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PubMed2000

Adapting the waterproof BMS-96 diode array for isodose determination of dynamic beams.

We report the application of the Schuster BMS-96 waterproof linear diode array for isodose determination of dynamic beams. The array recorded beam profiles correctly, while depth dose distributions of dynamic beams with large variations in dose rate were registered erroneously. The deviations could be eliminated by appropriate software modifications. Until the software is revised, true isodoses can be obtained by rescaling each individual profile to the depth dose curve as measured with a single ionization chamber. After the corrections presented in the paper, isodoses interpolated from these corrected data sets agreed with ionization chamber measurements within 1-2%.

Radiation Dosage↗

PubMed2004

In vitro marginal adaptation of high-viscosity resin composite restorations bonded to dentin cavities.

PURPOSE: The aim of this study was to evaluate the marginal adaptation of high-viscosity resin composite restoratives bonded to dentin in a cylindrical cavity model. MATERIALS AND METHODS: The buccal enamel of 64 human premolars was removed and cylindrical cavities 3 mm in diameter and 1.3 mm in depth were prepared on each dentin surface. The cavities were divided into 8 groups of 8 cavities each and restored according to the manufacturers' instructions with the following adhesive/composite systems: Bond 1/Alert, Stae/Glacier, OptiBond Solo/Prodigy Condensable, One-Step/Pyramid, Solidbond/Solitaire, Prime&Bond NT/Surefil, One Coat Bond/Synergy, and Scotchbond 1/Z250. The composite surfaces were pressed against mylar strips, covered with cover slips, and photopolymerized in a single increment for 40 s. The restorations were polished with wet SiC papers of 320 to 1000 grit size to expose dentin margins. The marginal adaptation was evaluated immediately after photopolymerization and again after 1 week of storage in water at 37 +/- 1 degrees C. Evaluation was performed under a metallographic microscope at 200X magnification by recording the frequency of gap-free restorations (GF), the percentage length of the debonded margins relative to the cavity periphery (DM), the width of the maximum marginal gap (MG), and the marginal index (MI = MG x DM / 100). The results were statistically analyzed with one-way ANOVA and the Mann-Whitney U-test at alpha = 0.05. RESULTS: No incidence of gaps was found in 62.5% of One Coat Bond/Synergy and 37.5% of OptiBond Solo/Prodigy Condensable restorations. All the other restorative systems exhibited restorations with gaps. One Coat Bond/Synergy, Scotchbond 1/Z250, and OptiBond Solo/Prodigy Condensable were the groups with the lowest DM values, while Stae/Glacier showed the highest DM values. One Coat Bond/Synergy and OptiBond Solo/Prodigy Condensable revealed the lowest MI values and Stae/Glacier the highest. No statistically significant differences were recorded between immediate evaluation and evaluation after 1 week of water storage. CONCLUSION: The results showed that all the adhesive/composite systems examined failed to achieve gap-free margins with dentin. The restorative systems One Coat Bond/Synergy, Optibond Solo/Prodigy Condensable, and Scotchbond 1/Z250 presented the best marginal adaptation of all the systems tested. No improvement was recorded on the quality of marginal adaptation following 1 week of water storage.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2006

Clinical evaluation of two packable posterior composites: 2-year follow-up.

The clinical performance of two packable posterior composites, Alert (A)-Jeneric/Pentron and SureFil (S)-Dentsply, was evaluated in 33 patients. Each patient received one A and one S restoration, resulting in a total of 66 restorations. The restorations were placed by one operator according to the manufacturer's specifications and were finished and polished after 1 week. Photographs were taken at baseline and after 2 years. Two independent evaluators conducted the clinical evaluation by using modified United States Public Health Service criteria. After 2 years, 60 restorations (30 A and 30 S), 27 class I (16 A and 11 S) and 33 class II (14 A and 19 S) were evaluated in 30 patients. Criterion A for recurrent caries, vitality, and retention was applicable to all 60 restorations. Criterion B was distributed among 40 restorations as follows: surface texture (15 A; 2 S), color (5 A; 6 S), postoperative sensitivity (1 S), marginal discoloration (8 A), marginal adaptation (3 A), and wear resistance (2 A). Data were analyzed using the Exact Fisher and McNemar tests. After 2 years, S showed a significantly better performance than A with respect to surface texture and marginal discoloration. The clinical performance of both materials was considered acceptable over the 2-year period. Further evaluations are necessary for a more in-depth analysis.

