Synthesis, cytotoxicity, and hydroxyapatite formation in 27-Tris-SBF for sol-gel based CaO-P2O5-SiO2-B2O3-ZnO bioactive glasses

CaO-P2O5-SiO2-B2O3-ZnO bioactive glasses were prepared via an optimized sol-gel method. The current investigation was focused on producing novel zinc based calcium phosphoborosilicate glasses and to evaluate their mechanical, rheological, and biocompatible properties. The morphology and composition of these glasses were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The particle size, mechanical and flexural strength was also determined. Furthermore, the zeta potential of all the glasses were determined to estimate their flocculation tendency. The thermal analysis and weight loss measurements were carried out using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) respectively. For assessing the in-vitro bioactive character of synthesized glasses, the ability for apatite formation on their surface upon their immersion in simulated body fluid (SBF) was checked using SEM and pH measurements. MTS assay cytotoxicity assay and live-dead cell viability test were conducted on J774A.1 cells murine macrophage cells for different glass concentrations.

Expanding the search for a linear separability constraint on category learning

Formal models of categorization make different predictions about the theoretical importance of linear separability. Prior research, most of which has failed to find support for a linear separability constraint on category learning, has been conducted using tasks that involve learning two categories with a small number of members. The present experiment used four categories with three or nine patterns per category that were either linearly separable or not linearly separable. With overall category structure equivalent across category types, the linearly separable categories were found to be easier to learn than the not linearly separable categories. An analysis of individual participants' data showed that there were more participants operating under a linear separability constraint when learning large categories than when learning small ones. Formal modeling showed that an exemplar model could not account for many of these data. These results are taken to support the existence of multiple processes in categorization.

Transesophageal echocardiography: first-line imaging for aortic diseases

Transesophageal echocardiography (TEE) is now commonly used to evaluate the thoracic aorta, because it is widely available and provides high-resolution images and flow information by Doppler. This article reviews the essential features on TEE of acute and chronic aortic diseases, such as aortic dissection, aneurysm, and atherosclerosis, and discusses its strengths, weaknesses, and indications.

Effect of asthma on the quality of life among children and their caregivers in the Atlanta Empowerment Zone

BACKGROUND AND OBJECTIVE

Asthma is the most common chronic pediatric disease and exacts a toll on the health-related quality of life of affected children and their primary caregivers. This investigation describes the relationship between the clinical severity of asthma among inner-city children and their quality of life and that of their primary adult caregivers.

METHODS

Telephone interview data were collected from individual adult caregivers of 5-12-year-old children with asthma. Questions addressed the history, diagnosis, and management of the child's asthma, the child's family and social background, the family's socioeconomic status, the caregiver's knowledge and attitude about asthma, and the health-related quality of life of both the child and the caregiver. An asthma severity score was calculated from the caregiver's responses to questions about their child's wheezing frequency, nocturnal and early morning symptoms, and speaking during an asthma attack, as well as the impact of the disease on their child's physical activity and breathing during the prior 4-month period. A clinical asthma triage score was determined from information collected at the emergency department about the child's oxygen saturation, alertness, use of accessory respiratory muscles, extent of breathlessness, and peak expiratory flow. Spearman correlation coefficients were used to identify association between quality of life and disease severity, caretaker's asthma knowledge, and functional impact of asthma symptoms.

RESULTS

Data from 240 of 755 eligible children were analyzed. Most children were younger than 11 years, male, black, and non-Hispanic. The children's median duration of asthma diagnosis was 86% of their life (range less than 1 to 11.3 years, median 5.0 years). Of the primary caregivers, 69% had at least completed high school, and 90% reported a total monthly household income of $1,600 or less. The maximum possible quality-of-life score and the median for caregivers were 91 and 70, respectively; for children, the same scores were 69 and 58, respectively. In addition, there was significant negative correlation of the quality-of-life scores of both the caregivers and children with the number of schooldays the children missed (r = -0.24 and r = -0.26, respectively, P < .001 for both) and the caregivers' and children's asthma severity scores (r = -0.39 and r = -0.47, respectively, P < .001 for both). The quality-of-life scores of the children and caregivers did not correlate significantly with the asthma triage scores.

CONCLUSIONS

The questionnaires captured baseline quality-of-life information about this urban population and will facilitate longitudinal monitoring. The fact that the quality-of-life scores of children with asthma correlated with those of their adult caregivers, but not with their clinical triage scores, highlights the impact of asthma on families and the importance of having a long-term comprehensive management plan that is not based on exacerbations, but that includes both the children and their primary caregivers.

Concepts and transformational knowledge

The effect of exposure to principled change in concept formation was investigated in four experiments. In Experiment 1, participants were trained on either patterns that transformed systematically or control patterns that were distorted randomly. Training on transformational patterns produced concepts that were more resistant to false intrusions and decay. Experiment 2 separated the relative influences of transformational knowledge and pairwise similarity. Participants were able to identify the next pattern in a transformational sequence even though the foils were closer to the training patterns. Experiment 3 investigated whether participants use transformational information in a speeded categorization task. Participants were faster at classifying patterns that continued a transformational path than patterns that fell off the path, only if they had trained on the transformational patterns in a systematic order. Experiment 4 used multidimensional scaling to explore the psychological structure of transformational knowledge following training. Analyses revealed clear evidence of a transformational path with systematic training. Implications for theories of similarity and categorization are discussed.

