse and coronal planes may reduce eccentric loading of the prosthetic glenoid, which has been associated with loosening.

Adult↗