Adolescent↗

PubMed1999

The use of 2 bioabsorbable barrier membranes in the treatment of interproximal intrabony periodontal defects.

BACKGROUND: The use of barrier membranes in the treatment of periodontal defects is well documented. There has been an increase in the use of bioabsorbable materials which do not require a second surgical procedure for removal. However, there are little data evaluating the efficacy of bioabsorbable membranes in the treatment of intrabony defects. The purpose of this investigation was to evaluate the regenerative potential of 2 bioabsorbable barrier membranes without the use of grafting materials in the treatment of interdental intrabony defects. METHODS: Twenty-three 2- or 3-walled intrabony defects were treated in 19 patients with a mean age of 50.4 years. All had completed nonsurgical treatment and a period of supportive periodontal therapy. The sites were randomly chosen to receive a barrier membrane composed of type I bovine collagen (11) or a copolymer of polylactic acid (PGA/PLA;12). A pressure sensitive disc probe was used to evaluate the following criteria at baseline and re-entry: 1) occlusal surface to the apical depth of probe penetration (OS-DP); 2) occlusal surface to the gingival margin (OS-GM); 3) occlusal surface to the alveolar crest (OS-AC); and 4) occlusal surface to the base of the osseous defect (OS-BD). Full thickness mucoperiosteal flaps were reflected to expose the surgical sites. The defects were debrided of the granulomatous tissue, the root surfaces instrumented and conditioned with 4 one-minute applications of 50 mg/ml of tetracycline. The barrier membranes were adapted to cover the defects and the flaps replaced. The postsurgical healing was uneventful and similar in both treatment modalities. RESULTS: Twenty-three sites were surgically re-entered 6 months from the time of the initial surgery. The deepest probe depth for each site was used for statistical analysis. There was a mean relative attachment gain of 2.58+/-1.90 mm for the collagen, and 2.77+/-2.13 mm for the copolymer. There was a decrease in probing depth of 3.27+/-1.91 mm and 0.69+/-1.35 mm of recession for the collagen. The PGA/PLA copolymer had 3.55+/-2.47 mm reduction in probe depth and 0.78+/-1.14 mm of recession. CONCLUSIONS: The data indicated the bioabsorbable collagen and copolymer membranes resulted in comparable results. A larger sample size would be necessary to determine if one membrane was superior to the other.

Absorbable Implants↗

PubMed1976

The mechanism for small-bowel adaptation in lactating rats.

1. To study the relative contributions of luminal nutrition, bile and pancreatic secretions and hormonal factors in intestinal adaptation, lactation hyperphagia was chosen as a model for increased luminal nutrition, either alone (intestinal transection control group) or in combination with (i) exclusion of bile and pancreatic secretions from the jejunum (by transposition of the jejunum above the Ampulla of Vater) or (ii) exclusion of bile, pancreatic secretions and exogenous luminal nutrition from the jejunum (proximal Thiry-Vella by-pass group). 2. The results confirm that in lactation there is mucosal hyperplasia with increases in villus height and crypt depth, and in small-bowel wet and defatted dry-tissue weights per unit length of intestine. 3. There are corresponding changes in absorptive function with increased glucose and water absorption per unit length of intestine. 4. These structural and functional adaptive changes are proportionately greater in ileum than in jejunum. 5. The exclusion of exogenous luminal nutrition, bile and pancreatic secretions from the jejunum did not diminish the degree of intestinal mucosal hyperplasia and functional adaptation seen in lactation. 6. Diversion to the ileum of greater than normal amounts of bile, pancreatic secretions and luminal nutrition did not further increase the degree of mucosal hyperplasia and enhanced absorption seen in the lactating intestinal transection control group. 7. Unlike other models of intestinal adaptation, the changes in small-bowel mucosal structure and function seen in lactation are probably due to hormonal factors.