Influence of manipulated category knowledge on prototype classification and recognition

The recognition and classification of category members was explored, following a variable number of learning trials. In Experiment 1, subjects received 1 or 9 learning trials, followed by a recognition-then-classification test containing old, new, prototype, and foil patterns. In Experiment 2, subjects received 1, 6, or 12 trials, and made either classification or recognition judgments. In each experiment, classification accuracy for all item types was at near-chance performance after a single trial but steadily increased with increased learning trials. On the transfer test, oldness judgments were highest for the category prototype after a single trial. However, with increased learning trials, oldness judgments increased for old instances and decreased for the category prototype and new instances. We suggest that false recognition of the category prototype, especially after a single learning trial, need not reflect an abstraction process. We discuss the possibility that an abstracted prototype may emerge with additional learning as an unfamiliar, ideal point.

Evaluation of mitral leaflet motion by echocardiography and jet direction by Doppler color flow mapping to determine the mechanisms of mitral regurgitation

OBJECTIVES

This study was designed to assess the accuracy of two-dimensional and Doppler echocardiography in determining the mechanism of mitral regurgitation, as compared with direct inspection of the valve at operation.

BACKGROUND

Valve repair for mitral regurgitation offers substantial advantages over valve replacement, but it is technically more demanding and requires understanding of the mechanism of dysfunction.

METHODS

We studied 286 patients undergoing mitral valve repair. Intraoperative two-dimensional echocardiography was used to classify mitral leaflet motion as excessive, normal or restricted. Doppler color flow mapping was used to evaluate the direction and origin of the mitral regurgitant jet. Two-dimensional and Doppler echocardiography were compared with intraoperative surgical determination of the mechanism of dysfunction, which also classified leaflet motion as excessive, normal or restricted.

RESULTS

Two-dimensional and Doppler echocardiography accurately diagnosed the mechanism of mitral regurgitation in 123 (93%) of 132 patients with posterior leaflet prolapse or flail, 30 (94%) of 32 patients with anterior leaflet prolapse or flail, 11 (44%) of 25 patients with bileaflet prolapse or flail, 6 (75%) of 8 patients with papillary muscle elongation or rupture, 31 (91%) of 34 patients with restricted leaflet motion or rheumatic thickening, 21 (72%) of 29 patients with ventricular-annular dilation and 8 (62%) of 13 patients with a leaflet perforation or cleft. Of 13 patients with two mechanisms of dysfunction by surgical inspection, two-dimensional and Doppler echocardiography correctly diagnosed one of the two mechanisms in 12 patients (92%), and both mechanisms in 5 patients (38%). Overall, echocardiographic determination of leaflet motion and Doppler determination of jet direction accurately diagnosed the mechanism of dysfunction in 242 (85%) of 286 patients.

CONCLUSIONS

Echocardiography before mitral valvuloplasty provides a dynamic appraisal of the mechanism of dysfunction, enabling the surgeon to systematically understand the dysfunction and successfully apply the correct procedures to eliminate mitral regurgitation without valve replacement.

Reallocation of visual attention

Attentional movement time was investigated within and across hemifields in a discrimination task in which retinal acuity was controlled. Ss discriminated targets in a two-alternative, forced-choice latency paradigm. In Experiments 1-3, costs were mediated by distance, even though it was varied independently of acuity. In Experiments 4 and 7, with distance held constant, costs were equivalent for crossing the vertical and horizontal meridians and for crossing 1 and 2 meridians. However, crossing 1 meridian produced costs that were less than the costs for shifts to unexpected locations in the same quadrant, partially replicating the inhibitory aftereffect of Tassinari, Aglioti,Chelazzi,Marzi,and Berlucchi (1987). An explanation based on a combination of analog movement (Tsal, 1983) and attentional distribution (Downing & Pinker, 1985; Hughes & Zimba, 1987; Tassinari et al., 1987) models was discussed.

Reallocation of visual attention

Attentional movement time was investigated within and across hemifields in a discrimination task in which retinal acuity was controlled. Ss discriminated targets in a two-alternative, forced-choice latency paradigm. In Experiments 1-3, costs were mediated by distance, even though it was varied independently of acuity. In Experiments 4 and 7, with distance held constant, costs were equivalent for crossing the vertical and horizontal meridians and for crossing 1 and 2 meridians. However, crossing 1 meridian produced costs that were less than the costs for shifts to unexpected locations in the same quadrant, partially replicating the inhibitory aftereffect of Tassinari, Aglioti,Chelazzi,Marzi,and Berlucchi (1987). An explanation based on a combination of analog movement (Tsal, 1983) and attentional distribution (Downing & Pinker, 1985; Hughes & Zimba, 1987; Tassinari et al., 1987) models was discussed.

Sensitization of the visual field

Three experiments investigated the identification or localization of a letter that was displaced from the fixation point by 1 degree-3 degrees. The subject's task was to identify a fixated letter and identify (Experiment 1) or localize (Experiments 2 and 3) the displaced letter. On uncued trials, the displaced letter could appear at any of eight locations on any of three rings surrounding the fixated letter; on cued trials, the ring containing the displaced letter was specified. The results indicated that cuing improved subjects' identification and localization of the displaced letter. Invalid cuing (Experiment 3) produced costs comparable in magnitude to the benefits. The distance of the target from the cued ring determined cost, but costs were unaffected by the appearance of a target within the presumed beam of attention. It was proposed that attention should be viewed as a general, rather than feature-specific, resource that can be voluntarily allocated to multiple regions of the visual field.