Adaptation, Physiological↗

PubMedDate not supplied

[Metabolism of xenobiotics in the liver in acute hypoxia of intact mice and mice adapted to oxygen deficiency].

Experiments on white mice were made to study the effect of acute hypoxia in intact and hypoxia adapted animals on the function of liver hydroxylases. It was shown that acute hypoxia (vacuum 462 Pa, exposure 120 min) leads to a decrease in the rate of amidopyrine demethylation by liver microsomal enzymes. Preadaptation to hypoxia reduces the depth of microsomal hydroxylation inhibition in response to hypoxia. Variation in the constant of substrate binding with the enzymatic complex plays in important role in the mechanism of microsomal oxidation inhibition in the liver under hypoxia. The concentration of the hemoproteins P = 450 and b5 does not undergo any substantial changes.

Acute Disease↗

PubMed2003

Psychological adaptation and distress among HIV+ Latina women: adaptation to HIV in a Mexican American cultural context.

In order to examine the relative importance of general individual orientations (mastery and self-esteem) and specific coping styles with regard to psychological distress among women with HIV, data are examined from a pilot study involving in-depth face-to-face interviews with 32 HIV+ Latinas receiving care at 4 clinics serving the South Texas population. Interviews were conducted to provide preliminary psychometric information on coping and distress instruments in this predominantly Mexican American population as well as to examine psychosocial factors related to individual adjustment to HIV among Latina females. Refusal rates were low in this study (approximately 10%) and measurement instruments generally had acceptable internal consistency reliability. Results of exploratory multiple regression analyses suggest that self-esteem and mastery may be more salient predictors of depression and anxiety symptoms than are specific coping strategies.

Adaptation, Psychological↗

PubMed2002

Functional morphology of the hindlimb of tupaiids (Mammalia, Scandentia) and its phylogenetic implications.

In this study, the hindlimb of 12 species of tupaiids was analyzed functionally and compared to that of primates, dermopterans, and chiropterans. Many aspects of the tupaiid hindlimb vary in relation to differential substrate use. These differences include width of the ilium, shape of the acetabulum, size of the anterior inferior iliac spine, size of the greater and third trochanters, depth of the femoral condyles, shape of the patellar groove, and size of the tibial tuberosity. The hindlimb of the arboreal Ptilocercus lowii, the only ptilocercine, is better adapted for arboreal locomotion, whereas that of tupaiines is better adapted for rapid terrestrial (or scansorial) locomotion. The hindlimb of Ptilocercus seems to be habitually flexed and has more joint mobility, a condition necessary for movement on uneven, discontinuous arboreal supports. The tarsus of Ptilocercus facilitates inversion of the foot and its grasping hallux is capable of a great range of abduction. Tupaiines, on the other hand, are characterized by more extended hindlimbs and less mobility in their joints. These restricted joints limit movements more to the parasagittal plane, which increases the efficiency of locomotion on a more even and continuous surface like the ground. The hindlimb of tupaiines is adapted for powerful flexion and extension. Even the most arboreal tupaiines remain similar to terrestrial tupaiines in their hindlimb morphology, which probably reflects the terrestrial ancestry of Tupaiinae (but not Tupaiidae). Many attributes of the tupaiid hindlimb, especially those of the foot, reflect the arboreal ancestry of Tupaiidae and it is proposed that the ancestral tupaiid was arboreal like Ptilocercus. Also, compared to the hindlimb character states of tupaiines, those of Ptilocercus are more similar to those of other archontans, and it is proposed that the hindlimb features of Ptilocercus are primitive for the Tupaiidae. Hence, Ptilocercus should be considered in any phylogenetic analysis that includes Scandentia.

Animals↗

PubMed2005

Endoscopic techniques for rejuvenation of the midface.

Esthetic facial rejuvenation has gained widespread acceptance among the general public. As more and younger patients seek facial rejuvenation, surgeons have been searching for improved techniques, providing longer-lasting, natural-appearing results while decreasing peri- and postoperative sequelae. Toward this end, the endoscope was adapted to esthetic facial surgery. The intent of this article is to provide (1) the author's bias to rejuvenation of the midface and (2) an in-depth review in how the endoscope can be useful for selective rejuvenation of the midface.

Blepharoplasty↗

PubMed2006

Difference in sensorimotor adaptation to horizontal and vertical mirror distortions during ballistic arm movements.

When learning a novel motor task, the sensorimotor system must develop new strategies to efficiently control the limb(s) involved, and this adaptation appears to be developed through the construction of a behavioral map known as an 'internal model'. A common method to uncover the mechanisms of adaptation and reorganization processes is to expose the system to new environmental conditions, typically by introducing visual or mechanical distortions. The present study investigated the adaptation mechanisms of the human sensorimotor system to horizontal and vertical mirror distortions (HMD and VMD) during the execution of fast goal-directed arm movements. Mirror distortions (MDs) were created by means of virtual visual feedback on a computer screen while the movement was executed on a graphics tablet. Twenty healthy adult participants were recruited and assigned to one of two groups of 10 people each. Tests were divided in two subsequent blocks of five trials. The first block consisted of trials with no mirror distortion (NMD), while the second block was recorded when exposing one group to HMD and the other to VMD. Both MDs resulted in kinematic changes: during the tests with the MDs the participants did not reach the performance level found at the NMD test. Motor performance during HMD appeared to be globally better than during VMD and the adaptation process to VMD appeared to be slower than to HMD, but data interpretation was hampered by large within-participant and between-participant variability. In-depth analyses of the data revealed that most of the motor performance information was contained in the direction of movement. The data supported the idea that the internal model for HMD was already partially built.

Adult↗

PubMed2002

The educational preparation of undergraduate nursing students in pharmacology: a survey of lecturers' perceptions and experiences.

BACKGROUND: Nurses have key responsibilities in the administration and management of medication therapy and client education. It is of some concern therefore that the literature indicates that nurses are inadequately prepared in this area. AIMS: This paper explores the perceptions and expectations of lecturers about teaching and learning pharmacology in preregistration nursing courses. RESEARCH METHODS: Questionnaires were distributed to lecturers involved in teaching pharmacology to undergraduate nursing students during 2000. The questionnaire was distributed to all university campuses (n = 13) in Victoria, Australia, that are involved in undergraduate nursing education. The questionnaire was an adaptation of the survey instrument used in the Nursing and Medication Education [NAME] project and examined in this questionnaire: the integration of pharmacology teaching into nursing, range and depth of classroom-based pharmacology teaching, approaches to teaching and learning, nursing practice in a clinical context, related importance of patient education and communication skills, and the appropriate professional background of academics teaching pharmacology to preregistration nursing students. RESULTS: There was great variation between institutions as to the number of hours devoted to pharmacology and when it was offered. A number of respondents indicated that they were dissatisfied with the preparation of graduates and their knowledge base in pharmacology. LIMITATIONS: The study was limited by a low response rate of 34%. CONCLUSIONS: A review of nursing curricula is required to improve the knowledge base of nurses in pharmacology and to facilitate their skills in life-long learning.

Attitude of Health Personnel↗

PubMed2001

Thermal resistance of chicken (Gallus domesticus) plumage: a comparison between broiler and free-range birds.

1. We compared Ross chickens reared under broiler and free-range conditions to see whether there was a difference in thermal resistance of the plumage. 2. There was no difference in resistance to heat loss attributable to rearing environment for plumage from the back and leg but there was a significant difference in the pectoral region. 3. Free-range birds had a thicker plumage and a higher total resistance to heat transfer in the pectoral region, despite showing a lower resistance per unit depth than broiler birds. The pectoral plumage was more heavily soiled in broiler birds, which is the most likely explanation for the higher resistance per unit depth. 4. We suggest that behavioural selection of microclimate is likely to be a more important determinant of heat balance in free-range birds than intrinsic plumage adaptations.

Adaptation, Physiological↗

PubMed1996

Physical aspects of total-body irradiation at the Middlesex Hospital (UCL group of hospitals), London 1988-1993: I. Phantom measurements and planning methods.

This paper, which is divided into parts I and II, describes the physical aspects of work on total-body irradiation (TBI) at the Middlesex Hospital, London, from 1988 to 1993. Irradiation is fractionated and bi-lateral with horizontal accelerator photon beams of 8 MV (1988-1992) at a source-surface distance (SSD) of 3.36 m and 10 MV (1992-1993) at an SSD of 4.62 m. The main aims were maximum patient comfort, a simple, accurate set-up with overall times per fraction of 30 min or less, dose homogeneity throughout the body within +/- 10 to +/- 15%, pre-irradiation treatment planning on nine CT slices using our commercial IGE RTplan (1988-1992) and Target 2 (1992-1993) treatment planning systems and, most important, verification of the plans by in vivo dosimetry to within +/- 5%. Verification of the planned lung doses, which are distributed over five CT slices, was given special attention. In part I of this paper we describe the preliminary work, most of which was done prior to patient treatment. This consisted of standard dosimetric measurements (central axis depth doses, beam profiles at several depths, build-up and build-down curves, beam output calibrations, effect of body compensators, etc), in evaluating silicon diode dosimeters for in vivo dosimetry and of adapting and verifying the methods of treatment planning for TBI conditions. The results obtained with phantoms, including a Rando body phantom, showed that, in principle, our aims could be achieved. The final proof depended, however, on an analysis of the results of the in vivo work and this forms the subject of part II of this paper.

Algorithms↗

PubMed2004

A modeling approach for burn scar assessment using natural features and elastic property.

A modeling approach is presented for quantitative burn scar assessment. Emphases are given to: 1) constructing a finite-element model from natural image features with an adaptive mesh and 2) quantifying the Young's modulus of scars using the finite-element model and regularization method. A set of natural point features is extracted from the images of burn patients. A Delaunay triangle mesh is then generated that adapts to the point features. A three-dimensional finite-element model is built on top of the mesh with the aid of range images providing the depth information. The Young's modulus of scars is quantified with a simplified regularization functional, assuming that the knowledge of the scar's geometry is available. The consistency between the relative elasticity index and the physician's rating based on the Vancouver scale (a relative scale used to rate burn scars) indicates that the proposed modeling approach has high potential for image-based quantitative burn scar assessment.

Algorithms↗

PubMed2005

Root architecture and wind-firmness of mature Pinus pinaster.

This study aims to link three-dimensional coarse root architecture to tree stability in mature timber trees with an average of 1-m rooting depth. Undamaged and uprooted trees were sampled in a stand damaged by a storm. Root architecture was measured by three-dimensional (3-D) digitizing. The distribution of root volume by root type and in wind-oriented sectors was analysed. Mature Pinus pinaster root systems were organized in a rigid 'cage' composed of a taproot, the zone of rapid taper of horizontal surface roots and numerous sinkers and deep roots, imprisoning a large mass of soil and guyed by long horizontal surface roots. Key compartments for stability exhibited strong selective leeward or windward reinforcement. Uprooted trees showed a lower cage volume, a larger proportion of oblique and intermediate depth horizontal roots and less wind-oriented root reinforcement. Pinus pinaster stability on moderately deep soils is optimized through a typical rooting pattern and a considerable structural adaptation to the prevailing wind and soil profile.

Biomechanical Phenomena↗

PubMed1976

Foundations of health education.

Health education is "the process of providing or utilizing experiences for favorably influencing understanding, attitudes, and practices relating to individual, family, and community health. As an applied science it draws its content from a variety of sources. The paradigm which depicts the foundations of health education can be visualized as five vertical pillars consisting of sociocultural, educational, psycho-behavioral, legal, and scientific foundations supporting the work of the health educator. While the components within each pillar may be altered with new developments and advances over time, the model is broad enough in scope to incorporate the changes without altering its purpose. The foundations of health viewed in this light can easily display the depth of the health education profession and will serve to orient the novice and future health educators of the underpinnings of their profession. This framework could easily be adapted for study on the college level and should serve as an orientation to those students planning to major in health.

Behavior↗

PubMed2003

Effects of amplitude modulation on the coding of interaural time differences of low-frequency sounds in the inferior colliculus. II. Neural mechanisms.

In our companion paper, we reported on interaural time difference (ITD)-sensitive neurons that enhanced, suppressed, or did not change their response when identical AM was added to both ears. Here, we first examined physical factors such as the difference in the interaural correlation, spectrum, or energy between the modulated and unmodulated signals. These were insufficient to explain the observed enhancement and suppression. We then examined neural mechanisms by selectively modulating the signal to each ear, varying modulation depth, and adding background noise to the unmodulated signal. These experiments implicated excitatory and inhibitory monaural inputs to the inferior colliculus (IC). These monaural inputs are postulated to adapt to an unmodulated signal and adapt less to a modulated signal. Thus enhancement or suppression is created by the convergence of these excitatory or inhibitory inputs with the inputs from the binaural comparators. Under modulation, the role of the monaural input is to shift the threshold of the IC neuron. Consistent with this role, background noise mimicked the effect of modulation. Functionally, enhancement and suppression may serve in detecting the degree of modulation in a sound source while preserving ITD information.

Acoustic Stimulation↗

PubMedDate not supplied

[Biomechanical significance of the acetabular roof and its reaction to mechanical injury].

INTRODUCTION: The introduction of morphometry into the quantitative analysis of the bone system and functional adaptation of acetabulum to mechanical damages and injuries enabled a relatively simple and acceptable examination of morphological acetabular changes in patients with damaged hip joints. Measurements of the depth and form of acetabulum can be done by radiological methods, computerized tomography and ultrasound (1-9). AIM OF STUDY: The aim of the study was to obtain data on the behaviour of acetabular roof, the so-called "eyebrow", by morphometric analyses during different mechanical injuries. METHOD: Clinical studies of the effect of different loads on acetabular roof were carried out in 741 patients. Radiographic findings of 400 men and 341 women were analysed. The control group was composed of 148 patients with normal hip joints. Average age of the patients was 54.7 years and that of control subjects 52.0 years. Data processing was done for all examined patients. RESULTS: On the basis of our measurements the average size of female "eyebrow" ranged from 24.8 mm to 31.5 mm with standard deviation of 0.93 and in men from 29.4 mm to 40.3 mm with standard deviation of 1.54. The average size in the whole population was 32.1 mm with standard deviation of 15.61. Statistical analyses revealed high correlation coefficients between the age and "eyebrow" size in men (r = 0.124; p < 0.05); it was statically in inverse proportion (Graph 1). However, in female patients the correlation coefficient was statistically significant (r = 0.060; p > 0.05). The examination of the size of collodiaphysial angle and length of "eyebrow" revealed that "eyebrow" length was in inverse proportion to the size of collodiaphysial angle (r = 0.113; p < 0.05). The average "eyebrow" length in relation to the size of collodiaphysial angle ranged from 21.3 mm to 35.2 mm with standard deviation of 1.60. There was no statistically significant correlation between the "eyebrow" size and Wiberg's angle in male (r = 0.049; p > 0.05) and female (r = 0.005; p > 0.05) patients. The "eyebrow" length was proportionally dependent on the size of the shortened extremity in all examined subjects. This dependence was statistically significant both in female (r = 0.208; p < 0.05) and male (r = 0.193; p < 0.05) patients. The study revealed that fossa acetabuli was forward and downward laterally directed. The size, form and cross-section of acetabulum changed during different loads. Dimensions and morphological changes in acetabulum showed some but unimportant changes in comparison to that in the control group. These findings are graphically presented in Figure 5 and numerically in Tables 1 and 2. DISCUSSION: The study of spatial orientation among hip joints revealed that fossa acetabuli was forward and downward laterally directed; this was in accordance with results other authors (1, 7, 9, 15, 18). There was a statistically significant difference in relation to the "eyebrow" size between patients and normal subjects (t = 3.88; p < 0.05). The average difference of "eyebrow" size was 6.892 mm. A larger "eyebrow" was found in patients with normally loaded hip. There was also a significant difference in "eyebrow" size between patients and healthy female subjects (t = 4.605; p < 0.05). A larger "eyebrow" of 8.79 mm was found in female subjects with normally loaded hip. On the basis of our study it can be concluded that the findings related to changes in acetabular roof, the so-called "eyebrow", are important in diagnosis, follow-up and therapy of pathogenetic processes of these disorders.

Acetabulum↗